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F Miltgen

Publications and source records attributed to F Miltgen.

At least 55 records · Page 3Linked to original sources
PubMed1986

The chemotherapy of rodent malaria XLI. Causal prophylaxis. Part V. Effect of mefloquine on exoerythrocytic schizogony in Plasmodium yoelii yoelii.

Previous studies using mefloquine in rodents have suggested that this compound has no effect on pre-erythrocytic schizogony. In the present study, direct observations on 46-hour-old pre-erythrocytic schizonts of P. yoelii in the liver of rats have shown that mefloquine does induce recognizable changes in the peripheral, enzyme-containing vesicles but that these are insufficient to hinder the maturation of the parasites, thus confirming that this compound has no causal prophylactic value.

Animals↗
PubMed1985

Complete development of hepatic stages of Plasmodium falciparum in vitro.

An in vitro model was developed to study the hepatic phase of Plasmodium falciparum, the only malaria parasite lethal to man. Primary cultures of human hepatocytes were inoculated with sporozoites of Brazilian and African strains of P. falciparum. On days 1 through 7 after inoculation examination of fluorescence-labeled and Giemsa-stained preparations demonstrated the presence of many intracellular parasites. In three separate sets of experiments all cultures were found to be infected with as many as 650 liver schizonts measuring up to 40 micrometers. After the addition of red blood cells, intraerythrocytic forms of P. falciparum were detected on days 12 and 13 by an immunofluorescence assay, indicating that the hepatic cycle had been completed in vitro.

Animals↗
PubMed1985

[Cultivation of exo-erythrocytic schizonts of rodent Plasmodium in hepatocytes: a new experimental model for chemotherapy of malaria].

An in vitro experimental model using primary cultures of laboratory bred Thamnomys gazellae's hepatocytes and Plasmodium yoelii yoelii' sporozoites was set up for chemotherapeutic studies. The surface of the culture was reduced (0.5 cm) and allowed the rapid performance and analysis of schizonticide activity tests, with a reduced biological material (Rodents, Anopheles, sporozoites). Fifteen compounds were tested. When activity of molecules is known in vivo, both results in vivo and in vitro are parallel.

Animals↗
PubMed1984

[Obtaining hepatic stages of Plasmodium falciparum in vitro].

Sporozoites of Plasmodium falciparum, obtained by membrane feeding of Anopheles freeborni or A. stephensi with cultured gametocytes, were used to infect monolayers of human hepatocytes. Fluorescent labelling with an African serum as well as Giemsa staining performed from day one to day 7 of cultures, demonstrated the presence of numerous hepatic schizonts measuring up to 40 micron.

Animals↗
PubMed1984

Species- and stage-specific antigens in exoerythrocytic stages of Plasmodium falciparum.

Numerous exoerythrocytic forms of Plasmodium falciparum ( PFEEF ) were obtained from the liver of the South American monkey, Cebus apella, for analysis of the antigens on this stage. As antigen for the fluorescent assay, 5-micron sections of liver fragments collected on day 5 following sporozoite inoculation and fixed in Carnoy's solution or kept in liquid nitrogen were used. Two types of fluorescent labeling of the PFEEF were identified: diffuse and peripheral. Each of 23 sera from individuals with P. falciparum infection acquired naturally by mosquito bite showed the diffuse and peripheral patterns of fluorescence at low serum dilutions (i.e., 1:10-1:100), but only peripheral staining at higher serum dilutions (i.e., 1:200-1:1,600). All other polyclonal sera tested showed only the diffuse pattern of fluorescence whatever the serum dilution used; this was true for P. falciparum infections acquired accidentally by blood transfusion, heterologous human infections with P. vivax, P. ovale, P. malariae or P. cynomolgi, and experimental animal infections with P. berghei, P. gallinaceum, or P. cynomolgi. Fluorescent antibody titers on PFEEF were generally 1-4 dilutions lower than on blood stages. No age-dependent pattern of fluorescence titers was found in 30 sera from individuals ranging in age from 2-78 years living in a malaria-endemic area. Twenty-six monoclonal antibodies directed to P. falciparum blood stages which reacted at high titers with rings, schizonts, merozoites, and gametocytes did not react with PFEEF antigen even when using the undiluted ascitic fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

[Studies on Plasmodium atheruri].

Plasmodium atheruri, a parasite of the African porcupine Atherurus africanus, is infective to splenectomised laboratory Rats and Mice, to Hamsters and to 2 exotic rodents which are easily bred in captivity: Calomys callosus and Meriones unguiculatus. Sporogony develops in Anopheles stephensi fed on Atherurus and on laboratory rodents; it is similar to that of the Rodent Plasmodia. Exoerythrocytic schizogony usually lasts 4 to 6 days but schizonts have been found in the liver of a porcupine at day 8. Schizogony in the blood (induced by inoculation of infected blood or by injections of sporozoites) follows two stages which are morphologically distinct: a) acute infections developing in clean Atherurus, following splenectomy of infected Atherurus or in laboratory rodents; it is characterized by large trophozoïtes, schizonts with 8 to 16 merozoites, gametocytes and infectivity to Anopheles. b) chronic infection which only occurs in the blood of Atherurus and follows the acute stage 15 to 21 days after its onset; it is characterized by small trophozoites and schizonts producing 4 merozoites. Thus it is thought that the chronic stage only occurs in the natural host when it is immunized. We think that, in nature, chronic schizogony maintains the parasitaemia through periods of low transmission and is followed by "recrudescences". The mechanisms that trigger the "recrudescences" are unknown but are probably connected with a decrease in the immune status of the host.

Animals↗
PubMed1983

The chemotherapy of rodent malaria, XXXIV. Causal prophylaxis Part III: Ultrastructural changes induced in exo-erythrocytic schizonts of Plasmodium yoelii yoelii by primaquine.

Wistar rats were injected intravenously with sporozoites from Anopheles stephensi infected with Plasmodium yoelii yoelii. The animals were subsequently treated with primaquine at doses of 30, 50 or 100 mg kg-1 at various times. Liver biopsies were made and the exoerythrocytic schizonts examined by light and electron microscopy between 45 and 50 hours. The action of the drug appeared to be principally on the parasite mitochondria, the membranes of which became thickened, then proliferated into multiple layers. Finally the whole organelles swelled up losing all structural organisation. Other parasite membranes were affected similarly and the peripheral enzyme granules disappeared. Following treatment the small, disrupted schizonts were apparently absorbed by their host cells which appeared unaffected by primaquine.

Animals↗
PubMed1983

[In vitro infestation of human hepatocytes by sporozoites of Plasmodium vivax: schizogony and liberation of merozoites capable of infesting human erythrocytes].

Human hepatocytes obtained by perfusion of a liver biopsy fragment, were infected in vitro with Plasmodium vivax sporozoites raised in Anopheles stephensi. On day 7 of culture, numerous hepatocytic schizonts ranging in size from 5 to 35 micrometers were observed. The schizont maturation was complete and led to the release of invasive merozoites as shown by in vitro infestation of human red cells layered on the hepatocytes cultures.

Animals↗
PubMed1982

[In vitro infestation of adult thamnomys hepatocytes with Plasmodium yoelii sporozoites; schizogony and release of infecting merozoites].

Hepatocytes isolated from an African rodent, Thamnomys gazellae, by perfusing the liver with a solution of collagenase were cultured in modified MEM medium, and infected in vitro by sporozoites of the 17 X strain of P. y. yoelii. 48 hrs. later, schizonts measuring 30 to 40 microns on average were observed in all cultures. Injection of culture supernatant, harvested on day 3, into Mice, was followed by a parasitaemia demonstrating that viable merozoites had been released by the schizonts.

Animals↗
PubMed1982

[Exo-erythrocytic schizogony of plasmodium falciparum in the monkey Cebus apella (author's transl)].

P. falciparum sporozoïtes obtained by membrane-feeding of Anopheles stephensi with blood containing gametocytes were injected intravenously to the Monkey Cebus apella. 5 days later, a great number of exo-erythrocytic stages were found in the liver, and appeared to be morphologically similar to those described in man. The host specificity of the sporozoïte seems less restricted than that of the merozoïte.

Animals↗
PubMed1982

[Culicoides nubeculosus, an experimental vector of a new trypanosome from psittaciforms: Trypanosoma barkeri n. sp].

Two out of four Psittacula roseata from Thaïland harboured a trypanosome: T. bakeri n. sp. Laboratory reared Culicoides nubeculosus were fed on one of them. The trypanosomes developed well in this arthropod and metatrypomastigotes were observed five days after the blood meal. The inoculation of crushed Culicoides into one of the trypanosome-free Psittacula gave rise to a parasitaemia after a prepatent period of eleven days. This provides more evidence that Culicoides can act as vectors of avian trypanosomes.

Animals↗
PubMed1981

[Parahaemoproteus desseri n. sp.; gametogony and schizogony in the natural host: Psittacula roseata from Thailand, experimental sporogony in Culicoides nubeculosus (author's transl)].

The gametogony and the tissue schizogony of Parahaemoproteus desseri are described in the natural host: Psittacula roseata; the schizonts develop in muscle fibres; they are large (up to 900 micrometer) and often sausage shaped with pseudo-septa. Experimental sporogony was studied in laboratory bred Culicoides nubeculosus (Ceratopogonidae). Oocysts are small and give rise to a small number of sporozoites. The morphological characteristics of the schizonts of our Parahaemoproteus are very similar to those of schizonts of Arthrocystis galli and therefore it is possible that the two genera are synonymous.

Animals↗
PubMed1979

[New data on the biology of gametocytes of Plasmodium yoelii yoelli gathered from morphological characteristics indicating their age].

A morphological study has been made of the gametocytes of P. yoelii (a parasite of Rodents belonging to the "vivax" group). The authors distinguish 4 types chronologically ordered. Moreover, morphology enables one to predict their infectivity. The morphological analysis represents a tool leading to new data on the biology of gametocytes: loss of infectivity as soon as the parasitaemia becomes high; infectivity restricted to the young stages; concentration of young stages in the blood ingested by the Mosquitoes; short periodicity and short lived infectivity.

Animals↗
PubMed1977

[The schizogony of Polychromophilus (Haemoproteidae), cosmopolitan parasite of Microchiroptera].

The schizogony of Polychromophilus was partially known by the findings of Schingarew, Mer and Goldblum who demonstrated microschizonts in the reticulo-endothelial tissue. The present work completes these data by showing the presence of macroschizonts in the lungs of both African and European species. These schizonts are characterized by their large size, the hypertrophy of the host cell and its nucleus and the evolution of the parasite apparently slow when young, becoming rapid later.

Animals↗
PubMed1975

[Blood relapses and modifications of the pre-erythrocytic shizonts of Plasmodium yoelii using ethionine].

Injections of DL-ethionine during the preerythrocytic period of Plasmodium yoeli in Thammomys were followed by: 1. A delayed prepatent period; 2. A relapsing parasitaemia with alternatively positive and negative blood at subinoculation of clean mice; 3. A peculiar morphology of the exoerythrocytic schizonts which remain small with a scanty cytoplasm and very few large nuclei. Although the authors consider the origin of the relapses to be the rupture of delayed hepatic schizonts under the influence of ethionine, none were found after the 5th day.

Animals↗