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Biomedical subjects

S G Langreth

Publications and source records attributed to S G Langreth.

6 recordsLinked to original sources
PubMed1979

Antigenicity of the infected-erythrocyte and merozoite surfaces in Falciparum malaria.

The antigenicity of altered structures induced by Plasmodium falciparum in the membranes of infected Aotus monkey and human erythrocytes was examined. Antisera were obtained from monkeys made immune to malaria. Bound antibodies were shown to be localized on the knob protrusions of infected erythrocytes of both human and monkey origin and from both in vitro and in vivo infections. Therefore, P. falciparum infection has produced similar antigenic changes in the erythrocyte surfaces of both man and monkey. Uninfected erythrocytes and all knobless-infected erythrocytes bound no antibody from immune sera. Strains of P. falciparum from widely different geographic areas that were cultured in vitro in human erythrocytes induced structures (knobs) which have common antigenicity. Merozoites were agglutinated by cross-linking of their cell coats when incubated with immune sera. The binding of ferritin-labeled antibody was heavy on the coats of both homologous and heterologous strains of the parasite, indicating that the merozoite surfaces of these strains share common antigens.

Animals↗
PubMed1979

Isolation of stages of the human parasite Plasmodium falciparum from culture and from animal blood.

Procedures for isolation of various forms of the asexual erythrocytic stages of the human parasite Plasmodium falciparum are outlined. The procedures employ the plasma expander Physiogel, which is composed of a chemically modified, partially hydrolysed gelatin dissolved in Ringer's lactate. Based on the observation that parasitized cells which are easily separable by this technique differ appreciably at the ultrastructural level, a mechanism by which separation occurs is proposed.

Animals↗
PubMed1978

Fine structure of human malaria in vitro.

The erythrocytic cycle of the human malaria parasite, Plasmodium, falciparum, was examined by electron microscopy. Three strains of parasites maintained in continuous culture in human erythrocytes were compared with in vivo infections in Aotus monkeys. The ultrastructure of P. falciparum is not altered by continuous cultivation in vitro. Mitochondria contain DNA-like filaments and some cristae at all stages of the erythrocytic life cycle. The Golgi apparatus is prominent at the schizont stage and may be involved in the formation of rhoptries. In culture, knob-like protrusions first appear on the surface of trophozoite-infected erythrocytes. The time of appearance of knobs on cells in vitro correlates with the life cycle stage of parasites which are sequestered from the peripheral circulation in vivo. Knob material of older parasites coalesces and forms extensions from the erythrocyte surface. Some of this material is sloughed from the host cell surface. The parasitophorous vacuole membrane breaks down in erythrocytes containing mature merozoites both in vitro and in vivo. Merozoite structure is similar to that of P. knowlesi. The immature gametocytes in culture have no knobs.

Animals↗
PubMed1977

Electron microscope cytochemistry of host-parasite membrane interactions in malaria.

Two membrane-bound enzymes were localized by electron microscope cytochemical techniques in Plasmodium lophurae and its host erythrocyte. Parasites were prepared by saponin lysis, French pressure cell lysis, or anti-red blood cell serum lysis; infected and uninfected erythrocyte ghosts were prepared by saponin or French pressure cell lysis. Enzyme incubations were performed on unfixed cells. Adenosinetriphosphatase (EC 3.6.1.3) activity was found on the inside of the ghost membrane and on the inside of the outer parasite membrane. NADH oxidase was found on the outside of the erythrocyte membrane and on the outside of the parasite outer membrane. The parasite plasma membrane was negative for both enzymes. The location of both enzymes on the outer parasite membrane were reversed from what one would have expected if the outer membrane had remained merely an invaginated erythrocyte membrane. It is concluded that the outer membrane, although derived from the red cell membrane, has been altered by its association with the malarial parasite.

Adenosine Triphosphatases↗