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Biomedical subjects

R D Machado

Publications and source records attributed to R D Machado.

At least 37 records · Page 2Linked to original sources
PubMed1987

Evaluation of a program to overcome vitamin A and iron deficiencies in areas of poverty in Minas Gerais, Brazil.

Randon samples of children from both sexes from Belo Horizonte, the capital City, and from Turmalina, Jequitinhonha Valley, Minas Gerais, Brazil, were submitted to nutritional evaluation before and after the intervention "Program to Overcome Vitamin A and Iron Deficiencies in Areas of Poverty in Minas Gerais, Brazil". After the first examination, all the children received, with an interval of 180 days, a single oral dose of vitamin A, oral iron sulfate during 50 days, and 200 mg of Mebendazol/day for three days. Thirty days after ending administration of the third dose of medicine, the children were subjected to a new evaluation. In Belo Horizonte, the first evaluation revealed a high prevalence of deficient and low values of vitamin A in preschool children (21.5%) and school children (21.7%). A small prevalence of low hematocrit values was also observed in both groups. Deficient and low values of hemoglobin were found as well in 21.5% of preschool children and in 17.5% of school children. The second evaluation, practiced 30 days after the third dose of medicine, showed a small incidence of low vitamin A values (4.3% in preschool children and 2.9% in school children) and low hemoglobin values (6.5% in preschool children and 2.9% in school children). No deficient values of hemoglobin and vitamin A were observed. Concerning the hematocrit value, only one school child presented a low value at the second evaluation. On the other hand, in Jequitinhonha Valley, five cases of Bitot spot with conjunctival xerosis, two cases of corneal xerosis, and one case of keratomalacia were detected at the first examination. Thirty days after ending the third dose of medicine, only one corneal scar was observed. Only a small number of children with deficient and low levels of vitamin A and hemoglobin was found in the final evaluation (less than 8%), while this number was high at the first evaluation (above 38 and 12%, respectively). These results show the efficiency of the intervention Program in relation to hypovitaminosis A and iron anemia prevention. The Program is now being implemented by the Brazilian Ministry of Health.

Adolescent↗
PubMed1986

[Diagnosis of hypovitaminosis A and nutritional anemia status in the population of Vale do Jequitinhonha, Minas Gerais, Brazil].

A survey was carried out with the purpose of evaluating the nutritional status of the population of Jequitinhonha Valley in regard to vitamin A deficiency and iron-deficiency anemia. A Program--"Programa de Combate à Hipovitaminose A e à Anemia Nutricional Ferropriva em Bolsões de Probreza de Minas Gerais"--is being implanted by the Instituto Nacional de Alimentacão e Nutriçao (INAN) aiming to the prevention of such deficiencies. A random sample of 2,357 children from the towns: Turmalina, Minas Novas and Capelinha (Vale do Jequitinhonha), Minas Gerais (1,604 living in the urban and 753 in the rural areas) was submitted to an eye examination. Blood was drawn from a random subsample of these children (157 from the urban area and 107 from the rural area), in oder to detect possible nutritional problems. The following results were observed (preschool and school children, respectively): 1. Hemoglobin: 23.9% and 20% of the population in the urban area, 34.6 and 18.2% in the rural area, had low and deficient values, respectively. 2. Hematocrit: 1.5 and 2.2% of the population in the urban area, 17.3 and 5.5% in the rural area, had low values. 3. Vitamin A: 8.9 and 4.4% of the population in the urban area, 5.8 and 0% in the rural area, had deficient values (less than 10 micrograms/dl); 26.9 and 31.1% in the urban area, 26.9 and 23.6% in the rural area, had low values (10-20 micrograms/dl). These results show the occurrence of nutritional anemia and vitamin A deficiency in the observed children. As to the eye examination this was performed in 2,357 children. A high incidence of conjunctival xerosis (3.16 and 6.04% in the urban area, 7.7 and 12.6% in the rural area, in preschool and school children, respectively), was detected. Five cases of conjunctival xerosis with Bitot spot (0.2%), corneal xerosis (0.08%) and kerotomalacia (0.04%) were observed. The therapeutic effect of 200,000 UI of oral vitamin A was more efficient in preschool children (90.3% of positive reactions) than in school children (25.9% of positive reactions). The causes of the different reactions are now under study.

Anemia, Hypochromic↗
PubMed1985

Scanning electron microscopy of the electric organs of Electrophorus electricus L. II. Organs of Sachs and Hunter.

The surfaces of the organs of Sachs and Hunter of Electrophorus electricus L. were examined by scanning electron microscopy. Special attention was directed to morphological details of the electrocyte to provide a better understanding of its anterior and posterior faces. Some aspects of the microanatomy of these organs, which differ markedly from those of the main electric organ, provide new information on the structure as revealed previously by light and transmission electron microscopy. The relief, mainly expressed by papillae, is related to the actual membrane area, which is important for calculations of specific resistance and conductance. Information is also presented on the general organization of the tissue, in particular the distribution of the connective elements and external configuration of synaptic terminals. Shrinkage in preparation of tissue was evaluated and correction made whenever necessary. Correction factors for actual membrane area were calculated for anterior and posterior faces of electrocytes from both organs.

Animals↗
PubMed1984

Mitochondrial granules in Electrophorus electricus: a cytochemical approach.

The present work was performed in order to study the chemical composition of the mitochondrial granules occurring in the main and the Sachs' electric organs of Electrophorus electricus L. using cytochemical techniques. The potassium pyroantimonate technique gave positive reaction in the granules, demonstrating its calcium content. EGTA treatment of ultrathin sections, a calcium specific chelating agent, dissolved the precipitate. For detection of organic substances, the following techniques were employed: 1) the thiosemicarbazide-silver proteinate technique, showing silver proteinate precipitates in the granules, suggesting the presence of glycidic substances; 2) the zinc iodide-osmium tetroxide (ZIO) technique with marked deposition of reaction product in the granules, probably indicating the presence of lipids and/or precursor proteins; 3) with simple fixation by glutaraldehyde the granules did not show up, they were conspicuous however when OsO4 was used as a fixative, alone or after glutaraldehyde fixation; this suggests a phospholipid content; 4) the use of imidazole buffered osmium tetroxide confirmed this composition and indicates that cholesterol and phospholipids are present in the granules. The results obtained so far suggest that the mitochondrial granules of the electrocytes have a complex chemical composition that includes organic and inorganic substances, as calcium, lipids, sugar, and proteins.

Animals↗
PubMed1983

Scanning electron microscopy of the electric organs of Electrophorus electricus L. I. Main organ.

Extensive survey was made with a scanning electron microscope (SEM) of the surfaces of the main electric organ of Electrophorus electricus L. This study of the microanatomy of the electrocyte contributes to a better understanding of the relief of both anterior and posterior faces, showing peculiarities that could not be seen previously in sections either for light or for electron microscopy. The relief is evidently related to the actual membrane area, important for calculations of electrophysiological parameters. Also information on the general organization, specially the distribution of connective tissue and external configuration of synapses, is presented.

Animals↗
PubMed1982

On the cultivation of Trypanosoma cruzi in tissue cultures of the spinal and sympathetic ganglion from the chick embryo.

Trypanosoma cruzi was cultured in spinal and sympathetic ganglion cells of chick embryos. The "Y" and the "CL" strains were used for comparison, showing no differences in their tropism for the different cell types of the ganglion cultures. Nerve cells as well as satellite and Schwann cells served as host for the parasite's intracellular cycle. No toxic effect on the nerve cells was observed in heavily infected cultures. The destruction of the nerve cells is due to the multiplication of the parasites in the cell's cytoplasm. Its structure in the non parasitized nerve cells, even in direct contact with parasites, looks normal under the optical microscope and also shows no alteration in its ultrastructure.

Animals↗
PubMed1980

An electron microscopic study of the salivary gland of Rhynchosciara angelae.

The structure of the salivary gland of the dipteran insect Rhynchosciara angelae in a defined stage of the larval development, characterized by the synthesis and storage of secretion product, is described. Observations were made with both Nomarski optics and electron microscopy. Filiform projections extending into the lumen of the gland were observed in the apical portion of the cells. At the basal region junctions, characterized as hemidesmosomes, were observed between the membrane of the cell and the basal lamina. The plasma membrane presents numerous infoldings into the cell increasing considerably the surface area at this region. Throughout the cytoplasm of the gland cells numerous mitochondria, Golgi complexes, microtubules, profiles of endoplasmic reticulum, secretion granules and glycogen granules were observed. Carbohydrates were detected on ultrathin sections by using the periodic acid-silver methenamine and the periodic acid-thiosemicarbazide-silver proteinate techniques.

Animals↗
PubMed1980

Observations on the innervated face of the electrocyte of the main organ of the electric eel (Electrophorus electricus L.).

The innervated face of electrocytes in the main electric organ of Electrophorus electricus L. was examined by light microscopy, both conventional and with Nomarski contrast, and by transmission and scanning electron microscopy. Acetylcholinesterase cytochemistry was used in the demonstration of the greater density of synapses over the caudal papillae. The various techniques contributed to a better understanding of the distribution and form of papillae and synapses at the posterior face of the electrocyte. Caudal papillae are longer and thinner than those at the rostral face, but it was not possible to recognize a different type sometimes referred to in the literature as small papillae. The contact of nerve endings with the electrocyte seems to be made predominantly on the terminal half of caudal papillae, however a smaller number occur elsewhere on the posterior face. Synaptic terminals frequently appear as round profiles, but may be also elongated, with or without bulges, usually occupying a depression, and separated from the post-synaptic membrane by a space of 60-100 nm, where an expansion may be found.

Acetylcholinesterase↗