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R Deana

Publications and source records attributed to R Deana.

At least 55 records · Page 3Linked to original sources
PubMed1986

Ruthenium red inhibits the mitochondrial Ca2+ uptake in intact bovine spermatozoa and increases the cytosolic Ca2+ concentration.

The uptake and cycling of Ca2+ by ejaculated bovine spermatozoa are almost completely abolished by ruthenium red, antimycin A or FCCP. The inhibitory effect of ruthenium red is also observed after washing of the dye-pretreated cells followed by addition of digitonin or filipin. In contrast, the inhibition is overcome by A23187 treatment. It is concluded that ruthenium red penetrates into intact spermatozoa, inhibits the mitochondrial Ca2+ uptake 'in situ', and causes the observed increase of the cytosolic free Ca2+ concentration.

Aminoquinolines↗
PubMed1986

Type I diabetes is characterized by insulin resistance not only with regard to glucose, but also to lipid and amino acid metabolism.

Resistance to the metabolic effects of insulin has been reported with regard to glucose disposal in type I diabetic patients (IDDM) even when they were euglycemic. Our aim was to study glucose, lipid, and amino acid metabolism during glucose clamping at multiple levels of insulin in 10 normal (N) and 6 IDDM patients. Blood glucose was maintained constant (4.7 mmol/liter) at three insulin plateaus (160 min each) [42 +/- 6 (SD) 89 +/- 11, and 1255 +/- 185 microU/ml in N and 36 +/- 4, 80 +/- 13, and 1249 +/- 107 microU/liter in IDDM]. Mean glucose disposal was 34 +/- 11, 69 +/- 10, and 84 +/- 22 mumol kg-1 min-1 in N and 16 +/- 5, 40 +/- 18, and 65 +/- 27 in IDDM, respectively. Baseline concentrations of blood lactate, pyruvate, alanine, and branched chain amino acids were 560 +/- 130, 36 +/- 9, 212 +/- 44, and 451 +/- 19 mumol/liter, in N and 793 +/- 179 (P less than 0.05), 45 +/- 14, 195 +/- 50, and 439 +/- 33 in IDDM, respectively. The maximum percent change of lactate during the euglycemic clamp was +147 +/- 23% in N and +75 +/- 15% (P less than 0.05) in IDDM; that of branched chain amino acids was -61 +/- 5% in N and -48 +/- 7% (P less than 0.01) in IDDM. Baseline concentrations of glycerol, FFA, and adipate were 44 +/- 15, 449 +/- 152, and 8 - 8 mumol/liter in N and 39 +/- 14, 473 +/- 44, and 41 +/- 14 (P less than 0.01) in IDDM. The maximum percent change of glycerol during the euglycemic clamp was -50 +/- 8% in N and -16 +/- 8% (P less than 0.01) in IDDM, that of FFA -98 +/- 3% in N and -70 +/- 4% in IDDM (P less than 0.05). No significant differences were found between N and IDDM with regard to blood concentrations of ketone bodies, citrate, ketoglutarate, and hydroxymethylglutaryl coenzyme A both before and during the euglycemic clamp. The lactate percent increase was significantly correlated to glucose disposal rate (P less than 0.001). The lactate turnover rate increased during the euglycemic clamp and was lower in IDDM than in N. We conclude that during euglycemic-multiple insulin clamp studies the greater lactate increase suggests that the flux of glycolysis is higher in N than in IDDM, tricarboxylic acid concentrations are comparable in N and IDDM, and FFA, glycerol, and branched chain amino acid decreases were less in IDDM than in N, suggesting that IDDM patients are resistant to insulin with regard to lipid and protein metabolism. The higher adipate basal values demonstrate enhanced omega-oxidation in IDDM.

Adult↗
PubMed1985

Inhibition of rat liver hydroxymethylglutaryl-CoA reductase by sulfhydryl reagents, coenzyme A esters and synthetic compounds.

The activity of the microsomal 3-hydroxy-3-methylglutaryl-coenzyme A reductase was assayed with a procedure based on the extraction of the product mevalonolactone in a benzene phase. Diamide is an uncompetitive inhibitor of the reaction, while coenzyme A disulfide and tetraethylthiouram disulfide act as non-competitive inhibitors. Diamide inhibition cooperatively increases with the inhibitor concentration. HMG produces a decrease in enzyme activity that combines with that of coenzyme A disulfide. Both CoASH and coenzyme A esters strongly inhibit the reductase activity. Three new synthetic compounds with either thio-ether or thio-ester groups also show inhibitory effect on the enzyme activity.

Acyl Coenzyme A↗
PubMed1984

Properties of a new calcium ion antagonist on cellular uptake and mitochondrial efflux of calcium ions.

Compound YS 035 [NN-bis-(3,4-dimethoxyphenethyl)-N-methylamine] is a new synthetic compound capable of inhibiting Ca2+ uptake by different cells. The inhibition of Ca2+ uptake by muscle cells isolated from chicken embryo is dose-dependent in the compound YS 035 concentration range 10-30 microM. The new compound also inhibits Ca2+ entry into rat brain synaptosomes and less effectively into baby-hamster kidney cells. Compound YS 035 partially inhibits the slow Ca2+ release induced by Ruthenium Red and the rapid Na+-dependent efflux from heart mitochondria. The inhibition of the Na+/Ca2+ exchange appears to be of a non-competitive type with an apparent Ki of 28 microM. The new Ca2+ antagonist totally inhibits the Ca2+ efflux from liver mitochondria induced by Ruthenium Red, but it does not affect the release induced by uncoupler, respiratory inhibitor or chelator, nor the mitochondrial ATP synthesis and membrane potential. The properties shown by the new compound indicate it to be a Ca2+ antagonist and a useful tool for studies on the mitochondrial Ca2+ transport.

Animals↗
PubMed1984

Calcium efflux parallel to total phosphate retention in rat liver mitochondria.

Phosphate efflux from uncoupled rat liver mitochondria was completely inhibited when mersalyl plus butylmalonate and ATP were added to a sucrose suspending medium. Despite the total retention of phosphate a calcium efflux was observed even in presence of ruthenium red. Under the above conditions no phosphate is transported in association with the ADP/ATP carrier. While mersalyl completely blocked the phosphate release induced by ruthenium red or EGTA from coupled mitochondria it only partially inhibited the CA2+-efflux. The inhibition of Ca2+ efflux was almost completely abolished in the presence of acetate. The existence of a co-transport of Ca2+ associated with phosphate is discussed.

Animals↗
PubMed1983

4-aminobutyric acid methyl ester hydrochloride, a precursor of 4-aminobutyric acid.

4-Aminobutyric methyl ester hydrochloride (GME) is able to cross the blood-brain barrier after intracardiac administration to the rat. GME has an LD50 of 1300 mg/kg in mice and 950 mg/kg in rats, exhibits an antiaggressive effect and is able to decrease isoniazid-induced convulsions in the rat. GME is hydrolyzed to 4-aminobutyric acid (GABA) by brain homogenates, acts as an inhibitor of GABA binding to crude synaptic plasma membranes, activates the release and inhibits the uptake of GABA by rat synaptosomes and acts as a competitive inhibitor of the so-called GABAse system in vitro.

Animals↗
PubMed1982

Age-dependent excretion of 3-hydroxy-3-methylglutaric acid (HMG) and ketone bodies in the urine of full-term and pre-term newborns.

Total ketone bodies and 3-hydroxy-3-methylglutaric acid (HMG) were determined in urines of full-term and pre-term newborns from the first day after birth to an age of 17. Significantly higher levels of the two catabolites were observed in the first two weeks of life of the pre-term newborns. A peak of excretion of both ketone bodies and HMG was found between the 7th and the 10th day after birth in both groups of newborns. After the 3rd month there is no significant difference between full-term and pre-term children as far as the excretion of the two analytes is concerned.

Aging↗
PubMed1982

Urinary excretion of 3-hydroxy-3-methylglutaric acid in the diabetic condition.

Urinary levels of 3-hydroxy-3-methylglutaric acid (HMG) were measured by gas-liquid chromatography (GLC) after an extraction with tetrahydrofuran in normal rats, streptozotocin-diabetic rats and starved rats. The analysis was also carried out in the urine of three diabetic patients after suspending the insulin treatment. Detectable amounts of HMG are excreted in urine by normal humans and rats and such an excretion increases in the diabetic condition. Starved rats present only traces of HMG in the urine.

Acetoacetates↗
PubMed1981

Submitochondrial localization and partial purification of the succinylCoA: 3-hydroxy-3-methylglutarate coenzyme A transferase from rat liver.

The presence and the localization of the enzyme catalyzing the transfer of a coenzyme A molecule from succinyl-CoA to 3-hydroxy-3-methylglutarate has been established in rat liver mitochondria. The enzyme was found mainly in the mitochondrial matrix but some activity was also found in the inner membrane fraction. The enzyme has been purified about 100-fold from sonically-disrupted mitochondria by high-speed centrifugation, DEAE-cellulose chromatography, (NH4)2SO4 precipitation and Sephadex G-100 filtration. The enzymatic activity was recovered in the final step as a single peak. The coenzyme A transferase appears to have a molecular weight of 42 000, the highest activity at pH 8.5 and an energy of activation of 13 kcal/mol. Mercaptoethanol increases the activity and improves its stability. The enzyme is different from the succinylCoA: 3-oxoacids coenzyme A transferase and is active also on malonylCoA. The apparent Km values obtained for succinylCoA, malnylCoA and 3-hydroxy-3-methylglutarate were 2.2 . 10(-4) M, 3.7 . 10(-4) M and 1.7 . 10(-3) M, respectively. Acetoacetate, which is the final product of the mitochondrial metabolism of hydroxy-methylglutarylCoA, showed an inhibitory effect on the enzyme activity with a Ki of 0.5 mM. The physiological role of the enzyme is discussed.

Acetoacetates↗
PubMed1981

Change of catalytic properties of erythrocyte acetylcholinesterase after binding to lecithin liposomes.

Phosphatidylcholine and phosphatidylserine + phosphatidylcholine liposomes were prepared with cholate and erythrocyte acetylcholinesterase (EC 3.1.1.7). Dipalmitoyllecithin- and egg lecithin-acetylcholinesterase complexes exhibit an affinity for acetylthiocholine different from that of the free enzyme. The binding to lecithin apparently abolishes the excess substrate inhibition of acetylcholinesterase; the affinity constants of acetylthiocholine, acetylcholine and acetylcarnitine for the lecithin-bound enzymes are higher than the ones found for the free enzyme. Binding to lecithin decrease the optimum pH value for acetylcholinesterase, increase the resistance of the enzyme to heat denaturation and reduces the extent of activation by Ca2+.

Acetylcarnitine↗
PubMed1979

Inhibition of rat liver mitochondrial 3-hydroxy-3-methylglutaryl-CoA lyase by succinyl-CoA.

1. Succinyl-CoA inhibits 3-hydroxy-3-methyl-glutaryl-CoA lyase (EC 4.1.3.4) when added to purified preparations of the enzyme. 2. The apparent Ki value is 2.1 x 10(-4) mol/l and the inhibition has the features of a partially competitive inhibition. 3. The effect of succinyl-CoA both added and enzymically produced on the lyase activity of sonically disrupted rat liver mitochondria results in decreased acetoacetate formation. 4. This occurs with mitochondria obtained from normal, starved and streptozotocin-diabetic rats.

Acyl Coenzyme A↗
PubMed1977

Levels of neurotransmitters in brain of vitamin B12 deficient rats.

The levels of norepinephrine, dopamine and 5-hydroxytryptamine in brain homogenates of vitamin B12-deficient rats have been investigated. The norepinephrine levels were significantly decreased in the deficient animals compared to controls. The two major catabolic pathways of norepinephrine e.g. monoamine oxidase and catechol-O-methyl transferase did not show significant variations. Both acetyl cholinesterase and butiryl-cholinesterase markedly decreased in the plasma of the vitamin B12-deficient rats.

Acetylcholinesterase↗
PubMed1975

Changes relevant to catecholamine metabolism in liver and brain of ascorbic acid deficient guinea-pigs.

A chronic deficiency of ascorbic acid was induced in guinea pig. The level of catecholamines, copper and the activities of ceruplasmin, catecholamine oxidase, monoamineoxidase and acetylcholinesterase were checked in brain, liver and serum. Also the levels of ascorbic acid and glutathione were measured in the organs of ascorbic acid-deficient animals. The most important changes due to the ascorbic acid deficiency were observed in the brain were monoamineoxidase, catecholamineoxidase, acetylcholinesterase and the concentration of catecholamines were altered. The statement that brain is the organ most affected by the ascorbic acid deficiency is discussed.

Acetylcholinesterase↗
PubMed1975

A biochemical study of vitamin B12 deficiency in the baboon.

A dietary deficiency of vitamin B12 was produced in the baboon by use of an artificial diet. Deficiency was further aggravated by feeding propionate or ampicillin, as judged by serum, liver and brain vitamin B12 levels, and urinary excretion of methyl malonic acid. Reduced glutathione levels in the blood and liver increased during deficiency, while ascorbic acid levels were not affected, Brain and liver nucleic acids did not change significantly. Blood pyruvate and serum lipid factors were affected more in the group fed propionate. These results are compared with the work on vitamin B12 deficient rats and pernicious anaemia in humans.

Ampicillin↗