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Biomedical subjects

C F Shuler

Publications and source records attributed to C F Shuler.

At least 19 recordsLinked to original sources
PubMed1992

Medial edge epithelium fate traced by cell lineage analysis during epithelial-mesenchymal transformation in vivo.

Vital cell labeling techniques were used to trace the fate of the medial edge epithelial (MEE) cells during palatal fusion in vivo. Mouse palatal tissues were labeled in utero with DiI. The fetuses continued to develop in utero and tissues of the secondary palate were examined at several later stages of palatal ontogeny. The presence and distribution of DiI was correlated with the presence of cell phenotype-specific markers. During the initial stages of palatal fusion the DiI-labeled MEE were present in the midline position. These cells were attached to an intact laminin-containing basement membrane and contained keratin intermediate filaments. At later stages of palatogenesis the DiI-labeled MEE were not separated from the mesenchyme by an intact basement membrane and did not contain keratin. In late fetal development, DiI-labeled cells without an epithelial morphology were present in the mesenchyme. The transition of the DiI-labeled cells from an epithelial phenotype to a mesenchymal phenotype is consistent with a fate of epithelial-mesenchymal transformation rather than programmed cell death.

Animals↗
PubMed1991

Histopathologic comparison between human oral squamous cell carcinomas and their xenografts in nude mice.

Tumor portions were obtained from 11 oral squamous cell carcinomas and used to produce tumors in a xenogeneic gnotobiotic nude mouse model system. The tumors that developed were examined histologically. The cellular features and tumor growth patterns were compared between the original oral squamous cell carcinoma (T0) and the tumor that developed in the xenogeneic host (T1). The T1 tumors were more highly differentiated in comparison with the T0 tumors. The T1 tumors exhibited less cellular pleomorphism and a more uniform pattern of stratification. The cells in the T1 tumors exhibited an increased mitotic index but did not contain abnormal mitoses. The T1 tumors usually exhibited nodular growth patterns rather than the infiltrating pattern exhibited by the parenchyma of the T0 tumors. The desmoplastic reaction was markedly reduced in the T1 tumors. The results indicated that the gnotobiotic nude mouse model system either selects for or induces a more differentiated pattern of tumor growth than that found in the original human oral squamous cell carcinomas.

Adult↗
PubMed1991

Ultrastructural characteristics of a cell line derived from a melanotic neuroectodermal tumor of infancy.

Thin section and freeze-fracture transmission electron microscopy were used to examine and identify the cytoplasmic and membrane structures in a cell line derived from a melanotic neuroectodermal tumor of infancy (MNTI). The cultured cells had a uniform appearance after 70 population doublings characterized by long dendritic processes and evidence of melanin production. The cytoplasm contained numerous melanosomes in various stages of development, vesiculated rough endoplasmic reticulum, microfilaments and uncoated as well as coated vesicles. The membrane specializations included caveoli, coated pits, gap junctions, microfilaments, desmosome-like structures and lamellipodia. The ultrastructural appearance of the cultured MNTI cells was similar to features previously seen in electron micrographs of MNTI tumor specimens. However, correlated freeze-fracture and thin section micrographs permitted further identification of structures previously described. The MNTI cell line represents one of the cell types of the tumor and provides an opportunity for further study of the pathogenesis of this rare tumor.

Cell Line↗
PubMed1991

Molecular and morphologic changes during the epithelial-mesenchymal transformation of palatal shelf medial edge epithelium in vitro.

The fate of the medial edge epithelial (MEE) cells during palatal fusion has been proposed to be either programmed cell death or epithelial-mesenchymal transformation. Vital cell labeling techniques were used to mark the MEE and observe their fate during palatal fusion in vitro. Fetal mouse palatal shelves were labeled with Dil and allowed to proceed through fusion while maintained in an organ culture system. The tissues were examined at several stages of palatal fusion for the distribution of Dil, presence of specific antigens and ultrastructural appearance of the cells. The MEE labeled with Dil occupied a midline position at all stages of palatal fusion. Initially the cells had keratin intermediate filaments and were separated from the underlying mesenchyme by an intact basement membrane. During the process of fusion the basement membrane was degraded and the Dil-labeled MEE were in contact with the mesenchymal-derived extracellular matrix. In the late stages of fusion the Dil-labeled MEE altered their cellular morphology, had vimentin intermediate filaments, and were not associated with an identifiable basement membrane. Dil-labeled cells, without an epithelial phenotype, remained present in the midline of the completely fused palate. The data indicate that the MEE did not die but underwent a phenotypic transformation to viable mesenchymal cell types, which were retained in the palatal mesenchyme.

Animals↗
PubMed1989

Intraoral grafting of a canine full-thickness oral mucosal equivalent produced in vitro.

A canine full-thickness oral mucosal equivalent (FTOME) was produced in vitro and used in intraoral grafting. The FTOME consisted of an autologous stratified epithelial surface layer overlying an acellular bilaminar collagenous matrix. The material was grafted on the periosteum of deepithelialized edentulous alveolar ridges in dogs. Biopsies of the grafted FTOME showed that the epithelium remained viable, migrated over the surrounding tissue, and aided in wound healing.

Alveolar Process↗
PubMed1989

Development of neoplastic phenotype following transfection of HNF cells with sarcoma DNA.

DNA isolated from chondrosarcoma cells effectively transformed NIH-3T3 cells and human foreskin fibroblasts. The transfected NIH-3T3 cells, directly implanted three or four passages later, formed progressively growing tumors (greater than or equal to 2.0 cm in diameter) subcutaneously in nude mice. No metastasis was evident upon pathological examination of the tumor bearing mice. Transfected human foreskin fibroblasts that exhibited anchorage independent growth formed only small tumors in nude mice (less than 0.6 cm in diameter). The transfected human cells which exhibited anchorage independent growth reacted with the monoclonal antibody 345.134S, specific for an epitope expressed by human sarcoma cells. The transfected NIH-3T3 cells did not exhibit reactivity with the same monoclonal antibody. Southern blot analysis of the DNA prepared from the transfected NIH-3T3 cells, that developed as a progressively growing tumor in a nude mouse, revealed the presence of human repetitive DNA sequences.

Animals↗
PubMed1989

Localization of H-ras mRNA in oral squamous cell carcinomas.

Expression of the H-ras oncogene was examined in 5 SCC of the oral cavity. The presence of oncogene mRNA was detected and localized in the tumor tissue by in situ hybridization. Tumor tissues were also examined for the presence of the oncogene product, p21, by immunohistochemical techniques. H-ras mRNA and p21 were detected in all 5 tumors in cells that were also positive for both keratin mRNA and keratin protein. The distribution of the mRNA was not uniform throughout the tumor tissue. Distinct spatial localizations of the H-ras mRNA were present in regions of the tumors with both higher proliferative and invasive potential. The results suggest that the distribution of the oncogene mRNA may be related to the pattern of development and progression of oral SCC.

Aged↗
PubMed1989

Effect of periodontal dressings on human gingiva fibroblasts in vitro.

In vitro cytotoxicity studies of periodontal dressings have not generally produced a result consistent with in vivo observations. These prior in vitro studies have not used human intraoral cell lines. We tested the effects of two eugenol containing and two non-eugenol periodontal dressings on cultured human gingival fibroblasts (HGF) (ATCC #1292). Replicate HGF cultures grown in microtiter plates were exposed to stock, 1:4 and 1:16 dilutions of extracts made from each of the four periodontal dressings. The HGF cultures were pulse labelled with tritiated thymidine (3HTdR) after 24, 48, and 72 hours. Incorporations of the labelled thymidine were measured using liquid scintillation counting and expressed as counts per minute. The results showed that undiluted extracts from all four periodontal dressings totally inhibited 3HTdR uptake (P less than 0.05). The 1:4 dilution of eugenol dressings inhibited 3HTdR uptake significantly more than non-eugenol dressings (P less than 0.05). Interestingly, at 72 hours the 1:16 dilution of the non-eugenol dressings caused significantly increased 3HTdR uptake which was not observed with the eugenol dressings. The present results suggest that the use of a human fibroblastic cell line for testing the effects of periodontal dressings may provide information about the relative biological effects of these dressings. Using this cell line, we have found that eugenol dressings inhibit fibroblast proliferation to a greater extent than non-eugenol dressings.

Cell Line↗
PubMed1988

Transformation of normal homologous cells by a spontaneously activated Ha-ras oncogene.

Several tumor-derived oncogenes have been shown to independently act as complete carcinogens following transfection into target cells from established tissue culture lines. However, the number and types of oncogenes required to transform primary cultures of normal mammalian cells is unclear. To clarify this issue in a simplified model system, we transfected genomic DNA from a naturally occurring rat tumor into NIH/3T3 cells as well as into early passage rat embryo fibroblasts. The 3T3 cells were transformed with high efficiency to malignant phenotypes; the rat embryo cells were transformed at lower frequencies following cotransfection with a selectable neomycin resistance marker and treatment with Geneticin (G418). The transformed rat cells had cancerous phenotypes as determined by in vitro, cytogenetic, and in vivo criteria. Moreover, the transformed mouse and rat cells contained new tumor DNA-derived nucleotide sequences homologous to the activated human Ha-ras oncogene. Elevated levels of Ha-ras-specific mRNA, as well as enhanced expression of the Mr 21,000 oncogene product, were detected in the transformed cells. Therefore, under well-defined experimental conditions, a spontaneously activated Ha-ras oncogene from a naturally occurring tumor was able to independently transform normal, homologous cells to a malignant phenotype.

Animals↗
PubMed1987

Identification of intermediate filament keratin proteins in parakeratinized odontogenic keratocysts. A preliminary study.

The keratin proteins were extracted from the epithelial lining of three odontogenic keratocyst specimens. Two of the specimens were from a patient with nevoid basal cell carcinoma syndrome; the third was a solitary lesion. Seven keratin proteins with molecular weights of 46, 48, 50, 52, 54, 58, and 59 kilodaltons were identified by SDS-polyacrylamide gel electrophoresis and immunoblotting with antikeratin antiserum. The reproducibility of the pattern of molecular markers implies a series of genetic events coincident with the characteristic pattern of epithelial differentiation.

Adult↗
PubMed1987

Keratin protein identification in dimethylbenzanthracene-induced hamster cheek-pouch squamous cell carcinomas.

Individual keratin proteins were identified in 10 DMBA induced squamous cell carcinomas (SCC) of the hamster cheek pouch. SDS-polyacrylamide gel electrophoresis of water-insoluble cytoskeletal extracts from the tumor tissue demonstrated alterations in the protein distribution normal for the site. Immunoblot analysis with a broad spectrum polyclonal antikeratin antiserum identified the keratins in the preparations and confirmed changes in their distribution in the tumor preparations. The major keratin species for all the tumor tissues ranged in molecular weight from 45 to 57kd. The normal tissues had keratins with molecular weights from 45 to 73kd. The absence of high molecular weight keratins was a prominent feature in all the cancers. The histologic appearance of the tumors was varied but the distribution of the keratins was not correlated with the various histologies. The results demonstrate that changes in keratin gene expression occur in DMBA-induced cheek-pouch carcinomas but the precise alterations in the keratin proteins from those seen normally are not predictable.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1986

Studies of androgen metabolism and action in cultured hair and skin cells.

In order to study the mechanism of action of androgen on pubic and scalp hair, we established these and skin epithelial cells in culture. Because 5 alpha-reductase has been suspected of playing a role in hair growth, we tested the possibility that these cells differ in their pattern of androgen metabolism. Furthermore, we tested the hypothesis that androgen exerts its distinctive effects on these hairs by differentially regulating keratin or DNA synthesis. Anagen hairs of men and women were plucked from the pubis or scalp vertex and were studied using an epithelial cell culture technique. DHT formation from [3H]T cultured skin cells increased in the following order: epidermal less than scalp less than pubic less than fibroblasts = 0.8:2.8:8.1:71%/mg DNA/min, respectively. Androstanediols were minor [3H]DHT metabolites of all these skin cell types. The only feature that distinguished among the cultured epithelial cells was the ratio of apparent 5 alpha-reductase (5 alpha-R) to 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity: this was significantly greater (P less than 0.05) in cultured pubic hair cells than in scalp hair or epidermal cells. Cultured scalp and pubic hair cells resembled freshly plucked hair follicle cells in their keratin pattern. 46, 50, 56 and 58 kdalton bands constituted 99% of the total keratins. This keratin pattern and the polygonal cell shape were also similar to that of cultured epidermal cells. However, this keratin pattern was distinctly different from that of hair shafts which have 53 and 63 kdalton keratins. Dihydrotestosterone did not affect the keratin pattern, pattern of incorporation of [35S]cysteine or [35S]methionine, or rates of protein synthesis or cell proliferation in cultured hair cells. Although the higher apparent 5 alpha-R/17 beta-HSD ratio of cultured pubic than of scalp hairs is compatible with modulation of hair development by androgen, these studies militate against the possibility that androgens directly affect hair cell proliferation or protein synthesis in pubic or scalp hair.

17-Hydroxysteroid Dehydrogenases↗
PubMed1986

Embryogenesis of stratified squamous epithelium. I. Tissue-specific expression of keratin proteins.

Although several types of modified stratified squamous epithelia are present in the adult mammal, most are presumably derived from similar embryonic progenitors. Mechanisms responsible for region-specific specialization are poorly understood. To correlate epithelial diversification with the expression of tissue-specific markers, we analyzed keratin protein composition in four representative types of rat squamous epithelia from early embryonic through adult phases of development. Keratin subsets synthesized in palatal mucosa were qualitatively similar, but differed dramatically in relative abundance. Tongue mucosa synthesized a different, but consistent subset of keratins which also changed quantitatively throughout morphogenesis. In contrast, different keratin genes were sequentially expressed during histogenesis of backskin and footpad epidermis. These data indicate that tissue-specific keratin biosynthesis is genetically predetermined early in embryogenesis.

Animals↗
PubMed1986

Embryogenesis of stratified squamous epithelium. II. Developmental stage-specific immunoreactivity of keratins.

Throughout embryogenesis of the rat palate, from the early fetal to adult stages, a consistent subset of keratin proteins is synthesized in the epithelial lining cells. Although the relative abundance of particular keratins has been shown to vary with ongoing palatogenesis, the expression of finite keratins appears to be genetically predetermined. In order to preliminarily ascertain whether conformational changes accompanied intermediate filament 'maturation' from monomeric to polymeric keratin formation, we screened cytokeratins with polyclonal and monoclonal antibodies generated against adult-type keratins. Until epithelial stratification occurred on the 16th day of gestation, the keratin proteins were weakly immunoreactive. On the other hand, subsequent to epithelial thickening, adult-type immunoreactivity was initiated and progressed concomitantly with ongoing palatal development. These findings suggest that the cytokeratin intermediate filaments may progress through conformational 'maturation' during polymerization, and play a role in the eventual acquisition of the adult-type epithelial structure and function.

Animals↗
PubMed1981

In vitro epithelial cell outgrowth from oral leukoplakia.

The appearance of an epithelial cell outgrowth in vitro from biopsies of oral leukoplakia is compared with the histologic appearance of the lesion. Tissue samples from oral leukoplakia of 20 patients were cultured to allow the outgrowth of populations of epithelial cells. Adjacent tissue within the lesions was fixed for routine histology. Epithelial cell outgrowth was successful from biopsies possessing the histologic characteristics hyperkeratosis (14 of 20 cases), altered epithelial thickness (14 of 19 cases) and increased mitotic activity (1 of 4 cases). No epithelial cell outgrowth was observed from leukoplakia tissue possessing signs of epithelial dysplasia (0 of 2 cases).

Cells, Cultured↗