Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cold Climate”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,135 records · Page 63Linked to original sources
PubMed1996

The sensation of respiration in men experiencing high-altitude chronic hypoxia.

Respiratory sensation was studied in seven European lowlanders during a Himalayan expedition at over 6000 m. At rest, the ability to detect added inspiratory resistive loads can be used to create a sensitivity index P(A) taking response bias (B) into account based on Sensory Decision Theory. The data indicate that respiratory sensitivity may be involved in successful adaptation to hypoxia. Respiratory sensitivity improved during the first stages of exposure to altitude and returned to baseline after 17- and 27-day stays under chronic hypoxic conditions. The improvement in respiratory sensation could be a primary signal in the physiological and psychological adaptation to high altitude and change in sensation may reflect the degree of altitude adaptation.

Acclimatization↗
PubMed1994

Parasitic bronchitis in goats and the possible use of Dictyocaulus filaria vaccine for its control.

Parasitic bronchitis is widely prevalent in migratory flocks of small ruminants in the northwest Himalayan regions of India. The prevalence data collected from 5554 goats, maintained in 31 villages in different agroclimatic regions of the Himalayas, showed that the prevalence of the disease in goats varied from 18.7 to 47.6% with an overall prevalence of 21.8%. Interestingly, 27.6% of goats maintained at an altitude of 2700-3900 m above mean sea level in Kargil (Jammu and Kashmir), where the climate is cold and dry for the major part of the year, were positive for the lungworm infections. The common lungworms observed were Dictyocaulus filaria, Protostrongylus rufescens, Varestrongylus pneumonicus and occasionally Muellerius spp. The kids were more susceptible to lungworm infections than adult goats. In experimental studies, it was seen that goats were more susceptible to Dictyocaulus filaria infection than sheep and two vaccine doses comprising 1000 and 2000 gamma-attenuated D. filaria (ovine strain) infective larvae conferred 97% protection in male Beetal kids against a homologous challenge dose of 4200 normal D. filaria larvae. The importance of simultaneous control of the disease in goats and sheep is discussed.

Animals↗
PubMed1978

Blood glycoprotein from antarctic fish. Possible conformational origin of antifreeze activity.

High resolution 1H NMR and circular dichroism (CD) measurements have been performed on aqueous solutions of antarctic fish antifreeze glycoprotein. The carbohydrate contribution ot the observed CD spectrum has been estimated from closely analogous model compounds. The residual peptide contribution cannot be interpreted of the known spectral behaviour of alpha-helix, beta-sheet and random coil. Instead it resembles the CD spectrum of beta-structure in position, magnitude and spectral form, but is of opposite sign, indicating a specific but unusual peptide conformation, which we suggest may be stabilised by non-bonded interactions between the peptide backbone and the carbohydrate sidechains. Previous evidence which supports this interpretation is reviewed. NMR and CD measurements between -2 and +30 degrees C are consistent with conformational stability throughout the biologically relevant temperature range. The mechanism of the antifreeze activity is discussed in terms of the spatial and orientational correlations of sugar hydroxy groups and water in the liquid and solid states. The implication of an ordered peptide structure is explained by the comparison of the antifreeze glycoprotein with synthetic water-soluble polymers which also exhibit limited antifreeze properties.

Animals↗
PubMed1983

A comparative study of protein synthesis in nototheniids and icefish at Palmer Station, Antarctica.

Protein synthetic rates were measured in tissues of Notothenia corriceps, N. gibberifrons and Chaenocephalus aceratus in vivo at 2 degrees C by a method in which high doses of 14C-phenylalanine are used for stabilization of specific radioactivity. Rates in N. coriiceps, as per cent of tissue protein synthesized per day, were: liver 10.4, head kidney 3.5, testis 2.6, spleen 2.1, kidney 1.9, gill 1.6, heart 1.4, pectoral muscle 1.0, epaxial muscle 0.37, brain 0.42. With the exception of liver and head kidney (9.8 and 3.4, respectively) all rates in the icefish C. aceratus were significantly reduced compared to the nototheniids, consistent with the dependence of protein synthesis on oxidative metabolism. Icefish lack hemoglobin in the blood. The effects of two-week starvation were tissue-specific. Rates declined markedly in pectoral and epaxial muscle, were unchanged in liver, kidney, brain, heart and testis, and were increased in gill and head kidney. The results are discussed in relation to cold adaptation of Antarctic fishes and to the adaptation of metabolism required during non-feeding periods and for species which lack an oxygen-binding pigment in their blood.

Animals↗
PubMed1983

Antifreeze glycopeptides of antarctic fishes.

A method is described for analysis of amino acid composition and concentration of antifreeze glycopeptides of Antarctic fish by automatic amino acid analysis of hydrolyzed samples purified by trichloroacetic acid fractionation. Preparations were 98% pure and showed characteristic alanine, threonine and proline compositions. Analyses were carried out in 17 known species of Ross Sea, Antarctica, fishes and in 11 undescribed species tentatively placed in genera, where possible, or families. Collections have been preserved for classification. The results provide evidence of species specificity in amino acid composition and plasma concentration of these substances. Closely related species showed nearly identical Pro/Ala ratios, but differing concentrations. The results do not support reclassification of Trematomus and Notothenia into a single genus or the inclusion of the genus Pleuragramma in the family Nototheniidae. Data obtained for developing ovaries of 6 species showed concentrations of these substances (per unit wet wt) about one-half those of plasma and similar, but not identical, amino acid compositions to those of plasma. The total amount in eggs was 4 times that of plasma in pre-spawning individuals. Calculations are presented to indicate the role of these substances in the protein metabolic economy of the animal for Nototheniidae and Channichthyidae.

Amino Acids↗
PubMed1985

Hybrid protein synthetic systems: components required to confer poikilothermy to the mammal.

Temperature dependency of homologous and heterologous protein synthetic cell-free systems reveals characteristic homeotherm and poikilotherm behavior depending on the source of the enzyme elongation factor 1 and not on any other protein synthetic components. The results for rat and Antarctic fish, when compared with previous studies in eurythermal fish and mammals provide the explanation for the phenomenon of true hibernation in animals such as ground squirrels and woodchucks. The killing of these rare animals can now be stopped by granting agencies that support hibernation research. Comparison of temperature effects on laboratory rats and wild rats indicate a need for wild rat research directed toward eradication of these pests in cities. Suggestions are made for this purpose.

Amino Acyl-tRNA Synthetases↗
PubMed1988

Vitamin D metabolism in polar vertebrates.

1. Studies of serum 25-hydroxy-vitamin D (25-OHD) in the Antarctic have been undertaken in husky dog, seal and penguin and compared to man. 2. Husky dogs showed a reversal of the expected seasonal variation of serum 25-OHD with maxima in June when the hours of bright sunshine and amount of u.v. -B radiation were lowest. 3. Values for random serum 25-OHD values in seals showed large interspecies differences, the values for Weddell seals being significantly greater than for Crabeater seals (P less than 0.01). 4. Penguin sera showed low concentrations of serum 25-OHD with no evidence of a response to prolonged exposure to sunlight.

Adult↗
PubMed1987

Occult carbon monoxide poisoning: a cause of winter headache.

Headache is an early symptom of carbon monoxide (CO) poisoning, occurring at carboxyhemoglobin (COHb) levels of greater than 10%. We investigated 37 patients presenting to an emergency department during the winter-heating season with a complaint of headache for evidence of CO exposure. Seven of the 37 patients (18.9%) had COHb levels in excess of 10%, with a mean of 14.0%. Three of these seven patients (42.9%) used gas space heaters or kitchen stoves to heat their homes, and three (42.9%) had cohabitants at home with headache. Of the 30 patients with COHb levels of less than 10% (mean level, 3.2%), only four (13.3%) used gas space heaters and kitchen stoves for heat (P = NS), and none (0%) had cohabitants with headache (P = .0045). In six of the seven patients with elevated COHb levels (85.7%), gas company investigation or historical information obtained retrospectively revealed a definite or probably toxic CO exposure. In none of these patients had the diagnosis of CO poisoning been suspected by the emergency department physician or the patient prior to obtaining the result of the COHb level. Occult CO poisoning may be an important cause of winter headache.

Adolescent↗
PubMed1984

Comparative studies on superoxide dismutase and catalase activities in livers of fish and other Antarctic vertebrates.

The activities of superoxide dismutase and catalase in livers of fish and other Antarctic vertebrates were examined. Significant differences between superoxide dismutase activities in livers of white-blooded and red-blooded fish species were observed. Superoxide dismutase seems to be involved more than catalase in protection processes against cell damage caused by oxygen free radicals.

Animals↗
PubMed1988

Wind-chill and the seasonal variation of cerebrovascular disease.

The hospital admission rates for patients with specific types of stroke were examined for seasonal variation and correlation with meteorological factors. A seasonal variation in admission rates was found for subarachnoid haemorrhage, thrombo-embolic brain infarction and ill-defined cerebrovascular disease. Overall this seasonality was more strongly associated with the computed chilling effect of the atmosphere than with changes in temperature, humidity or wind speed alone. No seasonal variation was observed for admission rates of intracerebral haemorrhage, transient ischaemic attack or occlusion of precerebral arteries. Intracerebral haemorrhage admission rates exhibited a decrease with time. This evidence suggests that seasonal variation in admission rates exists only for certain pathological types of stroke and this is strongly associated with changes in the chilling effect of the atmosphere.

Adult↗
PubMed1995

Ice-based altitude distribution of natural radiation annual exposure rate in the Antarctica zone over the latitude range 69 degrees S-77 degrees S using a pair-filter thermoluminescence method.

Both ice-based altitude distributions of natural ionizing radiation exposure and the quasi-effective energy of natural radiation over Antartica over the latitude range 69 degrees S - 77 degrees S during approx. 500 days were measured using thermoluminescent dosimeters. The results shows that dependence on altitude above sea level of the exposure rate increases by almost three-fold with each increase of 2000 m of altitude, thus deviating from the general rule stating that the exposure rate should double with each 2000 m. Although the exposure rate shows a dependence on altitude, altitude dependence of the quasi-effective energy of natural radiation over Antartica is not observed. In the present study it is observed that natural radiation occurring over the ice base of Antartica consists mainly of cosmic rays.

Altitude↗
PubMed1979

Microbiological flora as a function of ice depth in central Antarctica.

A technique has been developed for obtaining ice samples under sterile conditions for microbiological analyses as a function of ice thicknesses and with a view to clarifying the possibility of long term microbial anabiosis under permafrost conditions. For the first time microbiological studies from the surface down to 312 meters in the Vostok station region have been carried out and the distribution of microorganisms in the strata studied has been clarified. Microorganisms occur rather rarely, and their distribution is of a random character, independent of the depth of sampling. Viable microorganisms have been found in the ice horizons approximately as old as 8-13 thousand years.

Antarctic Regions↗
PubMed2006

Flexibility and enzymatic cold-adaptation: a comparative molecular dynamics investigation of the elastase family.

Molecular dynamics simulations of representative mesophilic and psycrophilic elastases have been carried out at different temperatures to explore the molecular basis of cold adaptation inside a specific enzymatic family. The molecular dynamics trajectories have been compared and analyzed in terms of secondary structure, molecular flexibility, intramolecular and protein-solvent interactions, unravelling molecular features relevant to rationalize the efficient catalytic activity of psychrophilic elastases at low temperature. The comparative molecular dynamics investigation reveals that modulation of the number of protein-solvent interactions is not the evolutionary strategy followed by the psycrophilic elastase to enhance catalytic activity at low temperature. In addition, flexibility and solvent accessibility of the residues forming the catalytic triad and the specificity pocket are comparable in the cold- and warm-adapted enzymes. Instead, loop regions with different amino acid composition in the two enzymes, and clustered around the active site or the specificity pocket, are characterized by enhanced flexibility in the cold-adapted enzyme. Remarkably, the psycrophilic elastase is characterized by reduced flexibility, when compared to the mesophilic counterpart, in some scattered regions distant from the functional sites, in agreement with hypothesis suggesting that local rigidity in regions far from functional sites can be beneficial for the catalytic activity of psychrophilic enzymes.

Acclimatization↗