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Biomedical subjects

A Oka

Publications and source records attributed to A Oka.

At least 73 records · Page 4Linked to original sources
PubMed1998

The expression of late infantile neuronal ceroid lipofuscinosis (CLN2) gene product in human brains.

We raised polyclonal antibodies against a gene product responsible for late infantile neuronal ceroid lipofuscinosis (CLN2). By Western blotting, all three antisera recognized the CLN2 protein at approximately 49 kDa in human brain homogenates. Immunohistochemistry using the antisera demonstrated the granular labelling in the cytoplasm of cerebral neurons and glial cells. The immunoreactivity on Western blots was absent from the brain of a patient with CLN2. Our results suggest the usefulness of these antibodies for the diagnosis of CLN2, which currently requires demonstration of characteristic ultrastructure by electron microscopy.

Adolescent↗
PubMed1998

Expression of the ataxia-telangiectasia gene (ATM) product in human cerebellar neurons during development.

Ataxia-telangiectasia (A-T) is a hereditary disorder, exhibiting progressive cerebellar ataxia. We investigated the expression of the ATM protein in the human CNS. By western blotting, the ATM protein was detected in the cerebellar cortex, but not in the cerebral cortex, at the late gestational stage. Immunohistochemistry revealed that cerebellar neurons, particularly Purkinje cells, were markedly immunoreactive during late prenatal and early postnatal periods, followed by persistent and moderate reactivity in Purkinje cells. The ATM protein was distributed within the cytoplasm of Purkinje cells, but not within the nuclei. The ATM protein seems to play a role as a cytoplasmic protein in neurons of the cerebellar cortex.

Adolescent↗
PubMed1998

Structural characterization of the virB operon on the hairy-root-inducing plasmid A4.

The hairy-root-inducing plasmid A4 (pRiA4) is capable of conferring tumorigenic symptoms on plants upon infection by its host bacterium, Agrobacterium rhizogenes. The virB operon on pRiA4 has been sequenced and found to be composed of 11 genes, virB1 to virB11, whose products mostly appear to be associated with the cell membrane. A novel structural characteristic is frequent overlappings between the translation termination and initiation codons of adjacent genes. This is indicative of fine tuning of relative translation frequencies for each VirB protein. These results support the view that VirB multisubunit complexes provide facilities for T-DNA transfer at the bacterial cell membrane. The structural organization of the pRiA4 virB operon was essentially identical to that of the previously reported virB operons of tumor-inducing plasmids, pTiC58 and pTiA6, and the corresponding VirB proteins of the three plasmids were extremely homologous to one another. On the basis of the structural similarity of each VirB protein, the phylogenetic relationship among pRiA4, pTiC58, and pTiA6 is discussed.

Bacterial Proteins↗
PubMed1998

Nucleotide sequencing analysis of the 146-kilobase segment around the IkBL and MICA genes at the centromeric end of the HLA class I region.

To elucidate the complete gene structure and to identify new genes involved in the development of HLA class I antigen-associated diseases in the class I region of the human major histocompatibility complex on chromosome 6, a YAC clone (745D12) covering the 146-kb segment around the IkBL and MICA loci was isolated from a YAC library constructed from the B-cell line, BOLETH. A physical map of this region was constructed by isolation of overlapping cosmid clones derived from 745D12. Of these, five contiguous cosmids were chosen for DNA sequencing by the shotgun strategy to give a single contig of 146,601 bp from 2.8 kb telomeric of the IkBL gene to exon 6 of MICA. This region was confirmed to contain five known genes, IkBL, BAT1, MICB, P5-1, and HLA-X (class I fragment), from centromere to telomere, and their exon-intron organizations were determined. The 3.8-1 homologue gene (3.8-1-hom) showing 99.7% identity with the 3.8-1 cDNA clone, which was originally isolated using the 3.8-kb EcoRI fragment between the HLA-54/H and the HLA-G genes, was detected between MICA and MICB and was suggested to represent the cognate 3.8-1 genomic sequence from which the cDNA clone was derived. No evidence for the presence of expressed new genes could be obtained in this region by homology and EST searches or coding and exon prediction analyses. One TA microsatellite repeat spanning 2545 bases with as many as 913 repetitions was found on the centromeric side of the MICA gene and was indicated to be a potential hot spot for genetic recombination. The two segments of approximately 35 kb upstream of the MICA and MICB genes showed high sequence homology (about 85%) to each other, suggesting that segmental genome duplication including the MICA and MICB genes must have occurred during the evolution of the human MHC.

Carrier Proteins↗
PubMed1998

Bax and Bcl-2 expressions predict response to radiotherapy in human cervical cancer.

PURPOSE: The ratio of Bcl-2 to Bax expression determines survival or death following an apoptotic stimulus. In order to establish a new predictor of the outcome of treatment for human cervical carcinoma, we investigated the relationship between the expressions of the Bax and Bcl-2 proteins and the response to radiotherapy after the administration of 10.8 Gy. METHODS: A total of 44 patients with histologically proven carcinoma of the uterine cervix, including three with recurrent cervical stump carcinomas, were treated with definitive radiotherapy. The presence of mutations in exons 5-8 of the p53 gene was analyzed by a single-strand conformation polymorphism analysis and DNA sequencing. RESULTS: Forty patients were found to have wild-type p53, and the remaining four had mutant p53. The Bax and Bcl-2 protein expressions prior to radiotherapy did not correlate with response and survival. However, the Bax and Bcl-2 protein expressions after radiotherapy correlated with both response and survival. Bax-positive tumors showed significantly better responses than the Bax-negative tumors after 10.8 Gy radiation (P = 0.0002). In contrast, the Bcl-2-positive tumors showed significantly poorer responses than the Bcl-2-negative tumors after radiation (P = 0.002). Increased Bax expression after the 10.8 Gy radiotherapy was found to be correlated with good survival (P = 0.04). In contrast, increased Bcl-2 expression after such radiotherapy was correlated with poor survival (P = 0.002). CONCLUSION: The levels of Bax and Bcl-2 expression after 10.8 Gy radiotherapy are useful prognostic markers in patients with human cervical carcinoma.

Adult↗
PubMed1998

A case of parietal lobe epilepsy with distinctive clinical and neuroradiological features.

We present a case of parietal lobe epilepsy, the epileptogenic focus of which was conspicuously demonstrated on magnetoencephalography (MEG). The remarkable fluctuation in the seizure frequency and the presence of atonic seizures were suggestive of atypical partial benign epilepsy of childhood (APBEC). An interictal positron emission tomography (PET) scan performed during the cluster of fits revealed hypermetabolism around the epileptogenic focus, which might be related to the marked tendency of clustering of seizures in this patient.

Electroencephalography↗
PubMed1998

A novel mutation found in an adrenoleukodystrophy patient who underwent bone marrow transplantation.

We identified a novel mutation, L322P, in a patient with X-linked adrenoleukodystrophy (ALD) who underwent bone marrow transplantation (BMT). An identification of the ALD gene mutation enabled us to employ an approach not dependent on the use of radioisotopes for detecting mixed chimerism. This assay could show more than 99.0% of the patient's peripheral white blood cells were replaced by the donor's cells.

Adrenoleukodystrophy↗
PubMed1998

Two-component response regulators from Arabidopsis thaliana contain a putative DNA-binding motif.

An expression sequence tag database of higher plants was screened by in silico profile analysis for response regulators of the two-component regulatory system. Two closely related clones (ARR1 and ARR2), corresponding to one of the extracted candidates, were isolated from Arabidopsis thaliana. The two genes were comparably expressed in all tissues, and at higher levels in the roots. The amino-terminal half of their translation products was highly conserved. This is where a phosphate receiver domain with the landmark aspartate residue and a putative DNA-binding domain were located. Their carboxyl-terminal halves, although less similar to each other, included glutamine-rich and proline-rich regions characteristic of the transcriptional activation domain of eukaryotes. This architecture resembles that of typical bacterial response regulators serving as transcription factors.

Amino Acid Sequence↗
PubMed1998

Twenty-six new polymorphic microsatellite markers around the HLA-B, -C and -E loci in the human MHC class I region.

The human major histocompatibility complex (MHC) class I region is believed to contain a large number of disease-related loci for diseases such as Behçet's disease and psoriasis vulgaris. Although many novel genes have recently been identified in this region, it still appears to be difficult to relate any of these new genes to MHC class I-associated diseases as causative genetic factors. During the course of large-scale genomic sequencing of the human MHC class I region, we identified 262 microsatellite sequences with dinucleotide to pentanucleotide repeats around the HLA-B, -C and HLA-E genes. Of these, 26 microsatellites were investigated for repeat polymorphism using 60 HLA homozygous B-cell lines and 60 healthy random individuals. The average number of alleles at these microsatellite loci was 9.6 with a PIC (polymorphism content value) of 0.69. These new polymorphic microsatellite markers will probably be very useful for precise mapping of disease-related genes within the HLA class I region in linkage analysis. Moreover, they will provide a powerful tool to study recombination events in this region, which contributes to haplotypic diversification.

Cell Line↗
PubMed1998

Molecular cloning and expression in Saccharomyces cerevisiae of tobacco NADPH-cytochrome P450 oxidoreductase cDNA.

We obtained information on the full length tobacco NADPH-cytochrome P450 oxidoreductase (P450 reductase) by a combination of the cDNA clone pCTR1 and the genomic DNA clone pGTR1. The deduced primary structure consisting of 713 amino acid residues contained sequences corresponding to FMN, FAD, and NADPH-binding regions. Based on this information, we prepared the full-length cDNA pFTR of tobacco P450 reductase by RT-PCR and expressed it in the yeast Saccharomyces cerevisiae. The transformed yeast cells carrying pFTR produced the corresponding mRNA and protein, and had increased cytochrome c reductase activity in the microsomes. An in vitro reconstitution system of the yeast microsomal fractions expressed tobacco P450 reductase and rat P450 1A1 showed an increased 7-ethoxycoumarin O-deethylase activity. These results indicated that tobacco P450 reductase expressed in the yeast microsomes coupled with rat P450 1A1 resulting in an increased monooxygenase activity.

Amino Acid Sequence↗
PubMed1998

[Bax and Bcl-2 expression predict response to radiotherapy in human cervical cancer].

To establish a new predictor of the outcome of treatment for human cervical carcinoma, we investigated the relationship between the expression of the Bax and Bcl-2 proteins and the response to radiotherapy after administration of 10.8 Gy. A total of 44 patients with uterine cervical carcinoma were treated with definitive radiotherapy. On univariate analysis, Bax and Bcl-2 protein expression prior to radiotherapy did not correlate with survival. Increased Bax expression after 10.8 Gy correlated with good survival (p = 0.003). In contrast, increased Bcl-2 expression after 10.8 Gy correlated with poor survival (p < 0.0001). On multivariate analysis, Bcl-2 expression after 10.8 Gy of radiation was the most important predictor of treatment outcome. The levels of Bax and Bcl-2 expression after 10.8 Gy of radiotherapy are useful prognostic markers in patients with human cervical carcinoma.

Adenocarcinoma↗
PubMed1997

Induction of cyclo-oxygenase 2 in brains of patients with Down's syndrome and dementia of Alzheimer type: specific localization in affected neurones and axons.

Immunohistochemical and immunoblotting studies with an antibody against cyclo-oxygenase 2 (COX2) were performed in the cerebral cortex of patients with Down's syndrome (DS) and dementia of Alzheimer type (DAT). A high level of COX2 expression was observed in DAT and older DS patients, specifically localized in neurones with neurofibrillary tangles (NFT) and damaged axons. Furthermore, immunohistochemical study of patients with DS of varying age showed that the induction of COX2 correlated well with the appearance of NFT as well as with ageing. These findings demonstrated the induction of COX2 in DAT and DS, which may lead to the production of free radicals and may be causally related to neuronal degeneration.

Adolescent↗
PubMed1997

[Acute necrotizing encephalopathy with horizontal gaze palsy].

Acute necrotizing encephalopathy (ANE) of childhood is a newly proposed disease entity characterized by symmetrically distributed necrotic brain lesions in the thalamus, cerebral white matter, brainstem, and cerebellum. We report a 4-year-old girl with severe psychomotor delay and horizontal gaze palsy as sequelae of ANE at 17 months of age. The computed tomography showed bilaterally symmetrical low density areas in the thalamus and low density areas in the left middle cerebral artery (MCA) region and the posterior cerebral artery (PCA) region. MRI (T 1-weighted) revealed unevenly distributed small low signal intensity areas with scattered high intensity regions in the thalamus bilaterally. The T2-weighted images showed multiple small low intensity areas around high intensity areas, and low signal intensity areas in the left middle cerebral artery (MCA) region and the posterior cerebral artery (PCA) region. In addition to severe psychomotor delay, the patient exhibited a peculiar eye movements. Horizontal ocular movement was impaired, but vertical ocular movement was almost completely normal. As clearly shown by MRI of the brain, the pontine tegmentum, including bilateral abducens nucleus, paramedian pontine reticular formation (PPRF), medial longitudinal fasciculus (MLF), and the facial nerve were affected, but the thalamo-mesencephalic junction, including the rostral interstitial medial longitudinal fasciculus (riMLF) and the nucleus of Cajal, was spared. To our knowledge, this is the first case of ANE associated with this selective ocular movement disorder ever reported. Because of the multiple symmetrical lesions and pons and the asymmetrical lesions of the MCA and PCA regions in the present case, occlusion of a single vessel could not account for the pathology. The pathophysiological mechanism of ANE is unknown. We postulate that some toxic or vasoactive agent caused vasospasm and subsequent breakdown of the blood-brain barrier, especially in the thalamus and pons, resulting in the unique distribution of the lesions and the rare eye movement disorder observed in the present case.

Brain↗
PubMed1996

Are argyrophilic nucleolar organizer regions good prognostic indicators of survival of patients with esophageal cancer with lymph node metastasis?

Argyrophilic nucleolar organizer regions (AgNORs) were evaluated in 95 samples from primary esophageal squamous cell carcinomas and 75 samples from metastatic lymph nodes. The number of AgNORs per nucleus in primary tumors with positive nodes (n=53, 6.1+/-1.8) was greater than that in primary tumors with negative nodes (n=42, 3.8+/-1.1, P<0.001). In 39 of 53 patients with positive nodes, the numbers of AgNORs per nucleus in metastatic lymph nodes were lower than those in primary tumors. The 5-year survival rate of these patients was 23.7%. However, the numbers of AgNORs per nucleus in metastatic lymph nodes were greater than those of primary tumors in 14 of 53 patients with positive nodes, and 11 of these 14 patients died from recurrence of cancer within 3 years after surgery. These observations suggest that the proliferative activity of cancer cells might be suppressed in the regional lymph nodes. However, cancer cells with higher proliferative activity in the regional lymph nodes than in the primary tumors might overcome immunological defenses and subsequent further metastasis might occur.

Aged↗
PubMed1996

Limited operation for gastric cancer in the elderly.

The relationship between operative procedures for treatment of patients with gastric carcinoma and complications was studied with special reference to the age of patients, who were divided into four groups: 50-59 years; 60-69 years; 70-79 years; and over 80 years. Preoperative risk factors that were common in patients over 70 years of age were hypertension and cardiac disease. The selected operative procedures were similar for each age group. However, neither proximal gastrectomy nor reconstruction by jejunal interposition was selected for patients of 80 years and over. In these patients, resection of the neighbouring organs was seldom performed and lymph node dissection was usually limited to the primary and secondary nodes. There was no significant difference in the rate of postoperative complications between groups. Although only limited surgery was performed for patients of 80 years and over, there was no significant difference in age-corrected cumulative survival rate between groups. Therefore, limited resection and/or lymph node dissection may allow safe surgical treatment for patients of 80 years and over with gastric carcinoma, without any negative effect on prognosis.

Age Distribution↗