Absence of genotoxic activity of beta-myrcene in the in vivo cytogenetic bone marrow assay.

beta-Myrcene (MYR, 7-methyl-3-methylene-1,6 octadiene) is a peripheral analgesic substance and one of the major constituents of lemongrass oil (Cymbopogon citratus, Stapf), a plant widely used in Brazilian folk medicine. In the present study the genotoxicity of MYR was evaluated in vivo using the rat bone marrow cytogenetic assay. Male and female Wistar rats weighing 250 g (223 to 286 g) and 178 g (168 to 186 g), respectively, were used. Two or four rats of either sex were treated orally with MYR (0.1, 0.5 and 1.0 g/kg po), corn oil (negative control) and cyclophosphamide 30 mg/kg ip (positive control). Animals were sacrificed and bone marrow cells were harvested 24 and 48 h after MYR administration. The mitotic index and the frequency of chromosome aberrations were evaluated. Fifty metaphase cells were examined per animal. A dose related increase in mitotic index was observed 24-h after MYR administration. No evidence of MYR-induced clastogenicity was observed under the experimental conditions of this in vivo assay. The present results and previous negative findings of in vitro mutagenicity tests strongly indicate that MYR is not a genotoxic substance.

Absence of genotoxic activity of beta-myrcene in the in vivo cytogenetic bone marrow assay

beta-Myrcene (MYR, 7-methyl-3-methylene-1,6 octadiene) is a peripheral analgesic substance and one of the major constituents of lemongrass oil (Cymbopogon citratus, Stapf), a plant widely used in Brazilian folk medicine. In the present study the genotoxicity of MYR was evaluated in vivo using the rat bone marrow cytogenetic assay. Male and female Wistar rats weighing 250 g (223 to 286 g) and 178 g (168 to 186 g), respectively, were used. Two or four rats of either sex were treated orally with MYR (0.1, 0.5 and 1.0 g/kg po), corn oil (negative control) and cyclophosphamide 30 mg/kg ip (positive control). Animals were sacrificed and bone marrow cells were harvested 24 and 48 h after MYR administration. The mitotic index and the frequency of chromosome aberrations were evaluated. Fifty metaphase cells were examined per animal. A dose related increase in mitotic index was observed 24-h after MYR administration. No evidence of MYR-induced clastogenicity was observed under the experimental conditions of this in vivo assay. The present results and previous negative findings of in vitro mutagenicity tests strongly indicate that MYR is not a genotoxic substance

A serological investigation of rotavirus infections in a shanty town population in Rio de Janeiro.

The presence of antibodies against rotavirus was investigated by enzyme immunosorbent assay (ELISA) in two distinct groups of children living in a shanty town in Rio de Janeiro. One hundred and thirty six plasma samples were randomly collected from children of 0 to 33 months (first group) and 255 serum samples were collected from other 85 children at ages of 2, 6 and 9 months (second group). A high percentage of antibodies were found in the newborn children and this rate decreased progressively until the age of 11 months, after which it increased again. At the age of 7 months, geometric mean antibody titers increased indicating that infection had occurred.

Genomic heterogeneity of simian rotavirus SA11.

A preparation of simian rotavirus SA11 was shown to contain, in addition to the normal 11 genome segments, an RNA species with electrophoretic mobility slightly higher than that of segment 4. Limiting dilution passages allowed the separation of two virus clones distinguishable from each other by the electrophoretic mobility of that genome segment. Possible implications of this finding in virus behaviour and in the comparison of rotaviruses by RNA electrophoresis are discussed.

Comparison of polyacrylamide gel electrophoresis (PAGE), immuno-electron microscopy (IEM) and enzyme immunoassay (EIA) for the rapid diagnosis of rotavirus infection in children.

Detection of rotavirus RNA by polyacrylamide gel electrophoresis (PAGE) proved to be a highly sensitive and rapid diagnostic test. A comparison of this assay with immuno-electron microscopy (IEM) and enzyme immunoassay (EIA) in 245 faeces from children with gastroenteritis revealed complete agreement between the three assays in 238 (97.14%) samples. Among 75 samples positive in at least one of the three assays, negative results were observed in 5 (6.48%) by PAGE, in 6 (6.76%) by EIA and in none by IEM. Silver staining greatly increased the sensitivity of the PAGE assay. We conclude that although IEM remains the most sensitive and rapid rotavirus diagnostic assay, the PAGE technique has many advantages in its favour, including the non-requirement of expensive equipment, the use of only chemically defined reagents and the capacity to distinguish virus subgroup and variants and to detect non-crossreactive rotaviruses which are missed in serological assays.

Comparasion of polyacrylamide gel electrophoresis (PAGE), immuno-electron microscopy (IEM) and enzyme immunoassay (EIA) for the rapid diagnosis of rotavirus infection in children.

A evidenciacao da presenca de acido ribonucleico (ARN) viral por eletroforese em gel de policrilamida (EGPA) foi comprovada como um metodo altamente sensivel e rapido para o diagnostico de infeccoes por rotavirus. Uma comparacao desta prova com a imunomicroscopia eletronica (IEM) e com o ensaio imunoenzimatico (EIE) no exame de 245 fezes de criancas com gastroenterite revelou completa concordancia entre os tres ensaios em 238 (97.14%) amostras. Entre 75 amostras positivas pelo menos em um dos tres ensaios, resultados negativos foram observados em 5 (6.48%) por EGPA, em 6 (6.76%) por EIE e em nenhum por IEM. Coloracao pela prata aumentou consideravelmente a sensibilidade do ensaio por EGPA.Concluimos que embora a IEM ainda seja a prova mais sensivel e rapida para o diagnostico de infeccoes por rotavirus, o ensaio por EGPA tem muitas vantagens em seu favor, sendo as principais as de nao necessitar equipamentos caros, de empregar exclusivamente reagentes quimicamente definidos, de identificar grupos e variantes virais e de detectar amostras que nao possuindo antigenos comuns a maioria dos rotavirus, nao sao revelaveis por ensaios sorologicos