Lauren G Koch

University of Michigan, Ann Arbor, Michigan, United States

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Publications (128)455.82 Total impact

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    ABSTRACT: Rats with Metabolic Syndrome (MetaS) have a dysregulated immune response to the aseptic trauma of surgery. We hypothesized that rats with MetaS would have dysregulated inflammation, increased lung injury, and less effective antibacterial defenses during Staphylococcus (S.) aureus sepsis as compared to rats without MetaS. Low capacity runner (LCR; a model of MetaS) and high capacity runner (HCR) rats were challenged intravenously with S. aureus bacteria. After 48 h, inflammatory mediators and bacteria were quantified in the blood, bronchoalveolar lavage fluid (BALF), and lung homogenates. Lungs were analyzed histologically. BALF protein and lung wet-dry ratios were quantified to assess for vascular leak. Endpoints were compared in infected LCR vs HCR rats. LCR rats had higher blood and lung S. aureus counts, as well as higher levels of IL-6 in plasma, lungs and BALF, MIP-2 in plasma and lung, and IL-17A in lungs. Conversely, LCR rats had lower levels of IL-10 in plasma and lungs. Although lactate levels, and liver and renal function tests were similar between groups, LCR rats had higher BALF protein and lung wet-dry ratios, and more pronounced acute lung injury histologically. During S. aureus bacteremia, as compared with HCR rats, LCR (MetaS) rats have heightened pro-inflammatory responses, accompanied by increased acute lung injury and vascular leak. Notably, despite an augmented pro-inflammatory phenotype, LCR rats have higher bacterial levels in their blood and lungs. The MetaS state may exacerbate lung injury and vascular leak by attenuating the inflammation-resolving response, and by weakening antimicrobial defenses.
    PLoS ONE 05/2015; 10(5). DOI:10.1371/journal.pone.0126906. · 3.53 Impact Factor
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    ABSTRACT: We studied the rat model system of high- vs. low-capacity runner (HCR vs. LCR) rats to question the atherogenic properties (oxidative stress, triglycerides and cholesterol metabolism) in the rat macrophages, serum, liver and heart. Half of the LCR or HCR rats consumed pomegranate juice (PJ; 15 μmol of gallic acid equivalents/rat/day) for 3weeks and were compared to placebo-treated rats. At the end of the study blood samples, peritoneal macrophages (RPM), livers, and hearts were harvested from the rats. RPM harvested from HCR vs. LCR demonstrated reduced cellular oxidation (21%), increased paraoxonase 2 activity (28%) and decreased triglycerides mass (44%). Macrophage uptake rates of fluorescein-isothiocyanate-labeled low-density lipoprotein (LDL) or oxidized LDL were significantly lower, by 37% or by 18%, respectively, in HCR vs. LCR RPM. PJ consumption significantly decreased all the above atherogenic parameters with more substantial beneficial effects observed in the LCR vs. the HCR rats (~80% vs. ~40% improvement, respectively). Similar hypo-triglyceridemic pattern was noted in serum from HCR vs. LCR. In contrast to the above results, liver oxidation and triglycerides mass were both minimally increased in HCR vs. LCR rats by 31% and 28%, respectively. In the heart, lipid content was very low, and interestingly, an absence of any significant oxidative stress, along with modest triglyceride accumulation, was observed. We conclude that HCR vs. LCR rats demonstrate reduced atherogenicity, mostly in their macrophages. PJ exerts a further improvement, mostly in macrophages from LCR rats. Copyright © 2015. Published by Elsevier Inc.
    The Journal of nutritional biochemistry 05/2015; DOI:10.1016/j.jnutbio.2015.04.001 · 4.59 Impact Factor
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    Journal of the American College of Cardiology 04/2015; 65(13):1378-80. DOI:10.1016/j.jacc.2015.01.041 · 15.34 Impact Factor
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    ABSTRACT: Maximal exercise-associated oxidative capacity is strongly correlated with health and longevity in humans. Rats selectively bred for high running capacity (HCR) have improved metabolic health and are longer-lived than their low-capacity counterparts (LCR). Using metabolomic and proteomic profiling, we show that HCR efficiently oxidize fatty acids (FAs) and branched-chain amino acids (BCAAs), sparing glycogen and reducing accumulation of short- and medium-chain acylcarnitines. HCR mitochondria have reduced acetylation of mitochondrial proteins within oxidative pathways at rest, and there is rapid protein deacetylation with exercise, which is greater in HCR than LCR. Fluxomic analysis of valine degradation with exercise demonstrates a functional role of differential protein acetylation in HCR and LCR. Our data suggest that efficient FA and BCAA utilization contribute to high intrinsic exercise capacity and the health and longevity benefits associated with enhanced fitness. Copyright © 2015 Elsevier Inc. All rights reserved.
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    ABSTRACT: Divergent selection has created rat phenotypes of high- and low-capacity runners (HCR and LCR, respectively) that have differences in aerobic capacity and correlated traits such as adiposity. We analysed visceral adipose tissue of HCR and LCR using label-free HDMSE profiling. The running capacity of HCR was 9-fold greater than LCR. Proteome profiling encompassed 448 proteins and detected 30 significant (p <0.05; false discovery rate <10%, calculated using q-values) differences. Approximately half of the proteins analysed were of mitochondrial origin, but there were no significant differences in the abundance of proteins involved in aerobic metabolism. Instead, adipose tissue of LCR rats exhibited greater abundances of proteins associated with adipogenesis (e.g. cathepsin D), endoplasmic reticulum stress (e.g. 78 kDa glucose response protein) and inflammation (e.g. Ig gamma-2B chain C region). Whereas the abundance anti-oxidant enzymes such as superoxide dismutase [Cu-Zn] was greater in HCR tissue. Putative adipokines were also detected, in particular protein S100-B, was 431% more abundant in LCR adipose tissue. These findings reveal low running capacity is associated with a pathological profile in visceral adipose tissue proteome despite no detectable differences in mitochondrial protein abundance. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Proteomics 03/2015; DOI:10.1002/pmic.201400537 · 3.97 Impact Factor
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    ABSTRACT: Brain iron overload has a key role in brain injury after intracerebral hemorrhage (ICH). Our recent study demonstrated that ICH-induced brain injury was greater in low capacity runner (LCR) than in high capacity runner (HCR) rats. The present study examines whether iron-induced brain injury differs between LCRs and HCRs. Adult male LCR and HCR rats had an intracaudate injection of iron or saline. Rats were euthanized at 2 and at 24 h after T2 magnetic resonance imaging, and the brains were used for immunostaining and Western blotting. LCRs had more hemispheric swelling, T2 lesion volumes, blood-brain barrier disruption, and neuronal death at 24 h after iron injection (p < 0.05). Many propidium iodide (PI)-positive cells, indicative of necrotic cell death, were observed in the ipsilateral basal ganglia of both HCRs and LCRs at 2 h after iron injection. PI fluorescence intensity was higher in LCRs than in HCRs. In addition, membrane attack complex (MAC) expression was increased at 2 h after iron injection and was higher in LCRs than in HCRs. The PI-positive cells co-localized with MAC-positive cells in the ipsilateral basal ganglia. Iron induces more severe necrotic brain cell death, brain swelling, and blood-brain barrier disruption in LCR rats, which may be related with complement activation and MAC formation.
    Translational Stroke Research 02/2015; 6(3). DOI:10.1007/s12975-015-0388-8 · 1.94 Impact Factor
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    ABSTRACT: Ovariectomized (OVX) rodents model human menopause in that they rapidly gain weight, reduce spontaneous physical activity (SPA) and develop metabolic dysfunction including insulin resistance. How contrasting aerobic fitness levels impacts OVX-associated metabolic dysfunction is not known. Female rats selectively bred for high and low intrinsic aerobic fitness (HCR and LCR, respectively) were maintained under sedentary conditions for 39 weeks. Midway through the observation period, OVX or sham (SHM) operations were performed providing HCR-SHM, HCR-OVX, LCR-SHM, LCR-OVX groups. Glucose tolerance, energy expenditure and SPA were measured before and 4 weeks after surgery while body composition via DXA and adipose tissue distribution, brown adipose tissue (BAT) and skeletal muscle phenotype, hepatic lipid content, insulin resistance via HOMA-IR and AdipoIR, and blood lipids were assessed at sacrifice. Remarkably, HCR were protected from OVX-associated increases in adiposity and insulin resistance, observed only in LCR. HCR rats were ~30% smaller, had ~70% greater SPA, consumed ~10% more relative energy, had greater skeletal muscle PGC1-α and ~40% more BAT. OVX did not increase energy intake and reduced SPA to the same extent in both HCR and LCR. LCR were particularly affected by an OVX-associated reduction in resting energy expenditure and experienced a reduction in relative BAT; resting energy expenditure correlated positively with BAT across all animals (r = 0.6, P<0.001). In conclusion, despite reduced SPA following OVX, high intrinsic aerobic fitness protects against OVX-associated increases in adiposity and insulin resistance. The mechanism may involve preservation of resting energy expenditure. Copyright © 2014, American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.
    AJP Regulatory Integrative and Comparative Physiology 01/2015; 308(6):ajpregu.00401.2014. DOI:10.1152/ajpregu.00401.2014 · 3.53 Impact Factor
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    ABSTRACT: Prolonged mechanical ventilation (MV) leads to rapid diaphragmatic atrophy and contractile dysfunction, which is collectively termed "ventilator-induced diaphragm dysfunction" (VIDD). Interestingly, endurance-exercise training prior to MV has been shown to protect against VIDD. Further, recent evidence reveals that sedentary animals selectively bred to possess a high aerobic capacity possess a similar skeletal muscle phenotype to muscles from endurance trained animals. Therefore, we tested the hypothesis that animals with a high intrinsic aerobic capacity would naturally be afforded protection against VIDD. To this end, animals were selectively bred over 33 generations to create two divergent strains, differing in aerobic capacity; high capacity runners (HCR) and low capacity runners (LCR). Both groups of animals were subjected to 12 hours of MV and compared to non-ventilated control animals within the same strains. As expected, contrasted to LCR animals, the diaphragm muscle from the HCR animals contained higher levels of oxidative enzymes (e.g., citrate synthase) and antioxidant enzymes (e.g., superoxide dismutase and catalase). Nonetheless, compared to non-ventilated controls, prolonged MV resulted in significant diaphragmatic atrophy and impaired diaphragm contractile function in both the HCR and LCR animals and the magnitude of VIDD did not differ between strains. In conclusion, these data demonstrate that possession of a high intrinsic aerobic capacity alone does not afford protection against VIDD. Importantly, these results suggest that endurance-exercise training differentially alters the diaphragm phenotype to resist VIDD. Interestingly, levels of heat shock protein 72 did not differ between strains; thus, potentially representing an important area of difference between animals. Copyright © 2014, Journal of Applied Physiology.
    Journal of Applied Physiology 01/2015; 118(7):jap.00797.2014. DOI:10.1152/japplphysiol.00797.2014 · 3.43 Impact Factor
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    ABSTRACT: The oxidative stress effect of exercise training on testis function is under debate. In the present study we used a unique rat model system developed by artificial selection for low and high intrinsic running capacity (LCR and HCR, respectively) to evaluate the effects of exercise training on apoptosis and spermatogenesis in testis. Twenty-four 13-month-old male rats were assigned to four groups: control LCR (LCR-C), trained LCR (LCR-T), control HCR (HCR-C), and trained HCR (HCR-T). Ten key proteins connecting aerobic exercise capacity and general testes function were assessed, including those that are vital for mitochondrial biogenesis. The VO2 max of LCR-C group was about 30% lower than that of HCR-C rats, and the SIRT1 levels were also significantly lower than HCR-C. Twelve weeks of training significantly increased maximal oxygen consumption in LCR by nearly 40% whereas HCR remained unchanged. LCR-T had significantly higher levels of peroxisome proliferator-activated receptor-gamma coactivator-1 (PGC-1α), decreased levels of reactive oxygen species and increased acetylated p53 compared to LCR-C, while training produced no significant changes for these measures in HCR rats. BAX and Blc-2 were not different among all four groups. The levels of outer dense fibers -1 (Odf-1), a marker of spermatogenesis, increased in LCR-T rats, but decreased in HCR-TR rats. Moreover, exercise training increased the levels of lactate dehydrogenase C (LDHC) only in LCR rats. These data suggest that rats with low inborn exercise capacity can increase whole body oxygen consumption and running exercise capacity with endurance training and, in turn, increase spermatogenesis function via reduction in ROS and heightened activity of p53 in testes.
    PLoS ONE 12/2014; 9(12):e114075. DOI:10.1371/journal.pone.0114075 · 3.53 Impact Factor
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    ABSTRACT: Daily physical activity shows substantial inter-individual variation, and low physical activity is associated with obesity and weight gain. Elevated physical activity is also associated with high intrinsic aerobic capacity, which confers considerable metabolic health benefits. Rats artificially selected for high intrinsic aerobic capacity (high-capacity runners, HCR) are more physically active than their low-capacity counterparts (low-capacity runners, LCR). To test the hypothesis that physical activity counters metabolic thriftiness, we measured physical activity and weight loss during three weeks of 50% calorie restriction (CR) in the HCR and LCR rat lines. At baseline, HCR ate more and were more active than LCR; this was seen in male rats, where LCR are considerably heavier than HCR, as well as in a set of female rats where body weight did not differ between the lines, demonstrating that this effect is consistent across sex and not secondary to body weight. We show for the first time that HCR lose more weight than LCR relative to baseline. Physical activity levels declined throughout CR, and this was more pronounced in HCR than in LCR, yet some aspects of activity remained elevated in HCR relative to LCR even during CR. This is consistent with the idea that low physical activity contributes to metabolic thriftiness during food restriction, allowing LCR to defend body mass, particularly lean mass. This has implications for physical activity during diet-induced weight loss, the genetic underpinnings of individual differences in weight loss during a diet, and the potential evolutionary opposition between metabolic thriftiness and aerobic capacity. Copyright © 2014 Elsevier Inc. All rights reserved.
    Physiology & Behavior 11/2014; 139C:303-313. DOI:10.1016/j.physbeh.2014.11.044 · 3.03 Impact Factor
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    ABSTRACT: We report automated and time efficient (2 h per sample) profiling of muscle using ultra-performance liquid chromatography (LC) coupled directly with high-definition mass spectrometry (HDMSE). Soluble proteins extracted from rat gastrocnemius (n = 10) were digested with trypsin and analysed in duplicate using a 90 min RPLC gradient. Protein identification and label-free quantitation were performed from HDMSE spectra analysed using TransOmics Informatics for Proteomics software. In total 1,514 proteins were identified. Of these, 811 had at least 3 unique peptides and were subsequently used to assess the dynamic range and precision of LC-HDMSE label-free profiling. Proteins analysed by LC-HDMSE encompass the entire complement of glycolytic, beta-oxidation and tricarboxylic acid enzymes. In addition, numerous components of the electron transport chain and protein kinases involved in skeletal muscle regulation were detected. The dynamic range of protein abundances spanned 4 orders of magnitude. The correlation between technical replicates of the 10 biological samples was R2 = 0.9961 ± 0.0036 (95% CI = 0.9940 – 0.9992) and the technical coefficient of variation averaged 7.3 ± 6.7% (95% CI = 6.87 – 7.79%). This represents the most sophisticated label-free profiling of skeletal muscle to date.This article is protected by copyright. All rights reserved
    Proteomics 10/2014; 14(20). DOI:10.1002/pmic.201400118 · 3.97 Impact Factor
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    ABSTRACT: Objectives Diabetes leads to cognitive impairment and is associated with age-related neurodegenerative diseases including Alzheimer's disease (AD). Thus, understanding diabetes-induced alterations in brain function is important for developing early interventions for neurodegeneration. Low-capacity runner (LCR) rats are obese and manifest metabolic risk factors resembling human “impaired glucose tolerance” or metabolic syndrome. We examined hippocampal function in aged LCR rats compared to their high-capacity runner (HCR) rat counterparts.Methods Hippocampal function was examined using proton magnetic resonance spectroscopy and imaging, unbiased stereology analysis, and a Y maze. Changes in the mitochondrial respiratory chain function and levels of hyperphosphorylated tau and mitochondrial transcriptional regulators were examined.ResultsThe levels of glutamate, myo-inositol, taurine, and choline-containing compounds were significantly increased in the aged LCR rats. We observed a significant loss of hippocampal neurons and impaired cognitive function in aged LCR rats. Respiratory chain function and activity were significantly decreased in the aged LCR rats. Hyperphosphorylated tau was accumulated within mitochondria and peroxisome proliferator-activated receptor-gamma coactivator 1α, the NAD+-dependent protein deacetylase sirtuin 1, and mitochondrial transcription factor A were downregulated in the aged LCR rat hippocampus.InterpretationThese data provide evidence of a neurodegenerative process in the hippocampus of aged LCR rats, consistent with those seen in aged-related dementing illnesses such as AD in humans. The metabolic and mitochondrial abnormalities observed in LCR rat hippocampus are similar to well-described mechanisms that lead to diabetic neuropathy and may provide an important link between cognitive and metabolic dysfunction.
    08/2014; 1(8). DOI:10.1002/acn3.86
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    ABSTRACT: Rats selectively bred for high- and low-capacity for running on a treadmill (HCR; LCR) also differ in wheel-running behavior, but whether wheel-running can be explained by intrinsic or adaptive brain mechanisms is not as yet understood. It is established that motivation of locomotory behavior is driven by dopaminergic transmission in mesolimbic and mesostriatal systems. However, whether voluntary wheel running is associated with enkephalinergic activity in the ventral striatum is not known. Materials & Methods 40 male (20 HCR and 20 LCR) and 40 female (20 HCR and 20 LCR) rats were randomly assigned to 3 weeks of activity wheel exposure or sedentary conditions without wheel access. After 3 weeks of activity-wheel running, rats were decapitated and brains were extracted. Coronal sections were analyzed utilizing in situ hybridization histochemistry for enkephalin (ENK) mRNA in the ventral striatum. Results HCR rats expressed less ENK than LCR rats in the nucleus accumbens among females (p<.01) and in the olfactory tubercle among both females (p<.05) and males (p<.05). There was no effect of wheel running on ENK mRNA expression. Conclusion Line differences in ENK expression in the olfactory tubercle, and possibly the nucleus accumbens, partly explain divergent wheel-running behavior. The lower striatal ENK in the HCR line is consistent with enhanced dopaminergic tone, which may explain the increased motivation for wheel running observed in the HCR line.
    Brain Research 07/2014; DOI:10.1016/j.brainres.2014.05.014 · 2.83 Impact Factor
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    ABSTRACT: Aerobic capacity/fitness significantly impacts susceptibility for fatty liver and diabetes, but the mechanisms remain unknown. Herein we utilized rats selectively bred for high (HCR) and low (LCR) intrinsic aerobic capacity to examine the mechanisms by which aerobic capacity impacts metabolic vulnerability for fatty liver following a 3-day high fat diet (HFD). Indirect calorimetry assessment of energy metabolism combined with radiolabeled dietary food was employed to examine systemic metabolism in combination with ex vivo measures of hepatic lipid oxidation. The LCR, but not HCR, displayed increased hepatic lipid accumulation in response to the HFD despite both groups increasing energy intake. However, LCR rats had a greater increase in energy intake and demonstrated greater daily weight gain and percent body fat due to HFD compared to HCR. Additionally, total energy expenditure was higher in the larger LCR. However, controlling for the difference in body weight, the LCR has lower resting energy expenditure compared to HCR. Importantly, respiratory quotient was significantly higher during the HFD in the LCR compared to HCR, suggesting reduced whole-body lipid utilization in the LCR. This was confirmed by the observed lower whole-body dietary fatty acid oxidation in LCR compared to HCR. Further, LCR liver homogenate and isolated mitochondria showed lower complete fatty acid oxidation compared to HCR. Conclusion: Rats bred for low intrinsic aerobic capacity show greater susceptibility for dietary-induced hepatic steatosis, which is associated with a lower energy expenditure and reduced whole-body and hepatic mitochondrial lipid oxidation.
    AJP Endocrinology and Metabolism 06/2014; 307(4). DOI:10.1152/ajpendo.00093.2014 · 4.09 Impact Factor
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    ABSTRACT: Trainability is important in elite sport and in recreational physical activity, and the wide range for response to training is largely dependent on genotype. In this study, we compare a newly developed rat model system selectively bred for low and high gain in running distance from aerobic training to test whether genetic segregation for trainability associates with differences in factors associated with mitochondrial biogenesis. Low response trainer (LRT) and high response trainer (HRT) rats from generation 11 of artificial selection were trained five times a week, 30 min per day for 3 months at 70 % VO2max to study the mitochondrial molecular background of trainability. As expected, we found significant differential for the gain in running distance between LRT and HRT groups as a result of training. However, the changes in VO2max, COX-4, redox homeostasis associated markers (reactive oxygen species (ROS)), silent mating-type information regulation 2 homolog (SIRT1), NAD(+)/NADH ratio, proteasome (R2 subunit), and mitochondrial network related proteins such as mitochondrial fission protein 1 (Fis1) and mitochondrial fusion protein (Mfn1) suggest that these markers are not strongly involved in the differences in trainability between LRT and HRT. On the other hand, according to our results, we discovered that differences in basal activity of AMP-activated protein kinase alpha (AMPKα) and differential changes in aerobic exercise-induced responses of citrate synthase, carbonylated protein, peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1-α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), and Lon protease limit trainability between these selected lines. From this, we conclude that mitochondrial biogenesis-associated factors adapt differently to aerobic exercise training in training sensitive and training resistant rats.
    Pflügers Archiv - European Journal of Physiology 06/2014; 467(4). DOI:10.1007/s00424-014-1554-7 · 3.07 Impact Factor
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    ABSTRACT: Obesity alters the therapeutic window of sedative/hypnotic drugs and increases the probability of respiratory complications. The current experiments used an established rodent model of obesity to test the hypothesis that the sedative/hypnotic drugs eszopiclone and dexmedetomidine alter ventilation differentially in obese rats compared with lean/fit rats. This study used a within-groups/between-groups experimental design. University of Michigan. Experiments were conducted using lean/fit rats (n = 21) and obese rats (n = 21) that have features of metabolic syndrome. Breathing was measured with whole-body plethysmography after systemic administration of vehicle (control), the nonbenzodiazepine, benzodiazepine site agonist eszopiclone, or the alpha-2 adrenergic receptor agonist dexmedetomidine. Data were analyzed using two-way analysis of variance and appropriate post hoc comparisons. At baseline, the obese/metabolic syndrome rats had increased respiratory rates (21.6%), lower tidal volumes/body weight (-24.1%), and no differences in minute ventilation compared to lean/fit rats. In the obese rats, respiratory rate was decreased by dexmedetomidine (-29%), but not eszopiclone. In the lean and the obese rats, eszopiclone decreased tidal volume (-12%). Both sedative/hypnotic drugs caused a greater decrease in minute ventilation in the obese (-26.3%) than lean (-18%) rats. Inspiratory flow rate (VT / TI) of the obese rats was decreased by dexmedetomidine (-10.6%) and eszopiclone (-18%). Duty cycle (TI / TTOT) in both rat lines was decreased by dexmedetomidine (-16.5%) but not by eszopiclone. Dexmedetomidine, in contrast to eszopiclone, decreased minute ventilation in the obese/metabolic syndrome rats by depressing both duty cycle and inspiratory flow rate. The results show for the first time that the obese phenotype differentially modulates the respiratory effects of eszopiclone and dexmedetomidine. These differences in breathing are consistent with previously documented differences in sleep between lean/fit and obese rats. These findings also encourage future studies of obese/metabolic syndrome rats that quantify the effect of sedative/hypnotic drugs on respiratory mechanics as well as hypoxic and hypercapnic ventilatory responses. Continued findings of favorable homology between obese humans and rodents will support the interpretation that these obese rats offer a unique animal model for mechanistic studies. Filbey WA, Sanford DT, Baghdoyan HA, Koch LG, Britton SL, Lydic R. Eszopiclone and dexmedetomidine depress ventilation in obese rats with features of metabolic syndrome. SLEEP 2014;37(5):871-880.
    Sleep 05/2014; 37(5):871-880. DOI:10.5665/sleep.3650 · 5.06 Impact Factor
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    ABSTRACT: Profiling of protein species is important because gene polymorphisms, splice variations and post-translational modifications may combine and give rise to multiple protein species that have different effects on cellular function. Two-dimensional gel electrophoresis is one of the most robust methods for differential analysis of protein species, but bioinformatic interrogation is challenging because the consequences of changes in the abundance of individual protein species on cell function are unknown and cannot be predicted. We conducted DIGE of soleus muscle from male and female rats artificially selected as either high- or low-capacity runners (HCR and LCR, respectively). In total 696 protein species were resolved and LC-MS/MS identified proteins in 337 spots. Forty protein species were differentially (P<0.05, FDR<10 %) expressed between HCR and LCR and conditional independence mapping found distinct networks within these data, which brought insight beyond that achieved by functional annotation. Protein disulfide isomerase A3 emerged as a key node segregating with differences in aerobic capacity and unsupervised bibliometric analysis highlighted further links to signal transducer and activator of transcription 3, which were confirmed by western blotting. Thus, conditional independence mapping is a useful technique for interrogating DIGE data that is capable of highlighting latent features. Quantitative proteome profiling revealed there is little or no sexual dimorphism in the skeletal muscle response to artificial selection on running capacity. Instead we found noncanonical STAT3 signalling may be associated with low exercise capacity and skeletal muscle insulin resistance. Importantly, this discovery was made using unsupervised multivariate association mapping and bibliometric network analyses. This allowed our interpretation of the findings to be guided by patterns within the data rather than our preconceptions about which proteins or processes are of greatest interest. Moreover, we demonstrate this novel approach can be applied to 2D gel analysis, which is unsurpassed in its ability to profile protein species but currently has few dedicated bioinformatic tools.
    Journal of proteomics 04/2014; 106. DOI:10.1016/j.jprot.2014.04.015 · 3.93 Impact Factor
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    ABSTRACT: A high-calorie diet accompanied by low levels of physical activity (PA) accounts for the widespread prevalence of obesity today. Yet, some people remain lean even in this obesogenic environment. Here, we investigate the cause for this exception. A key trait that predicts high PA in both humans and laboratory rodents is intrinsic aerobic capacity. Rats artificially selected as high capacity runners (HCR) are lean and consistently more physically active than their low- capacity runner (LCR) counterparts; this applies to both males and females. Here, we demonstrate that HCR show heightened total energy expenditure (TEE) and hypothesize that this is due to higher non-resting energy expenditure (NREE). After matching for body weight and lean mass, female HCR consistently had heightened non-resting EE, but not resting EE, compared to female LCR. Because of the dominant role of skeletal muscle in non-resting EE, we examined muscle energy use. We found that lean female HCR had higher muscle heat dissipation during activity, explaining their low economy of activity and high activity EE. This may be due to the amplified skeletal muscle expression levels of proteins involved in EE, and reduced expression levels of proteins involved in energy conservation, in HCR relative to LCR. This is also associated with an increased sympathetic drive to skeletal muscle in HCR compared to LCR. We find little support for the hypothesis that resting metabolic rate is correlated with maximal aerobic capacity if body size and composition are fully considered; rather, the critical factor appears to be activity thermogenesis.
    AJP Endocrinology and Metabolism 01/2014; 306(6). DOI:10.1152/ajpendo.00555.2013 · 4.09 Impact Factor

Publication Stats

2k Citations
455.82 Total Impact Points

Institutions

  • 2005–2015
    • University of Michigan
      • • Department of Anesthesiology
      • • Department of Physical Medicine and Rehabilitation
      • • Molecular and Behavioral Neuroscience Institute
      Ann Arbor, Michigan, United States
    • University of Colorado at Boulder
      Boulder, Colorado, United States
  • 2013
    • University of California, San Francisco
      • Department of Anesthesia and Perioperative Care
      San Francisco, California, United States
  • 2008–2013
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States
    • Norwegian University of Science and Technology
      • Department of Circulation and Medical Imaging
      Trondheim, Sor-Trondelag Fylke, Norway
  • 2012
    • RMIT University
      • School of Medical Sciences
      Melbourne, Victoria, Australia
    • Kent State University
      • Department of Biological Sciences
      Kent, OH, United States
  • 2010
    • Melbourne Institute of Technology
      Melbourne, Victoria, Australia
  • 2009
    • U.S. Army Institute of Surgical Research
      Houston, Texas, United States
  • 1999–2007
    • Medical University of Ohio at Toledo
      Toledo, Ohio, United States
  • 2003
    • University of California, San Diego
      • Department of Medicine
      San Diego, California, United States