PubMed Health⌕ Search

Biomedical subjects

K Hamazaki

Publications and source records attributed to K Hamazaki.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1995

Measurement of hepatic blood flow using 111In colloid.

The reduced hepatic blood flow calculated from hepatic scintigram with 198Au colloid was elucidated as the primary responsible factor for postoperative hepatic insufficiency. However 198Au colloid is no longer in use because of the high levels of radiation. Although 99mTc-phytate behaves similarly to 198Au on imaging, there were discrepancies between the hepatic blood flow index (KL) value and the severity of cirrhosis determined by laboratory data or by histology. In the measurement of hepatic blood flow using a radioactive colloid, factors like organ distribution, stability and uniformity of the colloid particles influence the values. In the present study, a 111In colloid was prepared and administered to rats to investigate the usefulness: as much as 95.4 (0.8) [Mean (+/- SD)]% of the colloid accumulated in the liver at pH 6.8. The distribution of particle diameter was within a relatively narrow range with the peak at 0.2 to 0.4 microns. Moreover, the KL values were not affected by condition of the reticuloendothelial system. The values showed a significant correlation with the measurements of the hepatic tissue blood flow obtained by the hydrogen gas clearance method (gamma = 0.83, P < 0.001). Thus, the 111In colloid can be clinically used as a substitute for 198Au colloid in the preoperative examination for estimation of the limit of resection.

Animals↗
PubMed1995

31P nuclear magnetic resonance evaluation of rat liver preserved in UW solution.

A persistent problem in orthotopic liver transplantation is primary nonfunction (PNF) of the hepatic allograft. In an attempt to reduce the incidence of graft failure, the feasibility of pretransplant assessment of graft viability was investigated by 31P nuclear magnetic resonance (NMR) spectroscopy. The level of adenosine triphosphate (ATP) was measured as an indicator of liver function by 31P NMR spectroscopy after a 30 min normothermic reperfusion following cold-storage in University of Wisconsin (UW) solution. The mean +/- SD beta-ATP/Pi ratio after preservation for 0, 12, 24 or 48 h was 1.40 +/- 0.34, 0.85 +/- 0.27, 0.64 +/- 0.14 and 0.38 +/- 0.09, respectively. Significance was observed between 12h and 24h and between 12h and 48h of preservation. These results correlated well with the morphological changes in endothelial cells and sinusoidal lining cells examined by transmission electron microscopy. It is suggested strongly that microcirculatory disturbances due to endothelial cell injury impairs the recovery of ATP levels after reperfusion, and that ATP determination by 31P NMR spectroscopy, as a non-invasive modality, may help in the prediction of PNF after liver transplantation.

Adenosine↗
PubMed1995

Extracorporeal circulation and hypothermic perfusion for caval tumor thrombus complicating hepatocellular carcinoma: a case report.

A tumor thrombus complicating hepatocellular carcinoma developed in a 61-year-old male patient. Embolization of the right branch of portal vein was performed 2 weeks before operation. Curative resection of the tumor was performed on by extended hepatectomy plus in situ hypothermic perfusion of the liver and extracorporeal circulation. Postoperative course was uneventful until bile leakage occurred on the 11th postoperative day. A bile duct stenosis was diagnosed by cholangiogram, and hepaticojejunostomy was carried out. The patient recovered well without further complications. The pitfalls and technical problems encountered in this case are herein discussed.

Carcinoma, Hepatocellular↗
PubMed1995

Changes in IL-6 and IL-8 after hepatectomy in patients with liver cirrhosis.

Changes in tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) were investigated before and after hepatectomy in patients with or without liver cirrhosis (5 cases without liver cirrhosis and 14 cases with liver cirrhosis). Both the IL-6 and IL-8 values of the cirrhotic patients were significantly higher on the first postoperative day (POD) as compared with the non-cirrhotic patients. Overall, no significant correlation was found between peak values of IL-6 or IL-8 and blood loss or operating time. In the case of the cirrhotic patients, correlation of both IL-6 and IL-8 with operating time was significant at p < 0.05, gamma = 0.534 and 0.586, respectively. No correlation was found between blood loss and the peak value of IL-6, but significant correlation (gamma = 0.647, p < 0.05) was found between them in cirrhotic patients. There was no consistent increase in TNF-alpha and IL-1 beta following hepatectomy. These findings indicate that procedures undertaken to reduce the excessive production of these cytokines may be useful for preventing complications after hepatectomy in cirrhotic patients.

Carcinoma, Hepatocellular↗
PubMed1995

[Quantitative changes in cerebral blood flow of Shy-Drager syndrome induced by upright position: assessment by 99mTc-HMPAO].

We assessed orthostatic changes of cerebral blood flow (CBF) in 4 patients with Shy-Drager syndrome. Brain perfusion index (BPI) was measured by 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO). Cerebral angiography using aortic time-activity curve as an input function BPI values in supine and upright positions in Shy-Drager syndrome were compared with those in 2 cerebrovascular disease patients without orthostatic hypotension. BPI values in the upright position were significantly decreased in patients with Shy-Drager syndrome as compared with these in the supine position. No significant decrease in BPI was noted in the patients without orthostatic hypotension. These results suggest that the BPI measurement by 99mTc-HMPAO cerebral angiography is useful for the noninvasive evaluation of the orthostatic changes of the CBF.

Adult↗
PubMed1994

Kupffer cell function in chronic liver injury and after partial hepatectomy.

The reticuloendothelial system (RES) plays an important role in the biological defense system. In the liver, Kupffer cells are the main constituent of the RES, and when their function is impaired postoperative complications may more often occur. By using 99mTc-labeled human serum albumin millimicrospheres (99mTc-HSA-MM) combined with assessment of single photon emission computed tomography (SPECT), we have attempted to determine the function of Kupffer cells independently of the hepatic blood flow. First, Kupffer cell function in rats with chronic liver injury caused by CCl4 was studied. The hepatic uptake rate in chronic liver injury was decreased, and a reduced phagocytic activity of the Kupffer cells was noted. The parameter concerning Kupffer cell degradation, the excretion rate (k), was markedly decreased in the early period of chronic liver injury. Changes in Kupffer cell function after 30% and 70% hepatectomy were also studied. After 30% hepatectomy, the excretion rate was decreased on the first postoperative day (POD), and it was increased beyond that found after sham operation on the 3rd POD. In contrast, slower recovery of uptake rate was demonstrated. After 70% hepatectomy, both uptake and excretion rates were markedly reduced, and recovery was prolonged beyond the 5th POD. The hepatic uptake was not parallel with the excretion rate in either experiment. These results suggest that the method that measures the hepatic excretion rate may provide a better assessment of Kupffer cell function than the current uptake measurement with radiolabeled colloid.

Animals↗
PubMed1994

Effects of gastrectomy on motility, perfusion pressure, and caerulein-induced relaxation of sphincter of Oddi in dogs.

The effects of subtotal-gastrectomy (gastrectomy) on the spontaneous motility and caerulein-induced relaxation of the sphincter of Oddi (SO) were investigated in the dog. The spontaneous motility and the response to caerulein of the SO were recorded using perfusion method. The basal perfusion pressure (5.1 +/- 0.5 cmH2O) and the frequency of phasic contractions (6.1 +/- 0.5 cycles/min, c/min) of the SO increased to 8.2 +/- 0.6 cmH2O (p < 0.05) and 9.3 +/- 0.4c/min (p < 0.05) after gastrectomy, respectively. They were observed one month after operation (7.8 +/- 0.5 cmH2O and 9.1 +/- 0.9 c/min, p < 0.05), but did not change by vagotomy with sympathectomy (vagosympathectomy). In the spontaneous motility of the SO, the motility index increased to 143.7 +/- 18.7% (p < 0.05) at 4 hrs and 135.0 +/- 9.1% (p < 0.05) at one month after gastrectomy, but did not increase after vagosympathectomy. Caerulein had an inhibitory effect on the SO motility in the normal animal 48.0 +/- 4.2%). Gastrectomy reversed to the excitatory effect from the inhibitory effect to caerulein at 4 hrs (127.6 +/- 5.3%, p < 0.05) and at one month (126.6 +/- 5.3%, p < 0.05) after operation, but not reversed by vagosympathectomy and sham gastrectomy. The excitatory response to caerulein after gastrectomy was not effected by vagosympathectomy. It is concluded that gastrectomy induced the SO dysfunction, an increase of the perfusion pressure and the frequency of phasic contractions of the SO, and a change of the response to caerulein of the SO. These alterations suggests that one of the mechanisms of the regulation of the SO motility exist as the reflex from the stomach and/or uppermost duodenum through intrinsic nervous pathways.

Animals↗
PubMed1994

Quantitative measurement of portal blood flow by magnetic resonance phase contrast: comparative study of flow phantom and Doppler ultrasound in vivo.

A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flowmetry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow.

Adult↗
PubMed1994

Isolated pancreatectomy for ductal carcinoma of the head of the pancreas.

Hepatic carcinoma recurrence in the early months after pancreatectomy for ductal carcinoma of the head of the pancreas is one of the major factors of the poor survival rate. Early hepatic recurrence might be caused by carcinoma cells entering the portal vein as a result of surgical manipulations. To deal with this problem, we devised a new operative procedure called "isolated pancreatectomy" in 1987. This method involves no-touch pancreatic resection combined with extensive retroperitoneal skeletonization. Both the feeding and draining vessels of the pancreatic carcinoma are ligated and divided prior to pancreatectomy. The confluence of the portal vein, the superior mesenteric vein, and the splenic vein is removed together with the pancreatic head. The wide surgical field thus obtained facilitates subsequent skeletonization of the retroperitoneum. We have experienced 71 cases of pancreatectomy for ductal carcinoma of the head of the pancreas among whom isolated pancreatectomy has been performed in 16 patients since 1987. In all cases, long-term survival was obtained in the patients undergoing curative and extended resection. The cumulative five-year survival rate for stages I and II was 40.7%, and that for stage III was 17.3%. After the introduction of isolated pancreatectomy, hepatic recurrence rates within six months and 12 months after pancreatectomy have dropped to 0% and 16.7%, respectively, from the 22.9% and 31.3% of the other pancreatectomy. The survival rate for the patients with stage III in isolated pancreatectomy significantly exceeded that obtained with other pancreatectomy.

Carcinoma, Ductal, Breast↗