Biomedical subjects
Publications and source records attributed to M Ravaoarinoro.
Rotavirus were detected by enzyme immuno assay method in 36 p. 100 of faecal specimens from 80 children with acute diarrhoea and in 8 p. 100 of 80 controls, over a period of three months in Majunga area. The incidence of rotavirus was studied according to age group, sex, nutritional status, and clinical aspects.
A total of 170 sera from a population of malagasy women aged from 15 to 35 year old were assayed in complement fixing test for CMV-antibodies. 80 p. 100 were found positive. Positive cases have been studied according age groups, matrimonial status, number of gestation.
A total of 80 nasopharyngeal secretions collected from malagasy children (53 boys and 27 girls) with viral acute respiratory infection, aged from 6 days to 10 year old admitted to the Pediatric Department of Antananarivo General Hospital from may to July 1983, were investigated by indirect immunofluorescence method. 54--samples were found positive for respiratory viruses. Distribution according age groups and sex has been studied: children belonging to 25-36 month age group and male sex were more infected. Following viral strains were detected in increasing frequency: Para-influenzae 3: 25 p. 100; RSV: 18 p. 10/; Adenovirus: 18 p. 100; Influenzae A: 13 p. 100; Influenzae B: 9 p. 100; Para-influenzae 1: 5 p. 100.
A total of 358 sera samples from blood donors of Tananarive city Hospital and outpatients of Medical Center (OSTIE) were assayed in ELISA method for HBs Ag: 3.35 p. 100 were found positive. Epidemiological characteristics were discussed.
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The immunogenicity of different antigens, containing rubella virus hemagglutinating (HA) membrane protein, was studied using live virus, beta-propiolactone-inactivated virus, detergent and lipid-free octamers and virosomes. Whole virus particles, live or inactivated, induced hemagglutination inhibition (HAI) antibodies in rabbits after one subcutaneous injection of 0.16 micrograms of HA protein. Hemagglutinin rosettes or virosomes failed to induce antibodies even at a dose of 120 micrograms. Apparently, the extraction of viral membrane hemagglutinin, for the preparation of a rubella subunit vaccine, led to destruction of the antigenicity responsible for the induction of hemagglutination inhibiting antibodies. These results are discussed in the light of earlier studies on the preparation of a rubella subunit vaccine.
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The hemagglutinin of rubella virus has been purified by differential centrifugation through a sucrose density gradient after disruption of purified virus with Tween 80-ether. The purified isolated hemagglutinin was than adsorbed on liposomes which had been prepared by mixing lecithin and dicetyl phosphate in a 3.5:1 molar ratio. The complex of hemagglutinin adsorbed on the virosomes had a higher sedimentation rate, enabling their separation from free hemagglutinin. It was thus possible to obtain a pure preparation of virosomes by rate zonal centrifugation in a sucrose density gradient containing 0.5 M NaCl. Immunoelectron microscopy showed aggregation of these virosomes with a rubella immune antiserum; this would suggest that the HA subunits are oriented in the same way as on the whole virus.
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The rates at which free, cationic and anionic liposomal forms of amikacin, netilmicin and tobramycin kill Pseudomonas aeruginosa were studied in vitro. Control inocula with no antibiotic yielded 6.76, 9.53 and 9.74 log CFU/ml at 0, 6 and 24 h, respectively. Empty anionic or cationic liposomes had no effect on bacterial growth. The killing rates of free antibiotics against the bacterial strain were not enhanced by the addition of either empty anionic or cationic liposomes. After 6 and 24 h of exposure at 1, 2 and 4 times the minimum inhibitory concentrations, free amikacin, netilmicin and tobramycin demonstrated a more rapid bactericidal effect than encapsulated anionic or cationic liposomes. The killing rates of liposomal aminoglycosides were lower than those of free aminoglycosides at identical concentrations, suggesting that only fractions of the encapsulated drugs were released from liposomes.