Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TEMPERATURE”

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 163 records · Page 9Linked to original sources

Identification of Low-temperature-regulated ORFs in the cyanobacterium Anabaena sp. strain PCC 7120: distinguishing the effects of low temperature from the effects of photosystem II excitation pressure.

Most organisms have developed various strategies to react rapidly to temperature down-shift and regulate expression of various genes to acclimate to low temperature. In photosynthetic organisms, temperature down-shift in the light results in not only a decrease in growth temperature but also an increase in PSII excitation pressure. Distinguishing the effects of low temperature from the effects of excitation pressure is necessary to understand the mechanism of low-temperature signal transduction. In this report, we analyzed changes in gene expression after three different environmental changes, i.e. temperature down-shift in the light, temperature down-shift in the dark and transfer to the dark, using DNA microarray in the cyanobacterium Anabaena sp. strain PCC 7120. By comparing the expression patterns under the three experimental conditions, we identified 15 open reading frames (ORFs) that were up-regulated by temperature down-shift both in the light and in the dark. These ORFs are considered to be regulated by low temperature, but not by excitation pressure. Six of them have a consensus sequence within the upstream region of their coding region and were indicated also to be up-regulated by tetracycline. Functional or structural changes in the ribosome could affect transcript levels of the low-temperature-regulated ORFs.

Anabaena↗

Temperature dependence of inorganic nitrogen uptake: reduced affinity for nitrate at suboptimal temperatures in both algae and bacteria.

Nitrate utilization and ammonium utilization were studied by using three algal isolates, six bacterial isolates, and a range of temperatures in chemostat and batch cultures. We quantified affinities for both substrates by determining specific affinities (specific affinity = maximum growth rate/half-saturation constant) based on estimates of kinetic parameters obtained from chemostat experiments. At suboptimal temperatures, the residual concentrations of nitrate in batch cultures and the steady-state concentrations of nitrate in chemostat cultures both increased. The specific affinity for nitrate was strongly dependent on temperature (Q10 approximately 3, where Q10 is the proportional change with a 10 degrees C temperature increase) and consistently decreased at temperatures below the optimum temperature. In contrast, the steady-state concentrations of ammonium remained relatively constant over the same temperature range, and the specific affinity for ammonium exhibited no clear temperature dependence. This is the first time that a consistent effect of low temperature on affinity for nitrate has been identified for psychrophilic, mesophilic, and thermophilic bacteria and algae. The different responses of nitrate uptake and ammonium uptake to temperature imply that there is increasing dependence on ammonium as an inorganic nitrogen source at low temperatures.

Bacteria↗

Tympanic membrane temperatures compared to rectal and oral temperatures.

One hundred thirty-seven children at the Cleveland Clinic Foundation were enrolled in a study comparing the accuracy and acceptability of tympanic membrane temperatures taken with Thermoscan to rectal or oral temperatures taken by IVAC electronic thermometers. The mean age of the rectal/ear group was 1.2 +/- 0.86 years (range 0.08-5.0 years) with 22 females and 21 males. The mean age of the oral and ear group was 9.0 +/- 4.24 years (range 3-18 years) with 44 females and 50 males. Significantly large (p less than 0.01) correlation coefficients were present between temperatures in the left ear and right ear (0.92), rectal and mean ear (0.77) and oral and mean ear (0.68). The temperature difference between mean ear and rectal measurements was -1.1 degree +/- 0.51 degree C and the temperature difference between the mean ear and oral measurements was -0.20 degrees +/- 0.59 degrees C. A relative lack of correlation between ear and oral temperatures was noted with flat tympanograms, otoscopically diagnosed middle ear effusion, and with red-white or red tympanic membranes. However, small subgroup sizes (6-16) may have contributed to this lack of correlation. Parents and physicians were impressed by the 2.5 second speed of the new technique. However, younger children were nearly as likely to resist and cry with ear as with rectal temperatures. Parents were comfortable with the ease, cleanliness and safety of ear temperatures. While these data indicate a strong correspondence of ear temperatures with oral and rectal temperatures, parents were not as confident of ear temperatures' accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Effects of an advanced temperature cycle on smolt development and endocrinology indicate that temperature is not a zeitgeber for smolting in Atlantic salmon.

Atlantic salmon (Salmo salar) juveniles were reared under simulated conditions of normal photoperiod (LDN) or short days (LD 9:15) and ambient temperature (AMB: normal temperature increases in April) or an advanced temperature cycle (ADV: temperature increases in February). Under both photoperiod conditions, the timing of increased and peak levels of gill Na(+),K(+)-ATPase activity were not altered by temperature, although the rate of increase was initially greater under ADV. ADV/LD 9:15 resulted in peak gill Na(+),K(+)-ATPase activity that was half of that seen under normal photoperiod and temperature conditions. Plasma growth hormone (GH) levels increased threefold in late March under ADV/LDN, but not under ADV/LD 9:15, indicating that there is a photoperiod-dependent effect of temperature on levels of this hormone. Plasma insulin-like growth factor I (IGF-I) increased in spring in all groups, with increases occurring significantly earlier in the ADV/LDN group. In each photoperiod condition, the advanced temperature cycle resulted in large decreases in plasma thyroxine (T(4)) levels in March, which subsequently recovered, whereas plasma 3,5,3'-triiodo-L-thyronine (T(3)) levels were not substantially affected by either photoperiod or temperature. There was no consistent pattern of change in plasma cortisol levels. The results do not provide support for the role of temperature as a zeitgeber, but do indicate that temperature has a role in the timing of smolting by affecting the rate of development and interacting with the photoperiod.

Animals↗

Influence of temperature on growth of Legionella pneumophila biofilm determined by precise temperature gradient incubator.

Bacterial growth is influenced by several different culture conditions. Temperature is one of an essential component which regulates bacterial growth and their morphology. The influence of temperature on the length of bacteria was investigated in broth and on agar in a temperature range from 30.0 degrees C to 47.0 degrees C in 0.5 degrees C steps using a newly developed temperature gradient incubator. The incubator is able to reach a set temperature within 2 h and maintain temperature as accurate as +/-0.1 degrees C of the set temperature. Three Legionella pneumophila serotype 1 strains were incubated for 48 h in BCYE-alpha agar at various temperatures ranging from 30.0 degrees C to 48.0 degrees C and length of bacteria grown at each temperature was microscopically measured. Ability of bacteria to multiply at a given temperature was also determined. L. pneumophila serotype 1 strains ATCC 33152, a clinical isolate Okinawa 02-001 were going to elongate to longer than 100 mum when cultured higher than at 39.5 degrees C and at 41.5 degrees C, respectively. Each strain was unable to multiply when cultured higher than at 44.2 degrees C (ATCC 33152) or at 44.0 degrees C (Okinawa 02-001). Those data would provide insights for establishing regulations in terms of maintaining hot water temperature in a facility where a circulating hot water supply-system is available and contamination with Legionella spp. is likely to happen.

Adaptation, Physiological↗

Airway narrowing measured by spirometry and impulse oscillometry following room temperature and cold temperature exercise.

STUDY OBJECTIVE: The efficacy of using impulse oscillometry (IOS) as an indirect measure of airflow obstruction compared to spirometry after exercise challenges in the evaluation of exercise-induced bronchoconstriction (EIB) has not been fully appreciated. The objective was to compare airway responses following room temperature and cold temperature exercise challenges, and to compare whether IOS variables relate to spirometry variables. DESIGN: Spirometry and IOS were performed at baseline and for 20 min after challenge at 5-min intervals. SETTING: Two 6-min exercise challenges, inhaling either room temperature (22.0 degrees C) or cold temperature (- 1 degrees C) dry medical-grade bottled air. At least 48 h was observed between these randomly assigned challenges. PARTICIPANTS: Twenty-two physically active individuals (12 women and 10 men) with probable EIB. INTERVENTIONS: Subjects performed 6 min of stationary cycle ergometry while breathing either cold or room temperature medical-grade dry bottled air. Subjects were instructed to exercise at the highest intensity sustainable for the duration of the challenge. Heart rate and kilojoules of work performed were documented to verify exercise intensity. MEASUREMENTS AND RESULTS: Strong correlations were observed within testing modalities for post-room temperature and post-cold temperature exercise spirometry and IOS values. Spirometry revealed no differences in postexercise peak falls in lung function between conditions; however, IOS identified significant differences in respiratory resistance (p < 0.05), with room temperature-inspired air being more potent than cold temperature-inspired air. CONCLUSIONS: Correlations were found between spirometric and IOS measures of change in airway function for both exercise challenges, indicating close equivalency of the methods. The challenges appeared to elicit the EIB response by a similar mechanism of water loss, and cold temperature did not have an additive effect. IOS detected a difference in degree of response between the temperatures, whereas spirometry indicated no difference, suggesting that IOS is a more sensitive measure of change in airway function.

Adult↗

Relationship between mean body surface temperature measured by use of infrared thermography and ambient temperature in clinically normal pigs and pigs inoculated with Actinobacillus pleuropneumoniae.

OBJECTIVE: To determine the relationship between ambient temperature and mean body surface temperature (MBST) measured by use of infrared thermography (IRT) and to evaluate the ability of IRT to detect febrile responses in pigs following inoculation with Actinobacillus pleuropneumoniae. ANIMALS: 28 crossbred barrows. PROCEDURES: Pigs (n = 4) were subjected to ambient temperatures ranging from 10 to 32 C in an environmental chamber. Infrared thermographs were obtained, and regression analysis was used to determine the relationship between ambient temperature and MBST. The remaining pigs were assigned to groups in an unbalanced randomized complete block design (6 A pleuropneumoniae-inoculated febrile pigs [increase in rectal temperature > or = 1.67 C], 6 A pleuropneumoniae-inoculated nonfebrile pigs [increase in rectal temperature < 1.67 C], and 12 noninoculated pigs). Infrared thermographs and rectal temperatures were obtained for the period from 2 hours before to 18 hours after inoculation, and results were analyzed by use of repeated-measures ANOVA. RESULTS: A significant linear relationship was observed between ambient temperature and MBST (slope, 0.40 C). For inoculated febrile pigs, a treatment X method interaction was evident for rectal temperature and MBST, whereas inoculated nonfebrile pigs only had increased rectal temperatures, compared with noninoculated pigs. A method X time interaction resulted from the longer interval after inoculation until detection of an increase in MBST by use of IRT. CONCLUSIONS AND CLINICAL RELEVANCE: Infrared thermography can be adjusted to account for ambient temperature and used to detect changes in MBST and radiant heat production attributable to a febrile response in pigs.

Actinobacillus Infections↗

Influence of water bolus temperature on measured skin surface and intradermal temperatures.

Temperature measurements utilizing thermometry probes placed on the skin surface are often used clinically to assess temperatures for the purposes of power control and evaluating treatment efficacy. There is a question, however, as to what extent applicator temperature-controlled liquid coupling boluses can create temperature gradients which can cause significant differences between measurements taken by sensors placed on the skin surface and the actual temperature of the tissue beneath. To address this question, experiments were conducted with human subjects instrumented with surface and shallowly implanted temperature sensors. Microwave applicators with circulating bolus water set at 21 and 41 degrees C were used to induce a temperature gradient in depth in the superficial tissue by thermal conduction. No microwave energy was applied. The average measurement offset at 41 degrees C was 15% of the difference in temperature between the interstitially measured skin temperature and the coupling bolus temperature, towards the temperature of the coupling bolus. The corresponding offset with coupling boluses set near 21 degrees C was 32%. Different water bolus types and volumes were observed to induce different percentage offset errors.

Connective Tissue↗

Effect of ambient temperature on brain temperature and sleep-wakefulness in medial preoptic area lesioned rats.

The changes in brain temperature and sleep-wakefulness were studied in rats during their exposure to different ambient temperatures of 18 degrees C, 24 degrees C and 30 degrees C, before and after N-methyl D-aspartic acid lesion of the medial preoptic area. The medial preoptic area lesion produced a decrease in sleep, and increase in brain temperature except at 30 degrees C. Increase and decrease in brain temperature with slow wave sleep and paradoxical sleep respectively, were observed both in normal and lesioned rats. Sleep-wakefulness and brain temperature cycle durations were increased and their frequencies decreased at higher ambient temperature in normal rats. After the medial preoptic area lesion, sleep-wakefulness cycle duration was decreased and frequency increased at 30 degrees C. There was no significant change in brain temperature cycles at higher ambient temperature in lesioned rats. The medial preoptic area, in normal rats, possibly interlinks the neuronal circuits involved in regulating brain temperature and sleep-wakefulness cycles. The medial preoptic area is essential for increasing the sleep-wakefulness cycle duration with higher ambient temperature. The possible contribution of the increased brain temperature variation in producing sleep-wakefulness changes cannot be ruled out. The results of the study show that this area may serve as a fine tuning mechanism which helps to interlink the sleep-wakefulness with the thermoregulation.

Analysis of Variance↗

[Temperature dependence of kinetic parameters of single potential dependent K+ channels in mollusc neurons. Similarity in the action of potential and temperature].

Using the patch-voltage-clamp method on excised membrane fragments from molluscan neurones temperature dependences of kinetic parameters of the fast and slow K(+)-channels were investigated in the temperature range 1 to 40 degrees C. Temperature dependences of probability of the channel open state (P0) for the slow and fast K(+)-channels are, generally, opposite, that is P0 increases for the slow channel and decreases for the fast channel with temperature. Similar dependences characterize durations of single channel open intervals (tau 0) and burst durations (t(p)). Durations of interburst and interpulse intervals (respectively, t(i) and tau) decrease for the slow channel and increase, in contrast, for the fast channel with temperature. For the channels of both types temperature dependences of P0 (as for other parameters) are essentially nonmonotonous. There are two local extrema, at least: for the slow K(+)-channel-maximum at 15 degrees C (minimum for the fast channel) and minimum at 20-25 degrees C (maximum for the fast channel). In some cases the number of local extrema may be greater than two. Some similarity in the action of temperature and membrane potential on the kinetic parameters was observed. For the slow K(+)-channel P0, tau 0 and t p increase with temperature and membrane potential. For the fast channel these parameters decrease at the same conditions. Moreover, for the channels of both types temperature dependences of the kinetic parameters are slightly pronounced at the potentials where potential dependences of the parameters are least. As a whole, temperature measurements showed that there are, possibly, several points of structural transitions (similar to phase transitions) in the temperature range 0 to 40 degrees C. Primarily, the kinetic parameters are determined by these transitions.

Animals↗

Body temperature in the Nigerian neonate--comparison of axillary and rectal temperatures.

Body temperature was measured in 104 healthy full-term neonates of appropriate weights using the rectal and axillary routes simultaneously at 1, 2, 3, 5 and 7 min after placement of the thermometer. Normal body temperature in the Nigerian newborn, irrespective of the site where it was obtained, ranged from 35.9 degrees C to 37.5 degrees C. There was a strong positive correlation between axillary and rectal temperatures (r = 0.9). Prior to stabilization, mean rectal temperatures at every minute were significantly higher than axillary temperatures, (P less than 0.001). Although rectal temperatures stabilized earlier than axillary temperatures (3 min and 5 min respectively), the difference between mean stabilized temperature taken at the two sites was not significant (P greater than 0.05). This study provides normal reference data on body temperature in the Nigerian newborn. It is suggested that the axillary route be used more frequently when taking temperature in the newborn because of its safety and its good correlation with the rectal temperature readings.

Axilla↗

[Behavior of central venous blood temperature in short duration and repeated stress--possibilities for temperature controlled frequency-adapted pacemaker stimulation].

Although an exercise-induced increase in blood temperature has been well-known for some time, there was still some doubt whether the change in central venous blood temperature with short-lasting and repetitive physical exercise can be measured and utilized by a temperature controlled pacing system. We studied the central venous blood temperature with short-lasting and repetitive exercise in ten healthy young volunteers and in ten pacemaker patients. The blood temperature was measured intracardially while they walked upstairs. A height of 20 m was covered within 100 +/- 5 s. An oxygen uptake of 27 ml/min/kg was calculated for this level of exercise. After walking upstairs once, the volunteers had an increase in central venous blood temperature of 0.3 degrees C and the pacemaker patients of 0.37 degrees C. After walking upstairs three times, the volunteers had an overall rise in blood temperature of 0.67 degrees C and the pacemaker patients of 0.86 degrees C. Thus, the central venous blood temperature shows a pronounced, measurable increase with short-lasting exercise as well. However, the rises in blood temperature accumulate with repetitive exercise, as the duration of exercise (100 s) when walking upstairs once is not sufficient for a new level of temperature to be reached according to the level of exercise. Thus, a temperature controlled pacing system should take these complex changes into consideration.

Adult↗

Effects of room temperature, seasonal condition and food intake on finger skin temperature during cold exposure test for diagnosing hand-arm vibration syndrome.

For diagnosing the hand-arm vibration syndrome, peripheral circulation and sensory tests immersing one hand in cold water at 10 degrees C for 10 min have been performed widely in Japan. The authors investigated the effects of room temperature, seasonal condition and food intake on the test results, especially finger skin temperature. Six healthy males were examined repeatedly under six different room temperatures at 10 degrees C, 15 degrees C, 20 degrees C, 22.5 degrees C, 25 degrees C and 30 degrees C. Eight healthy males were examined under room temperatures at 10 degrees C, 20 degrees C and 30 degrees C, repeatedly in winter, spring, summer and autumn. Six healthy males were examined in summer under room temperature at 22.5 degrees C repeatedly 1 hr after, 3 hr after meal and after fasting for 13 hr. The finger skin temperature was strongly affected by room temperature. The finger skin temperature was also affected by seasonal condition. No remarkable effect of food intake was observed. For estimating circulatory function of the upper extremities using the finger skin temperature, the room temperature should be strictly controlled and the effect of seasonal condition must be taken into consideration.

Adult↗

Relation between the melting temperature and the temperature of maximum density for the most common models of water.

Water exhibits a maximum in density at normal pressure at 4 degrees above its melting point. The reproduction of this maximum is a stringent test for potential models used commonly in simulations of water. The relation between the melting temperature and the temperature of maximum density for these potential models is unknown mainly due to our ignorance about the melting temperature of these models. Recently we have determined the melting temperature of ice I(h) for several commonly used models of water (SPC, SPC/E, TIP3P, TIP4P, TIP4P/Ew, and TIP5P). In this work we locate the temperature of maximum density for these models. In this way the relative location of the temperature of maximum density with respect to the melting temperature is established. For SPC, SPC/E, TIP3P, TIP4P, and TIP4P/Ew the maximum in density occurs at about 21-37 K above the melting temperature. In all these models the negative charge is located either on the oxygen itself or on a point along the H-O-H bisector. For the TIP5P and TIP5P-E models the maximum in density occurs at about 11 K above the melting temperature. The location of the negative charge appears as a geometrical crucial factor to the relative position of the temperature of maximum density with respect to the melting temperature.

Journal Article↗

Effects of atmospheric humidity and acclimation temperature on the temperature response of photosynthesis in young Larix decidua Mill.

Larch (Larix decidua Mill.) seedlings of a low altitude (600 m) Austrian provenance were raised outdoors and acclimated in chambers for 14 to 24 days during August and September at either 8 degrees C and an atmospheric saturation vapor pressure deficit (DeltaW) of 2.5 Pa kPa(-1), or 24 degrees C and a DeltaW of 6.2 Pa kPa(-1). Subsequently, their rates of photosynthesis, dark respiration and transpiration were measured at temperatures between 5 and 30 degrees C with DeltaW either maintained below 10 Pa kPa(-1) or allowed to increase with temperature up to 38 Pa kPa(-1). Below 15 degrees C the photosynthetic rate of cold-acclimated plants was higher, but above 15 degrees C it was lower, than that of warm-acclimated plants. Temperature acclimation caused a greater shift in the temperature optimum for photosynthesis when DeltaW was kept small than when it was allowed to increase with temperature. When DeltaW was kept small, leaf conductance of cold-acclimated plants, unlike that of warm-acclimated plants, did not increase with temperature above 15 degrees C. When DeltaW increased with temperature, leaf conductance of cold-acclimated plants decreased more rapidly with temperature than that of warm-acclimated plants. Low temperature acclimation increased the rate of photosynthesis below 15 degrees C without affecting leaf conductance, which indicates that there was an adaptation in leaf internal processes. Further evidence of a metabolic adaptation to acclimation temperature is that dark respiration of cold-acclimated plants was twice that of warm-acclimated plants at all temperatures.

Journal Article↗

Effect of low temperature on microbial growth: lowered affinity for substrates limits growth at low temperature.

The effect of environmental temperature on the affinity of microorganisms for substrates is discussed in relation to measurements of affinity by either K(s) values or specific affinity (a(A)). It can be shown for psychrophiles, mesophiles and thermophiles that when a(A) is used as the measure of affinity, affinity decreases consistently as temperature drops below the optimum temperature for growth. This effect may be because of stiffening of the lipids of the membrane below the temperature optimum, leading to decreased efficiency of transport proteins embedded in the membrane. The lower temperature limit for growth is, therefore, that temperature at which an organism is no longer able to supply the maintenance requirement of the growth rate-limiting nutrient because of loss of affinity for that substrate. This linking of temperature and affinity for substrates taken up by active transport (a temperature-modulated substrate affinity model) includes uptake of both organic and inorganic substrates. This effect of decreased substrate affinity at low temperature may have profound implications on the availability of substrates in the natural environment as environmental temperatures change. At temperatures below their optimum for growth microorganisms will become increasingly unable to sequester substrates from their environment because of lowered affinity, exacerbating the anyway near-starvation conditions in many natural environments.

Journal Article↗

Is axillary temperature an appropriate surrogate for core temperature?

The ideal technique for measuring temperature should be rapid, painless, reproducible and accurately reflect the core temperature. While axillary temperature is commonly used because of convenience and safety, there are conflicting reports about its accuracy. To determine whether axillary temperature can act as a surrogate for oral/rectal temperatures, a prospective comparative study was conducted. The axillary and rectal temperatures (Group 1: infants < 1 year age) and axillary and oral temperatures (Group 2: children 6-14 years age) were compared using mercury-in-glass thermometers. Various tests of agreement were applied to the data obtained. Rectal and axillary temperatures for infants agreed well; the mean difference (95% limits of agreement) between the two being 0.6 degree C (-0.3 degree C, 1.4 degrees C). Similarly, the mean difference (95% limits of agreement) between oral and axillary measurements for children aged 6-14 years was observed to be 0.6 degree C (-0.4 degree C, 1.4 degrees C). Axillary temperature appears to be an acceptable alternative to rectal/oral temperature measurements in children.

Adolescent↗

Administration of fenfluramine at different ambient temperatures produces different core temperature and 5-HT neurotoxicity profiles.

This study investigated the effect of two different ambient temperatures on fenfluramine-induced 5-HT neurotoxicity. Fenfluramine (FEN) (12.5 mg/kg x 4; injections made hourly) or saline (SAL) was administered to rats in either a normal laboratory temperature of 24 degrees C or a warm environment of 30 degrees C. Animals were kept at that ambient temperature for 20 h after FEN administration. Ambient temperature was controlled to +/-0.5 degrees C and rat core temperature was continually measured using a non-invasive apparatus. FEN-treated rats at 24 degrees C displayed a core temperature hypothermia with a peak low of 33.8 degrees C, and this core temperature hypothermia lasted for 20 h after FEN administration. Rats treated with FEN at 30 degrees C displayed a significant core temperature hyperthermia for 4 h after the first drug injection compared to SAL-treated groups, with a peak core temperature of 38.6 degrees C. 2 weeks after FEN injections, brain regions were analyzed by HPLC. Both groups of FEN-treated rats showed decreases in 5-HT and 5-HIAA in the hippocampus, frontal cortex, somatosensory cortex, striatum, hypothalamus and septum. However, FEN rats treated at 30 degrees C had significantly greater decreases (26-35%) in 5-HT compared to FEN-treated rats at 24 degrees C in the frontal cortex, hippocampus, striatum and somatosensory cortex and significantly greater decreases (26-50%) in 5-HIAA in the frontal cortex, hippocampus and somatosensory cortex. This study indicates fenfluramine can produce neurotoxicity in rats that display either a core temperature hypothermia or hyperthermia, although hyperthermic rats have greater 5-HT and 5-HIAA depletions than the hypothermic rats.

Animals↗