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Biomedical subjects

Y Tsuda

Publications and source records attributed to Y Tsuda.

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

DNA profiling of Acorus calamus chemotypes differing in essential oil composition.

The phylogenetic relationship of Acorus gramineus and three types of Acorus calamus was analyzed by comparing the 700 bp sequence of a 5S-rRNA gene spacer region. Although there was no intra-specific variation in the essential oil profile of A. gramineus which contained a phenylpropanoid (Z-asarone) as a predominant constituent, A. calamus was classified into two chemotypes: chemotype A in which Z-asarone is a major essential oil constituent and chemotype B which contained sesquiterpenoids predominantly. An intermediate type (M) of these two chemotypes in various ratios was also observable. The NJ tree constructed based on the sequences revealed that A. gramineus was clearly distinguished from any of the chemotypes of A. calamus and that the phylogenetic relationship predicted by the spacer region data correlated well with the essential oil chemotype pattern of A. calamus.

Base Sequence↗
PubMed1999

Detection of anaphylactic reaction in the percutaneously sensitized mouse using the AW method.

Anaphylactic reactions of mice sensitized percutaneously with 2,4-dinitrofluorobenzene (DNFB) were investigated by the AW method assay, which is a mouse anaphylactic model using the abdominal wall as the site for induction with either 2,4-dinitrophenyl (DNP)-human serum albumin or anti-mouse IgE antibody and then estimation of the response. DNP-specific and IgE-dependent anaphylactic reaction after contact sensitization with DNFB could be induced and detected by the abdominal wall (AW) method assay in both groups with and without previous ear challenge with DNFB. Thus, the anaphylactic reaction in the group of twice-contact with 0.5% DNFB was observed on the 9th day from the sensitization (5th day from the ear challenge), and the reaction in the group of a single contact with 0.5% DNFB was observed 10 d after sensitization. The DNP-specific anaphylactic reaction was observed earlier than the 10th day with higher doses of DNFB. As for the mice of the former twice-contact group, the first and second characteristic ear swelling responses appeared within 1-6 h and 2 d of the ear challenge, respectively, and small swelling was observed 7 d after the challenge. It is suggested that Th1 and Th2 cells are activated at the almost same time, in other words, the preparation for both cell-mediated and humoral immunity could be accomplished to function, in vivo by a single percutaneous sensitization with DNFB.

Abdominal Muscles↗
PubMed1999

Amino acids and peptides. LIV. Application of 2-adamantyl derivatives as protecting groups to the synthesis of peptide fragments related to Sulfolobus solifataricus ribonuclease. I.

The 2-adamantyloxycarbonyl group was employed for the protection of the epsilon-amino group of Lys and the hydroxyl group of Tyr, and the 2-adamantyl ester was employed for the protection of the beta-carboxyl group of Asp in order to construct eight peptide segments as building blocks for the preparation of peptide fragments related to the sequence of Sulfolobus solifataricus Ribonuclease. The usefulness of the above protecting groups developed in our laboratory was confirmed.

Adamantane↗
PubMed1999

Amino acids and peptides. LV. Application of 2-adamantyl derivatives as protecting groups to the synthesis of peptide fragments related to Sulfolobus solifataricus ribonuclease. II.

Segment condensations were performed to construct peptide fragments related to Sulfolobus solifataricus Ribonuclease. At each condensation step, the new protecting groups were stable. The protected peptide fragments were treated with a low-high HF procedure to give the desired peptide fragments. These peptide fragments were also prepared by the solid-phase method, and the obtained peptides were compared with those obtained by the solution method. The peptide fragments obtained by the solution method were identical with those obtained by the solid-phase method on analytical HPLC, indicating that the new protecting groups could be easily removed by HF, and no racemization occurred during the synthesis of the protected peptides.

Adamantane↗
PubMed1999

Amino acids and peptides. LIII. Synthesis and biological activities of some pseudo-peptide analogs of PKSI-527, a plasma kallikrein selective inhibitor: the importance of the peptide backbone.

Pseudo-peptide analogs of trans-4-aminomethylcyclohexanecarbonyl-L-phenylalanyl-4-aminopheny l acetic acid (PKSI-527, plasma kallikrein selective inhibitor), in which an amide bond (peptide bond) has been replaced by a CH2-NH bond, i.e., trans-4-aminomethylcyclohexanecarbonyl-L-phenylalanyl-psi (CH2-NH)-4-aminophenyl acetic acid (I), trans-4-aminomethylcyclohexanecarbonyl-psi (CH2-NH)-L-phenylalanyl-4-aminophenyl acetic acid (II) and trans-4-aminomethylcyclohexanecarbonyl-D-phenylalanyl-psi (CH2-NH)-4-aminophenyl acetic acid (III) were synthesized. These pseudo-peptide analogs did not exhibit any detectable inhibitory activity against plasma kallikrein (PK), plasmin (PL), urokinase (UK), thrombine (TH) or trypsin (TRY). These results indicate that both carbonyl groups in the PKSI-527 are important for the manifestation of potent inhibitory activity against plasma kallikrein.

Animals↗
PubMed1999

Synthesis of pyrazinone ring-containing opioid mimetics and examination of their opioid receptor-binding activity.

Cyclization of dipeptidyl chloromethyl ketones gave 6-(4-aminobutyl)-3-carboxyethyl-5-methyl-2(1H)-pyrazinone, 3-(4-aminobutyl)-6-carboxyethyl-5-methyl-2(1H)-pyrazinone, and 3,6-bis(4-aminobutyl)-5-methyl-2(1H)-pyrazinone, which were inserted into the enkephalin sequence to give opioid mimetics. Thus, it was confirmed that a pyrazinone ring can be easily inserted into a peptide sequence in order to evaluate structural components required for biologically active peptides.

Chromatography, High Pressure Liquid↗
PubMed1999

Concentration of serum lipids and aortic lesion size in female and male apo E-deficient mice fed docosahexaenoic acid.

Apolipoprotein (apo) E-deficient mice were fed an atherogenic diet with either 1% ethyl ester docosahexaenoic acid (DHA) or safflower oil (SO) as a source of linoleic acid for 8 week. Both genders fed DHA had higher proportions of eicosapentaenoic acid and DHA, and lower proportions of linoleic and arachidonic acids in the liver and serum phospholipids than those fed SO. Males fed DHA had greater liver weight and tended to have higher concentrations of serum lipids and liver cholesterol than those fed SO, and there were opposite trends in females. Dietary fats and gender led to no significant effect on lesion sizes in aortic arch and thoracic plus abdominal aorta. These results indicate that the interactive action of sex-related factor(s) with dietary polyunsaturated fatty acids is involved in metabolic changes of serum lipids in apoE-deficient mice, and addition of DHA, compared with addition of SO, is not effective to abolish the atherosclerosis in this animal model.

Animals↗
PubMed1999

Possible evidence for transmembrane K(+)-H+ exchange system in guinea pig myocardium.

The aim of this study was to obtain evidence for a transmembrane K(+)-H+ exchange system in Langendorff-perfused whole hearts and isolated ventricular myocytes of guinea pig. Effluent relation between K+ and pH in the whole hearts perfused with HEPES-buffered Tyrode's solution indicated a significant (p < 0.05) functional coupling of K+ uptake and H+ extrusion that was energy-dependent and omeprazole (OPZ)-sensitive. Administration of OPZ (0.3 mM) or dimethylamiloride (0.1 mM), an inhibitor of Na(+)-H+ antiport, to whole hearts subjected to the repetitive NH4Cl applications implied that both Na(+)-H+ and putative K(+)-H+ countertransports contribute to the regulation of intracellular pH. In isolated myocytes, voltage-dependent L-type Ca current (ICa) was inhibited by OPZ (0.3 mM) under K(-)- and Na(+)-free condition by 11 to 14%, and was inhibited to a greater extent (i.e., by 36 to 40%) by this agent in the presence of K+. OPZ-induced inhibition of the putative K(+)-H+ exchanger likely resulted in subsarcolemmal acidification which was responsible for the rate-independent suppression of ICa. In conclusion, these data provide functional evidence for a myocardial transmembrane K(+)-H+ exchanger.

Animals↗
PubMed1999

Mechanism of intestinal absorption of an orally active beta-lactam prodrug: uptake and transport of carindacillin in Caco-2 cells.

Absorption characteristics of carindacillin (CIPC) were investigated using Caco-2 cells, and the results were compared with those of its parent drug, carbenicillin (CBPC). Uptake of CBPC was not affected by the metabolic inhibitor or the change in extracellular pH. CBPC appeared to be taken up into Caco-2 cells by passive diffusion. In contrast, the uptake of CIPC was greater at lower extracellular pH and was inhibited in the presence of carbonyl cyanide p-(trifluoromethoxy)phenyl hydrazone, a protonophore. Also, transport of CIPC through Caco-2 cell monolayer was energy and temperature dependent. Moreover, the uptake and transport of CIPC were significantly inhibited in the presence of various monocarboxylic acids, which are the substrates of the monocarboxylic acid transport system(s), whereas the substrates of the oligopeptide transporter had no effect on the uptake or transport of CIPC. These results suggested that the absorption of CIPC may be mediated by the monocarboxylic acid transport system(s), not by the oligopeptide transporter. Furthermore, the uptake and transport of CIPC were approximately 40-fold greater than those of CBPC. Therefore, it is likely that the participation of a carrier-mediated transport in the absorption of CIPC may significantly contribute to the improved absorption of the prodrug over the parent drug.

Administration, Oral↗
PubMed1999

Identification of a flavivirus isolated from mosquitos in Chiang Mai Thailand.

A virus isolate, ThCAr105/92, from a pool of mosquitos, Culex tritaeniorhynchus, collected in Chiang Mai, Thailand in 1992, appeared to be a member of the genus Flavivirus of the family Flaviviridae, based on the reverse transcription polymerase chain reaction (RT-PCR) using flavivirus cross-reacting primer pairs, electron microscopic examination, and serological tests. However, RT-PCR using Japanese encephalitis (JE) virus-specific primers showed that the isolate was different from JE virus. Sucrose density gradient sedimentation of the virus replicated in C6/36 cells indicated that the virus is relatively unstable in the infected culture fluids at 37 degrees C. Antibody prepared against this virus and a virus seed for the isolate were tested by cross neutralization against a panel of flaviviruses and the results showed that the new isolate was a distinct subtype of Tembusu virus.

Animals↗
PubMed1998

The antithrombotic effect of potent bifunctional thrombin inhibitors based on hirudin sequence, P551 and P532, on He-Ne laser-induced thrombosis in rat mesenteric microvessels.

The antithrombotic effect of potent synthetic bifunctional non-substrate type thrombin inhibitors based on hirudin sequences, P551 and P532, on Helium-Neon laser-induced thrombosis was investigated in rat mesenteric microvessels and compared with other types of thrombin inhibitors. P551 and P532, when given intravenously, inhibited platelet-rich thrombus formation in both arterioles and venules in a dose-dependent manner. The inhibitory effect was maximal immediately after intravenous administration and persisted for 20-30 minutes in both arterioles and venules. The minimal effective doses of P551 and P532 were 1.0 mg/ kg (intravenously) in both. However, the time course of the antithrombotic effect was not in keeping with the inhibitory effect measured by an activated partial thromboplastin time and was similar to other types of inhibitors in spite of different half-lives. The current findings show that P551 and P532 had significant inhibitory effects on platelet-rich thrombus formation and suggest that these bifunctional thrombin inhibitors could be potent antithrombotic agents.

Animals↗
PubMed1998

Lack of renal secretion of carbenicillin in rats: poor affinity to the organic anion transporter at renal brush border membrane.

The renal secretion of carbenicillin (CBPC) was studied in rats. The results obtained in the in vivo study indicated very poor renal secretion of CBPC in rats, which was entirely different from those observed in humans and rabbits. In humans and rabbits, significant and stereoselective renal secretion of CBPC was observed in vivo. In order to verify the poor renal secretion of CBPC in rats, the transport characteristics of the organic anion transporters were studied in vitro using basolateral and brush border membrane vesicles. Transport of p-aminohippuric acid (PAH) into the basolateral membrane vesicles (BLMVs) was inhibited by CBPC, indicating that the organic anion transporter located at the BLM may have affinity to CBPC. In contrast, the transport of PAH into the brush border membrane vesicles (BBMVs) was not inhibited by CBPC, suggesting that the organic anion transporter located at the BBM may not have affinity to CBPC. Similar results were obtained for sulbenicillin (SBPC). Since CBPC and SBPC exist as di-anions at physiological pH, the organic anion transporter located at the rat renal BBM may not exhibit affinity to water-soluble di-anions, which in turn will result in poor renal secretion of these compounds.

Animals↗
PubMed1998

Stereoselective renal secretion of carbenicillin in rabbits: role of the organic anion transporter at the renal brush border membrane.

Stereoselectivity in the renal secretion of carbenicillin (CBPC) was studied in rabbits. Significant renal secretion of CBPC was observed in vivo, with the secretion of the S-epimer being greater than that of the R-epimer. Stereoselective transport of CBPC was further studied in vitro using basolateral and brush border membrane vesicles prepared from rabbit kidneys. The transport of CBPC by the organic anion transporter into the basolateral membrane vesicles (BLMV) was not stereoselective. In contrast, a distinct stereoselectivity was observed in the transport of CBPC by the organic anion transporter into the brush border membrane vesicles (BBMV), with the transport of the S-epimer being more favorable. Significant epimer-epimer interactions were also observed in the transport into BBMV. The stereoselectivity of the transport of CBPC was calculated from the kinetic parameters with consideration of epimer-epimer interactions and was similar to that observed in vivo. It was concluded that the observed stereoselectivity in the renal secretion of CBPC in vivo reflected that of transport via the organic anion transporter located at the brush border membrane.

Animals↗
PubMed1998

Comparisons of rice field mosquito (Diptera: Culicidae) abundance among areas with different agricultural practices in northern Thailand.

Adult mosquitoes were collected from 3 areas in northern Thailand with different availabilities of rice fields for larval habitats by using blacklight, truck, and pig-baited traps. Culex tritaeniorhynchus Giles and Culex gelidus Theobald were dominant in all samples. Significant study-area differences were found in light and truck trap collections for Cx. tritaeniorhynchus and Cx. gelidus, but not for Culex vishnui Theobald + Culex pseudovishnui Colless. In pig-baited sample area differences were significant only for Cx. gelidus. Adults of Culex fuscocephala Theobald were relatively rare, comprising only 0.6-7.9% of the total mosquitoes collected. When compared with the results from previous studies in the Chiangmai area, we conclude that Cx. fuscocephala has become a minor species and that changes in the mosquito fauna have occurred in northern Thailand.

Agriculture↗
PubMed1998

Dietary soy protein isolate, compared with casein, reduces atherosclerotic lesion area in apolipoprotein E-deficient mice.

The objective of this study was to compare the effects of dietary soy protein isolate and casein on atherosclerotic lesion development in apolipoprotein (apo) E-deficient mice. Male C57BL/6J apoE-deficient mice (9-10 wk old) in groups of 6-9 were used in a series of feeding studies. In the first experiment, mice were fed purified diets containing cholesterol (1 g/100 g) and cholate (0.25 g/100 g) for 6 wk; soy protein isolate or casein was used as the protein source. Although serum total cholesterol concentration did not differ between groups, the lesion area of the thoracic aorta in the soy protein isolate group was lower than that of the casein group (P < 0.01). In the second and third experiments, mice were fed the same purified diet as in Experiment 1, only without supplementation of cholesterol and cholate for 24 and 9 wk, respectively. In each of these two experiments, serum total cholesterol concentrations again did not differ between soy protein isolate- and casein-fed groups. Serum homocysteine concentrations did not differ between groups in Experiment 3. Dietary soy protein isolate, compared with casein, lowered the thoracic aorta lesion area (Experiment 2; P < 0.001) and the percentage of the aortic arch inner surface covered by lesions (P < 0.05). In the final experiment, mice were fed the cholesterol-free diets containing ethanol-extracted soy protein isolate or casein plus the soy protein ethanol extracts for 9 wk. There were no differences in serum total cholesterol concentration or thoracic aorta lesion areas between the two groups. These results indicate that the antiatherogenic effect of native soy protein isolate cannot be explained by its effect on serum lipids or homocysteine and suggest that both the protein component and the ethanol extracts of the soy protein isolate may contribute to the antiatherogenic effect of the native soy protein isolate.

Animals↗
PubMed1998

Effects of mannitol and glycerol on cerebral energy metabolism in gerbils.

OBJECTIVES: To evaluate the effects of infusion with hyperosmolar solutions, mannitol and glycerol on the recovery of cerebral energy metabolism during ischemia and reperfusion in the gerbil brain. MATERIALS AND METHODS: Sequential changes in cerebral energy metabolism following 90-min ischemia and up to 8 h after reperfusion were measured in 15 gerbils using 31P nuclear magnetic resonance (NMR) spectroscopy after 60-min infusion of 10% glycerol (0.5 g/kg; n=5), or 20% mannitol (1.0 g/kg; n=5), and compared with those gerbils receiving with saline (n=5). Gerbils were anesthetized by intraperitoneal injection of pentobarbital. Forebrain ischemia was induced by clipping of bilateral common carotid arteries for 90 min and reperfused. NMR spectroscopy was measured by a 6.34-Tesla JEOL spectrometer, before administration, 2, 4, 6, and 8 h after 90-min ischemia and reperfusion. Areas of inorganic phosphate (Pi), phosphocreatine (PCr), and beta-ATP peaks were measured to calculate parameters of cerebral energy metabolism, i.e., PCr/Pi and beta-ATP/Pi ratios. Intracellular pH (pHi) was calculated from chemical shifts of Pi relative to PCr. RESULTS: PHi was higher in the mannitol group than in the glycerol and saline groups (P<0.05) 2 h after reperfusion. PCr/Pi ratio was higher 2, 4, and 8 h after reperfusion (P<0.01, P<0.05, P<0.01) in the mannitol group; and 6 h after reperfusion (P<0.05) in the glycerol group; than in the saline group. Beta-ATP/Pi ratio was higher 2 and 8 h after reperfusion (P<0.05) in the glycerol group; and 2 h after reperfusion (P<0.01) in the mannitol group, than in the saline group. CONCLUSIONS: The mannitol group had improved pHi higher than the glycerol group 2 h after reperfusion (P<0.05), while the glycerol group had improved beta-ATP/Pi ratio higher than the mannitol group 6 h after reperfusion (P<0.05). Both mannitol and glycerol groups had improved parameters of cerebral energy metabolism during ischemia and up to 8 h after reperfusion in the gerbil brain.

Adenosine Triphosphate↗
PubMed1998

Can aggressive lipid lowering using low-density lipoprotein apheresis prevent restenosis after percutaneous transluminal coronary angioplasty in patients with normocholesterolemia?

We examined whether aggressive lipid lowering using low-density lipoprotein (LDL) apheresis could prevent restenosis after percutaneous transluminal coronary angioplasty (PTCA). Fifteen patients with 17 lesions underwent LDL apheresis once within a week before and after PTCA and thereafter every 2 or 3 weeks (apheresis group) for about 4 months. The control group consisted of 17 patients with 17 lesions. No patients received additional lipid lowering drugs after PTCA. In the apheresis group, the time interval means of the total and LDL cholesterol levels were significantly lower than those in the control group whereas no significant differences were found between the 2 groups regarding the mean percent diameter stenosis or minimal lumen diameter before and after PTCA and at follow-up. The restenosis rate was 29.4% in the apheresis group and 47.1% in the control group. The restenosis rate tended to be slightly lower in the apheresis group. The overall results, however, indicated that aggressive lipid lowering does not prevent restenosis.

Aged↗