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At least 415 records · Page 23Linked to original sources
PubMed1995

Response of the bvg regulon of Bordetella pertussis to different temperatures and short-term temperature shifts.

Bordetella pertussis produces a number of virulence factors whose expression is coordinately regulated by the bvgAS locus. Transcription of virulence genes is repressed by environmental factors such as low temperature (25 degrees C) and chemical stimuli. Temperature shift of bacterial cultures from 25 degrees C to 37 degrees C activates two classes of bvg-regulated virulence genes: the early genes, which are activated within 10 min, and late genes, which require 2-4 h for activation. During the interval between the activation of the early and late genes, the intracellular concentration of BvgA increases 50-fold. It has been proposed that this increased concentration may be required for the activation of the late genes. Here we have analysed the response of the bvg locus to intermediate temperature and to repeated temperature shifts. Temperature shifts of B. pertussis cultures from 22 degrees C to 28 degrees C or 35 degrees C resulted in the synthesis of low, intermediate, and high amounts of BvgA. This implied that the intracellular concentration of BvgA is temperature-dependent. We have also observed that the amount of virulence factors produced correlates with the BvgA concentration. When bacteria grown at 37 degrees C were shifted to 22 degrees C, transcription from the adenylate cyclase toxin haemolysis promoter (PAC) was repressed after 30 min, while transcription from the bvg (P1) and filamentous haemagglutinin (PFHA) promoters was repressed after 2 h. During this time, the amount of BvgA did not decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗
PubMed1982

Deep scrotal temperature and the effect on it of clothing, air temperature, activity, posture and paraplegia.

Two new techniques for measuring deep scrotal temperature are described. Paraplegic men in wheelchairs have deep scrotal temperatures averaging about 0.9 degrees C higher than normal sitting men, and those whose scrotal temperatures are very high usually lack motile spermatozoa. In the author, deep scrotal temperatures at constant air temperature are 0.5 degrees C lower wearing boxer shorts than wearing Y-fronts, and 1.2 degrees C lower wearing scrotal slit underpants than wearing boxer shorts; they are 1.6 degrees C lower sitting with thighs apart than sitting with thighs together, and 0.5 degrees C lower running than sitting with thighs apart. From such observations, means of lowering paraplegic deep scrotal temperatures can be designed.

Air↗
PubMedDate not supplied

The effects of elevated temperatures and various time-temperature combinations on the development of Brachiola (Nosema) algerae N. Comb. in mammalian cell culture.

Nosema algerae Vávra and Undeen 1970, a microsporidian known to cause infection in mosquitoes, develops in mammalian cell cultures at 24-35 degrees C and in the tails and footpads of athymic mice. More recently it has been reported to grow at 38 degrees C in human cell culture. The present study is a two-part temperature/development examination. The first part examines the development of N. algerae in rabbit kidney cell culture at 29 degrees C, which permits the formation of functional spores within 72 h, and compares the effect of elevated temperatures (36.0, 36.5, 37 degrees C) on parasite development. At these elevated temperatures, N. algerae infects but undergoes only one or two proliferative divisions, with no evidence of sporogony by 72 h post-inoculation. During this time, however, the host cells continue to divide resulting in fewer infected cells over time and giving the appearance of a diminished parasitemia. Additionally, at 37 degrees C some organisms degenerate/hibernate by 72 h while others remain viable/active. It is not until 96 h that the parasites appear in large clusters of proliferative stages in the few host cells that are infected. By 120 h post-inoculation, proliferative cells, sporoblasts, and early spores are observed. These results suggest that elevated temperatures impede proliferation rates and the onset of sporogony. The second part of this study evaluates developmental changes in N. algerae when incubation temperatures and times are varied during parasite growth, resulting in abnormal parasite morphology. These abnormalities were not present when parasites were grown at constant temperature (29-37 degrees C). This report demonstrates that N. algerae can successfully develop at high temperatures (37 degrees C), justifying its taxonomic relocation to the genus Brachiola.

Animals↗
PubMed1978

Temperature stress and immunity in mice: effects of environmental temperature on the antibody response to human immunoglobulin of mice, differing in age and strain.

Physiological responses at different ambient temperatures and temperature-dependent changes in immune responsiveness are polymorphic. At 4 degrees C, the antigen elimination from the bodies of SJL and C57Bl/6 mice is accelerated. In SJL, but not in C57Bl/mice, the half-life of antigen elimination decreased between the ages of 3 and 11 weeks. Parental mice and their F1 hybrids showed a fall in rectal temperature, which was greatest in young animals. Hypothermia was greater in C57Bl/6 than in SJL and F1 hybrids; in 3 week old C57Bl/6 it resulted in high mortality. The response to aggregated human immunoglobulin (HGG) was evaluated by (a) the number of animals with detectable antibody, (b) the minimal dose of antigen eliciting detectable antibody, and (c) the mean titre of haemagglutinating antibody. SJL mice were more responsive than C57Bl/6 mice. Low antibody formation in the secondary response was dominant, i.e. the amount of antibody produced by (SJL X C57Bl/6)F1 mice was the same as that produced by the parental C57Bl/6 strain. In a primary response, the quantity of antibody varied with the age of the immunized animal; 18 week old mice responded to lower minimal doses of antigen and produced more haemagglutinating antibody than 3 week old animals. After a second injection with HGG, SJL but not C57Bl/6 mice produced more antibody when kept at 14 degrees C rather than at 22 degrees C or 30 degrees C, and produced the lowest antibody titres when kept at 4 degrees C. The relation between ambient temperature and the response of the SJL mice was dominant over that of the C57Bl/6strain. Primary differed from secondary responsiveness in that neither strain produced significantly lower titres when ambient temperature fell to 4 degrees C; only 18 week old SJL mice responded with a marginal decrease in peak antibody production. The described polymorphism may affect both the individual capacity to cope with low temperatures and the evolutionary adaptation of a species to climatic extremes.

Age Factors↗
PubMed1987

Evaluation of electrical conductivity-temperature curves using a mathematical model: temperature-dependent changes during thawing of frozen aqueous pharmaceuticals.

The information contained in the electrical conductivity curves of pharmaceuticals measured as a function of temperature can be represented by a small set of parameters. This is achieved by approximating the electrical conductivity curve as a number of consecutive steps, using a suitable empirical model. The three parameters describing each step are: transition temperature, slope factor and step height. The validity of the calculated transition temperatures was established by applying the model to electrical conductivity curves measured on aqueous solutions of KCl, NaCl and on a KCl-NaCl mixture. It appears that the transition temperatures calculated for these inorganic salts are in good agreement with the respective eutectic temperatures reported in the literature. Subsequently, the method was applied to the corticosteroids prednisolone sodium succinate and prednisolone disodium phosphate. The mathematical model yields a satisfactory fit for both experimental conductivity curves. The actual consequences of freeze-drying an aqueous solution of prednisolone sodium succinate below and above the respective transition temperatures calculated are discussed in relation to the experimental conductivity data.

Chemistry, Pharmaceutical↗
PubMed1980

Temperature-sensitive mutants of influenza A virus: transfer of the two temperature-sensitive lesions in the Udorn/72-ts-1A2 virus to the A2Hong Kong/123/77 (H1N1) wild-type virus.

The influenza A/Udorn/72-ts-1A2 virus possesses temperature-sensitive mutations in the genes coding for the P1 and P3 polymerase proteins. It is being evaluated as a donor of its attenuating temperature-sensitive genes to produce recombinant live vaccine strains of epidemic variants of influenza A virus. Transfer of the P1 and P3 genes to two viruses within the H3N2 subtype of influenza A virus (i.e., the A/Victoria/3/75 and A/Alaska/6/77 viruses) conferred on each variant the following properties: (i) 37 degrees C shutoff temperature for plaque formation, (ii) almost complete restriction of viral replication in the lungs, (iii) a 100-fold restriction of viral replication in the nasal turbinates, and (iv) genetic stability after replication in hamsters. This study was undertaken to determine whether the transfer of the two ts-1A2 temperature-sensitive genes into a virus belonging to the H1N1 subtype (i.e., the A/Hong Kong/123/77 virus) would result in a restriction of replication in vitro and in vivo comparable to that observed with the previously studied H3N2 recombinant viruses in hamsters. This was found to be the case. In addition, infection of hamsters with the A/Hong Kong/77-ts-1A2 virus induced significant resistance to infection with wild-type A/Hong Kong/77 virus. Thus, the two ts-1A2 temperature-sensitive genes attenuated influenza A viruses belonging to two distinct subtypes to a specific and predictable level. An unexpected genetic interaction was observed between several A/Hong Kong/77-ts-1A2 segregants bearing the group 5 (P1) temperature-sensitive lesion. One interpretation of these results is that intracistronic complementation occurred between these segregants.

Animals↗
PubMed1979

Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli.

When protein synthesis was blocked in temperature-sensitive deoxyribonucleic acid synthesis mutants of Escherichia coli at nonpermissive temperatures, it reduced the amount of apparent subsequent chain elongation to approximately half that observed in the mutants either at nonpermissive temperatures alone or when protein synthesis was blocked at the permissive temperature. Blocking protein synthesis at the nonpermissive temperatures for periods of 40 min caused the loss of ability to reinitiate deoxyribonucleic acid synthesis at the permissive temperature.

Amino Acids↗
PubMed1986

Developmental temperature and life span in Drosophila melanogaster. II. Oscillating temperature.

Alternating developmental temperature within the viable range 13-33 degrees C, with increasing amplitude around a mean value of 23 degrees C but constant period (2 days, a 1 day/1 day rhythm), resulted in increased duration of development, decreased body weight and decreased growth rate of both male and female flies. Life span of female flies also decreased with increasing amplitude of temperature of oscillation but that of males increased (compared to that at the mean temperature) at moderate temperature amplitude. Variation of the period of oscillation (from a rhythm of 6 h/6 h up to 2 days/2 days) with constant amplitude (23 +/- 5 degrees C), on the other hand, did not affect either duration of development or body weight of the flies. However, life span of the females only was unaffected but that of males was increased (above that at mean constant temperature 23 degrees C) at the fast oscillation patterns (6 h/6 h and 1 day/1 day). Finally, life span of both sexes was positively correlated with growth rate in the constant period/varying amplitude case, whereas in previous studies variation of growth rate in the same range by other means showed a biphasic or an invariant pattern of life span dependence on growth rate. These results are in agreement with the hypothesis of epigenetic influence on life span by alternating developmental temperature and corroborate the previous conclusion that growth rate per se does not determine life span.

Animals↗
PubMed2007

Temperature-dependent effects of cadmium and purine nucleotides on mitochondrial aconitase from a marine ectotherm, Crassostrea virginica: a role of temperature in oxidative stress and allosteric enzyme regulation.

Temperature and heavy metals such as cadmium (Cd) are important environmental stressors that can strongly affect mitochondrial function of marine poikilotherms. In this study, we investigated the combined effects of temperature (20 degrees C and 30 degrees C) and Cd stress on production of reactive oxygen species (ROS) and oxidative stress in a marine poikilotherm Crassostrea virginica (the eastern oyster) using mitochondrial aconitase as a sensitive biomarker of oxidative damage. We also assessed potential involvement of mitochondrial uncoupling proteins (UCPs) in antioxidant protection in oyster mitochondria using purine nucleotides (GDP, ATP and ADP) as specific inhibitors, and free fatty acids as stimulators, of UCPs. Our results show that exposure to Cd results in elevated ROS production and oxidative damage as indicated by aconitase inactivation which is particularly pronounced at elevated temperature. Unexpectedly, oyster mitochondrial aconitase was inhibited by physiologically relevant levels of ATP (IC(50)=1.93 and 3.04 mmol l(-1) at 20 degrees C and 30 degrees C, respectively), suggesting that allosteric regulation of aconitase by this nucleotide may be involved in regulation of the tricarboxylic acid flux in oysters. Aconitase was less sensitive to ATP inhibition at 30 degrees C than at 20 degrees C, consistent with the elevated metabolic flux at higher temperatures. ADP and GDP also inhibited mitochondrial aconitase but at the levels well above the physiological concentrations of these nucleotides (6-11 mmol l(-1)). Our study shows expression of at least three UCP isoforms in C. virginica gill tissues but provides no indication that UCPs protect mitochondrial aconitase from oxidative inactivation in oysters. Overall, the results of this study indicate that temperature stress exaggerates toxicity of Cd leading to elevated oxidative stress in mitochondria, which may have important implications for survival of poikilotherms in polluted environments during seasonal warming and/or global climate change, and suggest a novel temperature-dependent mechanism of allosteric regulation of TCA flux in oyster mitochondria.

Aconitate Hydratase↗
PubMed2006

Overexpression of heat shock protein 70 restores the structural stability and functional defects of temperature-sensitive mutant of large T antigen at nonpermissive temperature.

The effects of heat shock protein 70 (Hsp70), a molecular chaperone, on the degradation and functional alterations of a mutant large T antigen induced by a nonpermissive temperature were examined. In this study, mouse tracheal epithelial TM02-3 cells harboring temperature-sensitive simian virus 40 large T antigen and stable TM02-3 cells overexpressing human Hsp70 and/or Hsp40 were used. Although the temperature shift from 33 degrees C (permissive temperature) to 39 degrees C (nonpermissive temperature) induced increases in the endogenous chaperones including Hsp70 and Hsp40, degradation of the T antigen, activation of the p53-p21(waf1) pathway, and an arrest of cell growth were observed in the mock cells. In contrast, these changes induced by the temperature shift were partially but significantly prevented in stable cells overexpressing human Hsp70 and/or Hsp40. A combination of Hsp70 and Hsp40 was the most effective, suggesting that Hsp40 may cooperate with Hsp70. Moreover, immunocytochemical observation indicated that human Hsp70 was expressed in the cytoplasm at 33 degrees C, but it colocalized with T antigen in the nucleus at 39 degrees C. These results suggest that overexpressed Hsp70 translocates from the cytoplasm to nucleus, and significantly restores the structural stability and functional defects of mutant large T antigen in the cells.

Animals↗
PubMed1977

[Fluctuation and distribution of animal room temperature and the temperature in cages (author's transl)].

The temperature of various positions in an occupied animal room (mice, rats) including inside of cages were measured using a 50 channels thermal data recorder (step time 0.5 sec, 5 min intermittent through 24 hr and continuous) in a summer day. Any short periodical fluctuation of room temperature had practically no influence on the inside temperature of plastic cages. Against small diurnal fluctuations, stable vertical gradients (about 1 degree C between tops and bottoms of racks) were observed among one hour averages of room air temperatures. Air temperature in the cage fluctuated in larger scale. (up to 3 degrees C) For controlling animal room temperature, each of short periodical fractuation, diurnal change and spasal distribution should be separately concerrned.

Animals↗
PubMed1996

Temperature and non-aromatizable androgens: a common pathway in male sex determination in a turtle with temperature-dependent sex determination?

This study addressed the hypothesis that, in the red-eared slider turtle, Trachemys scripta, non-aromatizable androgens are the physiological equivalent of temperature in determining male development. In the first experiment, eggs were treated in the middle of the temperature-sensitive period with 1.0 or 10.0 micrograms androsterone, 5 alpha-dihydrotestosterone, 3 alpha-androstanediol, or 3 beta-androstanediol, while at an all-male, male-biased, or one of two female-biased incubation temperatures. In the second experiment, eggs were treated with the same dosages of dihydrotestosterone at different stages of embryonic development while at a male-biased, threshold, or a female-biased incubation temperature. Results of experiment one indicated that hormone-induced masculinization is specific to non-aromatizable androgens. Results of experiment two indicated that the sensitivity to dihydrotestosterone corresponds to the temperature-sensitive window during development. Further, there is a dose-response relationship but no apparent synergism between exogenous dihydrotestosterone and incubation temperature. When considered with other research, it is suggested that non-aromatizable androgens and their products are involved in the initiation of male sex determination whereas oestrogens and their aromatizable androgen precursors are involved in the initiation of female sex determination.

Androstane-3,17-diol↗
PubMed2002

Light-dependent changes in the chick pineal temperature and the expression of cHsp90 alpha gene: a potential contribution of in vivo temperature change to the photic-entrainment of the chick pineal circadian clock.

The circadian clock is entrained to the diurnal alteration of environmental conditions such as light and temperature, but the molecular mechanism underlying the entrainment is not fully understood. In the present study, we employed a differential display-based screening for a set of genes that are induced by light in the chick pineal gland, a structure of the central clock entrainable to both light and temperature changes. We found that the level of the mRNA encoding chicken heat shock protein 90 alpha (cHSP90 alpha) was rapidly elevated in the pineal gland within a 5-min exposure of chicks to light. Furthermore, the pineal cHsp90 alpha mRNA was expressed rhythmically under both 12-hr light/12-hr dark (LD) cycles and constant dark (DD) conditions. The total amount of the pineal cHSP90 alpha protein was, however, kept at nearly constant levels under LD cycles, and immunohistochemical analyses of the pineal cHSP90 alpha showed invariable localization at the cytoplasm throughout the day. In vivo measurement of the chick pineal temperature demonstrated its light-dependent and time-of-day-dependent change, and the profile was very similar to that of the pineal cHSP90 alpha mRNA level. These observations suggest that the in vivo temperature change regulates the expression of temperature-responsive genes including cHSP 90 alpha in the pineal gland. The temperature change may induce a phase-shift of the pineal clock, thereby facilitating its efficient entrainment to environmental LD cycles.

Animals↗
PubMed1996

The effect of temperature mishandling at various times during storage on detection of temperature abuse of fresh broiler chicken carcasses.

Experiments were conducted to determine the effect that temperature mishandling at various times during storage has on detection of temperature abuse of fresh broiler chicken carcasses using populations of mesophilic and coliform bacteria as indicators of abuse. Forty-five broiler carcasses were used in each of three independent trials. Five carcasses were analyzed at day of collection (Treatment 0 control). Five carcasses, on each day of the next 7 d (Treatments 1 to 7) were temperature-abused for 12 h at 25 C, stored at 3 C until Day 9, and then sampled. The five remaining carcasses were stored at 3 C and sampled on Day 9 (Treatment 8 control). Carcasses were sampled using a whole carcass rinse procedure and assayed for aerobic plate counts (APC), total coliform counts (TCC), impedance detection times (DT), and impedance coliform detection times (DTCM). Although significant differences were noted using all four microbiological methods, temperature abuse at different times during storage had no consistent effect on populations of mesophilic or coliform bacteria; therefore, temperature abuse determinations may be conducted without regard to the day on which the carcasses were subjected to elevated temperatures.

Animals↗
PubMed2000

Core temperature measurement during supine exercise: esophageal, rectal, and intestinal temperatures.

BACKGROUND: The purpose of this study was to characterize intestinal temperature (T(in)) in comparison to esophageal (T(es)) and rectal temperature (T(re)) during supine exercise. METHODS: Seven subjects completed a continuous supine protocol of 20 min of rest, 20 min of cycle exercise at 40% peak oxygen consumption (V(O2peak)), 20 min of cycle exercise at 65G% V(O2peak), and 20 min of recovery. T(es), T(re), and T(in) were recorded each min. RESULTS: Temperatures were not different after 20 min of rest, but T(es) and T(in) were greater than T(re) at the end of the 40% (T(es): 37.38 +/- 0.11; T(in): 37.35 +/- 0.06; T(re): 37.20 +/- 0.10 degrees C) and 65% V(O2peak) stages (T(es): 37.83 +/- 0.10; T(in): 37.75 +/- 0.05; T(re): 37.63 +/- 0.08 degrees C). After 20 min of recovery, T(es) (37.24 +/- 0.011 degrees C) was less than either T(re) or T(in), which were not different from each other (T(in): 37.39 +/- 0.09; T(re): 37.44 +/- 0.09 degrees C). Time to threshold for increased temperature from rest (+0.10 degrees C) for T(es) (10.0 +/- 1.1 min) was not different from T(in) (14.0 +/- 1.2 min) but less than T(re) (15.7 +/- 1.6 min). Time to reach peak temperature was less for T(es) (36.6 +/- 1.8 min) than T(in) (40.6 +/- 0.9 min) and T(re) (41.4 +/- 0.5 min). Similarly, time to a decrease in temperature (-0.10 degrees C) after exercise was less for T(es) (3.7 +/- 0.4 min) than T(in) (7.1 +/- 1.5 min) and T(re) (10.6 +/- 1.9). CONCLUSIONS: Measurement of T(in) may be an alternative to T(es) to measure T(core) specific time points during exercise with an understanding of the slower response of Tin compared with T(es).

Adult↗
PubMed1999

[Temperature effect and temperature gradient technology in capillary electrophoresis].

A review is given here to describe the temperature effect and temperature gradient technology in capillary electrophoresis (CE). The temperature effects on the analysis of DNA, protein peptides and amino acids, enantiomers, carbohydrates and other substances are discussed respectively. The theory of temperature effect is also mentioned. The importance of the temperature gradient in CE, the classifications of gradient technology in CE, the potential applications and different method development of the temperature gradient are described. Fifty-one references are cited.

Amino Acids↗
PubMed2004

[The temperature and temperature gradients distribution in the rabbit body thermophysical model with evaporation of moisture from its surface].

On created in laboratory heat-physical model of a rabbit body reflecting basic heat-physical parameters of the body such as: weight, size of a relative surface, heat absorption and heat conduction, heat capacity etc., a change of radial distribution of temperature and size was found across a superficial layer of evaporation of water from its surface, that simulates sweating, with various ratio of environmental temperature and capacity of electrical heater simulating heat production in animal. The experiments have shown that with evaporation of moisture from a surface of model in all investigated cases, there is an increase of superficial layer of body of a temperature gradient and simultaneous decrease of temperature of a model inside and on the surface. It seems that, with evaporation of a moisture from a surface of a body, the size of a temperature gradient in a thin superficial layer dependent in our experiments on capacity for heat production and environmental temperature, is increased and can be used in a live organism for definition of change in general heat content of the body with the purpose of maintenance of its thermal balance with environment.

Animals↗
PubMed1989

[Can measurement of oral or axillary temperature replace rectal temperature measurements?].

The Craftemp thermometer is an electrical device for measurement of oral and axillary temperatures. The applicability of this thermometer in clinical practice was investigated by comparison with rectal temperatures measured with a mercury thermometer. Ninety-five patients hospitalized in a medical department participated in the study. The median differences between rectal/oral and rectal/axillary temperatures were 0.8 degrees C and 1.2 degrees C, respectively. The range of the extrarectal measurements was unacceptably wide. In previous studies of the Craftemp thermometer, few investigators performed the temperature measurements on hospitalized patients and found the electrical thermometer usable. In the present investigation the measurements were performed by the permanent staff during their daily routine. It was concluded, that the oral and axillary temperatures measured with an electrical thermometer were unsuitable for determination of body temperature in patients hospitalized in a medical department.

Adult↗