PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Cold Temperature”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1993

L1 adhesion molecule on mouse leukocytes: regulation and involvement in endothelial cell binding.

L1 is a cell surface glycoprotein of the immunoglobulin superfamily which was initially shown to mediate adhesion between neural cells. Recently we have reported that L1 is expressed by bone marrow cells and the majority of mature lymphocytes (Kowitz et al., Eur. J. Immunol. 1992. 22: 1199-1205). To analyze the function of L1 on leukocytes we studied its regulation following cell activation. In vitro activation of B lymphocytes with lipopolysaccharide or T lymphocytes with phorbol 12-myristate 13-acetate/Ca2+ ionophore, concanavalin A or anti-CD3 monoclonal antibody as well as in vivo activation of V beta 8+ T cells with staphylococcal enterotoxin B (SEB) revealed a down-regulation of L1 within 48 h. A rapid loss of L1 expression was seen when mouse neutrophils were activated with PMA alone. This rapid loss paralleled the shedding of L-selectin. We also studied a possible role of L1 in the binding of leukocytes to endothelial cells. ESb-MP lymphoma cells with a high expression of L1 (L1hi) could bind to bend3 endothelioma cells without prior activation with inflammatory cytokines. The interaction was inhibited by anti-L1 antibodies. In contrast, ESb-MP cells with low L1 expression (L1lo) were only marginally bound. Latex beads coated with affinity-isolated L1 antigen were also able to bind to the endothelioma cells in a specific fashion. The binding of ESb-MP lymphoma cells required Ca2+ and Mg2+ ions and was sensitive to cold temperature. Since the endothelioma cells did not express L1 the binding mechanism studied here is distinct from the established L1-L1 homotypic interaction. It is possible that the novel L1-mediated adhesion pathway involves an unidentified ligand and could play a role in leukocyte migration.

Animals↗
PubMed1980

Lymphocyte capping induced by polycationized ferritin.

In order to better understand the mechanism of lymphocyte surface receptor redistribution induced by externally added ligands, polycationized ferritin (PCF), a nonconventional ligand, was tested using both fluorescence and electron microscopy for its ability to cause patching and capping of anionic molecules on the surface of both transformed and normal mouse lymphocytes. Binding of PCF at 0 degree C for 1 hour induces the appearance of patches; subsequent incubation at 37 degrees for 30--60 minutes causes the formation of a cap structure with the lymphoid cells tested (T-lymphoma cells and splenic lymphocytes). Using various experimental treatments (e.g., sodium azide, cytochalasin B and D, colchicine, prefixation, and cold temperatures), PCF-induced capping has been found to be temperature sensitive, and to require metabolic energy and an intact cytoskeletal system. In addition, using double immunofluorescence techniques which involve rhodamine-labeled PCF and fluorescein-conjugated heavy meromyosin, it has been observed that the formation of the PCF-induced cap coincides with an accumulation of intracellular actin directly beneath the cap structure. Furthermore, agents such as dibutyryl cyclic AMP and theophylline, which cause an increase in intracellular cyclic AMP, have been shown to stimulate PCF-associated capping. This study suggests that increasing levels of intracellular cyclic AMP may activate, directly or indirectly, membrane-associated contractile elements required for the aggregation of membrane proteins into patches and caps.

Actins↗
PubMed2003

Choline acetyltransferase mutations in myasthenic syndrome due to deficient acetylcholine resynthesis.

The myasthenic syndrome due to abnormal acetylcholine resynthesis is characterized by early onset, recessive inheritance, and recurrent episodes of potentially fatal apnea. Mutations in the gene encoding choline acetyltransferase (CHAT) have been found to account for this condition. We have identified five patients from three independent families with features of this disease including, in four patients, a paradoxical worsening of symptoms with cold temperatures. Electrodiagnostic studies demonstrated impaired neuromuscular transmission in all patients. In vitro microelectrode studies performed in the anconeus muscle biopsies of two patients showed moderate reduction of quantal release. Electron microscopy of the neuromuscular junction was normal in both patients. Each patient had two heterozygous CHAT mutations including L210P and P211A (family 1), V194L and V506L (family 2), and R548stop and S694C (family 3). Three of these mutations have previously been reported and suggest that, in this syndrome, some molecular defects may be more prevalent than others.

Acetylcholine↗
PubMed1995

Effects of temperature on motor unit action potentials during isometric contraction.

The effect of temperature on motor unit action potential (MUAP) configuration and recruitment was studied using automatic decomposition electromyography (ADEMG) recordings from a concentric needle electrode placed in the first dorsal interosseous (FDI) muscle of 10 normal adult subjects during isometric contraction. Focally cooling the FDI resulted in prolonged MUAP duration (P < 0.001, ANOVA), a finding congruent with those of Buchthal. Focal ulnar cooling at the elbow resulted in the increased MUAP frequency. In contrast to previous studies, there were no significant differences in amplitude or turns. Greater understanding of normal motor unit electrophysiology is necessary to improve diagnostic accuracy of EMG testing.

Adult↗
PubMed1983

Effects of thermal applications on the abdominal temperature of dogs.

The results of thermal applications to the abdomens of unrestrained, unanesthetized dogs are reported. A silicone rubber envelope through which water circulated at 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, or 50 degrees C was applied. Skin surface, subcutaneous, intraperitoneal, intestinal, and colonic temperatures were measured after 90 minutes. Pad applications at 0 degrees, 10 degrees, 20 degrees, and 30 degrees C significantly lowered skin surface and subcutaneous temperatures, while pad applications at 40 degrees and 50 degrees C significantly increased subcutaneous and skin surface temperatures. None of the pad applications had a significant effect on intraperitoneal, intestinal, or colonic temperatures. The findings indicate that a wide range of thermal applications to the abdominal skin of the dog do not alter deep abdominal temperatures.

Abdomen↗
PubMed1993

Temporal variation in the effects of iced water on oral temperature.

The effect of iced water on the length of time required for oral temperature measurements to return to baseline in adults at 8:00 a.m. and 4:00 p.m. was examined. Each of the 24 subjects participated at both times of the day and thus served as his/her own control. Using electronic thermometers and standardized iced water solutions, the mean length of time required for oral temperature to return to baseline after ingestion of iced water was 14.04 min at 8:00 a.m. and 10.25 min at 4:00 p.m. This difference was statistically significant, supporting the hypothesized temporal variation in the effects of iced water on oral temperature measurement.

Adult↗
PubMed2001

Structural organization, regulation, and expression of the chloroplastic superoxide dismutase Sod1 gene in maize.

A cDNA and genomic clone encoding maize chloroplastic Cu/Zn superoxide dismutase Sod1 were isolated. Southern blot analysis indicated little homology between the chloroplastic (Sod1) and the cytosolic (Sod2, Sod4, Sod4A) cDNAs. Sequence analysis of the genomic clone revealed a promoter, transit peptide, and partial coding sequence. The promoter contained several response elements (e.g., for light, cold temperature, xenobiotics) that may be involved in the regulation of the Sod1 gene. Sod1 expression during development and in response to physiological and chemical stressors such as temperature, xenobiotics (paraquat), and light were examined.

Amino Acid Sequence↗
PubMed2000

Purification and characterization of protein kinase A from liver of the freeze-tolerant wood frog: role in glycogenolysis during freezing.

Freeze tolerance by various amphibians includes cryoprotectant production in the form of glucose. Activation of the catalytic subunit of liver cAMP-dependent protein kinase (PKAc) facilitates activation of glycogenolysis, a critical biochemical process necessary for production of glucose. Here, we purified PKAc from Rana sylvatica liver to determine the extent to which cold temperature, which stimulates cryoprotectant production, affected PKAc activity and function. PKAc was purified to greater than 95% homogeneity, with a final specific activity of 71 nmol phosphate transferred/min/mg protein. The molecular weight of frog liver PKAc was 47.6 +/- 1.1 kDa and K(m) values for the phosphate acceptor kemptide and Mg-ATP were 9.0 +/- 0.1 and 51.8 +/- 1.0 microM at 22 degrees C, respectively. K(m) values for both substrates dropped significantly at 5 degrees C. The enzyme was sensitive to specific inhibitors of mammalian PKAc (PKA(i), H89) but was only moderately inhibited by high salt concentrations. Furthermore, salt inhibition was reduced at low temperature. The effect of temperature on enzyme activity indicated a conformational change in PKAc at 10 +/- 2 degrees C, with calculated activation energies of 51 +/- 4 kJ/mol at temperatures above 10 degrees C and 110 +/- 9 kJ/mol below 10 degrees C. PKAc in wood frog liver plays a crucial role in mediating the freeze-induced glycogenolysis that is responsible for the production of 200-300 mM levels of glucose as a cryoprotectant. Differential effects of low temperature on enzyme function, increased substrate affinity and reduced ion inhibition, appear to be central to this role.

Acclimatization↗
PubMed1995

Cooling of peripheral myelinated axons retards Wallerian degeneration.

The histological and ultrastructural status of intact and severed axons was examined in the ventral tail nerve of rats whose tails were maintained at 32, 23, and 13 degrees C. Compared to contralateral intact nerves, distal (anucleate) portions of severed myelinated axons morphologically and ultrastructurally degenerated within 3 days at 32 degrees C and within 6 days at 23 degrees C. In contrast, anucleate myelinated axons in ventral tail nerves maintained at 13 degrees C did not degenerate for at least 10 days. These and other data suggest that rapid Wallerian degeneration of anucleate myelinated axons is not an inevitable result of axonal severance in mammals.

Animals↗
PubMed1993

Reproducibility of the finger cooling test.

A finger cooling test is used to objectify Raynaud's phenomenon and to assess its severity. For this purpose, finger skin temperature (FST) and laser Doppler flux (LDF) are measured on the fingertips before and during cooling of the hand (16 degrees water bath for 5 min) and a subsequent recovery period (20 min). To study reproducibility, this test was performed twice within 3 months in 34 healthy subjects and in 56 Raynaud patients. Three test parameters were used in the analysis: the baseline value, the value after 12 min of recovery, and the mean level during recovery. We determined the limits of agreement (mean differences between the first and the second test +/- 2SD) and the coefficients of variation. No systematic differences between the first and the second test were found. Outside temperature did not influence FST or LDF. FST was shown to have a better reproducibility than LDF. For the baseline value in the total group the coefficient of variation was 3.3% for FST and, rather high, 21.6% for LDF. The limits of agreement for the baseline value in the total group were -4.8 to 4.2 degrees for FST and -25.2 to 22.2 arbitrary units for LDF. In conclusion, the applied cooling test has limited value in individual cases, but can be useful when comparing large groups in pathophysiologic or therapeutic studies.

Adult↗
PubMed1996

Nickel (Ni2+) enhancement of alpha-tubulin acetylation in cultured 3T3 cells.

Stable microtubules (MTs) are well known to contain acetylated alpha-tubulin. Ni2+-induced MT bundling may be accompanied with such tubulin post-translational modification. To explore this possibility as a mechanism of Ni2+-induced cytoskeletal injury, we have examined acetylated alpha-tubulin levels in cultured 3T3 cells by both immunoprecipitation assays and fluorescent staining of MTs using a monoclonal antibody (clone 6-11B-1) specific for acetylated artubulin. Cell extracts prepared from [35S]methionine labeled cultures in the presence or absence of Ni2+ were immunoprecipitated and analyzed by SDS-PAGE followed by autoradiography. A predominant protein band (molecular mass 55 kDa), representing acetylated alpha-tubulin, appeared in Ni2+-treated cells in a dose and time-dependent manner whereas the corresponding labeled protein band was only barely detectable in control cells. Consistent with the immunoblot findings, MTs in control 3T3 cells in the absence of Ni2+ were not labeled by the 6-11B-1 antibody except for some short, discontinuous segments localized in the cell center or the perinuclear MT organizing center area. In contrast, treatment of cells with NiCl2 (2 mM for 20 hr) resulted in, as expected, the formation of MT bundles that were intensely stained by the 6-11B-1 monoclonal antibody specific for acetylated alpha-tubulin. Furthermore, MTs containing acetylated alpha-tubulin in Ni2+-treated cells were resistant to disassembly induced by nocodazole, and at least partially resistant to cold temperature (0 degrees C), which also depolymerizes MTs. Since acetylated alpha-tubulin serves as a marker for the presence of stable MTs, the marked enhancement of alpha-tubulin acetylation in Ni2+-treated cells indicates that stabilization of MTs may be an important mechanism by which Ni2+ induces cell injury since stabilized MTs in turn should favor MT bundling, an unusual form of cytoskeletal perturbation in response to Ni2+ exposure.

3T3 Cells↗
PubMed1992

Rewarming of feet by lower and upper body exercise.

The capacity of different types of exercise to rewarm the body, especially the feet, was studied. Six healthy male subjects wearing winter clothing (2.4 clo, 0.37 degrees C.m2.W-1) were exposed on three occasions to -15 degrees C for 120 min. For the first 60 min the subjects were cooled while sitting motionless and for the latter 60 min they were submitted to cycle ergometer exercise (CE), arm ergometer exercise (AE) or step exercise (ST). The rate of work in CE (about 350 W) served as a reference value for AE and ST. The cooling resulted in an average 1.7 (SEM 0.03) degrees C decrease in mean body temperature (Tb) corresponding to a 425 (SEM 9) kJ heat debt. The ST increased most effectively mean skin, rectal and lower body skin temperatures as well as dry heat loss. The ST increased Tb by 0.83 (SEM 0.16) degrees C, CE by 0.10 (SEM 0.11) degrees C and AE by only 0.07 (SEM 0.12) degrees C. At the end of the exercise the foot temperature was approximately 6 degrees C higher in ST than in CE. The superior rewarming by ST was apparently due to its low mechanical efficiency. Because the increase in Tb could not explain all the changes in foot temperatures, increased circulation and metabolism of the feet would also appear to have been involved.

Adult↗
PubMed1993

Does feeding regime affect physiologic and thermal responses during exposure to 8, 20, and 27 degrees C?

When the loss of body heat is accelerated by exposure to low environmental temperatures, additional substrates must be oxidized to provide energy to sustain temperature homeostasis. Therefore, the present investigation examined the relation between feeding regime [pre-experimental carbohydrate feeding (FED) vs a fast (FAST)], during 120 min of exposure to 8, 20, and 27 degrees C in well-nourished men. The following were examined: tissue insulation (I; degrees C.m2:W-1), rectal temperature (Tre; degrees C), and oxygen consumption (VO2; ml,kg-1.min-1). VO2, Tre, and I revealed no significant differences between treatments (FED vs FAST) at any temperature. At 27 degrees C, I was less (P < 0.05) than at 20 and 8 degrees C, and decreased (P < 0.05) as exposure time increased. At 8 degrees C, VO2 was higher (P < 0.5) than at 20 or 27 degrees C, and VO2 increased as time increased (P < 0.05). Tre decreased (P < 0.05) as time increased for all conditions. Respiratory exchange ration (R) differed (P < 0.05) between treatments (FED vs FAST), temperature (8 vs 20 degrees C), and across time. Values for R suggests that carbohydrate accounted for 56% and 33% of caloric utilization during the FED vs FAST conditions, respectively. At 8 vs 20 degrees C, R represented 54% vs 30% of carbohydrate utilization. Across time, R demonstrated that in both conditions (FED vs FAST) there was a decreased reliance on carbohydrate utilization for energy provision.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

Immunofluorescent and biochemical studies on tyrosine hydroxylase and dopamine-beta-hydroxylase of the bullfrog sciatic nerves.

Immunofluorescence specific for tyrosine hydroxylase (TH) or dopamine-beta-hydroxylase (DBH) was accentuated in both proximal and distal segments of the sciatic nerve after ligation. Estimations of the enzyme activities confirmed the above results. Mean axoplasmic flow rates of TH and DBH in bullfrog sciatic nerve were found to be 8 and 123 mm/day, respectively. They were decreased by colchicine or by cold temperatures (4 degrees C).

Animals↗