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Results for “Immersion”

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At least 145 records · Page 8Linked to original sources

PubMed2006

Spinal cord transection inhibits HR reduction in anesthetized rats immersed in an artificial CO2-hot spring bath.

Like humans, the heart rate (HR) of anesthetized rats immersed in CO(2)-water is lower than that when immersed in tap water at the same temperature. To investigate the afferent signal pathway in the mechanism of HR reduction, Wistar rats were anesthetized with urethane and then the spinal cord was transected between T(4) and T(5). The animals were immersed up to the axilla in a bathtub of tap-water (CO(2) contents: 10-20 mg.l(-1)) or of CO(2)-water (965-1,400 mg.l(-1)) at 35 degrees C while recording HR, arterial blood pressure, and arterial blood gas parameters (PaCO(2), PaO(2), pH). Arterial blood gas parameters did not change during immersion, irrespective of CO(2) concentration of the bath water, whereas the HR was reduced in the CO(2)-water bath. The inhalation of CO(2)-mixed gas (5% CO(2), 20% O(2), 75% N(2)) resulted in increased levels of blood gases and an increased HR during immersion in all types of water tested. The HR reduction observed in sham transected control animals immersed in CO(2)-water disappeared after subsequent spinal cord transection. These results show that the dominant afferent signal pathway to the brain, which is involved in inducing the reduced HR during immersion in CO(2)-water, is located in the neuronal route and not in the bloodstream.

Animals↗

PubMed2000

Flow cytometry analysis of the effects of pre-immersion on the biocompatibility of glass-reinforced hydroxyapatite plasma-sprayed coatings.

Multilayered coatings composed of mixtures of HA and P2O5-based bioactive glasses are of potential clinical benefit in orthopaedic and dental surgery. Pre-immersion of these materials has been reported to further enhance their efficacy in vivo, although the precise biological effects of this treatment are not yet known. In this study we have therefore prepared double-layer plasma-sprayed coatings and evaluated the effects of pre-immersion on the growth and function of human osteosarcoma cells in vitro, using the MTT assay and flow cytometry analysis, respectively. The results showed that the increase in numbers of viable cells was the same or elevated following incubation on the pre-immersed HA and glass-reinforced HA coatings compared with the non-immersed materials. In addition, the expression of bone sialoprotein and fibronectin, two key connective tissue antigens, was up-regulated in cultures grown on the pre-immersed surfaces compared with the non-treated materials. Moreover, cell numbers and antigen expression both improved as the proportion of glass increased, particularly in the pre-immersed samples. Our findings thus suggest that the immersion treatment of these materials appeared to improve the response of these bone-like cells.

Biocompatible Materials↗

PubMed2002

A new high-aperture glycerol immersion objective lens and its application to 3D-fluorescence microscopy.

High-resolution light microscopy of glycerol-mounted biological specimens is performed almost exclusively with oil immersion lenses. The reason is that the index of refraction of the oil and the cover slip of approximately 1.51 is close to that of approximately 1.45 of the glycerol mountant, so that refractive index mismatch-induced spherical aberrations are tolerable to some extent. Here we report the application of novel cover glass-corrected glycerol immersion lenses of high numerical aperture (NA) and the avoidance of these aberrations. The new lenses feature a semi-aperture angle of 68.5 degrees, which is slightly larger than that of the diffraction-limited 1.4 NA oil immersion lenses. The glycerol lenses are corrected for a quartz cover glass of 220 microm thickness and for a 80% glycerol-water immersion solution. Featuring an aberration correction collar, the lens can adapt to glycerol concentrations ranging between 72% and 88%, to slight variations of the temperature, and to the cover glass thickness. As the refractive index mismatch-induced aberrations are particularly important to quantitative confocal fluorescence microscopy, we investigated the axial sectioning ability and the axial chromatic aberrations in such a microscope as well as the image brightness as a function of the penetration depth. Whereas there is a significant decrease in image brightness associated with oil immersion, this decrease is absent with the glycerol immersion system. In addition, we show directly the compression of the optic axis in the case of oil immersion and its absence in the glycerol system. The unique advantages of these new lenses in high-resolution microscopy with two coherently used opposing lenses, such as 4 Pi-microscopy, are discussed.

Animals↗

PubMed1997

Immersion in antibiotic solution prevents bacterial adhesion onto biodegradable prostatic stents.

OBJECTIVE: To determine whether immersion in antibiotic solution reduces or prevents bacterial adhesion onto biodegradable prostatic stents. MATERIALS AND METHODS: Pre-cut segments of polyglycolic acid (PGA) and polylactic acid (PLA) prostatic stents were incubated with two common uropathogenic bacterial strains (Enterococcus faecalis and Escherichia coli) with and without previous immersion in antibiotic solution. Tobramycin, ceftriaxone and ciprofloxacin solutions were used, as these antibiotics are commonly administered for the prophylaxis and treatment of urinary tract infection (UTI). RESULTS: Immersion in ciprofloxacin solution prevented the adherence of both bacterial strains. Immersion in ceftriaxone solution prevented only the adherence of the E. coli strain. Immersion in tobramycin solution had no effect on either of the strains. The stent materials per se did not influence bacterial adhesion. After immersion in ciprofloxacin, the stent segments retained significant antibacterial activity even after one day's incubation in saline. CONCLUSION: Immersion in a suitable antibiotic solution may significantly reduce and even prevent bacterial adhesion onto biodegradable prostatic stents. Preventing bacterial adhesion may reduce the risk of UTI during the use of these devices.

Anti-Bacterial Agents↗

PubMed2001

Water immersion stress prevents caerulein-induced pancreatic acinar cell nf-kappa b activation by attenuating caerulein-induced intracellular Ca2+ changes.

Prior stress ameliorates caerulein-induced pancreatitis in rats. NF-kappaB is a proinflammatory transcription factor activated during caerulein pancreatitis. However, the effects of prior stress on pancreatic NF-kappaB activation are unknown. In the current study, the effect of prior water immersion stress on caerulein and tumor necrosis factor-alpha (TNF-alpha)-induced NF-kappaB activation in the pancreas was evaluated. Water immersion of rats for up to 6 h prevents supramaximal caerulein-induced pancreatic IkappaB-alpha degradation and NF-kappaB activation in vivo. NF-kappaB activity is also inhibited in vitro in pancreatic acini prepared from water-immersed animals. TNF-alpha-induced NF-kappaB activation in pancreas or in pancreatic acini is unaffected by prior water immersion. Chelation of intracellular Ca(2+) by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate/acetoxymethyl ester has similar effects to water immersion in preventing caerulein but not TNF-alpha-induced NF-kappaB activation in pancreas. Both the spike response and the sustained rise in [Ca(2+)](i) in response to supramaximal caerulein stimulation are reduced markedly in acini prepared from water-immersed animals as compared with normal animals. Our findings indicate that, in addition to Ca(2+)-dependent mechanisms, Ca(2+)-independent signaling events also may lead to NF-kappaB activation in pancreatic acinar cells. Water immersion stress prevents supramaximal caerulein-induced NF-kappaB activation in pancreas in vivo and in vitro by affecting intracellular Ca(2+) homeostasis.

Animals↗

PubMed2004

Influence of waterproof covering on finger skin temperature and hand pain during immersion test for diagnosing hand-arm vibration syndrome.

The purpose of this study was to examine the influence of waterproof covering on finger skin temperature (FST) and hand pain during immersion test for diagnosing hand-arm vibration syndrome complying with the proposal of the International Organization for Standardization (ISO/ CD14835-1, 2001) for measurement procedure. Six healthy male subjects took part in the immersion tests and immersed their both hands into water at 12 degrees C for 5 min, repeatedly with two types of waterproof covering (polyethylene and natural rubber gloves) or without hand covering (bare hands) during immersion. The FST data from middle fingers and subjective pain scores for hand pain were analyzed. Statistically significant differences in FST among three conditions were observed showing the highest FST with natural rubber gloves, followed by the FST with polyethylene gloves and the lowest with bare hands. Significant differences in pain score among three conditions were observed during immersion showing the lowest pain score with natural rubber gloves, followed by the pain score with polyethylene gloves and the highest with bare hands. Immersion test with polyethylene gloves instead of bare hands during immersion seems to be suitable for reducing subject suffering.

Analysis of Variance↗

PubMed2002

Microbial profile and antibiotic susceptibility of Campylobacter spp. and Salmonella spp. in broilers processed in air-chilled and immersion-chilled environments.

Carcass chilling is considered a critical step for inhibiting bacterial growth during poultry processing. The objective of this study was to compare microbiological loads and the incidence of Salmonella spp. and Campylobacter spp. on broiler carcasses subjected to immersion chilling and air chilling. Additionally, the antibiotic resistance patterns of pathogen isolates were determined. The results of this study indicated that the incidence of Salmonella spp. and Campylobacter spp. tends to be significantly lower in air-chilled broilers, suggesting that cross-contamination may be more prevalent for immersion-chilled broilers. No significant differences were detected between chilling treatments for total aerobic populations or for generic E. coli or coliform counts. Psychrotrophic populations were significantly larger (P < 0.05) in immersion-chilled broilers than in their air-chilled counterparts. Campylobacter isolates from immersion-chilled broilers had a higher incidence of resistance to nalidixic acid (NAL) and related fluoroquinolones than isolates from air-chilled broilers did. Additionally, Campylobacter isolates from air-chilled broilers had a higher frequency of resistance to tetracycline than isolates from immersion-chilled broilers did. With regard to Salmonella, isolates from immersion-chilled broilers had a higher incidence of resistance to NAL than isolates from air-chilled samples did. No Salmonella isolates from immersion- or air-chilled broilers were resistant to the fluoroquinolones tested. The chilling method used during processing may influence the microbial profile of postchilled broilers.

Adaptation, Physiological↗

PubMed2005

Surgical treatment for rabbits' femoral arteries subjected to gunshot wounds combining with seawater immersion.

OBJECTIVE: To investigate the surgical treatment methods and evaluate the outcome of gunshot wounds combining with seawater immersion in rabbits' femoral arteries. METHODS: One hundred healthy New Zealand white rabbits (either sex, 3.14 kg+/-0.61 kg in weight) were randomly divided into a seawater immersion group (n=50) and a simple injury group (n=50). The unilateral femoral arteries of all the rabbits were injured by 0.38 g steel spheres with velocity of 600-800 m/s fired by a 7.62 mm rifle. The rabbits in the seawater immersion group were immersed in seawater (saline content of 2.54%, pH 8.2-8.4, and at 21 degrees C) for 60 minutes but those in the simple injury group were not. After the injured segment (observed by naked eyes) of the femoral artery was excised, the blood flow restoration was reconstructed by direct end-to-end anastomosis, reversed autogenous venous grafting or cryopreserved arterial allografting, according to the length of the arterial defects. At 24 hours, and 7, 14 and 21 days after operation, the blood flow was examined. Operative exploration was performed for the animals with partly or fully obstructed blood flow. The tissues around the anastomosis sites and the grafts were harvested for pathological observation under a light microscope and an electron microscope. RESULTS: In the rabbits with completely transected injury, the unobstructed rates in the first 3 weeks after operation were 80.00% in the seawater immersion group and 86.67% in the single injury group, and no significant difference was found between the two groups (P>0.1). In the rabbits with arterial contusion injury, the unobstructed rates in the first 3 weeks after operation were 86.67% in the seawater immersion group and 82.35% in the single injury group, and no significant difference was found between the two groups (P>0.1). Most thrombosis occurred in the first operative week. Atypical endothelial cells were detected at the anastomosis sites at the first operative week, and the anastomosis sites were lined with endothelial cells in 3 weeks postoperatively. CONCLUSIONS: During the surgical treatment for gunshot wounds combining with seawater immersion, resection of the grossly-injured artery and routine artery reconstruction can obtain satisfactory outcome. Homologous artery is a kind of vascular graft with certain applied value.

Animals↗

PubMed1996

The efficacy of hyoscine hydrobromide in reducing side-effects induced during immersion in virtual reality.

BACKGROUND: Regan and Price (1994) investigated the frequency of occurrence and severity of side-effects of using an immersion virtual reality system in 150 subjects: 61% of the subjects reported symptoms of malaise at some point during a 20-min immersion and 10-min post-immersion period. This paper describes a double-blind placebo-controlled study that investigated whether 300 microgram of hyoscine/scopolamine hydrobromide administered to subjects prior to immersion in virtual reality was effective in reducing side-effects experienced during immersion. HYPOTHESIS: It was hypothesized that the hyoscine hydrobromide would cause a significant reduction in reported symptoms. METHODS: We administered 300 micrograms of hyoscine hydrobromide to 19 subjects, and 20 subjects were administered a placebo compound 40 min prior to a 20-min immersion in VR. Data on malaise were collected using a simulator sickness questionnaire and a malaise scale. RESULTS: A 2 x 2 Chi-square analysis comparing the numbers of subjects reporting no symptoms on the malaise scale with those reporting some symptoms in the placebo and hyoscine conditions showed the differences between the two groups to be statistically significant at the 0.01 level (Chi-square = 7.392 with 1 df, p = 0.007). This difference was clearly in the direction of fewer symptoms being reported in the hyoscine condition. CONCLUSIONS: The results of the study showed that the hyoscine was effective in reducing symptoms that are commonly observed during immersion in virtual reality.

Antiemetics↗

PubMed1996

Mechanical and electrical changes in human muscle after dry immersion.

The effects of a 7-day dry immersion, with the body protected from contact with the water, were investigated in six subjects. Changes in contraction properties were studied in the triceps surae muscle. After immersion, the maximal voluntary contraction (MVC) was reduced by 33.8% (P < 0.01), and the electrically evoked maximal tetanic contraction (Po) was reduced by 8.2% (P > 0.05). The difference between Po and MVC expressed as a percentage of Po and referred to as force deficiency was also calculated. The force deficiency increased by a mean of 44.1% (P < 0.01) after immersion. The decrease in Po was associated with increased maximal rates of tension development (7.2%) and of tension relaxation. The twitch time to peak was not significantly changed, and half relaxation and total contraction time were decreased by 5.3% and 2.8%, respectively, but the twitch tension (Pt) was not significantly changed and the Pt:Po ratio was decreased by 8.7% after immersion. The muscle surface action potential showed an increase in duration (18.8%) and decreases in amplitude and total area (14.6% and 2.8%; P < 0.05-0.01, respectively). Comparison of the electrical and mechanical alterations recorded during the voluntary contractions, and in the contractions evoked by electrical stimulation of the motor nerve, would suggest that immersion not only modified the peripheral processes associated with contraction, but also changed the central and/or neural command of the contraction. At peripheral sites, it is proposed that the intracellular processes of contraction played a role in the contractile impairment recorded during immersion.

Action Potentials↗

PubMed1996

Change in sympathetic activity, cardiovascular functions and plasma hormone concentrations due to cold water immersion in men.

The purpose of this study was to determine whether or not repeated short-term cold water immersions can induce a change in the activity of the sympathetic nervous system and, consequently, in cardiovascular functions in healthy young athletes. Changes in some plasma hormone concentrations were also followed. A single cold water immersion (head-out, at 14 degrees C, for 1 h) increased sympathetic nervous system activity, as evidenced by a four-fold increase (P < 0.05) in plasma noradrenaline concentration. Plasma adrenaline and dopamine concentrations were not increased significantly. Plasma renin-angiotensin activity was reduced by half (P < 0.05) during immersion but plasma aldosterone concentration was unchanged. Stimulation of the sympathetic nervous system during immersion did not induce significant changes in heart rate, but induced peripheral vasoconstriction (as judged from a decrease in skin temperature) and a small increase (by 10%) in systolic and diastolic blood pressures. No clear change in reactivity of the sympathetic nervous system was observed due to repeated cold water immersions (three times a week, for 6 weeks). Neither the plasma renin-angiotensin activity, aldosterone concentration nor cardiovascular parameters were significantly influenced by repeated cold water immersions. A lowered diastolic pressure and an increase in peripheral vasoconstriction were observed after cold acclimation, however. Evidently, the repeated cold stimuli were not sufficient to induce significant adaptational changes in sympathetic activity and hormone production.

Acclimatization↗

PubMed1992

The relationship between maximum breath hold time in air and the ventilatory responses to immersion in cold water.

Eight subjects performed maximum breath holds in air and naked head-out immersions of 2 min duration in stirred water at 5, 10 and 15 degrees C. Analysis of the respiratory data collected in air and on immersion revealed a significant (P less than 0.05) inverse relationship between the maximum breath hold time (tbh,max) of subjects in air and their frequency of breathing and inspiratory volumes on immersion. No such relationship was identified between tbh,max in air and tidal volumes on immersion. It is concluded that the tbh,max of individuals in air may provide an indication of the magnitude of some of their respiratory responses to immersion. This information may be of use when personnel are being selected for activities with a high risk of immersion in cold water.

Adult↗

PubMed1990

The effects of immersion and exercise on prolactin during pregnancy.

Prolactin is an important hormone during pregnancy, affecting mother, fetus, and amniotic fluid volume. Immersion is known to affect prolactin levels significantly. To determine the effect of immersion and exercise on the prolactin response during pregnancy, we examined serum prolactin levels at 15, 25, and 35 weeks' gestation and 10 weeks post partum. Twelve women completed 20 min land rest, 20 min immersion in 30 degrees C water to the xiphoid, and 20 min exercise in the water at 60% VO2max. Resting prolactin levels were 1.91 +/- 0.32, 4.55 +/- 0.5, and 5.85 +/- 0.27 nmol.l-1 +/- standard error of the mean at 15, 25, and 35 weeks' gestation, respectively. Postpartum lactating women had a resting mean prolactin level of 3.95 +/- 1.6 versus 0.22 +/- 0.4 nmol.l-1 in non-lactating women. Prolactin levels declined significantly during immersion even after correction for dilution by plasma volume shifts. The immersion response was inversely related to the duration of pregnancy with 29%, 22%, and 12% drops during 15-, 25- and 35-week trials, respectively. Compared to rest, exercise prolactin levels remained depressed during the 15th and 25th week trials. We hypothesize that immersion in water caused prolactin levels to decline.

Adult↗

PubMed1979

Influence of immersion to the neck in water on airway closure and distribution of perfusion in man.

We measured closing volume (CV), expiratory reserve volume (ERV) regional distribution of lung volume (Vr) and perfusion in 7 normal subjects in air and during immersion to the neck in water. In four subjects immersion resulted in a CV greater than ERV and the normal perfusion distribution became inverted. In the other subjects, ERV remained larger than CV and perfusion distribution during immersion was uniform, not inverted. In 5 subjects closing volume increased and in 3 of them, the ratio of apical/basal Vr increased significantly during immersion. One subject had nomeasurable CV and in the other it was not measured. The data suggest: (1) that when CV is greater than ERV during immersion there is an inversion of the normal perfusion distribution, caused by hypoxia and/or an increase in mean alveolar pressure in the alveoli beyond the closed airways, and (2) that an increase in pleural pressure gradient during immersion may contribute to the increase in C.V.

Adolescent↗

PubMed2004

Reliability of the "immersion technique" during routine upper endoscopy for detection of abnormalities of duodenal villi in patients with dyspepsia.

BACKGROUND: Upper endoscopy is not routinely performed to directly detect abnormalities of the duodenal villi. The reliability of the immersion technique for assessment of duodenal villi was evaluated in a series of patients with dyspepsia. METHODS: A total of 396 patients who were to undergo standard EGD for dyspeptic symptoms were enrolled. Patients with suspected malabsorption were excluded. By performing a "modified immersion technique," duodenal villi were scored as the following: definitely present, partially present, or definitely absent. Three duodenal biopsy specimens were obtained from each patient, and villi also were scored histologically as the following: normal, partial villous pattern, or total villous atrophy. RESULTS: Sensitivity, specificity, and positive and negative predictive values of the modified immersion technique for detection of total villous atrophy were 100%, 99.7%, 85.7%, and 100%, respectively. Sensitivity, specificity, and positive and negative predictive values of modified immersion technique for detection of partial villous patterns were 75%, 99.5%, 60%, and 99.7%, respectively. Sensitivity, specificity, and positive and negative predictive values for modified immersion technique detection of any villous abnormality (partial or total villous atrophy) were 90.9%, 99.5%, 83.3%, and 99.7%, respectively. CONCLUSIONS: During standard EGD, duodenal evaluation by modified immersion technique can reliably detect abnormalities of duodenal villi. This simple diagnostic technique may be performed routinely during endoscopic exploration of duodenum.

Atrophy↗

PubMed1999

Edema of pregnancy: a comparison of water aerobics and static immersion.

OBJECTIVE: To compare the edema-relieving effects of static immersion with water aerobics. METHODS: Eighteen healthy women between 20 and 33 weeks' gestation were studied standing on land, immersed to the axilla, and participating in a water aerobics class, each for 30 minutes. RESULTS: Water aerobics and the static immersion led to a similar diuresis, 187 and 180 mL, respectively. Both were significantly greater than standing 30 minutes on land, 65 mL (P < .01). The dilutional effect as measured by a decline in urine specific gravity was also similar between static immersion and water aerobics and greater than standing on land (P < .01). Standing on land led to a small increase in leg volume compared with water aerobics or static immersion (P < .01). CONCLUSION: Water aerobics had diuretic and edema-relieving effects similar to static immersion. When women develop edema of pregnancy, water aerobics classes may be used as a potential treatment.

Adult↗

PubMed2001

Structure and immersion behavior of plasma-sprayed apatite-matrix coatings.

The microstructure and properties of a series of plasma-sprayed coatings from sinter-granulated powders fabricated from SiO2, CaO, P2O5 and Na2O-containing HA composite powders on Ti-6Al-4V substrate were reported. The immersion behavior of these coatings in a simulated body fluid (SBF) was also investigated. The results showed that sinter-granulated apatite-matrix powders were irregularly shaped and appeared quite similar. XRD patterns showed that during fabrication of the powders, P2O5 and SiO2 enhanced the decomposition of HA structure, while CaO and Na2O did not. Reasonably high bond strengths (45-50 MPa) were obtained from all coatings. The plasma spray process itself enhanced the decomposition of apatite and chemical reactions among different phases. When immersed in SBF, the intensities of such phases as alpha- and beta-TCP in all coatings decreased with immersion time and an apatite precipitation took place on all coating surfaces. The immersed SiO2- and CaO-containing HA (HSC) coating had the highest rate of apatite precipitation among all coatings. The variations in calcium ion concentration in simulated body fluid indicated that the HSC-immersed solution reached its maximal Ca concentration the earliest, while the HSCP (HA, SiO2, CaO and P2O5)-immersed solution reached its maximum the latest.

Apatites↗

PubMed1987

Cardiovascular responses to face immersion (the diving reflex) in human beings after alcohol consumption.

The diving reflex is a complex cardiovascular-respiratory response to immersion. This multireflex response in animals consists of apnea; bradycardia (the experimental parameter most often measured); peripheral vasoconstriction (resulting in preferential perfusion of the brain and heart); decreased cardiac output (with a maintained or increased stroke volume); and an increase in mean arterial blood pressure. These cardiovascular alterations act in a manner that conserves oxygen for the heart and brain. Because alcohol is often involved in water accidents with associated submersions, these initial experiments dealt with human volunteers who consumed alcohol to a blood level of 0.1 g% (legal level of intoxication). The diving reflex was elicited before and after alcohol consumption. Heart rate, blood pressure, and cardiac output were measured before, during, and after face immersion in 4 C water. In the sober state, immersion decreased heart rate, increased stroke volume, increased blood pressure, and increased total peripheral resistance. In comparison to the sober state, alcohol consumption increased pre-immersion heart rate, but did not significantly alter pre-immersion blood pressure or stroke volume. Following alcohol consumption, facial immersion decreased heart rate, but not to the same low rate as in the sober state. Alcohol consumption also evoked a lesser increase in blood pressure and failed to increase stroke volume significantly.

Adult↗