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At least 883 records · Page 49Linked to original sources
PubMed1971

Survival.

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Cold Temperature↗
PubMed1981

Reoxygenation of anoxic human tissues. An application for electron microscopy and its limits.

The reoxygenation technique originally used by Ferguson and Richardson (1978) for the revival and the ultrastructural improvement of tracheal and bronchial mucosae obtained post-mortem, has been applied to lung parenchyma, skin, liver, cerebellar cortex and skeletal muscle. The results show that the ultrastructural changes caused by post-mortem anoxia lasting 2 1/2-5 h were at least partially reversible in the alveolar epithelium and in the epidermis after 3 h reoxygenation in O2-saturated Krebs-Henseleit physiological solution at 37 degrees C. In contrast, reoxygenation was without any positive effect on anoxic changes in liver parenchyma, cerebellar cortex and skeletal muscle. The oxygen content of the immediate environment and temperature decrease are supposed to be the main protective factors influencing the reversibility of anoxia and thus affecting the results of reoxygenation. It might be expected that other superficially localized and air-exposed tissues (the nasal, paranasal, pharyngeal, laryngeal and oral mucosae, conjunctiva and cornea) could be revived or ultrastructurally improved by the reoxygenation technique.

Autopsy↗
PubMed1984

[A thermal chamber for the cold test in vasomotor disorders].

The cold test represents an essential part of the functional exploration of the vascular system performed in Raynaud's disease, but its physiological nature depends upon the use of a sufficiently large area of skin. Several measurements must be conducted simultaneously and various temperature ranges used to allow for the variable threshold of vascular reactivity to cold of different individuals. A thermal chamber is presented which enables the simultaneous performance of plethysmography, digital pressure recordings and capillaroscopy at different temperature ranges. A novel use of a laser flowmeter is also described. Peri-ungual capillaroscopy enables determination of the temperature, when capillary spasm appears and then is relieved during progressive cooling followed by reheating. This apparatus can be adapted for use of all techniques for exploration of vascular function.

Cold Temperature↗
PubMedDate not supplied

[Application of ESR saturation transfer spectroscopy for the study of molecular mobility of membrane proteins].

The principles and possibilities of saturation transfer spectroscopy--a new approach in the spin label method, enabling one to measure rotational correlation times up to 10(-3) s--are briefly discussed. This approach is applied to the study of the molecular mobility of a membrane protein Ca-dependent ATPase in native sarcoplasmic reticulum membranes and in egg yolk and dipalmitoyllecithin proteoliposomes using spin labels selectively attached to different SH-groups of a protein. The mobility of the labels on two SH-groups was shown to be due to the intramolecular motion of the protein polar head. It is independent of the protein concentration in membrane but is sensitive to substrate binding and to lipid environment. The correlation of this mobility with the ATPase activity was observed when changing lipid environment and temperature.

Animals↗
PubMed1984

[Flexible and rigid connections in the regulation of motor activity].

The present investigation deals with the problem of versatile and rigid connections (N.P. Bechtereva), their functions and interrelations during repeated stereotype movements. The necessity of the versatile connections in the course of motor activity is demonstrated. Versatility depends on permanent variations of the contractile capacity of muscles during physical work as a result of fluctuations of the internal environment (intramuscular temperature, oxygen saturation, metabolite concentration), of a different initial elongation of muscle fubers and a simultaneous contraction of muscles not directly related to the test muscle activity. It was shown that different loadings and different levels of training lead to a variability of the relationship between rigid and versatile connections.

Electrophysiology↗
PubMed1984

Acute physiological responses of squirrel monkeys exposed to hyperdynamic environments.

This study examined the responses of small primate, the squirrel monkey, to acute exposures to hyperdynamic environments. Body temperature, heart rate, and behavior of four restrained squirrel monkeys were recorded. After baseline monitoring at 1 G, monkeys were exposed to: a) +2 Gz for 60 min, b) a hyperdynamic profile simulating the gravitational envelope of the space shuttle during launch (8 min, +2.9 Gz max), or c) a simulated shuttle re-entry profile (19 min, +1.7 Gz max). In all experiments, the colonic temperature started to fall within 10 min of the onset of centrifugation and declined by as much as 2 degrees C in some conditions. This was in contrast to the stable body temperature observed during the baseline period. Also, the heart rate showed distinct elevations during centrifugation. Heart rate subsequently declined to baseline levels during the post-centrifugation phase. Behaviorally, after the onset of centrifugation, the animals periodically appeared to become drowsy and fall asleep. On the other hand, during the control period they tended to be alert, shifting their gaze about the cage. Thus, primates are susceptible to acute exposures to hyperdynamic fields, demonstrating significant physiological and behavioral changes.

Animals↗
PubMed1981

New gas-liquid equilibration method: syringe tonometer.

This new apparatus for gas-liquid equilibration (tonometry) in a transportable vessel is designed for tonometry of blood or buffer solution in a specially designed syringe. Gas enters the syringe chamber through small holes in the tip of the syringe plunger and bubbles upward through the sample. The syringe plunger is a second chamber, which is used for warming and humidifying the gas before it enters the tonometer chamber. The entire syringe is housed in a transparent, temperature-controlled environment during equilibration. After equilibration, the sample is easily entered into a blood-gas analyzer. At most, gas-liquid O2/CO2 equilibration for 2.5 mL of buffer or blood requires less than 13 min. Comparisons with a standard thin-film tonometer show good agreement for pO2 and pCO2 over the range 0-93 kPa (0-700 mmHg) and 2-20 kPa (14-150 mmHg), respectively. The syringe tonometer eliminates contamination of the sample during transfer and transport to the analyzer, thus making tonometry more technique-independent. The apparatus is simple and easy to use, with definite advantages over existing methods of tonometry.

Blood Gas Analysis↗
PubMed1976

Marijuana smoking and cold tolerance in man.

Ten men who were marijuana users served as subjects in a study of the effects of marijuana smoking on response to cold. Cold water (28 degrees C for 60 min) and cold air (20 degrees C for 120 min) mediums were utilized with three exposures in each medium. The three exposures followed smoking marijuana, smoking placebo, and a no-smoking control period. Additionally, a breathhold experiment preceded and followed the four smoking periods. Marijuana and placebo smoke were inhaled from a spirometer with each man receiving the smoke of 0.739 g of marijuana and placebo. Smoking marijuana did not greatly modify body heat content, since rectal temperature and most peripheral temperatures were not altered. However, temperatures over voluntary muscles likely to be involved in shivering were elevated. Heat production also greatly increased after marijuana, suggesting that it had stimulated shivering. Marijuana also produced tachycardia and abolished apneic bradycardia. The mechanism of this action is not clear, but some sympathetic involvement is indicated.

Adaptation, Physiological↗
PubMed1994

The Quechua manta pouch: a caretaking practice for buffering the Peruvian infant against the multiple stressors of high altitude.

The manta pouch--a caretaking practice of tightly swaddling and enclosing the infant in a set of cloths and blankets--and other caretaking practices are described for high-altitude resident (> 4,000 m) Quechua mother-infant pairs (N = 14). The manta pouch modifies the microenvironment inside the pouch so that, compared to the ambient environment, the temperature is higher and more stable, the humidity is higher, the partial pressure of O2 is lower, and stimulation levels are reduced. As the infant gets older, the characteristics of the pouch are modified such that the infant is increasingly exposed to ambient conditions. These caretaking practices may benefit the infant by buffering the infant from the multiple ecological stressors of high altitude, but they may also incur costs by exposing the infant to additional microenvironmental stressors (e.g., higher CO2 levels) and by reducing stimulation and limiting infant movement.

Adaptation, Physiological↗
PubMed1996

Heat propagation in dentin during instrumentation with different sonic scaler tips.

It is important to know how much heat is generated when a root surface is debrided with sonic scalers and if that heat can be released satisfactorily into the environment. The temperature changes that occurred in dentinal specimens treated with two different sonic scaler tips, used with and without coolant, were studied. Temperature increases of up to 4 degrees C were observed for both tips when a coolant was used. Heat propagation during instrumentation was dependent to a considerable degree on the temperature of the coolant. Sonic scalers should not be used without coolant, because the dentinal temperature may increase up to 35 degrees C, depending on the force of application. A high positive linear correlation was found between increase in temperature and force of application.

Dental High-Speed Equipment↗
PubMed1977

Exercise and heat orthostatism and the effect of heat acclimation and physical fitness.

Twelve trained and 16 untrained young men were administered five orthostatic tests while leaning upright against a wall, for 20 min--before exercise; after 60 min of exercise at a load of 40 W; after 15 min of exercise at a load of 80 W; after a Vo2 max test, and after 3 h of exercise at a load of 40 W in heat (39.4 degrees C DB, 30.3 degrees C WB). Eight of the untrained subjects were retested in the five orthostatic tests after 8 d of heat acclimation. The number of fainters in the orthostatic tests administered before exercise, after exercise at 40 W and 80 W, and after exercise in heat, were 3, 4, 6, and 13, respectively. There were no fainting episodes after the Vo2 max tests. Orthostatic responses in the different conditions were partially related. The trained subjects showed substantially better responses than the untrained ones (10% vs. 25% of fainting episodes), and heat acclimation resulted in marked improvement in orthostatism (decrease to 5% faintings). The results show that Vo2 max and heat tolerance account for most of the variability which determines orthostatic tolerance.

Acclimatization↗
PubMed1998

The Quantum Event of Oceanic Crustal Accretion: Impacts of Diking at Mid-Ocean Ridges

Seafloor diking-eruptive events represent the irreducible, quantum events of upper oceanic crustal accretion. They record events by which a large portion of the oceanic crust has formed through geological history. Since 1993, the U.S. Navy's real-time Sound Surveillance System has allowed location of ongoing acoustic signatures of dike emplacement and basalt eruptions at ridge crests in the northeast Pacific. These diking-eruptive events trigger a sequence of related, rapidly evolving physical, chemical, and biological processes. Magmatic volatiles released during these events may provide nutrients for communities of subseafloor microorganisms, some of which thrive in high-temperature anaerobic environments. Many of the organisms identified from these systems are Archaea. If microorganisms can thrive in the water-saturated pores and cracks within deep, volcanically active portions of our planet, other hydrothermally active planets may harbor similar life forms.

Journal Article↗