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Biomedical subjects

J Castro

Publications and source records attributed to J Castro.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1982

[Treatment of patent ductus arteriosus in preterm infants].

A retrospective study is made on the results of the treatment of 38 preterm infants with symptomatic PDA; they represented an incidence of 4% of all the admissions to our Unit from June 1978 to March 1980. 30 of the 38 infants (79%) had PDA associated with RDS. Conservative medical treatment failed in 42% of the patients, requiring the administration of indomethacin for pharmacologic closure of their PDA. The different responses to the drug in each of the established groups are commented, being the group with a birth weight less than 1,500 g who presented the highest percentage of re-openings (62.5%) and of therapeutic failures (50%). An early closure of the PDA can contribute to decrease the morbidity and mortality of these infants, specially those with lower birth weight.

Digoxin↗
PubMed1979

Orthopaedic complications of renal transplantation.

One hundred and eighty-one patients who underwent renal transplantation between 1973 and 1979 have been reviewed. Thirty of these developed one or more orthopaedic complications. The commonest and most serious was avascular necrosis of bone and the treatment of 14 patients with this condition is described. Transplant recipients who developed this complication received twice the total dose of steroids in the six months after transplantation than a control group with no avascular necrosis. The management and pathology of patients with avascular necrosis is discussed.

Adolescent↗
PubMed1975

The inotropic memory of amphibian myocardium. I.-Identification of two stimultaneous mechanisms and statement of a model.

(1) The effects of previous contractions on the actual contractile strength is studied in strips of toad ventricle. The inotropic effect is quantified by superposing a conditioning contraction to a rhythm of definite frequency, its measure being the difference in strength between a rhythm contraction in the presence and in the absence of the conditioning one. (2) The inotropic effect is studied as a function of the interval between the actual and conditioning contractions. Depressed sections of the curve, associated to shortened action potentials, are detected and excluded. (3) The inotropic effect is always positive at low frequencies, but at higher frequencies and long intervals it becomes negative. (4)In high calcium concentration the inotropic effect is always negative and does not depend on frequency. Morever, the joint effect of two previous contractions is equal to the sum of the individual effects of each one. (5) The results are interpreted in terms of two independent elementary processes, one of which potentiates whereaas the other inhibits the strength of contraction. The former disappears in high calcium. Assuming some simple properties for these processes a mathematical expression has been achieved. This expression describes the inotropic effect of any sequence of contractions as a function of intervals involved.

Action Potentials↗