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Biomedical subjects

R Gomez

Publications and source records attributed to R Gomez.

At least 163 records · Page 9Linked to original sources
PubMed1991

Carotenoid composition in the cyanobacterium Phormidium laminosum. Effect of nitrogen starvation.

When pigments of the non-N2-fixing cyanobacterium Phormidium laminosum were carefully extracted and analyzed in a completely O2-free atmosphere, by either high performance liquid chromatography (HPLC) or thin layer chromatography (TLC), the presence of only two carotenoids (namely, beta-carotene and nostoxanthin) was detected. However, exposure of pigments to an air atmosphere during their manipulation led to the rapid appearance in the organic extracts of at least three additional carotenoids (identified as caloxanthin, zeaxanthin and beta-cryptoxanthin). This fact could explain the presence in cyanobacteria of such hydroxylated derivatives of beta-carotene widely reported in the literature. Nitrogen starvation also resulted in an important decrease on the relative beta-carotene/nostoxanthin content of cells, suggesting that this nutritional condition affects thylakoid membranes more drastically than cytoplasmic membranes.

Carotenoids↗
PubMed1990

Effect of 1,25(OH)2D3 and 24,25(OH)2D3 on calcium ion fluxes in costochondral chondrocyte cultures.

Vitamin D3 metabolites have been shown to affect proliferation, differentiation, and maturation of cartilage cells. Previous studies have shown that growth zone chondrocytes respond primarily to 1,25(OH)2D3 whereas resting zone chondrocytes respond primarily to 24,25(OH)2D3. To examine the role of calcium in the mechanism of hormone action, this study examined the effects of the Ca ionophore A23187, 1,25(OH)2D3, and 24,25(OH)2D3 on Ca influx and efflux in growth zone chondrocytes and resting zone chondrocytes derived from the costochondral junction of 125 g rats. Influx was measured as incorporation of 45Ca. Efflux was measured as release of 45Ca from prelabeled cultures into fresh media. The pattern of 45Ca influx in unstimulated (control) cells over the incubation period was different in the two chondrocyte populations, whereas the pattern of efflux was comparable. A23187 induced a rapid influx of 45Ca in both types of chondrocytes which peaked by 3 minutes and was over by 6 minutes. Influx was greatest in the growth zone chondrocytes. Addition of 10(-8)-10(-9) M 1,25(OH)2D3 to growth zone chondrocyte cultures results in a dose-dependent increase in 45Ca influx after 15 minutes. Efflux was stimulated by these concentrations of hormone throughout the incubation period. Addition of 10(-6)-10(-7) M 24,25(OH)2D3 to resting zone chondrocytes resulted in an inhibition in ion efflux between 1 and 6 minutes, with no effect on influx during this period. Efflux returned to control values between 6 and 15 minutes. 45Ca influx was inhibited by these concentrations of hormone from 15 to 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Aortopulmonary window with anomalous origin of the right coronary artery from the pulmonary trunk.

A case of aortopulmonary window associated with an anomalous origin of the right coronary artery from the pulmonary artery in a 3-month-old boy is reported. Angiographic diagnosis could be difficult because of the simultaneous filling of both great arteries that obscure the origin of the anomalous vessel; however, a careful evaluation of the angiogram may contribute to an accurate diagnosis. The surgical correction of this association of defects requires the connection of the aorta with the anomalous coronary ostium. An intrapulmonary tunneling procedure by means of a baffle is described.

Journal Article↗
PubMed1983

Demographic and nondemographic characteristics of psychiatric emergency patients.

The demographic variables of age, sex, marital status, socioeconomic status, race, and diagnosis of psychiatric emergency patients have been reviewed as to their possible effects on disposition. In addition, certain nondemographic factors have also been discussed. Both adult and pediatric psychiatric emergencies were considered.

Adolescent↗
PubMed1982

The membrane phenotype of T-prolymphocytic leukaemia.

Cells from 13 cases of T-prolymphocytic leukaemia (T-PLL) were studied with a battery of immunological techniques in order to define their membrane phenotype. All cases were E-rosette positive and were negative with OKT6, anti-HLA-DR, anti-Ig and M-rosettes; in 3, 20-30% of the cells had receptors for C3b. 7 cases had predominantly a 'helper/inducer' T-subset phenotype, (OKT4+, OKT8-) and 4 had a 'suppressor/cytotoxic' phenotype (OKT8+, OKT4-). Cells in 2 cases coexpressed OKT4 and OKT8 in 48% and 95% of prolymphocytes and in another, both OKT4 and OKT8 were negative. Terminal transferase (TdT) was negative by IF in all the cases, but a low positive level was detected biochemically in one. Although T-PLL appears to be heterogenous in respect of membrane phenotype, the observation of unexpected features in 8 of the cases raises the possibility that it may originate in a cell of intermediate maturation between late thymocytes and mature T-lymphocytes. These features plus the clinical manifestation of the disease - typical morphology, splenomegaly, lymphadenopathy, skin lesions, high WBC and aggressive clinical course - help define T-PLL as a distinct clinicopathological entity.

Aged↗
PubMed1981

Unusual T-cell phenotype in advanced B-chronic lymphocytic leukaemia.

T-lymphocytes isolated by E-rosetting from 22 patients with B-cell chronic lymphocytic leukaemia (B-CLL) showed membrane phenotype features distinct from those of normal T-lymphocytes. These changes were particularly marked in advanced disease (Rai stages II, III, IV and WBC over 100x10(9)/l). The most significant finding was the demonstration, in 10 cases, of a major population of E-rosette positive cells (40-80%) unreactive with the OKT monoclonal antibodies against mature or immature T-cells; 15-30% of the cells were unreactive in seven other cases. A significant reduction in OKT4 positive (helper) lymphocytes was seen in 18 cases. The proportion of OKT8 positive cells was increased in two and normal or low in the rest. Only four patients with early disease (stages 0 and I) had a normal T-cell phenotype. These findings could explain abnormalities previously described in the T-lymphocytes of B-CLL and provide new insights into the pathogenesis of the disease.

Antibodies, Monoclonal↗