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L C Silva

Publications and source records attributed to L C Silva.

54 records · Page 3Linked to original sources
PubMed1993

[Characteristics of the introduction of foods into the diets of infants in Cuba].

The purpose of this study was to examine the prevailing pattern of introduction of nonmilk foods into the diets of children in Cuba and to assess the degree to which this pattern deviates from internationally accepted recommendations. A cross-sectional study was carried out using a simple random sample of 6,688 children under 1 year of age from all over Cuba. The data were analyzed through logistic regression. The study was carried out in 1990 using the pyramidal structure of the national public health system for the collection of data. Through the status quo method, information was obtained on consumption of four representative foods--juice, vegetables, meat, and fish--and some data were gathered on the child. Consumption prevalence rates were estimated at the beginning and the end of the age ranges (in days) that WHO considers optimum for the introduction of these foods. A marked divergence was found between recommended and actual practice. The recommendations were followed in 3% of the cases for juice, 9% for vegetables, 4% for meat, and 25% for fish. It is noteworthy that noncompliance with the recommendations basically takes the form of early introduction of these foods. The exception is vegetables, which are introduced considerably later than recommended, a fact that seems to reflect a cultural distaste for this food.

Cross-Sectional Studies↗
PubMed1992

Proteoglycans synthesized by the hepatic granulomas isolated from schistosome-infected mice and by the granuloma-derived connective tissue cell lines.

Proteoglycans synthesized in vitro by periovular granulomas isolated from livers of schistosome-infected mice were compared with those produced by granuloma-derived cell lines: the primary cell line GR and the permanent cell line GRX. Proteoglycans were metabolically labelled with 35S-sulfate and extracted with 4 M guanidine-HCl containing 2.0% Triton X-100, in the presence of proteinase inhibitors. The radiolabelled proteoglycans were purified and characterized by anion-exchange, gel-filtration and affinity-column chromatography. Heparan sulfate proteoglycans (HS-PGs) and chondroitin sulfate/dermatan sulfate-containing proteoglycans (CS/DS-PGs) were detected in both the culture medium and the cell-associated fractions obtained from GR cells. More than 90% of the cell-associated HS-PG from these cells contained a hydrophobic portion, as evidenced by their ability to bind to octyl-Sepharose. In contrast, among the secreted proteoglycans, it was the CS/DS-PG and not the HS-PG that bound to this resin. The major fractions of cell-associated and secreted proteoglycans from GRX cells were HS-PGs. Similar to HS-PGs from GR cells, 50% of the cell-associated HS-PG bound to octyl-Sepharose, while only 20% of secreted proteoglycans (HS-PGs) bound to this resin. The proteoglycans purified from the whole granuloma were composed mainly of DS-PG, of a size and hydrophobicity similar to the CS/DS-PG from GR cells. Possible correlations among the structure, secretion, distribution and function of proteoglycans in granulomatous reactions are discussed.

Animals↗
PubMed1992

Membrane-associated and secreted proteoglycans from a continuous cell line derived from fibrotic schistosomal granulomas.

Proteoglycans were isolated from a continuous murine cell line (GRX) established from fibrotic granulomas induced in mouse liver by schistosomal infection, representative of liver connective tissue cells. The proteoglycans were labelled with 35SO4, extracted by guanidine-HCl + Triton X-100 in the presence of proteinase inhibitors, and purified by anion-exchange, gel-filtration and affinity-column chromatography. The major fractions of cell-associated and secreted proteoglycans are heparan sulfate proteoglycans. Gel-filtration chromatography on Sephacryl S-400 revealed Kav values of 0.20 and 0.30 for the cell-associated and secreted heparan sulfate proteoglycans, respectively. About 50% of the cell-associated heparan sulfate proteoglycans contained hydrophobic regions, as evidenced by their ability to bind to octyl-Sepharose, while only about 20% of secreted proteoglycans bound to this resin. In addition, no proteoglycan was competitively displaced from the cell surface by heparin. Taken together with other reports on proteoglycan synthesis by a variety of cell types in culture, these observations suggest that cell-surface heparan sulfate proteoglycans possibly contain a hydrophobic domain that functions as a membrane anchor in their attachment to cells. Addition of beta-D-xyloside to the cultures greatly enhanced the release of 35S-dermatan sulfate to the medium. Interestingly, dermatan sulfate is the major glycosaminoglycan found in the schistosoma-induced granuloma, from which the GRX cell line is derived. These studies provide the first biochemical description of the proteoglycans produced by a liver connective tissue cell line derived from schistosomal granulomas.

Animals↗
PubMed1992

Seroepidemiology of schistosomiasis mansoni.

In population surveys in which the Schistosoma mansoni intensity of infection is low, or in localities where the schistosomiasis control program had success, the parasitologic methods lack in sensitivity. Despite of some limitations, the immunological methods are useful to provide valuable information in such field conditions. Thus, the prevalence of schistosomiasis in untreated population can be determined by the detection of IgG or IgM antibodies, as well as the incidence by the IgA antibodies, employing mainly immunofluorescence (IF) and immunoenzymatic (ELISA), and in some extent hemagglutination (HA) or even skin test. The true prevalence and incidence of schistosomiasis can be estimated using a probabilistic model equation, since knowing before-hand the sensitivity and specificity of employed test. The sensitivity and the specificity of serologic test become higher in low aged group, under 14. The geometric mean IF titers also gives a positive correlation with the intensity of infection. Presently, there are need of serologic tests which are economic and practical in seroepidemiologic inquiries, requiring no specialized personnel to collect population blood or serum samples, and also easily interpret the test results. The reagents for such tests are desired to be stable and reproducible. Moreover, it is expected that the tests can distinguish an active infection.

Adolescent↗
PubMed1990

Identification of cells responsible for synthesis of sulphated glycosaminoglycans in schistosome-induced hepatic granulomas.

Sulphated glycosaminoglycans were isolated from schistosome-induced hepatic granuloma and from the pericellular, intracellular and extracellular compartments of two murine cell lines derived from granulomas: the primary cell line GR, and the permanent cell line GRX, established spontaneously from GR. The glycosaminoglycans composition in the whole granuloma was similar to that observed in the intracellular and extracellular compartments of GR cells. This result suggests that GR cells may be the major cell population involved in the synthesis and accumulation of glycosaminoglycans in the granulomas, and play an important role in the process of hepatic fibrosis. The conversion of the primary cell line GR into the established GRX cells did not modify the ratios that prevail among different glycosaminoglycans of the cell surface. However, it decreased the synthesis and secretion of glycosaminoglycans, reduced the proportion of iduronic acid units in the chondroitin sulphate, and increased the proportion of heparan sulphate in intracellular and extracellular pools. These characteristics of the GRX cells are similar to those observed in long-term cultures of smooth-muscle cells. In agreement with the general phenomenon of progressive de-differentiation during in-vitro culture of primary cell lines, these data indicate that the connective tissue cells of liver may belong to the myofibroblastic cell lineage.

Animals↗
PubMedDate not supplied

[The Bayesian approach: another way of drawing inferences].

The serious objections made with regard to significance tests account for the necessity of employing another inferential procedure. Bayesian methods are free of such objections, and they provide a very attractive alternative. By means of a simple example, this article illustrates how a typical problem of medical research could be solved using these two approaches. Bayesian methods offer more information and are more useful than conventional ones for analyzing experimental outcomes. In addition, a natural interpretation of conclusions are given by Bayesian methods. Finally, modern computational programs allow us to solve their complex calculation.

Bayes Theorem↗