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At least 505 records · Page 28Linked to original sources
PubMed1994

Temperature-dependent absorption/desorption behavior of lower critical solution temperature (LCST) polymers on various substrates.

We have been studying adsorption and retention (resistance to desorption) behavior of temperature sensitive LCST polymers on different substrates as a function of temperature. According to our studies with Poly 64 (a copolymer of 60% (mol) NIPAAm and 40% (mol) NnBAAm, LCST = 8.5 degrees C in water), the copolymer retention depends on the rinse temperature. When the rinse temperature is above the LCST, the polymer adheres well to most surfaces. On the contrary, at rinse temperatures below the LCST, most of the adsorbed polymer is easily rinsed off. These studies are relevant to our work on the thermally reversible adsorption of LCST polymers conjugated to peptides and proteins, such as affinity ligands, for uses in immunoassays and affinity separations. The interaction between the LCST polymer and most hydrophobic polymer surfaces is mainly due to hydrophobic interactions, and the critical surface tension (gamma c) and the solubility parameter (delta) of the solid polymer substrate are the most important factors which influence the LCST polymer adsorption and retention. The critical surface tension appears to correlate best with the LCST polymer adsorption levels on different substrates, while the solubility parameter correlates best with the retention of the adsorbed polymer. According to our preliminary study, n-butyl groups probably interact more strongly with the substrates than isopropyl groups because of the greater hydrophobic surface area of the former groups.

Acrylamides↗
PubMed2025

Construction of cDNA library of Dalbergia odorifera induced by low temperature stress and screening of low temperature tolerant genes.

To systematically analyze the gene function of Dalbergia odorifera, the seedlings of D. odorifera were treated with low-temperature stress for 6 h. Total RNA was extracted from a mixture of seedling roots, stems, and leaves, and a low-temperature-induced D. odorifera yeast cDNA expression library was constructed. The library volume was 1.032 × 108 CFU, and the PCR (Polymerase Chain Reaction) identification of the library bacterial fluid showed that the amplification was around 1000 bp, with a single randomly distributed band, indicating that the library had been recombinantly inserted into the pYES2 vector. The GO (Gene Ontology) analysis showed that the library genes were mainly involved in metabolic and stress signaling pathways. The KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis showed that the genes were primarily related to energy and metabolic pathways. Twenty-one genes were screened or obtained at -20°C for low-temperature tolerance. In addition, the organ expression profiles of the candidate genes were analyzed based on RNA-seq data, and the expression profiles of the candidate genes under low-temperature stress were also examined. The construction of the yeast library provides genetic resources for the analysis of the mechanism of low-temperature tolerance of D. odorifera, which is important for comprehending and utilizing the genetic resources of D. odorifera.

Gene Library↗
PubMed1996

Temperature-dependent sex determination: the interplay of steroid hormones and temperature.

Sex determination is the product of coordinated gene expression. Mutational analyses have yielded great progress in our understanding of mammalian sex determination, and insight into the evolution of this sex chromosome system would be valuable. Mammals arose from turtle-like reptiles, and in many turtles the incubation temperature of the egg determines the sex of the offspring, a process known as temperature-dependent sex determination. There is mounting evidence that sex steroid hormones are the physiological equivalent of incubation temperature and serve as the proximate trigger for male and female sex determination. Temperature appears to accomplish this end by acting on genes coding for steroidogenic enzymes and sex steroid hormone receptors. The ability to manipulate sex determination in turtles both by temperature and by sex steroid hormones extends our understanding of the evolution as well as the physiology and molecular biology of sex determination.

Amino Acid Sequence↗
PubMedDate not supplied

Exercise, performance and temperature control: temperature regulation during exercise and implications for sports performance and training.

Thermoregulation is an important consideration not only for athletic performance but also for the safety of the athlete. This article presents a broad overview of the mechanisms by which body heat is dissipated in an individual exercising in a hot environment. Particularly emphasised are more recent views of body heat loss mechanisms and the influences of non-thermal inputs, such as effects due to changing blood volume or blood flow distribution. During exercise in a hot environment, metabolic heat produced by the exercising muscles is transported by the circulating blood to the surface of the body where it is released to the environment, either by radiation and convection or by evaporation of sweat. The primary drives for both the increased skin blood flow and increased body sweating are the thermal inputs which are sensed by receptors in the deep body core, with a lesser drive from skin receptors. These thermal signals are integrated in the hypothalamus and proper heat loss responses are effected. When exercise is prolonged, however, and body rehydration is not adequate, the total blood volume may be compromised. In addition, as the core temperature increases during exercise, larger proportions of the blood volume are distributed to the cutaneous vessels, thus effectively reducing cardiac return and central blood volume. During severe exercise, a reduction in cardiac filling may result in a fall in central venous pressure and stimulate baroreceptor vasoconstrictor reflexes. As discussed below, the outputs from these baroreceptors compete with and modify the thermal drives for both the control of the skin blood flow and control of the sweat glands. The effect of high ambient temperatures on exercise performance is most evident in prolonged submaximal exercise. Normally, maximal exercise performance is not altered by high temperatures unless the individual has an elevated deep body temperature before the start of the exercise task. However, submaximal exercise performance is often impaired by high ambient temperatures, but may be improved by programmes of physical training and heat acclimatisation. Both training and heat acclimatisation significantly modify the control systems which regulate skin blood flow and sweating. Only acclimatisation programmes, however, are effective in preventing heat stress during prolonged exercise in hot environments.

Animals↗
PubMed1993

Study on the castability of Co-Cr alloy for cast plates. Part 3: Effects of alloy fusion temperature and the heating temperature of the cast ring.

Co-Cr alloy is used more frequently than Ni-Cr alloy as a non-precious alloy for cast plates in Japan. However, since the melting temperature of Co-Cr alloy is very high, about 1300 degrees C, and since it oxidizes easily, a vacuum-pressure casting machine capable of melting this alloy in a reduced atmosphere has recently been developed. Using this machine, the effects of fusion temperature and the heating temperature of the cast ring on the Co-Cr alloy were studied. It was found that in the vacuum-pressure casting method, both the fusion temperature of the Co-Cr alloy and the heating temperature of the cast ring had a significant effect (p < 0.01) on the castability of the Co-Cr alloy.

Chromium Alloys↗
PubMed1987

Effect of temperature on argyrophil impregnation: development of a high temperature rapid argyrophil procedure.

Our studies on the effects of temperature on the demonstration of neurosecretory granules using argyrophil stains indicate an inverse relationship between the time needed for staining and temperature of the silver and reducing solutions. Careful monitoring of the temperature of silver solutions during the Grimelius procedure and its modifications show long incubation times serve in large part only to bring the solutions to reaction temperature. Tissue sections added when this temperature has been reached will stain with the same intensity as sections impregnated for the entire incubation period. We have modified the argyrophil procedure so that double-impregnation with solutions preheated to 60-70 C and development in Bodian's reducer prepared with preheated water rapidly demonstrates secretory granules. Our method does not require a microwave oven and much shorter incubation periods are required than with usual procedures. It is not necessary to incubate sections in hot solutions for extended periods of time, which can lead to detachment of sections, nonspecific staining and decomposition of the silver solution. Rinsing after impregnation and before development greatly increases contrast of argyrophil cells by reducing background staining. Our procedure results in more reliable staining of argyrophil and argentaffin cells and takes only ten minutes.

Adult↗
PubMed1976

Decreases of local brain temperature due to convection (local brain blood flow) and increases of local brain temperature due to activity.

The influence of local brain blood flow upon variations of local brain temperature in chronical experiments was investigated in cats. It was found that changes of local brain temperature in chronic experiments are esclusively due to changes of local metabolic heat production as long as the temperature of brain inflowing blood remains constant. Decreases of temperature due to convection (increase of local blood flow) are smaller than increases of temperature due to activity.

Animals↗
PubMed2000

[Axillary temperature compared to tympanic membrane temperature in children].

The purpose of the study was to measure the axillary temperature at three, six and nine minutes in a hundred children between the ages of one and twelve years who were selected in a non-random deliberate way, and to compare the measurements with the tympanic membrane temperature (golden standard) which was measured in the test persons at the same time. The results were described by sensitivity, specificity, limits of agreement, and predictive values. From some of the findings of the research it is apparent that the axillary temperature reading increased after measurement of three, six and nine minutes. A maximum temperature reading was reached after three minutes in only 9% of the test persons, in 25% after six minutes and in 66% after nine minutes. From the findings it is clear that the ranges that were used influenced the sensitivity of the measurements, and it would appear that the range 35.5 degrees C to 37.2 degrees C was the best range to measure pyrexia in the age group one to 12 years. The 9-minute measurement then had the highest sensitivity. However, the specificity of measurement in this range was lower. The conclusion was drawn that axillary temperature measurement is an acceptable method, with certain reservations, to use as screening method for pyrexia in emergency divisions or clinics.

Age Factors↗
PubMed2003

Suitability of temperature-sensitive transponders to measure body temperature during animal experiments required for regulatory tests.

Body temperature is a clinical parameter in vaccine quality control to detect systemic side-effects or to monitor progression of infectious diseases. Moreover, changes in body temperature are used as clinical parameters to define humane endpoints in animal experiments. However, measuring body temperature via the rectal route can be troublesome and distressing to the animal. Non-invasive measurement methods were developed in recent years. The aim of this investigation was to study and to compare rectally measured body temperature with data obtained with implanted temperature-sensitive transponders (TST) in mice, guinea pigs, rabbits and pigs under the controlled conditions of regulatory testing.

Animals↗
PubMed1978

Cytogenetic studies of a simian virus 40 temperature-sensitive mutant-transformed Chinese hamster cell clone at the permissive and nonpermissive temperature.

A clone of Chinese hamster embryo cells transformed by tsA58, the temperature-sensitive mutant of simian virus 40, was analyzed for chromosome abnormalities at the permissive temperature (37 degrees C) and nonpermissive temperature (40.5 degrees C). Trypsin-Giemsa-banded metaphases were analyzed 1 week after the temperature shift. The metaphases from cells at both temperatures were pseudodiploid, with numerous chromosome changes primarily affecting chromosomes no. 1 and 2. Other chromosomes (no. 6, 11, and the X) were also frequently involved. A marker chromosome, LM, was present in 35% of the cells at 40.5 degrees C.

Animals↗
PubMed1990

Temporal relationships between warmth imagery and associated changes in digital pulse amplitude, skin temperature and skin temperature sensation.

Temporal relationships between warmth imagery and associated psychophysiological changes were studied by recording digital pulse amplitude, skin temperature, and thermal sensations in 5 subjects. After each trial the subjects were asked whether they thought they had been successful in producing the expected mental image. During the subjectively successful imagery tasks the digital pulse amplitude and the skin temperature of the hand rose significantly. The subjective onset of imagery took place after the digital pulse amplitude had started to change but before the skin temperature had begun to rise. This implies that mental imagery of skin warming as a conscious experience is not a prerequisite of somatic change. The thermal sensation (i.e. feeling of warmth) took place while the skin temperature was rising or immediately after that. This suggests that it is not caused by the mental image per se but by activation of skin temperature receptors.

Forearm↗
PubMed1986

Protein kinase-mediated activation of temperature-labile and temperature-stable cholesteryl ester hydrolases in the rat testis.

Both temperature-stable and temperature-labile testicular cholesteryl ester hydrolases are shown to be regulated by an endogenous cAMP-dependent protein kinase activity. The temperature-stable form (Mr = 28,000) was activated 3-fold by the endogenous kinase. This activation was completely blocked by protein kinase inhibitor. Following purification by high performance gel permeation chromatography, the temperature-stable form could also be activated 2-fold by bovine heart protein kinase, type I. The partially purified endogenous protein kinase, type I, which was completely separated from hydrolase activity by ion exchange chromatography, increased hydrolase activity 2-fold in the presence of optimal concentrations of cAMP, ATP, and Mg2+. Cholesteryl ester hydrolase activity could be stabilized indefinitely at -10 degrees C with the addition of 0.1 mM thioglycolate, but not by other thiol reagents. In contrast, the endogenous protein kinase activity was lost from 104,000 X g supernatants after 14 days. However, the property of activation could be restored by addition of bovine heart protein kinase. The temperature-labile hydrolase (Mr = 72,000) could be totally inactivated by a Mg2+-dependent, fluoride-sensitive cytosolic factor and reactivated by cAMP-dependent protein kinase. These observations strongly suggest that the inactivating factor is a phosphoprotein phosphatase.

Animals↗
PubMedDate not supplied

[Nonmonotonous character of temperature changes in protein conformation in predenaturational regions of temperatures].

Temperature changes of protein infrared spectra have a nonmonotonous pattern. On the curves of temperature relationships of spectral characteristics the regions of high frequency displacement have been observed, interrupted by sharp low frequency shifts, partly or entirely compensating the displacement of the bands in the preceding temperature interval. It has been shown that at temperatures corresponding to the high frequency displacement heat weakening of the strength of hydrogen bonds takes place. At the low frequency shifts the whole system of the hydrogen bonds has an opposite change of the state maintaining high stability level of protein macromolecules in the broad temperature range.

Hydrogen Bonding↗
PubMedDate not supplied

The occurrence of ambient temperature-regulated adhesins, curli, and the temperature-sensitive hemagglutinin tsh among avian Escherichia coli.

Escherichia coli establishes a secondary respiratory tract infection in birds following inhalation of contaminated dust and litter particles. Escherichia coli express adhesins under conditions reflective of the ambient temperatures present in poultry houses. These microbial adhesins allow E. coli to attach to cell types that it initially encounters in the respiratory tract. Ambient temperature-regulated adhesins represent a new class of bacterial hemagglutinins that include pili and the thin, aggregative, flexible filaments known as "curli." This study examines the occurrence of the ambient temperature-regulated adhesins, curli (crl, csgA), and an avian-specific, temperature-sensitive hemagglutinin, tsh, among avian and mammalian E. coli isolates. The avian hemagglutinin gene tsh was present in approximately 46% of clinical avian E. coli isolates. This gene was not detected among commensal E. coli isolated from healthy broiler chickens. Unlike tsh, curli genes were ubiquitous among E. coli. However, curli were observed in only half of the avian E. coli examined by electron microscopy. Curli were not present among several nonavian E. coli positive for crl and csgA. Approximately 25% of avian E. coli isolates agglutinated chicken erythrocytes when bacteria were grown at room temperature. Hemagglutination was not specific to E. coli isolated from poultry. Presence of either tsh or curli genes was not indicative of an isolate's ability to agglutinate chicken red blood cells. No discernible structures were observed mediating attachment of the bacteria to chicken red blood cells. An additional avian-specific hemagglutinin appears to be present among avian E. coli.

Adhesins, Bacterial↗
PubMed1976

[Measurement of body temperature in the auditory canal or in the rectum: first experience with a device for continuous registration of body temperature of psychiatric patients (author's transl)].

A method for continuous measurement of body temperature over a 24-h period is presented. the temperature is measured by an active sensor placed in the external auditory canal or in the rectum, and stored on a magnetic tape in a portable cassette recorder weighing 400 g. Rectal temperature is less sensitive to environmental influence and easier to record than ear temperature. With this method possible disturbances of the diurnal temperature rhythm in psychiatric patients can be registered.

Body Temperature↗
PubMed1988

Effects of food temperature and ambient temperature during a meal on food intake in the rat.

Rats kept either at thermoneutrality (29 degrees C) or in the cold (19 degrees C) were fed either at thermoneutrality or in the cold. Rats kept in the cold ingested consistently more food than rats kept at thermoneutrality. Also, independently of nature temperature, rats fed in the cold ingested more food than rats fed at thermoneutrality. There was no interaction between nurture temperature and meal temperature. In a second experiment, rats kept at thermoneutrality were fed food pellets previously warmed or cooled to 12, 29, or 48 degrees C. Food temperature per se had no significant effect on food intake.

Animals↗
PubMed1999

The effects of naked neck genotypes, ambient temperature, and feeding status and their interactions on body temperature and performance of broilers.

The effect of ambient temperature (AT) and feeding status on body temperature (BT) were investigated in broilers of the three naked neck genotypes (Na/Na, Na, na, and na/na). From 29 to 49 d of age, chicks were reared in a temperature-controlled chamber, where AT alternated daily between 24 and 32 C. At Day 47, all birds were deprived of feed for 12 h at 32 C, followed by 12 h of ad libitum intake at 24 C, then 12 h of ad libitum intake at 32 C, and finally feed deprivation for 12 h at 24 C. Body temperature was measured at the end of each of these 12-h periods. Body weight, feed consumption, feather coverage, and breast yield were determined. The Na/na and Na/Na birds had 20 and 40% less feather mass than the na/na birds. The three genotypes had similar BW at Day 49, but the naked neck birds had a higher breast yield. At high AT, BT was positively associated with feather mass of the three naked neck genotypes. The highest BT was exhibited by the fully feathered birds, and the lowest by the homozygous naked neck birds. The feeding status also affected BT of all birds, but to a larger extent in the normally feathered than in the naked neck birds. It appears that the lower negative effects of high AT on growth rate and meat yield in naked neck broilers can be attributed to their lower BT. Thus, it is suggested that measuring BT of broilers can be used as an indicator of the level of stress imposed on them by high AT.

Animal Feed↗