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Biomedical subjects

H Kohno

Publications and source records attributed to H Kohno.

At least 181 records · Page 10Linked to original sources
PubMed1995

Induction in the gene RNR3 in Saccharomyces cerevisiae upon exposure to different agents related to carcinogenesis.

The induction of the gene RNR3 was investigated in yeast Saccharomyces cerevisiae using RNR31 lacZ fusion. Gene induction was monitored by measuring beta-galactosidase activity. Various drugs that cause DNA damage effectively induced RNR3 expression; alkylating agents (cisplatin, mitomycin C and N-methyl-N'-nitro-N-nitrosoguanidine), a radical producer (bleomycin), and an intercalator (actinomycin D) induced RNR3. When yeast expressing rat CYP1A1 was exposed to 2-aminofluorene, a concentration-dependent induction of RNR3 was observed. Aflatoxin B1 also induced the expression of RNR3 in the same yeast strain concomitant with inhibition of cell growth. In control yeast, no induction of RNR3 was observed upon exposure to 2-aminofluorene or aflatoxin B1. Exposure to 2-acetylaminofluorene or benzo[a]pyrene did not lead to induction of RNR3 in yeast expressing CYP1A1. These results indicate that DNA damage by chemicals related to carcinogenesis induces RNR3, and that activation of these procarcinogens was required for DNA damage-dependent induction of RNR3.

Animals↗
PubMed1995

The human protoporphyrinogen oxidase gene (PPOX): organization and location to chromosome 1.

We determined the structure of the human protoporphyrinogen oxidase (PPOX) gene after isolation and characterization of lambda phage clones mapping discrete regions of the cDNA. Southern blotting of human genomic DNA showed that there is a single copy of the PPOX gene, and fluorescence in situ hybridization to metaphase chromosomes mapped the gene to region 1q22. The gene has 13 exons and about 8 kb. The exon/intron boundary sequences conform to consensus acceptor (GTn) and donor (nAG) sequences, and exons in the gene appear to encode functional protein domains. Primer extension analysis revealed two major transcriptional initiation sites in a region with sequence motifs characteristic of a promoter. The promoter region contains multiple Sp1 elements, CCAAT boxes, and potential GATA-1 binding sites. Mapping of the 5' end PPOX mRNA by polymerase chain reaction indicated that there are the same transcripts in erythroid and nonerythroid cells.

Bacteriophage lambda↗
PubMed1995

Nitric oxide-mediated inactivation of mammalian ferrochelatase in vivo and in vitro: possible involvement of the iron-sulphur cluster of the enzyme.

To investigate the role of the iron-sulphur cluster in mammalian ferrochelatases, the terminal enzyme of the haem biosynthetic pathway, we examined the interaction of nitric oxide (NO) and ferrochelatase. When macrophage cell line RAW 264.7 cells were treated with interferon-gamma and lipopolysaccharide NO synthesis in the cells was stimulated, and a decrease in ferrochelatase activity was observed, with no change in the amount of ferrochelatase. The addition of NG-monomethyl-L-arginine, a selective inhibitor of NO synthesis, reduced the effect of interferon-gamma and lipopolysaccharide, while the effect of NG-monomethyl-L-arginine was suppressed by the addition of L-arginine, a substrate of NO synthase. When purified recombinant human ferrochelatase was treated with 3-morpholinosydnonimine, a NO-generating compound, ferrochelatase activity decreased with disappearance of characteristic absorbance spectra of the iron-sulphur cluster. S-Nitroso-N-acetylpenicillamine also reduced the activity, in a dose-dependent manner. These results indicate that ferrochelatase activity can be modulated by NO synthesis probably through disruption of the iron-sulphur cluster. We propose that inactivation of ferrochelatase mediated by NO (or NO-derived species) may play a role in the regulation of haem metabolism.

Amino Acid Oxidoreductases↗
PubMed1995

Formation of 4,4'-methylene-bis(2-chloroaniline)-DNA adducts in yeast expressing recombinant cytochrome P450s.

N-Oxidation of 4,4'-methylene-bis(2-chloroaniline) (MBOCA) may lead to formation of DNA adducts. To determine if cytochrome P450s are involved in the formation of MBOCA derived-DNA adducts, yeast strains expressing rodent P450s were exposed to MBOCA, and 32P-postlabelling of nucleotides from yeast genomic DNA was done. Chromatographic analysis on PEI cellulose showed that, upon exposure to MBOCA for 1 h, nine DNA adducts were formed in yeast expressing phenobarbital-inducible rabbit P450 2B5. With a 4-h-exposure, all adducts increased in parallel. In cell-free experiments, the incubation of MBOCA with phenobarbital-induced rat microsomal fraction followed by incubation with thymus DNA, led to the formation of more than ten DNA adducts. When yeast expressing 3-methylcholanthrene-inducible rat P450 1A1 was exposed to MBOCA, one major and two minor adducts were formed. No adducts were detected in control yeast. These results show that recombinant rabbit P450 2B5 exhibits a potential activation of MBOCA and that rat P450 1A1 has some effect. The use of yeast expressing recombinant P450s and the technique of 32P-postlabelling facilitates a simple search for chemicals with carcinogenic potential.

Cytochrome P-450 Enzyme System↗
PubMed1995

Induction of terminal enzymes for heme biosynthesis during differentiation of mouse erythroleukemia cells.

To examine the induction of terminal enzymes of the heme-biosynthetic pathway during erythroid differentiation, mouse protoporphyrinogen oxidase (PPO) cDNA has been cloned. The deduced amino acid sequence derived from the nucleotide sequence revealed that mouse PPO consists of 477 amino acid residues, without the leader peptide, which is imported into mitochondria. Comparison of the amino terminus of the deduced amino acid sequence of mouse PPO cDNA with that of purified bovine PPO provided conclusive evidence for lack of the leader peptide in the former. The amino acid sequence has 86% and 28% identity with human PPO and Bacillus subtilis HemY, respectively. When mouse erythroleukemia (MEL) cells were induced with dimethylsulfoxide, PPO mRNA was induced within 12 h of treatment, and with further incubation, reached a plateau. mRNAs for coproporphyrinogen oxidase (CPO) and ferrochelatase (FEC) were induced within 12 h, and continued to increase with time up to 48 h. The activities of CPO and FEC markedly increased with time up to 72 h, while PPO activity increased 1.8-fold within 12 h and remained unchanged thereafter. Immunoblot analysis showed that levels of PPO, CPO and FEC paralleled their corresponding activities. The magnitude of PPO induction was less than that of CPO and FEC. Thus, induction of three terminal enzymes of the heme-biosynthetic pathway is an early event in MEL cell differentiation. The concomitant induction may play an important role in producing large amounts of heme during erythroid differentiation.

Amino Acid Sequence↗
PubMed1995

Androgen and oestrogen receptors in hepatocellular carcinoma and surrounding liver parenchyma: impact on intrahepatic recurrence after hepatic resection.

Seventy-eight patients in whom androgen or oestrogen receptors, or both, were assayed in hepatocellular carcinoma (HCC) and the surrounding liver were discharged from hospital after curative resection of the tumour. Intrahepatic recurrence was evaluated retrospectively after 28-128 months follow-up to determine the association with receptor status. Androgen and oestrogen receptors in HCC significantly influenced the intrahepatic recurrence rate. The recurrence-free 5-year survival rate was 55 per cent for patients who had androgen receptor-negative tumours, 24 per cent for oestrogen receptor-negative, 10 per cent for oestrogen receptor-positive and 0 for androgen receptor-positive (P = 0.0322). Recurrence-free 5-year survival in 57 patients who had both receptor assays was 75 per cent for patients who had androgen receptor-negative, oestrogen receptor-negative tumours, 50 per cent for androgen receptor-negative, oestrogen receptor-positive, but 0 for androgen receptor-positive, oestrogen receptor-positive and androgen receptor-positive, oestrogen receptor-negative (P = 0.0104). The presence or absence of androgen or oestrogen receptor in the liver, however, was not associated with intrahepatic recurrence (P = 0.7534). Thus, androgen receptors are strongly associated with intrahepatic recurrence of HCC, while oestrogen receptors are weakly associated. Receptor status in the normal liver was not related to intrahepatic recurrence.

Aged↗
PubMed1995

Effect of tauroursodeoxycholic acid on bile flow and calcium excretion in ischemia-reperfusion injury of rat livers.

BACKGROUND/AIMS: Tauroursodeoxycholic acid is known to have a hepatoprotective action in cholestatic disorders. We evaluated whether oral pretreatment with tauroursodeoxycholic acid could protect the liver from ischemia-reperfusion injury, with particular regard to its effect on bile flow and biliary calcium excretion. METHODS: A 1-hour in vivo ischemia-reperfusion model of 70% of the lobes of rat liver was used. Animals were divided into six groups (each group; n = 8); a non-ischemia sham group (CS), a control group without bile acids (CON), and 4 bile acid groups; 10 mg/kg and 50 mg/kg (U10, U50), taurocholic acid 10 mg/kg (CA10) and tauroursodeoxycholic acid 10 mg/kg (CD10). Bile acids were given orally for 7 days before operation. RESULTS: Three hours after reperfusion, oral bile acid pretreatment failed to reduce the hepatic ischemia-reperfusion injury biochemically, but histological improvement was observed in the tauroursodeoxycholic acid groups. After reperfusion, tauroursodeoxycholic acid significantly increased bile flow from the ischemic liver, and also significantly increased serum calcium concentration. Although tauroursodeoxycholic acid did not change biliary calcium concentration, it significantly enhanced total biliary calcium output during reperfusion. CONCLUSION: Thus, tauroursodeoxycholic acid inhibited tissue calcium accumulation and enhanced sinusoidal and biliary calcium output during hepatic ischemia-reperfusion. However, it is still unclear if calcium mobilization is part of the protective mechanisms of tauroursodeoxycholic acid in ischemia-reperfusion injury of the liver.

Analysis of Variance↗
PubMed1995

Rabphilin-3A binds to a M(r) 115,000 polypeptide in a phosphatidylserine- and Ca(2+)-dependent manner.

Rabphilin-3A is a putative target protein for Rab3A/Smg 25A, which is a member of the Ras-related small GTP-binding protein and implicated in neurotransmitter release from the synapse. Rabphilin-3A is composed of two functionally different domains: the N-terminal Rab3A-binding and the C-terminal phosphatidylserine- and Ca(2+)-binding domains. The C-terminal domain has two copies of an internal repeat that are homologous to the C2 domains of protein kinase C, synaptotagmin, and phospholipase A2 and C-gamma 1, which are known to bind phosphatidylserine and Ca2+. In this study, we attempted to identify the Rabphilin-3A-interacting molecule in bovine brain by use of an overlay assay technique. The 32P-labeled C-terminal fragment of Rabphilin-3A (281-704 amino acids) bound to a protein molecule with a M(r) of about 115 kDa which was immobilized on a nitrocellulose sheet. This protein was highly purified and characterized. The binding of the 32P-labeled C-terminal fragment to this protein was dependent on both phosphatidylserine and Ca2+, and inhibited by an excess amount of the C-terminal fragment and the C2 domain fragment (396-704 amino acids) but not by the N-terminal fragment (1-280 amino acids). These results indicate that Rabphilin-3A binds to a protein molecule with a M(r) of 115 kDa through the C2 domain in the presence of phosphatidylserine and Ca2+.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Beneficial effect of growth hormone on atherogenic risk in children with growth hormone deficiency.

We studied changes in the atherogenic index (total cholesterol divided by high-density lipoprotein cholesterol) in 12 prepubertal boys with growth hormone (GH) deficiency during 9 months of GH treatment. High-density lipoprotein cholesterol level increased until 5 months without significant changes in total cholesterol level; thus GH therapy may be beneficial in reducing the atherogenic index in boys with GH deficiency.

Adolescent↗
PubMed1995

Involvement of peripheral-type benzodiazepine receptors in the intracellular transport of heme and porphyrins.

To investigate the involvement of peripheral-type benzodiazepine receptors (PBR) in heme metabolism, we examined the interaction of [55Fe]heme with PBR. Transfection of the cloned mouse PBR-isoquinoline carboxamide-binding protein (PBR/IBP) cDNA into monkey kidney Cos-1 cells resulted in a 2.5-fold increase in [55Fe]hemin binding sites, concomitant with the increase in [3H]PK11195 binding sites, as compared with those seen in antisense PBR/IBP cDNA-transfected cells. The binding of hemin to the transfected receptors exhibited a relatively high affinity with a Kd of 12 nM, and was inhibited by several benzodiazepine ligands, including PK11195, Ro 5-4864, diazepam and protoporphyrin IX. When mouse liver mitochondria were incubated with [55Fe]hemin, the binding to PBR had a Kd of 15 +/- 1.8 nM. The Bmax of [55Fe]hemin binding to the mitochondria was 6.88 +/- 0.76 pmol/mg of protein, a value consistent with that of [3H]PK11195 binding, with a lower affinity. Coproporphyrinogen III, a precursor porphyrin produced in the cytosol, is translocated into mitochondria, then is converted to protoporphyrinogen IX; this conversion decreased in the presence of benzodiazepine ligands. To examine whether this decrease was related to a decrease in the binding of coproporphyrinogen to the mitochondria, the effects of benzodiazepines on the binding of coproporphyrinogen were examined. As the binding was dose-dependently inhibited by PK11195, Ro 5-4864, and diazepam, porphyrins are likely to be endogenous ligands for PBR. We propose that PBR play a role in the intracellular transport of porphyrins and heme.

Animals↗
PubMed1995

Clinical and enzymatic investigation of induction of oxygen free radicals by ischemia and reperfusion in human hepatocellular carcinoma and adjacent liver.

Serum concentration of thiobarbituric acid (TBA) reactants in the hepatic vein were measured before and after transient dearterialization of the liver in five human subjects bearing unresectable hepatocellular carcinoma (HCC). During 1 hour of the occlusion of the hepatic artery, change in TBA reactants level was slight. However, the mean value of TBA reactants in 1 hour after the reflow increased to 1.50 +/- 0.11 nmol/ml (mean +/- S.E.) and was significantly higher (p < 0.05) than those before hepatic dearterialization (1.28 +/- 0.11 nmol/ml) and just before the release of occlusion (1.32 +/- 0.09 nmol/ml). Further, two endogeneous scavenger enzymes, superoxide dismutase (SOD) and catalase (CAT), and one of the major sources of oxygen free radicals, xanthine oxidase (XOD) were measured in human untreated HCC and the corresponding adjacent liver tissue. The results demonstrated an increase in SOD in 81.8% (9/11) of HCC, and a decrease in CAT in 72.7% (8/11) of HCC when compared with the corresponding adjacent liver tissue. The mean value of SOD in HCC was significantly higher (66.8 +/- 6.5 vs 52.8 +/- 3.8 U/mg protein; p < 0.05), and that of CAT was significantly lower (22.6 +/- 2.4 vs 36.0 +/- 6.1 U/mg protein; p < 0.05) than those in liver tissue. All of nine HCC samples had a significantly lower activity of XOD (6.4 +/- 1.9 vs 20.3 +/- 3.4 pmol/minute/mg protein; p < 0.01) than the corresponding liver tissue. There was no obvious relation between the content of SOD and CAT in HCC, or in liver tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Repeated hepatic dearterialization for unresectable liver metastases from gastric cancer: review of five cases.

A novel method of repeated hepatic dearterialization was evaluated in five patients with multiple metastases from gastric cancer in both hepatic lobes. After gastrectomy with extensive lymph node dissection (R2/3), all patients underwent implantation of a vascular occluder around the hepatic artery. Cannulation of the hepatic artery was added for later chemotherapy. The hepatic artery was occluded repeatedly for 1 hour twice daily in combination with intrahepatic infusion of anticancer drugs for as long as possible. Three of five patients demonstrated marked tumour regression with unexpectedly long survival (16 months in two patients and one still alive at 15 months). Carcinoembryonic antigen (CEA) levels decreased to almost normal in four patients who had initially high levels. The present experiences seems to indicate that long survival can be hoped for in patients with advanced gastric cancer with unresectable liver metastases.

Aged↗
PubMed1995

Tentorial meningioma and painful tic convulsif. Case report.

A case is presented of painful tic convulsif caused by a posterior fossa meningioma, with right trigeminal neuralgia and ipsilateral hemifacial spasm. Magnetic resonance images showed an ectatic right vertebral artery as a signal-void area in the right cerebellopontine angle. At operation the tentorial meningioma, which did not compress either the fifth or the seventh cranial nerves directly, was totally removed via a suboccipital craniectomy. The patient had complete postoperative relief from the trigeminal neuralgia and her hemifacial spasm improved markedly with decreased frequency. From a pathophysiological standpoint, the painful tic convulsif in this case was probably produced by the tumor compressing and displacing the brainstem directly, with secondary neurovascular compression of the fifth and seventh nerves (the so-called "remote effect").

Aged↗
PubMed1995

[Immunohistochemical analysis of adhesion molecules in directional coronary atherectomy specimens].

Chronic inflammatory cells are key components in the progression of atherosclerotic plaques and restenosis after coronary angioplasty. Adhesion molecules are fundamental in inflammatory processes. Therefore, the distributions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM) were investigated in directional coronary atherectomy specimens obtained from 14 patients, in 6 with acute coronary syndromes (myocardial infarction and unstable angina within 1 month), 6 with old myocardial infarction and 2 with stable effort angina. There were eight primary lesions and six restenotic lesions. Atherectomy tissue fragments were snap frozen and cut into 4 microns thick cryostat sections for immunohistochemical staining by avidin-biotin complex immunoperoxidase techniques using adhesion molecule specific monoclonal antibodies BBIG-I1 (ICAM-1) and BBIG-V1 (VCAM). The cells of lesions were characterized in sequential sections by macrophage marker KP1 (CD68), endothelial marker JC/70A (CD31), and smooth muscle cell marker 1A4 (alpha-smooth muscle actin). Four restenotic lesions that had undergone a prior balloon angioplasty within a few months consisted of intimal proliferation and the other lesions were atherosclerotic plaque. Macrophage-rich areas were seen in the lesions from acute coronary syndromes and/or early restenotic lesions. Expression of ICAM-1 or VCAM was strongly associated with macrophage-rich areas, but VCAM staining was weaker than ICAM-1 except in one restenotic lesion. Macrophages that express ICAM-1 and/or VCAM may be important in the unstable plaques and restenotic lesions related to disease activity of ischemic heart disease.

Aged↗
PubMed1995

[A randomized crossover comparison of azasetron and granisetron in the prophylaxis of emesis induced by chemotherapy including cisplatin].

The clinical application of 5-HT3 receptor antagonists has enabled continuation of the course of chemotherapy including cisplatin, which induces strong nausea and vomiting, and to prevent the delay of curative treatment for cancer patients receiving neoadjuvant chemotherapy. However, with the development of basic research on the mechanisms of vomiting, each 5-HT3 receptor antagonist has appeared to have different pharmacological actions and, subsequently, the difference in the clinical efficacy of each drug has been reported in Europe and USA. In freshly advanced head and neck carcinoma cases, a randomised crossover study was performed to compare the efficacy and safety profile of a single intravenous dose for 7 days of azasetron (10 mg/day) or granisetron (3 mg/day) in the prophylaxis of nausea and vomiting induced by multi-drug chemotherapy including cisplatin (50 mg/m2 or 60 mg/m2). Anti-emetic effects were evaluated by the protective rates for nausea and vomiting for 7 days following the start of cisplatin administration. Both 5-HT3 receptor antagonists were highly effective in the prophylaxis of acute and delayed emesis induced by chemotherapy, whereas the efficacies of azasetron on day 3 and 4 were superior to those of granisetron. No adverse effect of either drug was observed in this study.

Aged↗
PubMed1995

[Efficacy of repeated hepatic dearterialization combined with intra-arterial infusion chemotherapy for unresectable tumors of the liver].

In the present study, repeated hepatic dearterialization combined with intra-arterial infusion chemotherapy was performed in patients with unresectable tumors of the liver. Of 36 patients, 16 had primary liver tumors (13 hepatocellular carcinomas and 3 cholangiocellular carcinomas), while 20 had metastatic tumors (7 gastric carcinomas, 10 colon carcinomas, 2 pancreatic carcinomas, and 1 gastric carcinoid). A significantly better survival outcome was found in those with intra-arterial infusion chemotherapy and those without cirrhosis. In the HCC cases, those with the therapy tended to show a better survival as compared with the natural history. Remarkable tumor regression was found in four (67%) of six patients with metastases of gastric cancer.

Aged↗
PubMed1995

Cirrhotic livers can tolerate 30 minutes ischaemia at normal environmental temperature.

OBJECTIVE: To find out the safe time limit for Pringle's manoeuvre (compression of the hepatic artery and portal vein in the gastrohepatic omentum to halt bleeding) under normal environmental conditions for limited resection of cirrhotic livers. DESIGN: Prospective open study. SETTING: University hospital, Japan. SUBJECTS: Pringle's manoeuvre was used in 73 consecutive patients with hepatocellular carcinoma and cirrhosis (Child's classification: A = 44, B = 24, and C = 5), and in 20 patients it was not used (Child's classification: A = 11, B = 5, and C = 4). INTERVENTIONS: Limited hepatic resections were done with the duration of Pringle's manoeuvre ranging from 5 to 41 minutes. 15 patients simultaneously underwent 17 other abdominal operations. MAIN OUTCOME MEASURES: Child's classification, blood loss during operation, and duration of hepatic ischaemia. RESULTS: The morbidity and mortality with Pringle's manoeuvre were 1 (2%) and 0 in Child's A cirrhosis, 7 (29%) and 2 (8%) in Child's B cirrhosis, and 2 (40%) and 1 (20%) in Child's C cirrhosis. The higher rates in class B and C patients were ascribed to the amount of blood loss rather than to Pringle's manoeuvre. CONCLUSION: Pringle's manoeuvre can be used safely for up to 30 minutes during limited resection of the cirrhotic liver.

Adult↗