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R A Sawhney

Publications and source records attributed to R A Sawhney.

4 recordsLinked to original sources
PubMed1997

Distribution of cytokeratin markers in Barrett's specialized columnar epithelium.

BACKGROUND & AIMS: The cell of origin for Barrett's epithelium is unknown. A multilayered epithelium within Barrett's epithelium has been noted recently. To investigate the hypothesis that this multilayered epithelium may be a transitional stage between squamous and Barrett's epithelium, cytokeratin immunocytochemistry was used to examine normal squamous, Barrett's, and multilayered epithelium. METHODS: Seventeen endoscopic biopsy specimens taken from the squamo-Barrett's junction of 8 patients with Barrett's epithelium and 3 biopsy specimens from the gastroesophageal junction of 3 patients without Barrett's epithelium were investigated. Antibodies to cytokeratins 4 and 13 were used as markers for squamous differentiation, and antibodies to cytokeratins 8 and 19 were used as markers for glandular differentiation. Coded samples were evaluated by immunocytochemistry. RESULTS: In patients with Barrett's epithelium and control patients, staining with columnar markers was confined to either the Barrett's or the gastric columnar epithelium. Staining with squamous markers was confined to the adjacent squamous epithelium. In contrast, focal areas of multilayered epithelium amidst Barrett's epithelium stained with cytokeratin antibodies for both squamous and columnar epithelium. CONCLUSIONS: A focal multilayered epithelium within Barrett's epithelium that expresses concurrently both squamous and glandular cytokeratin markers is described. These findings suggest a multipotential cell as the cell of origin of Barrett's epithelium.

Adult↗
PubMed1996

Morphological characterization of the squamocolumnar junction of the esophagus in patients with and without Barrett's epithelium.

Barrett's esophagus is a metaplastic condition in which the normal stratified squamous epithelium of the distal esophagus is replaced by columnar epithelium. Our group has previously characterized a unique surface cell (the "distinctive cell") at the junction of squamous and Barrett's epithelium. This cell is notable for the simultaneous presence on its surface of both squamous and columnar cell features. The aims of our present study were, first, to evaluate prospectively the frequency with which Barrett's patients have the distinctive cell at the squamo-Barrett's junction; second, to further elucidate the characteristics of the distinctive cell; and third, to perform a combined morphological study of the squamo-Barrett's junction using scanning electron microscopy followed by transmission and light microscopy. We divided study patients into two groups: Group I consisted of Barrett's patients and group II of non-Barrett's control patients. Of eight group I Barrett's patients with junctional biopsies, three were noted to have the distinctive cell (37.5%). In contrast, this cell was not observed in any of the group II control patients. Biopsies in control patients as well as Barrett's patients without the distinctive cell revealed abrupt squamogastric or squamo-Barrett's junctions by scanning electron microscopy and light microscopy. In contrast, biopsies from the Barrett's patients with the distinctive cell revealed junctions that were not abrupt and had the distinctive cells overlying normal squamous epithelium. By scanning electron microscopy, the distinctive cells were flattened, polygonal cells with surface microvilli (a columnar cell feature) and were demarcated from one another by shallow depressions, or by intercellular ridges (a squamous cell feature). By transmission electron microscopy, the distinctive cells were cuboidal in shape with abundant apical microvilli and secretory vesicles. We have confirmed that distinctive cells are present in some Barrett's patients. This cell is a morphologic hybrid, sharing features of both squamous and columnar cells, and may be analogous to hybrid cells identified in other locations that undergo metaplasia (eg, the human cervix). Its origin may be the result of transformation of multipotential basal cells of squamous epithelial origin. We hypothesize that the distinctive cells may represent an intermediate stage in the development of Barrett's epithelium.

Adult↗
PubMed1995

Scanning electron microscopy of the human esophagus: application to Barrett's esophagus, a precancerous lesion.

In Barrett's esophagus, metaplastic columnar epithelium replaces the normal squamous epithelium. The importance of this lesion lies in the increased incidence of adenocarcinoma of the esophagus occurring in patients with Barrett's esophagus. We characterized the surface epithelial cells of Barrett's esophagus using quantitative scanning electron microscopy. Three distinct surface cell types, in addition to the globlet cell, were recognized in Barrett's epithelium: the gastric-like cell and the intestinal-like cell, both of which were similar to normal gastric and small intestinal surface cells, respectively, by quantitative scanning electron microscopy, and the variant cell which had a range of surface features. In four biopsy specimens from the squamo-Barrett's junction in three patients, we found the distinctive cell that had features intermediate between those of squamous and columnar epithelium. On the distinctive cell's surface there are two disparate structures not normally present on the same cell in the gastrointestinal tract: microvilli (a scanning electron microscopy feature of glandular epithelium) and intercellular ridges (a scanning electron microscopy feature of squamous epithelium). The surface characteristics of this cell were almost identical to those of cells found in the transformation zone of the uterine cervix, an area in which squamous epithelium physiologically replaces columnar epithelium. Scanning electron microscopy of Barrett's esophagus has increased our understanding of this precancerous lesion by showing striking cellular heterogeneity. It has also identified the distinctive cell which may represent an intermediate step in the development of Barrett's epithelium during which the surface characteristics of two different cell types, columnar and squamous, coexist in the same cell.

Barrett Esophagus↗