Effects of ursodeoxycholic acid on conjugated bile acids and progesterone metabolites in serum and urine of patients with intrahepatic cholestasis of pregnancy

This study examined the effect of ambient temperature and feeding on brown adipose tissue (BAT) function and thermoregulation in lambs born either vaginally at term or by Caesarean section close to term. Immediately after birth lambs were placed in a warm (30 degrees C) or cool (15 degrees C) ambient temperature and measurements of colonic temperature and heat production recorded for 6 h. Lambs were fed 50 ml of colostrum when 5 h old. The amount of uncoupling protein and level of guanosine 5'diphosphate (GDP) binding in BAT was higher in vaginally delivered lambs than in lambs delivered by Caesarean section. For each delivery group, GDP binding was greater in lambs maintained at 30 degrees C than in lambs maintained at 15 degrees C. O2 consumption, CO2 production and colonic temperature only increased after feeding in lambs born by Caesarean section and maintained at 30 degrees C, a response that was accompanied by a decreased incidence of shivering. Irrespective of delivery temperature, plasma thyroid hormone concentrations and noradrenaline content of BAT were lower in lambs born by Caesarean section than in those born vaginally. Plasma cortisol concentrations were higher in lambs delivered by Caesarean section, as was adrenaline content of BAT in these lambs maintained at 30 degrees C. It is concluded that the thermoregulatory response to feeding in terms of changes in both recruitment of shivering and colonic temperature were observed only in lambs delivered by Caesarean section.     

Clinical and molecular genetic study in seven Japanese families with spinocerebellar ataxia type 6

This study examined the effect of thyrotrophin-releasing hormone (TRH) administration on thermoregulation in the newborn. Twin lambs were either delivered near-term by caesarean section or born vaginally at term. Colonic temperature, O2 consumption, CO2 production, breathing and heart rates, plus plasma thyroid hormone and nonesterified fatty acid (NEFA) concentrations and thermogenic activity (i.e. GDP binding) of brown adipose tissue (BAT) were measured. In caesarean section delivered lambs colonic temperature decreased rapidly after birth, a response that was greater in the group designated for TRH treatment, in which colonic temperature fell to below 36.0 degrees C at 80 min of life, prior to TRH administration. At this age colonic temperature had been restored to a mean of 38.70 degrees C in controls. TRH had no influence on the composition or thermogenic activity of BAT. The incidence of shivering was not influenced by TRH, but treated lambs maintained a higher rate of O2 consumption and ventilation compared with controls after colonic temperature had been restored to 38.56 degrees C. TRH appeared to promote fat oxidation as O2 consumption remained unchanged and CO2 production declined by a greater rate in treated lambs, resulting in a lower respiratory quotient compared to controls. Heart rate and plasma concentrations of NEFA increased following TRH administration although this did not result in values greater than controls. Normothermic lambs born vaginally had BAT with a greater thermogenic activity, higher plasma thyroid hormone and NEFA concentrations compared with caesarean section delivered lambs, but a thermogenic response was not observed to TRH despite a rise in thyroid hormone concentrations. In conclusion, TRH can improve thermoregulation, an effect that could be linked to an increase in fat oxidation.     

The effect of noradrenaline and 5-hydroxytryptamine injected into a lateral cerebral ventricle, on thermoregulation in the new-born lamb

1. Respiratory frequency, shivering, ear skin temperatures and rectal temperatures were observed following intraventricular injections of noradrenaline (NA), 5-hydroxytryptamine (5-HT) and saline (NaCl) into new-born lambs exposed to ambient temperatures of 4, 21, or 30 degrees C. 2. Intraventricular NA caused respiratory rate to decrease and body temperature to increase in the 30 degrees C environment. At 21 degrees C, it increased ear skin temperature but did not significantly affect rectal temperature. At 4 degrees C, NA decreased shivering and rectal temperature fell. 3. 5-HT elevated respiratory rate in the 30 degrees C environment and increased ear skin temperature in the 21 and 4 degrees C environments. In the 4 degrees C environment rectal temperature decreased. 4. In general, the change in rectal temperature was related to the dosage of drug administered. Control injections of NaCl had no significant effect on any of the variables measured. 5. The monoaminergic pathways involved in thermoregulation in the new-born lamb appear to be organized in a manner similar to that of the adult sheep and are functional at birth.     

Adipose tissue development during early postnatal life in ewe-reared lambs

This study examines the precise time course that brown adipose tissue (BAT) takes to adopt the characteristics of white adipose tissue in postnatal lambs. Perirenal adipose tissue was sampled from ewe-reared lambs within 1 h of birth and at 1, 2, 4, 7, 14, 21 and 30 days of age and analysed for the amount of mRNA for uncoupling protein (UCP), the amount and activity of UCP, and protein, mitochondrial protein and lipid content. This was combined with measurements of colonic temperature and jugular venous plasma concentrations of thyroid hormones and insulin-like growth factor-1 (IGF-1). Over the first 4-7 days of age, large quantities of UCP mRNA were associated with a peak in plasma triiodothyronine concentration at 2 days of age followed by a maximal amount and activity of UCP at 4 days and a basal colonic temperature of 39.3 degrees C. Between 7 and 30 days there was a large increase in lipid deposition as the amount and activity of UCP and the amount of UCP mRNA declined to basal values and colonic temperature was maintained at 40 degrees C. A significant positive relationship between perirenal adipose tissue lipid content and plasma IGF-1 concentration was observed throughout the study period. It is concluded that ovine adipose tissue maturation occurs in two distinct phases over the first month of life. The precise time scale of this process could be regulated in part by the lamb's body temperature which determines whether adipose tissue is required for heat production (i.e. BAT) or as an endogenous energy source (i.e. white adipose tissue).     

Ambient temperature effects on thermoregulation and endurance in anticholinesterase-treated rats

In sedentary animals, physostigmine (PH) administration resulted in a decreased core temperature that is ambient temperature (Ta) dependent. PH administration in rats exercising on a treadmill (26 degrees C, 50% rh, 11m/min, 6 degrees incline) decremented endurance and increased rate of rise of core temperature (heating rate, HR). This study was undertaken to examine the effects of Ta on the endurance and thermoregulatory decrements of PH-treated running rats. Adult male rats (510-530g) were given either 0.2ml saline (C) or 100 ug/kg physostigmine salicylate in 0.2 ml saline via tail vein 15 min prior to the start of running to exhaustion at 10, 15, 26, or 30 degrees C. In both C- and PH-treated groups, endurance decreased and HR increased with increasing Ta from 15 to 30 degrees C. At 15 and 26 degrees C the C rats ran significantly (p < .05) longer and had significantly lower HR than the PH rats: C15 = 90 +/- 8 min, 0.022 +/- 0.006 degrees C/min; C26 = 67 +/- 6, 0.051 +/- 0.007; PH15 = 57 +/- 5, 0.052 +/- 0.008; and PH26 = 43 +/- 6, 0.092 +/- 0.007. At 10 and 30 degrees C there were no significant differences between C and PH-treated rats. A Ta of 30 degrees C was too high for effective cooling in either group, and at 10 degrees C both groups were able to dissipate heat despite the increased metabolic rate of the PH-treated rats. The PH-treated rat model of cholinergic drug effect is useful at a Ta of 15 and 26 degrees C.     

Influence of maternal bodyweight on size, conformation and survival of newborn lambs

Although body condition score was not significantly different between light (<55 kg, n = 6) and heavy (> or =60 kg, n = 7) ewes at mating, it declined between Day 30 and Day 90 of gestation in light but not heavy ewes, and remained lower up to term. All ewes bore twins, delivered near term (Days 144-146) by Caesarean section. One lamb was immediately placed into a warm (30 degrees C; WD) and its twin into a cool (15 degrees C; CD) ambient temperature, and tissues were sampled at 0.5 h or 6 h. All CD lambs born to light ewes exhibited hypothermia and/or respiratory failure and did not survive longer than 30 min; these symptoms were not observed in their WD twins or any lamb born to heavy ewes. Total lamb birth weight, placental weight and fetal cotyledonary weight were lower with light than with heavy ewes. Lambs born to light ewes had less perirenal adipose tissue and smaller liver, heart, kidneys, brain, adrenals and thyroid, although their heart, brain and pancreas represented a larger proportion of total bodyweight; pancreas weight was similar to that in lambs born to heavy ewes. Hence, maternal bodyweight critically influences placental weight and lamb size and survival after birth.     

Circadian rhythms of rat internal temperatures and thermal ambiance (author's transl)]

Chronic recording of cerebellar and subcutaneous temperatures were carried out in rats maintained at different ambient temperatures in a 12 h light-dark cycle (light from 7 to 19 h). Cerebellar and subcutaneous temperatures followed a rhythm with a period of 24 h with acrophase at 1 h and an amplitude of 0.75 degrees C. The amplitude and acrophase were not altered by modification of the ambient temperature (20-25-30-34 or 35 degrees C), but each elevation of ambient temperature produced a rise in the mean internal temperature of the rat. This rise, hardly perceptible at ambient temperatures of 25 and 30 degrees C, reaches 0.5 degrees C between 20 and 25 degrees C and 1 degrees C between 30 and 34 degrees C. This elevation of temperature was maintained for the duration of the 10 days of observation. These results pose at least three questions: the degree of liaison between the rhythms of activity (waking) and temperature; the lability of the mean internal temperature, which alter with ambient temperature while the amplitude of the circadian rhythm is unaltered and the absence of reduction of mean interanl temperature several days exposure to a raised ambient temperature, even when activity and metabolism are reduced by the second day of exposure.     

Mechanisms of temperature regulation in heat-acclimated hamsters

Mechanisms of temperature regulation were assessed by measurements of oxygen consumption (VO2), body temperature (Rre = rectal, Tsk = skin), evaporative water loss (EWL), regional distribution of blood flow, and blood volume. Hamsters (Mesocricetus auratus) were acclimated to ambient temperatures of 34 or 22 degrees C. VO2 of 34 degrees C-exposed animals was reduced to 50% of that of controls at 22 degrees C, whereas EWL with heat exposure was almost double that of controls. Heat-acclimated animals had a slightly elevated Tre in comparison to 22 degrees C-acclimated animals, whereas there was a marked elevation in Tsk with heat exposure, in contrast to control animals at 22 degrees C. Blood flow distribution measurements indicated that with 34 degrees C exposure there was a decreased flow in liver, kidney, and intestine, whereas there was an increase to the carcass. Red cell and plasma volumes in heat-acclimated hamsters were decreased belwo the values of the 22 degrees C controls. Heat acclimation of the fhamster appears to involve reduced VO2 and increased WEL. Convective and radiative heat loss appear to be maintained by increased Tsk with heat exposure. Nonevaporative heat dissipation mechanisms are of primary importance in thermoregulation of the heat-acclimated hamster, and it is suggested that this is mediated by increased peripheral blood flow with reduced flow to the viscera.     

Ultrasound measurement of bone

The importance of photoperiod and ambient temperature on the accumulation of cadmium in the liver and kidneys of bank voles was determined in the present study. Males and females, aged 1 month, were given 3.0 micrograms Cd ml-1 drinking water and divided into four groups according to photoperiod (16 h light/8 h dark and 8 h light/16 h dark) and ambient temperature (20 or 5 degrees C); liver and kidneys were removed for cadmium as well as copper, iron and zinc analyses at the end of 6 weeks. Bank voles exposed to 5 degrees C in both photoperiods consumed approximately 30% less water containing cadmium than those kept at 20 degrees C. However, the total accumulation of cadmium in the liver and kidneys of males and females exposed to the low temperatures was 4.3-4.8 and 2.2-3.3 times less than that in animals maintained at room temperature in the long and short photoperiod, respectively. Simultaneously, the low temperature brought about an increase in the copper concentrations in the liver (12-43%) and kidneys (47-78%), giving rise to an inverse correlation between the cadmium accumulation and the tissue copper concentration. In contrast to cadmium and copper, the concentrations of iron and zinc were affected primarily by photoperiod. These findings indicate that ambient temperature is an important determinant of cadmium retention in the bank vole. It appears that low temperature decreases tissue cadmium accumulation not only by reducing cadmium intake but also through changes in copper metabolism.     

Energy expenditure for thermoregulation and locomotion in emperor penguins

During the antarctic winter emperor penguins (Aptenodytes forsteri) spend up to four mo fasting while they breed at rookeries 80 km or more from the sea, huddling close together in the cold. This breeding cycle makes exceptional demands on their energy reserves, and we therefore studied their thermoregulation and locomotion. Rates of metabolism were measured in five birds (mean body mass, 23.37 kg) at ambient temperatures ranging from 25 to -47 degrees C. Between 20 and -10 degrees C the metabolic rate (standard metabolic rate (SMR)) remained neraly constant, about 42.9 W. Below -10 degrees C metabolic rate increased lineraly with decreasing ambient temperature and at -47 degrees C it was 70% above the SMR. Mean thermal conductance below -10 degrees C was 1.57 W m-2 degrees C-1. Metabolic rate during treadmill walking increased linearly with increasing speed. Our data suggest that walking 200 km (from the sea to the rookery and back) requires less than 15% of the energy reserves of a breeding male emperor penguin initially weighing 35 kg. The high energy requirement for thermoregulation (about 85%) would, in the absence of huddling, probably exceed the total energy reserves.     

Effects of various ambient temperatures and of heating and cooling the hypothalamus and cervical spinal cord on antidiuretic hormone secretion and urinary osmolality in pigs

1. Plasma ADH concentration, urinary and plasma osmolality and haematocrit were measured in young pigs placed in cold, thermoneutral, warm and hot ambient temperatures. In some experiments a thermode placed in the hypothalamus or over the cervical spinal cord was heated or cooled at various ambient temperatures. 2. Plasma ADH concentration remained at a low level (0-5--5 muu. ml.-1) over 2 hr or 3 hr periods when the pigs were in cold, thermoneutral or warm ambient temperatures. A hot environment, which caused a marked rise in the pigs' rectal temperature, was associated with a large rise in plasma ADH level. 3. The rise in plasma ADH level which occurred during an increase in body temperature was consistently and completely suppressed by simultaneous cooling of the thermode in the pre-optic region to 5 to 10 degrees C. When the thermode was in the region of the supraoptic nucleus the rise in ADH was only partly suppressed, and when it was over the cervical cord it was only sometimes suppressed. 4. Cooling the thermodes in any position at a cold or thermoneutral ambient temperature, or heating them at a thermoneutral or warm ambient temperature, caused no consistent change in ADH. 5. A diuresis, with a urinary flow-rate of at most 1 ml. min-1 and minimal urinary osmolality of 53 m-osmole kg-1, was observed on only three occasions, twice during cooling of a thermode in the hypothalamus and once after the end of a period when the thermode was heated. In each case, the plasma ADH was less than 2 muu. ml.-1. 6. A slight rise of haematocrit in cold ambient conditions and a slight fall in the warm were observed. Otherwise changes in haematocrit were trivial, and a shift of water between vascular system and interstitium could not be invoked to account for changes in ADH levels. Observed variation of plasma osmolality was also slight.     

Malignant melanoma in Europe: changes in mortality rates (1970-90) in European Community countries

We measured metabolic rates (mL O2 h-1, converted to kcal d-1), deep body temperatures (degree C), and skin temperatures (degree C) and calculated whole-animal thermal conductances (mL O2 g-1 h-1 degree C-1) of five 3-yr-old harbor seals (Phoca vitulina concolor) at air temperatures between -20 degrees and 35 degrees C. The mean thermal neutral zone of these seals extended from a lower critical temperature of -12.9 degrees +/- 1.6 degrees C (SD) to an upper critical temperature of 28.6 degrees +/- 1.7 degrees C. Hyperthermia was observed at an ambient air temperature of 35 degrees C. Mean standard metabolic rate was 1,553.6 +/- 168.2 kcal d-1, about 1.2 times the value expected for adult animals of similar body mass (mean mass = 49.2 +/- 7.5 kg). Mean deep body temperature increased from 37.5 degrees +/- 0.30 degrees C at an ambient temperature of 30 degrees C and reached 39.3 degrees +/- 0.33 degrees C at an ambient temperature of 35 degrees C. Skin temperature decreased with decreasing ambient temperature but remained well above ambient temperature. Mean whole-animal thermal conductance decreased from an ambient temperature of 35 degrees C until it reached a minimum value of 0.007 mL O2 g-1 h-1 degree C-1 at -4.0 degrees C; it then increased with a further decrease in ambient temperature. In comparison to the thermal limits of the same seals during their first year of life, the results indicate a broadening of the thermal neutral zone with age: an 11 degrees C decrease in the lower critical temperature and a 3.5 degrees C increase in the upper critical temperature. These findings suggest that warm ambient air temperatures should not pose any particular thermoregulatory problems for larger and older harbor seals, even beyond the limits of their current annual distribution.     

Schedule-induced polydipsia: Effect of water temperature, ambient temperature, and hypothalamic cooling.

Conducted 3 polydipsia experiments with a total of 26 female Sprague-Dawley rats, 6 of which were implanted with thermodes and thermistors and 2 of which were implanted with thermistors alone in the medial preoptic area or posterior hypothalamus. A cold (5.C) ambient temperature reduced the amount of water consumed by food-deprived Ss tested with a VI schedule of reinforcement, while a warm (30.C) ambient increased water intake. Response rate in the cold was twice that in a neutral temperature. A hot (38.C) ambient suppressed the rate of responding and drinking. Cooling the hypothalamus substantially reduced water intake in a neutral ambient temperature. Ambient temperature affected the volume of a drink but not the frequency of drinking, while hypothalamic cooling affected both volume and frequency. Water temperature had little effect on polydipsia although less cold water was consumed than warm water. It is concluded that schedule-induced polydipsia is a temperature-dependent phenomenon. (39 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regional brain heating during microwave exposure (2.06 GHz), warm-water immersion, environmental heating and exercise

Nonuniform heating may result from microwave (MW) irradiation of tissues and is therefore important to investigate in terms of health and safety issues. Hypothalamic (Thyp), cortical (Tctx), tympanic (Tty), and rectal (Tre) temperatures were measured in rats exposed in the far field, k-polarization (i.e., head pointed toward the transmitter horn and E-field in vertical direction) to two power densities of 2.06 GHz irradiation. The high-power density (HPM) was 1700 mW/cm2 [specific absorption rate (SAR): hypothalamus 1224 W/kg; cortex 493 W/kg]; the low-power density (LPM) was 170 mW/cm2 (SAR: hypothalamus 122.4 W/kg; cortex 49.3 W/kg). The increase (rate-of-rise, in degrees C/s) in Thyp was significantly greater than those in Tctx or Tre when rats were exposed to HPM. LPM produced more homogeneous heating. Quantitatively similar results were observed whether rats were implanted with probes in two brain sites or a single probe in one or the other of the two sites. The qualitative difference between regional brain heating was maintained during unrestrained exposure to HPM in the h-polarization (i.e., body parallel to magnetic field). To compare the temperature changes during MW irradiation with those produced by other modalities of heating, rats were immersed in warm water (44 degrees C, WWI); exposed to a warm ambient environment (50 degrees C, WSED); or exercised on a treadmill (17 m/min 8% grade) in a warm ambient environment (35 degrees C, WEX). WWI produced uniform heating in the regions measured. Similar rates-of-rise occurred among regions following WSED or WEX, thus maintaining the pre-existing gradient between Thyp and Tctx These data indicate that HPM produced a 2-2.5-fold difference in the rate-of-heating within brain regions that were separated by only a few millimeters. In contrast, more homogeneous heating was recorded during LPM or nonmicrowave modalities of heating.     

Limbus-based vs fornix-based conjunctival flap in combined glaucoma and cataract surgery with adjunctive mitomycin C

1. The effects of relative humidity on growth rate and thermoregulation at high ambient temperature were evaluated in turkeys. Male turkeys were exposed to ambient temperature (Ta) of 35 degrees C and relative humidity (RH) of 40% to 75% and 50% to 85%, at ages of 13 to 19 weeks (trial 1) and 10 to 15 weeks (trial 2), respectively. 2. Body weight and food intake in both trials increased as RH increased up to 70% to 75%. When RH increased further to 80% to 85% (Trial 2) both body weight and food intake declined significantly. 3. Blood CO2 partial pressure (pCO2) did not change significantly at different RHs (trial 1). However, in trial 2 it dropped significantly at 80% to 85% RH. This response coincided with an increase in blood pH. 4. The effect of RH on body temperature (Tb) was not significant in either trial. 5. Triiodothyronine (T3) concentrations increased with the increase in RH up to 70% to 75% RH (trials 1 and 2). A significant decrease was observed when RH was further increased to 80% to 85% RH (Trial 2). Positive linear correlations between T3 and food intake or weight gain were observed in both trials. 6. The results indicate that turkeys can thermoregulate efficiently in the face of extreme changes in RH and that only at high RH (above 75%) did the performance of turkeys deteriorate.     

A method for determination of thermally motivated behavior (author's transl)

Constant body temperature in homeothermic organisms results from autonomic and behavioral thermoregulatory reactions. The input variables for thermally motivated behavior are temperatures of the skin and of the hypothalamus. Our aim was to determine the behavioral side of thermoregulatory reactions under the influence of drugs interfering with normal body temperature. Initial experiments were made with phentolamine, which at an ambient temperature of + 4 degrees C causes a dose dependent hypothermia. Rats were trained in a cold box to press a lever and were rewarded by a certain amount of warm air. Trained rats were able to raise the temperature in the box from -4 degrees C up to + 4 degrees C at a response rate of 0.5 min. Treated with phentolamine (3.7-15 mg/kg) these rats increased the rate of lever pressing dose dependently, i.e. they increased their ambient temperature. The hypothermic effect of the drug was therby reduced to a certain extent. Using this method it can be determined whether a drug influences body temperature at the level of autonomic reactions or at that of thermally motivated behavior or at those of both.     

Effects of ambient temperature on broiler mineral balance partitioned into urinary and faecal loss

1. Two experiments were conducted on control (intact) and colostomised 4 to 7 week old broilers to evaluate the influence of 24 degrees C, diurnally cycling 24 to 35 degrees C and chronic 35 degrees C ambient temperatures on broiler mineral balance, urinary and faecal mineral excretion and urinary osmolar characteristics. 2. In the first experiment, colostomy had no significant effect on mineral balance. However, broilers exposed to high cycling ambient temperature reduced their retention of phosphorus, potassium, sodium, magnesium, sulphur, manganese, copper and zinc compared with birds housed at 24 degrees C. 3. Despite the minimal effect of high ambient temperature on urine production, minerals excreted disproportionately excreted in urine included potassium, magnesium, phosphorus and sulphur while copper and magnesium were lost primarily via the faeces. 4. In the second experiment, exposure to 35 degrees C increased urine output from 50.7 ml/12 h per kg of body weight at 24 degrees C to 101.3 ml/12 h per kg of body weight and was associated with an increased urine:water ratio and reduced urine osmolality. 5. Reduced urinary chloride and higher potassium, phosphorus, sulphur, sodium, magnesium, calcium and manganese excretion was observed for broilers housed in under high ambient temperatures compared to 24 degrees C. 6. These studies suggest that high ambient temperatures adversely influence mineral metabolism and, furthermore, that the route of excretion varies with the specific mineral and the environmental temperature exposure.     

The vitamin B 6 requirements of the laying hen for reproduction

Some parameters related to withstanding severe cold (-20 degrees C) after administration of increasing doses of ethanol were investigated using guinea-pigs. The animals had been reared either at 22-23 degrees C or at 17-18 degrees C. They received ethanol in doses of 0.8 g, 1.2 g, 1.4 g or 1.6 g per kg of body weight. The fall of rectal temperature and its level at death were registered. The survival time, ethanol concentration in the blood and the brain, serum glucose and serum FFA at death were determined. In the animals reared at 22-23 degrees C the ethanol doses of 1.2-1.6 g/kg caused a significant shortening of the survival time and accelerated the fall of the rectal temperature. In addition the rectal temperature at death after ethanol was lower than in the controls. In the animals reared at 17-18 degrees C the ethanol doses used did not have any significant effect on the survival time and the rectal temperature. In both groups, ethanol concentration in the brain was lower (about 20-40%) than in the blood, the difference being greater in the group reared at 22-23 degrees C. Ethanol had no effect on the glucose concentrations. Serum FFA levels were slightly lower in animals reared at 22-23 degrees C than in those grown in the cooler temperature. It became evident that ethanol has a dose dependent deleterious effect on the thermoregulation of animals reared in warm (22-23 degrees C). The effect was seen at and above the dose of 1.2 g/kg. The results indicate further even a slight acclimation to cold was able to abolish the effect of these rather great doses of ethanol in severe cold exposure.     

Thermal homeostasis in pregnant rats during heat stress.

Sprague-Dawley rats exposed to inescapable heat stress maintained a controlled hyperthermia while increasing heat loss by cutaneous vasodilatation and by grooming behavior. In nonpregnant Ss, the evaporation of saliva groomed onto the body surfaces increased exponentially as a function of ambient temperature above 36°C. In contrast, Ss in an advanced stage of pregnancy became dependent on grooming behavior for thermoregulation of ambient temperatures of 30-36°C. This was associated with a decrease in the body temperature threshold for salivary secretion from the submaxillary gland, which then began at approximately the same body temperature as cutaneous vasodilatation. The pregnant Ss maintained a lower level of controlled hyperthermia during heat stress than did nonpregnant Ss. This appeared to result from a decreased production of metabolic heat, reduced insulation on the ventral surface, and an increased motivation to keep cool during heat stress. These changes met the increased need for thermolysis during pregnancy and provided for thermal homeostasis both in the pregnant rat and in the unborn fetuses. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of silver and copper ions on survival of Legionella pneumophila in tap water

In vitro studies were performed to give information about the required metal concentrations in decontaminating Legionella-loaded warm water systems with the electrochemical generation of Ag+ and Cu2+ ions. The influence of Ag and Cu ions, as single compounds and in combination, on the survival of Legionella pneumophila (serogroup 6) was determined in tap water at 45 degrees C. Marked differences were detected in the action of these metals. Ag produced a much stronger inhibition than Cu. No additive effect was demonstrated when using Ag/Cu-combinations in the ratio of 1:10. In this case only the Ag-induced inhibition was detected. After 1 h of incubation at 45 degrees C a concentration of 80 + 800 micrograms/L Ag + Cu was needed to produce the maximal inhibitory effect (a 5 log decrease). An identical effect was seen after exposure to 20 + 200 micrograms/L Ag + Cu in the long-term action (24 h of incubation). The minimum inhibitory concentration after long-term incubation was 5 + 50 micrograms/L Ag + Cu. These metal concentrations produced a 1 log reduction. The in vitro results are discussed under consideration of earlier investigations after metering Ag and Cu into a Legionella-loaded water system and generated the following conclusions: In the beginning highly contaminated water systems at 45 degrees C need concentrations between 40 and 80 micrograms/L Ag + 400 to 800 micrograms/L Cu to kill Legionellas. After effective reduction of Legionella concentration of at least some logarithmic powers a slow constant maintenance concentration of 5 to 20 micrograms/L Ag + 50 to 200 micrograms/L Cu could be applied. At 22 degrees C the in vitro inactivation response is much lower. On the other hand in warm water systems with temperatures of 50 to 60 degrees C lower metal concentrations are sufficient.