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Biomedical subjects

N Shimada

Publications and source records attributed to N Shimada.

At least 127 records · Page 7Linked to original sources
PubMed1998

A comparative study of nucleolar organizer region, proliferating cell nuclear antigen and epidermal growth factor receptor staining in colon tumours.

Several studies have reported that proliferating cell nuclear antigen (PCNA), nucleolar organizer regions (NOR) and epidermal growth factor receptor (EGF-R) are cellular proliferation parameters in malignant tumours. However, the correlation of EGF-R with PCNA and NOR has not been reported in colon tumours. To clarify this, we investigated the correlation of the expression of EGF-R with PCNA and NOR in colonic epithelial tumours. Using immunohistochemical staining and one-step silver staining techniques, the expressions of EGF-R-, PCNA- and NOR-associated protein were studied in paraffin sections from five normal mucosae, 10 adenomas with mild atypia, 16 adenomas with moderate atypia, 32 adenomas with severe atypia including carcinoma in situ and 47 with invasive colon carcinomas. Significant differences were found among the respective degrees of atypia in Ag-NOR counts, PCNA labelling index (LI), and the expression of EGF-R. However, there were no significant differences among the Ag-NOR counts of the severe atypia and invasive carcinoma. There was a significant positive correlation between Ag-NOR counts and PCNA LI (P < 0.001). The Ag-NOR counts and PCNA LI in EGF-R-positive cases were higher than in EGF-R-negative cases (P < 0.001). These results indicate that each of the parameters increased significantly with the increase in atypia and the progression of cancer. Epidermal growth factor receptor provokes an exacerbation of protein synthesis and the cell cycle in colonic epithelial tumours.

Adenoma↗
PubMed1998

[Detection of Streptococcus pneumoniae in clinical specimens, its antimicrobial susceptibility and serotypes].

The purpose of our investigation was the detection of S. pneumoniae and the isolation frequency of PRSP/PISP from the patients of the area. 457 strains of S. pneumoniae were isolated from the clinical specimens which had been requested for cultivation from the individual general practitioners in the city. Screening of the PRSP/PISP in 457 strains was carried out with the oxacillin (MPIPC) disk method. The MIC (benezylpenicillin: PCG) was measured at the same time in 73 strains, and compared with the disk method. The results were as follows: 1) Regarding the detection rate of S. pneumoniae, nose discharge was the highest (11.4%) in all the specimens. 2) There was a greater number of isolation of S. pneumoniae in one year from November to March. Then it was scarce in August and September. This change in seasons was noted. 3) There were many 9-year olds and over-60 year olds in the age group of the patients in whom the S. pneumoniae was isolated. 4) All 30 strains where a 6 mm diameter was found when a MIC was compared with the MPIPC disk method were resistant (PRSP/PISP). All 20 strains with a > or = 20 mm diameter were sensitive (PSSP). But in the 23 strains which had a 7 mm -19 mm, 7 strains (30%) were PSSP, and 16 strains (70%) in the intermediate (PISP). 5) A diameter of 6 mm was found in 194 strains (42.5%) with the MPIPC disk method, among the 457 strains isolated from the clinical specimens. 141 strains (30.9%) were found with a diameter of 7 mm -19 mm and 122 strains (26.7%) with a diameter of > or = 20 mm. 6) More than 70% in PRSP/PISP were multiple antimicrobiotics resistant strains to PCG, EM and MINO. 7) The distribution of the serotype in PRSP/PISP was in the order of 19 type (41.3%), 23 type (21.7%), 6 type (13.0%). Moreover, it was in the order of 3 type (18.5%), 6 type (11.1%), 19 type (11.1%), and there were few 23 type (3.7%) for PSSP. The distribution of the serotype was different for PRSP/PISP and PSSP.

Adolescent↗
PubMed1998

Metalloproteinase-9 mRNA expression in monocytes from patients with chronic renal failure.

Long-term dialysis patients suffer from various complications including atherosclerosis. It has been suggested that metalloproteinases (MMPs) contribute to vascular remodeling during the development and progression of human atherosclerosis. Activated human monocytes have been demonstrated to secrete MMPs. In the present study, we measured levels of MMP mRNA in peripheral blood monocytes obtained from patients on continuous ambulatory peritoneal dialysis (CAPD) or hemodialysis (HD) and chronic-renal-failure patients not undergoing dialysis. Twenty patients with chronic renal failure were not undergoing dialysis, 20 patients were on CAPD, 40 patients were on chronic HD and 20 healthy volunteers served as controls. We used cDNA probes encoding for MMP-1, MMP-2, MMP-3 and MMP-9 and glyceraldehyde phosphate dehydrogenase. Higher levels of MMP-9 mRNA in the peripheral blood monocytes were observed in HD patients than in CAPD patients, undialyzed chronic renal failure patients or healthy controls. MMP-9 mRNA levels at the end of HD were not significantly higher than those at the start of HD. MMP-9 mRNA levels from HD patients did not differ among the types of membranes. We could detect minimal MMP-1, MMP-2 and MMP-3 mRNA expression in monocytes from all groups. Serum gelatinase activity was detectable in all samples; however, no significant differences existed among the groups. In summary, MMP-9 mRNA expression is enhanced in monocytes from HD and CAPD patients, and the enhancement may be, in part, associated with cardiovascular complications, including atherosclerosis, in dialysis patients. This increase in monocyte MMP-9 mRNA levels is lower in CAPD patients that it is in HD patients.

Adult↗
PubMed1998

Hemoperfusion with polymyxin B-immobilized fiber attenuates the increased plasma levels of thrombomodulin and von Willebrand factor from patients with septic shock.

AIMS: The present study assessed whether plasma levels of thrombomodulin and von Willebrand factor (vWF) are altered in patients with septic shock and whether treatment with polymyxin B-immobilized fiber (PMX-F) affects these levels. METHODS: Twenty-four patients with septic shock and 20 normal healthy controls were included in this study. Plasma levels of thrombomodulin and vWF were measured by enzyme immunoassay (EIA). The treatments with direct hemoperfusion using PMX-F column on patients with septic shock were repeated twice for 2 h each. Healthy controls were not subjected to hemoperfusion. RESULTS: 13 of 24 patients with septic shock survived (survival rate was 54.2%). Levels of blood endotoxin decreased significantly from 41.2 +/- 4.8 pg/ml at baseline to 13.2 +/- 3.6 pg/ml after direct hemoperfusion. Systolic blood pressure increased significantly from 82 +/- 6 mm Hg at baseline to 118 +/- 12 mm Hg after treatment. The patients with septic shock demonstrated significantly increased plasma levels of thrombomodulin (p < 0.001) and vWF (p < 0.001) compared with those in healthy controls. These increased levels of plasma thrombomodulin and vWF in patients with septic shock decreased significantly after treatment with PMX-F (p < 0.01). CONCLUSION: These data suggest that plasma thrombomodulin and vWF may be related to septic shock and that PMX-F is effective in reducing these factors in patients with septic shock.

Adult↗
PubMed1998

Glioblastoma following radiotherapy in a patient with tuberous sclerosis.

A 26-year-old male with tuberous sclerosis developed a glioblastoma in the right temporal lobe 8 years after surgical excision and irradiation of a subependymal giant cell astrocytoma. The glioblastoma was probably an irradiation-induced tumor. Irradiation should not be given routinely for subependymal giant cell astrocytoma.

Adult↗
PubMed1998

Oxidation of histamine H1 antagonist mequitazine is catalyzed by cytochrome P450 2D6 in human liver microsomes.

Mequitazine [10-(3-quinuclidinylmethyl) phenothiazine] is a long-acting and selective histamine H1-receptor antagonist that is mainly biotransformed by human liver microsomes to yield hydroxylated and S-oxidized metabolites. Mequitazine hydroxylase was inhibited by propranolol and quinidine. Lineweaver-Burk plots for the hydroxylation and the S-oxidation indicated that the hydroxylation occurred with a low Km (0.72 +/- .26 microM) in human liver microsomes. Microsomes from genetically engineered human B-lymphoblastoid cells expressing cytochrome P450 2D6 (CYP2D6) efficiently metabolized mequitazine to the hydroxylated and S-oxidized metabolites. The results indicate that CYP2D6 isozyme is a major form of CYP responsible for the metabolism of mequitazine in human liver microsomes. Inhibition of CYP3A-catalyzed midazolam 1'-hydroxylase by various histamine H1 antagonists, including mequitazine, suggested that mequitazine and some other histamine H1 antagonists could also be inhibitors of CYP3A in human liver microsomes.

1-Propanol↗
PubMed1998

Cytochrome P450 2C9 catalyzes indomethacin O-demethylation in human liver microsomes.

Indomethacin is a widely used nonsteroidal anti-inflammatory drug. We studied the human cytochrome P450 (CYP) isoform responsible for indomethacin O-demethylation, the major metabolic pathway for indomethacin. For indomethacin O-demethylase activities, the KM value was 34.6 +/- 5.4 muM and the Vmax value was 14.1 +/- 3.9 pmol/mg/min in human liver microsomes (N = 4). Indomethacin O-demethylase activity in human liver microsomes was competitively inhibited by sulfaphenazole, (S)-warfarin, and tolbutamide and was not affected by alpha-naphthoflavone, (S)-mephenytoin, or erythromycin. Indomethacin O-demethylase activities in microsomes from nine human livers were significantly correlated with tolbutamide hydroxylase activities (r = 0.750, p < 0.05) and not with (S)-mephenytoin 4'-hydroxylase activities. When the capacity for indomethacin O-demethylation in microsomes of B lymphoblastoid cells expressing human CYPs was investigated at an indomethacin concentration of 5 microM, cDNA-expressed CYP2C9 exhibited 6-fold greater activity than did CYP2C19. At an indomethacin concentration of 50 microM, cDNA-expressed CYP1A2 and CYP2D6 also exhibited slight activities. The KM values were 9.9 +/- 1.2 and 117.1 +/- 13.8 microM and the Vmax values were 0.33 +/- 0.05 and 0.24 +/- 0.04 pmol/min/pmol CYP in microsomes with cDNA-expressed CYP2C9 and CYP2C19, respectively (N = 4). Considering the 16-fold higher intrinsic clearance of CYP2C9, compared with that of CYP2C19, and these expression levels in human livers, the contribution of CYP2C19 to indomethacin O-demethylation was considered to be negligible. Indomethacin appears to be O-demethylated exclusively by CYP2C9 in humans.

Alkylation↗
PubMed1998

Human buprenorphine N-dealkylation is catalyzed by cytochrome P450 3A4.

Buprenorphine (BN) is a thebaine derivative with analgesic properties. To identify and characterize the cytochrome P450 (CYP) enzyme(s) involved in BN N-dealkylation, in vitro studies using human liver microsomes and recombinant human CYP enzymes were performed. Norbuprenorphine formation from BN was measured by a simple HPLC-UV assay method, without extraction. The BN N-dealkylation activities in 10 human liver microsomal preparations were strongly correlated with microsomal CYP3A-specific metabolic reactions, i.e. triazolam 1'-hydroxylation (r = 0.954), midazolam 1'-hydroxylation (r = 0.928), and testosterone 6beta-hydroxylation (r = 0.897). Among the eight recombinant CYP enzymes studied (CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4), only CYP3A4 could catalyze BN N-dealkylation. The apparent KM value for recombinant CYP3A4 was similar to that for human liver microsomes (23.7 vs. 39.3 +/- 9.2 microM). The demonstration of BN N-dealkylation by recombinant CYP3A4 and the agreement in the affinities (apparent KM values) of human liver microsomes and recombinant CYP3A4 provide the most supportive evidence for BN N-dealkylation being catalyzed by CYP3A4.

Alkylation↗
PubMed1997

Multiple transcripts for rat nucleoside diphosphate kinase alpha isoform are structurally categorized into two groups that exhibit cell-specific expression and distinct translation potential.

Rat nucleoside diphosphate (NDP) kinase is composed of two isoforms (alpha and beta) encoded by independent genes. The mRNAs are expressed ubiquitously; however, the level of expression is tissue-dependent and is also up- or down-regulated under certain conditions, including growth stimulation, differentiation, and tumor metastasis. To address the regulatory mechanisms of gene expression for the rat NDP kinase major isoform alpha (an nm23-H2/PuF homologue), we identified the transcription initiation sites in detail by RNase protection and 5'-rapid amplification of DNA ends and located the core promoter region by chloramphenicol acetyltransferase assay. The transcripts, initiated from an extraordinarily wide range of sites, were categorized into two groups; one transcribed from an upstream region was spliced in the untranslated region (group 1), whereas the other initiated in the downstream region was not (group 2). RNase protection demonstrated that the group 1 mRNA was the dominant form present in all tissues except heart and skeletal muscle. In situ hybridization revealed cell-specific expression of these mRNA species. Furthermore, they differed in the translational efficiency (the group 2 alpha > beta > the group 1 alpha). These findings suggest that the regulation of the NDP kinase expression at both transcriptional and posttranscriptional steps could be fundamentally governed by the selection of transcription initiation sites.

Animals↗
PubMed1997

Association between frequency of amino acid changes in core region of hepatitis B virus (HBV) and the presence of precore mutation in Japanese HBV carriers.

To elucidate the relationship between the frequency of core mutations and precore mutation of hepatitis B virus (HBV) in Japanese HBV carriers, we investigated the nucleotide sequence of the precore/core region of HBV in 26 Japanese HBV carriers [15 who were HBe antigen-negative (HBeAg-) and 11 who were HBeAg-positive (HBeAg+)]. The number of amino acid changes (5.9 +/- 3.8) in the core region of HBV in HBeAg-carriers was significantly greater than that in the HBeAg+ carriers (1.5 +/- 1.0; P < 0.005). The precore stop codon mutation was found in 93.3% of HBeAg-negative HBV carriers, while no precore mutation was found in the HBeAg-positive HBV carriers, suggesting that the frequency of core mutations may be associated with the presence of the precore stop codon mutation. However, there was no significant difference in the frequency of amino acid changes among HBeAg-HBV carriers. The mean number of core amino acid changes of liver cirrhosis patients, chronic active hepatitis patients, chronic persistent hepatitis patients, and asymptomatic carriers were 2.7 +/- 1.5, 6.0 +/- 2.2, 4.7 +/- 1.2, and 8.4 +/- 5.3, respectively. We detected hot spots for core mutations, which showed characteristic localizations and specific substitutions: Gly-87, Leu-97, and Thr-130 were detected exclusively in patients with chronic liver disease with or without HBeAg. To address further the relationship between frequency of core mutations and the presence of the precore stop codon mutation, we investigated the precore/core nucleotide sequence serially along with seroconversion in three patients with chronic hepatitis B in whom the hepatitis either became inactive or remained active after the seroconversion. Emergence of the precore stop codon mutation and a significant increase in core amino-acid changes after seroconversion were noted in all three patients. Our results suggest a close association between the frequency of core amino acid changes and the presence of the precore stop codon mutation; some characteristic core mutations may be associated with the clinical course of chronic hepatitis B in Japanese patients.

Adult↗
PubMed1997

Prediction of in vivo drug metabolism in the human liver from in vitro metabolism data.

As a new approach to predicting in vivo drug metabolism in humans, scaling of in vivo metabolic clearance from in vitro data obtained using human liver microsomes or hepatocytes is described in this review, based on the large number of literature data. Successful predictions were obtained for verapamil, loxtidine (lavoltidine), diazepam, lidocaine, phenacetin and some other compounds where CLint,in vitro is comparable with CLint,in vivo. On the other hand, for some metabolic reactions, differences in CLint,in vitro and CLint,in vivo greater than 5-fold were observed. The following factors are considered to be the cause of the differences: (1) metabolism in tissues other than liver, (2) incorrect assumption of rapid equilibrium of drugs between blood and hepatocytes, (3) presence of active transport through the sinusoidal membrane, and (4) interindividual variability. Furthermore, the possibility of predicting in vivo drug metabolic clearance from results obtained using a recombinant system of human P450 isozyme was described for a model compound, YM796, where the predicted metabolic clearances obtained from the recombinant system, taking account of the content of the P450 isozyme CYP3A4 in the human microsomes, were comparable with the observed clearances using human liver microsomes containing different amounts of CYP3A4. Even in the case where the first-pass metabolism exhibits nonlinearity, it appears to be possible to predict in vivo metabolic clearance from in vitro metabolic data.

Biological Transport, Active↗
PubMed1997

Potential sensitivity of hepatic specific protein regucalcin as a marker of chronic liver injury.

A novel calcium-binding protein regucalcin has been shown to be specifically expressed in the liver of various specifies including human. Regucalcin concentration in the serum of patients with chronic liver injury was estimated by enzyme-linked immunoadsorbent assay (ELISA) with rabbit-anti-regucalcin IgG. Serum samples were obtained from 42 persons who were diagnosed as liver disorder. Serum regucalcin concentration in all patients was in the range of 3.7-69.6 ng/ml, although regucalcin was not entirely seen in the serum of normal subjects (10 persons) without hepatitis. Meanwhile, in 18 patients with liver injury, serum glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities were normal value (less than 40 I.U./I). Serum GOT and GPT activities from 24 patients showed a comparatively higher level (50-234 I.U./I). The present results demonstrate the potential sensitivity of regucalcin as a marker of chronic liver injury.

Alanine Transaminase↗
PubMed1997

Relation between obesity in young adulthood and risk of non-insulin-dependent diabetes mellitus.

OBJECTIVE: To investigate the independent effect of obesity in young adulthood on the risk of non-insulin-dependent diabetes mellitus (NIDDM). DESIGN: Retrospective cohort design. SUBJECTS: One-thousand, one hundred and five Japanese male railway employees aged 30 y or older who received a health examination from February to May 1995. MEASUREMENTS: Adjusted odds ratios (ORs) for subsequent NIDDM determined by the WHO criteria or a physician's diagnosis, among men who were obese at ages 20, 25, or 30 y. RESULTS: Men who were obese (BMI > or = 25.0 kg/m2) at ages 25 or 30 y had significantly positive ORs for NIDDM after adjustment for age and maximum BMI (8.20 and 3.94, respectively). Men in the top quintile of BMI at any age also had significantly positive ORs for NIDDM (2.13, 7.92, and 3.49, at 20, 25, and 30 y, respectively). After mutual adjustment for BMI at age 20, 25 and 30 y, only obesity at age 25 y demonstrated a significantly positive OR for NIDDM in both absolute and relative models (6.98 for BMI > or = 25.0 and 9.99 for the top quintile, respectively). CONCLUSION: Men who were obese (BMI > or = 25.0 kg/m2 or top quintile) at age 25 y were at significantly high risk of prevalent NIDDM in subsequent years, independent of age, maximum BMI, and BMIs at age 20 and 30 y.

Adult↗
PubMed1997

Relationship between weight change in young adulthood and the risk of NIDDM. The Sotetsu Study.

OBJECTIVE: To investigate the independent effect of weight change in young adulthood on the risk of prevalent NIDDM among middle-aged Japanese men. RESEARCH DESIGN AND METHODS: A case-control study was carried out in 895 male employees aged > or = 30 years of a railway company located in the vicinity of Tokyo. Adjusted odds ratios (ORs) were calculated for prevalent diabetes in each category of weight change (obtained from subjects' medical records) in young adulthood and adulthood. Adjustment for current age, initial BMI, and weight change in each age stratum was performed by the Mantel-Haenszel method or multiple logistic regression analysis. RESULTS: Weight change between 20 years of age and the age at maximum weight was not associated with the risk of NIDDM. Weight gain between 20 and 25 years of age was significantly and positively associated with the risk of NIDDM (OR 3.87 for gains > or = 10.0 kg, 2.53 for gains of 5.0-9.9%, and 3.73 for gains > or = 10.0%). On the other hand, moderate weight gain after 30 years of age was significantly inversely associated with NIDDM (OR 0.44 for gains of 5.0-9.9 kg, 0.15 for gains of 10.0-19.9%, and 0.38 for gains of 20.0-29.9%). CONCLUSIONS: Extreme weight gain between 20 and 25 years of age is a significant predictor of NIDDM, independent of current age, BMI at 20 years of age, and weight change within other age strata.

Adult↗
PubMed1997

Identification of cytochrome P450 isoforms involved in citalopram N-demethylation by human liver microsomes.

Studies to assess the enzyme kinetic behavior and to identify the cytochrome P450 (CYP) isoform(s) involved in the major metabolic pathway (N-demethylation) for citalopram (CIT), a selective serotonin reuptake inhibitor, were performed using human liver microsomes and cDNA-expressed human cytochrome P450 isoforms. The N-demethylation activities showed significant correlations with the alpha- and 4-hydroxylation activities of triazolam (r(s) = 0.818 and 0.851, respectively; P < .01) in 10 different human liver microsomes. Anti-CYP3A antibodies and ketoconazole strongly inhibited CIT N-demethylation. In addition, there was a significant correlation between CIT N-demethylation and (S)-mephenytoin 4'-hydroxylation (r(s) = 0.773, P < .05), although little inhibition was observed in the presence of anti-CYP2C antibodies or (S)-mephenytoin. cDNA-expressed CYP3A4 and CYP2C19 catalyzed CIT N-demethylation, whereas no appreciable activities were observed for CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6 and CYP2E1. The percentage contributions of CYP3A4 and CYP2C19 to the overall N-demethylation of CIT in human liver microsomes were estimated using a relative activity factor; respective values of 70% and 7% were calculated for microsomes obtained from livers from putative extensive metabolizers for (S)-mephenytoin 4'-hydroxylation. These results suggest that CYP3A4 is the major isoenzyme and CYP2C19 is the minor form involved in the major metabolic pathway for CIT in human liver microsomes.

Aryl Hydrocarbon Hydroxylases↗