Search PubMed⌕ Search

Biomedical subjects

N Ohba

Publications and source records attributed to N Ohba.

At least 19 recordsLinked to original sources
PubMed1999

REP-1 gene mutations in Japanese patients with choroideremia.

BACKGROUND: Choroideremia (CHM) is an X-linked progressive dystrophy of the choroid, retinal pigment epithelium, and retina. Recently, the REP-1 gene was isolated and the causative mutations in the gene were detected in patients with CHM. In a previous study, we described a Japanese family with CHM who had a mutation in the REP-1 gene. In the present study, we performed extensive analysis of the REP-1 gene in patients with CHM from several institutions in Japan. METHODS: Twenty-six patients with CHM and 5 unaffected females from 22 independently ascertained families were examined. Exons 1-15 of the REP-1 gene were screened by single-strand conformation polymorphism. The DNA fragments suspected of any variations were directly sequenced. RESULTS: Fifteen different mutations, including one previously reported mutation, were detected in 18 families. In addition, carrier status was proven in four unaffected females found to be heterozygous for the mutant allele. CONCLUSIONS: Fifteen different mutations of the REP-1 gene were detected in 18 Japanese families. There were no hot spots for the mutations and no missense mutations. The results show that REP-1 gene defects cause CHM in Japanese patients, and the mutations in these Japanese patients differed from the mutations reported for CHM patients in Europe, Canada, and America except for R267X and 1313delTC. These findings suggest that the mutations occurred independently in the Japanese patients.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Hepatocyte growth factor stimulates cell growth and enhances the expression of transforming growth factor alpha mRNA in AsPC-1 human pancreatic cancer cells.

We investigated the effects of hepatocyte growth factor (HGF) and transforming growth factor alpha (TGF alpha) on cell growth in four human pancreatic cancer cell lines. Changes in the expression of mRNAs of HGF, c-met, TGF alpha, and epidermal growth factor receptor (EGFR) by treatment with HGF and TGF alpha were observed. Cell growth with growth factors was assessed with the MTT assay and compared with basal growth without growth factors. Although HGF stimulated cell growth in AsPC-1, COLO-357, and T3M4 cells, Panc-1 cells showed no response to HGF. TGF alpha stimulated the growth of all the above cells. The expression of c-met mRNA under nonstimulated conditions was detected with Northern blotting in all cells. Treatment with HGF slightly enhanced the expression of c-met mRNA only in COLO-357 cells. The intensity of EGFR expression was consistent, and HGF mRNA was not detected during induction experiments in any cell type. Concomitant treatment with HGF and TGF alpha exerted an effect that was additive or less on the growth of all cells. Expression of TGF alpha was enhanced by HGF treatment only in AsPC-1 cells. These results suggested that HGF and TGF alpha stimulated cell growth through a final common pathway of signal transduction.

Blotting, Northern↗
PubMed1999

A novel truncating mutation of cytochrome P4501B1 (CYP1B1) gene in primary infantile glaucoma.

PURPOSE: To report a novel mutation of the CYP1B1 gene in a Japanese patient with primary infantile glaucoma. METHODS: DNA was extracted from leukocytes of six unrelated patients with primary infantile glaucoma. The coding regions of the CYP1B1 gene were amplified by polymerase chain reaction, examined by agarose gel separation and heteroduplex methods, and directly sequenced. RESULTS: One of the patients with primary infantile glaucoma had a mutation of the CYP1B1 gene, with an abnormal shift in agarose gel separation and heteroduplex analysis. Direct sequencing disclosed a homozygous insertion of guanine at nucleotide 1620 of exon 3, which produced a frameshift leading to premature termination of amino acid translation. The patient was male and had sporadic, classic primary infantile glaucoma. None of the other five patients with infantile glaucoma, the 30 patients with primary adult-onset glaucoma, or the 70 healthy control subjects showed any abnormalities in the CYP1B1 gene. CONCLUSIONS: This is the first report of CYP1B1 gene mutation in primary infantile glaucoma from the Eastern world. CYP1B1 gene mutation for primary infantile glaucoma spreads worldwide, but its prevalence may have ethnic or geographic differences.

Aryl Hydrocarbon Hydroxylases↗
PubMed1999

[Sorsby's fundus dystrophy: a literature review].

BACKGROUND: Sorsby's fundus dystrophy (SFD) is an autosomal dominant macular dystrophy first described in a 1949 study of five British families, and it has received attention because of its clinical similarity to age-related macular degeneration and recent identification of the pathogenic gene. CLINICAL FEATURES: To date, about twenty families with SFD have been reported from Europe, North America, South Africa, Australia, and Japan. A review of the literature found that the age of onset is usually during the fourth or fifth decade of life, the prominent ophthalmoscopic finding is hemorrhagic or atrophic lesion in the macula, and functional prognosis is usually unfavorable due to additional peripheral chorioretinal dystrophy, ultimately leading to poor ambulatory vision in the late decades of life. MOLECULAR GENETICS: Recent molecular studies have identified mutations in the tissue inhibitor of metalloproteinases-3 (TIMP 3) gene as the pathogenic gene defect. CONCLUSIONS: TIMP 3 gene examinations not only allow accurate diagnosis but also lay the groundwork for future studies of potential therapeutic protocols.

Corneal Dystrophies, Hereditary↗
PubMed1998

A novel splice site mutation in the tissue inhibitor of the metalloproteinases-3 gene in Sorsby's fundus dystrophy with unusual clinical features.

Sorsby's fundus dystrophy (SFD) is an autosomal dominant macular dystrophy which is developed usually in the third or fourth decade of life, and is characterized by central visual loss and nyctalopia due to fundus changes of exudative or atrophic macular lesions. Its functional prognosis is usually poor because of disciform macular scars and peripheral chorioretinal atrophies. To date, five different mutations in the tissue inhibitor of the metalloproteinases-3 (TIMP3) gene have been identified in families of a wide geographic origin, all of which are missense mutations that cause replacement by cysteine of conserved amino acids in the C-terminus of exon 5 of TIMP3. We have studied two Japanese families with SFD, the first report from the Eastern world, and identified a novel 3' splice site mutation in the TIMP3 gene, namely a single base insertion at the intron 4/exon 5 junction which converts the consensus sequence CAG to CAAG in the splice acceptor site. In addition, our patients displayed a distinctive clinical expression in that they developed macular dystrophies at an approximately 30-year later age of onset and preserved functional vision until later life with essentially uninvolved peripheral retina. The present findings may provide some insight into the genotype-phenotype relationship in SFD.

Aged↗
PubMed1998

Ultracytochemical demonstration of glycogen in cone, but not in rod, photoreceptor cells in the rat retina.

The presence of native glycogen in photoreceptor cells of the rat retina has not been identified in the literature. We have studied this ultracytochemically. After perfusion with glutaraldehyde fixative, the eyes were enucleated, and the retinal tissues, postfixed with OsO4, were embedded in epoxy resin. Some tissues were treated with saliva before postfixation. Ultrathin sections, stained by the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method or with uranyl acetate and lead citrate, were examined by electron microscopy. On routinely stained sections, glycogen particles seemed to be absent in the cytoplasmic matrix of the photoreceptor cells because they were indistinguishable from the numerous ribosomes. This was due to a similarity in size and electron density. After PA-TCH-SP staining, fine electron-dense reaction products appeared on small cytoplasmic particles (but not on ribosomes) in the inner segments, perikarya and synaptic terminals of a subpopulation of photoreceptor cells. These particles, 15-25 nm in diameter, were identified as beta-particles of glycogen because of their susceptibility to enzyme digestion. The glycogen-rich photoreceptor cells were thought to be cone cells by reasons of their morphological features, such as synaptic terminals, nuclei and outer segments. These results suggest that the cone, but not the rod, photoreceptor cells in the rat contain abundant glycogen.

Animals↗
PubMed1998

Retinal manifestations in mitochondrial diseases associated with mitochondrial DNA mutation.

PURPOSE: To scrutinize retinal involvement associated with distinct mitochondrial DNA (mtDNA) defects, we reviewed the records of a consecutive series of patients with various mitochondrial diseases. METHODS: Clinical, laboratory and mtDNA studies were performed in: five patients with Kearns-Sayre syndrome (KSS); six patients with chronic progressive external ophthalmoplegia (CPEO); three patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode (MELAS); three patients with myoclonic epilepsy and ragged-red fibers (MERRF); 20 patients with Leber's hereditary optic neuropathy (LHON); 30 patients with simple diabetes mellitus. RESULTS: All KSS patients with neurologic and cardiac symptoms associated with a deletion of mtDNA in muscle biopsy specimens showed widespread retinal pigmentary changes characterized by salt- and pepper-like appearance of the fundus. Three of six patients with CPEO, a mild variant of KSS, showed subtle defects at the level of retinal pigment epithelium of the posterior pole, although mtDNA deletion was similar to that in KSS. Of three patients with MELAS syndrome, one patient showed juvenile cataract and mild retinal pigmentary defect in the posterior pole. Of three patients with MERRF syndrome associated with a mtDNA mutation at nucleotide position (np) 8344, one patient showed mild pigment disorder in the posterior pole in addition to optic neuropathy. Two of 20 patients with LHON associated with a mtDNA mutation at np 11778 showed mild pigmentary defect in the macula together with typical optic neuropathy. In addition, two of 30 patients with isolated diabetes mellitus showed a mtDNA mutation at np 3243 (MELAS mutation), but they did not present with any other neurologic or multisystem disorder. CONCLUSION: The retina, in particular the retinal pigment epithelium, is highly vulnerable to be involved by mtDNA defect, and the retinopathy is phenotypically variable and frequently subclinical, depending to some extent on the type or site of mtDNA defect.

Adolescent↗
PubMed1997

Genotypes of aldehyde dehydrogenase and alcohol dehydrogenase polymorphisms in patients with Leber's hereditary optic neuropathy.

To define whether alcohol drinking provides a risk for Leber's hereditary optic neuropathy (LHON), the genotypes of low K(m) aldehyde dehydrogenase (ALDH2) and alcohol dehydrogenase type 2 (ADH2), major enzymes involving the alcohol metabolism, were examined in 29 unrelated Japanese patients with LHON associated with mitochondrial DNA 11778 mutation, 24 unrelated asymptomatic carriers with the mutation and 57 normal controls without the mutation. PCR-restriction detection revealed three genotypes of ALDH2 and ADH2. The allele frequencies of either enzyme in LHON patients, asymptomatic carriers, or both, did not differ from those in normal controls. There is no association between LHON and genotypes of alcohol-metabolizing enzymes. However, six of the LHON patients had frequent alcohol consumption, while none of the asymptomatic carriers claimed frequent drinking habit. Thus, we could not make a denial of drinking effects on optic nerve damage in LHON.

Adolescent↗
PubMed1997

[Lectin histochemistry of the glycoconjugates in conjunctival goblet cells].

The distribution of O- and N-linked glycoconjugates in human conjunctival goblet cells was examined histochemically using biotinylated and fluorescence-labeled lectins simultaneously. Both peanut agglutinin and Erythrina cristagalli agglutinin, specific for O- and N-linked sugar chains, respectively, bound to the same goblet cell, which demonstrated that a conjunctival goblet cell produces and contains both types of glycoconjugates. Maackia amurensis lectin II, specific for sialic acid alpha 2, 3 galactose, bound to the goblet cells, while Sambueus nigra agglutinin, specific for sialic acid alpha 2, 6 galactose, did not. This observation suggested that the terminal galactosyl residue of the glycoconjugates is alpha 2, 3-sialylated in the human conjunctival goblet cells.

Conjunctiva↗
PubMed1997

[Lectin-histochemical analysis of pleomorphic adenoma of the lacrimal gland].

The sugar structures of the glycoconjugates in pleomorphic adenoma of the lacrimal gland were analyzed by examining the binding sites of 5 biotinylated lectins on tissue sections with or without sialidase digestion. Both galactose (Gal) beta 1,3 N-acetylgalactosamine and Gal beta 1,4 N-acetylglucosamine were present on the surfaces of ductal basal cells and stromal cells. The galactsyl residues in the glycoconjugates of ductal basal cells were either sialylated or exposed, whereas those of stromal cells were all sialylated. Since the synthesis of sugar chains of glycoconjugates is terminated by sialylation, their structure may mature as they progress from ductal basal cells to stromal cells.

Acetylgalactosamine↗
PubMed1997

[Glycohistochemical analysis of rat eyelid epithelium].

The glycoconjugates in eyelids of adult rats were examined by lectin histochemistry and in situ hybridization histochemistry. Since Maackia amurensis lectin II and jacalin bound to the cell membranes of basal and apical epithelial cells, sialic acid alpha 2,3 galactose (Gal) beta 1,3 N-acetylgalactosamine (GalNAc) sequence is present in the glycoconjugates of their cell membranes. Peanut agglutinin bound to the cell membranes of spinous cells in the middle of the epithelium, suggesting that Gal beta 1, 3 GalNAc sequence is present in their glycoconjugates. The mRNA of Gal beta 1,3 GalNAc alpha 2,3-sialyltransferase was detected in the cytoplasm of the epithelial cells other than the basal cells. This observation suggests that sialoglycoconjugates may be newly synthesized in the spinous and apical cells, while the glycoconjugates in the cell membranes of basal cells may be produced at an early stage of development and are stable without turnover.

Animals↗
PubMed1997

[Glycohistochemical analysis of seborrheic keratosis in eyelids].

The glycoconjugates of seborrheic keratosis in the eyelids were examined by in situ hybridization histochemistry using cRNA probes for sialyltransferase (ST) and lectin histochemistry. We considered that the cells, which expressed both cytoplasmic distribution of ST-mRNA and binding of lectins specific for sialic acids to the cell surfaces, were actively producing sialoglycans. We also considered that the cells whose surfaces were stained with the lectins without cytoplasmic distribution of ST-mRNA have completed the synthesis of sialoglycans. These viewpoints suggest that the O-linked sialoglycan, whose turnover-rate is slow, may be distributed over the cells of the thickened spinocellular layer in the tumor of seborrheic keratosis and involved in its pathomechanism. It also appears that the turnover rate of the terminal sialic acids in the N-linked glycan in the spinocellular layer may be fast.

Aged↗
PubMed1997

[Lectin-histochemical study of early postnatal eyelid epithelium of the rat].

The glycoconjugates in neonate rat eyelids at postnatal day 0 or 1 were examined by lectin histochemistry. Maackia amurensis lectin II, which recognizes sialic acid alpha 2, 3 galactose beta 1, 3 N-acetylgalactosamine (Gal beta 1, 3 GalNAc) or sialic acid alpha 2, 3 galactose beta 1, 4 N-acetylglucosamine, bound to the cell membranes of the epithelial basal cells, suggesting that the glycoconjugates containing these sugar chains are present on their cell membranes. With respect to the binding of the Gal beta 1, 3 GalNAc-specific lectin, jacalin, whose binding is not inhibited by the terminal sialic acid, bound to the cell membranes of the epithelial basal cells, whereas peanut agglutinin, whose binding is inhibited by the terminal sialyl residue, did not bind to their cell membranes. These findings suggest that all the residues of Gal beta 1, 3 GalNAc in the glycoconjugates of their cell membranes are sialylated as the mature form.

Animals↗
PubMed1997

[Glycohistochemical analysis of apoptotic bodies in eyelid tumor].

To clarify the relation between the mechanism of apoptosis in tumor tissues and sialic acids on the termini of sugar chains of glycoconjugates, a case of squamous cell carcinoma was examined using immunohistochemistry and glycohistochemistry. Immunohistochemistry and in situ hybridization histochemistry suggested that sialylation by the sialyltransferase in dominant in tumor cells, whereas hydrolysis of sialic acids by the sialidase is dominant in apoptotic bodies. Lectin histochemistry revealed that sialic acid alpha 2, 3 galactose beta 1, 3 N-acetylgalactosamine (Gal beta 1, 3 GalNAc) is present on the surfaces of tumor cells, and Gal beta 1, 3 GalNAc is present on those of apoptotic bodies. The exposed Gal beta 1, 3 GalNAc owing to the decrease in sialic acids on the surfaces of apoptotic bodies may be recognized by the C-type lectin on the macrophage for phagocytosis.

Aged↗
PubMed1997

[Immunohistochemical distribution of keratin in malignant tumors of eyelids].

The type and distribution of keratins (K) in malignant tumors of eyelids were examined immunohistochemically to understand the pathomechanism of intercellular interactions. All of the tumor cells in the basal cell carcinoma were positive for K14, which is specific for basal cells, whereas all of them were negative for K10, which is specific for suprabasal layers in stratified squamous epithelia. These findings suggest that basal cell carcinoma may consist of uniform, basal cell-like tumor cells. On the other hand, the squamous cell carcinoma and sebaceous carcinoma, which were positive for either K14 or K10 to varying extent, may consist of various tumor cells with different types and degrees of differentiation. In these tumors, K14 was frequently detected throughout the border cells of the tumor mass. Apoptotic bodies were detected at the region where this continuous distribution of K14 was interrupted. These findings may help to clarify the pathomechanism of the interactions between the tumor cells and stromal cells.

Adenocarcinoma, Sebaceous↗
PubMed1997

[Immunohistochemical localization of cytosolic sialidase in the epithelium of rat cornea and conjunctiva].

The binding sites of the anti-cytosolic sialidase antibody and Maackia amurensis lectin II (MAL II: specific for sialic acid alpha 2, 3 galactose) in the epithelium of the rat cornea and conjunctiva were immunohistochemically and lectin-histochemically examined, respectively. Cytosolic sialidase was detected in the cytoplasm of the middle and basal epithelium of the cornea and conjunctiva, whereas MAL II bound to the apical region of their epithelium and the mucous of the goblet cells. The predominant action of the cytosolic sialidase, which is stronger than that of the sialyltransferase, may inhibit the terminal sialylation of the glycoconjugates at the middle and basal regions of the epithelium of the cornea and conjunctiva.

Animals↗
PubMed1997

[Effects of the age on the apoptotic and proliferative reactions in the constant light-exposed rat retina].

The effects of age (5-3 weeks old) on apoptotic changes in the rat photoreceptor cells induced by 3 days of constant light exposure were examined using TUNEL (TdT-mediated dUTP nick end labeling). The effects on the expression of the Ki67-antigen, which is a proliferative marker, in these photoreceptor cells were also examined by immunohistochemistry. The results suggested that the number of positive cells in the outer nuclear layer of the superior hemisphere is higher than in the inferior nuclear layer in both the TUNEL reaction and the distribution of the Ki67 antigen, and that the number of positive cells increases with age in general. The cells of monocytes/macrophages may locally proliferate in the retina to phagocytose the apoptotic bodies owing to the degeneration of photoreceptor cells. The present findings revealed that the rates of these reactions may generally increase with age.

Aging↗