Gene silencing of HIV chemokine receptors using ribozymes and single-stranded antisense RNA

The chemokine receptors CXCR4 and CCR5 are required for HIV-1 to enter cells, and the progression of HIV-1 infection to AIDS involves a switch in the co-receptor usage of the virus from CCR5 to CXCR4. These receptors therefore make attractive candidates for therapeutic intervention, and we have investigated the silencing of their genes by using ribozymes and single-stranded antisense RNAs. In the present study, we demonstrate using ribozymes that a depletion of CXCR4 and CCR5 mRNAs can be achieved simultaneously in human PBMCs (peripheral blood mononuclear cells), cells commonly used by the virus for infection and replication. Ribozyme activity leads to an inhibition of the cell-surface expression of both CCR5 and CXCR4, resulting in a significant inhibition of HIV-1 replication when PBMCs are challenged with the virus. In addition, we show that small single-stranded antisense RNAs can also be used to silence CCR5 and CXCR4 genes when delivered to PBMCs. This silencing is caused by selective degradation of receptor mRNAs.

Analgesic and antipyretic effects of Dodonaea angustifolia and Salvia africana-lutea

Water extracts of Dodonaea angustifolia L. and Salvia africana-lutea L., were investigated for analgesic and antipyretic activities using acetic acid writhing and hot plate tests, and lipopolysaccharide (LP)-induced pyrexia test in mice and rats, respectively. D. angustifolia and S. africana-lutea significantly inhibited acetic acid-induced writhing and also significantly delayed the time of reaction of mice to thermal stimulation produced by the hot plate. D. angustifolia and S. africana-lutea significantly reduced fever induced by LP. Paracetamol produced similar effects to D. angustifolia and S. africana-lutea on the acetic acid-induced writhing but has no effect on hot plate-induced nociception and on pyrexia produced by LP. These data indicate the analgesic and antipyretic potential of D. angustifolia and S. africana-lutea.

Effects of Tarchonanthus camphoratus and Eriocephalus africanus on nociception in mice and pyrexia in rats

The affects of water extracts of the leaves of T. camphoratus and E. africanus on acetic acid- and hotplate-induced nociception and lipopolysaccharide-induced pyrexia were investigated. The writhing induced by acetic acid was significantly attenuated by T. camphoratus (50-100 mg/kg, i.p.), and E. africanus (50-200 mg/kg, i.p.). Similarly, the pain produced by the hot-plate was significantly antagonized by T. camphoratus (100 mg/kg, i.p.), and E. africanus (50-100 mg/kg, i.p.). T. camphoratus (100 mg/kg, i.p.), and E. africanus (100-200 mg/kg, i.p.) significantly attenuated the fever produced by the bacterial endotoxin (lipopolysaccharide, 50 microg/kg, i.m.). Paracetamol (500 mg/kg, i.p.), produced similar effect to T. camphoratus and E. africanus on acetic acid-induced writhes but did not affect the pain and the fever produced by the hot-plate and lipopolysaccharide respectively, to any significant extent. These results indicate that both T. camphoratus and E. africanus have analgesic and antipyretic properties.