scholarly journals The effect of hydrophobic gases on the water fleaDaphnia magna

2021 ◽  
Author(s):  
K. Carlo Martín Robledo-Sánchez ◽  
J. C. Ruiz-Suárez
Keyword(s):  
Nitrous Oxide ◽  
High Pressures ◽  
Local Anaesthetics ◽  
Aquatic Invertebrate ◽  
Potential Models ◽  
Molecular Gases ◽  
Action Mechanisms ◽  
Invertebrate Animals ◽  
Transparent Windows ◽  
The Brain

AbstractIt is well known that some hydrophobic atomic and molecular gases provoke anaesthetic effects in mammal animals. Depending on the gas, there is a Minimum Alveolar Concentration (MAC) to produce anaesthesia. The gas enters in the lungs, dissolve in the blood and reaches the brain. Where are the targets and which are the action mechanisms are subjects not fully understood yet. Very recently, we reported the effects of local anaesthetics on the swimming behaviour of the water fleaDaphnia magna(STOTEN691, 278-283, 2019). Our aim now is to report new studies on the behaviour of this aquatic invertebrate in the presence of three hydrophobic gases: xenon, nitrous oxide and krypton. However, if local anaesthetics easily dissolve in water, these gases do not. Therefore, we designed a chamber to dissolve the gases using pressures up to 50 atmospheres. Simultaneously, we were able to measure in real time the response of the animals through transparent windows able to support such high pressures. Xenon and nitrous oxide effectively induce lack of movement in the daphnids. The effective pressures EP50for xenon and nitrous oxide were and 5.2 atmospheres, respectively. Krypton does not present clear effects on the motile suppression, even after the exposure to 44 atmospheres. Our findings provide insight on the physiological effects important gases used in human medicine produce in aquatic invertebrate animals considered as potential models to study anesthesia.

THE EFFECT OF AGE ON THE ELASTICITY OF THE MAJOR BRAIN ARTERIES

1965 ◽  
Vol 43 (2) ◽  
pp. 185-202 ◽  
Author(s):  
Douglas E. Busby ◽  
Alan C. Burton
Keyword(s):  
High Pressures ◽  
Mean Value ◽  
Collagen Fibers ◽  
Peripheral Arteries ◽  
Volume Data ◽  
Maximum Slope ◽  
Brain Arteries ◽  
Autopsy Specimens ◽  
Collagenous Fibers ◽  
The Brain

In previous work on peripheral arteries the law of Laplace has been applied to the pressure–volume data to yield the elastic constants and interrelation of function of elastin and collagenous fibers in the wall, and the changes with age. Similar analysis of major brain arteries has been made on autopsy specimens, aged 2 to 90. Volume (micrometer syringe) and pressure (electromanometer) in arterial segments were accurately measured. Absolute volumes were obtained by collapsing the artery with negative pressure, and the "unstretched circumferences" of the vessel were deduced from the curves. Tension–circumference curves were constructed. These showed the characteristic increasing slope (increased "elastance" or "stiffness") with increasing degree of stretch, interpreted as successive "recruitment" of collagen fibers as they reach their unstretched length.Increases in arterial length with distension were very small and negligible in vessels older than 30 years. Maximum slope (stiffness) was reached at pressures in the physiological range. The maximal stretch was 26 to 38% for vessels aged 30 to 90 years. This is less than for peripheral arteries, except those over 80 years old.Ageing showed itself mainly in reduction of the stretch required to bring 50% of the collagen fibers to their unstretched length, i.e. in the "degree of slackness". This was 30% stretch for younger vessels, 20% for the older. Unlike the peripheral arteries, the brain arteries show no significant increase with age in the maximal stiffness (related to their total collagen content). The mean value of the Young's modulus of the wall at high pressures was 1.93 ± 0.67 × 107 dynes/sq.cm. No significant change in thickness of the wall or lumen diameter with age was found.It is concluded that the major brain arteries are less distensible than peripheral arteries of comparable diameter, particularly in youth. Distensibility decreases with age, mainly because the "degree of slackness" of the collagen fibers is reduced. At physiological pressures the major resistance to distension is due to the collagen fibers rather than to the elastin fibers, which appear histologically to be less abundant, except in the elastica interna, than in peripheral arteries.

scholarly journals Tissue S-adenosylmethionine levels in fruit bats (Rousettus aegyptiacus) with nitrous oxide-induced neuropathy

1983 ◽  
Vol 50 (2) ◽  
pp. 325-330 ◽  
Author(s):  
J. van der Westhuyzen ◽  
J. Metz
Keyword(s):  
Nervous System ◽  
Nitrous Oxide ◽  
Fruit Bats ◽  
Fruit Bat ◽  
The Mean ◽  
The Brain ◽  
Mean Concentration

1. The effect of cobalamin inactivation by the anaesthetic gas nitrous oxide on the concentration of S-adenosylmethionine (Ado Met) in brain and liver of fruit bats (Rousettus aegyptiacus) was examined.2. Test animals exposed to N2O–oxygen (50:50, v/v) developed ataxia and paralysis leading to death after an average of 9·8 weeks (n 6). Animals receiving pteroylmonoglutamic acid supplements in the diet became ataxic earlier (mean 8·8 weeks) while those receiving methionine supplements survived for significantly longer periods (12·5 weeks, P < 0·01).3. Plasma cobalamin levels indicated severe depletion of cobalamin stores in N2O-exposed animals.4. The mean concentration of Ado Met in the brain of N2O-treated bats was nearly 50% higher than that of untreated controls. Ado Met levels in treated bats receiving pteroylmonoglutamic acid or methionine supplements were respectively 18 and 25% higher than in controls. In contrast, the concentration of Ado Met in the liver of all the N2O-treated groups was slightly lower than in controls.5. These results suggest that the N2O-induced neuropathy in the fruit bat is not related to a depletion of Ado Met in the nervous system.

scholarly journals NARCOSIS AND EMULSION REVERSAL BY INERT GASES

1957 ◽  
Vol 40 (4) ◽  
pp. 515-520 ◽  
Author(s):  
Dewey F. Sears ◽  
Wallace O. Fenn
Keyword(s):  
Nitrous Oxide ◽  
High Pressures ◽  
Chemical Properties ◽  
Inert Gases ◽  
Water Emulsion ◽  
Oil In Water ◽  
Oil In Water Emulsion

Investigations of the effect of high pressures of Na (100 to 130 atmospheres) and of Ar (60 to 80 atmospheres) showed that these gases are effective in reversing the phases of an oil in water emulsion. Nitrous oxide did not cause reversal at pressures as high as 53 atmospheres nor did helium as high as 107 atmospheres. We found CO2 most effective in reversing the emulsions and attributed this to its chemical properties. It is suggested that these observations may help to explain the narcotic effects of inert gases.

scholarly journals Prediction of live formation water densities from petroleum reservoirs with pressure-dependent seawater density correlations

DYNA ◽  
2020 ◽  
Vol 87 (213) ◽  
pp. 165-172
Author(s):  
Andrea Paola Sánchez Pérez ◽  
Wilson Antonio Cañas-Marín
Keyword(s):  
Pressure Range ◽  
High Pressures ◽  
Petroleum Reservoirs ◽  
Gas Content ◽  
Formation Water ◽  
Potential Models ◽  
Density Correlations

We studied two density correlations developed for seawater at high pressures as potential models to predict formation water densities from petroleum reservoirs as a function of salinity, pressure, gas content, and temperature. The correlations were tested against experimental densities measured at high pressures for live formation waters sampled under bottomhole conditions from five petroleum reservoirs. As a result, one of these seawater correlations was found to be particularly promising to predict formation water densities for these samples, even out of the pressure range originally reported for such a model.

Circulatory disturbances and changes in body temperature during anesthesia in brain surgery

1986 ◽  
Vol 67 (3) ◽  
pp. 194-195
Author(s):  
F. N. Kazantsev ◽  
E. Kh. Kamalov
Keyword(s):  
Nitrous Oxide ◽  
Brain Tumor ◽  
Body Temperature ◽  
Postoperative Period ◽  
Brain Surgery ◽  
Central Hemodynamics ◽  
Surgical Interventions ◽  
Balanced Anesthesia ◽  
The Brain ◽  
Circulatory Disturbances

To assess the adequacy of anesthetic protection during surgical interventions on the brain and in the postoperative period, it is necessary to monitor the central hemodynamics and body temperature regime. Therefore, we performed such control in 52 patients aged from 17 to 60 years old during the operative interventions on the brain under the conditions of intravenous balanced anesthesia with the use of sodium oxybutyrate or nitrous oxide and during 14-16 days in the postoperative period. All patients underwent bone-plastic craniotomy with opening of the dura mater. In 32 patients a brain tumor was removed, in 20 patients a subdural hematoma and cerebral detritus were removed.

Short-Term Learning and Interocular Transfer in Detour Experiments with Octopuses

1967 ◽  
Vol 47 (3) ◽  
pp. 393-408
Author(s):  
M. J. WELLS
Keyword(s):  
Interocular Transfer ◽  
Short Term ◽  
Optic Lobes ◽  
Memory Traces ◽  
Permanent Memory ◽  
Transparent Windows ◽  
The Brain

1. Octopuses will make detours down a corridor with opaque walls and will make a correct left-right choice at the far end in order to attack a crab seen to one side of the passage through the transparent windows of a home compartment. 2. In all, 1071 trials were carried out. In 883 of these a detour was completed, rightly or wrongly; in the remaining trials the octopuses failed to complete detours within 5 min. of the start of the trial. 3. The percentage of errors rose with the time spent in the maze. Animals that completed their runs within 20 or 30 sec. of entering the corridor rarely made a mistake; animals that took 2 min. or more, whether due to imposed delays (animal shut in the corridor) or to slow exploration of the maze, made as many errors as correct responses. 4. After removal of the vertical lobe from the brain the octopuses made more errors, particularly in the slower runs. There was also a higher proportion of trials at which they failed to complete a detour at all. These failures are not due to a failure of interocular transfer or to locomotor defects. 6. The results are discussed in relation to the function of the vertical lobe, interocular transfer, the nature of representations of recent events within the optic lobes and the establishment of more permanent memory traces in discrimination experiments.

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