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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolated small intestine epithelial cells were prepared by using either (a) hyperosmolar, low sodium, high potassium containing (intracellular-like) solutions, or (b) isosmolar, high sodium, low potassium containing (extracellular-like) solutions. Both (a) and (b) cells show high viability as estimated by Trypan blue exclusion, oxygen consumption, cellular ATP content, lactate-dehydrogenase liberation, intracellular ion concentrations and significant Na+-dependent alanine and uridine uptakes. Although (a) and (b) cells show in the cold similar ion concentration, after reincubation at 37 degrees C for 30 min (a) cells show intracellular ion concentrations of 31 mM Na, 129 mM K and 88 mM Cl, whilst (b) cells have 71 mM Na, 93 mM K and 102 mM Cl. Cells prepared with (a) concentrate much more alanine and uridine than cells prepared with (b), probably because the latter have a lower Na+ gradient across the plasma membrane. Cells prepared with intracellular-like solutions would be an ideal system to study Na+-dependent transport mechanisms and the regulatory systems of intracellular ion concentrations.
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PMID:The use of hyperosmolar, intracellular-like solutions for the isolation of epithelial cells from guinea-pig small intestine. 360 46

The interrelation between the energy and nitrogenous metabolism of the myocardium during cardioplegia has been studied in patients with congenital valvular heart disease (tetralogy of Fallot--12 patients, ventricular septal defect--5 patients). Whole body hypothermia with repeated heart reperfusion with cold cardioplegic blood perfusate was used for the protection of the myocardium. However, ATP level of the myocardium of some patients decreased by 20% and more of the baseline. This loss was accompanied by a reduction in glutamate and aspartate levels and a rise in ammonium and alanine levels in the myocardium (by 17.7 +/- 3.8; 17.6 +/- 5.9; 61.4 +/- 12.5 and 92.4 +/- 26.3% of the baseline, respectively).
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PMID:[Effect of cardioplegia on nitrogen and energy metabolism of the human heart]. 366 4

The role of glucocorticoids in the increase by cold-exposure of the effect of alanine on the malate-aspartate shuttle was studied in perfused rat liver. The capacity of the shuttle was evaluated by measurement of changes in both the rate of glucose production from sorbitol and the ratio of lactate to pyruvate during ethanol oxidation (Biomed. Res. 6, Suppl., 1986). The effect of alanine on the shuttle capacity was decreased by adrenalectomy. When 1.5 mg/kg dexamethasone sulfate was administrated to adrenalectomized rats kept at 24 or 4 degrees C, once daily for 5 days, the effect of alanine on the shuttle increased its capacity to the level of sham-operated rats that had been exposed to 4 degrees C for 5 days. The effects of dexamethasone were blocked by the coadministration of tetracycline with the agent. Cold exposure and steroid replacement had little effect on the alanine-induced elevation of the levels of aspartate, glutamate, and alpha-ketoglutarate in liver cells. The increase of the effect of alanine could not be explained only by changes in the activity of NAD+ malate dehydrogenase and aspartate aminotransferase. The results suggest that cold exposure and replacement treatment with glucocorticoids modulate equally the effect of alanine on the capacity of the malate-aspartate shuttle.
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PMID:Effects of alanine on malate-aspartate shuttle in perfused livers from cold-exposed rats. 376 24

Human adenovirus fails to multiply efficiently in monkey cells owing to a block to late viral gene expression. Ad2hr400 through Ad2hr403 are a set of host range (hr) mutants which were selected for their ability to readily grow in these cells at 37 degrees C. The mutations responsible for this extended host range have previously been mapped to the 5' portion of the gene encoding the 72-kilodalton DNA-binding protein (DBP). DNA sequence analyses indicate that all four hr mutants contain the same alteration at coding triplet 130, which changes a histidine codon to a tyrosine codon. These results extend those of Anderson et al. (J. Virol. 48:31-39, 1983), which suggested that only this change in the DBP amino acid sequence can expand adenovirus host range to monkey cells. The hr phenotype does not appear to require phosphorylation of this tyrosine residue, since no phosphotyrosine was detected in DBP isolated from Ad2hr400-infected monkey cells. The hr mutants Ad2hr400 through Ad2hr403, however, are cold sensitive for growth in monkey cells. The mutant Ad2ts400, which was derived from Ad2hr400, represents a second class of hr mutants which can grow efficiently in monkey cells at 32.5 degrees C. The cold-resistant hr mutation of Ad2ts400 has previously been mapped to the 5' region of the DBP gene (map units 63.6 through 66). DNA sequence analysis of this region shows that this mutant contains the original hr alteration at coding triplet 130 as well as a second alteration at coding triplet 148, which changes an alanine codon to a valine codon. We suspect that the alterations at amino acids 130 and 148 change the structure of the amino-terminal domain of the DBP, allowing it to better interact with monkey cell components required for late viral gene expression. Ad2ts400 also contains a temperature-sensitive mutation which has previously been mapped to the 3' portion of the DBP gene (map units 61.3 through 63.6). Sequence analysis of this region indicates that the DBP coding triplet 413 has been altered. This change from a serine codon to a proline codon is the same alteration reported in the previously sequenced DBP mutants Ad5ts125 (W. Kruijer et al., Nucleic Acids Res. 9:4439-4457, 1981) and Ad5ts107 (W. Kruijer et al., Virology 124:425-433, 1983). Thus it appears that only a very limited number of changes in either the 5' or the 3' portion of the DBP gene can give rise to the hr or temperature-sensitive phenotypes, respectively.
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PMID:Restricted changes in the adenovirus DNA-binding protein that lead to extended host range or temperature-sensitive phenotypes. 392 61

The exit of glutamate from Escherichia coli K-12 cells preloaded with the radioactive amino acid and its relation to the reaction of entry were studied. Experiments with cells preloaded to different intracellular concentrations of radioactive glutamate confirmed our earlier conclusion that glutamate exit was a first-order reaction. l-Glutamate, competitive inhibitors of glutamate uptake (d-glutamate and l-glutamate-gamma-methyl ester), noncompetitive inhibitors of glutamate uptake (l-serine and l-alanine), and the energy poison NaN(3) all accelerated glutamate exit 2.8-fold. No additive effect was observed in the presence of NaN(3) together with l-glutamate. Preloading with cold l-glutamate did not increase the rate of uptake of radioactive glutamate. It is concluded that the acceleration of glutamate exit in the presence of l-glutamate in the medium is not due to exchange diffusion and that l-glutamate and azide affect exit indirectly by preventing recapture. Sucrose, 25%, slowed down glutamate exit by a factor of about 4.7 and increased the steady-state level of glutamate accumulation to about the same extent. Increasing the intracellular K(+) concentration enhanced glutamate uptake but did not affect the half-time of exit. It is concluded that separate carriers are most probably involved in mediating the entry and exit reactions.
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PMID:Glutamate transport in Escherichia coli K-12: nonidentity of carriers mediating entry and exit. 456 40

Teichoic acid-like material extracted by cold trichloroacetic acid from lyophilized whole cells of streptococci from groups A,D,E,O, and T was shown to give a positive precipitin reaction with group antisera. Similar material from cells of groups B,C,F,G,H,K,L,M,N,P,Q,R, and S did not give a positive reaction with group antisera. The group A material also reacted with anti-E serum; however, the opposite did not occur. A similar result was also obtained on the group T material and anti-O serum. The group A teichoic acid was purified by Sephadex column chromatography, and was shown to be free of cell wall peptidoglycan and polysaccharide, and ribitol teichoic acid. It was composed of glycerol, phosphate, alanine, and glucosamine. Alkaline hydrolysis showed the presence of ester-linked alanine and glucosaminylglycerol. Phosphorus was released from ester linkage by alkaline phosphatase. N-acetylglucosamine produced a 72% inhibition of the precipitin test at a level of 10 mumoles, and d-alanine methyl ester was significantly stronger than the l-alanine ester. A single precipitin band was seen with group A serum. The data indicate that teichoic acid of group A streptococci is a polymer composed of glycerol phosphate and containing N-acetylglucosamine and alanine. Antisera to these streptococci contain antibodies specific for the alanine and the glucosamine linkages. The use of serum containing antibodies to alanine-polyglycerophosphate shows that the occurrence of this type of teichoic acid is widespread among the streptococci.
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PMID:Composition and properties of a group A streptococcal teichoic acid. 498 40

Uptake of valine by Arthrobotrys conoides was an active process and was independent of its incorporation into cellular protein. Chemical fractionation of cells supplied with (14)C-l-valine for different time intervals revealed that the amino acid initially entered a pool of metabolic intermediates and was extractable with cold trichloroacetic acid. After a 4-min interval, some intracellular valine was incorporated into cell proteins, but most underwent metabolic transformation to a variety of products that included carboxylic acids and other amino acids. Carbon derived from valine was not localized in the lipid or nucleic acid fraction of cells, but some was completely oxidized and recovered as metabolic (14)CO(2). Autoradiograms of paper and thin-layer chromatograms of acid hydrolysates of cellular protein identified the following amino acids as having originated from valine: glutamate, aspartate, alanine, and leucine. Similar analysis of cold trichloroacetic acid extracts established that (14)C supplied as l-valine had been transformed also to alpha-ketoisovalerate, isobutyrate, propionate, succinate, malate, oxalacetate, pyruvate, and alpha-ketoglutarate. Pathways for transformation of the carbon skeleton of valine to various metabolic products are proposed.
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PMID:Metabolism of valine by the filamentous fungus Arthrobotrys conoides. 546 79

1. Cells of Euglena gracilis grown in the dark on high ratios of carbon source to nitrogen source (;high-carbon cells') are unable to form chlorophyll during a subsequent incubation in the light; cells grown in the dark on low ratios of carbon to nitrogen (;low-carbon cells') synthesize chlorophyll at a rapid rate during the subsequent incubation in the light. High-carbon cells will form chlorophyll rapidly if supplied with a nitrogen source during the incubation in the light: of the nitrogen sources tested, ammonium sulphate was the most effective at overcoming the block in chlorophyll synthesis. The nitrogen source does not have to be present during the actual incubation in the light: a 5hr. exposure of high-carbon cells to ammonium sulphate in the dark, followed by removal of the nitrogen source, is sufficient to bring about rapid chlorophyll synthesis during a subsequent incubation in the light. 2. The synthesis of chlorophyll by low-carbon cells exposed to the light is strongly repressed by the addition of ethanol or other utilizable carbon sources during the incubation in the light. Chlorophyll synthesis ceases altogether between 5 and 10hr. after the addition of the carbon source. Carotenoid synthesis is also inhibited, but to a smaller extent. The inhibitory effects of ethanol are prevented if ammonium sulphate is added at the same time. 3. High-carbon cells contain about four times as much carbohydrate per cell and about twice as much lipid per cell as low-carbon cells. The content per cell of total protein, soluble protein and DNA are about the same in both types of cell. The low-carbon cells sometimes, but not always, contain more RNA than the high-carbon cells. Analysis of cold-acid extracts indicates that the two kinds of cells contain about the same concentrations of pool amino acids, but that the low-carbon cells contain somewhat higher concentrations of peptides in the pool. Ion-exchange analysis of pool extracts shows a number of differences between high-carbon and low-carbon cells with respect to the concentrations of individual amino acids: in particular low-carbon cells contain higher concentrations of alanine. High-carbon cells have approximately twice as much protease activity as low-carbon cells. 4. The possible biochemical basis for the differing ability of high-carbon and low-carbon cells to form chloroplasts in the light is discussed.
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PMID:Control of chloroplast formation in Euglena gracilis. Antagonism between carbon and nitrogen sources. 580 91

Cholecystokinin (CCK)-like immunoreactivity (CCK-LI) in a pool of 12 dog brains was extracted sequentially into boiling water and cold 2% trifluoroacetic acid. Gel filtration on Sephadex G-50 revealed three main molecular forms detected by a carboxyl-terminal antibody; one was eluted in the position of CCK-58 (58 amino acid residues long); a second, in the position of CCK-8; and a third, near the radioactive iodide marker. When the CCK-LI was purified by affinity chromatography using carboxyl-terminal CCK antibody followed by three steps of reversed-phase high-pressure liquid chromatography, three components were isolated and characterized by sequence microanalysis. The smallest component was the pentapeptide common to gastrin and CCK. The second peak was eluted in the same region as synthetic CCK octapeptide, and sequence analysis showed that the chemical structure of this biologically active region of canine CCK is identical to that found in sheep and pig brains. The 22-residue amino-terminal sequence of brain CCK-58 was: Ala-Val-Gln-Lys-Val-Asp-Gly-Glu-Pro-Arg-Ala-His-Leu-Gly -Ala-Leu-leu-Ala-Arg-Tyr-Ile-Gln-, the same as the sequence found for canine intestinal CCK-58 from this pool of dogs. This is the same sequence others have reported for porcine brain CCK-58 lacking nine amino acid residues (CCK-58 desnonapeptide) except that the porcine peptide had a serine in position 9. The canine CCK amino-terminal sequence differed from the sequence Ala-Gln-Lys-Val-Asn-Ser previously reported for intestinal CCK-58 purified from another pool of dog tissue, but the rest of the residues identified were identical in the two peptides. CCK-58 may be a molecular precursor of the smaller forms of CCK in brain as well as in gut.
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PMID:Isolation of a large cholecystokinin precursor from canine brain. 609 6

(Na,K)-ATPase is thought to maintain the transmembrane electrochemical sodium gradient which powers secondary active sodium-coupled transport of a variety of solutes including amino acids and bile acids. However, little is known regarding the effect of sodium-coupled solute transport on intracellular sodium concentration ( [Na]ic) and on (Na,K)-ATPase-mediated cation pumping in the intact cell. In order to address this question, we have measured 22Na uptake rate, steady state 22Na content, and ouabain-suppressible 86Rb uptake rate in primary cultures of adult rat hepatocytes under a variety of conditions. Compared with control conditions (sodium uptake rate = 6.00 +/- 0.40 nmol X min-1 X mg-1; [Na]ic = 11.96 +/- 0.54 mM; cation pumping = 2.53 +/- 0.18 nmol X min-1 X mg-1), cation pumping was increased by taurocholate (less than or equal to 158%), alanine (less than or equal to 246%), monensin (less than or equal to 400%), and cold exposure (less than or equal to 525%), and this increase was accompanied by increases in Na uptake and [Na]ic. In contrast, preincubation in low sodium medium decreased all three variables. These changes in cation pumping were blocked in the absence of extracellular sodium and were not accompanied by changes in ouabain-suppressible ATP hydrolysis measured in cell homogenate. An overall plot of cation pumping versus [Na]ic yielded a sigmoid-shaped curve. Values for KNa (17.8 +/- 1.4 mM) and Vmax (8.98 +/- 0.62 nmol X min-1 X mg-1) for cation pumping were estimated assuming three sodium sites per pump unit. These findings indicate that: 1) uptake of alanine and taurocholate is associated with a rapid increase in (Na,K)-ATPase cation pumping; 2) this increase probably results from an increase in pumping per pump unit rather than an increase in the total number of pump units, and it appears to be mediated via an increase in sodium influx and [Na]ic; 3) [Na]ic under control conditions is close to the apparent KNa of cation pumping, implying that substrate availability may be the mechanism whereby sodium uptake is tightly linked to (Na,K)-ATPase cation pumping in intact hepatocytes.
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PMID:(Na,K)-ATPase-mediated cation pumping in cultured rat hepatocytes. Rapid modulation by alanine and taurocholate transport and characterization of its relationship to intracellular sodium concentration. 613 54


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