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Biomedical subjects

K L Lee

Publications and source records attributed to K L Lee.

At least 19 recordsLinked to original sources
PubMed2006

Contamination of mercury in tongkat Ali hitam herbal preparations.

The DCA (Drug Control Authority), Malaysia has implemented the phase three registration of traditional medicines on 1 January 1992. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation found in Malaysia, containing tongkat Ali hitam, either single or combined preparations, were analyzed for the presence of a heavy toxic metal, mercury, using atomic absorption spectrophotometer, after performing a simple random sampling to enable each sample an equal chance of being selected in an unbiased manner. Results showed that 26% of these products possessed 0.53-2.35 ppm of mercury, and therefore, do not comply with the quality requirement for traditional medicines in Malaysia. The quality requirement for traditional medicines in Malaysia is not exceeding 0.5 ppm for mercury. Out of these 26 products, four products have already registered with the DCA, Malaysia whilst the rest, however, have not registered with the DCA, Malaysia.

Drug Contamination↗
PubMed2006

A case of takotsubo cardiomyopathy: transient left ventricular apical ballooning.

A 78-year-old woman was admitted to hospital with central chest pain and the electrocardiographic and cardiac marker changes typical of acute anterior myocardial infarction. Coronary angiography revealed normal epicardial coronary arteries, and left ventriculography showed apical akinesis as well as basal hyperkinesis. This is a case of transient left ventricular apical ballooning or takotsubo cardiomyopathy, possibly attributable to catecholamine-mediated myocardial stunning.

Aged↗
PubMed2005

A comparison of outcomes after indocyanine green and trypan blue assisted internal limiting membrane peeling during macular hole surgery.

AIMS: To compare the anatomical and visual outcomes of macular hole repair surgery using indocyanine green (ICG) or trypan blue (TB) staining of the internal limiting membrane (ILM). METHOD: Retrospective analysis of 37 eyes from 37 consecutive patients with stage 2, 3, and 4 idiopathic macular holes who underwent macular hole repair by one surgeon using the same technique but utilising different dyes for ILM peeling. In 19 patients ICG was used while 18 patients had TB. The anatomical and visual results in these two groups were compared. RESULTS: There were no significant differences in the demographic and macular hole characteristics of the ICG and TB groups. Macular hole closure was achieved in 91.9% of all patients of which the ICG group had an 89.5% hole closure rate and the TB group had a 94.4% hole closure rate. After excluding cases with failed hole closure and other vision affecting complications, there was no significant difference between the preoperative visual acuities in the TB and ICG groups but the postoperative visual acuities were better in the TB than the ICG group (p = 0.036). The TB group also had more Snellen lines of improvement than the ICG group (2.94 v 1.79 lines; p = 0.046). CONCLUSION: TB appears to be less toxic than ICG when used in dye assisted peeling of ILM during macular hole repair as reflected by the better visual results in the TB group of patients.

Aged↗
PubMed2004

Determination of lead in Smilax myosotiflora herbal preparations obtained in Malaysia.

The DCA (Drug Control Authority), Malaysia implemented the phase 3 registration of traditional medicines on 1 January 1992 with special emphasis on the quality, efficacy and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicinal preparations. As such, a total of 100 traditional medicinal preparations, containing Smilax myosotiflora, in various pharmaceutical dosage forms, which were bought in the Malaysian market, were analysed for lead content using atomic absorption spectrophotometry. Results showed that 15% of the products analysed possessed 10.23-23.05 ppm of lead, and therefore, do not comply with the quality requirement for traditional medicines in Malaysia. The quality requirement for traditional medicines in Malaysia is that they should not exceed 10 ppm of lead. Out of these 15 products, five products exhibited 10.23-23.05 ppm of lead, in fact they have already been registered with the DCA Malaysia. However, the rest of the products, which possessed 12.24-20.72 ppm of lead, have still not been registered with the DCA Malaysia. Although this study successfully showed that only 85% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to lead, they cannot, however, be assumed to be safe from lead contamination because of batch-to-batch inconsistency.

Drug Contamination↗
PubMed2004

Experimental studies of the material properties of the forewing of cicada (Homóptera, Cicàdidae).

Detailed investigations on the structural and mechanical properties of the forewing of the cicada were carried out. Measurement of the structures of the wings showed that the thickness of the membrane of each cell and the diameter of each vein were non-uniform in both the longitudinal and transverse directions, and their means were approximately 12.2 and 133.3 microm, respectively. However, the aspect ratios of the wings and the bodies were quite uniform and were approximately equal to 2.98 and 2.13, respectively. Based on the measured thickness, mass and area of the membranes of the cells, the mean density and the mean area density of the wing were approximately 2.3 g cm(-3) and 2.8x10(-3) g cm(-2), respectively. In addition, the diameters of the veins of the wings, including the diameters of the holes in the vein of the leading edge, were examined. The mechanical properties of the wing were investigated separately by nanoindentation and tensile testing. The results indicated that the mean Young's modulus, hardness and yield stress of the membranes of the wings were approximately 3.7 GPa, 0.2 GPa and 29 MPa, respectively, and the mean Young's modulus and strength of the veins along the direction of the venation of wings were approximately 1.9 GPa and 52 MPa, respectively. Finally, the relevant results were briefly analyzed and discussed, providing a guideline to the biomimetic design of the aerofoil materials of micro air vehicles.

Animals↗
PubMed2002

Effect of Eurycoma longifolia Jack on orientation activities in middle-aged male rats.

The effects of various fractions of Eurycoma longifolia Jack were studied on the orientation activities of the inbred, adult middle-aged Sprague-Dawley rats, 9 months old and retired breeders towards the receptive females (anogenital sniffing, licking, mounting), the environment (climbing, raring, exploration), themselves (nongenital grooming, genital grooming) and mobility (restricted, unrestricted) after treating these subjects twice daily for 10 days. Results showed that subjects treated with 800 mg/kg of E. longifolia Jack increased orientation activities towards the receptive females (anogenital sniffing, licking and mounting), increased genital grooming towards themselves and restricted movements to a particular area of the cage but decreased interest in the external environment (climbing, raring, exploration) as compared with the controls during the investigation period. In conclusion, this study gives further evidences that different fractions of E. longifolia Jack modified the orientation activities of the middle-aged male rats.

Animals↗
PubMed2001

Using observational data to estimate prognosis: an example using a coronary artery disease registry.

With the proliferation of clinical data registries and the rising expense of clinical trials, observational data sources are increasingly providing evidence for clinical decision making. These data are viewed as complementary to randomized clinical trials (RCT). While not as rigorous a methodological design, observational studies yield important information about effectiveness of treatment, as compared with the efficacy results of RCTs. In addition, these studies often have the advantage of providing longer-term follow-up, beyond that of clinical trials. Hence, they are useful for assessing and comparing patients' long-term prognosis under different treatment strategies. For patients with coronary artery disease, many observational comparisons have focused on medical therapy versus interventional procedures. In addition to the well-studied problem of treatment selection bias (which is not the focus of the present study), three significant methodological problems must be addressed in the analysis of these data: (i) designation of the therapeutic arms in the presence of early deaths, withdrawals, and treatment cross-overs; (ii) identification of an equitable starting point for attributing survival time; (iii) site to site variability in short-term mortality. This paper discusses these issues and suggests strategies to deal with them. A proposed methodology is developed, applied and evaluated on a large observational database that has long-term follow-up on nearly 10 000 patients.

Analysis of Variance↗
PubMed2001

The human HMGB1 promoter is modulated by a silencer and an enhancer-containing intron.

The highly conserved, ubiquitous high mobility group protein HMGB1 (formerly named as HMG1) is an architectural transcription factor encoded by a single functional gene in human. HMGB1 is expressed in almost all cell or tissue types studied. In general, it is expressed at a basal level in most cells but at a slightly elevated level of 2--3-fold in actively proliferating tissues or estrogen stimulated breast cancer cells. To understand the regulatory mechanism controlling expression of the human HMGB1 gene, we cloned and analyzed the upstream region as well as the first intron of this gene. We found that transcription of the human HMGB1 gene in the breast cancer MCF-7 cells starts at one major site 57 nucleotides upstream from the first exon-intron boundary. Expression of the human HMGB1 gene is under the control of a very strong TATA-less promoter, which has an activity more than 18-fold that of the SV40 promoter. Immediately upstream, a silencer element is present. This silencer can repress the activity of the HMGB1 promoter down to just one-sixth. The first intron of the human HMGB1 gene contains enhancer elements, which can increase the human HMGB1 promoter activity by 2--3-fold. We postulate that the human HMGB1 gene is capable of being expressed at a very high level. The basal level of expression observed in most cells is probably a result of the strong promoter being held in check by the silencer. The 2--3-fold increase in HMGB1 expression observed in proliferating cells or breast cancer cells stimulated by estrogen may probably result from the action of the enhancer elements in intron 1.

Base Sequence↗
PubMed2001

Prediction of long-term outcomes by signal-averaged electrocardiography in patients with unsustained ventricular tachycardia, coronary artery disease, and left ventricular dysfunction.

BACKGROUND: An abnormal signal-averaged ECG (SAECG) is a noninvasive marker of the substrate of sustained ventricular tachycardia after myocardial infarction. We assessed its prognostic ability in patients with asymptomatic unsustained ventricular tachycardia, coronary artery disease, and left ventricular dysfunction. METHODS AND RESULTS: A blinded core laboratory analyzed SAECG tracings from 1925 patients in a multicenter trial. Cox proportional hazards modeling was used to examine individual and joint relations between SAECG variables and arrhythmic death or cardiac arrest (primary end point), cardiac death, and total mortality. We also assessed the prognostic utility of SAECG at different levels of ejection fraction (EF). A filtered QRS duration >114 ms (abnormal SAECG) independently predicted the primary end point and cardiac death, independent of clinical variables, cardioverter-defibrillator implantation, and antiarrhythmic drug therapy. With an abnormal SAECG, the 5-year rates of the primary end point (28% versus 17%, P=0.0001), cardiac death (37% versus 25%, P=0.0001), and total mortality (43% versus 35%, P=0.0001) were significantly higher. The combination of EF <30% and abnormal SAECG identified a particularly high-risk subset that constituted 21% of the total population. Thirty-six percent and 44% of patients with this combination succumbed to arrhythmic and cardiac death, respectively. CONCLUSIONS: SAECG is a powerful predictor of poor outcomes in this population. The noninvasive combination of an abnormal SAECG and reduced EF may have utility in selecting high-risk patients for intervention.

Coronary Disease↗
PubMed2001

Electrophysiologic and clinical effects of angiotensin-converting enzyme inhibitors in patients with prior myocardial infarction, nonsustained ventricular tachycardia, and depressed left ventricular function. MUSTT Investigators. Multicenter UnSustained Tachycardia Trial.

Angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce sudden cardiac death and all-cause mortality. They also may have direct antiarrhythmic properties. We retrospectively analyzed the data from the Multicenter UnSustained Tachycardia Trial (MUSTT), to determine the effects of ACE inhibitors on inducibility of sustained ventricular tachycardia and on sudden cardiac death and overall mortality in 2,087 patients with prior myocardial infarction, nonsustained ventricular tachycardia, and depressed left ventricular function. Results of electrophysiologic testing were compared by use of ACE inhibitors at baseline, and outcomes were compared between the 564 patients prescribed ACE inhibitors at discharge and the 1,523 patients who did not receive treatment. The inducibility of sustained ventricular tachycardia during electrophysiologic testing did not differ by baseline ACE inhibitor use (unadjusted p = 0.75). Patients discharged from hospital on ACE inhibitors had a lower ejection fraction, more extensive coronary artery disease, and fewer previous revascularizations at baseline. After adjustments for differences in baseline factors and initial hospitalization variables, there were no significant differences in total mortality (p = 0.47) or arrhythmic death or cardiac arrest (p = 0.51) with ACE inhibitor use at discharge over a median 43 months of follow-up.

Aged↗
PubMed2001

Should all implantable cardioverter defibrillators for ventricular arrhythmias be dual-chamber devices?

The advantages of a dual-chamber implantable cardioverter defibrillator (ICD) over a single-chamber ICD include physiologic pacing capability, atrial electrogram storage, enhanced arrhythmia discrimination algorithms, and a potential to treat atrial arrhythmia by pacing or defibrillation. Current evidence supports the supposition that dual-chamber ICDs are definitely indicated in patients who have a concomitant indication for physiologic pacing, such as bradycardia or bradycardia-dependent ventricular tachyarrhythmias. Refined dual-chamber arrhythmia discrimination algorithms and enhanced atrial therapies are probably required for patients with frequent supraventricular arrhythmias. Furthermore, in patients with systolic heart failure, low ejection fraction, and intraventricular conduction delay, triple-chamber ICDs with biventricular pacing may improve their functional status and prevent sudden arrhythmic death. Careful patient selection is required to optimize the cost-effectiveness of these sophisticated technologies.

Arrhythmias, Cardiac↗
PubMed2001

Dietary trial in prostate cancer: Early experience and implications for clinical trial design.

Much epidemiologic and case-controlled evidence suggests that diet may be a modifier of prostate cancer risk. However, the role of dietary modification in men known to have prostate cancer is a matter of some debate. To elucidate the effect of diet and comprehensive lifestyle changes on cancer risk, we are conducting a randomized, prospective clinical trial on men with clinically localized prostate cancer who have selected "watchful waiting" as primary therapy. Since its inception in April 1997, 93 men have been randomized to control (n = 47) or dietary and lifestyle intervention (n = 46). Patients in the intervention group are asked to eat a low-fat, soy-supplemented vegan diet and take part in stress management, psychosocial group support, and exercise programs. After 1 year, adherence to all four interventions was greater than 80%, and no deaths or adverse outcomes have occurred. To date, we have collected prostate-specific antigen and endorectal magnetic resonance imaging and spectroscopy data on 63 patients (34 control and 29 intervention). This study demonstrates that a randomized, prospective dietary trial for men with localized prostate cancer is safe and feasible. The methodologies used provide insights into practical aspects of diet design and compliance assessment that may be useful templates for future dietary trials.

Diet, Vegetarian↗
PubMed2001

Differences in inducibility and prognosis of in-hospital versus out-of-hospital identified nonsustained ventricular tachycardia in patients with coronary artery disease: clinical and trial design implications.

OBJECTIVES: The goal of this study was to describe the influence of the clinical setting (in-hospital vs. out-of-hospital) in which nonsustained ventricular tachycardia (NSVT) is discovered on the rate of inducibility of sustained ventricular tachycardia (VT), arrhythmic events and survival in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction. BACKGROUND: In-hospital presentation of sustained VT is independently associated with lower long-term overall survival. The impact of the clinical setting in which NSVT is documented is unknown. METHODS: In the Multicenter Unsustained Tachycardia Trial (MUSTT), designed to assess the benefit of randomized antiarrhythmic therapy guided by electrophysiologic testing in patients with asymptomatic NSVT, CAD and LV dysfunction, eligible patients were enrolled irrespective of the setting in which the index arrhythmia was discovered. In this retrospective analysis, we compared the rate of VT inducibility and outcome of MUSTT-enrolled patients with in-hospital versus out-of-hospital presentation of NSVT. RESULTS: Monomorphic sustained VT was induced in 35% and 28% of the patients whose index NSVT occurred in-hospital and out-of-hospital, respectively (adjusted p = 0.006). Cardiac arrest or death due to arrhythmia at two- and five-year follow-ups were 14% and 28% for untreated patients with in-hospital-identified NSVT and 11% and 21% for the out-of-hospital group (adjusted p = 0.10). Overall mortality rates at two- and five-year follow-ups were 24% and 48% for inpatients and 18% and 38% for outpatients (adjusted p = 0.018). In patients randomized to antiarrhythmic therapy, there was no significant interaction between patient status (in-hospital vs. out-of-hospital) and treatment impact on the rates of total mortality (p = 0.98) and arrhythmic events (p = 0.08). CONCLUSIONS: In patients with CAD and impaired LV function, asymptomatic NSVT identified in-hospital, compared with that identified out-of-hospital, is associated with a higher rate of induction of sustained VT and overall mortality. Therefore, in similar patients, the clinical setting in which NSVT is discovered should be taken into account when formulating patient risk, treatment and clinical trial design.

Aged↗
PubMed2001

P wave polarity during pacing in pulmonary veins.

INTRODUCTION: Recent studies have demonstrated that premature depolarizations that trigger atrial fibrillation often arise in pulmonary veins. The purpose of this study was to evaluate whether P wave polarity is helpful in distinguishing which of the 4 pulmonary veins is the site of origin of a premature depolarization. METHODS AND RESULTS: In 28 patients without structural heart disease who underwent focal ablation of paroxysmal atrial fibrillation, P wave polarity on a 12-lead electrocardiogram (ECG) was analyzed during sinus rhythm, and during pacing at a cycle length of 500--600 ms in the high right atrium and within each of the 4 pulmonary veins. P waves were categorized as positive, negative, biphasic or isoelectric. A negative or biphasic P wave in lead I (sensitivity 85 %, specificity 71 %) or a positive P wave in V1 (sensitivity 85 %, specificity 89 %) were helpful in predicting a pulmonary venous site of origin as opposed to a right atrial site of origin. A positive P wave in lead II and III distinguished superior from inferior pulmonary veins (sensitivity 90 %, specificity 84 %). The sensitivity and specificity of negative or biphasic P waves in lead aVL in distinguishing a left from right pulmonary vein site of origin were 94 % and 42 %, respectively. CONCLUSIONS: Analysis of P waves polarity may be helpful in localizing the pulmonary vein that is the site of origin of a premature depolarization. Among the 12 ECG leads, I, II, III, aVL, and V1 are the most helpful in regionalizing premature depolarizations arising in the pulmonary veins.

Adult↗