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N Ohba

Publications and source records attributed to N Ohba.

At least 19 recordsLinked to original sources
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↗
PubMed1991

[Classification of light-evoked distribution of interphotoreceptor matrix].

Distributional patterns of the interphotoreceptor matrix (IPM) under several different light conditions were examined in adult rats using colloidal iron staining. In the dark, the IPM distributed uniformly throughout photoreceptor outer segments including apical halves of inner segments. After exposure to light for 1 min, the colloidal iron-bound IPM concentrated in bands at apical and basal regions of outer segments and at apical inner segments. After exposure to light for 5-30 min, the IPM distributed throughout inner segments, in addition to the distribution at apical and basal outer segments. In excessive light, diffuse IPM staining was observed throughout the photoreceptor layer. These findings suggest that the light response of the IPM around outer segments precedes that around basal inner segments. It is also remarkable that the excessive light-induced distributional pattern of the IPM is similar to patterns in inherited retinal dystrophy and light-induced retinal degenerations.

Animals↗
PubMed1991

[Lectin binding in the interphotoreceptor matrix in neuraminidase-induced retinal detachment].

Binding sites of fluorescence isocyanate-labeled lectins, peanut agglutinin (PNA) and Ricinus communis agglutinin-1 (RCA-1), were studied in the interphotoreceptor matrix (IPM) of adult rat retinas that were pretreated with an intravitreous injection of neuroaminidase. The localization of binding sites to the subretinal IPM differed significantly between the two lectins. PNA bound to the subretinal IPM components in a cord-like fashion that formed a bridge between the apical photoreceptor outer segments and the surface of the RPE. On the other hand, RCA-1 showed homogeneously prominent binding to the subretinal space IPM, the intensity of which appeared to inversely correlate with the extent of neuraminidase-induced retinal separation. The results suggest that the IPM may consist of mucin-type glycoconjugates as recognized by PNA and serum-type ones as bound by RCA-1, and that these IPM components may play different roles in the maintenance and organization of photoreceptor-RPE complex, e.g. the mucin-type for the retinal adhesion and the serum-type for the transport of metabolites.

Animals↗
PubMed1990

The effects of pyrimidine and purine nucleotides on sialyltransferase activity in bovine neurosensory retina.

Effects of nucleotide phosphates on the sialyltransferase activity in the neurosensory retina of the bovine eye were studied. Enzyme activity was assayed using cytidine monophosphate-[14C]-N acetylneuraminic acid as a substrate and desialylated fetuin as an exogenous acceptor. Cytidine-5'-diphosphate and adenosine triphosphate inhibited the enzyme activity. Uridine diphosphate and guanosine diphosphate increased the enzyme activity at low concentrations and decreased the activity at high concentrations. Cyclic adenosine monophosphate and cyclic guanosine monophosphate increased the enzyme activity at concentrations up to 8 mM. It is thus concluded that sialyltransferase activity of the neural retina may be affected by various nucleotides, its alteration depending on either the type of nucleotides or their concentration.

Animals↗
PubMed1989

Noninfectious anterior uveitis in patients infected with human T-lymphotropic virus type I.

A consecutive series of 34 patients with HTLV-I-associated myelopathy (HAM), a neurological disease associated with human T-lymphotropic virus type I (HTLV-I), were studied with reference to endogenous ocular disorders. These patients were examined at the Kagoshima University Hospital between 1986 and 1988. Five of the 34 HAM patients showed noninfectious, granulomatous anterior uveitis responding to corticosteroid therapy and/or retinal microvascular changes such as isolated cotton-wool spots; one of the patients had recurrent uveitis. Additionally, twelve of 30 patients who had been infected with HTLV-I but remained healthy systemically had ocular manifestations similar to those in HAM patients were included in this study. The ocular lesions in these patients were not explained by any established disorders that manifest uveitis or retinal microangiopathy. Some of the HTLV-I-seropositive patients with ocular disorders showed antibodies against HTLV-I in the aqueous humor. This might have resulted from diffusion of serum antibodies through a damaged blood-aqueous barrier or local synthesis of antibodies. The HTLV-I infection might be primarily responsible for a certain form of endogenous anterior uveitis that has remained hitherto etiologically undefined.

Adult↗
PubMed1989

Pigmentary retinal degeneration in patients with HTLV-I-associated myelopathy.

Ophthalmological evaluations were made of the records of a series of 38 patients with HTLV-I-associated myelopathy, a chronic progressive myelopathy caused by human T-lymphotropic virus type I (HTLV-I). Four patients with no contributory family history showed pigmentary degenerative changes of the retina and choroid. Two of the patients (73-year-old woman, 68-year-old woman) had a progressive visual loss and night blindness with morphologic and functional features of diffuse pigmentary retinal degeneration. The other two patients (59-year-old man, 72-year-old man) complained of recently developed visual loss with sectorial or regional retinochoroidal atrophy. These elderly patients claimed that they had been healthy until a few years before presentation, not only visually but also neurologically. It was concluded, together with an epidemiologic consideration, that the coexistence of pigmentary retinal degeneration and HTLV-I-associated myelopathy is not simply chance but indicates a close association between the two conditions. It is proposed that HTLV-I infection might be a primary causative factor of degenerative changes of the retina and choroid, although the pathogenesis remains to be defined.

Aged↗