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Biomedical subjects

H Yamamoto

Publications and source records attributed to H Yamamoto.

At least 235 records · Page 13Linked to original sources

Differential expression of cyclooxygenase-2 (COX-2) in human bile duct epithelial cells and bile duct neoplasm.

It is well known that chronic inflammatory conditions involving the bile ducts predispose to the development of bile duct carcinoma, although the relationship between chronic inflammation and malignant transformation is unclear. In this study, by combining immunohistochemistry and computer imaging techniques, we quantified and compared the cyclooxygenase-2 (COX-2) protein expression levels of epithelial cells according with their histopathological backgrounds. This technique revealed that the highest levels of COX-2 were expressed in bile duct carcinoma cells, mainly in cytoplasm, and the expression pattern was homogenous and abundant. Moderate levels of COX-2 protein expression were also observed in noncancerous epithelial cells with inflammatory reaction, but the staining intensity was heterogeneous among the positive cells exhibiting inflammation. In contrast, only scattered weak reactivity of COX-2 protein was observed in the noncancerous bile duct epithelial cells without inflammatory reaction. Moreover, bile duct epithelial cells in primary sclerosing cholangitis (PSC) showed very strong expression of COX-2 protein, that was comparable with carcinoma cells. On the other hand, primary biliary cirrhosis (PBC) epithelial cells showed moderate levels of COX-2 expression. In addition, specific COX-2 inhibitors, JTE-522 and NS-398, directly inhibited the growth of 4 bile duct carcinoma and 1 gall bladder carcinoma cell lines that expressed COX-2 protein, in vitro. These data suggest that COX-2 expression might regulate carcinogenesis of bile duct epithelial cells in inflammatory regions and tumor progression in this cancer. The data also suggest that COX-2 selective inhibitors might have therapeutic effects not only on bile duct carcinoma, but other hepatobiliary carcinomas.

Animals↗

Congenital absence of the portal vein and role of liver transplantation in children.

BACKGROUND/PURPOSE: Congenital absence of the portal vein (CAPV) is a subtype of congenital portosystemic shunt, which can cause a broad spectrum of clinical manifestations. The authors report on 4 patients with CAPV including a boy with CAPV-associated encephalopathy, which was resolved effectively by liver transplantation (LT). METHODS: The case records of 4 pediatric patients with CAPV who were referred to the author's institution between 1984 and 1999 were reviewed. RESULTS: The patients (3 boys and 1 girl) ranged in age at diagnosis from 0.8 to 14 years. Two patients had growth retardation or disturbed consciousness, and the other 2 had no specific manifestations. Not only high serum levels of bile acids, ammonia, and transaminases but also low plasma levels of branched-chain amino acids were common laboratory findings. The absent portal vein was replaced by a large portosystemic shunt, which connected the splanchnic vein to the inferior vena cava or the left renal vein. Two patients survived without any symptoms, but 1 with growth retardation died of hepatic failure. The other with encephalopathy did not respond to medical therapy and underwent LT, which resolved symptoms and metabolic disorders effectively. CONCLUSIONS: Patients with CAPV do not always have a good prognosis. They should be followed up with careful observation of their symptoms, hepatic function, and metabolic abnormalities. LT might be indicated for patients with symptomatic CAPV unresponsive to medical therapy.

Adolescent↗

Optimal continuous positive airway pressure in patients with obstructive sleep apnoea: role of craniofacial structure.

Although nasal continuous positive airway pressure (CPAP) is effective in improving nocturnal obstructive apnoea, daytime sleepiness and well-being in patients with obstructive sleep apnoea syndrome (OSAS), not all patients tolerate this treatment. Since optimal CPAP titration is essential to maintain compliance, it is important to elucidate the factors that help to determine the optimal pressure. However, the determinants of the optimal CPAP level are controversial. The subjects comprised 27 Japanese male patients with OSAS who underwent standard polysomnography (PSG), pulmonary function tests, arterial blood gas analysis, cephalometry and CPAP titration. Twenty normal controls also underwent cephalometric analysis. The apnoea-hypopnoea index (AHI), mean oxygen saturation (mean SaO2) and the lowest SaO2 during sleep were found to be 54.7+/-22.6, 89.0+/-5.6%, and 69.7+/-9.0%, respectively by PSG. The mean optimal CPAP was 9.6+/-1.8 cmH2O. The cephalometric angles (SNA, SNB and NSBa) were similar to those found in the control subjects. but MP-H, and PNS-P were significantly longer than those in the control subjects as shown by cephalometry. The optimal CPAP was correlated with the mean SaO2 (P<0.0001), neck circumference (P<0.05) and three cephalometric variables (NSBa: P<0.01, MP-H: P<0.05, PNS-P: P<0.05). Multiple, step-wise, regression analysis showed that the mean SaO2 and NSBa were independent variables that best predicted the optimal CPAP. These variables accounted for 57.5% of the total variance (R2=0.575, P<0.001). Optimal CPAP was closely correlated with oxygen desaturation during sleep. However, the craniofacial structure had additional effects such as an independent factor in determining the optimal CPAP level.

Adult↗

Osteoid osteoma in mandibular condyle.

A 21-year-old Japanese woman presented with trismus and spontaneous pain (especially at night) around the left temporomandibular joint. Radiographic examination showed a subcortical sclerosed nodule measuring approximately 8 mm in diameter on the infero-lateral aspect of the left mandibular condyle. Amputation of the condyle was performed under general anesthesia. The patient has been in good condition 8 years postoperatively. The histopathology of the specimen consisted of actively proliferating osteoblasts mixed with an interlacing network of woven bone and osteoid trabeculae. Histopathological diagnosis was osteoid osteoma.

Adult↗

Dialysis-related amyloidosis.

Dialysis-related amyloidosis (DRA) is a well-recognized complication in patients on long-term hemodialysis. It occurs secondary to the deposition of beta(2)-microglobulin, preferentially in the musculoskeletal tissues. Plain radiography demonstrates advanced DRA findings such as bone erosions and cystic lesions, but it is not suitable for the demonstration of earlier changes. Magnetic resonance imaging and ultrasound are sufficient for the detection of amyloid deposition in the periarticular soft tissues and in the evaluation of spinal complications.

Aged↗

Relationship between interindividual differences in nicotine metabolism and CYP2A6 genetic polymorphism in humans.

BACKGROUND: Nicotine is mainly metabolized to cotinine by cytochrome P450 (CYP) 2A6. Previously, we found that the CYP2A6 gene was deleted homozygously in one subject who was deficient in cotinine formation from nicotine. OBJECTIVE: Our objective was to clarify the relationship between interindividual differences in nicotine metabolism and CYP2A6 genetic polymorphism. METHODS: Nicotine was administered to 92 healthy Japanese subjects in the form of 1 piece of nicotine gum to investigate the potency of nicotine metabolism. The cotinine-nicotine ratio of the plasma concentration 2 hours after chewing was calculated as an index of nicotine metabolism. The genotypes of CYP2A6 gene, CYP2A6*1A, CYP2A6*1B, CYP2A6*2, CYP2A6*3, CYP2A6*4, and CYP2A6*5, were determined with polymerase chain reaction-restriction fragment length polymorphism. RESULTS: A large interindividual difference in nicotine metabolism was observed. Allele frequencies of CYP2A6*1A, CYP2A6*1B, and CYP2A6*4 were 42.4%, 37.5%, and 20.1%, respectively. The CYP2A6*2, CYP2A6*3, and CYP2A6*5 alleles were not found. Three subjects genotyped as CYP2A6*4/CYP2A6*4 were completely deficient in cotinine formation. The heterozygotes of the CYP2A6*4 allele tend to show lower capacities for cotinine formation. The subjects with CYP2A6*1A/CYP2A6*1B appeared to have higher capacities of cotinine formation than subjects with CYP2A6*1A/CYP2A6*1A, although the difference was not significant. The probit plot of the cotinine-nicotine ratio was not linear; this possibly indicated the existence of a novel mutation in the CYP2A6 gene genotyped as CYP2A6*1B/CYP2A6*4. CONCLUSIONS: The relationship between interindividual differences in nicotine metabolism and CYP2A6 genetic polymorphism in humans was proved.

Administration, Oral↗

Total enteroscopy with a nonsurgical steerable double-balloon method.

BACKGROUND: Deep insertion of an enteroscope by use of a push technique is difficult. A new method of enteroscopy was developed, a double-balloon method, to improve the access to the small intestine. METHODS: The new method uses 2 balloons, one attached to the tip of the endoscope and another at the distal end of an overtube. By using these balloons to grip the intestinal wall, the endoscope can be inserted further without forming redundant loops in the small intestine. This method was tried with a standard upper endoscope in 3 patients and with a longer enteroscope in 1 patient. RESULTS: Despite its short length the upper endoscope was successfully inserted as far as 30 to 50 cm beyond the ligament of Treitz in the 3 patients. In the fourth patient the longer enteroscope was successfully inserted beyond the ileo-cecal valve. CONCLUSIONS: The double-balloon method facilitates endoscopic access to the small intestine.

Adolescent↗

Successful en bloc resection of a large superficial gastric cancer by using sodium hyaluronate and electrocautery incision forceps.

BACKGROUND: The advisability of endoscopic mucosal resection (EMR) for treatment of large superficial gastric cancers has been challenged. For more reliable en bloc resection, a new method of EMR was developed that uses a viscous substance, sodium hyaluronate, and two newly designed devices. METHODS: A large superficial gastric cancer was treated with this new EMR technique. Sodium hyaluronate was injected into the submucosa and mucosal incisions were made with a needle-knife. The newly developed incision forceps and flat-ended transparent hood were used for submucosal incisions. RESULTS: The large cancer was successfully resected endoscopically as a single piece of mucosa 6 cm in diameter without complication. Histopathologic evaluation of the specimen confirmed that the resection was curative. CONCLUSIONS: EMR with sodium hyaluronate along with two new devices may be a reliable method for en bloc resection of large superficial gastric lesions.

Aged↗

Effect of FR167653 on pancreatic ischemia-reperfusion injury in dogs.

BACKGROUND: The role of inflammatory cytokines is still unclear in ischemia-reperfusion injury of the pancreas. We investigated the effect of FR167653 (FR), a newly developed compound that is a potent suppressor of interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha on ischemia-reperfusion injury of the isolated pancreatic tail in dogs. METHODS: The tail of the pancreas was subjected to ischemia for 90 minutes. During occlusion of the vascular inflow, the head of the pancreas was removed. A control group (n = 14) and an FR treatment group (n = 11) were evaluated for survival rate, tissue blood flow, arterial oxygen pressure (Pao(2)), serum amylase and lipase levels, glucose and insulin, liver enzymes, creatinine, IL-1beta mRNA in the peripheral blood, and histopathology. RESULTS: Six of the 14 control animals and 2 of the 11 FR-treated animals died. The FR treatment group showed lower amylase (P=.037) and lipase (P =.030) levels, lower IL-1beta mRNA expression (P =.033), and less pancreatic tissue damage (P =.041) than did the control group, but there was no remarkable change in endocrine function (P =.422). Pao(2) during the acute phase in the FR treatment group was maintained (P=.009), but pulmonary tissue was damaged. Results of biochemical and histologic examinations of the liver and kidneys were unremarkable. CONCLUSIONS: FR ameliorates ischemia-reperfusion injury of the pancreas and reduces the production of inflammatory cytokines that may contribute to secondary damage to distant organs.

Animals↗

Hepatocellular carcinoma with biliary tumor thrombi: aggressive operative approach after appropriate preoperative management.

BACKGROUND: The aim of this study was to clarify clinicopathologic characteristics of, and to evaluate an aggressive treatment strategy for, hepatocellular carcinoma with biliary tumor thrombi. METHODS: From 1980 to 1999, a total of 132 patients underwent hepatectomy for hepatocellular carcinoma. Of these, 17 patients had macroscopic biliary tumor thrombi and were retrospectively analyzed. RESULTS: The operative procedures included right hepatic trisegmentectomy (n = 1), right or left hepatic lobectomy (n = 11), and segmentectomy or subsegmentectomy (n = 5). In 13 patients, tumor thrombi extended beyond the hepatic confluence and was treated by thrombectomy through a choledochotomy in 8 patients and extrahepatic bile duct resection and reconstruction in 5 patients. The 3- and 5-year survival rates were 47% and 28%, respectively, with a median survival time of 2.3 years. These survival rates were similar to those achieved in 115 patients without biliary tumor thrombi. In a multivariate analysis, expansive growth type and solitary tumors were independent prognostic variables for favorable outcome after operation, whereas biliary tumor thrombi was not a significant prognostic factor. CONCLUSIONS: Surgery after appropriate preoperative management of hepatocellular carcinoma with biliary tumor thrombi yields results similar to those of patients without biliary involvement. Hepatectomy with thrombectomy through a choledochotomy appears to be as effective as a resection procedure.

Bile Duct Neoplasms↗

Flexion of the knee increases the distance between the popliteal artery and the proximal tibia: MRI measurements in 15 volunteers.

We determined which angle of flexion best prevents popliteal artery injury during knee surgery. We took MRIs of the knee in the lateral position with the knee in 0 degrees, 45 degrees, 90 degrees, and 120 degrees of flexion in 15 volunteers. The shortest distance between the posterior cortex of the tibia and the popliteal artery was measured at various levels from the knee joint to 60 mm distally. At the level of the joint and 15 mm distally, the distance between the tibia and artery increased with increasing knee flexion. More distally, no significant difference was noted with increasing flexion. Flexion of the knee may minimize injury to the popliteal artery in procedures between the level of the joint and 15 mm distal to the joint.

Adult↗

The antioxidant effect of DL-alpha-lipoic acid on copper-induced acute hepatitis in Long-Evans Cinnamon (LEC) rats.

The Long-Evans Cinnamon (LEC) rats, due to a genetic defect, accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson's disease and spontaneously develop acute hepatitis with severe jaundice. In this study we examined the protective effect of DL-alpha-Lipoic acid (LA) against acute hepatitis in LEC rats. LA was administered to LEC rats by gavage in doses of 10, 30 and 100 mg/kg five times per week, starting at 8-weeks-old and continuing till 12-weeks-old. Although LA had little effect against the increases in serum transaminase activities, it suppressed the loss of body weight and prevented severe jaundice in a dose-dependent manner. Antioxidant system analyses in liver showed that LA treatment significantly suppressed the inactivations of catalase and glutathione peroxidase, and the induction of heme oxygenase-1, an enzyme which is inducible under oxidative stress. Furthermore, LA showed dose-dependent suppressive effect against increase in nonheme iron contents of both cytosolic and crude mitochondrial fractions in a dose-dependent manner. Although at the highest dose, LA slightly suppressed the accumulation of Cu in crude mitochondrial fraction, it had no effect on the accumulation of Cu in cytosolic fraction. While LA completely suppressed the increase in lipid peroxidation (LPO) in the microsomal fraction at the highest dose, the suppressive effect against LPO in crude mitochondrial fractions was slight. From these results, it is concluded that LA has antioxidant effects at the molecular level against the development of Cu-induced hepatitis in LEC rats. Moreover, mitochondrial oxidative damage might be involved in the development of acute hepatitis in LEC rats.

Acute Disease↗

Maternal serum levels of type I and type III procollagen peptides in pre-eclamptic pregnancy.

OBJECTIVE: To compare maternal serum levels of two markers of collagen synthesis, procollagen I carboxy-terminal peptide (PICP) and procollagen III amino-terminal peptide (PIIINP), in patients with pre-eclampsia and in controls. METHODS: PICP and PIIINP were measured by radioimmunoassay in maternal serum samples from patients diagnosed with pre-eclampsia at 32 weeks' gestation or later and in controls from the same period of gestation. For PICP, 37 cases and 36 controls were studied; for PIIINP, 12 cases and 19 controls were studied. RESULTS: Both PICP and PIIINP levels were significantly elevated in patients with pre-eclampsia. PICP and PIIINP levels were, on average, 20% and 80% higher than in controls, respectively. CONCLUSIONS: These results are in agreement with previous findings that maternal serum levels of PICP and PIIINP are mildly elevated in patients with pre-eclampsia. These markers are unlikely to be useful in the prediction of pre-eclampsia.

Case-Control Studies↗

Chemopreventive effects of ONO-8711, a selective prostaglandin E receptor EP(1) antagonist, on breast cancer development.

Levels of prostaglandin E(2) (PGE(2)) in human and rodent breast cancers are higher than surrounding normal tissues. PGE(2) exhibits biological activity through binding to membrane receptors, EP(1-4). The present study was designed to investigate the effects of ONO-8711, a newly synthesized selective PGE receptor EP(1) antagonist, on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced breast cancer development. Starting at 7 weeks of age, female Sprague-Dawley (SD) rats were given PhIP (85 mg/kg body weight) by gavage four times weekly for two weeks. Dietary administration of ONO-8711 at 400 or 800 p.p.m. delayed occurrence of breast tumors for 2 or 4 weeks, respectively. At 20 weeks after the last dosing of PhIP, all animals were killed and complete autopsy was made. All breast tumors were diagnosed as invasive ductal adenocarcinomas histopathologically. Administration of ONO-8711 at 800 p.p.m. significantly decreased PhIP-induced breast cancer incidence, multiplicity and volume compared with those of rats fed the control diet (56% versus 79%, P < 0.05, 1.2 versus 2.5, P < 0.05, 0.7 versus 1.4 cm(3), P < 0.01, respectively). Apoptosis was significantly increased in breast cancer cells by feeding of ONO-8711 at 800 p.p.m. of 158% (P < 0.05). EP(1) receptor was detected by reverse transcription-polymerase chain reaction (RT-PCR) in breast cancers, not in normal tissues. These results suggest that EP(1) receptor is associated with breast cancer development and selective PGE receptor EP(1) antagonists may possess chemopreventive effects through the induction of apoptosis without any side effects.

Animals↗

Association of matrilysin mRNA expression with K-ras mutations and progression in pancreatic ductal adenocarcinomas.

The matrix metalloproteinase matrilysin has been implicated in the progression of gastrointestinal and other cancers. The aim of this study was to examine matrilysin mRNA expression and determine whether it is correlated with K-ras mutations and/or progression of pancreatic carcinoma. Using the semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we analyzed 11 pancreatic cancer cell lines and 70 pancreatic adenocarcinoma tissues for matrilysin mRNA expression. The results were correlated with clinicopathological characteristics and K-ras mutations. Significant amounts of matrilysin mRNA were detected in six of the eight cell lines with K-ras mutations but not in the three cell lines with wild-type K-ras. Matrilysin mRNA was detected in 57 (81.4% ) of the 70 tumor tissues and in all of the eight liver metastases, but not in any of the adjacent non-tumorous tissues. Matrilysin expression was significantly correlated with the size of tumor, tumor spreading, lymph node metastasis, advanced pathologic tumor-node- metastasis stage and K-ras mutations. The relative amounts of matrilysin mRNA in tumor tissues increased with increase in tumor stage and were highest in liver metastatic tumor tissues. Our results suggest that matrilysin, the expression of which is correlated with K-ras mutations, plays a key role in tumor growth and progression of pancreatic carcinoma.

Adenocarcinoma↗

Development of a sub-eV resolution soft-X-ray spectrometer for a transmission electron microscope.

We constructed a grazing-incidence soft-X-ray spectrometer for a transmission electron microscope. The spectrometer, which was composed of a grating and a CCD detector, was attached to a JEM2000FX transmission electron microscope. B K-emission spectra of hexagonal boron-nitride, which give the density of states of the valence band of the material, were obtained with an energy resolution of about 0.6 eV.

Letter↗

Involvement of annexin V in the antiproliferative effect of GnRH agonist on cultured human uterine leiomyoma cells.

The objective of this study was to elucidate the role of annexin V, an endogenous inhibitor of protein kinase C (PKC), with regard to the antiproliferative effect of gonadotrophin-releasing hormone (GnRH) agonist (buserelin) on cultured human uterine leiomyoma cells. Uterine leiomyoma tissue was collected from the surgical specimens of patients and cells from 37 specimens (15 cases) were cultured. For up to 96 h after the addition of buserelin to the cultured cells, a time-dependent antiproliferative effect was noted in the group to which 10(-5) mol/l buserelin was added. Both the intracellular concentration of annexin V and the expression of annexin V mRNA increased time-dependently with the addition of buserelin. The intracellular concentration of annexin V increased with the addition of PKC activator (12-O:-tetradecanoylphorbor-13-acetate; TPA) much as it did with the addition of buserelin, and the rise in the concentration caused by the addition of buserelin was completely attenuated by pretreatment with PKC inhibitor (calphostin C). Our findings suggest that buserelin inhibits cell proliferation in cultured human uterine leiomyoma cells accompanied with an increase in the intracellular concentration of annexin V, mediated, at least in part, by the activation of PKC.

Annexin A5↗