Search PubMed⌕ Search

Biomedical subjects

K Koike

Publications and source records attributed to K Koike.

At least 325 records · Page 18Linked to original sources
PubMed1996

Differentiation of binding sites of CGP12177, a beta 3-adrenoceptor partial agonist, and carteolol, a beta 1/beta 2-adrenoceptor partial agonist, to the beta-adrenoceptors in guinea-pig taenia caecum.

Differentiation of binding sites of CGP12177 and carteolol to the beta-adrenoceptors in the guinea-pig taenia caecum was investigated. Carteolol and CGP12177 competitively antagonized the relaxation responses to isoprenaline, and the pA2 values were 9.87 and 9.33, respectively. Butoxamine, a beta 2-selective antagonist, caused competitive antagonism of the relaxant responses to carteolol, and the pA2 value for butoxamine was 6.22. However, butoxamine (10(-4) M) did not significantly affect the relaxant responses to CGP12177. CGP12177 caused competitive antagonism of the relaxant responses to carteolol, and the pA2 value for CGP12177 was 9.32. However, carteolol (10(-6) M) did not significantly affect the relaxant responses to CGP12177. The competitive inhibition curve for specific binding of 50 nM [3H]befunolol by carteolol showed a biphasic shape, although the curve by CGP12177 was monophasic. Moreover, the competitive inhibition curve for specific binding of 100 nM [3H]CGP12177 by CGP12177 showed a biphasic shape, although the curve by carteolol indicated partial inhibition. These results suggest that the low affinity site of beta-adrenoceptor and beta 3-adrenoceptors are different from each other.

Adrenergic beta-Agonists↗
PubMed1996

[Long-term effect of a beta-adrenergic agonist on Na+/K(+)-ATPase activity in rat lung explants].

To test the long-term effect of a beta-adrenergic agonist on Na+/K(+)-ATPase activity in rat lung explants, we measured the activity in lung explants kept continuously in the presence or absence of 0.1 mM terbutaline for 5 days. Once it was clear that this agent increased Na+/K(+)-ATPase activity, we then performed a similar measurement in cultured alveolar type II cells from rats. Continuous exposure to 0.1 mM terbutaline enhanced the enzyme activity in those cells, and this enhancement was completely blocked by 0.01 mM of the beta-antagonist propranolol. Western blotting showed that this increase in Na+/ K(+)-ATPase activity in the cells could involve modulation of protein expression. We conclude that beta-adrenergic agonists can increase Na+/K(+)-ATPase activity in alveolar type II cell in lung explants by modulating expression of the enzyme in a long period of time.

Adrenergic beta-Agonists↗
PubMed1995

Superoxide dismutase in SAS human tongue carcinoma cell line is a factor defining invasiveness and cell motility.

This article describes an apparent inverse relationship between cell motility and intracellular Cu-Zn superoxide dismutase (SOD) activity of two human squamous carcinoma-derived clones, SAS-H1 with high invasiveness and SAS-L1 with low invasiveness. Clone SAS-H1 exhibited significantly greater motility than SAS-L1 but had significantly lower levels of intracellular Cu-ZnSOD than SAS-L1 cells. We then transfected Cu-ZnSOD antisense cDNA into SAS-L1 to reduce the intracellular Cu-ZnSOD activity. Antisense cDNA transfected SAS-L-AS clones had lower Cu-ZnSOD activity than control vector-transfected SAS-L-Neo clones, and this was associated with increased motility. Invasiveness of SAS-H1 and SAS-L-AS1 was enhanced by superoxide treatment, while the invasiveness of SAS-L1 was unaffected. These findings indicate that intracellular SOD is involved in cell motility by virtue of its action in scavenging superoxide in the cells.

Base Sequence↗
PubMed1995

Hepatitis C virus genotypes and development of hepatocellular carcinoma.

BACKGROUND: Among several genotypes of hepatitis C virus (HCV), genotypes 1b (or II) and 2a (or III) are predominant in Japan. Although it has been shown that the efficacy of interferon treatment of patients with chronic hepatitis C varies with the HCV genotype, the relationship between HCV genotype and the development of hepatocellular carcinoma (HCC) has not been well described. METHODS: The genotypes and serum levels were determined for HCV-RNA in 72 patients with HCC and 131 patients without HCC, all of whom were positive for second-generation HCV antibody and HCV-RNA. In addition, clinical data from 34 patients with HCC who each had a history of blood transfusion were analyzed. RESULTS: Fifty-seven (79.2%) of 72 patients with HCC had genotype 1b HCV, whereas 101 (77.1%) of 131 patients without HCC had genotype 1b, indicating that there was no significant difference in the prevalence of genotype 1b HCV between the patients with and without HCC. Furthermore, comparison of patients with HCC with genotype 1b HCV with those with genotype 2a who had a history of blood transfusion did not differ significantly in the number of years from blood transfusion to diagnosis of HCC. Levels of HCV-RNA were not significantly different among patients with liver diseases of various stages. CONCLUSIONS: Hepatocellular carcinoma develops in patients with either genotype 2a HCV or genotype 1b HCV. A difference in genotype is not likely to be responsible for the difference in development of HCC.

Carcinoma, Hepatocellular↗
PubMed1995

The gene encoding human 2-oxoglutarate dehydrogenase: structural organization and mapping to chromosome 7p13-p14.

Genomic clones covering the entire sequence of the gene encoding human 2-oxoglutarate dehydrogenase (OGDH) were isolated by screening leukocyte and placenta genomic libraries with radio- and digoxigenin (DIG)-labeled human OGDH cDNAs. The human OGDH gene contains 22 exons spanning approx. 85 kb. All exon/intron splice junctions follow the GT/AG rule. The results of primer extension analysis imply that the OGDH transcription start point is a thymine residue 55 bp upstream from the ATG start codon. The 5'-flanking region of OGDH lacked canonical TATA or CAAT boxes. Using DNAs from human x rodent somatic cell hybrids that segregate human chromosomes in conjunction with fluorescence in situ hybridization, human OGDH was assigned to chromosome arm 7p, an area that corresponds to the boundary between bands 7p13 and 7p14.

Amino Acid Sequence↗
PubMed1995

Receptor-mediated transfer of pSV2CAT DNA to a human hepatoblastoma cell line HepG2 using asialofetuin-labeled cationic liposomes.

Asialofetuin-labeled liposomes (AF-lps) were developed as a vector for gene transfer to hepatocytes. Plasmid pSV2CAT DNA which encodes bacterial chloramphenicol acetyltransferase (CAT) was associated with (meaning, in this report, the sum of 'to be adsorbed on the surface of' and 'to be encapsulated into the internal phase of') AF-lps (AF-lps-pSV2CAT) prepared by a tandem combination of the detergent removal and freeze-thaw methods. Ninety-six percent of input pSV2CAT was associated with AF-lps containing N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride, and approx. two-thirds of the associated DNA was encapsulated into the internal phase. The uptake of AF-lps by the cultured human hepatoblastoma cell line HepG2, having asialoglycoprotein receptors (AGPR) on their plasma membrane, was decreased by the addition of free AF and cytochalasin B. AF-lps bound to HepG2 cells through specific interaction with AGPR, and were internalized into the cells by the receptor-mediated endocytotic pathway. HepG2 cells transfected by AF-lps-pSV2CAT showed a significantly higher CAT activity than those transfected by pSV2CAT associated with non-labeled control lps (N-lps-pSV2CAT) or a mixture of pSV2CAT and empty AF-lps. Pretreatment with EDTA-encapsulated AF-lps increased the transfection efficiency of AF-lps-pSV2CAT. The CAT activity in A431 and Swiss/3T3 cells transfected with AF-lps-pSV2CAT was low and almost the same as those transfected with N-lps-pSV2CAT. Since DNA encapsulated in lps is likely to be protected against digestion by nucleases in the blood circulation, AF-lps could be used as a gene transfer vector targeting the hepatocytes in vivo.

Asialoglycoprotein Receptor↗
PubMed1995

Possible mechanisms of beta-adrenoceptor-mediated relaxation induced by noradrenaline in guinea pig taenia caecum.

The mechanisms of the beta-adrenoceptor-mediated relaxation induced by noradrenaline in guinea pig taenia caecum were investigated. Noradrenaline caused graded relaxation of this preparation. However, the concentration-response curves for noradrenaline were unaffected by propranolol (approximately 10(-5) M) or phentolamine (approximately 10(-5) M). The responses to noradrenaline were antagonized in a concentration-dependent manner by bupranolol, and Schild plots of the data revealed a pA2 value of 5.53. Also, bupranolol antagonized responses to isoprenaline, and Schild plots of the data revealed the pA2 value to be 8.53. Noradrenaline significantly increased the cyclic AMP level in this preparation. Bupranolol (10(-4) M) significantly decreased the cyclic AMP response elicited by noradrenaline, whereas propranolol (10(-5) M) produced no effect. These results suggest that the relaxant response to noradrenaline in guinea pig taenia caecum is mainly mediated by beta 3-adrenoceptors (or atypical beta-adrenoceptors) and that in guinea pig taenia caecum noradrenaline behaves as a beta 3-selective adrenoceptor agonist.

Adrenergic beta-Agonists↗
PubMed1995

Dominant replication of either virus in dual infection with hepatitis viruses B and C.

To characterize the state of dual infection with hepatitis B virus (HBV) and hepatitis C virus (HCV), HBV-DNA and HCV-RNA levels were determined by spot hybridization or polymerase chain reaction in the sera of patients who were positive for both hepatitis B surface antigen and HCV antibody. Among 27 patients who showed evidence of double infection, 21 (77.8%) had detectable levels of only either HBV or HCV genome in their sera, 2 (7.4%) showed none of the viral genomes, and 4 (14.8%) had both HBV-DNA and HCV-RNA. In the 4 patients with both HBV-DNA and HCV-RNA, the titers of HCV-RNA or HBV-DNA were lower than those in the patients with HCV-RNA or HBV-DNA alone. In some patients with chronic hepatitis, the viruses appeared to replicate in turn in the course of the disease. These results indicate that the viruses show alternating dominance in replication in most of the patients who have dual infection with HBV and HCV, probably due to interference of the viruses.

Adolescent↗
PubMed1995

PMNs primed for superoxide release and increased CD11b expression do not sequester in normal lung.

Our previous work has implicated platelet activating factor (PAF)-induced neutrophil (PMN) priming and increased CD11b/CD18 receptor expression in the pathogenesis of lung injury following gut ischemia/reperfusion (I/R). In this model CD11b blockade abrogates lung injury but does not alter PMN priming or pulmonary leukosequestration. We, therefore, hypothesized that PAF-stimulated PMN priming and CD11b expression are insufficient to promote lung PMN sequestration. Normal rat PMNs, labeled with 51Cr, were incubated with PAF (10 ng/ml) to induce priming for superoxide (O2-) generation and enhance CD11b expression. Gut I/R animals underwent superior mesenteric artery occlusion for 45 min. 51Cr-labeled PMNs (2 x 10(7)) were injected iv. Study groups, consisting of (a) normal/control, (b) sham/laparotomy, and (c) gut I/R, were given either normal or PAF-treated PMNs. PAF-primed PMNs had increased 2- release and CD11b expression, but did not sequester in the lungs of normal rats. However, following gut I/R PAF-treated PMNs sequestered in the pulmonary bed. These data suggest that PAF priming for O2- generation and increased CD11b expression are insufficient alone to promote PMN sequestration in the lung. Rather, additional factors generated by gut I/R are necessary for this process.

Animals↗
PubMed1995

Purification and properties of an alkaline protease from alkalophilic Bacillus sp. KSM-K16.

Alkaline protease (EC 3.4.21.14) activity, suitable for use in detergents, was detected in the alkaline culture medium of Bacillus sp. KSM-K16, which was originally isolated from soil. The enzyme, designated M protease, was purified to homogeneity from the culture broth by column chromatographies. The N-terminal amino acid sequence was Ala-Gln-Ser-Val-Pro-Trp-Gly-Ile-Ser-Arg- Val-Gln-Ala-Pro-Ala-Ala-His-Asn-Arg-Gly-Leu-Thr-Gly. The molecular mass of the protease was 28 kDa, and its isoelectric point was close to pH 10.6. Maximum activity toward casein was observed at 55 degrees C and at pH 12.3 in 50 mM phosphate/NaOH buffer. The activity was inhibited by phenylmethylsulfonyl fluoride and chymostatin. The enzyme was very stable in long-term incubation with liquid detergents at 40 degrees C. The enzyme cleaved the oxidized insulin B chain initially at Leu15-Tyr16 and efficiently at ten more sites. Among various oligopeptidyl p-nitro-anilides (pNA) tested, N-succinyl-Ala-Ala-Pro-Phe-pNA was efficiently hydrolyzed by M protease. M protease was precipitated in (NH4)2SO4-saturated acetate buffer (pH 5.0) as plank-like crystals.

Amino Acid Sequence↗
PubMed1995

Disruption of the function of tumor-suppressor gene p53 by the hepatitis B virus X protein and hepatocarcinogenesis.

The X gene of the hepatitis B virus codes for a small basic protein and is able to transactivate viral and cellular genes, although the X protein exhibits no DNA-binding activity. The mechanism of transactivation by X protein has been suggested to be via protein-protein interaction(s). We first demonstrated that X protein had amino acid sequences homologous to the functionally essential domain of Kunitz-type serine protease inhibitors and that those sequences were indispensable for the transactivation function. We demonstrated that X protein exhibited an inhibitor activity against hepatic serine proteases, and subsequently found that the protein activated X gene transcription in HepG2 cells and that the X responsive element was localized in the minimal promoter of the X gene. In contrast, the tumor-suppressor gene p53, but not mutant p53, remarkably reduced transcription from the minimal promoter. This p53 repression on the X gene promoter was cancelled by X gene co-expression, probably indicating that the X protein disrupts the p53 tumor suppressor function in the nucleus. All data suggest that X protein leads to transactivation of cellular oncogenes by preventing an interaction between p53 and cellular transcription factor(s) consisting of the basal transcriptional machinery.

Carcinoma, Hepatocellular↗
PubMed1995

Interleukin-6 stimulates cell proliferation of rat pituitary clonal cell lines in vitro.

We investigated the effect of recombinant human IL-6 (rhIL-6) on cell proliferation using the MtT/E rat pituitary tumor cell line, which was recently established by Inoue et al. This cell line expresses the homeodomain protein Pit-1/GHF 1 and does not produce any significant amount of pituitary hormones, but retains its tumorigenicity by back-transplantation into rats, resulting in production of prolactin. MtT/E cells were seeded into Falcon 24-well plates at a density of 2 x 10(4) cells/well in a cultured medium, containing 10% horse serum and 2.5% fetal bovine, with test drug. After four-days (12 days for the time-course study) incubations, the cells were counted using a hemocytometer. Incubation for 4 days with rhIL-6 caused concentration-dependent stimulation of MtT/E cell growth and [3H]-thymidine incorporation into MtT/E cells. Addition of 20 ng/ml rhIL-6 to the culture medium stimulated MtT/E cell growth in a time-dependent manner, withdrawal of rhIL-6 from the culture medium reduced MtT/E cell growth, and re-addition of rhIL-6 to the culture medium again stimulated MtT/E cell growth. Among the cytokines tested, granulocyte colony-stimulating factor (rh G-CSF) also showed a slight but significant mitogenic activity on the MtT/E cells. Analysis of 125I-rhIL-6 binding to the MtT/E cells indicated a dissociation constant of 0.953 x 10(-9) mmol/l and the presence of 968 binding sites per cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effect of bupranolol on CGP 12177-induced relaxation and cAMP accumulation in the guinea pig taenia caecum.

1. The effect of bupranolol on CGP 12177-induced relaxation and cAMP accumulation in the guinea pig taenia caecum was examined. 2. The relaxant response to CGP 12177 was unaffected by propranolol (approximately 10(-6) M), whereas that to CGP 12177 was antagonized in a concentration-dependent manner by bupranolol; Schild plot of the data revealed the pA2 value of 5.61. 3. CGP 12177 significantly increased cyclic AMP level in this preparation. Bupranolol (10(-4) M) significantly decreased the cyclic AMP level that was elicited by CGP 12177, whereas propranolol (10(-5) M) produced no effect. 4. These results suggest that bupranolol appears to be an efficient beta3-antagonist in the guinea pig taenia caecum and confirm that the response to CGP 12177 is mediated by beta3-adrenoceptors.

Adrenergic beta-Antagonists↗
PubMed1995

Antisense phosphorothioates as antivirals against human immunodeficiency virus (HIV) and hepatitis B virus (HBV).

For the past 10 years we have focused on the development of antisense treatments against viral infections such as human immunodeficiency virus (HIV) and hepatitis B virus (HBV). We have demonstrated that phosphorothioate oligomers have in vitro anti-HIV activities and in vivo anti-HBV activity. In vitro anti-HIV activities of phosphorothioate oligodeoxynucleotides (S-oligo) were classified into sequence non-specific (non-antisense) and sequence specific (antisense). We found that toxicity of S-oligo could be also classified into the same 2 categories. Since some of non-specific toxicity is dependent on experimental conditions, in each experiment, we should pay attention to minimize non-specific toxicity of the oligomers.

Animals↗
PubMed1995

Perimenopausal changes in serum lipids and lipoproteins: a 7-year longitudinal study.

Although cross-sectional studies suggest considerable influence of menopause on serum lipids and lipoproteins in women, it is not exactly clear. During our 7-year longitudinal study, serum concentrations of total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and low-density lipoprotein (LDL) cholesterol were measured in 16 healthy perimenopausal women (aged 47-56 years at menopause) who had undergone annual examinations 4 years before and 3 years after menopause under a health examinations system in Osaka. Longitudinal design enabled us to study the natural course of serum lipids and lipoproteins. The results show that from 4 years before to 1 year after menopause, the serum concentration of total cholesterol and LDL cholesterol increased on average by 25 mg/dl (14%) and 20 mg/dl (19%), respectively. Serum concentrations of triglycerides and of HDL cholesterol remained virtually unchanged during the perimenopausal and postmenopausal periods. It was concluded that serum lipids and lipoproteins are thus significantly altered as a consequence of menopause, resulting in a more atherogenic profile in the postmenopausal period.

Arteriosclerosis↗