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Biomedical subjects

F Chytil

Publications and source records attributed to F Chytil.

At least 73 records · Page 4Linked to original sources
PubMed1984

Immunocytochemical localization of cellular retinol binding protein in the rat retina.

Cellular retinol binding protein (CRBP) was localized in the rat retina by means of light and electron microscopic immunocytochemistry. The peroxidase-antiperoxidase (PAP) method employed at the light microscopic level showed that CRBP is sharply localized to the retinal pigment epithelium (RPE). None was detectable in the epithelium of the pars plana or pars plicata of the ciliary body. Likewise, the photoreceptors were negative. Within the neural retina, the PAP method revealed a bilaminar staining pattern in the inner plexiform layer and staining within elements near the vitreal surface. Indirect immunoferritin electron microscopy demonstrated that CRBP is distributed uniformly within the RPE cytosol from basal infoldings to apical processes. The nucleoplasm also was stained, albeit, more lightly than the cytoplasm. Labeled elements in the inner plexiform layer and vitreal surface were identified as Müller cell processes and end feet, respectively. Interpretation of the results includes a dual role for CRBP in the RPE, namely its involvement in gene expression and transcytoplasmic transport of retinol.

Animals↗
PubMed1983

Localization of cellular retinol-binding protein in several rat tissues.

The distribution of cellular retinol-binding protein (CRBP) in rat liver, ileum, and epididymis was examined by the peroxidase-antiperoxidase immunolocalization technique. Positive cytoplasmic staining was seen in the liver when antiserum prepared against purified CRBP was used but not when antiserum absorbed with purified CRBP was used. Ileal mucosa, a tissue that contains no detectable CRBP, showed no positive staining. The epididymis showed strong positive staining in the caput but not in the cauda. Staining was present in principal and basal cells but not in peritubular or interstitial cells. Radioimmunoassay revealed that the CRBP within the caput epididymidis was localized in the initial segment and proximal region, areas known to be involved in the synthesis and secretion of factors necessary for sperm maturation. The results demonstrate that the expression of CRBP may vary within the same cell type, as well as between different cell types within the same tissue.

Animals↗
PubMed1982

Radioimmunochemical determination of cellular retinol- and cellular retinoic acid-binding proteins in cytosols of rat tissues.

Radioimmunoassays have been developed for cellular retinol-binding protein and cellular retinoic acid-binding protein, postulated mediators of vitamin A action in nonvisual functions. These assays are considerably more sensitive for detection and quantitation of these proteins than previous methods. The higher sensitivity has permitted the detection of cellular retinoic acid-binding protein in adult rat tissues previously considered negative. These include kidney, lung, and spleen. The only tissues negative for both binding proteins were adrenals, skeletal muscle, ileal mucosa, and serum. Assay of tissue levels of cellular retinol-binding protein and cellular retinoic acid-binding protein reveals them to be widely distributed throughout most organs of the rat. No tissue or sex differences in these proteins were detected in these studies.

Animals↗
PubMed1982

Retinopathy following jejunoileal bypass surgery: report of a case.

Vitamin A deficiency associated with retinopathy and night blindness was observed in a patient 4 yr after jejunoileal bypass. Upon further investigation, a multiple vitamin deficiency state was established. Daily supplementation with 30 000 units of vitamin A resulted in normal levels of vitamin A and retinol-binding protein. The patient's night blindness improved, but his retinopathy remained unchanged as demonstrated by fluorescein angiography. We conclude that patients who have undergone jejunoileal bypass should be supplemented with vitamin A since the vitamin A deficiency is preventable and the retinopathy associated with the deficiency may not be totally reversible.

Adult↗
PubMed1981

Interaction of the retinol/cellular retinol-binding protein complex with isolated nuclei and nuclear components.

Retinol (vitamin A alcohol) is involved in the proper differentiation of epithelia. The mechanism of this involvement is unknown. We have previously reported that purified cellular retinol-binding (CRBP) will mediate specific binding of retinol to nuclei isolated from rat liver. We now report that pure CRBP delivers retinol to the specific nuclear binding sites without itself remaining bound. Triton X-100-treated nuclei retain the majority of these binding sites. CRBP is also capable of delivering retinol specifically to isolated chromatin with no apparent loss of binding sites, as compared to whole nuclei. CRBP again does not remain bound after transferring retinol to the chromatin binding sites. When isolated nuclei are incubated with [3H]retinol-CRBP, sectioned, and autoradiographed, specifically bound retinol is found distributed throughout the nuclei. Thus, CRBP delivers retinol to the interior of the nucleus, to specific binding sites which are primarily, if not solely, on the chromatin. The binding of retinol to these sites may affect gene expression.

Animals↗
PubMed1981

Cellular retinol binding protein during postanal development of the rat small intestine.

Levels of the cellular retinol-binding protein (CRBP) were measured in extracts of rat small intestine from 1 day before birth to day 21 postnatally. Changes in the amount of CRBP per cell were observed. The highest levels were observed in the 1-day-old rat. The amount of CRBP gradually declined until the animals reached the age of 21 days. Thereafter only a slight decline was observed. The postnatal development of CRBP was similar in the jejunum and the ileum, with the jejunum always showing higher levels. However, CRBP was detectable in the jejunum but not in the ileum of adult rats.

Animals↗
PubMed1981

Autoradiographic localization of serum retinol-binding protein in rat testis.

An interstitial target site in the rat testis for vitamin A has been detected using radioactively labeled rretinol-binding protein (RBP) in autoradiography at the light microscope level. RBP purified from rat serum was iodinated by the lactoperoxidase procedure and was also complexes with [3H]-retinol. The radioactively labeled RBP was administered to rat testis tissue by a direct intratesticular injection, an iv injection, and through an in vitro incubation of decapsulated tissue in medium containing the labeled protein. Localization on the autoradiograms of both [125I]RBP and [3H]retinol-RBP was interstitial; there was no interaction of RBP with cells in or on the seminiferous tubules. The patterns of localization were identical in normal rats and vitamin A-deficient rats. [3H]etinol uncomplexed with RBP (administered with rat serum albumin) was distributed evenly throughout testicular tissue, with no specific localization. Although the labeling of the cells on the autoradiograms was not visible diminished by the presence of excess unlabeled RBP, an in vitro binding assay of a crude interstitial cell preparation using [125I]RBP displayed saturable binding, indicative of receptors for RBP. An in vitro binding assay of Sertoli cells in culture with [125I]RBP demonstrated no specific binding, nor did [125I]RBP in autoradiography of Sertoli cell monolayers display interaction with these cells. Results from this investigation show that the plasma transport protein for vitamin A, RBP, interacts initially with cells in the interstitium of the testis. (Endocrinology 108: 658, 1981)

Animals↗
PubMed1981

Evidence of a role for retinoic acid (vitamin A-acid) in the maintenance of testosterone production in male rats.

Animals maintained on retinol (vitamin A-alcohol)-deficient diets exhibit testicular atrophy and loss of the germinal epithelium. Retinoic acid (vitamin A-acid), when fed to retinol-deficient animals, does not prevent these lesions and had thus been thought not to play a role in the tests. Serum testosterone (T) levels, determined by RIA, in retinol-deficient rats were determined to be significantly lower than in control rats. In contrast, retinoic acid-fed, retinol-deficient rats exhibited serum T concentrations similar to those of control rats. No difference in immunoreactive serum LH levels was observed in the three groups. The response of serum T to ip administration of LH in retinol-deficient animals relative to basal levels was similar to that observed in control as well as retinoic acid-fed, retinol-deficient rats. These results show that while basal T production in retinol-depleted rats is decreased, LH-stimulated T synthesis is unaffected. Furthermore, retinoic acid, in the absence of retinol, can support T production, suggesting that contrary to present dogma, retinoic acid plays a role in testis.

Animals↗
PubMed1980

Three-step purification of retinol-binding protein from rat serum.

Rat serum retinol-binding protein has been purified to apparent homogeneity in high yield by a new procedure utilizing three simple steps: DEAE-cellulose chromatography at pH 6.0, Sephadex G-75 gel filtration in the presence of 3.0 M urea, and finally DEAE-cellulose chromatography at pH 8.3. The second step accomplished the dissociation and separation of retinol-binding protein from its complex with prealbumin; this represents a substantial improvement over published procedures, in which sample recycling and preparative polyacrylamide gel electrophoresis were necessary. The purified retinol-binding protein was characterized by molecular weight measurement, fluorescence spectra and immunological properties.

Animals↗