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Results for “Atmospheric Pressure”

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At least 19 recordsLinked to original sources
PubMed1979

The survival and implantation of mouse blastocysts at varying degrees of reduced atmospheric pressure.

Pregnant mice were exposed to reduced atmospheric pressures ranging from 630 to 390 mm Hg during the pre-implantation and implantation periods and the numbers of embryos surviving 85 hours post coitum compared with those in litter-mate controls. Even at a pressure of 630 mm Hg (= 1,550 mm Hg) there was a significant fall in numbers of normal blastocysts and rise in abnormal forms before implantation, and implantation sites were reduced in number. The numbers of abnormal forms increased and implantation sites decreased at lower pressures, suggesting strongly that the hypoxia of reduce atmospheric pressure was responsible for the abnormalities observed. The pre-implantation period appears to be one during which the fertilised ovum is at particular risk, both of hypoxic damage and of failure to implant. Implantation may afford a degree of protection against hypoxia.

Animals↗
PubMed1978

Low atmospheric pressure effects on wearing soft contact lenses.

The majority of all research in the field of contact lenses has taken place in a normal, ground-level environment. The purpose of this study was to determine if any changes occurred in wearing hydrophilic soft lenses under conditions of low atmospheric pressures. The effects on visual acuity, refraction, keratometry, and biomicroscopy were investigated with eight naval volunteers while wearing soft contact lenses at simulated altitudes up to 30,000 ft (9144 m) in an aviation hypobaric chamber. The results indicated that the low atmospheric pressure at high atitude in itself did not affect the fit of soft contact lenses.

Aerospace Medicine↗
PubMed1979

Real-time analysis of breath using an atmospheric pressure ionization mass spectrometer.

A new technique is reported resulting in the direct, instantaneous analyses of trace compounds in breath. The analyses were performed using a commercial atmospheric pressure chemical ionization mass spectrometer (TAGA TM2000 APCI mass spectrometer). A known flow of breath sample is introduced into the ionization region of the mass spectrometer. The study includes the measurement and monitoring in real-time, of breath ammonia during a 24 hour and a 48 hour period. The ammonia profiles indicate a personalized daily pattern associated with each subject. This method appears to be of potential value in routine detection and treatment of hyperammonemia patients. Results also show that it is possible to obtain instantaneous analyses of several naturally occurring metabolites and other substances on breath in the ppm to ppt range, suggesting a number of diagnostic research applications.

Air↗
PubMed2024

Simulation and experimental study of a cold atmospheric pressure plasma and comparison of efficiency in boosting recombinant Endoglucanase II production in Pichia pastoris.

Recombinant proteins are essential in various industries, and scientists employ genetic engineering and synthetic biology to enhance the host cell's protein production capacity. Stress response pathways have been found effective in augmenting protein secretion. Cold atmospheric pressure plasma (CAP) can induce oxidative stress and enhance protein production. Previous studies have confirmed the applicability of CAP jets on Phytase and green fluorescent protein (GFP) production in Pichia pastoris hosts. This study investigates the effect of CAP treatment on another valuable recombinant protein, Endoglucanase II (EgII), integrated into the Pichia pastoris genome. The results demonstrated that plasma induction via two different ignition modes: sinusoidal alternating current (AC) and pulsed direct current (DC) for 120, 180, and 240 s has boosted protein secretion without affecting cell growth and viability. The AC-driven jet exhibited a higher percentage increase in secretion, up to 45%. Simulation of plasma function using COMSOL software provided a pattern of electron temperature (Te) and density distribution, which determine the plasma cocktail's chemistry and reactive species production. Furthermore, electron density (ne) and temperature were estimated from the recorded optical spectrum. The difference in electron properties may explain the moderately different impressions on expression capability. However, cell engineering to improve secretion often remains a trial-and-error approach, and improvements are, at least partially, specific to the protein produced.

Plasma Gases↗
PubMed1978

Myocardial collagen, the effects of right ventricular hypertrophy and its involution induced by changes in atmospheric pressure.

Right ventricular hypertrophy induced by hypobaric conditions was accompanied by an increased collagen mass. Left ventricular collagen was unaffected. Right ventricular mass remained unchanged after involution of right ventricular hypertrophy on return to normobaric conditions. Dietary restriction limited the size and collagen mass of both ventricles.

Animals↗
PubMedDate not supplied

[Effectiveness of using oxygen at different periods of increased atmospheric pressure action (experimental studies)].

The allowable value of nitrogen supersaturation was determined in 4 dogs during 219 experiments in a hyperbaric atmosphere (2 and 3 ata) which simulated diving. In the course of a 1-and 4-hour exposure of dogs to increased pressures of oxygen and an inert gas the allowable value may either decrease or increase. In order to increase the value, it is most effective and reliable to allow a 20-minute prebreathing of oxygen at 2--3 ata.

Animals↗
PubMed1977

[Experimental study in rats to reduce carbon monoxide in the blood induced by cigarette smoke, by inhaling oxygen at atmospheric pressure].

When animals are exposed to cigarette smoke, the concentration of carbon monoxide in blood is rapidly increased, so that intensive inhalation tests cannot be carried out. A simple apparatus is described to expose Rats alternatively to cigarette smoke and to oxygen in order to reduce the concentration of carbon monoxide in the blood. This method makes it possible to increase the daily administration of smoke considerably; nevertheless, under such conditions, lung tumors were not observed.

Animals↗
PubMed1975

The influence of environmental agents on prostaglandin biosynthesis and metabolism in the lung. Inhibition of lung 15-hydroxyprostaglandin dehydrogenase by exposure of guinea pigs to 100 per cent oxygen at atmospheric pressure.

Enzymes in the 100 000g supernatant fraction of guinea-pig lungs, in the presence of NAD-+, converted PGF-2 alpha (prostaglanding F-2 alpha) into a less-polar compound. The u.v. spectrum of this metabolite showed a strong absorption band at 230 nm, which is characteristic of a carbonyl group in conjugation with a double bond. Reduction of this metabolite with NaBH4 resulted in a compound that behaved like PGF2 ALPHA on t.l.c. and g.l.c. From this evidence we concluded that PGF2alpha is metabolized in vitro to 15-oxo-PGF2 alpha by the NAD-+-dependent prostaglandin dehydrogenase system of guinea-pig lung. The effect of exposure of the animal to SO-2 and O2 on the rate of prostaglanding biosynthesis and catabolism by lung fractions in vitro was studied. Exposure of guinea pigs to 500 p.m. of SO2 for 5h or to 50p.p.m for 9 days (6h/day) did not alter the production or degradation of prostaglandings by lung fractions in vitro. In contrast, exposure of guinea pigs to 100% O2 for 48 h inhibited the rate of prostaglanding metabolism in vitro by 60-70% without significantly altering the rate of biosynthesis by lung fractions. Inhibition of prostaglandin dehydrogenase activity in vitro by lung fractions after exposure of the animal to O2 was dependent on the duration of exposure. Gluthathione S-aryltransferase and catechol O-methyltransferase activites of guinea-pig lung 100 000g supernatant were unaltered by exposure of the animal to O2. Thus it appears that inhibition of pulmonary prostaglandin dehydrogenase by exposure of the animal to O2 is not the result of a general toxic response. It was postulated that the inhibition of prostaglanding dehydrogenase may occur after exposure of the animal to other oxidant gases.

Alcohol Oxidoreductases↗