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Biomedical subjects

K S Woo

Publications and source records attributed to K S Woo.

At least 19 recordsLinked to original sources
PubMed2006

Mannheim carotid intima-media thickness consensus (2004-2006). An update on behalf of the Advisory Board of the 3rd and 4th Watching the Risk Symposium, 13th and 15th European Stroke Conferences, Mannheim, Germany, 2004, and Brussels, Belgium, 2006.

Intima-media thickness (IMT) is increasingly used as a surrogate end point of vascular outcomes in clinical trials aimed at determining the success of interventions that lower risk factors for atherosclerosis and associated diseases (stroke, myocardial infarction and peripheral artery diseases). The necessity to promote further criteria to distinguish early atherosclerotic plaque formation from thickening of IMT and to standardize IMT measurements is expressed through this updated consensus. Plaque is defined as a focal structure that encroaches into the arterial lumen of at least 0.5 mm or 50% of the surrounding IMT value or demonstrates a thickness >1.5 mm as measured from the media-adventitia interface to the intima-lumen interface. Standard use of IMT measurements is based on physics, technical and disease-related principles as well as agreements on how to perform, interpret and document study results. Harmonization of carotid image acquisition and analysis is needed for the comparison of the IMT results obtained from epidemiological and interventional studies around the world. The consensus concludes that there is no need to 'treat IMT values' nor to monitor IMT values in individual patients apart from exceptions named, which emphasize that inside randomized clinical trials should be performed. Although IMT has been suggested to represent an important risk marker, according to the current evidence it does not fulfill the characteristics of an accepted risk factor. Standardized methods recommended in this consensus statement will foster homogenous data collection and analysis. This will help to improve the power of randomized clinical trials incorporating IMT measurements and to facilitate the merging of large databases for meta-analyses.

Adult↗
PubMed2006

Plasma beta-globin DNA as a prognostic marker in chest pain patients.

BACKGROUND: Acute coronary syndrome may involve cell death and the release of nucleic acids into the circulation. We thus investigated whether plasma DNA concentrations are increased and determined its prognostic significance in patients with ACS. METHODS: Real-time polymerase chain reaction was used to quantitatively measure the beta-globin gene from blood samples taken from patients presenting to an emergency department with chest pain of probable cardiac cause. RESULTS: Samples from 58 patients with chest pain, and from 21 age- and sex-matched healthy control subjects were analysed. Compared with the control group, median plasma DNA concentrations were increased 1.5-fold in patients with minor cardiac injury, were increased further in patients with STEA and STEMI, and were the highest in those patients who died within 2 years (P=0.0005; post-hoc Dunn's, P<0.05). Median plasma DNA concentrations were higher in patients who later developed heart failure (1060 vs. 500 kGE/l; P=0.0095); higher in patients who later reinfarcted (1000 vs. 530 kGE/l; P=0.0298); higher in patients who had a cardiac arrest in that admission (1350 vs. 525 kGE/l; P=0.04); and were higher in patients who were readmitted within 6 months of discharge (725 vs. 475 kGE/l; P=0.04). CONCLUSION: Plasma DNA is a potential marker for post-ACS complications.

Adult↗
PubMed2006

Factors associated with healthcare utilization costs for statin therapy--a pilot study in Hong Kong.

BACKGROUND: Socio-economic status, comorbidities and adherence to statin therapy might affect the cost-effectiveness of statin therapy in hyperlipidemia. OBJECTIVE: To examine the effects size of demographic factors, clinical factors and adherence to statin therapy on the direct medical costs for Chinese patients at high risk of coronary heart disease (CHD). METHODS: This was a prospective, observational cohort study conducted in the outpatient departments of a public teaching hospital in Hong Kong. Patients at high risk of CHD who had been on statin monotherapy for < 12 months were recruited. Baseline demographic and clinical data were obtained. Statin adherence was monitored prospectively over 6 months using the Medication Event Monitoring System. Total direct medical costs per member per month (cPMPM), including cost for clinic visits, statin medication, laboratory tests on lipids and management of CHD events if any, were calculated from the perspective of a public healthcare organization. RESULTS: 83 patients completed the study. Median cPMPM in 80 patients (96% of 83 patients) without a new CHD event (USD 42) and for 3 (4%) patients who experienced CHD events (USD 444) were significantly different (p = 0.003). History of congestive heart failure (beta = 1,957, 95% CI = 1,006 - 2,909), male gender (beta = 584, 95% CI = 215 - 952), coronary atherosclerosis (beta = 1,436, 95% CI = 538 - 2,334) and diabetes mellitus (beta = 604, 95% CI = 136 - 1,07 1) were positive predictors for cPMPM. CONCLUSION: In this pilot study male gender, diabetes mellitus, congestive heart failure and coronary atherosclerosis appear to be significantly associated with higher costs for Chinese patients at high risk of CHD.

Cohort Studies↗
PubMed2006

Antecedent risk factors and their control in young patients with a first myocardial infarction.

INTRODUCTION: Identifying and controlling cardiovascular risk factors at an early age may prevent cases of young myocardial infarction (MI). We studied age-related differences in the cumulative incidence of risk factors and the adequacy of primary prevention by surveying 1,556 patients with a first MI admitted to a tertiary hospital in Singapore. METHODS: This is a single centre registry-based study on patients admitted with a first MI to a tertiary hospital in Singapore. We stratified the cohort into younger (45 years of age and younger) and older (older than 45 years of age) groups. The presence of five risk factors, namely: hypertension, diabetes mellitus (DM), smoking, a family history of premature MI, and hyperlipidaemia, was assessed at the point of care by interview and prior medical records when obtainable. We also determined by the same methods, if these patients were receiving active treatment for DM, hypertension or hyperlipidaemia prior to their first MI. Lipid levels were measured within 24 hours of admission. RESULTS: 96 percent of patients 45 years and younger and 92 percent of those older than 45 years had at least one antecedent risk factor. The 45 years and younger age group had a higher incidence of untreated hypertension (odds ratio 2.99, 95 percent confidence interval 2.00-4.46, p-value is less than 0.001) and hyperlipidaemia (odds ratio 1.71, 95 percent confidence interval 1.20 - 2.43, p-value is equal to 0.002). CONCLUSION: A majority of young patients with a first MI have at least one identifiable antecedent risk factor. There is significant undertreatment of hypertension and hyperlipidaemia in this age group.

Adult↗
PubMed2005

Method of measuring charge distribution of nanosized aerosols.

In this paper, we present the development of a method to accurately measure the positive and negative charge distribution of nanosized aerosols using a tandem differential mobility analyzer (TDMA) system. From the series of TDMA measurements, the charge fraction of nanosized aerosol particles was obtained as a function of equivalent mobility particle diameter ranging from 50 to 200 nm. The capability of this new approach was implemented by sampling from a laminar diffusion flame which provides a source of highly charged particles due to naturally occurring flame ionization process. The results from the TDMA measurement provide the charge distribution of nanosized aerosols which we found to be in reasonable agreement with Boltzmann equilibrium charge distribution theory and a theory based upon charge population balance equation (PBE) combined with Fuchs theory (N.A. Fuchs, Geofis. Pura Appl. 56 (1963) 185). The theoretically estimated charge distribution of aerosol particles based on the PBE provides insight into the charging processes of nanosized aerosols surrounded by bipolar ions and electrons, and agree well with the TDMA results.

Journal Article↗
PubMed2004

Mannheim intima-media thickness consensus.

Intima-media thickness (IMT) is increasingly used in clinical trials as a surrogate end point for determining the success of interventions that lower risk factors for atherosclerosis. The necessity for unified criteria to distinguish early atherosclerotic plaque formation from thickening of IMT and to standardize IMT measurements is addressed in this consensus statement. Plaque is defined as a focal structure that encroaches into the arterial lumen of at least 0.5 mm or 50% of the surrounding IMT value or demonstrates a thickness of > or =1.5 mm as measured from the media-adventitia interface to the intima-lumen interface. Standard use of IMT measurements is recommended in all epidemiological and interventional trials dealing with vascular diseases to improve characterization of the population investigated. The consensus concludes that there is no need to 'treat IMT values' nor to monitor IMT values in individual patients apart from few exceptions. Although IMT has been suggested to represent an important risk marker, it does not fulfill the characteristics of an accepted risk factor. Standardized methods recommended in this consensus statement will foster homogenous data collection and analysis. This will help to improve the power of studies incorporating IMT measurements and to facilitate the merging of large databases for meta-analyses.

Arteriosclerosis↗
PubMed2004

Inhibitory effects of budesonide, desloratadine and dexamethasone on cytokine release from human mast cell line (HMC-1).

OBJECTIVE: To determine the inhibitory potency of budesonide on interleukin (IL)-4, 6 and 8, GM-CSF and TNF-alpha release from the human mast cell line (HMC-1) in comparison with the systemic glucocorticosteroid, dexamethasone, and H(1) antagonist, desloratadine. METHODS: HMC-1 was stimulated with 25 ng/ml phorbol 12- myristate 13-acetate (PMA) and 2.5 x 10(-7) M ionomycin (A23187) for 6, 12 and 24 h in both the presence and absence of 10(-6)-10(-10) M concentrations of the test drugs. Culture supernatants were collected and assayed by ELISAs. RESULTS: HMC-1 produced substantial amounts of GM-CSF and IL-8 and smaller amounts of TNF-alpha, IL-4 and IL-6 after being stimulated with PMA together with A23187. Budesonide and dexamethasone had potent inhibitory effects and desloratadine had modest inhibitory effects on the release of these cytokines. Budesonide was more potent than dexamethasone at most concentrations and time points. IL-4 was the cytokine which was most susceptible to inhibition by the three tested drugs. The inhibitory effects, in some cases, were time- and concentration-dependent. CONCLUSION: Budesonide had a potent inhibitory effect on cytokine release from HMC-1. Its potency was greater than that of both dexamethasone and desloratadine.

Budesonide↗
PubMed2004

Overweight in children is associated with arterial endothelial dysfunction and intima-media thickening.

OBJECTIVE: We sought to study arterial endothelial function and carotid intima-media thickness (IMT), both early markers of atherosclerosis, in overweight compared to normal children. DESIGN: Case-control comparison. SUBJECTS: A total of 36 asymptomatic overweight children (body mass index (BMI)>23; mean 25+/-3) aged 9-12 y and 36 age- and gender-matched nonobese healthy children (BMI<21) from a school community. MEASUREMENTS: The key parameters were: BMI, arterial endothelial function (ultrasound-derived endothelium-dependent dilation) and carotid artery IMT. The secondary parameters measured included body fat content, waist-hip ratio (WHR), blood pressures, blood lipids, insulin and glucose. RESULTS: The two groups were well matched for blood pressures, cholesterol and glucose levels, but BMI (P<0.0001), body fat (P=0.001), WHR (P<0.05), fasting blood insulin (P=0.001) and triglyceride levels (P<0.05) were higher in obese children. Overweight was associated with impaired arterial endothelial function (6.6+/-2.3 vs 9.7+/-3.0%, P<0.0001) and increased carotid IMT (0.49+/-0.04 mm vs 0.45+/-0.04 mm, P=0.006). The degree of endothelial dysfunction correlated with BMI (P<0.003) on multivariate analysis. CONCLUSION: Obesity, even of mild-to-moderate degree, is independently associated with abnormal arterial function and structure in otherwise healthy young children.

Anthropometry↗
PubMed2002

Carotid intima-media thickness in patients with head and neck irradiation for the treatment of nasopharyngeal carcinoma.

AIM: Intima-media thickness (IMT) has been shown to be useful in the evaluation and monitoring of carotid artery atherosclerosis in patients at risk of cardiovascular events. In this study, we aimed to examine the IMT in patients with nasopharyngeal carcinoma (NPC) who received irradiation to the carotid arteries during radiotherapy, and compared them with a control group. MATERIALS AND METHODS: Fifty-one NPC patients (aged between 39 and 69 years) and a group of 51 age-and sex-matched controls were studied by ultrasound. The IMT at the far wall of the common carotid artery was measured three times and the average value taken in each subject. The IMT of both groups were compared. Risk factors for IMT thickness, including hypertension, smoking, hyperglycaemia, hypercholesterolaemia, history of cerebrovascular accidents and cardiovascular disease, were also studied. RESULTS: The mean carotid IMT of patients in the NPC group (2.2+/-1.5 mm) was statistically greater than that in normal controls (0.7+/-0.15 mm) (P < 0.05). There was no statistically significant difference between the IMT in the right and left common carotid arteries within each group of patients. CONCLUSION: The findings suggest that patients with irradiation have increased arterial IMT. As they are asymptomatic the clinical relevance is not clear.

Carotid Artery, Common↗
PubMed2002

Effects of dietary intervention and strength training on blood lipid level in obese children.

AIMS: To evaluate effects of a low energy diet, with or without strength training, on blood lipid profile in obese children. METHODS: Eighty two obese children were enrolled into a six week dietary programme, and were randomly allocated to a training group or a non-training group. The training group underwent regular exercise sessions with emphasis on strength training. RESULTS: Height increased significantly, with a non-significant reduction in body mass index. Fat free mass increased significantly in the training group. Serum total cholesterol was significantly reduced in both groups. The LDL:HDL ratio significantly decreased in the training group. CONCLUSION: Results support the potentially beneficial effects of both diet and physical training. Further and longer term evaluation of such programmes is required.

Adult↗
PubMed2001

The Mediterranean score of dietary habits in Chinese populations in four different geographical areas.

OBJECTIVE: To compare the dietary intake of Chinese people living in Pan Yu, Hong Kong, San Francisco and Sydney with respect to cardiovascular health, using the Mediterranean diet score, examining the effects of age, gender, urbanization and acculturation on the diet score. SUBJECTS: A total of 500 men and 510 women in Hong Kong were recruited as a territory-wide stratified random sample. Subjects were recruited in response to local advertisements for the other three sites: Pan Yu, 58 men, 95 women; San Francisco, 166 men, 192 women; Sydney, 95 men, 73 women. METHOD: Food-frequency questionnaire over a 7 week period. A high/healthy score was taken as > or =4 for men and >3 for women, representing a dietary pattern beneficial for cardiovascular health. RESULTS: In Hong Kong, more women in the middle age group (35-54) had a high score than other age groups, and overall more women had high scores than men. In comparing the four geographical regions, Pan Yu had the highest number of subjects with high score, and Hong Kong had the lowest. With the exception of the younger population and men in Hong Kong, the percentage of the population with a high score in all sites is greater than among elderly Greeks consuming a more traditional heart-healthy Mediterranean diet. CONCLUSION: Considerable variations in Chinese dietary patterns exist with respect to age, gender and geographic location. Overall, the Chinese diet is comparable to the Mediterranean diet and may be expected to have similar health benefits that have been documented for the traditional Mediterranean diet.

Adult↗
PubMed2001

Correlation between Helicobacter pylori infection, gastric inflammation and serum homocysteine concentration.

BACKGROUND: Epidemiological studies have suggested a link between chronic Helicobacter pylori infection and ischemic heart disease but the underlying mechanism remains elusive. We hypothesized that H. pylori-associated chronic gastritis causes impairment of absorption of vitamin cofactors that are essential in the metabolism of homocysteine and results in hyperhomocysteinemia. MATERIALS AND METHODS: Forty-nine dyspeptic patients were studied. H. pylori infection was defined by rapid urease test and histology. Fasting serum homocysteine level, which was measured by a validated commercial fluorescence polarization immunoassay, was correlated with H. pylori infection statuses and gastric histology. H. pylori-infected patients were followed up for 24 weeks post eradication for changes in serum homocysteine concentration. RESULTS: Univariate analyses showed that serum homocysteine level correlated with increasing age (p <.001), male sex (p =.003) and smoking habit (p =.025). There was no significant difference in serum homocysteine levels between H. pylori infected and uninfected subjects (median 10.5 vs. 10.2 micromol/l). After successful eradication of the bacterium, there was no significant reduction in homocysteine level. Moreover, there was no correlation between homocysteine level and gastric histology including H. pylori density, activity and inflammation scores, presence of atrophy or intestinal metaplasia. CONCLUSIONS: The postulated link between H. pylori infection and ischemic heart disease, if it actually exists, is unlikely to be mediated through hyperhomocysteinemia.

Adult↗
PubMed2001

Acid stress upregulated outer membrane proteins in clinical isolates of Neisseria gonorrhoeae, but not most commensal Neisseria.

Human immune serum recognition of outer membrane components from commensal and pathogenic Neisseria cultured under neutral and acidic conditions was investigated. Acid stress caused no detectable alterations in lipooligosaccharide migration and (or) staining, in outer membrane protein profiles, or in immune serum recognition of outer membrane components from Neisseria mucosa or Neisseria sicca. There was also no difference in the lipoologosaccharide electrophoretic pattern of acid- and neutral-grown Neisseria lactamica, but there were differences in outer membrane protein expression. The outer membrane protein alterations induced by acid stress in N. lactamica were not the same as those seen in isolates from patients with uncomplicated gonococcal infection, pelvic inflammatory disease, and disseminated gonococcal infection. Many differences were detected in the immune serum recognition of outer membrane components from acid- and neutral-cultured N. lactamica and from the clinical isolates of Neisseria gonorrhoeae, and these should be considered in vaccine design.

Bacterial Outer Membrane Proteins↗
PubMed2000

A comparison of endothelial function in Caucasian and Chinese women before and after the menopause.

OBJECTIVE: Arterial endothelial dysfunction is a key atherogenic event that may be related to oestrogen status. We therefore aimed to compare menopause-related changes in endothelial physiology in Chinese and Caucasian females. METHODS: We studied 40 female subjects; 20 Chinese from a rural region of Southern China (ten premenopausal, aged 20-35 years, and ten postmenopausal, aged 55-66 years), and 20 age-matched Caucasian females from Sydney, Australia. All women had a clinical history, resting blood pressure and fasting lipids measured, and endothelial function assessed. Using high-resolution external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilatation) and after sublingual glyceryl trinitrate (GTW) (an endothelium-independent dilator). RESULTS: There was a significant decline in endothelium-dependent dilatation (EDD) comparing Caucasian females from the premenopausal versus postmenopausal groups (8.4+/-2.7% versus 2.7+/-2.9%; P<0.001). In contrast, there was no significant difference in EDD between pre- and postmenopausal Chinese (9.8+/-3.3% versus 8.3+/-1.7%; P=0.22). On multivariate analysis, postmenopausal status was associated with impaired EDD in Caucasian females (P<0.002) independent of serum cholesterol, blood pressure and vessel size. In contrast, EDD in the Chinese females was not significantly influenced by any of these factors. GTW-induced dilatation was also impaired in the older Caucasian females, a finding explained on multivariate analysis by the increased vessel size in this patient group (P=0.03). CONCLUSION: Menopause is associated with impaired arterial endothelial function in Caucasian but not Chinese women. This suggests possible ethnic differences in menopause-related vascular changes.

Adult↗