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Biomedical subjects

N Ohba

Publications and source records attributed to N Ohba.

At least 91 records · Page 5Linked to original sources
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

Clinical features of HTLV-I associated uveitis.

The prevalence of human T cell lymphoma virus type 1 (HTLV-I) was studied among patients with endogenous uveitis. Twelve (15.8%) of 76 uveitis patients with known aetiology or clinical entity were seropositive, the prevalence being comparable with that in the general population of the southwestern area of Japan where HTLV-I is highly endemic. In the comparison, 32 (41.0%) of 78 patients with aetiology or entity undefined uveitis were seropositive for HTLV-I, which indicated a significantly higher seroprevalence than controls matched for sex and age. The 32 cases of clinical entity undefined, HTLV-I positive uveitis were characterised by acute granulomatous or non-granulomatous uveal reactions which were accompanied by vitreous opacities and retinal vasculitis. The uveal inflammatory and retinal vascular changes responded well to topical and/or systemic corticosteroids and resolved in a few weeks in the majority of cases with favourable visual outcome. The disease affected one or both eyes, and eight cases (25%) showed recurrence within a year. The general condition of the patients remained well otherwise during a follow up study (mean follow up time 15.4 months), except for three cases with a possible association of hyperthyroidism. These findings provide additional information favouring an association between HTLV-I and isolated uveitis, a new disease entity which should be termed HTLV-I-associated uveitis.

Adolescent↗
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

A multicenter study of typical retinitis pigmentosa in Japan.

A nationwide, multicenter study of typical retinitis pigmentosa was carried out in collaboration with 13 university hospitals throughout Japan. A total of 253 patients, 122 males and 131 females, with a wide range of ages (mean 48 years), were registered during a two-month period in 1989. Determination of inheritance pattern revealed 30.2% autosomal recessive cases, 15.4% autosomal dominant, 0.5% X-linked, and 48.9% simplex, indicating a relative decrease in autosomal recessive cases and a relative increase in simplex cases in recent decades. The age at onset, initial symptom, and visual functions including visual acuity, visual field and electroretinogram showed a marked interindividual variability, but statistical analysis demonstrated that visual defects progressed with increasing age and disease duration. A correlation between the phenotypic variation and the genetic type was observed. This survey of retinitis pigmentosa in Japan provides information for counseling and rehabilitation of patients and encourages basic and clinical research of this genetic disease.

Adolescent↗
PubMed1993

[HTLV-I and ocular disease].

Human T-lymphotropic virus type 1 (HTLV-I) has an etiologic role in adult T-cell leukemia (ATL) and HTLV-I associated myelopathy (HAM). This paper reviews the ophthalmic literature relevant to the retrovirus. Patients with ATL may have intraocular invasion of proliferated T lymphocytes, lymphomatous lesion in the ocular adnexa, or cytomegalovirus retinitis due to immunocompromisation. Patients with the chronic neurological disease HAM may present with retinal vasculitis, isolated cotton-wool spots, probably immune-mediated uveitis, and/or retinochoroidal degenerative change. Similar retinal vascular or uveal inflammatory disease is occasionally seen in otherwise healthy HTLV-I carriers. Clinical and epidemiologic data suggest the existence of HTLV-I associated uveitis (HAU) that is assumed to be associated with the retrovirus. Further ophthalmic research is encouraged to elucidate the clinical significance of the worldwide HTLV-I infection.

Carrier State↗
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

Sequence homology of NADH CoQ reductase subunit IV with nucleotide-requiring enzymes.

The amino acid sequence of NADH CoQ reductase subunit IV is highly homologous with those of enzymes such as ATPase, argininosuccinate synthetase and adenylate kinase. Replacement of arginine by histidine in three enzymes was shown to result in loss of enzyme activity, causing pathologies including citrullinemia. As an analogy, we submit the hypothesis that replacement of arginine by histidine in NADH CoQ reductase subunit IV leads to its activity change, and ultimately results in Leber's hereditary optic neuropathy.

Adenosine Triphosphatases↗
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↗
PubMed1992

Antibodies against human retinal proteins in serum from patients with cone dystrophy.

Eleven patients with cone dystrophy were examined for serum antibodies against human retinal proteins. Sera were screened by immunoblotting methods using human retinal proteins as antigens. Three cases from different families showed a distinct band at the molecular weight of 14 kDa; the hereditary pattern of these seropositive cases was autosomal recessive or sporadic with parental consanguinity. The serum antibodies were negative in the other sporadic or autosomal dominant cases of cone dystrophy with similar clinical features, in cases of various ocular diseases including macular dystrophies, and in healthy adults. No sera tested showed any specific antibodies against proteins from the human optic nerve or spinal cord.

Adolescent↗
PubMed1992

Nonfamilial and unusual cases of Leber's hereditary optic neuropathy identified by mitochondrial DNA analysis.

Peripheral blood mitochondrial DNA (mtDNA) samples from 11 patients with acute optic neuritis or insidious optic atrophy were examined for the mutation at nt 11778 and nt 3460 in polymerase chain reaction products. The mtDNA mutation at nt 11778 was evident in 8 cases, which led to a definite diagnosis of Leber's hereditary optic neuropathy (LHON); 4 of the cases were familial and the remaining 4 cases were nonfamilial. None of the 11 patients showed the nt 3460 mutation. The symptoms and signs were variable among the LHON cases with nt 11778 mutation. Assessment of mtDNA provides a useful diagnostic aid for clinically undefined, seemingly nonfamilial or atypical cases of Leber's hereditary optic neuropathy, particularly in bilateral, insidious optic nerve disease in early childhood.

Acute Disease↗
PubMed1992

[Light response of the interphotoreceptor matrix in inherited degenerative retina].

The light-evoked distributional changes of the interphotoreceptor matrix (IPM) in mice with three types of inherited retinal degeneration were examined by histochemistry using fluorescence isocyanate-labeled wheat germ agglutinin. In mice with nervous and Purkinje cell degeneration, the light response of the IPM was still somewhat preserved during the early stage of photoreceptor degeneration, whereas it became extinct when the outer segments (OS) became moderately or markedly shortened. In mice with slow retinal degeneration mice without development of OS, the light response of the IPM was absent throughout the developmental stages. These findings suggest that the presence of normal OS is necessary for the light response of the IPM to occur.

Animals↗
PubMed1991

Seroprevalence of antibodies to HTLV-I in patients with ocular disorders.

Human T-lymphotropic virus type 1 (HTLV-I) has been shown to spread worldwide and to be responsible for distinct systemic diseases, namely adult T-cell leukaemia and HTLV-I-associated myelopathy. Immune-mediated, inflammatory lesions in the lungs, joints, and lacrimal glands (Sjögren's syndrome) are also suggested to be associated with the retrovirus. We studied seroprevalence of antibodies to HTLV-I in patients with various ocular disorders who are residents of south-west Japan, one of the endemic areas of HTLV-I. Of 310 patients with ocular disease 72 (23.2%) were seropositive. This seroprevalence did not differ significantly from that of the general population of the area. As regards individual ocular diseases, aetiologically undefined nonspecific uveitis showed a significantly high seropositivity for HTLV-I. Of 44 patients 18 (40.9%) were seropositive. Their clinical features were acute or subacute, transient and sometimes recurrent, and granulomatous changes in the anterior uvea. Patients with isolated cotton-wool spot of the retina, non-familial retinitis pigmentosa, or keratoconjunctivitis sicca did not show any significantly high prevalence of HTLV-I infection.

Adolescent↗
PubMed1991

[Aging effects on the light response of the interphotoreceptor matrix as revealed by binding of Ricinus communis agglutinin-1].

This study intended to explore whether the light response of the interphotoreceptor matrix (IPM) is affected by aging. The binding pattern of fluorescence-labeled Ricinus communis agglutinin-1 (RCA) to IPM was examined histochemically in 2 month-old and 1.5 year-old rats under light- and dark-adapted conditions. Two month-old animals showed obvious light-evoked changes in the rod associated IPM: the photoreceptor inner segment zone showed a greater fluorescence than the outer segment zone in the light, whereas the staining-intensity of the former was less than that of the latter in the dark. On the other hand, 1.5 year-old rats did not show such light-evoked IPM responses as in 2 month-old animals: no light-dark differences were found in RCA-1 binding. The scarce, linear, preferential binding of RCA-1 to the cone-associated IPM was the same in both lighting conditions independent of the age.

Aging↗
PubMed1991

[Detection of dual phase of light response of interphotoreceptor matrix].

The postnatal development of light-evoked changes in the interphotoreceptor matrix (IPM), a complex of the extracellular matrix that surrounds the photoreceptors and lies between them and the retinal pigment epithelium, was studied by use of a histochemical probe colloidal iron in rats at various postnatal days of age. In the dark, IPM constituents distributed uniformly throughout the outer segment zone and in the apical region of the inner segment zone; this dark pattern of IPM distribution was commonly observed in animals ranging from postnatal day 12 to one year. In the light, little changes were observed at postnatal day 12, followed by varying light-evoked changes in the IPM with increasing ages. At postnatal day 14, the IPM constituents showed a distribution towards the basal region of the inner segment zone along with the dark pattern. At postnatal day 16, they concentrated in bands at the apical and basal region of the outer segment zone, and also in the inner segment zone with expansion from the apical to basal region with increasing time after light exposure. At age one year, the light-adapted IPM constituents were distributed in a manner similar to that on postnatal day 14. The present results confirm the light-evoked changes in the IPM as revealed by colloidal iron-recognized IPM components and provide evidence for postnatal development of the light-evoked changes in the IPM components, whereby the changes appeared earlier and were preserved longer in the basal region of the inner segment.

Adaptation, Ocular↗
PubMed1991

[Effects of fixation and light conditions on distribution of interphotoreceptor matrix].

By using albino, adult rats, the effects of different light conditions during enucleation and fixation on the staining of the interphotoreceptor matrix (IPM) with colloidal iron were examined. When the eyes were enucleated in the dark or under a fluorescent lamp, followed by immersion-fixing in the dark, the IPM around the photoreceptor outer segments (OS) and apical inner segments (IS) was uniformly stained. When the eyes were enucleated in the light, and were immersion-fixed in the light, the staining pattern of the IPM was dependent on the light conditions during the fixation. By increasing the intensity and the exposure-time of the light, the intensity of the interstitial IPM-staining around the OS decreased except for the apical- and basal-regions, whereas that of the IPM staining around the IS increased from the basal- to the apical-region. When the rat was perfused with the fixative in the light, the diffuse IPM staining around the IS was especially remarkable. In cases in which it is only possible to apply immersion-fixation, it is necessary to remove the light effects during the fixation in order to obtain consistent results with IPM-histochemistry. For this purpose, it may be effective to cover the bottle for fixation with aluminum foil immediately after the enucleation.

Animals↗