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Biomedical subjects

J Orfila

Publications and source records attributed to J Orfila.

At least 109 records · Page 6Linked to original sources
PubMed1982

[In vitro and in vivo activity of spiramycine on Chlamydia (author's transl)].

In vitro study of spiramycine action on C. psittaci and C. trachomatis demonstrates that this antibiotic is active in a concentration similar to that found in the serum of patients who have received an injection of 4 g. However, it should be noted that even with a higher dose, few inclusions are still present. On the other hand, the action of spiramycine on mice infected with C. psittaci is highly efficient. The difference between the in vitro results and the excellent in vivo results could be explained by an important accumulation of antibiotic in the tissue.

Animals↗
PubMed1980

Modifications of the envelope of Chlamydia psittaci during its developmental cycle: freeze-fracture study of complementary replicas.

Examination of complementary replicas obtained by freeze-fracture of Chlamydia psittaci revealed, at the level of the plasma membrane, a progressive differentiation of "crate-like formations," which likely correspond to transmembranal pores. Recognition of "early" and "late" stages observed in the intermediate bodies permitted detailed study of the developmental cycle of this chlamydia.

Cell Cycle↗
PubMed1979

[Use of a cryoultramicrotomy method for the purpose of studying chlamydial ultrastructure].

The method of cryoultramicrotomy was adapted for the study of the ultrastructure of HeLa and McCoy cells in monolayer cultures infected with Chlamydia, obligatory intracellular procaryotic parasites, the causative agents of ornithosis (strain Loth) and paratrachoma (strain LB 1). The cryosections were obtained by the fixation of the monolayer with 2.5% glutaraldehyde, by the gradual infiltration of precipitated cells with sucrose (0.6--1.2--1.8--2.3 M) prior to freezing in liquid nitrogen, and by the treatment of sections with 1% aqueous methyl cellulose solution before drying. This method ensured good preservation of both Chlamydia, in intracytoplasmic inclusions and host cells, as well as regular reproducibility of the results. Ultrathin sections showed a considerable polymorphism in the vegetative forms of Chlamydia, which was probably due to the structure of their cell walls. Chlamydia, were found to form small vesicle-like structures in the cavities of inclusions. The cell walls and granules inside the elementary bodies of the causative agent of ornithosis were stained with the use of phosphotungstic acid--HCl, pH 0.5.

Chlamydia↗
PubMed1978

Morphological and cytochemical study of Chlamydia with EDTA regressive technique and Gautier staining in ultrathin frozen sections of infected cell cultures: a comparison with embedded material.

The cryo-ultramicrotomy technique was applied to study the ultrastructure of Chlamydia using two strains: one of C. psittaci and one of C. trachomatis. It clearly appeared that in both strains reticulate bodies show a high degree of plasticity, contrasting with the rigid spherical appearance of elementary bodies. Ultrastructural cytochemical study shows DNA fibrils dispersed throughout the cytoplasm in reticulate bodies whereas DNA is condensed in a nucleoid in elementary and intermediate bodies. The EDTA regressive technique reveals ribonucleoproteins in reticulate and elementary bodies of both studied strains.

Animals↗
PubMed1975

[Morphological ultrastructural and immunological studies of a rickettsia isolated from a parrot (author's transl)].

A rickettsia isolated from a parrot was found by use of electron microscopic and serological technic to be a Coxiella burneti. In cell culture one can see a dramatic polymorphism and a Gram negative-like structure of the cell wall. They divide by binary fission with no appearance of a complexe cycle of development like the one described for Chlamydia psittaci. Many myelinic fibrils and altered Coxiella suggest that the host cell react very deaply.

Animals↗