‘‘Beet-ing’’ the Mountain: A Review of the Physiological and Performance Effects of Dietary Nitrate Supplementation at Simulated and Terrestrial Altitude

Exposure to altitude results in multiple physiological consequences. These include, but are not limited to, a reduced maximal oxygen consumption, drop in arterial oxygen saturation, and increase in muscle metabolic perturbations at a fixed sub-maximal work rate. Exercise capacity during fixed work rate or incremental exercise and time-trial performance are also impaired at altitude relative to sea-level. Recently, dietary nitrate (NO3-) supplementation has attracted considerable interest as a nutritional aid during altitude exposure. In this review, we summarise and critically evaluate the physiological and performance effects of dietary NO3- supplementation during exposure to simulated and terrestrial altitude. Previous investigations at simulated altitude indicate that NO3- supplementation may reduce the oxygen cost of exercise, elevate arterial and tissue oxygen saturation, improve muscle metabolic function, and enhance exercise capacity/ performance. Conversely, current evidence suggests that NO3- supplementation does not augment the training response at simulated altitude. Few studies have evaluated the effects of NO3- at terrestrial altitude. Current evidence indicates potential improvements in endothelial function at terrestrial altitude following NO3- supplementation. No effects of NO3- supplementation have been observed on oxygen consumption or arterial oxygen saturation at terrestrial altitude, although further research is warranted. Limitations of the present body of literature are discussed, and directions for future research are provided

Endogenous S-nitrosothiols protect against myocardial injury

Despite substantial evidence that nitric oxide (NO) and/or endogenous S-nitrosothiols (SNOs) exert protective effects in a variety of cardiovascular diseases, the molecular details are largely unknown. Here we show that following left coronary artery ligation, mice with a targeted deletion of the S-nitrosoglutathione reductase gene (GSNOR−/−) have reduced myocardial infarct size, preserved ventricular systolic and diastolic function, and maintained tissue oxygenation. These profound physiological effects are associated with increases in myocardial capillary density and S-nitrosylation of the transcription factor hypoxia inducible factor-1α (HIF-1α) under normoxic conditions. We further show that S-nitrosylated HIF-1α binds to the vascular endothelial growth factor (VEGF) gene, thus identifying a role for GSNO in angiogenesis and myocardial protection. These results suggest innovative approaches to modulate angiogenesis and preserve cardiac function

Congenital H-type tracheoesophageal fistula: A multicenter review of outcomes in a rare disease

© 2017 Elsevier Inc. Objective To perform a multicenter review of outcomes in patients with H-type tracheoesophageal fistula (TEF) in order to better understand the incidence and causes of post-operative complications. Background H-type TEF without esophageal atresia (EA) is a rare anomaly with a fundamentally different management algorithm than the more common types of EA/TEF. Outcomes after surgical treatment of H-type TEF are largely unknown, but many authoritative textbooks describe a high incidence of respiratory complications. Methods A multicenter retrospective review of all H-type TEF patients treated at 14 tertiary children\u27s hospital from 2002–2012 was performed. Data were systematically collected concerning associated anomalies, operative techniques, hospital course, and short and long-term outcomes. Descriptive analyses were performed. Results We identified 102 patients (median 9.5 per center, range 1–16) with H-type TEF. The overall survival was 97%. Most patients were repaired via the cervical approach (96%). The in-hospital complication rate, excluding vocal cord issues, was 16%; this included an 8% post-operative leak rate. Twenty-two percent failed initial extubation after repair. A total of 22% of the entire group had vocal cord abnormalities (paralysis or paresis) on laryngoscopy that were likely because of recurrent laryngeal nerve injury. Nine percent required a tracheostomy. Only 3% had a recurrent fistula, all of which were treated with reoperation. Conclusions There is a high rate of recurrent laryngeal nerve injury after H-type TEF repair. This underscores the need for meticulous surgical technique at the initial repair and suggests that early vocal cord evaluation should be performed for any post-operative respiratory difficulty. Routine evaluation of vocal cord function after H-type TEF repair should be considered. The level of evidence rating Level IV