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Biomedical subjects

M Hommel

Publications and source records attributed to M Hommel.

At least 163 records · Page 9Linked to original sources
PubMed1981

Malaria: immunity and prospects for vaccination.

Malaria infections elicit a complex chain of cellular events which can, in some instances, lead to a state of immunity. Although there is strong evidence that a collaboration between specific antibodies and activated macrophages plays the central effector role in malaria immunity, alternative interpretations are possible. It is, for example, not known which malarial antigens are essential for triggering the critical effector functions and how these antigens are presented to the immune system. Under these circumstances, it is not surprising that the search for a vaccine against malaria has used rather empirical methods. Three invasive stages of the parasite (merozoites, sporozoites and gametes) have so far shown a potential efficiency in inducing protection in experimental models, but there is much to be done before vaccination can be an effective tool in malaria control.

Animals↗
PubMed1980

Inhibition of malaria parasite invasion into erythrocytes pretreated with membrane-active drugs.

Normal rhesus monkey erythrocytes were incubated with various membrane-active drugs (for 1 h at 37 degrees C) and after thorough washing, were exposed to infection with Plasmodium knowlesi in an invitro cultivation system. The ability of merozoites to infect with drug-pretreated erythrocytes was assessed both by counting the number of infected cells and by measuring the incorporation of [3H]isoleucine into parasite protein. Marked inhibition of invasion was observed with vinblastine and colchicine, at concentrations greater than 5 x 10(-4) M, respectively. At similar concentrations, cytochalasin B or amantadine had no apparent effect. The addition of 10(-3) M 3',5'-cAMP to the medium during the incubation in the presence of colchicine or vinblastine partially decreased the inhibitory effects. The effects of colchicine and vinblastine on parasite invasion may be correlated with a reversible alteration in erythrocyte conformation (spherocytosis) which occurs at similar drug concentrations to those above and which can be relieved by simultaneous incubation with cAMP. A possible mechanism of action is proposed.

Alkaloids↗
PubMed1980

Experimental infection of the squirrel monkey (Saimiri sciureus) with Plasmodium falciparum.

Seventy-six squirrel monkeys, Saimiri sciureus, caught in Guyana and French Guiana, were examined for their susceptibility to infection with a strain of Plasmodium falciparum. Twenty-nine serial transfers were performed, both in splenectomized and intact animals. After a period of "adaptation," the strain became more virulent for the squirrel monkey and high parasitemias were obtained in splenectomized animals. Frequently, such infections led to the death of infected animals. In intact squirrel monkeys, a consistent parasitemia was observed in most animals, but with a less regular pattern and a lower level of infection. Cultivation of infected erythrocytes from squirrel monkeys and human erythrocytes confirmed that the parasite had kept its infectivity for human cells after a long period of serial syringe-transfers in the squirrel monkey, and tht the virulence for the Saimiri remained unchanged after 1-mo, in vitro progagation in human erythrocytes. All erythrocytic forms of the schizogonic cycle were observed in the bloodstream, and there was a certain synchronicity of the cycle. Gametocytes were not detected in infected animals nor in in vitro cultures derived from a parasitized squirrel monkey. Our results indicate that all the squirrel monkey can be a useful host in the laboratory for studies on P. falciparum, and it may become more important as the supply of other species of monkeys diminishes.

Animals↗
PubMed1978

Isolation of malaria merozoites: release of Plasmodium chabaudi merozoites from schizonts bound to immobilized concanavalin A.

The ability of concanavalin A to bind erythrocytes but not malarial parasites was used for the development of a method of merozoite isolation: cells from infected blood were allowed to bind to a column of concanavalin A linked to Sepharose beads and merozoites naturally released by maturation of the schizonts bound to the gel were collected. The principle of this method allows its application to several Plasmodium species. The kinetics of merozoite production and the quality of the preparations (purity, infectivity, and ultrastructural morphology) were investigated by using Plasmodium chabaudi.

Animals↗
PubMed1978

The micro-ELISA technique in the serodiagnosis of visceral leishmaniasis.

The micro-scale Enzyme-linked Immunosorbent Assay (micro-ELISA) technique, with alkaline phosphatase as a marker enzyme, has been used for the serodiagnosis of human and canine visceral leishmaniasis, from foci in southern France. This technique which uses a soluble antigen is highly sensitive, with a degree of specificity slightly higher than that of the IFA. It is suggested that the micro-ELISA procedure can be added to the battery of serological techniques and would be particularly useful for large scale epidemiological studies of leishmaniasis.

Alkaline Phosphatase↗
PubMed1976

In vitro attachment of trypanosomes to plastic.

Description of an in vitro system for the study of the attachment of trypanosomes to polystyrene flasks by means of hemidesmosomes. This type of attachment, whose significance is so far unknown, reproduces a natural stage in the life cycle of medically important trypanosomatid flagellates in their vector.

Cell Adhesion↗