Search Results
Results 401 - 450 of 1038
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Stumm G - - 2001
The high pressure neurological syndrome (HPNS), a neurological condition during elevated pressure especially in deep diving, has been simulated with experimental animals. Rats were subjected to 61 bars with slow pressure increase and one or two hours constant high pressure; subsequently the pressure was released to sea level within 20 ...
Ferretti G - - 2001
In this paper, the respiratory, circulatory and metabolic adjustments to human extreme breath-hold diving are reviewed. A survey of the literature reveals that in extreme divers, adaptive mechanisms take place that allow prolongation of apnoea beyond the limits attained by non-diving subjects, and preservation of oxygen stores during the dives. ...
Schagatay E - - 2001
This study addressed the interaction between short-term adaptation to apneas with face immersion and erythrocyte release from the spleen. Twenty healthy volunteers, including ten splenectomized subjects, participated. After prone rest, they performed five maximal-duration apneas with face immersion in 10 degrees C water, with 2-min intervals. Cardiorespiratory parameters and venous ...
Neubauer B - - 2001
OBJECTIVES: Increased ambient pressure and oxygen partial pressure (pO2) influence cardiovascular regulation during diving and caisson work. We measured the cardiac output (Q) in subjects who practiced moderate work at a usual diving depth of 30 m. METHODS: In 23 healthy male Navy divers who performed steady state bicycle exercises ...
González S - - 2001
This study set out to determine the possible influence of variations in atmospheric pressure on mortality in the Madrid Autonomous Region (MAR), taking into account the possible confounding effect of other atmospheric variables. The study was based on daily mortality data from the MAR Revenue and Excise Authority, meteorological data ...
Poulsen S A - - 2001
The synthesis of enantiomerically pure C-6 substituted pyrazolo[3,4-d]pyrimidines has been performed by aromatic nucleophilic substitution of 4-amino-6-chloro-1-phenylpyrazolo[3,4-rd]pyrimidine under conditions of high pressure at ambient temperature. Conventional synthetic conditions (reflux at atmospheric pressure) were unsuccessful. The S enantiomer 11 displayed higher affinity and selectivity for the adenosine A1 receptor than the ...
Darbin O - - 2001
In rat, helium pressures induce locomotor and motor activity which requires dopaminergic and N-methyl-D-aspartate (NMDA) receptor activities at striatal level. However, biochemical studies have suggested that pressure exposure may increase striatal glutamate level. We used microdialysis technique to study the effects of pressure on glutamate level in the striatum and ...
Bianchi-Demicheli F - - 2001
Objective: This study examined the influence of weather conditions on the incidence of outpatient emergency consultations at the Department of Obstetrics and Gynecology at the Regional Hospital in Lugano, Switzerland. Study Design: The medical records of all women who attended the outpatient emergency unit at the Department for Obstetrics and ...
Sheriff D D - - 2001
INTRODUCTION: In humans, +Gz exposure immediately preceded by exposure to zero or -Gz can result in unexpected incapacitation ("push-pull" effect). Our goals were to establish whether this phenomenon exists in rats and to evaluate the importance of varying the duration of -Gz exposure on magnitude of the push-pull effect on ...
Kawaguchi H - - 2001
Mechanical forces related to pressure and flow are important for cell hypertrophy and proliferation. To test the hypothesis that mechanosensors are present that are sensitive solely to pure atmospheric pressure in the absence of shear and tensile stresses. A pressure-loading apparatus was set up to examine the effects of atmospheric ...
Berberich J A - - 2000
Selection of biocompatible solvents is critical when designing bioprocessing applications for the in situ biphasic extraction of metabolic end-products. The prediction of the biocompatibility of supercritical and compressed solvents is more complicated than for liquid solvents, because their properties can change significantly with pressure and temperature. The activity of the ...
Riches P E - - 2000
The Knoop indenter has been used to characterise fully the Knoop microhardness (H(K)) anisotropy of compact bone. 2120 indentations were performed on mature ovine radii and a linear relationship was found between H(K) and the angle between the major diagonal of the indenter and the lamella boundaries (p<<0.001). H(K) increased ...
Sanz P D - - 2000
A comprehensive vision of the heat transfer process involved in high-pressure shift freezing (HPSF) is shown in comparison to the process at atmospheric pressure. In addition, a mathematical model to predict the freezing times is presented. This model takes into consideration the dependence of the thermophysical properties relating to temperature ...
Theron M - - 2000
Previous studies have suggested that the efficiency of oxidative phosphorylation in the freshwater eel (Anguilla anguilla) is increased after acclimation to high hydrostatic pressure. Analysis at atmospheric pressure of the respiratory chain complexes showed that, after 21 days at 10.1 MPa, the activity of complex II was decreased to approximately ...
Finn J P - - 2000
Barometric pressure exerts by far the greatest influence of the three environmental factors (barometric pressure, temperature and humidity) on power outputs from air-braked ergometers. The barometric pressure correction factor for power outputs from air-braked ergometers is in widespread use but apparently has never been empirically validated. Our experiment validated this ...
Taylor D M - - 2000
STUDY OBJECTIVES: To examine the psychometric and cardiac effects of pseudoephedrine at 1 and 3 atmospheres (atm) of pressure (0 and 66 feet of sea water, respectively), and to make recommendations about the agent's safety in the diving environment. DESIGN: Double-blind, placebo-controlled, crossover study. SETTING: Monoplace hyperbaric chamber of a ...
Taylor D M - - 2000
STUDY OBJECTIVES: To examine the psychometric and cardiac effects of dimenhydrinate at 1 and 3 atmospheres (atm) of pressure (0 and 66 feet of sea water, respectively), and to make recommendations about the drug's safety in the diving environment. DESIGN: Double-blind, placebo-controlled, crossover study SETTING: Monoplace hyperbaric chamber of a ...
Sébert P - - 2000
The hexose part of glycolysis has been studied in the freshwater Chinese crab Eriocheir sinensis exposed to high pressure (101 ATA, i.e. 1000 m depth) at 14 degrees C and in normoxic conditions. Glycolytic fluxes (from glucose, JA and from Glucose 6 Phosphate, JB) have been determined using NADH depletion ...
Hälinen A I - - 2000
The purpose of this study was to characterize the respiratory effects of single and repeated controlled exposures to clean warm humid and cold dry air in a new model of anesthetized, mechanically ventilated guinea pigs, and to compare findings with known effects in humans. Intratracheal air (T(tr)) and retrotracheal tissue ...
Dean J B - - 2000
We developed a hyperbaric chamber for intracellular recording in rat brain stem slices during continuous compression and decompression of the tissue bath with the inert gas helium. Air, rather than helium, was also used as the compression medium in some cases to increase tissue nitrogen levels. An important feature is ...
Dromsky D M - - 2000
We developed a swine model to describe the untreated natural history of severe decompression sickness (DCS) after direct ascent from saturation conditions. In a recompression chamber, neutered male Yorkshire swine were pressurized to a predetermined depth from 50-150 feet of seawater [fsw; 2.52-5.55 atmospheres absolute (ATA)]. After 22 h, they ...
Nightingale J A - - 2000
Epidemiologic evidence suggests a link between morbidity and mortality and levels of particulate matter in the atmosphere. We studied the inflammatory response to inhalation of diesel exhaust particulates (DEP) in normal volunteers. DEP were collected from the exhaust of a stationary diesel engine and were resuspended in an exposure chamber. ...
Ryerson N V - - 2000
This study investigated the effect of pressurized atmosphere on the size and number of voids in dental stones and investments. Control specimens of casts and invested patterns were bench set. Experimental specimens of casts and invested patterns were allowed to set under pressure. The specimens were then sectioned and voids ...
Webb J T - - 2000
INTRODUCTION: Space Shuttle extravehicular activity (EVA) requires decompression from sea level pressure (14.7 psia) to a 4.3 psia (30,300 ft) pressure suit. The transition currently involves altering the shuttle atmosphere to allow shirt-sleeve denitrogenation to occur during a 12 to 36-h staged decompression (SD) at 10.2 psia (9,800 ft) with ...
Yoles E - - 2000
Age is a natural factor that has been found to significantly affect sensitivity to hyperbaric hyperoxia (HBO). Exposure to HBO may lead to damages in the energy metabolism of the brain cells. The aim of this study was to test the effect of HBO on the metabolic, hemodynamic and electrical ...
Belo I - - 2000
The effects of increased air pressure in a culture of the thermophilic microorganism Thermus sp. RQ-1 were investigated. Cell growth dependence on oxygen supply was investigated in a fermenter at atmospheric pressure. Total oxygen depletion from the medium for low values of kLa was observed during the exponential growth phase. ...
Jauchem J R - - 2000
Relatively large thermal gradients may exist during exposure of an animal to microwaves (MWs), particularly at high frequencies. Differences in thermal gradients within the body may lead to noticeable differences in the magnitude of cardiovascular changes resulting from MW exposure. This study compares the thermal distribution and cardiovascular effects of ...
Lacey J P - - 2000
Barotrauma is defined as an injury due to pressure differences between atmospheric and intratympanic pressures. Human beings are well suited to operate within an environment involving small alterations in atmospheric pressure. Man's persistence in operating outside this environment leads to exposure to large pressure differentials with resulting trauma. External, middle, ...
Dohgomori H - - 2000
We evaluated the accuracy of delivery of one type of infusion pump at three nominal flow rates under two environmental pressures (measured in atmospheres absolute, ATA), one of which is used for hyperbaric oxygenation. Overall, we observed significant differences between the two different pressures (1 ATA and 2 ATA). Changes ...
Suarez-Varel M M - - 2000
Spontaneous pneumothorax (SP) is a common respiratory condition that is easily recognized and treated, though the etiology remains largely unknown. Apart from individual factors, it has been suggested that changes in atmospheric pressure may trigger the onset of SP. Our aim was to examine the association between the onset of ...
Parker E C - - 2000
Individual crewmember escape from a disabled U.S. Navy nuclear submarine has never been necessary, but remains an important contingency. Decompression sickness (DCS) is one of the foreseeable risks and a robust mathematical model of DCS incidence has been used to estimate the magnitude of this risk under a variety of ...
Darbin O - - 2000
In mammals high pressure of helium-oxygen (He-O2) breathing mixture leads to the high pressure neurological syndrome (HPNS) which includes a set of behavioural disorders such as locomotor and motor hyperactivity (LMA) and myoclonia. In rats, i.c.v. administrations of competitive NMDA antagonists decrease some of these symptoms suggesting that He-O2 pressure ...
Thomas P S - - 2000
Increasing numbers of patients are receiving hyperbaric oxygen therapy as an intensive care treatment, some of whom have pre-existing airway obstruction. Spirometers are the ideal instruments for measuring airway obstruction, but peak flow meters are useful and versatile devices. The behaviour of both types of device was therefore studied in ...
Dudley R - - 2000
Recent geophysical analyses suggest the presence of a late Paleozoic oxygen pulse beginning in the late Devonian and continuing through to the late Carboniferous. During this period, plant terrestrialization and global carbon deposition resulted in a dramatic increase in atmospheric oxygen levels, ultimately yielding concentrations potentially as high as 35% ...
Saito S - - 2000
A transportable hyperbaric chamber durable for 15 psi of pressure was used to treat a patient suffering from moderate acute mountain sickness at 3700 m above sea level. The symptoms were ameliorated a few minutes after pressurization in the chamber. After a 20-minute stay in the chamber, the patient was ...
Huang E T - - 2000
A novice scuba diver with an implanted ventriculo-peritoneal (VP) shunt inquired about the performance characteristics of his shunt while diving. A literature search revealed no information regarding shunt performance under hyperbaric conditions. The manufacturer could not certify that the shunt would function under pressure. Therefore, four VP shunts were tested ...
Abraini J H - - 1999
High helium pressure of more than 2 MPa produces central neuroexcitatory motor behavior. In rodents, symptoms comprise locomotor and motor activity (LMA), myoclonia, and, at pressure greater than 9-10 MPa, convulsions and tonic-clonic seizures. We studied the behavioral effects of bilateral injection of the glutamate uptake inhibitor L-trans-pyrollidine-2,4-dicarboxylic acid (L-trans-PDC), ...
Sugihara G - - 1999
We use residual-delay maps of observational field data for barometric pressure to demonstrate the structure of latitudinal gradients in nonlinearity in the atmosphere. Nonlinearity is weak and largely lacking in tropical and subtropical sites and increases rapidly into the temperate regions where the time series also appear to be much ...
Enstipp M R - - 1999
Heart rates were recorded from double-crested cormorant chicks during their first ever and subsequent voluntary head submergences and dives, as well as during longer dives made after the chicks were accustomed to diving. Despite variation between chicks, the cardiac response to first ever and subsequent voluntary submergence (head submergences and ...
Peters N T - - 1999
PURPOSE: To evaluate the effect of increased atmospheric pressure on visual acuity in patients who have had radial keratotomy (RK). SETTING: Long Beach Memorial Medical Center, Long Beach, California, USA. METHODS: This controlled clinical study comprised 4 eyes that had RK and 4 control eyes that were age and sex ...
Tetzlaff K - - 1999
The purpose of this study was to evaluate respiratory effects of wet and dry hyperbaric chamber dives to 0.6 MPa ambient pressure in healthy males. There were 19 and 22 subjects who participated in two series of dives with a bottom time of 15 min and decompression times of 28 ...
Soulat J M - - 1999
BACKGROUND: characterize To the effects of high asbestos exposure during annual periods of insulation. METHOD: 170 ex-workers underwent clinical examination, spirometry, standard chest X-rays and high-resolution computed tomography (HRCT). Asbestos exposure was retrospectively assessed for latency, duration, and intensity. RESULTS: Sixty-six percent of these workers were annually exposed to high ...
Timmins G S - - 1999
This study investigates the respiratory physiology of bioluminescent larvae of Pyrearinus termitilluminans in relation to their tolerance to hypoxia and hyperoxia and to the supply of oxygen for bioluminescence. The partial pressure of oxygen (P(O2)) was measured within the bioluminescent prothorax by in vivo electron paramagnetic resonance (EPR) oximetry following ...
Ponganis PJ - - 1999
To evaluate blood N(2) uptake and the role of the respiratory volume (air sacs/lungs) as a N(2) and O(2) reservoir in deep-diving penguins, diving respiratory volume (Vdr), heart rate (fh), venous P(N)(sum), blood volume (V(b)) and hemoglobin (Hb) concentration were measured in king penguins (Aptenodytes patagonicus) during forced submersions and ...
Hill V M - - 1999
An aqueous glucose-lysine model system (initial pH 10.1) was incubated at 60 degrees C and atmospheric pressure (system A) or 600 MPa (system B) to the same absorbance value at 420 nm. Volatile reaction products were isolated by solvent extraction and analyzed by gas chromatography/mass spectrometry. Thirty-two compounds were identified; ...
Spira A - - 1999
Diving is a high-risk sport. There are approximately between 1 to 3 million recreational scuba divers in the USA (with over a quarter-million learning scuba annually); there are about 1 million in Europe and over 50,000 in the United Kingdom. In this population 3-9 deaths/100,000 occur annually in the US ...
Hanna J M - - 1999
The effects of climate and altitude on casual blood pressure are examined from the perspectives of initial exposure, acclimatization, long-term residence, and birthplace. Hot arid and hot humid climates seem to have little effect on blood pressure, although a slight reduction may be found in some naturally acclimatized groups. Exposure ...
Lenzen M - - 1999
Measurements of the 222Rn and 220Rn concentration in air, the atmospheric pressure, and the air sample temperature were carried out in an abandoned gypsum mine in Walferdange, Luxembourg. The 222Rn concentration shows a negative correlation with the atmospheric pressure and a tentative positive correlation with gravity variations. The results suggest ...
Kumar R - - 1999
OBJECTIVE: A composite Indian herbal preparation-I (CIHP-I) containing ingredients derived from 7 different plants and asphalt was tested for its adaptogenic activity and its mechanism of action was investigated. DESIGN: CIHP-I was tested using the cold-hypoxia-restraint (C-H-R) animal model in which the restrained rats were exposed to 5 degrees C ...
Diarra G M - - 1999
Oxygen consumption of single mosquitoes was measured using a differential pressure transducer (DPT) connected to two small chambers. A mosquito was placed in the experimental chamber (P1) and was separated from NaOH by 4 cm2 of marquisette mesh. The reference chamber (P2) contained the same amount of NaOH and the ...
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