PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Cold Temperature”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 1,045 records · Page 58Linked to original sources
PubMed2003

Treatment of term infants with head cooling and mild systemic hypothermia (35.0 degrees C and 34.5 degrees C) after perinatal asphyxia.

OBJECTIVE: To assess the safety of selective head cooling in birth-asphyxiated term newborn infants while maintaining the rectal temperature at 35.0 degrees C or 34.5 degrees C. METHODS: Twenty-six term infants with Apgar <or=6 at 5 minutes or cord/first arterial pH <7.1, plus evidence of encephalopathy, were studied. After parental consent had been obtained, 13 infants received selective head cooling with the rectal temperature maintained at 35.0 degrees C in 6 infants and at 34.5 degrees C in 7 infants. The remaining 13 infants were normothermic. Cooling was achieved by circulating water at 10 degrees C through a cap placed around the head. Rectal, fontanelle, and nasopharyngeal temperatures were monitored. RESULTS: One cooled infant died 2 days after rewarming, and 3 control infants died. Seizures occurred in 9 (69%)of 13 cooled infants and 5 (38%) of 13 control infants. Respiratory support within the first 72 hours of life was required in 10 of 13 infants in both the cooled and control groups. Three cooled infants and 1 control infant received nitric oxide for persistent pulmonary hypertension. During the same interval, 6 of the cooled infants and 4 of the control infants had episodes in which their blood pressure fell to <40 mm Hg; in 2 infants in each group, the lowest blood pressure was below 35 mm Hg. No requirement for volume expansion or increased inotropic support was seen in any infant during stepwise rewarming. All of the cooled infants demonstrated a fall in heart rate during cooling, but the rate was <80/min in only 2 cases and no infant had a rate <70/min. No infant demonstrated an abnormal rhythm or was clinically compromised by the change in heart rate. One infant cooled to a rectal temperature of 34.5 degrees C had a prolonged QT interval of 570 ms associated with a heart rate of 85/min on electrocardiogram aged 34 hours. This returned to normal after rewarming. Platelet counts below 150 x 10(9)/L, hypoglycemia below 2.6 mmol/L, and highest creatinine were not statistically different between cooled and control infants. Positive precooling blood cultures were found in 1 cooled and 1 control infant. The mean cap water input temperature used during cooling was 10 +/- 1 degrees C. During active cooling, the mean difference between rectal and nasopharyngeal temperature was 1.4 degrees C in the infants who were not receiving respiratory support, but this gradient could not be measured in those who were receiving respiratory support that involved delivery of warmed gases to the nasopharynx. CONCLUSIONS: This study suggests that selective head cooling combined with mild systemic hypothermia of 34.4 degrees C or 35.0 degrees C is a stable, well-tolerated method of reducing cerebral temperature in term newborn infants after perinatal asphyxia.

Anticonvulsants↗
PubMed2003

Ultraviolet radiation and the snow alga Chlamydomonas nivalis (Bauer) Wille.

Aplanospores of Chlamydomonas nivalis are frequently found in high-altitude, persistent snowfields where they are photosynthetically active despite cold temperatures and high levels of visible and ultraviolet (UV) radiation. The goals of this work were to characterize the UV environment of the cells in the snow and to investigate the existence and localization of screening compounds that might prevent UV damage. UV irradiance decreased precipitously in snow, with UV radiation of wavelengths 280-315 nm and UV radiation of wavelengths 315-400 nm dropping to 50% of incident levels in the top 1 and 2 cm, respectively. Isolated cell walls exhibited UV absorbance, possibly by sporopollenin, but this absorbance was weak in images of broken or plasmolyzed cells observed through a UV microscope. The cells also contained UV-absorbing cytoplasmic compounds, with the extrachloroplastic carotenoid astaxanthin providing most of the screening. Additional screening compound(s) soluble in aqueous methanol with an absorption maximum at 335 nm played a minor role. Thus, cells are protected against potentially high levels of UV radiation by the snow itself when they live several centimeters beneath the surface, and they rely on cellular screening compounds, chiefly astaxanthin, when located near the surface where UV fluxes are high.

Animals↗
PubMed2005

Population densities of corn flea beetle (Coleoptera: Chrysomelidae) and incidence of Stewart's wilt in sweet corn.

To quantify populations of the corn flea beetle, Chaetocnema pulicaria Melsheimer (Coleoptera: Chrysomelidae), and refine estimates of a threshold for its control to prevent Stewart's wilt caused by Erwinia stewartii, sequential plantings of 'Jubilee' sweet corn were made at 2-wk intervals from April or May through August or September 2001 and 2002 at four locations from southern to northern Illinois: Simpson, Brownstown, Champaign, and Mendota. Densities of C. pulicaria and incidence of Stewart's wilt were monitored weekly. At Mendota, where C. pulicaria populations were decimated by cold temperatures during winter 2000-2001, densities reached 33.3 beetles per 15-cm yellow sticky trap per day by September 2002, after a mild 2001-2002 winter. Maximum incidence of Stewart's wilt in single plots at Simpson, Brownstown, Champaign, and Mendota was 22, 36, 39, and 2%, respectively, in 2001, and 33, 47, 99, and 87%, respectively, in 2002. In 24 plots where beetle densities were < or =2 per trap per day, Stewart's wilt incidence was <5% in 20 plots. We propose that two corn flea beetles per trap per day be used as a threshold for insecticide application to seedlings to control C. pulicaria and minimize subsequent incidence of Stewart's wilt in processing sweet corn. Enzyme-linked immunosorbent assays indicated that E. stewartii incidence in C. pulicaria peaked at 67, 62, and 54%, respectively, at Simpson, Brownstown, and Champaign, in 2001, and at 71, 76, and 60%, respectively, in 2002. Further studies might allow the use of areawide or field-specific estimates of E. stewartii incidence in corn flea beetles for adjusting management decisions.

Animals↗
PubMed2005

Russian honey bee (Hymenoptera: Apidae) colonies: Acarapis woodi (Acari: Tarsonemidae) infestations and overwintering survival.

Honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies infested by parasitic mites are more prone to suffer from a variety of stresses, including cold temperature. We evaluated the overwintering ability of candidate breeder lines of Russian honey bees, most of which are resistant to both Varroa destructor Anderson & Trueman and Acarapis woodi (Rennie), during 1999-2001. Our results indicate that Russian honey bee colonies (headed by original and supersedure queens) can successfully overwinter in the north, even during adverse weather conditions, owing to their frugal use of food stores and their resistance to tracheal mite infestations. In contrast, colonies of Italian honey bees consumed more food, had more mites, and lost more adult bees than Russian honey bees, even during unusually mild winter conditions.

Animals↗
PubMed1998

Effects of controlled blood cooling on hemodynamic stability and urea kinetics during high-efficiency hemodialysis.

Although the use of cooled dialysate during hemodialysis is associated with stabilization of intradialytic BP, the effects of blood cooling on hemodynamics and urea kinetics in high-efficiency hemodialysis have not been completely studied. In particular, the effects of blood cooling have not been elucidated in very short-time, high K/V dialysis treatments, in which postdialysis urea rebound is maximized. In theory, blood cooling could increase urea compartmentalization during treatment and decrease dialysis efficacy. Measurements of cardiovascular hemodynamics and urea kinetics were performed in 15 patients (56 studies) during dialysis, using a blood temperature monitor with control of dialysate temperature. Dialysate temperature was adjusted to either lower the core temperature or raise the core temperature by, respectively, producing negative heat-energy exchange (cooled dialysis) or keeping heat-energy exchange in the extracorporeal circuit neutral (thermoneutral dialysis) so that energy was not transferred to or from the patient. Each subject was studied on both protocols, thereby allowing each individual to act as his own control. In cooled dialysis, heat-energy exchange in the extracorporeal circuit was -266+/-15 kJ per treatment, and dialysate temperature averaged 35.7+/-0.02 degrees C. In thermoneutral dialysis, heat-energy exchange in the extracorporeal circuit averaged 5+/-31 kJ per treatment, and dialysate temperature averaged 37.1+/-0.02 degrees C. Dialysate cooling resulted in a reduction in mean body temperature compared with thermoneutral therapy (-0.22+/-0.04 versus +0.31+/-0.05 degrees C). Cooling resulted in a greater increase in peripheral vascular resistance index (+515+/-160 versus + 114+/-92 dyn.sec/cm5 per m2), an increase in mean arterial pressure (+4+/-3 versus -4+/-4 mmHg), a reduction in the maximum intradialytic fall in mean arterial pressure (-10+/-2 versus -18+/-3, mmHg), and a reduction in staff interventions for hypotension or dialytic symptoms (6 of 28 versus 12 of 28 studies). These differences occurred without differences in the change in blood volume (-14.3+/-1.8% versus -13.9+/-2.2%) or cardiac index (-0.4+/-0.1 versus -0.4+/-0.2, L/min per m2). Urea rebound (37+/-4% versus 38+/-3%) and effective Kt/V (1.29+/-0.05 versus 1.32+/-0.06) were not different between groups. Thus, body temperature cooling can be used to stabilize BP and reduce intradialytic events requiring staff intervention without compromising the efficacy of treatment in high-efficiency dialysis.

Blood↗
PubMed1996

Effects of head cooling on sweat rate in exercising subjects wearing protective clothing and mask for pesticide.

This study examined the effects of the head cooling on the sweat rates in 6 healthy female subjects at an ambient temperature of 28 degrees C and a relative humidity of 60%. The exercising subjects wore protective clothing and a mask for pesticide. Head cooling was made by putting frozen gel strips on the parietal and the front head which were held by a net-bandage (with cooling). On separate days, the same experiments were made without head cooling (without cooling). The total weight of the frozen gel strips was 250 g. After the subjects rested for 15 min in a chair, they repeated three times the work/rest schedule of 15 min exercise on a bicycle ergometer (50 W) followed by 5 min rest. Frozen gel strips were put on the head just before the first exercise bout. Main results were summarized as follows: 1) The forearm sweat rate, heart rate and the changes in Tre from the initial level (delta Tre) were significantly lower "with cooling" than "without cooling". 2) The amount of sweat adhered to the clothing ensemble was significantly lower "with cooling" than "without cooling". 3) The changes in Tty from the initial level (delta Tty) tended to be clearly lower "with cooling" than "without cooling". 4) Skin temperatures of the forehead and the cheek under a mask tended to be lower "with cooling" than "without cooling". 5) Subjective sensation ratings seemed to be improved in most subjects "with cooling". Thus, it was concluded that head cooling seemed to be more effective in reducing thermal strain in working subjects wearing the protective clothing and a mask for pesticide at hot environments.

Adult↗
PubMed1996

Thermal balance of man in water: prediction of deep body temperature change.

Changes in rectal temperature and metabolic rate were continuously monitored in men immersed in water at 15, 20, 25, 30, and 35 degrees C. The subjects (12 healthy male students) wore swimming suits while either resting or doing leg exercise (delta M approximately 60 kcal.h-1.m-2 approximately 70 W.m-2) for 1 h. At all water temperatures below 30 degrees C, the metabolic rate increased but the rectal temperature fell continuously, resulting in hypothermia. The rate of fall in rectal temperature (cooling rate, CR, degrees C.h-1) was inversely proportional to water temperature (Tw, degrees C) according to the equation CR = 3.818-0.109 Tw in resting subjects and CR = 3.434-0.110 Tw in exercising subjects. At a given Tw the cooling rate was greater in resting than in exercising subjects and in lean than in obese subjects. From the relationships between the cooling rate and water temperature the duration of useful activity and the survival time were predicted for resting and exercising subjects of various fatness.

Adult↗
PubMed1996

Control of liquid cooling garments: technical control of body heat storage.

This paper describes a concept of how liquid cooling garments (LCG) can be automatically controlled by the objective physiological state. The technically controlled parameter was mean body temperature which was calculated from the measured rectal and mean skin temperature. This was motivated by the fact that mean body temperature is the basis for estimating body heat storage, a commonly used measure of thermal strain. Here the setpoint of mean body temperature was the individual value taken in a preceeding resting period and it was the task of the technical controller to keep the actual value of mean body temperature as close as possible to the setpoint. The most important tuning parameters of the controller were the weighting coefficients for rectal and mean skin temperature in the calculation for mean body temperature. The ratio of these two coefficients determined the degree of compensation for any rectal temperature shift by changing mean skin temperature. Test experiments were carried out (n = 5) in which the controller was able to clamp mean body temperature to the setpoint thereby preventing heat storage. Although exercise rate (75 W) was the same, sweating and warm discomfort occurred in some cases due to the individual rectal temperature rise. Another source of discomfort were delays or paradoxical time courses of rectal temperature at the start or end of exercise which were responsible for a delayed onset of cooling or heating. To avoid these effects, the oxygen consumption signal, which is very fast and directly correlated to the exercise rate, was added to the control loop. Each increase of this parameter above its resting level lowered suit temperature. As heat storage should not be completely rejected by this new signal pathway, the controller for mean body temperature still remained active. The repetition of the experiments showed that the load error in the control loop was smaller and the comfort level in transient phases higher. For a further improvement of this concept it is recommended that the weighting coefficients be tuned to the individual requirements.

Adult↗
PubMed1999

Raynaud's phenomenon in older adults: diagnostic considerations and management.

Raynaud's phenomenon (RP) is characterised by sensitivity to cold temperatures associated with either biphasic or uniphasic change in colour of the digits. Since few studies are available which include older adults, the prevalence of RP in the older adult population is estimated from surveys or studies of the general population. The causes of RP in older adults may differ significantly from those in young adults and, therefore, so would the evaluation of RP. Because of comorbitis that accompany advancing age, the management of RP in older adult patients must take into consideration toxicity and adverse reactions that may develop, especially in the frail individual. Although nonpharmacological therapy is preferable, slow-release calcium antagonists provide a relatively well tolerated and effective treatment for moderate to severe RP in older adult patients. Aggressive treatment including hospitalisation is appropriate for older adult patients during periods of critical digital ischaemia associated with RP.

Age Factors↗
PubMed1980

A different action of hypothermia on insulin release from the isolated, perfused rat pancreas, depending on the stimulating agent.

Two series of experiments were performed in parallel on the isolated perfused rat pancreas. The experimental conditions differed only as pertaining to temperature. In one series the organ and the perfusion liquid were maintained at 37.5 degrees C and in the other at 28 degrees C. The pancreases were perfused from the start of the experiments with a perfusion medium containing 8.3 mmol/l glucose. The effects of various stimulatory agents were studied (glucose 16.6 mmol/l, tolbutamide 0.4 mmol/l, acetylcholine 0.5 micromole/l, glucagon, 2.8 nmol/l, and L-isoprenaline 0.05 micromole/l). At 37.5 degrees C the insulin secretion induced by high glucose or tolbutamide, acetylcholine, and glucagon was biphasic and not statistically different. In all cases the hypothermia (28 degrees C) decreased insulin secretion. However, glucose-induced and tolbutamide-induced insulin secretion was more decreased than the secretion induced by acetylcholine and glucagon. The study of the secretion ratios obtained at 28 degrees C relative to 37.5 degrees C showed that the ratios for the glucose and tolbutamide groups were significantly lower than those obtained for acetylcholine and glucagon groups for both the first and the second phase. The ratios were not significantly different between glucose and tolbutamide on the one hand and acetylcholine and glucagon on the other hand. In all groups the ratios 28 degrees/37.5 degrees for the second phase were lower than those obtained during the first phase. L-isoprenaline induced only a weak increase in insulin secretion and this was not long lasting; this increase was not statistically different at both temperatures.

Acetylcholine↗
PubMed1997

Incidence of distal symmetric (sensory) neuropathy in NIDDM. The San Luis Valley Diabetes Study.

OBJECTIVE: To determine the incidence and risk factors for distal symmetric sensory neuropathy (DSN) in people with NIDDM. RESEARCH DESIGN AND METHODS: Prospective follow-up was conducted from 1988 to 1992 on 231 people free of DSN during the baseline period 1984-1988 (mean follow-up, 4.7 years). Subjects with incident DSN (n = 66) were defined by any two of three criteria: 1) bilateral paresthesia in legs or feet; 2) bilateral decreased or absent ankle reflexes; and/or 3) bilateral decreased or absent cold temperature discrimination in feet. Of all 66 cases, 42 had one positive follow-up visit; 14 cases had 2 positive follow-up visits. RESULTS: The overall incidence rate of DSN was 6.1 per 100 person-years (95% CI, 4.7-7.8). The rate for Hispanics (n = 164) and non-Hispanic whites (n = 67), adjusted for age, sex, and NIDDM duration, was 5.3 per 100 person-years (95% CI, 3.9-7.0) and 5.0 per 100 person-years (95% CI, 2.8-8.1), respectively. Adjusting for age and sex, higher glycohemoglobin level and lower C-peptide secretion were associated with increased DSN but were no longer predictive after accounting for duration of diabetes. Logistic regression models found significantly increased risk of DSN for insulin treatment, current smoking, and history of myocardial infarction. Duration was related to DSN incidence until insulin treatment was included. Other risk factors, including height, weight, family history of diabetes, peripheral vascular disease, hypertension, urinary albumin, protein:creatinine ratio, retinopathy, and alcohol use, were not significantly related to incident DSN. CONCLUSIONS: Hispanic and non-Hispanic whites with NIDDM have similar risks of DSN. Current cigarette smoking and a history of myocardial infarction may represent independent risk factors for DSN in addition to glycemic control.

Adult↗
PubMed1985

Frontal subcutaneous blood flow, and epi- and subcutaneous temperatures during scalp cooling in normal man.

Cooling of the scalp has been found to prevent hair loss following cytostatic treatment, but in order to obtain the hair preserving effect the subcutaneous temperature has to be reduced below 22 degrees C. In order to establish the relationship between epicutaneous and subcutaneous temperatures during cooling and rewarming and to measure the effect of scalp cooling on subcutaneous scalp blood flow, subcutaneous blood flow and epi- and subcutaneous temperatures were measured in the frontal region at the hairline border before and during cooling with a cooling helmet, during spontaneous rewarming of the cooling helmet and after removal of the rewarmed helmet in 10 normal subjects. Subcutaneous blood flow was reduced to about 25% of the postcooling control level during cooling. The flow was constantly reduced until the subcutaneous temperature exceeded 30-32 degrees C. A linear relationship between epicutaneous and subcutaneous temperatures could be demonstrated with the regression equation: s = 0.9 c + 4.9 (r = 0.99). In eight of the 10 subjects the subcutaneous temperature could be reduced below 22 degrees C with the applied technique. It is concluded that the hair preserving effect of scalp cooling during cytostatic treatment is mainly due to the metabolic effect of cooling, and only to a minor extent due to the flow reducing effect.

Adult↗
PubMedDate not supplied

The effect of air cooling on the radial temperature distribution of a single microwave hyperthermia antenna in vivo.

Canine skeletal muscle was heated with a single microwave antenna within a brachytherapy catheter driven at 2000 MHz. The radial, steady-state temperature distribution was measured with and without air cooling of the antenna, as produced by room temperature air flowing in the catheter at 7.5 l/min. The axial temperature distribution was also measured with air cooling. In the antenna junction plane the area heated to a given temperature increased by a factor of four with air cooling when the same antenna temperature was enforced. With the same maximum temperature enforced, the area would increase by a factor of 2.5 with air cooling. The axial temperature distribution was not compromised by air cooling.

Air↗
PubMed1990

Cornea derived neutrophil chemotactic factors: intracellular synthesis and release.

The present study was designed to test the hypothesis that the release of neutrophil chemotactic factors (NCF) from isolated corneas following hydrogen peroxide stimulation requires specific intracellular synthesis. For these studies, the epithelial surfaces of isolated rabbit corneas were preincubated with various inhibitors of protein synthesis (cycloheximide, 10 micrograms/ml, and puromycin, 50 micrograms/ml) and transcription (actinomycin D, 5 micrograms/ml) for 60 min prior to exposure of the corneas to glucose (G, 1 mg/ml) and glucose oxidase (GO, 20 U/ml) for 6 h at 37 degrees C. All three inhibitors decreased the levels of NCF recovered in the extracorneal fluids by 80-98%, suggesting that peroxide acts to upregulate NCF production at both the transcription and translation levels. When corneas were incubated with G/GO for 6 h at 12 degrees C or 4 degrees C instead of 37 degrees C, a reduction in the levels of NCF recovered in the supernatants was noted at 12 degrees C (46-91% inhibition) and at 4 degrees C (67-96% inhibition), suggesting that the synthesis of NCF at cold temperature was only reduced but not totally inhibited. To demonstrate that the observed reduction in chemotactic activity recovered from corneas incubated at 12 degrees C or 4 degrees C is not due to a temperature-dependent inhibition of NCF biosynthesis, but rather to a disruption of intracellular vesicular transport, temperature shift experiments were performed. Corneas were incubated with G/GO overnight at 12 degrees C or 4 degrees C prior to shifting to 37 degrees C for an additional 6 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

A population of human cord blood mononuclear cells with surface alpha fetoprotein.

Suspensions of mononuclear cells from adult peripheral blood (PBL) and mononuclear cells from cord blood (CBL) were examined for the presence of surface alpha-fetoprotein (AFP) using a fluoresceinated F(ab')2 fragment of rabbit IgG anti-human AFP. The mean proportion of CBL with AFP was increased (10%) when compared with PBL (1%) although some CBL specimens did not demonstrate such an increase (range 0--15%). The presence of AFP on CBL could be either due to cytophilic AFP attached to a unique surface receptor or intrinsic AFP synthesis. The following observations could not distinguish between these two possibilities: (1) After treatment with trypsin, only minor reappearance of surface AFP could be observed in AFP-free medium in contrast to the larger numbers observed in medium containing AFP. Such selective reappearance depending on the media could be related to either cytophilic attachment of heterologous or homologous AFP or preferential stimulation of intrinsic AFP synthesis. (2) The reappearance of AFP positive CBL following trypsin treatment and incubation in media with or without AFP containing sera was inhibited by cyclohexamide. Such inhibition could be due to inhibition of synthesis of an AFP surface receptor or intrinsic AFP. (3) The shedding of surface AFP observed at 2--4 degrees C could be due to release of exogenous cytophilic AFP or the continued "turnover" of intrinsic AFP without concomitant AFP synthesis due to the cold temperature. Finally, the removal of AFP positive cells via selective depletion of B cells using bead columns coated with IgG-anti-IgG and the absence of depletion of AFP positive cells after successive gradient centrifugation of E-rosettes and cells with IgG-Fc receptors are consistent with the identity of AFP positive CBL as cells without IgG-Fc receptors or lymphocytes without conventional T-cell markers as defined by E-rosettes.

Cell Membrane↗