Search PubMed⌕ Search

Biomedical subjects

F Uehara

Publications and source records attributed to F Uehara.

At least 37 records · Page 2Linked to original sources
PubMed1996

Lectin-histochemical study of O-linked glycoconjugates in dysplastic retina of Norrie disease.

The carbohydrate chains of O-linked glycoconjugates in dysplastic retina from a Japanese female infant with Norrie disease were examined by lectin histochemistry. The avidin-biotinylated peroxidase method was used. The retina was highly dysplastic and composed of undifferentiated embryonic tissues containing a number of rosettes of varying sizes. The lumina of the rosettes were stained by peanut agglutinin, which recognizes the Gal beta 1,3GalNAc sequence of O-linked glycans. However, the lumina were not labeled by wheat germ agglutinin, which reacts with sialic acid and/or N-acetylglucosamine. These observations suggest that the O-linked glycoconjugates in the lumina of rosettes were not sialylated in the present case. Their lack of terminal sialic acids may be related to the rosette formation.

Acetylglucosamine↗
PubMed1995

[Beneficial effect of a retinoic acid responsive gene product, midkine, on constant light-induced retinal damage in albino mice].

We studied the protective effects of midkine, a growth factor produced by a retinoic acid responsive gene, on constant light-induced retinal damage in albino BALB/C adult mice. Two days before exposure to constant light, midkine was injected into the vitreous of the left eye and a phosphate buffer saline into the right eye (control eyes). After 7 days of constant light, control eyes exhibited shortening of the photoreceptor outer segments and decreased thickness of the outer nuclear layer, whereas in midkine-treated eyes photoreceptor cells were virtually intact. Although midkine-treated eyes also showed photoreceptor damage after longer light exposure of up to 21 days, the damage was significantly less than in control eyes. Measurement of the thickness of the outer nuclear layer showed the protective effect of intravitreous midkine on the constant light-induced retinal damage. These findings suggest that midkine is a potential agent for the prevention of photoreceptor degeneration.

Albinism, Ocular↗
PubMed1995

Expression of distribution of alpha 2,3-sialyltransferase mRNA in rat cornea.

The glycocalyx, present on the surface of the corneal epithelium, contains sialoglycoconjugates. The developmental change in the sialylated residues may be evaluated by examining the expression of the sialyltransferase mRNA. We examined the distribution of Gal beta 1,3GalNAc alpha 2,3-sialyltransferase mRNA in rat corneas during development using in situ hybridization histochemistry to detect the starting point of the synthesis of O-linked sialoglycoconjugates. Eyelid opening occurred between postnatal days 14 (P14) and 16 (P16). In the corneal epithelium, little hybridization signal was observed until P12, whereas distinct hybridization signals were identified at P14 and thereafter. The expression of alpha 2,3-sialyltransferase mRNA is developmentally regulated, based on the programmed time-course of the gene expression, and the corneal epithelium may start to synthesize O-linked sialoglycoconjugates prior to the critical eyelid opening stage.

Animals↗
PubMed1995

[Binding of amaranthin in human retina].

The binding of amaranthin, specific for Gal beta 1,3 GalNAc and sialic acid Gal beta 1,3 GalNAc sequences, to the human retina was investigated with avidin biotinylated peroxidase. Amaranthin bound to the cone and rod photoreceptors, inner plexiform layer, ganglion cells, and nerve fibers. Since peanut agglutinin, specific for Gal beta 1,3 GalNAc, selectively binds to cones, we conclude that O-glycoside-linked glycoconjugates are present on the surfaces of both cones and rods: Gal beta 1,3 GalNAc and sialic acid Gal beta 1,3 GalNAc are terminal sugars of the glycoconjugates around cones and rods, respectively.

Glycoconjugates↗
PubMed1995

[Distribution of alpha 2,3-sialyltransferase mRNA in rat iris and ciliary body].

The distribution of alpha 2,3-sialyltransferase (alpha 2,3-ST) mRNA in the rat iris and ciliary body was investigated with in situ hybridization histochemistry. Strong expression of alpha 2,3-ST mRNA was detected in the inner epithelial layer of the ciliary body and weak expression in the iris epithelium. Since the synthesis of sialoglycoconjugates is completed by terminal sialylation by the action of sialyltransferase (ST), the ST-expressed portions are considered to produce sialoglycoconjugates. Hence, the source of the sialoglycoconjugates found in the inner epithelial layer of the ciliary body in previous histochemical studies is the same epithelial cell.

Animals↗
PubMed1995

The ultrastructural study of ribosomes in photoreceptor inner segments of the pcd cerebellar mutant mouse.

Ultrastructural changes in the distribution of free ribosomes in photoreceptor inner segments in relation to photoreceptor degeneration in Purkinje cell degeneration (pcd) were studied in mutant mice reared under cyclic light and sacrificed at 30 and 120 postnatal days. On postnatal day 30, some photoreceptors appeared to be normal whereas others had degenerated to varying degrees with numerous spherules in the extracellular space surrounding degenerating inner segments. By postnatal day 120, retinal degeneration had progressed with a marked loss of photoreceptors. The distribution of free ribosomes in the mutant inner segments was random, clustered, or uniform. This was distinct from normal control retinas in which random distribution predominated. Markedly degenerated inner segments contained sparse ribosomes which coalesced in small aggregates. These changes in ribosome distribution seemed to be associated with the extent of photoreceptor degeneration. The significance of these changes in ribosome distribution, in particular clustered distribution, is discussed together with our previous findings.

Animals↗
PubMed1995

Differential expression of mRNA for alpha 2,3-sialyltransferase during development of rat retina.

Glycoconjugates, consisting of O- and N-linked types, are present on the surface of photoreceptor cells and in the interphotoreceptor matrix (IPM). This study was undertaken to facilitate understanding of the metabolic features of O-linked sialoglycoconjugates in comparison with those of N-linked glycoconjugates in the rat retina. We examined the developmental change in distribution of Gal beta 1,3GalNAc alpha 2,3-sialyltransferase mRNA in rat retinas using in situ hybridization histochemistry to detect the synthesis period of O-linked sialoglycans. Positive hybridization signal was observed in the ganglion cells throughout the postnatal days (P) examined, whereas strong signals were detected in the photoreceptor inner segments and the inner nuclear layer exclusively at P16 and P18. At P20 and older, weak or sparse signals were detected in these regions. It is likely that O-linked sialoglycoconjugates, which are detected in the mature IPM, are actively synthesized from P16 to P18 in the rat photoreceptor inner segments, suggesting that the O-linked sialoglycoconjugates in the photoreceptor layer may be stable with litter turnover in the mature retina.

Animals↗
PubMed1994

Binding of amaranthin in photoreceptors of monkey retina.

The binding of amaranthin, specific for the Gal beta 1,3 GalNAc and NeuAc alpha 2,3 Gal beta 1,3 GalNAc sequences, to the photoreceptors of the monkey retina was investigated using the avidin-biotinylated peroxidase method. Amaranthin bound to the surfaces of both cone and rod photoreceptors. This and previous lectin histochemical studies show that O-glycoside-linked glycoconjugates are present on the surfaces of both cones and rods: Gal beta 1,3 GalNAc and NeuAc alpha 2,3 Gal beta 1,3 GalNAc are the terminal sugars of the glycoconjugates around cones and rods, respectively.

Animals↗
PubMed1994

Maackia amurensis lectin binding in developing rat retina.

The developmental changes in the binding of Maackia amurensis lectin, specific for sialic acid alpha 2,3 galactose sequence, to the rat retina was investigated using the avidin-biotinylated peroxidase method. The lectin bound to the surfaces of photoreceptor outer segments from postnatal day 16 (P16), whereas it had bound to the other retinal layers from P14. The intense labelings of the outer segments were interspersed with unstained portions, which may correspond to cone photoreceptors. These results confirm that the sialic acid residues on the terminus of carbohydrate chains increase at P16 and mask the beta-galactose residues around rod outer segments.

Animals↗
PubMed1994

[Light-dependent changes of ribosome distribution in photoreceptor inner segments of the mouse retina].

We studied the distribution pattern of free ribosomes in the photoreceptor inner segments of adult mice with reference to environmental light. Eyeballs were obtained from animals at the light or dark phase of the ordinary cyclic light, and photoreceptor inner segments were examined by electron microscopy. In the light phase, free ribosomes were distributed in a random fashion, although meticulous observations revealed that they appeared to be arranged either in a spiral or linear form, or in isolation. In the dark phase, several free ribosomes were arranged in a clustered fashion. When animals were kept in continuous darkness as long as 27 hours, most of the inner segment free ribosomes showed a clustered pattern similar to that in the dark phase of the cyclic light. We discussed the light-dependent configurational changes of ribosomes with respect to their activity or inactivity in protein synthesis.

Animals↗
PubMed1993

Developmental change of distribution of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat retina.

A substantial change in the glycoconjugates of the rat interphotoreceptor matrix (IPM) has recently been shown to occur between post-natal day (P) 14 and P16 in rat retinas using lectin histochemistry. This suggests that the sialic acid content on the terminus of N-glycoside linked carbohydrate chains of the IPM increases between P14 and P16. In the present study, to test this hypothesis, we examined the developmental change of distribution of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat retina using in situ hybridization histochemistry. C-DNA of rat alpha 2,6-sialyltransferase was isolated by PCR and cloned into the polylinker site of Bluescript KS (+). Antisense and sense RNA probes were labelled with digoxigenin-UTP by in vitro transcription with T3 and T7 RNA polymerases, respectively. Paraffin sections of rat retinas between P12 and P42 were incubated with the antisense or sense RNA probes. Specific labelling with the antisense probe was observed strongly in the cytoplasm of all ganglion cells and weakly in partial cells of the inner nuclear layers throughout the examined postnatal days. A remarkable change was observed in the photoreceptor cells between P14 and P16. Hybridization signals of the outer nuclear layer was observed from P14, while those of the inner segments were detected on P16 and thereafter. The alpha 2,6-sialyltransferase newly expressed in the inner segments on P16 appears to sialylate the Gal beta 1, 4GlcNAc residue of N-glycosidically linked glycoconjugates of the IPM, resulting in the change of lectin staining profiles.

Animals↗
PubMed1993

Transgenic mouse lines with ectopic expression of alpha-1,3-galactosyltransferase: production and characteristics.

The cDNA of murine alpha-1,3-galactosyltransferase was placed under the control of the beta-actin promoter and cytomegalovirus enhancer, then introduced into male pronuclei of fertilized mouse eggs. The three transgenic mouse lines obtained were analysed for the expression of the transferase by staining with Griffonia simplicifolia agglutinin I-B4 (GSI-B4), which is alpha-galactosyl specific. Compared with wild-type mice, all lines of transgenic mice expressed GSI-B4 binding sites more intensely in the renal tubular brush border and lung alveolar epithelium, and newly expressed them in the photoreceptor outer segments, goblet cells of the small intestine and around spermatogonia. GSI-B4 binding sites were also detected in the liver of some transgenic mice. Even though the introduced enzyme gene was expressed in embryos, it did not severely hinder embryogenesis. The transgenic mice tended to secrete more proteins in the urine than the wild type. Furthermore, low body weights, partial damage to hair growth and early death occurred more frequently in the transgenic mice.

Animals↗
PubMed1993

A fixative suitable for in situ hybridization histochemistry.

We compared the morphology and stability of hybridization signals between paraffin sections of rat retina fixed with commonly used 4% paraformaldehyde/PBS and those fixed with a fixative containing glutaraldehyde in in situ hybridization histochemistry, using a digoxigenin-labeled RNA probe complementary for beta-galactoside alpha 2,6-sialyltransferase mRNA. Retinal detachment was frequently observed in the sections fixed with 4% paraformaldehyde-PBS, whereas the morphology was satisfactorily preserved in those fixed with either 0.5% glutaraldehyde, 4% paraformaldehyde-PBS, or 2.5% glutaraldehyde-PBS. Without glutaraldehyde, it was difficult to determine the most appropriate length of proteinase K digestion of tissue sections for facilitating probe penetration, since the optimal time for definite hybridization was variable among the retinal cells in heterogeneous layers. By addition of glutaraldehyde to paraformaldehyde or with glutaraldehyde alone, it was easy to establish the appropriate time for the unmasking procedure, since intense mRNA signals were constant throughout the retina by proteinase K digestion for more than 30-40 min. Using a fixative that causes stronger cross-linking (e.g., glutaraldehyde) is recommended to improve not only the morphology but also the stability of hybridization signals in in situ hybridization histochemistry with paraffin embedding and digoxigenin-labeled RNA probes.

Animals↗
PubMed1993

[Molecular cell glycobiology of the retina].

The distribution of beta-galactoside alpha 2,6-sialyltransferase (alpha 2,6-ST) mRNA in the retina was examined using in situ hybridization histochemistry to study the relation of sialic acid to retinal glycoconjugates. In rod-dominant rat retinas, the alpha 2,6-ST, which was found to be newly expressed in the photoreceptor inner segments on post-natal day (P) 16, appears to sialylate the rod-associated interphotoreceptor matrix (IPM). In cone-dominant squirrel retinas, alpha 2,6-ST mRNA was sparse, which suggests that cone-associated IPM does not contain sialic acids. The light-response of the IPM first occurred between P14 and P16. The IPM around cone photoreceptors did not show the response. These observations suggest that the presence of sialic acids on the termini of sugar chains around rods plays an important role in generating the light response of the IPM. The electrical resistance of the IPM is increased by removing sialic acids from the glycoconjugates of the IPM. The electrical resistance of the rod-associated sialo-IPM may be lower than that of the cone-associated asialo-IPM. The light response of the rod-associated IPM may not only facilitate the transfer of substances between rod photoreceptors and the retinal pigment epithelium, but may also be involved in the generation of the physiological features of rods. A different distribution of alpha 2,6-ST mRNA was detected in light-adapted and dark-adapted rat retinas. The mRNA was diffusely distributed through-out the inner segments in light-adapted retinas, but it was scarce in basal inner segments in dark-adapted ones. The second phase of the IPM-light response, histologically detected as accumulation of the IPM around inner segments, may be induced by an increase in the synthesis of N-glycoside linked glycoconjugates containing sialic acids. Comparing this and the electron microscopic examination of free ribosomes in the inner segments, the dispersed and clustered ribosomes correspond to active and inactive types, respectively. A progressive decrease in the mRNA-expression of alpha 2,6-ST was commonly observed in the process of various types of retinal degeneration.

Animals↗
PubMed1993

Demonstration of peripherin/rds mRNA in normal and light-damaged rat retinas by in situ hybridization histochemistry.

Cellular expression of the mRNA for peripherin/rds was studied in rat retinas by in situ hybridization histochemistry with antisense and sense probes prepared from polymerase chain reaction-amplified cDNA of the bovine peripherin/rds. Predominant mRNA signals were detected in the inner segments and distal region of the outer nuclear layer, but not in other layers of the retina including retinal pigment epithelium or in the choroid, giving evidence that the gene product, peripherin/rds, is synthesized specifically in the inner segment ribosomes to form outer segment disc membranes of photoreceptor cells. The in situ hybridization technique was applied to explore how mRNA for peripherin/rds is affected by light-induced retinal damage in rats. Following 3 days of continuous exposure to low-intensity fluorescent light, the mRNA expression in adult rats was found to be defective, although photoreceptor cells were still observed by light microscopy. After longer exposure to continuous light, the mRNA expression was severely damaged or undetectable, together with loss of photoreceptor cells.

Animals↗
PubMed1993

[Lectin histochemistry of choroidal malignant melanoma].

Tumor specimens of malignant choroidal melanoma from a 50 year-old man were studied with reference to labeling with fluorescence-labeled lectins: wheat germ agglutinin (WGA), specific for sialic acid and N-acetylglucosamine, and Ricinus communis agglutinin-1 (RCA-1), specific for galactose. Epithelioid cells occupying the apex and internal portion of a dome-shaped tumor had intense labeling of WGA but little binding to RCA-1. Spindle-shaped cells in the base of the tumor were labeled moderately with WGA and faintly with RCA-1. Neuraminidase treatment of the specimens led to a marked increase in the RCA-1 binding to both epithelioid and spindle-shaped tumor cells. The results suggest association of the malignancy of choroidal melanoma cells with oligosaccharides of cell membrane-bound glycoconjugates.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1992

Interphotoreceptor matrix in the colored-light-adapted rat.

The interphotoreceptor matrix (IPM) was examined histochemically using colloidal iron, wheat germ agglutinin and Ricinus communis agglutinin-1 for rats adapted to blue, green or red light before tissue preparation. In blue- and green-light-adapted animals, IPM was intensely stained in the apical zone of photoreceptor outer segments and in the outer and inner segment junction, conforming to the light pattern of IPM distribution in previous studies. In red-light-adapted animals, the IPM was prominent and uniform in the interstitial zone of photoreceptor outer segments, consistent with the dark pattern. The results indicate that rod photoreceptors are predominantly responsible for light-evoked changes in IPM.

Animals↗