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Biomedical subjects

R Fujita

Publications and source records attributed to R Fujita.

At least 73 records · Page 4Linked to original sources
PubMed1997

Analysis of the RPGR gene in 11 pedigrees with the retinitis pigmentosa type 3 genotype: paucity of mutations in the coding region but splice defects in two families.

X-linked retinitis pigmentosa (XLRP) is a severe form of inherited progressive retinal degeneration. The RP3 (retinitis pigmentosa type 3) locus at Xp21.1 is believed to account for the disease in the majority of XLRP families. Linkage analysis and identification of patients with chromosomal deletion have refined the location of the RP3 locus and recently have led to the cloning of the RPGR (retinitis pigmentosa GTPase regulator) gene, which has been shown to be mutated in 10%-15% of XLRP patients. In order to systematically characterize the RPGR mutations, we identified 11 retinitis pigmentosa type III (RP3) families by haplotype analysis. Sequence analysis of the PCR-amplified genomic DNA from patients representing these RP3 families did not reveal any causative mutation in RPGR exons 2-19, spanning >98% of the coding region. In patients from two families, we identified transition mutations in the intron region near splice sites (IVS10+3 and IVS13-8). RNA analysis showed that both splice-site mutations resulted in the generation of aberrant RPGR transcripts. Our results support the hypothesis that mutations in the reported RPGR gene are not a common defect in the RP3 subtype of XLRP and that a majority of causative mutations may reside either in as yet unidentified RPGR exons or in another nearby gene at Xp21.1.

Adult↗
PubMed1997

Case report: primary hepatic lymphoma associated with chronic liver disease.

We report on a case of primary hepatic lymphoma that developed in a patient with chronic hepatitis C. Given that Japan is an area endemic for both hepatitis B and C viruses, we reviewed 51 Japanese cases of primary hepatic lymphoma, addressing the question as to whether the Japanese cases have unique characteristics and whether there is a causal relationship to the presence of chronic liver disease. Primary hepatic lymphoma most commonly affected middle-aged males. Presenting symptoms and physical findings were non-specific. Aminotransferases tended to stay in the low range compared with marked increases in lactate dehydrogenase. Sixteen patients (31%) had chronic liver disease, eight had liver cirrhosis and eight had chronic hepatitis, suggesting that there is a possible aetiological link between chronic liver disease and primary hepatic lymphoma.

Adult↗
PubMed1997

Functional uncoupling between the receptor and G-protein as the result of PKC activation, observed in Aplysia neurons.

Application of either acetylcholine (ACh), dopamine (DA), histamine (HA), or Phe-Met-Arg-Phe-NH2 (FMRFamide) induces a K+-current response in the identified neurons of Aplysia under voltage clamp. This type of response is mediated by a pertussis toxin (PTX)-sensitive G-protein, Gi or Go. Extracellular application of 60 microM phorbol dibutyrate (PDBu), an activator of protein kinase C (PKC), to these cells markedly depressed all the K+-current responses to ACh, DA, HA, and FMRFamide. The depressing effect of PDBu lasted for at least 60 min despite continuous washing with the normal perfusing medium. Application of PKC inhibitors such as 100 microM H-7 or 10 microM staurosporine and PKCI(19-31) prior to the application of PDBu significantly decreased the depressing effects of PDBu. In contrast, an intracellular injection of okadaic acid (OA), an inhibitor of protein phosphatase 1 and 2A, significantly augmented the blocking effect of PDBu. Intracellular injection of the PKC catalytic subunit induced a similar depressing effect as observed with PDBu. The dose-response curves obtained with different transmitters all shifted downward after the activation of PKC, but the ED50 of each transmitter remained unchanged. Furthermore, the K+-current responses induced by the intracellular application of GTPgammaS were not depressed at all, even after the receptor-induced K+-current responses of the same cell were markedly depressed. These results strongly suggest that PKC phosphorylated a certain coupling site between the receptor and G-protein, and impaired the signal transduction necessary for triggering the K+-channel opening.

Acetylcholine↗
PubMed1997

Disease expression in X-linked retinitis pigmentosa caused by a putative null mutation in the RPGR gene.

PURPOSE: To determine the disease expression in X-linked retinitis pigmentosa (XLRP) caused by a putative null mutation in the RPGR (retinitis pigmentosa GTPase regulator) gene. METHODS: In a family with XLRP, haplotype analysis was performed with polymorphic microsatellite markers from the Xp chromosomal region, and genomic polymerase chain reaction sequencing was used to identify sequence variations in the RPGR gene. Hemizygotes and heterozygotes were evaluated clinically and with visual function tests. Optical coherence tomography (OCT) was performed on heterozygotes. Postmortem donor retinas from a heterozygote were examined by microscopy and immunocytochemistry. RESULTS: X-linked inheritance was confirmed by haplotype analysis using Xp markers. Sequence analysis of the RPGR gene identified a single base pair change, a G-->T transversion, that converts codon 52 GGA (Gly) to TGA (stop codon); the mutation segregates with the disease. A hemizygote in the third decade of life had barely measurable rod function and severely impaired cone function that diminished further over a 7-year interval. Heterozygotes varied in degree of disease expression from mild to severe. Perimetry showed loci with normal rod and cone sensitivity interspersed with loci having either equal rod and cone dysfunction or rod > cone dysfunction. Electroretinographic photoreceptor responses had equal reductions in rod and cone maximal amplitude. OCT cross sectional reflectance images of retinal regions with severe dysfunction showed reduced thickness of the retina and retinal pigment epithelium-choriocapillaris (RPE-CC) complex and increased reflections posteriorly. Regions with mild dysfunction showed similar OCT findings but with preserved retinal thickness. Retinal histopathology in a heterozygote revealed loss of photoreceptors throughout, with retention of only a few islands of cones with tiny or absent outer segments and rods lacking outer segments. CONCLUSIONS: This RPGR gene mutation, in its mildest expression in heterozygotes, causes a relatively equal disturbance of rod and cone photoreceptor function. Detectable structural change by OCT at the level of the RPE-CC can be present in patches of retina with minimal functional disturbance. More advanced disease stages in heterozygotes show greater rod than cone dysfunction, and the end stage in hemizygotes and heterozygotes is that of typical RP, with only barely detectable cone function from residual cones in a thinned retina with abnormal RPE and choriocapillaris.

Adult↗
PubMed1996

Chronic hepatitis A with persistent viral replication.

Hepatitis A virus (HAV) usually causes an acute self-limited illness. This report describes a patient with hepatitis A whose serum aminotransferase activities remained above normal and whose serum was persistently positive for immunoglobulin (Ig) M class anti-hepatitis A 31 months after the onset of hepatitis. Liver biopsy carried out 11 months after the onset of hepatitis showed histological changes consistent with chronic hepatitis of moderate severity. HAV RNA was detected by polymerase chain reaction (PCR) in feces collected at the time of the liver biopsy. Furthermore, the patient developed esophageal varices 25 months after the onset of hepatitis. We believe this to be the first reported case in which persistent replication of HAV is implicated in chronic hepatitis with the potential to develop into liver cirrhosis.

Hepatitis A↗
PubMed1996

A recombination outside the BB deletion refines the location of the X linked retinitis pigmentosa locus RP3.

Genetic loci for X-linked retinitis pigmentosa (XLRP) have been mapped between Xp11.22 and Xp22.13 (RP2, RP3, RP6, and RP15). The RP3 gene, which is responsible for the predominant form of XLRP in most Caucasian populations, has been localized to Xp21.1 by linkage analysis and the map positions of chromosomal deletions associated with the disease. Previous linkage studies have suggested that RP3 is flanked by the markers DXS1110 (distal) and OTC (proximal). Patient BB was thought to have RP because of a lesion at the RP3 locus, in addition to chronic granulomatous disease, Duchenne muscular dystrophy (DMD), mild mental retardation, and the McLeod phenotype. This patient carried a deletion extending approximately 3 Mb from DMD in Xp21.3 to Xp21.1, with the proximal breakpoint located approximately 40 kb centromeric to DXS1110. The RP3 gene, therefore, is believed to reside between DXS1110 and the proximal breakpoint of the BB deletion. In order to refine the location of RP3 and to ascertain patients with RP3, we have been analyzing several XLRP families for linkage to Xp markers. Linkage analysis in an American family of 27 individuals demonstrates segregation of XLRP with markers in Xp21.1, consistent with the RP3 subtype. One affected mate shows a recombination event proximal to DXS1110. Additional markers within the DXS1110-OTC interval show that the crossover is between two novel polymorphic markers, DXS8349 and M6, both of which are present in BB DNA and lie centromeric to the proximal breakpoint. This recombination places the XLRP mutation in this family outside the BB deletion and redefines the location of RP3.

Adult↗
PubMed1995

Molecular characterization of two forms of nontoxic-nonhemagglutinin components of Clostridium botulinum type A progenitor toxins.

The entire sequences of the type A nontoxic-nonhemagglutinin gene and an adjacent open reading frame designated as orf 22-a, which are located between the neurotoxin and the HA-35 genes were determined. SDS-PAGE and N-terminal amino acid sequence analyses of the purified type A progenitor toxins (12S, 16S and 19S) indicate that the nontoxic-nonhemagglutinins of 16S and 19S are single peptides of approximately 120k, but that of 12S has a cleavage at the site between Pro-144 and Phe-145 of this protein.

Amino Acid Sequence↗
PubMed1995

Type A and B neurotoxin genes in a Clostridium botulinum type AB strain.

The genetic structure of neurotoxin genes in a Clostridium botulinum strain producing both type A and B neurotoxins (type AB) was investigated. Analyses by polymerase chain reaction (PCR) using type-specific primers corresponding to the coding regions for N-terminals of light-chains and C-terminals of heavy-chains of type A and type B neurotoxins, and Southern hybridization of total DNA showed that the type AB strain I.P.7212 carries at least one copy each of type A and B neurotoxin genes. Partial nucleotide sequences obtained by direct sequencing of the PCR products indicate that the type A and B genes carried by this strain are not classical type A and non-proteolytic type B genes, but are similar to the type A gene present in a strain which had caused infant botulism in Kyoto and the type B gene present in a proteolytic type B strain.

Base Sequence↗
PubMed1995

Dinucleotide polymorphism at the DXS1178 locus is tightly linked to PGK1 at Xq13.

A polymorphic CA repeat (locus name DXS1178) was isolated from a 1-megabase YAC (OTCC) containing the OTC gene, located at Xp21.1. However, amplification in human-rodent hybrid cells and segregation analysis in three CEPH families mapped the DXS1178 locus at Xq13. The mapping ambiguity is apparently caused by the chimeric nature of the OTCC YAC clone.

Alleles↗
PubMed1995

Interferon and cyclosporin A in the treatment of fulminant viral hepatitis.

The prognosis of fulminant hepatitis due to non-A, non-B virus infection and acute reactivation of hepatitis B virus in HB carriers is generally poor, and the treatment of choice in Western countries is recognized as liver transplantation. In countries such as Japan where liver transplantation is not readily available, however, these intractable types of fulminant hepatitis have to be treated medically. Based on the assumption that persistent replication of causal viruses and enhanced host immune responses, especially cellular immunity, to eradicate the viruses are the key mechanism in progressive liver cell destruction and the poor prognosis, we attempted a combination treatment with interferon and cyclosporin A for these types of fulminant viral hepatitis. Subjects in the present study consisted of 1 patient with acute severe hepatitis without coma and 13 patients with coma (13 with fulminant hepatic failure) due to non-A, non-B virus and acute reactivation of hepatitis B virus. The patients were given interferon-beta, 300 x 10(4) U daily, and cyclosporin A, at an initial dose of 3 mg/kg, with tapering. Fourteen patients with coma received artificial liver support that we devised. The patient with acute severe hepatitis survived, showing histologically remarkable liver regeneration. Eight of the 14 patients with hepatic coma, all of whom were indications for liver transplantation according to the criteria of the King's College group, survived. Decreased transaminase level, increased liver volume, and histological liver regeneration were observed in all the survivors. The combination of interferon and cyclosporin A is worth attempting in fulminant hepatitis caused by non-A, non-B virus and acute reactivation of hepatitis B virus in HB carriers.

Acute Disease↗
PubMed1994

Mapping the Friedreich ataxia locus (FRDA) by linkage disequilibrium analysis with highly polymorphic microsatellites.

The Friedreich's ataxia locus (FRDA) is tightly linked to markers D9S5 and D9S15 located in 9q13-q21. Cumulated maximum lod scores between FRDA and D9S5 and between FRDA and D9S15 are above 36 and 61, respectively, at a recombination fraction of 0, indicating that recombination events needed to orient the search of the gene are very difficult to identify and ascertain. We have established a 1 Megabase PFGE map around D9S5 and D9S15 and isolated a corresponding 530 kb YAC contig. We found that the two markers are 260 kb apart. This result was surprising, since D9S5 and D9S15 were independently isolated, but in agreement with the strong linkage between the two loci (lod score > 35 at a recombination fraction of 0). Seven clusters of rare cutter enzyme sites (CpG islands), which are potential indicators of genes, were identified in the 1 Megabase region by PFGE analysis and YAC mapping. The search for genes around the CpG islands is in progress. To map the Friedreich ataxia locus in the absence of clearly identified recombination events, we chose an alternative approach based on haplotype analysis of patients from small populations with precise geographic and historical origins, such as the Louisiana-Acadians, deported from Nova-Scotia about 150 years ago and who remained isolated for historical and cultural reasons. In this population, a single mutation, associated with a specific haplotype may account for the majority of Friedreich ataxia cases. Haplotypes different from the major haplotype at one or the other extremity can indicate ancient recombinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosome Mapping↗