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T Kuroki

Publications and source records attributed to T Kuroki.

At least 91 records · Page 5Linked to original sources
PubMed1999

ROCK inhibitor Y-27632 attenuates stellate cell contraction and portal pressure increase induced by endothelin-1.

By using a selective ROCK inhibitor Y-27632, the role of Rho-ROCK signaling in the function of hepatic stellate cells in culture was studied. Stellate cells maintained the "star-like" configuration of the quiescent stage in the presence of Y-27632, while the expression of smooth muscle alpha-actin and PDGF receptor beta was not affected by the agent. Serum-stimulated migration of the cells was significantly suppressed by Y-27632. The contraction of stellate cells induced by 5 nM endothelin-1 was attenuated by the agent in a dose-dependent manner. Formation of F-actin stress fibers and phosphorylation of myosin light chain was apparently reduced by Y-27632 even under the stimulation with endothelin-1. On the other hand, ex vivo liver perfusion experiment revealed that endothelin-1 (2 nM)-induced increase of portal vein constriction was almost completely inhibited by 20 microM Y-27632 with a concomitant improvement of hepatocyte degeneration. These results suggest that ROCK is one of the key regulators of stellate cell motility and that the clinical application of ROCK inhibitors such as Y-27632 should be considered in the reduction of portal hypertension in liver fibrosis and cirrhosis.

Actins↗
PubMed1999

Effects of atypical antipsychotic drugs vs. haloperidol on expression of heat shock protein in the discrete brain regions of phencyclidine-treated rats.

Haloperidol augmented a trend of an increase in the heat shock protein (hsp70) mRNA levels induced by phencyclidine (PCP) in rat medial prefrontal cortex, nucleus accumbens and striatum, while the atypical antipsychotic drugs such as clozapine, olanzapine and risperidone decreased it. When administered alone, clozapine, but not haloperidol, decreased hsp70 mRNA levels. Haloperidol and the atypical antipsychotic drugs may thus have differential effects on hsp70 expression in some brain regions of PCP-treated rats.

Animals↗
PubMed1999

Frequent mutation of beta-catenin and APC genes in primary colorectal tumors from patients with hereditary nonpolyposis colorectal cancer.

Hereditary nonpolyposis colorectal cancer (HNPCC) is characterized by defective DNA mismatch repair, which results in genetic instability of tumors; however, only a few target genes have been recognized. Our previous study detected a low frequency of APC gene mutation (21%) in colorectal tumors from HNPCC patients, in contrast to a high frequency of APC gene alteration (>70%) in non-HNPCC tumors. Because both beta-catenin and ACP gene mutations have recently been shown to activate the same signaling pathway, we analyzed beta-catenin mutation in HNPCC tumors. A notable frequency of beta-catenin gene mutation (43%, 12 of 28) was found to occur in HNPCC colorectal tumors. Beta-catenin mutations were not detected in tumors with APC mutations. All beta-catenin mutations detected in HNPCC tumors existed within the regulatory domain of beta-catenin. Immunohistochemical staining of tumors with this mutation showed accumulation of beta-catenin protein in nuclei. These and previous data from our laboratory suggest that activation of the beta-catenin-Tcf signaling pathway, through either beta-catenin or APC mutation, contributes to HNPCC colorectal carcinogenesis in approximately 65% of cases.

Base Pair Mismatch↗
PubMed1999

Interferon therapy reduces the risk for hepatocellular carcinoma: national surveillance program of cirrhotic and noncirrhotic patients with chronic hepatitis C in Japan. IHIT Study Group. Inhibition of Hepatocarcinogenesis by Interferon Therapy.

BACKGROUND: Previous studies on the effect of interferon therapy on the incidence of hepatocellular carcinoma have not sufficiently assessed degree of liver fibrosis, a major risk factor for hepatocellular carcinoma. OBJECTIVE: To evaluate the effect of interferon therapy on incidence of hepatocellular carcinoma, adjusting for risk factors, including the degree of liver fibrosis. DESIGN: Retrospective cohort study. SETTING: Seven university hospitals and one regional core hospital in Japan. PATIENTS: 2890 patients with chronic hepatitis C who had undergone liver biopsy since 1986. Of these patients, 2400 received interferon and 490 were untreated. MEASUREMENTS: The degree of liver fibrosis was assessed from stage F0 (no fibrosis) to stage F4 (cirrhosis). Response to interferon was determined virologically and biochemically. Screening for development of hepatocellular carcinoma was performed periodically during an average follow-up of 4.3 years. Effect of interferon therapy on the risk for hepatocellular carcinoma was analyzed by using Cox proportional hazards regression. RESULTS: Hepatocellular carcinoma developed in 89 interferon-treated patients and in 59 untreated patients. Among untreated patients, the annual incidence of hepatocellular carcinoma increased with the degree of liver fibrosis, from 0.5% among patients with stage F0 or F1 fibrosis to 7.9% among patients with stage F4 fibrosis. The cumulative incidence in treated and untreated patients differed significantly for patients with stage F2 fibrosis (P = 0.0128) and for those with stage F3 fibrosis (P = 0.0011). In multivariate analysis, interferon therapy was associated with a reduced risk for hepatocellular carcinoma (adjusted risk ratio, 0.516 [95% CI, 0.358 to 0.742]; P < 0.001), especially among patients with sustained virologic response (risk ratio, 0.197 [CI, 0.099 to 0.392]), among those with persistently normal serum alanine aminotransferase levels (risk ratio, 0.197 [CI, 0.104 to 0.375]), and among those with alanine aminotransferase levels less than two times the upper limit of normal (risk ratio, 0.358 [CI, 0.206 to 0.622]). CONCLUSIONS: Interferon therapy significantly reducesthe risk for hepatocellular carcinoma, especially among virologic or biochemical responders.

Alanine Transaminase↗
PubMed1999

Hepatitis C virus core protein regulates cell growth and signal transduction pathway transmitting growth stimuli.

To investigate the transforming potential of hepatitis C virus (HCV), HCV core protein was produced in BALB/3T3 A31-I-1 cells. The cells expressing HCV core gene cooperatively with the v-H-ras gene showed loss of contact inhibition, morphological alterations, and anchorage-independent and serum-independent growth. The cells producing HCV core protein showed enhanced growth against stimulus of growth factor. In addition, antisense oligodeoxynucleotides against mRNA encoding HCV core protein suppressed the growth of HCV core-producing cells. Furthermore, HCV core protein activated mitogen-activated protein kinase and serum response element, which respond to growth stimuli. From these results, we concluded that HCV core protein is involved in the acquisition of cell growth advantage.

3T3 Cells↗
PubMed1999

Higher frequency of Smad4 gene mutation in human colorectal cancer with distant metastasis.

We have previously detected an increased frequency of loss of heterozygosity (LOH) on chromosome 18q during progression of colorectal carcinomas. To clarify the target of 18qLOH, mutation of Smad4 and Smad2 genes was analysed in 176 colorectal tumors with different stages, including liver metastasis, from 111 sporadic, 52 familial adenomatous polyposis (FAP) and nine hereditary nonpolyposis colorectal cancer (HNPCC) patients. Mutation of other Smad gene families in the TGF-beta signaling pathway was also examined. Twenty-one Smad4 mutations and one Smad2 mutation were detected, whereas mutation of Smad3, 6 and 7 genes was not detected. Smad4 mutations included seven frameshift, one inframe deletion, four nonsense and nine missense mutations, 95% of which resulted in alteration of Smad4 protein regions included in homo-oligomer and hetero-oligomer formation. Frequencies of tumors with Smad4 mutation were 0/40 (0%) in adenoma, 4/39 (10%) in intramucosal carcinoma, 3/44 (7%) in primary invasive carcinoma without distant metastasis, 6/17 (35%) in primary invasive carcinoma with distant metastasis, and 11/36 (31%) in distant metastasis (metastatic/non-metastatic: P=0.006 approximately 0.01). Loss of the other allele was observed in 19 of 20 (95%) invasive and metastasized carcinomas with Smad4 mutations. In four cases both primary and metastasized carcinomas in the same patients showed the same mutations. The present results suggest that Smad4 gene is one of true targets of 18qLOH, and that its inactivation is involved in advanced stages, such as distant metastasis, in human colorectal carcinogenesis.

Colorectal Neoplasms↗
PubMed1999

Mouse Sprr2 genes: a clustered family of genes showing differential expression in epithelial tissues.

Small proline-rich (SPR) proteins are structural components of the cornified cell envelope of stratified squamous epithelia. They are subdivided into three families, i.e., SPR1, SPR2, and SPR3, of which the SPR2 family is the most complex. To understand the significance of this complexity, we have isolated 11 mouse Sprr2 genes, constructed a provisional physical map of the Sprr2 locus on mouse Chromosome 3, and examined the expression patterns of the Sprr2 genes in mouse epithelial tissues. The 11 Sprr2 sequences are highly conserved with a central domain containing a variable number of repeats. In situ hybridization showed the Sprr2 expression to be confined to epithelia. RT-PCR using primers specific for each of the 11 Sprr2 members demonstrated varying degrees of expression among the individual Sprr2 members in different tissues. The correlation between the physical location of the genes in the Sprr2 locus and their expression patterns suggests multiple levels of controlled expression.

Animals↗
PubMed1999

Possible contribution to hepatocarcinogenesis of X transcript of hepatitis B virus in Japanese patients with hepatitis C virus.

Serological research suggests that hepatitis B virus (HBV) and hepatitis C virus (HCV) are associated with the development of hepatocellular carcinoma (HCC). It is unclear how genes of hepatitis viruses participate in hepatocarcinogenesis in patients infected with HCV. We investigated the expression of hepatitis virus-related RNAs in resected liver from 51 patients with HCV antibodies (Ab) and without hepatitis B surface antigen (HBsAg). mRNA transcripts of the genes HBx, HBc, HBs, nonstructural (NS) region 3 of HCV, the 5'-untranslated region (UTR) of HCV, and the 5'-UTR of hepatitis G virus (HGV) were amplified by reverse-transcription polymerase chain reaction (RT-PCR) with specific primers for each gene. The HBx transcript was detected in 19 (37%) tumors and in 8 (16%) specimens of noncancerous tissues (P =.014). The NS3 gene of HCV was detected in 35 (69%) tumors and 41 (80%) noncancerous tissues. HGV RNA was detected in 3 tumors (6%). Patients with HBx transcripts were younger than patients without HBx transcripts (P =.012). HBx transcripts were detected in 3 (33%) of 9 well-differentiated HCCs, in 8 (31%) of 26 moderately differentiated HCCs, and in 8 (50%) of 16 poorly differentiated HCCs. Codon 130 (AAG) and codon 131 (GTC) of HBx were changed to ATG and ATC, respectively, in all HCCs with HBx transcripts. In conclusion, we found that the HBx gene was expressed in many HCCs; the gene might promote hepatocarcinogenesis in patients with HCVAb and without HBsAg, but HGV is not closely related to hepatocarcinogenesis in such patients.

Base Sequence↗
PubMed1999

Clinical need for both scintigraphy with technetium-99m GSA and per-rectal portal scintigraphy in some patients with chronic liver disease.

Scintigraphy with 99mTc-diethylenetriaminepentaacetate with galactosyl human serum albumin (99mTc-GSA) and per-rectal portal scintigraphy are useful for evaluating hepatic functional reserve and portal circulation, respectively. We did the procedures simultaneously in some patients to examine the relationship between hepatic functional reserve and portal circulation in chronic liver disease. Scintigraphy with 99mTc-GSA was done in 10 healthy subjects, 45 patients with chronic hepatitis, and 165 patients with cirrhosis. Fifty-seven patients (13 with hepatitis and 44 with cirrhosis) also underwent per-rectal portal scintigraphy with 99mTc-pertechnetate within two weeks. A receptor index was calculated by dividing the radioactivity of the liver region of interest (ROI) by that of the liver-plus-heart ROI at 15 min after the injection of 99mTc-GSA. The index of blood clearance was calculated by dividing the radioactivity of the heart ROI at 15 min by that of the heart ROI at 3 min. A solution containing 99mTc-pertechnetate was instilled into the rectum, and serial scintigrams were taken while radioactivity curves for the liver and heart were recorded sequentially. A per-rectal portal shunt index was determined by calculating the ratio of counts for the liver to counts for the heart integrated for 24 seconds immediately after the appearance of the liver time-activity curve. The median receptor index was lower for more severe liver disorders, increasing in the order of chronic hepatitis, compensated cirrhosis and decompensated cirrhosis, and the median index of blood clearance was higher. The median receptor index was significantly lower when a complication (varices, ascites, or encephalopathy) was present, and the median index of blood clearance was higher. The shunt index was correlated significantly with the two other indices, but these values for some one-third of the patients disagreed in either indices. Scintigraphy with 99mTc-GSA and per-rectal portal scintigraphy with 99mTc-pertechnetate are both needed for accurate assessment of the severity of chronic liver disease before treatment-making decisions, because in some patients, results are not correlated.

Administration, Rectal↗
PubMed1999

Two cases of focal nodular hyperplasia of the liver: value of scintigraphy with Tc-99m GSA and positron emission tomography with FDG.

Focal nodular hyperplasia (FNH) of the liver is relatively rare, and can be difficult to differentiate from other benign tumors arising in the liver. We describe a 23-year-old woman and a 25-year-old man with FNH. They were hospitalized for further evaluation of a space-occupying lesion in the liver. Scintigraphy with Tc-99m diethylenetriaminepentaacetic acid galactosyl human serum albumin (Tc-99m GSA) revealed increased radioactivity in the tumor in one patient and radioactivity similar to that in the normal part of liver in the other. F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) showed uptake similar to that of the normal liver in both patients. FNH was diagnosed on the basis of angiographic findings and histological findings in liver biopsy specimens. Our results show that scintigraphy with Tc-99m GSA and FDG-PET may provide information helpful in the diagnosis of FNH.

Adult↗
PubMed1999

Nuclear translocation of Fos is stimulated by interaction with Jun through the leucine zipper.

Jun and Fos, b-ZIP transcription factors, form a heterodimer and bind to DNA enhancer elements, thereby regulating the expression of target genes. The present study was undertaken to investigate the molecular mechanism underlying nuclear translocation of the Jun/Fos complex. For this purpose, normal rat kidney cells were microinjected with a DNA expression vector containing wild-type or mutant c- or v-jun together with c- or v-fos, followed by detection of the subcellular localization of Jun or Fos by immunofluorescence staining. The nuclear accumulation of Fos was markedly enhanced by the presence of wildtype Jun, but not by Jun mutants lacking nuclear targeting or zipper dimerization functions, implying that Jun and Fos mutually interact via their leucine zippers and translocate from the cytoplasm to the nucleus using the markedly stronger nuclear localization signal of Jun.

Animals↗
PubMed1999

Clinical usefulness of conjugated bilirubin levels in patients with acute liver diseases.

We used a specific method to measure conjugated bilirubin levels in patients with acute liver diseases to examine its clinical usefulness. Conjugated and total bilirubin levels were measured in 102 samples obtained from six patients with acute liver diseases (three with fulminant hepatic failure, one with acute severe hepatitis and two with acute hepatitis; see text for criteria). Total and conjugated bilirubin levels were measured with Iatro T (total)-Bil and D (direct)-Bil kits (Iatron Laboratories Tokyo, Japan) and with conventional Nescauto T(total)-Bil and D(direct)-Bil VE kits (Nippor Shoji, Osaka, Japan). The Iatro D-Bil kit measures conjugated bilirubin correctly, while the Nescauto D-Bil VE kit measures some nonconjugated bilirubin and delta bilirubin as well as conjugated bilirubin. Total bilirubin levels determined by the two methods showed good correlation. The conjugated bilirubin level measured with the Iatro D-Bil kit was strongly correlated with the direct bilirubin level measured with the Nescauto D-Bil VE kit, but there was no correlation between the conjugated-to-total bilirubin ratio and the direct-to-total bilirubin ratio. When we examined the changes in bilirubin levels in our patients with respect to outcome, we found that the two patients in whom the ratio of conjugated-to-total bilirubin exceeded 0.3 died, while all four patients in whom the ratio remained below 0.3 survived. The ratio of direct-to-total bilirubin was unrelated to outcome. The conjugated bilirubin level measured with the Iatro kits was therefore considered useful for the diagnosis and follow-up of acute liver diseases.

Acute Disease↗
PubMed1999

Calcitriol for bone loss in patients with primary biliary cirrhosis.

Because osteoporosis is a common complication of primary biliary cirrhosis, we evaluated the effects of calcitriol (1alpha, 25-dihydroxyvitamin D3) on bone mineral density in 34 women with primary biliary cirrhosis (stage I disease in 16 patients, stage II in 9, stage III in 4, and stage IV in 5). Patients were assigned randomly to receive calcitriol (0.5mg twice a day) or not. Bone mineral density of the lumbar vertebrae was measured by dual-energy X-ray absorptiometry at least twice during a period of 12-43 months. The mean annual change in bone mineral density was 0.1% in the treatment group and -3.1% in the control group. The median annual change (with 25th and 75th percentiles) in bone mineral density was 0.3% (-0.5%, 1.9%) in the treated group and -3.1% (-4.1%, -2.1%) in the control group. This difference between the two groups was significant (P = 0.0007, Mann-Whitney U-test). Our findings suggest that calcitriol prevents bone loss and may be an effective treatment for osteoporosis in patients with primary biliary cirrhosis.

Absorptiometry, Photon↗
PubMed1999

Prevalence of TT virus in patients with fulminant hepatic failure in Japan.

A novel virus (TT virus) was isolated from patients with posttransfusion hepatitis of unknown etiology. We studied the prevalence of TT virus in 26 patients with fulminant hepatic failure without risk factors, including blood transfusion, and also examined 106 healthy blood donors as controls. We assayed serum TT virus DNA by seminested polymerase chain reactions and also examined the genotypes of this virus. Serum was obtained at admission from patients with fulminant hepatic failure. Serum samples at admission from seven (27%) of the 26 patients were positive for TT virus DNA. There were no differences in clinical findings, duration from onset to coma, or results of laboratory tests in patients with and without TT virus DNA. However, all 7 patients with TT virus died, whereas 9 of the 19 patients without TT virus died. The outcome for patients with fulminant hepatic failure and TT virus was significantly worse than for patients without the virus (P = 0.0227). TT virus was also detected in 29 (27%) of the 106 healthy blood donors. The genotype of the TT virus was mainly 1a in both groups. There were no differences in the rate of positivity and the genotypes of TT virus between patients with fulminant hepatic failure and healthy blood donors. TT virus infection may not cause severe hepatitis, such as fulminant hepatic failure, but it may indicate a poor outcome in such patients.

Adolescent↗
PubMed1999

Biochemical markers of bone turnover during hormone replacement therapy.

OBJECTIVE: To assess the clinical usefulness of bone turnover markers, including serum osteocalcin (OC), urinary pyridinoline (Pyr) and deoxypyridinoline (D-Pyr), in monitoring and predicting bone response to hormone replacement therapy (HRT). METHOD: The relationships between baseline levels or changes in markers and change in lumbar bone mineral density were examined in 21 surgically-induced postmenopausal women. RESULTS: Levels of OC, Pyr and D-Pyr in the estrogen effective group (responders) significantly decreased during HRT and baseline levels of Pyr and D-Pyr in responders were significantly higher than those in premenopausal women. CONCLUSION: Bone turnover markers were useful in monitoring the bone effect of HRT and baseline levels of markers reflect subsequent bone response to HRT.

Amino Acids↗
PubMed1999

Expression of cyclins D1, D2 and E correlates with proliferation of rat stellate cells in culture.

BACKGROUND/AIMS: Regulation of cell cycle progression of cultured rat stellate cells was studied. METHODS: DNA synthesis was determined by the uptake of [3H]thymidine or 5-bromo-2'-deoxyuridine. Cell cycle distribution was analyzed using FACScan of cellular DNA stained with propidium iodide. Expression of cyclins and cyclin-dependent kinase 4 was evaluated by Western and Northern blotting. RESULTS: DNA synthesis of primary-cultured stellate cells was found to accelerate 48 h after plating. Cell cycle analysis revealed that more than 93% of the cells were in G0/G1 phase during the first 48 h after plating. The cell population in S phase abruptly increased to about 16% 72 h after culture and shifted to G2/M phase thereafter. The level of proteins and mRNAs for cyclins D1, D2 and E started to increase 48 h after culture with a concomitant expression of platelet-derived growth factor receptor beta, while the level of cyclin-dependent kinase 4 and its mRNA remained unchanged. On the other hand, stellate cells remained in G1 phase when they were cultured in the presence of 3-isobutyl-1-methylxanthine or dibutyryl cAMP after plating. Attenuation of the expression of cyclins D1, D2 and E and platelet-derived growth factor receptor beta, but not cyclin-dependent kinase 4 was found in stellate cells cultured with these agents. Further analysis revealed that LY294002, a selective inhibitor of phosphatidylinositol 3-kinase, suppressed DNA synthesis and cyclin D1 expression in a dose-dependent manner without affecting platelet-derived growth factor receptor beta expression. CONCLUSIONS: Induction of G1 cyclins may play crucial roles in cell cycle transition of cultured stellate cells from G1 to S. Expression of platelet-derived growth factor receptor beta and activation of phosphatidylinositol 3-kinase may be involved in the process.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Effects of the serotonin2A/2C receptor agonist and antagonist on phencyclidine-induced dopamine release in rat medial prefrontal cortex.

1. Systemic administration of PCP (7.5 mg/kg, i.p.) produced a greater increase in extracellular DA levels in the mPFC than in the STR and NAC, as determined by in vivo microdialysis of awake, freely moving rats. Preferential activation by PCP of prefrontal DA neurons may be, at least in part, the basis for the pathophysiology of PCP-induced psychosis as well as schizophrenia. 2. Recent studies suggest a possible involvement of 5-HT2A receptors in the pathophysiology and treatment of schizophrenia. This study was designed to examine whether and how 5-HT2A receptors modulate PCP-induced DA release in the mPFC. 3. The 5-HT2A/2C receptor agonist (+/-)-DOI (2.5 mg/kg, but not 0.75 mg/kg, i.p.), administered 60 min prior to PCP, significantly attenuated the PCP-induced increase in extracellular DA levels. Pretreatment of the 5-HT2A/2C receptor antagonist ritanserin (1.0 and 5.0 mg/kg, i.p.), administered 60 min prior to PCP, did not influence the PCP-induced increase. When administered alone, neither DOI (2.5 mg/kg) nor ritanserin (1.0 mg/kg) affected basal extracellular DA levels in the mPFC. 4. The NMDA receptor antagonist MK-801 (1.0 mg/kg, i.p.) also increased extracellular DA levels in the mPFC, but this effect was unaffected by pretreatment with DOI (2.5 mg/kg). 5. These results suggest that the stimulation of 5-HT2A/2C receptors may inhibit DA release in the mPFC when it is facilitated by PCP. Other than the NMDA receptor-mediated mechanism may also be involved in the neurochemical interaction between 5-HT2A receptors and PCP in the mPFC.

Amphetamines↗