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Biomedical subjects

R Negroni

Publications and source records attributed to R Negroni.

At least 73 records · Page 4Linked to original sources
PubMed1976

Depletion of complement in vivo and in vitro by extracts of Aspergillus fumigatus.

A new, nontoxic material extracted from Aspergillus fumigatus, is described with complement-depletion capacity both in vivo and in vitro. Extracts of the mycelium of A. fumigatus were found to haemolyse sheep red blood cells, to be lethal for mice and to convert C3 into its faster electrophoretic form when incubated with normal human serum. Conversion did not take place when purified C3 was used, suggesting that serum factors were required in the reaction. Adsorption of the extracts with activated carbon or heating at 100 degrees C for 30 min yielded detoxified materials devoid of both toxic and haemolytic properties but still capable of converting serum C3. In guinea pigs, administration of detoxified extracts was followed by complement depletion lasting not less than 48 h. Heating (100 degrees C for 30 min) extracts which had been previously detoxified by carbon adsorption resulted in a partial loss (40%) of their complement-inhibitory capacity indicating that part of the anticomplementarity of AFE was due to a heat-stable substance.

Animals↗
PubMed1976

[Study of the aerobic bacterial flora of onycolysis and paronychia caused by Candida].

The aerobic bacterial flora of 63 cases of onicolysis 78 of paronychis and 5 of onicomadesis produced by yeast-like fungus were studied. Bacterial isolation was carried out in nutrient agar with a concentration of 10 mug/ml of nystatin. These microorganisms were identified following the Otto Bier and Bailey & Scott's techniques (3, 1). Bacterial contamination was very frequent. One species or more were isolated from 93,6% of onicolysis and 97% of paronychis. The onicolysis presented the following flora: "Staphylococcus aureus" in 22 cases, "Staphylococcus epidermidis" in 21, Gram positive sporulated bacilli in 17, "Enterobacteriaceae" in 13, and "Pseudomona aeruginosa" in 6. The paronychial lesions showed the following flora: "Staphylococcus aureus" in 21 cases, "Staphylococcus epidermidis" in 26, Gram positive sporulated bacilli in 17, "Enterobacteriaceae" in 17 and "Pseudomona aeruginosa" in 3. It is important to emphasize that "Pseudomona aeruginosa" was isolated in a few cases of both types of candidal onixis, contrary to usual reports (2, 4, 9). No significant difference between the aerobic bacterial flora of the onicolysis and paronychia was found, that would give an explanation of the existence of these two clinical forms of candidal nails infection.

Bacteria↗
PubMed1976

[Preparation and study of a Paracoccidioides antigen needed for skin tests].

A cellular antigen from Paracoccidioides brasiliensis, obtained from the supernate of the disrupted yeast phase, was studied. It was prepared by a method similar to that for obtaining the spherulin from Coccidioides immitis. This antigen is composed of 55 mug/mg of polysaccharides, determined by the phenol method, and 7-8 mug/mg of protein, determined by Folin-Ciocalteu's technique. In vitro tests of antigenicity were done by immunodiffusion and complement fixation. The optimum dilution of the antigen was 0-5 mg/ml determined by microtiter complement fixation. The in vivo standardization of the cellular paracoccidioidin was performed on three groups of patients. The first was composed of 56 patients with mycologically proved paracoccidioidomycosis. The disease was active in 32 and clinically healed in 24 of this group. The second was composed of 15 cases of histoplasmosis with strong histoplasmin skin tests. The third group were 70 patients with no mycotic pulmonary diseases who had come from different zones in Argentina. Each individual was injected with 0-1 ml cellular paracoccidioidin (3 mg/ml), 0-1 ml of Fava Netto's antigen diluted 1/10, and 0-1 ml histoplasmin L48, diluted 1/100. The cellular paracoccidioidin skin test was positive in 44/56 (78.5%) patients with paracoccidioidomycosis. The Fava Netto's antigen gave 42 (75%) positive results and the histoplasmin skin tests gave 28 (50%) in the same group. Twenty-eight (50%) presented positive histoplasmin skin tests. The paracoccidioidin skin test was positive in 2 of the histoplasmosis group (13-3%) and the Fava Netto's antigen gave 3 positive results in the same group (20%). The histoplasmin skin test was positive in 32% of the individuals with no mycotic disease. Ten per cent of these exhibited positive reaction with both P. brasiliensis antigens. Of those paracoccidioidomycosis cases (Group 1) who had negative skin tests with 3 mg/ml of the cellular paracoccidioidin 7/10 gave positive skin tests when tested at a concentration of 8 mg/ml. Characteristic changes of cell medicated hypersensitivity were observed in the histopathological studies of the cellular paracoccidioidin skin test.

Antigens, Fungal↗
PubMed1975

Hemolytic, cytotoxic and complement inactivating properties of extracts of different species of Aspergillus.

Some of the biological properties of saline extracts of the mycelia of several species of the Aspergillus genus, namely, A. fumigatus, A. flavus, A. niger, A. nidulans, A. parasitucus and A. glaucus, were studied. Only the extract prepared from A. fumigatus was found to be hemolytic for sheep red blood cells. In contrast, all the extracts with the only exception of that of A. glaucus, had cytotoxic effects on Vero cells. Both, the hemolytic and cytotoxic constituents of the extracts were removable by adsorption with activated carbon. Heating of the extracts at 100 degrees C for 30 minutes also resulted in detoxification. In vivo studies, performed only with detoxified extracts of A. fumigatus, showed these were capable of depleting complement levels in guinea pigs. Complement inactivation was also found to occur in vitro and was cuased by all the extracts tested. Also triggered by the extracts was the conversion of serum C3 but not of purified C3, indicating that other serum factors are essential in the process. Despite the similarity in this respect with cobra venom factor, differences in activity after heating-negative in cobra venom factor-indicate that the complement inactivating substance/s present in the Aspergillus extracts differ from those of the snake product.

Animals↗