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Biomedical subjects

M F Costa

Publications and source records attributed to M F Costa.

13 recordsLinked to original sources
PubMed1992

Relationships between titers of antibodies immunoreacting against glycolipid antigens from Mycobacterium leprae and M. tuberculosis, the Mitsuda and Mantoux reactions, and bacteriological loads: implications in the pathogenesis, epidemiology and serodiagnosis of leprosy and tuberculosis.

Analysis of cell-mediated immunity [(CMI) as judged from the Mantoux, Fernandez, and Mitsuda reactions and the presence of granulomas in biopsy material] against humoral immunity (measurements of anti-PGL-I, PGL-Tb1, and SL-IV IgG and IgM antibody titers by ELISA) were performed in selected human populations. The investigations yielded data indicating that humoral (B-cell) responses preceded protective CMI in both tuberculosis and leprosy. The B-cell responses were unrelated to (unfavorable) cell-mediated delayed-type hypersensitivity (DTH). Notwithstanding the difficulty in inferring sequential events from studies in humans, it was shown that in humoral responses there was an initial rise of specific IgM immunoglobulins that switched afterward to IgG production during subclinical tuberculosis and leprosy infections. In patent tuberculosis disease the IgM-to-IgG switch was observed in the majority of patients; in patent leprosy disease the switch was impaired in the majority of patients. The clinical, immunological, and laboratory data indicated that the B-cell responses were suppressed as protective CMI was re-established in the patients during the protracted subclinical infection. According to the data, the diagnosis of subclinical tuberculosis and leprosy may be accomplished using ELISA. The yearly risk of tuberculosis in apparently healthy persons but with significant antibody titers was estimated at 44%; the yearly risk for leprosy has not yet been established. The clinical, epidemiologic, and diagnostic implications of these findings are discussed.

Antibodies, Bacterial↗
PubMed1985

Further characterization of [3H] flunitrazepam binding sites on cultured mouse astroglia.

Astroglial cells in primary cultures bind [3H]flunitrazepam with a high affinity on a single type of site and on a number of binding sites which increased during astroglial growth and differentiation. These binding sites show a particular pharmacological spectrum characterized by an inhibition of high affinity by RO-5-4864 (4'-chlorodiazepam), an anticonvulsant of the benzodiazepine family and by an inhibition of binding of lower affinities by diazepam clonazepam and clobazam. RO-5-4864 and clonazepam compete for the same binding site in astroglia. The heat stability and the hormonal modulation by thyroxine are similar for astroglia and neuronal-cells. Benzodiazepines modulate the astroglial 5-HT receptor. Such an effect could be a possible physiological response to benzodiazepines for astroglial cells in primary cultures.

Animals↗
PubMed1982

Uptake and binding of serotonin by primary cultures of mouse astrocytes.

Primary cultures of glia contain a high glial fibrillary acidic protein level and exhibit important glutamine synthetase activity. They take up serotonin via a high affinity carrier-mediated system with a Km of micromolar range. The Km of this transport process does not vary during cell growth or maturation; however, during the last period of morphological change induced by dibutyryl cyclic AMP, an increase in Vmax is observed. Chlorimipramine, fluoxetine and fenfluramine at 10-4 M inhibit this uptake. 3H-5-HT still binds to partially purified astrocytic membranes on a single type of site. During growth, neither KD nor Bmax were modified. During the maturation period, KD decreased to about 50% of its control level. Methysergide inhibits that binding.

Animals↗
PubMed1982

Partial characterization of temperature-sensitive mutants of foot-and-mouth disease virus, O1 caseros strain.

The preliminary characterization of four temperature-sensitive (ts) mutants of the O1 Caseros strain of foot-and-mouth disease virus is described. Two mutants, ts 6 and ts 40, showed a very low RNA synthesis rate at nonpermissive temperature and were classified phenotypically as RNA(-). Shift-up experiments demonstrated an incapacity to organize the RNA replicative process at nonpermissive temperature. Another mutant (ts 139) behaved phenotypically as RNA(+) and its virions were more thermolabile than the wild type virus, so the defect in this mutant is likely to be in one of its structural proteins. Finally, mutant ts 5 was phenotypically RNA(+); its leak production at nonpermissive temperature was high, and the shift-up experiment showed a defect that was expressed either late in the replicative cycle or continuously.

Animals↗
PubMed1981

Benzodiazepine receptors on primary cultures of mouse astrocytes.

Benzodiazepines bind to glial membranes on a single type of site, with a high affinity (KD = 5 x 10(-9) M) on about 100 fmol of sites per mg protein. The number of binding sites is increased when the membranes are treated with Triton X-100. Antiepileptic drugs such as clonazepam and phenobarbital and hypnotic drugs such as Ro-11-3128 and Ro-11-6896 are able in pharmacological concentrations to displace [3H]flunitrazepam from its glial binding sites.

Animals↗
PubMedDate not supplied

Exposure to acellular blood products and risk of HIV infection in hemophiliacs from Belo Horizonte, Brazil.

Results of a HIV prevalence study conducted in hemophiliacs from Belo Horizonte, Brazil are presented. History of exposure to acellular blood components was determined for the five year period prior to entry in the study, which occurred during 1986 and 1987. Patients with coagulations disorders (hemophilia A = 132, hemophilia B = 16 and coagulation disorders other than hemophilia = 16) were transfused with liquid cryoprecipitate, locally produced, lyophilized cryoprecipitate, imported from São Paulo (Brazil) and factor VIII and IX, imported from Rio de Janeiro (Brazil), Europe, and United States. Thirty six (22%) tested HIV seropositive. The univariate and multivariate analysis (logistic model) demonstrated that the risk of HIV infection during the study period was associated with the total units of acellular blood components transfused. In addition, the proportional contribution of the individual components to the total acellular units transfused, namely a increase in factor VIII/IX and lyophilized cryoprecipitate proportions, were found to be associated with HIV seropositivity. This analysis suggest that not only the total amount of units was an important determinant of HIV infection, but that the risk was also associated with the specific component of blood transfused.

Adolescent↗
PubMedDate not supplied

Clinical repercussion of the various states of extrinsic pulmonary granulomatoses on the bronchial tree.

The AA. evaluated the importance of the bronchial participation in 175 patients with histologically confirmed pulmonary granulomatoses. Many had symptoms specifically due to bronchial changes. In some of the patients, bronchial symptoms appeared late in the natural development of the disease, while in others they filled the clinical picture from the beginning. The AA. discuss the possible influence of other aggressors of the bronchial mucosa, e.g. tobacco, and conclude that, in a fair number of cases, it was not possible to attribute the pathology to them. In a patient with a history suggestive of pathology due to inhaled foreign particles, even when bronchial symptoms predominate, an extrinsic pulmonary granulomatosis must be considered for diagnosis.

Bronchi↗
PubMedDate not supplied

The role of bronchoscopy in the study of extrinsic pulmonary granulomatoses.

As the bronchial mucous membrane is one of the chief barriers against aggression to the respiratory tract by inhaled particles, the AA. reviewed 68 patients with pulmonary granulomatoses studied at the Department of Chest Diseases, Lisbon University Hospital, that had been submitted to bronchoscopy. Only about 22% of these had normal appearing mucosa, while the rest, among other aspects, showed congestion and edema. Bronchial biopsies were taken in the majority of patients (44). Only in two cases was the mucosa considered histologically normal while granulomas were found in 36% and generally it was possible to identify the nature of the foreign particles inhaled. Analysing the results, the AA. conclude that organic particles seem to produce granulomatous reactions more frequently, while inorganic particles seem rather to produce a marked irritating effect. The frequency with which bronchial changes were found in these patients seems to warrant the conclusions that bronchoscopy plays an important role in the study of patients with extrinsic pulmonary granulomatoses.

Adolescent↗