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Biomedical subjects

B M Y Cheung

Publications and source records attributed to B M Y Cheung.

At least 19 recordsLinked to original sources
PubMed2006

Intron 2 (T/C) CYP46 polymorphism is associated with Alzheimer's disease in Chinese patients.

BACKGROUND: Cholesterol metabolism has been implicated in the pathophysiology of Alzheimer's disease (AD), and cholesterol-related genes are plausible candidate genes for AD. Genetic association of CYP46A1 polymorphisms with AD had been under extensive investigations; however, observations on intron 2 T-->C (rs754203) generated inconclusive results. OBJECTIVE: To analyse an independent data set in a Chinese population to see whether the polymorphic site rs754203 of the CYP46A1 gene is associated with AD. METHODS: We analysed 130 sporadic AD patients and 110 healthy controls of the Southern Chinese origin. RESULTS: An association between the genotype frequency and AD was suggested in the general population (p = 0.047, odds ratio, OR = 1. 61, 95% confidence interval, CI = 0.96-2.70), while the association was most significant in the apolipoprotein E (ApoE) epsilon4-negative group (p = 0.004, OR = 2.54, 95% CI =1.31-4.95). Linkage disequilibrium block prediction results also favoured this association. Consistent with previous reports, intron 3 C-->T (rs4900442) polymorphism did not show any evidence of association; in our data set ApoEepsilon4 was confirmed to be a genetic risk factor for AD (p = 0.0016, OR = 2.76, 95% CI = 1.50-5.11).

Aged↗
PubMed2006

Polymorphisms of the gene encoding adiponectin and glycaemic outcome of Chinese subjects with impaired glucose tolerance: a 5-year follow-up study.

AIMS/HYPOTHESIS: Polymorphisms of the gene encoding adiponectin (ADIPOQ) have previously been associated with type 2 diabetes in Europid and Japanese subjects, but not in Pima Indians. The aim of this study was to determine the contribution made by ADIPOQ gene variants to glycaemic status in southern Chinese individuals. SUBJECTS AND METHODS: Sixty unrelated subjects were screened for single-nucleotide polymorphisms (SNPs) in the ADIPOQ gene by direct sequencing. The association of tagging SNPs with the outcome of glycaemic status in 262 subjects with impaired glucose tolerance (IGT) was examined in a 5-year prospective study. RESULTS: We identified 15 polymorphisms in the ADIPOQ gene, ten of them constituting the tagging SNPs. At 5 years, 39.7% of the subjects with IGT had regressed to NGT, 41.2% had persistent IGT or impaired fasting glucose and 19.1% had developed diabetes. Only the T45G polymorphism was associated with persistent hyperglycaemia at 5 years (p=0.001). Haplotypes formed by the addition of other SNPs, as haplotype blocks or pairs, did not confer greater association than T45G alone. On logistic regression analysis, T45G independently predicted persistent hyperglycaemia at 5 years (OR=2.25, 95% CI 1.29-3.95, G carriers vs TT; p=0.005). It also predicted persistent hyperglycaemia in a nested case-control study involving 158 sex- and age-matched controls with persistent NGT (p=0.012, adjusted for BMI), and that of diabetes or glycaemia progression (p<0.05) in a meta-analysis that also included two published studies in Europid subjects. CONCLUSIONS/INTERPRETATION: Our findings support a significant role of this common ADIPOQ gene polymorphism in predicting glycaemic status in southern Chinese people.

Adiponectin↗
PubMed2006

Adrenomedullin--a potential disease activity marker and suppressor of nephritis activity in systemic lupus erythematosus.

OBJECTIVES: To investigate whether plasma adrenomedullin (AM) level is elevated in lupus nephritis and to examine if plasma AM level is correlated with systemic lupus erythematosus (SLE) disease activity and severity of lupus nephritis after multivariate adjustment. METHODS: Consecutive SLE patients and healthy volunteers of age >/=16 were recruited from the rheumatology clinics of two hospitals in Hong Kong. SLE patients with nephritis fulfilled the American College of Rheumatology criteria for renal involvement and had percutaneous renal biopsy performed. Subjects were divided into three groups: (i) SLE patients with nephritis, (ii) SLE patients without nephritis and (iii) normal controls. The demographic and clinical variables were compared between these groups of patients and plasma AM level was determined by radioimmunoassay. Factors associated with plasma AM level were explored by regression analysis with adjustment of confounding factors. RESULTS: Sixty SLE patients (39 with nephritis and 21 without) and 23 normal subjects were studied. The plasma AM level of SLE patients was significantly higher than that of normal controls. SLE patients with nephritis had significantly higher plasma AM level than those without nephritis and normal controls (P<0.001). In regression analysis, proteinuria was negatively associated with plasma AM level (P=0.006) whereas SLE disease activity index was positively associated with plasma AM level after multivariate adjustment (P=0.002). CONCLUSIONS: Plasma AM is elevated in lupus nephritis, which correlates with lupus disease activity. It is negatively associated with urine protein excretion although it is unrelated to the type of renal pathology per se. Plasma AM may play a role to suppress the activity of lupus nephritis.

Adrenomedullin↗
PubMed2006

Meta-analysis of large outcome trials of angiotensin receptor blockers in hypertension.

Angiotensin receptor blockers (ARBs), also known as sartans, block the activation of angiotensin type 1 receptors and have a recognised role in the treatment of heart failure and nephropathy. Since 2002, there have been three major outcome trials of ARBs in hypertension. We performed a meta-analysis to evaluate the impact of ARB on major outcomes. Randomised controlled trials of ARBs in hypertensive subjects with an average follow-up of at least 2 years and at least 100 major cardiovascular events were included. For each trial, the ARB used, number and characteristics of subjects, baseline and change in blood pressure, cardiovascular and noncardiovascular outcomes were recorded. Three trials involving 29 375 subjects were included in the meta-analysis. In Losartan Intervention For Endpoint (LIFE) and Study on Cognition and Prognosis in the Elderly (SCOPE) but not in Valsartan Antihypertensive Long-term Use Evaluation trial (VALUE), an ARB reduced the occurrence of the primary end point and stroke compared to control. Compared to other antihypertensive drugs, ARB treatment was associated with no significant change in all-cause mortality (relative risk ratio (RRR) 0.96, 95% CI: 0.88-1.06, P = 0.45). There was an increase in myocardial infarction (RRR, 1.12, 95% CI: 1.01-1.26, P = 0.041), but a decrease in new-onset diabetes mellitus (RRR, 0.80, 95% CI: 0.74-0.86, P < 0.0000001). In conclusion, the reduction in new-onset diabetes partly offsets any increase in the risk of myocardial infarction. Most hypertensive patients require more than one class of drugs. Small differences in treatment outcome should not over-ride the importance of good blood pressure control.

Aged↗
PubMed2006

Association of hypertension with single nucleotide polymorphisms in the quantitative trait locus for abdominal obesity-metabolic syndrome on chromosome 17.

Genome scan in Chinese revealed an association of blood pressure with the microsatellite marker D17S1303, which lies in a quantitative trait locus for the abdominal obesity-metabolic syndrome (AOMS2) at 17p12 on chromosome 17. We previously reported that D17S1303 was associated with hypertension and obesity. Therefore, we studied 10 single nucleotide polymorphisms (SNP) within 3 kb of D17S1303. One hundred and eighty hypertensive subjects (91 men, 89 women, age 53+/-12 years) and 180 normotensive matched controls (91 men, 89 women, age 52+/-11) were genotyped using the Sequenom genotyping platform. Allelic frequencies in these Chinese subjects differed from those reported for Caucasians. Three SNPs (rs11656507, rs1357926, rs852319) were homozygous in our subjects. The genotype frequencies of rs852320, rs852321 and rs852322 did not differ between hypertensive and normotensive subjects. However, there were significant differences for rs1525402 (P=0.048), rs2692343 (P=0.022), rs2692344 (P=0.017) and rs2321313 (P=0.028). A four-locus haplotype comprising G at rs1525402, C at rs2692343, C at rs2692344 and G at rs2321313 was associated with lower systolic blood pressure (P=0.023) and normotension (P=0.048). Our results provide further evidence that there is a gene, as yet unidentified, influencing blood pressure in the vicinity of D17S1303 in a quantitative trait locus for abdominal obesity-metabolic syndrome at 17p12.

Chi-Square Distribution↗
PubMed2005

Fatal interaction between clarithromycin and colchicine in patients with renal insufficiency: a retrospective study.

BACKGROUND: Clarithromycin is frequently used to treat community-acquired pneumonia in elderly persons. Like erythromycin, it may interact with other drugs by interfering with metabolism by cytochrome P450 enzymes and with the P-glycoprotein transporter system. Colchicine, used for treatment of acute gout and for prophylaxis, may cause bone marrow toxicity. It is metabolized by CYP3A4 and is transported by P-glycoprotein. Initial case reports suggested potentially fatal interactions between clarithromycin and colchicine. METHODS: A retrospective study was conducted with 116 patients who were prescribed clarithromycin and colchicine during the same clinical admission. Case-control comparisons were made between patients who received concomitant therapy with the 2 drugs and patients who received sequential therapy. We assessed the clinical presentations and outcomes of the 2 patient groups and analyzed the risk factors associated with fatal outcomes. RESULTS: Nine (10.2%) of the 88 patients who received the 2 drugs concomitantly died. Only 1 (3.6%) of the 28 patients who received the drugs sequentially died. Multivariate analysis of the 88 patients who received concomitant therapy showed that longer overlapped therapy (relative risk [RR], 2.16; 95% confidence interval [CI], 1.41-3.31; P< or =.01), the presence of baseline renal impairment (RR, 9.1; 95% CI, 1.75-47.06; P<.001), and the development of pancytopenia (RR, 23.4; 95% CI, 4.48-122.7; P<.001) were independently associated with death. CONCLUSIONS: Clarithromycin increases the risk of fatal colchicine toxicity, especially for patients with renal insufficiency. Since there are other drugs for treatment of pneumonia and gout, these 2 drugs should not be coprescribed, because of the risk of fatality.

Aged↗
PubMed2005

Association of essential hypertension with a microsatellite marker on chromosome 17.

Hypertension is related to sodium intake, and many patients with essential hypertension are overweight and have the metabolic syndrome. We therefore studied microsatellite markers close to the thiazide-sensitive Na-Cl cotransporter on chromosome 16 and a quantitative trait locus for abdominal obesity-metabolic syndrome (AOMS2) on chromosome 17, which have been found to be linked to hypertension in a previous genome scan in Chinese. There were 84 hypertensive subjects (44 men, 40 women, age 53+/-13 years) and 88 normotensive controls (40 men, 48 women, age 54+/-13 years) recruited. Specific oligonucleotide primers were used to amplify genomic DNA spanning the microsatellite markers D16S3396 and D17S1303 that consist of ATA and GATA repeats, respectively. We did not find any association between D16S3396 and blood pressure. In contrast, the distribution of D17S1303 genotypes differed between hypertensive subjects and normal controls (P = 0.014). The number of GATA repeats correlated inversely with diastolic blood pressure (r = -0.18, P = 0.02) and body mass index (r = -0.12, P = 0.01). Nine GATA repeats in D17S1303 were associated with hypertension (OR 2.19, 95% CI 1.08-4.44, P = 0.027), while 14 GATA repeats were associated with normotension (OR 0.26, 95% CI 0.10-0.66, P = 0.002). The diastolic blood pressure in those with or without the (GATA)9 allele was 85.9+/-13.6 and 79.2+/-13.6 mmHg respectively (P = 0.01), and in those with or without the (GATA)14 allele it was 73.8+/-11.0 and 81.8+/-14.0 mmHg respectively (P = 0.003). Our results provide further evidence that a gene predisposing to hypertension in Chinese is in the vicinity of the microsatellite D17S1303.

Alleles↗
PubMed2005

Randomised controlled trial of qigong in the treatment of mild essential hypertension.

Exercise and relaxation decrease blood pressure. Qigong is a traditional Chinese exercise consisting of breathing and gentle movements. We conducted a randomised controlled trial to study the effect of Guolin qigong on blood pressure. In all, 88 patients with mild essential hypertension were recruited from the community and randomised to Goulin qigong or conventional exercise for 16 weeks. The main outcome measurements were blood pressure, health status (SF-36 scores), Beck Anxiety and Depression Inventory scores. In the qigong group, blood pressure decreased significantly from 146.3+/-7.8/93.0+/-4.1 mmHg at baseline to 135.5+/-10.0/87.1+/-7.7 mmHg at week 16. In the exercise group, blood pressure also decreased significantly from 140.9+/-10.9/93.1+/-3.5 mmHg to 129.7+/-11.1/86.0+/-7.0 mmHg. Heart rate, weight, BMI, waist circumference, total cholesterol, renin and 24 h urinary albumin excretion significantly decreased in both groups after 16 weeks. General health, bodily pain, social functioning and depression also improved in both groups. No significant differences between qigong and conventional exercise were found. In conclusion, Guolin qigong and conventional exercise have similar effects on blood pressure in patients with mild hypertension. While no additional benefits were identified, it is nevertheless an alternative to conventional exercise in the nondrug treatment of hypertension.

Aged↗
PubMed2005

Pharmacokinetics of pitavastatin in subjects with Child-Pugh A and B cirrhosis.

AIM: Lipid lowering therapy with 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors is increasingly used for the prevention of cardiovascular events, but they should be used with caution in patients with impaired liver function. We therefore studied the pharmacokinetics of pitavastatin in patients with liver cirrhosis. METHODS: Plasma concentrations of pitavastatin were determined after administration of 2 mg single-dose pitavastatin to 12 male patients with liver cirrhosis (six Child-Pugh grade A and six grade B). These results were compared with the single-dose pharmacokinetic results obtained from six male volunteers without liver disease. RESULTS: Administration of 2 mg single-dose pitavastatin to patients with Child-Pugh grade A and grade B cirrhosis resulted in a 1.19- and 2.47-fold increase in Cmax and 1.27- and 3.64-fold increase in AUCt, respectively, when compared with normal subjects. The geomean Cmax of pitavastatin was 59.5 ng ml(-1), 70.7 ng ml(-1) and 147.1 ng ml(-1) in the control, Child-Pugh grade A and Child-Pugh grade B groups, respectively. The geomean AUCt of pitavastatin in the three groups was 121.2 ng h(-1) ml(-1), 154.2 ng h(-1) ml(-1) and 441.7 ng h(-1) ml(-1), respectively. The geomean Cmax of pitavastatin lactone was 20.3 ng ml(-1), 19.1 ng ml(-1) and 9.9 ng ml(-1) in the control, Child-Pugh grade A and grade B groups, respectively. The AUCt of pitavastatin lactone was 120.2 h(-1) ml(-1), 108.8 h(-1) ml(-1) and 87.5 h(-1) ml(-1), respectively. CONCLUSION: The plasma concentration of pitavastatin is increased in patients with liver cirrhosis. In such patients, caution is required, although dose reduction may not be necessary in Child-Pugh A cirrhosis.

Adult↗
PubMed2005

Queen Mary Utilization of Antihypertensive Drugs Study: side-effects of antihypertensive drugs.

BACKGROUND AND OBJECTIVE: Effective prevention of cardiovascular events in hypertensive patients requires good control of blood pressure. Side-effects of antihypertensive drugs affect tolerability and compliance. Accordingly, we surveyed side-effects in the hypertension outpatient clinic. METHODS: A total of 228 patients (109 men, 119 women) were interviewed in April-May 2004 in the Queen Mary Utilization of Antihypertensive Drugs Study. RESULTS: The percentage of patients receiving no drug (life-style modification), one, two, three and over three drugs were 3, 30, 40, 22 and 6% respectively. The proportion of patients taking calcium channel blockers, beta-blockers (BB), angiotensin-converting enzyme inhibitors, thiazide diuretics, alpha-blockers and angiotensin receptor blockers were 65, 64, 33, 24, 4 and 7% respectively. Blood pressure on treatment was 144+/-21/82+/-11 mmHg. Among patients on antihypertensive drug therapy, 34% reported adverse effects: dizziness (9%), ankle swelling (7%), headache (5%), fatigue (4%), chest discomfort (3%) and cough (3%). Fewer patients on BBs reported side-effects (OR 0.46, P=0.008). The likelihood of experiencing side-effects was unrelated to sex, age, weight, BMI, years of treatment, number of drugs used, heart rate on treatment or compliance. CONCLUSIONS: To achieve good blood pressure control, multiple drugs are used. Thiazides are underused whereas BBs are popular. The popularity of the latter may be related to its tolerability.

Adult↗
PubMed2004

Chloramphenicol succinate, a competitive substrate and inhibitor of succinate dehydrogenase: possible reason for its toxicity.

From our previous study [Eur. J. Clin. Pharmacol. 56 (2000) 405] we hypothesized that chloramphenicol succinate (CAPS) may be a competitive substrate for succinate dehydrogenase (SDH). It may be oxidized by SDH to release chloramphenicol (CAP), which may inhibit SDH by feed back mechanism. The present ex-vivo/in vitro study was aimed to investigate this possibility by using human tissues (bone marrow and liver samples) and animal tissues (rat liver and kidney). The effect of different SDH activators and specific inhibitors was studied on CAPS metabolism by SDH. The metabolites and reduction products were detected by using HPLC. In marrow samples, CAPS was slowly oxidized to form CAP. The formation of CAP (oxidation product) was enhanced by FAD and low malonate and inhibited by high malonate and 3-NPA. Similar results were obtained with mitochondria from human and rat tissues. These studies suggest that CAPS could be a competitive oxidative substrate and the metabolite CAP could be an inhibitor at the reduction site. Therefore, SDH could be a target molecule responsible for CAPS induced toxicity.

Animals↗
PubMed2004

Long-term combination therapy with aspirin and clopidogrel.

The possible additive antiplatelet effects of aspirin and clopidogrel have been explored in the Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) and Management of Atherothrombosis with Clopidogrel in High Risk Patients (MATCH) studies. To assess the overall absolute beneficial and/or harmful impact of aspirin and clopidogrel combination therapy compared with monotherapy with either drug, we analyzed the results from both trials in terms of number needed to treat per year. Treating between 35 and 204 at-risk patients for 1 year with combination therapy appeared to prevent 1 patient from experiencing an adverse primary cardiovascular outcome; whereas, about 1 in 63 such patients appeared liable to major bleeding during that period. We determined that the evidence to date indicates no overall advantage for combination therapy with anti-platelet drugs in preference to monotherapy.

Angina, Unstable↗
PubMed2004

Increased adrenomedullin expression in lungs in endotoxaemia.

Adrenomedullin (AM) is a peptide involved in cardiovascular homeostasis and in inflammation. We examined its expression in a rat model of endotoxaemia. Male Sprague-Dawley rats received intraperitoneal injection of 5 or 10 mg/kg lipopolysaccharide (LPS), or saline as control. Rats were killed at 1, 3, 6, 12 and 24 h after injection. LPS at 5 mg/kg, but not saline, increased plasma AM significantly at 3 h. At 10 mg/kg, plasma AM was raised at 3, 6 and 12 h. Immunoreactive AM concentration in lung increased after 5 or 10 mg/kg LPS, but not saline. PreproAM mRNA level in lung was significantly increased at 3 and 6 h. In conclusion, endotoxin stimulates the expression of AM in the lungs and increases its circulatory concentration. AM may be involved in the systemic response to sepsis.

Adrenomedullin↗
PubMed2003

Knowledge of cardiopulmonary resuscitation among the public in Hong Kong: telephone questionnaire survey.

OBJECTIVES: To evaluate the knowledge of basic life-support and training experience in cardiopulmonary resuscitation among the public in Hong Kong and to identify areas for improvement in public education. DESIGN: Telephone interview using a structured multiple-choice questionnaire. SETTING: Random cross-section of the Hong Kong public, from mid-March to May 2002. PARTICIPANTS: Men and women aged 16 years and older selected using random telephone dialling. MAIN OUTCOME MEASURE: Overall score in the cardiopulmonary resuscitation knowledge questionnaire. RESULTS: Of the 357 participants, approximately 12% had received cardiopulmonary resuscitation training. Cardiopulmonary resuscitation knowledge in Hong Kong was poor, even among the previously trained and especially with regard to circulatory maintenance. The most common reason for not taking cardiopulmonary resuscitation training was lack of time. CONCLUSION: The degree of citizen preparedness in initiating cardiopulmonary resuscitation is very poor in Hong Kong. Intensified educational efforts and exploration of new approaches to improve this first stage in the chain of survival are warranted.

Adolescent↗
PubMed2002

Blockade of the renin-angiotensin system.

The renin-angiotensin-aldosterone system plays a key role in the regulation of fluid and electrolyte balance. Angiotensin-converting enzyme inhibitors inhibit angiotensin-converting enzyme and have been shown to be effective in many cardiovascular diseases. They should be considered for the treatment of hypertension in patients with heart failure, previous myocardial infarction, diabetes, or proteinuria. There are a number of side-effects associated with angiotensin-converting enzyme inhibitors, especially persistent dry cough. Angiotensin II receptor antagonists (sartans) provide a more specific blockade of the renin-angiotensin-aldosterone system and are associated with fewer side-effects, including cough. Their long-term efficacy and tolerability in the treatment of patients with hypertension has, however, yet to be established. Periodic monitoring of renal function and electrolytes is required in patients treated with an angiotensin-converting enzyme inhibitor or a sartan.

Angiotensin II↗