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Biomedical subjects

N Okada

Publications and source records attributed to N Okada.

At least 343 records · Page 19Linked to original sources
PubMed1991

Detection of the membrane inhibitor of reactive lysis (CD59) in diseased neurons of Alzheimer brain.

The membrane inhibitor of reactive lysis (MIRL) protects host cells from complement-mediated lysis. It was detected immunohistochemically in tangled neurons and dystrophic neurites of Alzheimer disease (AD) tissue in a pattern highly similar to that observed for the membrane attack complex of complement, C5b-9. MIRL was also detected in cultured IMR-32 neuroblastoma cells. The mRNA for MIRL was detected in RNA extracts of both AD and normal brain. These data provide the first evidence of brain neuronal expression of MIRL and its upregulation in neurons exposed to complement attack. They are consistent with the previously advanced hypothesis that complement-mediated neuronal injury may play a role in AD.

Alzheimer Disease↗
PubMed1991

Shaping and reshaping of salmonid genomes by amplification of tRNA-derived retroposons during evolution.

Three families of tRNA-derived repeated retroposons in the genomes of salmonid species have been isolated and characterized. These three families differ in sequence, but all are derived from a tRNA(Lys) or from a tRNA species structurally related to tRNA(Lys). The salmon Sma I family is present in the genomes of two species of the genus Oncorhynchus but not in other species, including five other species of the same genus. The charr Fok I family is present only in four species and subspecies of the genus Salvelinus. The third family, the salmonid Hpa I family, appears to be present in all salmonid species but is not present in species that are not members of the Salmonidae. Thus, the genome of proto-Salmonidae was originally shaped by amplification and dispersion of the salmonid Hpa I family and then reshaped by amplification of the Sma I and Fok I families in the more recently evolved species of salmon and charr, respectively. We speculate that amplification and dispersion of retroposons may have played a role in salmonid speciation.

Animals↗
PubMed1991

Nucleotide sequences of two genomic DNAs encoding peroxidase of Arabidopsis thaliana.

The peroxidase (EC 1.11.1.7)-encoding gene of Arabidopsis thaliana was screened from a genomic library using a cDNA encoding a neutral isozyme of horseradish, Armoracia rusticana, peroxidase (HRP) as a probe, and two positive clones were isolated. From the comparison with the sequences of the HRP-encoding genes, we concluded that two clones contained peroxidase-encoding genes, and they were named prxCa and prxEa. Both genes consisted of four exons and three introns; the introns had consensus nucleotides, GT and AG, at the 5' and 3' ends, respectively. The lengths of each putative exon of the prxEa gene were the same as those of the HRP-basic-isozyme-encoding gene, prxC3, and coded for 349 amino acids (aa) with a sequence homology of 89% to that encoded by prxC3. The prxCa gene was very close to the HRP-neutral-isozyme-encoding gene, prxC1b, and coded for 354 aa with 91% homology to that encoded by prxC1b. The aa sequence homology was 64% between the two peroxidases encoded by prxCa and prxEa.

Amino Acid Sequence↗
PubMed1991

Comparative studies of decay-accelerating factor and HLA-DR within the CD8-brightly positive population.

Decay-accelerating factor (DAF) is a membrane protein that inhibits C3 convertase activity of autologous complement at the cell surface. We found that DAF+ cells and DAF- (DAFlow, if any) cells are clearly separated from each other among CD8-brightly positive (CD8bright) cells. Using three-color fluorescence flow cytometry, we found that whereas the CD8bright DAF- population express HLA-DR (class II major histocompatibility complex antigens, and an activated T cell marker), the CD8bright DAF+ population does not. Therefore, among the CD8bright T cells, DAF and HLA-DR are mutually exclusive. In addition, the CD8bright DAF+ population proliferates in the presence of recombinant interleukin 2 (rIL2) while the CD8bright DAF- population does not. After a 4-day cultivation of peripheral blood lymphocytes in the presence of rIL2, expression of HLA-DR increased in the CD8bright DAF- population and expression of IL 2Rp55 (alpha chain, the receptor for IL2, and a marker of T cell activation) occurred in the CD8bright DAF+ population. Furthermore, C3 deposition occurred in the CD8bright HLA-DR+ population which lacks DAF when lymphocytes, that had been cultured for 3 days in the presence of rIL2, were incubated with fresh autologous serum. This result suggests that the absence of DAF on CD8bright HLA-DR+ T cells might play a role in permitting complement reaction on the cells in vivo and may be related to the regulation of T cell activation.

Adult↗
PubMed1991

Distribution of the salmonid Hpa 1 family in the salmonid species demonstrated by in vitro runoff transcription assay of total genomic DNA: a procedure to estimate repetitive frequency and sequence divergence of a certain repetitive family with a few known sequences.

An in vitro runoff transcription assay of total genomic DNA was developed. As an example of use of this assay, analysis of a highly repetitive sequence in the cherry salmon (Oncorhynchus masou) is described. Total genomic DNA of the cherry salmon was completely digested with Hpa 1, whose site is known to be in the tRNA-unrelated region of the cherry salmon Hpa 1 family. On transcription of the digested DNA in a HeLa cell extract, a discrete-sized RNA of about 100 nucleotides, constituting 70% of the transcripts, was produced, whereas on transcription of the undigested total DNA, only smeared RNA was obtained. In a fingerprint, the oligonucleotides of the discrete transcript from the digested total DNA were very distinct and exactly corresponded to those of a transcript from an Hpa 1 digest of a cloned DNA, but with few extra oligonucleotides. These results showed that the cherry salmon Hpa 1 family constitutes a major repetitive family in the genome of the cherry salmon. For determination of the distribution of the salmonid Hpa 1 family in other salmonid species, the same analysis was applied to DNAs from the chum salmon (Onchorhynchus keta), brown trout (Salmo trutta), Japanese common charr (Salvelinus leucomaenis pluvius), and Japanese huchen (Hucho perryi). The results showed that the salmonid Hpa 1 family is widespread in the genomes of salmonid species. A method and equations are also presented for estimating the relationship between the ratio of a given repetitive family to all the Pol III genes and its average sequence divergence by calculating the molar ratio of the runoff transcript to all the in vitro Pol III transcripts.

Animals↗
PubMed1991

SINEs.

SINEs with internal promoters for RNA polymerase III are ubiquitous in the genomes of the animal kingdom, including invertebrates. Although the human Alu family, and related families, originates from 7SL RNA, all other SINEs originate from tRNA. SINEs have been amplified many times, altered in genomic organization and fixed in the population at certain stages of evolution. They can therefore be regarded as time-landmarks of evolution. It is proposed that both population genetics and molecular biology are required for understanding the expansion of SINEs.

Animal Population Groups↗
PubMed1991

A novel anti-ENA antibody in sera of patients with childhood idiopathic thrombocytopenic purpura.

Circulating antibodies against certain extractable nuclear antigens (ENA) have been shown to have diagnostic and prognostic importance in connective tissue diseases. We described here an antibody against ENA found in the sera of patients with idiopathic thrombocytopenic purpura (ITP). The antigen, tentatively called WK according to the patients' initials, was distinct from U1 RNP/Sm, SSA/SSB, Scl-70, PCNA, PM-Scl, Jo-1, and Ku by immunodiffusion. On immunoblotting, the anti-WK serum recognized polypeptides of 99 kd, 98 kd, and 96 kd in rabbit thymus extracts and a 99 kd polypeptide in KB cell extracts. The anti-WK antibody was detected in the sera of 2 out of 360 ANA positive patients, both children with clinical features of ITP. One patient developed systemic lupus erythematosus eight years after the onset of ITP.

Antibodies, Antinuclear↗
PubMed1991

Localization of 20-kD homologous restriction factor (HRF20) in diseased human glomeruli. An immunofluorescence study.

The 20-kD homologous restriction factor (HRF20), which is identical to CD59, is a membrane-associated protein which inhibits the reaction of C9 to form membrane attack complex (MAC) of homologous complements. In various human glomerular diseases deposition of complement components is frequently seen and MAC is reported to associate with immune deposits. Using a specific monoclonal antibody, 1F5, against HRF20, we attempted to study the localization of HRF20 in human glomerulonephritides and to compare the localization of HRF20 with those of immune deposits and MAC. The frozen sections of kidney specimens were fixed in acetone at room temperature before staining. In normal kidneys and kidney specimens from the patients with minimal change nephrotic syndrome, membranous nephropathy, and IgA nephropathy, HRF20 was strongly localized in the peritubular capillaries and along Bowman's capsules. A weaker but well-defined staining was obtained in the mesangial area and faint staining was seen along the glomerular capillary walls. In contrast, glomerular capillary walls were rather strongly stained in the cases with diffuse lupus nephritis which had subendothelial dense deposits. These data suggest that HRF20 (CD59) is present in the human glomeruli and its expression is enhanced under certain conditions such as lupus nephritis.

Antigens, Differentiation↗
PubMed1991

Temperature-regulated expression of invasion genes in Shigella flexneri is controlled through the transcriptional activation of the virB gene on the large plasmid.

The invasion phenotype of shigellae is subject to thermoregulation that is known to be expressed through activation of some invasion (inv) genes such as ipaB, ipaC, and ipaD encoded by the large virulence plasmid of Shigella flexneri. The expression of ipa genes is regulated positively by virF through the activation of virB on the plasmid. To identify the mediator for the thermoregulation of the large plasmid, we have studied the effect of temperature on the transcription of virF and virB genes and ipa and the other two inv operons. The results showed that transcription of virB was affected by temperature more strictly than that of virF. Analysis of the mRNA level of virB at different levels of virF transcription indicated that virB transcription depended upon both temperature and virF. On the other hand, transcriptions of ipa and the other two inv operons depended on the activation of virB transcription but not on temperature. By inducing virB transcription from a tac promoter fused with the virB region, invasion ability was restored to a virF-deletion mutant at 30 degrees C as well as at 37 degrees C. By using conditions in which the temperature-dependent expression of the invasion phenotype was circumvented by the induction of virB transcription, intercellular spreading ability in a virF+, virB::Tn5 strain was shown to be expressed even at 30 degrees C. These results suggest that the virB transcription stage is the main target for the thermoregulation.

Blotting, Northern↗
PubMed1991

Virulence-associated chromosomal loci of Shigella flexneri identified by random Tn5 insertion mutagenesis.

Shigellae are the causative agents of bacillary dysentery and are capable of invading epithelial cells, multiplying therein and spreading into adjacent cells. To identify genes on the chromosome associated with the virulence phenotype, 9114 independent Tn5 insertion mutants were isolated in a virulent strain of Shigella flexneri. By using an in vitro assay for intercellular spread or an animal infection model, the Serény test, 50 chromosomal Tn5 mutants with reduced virulence were identified. The 50 mutants were characterized with respect to their virulence phenotypes, including three different mutations that affect invasion of epithelial cells, bacterial metabolism and structure of lipopolysaccharide. Mutants with reduced invasive ability were further characterized and it was found that two of them had decreased levels of IpaB, C and D antigens as well as the mRNA for the ipaBCD operon encoded by the large virulence plasmid, suggesting that positive regulatory elements for the ipaBCD operon are encoded by the chromosome. Assignment of the 50 Tn5 insertions of the mutants to the 19 NotI restriction fragments of the chromosomal DNA has permitted the identification of at least nine virulence-associated chromosomal loci.

Animals↗
PubMed1991

Construction of a physical map of the chromosome of Shigella flexneri 2a and the direct assignment of nine virulence-associated loci identified by Tn5 insertions.

To establish the molecular basis of the chromosomal virulence genes of Shigella flexneri 2a (YSH6000), a Notl restriction map of the chromosome was constructed by exploiting Notl-linking clones, partial Notl digestion and DNA probes from various genes of Escherichia coli K-12. The map revealed at least three local differences in the placements of genes between YSH6000 and E. coli K-12. Using the additional Notl sites introduced by Tn5 insertion, nine virulence loci identified previously by random Tn5 insertions were physically mapped on the chromosome. To demonstrate the versatility of the Notl map in direct assignment of the virulence loci tagged by Tn5 to a known genetic region in E. coli K-12, the major class of avirulent mutants defective in the core structure of lipopolysaccharide (LPS) was examined for the sites of Tn5 insertions. The two Notl segments created by the Tn5 insertion in the Notl fragment were analysed by Southern blotting with two DNA probes for the 5' and 3' flanking regions of the rfa region, and shown to hybridize separately with each of them, confirming the sites of Tn5 in the rfa locus. This approach will facilitate direct comparison genetically mapped Tn5 insertion mutations of S. flexneri with genes physically determined in E. coli K-12.

Chromosome Mapping↗
PubMed1991

Fukuyama type congenital progressive muscular dystrophy.

Clincopathological features of Fukuyama type congenital muscular dystrophy (FCMD), a combination of brain malformation and muscular dystrophy with facial muscle and CNS involvement and high prevalence in Japan, are reviewed. Evidence of progressive dystrophy, negative correlations between muscle enzyme levels and age and CT numbers of muscle and age, are presented. Skeletal muscle histopathology is reviewed. Febrile illness-induced transient exacerbation of muscle weakness is reported. Characteristic brain malformations, e.g. micropolygyria, other dysgenesis, are reviewed. Their severity correlated with maximal mental and motor function. The etiology and significance of low density areas (LDA) in white matter on CT, possibly reflecting delayed or abnormal myelination, and ventricular dilatation are discussed. Spontaneous LDA improvement makes hydrocephaly unlikely. Ophthalmological differential diagnosis from Santavouri disease and Walker-Warburg syndrome, characterized by visual disturbance/glaucoma and microphthalmia/anterior chamber defects, respectively, is discussed. A single defective gene, manifesting as a metabolic error, may produce CNS and ocular defects as well as muscle degeneration in FCMD.

Brain↗
PubMed1991

Recurrent mucocutaneous lymphocytic infiltration possibly associated with Epstein-Barr virus infection.

A 32-year-old man had a history of recurrent but self-healing necrotizing nodules on the face and oral mucosa. Histologically the lesion was composed of necrotizing foci surrounded with dense CD8+ T lymphocytic infiltration in the dermis. Laboratory examination showed marked blood CD8+ T lymphocytosis with a reversed ratio of CD4+/CD8+ of 0.11. Except for a very high titer of antibodies against Epstein-Barr-virus-associated antigens, no signs of infection were observed.

Adult↗
PubMed1991

[Gastrocystoplasty].

In two female patients with severe radiation cystitis, aged 69 and 62 years, the bladder was augmented by an operationally resected segment of the gastric body. The segment, which was vascularized by the right gastroepiploic vessels, was anastomosed to the dome of the bladder. Both ureters were implanted to the gastric segment in one patient. Convalescence was uneventful. No gastric or urinary complication developed. Eight and two months postoperatively both patients were continent of urine and able to urinate satisfactorily. We believe that a gastric segment is a suitable alternative to an intestinal segment in reconstructing the urinary tract.

Aged↗