Biomedical subjects

T Ishikawa

Publications and source records attributed to T Ishikawa.

At least 307 records · Page 17Linked to original sources

PubMed2000

Effectiveness of the Kampo kami-shoyo-san (TJ-24) for tremor of antipsychotic-induced parkinsonism.

The aim of the present study was to evaluate the effectiveness of the Kampo medication kamishoyo-san against tremor due to antipsychotic-induced parkinsonism. Kami-shoyo-san consists of several medicinal herbs that are known in traditional Chinese medicine to be effective in treating Parkinson's disease and convulsions. We gave kami-shoyo-san to eight patients at Higashiowari National Hospital who were exhibiting tremor, a symptom of antipsychotic-induced parkinsonism. The tremor was evaluated on a five-point scale before and after the administration of kamishoyo-san, and the findings were compared statistically. The results showed a stastistically significant reduction in the tremor after the administration of kami-shoyo-san (P<0.01), with 62.5% of patients showing an improvement of one point or more. The tremor did not worsen in any of the patients, and none complained of side-effects. Thus, kami-shoyo-san appears to be effective against the tremor from parkinsonism. Kami-shoyo-san consists of 10 medicinal herbs, including Radix Bulpleuri, Radix Paeoniae, Radix Angelicae Sinensis, and Radix Glycyrrhizae, which are effective in treating disturbances in muscular movement according to TCM theory. Of the 10 herbs contained in kami-shoyo-san, we believe the abovementioned ones are particularly effective in helping to reduce the tremor associated with parkinsonism.

Acute Disease↗

PubMed2000

Genetic identification of bilateral primary or metastatic nonpapillary renal cell carcinoma.

OBJECTIVE: To clarify the clonality of bilateral tumours by genetic analysis of bilateral renal cell carcinomas (RCCs) using the VHL gene, which is inactivated in approximately 60% of RCCs and which plays a causal role in the development of most cases of nonpapillary RCC. PATIENTS AND METHODS: The study included 20 patients; seven had von Hippel-Lindau disease, three had papillary RCC and 10 had nonpapillary RCC. Paraffin-embedded blocks of tumour tissue were obtained from two of the three patients with papillary RCC and from nine of 10 with nonpapillary disease; all three exons of VHL were examined by direct sequencing. RESULTS: As reported previously, no VHL mutations were found in papillary tumours. However, in five of the nine nonpapillary cases, VHL mutations were identified in tumours on one or both sides. Three of the tumours had the same mutation on both sides, confirming a common origin. In the remaining two patients, the mutation status differed between the sides, confirming a bilateral primary origin. The former cases were characterized by a relatively large tumour on one side and multiple tumours on the other. CONCLUSIONS: In nonpapillary RCC multiplicity may suggest a metastatic origin. Such genetic information will be useful in treating and following patients with bilateral renal tumours.

Aged↗

PubMed2000

Regulation of the epithelial Na+ channel by Nedd4 and ubiquitination.

The epithelial Na+ channel (ENaC) is comprised of three subunits, alpha, beta and gamma, and plays an essential role in Na+ and fluid absorption in the kidney, colon and lung. We had identified proline-rich sequences at the C termini of alpha beta gamma ENaC, which include the sequence PPxY, the PY motif. This sequence in beta or gamma ENaC is deleted or mutated in Liddle's syndrome, a hereditary form of arterial hypertension. Our previous work demonstrated that these PY motifs bind to the WW domains of Nedd4, a ubiquitin protein ligase containing a C2 domain, three or four WW domains and a ubiquitin protein ligase Hect domain. Accordingly, we have recently demonstrated that Nedd4 regulates ENaC function by controlling the number of channels at the cell surface, that this regulation is impaired in ENaC bearing Liddle's syndrome mutations, and that ENaC stability and function are regulated by ubiquitination. The C2 domain is responsible for localizing Nedd4 to the plasma membrane in a Ca(2+)-dependent manner, and in polarized epithelial MDCK cells this localization is primarily apical. In accordance, electrophysiological characterization of ENaC expressed in MDCK cells revealed inhibition of channel activity by elevated intracellular Ca2+ levels. Thus, in response to Ca2+, Nedd4 may be mobilized to the apical membrane via its C2 domain, where it binds ENaC via Nedd4-WW:ENaC-PY motifs' interactions, leading to ubiquitination of the channel by the Nedd4-Hect domain and subsequent channel endocytosis and lysosomal degradation. This process may be at least partially impaired in Liddle's syndrome due to reduced Nedd4 binding, leading to increased retention of ENaC at the cell surface.

Animals↗

PubMed2000

Sinus node recovery time assessment by the overdrive suppression test employing an intravenous injection of disopyramide phosphate.

Although sinus node recovery time (SNRT) assessment by the overdrive suppression test (ODST) is important in detecting sick sinus syndrome (SSS), its sensitivity is still inadequate. We have evaluated the effect of intravenous injection (i.v.) of disopyramide phosphate (DP) in ODST. The subjects were 30 SSS patients (64.9 +/- 10.0 years old). If SNRT was <2,000 ms or the corrected SNRT (CSNRT) was < 1,000 ms, ODST was repeated after DP i.v. (2 mg. kg(-1), < or = 100 mg in total). Eleven normal subjects (59.3 +/- 9.0 years old) were also studied. Although SNRT was <2,000 ms or the CSNRT was < 1,000 ms in 13 of the 30 SSS patients (43%), SNRT was prolonged from 1,510 +/- 300ms to 3,400 +/- 1,160 ms (P<0.01), and CSNRT from 510 +/- 190 to 2,470 +/- 1,470 ms (P<0.01) after DP i.v. in these patients. Thus, SNRT was > or = 2,000 ms and the CSNRT was > or = 1,000 ms in 27 of 30 SSS patients (90%) after DP i.v. Using a combination of overdrive suppression and intravenous injection of disopyramide phosphate, the corrected sinus node recovery time was diagnostic (>525 ms) in 29 of the 30 patients (97%). In contrast, SNRT and CSNRT were shortened in the normal subjects during ODST after DP i.v. (P<0.01). The plasma concentration of DP estimated in nine patients was 4.1 +/- 1.0 microg.ml(-1). No serious side effect occurred. ODST employing DP i.v. is safe and seems to be highly effective in diagnosing SSS.

Aged↗

PubMed2000

Long-term administration of highly purified eicosapentaenoic acid ethyl ester improves the dysfunction of vascular endothelial and smooth muscle cells in male WBN/Kob rats.

We investigated the effect of long-term administration of highly purified eicosapentaenoic acid ethyl ester (EPA-E), an n-3 polyunsaturated fatty acid, on the dysfunction of the endothelium and smooth muscle cells in male WBN/Kob rats, a model of spontaneous diabetes mellitus. After oral 8-month treatment with EPA-E, the agent significantly and dose-dependently increased the migration activity of vascular endothelial cells and also decreased 5-bromodeoxyuridine (BrdU) uptake by vascular smooth muscle cells at a dose of 0.1 g/kg or higher. In addition, there were significant correlations between the endothelial cell migration or smooth muscle cell proliferation and the 4-hour fasting glucose level. These findings suggest that EPA-E has a suppressive effect on thrombosis and atherosclerosis.

Animals↗

PubMed2000

Long-term administration of highly purified eicosapentaenoic acid ethyl ester prevents diabetes and abnormalities of blood coagulation in male WBN/Kob rats.

We investigated the effect of long-term administration of highly purified eicosapentaenoic acid ethyl ester (EPA-E), an n-3 polyunsaturated fatty acid, on the development of diabetes, insulin resistance, and abnormalities of blood coagulation in male WBN/Kob rats, a model of spontaneous diabetes mellitus. After 8-month oral EPA-E treatment, the incidence of diabetes at a dose of 0.1, 0.3, and 1.0 g/kg was 92%, 50%, and 17%, respectively. Its incidence was suppressed significantly and dose-dependently at a dose of 0.3 g/kg or higher compared with the rate (100%) for the vehicle control. Additionally, EPA-E significantly and dose-dependently decreased the elevation of plasma glucose after an oral glucose load and increased the glucose infusion rate (GIR) during the euglycemic insulin-glucose clamp test at a dose of 0.1 g/kg or higher compared with the vehicle control. Furthermore, EPA-E significantly and dose-dependently ameliorated coagulation-related parameters, including the prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen level, and factor II, V, VII, VIII, IX, X, XI, and XII and antithrombin III (AT III) activities, and fibrinolysis-related parameters, including plasminogen, tissue-type plasminogen activator (t-PA), alpha2-plasmin inhibitor (alpha2-PI), and plasminogen activator inhibitor (PAI), and also suppressed ADP- or collagen-induced platelet aggregation and the cholesterol to phospholipid (C/P) molar ratio in platelet membranes at a dose of 0.1 g/kg or higher. These data demonstrate multiple actions of the product in these laboratory animals. These include changes in platelet function, coagulation/fibrinolysis factors, plasma immunoreactive insulin secretion, and plasma glucose/insulin resistance.

Animals↗

PubMed2000

Isoflavonoids from Pueraria mirifica and their estrogenic activity.

Nine isoflavonoids including a new pterocarpene, puemiricarpene, were isolated from the tuberous root of Pueraria mirifica (Leguminosae). The structure of puemiricarpene was determined by spectroscopic means. Estrogenic activity of the isolated isoflavonoids was tested using MCF-7 human breast cancer cells. Moderate activity was observed for kwakhurin, a prenylated isoflavonoid.

Estrogens, Non-Steroidal↗

PubMed2000

Coumarins and antiplatelet constituents from the root bark of Zanthoxylum schinifolium.

Further study on the chloroform-soluble portion of the root bark of Zanthoxylum schinifolium led to the isolation of eight new coumarins: methylschinilenol (1), hydroxyepoxycollinin I (2), 8-methoxyanisocoumarin H (3), hydroxyschininallylol (4), hydroxyepoxycollinin II (5), schinitrienin (6), schininallylone (7), and isoschinilenol (8), along with twenty-six known compounds including fourteen coumarins, and nine alkaloids. The structural elucidation was determined by spectroscopic data. Among the isolates, terpenyl-coumarins and furoquinolines were the active constituents with antiplatelet aggregation in vitro and collinin (10) showed significant anti-HBC DNA replication activity.

Coumarins↗

PubMed2000

A defect in a single allele of the Mlh1 gene causes dissociation of the killing and tumorigenic actions of an alkylating carcinogen in methyltransferase-deficient mice.

Mice with mutations in both alleles of the Mgmt and the Mlh1 gene, the former encoding a DNA repair methyltransferase and the latter a protein functioning at an early step of mismatch repair, are as resistant to the killing action of alkylating agents as are wild-type mice. These mice yielded a large number of tumors when exposed to alkylating carcinogens, but this characteristic was subdued since they also showed a relatively high level of spontaneous tumorigenicity, as a consequence of the defect in mismatch repair. This complexity is now resolved by introducing the Mlh1(+/-) mutation, instead of Mlh1(-/-), in these methyltransferase-deficient mice. Mgmt(-/-) Mlh1(+/-) mice, with about half the amount of MLH1 protein as Mgmt(-/-) Mlh1(+/+) mice, were resistant to the killing action of N-methyl-N-nitrosourea (MNU), up to the level of 30 mg/kg body wt. Eight weeks after exposure to this dose of MNU, 40% of MNU-treated Mgmt(-/-) Mlh1(+/-) mice had thymic lymphomas and there were no tumors in those mice not given the treatment. It seems that the cellular content of MLH1 protein is a critical factor for determining if damaged cells enter into either one of the two pathways leading to mutation induction or to apototic cell death. Loss of Mlh1 expression was frequently observed in tumors of Mgmt(-/-) Mlh1(+/-) mice and this might be related to progression of the tumors.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Analysis of individual specific cytotoxic T lymphocytes for two MAGE-3-derived epitopes presented by HLA-A24.

BACKGROUND: The human MAGE-3 gene encodes tumor-specific antigens that are recognized by cytotoxic T lymphocytes (CTLs) and expressed in a high percentage of various malignant tumors. Of the five MAGE-3-derived CTL epitopes identified to date, two nonapeptides (TFPDLESEF and IMPKAGLLI, designated MAGE-3.A24a and MAGE-3.A24b, respectively) can be expressed on the tumor surface by binding to the HLA-A24 molecule, which is the most frequent HLA class I molecule in Asian populations. To compare the immunogenecities of the two peptides, individual specific CTL lines were generated for each peptide (MAGE-3.A24a and MAGE-3.A24b). METHODS: Peripheral blood mononuclear cells (PBMCs) from four HLA-A24+ healthy donors were stimulated in vitro with autologous dendritic cells pulsed with MAGE-3.A24a, MAGE-3.A24b or both and were subsequently cultivated with a cytokine combination including interleukin-2. RESULTS: We succeeded in generating peptide-specific CTL lines in two of the four donors. The two CTL lines showed similar cytolytic levels against three MAGE-3+/HLA-A24+ cancer cell lines and also target cells pulsed with the corresponding peptide. Cytolytic activities were blocked by either anti-CD8 or anti-HLA-A24 monoclonal antibodies. CONCLUSIONS: The results suggest that MAGE-3.A24a and MAGE-3.A24b peptides have equal potential in inducing MAGE-3-specific and HLA-A24-restricted CTLs.

Antigens, Neoplasm↗

PubMed2000

Association between p53 immunostaining and cigarette smoking in squamous cell carcinoma of the esophagus.

BACKGROUND: It is generally accepted that cigarette smoking is closely associated with esophageal squamous cell carcinoma. This study investigated the molecular targets of cigarette smoke in carcinogenesis of the esophagus. METHODS: Seventy-four patients with esophageal squamous cell carcinoma (SCC) were grouped according to daily cigarette consumption: heavy smoking group (group H) (n = 26), moderate smoking group (group M) (n = 39) and non-smoking group (group N) (n = 9). We compared p53 and retinoblastoma (RB) expression among the three groups by immunohistochemistry. In addition, fresh tumor tissues from 30 smokers with esophageal SCC were tested for p53 mutations in exons 5-8 by direct sequencing. RESULTS: Staining for the p53 product was positive in 65.4% of group H, 38.5% of group M and 44.4% of group N. The frequency of positive staining in the group H was significantly higher than in group M (p = 0.033) and in group M + group N (p = 0.034). The difference with respect to the frequency of overexpression of RB was not significant. The patterns of p53 base-pair mutations in direct sequencing study were of five types, most commonly G:C to T:A transversion (35.3%). CONCLUSIONS: Our study suggests that one of the molecular targets of cigarette smoke is the p53 gene. The pattern of p53 point mutations involved a wide range of base-pair changes.

Aged↗

PubMed2000

Cell surface activities of the human type 2b phosphatidic acid phosphatase.

Several isozymes of mammalian type 2, Mg(2+)-independent phosphatidic acid phosphatase (PAP-2) have recently been cloned, and they are predicted to have their catalytic sites exposed at the cell surface membranes. We investigated the mode of utilization of extracellular lipid substrates by the human PAP-2b expressed in HEK293 cells as a green fluorescent fusion protein. We first confirmed the plasma membrane localization of the expressed PAP-2b. PAP-2b actively hydrolyzed exogenously added lysophosphatidic acid and short-chain phosphatidic acid. In the case of dephosphorylation of lysophosphatidic acid, the reaction products, including inorganic phosphate and monoacylglycerol, were recovered exclusively in the extracellular medium. Interestingly, PAP-2b exhibited negligible activities toward long-chain phosphatidic acid either exogenously when added or generated within the membranes by treating the cells with bacterial phospholipase D. These findings indicate that PAP-2b acts at the outer leaflet of cell surface bilayers and can account for the ecto-PAP activities previously described for various types of cells.

Cell Line↗

PubMed2000

Role of K+ channels in augmented relaxations to sodium nitroprusside induced by mexiletine in rat aortas.

BACKGROUND: A class Ib antiarrhythmic drug, mexiletine, augments relaxations produced by adenosine triphosphate (ATP) sensitive K+ channel openers in isolated rat aortas, suggesting that it produces changes in the vasodilation mediated by ATP-sensitive K+ channels. Nitric oxide can induce its vasodilator effect via K+ channels, including ATP-sensitive K+ channels, in smooth muscle cells. Effects of mexiletine on arterial relaxations to nitric oxide donors, have not been studied. Therefore, the current study in isolated rat aortas was designed to (1) evaluate whether mexiletine augments relaxation in response to nitric oxide donors, including sodium nitroprusside, and (2) determine the role of K+ channels in mediating effects of mexiletine on such nitric oxide-mediated relaxation. METHODS: Rings of rat aortas without endothelia were suspended for isometric force recording. Concentration-response curves of sodium nitroprusside (10(-10) to 10(-5) M) and 1-hydroxy-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (NOC-7; 10(-9) to 10(-5) M) were obtained in the absence and in the presence of mexiletine, in combination with a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo [4,3,-a]quinoxaline-1-one (ODQ), or inhibitors for ATP-sensitive K+ channels (glibenclamide), inward rectifier K+ channels (BaCl2), delayed rectifier K+ channels (4-aminopyridine), large conductance Ca2+-dependent K+ channels (iberiotoxin), or small conductance Ca2+-dependent K+ channels (apamin). RESULTS: Mexiletine (10(-5) or 3 x 10(-5) M) augmented relaxations to sodium nitroprusside and NOC-7. In arteries treated with glibenclamide (10(-5) M), mexiletine (3 x 10(-5) M) did not affect relaxations to nitric oxide donors, whereas mexiletine augmented relaxations to sodium nitroprusside despite the presence of BaCl2 (10(-5) M), 4-aminopyridine (10(-3) M), iberiotoxin (5 x 10(-8) M) and apamin (5 x 10(-8) M). Relaxations to sodium nitroprusside were abolished by ODQ (5 x 10(-6) M), whereas these relaxations were augmented by mexiletine (3 x 10(-5) M) in arteries treated with ODQ (5 x 10(-6) M). CONCLUSIONS: These results suggest that ATP-sensitive K+ channels in vascular smooth muscle, contribute to the augmented vasodilator effect of a nitric oxide donor, sodium nitroprusside induced by mexiletine, and that the vasodilator effect is produced, at least in part, via the guanylate cyclase-independent mechanism.

Animals↗

PubMed2000

Long-term changes in body potassium concentration and dose from 40K for a Japanese adult male group.

Total body potassium has been measured for a Japanese adult male group using two whole-body counters. The total body potassium data were analyzed to present the longitudinal data on body potassium concentration in aging individuals. The data for each individual showed that potassium concentration decreased linearly with age from 30 y to 60 y of age. The average decrease rate was -0.0154 +/- 0.0049 g K kg body wt(-1) y(-1). On the other hand, a subject group for each of the 23 years (1975-1998) of the study was divided into three age groups. The same age groups were followed with the course of time to analyze changes in potassium concentration due to other factors besides age. The follow-up study of the same age groups indicated that the average potassium concentration decreased with the course of the 23-y study and that the decrease was due to other factors besides age. The decrease in the average potassium concentration for study subjects is the major cause of the decrease in the average annual dose from 40K. The average annual dose for subjects aged 30-59 y was 194 muGy in 1975, changing to 166 muGy in 1998. The decrease in the average annual dose was about 14% over the 23-y study period.

Adult↗

PubMed2000

Protein kinase C delta but not PKC epsilon activity is involved in contractile potentiation by endothelin-1 in the porcine coronary artery.

To clarify the mechanism of contractile strengthening by endothelin-1 (ET-1), we measured translocation of protein kinase C (PKC) from the cytosol to the membrane fraction in the porcine coronary artery. ET-1 potentiated the serotonin- (5-hydroxytryptamine, 5-HT) induced contraction without any additional increase in myosin light chain phosphorylation. Four PKC isoforms (alpha, beta1, delta, and zeta) were identified but not PKC epsilon. Only PKC delta was translocated from the cytosolic to the membrane fraction during the contractile potentiation by ET-1. Our results suggest that the activity of PKC delta but not PKC epsilon is involved in the contractile strengthening by ET-1 in the porcine coronary artery.

Animals↗

PubMed2000

Expression of spinach ascorbate peroxidase isoenzymes in response to oxidative stresses.

We studied the response of each ascorbate peroxidase (APX) isoenzyme in spinach leaves under stress conditions imposed by high light intensity, drought, salinity, and applications of methyl viologen and abscisic acid. The steady-state transcript level of cytosolic APX remarkably increased in response to high-light stress and methyl viologen treatment, but not in response to the other stress treatments. The transcript levels of the chloroplastic (stromal and thylakoid-bound) and microbody-bound APX isoenzymes were not changed in response to any of the stress treatments. To explore the responses of the APX isoenzymes to photooxidative stress, the levels of transcript and protein and activities of each isoenzyme were studied during high-light stress and following its recovery. The cytosolic APX activity increased in parallel with transcript abundance during high-light stress, while the protein level was not altered. The other isoenzymes showed no significant changes in transcript and protein levels and activities, except for the gradual decrease in chloroplastic isoenzyme activities.

Ascorbate Peroxidases↗

PubMed2000

Protection against malignant progression of spontaneously developing liver tumors in transgenic mice expressing O(6)-methylguanine-DNA methyltransferase.

To study the effect of O(6)-methylguanine-DNA methyltransferase (MGMT) on carcinogenesis, we have previously generated MGMT transgenic mice overexpressing the bacterial MGMT gene, ada, and demonstrated that high MGMT levels in the liver suppress induction of liver tumors after treatment with an alkylating hepatocarcinogen. To examine the effects of life-long elevation of MGMT activity on mouse spontaneous liver tumor development, ada-transgenic and control non-transgenic mice were compared. We also examined mutations at codon 61 of the H-ras oncogene, reported as a hot spot in mouse liver tumors, using a direct DNA sequencing method. The results revealed no significant difference in tumor incidence or mutation spectrum, but interestingly, ada-transgenic mice were found to have fewer malignant tumors and survived longer, indicating a possible protective role of MGMT against malignant conversion.

Animals↗

PubMed2000

Induction of apoptosis and cell cycle arrest in mouse colon 26 cells by benastatin A.

Benastatin A, isolated from Streptomyces bacteria, is reported to inhibit mammalian glutathione transferases (GSTs). Since GST inhibitors such as ethacrynic acid are suggested to induce apoptosis in some cell lines, the effect of benastatin A on the survival of mouse colon 26 adenocarcinoma cells was compared with that of ethacrynic acid. When cells in stationary phase were treated with benastatin A, viable cells were found to be dose-dependently decreased after 3 days. In the case of ethacrynic acid, this became apparent within 24 h. Electrophoretic analysis revealed DNA fragmentation, indicating that cell loss was due to apoptosis in both cases. The dominant GST in colon 26 cells was identified as the class Pi-form (GST-II), and the activities in crude extracts as well as purified GST-II were almost completely inhibited by 50 microM ethacrynic acid. Immunoblot and northern blot analyses revealed increased GST-II protein and mRNA levels in cells treated with ethacrynic acid. Benastatin A did not significantly affect the activity in the crude extract even at 20 microM, a 10-fold higher concentration than that which almost completely inhibited the activity of purified GST-II. However, GST activity and GST-II protein were decreased in colon 26 cells treated with benastatin A for 5 days, no significant activity being detected in the range of 16 - 20 microM. In addition, beta-actin and bax mRNAs were also decreased in a dose-dependent manner. Furthermore, flow cytometric analysis of colon 26 cells revealed that benastatin A blocked the cell cycle at the G1/G0 phase. Thus, benastatin A also induces apoptosis of colon 26 cells, but this is unlikely to be due to inhibition of GST activity.

Adenocarcinoma↗