Effects of helium and other inert gases on Echinosphaerium nucleofilium (protozoa, heliozoa)

1975 ◽  
Vol 63 (2) ◽  
pp. 467-481
Author(s):  
J. B. Miller ◽  
J. S. Aidley ◽  
J. A. Kitching
Keyword(s):  
Hydrostatic Pressure ◽  
Total Pressure ◽  
Cell Damage ◽  
Inert Gases ◽  
Gas Solubility ◽  
Reversal Effect ◽  
Pressure Reversal ◽  
Partial Pressures ◽  
Solubility Coefficients ◽  
Sites Of Action

The effects of helium, nitrogen, argon and krypton on Echinosphaerium nucleofilum (Heliozoa) have been studied at partial pressures of 10–130 atm. Additional experiments have been carried out with hydrostatic pressure alone. Helium causes shortening of the axopods over the whole range of pressures, and damage to the cell body at pressures of 60–90 atm, both with a maximum at 80 atm. These effects cannot be explained in terms of hydrostatic pressure alone; a ‘pressure reversal’ effect may be operating, causing the peak at 80 atm. Nitrogen also causes both cell damage and axopod shortening, the severity increasing with increasing pressure. Argon and krypton cause cell damage but no shortening. The order of potency for cell damage is krypton greater than argon greater than nitrogen greater than helium. It is suggested that there may be tuo sites of action, possibly the microtubules (for axopod shortening) and the cell membrane (for cell damage). In appropriate mixtures of helium and argon, both the cell damage usually caused by argon, and the axopod shortening usually caused by helium, are prevented. Possible mechanisms include the effects of hydrostatic pressure on gas solubility coefficients, reversal of the effects of the gases by the increase in total pressure, and competition for sites of action.

scholarly journals The Effect of Partial Pressures of Inert Gases on the Behaviour and Survival of the Heterotrich Ciliate Spirostomum Ambiguum

1976 ◽  
Vol 64 (3) ◽  
pp. 615-627
Author(s):  
S. MACDONALD ◽  
J. A. KITCHING
Keyword(s):  
Hydrostatic Pressure ◽  
Swimming Speed ◽  
Cell Damage ◽  
Inert Gases ◽  
Partial Pressures ◽  
Spirostomum Ambiguum ◽  
High Hydrostatic Pressures

A study has been made of the effects of helium, nitrogen and argon at partial pressures of 10–120 atm on the swimming speed, behaviour and survival of the heterotrich ciliate Spirostomum ambiguum. Experiments have also been carried out with hydrostatic pressure alone. Hydrostatic, helium and nitrogen pressures reduced the swimming speed approximately equally but pressure of argon reduced it to an even greater extent. Hydrostatic, helium, nitrogen and argon pressures caused a reduction in the number of reversals in a given time but the number of reversals/distance travelled did not change significantly. All the treatments increased the durations of individual forward movements. Pressures of helium, nitrogen and argon also increased the durations of reversals but at high hydrostatic pressures the durations of reversals were reduced. Argon caused cytolysis at 30–40 atm and nitrogen at 80 atm; helium did not cause any visible cell damage over periods of 1 h at 120 atm. Addition of substantial partial pressures of helium protected Spirostomum against partial pressures of argon which would otherwise have caused cytolysis. The increase of hydrostatic pressure may have been responsible.

Effects of hydrostatic pressure and inert gases on platelet aggregation in vitro

1990 ◽  
Vol 69 (6) ◽  
pp. 2239-2247 ◽  
Author(s):  
D. M. Pickles ◽  
D. Ogston ◽  
A. G. Macdonald
Keyword(s):  
Platelet Aggregation ◽  
Hydrostatic Pressure ◽  
Maximum Degree ◽  
Platelet Rich Plasma ◽  
Control Level ◽  
Inert Gases ◽  
Partial Pressures ◽  
Compression Cycle ◽  
Anesthetic Potency

A novel cuvette was used to subject citrated platelet-rich plasma (PRP) to high hydrostatic pressure with negligible contamination by He (used for compression of the apparatus). Aggregation was induced at pressure by ADP and quantified turbidimetrically. The maximum degree of aggregation (MDA) was reduced from a control level of 82.2 to 53.6% by exposure to 101 ATA. Because decompression bubbles did not form, aggregation was also measured immediately after a compression cycle. After exposure to 101 ATA hydrostatic pressure, platelets responded normally to ADP at 1 ATA. In a matching apparatus, PRP was equilibrated with high partial pressures of inert gases. Normal physiological plasma Po2 and pH were maintained during equilibration. N2O (5 ATA) reduced the MDA from 86.5 (control) to 58.1%. N2 (51 ATA) reduced the MDA from 74.7 (control) to 51.6%, and 101 ATA Pn2 reduced the MDA from 78.0 (control) to 32.3%. He (100 ATA) reduced the MDA from 83.6 to 38.6%. It was concluded that platelet aggregation was relatively sensitive to hydrostatic pressure and less sensitive to inert gases than predicted from their anesthetic potency ratios.

scholarly journals Growth of Streptococcus faecalis under High Hydrostatic Pressure and High Partial Pressures of Inert Gases

1968 ◽  
Vol 52 (5) ◽  
pp. 810-824 ◽  
Author(s):  
Wallace O. Fenn ◽  
Robert E. Marquis
Keyword(s):  
Growth Rate ◽  
Nitrous Oxide ◽  
Lactic Acid ◽  
Hydrostatic Pressure ◽  
Inert Gases ◽  
Inhibitory Potency ◽  
Streptococcus Faecalis ◽  
Volume Increase ◽  
Partial Pressures ◽  
Gas Pressures

Growth of Streptococcus faecalis in a complex medium was inhibited by xenon, nitrous oxide, argon, and nitrogen at gas pressures of 41 atm or less. The order of inhibitory potency was: xenon and nitrous oxide > argon > nitrogen. Helium appeared to be impotent. Oxygen also inhibited streptococcal growth and it acted synergistically with narcotic gases. Growth was slowed somewhat by 41 atm hydrostatic pressure in the absence of narcotic gases, but the gas effects were greater than those due to pressure. In relation to the sensitivity of this bacterium to pressure, we found that the volume of cultures increased during growth in a volumeter or dilatometer, and that this dilatation was due mainly to glycolysis. A volume increase of 20.3 ± 3.6 ml/mole of lactic acid produced was measured, and this value was close to one of 24 ml/mole lactic acid given for muscle glycolysis, and interestingly, close to the theoretic volume increase of activation calculated from the depression of growth rate by pressure.

Importance of oscillations in alveolar gas concentrations in the analysis of rebreathing data

1986 ◽  
Vol 61 (3) ◽  
pp. 1104-1113 ◽  
Author(s):  
K. H. Weisiger ◽  
G. D. Swanson
Keyword(s):  
Time Course ◽  
Continuous Process ◽  
Inert Gases ◽  
Accurate Estimation ◽  
Gas Solubility ◽  
Estimation Errors ◽  
Gas Uptake ◽  
Cyclic Model ◽  
Low Solubility ◽  
Cyclic Data

Cyclic rebreathing of a soluble inert gas can be used to estimate lung tissue volume (Vt) and pulmonary blood flow (Qc). A recently proposed method for analyzing such cyclic data (Respir. Physiol. 48: 255–279, 1982) mathematically assumes that ventilation is a continuous process. However, neglecting the cyclic nature of ventilation may prevent the accurate estimation of Vt and Qc. We evaluated this possibility by simulating the uptake of soluble inert gases during rebreathing using a cyclic model of gas exchange. Under cyclic uptake conditions alveolar gases follow an oscillating time course, because gas concentrations tend to increase during inspiration and to decrease during expiration. We found that neglecting these alveolar gas oscillations leads to the underestimation of soluble gas uptake by blood, particularly during the early rebreathing breaths. When continuous ventilation is assumed Vt and Qc are overestimated unless rapid rebreathing rates, large tidal volumes, and gases of moderately low solubility are used. Under these conditions the amplitude of the cyclic oscillations is minimized, the alveolar time course more closely resembles that expected from continuous ventilation, and the resulting errors are minimized. Alternatively, when the effect of oscillating alveolar gas concentrations on mass transfer are considered, these estimation errors can be eliminated without restricting rebreathing rate or gas solubility. We conclude that failure to consider the effect of cyclic rebreathing on the time course of alveolar gas concentrations may result in significant errors when evaluating rebreathing data for Vt and Qc.

scholarly journals Organosilica-Modified Multiblock Copolymers for Membrane Gas Separation

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3579
Author(s):  
Ilsia M. Davletbaeva ◽  
Alexander Yu. Alentiev ◽  
Zulfiya Z. Faizulina ◽  
Ilnaz I. Zaripov ◽  
Roman Yu. Nikiforov ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Toluene Diisocyanate ◽  
Multiblock Copolymers ◽  
Gas Solubility ◽  
Membrane Gas Separation ◽  
Modified Polymers ◽  
Temperature Relaxation ◽  
Solubility Coefficients ◽  
Modified Block ◽  
The Ideal

Organosubstituted silica derivatives were synthesized and investigated as modifiers of block copolymers based on macroinitiator and 2,4-toluene diisocyanate. A peculiarity of the modified block copolymers is the existence in their structure of coplanar rigid polyisocyanate blocks of acetal nature (O-polyisocyanates). Organosubstituted silica derivatives have a non-additive effect on high-temperature relaxation and α-transitions of modified polymers and exhibit the ability to influence the supramolecular structure of block copolymers. The use of the developed modifiers leads to a change in the gas transport properties of block copolymers. The increase of the permeability coefficients is due to the increase of the diffusion coefficients. At the same time, the gas solubility coefficients do not change. An increase in the ideal selectivity for a number of gas pairs is observed. An increase in the selectivity for the CO2/N2 gas pair (from 25 to 39) by 1.5 times demonstrates the promising use of this material for flue gases separation.

scholarly journals NOBLE GAS SOLUBILITY IN SUPER-CRITICAL WATER: IMPLICATIONS FOR INERT GAS STUDIES AND GEOCHRONOLOGY

1984 ◽  
Vol 23 (4) ◽  
pp. 483-490
Author(s):  
J. G. Mitchell ◽  
D. J. Terrell
Keyword(s):  
Low Temperatures ◽  
Volume Diffusion ◽  
Noble Gas ◽  
Inert Gases ◽  
Inert Gas ◽  
Gas Solubility ◽  
Transport Medium

Inert gases will ideally exhibit infinite miscibility with super-critical water.  The implications of this phenomenon are discussed in the context of the resetting of the K-Ar system during regional metamorhism, and emplacement of granites.  Inert gas abundances in oceanfloor rocks and shales may also be interpreted as a consequence (at least in part) of partioning between water and silicate phases in which the light inert gases are preferentially taken up in water.  The funtion of super-critical water as a transport medium for inert gases offers an important alternative to the unlikely process of volume diffusion at low temperatures.

Sequential V˙a/Q˙ distributions in the normal rabbit by micropore membrane inlet mass spectrometry

2000 ◽  
Vol 89 (5) ◽  
pp. 1699-1708 ◽  
Author(s):  
James E. Baumgardner ◽  
In-Cheol Choi ◽  
Anton Vonk-Noordegraaf ◽  
H. Frederick Frasch ◽  
Gordon R. Neufeld ◽  
...  
Keyword(s):  
Blood Sample ◽  
Mass Spectrometer ◽  
Sample Volume ◽  
Inert Gases ◽  
Inert Gas ◽  
Total Blood ◽  
Membrane Inlet Mass Spectrometry ◽  
Arterial Blood ◽  
Partial Pressures ◽  
Regression Techniques

We developed micropore membrane inlet mass spectrometer (MMIMS) probes to rapidly measure inert-gas partial pressures in small blood samples. The mass spectrometer output was linearly related to inert-gas partial pressure ( r 2 of 0.996–1.000) and was nearly independent of large variations in inert-gas solubility in liquid samples. We infused six inert gases into five pentobarbital-anesthetized New Zealand rabbits and used the MMIMS system to measure inert-gas partial pressures in systemic and pulmonary arterial blood and in mixed expired gas samples. The retention and excretion data were transformed into distributions of ventilation-to-perfusion ratios (V˙a/Q˙) with the use of linear regression techniques. Distributions ofV˙a/Q˙ were unimodal and broad, consistent with prior reports in the normal rabbit. Total blood sample volume for eachV˙a/Q˙ distribution was 4 ml, and analysis time was 8 min. MMIMS provides a convenient method to perform the multiple inert-gas elimination technique rapidly and with small blood sample volumes.

Molecular Hydrogen Attenuates High Hydrostatic Pressure-Induced Neuronal Cell Damage by Reversing Dysfunction of Mitochondrial Electron Transfer Chain

2021 ◽  
Author(s):  
Zhuoyang Lu ◽  
Tiantian Zhang ◽  
Yachong Hu ◽  
Hui Liu ◽  
Li Cui ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Cell Damage ◽  
Protective Agent ◽  
Protective Effects ◽  
Human Neuroblastoma ◽  
Electron Transfer Chain ◽  
Pathological Conditions ◽  
Transfer Chain

Abstract Cellular hydrostatic pressure beyond its normal range can induce the accumulation of reactive oxidative species (ROS) generated by mitochondria and lead to pathological conditions such as glaucomatous optic neuropathy. However, little is known about how the mitochondrial electron transfer chain (ETC) is affected by elevated pressure. Moreover, the protective effects of hydrogen on various pathological conditions have been observed by reductions in ROS, yet the role of hydrogen in high hydrostatic pressure (HHP)-induced cell damage remains obscure. The goal of this study was to investigate the effect of HHP on ETC activity and whether hydrogen exerts protective effects against HHP-induced damage in cultured neuronal cells. Cultured SH-SY5Y human neuroblastoma cells were exposed to an elevated ambient hydrostatic pressure of 50 mmHg for a period of 2 to 6 h. HHP impaired the activities of ETC complexes, and these effects were reversed by hydrogen. Significant increases in apoptotic rates and intracellular ROS levels were observed in HHP-treated SH-SY5Y cells. Hydrogen significantly inhibited the apoptotic rates and reduced the levels of ROS. These findings suggest that HHP induces cell damage by causing ETC dysfunction to increase oxidative stress and that hydrogen may act as a protective agent to alleviate HHP-induced neuronal injury.

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