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Biomedical subjects

J Castro

Publications and source records attributed to J Castro.

At least 145 records · Page 8Linked to original sources
PubMed1987

Short and long term effects of ethanol on glycerolipid synthesis from palmitate in fasted rat hepatocytes.

Prolonged ethanol administration to rats increased the rates of glycerolipid synthesis from added [U-14C]palmitate in fasted hepatocytes; this increase was more than 2-fold in triglyceride synthesis. Prolonged ethanol administration to rats completely eliminated the acute ethanol-induced increase in triglyceride synthesis from palmitate in hepatocytes from fasted rats. This adaptive change occurred in a short initial period of about 10 days of ethanol feeding. In hepatocytes from fasted control rats, addition of ethanol produced a rapid and strong increase in the concentration of glycerol 3-phosphate. By contrast, this acute effect of ethanol disappeared in hepatocytes from fasted alcoholic rats after a prolonged--5 weeks--administration of ethanol in a liquid diet.

Alcoholism↗
PubMed1987

Increased uptake and retention of rhodamine 123 by mitochondria of old human fibroblasts.

Binding of the fluorescent dye R123 by a variety of mammalian cells has been shown to be dependent on the high transmembrane potential maintained in functional mitochondria. Recent studies in our laboratory have shown that old human fibroblasts (HF) bind and retain more R123 than young HF. In an effort to determine whether this difference in R123 uptake indeed reflected a difference in mitochondrial transmembrane potential, drugs known to disrupt the transmembrane potential of mitochondria were used to monitor the R123-mitochondria interaction of young and old HF. Distinct differences indicating that old HF maintain a higher mitochondrial transmembrane potential were observed. More significantly, perhaps this difference reflects an age-related change(s) in the structure and/or function of mitochondria.

Cell Line↗
PubMed1987

Plasma cells within the infiltrate of primary cutaneous malignant melanoma of the skin. A confirmation of its histoprognostic value.

Plasma cells within the infiltrate of primary cutaneous malignant melanoma have been reported as a valuable criterion for the prediction of lymph node metastases. In order to evaluate plasma cells, their prognostic significance and their relationship with other clinical and histological parameters, 132 cases of malignant melanoma (29 plasma cell positive and 103 plasma cell negative) were studied. The Breslow thickness, location, and ulceration were the variables related to the presence of plasma cells. The most important variables in predicting survival were lymph node involvement, clinico-pathological type, age, plasma cells, and lymphatic emboli. The most important variables for disease-free interval were lymph node involvement, plasma cells, and age.

Adolescent↗
PubMed1987

Peer perceptions of hyperactivity and medication effects.

This study focused on peer sensitivity to differences in social behaviors between hyperactive and normal comparison peers and, especially, to medication-related behavioral differences. In Study 1, normal sixth graders rated videotapes of normal and hyperactive boys playing a social interaction game. Half of the hyperactive boys were taking methylphenidate, and the other half placebo. In Study 2, fourth- and sixth-grade children rated a different sample of hyperactive boys (seen on both methylphenidate and placebo) playing the same interaction game. Hyperactive boys taking placebo were perceived as exhibiting more externalizing problem behaviors than either medicated hyperactive boys or comparison boys. The medication effects were robust, spanning many behavioral domains and emerging consistently across the 2 studies. There were few grade or gender differences. Discussion focused on children's detection of treatment-related differences in the social behaviors of their peers, as well as on the imperfect relation between social behavior and social standing.

Adolescent↗
PubMed1987

Stimulation by ethanol of triglyceride synthesis in fasted rat hepatocytes is dependent on the increase of glycerol 3-phosphate levels.

Ethanol was without effect on the incorporation of [U-14C]palmitate into triglycerides in hepatocytes from fed rats, but significantly increased triglyceride synthesis in hepatocytes from fasted rats. Glycerol alone induced a similar increase, but brought about a strong synergistic stimulation when added with ethanol. Glycerol 3-phosphate levels were also determined. It is concluded that only in the fasted state the ethanol-induced increase of glycerol 3-phosphate concentration becomes determinant for the stimulation of triglyceride synthesis from exogenous palmitate.

Animals↗
PubMed1986

Differences in glycerolipid synthesis and insulin regulation in rat hepatocytes and adipocytes.

Glycerolipid synthesis was studied by determining radioactive incorporation from either [1-14C] acetate or [U-14C] palmitate. Glycerolipid synthesis in adipocytes, mainly from exogenous palmitate, was preferentially directed to the formation of triacylglycerols, whereas in hepatocytes triacylglycerols and phospholipids were synthesized at similar rates. Insulin stimulated glycerolipid synthesis from acetate in both types of cells, being triacylglycerols more significantly increased than phospholipids. The most relevant difference was the finding that in adipocytes insulin strongly stimulated the formation of diglycerides, apparently from phosphatidate, whereas in hepatocytes insulin only slightly increased diglyceride levels. A possible role of diacylglycerol in insulin action in adipocytes, but not in hepatocytes, is also discussed.

Acetates↗
PubMed1984

Why do melanomas ulcerate?

Ulceration is an indicator of unfavourable prognosis in malignant melanoma (MM). But why do melanomas ulcerate?. Possible causes of ulceration were investigated in a group of 69 ulcerated and 69 non-ulcerated malignant melanomas. A significant correlation (P less than 0.001) between ulceration and mitotic index was found. In a group of 69 ulcerated malignant melanomas, 49 had over 7, 15 had 4-6, and only 5 had 0-3 mitotic figures per 10 high-power fields. Among 69 non-ulcerated melanomas, 28 had more than 7, 24 had 4-6, and 17 had 0-3 mitotic figures per 10 high-power fields. This study supports the hypothesis that ulceration of melanomas is usually the result of the destruction of the epidermis by the proliferating neoplastic cells or modification of blood supply due to the expansile activity of the tumor. The relationship between ulceration and mitotic activity helps clarify the prognostic significance of ulceration.

Humans↗
PubMed1984

Lipid synthesis in isolated rat hepatocytes: activation by insulin and vanadate and inhibition by ouabain.

Lipid synthesis from [1-14C] acetate was stimulated by insulin in rat hepatocytes. Vanadate also enhanced lipid synthesis, although its effect was about 2-3 times higher than that of insulin, whereas ouabain significantly decreased hepatic lipid synthesis. The stimulatory effects of both insulin and vanadate were not dependent on extracellular Ca2+. Also, this stimulation was not mimicked by either ouabain or ouabain plus vanadate, even though they are expected to induce a non-specific increase of cytoplasmic Ca2+ concentration. These results suggest that insulin and vanadate stimulation of lipid synthesis may not be mediated by changes in Ca2+ fluxes through plasma membrane.

Acetates↗
PubMed1983

Labelled lipids distribution following [3H]glycerol injection to pregnant rabbits.

1. The time dependent variation in specific activity of serum triglycerides and phospholipids has been studied following an intravenous pulse-labelling with 2-[3H]glycerol to pregnant rabbits. 2. The specific activity of triglycerides varied according to the gestation time and the maximal values of specific activity shifted to shorter times when gestation progressed to term. 3. The specific activity of serum phospholipids was higher in pregnant animals and increased with gestation time. 4. Concentrations and specific activities of both triglycerides and phospholipids were investigated in serum of pregnant and fetal rabbits at term. Concentrations of both lipid classes were notably higher in the fetal blood than in the maternal one. 5. The results were discussed on the basis of changes in hepatic biosynthesis of phosphatidic acid. Also, it was suggested a high drainage of either lipids or their degradation products by the feto-placental unit at the end of pregnancy. 6. Levels and specific activities of maternal and fetal lipids from liver and lung were also examined. The different metabolic roles of the main tissues involved in triglyceride and phospholipid metabolism were discussed.

Animals↗
PubMed1983

Dysentery caused by Balantidium coli--report of two cases.

The authors present two cases of dysentery caused by Balantidium coli with numerous colonic ulcers, documented by colonoscopy and diagnosed by endoscopic biopsies. The positive rectal exudate in one case permitted the isolation and ultrastructural study of the trophozoites. The good response to tetracyclines in the younger patient was not repeated in the older patient, who died in septic shock despite antibiotic therapy. The authors report the endoscopic findings and comment on the differential endoscopic diagnosis between parasitic and other organic colitis in view of the rarity of these examples as isolated cases in Western countries.

Aged↗
PubMed1982

[Lucio's leprosy].

A case of diffuse lepromatous leprosy with lepra reaction type II-Lucio's phenomenon-in a 24 years old male patient is reported. The histological examination of the necrotic lesions and of the apparently normal skin showed the presence of dense perivascular and perianexial lymphohystiocitic infiltrates with great quantities of bacilli. The first biopsy did not show a picture a leuccocytoclastic vasculitis but only areas of necrosis. The immunofluorescence studies revealed on direct examination complement deposits on vessel walls. The complement levels in blood were lowered and circulating inmunecomplexes were also detected. These data confirm the opinion that Lucio's phenomenon is caused by circulating inmunecomplexes fixed on dermal vessel walls causing skin necrotic lesions.

Adult↗