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PubMedDate not supplied

[State of microcirculation and cellular hemostasis in men with borderline arterial hypertension during thermoneutral "dry" water immersion].

Platelet hemostasis, microcirculation, blood viscosity and lipid metabolism were examined in 18 men with borderline hypertension and 8 healthy men before, during and after 7-day immersion. The exposure to thermoneutral dry water immersion produced hypercoagulopathic changes of platelet hemostasis in the healthy and hypertensive subjects. Platelet hemostasis returned to the pretest level in the healthy subjects 2 days and in the hypertensive subjects only 5 days after exposure. Prior to immersion the hypertensive subjects showed signs of capillarotrophic insufficiency which increased after exposure. On immersion day 3 the hypertensive subjects exhibited a higher blood viscosity and a larger content of total lipids and free fatty acids. All the parameters returned to normal 2 days after immersion.

Blood Viscosity↗
PubMed1985

The effect of leakage on the insulation provided by immersion-protection clothing.

The effect of controlled, incremental water leakage on the thermal insulation provided by three immersion-protection assemblies has been measured using a thermal manikin. The results show an average loss of 30% of the initial insulation for a leak of 500 g, 40% for a leak of 1000 g, and nearly 60% for a leak of 3000 g. The assemblies differed only in the thermal insulation layer which consisted of: A. A single thickness of wool (initial immersed insulation 0.63 clo) B. A double thickness of wool (initial immersed insulation 0.79 clo) and C. A layer of polypropylene batting between nylon covers (initial immersed insulation 0.76 clo). Differences between the assemblies in loss of insulation with leakage were small and no evidence was found to support claims that the insulating properties of polypropylene are more resistant to wetting than those of wool. It is considered that the substantial loss of insulation even with small leaks makes it essential that tests of the water-excluding performance of immersion suits are undertaken in realistic conditions rather than in calm water.

Body Temperature Regulation↗
PubMed1984

Body cooling in human males by cold-water immersion after vigorous exercise.

Five male subjects were immersed to neck level in a whole-body water calorimeter (water temperature 19 degrees C) on two occasions. One immersion was preceded by 30 min of exercise on a treadmill at 80% of the subjects' maximum heart rate, while the other was preceded by no exercise (control). Ventilation, oxygen consumption, hand-grip strength, and heat loss (measured by calorimetry) results showed no significant differences between resting and exercise trials. Minute ventilation and oxygen consumption increased during the immersion but the magnitude of the increase varied among subjects. There was a significant decrease is isometric hand-grip strength after 30 min of immersion. Rectal temperatures fell faster (0.031 degree C +/- 0.004 degree C/min) for exercised subjects than for controls (0.019 degree C +/- 0.005 degree C/min) between 10 and 45 min of immersion (P less than 0.01). It appears that vigorous preimmersion exercise may shorten survival time in cold water due to an increase in cooling rate.

Adult↗
PubMed1983

[Physical exertion tolerance after water immersion].

Before and after 24-hour water immersion test subjects performed a submaximal workload on a bicycle ergometer. Changes in their hematocrit, circulating plasma volume and fluid balance were compared with those during immersion. As a result, the test subjects were subdivided into two groups. For one group the workload was very hard; adaptation to immersion was accompanied by significant renal losses of fluid from the intra- and extravascular space. The bicycle ergometry test after immersion demonstrated a decrease of exercise tolerance combined with circulatory disorders. The other group showed a higher exercise tolerance; after immersion exercise tolerance remained high at the expense of the reserves that maintained optimal blood supply to the working muscles.

Adult↗
PubMedDate not supplied

[Kidney function and the glucocorticoid activity of the adrenal cortex during immersion].

The paper presents the study of renal and adrenal function in six normal men during and after 3-day water immersion used as weightlessness simulation. The renal excretion of fluid, basic electrolytes, creatinine and total 17-hydroxycorticosteroids (17-HOCS) for 24 hours and following a provocative water-load test (20 ml/kg) was measured. During the first post-immersion day diuresis increased by 77%, excretion of sodium by 42%, 17-HOCS by 43% and creatinine by 34% as compared to the pre-immersion level. Potassium excretion remained essentially unchanged. The circadian rhythm of excretion of the above substances was normal: at night the excretion decreased and in the morning increased noticeably. The study of renal function and adrenal activity was carried out 56 hours after the beginning of water immersion, using a provocative water-load test. Water excretory and osmoregulatory functions of kidneys, and glucocorticoid activity of adrenals remained normal. These data give evidence that during a 60 hour exposure to water immersion no functional hypocorticism develops.

17-Hydroxycorticosteroids↗
PubMed1995

Effect of triazolam on responses to a cold-water immersion in humans.

Managing alertness of soldiers during sustained operations is a source of serious concern for military unit commanders. A frequently employed strategy is to induce sleep before an operation, especially operations requiring prolonged travel. Sleep-inducing drugs could have an action on thermoregulation through their effect on alertness and a possible direct effect on the brain. The goal of this study was therefore to evaluate the effect of a commonly prescribed triazolam (Halcion) on thermoregulatory responses to cold-water immersion. Eight subjects were immersed twice in 18 degrees C water for up to 90 min in the morning; once after ingesting 0.25 mg triazolam (TRZ) the prior evening, and again after placebo (PLB) treatment. There were no significant differences between trials for mean duration of the immersion, the change in rectal temperature and mean skin temperature. Total metabolic heat production was similar for both conditions: 767 +/- 107 vs. 781 +/- 105 kj.m-2 for TRZ and PLB, respectively. The results should be considered in light of a large variation among the subjects in sensitivity to TRZ, which was unrelated to biometrical characteristics such as surface area-to-mass ratio, lean body mass, % body fat, and physical fitness. Although not statistically significant, there was a trend for a smaller increase in plasma free fatty acid and glycerol concentrations after water immersion with TRZ. The results suggest that the ingestion of a single dose of triazolam 11 h prior to a cold-water immersion is not likely to accelerate the rate of onset of hypothermia. Individual sensitivity, however, may predispose some sensitive subjects to negative effects in this regard.

Adipose Tissue↗
PubMed1993

Are beta-endorphins and thermoregulation during cold-water immersion related?

The purpose of this investigation was to determine the relationship between core temperature (Tre), tissue insulation (I), and beta-endorphins (beta-END) during immersion in cold water. To test this, 21 males were immersed to the first thoracic vertebra for 120 min in stirred water at either 18 degrees, 22 degrees, or 26 degrees C. Subjects were divided with respect to body fat [high fat (HF) = 18-22%, n = 11; low fat (LF) = 8-12%, n = 10] and randomly assigned to one of the three temperatures. Blood was drawn at 25 and 5 min (T-25 and T-5, respectively) before immersion, after 1 h of immersion, and 5 min before the completion of the second hour (T + 60 and T + 120, respectively). No significant relationship was found between delta beta-END and delta I or delta Tre. The relationship between the changes in thermoregulatory variables and delta beta-END did not differ between the HF and LF groups. Also, beta-END (adjusted for plasma volume) was lower (P < 0.05) in the HF vs. the LF group. beta-END (pg.ml-1) increased (P < 0.05) as time increased from T-25 to T + 60 and were not progressive with duration of immersion. Thus, beta-END did not increase in proportion to level of heat loss.

Adult↗
PubMed1993

Blood volume reduction counteracts fluid shifts in water immersion.

Six healthy men were bled by 15% of their total blood volume (TBV) before 7 h of seated water immersion to test the hypothesis that some of the major physiological responses to an expansion of central blood volume can be counteracted by prior reduction of TBV. Subjects were their own controls under two conditions: seated dry in air and seated immersed to the suprasternal notch in water. Immersion without prior reduction of TBV (WC = Wet Control) caused a statistically significant 22% increase in cardiac output (CO), 368% increase in urine production, and 200% increase in sodium excretion relative to dry control (DC) sessions. When TBV was reduced before immersion, CO was the same as during DC sessions; however there were significant increases above DC in urine flow (+73%) and sodium excretion (+120%), although they were significantly reduced from WC values. Potassium excretion was similar during DC and WC sessions, but was significantly increased (+75%) when subjects were immersed after 15% reduction of TBV.

Adult↗
PubMed1995

CO2 chemosensitivity during immersion in humans.

Hypercapnic ventilatory response was compared in 9 seated subjects during head-out immersion in 35 degrees C (thermoneutral) water and during non-immersion in 28 degrees C (thermoneutral) room air. Using Read's CO2-rebreathing technique, minute ventilation (VE) and end-tidal (ET) PCO2 were sampled continuously for 4-5 min with a spirometer and a mass spectrometer, while the subject rebreathed a 6 L gas mixture initially containing 7% CO2 and 93% O2 in a bag-in-box system. The slope of the hypercapnic ventilatory response curve, expressed as delta VE/delta PETCO2, ranged from 0.76 to 2.49 L/min/mmHg. Immersion affected neither the slope nor the position of the hypercapnic ventilatory response curve. The rate of rise of PETCO2 during immersed CO2-rebreathing was significantly reduced (4.47 +/- 0.19 [SE] mmHg/min), as compared to the control value (5.67 +/- 0.24). It was concluded that the CO2 chemosensitivity during immersion in humans did not change and that the capacity to store CO2 in tissue might have been increased.

Administration, Inhalation↗
PubMed1991

Immersion events in residential swimming pools. Evidence for an experience effect.

BACKGROUND: --Drowning and near-drowning in residential swimming pools are leading causes of morbidity and mortality for young children. We tested the hypothesis that the period immediately after a pool is acquired is a time of high risk for these events. This study was also designed to provide population-based data on swimming pool immersion events, regardless of severity. METHODS: --We conducted a mail survey of a probability sample of Sacramento County, California, households with in-ground swimming pools in January 1988; 80% of eligible subjects responded. Onset of exposure to a pool was defined as the month in which (1) the responding household had a pool installed, or (2) the responding household first occupied a residence with a pool. Exposures began in 1959 through 1987. RESULTS: --The home swimming pool immersion event rate was 11 per 1000 pool-years. The rate per 1000 pool-years was higher for the first 6 months of exposure than thereafter (0 to 6 months, 44; 7 to 24 months, 14; greater than 24 months, seven), but 77% of events occurred outside the high-risk period. For households whose exposures began in 1984 through 1987, the immersion event rate was 51 per 1000 pool-years overall and 123 per 1000 pool-years for the first 6 months of pool exposure; these increases probably represent underreporting of earlier events. In this group, 48% of events occurred outside the high-risk period. The family swimming pool accounted for 91% of immersion events at the respondents' homes. CONCLUSIONS: --The residential swimming pool is an important hazard for pool-owning households. The first 6 months of exposure constitute a high-risk period, but many immersion events occur later. Pool drowning prevention programs may focus on newly acquired swimming pools and their owners but should be as broad as possible to maximize their effectiveness.

California↗
PubMed1994

Induction of heat shock protein and prevention of caerulein-induced pancreatitis by water-immersion stress in rats.

Water-immersion stress is known to be involved in the development of hemorrhagic pancreatitis in caerulein-induced pancreatitis, when the stress is given following caerulein injection. The effects of pre-treatment with water-immersion to caerulein-induced pancreatitis were investigated in this study. 1. A 60-kDa heat shock protein was induced by pre-treatment with water-immersion stress in the pancreas. 2. Intra-peritoneal injection of caerulein (40 micrograms/kg) induced acute pancreatitis in rats without pre-treatment with water-immersion. However, when the rats were pre-treated with water-immersion, acute pancreatitis was not developed and no change of serum amylase levels was observed by i.p. injection of caerulein.

Amylases↗
PubMed1991

Effect of depth of immersion in the waterbath on the effectiveness of electrical stunning in chickens.

Broiler chickens were electrically stunned either by immersing their heads, necks and upper breast in a waterbath stunner or by immersing their heads only. The time to recovery of muscular activity was assessed, and it was found that the deeper immersion was associated with a slightly (10 second) shorter time to resumption of head righting. When hens which had previously been implanted with electroencephalogram electrodes were electrically stunned it was found that the incidence of somatosensory evoked responses during the first 60 seconds after applying the current was not influenced by the depth of immersion. It was concluded that depth of immersion had little influence on the effectiveness of electrical stunning.

Animal Welfare↗
PubMed2006

Ocular and facial injuries associated with the use of immersion heaters in an inmate population.

PURPOSE: To report ocular and facial injuries caused by the use of electric immersion heaters in an inmate population. DESIGN: Prospective observational case series. METHODS: Data were recorded over a six-month period on age, gender, mechanism of injury, examination, and treatment of Dallas County inmates who experienced ophthalmic injuries from immersion heaters and were referred to a tertiary-care center. RESULTS: Eight male inmates were treated for thermal ocular injuries, which occurred within jail cells as a result of cooking explosions from electric immersion heaters, known by inmates as "stingers." All patients had thermal eyelid burns, either first- or second-degree facial burns, and corneal abrasions with corneal edema. Corneal metallic foreign bodies were removed in one patient, and three patients underwent debridement for corneal sloughing. CONCLUSIONS: Immersion heater-related accidents may cause thermal injuries within the inmate population. Physicians evaluating incarcerated patients with ocular trauma should be aware of immersion heaters as a common cause.

Adolescent↗
PubMed2005

Effects of immersion in virtual reality on postural control.

In the present study, we examined the effects of the time lag between visual scene and the head movement in the virtual reality (VR) world on motion sickness and postural control in healthy volunteers. After immersion in VR with additional time lags (from 0 to 0.8 s) to the inherent delay (about 250 ms), the visual-vestibular conflict induced a slight motion sickness in experimental subjects, but no change was noticed in the body sway path with eyes open and closed. However, Romberg ratio of body sway path with eyes closed divided by that with eyes open after immersion in VR was significantly decreased in comparison with that before immersion in VR. Since Romberg ratio is an index of visual dependency on postural control, this finding indicates that the immersion in VR decreases the visual dependency on postural control. It is suggested that adaptation to visual-vestibular conflict in VR immersion increases the contribution of vestibular and somatosensory inputs to postural control by ignoring the conflicting delayed visual input in the VR world. VR may be a promising treatment for visual vertigo in vestibular patients with unsuccessful compensation by its ability to induce vestibular and somatosensory reweighing for postural control.

Adult↗
PubMed1998

Biphasic elevation of plasma histamine induced by water immersion stress, and their sources in rats.

The effect of water immersion stress on the plasma concentration of histamine, in Wistar and mast cell-deficient (Ws/Ws) rats, was investigated. The histamine content of the plasma, skin and gastric mucosa, as well as the level of activity of histidine decarboxylase in the gastric mucosa, were determined by high performance liquid chromatography (HPLC)-fluorometry. In Wistar rats exposed to water immersion stress for a total of 6 h, an initial, acute, four-fold, transient increase in the plasma histamine level, followed by a sustained, though lower, elevation of the plasma histamine level, was observed. The initial acute increase in plasma histamine level was also seen in gastrectomized Wistar rats exposed to water immersion stress, but not in Ws/Ws rats exposed to stress. The sustained elevation of the plasma histamine level was observed in the Ws/Ws rats. However, in both the gastrectomized Wistar rats and gastrectomized Ws/Ws rats, the sustained elevation in plasma histamine level was not observed. The histamine content of the skin of Wistar rats after 15 min or more exposure to water immersion stress, was 20% lower than that of control rats. The mucosal histamine content of both Wistar rats and Ws/Ws rats, was 20% lower, whereas histidine decarboxylase activity in the gastric mucosa was enhanced by two-fold, during exposure to stress for 4 h. These findings indicate that water immersion stress causes a biphasic increase in plasma histamine concentration in Wistar rats; the initial acute increase in plasma histamine level originates from mast cells, and the second, sustained increase is attributed to enterochromaffin-like cells.

Animals↗
PubMed2001

Fabrication of poly(phosphoester) nerve guides by immersion precipitation and the control of porosity.

Immersion precipitation was employed as a method for the fabrication of polymeric conduits from P(BHET-EOP/TC), a poly(phosphoester) with an ethylene terephthalate backbone, to be applied as guidance channels for nerve regeneration. Coatings of various porosities could be obtained by immersing mandrels coated with a solution of the polymer in chloroform into non-solvent immersion baths, followed by freeze or vacuum-drying. The porosity of the coatings decreased with an increase in polymer molecular weight, drying time before precipitation and concentration of polymer solution. The effects of these parameters can be rationalized by employing ternary phase diagrams, where porosity is directly related to the degree of phase separation available to the system before gelation occurs. To afford improved porosity control, a new system was developed which employed the contrasting phase-separation behavior of P(BHET-EOP/TC)/chloroform solution in methanol and water. As water is essentially a non-solvent for the polymer, the demixing boundary of the P(BHET-EOP/TC)-CHCl3-H2O system is located close to the polymer-solvent edge of the phase diagram, while that of the P(BHET-EOP/TC)-CHCl3-MeOH system is located further away. A mixture of methanol and water allows the demixing boundary to be shifted to intermediate coordinates. By immersing P(BHET-EOP/TC) coatings in immersion baths containing different ratios of water and methanol, then gradually titrating the bath with methanol to a concentration of 70% (v/v) methanol, surface porosities ranging from 2 to 58% could be achieved.

Biocompatible Materials↗
PubMed1987

Perfusion-fixation of the human brain for immunohistochemistry: comparison with immersion-fixation.

A method of perfusion-fixation of the human brain is described and compared with immersion-fixation by immunoperoxidase staining for several substances (tyrosine hydroxylase, substance P, choline acetyltransferase, glutamate decarboxylase, Met-enkephalin, and neuron-specific enolase) in human striatum. Results from 1-cm slices fixed by immersion for 1, 2, 4 and 8 days were compared with results from slices of perfused brain postfixed for the same time periods. The fixative used in all steps was 4% paraformaldehyde at 4 degrees C. In the immersion-fixed brains, optimal immunoreaction for tyrosine hydroxylase and glutamate decarboxylase was limited to a depth of 1-2 mm from the surface of the brain slice. In contrast, staining density in perfusion-fixed brains was relatively homogeneous and of high quality. The other antigens studied displayed more uniform staining throughout the section with both perfused and immersed brains. Investigators intending to study human brain immunohistochemistry using immersion-fixation should be aware of the possibility of depth-related variations in staining intensity and would be wise to determine whether this effect is significant for the antigens they choose to study.

Aged↗
PubMed1997

Effects of noxious hindpaw immersion on evoked and spontaneous firing of contralateral convergent dorsal horn neurons in both intact and spinalized rats.

The effects of immersing a hindpaw in 60 degrees C water for 15 s on spontaneous and pinch-evoked activity recorded from 77 convergent neurons in the contralateral lumbar enlargement were examined. Cells were recorded from intact rats anesthetized with either ketamine or pentobarbital, or in rats that were decerebrated-intact or decerebrated-spinalized to determine if the heterotopic modulation was altered under these different conditions. In 47 neurons with background firing, immersion of the contralateral hindpaw inhibited the on-going activity in 6 of 19 cells recorded from ketamine anesthetized rats, 4 of 12 from pentobarbital anesthetized rats, 7 of 12 from decerebrate-spinalized rats, and 0 of 4 from decerebrate-intact rats. However, this inhibition was variable, both between and within neurons, because not every convergent neuron was inhibited, and there were trials in which immersion had no effect on the on-going activity of a neuron that had been previously inhibited by identical stimulation. In all 77 neurons, across all groups, discharges evoked by pinching the ipsilateral hindpaw were unaffected by contralateral immersion, even in cells where on-going activity was inhibited. Immersion of a hindpaw inhibited on-going, but not evoked, activity of contralateral convergent neurons. This inhibition was observed in rats under varied anesthetic conditions and in spinalized and intact rats. However, not all convergent neurons were inhibited by the remote stimulation even in intact rats, an observation inconsistent with the DNIC model of supraspinally mediated heterotopic modulation. This indicates that the effect of remote noxious stimulation in intact animals is not, under every experimental condition, a widespread inhibition of all convergent neurons.

Animals↗