Among patients undergoing major abdominal surgery, intraoperative oliguria <0.3 ml kg -1 h -1 was significantly associated with increased risk of postoperative AKI.

The mammalian brain is highly vulnerable to oxygen deprivation, yet the mechanism underlying the brain’s sensitivity to hypoxia is incompletely understood. Hypoxia induces accumulation of hydrogen sulfide, a gas that inhibits mitochondrial respiration. Here, we show that, in mice, rats, and naturally hypoxia-tolerant ground squirrels, the sensitivity of the brain to hypoxia is inversely related to the levels of sulfide:quinone oxidoreductase (SQOR) and the capacity to catabolize sulfide. Silencing SQOR increased the sensitivity of the brain to hypoxia, whereas neuron-specific SQOR expression prevented hypoxia-induced sulfide accumulation, bioenergetic failure, and ischemic brain injury. Excluding SQOR from mitochondria increased sensitivity to hypoxia not only in the brain but also in heart and liver. Pharmacological scavenging of sulfide maintained mitochondrial respiration in hypoxic neurons and made mice resistant to hypoxia. These results illuminate the critical role of sulfide catabolism in energy homeostasis during hypoxia and identify a therapeutic target for ischemic brain injury.

BackgroundHydrogen sulfide (H2S) exhibits protective effects in various disease models including cerebral ischemia–reperfusion (I/R) injury. Nonetheless, mechanisms and identity of molecules responsible for neuroprotective effects of H2S remain incompletely defined. In the current study, we observed that thiosulfate, an oxidation product of H2S, mediates protective effects of an H2S donor compound sodium sulfide (Na2S) against neuronal I/R injury.Methods and ResultsWe observed that thiosulfate in cell culture medium is not only required but also sufficient to mediate cytoprotective effects of Na2S against oxygen glucose deprivation and reoxygenation of human neuroblastoma cell line (SH‐SY5Y) and murine primary cortical neurons. Systemic administration of sodium thiosulfate (STS) improved survival and neurological function of mice subjected to global cerebral I/R injury. Beneficial effects of STS, as well as Na2S, were associated with marked increase of thiosulfate, but not H2S, in plasma and brain tissues. These results suggest that thiosulfate is a circulating “carrier” molecule of beneficial effects of H2S. Protective effects of thiosulfate were associated with inhibition of caspase‐3 activity by persulfidation at Cys163 in caspase‐3. We discovered that an SLC13 family protein, sodium sulfate cotransporter 2 (SLC13A4, NaS‐2), facilitates transport of thiosulfate, but not sulfide, across the cell membrane, regulating intracellular concentrations and thus mediating cytoprotective effects of Na2S and STS.ConclusionsThe protective effects of H2S are mediated by thiosulfate that is transported across cell membrane by NaS‐2 and exerts antiapoptotic effects via persulfidation of caspase‐3. Given the established safety track record, thiosulfate may be therapeutic against ischemic brain injury.

Aims: In addition to nitric oxide and carbon monoxide, hydrogen sulfide (H 2 S) is an endogenously synthesized gaseous molecule that acts as an important signaling molecule in the living body. Transcription factor hypoxiainducible factor 1 (HIF-1) is known to respond to intracellular reduced oxygen (O 2 ) availability, which is regulated by an elaborate balance between O 2 supply and demand. However, the effect of H 2 S on HIF-1 activity under hypoxic conditions is largely unknown in mammalian cells. In this study, we tried to elucidate the effect of H 2 S on hypoxia-induced HIF-1 activation adopting cultured cells and mice. Results: The H 2 S donors sodium hydrosulfide and sodium sulfide in pharmacological concentrations reversibly reduced cellular O 2 consumption and inhibited hypoxia-but not anoxia-induced HIF-1a protein accumulation and expression of genes downstream of HIF-1 in established cell lines. H 2 S did not affect HIF-1 activation induced by the HIF-a hydroxylases inhibitors desferrioxamine or CoCl 2 . Experimental evidence adopting von Hippel-Lindau (VHL)-or mitochondria-deficient cells indicated that H 2 S did not affect neosynthesis of HIF-1a protein but destabilized HIF-1a in a VHL-and mitochondria-dependent manner. We also demonstrate that exogenously administered H 2 S inhibited HIF-1-dependent gene expression in mice. Innovation: For the first time, we show that H 2 S modulates intracellular O 2 homeostasis and regulates activation of HIF-1 and the subsequent gene expression induced by hypoxia by using an in vitro system with established cell lines and an in vivo system in mice. Conclusions: We demonstrate that H 2 S inhibits hypoxia-induced HIF-1 activation in a VHL-and mitochondriadependent manner. Antioxid. Redox Signal. 16,[203][204][205][206][207][208][209][210][211][212][213][214][215][216]

Rapid identification of bacterial pathogens is crucial for appropriate and adequate antibiotic treatment, which significantly improves patient outcomes. 16S ribosomal RNA (rRNA) gene amplicon sequencing has proven to be a powerful strategy for diagnosing bacterial infections. We have recently established a sequencing method and bioinformatics pipeline for 16S rRNA gene analysis utilizing the Oxford Nanopore Technologies MinION™ sequencer. In combination with our taxonomy annotation analysis pipeline, the system enabled the molecular detection of bacterial DNA in a reasonable time frame for diagnostic purposes. However, purification of bacterial DNA from specimens remains a rate‐limiting step in the workflow. To further accelerate the process of sample preparation, we adopted a direct PCR strategy that amplifies 16S rRNA genes from bacterial cell suspensions without DNA purification. Our results indicate that differences in cell wall morphology significantly affect direct PCR efficiency and sequencing data. Notably, mechanical cell disruption preceding direct PCR was indispensable for obtaining an accurate representation of the specimen bacterial composition. Furthermore, 16S rRNA gene analysis of mock polymicrobial samples indicated that primer sequence optimization is required to avoid preferential detection of particular taxa and to cover a broad range of bacterial species. This study establishes a relatively simple workflow for rapid bacterial identification via MinION™ sequencing, which reduces the turnaround time from sample to result, and provides a reliable method that may be applicable to clinical settings.

Rationale The regulation of calcium (Ca2+) homeostasis by beta-adrenergic receptor (βAR) activation provides the essential underpinnings of sympathetic regulation of myocardial function as well as a basis for understanding molecular events that result in hypertrophic signaling and heart failure. Sympathetic stimulation of the βAR not only induces protein phosphorylation but also activates nitric oxide (NO)-dependent signaling, which modulates cardiac contractility. Nonetheless, the role of NO in βAR-dependent regulation of Ca2+ handling has not yet been explicated fully. Objective To elucidate the role of protein S-nitrosylation, a major transducer of NO bioactivity, on βAR-dependent alterations in cardiomyocyte Ca2+ handling and hypertrophy. Methods and Results Using transgenic mice to titrate the levels of protein SNO, we uncovered major roles for protein S-nitrosylation generally, and for phospholamban (PLN) and cardiac troponin C (cTnC) S-nitrosylation in particular, in βAR-dependent regulation of Ca2+ homeostasis. Notably, S-nitrosylation of PLN consequent upon βAR stimulation is necessary for its inhibitory pentamerization of PLN, which activates sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) and increases cytosolic Ca2+ transients. Coincident S-nitrosylation of cTnC decreases myocardial sensitivity to Ca2+. During chronic adrenergic stimulation, global reductions in cellular S-nitrosylation mitigate hypertrophic signaling resulting from Ca2+ overload. Conclusions S-nitrosylation operates in concert with phosphorylation to regulate many cardiac Ca2+-handling proteins, including PLN and cTnC, thereby playing an essential and previously unrecognized role in cardiac Ca2+ homeostasis. Manipulation of the S-nitrosylation level may prove therapeutic in heart failure.

Cigarette smoke (CS) is a major contributor to the development of a large number of fatal and debilitating disorders. However, the precise molecular mechanisms underlying the effects of CS in lung disease are largely unknown. To elucidate these pathophysiological processes, we examined the in vitro and in vivo effects of CS extract (CSE) and CS on the transcription factor, hypoxia-inducible factor 1 (HIF-1). CSE induced concentration- and time-dependent accumulation of HIF-1α protein in human lung epithelial-like cells under non-hypoxic conditions. Genes upregulated by HIF-1, including vascular endothelial growth factor and regulated in development and DNA damage response 1, both of which are involved in smoking-induced emphysematous changes, were increased by CSE treatment under non-hypoxic conditions in vitro and in vivo. Further investigation revealed that reactive oxygen species were generated in cells exposed to CSE and were required for CSE-mediated induction of HIF-1α protein, as was activation of phosphoinositide 3-kinase and mitogen-activated protein kinase pathways. In conclusion, we demonstrated that CSE and CS induced HIF-1 activation in vitro and in vivo, respectively. The evidence warrants further investigation to indicate that HIF-1 plays an important role in CS-induced gene expression, which is deeply involved in pulmonary cellular stress and small airway remodelling.

BackgroundGlial cells, including microglia and astrocytes, are considered the primary source of proinflammatory cytokines in the brain. Immune insults stimulate glial cells to secrete proinflammatory cytokines that modulate the acute systemic response, which includes fever, behavioral changes, and hypothalamic-pituitary-adrenal (HPA) axis activation. We investigated the effect of general anesthetics on proinflammatory cytokine expression in the primary cultured glial cells, the microglial cell line BV-2, the astrocytic cell line A-1 and mouse brain. Methodology/Principal FindingsPrimary cultured glial cells were exposed to lipopolysaccharide (LPS) in combination with general anesthetics including isoflurane, pentobarbital, midazolam, ketamine, and propofol. Following this treatment, we examined glial cell expression of the proinflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α). LPS-induced expression of IL-1β mRNA and protein were significantly reduced by all the anesthetics tested, whereas IL-6 and TNF-α mRNA expression was unaffected. The anesthetics suppressed LPS-induced extracellular signal-regulated kinase 1/2 (ERK 1/2) phosphorylation, but did not affect nuclear factor-kappaB and activator protein-1 activation. The same effect was observed with BV-2, but not with A-1 cells. In the mouse experiments, LPS was injected intraperitoneally, and isoflurane suppressed IL-1β in the brain and adrenocorticotropic hormone in plasma, but not IL-1β in plasma.Conclusions/SignificanceTaken together, our results indicate that general anesthetics inhibit LPS-induced IL-1β upregulation in glial cells, particularly microglia, and affects HPA axis participation in the stress response.