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Biomedical subjects

M Curto

Publications and source records attributed to M Curto.

At least 55 records · Page 3Linked to original sources
PubMed1983

[Levels of glutathione and anaerobic glycolysis in the kidney and liver of rats treated with chloroethanol].

Chloroethanol administration produces in rats a strong fall of glutathione levels in liver and kidney tissues. In liver, such a modification does not imply alterations in the levels of glucose, glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-biphosphate, lactate and pyruvate and in the glycolytic activity. In kidney, the glycolytic activity does not result modified, while it appears a reduction in levels of glucose, glucose-6-phosphate, fructose-1,6-biphosphate and triose phosphates and a remarkable increase of pyruvate. The administration of chloroethanol produces a strong fall of glutathione in the soluble and nuclear fractions of liver and in the soluble and mitochondrial fractions of kidney.

Anaerobiosis↗
PubMed1983

[Effect of insulin on brain pyruvate dehydrogenase in the rat. (Preliminary note)].

The activity of both active and total pyruvate dehydrogenase (E.C.1.2.4.1) is substantially reduced in the rat brain 24h after alloxan administration. Effects are partially removed by insulin administration. Ca++ and Mg++ produce: a) a considerable conversion of the inactive form of pyruvate dehydrogenase into its active form in a preparation from the brain of normal rats and of rats treated with insulin; b) no conversion in a preparation from the brain of rats treated with alloxan; c) some conversion in a preparation from the brain of rats treated with both alloxan and insulin. Active and total pyruvate dehydrogenase from the brain of rats treated with alloxan are activated by a preparation obtained from a mixture of entire plasma membranes-mitochondria from normal and from alloxan-treated rats, or from insulin-treated and alloxan treated rats. The oxygen uptake, the respiratory control index and the ADP/O ratio in mitochondrial preparations obtained from the brain of rats treated with alloxan show no modification at all.

Animals↗
PubMed1982

Inhibition of anaerobic glycolysis in bovine retina extracts by salicylate and acetylsalicylate.

1. Na salicylate 31 mM inhibits anaerobic glycolysis from glucose in bovine retina extracts. The formation rate of DAP and GAP increases while that of FDP, G6P, F6P and lactate decreases. All the above modifications are almost completely removed by 1.4 mM NAD+. 2. Bovine retina extracts, preincubated for 1 hr at 0 degrees C with 31 mM Na salicylate show a strongly reduced glycolytic activity. In this system G6P and F6P do accumulate, FDP, DAP, GAP and lactate decrease. These effects are not altered adding 3.5 mM NAD+ to the preincubation mixture. 3. Acetylsalicylate 31 mM inhibits anaerobic glycolysis in crude retina extracts. As the rate of lactate formation decreases, G6P and F6P do accumulate, while FDP, DAP and GAP diminish. 4. Identical modifications are observed adding the inhibitor directly to the incubation mixture, or preincubating it with the extracts at 0 degrees C for 4 hr. 3.5 mM NAD+ does not remove the effects of acetylsalicylate.

Animals↗
PubMed1982

Blood glucose and tissue glycogen concentrations in normal and deutectomised chickens during the first twelve hours after hatching.

1. Blood glucose, plasma free fatty acids and amino nitrogen, and liver, skeletal muscle, heart, brain and lung glycogen were determined in normal and deutectomised (stripped of yolk sac at hatching) chickens 45 min, 2, 4, 6, 9 or 12 h after hatching. 2. In the normal bird blood glucose decreased by 41% in the first hour after hatching, returning to the hatching value at 12 h. The free fatty acids and the amino nitrogen values did not change much during the 12-h period. Liver glycogen increased by 86% at 2 h, decreasing slightly before returning to hatching value at 12 h. 3. In the deutectomised bird blood glucose was essentially constant and almost equal, during the 12-h period, to that at hatching. Free fatty acids and amino nitrogen were lower after 1 h than at hatching and liver glycogen after 1 h declined to 50% of that at hatching, declining further with time.

Aging↗
PubMed1981

[Proline hydroxylase activity and collagen levels in the lungs of chick embryo during ontogeny].

The tropocollagen in the lungs of chicken embryos increases rapidly between the 13th and 16th day of development, then keeps constant levels and equal ones to those of the adult until the birth. The proline hydroxylase activity is highest in the lung of the embryos of 13 days old, diminishes rapidly between the 13th and 16th day, after that moderately but constantly until the birth, when it is equal to the levels found in the adult. The procollagen has a behaviour comparable to the one described for the proline hydroxylase.

Animals↗
PubMed1981

[NAD glucohydrolase from bovine retina].

The NAD glycohydrolase activity in the retina is very low compared with the one found in the brain. Therefore the retina extracts ahve a sufficiently high NAD level so that they are able to form "in vitro" lactate from glucose in anaerobiosis in presence of only ATP, Mg++ and glucose. The NAD glycohydrolase has been found in the retina in a great extent in the microsomes.

Anaerobiosis↗
PubMed1979

[Lipase and alpha amylase of chick embryo pancreas and of chickens of various ages].

In chicken embryo pancreas on the 19th day the activity of alpha-amylase and especially of lipase is very low; it increases soon after until it reaches its highest level in 36 hours old chick. Then it falls considerably on the 2nd and 10th day of normal diet; finally it starts again: in fact in three months old chickens the activity of alpha-amylase is equal to thirty-six hours old chick's, while lipase's is lower than this last one.

Age Factors↗
PubMedDate not supplied

Derangements of pyruvate dehydrogenase in circulating lymphocytes of NIDDM patients and their healthy offspring.

Pyruvate dehydrogenase (PDH) is poorly active in circulating lymphocytes of NIDDM patients; in vitro, it is unresponsive to insulin at 5 microU/ml and activated at 50 microU/ml, instead of activated and inhibited as in healthy controls. This study examines whether healthy offspring of NIDDM patients with a family history for this disease have these alterations. Twenty seven healthy offspring (23+/-10 yr, median 18 yr) and their parents (13 diabetic with a family history for NIDDM and 11 healthy without this history) were enrolled. Twenty healthy individuals without the history and matched for age and gender with the offspring served as controls. Minimum levels for enzyme activity before and after cell stimulation with insulin at 5 microU/ml were computed for a 95% CI with no more than 5% of the controls excluded. Increased or unvaried enzyme activity in response to insulin at 50 microU/ml was defined as abnormal. All NIDDM parents and 11/27 offspring had below normal enzyme activity and defective and reversed enzyme response to insulin at 5 and 50 microU/ml; three offspring had altered enzyme response to insulin at both concentrations, four to insulin at 5 microU/ml, three to insulin at 50 microU/ml and six, together with the healthy parents, had no alterations. We conclude that in healthy individuals a family history for NIDDM is frequently signaled, irrespective of age, by molecular derangements, with an apparent genetic background, in their circulating lymphocytes.

Adolescent↗
PubMedDate not supplied

Effect of sulfonylurea agents on pyruvate dehydrogenase activity in circulating lymphocytes from patients with non-insulin-dependent diabetes mellitus (NIDDM).

In circulating lymphocytes from patients with non-insulin-dependent diabetes mellitus (NIDDM) subnormal pyruvate dehydrogenase (PDH) activity returns to normal following patient treatment with sulfonylurea (gliclazide, 80 mg twice daily/5 weeks). Moreover, in vitro in cells from diabetic patients exposed to insulin at 50 microU/mL PDH activation also occurs; in cells of controls the same happens for insulin at 5 microU/mL, whereas at 50 microU/mL inhibition takes place. Therefore, the low PDH activity in cells of NIDDM patients might be caused by defective insulin control on the enzyme and its recovery in gliclazide-treated patients by drug-mediated removal of the defect. The validity of the hypothesis was verified in this study where cells of NIDDM patients before and after gliclazide treatment were exposed, in vitro, to insulin at 5 and 50 microU/mL and then tested for PDH activity. In such conditions, the profile of PDH behavior in treated patients was no longer comparable to that in untreated patients but closer to that in euglycemic controls, thus supporting the view that the recovery of PDH activity in NIDDM patients following gliclazide treatment might be the expression of an additional effect that the drug would have in these patients, aimed to renew cell responsiveness to insulin.

Diabetes Mellitus, Type 2↗
PubMedDate not supplied

Characterization of a pyruvate dehydrogenase modulator purified from insulin-treated rat brain plasma membranes.

A factor able to stimulate pyruvate dehydrogenase when added to purified mitochondria was prepared from the supernatant of brain plasma membranes incubated with physiological concentrations of insulin (25 microU/ml). The factor completely reactivated pyruvate dehydrogenase previously inhibited with ATP and was active on pyruvate dehydrogenase from brain and liver mitochondria and from peripheral lymphocytes. The insulin-dependent stimulator of pyruvate dehydrogenase was heat and acid stable, was not absorbed on charcoal and displayed an isoelectric point of 5.5. The insulin mediator was purified by gel filtration, DEAE-cellulose and sulfonated polystyrene chromatography and, after dansylation, by high performance liquid chromatography. The purified mediator displayed a molecular weight of about 2800 and appeared as a peptide rich in glycine and serine and void of proline and sulfur containing aminoacids. It retained its stimulatory action on pyruvate dehydrogenase after dansylation and was completely inactivated by trypsin and chymotrypsin. Full reactivation of ATP-inhibited pyruvate dehydrogenase was attained when mitochondria were incubated with a mediator concentration of about 0.5 microM.

Amino Acids↗
PubMedDate not supplied

Effect of insulin on the pyruvate dehydrogenase complex in the rat brain.

The level of PDHa and PDHt is substantially reduced in the rat brain 24 hours after alloxan administration. Effects are almost completely reversed by insulin administration. PDHa and PDHt from alloxan rat brains are remarkably activated when assayed on samples obtained by combining and preincubating at 30 degrees C for 30 min a homogenate from fresh unfrozen brains of alloxan rats, with a similarly treated preparation from fresh unfrozen brains of normal or insulin rats. On the contrary, no activation at all is obtained if the preincubation is carried out on homogenates from frozen and thawed brains. In alloxan rats, brain acetyl CoA level decreases remarkably whereas plasma free fatty acid concentration increases. Such changes disappear after insulin administration. The oxygen uptake, the respiratory control index and the ADP/O ratio in mitochondrial preparations obtained from brains of alloxan rats show no modifications at all.

Animals↗