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Biomedical subjects

Y Tsuda

Publications and source records attributed to Y Tsuda.

At least 37 records · Page 2Linked to original sources
PubMed2001

Stereoselective binding and degradation of sulbenicillin in the presence of human serum albumin.

Binding of sulbenicillin (SBPC) isomers to human serum albumin (HSA) was stereoselective. There were at least two classes of binding sites on HSA for SBPC isomers. At the stereoselective high affinity site, binding was in favor of R-SBPC, the binding constant of R-SBPC being approximately 2.3-fold greater than that of S-SBPC. By using site marker ligands, it was revealed that the stereoselective site was Site I (warfarin binding site). Affinity for the low affinity (nonstereoselective) site was similar for the diastereomers, approximately 7--30-fold lower than for the stereoselective site. R-SBPC and S-SBPC appeared to displace each other competitively at both binding sites. On the other hand, R-SBPC was degraded much faster than S-SBPC in the presence of HSA, with a degradation rate constant approximately 7-fold greater for R-SBPC than for S-SBPC. The degradation of R-SBPC was inhibited in the presence of warfarin and dependent on the concentration of R-SBPC bound to Site I. The results demonstrate that Site I is responsible for the stereoselective degradation.

Anti-Bacterial Agents↗
PubMed2001

Shift work modifies the circadian patterns of heart rate variability in nurses.

OBJECTIVE: The influence of shifting the work-sleep cycle on the circadian rhythm of cardiac autonomic activity was investigated by the spectral analysis of heart rate variability (HRV). METHODS: The subjects were 10 healthy Japanese female nurses aged 33+/-3 (S.D.) years. The subjects underwent ambulatory 24-h electrocardiogram (ECG) recordings on the days of day shift (working from 08:00 to 17:00 h) and night shift (working from 21:40 to 08:40 h). Variables of the frequency domain of HRV were calculated for three activity states (work, awake but not working, and sleep). RESULTS: The mean values of HRV variables over 24 h were not different between day shift and night shift. For both shifts, variables related to the sympathetic control (low frequency component in normalized units and low/high frequency component ratio) were the largest during the work period and the smallest during the sleep period, while an opposite order was present for variables related to the vagal control (high frequency component in absolute value and normalized units). HRV variables in each activity state were not different between the two shifts. CONCLUSIONS: The circadian rhythm of cardiac autonomic activity is largely modified by the level of physical activity regardless of the clock hour, which may have clinical implications when studying the circadian fluctuations of the onset of cardiovascular disease in shift workers.

Adult↗
PubMed2001

Binding diversity of a noncovalent-type low-molecular-weight serine protease inhibitor and function of a catalytic water molecule: X-ray crystal structure of PKSI-527--inhibited trypsin.

PKSI-527 is a noncovalent-type low-molecular-weight inhibitor. The X-ray crystal structure of the trypsin-PKSI-527 complex revealed a binding mode (Form II) different from the previously reported one (Form I) [Nakamura, M. et al. (1995) Biochem. Biophys. Res. Commun. 213, 583--587]. In contrast to the previous case, the electron density of the inhibitor revealed the whole structure clearly. Each structural part of the inhibitor in Forms I and II was differently located at the active site, although the modes of binding of the terminal amino group to the Asp189 carboxyl group were similar. This binding diversity, which is a characteristic of the noncovalent-type low-molecular-weight inhibitor, provides a suitable example for estimating the possible mechanism toward the enzymatic inhibition, together with the structural basis necessary for a specific inhibitor. The mode of binding in Form II reflects the inhibitor-specific situation and is in contrast with the substrate-mimetic binding mode for Form I. Based on the generally accepted catalytic mechanism for serine protease, we propose that a water molecule located at the catalytic site plays an important role in blocking the catalytic function of the reactive Ser193 OH group.

Animals↗
PubMed2001

Effect of cicletanine on the nitric oxide pathway in human umbilical vein endothelial cells.

The purpose of this study was to evaluate the effects of cicletanine, a slightly diuretic antihypertensive drug, on human vascular endothelial cells with regard to nitric oxide, intracellular calcium concentration ([Ca2+]i), cyclic nucleotide, inositol 1,4,5-trisphosphate (IP3), and prostacyclin generation. Primary cultured human umbilical vein endothelial cells were used in this study. [Ca2+]i was measured by fura-2/AM. Cyclic adenosine monophosphate (AMP), cyclic guanosine monophosphate (GMP), IP3, and prostacyclin were measured by radioimmunoassay. Nitric oxide was measured by the Griess method. Cicletanine had no effect on [Ca2+]i. Cicletanine (10(-6)-10(-4) M) increased cyclic GMP but decreased prostacyclin generation. Cicletanine had no stimulating effect on cyclic AMP or IP3 generation. IP3 increased 45Ca release from storage sites. Cicletanine decreased prostacyclin generation via increase in cyclic GMP. Cicletanine had no stimulating effect on nitrogen oxides for 2 h after incubation but increased it after 3-24 h. Pretreatment with L-N(G)-monomethyl-arginine (L-NMMA) prevented this increase. The inhibitory effect of L-NMMA was prevented by pretreatment with L-arginine. These results indicate that nitric oxide and cyclic GMP may contribute to the antihypertensive action of cicletanine.

Antihypertensive Agents↗
PubMed2001

Isolation of plasma kallikrein by high efficiency affinity chromatography and its characterization.

We established a simple method for the purification of human plasma kallikrein (PK) by affinity chromatography and characterized it by analytical reverse phase-HPLC and Time of Flight Mass Spectroscopy (TOF-MS). The affinity resin (PKSI-Toyopearl) was synthesized using a selective synthetic inhibitor of plasma kallikrein (PKSI-527) as a ligand. The resin was found to have the highest efficiency in PK purification when the coupling ratio of PKSI-527 per resin was 9-14 micromol/g. PK was purified 466-fold with a yield of 83% from acetone-activated human plasma by affinity chromatography. The purity of PK thus obtained was confirmed by reverse phase-HPLC with a linear gradient of acetonitrile. The molecular weight of the purified PK was determined to be 86,151 by TOF-MS.

Chromatography, Affinity↗
PubMed2001

Thio-sugars. IV. Synthesis of carbohydrate 1,3-glycol (six-membered) thionocarbonates and their attempted O-S rearrangement.

Four six-membered cyclic thionocarbonates (two sec-sec and two prim-sec) were prepared and their radical-promoted O-S rearrangement reaction was examined. The results revealed that the reaction in six-membered rings is difficult compared with the simple rearrangement in five-membered rings. In the course of syntheses of the substrates, interesting acyl migration during the stannylation process occurred.

Acylation↗
PubMed2001

Structure-inhibitory activity relationship of plasmin and plasma kallikrein inhibitors.

Based on the structure of Tra-Tyr(O-Pic)-octylamide, a portion of the octylamine was replaced with moieties bearing hydrophobic, basic or acidic groups. Replacement of the C-terminal residue with a moiety bearing a hydrophobic group gave the proper affinity of the inhibitor to both plasmin (PL) and plasma kallikrein (PK). While addition of a basic residue did not improve the affinity of the inhibitor, a carboxylic acid attached to the phenyl ring increased the PK selectivity of the inhibitor.

Amines↗
PubMed2001

Movement of Aedes aegypti (Diptera: Culicidae) released in a small isolated village on Hainan Island, China.

A mark-release-recapture experiment was conducted in a small isolated village on Hainan Island, China, to examine the dispersal and movement of adult Aedes aegypti (L.). Two cohorts of mosquitoes marked with uniquely colored fluorescent dye were released at two different sites and recaptured for 6 d at every house in the village using human bait collections. The distribution pattern of houses around release site affected dispersal. The recapture rate of females released at the center of the village was higher (3.49%) than females released at the edge of the village (2.47%). The average day of recapture differed significantly between sexes, but not cohorts. The average day of recapture of females and males released at the center was 2.5 and 1.54 d, respectively. The total number of mosquitoes recaptured was the greatest at premises near the release site, and decreased at a constant rate of 0.43-0.48 with increasing distance from the release site. The proportion of nulliparous females decreased during the first 4 d and proportion of females with developing or mature ovaries increased during the latter half of the experiment. The daily survival rate for females and males released at the center of the village was estimated by log-regression to be 0.763 and 0.52, respectively.

Aedes↗
PubMed2001

Involvement of protein kinase C-epsilon in signal transduction of thrombopoietin in enhancement of interleukin-3-dependent proliferation of primitive hematopoietic progenitors.

We studied the effect of thrombopoietin (TPO) on interleukin-3 (IL-3)-dependent bone marrow cell colony formation of mice to clarify the role of protein kinase C (PKC) in the signal transduction of TPO for the proliferation of primitive hematopoietic progenitors. TPO alone hardly yielded colonies. However, TPO in combination with IL-3 increased colony numbers synergistically from 2- to 4-fold, compared with those supported by IL-3 alone. Serial observation of colony development showed that TPO may hasten the appearance of colonies by shortening the dormant period (G(0)) of primitive progenitors. Immunocytochemical studies on PKC isoforms in progenitor cells stimulated with TPO have revealed that the expression pattern of PKC-epsilon is changed, but not that of PKC-alpha, -beta, -gamma, -delta, or -zeta. Selective PKC inhibitors, such as calphostin C and GF 109203X, and PKC-epsilon-specific translocation inhibitor peptide abrogated the enhancing effect of TPO on IL-3-dependent colony formation and the changes in the intracellular expression pattern of PKC-epsilon. These data taken together suggest that TPO has a direct effect on primitive progenitors and enhances IL-3-dependent colony formation, at least partly through the activation of PKC-epsilon.

Animals↗
PubMed2001

[Standard values of inter-inner canthal, inter-outer canthal, and inter-pupillary distances in normal Japanese infants and children].

UNLABELLED: PURPOSE AND MATERIALS: We studied inter-inner canthal distance(DIC), inter-outer canthal distance (DOC), and inter-pupillary distance (PD) in 1,006 normal Japanese infants and children to establish the normal ratio of DIC/PD and DOC/DIC for the diagnosis of congenital anomalies such as Waardenburg syndrome. RESULTS: DIC, DOC, and PD increased significantly from one month after birth to 12 years of age. DIC and DOC were stable but PD increased from 13 years of age to 15 years of age in junior high school. The DIC/PD and DOC/DIC averages were 0.61 and 2.73, respectively, one month after birth and 0.63 and 2.69 at three months after birth. On the other hand, DIC/PD and DOC/DIC were stable at 0.55-0.59 and 2.45 from 8 to 15 years of age. CONCLUSION: Since there have been no reports on standard values of DIC, DOC and PD in infants, we established the standard values in this study. These values are expected to be very useful in the diagnosis of neural crest cell migration anomalies, such as Waardenburg syndrome.

Adolescent↗
PubMed2001

Evidence for a new sibling species of Anopheles minimus from the Ryukyu Archipelago, Japan.

The Anopheles minimus complex is known to comprise at least 2 sibling species (A and C) in Thailand and Vietnam. This study investigated the specific status of An. minimus on Ishigaki Island, the Ryukyu Archipelago, Japan using morphological and genetic analyses. Morphological studies revealed that almost all (99.5%) of the adult mosquitoes are characterized by the humeral pale spot on the costa of their wings, a character that partially differentiates species A and C elsewhere. A high frequency (81.4%) have a pale fringe spot at the tip of vein 1A, a character rarely observed in other An. minimus populations. Significant seasonal variation in the size of wild An. minimus mosquitoes on the island was observed, with the largest size in the winter. Scanning micrographs of the cibarial armature of females from Ishigaki Island revealed that over 90% had cone filaments clearly differing in shape from those of species A or C. The Giemsa-stained metaphase karyotypes of larval brain cells were somewhat similar to those of species A, with a few exceptions, but were very different from those reported for species C. Crossing experiments between species A (CM strain) from Thailand and the progeny of An. minimus from Ishigaki Island (ISG strain) revealed postzygotic genetic incompatibility, although no prezygotic isolation. Hybrid progeny were only obtained from CM female x ISG male. F2 hybrid progeny were not obtained, since the hybrid males were sterile or almost sterile with atrophied testes or abnormal spermatozoa, although the polytene chromosomes of hybrid larvae showed synapsis. The hybrid females backcrossed with either CM or ISG males laid eggs with significantly lowered fertility and viability. The sequence for the D3 region of the 28S gene of ribosomal DNA of the ISG strain differed from those of species A and C. In addition, sequence data from Vietnamese mosquitoes suggest that the An. minimus complex may contain additional species. The morphological, cytogenetic, molecular, and hybridization evidence together suggest the existence of another sibling species of the An. minimus complex on Ishigaki Island, which is provisionally designated An. minimus species E.

Animals↗
PubMed2001

[Evaluation of a combination chemotherapy with nedaplatin and 5-FU for oral cancers].

Nedaplatin (cis-diammine-glycolato platinum: CDGP) is a platinum compound with a molecular weight of 303.18 that was recently developed in Japan. There have been reports of the antineoplastic effects of Nedaplatin on cancers in the cranio-cervical region, lung, esophagus, urinary bladder, testis, ovary, and uterus. In this study, we performed combined therapy of CDGP and fluorouracil (5-FU) for 8 patients with oral cancers, and evaluated the results to elucidate the clinical effect and adverse side effects. The subjects were 8 patients with squamous cell carcinoma (5 males and 3 females aged 33-65 years). The primary carcinoma regions were the tongue in 5 patients, oral floor in 2 patients, and mandibular gingiva in 1 patient. The T-classification was T2 in 6 patients and T4 in 2 patients, and the clinical staging was Stage II in 5 patients, Stage III in 1 patient and Stage IV in 2 patients. We first administered 700 mg/m2 5-FU per day from day 1 to day 5 (total dose 3,500 mg/m2), then 90 mg/m2 CDGP on day 5. The clinical effect was evaluated as a partial response in all cases, showing a 100% success rate. The histopathological findings of resected tumors were evaluated by Ohboshi and Shimozato's classification. One patient was Grade IIA, 5 patients Grade IIB, and 2 patients Grade III. The adverse side effects were slight myelotoxicity, gagging, nausea, alopecia, and stomatitis less than Grade II. Although the oral cancers in this study were extroverted superficial ulcerative cancers, and the number of patients was low at 8, this combined therapy is considered useful and worth evaluating in further accumulated cases.

Adult↗
PubMed2000

Inhibitory effect of various thrombin inhibitors on shear-induced platelet function and dynamic coagulation.

We assessed the effects of active site-directed, fibrinogen recognition exosite (FRE)-directed and bifunctional thrombin inhibitors, on shear-induced platelet reactivity (adhesion/aggregation) and dynamic coagulation (coagulation of flowing blood). An in vitro test for shear-induced haemostatic plug formation and dynamic coagulation (haemostatometry) was employed using non-anticoagulated rat blood. The active site-directed inhibitors (argatroban, P891, P899) caused inhibition of platelet reactivity and coagulation at 1-, 100- and 100-microM concentrations, respectively. Bifunctional inhibitors (P553, P1053) exerted inhibitory effects at 0.1 microM. A dimeric bifunctional inhibitor P824 caused significant inhibition at 1 microM. The FRE-directed inhibitor (P960) inhibited shear-induced platelet reactivity at 10 microM but the dynamic coagulation at 1 microM. Combination of active site-directed argatroban and FRE-directed P960 did not show any synergistic effect. The most potent inhibition was observed in monomeric bifunctional inhibitors. The inhibitory effects were compared with the K(i) values against human thrombin and with the IC(50) values against fibrin clot formation. The minimum effective concentrations on shear-induced platelet reactivity and dynamic coagulation were comparable with the IC(50) values, but not with the K(i) values.

Animals↗
PubMed2000

Development of plasmin and plasma kallikrein selective inhibitors and their effect on M1 (melanoma) and HT29 cell lines.

trans-4-Aminomethylcyclohexanecarbonyl-Tyr(O-Pic)-octylamide (YO-2) inhibited plasmin (PL) selectively, while trans-4-aminomethylcyclohexanecarbonyl-Phe-4-carboxymethylanili de (YO-1) inhibited plasma kallikrein (PK). YO-2 induced apoptosis of M1 (melanoma) cell line and HT29 colon carcinoma cells during 24 h through activation of caspase-3, while YO-1 did not affect either cell line even during 48 h.

Antineoplastic Agents↗
PubMed2000

Synthesis of stereoisomeric analogues of endomorphin-2, H-Tyr-Pro-Phe-Phe-NH(2), and examination of their opioid receptor binding activities and solution conformation.

All sixteen stereoisomeric analogues of endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH(2)) were synthesized by Fmoc-strategy using solid phase methods. Although synthetic endomorphin-2 exhibited similar mu- and delta-opioid receptor-binding activity to the natural compound, endomorphin-2 analogues containing d-amino acid isomers exhibited lower interaction with mu-receptors depending on the particular combination. The data clearly indicated that the three dimensional structure of endomorphin-2 with the natural l-configuration was the most suitable for binding within the mu receptor, but specific residues are important for activity. Circular dichroism studies verified that changes in chirality of amino acids in the endomorphin-2 sequence resulted in structural conformation. These alterations significantly reduced the specificity for mu-receptor-binding sites.

Animals↗
PubMed2000

Amino acids and peptides. LVII. Synthetic peptide with a sequence of ribonuclease from Sulfolobus solfataricus, SSR(1-62), does not function as an RNase.

The 62 residue peptide, SSR(1-62), whose sequence corresponds to that of ribonuclease (RNase) from Sulfolobus solfataricus, and its related peptides, SSR(1-22) and SSR(10-62), were chemically synthesized and their RNase activity and DNA-binding activity were examined. The RNase activity assay using yeast RNA or tRNA(fMet) as substrate showed that the synthetic peptide SSR(1-62) did not hydrolyze yeast RNA or tRNA(fMet). These data were not consistent with previous reports that both the native peptide isolated from S. solfataricus [Fusi et al. (1993) Eur. J. Biochem. 211, 305-311] and the recombinant peptide expressed in Escherichia coli [Fusi et al. (1995) Gene 154, 99-103] were able to hydrolyze tRNA(fMet). However, the synthetic SSR(1-62) exhibited DNA-binding activity. In the presence of synthetic SSR(1-62), the cleavage of DNA (plasmid pUCRh2-4) by restriction endonuclease (EcoRI) was not observed, suggesting that synthetic SSR(1-62) bound to DNA protected DNA from its enzymatic digestion. Neither SSR(1-22) nor SSR(10-62) prevented DNA from being cleaved by a restriction enzyme. These findings strongly suggest the importance of not only the N-terminal region of SSR(1-62) but also the C-terminal region for DNA-binding. Circular dichroism spectroscopy of synthetic SSR(1-62) indicated a beta-sheet conformation, in contrast with synthetic SSR(1-22), which exhibited an unordered conformation.

Amino Acid Sequence↗
PubMed2000

Adult onset Still's disease with hemophagocytic syndrome and severe liver dysfunction.

We report the case of a 55-year-old Japanese woman with adult onset Still's disease in whom hemophagocytic syndrome and severe liver dysfunction developed. High serum levels of ferritin, macrophage colony stimulating factor and interferon-gamma, which imply the presence of hemophagocytic syndrome, were detected. It is known that hemophagocytic syndrome is associated with adult onset Still's disease. In our case, many markedly swollen Kupffer cells with phagocytized red blood cells were found in the liver, as well as macrophages in the bone marrow and spleen. Accordingly, we believe that severe liver dysfunction in this case may have been related to hypercytokinemia due to hemophagocytic syndrome.

Journal Article↗