A simulation study to compare physiological responses to hypoxia and exercise between anaemic subjects and healthy controls

Objectives: Military flying is a complex task and requires high level of physical fitness of aviators. Various aviation stressors such as acceleratory force, hypoxia, cold weather conditions and decompression sickness place enormous stress on human physiological systems of the aviators. Individuals with Hb <13 g/dL (males) are being placed in the lower medical category which makes them unfit to fly. The present study was undertaken to assess the implication of low haemoglobin (Hb) on exercise capacity and hypoxia tolerance. Materials and Methods: Twenty-five individuals with anaemia and 15 healthy controls participated in the study. The participants were subjected to normobaric hypoxia (NH) equivalent to an altitude of 15,000 feet. Different physiological parameters such as heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), respiratory rate (fR) and arterial oxygen saturation (SpO2) were measured during NH. Participants also performed maximal aerobic capacity (V?O2 max) and maximal anaerobic capacity test in bicycle ergometer. Results: HR, SBP, DBP and fR in anaemic subjects were higher than healthy controls during NH, whereas SpO2 in anaemic subjects was lower as compared to healthy controls. Anaemic individuals had a lower VO2 max than their healthy counterparts. Critical power and anaerobic work capacity were lower in anaemic subjects than healthy controls. Conclusion: There is a deterioration in exercise capacity and hypoxia tolerance in individuals with low Hb levels. Adequate precaution should be exercised for permitting military aviators to fly with low Hb level.

Application prospects of naked mole rats in biomedical research / 中国实验动物学报

Naked mole rats are unique animals with long lifetime, anti-tumor properties, hypoxia tolerance, low metabolic rate, analgesia, tactile sensitiveness, poor eyesight and strong bone regeneration ability. Based on the basic bio-logical characteristics of naked mole rats, and the current research trends in the field of cancer, aging, hypoxia tolerance, as well as algesia, this review focuses on the application prospects of naked mole rats in biomedical research.

Gill dimensions in near-term embryos of Amazonian freshwater stingrays (Elasmobranchii: Potamotrygonidae) and their relationship to the lifestyle and habitat of neonatal pups

This comparative study of gill morphometrics in near-term embryos of freshwater stingray potamotrygonids examines gill dimensions in relation to neonatal lifestyle and habitat. In embryos of the potamotrygonids Paratrygon aiereba, Plesiotrygon iwamae, Potamotrygon motoro, Potamotrygon orbignyi, and cururu ray Potamotrygon sp. the number and length of filaments, total gill surface area, mass-specific surface area, water-blood diffusion distance, and anatomical diffusion factor were analysed. In all potamotrygonids, the 3rd branchial arch possessed a larger respiratory surface than the other gill arches. Larger embryos had more gill surface area and large spiracles, which are necessary to maintain the high oxygen uptake needed due to their larger body size. However, the higher mass-specific gill surface area observed in near-term embryos may be advantageous because neonates can use hypoxic environments as refuges against predators, as well as catch small prey that inhabit the same environment. As expected from their benthic mode of life, freshwater stingrays are sluggish animals compared to pelagic fishes. However, based on gill respiratory morphometry (such as gill area, mass-specific gill area, the water-blood diffusion barrier, anatomical diffusion factor, and relative opening of the spiracle), subtypes of lifestyles can be observed corresponding to: active, intermediate, and sluggish species according to Gray's scale.

Este estudo realizado com embriões a termo de arraias de água doce (Potamotrygonidae) compara e analisa as dimensões branquiais em relação ao estilo de vida e habitat dos neonatos. Nos embriões de Paratrygon aiereba, Plesiotrygon iwamae, Potamotrygon motoro, Potamotrygon orbignyi e Potamotrygon sp. (arraia cururu) foram analisados número e comprimento dos filamentos, área branquial, área superficial branquial massa-específica, barreira de difusão água-sangue e fator de difusão anatômico. Em todos os potamotrigonídeos estudados, o 3º arco branquial possui uma superfície respiratória maior que os demais arcos. Embriões de espécies de maior porte possuem grandes espiráculos e maior área de superfície branquial. Isso ajuda a manter a taxa de absorção de oxigênio proporcional ao requerimento do animal. No entanto, a grande área de superfície branquial massa-específica observadas nos embriões a termo pode ser vantajosa, pois os neonatos podem usar ambientes hipóxicos como refúgios contra predadores, bem como capturar pequenas presas que habitam o mesmo ambiente. Devido ao modo de vida bentônico, as arraias de água doce são nadadoras lentas comparadas aos peixes pelágicos. No entanto, com base na morfometria branquial (área de superfície branquial, área branquial massa-específica, barreira de difusão água-sangue, fator de difusão anatômico e abertura relativa do espiráculo), subtipos de estilos de vida podem ser observados: ativas, intermediárias e lentas, conforme escala definida por Gray.

Influence of Repeated Exposures to Hypobaric Chamber on Acute Hypoxia Tolerance / 항공우주의학회지

BACKGROUND: Acute hypoxia tolerance has been evaluated by the time of useful consciousness, subjective symptoms, cardiovascular changes, visual deterioration, psychological performance, and so forth. But these methods are either subjective, lacking strict objectivity, or too demanding to collect sufficient data. Pulse oximeter monitoring has come to be used not only in hospitals but in the aviation environment. This noninvasive oxygen monitoring apparatus warrants a highly objective analysis to investigate acute hypoxia tolerance. METHODS: Eight healthy male volunteers (20-25 years old) were exposed three times to a simulated altitude of 25,000 ft (7,620 m) at intervals of 7 days. We monitored arterial oxygen saturation (SaO2) and pulse rate by a pulse oximeter. The duration from taking the mask off to the time of 60% SaO2 was regarded as acute hypoxia tolerance. The venous hemoglobin concentration was measured a day before exposure to hypoxia. A questionnaire on the 14 subjective hypoxic symptoms was obtained after hypobaric chamber training. RESULTS: There were neither differences of acute hypoxia tolerance, hemoglobin concentration, nor pulse rate according to the repeated exposure of hypoxia. Four symptoms of sleepiness, fatigue, flushing and thinking impairment were sustained regardless of repeated exposures to hypoxia. But the incidence of symptoms of ear pain, anxiety, abdominal pain were reduced according to the repeated hypoxia. CONCLUSION: With pulse oximeter monitoring there was no difference between the values of time of 60% SaO2 in repeated exposures to hypoxia. The incidence of some subjective symptoms was reduced according to the repeated exposures to hypoxia.

STUDY ON ALTITUDE HYPOXIA TOLERANCE OF CHINESE WOMEN PILOT STUDENTS / 解放军医学杂志

0 05). But significant difference was found between them in blood pressure. So far as altitude hypoxia tolerance test is concerned, Chinese female pilots can fly a fighter as male pilots.

Pharmacodynamics Research of Lilium brownii Polysaccharide / 中药新药与临床药理

Objective To research the pharmacodynamics of lilium brownii Polysaccharide.Methods Five tests,including hypoxia tolerance test,serum content determination of SOD and MDA in mice,carbon clearance and weight determination of immune organ,content determination of serum hemolysin,and delayed-type hypersensitivity test were carried out to evaluate the main pharmacological indexes of lilium brownii Polysaccharide.Results Lilium brownii Polysaccharide can increase the hypoxia tolerance,anti-oxidation action and immuno-enhancing activity in mice.Conclusion Lilium browni Polysaccharide is one of the main active constituents of lilium brownii.