ArticleLiterature Review

Regulation and Role of Neuroglobin and Cytoglobin Under Hypoxia

February 2007
Advances in Experimental Medicine and Biology 618:169-80

February 2007
618:169-80

DOI:10.1007/978-0-387-75434-5_13

Source
PubMed

Authors:

Thorsten Burmester

University of Hamburg

Thomas Hankeln

Johannes Gutenberg-Universität Mainz

Neuroglobin (Ngb) and cytoglobin (Cygb) are two novel members of the globin superfamily that are ubiquitously present in vertebrates. Their exact physiological roles are still uncertain. Here we review the expression of Ngb and Cygb, with particular emphasis on their regulation and potential role under hypoxia. Ngb expression is confined to neurons and some endocrine tissues. At the subcellular level, Ngb is associated with the presence of mitochondria and thus linked to the oxidative metabolism. Hypoxia or ischemic insults most likely do not strongly increase Ngb levels in the rodent brain. This might be explained by the fact that most mammals are not adapted to low oxygen levels. In zebrafish and turtle, however, which live in an environment with naturally changing oxygen conditions, hypoxia dramatically increases Ngb expression in the brains. We also found that hypoxia-tolerant species (e.g. the mole rat Spalax and goldfish) express more Ngb in their brains than their oxygen-deprivation sensitive relatives. These data suggest that Ngb may have a myoglobin-like role and supplies oxygen to the respiratory chain of the metabolically highly active neurons, or protect them from reactive oxygen species. Cygb is predominantly expressed in fibroblasts and related cell types, but also in distinct nerve cell populations. Cygb levels are significantly elevated at low oxygen levels in the fibroblast cell lineage. Cell culture data suggest that in fibroblasts Cygb is involved in cell proliferation, possibly in collagen synthesis. In neurons, there is evidence for an additional role of Cygb related to nitric oxide metabolism.

The novel thiosemicarbazone, di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), inhibits neuroblastoma growth in vitro and in vivo via multiple mechanisms

Article

Full-text available

Sep 2016
J HEMATOL ONCOL

Background: Neuroblastoma is a relatively common and highly belligerent childhood tumor with poor prognosis by current therapeutic approaches. A novel anti-cancer agent of the di-2-pyridylketone thiosemicarbazone series, namely di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), demonstrates promising anti-tumor activity. Recently, a second-generation analogue, namely di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), has entered multi-center clinical trials for the treatment of advanced and resistant tumors. The current aim was to examine if these novel agents were effective against aggressive neuroblastoma in vitro and in vivo and to assess their mechanism of action. Methods: Neuroblastoma cancer cells as well as immortalized normal cells were used to assess the efficacy and selectivity of DpC in vitro. An orthotopic SK-N-LP/Luciferase xenograft model was used in nude mice to assess the efficacy of DpC in vivo. Apoptosis in tumors was confirmed by Annexin V/PI flow cytometry and H&E staining. Results: DpC demonstrated more potent cytotoxicity than Dp44mT against neuroblastoma cells in a dose- and time-dependent manner. DpC significantly increased levels of phosphorylated JNK, neuroglobin, cytoglobin, and cleaved caspase 3 and 9, while decreasing IkBα levels in vitro. The contribution of JNK, NF-ĸB, and caspase signaling/activity to the anti-tumor activity of DpC was verified by selective inhibitors of these pathways. After 3 weeks of treatment, tumor growth in mice was significantly (p < 0.05) reduced by DpC (4 mg/kg/day) given intravenously and the agent was well tolerated. Xenograft tissues showed significantly higher expression of neuroglobin, cytoglobin, caspase 3, and tumor necrosis factor-α (TNFα) levels and a slight decrease in interleukin-10 (IL-10). Conclusions: DpC was found to be highly potent against neuroblastoma, demonstrating its potential as a novel therapeutic for this disease. The ability of DpC to increase TNFα in tumors could also promote the endogenous immune response to mediate enhanced cancer cell apoptosis.

THE EXPRESSION PROFILE OF CYTOGLOBIN IN HUMAN FIBROTIC LUNG, AND THE PROTECTIVE ROLE OF CYTOGLOBIN IN HYPOXIA AND OXIDATIVE STRESS IN VITRO

Article

Melinda Carpenter

Extensive identification of serum metabolites related to microbes in different gut locations and evaluating their associations with porcine fatness

Article

Full-text available

Mar 2023

Gut microbiota plays important roles in host metabolism. Whether and how much the gut microbiota in different gut locations contributes to the variations of host serum metabolites are largely unknown, because it is difficult to obtain microbial samples from different gut locations on a large population scale. Here, we quantified the gut microbial compositions using 16S rRNA gene sequencing for 1070 samples collected from the ileum, cecum and faeces of 544 F6 pigs from a mosaic pig population. Untargeted metabolome measurements determined serum metabolome profiles. We found 1671, 12,985 and 103,250 significant correlations between circulating serum metabolites and bacterial ASVs in the ileum, cecum, and faeces samples. We detected nine serum metabolites showing significant correlations with gut bacteria in more than one gut location. However, most metabolite‐microbiota pairwise associations were gut location‐specific. Targeted metabolome analysis revealed that CDCA, taurine, L‐leucine and N‐acetyl‐L‐alanine can be used as biomarkers to predict porcine fatness. Enriched taxa in fat pigs, for example Prevotella and Lawsonia intracellularis were positively associated with L‐leucine, while enriched taxa in lean pigs, such as Clostridium butyricum, were negatively associated with L‐leucine and CDCA, but positively associated with taurine and N‐acetyl‐L‐alanine. These results suggested that the contributions of gut microbiota in each gut location to the variations of serum metabolites showed spatial heterogeneity.

Neuroglobin and mitochondria: The impact on neurodegenerative diseases

Article

Mar 2021

Dysfunctional mitochondria have severe consequences on cell functions including Reactive Oxygen Specie (ROS) generation, alteration of mitochondrial signaling, Ca²⁺ buffering, and activation of apoptotic pathway. These dysfunctions are closely linked with degenerative diseases including neurodegeneration. The discovery of neuroglobin (NGB) as an endogenous neuroprotective protein, which effects seem to depend on its mitochondrial localization, could drive new therapeutic strategies against aged-related neurodegenerative diseases. Indeed, high levels of NGB are active against several brain injuries, including neurodegeneration, hypoxia, ischemia, toxicity, and nutrient deprivation opening a new scenario in the comprehension of the relationship between neural pathologies and mitochondrial homeostasis. In this review, we provide the current understanding of the role of mitochondria in neurodegeneration and discuss structural and functional connection between NGB and mitochondria with the purpose of defining a novel mitochondrial-based neuroprotective mechanism(s).

Relative Hypoxia in Immunized Mice Spleen Macrophages as Indicated by Hypoxia Inducible Factors, Cytoglobin and Peroxisome Proliferator Activated Receptor Gamma Coactivator (PGC)‑1α

Article

Full-text available

Jan 2020

Neuroglobin: From structure to function in health and disease

Article

Nov 2016
MOL ASPECTS MED

In 2000, the third member of the globin family was discovered in human and mouse brain and named neuroglobin (Ngb). Ngb is a monomeric 3-over-3 globin structurally similar to myoglobin and to the α- and β-chains of hemoglobin, however it displays a bis-histiyl six-coordinate heme-Fe atom. Therefore, ligand binding to the Ngb metal center is limited from the dissociation of the distal His(E7)64-Fe bond. From its discovery, more than 500 papers on Ngb structure, expression, reactivity, and localization have been published to highlight biochemical properties and the role(s) in health and disease. In vivo experiments have shown that increased levels of Ngb significantly protect both heart and brain from hypoxic/ischemic and oxidative stress-related insults, whereas decreased Ngb levels lead to an exacerbation of tissue injuries. Although some contradictory data emerged, human Ngb over-expression has been hypothesized to protect neurons from mitochondrial disfunctions and neurodegenerative disorders such as Alzheimer's disease, and to play a shielding role of cancer cells. Recently, the recognition of Ngb interactors and inducers enlarges the functions of this stress-inducible globin, opening new therapeutic approaches to prevent neuronal cell death. Here, structural and functional aspects of human Ngb are examined critically to highlight its roles in health and disease.

Neuroglobin and Estrogen Receptors: A New Pathway of Cell Survival and Cell Death Balance

Article

Full-text available

Apr 2015
Immunol Endocr Metab Agents Med Chem

17β-estradiol (E2) plays a crucial role in the maintenance of body homeostasis including the balance between cell survival and apoptosis. Intriguingly, estrogen receptor subtypes (i.e., ERα and ERβ) trigger opposite pathways which drive E2 target cells to proliferation (via ERα) or apoptosis (via ERβ). Recently, we identified neuroglobin (NGB) as an E2 inducible heme-protein involved in hormone regulation of cell proliferation and apoptosis in neuronal and non-neuronal cell lines. In particular, E2 increases NGB protein level mainly in the mitochondria preventing the release of cytochrome c after an oxidative stress injury. Here, the mechanisms underlying E2-induced NGB up-regulation, the involvement of signal transduction pathways and of specific ER subtypes will be discussed in order to propose a possible new E2-dependent scenario at the root of cell survival and cell death balance.

Interaction of apoNeuroglobin with heme–Aβ complexes relevant to Alzheimer’s disease

Article

Feb 2015

Heme-Aβ complexes are known to produce toxic partially reduced oxygen species (PROS), catalyze oxidation of neurotransmitters and have been associated with Alzheimer's disease (AD). Neuroglobin (Ngb) play a crucial neuroprotective role against oxidative damage, hypoxic injuries, stroke and apoptosis of neuronal cells. In this study, the interaction of heme-Aβ with apoNeuroglobin (apoNgb) has been investigated using a combination of spectroscopic techniques. Absorption and resonance Raman data confirm that apoNgb can uptake heme from heme-Aβ and constitute a six-coordinate low-spin ferric heme-active site identical to that of Ngb. ApoNgb can also uptake heme from reduced heme-Aβ resulting in the formation of ferrous Ngb. The rate of the heme transfer reaction has been found to be of the order of 10(6) M(-1) s(-1). The reaction is faster for oxidized heme-Aβ than the reduced form. The amount of PROS formation by heme-Aβ complexes has been found to diminish drastically after reaction with apoNgb. ApoNgb can also sequester ligand-bound heme from heme-Aβ, e.g., the CO-bound heme from heme-Aβ-CO complex resulting in the formation of Ngb-CO complex. Additionally, ApoNgb can sequester heme from self-assembled monolayer (SAM) of surface-bound heme-Aβ formed over Au surface. This heme sequestration by apoNgb from heme-Aβ not only diminishes heme-induced toxicity but more significantly it produces Ngb which has well-documented neuroprotective role and can thereby potentially reduce risks associated with AD.

Molecular Response of Estuarine Fish to Hypoxia: A Comparative Study with Ruffe and Flounder from Field and Laboratory

Article

Full-text available

Mar 2014
PLOS ONE

On a global scale, the frequencies and magnitudes of hypoxic events in coastal and estuarine waters have increased dramatically over the past 20 years. Fish populations are suitable indicators for the assessment of the quality of aquatic ecosystems, as they are omnipresent and often comprise a variety of different lifestyles and adaption strategies. We have investigated on the molecular level the impact of hypoxia on two fish species typical of European estuaries. We monitored the expression of eleven putatively hypoxia-responsive genes by means of quantitative real-time RT-PCR in brains, gills and hearts of the ruffe (Gymnocephalus cernua) and the flounder (Platichthys flesus). We first investigated the effect of naturally occurring hypoxia in the Elbe estuary. In a second approach, expression changes in the response to hypoxia were monitored under controlled laboratory conditions. The genes that showed the strongest effect were two respiratory proteins, myoglobin and neuroglobin, as well as the apoptosis enzyme caspase 3. As previously observed in other fish, myoglobin, which was considered to be muscle-specific, was found in brain and gills as well. Comparison of field and laboratory studies showed that - with the exception of the heart of flounder - that mRNA levels of the selected genes were about the same, suggesting that laboratory conditions reflect natural conditions. Likewise, trends of gene expression changes under hypoxia were the same, although hypoxia response was more pronounced in the Elbe estuary. In general, the flounder displayed a stronger response to hypoxia than the ruffe, suggesting that the flounder is more susceptible to hypoxia. The most pronounced differences were found among tissues within a species, demonstrating that hypoxia response is largely tissue-specific. In summary, our data suggest that laboratory experiments essentially mimic field data, but additional environmental factors enhance hypoxia response in nature.

Metabolic dynamics and prediction of sFGR and adverse fetal outcomes: a prospective longitudinal cohort study

Article

Full-text available

Nov 2023
BMC MED

Background Selective fetal growth restriction (sFGR) is an extreme complication that significantly increases the risk of perinatal mortality and long-term adverse neurological outcomes in offspring, affecting approximately 15% of monochorionic diamniotic (MCDA) twin pregnancies. The lack of longitudinal cohort studies hinders the early prediction and intervention of sFGR. Methods We constructed a prospective longitudinal cohort study of sFGR, and quantified 25 key metabolites in 337 samples from maternal plasma in the first, second, and third trimester and from cord plasma. In particular, our study examined fetal growth and brain injury data from ultrasonography and used the Ages and Stages Questionnaire-third edition subscale (ASQ-3) to evaluate the long-term neurocognitive behavioral development of infants aged 2–3 years. Furthermore, we correlated metabolite levels with ultrasound data, including physical development and brain injury indicators, and ASQ-3 data using Spearman’s-based correlation tests. In addition, special combinations of differential metabolites were used to construct predictive models for the occurrence of sFGR and fetal brain injury. Results Our findings revealed various dynamic patterns for these metabolites during pregnancy and a maximum of differential metabolites between sFGR and MCDA in the second trimester ( n = 8). The combination of l -phenylalanine, l -leucine, and l -isoleucine in the second trimester, which were closely related to fetal growth indicators, was highly predictive of sFGR occurrence (area under the curve [AUC]: 0.878). The combination of l -serine, l -histidine, and l -arginine in the first trimester and creatinine in the second trimester was correlated with long-term neurocognitive behavioral development and showed the capacity to identify fetal brain injury with high accuracy (AUC: 0.94). Conclusions The performance of maternal plasma metabolites from the first and second trimester is superior to those from the third trimester and cord plasma in discerning sFGR and fetal brain injury. These metabolites may serve as useful biomarkers for early prediction and promising targets for early intervention in clinical settings.

The ventricular-subventricular, subgranular and subcallosal zones: three niches of neural stem cells in the postnatal brain

Article

Full-text available

Apr 2023
EXP BRAIN RES

In the postnatal brain, three regions show high mitotic activity. These brain areas are neurogenic niches, and each niche harbors a microenvironment favorable for the proliferation and differentiation of neural stem cells. These multipotential cells maintain the capacity to self-renew and generate intermediate precursors that will differentiate into neuronal and glial lineages (astrocytes and oligodendrocytes). The most well-studied niches are the ventricular-subventricular zone (V-SVZ) of the lateral ventricles, the subgranular zone (SGZ) of the dentate gyrus in the hippocampus, and the subcallosal zone (SCZ), located in the limit between the corpus callosum and the hippocampal formation. The discovery of these three neurogenic niches has gained much interest in the field because they may be a therapeutic alternative in neural regeneration and neurodegenerative disorders. In this review, we describe in brief all these regions and explain their potential impact on solving some neurological conditions.

Spatially Targeted Proteomics of the Host–Pathogen Interface during Staphylococcal Abscess Formation

Article

Dec 2020

Staphylococcus aureus is a common cause of invasive and life-threatening infections that are often multidrug resistant. To develop novel treatment approaches, a detailed understanding of the complex host-pathogen interactions during infection is essential. This is particularly true for the molecular processes that govern the formation of tissue abscesses, as these heterogeneous structures are important contributors to staphylococcal pathogenicity. To fully characterize the developmental process leading to mature abscesses, temporal and spatial analytical approaches are required. Spatially targeted proteomic technologies such as micro-liquid extraction surface analysis offer insight into complex biological systems including detection of bacterial proteins and their abundance in the host environment. By analyzing the proteomic constituents of different abscess regions across the course of infection, we defined the immune response and bacterial contribution to abscess development through spatial and temporal proteomic assessment. The information gathered was mapped to biochemical pathways to characterize the metabolic processes and immune strategies employed by the host. These data provide insights into the physiological state of bacteria within abscesses and elucidate pathogenic processes at the host-pathogen interface.

Structure of Neuroglobin From Cold-Water Sponge Halisarca Dujardinii

Article

Full-text available

May 2020

The iron-containing protein neuroglobin (Ngb) involved in the transport of oxygen is generally considered the precursor of all animal globins. In this report, we studied the structure of Ngb of the cold-water sponge Halisarca dujardinii. In sponges, the oldest multicellular organisms, the Ngb gene contains three introns. In contrast to human Ngb, its promoter contains a TATA-box, rather than CG-rich motifs. In sponges, Ngb consists of 169 amino acids showing rather low similarity with its mammalian orthologues. It lacks Glu and Arg residues in positions required for prevention of hypoxia-related apoptosis. Nevertheless, Ngb contains both proximal and distal conserved heme-biding histidines. The primary structure of H. dujar-dinii neuroglobin predicted by sequencing was confirmed by mass-spectrometry analysis of recombinant Ngb expressed in E. coli. The high level of Ngb expression in sponge tissues suggests its possible involvement in the gas metabolism and presumably in other key metabolic processes in H. dujardinii.

Evaluation of neuroglobin and cytoglobin expression in adult rats exposed to silver nanoparticles during prepubescence

Article

Full-text available

Jun 2019
METAB BRAIN DIS

Silver nanoparticles (AgNPs) are clusters of silver atoms with diameters that range from 1 to 100 nm. Due to the various shapes and large surface areas, AgNPs have been employed in the food and textile industries and medical fields. Therefore, because of the widespread use of these compounds, the aim of this study was to evaluate the effect of AgNP exposure on the gene and protein expression levels of Neuroglobin (Ngb) and Cytoglobin (Cygb), in the rat cortex, hippocampus and cerebellum. Post-natal day (PND) 21 male Wistar rats were randomly divided into three groups. One group received 15 μg/kg body weight of AgNP by gavage another group received 30 μg/kg and the control group that received saline, from PND23 to PND58. On PND102 the animals were euthanized and the cortex, hippocampus and cerebellum were isolated and evaluated for gene and protein expression levels of Nbg and Cygb. The results demonstrated that the 30 μg/kg AgNP group displayed increased gene and protein expression of Cygb in the cortex. In the Hippocampus, AgNP exposure did not modulate gene or protein expression levels of Ngb and Cygb. In cerebellum the Ngb gene and protein expression was increased with both doses of AgNP. AgNP exposure during prepubescence can modulate the gene and protein expression levels of Ngb and Cygb in adulthood. Furthermore, the observed modulation was specific to the cerebellum, and cortex, and was dose dependent.

Selective overexpression of cytoglobin in stellate cells attenuates thioacetamide-induced liver fibrosis in mice

Article

Full-text available

Dec 2018

Abstract Cytoglobin (CYGB), discovered in hepatic stellate cells (HSCs), is known to possess a radical scavenger function, but its pathophysiological roles remain unclear. Here, for the first time, we generated a new transgenic (TG) mouse line in which both Cygb and mCherry reporter gene expression were under the control of the native Cygb gene promoter. We demonstrated that the expression of Cygb-mCherry was related to endogenous Cygb in adult tissues by tracing mCherry fluorescence together with DNA, mRNA, and protein analyses. Administration of a single dose (50 mg/kg) of thioacetamide (TAA) in Cygb-TG mice resulted in lower levels of alanine transaminase and oxidative stress than those in WT mice. After 10 weeks of TAA administration, Cygb-TG livers exhibited reduced neutrophil accumulation, cytokine expression and fibrosis but high levels of quiescent HSCs. Primary HSCs isolated from Cygb-TG mice (HSCCygb-TG) exhibited significantly decreased mRNA levels of α-smooth muscle actin (αSMA), collagen 1α1, and transforming growth factor β-3 after 4 days in culture relative to WT cells. HSCsCygb-TG were resistant to H2O2-induced αSMA expression. Thus, cell-specific overexpression of Cygb attenuates HSC activation and protects mice against TAA-induced liver fibrosis presumably by maintaining HSC quiescence. Cygb is a potential new target for antifibrotic approaches.

Molecular characterization and expression changes of cytoglobin genes in response to hypoxia in a Tibetan schizothoracine fish, Schizopygopsis pylzovi

Article

Full-text available

Jun 2019
FISH PHYSIOL BIOCHEM

Schizopygopsis pylzovi, an endemic fish of the subfamily Schizothoracinae, is comparatively well adapted to dissolved oxygen fluctuations in the aqueous environments of the Qinghai-Tibetan Plateau. Here, we cloned the complete cDNA of cytoglobin 1 and 2 (Cygb1 and Cygb2) from S. pylzovi and then investigated transcriptional changes of both genes in the selected tissues in response to hypoxia. Both the two genes had the standard exon-intron structure of vertebrate Mb genes but lacked an exon at downstream of the H helix (HC11.2) as seen in mammals. We applied severe hypoxia (4 h at PO2 = 3.6% saturation) and moderate hypoxia (72 h at PO2 = 36.0% saturation) to adult S. pylzovi. Under severe hypoxia, the Cygb1 mRNA levels decreased significantly in the liver, kidney, and brain, but increased significantly in the heart, while the Cygb2 mRNA levels downregulated significantly in the muscle and liver. But, the transcriptional activity of Cygb1 in muscle and that of Cygb2 in the kidney, brain, and heart remained almost unchanged. Under moderate hypoxia, the transcriptional activities of both genes in muscle and brain were turned down quickly after onset hypoxia, while in the liver, kidney, and heart, the transcriptional activities of both genes showed a short-term upregulation in different time periods of hypoxia exposure. Our data suggest that both the Cygb1 and Cygb2 in S. pylzovi are hypoxia-induced genes, and the responses of the transcription regulation of Cygb1 and Cygb2 genes to hypoxia are tissue specific and also depend on the hypoxia regime, which are different from that of other fish species.

Myoglobin: Oxygen Depot or Oxygen Transporter to Mitochondria? A Novel Mechanism of Myoglobin Deoxygenation in Cells (review)

Article

Feb 2018

In this review, we shortly summarize the data of our studies (and also corresponding studies of other authors) on the new mechanism of myoglobin (Mb) deoxygenation in a cell, according to which Mb acts as an oxygen transporter, and its affinity for the ligand, like in other transporting proteins, is regulated by the interaction with the target, in our case, mitochondria (Mch). We firstly found that contrary to previously formulated and commonly accepted concepts, oxymyoglobin (MbO2) deoxygenation occurs only via interaction of the protein with respiring mitochondria (low \({p_{{O_2}}}\) values are necessary but not sufficient for this process to proceed). Detailed studies of the mechanism of Mb–Mch interaction by various physicochemical methods using natural and artificial bilayer phospholipid membranes showed that: (i) the rate of MbO2 deoxygenation in the presence of respiring Mch fully coincides with the rate of O2 uptake by mitochondria from a solution irrespectively of their state (native coupled, freshly frozen, or FCCP-uncoupled), i.e. it is determined by the respiratory activity of Mch; (ii) Mb nonspecifically binds to membrane phospholipids of the outer mitochondrial membrane, while any Mb-specific protein or phospholipid sites on it are lacking; (iii) oxygen uptake by Mch from a solution and the uptake of Mb-bound oxygen are two different processes, as their rates are differently affected by proteins (e.g. lysozyme) that compete with MbO2 for binding to the mitochondrial membrane; (iv) electrostatic forces significantly contribute to the Mb–membrane interactions; the dependence of these interactions on ionic strength is provided by the local electrostatic interactions between anionic groups of phospholipids (the heads) and invariant Lys and Arg residues near the Mb heme pocket; (v) interactions of Mb with phospholipid membranes promote conformational changes in the protein, primarily in its heme pocket, without significant alterations in the protein secondary and tertiary structures; and (vi) Mb–membrane interactions lead to decrease in the affinity of myoglobin for O2, which could be monitored by the increase in the MbO2 autooxidation rate under aerobic conditions and under anaerobic ones, by the shift in the MbO2/Mb(2) equilibrium towards the ligand-free protein. The decrease in the affinity of Mb for the ligand should facilitate O2 dissociation from MbO2 at physiological \({p_{{O_2}}}\) values in cells.

Hippurate as a metabolomic marker of gut microbiome diversity: Modulation by diet and relationship to metabolic syndrome

Article

Full-text available

Oct 2017

Reduced gut microbiome diversity is associated with multiple disorders including metabolic syndrome (MetS) features, though metabolomic markers have not been investigated. Our objective was to identify blood metabolite markers of gut microbiome diversity, and explore their relationship with dietary intake and MetS. We examined associations between Shannon diversity and 292 metabolites profiled by the untargeted metabolomics provider Metabolon Inc. in 1529 females from TwinsUK using linear regressions adjusting for confounders and multiple testing (Bonferroni: P < 1.71 × 10⁻⁴). We replicated the top results in an independent sample of 420 individuals as well as discordant identical twin pairs and explored associations with self-reported intakes of 20 food groups. Longitudinal changes in circulating levels of the top metabolite, were examined for their association with food intake at baseline and with MetS at endpoint. Five metabolites were associated with microbiome diversity and replicated in the independent sample. Higher intakes of fruit and whole grains were associated with higher levels of hippurate cross-sectionally and longitudinally. An increasing hippurate trend was associated with reduced odds of having MetS (OR: 0.795[0.082]; P = 0.026). These data add further weight to the key role of the microbiome as a potential mediator of the impact of dietary intake on metabolic status and health.

ARTICLE Cytoglobin regulates blood pressure and vascular tone through nitric oxide metabolism in the vascular wall

Article

Full-text available

May 2017

The identity of the specific nitric oxide dioxygenase (NOD) that serves as the main in vivo regulator of O 2-dependent NO degradation in smooth muscle remains elusive. Cytoglobin (Cygb) is a recently discovered globin expressed in fibroblasts and smooth muscle cells with unknown function. Cygb, coupled with a cellular reducing system, efficiently regulates the rate of NO consumption by metabolizing NO in an O 2-dependent manner with decreased NO consumption in physiological hypoxia. Here we show that Cygb is a major regulator of NO degradation and cardiovascular tone. Knockout of Cygb greatly prolongs NO decay, increases vascular relaxation, and lowers blood pressure and systemic vascular resistance. We further demonstrate that downregulation of Cygb prevents angiotensin-mediated hypertension. Thus, Cygb has a critical role in the regulation of vascular tone and disease. We suggest that modulation of the expression and NOD activity of Cygb represents a strategy for the treatment of cardiovascular disease.

Untangling the relationship between diet and visceral fat mass through blood metabolomics and gut microbiome profiling

Article

Full-text available

Mar 2017
INT J OBESITY

Background/objectives: Higher visceral fat mass (VFM) is associated with an increased risk for developing cardio-metabolic diseases. The mechanisms by which an unhealthy diet pattern may influence VF development has yet to be examined through cutting-edge multi-omic methods. Therefore, our objective was to examine the dietary influences on VFM and identify gut microbiome and metabolite profiles that link food intakes to VFM. Subjects/methods: In 2218 twins with VFM, food intake and metabolomics data available we identified food intakes most strongly associated with VFM in 50% of the sample, then constructed and tested the 'VFM diet score' in the remainder of the sample. Using linear regression (adjusted for covariates, including BMI and total fat mass) we investigated associations between the VFM diet score, the blood metabolomics profile and the faecal microbiome (n=889), and confirmed these associations with VFM. We replicated top findings in monozygotic (MZ) twins discordant (⩾1 s.d. apart) for VFM, matched for age, sex and the baseline genetic sequence. Results: Four metabolites were associated with the VFM diet score and VFM: hippurate, alpha-hydroxyisovalerate, bilirubin (Z,Z) and butyrylcarnitine. We replicated associations between VFM and the diet score (Beta[s.e.]: 0.281[0.091]; P=0.002), butyrylcarnitine (0.199[0.087]; P=0.023) and hippurate (-0.297[0.095]; P=0.002) in VFM-discordant MZ twins. We identified a single species, Eubacterium dolichum to be associated with the VFM diet score (0.042[0.011], P=8.47 × 10(-5)), VFM (0.057[0.019], P=2.73 × 10(-3)) and hippurate (-0.075[0.032], P=0.021). Moreover, higher blood hippurate was associated with elevated adipose tissue expression neuroglobin, with roles in cellular oxygen homeostasis (0.016[0.004], P=9.82 × 10(-6)). Conclusion: We linked a dietary VFM score and VFM to Eubacterium dolichum and four metabolites in the blood. In particular, the relationship between hippurate, a metabolite derived from microbial metabolism of dietary polyphenols, and reduced VFM, the microbiome and increased adipose tissue expression of neuroglobin provides potential mechanistic insight into the influence of diet on VFM.International Journal of Obesity accepted article preview online, 15 March 2017. doi:10.1038/ijo.2017.70.

Cytoglobin: a potential marker for adipogenic differentiation in preadipocytes in vitro

Article

Full-text available

Feb 2017
CYTOTECHNOLOGY

Obesity, mainly characterized by the excess fat storage, is a global health problem resulting in serious morbidity and mortality. Identification of molecular mechanisms in adipogenic differentiation pathway might lead to development of new strategies for diagnosis, prevention and therapy of obesity and associated diseases. Discovery of new genes and proteins in the differentiation pathway could help to understand the key specific regulators of the adipogenesis. Cytoglobin (Cygb), identified as a new globin family member protein, is expressed in various tissues. Although its interaction with oxygen and nitric oxide indicates the potential role in antioxidant pathways, the exact role remains unclear. In the current study, expression level of Cygb was determined in proliferating and differentiating 3T3-F442A cells by gene expression and protein expression analysis. Results revealed that Cygb expression up-regulated in differentiated cells in parallel with adipogenic differentiation markers; PPARγ, CEBPα and FABP4 expressions. Besides, Cygb overexpression in preadipocytes contributed to the adipogenic differentiation as verified by detection of higher lipid droplets and increased PPARγ, CEBPα and FABP4 expressions with respect to control cells. These findings will shed light on the unknown roles of Cygb in adipogenesis and obesity.

Biomarkers of oxidative and nitro-oxidative stress: conventional and novel approaches

Article

Full-text available

Nov 2016
BRIT J PHARMACOL

The concept of oxidative stress (OS) that connects altered redox biology with various diseases was introduced 30 years ago and has generated intensive research over the past two decades. Whereas it is now commonly accepted that macromolecule oxidation in response to ROS is associated with a variety of pathologies, the emergence of NO as a key regulator of redox signalling has led to the discovery of the pathophysiological significance of reactive nitrogen species (RNS). RNS can elicit various modifications of macromolecules and lead to nitrative or nitro-OS. In order to investigate oxidative and nitro-OS in human and in live animal models, circulating biomarker assays have been developed. This article provides an overview of key biomarkers used to assess lipid peroxidation and NO/NO2 signalling, thereby stressing the necessity to analyse several OS biomarkers in relation to the overall (aerobic) metabolism and health condition of patients. In addition, the potential interest of heart rate variability as the non-invasive integrative biomarker of OS is discussed. Linked articles: This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Brain globins in physiology and pathology

Article

Full-text available

Oct 2016

Globins are globular proteins for either transport or storage of oxygen which are critical for cellular metabolism. Four globins have been identified in rodent and human brains. Among them, neuroglobin, cytoglobin and hemoglobin chains are constitutively expressed in normal brain, while myoglobin is only expressed in some neurological disorders. Studies on the molecular structure, expression and functional features of these brain globins indicated that they may play crucial roles in maintenance of neural cell survival and activity, including neurons and astrocytes. Their regulation in neurological disorders may help thoroughly understand initiation and progression of ischemia, Alzheimer′s disease and glioma, etc. Elucidation of the brain globin functions might remarkably improve medical strategies that sustain neurological homeostasis and treat neurological diseases. Here the expression pattern and functions of brain globins and their involvement in neurological disorders are reviewed.

Evaluating the Hypoxia Response of Ruffe and Flounder Gills by a Combined Proteome and Transcriptome Approach

Article

Full-text available

Aug 2015
PLOS ONE

Hypoxia has gained ecological importance during the last decades, and it is the most dramatically increasing environmental factor in coastal areas and estuaries. The gills of fish are the prime target of hypoxia and other stresses. Here we have studied the impact of the exposure to hypoxia (1.5 mg O2/l for 48 h) on the protein expression of the gills of two estuarine fish species, the ruffe (Gymnocephalus cernua) and the European flounder (Platichthys flesus). First, we obtained the transcriptomes of mixed tissues (gills, heart and brain) from both species by Illumina next-generation sequencing. Then, the gill proteomes were investigated using two-dimensional gel electrophoresis and mass spectrometry. Quantification of the normalized proteome maps resulted in a total of 148 spots in the ruffe, of which 28 (18.8%) were significantly regulated (> 1.5-fold). In the flounder, 121 spots were found, of which 27 (22.3%) proteins were significantly regulated. The transcriptomes were used for the identification of these proteins, which was successful for 15 proteins of the ruffe and 14 of the flounder. The ruffe transcriptome dataset comprised 87,169,850 reads, resulting in an assembly of 72,108 contigs (N50 = 1,828 bp). 20,860 contigs (26.93%) had blastx hits with E < 1e-5 in the human sequences in the RefSeq database, representing 14,771 unique accession numbers. The flounder transcriptome with 78,943,030 reads assembled into 49,241 contigs (N50 = 2,106 bp). 20,127 contigs (40.87%) had a hit with human proteins, corresponding to 14,455 unique accession numbers. The regulation of selected genes was confirmed by quantitative real-time RT-PCR. Most of the regulated proteins that were identified by this approach function in the energy metabolism, while others are involved in the immune response, cell signalling and the cytoskeleton.

Thyroid hormone modulates neuroglobin and cytoglobin in rat brain

Article

Full-text available

Sep 2015
METAB BRAIN DIS

Thyroid hormones (THs) are essential and crucial for brain development, playing a role in growth and differentiation. Two globins named neuroglobin (Ngb) and cytoglobin (Cygb) are located in the brain, and each one has different distribution and function: They seem to have similar action by providing O2 for respiratory chain, and detoxification of reactive oxygen species (ROS) and nitric oxide (NO) protecting tissues against irreversible lesions. We aimed to investigate the influence of thyroid state in Ngb and Cygb metabolism in different brain regions and evaluate their responses in cerebellum, hippocampus and cerebral cortex (hereafter called as cortex) after supraphysiological doses at different time points of TH administration. Experiments were carried out in rats, divided in eight experimental groups Control (C), thyroidectomy (Tx), and thyroidectomy treated with jugular intravenous injection (i.v). T3 (100 μl/100 g) injection and sacrificed after 30, 60, 120 min and 6, 12 and 24 h. In cortex, we found increase in Ngb gene and protein expression in different time points compared to C group, however Cygb gene and protein expression were decreased. In hippocampus, Ngb and Cygb protein expression increased 24 h after i.v. T3 injection in comparison to Tx. In cerebellum, we found increased Ngb gene expression after 120 min, 6, 12 and 24 h after T3 administration compared to Tx, and in contrast, protein expression was found to be significantly increased only 12 and 24 h compared to Tx. Ngb and Cygb expression in brain is influenced by thyroid hormone state both by its lack or excess.

Cytoglobin as a Biomarker in Cancer: Potential Perspective for Diagnosis and Management

Article

Full-text available

Aug 2015
BMRI

The search for biomarkers to detect the earliest glimpse of cancer has been one of the primary objectives of cancer research initiatives. These endeavours, in spite of constant clinical challenges, are now more focused as early cancer detection provides increased opportunities for different interventions and therapies, with higher potential for improving patient survival and quality of life. With the progress of the omics technologies, proteomics and metabolomics are currently being used for identification of biomarkers. In this line, cytoglobin (Cygb), a ubiquitously found protein, has been actively reviewed for its functional role. Cytoglobin is dynamically responsive to a number of insults, namely, fibrosis, oxidative stress, and hypoxia. Recently, it has been reported that Cygb is downregulated in a number of malignancies and that an induced overexpression reduces the proliferative characteristics of cancer cells. Thus, the upregulation of cytoglobin can be indicative of a tumour suppressor ability. Nevertheless, without a comprehensive outlook of the molecular and functional role of the globin, it will be most unlikely to consider cytoglobin as a biomarker for early detection of cancer or as a therapeutic option. This review provides an overview of the proposed role of cytoglobin and explores its potential functional role as a biomarker for cancer and other diseases.

Cytoglobin expression in the hepatic stellate cell line HSC-T6 is regulated by extracellular matrix proteins dependent on FAK-signalling

Article

Full-text available

Aug 2015

Fibrosis is a physiological response to cellular injury in the liver and is mediated by the activation of hepatic stellate cells resulting in the replacement of hepatocytes with extracellular matrix comprised principally of collagen 1 to form a hepatic scar. Although the novel hexaco-ordinated globin cytoglobin was identified in activated hepatic stellate cells more than 10 years ago, its role in stellate cell biology and liver fibrosis remains enigmatic. In the current study, we investigated the role of different extracellular matrix proteins in stellate cell proliferation, activation (alpha smooth muscle actin expression and retinoic acid uptake) and cytoglobin expression. Our results demonstrate that cytoglobin expression is correlated with a more quiescent phenotype of stellate cells in culture and that cytoglobin is regulated by the extracellular matrix through integrin signalling dependent on activation of focal adhesion kinase. Although further studies are required, we provide evidence that cytoglobin is a negative regulator of stellate cell activation and therefore may represent a novel target for anti-fibrotic treatments in the future.

High Altitude Disease: Consequences of Genetic and Environmental Interactions

Article

High altitude disease (HAD) is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude. Millions of people who live at, or ascend to, altitudes above 2,500 m, are at risk for acute mountain sickness (AMS) and chronic mountain sickness (CMS). Among these populations, there are distinct patterns of adaptation to the environment, lowlanders are more susceptible to HAD than highlanders when they are exposured to hypoxia, Andean highlanders have higher incidence rate of HAD than Tibetans and Sherpas. People originating from the same sea level have different response to hypoxia. These situations showed that the incidence of HAD has a certain genetic background. With the development of modern research techniques, there is more and more evidences that indicates that the pathogenesis of HAD is associated with some mutant form of hypoxia-related genes, number and function of the genes encoding protein, such as HIF1A,EPO,EDN1,NOS3, and also associated with human leukocyte antigen (HLA)(define it) system, oxygen-carrying proteins and other genes. Although numerous molecular genetic linkage and association studies have been conducted to explain the pathology of high altitude disease, none are complete. With the availability of large scale DNA data sets, we will be able to identify more potential hypoxia related genes, and elucidate the genetics of high altitude diseases.

The Effects of CoCl2 on HIF-1α Protein under Experimental Conditions of Autoprogressive Hypoxia Using Mouse Models

Article

Full-text available

Jun 2014

It is well known that cobalt chloride (CoCl2) can enhance the stability of hypoxia-inducible factor (HIF)-1α. The aim of this study is to detect the effect of CoCl2 on the hypoxia tolerance of mice which were repeatedly exposed to autoprogressive hypoxia. Balb/c mice were randomly divided into groups of chemical pretreatment and normal saline (NS), respectively injected with CoCl2 and NS 3 h before exposure to hypoxia for 0 run (H0), 1 run (H1), and 4 runs (H4). Western Blot, electrophoretic mobility shift assay (EMSA), extracellular recordings population spikes in area cornus ammonis I (CA 1) of mouse hippocampal slices and real-time were used in this study. Our results demonstrated that the tolerance of mice to hypoxia, the changes of HIF-1α protein level and HIF-1 DNA binding activity in mice hippocampus, the mRNA level of erythropoietin (EPO) and vascular endothelial growth factor (VEGF), and the disappearance time of population spikes of hippocampal slices were substantially different between the control group and the CoCl2 group. Over-induction of HIF-1α by pretreatment with CoCl2 before hypoxia did not increase the hypoxia tolerance.

Function and evolution of vertebrate globins

Article

Full-text available

May 2014
ACTA PHYSIOL

Globins are heme-proteins that bind O2 and thus play an important role in the animal's respiration and oxidative energy production. However, globins may also have other functions such as the decomposition or production of NO, the detoxification of reactive oxygen species, or intracellular signalling. In addition to the well-investigated haemoglobins and myoglobins, genome sequence analyses have led to the identification of six further globin types in vertebrates: androglobin, cytoglobin, globin E, globin X, globin Y and neuroglobin. Here, we review the present state of knowledge on the functions, the taxonomic distribution and evolution of vertebrate globins, drawing conclusions about the functional changes underlying present-day globin diversity. This article is protected by copyright. All rights reserved.

Esenciales en biología, patobiología y bioclínica del oxido nítrico

Article

Full-text available

Mar 2009

Nitric Oxid is a multifunctional regulator, it is important for several process including inflammation, vessels regulation, intracellular signaling, apoptosis and carcinogenesis. A failure in its synthesis or bioaviability is the principal fact of many diseases. Understanding the mechanisms of the nitric oxid at a tissue and celular level will allow to develop new therapies to balance its in vivo effects. This review will mention the main findings of this diatomic gas and its biologic dynamic

Neuroglobins, Pivotal Proteins Associated with Emerging Neural Systems and Precursors of Metazoan Globin Diversity

Article

Full-text available

Jan 2013
J BIOL CHEM

Neuroglobins, previously thought to be restricted to vertebrate neurons, were detected in the brain of a photosymbiotic acoel, Symsagittifera roscoffensis, and in neurosensory cells of the jellyfish Clytia hemisphaerica. For the neuroglobin of S. roscoffensis, a member of a lineage that originated either at the base of the bilateria or of the deuterostome clade, we report the ligand binding properties, crystal structure at 2.3 Å, and brain immunocytochemical pattern. We also describe in situ hybridizations of two neuroglobins specifically expressed in differentiating nematocytes (neurosensory cells) and in statocytes (ciliated mechanosensory cells) of C. hemisphaerica, a member of the early branching animal phylum cnidaria. In silico searches using these neuroglobins as queries revealed the presence of previously unidentified neuroglobin-like sequences in most metazoan lineages. Because neural systems are almost ubiquitous in metazoa, the constitutive expression of neuroglobin-like proteins strongly supports the notion of an intimate association of neuroglobins with the evolution of animal neural systems and hints at the preservation of a vitally important function. Neuroglobins were probably recruited in the first protoneurons in early metazoans from globin precursors. Neuroglobins were identified in choanoflagellates, sponges, and placozoans and were conserved during nervous system evolution. Because the origin of neuroglobins predates the other metazoan globins, it is likely that neuroglobin gene duplication followed by co-option and subfunctionalization led to the emergence of globin families in protostomes and deuterostomes (i.e. convergent evolution).

Neuroglobin and cytoglobin

Article

Full-text available

Mar 2011

The globin family has long been defined by myoglobin and hemoglobin, proteins with the functions of oxygen storage and transportation, respectively. Recently, two new members of this family were discovered: neuroglobin present in neurons and retinal cells and cytoglobin found in various types of tissue. The increased expression of these proteins in hypoxic conditions first suggested a role in oxygen supply. However structural and functional differences, such as the hexacoordinated heme, a high autoxidation rate and different concentrations between different cellular types, have dismissed this hypothesis. The protective role of these globins has already been established. In vitro and in vivo studies have demonstrated increased survival of neurons under stress in the presence of neuroglobin and increased resistance to neurodegenerative diseases. However the mechanism remains unknown. Functions, including detoxification of nitric oxide, free radical scavenging and as an antioxidant and signaling of apoptosis, have also been suggested for neuroglobin and an antifibrotic function for cytoglobin.

Early life dietary exposures mediate persistent shifts in the gut microbiome and visceral fat metabolism

Article

Jul 2022

Introduction: In utero dietary exposures are linked to the development of metabolic syndrome in adult offspring. These dietary exposures can potentially impact gut microbial composition and offspring metabolic health. Methods: Female BALB/c mice were administered a lard, lard+flaxseed oil, high sugar, or control diet 4-weeks prior to mating, throughout mating, pregnancy, and lactation. Daughters were offered low-fat control diet at weaning. Fecal 16S sequencing was performed. Untargeted metabolomics was performed on visceral adipose tissue (VAT) of adult daughters. Immunohistochemistry was used to determine adipocyte size, VAT collagen deposition, and macrophage content. Hippurate was administered via weekly IP injections and VAT Smad2, TGF-β and COL1A protein expression was quantified by western blot. Results: Lard diet exposure was associated with elevated body and VAT weight and dysregulated glucose metabolism. Lard+flaxseed attenuated these effects. Lard diet exposures were associated with increased adipocyte diameter and VAT macrophage count. Lard+flaxseed reduced adipocyte diameter and fibrosis compared to lard diet. Hippurate-associated bacteria were influenced by lard vs. lard+flaxseed exposures that persisted to adulthood. VAT hippurate was increased in lard+flaxseed compared to lard diet. Hippurate supplementation mitigated VAT inflammation and fibrosis-associated protein levels. Discussion: Maternal high-fat lard diet consumption resulted in long-term metabolic and gut microbiome programming in offspring, impacted VAT inflammation and fibrosis, and was associated with reduced VAT hippurate content. Hippurate modifies VAT TGF-β signaling to reduce fibrosis and inflammation. These data suggest that detrimental effects of early life high fat lard diet exposure can be attenuated by dietary omega-3 polyunsaturated fatty acid supplementation.

Utility of fluorescent heme analogue ZnPPIX to monitor conformational heterogeneity in vertebrate hexa-coordinate globins

Article

Jan 2019

Here we report preparation and photo-physical characterization of hexa-coordinate vertebrate globins, human neuroglobin (hNgb) and cytoglobin (Cygb), with the native iron protoporphyrin IX (FePPIX) cofactor replaced by a fluorescent isostructural analogue zinc protoporphyrin IX (ZnPPIX). To facilitate insertion of ZnPPIX into hexa-coordinate globins, apoproteins prepared by a butanone extraction were unfolded by addition of GuHCl and subsequently slowly refolded in the presence of ZnPPIX. The absorption/emission spectra of ZnPPIX reconstituted hCygb are similar to those observed for ZnPPIX reconstituted myoglobin whereas absorption and emission spectra of ZnPPIX reconstituted hNgb are blue shifted by ~ 2 nm. Different steady state absorption and emission properties of ZnPPIX incorporated in hCygb and hNgb are consistent with distinct hydrogen bonding interactions between ZnPPIX and the globin matrix. The fluorescence lifetime of ZnPPIX in hexa-coordinate globins is bimodal pointing towards increased heterogeneity of the heme binding cavity in hCygb and hNgb. ZnPPIX reconstituted Ngb binds to cytochrome c with the same affinity as reported for the native protein, suggesting that fluorescent analogues of Cygb and Ngb can be readily employed to monitor interactions between vertebrate hexa-coordinate globins and other proteins.

Neuroprotection in glaucoma: recent advances and clinical translation: Neuroprotection in glaucoma

Article

Jun 2018

Intraocular pressure (IOP) reduction is currently the only evidence‐based treatment strategy for glaucoma. However, IOP control in some individuals is challenging. Despite optimal treatment, a significant proportion of individuals will progress, with loss of visual field, loss of driving vision, and impaired quality of life. A new modality that could augment current treatment and reduce the rate of neurodegeneration to preserve vision throughout life would be a major breakthrough. A vast number of studies have reported effective neuroprotection in animal models of glaucoma; however, translation to the clinic remains a major hurdle. Herein, we explore the therapeutic advancements in non‐IOP dependent neuroprotection research based upon potential pathogenic mechanisms and propose strategies to improve the clinical translation of neuroprotective research in glaucoma. This article is protected by copyright. All rights reserved.

Maternal cytoglobin (CYGB) serum levels in normal and preeclamptic pregnancies

Article

Dec 2017

Objective: To investigate cytoglobin levels in women with preeclampsia and women with uncomplicated pregnancies. Materials and methods: A cross-sectional study including 26 pregnant women complicated with early onset preeclampsia (EO-PE) and 26 pregnant women complicated with late onset preeclampsia (LO-PE) were recruited for the study group. Twenty-seven healthy pregnant women selected randomly were included into the control group. The serum CYGB concentrations were measured using an enzyme-linked immunosorbent assay. Results: Gestational age at delivery and mean birth weight were significantly lower in the preeclampsia groups than in the control group and were found to be the lowest in the EO-PE group (p < 0.001). Serum CYGB levels were significantly higher in the EO-PE and LO-PE groups as compared with the control group (9.99 (6.08) ng/ml (EOPE), 10.04 (7.04) ng/ml (LOPE) versus 2.84 (0.82) ng/ml), (p < 0.001). However, a significant difference was not found between the EO-PE and LO-PE groups regarding CYGB levels (p = 1.000). Conclusions: Serum CYGB levels were significantly higher in patients with EO-PE and LO-PE as compared to healthy pregnant women.

Dissecting the 17β‐estradiol pathways necessary for Neuroglobin anti‐apoptotic activity in breast cancer

Article

Dec 2017
J CELL PHYSIOL

Neuroglobin (NGB) is a relatively recent discovered monomeric heme-protein, which behave in neurons as a sensor of injuring stimuli including oxidative stress, hypoxia, and neurotoxicity. In addition, the anti-apoptotic activity of overexpressed NGB has been reported both in neurons and in cancer cell lines. We recently demonstrated that, NGB functions as a compensatory protein of the steroid hormone 17β-estradiol (E2) protecting cancer cells against the apoptotic death induced by oxidative stress. However, as far we known, the E2-induced signaling pathways at the root of NGB over-expression and mitochondrial re-localization in breast cancer cells is still elusive. By using a kinase screening library, here, we report that i) There is a strong positive correlation between NGB and ERα expression and activity in breast cancer cells. ii) The E2-activated phosphatidyl-inositol 3 kinase (PI3K)/protein kinase B (AKT) and protein kinase C (PKC) pathways are necessary to modulate the NGB protein levels. iii) The E2-induced persistent activation of AKT drive NGB to mitochondria. iv) Reactive oxygen species (ROS)-inducing compounds activating rapidly and transiently AKT does not affect the NGB mitochondrial level. v) High level of NGB into mitochondria are necessary for the pro-survival and anti-apoptotic effect of this globin in cancer cells. As a whole, these results underline the E2 triggered pathways in E2-responsive breast cancer cells that involve NGB as a compensatory protein devoted to cancer cell survival. This article is protected by copyright. All rights reserved

A novel function of neuroglobin for neuroregeneration in mice after optic nerve injury

Article

Sep 2017

Neuroglobin (Ngb) is a recently discovered heme protein in the vertebrate brain that can bind to oxygen molecules. Mammalian Ngb plays a crucial role in neuroprotection under conditions of oxidative stress. To investigate other potential functions of Ngb, we investigated the mouse retinal Ngb system following optic nerve injury. In the retina of control mice, Ngb immunoreactivity was limited to the retinal ganglion cell (RGC) layer, and this immunoreactivity rapidly decreased to less than 50% of the control level 5 days after optic nerve injury. On the basis of this decrease, we designed in vivo experiments with enhanced expression of Ngb using adult mouse retina. The enhanced expression of Ngb was achieved by injecting chimeric human Ngb protein, which included the cell membrane-penetrating module of fish Ngb. One-day pretreatment with chimeric Ngb increased immunoreactivity levels of Ngb two-fold in mouse RGCs and increased the number of surviving RGCs three-fold by 14 days after optic nerve injury compared with vehicle controls. Furthermore, in the mouse retinas showing enhanced Ngb expression, several regenerating central optic axons exhibited outgrowth and were found to pass through the nerve crush site 14 days after nerve injury. No such regenerating optic axons were observed in the control mouse optic nerve during the same time frame. The data obtained from in vivo experiments strongly indicate that mammalian Ngb has neuroprotective and neuroregenerative properties.

Neuroglobin and friends

Article

Jul 2017
J MOL RECOGNIT

In the year 2000, the third member of the globin family was discovered in human and mouse brain and named neuroglobin (Ngb). Neuroglobin overexpression significantly protects both heart and brain from hypoxic/ischemic and oxidative stress-related insults, whereas decreased Ngb levels lead to an exacerbation of tissue injuries. Moreover, Ngb overexpression protects neurons from mitochondrial dysfunctions and neurodegenerative disorders such as Alzheimer disease; however, it facilitates the survival of cancer cells. Neuroglobin, representing a switch point for cell death and survival, has been reported to recognize a number of proteins involved in several metabolic pathways including ionic homeostasis maintenance, energy metabolism, mitochondrial function, and cell signaling. Here, the recognition properties of Ngb are reviewed to highlight its roles in health and disease.

Neuroglobin: A Novel Target for Endogenous Neuroprotection

Chapter

Mar 2012

Augmentation of endogenous protective mechanisms has been thought to be promising strategies to develop new therapies against stroke. Neuroglobin (Ngb) is a tissue oxygen-binding globin that is highly and specifically expressed in brain neurons. Accumulating evidences have proved Ngb is a unique endogenous neuroprotective molecule against hypoxic/ischemic insults in cultured neurons and in stroke animals, which strongly suggest that development of pharmacological strategies that upregulate endogenous Ngb expression may lead to a novel therapeutic approach for stroke intervention. In this chapter, recent experimental findings from our laboratory and others in understanding Ngb’s biological function, gene expression regulation, and neuroprotective mechanisms are summarized. We also propose strategies to identify small molecules that upregulate endogenous Ngb for neuroprotection against stroke and related neurological disorders. Briefly, the strategies comprise two translational features. First, we will establish both mouse and human Ngb gene activation reporter stable cell lines to ensure that only compounds capable of activating both mouse and human Ngb promoters will be selected for further testing. Second, validation is the key component of any single step in drug screening and therapeutic development processes.

Absence of cytoglobin promotes multiple organ abnormalities in aged mice

Article

Full-text available

May 2016

Cytoglobin (Cygb) was identified in hepatic stellate cells (HSCs) and pericytes of all organs; however, the effects of Cygb on cellular functions remain unclear. Here, we report spontaneous and age-dependent malformations in multiple organs of Cygb−/− mice. Twenty-six percent of young Cygb−/− mice (<1 year old) showed heart hypertrophy, cystic disease in the kidney or ovary, loss of balance, liver fibrosis and lymphoma. Furthermore, 71.3% (82/115) of aged Cygb−/− mice (1–2 years old) exhibited abnormalities, such as heart hypertrophy and cancer development in multiple organs; by contrast, 5.8% (4/68) of aged wild-type (WT) mice had abnormalities (p < 0.0001). Interestingly, serum and urine analysis demonstrated that the concentration of nitric oxide metabolites increased significantly in Cygb−/− mice, resulting in an imbalance in the oxidative stress and antioxidant defence system that was reversed by NG-monomethyl-L-arginine treatment. A senescent phenotype and evidence of DNA damage were found in primary HSCs and the liver of aged Cygb−/− mice. Moreover, compared with HSC+/+, HSC−/− showed high expression of Il-6 and chemokine mRNA when cocultured with mouse Hepa 1–6 cells. Thus, the absence of Cygb in pericytes provokes organ abnormalities, possibly via derangement of the nitric oxide and antioxidant defence system and through accelerated cellular senescence.

Neuroglobin - A potential biological marker of retinal damage induced by LED light

Article

Apr 2014

Neuroglobin (NGB), a protein highly expressed in the retina, has been shown to be up-regulated to protect neurons from hypoxic and ischemic injuries. It exhibits neuroprotective functions and plays an important role in the survival of neurons. Recent studies show that LED white light emitted significant amounts of blue light (short-wavelength), which may be harmful to retinal cells, but the studies about biomarker for evaluating the damage from LED white light are still insufficient. In our study, we found that NGB levels in the retina showed a 2-fold increase and peaked at 1 hour after a 1-hour exposure to blue light (453 nm) which did not cause damage to the retina. However, retinal damage was observed after 2 hours of blue light irradiation, which induced an approximate 7-fold increase of neuroglobin levels as confirmed by Western blot and RT-PCR analysis. Immunofluorescence study demonstrated that NGB was predominantly up-regulated in the ganglion cell layer (GCL), plexiform layer (PL) and photoreceptor layer (PRL). We also examined neuroglobin mRNA and protein expression in damaged retina induced by light of other wavelengths given equal photon fluxes. The LED red light (625 nm), green light (527 nm) and blue light (453 nm) increased the expression of NGB and caused TUNEL positive cells, especially in the blue light group. In addition, a negative correlation between NGB and rhodopsin was observed. These findings suggested that there was a correlation between NGB expression and the severity of the retinal damage, indicating NGB's potential function as a biological marker of retinal damage induced by LED light.

How Biology Handles Nitrite

Article

Full-text available

Apr 2014
CHEM REV

Nitrite is one of the players in the broad nitrogen biogeochemical cycle. This nitrogen oxo-anion is involved in key pathways crucial to life on Earth and to the planetary recycling of nitrogen. The global aim is to review the present functional, structural, and mechanistic knowledge of nitrite reduction/oxidation, to assess in what extent we understand how nitrite is handled by living organisms. Nitrite formation is outside the scope of this Review. This knowledge is essential for the comprehension of the global nitrogen biochemical cycle and, consequently, for the comprehension of the impressive changes the human activities are introducing in the cycle. However, under most physiological conditions, glutamate dehydrogenase catalyzes instead the reverse reaction, yielding ammonium in amino acid catabolism.

Hematopoietic Stem/Progenitor Cells Express Myoglobin and Neuroglobin: Adaptation to Hypoxia or Prevention from Oxidative Stress?

Article

May 2014
STEM CELLS

Oxidative metabolism and redox signalling prove to play a decisional role in controlling adult hematopoietic stem/progenitor cells (HSPCs) biology. However, HSPCs reside in a hypoxic bone marrow microenvironment raising the question of how oxygen metabolism might be ensued. In this study we provide for the first time novel functional and molecular evidences that human HSPCs express myoglobin (Mb) at level comparable with that of a muscle-derived cell line. Optical spectroscopy and oxymetry enabled to estimate an O2 -sensitive heme-containing protein content of ≈ 180 ng globin/10(6) HSPC and a P50 ≈ 3 μM O2 . Noticeably, expression of Mb mainly occurs through a HIF-1-induced alternative transcript (Mb-V/Mb-N =35 ±15, P<0.01). A search for other Mb-related globins unveiled significant expression of neuroglobin (Ngb) but not of cytoglobin. Confocal microscopy immune-detection of Mb in HSPCs strikingly revealed nuclear localization in cell subsets expressing high level of CD34 (nuclear/cytoplasmic Mb ratios 1.40 ±0.02 vs. 0.85 ±0.05, P< 0.01) whereas Ngb was homogeneously distributed in all the HSPC population. Dual-color fluorescence flow cytometry indicated that while the Mb content was homogeneously distributed in all the HSPC subsets that of Ngb was two-fold higher in more immature HSPC. Moreover, we show that HSPCs exhibit a hypoxic nitrite reductase activity releasing NO consistent with described non-canonical functions of globins. Our finding extends the notion that Mb and Ngb can be expressed in non-muscle and non-neural contexts respectively and is suggestive of a differential role of Mb in HSPC in controlling oxidative metabolism at different stages of commitment. Stem Cells 2014.

[Recent advances in study of neuroglobin expression in retinal diseases]

Article

Apr 2013

Neuroglobin (NGB) is widely exists in the retina and predominantly expressed in the plexiform layers and the inner segments. The physiological roles of NGB may include transportation of oxygen, protection against ischemia/hypoxia injury and oxidative stress, function as a redox-coupled sensor regulating the G-protein coupled transduction pathway, protection against neuronal apoptosis, and working as a terminal oxidase. Based on the function and distribution of NGB and the etiology and pathogenesis of retinal degeneration; it is possible that NGB may play a role in the development of retinal degeneration.

Hypoxia as target for tissue specific gene therapy

Article

Jun 2013

Hypoxia is a hallmark of various ischemic diseases such as ischemic heart disease, ischemic limb, ischemic stroke, and solid tumors. Gene therapies for these diseases have been developed with various therapeutic genes including growth factors, anti-apoptotic genes, and toxins. However, non-specific expression of these therapeutic genes may induce dangerous side effects in the normal tissues. To avoid the side effects, gene expression should be tightly regulated in an oxygen concentration dependent manner. The hypoxia inducible promoters and enhancers have been evaluated as a transcriptional regulation tool for hypoxia inducible gene therapy. The hypoxia inducible UTRs were also used in gene therapy for spinal cord injury as a translational regulation strategy. In addition to transcriptional and translational regulations, post-translational regulation strategies have been developed using the HIF-1α ODD domain. Hypoxia inducible transcriptional, translational, and post-translational regulations are useful for tissue specific gene therapy of ischemic diseases. In this review, hypoxia inducible gene expression systems are discussed and their applications are introduced.

A Gene-Environment Study of Cytoglobin in the Human and Rat Hippocampus

Article

Full-text available

May 2013
PLOS ONE

Cytoglobin (Cygb) was discovered a decade ago as the fourth vertebrate heme-globin. The function of Cygb is still unknown, but accumulating evidence from in vitro studies point to a putative role in scavenging of reactive oxygen species and nitric oxide metabolism and in vivo studies have shown Cygb to be up regulated by hypoxic stress. This study addresses three main questions related to Cygb expression in the hippocampus: 1) Is the rat hippocampus a valid neuroanatomical model for the human hippocampus; 2) What is the degree of co-expression of Cygb and neuronal nitric oxide synthase (nNOS) in the rat hippocampus; 3) The effect of chronic restraint stress (CRS) on Cygb and nNOS expression. Immunohistochemistry was used to compare Cygb expression in the human and rat hippocampi as well as Cygb and nNOS co-expression in the rat hippocampus. Transcription and translation of Cygb and nNOS were investigated using quantitative real-time polymerase chain reaction (real-time qPCR) and Western blotting on hippocampi from Flinders (FSL/FRL) rats exposed to CRS. Cygb expression pattern in the human and rat hippocampus was found to be similar. A high degree of Cygb and nNOS co-expression was observed in the rat hippocampus. The protein levels of nNOS and Cygb were significantly up-regulated in FSL animals in the dorsal hippocampus. In the ventral hippocampus Cygb protein levels were significantly up-regulated in the FSL compared to the FRL, following CRS. The rodent hippocampus can be used to probe questions related to Cygb protein localization in human hippocampus. The high degree of Cygb and nNOS co-expression gives support for Cygb involvement in nitric oxide metabolism. CRS induced Cygb and nNOS expression indicating that Cygb expression is stress responsive. Cygb and nNOS may be important in physiological response to stress.

Oral Glutamine Reduces Radiation Morbidity in Breast Conservation Surgery

Article

Feb 2013

This study examined the effect of oral glutamine (Gln) on radiation injury in breast cancer patients undergoing radiation therapy. The radiation injury was evaluated using Radiation Therapy Oncology Group (RTOG) scales. Cosmesis was scored. Blood Gln and glutathione (GSH) levels were determined. Serum protein profiling was determined using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). Patients receiving Gln scored significantly better in RTOG score than the patients receiving placebo. Cosmetic scores averaged excellent in the Gln group vs fair to good in the placebo group. Blood Gln and GSH levels were significantly higher in the Gln group vs the placebo group. Serum protein profiling with SELDI-TOF MS identified a novel Gln-responsive protein that showed amino acid similarity with myoglobin. These results suggest that Gln is an effective way to reduce radiation morbidity to breast cancer and is associated with the increased expression of a novel serum protein biomarker.

Neuroglobin and Cytoglobin expression in the human brain

Article

Nov 2012
BRAIN STRUCT FUNCT

Neuroglobin and Cytoglobin are new members of the heme-globin family. Both globins are primarily expressed in neurons of the brain and retina. Neuroglobin and Cytoglobin have been suggested as novel therapeutic targets in various neurodegenerative diseases based on their oxygen binding and cell protecting properties. However, findings in Neuroglobin-deficient mice question the endogenous neuroprotective properties. The expression pattern of Neuroglobin and Cytoglobin in the rodent brain is also in contradiction to a major role of neuronal protection. In a recent study, Neuroglobin was ubiquitously expressed and up-regulated following stroke in the human brain. The present study aimed at confirming our previous observations in rodents using two post-mortem human brains. The anatomical localization of Neuroglobin and Cytoglobin in the human brain is much like what has been described for the rodent brain. Neuroglobin is highly expressed in the hypothalamus, amygdale and in the pontine tegmental nuclei, but not in the hippocampus. Cytoglobin is highly expressed in the habenula, hypothalamus, thalamus, hippocampus and the pontine tegmental nuclei. We only detected a low expression of Neuroglobin and Cytoglobin in the cerebral cortex, while no expression in the cerebellar cortex was detectable. We provide a neuroanatomical indication for a different role of Neuroglobin and Cytoglobin in the human brain.

The Art of Tracking: The Origin of Science

Book

Full-text available

Apr 1990
S Afr Archaeol Bull

Louis Liebenberg

The art of tracking may have been the origin of science.

HIF-1 alpha is essential for myeloid cell-mediated inflammation

Article

Full-text available

May 2003
CELL

Cytoglobin/STAP, its unique localization in splanchnic fibroblast-like cells and function in organ fibrogenesis

Article

Full-text available

Dec 2003

Cytoglobin/stellate cell activation-associated protein (Cygb/STAP) consists of a new class of hexacoordinate globin superfamily, which was recently discovered by a proteome analysis on the rat hepatic stellate cells. Unlike haemoglobin, myoglobin, and neuroglobin, Cygb/STAP is ubiquitously expressed in several organs, although its detailed localization has not been clarified. Immunohistochemistry and immunoelectron microscopy revealed that Cygb/STAP is uniquely localized in fibroblast-like cells in splanchnic organs, namely the vitamin A-storing cell lineage, but neither in epithelial cells, endothelial cells, muscle cells, blood cells, macrophages, nor dermal fibroblasts. The expression of Cygb/STAP was upregulated in fibrotic lesions of the pancreas and kidney in which activated fibroblast-like cells or myofibroblasts are known to increase in number. In cultured hepatic stellate cells, Cygb/STAP expression was augmented by the stimulation with sera, platelet-derived growth factor-BB, and transforming growth factor- 1. Overexpression of Cygb/STAP in NIH 3T3 cells induced the cells to lessen migratory activities and increase the expression of collagen 1(I) mRNA. These results indicate that Cygb/STAP is a tissue globin uniquely localized in splanchnic fibroblastic cell lineage and may play a role in fibrotic organ disorder.Keywords: stellate cells, fibroblasts, vitamin A, collagen 1(I), PDGF, TGF , NIH 3T3 cells

Distinct Caspase Cascades Are Initiated in Receptor-Mediated and Chemical-Induced Apoptosis

Article

Full-text available

Feb 1999

Release of cytochrome c is important in many forms of apoptosis. Recent studies of CD95 (Fas/APO-1)-induced apoptosis have implicated caspase-8 cleavage of Bid, a BH3 domain-containing proapoptotic member of the Bcl-2 family, in this release. We now demonstrate that both receptor-induced (CD95 and tumor necrosis factor) and chemical-induced apoptosis result in a similar time-dependent activation of caspases-3, -7, -8, and -9 in Jurkat T cells and human leukemic U937 cells. In receptor-mediated apoptosis, the caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone (Z-VAD.FMK), inhibits apoptosis prior to commitment to cell death by inhibiting the upstream activator caspase-8, cleavage of Bid, release of mitochondrial cytochrome c, processing of effector caspases, loss of mitochondrial membrane potential, and externalization of phosphatidylserine. However, Z-VAD.FMK inhibits chemical-induced apoptosis at a stage after commitment to cell death by inhibiting the initiator caspase-9 and the resultant postmitochondrial activation of effector caspases. Cleavage of Bid but not release of cytochromec is blocked by Z-VAD.FMK demonstrating that in chemical-induced apoptosis cytochrome c release is caspase-independent and is not mediated by activation of Bid. We propose that caspases form an integral part of the cell death-inducing mechanism in receptor-mediated apoptosis, whereas in chemical-induced apoptosis they act solely as executioners of apoptosis.

Biochemical Characterization and Ligand Binding Properties of Neuroglobin, a Novel Member of the Globin Family

Article

Full-text available

Oct 2001

Neuroglobin is a recently discovered member of the globin superfamily that is suggested to enhance the O2 supply of the vertebrate brain. Spectral measurements with human and mouse recombinant neuroglobin provide evidence for a hexacoordinated deoxy ferrous (Fe2+) form, indicating a His-Fe2+-His binding scheme. O2 or CO can displace the endogenous protein ligand, which is identified as the distal histidine by mutagenesis. The ferric (Fe3+) form of neuroglobin is also hexacoordinated with the protein ligand E7-His and does not exhibit pH dependence. Flash photolysis studies show a high recombination rate (k on) and a slow dissociation rate (k off) for both O2 and CO, indicating a high intrinsic affinity for these ligands. However, because the rate-limiting step in ligand combination with the deoxy hexacoordinated form involves the dissociation of the protein ligand, O2 and CO binding is suggested to be slowin vivo. Because of this competition, the observed O2 affinity of recombinant human neuroglobin is average (1 torr at 37 °C). Neuroglobin has a high autoxidation rate, resulting in an oxidation at 37 °C by air within a few minutes. The oxidation/reduction potential of mouse neuroglobin (E′o = −129 mV) lies within the physiological range. Under natural conditions, recombinant mouse neuroglobin occurs as a monomer with disulfide-dependent formation of dimers. The biochemical and kinetic characteristics are discussed in view of the possible functions of neuroglobin in the vertebrate brain.

β-Adrenergic receptor stimulation and adenoviral overexpression of sod2 prevent the hypoxia-mediated decrease in NA,K-atpase and alveolar fluid reabsorption

Article

Full-text available

Apr 2006

Renoprotection with Anti-Hypertensives: Reduction of Proteinuria and Improvement of Oxygenation via Inhibition of the Renin-Angiotensin System

Article

Full-text available

Jan 2005

Hypertension is a common cause of chronic kidney disease (CKD) and even more common sequelae of CKD. While strict control of blood pressure is essential to preserve residual renal function, numerous clinical trials have demonstrated that inhibitors of the renin-angiotensin system (RAS), i.e. angiontensin converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB), reduce the progression of CKD. These studies have examined type I and type II diabetic as well as non-diabetic nephropathies, utilizing end points such as serum creatinine, glomerular filtration rate, time to end-stage renal disease (ESRD), and death. These observations suggest that drugs blocking the RAS offer advantages beyond lowering blood pressure in diabetic and non-diabetic CKD. Therefore, guidelines recommend anti-hypertensives that block RAS in patients with CKD. Previous studies emphasized amelioration of glomerulosclerosis induced by glomerular hypertension as a renoprotective mechanism of inhibition of RAS. It should also be noted that progression to ESRD is mediated by two final common pathways; tubulointerstitial injury induced by proteinuria, and chronic hypoxia in the tubulointerstitium. Recent research indicates that reduction of proteinuria and improvement of oxygenation of the kidney are crucial mechanisms by which inhibition of RAS mediates renoprotection providing additional rationale for the use of ACEi and ARB to protect the kidney.

Nitric oxide contributes to right coronary vasodilation during systemic hypoxia

Article

Full-text available

Mar 2005

As arterial partial pressure of O(2) (Pa(O(2))) is reduced during systemic hypoxia, right ventricular (RV) work and myocardial O(2) consumption (MVo(2)) increase. Mechanisms responsible for maintaining RV O(2) demand/supply balance during hypoxia have not been delineated. To address this problem, right coronary (RC) blood flow and RV O(2) extraction were measured in nine conscious, instrumented dogs exposed to normobaric hypoxia. Catheters were implanted in the right ventricle for measuring pressure, in the ascending aorta for measuring arterial pressure and for sampling arterial blood, and in an RC vein. A flow transducer was placed around the RC artery. After recovery from surgery, dogs were exposed to hypoxia in a chamber ventilated with N(2), and blood samples and hemodynamic data were collected as chamber O(2) was reduced progressively to approximately 8%. After control measurements were made, the chamber was opened and the dog was allowed to recover. N(omega)-nitro-L-arginine (L-NNA) was then administered (35 mg/kg, via RV catheter) to inhibit nitric oxide (NO) production, and the hypoxia protocol was repeated. RC blood flow increased during hypoxia due to coronary vasodilation, because RC conductance increased from 0.65 +/- 0.05 to 1.32 +/- 0.12 ml x min(-1) x 100 g(-1) x L-NNA blunted the hypoxia-induced increase in RC conductance. RV O(2) extraction remained constant at 64 +/- 4% as Pa(O(2)) was decreased, but after L-NNA, extraction increased to 70 +/- 3% during normoxia and then to 78 +/- 3% during hypoxia. RV MVo(2) increased during hypoxia, but after L-NNA, MVo(2) was lower at any respective Pa(O(2)). The relationship between heart rate times RV systolic pressure (rate-pressure product) and RV MVo(2) was not altered by l-NNA. To account for L-NNA-mediated decreases in RV MVo(2), O(2) demand/supply variables were plotted as functions of MVo(2). Slope of the conductance-MVo(2) relationship was depressed by L-NNA (P = 0.03), whereas the slope of the extraction-MVo(2) relationship increased (P = 0.003). In summary, increases in RV MVo(2) during hypoxia are met normally by increasing RC blood flow. When NO synthesis is blocked, the large RV O(2) extraction reserve is mobilized to maintain RV O(2) demand/supply balance. We conclude that NO contributes to RC vasodilation during systemic hypoxia.

Peritubular Capillary Injury during the Progression of Experimental Glomerulonephritis in Rats

Article

Full-text available

Jan 2000

The functional and morphologic changes occurring in the peritubular capillaries (PTC) of the kidney during the progression of renal disease are not yet completely understood. In this study, the features of PTC disruption observed in a rat anti-glomerular basement membrane-induced glomerulonephritis (GN) model were characterized. Contributions to the progression of the disease made by other interstitial components, including ED-1-positive macrophages and CD3-positive T cells, were also investigated. Within 7 d of inducing GN, severe necrotizing glomerular injuries were observed. Thrombomodulin staining revealed that within 3 to 8 wk, there was a significant (P < 0.001) decline in the number of PTC, accompanied by a marked accumulation of macrophages, T cells, and fibrotic material. By the end of this period, most PTC were severely damaged or lost, and tubulointerstitial scarring was noted in the affected areas. Furthermore, PTC endothelial cell apoptosis occurred concomitantly, as shown by application of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling methods and electron microscopy. It was presumed that the PTC injury was mediated possibly by the infiltrating macrophages and T cells, which, together with destruction of the PTC structure, correlated significantly with the impairment of renal function. These findings suggest that PTC disruption and the subsequent regression of the capillary network may contribute to the development of the tubulointerstitial injury largely responsible for the renal dysfunction in progressive GN.

The severity of obstructive sleep apnoea is associated with insulin resistance

Article

Full-text available

Mar 1993
J SLEEP RES

SUMMARY Oral glucose tolerance tests (OGTT) were performed on eighteen patients with suspected obstructive sleep apnoea who also completed a whole-night polygraphic recording with oximetry. Insulin resistance indices (IRI) were calculated as the product of areas under glucose and insulin curves. In the resulting multiple regression analysis the dependent variable was IRI and the independent variables were age, body mass index (BMI) and the number of nocturnal hypoxic episodes with over 4% desaturation per hour (ODI4). ODI4 was between 4.6 and 70 (median 22.3); IRI ranged from 2.20 to 33.55 (median 7.50). In the regression model the coefficient of determination (R2) for IRI was 0.441 (F-ratio = 3.681, P= 0.038). The strongest determinant of IRI was ODI4 and the regression coefficient of BMI was not significantly different from zero even when possible outliers were excluded. It was found that insulin resistance is related to the severity of sleep anoea. This may be due to a hypoxia-induced hormonal stress reaction which decreases tissue insulin sensitivity. Since upper body obesity is associated with both insulin resistance and sleep apnoea, the distribution of fat should be taken into account in future studies.

The nutritional demands of very prolonged exercise in man

Article

Full-text available

Feb 1998

Michael A Stroud

Right and left ventricular dysfunction with severe pulmonary disease

Article

Full-text available

Mar 1998

To determine the prevalence of right and left ventricular dysfunction in a prescreened population of patients with severe pulmonary disease, and to analyze the relationship between right and left ventricular function. Retrospective record review of 434 patients with severe pulmonary disease. Patients with end-stage pulmonary disease, including alpha1-antitrypsin deficiency emphysema, COPD, cystic fibrosis (CF), idiopathic pulmonary fibrosis, and pulmonary hypertension (primary and Eisenmenger's syndrome), who were evaluated for lung transplantation between January 1993 and December 1995. Pulmonary function tests, arterial blood gases, radionuclide ventriculography, two-dimensional transthoracic echocardiography, pulmonary hemodynamics, coronary angiography. Right ventricular dysfunction (right ventricular ejection fraction [RVEF] <45%) was present in 267 patients (66%), but the prevalence was highest (94%) in patients with pulmonary vascular disease. Among the patients with airway or parenchymal lung disease, the prevalence ranged from 59% in COPD to 66% in CF. In contrast, left ventricular dysfunction (left ventricular ejection fraction [LVEF] <45%) was present in only 6.4%, but it, too, was most common in the group with pulmonary hypertension (19.6%). In the groups with parenchymal or airway disease, the prevalence was 3.6%, and there was no statistical difference among the four diagnoses (alpha1-antitrypsin deficiency emphysema; COPD; CF; idiopathic pulmonary fibrosis). LVEF showed a significant correlation with RVEF (r=0.44; p<0.05), and left ventricular dysfunction was associated with the presence of moderate-to-severe tricuspid regurgitation but not with coronary artery disease. In a subset of patients with both right and left ventricular dysfunction who subsequently underwent lung transplantation, RVEF and LVEF increased pari passu after transplantation. The prevalence of right ventricular dysfunction is high in patients with end-stage pulmonary disease, but the prevalence of left ventricular dysfunction is relatively low. Left ventricular dysfunction appears to be related to right ventricular dysfunction, perhaps through ventricular interdependence.

In vivo phosphorylation of the epithelial sodium channel

Article

Full-text available

Mar 1998

The activity of the epithelial sodium channel (ENaC) in the distal nephron is regulated by an antidiuretic hormone, aldosterone, and insulin, but the molecular mechanisms that mediate these hormonal effects are mostly unknown. We have investigated whether aldosterone, insulin, or activation of protein kinases has an effect on the phosphorylation of the channel. Experiments were performed in an epithelial cell line generated by stable cotransfection of the three subunits (alpha, beta, and gamma) of ENaC. We found that beta and gamma, but not the alpha subunit, are phosphorylated in the basal state. Aldosterone, insulin, and protein kinases A and C increased phosphorylation of the beta and gamma subunits in their carboxyl termini, but none of these agents induced de novo phosphorylation of alpha subunits. Serines and threonines but not tyrosines were found to be phosphorylated. The results suggest that aldosterone, insulin, and protein kinases A and C modulate the activity of ENaC by phosphorylation of the carboxyl termini of the beta and gamma subunits.

Correction for Fraser et al., Hypoxia-inducible myoglobin expression in nonmuscle tissues

Article

Full-text available

Jun 2006

Development of Lung Edema: Interstitial Fluid Dynamics and Molecular Structure

Article

Apr 2001
News Physiol Sci

Pulmonary interstitium is maintained dehydrated at subatmospheric pressure (-10 cmH(2)O) through low capillary permeability, low tissue compliance, and an efficient lymphatic drainage. Enzymatic degradation of proteoglycans disrupts the endothelial basal membrane and the matrix structure, triggering the development of pulmonary edema.

Skeletal muscle HIF-1alpha expression is dependent on muscle fiber type.

Article

Aug 2005

Inflammation, stress, and diabetes

Article

May 2005

Kathryn E Wellen

Endurance Running and the Evolution of Homo

Article

Dec 2004

Striding bipedalism is a key derived behaviour of hominids that possibly originated soon after the divergence of the chimpanzee and human lineages. Although bipedal gaits include walking and running, running is generally considered to have played no major role in human evolution because humans, like apes, are poor sprinters compared to most quadrupeds. Here we assess how well humans perform at sustained long-distance running, and review the physiological and anatomical bases of endurance running capabilities in humans and other mammals. Judged by several criteria, humans perform remarkably well at endurance running, thanks to a diverse array of features, many of which leave traces in the skeleton. The fossil evidence of these features suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years ago, and may have been instrumental in the evolution of the human body form.

Impaired Spatial Learning and Hyperactivity in Developing Rats Exposed to Intermittent Hypoxia

Article

Sep 2002

Barry W Row

Obstructive sleep apnea (OSA) is a frequent medical condition and is associated with cognitive impairments in adults and with hyperactivity and decreased school performance in children. In an adult rodent model, intermittent hypoxia (IH), such as occurs in OSA, is associated with neurodegenerative changes in the hippocampus and cortex and with spatial learning deficits. Because a unique developmental window of neural vulnerability to IH is present, we hypothesized that exposure to IH throughout the vulnerable ages would result in increased behavioral impairments in the juvenile rat. Rat pups were therefore exposed to either room air or IH beginning at postnatal (PN) d 10 until PN d 30. Learning and memory were assessed via a standard place-training version of the Morris water maze beginning at PN d 25. Locomotor activity was assessed on PN d 29 and 30. Pups exposed to IH displayed significant spatial learning impairments, and exposed male rats but not female rats displayed increased locomotor activity in the open field. Collectively, these findings indicate that exposure to IH at an age that corresponds to the peak incidence of OSA in children induces substantial learning impairment and gender-dependent behavioral hyperactivity in the juvenile rat. We postulate that this novel experimental model may allow for future exploration of mechanisms underlying the neurobehavioral deficits of children with OSA.

Title: Effects of CPAP on Cerebral Vascular Response to Hypoxia in Obstructive Sleep Apnea Patients

Article

Egr-1, a master switch coordinating upregulation of divergent gene families underlying ischemic stress

Article

Dec 2000

Activation of the zinc-finger transcription factor early growth response (Egr)-1, initially linked to developmental processes, is shown here to function as a master switch activated by ischemia to trigger expression of pivotal regulators of inflammation, coagulation and vascular hyperpermeability. Chemokine, adhesion receptor, procoagulant and permeability-related genes are coordinately upregulated by rapid ischemia-mediated activation of Egr-1. Deletion of the gene encoding Egr-1 strikingly diminished expression of these mediators of vascular injury in a murine model of lung ischemia/reperfusion, and enhanced animal survival and organ function. Rapid activation of Egr-1 in response to oxygen deprivation primes the vasculature for dysfunction manifest during reperfusion. These studies define a central and unifying role for Egr-1 activation in the pathogenesis of ischemic tissue damage.

Muscular Exercise, Lactic Acid, and the Supply and Utilisation of Oxygen

Article

Jan 1924

Molekulare Mechanismen der muskulären Anpassung

Article

Jul 2003

Martin Flück

Der Skelettmuskel besitzt eine ausgeprägte Fähigkeit, sich strukturell wie auch funktionell an verschiedene Stimuli anzupassen. Der Einsatz molekularbiologischer Technologie hat Aufschluss darüber gegeben, dass Trainingsreize im menschlichen Skelettmuskel rasch eine Steigerung der Transkription von Desoxyribonukleinsäuresequenzen (DNS) von metabolischen und regulatorischen Genen auf Botenribonukleinsäuren (mRNS) bewirken. Durch wiederholte, systematische Trainingsreize wird zudem die Konzentration einiger mitochondrialer und kontraktiler mRNS verändert. Diese bestimmten Veränderungen der Genexpression reflektieren die spezifischen Anpassungen der mitochondrialen und myofibrillären Struktur der Skelettmuskulatur an unterschiedliche Reize wie Ausdauer- und Krafttraining oder Immobilisierung. Mehrere molekulare Sensoren sind identifiziert, welche an der Übermittlung und der Integration von mechanischen, metabolen, hormonellen und neuralen Signalen der komplexeren Trainingsstimuli in die beobachtete Adaptation der Genexpression beteiligt sind. Die aktuelle Datenlage unterstützt das fundamentale Konzept, dass Genexpressionsänderungen über die Instruktion zur Synthese der kodierten Proteine für die Mikroadaptationen des trainierten Skelettmuskels in Richtung eines neuen Gleichgewichtszustandes verantwortlich sind.

OBSERVATIONS ON THE APPARENT ADAPTABILITY OF THE BODY TO INFECTIONS, UNUSUAL HARDSHIPS, CHANGING ENVIRONMENT AND PROLONGED STRENUOUS EXERTION

Article

Jan 1929

HORMONAL REGULATION OF PULMONARY EPITHELIAL SODIUM CHANNEL GENES IN HUMAN FETAL LUNG ??? 403

Article

Apr 1996

Vugranam C. Venkatesh

Triggering of Acute Myocardial Infarction by Heavy Physical Exertion -- Protection against Triggering by Regular Exertion

Article

Dec 1993

Despite anecdotal evidence suggesting that heavy physical exertion can trigger the onset of acute myocardial infarction, there have been no controlled studies of the risk of myocardial infarction during and after heavy exertion, the length of time between heavy exertion and the onset of symptoms (induction time), and whether the risk can be modified by regular physical exertion. To address these questions, we collected data from patients with confirmed myocardial infarction on their activities one hour before the onset of myocardial infarction and during control periods. Interviews with 1228 patients conducted an average of four days after myocardial infarction provided data on their usual annual frequency of physical activity and the time, type, and intensity of physical exertion in the 26 hours before the onset of myocardial infarction. We compared the observed frequency of heavy exertion (6 or more metabolic equivalents) with the expected values using two types of self-matched analyses based on a new case-crossover study design. The low frequency of heavy exertion during the control periods was validated by data from a population-based control group of 218 subjects. Of the patients, 4.4 percent reported heavy exertion within one hour before the onset of myocardial infarction. The estimated relative risk of myocardial infarction in the hour after heavy physical exertion, as compared with less strenuous physical exertion or none, was 5.9 (95 percent confidence interval, 4.6 to 7.7), Among people who usually exercised less than one, one to two, three to four, or five or more times per week, the respective relative risks were 107 (95 percent confidence interval, 67 to 171), 19.4 (9.9 to 38.1), 8.6 (3.6 to 20.5), and 2.4 (1.5 to 3.7). Thus, increasing levels of habitual physical activity were associated with progressively lower relative risks. The induction time from heavy exertion to the onset of myocardial infarction was less than one hour, and symptoms usually began during the activity. Heavy physical exertion can trigger the onset of acute myocardial infarction, particularly in people who are habitually sedentary. Improved understanding of the mechanisms by which heavy physical exertion triggers the onset of myocardial infarction and the manner in which regular exertion protects against it would facilitate the design of new preventive approaches.

Experiments on Muscle Haemoglobin in vivo; The Instantaneous Measurement of Muscle Metabolism

Article

Jan 1937

G. A. Millikan

Regulation of coronary flow

Article

Jan 1964

Robert M. Berne

Endothelial cell regulation of nitric oxide reduction during hypoxia in coronary microvessels and epicardial arteries

Article

Mar 2000
J CELL PHYSIOL

Nitric oxide (NO) synthesized by endothelial cell nitric oxide synthase (eNOS) elicits vasodilation of resistance-sized coronary microvessels. Since coronary blood flow increases during hypoxia, we tested the hypotheses that: (1) hypoxia results in increased blood flow through increased NO production mediated by the upregulation of both eNOS mRNA and protein and (2) the regulation of NO production in response to hypoxia differs in microvascular endothelial cells and nonresistance, epicardial endothelial cells. Monocultures of vascular endothelium from resistance (∼100 μ) and nonresistance epicardial arteries were established and characterized. Nitric oxide was quantitated using a chemiluminescence method. Hypoxia (pO2 = 10 mmHg) significantly increased NO production in both cell lines, with less NO produced in microvascular endothelium. Western blots demonstrated that hypoxia caused a time-dependent increase in eNOS protein in both lines, with an average 2.5-fold increase in nonresistance, epicardial endothelial cells compared to an average 1.7-fold increase in protein from microvascular endothelium. Total mRNA recovery increased 2.4 ± 0.6-fold within 30 min of hypoxia in nonresistance, epicardial endothelial cells with no increase in microvascular endothelial cells. Although hypoxia increased NO production in both populations of endothelial cells, the increase in NO production and eNOS protein in microvascular endothelium was less compared to nonresistance, epicardial endothelial cells. Furthermore, there was no significant upregulation of total mRNA for eNOS in microvascular endothelium. The data indicate that increased NO production in microvascular endothelium during hypoxia may be through translational or posttranslational modifications of the enzyme, whereas transcriptional upregulation may account for the increased NO production in nonresistance, epicardial endothelial cells. Oxygen-sensitive response mechanisms that modulate NO production may be different in endothelium from different coronary artery vascular beds. J. Cell. Physiol. 182:359–365, 2000. © 2000 Wiley-Liss, Inc.

The AGE‐receptor in the pathogenesis of diabetic complications

Article

Nov 2001
DIABETES-METAB RES

Helen Vlassara

Native glucose-derived glycation derivatives (advanced glycation end products, AGE) in vascular, renal and neuronal tissues contribute to organ damage. Glycation derivatives include a number of chemically and cell-reactive substances, also termed glycoxidation products or glycotoxins (GT). Cell-associated AGE-specific receptors (AGE-Rs), AGE-R1-3, RAGE, as well as the scavenger receptors ScR-II and CD-36 that are present on vascular, renal, hemopoietic, and neuronal/glial cells, serve in the regulation of AGE uptake and removal. AGE-Rs also modulate cell activation, growth-related mediators, and cell proliferation, consequently influencing organ structure/function. This occurs via oxidant stress triggered via receptor-dependent or -independent pathways, and leads to signal activation pathways, resulting in pro-inflammatory responses. In susceptible individuals, the AGE-R expression/function may be subject to environmental or gene-related modulation, which in turn may influence tissue-specific gene functions. In this context, altered expression and activity of AGE-R components has recently been found in both mouse diabetes models and humans with diabetic complications. Although several gene polymorphisms are detected in most AGE-R components, no significant correlation to diabetic complications has as yet been found. Further investigation is underway to define whether primary or secondary genetic links of pathogenic significance exist in this system. Various AGE-binding peptides or soluble receptors have emerged as potential sequestering agents for toxic AGEs as potential therapies for diabetic complications. Copyright © 2001 John Wiley & Sons, Ltd.

Markers of inflammation and myofibrillar proteins following eccentric exercise in humans

Article

Mar 2001

The purpose of this study was to examine the time-course and relationships of technetium-99m (99mTc) neutrophils in muscle, interleukin-6 (IL-6), myosin heavy chain fragments (MHC), eccentric torque, and delayed onset muscle soreness (DOMS) following eccentric exercise in humans. Twelve male subjects completed a pre-test DOMS questionnaire, performed a strength test and had 100 ml blood withdrawn for analysis of plasma IL-6 and MHC content. The neutrophils were separated, labelled with 99mTc, and re-infused into the subjects immediately before the exercise. Following 300 eccentric repetitions of the right quadriceps muscles on an isokinetic dynamometer, the subjects had 10 ml of blood withdrawn and repeated the eccentric torque exercise tests and DOMS questionnaire at 0, 2, 4, 6, 20, 24, 48, 72 h, and 6 and 9 days. Bilateral images of the quadriceps muscles were taken at 2, 4, and 6 h. Computer analysis of regions of interest was used to determine the average count per pixel. The 99mTc neutrophils and IL-6 increased up to 6 h post-exercise (P < 0.05). The neutrophils were greater in the exercised muscle than the non-exercised muscle (P < 0.01). The DOMS was increased from 0 to 48 h, eccentric torque decreased from 2 to 24 h, and MHC peaked at 72 h post-exercise (P < 0.001). Significant relationships were found between IL-6 at 2 h and DOMS at 24 h post-exercise (r=0.68) and assessment of the magnitude of change between IL-6 and MHC (r=0.66). These findings suggest a relationship between damage to the contractile proteins and inflammation, and that DOMS is associated with inflammation but not with muscle damage.

Ontogeny of locomotory behaviour in the American locust, Schistocerca americana: From marathoner to broad jumper

Article

Apr 2006

Developmental changes in locomotory ability may affect many aspects of organismal behaviour and ecological success. While juvenile vertebrates have lower power output and endurance than older animals, the effects of ontogeny on locomotory performance in invertebrates are unknown. Among insects, grasshoppers serve as an ideal model to study ontogeny of locomotory behaviour. Ecological and behavioural studies show that adult and juvenile grasshoppers have different predators and dispersal behaviours, suggesting different locomotory abilities. In addition, older American locust grasshoppers, Schistocerca americana, have improved oxygen delivery, which may enhance endurance. In this study, we forced American locust grasshoppers of different ages to jump repeatedly to exhaustion and quantified jump frequencies and distances. We found that, in contrast to vertebrates, grasshoppers appear to develop from low-power, high-endurance juveniles to high-power, low-endurance adults. These developmental changes in physiology match the ontogeny of life-history behaviours. Adult grasshopper jumping legs produce the high power output required to initiate flight for escape from vertebrate predators and migration, whereas high-endurance juvenile grasshoppers repeatedly jump to escape invertebrate predators and may also be forced to disperse long distances to find food.

Environmental enrichment results in higher levels of nerve growth mRNA in rat visual cortex and hippocampus

Article

Jul 1998
BEHAV BRAIN RES

Evidence for structural modifications in the brain following environmental changes have been provided during the last decades. The most pronounced alterations following environmental manipulations have been found in the visual cortex. These plastic changes are supposed to reflect reorganization of neuronal connections involved in postnatal development and adult adjustments of connections involved in sensori-perceptual processing and learning. Potential candidates to mediate these changes are neurotrophins. Nerve growth factor (NGF) has been associated with cognitive functions and shown to improve the performance of aged rats in spatial learning and memory tasks. In the central nervous system, NGF is of importance for development and maintenance of cholinergic neurons and atrophy of cholinergic neurons is strongly correlated with learning and memory impairments. Exposure to enriched environmental conditions improves learning and problem-solving ability and results in plastic changes in the brain. This study examined the effect of environmental enrichment on expression of NGF mRNA in the rat visual cortex and hippocampus. Rats housed in groups in a stimulus-rich environment for 30 days had significantly higher levels of NGF mRNA than rats housed individually in single cages without stimulus-enrichment. We have recently presented results showing higher levels of neurotrophin-3 (NT-3) mRNA and improved spatial learning following environmental enrichment, and suggest that an interplay involving the neurotrophins NGF and NT-3 may be mediating experience-induced structural changes.

Gender Differences in Dopaminergic Function in Striatum and Nucleus Accumbens

Article

Jan 2000
PHARMACOL BIOCHEM BE

Jill B. Becker

In female rats the gonadal hormones estrogen and progesterone modulate dopamine (DA) activity in the striatum and nucleus accumbens. For example, there is estrous cycle-dependent variation in basal extracellular concentration of striatal DA, in amphetamine (AMPH)-stimulated DA release, and in striatal DA-mediated behaviors. Ovariectomy attenuates basal extracellular DA, AMPH-induced striatal DA release, and behaviors mediated by the striatal DA system. Estrogen rapidly and directly acts on the striatum and accumbens, via a G-protein–coupled external membrane receptor, to enhance DA release and DA-mediated behaviors. In male rats, estrogen does not affect striatal DA release, and removal of testicular hormones is without effect. These effects of estrogen also result in gender differences in sensitization to psychomotor stimulants. The effects of the gonadal hormones on the striatum and ascending DA systems projecting to the striatum and nucleus accumbens are hypothesized to occur as follows: estrogen induces a rapid change in neuronal excitability by acting on membrane receptors located in intrinsic striatal GABAergic neurons and on DA terminals. The effect of these two actions results in enhanced stimulated DA release through modulation of terminal excitability. These effects of gonadal hormones are postulated to have important implications for gender differences in susceptibility to addiction to the psychomotor stimulants. It is suggested that hormonal modulation of the striatum may have evolved to facilitate reproductive success in female rats by enhancing pacing behavior.

Involvement of Microglial Receptor for Advanced Glycation Endproducts (RAGE) in Alzheimer's Disease: Identification of a Cellular Activation Mechanism

Article

Oct 2001

Receptor-mediated interactions with amyloid β-peptide (Aβ) could be important in the evolution of the inflammatory processes and cellular dysfunction that are prominent in Alzheimer's disease (AD) pathology. One candidate receptor is the receptor for advanced glycation endproducts (RAGE), which can bind Aβ and transduce signals leading to cellular activation. Data are presented showing a potential mechanism for Aβ activation of microglia that could be mediated by RAGE and macrophage colony-stimulating factor (M-CSF). Using brain tissue from AD and nondemented (ND) individuals, RAGE expression was shown to be present on microglia and neurons of the hippocampus, entorhinal cortex, and superior frontal gyrus. The presence of increased numbers of RAGE-immunoreactive microglia in AD led us to further analyze RAGE-related properties of these cells cultured from AD and ND brains. Direct addition of Aβ(1–42) to the microglia increased their expression of M-CSF. This effect was significantly greater in microglia derived from AD brains compared to those from ND brains. Increased M-CSF secretion was also demonstrated using a cell culture model of plaques whereby microglia were cultured in wells containing focal deposits of immobilized Aβ(1–42). In each case, the Aβ stimulation of M-CSF secretion was significantly blocked by treatment of cultures with anti-RAGE F(ab′)2. Treatment of microglia with anti-RAGE F(ab′)2 also inhibited the chemotactic response of microglia toward Aβ(1–42). Finally, incubation of microglia with M-CSF and Aβ increased expression of RAGE mRNA. These microglia also expressed M-CSF receptor mRNA. These data suggest a positive feedback loop in which Aβ–RAGE-mediated microglial activation enhances expression of M-CSF and RAGE, possibly initiating an ascending spiral of cellular activation.

Soluble cytochrome b5 reductase from human erythrocytes

Article

Jul 1972
BBA-BIOENERGETICS

1. An enzyme that catalyzes the reduction of erythrocyte cytochrome b5 has been isolated from the supernatant fraction of erythrocyte hemolysates by chromatography on DEAE-cellulose, Amberlite CG-50, and Bio-Gel P-60.2. Erythrocyte cytochrome b5 reductase has been shown to contain FAD. Incubation of the reductase in the absence of EDTA results in both the appearance of flavin fluorescence and the loss of enzymatic activity with time.3. The reductase catalyzes the reduction of erythrocyte cytochrome b5 50 times faster with NADH than with NADPH. The apparent Km of NADH was calculated to be 1.6×10−6M and the turnover number is 1280 moles of cytochrome b5 per min per mole of flavin. The reduction of electron acceptors proceeded in the following decreasing order of rate: K3Fe(CN)6, 2,6-dichlorophenolindophenol (DCIP), cytochrome b5, methylene blue, cytochrome c, O2, oxidized glutathione, and methemoglobin.4. The FAD prosthetic group, the substrate specificity, and the effect of ionic strength, pH, and EDTA on activity suggest that the reductase is the same enzyme as NADH dehydrogenase I, the enzyme lacking in many cases of congenital methemoglobinemia. The properties of the reductase, including its molecular weight, are very similar to those of the cytochrome b5 reductases solubilized from microsomes and mitochondria of other tissues.

Pulmonary interstitial pressure in preterm rabbits

Article

Jan 1996
Respir Physiol

By micropuncture technique we measured pulmonary interstitial pressuure (Pip) from birth up to 6 h postnatal age in anesthetized and paralyzed cesarian delivered term (31 days gestation) and premature (27 to 30 days gestation) rabbits. In term cesarian delivered rabbits Pip followed the time course of vaginally delivered rabbits, namely, it increased from about zero at birth up to about 5 cmH2O at 2 h, as a result of alveolar fluid reabsorption, subsequently it decreased becoming subatmospheric due to progressive interstitial fluid drainage. In ventilated lung regions of premature rabbits, Pip also peaked to about 5 cmH2O at 2 h but its subsequent decrease was markedly slowed down while in atelectatic regions of premature rabbits Pip remained slightly subatmospheric. Up to 6 h, the wet/dry weight ratio of the lung was higher in premature relative to vaginally and cesarian delivered term rabbits (at birth 8.4 ± 0.9 vs. 7.5 ± 0.8). In 29–31 days rabbits, plasma protein concentration at birth was 3.6 ± 0.5 g/dl (within 95% confidence limits for vaginally delivered rabbits, considered as control) while in 27–28 days rabbit it was 3.1 ± 0.4 g/dl (at the lower edge of control confidence limits). In the first postnatal hours, the increase in Pip favoured fluid reabsorption into pulmonary microcirculation in term cesarian delivered rabbits and in ventilated regions of premature rabbits. Conversely, in the atelectatic regions of premature rabbits the unchanged Pip value in the postnatal hours favours fluid filtration from microcirculation into lung interstitium.

Effects of Chronic Hypoxia, Normoxia and Hyperoxia on Larval Development in the Beetle Tenebrio molitor

Article

Nov 1996
J INSECT PHYSIOL

The effect of chronic hypoxia and hyperoxia on survival, developmental time, body mass, growth and moulting in Tenebrio molitor larvae were studied. Larvae were reared from eggs to pupae at 25 °C, 70% relative humidity, in 3 different oxygen environments: normoxia (21%), hypoxia (10%) and hyperoxia (40%) balanced by nitrogen (at sea level). 20% of larvae in hypoxia, and 96% in normoxia and hyperoxia survived to pupation. It was estimated that hypoxic, normoxic and hyperoxic larvae moulted 12.3, 5.8 and 3.9 times, respectively, between day 38 and the beginning of pupation. Body mass growth patterns were fitted to 3rd degree polynomial equations. The lowest growth rate was found in the hypoxic group. No differences in growth rate during the steep mass increase phase were found between the hyperoxic and the normoxic larvae. Despite a low total number of moults in hyperoxia, larvae finally reached a body mass similar to those reared in normoxia. This suggests that oxygen availability affects moulting. Our results indicate that the trigger for moulting is related to the atmospheric oxygen availability and to the size of the tracheal system, which must supply sufficient oxygen to meet tissue demands.

Direct oxygen measurements in the tracheal system of Lepidopterous pupae using miniaturized amperometric sensors

Article

May 1994
Bioelectrochem Bioenerg

Changes in the oxygen content in the tracheal system of moth pupae during discontinuous carbon dioxide release were recorded using small pO2 sensors. The sensors were designed as miniaturized Clark electrodes with relatively high mechanical stability and a very low oxygen consumption of only 1–2 pmol min-1. The results obtained with these electrodes are in accordance with data presented in the literature. The measuring technique allows easy determination of oxygen consumption even at respiration rates below 2 nmol O2 g-1 min-1 and is thus recommended in investigations of insect respiration at low metabolism.

Hippocampal area metabolites relate to severity and cognitive function in obstructive sleep apnea

Article

Nov 2004
SLEEP MED

Obstructive sleep apnea (OSA) is associated with intermittent hypoxia and cognitive decrements. As the hippocampus is particularly susceptible to hypoxia, we hypothesized that it may show biochemical abnormalities, and they may relate to apnea severity. Eight males with OSA and five age-matched controls underwent neurocognitive testing before and after polysomnography and proton magnetic resonance spectra were obtained from the left hippocampal area of all subjects. In the left hippocampal area, N-acetyl-containing/creatine-containing compounds was significantly increased in OSA (P=0.04). Inspection of these compounds with respect to the water resonance indicated that this was most likely due to a decrease in creatine-containing compounds rather than any change in N-acetyl-containing compounds. Lower levels of hippocampal creatine-containing compounds were correlated with worse OSA severity and neurocognitive performance. We suggest the changes in creatine levels in the hippocampal area represent adjustments to brain bioenergetics, similar to those seen in ischemic preconditioning, and may reflect the different susceptibility of these tissues to hypoxic damage in OSA.

Plasma insulin and lipid levels in untreated obstructive sleep apnoea and snoring; their comparison with matched controls and response to treatment

Article

Sep 1994

Obstructive sleep apnoea (OSA), and snoring are associated with coronary heart disease. To assess whether OSA or snoring may contribute to this by raising fasting lipid or insulin levels, venous fasting total cholesterol, triglyceride, very‐low‐density lipoprotein, low‐density lipoprotein, high‐density lipoprotein, and insulin were measured in 15 untreated OSA patients and 18 snorers. Each of these subjects was individually matched to a control of the same sex, age ± 10%, body index ± 15%, smoking and drinking habits. This produced study groups which did not differ significantly by any of these criteria. Fasting venous blood samples were collected at 06.30 hours following polysomnography, and analysed blind of the subjects respiratory status. The OSA patients were then treated with nasal continuous positive airway pressure. In 10 of these subjects lipid and insulin levels were repeated after more than three months treatment. Lipid and insulin levels were also remeasured in the controls matched to these 10 subjects. The end points were compared with paired t ‐tests. There was no difference in any of the end points when the untreated OSA patients and the snorers were compared to their matched controls ( P >0.25 for all comparisons), and none of the indices changed when OSA was corrected with nasal continuous positive airway pressure ( P > 0.25 for all comparisons). Patients with obstructive sleep apnoea or snoring do not have significant fasting hyperlipidaemia or hyperinsulinaemia when compared to carefully matched controls. These factors are therefore unlikely to be the cause of the excess cardiovascular mortality experienced by this patient group.

Contribution of Tonic Chemoreflex Activation to Sympathetic Activity and Blood Pressure in Patients With Obstructive Sleep Apnea

Article

Mar 1998

Muscle sympathetic nerve activity (MSNA) is increased in patients with obstructive sleep apnea (OSA). We tested the hypothesis that tonic activation of excitatory chemoreceptor afferents contributes to the elevated sympathetic activity in OSA. Using a double-blind, randomized, vehicle-controlled design, we examined the effects of chemoreflex deactivation (by comparing effects of breathing 100% oxygen for 15 minutes with effects of breathing room air for 15 minutes) on MSNA, heart rate, blood pressure, and minute ventilation in 14 untreated patients with OSA and in 12 normal subjects matched for age and body mass index. All control subjects underwent overnight polysomnography to exclude the existence of occult OSA. Baseline MSNA was markedly elevated in the patients with OSA compared with the control subjects (44+/-4 versus 30+/-3 bursts per minute; P=.01). In both control subjects and patients with OSA, heart rate decreased during administration of 100% oxygen but did not change during administration of room air. By contrast, both MSNA (P=.008) and mean arterial pressure (P=.02) were significantly reduced during chemoreflex deactivation by 100% oxygen only in patients with OSA but not in control subjects. Tonic activation of excitatory chemoreflex afferents may contribute to increased efferent sympathetic activity to muscle circulation in patients with OSA.

Angiotensin II Nitric Oxide Interaction on Sympathetic Outflow in Conscious Rabbits

Article

Mar 1998

Increasing evidence suggests that endogenous NO inhibits sympathetic outflow in anesthetized animals. However, in a recent study from this laboratory, we were unable to find any evidence of increased renal sympathetic nerve activity (RSNA) in response to blockade of NO synthesis in conscious rabbits. Because angiotensin II (Ang II) increases sympathetic outflow, one factor for this discrepancy may be the difference in the resting level of Ang II, which may be lower in well-trained conscious animals. In the present study, the effects of blockade of NO synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg IV) on resting RSNA with and without a background intravenous infusion of Ang II (10 ng.kg(-1).min(-1)) was investigated in conscious rabbits. Intravenous administration of L-NAME (30 mg/kg) caused an increase in mean arterial blood pressure (MAP, from 80.4+/-2.9 to 92.8+/-2.5; P=.0001) and a decrease in RSNA (from 100+/-0% to 53.4+/-8.6%, P=.0016). When the elevated blood pressure was returned to control by infusion of hydralazine (0.01 to 0.06 mg.kg(-1).min(-1)), RSNA returned to the level before L-NAME administration. During a sustained infusion of Ang II (10 ng.kg(-1).min(-1)), L-NAME increased MAP from 89.2+/-2.9 to 109.0+/-4.3 mm Hg (P=.0101) and decreased RSNA from 100.0+/-0% to 53.7+/-7.5% (P=.0013). Under this circumstance, however, when the MAP was returned to the level that existed before the administration of L-NAME, RSNA increased significantly above the level that existed before the administration of L-NAME (164.5+/-17.7% versus 100+/-0%, P=.0151). The enhancement of the sympathetic response by Ang II was completely blocked by the AT1 receptor antagonist, losartan. In contrast, during a background infusion of phenylephrine, which increased MAP to the same level as produced by Ang II, L-NAME had no effect on RSNA when MAP was returned to the control level. Nomega-Nitro-D-arginine methyl ester had no effect on MAP and RSNA. Intravenous infusion of Ang II alone for 75 minutes had no effect on RSNA when MAP was returned to control levels. These data suggest that an elevated level of Ang II is critical for the inhibitory effect of NO on sympathetic outflow in conscious rabbits and imply that these two substances have a major impact on the regulation of sympathetic outflow.

The Heart of the Antarctic

Article

Hypoxia in cartilage: HIF-1alpha is essential for chondrocyte growth arrest and survival

Article

Dec 2001
GENE DEV

Breakdown or absence of vascular oxygen delivery is a hallmark of many common human diseases, including cancer, myocardial infarction, and stroke. The chief mediator of hypoxic response in mammalian tissues is the transcription factor hypoxia-inducible factor 1 (HIF-1), and its oxygen-sensitive component HIF-1α. A key question surrounding HIF-1α and the hypoxic response is the role of this transcription factor in cells removed from a functional vascular bed; in this regard there is evidence indicating that it can act as either a survival factor or induce growth arrest and apoptosis. To study more closely how HIF-1α functions in hypoxia in vivo, we used tissue-specific targeting to delete HIF-1α in an avascular tissue: the cartilaginous growth plate of developing bone. We show here the first evidence that the developmental growth plate in mammals is hypoxic, and that this hypoxia occurs in its interior rather than at its periphery. As a result of this developmental hypoxia, cells that lack HIF-1α in the interior of the growth plate die. This is coupled to decreased expression of the CDK inhibitor p57, and increased levels of BrdU incorporation in HIF-1α null growth plates, indicating defects in HIF-1α-regulated growth arrest occurs in these animals. Furthermore, we find that VEGF expression in the growth plate is regulated through both HIF-1α-dependent and -independent mechanisms. In particular, we provide evidence that VEGF expression is up-regulated in a HIF-1α-independent manner in chondrocytes surrounding areas of cell death, and this in turn induces ectopic angiogenesis. Altogether, our findings have important implications for the role of hypoxic response and HIF-1α in development, and in cell survival in tissues challenged by interruption of vascular flow; they also illustrate the complexities of HIF-1α response in vivo, and they provide new insights into mechanisms of growth plate development.

Detection of mutant hemoglobins with altered affinity for oxygen. A simplified technique

Article

Jun 1976

The detection of high- or low-affinity hemoglobins in subjects with polycythemia or anemia is difficult for most physicians because of the requirement for special equipment to do oxygen-hemoglobin dissociation curves. Measurement of the pH, oxygen tension, and oxygen saturation of antecubital venous blood with instruments present in most clinical chemistry laboratories permits an estimate of the strength of oxygen binding to hemoglobin. An equation can be used to convert the venous oxygen tension (standardized to pH 7.4) and the oxygen saturation to the P50 of the oxygen-hemoglobin dissociation curve on which the observed point falls. The data indicate that this method is a reliable initial step in the identification of a hemoglobin with abnormal affinity for oxygen and may be applied to population studies, since reliable results are obtained with venous blood stored at 4 degrees C for up to 24 hours.

Capillary recruitment during airway hypoxia: Role of pulmonary artery pressure

Article

Sep 1979

Hypoxia has been shown to cause an increased number of pulmonary capillaries to be perfused. Changes in cardiac output and left atrial pressure have been previously ruled out as causes of this capillary recruitment. Increased pulmonary vein pressure and increased pulmonary artery pressure remain as two potential mechanisms. To differentiate between these two possible causes, we measured pulmonary artery and vein pressures with directly placed catheters and capillary recruitment with in vivo microscopy. During isocapnic hypoxia pulmonary artery pressure doubled, observed capillary recruitment increased fivefold, and pulmonary vein pressure remained constant. When the vasodilator prostaglandin E1 was infused during hypoxia, pulmonary artery pressure and capillary recruitment fell to control values and pulmonary vein pressure remained constant. Since capillary recruitment correlated with pulmonary artery pressure in each dog, but not with pulmonary vein pressure, we conclude that arterial, not venous, constriction is the probable cause of this recruitment.

Effect of the Exercise of Seven Consecutive Days Hill-Walking on Fluid Homeostasis

Article

May 1979

1. The effect of 7 consecutive days of strenuous exercise, hill-walking, on water balance and distribution was studied in five subjects. The exercise was preceded and followed by 3 control days. The diet was fixed throughout but water was allowed ad libitum. 2. Packed cell volume was measured daily. Serum electrolytes and arginine vasopressin were measured twice daily. Daily water, sodium and potassium balances were calculated. 3. During exercise there was a fall in packed cell volume, reaching a maximum of 11% by day 5 and a retention of sodium reaching a cumulative maximum of 358 mmol by day 6. During and immediately after exercise there was a retention of potassium, reaching a total of 120 mmol by day 3 after stopping exercise. 4. There was a loss of 650 ml of water on day 1 of exercise, followed by a modest retention reaching a cumulative maximum of 650 ml on day 5 of exercise. 5. Neither arginine vasopressin nor serum electrolyte concentrations were affected by exercise. 6. From the packed cell volume, sodium and water balances it was calculated that by day 5 of exercise there was an increase in plasma volume of 0·68 litre (22%), an increase in interstitial fluid volume of 2·0 litres (17%) and a decrease in intracellular fluid volume of 1·8 litres (8%). 7. These changes, together with the clinical observation of facial and ankle oedema during the experiment, suggest that continuous exercise may cause oedema and thus may be a factor in the aetiology of high-altitude oedema.

Differential permeability of endothelial and epithelial barriers to albumin

Article

Jan 1980

We measured the flux of albumin between the vascular space and the pulmonary interstitial and luminal lining fluids in 20 adult sheep with chronic lung lymph fistulas. We sampled the bronchoalveolar lining layer by episodic fiberbronchoscopic lavage. A total of 62 alveolar lavages were performed at times ranging between 30 min and 60 h after intra-arterial injection of 100 microCi of 125I-labeled albumin. Samples of lymph and plasma were obtained simultaneously with lavage fluid, and the radioactivity and albumin content of all samples were measured and expressed as specific activity (counts/min . g albumin). We found that alveolar lavage fluid collected by our technique is not significantly contaminated by plasma or interstitial fluid proteins. Proteins present in alveolar lavage fluid and also present in plasma reach the alveolar space by a normal diffusive process, and not as a result of epithelial membrane damage occurring at the time of lavage. Lung epithelial permeability to albumin in small, but finite (4.3--5.8 x 10(-10) cm/s). Virtually all (greater than 92%) of resistance to albumin flux across the alveolocapillary membrane lies in the epithelial barrier. Increases in permeability of the respiratory epithelium, even minor, would have a marked effect on water and solute balance in the lung. Epithelial injury will potentiate pulmonary edema formation even in the presence of normal pulmonary microvascular pressure, plasma oncotic pressure, and endothelial permeability.

Prostaglandin mediated relaxation of coronary artery strips under hypoxia

Article

Oct 1978
Prostag Med

Stanley Kalsner

Strips of beef coronary branch arteries, maintained in vitro, respond to decreased PO2 in the bathing medium with relaxations which are much attenuated by pretreatment with indomethacin or aspirin. It was determined that these hypoxia-induced relaxations are sustained until strips are returned to an environment of high PO2 and that the mechanism involved does not fatigue readily with repetitive exposure to hypoxic stress (53 mm Hg). It was also established that the reduced relaxations observed in the presence of inhibitors of prostaglandin synthesis were not enlarged with time by the development of an alternate process of relaxation independent of prostaglandins. Other experiments showed that when prostaglandin intervention is blocked with inhibitors the strips maintain a given level of tone to potassium chloride under a PO2 of 53 mm Hg, and do so without significant impairment over an observation period of one hour. Similarly, complete concentration-response curves to potassium did not differ under high (515 mm Hg) or low (53 mm Hg) PO2. This confirms that hypoxia-induced relaxation in beef coronary artery strips is a specific process, apparently mediated by a prostaglandin, rather than any consequence of the failure of the energetics of contraction.

Regulation and Role of Neuroglobin and Cytoglobin Under Hypoxia

Abstract

No full-text available

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