Search PubMed⌕ Search

Biomedical subjects

F Chytil

Publications and source records attributed to F Chytil.

At least 91 records · Page 5Linked to original sources
PubMed1980

Water-soluble, dextran-linked retinal: preparation, vitamin A-like activity in rats, and effects on melanoma cells.

A new, water-soluble, polymer-linked form of retinal was synthesized and tested for its ability to support the growth of vitamin A-deficient noninbred Holtzman rats and to inhibit the proliferation of melanoma cells in culture. Retinal was conjugated to the hydrazide of carboxymethyldextran in the presence of alpha-and beta-cyclodextrins. The aqueous solutions of the product contained between 200 and 1,000 micrograms retinal/ml as opposed to the low water solubility (< 0.01 micrograms/ml) of retinal itself. The retinal-dextran complex, although barely resorbed from the gastrointestinal tract, supported the growth of rats fed a vitamin A-deficient diet when administered ip at 2.3 mumol of retinal equivalent/kg body weight. Retinal and the retinal-dextran complex exhibited differential cytotoxicity toward S91 melanoma cells and caused cell lysis at 10 and 500 microM (retinal residue), respectively. At noncytotoxic doses both free retinal and its dextran-linked derivative reduced the cell proliferation rate in a time- and dose-dependent fashion with median inhibitory doses of 1 and 4 microM (retinal residue), respectively. These data demonstrated that the water-soluble retinal-dextran complex retained certain biologic activities of retinal and was less cytotoxic.

Animals↗
PubMed1980

Comparison of the level of cellular retinoid-binding proteins and susceptibility to retinoid-induced growth inhibition of various neoplastic cell lines.

The presence and level of cellular retinol-binding protein (CRBP) and cellular retinoic acid-binding protein (CRABP) were determined in several neoplastic cell lines. These cells exhibited different degrees of susceptibility to growth inhibition in culture by two retinoids, retinyl acetate and retinoic acid. CRABP was detected in 10 and CRBP in 3 of the 11 tested cell lines. The levels of CRBP and CRABP were in the ranges 15-3,400 and 4-1,290 pmol per 10(9) cells, respectively, as determined by sucrose gradient centrifugation. Cell lines that contained CRABP included S91 and B16 melanomas; Mm5mT and DMBA No. 8 mammary adenocarcinomas; BW5147, BW5147.RicR, and P3 neoplastic lymphoid cells; F361.2 (a hybrid cell line obtained by fusion of MSV3T3 and BW5147); MSV3T3 sarcoma; and RAW8 lymphosarcoma. All but the last two cell lines were inhibited by retinoic acid in culture. CRBP was detected in extracts of S91, Mm5mT, and RAW8. Retinyl acetate inhibited the growth of all cell lines with the exception of RAW8, MSV3T3, and F361.2. No correlation was found between the level of either binding protein and the extent of growth inhibition by either retinyl acetate or retinoic acid. Neither of the binding proteins was detected in L1210-A5 leukemia cells, whose proliferation can be inhibited by both retinyl acetate and retinoic acid. These data indicated that screening cell lines for the presence and level of CRBP and CRABP is not sufficient to predict the susceptibility of cultured cells to growth inhibition by retinoids.

Adenocarcinoma↗
PubMed1979

Immunochemical comparison of vitamin A binding proteins of rat.

Specific antibodies against cellular retinol-binding protein (CRBP), raised in rabbit, were detected by sucrose gradient centrifugation and gel filtration using tritium-labeled CRBP, prepared by reductive methylation. By means of radioimmunoassay, pure CRBP from liver and testis as well as CRBP present in a crude extract of liver were compared. All preparations showed identical immunoreactivity, suggesting CRBP is not tissue-specific. In contrast, two other vitamin A-binding proteins, cellular retinoic acid-binding protein, and serum retinol-binding protein, showed no cross-reaction in the radioimmunoassay.

Animals↗
PubMed1979

Cellular retinol-binding protein allows specific interaction of retinol with the nucleus in vitro.

Purified cellular retinol-binding protein (CRBP), a potential mediator of vitamin A action, was found to enable retinol to bind in a specific manner to isolated nuclei from livers of vitamin A deficient rats. Binding was followed after complexing [3H]retinol with CRBP. The binding was specific, saturable, and temperature dependent. CRBP charged with unlabeled retinol or CRBP without retinol diminished binding of radioactivity whereas free retinol did not. No specific binding sites could be detected for free retinol. Purified cellular retinoic acid binding protein (CRABI) complexed with retinoic acid did not diminish the amount of retinol bound to nuclei. Approximately 3 x 10(5) specific binding sites per nucleus could be detected. Fewer binding sites were found in nuclei isolated from livers of control (chow-fed) rats and also from livers of vitamin A-deficient rats 2 hr after refeeding with retinylacetate.

Animals↗
PubMed1979

Cellular retinol- and retinoic acid-binding proteins in vitamin A action.

Two intracellular proteins that bind compounds with vitamin A activity have been discovered in animal tissues. One, called cellular retinol-binding protein (CRBP), binds retinol with high specificity and affinity, but not retinal or retinoic acid. The other protein, called cellular retinoic acid-binding protein (CRABP), has high affinity for retinoic acid but does not bind retinol or retinal. CRBP is different from the well-known serum retinol binding protein. The proteins are present in many fetal tissues, whereas their tissue distribution in the adult rat differs. The levels of these proteins change differently during perinatal development, suggesting that they are regulated in a nonsynchronous manner. Some malignant tumors contain these proteins. The presence of these proteins could be an indication of whether the tumor might be inhibited by or might require vitamin A for growth. It appears that the cell nucleus is a target for retinol action, as CRBP allows specific interaction of retinol with the nucleus, showing the presence of specific binding sites for retinol. The number of these sites is dependent on the vitamin A status of the animal.

Animals↗
PubMed1978

Cellular retinoic acid-binding protein from rat testis. Purification and characterization.

Cellular retinoic acid-binding protein has been purified to homogeneity from rat testes. The procedures utilized in the purification included acid precipitation, gel filtration, and chromatography on DEAE-cellulose. The binding protein was purified approximately 12,000-fold, based on total soluble testicular protein. The protein is a single polypeptide chain with a molecular weight of 14,600, determined by information from gel filtration and sodium dodecyl sulfate-polyacrylamide electrophoresis. The protein binds retinoic acid with high affinity; the apparent dissociation constant was determined by fluorometric titration to be 4.2 X 10(-9) M.

Animals↗
PubMed1978

Cellular retinol-binding protein from rat liver. Purification and characterization.

Cellular retinol-binding protein has been purified to homogeneity from rat liver. The procedures utilized in the purification included acid precipitation, gel filtration on Sephadex G-75 and G-50, and chromatography on DEAE-cellulose. The binding protein was purified approximately 3,500-fold, based on total soluble liver protein. The protein is a single polypeptide chain with a molecular weight of 14,600 based on information obtained by the techniques of sedimentation equilibrium analysis, gel filtration, and sodium dodecyl sulfate-polyacrylamide electrophoresis. The protein binds retinol with high affinity; the appparent dissociation constant was determined by fluorometric titration to be 1.6 X 10(-8) M. Retinol bound to the protein has an absorption spectrum (lambdamax, 350 nm) considerably altered from the spectrum of retinol in ethanol (lambdamax, 325 nm).

Animals↗
PubMed1978

Human granulocyte specific nuclear antigen(s). I: Production of antisera and determination of specificity.

Non-histone protein-DNA complexes isolated from human lung tissue were used to immunize New Zealand rabbits. Quantitative microcomplement fixation and immunocytochemistry revealed a specific chromatin antigen(s) in the human granulocyte nucleus. The study demonstrates the feasibility of employing antisera against chromosomal non-histone protein-DNA complexes for the immunochemical identification of cell types.

Animals↗
PubMed1978

Effect of low lysine diet on rat liver nuclear metabolism.

Prolonged dietary lysine deficiency induced by feeding male weanling rats a diet low in lysine for 6 weeks resulted in substantial impairment of growth as compared with control rats and in alterations in the morphology of the nucleus of hepatocytes. Electronmicrographs of liver nuclei from lysine deficient rats showed an increased incidence of binucleated cells, reduction in numbers of nucleoli, changes in the position and size of nucleoli within the nucleus and altered patterns of chromatin aggregation in lysine deficient rats. Mass ratios of nonhistone proteins to DNA in liver chromatin from lysine deficient rats were higher than those of controls and electrophoretic patterns of chromatin nonhistone proteins were altered. In particular, one high molecular weight fraction of these proteins showing the same mobility as myosin was substantially enriched. The histone: DNA ratio and histone electrophoretic patterns, however, appeared to be unchanged. Incorporation of [3H] thymidine into DNA was increased, but the nuclear content of DNA was unchanged in lysine deficient animals.

Animals↗
PubMed1978

Effect of low lysine diet on rat protein metabolism.

Prolonged lysine deficiency resulted in inhibition of growth of the rat and in lowered levels of albumin and beta-globulins, but not of total liver proteins. The apparent incorporation of [3H]lysine into total and chromosomal liver proteins, however, was increased in lysine deficient rats relative to pair-fed controls. The concentration of free lysine in neither serum nor liver was altered in lysine deficient rats. The specific radioactivity of liver free lysine 2 hours after administration of [3H]lysine was noticeably elevated in the deficient rats. However, when the pool of liver free lysine is considered, synthesis of all proteins studied was inhibited. The largest inhibitory effect was seen in serum albumin and total liver protein synthesis. Inhibition of snythesis of nuclear chromatin protein was less pronounced. The data indicate an adaptive mechanism operates to preserve liver lysine in rats fed lysine deficient diets for a prolonged period. In spite of retention of lysine, the synthesis of liver and serum proteins was inhibited.

Adaptation, Biological↗
PubMed1977

Tissue-specific antibodies against human lung and breast carcinoma dehistonized chromatins.

Tissue-specific antisera against human lung and breast carcinoma dehistonized chromatins were obtained. The specificity of these antisera was determined by complement fixation. In the presence of antiserum against human lung carcinoma, only chromatins from lung carcinoma fixed complement significantly, whereas chromatins isolated from human breast carcinoma, HeLa cells, normal lung tissue, breast tissue, or term placenta were negative (i.e., inactive). In a similar assay with the use of antiserum against dehistonized breast carcinoma chromatins, only breast carcinoma chromatins fixed complement. Immunohistochemical localization of the antigens by the horseradish peroxidase bridge method demonstrated their presence in the nuclei.

Animals↗
PubMed1976

Presence of cellular rentinol and retinoic acid binding proteins in experimental rumors.

Cellular retinol and retinoic acid binding proteins were detected in mouse skin papillomas, human adenocarcinoma HAD-1, Dunning Leukemia, Walker 256 carcinosarcoma and mammary adenocarcinoma MAC-1. A chondrosarcoma and Sarcoma 180 apparently contain only the cellular retinoic acid binding protein. Neither protein could be detected in Ehrlich carcinoma and L1210 leukemia. The presence of these proteins might be necessary for sensitivity to retinoid therapy.

Animals↗