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At least 433 records · Page 24Linked to original sources
PubMed1999

Cold shock response of Bacillus subtilis: isoleucine-dependent switch in the fatty acid branching pattern for membrane adaptation to low temperatures.

Bacillus subtilis has developed sophisticated mechanisms to withstand fluctuations in temperature. Membrane fatty acids are the major determinants for a sufficiently fluid membrane state to ensure the membrane's function at all temperatures. The fatty acid profile of B. subtilis is characterized by a high content of branched fatty acids irrespective of the growth medium. Here, we report on the importance of isoleucine for B. subtilis to survive cold shock from 37 to 15 degrees C. Cold shock experiments with strain JH642 revealed a cold-protective function for all intermediates of anteiso-branched fatty acid biosynthesis. Metabolites related to iso-branched or straight-chain fatty acid biosynthesis were not protective. Fatty acid profiles of different B. subtilis wild-type strains proved the altered branching pattern by an increase in the anteiso-branched fatty acid content and a concomitant decrease of iso-branched species during cold shock. There were no significant changes in the fatty acid saturation or acyl chain length. The cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine correlated with their inability to synthesize more anteiso-branched fatty acids, as shown by the fatty acid profile. The switch to a fatty acid profile dominated by anteiso-C(15:0) and C(17:0) at low temperatures and the cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine focused our attention on the critical role of anteiso-branched fatty acids in the growth of B. subtilis in the cold.

Adaptation, Physiological↗
PubMed2005

Analysis of tracheal secretions for rhinovirus during natural colds.

Rhinoviruses (RV) cause 50% of common colds and are frequently isolated from children and adults hospitalized for asthma exacerbations. Although colds may trigger severe coughing and wheezing, it is not known whether these symptoms are a result of lower airway infection with RV. Previous efforts to address this question by sampling lower airway secretions during experimental RV infections have been complicated by the possibility of contamination of the bronchoscope with nasopharyngeal cells and secretions. To further test the hypothesis that RV infections involve the lower airways, tracheal and nasal secretions were obtained from 23 pediatric tracheostomy patients, including seven with cold symptoms and 16 asymptomatic controls. RV was detected by reverse-transcription polymerase chain reaction from the nasal and tracheal secretions of three of the seven children with cold symptoms. In the 16 well children, RV was not detected in any samples of nasal secretions, but was isolated from four samples of tracheal secretions. These results demonstrate the presence of RV in the lower airways of children with tracheostomies during community-acquired colds, without the possibility of nasal contamination. In addition, these findings suggest that children with tracheostomies carry subclinical viral infections in their tracheas, rather than their noses.

Adolescent↗
PubMed1992

Association of the human invariant chain with H-2 Db class I molecules.

We describe two proteins of 24 kDa and 33 kDa (p24 and p33) which associate with H-2 Kb and H-2 Db molecules, respectively, in human cells transfected with H-2 Kb and H-2 Db genes. This association is particularly clear in the mutant cell line T2, in which association of endogenous peptide with newly synthesized class I molecules may not occur (V. Cerundolo et al., Nature 1990. 345: 449). We show that p33 is the 33-kDa form of the human invariant chain which is resident in the endoplasmic reticulum of T2 cells (P. Cresswell, Cold Spring Harbor Symp. Quant. Biol. 1989. LIV:309). The stability of the invariant chain H-2 Db complex is critically dependent upon occupation of the class I binding site by peptide ligand. In the absence of peptide, the complex is stable at 4 degrees C whereas following exposure to peptide, the invariant chain dissociates rapidly from H-2 Db molecules (half-life of 30 min at 4 degrees C). Although the interaction between the human invariant chain and murine H-2 Db is unlikely to have any functional significance, the peptide-induced dissociation of the invariant chain is consistent with a conformational change in H-2 Db on peptide binding.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1994

Vascular responses in chain saw operators.

The intensive use of chain saws is associated with development of the hand-arm vibration syndrome (vibration white finger). Objective testing for cold induced vasospasm was carried out on the fingers of 12 chain saw operators and 12 matched control men from a similar working environment. Two of the chain saw operators tested positive for vasospasm in the laboratory and another three had an abnormal result. All of the control subjects tested negative. Measurements of finger blood flow at different temperatures and during vibration of the hand were similar in the chain saw operators and controls. Use of the chain saw did not cause significant alterations in the plasma concentrations of von Willebrand factor antigen in either the long or the short term.

Adult↗
PubMed1979

Structural studies of natural actomyosin from thermally acclimated frogs.

Natural actomyosin was isolated from skeletal muscle of frogs (Rana catesbeiana) acclimated at 25 degrees C and 5 degrees C. It was found that preparations isolated from warm-acclimated frogs may display considerable degradation of myosin heavy chains as compared with preparations isolated from cold-acclimated frogs. However, degradation may be minimized by inclusion of protease inhibitors during purification, indicating enhanced protease activity in preparations of natural actomyosin from warm-acclimated frogs. When purified in the presence of protease inhibitors, natural actomyosin from both warm-acclimated and cold-acclimated frogs exhibits comparable subunit composition of SDS-gel electrophoresis. The overall gel pattern is similar to that obtained from rabbit natural actomyosin except that in the frog, troponin-T and troponin-C appear to co-migrate with tropomyosin and myosin light chain 2, respectively.

Acclimatization↗
PubMed2000

Analysis of hemoglobin and globin chain variants by a commonly used capillary isoelectric focusing method.

To analyze both hemoglobin (Hb) and globin chain variants, we modified a commonly used method, capillary isoelectric focusing (CIEF), with detection at 280 nm. The samples were hemolysates prepared from red blood cells, and globin chains obtained from the hemolysates by treatment with cold acidified acetone. When the migration time for the internal reference, carbonic anhydrase I (isoelectric point, pI 6.60), was taken as 1.0, the migration ratio for Hb A0 in normal human blood was 0.877 +/- 0.004 (mean +/- SD, n = 9), and those of the alpha- and beta-globin chains were 0.673 +/- 0.004 and 0.847 +/- 0.005 (mean +/- SD, n = 4), respectively. The ratio of peak heights between the beta- and alpha-globin chains (beta/alpha) in the normal Hbs obtained from four subjects was almost constant at 2.5 +/- 0.1 (mean +/- SD). This ratio indicates which of the globin chains includes a mutation (if one exists). When an Hb variant, Hb Hoshida (in which Gln is substituted for Glu at residue 43 in the beta-globin chain), was analyzed by this method, two main peaks were observed (migration ratios 0.836 and 0.877, corresponding to an abnormal and the normal Hb, respectively). An additional peak with an abnormal migration ratio of 0.788 was also detected in the globin chain profiles. The ratio of peak heights between normal beta- and alpha-globin chains was 1.57, indicating that a mutation exists in the beta-globin chain. We thus established a convenient system using CIEF that provides a rapid and reproducible method for the random analysis of both Hb and globin chain variants.

Electrophoresis, Capillary↗
PubMed1988

Influence of cold exposure on liver amino acid metabolism enzymes of the rat.

The activities of alanine, aspartate and branched-chain amino acid transaminases, glutamate dehydrogenase, glutamine synthetase and adenylate deaminase have been studied in liver of male rats exposed [12 hours at 4 degrees C] or acclimated [15 days at 4 degrees C] to cold temperature. Cold temperature induced an increase of the activities of glutamate dehydrogenase and alanine and aspartate transaminases both in cold-exposed and cold-acclimated animals; adenylate deaminase activity diminished after 15-day cold acclimation. There were not significant changes induced by cold temperature in the activities of the other two enzymes studied. These results agree with a possible direct implication of amino acid utilization by the liver in the context of the overall thermogenic response to cold temperature.

AMP Deaminase↗
PubMed2000

Sympathetic control of glucagon receptor mRNA levels in brown adipose tissue of cold-exposed rats.

Brown adipose tissue (BAT) is implicated in both cold-induced thermogenesis and regulation of energy expenditure and is mainly controlled by sympathetic innervation. To clarify the permissive and/or complementary roles of glucagon in cold-induced BAT activation, glucagon receptor gene expression and its modulation by sympathetic activity were investigated in rats. One pad of interscapular BAT was surgically denervated while the other pad was sham operated, then rats were either cold-exposed (CE) for 1 week at 4 degrees C or kept near thermoneutrality (25 degrees C, TN). Using a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay, it was shown that cold exposure decreased (-44%) the relative abundance of BAT glucagon receptor mRNA, an effect which was prevented by unilateral surgical sympathectomy of BAT. The present results show a negative control by sympathetic nervous activity of glucagon receptor gene expression and/or of glucagon receptor mRNA stability in BAT of cold-exposed rats. The down-regulation of glucagon receptor expression during cold exposure does not support a major role of the peptide in the thermogenic control of BAT.

Adipose Tissue, Brown↗
PubMed2003

Detection of mitochondrial electron chain carrier redox status by transhepatic light intensity during rat liver reperfusion.

The aim of the study was to investigate mitochondrial electron transfer during rat liver reperfusion after cold storage and hypothermic machine perfusion. Livers from male Brown Norway rats were preserved (UW) for 10h either by cold storage (CS) or by hypothermic oxygenated perfusion extracorporal (HOPE). Transhepatic photometric analysis allowed determination of the redox status of mitochondrial cytochromes during preservation, rewarming and reperfusion. Mitochondrial electron chain carriers were inhibited at different sites with rotenone and cyanide in some experiments. reversed transcriptional polymerase chain reaction (RT-PCR) was performed after reperfusion concerning transcription of TNFalpha, caspase 9, and c-jun kinase (JNK). Increased superoxide anion formation as well as transcription of TNFalpha, caspase 9, and JNK during reperfusion after cold storage (CS) were related with completely reduced cytochromes before and during reperfusion. In contrast, hypothermic oxygenated livers (HOPE) showed oxygenated cytochromes as well as decreased superoxide anion formation and no detectable transcription of TNFalpha, caspase 9, and JNK. A similar low level of superoxide anion formation was found when electron chain transfer of cold stored livers was inhibited during reperfusion with rotenone but not with cyanide. After hypothermic oxygenation (HOPE) inhibition of mitochondrial electron chain with rotenone showed no change in formation of superoxide anion formation whereas inhibition with cyanide showed increased superoxide anion formation. Thus mitochondrial cytochrome redox status is suggested to be related: (i) with the release of reactive oxygen substances as well as (ii) with the expressions of TNFalpha, caspase 9, and JNK during reperfusion and may thus be usable as predictive marker of liver grafts.

Animals↗
PubMed1994

Thermodynamics of staphylococcal nuclease denaturation. II. The A-state.

Staphylococcal nuclease, at low pH and in the presence of high salt concentrations, has previously been proposed to exist in a partially folded or molten globule form called the "A-state" (Fink et al., 1993, Protein Sci 2:1155-1160). We have found that the A-state of nuclease at pH 2.1 in the presence of moderate to high salt concentrations and at low temperature exists in a substantially folded form structurally more similar to a native state. The A-state has the far-UV circular dichroism spectra characteristic of the native protein, which indicates that it has a large degree of secondary structure. Upon heating, the A-state denatures with a sigmoidal change in far-UV ellipticity and an observable peak in a differential scanning calorimeter trace, indicating that it is thermodynamically distinct from the denatured state. Three different mutations in a residue normally buried in the protein's core stabilize or destabilize the A-state in the same way as they affect the denaturation of the native state. The A-state must, therefore, contain at least some tertiary packing of side chains. Unlike the native state, which shows cold denaturation at low temperatures, the A-state is most stable at temperatures below 0 degrees C.

Calorimetry, Differential Scanning↗
PubMed1991

Tetanus toxin receptor. Specific cross-linking of tetanus toxin to a protein of NGF-differentiated PC 12 cells.

A subclone of rat pheochromocytoma cells expresses high affinity receptors for tetanus toxin on differentiation with NGF [Walton, K.M., Sandberg, K., Rogers, T.B. and Schnaar, R.L. (1988) J. Biol. Chem. 263, 2055-2063]. In the presence of protein cross-linking agents, [125I]tetanus toxin, bound to these cells at 0 degree C, forms a cross-linked product with apparent molecular weight of 120 kDa. The formation of [125I]tetanus toxin conjugate involves the heavy chain of the toxin, is prevented by cold toxin and it is largely reduced by pretreating cells with proteases. The cross-linked product is formed only upon incubation of the toxin with NGF-differentiated cells. These results suggest that a protein with apparent molecular weight of 20 kDa is involved in the neurospecific binding of tetanus toxin.

Animals↗
PubMed2001

Cryptoregiochemical analysis of an unusual bacterial desaturation.

The cryptoregiochemistry of the cold-induced Delta(5) desaturation of long chain fatty acids, as it occurs in Bacillus subtilis ATCC 23857, has been examined by measuring the individual primary deuterium kinetic isotope effects associated with the C-H bond cleavage at C-5 and C-6. The results point to C-5 as the site of initial oxidation in Delta(5) desaturation.

Bacillus subtilis↗
PubMed1993

Omega-3 fatty acid modification of membrane structure and function. II. Alteration by docosahexaenoic acid of tumor cell sensitivity to immune cytolysis.

Docosahexaenoic acid (DHA, 22:6) is a long-chain omega-3 fatty acid abundant in cold water fish; it is the most unsaturated fatty acid found in biologic systems and is reported to alter membrane structure. To explore DHA's effect on membrane function, we have fused tumor cells with synthetic phosphatidylcholine (PC) containing stearic acid in the sn-1 position and DHA in the sn-2 position (18:0, 22:6 PC) and have found the lipid-modified tumor cells to be more sensitive to cytolysis by alloreactive cytotoxic T lymphocytes. Cold target competition experiments suggested that fusion of tumor plasma membranes with 18:0, 22:6 PC produced a qualitative change in expression of surface antigens recognized by cytotoxic T lymphocytes. We monitored the expression of various epitopes on tumor cells by complement-mediated lysis and radioimmunoassay with monoclonal antibodies against H-2 class I antigens. Our results suggest that membrane-bound DHA increases the expression of some epitopes while decreasing the expression of others and that different tumor lines vary in the magnitude of DHA's effect. Our findings are consistent with a model in which DHA-containing phospholipids segregate into membrane domains, in turn altering the expression of membrane proteins.

Animals↗
PubMed1995

Cu-pyruvaldehyde-bis(N4-methylthiosemicarbazone) (Cu-PTSM), a metal complex with selective NADH-dependent reduction by complex I in brain mitochondria: a potential radiopharmaceutical for mitochondria-functional imaging with positron emission tomography (PET).

The reductive retention mechanism of copper(II)-pyruvaldehyde-bis (N4-methylthiosemicarbazone) (Cu-PTSM), a generator-produced positron-emitting 62Cu-labeled radiopharmaceutical, was studied with non-radioactive and radioactive copper. Changes in the chemical form of Cu-PTSM were detected by electron spin resonance spectrometry (ESR) with cold copper. The effects of electron transport chain inhibitors on the reduction of Cu-PTSM were also examined. Rotenone and antimycin A activated the reduction of Cu-PTSM in the brain mitochondria by 1.6- and 1.4-fold, respectively, compared with untreated controls, while thenoyltrifluoroacetone (TTFA) had no effect on the reduction. These results were confirmed with radioactive copper. Furthermore, this reduction of Cu-PTSM was dependent on the protein concentration of mouse brain submitochondrial particle (SMP) with 1 mM NADH (0 mg-protein/ml: 1.8 +/- 2.5%, 8 mg-protein/ml: 69.0 +/- 5.5%, each value was % of reduced Cu). Similarly, this reduction depended on NADH concentration at a fixed concentration of SMP (8 mg-protein/ml). These results indicated that the electron transport chain, especially complex I, participated in the reduction of Cu-PTSM in brain mitochondria, and this suggested that Cu-PTSM has the potential to act as a functional imaging agent for diagnosis of the electron transport chain.

Animals↗
PubMed1999

Cold agglutinins in low-grade B-cell lymphoma.

The presence of serum cold agglutinin can be the initial presentation of lymphoproliferative diseases. Conditions with persistent cold agglutinins are a spectrum of diseases that vary from benign lymphoproliferation of the "autoimmune-like chronic cold agglutinin disease" to malignant lymphoma. We report a case of a 72-year-old woman who presented with severe anaemia, hepatosplenomegaly and episodes of peripheral haemagglutination precipitated by cold exposure. The haemoglobin was 5.6 g/dL with a cold agglutinin titer of 1:256 at 4 degrees C and 1:8 at room temperature (30 degrees C). The cold agglutinin showed anti-I specificity and kappa light chain restriction. Peripheral blood showed atypical lymphoid cells with a B-cell immunophenotype. Immunoglobulin gene rearrangement study by polymerase chain reaction (PCR) showed an amplified band at 100 bp, consistent with a clonal proliferation of B-lymphocytes. We believe that our patient had cold antibody haemolytic anaemia as the initial presentation of a low-grade non-Hodgkin's lymphoma. The association of cold antibody haemolytic anaemia with low-grade B-cell lymphoma is unusual.

Aged↗
PubMed1994

Effects of palmitoyl carnitine and related metabolites on the avian Ca(2+)-ATPase and Ca2+ release channel.

1. In birds, prolonged cold exposure induces the development of a non-shivering thermogenesis (NST) of muscular origin that may result from an increase in ATP-dependent cycling of Ca2+ between the sarcoplasmic reticulum (SR) and the cytosol. 2. Because fatty acids are thought to play a significant role in NST, we investigated the effects of palmitic acid and related metabolites on skeletal SR Ca2+ uptake and release in ducklings. 3. Ca(2+)-ATPase activity, 45Ca2+ release and [3H]ryanodine-binding measurements indicated that palmitic acid was without effect on the Ca(2+)-ATPase and Ca2+ release channel. Palmitoyl carnitine and palmitoyl coenzyme A inhibited the Ca(2+)-ATPase at concentrations > 20 microM whereas both activated the Ca2+ release channel at concentrations < or = 20 microM in a dose-dependent manner. 4. Palmitoyl carnitine stimulated [3H]ryanodine binding to skeletal but not cardiac SR vesicles. Induction of 45Ca2+ release was observed with long-chain (C > or = 14) but not with short-chain acyl carnitines (C < or = 12). 5. Long-chain acyl carnitines accumulated significantly in duckling skeletal muscle during cold acclimation. Accordingly, these results suggest that long-chain acyl metabolites may modulate SR Ca2+ cycling and its associated thermogenesis in vivo.

Animals↗
PubMed2000

Prevention of proteolysis in cold-stored rat liver by addition of amino acids to the preservation solution.

BACKGROUND: One process identified as detrimental in liver preservation is proteolysis. METHODS: We tested the effects of adding antiproteolytic amino acids (L-alanine, L-glutamine, L-histidine, L-leucine, L-methionine, L-phenylalanine, L-proline, L-tryptophan) to the preservation medium, in a model of reperfusion of 24 h cold-stored rat livers. RESULTS: During the preservation period, antiproteolytic amino acids inhibited the proteolysis observed in stored livers as shown by branched-chain amino acid fluxes, which switched from release to uptake. During reperfusion, cold storage of lives without the addition of antiproteolytic amino acids resulted in a decrease in the total amino acid and branched-chain amino acid uptake and a lower perfusion flow rate. The addition of antiproteolytic amino acids during liver storage resulted in the maintenance of total amino acid and branched-chain amino acid uptake and a significant improvement in the perfusion flow rate during reperfusion. CONCLUSIONS: The presence of antiproteolytic amino acids in the preservation medium might be of interest in improving hepatic graft viability in transplantation.

Amino Acids↗
PubMed2000

[The correlation between the exacerbation of bronchial asthma and picornavirus (human rhino virus) infection in throat gargles by RT-PCR].

Viral infection is one of important factors to cause the exacerbation of bronchial asthma. We have investigated 167 adults of asthmatics to clarify the correlation between viral infection and exacerbation of asthma. Patients were classified to four group by the symptoms of common cold and asthma attack. Furthermore, we have examined Picornavirus and Human rhino virus RNA from throat gargles of patients using RT-PCR (reverse transcription--polymerase chain reaction) method. Forty of 65 (61.5%) asthmatics with common cold revealed asthma attack and common cold was significantly associated with acute exacerbation of asthma (p < 0.01). We identified Picornavirus RNA, which include 113 of Human rhino virus serotypes and enterovirus, from the samples of 16 of 52 (30.8%) patients who had acute exacerbation. It was significantly higher than the detection rate of viral RNA from patient without asthma attack. Furthermore, we analyzed Human rhino virus RNA from the same samples by RT-PCR and 93.7% of Picornavirus were identified as Human rhino virus. Taken together, these findings suggest that common cold is significantly associated with the exacerbation of bronchial asthma. Human rhino virus infection might be one of important virus in this procedure.

Adult↗