Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Immersion”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed1990

[Study on disintegration of glass ionomer cements. Effect of the starting time of immersion on the dissolution of Ca, Al and Si].

The disintegration of glass ionomer cements was evaluated with referred to the amounts of component elements of powders dissolved into solutions at various starting times of immersion. Glass ionomer cement products, three for luting and three for filling, were used. The starting times of immersion in solutions were; setting time and 10, 30 and 60 minutes and 24 hours after start of mixing. After the immersion in 30 ml of distilled water and physiological saline solution for 1 week, these solutions were analyzed by an atomic absorption spectrophotometer to determine the amounts of Ca, Al and Si. The amount of each element dissolved was highest when immersion in the solutions was started at the setting time except for Ca dissolved in physiological saline solution, and it tended to decrease as the start of immersion in the solutions was delayed. Some products contained Sr instead of Ca. The results indicated that glass ionomer cement should be protected from exposure to oral fluids for about 30 minutes in clinical use.

Glass Ionomer Cements↗
PubMed1990

Lack of diurnal effects on periodic exercise during prolonged cold water immersion.

Diurnal effects on periodic exercise were examined in 8 male divers wearing passive thermal protection during whole body immersions in 5 degrees C water for periods of up to 6 h. Studies were done during the course of 5-day air saturation dives at a depth of 1.61 ATA, with immersions beginning at 1000 h (AM) and 2200 h (PM). During each hour of immersion, leg exercise was done for 3 min each at workloads of 50, 70, and 90 W. Heart rate (HR) at each workload increased uniformly with immersion time, without a change in slope of HR vs. workload. No AM or PM differences occurred. AM resting VO2 increased linearly, and to the same extent as PM, with exposure time. VO2 at 50 W also increased at the same rate as resting values. VO2 at 70 and 90 W were similar for AM and PM and did not vary significantly during the 6-h immersions. Temporal increases in exercise HR may reflect cardiac compensation of diminished plasma volume. Workloads greater than or equal to 70 W generate enough metabolic heat in this specific condition to meet the thermogenic requirement. Lack of diurnal effects on exercise variables may be due to environmental conditions suppressing circadian rhythms.

Adult↗
PubMed1987

[Hormonal, beta-endorphin and renin activity changes in man during partial immersion, as a therapeutic method, in water at 38 degrees C].

This research was carried out to define the effects on men of head-out water immersion in a bath at 38.41 +/- 0.04 degrees C (mean +/- S.E.) with a method similar to that used for therapeutical rehabilitation and time of immersion of 30 minutes. Beta-endorphin, renin activity, aldosterone, cortisol, HGH, FSH, LH, TSH, T3, T4 and prolactin haematic levels were analysed. Seventeen healthy subjects (fourteen males and three females), aged 21-65 years (mean age 29.8 +/- 2.6) were studied. Water immersion caused a decrease in FSH and LH haematic concentrations; no significant changes occurred in beta-endorphin, renin activity, aldosterone, prolactin, cortisol, HGH, TSH, T3, T4 and FTI values. Thirty minutes after the end of immersion, FSH and LH levels returned to pre-immersion values. The probable pathogenesis of these observations is suggested.

Adult↗
PubMed1994

The frequency of occurrence and severity of side-effects of immersion virtual reality.

Virtual reality (VR) has become increasingly well-known over the last few years. However, little is known about the side-effects of prolonged immersion in VR. This study set out to investigate the frequency of occurrence and severity of side-effects of using an immersion VR system. Out of 146 subjects, 61% reported symptoms of malaise at some point during a 20-min immersion and 10-min post-immersion period. These ranged from symptoms such as dizziness, stomach awareness, headaches, eyestrain and lightheadedness to severe nausea. These symptoms caused 5% of the subjects to withdraw from the experiment before completing their 20-min immersion period. Further research needs to be conducted that attempts to identify those factors that play a causative role in the side-effects of the VR system, and that looks for methods of reducing these side-effects.

Aerospace Medicine↗
PubMed1998

Mechanical modifications to human pericardium after a brief immersion in 0.625% glutaraldehyde.

BACKGROUND AND AIMS OF THE STUDY: The use of human pericardium pretreated for 10 min with 0.625% glutaraldehyde (GLUT) in valvular repair or intracardiac reconstruction has produced good results. However, to date, no investigations have been made to determine the mechanical changes that occur in the tissue following such pretreatment. METHODS: Human pericardial samples were harvested from 25 patients and immersed in GLUT for increasing times (5, 10, 30, 60 min and 6 months). Either untreated human pericardium or bovine pericardium treated for six months with GLUT served as controls. Tensile tests were performed with a uniaxial load machine and a pulsative bench. Fatigue testing was for 14 days; each sample was tested at 1,200 cycles/min at a controlled pressure of 90-120 mmHg. RESULTS: Untreated tissue thickness was 0.44+/-0.16 mm, but after six months GLUT treatment it was 0.53+/-0.15 mm (p<0.001). There was a 13.7% shrinkage of tissue after six months immersion. Strain was significantly greater in treated tissue than in untreated tissue, while stiffness decreased with the duration of GLUT immersion. Young's modulus was significantly lower after six months GLUT treatment (0.26+/-0.06 MPa) compared with untreated, and 5-, 10- and 30-min GLUT treatment (0.32+/-0.15, 0.35+/-0.09, 0.32+/-0.09 and 0.36+/-0.10 MPa (p<0.05)), respectively. Creep was greater after six months GLUT treatment (0.5+/-0.03%) than in untreated and 10-, 30- and 60-min treatments (0.3+/-0.50, 0.27+/-0.01, 0.27+/-0.02, 0.3+/-0.01% (p<0.05)), respectively. Ultimate tensile stress (UTS) was greater in 10-min treated pericardium than in untreated tissue: 38.46+/-11.75 versus 22.17+/-8.30 MPa (p<0.05) respectively. Strain at rupture was greater in the 6-month group (30.62+/-2.54%) than for untreated and 10-, 30- and 60-min GLUT immersion 16.3+/-0.73, 21.85+/-0.75, 20.12+/-1.04 and 18.87+/-0.86% (p<0.05), respectively. Fatigue testing showed an increased length after five and 10 min, and six months, with a lengthening of 14.66, 12.53, 7.66%, respectively compared with 3.5% for untreated tissue (p<0.05). There were three failures in the untreated group (n = 5), none in the 5- and 10-min groups, and one in the 6-month group (p<0.05). CONCLUSION: Brief immersion of human pericardial tissue in 0.625% glutaraldehyde reduces the tissue's stiffness and improves its durability for use in cardiac surgery.

Biomechanical Phenomena↗
PubMed2004

Apatite formation on the surface of wollastonite/tricalcium phosphate composite immersed in simulated body fluid.

Wollastonite/tricalcium phosphate composites were prepared and immersed in SBF for various periods to investigate the apatite-formation mechanism on their surfaces. Surface morphologies and composition before and after immersion were analyzed by SEM and EDS technologies. The concentration changes of calcium, silicon, and phosphorus in SBF due to the immersion of the samples were measured with inductively coupled plasma atomic emission spectroscopy, and the corresponding pH values in SBF were recorded. XRD and IR were used to examine the changes in crystalline phases and functional groups. It was found that, after immersion for 1 day, the samples were covered by pom-pom-like apatite granules, resulting from the dissolution of wollastonite and the simultaneous transformation of TCP. This quickly led to the subsequent precipitation of another apatite layer, which covered the earlier-formed surface completely. These results indicate that the wollastonite/tricalcium phosphate composite is a potential biomaterial candidate because of its high bioactivity and in situ porous structure.

Apatites↗
PubMed1993

Renal response to head-out water immersion in Korean women divers.

Head-out water immersion (HOI) induces a profound diuresis and natriuresis, which may endanger the body fluid balance of breath-hold divers during prolonged diving work. To investigate if adaptation is acquired by professional breath-hold divers, we have evaluated renal responses to 3-h HOI in 5 Korean women divers (Amas) and 11 nondiving housewives (controls). In both control and diver groups, the average urine flow during 3-h immersion was four times greater and Na+ excretion was 70%-80% greater than the pre-immersion value [urine flow: 3.7 (SD 1.0) ml.min-1 vs 0.9 (SD 0.4), P < 0.001, in controls; 4.3 (SD 0.9) vs 1.1 (SD 0.4), P < 0.001, in divers; Na+ excretion: 270 (SD 176) mumol.min-1 vs 161 (SD 84), P < 0.025, in controls; 303 (SD 31) vs 164 (SD 62), P < 0.005, in divers]. In all cases, the values for a given period were not significantly different between the two groups. The plasma concentrations of Na+ and osmolality, and renal clearance of creatinine did not change significantly. However, the osmolal clearance increased [from 2.0 (SD 0.8) ml.min-1 to 2.8 (SD 0.7), P < 0.05, in the controls; from 2.2 (SD 0.4) to 2.6 (SD 0.4), P < 0.05, in the divers] and free water clearance changed from negative to positive values [from -1.1 (SD 0.5) ml.min-1 to 1.2 (SD 0.3), P < 0.005, in the controls; from -1.2 (SD 0.4) to 1.6 (SD 1.1), P < 0.01, in the divers] during immersion, again the pattern of change being similar in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The role of posture on the changes in plasma atrial natriuretic factor and arginine vasopressin levels during immersion.

In seven healthy male volunteers we investigated changes in plasma atrial natriuretic factor [( ANF]), arginine vasopressin [( AVP]) and plasma volume (PV) during supine immersion. Twenty minutes head-out water immersion in a supine position in a thermo-neutral water bath attenuated the increase in PV induced by 20 min in a supine position in air, but increased the mean plasma [ANF] from 32.0 pg.ml-1, SEM 5.1 to 53.3 pg.ml-1, SEM 3.6 and decreased the mean plasma [AVP] from 1.4 pg.ml-1, SEM 0.1 to 0.9 pg.ml-1, SEM 0.04. Simultaneously, diuresis and natriuresis increased markedly. During a 20-min control period in the supine posture without immersion, PV, plasma [ANF] and [AVP] remained unaffected while diuresis and natriuresis did not increase to the same extent. These data suggest that an increase in the central blood volume induced by a weak external hydrostatic pressure during supine immersion triggered the changes in plasma [ANF] and [AVP] and that the increase was probably due to a shift of blood volume from peripheral to central vessels. The changes in plasma [ANF] contributed to the changes in natriuresis.

Adult↗
PubMed1976

Effect of physical fitness on vanillylmandelic acid excretion during immersion.

The effects of 4--6 h head-out immersion on excretion of vanillylmandelic acid (VMA), blood pressure and plasma volume were estimated in 8 endurance-trained (TR) and 8 untrained (UT) subjects. In the trained only a slight increase of VMA excretion occurred (4 h value: +2.7 +/- 10.9 ng/ml GFR), but there was a highly significant increase in the UT (+29.0 +/- 17.2 ng/ml GFR). VMA values during control experiments in supine position tended to decrease in both groups. Systolic and diastolic blood pressure fell by 20 mm Hg after beginning of immersion; in the UT plasma volume was reduced while it remained constant in TR. The results indicate that orthostatic intolerance (o.i.) after immersion is not effected by decreased sympathetic innervation of vessels; in contrast it seems to be partly compensated for by an elevated sympathetic activity at least in the UT. As a main cause for the post-immersion o.i. one might suggest a decrease in renin activity.

Adult↗
PubMed1986

Renal hemodynamics and natriuresis during water immersion in normal humans.

The renal vascular and functional responses to acute "central hypervolemia" by water immersion to the neck were determined in six normal subjects. During isotonic-isooncotic expansion by water immersion there was a significant increase in urine flow from 1.1 +/- 0.1 to 6.9 +/- 1.0 ml/min (p less than 0.05) and sodium excretion from 99.1 +/- 8.8 to 300 +/- 28 mu Eq/min (p less than 0.05). Glomerular filtration rate did not change while renal blood flow significantly increased during water immersion. Deep intrarenal venous pressure (IRVP) increased from 18.2 +/- 1.4 to 32 +/- 1.7 mmHg (p less than 0.05) while mean arterial pressure was unchanged. This marked natriuresis seen during water immersion was associated with reduced renal vascular resistance and increased deep intrarenal venous pressure demonstrating that continued natriuresis could relate to increased capillary hydrostatic pressure.

Adult↗
PubMed1991

Lung volume changes in response to altered breathing gas pressure during upright immersion.

Since elastic and flow-resistive respiratory work are volume dependent, changes in lung volume during immersion affect respiratory effort. This investigation examined changes in lung volume with air delivery pressure modifications during upright immersion. Static pressure-volume relaxation relationships and lung volumes were obtained from ten immersed subjects breathing air at four delivery pressures: mouth pressure, lung centroid pressure (PLC), and 0.98 kPa above and below PLC. The PLC is the static lung pressure which returns the respiratory relaxation volume (VR) to normal and was previously determined to be +1.33 kPa relative to pressure at the sternal notch. Lung volume changes observed when breathing air at mouth pressure were reversed when air was supplied at PLC. The expiratory reserve volume (ERV) and VR were reduced by 58% and 87%, respectively, during uncompensated immersion. These differences indicated an active defence of ERV and implied that additional static respiratory work was required to overcome transrespiratory pressure gradients.

Adult↗
PubMed1989

The increased oxygen uptake upon immersion. The raised external pressure could be a causative factor.

The principal cause of the immediate transient elevation in ventilation (VE, L.min-1) and oxygen uptake (VO2, L.min-1), when a human subject is immersed in cold water is considered to be the stimulation of cutaneous cold receptors. The present study demonstrates that the initial VE and VO2 responses are comprised of a thermogenic and a hydrostatic component. The peak values in VE reached (mean +/- SD) 66.8 +/- 22.3, 53.9 +/- 38.1, 32.2 +/- 15.4, 22.5 +/- 3.6, 19.5 +/- 4.6 L.min-1 during the first minute of immersion in 10 degrees, 15 degrees, 20 degrees, 28 degrees and 40 degrees C water, respectively. Similarly, peaks (mean +/- SD) in VO2 of 1.22 +/- 0.25, 1.01 +/- 0.32, 0.98 +/- 0.39, 0.81 +/- 0.09, and 0.78 +/- 0.26 L.O2.min-1, were reached when subjects were immersed in 10 degrees, 15 degrees, 20 degrees, 28 degrees, and 40 degrees C water. It is concluded that the observed increases in VO2 during the first minute of immersion are partly due to the increased hydrostatic pressure causing a shift of venous blood towards the thoracic region, and a transient increase in the uptake of oxygen into the blood.

Body Temperature↗
PubMed1991

Effects of water-immersion-induced stress and intraperitoneal administration of brain-gut peptides upon immunoreactive thyrotropin-releasing hormone and prostaglandin E2 concentrations in the rat stomach.

The effects of water-immersion-induced stress and intraperitoneal (i.p.) administration of selected neuropeptides on the levels of thyrotropin-releasing hormone (TRH) and prostaglandin E2 (PGE2) were studied in the rat stomach. Water-immersion caused a significant decrease immunoreactive-TRH (ir-TRH) concentrations in the stomach, and a significant increase in ir-TRH concentrations in the gastric juice. The concentrations of PGE2 were significantly increased at 0.5-4 hrs, and significantly decreased at 6-8 hrs after water-immersion. In the experiment of i.p. administration of selected neuropeptides, the level of ir-TRH in the stomach was significantly decreased after VIP injection, whereas it was significantly increased after beta-endorphin injection. The concentration of PGE2 was significantly decreased in the stomach after i.p. administration of TRH and VIP. However, it did not change after beta-endorphin injection. These results indicate that some neuropeptides may participate in regulating the endogenous level of PGE2 and that these interrelations between neuropeptides and PGE2 may be important as ulcerogenic factors in stress ulcers induced by water-immersion in the rat.

Animals↗
PubMed2004

Cold-water acclimation does not modify whole-body fluid regulation during subsequent cold-water immersion.

We investigated the impact of cold-water acclimation on whole-body fluid regulation using tracer-dilution methods to differentiate between the intracellular and extracellular fluid compartments. Seven euhydrated males [age 24.7 (8.7) years, mass 74.4 (6.4) kg, height 176.8 (7.8) cm, sum of eight skinfolds 107.4 (20.4) mm; mean (SD)] participated in a 14-day cold-water acclimation protocol, with 60-min resting cold-water stress tests [CWST; 18.1 (0.1) degrees C] on days 1, 8 and 15, and 90-min resting cold-water immersions [18.4 (0.4) degrees C] on intervening days. Subjects were immersed to the 4th intercostal space. Intracellular and extracellular fluid compartments, and plasma protein, electrolyte and hormone concentrations were investigated. During the first CWST, the intracellular fluid (5.5%) and plasma volumes were reduced (6.1%), while the interstitial fluid volume was simultaneously expanded (5.4%). This pattern was replicated on days 8 and 15, but did not differ significantly among test days. Acclimation did not produce significant changes in the pre-immersion distribution of total body water, or changes in plasma osmolality, total protein, electrolyte, atrial natriuretic peptide or aldosterone concentrations. Furthermore, a 14-day cold-water acclimation regimen did not elicit significant changes in body-fluid distribution, urine production, or the concentrations of plasma protein, electrolytes or the fluid-regulatory hormones. While acclimation trends were not evident, we have confirmed that fluid from extravascular cells is displaced into the interstitium during acute cold-water immersion, both before and after cold acclimation.

Acclimatization↗
PubMed1996

Changes in thermal homeostasis in humans due to repeated cold water immersions.

The purpose of this study was to monitor changes in body and skin temperatures, heat production, subjective shivering, cold sensation and body fat content in humans after intermittent cold water immersion. Repeated exposures of young sportsmen to cold water (head out, 14 degrees C, 1 h, 3 times per week for 4-6 weeks) induced changes in regulation of thermal homeostasis. "Cold acclimated" subjects exhibited an hypothermic type of adaptation. Central and peripheral body temperatures at rest and during cold immersion were lowered. The metabolic response to cold was delayed and subjective shivering was attenuated. The observed hypothermia was due to the shift of the threshold for induction of cold thermogenesis to lower body temperatures. "Cold acclimated" subjects also showed a lowered cold sensation. Because of the observed physiological changes, about 20% of the total heat production was saved during one cold water immersion of "cold acclimated" subjects. Maximal aerobic and anaerobic performances were not altered. No change in the thermosensitivity of the body temperature controller, as assessed from the unchanged slope of the relation between the deep body temperature and total heat production, was observed. Changes in cold sensation and regulation of cold thermogenesis were noticed first after four cold water immersions and persisted for at least 2 weeks after termination of the adaptation procedure. A trend towards a small increase in the body fat content was also observed. This finding, as well as the increased vasoconstriction, evidenced by the lowered skin temperature, indicate that slight changes in body insulation may also occur after "cold acclimation" in humans.

Acclimatization↗
PubMed2006

Effect of cilostazol, a selective type-III phosphodiesterase inhibitor, on water-immersion stress-induced gastric mucosal injury in rats.

BACKGROUND: Cilostazol, a specific type-III phosphodiesterase inhibitor, is widely used for the treatment of ischemic symptoms of peripheral vascular disease. Recent studies have reported that the mechanism of cilostazol is related to the suppression of pro-inflammatory cytokine production and improvement of local microcirculation disturbances. The pathogenesis of stress-induced gastric mucosal lesions is characterized by the activation of inflammatory cells and the production of inflammatory cytokines. The effects of cilostazol on the development of gastric mucosal lesions have not been reported. In the present study, we examined the effect of a cilostazol on water-immersion stress-induced gastric mucosal lesions. METHODS: Rats were subjected to water-immersion stress with or without pretreatment with a single intraperitoneal injection of the selective type-III phosphodiesterase inhibitor, cilostazol. We measured the gastric mucosal lesion and the concentrations of myeloperoxidase (MPO), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1), as an index of neutrophil accumulation and pro-inflammatory cytokine production. RESULTS: Cilostazol ameliorated the gastric mucosal injury induced by water-immersion stress (P<0.001). The gastric contents of MPO, TNF-alpha, IL-1beta, and CRO/CINC-1 were all increased after water-immersion stress and were reduced to almost normal levels by cilostazol. CONCLUSIONS: In this study, we demonstrated that a selective type-III phosphodiesterase inhibitor, cilostazol, inhibited stress-induced gastric inflammation and damage via suppressing the production of pro-inflammatory cytokines. Cilostazol may be useful for preventing gastric mucosal lesions.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2006

Paradoxical response to water immersion in replanted fingers.

When the fingers are immersed in water digital blood flow is reduced and the skin wrinkles, suggesting that vasoconstriction plays a role. However, is wrinkling due to sympathetic activation or some intrinsic property of the skin? To define the role of autonomic innervation in skin wrinkling we measured changes in blood perfusion (Laser Doppler Perfusion Imager) in 20 successfully replanted fingers (mean time after complete amputation 17.5 +/- 5.2 months). We compared responses in replanted fingers with those in corresponding contralateral normal fingers before and immediately after immersion in saline (0.5 mol/l NaCl at 40 degrees C). In the normal fingers, immersion caused a decrease in blood flow by 27.6 +/- 11.5% and skin wrinkling. However, in the replanted fingers blood flow increased by 22.8 +/- 19.6% and the skin did not wrinkle. The paradoxical cutaneous vasodilatation and absence of wrinkling in the denervated fingers suggests that sympathetic innervation is important in water-immersion skin wrinkling.

Adult↗
PubMed1992

Effect of incomplete immersion of the head in waterbath stunners on the effectiveness of electrical stunning in ducks.

Ten ducks were subjected to electrical stunning with their heads completely immersed in the water of a waterbath, and 10 ducks received the same current while only the bill and skin over the crop made contact with the water. The effect on visual evoked responses in the brain was examined. A higher proportion of birds had lost their visual evoked responses immediately following the current with whole head immersion. It is suggested that crop and bill immersion is less effective in disturbing brain function than whole head immersion.

Abattoirs↗