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Biomedical subjects

N Shimizu

Publications and source records attributed to N Shimizu.

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

Wpkci, encoding an altered form of PKCI, is conserved widely on the avian W chromosome and expressed in early female embryos: implication of its role in female sex determination.

Two W chromosome-linked cDNA clones, p5fm2 and p5fm3, were obtained from a subtracted (female minus male) cDNA library prepared from a mixture of undifferentiated gonads and mesonephroi of male or female 5-d (stages 26-28) chicken embryos. These two clones were demonstrated to be derived from the mRNA encoding an altered form of PKC inhibitor/interacting protein (PKCI), and its gene was named Wpkci. The Wpkci gene reiterated approximately 40 times tandemly and located at the nonheterochromatic end of the chicken W chromosome. The W linkage and the moderate reiteration of Wpkci were conserved widely in Carinatae birds. The chicken PKCI gene, chPKCI, was shown to be a single-copy gene located near the centromere on the long arm of the Z chromosome. Deduced amino acid sequences of Wpkci and chPKCI showed approximately 65% identity. In the deduced sequence of Wpkci, the HIT motif, which is essential for PKCI function, was absent, but the alpha-helix region, which was conserved among the PKCI family, and a unique Leu- and Arg-rich region, were present. Transcripts from both Wpkci and chPKCI genes were present at significantly higher levels in 3- to 6-d (stages 20-29) embryos. These transcripts were detected in several embryonic tissues, including undifferentiated left and right gonads. When the green fluorescent protein-fused form of Wpkci was expressed in male chicken embryonic fibroblast, it was located almost exclusively in the nucleus. A model is presented suggesting that Wpkci may be involved in triggering the differentiation of ovary by interfering with PKCI function or by exhibiting its unique function in the nuclei of early female embryos.

Amino Acid Sequence↗
PubMed2000

Stimulation of prostaglandin E2 and interleukin-1beta production from old rat periodontal ligament cells subjected to mechanical stress.

Although the severity of periodontal disease is known to be affected by the age of the host, the pathological role of aging in periodontal disease, especially that attributable to trauma from occlusion, has not been well characterized. Prostaglandin (PG)E2 and interleukin (IL)-1beta are key mediators involved in periodontal diseases, potent stimulators of bone resorption, and are produced by human periodontal ligament (PDL) cells in response to mechanical stress. To investigate age-related changes in the biosynthetic capacity of PGE2 and IL-1beta in PDL cells, we examined the effects of in vivo aging with mechanical tension on PGE2 and IL-1beta expression by rat PDL cells. PDL cells obtained from the incisors of 6-week (young) and 60-week (old) rats were cultured on flexible-bottomed culture plates. The cells were deformed by causing a 9% or 18% increase in surface area at 6 cycles per minute for 1 to 5 days. We found an approximately twofold increase in PGE2 and IL-1beta production by old PDL cells subjected to mechanical tension compared with that by young cells, although the constitutive levels were similar in both. The expression of cyclooxygenase (COX)-2 and IL-1beta mRNA (messenger ribonucleic acid) was enhanced by mechanical tension as determined by use of reverse transcription-polymerase chain reaction (RT-PCR), whereas COX-1 and IL-1beta-converting enzyme mRNA remained unchanged. It is possible that the large amount of PGE2 and IL-1beta produced by PDL cells from an aged host in response to mechanical force may be positively related to the acceleration of alveolar bone resorption.

Aging↗
PubMed2000

Local recurrence of renal cell carcinoma causing massive gastrointestinal bleeding: a report of two patients who underwent surgical resection.

We report two cases of local recurrence of renal cell carcinoma, which invaded the gastrointestinal tract. The intervals to local recurrence after primary nephrectomies were 5 and 13 years. Both cases developed massive gastrointestinal bleeding. Blood transfusions and arterial embolization were performed; however, continuous melena prevented improvement in their general condition. Although distant metastases were observed in both cases, tumor resections combined with intestine invasion were performed. Although this surgical approach does not significantly improve the prognosis, even in patients who have remaining metastatic lesions, it may provide palliation and improve the quality of survival.

Aged↗
PubMed2000

A putative G protein-coupled receptor, RDC1, is a novel coreceptor for human and simian immunodeficiency viruses.

More than 10 G protein-coupled receptors (GPCRs) have been shown to act as coreceptors for infection of human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV). We have isolated HIV-1 variants infectious to primary brain-derived CD4-positive cells (BT-3 and BT-20/N) and U87/CD4 glioma cells that are resistant to T-cell line-tropic (T-tropic), macrophage-tropic (M-tropic), and T- and M-tropic (dualtropic) (X4, R5, and R5X4) HIV-1 strains. These primary brain-derived cells were also highly susceptible to HIV-2(ROD), HIV-2(SBL6669), and SIV(mndGB-1). A factor or coreceptor that determines the susceptibility of these brain-derived cells to these HIV and SIV strains has not been fully identified. To identify this coreceptor, we examined amino acid sequences of all known HIV and SIV coreceptors and noticed that tyrosine residues are well conserved in their extracellular amino-terminal domains. By this criterion, we selected 18 GPCRs as candidates of coreceptors for HIV and SIV strains infectious to these brain-derived cells. mRNA expression of an orphan GPCR, RDC1, was detected in the brain-derived cells, the C8166 T-cell line, and peripheral blood lymphocytes, all of which are susceptible to HIV-1 variants, but not in macrophages, which are resistant to them. When a CD4-expressing cell line, NP-2/CD4, which shows strict resistance to infection not only with HIV-1 but also with HIV-2 or SIV, was transduced with the RDC1 gene, the cells became highly susceptible to HIV-2 and SIV(mnd) strains but to neither M- nor T-tropic HIV-1 strains. The cells also acquired a low susceptibility to the HIV-1 variants. These findings indicate that RDC1 is a novel coreceptor for several HIV-1, HIV-2, and SIV strains which infect brain-derived cells.

Animals↗
PubMed2000

Increased expression of insulin-like growth factor I in skin in amyotrophic lateral sclerosis.

OBJECTIVES: Insulin-like growth factor I (IGF-I) has potent effects on motor neuron survival and is being studied as a possible therapeutic agent for ALS. However, little is known concerning IGF-I in the skin of patients with amyotrophic lateral sclerosis (ALS). The aim was to evaluate IGF-I immunoreactivity of skin in patients with ALS. METHODS: IGF-I immunoreactivity of skin from 18 patients with ALS and 16 controls was examined. RESULTS: IGF-I immunoreactivity was markedly positive in the epidermis and dermal blood vessels and glands and was moderately positive in the reticular dermis in all patients with ALS. On the other hand, the epidermis and dermal blood vessels and glands and the reticular dermis showed a weak IGF-I immunoreactivity in controls. The optical density for IGF-I immunoreactivity of the epidermis and dermal blood vessels and glands, and the reticular dermis in patients with ALS was significantly higher than in diseased controls, and was significantly increased with duration of illness. CONCLUSIONS: These data suggest that a metabolic alteration of IGF-I may take place in the skin of patients with ALS.

Aged↗
PubMed2000

Pentoxifylline accelerates gastric ulcer healing in rats: roles of tumor necrosis factor alpha and neutrophils during the early phase of ulcer healing.

BACKGROUND/AIMS: Pentoxifylline has many anti-inflammatory properties including inhibition of production of tumor necrosis factor alpha (TNF-alpha). Although pentoxifylline prevents several types of gastric mucosal injury, the effect of this drug on ulcer healing is unknown. In this study, we examined the effect of pentoxifylline on healing of acetic acid induced gastric ulcers in rats. METHODS: Rats with gastric ulcer received an intraperitoneal injection of 10 mg/kg pentoxifylline once daily for 14 days or for only the first 7 days or the last 7 days of the 14-day treatment period. Some rats were given antirat neutrophil antiserum intraperitoneally every other day. Ulcer size, myeloperoxidase activity, and concentration and location of TNF-alpha in ulcer tissue were assessed. RESULTS: Administration of pentoxifylline for 14 days or for the first 7 days, but not for the last 7 days, of the 14-day treatment period accelerated ulcer healing. TNF-alpha was detected mainly in monocytes/macrophages and in some neutrophils at ulcer bases and margins. Pentoxifylline markedly decreased the concentration of TNF-alpha as well as the myeloperoxidase activity in ulcer tissue on days 2 and 4. Antirat neutrophil antiserum inhibited neutrophil infiltration into ulcer tissue and accelerated ulcer healing. CONCLUSION: Pentoxifylline accelerates healing of acetic acid induced gastric ulcer in rats. This effect may be due in part to reduction of neutrophil infiltration and inhibition of production of TNF-alpha by inflammatory cells. Early-phase inhibition of inflammatory response may accelerate ulcer healing.

Acetic Acid↗
PubMed2000

Increased expression of laminin 1 in the skin of amyotrophic lateral sclerosis.

Abnormalities of collagen and glycosaminoglycans of skin have been reported in patients with amyotrophic lateral sclerosis (ALS). However, little is known concerning laminin in ALS. The aim of this study is to evaluate laminin 1 immunohistochemistry of skin in ALS patients. We studied laminin 1 immunoreactivity of skin from 17 patients with ALS, 17 patients with other neurological or muscular diseases (control group A) and 10 patients without neurological or muscular disorders (control group B). The dermis, the epithelial basement membrane of the epidermal layer and the basement membrane of skin appendages and blood vessels of skin in ALS patients were significantly higher than in control groups A and B, and showed a significant positive correlation with the duration of illness in the optical density for laminin 1 immunoreactivity. In addition, there was an appreciable positive relationship in the laminin 1 immunoreactivity between the dermis and the basement membrane in ALS patients. These data suggest that alterations of laminin 1 in the skin of ALS patients could be related to the pathogenesis of ALS and may contribute to changes in the mechanical properties of the skin, resulting in the absence of bedsores in ALS patients.

Adult↗
PubMed2000

Serum markers of type I collagen synthesis and degradation in amyotrophic lateral sclerosis.

Collagen abnormalities in the skin and spinal cord have been reported in amyotrophic lateral sclerosis (ALS) patients. Serum carboxyterminal propeptide of type I procollagen (PICP) and the carboxyterminal cross-linked telopeptide of type I collagen (ICTP) reflect type I collagen synthesis and degradation, respectively. However, there has been no study concerning PICP or ICTP in ALS. We studied collagen contents of the skin and measured serum levels of PICP and ICTP in patients with ALS and control subjects. Serum PICP levels were significantly lower in ALS patients than in controls. Serum ICTP levels were significantly higher in ALS patients than in controls, and there was an appreciable positive correlation between serum ICTP levels and the duration of illness in ALS patients. In ALS patients, the collagen content of the skin was significantly smaller than in controls and indicated a progressive decrease in relation to illness. In addition, there was a significant negative correlation between serum ICTP concentrations and the collagen content of the skin in ALS patients. These data suggest that increased ICTP levels and decreased serum PICP levels may reflect unique changes in the skin, with a predominance of degradation compared to the synthesis of type I collagen in ALS.

Adult↗
PubMed2000

Thrombin stimulates pertussis toxin-sensitive and -insensitive GTPase activities and ADP-ribosylation of G(i) in human neuroblastoma SH-EP.

Kinetic interaction between thrombin receptor and G proteins was investigated in human epithelial neuroblastoma cell line, SH-EP. In these cells, both alpha-thrombin and SFLLRNP (one-letter amino-acid code) stimulated GTPase activity and enhanced cholera toxin-catalyzed ADP-ribosylation of G(i2) in a concentration-dependent manner. Basal GTPase activity was attenuated by pertussis toxin treatment by 35%, however, agonist stimulation was preserved significantly. These results together indicated that thrombin receptor simultaneously activates G(i2) and PTX-insensitive G protein(s).

Adenosine Diphosphate Ribose↗
PubMed2000

Overexpression of truncated IkappaBalpha induces TNF-alpha-dependent apoptosis in human vascular smooth muscle cells.

Dysregulation of apoptosis is one of the likely underlying mechanisms of neointimal thickening, a disorder in which proinflammatory cytokines may influence the function of vascular smooth muscle cells (VSMCs) and contribute to atherogenesis. One of these cytokines, tumor necrosis factor-alpha (TNF-alpha), induces 2 possibly conflicting pathways, 1 leading to the activation of nuclear factor-kappaB (NF-kappaB) and the other leading to caspase-mediated apoptosis. We investigated whether specific inhibition of NF-kappaB affects TNF-alpha-dependent apoptosis in human VSMCs. To inhibit NF-kappaB activation specifically, we constructed a recombinant adenovirus vector expressing a truncated form of the inhibitor protein IkappaBalpha (AdexIkappaBDeltaN) that lacks the phosphorylation sites essential for activation of NF-kappaB. The IkappaBDeltaN was overexpressed by adenoviral infection and was resistant to stimulus-dependent degradation. Electromobility gel shift and luciferase assays demonstrated that overexpression of IkappaBDeltaN inhibited NF-kappaB activation induced by TNF-alpha or interleukin-1beta (IL-1beta). In cells overexpressing IkappaBDeltaN, TNF-alpha dramatically induced apoptosis, whereas IL-1beta had no effect. The induction was suppressed by treatment with a selective inhibitor of the caspase-3 family, Z-DEVD-fmk, and the overexpression of IkappaBDeltaN induced TNF-alpha-mediated caspase-3 and caspase-2 activity. These results indicate that overexpression of IkappaBDeltaN induces TNF-alpha-dependent apoptosis by efficient and specific suppression of NF-kappaB and upregulation of caspase-3 and caspase-2 activity in human VSMCs. Our findings suggest that adenovirus-mediated IkappaBDeltaN gene transfer may be useful in the treatment of disorders associated with inflammatory conditions, such as the response to vascular injury and atherosclerosis.

Adenoviridae↗
PubMed2000

Cardiotrophin-1 increases angiotensinogen mRNA in rat cardiac myocytes through STAT3 : an autocrine loop for hypertrophy.

-Cardiotrophin-1, an interleukin-6-related cytokine, stimulates the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway and induces cardiac myocyte hypertrophy. In this study, we demonstrate that cardiotrophin-1 induces cardiac myocyte hypertrophy in part by upregulation of a local renin-angiotensin system through the JAK/STAT pathway. We found that cardiotrophin-1 increased angiotensinogen mRNA expression in cardiac myocytes via STAT3 activation. Tyrosine phosphorylation of STAT3 by cardiotrophin-1 treatment resulted in STAT3 homodimer binding to the St-domain in the angiotensinogen gene promoter, which lead to promoter activation in a transient transfection assay. Cardiotrophin-1-induced STAT3 tyrosine phosphorylation and binding to the St-domain were suppressed by AG490, a specific JAK2 inhibitor, which also attenuated cardiotrophin-1-stimulated angiotensinogen promoter activity. Cardiotrophin-1 did not activate the angiotensinogen gene promoter that contained a substitution mutation within the St-domain. Finally, losartan, an angiotensin II type 1 receptor antagonist, significantly attenuated cardiotrophin-1-induced hypertrophy of neonatal rat cardiac myocytes. Angiotensin II is known to induce cardiac myocyte hypertrophy by activating the G-protein-coupled angiotensin II type 1 receptor. Our results suggest that upregulation of angiotensinogen and angiotensin II production contribute to cardiotrophin-1-induced cardiac myocyte hypertrophy and emphasize an important interaction between G-protein-coupled and cytokine receptors.

Angiotensin Receptor Antagonists↗
PubMed2000

Evaluating the role of inducible nitric oxide synthase using a novel and selective inducible nitric oxide synthase inhibitor in septic lung injury produced by cecal ligation and puncture.

We studied the role of inducible nitric oxide synthase (iNOS) in septic lung injury using a novel and selective iNOS inhibitor (a fused piperidine derivative; ONO-1714) following a cecal ligation and puncture (CLP) procedure. All rats that received CLP died within 48 h after the intervention. The subcutaneous injection of ONO-1714 at 0.03 mg/kg every 12 h resulted in a significantly longer survival time than the saline control only when administration was started 12 h after the CLP procedure. The other administration schedules, which started immediately or 6 h after the intervention, did not show any improvement in the survival rates in comparison with the saline control. The administration of ONO-1714 at higher (0.1 mg/ kg) or lower (0.01 mg/kg) doses when given anytime after the intervention did not improve the survival rates. The NO(x) (NO(2)(-) + NO(3)(-)) levels in the plasma significantly increased 12 h after intervention in comparison with NO(x) at 0 h and thereafter further increased in parallel with the time elapsed. The CLP rats that were initially treated with ONO-1714 (0.03 mg/kg subcutaneously every 12 h) 12 h after intervention showed significantly reduced NO(x) levels in the plasma in comparison with the saline control. The NO synthase activity in lung homogenates increased from 6 to 24 h after the CLP and thereafter decreased to 42 h. The administration of ONO-1714 inhibited iNOS activity (under calcium-free conditions) in preference to total iNOS activity (under calcium-dependent conditions) in lung homogenates, which thus suggested that this compound selectively inhibited iNOS in lung tissue. The iNOS protein expression in the lung and liver homogenates showed a similar time course with alterations of NOS activity, namely a maximum level at 24 h after the intervention followed by decreasing levels to 42 h. On the other hand, other isozymes of NOS, eNOS, and nNOS in lung homogenates, were constantly expressed over the time course after the CLP. Since the iNOS mRNA expression in lung homogenates continued to elevate until 42 h, the decrease in iNOS activity and protein expression later than 24 h after the CLP was thus considered to be due to some posttranscriptional mechanism during the late phase of sepsis. In conclusion, intervention with a potent and selective iNOS inhibitor seemed to improve survival in CLP rats when used at the appropriate doses and time points. However, the self-limited mechanism of iNOS regulation in the lungs may also indicate that iNOS plays only a limited role in sepsis and septic shock.

Amidines↗
PubMed2000

Induced detachment of acentric chromatin from mitotic chromosomes leads to their cytoplasmic localization at G(1) and the micronucleation by lamin reorganization at S phase.

Acentric and atelomeric double minute chromatin found in human cancer cells are eliminated from cells by selective incorporation into the micronuclei. We showed previously that most of the micronuclei were formed at S phase and mediated by the nuclear bud-shaped structures that selectively entrap double minutes. In this paper, we have examined the behavior of double minutes in relation to the nuclear lamin protein in cell cycle-synchronized human COLO 320DM tumor cells. At the G(1) phase, we observed that a portion of double minutes was localized at the cytoplasm and showed no association with lamin. The frequency of this localization was increased by hydroxyurea, an inducer of micronuclei, if treated at the preceding S phase. The acentric double minutes were normally segregated to daughter cells by attaching to the mitotic chromosomes, and the hydroxyurea-treatment induced their detachment, possibly through the introduction of the double strand break. When the cells entered S phase, our data suggested that the lamin protein accumulated around the cytoplasmic double minutes at the proximity of the nucleus leading to the formation of the nuclear bud-shaped structure and the initiation of DNA replication. This association of cytoplasmic double minutes with lamin coincided with the large-scale rearrangement of the intranuclear lamin protein. The implication of these findings as well as their application to a broad spectrum of other acentric, atelomeric and autonomously replicating molecules are discussed.

Chromatin↗
PubMed2000

Influence of N-terminal peptide and oligosaccharide on the clearance of t-PA.

We have studied the influence of Gly-Ala-Arg peptide at the N-terminus and the oligosaccharide at Asn184 on the clearance of tissue plasminogen activator (t-PA). In order to intensify the influence of these structural features, Gln117 t-PA, which is a mutant tissue plasminogen activator (mt-PA) expressed in mouse C127 cells, was used for the investigation. It is altered to remove a high mannose type oligosaccharide by the mutation of an amino acid from Asn117 to Gln. We isolated 4 variants of Gln117 t-PA by cation-exchange chromatography, which are abbreviated as S-I, S-II, L-I and L-II. These variants originated from the heterogeneity of the peptide chains (S-chain, 527 amino acids, L-chain, 530 amino acids) and oligosaccharide (Type I, 2 oligosaccharides, Type II, 1 oligosaccharide). Pharmacokinetics of these variants were investigated after single intravenous administration to male rats at a dose of 250 microg/kg. Significant differences in pharmacokinetic parameters were observed among these variants, but there was no considerable difference in fibrin clot lysis time (FCLT) activity. Gly-Ala-Arg peptide at the N-terminus increased the CLt, whereas the oligosaccharide at Asn184 decreased the CLt. Moreover, the effects of the N-terminal peptide and the oligosaccharide on the CLt were independent of each other. Our study with Gln117 t-PA revealed the role of the N-terminal peptide found in the L-chain produced during the processing of t-PA precursor.

Animals↗
PubMed2000

Ardisimamillosides C-F, four new triterpenoid saponins from Ardisia mamillata.

Four new triterpenoid saponins, ardisimamilloside C (1), 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)-[beta -D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]-3beta,16al pha,28,30-tetrahydroxy-olean-12-en, ardisimamilloside D (2), 3-O-¿alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)-[beta -D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]-3beta,15al pha,28,30-tetrahydroxy-olean-12-en, ardisimamilloside E (3), 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)-[beta -D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosl]-13beta,2 8-epoxy-3beta,16alpha,29-oleananetriol, and ardisimamilloside F (4), 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)-[beta -D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]-3beta,16al pha-dihydroxy-13beta,28-epoxy-oleanan-30-oic acid were isolated from the roots of Ardisia mamillata Hance. Structure assignments were established on the basis of highresolution (HR)-FAB-MS, 1H-, 13C-, and two-dimensional (2D)-NMR spectra, and on the chemical evidence.

Carbohydrate Conformation↗
PubMed2000

Lysyl-tRNA synthetase of Bacillus stearothermophilus molecular cloning and expression of the gene.

The gene of the lysyl-tRNA synthetase of Bacillus stearothermophilus NCA1503 was cloned and sequenced. The gene consists of 1485 bp nucleotides commencing with an ATG start codon and ending with a TAA stop codon, and encodes a polypeptide of 493 amino acids. The recombinant enzymes were expressed in E. coli using an expression plasmid containing the T7 RNA polymerase/promoter.

Amino Acid Sequence↗
PubMed2000

Effect of addition of Orvus ES paste to frozen canine semen extender on sperm acrosomes.

Using the triple-stain technique, we investigated whether sperm acrosomes in frozen canine semen were protected during freezing and thawing by addition of a surfactant, Orvus ES Paste (OEP), to the extender. Acrosomes were clearly shown to be protected by the addition of OEP to the entender when compared with those in sperm frozen without OEP addition (p<0.05).

Acrosome↗