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Biomedical subjects

C M O'Hara

Publications and source records attributed to C M O'Hara.

5 recordsLinked to original sources
PubMed1992

Reorganization of the ependyma during axolotl spinal cord regeneration: changes in intermediate filament and fibronectin expression.

Changes in intermediate filament content and extracellular matrix material showed that the injury response of ependymal cells in lesioned axolotl spinal cord involves an epithelial-to-mesenchymal transformation, and that fibrous astrocytes are excluded from the remodeling lesion site. Antibody localization was used to visualize cytokeratin-, vimentin-, and glial fibrillary acidic protein- (GFAP-) containing intermediate filaments, as well as the adhesive glycoprotein fibronectin. In normal axolotl spinal cord cytokeratins were found near the apical surface of the ependymal cells. Transmission electron microscopic examination suggested that these cytokeratins were in tonofilaments. Cytokeratin expression was lost and vimentin production was initiated in ependymal cells 2-3 weeks following spinal cord injury. There was a period of approximately 1-2 weeks when cytokeratins and vimentin were co-expressed in vivo. This co-expression was maintained in vitro by culture on a fibronectin-coated substratum. As the central canal reformed, vimentin expression was lost. Ependymal cells lacked GFAP intermediate filaments, but GFAP was present in fibrous astrocytes of the neuropil and white matter. Following injury, GFAP localization showed that fibrous astrocytes disappeared from the remodeling lesion site and reappeared only after the ependymal epithelium reformed and newly myelinated axons were found. Fibronectin expression closely followed the expression of vimentin during mesenchymal ependymal cell outgrowth. These results suggest that the ependymal cell outgrowth requires changes in cell shape followed by changes in production of extracellular matrix.

Ambystoma↗
PubMed1992

Evaluation of the autoSCAN-W/A system for rapid (2-hour) identification of members of the family Enterobacteriaceae.

We evaluated the ability of the Baxter autoSCAN-W/A System (MicroScan Division, Baxter Diagnostics, Inc., West Sacramento, Calif.) to use the rapid (2-h) gram-negative identification panel for accurate identification of members of the family Enterobacteriaceae. At 2 h, 353 of 467 (75.6%) strains in a challenge set of biochemically typical and atypical stock cultures were correctly identified to genus and species. Another 76 (16.3%) strains were correctly identified to genus and species after the performance of recommended additional biochemical testing. Thus, at 24 h, 91.9% of the 467 strains were correctly identified. Twenty-two strains (4.7%) were identified to the correct genus but the incorrect species, and 16 strains (3.4%) were misidentified. Of these 16 strains, 9 were incorrect at 2 h, and 7 were incorrect after the additional testing. Because the system is based on fluorogenic substrates, no conventional tests were readily available with which to compare aberrant reactions. These results suggest that the autoSCAN-W/A with its rapid gram-negative panels is acceptable for the identification of the Enterobacteriaceae in a clinical microbiology laboratory.

Bacterial Typing Techniques↗
PubMed1975

An improved method for examination of cerebrospinal fluid cells.

A new collection technique allows cytologic examination up to 2 weeks after lumbar puncture without loss of cells or morphologic detail. Cerebrospinal fluid (CSF) was allowed to flow directly from a lumbar puncture needle into a solution of Carbowax in ethanol and was then processed with a cytocentrifuge. Two groups of patients were studied -- those undergoing spinal anesthesia and those having myelography for low back pain. Lymphocytes, polymorphonuclear neutrophils, and ependymal cells were regularly found in the CSF; a definite difference was found in the quantity and cell types in the two patient populations. The proposed method may be sensitive enough to aid in the identification of other neurologic diseases with low cell counts.

Adult↗
PubMedDate not supplied

Sputum fixatives: how safe is 50% alcohol?

It is believed that the following conclusions can be drawn from this study. 1) Fifty per cent ethyl alcohol fixative is bactericidal to 90 to 95% of the bacterial organisms present in the specimens submitted to cytology. 2) The fixative definitely appears to be selective against gram-negative organisms, both cocci and rods. 3) The fixative does not alter the ability of the organisms to take a characteristic stain. 4) The fixative does appear to alter the ability of the Histoplasma and the Cryptococcus to grow after a two-hour minimum fixation. No growth was noted after six weeks.

Bacteria↗