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Biomedical subjects

K Tsuchida

Publications and source records attributed to K Tsuchida.

At least 73 records · Page 4Linked to original sources
PubMed1999

Analysis of affinities of penicillins for a class C beta-lactamase by molecular dynamics simulations.

We present a calculation for the binding free energy difference between two complexes of the class C beta-lactamase from Enterobacter cloacae with foramidocillin (FOPC) and with piperacillin (PIPC). The calculation was carried out by means of the thermodynamic integration (TI) method implemented with molecular dynamics (MD). By use of the available crystal structure of the class C beta-lactamase from E. cloacae, the structures of the beta-lactamase-FOPC (FOPC complex) and beta-lactamase-PIPC (PIPC complex) complexes were built by molecular modeling and equilibrated with MD simulations. FOPC were gradually converted into PIPC in both the solution and the enzyme system by means of MD/TI methods during the MD simulation. The structure of the PIPC complex as derived by the MD/TI simulation was similar to that of the PIPC complex obtained from molecular modeling. The calculated difference in the free energy of binding (deltadeltaGbind) was -2.2 kcal/mol. This compares well with the experimental value of -1.5 kcal/mol. The results indicate that the binding affinity of FOPC is lower than that of PIPC because of the greater difficulty of desolvation for FOPC upon binding to the enzyme. This calculation suggests that the desolvation of the ligand, as well as its interaction with the beta-lactamase, is important in understanding the relative affinity of the ligands with beta-lactamase.

Crystallography↗
PubMed1999

Clinical results of total cystectomy for 92 patients with bladder cancer.

The survival rate of 92 patients with primary bladder cancer who had undergone total cystectomy during a 13-year period from 1984 to 1996 was examined. The mean follow-up period was 1,886 days. The 5-year survival rate was 67.9% and the 10-year survival rate was 55.1%. When survival rates were compared pathohistologically, with 81 patients with transitional cell carcinoma divided into two groups, a high-stage group including T3 and T4 patients and a low-stage group with all other patients, the cancer-specific 5-year survival rate of the low-stage group was 88.9% while that of the high-stage group was 45.4%; this difference was significant (p = 0.0002). There were also significant differences in survival rate between those with and those without regional lymph node metastasis, those with and those without lymphatic infiltration, and those with and those without vascular infiltration. However, there was no significant difference in survival rate for the 34 patients with T3 or T4 disease when those with or without chemotherapy and/or radiation therapy were compared.

Adult↗
PubMed1998

HL-004, the ACAT inhibitor, prevents the progression of atherosclerosis in cholesterol-fed rabbits.

HL-004, N-(2,6-diisopropylphenyl) tetradecylthioacetamide, a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, was evaluated concerning the possible prevention of hyperlipidemia and atherosclerosis in 1% cholesterol-fed rabbits. HL-004 (0.2, 5 and 25 mg/kg) was orally administered once a day for 12 weeks. HL-004 inhibited the rise of total serum cholesterol at a dose of 5 mg/kg and over. In the thoracic aorta, HL-004 at the doses of 5 mg/kg and 25 mg/kg reduced the total cholesterol content by 56.3% and 84.2% compared with control, and decreased ACAT activity, dose-dependently. HL-004 also attenuated the development of aortic lesions. The area of atherosclerotic lesions was reduced by 30.3% with 5 mg/kg of HL-004 and 100% with 25 mg/kg. In this study, we suggest that the main reason for HL-004 preventing the progression of atherosclerosis is its hypocholesterolemic effect due to the inhibition of cholesterol absorption in the intestine.

Acetanilides↗
PubMed1998

The ACAT inhibitor HL-004 inhibits cholesterol absorption and lowers serum cholesterol in rats.

1. HL-004 decreased absorption of cholesteryl ester from the intestine into the lymph in a rat lymph-fistula model. 2. HL-004 reduced serum cholesterol level in acute cholesterol-fed rats. 3. HL-004 simultaneously decreased hepatic cholesteryl ester content and increased free cholesterol in cholesterol-fed rats. 4. These findings suggest that: (1) the hypocholesterolemic effect of HL-004 is principally due to inhibition of cholesterol absorption via inhibition of ACAT in the intestine; and (2) changes in hepatic cholesterol metabolism due to direct inhibition by HL-004 of hepatic ACAT may account in part for reduction of serum cholesterol level by HL-004.

Absorption↗
PubMed1998

Lipid transfer particle catalyzes transfer of carotenoids between lipophorins of Bombyx mori.

The yellow color of Bombyx mori hemolymph is due to the presence of carotenoids, which are primarily associated with lipophorin particles. Carotenoids were extracted from high density lipophorin (HDLp) of B. mori and analyzed by HPLC. HDLp contained 33 micrograms of carotenoids per mg protein. Over 90% of carotenoids were lutein while alpha-carotene and beta-carotene were minor components. When larval hemolymph was subjected to density gradient ultracentrifugation, a second minor yellow band was present, which was identified as B. mori lipid transfer particle (LTP). During other life stages examined however, this second band was not visible. To determine if coloration of LTP may fluctuate during development, we determined its concentration in hemolymph and compared it to that of lipophorin. Both proteins were present during all life stages and their concentrations gradually increased. The ratio of lipophorin: LTP was 10-15:1 during the fourth and fifth instar larval stages, and 20-30:1 during the pupal and adult stages. Thus, there was no correlation between the yellow color attributed to LTP and its hemolymph concentration. It is possible that yellow coloration of the LTP fraction corresponds to developmental stages when the particle is active in carotene transport. To determine if LTP is capable of facilitating carotene transfer, we took advantage of a white hemolymph B. mori strain which, when fed artificial diet containing a low carotene content, gives rise to a lipophorin that is nearly colorless. A spectrophotometric, carotene specific, transfer assay was developed which employed wild type, carotene-rich HDLp as donor particle and colorless low density lipophorin, derived from the white hemolymph strain animals, as acceptor particle. In incubations lacking LTP carotenes remained associated with HDLp while inclusion of LTP induced a redistribution of carotenes between the donor and acceptor in a time and concentration dependent manner. Time course studies suggested the rate of LTP-mediated carotene transfer was relatively slow, requiring up to 4 h to reach equilibrium. By contrast, studies employing 3H-diacylglycerol labeled HDLp as donor particle in lipid transfer assays revealed a rapid equilibration of label between the particles. Thus, it is plausible that the slower rate of LTP-mediated carotene transfer is due to its probable sequestration in the core of HDLp.

Animals↗
PubMed1998

Lixelle adsorbent to remove inflammatory cytokines.

A beta2-microglobulin (beta2M) selective adsorbent (Lixelle) for direct hemoperfusion has been used for the treatment of hemodialysis patients with the long-term complication of dialysis related amyloidosis (DRA), but there is no significant correlation between the serum level of beta2M and the occurrence of DRA. Inflammatory cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor alpha (TNFalpha) are related to the development of DRA. We studied the adsorptive rates of cytokines in vitro using the Lixelle adsorbent. The adsorptive rates were 98.5% for IL-1beta 98.0% for interleukin-1 receptor antagonist (IL-1RA), 82.9% for IL-6, 99.9% for IL-8, 31.2% for TNFalpha, and 46.1% for soluble TNF receptor (sTNFr), respectively. As the molecular weights of cytokines increase, the adsorptive rates decrease. The Lixelle column adsorbed beta2M and various inflammatory cytokines as well. Therefore, the removal of both beta2M and inflammatory cytokines may play an important role in the treatment of DRA.

Adsorption↗
PubMed1998

Solitary rectal ulcer syndrome accompanied by submucosal invasive carcinoma.

We report a case of carcinoma in solitary rectal ulcer syndrome. The diagnosis was made by colonoscopic appearance and biopsy. A tumor measuring 0.9 x 0.6 cm was found in a resected solitary rectal ulcer. The lesion exhibited typical histological features of solitary rectal ulcer syndrome, with a well differentiated adenocarcinoma invading submucosal layers and some dysplastic glands. We believe that the adenocarcinoma represents a malignant transformation from solitary rectal ulcer syndrome, because similar to longstanding chronic idiopathic colitis, colorectal dysplasia and carcinoma may develop.

Adenocarcinoma↗
PubMed1998

Umbilical arterial flow change during hemodialysis.

A pregnant woman was performed hemodialysis 3 times a week from early gestation. At 30 weeks of gestation, fetal growth and amniotic fluid volume were normal. We performed 3-hour hemodialysis 6 times a week. Cesarean section was performed at 38 weeks of gestation, she delivered a healthy neonate weighing 2575 g. During hemodialysis, we performed Doppler flow velocimetry on the umbilical artery. The resistance index revealed a remarkable decrease after 1.5 hour hemodialysis. But it recovered 3 hours of administration as well as after completion of treatment. We speculated this change in the resistance index of the umbilical artery was caused by transient maternal hypovolemia.

Adult↗
PubMed1998

[Relationship between dietary calcium and bone mineral density before menopause].

To study the relationship between dietary calcium intake and bone mineral density (BMD) among young Japanese females, we recruited 1298 females under 40 years living in Yokohama city for BMD measurement by Computed X-ray densitometer (CXD method) and dietary questionnaire. 1. The average of BMD was 2.75 mm/AI and was highest in the 35 to 39 year old group. 2. Calcium intake (Ca) and protein intake (Protein) were highest in 35 to 39 year old group. 3. BMD, Ca, and Protein were significantly higher in those who had regular dietary habits than those with irregular habits. 4. Among those who had lower Ca, (less than 600 mg per day), the amount of small fish consumed whole was negatively correlated with BMD (p = 0.035), and those with higher consumption of small fish than average had significantly (p = 0.018) lower BMD than those with lower small fish consumption adjusting for age and Ca and protein intake. These findings imply a possibility that small fish accompanied by higher salt intake may influence BMD adversely in this population by an interaction with calcium urinary excretion, which has been suggested by experimental and epidemiologic studies. Dietary composition of Ca may be important for prevention of osteoporosis.

Absorptiometry, Photon↗
PubMed1997

Overcoming of multidrug resistance by VA-033, a novel derivative of apovincaminic acid ester.

We have studied the effects of a novel derivative of apovincaminic acid ester, VA-033, on the resistance of tumors to chemotherapeutic agents. VA-033 increased the sensitivity of drug-resistant cell lines (P388/VCR, P388/ADM, AD10, and K562/ADM) to adriamycin or vincristine. The potency of VA-033 was stronger than verapamil. The drug lengthened the survival time of the P388/VCR-implanted mice treated with vincristine. VA-033 increased the intracellular accumulation of vincristine in the tumor cells, and the photolabeling of P-glycoprotein by [3H]azidopine was inhibited by VA-033. VA-033 showed a slight inhibitory effect on the L-type Ca2+ current in the ventricular myocytes, and had less effect on the cardiovascular parameters such as blood pressure, contractile force and atrio-ventricular conduction time than verapamil when administered systemically in the dog. These results suggest that VA-033 may become a beneficial compound as a modifier to the neoplastic cell resistant to multidrugs.

Animals↗
PubMed1997

Phenotypes and invariant alpha beta TCR expression of peripheral V alpha 14+ NK T cells.

A novel subset of peripheral T cells, peripheral NK T cells, is found to be a major population comprising 5% of splenic T and 40% of bone marrow T cells. The majority of peripheral NK T cells are characterized by the expression of an invariant TCR-alpha encoded by V alpha 14/J alpha 281 with a one nucleotide N region. Moreover, a specific reduction of V alpha 14+ NK T cells has been demonstrated to be tightly associated with various autoimmune diseases, indicating their decisive role in autoimmune disease development. In this study, we investigated the phenotypes of peripheral V alpha 14+ NK T cells and their TCR-beta repertoire. Peripheral V alpha 14+ NK T cells, comprise two populations, i.e., small and large sized cells, at an equal frequency, belonged to the CD4- CD8- fraction, and are heat stable antigen(bright), macrophage-1bright, B220bright, CD45RBdim, and Mel-14dim, but CD5-, distinct from thymic NK T cells. TCR-beta analysis clearly showed that peripheral V alpha 14+ NK T cells utilized two to three dominant invariant TCR-beta, such as V beta 8.2 D beta J beta 2.5/V beta 7 D beta J beta 2.1 in the spleen and liver, V beta 8.2 D beta J beta 2.5/V beta 8.3 D beta J beta 2.2/V beta 7 D beta J beta 2.6 in the bone marrow, and V beta 7 D beta J beta 2.1/V beta 3 D beta J beta 1.2 in intestinal intraepithelial lymphocytes. Judging from the unusual surface phenotypes, such as heat stable antigen, macrophage-1, B220, CD45RBdim, and Mel-14dim, which are known to be T cell activation markers, peripheral V alpha 14+ NK T cells may always be activated under physiologic conditions, resulting in the oligoclonal expansion of V alpha 14+ NK T cells with different invariant TCR-beta in different peripheral organs. The unique features of V alpha 14+ NK T cells are discussed.

Amino Acid Sequence↗
PubMed1997

Purification and properties of a lipid transfer particle from Bombyx mori: comparison to the lipid transfer particle from Manduca sexta.

A lipid transfer particle (LTP) was purified from the hemolymph of the silkworm Bombyx mori. Like other insect LTPs, the B. mori LTP is a very high density lipoprotein containing 21% lipid and three apoproteins of mass approximately 350 kDa, approximately 85 kDa, and approximately 60 kDa. B. mori LTP catalyzes the exchange of lipids between different density class lipoproteins found in adult hemolymph and between adult lipoproteins and vitellogenin. However, in no case was net lipid transfer observed. Manduca sexta LTP also catalyzed exchange of lipids, but not net transfer of lipids, between different density class lipoproteins found in adult hemolymph.

Animals↗
PubMed1997

AMPA receptors modulate dopamine release in the striatum, as measured by brain microdialysis.

The effect of 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f) quinoxaline (NBQX), a potent and selective antagonist of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors, on the release of dopamine from the striatum was investigated in freely moving rats using an in vivo microdialysis technique. Perfusion with 1.0 mM AMPA increased the concentration of striatal extracellular dopamine. After systemic administration of NBQX (40 mg/kg, i.p.), dopamine levels in the striatal perfusate decreased. The AMPA-induced increase in dopamine levels was suppressed significantly by the systemic administration of NBQX (40 mg/kg, i.p.). Perfusion with tetrodotoxin (TTX, 5 microM) alone reduced the basal level of dopamine by 80%. Perfusion with 1.0 mM AMPA together with TTX produced a 3.9-fold increase in dopamine efflux from the TTX reduced basal level. However, the maximum dopamine level obtained thereby was close to the basal level of dopamine seen prior to perfusion with TTX. The present results demonstrate that AMPA receptors participate in tonic facilitative modulation of striatal extracellular level of dopamine. In addition, the results support the view that glutamatergic neurons modulate the release of dopamine via subtypes of excitatory amino acid receptors in the central nervous system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Effect of a novel 5-hydroxytryptamine3 (5-HT3) receptor antagonist, GK-128, on 5-HT3 receptors mediating contractions and relaxations in guinea-pig distal colon.

1. We investigated 5-hydroxytryptamine3 (5-HT3) receptor-mediating contractions and relaxations in the guinea-pig isolated distal colon using various 5-HT3 receptor agonists and antagonists, including GK-128 (2-[(2-methylimidazol-1-yl) methyl] benzo[f] thiochromen-1-one monohydrochloride hemihydrate). 2. Selective 5-HT3 receptor agonists, 2-methyl-5-HT and m-chlorophenylbiguanide, produced spantide-insensitive contraction and atropine-insensitive contraction and the relaxation. These agonists showed a small, but significant, difference of potency between contraction and relaxation. 3. GK-128 competitively blocked both 2-methyl-5-HT- and m-chlorophenylbiguanide-induced responses with similar potency. The affinities of GK-128 for spantide-insensitive contraction and atropine-insensitive contraction were ten-fold higher than for relaxation. 4. Other selective 5-HT3 receptor antagonists, azasetron and tropisetron, also exhibited higher affinity in contraction than in relaxation, but the extent of their affinity differences was smaller than that observed in GK-128. In contrast, granisetron, ramosetron and ondansetron exhibited no significant differences in their affinity values among the three responses. 5. These results suggest that the 5-HT3 receptors which mediate contraction and relaxation in the guinea-pig distal colon may not be the same, and that GK-128 is a 5-HT3 receptor antagonist with a stronger potency for contraction.

Animals↗
PubMed1997

Expressions of PDGF receptor alpha, c-Kit and Flk1 genes clustering in mouse chromosome 5 define distinct subsets of nascent mesodermal cells.

In gastrulating embryos, various types of cells are generated before differentiation into specific lineages. The mesoderm of the gastrulating mouse embryo represents a group of such intermediate cells. PDGF receptor alpha (PDGFRalpha), c-Kit and fetal liver kinase 1 (Flk1) are expressed in distinctive mesodermal derivatives of post-gastrulation embryos. Their expressions during gastrulation were examined by whole mount immunostaining with monoclonal antibodies against these three receptors. The antibodies stained different mesodermal subsets in gastrulating embryos. Flow cytometry of head fold stage embryos revealed that Flk1+ mesodermal cells could be further classified by the level of c-Kit expression. To examine the possibility that hematopoietic cell differentiation is initiated from the Flk1+ mesoderm, embryonic stem (ES) cells were cultured on the OP9 or PA6 stromal cell layer; the former but not the latter supported in vitro hematopoiesis from ES cells. Flk1+ cells were detected only on the OP9 cell layer from day 3 of differentiation before the appearance of hematopoietic cells. Thus, Flk1+ cells will be required for in vitro ES cell differentiation into hematopoietic cells. The results suggest that these three receptor tyrosine kinases will be useful for defining and sorting subsets of mesodermal cells from embryos or in vitro cultured ES cells.

Animals↗