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Author

Roger Ladda

Bio: Roger Ladda is an academic researcher from University of Missouri. The author has contributed to research in topics: Plasmodium berghei & Plasmodium falciparum. The author has an hindex of 4, co-authored 4 publications receiving 84 citations.

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Journal ArticleDOI
TL;DR: Human and rodent trophozoites exhibited certain general similarities, but the origin of the body in P. berghei appeared to be more related to the external limiting membranes, and the erythrocytic forms of P. falciparum was found only in mature red cells.
Abstract: Electron microphotographs of early trophozoites of Plasmodium falciparum from human volunteers were compared with those of Plasmodium berghei in the rat. Human and rodent trophozoites exhibited certain general similarities: (1) both lacked a nucleolus, (2) pigment and smooth membrane vesicles were similar, (3) both forms exhibited double limiting membranes, (4) both lacked typical mitochondial forms, (5) both forms exhibited micropyle-type structures which are apparently specialized sites of absorption. Although multilaminated-membraned bodies (whorled-patterns) were present in both forms, P. falciparum differed in that these bodies appeared to be derived from the nuclear membranes; the origin of the body in P. berghei appeared to be more related to the external limiting membranes. The erythrocytic forms of P. berghei showed a great predilection for reticulocytes or younger red cells, but P. falciparum was found only in mature red cells.

26 citations

Journal ArticleDOI
TL;DR: Electron microphotographs are presented of trophozoites of Plasmodium berghei migrating from parasitized rat erythrocytes, and the structure of the merozoite (young troPHozoite) is compared with that of the maturing trophozite containing pigment and forming rings.
Abstract: Electron microphotographs are presented of trophozoites of Plasmodium berghei migrating from parasitized rat erythrocytes. The structure of the merozoite (young trophozoite) is compared with that of the maturing trophozoite containing pigment and forming rings. The significance of trophozoite migration, regarding the extracellular viability and infectivity of the trophozoite form, remains to be investigated.

14 citations

01 Jan 1966
TL;DR: The erythrocytic forms of P. berghei infections were studied in the polycythemic mouse in which erythropoiesis was markedly inhibited to better clarify the role of immature red cells.

14 citations


Cited by
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Journal ArticleDOI
TL;DR: The erythrocytic cycle of the human malaria parasite, Plasmodium, falciparum, was examined by electron microscopy and 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.
Abstract: SYNOPSIS. 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.

289 citations

Journal ArticleDOI
16 May 1969-Science
TL;DR: The mechanism whereby the gene for glucose-6-phosphate dehydrogenase deficiency confers selective advantage against malaria to heterozygous females, and thus may have attained the polymorphic frequency occurring in populations living in areas with endemic malaria, is investigated.
Abstract: Erythrocyte mosaicism occurs in females heterozygous for glucose-6-phosphate dehydrogenase deficiency. In blood from female children with acute Plasmodium falciparum malaria the parasite rate was 2 to 80 times higher in normal than in deficient erythrocytes. This may be the mechanism whereby the gene for glucose-6-phosphate dehydrogenase deficiency confers selective advantage against malaria to heterozygous females, and thus may have attained the polymorphic frequency occurring in populations living in areas with endemic malaria.

232 citations

Journal ArticleDOI
TL;DR: Current knowledge of the role of ferriprotoporphyrin IX in the antimalarial actions of quinoline drugs is summarized and currently available evidence in support of phospholipids as a second target for quinine, mefloquine and, possibly, the chloroquine-ferripro toporphyr in IX complex is evaluated.

211 citations

Journal Article
TL;DR: Electron micrographs of ultra-thin sections of erythrocytes taken from two Liberian children ill with Plasmodium falciparum malaria show that the appliqué forms of this parasite are clearly within the host cell.
Abstract: Electron micrographs of ultra-thin sections of erythrocytes taken from two Liberian children ill with Plasmodium falciparum malaria show that the applique forms of this parasite are clearly within the host cell. The general fine structure of the parasites resembles that of other mammalian malaria parasites, as does the mode of ingestion of host cell material by pinocytosis. Granules of haemozoin were usually found in small vesicles pinched off from the large food vacuole. Scattered through the cytoplasm of infected red cells were narrow clear clefts bounded on each side by two unit membranes. These probably represent the Maurer's clefts seen in light microscopy. The surface of infected erythrocytes was notably distorted, a phenomenon which may have a bearing on the stickiness of the infected red cells in human falciparum malaria and the segregation of these cells in the capillaries. Many uninfected erythrocytes showed a multiple alveolar, blister-like abnormality of a portion of the cell membrane; this was not seen in otherwise comparable blood from a case of P. ovale infection.

170 citations