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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to assess the utility of the thermoregulatory system as an end point in predicting the toxicity of various short-chain alcohols. Male Fischer rats developed significant hypothermia following acute administration (ip) of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, or 2-butanol. The hypothermic responses to the six alcohols all showed similar segmented responses characterized by a threshold dose below which no change in body temperature occurred, and a suprathreshold regression with increasing dose causing greater hypothermia. Relative potency of the alcohols was assessed using both the threshold dose to cause hypothermia and the dose that would cause body temperature to decrease by 1 degree C. Both measures gave the progression of toxicity from least to most potent of methanol less than ethanol less than 2-propanol less than 1-propanol less than 2-butanol less than 1-butanol. The effective dose of each alcohol was compared to its membrane/buffer partition coefficient (Pm/b), and there was a high inverse correlation between the hypothermic dose of an alcohol and its lipid solubility. That the potency of an alcohol was strongly correlated with its Pm/b suggests that the membrane disordering theory of narcosis may also be used to explain the hypothermic action of alcohols.
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PMID:Hypothermic effects of a homologous series of short-chain alcohols in rats. 199 24

While methanol neurotoxicity has been studied for decades, there are very few data available on the thermoregulatory effects of methanol exposure. This paper will present the results of three studies designed to assess the effects of methanol on body temperature and behavioral thermoregulation in Fischer and Long Evans rats. The first study measured the onset of body temperature changes following methanol exposure. Following gavage of 3 g/kg methanol (20% w/v in saline), brain temperature (Tbr) of Fischer rats decreased 1.5 degrees C within 35 min. A similar volume of saline led to transient increases in Tbr. A second study assessed the time course of changes in body temperature by measuring colonic temperature (Tc) hourly following IP injection of saline or 1 or 3 g/kg methanol. The highest dosage of methanol caused a significant hypothermia in both Fischer and Long Evans rats. The hypothermia reached its nadir in both strains at 1-2 hours and partially recovered within the 6 hour experiment. The third study measured the effects of methanol on behavioral thermoregulation. Fischer and Long Evans rats were gavaged with saline or 1-3 g/kg methanol and placed in a temperature gradient. After 90 min in the gradient, rats of both strains which received 2 or 3 g/kg methanol had a significantly lower Tc than control rats. However, the methanol-treated rats remained in the cool end of the gradient and did not prevent the hypothermic effect of the alcohol. The absence of an observed effect on behavioral temperature selection suggests that methanol may interfere with thermal sensation.
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PMID:Thermoregulatory effects of methanol in Fischer and Long Evans rats. 231 59

To measure the effect of methanol on autonomic thermoregulation, male Fischer rats were injected intraperitoneally with saline or 1 or 3 g/kg methanol (20% w/v in saline). The rats were then placed in a chamber, set at an ambient temperature (Ta) of 5, 15, 25, or 35 degrees C, for 60 min while total activity, metabolic rate (MR), evaporative water loss (EWL), and dry thermal conductance were measured. After 60 min, the rat was removed from the chamber and colonic temperature (Tc) was measured. The rats developed a significant hypothermia following the 3 g/kg dosage of methanol at Ta's from 5 to 25 degrees C, while the change in Tc at 35 degrees C was not significant. Total activity decreased following 3 g/kg methanol at Ta's from 15 to 35 degrees C. At a Ta of 25 degrees C, MR was at basal levels and methanol had no effect, but at the other Ta's, where MR was elevated, methanol caused a significant reduction in MR. EWL and thermal conductance were elevated at 35 degrees C in control rats, and methanol reduced EWL at this Ta while it had no effect on conductance at this or any other Ta. These data suggest that the methanol-induced hypothermia and its depressive effect on activity and MR were related. The effect of methanol on the heat loss effectors (EWL, conductance) was not significant or was in the direction of heat conservation. Thus, methanol exposure leads to a significant hypothermia in rats by an inhibitory action on heat production pathways.
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PMID:Effects of methanol on autonomic thermoregulation of rats at different ambient temperatures. 237 99

Aqueous and organic extractions of ground seeds of Cassia occidentalis were obtained. Chickens were dosed with extracted material to assess the toxicity of the extracts. Organic extracts with methanol, ethanol, chloroform, ethyl acetate, and benzene were ineffective in removing the toxin from the seeds. Aqueous extractions, using 25 mM sodium bicarbonate or 250 mM sodium citrate, removed the toxin from the seeds, but left the toxin bound to particulate matter in the extract. Addition of Triton X-100 to the aqueous buffers effectively solubilized the toxin from the particulate matter. Signs of intoxication in the chickens were loss of weight, weakness, diarrhea, hypothermia, occasionally ataxia, and recumbency; then death. Gross lesions included paleness of skeletal and cardiac muscles and congestion of the liver. Microscopic lesions in muscle tissue were vacuolation, proliferation of sarcolemmal nuclei, and separation of myofibrils. Electron microscopic examination revealed disruption of mitochondrial cristae and swelling and rupture of mitochondria.
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PMID:Preliminary isolation of a myodegenerative toxic principle from Cassia occidentalis. 688 74

The rat paw edema due to carrageenan, yeast, and dextran was dose-dependently antagonized by oral administration of ethanol. Carrageenan-induced paw edema was also inhibited by methanol, 1-propanol, and 1-butanol. The rat carrageenan pleurisy was reduced by oral pretreatment with methanol, ethanol, 1-propanol, 1-butanol, and dimethyl sulfoxide. Central depression, altered adrenal functions, increased osmolality, and hypothermia were no important factors for these actions of solvents. It is concluded that the inhibitory effect of ethanol on inflammatory responses increases the susceptibility of alcoholics to infection.
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PMID:Anti-inflammatory effect of ethanol and other alcohols on rat paw edema and pleurisy. 740 55

This research was undertaken to determine potential interactions among chemical and physical agents. Radiofrequency (RF) radiation is used in numerous workplaces, and many workers are concurrently exposed to RF radiation and various chemicals. The developmental toxicity of RF radiation is associated with the degree and duration of hyperthermia induced by the exposure. Previous animal research indicates that hyperthermia induced by an elevation in ambient temperature can potentiate the toxicity and teratogenicity of some chemical agents. We previously demonstrated that combined exposure to RF radiation (10 MHz) and the industrial solvent, 2-methoxyethanol (2ME), enhanced teratogenicity in rats. Interactions were noted at even the lowest levels of 2ME tested, but only at hyperthermic levels of RF radiation. The purpose of the present research is to investigate if the interactive effects noted for RF radiation and 2ME are unique to these agents, or if similar interactions might be seen with other chemicals. Because methanol is widely used as a solvent as well as fuel additive, and, at high levels, is teratogenic in animals, we selected methanol as a chemical to address generalizability. Based on the literature and our pilot studies, 0, 2, or 3 g/kg methanol (twice, at 6-hour intervals) were administered on gestation day 9 or 13 to groups of 10 Sprague-Dawley rats. Dams treated on day 9 were given methanol and exposed to RF radiation sufficient to maintain colonic temperature at 41 degrees C for 60 minutes (or sham). Those treated on day 13 were given methanol plus either 0 or 100 mg/kg 2ME. Because we observed that methanol produced hypothermia, some groups were given the initial dose of methanol concurrently with the RF or 2ME, and others were given the first dose of methanol 1.5 hours prior to RF or 2ME. Dams were sacrificed on gestation day 20, and the fetuses were examined for external malformations. The results indicate that RF radiation or methanol on day 9 increased the incidence of resorbed fetuses, but no interactive effects were observed. The resorptions were highest in groups given the experimental treatments 1.5 hours apart. The higher dose of methanol also reduced fetal weights. Administration of 2ME or methanol on day 13 increased the rate of malformations, and there was evidence of a positive interaction between 2ME and methanol. Fetal weights were reduced by 2ME and methanol alone, but no interaction was observed. Also, separation of the dosing with the teratogens did not affect the results. These results point out that interactions in developmental toxicology, such as those of RF radiation, 2ME, and methanol that we have studied, are complex, and such interactions cannot be fully understood or predicted without more research. It is important that combined exposure effects be considered when developing both physical agent and chemical agent exposure guidelines and intervention strategies.
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PMID:Developmental toxicity interactions of methanol and radiofrequency radiation or 2-methoxyethanol in rats. 1135 70

Hypothermic and cardiovascular activities of the methanol extract of Jacaranda mimosaefolia leaves were tested. To evaluate the hypotensive properties, anesthetized rats were used and temperature, blood pressure, and cardiac frequency were recorded. In addition, the in vitro effect produced by the extract on induced contraction with norepinephrine (NE) in rat aorta rings was evaluated. The extract produced a significant hypothermic effect with a maximum at 2 h, an effect which was accompanied by hypotension and low cardiac frequency, physiological conditions that were again re-established to the following 2 h. In isolated aorta preparations norepinephrine antagonistic effect was not correlated with the presence of Ca2+, pD2 for NE was modified by the extract, an effect that could explain a blockade of the adrenergic receptors.
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PMID:Hypotensive effect of the hydroalcoholic extract from Jacaranda mimosaefolia leaves in rats. 1570 69

It has been shown in a previous work that the methanol extract obtained from the aerial part in blossom of Hypericum canariense L. and Hypericum glandulosum Ait. was active in the tetrabenazine and forced swimming test. In the present study, the central nervous effect of the aqueous, butanol and chloroform fractions obtained from the methanol extracts of these Hypericum species was investigated in mice, particularly in animal models of depression. It was found that the immobility time in the forced swimming test was significantly reduced by the butanol and chloroform fraction of both species assayed, producing no effects or only a slight depression on spontaneous motor activity when assessed in a photocell activity meter. In this regard, the efficacy of the chloroform extract from Hypericum glandulosum Ait. (500 mg/kg p.o.) in the forced swimming test was comparable to that of the tricyclic antidepressant imipramine (50 mg/kg p.o.). In addition, the Hypericum glandulosum chloroform fraction was also effective in antagonizing the ptosis induced by tetrabenazine. Moreover, Hypericum canariense butanol fraction and Hypericum glandulosum chloroform fraction produced a slight but significant hypothermia. Taken together, these data demonstrate that the butanol and chloroform fractions from Hypericum canariense and Hypericum glandulosum possess antidepressant-like effects in mice, providing further support for the traditional use of these plants in the Canary Islands folk medicine against central nervous disorders.
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PMID:Antidepressant properties of some Hypericum canariense L. and Hypericum glandulosum Ait. extracts in the forced swimming test in mice. 1574 Aug 93

We previously reported that oral administration of the methanol extract obtained from the aerial part in blossom of Hypericum reflexum L. fil. was active in the tetrabenazine and forced swimming test. In the present study, the effect of the aqueous, butanol and chloroform fractions obtained from the methanol extract of this species on the central nervous system was investigated in mice, particularly in animal models of depression. Antidepressant activity was detected in the butanol and chloroform fractions of this species using the forced swimming test since both fractions induced a significant reduction of the immobility time, producing no effects or only a slight depression on spontaneous motor activity when assessed in a photocell activity meter. Moreover, these fractions did not alter significantly the pentobarbital-induced sleeping time. On the other hand, the chloroform fraction produced a slight but significant hypothermia and was also effective in antagonizing the ptosis induced by tetrabenazine. Furthermore, the butanol fraction produced a slight potentiation of the head twitches and syndrome induced by 5-HTP. Taken together, these data indicate that the butanol and chloroform fractions from Hypericum reflexum possess antidepressant-like effects in mice, providing further support for the traditional use of these plants in the Canary Islands folk medicine against central nervous disorders.
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PMID:Antidepressant activity of some Hypericum reflexum L. fil. extracts in the forced swimming test in mice. 1738 28

The archived head-space chromatograms of ethanol determinations in autopsy blood in the years 1996-2003 were analysed. One hundred and two cases with elevated acetone level >250mmol/l were selected in which the biochemical profiles of volatile alcohols (methanol, isopropanol and n-propanol) were determined after "post-hoc" calibration of the constant internal standard. Based on the files obtained from the Prosecutor's Office, the circumstances of death and those preceding death (alcoholism, prolonged or single consumption of alcohol, intoxications with other substances, hypothermia, undernourishment, diabetes) were analysed and the most probable cause of endogenous or exogenous ketonaemia were determined. All cases of unexplained deaths in alcoholics with the ethanol concentration <0.4g/l occurred after withdrawal of long-term consumption of alcohol while all alcoholics with the ethanol concentration >0.4g/l died during the so-called drinking bout. In the group of hypothermia-related deaths with ethanol concentrations <0.4g/l, the acetone concentration was statistically significantly higher than that in hypothermia group with ethanol concentration >0.4g/l in which "congeneric" concentrations of methanol and isopropanol were additionally observed. Furthermore, an algorithm of further diagnostic management was suggested to distinguish the most likely origin of acetonaemia, i.e. accumulation of exogenous "denaturants" of alcohol consumed and cases of endogenous ketogenesis.
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PMID:Acetonaemia as an initial criterion of evaluation of a probable cause of sudden death. 1884 83


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