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Biomedical subjects

Y Shin

Publications and source records attributed to Y Shin.

At least 73 records · Page 4Linked to original sources
PubMed1998

Rhodocytin, a functional novel platelet agonist belonging to the heterodimeric C-type lectin family, induces platelet aggregation independently of glycoprotein Ib.

We isolated and characterized a functionally novel platelet agonist, designated as rhodocytin, from the Calloselasma rhodostoma venom. Rhodocytin was a disulfide-linked heterodimer consisting of 18- and 15-kDa subunits. The respective N-terminal amino acid sequences of both subunits were homologous to each other and to those of the carbohydrate-recognition domains (CRD) of C-type lectins. Rhodocytin alone induced platelet aggregation. Platelet agonists and antagonists constructed with CRD-like subunits from snake venoms bind to glycoprotein Ib directly or indirectly. However, rhodocytin induced platelet aggregation not by binding to glycoprotein Ib, because rhodocytin-induced platelet aggregation was not influenced by echicetin, a glycoprotein Ib-binding protein, that completely inhibits platelet agglutination by bovine von Willebrand factor. These findings indicate that rhodocytin is a novel protein structurally related to heterodimers of CRD-like subunits, but functionally distinct from venom proteins that induce platelet aggregation via glycoprotein Ib.

Amino Acid Sequence↗
PubMed1998

Discovery of LB30057, a benzamidrazone-based selective oral thrombin inhibitor.

Systematic variation of the so-called P-pocket moiety of benzamidrazone-based selective thrombin inhibitors led to the discovery of LB30057. It is potent (Ki = 0.38 nM for human thrombin), selective (Ki = 3290 nM for bovine trypsin), and orally bioavailable (58% oral bioavailability in dogs). LB30057 was efficacious in thrombosis animal models.

Animals↗
PubMed1998

Photoaffinity labeling of D1 and D5 dopamine receptors.

Although human D1 and D5 dopamine receptors are encoded by distinct genes and share only 50% sequence homology at the amino acid level, their pharmacological properties are identical. Using a selective D1 receptor photoaffinity radioligand, (+/-)-7-[125I]iodo-8-hydroxy-3-methyl-1-(4-azidophenyl)-2,3,4,5-tetrahyd ro-1H-3-benzazepine ([125I]MAB), we have further probed the molecular properties of these receptors in transfected GH4C1 rat pituitary cells. Under reversible, non-covalent binding conditions, [125I]MAB bound to both the D1 and the D5 receptors with identical affinities, dopaminergic selectivity and stereospecificity. Upon photoactivation of the bound [125I]MAB, the label was incorporated into a approximately 64,000 mol. wt protein corresponding to the D1 dopamine receptor. However, there was no specific photoincorporation of the ligand observed in D5 receptors. The lack of [125I]MAB photolabeling of D5 receptors was independent of the cell line chosen, since similar results were obtained using other transfected cells. The data suggest that although both D1 and D5 receptors share structurally similar binding sites, the protein domains around the sites are different. Thus, although there are currently no specific compounds which bind preferentially to D1 or D5 receptors, these receptors can be distinguished from one another by the inability of [125I]MAB to photolabel D5, but not D1, receptors. Such selective targeting of a specific receptor may be useful in understanding the functional importance and/or interaction between closely related members of the same receptor family when co-expressed in the same cell.

Animals↗
PubMed1998

Clinical course of atopic dermatitis in Japanese patients.

We conducted a questionnaire study of 117 patients, who had first consulted the Department of Dermatology Kumamoto University Hospital 20 or 30 years ago, regarding the clinical course of atopic dermatitis (AD). Forty-one patients responded to the questionnaire. Seventeen patients (41.4%) had recovered and 24 patients (58.6%) still had AD. The AD had resolved in 12 of 13 (92.2%) with mild disease severity, four of 18 (22.2%) with moderate severity and one of ten (10%) with severe disease. The outcome was significantly better in the mild group than in the moderate or severe group (chi2=15.5, P=0.0008/chi2=14.8, P=0.00012, respectively). The resolution of the disease was not correlated with the sex of patient, age at onset, period of disease or family history.

Adolescent↗
PubMed1998

Structural modification of an orally active thrombin inhibitor, LB30057: replacement of the D-pocket-binding naphthyl moiety.

An amidrazonophenylalanine derivative LB30057 (2) was identified as a potent (Ki = 0.38 nM), selective, and orally active thrombin inhibitor. As a continuation of studies into benzamidrazone-based thrombin inhibitors, we have structurally modified compound 2 by replacing the naphthyl group with a variety of hydrophobic moieties. This study led to discovery of several compounds with significantly enhanced potency in thrombin inhibition without sacrificing selectivity against trypsin and oral absorption. The highest activity was obtained with compound 23 (Ki = 0.045 nM).

Administration, Oral↗
PubMed1998

Prevalence of lower urinary tract symptoms in Korean men in a community-based study.

OBJECTIVE: The prevalence of lower urinary tract symptoms was determined in Korean men aged 50 and over. METHODS: A community-based, epidemiologic study was performed in Yonchon County, Korea. The Korean version of the International Prostate Symptom Score (I-PSS) was used to assess the severity of urinary symptoms in a representative sample of 514 men. RESULTS: Nocturia and weak stream were the most prevalent symptoms and urgency was the least. Overall, 23.2% of the men were moderately to severely symptomatic: 17.7% in the age group of 50-59 years, 23.3% in that of 60-69 years and 35.3% in that of 70 years and over. The proportion of severely symptomatic men approximately doubled with each decade of age. The 'quality of life' score showed a high correlation with the I-PSS. Our estimation indicated that in 1995 approximately 800,000 Korean men had moderate to severe lower urinary tract symptoms that were likely to be associated with benign prostatic hyperplasia. CONCLUSIONS: The prevalence of moderate to severe lower urinary tract symptoms in Korean men is substantially similar to that in Caucasians.

Aged↗
PubMed1997

Loperamide: a positive modulator for store-operated calcium channels?

The depletion of inositol trisphosphate-sensitive intracellular pools of calcium causes activation of store-operated calcium (SOC) channels. Loperamide at 10-30 microM has no effect on intracellular calcium levels alone, but augments calcium levels in cultured cells when SOC channels have been activated. In HL-60 leukemic cells, the apparent positive modulatory effect of loperamide on SOC channels occurs when these channels have been activated after ATP, thapsigargin, or ionomycin-elicited depletion of calcium from intracellular storage sites. Loperamide has no effect when levels of intracellular calcium are elevated through a mechanism not involving SOC channels by using sphingosine. Loperamide caused augmentation of intracellular calcium levels after activation of SOC channels in NIH 3T3 fibroblasts, astrocytoma 1321N cells, smooth muscle DDT-MF2 cells, RBL-2H3 mast cells, and pituitary GH4C1 cells. Only in astrocytoma cells did loperamide cause an elevation in intracellular calcium in the absence of activation of SOC channels. The augmentation of intracellular calcium elicited by loperamide in cultured cells was dependent on extracellular calcium and was somewhat resistant to agents (SKF 96365, miconazole, clotrimazole, nitrendipine, and trifluoperazine) that in the absence of loperamide effectively blocked SOC channels. It appears that loperamide augments influx of calcium through activated SOC channels.

3T3 Cells↗
PubMed1997

Escherichia coli F1-ATPase subunit interactions: beta and gamma subunit peptides inhibit in vitro reconstitution of the active alpha beta gamma complex.

For biochemical analysis of subunit interactions in the proton-translocating ATPase, a new approach with in vitro reconstitution of the Escherichia coli alpha beta gamma complex and the peptides derived from the subunits was established. Various portions of the beta or gamma subunits were used for in vitro reconstitution of the alpha beta gamma complex from the purified subunits. For the beta subunits, peptides corresponding to residues 226-459, 254-459, and 226-365 inhibited reconstitution, while those corresponding to residues 1-105, 1-146, and 295-459 did not. For the gamma subunits, peptides corresponding to residues 1-192 and 74-286 exhibited inhibitory effect on reconstitution, but the peptide containing residues 191-286 did not. Only inhibitory peptides blocked the assembly of the alpha beta gamma complex which was detected by nondenaturing polyacrylamide gel electrophoresis. These inhibitory peptides bound to the alpha or beta subunit on the filter, but the noninhibitory peptides did not. These results suggested that regions beta 254-294 and gamma 74-190 have sequences important for subunit interactions which interfered with those in the reconstitution mixtures. Based on comparison between X-ray crystallographic data of bovine alpha beta gamma complex and the present results, we discussed here the significance of the biochemical approach adopted in this study.

Circular Dichroism↗
PubMed1997

Screening for galactosaemia in Greece.

Galactosaemia appears to be one of the most appropriate disorders for routine newborn screening as almost normal outcome can be achieved in most of the identified cases. Galactose and galactose-1-phosphate were determined using Guthrie cards in a commercial kit based on a colorimetric microassay. Among 199,642 newborns, nine cases with classic galactosaemia, three with epimerase deficiency, six with compound Duarte2/heterozygotes for galactosaemia and four with compound2 Duarte homozygosity were found. Even though the number found among the screened neonates is small because it is such a rare disease, our results indicate one of the highest frequencies of the disease ever reported.

Age Factors↗
PubMed1997

A high-risk group for prostatism: a population-based epidemiological study in Korea.

OBJECTIVE: To evaluate the effect of sociodemographic, dietary and physical factors on prostatism in Korean men aged 50 and over. SUBJECTS AND METHODS: A community-based cross-sectional epidemiological study was performed in Yonchon County, Korea. The Korean version of the International Prostate Symptom Score (IPSS) was used to assess the severity of prostatism. Data on occupation, marital status, education, smoking habits, alcohol intake, daily consumption of nutrients, body mass index, abdominal circumference, waist-to-hip ratio, blood pressure, serum glucose, cholesterol, triglyceride and high-density lipoprotein (HDL) levels were analysed. The age-adjusted relative risk of these factors was calculated for moderate to severe prostatism (IPSS > or = 8). A multivariate analysis of all significant factors was performed to examine the joint effect of risk factors. RESULTS: Of 514 subjects, 119 (23.2%) had moderate to severe prostatism, the risk for which was related to age and alcohol consumption; waist-to-hip ratio (which represents the degree of abdominal obesity) and the serum level of HDL showed a biphasic association with prostatism in the multivariate analysis. CONCLUSION: In addition to previously reported risk factors, these data suggest that there might be an association between the development of prostatism and abnormal lipid metabolism.

Age Factors↗
PubMed1997

Tissue reactions to various percutaneous materials with different surface properties and structures.

Tissue responses to various percutaneous materials with different surface properties and structures were investigated. Dense hydroxyapatite (HA), tricalcium phosphate (TCP), glassy carbon (GC), and 2 types of porous HA were used. Cutaneous and subcutaneous tissues were tightly attached to the surface of the penetrating portion of an HA percutaneous device (PD). Neither bacterial infection nor serious epidermal downgrowth were observed in the area surrounding the shaft of the HA-PD. At the margin of the epidermis, fibroblasts and collagen fibrils of fibrous connective tissue were well oriented and formed perpendicular to the shaft. The tissue response to the TCP was mild and nearly the same as that to the HA. The GC induced serious epidermal downgrowth and inflammatory cell infiltration. In contrast to dense HA-PD, the insertion of both types of porous HA-PDs, 1 with a spongy structure and 1 with close pores was followed by acute infection within 1 month. Based upon these results, it was concluded that the dense HA was the best percutaneous material of those tested.

Animals↗
PubMed1996

Spiropyrrolizidines: a new class of blockers of nicotinic receptors.

The spiropyrrolizidine oximes 236 and 222 and a related spiropyrrolizidine alkaloid, nitropolyzonamine, block nicotinic receptor channels in rat pheochromocytoma PC12 cells and in human medulloblastoma TE671 cells. In PC12 cells with an alpha 3 beta 4(5)-nicotinic receptor, both the spiropyrrolizidine oxime 236 and nitropolyzonamine had IC50 values of about 1.5 microM, while spiropyrrolizidine oxime 222 had an IC50 value of 2.6 microM versus carbamylcholine-elicited sodium-22 influx. In TE671 cells with an alpha 1 beta 1 gamma delta nicotinic receptor, the spiropyrrolizidine oximes 236, 222, and nitropolyzonamine had IC50 values of 9.5, 14, and 67 microM, respectively. The inhibitions by the spiropyrrolizidine oxime 236 and nitropolyzonamine appeared to be noncompetitive in nature in both cell lines. In rat cerebral cortical membranes, binding of [3H]nicotine to alpha 4 beta 2 nicotinic receptors was not inhibited significantly by 10 microM concentrations of the spiropyrrolizidine oxime 236, or by nitropolyzonamine, as expected for a noncompetitive blocker. Both compounds at 10 microM had marginal effects on a variety of central receptors, but did inhibit binding of [3H]1,3-di(2-tolyl) guanidine to sigma receptors in mouse brain membranes with IC50 values of about 0.5 microM. The spiropyrrolizidine oxime 236 at 10 microM had no effect on batrachotoxin-elicited sodium influx in guinea pig cerebral cortical synaptoneurosomes or on ATP-elicited calcium influx in PC12 cells. Such spiropyrrolizidines represent a new structural class of blockers of nicotinic receptor channels with selectivity for ganglionic-type receptors.

Animals↗
PubMed1996

Interactions of the F1-ATPase subunits from Escherichia coli detected by the yeast two-hybrid system.

Subunit interactions among the F1-ATPase subunits were studied by the yeast two-hybrid system. Various pairwise combinations of genes encoding alpha, beta, gamma, delta and epsilon subunits of Escherichia coli H+-ATPase fused to the DNA-binding or activation domain of the yeast GAL4 gene were introduced into yeast and expression of a reporter gene encoding beta-galactosidase was detected. Combinations of the alpha and beta subunit genes, and of the epsilon and gamma subunit genes showed high levels of reporter gene expression, while those of alpha and delta, beta and delta, gamma and delta, and delta and epsilon demonstrated weak but significant reporter gene expression. However, combinations of alpha and gamma, beta and gamma, alpha and epsilon, and beta and epsilon did not induce reporter expression. None of the fused genes alone induced reporter gene expression. These results suggested that specific and strong interactions between the alpha and beta, gamma and epsilon, and weak interactions between the alpha and delta, beta and delta, and gamma and delta subunits occurred in yeast cells in the two-hybrid system. Effects of previously identified mutant beta subunits with Leu-40 to Pro. Glu-41 to Lys or Pro-332 to Gln substitutions which caused defects in molecular assembly of F1-ATPase were analyzed with regard to alpha-beta interactions. No interaction of the alpha and beta subunits was observed in this system using the beta subunit with mutation of Pro-332 to Gln. However, for the other two mutations, alpha-beta interactions were observed. This system may be useful for isolating mutants which have defects in interaction of F1-ATPase subunits.

Escherichia coli↗
PubMed1996

Reconstitution of the F1-ATPase activity from purified alpha, beta, gamma and delta or epsilon subunits with glutathione S-transferase fused at their amino termini.

Systems for overexpression and purification of active alpha, beta and gamma subunits of Escherichia coli H(+)-ATPase were established. The alpha and beta subunits recovered as soluble form were purified by hydroxyapatite column chromatography. Since the gamma subunit was overexpressed as the insoluble form, this subunit was purified by polyacrylamide gel-electrophoresis containing sodium dodecyl sulfate. By subsequent denaturation of this subunit with guanidine hydrochloride and renaturation, the active gamma subunit for reconstitution of the F1-ATPase activity with the purified alpha and beta subunit was obtained. The delta and epsilon subunits which were fused to the carboxy terminus of glutathione S-transferase (GST) were overproduced and purified by affinity chromatography. These fused proteins (delta-GST and epsilon-GST) were incubated with the purified alpha, beta and gamma subunits and applied to affinity chromatography. The alpha beta gamma delta-GST and alpha beta gamma epsilon-GST complex were eluted specifically by addition of glutathione and exhibited high and low ATPase activity, respectively, with a subunit stoichiometry similar to that in the native F1-ATPase, indicating that active complexes could be reconstituted with the fused proteins. These results suggested that the amino-terminal ends of the delta and epsilon subunits are not involved in formation of the active complex. The fused epsilon-GST bound the gamma subunit strongly, and the alpha subunit weakly. The delta-GST bound the gamma subunit significantly, and the alpha and beta subunits very weakly.

Base Sequence↗