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Biomedical subjects

T Asano

Publications and source records attributed to T Asano.

At least 181 records · Page 10Linked to original sources
PubMed1999

Normalization of glucose entry under the high glucose condition by phlorizin attenuates the high glucose-induced morphological and functional changes of cultured bovine retinal pericytes.

We previously reported that sodium-dependent glucose uptake is present in bovine retinal pericytes and that phlorizin normalizes its glucose consumption under high glucose conditions. To clarify the effect of phlorizin on morphological and functional change of retinal pericytes under high glucose conditions, retinal pericytes were incubated in media with 5 mM glucose, 30 mM glucose, and 30 mM glucose plus 0.2 mM phlorizin for 7 days. The diameter of cells in the concentrations of glucose more than 10 mM were significantly larger than those in 5 mM glucose and 30 mM glucose plus phlorizin. Glucose, sorbitol and fructose contents of the cells in 30 mM glucose were significantly increased compared with those in 5 mM glucose, and were normalized by phlorizin. Thymidine uptake in the concentrations of glucose more than 20 mM was significantly decreased compared with that in 5 mM glucose. Myoinositol uptake, and DNA in 30 mM glucose were significantly reduced, and were normalized with phlorizin. Myoinositol content in 30 mM glucose was the same as that in 5 mM glucose, but was significantly decreased by phlorizin. The ratios of glucose to sorbitol or fructose in 30 mM glucose were significantly decreased, compared with those in 5 mM glucose and 30 mM glucose plus phlorizin. Therefore, the cellular enlargement and decreased DNA synthesis in cultured bovine retinal pericytes with abnormal glucose metabolism under high glucose conditions are attenuated by phlorizin, independent of the cellular myoinositol content.

Animals↗
PubMed1999

Secretory low-molecular-weight phospholipases A2 and their specific receptor in bile ducts of patients with intrahepatic calculi: factors of chronic proliferative cholangitis.

Intrahepatic calculi is characterized by an intractable course and frequent recurrences, requiring multiple operative interventions. Chronic proliferative cholangitis, an active and long-standing inflammation of the stone-containing bile ducts with the hyperplasia of epithelia and the proliferation of the duct-associated mucus glands, may underlie the complex nature of the disease. In terms of the pathophysiology, interest has been focused on the role of secretory low-molecular-weight phospholipases A2 (sPLA2s) as inflammatory mediators or factors modulating cell functions via their specific sPLA2-receptor, and also on the production and secretion of altered mucin molecules from the inflamed bile ducts. In search of factors involving chronic proliferative cholangitis, the sPLA2 isoforms in the bile such as the pancreatic-type sPLA2 (group IB sPLA2) and the arthritic-type sPLA2 (group IIA sPLA2), were assayed to correlate protein masses of the sPLA2s with alterations in biliary composition. Furthermore, the steady-state messenger RNA (mRNA) levels of the sPLA2s, the membrane-bound sPLA2-receptor, cystic fibrosis transmembrane conductance regulator (CFTR), and mucin core polypeptide (MUC) genes in the bile ducts were assayed by reverse- transcriptase polymerase chain reaction (RT-PCR). Immunoreactive sPLA2-IB and sPLA2-IIA levels were significantly higher in the bile from the stone-containing hepatic ducts (2315 +/- 677 for sPLA2-IB; 281 +/- 42 for sPLA2-IIA ng/dL, mean +/- SEM; n = 20) than in the ductal bile from gallbladder stone patients (609 +/- 92, P <.01; 22 +/- 2, P <.01; n = 24). The increased sPLA2 levels were associated with a concomitant increase in lysophosphatidylcholine, prostaglandin E2 (PGE2), and total mucin concentrations. The affected bile ducts showed an increased mRNA level of sPLA2-IB and sPLA2-IIA compared with the ducts from control subjects, in whom the mRNAs of the sPLA2-receptor and other sPLA2 isoforms, such as groups V and X sPLA2s, were coincidently expressed. Reflecting the increased amounts of total biliary mucins, the affected ducts showed an increase in mRNA levels of CFTR as well as MUC2, MUC3, MUC5AC, MUC5B, and MUC6 compared with the ducts from control subjects. In intrahepatic calculi, an enhanced expression of the sPLA2s and their possible cross-talk via sPLA2-receptor may be of pathophysiological significance for the chronic proliferative cholangitis, in association with the enhanced CFTR expression and the alterations in mucin gene expression in the bile ducts, probably through potentiating arachidonate metabolism with associated biliary alterations favoring growth of preexisting stones and even further progressions.

Bile↗
PubMed1999

Suppression of sodium-dependent glucose uptake by captopril improves high-glucose-induced morphological and functional changes of cultured bovine retinal pericytes.

The effects of captopril on glucose uptake, as well as morphological and functional changes of retinal pericytes, in a high-glucose medium were examined. Retinal pericytes were incubated in medium with 5 and 30 mM glucose and 30 mM glucose with 10(-6) to 10(-3) M captopril. Captopril decreased the cellular uptakes of d-glucose and alpha-methyl glucoside in the presence, but not in the absence, of sodium. The cellular size and contents of glucose, sorbitol, and fructose were increased in 30 mM glucose concomitant with the decreased thymidine, cellular DNA content, and ratios in glucose to sorbitol and to fructose, compared with those in 5 mM glucose. These changes observed in 30 mM glucose were reversed by 10(-4) M captopril. These data suggest that the suppression of d-glucose uptake through a sodium-coupled glucose transporter by captopril may attenuate the swelling and loss of pericytes observed in the early stage of diabetic retinopathy.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Trigeminal ganglioneuroma.

We present the case of an 8-year-old girl with a ganglioneuroma in the left cerebellopontine angle region. The tumor originated from the sensory root of the trigeminal nerve. Histopathologically, it was composed of neoplastic ganglion cells and Schwann cells, leading us to the diagnosis of ganglioneuroma. Intracranial ganglioneuroma is very rare. To our knowledge, this is the first report of a trigeminal ganglioneuroma. The nature and origin of this tumor are discussed and the literature reviewed.

Cerebellopontine Angle↗
PubMed1999

Recurrent hepatocellular carcinoma successfully treated with radiofrequency thermal ablation.

We report a patient with hepatocellular carcinoma (HCC) who was successfully treated with radiofrequency thermal ablation (RFA). A 71-year-old man was admitted to our hospital in August 1996 with recurrence of HCC. Partial hepatic resection had been performed in January 1993 for HCC that had measured 1.3 cm in segment VIII, and subsequently he had received six sessions of percutaneous ethanol injection (PEI) for treatment of recurrence. Dynamic computed tomography (CT) performed in August 1996 showed two recurrent tumors, one measuring 3.8 cm in segment VIII adjacent to the right hepatic vein, and one measuring 2.0 cm in segment V. Three sessions of percutaneous RFA were performed. After this treatment, most of the tumor in segment VIII and all the tumor in segment V showed low density on dynamic CT, and the right hepatic vein was preserved. However, a remnant of the mass appeared near the right hepatic vein 2 months after the treatment. An additional two sessions of RFA were performed. After the end of treatment, serum alpha-fetoprotein level dropped to the normal range, and no sign of recurrence has been observed until September 1998.

Aged↗
PubMed1999

Intraductal papillary mucinous tumors of the pancreas.

BACKGROUND: An increasing number of intraductal papillary mucinous tumors of the pancreas have been reported in recent years. The indolent character and favorable prognosis of this neoplasm have been described. METHODS: Intraductal papillary mucinous tumors were classified into main duct type (n = 8) and branch type (n = 28) according to the dominant location of the tumor. This single-institute study examined the clinicopathological features and outcome after surgical resection in patients with intraductal papillary mucinous tumors. RESULTS: The gender, age, tumor size, and prognosis were quite similar for the main duct type and branch type groups. Branch type tumors were more frequently located in the head of the pancreas than were main duct type tumors. Histological examination revealed that 88% of main duct type tumors were adenocarcinomas; however, only 46% of branch type tumors were adenocarcinomas. Five-year survival rates for the patients with all main duct type tumors (n = 8), main duct type adenocarcinoma (n = 7), all branch type tumors (n = 28), and branch duct adenocarcinoma (n = 13) were 100%, 100%, 90.6%, and 90.9%, respectively. CONCLUSIONS: Intraductal papillary mucinous tumors had a favorable prognosis after surgical treatment. A curative pancreatectomy should be indicated for this localized malignant tumor.

Adult↗
PubMed1999

Rho-kinase-mediated pathway induces enhanced myosin light chain phosphorylations in a swine model of coronary artery spasm.

OBJECTIVE: We recently demonstrated in our swine model of coronary artery spasm that enhanced myosin light chain (MLC) phosphorylations (both MLC mono- and diphosphorylations) play a central role in the pathogenesis of the spasm. However, the molecular mechanism for and the phosphorylation sites for the enhanced MLC phosphorylations were unknown. In the present study, we addressed these points using hydroxyfasudil, a novel inhibitor of protein kinases, which we found preferentially inhibits Rho-kinase. METHODS: The specificity of the inhibitory effects of hydroxyfasudil on Rho-kinase, MLCK, MRCK beta and PKC were examined by kinase assay in vitro. The left porcine coronary artery was chronically treated with interleukin-1 beta (IL-1 beta, 2.5 micrograms). Two weeks after the operation, coronary artery vasomotion was examined both in vivo and in vitro. MLC phosphorylations were examined by Western blot analysis and the sites for the phosphorylations by anti-phosphorylated MLC antibodies that identified the monophosphorylation site as Ser19 and diphophorylation sites as Ser19/Thr18 of MLC. RESULTS: Inhibitory effects of hydroxyfasudil was at least 100 times more potent for Rho-kinase as compared with other protein kinases tested. Intracoronary serotonin (10 micrograms/kg) caused coronary hyperconstriction at the IL-1 beta-treated site in vivo, which was dose-dependently inhibited by hydroxyfasudil (p < 0.01). The coronary segment taken from the spastic site also showed hypercontractions to serotonin in vitro, which were again dose-dependently inhibited by hydroxyfasudil (p < 0.01). Western blot analysis showed that MLC monophosphorylation was significantly greater in the spastic segment than in the control segment, while MLC diphosphorylation was noted only at the spastic segment (p < 0.01). The sites for the mono- and diphosphorylated MLC were identified as the monophosphorylated site Ser19 and diphosphorylated sites Ser19/Thr18 of MLC, respectively. Both types of MLC phosphorylations at the spastic segment were markedly inhibited by hydroxyfasudil (p < 0.01). CONCLUSION: These results indicate that hydroxyfasudil-sensitive Rho-kinase-mediated pathway appears to mediate the enhanced MLC phosphorylations (on Ser19 and Ser19/Thr18 residues) and plays a central role in the pathogenesis of coronary artery spasm.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Imidapril, an angiotensin-converting enzyme inhibitor, improves insulin sensitivity by enhancing signal transduction via insulin receptor substrate proteins and improving vascular resistance in the Zucker fatty rat.

Angiotensin-converting enzyme (ACE) inhibitors are antihypertensive agents, that inhibit the conversion of angiotensin I to angiotensin II, resulting in smooth-muscle relaxation and a reduction of vascular resistance. Recently, it has been suggested that ACE inhibitors improve insulin resistance in diabetic patients. To investigate the effect of an ACE inhibitor on insulin sensitivity, insulin signaling, and circulation, imidapril was administered orally or intraduodenally to Zucker fatty rats. Oral administration of imidapril improved insulin sensitivity based on the results of an oral glucose tolerance test (OGTT) and a decrease in urinary glucose secretion. Phosphatidylinositol 3-kinase (PI 3-kinase) activity associated with hepatic insulin receptor substrate-1 (IRS-1) in the insulin-stimulated condition was significantly enhanced 110% without a significant alteration in tyrosine phosphorylation of IRS-1 in the imidapril-treated group. In muscle, IRS-1 tyrosine phosphorylation and PI 3-kinase activity associated with IRS-1 in the insulin-stimulated condition were enhanced 70% and 20%, respectively, in the imidapril-treated group. In contrast, an alteration of the IRS-2 pathway was observed only in liver; a significant insulin-induced increase in the IRS-2-associated PI 3-kinase over the basal level was observed in the imidapril-treated group but not in the control. In addition, treatment with imidapril was shown to significantly reduce blood pressure and increase blood flow in the liver and muscle. These results suggest that the ACE inhibitor imidapril may improve insulin sensitivity not only by acting directly on the insulin signaling pathway but also by increasing blood flow in tissues via normalization of vascular resistance, a major cause of hypertension.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Risk of bile duct carcinogenesis after excision of extrahepatic bile ducts in pancreaticobiliary maljunction.

BACKGROUND: A reflux of pancreatic juice into the biliary tract caused by pancreaticobiliary maljunction (PBM) has been considered important in the development of biliary tract carcinogenesis in choledochal cysts. We excised extrahepatic bile ducts in patients with choledochal cysts to terminate the reflux of pancreatic juice. We investigated whether this surgery could stop the development of the residual bile duct carcinoma. METHODS: Fifty-six patients with a diagnosis of PBM with choledochal dilatation underwent surgical excision of extrahepatic bile ducts. We applied a person-year method to compare the relative risks (observed number/expected number) of biliary tract carcinoma before and after surgery. RESULTS: In 3 patients, bile duct carcinoma developed in residual dilated segments 19 years 6 months, 8 years 8 months, and 2 years 5 months, respectively, after surgery. Although the relative risk in the post-surgery group was slightly decreased by surgery, it was still high compared with that of the general population. CONCLUSIONS: The incidence of bile duct carcinoma is still high, even after excision of extrahepatic bile ducts in PBM patients with choledochal dilatation. For these patients, careful long-term follow-up is necessary, especially after operations that leave the dilated bile ducts, such as cases of Todani's type IV-A.

Adolescent↗
PubMed1999

Transcranial approach for transsphenoidal encephalocele: report of two cases.

BACKGROUND: Whereas the transcranial approach has been regarded as the therapy of choice for transethmoidal encephalocele, its feasibility for transsphenoidal encephalocele has remained controversial, particularly in neonates and infants. CASE REPORT: Two cases of transsphenoidal encephalocele operated transcranially are presented. In the first case, this 6-year-old boy underwent a transpalatal operation with repair of a cleft palate in another hospital before admission. Reoperation via the transcranial route was carried out because of postoperative recurrent meningitis. With partial resection of the anterior wall, the encephalocele could be separated from the underlying tissue, and the interspace was filled with the pericranial flap. He made an uneventful recovery and has been well for the past 3 years. The second was a 3-month-old baby with a large encephalocele filling the nasopharyngeal space. As the cleft palate was absent, the transcranial approach was employed. In this case, the herniated tissue was excised at the lowest level possible. Postoperatively, panhypopituitarism became manifest. Re-evaluation of the preoperative magnetic resonance imaging (MRI) disclosed a small mass far below the dorsum sellae, which turned out to be an anomalous pituitary gland on histologic examination. CONCLUSIONS: The transcranial approach is considered a valid alternative for the therapy of transsphenoidal encephalocele, particularly when the transpalatal approach is unfeasible. While the anterior wall of the herniated sac may be safely resected, the posterior wall should under no circumstances be sacrificed. The preoperative MRI is essential, as it may provide valuable information as to the location of vital structures within the herniated tissue.

Child↗
PubMed1999

Effect of NAD+-dependent isocitrate dehydrogenase gene (IDH1, IDH2) disruption of sake yeast on organic acid composition in sake mash.

The ratio of organic acids in sake mash is a very important factor affecting the taste of alcoholic beverages. To alter the organic acid composition in sake and investigate the mechanism of producing organic acids in sake mash, we examined the effect of NAD+-dependent isocitrate dehydrogenase (IDH) activity deficiency in sake yeast by disrupting the IDH1 or IDH2 gene. Two haploid strains (MATa or MATa genotype) isolated from sake yeast Kyokai no. 701 (K701) were disrupted using the aureobasidin A resistant gene (AUR1-C) as a selection marker. These disruptants were defective in the activity of IDH and failed to grow on medium containing glycerol as a sole carbon source. Sake meter, alcohol concentration, and glucose consumption in sake brewed with the disruptants were reduced in comparison with those of the parental strains. The production of citrate (including isocitrate), malate, and acetate by the disruptants was increased, but succinate production was reduced to approximately half in comparison with the parental strains. These results indicate that approximately half the amount of succinate in sake mash is produced via the oxidative pathway of the TCA cycle in sake yeast. While the diploid strain constructed by mating haploid disruptants for the IDH gene exhibited stronger fermentation ability than the haploid disruptants, almost similar profiles of components in sake were obtained for both strains.

Journal Article↗
PubMed1999

Improvement of isoamyl acetate productivity in sake yeast by isolating mutants resistant to econazole.

Sake yeast strains were improved so as to produce larger amounts of isoamyl acetate than the parental strain by isolating econazole-resistant mutants. Econazole, an imidazole antimycotic, directly interacts with unsaturated fatty acids in the yeast cell membrane, where it also inhibits the synthesis of ergosterol and decreases the ratio of unsaturated to saturated fatty acids. In contrast, alcohol acetyltransferase (AATase), which catalyzes the synthesis of isoamyl acetate, is inhibited by unsaturated fatty acids. Fifty econazole-resistant mutants were isolated from a sake yeast, Kyokai no. 701, several of which produced approximately 1.4 to 2.4 times more isoamyl acetate and an almost equal amount of isoamyl alcohol compared with the parental strain. The AATase activities of the mutants in koji extract were 1.2 to 1.4 times higher, and the unsaturated to saturated fatty acid ratios were lower, than in the parental strain.

Journal Article↗
PubMed1999

Triterpene saponins and lignans from the roots of Pulsatilla chinensis and their cytotoxic activity against HL-60 cells.

Two new triterpene saponins (8 and 9) and seven previously reported triterpene saponins (1-7) based upon oleanolic acid or hederagenin, along with two known lignans, (+)-pinoresinol (10) and beta-peltatin (11), were isolated from a saponin fraction prepared from the MeOH extract of the roots of Pulsatilla chinensis. The structures of the new saponins were determined by spectroscopic analysis, including 2D NMR spectroscopic techniques, and the results of hydrolytic cleavage. The isolated compounds and some derivatives were evaluated for their cytotoxic activity against HL-60 human leukemia cells.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Antioxidant therapy against cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

1. Approximately one-third of the morbidity and mortality due to aneurysmal subarachnoid hemorrhage (SAH) is caused by delayed ischemic neurological deficit (DIND) due to cerebral vasospasm. 2. Compared to prolonged arterial constriction in other parts of the body, cerebral vasospasm is characterized by its long duration and refractoriness to vasodilators such as calcium antagonists. 3. Whereas oxyhemoglobin (oxyHb) liberated into the CSF from the subarachnoid clot has been deemed the causative agent of vasoconstriction, the biochemical mechanisms whereby oxyHb elicits prolonged constriction of the cerebral arteries has remained elusive. Here, we suggest that oxyHb triggers the generation of reactive oxygen intermediates (ROI) within the CSF. 4. Multiple lines of evidence indicate that the occurrence of vasospasm, namely, prolonged smooth muscle contraction, is due to the following intracellular events. 5. First, hydroxyl radicals (OH*), the most reactive species of ROI, are generated within the cerebral arterial wall via the Fenton and Haber-Weiss reactions catalyzed by oxyHb. Second, subsequent peroxidative membrane damage in the arterial smooth muscle cell enhances the metabolism of phosphatidylcholine and phosphatidylethanolamine, leading to a rise in the intracellular level of diacylglycerol, an endogenous activator of protein kinase C. 6. The prolonged arterial contraction that occurs during vasospasm is attributable primarily to the activation of protein kinase C, not to the Ca2+/calmodulin system. In this article, literature relevant to the above thesis is reviewed, and the rationale for the antioxidant therapy against cerebral vasospasm is discussed.

Animals↗
PubMed1999

Role of nitric oxide in pathogenesis underlying ischemic cerebral damage.

1. Based upon the intriguing report that nitric oxide synthase (NOS) inhibitor dose-dependently reverses N-methyl-D-aspartate (NMDA)-induced neurotoxicity observed in primary cortical cell cultures, many laboratories have investigated whether NOS inhibition is beneficial as a treatment for cerebral ischemia. 2. Although the results are variable, it is likely thought that nitric oxide plays a key role in pathomechanism underlying ischemic brain damage. 3. We review the experimental studies on effects of NOS inhibition on cerebral ischemia and measuring nitric oxide produced in the brain subjected to cerebral ischemia. 4. Finally, the possibility of NOS inhibitors as a therapeutical tool is discussed.

Animals↗
PubMed1999

Increased insulin sensitivity and hypoglycaemia in mice lacking the p85 alpha subunit of phosphoinositide 3-kinase.

The hallmark of type 2 diabetes, the most common metabolic disorder, is a defect in insulin-stimulated glucose transport in peripheral tissues. Although a role for phosphoinositide-3-kinase (PI3K) activity in insulin-stimulated glucose transport and glucose transporter isoform 4 (Glut4) translocation has been suggested in vitro, its role in vivo and the molecular link between activation of PI3K and translocation has not yet been elucidated. To determine the role of PI3K in glucose homeostasis, we generated mice with a targeted disruption of the gene encoding the p85alpha regulatory subunit of PI3K (Pik3r1; refs 3-5). Pik3r1-/- mice showed increased insulin sensitivity and hypoglycaemia due to increased glucose transport in skeletal muscle and adipocytes. Insulin-stimulated PI3K activity associated with insulin receptor substrates (IRSs) was mediated via full-length p85 alpha in wild-type mice, but via the p50 alpha alternative splicing isoform of the same gene in Pik3r1-/- mice. This isoform switch was associated with an increase in insulin-induced generation of phosphatidylinositol(3,4,5)triphosphate (PtdIns(3,4,5)P3) in Pik3r1-/- adipocytes and facilitation of Glut4 translocation from the low-density microsome (LDM) fraction to the plasma membrane (PM). This mechanism seems to be responsible for the phenotype of Pik3r1-/- mice, namely increased glucose transport and hypoglycaemia. Our work provides the first direct evidence that PI3K and its regulatory subunit have a role in glucose homeostasis in vivo.

Animals↗
PubMed1999

Posture correction as part of behavioural therapy in treatment of myofascial pain with limited opening.

In this study, we applied cognitive behavioural intervention to subjects who had painful limited mouth opening, with or without posture correction in daily life. The efficacy of non-intervention control was then compared with it in order to study the effectiveness of posture correction as part of a biobehavioural therapy. The visual analogue scale (VAS) value of pain intensity at maximum mouth opening and disturbance in daily life sharply declined in the group which received only cognitive behavioural intervention and those who received it together with posture correction in daily life compared to the non-intervention control group although there was little difference between the intervention groups. Moreover, pain-free unassisted mouth opening was restored earlier in the group which had added posture correction. This suggests that posture correction in daily life has a positive effect in alleviating myofascial pain with limited mouth opening.

Adult↗