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At least 685 records · Page 38Linked to original sources
PubMed1989

[Local hyperthermia using a device made of temperature-sensitive ferrite. The first report: temperature, output characteristics].

The basic study of intracavitary and interstitial hyperthermia was made with the Soft-Heating Method. In this method, a hybrid device composed of non-magnetic metal ring and ferrite rod is used as a heater. Being exposed to external magnetic field, the device produces heat, and its temperature rises to the Curie Temperature of the ferrite rod with self-regulation. The accuracy of the regulation is +/- 0.2 degrees C near the Curie Temperature which can be set up almost freely. In addition to that, the frequency of magnetic field is not so high (20-50 KHz) that there is no damping nor reflection of the field in a human body. Therefore the system seems to be very useful for hyperthermia of deep seated tumor. In this paper, experimental discussion of the possibility of local hyperthermia by the system is made. From the results, it is concluded that the system will be applied to clinical uses.

Animals↗
PubMed1978

On the formation of rho - petites in yeast. III. Effects of temperature on transmission and recombination of mitochondrial markers and on rho - cell formation in temperature sensitive mutants of Saccharomyces cerevisiae.

The rho-factor stability is shown to be affected by four conditional mutations, tsm-8 (mitochondrial), tsp-20, tsp-25 and tsp-30 (nuclear). Growth of mutant cells at high temperature (35 degrees C) results in the rapid production of rho - cells and concomittantly in the decrease of the ability to transmit mitochondrial genetic information to the rho + progeny of crosses. Kinetics of rho - cell formation during growth at 35 degrees C have been compared with variations in transmission and recombination of mitochondrial markers in crosses. In all cases the transmission of mitochondrial markers of the ts-parent decreases as the number of cell generations increases. The frequencies of recombinants between mitochondrial markers either increase or decrease depending on the markers considered and the alleles of the omega-locus involved in the crosses. The results of all crosses performed have been compared with the predictions of the model for recombination and segregation of mitochondrial genes proposed by Dujon et al. (1974). This comparison indicates that the main result of high temperature treatment is a diminution of the input of mitochondrial information from the ts-parent into zygotes. Consequences of the induced variations of input follow the predictions of the model. The correlation found in ts-strains between the reduction of input in crosses and the formation of rho - cells is discussed in terms of molecular events occurring in mitDNA molecules during high temperature induction of rho + to rho - mutation.

Crosses, Genetic↗
PubMedDate not supplied

[Dependence of the duration of one mitotic cycle during synchronous cleavage divisions (tau o) on the temperature in 4 Rana species and the limits of the optimal temperatures for their reproduction and early development].

The dependence of the duration of one mitotic cycle during synchronous cleavage divisions (tau o) on temperature was studied in Rana temporaria, R. arvalis, R. lessonae, R. ridibunda and the corresponding curves were plotted in both linear and semilogarithmic scale. The curves can be used to characterize the relative duration of development, as well as to estimate the limits of optimal temperatures and to reveal the temperature-temporal regularities of development in these species.

Animals↗
PubMed1981

[The fluidity of alloys in high temperature. (Part 1) Testing apparatus of fluidity in high temperature (author's transl)].

The method and apparatus for testing the fluidity of molten alloy in the mold of high temperature as far as about 650 degrees C were designed and the fluidity of pure Ag and Ag-Cu alloy were measured. The results were summarized as follows. (1) The flow length (y mm) of pure Ag increased as the degree of superheat (B degree C) watch with casting temperature minus melting point and the temperature of mold (A degree C) increased. Estimating the formula for the flow length y, it was found that y was represented by the sum of the first order formula of A and B. (2) The flow length of Ag-Cu alloy took large value when the mold with heated up to 650 degrees C. Estimating the formula for the flow length y, it was found that y was represented by the sum of the third order formula of A and the first order formula of B and the formula of the product of A and B.

Copper↗
PubMed1994

Identification of temperature-sensitive mutants of the human immunodeficiency virus type 1 protease through saturation mutagenesis. Amino acid side chain requirements for temperature sensitivity.

Human immunodeficiency virus type 1 encodes a protease whose activity is required for the production of infectious virus. An Escherichia coli expression and processing assay system was used to screen 285 protease mutants for temperature-sensitive activity. Fourteen protease mutants had a temperature-sensitive phenotype, and approximately half resulted from conservative amino acid substitutions. Of the 14 substitutions that conferred a temperature-sensitive phenotype, 11 substitutions occurred at 6 positions that represent 3 pairs of residues in the protease that contact each other in the three-dimensional structure. These mutants assist in pinpointing regions of the protease that are important for enzyme activity and stability.

Amino Acids↗
PubMed1994

[Principles of temperature regulation changes in man in overheating and integral criteria for evaluation of his temperature status].

The new integral criteria for evaluation of heat conditions are based on the principles of temperature changes in overheating: from the comfortable state to the extreme overheating. The principles are revealed by manifold analyzing the correlations between dynamic rows of the temperatures measured in various body sites. The suggested criteria give more complete information in comparison with the regular parameters.

Adult↗
PubMed1976

[Relationship between temperatures behavior following short-term exposure of fingers to heat and cold and various anthropometric index values. Contribution on the problem of temperature regulation in man].

On a sample of n=201 male students between 18 and 30 years cold resp. heat tolerance tests were carried out in order to examine, how far correlations to anthropometric traits are present. No correlation between body height and heat resp. cold tolerance were found. Against that body weight, ROHRER-Index, subcutaneous fat tissue, weight/surface-ratio and surface/weight-ratio showed marked correlations with variations in body temperature. Particularly in the cold tolerance test more heavy and fatty individuals were characterist by a greater ability to store body heat as the decrease of temperature in them was obviously lower. The anthropological significance of these observations is discussed.

Adolescent↗
PubMed1995

Higher environmental temperature-induced increase of body temperature: involvement of central opioidergic-GABAergic interaction.

Exposure (2 h) of male albino rats to higher environmental temperature (HET, 40 degrees C) significantly increased the body temperature (BT). Administration of bicuculline (1 mg/kg, i.p.), physostigmine (0.2 mg/kg, i.p.), or their combination significantly raised the BT of normal rats (kept at 28 degrees C) or of HET-exposed rats. Atropine (5 mg/kg, i.p.) abolished the hyperthermic effect of bicuculline in normal and HET-exposed rats. The BT of normal and HET-exposed rat was increased with morphine (1 mg/kg, i.p.) and was reduced with naloxone (1 mg/kg, i.p.). Bicuculline or physostigmine-induced rise in BT of HET-exposed rats was potentiated following cotreatment of physostigmine with morphine. Atropine-induced hypothermia was abolished due to the cotreatment of atropine with morphine with physostigmine but was attenuated with atropine. In normal rats (kept at 28 degrees C), only atropine attenuated (morphine + bicuculline)-induced hyperthermia. L-Dopa + carbidopa or haloperidol did not significantly affect the BT of rats under similar conditions. These results suggest that short-term (2 h) exposure to HET activates the opioidergic neuron, which activates cholinergic activity through the inhibition of GABAergic system and, thus, enhances the BT.

Animals↗
PubMed1999

Thermal energy balance and body temperature: comparison between isolated ultrafiltration and haemodialysis at different dialysate temperatures.

BACKGROUND: Haemodynamic stability is better maintained during isolated ultrafiltration (i-UF) than during combined ultrafiltration/haemodialysis (UF + HD). This difference might be explained by differences in thermal energy balances. In this study we compared the thermal energy balance of i-UF with UF + HD at different dialysate temperatures (Td) and determined the Td at which the thermal energy balance during UF + HD is similar to the thermal energy balance during i-UF. METHODS: In the first part of the study, 10 chronic haemodialysis patients were compared during three different treatment sessions, i-UF, UF + HD at Td of 35.5 degrees C and UF + HD at Td of 37.5 degrees C. The second part of the study consisted of one session of 1 h of UF + HD (UF + HD ET-set) with a pre-set energy transfer (ET) at the same level of ET found for that particular patient during i-UF in the first part of the study. RESULTS: First part of the study: body temperature (BT) decreased significantly during i-UF (-0.25 +/- 0.25 degrees C, P<0.05) and UF + HD 35.5 degrees C (-0.24 +/- 0.18 degrees C, P<0.05) and increased significantly during UF + HD 37.5 degrees C (+0.18 +/- 0.19 degrees C, P<0.05). The differences between the change in BT during UF + HD 37.5 degrees C compared with the other treatments were significant (P<0.05). ET gave a significantly more negative value during i-UF (-30.8 +/- 3.1 W, P<0.05) than during UF + HD 35.5 degrees C (-23.6 +/- 4.1 W, P<0.05). A slightly positive ET was found during UF + HD 37.5 degrees C (+0.4 +/- 4.7 W, P=not significant). Second part of the study: there was a slight, but not significant, decrease in BT during UF + HD ET-set (-0.17 +/- 0.26 degrees C). The changes in BT did not differ significantly between i-UF and UF + HD ET-set. After 1 h of UF + HD ET-set, the mean Td was 34.75 degrees C (34.0-36.0 degrees C). The correlation between pre-dialysis BT and Td during UF + HD ET-set was significant (r=0.764, P<0.05). CONCLUSION: ET gives a more negative value during i-UF than during UF + HD 35.5 degrees C and than during UF + HD 37.5 degrees C. To obtain the same thermal ET during UF + HD as that achieved during i-UF, a mean Td of 34.75 degrees C is needed, depending on the pre-dialytic BT of the patient. The results of this study may be of relevance in relation to future clinical investigations which can elucidate whether differences in vascular response between i-UF and UF + HD are only related to differences in thermal balance.

Aged↗
PubMed2001

Ambient temperature modulates hypoxic-induced changes in rat body temperature and activity differentially.

When rats, acclimated to an ambient temperature (T(a)) of 29 degrees C, are exposed to 10% O(2) for 63 h, the circadian rhythms of body temperature (T(b)) and level of activity (L(a)) are abolished, T(b) falls to a hypothermic nadir followed by a climb to a hyperthermic peak, L(a) remains depressed (Bishop B, Silva G, Krasney J, Salloum A, Roberts A, Nakano H, Shucard D, Rifkin D, and Farkas G. Am J Physiol Regulatory Integrative Comp Physiol 279: R1378-R1389, 2000), and overt brain pathology is detected (Krasney JA, Farkas G, Shucard DW, Salloum AC, Silva G, Roberts A, Rifkin D, Bishop B, and Rubio A. Soc Neurosci Abstr 25: 581, 1999). To determine the role of T(a) in these hypoxic-induced responses, T(b) and L(a) data were detected by telemetry every 15 min for 48 h on air, followed by 63 h on 10% O(2) from rats acclimated to 25 or 21 degrees C. Magnitudes and rates of decline in T(b) after onset of hypoxia were inversely proportional to T(a), whereas magnitudes and rates of T(b) climb after the hypothermic nadir were directly proportional to T(a). No hyperthermia, so prominent at 29 degrees C, occurred at 25 or 21 degrees C. The hypoxic depression of L(a) was least at 21 degrees C and persisted throughout the hypoxia. In contrast, T(a) was a strong determinant of the magnitudes and time courses of the initial fall and subsequent rise in T(b). We propose that the absence of hyperthermia at 21 and 25 degrees C as well as a persisting hypothermia may protect the brain from overt pathology.

Abdomen↗
PubMed1977

Comparison of physical characteristics, body temperature and basal metabolism between Thai and Japanese in a neutral temperature zone.

The aim of this research is to compare the physical status, basal metabolism and some other physiological characteristics between native Thai in Bangkok, Thailand, and native Japanese in Japan, and discuss the results regarding acclimatization to tropical climate. Measurements of the Thai were made in September in Bangkok, while those of native Japanese were done in August at Nishinomiya (Japan). The subjects were adult males (20-22 years old) in both cases. Physically the Thai are generally a little shorter and more slender than Japanese in the mean value. The mean skinfold thickness for Thai was 8.4 mm, which is significantly less than that of Japanese (11.0 mm). The mean oral temperature measured under basal conditions was the same between both subject groups. The Thai showed a slightly lower basal metabolism per unit body surface, and mean skin temperature measured in a similar environmental condition was lower for Thai than for Japanese. The results of anthropometric measurements and physiological characteristics measured were discussed in view of physiology of acclimatization ot tropical climate.

Acclimatization↗
PubMed1995

Human papillomavirus 11 E5a delays the growth restriction induced by temperature shift in temperature-sensitive simian virus 40 T antigen-immortalized keratinocytes.

The transfection with human papillomavirus type 11 E5a oncoprotein can cause longer and more active proliferation in the human keratinocytes previously transfected stably with temperature sensitive SV40 T antigen at 39 degrees C. Also, after the E5a transfection in parental temperature sensitive SV40 T antigen gene transfected cells, we observe a delay in the accumulation of p21 gene at 39 degrees C. Moreover, T antigen degradation did not occur at 39 degrees C in the E5a transfected cells as it did in the parental cells. We draw from these observations that E5a may transiently stabilize temperature sensitive T antigen and/or repress p21 synthesis.

Antigens, Polyomavirus Transforming↗
PubMed2002

Alkanediyl-alpha,omega-bis(dimethylalkylammonium bromide) surfactants: II. Krafft temperature and melting temperature.

The melting temperature T(M) of two series of dimeric (gemini) surfactants, the alkanediyl-alpha,omega-bis(dodecyl and hexadecyl dimethylammonium bromide), referred to as 12-s-12 and 16-s-16, respectively (s = carbon number of the alkanediyl spacer), and the Krafft temperature T(K) of 1 wt% aqueous solutions of these surfactants have been measured. The melting temperature of the solid surfactant increases with the carbon number m of the alkyl chain. For each surfactant series, T(M) goes through a maximum at s close to 5, irrespective of the value of m. For the 12-s-12 series, T(M) goes through a minimum at s = 10 to 12. At a constant value of s, the value of T(K) increases with m. The variations of T(M) and T(K) with s show some correlation, with T(K) decreasing when T(M) increases and vice versa. The results are discussed in relation to the solution properties of the investigated surfactants.

Journal Article↗
PubMed2002

Study by scanning tunneling microscopy of hydrogen adsorption and desorption on Si111 7 x 7 at room temperature and at high temperature.

An overview is given on the use of scanning tunneling microscopy (STM) for investigation of the adsorption of hydrogen on Si(111)7 x 7 both at room temperature and at elevated temperature to finally obtain a hydrogen-saturated surface of Si(111). The initial stages are characterized by high reactivity of Si adatoms of the 7 x 7 structure. After adsorption of hydrogen on the more reactive sites in the beginning of the adsorption experiments a regular pattern, which is different for room and elevated temperature, is observed for the less reactive sites. In agreement with previous work, local 1 x 1 periodicity of the rest atom layer and the presence of di- and trihydride clusters is observed for hydrogen-saturated surface. STM has also been used to characterize surfaces from which the hydrogen atoms have been removed by thermal desorption. Finally, tip-induced desorption by large positive sample-bias voltages and by increasing the tunneling current will be described.

Journal Article↗
PubMed2006

Determination of sample temperature and temperature stability with 129Xe NMR.

The (129)Xe chemical shift of xenon dissolved in isotropic liquids is very sensitive to solvent density, which in turn is dependent on the sample temperature. Therefore, the (129)Xe chemical shift can be used as the basis of a thermometer for measuring actual sample temperatures in NMR experiments. Good accuracy can be achieved, but the thermometer is particularly useful in monitoring temperature stability. In the present case, carbon tetrachloride (CCl(4)), ethylbromide (C(2)H(5)Br), and deuterated chloroform (CDCl(3)) were chosen as solvents because of their large thermal expansion coefficient.

Journal Article↗
PubMed2005

Temperature dependence and kinetic isotope effects for the OH + HBr reaction and H/D isotopic variants at low temperatures (53-135 K) measured using a pulsed supersonic Laval nozzle flow reactor.

The reactions of OH + HBr and all isotopic variants have been measured in a pulsed supersonic Laval nozzle flow reactor between 53 and 135 K, using a pulsed DC discharge to create the radical species and laser induced fluorescence on the A 2sigma <-- X 2pi (v' = 1 <-- v'' = 0) transition. All reactions are found to possess an inverse temperature dependence, in accord with previous work, and are fit to the form k = A(T/298)(-n), with k1 (OH + HBr) = (10.84 +/- 0.31) x 10(-12) (T/298)(-0.67+/-0.02) cm3/s, k2 (OD + HBr) = (6.43 +/- 2.60) x 10(-12) (T/298)(-1.19+/-0.26) cm3/s, k3 (OH + DBr) = (5.89 +/- 1.93) x 10(-12) (T/298)(-0.76+/-0.22) cm3/s, and k4 (OD + DBr) = (4.71 +/- 1.56) x 10(-12) (T/298)(-1.09+/-0.21) cm3/s. A global fit of k vs T over the temperature range 23-360 K, including the new OH + HBr data, yields kT = (1.06 +/- 0.02) x 10(-11) (T/298)(-0.90+/-0.11) cm3/s, and (0.96 +/- 0.02) x 10(-11) (T/298)(-0.90+/-0.03) exp((-2.88+/-1.82 K)/T) cm3/s, in accord with previous fits. In addition, the primary and secondary kinetic isotope effects are found to be independent of temperature within experimental error over the range investigated and take on the value of (kH/kD)(AVG) = 1.64 for the primary effect and (kH/kD)(AVG) = 0.87 for the secondary effect. These results are discussed within the context of current experimental and theoretical work.

Journal Article↗
PubMed2004

Temperature-dependent micellar structures in poly(styrene-b-isoprene) diblock copolymer solutions near the critical micelle temperature.

The temperature dependence of the micelle structures formed by poly(styrene-b-isoprene) (SI) diblock copolymers in the selective solvents diethyl phthalate (DEP) and tetradecane (C14), which are selective for the PS and PI blocks, respectively, have been investigated by small angle neutron scattering (SANS). Two nearly symmetric SI diblock copolymers, one with a perdeuterated PS block and the other with a perdeuterated PI block, were examined in both DEP and C14. The SANS scattering length density of the solvent was matched closely to either the core or the corona block. The resulting core and corona contrast data were fitted with a detailed model developed by Pedersen and co-workers. The fits provide quantitative information on micellar characteristics such as aggregation number, core size, overall size, solvent fraction in the core, and corona thickness. As temperature increases, the solvent selectivity decreases, leading to substantial solvent swelling of the core and a decrease in the aggregation number and core size. Both core and corona chains are able to relax their conformations near the critical micelle temperature due to a decrease in the interfacial tension, even though the corona chains are always under good solvent conditions.

Journal Article↗
PubMed1997

Filamentary microstructure and linear temperature dependence of normal state transport in optimized high temperature superconductors.

A filamentary model of "metallic" conduction in layered high temperature superconductive cuprates explains the concurrence of normal state resistivities (Hall mobilities) linear in T (T-2) with optimized superconductivity. The model predicts the lowest temperature T0 for which linearity holds and it also predicts the maximum superconductive transition temperature Tc. The theory abandons the effective medium approximation that includes Fermi liquid as well as all other nonpercolative models in favor of countable smart basis states.

Journal Article↗