PubMed Health⌕ Search

Biomedical subjects

Masao Yamada

Publications and source records attributed to Masao Yamada.

At least 37 records · Page 2Linked to original sources
PubMed2005

Catalase deficiency renders remnant kidneys more susceptible to oxidant tissue injury and renal fibrosis in mice.

BACKGROUND: Catalase is one of the important antioxidant enzymes regulating the levels of intracellular hydrogen peroxide and hydroxyl radical. The effect of catalase deficiency on progressive renal fibrosis has not been fully elucidated. METHODS: Homozygous acatalasemic mutant mice (C3H/AnLCs(b)Cs(b)) and control wild-type mice (C3H/AnLCs(a)Cs(a)) were subjected to 5/6 nephrectomy. The functional and morphological alterations of the remnant kidneys, including tubulointerstitial fibrosis, epithelial to mesenchymal transition (EMT), peroxidation, antioxidant enzyme activity, and gene expression of EMT-related molecules were compared between the two groups at 6, 12, and 18 weeks after 5/6 nephrectomy. RESULTS: The 5/6 nephrectomy resulted in albuminuria, decreased renal function, and tubulointerstitial fibrosis with accumulation of type I and type IV collagens in the remnant kidneys of both mouse groups. However, the degree of these changes was significantly higher in acatalasemic mice after 5/6 nephrectomy as compared with wild-type mice until week 18. EMT, a crucial phenotypic alteration of tubular epithelial cells, was observed in acatalasemic mice by electron microscopy and was associated with upregulation of EMT-related alpha-smooth muscle actin (alpha-SMA), transforming growth factor-beta1 (TGF-beta1), connective tissue growth factor (CTGF), and fibroblast specific protein-1 (FSP-1) gene expression. Significant increases in the tubulointerstitial deposition of lipid peroxidation products, including 4-hydroxy-2-nonenal and urinary excretion of 8-hydroxy-2'- deoxyguanosine were observed in the acatalasemic mice after 5/6 nephrectomy as compared with the wild-type mice. Glomerular sclerosis developed after tubulointerstitial injury in acatalasemic mice. The level of catalase activity remained low in the remnant kidneys of acatalasemic mice until week 18 without compensatory up-regulation of glutathione peroxidase or superoxide dismutase (SOD) activity. Finally, supplementation of a SOD mimetic tempol did not prevent peroxidation and tubulointerstitial fibrosis in the acatalasemic remnant kidneys. CONCLUSION: These findings indicate that acatalasemia exacerbates renal oxidant tissue injury and sensitizes remnant kidneys to EMT and progressive renal fibrosis. This study suggests a central role for catalase in the defense against oxidant-mediated renal fibrosis.

Albuminuria↗
PubMed2004

(2,7-Disubstituted-1,8-biphenylenedioxy)bis(dimethylaluminum) as bidentate organoaluminum Lewis acids: elucidation and synthetic Utility of the double electrophilic activation phenomenon.

A series of (2,7-disubstituted-1,8-biphenylenedioxy)bis(dimethylaluminum) (2) has been readily prepared in situ by treatment of the requisite 2,7-disubstituted-1,8-biphenylenediol (1) with Me3Al (2 equiv) in CH2Cl2 at room temperature; this primarily relies on the successful establishment of a new synthetic procedure of 1 starting from inexpensive m-anisidine. Evaluation of 2 as a bidentate organoaluminum Lewis acid has been performed by the reduction of ketonic substrates using Bu3SnH as a hydride source in comparison to the conventional monodentate Lewis acid dimethylaluminum 2,6-xylenoxide (11), uncovering the significantly high activation ability of 2 toward carbonyl. Particularly, (2,7-dimethyl-1,8-biphenylenedioxy)bis(dimethylaluminum) (2a) exerted the highest reactivity, which has also been emphasized in the Mukaiyama aldol reaction. The structure of the bidentate Lewis acid 2 was unambiguously determined by single-crystal X-ray diffraction analysis of 2g possessing a bulky 3,5-di-tert-butylphenyl substituent, revealing the rigid dimeric assembly in the solid state. The double electrophilic activation of carbonyl substrate by 2a has been supported by low-temperature 13C NMR analysis as well as theoretical study using the Gaussian 98 program. Moreover, unique stereoselectivity has been observed in the 2a-promoted Mukaiyama Michael addition, and highly chemoselective functionalization of carbonyl compounds in the presence of their acetal counterparts has been realized using 2a. Finally, the effectiveness of 2a for the activation of ether functionality has been demonstrated in the Claisen rearrangement of allyl vinyl ethers.

Journal Article↗
PubMed2004

Identification of a novel polymorphism involving a CGG repeat in the PTCH gene and a genome-wide screening of CGG-containing genes.

Mutations in the human homologue of the Drosophila patched gene (PTCH) are responsible for the hereditary disorder called nevoid basal cell carcinoma syndrome (NBCCS). PTCH has a CGG triplet repeat located 4 bp upstream of the first methionine codon. Here we report a novel polymorphism involving the number of the CGG-repeat. The major allele (86.3%) contained a repeat size of seven, whereas the minor allele contained eight. No significant difference in the distributions of genotypes was observed between normal and NBCCS individuals. However, when the repeat was inserted between a heterologous promoter and the luciferase gene, the longer repeats tended to induce higher luciferase activities, suggesting that the repeat length potentially affects the levels of gene expression. A genome-wide screening revealed that 68 and 146 genes contained a CGG/CCG repeat in the coding region and in the 5'-untranslated region (5'-UTR), respectively. None of the genes had this repeat in 3'-UTR. Interestingly, the number of genes with a CGG repeat in the 5'-UTR was significantly higher than that with a CCG repeat in the 5'-UTR. The localization of a CGG/CCG repeat in PTCH is quite unique in that only four other genes have been found in which the repeat is localized up to 4 bp upstream of the first methionine.

Alleles↗
PubMed2004

Construction of unmodified oligonucleotide-based microarrays in the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1: screening of the candidates for circadianly expressed genes.

DNA microarrays with unmodified oligonucleotide probes are a cost-effective and high-performance alternative to cDNA microarrays. We searched every gene in the genome of the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 for 45-mer oligonucleotide probes with optimal nucleotide sequences, and found such probes in 90% of the genes. Using the probes, we constructed a microarray that represented 2,397 genes (95% of total genes). We detected only low signals in the negative control probes whose nucleotide sequences are not contained in the T. elongatus genome, demonstrating that specific hybridization occurred. To evaluate the reliability of the measurements obtained by the oligonucleotide microarray, we performed microarray experiments using RNA samples from two different time points of circadianly synchronized cultures, LL2 (early sub-jective day) and LL14 (early subjective night). Measurements obtained from the two independent microarray hybridizations were highly concordant (correlation coefficient [r] > 0.8). Northern blot analyses of 20 genes confirmed that expression changes detected by the microarrays were correct (r = 0.832). We identified 143 candidate clock-controlled genes whose expression levels at LL2 and LL14 were significantly different. Expression of 69 of them was enhanced at LL14 while expression of the other 74 was enhanced at LL2. The physiological functions of the genes were diverse and included metabolism, translation, transcription, membrane transport, DNA replication and repair, and cell growth and death.

Blotting, Northern↗
PubMed2004

Induction and prevention of virus-associated malignant lymphoma by serial transmission of EBV-related virus from cynomolgus by blood transfusion in rabbits.

Epstein-Barr virus (EBV)-related herpesvirus (Si-IIA-EBV) was serially transmitted for 3 passages from rabbit to rabbit of the opposite sex by blood transfusion, which subsequently induced virus-associated rabbit lymphomas. The virus could be transmitted by transfusion with 15-20 ml of whole blood (7/7) or irradiated blood (1/6) from the EBV-related virus-infected rabbits, but there was no transmission with transfusion of cell-free plasma (0/6) from the infected rabbits. Passive anti-EBV-VCA IgG (x 20 approximately x 10) titers decreased during the first 1-2 weeks in the transfused rabbits. The virus-transmitted rabbits showed a gradual increase in antibody titers ranging from peak titers of x 640 to x 2560 after 3 weeks of transfusion. The recipient origin of malignant lymphoma that developed in the first rabbit transfused by infected blood was confirmed by chromosomal analysis. This rabbit model thus shows that EBV-related herpesvirus is serially transmissible by blood transfusion and that transmission can not be completely prevented by irradiation of blood, but removal of blood cells is the best way to prevent transmission of EBV-related virus. Therefore, this animal model provides a convenient in vivo system for studies of the prevention and therapy of transfusion-related transmission of EBV and EBV-associated lymphoproliferative diseases in immunocompromised human beings.

Animals↗
PubMed2003

Gorlin syndrome with ulcerative colitis in a Japanese girl.

We present the case of a 14-year-old Japanese girl who had both Gorlin syndrome and ulcerative colitis. She had complained of blood stools for 6 months and severe scoliosis from her infancy. Physical examination revealed multiple nevi, palmar and plantar pits, jaw cysts, and calcification of the falx cerebri, leading to the diagnosis of Gorlin syndrome. Total colonoscopy revealed an edematous and spotty bleeding mucosa extending from the anus to the transverse colon. Histological examination was also compatible with ulcerative colitis. Thus, we diagnosed her as having Gorlin syndrome with ulcerative colitis. Gene analysis revealed a mutation, 1247InsT, in the human patched gene (PTCH), resulting in the truncation of PTCH protein. Since Gorlin syndrome and ulcerative colitis are rare disorders in childhood, this association is interesting, suggesting a correlation between the hedgehog signaling and intestinal disorders.

Adolescent↗
PubMed2003

Genomic structure and alternative splicing of the insulin receptor tyrosine kinase substrate of 53-kDa protein.

Insulin receptor tyrosine kinase substrate of 53-kDa protein (IRSp53) is now known to be a key factor in cytoskeleton reorganization. The human IRSp53 was identified as a binding partner with DRPLA protein, a product of the gene responsible for a neurodegenerative disorder, dentatorubral pallidoluysian atrophy, as well as a binding partner with brain-specific angiogenesis inhibitor 1. Previous studies identified at least four isoforms (L-, M-, S- and T-forms) in human, where 511 amino acid residues from the N-terminus were identical, followed by unique sequences of 9-41 amino acid residues. As each isoform had a distinct function, the unique sequences at the C-terminus had a vital role in its function. Here we report that these isoforms were indeed generated by alternative splicing, which was established by experimental and computational studies on human and rodent genomes. Previous biochemical reports suggested that rodents may lack one of the isoforms (L-form). This study solved this issue, as a nucleotide substitution occurred at a splice donor site followed by a large deletion in the rodent genome compared with human, which made the generation of the L-form impossible. This study also revealed overlapping of the IRSp53 and AATK genes coded for by complementary strands.

Alternative Splicing↗
PubMed2003

Dentatorubral-pallidoluysian atrophy protein is phosphorylated by c-Jun NH2-terminal kinase.

Dentatorubral-pallidoluysian atrophy (DRPLA) is a dominant-inherited neurodegenerative disease characterized by selective cell loss in particular neuronal pathways. This is caused by expansion of CAG repeats in the coding region of the DRPLA gene, and the extended polyglutamine tract (polyQ) confers a toxic activity. It is valuable to characterize disease gene products for elucidation of the mechanism underlying neuron death at specific anatomical areas of the brain. Here, we define the DRPLA protein as a phosphoprotein, and c-Jun NH(2)-terminal kinase (JNK) is one of the major factors involved in its phosphorylation. Endogenous DRPLA protein was serine-phosphorylated. Phosphorylation was demonstrated in a recombinant JNK activation system in vitro and also in overexpressing cells by transfection after the JNK activation with osmotic pressure. One of the phospho-acceptor sites for JNK appearing in the DRPLA sequence was indeed phosphorylated, which was confirmed by a specific antibody raised against the phosphopeptide. Kinetic studies in the JNK recombinant system showed that expanded polyQ slightly reduced the affinity of JNK to the protein. Thus, the abnormal DRPLA protein seems to be slowly phosphorylated in a certain condition of JNK activation in patients. It may delay a process that is essential in keeping neurons alive.

Amino Acid Sequence↗
PubMed2003

Mutations of the PAX6 gene detected in patients with a variety of optic-nerve malformations.

The PAX6 gene is involved in ocular morphogenesis and is expressed in the developing central nervous system and numerous ocular tissues during development. PAX6 mutations have been detected in various ocular anomalies, including aniridia, Peters anomaly, corneal dystrophy, congenital cataracts, and foveal hypoplasia. However, it has not been identified in patients with optic-nerve malformations. Here, we identified novel mutations in eight pedigrees with optic-nerve malformations, including coloboma, morning glory disc anomaly, optic-nerve hypoplasia/aplasia, and persistent hyperplastic primary vitreous. A functional assay demonstrated that each mutation decreased the transcriptional activation potential of PAX6 through the paired DNA-binding domain. PAX6 and PAX2 are each thought to downregulate the expression of the other. Four of the detected mutations affected PAX6-mediated transcriptional repression of the PAX2 promoter in a reporter assay. Because PAX2 gene mutations were detected in papillorenal syndrome, alternation of PAX2 function by PAX6 mutations may affect phenotypic manifestations of optic-nerve malformations.

Adult↗
PubMed2003

Caspase-8 and caspase-10 activate NF-kappaB through RIP, NIK and IKKalpha kinases.

NF-kappaB regulates the expression of various genes involved in cell growth and differentiation, immune response and inhibition of apoptosis. Recently, some death effector domain (DED)-containing proteins, such as FADD and c-FLIP were reported to activate NF-kappaB. We previously reported that the prodomain-only isoforms of caspase-8 and -10 (PDCasp8/10), containing two DED motifs, could inhibit Fas-mediated apoptosis. Here, we demonstrate that these isoforms also activate NF-kappaB, implying this to be one of the mechanisms by which these polypeptides inhibit apoptosis. The GST pull-down assay revealed that, among upstream kinases that activate NF-kappaB, only NIK and RIP, but not RICK or IKKalpha/beta, could directly bind to PDCasp8/10. In addition, both modules ofDED in PDCasp8/10 were required for these interactions as well as NF-kappaB activation. Experiments using a kinase-dead mutant of IKKalpha and an RIP mutant lacking a kinase domain, both of which function as dominant-negative mutants for their wild-type counterparts, blocked PDCasp8/10-mediated NF-kappaB activation. Using small interfering RNA technology, we further demonstrate that the down-regulation of IKKalpha but not IKKbeta significantly inhibits PDCasp8-mediated NF-kappaB activation. Taken together, these results suggest that caspase-8 and -10 have roles in a non- or anti-apoptotic signaling pathway leading to NF-kappaB activation through RIP, NIK and IKKalpha.

Caspase 10↗
PubMed2003

Mutations in the human homologue of Drosophila patched in Japanese nevoid basal cell carcinoma syndrome patients.

Mutations in the human homologue of Drosophila patched (PTCH) have been identified in patients with nevoid basal cell carcinoma syndrome (NBCCS; also called Gorlin syndrome) as well as sporadic basal cell carcinomas and medulloblastomas. However, using PCR-SSCP analysis, mutations in PTCH have been found in only a fraction (about one third to a half) of NBCCS patients. In this study, we determined the whole genomic organizations of the PTCHgene and developed a new set of more accurate primers for the analysis of mutations in PTCH. Using these primers, we examined 8 Japanese NBCCS patients for mutations in all PTCH exons by direct sequencing of the PCR products. As a result, we identified 5 novel PTCH mutations in 6 out of 8 patients including 2 sisters as well as 5 polymorphisms, two of them, 1704G>C and 2928G>C were novel. Four of these mutations, 900delC, 1247insT, 1999delC and 933+5G>T, cause protein truncation due to the insertion or deletion of a single nucleotide or aberrant splicing. The remaining mutation, 1514G>A was a missense alteration (G509D). Interestingly, the amino acid substitution, G509V, has been reported previously in an NBCCS patient, suggesting an important role of this amino acid residue in the function of PTCH protein. The difference in the detection rate of PTCH mutations among NBCCS between previous reports and ours is due to the difference either in ethnicity or in the detection methods.

Amino Acid Sequence↗
PubMed2003

Interaction of human herpesvirus 6 with human CD34 positive cells.

We reported previously that human herpesvirus 6 (HHV-6) suppresses hematopoietic colony formation of erythroid (BFU-E), granulocyte/macrophage (CFU-GM), and megakaryocyte (CFU-Meg) lineages in vitro. Here we describe the interaction between HHV-6 and human CD34+ cells, which are a major source of hematopoietic progenitor cells. CD34+ cells were immunomagnetically isolated from cord blood mononuclear cells using anti-CD34+ antibodies coated onto either Dynabeads trade mark or MACS beads. The CD34+ population selected with Dynabeads showed a broad range of fluorescence. The population selected with MACS beads showed a narrow range of fluorescence. After infection with HHV-6, two transcripts of the immediate early genes were detected with both cell populations. HHV-6 suppressed colony formation of BFU-E, CFU-GM, and CFU-Meg. HHV-6 suppressed cell growth after 3 to 7 days culture in the presence of thrombopoietin (TPO). More differentiated CD34+ cells were more susceptible to the effects of HHV-6. These data indicate that the targets for hematopoietic suppression by HHV-6 are the differentiated cells.

Antigens, CD34↗
PubMed2003

Improvement of skeletal lesions in mice with mucopolysaccharidosis type VII by neonatal adenoviral gene transfer.

Neonatal gene transfer using adenovirus vectors expressing human beta-glucuronidase (AxCAhGUS) resulted in pathological improvement in multiple visceral organs of mice with mucopolysaccharidosis type VII (MPSVII). However, the therapeutic effect on skeletal deformities and growth retardation, the major clinical symptoms in MPSVII, was not fully investigated by biochemical and histopathological analyses. In this study, we injected AxCAhGUS into a murine model of MPSVII (B6/MPSVII) within 24 h of birth and evaluated the therapeutic effects on skeletal deformities and growth retardation. High levels of beta-glucuronidase (GUSB) activity (approximately threefold higher than normal GUSB activity) were observed in the articular cartilage of the mice 30 days after the treatment. Histopathological study in the knee joints showed elimination of vacuole cells in the articular cartilage and growth plate. Subchondral bone near the articular surface was almost normal in the treated MPSVII mice. Long-term observation (for 140 days after treatment) indicated that characteristic phenotypes such as flattened face, hunched stature, and shortening of bone length in the treated mice were almost normal. These results demonstrate that a single injection of adenovirus vector into neonatal MPSVII mice is sufficient for long-term normalization of skeletal deformities and effective in pathological correction of the articular cartilage and growth plate.

Adenoviridae↗
PubMed2002

Analysis of gene expression patterns during glucocorticoid-induced apoptosis using oligonucleotide arrays.

To determine the genes responsible for mediating the effects of glucocorticoids (GCs) on leukemic cells, transcriptional changes in GC-sensitive human pre-B leukemia 697 cells during GC-induced apoptosis were monitored using oligonucleotide microarrays. To circumvent the challenge of recovering mRNAs from dying cells, we compared the pattern of gene expression with that of 697 cells protected from apoptosis by transfection with bcl-2. Of the 12,000 genes examined for their response to GC, 93 genes were induced and 28 genes were repressed, many of which are known to be implicated in signal transduction, growth arrest, and transcription. These included the signal transduction-related genes encoding SOCS1, SOCS2, FKBP51, DSCR1, p56lck, and four protein kinase phosphatases. Growth arrest-related genes encoding p19(INK4d) and several Myc inhibitors were induced in response to the GC treatment. Anti-proliferative- or apoptosis-related genes encoding BTG1, BTG2, and granzyme A were also found to be transcriptionally up-regulated by GC. In addition, the regulation of genes encoding the glucocorticoid receptor and steroid receptor coactivator-1 suggested autoregulation of a GC-mediated signaling pathway.

Antineoplastic Agents, Hormonal↗
PubMed2002

Death effector domain-only polypeptides of caspase-8 and -10 specifically inhibit death receptor-induced cell death.

Caspase-8 and -10 are thought to be involved in a signaling pathway leading to death receptor-mediated apoptosis. The prodomains of these caspases are known to form fibrous structures in the perinuclear region when overexpressed, though the meaning of the structures remains unclear. In a previous study we showed that the overexpressed caspase-8 or -10 prodomain (PDCasp8 or PDCasp10) did not induce cell death, and we hypothesized that these prodomains interfere with the receptor-mediated cell death signaling pathway. Indeed, in 293, HeLa and Jurkat cells, cell death mediated by agonistic anti-Fas antibody, TRAIL or overexpression of full-length caspase-8 was significantly inhibited by overexpression of PDCasp8 or PDCasp10 which colocalized with the Golgi complex and with overexpressed FADD. However, when about 20 amino acid residues were deleted from either terminus of the caspase-10 prodomain (amino acid residue 1 to 219), the ability to inhibit Fas-mediated cell death was lost. Interestingly, these deletion mutants also lost the ability to make fibrous structures and to bind FADD, suggesting that FADD binding is important for their function, and that PDCasp8 and PDCasp10 act as dominant-negative inhibitors.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Prolongation of transgene expression by coexpression of cytokine response modifier a in rodent liver after adenoviral gene transfer.

The short duration of expression of the transgenes is a major barrier to the clinical application of adenovirus-mediated gene therapy for hepatic enzyme deficiencies. Previous reports show that Fas-mediated apoptosis has a pivotal role in the rapid elimination of adenovirus-infected hepatocytes. After considering this result and our recent observation that murine hepatocytes can be protected from Fas-mediated apoptosis by expressing cytokine response modifier A (CrmA) in vivo, we hypothesized that CrmA coexpression could also prevent adenovirus-infected hepatocytes from rapid elimination and that this would make prolonged transgene expression achievable in vivo. To examine this, mice with congenital deficiency of lysosomal beta-glucuronidase (GUSB) were infected with recombinant adenoviruses expressing both CrmA and GUSB, and the duration of transgene expression was evaluated. The serum GUSB activity in the mice injected with a recombinant adenovirus expressing GUSB only became undetectable 60 days after the injection, whereas higher than normal GUSB activity was observed for at least 120 days in mice injected with adenoviruses expressing both GUSB and CrmA. Furthermore, we showed that exogenous CrmA expression could prevent the adenovirus-infected hepatocytes from cell death induced by cytotoxic T lymphocytes in vitro. These observations indicate that transgene expression after administration of E1-deleted adenovirus is prolonged by coexpression of the antiapoptotic protein CrmA.

Adenoviridae↗
PubMed2002

Neutralizing antibody responses to human herpesviruses 6 and 7 do not cross-react with each other, and maternal neutralizing antibodies contribute to sequential infection with these viruses in childhood.

Seroprevalence of human herpesvirus 6 (HHV-6) and HHV-7 infections is very high throughout the world, and almost all people are exposed first to HHV-6 and second to HHV-7 in their childhood. However, it is not clear whether the neutralizing (NT) antibody response between each virus is cross-reactive or not. To elucidate the NT antibody response between each virus, 55 serum samples from an adult group (subjects 22 to 88 years old) and 60 serum samples from a young group (subjects 2 to 18 years old) were examined by a dot blot method for detecting viral late antigen. Thirty-nine serum samples obtained from cord bloods and a few serum samples obtained from pediatric patients with exanthem subitum were also examined to assess the maternal transferred NT antibodies against each virus. The NT antibody titers against HHV-7 in the adult group remained high throughout all the individuals, and none were negative. Those against HHV-6 were high values in the young group but low values, including negative values (three samples), in the adult group. These results suggested that the NT antibody response to either HHV-6 or HHV-7 in each individual was specific to each virus and did not cross-react with each other. In the adult group, the NT antibody response to HHV-6 decreased, while that to HHV-7 remained high throughout all the individuals. Maternal transferred NT antibody titers against HHV-7 were higher and remained longer after birth than those of HHV-6, and these findings were in accord with the clinical observation that HHV-6 infection usually occurs earlier than HHV-7 infection.

Adolescent↗