PubMed Health⌕ Search

Biomedical subjects

C P Redfern

Publications and source records attributed to C P Redfern.

At least 55 records · Page 3Linked to original sources
PubMed1992

Characterization of human purified epithelial and stromal cells from endometrium and endometriosis in tissue culture.

OBJECTIVE: To initiate in vitro cultures of separate stromal and epithelial elements from endometriotic tissue and to compare the characteristics of these cells with those of cultured endometrial cells. DESIGN: The study involved testing the viability of a culture system for endometriotic tissue and examination of the phenotype of the cells. SETTING: Fresh tissue samples were collected from the operating theater and transferred to the tissue culture laboratory. PATIENTS, PARTICIPANTS: Twenty patients undergoing laparotomy for endometriosis and patients undergoing surgery for benign conditions were recruited. INTERVENTIONS: Endometrium and endometriotic tissue were separated, cultured in vitro, and labeled by indirect immunofluorescence with monoclonal antibodies against cytoskeletal components and epithelial mucins. MAIN OUTCOME MEASURES: Endometriotic cells have been maintained in vitro and found to resemble endometrial cells closely. RESULTS: With respect to the staining patterns for cytokeratins 18 and 19, vimentin, and three different epithelial mucins, cultured cells from both endometrium and endometriotic tissue had similar properties. Cytokeratins were located in epithelial cells, and vimentin was expressed in both stromal and epithelial cells. The antimucin antibodies all gave distinct patterns of intracellular staining of epithelial cells. CONCLUSIONS: Our results indicate a close similarity between cultured stromal and epithelial cells from endometrium and endometriotic deposits. Culture of these cell populations will permit study of their properties and interactions and may provide some insight into the cause of endometriosis.

Antigens, Neoplasm↗
PubMed1992

The expression of retinoic acid receptors in cultured human endometrial stromal cells and effects of retinoic acid.

Patterns of expression of retinoic acid receptors (RAR) in cultures of human endometrial stromal cells are described. Transcripts for all three classes of RAR were expressed in these cells but RAR-beta was expressed at a low level by comparison with RAR-alpha and RAR-gamma. The abundance of RAR-beta transcripts was elevated by treating the cells with retinoic acid, but there was no effect on the level of expression of RAR-alpha and RAR-gamma. The induction of RAR-beta by retinoic acid was detectable within 4 h and at low concentrations of retinoic acid (10(-10) M). Adenosine 3':5'-cyclic monophosphate (cAMP) analogues and forskolin, an adenylate cyclase activator, had no effect on the retinoic acid-mediated induction of RAR-beta, contrary to recent observations on embryonal carcinoma cells. However, the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine (IBMX), forskolin and 8-bromo-cAMP depressed basal levels of RAR-beta expression. These data suggest that endometrial stromal cells may be a target tissue of retinoic acid in vivo, and imply a role for retinoic acid in the cyclical differentiation of human endometrium.

Blotting, Northern↗
PubMed1992

Retinoic acid receptor expression in human skin keratinocytes and dermal fibroblasts in vitro.

Retinoic acid is essential for the normal differentiation of epithelia but its cellular function is obscure. The expression patterns of retinoic acid receptors (RARs) in skin cell types may give an insight into the role of retinoic acid in skin. We have compared the patterns of RAR expression in human keratinocytes and dermal fibroblasts in vitro, and studied the effects of retinoic acid on RAR expression. RAR-alpha and RAR-gamma were expressed in keratinocytes and fibroblasts: RAR-gamma was expressed at similar levels in both cell types but RAR-alpha was more abundant in fibroblasts. There were no differences in expression of either RAR-alpha or RAR-gamma between stratifying (high-calcium medium) and proliferating (low-calcium medium) keratinocytes and expression of these RARs was unaffected by retinoic acid. RAR-beta was undetectable in keratinocytes. In the majority of fibroblast cell lines, RAR-beta transcripts were either undetectable or expressed at a low level. Retinoic acid at low concentrations (10(-10) to 10(-9) M) rapidly induced the expression of RAR-beta. Cyclic adenosine monophosphate (cAMP) analogues inhibit RAR-beta induction in teratocarcinoma cells. However, dibutyryl-cAMP did not affect RAR-beta induction in fibroblasts. Forskolin, an adenylate cyclase activator, and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) decreased constitutive RAR-beta mRNA levels but did not block induction of RAR-beta by retinoic acid. Since intracellular cAMP levels were only increased detectably in response to forskolin, the reduction in constitutive levels of RAR-beta mRNA may be mediated by mechanisms other than via cAMP.

Carrier Proteins↗
PubMed1990

The biological activity of retinoids in melanoma cells. Induction of expression of retinoic acid receptor-beta by retinoic acid in S91 melanoma cells.

The expression of mRNA for retinoic acid receptor beta (RAR-beta) was induced by all trans-retinoic acid in murine S91 melanoma cells. The induction of RAR-beta was dose-dependent, rapid and insensitive to cycloheximide. Both 13-cis-retinoic acid and 3,4-didehydro-all trans-retinoic acid also induced expression of RAR-beta but were only effective at concentrations 100-fold greater than all trans-retinoic acid. The expression of RAR-alpha and RAR-gamma was unaffected by retinoic acid.

Animals↗
PubMed1989

Differential expression of the alpha and beta retinoic acid receptors in tissues of the rat.

We have compared the expression of alpha and beta retinoic acid receptors (RAR-alpha and RAR-beta) in different rat tissues. The two cDNA probes for RAR-alpha and RAR-beta each specifically detect two different transcripts. RAR-alpha was expressed in all tissues examined, but, in contrast, the expression of RAR-beta was undetectable in some tissues. The data do not support the idea that RAR-beta is specific to epithelial tissues.

Animals↗
PubMed1989

Expression of the alpha and beta retinoic acid receptors in skin.

Retinoic acid receptor (RAR) -alpha and -beta transcripts are expressed in rat and human skin, and in rat and human dermal fibroblasts and keratinocytes in vitro. RAR-alpha transcripts (ca. 2.8 and 3.6 kb) were expressed in all tissues but were more abundant in dermis and dermal fibroblasts than in epidermis or keratinocytes. RAR-beta mRNA was expressed in skin, but patterns of expression differed between human and neonatal rat samples. In human dermal fibroblasts, keratinocytes and whole skin, two RAR-beta transcripts (ca. 3.1 and 3.4 kb) were expressed. Conversely, in neonatal rat skin, dermal fibroblasts, and keratinocytes only the smaller transcript was detectable and was more abundant in cultured cells than in whole tissue. These results suggest that retinoic acid may have complex, as yet undefined, RAR-mediated regulatory functions in both dermis and epidermis.

Animals↗
PubMed1989

Nuclear retinoic-acid-binding proteins and receptors in retinoic-acid-responsive cell lines.

Nuclear retinoic-acid-binding activity and the expression of retinoic acid receptor mRNA (RAR-alpha and RAR-beta) were assayed in the F9 embryonal carcinoma, HeLa, HL-60 promyelocytic leukaemia and S91 melanoma cell lines. A 4-svedberg nuclear retinoic-acid-binding activity was detected in all 4 cell lines, but the levels in the HeLa and HL-60 cells were lower than in the F9 and S91 lines. RAR-alpha mRNA was expressed in all 4 cell lines, although at a very low level in S91 cells. Conversely, RAR-beta mRNA was expressed in S91 cells and, at a lower level, in F9 cells but was undetectable in HeLa and HL-60 cells. RAR-beta, transcribed and translated in vitro from the cloned cDNA coding region, sedimented at 4 S and this suggests that the 4-svedberg nuclear retinoic-acid-binding activity may represent the retinoic acid receptors.

Blotting, Northern↗
PubMed1989

Immunohistochemical markers of human sebaceous gland differentiation.

Cryostat sections of human skin were stained with monoclonal antibodies to involucrin, a range of cytokeratins, epithelial membrane antigen (EMA), and an ovarian cystadenocarcinoma antibody (OM1) to identify combinations of antibodies that could be used to discriminate between basal and differentiated sebocytes and other cell types present in the pilosebaceous unit. Both the EMA and OM1 monoclonal antibodies specifically recognized differentiated sebocytes. No staining of basal sebocytes or other epidermal cell types was seen. Differentiated (but not basal) sebocytes were also stained by a cytokeratin 10 antibody (LH2). Conversely, the basal sebocytes were recognized by an antibody specific to basal keratinocytes (LH6). Cells of the sebaceous duct stained with both LH2 and LH6 and also with the anti-involucrin monoclonal antibody. Cytokeratin 4 has been detected in sebaceous glands by protein analysis but has not previously been detectable immunohistochemically. We show by immunofluorescence after limited proteolysis that cytokeratin 4 epitopes are distributed in all sebaceous gland cells, including the duct cells.

Antibodies, Monoclonal↗
PubMed1988

Purification and properties of cellular retinoic acid-binding protein from neonatal rat skin.

Cellular retinoic acid-binding protein (CRABP) was detected in cytosolic extracts of dermis and epidermis of neonatal rat skin using high-performance size-exclusion liquid chromatography and was more abundant in dermal tissue. CRABP was purified 1000-fold from an acid-precipitated, 50,000 x g supernatant of neonatal rat skin by ion-exchange chromatography on DEAE-Sephacel, followed by chromatofocussing and hydrophobic-interaction chromatography. The protein had an apparent Mr of 14,800. In chromatofocussing experiments the apoprotein and holoprotein gave different elution profiles, indicating a charge difference between the two forms. The ability of various retinoids to compete with all-trans-retinoic acid for binding to CRABP was assayed: 4-oxoretinoic acid and two synthetic retinoids were effective competitors, but 13-cis-retinoic acid, 3,4-didehydroretinoic acid and the acid derivative of etretinate competed poorly. The binding protein had a Kd for all-trans-retinoic acid of 8 nM using a dextran-charcoal assay, but a higher value was obtained using high-performance size-exclusion liquid chromatography. The holoprotein dissociated rapidly at room temperature and had a half-life of 4.7 min. At 0 degrees C, the holoprotein had a half-life of 200 min.

Animals↗
PubMed1988

The effects of retinoic acid on rat epidermal cells in vitro: changes in patterns of protein phosphorylation in relation to growth and differentiation.

Keratinocytes proliferate, stratify, and differentiate in vitro but if the calcium concentration of the medium is reduced to 0.07 mM Ca2+ (low calcium medium) the cells proliferate but do not stratify or differentiate. Keratinocytes proliferating in low calcium medium synthesized DNA at a higher rate than cultures of stratifying keratinocytes and this correlated with increased phosphorylation of a membrane-associated Mr 23,200 phosphoprotein (pp23) relative to cytosolic phosphoproteins of Mr 26,500 (pp27a and pp27b). In both normal and low calcium medium, all-trans-retinoic acid increased phosphorylation of pp23 relative to that of pp27 and increased DNA synthesis after 12-24 h. These results suggest that the phosphoproteins pp23 and pp27 are cell-cycle regulated and that the changes in phosphorylation were a consequence of a stimulation of cell proliferation by retinoic acid. The half-life of all-trans-retinoic acid in these cultures was about 6 h; increased DNA synthesis and concomitant changes in phosphorylation patterns also resulted from a 6-h pulse of retinoic acid followed by an 18-h washout period.

Animals↗
PubMed1987

Characterisation of a retinoic-acid-binding component from F9 embryonal-carcinoma-cell nuclei.

When F9 murine-embryonal-carcinoma cells were incubated with all-trans-[3H]retinoic acid, approximately 10% of the tritium label taken up by the cells was recovered in the nuclei. Sonication or DNase I digestion followed by extraction with 0.6 M NaCl released 20-40% of the nuclear-associated retinoic acid. Analysis of these extracts showed that retinoic acid was bound to protein sedimenting at 4 S. This nuclear retinoic-acid-binding component bound all-trans- and 13-cis-retinoic acid with comparable affinity whereas retinol competed less efficiently for binding. These results suggest that F9 embryonal-carcinoma cells contain a nuclear binding protein for retinoic acid that is distinct from the cellular retinoic-acid-binding protein.

Animals↗
PubMed1984

Evidence for the presence of makisterone A in Drosophila larvae and the secretion of 20-deoxymakisterone A by the ring gland.

Ring glands or brain-ring gland complexes from third-instar Drosophila melanogaster larvae secreted ecdysone [(22R)-2beta,3beta,14alpha,22,25-pentahydroxy-5beta-cholest-7-en-6-one] and two less polar ecdysteroids (LP1 and LP2) in vitro. Radioimmunoassay with different antisera indicated that LP1 and LP2 are side-chain-modified analogues of ecdysone. In high-performance liquid chromatography, the retention time of LP2 was equivalent to that of a precursor of makisterone A [(20R,22R)-2beta,3beta,14alpha,20,22,25-hexahydroxy-24-methyl-5beta-cholest-7-en-6-one] secreted by Dysdercus fasciatus prothoracic glands in vitro. LP2 was metabolized in vitro by the fat body of Drosophila larvae to a product with the characteristics of makisterone A when analyzed by gas chromatography/mass spectrometry (selected ion monitoring). Evidence was obtained for the presence of makisterone A in Drosophila larvae. These data suggest that LP2 is 20-deoxymakisterone A (24-methylecdysone) and that makisterone A could function as an additional moulting hormone in Drosophila, although 20-deoxymakisterone A production is apparently dependent on the sterol composition of the diet. LP1 has not been identified.

Journal Article↗