Hypoxia

Background. The interests in mesenchymal stem cells (MSCs) and their application in cell therapy have resulted in a better understanding of the basic biology of these cells. Recently hypoxia has been indicated as crucial for complete chondrogenesis. We aimed at analyzing bone marrow MSCs (BM-MSCs) differentiation capacity under normoxic and severe hypoxic culture conditions.Methods. MSCs were characterized by flow cytometry and differentiated towards adipocytes, osteoblasts, and chondrocytes under normoxic or severe hypoxic conditions. The differentiations were confirmed comparing each treated point with a control point made of cells grown in DMEM and fetal bovine serum (FBS).Results. BM-MSCs from the donors displayed only few phenotypical differences in surface antigens expressions. Analyzing marker genes expression levels of the treated cells compared to their control point for each lineage showed a good differentiation in normoxic conditions and the absence of this differentiatio...

The main purposes of the present study were to substantiate the existence of the four types of performance categories (i.e., optimal-automatic, optimal-controlled, suboptimal-controlled, and suboptimal-automatic) as hypothesised in the multi-action plan (MAP) model, and to investigate whether some specific affective, behavioural, psychophysiological, and postural trends may typify each type of performance. A 20-year-old athlete of the Italian shooting team, and a 46-year-old athlete of the Italian dart-throwing team participated in the study. Athletes were asked to identify the core components of the action and then to execute a large number of shots/flights. A 2 × 2 (optimal/suboptimal × automated/controlled) within subjects multivariate analysis of variance was performed to test the differences among the four types of performance. Findings provided preliminary evidence of psychophysiological and postural differences among four performance categories as conceptualized within the MA...

During waterlogging conditions plants switch from aerobic respiration to anaerobic fermentation to cope with the lack of available oxygen. Plants have two main fermentation pathways: ethanol and lactic acid fermentation. In this paper we carry out a functional analysis of the Arabidopsis lactate dehydrogenase gene, LDH1. Our results indicate that LDH1, like some other anaerobic genes, is expressed in a root-specific manner and is affected by a variety of abiotic stresses (hypoxia, drought, cold) and mechanical wounding. Functional analysis of LDH1 was carried out using transgenic Arabidopsis overexpressing the gene (35S promoter) and a T-DNA knockout line. Overexpression of LDH1 resulted in improved survival of low oxygen stress conditions in roots but not in shoots. Increased lactic acid fermentation also resulted in significantly higher activities of pyruvate decarboxylase (PDC). Knockout mutants of LDH1 showed reduced survival under low oxygen conditions and PDC activity levels w...

The South American lungfish Lepidosiren paradoxa is an obligatory air-breathing fish possessing well-developed bilateral lungs, and undergoing seasonal changes in its habitat, including temperature changes. In the present study we aimed to evaluate gas exchange and pulmonary breathing pattern in L. paradoxa at different temperatures (25 and 30°C) and different inspired O2 levels (21, 12, 10, and 7%). Normoxic breathing pattern consisted of isolated ventilatory cycles composed of an expiration followed by 2.4±0.2 buccal inspirations. Both expiratory and inspiratory tidal volumes reached a maximum of about 35ml.kg(-1), indicating that L. paradoxa is able to exchange nearly all of its lung air in a single ventilatory cycle. At both temperatures, hypoxia caused a significant increase in pulmonary ventilation (V̇E), mainly due to an increase in respiratory frequency. Durations of the ventilatory cycle and expiratory and inspiratory tidal volumes were not significantly affected by hypoxia...

Purpose: Intermittent altitude exposure leads to improvements in aerobic performance and blood parameters of athletes. The variety of hypoxic devices and simulated altitude training models requires a detailed study of their effects to achieve the best results. The aim of this study was to investigate the effect of a four-week training camp at sea level conditions, combined with normobaric hypoxia, provided by hypoxicators during the night's sleep of the athletes. Material: Sixteen rowers of the Bulgarian national team (17.13±0.83 years old) were divided into a control group (n=8) and an experimental group (n=8) subjected to hypoxia for a period of four weeks. At the beginning and end of the training camp, anthropometric and hematological data were measured. A submaximal test on the Concept II rowing ergometer was performed, and the physical work capacity and anaerobic threshold were determined. Results: The results showed: 1) a lack of significant changes in the aerobic performance after training camp, both within and between groups; 2) at the end of the training camp in the experimental group a statistically significant increase in hemoglobin concentration (156.25±4.11 vs 162.75±4.11 g/L, p<0.01) and erythrocyte count (5.26±0.13 vs 5.49±0.10 g/L, p<0.01) was observed. Conclusions: The encouraging results regarding the higher increase in blood oxygen-carrying capacity in the experimental group did not lead to an increased working capacity. Further research should be provided in the search for optimal hypoxic training parameters, allowing not only a rise in hemoglobin concentration, but also the preservation of blood rheological properties.

ABSTRACT Salmon fish farmers are seeking methods to reduce infestations of salmon lice. The highest concentrations of salmon lice copepodites are typically found in the upper meters of the water column and preventing this water from passing through the salmon cages has been proposed as a way to reduce salmon lice infestation. One simple implementation proposed by the industry is to place a permanent tarpaulin skirt around the upper part of the sea cages. Currently, there is little evidence that a skirt will block the entrance of surface water to the cages and thereby reduce infestation. However, this pilot study shows that putting a tarpaulin skirt around a full scale commercial sea cage may seriously decrease the oxygen saturation levels available for the fish inside the skirt. Further investigations into the effectiveness of skirts as a means of reducing the exposure of farmed salmon to sea lice must therefore take precautional measures.

Global climate change is expected to intensify hypoxic conditions during coastal upwelling events along the west coast of North America, but the potential effects on nearshore fishes are not well understood. Viviparous rockfishes (genus Sebastes) that gestate and give birth during the upwelling season, such as gopher rockfish (S. carnatus), may be among the most affected. We tested the transgenerational effects of future hypoxic conditions on the metabolic status of gopher rockfish larvae. Four pregnant females were held during gestation in either ambient conditions (DO~8 mg/L) or a hypoxic treatment (DO~4 mg/L). A subset of larvae was sampled immediately post-parturition and remaining larvae were then split into two groups and placed in either control or hypoxic conditions for five days and sampled again. Citrate synthase (CS) and lactate dehydrogenase (LDH), proxies for aerobic and anaerobic metabolism, respectively, were assayed in pooled larval samples from all treatments. We expected that larvae would exhibit relatively greater reliance on aerobic metabolism (e.g., higher CS/LDH ratios) if exposure to hypoxia during pregnancy enhances larval performance to hypoxia post-parturition, compared with larvae from control mothers. We also expected that larvae from control mothers would exhibit relatively greater reliance on anaerobic metabolism if exposed to hypoxic post-parturition. Lastly, we hypothesized that larvae from hypoxic mothers would rely more on anaerobic metabolism immediately post-parturition. At birth, we found larvae from hypoxic mothers were more anaerobic compared to those from control mothers, but after five days we found trends that larvae from hypoxic mothers that continued developing in hypoxic conditions were more aerobic compared to those from control mothers. Our findings suggest the potential for larval gopher rockfish to exhibit a more aerobic phenotype when gestated during hypoxic conditions and placed in similar conditions post-parturition.

There are many factors in mucosal secretions that contribute to innate immunity and the 'first line of defence' at mucosal surfaces. Few studies, however, have investigated the effects of exercise on many of these 'defence' factors. The aim of the present study was to determine the acute effects of prolonged exercise on salivary levels of selected antimicrobial peptides (AMP) that have not yet been studied in response to exercise (HNP1-3 and LL-37) in addition to immunoglobulin A (IgA). A secondary objective was to assess the effects of exercise on saliva antibacterial capacity. Twelve active men exercised on a cycle ergometer for 2.5 h at approximately 60% of maximal oxygen uptake. Unstimulated whole saliva samples were obtained before and after exercise. There was a significant decrease (P < 0.05) in salivary IgA:osmolality ratio, following exercise, but IgA concentration and secretion rate were unaltered. Salivary HNP1-3 and LL-37 concentrations (P < 0.01 and P < 0.05, respectively), concentration:osmolality ratios (P < 0.01) and secretion rates (P < 0.01) all increased following exercise. Salivary antibacterial capacity (against E. coli) did not change. The increased concentration of AMPs in saliva may confer some benefit to the 'first line of defence' and could result from synergistic compensation within the mucosal immune system and/or airway inflammation and epithelial damage. Further study is required to determine the significance of such changes on the overall 'defence' capacity of saliva and how this influences the overall risk for infection.

Insects exhibit a remarkable array of adaptations that allow them to handle more or less severe hypoxia associated with numerous aquatic and terrestrial habitats. We consider these habitats and then discuss physiological, behavioral and morphological mechanisms that facilitate insect life under oxygen deprivation. Actually or potentially hypoxic habitats include aquatic systems, flood-prone soils and burrows, intertidal zones, ice encasement and high altitudes. Some microhabitats, including dung, carrion, mammalian alimentary canals, grain and wood, also are subject to hypoxia. Adaptations to hypoxia include the ability to switch from aerobic to anaerobic metabolic pathways (with attendant generation of end products), the ability to drastically attenuate basal metabolic rates, altered behaviors and enlarged tracheal system volumes. Research into the biology of hypoxia seems to be progressing from early observations of the abilities of some insects to withstand exposure to hypoxia or anoxia through studies of organismal mechanisms operating in hypoxia to detailed investigations of cellular and intracellular signaling processes. Our hope is this essay will help crystallize the emergent picture of this area for those interested in contributing to future research.

During the last 5 years, research on Human Activity Recognition (HAR) has reported on systems showing good overall recognition performance. As a consequence, HAR has been considered as a potential technology for e-health systems. Here, we propose a machine learning based HAR classifier. We also provide a full experimental description that contains the HAR wearable devices setup and a public domain dataset comprising 165,633 samples. We consider 5 activity classes, gathered from 4 subjects wearing accelerometers mounted on their waist, left thigh, right arm, and right ankle. As basic input features to our classifier we use 12 attributes derived from a time window of 150ms. Finally, the classifier uses a committee AdaBoost that combines ten Decision Trees. The observed classifier accuracy is 99.4%.

DATASET AVAILABLE AT: http://groupware.les.inf.puc-rio.br/har

A broad pattern of correlations between mechanisms of brain function impairment and self-transcendence is shown. The pattern includes such mechanisms as cerebral hypoxia, physiological stress, transcranial magnetic stimulation, trance-induced physiological effects, the action of psychoactive substances and even physical trauma to the brain. In all these cases, subjects report self-transcending experiences o en described as ‘mystical’ and ‘awareness-expanding,’ as well as self-transcending skills o en described as ‘savant.’ The idea that these correlations could be rather trivially accounted for on the basis of disruptions to inhibitory neural processes is reviewed and shown to be implausible. Instead, this paper suggests that an as-of-yet unrecognized causal principle underlying the entire pattern might be at work, whose further elucidation through systematic research could hold great promise.

Noninvasive ventilation [NIV] is used extensively in acute and chronic settings, at home, and in hospitals. It plays a pivotal role in managing respiratory failure during the COVID-19 pandemic with robust use in hospitals to avert the need for intubation as well as re-intubation. However, its use is associated with aerosol generation, which poses an immediate threat to all who work around it, like healthcare workers. Besides, domiciliary use is also associated with the same risk to the household and caregivers. Therefore, we need to plan the therapy and forge guidelines and recommendations to keep NIV safe during infections. Here we have reviewed the available literature and applied our experience to formulate guidelines and recommendations. However, updates and appraisals are evolving rapidly, and we need to keep our eyes open to tailor our approach.