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Biomedical subjects

Y L Ko

Publications and source records attributed to Y L Ko.

At least 19 recordsLinked to original sources
PubMed2001

Importance of hyperhomocysteinemia as a risk factor for venous thromboembolism in a Taiwanese population. A case-control study.

OBJECTIVE: To determine the current status of hyperhomocysteinemia, which is a known risk for venous thrombosis (DVT), in Taiwan. SUBJECTS: 101 unselected patients with a minimum of one episode of deep leg DVT, either initial inpatients or current compliant outpatients in a teaching hospital. METHODS: Various thrombophilic risks, gene polymorphism and clinical predisposition were evaluated. RESULTS AND CONCLUSIONS: Patients presented higher fast total plasma homocysteine (hcy) levels than age- and sex-matched controls did (14.1 vs. 9.94 microM). Based on the 95th percentile of control values, hyperhomocysteinemia had a four- to nine-fold risk for DVT, irrespective of clinical predisposition, as well as other thrombophilic risks surveyed. Polymorphism of a metabolizing enzyme, methylenetetrahydrofolate reductase (MTHFR), was not associated with DVT, although homozygous thermolabile mutation tended to have higher plasma hcy levels. Factor V Leiden was absent in analysis of 80 patients. In complete evaluation (hcy, antithrombin (AT), protein S (PS), protein C (PC), lupus anticoagulant (LA), anticardiolipin antibody) of a subset of 83 patients hyperhomocysteinemia was the most prevalent risk (33.7%), with PC or PS deficiencies following (22.9%). Thus, hyperhomocysteinemia is a prominent risk for DVT in Taiwan.

Adult↗
PubMed2001

A noninvasive estimation of hypernasality using a linear predictive model.

The pronunciation of a speaker with a defective soft palate is marked by hypernasality and an operation may be necessary to repair the defective soft palate to reduce this hypernasality. An assessment of hypernasality is necessary to quantify the effect of the surgery. The current clinical methods for assessing hypernasality are uncomfortable or require expensive equipment. In this paper, a new quantitative method is proposed to estimate hypernasality. This method requires only a microphone and a personal computer equipped with a sound card. Zeros in the frequency response of the vocal tract system are one of the major characteristics of hypernasality. The proposed method made use of the fact that a linear predictive model with a typical order for the human vocal tract system is not accurate when the vocal tract system has zeros in its frequency response. Hypernasality was estimated by comparing the distance between the sequences of linear predictive cepstrum of low- and high-order linear predictive models. The proposed method provides a better correlation (0.58) with nasalance measured by a nasometer than Teager method (0.44) for all the data. Furthermore, the proposed method showed higher correlation of 0.84 than 0.71 of the Teager method for data with a nasalance higher than 35%. Since the proposed method needs only digitized speech data, it is much less invasive and provides an easy and cost-effective evaluation of hypernasality.

Biomedical Engineering↗
PubMed2001

The C677T mutation of the methylenetetrahydrofolate reductase gene is not associated with the risk of coronary artery disease or venous thrombosis among Chinese in Taiwan.

OBJECTIVES: We sought to investigate the association between the methylenetetrahydrofolate reductase (MTHFR) gene C677T mutation and the risk of coronary artery disease (CAD), myocardial infarction (MI) and venous thrombosis (VT) in a Chinese population in Taiwan. METHODS: The subjects included 218 CAD patients, 107 VT patients, and their age- and sex-matched controls. DNA was extracted from the blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI and gel electrophoresis. RESULTS: The distribution of MTHFR genotypes was similar in the CAD cases and controls; the genotype TT was present in 6.0% of CAD patients, as compared to 6.9% of CAD control subjects (p = 0.165; odds ratio = 0. 86; 95% confidence interval = 0.40-1.85). The frequency of the T allele was also similar in CAD cases and controls (25.5% vs. 24.8%; p = 0.788). There was no significant association between TT homozygosity and the risk of MI. The genotype distributions and the frequency of the T allele were also similar in VT cases and controls. CONCLUSIONS: Our data suggest that there is no association between the C677T mutation of the human MTHFR gene and the risk of CAD or VT among Chinese in Taiwan.

Alleles↗
PubMed2001

Unusual electrocardiographic manifestations in acute isolated right ventricular infarction.

Electrocardiographic (ECG) manifestation of ST-segment elevation in the precordial leads during acute myocardial infarction is usually due to anterior myocardial infarction secondary to occlusion of the left coronary artery. Herein, we reported a rare case of isolated right ventricular infarction (RVI) in which the ECG mimicked that of acute anterior left ventricular infarction (LVI). A 64-year-old man had acute isolated RVI documented by positive cardiac enzymes and echocardiographic and angiographic findings. He developed hypotension. His ECG showed ST-segment elevation in the precordial leads V1 to V3 simulating that of acute anterior wall infarction. Coronary angiogram revealed total occlusion of the proximal right coronary artery with well-established collaterals from the left coronary artery to the posterior descending artery. This case report reminds us that the presence of diffuse ST-segment elevation in the precordial leads could be due to acute isolated RVI rather than acute anterior LVI. The differentiation of these two entities is important, as their therapies are quite different.

Electrocardiography↗
PubMed2001

Lack of association between the Glu298Asp variant of the endothelial nitric oxide synthase gene and the risk of coronary artery disease among Taiwanese.

BACKGROUND AND PURPOSE: Endothelial nitric oxide synthase (eNOS) plays a key role in atherosclerosis, because its product, nitric oxide, possesses antiatherogenic properties. Recent reports of molecular genetic analysis have suggested that genetic polymorphisms of the eNOS gene may be associated with coronary artery disease (CAD) or myocardial infarction (MI). However, some studies have reported discrepant results. The aims of this study were to assess whether any association exists between the Glu298Asp variant of the eNOS gene and the risk of CAD and/or MI among Taiwanese. METHODS: The subjects included 218 CAD patients and the same number of age- and sex-matched control subjects from Taiwan. Subjects' DNA was extracted from their blood and genotypes were determined by polymerase chain reaction and restriction mapping using the restriction enzyme MboI. The alleleic and genotypic frequencies were analyzed. RESULTS: The frequencies of the eNOS genotypes were similar for CAD patients (GG:GT:TT = 81.7%:17.4%:0.9%) and controls (81.2%:17.4%:1.4%; p = 0.904). No evidence of difference was found in the frequency of the T allele between CAD patients (9.6%) and controls (10.1%; p = 0.822), or between MI patients (7.5%) and controls (p = 0.322). Subjects with the GT or TT genotype did not demonstrate an increased risk of CAD compared with those with a GG genotype (p = 0.89; OR = 0.98; 95% confidence interval, CI, 0.76-1.27) in multivariate logistic regression, or when different subgroups of age, sex, or risk factors were analyzed. CONCLUSIONS: In the present case-control study, we found no evidence of an association between the Glu298Asp variant of the eNOS gene and CAD/MI among Taiwanese.

Coronary Disease↗
PubMed2001

Linkage and mutation analysis in two Taiwanese families with long QT syndrome.

Long QT syndrome (LQT) is a cardiovascular disorder causing syncope and sudden death from arrhythmias. Mutations in KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A genes encoding cardiac potassium and sodium ion channels cause LQT. Two Taiwanese LQT families were screened for mutations in these ion channel genes. In family H87, the diagnosis was made in the 25-year-old female proband and six family members based on recurrent syncope and/or a prolonged QT interval. Genotyping revealed a novel nonsense mutation, R744X (C to T transition in codon 744), in the KCNH2 potassium channel gene, resulting in truncation of the putative cyclic nucleotide-binding domain and C-terminal region of the HERG K(+)-channel in all affected family members. The mutation was confirmed by DdeI endonuclease digestion of the DNA from each family member. The 26-year-old female proband in family L89 developed repeated syncope with QTc of 0.61 seconds. After linkage and mutation analysis, the syndrome in this family was associated with a novel KCNQ1 missense mutation, T309I, causing the substitution of a threonine residue at position 309, in the pore region of the KvLQT1 K(+)-channel, with an isoleucine. By Tsp45I restriction analysis, the mutation was noted in the proband and the proband's asymptomatic brother, but was not detected in 100 unrelated normal individuals. Identification of a mutation has clinical implications for presymptomatic diagnosis and therapy.

Adult↗
PubMed2000

Sinoatrial nodal artery aneurysm with right ventricular outflow tract compression: report of a case.

We described a 16-year-old boy with sinoatrial nodal (SAN) artery aneurysm that drained into right atrium and compressed right ventricular outflow tract. The patient was clinically asymptomatic. Hemodynamic study revealed a 15 mm Hg peak systolic pressure gradient at right ventricular outflow tract. The fistula was successfully excised without sequalae. Cathet. Cardiovasc. Intervent. 51:328-331, 2000.

Adolescent↗
PubMed1999

Gender differences in the presentation of adult obstructive hypertrophic cardiomyopathy with resting gradient: a study of 122 patients.

The present study investigated gender differences among adult patients with obstructive hypertrophic cardiomyopathy (OHCM) and resting gradient. Using outflow gradients >10 mmHg and the presence of asymmetrical septal hypertrophy of the left ventricle as inclusion criteria, 122 patients were identified among patients referred for echocardiographic examinations between May 1990 and October 1996. Clinical, echocardiographical and follow-up data were compared between male and female patients. The female patients were significantly older than male patients (mean age +/-SD 66.7+/-10.5 vs 54.8+/-12.5 years). The female patients had a smaller interventricular septal wall thickness, less frequent systolic anterior movement of the mitral valve, more frequent association with hypertension, and less frequent association with ischemic heart disease (IHD) and giant T wave inversion. In this study population, adult female patients presented with OHCM 12 years later than males. Whether this represents female patients' reluctance to seek medical attention early, a different disease process that affects predominantly elderly females, or a gender-specific end organ response to aging, hypertension, IHD and other processes, or the protective effects of estrogen remains to be determined.

Adolescent↗
PubMed1999

Obstructive hypertrophic cardiomyopathy in Taiwanese adults.

The purpose of this study was to analyze the clinical profiles, echocardiographic findings, and mortality among adult Taiwanese patients with obstructive hypertrophic cardiomyopathy (HCM) at Chang Gung Memorial Hospital, a university-affiliated tertiary referral center in suburban Taipei. We reviewed the medical records of all adult (> 15 years of age) patients referred to our laboratory for echocardiographic examinations of cardiac diseases from May 1990 through December 1996. The diagnosis of obstructive HCM required an outflow gradient of above 10 mm Hg and the presence of asymmetric septal hypertrophy of the left ventricle. Follow-up information on was obtained from hospital records, questionnaires, interviews, or the National Death Certificate Registry. Of the 6.798 adults who underwent echocardiographic examinations during the study period 122 (1.79%) had obstructive HCM. The mean +/- standard deviation age of the patients was 62.2 +/- 12.6 years, and females predominated (n = 76, 62.3%). During the mean follow-up period of 3.2 years, the annual all-cause mortality rate was 4.7%. Most deaths were due to concurrent medical conditions. The annual cardiac mortality rate was 0.99%. Logistic regression analysis identified medication with calcium channel blockers as the only negative predictor (relative risk = 0.26, 95% confidence interval = 0.07-0.96) of all-cause mortality, and left atrial size as the only positive predictor (relative risk = 1.18, 95% confidence interval = 1.02-1.37) of cardiac mortality. Cox regression analysis confirmed the former association, but not the latter. Thus, in our institution, obstructive HCM had a low prevalence among adult patients referred for echocardiographic examination. These patients were elderly and often had other associated medical conditions. The high all-cause mortality rate was largely due to non-cardiac causes. These findings suggest that obstructive HCM tends to have a benign clinical course. Large atrial size could be an independent predictor of cardiac mortality, but this possibility requires further confirmation.

Aged↗
PubMed1998

Gender differences in baseline variables, therapies and outcomes in Chinese patients with acute myocardial infarction.

We prospectively studied the gender differences of baseline variables, therapies, and outcomes among a cohort of 369 Chinese patients with acute myocardial infarction from 1990 to 1995. There were 277 male and 92 female patients. The male gender had a younger mean (+/-SD) age (61.5+/-10.7 vs. 67.1+/-11.7 years, P<0.0001). Hypercholesterolemia (201.2+/-44.2 vs. 187.5+/-43.7 mg/dl, P=0.0111) and obesity (25.0 vs. 15.9%, P=0.0494) were more prominent in the female. Smoking was more prevalent in the male (78.3 vs. 18.5%, P<0.0001). The male group also had more frequent use of thrombolytic agents (19.1 vs. 9.8%, P=0.0377), beta-blockers (61.7 vs. 47.8%, P=0.0191) and heparin (25.3 vs. 12.0%, P=0.0075); but less use of angiotensin-converting enzyme inhibitors (6.9 vs. 15.2%, P=0.0149). The condition on admission was worse in the female group (Killip classification (1.5+/-0.9 vs. 1.9+/-1.0, P=0.0022), myocardial failure (8.7 vs. 2.9%, P=0.0178) and cardiomegaly (65.2 vs. 53.1%, P=0.0419). During a follow-up duration of 26.4+/-24.1 and 22.9+/-23.9 months respectively, the mortality rate was lower in the male (19.5 vs. 30.4%, P=0.0288). However after adjustment for the effect of age, the differences in Killip classification, myocardial failure, cardiomegaly and mortality became insignificant.

Aged↗
PubMed1998

Catheterization-documented coronary artery disease in young Chinese adults.

We conducted a retrospective study among 31 young (age<40 years) Chinese patients with catheterization-documented coronary artery disease. Male gender and smoking were the most important risk factors. Most of them had a single or two-vessel coronary artery disease. Standard treatment strategies could be applied. The prognosis appeared to be excellent.

Adult↗
PubMed1998

Stereochemistry and biological activities of constituents from Cynanchum taiwanianum.

The stereochemistry of new acetophenones, cynandione B-D (2-4), isolated from Cynanchum taiwanianum, elucidated by computer modelling calculation and NOESY spectrum. It establishes the absolute configurations of cynandiones B-D (2-4) as 7R; 7"S, 7S; 7"S and 7R; 7"R, respectively. Cynandione B (2) strongly inhibited the release of beta-glucuronidase and lysozyme in formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated rat neutrophils in a concentration-dependent manner with IC50 values of 1.5 +/- 0.2 and 1.6 +/- 0.2 microM, respectively. 2,5-Dihydroxyacetophenone (6) strongly inhibited the aggregation of washed rabbit platelets induced by arachidonic acid in a concentration-dependent manner with an IC50 value of about 4.8 microM. In human citrated platelet-rich plasma, 2,5-dihydroxyacetophenone (6) inhibited the secondary phase, but not the primary phase, of aggregation induced by adrenaline and ADP. These results suggest that the antiplatelet effect of 2,5-dihydroxyacetophenone (6) is due to inhibition of the formation of thromboxane A2.

Acetophenones↗
PubMed1998

The Gln-Arg 191 polymorphism of the human paraoxonase gene is not associated with the risk of coronary artery disease among Chinese in Taiwan.

Paraoxonase (PON1) is a high density lipoprotein-associated enzyme capable of hydrolyzing lipid peroxides, and thus, might protect lipoproteins from oxidation. A common polymorphism due to an amino acid substitution (Gln-Arg) at codon 191 is considered to be a major determinant of variation in serum PON1 activity. Recent studies have suggested that the PON1-191 polymorphism is an independent risk factor for coronary atherosclerosis in patients with or without diabetes mellitus. The association of PON1-191 polymorphism genotypes and coronary artery disease (CAD) among Chinese subjects in Taiwan was examined. The genotype of 218 angiographically documented CAD patients and the same number of age- and sex-matched control subjects was determined. Genotypes AA, AB and BB were present in 25 (11%), 102 (47%) and 91 (42%) of control subjects, respectively, and in 30 (14%), 96 (44%) and 92 (42%) of CAD patients, respectively (chi2 = 0.57, P = 0.75 between groups). The frequency of the A allele was 0.36 for the control group and 0.35 for CAD patients (P = 0.94). No significant differences in the PON1-191 genotype frequencies could be found between groups when multivariate logistic regression analysis was performed, or different subgroups of age, sex or risk factors were analyzed. Among control subjects, there was also no significant difference between genotypes of the PON1-191 polymorphism and various clinical and lipid variables. In conclusion, our data suggest that there is no association between the Gln-Arg 191 polymorphism of the human PON1 gene and CAD among Chinese subjects in Taiwan.

Alleles↗
PubMed1998

Genetic heterogeneity for familial hypertrophic cardiomyopathy in Chinese: analysis of six Chinese kindreds.

OBJECTIVE: Familial hypertrophic cardiomyopathy (FHCM) is a primary myocardial disease characterized by unexplained ventricular hypertrophy. The application of the techniques of reverse genetics has identified at least five chromosomal loci as the major causes for FHCM in diverse ethnic populations, suggesting substantial genetic heterogeneity for FHCM. Recently, the defective gene loci of two Chinese families with FHCM have been mapped to chromosome 11 and 14q1, respectively. For further understanding of the molecular basis of FHCM in Chinese, we analyzed the linkage between four other Chinese kindreds and DNA markers from chromosome 14q1. METHODS: Six unrelated Chinese families with FHCM, including two previously reported, were studied. Totally 90 family members were included for analysis. DNA from 80 individuals was extracted and polymerase chain reactions were performed using the primers designed according to the sequences derived from the alpha and beta myosin heavy chain gene. Totally four polymorphisms were studied, including three polymorphic microsatellite sequences and one single strand conformation polymorphism. Genetic linkage analysis were performed using the Linkage program. RESULTS: In the six studied families, 39 of the 90 family members were found to be affected diagnosed either by echocardiography or by clinical evaluation. The pattern of inheritance in all six studied families was most consistent with an autosomal dominant trait with a high degree of penetrance. Genetic linkage analysis using polymorphisms on the alpha and beta MHC genes showed a combined maximal lod score of 6.2 for trinucleotide repeat polymorphism AMHC-I 15 at theta = 0.00 for three studied families without recombination. Exclusion of linkage to the chromosome 14q1 location was noted in two of three other families with the maximal lod score of -2 or less. CONCLUSIONS: These results provide further evidence that FHCM in Chinese is genetically heterogeneous. Chromosome 14q1 locus, probably the beta myosin heavy chain gene, is important as the molecular basis for FHCM in Chinese.

Adolescent↗
PubMed1997

Angiotensinogen and angiotensin-I converting enzyme gene polymorphisms and the risk of coronary artery disease in Chinese.

The homozygous deletion allele (DD) of the angiotensin-I converting enzyme (ACE) gene and the T235 homozygote of the angiotensinogen (AGT) gene have been reported to be correlated with an increased prevalence of coronary artery disease (CAD) and myocardial infarction (MI). The importance of the DD genotype and T235 homozygote as genetic risk factors for CAD in Chinese remains uncertain. This study included 426 patients who underwent coronary angiography and 180 healthy subjects without clinical evidence of CAD. Coronary angiography identified 268 patients with CAD (CAD group) and 158 patients without CAD. The healthy subjects and patients without angiographic evidence of CAD constituted the control group. Three polymorphisms were studied: an insertion/deletion (I/D) polymorphism of the ACE gene and the T174 M and M235T polymorphisms of the AGT gene. No association was found between any of the three studied polymorphisms and the risk of CAD or MI in Chinese using univariate or multivariate analysis. In multivariate analysis, the relative risks were 1.20 (95% confidence interval = 0.91-1.61, P = 0.20) for the DD genotype, 1.05 (95% CI = 0.82-1.35, P = 0.69) for the T174 homozygote, and 1.19 (95% CI = 0.91-1.55, P = 0.20) for the T235 homozygote. Similarly, no significant difference was found in the frequencies of the DD genotype and the T174 and T235 homozygotes between the control group, the CAD group, the non-MI group, and the MI group when analyzed according to sex, age, or degree of risk. Our data suggest that neither the DD genotype of the ACE I/D polymorphism nor the T174 and T235 homozygotes of the AGT gene confer significant risk for CAD or MI in Chinese.

Angiotensinogen↗
PubMed1997

Interaction between obesity and genetic polymorphisms in the apolipoprotein CIII gene and lipoprotein lipase gene on the risk of hypertriglyceridemia in Chinese.

To understand the effects of the interaction between genetic polymorphisms and obesity on the risk of hypertriglyceridemia (HTG), two polymorphisms, an SstI polymorphism on the apolipoprotein CIII gene and a HindIII polymorphism on the lipoprotein lipase gene, were analyzed in 339 Chinese subjects with (82 cases in the HTG group) or without HTG (257 cases in the control group). Our data revealed that the frequencies of obesity, the SstI minor allele (S2), and the HindIII major allele (H+) in the HTG group were significantly higher than in the control group. Subgroup analysis revealed that the association between these two polymorphisms and HTG occurred predominantly in nonobese subjects and in subjects with the less hypertriglyceridemic genotype of another polymorphism. Multivariate logistic regression analysis showed that all three risk factors (obesity, S2-containing chromosome, and H+ homozygosity) were associated with HTG, and an interaction was found between obesity and H+ homozygosity for the occurrence of HTG. The risk of HTG increased significantly with combinations of risk factors. Subjects can be divided into low or high risk groups for HTG using such combinations. These results provide evidence of interaction between obesity and the HindIII polymorphism of the lipoprotein lipase gene on the risk of HTG.

Alleles↗