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At least 973 records · Page 54Linked to original sources
PubMed2005

Cooling methods used in the treatment of exertional heat illness.

OBJECTIVE: To review the different methods of reducing body core temperature in patients with exertional heatstroke. METHODS: The search strategy included articles from 1966 to July 2003 using the databases Medline and Premedline, Embase, Evidence Based Medicine (EBM) reviews, SPORTDiscus, and cross referencing the bibliographies of relevant papers. Studies were included if they contained original data on cooling times or cooling rates in patients with heat illness or normal subjects who were subjected to heat stress. RESULTS: In total, 17 papers were included in the analysis. From the evidence currently available, the most effective method of reducing body core temperature appears to be immersion in iced water, although the practicalities of this treatment may limit its use. Other methods include both evaporative and invasive techniques, and the use of chemical agents such as dantrolene. CONCLUSIONS: The main predictor of outcome in exertional heatstroke is the duration and degree of hyperthermia. Where possible, patients should be cooled using iced water immersion, but, if this is not possible, a combination of other techniques may be used to facilitate rapid cooling. There is no evidence to support the use of dantrolene in these patients. Further work should include a randomised trial comparing immersion and evaporative therapy in heatstroke patients.

Body Temperature↗
PubMed1996

Assessment of the biodegradation potential of psychrotrophic microorganisms.

Bioremediation of polluted temperate and cold temperature environments may require the activity of psychrotrophic bacteria, because their low temperature growth range parallels the ambient temperatures encountered in these environments. In the present study, 135 psychrotrophic microorganisms isolated from a variety of ecosystems in Canada were examined for their ability to mineralize 14C-labelled toluene, naphthalene, dodecane, hexadecane, 2-chlorobiphenyl, and pentachlorophenol. A number of the psychrotrophic strains mineralized toluene, naphthalene, dodecane, and hexadecane. None of the psychrotrophs were capable of mineralizing 2-chlorobiphenyl or pentachlorophenol. Those strains demonstrating mineralization activity were subsequently screened by the polymerase chain reaction (PCR) and Southern hybridization of PCR products for the presence of catabolic genes (alkB, ndoB, todCl, and xylE) involved in known bacterial biodegradative pathways for these compounds. Some of the psychrotrophs able to mineralize toluene and naphthalene possessed catabolic genes that hybridized to xylE or todCl, and ndoB, respectively. The alkB PCR fragments obtained from the strains that mineralized dodecane and hexadecane did not hybridize to an alkB gene probe derived from Pseudomonas oleovorans. Psychrotrophic strain Q15, identified as a Rhodococcus sp., also mineralized the C28 n-paraffin octacosane. A gene probe constructed from the "alkB" PCR fragment from strain Q15 did hybridize with the alkB PCR fragments from most of the psychrotrophic alkane biodegraders, indicating that the alkB primers may be amplifying another gene(s), perhaps with low homology to P. oleovorans alkB, which may be involved in the biodegradation of both short chain (dodecane) and longer chain alkanes (hexadecane, octacosane). All of the psychrotrophic biodegradative isolates examined were capable of mineralization activity at both 23 and 5 degrees C, indicating their potential for low temperature bioremediation of petroleum hydrocarbon contaminated sites.

Arthrobacter↗
PubMed1977

The effects of alcohol upon cooling rates of humans immersed in 7.5 degrees C water.

The effects of the ingestion of a moderate dose of alcohol, a known vasodilator, upon the cooling rate of four human subjects immersed in 7.5 degrees C water for periods of time ranging from 38 to 75 min is reported. In three of the cases the cooling rate was retarded, in no case was it accelerated. This result, while lacking statistical significance, has not previously been reported. The difficulties attendant upon such research are noted.

Adult↗
PubMed1990

Characterization of platelet-activating factor receptors in porcine platelets.

Despite a large number of studies describing the properties and effects of platelet-activating factor (PAF), little is known about its receptor structure. The characterization of the PAF receptor from additional cell types and species is important for the design of strategies to purify and characterize the receptor molecule. Porcine platelets were shown to bind PAF with characteristics similar to several other species, based on receptor number, affinity, and the activity of PAF antagonists. We found that the affinity for binding was higher in porcine than in rabbit platelets (Kd = 0.68 +/- 0.13 nM for rabbit and 0.29 +/- 0.10 nM for porcine). Porcine platelets have approximately 281 +/- 158 receptors per cell compared with 689 +/- 229 receptors in rabbit platelets. Rabbit platelets respond to concentrations of PAF that are approximately 10(5)-fold lower than those required for aggregation of porcine platelets, but this difference is probably not due to the differences in receptor number alone. When binding was compared between purified membranes from these two cell types, porcine platelets had 20-fold fewer receptors per milligram of membrane protein, but this difference may have been due to an artifact of the membrane preparation procedure. Binding of PAF was severely hindered at cold temperatures. It was undetectable in whole cells on ice and greatly reduced with purified membranes. This study is the first to characterize PAF receptors in porcine platelets, which represent a potentially useful source of receptor for further biochemical characterization.

Animals↗
PubMed2006

Freeze-thaw increases adeno-associated virus transduction of cells.

A combination of gene and cell-based therapies may provide significant advantages over existing treatments in terms of their effectiveness. However, long-term efficient gene delivery has been difficult to achieve in many cell types, including endothelial cells. We developed a freeze-thaw technique which significantly increases the transduction efficiency of recombinant adeno-associated virus vectors in human aortic endothelial cells (23-fold) and in human renal proximal tubular epithelial cells (128-fold) in comparison to current methods for transduction. Freeze-thaw resulted in a transient but significant increase in cell surface area by 1,174 +/- 69.8 microM2 per cell. Reduction of cryogenic medium volume and repeated freeze-thaw further increased transduction efficiency by 2.8- and 2.4-fold, respectively. Trypsinization, dimethylsulfoxide, and cold temperatures, which are also involved in cell preservation, had no significant impact on transduction efficiency. Increased transduction was also observed in mesenchymal stem cells (42-fold) by the freeze-thaw method. The potential mechanism of this novel technique likely involves an increase in the net permeable area of biological membranes caused by water crystallization. These findings provide a new approach for gene delivery in various cell types, particularly in those resistant to transduction by conventional methods.

Adenoviridae↗
PubMed2002

Involvement of the vagus nerves in the regulation of basal hepatic glucose production in conscious dogs.

We determined if blocking transmission in the fibers of the vagus nerves would affect basal hepatic glucose metabolism in the 18-h-fasted conscious dog. A pancreatic clamp (somatostatin, basal portal insulin, and glucagon) was employed. A 40-min control period was followed by a 90-min test period. In one group, stainless steel cooling coils (Sham, n = 5) were perfused with a 37 degrees C solution, while in the other (Cool, n = 6), the coils were perfused with -20 degrees C solution. Vagal blockade was verified by heart rate change (80 +/- 9 to 84 +/- 14 beats/min in Sham; 98 +/- 12 to 193 +/- 22 beats/min in Cool). The arterial glucose level was kept euglycemic by glucose infusion. No change in tracer-determined glucose production occurred in Sham, whereas in Cool it dropped significantly (2.4 +/- 0.4 to 1.9 +/- 0.4 mg. kg(-1). min(-1)). Net hepatic glucose output did not change in Sham but decreased from 1.9 +/- 0.3 to 1.3 +/- 0.3 mg. kg(-1). min(-1) in the Cool group. Hepatic gluconeogenesis did not change in either group. These data suggest that vagal blockade acutely modulates hepatic glucose production by inhibiting glycogenolysis.

Animals↗