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Biomedical subjects

Norio Suzuki

Publications and source records attributed to Norio Suzuki.

At least 73 records · Page 4Linked to original sources
PubMed2003

Intestinal aganglionosis associated with the Waardenburg syndrome: report of two cases and review of the literature.

The authors report two cases of the rare concurrence of intestinal aganglionosis and Waardenburg syndrome in Japanese infants. The patients were a 1-month-old girl and a 3-month-old boy at diagnosis, and both of them had either short segment or ultra-short segment aganglionosis. A review of 48 cases in the literature showed that the extent of the aganglionic segment is quite variable, from nearly total to ultra-short. The clinical features of aganglionosis in Waardenburg syndrome would appear to bear similarity in sex ratio and the extent of aganglionosis with those of Hirschsprung's disease associated with Ondine's curse, another type of neurocristopathy.

Comorbidity↗
PubMed2003

Four functionally distinct C-type natriuretic peptides found in fish reveal evolutionary history of the natriuretic peptide system.

Natriuretic peptides (NPs) are major cardiovascular and osmoregulatory hormones in vertebrates. Although tetrapods generally have three subtypes, atrial NP (ANP), B-type NP (BNP), and C-type NP (CNP), some teleosts lack BNP, and sharks and hagfish have only one NP. Thus, NPs have diverged during fish evolution, possibly reflecting changes in osmoregulatory systems. In this study, we found, by cDNA cloning, four distinct CNPs (1 through 4) in the medaka (Oryzias latipes) and puffer fish (Takifugu rubripes), although to our knowledge no more than two CNPs have been isolated from a vertebrate species. Predicted mature CNP-1 was most similar, and CNP-4 was most dissimilar, to mammalian CNPs. However, synthetic CNP-4 most potently activated OlGC1, a medaka CNP-specific receptor (NPR-B) expressed in cultured cells, whereas CNP-1 and CNP-3 most activated OlGC7 and OlGC2, two medaka homologues of the ANP/BNP receptor (NPR-A), respectively. Linkage mapping in medaka followed by comparative genomic analyses among fishes and humans located four CNP genes in separate medaka chromosomes corresponding to human chromosomes 1, 2, 12, and 17. From conserved synteny, the following evolutionary history of NPs was evoked: (i) four CNP genes were generated by chromosomal duplications before the divergence of elasmobranchs; (ii) the CNP-3 gene generated ANP and BNP genes through tandem duplication before the divergence of tetrapods and teleosts; (iii) CNP-1 and -2 genes were retained in the teleost lineage but not in the tetrapod lineage; (iv) the CNP-3 gene disappeared from the tetrapod lineage after divergence of amphibians; and (v) the CNP-4 gene is retained in humans as CNP.

Amino Acid Sequence↗
PubMed2003

Identification and characterization of 2 types of erythroid progenitors that express GATA-1 at distinct levels.

Transcription factor GATA-1 is essential for the development of the erythroid lineage. To ascertain whether strict control of GATA-1 expression level is necessary for achieving proper erythropoiesis, we established transgenic mouse lines expressing green fluorescent protein (GFP) under the control of the GATA-1 gene hematopoietic regulatory domain. We examined the GATA-1 expression level by exploiting the transgenic mice and found 2 GFP-positive hematopoietic progenitor fractions in the bone marrow. One is the GFPhigh fraction containing mainly CFU-E and proerythroblasts, which coexpress transferrin receptor, while the other is the GFPlow/transferrin receptor-negative fraction containing BFU-E. Since the intensity of green fluorescence correlates well with the expression level of GATA-1, these results indicate that GATA-1 is highly expressed in erythroid colony-forming unit (CFU-E) but low in erythroid burst-forming unit (BFU-E), suggesting that the incremental expression of GATA-1 is required for the formation of erythroid progenitors. We also examined GFP-positive fractions in the transgenic mouse spleen and fetal liver and identified fractions containing BFU-E and CFU-E, respectively. This study also presents an efficient method for enriching the CFU-E and BFU-E from mouse hematopoietic tissues.

Animals↗
PubMed2003

A GATA-specific inhibitor (K-7174) rescues anemia induced by IL-1beta, TNF-alpha, or L-NMMA.

Interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), or N(G)-monomethyl-L-arginine (L-NMMA) are increased in patients with chronic disease-related anemia. They increase the binding activity of GATA and inhibit erythropoietin (Epo) promoter activity. In this study, we examined the ability of K-7174 (a GATA-specific inhibitor) to improve Epo production when inhibited by treatment with IL-1beta, TNF-alpha, or L-NMMA. Epo protein production and promoter activity were induced in Hep3B cells with 1% O2. However, 15 U/ml IL-1beta, 220 U/ml TNF-alpha, or 10(-3) M L-NMMA inhibited Epo protein production and promoter activity, respectively. Addition of 10 microM K-7174 rescued these inhibitions of Epo protein production and promoter activity induced by IL-1beta, TNF-alpha, or L-NMMA, respectively. Electrophoretic mobility shift assays revealed that addition of K-7174 decreased GATA binding activity, which was increased with the addition of IL-1beta, TNF-alpha, or L-NMMA. Furthermore, intraperitoneal injection of mice with IL-1beta or TNF-alpha decreased the hemoglobin concentrations and reticulocyte counts. However, the addition of K-7174 reversed these effects. These results raise the possibility of using K-7174 as therapy to treat anemia.

Anemia↗
PubMed2003

Caspase-mediated cleavage of JNK during stress-induced apoptosis.

The c-Jun N-terminal kinases (JNKs) are a subfamily of the mitogen-activated protein kinases (MAPKs). The JNKs are encoded by three separate genes (jnk1, jnk2, and jnk3), which are spliced alternatively to create 10 JNK isoforms that are either p46 or p54 in size. In this study, we found that the p52 form of JNK emerged in human leukemia MOLT-4 or U937 cells following X-irradiation or heat treatment. The accumulation of p52 coincided with the reduction of p54 JNK. On the other hand, the amounts of p46 JNK did not change by X-irradiation. Induction of the p52 form of JNK also paralleled the appearance of the active form of caspase-3 and was suppressed by a caspase-specific inhibitor, Ac-DEVD-CHO, but not by Ac-YVAD-CHO. In vitro cleavage assays indicated that recombinant human JNK1beta2 and JNK2beta2 were cleaved by caspase-3, and that the mutation of aspartic acid at position 413 of JNK1beta2 or 410 of JNK2beta2 to alanine abolished the cleavage. Altogether, our results demonstrated that p54 JNKs, at least JNK1beta2 and JNK2beta2, were new selective targets of caspases in JNK splicing variants, and suggested that the p52 form could serve as a marker of apoptosis.

Alternative Splicing↗
PubMed2003

Encephalopathy in megacystis-microcolon-intestinal hypoperistalsis syndrome patients on long-term total parenteral nutrition possibly due to selenium deficiency.

This report concerns two patients (female, 9 and 6 years) who were diagnosed with megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). Although they exceeded the usual life expectancy of patients diagnosed with MMIHS because of total parenteral nutrition (TPN), they demonstrated progressive neurological deficits and showed histopathological features in the brain. Both patients were diagnosed with MMIHS in the neonatal period and were fed by TPN. The first patient developed visual and gait disturbances at the age of 7 years. Two months later, she developed dysarthria and muscular weakness, and could not maintain her posture. The level of serum selenium was extremely low. The second patient developed flexion and spasticity of the extremities followed by decorticate posture at the age of 3 years. Both patients died of sepsis. The brain weights of the two cases were 880 g and 715 g. In both cases, severe neuronal loss and gliosis were present in the medial convolutions of the occipital lobe, including the visual cortex. The postcentral gyrus and temporal transverse gyrus were also involved. In addition, extensive loss of Purkinje cells and granular neurons, and gliosis were observed in the cerebellum. We measured the selenium content of the brains and livers using the graphite furnace atomic absorption spectrometry method. Selenium was not detected in either brain, although the livers of both cases contained a low level of selenium. On immunohistochemical examination of the anti-oxidative enzymes, histiocyte-macrophage lineage cells in MMIHS cases, including microglia and Kupffer cells, showed only a weak reaction for glutathione peroxidase, of which selenium is an essential component. However, the cells in the control cases were strongly positive. In cases of MMIHS and methylmercury intoxication, the brain features similar lesions, in both their topographical and histopathological aspects. We considered that the brain lesions of the MMIHS patients mainly resulted from oxidative damage of the brain related to the low levels of glutathione peroxidase and other selenoproteins due to selenium deficiency.

Abnormalities, Multiple↗
PubMed2003

Expression and domain-specific function of GATA-2 during differentiation of the hematopoietic precursor cells in midgestation mouse embryos.

The aorta-gonads-mesonephros (AGM) region of the mouse embryo has been assigned as the origin of definitive hematopoiesis. The transcription factor GATA-2 has specific but unclarified roles in early hematopoiesis. To elucidate the expression profile of GATA-2, we prepared transgenic mouse lines containing the green fluorescent protein (GFP) gene driven by GATA-2 gene regulatory elements. We also prepared a mouse line in which GFP reporter sequences were inserted into the endogenous GATA-2 gene. Both mouse mutants expressed GFP in the early hematopoietic tissues. The CD45 antigen, a marker of hematopoietic cells, was expressed in a small fraction of transgene (TG)-derived GFP+ cells. The remaining TG-GFP+/CD45- cells were adherent to plastic and produced CD45+ hematopoietic cells abundantly when cultured in vitro. Exogenous expression of GATA-2 in TG-GFP+/CD45- cells from the AGM region inhibited their differentiation into CD45+ cells. Loss of GATA-2 function through the disruption of the GATA-2 locus enhanced the earlier emergence of CD45+ cells in the yolk sac of the 9.5-day conceptus. These results demonstrated that GATA-2 is expressed in the precursor of hematopoietic cells and works as a gatekeeper to preserve their immaturity. A reduction of GATA-2 expression or activity is required for the differentiation of precursors to hematopoietic cells.

Animals↗
PubMed2003

Suppression of erythropoietin gene expression by cadmium depends on inhibition of HIF-1, not stimulation of GATA-2.

Long-term exposure of rats to cadmium (Cd) resulted in a marked suppression of erythropoietin (Epo) mRNA expression in the kidneys and the development of severe anemia. A recent report revealed that Cd inhibited hypoxia-inducible factor 1 (HIF-1) binding activity and Epo mRNA expression and protein production. However, Epo gene expression is also regulated by transcription factor GATA-2, which binds to the GATA binding site of the Epo promoter. To elucidate the mechanism of suppression of Epo by Cd, the effect of Cd on GATA-2 function was studied. Epo promoter/enhancer luciferase constructs, one with the wild-type promoter and another with a promoter with a mutant GATA site, were transfected into Hep3B cells. No significant difference in Epo promoter activity in these two types of cells was observed in the presence of Cd. The binding activity of GATA-2 was not affected by Cd. This study showed that Cd inhibited HIF-1 binding activity and Epo promoter activity, and then suppressed Epo protein production. Inhibition of Epo gene expression by Cd depends on suppression of HIF-1 binding activity, not on alteration of GATA function.

Cadmium↗
PubMed2003

HLF/HIF-2alpha is a key factor in retinopathy of prematurity in association with erythropoietin.

An HLF (HIF-1alpha-like factor)/HIF-2alpha-knockout mouse is embryonic lethal, preventing investigation of HLF function in adult mice. To investigate the role of HLF in adult pathological angiogenesis, we generated HLF-knockdown (HLF(kd/kd)) mice by inserting a neomycin gene sandwiched between two loxP sequences into exon 1 of the HLF gene. HLF(kd/kd) mice expressing 80-20% reduction, depending on the tissue, in wild-type HLF mRNA were fertile and apparently normal. Hyperoxia-normoxia treatment, used as a murine model of retinopathy of prematurity (ROP), induced neovascularization in wild-type mice, but not in HLF(kd/kd) mice, whereas prolonged normoxia following hyperoxic treatment caused degeneration of retinal neural layers in HLF(kd/kd) mice due to poor vascularization. Cre-mediated removal of the inserted gene recovered normal HLF expression and retinal neovascularization in HLF(kd/kd) mice. Expression levels of various angiogenic factors revealed that only erythropoietin (Epo) gene expression was significantly affected, in parallel with HLF expression. Together with the results from intraperitoneal injection of Epo into HLF(kd/kd) mouse, this suggests that Epo is one of the target genes of HLF responsible for experimental ROP.

Animals↗
PubMed2003

Promoter analysis of a medaka fish intestinal guanylyl cyclase gene.

We characterized the promoter activity of a medaka fish intestinal guanylyl cyclase gene, OlGC6, by assay of enzyme activity in response to various promoter-luciferase fusion gene constructs introduced into CACO-2 cells and medaka fish embryos. A transient transfection assay of the various fusion gene constructs showed that the nucleotides between -98 and -89 in the 5'-flanking region of the OlGC6 gene are essential for transcription of the OlGC6 gene in CACO-2, and that the OlGC6 gene fragment between -98 and +50 is sufficient to drive gene expression in the medaka fish intestine. An electrophoretic mobility shift assay and ultraviolet (UV) cross-linking experiments demonstrated that a nuclear protein from CACO-2 cells and the adult medaka fish intestinal cells binds specifically to the AGACCTTTGC nucleotides in the regulatory element.

5' Flanking Region↗
PubMed2003

Continuous versus intermittent administration of human endostatin in xenografted human neuroblastoma.

PURPOSE: The authors examined whether recombinant human endostatin (rhEndostatin), an antiangiogenic agent, is effective against a human neuroblastoma cell line (designated TNB9) using a human neuroblastoma xenograft model and investigated whether continuous infusion is more effective than intermittent administration. METHODS: In the first experiment, when tumors on the back of nude mice reached a weight of 90 to 95 mg, rhEndostatin, 10 mg/kg/d mouse weight, was administered subcutaneously to the mice (n = 5) every day for 10 consecutive days. In the second experiment, the same daily dose of rhEndostatin was administered continuously to the TNB9-bearing mice (n = 6) via subcutaneous infusion pumps for 3 consecutive days with total dose being 30% of that in the first experiment. Nestin and factor VIII expression levels were studied immunohistochemically to elucidate whether histologic evidence of the effects of rhEndostatin was present on day 4 in the second experiment. RESULTS: In the first experiment, relative tumor weight in treated mice (n = 5) was significantly less than that in controls (n = 12) on day 2 only after treatment initiation (P <.05). The maximum inhibition rate (MIR) of TNB9 xenograft growth by rhEndostatin was 46.4%, indicating lack of efficacy. In the second experiment, the effects of rhEndostatin were much more marked than those in the first experiment, with an MIR of 60.7%. The mean relative tumor weight in the treated group (n = 6) in the second experiment was significantly less than that in controls (n = 10) on days 2, 4, and 6 (P <.01) as well as on days 8 and 10 (P <.05). Nestin staining in the endothelium of control tumors (n = 2) was marked, whereas it showed a loss of fibrillar structure in rhEndostatin-treated tumors (n = 2). The number of vessels immunostained with antifactor VIII antibody was markedly reduced in tumors (n = 2) from rhEndostatin-treated mice compared with that in tumors from control animals (n = 2). CONCLUSIONS: Continuous administration of rhEndostatin resulted in more significant tumor regression than intermittent administration of the agent in the same model. This indicates that rhEndostatin, if administered in continuous fashion, could become an effective agent for treating patients with neuroblastoma in the future.

Abdominal Neoplasms↗
PubMed2003

Intrahepatic biliary cysts in biliary atresia in the era of liver transplantation.

OBJECTIVES: The development of intrahepatic biliary cysts (IBC) after Kasai operation in patients with biliary atresia (BA) is recognized as an important problem; however, management strategy for IBC has not been clarified, particularly in the light of the increased use of liver transplantation. METHODS: Forty consecutive BA patients underwent hepatic portoenterostomy during 18 years from 1983 to 2000. We compared the clinical course and prognosis of the patients who developed IBC with those who did not. RESULTS: Seven of the 40 patients developed IBC. Three patients had type A (non-communicating cyst) and three patients had type C (multiple cystic dilation) IBC, and the remaining patients had type B (communicating cyst). Of the 7 patients, one patient underwent successful internal intestinal drainage, and one patient died of complications at the time of internal intestinal drainage. Three patients underwent liver transplantation due to either hepato-pulmonary syndrome (one case) or liver failure (two cases). One patient with IBC with liver failure was judged to require transplant, but was found to have pulmonary hypertension and was thus not a candidate. The remaining patient has survived without jaundice for 21 months postoperatively. Two of 21 patients with good initial bile drainage and without IBC underwent liver transplantation. The percentage of patients undergoing transplant was significantly higher in the group with IBC than in the group without IBC (P < 0.05). CONCLUSIONS: IBC was associated with worsening liver function. Previously, IBC was treated using internal/external drainage, or the patients were observed without treatment, with limited success. We now consider it reasonable to carry out liver transplantation in patients with long-standing IBC.

Adolescent↗
PubMed2003

Factor structure of a modified version of the wisconsin card sorting test: an analysis of executive deficit in Alzheimer's disease and mild cognitive impairment.

In order to explore the factor structure of a modified version of the Wisconsin Card Sorting Test (mWCST) and to identify the dimensions of deficit in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI), conventional mWCST scores in 55 AD patients, 17 MCI patients, and 22 controls were subjected to factor analysis. Three factors, perseveration, inefficient sorting, and nonperseverative error, were obtained. Perseveration score was significantly poorer in both AD and MCI than in controls. By contrast, the MCI group showed significantly poorer scores on the nonperseverative error factor than did the AD patients, and the controls yielded intermediate values between the two patient groups. The perseveration factor was significantly correlated with the other estimates of executive function. This study suggested that the many mWCST scores could be reduced to three major factors, and that the perseveration score may effectively represent an aspect of executive dysfunction in AD and MCI patients.

Aged↗
PubMed2003

SDF-9, a protein tyrosine phosphatase-like molecule, regulates the L3/dauer developmental decision through hormonal signaling in C. elegans.

The dauer larva of the nematode Caenorhabditis elegans is a good model system for investigating the regulation of developmental fates by environmental cues. Here we show that SDF-9, a protein tyrosine phosphatase-like molecule, is involved in the regulation of dauer larva formation. The dauer larva of sdf-9 mutants is different from a normal dauer larva but resembles the dauer-like larva of daf-9 and daf-12 dauer-constitutive mutants. Like these mutants, the dauer-constitutive phenotypes of sdf-9 mutants were greatly enhanced by cholesterol deprivation. Epistasis analyses, together with the relationship between sdf-9 mutations and daf-9 expression, suggested that SDF-9 increases the activity of DAF-9 or helps the execution of the DAF-9 function. SDF-9 was expressed in two head cells in which DAF-9 is expressed. By their position and by genetic mosaic experiments, we identified these cells as XXXL/R cells, which are known as embryonic hypodermal cells and whose function at later stages is unknown. Killing of the sdf-9-expressing cells in the wild-type first-stage larva induced formation of the dauer-like larva. Since this study on SDF-9 and former studies on DAF-9 showed that the functions of these proteins are related to those of steroids, XXXL/R cells seem to play a key role in the metabolism or function of a steroid hormone(s) that acts in dauer regulation.

Alleles↗
PubMed2003

Wortmannin-enhanced X-ray-induced apoptosis of human T-cell leukemia MOLT-4 cells possibly through the JNK/SAPK pathway.

We demonstrated that enhancement of X-ray-induced apoptosis/rapid cell death by wortmannin accompanied by increased activation of JNK/SAPK in human leukemia MOLT-4 cells. Rapid cell death/apoptosis was determined either by the dye exclusion test or by the appearance of Annexin V-positive cells and cleaved PARP fragments. Enhancement was observed only at higher concentrations of wortmannin, i.e. 1 microM or more. At these high concentrations, both DNA-PK and ATM were inhibited. X-ray-induced phosphorylation of Ser 15 of p53/TP53, accumulation of both p53/TP53 and p21/WAF1/CDKN1A, and phosphorylation of XRCC4 were all suppressed. The enhancement of apoptosis/rapid cell death by wortmannin was prevented by addition of caspase inhibitors, Z-VAD-FMK or Ac-DEVD-CHO, or by transfection and overexpression of mouse Bcl2, which is known as an anti-apoptosis protein. The requirement for a high concentration of wortmannin, i.e. 1 microM or more, indicates that inhibition of both DNA-PK and ATM was necessary for the enhanced apoptosis/rapid cell death. Phosphorylation of AKT/PKB was completely suppressed at a much lower concentration, i.e. 0.1 microM wortmannin, where no enhancement of X-ray-induced apoptosis/rapid cell death was observed. On the other hand, X-ray-induced phosphorylation of JNK and its kinase activity as well as apoptosis/rapid cell death were all significantly enhanced only at high concentrations of wortmannin, i.e. 1 microM or more. Furthermore, the extent of enhancement of both JNK phosphorylation and of apoptosis/rapid cell death by wortmannin was less in Rh1a cells, which are ceramide- and radiation-resistant variant cells compared to the parental MOLT-4 cells. Therefore, activation of the JNK pathway was considered important for the enhancement of X-ray-induced apoptosis/rapid cell death of MOLT-4 cells by wortmannin, because of the requirement for a higher concentration of wortmannin than that required for inhibition of AKT phosphorylation. The suppression of the AKT-dependent pathway by wortmannin may have some underlying role in activating the JNK pathway toward the enhancement of cell death in the current system.

Androstadienes↗
PubMed2003

Genomic structure and expression of the soluble guanylyl cyclase alpha2 subunit gene in the medaka fish Oryzias latipes.

A cDNA clone encoding the soluble guanylyl cyclase alpha2 subunit was isolated from medaka fish (Oryzias latipes) and designated as OlGCS-alpha2. The OlGCS-alpha2 cDNA was 3,192 bp in length and the open reading frame (ORF) encodes a protein of 805 amino acids. The deduced amino acid sequence has high similarity to that of the mammalian alpha2 subunit gene except for the N-terminal regulatory domain. The C-terminal 5 amino acids, "RETSL", which have been reported to interact with the post synaptic density protein (PSD)-95 were conserved. An RNase protection assay with adult fish organs showed that OlGCS-alpha2 was expressed mainly in the brain and testis. The complete nucleotide sequence (about 41 kbp) of the OlGCS-alpha2 genomic DNA clone isolated from a medaka fish BAC library indicated that the OlGCS-alpha2 gene consisted of 9 exons and 8 introns. The 5'-flanking region and larger introns, such as introns 1, 4, and 7, contained the several fragments conserved in the nucleotide sequences of Rex6 (non-long terminal repeat retrotransposon), MHC class I genomic region, and OlGC1, the medaka fish homolog of the mammalian guanylyl cyclase B gene. Linkage analysis on the medaka fish chromosome demonstrated that the OlGCS-alpha2 gene was mapped to LG13; this mapping position was different from those for the OlGCS-alpha1 and OlGCS-beta1 genes (LG1).

Amino Acid Sequence↗
PubMed2003

Expression of membrane-bound and soluble guanylyl cyclase mRNAs in embryonic and adult retina of the medaka fish Oryzias latipes.

Localization of mRNAs for four membrane-bound guanylyl cyclases (membrane GCs; OlGC3, OlGC4, OlGC5, and OlGC-R2), three soluble guanylyl cyclase subunits (soluble GC; OlGCS-alpha(1), OlGCS-alpha(2), and OlGCS-beta(1)), neuronal nitric oxide synthase (nNOS), and cGMP-dependent protein kinase I (cGK I) was examined in the embryonic and adult retinas of the medaka fish Oryzias latipes by in situ hybridization. All of the membrane GC mRNAs were detected in the photoreceptor cells of the adult and embryonic retinas, but in different parts; the OlGC3 and OlGC5 mRNAs were expressed in the proximal part and the OlGC4 and OlGC-R2 mRNAs were expressed in the outer nuclear layer. The mRNA for nNOS was expressed in a scattered fashion on the inner side of the inner nuclear layer in the adult and embryonic retinas. The mRNAs (OlGCS-alpha(2) and OlGCS- beta(1)) of two soluble GC subunits (alpha(2) and beta(1)) were expressed mainly in the inner nuclear layer and the ganglion cell layer of the embryonic retina while the mRNAs of the soluble GC alpha(1) subunit and cGK I were not detected in either the adult or embryonic retina. These results suggest that NO itself and/or the cGMP generated by soluble GC (alpha(2)/beta(1) heterodimer) play a novel role in the neuronal signaling and neuronal development in the medaka fish embryonic retina in addition to the role played by phototransduction through membrane GCs in the adult and embryonic retinas.

Aging↗