Search Results
Results 351 - 400 of 804
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Horváth I S - - 2001
Furfural is an important inhibitor of yeast metabolism in lignocellulose-derived substrates. The effect of furfural on the physiology of Saccharomyces cerevisiae CBS 8066 was investigated using anaerobic continuous cultivations. Experiments were performed with furfural in the feed medium (up to 8.3 g/L) using three different dilution rates (0.095, 0.190, and ...
Gore C J - - 2001
This study investigated whether hypoxic exposure increased muscle buffer capacity (beta(m)) and mechanical efficiency during exercise in male athletes. A control (CON, n=7) and a live high:train low group (LHTL, n=6) trained at near sea level (600 m), with the LHTL group sleeping for 23 nights in simulated moderate altitude ...
Nacher M - - 2001
The role of the spleen during Plasmodium falciparum malaria in humans is unclear. In Thailand, malaria transmission is low and splenomegaly is rarer than in high transmission areas. We compared the prevalence of splenomegaly between 52 cerebral malaria patients and 191 patients without complications despite a high parasite biomass. We ...
Mazzeo R S - - 2001
Interleukin-6 (IL-6), an important cytokine involved in a number of biological processes, is consistently elevated during periods of stress. The mechanisms responsible for the induction of IL-6 under these conditions remain uncertain. This study examined the effect of alpha-adrenergic blockade on the IL-6 response to acute and chronic high-altitude exposure ...
Lundby C - - 2001
This study examined the effects of dopamine D(2)-receptor blockade on the early decrease in maximal heart rate at high altitude (4559 m). We also attempted to clarify the time-dependent component of this reduction and the extent to which it is reversed by oxygen breathing. Twelve subjects performed two consecutive maximal ...
Felici F - - 2001
The aim of this study was to evaluate the influence of exposure to altitude on muscle endurance during isometric contractions. Six sedentary subjects were studied. Surface electromyograph (sEMG) activity was recorded from the right biceps brachii (BB) during exhausting isometric exercise at 80% maximal voluntary contraction. Experiments were performed before, ...
Takeno Y - - 2001
Plasma volume (PV) expansion by endurance training and/or heat acclimatization is known to increase aerobic and thermoregulatory capacities in humans. Also, higher erythrocyte volume (EV) fractions in blood are known to improve these capacities. We tested the hypothesis that training in a hypobaric hypoxic and warm environment would increase peak ...
English N B - - 2001
Between A.D. 900 and 1150, more than 200,000 conifer trees were used to build the prehistoric great houses of Chaco Canyon, New Mexico, in what is now a treeless landscape. More than one-fifth of these timbers were spruce (Picea) or fir (Abies) that were hand-carried from isolated mountaintops 75-100 km ...
Mansoor J K - - 2001
PURPOSE: The purpose of this study was to examine the role of airway receptors in respiratory-related sensations after ascent to altitude. METHODS: Ratings of respiratory-related sensations, perceived exertion and acute mountain sickness, heart rate, and peripheral oxygen saturation were recorded at rest and exercise in male and female subjects who ...
Dudley R - - 2001
Studies of human exercise physiology have been conducted from a largely ahistorical perspective. This approach usefully elucidates proximate limits to locomotor performance, but ignores potential sources of biomechanical and physiological variation that derive from adaptation to ancestral environments. Phylogenetic reconstruction suggests that multiple hominoid lineages, including that leading to Homo ...
McClelland G B - - 2001
High-altitude acclimation alters lipid metabolism during exercise, but it is unknown whether this involves changes in rates of lipolysis or reesterification, which form the triacylglycerol/fatty acid (TAG/FA) cycle. We combined indirect calorimetry with [2-(3)H]glycerol and [1-(14)C]palmitate infusions to simultaneously measure total lipid oxidation, lipolysis, and rate of appearance (R(a)) of ...
Stray-Gundersen J - - 2001
Acclimatization to moderate high altitude accompanied by training at low altitude (living high-training low) has been shown to improve sea level endurance performance in accomplished, but not elite, runners. Whether elite athletes, who may be closer to the maximal structural and functional adaptive capacity of the respiratory (i.e., oxygen transport ...
Sandoval D A - - 2001
BACKGROUND: Previous research has found that exercise exacerbated acute mountain sickness (AMS) in men. PURPOSE: The current study tested this relationship in women taking oral contraceptives. METHODS: We studied seven women at 428 mmHg for 10 h; once while at rest (R) and once while performing intermittent exercise (EX). RESULTS: ...
Wozniak A - - 2001
PURPOSE: The aim of this work was an evaluation of the influence of physical exercise in high-altitude conditions (about 2000 m above sea level) on thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD) and catalase (CAT) activities in 10 kayakers and 10 rowers. METHODS: During their training, the sportsmen ...
Bruce T J - - 2001
Seven electrophysiologically active compounds were detected in air-entrained headspace samples of live flowers of Tagetes erecta analyzed by gas chromatography (GC) linked to a female Helicoverpa armigera electroantennograph (EAG) using polar and nonpolar capillary columns. These compounds were subsequently identified using GC linked to mass spectrometry as benzaldehyde, (S)-(-)-limonene, (R,S)-(+/-)-linalool, ...
Burtscher M - - 2001
OBJECTIVE: To evaluate the efficacy of aspirin for headache when exercising during acute high-altitude exposure. BACKGROUND: Aspirin effectively prevents headache when mostly resting during acute high-altitude exposure. However, the majority of individuals exposed to high altitude perform mountaineering activities, which might trigger headache. DESIGN: Randomized, double-blind, placebo-controlled trial. METHODS: Thirty-one ...
Joanny P - - 2001
Eight subjects were placed in a decompression chamber for 31 days at pressures from sea level (SL) to 8848 m altitude equivalent. Whole blood lipid peroxidation (LP) was increased at 6000 m by a mean of 23% (P<0.05), at 8000 m by 79% (P<0.01) and at 8848 m by 94% ...
Yuan Y L - - 2001
Twenty cross combinations were made with 4 recessive glandless lines (gl2gl2 gl3gl3) used as females and 5 dominant glandless lines (Gl2eGl2e Gl3Gl3) used as male parents to estimate the genetic variance components of kernel oil and protein content of seeds, oil and protein index, and kernel index using a genetic ...
Burtscher M - - 2001
Worldwide there are approximately 100 million visitors to high altitude annually and about 15% of those are elderly. Nevertheless, basic information on the cardiopulmonary and metabolic responses to physical activity at high altitude in the elderly is scarce. Therefore, we studied 20 voluntary healthy elderly subjects (55-77 years) who were ...
Liu J - - 2001
It is generally perceived that biodiversity is better protected from human activities after an area is designated as a protected area. However, we found that this common perception was not true in Wolong Nature Reserve (southwestern China), which was established in 1975 as a "flagship" protected area for the world-renowned ...
Meeuwsen T - - 2001
The goal of this study was to investigate to what extent intermittent exposure to altitude in a hypobaric chamber can improve performance at sea-level. Over a 10-day period, elite male triathletes trained for 2 h each day on a cycle ergometer placed in a hypobaric chamber. Training intensity was 60-70% ...
Hahn A G - - 2001
Despite equivocal findings about the benefit of altitude training, current theory dictates that the best approach is to spend several weeks living at > or =2500 m but training near sea level. This paper summarizes six studies in which we used simulated altitude (normobaric hypoxia) to examine: (i) the assumption ...
Gudjonsdottir M - - 2001
The effect of high altitude (HA) on exercise-induced diaphragm fatigue in normal subjects was examined. Eight normal subjects completed an incremental exercise test at sea level (SL) and at 3,325 m. Before (baseline), during, and after exercise (recovery), maximal transdiaphragm pressure (Pdi,sniff), breathing pattern, and diaphragmatic effort (PTPdi) were measured. ...
Gueresi P - - 2001
BACKGROUND: The study is part of a research project on the marital structure of mountain populations from the Eastern Italian Alps. Little is known about marriage patterns in this Alpine area. AIM: The aim of the study is to evaluate the extent of reproductive isolation in some communities of the ...
Conkin J - - 2001
BACKGROUND: We define lower body adynamia (LBA) as restricted lower body movement, particularly walking, during both the denitrogenation phase at site pressure and during the exercise phase while at altitude. HYPOTHESIS: Our null hypothesis is that subjects who are adynamic in the lower body but do upper body exercise will ...
Bentler R A - - 2001
OBJECTIVE: Investigators at the National Acoustic Laboratories have provided a theoretical derivation and experimental validation of a formula for setting the maximum output of hearing aids (Dillon & Storey, 1998; Storey, Dillon, Yeend, & Wigney, 1998). Given that measurement of discomfort levels for setting maximum output can be both time-consuming ...
Weston A R - - 2001
PURPOSE: The time course of physiological exercise responses after acute ascent to moderate altitude was investigated. METHODS: Fifteen young male subjects (16.5 +/- 0.8 yr) completed one familiarization and then two further sea level sessions to determine sea level values (SL). Subjects were then tested 6 h (ALT1), 18 h ...
Bärtsch P - - 2001
The most reliable prediction of high altitude tolerance can be derived from the clinical history of previous comparable exposures. Unfortunately, there are no reliable tests for prediction prior to first-time ascents. Although susceptibility to AMS is usually associated with a low hypoxic ventilatory response (HVR), there is too much overlap ...
Hahn A G - - 2001
Acute exposure to moderate altitude is likely to enhance cycling performance on flat terrain because the benefit of reduced aerodynamic drag outweighs the decrease in maximum aerobic power [maximal oxygen uptake (VO2max)]. In contrast, when the course is mountainous, cycling performance will be reduced at moderate altitude. Living and training ...
Levine B D - - 2001
For training at altitude to be effective, it must provide some advantage above and beyond similar training at sea level. This advantage could be provided by: 1) acclimatization to altitude which improves oxygen transport and/or utilization; 2) hypoxic exercise which "intensifies" the training stimulus; or 3) some combination of both. ...
Caillet S - - 2001
Bulk atmospheric deposition of 7Be and 210Pb has been measured at Versoix, close to Geneva, Switzerland. Collectors were continuously deployed from November 1997 through November 1998 for periods from 1 to 22 days depending on the frequency of rain. The activities of 7Be and 210Pb integrated over the sampling interval ...
Arnold U - - 2001
The method of limited proteolysis has proven to be appropriate for the determination of unfolding rate constants (k(U)) of ribonuclease A in the transition region of thermal denaturation [Arnold, U. & Ulbrich-Hofmann, R. (1997) Biochemistry 36, 2166-2172]. The aim of the present paper was to extend this procedure to the ...
Drinkall M J - - 2001
Fifteen trials were undertaken to determine the effectiveness of spinosad for the control of Frankliniella occidentalis on a range of glasshouse ornamentals. A range of dose rates were tested from 6-15 g as hl-1. A high level of control (> 90%) was achieved at most assessments of both nymphs and ...
El-Migdadi F - - 2001
This study was designed to investigate the effect of exercise at 350 m below sea level altitude (-350 m) on the serum levels of lactate dehydrogenase (LDH), insulin, and lactate. The study was carried out on ten trained adult males with mean age of 23.3 +/- 3.4 years following a ...
Wilber R L - - 2001
Recently, endurance athletes have used several novel approaches and modalities for altitude training including: (i) normobaric hypoxia via nitrogen dilution (hypoxic apartment); (ii) supplemental oxygen; (iii) hypoxic sleeping devices; and (iv) intermittent hypoxic exposure (IHE). A normobaric hypoxic apartment simulates an altitude environment equivalent to approximately 2000 to 3000m (6560 ...
Lundby C - - 2001
We have measured maximal heart rate during a graded maximal bicycle exercise test to exhaustion in five healthy climbers before and during an expedition to Mt. Everest. Maximal heart rates at sea level were 186 (177-204) beats/min(-1) at sea level and 170 (169-182) beats/min(-1) with acute hypoxia. After 1, 4 ...
Lundby C - - 2001
The purpose of the present study was to investigate the degree to which peak heart rate is reduced during exhaustive exercise in acute hypoxia. Five sea-level lowlanders performed maximal exercise at normobaric normoxia and at three different levels of hypobaric hypoxia (barometric pressures of 518, 459, and 404 mmHg) in ...
Mazzeo R S - - 2001
We have previously documented the importance of the sympathetic nervous system in acclimatizing to high altitude in men. The purpose of this investigation was to determine the extent to which alpha-adrenergic blockade affects the sympathoadrenal responses to exercise during acute high-altitude exposure in women. Twelve eumenorrheic women (24.7 +/- 1.3 ...
Foster P P - - 2000
For altitude decompressions, we hypothesized that reported onset times of limb decompression illness (DCI) pain symptoms follow a probability distribution related to total bubble volume [V(b.)(t)] as a function of time. Furthermore, we hypothesized that the probability of ever experiencing DCI during a decompression is associated with the cumulative volume ...
Foster P P - - 2000
In response to exercise performed before or after altitude decompression, physiological changes are suspected to affect the formation and growth of decompression bubbles. We hypothesized that the work to change the size of a bubble is done by gas pressure gradients in a macro- and microsystem of thermodynamic forces and ...
Keyl C - - 2000
This study was performed to investigate the influence of breathing control on the autonomic cardiac regulation at high altitude in adapted and non-adapted awake subjects. We recorded electrocardiogram and pulse oximetry in 14 short-term acclimatized lowlanders and 14 Himalayan Sherpas during resting conditions at an altitude of 5,050 m. Spectrum ...
Hendricks D M - - 2000
BACKGROUND: Supplemental oxygen delivered by mask at high altitude is used to increase arterial oxygen saturation (SaO2) thereby mitigating physiological and cognitive dysfunction secondary to hypoxemia. Historically, mask performance has not been well documented although it may be a critical factor in determining the success of an expedition. METHODS: Three ...
Wickler S J - - 2000
This study had two goals: 1) measure hematologic changes with high-altitude acclimatization in horses; and 2) assess the effect of 9 days at high altitude on subsequent athletic performance at low altitude. Six horses performed standardized exercise tests on a dirt track (before and during time at altitude) and treadmill ...
Brutsaert T D - - 2000
Arterial oxygen saturation (SaO(2)) was measured at 3,600-3,850 m by pulse oximetry at rest and during submaximal exercise in three study groups: 1) highland Aymara natives of the Bolivian altiplano (n = 25); 2) lowland European/North American sojourners to the highlands with at least 2 months of acclimatization time to ...
Jansen G F - - 2000
BACKGROUND AND PURPOSE: Impaired cerebral autoregulation (CA) from high-altitude hypoxia may cause high-altitude cerebral edema in newcomers to a higher altitude. Furthermore, it is assumed that high-altitude natives have preserved CA. However, cerebral autoregulation has not been studied at altitude. METHODS: We studied CA in 10 subjects at sea level ...
Green H J - - 2000
Exposure to altitude results in a reduction in partial pressure of oxygen in the arterial blood and a reduction in oxygen content. In an attempt to maintain aerobic metabolism during increased effort, a series of acclimatization responses occur. Among the most conspicuous of these responses is an increase in hemoglobin ...
Mazzeo R S - - 2000
The purpose of this investigation was to determine the sympathoadrenal response to exercise in women after acclimatization to high altitude. Sixteen eumenorrheic women (age, 23.6 +/- 1.2 years; weight, 56.2 +/- 4.3 kg) were studied at sea level and after 10 days of high-altitude exposure (4,300 m) in either the ...
Moore L G - - 2000
Studies of ventilatory response to high altitudes have occupied an important position in respiratory physiology. This review summarizes recent studies in Tibetan high-altitude residents that collectively challenge the prior consensus that lifelong high-altitude residents ventilate less than acclimatized newcomers do as the result of acquired 'blunting' of hypoxic ventilatory responsiveness. ...
Purkayastha S S - - 2000
BACKGROUND: Little is known about work performance of women in hypobaric hypoxia. Moreover, whether native women of moderate altitude (2,000-2,100 m) differ from their lowland counterparts in their ability to adjust to hypobaric hypoxia is also not known. Hence, physiological alterations on work performance due to mountaineering training with altitude ...
Palmowski A M - - 2000
High and low contrast multifocal ERG (MF-ERG) recordings were obtained from the right eyes of 24 patients with OAG (high-tension OAG: n=16, low-tension OAG: n=8) and compaired to those recorded from 18 healthy volunteers. High contrast MF-ERG recordings were obtained at a mean luminance of 100 cd/m2 with a contrast ...
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