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Biomedical subjects

T Yoshikawa

Publications and source records attributed to T Yoshikawa.

At least 271 records · Page 15Linked to original sources
PubMed1999

High incidence of synchronous cancer of the oral cavity and the upper gastrointestinal tract.

A high incidence of synchronous esophageal or gastric carcinoma in preoperative patients with carcinoma of the oral cavity was reported. Esophageal carcinoma was found in seven out of 56 patients (12.5%) and gastric cancer in five patients (8.9%) by videoendoscopy aided with lugol staining in the esophagus and indigocarmine solution in the stomach, although all patients were completely asymptomatic for these lesions. All patients were male, regular drinkers and heavy smokers. The depth of invasion of such tumors was limited to either mucosa or submucosa. Those esophageal and gastric lesions beside the primary oral cancers were positive for p53 protein by immunohistochemistry. Careful preoperative evaluation of not only the esophagus but also the stomach should be a routine procedure in patients with carcinoma of the oral cavity.

Aged↗
PubMed1999

Influence of the non-competitive NMDA receptor antagonist MK-801 on 2-deoxy-D-glucose-induced hyperphagia in rats.

The effects of the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclo-hepten-5, 10-imine (MK-801) on 2-deoxy-D-glucose-induced hyperphagia were investigated in rats. MK-801 significantly increased 2-deoxy-D-glucose-elicited eating. The facilitating effects of MK-801 on 2-deoxy-D-glucose-elicited feeding were not affected by coadministration of a nitric oxide (NO) precursor, L-arginine. Because NO synthase inhibitors inhibit 2-deoxy-D-glucose-induced hyperphagia and activation of the NMDA receptor leads to NO formation, our results suggest that blockade of the NMDA receptor increases 2-deoxy-D-glucose-induced hyperphagia, which is unrelated to inhibition of NO, and that NMDA receptors may play a role in satiety.

Animals↗
PubMed1999

Inhibition of Vpr-induced cell cycle abnormality by quercetin: a novel strategy for searching compounds targeting Vpr.

Vpr, an accessory gene product of HIV-1 which induces cell cycle abnormality leading to the increased HIV replication, is supposed to be a possible target for anti-AIDS drugs. We recently established a cell line (MIT-23) in which Vpr-induced cell cycle perturbation could be manipulated by a tetracycline promoter. Here, we screened anti-Vpr activity in 27 kinds of herb drugs using MIT-23 cells. One of the extracts prepared from Houttuyniae herba showed an inhibitory activity. Quercetin (QCT), a compound of this crude drug, efficiently inhibited Vpr function without affecting its expression. Furthermore, data suggested that Vpr-induced transcription from HIV-LTR was considerably abrogated by QCT. These data indicate that QCT, a flavonoid previously reported to inhibit HIV replication, also targets Vpr, implicating that MIT-23 cell provides a novel strategy for screening compounds possessing anti-Vpr activity which would be in turn utilized for clarifying the mechanism of Vpr function.

Anti-HIV Agents↗
PubMed1999

A neuronal nitric oxide synthase inhibitor 7-nitroindazole reduces the 5-HT1A receptor against 8-OH-DPAT-elicited hyperphagia in rats.

The effects of the neuronal nitric oxide (NO) synthase inhibitor 7-nitroindazole on 8-hydroxy-2-di-n-(propylamino)tetralin (8-OH-DPAT)-induced hyperphagia, which is mediated by the 5-HT1A autoreceptor, were investigated in rats. 7-Nitroindazole suppressed 8-OH-DPAT-elicited increases in food intake. The inhibitory effects of 7-nitroindazole on 8-OH-DPAT-induced feeding were prevented by the NO precursor L-arginine. Although 8-OH-DPAT decreases 5-hydroxytryptamine (5-HT) synthesis, 7-nitroindazole did not reverse the 8-OH-DPAT-elicited decrease in 5-HT synthesis. Therefore, these results indicate that NO formed in the brain is involved in 8-OH-DPAT-induced hyperphagia and that the hypophagic effects of 7-nitroindazole are not dependent on 5-HT synthesis.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1999

Insulin resistance was connected with the alterations of substrate utilization in patients with cancer.

To elucidate the contribution of insulin resistance to substrate utilization, insulin sensitivity and substrate oxidation were examined in 19 cancer patients and five normal controls using the euglycemic hyperinsulinemic glucose clamp technique combined with indirect calorimetry. Glucose uptake and storage were significantly decreased in cancer patients compared with that of controls. In cancer patients, both glucose storage and oxidation were positively correlated with metabolized glucose as measured by the M value in cancer patients. Decrease in glucose uptake was mainly a reflection of decreased glucose storage rather than glucose oxidation. Inversely fat oxidation was negatively correlated with both the M value and glucose oxidation in cancer patients. In cancer patients with insulin resistance, decreased glucose uptake was closely associated with a rapid decrease in glucose storage, an increase in fat oxidation and a mild decrease in glucose oxidation, suggesting that insulin resistance was connected with the alterations of substrate utilization which may induce host depletion.

Adult↗
PubMed1999

Glucose uptake in the human gastric cancer cell line, MKN28, is increased by insulin stimulation.

The expression of the insulin-responsive glucose transporter (GLUT) 4 was studied in three histologically different human gastric cancer cell lines, MKN28, MKN45, and STSA. RT-PCR demonstrated GLUT1 and GLUT4 mRNA in all three cell lines. MKN28 cells expressed GLUT4 protein more than MKN45 and STSA cells by immunohistochemistry. Insulin stimulation of MKN28 cells resulted in a 22% increase in glucose uptake over that found under basal conditions (0.60 +/- 0.05 fmol/cell per min after insulin stimulation versus 0.53 +/- 0.07 fmol/cell per 3 min at basal). No increase in glucose uptake occurred with insulin stimulation in MKN45 or STSA cells. We conclude that the insulin responsive GLUT4 is expressed in MKN28, MKN45, and STKM1 human gastric cancer cell lines, albeit in different amounts. The greater expression of this transporter in MKN28 cells is likely responsible for the cell's ability to increase glucose uptake with insulin stimulation. However, the role played by GLUT4 in regulating the amount of glucose uptake would not be large in those human gastric cancer cell lines.

Biological Transport↗
PubMed1999

Erythrocyte Na+, K+-ATPase activity in patients with congestive heart failure.

In order to determine if the Na+, K+-ATPase activity in erythrocyte membranes is altered in congestive heart failure, and to examine its clinical significance with respect to other clinical variables, erythrocyte Na+, K+-ATPase activity was measured in 51 patients with left ventricular ejection fractions <40% (coronary artery disease, n=26; dilated cardiomyopathy, n=25) and 24 control patients. Na+, K+-ATPase activity was lower in both coronary artery disease and dilated cardiomyopathy groups than control group even in the absence of digitalis use. There was a significant inverse correlation between Na+, K+-ATPase activity and plasma norepinephrine. The presence of non-sustained ventricular tachycardia was associated with a lower Na+, K+-ATPase activity in both groups with congestive heart failure without digitalis use than those without ventricular tachycardia. Plasma norepinephrine was higher in patients with non-sustained ventricular tachycardia than those without in the coronary artery disease group, but not in the dilated cardiomyopathy group. Na+, K+-ATPase activity may be helpful in predicting electrophysiologic instability in patients with heart failure.

Adult↗
PubMed1999

A high-density genome scan detects evidence for a bipolar-disorder susceptibility locus on 13q32 and other potential loci on 1q32 and 18p11.2.

Bipolar disorder is a severe mental illness characterized by mood swings of elation and depression. Family, twin, and adoption studies suggest a complex genetic etiology that may involve multiple susceptibility genes and an environmental component. To identify chromosomal loci contributing to vulnerability, we have conducted a genome-wide scan on approximately 396 individuals from 22 multiplex pedigrees by using 607 microsatellite markers. Multipoint nonparametric analysis detected the strongest evidence for linkage at 13q32 with a maximal logarithm of odds (lod) score of 3.5 (P = 0. 000028) under a phenotype model that included bipolar I, bipolar II with major depression, schizoaffective disorder, and recurrent unipolar disorder. Suggestive linkage was found on 1q31-q32 (lod = 2. 67; P = 0.00022) and 18p11.2 (lod = 2.32; P = 0.00054). Recent reports have linked schizophrenia to 13q32 and 18p11.2. Our genome scan identified other interesting regions, 7q31 (lod = 2.08; P = 0. 00099) and 22q11-q13 (lod = 2.1; P = 0.00094), and also confirmed reported linkages on 4p16, 12q23-q24, and 21q22. By comprehensive screening of the entire genome, we detected unreported loci for bipolar disorder, found support for proposed linkages, and gained evidence for the overlap of susceptibility regions for bipolar disorder and schizophrenia.

Bipolar Disorder↗
PubMed1999

A novel chemical delivery system for brain targeting.

Two different chemical approaches for brain drug delivery and targeting are proposed in the present review. One is a chemical drug delivery using a ring-closure reaction to the hydrophilic quaternary thiazolium compound in the brain. The other is a chemical drug targeting utilizing the nutrient receptor (transporter) system on the blood-brain barrier. The brain delivery system has been optimized and it was demonstrated that the brain delivery of three drugs, a drug for Parkinson's disease, an excitatory amino acid antagonist and a free radical scavenger, were improved by the conjugation with cis-2-formylaminoethenylthio derivatives in vivo. As for the brain targeting system, it was demonstrated that the conjugation with L-Glu improved the drug's brain distribution via the L-Glu excitatory and/or transport receptors in vitro and in vivo. These findings suggest that the concepts of two chemical approaches will contribute to the development of new central nervous system drugs.

Journal Article↗
PubMed1999

Inhibition of IRS-1 phosphorylation and the alterations of GLUT4 in isolated adipocytes from cachectic tumor-bearing rats.

Cellular and molecular mechanisms of insulin resistance in isolated adipocytes from methylcholanthrene-induced sarcoma-bearing rats were investigated by measuring 3-O-[14C]methyl glucose transport activity, glucose transporter-4 (GLUT4) protein in both plasma membrane and low-density microsomes, and insulin-stimulated tyrosine phosphorylation of the insulin receptor (IR) and insulin receptor substrate-1 (IRS-1). Compared to both pair-fed and freely fed controls, tumor-bearing rats (TBR) had a decreased insulin-stimulated glucose transport activity with a lower Vmax and a higher EC50. GLUT4 protein in low-density microsomes from adipocytes maintained at the basal state was less in TBR than in controls. In insulin-stimulated adipocytes, GLUT4 protein in plasma membranes was also less in tumor-bearing rats than in controls. Insulin-induced tyrosine phosphorylation of IRS-1 was less in TBR than controls, but that of the IR was similar among the three groups. These data suggest that the insulin resistance seen in adipose cells of these tumor-bearing rats was caused in part by a decreased amount of GLUT4 protein in both basal and insulin-stimulated states resulting from the selective inhibition of insulin-stimulated phosphorylation of IRS-1.

Adipocytes↗
PubMed1999

Molecular mechanisms of neutrophil-endothelial cell adhesion induced by redox imbalance.

Previous studies have implicated a role for intracellular thiols in the activation of nuclear factor-kappaB and transcriptional regulation of endothelial cell adhesion molecules. This study was designed to determine whether changes in endothelial cell glutathione (GSH) or oxidized glutathione (GSSG) can alter neutrophil adhesivity and to define the molecular mechanism that underlies this GSSG/GSH-induced adhesion response. Treatment of human umbilical vein endothelial cell (HUVEC) monolayers for 6 hours with 0.2 mmol/L diamide and 1 mmol/L buthionine sulfoximine (BSO) decreased GSH levels and increased the ratio of GSSG to GSH without cell toxicity. These redox changes are similar to those observed with anoxia/reoxygenation. Diamide plus BSO-induced thiol/disulfide imbalance was associated with a biphasic increase in neutrophil adhesion to HUVECs with peak responses observed at 15 minutes (phase 1) and 240 minutes (phase 2). N-Acetylcysteine treatment attenuated neutrophil adhesion in both phases, which indicated a role for GSH in the adhesion responses. Interestingly, phase 1 adhesion was inversely correlated with GSH levels but not with the GSSG/GSH ratio, whereas phase 2 neutrophil adhesion was positively correlated with GSSG/GSH ratio but not with GSH levels. Intercellular adhesion molecule-1 and P-selectin-specific monoclonal antibodies attenuated the increased neutrophil adhesion during both phases, whereas an anti-E-selectin monoclonal antibody also attenuated the phase 2 response. Pretreatment with actinomycin D and cycloheximide or with competing ds-oligonucleotides that contained nuclear factor-kappaB or activator protein-1 cognate DNA sequences significantly attenuated the phase 2 response, which implicated a role for de novo protein synthesis. Surface expression of intercellular adhesion molecule-1, P-selectin, and E-selectin on HUVECs correlated with the phase 1 and 2 neutrophil adhesion responses. This study demonstrates that changes in endothelial cell GSSG/GSH cause transcription-independent and transcription-dependent surface expression of different endothelial cell adhesion molecules, which leads to a 2-phase neutrophil-endothelial adhesion response.

Cell Adhesion↗
PubMed1999

Al2O3 doped apatite-wollastonite containing glass ceramic provokes osteogenic differentiation of marrow stromal stem cells.

Fresh marrow cells were obtained from femora of Fischer rats and cultured in a medium containing 15% fetal calf serum (FCS) until confluence. After trypsinization, cells were subcultured at a cell density of 100 x 10(3)/35-mm well in the presence of FCS, beta-glycerophosphate, and ascorbic acid phosphate on four different culture substrata. The period of subculture was 2 weeks; the substrata used were the culture dish, apatite-wollastonite containing glass ceramic (AW), hydroxyapatite coated AW (HA/AW), and Al2O3 doped AW (Al/AW). The HA coating was attained by the incubation of AW in simulated physiological solution. The glass matrix of AW and HA/AW contained MgO, CaO, P2O5, and SiO2; Al/AW contained Al2O3 in addition to these components. The subculture on Al/AW substratum showed many alkaline phosphatase (ALP) positive nodules and the highest ALP activity. On a Northern blot analysis the housekeeping gene of beta-actin mRNA was evenly detected from the cells cultured on all substrata; however, bone-specific osteocalcin mRNA was only detected from the cells on Al/AW. These results indicate that Al/AW provokes the osteoblastic differentiation of marrow stromal stem cells.

Alkaline Phosphatase↗
PubMed1999

Doubling time of serum CA 19-9 in the clinical course of patients with pancreatic cancer and its significant association with prognosis.

BACKGROUND AND OBJECTIVES: Pancreatic cancer is generally a disease with a poor prognosis, and relationship between change of serum CA 19-9 level and progression of this disease was investigated with regard to clinical pace of disease and tumor growth. METHODS: CA 19-9 doubling time was examined in 75 patients with pancreatic cancer, including 41 inoperable cases. Then, its relation with their prognosis and change in tumor was evaluated. RESULTS: The doubling time of CA 19-9 and CEA could be calculated in 90.2% and 58.5% of patients with inoperable pancreatic cancer. CA 19-9 doubling time was clearly associated with survival time in inoperable and palliatively operated cases, but not with sex, age, site of the lesion, or liver metastasis, and was significantly correlated with the tumor volume doubling time. CONCLUSIONS: Examination of CA 19-9 doubling time may be useful in clinical evaluation of the prognosis for patients with pancreatic cancer and could possibly prove valuable in terms of the analysis of the growth process in this disease.

Adult↗
PubMed1999

Epimerization of moxalactam by albumin and simulation of in vivo epimerization by a physiologically based pharmacokinetic model.

We investigated the mechanism of epimerization (R to S or S to R) of moxalactam in serum of rats, dogs, and humans. The epimerization of moxalactam occurred in the serum of these animals, but not in the serum filtrate. The albumin fraction of human serum purified by gel filtration catalysed the epimerization of moxalactam at an identical rate to serum, but other fractions (i.e., lipoproteins and globulins) showed slower epimerization. alpha 1-acid glycoprotein, which was eluted in the same fraction with albumin by G-200 gel filtration, did not epimerize moxalactam. The presence of 2 mM warfarin decreased the binding of R- and S-moxalactam and decreased the epimerization of moxalactam in human serum. These results demonstrate moxalactam was epimerized on the warfarin binding site on albumin in serum. Additionally, a physiologically based pharmacokinetic model shows that the epimerization of moxalactam after administration in dogs is simulated by the epimerization in serum.

Animals↗
PubMed1999

Characteristics of the production of active oxygen species from adherent and non-adherent neutrophils.

Our objective was to evaluate the characteristics of the production of AOS from the neutrophils that had adhered to the endothelial cells, fibronectin or polystyrene, using the method of electron paramagnetic resonance (EPR) spin trapping. Neutrophils and endothelial cells were isolated from human venous blood and umbilical veins, respectively. AOS production from neutrophils was not elicited only by adhesion. The stimulation of adherent neutrophils with phorbol myristate acetate (PMA) induced the production of AOS. The production of AOS from adherent neutrophils to endothelial cells, but not to fibronectin or polystyrene, decreased with the interval time between the adhesion and the stimulation by PMA. The amount of AOS produced by the neutrophils adherent to fibronectin or polystyrene was maintained for one hour after stimulation with PMA, whereas that by suspended neutrophils gradually decreased with the time after stimulation. Results indicate that adherent and non-adherent neutrophils exhibit differing time course of AOS production.

Cell Adhesion↗
PubMed1999

Vitamin E protects against polymorphonuclear leukocyte-dependent adhesion to endothelial cells.

We evaluated the effects of alpha-Toc on surface expression of CD11b/CD18 on polymorphonuclear leukocytes (PMN) stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) and oxidized low-density lipoprotein (oxLDL). Incubation of PMN with fMLP (1 microM) or oxLDL (100 microg/mL) increased CD11b/CD18 expression; pretreatment with alpha-Toc reduced in a dose-dependent manner. PMN obtained from healthy adults ingesting 600 mg alpha-Toc per day for 10 days were similarly incubated with fMLP or oxLDL; the surface level of CD11b/CD18 was inversely correlated with serum alpha-Toc concentrations. Adherence of PMN to human umbilical vein endothelial cells was increased by fMLP or oxLDL stimulation but reduced by alpha-Toc pretreatment or anti-CD18 monoclonal antibodies. cAMP-dependent protein kinase (PKA) and protein kinase C (PKC) activity in PMN was also assayed. A PKC inhibitor, but not a PKA inhibitor, suppressed CD11b/CD18 up-regulation, and alpha-Toc slightly decreased fMLP- and oxLDL-induced activation of PKC. These results suggest that alpha-Toc may prevent inflammation by both reducing CD11b/ CD18 up-regulation and decreasing PMN-dependent adherence to EC.

CD18 Antigens↗
PubMed1999

Involvement of nitric oxide in the 5-HT1A autoreceptor-mediated hyperphagia in rats.

Effects of nitric oxide synthase(NOS) inhibitors on 8-hydroxy-2-di-n-(propylamino)tetralin (8-OH-DPAT)-induced hyperphagia which is mediated by the 5-HT autoreceptor were investigated. The non-selective NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and neuronal NOS (nNOS) inhibitor 7-nitroindazole (7-NI) clearly suppressed increases in food intake by 8-OH-DPAT. Both hypophagic effects of L-NAME and 7-NI were reversed by the nitric oxide precursor, L-arginine. The findings suggest that nitric oxide formed in the brain is involved in 8-OH-DPAT-induced hyperphagia.

8-Hydroxy-2-(di-n-propylamino)tetralin↗