Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously, we have demonstrated that hearts preserved ex vivo for 12 hours maintain normal hemodynamic performance after orthotopic transplantation. To complete our studies of these preserved hearts, we evaluated myocardial metabolism by determining high energy phosphate levels and catecholamine concentrations in 22 canine hearts. Group I was the control group in which six hearts were given cold cardioplegic solution; full thickness biopsies were taken from the myocardium in two areas of the right and left ventricles and septum; and adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, creatine phosphate, and catecholamines were determined. Group II, in which the hearts were preserved 12 hours, had eight hearts that were stopped with cold cardioplegic solution, excised, and then preserved in an ex vivo state with a 32 degrees C modified blood perfusate. After a 12-hour perfusion period, the hearts were stopped and biopsies taken. Group III involved cold ischemia and had six hearts that were stopped with cardioplegic solution, excised, opened, flushed, and stored for 2.5 hours at 2 degrees to 4 degrees C. Biopsies were obtained as in groups I and II. Adenosine triphosphate levels were slightly reduced in the 12 hour preserved heart when compared with the control group and the heart in the cold ischemia group preserved for 2.5 hours (p less than 0.01). Creatine phosphate levels were significantly elevated after 12 hour preservation when compared with groups I and III (p less than 0.01). Hearts preserved by cold ischemia also had a reduction (p = 0.03) of creatine phosphate when compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:High energy phosphates and catecholamine stores after prolonged ex vivo heart preservation. 361 57

Conditions were developed to permit the extraction of branched-chain 2-oxoacid dehydrogenase from brain tissue in the state of phosphorylation in which it occurred in vivo. Tissue was cold clamped to prevent interconversion of the enzyme forms without rupturing mitochondrial membranes. Extraction was carried out in the presence of NaF to prevent dephosphorylation of the enzyme complex and in the presence of ADP to prevent phosphorylation. In adult male control rats, approximately 35% of the total enzyme from brain was present in the active form. In brains of diabetic rats, the active fraction was increased to 56%. Total activities did not differ in the two groups of rats.
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PMID:Diabetes increases active fraction of branched-chain 2-oxoacid dehydrogenase in rat brain. 374 6

Important advances have been made in recent years in the study of the structure of pyruvate kinase: the amino acid sequence of the enzymes from chicken muscle and yeast have been established and the three-dimensional structure of the cat muscle enzyme has been determined at 0.26 nm resolution. Work in our laboratory has shown that dialdehyde-ADP (oADP) can be used as an affinity label of rabbit muscle pyruvate kinase: if the enzyme is incubated with cold oADP in the presence of high ADP concentrations, dialyzed and then incubated with 14C-oADP, the enzyme inactivates and one mole of radioactive oADP incorporates per mole of enzyme subunit. A labeled peptide with a molecular weight of about 5900 has been purified from a tryptic digest of the modified enzyme. The first 26 residues of the peptide have been sequenced and this sequence is identical to a region in the chicken muscle enzyme and a peptide isolated from the bovine muscle enzyme specifically labeled with trinitrobenzenesulfonate. High homology is also found with a region of the yeast enzyme. All this suggests that the isolated peptide is part of the active site; the modified amino acid, probably a lysine, seems to be located in one of the alfa helices of domain A of the enzyme, according to the x-ray data.
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PMID:Pyruvate kinase: studies on affinity labeling and active-site structure using the rabbit muscle enzyme. 383 41

Platelets circulating in the human blood stream are smooth disk-shaped structures. The disks change within seconds of exposure to ADP or thrombin to irregular spheres bearing filopodia and pseudopodia. It is well-established that platelets also change shape (although more slowly) when chilled to 5 degrees C and revert to disks on rewarming. This cold-induced shape change may be due to the depolymerization of the submembranous microtubule ring. However, we found that chilling in the presence of Taxol, which stabilizes the microtubules, still results in shape change. Chilled platelets show an increase in the amount of myosin in the Triton-X insoluble residue or 'cytoskeleton' which is correlated in time both with phosphorylation of the myosin regulatory light chain and with the induced shape change. We suggest here that the slow cold-induced change from disks to spheres is due primarily to a gradual activation of myosin.
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PMID:Reversible association of myosin with the platelet cytoskeleton. 383 8

The effect of various nucleotide-enhancing agents on renal function and intracellular nucleotide levels was evaluated in a canine autotransplant model. Thirty-five dogs (18-28 kg) underwent left nephrectomy and 30 min of warm ischemia followed by Collins C-4 flush and 24 hr of cold-storage preservation. Heterotopic autotransplantation and immediate contralateral nephrectomy was then performed. Seven equal groups were evaluated: group A--controls, group B--adenosine pretreatment (1.0 g), group C--dipyridamole pretreatment (10 mg), group D--adenosine (1.0 g), and dipyridamole (10 mg) pretreatment, group E--adenosine (200 mg) and EHNA (2.5 mg/kg) pretreatment, group F--adenosine (200 mg) and EHNA (2.5 mg/kg) in the Collins C-4 flush, and group G--adenosine (200 mg) and EHNA (2.5 mg/kg) at the time of autotransplantation. All kidneys underwent cortical biopsies at the end of preservation and 1 hr after restoration of blood flow for determinations of AMP, ADP, and ATP. In the pretreatment groups (groups B through E) there was 60% graft survival whereas the controls (group A) and the groups treated after ischemia (groups F and G) had 0, 0, and 20% graft survival, respectively. In groups B and E, ATP levels were greater than controls after preservation and 1 hr after restoration of blood flow. Group C AMP and ADP levels and group D energy charge were greater than controls in the post-transplantation biopsies. Administration of adenosine and EHNA after ischemia was not associated with increased intracellular nucleotide levels. One hour post-transplantation biopsies demonstrated greater ability to regenerate cortical nucleotides in the surviving animals but no absolute value could be identified as a predictor of viability. In conclusion, pretreatment with adenosine, dipyridamole, and EHNA alone and in combination is beneficial in ischemically injured kidneys undergoing cold-storage preservation.
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PMID:An experimental evaluation of nucleotide enhancement techniques for kidney transplantation. 388 Aug 44

Glycerol-extracted rabbit psoas fibres were incubated at temperatures between -35 degrees C and +10 degrees C in a low-ionic-strength relaxing solution containing 50% ethyleneglycol, 100 microM [3H]MgATP, 1 mM [14C]mannitol and less than 0.01 microM Ca2+. The fibres were then rinsed in a solution containing 1 mM ATP and the bound nucleotide eluted in trichloroacetic acid; all these operations were carried out at the cold temperature. Residual bound nucleotide was eluted with trichloroacetic acid at room temperature. The fibres were found to bind approximately 180 microM nucleotide, which is consistent with binding to the enzymatic site of myosin. The eluate, obtained in the cold, was analysed on poly(ethyleneimine)-cellulose for its ATP and ADP content. At temperatures down to -22 degrees C most of the bound nucleotide was ADP and there was little variation of this fraction with temperature. As the temperature was lowered below -22 degrees C the ATP fraction rose sharply; by -35 degrees C it predominated. These results are similar in type to those found by Biosca et al. [(1984) Biochemistry 23, 1947-1953] on isolated subfragment 1, but are displaced to a much lower temperature range. Thus in a muscle fibre only a low thermal energy is needed for myosin to hold its nucleotide in a constant balance between ATP and ADP.
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PMID:Nucleotide binding by myosin in glycerol-extracted rabbit skeletal muscle fibres at temperatures between -35 degrees C and 10 degrees C. 394 82

The effects of alcohol injection (0.5 g . kg-1 i.v.) on the core cooling and rewarming rates, concentration of the adenine nucleotides, and the phosphorylation state of the adenylate system (ATP/ADP X P) were studied in the skeletal muscle of anesthetized rabbits immersed in ice-cold water. NaCl-injected rabbits immersed in ice-cold water were used as cold controls, alcohol-treated animals at room temperature (20 degrees C) as alcohol warm controls, and NaCl-injected animals at room temperature as anesthesia controls, respectively. The fall of core temperature to 32 degrees C in the alcohol-treated rabbits and the cold controls took about 40 min. During this time the temperature of the alcohol warm and anesthesia controls fell by about 1 degree C. No difference in the rewarming rate was observed between the alcohol-treated and cold control rabbits. Serum glucose concentration was elevated in the cold controls (from 5.9 to 8.3 mmol/l) but not in the alcohol-treated rabbits. Cold exposure reduced the phosphorylation state in the skeletal muscle of the alcohol-treated rabbits by 32% (P less than 0.05), but the decrease (6%) was not significant in the cold controls. After rewarming the phosphorylation state decreased in the above groups by 71% and 15%, respectively, as compared with the initial values. No significant changes in the phosphorylation state were found in the warm control animals. The redox state of the cytosol in the skeletal muscle or liver did not change, nor was there any change observed in the arterial pO2 or pCO2 concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Skeletal muscle activity of alcohol-treated rabbits in immersion hypothermia: adenine nucleotide concentrations and phosphorylation state. 399 38

Myocardial protection provided by 2 types of cold cardioplegic solution and by cold saline solution was compared experimentally in dogs on cardiopulmonary bypass. Techniques and solutions used simulated clinical conditions. Serial biopsies of myocardium were assayed for adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate. Maintenance and recovery of each phosphate was calculated as a percentage of the prebypass value for each type of solution; these values were used to compare the myocardial protection afforded by the 3 solutions. A difference in these values was not observed between the 2 types of cardioplegic solution; both values were greater than for the control solution, which may indicate improved myocardial protection with cardioplegic arrest.
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PMID:Comparison of crystalloid and sanguineous cardioplegic solutions in the dog. 402 10

Mitochondria from brown adipose tissue of cold-acclimated rats (6 degrees C) oxidize alpha-ketoglutarate at a rate twice that of controls (26 degrees C). In both groups, however, the phosphorus: oxygen ratio with alpha-ketoglutarate never exceeded unity, and it is essentially zero with either succinate or alpha-glycerophosphate. Adenosine triphosphatase activity of these mitochondria is very low and it is not stimulated by 2,4-dinitrophenol. In addition, both respiration and phosphorylation are unaffected by adenosine diphosphate, 2,4-dinitrophenol, bovine serum albumin, or glutathione. Endogenous respiration of tissue slices is not stimulated by 2-4-dinitrophenol. It is suggested that brown fat mitochondria are not capable of oxidative phosphorylation, but do phosphorylate at the substrate level. Since these findings provide an unusual example of electron transport by means of an energetically nonconservative pathway, their significance to thermogenesis by brown adipose tissue is particularly emphasized.
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PMID:Nonphosphorylating respiration of mitochondria from brown adipose tissue of rats. 422 65

1. In resealed human red cells loaded with Ca-EGTA buffer solutions it was found that the intracellular free Ca(2+) concentration for half saturation of the Ca transport system (which pumps Ca out of the cell) is equal to or smaller than 4 x 10(-6)M and thus closely agrees with the dissociation constant of the Ca + Mg activated membrane ATPase.2. The maximal rate of Ca transport from resealed cells to medium was found to be 0.148 +/- 0.009 mumole/ml. cells.min at 28 degrees C.3. The rate of Ca transport was unaffected by a variation of the extracellular Ca(2+) concentration from 3.10(-7) to 5.10(-3)M.4. Evidence is presented making it probable that the stoichiometric relation between Ca transported and ATP hydrolysed is 1:1 rather than 2:1.5. As the Ca transport is quite rapid even at half saturation and the passive leak for Ca negligible in intact cells it can be predicted that the steady-state cellular Ca(2+) concentration must be low, most probably less than 10(-6) mumole/ml. cells. Transport from cells containing 5.10(-7) mumole/ml. into blood plasma is thermodynamically compatible with the normal plasma Ca(2+) concentration and the normal cellular ATP, ADP and P(i) content.6. Treatment with the mercurial PCMBS in the cold for 15 hr allows to load red cells with 1 mumole Ca/ml. cells without destroying their ability to transport Ca after removal of the mercurial.7. It is shown that at high cellular Ca concentrations (0.1-3 mumole/ml. cells) about 50% of the total is free Ca(2+) on account of binding mainly to dialysable cell constituents.
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PMID:Dependence on calcium concentration and stoichiometry of the calcium pump in human red cells. 427 35


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