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Biomedical subjects

A Valenzuela

Publications and source records attributed to A Valenzuela.

At least 91 records · Page 5Linked to original sources
PubMed1989

Effect of silybin dihemisuccinate on the ethanol metabolizing systems of the rat liver.

Silybin dihemisuccinate produces a decrease in the ethanol metabolic rate of rats. This effect is ascribed to an inhibition of the microsomal ethanol oxidizing system (MEOS). Alcohol dehydrogenase activity, catalase activity and NADPH cytochrome c reductase activity are not affected by the flavonoid. It is proposed that the inhibition of MEOS by silybin dihemisuccinate is related to its antioxidant properties, acting as a scavenger of the free radicals involved in ethanol metabolism by this enzymatic system. This observation may have therapeutical implications because microsomal lipid peroxidation induced by hydroxyl free radicals has been related to the etiology of hepatic alcoholic disease.

Animals↗
PubMed1989

Effects of pindolol and propranolol on blood lipids in hypertensive patients.

Since beta-blockers could affect lipid levels at the therapeutic dose range in hypertensive patients, a parallel 6-month randomized trial with pindolol (PDL) (16 pts.) and propranolol (PPL) (23 pts.) was designed (mean age = 55 + 7.1 years and 57 + 8.0 years; 9 males, 7 females and 15 males, 8 females, respectively). Total cholesterol, LDL and HDL fractions, and triglycerides (TGs) were determined before (washout phase) and during 1, 3, and 6 months of therapy. Patients were instructed to maintain their usual dietary habits. Daily drug doses were adjusted step by step to attain an optimal hypotensive effect (PDL 15-45 mg, PPL 180-240 mg). In the PPL-treated group, total cholesterol and LDL did not change significantly, HDL decreased (from 45.2 to 40.5 mg/dl, p less than 0.05) and TG increased (from 133 to 169 mg/dl, p less than 0.05). In the PDL group total cholesterol and LDL did not change either, but HDL increased (35.9 to 44.7 mg/dl, p less than 0.01) and TGs, were reduced (from 169 to 131 mg/dl, p less than 0.05). No dose-effect relationship was recorded. It is concluded that pindolol does not negatively influence HDL nor the TG blood lipid profile as does PPL. Accordingly, pindolol might be preferred to propranolol in the treatment of hypertensive patients with an unfavorable lipid profile, but this assumption remains to be proven in larger, prospective, long-term followup trials.

Aged↗
PubMed1989

Ingestion of high doses of fish oil increases the susceptibility of cellular membranes to the induction of oxidative stress.

Feeding rats with 4 g/kg body weight of sardine oil during 7 or 14 days increases the content of eicosapentaenoic acid and docosahexaenoic acid in the erythrocyte and hepatic microsomal membranes by 2 to 6%. These membranes show increased susceptibility to the induction of oxidative stress, expressed as lipid peroxidation, when they are exposed to Fe2+-ascorbate and to NADPH-FE3+-ADP, respectively. The results indicate that in order to prevent the increased susceptibility to lipid peroxidation, supplementation with larger amounts of antioxidants may be needed than those required to stabilize the oil.

Animals↗
PubMed1989

Silybin dihemisuccinate protects against glutathione depletion and lipid peroxidation induced by acetaminophen on rat liver.

Acetaminophen hepatotoxicity is characterized by glutathione depletion, cellular necrosis, and, in some instances, by the induction of lipid peroxidation. Silybin dihemisuccinate, a soluble form of the flavonoid silymarin, protects rats against liver glutathione depletion and lipid peroxidation induced by acute acetaminophen intoxication. Other biochemical parameters such as serum transaminases did not show the drastic increase observed under acetaminophen intoxication when animals were treated with the flavonoid. Preliminary results suggest that silybin dihemisuccinate may be another antidote against acetaminophen hepatotoxicity.

Acetaminophen↗
PubMed1989

Selectivity of silymarin on the increase of the glutathione content in different tissues of the rat.

Silymarin, a flavonoid extracted from the seeds of the milk thistle, Silybum marianum, increases the redox state and the total glutathione content of the liver, intestine, and stomach of the rat. The same treatment does not affect the levels of the tripeptides in the kidney, lung, and spleen. This selective effect of the flavonoid on the digestive organs is ascribed to its pharmacokinetics on the digestive track, where the biliary concentration of silymarin is increased and maintained via the entero-hepatic circulation.

Animals↗
PubMed1989

[Biologic and physiologic role of taurine and its derivates].

Taurine is ubiquitous in nature but its distribution and amount differs among biological organisms. Its role as an antioxidant and osmoregulator has been recently recognized. Synthesis and transport of taurine may be different among species with implications on the role of taurine in normal physiologic processes and pathologic conditions.

Animals↗
PubMed1989

Morphological diagnosis of sudden cardiac death.

The study reveals preliminary results of a bilateral project involving the Institute of Forensic Medicine, University of Copenhagen (Denmark) and the Institute of Legal Medicine, University of Granada (Spain). Morphological findings were compared to the results of thanatochemical analyses of pericardial fluid and myocardium in the same cases of sudden death of cardiac origin. Fifty cases were included, and the results of the macroscopic, histochemical, histological and cytological examinations revealed that the NBT test and microscopy are valuable methods in diagnosing infarctions, while cytological examination of pericardial fluid seems to be of no value.

Accidents, Traffic↗
PubMed1989

[Active forms of oxygen, oxidative stress and its pathologic significance].

Chemically hyperactive forms of oxygen can induce a variety of functional and morphologic alterations in aerobic organisms. Defensive mechanisms against oxidative damage may be involved in the etiology of pathologic processes induced by oxidative stress. Different antioxidant substances are used in treatment of these conditions.

Humans↗
PubMed1989

Effects of lead acetate on cerebral glutathione peroxidase and catalase in the suckling rat.

Exposure of immature rats to lead acetate results in hemorrhagic encephalopathy of variable evolution. As the maintenance of adequate protection against peroxides may be critical in this condition, the activities of selenium-glutathione peroxidase and catalase in cerebrum and cerebellum of suckling rats poisoned with lead acetate were studied from day six to day sixteen post-exposure. Age-related decreases of glutathione peroxidase and catalase activities in both controls and lead poisoned animals were observed. An increase in catalase activity was observed in cerebrum and cerebellum of lead-treated rats compared to controls. Glutathione peroxidase activity did not change significantly in cerebrum over the period studied. By contrast, glutathione peroxidase activity in cerebellum of lead-treated rats remained at about twice the control level over most of the study period. This apparent increase in glutathione peroxidase activity may be due either to a slower ontogenic decrease of its specific activity or to enzyme induction in response to oxidant stress in cerebellum.

Animals↗
PubMed1988

Postmortem diagnosis of diabetes mellitus. Quantitation of fructosamine and glycated hemoglobin.

Fructosamine and glycated hemoglobin were determined in samples from 52 cadavers autopsied in the Forensic Pathology Institute of the University of Copenhagen (Denmark). The population studied comprised 15 adult subjects with history of diabetes mellitus and 37 adult non-diabetic subjects. The fructosamine/total protein ratio was 1.7 times higher in diabetic than in non-diabetic subjects, as was the case for glycated hemoglobin. Measurement of glycated serum protein appears to be a useful tool for the postmortem diagnosis of fatal diabetic coma and glucose concentration before death.

Adult↗
PubMed1988

Riboflavin status and photo-induced riboflavin binding to the proteins of the rat ocular lens.

The presence of radioactivity in lenses of rats injected intraperitoneally with a solution of tryptophan and 14C-riboflavin, irradiated during 48 hours and under N2 atmosphere, was detected. The excitation fluorescence spectrum (lambda emission = 520 nm) of the soluble lens fraction corresponds to the riboflavin decomposition product of lumichrome type. When 14C-riboflavin enriched lenses were exposed to visible light, a photo-induced binding between riboflavin and a water insoluble protein fraction of the lenses was observed. This finding may help to clarify the lens modifications during aging and in cataractogenesis.

Animals↗
PubMed1987

Age-dependent changes in rat liver lipid peroxidation and glutathione content induced by acute ethanol ingestion.

The study of the influence of the age of animals (13 to 53 weeks) on total liver thiobarbituric acid reactive substances (TBAR) content showed an increase which is maximal in rats of 39 weeks of age compared to young animals (13 weeks), followed by a dimunition in the 53 weeks old group. In this situation, the content of hepatic GSH and total GSH equivalents as well as the GSH/GSSG ratio were decreased with ageing, while GSSG levels were enhanced in the oldest group studied. Acute ethanol intoxication resulted in a marked increase in liver TBAR content in young animals, together with a decline in GSH, total GSH equivalents and GSH/GSSG ratio, and an enhancement in GSSG. These changes elicited by ethanol intake were reduced with ageing. It is concluded that ethanol-induced oxidative stress in the liver is diminished during ageing, despite the progressive decrease in the glutathione content of the tissue observed in control animals.

Aging↗