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Biomedical subjects

N Suzuki

Publications and source records attributed to N Suzuki.

At least 217 records · Page 12Linked to original sources
PubMed2000

Thymidine diphosphate-6-deoxy-L-lyxo-4-hexulose reductase synthesizing dTDP-6-deoxy-L-talose from Actinobacillus actinomycetemcomitans.

The serotype c-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans NCTC 9710 contains an unusual sugar, 6-deoxy-L-talose, which has been identified as a constituent of cell wall components in some bacteria. Two genes coding for thymidine diphosphate (dTDP)-6-deoxy-L-lyxo-4-hexulose reductases were identified in the gene cluster required for biosynthesis of serotype c-specific polysaccharide. Both dTDP-6-deoxy-L-lyxo-4-hexulose reductases were overproduced and purified from Escherichia coli transformed with the plasmids containing these genes. The sugar nucleotides converted by both reductases were purified by reversed-phase high performance liquid chromatography and identified by (1)H nuclear magnetic resonance and gas-liquid chromatography. The results indicated that one of two reductases produced dTDP-6-deoxy-L-talose and the other produced dTDP-L-rhamnose (dTDP-6-deoxy-L-mannose). The amino acid sequence of the dTDP-6-deoxy-L-lyxo-4-hexulose reductase forming dTDP-6-deoxy-L-talose shared only weak homology with that forming dTDP-L-rhamnose, despite the fact that these two enzymes catalyze the reduction of the same substrate and the products are determined by the stereospecificity of the reductase activity. Neither the gene for dTDP-6-deoxy-L-talose biosynthesis nor its corresponding protein product has been found in other bacteria; this biosynthetic pathway is identified here for the first time.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Structures, enzymatic properties, and expression of novel human and mouse secretory phospholipase A(2)s.

Mammalian secretory phospholipase A(2)s (sPLA(2)s) form a family of structurally related enzymes that are involved in a variety of physiological and pathological processes via the release of arachidonic acid from membrane phospholipids or the binding to specific membrane receptors. Here, we report the cloning and characterization of a novel sPLA(2) that is the sixth isoform of the sPLA(2) family found in humans. The novel human mature sPLA(2) consists of 123 amino acids (M(r) = 14,000) and is most similar to group IIA sPLA(2) (sPLA(2)-IIA) with respect to the number and positions of cysteine residues as well as overall identity (51%). Therefore, this novel sPLA(2) should be categorized into group II and called group IIE (sPLA(2)-IIE) following the recently identified group IID sPLA(2) (sPLA(2)-IID). The enzymatic properties of recombinant human sPLA(2)-IIE were almost identical to those of sPLA(2)-IIA and IID in terms of Ca(2+) requirement, optimal pH, substrate specificity, as well as high susceptibility to the sPLA(2) inhibitor indoxam. Along with the biochemical properties of proteins, genetic and evolutional similarities were also observed among these three types of group II sPLA(2)s as to the chromosomal location of the human gene (1p36) and the exon/intron organization. The expression of sPLA(2)-IIE transcripts in humans was restricted to the brain, heart, lung, and placenta in contrast to broad expression profiles for sPLA(2)-IIA and -IID. In sPLA(2)-IIA-deficient mice, the expression of sPLA(2)-IIE was markedly enhanced in the lung and small intestine upon endotoxin challenge, which contrasted with the reduced expression of sPLA(2)-IID mRNA. In situ hybridization analysis revealed elevation of sPLA(2)-IIE mRNA at alveolar macrophage-like cells in the lung of endotoxin-treated mice. These findings suggest a distinct functional role of novel sPLA(2)-IIE in the progression of inflammatory processes.

Amino Acid Sequence↗
PubMed2000

Cloning of a calcitonin gene-related peptide receptor and a novel calcitonin receptor-like receptor from the gill of flounder, Paralichthys olivaceus.

For the first time in non-mammalian vertebrates, cDNA encoding CGRPR was isolated from the gill cDNA library of flounder. The nucleotide sequence consists of a 237bp 5'-UTR, a 1398bp coding sequence for a 465-amino-acid protein, and a 981bp 3'-UTR. The predicted amino-acid sequence has a high degree of identity to hCGRPR (72.3%) and rCGRPR (71.6%) and, to a lesser degree, to hCTR (55.6%) and rCTR (59.3%). In addition, a different type of receptor cDNA was also obtained from the gill cDNA. The nucleotide sequence contains an open-reading frame of 1380bp to produce a 459-amino-acid protein. The open-reading frame of this receptor shows the same degree of identity to mammalian CTR (60.2% to hCTR; 62.3% to rCTR) and CGRPR (64.6% to hCGRPR; 64.4% to rCGRPR). However, the predicted amino-acid sequence was more homologous to hCGRPR (60.2%) and rCGRPR (61.3%) than to hCTR (48.8%) and rCTR (49.5%). The identity of this receptor to fCGRPR is 66.6% at the nucleotide level and 64.2% at the amino-acid level, indicating that the receptor is not likely to be an isoform of CGRPR. The receptor, but not fCGRPR, is expressed in bones, suggesting the possibility that this receptor corresponds to the flounder CTR.

Amino Acid Sequence↗
PubMed2000

Prevention of v-Ha-Ras-dependent apoptosis by PDGF coordinates in phosphorylation of ERK and Akt.

In some v-Ha-ras-transfected cell lines, serum deprivation results in apoptosis. Clarification of the molecular mechanisms by which oncogenic Ras controls susceptibility to apoptosis may assist in the development of effective therapies against human cancer with oncogenic ras gene. In this report, we established a v-Ha-ras-transfected human fibroblast clone, R1. In R1 cells, induction of v-Ha-Ras enhanced susceptibility to cell death under serum-deprived conditions. Ladders of cellular DNA were identified only when oncogenic ras was induced under serum-deprived conditions. Platelet-derived growth factor (PDGF) precluded DNA fragmentation of serum-deprived v-Ha-ras-transformed cells. Under serum-depleted conditions, the amounts of activated ERK and Akt decreased as compared with those under serum-containing conditions. The decreased levels of activated ERK and Akt were restored by the addition of PDGF. Inhibition of phosphorylated-ERK and Akt resulted in renewed susceptibility to cell death. These results indicate that failure of signal transduction of oncogenic Ras by the deficiency of growth factors such as PDGF causes v-Ha-Ras-dependent apoptosis.

Androstadienes↗
PubMed2000

5q- syndrome presenting chronic myeloproliferative disorders-like manifestation: a case report.

A 28-year-old Japanese woman with suspected essential thrombocythemia (ET) had marked thrombocytosis, mild leukocytosis with normal neutrophil alkaline phosphatase activity, and no anemia. She was monitored without being given any medication. Eleven years later, complete blood counts showed no remarkable changes but some non-lobulated mononuclear megakaryocytes were found in the bone marrow. Cytogenetic analysis revealed deletion of the long arm of chromosome 5 (5q-). Subsequently, hemoglobin and platelet counts decreased gradually, splenomegaly appeared and progressed, after which myelofibrosis developed. Acute leukemia developed 16 years after the first documentation of thrombocytosis. 5q- syndrome is known to be a myelodysplastic syndrome (MDS) with unique clinical features and cases with this syndrome presenting with thrombocytosis of more than 1,000 x 10(9)/L but without anemia are rare. Furthermore, it is noteworthy that in this patient transition to acute leukemia occurred following development of myelofibrosis and marked splenomegaly, which are generally observed in blastic crises resulting from chronic myeloproliferative disorders (CMPD). The patient showed features indicative of CMPD rather than of MDS in spite of presenting with 5q- chromosomal abnormality. This case supports the concept of "mixed myelodysplastic and myeloproliferative syndromes" and suggests the possibility of the appearance of CMPD-like manifestations in 5q- syndrome.

Adult↗
PubMed2000

Intracellular osteopontin is an integral component of the CD44-ERM complex involved in cell migration.

Osteopontin (OPN) is a secreted glycoprotein with mineral- and cell-binding properties that can regulate cell activities through integrin receptors. Previously, we identified an intracellular form of osteopontin with a perimembranous distribution in migrating fetal fibroblasts (Zohar et al., J Cell Physiol 170:88-98, 1997). Since OPN and CD44 expression are increased in migrating cells, we analyzed the relationship of these proteins with immunofluorescence and confocal microscopy. A distinct co-localization of perimembranous OPN and cell-surface CD44 was observed in fetal fibroblasts, periodontal ligament cells, activated macrophages, and metastatic breast cancer cells. The co-localization of OPN and CD44 was prominent at the leading edge of migrating fibroblasts, where OPN also co-localized with the ezrin/radixin/moesin (ERM) protein ezrin, as well as in cell processes and at attachment sites of hyaluronan-coated beads. The subcortical location of OPN in these cells was verified by cell-surface biotinylation experiments in which biotinylated CD44 and non-biotinylated OPN were isolated from complexes formed with hyaluronan-coated beads and identified with immunoblotting. That perimembranous OPN represents secreted protein internalized by endocytosis or phagocytosis appeared to be unlikely since exogenous OPN that was added to cell cultures could not be detected inside the cells. A physical association with OPN, CD44, and ERM, but not with vinculin or alpha-actin, was indicated by immunoadsorption and immunoblotting of cell proteins in complexes extracted from hyaluronan-coated beads. The functional significance of OPN in this complex was demonstrated using OPN-/- and CD-/- mouse fibroblasts which displayed impaired migration and a reduced attachment to hyaluronan-coated beads. These studies indicate that OPN exists as an integral component of a hyaluronan-CD44-ERM attachment complex that is involved in the migration of embryonic fibroblasts, activated macrophages, and metastatic cells.

Animals↗
PubMed2000

Molecular cloning of proopiomelanocortin cDNA from an elasmobranch, the stingray, Dasyatis akajei.

Recently, we have characterized a new MSH (named delta-MSH) which joins the group of MSHs (alpha, beta, gamma) in dogfish proopiomelanocortin (POMC). The present study has confirmed the presence of delta-MSH in POMC of another member of the elasmobranchian order, the stingray, Dasyatis akajei, by cDNA cloning from pituitary mRNAs. Overlapping partial cDNA clones corresponding to stingray POMC were amplified by PCR from single-strand cDNA prepared from pituitary poly (A)(+) RNA. Excluding the poly A tail, stingray POMC cDNA consists of 1077 base pairs (bp). It contains a 912-bp open reading frame encoding a signal peptide of 24 amino acids (aa) and a POMC of 280 aa. gamma-MSH, alpha-MSH, ACTH, delta-MSH, beta-MSH, and beta-endorphin are located at POMC (50-61), (115-127), (115-153), (182-193), (226-242), and (245-280), respectively. The stingray POMC is smaller than that of the dogfish POMC (294 aa) mainly due to the absence of a sequence of 11 consecutive aa between delta-MSH and beta-MSH. delta-MSH has been found only in the elasmobranchs and, therefore, delta-MSH might have evolved after the divergence of chondrichthians from the ancestral vertebrate lineage and before divergence of sharks and rays.

Amino Acid Sequence↗
PubMed2000

Metastatic colon carcinoma found within an inguinal hernia sac: report of a case.

We report herein the case of a patient in whom metastatic colon carcinoma was found within an inguinal hernia sac. According to Lejar's classification, colon carcinomas within inguinal hernias are categorized as intrasaccular- and saccular-type tumors. In our patient, asymptomatic transverse colon carcinoma was the primary lesion, and to the best of our knowledge, this is only the fourth case of such a saccular-type tumor to be reported in the literature. To date, 21 cases of intrasaccular tumors have been reported, and saccular-type tumors are considered to be an even rarer entity, unless the patients have obvious ascites, indicating peritonitis carcinomatosa. Histologic examination of the hernia sac is recommended for male patients of advanced age with an inguinal hernia, especially those who have previously undergone surgery for colorectal carcinoma.

Adenocarcinoma↗
PubMed2000

A case of Currarino triad with familial sacral bony deformities.

We describe a male patient presenting with Currarino triad: a recto-urethral fistula, sacral bony deformity, and a presacral teratoma. Clinical screening of his family revealed three additional cases with incomplete forms of this association. Cytogenetic findings in the patient and his mother were normal. This case suggests that the occurrence of an anorectal malformation together with a sacral bony deformity should raise a physician's index of suspicion for associated presacral tumors, and that screening of the patient's family members with sacral radiographs is necessary.

Anal Canal↗
PubMed2000

Ca2+ dynamics at the frog motor nerve terminal.

Rises in free [Ca2+]i in response to various tetanic stimuli (Ca2+ transient) in frog motor nerve terminals were measured by recording fluorescence changes of Ca2+ indicators and analyzed in relation to short-term synaptic plasticity. Ca2+ transients reached a plateau after 10-20 impulses at 100 Hz and decayed in a three-exponential manner, in which the fast component was predominant. The plateau and fast component of the Ca2+ transient were elevated infralinearly with an increase in tetanus frequency. Computer simulation showed that the Ca2+ transients estimated from fluorescence changes faithfully reflect the true changes in [Ca2+]i except for the initial 20 ms. A slow Ca2+ chelator, EGTA, loaded into the nerve terminal, decreased the magnitude of both the fast and slow components of facilitation of transmitter release and the time constant of the former. A fast Ca2+ chelator, BAPTA, decreased the magnitude of fast facilitation but slightly increased its time constant. These results suggest that Ca2+ transients in the frog motor nerve terminals are primarily caused by Ca2+ entry and are dissipated by three components, in which the rate of the fast component is equivalent to that of free Ca2+ diffusion. The residual Ca2+ in the nerve terminals after stimulation accounts for the fast component of facilitation.

Animals↗
PubMed2000

Growth-inhibitory effects of interferon-gamma on Neospora caninum in murine macrophages by a nitric oxide mechanism.

To clarify the effector pathway of Neospora caninum growth-inhibitory activity induced by interferon-gamma (IFN-gamma) in murine macrophages we examined the relationship between IFN-gamma and nitric oxide (NO). Production of NO was enhanced in cultures of macrophages supplemented with IFN-gamma, and dose-dependent growth inhibition was observed. These findings suggest that the inhibitory activity induced in macrophages by IFN-gamma is mediated NO molecules. A competitive inhibitor of the L-arginine-dependent effector pathway, NG-monomethyl-L-arginine, virtually abolished the inhibitory effects induced by IFN-gamma. From this finding it appears that the inhibitory effects induced by IFN-gamma in macrophages may be mediated by an L-arginine-dependent effector pathway that involves NO production. In vivo, mice with a targeted disruption of the inducible NO synthase gene (iNOS-/-) were more susceptible than wild-type mice to N. caninum. Therefore, the production of NO in macrophages induced by IFN-gamma is an important mechanism for the killing of intracellular N. caninum.

Animals↗
PubMed2000

Expression of SAG-1 of Toxoplasma gondii in transgenic mice.

We describe the expression of SAG-1 cDNA in B6C3F1 mice by microinjecting a 3.3 kbp DNA fragment, consisting of the cytomegalovirus enhancer-chicken beta-actin hybrid promoter and SAG-1 into the pronucleus of a fertilized egg at the one-cell stage. Offspring derived from this microinjection were analyzed for the integration and functional expression of the SAG-1 transgene. Steady-state expressions of both the mRNA for SAG-1 and SAG-1 protein product were detected in the brain, thymus, spleen and liver. Approximately 50% of F1 and F2 progeny inherited the SAG-1 transgene from SAG-1 transgenic mice in Mendelian fashion. These results indicated that SAG-1 transgenic lines were established. Transgenic mice harboring the SAG-1 gene will contribute a critical tool of defining the molecular mechanisms of SAG-1 in pathogenesis and host immune response.

3T3 Cells↗
PubMed2000

Olfactory epithelium consisting of supporting cells and horizontal basal cells in the posterior nasal cavity of mice.

The olfactory epithelium of mice generally consists of olfactory cells, progenitors of olfactory cells (globose basal cells), supporting cells, and horizontal basal cells. However, in the dorsal fossa (the roof) of the posterior nasal cavity of mice, we found seven epithelial patches consisting of only non-neuronal cell types, i.e., supporting cells and horizontal basal cells, among the normal olfactory epithelium. The supporting cells occupied three or four layers in the apical to middle regions; in the basal region, horizontal basal cells were localized in a single row adjacent to the basement membrane. Bowman's gland ducts were also present in the epithelium. Neuronal cells (olfactory cells and globose basal cells) were totally absent. The ultrastructure of the supporting cells, horizontal basal cells, and Bowman's glands was essentially similar to that in the normal olfactory epithelium. In the early postnatal period (P1-P7), cell types in the epithelium were the same as those in the normal olfactory epithelium. From P10 to P21, olfactory cells and globose basal cells had disappeared from the olfactory epithelium. At this period, the number of TUNEL-positive cells was significantly higher than that in the surrounding olfactory epithelium; ultrastructurally, many apoptotic figures were observed. This suggests that the epithelium consisting of supporting cells and horizontal basal cells is generated by the apoptotic death of olfactory cells and globose basal cells during postnatal development.

Age Factors↗
PubMed2000

Polychlorinated dibenzo-p-dioxins and dibenzofurans in sediment, soil, fish, shellfish and crab samples from Tokyo Bay area, Japan.

Concentrations of tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans in samples collected in or near Tokyo Bay, Japan, with a densely inhabited catchment area, were congener-specifically determined and discussed. Analyzed in this study were samples of surface sediment covering the whole bay area, reference soil representing atmospheric impact, and fish, shellfish and crab commonly consumed as food. The range of concentrations were comparable to or higher than those in other parts of Japan. The origins of these compounds in the catchment area of the bay were investigated in terms of homolog and isomeric compositions in the sediment samples. Biota-sediment accumulation factors for benthic species declined as the degree of chlorination increased.

Animals↗
PubMed2000

Determination of urinary 8-epi-prostaglandin F(2alpha) using liquid chromatography-tandem mass spectrometry: increased excretion in diabetics.

Liquid chromatography-tandem mass spectrometry (LC/MS-MS) was applied to the quantitative analysis of urinary 8-epi-prostaglandin F(2alpha) (8-epi-PGF(2alpha)) level. 8-Epi-PGF(2alpha) and its internal standard, [(2)H(4)]-8-epi-PGF(2alpha), were extracted from urine by using a solid phase extraction cartridge and loaded to LC/MS-MS in selected reaction monitoring (SRM) mode. The standard curve showed good linearity in the range of 40 pg to 10 ng (r = 0. 997). The accuracy of the added 8-epi-PGF(2alpha) ranged from 96.8 to 104.9% with a mean +/- SD of 99.5+/-2.5%. The average level +/- SD of urinary 8-epi-PGF(2alpha) in 13 healthy volunteers (five women and eight men, 31+/-7.4 years old) was 429.4+/-149.6 pg/mg creatinine. The level of seven patients with noninsulin dependent diabetes mellitus (two women and five men, 40+/-13.6 years old), 630.9+/-275.6 pg/mg creatinine, was statistically higher than that of healthy volunteers (P<0.05). This finding suggested that diabetics are in a highly oxidative condition. This simple and rapid LC/MS-MS method can be used to elucidate the pathophysiological feature of diabetes or for monitoring the curative effect.

Adult↗
PubMed2000

Difference in urinary LTE4 and 11-dehydro-TXB2 excretion in asthmatic patients.

Bronchoconstrictor cysteinyl leukotrienes (LT) and thromboxane (TX) A2 have been implicated in the pathogenesis of asthma. Determination of urinary leukotriene E4 (LTE4) and 11-dehydro-TXB2 levels are often used to assess cysteinyl LT and TXA2 production in humans. To define the potential role in the pathogenesis of asthma, we investigated the urinary LTE4 and 11-dehydro-TXB2 levels. LTE4 and 11-dehydro-TXB2 levels were determined using liquid chromatography/tandem mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS), respectively. Urinary LTE4 levels in asthmatic patients (192 +/- 122 pg/mg creatinine, n = 14) were significantly higher (P < 0.005) than those in healthy volunteers (55 +/- 16 pg/mg creatinine, n = 13), but no significant difference in 11-dehydro-TXB2 levels was observed. A significant inverse correlation (r = -0.821, P < 0.005) was found between urinary LTE4 levels and the forced expiratory volume in 1 s (FEV1) but no significant correlation was observed between urinary 11-dehydro-TXB2 levels and FEV1. The present findings suggest that cysteinyl LTs play a more important role in the pathogenesis of asthma than TXA2.

Adult↗
PubMed2000

A new thioether-ligated iron porphyrin as a model of a protonated form of P450 active site.

Thioether-ligated iron porphyrin (complex 1) was synthesized as a model of the protonated form of P450 to explore the possible involvement of the protonated form in the catalytic cycle, and ether-ligated iron porphyrin (complex 2) was also synthesized for comparison. The thioether and ether ligands enhanced heterolytic O-O bond cleavage of peroxy acid-iron porphyrin complex even in highly hydrophobic media without the assistance of acid or base, using mCPPAA as an oxidant. Competitive oxidation of cyclooctane/cyclooctene catalyzed by iron porphyrins showed that complexes 1 and 2 are less effective than heme thiolate (P450 and a synthetic heme thiolate (SR complex)) in oxidizing alkane. The possibility that thiol-ligated heme, which is a protonated form of heme thiolate, is not involved in the active intermediate structure of P450 is indicated by this result. This is the first report concerning the oxidizing ability of a thioether-ligated iron porphyrin.

Binding Sites↗