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H Ohtani

Publications and source records attributed to H Ohtani.

At least 91 records · Page 5Linked to original sources
PubMed2000

Characteristics of choline transport across the blood-brain barrier in mice: correlation with in vitro data.

PURPOSE: We examined the functional properties of choline transport across the blood-brain barrier (BBB) in mice. We compared the kinetic parameters and transport properties with those found in our in vitro uptake experiments using mouse brain capillary endothelial cells (MBEC4). METHODS: The permeability coefficient-surface area product (PS) values of [3H]choline at the BBB were estimated by means of an in situ brain perfusion technique in mice. RESULTS: [3H]Choline uptake was well described by a two-component model: a saturable component and a nonsaturable linear component. The [3H]choline uptake was independent of pH and Na+, but was significantly decreased by the replacement of Na+ with K+. Various basic drugs, including substrates and inhibitors of the organic cation transporter, significantly inhibited the [3H]choline uptake. These in situ (in vivo) results corresponded well to the in vitro results and suggest that the choline transporter at the BBB is a member of the organic cation transporter (OCT) family. CONCLUSION: The choline transport mechanism at the BBB is retained in MBEC4.

Algorithms↗
PubMed2000

Effect of furanocoumarin derivatives in grapefruit juice on the uptake of vinblastine by Caco-2 cells and on the activity of cytochrome P450 3A4.

1. The presence of inhibitors of drug efflux transporters, such as P-glycoprotein (P-gp), in grapefruit juice (GFJ) was confirmed based on the uptake of [(3)H]-vinblastine (VBL) by Caco-2 cells. 2. The uptake of [(3)H]-VBL by Caco-2 cells was significantly increased by the ethyl acetate extract of GFJ as well as by cyclosporin A. The extract was separated on a Cosmosil column and the eluate with 60% methanol increased [(3)H]-VBL uptake, while the activity to inhibit CYP3A4 was greatest in the 70 and 80% eluates. 3. These results show that the major inhibitor of efflux transport of VBL is different from that of CYP3A4. 4. Further separation of the 60% methanol eluate afforded dihydroxybergamottin (DHBG). Both ethyl acetate extract of GFJ and DHBG increased steady-state [(3)H]-VBL uptake by LLC-GA5-COL300 cells. Besides DHBG, other furanocoumarins contained in GFJ, such as bergamottin, FC726, bergaptol and bergapten, increased the steady-state uptake of [(3)H]-VBL by Caco-2 cells. 5. The order of inhibitory potency of these compounds was FC726>DHBG>bergamottin>bergapten>bergaptol . While, the IC(50) values for inhibition of CYP3A4 were 0.075, 0.45, 1.0, 1.0 and >20 microM, respectively. Bergaptol specifically inhibited VBL efflux. 6. DHBG was thus identified as a candidate for inhibitors of VBL transport, together with other furanocoumarins. Moreover, partly involvement of the P-gp inhibition was suggested. 7. Therefore, the inhibition of efflux transport of drugs as well as of drug metabolism by CYP3A4 could be an important cause of drug-GFJ interaction.

3-O-Methylglucose↗
PubMed2000

Endocapillary proliferative glomerulonephritis in a patient with parvovirus B19 infection.

A 45-year-old woman developed acute nephritic syndrome after erythema infectiosum. Laboratory data on admission showed decreased serum C3, C4, and CH50 levels and the presence of both immunoglobulin (Ig) M and IgG antibodies to human parvovirus B19 (HPV). A renal biopsy showed diffuse endocapillary proliferative glomerulonephritis. Immunofluorescence microscopy indicated 2+ granular staining for IgG, IgM, and C3 over the mesangial area and along glomerular capillary walls. HPV antigen was also detected in glomeruli by immunohistochemistry. Electron microscopy showed electron-dense deposits in the subendothelial space and the paramesangial area. These findings suggest that immune complex-type glomerulonephritis is caused by glomerular deposition of HPV antigen-antibody complexes in some patients with HPV infection.

Antigen-Antibody Complex↗
PubMed2000

Hemoperitoneum due to acute cytomegalovirus infection in a patient receiving peritoneal dialysis.

A 27-year-old man receiving continuous ambulatory peritoneal dialysis (CAPD) developed high-grade fever, dyspnea, and hemoperitoneum 32 months after the start of CAPD. A chest computed tomograph showed fine reticular shadows in the bilateral lower lung fields. Cytomegalovirus (CMV) antigenemia were detected, and immunoglobulin (Ig) M and IgG antibodies for CMV were also positive. The absolute counts of helper T cells (478/microL) and the ratio of helper T cells/suppressor T cells (0.25) decreased, despite no evidence of hematologic or immunologic diseases, including human immunodeficiency virus (HIV) or human T cell lymphoma virus-1 (HTLV-1) infection, or the use of immunosuppressive drugs. All symptoms, including hemoperitoneum and the ratio of helper T cells/suppressor T cells, improved gradually and spontaneously. Acute and primary cytomegalovirus (CMV) infection induced hemoperitoneum in a patient who was receiving CAPD.

Acute Disease↗
PubMed2000

Intrahepatic mast cell population correlates with clinical outcome in biliary atresia.

PURPOSE: To determine if mast cells influence the clinical outcome in biliary atresia (BA), the authors examined the intrahepatic mast cell population in BA. METHODS: Mast cells were identified histochemically using Toludin Blue and immunohistochemically using antimast cell tryptase antibody in formalin-fixed paraffin-embedded sections from 21 cases of BA. Patients were divided into 3 groups; group I (n = 8) with good liver function, group II (n = 8) with moderate liver dysfunction, and group III (n = 5) with severe liver dysfunction. Liver biopsies from patients with choledochal cysts (CDC, n = 5), and normal liver (NL, n = 4) served as controls. The results were compared among the groups. RESULTS: Both histochemical and immunohistochemical methods showed similar data. Mast cells were seen mostly in the portal tracts. Mast cell numbers per medium power field (20 x magnification) were higher in BA than in the controls (15. 03 +/- 2.25 v 3.85 +/-.65, [mean +/- SEM], P <.05, BA v CDC; 15.03 +/- 2.25 v 1.73 +/-.06, [mean +/- SEM], P <.05, BA v NL, immunohistochemical data). Clinical correlation showed an association between higher mast cell number and liver dysfunction (32.62 +/-.80 v 8.52 +/-.87 [mean +/- SEM], group III v group I; P <. 05, immunohistochemical data). CONCLUSION: Increased mast cell population in BA adversely affects liver function and raises the possibility that type I allergic reaction may play role in the pathology of BA.

Biliary Atresia↗
PubMed2000

Dynamics of the fluorescence properties of pyrene residues appended to oligonucleotide hybridization probes.

The dynamic and static properties of the fluorescence of a pyrene-introduced oligonucleotide 16 mer and its hybrid with a target 32 mer. Their fluorescence quantum yields (< 1%) were much weaker than that of unsubstituted pyrene and their fluorescence lifetime of the major decay components were less than 1 ns. The rapid fluorescence quenching was due to the interaction between the fluorophore and bases in the oligonucleotides. The fluorescence of pyrene was quenched efficiently by TMP and slightly by AMP. The quenching by CMP and GMP were the intermediate case.

Adenosine Monophosphate↗
PubMed2000

Comparative pharmacodynamic analysis of Q-T interval prolongation induced by the macrolides clarithromycin, roxithromycin, and azithromycin in rats.

In order to evaluate the arrhythmogenic potency of macrolide antibiotics in a quantitative manner, we analyzed the influence of clarithromycin (CAM), roxithromycin (RXM), and azithromycin (AZM) on Q-T intervals from pharmacokinetic and pharmacodynamic points of view and in comparison with the potency of erythromycin (EM) previously reported by us for rats. Male Sprague-Dawley rats were anesthetized, and CAM (6.6, 21.6, and 43.2 mg/kg of body weight/h), RXM (20 and 40 mg/kg/h), and AZM (40 and 100 mg/kg/h) were intravenously injected for 90 min to obtain the time courses of drug concentrations in plasma and the changes in the Q-T intervals during and after the drug injections. Distinct Q-T interval prolongation of up to 10 ms was observed with CAM at its clinical concentrations. RXM and AZM evoked Q-T interval prolongation at concentrations higher than their clinical ranges. The potencies for Q-T interval prolongation, assessed as the slope of the concentration-response relationship, were 6.09, 0.536, and 0.989 ms. ml/microg for CAM, RXM, and AZM, respectively. There was hysteresis between the change in the Q-T intervals and the time course of the plasma concentration of each drug. The rank order of clinical arrhythmogenicity was estimated to be EM > CAM > RXM > AZM, as assessed from the present results and our previous report for EM. In conclusion, RXM and AZM were estimated to be less potent at provoking arrhythmia than EM and CAM. These results should be useful for making a safer choice of an appropriate agent for patients with electrocardiographic risk factors.

Algorithms↗
PubMed2000

Comparison of blood-brain barrier permeability in mice and rats using in situ brain perfusion technique.

Here we present a method for measuring the permeability coefficient-surface area product (PS) values at the blood-brain barrier in mice, using the in situ brain perfusion technique originally developed for rats by Takasato et al. (Am J Physiol Heart Circ Physiol 247: H484-H493, 1984). Retrograde infusion into the right external carotid artery increased the carotid perfusion pressure in proportion to the perfusion rate. Intravascular volume and cerebral perfusion fluid flow at a perfusion rate of 1.0 ml/min in mice were similar to those in rats. In addition, the contribution of systemic blood to total flow in the hemisphere was small (only 3. 2%). These findings indicated that this perfusion rate is suitable for mice. The PS values of more than 20 different compounds were determined in mice by using the in situ brain perfusion technique, and comparisons were made with data from rats. There was a close relationship (1:1) between the PS values in mice and rats, indicating that brain capillary permeabilities are similar in mice and rats.

Animals↗
PubMed2000

Influence of extracellular K+ concentrations on quinidine-induced K+ current inhibition in rat ventricular myocytes.

Hypokalaemia is one of the important risk factors for development of torsades de pointes. We recently reported that hypokalaemia increased the electrocardiographic QT interval in rats treated with quinidine, but did not alter the arrhythmogenic potency of quinidine. In this study, we have investigated the influence of extracellular potassium concentration ([K+]o) on the inhibition of several types of cardiac potassium currents by quinidine. Such types of currents include the delayed rectifier potassium current (I(K)), the transient outward current (Ito), and the inward rectifier potassium current (I(K1)), as measured in isolated rat ventricular cells using patch-clamp techniques. Concentration-dependent effects of quinidine on I(K), Ito, and I(K1) were evaluated under both normal ([K+]o = 5.4 mM) and hypokalaemic ([K+]o = 3.5 mM) conditions. In contrast to both I(K) and Ito, which were barely influenced by changes in [K+]o, I(K1) was significantly inhibited by hypokalaemia. Furthermore, while quinidine suppressed both I(K) and Ito in a concentration-dependent manner, the inhibitory potency of quinidine on these currents was not influenced by changes in [K+]o. The respective normal and hypokalaemic IC50 values for quinidine were 11.4 and 10.0 microM (I(K)), and 17.6 and 17.3 microM (Ito). Although higher concentrations of quinidine were required to inhibit I(K1), the inhibitory potency of quinidine was also found to be insensitive to changes in [K+]o. Thus, in rats, the inhibitory potency of quinidine for the K+ current-types I(K), Ito and I(K1) is barely influenced by changes in [K+]o. These findings are consistent with our previous report showing that the QT-prolonging potency of quinidine was not altered under hypokalaemic conditions. However, whilst hypokalaemia does not affect I(K) or Ito, it can inhibit I(K1) and can result in QT prolongation in-vivo.

Adrenergic alpha-Antagonists↗
PubMed2000

A case of extramedullary plasmacytoma arising from the nasal septum.

A rare case of extramedullary plasmacytoma arising from the nasal septum with localized amyloid deposition is reported. A 75-year-old woman presented with a history of post-nasal discharge and nasal obstruction for several months. Endonasal endoscopic observation revealed the presence of a mass arising from her nasal septum with an extension to the nasopharynx. No cervical lymph nodes were palpable. The biopsy specimen was diagnosed as a plasmacytoma (IgG, lambda-light chain type). Both serum myeloma-protein and urine Bence-Jones protein were negative. Bone marrow biopsy, a chest radiograph, total body skeletal survey and 67Ga- and 99mTc-scintigrams showed no other systemic lesions. These findings confirmed the diagnosis of extramedullary plasmacytoma in the nasal septum. The patient received irradiation of 40 Gy without clinically detectable reduction of tumour size. The patient eventually underwent complete resection of the tumour by KTP/532 laser under endonasal endoscopic control. Pathologically, the tumour mass was composed mainly of amyloid deposition with a marked reduction of tumour cells. This indicated the radiosensitiveness of tumour cells, which was clinically masked by the increased amyloid deposition. The clinical presentation, pathological features and surgical procedures are described with a review of the literature.

Aged↗
PubMed2000

Effects of dibutyl phthalate as an environmental endocrine disruptor on gonadal sex differentiation of genetic males of the frog Rana rugosa.

To examine the effects of dibutyl phthalate (DBP) on gonadal sex differentiation, genetically male tadpoles of Rana rugosa were exposed to dilute solutions of DBP at concentrations of 0.1, 1, or 10 microM during days 19-23 after fertilization, which is the critical period of gonadal sex differentiation in R. rugosa. Tadpoles were necropsied on day 40. The genetically male tadpoles were produced from crossings between males (ZZ) of one local population, in which females are the heterogametic sex, and females (XX) of another local population, in which males are the heterogametic sex. As positive control groups, tadpoles were exposed to dilute solutions of 17beta-estradiol (E(2)) at concentrations of 0. 01, 0.1, or 1 microM during the same period. The internal structure of the gonads was histologically examined in a total of 30 control tadpoles, 86 E(2)-treated tadpoles, and 90 DBP-treated tadpoles. The gonads of the control tadpoles all showed the typical structure of testes. In contrast, 0.01, 0.1, and 1 microM E(2) treatments caused the undifferentiated gonads of 18, 63, and 100% of the tadpoles, respectively, to develop into gonads of complete or partial ovarian structure. After 0.1, 1, and 10 microM DBP treatment, 0, 7, and 17% of tadpoles, respectively, were similarly affected. These findings suggest that DBP was about 1,000-fold less potent than E(2). Nevertheless, DBP is an environmentally dangerous hormone that disrupts the pathways of testicular differentiation in genetically male animals.

Animals↗
PubMed2000

Infiltration of CD8+ T cells in non-small cell lung cancer is associated with dedifferentiation of cancer cells, but not with prognosis.

CD8+ T cells infiltrating within cancer cell nests in human colorectal cancer were associated with a favorable patients' survival, suggesting the presence of anti-tumor immunity. The present study was designed to examine this concept in non-small cell lung cancer (NSCLC) by a retrospective analysis of 128 surgically resected cases. Immunohistochemical analysis showed that the number of CD8+ T cells within cancer cell nests in NSCLC was related to the histological subtype (large cell carcinoma or squamous cell carcinoma > adenocarcinoma) and the degree of dedifferentiation (undifferentiated type > differentiated type). In contrast to colorectal cancer, the number of CD8+ T cells in NSCLC had no statistically significant impact on the patients' survival. The present study demonstrated that the degree of infiltration of CD8+ T cells within cancer cell nests is dependent on the dedifferentiation of cancer cells in NSCLC, which could be one of the important aspects for the study of tumor immunity.

Adenocarcinoma↗
PubMed2000

Efficient introduction of macromolecules and oligonucleotides into brain capillary endothelial cells using HVJ-liposomes.

In this study, we examined the feasibility of introducing macromolecules into cultured mouse brain capillary endothelial cells (MBEC4 cells) by utilizing the hemagglutating virus of Japan (HVJ)-liposomes with fusogenic activity. We used fluorescein isothiocyanate dextran (FITC-Dextran) and FITC-labeled oligodeoxynucleotide (FITC-ODN) as models of a macromolecule and an ODN, respectively. Intracellular fluorescence appeared rapidly after the exposure of MBEC4 cells to FITC-Dextran-containing HVJ-liposomes, and remained detectable for at least 3 days. Only a control level of intracellular fluorescence was seen after treatment with FITC-Dextran alone, FITC-Dextran with empty HVJ-liposomes or FITC-Dextran-containing liposomes without fusogenic activity. In the early phase after administration (0-30 min), the introduction of FITC-Dextran into MBEC4 cells by the HVJ-liposome method resulted in a rapid and time-dependent increase of intracellular fluorescence intensity. Moreover, FITC-ODN was also introduced into MBEC4 cells by the HVJ-liposome method, although FITC-ODN alone was not introduced. These results indicate that the HVJ-liposome method is useful for the efficient introduction of macromolecules, including ODN, into brain capillary endothelial cells.

Animals↗
PubMed2000

Association of renal cell carcinoma antigen, disialylgalactosylgloboside, with c-Src and Rho A in clustered domains at the surface membrane.

Disialylgalactosylgloboside (DSGG), defined by monoclonal antibody RM2, is a renal cell carcinoma (RCC)-associated antigen which mediates adhesion of RCC TOS-1 cells to certain lung tissue target cells. This adhesion process may initiate preferential lung metastasis of RCC. Ganglioside GM3 is a B16 melanoma-associated antigen which similarly adheres to target cells and promotes consequent metastasis. In view of the close association of GM3-enriched microdomain with transducer molecules c-Src, Rho A, and FAK in B16 cells, we investigated the organizational status of DSGG in RCC cell line TOS-1, with the following results: i) DSGG, but not monosialylgalactosylgloboside, showed extensive clustering at the TOS-1 cell surface; ii) a low-density membrane fraction isolated from TOS-1 cells contained >95% of cellular DSGG, although protein content in this fraction was <1% of total cellular protein; iii) this fraction contained c-Src, Rho A, and FAK, but not H-Ras; iv) c-Src and Rho A were co-immunoprecipitated with DSGG through anti-DSGG mAb RM2 (IgM) affixed to a column. These observations indicate that DSGG is clustered in RCC, as typified by TOS-1 cells, to form a microdomain in which it is closely associated with c-Src, Rho A, and FAK, and may constitute a functional unit as has been observed for GM3 with transducer molecules in B16 cells. The functional organization of such units may be essential in determining malignant properties of RCC cells.

Carcinoma, Renal Cell↗
PubMed2000

Polymethoxylated flavones in orange juice are inhibitors of P-glycoprotein but not cytochrome P450 3A4.

The presence in orange juice of compounds that specifically inhibit the P-glycoprotein (P-gp) drug efflux transporter, but not the cytochrome P450 (CYP) isozyme CYP3A4, was investigated. The uptake of [(3)H]vinblastine, a substrate of P-gp, by Caco-2 cells was measured. An ethyl acetate extract of orange juice did not affect the initial uptake rate of [(3)H]vinblastine but significantly increased the steady-state uptake, as did cyclosporin A (20 microM), an inhibitor of P-gp. No significant effect on the uptake of 3-O-[(3)H]methylglucose or [(14)C]phenylalanine by Caco-2 cells was found, compared with the control. When the extract was separated on a Cosmosil column, the eluate with 70% methanol showed the most potent ability to increase [(3)H]vinblastine uptake. Additional separation of the 70% methanol eluate on a silica gel column with hexane-acetone (3:1) gave 3,3',4',5,6,7,8-heptamethoxyflavone (HMF) and 4',5,6,7,8-pentamethoxyflavone (tangeretin). HMF, tangeretin, and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin), another methoxyflavone contained in orange juice, all increased the steady-state uptake of [(3)H]vinblastine by Caco-2 cells in a concentration-dependent manner. The order of potency of these compounds at the concentration of 50 microM was tangeretin > HMF > nobiletin. None of these methoxyflavones inhibited 6beta-hydroxylation of testosterone catalyzed by CYP3A4. The ethyl acetate extract of orange juice and these methoxyflavones also increased steady-state [(3)H]vinblastine uptake by LLC-GA5-COL300 cells (a cell line transfected with human MDR1 cDNA). We conclude that these methoxyflavones enhanced vinblastine uptake by specifically inhibiting drug efflux via P-gp. They may have potential as agents for reversing multidrug resistance or for recovering the bioavailability of certain drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

[Development of gamma-heavy chain disease during the course of diabetic nephropathy].

We reported a rare case of gamma-heavy chain disease. A 63-year-old man had been given a diagnosis of diabetes mellitus at the age of 30 and had received hemodialysis since the age of 55. The patient presented with swollen lymph nodes in the neck. Lymph node biopsy findings suggested immunoblastic lymphadenopathy. The patient was admitted to Kitasato University hospital. Serum protein electrophoresis showed an increase of beta-fraction peak, and immunoelectrophoresis revealed an increase of gamma-heavy chain protein. Further studies of the gamma-heavy chain protein showed that it contained three different components and that the molecular weight of the main component was 34,000 Da. The patient died on the 11th day of hospitalization. The diagnosis at autopsy was unclassified malignant lymphoma.

Diabetic Nephropathies↗