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

Highly purified sympathetic nerve vesicles isolated from bovine splenic nerves were treated by hypo-osmotic shocks, freeze-thawing or incubation in the absence or presence of ATP and MgCl. The vesicle preparations were then studied morphologically by electron microscopy and their content of noradrenaline (NA), and soluble proteins analyzed biochemically with special regard to dopamine beta-hydroxylase (DBH). Hypo-osmotic shocks released about 25 per cent of the NA and protein content and about 8 per cent of the DBH activity. This treatment induced swelling of the vesicles but their membranes remained unruptured and they still contained dense cores. Freeze-thawing released about 35 per cent of the NA, 25 per cent of the proteins and 11 per cent of the DBH. After the latter treatment some matrix material still remained in most vesicles but many were less stainable than the intact vesicles in cold control preparations. During incubation at 30 degrees C in an isotonic sucrose-phosphate medium for 30 min the vesicles released most of their NA and soluble DBH activity as well as much of their matrix density. After incubation at 37 degrees C for 30 min most vesicles appeared translucent. After incubation at 30 degrees C for 30 min in the presence of ATP and MgCl the vesicles lost most of their original NA content but retained their DBH activity and most of their matrix density. The results indicate that there is not always a correlation between NA content and retention of matrix density which suggests that DBH might be a component of a macro-molecular complex responsible for the staining reaction taking place in the maxtrix of NA depleted vesicles. This hypothesis is further supported by the finding of striking similarities between DBH isolated from chromaffin granules and the granular and fibrillar material surrounding the nerve vesicles after depletion.
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PMID:On the soluble phase of adrenergic nerve vesicles: correlation of matrix density and biochemical composition. 114 Oct 28

Young male rats, Wistar CF strain, weighing about 100 g, were fed during 14 days with a well-balanced diet, but containing either 275 p.p.m. nabame, either 600 p.p.m. thirame or 3 600 p.p.m. zinebe. The animals given the non-contaminated diet were the controls. On the evening before the experiment, they were all fasted and some of them, forced to walk during 18 hours in a restraint wheel. On the morning of the experiment, some of the rats which have not been working were placed in a cold room at + 4 degrees C, and some others were given an i.p. injection of 2,6 g glucose per kg body weight. The animals were then killed, those that received the glucose treatment 30 mn after the injection, the cold-exposed rats 90 mn after the beginning of their exposure. The redox and energy potentials of the liver tissue were determined after the enzymatic assay of the following liver metabolites : lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, ATP, ADP, AMP, inorganic phosphate. The thirame group rats had the smallest body weight and the lowest food intake. All the pesticides-exposed animals has a higher liver weight than predicted by their body weight. The pesticides-containing diets decreased liver lactate concentration and the lac/pyr ratio. Thirame was the more efficient and it partly impaired the glucose induced increase of the cytoplasmic redox potential, as estimated from the variation of the lac/pyr ratio. The pesticide-containing diets also lowered the liver concentrations of beta-hydroxybutyrate, acetoacetate, and their ratio. Last the pesticides, which but slightly modified the liver contents in adenine nucleotides and inorganic phosphate in the fasting state, increased the ATP fall following cold exposure and decreased the net ATP synthesis produced by glucose administration. The thirame diet was the more efficient in our experimental conditions, the zinebe diet the least one. It was concluded in our discussion that dietary dithiocarbamates either induced a hyperthyroidic status in the animal, or acted themselves as thyroxin-like compounds, because the liver metabolism was more directed towards heat production than towards that of chemical energy available for syntheses.
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PMID:[Energy metabolism in the liver of rats fed a diet contaminated with dithiocarbamates]. 119 Jun 41

Sulphate was rapidly bound by cell suspensions of Thiobacillus ferrooxidans. The binding was depressed by tetrathionate but was unaffected by Group VI anions, cysteine or methionine. Increasing uptake of sulphate was observed in cell suspensions incubated in the presence of ferrous iron. The bulk of 35S-sulphate was removed from the organisms by washing with dilute sulphuric acid and the remaining label was incorporated into cold trichloroacetic acid-soluble compounds. 35S-labelled adenosine 5'-sulphatophosphate was produced from ATP and 35S-sulphate by cell suspensions and in cell-free extracts. There was no evidence for the production of adenosine 3'-phosphate 5'-sulphatophosphate assayed by a very sensitive bioluminescence method.
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PMID:The uptake and assimilation of sulphate by Thiobacillus ferrooxidans. 120 Jul 36

Mouse L cells are rendered permeable to nucleoside triphosphates by a cold shock with a near isotonic buffer. These cells retain their morphologic integrity and use exogenously supplied nucleotides and deoxynucleotides to synthesize RNA and DNA. The newly synthesized DNA is nuclear and is the product of semiconservative replication. Incorporation of deoxynucleotides into DNA by thymidine kinase-deficient cells were used to conform rigorously that the exogenously supplied deoxynucleotides were incorporated into DNA without intermediate processing through nucleosides. DNA synthesis requires the presence of Na+, ATP, all 4 deoxynucleotides, and Mg2+. The reaction is inhibited by N-ethylmaleimide, p-hydroxymercuribenzoate and actinomycin D. Hydroxy-urea and arabinosylcytosine do not inhibit the reaction whereas cytosine arabinoside triphosphate shows competitive inhibition with the deoxynucleotides. These findings indicate that the permeable cell system can be used for in situ evaluations of the replicative DNA polymerase using the endogenous DNA template.
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PMID:DNA synthesis in permeabilized mouse L cells. 124 13

Madin-Darby Bovine Kidney cells were treated with sodium flouride, iodoacetate, and 2-deosyglucose, reagents that block glycolysis, and thus reduce phagocytosis. Sporozoites readily entered cells whose ATP stores were largely depleted. They also entered cells treated with colchicine, colcemid, and vinblastine. These latter agents did not inhibit sporozite motility after 6 hr incubation. Cytochalasin B prevented penetration of cells by inhibiting the motility of sporozoites. This effect was reversible. Warm sporozoites entered cold cells 4 times more radily than cold sporozoites into warm cells. The above findings suggest that phagocytosis is not the mechanism for entry of E. magna sporozoites into cultured cells, but that sporozoite motility is of primary importance.
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PMID:Effects of antiphagocytic agents on penetration of Eimeria magna sporozoites into cultured cells. 126 27

Effects of 5 cold storage solution on hepatic high energy phosphate metabolism and metabolic function were examined using the isolated perfused rat liver. University of Wisconsin (UW), Euro-Collins (EC), and 2 cardioplegic solutions, Bretschneider's HTK and St. Thomas Hospital solution, were studied for their protective capacity. Krebs-Henseleit bicarbonate buffer (KHB) was used to point out the effect of simple hypothermia. Liver ATP, total adenine nucleotides and energy charge losses were significantly lower during 21 h of storage in UW-preserved livers. Also, only UW-protected livers were able to complete regeneration of ATP and total adenine nucleotides after 1 h of reperfusion, whereas EC, HTK, St. Thomas and KHB stored livers only showed minimal regeneration. Concerning metabolic function, UW protected livers liberated significantly less LDH and sGOT as well in the 21-hour storage solution as into the perfusate under reperfusion conditions. This study demonstrates the capability of UW solution in liver preservation by its ability to maintain and restore high energy phosphates.
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PMID:Hepatic energy metabolism during hypothermic storage and reperfusion using different protecting solutions. 129 38

Sarcoplasmic reticulum with calcium transport activity has been isolated from the cross-striated adductor muscle of the scallop, which lives in cold (< or = 20 degrees C) sea water, by using pH 7.0 buffer solution both to homogenize the tissue and to sediment the membrane fraction. The yield of the preparation was 60-100 mg protein from 100 g of the scallop muscle. Ca(2+)-activated ATPase protein of about 100 kDa accounted for 40-50% of the protein preparation. The maximum activities of ATP-dependent, oxalate-facilitated calcium accumulation and Ca(2+)-ATPase were observed at a pH of about 7.0 and temperature of 20-30 degrees C, and their values were about 2 mumol Ca2+/mg of protein/min and about 3 mumol ATP hydrolysis/mg of protein/min, respectively. At 0 degree C, 10-20% of these activities was maintained, while at 37 degrees C, the activities were irreversibly lost. The Ca(2+)-ATPase activity was half-maximally activated at about 0.3 microM [Ca2+]. The ATPase activity exhibited non-Michaelian behavior with respect to ATP, with two different Km values of approximately 10 microM and 0.1-0.3 mM. GTP, CTP, and ITP were also hydrolyzed by the preparation at a rate of 10-30% of that of ATP. The preparation was stored at -80 degrees C with retention of function for about a year.
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PMID:Isolation and characteristics of scallop sarcoplasmic reticulum with calcium transport activity. 129 92

1. The histochemical characteristics of gastrocnemius muscle were investigated in 6-week-old cold-acclimated (5 weeks, 4 degrees C) and glucagon-treated (5 weeks, 25 degrees C, 103 nmol/kg I.P. twice daily) muscovy ducklings, two groups able to develop non-shivering thermogenesis in vivo. A comparison was made with thermoneutral controls (25 degrees C) of the same age. All animals were fed ad libitum. Fibre type, fibre area and capillary supply have been studied. Further, a quantitative histochemical method for mitochondrial Mg(2+)-ATPase activity was developed to characterize the mitochondrial coupling state in situ. 2. White gastrocnemius was composed of fast glycolytic (FG) and fast oxidative glycolytic (FOG) fibres, while red gastrocnemius contained FOG and slow oxidative (SO) fibres. In white gastrocnemius, the proportion of FG fibres was higher in glucagon-treated than in control or cold-acclimated ducklings. In red gastrocnemius, the proportion of SO fibres was higher in both cold-acclimated and glucagon-treated ducklings than in controls. The area of all fibres was generally lower in glucagon-treated than in other ducklings. 3. The capillary density was higher in both red and white components of the gastrocnemius muscle in cold-acclimated and glucagon-treated than in control ducklings, as a result of an increased number of capillaries around each fibre. 4. In all fibres, except the FG type in cold-acclimated ducklings, the staining intensity of the Mg(2+)-ATPase reaction was higher in cold-acclimated and glucagon-treated than in control ducklings whereas the staining intensity with maximal decoupling of oxidative phosphorylation by dinitrophenol was unchanged. This indicated a more loose-coupled state of mitochondria in situ in all fibres of cold-acclimated ducklings, and in FOG fibres of white gastrocnemius and SO fibres of red gastrocnemius in glucagon-treated ducklings. 5. These results indicated a higher oxidative metabolism of skeletal muscle in both cold-acclimated and glucagon-treated than in control ducklings, and for most of the parameters studied, a similarity between cold acclimation and glucagon treatment. Because of the higher loose-coupled state of muscle mitochondria in cold-acclimated and glucagon-treated than in control ducklings, the higher oxidative capacity of skeletal muscle in these ducklings could be used for heat production rather than ATP synthesis and account for muscular non-shivering thermogenesis.
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PMID:Histochemical arguments for muscular non-shivering thermogenesis in muscovy ducklings. 129 35

Even though all human respiratory cilia are similar in structure, they experience a wide range of temperatures between the initial part of the nasal fossae which behave as heat exchangers and the inferior part of the trachea, particularly when we inhale exceedingly cold or hot air. The ciliary beat frequency of ciliated cells from human nasal mucosa and from bronchial mucosa averages 8 Hz when measured at room temperature. In the present study we compared the ciliary beat frequency of human cells from nasal and tracheal mucosa brushings at different temperatures from 5 degrees C to 50 degrees C using two different techniques, ex vivo and in vitro: ex vivo in culture medium less than 24 h after sampling and in vitro after demembranation and reactivation according to a standard procedure developed in our laboratory. Measuring the ATP-reactivated ciliary beat frequency allowed us to check the thermal parameters of the dynein ATPase and all the axonemal machinery. No significant difference in frequency was observed between nasal fossae cilia and tracheal cilia when comparing extreme temperatures in both experimental procedures.
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PMID:Temperature effect on the ciliary beat frequency of human nasal and tracheal ciliated cells. 130 79

The results of a series of experiments in the cold-preserved rat liver, applying a newly developed method of pretransplant viability testing, are described. The livers were stored either under simple hypothermic conditions (KHB) or in EC, HTK, or UW preservation solution. Livers were stored up to 48 hr and reperfused after a period of hypothermic storage of 1, 7, 14, or 21 hr. In a parallel series of experiments, with livers stored under identical conditions, repeated proton relaxometry measurements (0, 1, 7, 14, 24, 32, 48 hr) were undertaken; and ATP, ADP, AMP (Atkinson's energy charge), and water content of livers, as well as pH of storage solution, were estimated. Based on a strong correlation between proton spin-spin relaxation time T2 and tissue water content (edema), this new method may be useful to estimate the amount of cell swelling during hypothermic storage from a surgical biopsy of about 200 mg within a few minutes. There was, however, no significant correlation found between energy charge and/or pH and water content, T2, or bile flow. Our method could be useful as a rapid test method in experimental cold liver storage models and may be of interest in human liver transplantation as a viability indicator in combination with other parameters.
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PMID:Cold-preserved rat liver viability testing by proton nuclear magnetic resonance relaxometry. 131 51


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