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Biomedical subjects

Kazuaki Chayama

Publications and source records attributed to Kazuaki Chayama.

At least 19 recordsLinked to original sources
PubMed2007

Clinical features and prognosis of patients with extrahepatic metastases from hepatocellular carcinoma.

AIM: To assess the clinical features and prognosis of 151 patients with extrahepatic metastases from primary hepatocellular carcinoma (HCC), and describe the treatment strategy for such patients. METHODS: After the diagnosis of HCC, all 995 consecutive HCC patients were followed up at regular intervals and 151 (15.2%) patients were found to have extrahepatic metastases at the initial diagnosis of primary HCC or developed such tumors during the follow-up period. We assessed their clinical features, prognosis, and treatment strategies. RESULTS: The most frequent site of extrahepatic metastases was the lungs (47%), followed by lymph nodes (45%), bones (37%), and adrenal glands (12%). The cumulative survival rates after the initial diagnosis of extrahepatic metastases at 6, 12, 24, and 36 mo were 44.1%, 21.7%, 14.2%, 7.1%, respectively. The median survival time was 4.9 mo (range, 0-37 mo). Fourteen patients (11%) died of extrahepatic HCC, others died of primary HCC or liver failure. CONCLUSION: The prognosis of HCC patients with extrahepatic metastases is poor. With regard to the cause of death, many patients would die of intrahepatic HCC and few of extrahepatic metastases. Although most of HCC patients with extrahepatic metastases should undergo treatment for the primary HCC mainly, treatment of extrahepatic metastases in selected HCC patients who have good hepatic reserve, intrahepatic tumor stage (T0-T2), and are free of portal venous invasion may improve survival.

Adult↗
PubMed2007

Lymphatic vessel density at the site of deepest penetration as a predictor of lymph node metastasis in submucosal colorectal cancer.

PURPOSE: Lymph node metastasis is an important factor that influences curability after endoscopic treatment of submucosal colorectal cancer. This study was designed to determine the usefulness of identification of lymphatic vessels by immunohistochemistry in predicting lymph node metastasis of submucosal colorectal cancer. METHODS: Lymphatic involvement was assessed by hematoxylin and eosin staining and podoplanin immunostaining on samples resected from 268 patients with submucosal colorectal cancer. Lymphatic vessel density was estimated by two investigators by average count of three fields (x200) in the area of greatest number of podoplanin-positive capillaries at the site of deepest submucosal penetration. Relations with other clinicopathologic parameters also were investigated. RESULTS: Lesions with high lymphatic vessel density (> or =9 vessels per field) showed a significantly greater incidence of lymph node metastasis than did those with low lymphatic vessel density (<9 vessels per field; 23.3 vs. 8.4 percent). By multivariate analysis, lymphatic vessel density was determined to be an independent risk factor for lymph node metastasis of submucosal colorectal cancer (P = 0.0044). Lymphatic vessel density also correlated with tumor budding and the degree of inflammation at the invasive front. CONCLUSIONS: Identification of lymphatic vessels by podoplanin immunostaining provides objective and accurate evaluation of lymphatic involvement. Lymphatic vessel density at the site of deepest penetration is a useful predictor of lymph node metastasis of submucosal colorectal cancer.

Colorectal Neoplasms↗
PubMed2007

Non-SCN5A related Brugada syndromes: verification of normal splicing and trafficking of SCN5A without exonic mutations.

Recently, it has been reported that under 20% of Brugada syndrome cases are linked to SCN5A mutations. The purpose of this study was to clarify whether abnormalities other than exonic mutations, such as splicing disorders, decreased mRNA expression levels, or membrane transport abnormalities of SCN5A, play a role in the pathogenesis of Brugada syndrome. We analyzed all SCN5A exons and splice sites using genomic DNA from 23 Brugada syndrome patients. We also analyzed the mRNA obtained from RV cardiomyocytes using real time PCR and sequencing, to study the expression levels and splicing patterns of SCN5A. The localization of SCN5A was examined by immunofluorescence analysis. A de novo heterozygous G to A transversion in a 5' splice junction of the intron between exons 21 and 22 was detected in 1 patient. In the mRNA analysis of Brugada syndrome patients without a mutation of SCN5A no splicing abnormalities were detected, and the SCN5A mRNA levels were similar to those of normal controls. Immunofluorescence analyses revealed that SCN5A is located on the surface membrane not only in the RV cardiomyocytes of normal controls but also in those with Brugada syndrome. We can confirm that some Brugada syndrome patients without exonic mutations in SCN5A had no other SCN5A abnormalities, including any involving the location of the SCN5A protein. These results suggest the involvement of other proteins in the pathogenesis in Brugada syndrome.

Adult↗
PubMed2006

Defensive medicine practices among gastroenterologists in Japan.

AIM: To clarify the prevalence of defensive medicine and the specific defensive medicine practices among gastroenterologists in Japan. METHODS: A survey of gastroenterologists in Hiroshima, Japan, was conducted by mail in March 2006. The number of gastroenterologists reporting defensive medicine behaviors or changes in their scope of practice and the reported defensive medicine practices, i.e., assurance and avoidance behaviors, were examined. RESULTS: A total of 131 (77%) out of 171 gastroenterologists completed the survey. Three (2%) respondents were sued, and most respondents (96%) had liability insurance. Nearly all respondents (98%) reported practicing defensive medicine. Avoidance behaviors, such as avoiding certain procedures or interventions and avoiding caring for high-risk patients, were very common (96%). Seventy-five percent of respondents reported often avoiding certain procedures or interventions. However, seasoned gastroenterologists (those in practice for more than 20 years) adopted avoidance behaviors significantly less often than those in practice for less than 10 years. Assurance behaviors, i.e., supplying additional services of marginal or no medical value, were also widespread (91%). Sixty-eight percent of respondents reported that they sometimes or often referred patients to other specialists unnecessarily. CONCLUSION: Defensive medicine may be highly prevalent among gastroenterologists throughout Japan, with potentially serious implications regarding costs, access, and both technical and interpersonal quality of care.

Defensive Medicine↗
PubMed2006

Basis of decreased risk of gastric cancer in severe atrophic gastritis with eradication of Helicobacter pylori.

Helicobacter pylori infection induces chronic gastritis and lowers gastric juice ascorbic acid concentrations. We investigated how H. pylori eradication affected multiple variables that could prevent or delay development of new or occult gastric cancer in patients with early gastric cancer treated by endoscopic mucosal resection. Gastric juice pH, nitrite concentrations, and total vitamin C concentrations, serum concentrations of vitamin C and specific H. pylori antibody, and intensity of neutrophil infiltration in gastric mucosa were determined before and after successful H. pylori eradication. Successful eradication increased acid output and ascorbic acid secretion into gastric juice, accompanied by disappearance of polymorphonuclear infiltration from the surface epithelium and decreased gastric juice nitrite concentrations. Our data suggest that H. pylori eradication decreases the nitrosation rate as the ratio of vitamin C to nitrite increases. This decreases reactive oxygen species and nitric oxide, eliminating their damaging effect on DNA and reducing cell turnover.

Aged↗
PubMed2006

Medical malpractice litigation related to gastrointestinal endoscopy in Japan: a two-decade review of civil court cases.

AIM: To examine the allegations in malpractice litigations related to gastrointestinal endoscopy in Japan. METHODS: A retrospective review of cases tried in the civil court system during the 21-year period from 1985 to 2005, identified in a computerized legal database, was undertaken. RESULTS: Eighteen malpractice litigations and a total of 30 allegations were identified. Of the 18 (44%) malpractice litigations, 8 (44%) were related to esophagogastroduodenoscopy, 4 (22%) to colonoscopy, 4 (22%) to endoscopic sphincterotomy, and 2 (11%) to endoscopic retrograde cholangiopancreatography. Seventeen (94%) cases pertained to complications, and the remaining (6%) case pertained to misdiagnosis. In 10 cases, the patient died of the complications. Allegations were categorized as: (1) performance error during the endoscopic procedure (n = 12, 40%); (2) lack of informed consent (n = 9, 30%); (3) performance error during the treatment after the endoscopic procedure (n = 4, 13%); (4) premedication error (n = 3, 10%); (5) diagnostic error (n = 1, 3%); and (6) indication error for the endoscopic procedure (n = 1, 3%). CONCLUSION: These data may aid in the design of risk prevention strategies to be used by gastrointestinal endoscopists.

Endoscopy, Gastrointestinal↗
PubMed2006

Successive, rapid recurrences of in-stent restenoses in a woman with angina pectoris.

A 62-year-old woman was admitted because of chest pain. Coronary angiography demonstrated stenosis of the left anterior descending coronary artery, where two bare metal stents had been implanted. Over 5 months in-stent restenosis occurred four times, and was treated at first with angioplasty but finally with two sirolimus-eluting stent insertions. Six months after the second insertion, angiography showed restenosis within one stent. The mechanism underlying this succession of rapid restenoses is unknown, but sirolimus-eluting stents appeared to show relative resistance.

Angina Pectoris↗
PubMed2006

Effects of acute administration of caffeine on vascular function.

Caffeine is the most widely used pharmacologic substance in the world. It is found in common nonessential grocery items (e.g., coffee, tea, cocoa, and chocolate). The effects of caffeine on cardiovascular diseases, including hypertension, remain controversial, and there is little information on its direct effect on vascular function. The purpose of this study was to determine the effect of caffeine on endothelial function in humans. This study was a double-blind, randomized placebo and active drug study. Forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and to sodium nitroprusside, an endothelium-independent vasodilator, were evaluated in healthy young men before and after the oral administration of caffeine 300 mg (n = 10) or placebo (n = 10). FBF was measured by using a strain-gauge plethysmograph. Caffeine significantly increased systolic and diastolic blood pressures by 6.0 +/- 6.0 and 2.6 +/- 3.1 mm Hg (p <0.05), respectively, but did not alter heart rate or baseline FBF. Caffeine augmented the FBF responses to ACh from 21.2 +/- 7.1 to 26.6 +/- 8.1 ml/min/100 ml tissue (p <0.05), whereas sodium nitroprusside-stimulated vasodilation was not altered by caffeine administration. The intra-arterial infusion of N(G)-monomethyl-L-arginine, a nitric oxide synthase inhibitor, abolished the caffeine-induced augmentation of FBF response to ACh. In the placebo group, the ACh- and sodium nitroprusside-stimulated vasodilation was similar before and after the follow-up period. In conclusion, these findings suggest that the acute administration of caffeine augments endothelium-dependent vasodilation in healthy young men through an increase in nitric oxide production.

Acetylcholine↗
PubMed2006

Feasibility of freeze-dried sera for serological and molecular biological detection of hepatitis B and C viruses.

We compared hepatitis B virus (HBV) surface antigen, anti-hepatitis C virus (HCV) antibody, and HCV RNA quantification in frozen and freeze-dried serum samples to assess the usefulness of freeze-dried sera for detection of HBV and HCV. The results indicated that freeze-dried sera as well as frozen sera can be useful for serological and molecular biological analyses of HBV and HCV.

Freeze Drying↗
PubMed2006

Advantage of endoscopic submucosal dissection compared with EMR for early gastric cancer.

BACKGROUND: In EMR of early gastric cancer (EGC), en bloc resection reduces the risk of residual cancer. Endoscopic submucosal dissection (ESD) now allows en bloc resection of large EGCs. OBJECTIVE: To retrospectively determine whether ESD is more advantageous than EMR for EGCs. DESIGN: EMR (825 lesions, 711 patients) or ESD (195 lesions, 185 patients) was performed. The en bloc resection rate, histologically complete resection rate, operation time, complications, and local recurrence rate were studied in relation to ulceration. SETTING: Hiroshima University Hospital. PATIENTS: Subjects comprised 896 patients in whom 1020 EGCs were resected endoscopically from 1990 to 2004. RESULTS: In cases without ulceration, en bloc and histologically complete resection rates were significantly higher with ESD than with EMR, regardless of tumor size. The frequency of ulceration did not differ significantly between groups. Average operation time was significantly longer for ESD than for EMR, regardless of tumor size. Also, regardless of ulceration, the incidence of intraoperative bleeding was significantly higher with ESD (22.6%) than with EMR (7.6%). Delayed bleeding did not differ. In cases with ulceration, the incidence of perforation was significantly higher with ESD (53.8%) than with EMR (2.9%). Local recurrences were treated by incomplete EMR (en bloc, 2.9%; piecemeal, 4.4%). No patient experienced recurrence after ESD. CONCLUSIONS: ESD increased en bloc and histologically complete resection rates and may reduce the local recurrence rate. Increased operation time and complication risks with ESD in comparison with EMR remain problematic. Special measures are necessary for ESD of ulcerated lesions to reduce the rates of perforation and incomplete resection.

Biopsy↗
PubMed2006

Emergence of a novel lamivudine-resistant hepatitis B virus variant with a substitution outside the YMDD motif.

Lamivudine is a major drug approved for treatment of chronic hepatitis B virus (HBV) infection. Emergence of drug-resistant mutants with amino acid substitutions in the YMDD motif is a well-documented problem during long-term lamivudine therapy. Here we report a novel lamivudine-resistant strain of HBV with an intact YMDD motif, which included an amino acid substitution, rtA181T, in the reverse transcriptase (RT) domain of HBV polymerase. The substitution also induced a unique amino acid substitution (W172L) in the overlapping hepatitis B surface (HBs) protein. The YMDD mutant strains were not detected even by using the sensitive peptide nucleic acid-mediated PCR clamping method. The detected nucleotide substitution was accompanied by the emergence of an additional nucleotide substitution that induced amino acid change (S331C) in the spacer domain. The rtA181T mutant strain displayed a threefold decrease in susceptibility to lamivudine in in vitro experiments in comparison with the wild type. In vivo analysis using human hepatocyte-chimeric mice confirmed the resistance of this mutant strain to lamivudine. We developed a method to detect this novel rtA181T mutation and a previously reported rtA181T mutation with the HBs stop codon using restriction fragment length polymorphism PCR and identified one patient with the latter pattern among 40 patients with lamivudine resistance. In conclusion, although the incidence is not high, we have to be careful regarding the emergence of lamivudine-resistant mutant strains with intact YMDD motif.

Adenine↗
PubMed2006

Evolution of hepatitis C virus quasispecies during ribavirin and interferon-alpha-2b combination therapy and interferon-alpha-2b monotherapy.

OBJECTIVE: Ribavirin and interferon combination therapy is more effective than interferon monotherapy in patients with chronic hepatitis C virus (HCV) infection. To test the hypothesis that ribavirin induces nucleotide substitutions in the viral genome and reduces viral load by forcing it into error catastrophe in the combination therapy, we investigated the molecular evolution of HCV quasispecies in 3 patients who received combination therapy and 2 patients who received interferon monotherapy. METHODS: The quasispecies were analyzed before and after therapy by sequencing at least 8 clones in five regions of the HCV genome; 5' untranslated region, EI, E2, NS5A and NS5B. RESULTS: Marked genetic drift was observed in the NS5A and NS5B regions in patients treated with combination therapy. However, genetic distances between clones obtained after therapy were closer than those obtained before therapy. CONCLUSION: Our results suggest that the combination therapy modified HCV quasispecies, but that this did not reflect the induction of error catastrophe by ribavirin. Modification of quasispecies by this therapy requires further investigation in a larger number of patients to elucidate the possible mechanism of viral resistance against the combination therapy.

5' Untranslated Regions↗
PubMed2006

Prolonged negative HCV-RNA status led to a good outcome in chronic hepatitis C patients with genotype 1b and super-high viral load.

OBJECTIVE: We examined whether a sustained negative HCV-RNA status for 48 weeks affects the outcome in patients with genotype 1b and super-high viral load, and also investigated whether the outcome is affected by the induction therapy of twice-daily pre-administrated interferon (IFN)-beta. METHODS: 78 eligible patients were divided into four groups. 40 were patients assigned to the short treatment protocol. 13 patients received 3 MU IFN-beta twice daily for 2 weeks followed by IFN-alpha2b+ribavirin for 22 weeks (beta-induction group: group 1). 27 patients received IFN-alpha2b+ribavirin for 24 weeks (standard combination group: group 2). 38 patients were assigned to the maintenance treatment protocol. All of the 13 in the beta-induction group (group 3) and 21 of 25 patients in the standard combination group (group 4) who were negative HCV-RNA PCR at week 24 had IFN monotherapy to maintain a negative HCV-RNA result for 48 weeks. RESULTS: An HCV-RNA-negative status at week 24 was observed in 96% (25/26) of groups 1 and 3 versus in 79% (41/52) of groups 2 and 4 (p<0.01). The sustained virological response (SVR) was 38% (5/13) in group 1 and 11% (3/27) in group 2 (p<0.05). In the maintenance treatment, SVR was observed in 46% (6/13) of group 3 and 32% (8/25) of group 4 (NS). CONCLUSIONS: A sustained negative HCV-RNA status for 48 weeks might be associated with viral elimination in patients with genotype 1 and super-high viral load.

Adult↗
PubMed2006

Anti-fibrogenic function of angiotensin II type 2 receptor in CCl4-induced liver fibrosis.

The renin-angiotensin system (RAS) contributes to fibrogenesis in a variety of organs. We recently showed that a lack of angiotensin (Ang) II type 1 (AT1) receptor activity reduces liver fibrosis. In this study, we investigated whether the Ang II type 2 (AT2) receptor is implicated in the development of liver fibrosis. A comparison was made between AT2-receptor knockout (AT2KO) and wild type (WT) mice after 4 weeks of treatment with carbon tetrachloride (CCl4). Fibrosis was assessed by Azan-Mallory staining and hepatic hydroxyproline (HP) content. The expression of fibrogenic mRNA was measured by real-time quantitative reverse-transcription polymerase chain reaction (PCR). Liver fibrosis evaluated by regular histological analyses and immunohistochemical alpha-SMA staining was observed in both groups of mice. The extent of fibrosis was greatest in the AT2KO mice. Fibrosis was associated with increases in hepatic HP content and mRNA expression for TGF-beta1 and alpha-SMA, as well as an increase in hepatic TBARS. These findings suggest that CCl4 induces oxidative stress which leads to activation of hepatic stellate cells (HSCs). These changes were considerably more pronounced in the AT2KO mice than the WT mice. Taken together, we conclude that AT2 signal has anti-fibrogenic and/or cytoprotective effects on oxidative stress-induced liver fibrosis. We therefore suggest that RAS-associated liver fibrogenesis may be determined by the balance between AT1 and AT2 signals.

Animals↗
PubMed2006

A case of multiple hepatic peribiliary cysts which contributed to the obstructive jaundice and led to liver failure at the young man with von Recklinghausen's disease.

We treated a young man with obstructive jaundice, in whom multiple hepatic peribiliary cysts were detected at autopsy. He had been diagnosed with von Recklinghausen's disease in early childhood and had undergone surgery for a ventricular septal defect with massive blood transfusion at the age of 4 years. Examination at the age of 21 revealed prominent splenomegaly and a low platelet count. He underwent splenectomy and liver cirrhosis was confirmed by open biopsy of the liver. He was followed up at a local hospital and was admitted several times. When he was 41 years old, he was transferred to our hospital with severe jaundice and hepatic encephalopathy. Computed tomography showed marked dilation of the intrahepatic bile ducts and liver function tests showed that jaundice was mainly due to an increase of direct bilirubin. Despite endoscopic nasobiliary drainage, plasma exchange, and continuous hemodiafiltration, he died of hepatic failure after 5 days. At autopsy, multiple hepatic peribiliary cysts were found. Although peribiliary cysts have generally been considered to cause no symptoms, this report describes a patient with multiple hepatic peribiliary cysts which appear to have been responsible for the progression of obstructive jaundice.

Journal Article↗
PubMed2006

Serine palmitoyltransferase inhibitor suppresses HCV replication in a mouse model.

Serine palmitoyltransferase (SPT) is a first-step enzyme in the sphingolipid biosynthetic pathway. Myriocin is an inhibitor of SPT and suppresses replication of the hepatitis C virus (HCV) replicon. However, it is still unknown whether this SPT inhibitor suppresses HCV replication in vivo. We investigated the anti-HCV effect of myriocin against intact HCV using chimeric mice with humanized liver infected with HCV genotype 1a or 1b. We administered myriocin into HCV infected chimeric mice and succeeded in reducing the HCV RNA levels in serum and liver to 1/10-1/100 of the levels prior to the 8 day treatment. Furthermore, combined treatment with pegylated interferon reduced the HCV RNA levels to less than 1/1000 of the control levels. We strongly suggest that suppression of SPT reduces HCV replication, and therefore that the SPT inhibitor is potentially a novel drug in the treatment of HCV infection.

Animals↗
PubMed2006

Helicobacter pylori infection is the major risk factor for gastric inflammation in the cardia.

We attempted to clarify the pathogenesis of gastric inflammation in the cardia. Eighty Japanese participated in this study. Biopsy specimens of the gastric antrum, corpus, and cardia (1 cm from the squamocolumnar junction) were obtained, and histological gastritis was evaluated. Cardiac inflammation was also evaluated using magnifying gastroscopy. We examined Helicobacter pylori infection, gastric juice pH/bile acid (BA), serum pepsinogen and gastrin levels, gastroesophageal reflux disease (GERD), and habitual smoking and assessed the relations between these factors and cardiac inflammation. The prevalence of H. pylori infection was statistically higher in patients with cardiac inflammation than in those without inflammation (P < 0.05). The relationship was also demonstrated by magnifying gastroscopy. Cardiac inflammation was linked to low acid output but not linked to the BA concentration or habitual smoking. Cardiac inflammation was more pronounced in patients without GERD. These results suggest that H. pylori is a major risk factor for cardiac inflammation in the Japanese.

Adult↗