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Biomedical subjects

Y Tsuda

Publications and source records attributed to Y Tsuda.

At least 109 records · Page 6Linked to original sources
PubMed1997

A novel method for induction and detection of anaphylactic reaction using the mouse abdominal wall (AW method).

We found that an antigen-specific anaphylaxis was induced by antigen challenge to the abdominal wall, ear auricle, or subcutaneous tissue in mice sensitized 9 days previously with antigen and adjuvant. The anaphylactic reaction was detected by vascular permeability at the injected site 7 minutes after challenge, which was the best time for estimation. A novel method (AW method) for induction and detection of the anaphylactic reaction in mice was established using the abdominal wall as the challenge site. This method could detect the anaphylactic response in mice 1 to 3 weeks after sensitization. The increase in vascular permeability was completely inhibited by administration of diphenhydramine.

Abdominal Muscles↗
PubMed1997

Degradation of a novel tripeptide, tert-butoxycarbonyl-Tyr-Leu-Val-CH2Cl, with inhibitory effect on human leukocyte elastase in aqueous solution and in biological fluids.

The stability of tert-butoxycarbonyl-Tyr-Leu-Val-CH2Cl (YLV) with inhibitory effect on human leukocyte elastase was investigated in aqueous solution, alpha-chymotrypsin solution and biological media. In all cases studied here, the degradation was observed as a pseudo-first order reaction. The half-life for the degradation of YLV in an aqueous solution of pH 7.4 at 37 degrees C was 35.9 h. YLV was most stable at about pH 3.8-5.8 and the effect of temperature was explained by the Arrhenius equation. The activation energies of the degradation in aqueous solutions at pH 2.0, 4.8, and 7.4 were 24.6, 22.1 and 23.4 kcal/mol, respectively. The degradation products in aqueous solution were analyzed by HPLC-MS and were estimated as Boc-Tyr-Leu-Val-CH2OH at pH 7.4 and H2N-Tyr-Leu-Val-CH2Cl at pH 2.0. In a bovine pancreas alpha-chymotrypsin solution at 37 degrees C, the half-life of YLV was 15 min at 25.6 micrograms/ml of alpha-chymotrypsin solution. In the rat plasma, the half-life of YLV was 42.4 min (YLV 26.7 micrograms/ml plasma), and in rat liver, lung and spleen homogenates, the degradation rate constants of YLV were 37.6, 10.3 and 23.5 times larger than that in plasma solution, respectively (all fluids containing 5 mg protein/ml). YLV was less stable than nafarelin acetate, secretin, adrenocorticotropic hormone (ACTH) and gonadorelin in an aqueous solution of pH 7.4.

Animals↗
PubMed1997

Acacia concinna saponins. I. Structures of prosapogenols, concinnosides A-F, isolated from the alkaline hydrolysate of the highly polar saponin fraction.

A highly polar saponin mixture from pods of Acacia concinna (Leguminosae) was hydrolyzed with alkali to yield five new triterpenoidal prosapogenols named concinnosides A (6), B (3), C (7), D (4), and E (8), together with four known glycosides, acaciaside, (2), julibroside A1 (10) julibroside A3 (9), albiziasaponin C (5), and their aglycone, acacic acid lactone (1). The structures of these new prosapogenols were elucidated based on spectroscopic means. A less polar saponin fraction from the pods gave spinasteryl glucoside and its dihydro derivative.

Acacia↗
PubMed1997

Synthesis and nematocidal activity of aralkyl- and aralkenylamides related to piperamide on second-stage larvae of Toxocara canis.

Seventy-nine aralkyl- and aralkenylamides related to piperamides were synthesized and their nematocidal activity against second-stage larvae of dog roundworm, Toxocara canis, was examined. The activity was greatly dependent on the alkyl chain length and the nature of the amine moiety, but was scarcely affected by the presence or absence of double bond(s) in the chain. The alkyl chain lengths which showed the strongest activity in a series of homologues were m = 11 for the pyrrolidine amides and m = 13 for the N-methylpiperazine amides. Although piperamides (3,4-methylenedioxyphenyl homologues) showed the strongest activity among the homologues tested, methoxy substituent(s) on the aromatic ring did not have much effect on the activity. However, conversion of the methoxy group to a hydroxy group greatly decreased the activity and shortened the chain length giving the strongest activity. Calculated log P values of non-phenolic aryl-piperamides fell in the range from 3.5 to 4.5, whereas those of hydroxyphenyl-piperamides were smaller, suggesting that different mechanisms are involved in the nematocidal activity of phenolic and non-phenolic compounds.

Amides↗
PubMed1997

Phorbol ester enhancement of IL-3-dependent proliferation of primitive hematopoietic progenitors of mice in culture.

Protein kinase C (PKC) is a Ca++- and phospholipid-dependent protein kinase activated by diacylglycerol that is either released from cell membranes in response to certain growth factors or mimicked by 12-O-tetradecanoyl phorbol-13-acetate (TPA). We studied the effects of TPA on interleukin-3 (IL-3)-dependent colony formation of mouse bone marrow cells from mice injected with 5-fluorouracil 2 days before examination in order to clarify the significance of PKC in the proliferation of primitive hematopoietic progenitors. Although TPA alone did not support colony formation, TPA in combination with IL-3 increased colony numbers from 1.5 to 2 times that formed with IL-3 and vehicle. TPA increased not only the granulocyte/macrophage colonies, but also the multilineage colonies. A sequential colony count showed that TPA, unlike IL-6, did not hasten the appearance of colonies. Because TPA enhanced IL-3-dependent colony formation derived from lineage-negative marrow cells obtained from mice that received 5-FU 2 days before, it is possible that it might act directly on primitive progenitors. Prolonged pretreatment of marrow cells with TPA prevented TPA-augmented colony growth. Calphostin C, a specific PKC inhibitor, and certain specific tyrosine kinase inhibitors, such as genistein and herbimycin A, abrogated the enhancing effects of TPA on IL-3-dependent colony formation. These data suggest that TPA had a direct effect on the primitive progenitors and enhanced IL-3-dependent colony formation via activation of PKC and certain tyrosine kinases.

Animals↗
PubMed1997

Chronic hemorheological effects of the calcium antagonist nilvadipine in essential hypertension.

Because blood viscosity is significantly raised in patients with essential hypertension (EH), the hemorheological effects of a 4-month chronic treatment with the calcium antagonist nilvadipine (FK 235, 5-isopropyl-3-methyl-2-cyano-1,4-dihydro-6-methyl-4- (m-nitrophenyl)-3,5-pyridinedicarboxylate, CAS 75530-68-6) on elevated blood viscosity was investigated prospectively in patients with EH, and compared with those in normotensive individuals of similar age. Hemorheological parameters were measured in 13 patients with EH (mean 63.7 years), before and 16.3 weeks (mean) after treatment with 8 mg nilvadipine, twice a day, following a 2-week placebo period, and in 14 normotensive individuals (mean 65.8 years). Whole blood viscosity of 45.0-562.5 s-1 shear rates and corrected blood viscosity of low (45.0 s-1) and high (225.0 s-1) shear rates at standardised hematocrit (Ht) of 45%, plasma viscosity, Ht, serum albumin, and plasma fibrinogen were measured before and after drug treatment and compared with those in normotensive individuals. Whole-blood and plasma viscosities were measured by cone-plate viscometer. Systolic and mean blood pressures (BPs), whole blood viscosities (at low and middle shear rates), corrected blood viscosity (Ht 45% at a low shear rate), and plasma viscosity were higher in patients with EH than in normotensive individuals before medication (p < 0.001 to p < 0.01). All these parameters decreased significantly after nilvadipine (p < 0.004 to p < 0.05). On the other hand, serum albumin and plasma fibrinogen were not altered significantly after nilvadipine. Ht decreased but not significantly after nilvadipine. Mean BP correlated with corrected blood viscosities at 112.5 s-1 and 225.0 s-1 (r = 0.491 p < 0.01 and r = 0.537 p < 0.005), while systolic BP did not correlate, before and after nilvadipine. Chronic treatment with calcium antagonist nilvadipine brought about significant reductions in BPs and rheological parameters of whole-blood viscosities at low and middle shear rates, corrected blood viscosity (Ht 45%) at a low shear rate, and plasma viscosity without changes in serum albumin and plasma fibrinogen levels, as compared with normotensive individuals. Significant linear correlations between values of mean BP and corrected blood viscosities before and after milvadipine show improved hemorheology in association with BP reduction in EH. Vasodilative effects of nilvadipine may have improved the blood rheology in patients with EH.

Blood Pressure↗
PubMed1996

Torsional rigidity of single actin filaments and actin-actin bond breaking force under torsion measured directly by in vitro micromanipulation.

Knowledge of the elastic properties of actin filaments is crucial for considering its role in muscle contraction, cellular motile events, and formation of cell shape. The stiffness of actin filaments in the directions of stretching and bending has been determined. In this study, we have directly determined the torsional rigidity and breaking force of single actin filaments by measuring the rotational Brownian motion and tensile strength using optical tweezers and microneedles, respectively. Rotational angular fluctuations of filaments supplied the torsional rigidity as (8.0 +/- 1.2) x 10(-26) Nm2. This value is similar to that deduced from the longitudinal rigidity, assuming the actin filament to be a homogeneous rod. The breaking force of the actin-actin bond was measured while twisting a filament through various angles using microneedles. The breaking force decreased greatly under twist, e.g., from 600-320 pN when filaments were turned through 90 degrees, independent of the rotational direction. Our results indicate that an actin filament exhibits comparable flexibility in the rotational and longitudinal directions, but breaks more easily under torsional load.

Actins↗
PubMed1996

Use of an active center-directed plasmin inhibitor elucidates the multiplicity of plasmin actions.

In our studies, designed to synthesize an active center-directed plasmin (PL) inhibitor, N-(4-aminomethylbenzoyl)-4-(3-picolyloxy)-L-phenylalanine n-hexylamide dihydrochloride (PASI-535) was found. We characterized PASI-535 and analyzed the actions of PL, comparing with those of PASI-535 and tranexamic acid (t-AMCHA). (1) PASI-535 strongly inhibited not only fibrinolysis (IC50: 2.9 x 10(-6) M) but also amidolysis (Ki value: 2.9 x 10(-6) M) and fibrinogenolysis (IC50: 4.5 x 10(-6) M) induced by PL. While t-AMCHA which strongly inhibited fibrinolysis (IC50: 6.0 x 10(-5) M), rarely inhibited amidolysis (Ki value: 4.0 x 10(-2) M) and fibrinogenolysis (IC50: 1.0 x 10(-2) M). (2) PL is able to liberate kinins by degrading kininogen. This kinin-generation by PL was inhibited by 2 x 10(-5) M PASI-535. However, it was little inhibited even by 1 x 10(-3) M t-AMCHA. (3) The inhibitory effect of PASI-535 and t-AMCHA on tumor growth was studied. In sarcoma-180 bearing mice, ascites retention and the increase of tumor cells were markedly suppressed by subcutaneous injection of PASI-535, either 30 mg/kg/day or 50 mg/kg/day, for 5 days, and the inhibitory effect was dose-dependent. Although t-AMCHA also reduced both ascites retention and the increase of tumor cells, it needed approximately 40 times (2 g/kg/day) the amount of PASI-535 to exert these effects. PASI-535 may be a useful tool in analyzing the multiplicity of PL actions. Moreover, PASI-535 can be used as an antifibrinolytic drug which has a mechanism of function different from that of t-AMCHA.

Amino Acid Sequence↗
PubMed1996

Synthesis and hypolipidemic activities of novel 2-[4-[diethoxyphosphoryl)methyl]phenyl]quinazolines and 4(3H)-quinazolinones.

The novel compound NO-1886, 4-[(diethoxyphosphoryl)methyl]-N-(4-bromo-2-cyanophenyl)-ben zamide, is a hypolipidemic agent, which appears to increase lipoprotein lipase activity in rats. Various analogs of NO-1886 were synthesized to study the structure-activity relationship of this hypolipidemic drug. A novel series of quinazolines and 4(3H)-quinazolinones were prepared by cyclization of NO-1886 derivatives. Derivatives bearing a 4-[(diethoxyphosphoryl)-methyl]phenyl] group at the 2-position were found to lower triglyceride and total cholesterol levels. In accord with the decrease in log P*, quinazolines and 4(3H)-quinazolinones showed good absorption and hypolipidemic activity. When the quinazolinone ring system is substituted at positions 6 and 7 with methoxy groups, increased hypolipidemic activity was observed. The highest hypolipidemic activity was observed when the 3-position was substituted by a methyl or benzyl group.

Animals↗
PubMed1996

Stereoselective binding of carbenicillin epimers to human serum albumin.

Binding of carbenicillin (CBPC) epimers to human serum albumin (HSA) was found to be stereoselective. Epimer-epimer interaction was also observed in the binding to HSA. There were at least three binding sites on HSA for CBPC epimers, one of which (stereoselective site) was more in favor of S-CBPC than R-CBPC. At the stereoselective site, the binding constant of S-CBPC was approximately 4-fold greater than that of R-CBPC. The affinities to other binding sites (non-stereoselective sites) were similar between the epimers, and the affinity of S-CBPC of the non-stereoselective sites was much smaller than that for the stereoselective site. R-CBPC and S-CBPC appeared to displace each other at all the binding sites, i.e., the binding of the epimers was competitive at the non-stereoselective sites as well as at the stereoselective site. By using site marker ligands, it was revealed that CBPC epimers may bind to Site I (warfarin binding site), but not to Site II (diazepam binding site). A binding model with an assumption of competitive interactions at all the binding sites simulated the binding characteristics of CBPC epimers fairly well.

Binding Sites↗
PubMed1996

Crystal structure of two new bifunctional nonsubstrate type thrombin inhibitors complexed with human alpha-thrombin.

The crystal structures of two new thrombin inhibitors, P498 and P500, complexed with human alpha-thrombin have been determined at 2.0 A resolution and refined to crystallographic R-factors of 0.170 and 0.169, respectively. These compounds, with picomolar binding constants, belong to a family of potent bifunctional inhibitors that bind thrombin at two remote sites: the active site and the fibrinogen recognition exosite (FRE). The inhibitors incorporate a nonsubstrate type active site binding fragment: Dansyl-Arg-(D)Pipecolic acid (Dns-Arg-(D)Pip), reminiscent of the active-site directed inhibitors MD-805 and MQPA, rendering them resistant to thrombin-induced hydrolysis. The FRE binding fragment of these inhibitors corresponds to the hirudin55-65 sequence. They differ in the chemical nature of the nonpeptidyl linker bridging these two functional activities. In both cases, the active site binding fragment is well defined in the electron density. The DnsH1, ArgH2, and (D)PipH3 groups occupy the S3, S1, and S2 subsites of thrombin, respectively, in a way similar to that observed in the thrombin-MQPA complexes. Binding in the active site of thrombin is characterized by numerous van der Waals contacts and ring-ring system interactions. Unlike in the substrate-like inhibitors, ArgH2 enters the S1 specificity pocket from the P2 position and adopts a bent conformation to make an hydrogen bond to the carboxylate of Asp189. In this noncanonical position, its carbonyl points away from the oxyanion hole, which is now occupied by well-ordered solvent molecules. The linkers fit in the groove extending from the active site to the FRE. The C-terminal fragments of both inhibitors bind in the same way as analogous FRE binding elements in previously described complexes.

Amino Acid Sequence↗
PubMed1996

Effects of pravastatin sodium and simvastatin on plasma fibrinogen level and blood rheology in type II hyperlipoproteinemia.

Elevated plasma fibrinogen level is known to progress atherosclerosis and to be one of the risk factors for the occurrence of cardiovascular diseases. The objective of this study is to evaluate the changes in plasma fibrinogen level and blood rheology in patients with type II hyperlipoproteinemia before and after random administrations of HMG-CoA (3-hydroxy-e-methylglutaryl-cocarboxylase-A) reductase inhibitors, pravastatin sodium and simvastatin, and compare with results in normal subjects. Of a total of 28 patients with type II primary hyperlipoproteinemia with > 230 mg/dl fasting total plasma cholesterol, 16 patients (mean, 59.7 years old) were administered 10-15 mg/day of pravastatin sodium for an average of 10.2 weeks, and 12 patients (mean, 62.0 years old) were administered 5-10 mg/day of simvastatin for an average of 13.9 weeks. Patients were evaluated before and after drug administration and results were compared with those of 16 normal subjects of similar age (mean, 56.9 years old). Blood viscosities were measured using a cone-plate viscometer (Biorheolizer, BRL-1000, Japan). The following were measured before and after drug administration: whole blood viscosity at shear rates of 75-375 s-1, corrected blood viscosity at low (112.5 s-1) and high (225.0 s-1) shear rates for the standard hematocrit of 45%, plasma viscosity, hematocrit, total protein, serum albumin, and plasma fibrinogen. Total cholesterol level was significantly decreased (from 270 to 225, mg/dl, mean values; P < 0.0007) an average of 10.2 weeks after start of pravastatin sodium administration. In addition to the reductions of whole blood viscosity, at every shear rate examined, corrected blood viscosity, and plasma viscosity, plasma fibrinogen levels were significantly decreased (from 354 to 309 mg/dl, mean values; P < 0.0007) after start of pravastatin sodium administration. Fibrinogen level and blood rheology were not significantly changed after start of simvastatin administration despite similar significant reductions in total cholesterol level (from 260 to 207 mg/dl, mean values; P < 0.0001) to those in the case of pravastatin sodium. From the results, we conclude that administration of pravastatin sodium, but not simvastatin, reduced the plasma fibrinogen level and blood viscosities to normal levels in type II hyperlipoproteinemic patients while both drugs reduced total cholesterol level. The hydrophilicity and a small binding capacity with plasma protein of pravastatin sodium may be responsible in part for the beneficial hemorheologic effects observed in the patients with type II hyperlipoproteinemia. Further investigations should be conducted to confirm the findings observed.

Acyl Coenzyme A↗
PubMed1996

Direct inhibition of the actomyosin motility by local anesthetics in vitro.

Using a recently developed in vitro motility assay, we have demonstrated that local anesthetics directly inhibit myosin-based movement of single actin filaments in a reversible dose-dependent manner. This is the first reported account of the actions of local anesthetics on purified proteins at the molecular level. In this study, two tertiary amine local anesthetics, lidocaine and tetracaine, were used. The inhibitory action of the local anesthetics on actomyosin sliding movement was pH dependent; the anesthetics were more potent at higher pH values, and this reaction was accompanied by an increased proportion of the uncharged form of the anesthetics. QX-314, a permanently charged derivative of lidocaine, had no effect on actomyosin sliding movement. These results indicate that the uncharged form of local anesthetics is predominantly responsible for the inhibition of actomyosin sliding movement. The local anesthetics inhibited sliding movement but hardly interfered with the binding of actin filaments to myosin on the surface or with actomyosin ATPase activity at low ionic strength. To characterize the actomyosin interaction in the presence of anesthetics, we measured the binding and breaking force of the actomyosin complex. The binding of actin filaments to myosin on the surface was not affected by lidocaine at low ionic strength. The breaking force, measured using optical tweezers, was approximately 1.5 pN per micron of an actin filament, which was much smaller than in rigor and isometric force. The binding and breaking force greatly decreased with increasing ionic strength, indicating that the remaining interaction is ionic in nature. The result suggests that the binding and ATPase of actomyosin are governed predominantly by ionic interaction, which is hardly affected by anesthetics; whereas the force generation requires hydrophobic interaction, which plays a major part of the strong binding and is blocked by anesthetics, in addition to the ionic interaction.

Actins↗
PubMed1996

Nimodipine improves brain energy metabolism and blood rheology during ischemia and reperfusion in the gerbil brain.

Whether nimodipine improves cerebral blood flow (CBF) and metabolism in cerebral ischemia remains a controversial issue. We investigated the effect of nimodipine on CBF, brain energy metabolism, using a laser-Doppler flowmeter and in vivo 31phosphorus nuclear magnetic resonance (31P NMR) spectroscopy, and blood rheology during forebrain ischemia and reperfusion in gerbils. Eighty-three adult gerbils received nimodipine (1 micrograms/kg/min), or an equal volume of the vehicle, or saline, over 60 min prior to a transient forebrain ischemia for 60 min. We measured sequential changes in phosphocreatine (PCr) / inorganic phosphate (Pi) ratio, beta-ATP/Pi ratio, and intracellular pH (pHi) during ischemia and reperfusion by 31P NMR spectroscopy, and the measurement of whole blood viscosity (WBV) at 60 min after reperfusion. CBF was measured continuously throughout the study by a laser-Doppler flowmeter. During forebrain ischemia, PCr/Pi and beta-ATP/Pi ratios were higher significantly in the nimodipine-treated group (p < 0.05 and 0.01) than in the vehicle- or saline-treated groups. During reperfusion, PCr/Pi and beta-ATP/Pi ratios recovered significantly only in the nimodipine-treated group (p < 0.05 and 0.01). The WBV at high shear rate (562.5 s-1) lowered significantly in the nimodipine-treated group (p < 0.05) compared with the vehicle- or saline-treated group. CBF was higher significantly only during administration of nimodipine in the nimodipine-treated group (p < 0.01) than other groups. Nimodipine improved brain energy metabolism and blood rheology during forebrain ischemia and reperfusion in the gerbil brain.

Animals↗
PubMed1996

MRI evidence of high signal intensity and temporomandibular arthralgia and relating pain. Does the high signal correlate to the pain?

In order to investigate the relationship between various temporomandibular joint (TMJ) pain levels and the detection of high signal intensity (joint effusion) on T2 weighted magnetic resonance imaging (MRI), 19 consecutive patients who complained of unilateral painful TMJ hypomobility (closed locking) were involved in this study. All patients were clinically examined in a routine manner, and all patients rated their pain levels by a visual analogue scale and eight pain questionnaire prior MRI study. T1 and T2 weighted MRI was taken in sagittal section at unilateral affected joint side. The presence or absence of a high signal intensity spot within the TMJ compartment were judged by three examiners. The high signal intensity was detected in 10 joints, but not in 9 joints. In between these two groups, the pain ratio was calculated and compared. The data showed that there was no significant statistical correlation between pain levels and the presence of high signals. This study disclosed that the MRI detection of high signal intensity in the closed locking TMJ did not directly relate to the presence of TMJ pain nor the increased pain level. These indicate the need of further larger studies.

Adolescent↗
PubMed1996

Duration threshold of induced hypertension on cerebral blood flow, energy metabolism, and edema after transient forebrain ischemia in gerbils.

We have investigated whether there is a duration threshold for the effects of phenylephrine-induced hypertension on CBF, brain energy metabolism, and cerebral parenchymal specific gravity (SG) following transient forebrain ischemia in gerbils. Sixty gerbils were randomly assigned to one of the four treatment groups: one control group and three groups subjected to an increase of 25 mm Hg in MABP induced by treatment, 30 min after reperfusion, with phenylephrine for 15 min, 30 min, or 60 min. The local CBF was measured continuously, and the SG was evaluated 120 min after reperfusion. Sequential changes in brain energy metabolism, as shown by the ratio of phosphocreatine to inorganic phosphate (Pi), the beta-ATP/Pi ratio, and intracellular pH, were also measured. The 15-min induced hypertension regimen was most suited to the recovery of brain energy metabolism, which was associated with an increase in local CBF and a decrease in cerebral edema. These results demonstrate that a suitable duration can be chosen to optimize the beneficial effects of phenylephrine-induced hypertension on ischemic brain injury following transient forebrain ischemia.

Animals↗
PubMed1996

Histologic study of living response to artificially synthesized hydroxyapatite implant: 1-year follow-up.

We implanted artificially synthesized hydroxyapatite spheres into the orbits of 13 rabbits after enucleation. The spheres were removed 1, 2, 3, 6, and 12 months after implantation and examined by light and scanning electron microscopy. Tissue breakdown and exposure of the artificially synthesized hydroxyapatite implants were not observed. Month after month, fibrovascular tissues gradually invaded the pores of the artificially synthesized hydroxyapatite spheres deeper and deeper. Although the hydroxyapatite we used was completely artificially synthesized, we observed a mild foreign-body reaction around the artificially synthesized hydroxyapatite spheres. After 12 months, however, relief of the foreign-body reaction had occurred. Hydroxyapatite spheres for orbital implants after enucleation without scleral enveloping are appropriate.

Animals↗