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Biomedical subjects

M Rommel

Publications and source records attributed to M Rommel.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Fine structure and development of Sarcocystis aucheniae in llamas].

Isolated cysts of Sarcocystis aucheniae of the llama (Lama glama) were fed to one dog and one cat. Only the dog excreted sporocysts, measuring 13.1-15.7 (15.0 +/- 0.54) X 9.0-11.3 (10.4 +/- 0.36) micron after 11 days for 21 days. A second cat, which had ingested meat of a llama containing macrocysts of S. aucheniae as well as sarcosporidial cysts visible only under a microscope also did not excrete sporocysts. The cysts of S. aucheniae are surrounded by a folded primary cyst wall forming cauliflower-like protrusions into the muscle fibre. The protrusions contain numerous microfilaments. In addition, the primary cyst wall forms numerous tiny vesicles. The parasitized muscle fibre is located in a large cavity within the normal muscle tissue. The cyst wall of S. aucheniae is similarly structured to that of S. gigantea of the sheep.

Animals↗
PubMed1984

Class-specific antibody responses in pigs following immunization and challenge with sporocysts of Sarcocystis miescheriana.

Sixteen pigs were each immunized by oral inoculation with 1000 sporocysts of Sarcocystis miescheriana at 8 weeks of age. Four equal groups were then challenged with 3 million sporocysts per animal at 40, 80, 120 or 160 days post-immunization (dpi). Host antibody responses were monitored using the enzyme-linked immunosorbent assay (ELISA) and the indirect fluorescent-antibody test (IFAT). When using class-specific ELISAs, dramatic increases in specific IgM-antibodies were observed at 21 dpi and increasing levels of IgG-antibodies were detected at 34 dpi. IgM-antibody titres dropped relatively quickly to insignificant levels, whereas IgG-antibody titres persisted at high levels until the end of the experiment. Following challenge, elevated levels of IgM-antibodies were detected, whereas IgG-antibody titres remained unchanged. The dynamics of the antibody titres detected by the IgG-IFAT closely corresponded to those detected by the IgG-ELISA. Despite the presence of specific antibodies at the time of challenge and the continued production of IgM-antibodies after challenge, the protective immunity decreased after 40 dpi and had disappeared by 120 dpi. Furthermore, none of the techniques used were suitable for the detection of specific antibodies during the early phase of acute sarcocystosis around 12 days after challenge.

Animals↗
PubMed1983

Persistence of acquired immunity to Sarcocystis miescheriana infection in growing pigs.

Sixteen 8-week-old pigs were each experimentally immunized by subclinical infections with 10(3) Sarcocystis miescheriana (syn. S. suicanis) sporocysts and 8 other pigs served as non-immunized controls. Four groups of pigs (each consisting of 4 immunized plus 2 control pigs) were then challenged by infection with 3 X 10(6) sporocysts at either 40, 80, 120 or 160 days post-immunization (dpi) to determine the persistence of the protective immunity against acute sarcocystosis. Pigs challenged 40 dpi demonstrated a solid immunity to lethal challenge and disease. They survived challenge following a mild fever phase whereas both controls died from acute disease. This immunity however, did not prevent the further establishment of parasitic cysts within the host musculature following challenge. The protective immunity against acute disease persisted to 80 dpi, but was not evident thereafter. At necropsy, the clinical and pathological findings in all pigs which had been subjected to challenge were consistent with anamnestic responses of sensitized hosts to re-infection.

Animals↗
PubMed1981

The Sarcocystis muris-infection as a model for research on the chemotherapy of acute sarcocystosis of domestic animals.

Twelve anticoccidial or antimalarial drugs were tested for their efficacy against various development stages of Sarcocystis muris in NMRI-mice. Schizogonic stages present in the liver from day 11 to 17 p.i. showed to be most sensitive to drug action. Sulfaquinoxaline plus pyrimethamine, zoalene and Bay g 7183 completely eliminated these stages. A strong though not 100 per cent efficacy was observed in experiments with primaquine. The other drugs tested were less (halofuginone, sulfadoxine plus trimethoprim) or not effective (sulfadimethoxine, amprolium, monensin, aprinocid, sulfaquinoxaline plus diaveridine) in the used dosages. In trials to improve the Sarcocystis muris-mouse-cat model it was found that in NMRI-mice the inoculation dose of 50 sporocysts resulted in the highest infection rate and intensity of the infection. By the application of less or more sporocysts or by repeated inoculations poorer infection rates and lower intensities of infection were achieved. Thymus deprived nude mice (NMRI-nu/nu) and the AKR/N-strain were the most susceptible animals in which infection rates of 100 and 95 per cent were achieved by the inoculation of 50 sporocysts. By the application of antilymphocytic serum, cyclophosphamide, irradiation or corticosteroids infection rates of 83, 92, 98 and 100 per cent, respectively, could be achieved in NMRI-mice. For future chemotherapeutical trials an inoculation dose of 50 sporocysts into irradiated NMRI-mice is recommended. It is suggested that the model is also suitable for the screening of drugs for their efficacy against exoerythrocytic schizonts of Plasmodium.

Acute Disease↗
PubMed1979

Sarcocystinae: nomina dubia and available names.

Examination of the original descriptions of the species of Sarcocystis in cattle, sheep, and swine, and of isosporid oocysts shed sporulated by dogs, cats, man, and other carnivores, has shown that it is not possible in most instances to identify unambiguously recently recognized taxa. The original descriptions are insufficient, and because no type specimens exist, could apply to two or more of the presently recognized taxa. We consider the following nomina dubia: Sarcocystis hirsuta S. miescheriana S. tenella S. cruzi S. bertrami Isospora bigemina (S. bigemina) I. hominis (S. hominis) I. buteonis (Frenkelia buteonis) Because the former type species, Sarcocystis miescheriana, is an indeterminate nomen dubium, we are proposing S. muris as the new type species. Historically, it was the first species described clearly and unambiguously even in the light of present knowledge, and the stages of its life cycle are probably completely known; it was the second species to be named. Old and recent descriptions are reviewed, and definitions are proposed for the following taxa: S. bovifelis S. bovicanis S. bovihominis S. ovifelis S. ovicanis S. muris (type species) S. suihominis S. suicanis S. equicanis Frenkelia microti F. glareoli for which neotypes will be prepared and deposited with designated institutions and curators. A new subfamily, Cystoisosporinae, is created.

Animals↗
PubMed1979

Pathomorphologic findings in short-tailed voles (Microtus agrestis) experimentally-infected with Frenkelia microti.

Following oral infection of Microtus agrestis with sporocysts of Frenkelia microti, transient focal necrosis and cellular infiltrations in the liver, hyperplasia of lymphoid organs, and inflammatory infiltrations in the heart, pulmonary veins, skeletal muscles and brain occurred during the first asexual multiplication period of the parasite in the liver. Frenkelia cysts were first observed in the brain 23 days after infection.

Animals↗
PubMed1979

Serological cross-reactions between toxoplasma and hammondia.

Toxoplasma and Hammondia infected mice, dogs, rabbits, and pigs were tested for Toxoplasma antibodies by means of 5 serological methods. All Toxoplasma infected animals showed Toxoplasma-specific antibodies. Only sera of Hammondia infected mice and dogs showed positive serological reactions with Toxoplasma antigen in the SFT, CFT, and ELISA. IFAT and IHA, however, proved to be Toxoplasma-specific. The influence of Hammondia infections on the Toxoplasma serology is discussed.

Animals↗
PubMed1978

[Comparative review of the developmental biology of the genera Sarcocystis, Frenkelia, Isospora, Cystoisospora, Hammondia, Toxoplasma and Besnoitia (author's transl)].

A review is given of the advances in our knowledge of the developmental biology of the so-called cyst-forming coccidia in the years from 1974 to 1978. Until 1970 only 6 Isospora species were known to occur in cats, dogs and men. After the discovery of the coccidian nature of the genera Toxoplasma, Sarcocystis, Besnoitia and Frenkelia, and after the discovery of the new genus Hammondia the number of known species rose to over 30. In addition it could be shown that also birds of prey, owls and reptiles serve as final hosts for several Sarcocystis and Frenkelia species. The coccidia with isosporoid oocysts can be classified into two major groups: Species with gamogony and sporogony in the final host (Sarcocystis, Frenkelia) and species with schizogony and gamogony in the final host and sporogony on the ground (Isospora, Cystoisospora, Hammondia, Toxoplasma, Besnoitia). The subdivision of the first group into the genera Sarcocystis and Frenkelia based on the localization of their cysts in the musculature and in the brain, respectively, cannot be upheld in the future. Their classification into organisms with small cystozoites of about 7 microm with birds or reptiles as final hosts (Sarcocystis and Frenkelia species of rodents) and those with large cystozoites of about 15 microm and mammals as final hosts (Sarcocystis spp. of domestic animals and rodents) would be more significative. The second group can be subdivided into monoxenous species (Isospora), species with an optional intermediate host in which no or only slight multiplication occurs (Cystoisospora) and in genera with a multiplication in two phases in the intermediate host (Hammondia, Toxoplasma, Besnoitia). The nomenclature of single species is very controversial. As an example the controversial apprehension of the taxonomy of the Sarcocystis species of cattle is discussed. An application has been submitted to the International Commission for the Zoological Nomenclature to delcare a number of names as nomina dubia and to introduce unambiguous names for those organisms for which type specimens are available.

Animals↗