Biomedical subjects

H Shibata

Publications and source records attributed to H Shibata.

At least 217 records · Page 12Linked to original sources

PubMed1997

Tamoxifen and chemotherapy for lymph node-negative, estrogen receptor-positive breast cancer.

BACKGROUND: The B-20 study of the National Surgical Adjuvant Breast and Bowel Project (NSABP) was conducted to determine whether chemotherapy plus tamoxifen would be of greater benefit than tamoxifen alone in the treatment of patients with axillary lymph node-negative, estrogen receptor-positive breast cancer. METHODS: Eligible patients (n = 2306) were randomly assigned to one of three treatment groups following surgery. A total of 771 patients with follow-up data received tamoxifen alone; 767 received methotrexate, fluorouracil, and tamoxifen (MFT); and 768 received cyclophosphamide, methotrexate, fluorouracil, and tamoxifen (CMFT). The Kaplan-Meier method was used to estimate disease-free survival, distant disease-free survival, and survival. Reported P values are two-sided. RESULTS: Through 5 years of follow-up, chemotherapy plus tamoxifen resulted in significantly better disease-free survival than tamoxifen alone (90% for MFT versus 85% for tamoxifen [P = .01]; 89% for CMFT versus 85% for tamoxifen [P = .001]). A similar benefit was observed in both distant disease-free survival (92% for MFT versus 87% for tamoxifen [P = .008]; 91% for CMFT versus 87% for tamoxifen [P = .006]) and survival (97% for MFT versus 94% for tamoxifen [P = .05]; 96% for CMFT versus 94% for tamoxifen [P = .03]). Compared with tamoxifen alone, MFT and CMFT reduced the risk of ipsilateral breast tumor recurrence after lumpectomy and the risk of recurrence at other local, regional, and distant sites. Risk of treatment failure was reduced after both types of chemotherapy, regardless of tumor size, tumor estrogen or progesterone receptor level, or patient age; however, the reduction was greatest in patients aged 49 years or less. No subgroup of patients evaluated in this study failed to benefit from chemotherapy. CONCLUSIONS: Findings from this and other NSABP studies indicate that patients with breast cancer who meet NSABP protocol criteria, regardless of age, lymph node status, tumor size, or estrogen receptor status, are candidates for chemotherapy.

Antimetabolites, Antineoplastic↗

PubMed1997

Rapid colorectal adenoma formation initiated by conditional targeting of the Apc gene.

Familial adenomatous polyposis coli (FAP) is a disease characterized by the development of multiple colorectal adenomas, and affected individuals carry germline mutations in the APC gene. With the use of a conditional gene targeting system, a mouse model of FAP was created that circumvents the embryonic lethality of Apc deficiency and directs Apc inactivation specifically to the colorectal epithelium. loxP sites were inserted into the introns around Apc exon 14, and the resultant mutant allele (Apc580S) was introduced into the mouse germline. Mice homozygous for Apc580S were normal; however, upon infection of the colorectal region with an adenovirus encoding the Cre recombinase, the mice developed adenomas within 4 weeks. The adenomas showed deletion of Apc exon 14, indicating that the loss of Apc function was caused by Cre-loxP-mediated recombination.

Adenomatous Polyposis Coli↗

PubMed1997

A high-resolution PAC and BAC map of the SCA2 region.

The spinocerebellar ataxia type 2 (SCA2) gene has been localized to chromosome 12q24.1. To characterize this region and to aid in the identification of the SCA2 gene, we have constructed a 3.9-Mb physical map, which covers markers D12S1328 and D12S1329 known to flank the gene. The map comprises a contig of 84 overlapping yeast artificial chromosomes (YACs), P1 artificial chromosomes (PACs), and bacterial artificial chromosomes (BACs) onto which we placed 82 PCR markers. We localized eight genes and expressed sequence tags on this map, many of which had not been precisely mapped before. In contrast to YACs, which showed a high degree of chimerism and deletions in this region, PACs and BACs were stable. Only 1 in 65 PACs contained a small deletion, and 2 in 18 BACs were chimeric. The high-resolution physical map, which was used in the identification of the SCA2 gene, will be useful for the positional cloning of other disease genes mapped to this region.

Ataxins↗

PubMed1997

An oocyte-specific methylation imprint center in the mouse U2afbp-rs/U2af1-rs1 gene marks the establishment of allele-specific methylation during preimplantation development.

An oocyte-specific methylation imprint mark region, consisting of approximately 200 bp from the mouse imprinted gene U2afbp-rs, was identified within an area containing a CpG island and a short tandem repeat sequence. The oocyte-specific methylation was preserved in fertilized eggs and then expanded on the repressed maternal allele during preimplantation development until the adult methylation pattern was achieved by 12.5 days of embryonic development. These results indicate that the oocyte-specific imprinting mark region acts as a center in establishing the hypermethylated region on the repressed maternal allele. Furthermore, a region that is hypermethylated in both gametes was identified but its hypermethylation was conserved only on the maternal allele during preimplantation development, suggesting that some factor(s) inherited from oocytes may act to maintain hypermethylation on the maternal allele.

Alleles↗

PubMed1997

Substituted 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase.

A series of 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives have been synthesized and evaluated for their ability to selectively inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The 1-phenyl moiety participates in a hydrophobic interaction where an optimum size is required. At this position, 3,4-dimethylphenyl is the best moiety for inhibiting chymase and showed high selectivity compared with chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrogen-bond acceptors such as nitrile and methoxycarbonyl enhances its activity. Molecular-modeling studies on the interaction of 3-[(4-chlorophenyl)sulfonyl]-1-(4-chlorophenyl)-imidazolidine-2,4-dione (29) with the active site of human heart chymase suggested that the 1-phenyl moiety interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, and the 4-carbonyl of the imidazolidine ring and sulfonyl group interact with the oxyanion hole and the His-45 side chain of chymase, respectively. The complex model is consistent with the structure-activity relationships.

Binding Sites↗

PubMed1997

Antioxidant activity of polyphenolics in diets. Rate constants of reactions of chlorogenic acid and caffeic acid with reactive species of oxygen and nitrogen.

Phenolic non-flavonoid compounds in diets, such as chlorogenic acid and caffeic acid are widely recognized to be antioxidants. However, it is not known how these phenolics scavenge reactive species of oxygen and nitrogen. We determined the rate constants of the reactions between the phenolics with superoxide and hydroxyl radical with a pulse radiolysis. The second-order rate constants of the reactions of chlorogenic acid with superoxide and hydroxyl radical were 1.67 +/- 0.14 x 10(6) M(-1) s(-1) and 3.34 +/- 0.19 x 10(9) M(-1) s(-1), respectively, while those of caffeic acid with superoxide and hydroxyl radical were 0.96 +/- 0.01 x 10(6) M(-1) s(-1) and 3.24 +/- 0.12 x 10(9) M(-1) s(-1), respectively. By scavenging peroxy radical chlorogenic acid inhibited the initiation of chain lipid peroxidations by organic free radical. The second-order rate constant of the reaction of chlorogenic acid with peroxy radical was estimated to be 1.28 +/- 0.11 x 10(5) M(-1) s(-1). Chlorogenic acid was rapidly oxidized by peroxynitrite in concentration- and pH-dependent manners and its rate constant was determined to be 1.6 +/- 0.7 x 10(5) M(-1) s(-1), using competitive inhibitions by glutathione and methionine.

Antioxidants↗

PubMed1997

Insulin stimulates guanine nucleotide exchange on Rab4 via a wortmannin-sensitive signaling pathway in rat adipocytes.

Rab4, a member of the Rab family of Ras-related small GTP-binding proteins, has been shown to be associated with GLUT4-containing vesicles and implicated in the insulin action on glucose transport in rat adipocytes. In the present study, we investigated the insulin effects on the guanine nucleotide exchange on Rab4. In electrically permeabilized rat adipocytes, the amount of [35S]guanosine 5'-O-(3-thiotrisphosphate) (GTPgammaS) bound to Rab4 increased in a time-dependent manner during 45 min of the incubation period. Addition of insulin resulted in about a 2-fold stimulation of the binding of [35S]GTPgammaS to Rab4, indicating that insulin stimulated the guanine nucleotide exchange on the GTPase. Pretreatment of the cells with wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase, completely abolished the stimulatory effect of insulin on [35S]GTPgammaS binding to Rab4. Wortmannin also attenuated the nucleotide binding to Rab4 in the basal cells, suggesting that phosphatidylinositol 3-kinase activity may be essential for regulation of guanine nucleotide exchange on the GTPase and insulin may up-regulate the exchange activity by stimulating the lipid kinase. Insulin-induced subcellular redistribution of Rab4 from the microsomal fraction to the soluble fraction was also inhibited by wortmannin. These results suggest that insulin stimulates the guanine nucleotide exchange on Rab4 via a phosphatidylinositol 3-kinase-dependent signaling pathway and that Rab4 is one of possible targets of insulin action on intracellular vesicle traffic in rat adipocytes.

3-O-Methylglucose↗

PubMed1997

Domain-specific phosphorylation of vimentin and glial fibrillary acidic protein by PKN.

PKN is a serine/threonine protein kinase with a catalytic domain homologous to the protein kinase C family and unique N-terminal leucine zipper-like sequences. Using analyses with the yeast two-hybrid system and in vitro binding assay, we found that the regulatory domain of PKN interacted with vimentin. We then examined whether PKN would phosphorylate vimentin in vitro. Vimentin proved to be an excellent substrate for PKN, and the phosphorylation of vimentin by PKN occurred in the head domain with the result of a nearly complete inhibition of its filament formation in vitro. Similar results were also obtained with another type III intermediate filament protein, glial fibrillary acidic protein (GFAP). These results raise the possibility that PKN may regulate filament structures of vimentin and GFAP by domain-specific phosphorylation.

Animals↗

PubMed1997

Gene expression of subunit c(P1), subunit c(P2), and oligomycin sensitivity-conferring protein may play a key role in biogenesis of H+-ATP synthase in various rat tissues.

Mammalian H+-ATP synthase is a supramolecule composed of at least 14 subunits that have a constant stoichiometry. Nevertheless the coordinate regulation of the gene expressions of various subunits remains obscure. To clarify the coordinate transcriptional regulatory system of mammalian H+-ATP synthase, we determined the absolute amount of nine species of mRNAs for eight nuclear-encoded subunits of H+-ATP synthase in different tissues of 8-week-old rats by use of the synthetic mRNAs and 32P-labeled DNA probes for each mRNA. Our quantitative analyses of the transcripts of H+-ATP synthase revealed that nine species of the subunits in different tissues of 8-week-old rats were divisible into two groups: a high transcript gene (HTG) group (beta-subunit, subunit b, subunit d, subunit e, and Factor 6) and a low transcript gene (LTG) group (subunit c(P1), subunit c(P2), IF1, and oligomycin sensitivity-conferring protein). The transcription step of LTG could constitute a bottleneck in the biogenesis of H+-ATP synthase. Thus, the transcriptional regulatory system of the LTG may play a key role in the biogenesis of mammalian H+-ATP synthase. The HTG were transcribed in a tissue-specific manner that corresponds with energy demand in the tissues. However, there was no tissue specificity in subunit c(P2). Furthermore, the tissue specificity of the transcript of IF1 differed substantially from that of HTG, suggesting that it could be crucial in the protection of mitochondrial membrane under abnormal conditions.

Animals↗

PubMed1997

Interaction of PKN with alpha-actinin.

PKN is a fatty acid- and Rho-activated serine/threonine protein kinase, having a catalytic domain homologous to protein kinase C family. To identify components of the PKN-signaling pathway such as substrates and regulatory proteins of PKN, the yeast two-hybrid strategy was employed. Using the N-terminal region of PKN as a bait, cDNAs encoding actin cross-linking protein alpha-actinin, which lacked the N-terminal actin-binding domain, were isolated from human brain cDNA library. The responsible region for interaction between PKN and alpha-actinin was determined by in vitro binding analysis using the various truncated mutants of these proteins. The N-terminal region of PKN outside the RhoA-binding domain was sufficiently shown to associate with alpha-actinin. PKN bound to the third spectrin-like repeats of both skeletal and non-skeletal muscle type alpha-actinin. PKN also bound to the region containing EF-hand-like motifs of non-skeletal muscle type alpha-actinin in a Ca2+-sensitive manner and bound to that of skeletal muscle type alpha-actinin in a Ca2+-insensitive manner. alpha-Actinin was co-immunoprecipitated with PKN from the lysate of COS7 cells transfected with both expression constructs for PKN and alpha-actinin lacking the actin-binding domain. In vitro translated full-length alpha-actinin containing the actin-binding site hardly bound to PKN, but the addition of phosphatidylinositol 4, 5-bisphosphate, which is implicated in actin reorganization, stimulated the binding activity of the full-length alpha-actinin with PKN. We therefore propose that PKN is linked to the cytoskeletal network via a direct association between PKN and alpha-actinin.

Actinin↗

PubMed1997

Activation of a calcium-permeable cation channel CD20 expressed in Balb/c 3T3 cells by insulin-like growth factor-I.

CD20 functions as a calcium-permeable cation channel. When expressed in Balb/c 3T3 cells, CD20 accelerates the G1 progression induced by insulin-like growth factor-I (IGF-I). To further characterize how CD20 modulates the action of IGF-I, we investigated whether the activity of CD20 channel was affected by IGF-I. In quiescent cells expressing CD20, IGF-I increased cytoplasmic free calcium concentration, [Ca2+]c, which was reversed by the removal of extracellular calcium. In contrast, IGF-I did not increase [Ca2+]c in cells that did not express CD20. In perforated patch clamp recordings, addition of IGF-I to the bath solution augmented the Ca2+ permeability, which was reversed by anti-CD20 antibody. In cell-attached patch, calcium-permeable channel activity with unitary conductance of 7 picosiemens was detected, which was abolished by anti-CD20 antibody. The single channel activities were markedly enhanced when IGF-I was included in the pipette solution, whereas IGF-I added to the bath solution was ineffective. When cells were first exposed to pertussis toxin, activation of the channel by IGF-I was blocked. Transfection of cDNA for Gip2, a constitutive active form of alphai2, activated the CD20 channel. These results indicate that the CD20 channel is regulated by the IGF-I receptor by a mechanism involving pertussis toxin-sensitive G protein.

3T3 Cells↗

PubMed1997

Assessment of the role of activin A and transforming growth factor beta in the regulation of AML12 cell growth.

The present study was conducted to determine the role of two autocrine factors, activin A and transforming growth factor beta (TGF-beta), in the growth regulation of AML12 hepatocytes. We overexpressed truncated type II activin and/or TGF-beta receptors in AML12 cells. In AML12 cells overexpressing truncated type II activin receptors (AML-tAR cells), the inhibitory effect of activin A on DNA synthesis was completely blocked. AML-tAR cells proliferated faster than parental cells, both in the presence and absence of epidermal growth factor (EGF). However, AML-tAR cells could not grow in soft agar. Follistatin augmented EGF-induced DNA synthesis in AML12 cells, whereas it was ineffective in AML-tAR cells. In AML12 cells overexpressing truncated type II TGF-beta receptor (AML-tTR cells), the inhibitory effect of TGF-beta on DNA synthesis was blocked. AML-tTR cells proliferated faster than parental cells, both in the presence and absence of EGF, but at a slower rate than that of AML-tAR cells. AML-tTR cells did not grow in soft agar. The growth rate of cells overexpressing both types of truncated receptors was identical to that of AML-tAR cells, and these cells did not grow in soft agar. These results indicate that both activin A and TGF-beta act as autocrine inhibitors of DNA synthesis in AML12 cells, and that the blocking of the actions of two factors does not lead to transformation. Activin A is a predominant autocrine factor in these cells.

Activin Receptors↗

PubMed1997

Successful combined resection of carcinoma of the esophagus and adrenal metastasis: report of a case.

We report herein the case of a 56-year-old man who underwent successful combined resection of carcinoma of the esophagus and an adrenal metastasis. The patient presented with carcinoma of the thoracic esophagus, and an adrenal tumor was incidentally detected by computed tomography(CT). Complete removal of the carcinoma was accomplished along with a combined resection of the thoracic esophagus and left adrenal gland. Surgery was followed by the administration of anticancer chemotherapeutic agents. He is currently doing well with a grade 1 performance status and no signs of recurrence 22 months after his operation. To our knowledge, no previous report of the successful simultaneous resection of esophageal carcinoma and an adrenal metastasis has been documented in the literature.

Adrenal Gland Neoplasms↗

PubMed1997

Distribution of ABO genotypes and allele frequencies in a Korean population.

The genotypes of the ABO blood group system were investigated in Korean living in Kangwon-Do area by PCR-RFLP analysis of the seven polymorphic nucleotide positions 261, 467, 526, 646, 703, 796 and 803 of the cDNA from A1 transferase. In 253 unrelated Korean individuals, 15 genotypes were found and the allele frequencies of A(Pro), A(Leu), B, O(T) and O(A) were 0.022, 0.209, 0.209, 0.360 and 0.200, respectively, with no deviation from Hardy-Weinberg expectations (chi 2 = 2.145, d.f. = 6, 0.90 < p < 0.95). As for the distribution of allele frequencies, a significant difference was noticed between the Korean and a Japanese (chi 2 = 30.87, d.f. = 4, p < 0.001) and a German (chi 2 = 127.76, d.f. = 4, p < 0.001) populations.

ABO Blood-Group System↗

PubMed1997

Inhibition of proliferation of MCF-7 breast cancer cells by a blocker of Ca(2+)-permeable channel.

In MCF-7 breast cancer cells, insulin-like growth factor-1 (IGF-1) increased the calcium-permeability of the cells by activating a voltage-independent calcium-permeable channel. IGF-1 also induced oscillatory elevation of cytoplasmic free calcium concentration in these cells. An anti-allergic compound, tranilast, reduced the calcium-permeability augmented by IGF-1 in a dose-dependent manner and blocked the oscillatory elevation of cytoplasmic free calcium concentration. Tranilast did not affect early intracellular signals activated by IGF-1, including receptor autophosphorylation, activations of Ras, mitogen-activated protein kinase and phosphatidylinositol 3-kinase. Tranilast inhibited increases in [3H]-thymidine incorporation, DNA content and cell number induced by IGF-1. The ID50 for [3H]-thymidine incorporation and DNA content were about 10 microM. The inhibitory effect of tranilast was reversible, and cell viability was not affected. Treatment with tranilast increased the number of cells in the G1 phase suggesting that this compound induced G1 arrest. Tranilast also reduced the phosphorylation of the retinoblastoma protein. These results indicate that tranilast inhibits the IGF-1-induced cell growth in MCF-7 cells by blocking calcium entry.

Breast Neoplasms↗

PubMed1997

Effects of hydralazine on responses to histamine and caffeine in ileal longitudinal muscle and taenia coli of the guinea pig.

1. The mechanism of tension inhibitory effects on histamine and caffeine-induced responses by hydralazine were studied in the ileal longitudinal muscle and taenia coli of the guinea-pig. Hydralazine, 10(-4) to 3 x 10(-3) M, inhibited both the tonic response and the increase in Ca uptake by the lanthanum (La) method evoked by histamine (10(-5) M) without affect on Ca efflux, with smaller effects on the phasic response in ileal muscle. 2. Hydralazine suppressed caffeine- and IP3-induced contractions after loading with Ca2+ into the storage sites in saponin-treated fibers. However, hydralazine suppressed the caffeine- and IP3-induced contractions in the skinned fibers relatively less than both the transient response to caffeine and phasic response to histamine in intact muscles, respectively. 3. It is probable that hydralazine reduces the tonic response to histamine mainly by inhibiting Ca2+ influx through receptor operated Ca2+ channels in the ileum. In addition, hydralazine also decreases caffeine- or IP3-induced Ca2+ release from storage sites.

Animals↗

PubMed1997

Factor VIII gene analysis in Japanese CRM-positive and CRM-reduced haemophilia A patients by single-strand conformation polymorphism.

Haemophilia A is the most common X-linked blood coagulation disorder; it is caused by deficiency of factor VIII activity (FVIII:C). Half of the affected patients do not have detectable levels of FVIII protein in their plasma, whereas about 5% have normal levels of the FVIII antigen (FVIII:Ag) (> 50 u/dl), and are called cross-reacting material (CRM) positive (CRM+ or A+). About 45% of patients have reduced levels of the FVIII:Ag (1-50 u/dl), classified as CRM reduced (CRM[R] or A[R]). We screened the FVIII gene of 13 Japanese patients (five CRM+ and eight CRM[R]) by single-strand conformation polymorphism, and identified 11 different mutations in 13 patients by analysing all 26 exons (Trp255Cys, Tyr473Cys, Gly479Arg, Arg531His, Thr667Arg, Arg1689Cys, Arg1941Gln, Arg2150His, Arg2159Cys, Thr2245Ala and Gly2285Val). Seven mutations were identified in the A domains (four in the A2 domain). All the mutations are point mutations resulting in missense codons. Four mutations (Trp255Cys, Thr667Arg, Thr2245Ala and Gly2285Val) have not been described previously.

Enzyme-Linked Immunosorbent Assay↗

PubMed1997

Further analysis of Del (D-elute) using polymerase chain reaction (PCR) with RHD gene-specific primers.

Del (D-elute) in the Rh blood group system is a variant with very weak D antigen and no agglutination is found by the indirect antiglobulin test. This variant is characterized by the presence of anti-D eluate obtained after an adsorption-elution test using anti-D antibodies. We studied here the molecular genetic status of Del by using polymerase chain reaction with sequence-specific primers (PCR-SSP). We screened 306 serologically apparent D-negative Japanese donors comprising 102 Del types for exons 7, 4 and 10 of the RHD gene. No PCR product was found in all 204 non-Del samples from the D-seronegative donors. However, PCR products were found in all 102 Del samples and all 70 D-seropositive samples tested by the three PCR methods for exons 7, 4 and 10 analysis. Del was found with CCee, CcEe and Ccee, but not with CCEe, CcEE, ccEE, ccEe or ccee phenotype. The incidences of Del in the samples with the serological phenotypes CCee, CcEe and Ccee were 80.0% (4/5), 68.2% (45/66) and 61.6% (53/86), respectively. The results provide evidence that Del samples have exons 4, 7 and 10 of an RHD gene present in some form. This is consistent with the evidence that D antigen is present on the cells although only detected by antibody adsorption and elution. The PCR-SSP method in the present study is useful to confirm Del among serologically apparent D-negative samples.

Asian People↗