Samuel M Poloyac

University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Are you Samuel M Poloyac?

Claim your profile

Publications (68)251.94 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Emerging evidence has suggested that patients experiencing aneurysmal subarachnoid hemorrhage (aSAH) develop vascular dysregulation as a potential contributor to poor outcomes. Preclinical studies have implicated the novel microvascular constrictor, 20-hydroxyeicosatetraenoic acid (20-HETE) in aSAH pathogenesis, yet the translational relevance of 20-HETE in patients with aSAH is largely unknown. The goal of this research was to determine the relationship between 20-HETE cerebrospinal fluid (CSF) levels, gene variants in 20-HETE synthesis, and acute/long-term aSAH outcomes. In all, 363 adult patients (age 18 to 75) with aSAH were prospectively recruited from the University of Pittsburgh Medical Center neurovascular Intensive Care Unit. Patients were genotyped for polymorphic variants and cytochrome P450 (CYP)-eicosanoid CSF levels were measured over 14 days. Outcomes included delayed cerebral ischemia (DCI), clinical neurologic deterioration (CND), and modified Rankin Scores (MRS) at 3 and 12 months. Patients with CND and unfavorable 3-month MRS had 2.2- and 2.7-fold higher mean 20-HETE CSF levels, respectively. Patients in high/moderate 20-HETE trajectory groups (35.7%) were 2.5-, 2.1-, 3.1-, 3.3-, and 2.1-fold more likely to have unfavorable MRS at 3 months, unfavorable MRS at 12 months, mortality at 3 months, mortality at 12 months, and CND, respectively. These results showed that 20-HETE is associated with acute and long-term outcomes and suggest that 20-HETE may be a novel target in aSAH.Journal of Cerebral Blood Flow & Metabolism advance online publication, 29 April 2015; doi:10.1038/jcbfm.2015.75.
    Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 04/2015; DOI:10.1038/jcbfm.2015.75 · 5.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Despite decades of basic and clinical research, treatments to improve outcomes after traumatic brain injury (TBI) are limited. However, based on the recent recognition of the prevalence of mild TBI, and its potential link to neurodegenerative disease, many new and exciting secondary injury mechanisms have been identified and several new therapies are being evaluated targeting both classic and novel paradigms. This includes a robust increase in both preclinical and clinical investigations. Using a mechanism-based approach the authors define the targets and emerging therapies for TBI. They address putative new therapies for TBI across both the spectrum of injury severity and the continuum of care, from the field to rehabilitation. They discussTBI therapy using 11 categories, namely, (1) excitotoxicity and neuronal death, (2) brain edema, (3) mitochondria and oxidative stress, (4) axonal injury, (5) inflammation, (6) ischemia and cerebral blood flow dysregulation, (7) cognitive enhancement, (8) augmentation of endogenous neuroprotection, (9) cellular therapies, (10) combination therapy, and (11) TBI resuscitation. The current golden age of TBI research represents a special opportunity for the development of breakthroughs in the field. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
    Seminars in Neurology 02/2015; 35(1):83-100. DOI:10.1055/s-0035-1544237 · 1.78 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Splicing factors (SFs) coordinate nuclear intron/exon splicing of RNA. Splicing factor disturbances can cause cell death. RNA binding motif 5 (RBM5) and 10 (RBM10) promote apoptosis in cancer cells by activating detrimental alternative splicing of key death/survival genes. The role(s) of RBM5/10 in neurons has not been established. Here, we report that RBM5 knockdown in human neuronal cells decreases caspase activation by staurosporine. In contrast, RBM10 knockdown augments caspase activation. To determine whether brain injury alters RBM signaling, we measured RBM5/10 protein in mouse cortical/hippocampus homogenates after controlled cortical impact (CCI) traumatic brain injury (TBI) plus hemorrhagic shock (CCI+HS). The RBM5/10 staining was higher 48 to 72 hours after injury and appeared to be increased in neuronal nuclei of the hippocampus. We also measured levels of other nuclear SFs known to be essential for cellular viability and report that splicing factor 1 (SF1) but not splicing factor 3A (SF3A) decreased 4 to 72 hours after injury. Finally, we confirm that RBM5/10 regulate protein expression of several target genes including caspase-2, cellular FLICE-like inhibitory protein (c-FLIP), LETM1 Domain-Containing Protein 1 (LETMD1), and amyloid precursor-like protein 2 (APLP2) in neuronal cells. Knockdown of RBM5 appeared to increase expression of c-FLIP(s), LETMD1, and APLP2 but decrease caspase-2.Journal of Cerebral Blood Flow & Metabolism advance online publication, 14 January 2015; doi:10.1038/jcbfm.2014.242.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Biochemical mediators alter cerebral perfusion and have been implicated in delayed cerebral ischemia (DCI) and poor outcomes after aneurysmal subarachnoid hemorrhage (aSAH). Estrogens (estrone [E1] and estradiol [E2]) are mediators with neuroprotective properties that could play a role in DCI. This study explored associations between plasma estrogen levels and outcomes following aSAH. Plasma samples from 1-4, 4-6, and 7-10 days after hemorrhage from 99 adult aSAH patients were analyzed for estrogen levels using liquid chromatography tandem mass spectrometry. DCI was operationalized as radiographic/ultrasonic evidence of impaired cerebral blood flow accompanied by neurological deterioration. Outcomes were assessed using the Modified Rankin Scale at 3 and 12 months after hemorrhage. Statistical analysis included correlation, regression, and group-based trajectory. Higher E1 and E2 levels were associated with higher Hunt and Hess grade (E1, p = .01; E2, p = .03), the presence of DCI (E1, p = .02; E2, p = .02), and poor 3-month outcomes (E1, p = .002; E2, p = .002). Trajectory analysis identified distinct populations over time for E1 (61% E1 high) and E2 (68% E2 high). Patients in higher trajectory groups had higher Fisher grades (E1, p = .008; E2, p = .01), more frequent DCI (E1, p = .04; E2, p = .08), and worse 3-month outcomes (E1, p = .01; E2, p = .004) than low groups. These results provide the first clinical evidence that plasma E1 and E2 concentrations are associated with severity of injury and outcomes after aSAH. © The Author(s) 2014.
    Biological Research for Nursing 12/2014; DOI:10.1177/1099800414561632 · 1.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preclinical studies show that epoxyeicosatrienoic acids (EETs) regulate cerebrovascular tone and protect against cerebral ischemia. We investigated the relationship between polymorphic genes involved in EET biosynthesis/metabolism, cytochrome P450 (CYP) eicosanoid levels, and outcomes in 363 patients with aneurysmal subarachnoid hemorrhage (aSAH). Epoxyeicosatrienoic acids and dihydroxyeicosatetraenoic acid (DHET) cerebrospinal fluid (CSF) levels, as well as acute outcomes defined by delayed cerebral ischemia (DCI) or clinical neurologic deterioration (CND), were assessed over 14 days. Long-term outcomes were defined by Modified Rankin Scale (MRS) at 3 and 12 months. CYP2C8*4 allele carriers had 44% and 36% lower mean EET and DHET CSF levels (P=0.003 and P=0.007) and were 2.2- and 2.5-fold more likely to develop DCI and CND (P=0.039 and P=0.041), respectively. EPHX2 55Arg, CYP2J2*7, CYP2C8*1B, and CYP2C8 g.36785A allele carriers had lower EET and DHET CSF levels. CYP2C8 g.25369T and CYP2C8 g.36755A allele carriers had higher EET levels. Patients with CYP2C8*2C and EPHX2 404del variants had worse long-term outcomes while those with EPHX2 287Gln, CYP2J2*7, and CYP2C9 g.816G variants had favorable outcomes. Epoxyeicosatrienoic acid levels were associated with Fisher grade and unfavorable 3-month outcomes. Dihydroxyeicosatetraenoic acids were not associated with outcomes. No associations passed Bonferroni multiple testing correction. These are the first clinical data demonstrating the association between the EET biosynthesis/metabolic pathway and the pathophysiology of aSAH.Journal of Cerebral Blood Flow & Metabolism advance online publication, 12 November 2014; doi:10.1038/jcbfm.2014.195.
    Journal of Cerebral Blood Flow & Metabolism 11/2014; 35(2). DOI:10.1038/jcbfm.2014.195 · 5.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Fatty liver disease is an emerging public health problem without effective therapies, and chronic hepatic inflammation is a key pathologic mediator in its progression. Cytochrome P450 (CYP) epoxygenases metabolize arachidonic acid to biologically active epoxyeicosatrienoic acids (EETs), which have potent anti-inflammatory effects. Although promoting the effects of EETs elicits anti-inflammatory and protective effects in the cardiovascular system, the contribution of CYP-derived EETs to the regulation of fatty liver disease-associated inflammation and injury is unknown. Using the atherogenic diet model of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD/NASH), our studies demonstrated that induction of fatty liver disease significantly and preferentially suppresses hepatic CYP epoxygenase expression and activity, and both hepatic and circulating levels of EETs in mice. Furthermore, mice with targeted disruption of Ephx2 (the gene encoding soluble epoxide hydrolase) exhibited restored hepatic and circulating EET levels and a significantly attenuated induction of hepatic inflammation and injury. Collectively, these data suggest that suppression of hepatic CYP-mediated EET biosynthesis is an important pathological consequence of fatty liver disease-associated inflammation, and that the CYP epoxygenase pathway is a central regulator of the hepatic inflammatory response in NAFLD/NASH. Future studies investigating the utility of therapeutic strategies that promote the effects of CYP-derived EETs in NAFLD/NASH are warranted.
    PLoS ONE 10/2014; 9(10):e110162. DOI:10.1371/journal.pone.0110162 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To examine the relationship between regional cerebral oxygen saturation (rSO2), delayed cerebral ischaemia (DCI), and outcomes after aneurysmal subarachnoid haemorrhage (aSAH).
    Intensive & critical care nursing: the official journal of the British Association of Critical Care Nurses 06/2014; DOI:10.1016/j.iccn.2014.05.001
  • [Show abstract] [Hide abstract]
    ABSTRACT: Aneurysmal subarachnoid hemorrhage is a type of stroke with high morbidity and mortality. Increased endothelin-1 (ET-1) levels have been associated with increased risk of cerebral vasospasm, which is associated with increased morbidity. The purpose of this study was to investigate the relationships between ET-1 genotypes and ET-1 protein levels in cerebrospinal fluid (CSF) measured 72 hr before angiographic vasospasm measurement in subjects at high risk of cerebral vasospasm. Specifically, this study evaluated the differences between variant positive and variant negative groups of nine different ET-1 single-nucleotide polymorphisms (SNPs) in relationship with the ET-1 protein exposure rate. The CSF ET-1 protein levels were quantified using enzyme-linked immunosorbent assay. One functional SNP and eight ET-1 tagging SNPs were selected because they represent genetic variability in the entire ET-1 gene. The variant negative group of SNP rs2070699 was associated with a significantly higher ET-1 exposure rate than the variant positive group (p = 0.004), while the variant positive group of the rs5370 group showed a trend toward association with a higher ET-1 exposure rate (p = 0.051). Other SNPs were not informative. This is the first study to show differences in ET-1 exposure rate 72 hr before angiography in relation to ET-1 genotypes. These exploratory findings need to be replicated in a larger study; if replicated, these differences in genotypes may be a way to inform clinicians of those patients at a higher risk of increased ET-1 protein levels, which may lead to a higher risk of angiographic vasospasm.
    Biological Research for Nursing 05/2014; 17(2). DOI:10.1177/1099800414536261 · 1.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The central role of mitochondria in metabolic pathways and in cell-death mechanisms requires sophisticated signalling systems. Essential in this signalling process is an array of lipid mediators derived from polyunsaturated fatty acids. However, the molecular machinery for the production of oxygenated polyunsaturated fatty acids is localized in the cytosol and their biosynthesis has not been identified in mitochondria. Here we report that a range of diversified polyunsaturated molecular species derived from a mitochondria-specific phospholipid, cardiolipin (CL), is oxidized by the intermembrane-space haemoprotein, cytochrome c. We show that a number of oxygenated CL species undergo phospholipase A2-catalysed hydrolysis and thus generate multiple oxygenated fatty acids, including well-known lipid mediators. This represents a new biosynthetic pathway for lipid mediators. We demonstrate that this pathway, which includes the oxidation of polyunsaturated CLs and accumulation of their hydrolysis products (oxygenated linoleic, arachidonic acids and monolysocardiolipins), is activated in vivo after acute tissue injury.
    Nature Chemistry 05/2014; 6(6). DOI:10.1038/nchem.1924 · 23.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cytochrome P450 (CYP) 4A and 4F enzymes metabolize arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). Although CYP4A-derived 20-HETE is known to have prohypertensive and proangiogenic properties, the effects of CYP4F-derived metabolites are not well characterized. To investigate the role of CYP4F2 in vascular disease, we generated mice with endothelial expression of human CYP4F2 (Tie2-CYP4F2-Tr). LC/MS/MS analysis revealed 2-foldincreases in 20-HETE levels in tissues and endothelial cells (ECs), relative to wild-type (WT) controls. Tie2-CYP4F2-Tr ECs demonstrated increases in growth (267.1±33.4 vs. 205.0±13% at 48 h) and tube formation (7.7±1.1 vs. 1.6±0.5 tubes/field) that were 20-HETE dependent and associated with up-regulation of prooxidant NADPH oxidase and proangiogenic VEGF. Increases in VEGF and NADPH oxidase levels were abrogated by inhibitors of NADPH oxidase and MAPK, respectively, suggesting the possibility of crosstalk between pathways. Interestingly, IL-6 levels in Tie2-CYP4F2-Tr mice (18.6±2.7 vs. 7.9±2.7 pg/ml) were up-regulated via NADPH oxidase- and 20-HETE-dependent mechanisms. Although Tie2-CYP4F2-Tr aortas displayed increased vasoconstriction, vasorelaxation and blood pressure were unchanged. Our findings indicate that human CYP4F2 significantly increases 20-HETE production, CYP4F2-derived 20-HETE mediates EC proliferation and angiogenesis via VEGF- and NADPH oxidase-dependent manners, and the Tie2-CYP4F2-Tr mouse is a novel model for examining the pathophysiological effects of CYP4F2-derived 20-HETE in the vasculature.-Cheng, J., Edin, M. L., Hoopes, S. L., Li, H., Bradbury, J. A., Graves, J. P., DeGraff, L. M., Lih, F. B., Garcia, V., Shaik, J. S. B., Tomer, K. B., Flake, G. P., Falck, J. R., Lee, C. R., Poloyac, S. M., Schwartzman, M. L., Zeldin, D. C. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2.
    The FASEB Journal 03/2014; 28(7). DOI:10.1096/fj.13-241927 · 5.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives To examine the relationship between regional cerebral oxygen saturation (rSO2), delayed cerebral ischaemia (DCI), and outcomes after aneurysmal subarachnoid haemorrhage (aSAH). Research Methodology Subjects (n = 163) with aSAH, age 21–75 years, and Fisher grade >1 were included in the study. Continuous rSO2 monitoring was performed for 5–10 days after injury using near-infrared spectroscopy with sensors over the frontal/temporal cortex. rSO2 < 50 indicated desaturation. DCI was defined as neurological deterioration due to impaired cerebral blood flow. Three- and 12-month functional outcomes were assessed by the modified Rankin scale (MRS) as good (0–3) and poor (4–6). Results DCI occurred in 57% of patients; of these 66% had rSO2 < 50. Overall, 56% had rSO2 < 50 on either side, 21% and 16% had poor MRS at 3 and 12 months. Subjects with rSO2 <50 were 3.25 times more likely to have DCI compared to those with rSO2 >50 (OR 3.25, 95%CI 1.58–6.69), positive predictive value (PPV) = 70%. Subjects with rSO2 <50 were 2.7 times more likely to have poor 3-month MRS compared to those with rSO2 >50 (OR 2.7, 95%CI 1.1–7.2), PPV = 70%. Conclusions These results suggest that NIRS has the potential for detecting DCI after aSAH. This potential needs to be further explored in a larger prospective study.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The metabolites of arachidonic acid (AA) produced from the cyclooxygenase (COX) pathway, collectively termed as prostanoids, and from the CYP 450 pathway, eicosanoids, have been implicated in various neuro-degenerative and neuroinflammatory diseases. This study developed a quantitative UPLC-MS/MS method to simultaneously measure 11 prostanoids including prostaglandins and cyclopentenone metabolites in the rat brain cortical tissue. Linear calibration curves ranging from 0.104 to 33.3ng/ml were validated. The inter-day and intra-day variance for all metabolites was less than 15%. The extraction recovery efficiency and matrix (deionized water) effects measured at 12.5ng/ml (750pg on column) ranged from 88 to 100% and 3 to 14%, respectively, with CV% values below 20%. Additionally, applying the processing and extraction conditions of this method to our previous CYP450 eicosanoids method resulted in overall improvement in extraction recovery and reduction in matrix effects at low (0.417ng/ml) and high (8.33ng/ml) concentrations. In rat brain cortical tissue samples, concentrations of prostanoids ranged from 10.2 to 937pmol/g wet tissue and concentration of eicosanoids ranged from 2.23 to 793pmol/g wet tissue. These data demonstrate that the successive measurement of prostanoids and eicosanoids from a single extracted sample of rat brain tissue can be achieved with a UPLC-MS/MS system and that this method is necessary for evaluation of these metabolites to delineate their role in various neuroinflammatory and cerebrovascular disorders.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 11/2013; 945-946C:207-216. DOI:10.1016/j.jchromb.2013.11.041 · 2.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: Preclinical and clinical studies have suggested that therapeutic hypothermia, while decreasing neurologic injury, may also lead to drug toxicity that may limit its benefit. Cooling decreases cytochrome P450 (CYP)-mediated drug metabolism, and limited clinical data suggest that drug levels are elevated. Fosphenytoin is metabolized by cytochrome P450 2C, has a narrow therapeutic range, and is a commonly used antiepileptic medication. The objective of this study was to evaluate the impact of therapeutic hypothermia on phenytoin levels and pharmacokinetics in children with severe traumatic brain injury. DESIGN: Pharmacokinetic analysis of subjects participating in a multicenter randomized phase III study of therapeutic hypothermia for severe traumatic brain injury. SETTING: ICU at the Children's Hospital of Pittsburgh. PATIENTS: Nineteen children with severe traumatic brain injury. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A sum of 121 total and 114 free phenytoin levels were evaluated retrospectively in 10 hypothermia-treated and nine normothermia-treated children who were randomized to 48 hours of cooling to 32-33°C followed by slow rewarming or controlled normothermia. Drug dosing, body temperatures, and demographics were collected during cooling, rewarming, and posttreatment periods (8 d). A trend toward elevated free phenytoin levels in the hypothermia group (p=0.051) to a median of 2.2 mg/L during rewarming was observed and was not explained by dosing differences. Nonlinear mixed-effects modeling incorporating both free and total levels demonstrated that therapeutic hypothermia specifically decreased the time-variant component of the maximum velocity of phenytoin metabolism (Vmax) 4.6-fold (11.6-2.53 mg/hr) and reduced the overall Vmax by ~50%. Simulations showed that the increased risk for drug toxicity extends many days beyond the end of the cooling period. CONCLUSIONS: Therapeutic hypothermia significantly reduces phenytoin elimination in children with severe traumatic brain injury leading to increased drug levels for an extended period of time after cooling. Pharmacokinetic interactions between hypothermia and medications should be considered when caring for children receiving this therapy.
    Critical Care Medicine 10/2013; 41(10):2379-87. DOI:10.1097/CCM.0b013e318292316c. · 6.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background and purpose: Soluble epoxide hydrolase (sEH) diminishes vasodilatory and neuroprotective effects of epoxyeicosatrienoic acids by hydrolyzing them to inactive dihydroxy metabolites. The primary goals of this study were to investigate the effects of acute sEH inhibition by t-AUCB on infarct volume, functional outcome, and changes in cerebral blood flow (CBF) in a rat model of ischemic stroke. Methods: Focal cerebral ischemia was induced in rats for 90 min followed by reperfusion. At the end of 24 h after reperfusion rat were euthanized for infarct volume assessment by TTC staining. Brain cortical sEH activity was assessed by UPLC-MS/MS. Functional outcome at 24, and 48 h after reperfusion was evaluated by arm flexion, and sticky-tape tests. Changes in CBF were assessed by ASL-MRI at baseline, during ischemia, and at 180 min after reperfusion. Neuroprotective effects of t-AUCB were evaluated in primary rat neuronal cultures by Cytotox-Flour kit and Propidium Iodide staining. Results: t-AUCB significantly reduced cortical infarct volume by 35% (14.5±2.7% vs 41.5±4.5%), elevated cumulative EETs/DHETs ratio in brain cortex by two fold (4.40±1.89 vs 1.97±0.85), and improved functional outcome in arm-flexion test (day 1: 3.28±0.5 s vs 7.50±0.9 s; day 2: 1.71±0.4 s vs 5.28±0.5 s) when compared to the vehicle-treated group. t-AUCB significantly reduced neuronal cell death in a dose dependent manner (vehicle:70.9±7.1% vs t-AUCB0.1µM: 58±5.11% vs t-AUCB0.5µM: 39.9±5.8%). Conclusions: These findings suggest that t-AUCB may exert its neuroprotective effects by affecting multiple components of neurovascular unit including neurons, astrocytes and microvascular flow.
    AJP Heart and Circulatory Physiology 09/2013; 305(11). DOI:10.1152/ajpheart.00471.2013 · 4.01 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Prostaglandin D2 (PGD2) is the most abundant prostaglandin in brain but its effect on neuronal cell death is complex and not completely understood. PGD2 may modulate neuronal cell death via activation of DP receptors or its metabolism to the cyclopentenone prostaglandins (CyPGs) PGJ2, △(12)-PGJ2 and 15-deoxy-△(12,14)-PGJ2, inducing cell death independently of prostaglandin receptors. This study aims to elucidate the effect of PGD2 on neuronal cell death and its underlying mechanisms. PGD2 dose-dependently induced cell death in rat primary neuron-enriched cultures in concentrations of ≥ 10μM, and this effect was not reversed by treatment with either DP1 or DP2 receptor antagonists. Antioxidants N-acetylcysteine (NAC) and glutathione which contain sulfhydryl groups that can bind to CyPGs, but not ascorbate or tocopherol, attenuated PGD2-induced cell death. Conversion of PGD2 to CyPGs was detected in neuronal culture medium; treatment with these CyPG metabolites alone exhibited effects similar to those of PGD2, including apoptotic neuronal cell death and accumulation of ubiquitinated proteins. Disruption of lipocalin-type prostaglandin D synthase (L-PGDS) protected neurons against hypoxia. These results support the hypothesis that PGD2 elicits its cytotoxic effects through its bioactive CyPG metabolites rather than DP receptor activation in primary neuronal culture.
    NeuroToxicology 08/2013; DOI:10.1016/j.neuro.2013.08.001 · 3.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Cyclopentenone prostaglandins have been identified as potential neurotoxic agents in the setting of hypoxia-ischemia. Cyclooxygenase-2 (COX-2), the upstream enzyme responsible for prostaglandin production is upregulated following hypoxic-ischemic brain injury. However, the temporal production and concentration of cyclopentenone prostaglandins has not been described following global brain ischemia. METHODS: Global brain ischemia was induced in rats by asphyxial cardiac arrest (ACA) followed by resuscitation. Rats were sacrificed between 24 hours and 7 days following resuscitation and their brains removed. Western blot, immunohistochemistry, and mass spectroscopy were performed. A cohort of rats was pretreated with the COX-2 inhibitor SC58125. RESULTS: COX-2 is induced in hippocampus at 24 hours following ACA. Multiple prostaglandins, including cyclopentenone prostaglandin species, are increased in hippocampus as 24 hours following ACA. Prostaglandin and cyclopentenone prostaglandin concentrations are returned to baseline at 3 and 7 days post-ischemia. The COX-2 inhibitor SC58125 completely abrogates the post-ischemic increase in prostaglandins and cyclopentenone prostaglandins. CONCLUSIONS: Prostaglandins, including cyclopentenone prostaglandins, are increased in ischemic brain, peak at 24 hours and can be attenuated by the COX-2 inhibitor SC58125. These data establish the presence of potentially neurotoxic cyclopentenone prostaglandins in post-ischemic brains, thus identifying a target and therapeutic window for neuroprotective therapies.
    Brain research 04/2013; DOI:10.1016/j.brainres.2013.04.029 · 2.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Topical vaginal microbicides have been considered as a promising option for preventing the male-to-female sexual transmission of HIV, however clinical trials to date have not clearly demonstrated robust and reproducible effectiveness results. While multiple approaches may help enhance product effectiveness observed in clinical trials, increasing the drug exposure in lower genital tract tissues is a compelling option, given the difficulty in achieving sufficient drug exposure and positive correlation between tissue exposure and microbicide efficacy. Since many microbicide drug candidates are substrates of transporters and/or metabolizing enzymes, there is emerging interest in improving microbicide exposure and efficacy through local modulation of transporters and enzymes in female lower genital tract. However, no systematic information on transporter/enzyme expression is available for ectocervical and vaginal tissues of premenopausal women, the genital sites most relevant to microbicide drug delivery. The current study utilized RT-PCR to examine the mRNA expression profile of 22 transporters and 19 metabolizing enzymes in premenopausal normal human ectocervix and vagina. Efflux and uptake transporters important for antiretroviral drugs, such as P-gp, BCRP, OCT2, and ENT1, were found to be moderately or highly expressed in the lower genital tract as compared to liver. Among the metabolizing enzymes examined, most CYP isoforms were not detected while a number of UGTs such as UGT1A1 were highly expressed. Moderate to high expression of select transporters and enzymes were also observed in mouse cervix and vagina. The implications of this information on microbicide research is also discussed, including microbicide pharmacokinetics, the utilization of the mouse model in microbicide screening as well as the in vivo functional studies of cervicovaginal transporters and enzymes.
    AIDS research and human retroviruses 04/2013; DOI:10.1089/AID.2013.0032 · 2.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Cerebral infarct leads to secondary brain injury, such as cerebral vasospasm and delayed cerebral ischemia, which induces high mortality and morbidity risk in post-aneurysmal subarachnoid hemorrhage (aSAH). General therapeutic options are largely limited to treating and possible reducing impaired neurological function. Discovery of a biologic indicator associated with delayed cerebral ischemia may diminish neurological ischemic deficits by providing for better assessment and quicker treatment. PROBLEM/PURPOSE: Neuroprotective biomarkers may play a role in preventing neuronal damage and in stimulating biochemical function. Neuroglobin (NGB), an endogenous neuroprotector, may be such a biomarker. NGB increases oxygen in case of cerebral ischemia and binds with more toxic substances in neurons. This study investigates NGB protein function during the critical hours after aSAH. The hypothesis guiding this investigation is that NGB concentration is associated with cerebral infarct in the critical hours immediately after the insult. An additional hypothesis is that NGB can predict neurological outcomes. METHODS: Design: This study was a prospective biobehavioral correlational design with a healthy control group (n=25). Forty-nine consecutively selected from subjects were enrolled between 2004 and 2009 using the following inclusion criteria: 1) adults (ages 21-75 years) diagnosis with severe aSAH from a ruptured cerebral aneurysm and; 2) Hunt & Hess grade > 1 and/or Fisher score > 2. The patients were admitted to the Neuro-Vascular Intensive Care Unit (NV-ICU) at the University of Pittsburgh Medical Center (UPMC). The study was approved by the University of Pittsburgh Institutional Review Board. Sample: Subjects were primarily of female, Caucasians, mean age 53 years with damage to in the posterior communicating artery; Glasgow Coma Scores of 13-15; Hunt & Hess grade 3; and Fisher score of 3. Measures: Cerebral spinal fluid (CSF) samples were obtained from all subjects 120 hours after admission to NV_ICU. Outcomes were assessed by Glasgow Outcomes Scale (GOS), National Institute of Health Stroke Scale (NIHSS), and Modified Rankin Scale (MRS). Analysis: Laboratory techniques included the Pierce BCA Protein, human NGB ELISA kit, an Odyssey Infract Imaging System with Western Blot were used. Descriptive statistics, independent t-tests, and chi-square were used. RESULT: Total protein concentrations in the CSF were significantly (t(48) =7.562, p< 0.01) higher in aSAH subjects compared to health control (3595.73+ 2017 ng/ul vs. 318.43 + 196 ng/ul) over time. NGB concentrations were higher between 36-60 hours after the aSAH insult, with the highest peak (9 ng/dl) and decreasing at hours 120 hours (3 ng/dl). Fifteen aSAH subjects with severe infarct showed higher NGB than non-infarct subjects. Those with lower NGB had better neurological outcomes including the GOS, NIHSS, and MRS at months 3 and 12. CONCLUSIONS: NGB was found to be elevated with in the first 24 to 72 hours decreasing by 120 hours after aSAH. There were greater levels associated with more severe infarct size/volume. NGB may play a role in the dynamic of cerebral ischemia. Further investigation is needed, but screening individuals for NGB may permit early targeted intervention in the future.
    2014 Western Institute of Nursing Annual Communicating Nursing Research Conference; 04/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVES:: Pathological increases in asymmetric dimethylarginine, an endogenous nitric oxide synthase inhibitor, have been implicated in endothelial dysfunction and vascular diseases. Reduced nitric oxide early after traumatic brain injury may contribute to hypoperfusion. Currently, methods to quantify asymmetric dimethylarginine in the cerebrospinal fluid have not been fully explored. We aimed to develop and validate a method to determine asymmetric dimethylarginine in the cerebrospinal fluid of a pediatric traumatic brain injury population and to use this method to assess the effects of 1) traumatic brain injury and 2) therapeutic hypothermia on this mediator. DESIGN, SETTING, AND PATIENTS:: An ancillary study to a prospective, phase II randomized clinical trial of early hypothermia in a tertiary care pediatric intensive care unit for children with Traumatic brain injury admitted to Children's Hospital of Pittsburgh. INTERVENTIONS:: None. MEASUREMENTS AND MAIN RESULTS:: A UPLC-MS/MS method was developed and validated to quantitate asymmetric dimethylarginine. A total of 56 samples collected over 3 days with injury onset were analyzed from the cerebrospinal fluid of consented therapeutic hypothermia (n = 9) and normothermia (n = 10) children. Children undergoing diagnostic lumbar puncture (n = 5) were enrolled as controls. Asymmetric dimethylarginine was present at a quantifiable level in all samples. Mean asymmetric dimethylarginine levels were significantly increased in normothermic Traumatic brain injury children compared with that in control (0.19 ± 0.08 µmol/L and 0.11 ± 0.02 µmol/L, respectively, p = 0.01), and hypothermic children had significantly reduced mean asymmetric dimethylarginine levels (0.11 ± 0.05 µmol/L) vs. normothermic (p = 0.03) measured on day 3. Patient demographics including age, gender, and nitric oxide levels (measured as nitrite and nitrate using liquid chromatography coupled with Griess reaction) did not significantly differ between normothermia and hypothermia groups. Also, nitric oxide levels did not correlate with asymmetric dimethylarginine concentrations. CONCLUSIONS:: Asymmetric dimethylarginine levels were significantly increased in the cerebrospinal fluid of traumatic brain injury children. Early hypothermia attenuated this increase. The implications of attenuated asymmetric dimethylarginine on nitric oxide synthases activity and regional cerebral blood flow after traumatic brain injury by therapeutic hypothermia deserve future study.
    Pediatric Critical Care Medicine 02/2013; DOI:10.1097/PCC.0b013e31827212c0 · 2.33 Impact Factor
  • Samuel M Poloyac, Philip E Empey
    Pediatric Critical Care Medicine 02/2013; 14(2):228-9. DOI:10.1097/PCC.0b013e31826775cd · 2.33 Impact Factor

Publication Stats

874 Citations
251.94 Total Impact Points

Institutions

  • 2001–2015
    • University of Pittsburgh
      • • Safar Center for Resuscitation Research
      • • School of Pharmacy
      • • Pharmaceutical Sciences
      • • Department of Pediatrics
      Pittsburgh, Pennsylvania, United States
  • 1999–2001
    • University of Kentucky
      • • Department of Pharmaceutical Sciences
      • • College of Pharmacy
      Lexington, KY, United States
    • Minneapolis Veterans Affairs Hospital
      Minneapolis, Minnesota, United States