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PubMed1983

Observations on temperature and temperature patterns of the gingiva. I. The effect of arch, region and health.

The purpose of this investigation was to study the pattern and constancy of temperatures recorded in the gingival crevices and some factors affecting them. The temperatures of the interproximal crevices in the maxillary and mandibular arch of 16 female dental hygiene students were evaluated at the time of examination, immediately afterwards and following a 14-day interval. The temperature difference between each site and the subject's sublingual temperature were calculated. In the analysis, a comparison of sites with a confirmed status of bleeding tendency and pocket depth was carried out. The results show temperature differences between arches (mandible vs maxilla) and regions (posterior vs anterior). The differences are independent of the health status. Inflamed gingiva generally has a higher temperature than clinically healthy gingiva. There is an indication that healthy tissue, more than inflamed tissue, reacts to an outside stimulus with an increase in temperature. It is necessary that environmental and stimulative factors are strictly controlled if temperature gradients are to be applied for diagnostic purposes in periodontics.

Adolescent↗

PubMedDate not supplied

Estimation of complete temperature fields from measured transient temperatures.

In hyperthermia treatments, it is desirable to be able to predict complete tissue temperature fields from the limited number of sampled temperatures available. Because of the unknown tissue blood perfusion this is a particularly difficult problem, whose eventual solution will require a considerable effort. An initial attempt to develop methods to solve this problem automatically using unconstrained optimization techniques (which minimize the differences between measured steady-state temperatures and the temperatures predicted from treatment simulations) has been reported previously. A second technique using transient temperatures following a step decrease in power has been developed and is presented and discussed in this paper. The results of applying both it and the steady-state technique to simulated hyperthermia treatments are compared for one-dimensional situations. This transient technique predicts complete temperature fields more accurately and robustly than the steady-state approach. In particular, it can better predict the complete temperature fields in situations where the number of unknown blood perfusion parameters is greater than the number of available temperature sensors.

Chemotherapy, Cancer, Regional Perfusion↗

PubMed1983

The effect of environmental temperature on immune response and metabolism of the young chicken. 3. Effect of environmental temperature on the humoral immune response following injection of sheep red blood cells.

The effect of environmental temperature on the humoral immune response of pullets following injection of sheep red blood cells (SRBC) was investigated. For this purpose four experiments were performed in two climate respiration chambers. In each experiment a standard temperature regimen of constant 25 C was maintained in one chamber. The temperature regimens in the other chamber were as follows: a constant temperature of 15 C (Experiment 1) and 35 C (Experiment 3) and a temperature, which fluctuated between 10 to 20 C (Experiment 2) and between 30 to 40 C (Experiment 4). Total haemagglutinin anti-SRBC antibody titers at Day 5 after injection were increased significantly (P less than .01) at 10 to 20 C, 35 C, and 30 to 40 C compared to the antibody titers of pullets at 25 C. 2-Mercapto-ethanol resistant antibody titers at Day 5 after injection were increased significantly (P less than .05) at 35 C and 30 to 40 C. The effect of feeding level and thermal acclimation on antibody titers was investigated within each temperature regimen. Restricted feeding at low or high temperatures increased antibody titers at Day 5 after injection. Exchange of pullets, just before injection, to low or high temperatures decreased total antibody titers at Day 5 after injection.

Acclimatization↗

PubMed2005

[Study of temperature rise in RF irradiation during MR imaging: measurement of local temperature using a loop phantom].

Cases have been reported of a local rise in temperature at the patient's skin and of burns occurring during MR imaging. To verify this phenomenon, we created a phantom from agarose, saline, and preservative, and measured the increase in local temperature. In addition, phantoms of limbs of the human body shaped such that a closed loop was formed were also used. The temperature of the phantom was measured for 50 minutes in each state, i.e., where a closed loop was formed and where the loop was incomplete. Moreover, the radio frequency (RF) and gradient fields were set as respectively independent states, and the temperature of the phantom was measured. Results of the experiment showed that temperature changed from approximately 6 degrees to 11.5 degrees in the closed loop part of the phantom, whereas there was no significant change when the loop was incomplete. In addition, with exposure to RF, a significant rise in temperature occurred where the loop was closed, whereas there was no significant increase in temperature in gradient fields. This experiment demonstrated that the increase in temperature as a result of RF irradiation occurred in the closed part of the loop phantom. Consequently, a loop formed in the human body may be subject to burns in the area of contact.

Adolescent↗

PubMed1991

Characterization of thermotropism in primary roots of maize: dependence on temperature and temperature gradient, and interaction with gravitropism.

Thermotropism in primary roots of Zea mays L. was studied with respect to gradient strength (degrees C cm-1), temperature of exposure within a gradient, pre-treatment temperature, and gravitropic stimulation. The magnitude of the response decreased with gradient strength. Maximum thermotropism was independent of gradient strength and pre-treatment temperature. The range of temperature for positive and negative thermotropism did not change with pre-treatment temperature. However, the exact range of temperatures for positive and negative thermotropism varied with gradient strengths. In general, temperatures of exposure lower than 25 degrees C resulted in positive tropic responses while temperatures of exposure of 39 degrees C or more resulted in negative tropic responses. Thermotropism was shown to modify and reverse the normal gravitropic curvature of a horizontal root when thermal gradients were applied opposite the 1 g vector. It is concluded that root thermotropism is a consequence of thermal sensing and that the curvature of the primary root results from the interaction of the thermal and gravitational sensing systems.

Gravitropism↗

PubMed1990

Influence of upper and lower thermoneutral room temperatures (20 degrees C and 25 degrees C) on fasting and post-prandial resting metabolism under different outdoor temperatures.

It has been believed that post-absorptive resting metabolic rate (RMR) is invariable provided room temperature is maintained not far from 20 degrees C. Some recent works pose a problem of variability of post-absorptive RMR under conditions of room temperature within the comfortable thermoneutral range; a thermogenic response to mild cold (around 20 degrees C) increases RMR. For a total of 23 male subjects between the ages of 22 and 29 years, determination of post-absorptive and post-prandial RMRs were made after the same subjects wearing standardized clothing stayed overnight on four separate occasions in a room controlled at 20 and 25 degrees C in both winter and summer seasons. RMRs at 20 degrees C in winter were significantly greater by 6-9 per cent than those at 25 degrees C in the same season, and those at 20 degrees C and 25 degrees C in summer. These differences were commonly observed in the post-absorptive RMRs and post-prandial RMRs. No statistical differences were detected among the RMRs on the other three occasions (25 degrees C in winter, 20 degrees C and 25 degrees C in summer). According to a three-way ANOVA, the effects of room temperature, season (outdoor temperature) and time course on RMRs were statistically significant. The effects of room temperature and of season on RMRs were independent of time course, and interacted with each other. These results suggest that 20 degrees C room temperature is not sufficient to determine definite RMR. At the lower room temperature, outdoor temperature is a possible factor that can affect RMRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

[The nature of the dependence of the rate of development on temperature determines the greatest efficiency of metabolism at optimal temperatures].

Metabolism intensity and development rate have different pattern of dependence on temperature. Oxygen intake and several other metabolic processes bear an exponential relationship to temperature. The pattern of this relationship is similar in different poikilothermal species. On the contrary, the relationship between the rate of development and temperature is species-specific and more complex. Hence, the curves obtained by plotting oxygen intake per developmental stage against temperature resemble parabola and the minimum values of oxygen intake correspond to optimal temperatures. Such a correspondence is almost solely determined by parameters of the relationship between the rate of development and temperature. Therefore, the efficiency of metabolism does not determine the range of optimal temperatures. It is suggested that adaptive alterations of this range during evolution proceed via changes of the parameters of relationship between the rate of development and temperature dependence. Relatively small number of mutations is required to produce such changes.

Animals↗

PubMed1986

Effects of the temperature range and the lack of beta-ketoacyl acyl-carrier protein synthase II on fatty acid synthesis in Escherichia coli K12 after shifts in temperature.

Escherichia coli K12 cells grown at higher temperatures and then subjected to lower temperatures produce fatty acids with higher unsaturated/saturated ratios than cells completely adapted to the lower temperatures (Okuyama et al. (1982) J. Biol. Chem. 257, 4812-4817). This hyper-response was not an artefact of chloramphenicol treatment and was observed when the shift-down was more than 20 degrees C in the cells grown at either 40 degrees C or 35 degrees C. In contrast, cells grown at either 25 degrees C or 30 degrees C showed no appreciable hyper-response in terms of unsaturated/saturated ratio on temperature shifts to as low as 10 degrees C. By combining shift-down and shift-up experiments, we could show the presence of different types of temperature dependency in the fatty acid-synthesizing systems of cells grown at various temperatures. Contrary to wild-type cells which synthesized mainly cis-vaccenate on down-shift to 10 degrees C, a mutant strain lacking beta-ketoacyl acyl-carrier protein synthase II synthesized more palmitoleate (16:1) and less palmitate at 10 degrees C than at 40 degrees C. The average chain lengths of saturated and unsaturated fatty acids also changed, but differently, between the mutant and wild-type cells on shifts of temperature. Thus, the mutant strain has a temperature-dependent fatty acid-synthesizing system qualitatively different from that seen in a wild-type strain.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗

PubMed1986

Characterization of DNA replication at a restrictive temperature in a mouse DNA temperature-sensitive mutant, tsFT20 strain, containing heat-labile DNA polymerase alpha activity.

tsFT20 cells derived from a mouse mammary carcinoma cell line FM3A have temperature-sensitive DNA polymerase alpha activity (Murakami, Y., Yasuda, H., Miyazawa, H., Hanaoka, F., and Yamada, M. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 1761-1765). DNA replication in tsFT20 cells at the restrictive temperature (39 degrees C) has been characterized in detail. DNA-synthesizing ability of these cells was measured by [3H] thymidine incorporation and autoradiography. The incorporation of [3H]thymidine decreased rapidly after temperature shift-up, and the incorporation was less than 20% of the initial level after 4 h at 39 degrees C. The rapid decrease correlated well with the decrease in the grain number in the individual nucleus but not with the number of cells with labeled nuclei. Alkaline sucrose gradient sedimentation analysis and DNA fiber autoradiography revealed that DNA chain elongation proceeded normally within a replicon in the temperature-sensitive cells incubated at the restrictive temperature and the DNA elongation rate did not change during the incubation at the restrictive temperature up to at least 6 h. On the other hand, the maturation of replicon-sized DNA to higher molecular weight DNA was retarded or inhibited in the temperature-sensitive cells at the restrictive temperature. The analysis of the center to center distance between replicons by DNA fiber autoradiography revealed that the frequency of replicon initiation decreased in tsFT20 cells at 39 degrees C.

Animals↗

PubMed1985

Minimum temperature felt as hot (MTH)--a new concept for grading the loss of temperature sensation in leprosy patients.

In order to grade the loss of the temperature sensation in the skin of leprosy patients, a newly designed instrument called the Temperature-Sensation-Testing-and-Grading device has been employed to determine the minimum temperature felt as hot (MTH) at the skin area. The MTH in normal subjects was observed to vary from one region of the body to another; it was generally higher on the distal parts of the extremities compared to the proximal parts; and it was also higher on the lower extremities compared to the upper ones. The abdomen and the back generally had the lowest values. There were no variations according to age (11-80 years) or sex and no differences on symmetrical sites of the body. The MTH value, however, showed a dependence on the environmental temperature, the values being lower at low environmental temperatures and higher at high environmental temperatures. But at the same site and the same environmental temperature, the MTH value was found to be almost constant. Different individuals had different MTH values at the same body site and even at the same environmental temperature. The unaffected skin of leprosy patients showed values comparable to the controls. At the leprosy lesions, however, the degree of sensory loss could easily be determined in comparison with the MTH at the contralateral/adjoining unaffected skin. Out of 54 leprosy patients, 7 patients had no sensory loss; in 27 patients the loss varied between 1 degree C and 20 degrees C; while in 20 patients the loss was complete--they could not perceive even 50 degrees C as hot.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Temperature monitoring in the neonate: a comparison of axillary and rectal temperatures.

This study investigated the differences between temperature taking in neonates by the axillary method and by the rectal method. A sample of 46 normal full-term neonates had axillary and rectal temperatures monitored for ten minutes by each method with mercury in glass thermometers. There were significant differences found between axillary and rectal temperatures when compared minute for minute. Stabilized axillary and stabilized rectal temperatures were not tested for difference because axillary temperatures did not meet the criteria for stabilization. A significant positive correlation was found between axillary and rectal temperatures. Axillary temperature taking may be a practical method for neonatal temperature monitoring.

Axilla↗

PubMed1993

Effect of bundling and high environmental temperature on neonatal body temperature.

OBJECTIVE: The effect of bundling and ambient heat on newborn body temperature has not been systematically studied. It was hypothesized that bundling and warm environments can elevate the newborn's temperatures to the range that would prompt clinical concern of neonatal sepsis. METHODS: Twenty well, term newborns more than 1 day old were assigned to the control group (one blanket; 24.0 degrees C room) or the experimental group (five blankets and hat; 26.6 degrees C room). Continuous rectal probe temperatures were monitored over a 2 1/2-hour period. RESULTS: There were 8 control and 12 experimental newborns. The mean change in rectal temperature after 2 1/2 hours was -0.04 degrees C (SD +/- 0.23) in control newborns and +0.56 degrees C (SD +/- 0.12) in the treatment group (P < .0001, t test). Temperatures in the treatment group rose, after an initial half-hour lag, at a linear rate of 0.27 degrees C per hour without a plateau. Two newborns reached 38.0 degrees C, a rectal temperature that may raise concern of infection. CONCLUSIONS: Bundling and warm environments can elevate newborn body temperature to the "febrile" range in this age group. Physicians treating neonates with elevated temperature should ask about bundling and environmental conditions to differentiate endogenous from exogenous "fevers."

Body Temperature↗

PubMed1996

Regional skin temperature, heat flow and conductance in preterm neonates nursed in low and in neutral environmental temperature.

The changes of regional dry heat loss and skin temperature in 15 healthy preterm babies, 8 with a gestational age (GA) of 33-36 weeks and 7 with a GA of 28-31 weeks, were studied under controlled conditions at environmental temperatures ranging from 29.5 to 34.0 degrees C. In both groups of babies the skin temperature for all body regions followed the changes in operative temperatures. Regional dry heat losses also closely followed the external temperature gradient. In the 33-36 weeks GA neonates the regional changes in thermal conductance (index of cutaneous blood flow) indicated that only the foot responded to low environmental temperature with vasoconstriction while vasodilatation was indicated for the trunk. In the 28-31 weeks GA neonates similar but not significant changes of thermal conductance were calculated. The limited ability to reduce heat loss by reducing the skin conductance over a major part of the body surface area contributes to the vulnerability to low environmental temperature in preterm neonates.

Body Surface Area↗

PubMed1990

Does GABA act through dopaminergic/cholinergic interaction in the regulation of higher environmental temperature-induced change in body temperature?

Acute exposure of adult male albino rats to higher ambient temperature (40 degrees C) for 2 h significantly increased body temperature (BT). Administration of either bicuculline (1 mg/kg, i.p.), a GABA antagonist, or physostigmine (0.1 mg/kg, i.p.), an inhibitor of acetylcholinesterase, significantly increased BT of normal and heat-exposed rats. Treatment with muscimol (1 mg/kg, i.p.), a GABA agonist, produced hypothermia in normal rats and prevented an increase in BT of heat-exposed rats. The dopamine agonist, L-dopa (100 mg/kg, p.o.) along with carbidopa (10 mg/kg, p.o.) reduced BT of normal rats. Further, the bicuculline-or physostigmine-induced enhancement of BT in normal and heat-exposed rats was potentiated when both drugs were administered concomitantly. But this potentiating effect remained unaltered when dopamine antagonist haloperidol (1 mg/kg, i.p.) was administered along with bicuculline and physostigmine. Treatment with atropine (5 mg/kg, i.p.), a cholinergic antagonist, abolished the hyperthermic effect of bicuculline but potentiated the hypothermic effect of muscimol either at 28 degrees C or at 40 degrees C. Bicuculline-induced hyperthermia was attenuated at normal or higher temperature by pretreatment with L-dopa + carbidopa. The administration of L-dopa + carbidopa either abolished or reduced the hyperthermic effect of physostigmine at room temperature or at higher ambient temperature. These results suggest that (a) GABAergic, cholinergic and dopaminergic systems are involved in thermoregulation, (b) exposure to high environmental temperature may inhibit central GABAergic activity which activates the cholinergic system without affecting the dopaminergic system and raises BT, (c) central dopaminergic and GABAergic systems act independently through the modulation of cholinergic activity in the regulation of BT under normal ambient temperature.

Animals↗

PubMed1980

Operating room temperature prior to surgical draping: effect on patient temperature in recovery room.

Assessment was made of whether a cold-room environment prior to surgical draping affected patient temperature or the incidence of shivering in the recovery room in patients undergoing major vascular surgery when warming blankets and warmed fluids were used to maintain intraoperative temperature. Forty-two patients scheduled to undergo major vascular surgery were randomly assigned in equal numbers to a "cold or "warm" room. Temperatures in the "warm" rooms were 22.2 C or above (range 22.8-25.6 C) until draping, and in "cold" rooms, 18.9 C or below (ranged 13.9-17.8 C). Once surgical drapes were placed, the room temperature control was set at its minimum, 17 C. All intravenous fluids and blood were warmed to 37.5 C, and a heating blanket was maintained at 37.8 C before and during the operative procedure. Patient temperatures initially did not differ between groups. Despite significantly greater heat loss prior to draping in the cold-room group (0.63 +/- 0.14 C) than in the warm-room group (0.32 +/- 0.10 C) (p < 0.01), there were no differences in temperature in the recovery room, shivering, myocardial, renal CNS, pulmonary, or graft morbidity in the two groups. In major intra-abdominal vascular operations the use of warming blankets and the practice of warming all fluids for infusion allow a comfortable room temperature without detriment to patient care.

Body Temperature↗

PubMed2000

Effect of coupling medium temperature on rate of intramuscular temperature rise using continuous ultrasound.

OBJECTIVE: We determined the effects of coupling medium temperature on the rate of intramuscular temperature rise (RTR) during continuous ultrasound. DESIGN AND SETTING: Ultrasound was applied in a continuous mode at a frequency of 1 MHz and intensity of 1.5 W/cm(2). Each subject received 3 treatments, using water-based coupling gel at temperatures of 18 degrees C, 25 degrees C, and 39 degrees C. All treatments were performed in an athletic training room under controlled environmental conditions. SUBJECTS: Eighteen healthy male subjects (mean age = 23.6 +/- 3.5 years; height = 177.8 +/- 6.9 cm; weight = 76.6 +/- 8.2 kg; calf size = 37.6 +/- 2.4 cm) participated in this study. MEASUREMENTS: A thermistor was inserted into the left medial triceps surae at a depth of 5 cm, and baseline tissue temperatures were recorded before treatment. Intramuscular temperature was recorded every 30 seconds until the temperature rose 4 degrees C above baseline or until discomfort was felt. RTR was calculated by dividing the absolute temperature change by treatment time. RESULTS: A 1-way, repeated-measures analysis of variance revealed a significant difference in RTR among gel temperatures, RTR was significantly faster using the 25 degrees C gel compared with the 18 degrees C and 39 degrees C gels. There was no difference between the 18 degrees C and 39 degrees C gel treatments. CONCLUSIONS: These results suggest that the use of a cooled or heated gel may be counterproductive when maximal thermal effects are desired within a given time frame.

Journal Article↗

PubMed1986

Brain temperature measurements in rats: a comparison of microwave and ambient temperature exposures.

In an effort to understand microwave heating better, regional brain and core temperatures of rats exposed to microwave radiation (2450 MHz) or elevated air temperatures were measured in two studies. In general, we have found no substantial evidence for temperature differentials, or "hot spots," in the brain of these animals. In the first study, after a 30-min exposure, no temperature differences between brain regions either after microwave or ambient air exposure were found. However, a highly significant correlation between brain and core temperatures was found and this correlation was the same for both microwave and ambient air heating. In the second study, time-temperature profiles were measured in rats exposed to either 30 mW/cm2 or 36.2 degrees C. In this study, the 30-min exposure period was divided into seven intervals and the change in temperature during each period was analyzed. Only the cortex showed significantly different heating rates between the air heating and microwave heating; however, this difference disappeared after the initial 5 min of exposure.

Air↗

PubMed1991

1.59 A structure of trypsin at 120 K: comparison of low temperature and room temperature structures.

The structure of a rat trypsin mutant [S195C] at a temperature of 120 K has been refined to a crystallographic R factor of 17.4% between 12.0 and 1.59 A and is compared with the structure of the D102N mutant at 295 K. A reduction in the unit cell dimensions in going from room temperature to low temperature is accompanied by a decrease in molecular surface area and radius of gyration. The overall structure remains similar to that at room temperature. The attainable resolution appears to be improved due to the decrease in the fall off of intensities with resolution [reduction of the temperature factor]. This decreases the uncertainty in the atomic positions and allows the localization of more protein atoms and solvent molecules in the low temperature map. The largest differences between the two models occur at residues with higher than average temperature factors. Several features can be localized in the solvent region of the 120 K map that are not seen in the 295 K map. These include several more water molecules as well as an interstitial sulfate ion and two interstitial benzamidine molecules.

Animals↗