Biomedical subjects

C Mory

Publications and source records attributed to C Mory.

22 records · Page 2Linked to original sources

PubMed1984

Unconventional modes for STEM imaging of biological structures.

In this paper recent developments are discussed in instrumentation and methodology associated with scanning transmission electron microscopes (STEM), which are of great potential interest for solving structural and chemical problems in biological specimens. After describing the main features of the instrument, an attempt is made to define which type of signal acquisition and processing is best suited to obtain a given type of information. Starting with a definition of cross sections of interest, a discussion follows of methods using angular selection, energy selection of the transmitted beam, and several ways of signal mixing. More specific attention is devoted to two main modes of processing signals: ratio contrast, which emphasizes slight changes in scattering factors, rather independent of thickness variations; and elemental mapping, which provides semi-quantitative information on the distribution of low Z elements of great significance in biological specimens. Data relevant to typical biological objects are presented and discussed; they allow for the definition of the capabilities and limitations of these methods. These unconventional imaging modes define a new attitude for improving the efficiency of this modern generation of electron microscopes.

Animals↗

PubMed1984

A STEM approach to the study of the proteinaceous architecture of a ribosome.

We used a high-resolution STEM to attempt to recognize the spatial localization of the macromolecular components of ribosomes isolated from Tetrahymena pyriformis. Images obtained either by the annular dark field detector or by the ratio-contrast mode (Z-contrast) show a ribosome as constituted of rounded dark areas, the number and size of which are compatible with those of the protein molecules recognized by biochemistry. Images of different ribosomes, when similar orientations are observed, exhibit a roughly constant pattern of the dark areas. A set of images of a tilted ribosome allows to recognize that some masses are in fact two more superimposed components. We propose that the dark areas represent essentially the proteinaceous architecture of the ribosome.

Animals↗

PubMed1983

[Haemophilus influenzae and parainfluenzae in children. A retrospective study of 52 cases].

Fifty-two children hospitalized in the Pediatric service of a general hospital between January 1978 and December 1979 were found to be infected with Haemophilus influenzae or para-influenzae (43 with H. influenzae and 9 with para-influenzae). Most of these children (34/52) were less than 4 years of age. The localizations of infections were as follow: 5 meningitis with satisfactory resolution except for 1 who developed slight deafness, 1 epiglotitis, 11 pneumonias or bronchopneumonias, 1 arthritis, 10 otitis medias, 6 conjunctivitis, 3 sinusitis, 10 upper airway infections and 1 neonatal infection. On 8 of these cases the patients were felt to be carriers of H. influenzae or para-influenzae, the signs and symptoms beeing not related to these bacteria. These results are compared with those found in the literature.

Child↗

PubMed1981

Improved visualization of single- and double-strained nucleic acids by STEM.

Annular dark field STEM images have been used to visualize nucleic acid molecules positively stained with uranyl acetate. The regular distribution of uranium clusters makes clearly visible the existence of segments of double and single strands on partially denatured RNA molecules. Unpaired regions, as short as about 8 nm, are detectable by this combination of a highly efficient imaging mode and a well adapted preparation technique.

DNA, Circular↗