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Biomedical subjects

C Beek

Publications and source records attributed to C Beek.

6 recordsLinked to original sources
PubMed1993

Endocrine cells in colorectal adenocarcinomas: incidence, hormone profile and prognostic relevance.

The occurrence of endocrine cells in 350 cases of colorectal adenocarcinoma was studied by immunohistochemistry for chromogranin A (CGA). The hormone profile of endocrine tumor cells, the correlation between endocrine differentiation and presence of other colorectal epithelial-cell lineages and the prognostic relevance of endocrine differentiation in colorectal cancer were investigated. CGA-positive tumor cells were found in 30% of cases, 21% showing moderate positivity and 9.0% extensive positivity. Of CGA-positive tumors, 70% additionally produced neurohormones, mainly indigenous to normal colorectal epithelium: 55% showed immunoreactivity for glucagon-like substances, 20% for serotonin and 10% for somatostatin, PYY and HCG. No immunoreactivity was found for various neurohormones not normally produced by colorectal endocrine cells. CGA-positive tumors tended to be more aggressive than CGA-negative tumors. Especially, tumors with extensive CGA positivity showed shorter survival, which was most apparent within Dukes' stage C. In multivariate analysis, extensive CGA positivity was an independent indicator of poor prognosis. CGA immunoreactivity significantly correlated with mucin production, but not with expression of secretory component (SC), a columnar-cell marker. Mucin production significantly correlated with SC expression. Tumors positive for CGA but not for mucin and/or SC showed the worst prognosis. SC expression was a relatively favorable feature, and mucin-producing tumors showed intermediate behavior.

Adenocarcinoma↗
PubMed1990

Origin of basement membrane type IV collagen in xenografted human epithelial tumor cell lines.

The origin of basement membrane (BM), deposited in epithelial neoplasms, was studied in xenografts of human tumor cell lines in nude mice and rats. Cell lines were chosen that in vitro do (WISH, KB) or do not (5583-E; HT-29) produce BM components, more specifically, type IV collagen. Basement membrane deposition was studied by immunohistochemistry, using species cross-reactive polyclonal anti-human type IV collagen antiserum, mouse- and rat-specific polyclonal anti-mouse type IV collagen antiserum, human-specific monoclonal anti-type-IV collagen antibody, and by in situ hybridization, using a 32S-labeled species cross-reactive cDNA probe, specific for type IV collagen mRNA. In the xenografts, species-cross-reactive anti-type-IV collagen antiserum demonstrated the presence of irregular and discontinuous BM. In 5583-E and HT-29 xenografts, only murine type IV collagen epitopes were detected. In contrast, in WISH and in KB xenografts, the BM stained human as well as murine type IV collagen epitopes. By in situ hybridization, type IV collagen mRNA was detectable in stromal cells only in 5583-E and HT-29 xenografts, but in both epithelial and stromal cells in WISH and KB xenografts. These results indicate that in this model system epithelial tumor cells and stromal (mesenchymal) cells are involved in the production and deposition of a BM.

Animals↗
PubMed1989

Monoclonal antibodies to native basement membranes reveal heterogeneous immunoreactivity patterns.

In this paper we describe the development of basement membrane (BM) reactive monoclonal antibodies (MA), by immunization of mice with intact denuded BM. The MA raised against denuded amniotic BM (clones 1052, 1053 and 1065) showed heterogeneous staining patterns. MA 1052 and 1053 reacted with epithelial BM of the epidermis and epidermal adnexa and furthermore with the epithelial alveolar BM in the lung and the superficial part of the epithelial BM in the gastrointestinal tract. MA 1065 showed immunoreactivity with the epithelial BM of epidermis and epidermal adnexa and the epithelial BM of trachea and oesophagus, and furthermore pericellular staining of the basal keratinocytes and basal corneal epithelial cells. MA 1087, raised against human glomerular BM, showed immunoreactivity with all BM, except the central epithelial BM in the cornea. The precise localization of the target epitopes in the BM was investigated on chemically cleaved human skin. Reactivity for the MA occurred predominantly in the BM lamina adherent to the dermis, suggesting that the target epitopes reside in the lamina densa and/or lamina fibroreticularis. We furthermore examined the nature of the epitopes by preincubation of tissue sections with various enzymes prior to immunohistochemistry. The reactivity of the target epitopes was not affected by bacterial collagenase, but after various protease treatments the reactivity disappeared, suggesting that the epitopes are not localized on the triple helical part of collagenous proteins.

Amnion↗
PubMed1987

Human specific anti-type IV collagen monoclonal antibodies, characterization and immunohistochemical application.

This paper describes two new monoclonal antibodies reactive with human specific type IV collagen epitopes in frozen as well as routinely fixed and processed tissue sections. The antibodies (1042 and 1043) were raised against human placental type IV collagen and were shown by immunoblotting and ELISA tests to react exclusively with type IV collagen determinants. Extensive immunohistochemical survey studies on panels of tissues from various species, using unfixed cryostat sections, demonstrated that antibody 1042 reacted only with human type IV collagen whereas antibody 1043 in addition reacted with rabbit type IV collagen. All tissues showed homogeneous staining of the basement membrane, indicating that the detected epitopes did not show organ-specific distribution. Tissue processing protocols for using these monoclonal antibodies on routinely processed paraffin embedded tissues were developed. It was found that whereas polyclonal anti-type IV collage antisera required pepsin digestion, our monoclonal antibodies required pronase or papain digestion to restore type IV collagen immunoreactivity in paraffin sections. It is concluded that these monoclonal anti-type IV collagen antibodies detect species specific epitopes which can be detected in routinely processed paraffin embedded tissues after appropriate enzyme pretreatment.

Animals↗