Kazuhiro Shirozu

Cystathionine γ-Lyase deficiency protects mice from Galactosamine/lipopolysaccharide-induced acute liver failure

AIMS Acute liver failure (ALF) is a fatal syndrome attributed to massive hepatocyte death. Hydrogen sulfide (H2S) has been reported to exert cytoprotective or cytotoxic effects. Here, we examined the role of cystathionine γ-lyase (CSE, an enzyme produces H2S) in ALF induced by D-Galactosamine (GalN) and lipopolysaccharide (LPS). RESULTS Wild-type (WT) mice exhibited high mortality rate, prominent liver injury, and increased plasma alanine aminotransferase levels after GalN/LPS challenge. Congenital deficiency or chemical inhibition of CSE by DL-propargylglycine attenuated GalN/LPS-induced liver injury. CSE deficiency markedly improved survival rate and attenuated GalN/LPS-induced upregulation of inflammatory cytokines and activation of caspase 3 and poly (ADP-ribose) polymerase (PARP) in the liver. CSE deficiency protected primary hepatocytes from GalN/tumor necrosis factor-α (TNF-α)-induced cell death without affecting LPS-induced TNF-α production from primary peritoneal macrophages. Beneficial effects of CSE deficiency were associated with markedly elevated homocysteine and thiosulfate levels, upregulation of NF-E2 p45-related factor 2 (Nrf2) and antioxidant proteins, activation of Akt-dependent anti-apoptotic signaling, and inhibition of GalN/LPS-induced JNK phosphorylation in the liver. Finally, administration of sodium thiosulfate (STS) attenuated GalN/LPS-induced liver injury via activation of Akt- and Nrf2-dependent signaling and inhibition of GalN/LPS-induced JNK phosphorylation in WT mice. INNOVATION These results suggest that inhibition of CSE or administration of STS prevents acute inflammatory liver failure by augmenting thiosulfate levels and upregulating antioxidant and anti-apoptotic defense in the liver. CONCLUSION Congenital deficiency or chemical inhibition of CSE increases thiosulfate levels in the liver and prevents ALF at least in part by augmentation of antioxidant and anti-apoptotic mechanisms.

Beneficial effects of nitric oxide on outcomes after cardiac arrest and cardiopulmonary resuscitation in hypothermia-treated mice

Background:Therapeutic hypothermia (TH) improves neurological outcomes after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Although nitric oxide prevents organ injury induced by ischemia and reperfusion, role of nitric oxide during TH after CPR remains unclear. In this article, the authors examined the impact of endogenous nitric oxide synthesis on the beneficial effects of hypothermia after CA/CPR. The authors also examined whether or not inhaled nitric oxide during hypothermia further improves outcomes after CA/CPR in mice treated with TH. Methods:Wild-type mice and mice deficient for nitric oxide synthase 3 (NOS3−/−) were subjected to CA at 37°C and then resuscitated with chest compression. Body temperature was maintained at 37°C (normothermia) or reduced to 33°C (TH) for 24 h after resuscitation. Mice breathed air or air mixed with nitric oxide at 10, 20, 40, 60, or 80 ppm during hypothermia. To evaluate brain injury and cerebral blood flow, magnetic resonance imaging was performed in wild-type mice after CA/CPR. Results:Hypothermia up-regulated the NOS3-dependent signaling in the brain (n = 6 to 7). Deficiency of NOS3 abolished the beneficial effects of hypothermia after CA/CPR (n = 5 to 6). Breathing nitric oxide at 40 ppm improved survival rate in hypothermia-treated NOS3−/− mice (n = 6) after CA/CPR compared with NOS3−/− mice that were treated with hypothermia alone (n = 6; P < 0.05). Breathing nitric oxide at 40 (n = 9) or 60 (n = 9) ppm markedly improved survival rates in TH-treated wild-type mice (n = 51) (both P < 0.05 vs. TH-treated wild-type mice). Inhaled nitric oxide during TH (n = 7) prevented brain injury compared with TH alone (n = 7) without affecting cerebral blood flow after CA/CPR (n = 6). Conclusions:NOS3 is required for the beneficial effects of TH. Inhaled nitric oxide during TH remains beneficial and further improves outcomes after CA/CPR. Nitric oxide breathing exerts protective effects after CA/CPR even when TH is ineffective due to impaired endogenous nitric oxide production.

Thiosulfate Mediates Cytoprotective Effects of Hydrogen Sulfide Against Neuronal Ischemia

Background Hydrogen 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 Results We 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. Conclusions The 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.

The mechanisms of the direct action of etomidate on vascular reactivity in rat mesenteric resistance arteries.

BACKGROUND: Etomidate minimally influences hemodynamics at a standard induction dose in young healthy patients, but can cause significant systemic hypotension at higher doses for induction or electroencephalographic burst suppression (i.e., cerebral protection) in patients with advanced age or heart disease, and during cardiopulmonary bypass. However, less is known about its action on systemic resistance arteries. METHODS: Using an isometric force recording method and fura-2-fluorometry, we investigated the action of etomidate on vascular reactivity in small mesenteric arteries from young (7–8 wk old, n = 179) and aged (96–98 wk old, n = 10) rats. RESULTS: In the endothelium-intact strips from young rats, etomidate enhanced the contractile response to norepinephrine or KCl (40 mM) at 3 &mgr;M but inhibited it at higher concentrations (≥10 &mgr;M). The enhancement was still observed after treatment with NG-nitro l-arginine, tetraethylammonium, diclofenac, nordihydroguaiaretic acid, losartan, ketanserin, BQ-123, or BQ-788, but was not observed in aged rats. In the endothelium-denuded strips from young rats, etomidate (≥10 &mgr;M) consistently inhibited the contractile response to norepinephrine or KCl without enhancement at 3 &mgr;M. In the fura-2-loaded, endothelium-denuded strips from young rats, etomidate inhibited norepinephrine- or KCl-induced increases in both intracellular Ca2+ concentration ([Ca2+]i) and force. Etomidate still inhibited the norepinephrine-induced increase in [Ca2+]i after depletion of the intracellular Ca2+ stores by ryanodine, which was sensitive to nifedipine. Etomidate had little effect on norepinephrine- or caffeine-induced Ca2+ release from the intracellular stores or Ca2+ uptake into the intracellular stores. During stimulation with norepinephrine or KCl, etomidate had little effect on the [Ca2+]i-force relation at low concentrations (≤30 &mgr;M) but caused its downward shift at 100 &mgr;M. CONCLUSIONS: In small mesenteric arteries, etomidate influences the contractile response to norepinephrine or membrane depolarization through endothelium-dependent enhancing and endothelium-independent inhibitory actions. The enhancement is at least in part independent of nitric oxide, endothelium-derived hyperpolarizing factor, cyclooxygenase products, lipoxygenase products, angiotensin II, serotonin, or endothelin-1, but may involve some signaling pathway that is impaired by aging. The endothelium-independent inhibition is due to decreases in both the [Ca2+]i and myofilament Ca2+ sensitivity in vascular smooth muscle cells. The decrease in [Ca2+]i would be due mainly to inhibition of voltage-gated Ca2+ influx. The observed inability of lower concentrations (1–3 &mgr;M) of etomidate to cause significant vasodilation is consistent with minimal changes in hemodynamics during induction of anesthesia with etomidate in young subjects, whereas the observed vasodilator action of higher concentrations of etomidate might underlie systemic hypotension caused by higher doses of etomidate in the clinical setting.

Farnesyltransferase inhibitor, tipifarnib, prevents galactosamine/lipopolysaccharide-induced acute liver failure.

ABSTRACT Acute liver failure (ALF) is a fatal syndrome associated with massive hepatocyte death. There is no cure for ALF except liver transplantation. Protein farnesylation is a lipid modification of cysteine residues that is catalyzed by farnesyltransferase (FTase) and has been proposed as an integral component of acute inflammation. Previously, we have demonstrated that FTase inhibitors improve survival in mouse models of endotoxemia and sepsis. Here we studied the effects of FTase inhibitor, tipifarnib, on galactosamine (GalN)/lipopolysaccharide (LPS)–induced ALF. The effects of tipifarnib (10 mg/kg, i.p.) were studied in GalN (400 mg/kg, i.p.)– and LPS (3 &mgr;g/kg)–challenged mice by histological and biochemical analyses. Galactosamine/LPS administration caused prominent liver injury characterized by the increased plasma alanine aminotransferase and aspartic aminotransferase levels, leading to significant mortality in mice. Tipifarnib inhibited GalN/LPS–induced caspase 3 activation, inflammatory cytokine production, and c-Jun N-terminal kinase phosphorylation in the liver. On the other hand, tipifarnib upregulated antiapoptotic protein, Bcl-xL, in the liver after GalN/LPS challenge. Tipifarnib also protected primary hepatocytes from GalN/tumor necrosis factor &agr;–induced cell death by inhibiting caspase 3 activation and upregulating antiapoptotic proteins. Galactosamine/LPS–induced liver injury was associated with increased protein farnesylation in the liver. Tipifarnib prevented protein farnesylation in the liver and markedly attenuated liver injury and mortality in GalN/LPS–challenged mice. These results suggest that protein farnesylation is a novel potential molecular target to prevent hepatocyte death and acute inflammatory liver failure in fulminant hepatitis.

Diabetes-associated Alterations in Volatile Anesthetic Actions on Contractile Response to Norepinephrine in Isolated Mesenteric Resistance Arteries

Background:Clinical concentrations of volatile anesthetics significantly influence contractile response to the sympathetic neurotransmitter norepinephrine although its precise mechanisms remain unclarified. In this study, we investigated its possible alterations in diabetes, as well as its underlying mechanisms. Methods:Isometric force was recorded in small mesenteric arteries from streptozotocin-induced diabetic and age-matched control rats. Results:The concentration–response curve for acetylcholine-induced endothelium-dependent relaxation was shifted to the right in diabetic arteries compared with controls. The concentration–response curve for norepinephrine-induced contraction was shifted to the left and upward by both endothelial denudation and diabetic induction. In the presence of endothelium, isoflurane or sevoflurane enhanced norepinephrine-induced contraction in control arteries but not in diabetic arteries; however, in its absence, both anesthetics identically inhibited norepinephrine-induced contraction in both groups. In control arteries, the isoflurane- or sevoflurane-induced enhancement was not affected by adrenomedullin22–52, calcitonin gene-related peptide8–37, 18&bgr;-glycyrrhetinic acid, NG-nitro l-arginine, ouabain, Ba2+, indomethacin, losartan, ketanserin, BQ-123, and BQ-788. Conclusions:In diabetes, vascular responses to acetylcholine, norepinephrine, and volatile anesthetics are altered in mesenteric resistance arteries, presumably reflecting endothelial dysfunction and possibly underlying circulatory instability during administration of either anesthetic. Some endothelial mechanisms that are impaired in diabetes would be involved in the anesthetic-induced enhancement of norepinephrine-induced contraction. However, the vasoregulatory mechanism mediated by adrenomedullin, calcitonin gene-related peptide, myoendothelial gap junction, nitric oxide, endothelium-derived hyperpolarizing factor, cyclooxygenase products, angiotensin II, serotonin, or endothelin-1, all of which have been suggested to be impaired in diabetes, would not be involved in the enhancement.

Esophageal Submucosal Hematoma Possibly Caused by Gastric Tube Insertion Under General Anesthesia

We present a case of an esophageal submucosal hematoma that developed after endovascular treatment for coil embolization for an unruptured cerebral aneurysm. The patient had received antiplatelet therapy before surgery and anticoagulation therapy during surgery. The orogastric tube was removed at case end with sustained negative pressure. After surgery, the patient reported chest and back pain and was diagnosed with an esophageal submucosal hematoma. The hematoma might have been related to the gastric tube insertion or removal. Providers should keep in mind the possibility of this complication when a patient who was given antithrombotic therapy reports chest or back pain after surgery.

Required time for setting up an anaesthesia machine mounted on a movable ceiling pendant

The present study was performed to evaluate the duration of time required to set up an anaesthesia machine mounted on an automated or manually movable ceiling pendant. Nurses moved the machine’s position according to the surgical site (right or left). The duration of time required to set up the anaesthesia machine for surgery was compared between automated and manual operation and among nurses with varying years of work experience. Movement of the anaesthesia machine from the right to left position took longer for the automated (278 ± 11s) than manual (188 ± 63s) method. However, no difference was observed between automated (288 ± 11s) and manual (267 ± 140s) movement of the machine from the left to right position. Experienced nurses took less time in both directions. Manual movement took less time than automated movement in the right-to-left direction, which may be advantageous when nurses are in a hurry or have musculoskeletal system disorders and may allow them to perform other operating room preparation tasks. Either automated or manual movement may be used depending on the situation. Both the larger deviations with manual movement and the shorter time required by experienced nurses suggest that training and experience shorten the manual set-up time.

The relationship between seizure in electroconvulsive therapy and pupillary response using an automated pupilometer

ObjectivesSeizure duration and morphology, postictal suppression, and sympathetic nervous system activation are all recommended as assessments of adequate seizure in electroconvulsive therapy (ECT). However, blood pressure and heart rate are not typically assessed as part of sympathetic nervous system activation because of the administration of anesthetic or cardiovascular agents during ECT. Although the pupils are known to reflect to the activity of autonomic nervous system and the degree of brain damage, previous studies have not examined the relationship between seizure of electroconvulsive therapy and pupillary response.MethodsWe conducted 98 sessions of ECT with 13 patients, divided into two groups according to seizure quality: (1) adequate or (2) inadequate. Pupillary light reflex [% constriction = (maximum resting pupil size {MAX} − minimum pupil size after light stimulation)/MAX × 100] was measured using a portable infrared quantitative pupilometer before anesthesia induction and immediately after electrical stimulation.ResultsThe number regarded as adequate was 67 times and as inadequate was 31 times. Maximum pupil size at the control and immediately after electrical stimulation was similar between the adequate and inadequate groups. Pupillary light reflex was similar at the control between both groups, but significantly smaller immediately after stimulation in the adequate group (2.5 ± 3.6%) compared with the inadequate group (10.6 ± 11.5%). Receiver operating characteristic curve analysis revealed that pupillary light reflex (> 5.5%) predicted adequate seizure.ConclusionsThe current findings suggest that pupillary constriction immediately after ECT could provide a helpful method for assessing the efficacy of ECT.

Effects of preoperative plasma exchange therapy with albumin replacement fluid on blood coagulation in patients undergoing ABO-incompatible living-donor kidney transplantation using rotational thromboelastometry

BackgroundABO-incompatible living-donor kidney transplantation (LDKT) requires immunotherapy and plasma exchange therapy (PEX). PEX with albumin replacement fluid reportedly decreases fibrinogen levels. However, no reports have described the effects of PEX with albumin replacement fluid on blood coagulation parameters and blood loss during the perioperative period. Therefore, we investigated the effects of preoperative PEX on blood coagulation parameters and blood loss during the perioperative period in patients undergoing ABO-incompatible LDKT as measured by rotational thromboelastometry (ROTEM®).MethodsTwenty-eight patients undergoing LDKT were divided into the PEX group (ABO incompatible with PEX, n = 13) and non-PEX group (ABO compatible without PEX, n = 15). ROTEM® parameters, standard laboratory test parameters, bleeding volume, and transfusion volume were compared between PEX and non-PEX group. MCEplatelet, which represents platelet contribution to clot strength and where “MCE” stands for maximum clot elasticity, was calculated from the difference in MCE between EXTEM and FIBTEM.ResultsThe bleeding volume during surgery and the intensive care unit (ICU) stay was significantly higher in the PEX than non-PEX group (p < 0.01). Maximum clot firmness (MCF) of EXTEM (MCFEXTEM), MCFFIBTEM, and MCEplatelet was significantly lower in the PEX than non-PEX group (p < 0.01). In the PEX group, the bleeding volume during surgery was very strongly correlated with the baseline MCFEXTEM and MCEplatelet, and the bleeding volume during the ICU stay was strongly correlated with the postoperative MCFEXTEM and MCEplatelet.ConclusionsThese results suggest that the increased blood loss in the PEX group during surgery and the ICU stay was associated with decreased platelet contribution to clot strength as measured by ROTEM®.Trial registrationUMIN-Clinical Trial Registry UMIN000018355. Registered 21 July 2015.