Intermittent Hypoxia

Intermittent hypoxia can cause significant structural and functional impact on the systemic, organic, cellular and molecular processes of human physiology and pathophysiology. This book focuses on the most updated scientific understanding of the adaptive (beneficial) and maladaptive (detrimental) responses to intermittent hypoxia and their potential pathogenetic or prophylactic roles in the development and progression of major human diseases. This is a comprehensive monograph for clinicians, research scientists, academic faculty, postgraduate and medical students, and allied health professionals who are interested in enhancing their up-to-date knowledge of intermittent hypoxia research and its translational applications in preventing and treating major human diseases.

Recently, endurance athletes and high altitude climbers have gained access to commercially available, portable normobaric hypoxic chambers. Intermittent exposures to hypoxia in these chambers may elicit adaptations similar to those observed during acclimatization to altitude. Manufactures of these systems purport that intermittent exposures may elicit adaptations similar to those observed in response to the hypoxia of high altitude, however there have been no reports in the scientific literature that ventilatory acclimatization or alterations in cerebrovascular dynamics occur following repeated episodes in the portable chambers. The main conclusions are that an intermittent normobaric hypoxic intervention, consisting of five consecutive overnight exposures to a simulated altitude of 4300m, elicits perturbations in the acute cerebrovascular and ventilatory responses to both hypoxia and hypercapnia, which are similar to changes following chronic altitude exposure. Individual variability to intermittent hypoxia may have an impact on the rate at which the process of acclimatization proceeds. The extent of physiological and symptomatic responses to intermittent hypoxia are likely to be associated with the severity of hypoxia as well as the length and number of recurrent episodes of hypoxia.

Hypoxia remains a constant threat throughout life. It is for this reason that the International Hypoxia Society strives to maintain a near quarter century tradition of presenting a stimulating blend of clinical and basic science discussions. International experts from many fields have focused on the state-of-the-art discoveries in normal and pathophysiological responses to hypoxia. Topics in this volume include gene-environment interactions, a theme developed in both a clinical context regarding exercise and hypoxia, as well as in native populations living in high altitudes. Furthermore, experts in the field have combined topics such as skeletal muscle angiogenesis and hypoxia, high altitude pulmonary edema, new insights into the biology of the erythropoietin receptor, and the latest advances in cardiorespiratory control in hypoxia. This volume explores the fields of anatomy, cardiology, biological transport, and biomedical engineering among many others.

In consolidation of the most updated experimental results and perspectives from diverse research fields on a main theme - intermittent hypoxia, this book encompasses the structural, physiological, pathophysiological, biochemical, genetic, metabolic, and therapeutic aspects of intermittent hypoxia.

Evidence Based Pediatrics and Child Health is a ground-breaking new text on pediatrics and child care management, using evidence based approach. It covers all the major childhood conditions and contains the features of both a handbook and a reference text. Each chapter combines both advice on management and how best to practice evidence based medicine with reviews of all the available evidence in a specific area. The goal of the book is to help pediatricians and others who care for children to provide the best possible care by combining the best, most current evidence with special circumstances of each individual patient.

With high morbidity and mortality rates, atherosclerosis (ATS) is a major concern worldwide. This book provides comprehensive information on ATS, including chapters on cardiovascular disease and obstructive sleep apnea, rheumatology and cardiovascular risk, and the differences of ATS among men and women. Let’s hope for the best and thank you to all my team for collaborating in this book production. In particular, thanks • to Bruno (my expert colleague) and Aurel (my secretary) for analyzing and reading with me all the texts • to Vincenzo, Stefano and Andrea for English evaluation • and finally to Rebecca (my future wife) for sustaining me in all professional activities giving me power in daily life!

The appearance of photosynthetic organisms about 3 billion years ago increased the partial pressure of oxygen (PO2) in the atmosphere and enabled the evolution of organisms that use glucose and oxygen to produce ATP by oxidative phosphorylation. Hypoxia is commonly defined as the reduced availability of oxygen in the tissues produced by different causes, which include reduction of atmospheric PO2 as in high altitude, and secondary to pathological conditions such as sleep breathing and pulmonary disorders, anemia, and cardiovascular alterations leading to inadequate transport, delivery, and exchange of oxygen between capillaries and cells. Nowadays, it has been shown that hypoxia plays an important role in the genesis of several human pathologies including cardiovascular, renal, myocardial and cerebral diseases in fetal, young and adult life. Several mechanisms have evolved to maintain oxygen homeostasis. Certainly, all cells respond and adapt to hypoxia, but only a few of them can detect hypoxia and initiate a cascade of signals intended to produce a functional systemic response. In mammals, oxygen detection mechanisms have been extensively studied in erythropoietin-producing cells, chromaffin cells, bulbar and cortical neurons, pulmonary neuroepithelial cells, smooth muscle cells of pulmonary arteries, and chemoreceptor cells. While the precise mechanism underpinning oxygen, sensing is not completely known several molecular entities have been proposed as possible oxygen sensors (i.e. Hem proteins, ion channels, NADPH oxidase, mitochondrial cytochrome oxidase). Remarkably, cellular adaptation to hypoxia is mediated by the master oxygen-sensitive transcription factor, hypoxia-inducible factor-1, which can induce up-regulation of different genes to cope the cellular effects related to a decrease in oxygen levels. Short-term responses to hypoxia included mainly chemoreceptor-mediated reflex ventilatory and hemodynamic adaptations to manage the low oxygen concentration while more prolonged exposures to hypoxia can elicit more sustained physiological responses including switch from aerobic to anaerobic metabolism, vascularization, and enhancement of blood O2 carrying capacity. The focus of this research topic is to provide an up-to-date vision on the current knowledge on oxygen sensing mechanism, physiological responses to acute or chronic hypoxia and cellular/tissue/organ adaptations to hypoxic environment.