Biomedical subjects

Mitsuru Murata

Publications and source records attributed to Mitsuru Murata.

At least 19 recordsLinked to original sources

PubMed2005

Assessment of tailor-made prevention of atherosclerosis with folic acid supplementation: randomized, double-blind, placebo-controlled trials in each MTHFR C677T genotype.

This study aimed at assessing the effect of folic acid supplementation quantitatively in each MTHFR C677T genotype and considered the efficiency of tailor-made prevention of atherosclerosis. Study design was genotype-stratified, randomized, double-blind, placebo-controlled trials. The setting was a Japanese company in the chemical industry. Subjects were 203 healthy men after exclusion of those who took folic acid or drugs known to effect folic acid metabolism. Intervention was folic acid 1 mg/day p.o. for 3 months. The primary endpoint was plasma total homocysteine level (tHcy). In all three genotypes, there were significant tHcy decreases. The greatest decrease was in the TT homozygote [6.61 (3.47-9.76) micromol/l] compared with other genotypes [CC: 2.59 (1.81-3.36), CT: 2.64 (2.16-3.13)], and there was a significant trend between the mutated allele number and the decrease. The tHcy were significantly lowered in all the genotypes, but the amount of the decrease differed significantly in each genotype, which was observed at both 1 and 3 months. Using these time-series data, the largest benefit obtained by the TT homozygote was appraised as 2.4 times compared with the CC homozygote. Taking into account the high allele frequency of this SNP, this quantitative assessment should be useful when considering tailor-made prevention of atherosclerosis with folic acid.

Alleles↗

PubMed2005

T280M and V249I polymorphisms of fractalkine receptor CX3CR1 and ischemic cerebrovascular disease.

The contribution to atherosclerosis of two CX3CR1 single nucleotide polymorphisms, V249I and T280M has been recently reported. The atherosclerosis of intracranial vessels is thought to be the major pathological mechanism of ischemic stroke. In this study, we investigated the risk of ischemic stroke associated with fractalkine receptor CX3CR1 polymorphisms. We investigated the T280M and V249I mutations in the CX3CR1 gene in 235 Japanese patients with ischemic cerebrovascular disease (CVD) and 306 age- and sex-matched healthy controls. Polymerase chain reaction and restriction fragment length polymorphism were used for genotyping. There was no significant difference in both polymorphisms between patients with ischemic CVD and controls (VV versus II+VI, p=0.83; TT versus MM+TM, p=0.66). The I and M allele frequencies were not significantly different between CVD patients and controls: odds ratio (OR)=0.89 (95% confidence interval (CI)=0.50-1.60, p=0.70) and OR=1.19 (95% CI=0.71-2.00, p=0.51), respectively. We found eight of nine possible combined genotypes, including a new haplotype V249-M280, in Japanese. Our results show that these CX3CR1 gene polymorphisms are not associated with an increased risk for ischemic CVD in the Japanese population.

CX3C Chemokine Receptor 1↗

PubMed2005

Factor XII Shizuoka, a novel mutation (Ala392Thr) identified and characterized in a patient with congenital coagulation factor XII deficiency.

We identified a novel mutation (Ala392Thr) in the factor XII (FXII) gene of a patient with congenital FXII deficiency, designated Factor XII Shizuoka. The proband was an asymptomatic 63-year-old Japanese male with an abnormal coagulation test, discovered by chance during preoperative testing. The FXII activity was under 3% and antigen level was under 10%. Sequence analysis of the proband's FXII gene revealed a homozygous nucleotide substitution G to A in exon 10, resulting in the amino acid substitution Ala392 to Thr in the catalytic domain. We constructed the mutant FXII cDNA in an expression plasmid vector and transfected it into Chinese hamster ovary (CHO) cells. The recombinant wild-type FXII antigen was detected in the culture medium by immunoprecipitation assay, but the mutant FXII (A392T) was not observed. Both the wild-type FXII and A392T cell lysates, however, contained equivalent levels of FXII antigen and FXII mRNA, as estimated by Western blotting and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. These findings suggest that the Ala392 to Thr substitution impairs intracellular protein processing and causes a cross-reacting material -negative FXII deficiency.

Amino Acid Substitution↗

PubMed2005

Genetic analysis of hereditary factor X deficiency in a French patient of Sri Lankan ancestry: in vitro expression study identified Gly366Ser substitution as the molecular basis of the dysfunctional factor X.

We investigated a new family with cross-reactive material-positive factor X (FX) deficiency. The proband was an 11-year-old French girl from Sri Lanka with a tendency towards severe bleeding. The FX antigen level was 67%, although the activity with extrinsic pathway was 1 U/dl. The complete nucleotide sequences of all exons and exon/intron junctions of the patient's genomic DNA revealed a homozygous G <-- A substitution in exon 8, which would result in replacement of Gly366 with Ser. The proband is the first reported case of homozygote for the FX Gly366Ser mutation. Heterozygosity for Gly366Ser substitution was previously reported in a Japanese patient (FX Nagoya 2). We studied the functional consequences by expressing mutant FX Gly366Ser protein in HEK293 cells. FX Gly366Ser was secreted into the culture media at levels similar to wild-type FX; however, mutant FX activities were only 0.04, 1.05, and 0.75% of wild-type FX upon activation by the extrinsic system, the intrinsic system, and Russell's viper venom, respectively. Moreover, the activity of FX Gly366Ser was undetectable when analyzed with chromogenic-activated FX and thrombin generation assays. These data suggest that the Gly366Ser substitution would cause a major defect in function of the FX molecule.

Amino Acid Substitution↗

PubMed2005

Platelet glycoprotein Ib alpha polymorphisms affect the interaction with von Willebrand factor under flow conditions.

Interaction of platelet glycoprotein (GP) Ibalpha with von Willebrand factor (VWF) is essential for thrombus formation, particularly under high shear conditions. Previous case-control studies indicated that two GPIb alpha polymorphisms, (145)Thr/Met and/or variable number (1-4) tandem repeats of 13 amino-acid sequences, are associated with arterial thrombosis. The (145)Met-allele and the 3R- or 4R-allele is associated with increased risk. However, there is little clear experimental data to support this association. To elucidate the functional effects of these polymorphisms, we prepared recombinant GPIb alpha fragments and tested them in vitro. The dissociation constants of ristocetin-induced (125)I-labelled VWF binding to two forms of soluble recombinant GPIb alpha [(1)His-(302)Ala, either (145)Thr (145T) or (145)Met (145M)] were not different. Four types of Chinese hamster ovary cells expressing full-length GPIb alpha beta/IX, 145T with one repeat (T1R), 145M with one repeat (M1R), 145T with four repeats (T4R), and 145M with four repeats (M4R), were prepared, and cell interactions with immobilized-VWF were examined under various shear conditions. The cell rolling velocity of M4R under a shear condition of 114/s was significantly slower than that of T1R. Intermediate values were obtained with M1R and T4R. The results suggest that M4R interacts more strongly with VWF under flow conditions.

Animals↗

PubMed2004

High throughput multiple combination extraction from large scale polymorphism data by exact tree method.

Single nucleotide polymorphisms (SNPs) are increasingly becoming important in clinical settings as useful genetic markers. For the evaluation of genetic risk factors of multifactorial diseases, it is not sufficient to focus on individual SNPs. It is preferable to evaluate combinations of multiple markers, because it allows us to examine the interactions between multiple factors. If all the combinations possible were evaluated round-robin, the number of calculations would rapidly explode as the number of markers analyzed increased. To overcome this limitation, we devised the exact tree method based on decision tree analysis and applied it to 14 SNP data from 68 Japanese stroke patients and 189 healthy controls. From the obtained tree models, we succeeded in extracting multiple statistically significant combinations that elevate the risk of stroke. From this result, we inferred that this method would work more efficiently in the whole genome study, which handles thousands of genetic markers. This exploratory data mining method will facilitate the extraction of combinations from large-scale genetic data and provide a good foothold for further verificatory research.

Adult↗

PubMed2004

Identification of novel mutations in ADAMTS13 in an adult patient with congenital thrombotic thrombocytopenic purpura.

Congenital thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) is associated with an inherited von Willebrand factor-cleaving protease (ADAMTS13 [a disintegrin and metalloprotease with thrombospondin type I domains 13]) deficiency. In this study, we identified novel mutations in the ADAMTS13 gene in a patient with TTP. The patient was a 51-year-old Japanese male who exhibited TTP symptoms at frequent intervals. The ADAMTS13 activity during acute episodes was less than 3% that of normal. The enzyme activities of the patient's father and mother were both 46%, and both parents were asymptomatic. Genetic analysis revealed that the patient was a compound heterozygote for 2 mutations. One mutation was a missense mutation in the metalloprotease domain (A250V, exon 7), and the other was a guanine to adenine substitution at the 5' end of intron 3 (intron 3 G-->A). In vitro expression studies revealed that the A250V mutation markedly reduced ADAMTS13 activity and the intron 3 G-->A mutation caused abnormal mRNA synthesis.

ADAM Proteins↗

PubMed2004

Detection of von Willebrand factor-cleaving protease (ADAMTS-13) in human platelets.

The hemostatic activity of von Willebrand factor (vWF) is strongly dependent on its multimeric structure, with the highest activity in 'unusually large' multimers secreted from endothelial cells. The multimeric structure is regulated by a plasma protease, vWF-cleaving protease (vWF-CP, or ADAMTS-13). ADAMTS-13 mRNA is variably expressed in liver and other tissues. Because 15-25% of circulating vWF is stored in platelets, the presence and function of ADAMTS-13 in platelets are important issues. Here we report ADAMTS-13 expression in human platelets. Western blot analysis and flow cytometric analysis on permeabilized platelets revealed the presence of ADAMTS-13 protein. Real-time PCR demonstrated that ADAMTS-13 mRNA is present in platelets of six healthy volunteers, with little quantitative difference. The presence of ADAMTS-13 in platelets may imply the functional role of this enzyme in the local regulation of platelet function at the site of vascular injury or thrombus formation, and provide a useful tool for the analysis of structure and function of this enzyme.

ADAM Proteins↗

PubMed2004

Genetic analyses and expression studies identified a novel mutation (W486C) as a molecular basis of congenital coagulation factor XII deficiency.

We analyzed the factor XII (FXII) gene of a patient with congenital FXII deficiency and identified a novel amino acid substitution (W486C) in the catalytic domain. The proband was an asymptomatic 49-year-old Japanese female with abnormal coagulation test, discovered by chance. The FXII activity and antigen level were both under 10%, suggesting a cross-reacting material-negative FXII deficiency. Sequence analysis of the proband's FXII gene revealed a homozygous nucleotide substitution G --> C in exon 12, resulting in the amino acid substitution W486C in the catalytic domain. We constructed the mutant FXII cDNA in an expression plasmid vector and transfected it into Chinese hamster ovary cells. The recombinant wild-type FXII antigen was detected in the culture medium by immunoprecipitation assay, but the mutant FXII (W486C) was not observed. On the other hand, both the wild-type FXII and W486C cell lysates contained FXII antigen and FXII mRNA, as estimated by western blotting and quantitative reverse transcriptase-polymerase chain reaction. These findings suggest that the W486C substitution of FXII impairs intracellular processing of the protein and/or transport system.

Amino Acid Substitution↗

PubMed2004

Relation between development of nephropathy and the p22phox C242T and receptor for advanced glycation end product G1704T gene polymorphisms in type 2 diabetic patients.

OBJECTIVE: The development of diabetic nephropathy is considered to be associated with oxidative stress. NADPH oxidase and the receptor for advanced glycation end products (RAGE) have attracted attention as mechanisms of generating oxidative stress. We studied the relation between the genotypes of the NADPH p22phox C242T and RAGE G1704T polymorphisms and the development of diabetic nephropathy in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Using a retrospective review of clinical data, we allocated 181 Japanese type 2 diabetic patients to one of two groups: patients without diabetic nephropathy (group N; n = 108) and patients developing diabetic nephropathy (group D; n = 73) for 10 years or more. The p22phox C242T and RAGE G1704T polymorphisms were examined by Taqman PCR methods. RESULTS: The frequency of the p22phox CC genotype was significantly higher in group D than in group N (90 vs. 79%; P = 0.0427). The frequency of the RAGE GT + TT genotype was significantly higher in group D than in group N (26 vs. 13%; P = 0.0313). The frequency of the combination of p22phox CC and RAGE GT + TT genotypes was significantly higher in group D than in group N (22 vs. 8%; P = 0.0057). In multiple logistic regression analysis, systolic blood pressure, HbA(1c), triglycerides, and the combination of polymorphisms were shown to be independent variables. CONCLUSIONS: These results suggest that assessment of the combination of NADPH p22phox C242T and RAGE G1704T polymorphisms may be useful in identifying the risk for developing diabetic nephropathy in type 2 diabetic patients.

Adult↗

PubMed2004

[Genetic risk factors for ischemic cerebrovascular disease--analysis on fifteen candidate prothrombotic gene polymorphisms in the Japanese population].

Accumulating evidence suggests that several polymorphisms in factors regulating blood coagulation, platelet function, and lipid metabolism are relevant for susceptibility to ischemic cerebrovascular diseases (CVD). The present study analyzed 15 genetic polymorphisms possibly associated with atherosclerosis and thrombosis in a case-control study involving a total of 200 genetically unrelated Japanese patients with ischemic CVD (mean age 58.3 +/- 7.6 y) and 281 age- and gender-matched control subjects (59.0 +/- 4.1 y). Control subjects were randomly selected from unrelated donors with no history of documented CVD or any type of cardiovascular disease with normal resting electrocardiograms. Among the factors genotyped, two factors, platelet glycoprotein (GP) Ib alpha (Thr145Met) and NADPH oxidase p22phox (His72Tyr), were significantly associated with CVD after adjustment for acquired risk factors including hypertension, diabetes mellitus, hyperlipidemia, and smoking. For those with age < 60 y, 10.6% of the CVD patients and 2.9% of the control subjects had both of the two risk genotypes (GPIb alpha 145Met and p22phox 72Tyr, p < 0.05). The mean onset-age of CVD was 58.6 +/- 7.7 y for those having no or only one risk genotype, while 53.3 +/- 5.5 y for those having both of the risk genotypes (p < 0.05). Thus, GPIb alpha 145Met and p22phox 72 Tyr are the genetic factors associated with the risk of ischemic CVD in the Japanese. Carrying both of the two mutations might be associated with developing CVD at a younger age.

Aged↗

PubMed2003

Correlation between serum resistin level and adiposity in obese individuals.

OBJECTIVE: Resistin is associated with insulin resistance in mice and may play a similar role in humans. The aim of our study was to examine the relationship of serum resistin level to body composition, insulin resistance, and related obesity phenotypes in humans. RESEARCH METHODS AND PROCEDURES: Sixty-four young (age 32 +/- 10 years), obese (BMI 32.9 +/- 5.6), nondiabetic subjects taking no medication, and 15 lean (BMI 21.1 +/- 1.3) volunteers were studied cross-sectionally. Thirty-five of the subjects were also reevaluated after 1.5 years on a weight reduction program entailing dieting and exercise; changes of serum resistin were compared with changes of BMI, body composition, fat distribution, and several indices of insulin sensitivity derived from plasma glucose and serum insulin levels measured during 75-g oral glucose tolerance test. RESULTS: In a cross-sectional analysis, serum resistin was significantly higher in obese subjects than in lean volunteers (24.58 +/- 12.93 ng/mL; n = 64 vs. 12.83 +/- 8.30 ng/mL; n = 15; p < 0.01), and there was a correlation between resistin level and BMI, when the two groups were combined (rho = 0.35, p < 0.01). Although cross-sectional analysis in obese subjects revealed no correlation between serum resistin and parameters related to adiposity or insulin resistance, longitudinal analysis revealed change in serum resistin to be positively correlated with changes in BMI, body fat, fat mass, visceral fat area, and mean glucose and insulin (rho = 0.39, 0.40, 0.44, 0.50, 0.40, and 0.50; p = 0.02, 0.03, 0.02, <0.01, 0.02, and <0.01, respectively). DISCUSSION: Resistin appears to be related to human adiposity and to be a possible candidate factor in human insulin resistance.

Adipose Tissue↗

PubMed2003

Bernard-soulier syndrome with a homozygous 13 base pair deletion in the signal peptide-coding region of the platelet glycoprotein Ib(beta) gene.

We report a family with Bernard-Soulier syndrome with a homozygous mutation within the GPIb(beta) gene. The proband was a 24-year-old Japanese male who has suffered from life-long bleeding tendency. The patient's sister also had severe bleeding episodes. The proband and the affected sister had no apparent complications including organic or skeletal anomaly, or mental disturbance. They had thrombocytopenia [(35-40) x 10(9)/l] with giant platelets. In addition to platelet size, electron microscopic analysis revealed abnormalities in the internal structures of platelets. Ristocetin-induced platelet aggregation was defective. Flow cytometric analysis and western blot analysis showed that glycoprotein IX was nearly absent in platelets, whereas GPIb(alpha) and GPV were detectable. Genetic studies revealed a 13 base pair deletion in the signal peptide-coding sequence of GPIb(beta). The deletion would cause a frame-shift, resulting in the appearance of a stop codon following an indifferent polypeptide sequence. Analysis of platelet RNA showed that the mutant GPIb(beta) gene was transcribed. The propositus and his affected sister were homozygous for the deletion, whereas their unaffected father and mother were heterozygotes. The molecular defects of this family would help understand the relevance of GPIb(beta) for complex formation of the glycoprotein Ib/IX/V receptor.

Adult↗

PubMed2003

The ratio of serum paraoxonase/arylesterase activity using an improved assay for arylesterase activity to discriminate PON1(R192) from PON1(Q192).

Human serum paraoxonase (PON1) exists in 2 major polymorphic forms: Q (glutamine) or R (arginine) at codon 192. The PON1(192) activity polymorphism is substrate dependent. The PON1(Q192) isoform has a higher rate of in vitro hydrolysis of diazoxon, sarin, and soman, whereas the PON1(R192) isoform has higher activity for the hydrolysis of paraoxon and chlorpyrifos oxon. Both isoforms hydrolyze phenyl acetate at approximately the same rate. The present study described and evaluated a kinetic method of arylesterase activity determination with a modified fixed incubation method that used the oxidative coupling of phenol with 4-aminoantipyrine of phenyl acetate as the substrate. Our improved method shows that arylesterase activity is lower with the PON1(R192) isoform than with the PON1(Q192) isoform. The average activities of serum of individuals of a specific PON1(Q192) genotype showed higher arylesterase and lower paraoxonase activity than the PON1(R192) genotype. The ratio of paraoxonase/arylesterase activity showed a clear separation of all three PON1(192) genotypes with no overlap between the groups (QQ: < 5.0, QR: 5.0-11.0, RR: > 11.0). PCR has suggested that the PON1(192) phenotypes correspond to the PON1(192) genotypes. Therefore, when conducting epidemiological or mechanistic studies that examine the role of PON1 in organophosphorus or lipid metabolism, this ratio is more useful and informative than a PCR-based genotype alone.

Adult↗

PubMed2003

[Wilson's disease associated with olfactory paranoid syndrome and idiopathic thrombocytopenic purpura].

In this study we report an individual of Wilson's disease associated with olfactory paranoid syndrome and idiopathic thrombocytopenic purpura. The initial symptom of this female patient was olfactory paranoia at age 17. Although that psychiatric symptom was well controlled under pharmacological treatment for two years, she developed olfactory paranoia as well as sialorrhea, dysarthria and finger tremor at age 20. A year later rigidity was also present in the extremities. At age 23, idiopathic thrombocytopenic purpura was found based on hematological examinations. Because her extrapyramidal symptoms were progressive, she was referred to our department to evaluate her neurologic condition. She was diagnosed as having Wilson's disease based on (1) the presence of Kayser-Fleischer rings, (2) extrapyramidal signs, and (3) a decreased level of serum copper and ceruloplasmin. T2 and FLAIR images of brain MRI showed hyperintense lesions in the putamen, thalamus and pontine tegmentum. Diffusion-weighted images also showed hyperintense lesions in the thalamus and pontine tegmentum. The biopsy specimen of the liver revealed chronic hepatitis with copper accumulation. Since D-penicillamine treatment was initiated, she has shown no olfactory paranoia and exacerbation of ITP. Her gait disturbance has also improved. Olfactory paranoia and ITP are rare clinical complications of Wilson's disease. Further analysis may warrant consideration of the pathophysiological mechanism of the psychiatric, hematological and neuroradiological condition seen in Wilson's disease.

Adult↗

PubMed2002

Reconstitution of adhesive properties of human platelets in liposomes carrying both recombinant glycoproteins Ia/IIa and Ib alpha under flow conditions: specific synergy of receptor-ligand interactions.

Liposomes carrying both recombinant glycoprotein Ia/IIa (rGPIa/IIa) and Ib alpha (rGPIb alpha) (rGPIa/IIa-Ib alpha-liposomes) instantaneously and irreversibly adhered to the collagen surface in the presence of soluble von Willebrand factor (VWF) at high shear rates, in marked contrast with translocation of liposomes carrying rGPIb alpha alone on the VWF surface. In the absence of soluble VWF, the adhesion of rGPIa/IIa-Ib alpha-liposomes to the collagen surface decreased with increasing shear rates, similar to liposomes carrying rGPIa/IIa alone. While adhesion of liposomes with exofacial rGPIa/IIa and rGPIb alpha densities of 2.17 x 10(3) and 1.00 x 10(4) molecules per particle, respectively, was efficient at high shear rates, reduction in rGPIb alpha density to 5.27 x 10(3) molecules per particle resulted in decreased adhesion even in the presence of soluble VWF. A 50% reduction in the exofacial rGPIa/IIa density resulted in a marked decrease in the adhesive ability of the liposomes at all shear rates tested. The inhibitory effect of antibody against GPIb alpha (GUR83-35) on liposome adhesion was greater at higher shear rates. Further, the anti-GPIa antibody (Gi9) inhibited liposome adhesion more than GUR83-35 at all shear rates tested. These results suggest that the rGPIa/IIa-collagen interaction dominates the adhesion of rGPIa/IIa-Ib alpha-liposomes to the collagen surface at low shear rates, while the rGPIa/IIa-collagen and rGPIb alpha-VWF interaction complements each other, and they synergistically provide the needed functional integration required for liposome adhesion at high shear rates. This study thus has confirmed for the first time the proposed mechanisms of platelet adhesion to the collagen surface under flow conditions using the liposome system.

Antigens, CD↗

PubMed2002

The frequent 5,10-methylenetetrahydrofolate reductase C677T polymorphism is associated with a common haplotype in whites, Japanese, and Africans.

The common 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism causes decreased activity of this enzyme and can be associated with mild-to-moderate hyperhomocysteinemia in homozygotes, particularly when there is folic acid deficiency, as well as with vascular dementia, arterial thrombosis, venous thrombosis, neural-tube defects, and fetal loss. When folic acid intake is sufficient, homozygotes for MTHFR 677T appear to be protected against colon cancer and acute lymphatic leukemia, and fetuses bearing this genotype have an augmented survival. The distribution of MTHFR 677T is worldwide, but its frequency in different populations varies extensively. In the present study, we addressed the question of whether the MTHFR 677T alteration has an ancestral origin or has occurred repeatedly. We analyzed the frequency distribution of the previously described polymorphism A1298C in exon 7 and of three intronic dimorphisms, in white Israelis (Jews and Arabs), Japanese, and Ghanaian Africans. The 677T allele was, remarkably, associated with one haplotype, G-T-A-C, in white and Japanese homozygotes. Among the Africans, analysis of maximum likelihood also disclosed an association with the G-T-A-C haplotype, although none of the 174 subjects examined was homozygous for MTHFR 677T. These results suggest that the MTHFR 677T alteration occurred on a founder haplotype that may have had a selective advantage.

Arabs↗

PubMed2002

Shear-induced platelet aggregation increases in patients with proximal and severe coronary artery stenosis.

BACKGROUND: Shear stress generated in stenosed arteries promotes platelet thrombi formation at the stenosed sites by accelerating the binding of von Willebrand factor (vWF) to platelets. Shear-induced platelet aggregation (SIPA) has been studied in acute coronary syndromes, but not in chronic coronary disease. HYPOTHESIS: We investigated the effect of both the site and severity of coronary stenosis on SIPA in patients with chronic coronary artery disease. METHODS: Shear-induced platelet aggregation was measured using platelet-rich plasma in 49 patients (41 men and 8 women; mean age 61+/-10 years) with coronary artery disease to evaluate the association between the extent of SIPA and coronary angiographic findings. Stenoses > 75% were considered severe. In all, 62 healthy individuals (54 men and 18 women; mean age 45+/-7 years) served as controls. The correlation between SIPA and the site and severity of the coronary lesion, and parameters of coagulation and fibrinolysis were evaluated. RESULTS: Shear-induced platelet aggregation was increased in the stenosis group (69.0+/-10.6%) compared with the controls (57.7+/-10.3%, p < 0.0001). Patients with severe stenosis in the proximal segments had significantly increased SIPA (p< 0.0001) and vWF larger multimer concentration (p<0.0001) compared with the control group. A significant correlation existed between SIPA and the vWF larger multimer concentration in all subjects studied (r = 0.422, p < 0.0001). CONCLUSIONS: Shear-induced platelet aggregation is increased in patients with severe stenosis of the proximal coronary arteries and correlates with plasma concentrations of vWF larger multimers, suggesting that severe stenosis in the proximal segments is not only associated with an increased risk of significant myocardial ischemia, but may also generate high shear stress in the stenosed artery and increase plasma vWF larger multimers, thereby promoting the formation of platelet thrombi.

Adult↗