PfEMP1 is a family of cytoadhesive surface antigens expressed on erythrocytes infected with Plasmodium falciparum, the parasite that causes the most severe form of malaria. These surface antigens play a role in immune evasion and are thought to contribute to the pathogenesis of the malaria parasite. Previous studies have suggested a role for a specific subset of PfEMP1 called "group A" in severe malaria. To explore the role of group A PfEMP1 in disease, we measured the expression of the var genes that encode them in parasites from clinical isolates collected from children suffering from malaria. We also looked at the ability of these clinical isolates to induce rosetting of erythrocytes, which indicates a cytoadhesion phenotype that is thought to be important in pathogenesis. These two sets of data were correlated with the presence of two life-threatening manifestations of severe malaria in the children: impaired consciousness and respiratory distress. Using regression analysis, we show that marked rosetting was associated with respiratory distress, whereas elevated expression of group A-like var genes without elevated rosetting was associated with impaired consciousness. The results suggest that manifestations of malarial disease may reflect the distribution of cytoadhesion phenotypes expressed by the infecting parasite population.
The aim of the study was to ascertain the analgesic properties of Mondia whytei
roots and to isolate and characterize the active constituents. Bioactivity guided
fractionation of the chloroform root extract yielded stigmasterol and 9-hexacosene.
Stigmasterol (15 mg/kg) and 9-hexacosene (30 mg/kg) significantly (p<0.05)
inhibited chemical nociception induced by intraperitoneal acetic acid. Stigmasterol
(7.5, 15, 30 and 100 mg/kg) dose dependently reduced the time spent in pain behavior
in both the early and late phases of the formalin test. 9-hexacosene dose
dependently caused significant (p<0.001) antinociceptive effect on the late phase of
the formalin test. Co-administration of naloxone failed to antagonize the analgesic
activity of stigmasterol and 9-hexacosene in the formalin test. We concluded that
both stigmasterol and 9-hexacosene possess potential analgesic effects which are
most likely mediated by their anti-inflammatory activities rather than through
opioid receptor system.