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Biomedical subjects

M S Chern

Publications and source records attributed to M S Chern.

At least 19 recordsLinked to original sources
PubMed2005

Sudden death in Wolff-Parkinson-White syndrome combined with syncope: a case report.

Electrocardiogram showing Wolff-Parkinson-White (WPW) pattern in an asymptomatic patient is common, but it is difficult to assess the potential risk of sudden death in such cases. Although the incidence of sudden death in these patients is extremely low, an interventional approach is suggested for all patients despite its controversial nature. Syncope, despite being induced by various mechanisms, has been considered an alarming sign of sudden death of WPW syndrome. We describe a 16-year-old female patient with an electrocardiogram that demonstrated a WPW pattern combined with unexplained syncope. None of the examinations, including biochemical profiles, brain computed tomography, transthoracic echocardiography, head-up tilt table test and exercise electrocardiogram, clarified her syncope. Consequently, no further electrophysiologic study was performed for this patient. Unfortunately, the patient suffered sudden death while running. The case highlights the need for vigilance when unexplained syncope combined with WPW syndrome. Such cases have high risk of sudden death, and thus, further interventional study and treatment is indicated.

Adolescent↗
PubMed2005

The transient appearance of collateral circulation during coronary spasm.

This article reports a case of transient augmentation of collateral circulation due to spontaneous coronary arterial spasm during angiography. The patient's electrocardiogram revealed ST-segment depression during vasospastic attack; this depression differs from the typical change of the ST-segment elevation in coronary spasm without collateral circulation.

Collateral Circulation↗
PubMed2001

Acute and long-term outcomes of stenting in coronary vessel > 3.0 mm, 3.0-2.5 mm, and < 2.5 mm.

We compared the acute and long-term outcomes of stentings in coronary vessels > 3.0 mm, 3.0-2.5 mm, and < 2.5 mm. A total of 1,152 patients underwent coronary stenting was divided into three groups based on the reference vessel size. Group A consisted of 598 patients (667 lesions) with a reference vessel diameter > 3.0 mm, group B 485 patients (544 lesions) with a reference vessel diameter of 3.0-2.5 mm, and group C 114 patients (119 lesions) with a reference vessel diameter < 2.5 mm. The procedural success, stent thrombosis, and in-hospital cardiac event rate were similar in the three groups. At 6-month angiographic follow-up, the lesion restenotic rate was significantly higher in the small-vessel group (14%, 22%, and 26% in groups A, B, and C, respectively; P = 0.011). These differences appeared to result from a lesser acute gain and a lesser net gain in small-vessel group; the late luminal loss was similar in the three groups. During a follow-up duration of 28 +/- 3 months, group C patients had a significantly lower rate of event-free survival than the group A and B patients (71% vs. 85% and 82%; P = 0.002). Stepwise regression analysis demonstrated that complex lesion (P = 0.032) and long lesion (P = 0.046) are independent predictors of restenosis in very-small-vessel (< 2.5 mm) stenting. In conclusion, the acute results of stenting in small coronary arteries appear safe and feasible with a high procedural success rate and a low incidence of stent thrombosis. Stenting in patients with a small coronary artery appears to have a similar in-hospital cardiac event rate, but a higher angiographic restenosis rate and a lower event-free survival rate, compared to stenting in patients with a larger coronary artery. The predictors of restenosis in very-small-vessel stenting are complex lesions and long lesions. Cathet Cardiovasc Intervent 2001;53:314-322.

Aged↗
PubMed2001

Evidence for a disease-resistance pathway in rice similar to the NPR1-mediated signaling pathway in Arabidopsis.

The Arabidopsis NPR1/NIM1 gene is a key regulator of systemic acquired resistance (SAR). Over-expression of NPR1 leads to enhanced resistance in Arabidopsis. To investigate the role of NPR1 in monocots, we over-expressed the Arabidopsis NPR1 in rice and challenged the transgenic plants with Xanthomonas oryzae pv. oryzae (Xoo), the rice bacterial blight pathogen. The transgenic plants displayed enhanced resistance to Xoo. RNA blot hybridization indicates that enhanced resistance requires expression of NPR1 mRNA above a threshold level in rice. To identify components mediating the resistance controlled by NPR1, we used NPR1 as bait in a yeast two-hybrid screen. We isolated four cDNA clones encoding rice NPR1 interactors (named rTGA2.1, rTGA2.2, rTGA2.3 and rLG2) belonging to the bZIP family. rTGA2.1, rTGA2.2 and rTGA2.3 share 75, 76 and 78% identity with Arabidopsis TGA2, respectively. In contrast, rLG2 shares highest identity (81%) to the maize liguleless (LG2) gene product, which is involved in establishing the leaf blade-sheath boundary. The interaction of NPR1 with the rice bZIP proteins in yeast was impaired by the npr1-1 and npr1-2 mutations, but not by the nim1-4 mutation. The NPR1-rTGA2.1 interaction was confirmed by an in vitro pull-down experiment. In gel mobility shift assays, rTGA2.1 binds to the rice RCH10 promoter and to a cis-element required sequence-specifically for salicylic acid responsiveness. This is the first demonstration that the Arabidopsis NPR1 gene can enhance disease resistance in a monocot plant. These results also suggest that monocot and dicot plants share a conserved signal transduction pathway controlling NPR1-mediated resistance.

Amino Acid Sequence↗
PubMed2001

Coronary artery calcium determined by electron beam computed tomography for predicting angiographic coronary artery disease in moderate- to high-risk Chinese patients.

The aim of this study was to evaluate the prevalence of coronary calcification among moderate- to high-risk Chinese patients and to evaluate the ability of the coronary calcium score determined by electron beam computed tomography (EBCT) to predict angiographic coronary artery disease in this population. We enrolled 163 consecutive patients and analyzed their cardiovascular risk factors, coronary calcium scores and coronary angiogram results. One hundred and twenty-five patients (76.7%) had a positive EBCT scan result (coronary calcium score >0). The prevalence of calcification and the calcium scores showed a graded relation to the number of cardiovascular risk factors and age (p < 0.001 for trend). Coronary calcium scores showed statistically significant differences between patients with angiographic evidence of coronary artery disease and patients with normal coronary angiography (p < 0.05), but could not differentiate between patients with significant and insignificant coronary artery disease. Receiver operating characteristic curve analysis showed that a coronary calcium score >5 predicted angiographic coronary artery disease with 93% sensitivity and 86% specificity (area under the curve 0.95 +/- 0.019). Multivariate analysis showed a coronary calcium score >5 to be the strongest independent predictor of angiographic coronary artery disease (odds ratio 120.7, 95% confidence interval 21.7-671.4; p < 0.001). Coronary calcium score determined by EBCT appears to have a similar predictive value in Chinese patients as it does in other ethnic populations that have been reported to date.

Adult↗
PubMed2001

Further characterization of apolipoprotein B genetic variations in Taiwanese.

Apolipoprotein B (apoB, protein; APOB, gene) is the main protein component of low-density lipoprotein (LDL) and plays an important role in blood lipid metabolism. Previously, we have reported four APOB coding regions, 5' signal peptide, and 3' repeat sequence polymorphisms in our population. In this report, we further characterize other APOB genetic variations. The results illustrate that the mutation frequencies for Arg3500Gln (1/846 alleles), Arg4019Trp (2/786 alleles), -265 C/T promoter region (0/264 alleles), and intron 2 A/G (0/450 alleles) are very low. Our population showed a frequency of 68.9% for the B4311 Ser allele. The B4311 Asn allele was associated with a higher apoB level than the Ser group (p < 0.05) in normal controls. In the normal controls, a higher B4311 Asn/Asn genotype frequency was found in the group with total cholesterol (TC) > 200 mg/dL and apoB concentration > 85 mg/dL than in the group with a TC < 200 mg/dL and apoB < 85 mg/dL (p = 0.03 for TC comparison).

Analysis of Variance↗
PubMed2001

Differential coronary artery calcification detected by electron beam computed tomography as an indicator of coronary stenosis among patients with stable angina pectoris.

BACKGROUND: The detection of coronary artery calcification by electron beam computed tomography (EBCT) has been suggested as an indicator of atherosclerosis and coronary artery disease (CAD). There is no consensus on the correlation between coronary calcification and angiographically significant stenosis on an artery-by-artery basis. OBJECTIVE: To examine the relationship between coronary calcification score (CCS) and the presence of significant CAD on an artery-by-artery basis in patients with stable angina pectoris. METHODS AND RESULTS: EBCT and coronary angiogram (CAG) were evaluated in 71 patients with stable angina and in nine control subjects. The CCSs of each of the four major coronary arteries were highest in patients with significant CAD (n=43), followed by patients with insignificant CAD (n=5), patients with syndrome X (n=23) and control subjects, respectively. Calcification scores of the four major coronary arteries appeared to have different predictive power for significant stenosis on the same vessel. For left main (LM) and left anterior descending (LAD) coronary arteries, CCSs of vessels with significant stenoses were not different from those without significant stenoses (values expressed as medians: LM 0 versus 1; LAD 98.5 versus 70; not significant). Calcification scores of left circumflex (LCX) and right coronary arteries (RCA) were significantly higher in vessels with significant stenosis (LCX 49.5 versus 0; RCA 53 versus 1; P<0.05). CCSs appeared to be moderately useful to predict significant stenoses in these two vessels (areas under receiver operating characteristic curves: LCX 0.68+/-0.08, 95% CI 0.52 to 0.81; RCA 0.71+/-0.08, 95% CI 0.55 to 0.84). CONCLUSIONS: The CCSs of RCA and LCX arteries, but not those of LM and LAD arteries, may predict significant angiographic stenosis on an artery-by-artery basis among patients with stable angina pectoris.

Aged↗
PubMed2000

A phase II trial of vinorelbine and cisplatin in previously untreated inoperable non--small-cell lung cancer.

Weekly vinorelbine injection with cisplatin had been used in treatment of non-small-cell lung cancer. We performed a phase II trial to evaluate the efficacy and toxicity of a new schedule of vinorelbine and cisplatin in patients with previously untreated, inoperable (stage IIIB or stage IV) non-small-cell lung cancer. From April 1996 to May 1997, 52 patients were enrolled for study, and 50 patients were eligible and evaluable for both response and toxicity assessment. Therapy consisted of vinorelbine, 30 mg/m2, intravenously on days 1 and 5 of a 21-day cycle, and cisplatin 100 mg/m2 (reduced to 80 mg/m2 after the first seven patients) given on day 1. A total of 211 treatment courses were administered; the median number of cycles administered per patient was 4.5 (range: 1-6), the median dose intensity for vinorelbine was 16.9 mg/m2/week (84.4%), whereas that of cisplatin was 22.8 mg/m2/week (84.7%). Twenty-five patients responded to therapy for an overall response rate of 50%; one patient attained a complete response (2%). The main toxicities were vomiting, myelosuppression, and diarrhea, which included World Health Organization grade 3 or 4 nausea/vomiting (58% patients), anemia (41% patients), neutropenia (12% patients), and diarrhea (14%). The median duration of responses was 9 months. The median time to disease progression was 6.8 months (range 0.4-18.1 months). Median survival was 13 months, and 54% of patients were alive at 1 year. We conclude that this new schedule of vinorelbine and cisplatin achieves a high response with acceptable toxicity profile in patients with advanced non-small-cell lung cancer.

Adult↗
PubMed2000

Amiodarone toxicity in a patient with simultaneous involvement of cornea, thyroid gland, and lung.

Amiodarone, an iodine-rich benzofuran derivative, is a highly effective agent for the prophylaxis and treatment of cardiac arrhythmias, but it is associated with numerous side effects. Amiodarone toxicity involving several organs simultaneously has rarely been reported heretofore. In this report, we describe a case of a 73-year-old man who developed symptomatic hypothyroidism, pulmonary toxicity, and vortex epitheliopathy of the cornea during 6 months of amiodarone therapy for frequent palpitation and angina after myocardial infarction. This case illustrates that amiodarone may cause toxicity involving several organs concurrently in a patient receiving long-term amiodarone therapy. This may be of clinical significance in managing such patients.

Aged↗
PubMed2000

Benefits of late coronary artery stenting in patients with acute myocardial infarction with and without thrombolytic therapy.

BACKGROUND: There are no added benefits when balloon angioplasty is conducted in conjunction with thrombolytic therapy in patients with acute myocardial infarction. The purpose of this study was to determine whether or not thrombolysis has an impact on the outcome of late coronary artery stenting following acute myocardial infarction. METHODS: The outcome of late coronary artery stenting in the infarct-related artery following acute infarction was compared in patients with (68 patients, group A) and without (118 patients, group B) prior thrombolytic therapy. RESULTS: The baseline characteristics were similar in the 2 groups except that total occlusion of the infarct-related artery was more common in group B. The angiographic characteristics of the target lesion were similar in the 2 groups; the procedural success rate was 98% in both groups. There was no subacute thrombosis or other complications in either group. The 6-month follow-up coronary angiography and the restenosis rate was 18% in both groups; the reocclusion rate was 2% in group A and 4% in group B. The increment of the left ventricular ejection fraction was similar in both groups (6% versus 7%). During a follow-up duration of 18 +/- 3 months, the mortality rate was 3% versus 2%, reinfarction 0% versus 1%, recurrent angina 6% versus 4%, and target lesion revascularization by angioplasty 13% versus 13% in group A and B patients, respectively. CONCLUSION: The outcome of late coronary artery stenting following acute myocardial infarction in patients with and without prior thrombolytic therapy was comparable. Significant improvement of left ventricular function was noted in both groups.

Adult↗
PubMed1999

Clinical and angiographic outcomes are similar with half, single, or multiple contiguous Palmaz-Schatz stent implantations for a single coronary stenosis.

We compared the immediate and 6-month clinical and angiographic outcomes in patients undergoing a half, a single, or multiple contiguous stent implantations for a single coronary stenosis. Four hundred forty-three consecutive patients, who underwent elective Palmaz-Schatz stent implantations for 542 stenoses between November 1995 and July 1998, were analyzed. Sixty-three patients with 78 stenoses received a half stent (group A), 346 patients with 395 stenoses received a single stent (group B), and 68 patients with 69 stenoses received multiple overlapping stents (group C) for a single coronary stenosis. Seventy-eight half stents were implanted in 78 stenoses in group A, 395 stents in 395 stenoses in group B, and 141 stents in 69 stenoses in group C. The baseline characteristics were similar in the 3 groups. There were no deaths, no subacute thrombosis, and no vascular complications. Forty-nine patients with 57 stenoses in group A, 280 patients with 326 stenoses in group B, and 59 patients with 60 stenosis in group C underwent 6-month follow-up coronary angiography; the restenotic rate per patient was 10% in group A, 20% in group B, and 24% in group C (NS); the restenotic rate per stenosis was 9% in group A, 18% in group B, and 23% in group C (NS). Follow-up of 18 +/- 3 months revealed no differences in mortality, reinfarction, recurrent angina, target narrowing angioplasty, and elective coronary artery bypass surgery among the 3 groups. The overall cardiac event-free survival was 90%, 82%, and 83% in groups A, B, and C, respectively (p = 0.275). Thus, the procedural success rate, the in-hospital morbidity, and the long-term outcome are similar with coronary stenting using a half, a single, or multiple overlapping Palmaz-Schatz stents for a single stenosis.

Angioplasty, Balloon, Coronary↗
PubMed1999

String-plucking as a mechanism of chordal rupture during balloon mitral valvuloplasty using inoue balloon catheter.

Percutaneous transvenous mitral commissurotomy using the Inoue technique was performed in a 59-year-old female with mitral stenosis and a severely calcified mitral leaflets. Although not entrapped in the subvalvular apparatus, the balloon catheter was deviated away from the mitral orifice-apex axis of the left ventricle during the inflation of the proximal balloon, which plucked and severed the chordae tendineae of the posterior mitral leaflet and resulted in severe mitral regurgitation.

Calcinosis↗
PubMed1999

Aberrant left brachiocephalic vein: CT imaging findings and embryologic correlation.

Computed tomography was utilized to evaluate aberrant left brachiocephalic vein (ALBCV), an infrequently discussed congenital vascular anomaly among Chinese people. Associated vascular variation and possible embryonic correlation are discussed. Since 1990, a total of 14 cases of ALBCV have been reported in patients receiving CT scan of chest, and was mainly an incidental diagnosis. One case was confirmed angiographically and two others were confirmed by magnetic resonance imaging. Emphasis was placed on the entry of the azygos vein into the superior vena cava (SVC), the length of the SVC, and the presence of other cardiovascular abnormalities. Of the 14 cases of ALBCV, the level of azygos vein entry was higher than the origin of the SVC in 7 cases: 4 were approximately the same level and 3 were lower. The average length of the SVC was approximately 5. 6 cm shorter than that of the general population, which is approximately 7.0 cm. Three cases had associated vascular anomaly. Most cases of ALBCV had azygos vein drainage level higher than or equal to the origin of the SVC. Right-sided aorta is one of the causes giving rise to the ALBCV during embryonic development. The CT scan remains a definitive diagnostic modality for ALBCV.

Adolescent↗
PubMed1999

Complications of Inoue balloon mitral commissurotomy: impact of operator experience and evolving technique.

BACKGROUND: There have been no single-center studies that have systematically addressed the acute outcome of Inoue balloon mitral commissurotomy (BMC) performed in a large series of patients. Accordingly, this study sought to examine the impact of operator experience and continuing technical modifications on the success and complication rates of BMC. METHODS: BMC was performed in 799 patients: 469 patients with pliable mitral valves (group 1) and 330 patients with calcified valves and/or severe subvalvular disease (group 2). Acute complications were examined and compared between groups before and after modifications in BMC techniques. Major modifications included the use of a height-derived balloon sizing method for the selection of an appropriate balloon catheter, a cautionary stepwise dilation technique, and avoidance of traction on the interatrial septum during balloon inflations. RESULTS: Technical failures were encountered in 4 (0.5%) patients in our early experience. One patient sustained cardiac perforation and tamponade and was the only case requiring emergency surgery. There were no deaths. Systemic embolic events were observed in 11 (1.4%), all among the first 353 patients before the routine use of pre-BMC transesophageal echocardiography. Severe postprocedure angiographic (>/=3+) mitral regurgitation occurred in 4% of patients, 2% in group 1 versus 9% in group 2 (P =.0001). With increased operator experience and technical modifications, this complication was significantly reduced from 5% (7 of 150 patients) to 0% in the last 316 patients in group 1 (P =.0001) and from 11% (26 of 228 patients) to 3% (3 of 101 patients) in group 2 (P =.031). The incidence of significant interatrial shunting (pulmonary-to-systemic flow ratio >/=1.3) was also significantly reduced from 12% to 6% (P =.0034). CONCLUSION: Incremental operator experience and ongoing technical refinements in BMC techniques have resulted in a 100% technical success rate and a significant diminution in complications in patients with a wide spectrum of stenotic mitral valve morphologic features.

Adolescent↗
PubMed1999

Mechanisms and clinical significance of transient atrioventricular block during dobutamine stress echocardiography.

OBJECTIVES: The purpose of this study was to investigate the possible mechanism and the clinical significance of transient atrioventricular block (AVB) during dobutamine stress echocardiography (DSE). BACKGROUND: Transient AVB occurs rarely during DSE; however, the mechanisms responsible for blocks are unclear. METHODS: A retrospective analysis of clinical, echocardiographic, catheterization, revascularization and head-up tilting test data was conducted in patients who developed transient AVB during DSE. RESULTS: A total of 302 patients with known or suspected coronary artery disease (CAD) underwent DSE before coronary angiography between November 1997 and August 1998. Transient AVB developed in 12 patients during the test. Mobitz I block was noted in six patients and Mobitz II block in the other six patients. Nine of these 12 patients were subsequently shown to have CAD and three had no significant coronary artery stenosis. Mobitz II block was observed only in patients with CAD, while Mobitz I block occurred in three patients with and three patients without CAD (p < 0.05). Eight of the nine patients with CAD underwent a successful coronary angioplasty with or without stenting and a repeat DSE revealed no recurrence of heart block except in one patient. Head-up tilting test in the 12 patients revealed a positive response in three of the nine patients with and all three patients without CAD. A negative head-up tilting test was likely to be observed in patients with, as compared with those without, CAD in this study population (p < 0.05). CONCLUSIONS: Transient AVB is not an infrequent manifestation during DSE. Both myocardial ischemia and neurally mediated vagal reflex may be responsible for this phenomenon. The development of Mobitz II block during DSE is indicative of the presence of CAD. A successful revascularization in patients with CAD who develop transient AVB may abolish this phenomenon.

Adult↗
PubMed1999

Critical appraisal of exercise variables: a treadmill study.

BACKGROUND: New criteria for diagnosing ischemic response to treadmill exercise testing (TET) have continuously been proposed. Simultaneous comparison of test performances according to these criteria is likely contributory to interpreting TET and needs to be updated time after time. This study was conducted to accomplish this end. METHODS: A comparison of test performances of various TET variables for a cohort of 107 clinical normals and 139 angiographic patients with normal resting electrocardiograms was performed. Angiographic references included enumeration of diseased coronary vessels, Gensini's and Duke's coronary scores, left ventricular wall motion score and ejection fraction at rest. RESULTS: The ST-segment-related variables (depression, integral, and heart-rate-adjusted slope or index) outdid non-ST-segment variables (changes in R amplitude, the Athens QRS score, peak exercise blood pressure increment and recovery pressure ratios; most P < 0.05) in diagnosing coronary artery disease. Among them the heart-rate-adjusted ST-segment depression performed still better. This trend was not evident in identifying left main and three-vessel disease. However, correlation to the coronary scores favored the ST-segment-related criteria (r = 0.18-0.39, P < 0.05 to P < 0.001 versus r = 0.05-0.23, NS to P < 0.01) for evaluating severity of coronary artery disease. CONCLUSIONS: For patients with normal resting electrocardiograms, the adjustment of ST-segment depression for heart rate is valuable for evaluating coronary artery disease.

Cardiac Catheterization↗
PubMed1999

Comparison of clinical efficacy and adverse effects between extended-release felodipine and slow-release diltiazem in patients with isolated systolic hypertension.

BACKGROUND: Isolated systolic hypertension (ISH) is a risk factor for cardiovascular disease. Extended-release felodipine (felodipine ER) has been shown to be effective in the treatment of ISH in Caucasians. However, its pharmacological properties are different from another calcium blocker, diltiazem. Also, the effectiveness, tolerability, and adverse reactions of these two antihypertensive agents for ISH have not been thoroughly assessed in Chinese. METHODS: Sitting blood pressures (BP), heart rate, body weight, adverse reactions, and serum biochemistry were assessed in 70 patients with isolated systolic hypertension (34 treated with felodipine ER and 36 slow-release diltiazem [diltiazem SR] for 10 weeks). Each patient was given 5 mg of felodipine ER or 90 mg of diltiazem SR once daily and was doubled to twice daily if necessary. RESULTS: Five patients on felodipine ER and four on diltiazem SR withdrew because of intolerable side effects. By ten weeks, 67.6% of the patients responded to a daily dose of 5-10 mg of felodipine ER and 58.3% to a daily dose of 90-180 mg of diltiazem SR. At the end of treatment, felodipine ER lowered the mean BP from 187/83 mmHg at baseline to 149/74 mmHg, whereas diltiazem SR decreased the BP from 185/84 mmHg to 158/78 mmHg (not significant between the two groups). The heart rate did not change significantly in either group. Overall, these two groups of patients had the same rate of adverse reactions (50.0% vs. 50.0%) with similar profiles of the adverse effects. CONCLUSION: Equivalent doses of felodipine ER and diltiazem SR are effective first-line monotherapeutic agents for the treatment of ISH.

Adult↗