Chemotherapy of Plasmodium berghei

The avian malaria parasite Plasmodium gallinaceum causes marked structural changes on the surface of its host erythrocyte

Using a combination of atomic force, scanning and transmission electron microscopy, we found that avian erythrocytes infected with the avian malaria parasite Plasmodium gallinaceum develop approximately 60 nm wide and approximately 430 nm long furrow-like structures on the surface. Furrows begin to appear during the early trophozoite stage of the parasite's development. They remain constant in size and density during the course of parasite maturation and are uniformly distributed in random orientations over the erythrocyte surface. In addition, the density of furrows is directly proportional to the number of parasites contained within the erythrocyte. These findings suggest that parasite-induced intraerythrocytic processes are involved in modifying the surface of host erythrocytes. These processes may be analogous to those of the human malaria parasite P. falciparum, which induces knob-like protrusions that mediate the pathogenic adherence of parasitized erythrocytes to microvessels. Although P. gallinaceum-infected erythrocytes do not seem to adhere to microvessels in the host chicken, the furrows might be involved in the pathogenesis of P. gallinaceum infections by some other mechanism involving host-pathogen interactions.

Plasmodium berghei: electron spin resonance and lipid analysis of infected mouse erythrocyte membranes

Red blood cells from mice infected with Plasmodium berghei and from uninfected mice were labeled with stable, free radical derivatives of stearic acid. Electron spin resonance spectra of these samples showed that the degree of molecular order in these membranes decreased, and the rate of motion of the probe increased, with increasing levels of parasitemia. Parasitemia increased the ratio of unsaturated to saturated 18-carbon fatty acids, and decreased the percentage of arachidonic acid and of cholesterol. The effects of parasitemia on the membrane properties correlated with decreases in cholesterol/fatty acid ratios.

A Hausa herbal pharmacopoeia: biomedical evaluation of commonly used plant medicines

Biochemical analysis of a selected sample of the Hausa (northern Nigeria) medicinal flora is presented in order to assess potential chemotherapeutic values. Laboratory investigation, supplemented by previously published phytochemical constituent analyses of pertinent taxa, suggests that a number of disorders can be effectively treated by the Hausa practitioner. The Hausa herbal pharmacopoeia is analysed first with reference to its efficacy in the treatment of oral disease. Examined subsequently are Hausa plant medicines considered to be of potential value in the treatment and/or prevention of malaria infection, with particular attention focussed on the malaria symptom complex and parasite-host cell biochemistry. Results are discussed in the context of the adaptive potential of non-Western medical systems and the significance of this aspect for medical policy development programs.

Experimental studies of the potentiation of proguanil and pyrimethamine by dapsone using Plasmodium berghei in white mice

An accurate system with stringent criteria has been established to test antimalarial drugs and drug combinations against Plasmodium berghei in mice. Minimum effective doses for a number of antimalarial drugs have been determined when used in this system. Considerable potentiation of the activity of pyrimethamine and to a somewhat less extent of proguanil by dapsone has been demonstrated. The need to extend studies of these combinations to the parasites of human malaria is discussed in terms of establishing a safe chemoprophylactic regime in the presence of drug-resistant strains of parasites.