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 37 records · Page 2Linked to original sources
PubMed1994

Effects of nitrogen concentration and cold temperature on DSP-toxin concentrations in the dinoflagellate Prorocentrum lima (Prorocentrales, Dinophyceae).

The diarrhetic shellfish poisoning toxin-producing dinoflagellate, Prorocentrum lima, isolated from Nova Scotian waters, contained both okadaic acid (OA) and dinophysistoxin-1 (DTX-1) throughout its growth cycle in culture; maximum concentrations of toxins and highest OA/DTX-1 ratios occurred during the stationary phase. Cells of P. lima survived 0 degrees C for 5 weeks and recovered when brought to a higher temperature. During the cold period, some cell damage probably occurred with concomitant losses of toxins to the medium. Nitrogen concentration in the medium was used to limit growth or stress the cells physiologically, and when growth was limited, increases in toxin associated with the cells were recorded. The relative amounts of okadaic acid were always greater than dinophysistoxin-1, but the significance of these ratios remains to be determined.

Animals↗
PubMed1995

An rpoE-like locus controls outer membrane protein synthesis and growth at cold temperatures and high pressures in the deep-sea bacterium Photobacterium sp. strain SS9.

Many deep-sea bacteria have evolved specialized adaptations for life at cold temperatures and high pressures. A locus required for both psychro- and baro-adaptation in the psychrophilic, moderate barophile, Photobacterium species strain SS9 was identified among SS9 transposon mutants. DNA sequence analysis of this locus identified four complete open reading frames (ORFs), which appear to comprise an operon, and a fifth incomplete ORF. All transposon insertions isolated are in ORF3. Extensive sequence similarity exists between the translation products of ORFs 1-3 and a collection of gene products proposed to include alternative RNA polymerase sigma factors and modifiers of sigma-factor activity involved in extracytoplasmic sensing and regulation. Based on the similarity between ORF1 and Escherichia coli rpoE, we have tentatively designated this locus the rpoE locus. SS9 rpoE locus ORF3 insertion mutants showed altered abundances of numerous outer membrane proteins and were both baro- and psychro-sensitive. ORF3 mutant revertants that displayed enhanced high-pressure growth also displayed concomitant enhanced low-temperature growth. Most of these revertants possessed DNA rearrangements at the site of the transposon insertion, further demonstrating the importance of the rpoE locus to high-pressure and cold-temperature growth. Complementation analyses indicated that ORF3 functions in OMP synthesis regulation while ORF4 is required for baro- and psychro-adaptation.

Bacterial Outer Membrane Proteins↗
PubMed1998

Lung lining fluid antioxidants in male broilers: age-related changes under thermoneutral and cold temperature conditions.

The purpose of this study was to determine age-related changes in lung lining fluid antioxidants in broilers reared under thermoneutral or cold temperature conditions. Male broilers (Cobb 500) were placed in floor pens within environmental chambers and fed a standard commercial starter diet. The thermoneutral Control chamber was maintained at 32, 30, 27, and 22 to 25 C for Weeks 1, 2, 3, and 4 to 7, respectively, whereas temperature in the Cold chamber was lowered to 18 C during Week 3 and maintained between 15 and 18 C for the rest of the study. At 2, 4, and 7 wk, four to six birds per chamber were selected randomly. The lungs were lavaged with heparinized saline (2 mL/g lung) to obtain lung lining fluid. Antioxidants [reduced (GSH), oxidized (GSSG), and total (TGSH) glutathione, uric acid, ascorbic acid, and alpha- and gamma-tocopherol] in lung lining fluid were determined by HPLC; protein was determined colorimetrically. In Controls, levels of alpha- and -gamma-tocopherol, uric acid, and GSH in lung lining fluid decreased between 2 and 7 wk of age. Birds in the Cold chamber exhibited higher protein, a higher GSSG:TGSH ratio, and a decrease in ascorbic acid (7 wk) in lung lining fluid relative to Controls. Lung lining fluid antioxidants were not correlated with antioxidants in plasma. To determine the effect of vitamin E supplementation on lung lining fluid antioxidants, birds were given a supplement of 200 IU alpha-tocopherol per day for 7 d. Alpha-tocopherol supplementation elevated alpha-tocopherol levels in lung lining fluid, but lowered ascorbic acid, GSH, and GSSG and had no effect on uric acid in lung lining fluid. The results of this study suggest that antioxidant protection in lung lining fluid may diminish with age, that cold conditions in this study produced an oxidative stress in lung lining fluid in broilers, and that oral supplementation of alpha-tocopherol elevated lung lining fluid alpha-tocopherol.

Aging↗
PubMed2000

Expression of fos in the hypothalamus of rats exposed to warm and cold temperatures.

Fos-like immunoreactivity was investigated in hypothalamic areas involved in central thermoregulatory processes. Different groups of urethane anaesthetized rats (n = 36) were exposed to: (1) 23.5 degrees C for 1 h (control); (2) 5 degrees C for 20 min (short cold); (3) 5 degrees C for 1 h (long cold); (4) 47 degrees C for 10 min (short warm) and (5) 47 degrees C for 1 h (long warm). Fos was present in the supramammillary nucleus, supraoptic nucleus and paraventricular hypothalamus of all (control and long and short, warm- and cold-exposed) rats. Fos was seen in the dorsomedial, medial and ventromedial hypothalamus of rats with long or short exposure to both warm and cold temperatures, and in the medial preoptic area and lateral anterior hypothalamus of long and short warm-exposed, and long cold-exposed, rats. Fos was present in the hypothalamus of long and short cold-exposed animals only in the posterior hypothalamus, and in the anterior hypothalamus (central and anterior divisions), suprachiasmatic nucleus and ventrolateral preoptic area of short and long warm-exposed rats. These results provide information on the location of neurons in rat hypothalamus activated by exposure to warm and cold temperatures and may aid in the functional identification of central thermoregulatory pathways.

Animals↗
PubMed1999

Adaptive response to cold temperatures in Vibrio vulnificus.

The effectiveness of rapid chilling or freezing of oysters to reduce Vibrio vulnificus levels in shellfish may be compromised by product handling procedures that permit cold adaptation. When a V. vulnificus culture was shifted from 35 degrees C to 6 degrees C conditions, it underwent transition to a non-culturable state. Cells adapted to 15 degrees C prior to change to 6 degrees C condition, however, remain viable and culturable. In addition, cultures adapted to 15 degrees C were able to survive better upon freezing at -78 degrees C compared with cultures frozen directly from 35 degrees C. Inhibition of protein synthesis by addition of chloramphenicol in a V. vulnificus culture immediately prior to the exposure to the adaptive temperature eliminated inducible cold tolerance. These results suggest that cold-adaptive "protective" proteins may enhance survival and tolerance at cold temperatures. In addition, removal of iron from the growth medium by adding 2,2'-Dipyridyl prior to cold adaptation decreased the viability by approximately 2 logarithm levels. This suggests that iron plays an important role in adaptation at cold temperatures. Analysis of total cellular proteins on an SDS polyacrylamide gel electrophoresis, labeled with 35S-methionine during exposure at 15 degrees C, showed elevated expressions of a 6-kDa and a 40-kDa protein and decreased expression of an 80-kDa protein. These results suggest that, for V. vulnificus, survival and tolerance at cold temperatures could be due to the expression of cold-adaptive proteins other than previously documented major cold shock proteins such as CS7.4 and CsdA. In this study, for the first time we have shown that exposure to an intermediate cold temperature (15 degrees C) causes a cold adaptive response, helping this pathogen remain in culturable state when exposed to a much colder temperature (6 degrees C). This adaptive nature to cold temperatures could be important for shellfish industry efforts to reduce the risk of V. vulnificus infection from consuming raw oysters.

Adaptation, Physiological↗
PubMed1989

Effect of cold temperature on membrane potential responses in opossum esophageal circular muscle.

The effects of cold temperature on resting membrane potential (RMP) and membrane potential responses to depolarizing electrical current and intramural nerve stimulation were examined in opossum esophageal circular smooth muscle. Intracellular recordings were made in smooth muscle strips obtained from 7 to 8 cm (proximal site) and 1 to 2 cm (distal site) above the lower esophageal sphincter. RMP was not affected by changes in temperature between 34 and 22 degrees C. Cooling caused progressive inhibition of the amplitude and a slight increase in the duration of the spike potential produced by depolarizing current. Cooling did not modify the threshold for spike potential generation but decreased the spike amplitude from 34.0 +/- 0.5 mV at 34 degrees C to 14.1 +/- 2.2 mV at 22 degrees C (P less than 0.01). Electrical field stimulation with single electrical pulses (1.0 ms) produced tetrodotoxin-sensitive biphasic membrane responses consisting of initial hyperpolarization, or an inhibitory junction potential followed by depolarization that increased in amplitude as temperature was decreased from 34 to 26 degrees C and then decreased in amplitude as temperature was further decreased. At both proximal and distal sites cooling from 34 to 22 degrees C caused more than a twofold increase in the duration of hyperpolarization and time to peak depolarization. However, the increase in the absolute time of the duration of hyperpolarization and the time to peak depolarization was significantly greater at the distal than proximal esophageal site. Cooling to 16 degrees C decreased RMP and nearly abolished the biphasic membrane potential response.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1995

The Wheat Abscisic Acid-Responsive Protein Kinase mRNA, PKABA1, Is Up-Regulated by Dehydration, Cold Temperature, and Osmotic Stress.

The effects of dehydration, cold-temperature treatment, and osmotic and salt stress on the expression of an abscisic acid-responsive protein kinase mRNA (PKABA1) were determined in wheat (Triticum aestivum L.) seedlings. The PKABA1 transcript was detectable at basal levels in tissues of nonstressed plants and accumulated to higher levels in shoot, scutellar, and root tissues of stressed plants. PKABA1 transcript accumulated rapidly within 2 h following dehydration and within 24 h following other treatments (cold, osmotic stress, and high salt). The accumulation of PKABA1 mRNA could not be separated temporally from that of a wheat group 3 late embryogenesis abundant mRNA during dehydration and cold treatment. High PKABA1 mRNA levels were observed in field-grown plants growing under cold winter conditions but not under warmer summer conditions. A recent GenBank data base search indicated that other plant protein kinases with similar acidic amino acid stretches as in PKABA1 have been identified, and some of these kinases are responsive to environmental signals. These results suggest that PKABA1 may be part of general environmental stress responses in wheat.

Journal Article↗
PubMed1989

The influence of cold temperatures on the progression of hypertension: an epidemiological study.

In order to clarify the relationship between cold temperatures and the progression of hypertension, a prospective epidemiological study was carried out in a cold area of Hokkaido, Japan. We analysed the findings in 909 subjects, who were followed up for 8 years (1977 to 1985). The difference between the mean blood pressure in winter and in summer in the first year was significantly and positively correlated with the difference between the mean blood pressure in the first and in the eighth year. The winter/summer difference was significantly higher in the group with progressive hypertension than in the other groups. The pressor response to exposure to cold was significantly greater in hypertensives, and tended to be higher in borderline hypertensives compared with normotensives. From these results, we conclude that a cold environment might increase the inhabitants' blood pressure levels, and the difference between a subject's blood pressure in winter and summer may predict future hypertension.

Adult↗
PubMed1990

Fructan metabolism in wheat in alternating warm and cold temperatures.

The objective of this research was to develop a system in which the direction of fructan metabolism could be controlled. Three-week-old wheat seedlings (Triticum aestivum L. cv Caldwell) grown at 25 degrees C were transferred to cold temperature (10 degrees C) to induce fructan synthesis and then were transferred to continuous darkness at 25 degrees C after defoliation and fructan degradation monitored. The total fructan content increased significantly 1 day after transferring from 25 degrees C to 10 degrees C in both leaf blades and the remainder of the shoot tissue, 90% of which was leaf sheath tissue. Leaf sheaths contained higher concentrations of fructan and greater portions of high molecular weight fructan than did leaf blades. Fructan content in leaf sheaths declined rapidly and was gone completely within 48 hours following transfer to 25 degrees C in darkness. In leaf blades the invertase activity fluctuated during cold treatment. The activity of sucrose:sucrose fructosyl transferase increased markedly during cold treatment, while fructan hydrolase activity decreased slightly. In leaf sheaths, however, the activity of invertase decreased rapidly upon transfer to cold temperature and remained low. Trends in sucrose:sucrose fructosyl transferase and hydrolase activity in sheaths were the same as those of leaf blades. Sheath invertase and hydrolase activity increased when plants were transferred back to darkness at 25 degrees C, while sucrose:sucrose fructosyl transferase activity decreased. These results indicate that changing leaf sheath temperature can be utilized to control the direction of fructan metabolism and thus provide a system in which the synthesis or degradation of fructan can be examined.

Journal Article↗
PubMed2002

Cold temperature impairs maximal exercise performance in patients with heart failure: attenuation by acute ACE inhibitor therapy.

BACKGROUND: Cold exposure decreases ischemic threshold in patients with coronary artery disease and preserved left ventricle (LV) function. The impact of cold exposure and the effect of acute angiotensin-converting enzyme (ACE) inhibitor therapy on maximal exercise capacity have not been studied in patients with symptomatic congestive heart failure. METHODS AND RESULTS: Eleven patients with New York Heart Association class II and III congestive heart failure, aged 61 6 years (mean SD), with LV ejection fraction 25 6%, completed four symptoms-limited maximal exercise tests at 20 C and -8 C in a cold chamber. The exercise tests were performed while the patients were treated with lisinopril for three days, or a placebo. Cold exposure significantly decreased exercise duration in patients treated with a placebo (506 156 s [20 C] versus 419 182 s [-8 C], P<0.01). Rate-pressure products measured at 4 min during the test and at peak performance were significantly increased at -8 C. Patients treated with lisinopril exhibited a significant attenuation of the decrease in exercise time in the cold (-17% for placebo versus -6.6% for lisinopril, P<0.05). CONCLUSIONS: Cold temperature increases cardiac demand in response to exercise and significantly reduces maximal exercise capacity in patients with symptomatic heart failure. Acute treatment with lisinopril attenuates the impact of cold on exercise capacity.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2003

A thermal adaptation of bacteria to cold temperatures in an enhanced biological phosphorus removal system.

Temperature is one of the key parameters that affects the reaction kinetics and performance of enhanced biological phosphorus removal (EBPR) systems. Although studies agree regarding the effect of temperature on kinetic reaction rates, there are contradictory results in the literature regarding the effect of temperature on EBPR system performance. Early investigators (Sell, Ekama et al., Daigger et al.) reported better performance with lower temperatures, but others have reported partial or complete loss of EBPR functions at low temperatures (McClintock et al., Brdjanovic et a., Beatons et al.). One speculation is that deterioration in the EBPR system performance at cold temperatures can be attributed to rigid-like behavior of the cell membranes. Most cells (not all) on the other hand have the ability to alter their membrane fatty acid composition as temperature changes in order to keep their membrane at nearly the same fluidity despite the temperature changes. This unique ability is known as homeoviscous adaptation. In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20 degrees C to 5 degrees C using a lab scale continuous flow EBPR system fed with acetate and supplemental yeast extract. The fatty acid analysis results suggested that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5 degrees C. The increased cis-9-hexadecanoic acid (C 16:1) at 5 degrees C strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force were operable even at 5 degrees C. It was concluded that loss of EBPR performance at low temperatures is not related to the physical state of the cellular membranes, but is possibly related to the application of unsuitable operational conditions (low SRT, excessive electron acceptors, low anaerobic detention time, non-acclimated sludge, etc.).

Adaptation, Physiological↗
PubMed1996

Characterization of adrenoceptor types and subtypes in American bullfrogs acclimated to warm or cold temperature.

While indirect evidence suggested that the responsiveness of frog adrenoceptors changes in response to temperature, direct measurement of adrenoceptor binding following acclimation to warm and cold temperatures had not been done. In the present study, the radioligands [3H]prazosin, [3H]RX821002, and [125I]cyanopindolol were used to label and quantify alpha 1-, alpha 2-, and beta-adrenoceptors in bullfrogs acclimated to warm or cold environments. The number of alpha 1-, alpha 2-, and beta-adrenoceptors in atrium, ventricle, and kidney membranes was not significantly different between warm- and cold-acclimated frogs. Characterization of receptor subtypes using pharmacological antagonists demonstrated that alpha 2-adrenoceptors in frog spinal cord and kidney were of the same pharmacological subtype, which is similar to the mammalian alpha 2A-subtype. The beta-adrenoceptor in frog ventricle, atrium, and kidney was the beta 2-subtype. These results suggest that while the alpha 1-, alpha 2-, and beta-adrenoceptor types have evolved in the frog, multiple subtypes of adrenoceptors are not necessary for physiological regulation in this species.

Acclimatization↗
PubMed1988

Formation of the high-affinity agonist state of the alpha 1-adrenergic receptor at cold temperatures does not require a G-protein.

Two methods were employed to uncouple hepatic alpha 1-adrenergic receptors from their associated G-protein (termed Gp) in order to determine whether locking of the alpha 1-receptor in a high-affinity agonist state at cold temperatures (2 degrees C) represents formation of a ternary complex. Uncoupling is defined as the inability to observe the GppNHp-sensitive, high-affinity agonist state of the receptor in [3H]prazosin competition binding studies performed at 25 degrees C. The first method for achieving uncoupling involved brief alkalinization and resulted in greater than 95% loss of several G-proteins. The second method involved proteolytic cleavage of either part or all of the alpha 1-receptor coupling domain from the binding domain. Following either treatment, receptors were converted to the high-affinity agonist state at 2 degrees C. Thus, while formation of the high-affinity state of the receptor at higher temperatures may require Gp, formation of this state at 2 degrees C does not require Gp or even the entire alpha 1-adrenergic receptor.

Animals↗