Estimation of the Number of General Anesthesia Cases Based on a Series of Nationwide Surveys on Twitter during COVID-19 Pandemic in Japan: A Statistical Analysis.

Background and objectives: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread to more than 200 countries. In light of this situation, the Japanese Government declared a state of emergency in seven regions of Japan on 7 April 2020 under the provisions of the law. The medical care delivery system has been under pressure. Although various surgical societies have published guidelines on which to base their surgical decisions, it is not clear how general anesthesia has been performed and will be performed in Japan. Materials and Methods: One of the services provided by the social network service Twitter is a voting function-Twitter Polls-through which anonymous surveys were conducted. We analyzed the results of a series of surveys 17 times over 22 weeks on Twitter on the status of operating restrictions using quadratic programming to solve the mathematical optimizing problem, and public data provided by the Japanese Government were used to estimate the current changes in the number of general anesthesia performed in Japan. Results: The minimum number of general anesthesia cases per week was estimated at 67.1% compared to 2015 on 27 April 2020. The timeseries trend was compatible with the results reported by the Japanese Society of Anesthesiologists (correlation coefficient r = 0.69, p < 0.001). Conclusions: The number of general anesthesia was reduced up to two-thirds during the pandemic of COVID-19 in Japan and was successfully quantitatively estimated using a quick questionnaire on Twitter.

Effect of propofol on androgen receptor activity in prostate cancer cells.

Androgen receptor is a nuclear receptor and transcription factor activated by androgenic hormones. Androgen receptor activity plays a pivotal role in the development and progression of prostate cancer. Although accumulating evidence suggests that general anesthetics, including opioids, affect cancer cell growth and impact patient prognosis, the effect of those drugs on androgen receptor in prostate cancer is not clear. The purpose of this study was to investigate the effect of the general anesthetic propofol on androgen receptor activity in prostate cancer cells. An androgen-dependent human prostate cancer cell line (LNCaP) was stimulated with dihydrotestosterone (DHT) and exposed to propofol. The induction of androgen receptor target genes was investigated using real-time reverse transcription polymerase chain reaction, and androgen receptor protein levels and localization patterns were analyzed using immunoblotting and immunofluorescence assays. The effect of propofol on the proliferation of LNCaP cells was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Propofol significantly inhibited DHT-induced expression of androgen receptor target genes in a dose- and time-dependent manner, and immunoblotting and immunofluorescence assays indicated that propofol suppressed nuclear levels of androgen receptor proteins. Exposure to propofol for 24h suppressed the proliferation of LNCaP cells, whereas 4h of exposure did not exert significant effects. Together, our results indicate that propofol suppresses nuclear androgen receptor protein levels, and inhibits androgen receptor transcriptional activity and proliferation in LNCaP cells.

Use of extracorporeal membrane oxygenation in complicated transcatheter aortic valve replacement.

OBJECTIVES: Although transcatheter aortic valve replacement (TAVR) is an excellent alternative procedure for high-risk patients with severe symptomatic aortic stenosis, it is often associated with life-threatening complications. We report on the emergency or elective use of veno-arterial extracorporeal membrane oxygenation (ECMO) to manage these complications. METHODS: Between December 2013 and February 2016, 46 patients underwent TAVR at our institution. Of these, 4 patients required emergency ECMO support and another 3 patients were electively placed on ECMO support at the start of the procedure. The mean age of the ECMO patients was 87.3 ± 3.6 years and all were female. The Society of Thoracic Surgeons-predicted risk of mortality score in these patients was 12.2 ± 6.2%. RESULTS: TAVR with ECMO was completed through the transapical approach in 6 patients, and the transfemoral approach in 1 patient. The arterial access route for ECMO was the femoral artery in 5, the external iliac artery in 1, and the subclavian artery in 1. Indications for the use of emergency ECMO were hemodynamic instability in 2, cardiogenic shock in 2, while indications for elective ECMO were severe pulmonary hypertension, impaired left ventricular function and a combination of these. There was no 30-day mortality, and the 1-year survival rate was 83.3% with no significant difference compared to patients without ECMO support. CONCLUSION: The use of ECMO in very high-risk patients undergoing TAVR may increase safety and contribute to excellent outcomes. Although ECMO support is rarely needed in TAVR, a well-prepared treatment strategy by the heart team is mandatory.

Cigarette smoke reversibly activates hypoxia-inducible factor 1 in a reactive oxygen species-dependent manner.

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.

[Extracorporeal Membrane Oxygenation for Anesthesia Induction in a Patient with Severe Cardiorespiratory Impairment due to Mediastinal Angiosarcoma].

BACKGROUND: Mediastinal angiosarcoma is a rare intrathoracic tumor that can cause severe pleural and pericardial fibrosis. CASE REPORT: We report the anesthetic management for pericardiectomy and pleurolysis in a 33-year-old patient with a mediastinal angiosarcoma. He presented with severe restrictive ventilatory impairment and heart failure due to fibrosis of the pleura and pericardium. Spirometry indicated a forced vital capacity of 0.66 l, while arterial blood gas analysis under noninvasive positive pressure ventilation indicated hypercapnia (pH 7.44; Pa(CO2) 59.2 mmHg). His cardiac index was 1.36 l x min(-1) x m(-2). Anesthesia induction and positive pressure ventilation are associated with an extremely high cardiorespiratory risk; therefore, veno-arterial-extracorporeal membrane oxygenation (VA-ECMO) with femoral cannulation was started prior to anesthesia induction. After achieving a stable circulation and adequate gas exchange, anesthesia was induced, and mechanical ventilation with intratracheal intubation was initiated. With ECMO and inotropic support stable hemodynamics was maintained throughout anesthesia induction and the operation was performed uneventfully under cardiopulmonary bypass. The patient was extubated on the first postoperative day and discharged one month after the operation. CONCLUSION: ECMO is a useful option to secure adequate gas exchange and circulation during anesthesia induction in patients with severe cardiopulmonary problems due to mediastinal tumors.

Midazolam inhibits the hypoxia-induced up-regulation of erythropoietin in the central nervous system.

Erythropoietin (EPO), a regulator of red blood cell production, is endogenously expressed in the central nervous system. It is mainly produced by astrocytes under hypoxic conditions and has proven to have neuroprotective and neurotrophic effects. In the present study, we investigated the effect of midazolam on EPO expression in primary cultured astrocytes and the mouse brain. Midazolam was administered to 6-week-old BALB/c male mice under hypoxic conditions and pregnant C57BL/6N mice under normoxic conditions. Primary cultured astrocytes were also treated with midazolam under hypoxic conditions. The expression of EPO mRNA in mice brains and cultured astrocytes was studied. In addition, the expression of hypoxia-inducible factor (HIF), known as the main regulator of EPO, was evaluated. Midazolam significantly reduced the hypoxia-induced up-regulation of EPO in BALB/c mice brains and primary cultured astrocytes and suppressed EPO expression in the fetal brain. Midazolam did not affect the total amount of HIF proteins but significantly inhibited the nuclear expression of HIF-1α and HIF-2α proteins. These results demonstrated the suppressive effects of midazolam on the hypoxia-induced up-regulation of EPO both in vivo and in vitro.

Preoperative Hypercapnia as a Predictor of Hypotension During Anesthetic Induction in Lung Transplant Recipients.

OBJECTIVE: To determine the incidence and predisposing factors of hypotension during anesthetic induction in lung transplant recipients. DESIGN: Retrospective study. SETTING: University hospital. PARTICIPANTS: Patients who underwent lung transplantation between 2008 and 2013 (n = 68). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The authors analyzed the mean arterial pressure (MAP) from administration of anesthetic drugs to 10 minutes after endotracheal intubation (ie, the anesthetic induction) among participants who underwent lung transplantation. Patients were considered to have clinically significant hypotension (CSH) when the following criteria were fulfilled: An MAP decrease of>40% from baseline and MAP of<60 mmHg. Overall, 41.2% of patients experienced CSH during the induction of anesthesia. The preoperative partial pressure of carbon dioxide (PaCO2) was significantly higher in patients who experienced CSH during anesthetic induction than in those who did not (p = 0.005). Preoperative PaCO2 predicted the development of CSH during anesthetic induction (area under the curve = 0.702; p = 0.002), with an optimal cut-off point of 55 mmHg determined by maximizing the Youden index. The incidences of CSH during anesthetic induction for patients with (PaCO2 ≥ 55) and without (PaCO2<55) preoperative hypercapnia were 75.0% (95% confidence interval [CI] [53.8-89.2]) and 30.8% (95% CI 26.4-37.3), respectively. After adjustment for known predicting factors, the odds ratio for the relationship between preoperative hypercapnia and CSH during anesthetic induction was 12.54 (95% CI 3.10-66.66). CONCLUSIONS: Hypotension during anesthetic induction is common in lung transplant recipients, and is independently predicted by preoperative hypercapnia.

The clinical course of anesthetic induction in lung transplant recipients with pulmonary complications after hematopoietic stem cell transplantation.

PURPOSE: We examined the clinical course of anesthetic induction in lung transplant recipients with pulmonary complications after hematopoietic stem cell transplantation (post-HSCT), focusing on ventilatory management. We aimed to determine the incidence of oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction in post-HSCT lung transplant recipients, and to explore factors associated with their development. METHODS: Nineteen consecutive patients who underwent lung transplantation post-HSCT at Kyoto University Hospital (Japan) were retrospectively studied. Data regarding patient characteristics, preoperative examination, and clinical course during anesthetic induction were analyzed. RESULTS: The incidence of oxygen desaturation (SpO2 < 90 %) during anesthetic induction and severe respiratory acidosis (pH < 7.2) after anesthetic induction were 21.1 and 26.3 %, respectively. Reduced dynamic compliance (Cdyn) during mechanical ventilation was significantly associated with oxygen desaturation during anesthetic induction (p = 0.01), as well as severe respiratory acidosis after anesthetic induction (p = 0.01). The preoperative partial pressure of carbon dioxide in arterial blood (PaCO2; r = -0.743, p = 0.002) and body mass index (BMI; r = 0.61, p = 0.021) significantly correlated with Cdyn, and multivariate analysis revealed that both PaCO2 and BMI were independently associated with Cdyn. CONCLUSIONS: Oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction frequently occur in post-HSCT lung transplant recipients. Low Cdyn may, at least partially, explain oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction. Moreover, preoperative hypercapnia and low BMI were predictive of low Cdyn.

Successful surgical aortic valve replacement for prosthetic valve infective endocarditis following transcatheter aortic valve implantation.

An 80-year-old male underwent a transcatheter aortic valve implantation (TAVI) for severe senile aortic stenosis. Six weeks after the surgery, he was readmitted to our institution because of a high-grade fever. Transesophageal echocardiography revealed thickening of all three leaflets of the aortic prosthesis and mobile mass on the leaflet, and Streptococcus sanguis was identified from his blood culture. Therefore, he was diagnosed with prosthetic valve endocarditis (PVE) and received intensive intravenous antibiotic therapy. Because he did not respond to the pharmacological therapy, surgical aortic valve replacement (AVR) was indicated although it was considered a relatively high-risk procedure. Herein, we report on the successful surgical AVR in this patient using a pericardial valve after removal of the infected prosthetic valve, and discuss some issues related to this rare complication after TAVI. .

Successful balloon aortic valvuloplasty as a bridge therapy to transcatheter aortic valve implantation during the proctoring period.

In Japan, transcatheter aortic valve implantation (TAVI) with Edwards-SAPIEN XT valve (Edwards Lifesciences Inc., Irvine, CA, USA) started in October 2013. All institutions should undergo a training period to perform TAVI independently. Balloon aortic valvuloplasty (BAV) as a bridge to TAVI during the training period should be performed with caution to avoid severe aortic regurgitation (AR) because bailout TAVI is not possible. We present a case in which BAV was successfully performed as a bridge to TAVI during the training period. The patient was an 85-year-old man with medically uncontrollable congestive heart failure due to severe aortic valve stenosis. The aortic valve area was 0.60 cm2 with a left ventricular ejection fraction of 20%. TAVI was considered a safe but high-risk strategy owing to the unstable hemodynamic condition. We chose BAV as a bridge therapy to TAVI. The aortic annulus diameter was 25.3 mm on computed tomography scans. We chose a 20-mm balloon catheter to avoid BAV-induced AR. Transfemoral TAVI was performed successfully 16 days after BAV using a 26-mm SAPIEN XT valve. The postoperative course was uneventful. The case demonstrated BAV as a bridge therapy to TAVI can be safely and effectively performed during the training period. .

[Evaluation of postoperative pain intensity after ear, nose, and throat surgery--the effect of intraoperative fentanyl use].

BACKGROUND: This study was designed to determine postoperative pain levels after ear, nose, and throat (ENT) surgery, and also to examine whether intraoperative fentanyl use during ENT surgery enhances the quality of postoperative pain control. METHODS: The distribution of pain scores and rescue analgesic requirements among 198 patients undergoing ENT surgery were examined. Multivariate logistic regression analysis was performed to identify independent factors associated with moderate to severe postoperative pain (maximal pain score ≥ 5 on the numerical rating scale) and postoperative nausea and vomiting (PONV). RESULTS: 27.8% of patients experienced moderate to severe postoperative pain after ENT surgery. The distribution of postoperative pain levels was similar among procedures performed on different anatomical regions. Intraoperative fentanyl use was not associated with moderate to severe postoperative pain (adjusted odds ratio (95% confidence interval) :1.03 (0.51-2.13))]. On the other hand, intraoperative fentanyl use was independently associated with PONV [3.10 (1.25-8.92); P = 0.0138]. CONCLUSIONS: Prevalence of moderate to severe postoperative pain after ENT surgery was approximately 28%. Intraoperative fentanyl use was not associated with a decreased incidence of moderate to severe postoperative pain, but was significantly associated with PONV.

Orthostatic intolerance during early mobilization following video-assisted thoracic surgery.

PURPOSE: Early postoperative mobilization is crucial for early ambulation to reduce postoperative pulmonary complications after lung resection. However, orthostatic intolerance (OI) may delay patient recovery, leading to complications. It is therefore important to understand the prevalence of and predisposing factors for OI following video-assisted thoracic surgery (VATS), which have not been established. This study evaluated the incidence of OI, impact of OI on delayed ambulation, and predisposing factors associated with OI in patients after VATS. METHODS: This retrospective cohort study consecutively analyzed data from 236 patients who underwent VATS. The primary outcome was defined as OI with symptoms associated with ambulatory challenge on postoperative day 1 (POD1), including dizziness, nausea and vomiting, feeling hot, blurred vision, or transient syncope. Multivariate logistic regression was performed to identify independent factors associated with OI. RESULTS: Of the 236 patients, 35.2 % (83) experienced OI; 45.8 % of these could not ambulate at POD1, compared with 15.7 % of patients without OI (P < 0.001). Factors independently associated with OI included advanced age [odds ratio 2.83 (1.46-5.58); P = 0.002], female gender [odds ratio 2.40 (1.31-4.46); P = 0.004], and postoperative opioid use [odds ratio 2.61 (1.23-5.77); P = 0.012]. Use of thoracic epidural anesthesia was not independently associated with OI [odds ratio 0.72 (0.38-1.37); P = 0.318]. CONCLUSION: Postoperative OI was common in patients after VATS and significantly associated with delayed ambulation. Advanced age, female gender, and postoperative opioid use were identified as independent predisposing factors for OI.

Hydrogen sulfide inhibits hypoxia- but not anoxia-induced hypoxia-inducible factor 1 activation in a von hippel-lindau- and mitochondria-dependent manner.

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 hypoxia-inducible 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-1α 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-α 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-1α protein but destabilized HIF-1α 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 mitochondria-dependent manner.

Fentanyl activates hypoxia-inducible factor 1 in neuronal SH-SY5Y cells and mice under non-hypoxic conditions in a µ-opioid receptor-dependent manner.

Hypoxia-inducible factor 1 (HIF-1) is the main transcription factor responsible for hypoxia-induced gene expression. Perioperative drugs including anesthetics have been reported to affect HIF-1 activity. However, the effect of fentanyl on HIF-1 activity is not well documented. In this study, we investigated the effect of fentanyl and other opioids on HIF-1 activity in human SH-SY5Y neuroblastoma cells, hepatoma Hep3B cells, lung adenocarcinoma A549 cells and mice. Cells were exposed to fentanyl, and HIF-1 protein expression was examined by Western blot analysis using anti-HIF-1α and ß antibodies. HIF-1-dependent gene expression was investigated by semi-quantitative real-time reverse transcriptase (RT)-PCR (qRT-PCR) and luciferase assay. Furthermore, fentanyl was administered intraperitoneally and HIF-1-dependent gene expression was investigated by qRT-PCR in the brains and kidneys of mice. A 10-µM concentration of fentanyl and other opioids, including 1 µM morphine and 4 µM remifentanil, induced HIF-1α protein expression and HIF-1 target gene expression in an opioid receptor-dependent manner in SH-SY5Y cells with activity peaking at 24h. Fentanyl did not augment HIF-1α expression during hypoxia-induced induction. HIF-1α stabilization assays and experiments with cycloheximide revealed that fentanyl increased translation from HIF-1α mRNA but did not stabilize the HIF-1α protein. Furthermore, fentanyl induced HIF-1 target gene expression in the brains of mice but not in their kidneys in a naloxone-sensitive manner. In this report, we describe for the first time that fentanyl, both in vitro and in vivo, induces HIF-1 activation under non-hypoxic conditions, leading to increases in expression of genes associated with adaptation to hypoxia.

General anesthetics inhibit erythropoietin induction under hypoxic conditions in the mouse brain.

BACKGROUND: Erythropoietin (EPO), originally identified as a hematopoietic growth factor produced in the kidney and fetal liver, is also endogenously expressed in the central nervous system (CNS). EPO in the CNS, mainly produced in astrocytes, is induced under hypoxic conditions in a hypoxia-inducible factor (HIF)-dependent manner and plays a dominant role in neuroprotection and neurogenesis. We investigated the effect of general anesthetics on EPO expression in the mouse brain and primary cultured astrocytes. METHODOLOGY/PRINCIPAL FINDINGS: BALB/c mice were exposed to 10% oxygen with isoflurane at various concentrations (0.10-1.0%). Expression of EPO mRNA in the brain was studied, and the effects of sevoflurane, halothane, nitrous oxide, pentobarbital, ketamine, and propofol were investigated. In addition, expression of HIF-2α protein was studied by immunoblotting. Hypoxia-induced EPO mRNA expression in the brain was significantly suppressed by isoflurane in a concentration-dependent manner. A similar effect was confirmed for all other general anesthetics. Hypoxia-inducible expression of HIF-2α protein was also significantly suppressed with isoflurane. In the experiments using primary cultured astrocytes, isoflurane, pentobarbital, and ketamine suppressed hypoxia-inducible expression of HIF-2α protein and EPO mRNA. CONCLUSIONS/SIGNIFICANCE: Taken together, our results indicate that general anesthetics suppress activation of HIF-2 and inhibit hypoxia-induced EPO upregulation in the mouse brain through a direct effect on astrocytes.

Anesthesia management for emergency laparotomy in a pediatric patient with suspected hereditary angioedema.

Hereditary angioedema (HAE) is caused by complement factor 1 inhibitor (C1-INH) deficiency, and its mode of inheritance is autosomal dominant. We present a case of an 8-year-old patient who required emergency laparotomy after a traffic accident. General anesthesia with tracheal intubation was necessary. The patient's mother and maternal grandmother had been diagnosed with HAE. HAE is associated with high mortality when airway edema is caused by tracheal intubation. It was impossible to rule out HAE preoperatively in the patient. Therefore, we presumed that he had HAE and treated him with pasteurized C1-INH concentrate. The patient underwent laparotomy uneventfully. Several days after the operation, the laboratory data revealed that the perioperative plasma complement 1 q subunit (C1q) protein level and C1-INH function were not lowered. The diagnosis of HAE was not confirmed, but it was not possible to rule out the diagnosis either. The prophylactic use of a C1-INH in this case may be justified, because the procedure was an emergency and because of the high mortality associated with tracheal intubation in patients with HAE.

Persisting mild hypothermia suppresses hypoxia-inducible factor-1alpha protein synthesis and hypoxia-inducible factor-1-mediated gene expression.

The transcription factor hypoxia-inducible factor-1 (HIF-1) plays an essential role in regulating gene expression in response to hypoxia-ischemia. Ischemia causes the tissue not only to be hypoxic but also to be hypothermic because of the hypoperfusion under certain circumstances. On the other hand, the induced hypothermia is one of the most common therapeutic modalities to extend tolerance to hypoxia. Although hypoxia elicits a variety of cellular and systemic responses at different organizational levels in the body, little is known about how hypoxia-induced responses are affected by low temperature. We examined the influence of mild hypothermic conditions (28-32 degrees C) on HIF-1 in both in vitro and in vivo settings. In vitro experiments adopting cultured cells elucidated that hypoxia-induced HIF-1 activation was resistant to 4-h exposure to the low temperature. In contrast, exposure to the low temperature as long as 24 h suppressed HIF-1 activation and the subsequent upregulation of HIF-1 target genes such as VEGF or GLUT-1. HIF-1alpha protein stability in the cell was not affected by hypothermic treatment. Furthermore, intracellular ATP content was reduced under 1% O(2) conditions but was not largely affected by hypothermic treatment. The evidence indicates that reduction of oxygen consumption is not largely involved in suppression of HIF-1. In addition, we demonstrated that HIF-1 DNA-binding activity and HIF-1-dependent gene expressions induced under 10% O(2) atmosphere in mouse brain were not influenced by treatment under 3-h hypothermic temperature but were inhibited under 5-h treatment. On the other hand, we indicated that warming ischemic legs of mice for 24 h preserved HIF-1 activity. In this report we describe for the first time that persisting low temperature significantly reduced HIF-1alpha neosynthesis under hypoxic conditions, leading to a decrease in gene expression for adaptation to hypoxia in both in vitro and in vivo settings.