Biomedical subjects

K Hamazaki

Publications and source records attributed to K Hamazaki.

At least 19 recordsLinked to original sources

PubMed2000

Heterotopic gastric mucosa in the gallbladder.

We report on a case of heterotopic gastric mucosa in the body of the gallbladder. A 39-year-old man, who was asymptomatic, visited our hospital because of a polypoid lesion in the gallbladder, discovered during a routine health screening. Ultrasonography (US) revealed a broad-based polypoid lesion 1.7 cm in diameter in the body of the gallbladder, which was free of gallstones. The gallbladder mass was faintly enhanced by helical computed tomography. Laparoscopic cholecystectomy was performed because of the possibility of malignancy. The specimen revealed a 1.7 x 1.3 cm polypoid lesion with deep delle in the body, with no gallstones in the gallbladder. Intraoperative frozen examination yielded a diagnosis of hyperplastic polyp of the gallbladder. Histologically, the polypoid lesion consisted of gastric fundic glands located in the whole wall of the gallbladder. The surrounding mucosa consisted of almost normal epithelium without any metaplastic changes. Postoperative technetium 99m-pertechnetate scintigraphy demonstrated no evidence of gastric heterotopia elsewhere in the body. We also review 18 other reports of heterotopic gastric mucosa in the gallbladder in the Japanese medical literature.

Adult↗

PubMed2000

Laparoscopic cholecystectomy: experience with 150 consecutive patients in Kurashiki.

One hundred and fifty consecutive patients who underwent laparoscopic cholecystectomy (LC) in Kurashiki between March 1991 and December 1997 were studied in order to examine intraoperative procedures, and complications, especially with regard to bile duct injuries and acute cholecystitis, furthermore postoperative management. Nine out of the 150 cases were converted to open cholecystectomy, so that the overall success rate was 94%. One hundred and forty-six patients (97%) presented on an elective basis, and the remaining four patients were admitted as acute cholecystitis. One hundred and forty-four patients had gallbladder stones. All of seven patients had adenomyomatosis with stones (4 cases) and without stones (3 cases). Nine patients had benign polyps of the gallbladder with stones (6 cases) and without stones (3 cases). Seven patients with choledocholithiasis were treated successfully with endoscopic sphincterotomy preoperatively. In six out of eight patients with acute cholecystitis, among whom 4 were treated preoperatively with percutaneous transhepatic gallbladder aspiration (PTGBA), LC was conducted. Major complications included 3 cases of bile duct injuries (2%). Twenty cases (14) of bleeding encountered during operation were controlled easily under laparoscopy. Postoperative oral feeding was started in nearly all cases on the 1st postoperative day. In conclusion, LC seems to offer significant advantages to patient recovery but attention to bile duct injury and the judgement for the timing of conversion to open cholecystectomy is considered necessary for a successful LC.

Adolescent↗

PubMed1999

Oxygen concentration regulates NO-dependent relaxation of aortic smooth muscles.

Nitric oxide (NO) functions as an endothelium-derived relaxation factor and regulates vascular resistance. Recent studies in this laboratory(Arch.Biochem.Biophys.323, 27-32, 1995) revealed that the lifetime of NO significantly increased at physiologically low levels of oxygen concentrations and, hence, this gaseous radical strongly inhibited mitochondrial electron transport for a fairly long duration at low oxygen concentrations. The present work describes the effect of oxygen concentration on NO-induced relaxation and guanylate cyclase (GC) activity of endothelium-denuded aorta of the rat. Both NO and 2,2 '-(hydroxynitrosohydrazono)bis-ethanamine (NOC18), an NO donor, induced the relaxation of endothelium-denuded helical segments of rat aorta which were contracted by norepinephrine. NO-dependent relaxation of arterial specimens was enhanced by lowering oxygen concentration in the medium with concomitant increase in their cGMP levels. Anoxia induced the relaxation of the aorta by some NO-enhanceable and methylene blue-insensitive mechanism. These results suggested that local concentrations of oxygen might play important roles in the regulation of NO-dependent GC activity and vascular tonus of resistance arteries.

Animals↗

PubMed1999

Geranylgeranylacetone induces apoptosis in HL-60 cells.

Geranylgeranylacetone (GGA) induces apoptosis in human leukemia HL-60 cells in a dose- and time-dependent manner. This effect was completely prevented by the pan-caspase inhibitor z-Val-Ala-Asp(OMe) fluoromethylketone, thereby implicating the caspase cascade in the process. Prior to DNA fragmentation, GGA treatment markedly activated caspase-3(-like) proteases, which might be responsible for the observed apoptosis. In addition, GGA treatment interfered with the processing and membrane localization of Rap1 and Ras, and these changes may be a result of apoptosis. Moreover, nitric oxide donors significantly accentuated the GGA-induced apoptosis, suggesting that the apoptotic pathway induced by GGA might be regulated by a redox-sensitive mechanism. Taken together, these data suggest that the isoprenoid, GGA, is an effective inducer of apoptotic cell death in HL-60 cells.

Amino Acid Chloromethyl Ketones↗

PubMed1999

Role of nuclear lamins in nuclear segmentation of human neutrophils.

Nuclear breakdown leading to the formation of apoptotic bodies has been postulated to involve degradation of nuclear structural proteins, such as lamins A/C and B. Although nuclear segmentation occurs during the maturation of polymorphonuclear leukocytes (neutrophils), its mechanism is not known. We found that human neutrophils have lamin B but lack lamins A/C while mononuclear cells possess all three types of lamin as assessed by immunoblotting. Differentiation of human promyelocytic HL-60 cells into neutrophil-like cells was also accompanied by the down-regulation of lamins A/C but not of lamin B. Moreover, when compared with normal cells, neutrophils with the Pelger-Huët anomaly of nuclear hyposegmentation exhibited significantly lower activity of caspase-6, a lamin A/C-cleaving enzyme. Differentiated HL-60 cells showed higher activity of caspase-6 than that of untreated cells. These observations allow us to speculate that remodeling of nuclear lamins might underlie the mechanism for nuclear segmentation of neutrophils.

Apoptosis↗

PubMed1998

Cyclin E overexpression responsible for growth of human hepatic tumors with p21WAF1/CIP1/SDI1.

We examined a relationship between p21WAF1/CIP1/SDI1 and cell-cycle-related proteins in 12 human liver tumor cell lines (JHH-1, -2, -4, -5, -6, -7; HLE; HuH-7; Hep3B; PLC/PRF/5; HuH-6; HepG2). Seven (JHH-1, -2, -5, -6, -7; Hep3B; HepG2) out of eight cell lines having p21WAF1/CIP1/SDI1 protein overexpressed cyclin E protein, although one of them (JHH-5) overexpressed a reduced size of cyclin E. The rest (HuH-6) of the 8 cell lines with p21WAF1/CIP1/SDI1 showed a decreased expression of cyclin E. Four cell lines (JHH-4; HLE; HuH-7; PLC/PRF/5) deficient of p21WAF1/CIP1/SDI1 protein did not overexpress cyclin E protein. As to expression of the other cell-cycle-related proteins, cyclin A, cyclin D1, CDK2 or CDK4, no significant difference was detected among the 12 cell lines. These findings indicate that the human liver tumor cell lines which have the p21WAF1/CIP1/SDI1-inducible barriers of the cell cycle progression can go through the G1/S checkpoint by overexpressing cyclin E.

Blotting, Northern↗

PubMed1998

Reduced metastatic potential and c-myc overexpression of colon adenocarcinoma cells (Colon 26 line) transfected with nm23-R2/rat nucleoside diphosphate kinase alpha isoform.

Increased expression of nm23/nucleoside diphosphate kinase (NDP kinase) has been reported to be associated with both reduced metastatic potential in breast carcinoma and tumor progression in colon adenocarcinoma and lung adenocarcinoma. We examined effects of expression of nm23-R2 rat NDP kinase alpha isoform on mouse adenocarcinoma cells (Colon 26 line) and found a significant reduction of metastatic potential along with overexpression of c-myc. We also found that the proliferation rate of the transformed cells was the same as that of the control cells in culture. These results indicate that the cell growth potential in vitro is irrelevant to metastatic potential of the cells in vivo.

Adenocarcinoma↗

PubMed1997

Comparison of cellular characteristics between human hepatoma cell lines with wild-type p53 and those with mutant-type p53 gene.

Characteristics of human hepatoma cell lines with the wild-type p53 were compared with those of human hepatoma cell lines with the mutant-type p53. The p21 protein located downstream of p53 was expressed in cell lines with the wild-type p53 but was not expressed in cell lines with the mutant-type p53. As to other tumor suppressor genes such as p16 and p27, there was no difference in their expression between both types of cell lines. In addition, no marked difference was observed in the activities of CDK2 and CDK4 between cell lines with the wild-type and the mutant-type p53. Phosphorylated Rb protein was detected in all cell lines except the HLE line, indicating that this cell line may have a deletion of and/or a mutation of the Rb gene. These results indicate that abnormalities of tumor suppressor genes other than p53, p16, p27, and Rb may be involved in hepatocarcinogenesis. The population doubling time of the wild-type p53 cells was significantly longer than that of the mutant p53 cells. Neither type of cell line showed a specific chromosome distribution which would indicate karyotype instability. The cell lines expressing the wild-type p53 produced tumors at lower frequency than those with the mutant p53 gene. Although there was no significant difference in effects of TGF-beta 1, EGF, cholera toxin, and db-cAMP on cell growth between the two types of cells, all three cell lines with the wild-type p53 were resistant to cytotoxicity of TNF-alpha, while two of the three with the mutant p53 were very sensitive to its cytotoxic effects.

Animals↗

PubMed1997

Molecular mechanisms of apoptosis in HL-60 cells induced by a nitric oxide-releasing compound.

Nitric oxide (NO) generated from 1-hydroxy-2-oxo-3, 3-bis(2-aminoethyl)-1-triazene (NOC 18), an NO-releasing compound, induced monocytic differentiation of human promyelocytic leukemia HL-60 cells as assessed by expression of nonspecific esterases and morphologic maturation. Simultaneously, DNA fragmentation and morphological alterations typical of apoptosis were also induced. To investigate the mechanisms of apoptosis during differentiation of HL-60 cells induced by NO, the endogenous levels of Bcl-2 and Bax were assessed by immunoblotting. Treatment of cells with NOC 18 slightly reduced the level of Bcl-2 followed by Bax. These changes might be involved in the induction of apoptosis. The involvement of the activation of the interleukin-1 beta converting enzyme (ICE) family of proteases (caspases), such as ICE and CPP32, in the pathways was also investigated. CPP32, but not ICE, was strongly activated in response to NOC 18 stimulation, thereby implicating CPP32-like activity in the induction of apoptosis. Moreover, the possible involvement of tyrosine phosphorylation in apoptosis was investigated. Pretreatment of cells with herbimycin A, an inhibitor of tyrosine kinases, suppressed DNA fragmentation and CPP32-like activity, whereas pretreatment with vanadate, an inhibitor of tyrosine phosphatases, enhanced both parameters, suggesting that tyrosine phosphorylation might be involved in the pathways of apoptosis in HL-60 cells induced by NO.

Apoptosis↗

PubMed1997

Oxygen-dependent fragmentation of cellular DNA by nitric oxide.

Although active oxygen species and related metabolites, such as nitric oxide (NO), have been postulated to play important roles in the apoptosis of various cells, a precise mechanism leading to cell death remains to be elucidated. Recently we found that the lifetime of NO depends greatly on the concentration of environmental oxygen and that NO reversibly inhibits mitochondrial respiration and ATP synthesis; the inhibitory effect is stronger at physiologically low oxygen tension than under atmospheric conditions (Arch. Biochem. Biophys. 323, 27-32, 1995). The present work describes the effects of the NO-generating agent, 1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene (NOC 18) and oxygen tension on the respiration, ATP synthesis and apoptosis of HL-60 cells. When respiration was inhibited by NOC 18, cellular ATP levels decreased significantly and DNA fragmentation was elicited. Both events were enhanced by decreasing oxygen tension and suppressed by adding NO-trapping agents, such as 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO) and oxyhemoglobin. The fragmentation of cellular DNA was inhibited in a dose dependent manner by herbimycin A, a tyrosine kinase inhibitor. Fragmentation of the DNA of HL-60 cells was also induced either by peroxynitrite, superoxide or hydroxyl radical by some mechanism which was diminished by lowering the oxygen tension. These results indicated that the decrease in cellular ATP and activation of tyrosine kinase might play important roles in NO-induced apoptosis particularly under physiologically low oxygen tensions.

Adenosine Triphosphate↗

PubMed1997

Epidermal growth factor receptor in human hepatocellular carcinoma.

To determine whether a relationship exists between expression of epidermal growth factor receptor (EGFR) and clinicopathological characteristics of hepatocellular carcinoma (HCC), EGFR was examined in 25 patients surgically treated for HCC using [125I]1-labeled EGF binding assay. Six cases were classified as stage I, 12 as stage II, 4 as stage III, and 3 as stage IV. Partial hepatectomy was performed in 11 cases, segmentectomy in 6, and lobectomy in 8. The level of EGFR in HCC was 8.9 (14.6) fmol/mg protein in HCC and 11.4 (9.2) fmol/mg protein in the adjacent noncancerous diseased liver tissues, and EGFR level in HCC was significantly lower than that of noncancerous liver tissues. HCC stage I + II had significantly lower levels of EGFR compared with stage III + IV (p < 0.05). Our study showed no obvious correlation between EGFR levels and other pathologic characteristics, such as tumor diameter, Edmondson's grade, extracapsular invasion, and vascular invasion. There was no significant difference in EGFR level between DNA diploid and aneuploid tumors. These results suggest that EGFR is not a relevant oncogenic factor for HCC.

Adult↗

PubMed1996

Oxygen-dependent reversible inhibition of mitochondrial respiration by nitric oxide.

Effects of nitric oxide (NO) and NO generating agents, on the electron transport system of mitochondria were examined in a study of the mechanism and physiological importance of NO in energy metabolism. In the presence of various substrates, uncoupled respiration was inhibited by NO in manner which was both dose- and oxygen tension-dependent. Simultaneously measuring changes in cytochrome absorption spectra and respiration showed that the site of action of NO is cytochrome oxidase. Similar inhibition was also brought about by 1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene (NOC 18), an NO donor. Electron paramagnetic resonance (EPR) analysis revealed that inhibition of uncoupled respiration occurred only during the presence of NO in the reaction mixture. The inhibitory effect of NO was increased significantly by lowering the concentration of mitochondrial protein. No appreciable inhibition of respiration was observed in the presence of 3-morpholinosydnonimine (SIN-1), a peroxynitrite anion (ONOO-) generating reagent, but inhibition did occur in the presence of superoxide dismutase (SOD). These results indicate that NO reversibly interacts with mitochondria at complex IV thereby inhibiting respiration particularly under physiologically low oxygen tension and that de novo generated ONOO may have no significant effect under the present experimental conditions.

Animals↗

PubMed1996

[Dynamic MR and fat suppression imaging of pancreatic carcinoma].

The usefulness of dynamic MR and fat suppression imaging was investigated in 19 patients with pancreatic duct cell carcinoma. In addition to conventional spin echo imaging, dynamic MR and fat suppression imaging were performed. These images were evaluated for the detectability of lesions. The detectability of lesions was classified as good, fair or poor. On T1 weighted images, 26% of cases were evaluated as "good" and 32% as "fair". On dynamic MRI, 69% of cases were evaluated as "good" and 26% of cases as "fair". On pre- and postcontrast fat suppression images, 32% and 28%, respectively, were evaluated as "good", and 47% and 39% as "fair". Neither T2 weighted images nor enhanced T1 weighted images were useful. Direct comparison between dynamic MR and fat suppression images was also done. In 42% of cases, dynamic MR was superior to fat suppression images and in 42%, dynamic MRI was equal to fat suppression. In 16% of cases, fat suppression was superior to dynamic MRI. It was concluded that dynamic MR and fat suppression imaging were more useful than conventional spin echo imaging for the detection of pancreatic carcinoma.

Aged↗

PubMed1995

Hepatectomy under extracorporeal circulation.

BACKGROUND: Resection of hepatic tumors located near the confluence of the hepatic vein or invading the inferior vena cava has become technically feasible and relatively safe by using venovenous bypass. However, some technical problems remain to be solved. METHODS: We performed three cases of hepatic resection under extracorporeal circulation combined with hypothermic perfusion. RESULTS: An unexpected hemorrhage was observed in all three cases for different causes. The patient of case 2 died of liver failure developed from fatty liver. Bile duct stenosis was observed in cases 1 and 3. CONCLUSIONS: Although hepatectomy under total vascular exclusion by use of Biopump is now considered a safe procedure, attention should be paid when this procedure is performed because some technical problems still remain.

Blood Loss, Surgical↗

PubMed1995

Expression of Fas antigen and Bcl-2 protein in hepatocellular carcinoma.

Fas antigen (ag) is a cell surface protein known to trigger apoptosis in a variety of cells upon specific antibody binding. On the other hand, Bcl-2 protein, an oncogene product located at the mitochondrial inner surface, prolongs cell survival by blocking apoptosis. In this study we examined the expression of Fas ag and bcl-2 protein in 17 cases of hepatocellular carcinoma (HCC) to determine their role on HCC. By flow cytometric analysis, mean (SD) value of the expression of Fas ag on hepatocytes derived from normal liver, diseased liver (chronic hepatitis or liver cirrhosis) and HCC was 5.8 (4.7)%, 10.3 (6.9)%, and 24.0 (18.2)%, respectively. Fas ag expression on hepatoma cells was significantly greater than normal and diseased liver cells. The expression of Bcl-2 protein in normal liver, diseased liver and HCC was 4.3 (8.5)%, 0.8 (2.5)% and 2.1 (3.4)%, respectively, and the difference was not significant. These results suggest that induction of apoptosis may be a possible therapy against HCC.

Adult↗

PubMed1995

Lipid peroxidation in hepatocellular carcinoma.

In this study, we measured free radicals and thiobarbituric acid-reactive substances (TBARS) in hepatocellular carcinoma and in non-cancerous liver parenchyma. There was a higher concentration of free radicals in malignant tissue than in non-cancerous tissue. In contrast, the level of TBARS was significantly (P < 0.01) lower than non-cancerous liver parenchyma. These paradoxical results suggested that antioxidative enzyme activity and/or inhibition of lipid peroxidation were higher in hepatocellular carcinoma.

Carcinoma, Hepatocellular↗

PubMed1995

Laparoscopic cholecystectomy: a multicenter study of 17 hospitals.

A study of 1,254 laparoscopic cholecystectomies performed at 17 hospitals affiliated with the Liver, Gallbladder, and Pancreas Research Group of the First Department of Surgery at Okayama University was undertaken to assess the current status and safety of this procedure. The data for 336 patients, comprising the initial 20 laparoscopic cholecystectomies performed at each institution, were compared with the data from the remaining 918 patients. Comparison of the two groups revealed the following: 1. the rates of intraoperative conversion to open cholecystectomy were 11.3% and 5.1% (P < 0.05), 2. the complication rates were 5.7% and 3.4%, and 3. the rates of bile duct injury were 2.4% and 1.1%, respectively. Compared with the first group, the bile duct injuries resulting from a lack of experience decreased in the second group, however, the incidence of these injuries occurring during avulsion of the gallbladder in difficult cases increased. These results suggest that the experience acquired during the initial 20 laparoscopic cholecystectomies led to a reduction in the rate of intraoperative conversion to open cholecystectomy, but it did not reduce the rate of complications, and that the risk of bile duct injury was always present.

Cholecystectomy, Laparoscopic↗

PubMed1995

Effect of Picibanil (OK-432) on the scavenging effect of free radicals produced during liver regeneration in the rat.

We administered a biological response modifier Picibanil (OK-432), attenuated Streptococcus pyogenes, via the dorsal vein of the penis after 70% hepatectomy in rats, and clarified the scavenging effect of Picibanil on free radicals generated in the regenerating liver. A group of 5 rats was intravenously administered with 25 KE/kg of OK-432 after hepatectomy, while the control group was given saline after hepatectomy. Serum levels of aspartate aminotransferase and alanine aminotransferase and the value of thiobarbituric acid-reactive substances in serum and hepatic tissue after hepatectomy were serially measured, and these values were significantly lower in Picibanil treated animals than in control animals. Free radical production in the regenerating liver was also measured by electron spin resonance spectrometry, and OK-432 injection significantly reduced free radical production. These results suggested that OK-432 reduced hepatocellular damage in regenerating liver by inhibiting lipid peroxidation.

Alanine Transaminase↗