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Biomedical subjects

K W Lau

Publications and source records attributed to K W Lau.

At least 19 recordsLinked to original sources
PubMed2004

Willingness to donate blood samples for genetic research: a survey from a community in Singapore.

Studies on the public's willingness to donate blood specimens for genetic research are few and are conducted mainly among Western countries. Little is known about the Asian community's willingness to participate in genetic research. A community-based survey was conducted on 548 adult Singaporeans to examine their willingness to donate blood samples for genetic research and its associated factors. The response rate was 70.3%. About 49.3% (95% CI, 45.1-53.5%) were willing to donate blood for genetic research. In the multivariable Cox regression analysis, willingness was significantly associated with belief in the benefits of genetic research; intention to participate in government studies; having no fear of pain, blood, injections, and needles; and non-concern about the loss of confidentiality. Reasons against donating blood were fear of pain, blood, injections, and needles (38.1%); no self-benefits (24.8%); fear of finding out about having a disease (22.3%); fear of discrimination (18.7%); and concerns about weakness (15.1%) and weight gain (9.4%). Public education programs to promote participation in genetic research should stress its benefits and address people's fears and concerns.

Adult↗
PubMed2004

A stent is not just a stent: Stent construction and design do matter in its clinical performance.

The undisputed superiority of stents over conventional balloon angioplasty has resulted in a plethora of stents in clinical use. Recent data, however, have indicated not all stent models are the same. Nuances in stent design and construction have impacted significantly on the immediate and long-term clinical outcome. Among the stainless steel stents, those with multicellular or tubular designs have proven to be superior to coiled or hybrid stent models, and thin-strut stents perform better than thicker-strut stents. Coating stainless steel stents with gold, carbide, phosphorylcholine or heparin do not appear to confer any additional benefit, compared with bare metal stents. In contrast, randomised trials have demonstrated that drug-eluting stents coated with various anti-proliferative drugs, with or without a carrier polymer, afford unparalleled restenosis rates compared with non-drug-eluting stents. Drug-eluting stents, however, are expensive, and their long-term durability and safety remain undefined. Notwithstanding these unresolved issues, it is likely that the majority of percutaneous coronary interventions will involve the use of drug-eluting stents once a more attractive balance between their cost and clinical effects is reached.

Angioplasty, Balloon, Coronary↗
PubMed2002

Clinical outcomes of patients with diabetes mellitus and acute myocardial infarction treated with primary angioplasty or fibrinolysis.

OBJECTIVE: To compare the early and late outcomes of primary percutaneous transluminal coronary angioplasty (PTCA) with fibrinolytic treatment among diabetic patients with acute myocardial infarction (AMI). DESIGN: Retrospective observational study with data obtained from prospective registries. SETTING: Tertiary cardiovascular institution with 24 hour acute interventional facilities. PATIENTS: 202 consecutive diabetic patients with AMI receiving reperfusion treatment within six hours of symptom onset. INTERVENTIONS: Fibrinolytic treatment was administered to 99 patients, and 103 patients underwent primary PTCA. Most patients undergoing PTCA received adjunctive stenting (94.2%) and glycoprotein IIb/IIIa inhibition (63.1%). MAIN OUTCOME MEASURES: Death, non-fatal reinfarction, and target vessel revascularisation at 30 days and one year were assessed. RESULTS: Baseline characteristics were similar in these two treatment groups except that the proportion of patients with Killip class III or IV was considerably higher in those treated with PTCA (15.5% v 6.1%, p = 0.03) and time to treatment was significantly longer (103.7 v 68.0 minutes, p < 0.001). Among those treated with PTCA, the rates for in-hospital recurrent ischaemia (5.8% v 17.2%, p = 0.011) and target vessel revascularisation at one year (19.4% v 36.4%, p = 0.007) were lower. Death or reinfarction at one year was also reduced among those treated with PTCA (17.5% v 31.3%, p = 0.02), with an adjusted relative risk of 0.29 (95% confidence interval 0.15 to 0.57) compared with fibrinolysis. CONCLUSION: Among diabetic patients with AMI, primary PTCA was associated with reduced early and late adverse events compared with fibrinolytic treatment.

Abciximab↗
PubMed2002

Coronary artery bypass grafts in situs inversus.

Coronary artery bypass grafting in dextrocardia is rare. A case is described for the first time where both arterial and venous conduits were used. The subtle changes required in the conduct of the operation are highlighted.

Aged↗
PubMed2002

An interesting case of left atrial myxoma.

Myxoma is the most common type of primary tumours of the heart in adults. Majority of these myxomas are found in the left atrium, followed by the right atrium and ventricles. We describe herein a patient who had a left atrial myxoma with interesting investigational results.

Aged↗
PubMed2001

Frequent loss of heterozygosity on multiple chromosomes in Chinese esophageal squamous cell carcinomas.

Analysis of the loss of heterozygosity (LOH) detected by polymerase chain reaction techniques using 18 polymorphic markers localized to chromosomes 3p, 5, 17, and 18q in 40 Hong Kong Chinese esophageal squamous cell carcinoma (ESC) patients showed that multiple alterations on several chromosomes are involved in ESC development. The LOH rates detected for markers on chromosome 3 ranged from 44.0 to 85.7%, for chromosome 5 from 40.9 to 61.9%, for chromosome 17 from 40.0 to 100%, and for chromosome 18 from 38.9 to 58.3%. No significant association was observed between LOH and the clinical and histopathological parameters.

Aged↗
PubMed2001

Myelodysplasia, hypophosphataemia, vitamin D and iron deficiency in an alpaca.

A pregnant 2-year-old alpaca was presented for evaluation of progressive weight loss, decreased appetite and lethargy that developed in winter. Haematologic and serum biochemical analyses revealed marked anaemia, leukopenia, severe hypophosphataemia and mild hypocalcaemia. Evaluation of bone marrow core biopsies and aspirates revealed an increased proportion of immature haematopoietic cells, without sufficient numbers of blast cells to be termed an acute myeloid leukaemia (AML). 1 The haematological and bone marrow findings were suggestive of myelodysplastic syndrome (MDS). The anaemia, leukopenia, lethargy and weight loss remained refractory to medical therapy and the alpaca was euthanased on humane grounds.

Anemia, Iron-Deficiency↗
PubMed2000

Mid-term clinical and angiographic follow-up outcome after placement of a new balloon expandable stent in native coronary arteries.

The widely disparate characteristics that exist among the different stent designs currently available for clinical use may impact on their acute and late angiographic and clinical results. The BeStent (Medtronic Instent, MN) is a relatively new stainless steel, laser-cut, serpentine stent design with only very limited data regarding its performance. In this report, we examined the results of 74 consecutive patients (54 men, 20 women; mean age, 58 years) treated with 76 BeStents in 75 native coronary arteries with a mean reference size of 2.8 mm. Successful stenting without 30-day major adverse cardiac complications was achieved in 97.3% of procedures, resulting in a significant improvement in diameter stenosis from 85% to 2% (P = 0.0001). Six-month angiographic restudy in 88% of patients revealed a per-lesion in-stent restenosis rate of 27%. At a mean follow-up period of 9.3 months, there were no deaths or myocardial infarctions. In summary, the present study demonstrates that the BeStent has an excellent performance profile, is associated with a low risk of stent thrombosis, and yields an acceptable restenosis rate despite the inclusion of a high proportion of patients with diabetes (41%) and small vessels (< 3.0 mm in diameter; 77%).

Aged↗
PubMed2000

Stent placement for non-STRESS/BENESTENT lesions: a critical review.

Stenting lesions with favorable characteristics as required for inclusion in the STRESS/BENESTENT trials have yielded superior results to that of PTCA alone. Results for less favorable lesions such as in small vessels, diffuse disease, ostial disease, and saphenous vein grafts are less well established. This review seeks to analyze available data for stent placement in this subset of non-STRESS/BENESTENT lesions.

Angioplasty, Balloon, Coronary↗
PubMed2000

Clinical and angiographic outcome after angiography-guided stent placement in small coronary vessels.

BACKGROUND: Although it is widely accepted that stenting confers favorable angiographic and clinical results in coronary arteries >/=3.0 mm in diameter, the outcome of stent placement in smaller vessels remains largely unclear. METHODS AND RESULTS: We sought to specifically determine the early and long-term clinical outcomes in a large series of 197 consecutive patients who underwent stent placement in 207 vessels <3.0 mm in diameter. Procedural success, accomplished in 97.3%, was accompanied by a significant reduction in lesion severity from 85% +/- 9% before to 3% +/- 7% diameter stenosis after the procedure (P =.0001) and a 0.5% incidence of subacute stent thrombosis. At 1 and 2 years of follow-up, survival rate without major target lesion-driven events was observed in 77.3% and 73.9% of patients, respectively. Repeat revascularization procedures accounted for most of these events; cardiac deaths (including those related to subacute stent thrombosis) and late (>30 days) myocardial infarctions were infrequent (2.4% and 1.0%, respectively). The 6-month angiographic binary instent restenosis rate was 30.1%. On multivariate analysis, diabetes mellitus (P =. 0275), small baseline reference vessel size (P =.0300), and stent size </=2.7 mm (P =.0111) were independently associated with an increased instent restenosis rate. CONCLUSIONS: Optimal angiography-guided coronary stenting of vessels <3.0 mm in diameter in association with the stringent use of a poststent combined aspirin-ticlopidine antiplatelet regimen confers a low risk of stent thrombosis, an acceptable incidence of angiographic instent restenosis, and a favorable long-term clinical outcome.

Aged↗
PubMed2000

Redox modulation of chloroplast DNA replication in Chlamydomonas reinhardtii.

We constructed a plasmid probe containing DNA sequences unique for chloroplast (Cp) genome and nuclear genome of Chlamydomonas reinhardtii. Using this probe and quantitative Southern blot analyses, we determined the content ratio of Cp DNA/nuclear DNA in total DNA isolated from cells grown in different conditions. Algal cells grown photoheterotrophically with acetate as an added carbon source contain the highest amount of Cp DNA compared with cells grown in other conditions tested. We investigated the effect of nitrogen limitation, 5-fluorodeoxyuridine treatment, cadmium exposure, photoautotrophic growth, and heterotrophic growth in darkness. The change in the Cp/nuclear DNA ratio in cells shifted from one growth condition to another depended on cell division; Cp DNA content in undivided cells remained constant. Therefore, the reduction of Cp DNA content was attributed by under replication rather than selective degradation of Cp DNA. Cells with low Cp DNA content often contained less reduced glutathione, suggesting the possible effect of redox status. Low Cp DNA content was detected in cells treated with inhibitors that block electron flow of photosystems and in mutants with PS I defective phenotype. On the basis of these data, we propose that in C. reinhardtii, Cp DNA replication be modulated by redox status.

Acetates↗
PubMed2000

Percutaneous interventional strategies in the treatment of chronic total coronary occlusions.

Chronic total coronary occlusions which make up 10% to 20% of all interventional procedures in high-volume centres remain a vexing problem for invasive cardiologists for 2 main reasons. First, they are only successfully recanalised in about 60% of attempts with most failures resulting from an inability to cross the lesions. Laser guidewire appears to be a promising innovation in overcoming this obstacle. Second, after initially successful recanalisation with conventional balloon angioplasty (PTCA), a high restenosis rate (range, 45% to 75%) is observed. Stent placement, by conferring maximal luminal expansion, appears to have resolved this problem to a large extent; both observational and randomised studies indicate that after stent placement, restenosis rate is at least halved that of PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1999

Genomic instability and alterations in Apc, Mcc and Dcc in Hong Kong patients with colorectal carcinoma.

Our aim was to reveal the significance of tumor-suppressor genes and genomic instability in 99 Hong Kong Chinese colorectal carcinoma (CRC) patients by PCR-LOH analysis and PCR-PTT assay. The frequencies of allelic loss of Apc, Mcc and Dcc and of APC truncation were 31.3% (15/48), 11.6% (5/43), 44.4% (20/45) and 46/93 (49.5%), respectively. The frequency of Apc LOH was similar to, the Mcc LOH was lower than, and the Dcc LOH was higher than that reported for Caucasians and Japanese. In Hong Kong CRC patients, the replication error-positive (RER(+)) phenotype occurred with a frequency of 10% (10/99), which was similar to other results using microsatellite markers where RER(+) frequencies ranged from 11% to 28%. The rates of genetic alteration in RER(+) tumors were lower in tumors harboring p53, Mcc and Dcc alterations; similar in Apc; and higher in Ki-ras tumors compared with RER(-) tumors, though these differences did not achieve statistical significance. None of the biomarkers examined were predictive of survival independently, but strong trends confirming earlier observations of associations between RER(+) phenotypes with proximal tumor location and poorly differentiated tumor status were noted. The RER(+) phenotype was correlated significantly to the less aggressive Duke's stage B and improved prognosis. Additionally, tumors with RER(+) phenotypes were positively correlated with young age and sex. Our results support the observation that a subset of younger male CRC patients in Hong Kong may develop CRC via the RER pathway and show differences in RER status and sex. A significantly higher percentage of older Hong Kong Chinese CRC patients had APC truncations. Int. J. Cancer (Pred. Oncol.) 84:404-409, 1999.

Adenocarcinoma↗
PubMed1999

Angiographic restenosis rate in patients with chronic total occlusions and subtotal stenoses after initially successful intracoronary stent placement.

The 5-month angiographic in-stent restenosis rate did not differ between patients with chronic total occlusions (n = 43) and subtotal stenoses (n = 43) equally matched for diabetes status, exact stent design, final expanded stent diameter, stent length, and residual percent diameter stenosis after stent placement; it was 32.5% and 27.9% for those with chronic total occlusions and subtotal stenoses, respectively (p = 0.638). Furthermore, the stent occlusion rate (4.6% vs 6.9%, respectively) was low in both patient groups.

Angioplasty, Balloon, Coronary↗
PubMed1999

Immediate and mid-term results after MultiLink stent implantation in native coronary arteries.

Different stent designs have widely disparate characteristics that may exert a positive or negative impact on their early and mid-term outcomes. The MultiLink stent (Guidant/Advanced Cardiovascular Systems, Santa Clara, CA) is a new coronary stent with only very limited data. In this report, we examined the results of 50 consecutive patients treated with 57 premounted sheathless MultiLink stents in 53 native coronary arteries with reference diameter > or =2.7 mm. Successful stenting was achieved in 98% of patients, resulting in an improvement in diameter stenosis from 91%+/-11% to 1%+/-3% (P = 0.0001). At 1 month, there was no death, myocardial infarction, or stent thrombosis. Angiographic restudy at a mean of 5.0+/-1.8 months in 94% of patients revealed an in-stent restenosis rate of 20.7%. The restenosis rates for diabetic patients (vs. nondiabetic patients), type C lesions (vs. type A/B1 lesions), and the use of 35-mm-long stents (vs. 15-mm-long stents) were 45.4% (14.3%), 56% (< or =11%), and 80% (8.8%), respectively (P < 0.05). In conclusion, the present study demonstrates that the MultiLink stent has an excellent performance profile, is associated with a low risk of stent thrombosis in native coronary vessels, and yields a favorable restenosis rate, particularly after the use of short (15 mm) stents to treat simple lesions.

Aged↗
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↗