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Biomedical subjects

K Kurose

Publications and source records attributed to K Kurose.

At least 37 records · Page 2Linked to original sources
PubMed1999

Two target regions of allelic loss on chromosome 9 in urinary-bladder cancer.

Allelic losses on chromosome 9 are common in a wide variety of human tumors; moreover, two predisposing loci for some inherited cancer syndromes, i.e., familial malignant melanoma and Gorlin syndrome, have been identified on this chromosome. To define the location of putative tumor suppressor genes involved in cancer of the urinary bladder, 85 bladder cancers were examined for allelic loss at 18 microsatellite loci on chromosome 9. Correlations were also sought between loss of heterozygosity on chromosome 9 and several clinicopathological parameters. Allelic loss was observed in 54 of the tumors (64%) and deletion mapping identified two target regions; one at an interval on 9p21 flanked by D9S736 and D9S165, and the other at an interval on 9q31-34 flanked by D9S58 and D9S61. No subtle mutation was detected in the PTCH gene which lies in the latter interval. Allelic loss on chromosome 9 was observed frequently in low grade and non-invasive tumors as well as in tumors of more advanced phenotype. Inactivation of tumor suppressor genes lying in either of two regions of common deletion identified on chromosome 9 might affect carcinogenic mechanisms at an early stage of tumor development in the urinary bladder.

Chromosome Mapping↗
PubMed1999

A novel positive regulatory element that enhances hamster CYP2A8 gene expression mediated by xenobiotic responsive element.

CYP2A8 is a major form of cytochrome P-450 inducible by 3-methylcholanthrene in Syrian hamster liver. To identify DNA elements necessary for the transcriptional activation of the CYP2A8 gene, we analyzed the regulatory region of the CYP2A8 gene and conducted transient transfection experiments of CYP2A8-luciferase fusion plasmids in primary cultures of hamster hepatocytes. We analyzed up to -5 kb of the 5'-flanking region and found the region sufficient for the 3-methylcholanthrene-inducible gene expression. This region contained a consensus sequence for xenobiotic responsive element (XRE) between -2366 and -2349, which was shown to be essential for induction of the gene expression. Furthermore, we found a novel positive regulatory element for XRE-mediated gene expression (PREX) located upstream of the XRE. This element is not identified in any genes inducible by 3-methylcholanthrene so far reported. Without PREX, the XRE-mediated promoter activity was enhanced nearly 10-fold, whereas with PREX, the activity was enhanced 20-fold over the basal level. Gel mobility shift assays revealed specific binding of nuclear proteins to PREX. Mutations and deletions of PREX caused a loss of the binding and promoter-enhancing activities, respectively. Moreover, transient expression experiments showed that the enhancing activity of PREX was not observed in Drosophila Schneider's line 2 cells, which were shown to lack the PREX binding proteins.

Animals↗
PubMed1998

A major phenobarbital-inducible P450 isozyme, CYP2A14, in the Chinese hamster liver: purification, characterization, and cDNA cloning.

Phenobarbital, a potent inducer of CYP2B isozyme of cytochrome P450, induces mainly CYP2A but not CYP2B in the Chinese hamster liver. A major isozyme inducible by phenobarbital was purified by column chromatography from Chinese hamster livers. This isozyme, named P450CH2A-2 and designated CYP2A14, had in the reconstituted system high activities of 7-ethoxycoumarin O-deethylase (43 nmol/min/nmol P450) and aflatoxin B1 activation and a moderate activity of testosterone 15alpha-hydroxylase and coumarin 7-hydroxylase. The N-terminal amino acid sequence of the purified protein had a high homology with those of CYP2A proteins. cDNA of this isozyme was analyzed by screening a Chinese hamster liver cDNA library with cDNA of CYP2A1 as a probe, and the obtained clone encoded a protein of 494 amino acids with a calculated molecular mass of 56.4 kDa. The N-terminal amino acid sequence of 20 residues was identical to that derived from the purified protein. The deduced amino acid sequence of the clone had a high identity with most of CYP2A proteins (>65%) and thus was designated CYP2A14. Immunoblot and Northern blot analyses demonstrated that this isozyme was induced markedly by phenobarbital but not with 3-methylcholanthrene and constitutes one of the major components in livers of phenobarbital-treated Chinese hamsters.

Amino Acid Sequence↗
PubMed1998

cDNA cloning and expression of a novel CYP3A from the Syrian hamster, CYP3A31.

A clone, encoding a cytochrome P450 protein consisting of 501 amino acids, was isolated from a cDNA library constructed from mRNA of Syrian hamster liver. The deduced amino acid sequence of this clone showed a high homology (65 to 81%) with other mammalian CYP3As and hence, this novel isozyme was named CYP3A31. By Northern blotting, using an oligonucleotide specific to CYP3A31, the mRNA for this isozyme was shown to be expressed constitutively in liver and induced by treatment with phenobarbital but repressed by 3-methylcholanthrene or dexamethasone treatments. The increase in mRNA expression by phenobarbital and decrease by dexamethasone corresponded to changes in CYP3A protein as analysed by Western blotting. These indicate that CYP3A31 might constitute one of the major CYP3A isozymes in the hamster.

Amino Acid Sequence↗
PubMed1998

Cloning and characterization of Syrian hamster testosterone 7 alpha-hydroxylase, CYP2A9.

We report here the cloning of a cDNA encoding testosterone 7 alpha-hydroxylase in the Syrian hamster, designated CYP2A9. Overlapping clones encoding Syrian hamster CYP2A9 were isolated by screening a liver cDNA library and by performing rapid amplification of cDNA ends polymerase chain reaction on the cDNA library. The sequence of the CYP2A9 cDNA contains an open reading frame of 1482 nucleotides encoding a polypeptide of 493 amino acids with a calculated molecular mass of 56,295 Da. The sequence is flanked by a 5'-untranslated region of 10 bp and a 3'-untranslated region of 178 bp including the poly(A) tail. The deduced amino acid sequence shares significant homology with members of CYP2A subfamily, notably with CYP2A1 and CYP2A12 which have testosterone 7 alpha-hydroxylase activity. We characterized the catalytic activity of CYP2A9 using microsomes obtained by transient expression of its cDNA in transfected COS-7 cells. CYP2A9 was found to hydroxylate testosterone at position 7 alpha. In Syrian hamster livers, a higher level of testosterone 7 alpha-hydroxylase activity as well as the mRNA of CYP2A9 in male than in female was obtained. The testosterone 7 alpha-hydroxylase activity and the mRNA level in liver were both decreased moderately by administration of 3-methylcholanthrene and slightly by administration of phenobarbital. In contrast, in kidney, both 3-methylcholanthrene and phenobarbital significantly decreased the mRNA level. These facts indicate that the regulation of the hamster testosterone 7 alpha-hydroxylase (CYP2A9) expression is different from that of the rat (CYP2A1) and hamster reported previously by other workers.

Amino Acid Sequence↗
PubMed1998

Somatic mutations of the PTEN/MMAC1 gene in fifteen Japanese endometrial cancers: evidence for inactivation of both alleles.

Loss of heterozygosity (LOH) of chromosome 10q is observed in approximately 40% of endometrial cancers. Mutations in PTEN/MMAC1, a gene recently isolated from the 10q23 region, are responsible for two dominantly inherited neoplastic syndromes, Cowden disease and Bannayan-Zonana syndrome. Somatic mutations of this gene have also been detected in sporadic cancers of the brain, prostate and breast. To investigate the potential role of this putative tumor suppressor gene in endometrial carcinogenesis as well, we examined 46 primary endometrial cancers for LOH at the 10q23 region, and for mutations in the entire coding region and exon-intron boundaries of the PTEN/MMAC1 gene. LOH was identified in half of the 38 informative cases, and subtle somatic mutations were detected in 15 tumors (33%). Our results suggest that of the genes studied so far in endometrial carcinomas, PTEN/MMAC1 is the most commonly mutated one, and that inactivation of both copies by allelic loss and/or mutation, a pattern that defines genes as "tumor suppressors," contributes to tumorigenesis in endometrial cancers.

Alleles↗
PubMed1998

Frequent allelic loss at 7p14-15 associated with aggressive histologic types of breast cancer.

We examined 142 primary human breast cancers to determine their patterns of loss of heterozygosity (LOH) at 19 microsatellite markers over the entire length of chromosome 7. Allelic loss at one or more loci on the short arm of chromosome 7 was observed in 37 of the tumors (26%). We found a new target region of allelic loss on 7p between D7S1802 and D7S817 at 7p14-15. LOH on 7p was found more frequently in tumors of the invasive solid tubular and scirrhous type (31 of 87); 36%) than in other less aggressive types (2 of 27; 7%) (P = 0.0047). The results suggest that inactivation of putative tumor suppressor gene(s) located at 7p14-15 may play a role in the development and/or progression of primary breast cancers, particularly those of the invasive solid tubular and scirrhous type. Allelic loss was also found in 56 of 142 tumors on the long arm, and a commonly deleted region was defined between D7S522 and D7S1801 at 7q31.

Breast Neoplasms↗
PubMed1998

Mapping of a new target region of allelic loss to a 2-cM interval at 22q13.1 in primary breast cancer.

Allelic losses on chromosome arm 22q are frequently observed in human meningiomas and in carcinomas of the colon, ovary, and breast. Among 140 primary breast cancers we examined for loss of heterozygosity (LOH) at 16 polymorphic loci on the long arm of chromosome 22, 56 (40%) showed LOH for at least one locus. Eleven of these tumors had retained heterozygosity for markers proximal to the NF2 locus but showed LOH for markers distal to NF2. Deletion mapping indicated a new common region of deletion, 2-cM in extent, at q13.1 between Interleukin 2 receptor beta (IL2RB) and D22S279. Our results raise the possibility that one or more tumor suppressor genes associated with breast cancer may exist at 22q13.1. Comparison of these results with clinicohistological data indicated that allelic losses on 22q tend to occur more frequently in tumors of malignant histological types.

Alleles↗
PubMed1997

Placebo-controlled trial of vaccination with hepatitis B virus surface antigen in hepatitis B virus transgenic mice.

BACKGROUND/AIMS: Treatment of hepatitis B virus carriers by vaccine containing hepatitis B surface antigen with Pre-S protein and HBsAg/ anti-HBs complex has been reported and these studies have constituted a new and promising concept for the treatment of HBV-carriers. The present communication, a placebo-controlled trial of vaccination in HBV-transgenic mice, was designed to examine the impact of vaccination using a high dose of HBsAg for a duration of 12 months to achieve further insights about the dose, duration and effectiveness of vaccine therapy. Another aim of this study was to analyse the mechanism underlying the antiviral and immunomodulatory potentiality of vaccine therapy in HBV-transgenic mice. METHODS: HBV-transgenic mice positive for HBV DNA, hepatitis B surface antigen and hepatitis B e antigen in sera received either HBV-vaccine containing HBsAg in complete Freund's adjuvant (CFA), intraperitoneally, once a month for 12 consecutive months (vaccine recipients), or only CFA, intraperitoneally once in a month for 12 consecutive months (placebo recipients). Thirty-two vaccine-recipient and 16 placebo-recipient HBV-transgenic mice were injected, checked and followed on a monthly basis for the entire duration of 12 months. RESULTS: Of the 32 transgenic mice from the vaccine-recipient group, 25 became completely negative for HBsAg and 30 for HBeAg. Five mice developed anti-HBs in sera after the observation period of 12 months. Semiquantitative estimation of HBV DNA by polymerase chain reaction showed that vaccination resulted in a decrease of HBV DNA in sera. Placebo-recipient transgenic mice did not show any significant change in the titres of HBV markers after receiving 12 monthly injections of CFA. Interleukin-2 could be detected in sera from vaccine-recipient transgenic mice, but not in placebo-recipient transgenic mice. CONCLUSIONS: Vaccination with a high dose of HBsAg in adjuvant over a long period had a significant antiviral as well as immunomodulatory potential in HBV-transgenic mice. This inspires optimism that vaccine alone or in combination with antiviral agents can be used successfully for the treatment of human HBV-carriers.

Adjuvants, Immunologic↗
PubMed1997

Production of antibody to hepatitis B surface antigen (anti-HBs) by murine hepatitis B virus carriers: neonatal tolerance versus antigen presentation by dendritic cells.

The inability of hepatitis B virus (HBV) transgenic mice, which express abundant hepatitis B surface antigen (HBsAg) in sera from the neonatal period onwards, to produce antibody to HBsAg (anti-HBs) is considered to be due to defective function of lymphocytes. The defective function is thought to result from neonatal tolerance because antigenic challenge during the neonatal period is considered to be a tolerogenic event rather than an immunogenic one. However, a series of mixed culture experiments in vitro showed that lymphocytes taken from transgenic mice that had been injected with HBsAg in complete Freund's adjuvant (CFA) constitutively produced anti-HBs when cultured with dendritic cells from age-, sex- and major histocompatibility complex (MHC)-matched normal mice, but not when cultured with dendritic cells from transgenic mice. The expression of major histocompatibility complex (MHC) class II and B 7.2 (CD86) antigens on dendritic cells was significantly lower in transgenic mice compared with the same from the normal mice (P < 0.05). Treatment of transgenic mice with interferon-gamma (IFN-gamma) resulted in up-regulation of MHC class II on dendritic cells, and lymphocytes from HBsAg-injected transgenic mice produced anti-HBs in vitro when cultured with dendritic cells from IFN-gamma-treated transgenic mice, but not when cultured with the dendritic cells from untreated transgenic mice. These experiments have shown that defective function of antigen-presenting cells (APC), not immunogenic tolerance, is responsible for the inability of murine HBV-carriers to produce anti-HBs. Production of anti-HBs by lymphocytes from HBsAg-injected transgenic mice in the presence of dendritic cells that express higher levels of MHC class II and CD86 antigens has inspired optimism that a more effective vaccine therapy can be developed for chronic HBV-carriers, injecting vaccine containing HBsAg with modulator(s) of APC function of dendritic cells.

Animals↗
PubMed1997

Clinicopathological characteristics of the focal and segmental form of idiopathic membranous nephropathy: comparison with the typical form of this disease.

Although idiopathic membranous nephropathy (IMN) is thought to represent a diffuse glomerulopathy, it was found that three of 31 children histologically diagnosed as IMN showed focal and segmental deposition of immunoglobulin G (IgG) and C3 on the glomerular capillary walls. The present study attempted to comparatively investigate clinical and pathological features of the diffuse group and the focal segmental group in 31 IMN children. Immunofluorescence study revealed that 28 of 31 IMN exhibited diffuse granular deposition of IgG along glomerular capillary walls. In contrast, focal and segmental deposition of IgG and C3 was noted in three children with IMN. In addition, focal and segmental electron-dense deposits were identified in these cases. In two children of the focal segmental group, immunofluorescent patterns of IgG deposition were unchanged even at the second biopsy. The focal segmental form of IMN tended to occur in younger children than diffuse IMN. However, other clinical parameters such as the range of proteinuria, hematuria, serum albumin and prognosis did not show any significant differences between both groups. Electrophoretic profiles of urinary proteins on sodium dodecylsulfate-polyacrylamide gel electrophoresis were not different between both groups. It is proposed that the focal segmental form of IMN may have a distinctive glomerulopathy from the typical form of IMN.

Child, Preschool↗
PubMed1996

Microfluorometric study of nuclear DNA in normal human epidermis.

Quantitative and qualitative changes of nuclear DNA were analyzed by microfluorometry in normal human epidermis during terminal differentiation. Normal human epidermis from five healthy volunteers was separated by an EDTA-trypsin method and fractionated by Percoll density gradient. Staining was carried out with either Feulgen reaction, Acridine Orange or 4'-6-diamidino-2-phenylindole (DAPI). When the cells with lower density (granular layer cells) were stained with Acridine Orange or DAPI, the greatest population was found at lower value of DNA than that in the cells stained with Feulgen reaction. After thermal denaturation procedure, a ratio of double-stranded DNA to single-stranded DNA was highest in the cells with lower density. These results seem to suggest the qualitative and quantitative changes of nuclear DNA during terminal differentiation of human epidermal keratinocytes.

Acridine Orange↗
PubMed1996

Response to interferon in chronic hepatitis C due to mixed genotype infection.

We examined the response to interferon (IFN) in patients with chronic hepatitis C (CHC) due to two different genotypes of hepatitis C virus (HCV) infection. Among 64 CHC patients studied, one (2%) had HCV-RNA genotype I, 36 (56%) had genotype II, 19 (30%) had genotype III, 2 (3%) had genotype IV and 6 (9%) had both genotypes II and III. There was no significant difference in age, sex, history of blood transfusion and liver histology among patients with genotypes II, III and II + III. The HCV-RNA titre of genotype II patients was significantly higher than that of genotype III patients (P < 0.05). However, there was no significant difference in the HCV-RNA titre between genotype II + III and the other groups. The complete response rate achieved with IFN therapy was significantly higher in genotype III patients (74%) than in genotype II patients (17%; P < 0.01). Of the six patients with genotype II + III, a complete response to IFN was only achieved by two patients (33%), both of whom had a low HCV-RNA titre ( < or = 10(4.5) copies/mL) and HCV serotype 2. The remaining four patients had HCV serotype 1 and three of the patients had a high HCV-RNA titre ( > or = 10(5) copies/mL). The HCV genotype III was lost in two patients after IFN therapy. These data suggest that HCV-RNA titre and HCV serotype are important factors for predicting the efficacy of IFN therapy in patients with mixed genotype infection and show direct evidence of higher susceptibility towards CHC of patients with genotype III than genotype II.

Adolescent↗
PubMed1996

Serum tumor necrosis factor in mesangial IgA glomerulonephritis with macroscopic hematuria in children.

Tumor necrosis factor (TNF)-alpha and interferon (INF)-gamma levels were measured in the sera obtained from 29 patients with IgA glomerulonephritis (IgA GN), 8 patients with minimal change nephrotic syndrome (MCNS) and 12 patients with upper respiratory tract infection (URI) without renal diseases in children. The serum TNF-alpha level of IgA GN was 123.0 +/- 175.4 pg/ml, MCNS was 4.9 +/- 4.0 pg/ml and URI was 10.5 +/- 4.5 pg/ml respectively. The serum TNF-alpha level of IgA GN was significantly higher than those of MCNS and URI. The serum TNF-alpha level of URI was on the high trend compared with that of MCNS, but was not statistically significant. Although the TNF-alpha level was related to mesangial cell proliferation in patients with IgA GN, it was unrelated to the grade of mesangial matrix expansion and magnitude of proteinuria. In 17 patients with IgA GN having macroscopic hematuria, the serum TNF-alpha level was 190.5 +/- 201.6 pg/ml, and in other IgA GN patients with microscopic hematuria it was 37.4 +/- 75.7 pg/ml. The serum TNF-alpha level of IgA GN with macroscopic hematuria was significantly higher than that with microscopic hematuria. In 6 patients with IgA GN with macroscopic hematuria, the serum TNF-alpha level was significantly decreased after macroscopic hematuria disappeared. The mean serum IFN-gamma level of IgA GN was 0.3 +/- 0.6 IU/ml, and MCNS was not detectable. Although the serum IFN-gamma level was related to mesangial cell proliferation in patients with IgA GN, it was unrelated to magnitude of proteinuria, the grade of mesangial matrix expansion and also the presence or absence of macroscopic hematuria. We suggest that macroscopic hematuria of IgA GN was closely related to the serum TNF-alpha level.

Adolescent↗
PubMed1996

Okadaic acid potentiates 3-methylcholanthrene-induced CYP2A8 gene expression in primary cultures of Syrian hamster hepatocytes: possible involvement of activator protein-1.

In Syrian hamster liver, treatment with 3-methylcholanthrene (3-MC) markedly induces an isozyme of cytochrome P450 (CYP), CYP2A8. To elucidate the mechanism of this induction, we studied the effect of okadaic acid (OA), an inhibitor of serine threonine protein phosphatases 1 and 2A, on 3-MC-induced CYP2A8 expression in primary cultures of Syrian hamster hepatocytes. The addition of OA to the cultured hepatocytes at a concentration of 1 nM potentiated 3-MC- (0.1 and 1 microM) induced expression of mRNA and protein of CYP2A8 and its associated coumarin 7-hydroxylase activity. In addition, OA not only induced c-fos and jun-D mRNA, components of transcription factor activator protein-1 (AP-1), with an increase in AP-1 binding activity in the nucleus, but also activated AP-1-dependent gene transcription in the hepatocytes. The dose-dependent effect of OA on 3-MC-induced CYP2A8 expression corresponded to that of OA on c-fos and jun-D mRNA induction and on the activation of AP-1-dependent gene transcription. The expression of c-fos and jun-D mRNA induced by OA preceded the expression of CYP2A8 mRNA potentiated by co-treatment with 3-MC and OA. Treatment with anisomycin and cycloheximide also potentiated 0.1 microM 3-MC-induced coumarin 7-hydroxylase activity, induced c-fos and jun-D mRNA expression, and activated AP-1-dependent gene transcription in the hepatocytes. Furthermore, 3-MC-induced CYP2A8 expression was potentiated in the hepatocytes transfected with c-Jun expression plasmid. These results suggest that AP-1, inducible by serine threonine protein kinase, may be one of the components of the signal transduction system from 3-MC to CYP2A8 gene expression.

Animals↗
PubMed1996

Serum from normal elderly individuals contains anti-basement membrane zone antibodies.

BACKGROUND: Bullous pemphigoid is an autoimmune bullous disease with circulating anti-basement membrane zone antibodies, and it commonly affects elderly individuals; however, the reasons for the late onset of the disease are unclear. DESIGN: The anti-basement membrane zone antibodies in serum samples from normal elderly subjects were compared with those in serum samples from normal young subjects. PARTICIPANTS: Serum samples from 32 elderly and 28 young normal individuals and 10 patients with bullous pemphigoid were used. INTERVENTIONS: Indirect immunofluorescence against guinea pig esophagus or human salt-split epidermis and immunoblotting against human and guinea pig epidermis were performed. RESULTS: Serum samples from young individuals were devoid of anti-basement membrane zone antibodies against guinea pig esophagus and human salt-split epidermis. Among 32 serum samples from elderly patients, 6 cases (19%) were positive for anti-basement membrane zone antibody for guinea pig esophagus, and in those the titers were 10 in 3 cases and 40, 80, and 320 in the others. One case was positive against human split epidermis at a titer of 10. An immunoblotting analysis showed that the antigenicity of the 230-kd and 180-kd bullous pemphigoid antigen from guinea pig epidermal extract was similar to that of human epidermal extract; however, the molecular weight was slightly different. The 4 cases of elderly serum that recognized guinea pig esophagus basement membrane zone showed positivity with the 230-kd peptide in the guinea pig epidermal extract; however, they were negative with the human epidermal extracts. Direct immunofluorescence observation of these cases showed that deposition of IgG or C3 was not present in cryostat sections from flexor arm surfaces. CONCLUSIONS: The serum samples from elderly subjects possessed a relatively high incidence of anti-basement membrane zone antibodies detectable with guinea pig esophagus as substrate. This observation of a specific immune defect in elderly individuals might explain why they are more susceptible to developing bullous pemphigoid.

Adult↗
PubMed1995

RNA polymerase III dependence of the human L1 promoter and possible participation of the RNA polymerase II factor YY1 in the RNA polymerase III transcription system.

From the general views of the eukaryotic transcription systems, L1 (or L1-like) retrotransposons that encode some proteins are unusual. L1, unlike other protein-coding elements, is transcribed through an internal promoter. And the L1 internal promoter, unlike other internal promoters, is thought to be RNA polymerase II (pol II) dependent, because the L1 transcript has a large size (approximately 6 kb), protein coding capacity and a 3' terminal polyadenylation signal followed by a poly(A) tail, and also because transcription from the promoter of Drosophila L1-like element jockey was highly sensitive to alpha-amanitin. However, our in vitro transcription study reveals that transcription from the human L1 promoter is highly sensitive to tagetitoxin, a selective inhibitor of RNA polymerase III (pol III), but insensitive to 1 micrograms/ml of alpha-amanitin, indicating that the human L1 promoter is pol III-dependent. The pol III dependence is further supported by our observation that L1 and pol III-dependent tRNA gene promoters share a common nuclear factor YY1. There is evidence that YY1 is also a pol II transcription factor. We thus propose that YY1 is a possible member of the pol III transcription system.

Base Sequence↗