Search PubMed⌕ Search

Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 253 records · Page 14Linked to original sources
PubMed2000

Downregulation of intracellular nm23-H1 prevents cisplatin-induced DNA damage in oesophageal cancer cells: possible association with Na(+), K(+)-ATPase.

Previously, we showed that expression of nm23-H1 is associated inversely with sensitivity to cisplatin in human oesophageal squamous cell carcinoma (OSCC). The present study was undertaken to investigate the association of nm23-H1 expression with cisplatin-induced DNA damage in OSCC using antisense nm23-H1 transfectants. YES-2/AS-12, an antisense nm23-H1-transfected OSCC cell line, showed significantly reduced expression of intracellular nm23-H1 protein compared with that in parental YES-2 cells and YES-2/Neo transfectants. Surface expression of nm23-H1 protein was not observed in any of the three cell lines. PCR analysis for DNA damage demonstrated that YES-2/AS-12 cells were more resistant to nuclear and mitochondrial DNA damage by cisplatin than were YES-2/Neo cells. In addition, mitochondrial membrane potentials and DNA fragmentation assays confirmed that YES-2/AS-12 was more resistant than YES-2/Neo to apoptosis induced by cisplatin. In contrast, YES-2/AS-12 was more sensitive to ouabain, a selective inhibitor of Na(+), K(+)-ATPase, than YES-2 and YES-2/Neo. Pre-treatment with ouabain resulted in no differences in cisplatin sensitivity between the three cell lines examined. Intracellular platinum level in YES-2/AS-12 was significantly lower than that in YES-2 and YES-2/Neo following incubation with cisplatin, whereas ouabain pre-treatment resulted in no differences in intracellular platinum accumulations between the three cell lines. Our data support the conclusion that reduced expression of intracellular nm23-H1 in OSCC cells is associated with cisplatin resistance via the prevention of both nuclear and mitochondrial DNA damage and suggest that it may be related to Na(+), K(+)-ATPase activity, which is responsible for intracellular cisplatin accumulation.

Antineoplastic Agents↗
PubMed2000

Superiority of a new UICC-TNM staging system for gastric carcinoma.

BACKGROUND: The definition of the degree of lymph node metastasis (n-classification) for gastric cancer differs greatly in the new Union Internationale Contre le Cancer--TNM classification (5th edition) and the Japanese gastric cancer classification (JGC). The feasibility of the new TNM classification is evaluated in comparison with the JGC. METHODS: At Chiba University, 940 patients who underwent a gastrectomy were retrospectively classified into appropriate stages with both the TNM and JGC systems, and the survival curves of the respective stages were also compared. RESULTS: Patients with 1 to 6 metastatic nodes (TNM-pN1) showed similar survival rates whether the metastases were limited to the perigastric area (JGC-n1) or reached distant areas (JGC-n2). The patients with node metastasis that was limited to the perigastric area (JGC-n1) had significantly different survival rates, depending on the number of metastatic nodes (TNM-pN1 or pN2, P = .022). A similar phenomenon was also observed in patients with TNM-N2 and JGC-n2. A multivariate analysis indicated the TNM N-classification, rather than the JGC n-classification, as an independent prognostic factor. CONCLUSIONS: The new TNM classification appears to be a better prognostic indicator than the JGC system for patients with gastric carcinoma.

Female↗
PubMed2000

Clinical benefits of steroid therapy on surgical stress in patients with esophageal cancer.

BACKGROUND: Despite improvements in surgical techniques and perioperative care, severe complications lead to long hospital stays for some esophageal cancer patients. The purpose of this study was to evaluate the safety and effectiveness of perioperative steroid therapy on the postoperative clinical course. METHODS: Fifty-seven patients operated for esophageal cancer in 1997 and 1998 were treated with perioperative steroid therapy. Fifty consecutive patients operated in 1995 and 1996 served as a control group. In the steroid group, each patient was given 250 mg of methylprednisolone intravenously before operation followed by 125 mg on postoperative days 1 and 2. Serum interleukin-6, polymorphonuclear cell elastase, and C-reactive protein levels, and the postoperative clinical course were compared between the groups. RESULTS: Morbidity rates including hyperbilirubinemia, anastomotic leakage, and liver dysfunction were significantly lower in the steroid group than in the control group. Days until extubation and hospital stay were significantly shorter for the steroid group. Inflammatory mediators, body temperature, heart rate, and respiratory index after the surgical procedure were significantly lower in the steroid group. Adverse effects possibly caused by steroid therapy were not observed. CONCLUSIONS: Perioperative steroid therapy was safe and effective for the inhibition of inflammatory mediators and the improvement of the postoperative clinical course of patients with esophageal cancer.

Acute-Phase Proteins↗
PubMed2000

Symptomatic peripheral vascular tree stenosis. Comparison of subtracted and nonsubtracted 3D contrast-enhanced MR angiography with fat suppression.

OBJECTIVE: To determine the clinical feasibility of contrast-enhanced three-dimensional (3D) MR angiography (MRA) with fat suppression spectral inversion at lipids and to compare subtracted and nonsubtracted images. MATERIAL AND METHODS: In 13 patients suspected of having lower extremity ischemia, 3D dynamic contrast-enhanced MRA of the iliac and femoral arteries was performed using the fat suppression technique. The validity of the MRA interpretations of the degree of stenoses was evaluated by comparing with conventional angiography as the gold standard. The contrast-to-noise (C/N) ratios of both subtracted and nonsubtracted maximum-intensity-projection (MIP) images were calculated. RESULTS: In the arteries with stenosis of 50% or greater, the sensitivity and specificity of the subtracted MR angiograms were 100% and 96.5%, respectively, not significantly different from the corresponding values in nonsubtracted MRAs (100% and 94.1%, respectively). The C/N ratios of the subtracted images were significantly higher than those of the nonsubtracted images (p<0.001). CONCLUSION: With this technique, fat suppression can be performed with only a slight increase in the examination time. A lower dose of contrast material can be used in MRA with fat suppression than without it. Subtracted MRA improves the ease of interpretation compared to nonsubtracted MRA.

Aged↗
PubMed2000

Endotoxin and cytokine regulation of toll-like receptor (TLR) 2 and TLR4 gene expression in murine liver and hepatocytes.

Toll-like receptor (TLR) 2 and TLR4 are members of the interleukin-1 receptor (IL-1R) family and transduce similar signals as IL-1R in response to bacteria and bacterial components. In this study, we investigated the regulation of their gene expression in murine tissues, especially in the liver and hepatocytes. When mice were administered lipopolysaccharide (LPS), TLR2 mRNA was upregulated in the brain, heart, lung, liver, and kidney. In contrast, it was downregulated in the spleen. TLR4 mRNA was decreased in the brain. In the heart and lung, it increased, and it was not affected in the liver, kidney, and spleen. TLR mRNA was further analyzed in the liver and hepatocytes. Like LPS treatment, administration of IL-1, IL-6, or tumor necrosis factor (TNF) upregulated TLR2 mRNA. However, none of them affected the TLR4 mRNA level. In primary cultured hepatocytes, TLR2 mRNA was upregulated by LPS, IL-1, or TNF but not by IL-6 or dexamethasone. None of them affected TLR4 mRNA expression. Similar responses were observed in the murine hepatoma cell line Hepa 1-6. These results suggest that in infection with gram-negative bacteria, LPS and proinflammatory cytokines differentially regulate gene expression of TLR2 and TLR4 in murine hepatocytes, which may lead to pathologic and host defense reactions in the liver.

Animals↗
PubMed2000

Stereospecific synthesis of alpha-anomeric pyrimidine nucleoside.

A facile stereospecific synthetic method for alpha-anomeric 2'-deoxypyrimidine nucleoside unit utilizing aminooxazoline derivative of ribofuranose was investigated. Thus, easily accessible riboaminooxazoline derivative prepared by ribose and cyanamid was allowed to react with ethyl alpha-bromoethylacrylate to give corresponding adduct. The adduct was cyclized by strong base such as potassium t-butokiside. The resulted 2,2'-cyclonucleoside was then treated with acetyl bromide followed by n-butyltin hydride to give alpha-anomeric 3',5'-di-O-acetylthymidine. 3',5'-Di-O-acety groups of the nucleoside were easily removed by the action of excess of triethyl amine in methanol. Essentially same procedure afforded corresponding 2'-deoxyuridine, which was further, converted to alpha-anomeric 2'-deoxycytidine.

Deoxycytidine↗
PubMed2000

Inhibitory effect of insulin on bradykinin-induced venodilation.

BACKGROUND: Excessive insulin is one of the risk factors of hypertension and arteriosclerosis despite its vasodilative properties shown in recent studies. Although many vasoactive substances contribute and interact with each other in the development of hypertension, the interactions between insulin and other vasoactive substances have yet to be elucidated. OBJECTIVE: To assess the effect of insulin on the action of bradykinin. METHODS: The vasodilating effect of bradykinin was evaluated, with or without coadministration of insulin, in human dorsal hand veins of healthy volunteers. In cultured porcine aortic endothelial cells, the bradykinin-induced increase of intracellular calcium was also investigated before and after insulin administration. RESULTS: Insulin significantly attenuated bradykinin-induced increase in intracellular calcium and venodilation in cultured endothelial cells and human dorsal hand veins, respectively. CONCLUSIONS: These findings suggest that insulin attenuates the bradykinin-induced calcium elevation in endothelial cells and may decrease the production of vasodilative substances from endothelial cells, resulting in the reduction of vasodilation. This effect may contribute to the development of hypertension in patients with hyperinsulinaemia.

Adult↗
PubMed2000

Effects of a selective inhibitor of Na+/Ca2+ exchange, KB-R7943, on reoxygenation-induced injuries in guinea pig papillary muscles.

The effects of a novel agent that is reported to selectively block Ca2+ influx by Na+/Ca2+ exchange (NCX), KB-R7943, on the reoxygenation-induced arrhythmias and the recovery of developed tension after reoxygenation, were investigated in guinea pig papillary muscles. KB-R7943 dose-dependently suppressed the contracture tension during low-sodium (21.9 mM) perfusion (23+/-8% of steady-state developed tension at 10 microM vs. 56+/-11% in control; n = 6, p<0.05), but did not change action potential and contractile parameters. During the reoxygenation period after 60-min substrate-free hypoxia, KB-R7943 (10 microM) significantly decreased the incidence of arrhythmias (44 vs. 100% in control; n = 9, p <0.05) and shortened the duration of arrhythmias (16+/-11 vs. 72+/-14 s; p<0.01). KB-R7943 (10 microM) significantly enhanced the recovery of developed tension after reoxygenation (83+/-4 vs. 69+/-3% in control; p<0.05). We conclude that KB-R7943 (10 microM) selectively inhibits the reverse mode of NCX, and that it attenuates reoxygenation-induced arrhythmic activity and prevents contractile dysfunction in guinea pig papillary muscles. These results suggest that Ca2+ influx by NCX may play a key role in reoxygenation injury.

Action Potentials↗
PubMed2000

Effects of an endothelin receptor antagonist TAK-044 on myocardial energy metabolism in ischemia/reperfused rat hearts.

The purpose of this study was to investigate the effects of an endothelin-receptor antagonist TAK-044 on functional defects and metabolic derangement in myocardial ischemia/reperfusion injury. We sequentially measured high-energy phosphate metabolites and intracellular pH by phosphorus magnetic resonance spectroscopy during 35-min global ischemia followed by 60-min reperfusion in Langendorff-perfused rat hearts. TAK-044 (initial loading by 3 mg/kg followed by perfusion with 100 nM solution) was administered in two different ways: before ischemia or immediately after reperfusion. In addition, we investigated the effects of TAK-044 on functional defects and metabolic alterations induced by hydrogen peroxide (200 microM, 30 min). The recoveries of left ventricular developed pressure after reperfusion in TAK-044 groups (51 +/-12% in TAK-I, 61 +/- 12% in TAK-R) were better than in control (10 +/- 5% in control; p < 0.01). Increases in left ventricular end-diastolic pressure (LVEDP) in TAK-044 groups (22 +/- 5 mm Hg in TAK-I, 24 +/- 5 mm Hg in TAK-R) were less than in control (38 +/- 3 mm Hg; p < 0.01). Adenosine triphosphate (ATP) (33 +/- 5% in TAK-I, 28 +/- 4% in TAK-R) in TAK-044 groups were higher than in control (13 +/- 3%; p < 0.01). The creatine phosphokinase (CPK) release during reperfusion in TAK-044 groups (3.3 +/- 1.5 IU/g wet wt/60 min in TAK-I, 3.5 +/- 2.5 IU/g wet wt/60 min in TAK-R) were lower than in control (13.8 +/- 3.9 IU/g wet wt/60 min; p < 0.05). In contrast, TAK-044 did not attenuate the myocardial injury induced by hydrogen peroxide. TAK-044, even if administered simultaneous with coronary reperfusion, attenuated myocardial ischemia/ reperfusion injury. The energy-preservative effect of TAK-044 could be associated with the good functional recovery in ischemia/reperfused rat hearts.

Animals↗
PubMed2000

Purification and characterization of a novel pumpkin short-chain acyl-coenzyme A oxidase with structural similarity to acyl-coenzyme A dehydrogenases.

A novel pumpkin (Cucurbita pepo) short-chain acyl-coenzyme A (CoA) oxidase (ACOX) was purified to homogeneity by hydrophobic-interaction, hydroxyapatite, affinity, and anion-exchange chromatography. The purified enzyme is a tetrameric protein, consisting of apparently identical 47-kD subunits. The protein structure of this oxidase differs from other plant and mammalian ACOXs, but is similar to the protein structure of mammalian mitochondrial acyl-CoA dehydrogenase (ACDH) and the recently identified plant mitochondrial ACDH. Subcellular organelle separation by sucrose density gradient centrifugation revealed that the enzyme is localized in glyoxysomes, whereas no immunoreactive bands of similar molecular weight were detected in mitochondrial fractions. The enzyme selectively catalyzes the oxidation of CoA esters of fatty acids with 4 to 10 carbon atoms, and exhibits the highest activity on C-6 fatty acids. Apparently, the enzyme has no activity on CoA esters of branched-chain or dicarboxylic fatty acids. The enzyme is slightly inhibited by high concentrations of substrate and it is not inhibited by Triton X-100 at concentrations up to 0.5% (v/v). The characteristics of this novel ACOX enzyme are discussed in relation to other ACOXs and ACDHs.

Acyl-CoA Dehydrogenase↗
PubMed2000

Genetic analysis of the ycgJ-metB-cysK-ygaG operon negatively regulated by the VirR/VirS system in Clostridium perfringens.

The 5'-flanking region of the metB-cysK-ygaG operon, whose expression is negatively regulated by the VirR/VirS system in C. perfringens, was analyzed. The region contained the ycgJ, mscL, and colA genes encoding a hypothetical protein, a large conductance mechanosensitive channel protein, and kappa-toxin (collagenase), respectively. Northern analysis revealed that the ycgJ gene was transcribed as a 4.9-kb operon together with the metB-cysK-ygaG genes and that this operon was negatively regulated by the VirR/VirS system. It is indicated that the pfoA (theta-toxin or perfringolysin O), colA, and ycgJ-metB-cysK-ygaG genes that belong to the VirR/VirS regulon are situated very close together in a 26.5-kb region of the chromosome, but do not form a pathogenic island.

Bacterial Proteins↗
PubMed2000

Isolation and characterization of monoclonal antibodies that inhibit hepatitis C virus NS3 protease.

A series of mouse monoclonal antibodies (MAbs) to the nonstructural protein 3 (NS3) of hepatitis C virus was prepared. One of these MAbs, designated 8D4, was found to inhibit NS3 protease activity. This inhibition was competitive with respect to the substrate peptide (K(i) = 39 nM) but was significantly decreased by the addition of the NS4A peptide, a coactivator of the NS3 protease. 8D4 also showed marked inhibition of the NS3-dependent cis processing of the NS3/4A polyprotein but had virtually no effect on the succeeding NS3/4A-dependent trans processing of the NS5A/5B polyprotein in vitro. Epitope mapping of 8D4 with a random peptide library revealed a consensus sequence, DxDLV, that matched residues 79 to 83 (DQDLV) of NS3, a region containing the catalytic residue Asp-81. Furthermore, synthetic peptides including this sequence were shown to block the ability of 8D4 to bind to NS3, indicating that 8D4 interacts with the catalytic region of NS3. The data showing decreased inhibition potency of 8D4 against the NS3/4A complex suggest that 8D4 recognizes the conformational state of the protease active site caused by the association of NS4A with the protease.

Amino Acid Sequence↗
PubMed2000

Myelodysplastic syndrome with clonal eosinophilia accompanied by eosinophilic pulmonary interstitial infiltration.

We report a case of de novo myelodysplastic syndrome with clonal eosinophilia (MDS-Eo) and eosinophilic pulmonary interstitial infiltration, confirmed by autopsy. Cytogenetic study using Giemsa banding identified 47,XY,+1,der(1;7)(q10;p10),+8 in the marrow cells. Simple Giemsa staining revealed the same chromosomal aberration in metaphase spreads with eosinophilic granules, indicating the clonal proliferation of eosinophils. To our knowledge, our case is the 6th reported case of MDS-Eo with cytogenetically confirmed clonal eosinophilia, and the first autopsy of MDS-Eo. A review of the literature combined with our findings suggests that this type of chromosomal aberration might be involved in the as yet unknown pathogenesis of MDS-Eo.

Aged↗
PubMed2000

Suppressive effect of topically applied CX-659S, a novel diaminouracil derivative, on the contact hypersensitivity reaction in various animal models.

BACKGROUND: The T-cell-mediated contact hypersensitivity reaction (CHR) is thought to be involved in the pathogenesis of clinical cutaneous disorders including atopic dermatitis. A novel diaminouracil derivative, CX-659S, has been reported to have an inhibitory activity against picryl chloride (PC)-induced CHR when administered either orally or percutaneously. The inhibitory effect of topical CX-659S was assessed in three CHR models in the present study. In addition, to elucidate the mechanism of action of this compound, we examined the effect of CX-659S on the expression of messenger RNAs for proinflammatory cytokines after elicitation in PC models. METHODS: For the in vivo evaluation of the efficacy of CX-659S, we used PC- or oxazolone-induced CHR in mice and 2,4-dinitrochlorobenzene (DNCB)-induced CHR in guinea pigs. CX-659S was topically applied immediately after the hapten challenge in each model. To assess the effect on gene expression of cytokines, we used the reverse transcriptase-polymerase chain reaction (RT-PCR), a semiquantitative technique with specific primers. RESULTS: Topical CX-659S dose-dependently inhibited ear swelling at 24 h after the challenge in the two mouse models. This inhibitory effect was histologically confirmed in the PC model. Topically applied CX-659S also inhibited erythema and edema formation 24 h after challenge in the guinea pig model. CX-659S inhibited the expression of mRNA for proinflammatory cytokines IL-1 beta and TNF-alpha in vivo. CONCLUSIONS: Topically applied CX-659S showed significant inhibitory activities against CHR models both in mice and in guinea pigs. Inhibition profiles of CX-659S toward mRNA expression for proinflammatory cytokines corroborated these findings. CX-659S thus could be a useful therapeutic agent for allergic cutaneous disorders such as allergic contact dermatitis and atopic dermatitis.

Administration, Topical↗
PubMed2000

Morphological aspects of the postnatal development of submandibular glands in male rats: involvement of apoptosis.

We studied the involvement of the apoptotic mechanism(s) in cell differentiation in the developing male rat submandibular gland using the TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-labeling) assay in combination with light and electron microscopy. Whereas the proacinar cells were completely transformed into acinar cells within 2 weeks after birth, starting on postnatal Day 21, the terminal tubule cells formed vacuoles that disappeared by postnatal Day 35. During this period, positive TUNEL reactivity was seen in the terminal tubule cells, and electron microscopic analysis showed that certain morphological features of apoptosis, including fragmentation of nuclei and the presence of apoptotic bodies in the cytoplasm, were present in and restricted to the terminal tubule cells. These results indicate that, in addition to an autophagocytosis-mediated mechanism, apoptosis may also be involved in reducing the number of terminal tubule cells during postnatal development in the submandibular gland.

Animals↗
PubMed2000

Basic helix-loop-helix transcription factors regulate the neuroendocrine differentiation of fetal mouse pulmonary epithelium.

To clarify the mechanisms that regulate neuroendocrine differentiation of fetal lung epithelia, we have studied the expression of the mammalian homologs of achaete-scute complex (Mash1) (Ascl1 - Mouse Genome Informatics); hairy and enhancer of split1 (Hes1); and the expression of Notch/Notch-ligand system in the fetal and adult mouse lungs, and in the lungs of Mash1- or Hes1-deficient mice. Immunohistochemical studies revealed that Mash1-positive cells seemed to belong to pulmonary neuroendocrine cells (PNEC) and their precursors. In mice deficient for Mash1, no PNEC were detected. Hes1-positive cells belong to non-neuroendocrine cells. In the mice deficient in Hes1, in which Mash1 mRNA was upregulated, PNEC appeared precociously, and the number of PNEC was markedly increased. NeuroD (Neurod1 - Mouse Genome Informatics) expression in the lung was detected in the adult, and was enhanced in the fetal lungs of Hes1-null mice. Expression of Notch1, Notch2, Notch3 and Notch4 mRNAs in the mouse lung increased with age, and Notch1 mRNA was expressed in a Hes1-dependent manner. Notch1, Notch2 and Notch3 were immunohistochemically detected in non-neuroendocrine cells. Moreover, analyses of the lungs from the gene-targeted mice suggested that expression of Delta-like 1 (Dll1 - Mouse Genome Informatics) mRNA depends on Mash1. Thus, the neuroendocrine differentiation depends on basic helix-loop-helix factors, and Notch/Notch-ligand pathways may be involved in determining the cell differentiation fate in fetal airway epithelium.

Aging↗
PubMed2000

Selective reduction of dormant maternal mRNAs in mouse oocytes by RNA interference.

Specific mRNA degradation mediated by double-stranded RNA (dsRNA), which is termed RNA interference (RNAi), is a useful tool with which to study gene function in several systems. We report here that in mouse oocytes, RNAi provides a suitable and robust approach to study the function of dormant maternal mRNAs. Mos (originally known as c-mos) and tissue plasminogen activator (tPA, Plat) mRNAs are dormant maternal mRNAs that are recruited during oocyte maturation; translation of Mos mRNA results in the activation of MAP kinase. dsRNA directed towards Mos or Plat mRNAs in mouse oocytes effectively results in the specific reduction of the targeted mRNA in both a time- and concentration-dependent manner. Moreover, dsRNA is more potent than either sense or antisense RNAs. Targeting the Mos mRNA results in inhibiting the appearance of MAP kinase activity and can result in parthenogenetic activation. Mos dsRNA, therefore, faithfully phenocopies the Mos null mutant. Targeting the Plat mRNA with Plat dsRNA results in inhibiting production of tPA activity. Finally, effective reduction of the Mos and Plat mRNA is observed with stoichiometric amounts of Mos and Plat dsRNA, respectively.

Animals↗