Molecular genetic approach to cell proliferation control and neoplasia

A number of gene products involved in the control of cell proliferation fall into one of two classes: oncogenes and tumor suppressor genes. The same gene products have also been associated with malignant growth (tumors) caused by radiation, chemicals and tumor viruses. Here we describe our attempts to elucidate the molecular mechanisms underlying polyomavirus-induced cell transformation and the anti-tumor activity of glucocorticoid hormones. Wild type and mutant polyomavirus middle T (MT) overexpressing cell lines, generated with retroviral vector constructs, were used to investigate the role played by peptide growth factor primary response genes (fos, jun, myc, JE, KC) in viral transformation and to map the transduction pathway of the mitogenic signal of MT. Overexpression of MT leads to increased AP-1 (Fos/Jun) transcriptional complex activity. Transformation defective mutant analysis allowed the identification of sites in the MT molecule that are crucial for this activity. Two different approaches were used to investigate the molecular basis for glucocorticoids anti-tumor activity, namely: blind cloning of cDNAs and analysis of growth control genes in C6 glioma cell variants that are either hypersensitive (C6/ST1) or unresponsive to glucocorticoids (C6/P7). Four different glucocorticoid-regulated cDNA sequences were isolated using differential hybridization. A number of differentially expressed sequences were isolated from glucocorticoid-treated C6/ST1 cells by differential display (DDRT-PCR) and are currently being characterized. Expression of known growth control genes in C6/ST1 cells allowed the identification of important candidates for glucocorticoid hormone targets.

A method for screening drugs against the liver stages of malaria using Plasmodium gallinaceum and Aedes mosquitos

The radical cure of human malaria caused by Plasmodium vivax requires two drugs, i.e., a blood schizontocide such as chloroquine to clear the circulating parasites, and primaquine aimed at the liver stages (hypnozoites) responsible for the late relapses of this parasite. Primaquine is unique as a radical curative drug but is highly toxic. The only useful model currently available

Antimalarial activity of crude extracts from Brazilian plants studied in vivo in Plasmodium berghei-infected mice and in vitro against Plasmodium falciparum in culture

1. Ninety-five crude extrat obtained with either organic solvents or water from 48 Brazilian plants or parts of plants were evaluated experimentally as blood schizontocides. Seventy-three extracts wee obtained from 33 plants randomly collected using an empirical approach, and 22 from 15 "medicinal" plants. 2. The crude extracts were screened in vivo at up to 1.0g/Kg, po, for 4 days in mice infected with blood forms of Plasmodium berghei and parasitemia was determined on the fifth day. 3. Six plants, 2 randomly collected, Vernonia brasiliana and Eupatorium squalidum, and 4 "medicinal" plants, Acanthospermum australe, Esenbeckia febrifuga, Lisianthus speciosus, and Tachia guianensis, were partly active aginst the rodent malaria, i.e., they showed 40-50% inhibition of P. berghei multiplication. Forthy-two plants whose extracts presented no antimalarial activity are reported. 4. Four extracts with antimalarial activity were also tested in vitro using P. falciparum cultures and two of them, V. brasiliana and A. australe, were active. Extracts of V. brasiliana caused about 50% inhibition of parasite multiplication at relatively low doses (40ng/ml) as compared to chloroquine (30ng/ml) and quinine (50ng/ml). The relatively high percentage of positive results obtained here for "medicinal" plants vs randomly chosen plants demonstrates the effectiveness of the ethnopharmacological approach to drug testing

In vitro activity of natural and synthetic naphathoquinones against erythrocytic stages of Plasmodium falciparum

In an attempt to identify new antimalarial compounds we studied the blood schizonticide effect of chemically defined natural products which were isolated from plants (Bignoniaceae) or synthesized. Different concentrations of there drugs (up to 20 micronM) were incubated in vitro with blood forms of Plasmodium falciparum for 72 h. A total of 12 drugs of the naphtoquinones group were tested. Eight of them were isolated from plants (NP) and 4 synthesized (S). Three of the drugs (2 NP and one S) were very active and completely inhibited parasite growth at the higher concentrations used (20 micronM); 5 drugs were partially active (3S and 2NP) and 3 (NP) were totally inactive. Lapachol was among the drugs tested. Although it has been considered a potential antimalarial agent, it exhibited very low activity (20% inhibition of schizogony). The antimalarial activity of our naphthoquinones against drug-resistant strains was superior to that of chloroquine and quinine which were as controls. Two of the P. falciparum strains used for the tests were strongly chloroquine resistant. If these naphthoquinones prove to be active in vivo and are of low toxicity, they will be promising candidates for treatment of human malaria particularly since they are easily synthesized

Comprometimento cardiacao no sarampo. / Cardiac involvement in measles

A revisao da literatura mostra poucas citacoes de alteracoes cardiacas complicando o sarampo. Como na pratica o achado destas alteracoes cardiacas nos pareciam bastante frequentes, realizamos um estudo em 93 criancas de tres meses a oito anos de idade que foram internadas em nosso servico com diagnostico de sarampo. Em todas elas foram realizados estudos eletrocardiograficos na internacao e feito o seguinte pertinente. Em 86 criancas apareceram alteracoes do tracado, o que da um indice de 92,4%. Taquicardia sinusal e alteracoes de repolarizacao ventricular foram os achados mais frequentes. A porcentagem de alteracoes nos casos com ou sem complicacoes nao difere significativamente

Haemophilus influenzae resistentes a ampicilina. / Ampicillin resistance in Haemophilus influenzae

Desde alguns anos vem sendo descritos em todo o mundo cepas emergentes de Haemophilus influenzae resistentes a ampicilina.Apos uma analise ampla do problema, suas causas e consequencias, os Autores apresentam um estudo de 90 casos de criancas com meningite por Haemophilus influenzae, cepas estas que se mostraram resistentes a ampicilina em 64,4% dos casos, utilizandose o metodo de disco de Kirby-Bauer. E estudada e analisada a evolucao dessas criancas, das quais 60,34% tinham menos de um ano de idade. A terapeutica alternativa proposta foi o cloranfenicol e o resultado final revelou letalidade de 12,l%. Sao discutidas as implicacoes terapeuticas de tal achado e os diversos esquemas que podem ser adotados no sentido de se obter melhores resultados no tratamento das criancas infectadas com o Haemophilus