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At least 649 records · Page 36Linked to original sources
PubMed2003

Effect of freeze-dried immobilized cells on delignified cellulosic material in low-temperature and ambient-temperature wine making.

In this article, we report on wine making by freeze-dried immobilized cells on delignified cellulosic material for ambient and low temperatures. Biocatalyst supported by freeze-dried delignified cellulosic (FDC) material recovered after the first repeated-batch fermentations the fermentation efficiency and startup, which become about equal to those of biocatalyst supported by wet delignified cellulosic material. The FDC biocatalyst was suitable for wine making at low temperatures (5-15 degrees C), and produced wine of 12% alcoholic degree, with the main volatiles contained in the wine and reduced by a decrease in temperature. The fermentation efficiency was not affected by total acidity of must, while an increase in initial Be density improved percentages of higher alcohols and ethyl acetate. The quality of the wine was validated by a preliminary taste test to be in the range of acceptable to excellent.

Catalysis↗
PubMed1976

The storage of cow eggs at room temperature and at low temperatures.

The survival and development of cow eggs in the rabbit oviduct after storage at room temperature and after cooling and storage at 0-7-5 degrees C was examined. In PBS medium at room temperature 88% of Day-5 and 85% of Day-3 eggs showed normal development, but in TCM 199, 71% of Day-5 and only 49% of Day-3 eggs showed normal development. Duration of storage (1 1/2-2 hr or 6 1/2-7 1/2 hr) and cleavage stage before storage had no appreciable effect on development. Some retardation of development occurred in Day-3 eggs after 96 hr in the rabbit oviduct when compared to Day-5 eggs after 48 hr. Cooling of Day-5 and Day-6 eggs to 0-7-5 degrees C resulted in degeneration of a large proportion of eggs. Of the factors examined, storage medium (PBS or PBS+20%FCS), storage time (2 min, 24 hr) and storage temperature (0, 2, 5 or 7-5 degrees C) had little effect, but slower cooling rates tended to improve survival of eggs although the differences were not significant. More morulae (greater than 32 cells) than 8-to 24-celled eggs developed normally.

Animals↗
PubMed1979

Body temperature and oxygen consumption of newborn rats at various ambient temperatures.

The thermogenic response and rectal temperature (Tre) of newborn rats (0 to 32 days old) on exposure to various ambient temperatures (Ta) were investigated. The O2 consumption (VO2 in ml . min-1 per 100 cm2 surface area) was measured for one rat at a time by means of a closed circuit system. The results were that (1) within the thermal neutral ranges, Tre stood at 36--37 degrees C regardless of the age and the value of VO2 was lowest at the age of 6--7 days, after this period increasing and reaching a level of 1.4 ml . min-1 . cm-2 X 10(-2) after 18--21 days old (the weaning period); (2) the thermogenic response to cold (delta VO2/--delta Ta) was higher at ages prior to the weaning period than after the weaning period; (3) in spite of the higher thermogenic responses, Tre decreased markedly on exposure to cold prior to the weaning period, because of a poor development of thermal insulation; and (4) the achievement of homeothermy of the rat at subneutral temperatures was observed after the weaning period.

Animals↗
PubMed1981

Finite element temperature analysis of a total hip replacement and measurement of PMMA curing temperatures.

Analytical and experimental studies were performed to examine some characteristics of poly(methyl methacrylate) bone cement in the context of total hip replacement. Proceeding from fundamental principles of balance of energy and heat conduction, three simulation models of total hip replacement, using the finite-element method of numerical analysis, were used to predict the temperature response in the femoral prosthesis, cement, cancellous bone, and bone-cement interface. When cement collars are a centimeter or less in thickness, the models predict little likelihood of permanent bone thermal necrosis. In addition, laboratory experimental results indicate that peak temperatures attained in Simplex-P and Palacos-R cement specimens are nearly identical and that adding 0.5 and 1.0 g of the antibiotic gentamicin to Palacos-R has negligible influence on peak temperature. Experimental results also indicate that cooling cement specimens to 8 degrees C extends the set time, which in turn could significantly increase the likelihood of stem-cement loosening during surgery.

Bone Cements↗
PubMed1979

The temperature and pH-dependent transition of hen lysozyme. Characterization of two temperature-defined domains and of an N-acetylglucosamine (inhibitor)-insensitive form.

The previously described temperature and pH-dependent transition in the solid state of hen lysozyme was studied in solution. Experiment concerning the velocity of lysis of M. luteus by lysozyme and its behavior in presence of an inhibitor (GlcNAc) as well as a reinvestigation of the Arrhenius curves over a large range of pH, demonstrated the existence of two temperature-induced domains. An inhibitor-insensitive lysozyme form was characterized at 40 degrees (physiological temperature).

Acetylglucosamine↗
PubMed1977

Adaptation of biological membranes to temperature. The effect of temperature acclimation of goldfish upon the viscosity of synaptosomal membranes.

The fluidity of synaptosomal membrane preparations isolated from goldfish acclimated to 5, 15 and 25 degrees C and from rat has been estimated using the fluorescence polarisation technique with 1,6-diphenyl-1,3,5-hexatriene as probe. Membranes of cold-acclimated goldfish were more fluid than those of warm-acclimated goldfish when measured at an intermediate temperature, indicating a temperature-dependent regulation of this parameter. Similarly, membranes of warm-acclimated goldfish were more fluid than those prepared from rat brain. Liposomes prepared from the purified phospholipids of goldfish and rat synaptosomal preparations showed differences similar to those of the native membranes. Increased membrane fluidity of cold-acclimated goldfish was correlated with a decrease in the proportion of saturated fatty acids of the major phospholipid classes and an increased unsaturation index in choline phosphoglycerides. Rat membranes showed a substantial reduction in unsaturation index and an increase in the proportion of saturated fatty acids compared to the membranes of 25 degrees C-acclimated goldfish. The cholesterol content of synaptosomal membranes of goldfish was unaffected by acclimation treatment. The role of homeoviscous adaptation in the compensation of the rates of membrane processes during thermal acclimation, and upon the resistance adaptation of poikilotherms to extreme temperatures is discussed.

Acclimatization↗
PubMed1989

Isolation of mutants showing temperature-sensitive cell growth from embryonal carcinoma cells: control of stem cell differentiation by incubation temperatures.

Embryonal carcinoma(EC) cells, the undifferentiated stem cells of teratocarcinomas, have many properties in common with pluripotent embryonic cells, and thus provide an excellent system for studying the early events involved in embryonic development and stem cell differentiation. We have isolated three novel mutants with temperature-sensitive(ts) cell growth that were able to differentiate at a non-permissive temperature for cell growth. These mutations affect the progression of the cell cycle, leading to the transient accumulation of cells in a specific phase, the S phase, of the cell cycle, which is likely to be the primary cause of stem cell differentiation of EC cells at non-permissive temperature. Isolation of these mutants strongly supports the notion that there is a close association between the inhibition of DNA synthesis and EC cell differentiation.

Animals↗
PubMed1976

A membrane model describing the effect of temperature on the water conductivity of erythrocyte membranes at subzero temperatures.

Thermodynamic models show that the loss of intracellular water from human erythrocytes during freezing depends heavily upon the water conductivity of the erythrocyte membrane. These calculations, which are based on the simple extrapolation of ambient conductivity data to subzero temperatures, show that more than 95% of cell water is transferable during freezing, whereas experiments show that at least 20% of cell water is retained. A study of the effects of different published values for the membrane water conductivity on cell water retained during freezing shows that this discrepancy may be a consequence of the simple extrapolation procedure. For a homogeneous membrane system, absolute reaction rate theory was used to develop a surface-limited permeation model that includes the resistance to the flow of water not only through the interior region of the membrane but also across possible rate-limiting barriers at the solution-membrane interfaces. The model shows that it is unlikely that a single rate-limiting process dominates water transport in the red cell as it is being cooled from ambient to subzero temperatures. The effective membrane conductivity at subzero temperatures could possible be much lower than a simple extrapolation of existing data would predict. With the aid of this model analytical predictions of intracellular water during freezing are more consistent with experimental observations.

Blood↗
PubMed1982

Separation of temperature sensitive and temperature insensitive components of the postsynaptic potentials in the frog motoneurons.

Intracellular measurements were made in the in situ spinal cord of the frog at temperatures below 5 degrees C. Responses to volleys in the sciatic nerve, in the descending fibres and in the motor axons were studied. About 30% of the motoneurons responded to sciatic volleys with 1-3 ms segmental latency, which was short enough to assume electrotonic mediation of these responses. Another group of motoneurons responded with 6-8 ms latency, i.e. with the expected delay at chemical synapses at low temperature. Latency distribution of the sciatic-evoked postsynaptic potentials was clearly bimodal in contrast with that found at higher temperatures. Postsynaptic discharges occurred with rather long latency and they were attributed to chemically-mediated excitation. Some of the postsynaptic potentials to descending volleys also occurred with quite short latency, indicating possible electrotonic transmission from supraspinal centres to motoneurons. Latency distribution of the action potentials evoked from the motor axons was bimodal, corresponding to the different, i.e. antidromic and recurrent facilitatory, mechanism of these spikes. Calculated Q10 ratios for the sciatic-evoked reflex discharges and the afferent fibre volleys were about 2.3 and 1.8, respectively. We concluded that cooling helps to separate postsynaptic potentials according to their electrotonic and chemical mediation and that electrotonic excitation does not seem to have a primary role in the generation of postsynaptic discharges initiated by dorsal root volleys in the frog.

Afferent Pathways↗
PubMed2001

Measurements and predictions of growth for Listeria monocytogenes and Salmonella during fluctuating temperature II. Rapidly changing temperatures.

Growth of Listeria monocytogenes and Salmonella was examined during various rates of increase and decrease in temperature from and to the minimum for growth. Growth was little affected by even the most rapid changes and injury or lag was not observed. Subsequent investigations of growth during periods of rapid variation in temperature from and to temperatures below the growth minimum again had little effect and growth was satisfactorily predicted using the dynamic model of Baranyi and Roberts [Int. J. Food Microbiol. 23 (1994) 277] in conjunction with the data of Food Micromodel.

Colony Count, Microbial↗
PubMedDate not supplied

An influenza A live attenuated reassortant virus possessing three temperature-sensitive mutations in the PB2 polymerase gene rapidly loses temperature sensitivity following replication in hamsters.

The purpose of the present study was to produce an influenza A H2N2 donor virus from which an attenuating PB2 gene bearing three discrete temperature sensitive (ts) mutations could be readily transferred to currently epidemic influenza A H1N1 and H3N2 viruses via genetic reassortment. An influenza A transfectant virus was first produced that contained site-directed ts mutations at amino acids 112, 265, and 556 in the PB2 gene of influenza A/AA/60 virus origin in a background of the other seven RNA segments from the influenza A/LA/87 (H3N2) virus. The A/LA/87 PB2 ts transfectant virus (clone 22B1) was mated with the A/AA/60 (H2N2) wild type virus, and six H2N2 ts reassortants were obtained. One reassortant virus, clone 25A1, possessed the triple ts PB2 gene in the context of all seven other genes of homologous A/AA/60 origin. Isolation of this reassortant permitted an examination of the contribution of the ts mutations present in a triple ts PB2 transfectant virus to its attenuation and phenotypic stability independent from an effect of the A/AA/60-A/LA/87 gene constellation on attenuation. It was found that the A/AA/60 triple ts reassortant virus was less ts, less attenuated, and less phenotypically stable than the A/LA/87 triple ts transfectant virus from which it was derived. The A/AA/60 reassortant possessing the PB2 gene containing three introduced ts mutations underwent rapid and significant loss of its temperature sensitivity following replication in the lungs of immunocompetent hamsters. This indicated that the A/AA/60-A/LA/87 gene constellation contributed significantly to the overall level of temperature-sensitivity, attenuation, and stability of the A/LA/87 triple ts transfectant virus. It is likely that the instability of the ts phenotype exhibited by the A/AA/60 triple ts reassortant virus would not be acceptable for a vaccine to be used in humans. The implications of these findings for the usefulness of ts mutations as the sole attenuating mutation in influenza virus vaccines is discussed.

Animals↗
PubMed2003

Pediatric temperature measurement and child/parent/nurse preference using three temperature measurement instruments.

This study compared the tympanic thermometer with the electronic and chemical dot thermometers used at the axillary site and evaluated child, parent, and nurse preferences for method of temperature measurement. The child's (n = 146) temperature was measured using each of the three methods. Each child, parent, and nurse was asked to select a preference for device and site. Results were analyzed using the Bland-Altman method. Results showed that most of the paired readings fell within the Bland-Altman limits of agreement (LOA). When the chemical dot and tympanic temperature readings were compared with the electronic axillary reading, the tympanic thermometer was found to be in closer agreement. The chemical dot thermometer placed in the axilla consistently read higher than the electronic thermometer in the same site. Children, parents, and nurses preferred the tympanic thermometer.

Body Temperature↗
PubMed2006

Temperature- and length-dependent energetics of formation for polyalanine helices in water: assignment of w(Ala)(n,T) and temperature-dependent CD ellipticity standards.

Length-dependent helical propensities w(Ala)(n,T) at T = 10, 25, and 60 degrees C are assigned from t/c values and NMR 13C chemical shifts for series 1 peptides TrpLys(m)Inp2(t)Leu-Ala(n)(t)LeuInp2Lys(m)NH2, n = 15, 19, and 25, m = 5, in water. Van't Hoff analysis of w(Ala)(n,T) show that alpha-helix formation is primarily enthalpy-driven. For series 2 peptides Ac-Trp Lys5Inp2(t)Leu-(beta)AspHel-Ala(n)-beta-(t)LeuInp2Lys5NH2, n = 12 and 22, which contain exceptionally helical Ala(n) cores, protection factor-derived fractional helicities FH are assigned in the range 10-30 degrees C in water and used to calibrate temperature-dependent CD ellipticities [theta](lambda,H,n,T). These are applied to CD data for series 1 peptides, 12 < or = n < or = 45, to confirm the w(Ala)(n,T) assignments at T = 25 and 60 degrees C. The [theta](lambda,H,n,T) are temperature dependent within the wavelength region, 222 +/- 12 nm, and yield a temperature correction for calculation of FH from experimental values of [theta](222,n,T,Exp).

Circular Dichroism↗
PubMed1967

Influence of temperature acclimatization on the temperature-dependence and ouabain-sensitizing of goldfish intestinal adenosine triphosphatase.

1. Homogenates of goldfish intestinal mucosa were separated into various fractions by differential centrifugation. Both adenosine-triphosphatase and beta-glycerophosphatase activities were found to be concentrated mainly in a membrane fraction which sedimented after 1200000g-min. 2. This membrane adenosine-triphosphatase system was activated by Na(+)+K(+) and inhibited by ouabain. 3. The ouabain-sensitive adenosine-triphosphatase activity was high and the ouabain-insensitive activity low in membrane fractions prepared from fish acclimatized previously to 8 degrees . The opposite was true for fish acclimatized to 30 degrees . 4. The Arrhenius plots of ouabain-sensitive and ouabain-insensitive adenosine-triphosphatase activities, measured from 5 degrees to 30 degrees , showed discontinuities at incubation temperatures that varied with the previous acclimatization temperature of the fish. 5. It is considered that modification of the membrane adenosine-triphosphatase system in goldfish intestinal mucosa may serve to regulate Na(+) transport at different environmental temperatures.

Acclimatization↗
PubMed1970

Temperature-sensitive mutants of Bacillus subtilis. I. Multiforked replication and sequential transfer of DNA by a temperature-sensitive mutant.

A temperature-sensitive mutant of Bacillus subtilis 168 was isolated. Its chromosome was found to undergo multiforked replication at normal temperature. The mutant cells then transferred chromosomes to recipient cells sequentially from the origin to the terminus of the chromosome at sublethal temperatures. Sequential transfer of the chromosome facilitated the determination of the relative positions of markers on the chromosome. Linkage between origin (adenine-16) and terminus (methionine) was demonstrated.

Adenine↗
PubMed1996

Temperature change in cryo-containers during short exposure to ambient temperatures.

Times have been defined for the handling of 0.25 ml embryo cryostraws and semen, in either 0.5 ml cryostraws or 1.0 ml cryovials containing 0.5 ml material, before potentially detrimental changes in temperature take place. When handling cryovials the time lag is relatively long, with 78.8 +/- 2.6 s being available to manipulate the vials before -80 degrees C is reached and 335.4 +/- 3. 8 s until the eutectic point (approximately -7 degrees C) is reached. However the situation with cryostraws is less tolerant. Both 0.25 and 0.5 ml versions reach temperatures >-80 degrees C within 40 s, and the eutectic point is reached in 79.0 +/- 2.0 s in 0.25 ml cryostraws. These time/temperature data have proved useful in educating new technicians, as well as clinicians and nurses who may also handle frozen human material, in the need to minimize the ambient temperature exposure time of stored specimens so as to maintain optimal post-thaw viability.

Cryopreservation↗
PubMed2002

Influence of the irradiation temperature on the dosimetric and high temperature TL peaks of Al2O3:C.

The TL glow curves of Al2O3:C crystals have been investigated as a function of the irradiation temperature. The nature of the observed TL peaks has been studied by optical annealing. The filling of traps was found strongly dependent on the irradiation temperature in the case of UV exposure, which has been explained by the temperature dependence of the photoionisation of F centres. This latter phenomenon could have a part in the luminescence quenching and UV bleaching of F centres.

Aluminum Oxide↗
PubMed1999

Amino acid changes in the repressor of bacteriophage lambda due to temperature-sensitive mutations in its cI gene and the structure of a highly temperature-sensitive mutant repressor.

The mutant cIts genes from seven different lambdacIts phages carrying tsU50, tsU9, tsU46, ts1, tsU51, tsI-22 and ts2 mutations were cloned in plasmid. The positions of these mutations and the resulting changes of amino acids in the repressor were determined by DNA sequencing. The first four mutations mapping in the N-terminal domain show the following changes: I21S, G53S, A62T and V73A, respectively. Of the three remaining mutations mapping in the C-terminal domain, cItsI-22 and cIts2 show N207T and K224E substitutions respectively, while the mutant cItsU51 gene carries F141I and P153L substitutions. Among these ts repressors, CIts2 having the charge-reversal change K224E was overexpressed from tac promoter in a plasmid and purified, and its structure and function were studied. Operator-binding studies suggest that the ts2 repressor is somewhat defective in monomer-dimer equilibrium and/or cooperativity even at permissive temperatures and loses its operator-binding ability very rapidly above 25 degrees C. Comparative studies of fluorescence and CD spectra, sulfhydryl group reactivity and elution behaviour in size-exclusion HPLC of both wild-type and ts2-mutant repressors at permissive and non-permissive temperatures suggest that the C-terminal domain of the ts2 repressor carrying a K224E substitution has a structure that does not favor tetramer formation at non-permissive temperatures.

Amino Acid Substitution↗