Biomedical subjects

Sachiko Tanaka

Publications and source records attributed to Sachiko Tanaka.

12 recordsLinked to original sources

PubMed2003

Enhanced binding of nor-binaltorphimine to kappa-opioid receptors in rats dependent on butorphanol.

Autoradiographic characterization of binding for brain kappa(1) ([(3)H]CI-977) and kappa(2) ([(3)H]bremazocine) in the presence of DAMGO ([D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin), DPDPE ([D-Pen(2), D-Pen(5)]-enkephalin), and U-69,593 opioid receptors, in the presence of different concentrations of a selective unlabeled kappa-opioid receptor antagonist, nor-binaltorphimine (nor-BNI), was performed in rats in which dependence on or withdrawal from butorphanol had been established. Dependence was induced by a 72 hr intracerebroventricular (i.c.v.) infusion with butorphanol (26 nmol/microl/hr; butorphanol dependent). Butorphanol withdrawal was produced by terminating the infusion of butorphanol in dependent animals. Responses were studied 7 hr following termination (butorphanol withdrawal). IC(50) values from competition studies were estimated by fitting inhibition curves for both kappa(1)- and kappa(2)-opioid receptor assays. In both dependent and withdrawal groups, the IC(50) values obtained against [(3)H]CI-977 or [(3)H]bremazocine with nor-BNI were decreased (ratios of approximately 0.03-0.21 and approximately 0.05-0.42 vs. control, respectively) in brain regions, including frontal cortex, nucleus accumbens, claustrum, dorsal endopiriform nucleus, caudate putamen, parietal cortex, posterior basolateral amygdaloid nucleus, dorsomedial hypothalamus, hippocampus, posterior paraventricular thalamic nucleus, periaqueductal gray, substantia nigra, superficial gray layer of the superior colliculus, ventral tegmental area, and locus coeruleus, compared with control. These results indicate that, in butorphanol-dependent and butorphanol-withdrawal rats, the brain kappa(1)- and kappa(2)-opioid receptors developed a supersensitivity to antagonist binding.

Animals↗

PubMed2003

Atypical protein kinase C mediates activation of NF-E2-related factor 2 in response to oxidative stress.

Transcription factor NF-E2-related factor 2 (Nrf2) regulates the induction of antioxidative proteins, including heme oxygenase-1 (HO-1). Nrf2 is sequestered in the cytoplasm by Keap1 under unstimulated conditions but translocates into the nucleus and transactivates the antioxidant responsive element (ARE) upon exposure to oxidative insults. It has recently been demonstrated that in vitro phosphorylation of Nrf2 on Ser40 by protein kinase C (PKC) facilitates the dissociation of Nrf2 from the Keap1 complex (Huang HC, Nguyen T, and Pickett CB. J Biol Chem 277: 42769-42774, 2002). The present study was designed to examine whether PKC is involved in oxidative stress-mediated nuclear translocation of Nrf2 in vivo and, if so, which PKC isoforms are involved. Induction of HO-1 gene expression by phorone, a glutathione depletor, and 4-hydroxy-2,3-nonenal (4-HNE), an end product of lipid peroxidation, was suppressed by a specific PKC inhibitor, Ro-31-8220, at concentrations that inhibit all isoforms in WI-38 cells. The induction of HO-1 was not affected by prolonged exposure of the cells to 12-O-tetradecanoylphorbol-13 acetate (TPA), suggesting that TPA-insensitive atypical PKC (aPKC) isoforms are involved. An immunocomplex kinase assay revealed that phorone and 4-HNE increased aPKCiota activity. In COS-7 cells, 4-HNE induced nuclear translocation of the Nrf2-green fluorescent protein (GFP) fusion protein, but not the Nrf2(S40A)-GFP mutant. In the absence of oxidative insults, the Nrf2(S40E)-GFP mutant was distributed in the nucleus. The Nrf2-GFP accumulation in the nucleus was induced by coexpression of aPKCiota, but not by a kinase inactive mutant aPKCiota(K274W). The activity of an ARE-driven reporter was increased by coexpression of aPKCiota, and this effect was eliminated by Ro-31-8220 in HepG2 cells. The reporter activity induced by 4-HNE was inhibited by coexpression of aPKCiota(K274W). These results suggest that phosphorylation of Nrf2 Ser40 by aPKC(s) is involved in the nuclear translocation and ARE transactivation of Nrf2 by oxidative stress.

Active Transport, Cell Nucleus↗

PubMed2003

GABAergic modulation of hippocampal glutamatergic neurons: an in vivo microdialysis study.

We have demonstrated the effects of activation of presynaptic gamma-aminobutyric acid (GABA) receptors on glutamate release using in vivo brain microdialysis. A dialysis probe inserted into the hippocampus CA2 area of freely moving rats was perfused with Ringers solution containing 100 mM potassium chloride (KCl) or 0.05 mM veratridine for 20 min. Extracellular concentrations of amino acids were monitored by measuring their levels in dialysates by high performance liquid chromatography (HPLC) fluorometry. Perfusion with depolarizing agents, such as KCl or veratridine, increased extracellular glutamate levels in the hippocampus. Pretreatment with 1 mM GABA, before perfusion with depolarizing agents, significantly suppressed the depolarizing agent-induced increase in glutamate levels. The GABA(B) receptor agonist baclofen (1 mM) also significantly inhibited the depolarizing agent-induced increase in glutamate levels, whereas the GABA(A) receptor agonist, muscimol, had no affect. Similarly, baclofen (0.5 mM) decreased the KCl (13.5 mM)-induced 45Ca(2+) influx into cortical synaptosomes to 57% of the level induced in the absence of baclofen. On the other hands, GABA did not affect the increases in glycine and taurine level by depolarizing agents. These results suggest that GABA modulates depolarization-evoked glutamate release in the hippocampus by inhibiting Ca(2+) entry into neurons, an effect mediated by presynaptic GABA(B) receptors.

Animals↗

PubMed2003

Effect of P-glycoprotein-mediated efflux on cerebrospinal fluid/plasma concentration ratio.

The ratio of drug levels in cerebrospinal fluid (CSF) to plasma (CSF/plasma) at equilibrium has been viewed as in vivo free fraction (fp) in plasma [CSF/plasma = fp], if no active transport is involved in brain penetration. We determined the CSF/plasma level following oral administration in rats and in vitro rat plasma protein binding for 20 compounds that were synthesized in our institute and have similar physicochemical properties. However, results indicated that the CSF/plasma was not only poorly correlated with fp but remarkably lower than fp in most of the compounds tested, suggesting that certain transporters such as P-glycoprotein (P-gp) located in blood-brain barrier (BBB) may decrease the unbound drug concentration in the brain. We evaluated P-gp-mediated transport activity of the 20 compounds with P-gp (mdr1a)-transfected LLC-PK1 cells and calculated P-gp efflux index (PEI), indicating the extent of P-gp-mediated transport. A plot of the CSF/plasma versus fp/PEI showed a strong correlation (r = 0.93), and the absolute values were almost identical [CSF/plasma = fp/PEI]. These results suggest that P-gp quantitatively shifts the equilibrium of unbound drugs across the BBB. Although we cannot rule out the possibility that endogenous transporters other than P-gp on BBB and/or blood-CSF barrier may affect CSF levels of compounds, the present study indicated that fp and PEI measurements may be useful in predicting in vivo CSF/plasma fractions for central nervous system-targeting drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2002

Butorphanol dependence and withdrawal decrease hippocampal kappa 2-opioid receptor binding.

The present study examines the degree and distribution of alterations in the expression of kappa-opioid receptor subtypes using a model of chronic intracerebroventricular (i.c.v.) infusion of butorphanol. Autoradiographic characterization of binding for brain kappa(1) ([3H]CI-977)-, kappa(2) ([3H]bremazocine in the presence of DAMGO, DPDPE, and U-69,593)- and total kappa ([3H]bremazocine in the presence of only DAMGO and DPDPE)-opioid receptors was performed. Dependence was induced by a 72 h i.c.v. infusion with butorphanol (26 nmol/microl per hour) (butorphanol-dependent). Butorphanol withdrawal was produced by terminating the infusion of butorphanol in dependent animals. Responses were studied 7 h following termination (butorphanol-withdrawal). During both dependence and withdrawal phases, the binding signals for both kappa(1)- and kappa(2)-opioid receptors were significantly increased in certain regions, with especially marked increases in the frontal cortex, nucleus accumbens, parietal cortex, dorsomedial hypothalamus, ventral tegmental area and locus coeruleus. In contrast, a highly specific decrease in kappa(2)-, but increase in kappa(1)-, opioid receptor binding was noted in the hippocampus of rats in both butorphanol-dependent and-withdrawal groups. Therefore, alterations in kappa(1)- and kappa(2)-opioid receptors in the hippocampus may be differently involved in both adaptation to and recovery from chronic exposure to a mixed agonist/antagonist opioid analgesic. These results further illustrate the regional distribution of changes in binding characteristics of rat brain kappa(1)- and kappa(2)-opioid receptor subtypes in an established model of butorphanol dependence and withdrawal.

Animals↗

PubMed2002

Induction of multidrug resistance in MOLT-4 cells by anticancer agents is closely related to increased expression of functional P-glycoprotein and MDR1 mRNA.

PURPOSE: The aim of this study was to investigate the multidrug resistance (MDR) pattern, MDR gene and P-glycoprotein (P-gp) expression, and P-gp function in drug-induced human T-lymphoblastoid leukemia MOLT-4 sublines. METHODS: The MDR sublines were developed by exposing the parental MOLT-4 cells to stepwise increasing concentrations of anticancer drugs daunorubicin (DNR), vinblastine (VBL) and doxorubicin (DOX). Degrees of resistance were assessed in terms of IC(50) values in an MTT assay and the P-gp function was evaluated in terms of rhodamine 123 (Rh123) accumulation and efflux. The percentage of cells undergoing apoptosis was determined by flow cytometry after staining with annexin V-FITC and propidium iodide. The levels of P-gp and MDR mRNA expression were estimated using the PE-conjugated anti-P-gp monoclonal antibody 17F9 and quantitative real-time reverse transcription-polymerase chain reaction. RESULTS: Three MOLT-4 sublines were established and revealed a 2- to 115-fold resistance to the anticancer reagents DNR, VBL and DOX as compared to the parental cell line. The highest MDR was expressed in MOLT-4/DNR cells, which was overcome by the P-gp modulator, cyclosporin A (CsA). The resistant sublines showed a decreased accumulation and an increased efflux of Rh123 in proportion to the degree of resistance, and these were completely reversed in the presence of 8 microM CsA. The decreased apoptotic response in these cell lines was clearly associated with the degree of drug resistance. P-gp antigen and MDR1 mRNA were highly expressed in both the MOLT-4/DNR and MOLT-4/DOX sublines. Less-resistant MOLT-4/VBL cells expressed lower levels of MDR1 mRNA and P-gp, even though the cell line was established by exposing the parental MOLT-4 cells to VBL for longer (5 months) than to the other two reagents (3 months). CONCLUSIONS: MOLT-4 cells were able to acquire a high level of drug resistance by culturing the cells in the presence of certain anticancer drugs, and acquisition of the resistance was relatively reagent-specific. The degrees of resistance to the anticancer drugs were well correlated with the expressions of MDR1 mRNA and functional P-gp, and were also associated with a decreased response to apoptosis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2002

Withdrawal from dependence upon butorphanol uniquely increases kappa(1)-opioid receptor binding in the rat brain.

Changes in kappa(1)-opioid receptor binding have been implicated in the development of dependence upon and withdrawal from butorphanol. Autoradiographic characterization of binding for brain kappa(1)-([3H]CI-977), mu-([3H]DAMGO), and delta-([3H]DPDPE) opioid receptors was performed in rats undergoing naloxone-precipitated withdrawal from dependence upon butorphanol or morphine. Dependence was induced by a 72h i.c.v. infusion with either butorphanol or morphine (26nmol/microl/h). Withdrawal was subsequently precipitated by i.c.v. challenge with naloxone (48 nmol/5 microl/rat), administered 2h following cessation of butorphanol or morphine infusion. During withdrawal from butorphanol, but not morphine, kappa(1)-opioid receptor binding was increased significantly in the frontal cortex, posterior basolateral amygdaloid nucleus, dorsomedial hypothalamus, hippocampus, posterior paraventricular thalamic nucleus, ventral tegmental area and locus coeruleus. In contrast, mu-opioid receptor binding decreased in these brain regions in naloxone-precipitated withdrawal from morphine, but not butorphanol, while binding for delta-opioid receptors was altered in both withdrawal groups. The brain kappa(1)-opioid receptor appears to be more directly involved in the development of physical dependence upon, and the expression of withdrawal from, butorphanol, as opposed to the prototypical opioid analgesic, morphine.

Analgesics, Opioid↗

PubMed2002

Invasive ductal adenocarcinoma of the remnant pancreatic body 9 years after resection of an intraductal papillary-mucinous carcinoma of the pancreatic head: a case report and comparison of DNA sequence in K-ras gene mutation.

Recently, there have been a few case reports of invasive ductal adenocarcinoma (IDC) developed in the remnant pancreas after partial pancreatectomy for intraductal papillary-mucinous neoplasm (IPMN). It is necessary to clarify their histogenetic relationships among two sporadic tumors and their surrounding duct epithelium and it would be more reliable if genetic analysis is added to the conventional histology. We report a 76-year-old woman who received pancreaticoduodenectomy for IPMN with a focal in situ carcinoma (IPMC), which was transitional to the surrounding duct epithelium with papillary proliferation and a wide variety of dysplasia. Nine years after the operation, she died of IDC in the remnant pancreatic body and its surrounding duct epithelium consisted of hyperplastic mucous cells with slight-mild dysplasia. Analysis of K-ras mutation at codon 12 (wild-GGT) by direct sequencing after polymerase chain reaction indicated that their transitioning patterns differed from each other: CGT in IPMC; no mutation in the mildly dysplastic duct epithelium around IPMC; GAT in IDC of the remnant pancreas; and AGT in mucous cell hyperplasia with mild dysplasia close to the IDC. This is the first report in which the DNA sequence of K-ras mutation was determined for the two sporadic pancreatic cancers and surrounding duct changes. The following two suggestions are made: (1) the cell-origin might have differed between the two types of cancer (IDC and IPMC); and (2) no precursor lesion toward IDC or IPMC was identified in their surrounding duct epithelium.

Adenocarcinoma, Mucinous↗

PubMed2002

Main pancreatic duct dilatation: a sign of high risk for pancreatic cancer.

BACKGROUND: The prognosis of pancreatic ductal adenocarcinoma remains very poor, but is better in patients with a small tumor without local infiltration. The identification of the sign of high risk for pancreatic cancer will lead to early detection and improvement of the prognosis of this disease. The purpose of this study was to evaluate the main pancreatic duct dilatation as a sign of high risk for pancreatic cancer. METHODS: The diameter of the main pancreatic duct was measured by ultrasonography. The proportion of cases with main pancreatic duct dilatation was retrospectively examined in a pre-cancer group (39 subjects in whom pancreatic cancer developed more than 1 year later and surgically resected) and in a control group (10 244 subjects). Then the proportions in both groups were compared using the odds ratio. RESULTS: The proportion of cases with a slight dilatation (>/=2 mm in diameter) of the main pancreatic duct was 65% in the pre-cancer group, more than 4 years before the resection of the pancreatic cancer. In contrast, it was 5.35% in the age-matched control subjects. The odds ratio of 32.5 (95% confidence interval: 10.9-107.3) shows a significant association between the main pancreatic duct dilatation and the pre-cancer condition. Moreover, the proportion and the mean diameter of the dilated duct in the pre-cancer group increased with time. CONCLUSION: Slight dilatation of the main pancreatic duct appears to be a sign of high risk for pancreatic cancer. The systematic examination of high-risk subjects is recommended for the early detection of pancreatic cancer.

Adolescent↗

PubMed2002

Induction of apoptosis in human lung fibroblasts and peripheral lymphocytes in vitro by Shosaiko-to derived phenolic metabolites.

Shosaiko-to is a Kampo medicine used for the treatment of chronic hepatitis in Japan. Lately, over 200 cases of interstitial pneumonia have been reported resulting from Shosaiko-to therapy, and the number of cases increased when patients were administrated interferon (IFN)-alpha at the same time. However, the mechanisms of this Shosaiko-to implicated interstitial pneumonia are not fully understood. In this study, we examined by flow cytometry analysis the in vitro effects of 7 phenolic compounds (lignans and flavonoids), which were detected from human urine after administration of Shosaiko-to, and IFN-alpha on inducing apoptosis in human lung fibroblasts and peripheral blood mononuclear cells (PBMCs). Among the 7 compounds, baicalein and medicarpin (10 microg/ml) showed significant apoptosis-inducing effects on human PBMCs. In human lung fibroblasts, medicarpin exhibited a significantly higher activity to induce apoptosis compared to the control, and the percentage of cells undergoing apoptosis showed time- and dose-dependent increases. Baicalein (0.1 and 1 microg/ml), liquiritigenin (10 microg/ml) and davidigenin (10 microg/ml) also showed significant effects after 96 h treatment. Whereas, baicalin, oroxylin A and wogonin did not show any effect on inducing apoptosis in PBMCs and fibroblasts. Baicalein and medicarpin significantly inhibited the growth and reduced the viability of lung fibroblasts. IFN-alpha had no apoptosis-inducing effect, and it did not show synergistic interaction with any of the compounds derived from Shosaiko-to on inducing apoptosis in both human lung fibroblasts and PBMCs. These results suggested that phenolic compounds found in human post-administrative urine of Shosaiko-to, especially baicalein and medicarpin, exhibited a direct effect on human lung fibroblasts and immune cells to induce apoptosis.

Antineoplastic Agents↗

PubMed2002

Dynamic sonography of pancreatic tumors: comparison with dynamic CT.

OBJECTIVE: The aim of this study was to examine the usefulness of dynamic sonography in the characterization of pancreatic tumors. MATERIALS AND METHODS: IV contrast-enhanced pancreatic sonography (dynamic sonography) with Levovist was performed in 43 patients with pancreatic mass lesions (32 with pancreatic adenocarcinomas, four with inflammatory pancreatic masses, three with islet cell tumors, two with serous cystadenomas, one with a solid and cystic tumor, and one with metastatic pancreatic cancer). We calculated a contrast index using a time-intensity curve: contrast index equals elevation of intensity in the tumor divided by elevation of intensity in the pancreatic parenchyma. We classified the tumors into three groups according to the contrast index: a slightly enhanced group (contrast index < 0.5), a moderately enhanced group (contrast index = 0.5-1.5), and a well-enhanced group (contrast index > 1.5), and we compared these results with those from dynamic CT. RESULTS: The contrast indexes of 32 adenocarcinomas, four inflammatory pancreatic masses, three islet cell tumors, two serous cystadenomas, one solid and cystic tumor, and one metastatic tumor were, respectively, 0.12 +/- 0.095 (mean +/- SD), 0.54 +/- 0.420, 1.74 +/- 0.555, 1.09 +/- 1.380, 1.67, and 2.07. Thirty-five tumors, including all 32 adenocarcinomas, were classified in the slightly enhanced group, three were classified in the moderately enhanced group, and five were classified in the well-enhanced group. In 93% (40/43) of tumors, the grade of enhancement on dynamic sonography was closely correlated with the grade of enhancement on dynamic CT. CONCLUSION: Dynamic sonography can assist in the characterization of pancreatic tumors.

Adenocarcinoma↗

PubMedDate not supplied

Radical resection for pancreatic cancer.

Ductal adenocarcinoma of the pancreas is still characterized by (1) poor prognosis after surgery and (2) extreme difficulty in early diagnosis, and we need a breakthrough. For the first problem, we have performed a wide range of lymphatic and connective tissue clearance (extended pancreatectomy) which has succeeded in improving the 5-year survival rate from 8% to 24% via decreasing the incidence of locoregional recurrence. When liver perfusion chemotherapy via the hepatic artery and the portal vein was added to the patients who had received extended pancreatectomy, the 5-year survival rate was further elevated to 40% via decreasing the incidence of hepatic metastasis. We conclude that pancreatic cancer should be treated by the better-balanced treatments between locoregional control and prevention of hepatic metastasis. For the second problem, we have more actively collected pancreatic juice to perform cytodiagnosis even though no obvious tumor was delineated by the conventional imaging diagnoses. When cancer cells were detected in the pancreatic juice, our method of intraoperative cytology was very useful in precisely locating the occult lesion indicating an appropriate range of pancreatectomy. The resected pancreas was proven to have included borderline malignancy and in situ or minimally-invasive carcinoma by the postoperative histology, and disease-free 5-year survival rate was 100%. In the future, we need to detect patients with a high risk of pancreatic cancer and develop a less-painful method to collect the pancreatic juice.

Adenocarcinoma↗