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Biomedical subjects

T H Lam

Publications and source records attributed to T H Lam.

At least 109 records · Page 6Linked to original sources
PubMed1997

Mortality attributable to cigarette smoking in China.

CONTEXT: The few published prospective studies of smoking and mortality in China have reported low relative risks, but the durations of follow-up were short. OBJECTIVE: To assess the mortality of ever- and never-smokers in a cohort after 20 years of follow-up. DESIGN, SETTING, AND SUBJECTS: A cohort analytic study in a machinery factory in Xi'an, China, involving 1696 people aged 35 years or older (1124 men and 572 women) examined in May 1976. MAIN OUTCOME MEASURES: All-cause and tobacco-associated mortality. RESULTS: A total of 56% of the men and 12% of the women were ever-smokers at baseline. Through August 31, 1996, 218 persons (173 men and 45 women) had died. The relative risks (95% confidence intervals [CIs]) for ever smoking (after adjusting for age, marital status, occupation, education, diastolic blood pressure, and triglyceride and cholesterol levels) for deaths resulting from all causes, all cancer, and coronary heart disease were, respectively, 2.42 (95% CI, 1.72-3.42), 2.50 (95% CI, 1.41-4.43), and 3.61 (95% CI, 1.35-9.67) in men and 2.32 (95% CI, 1.18-4.56), 1.98 (95% CI, 0.50-7.92), and 4.67 (95% CI, 0.78-27.8) in women. CONCLUSIONS: Previous prospective studies of smoking-related mortality in China tended to underestimate the risks, probably because of short durations of follow-up. We have demonstrated that smoking is a major cause of death in China, and the risks are similar to those seen in the United States and the United Kingdom. Thus, about half of the 300 million smokers in China will eventually die of smoking-related diseases if urgent tobacco-control measures are not instituted to prevent this growing epidemic.

Adult↗
PubMed1997

Plasma total antioxidant capacity in an adult Hong Kong Chinese population.

OBJECTIVES: To examine plasma total antioxidant capacity (TAOC) in a Chinese population with a lower incidence of cardiovascular disease compared with Caucasian populations, in relation to dietary intake, age, sex, and the presence of cardiovascular diseases. DESIGN AND METHODS: As part of a randomized territory-wide survey stratified by sex and 10-year age groups; 728 subjects (367 men, 361 women) were recruited. Dietary intake assessment was by a food frequency questionnaire; plasma TAOC was estimated by the ABTS method. RESULTS: The TAOC values were normally distributed, the mean +/- SD being 1.78 +/- 0.18 mmol/L. The mean value was higher in men compared with women, inspite of a lower dietary intake of vitamins A and C per 1000 kcal in the former. Subjects who consumed water spinach twice or more a week had higher mean levels. No difference in mean levels was observed between those with and without hypertension or cardiovascular disease. CONCLUSION: Measurement of plasma TAOC as a risk factor in epidemiological studies of cardiovascular diseases may have limited use, since TAOC include substances associated with a protective effect as well as increased risk.

Adult↗
PubMed1997

Xestospongins: potent membrane permeable blockers of the inositol 1,4,5-trisphosphate receptor.

Xestospongins (Xe's) A, C, D, araguspongine B, and demethylxestospongin B, a group of macrocyclic bis-1-oxaquinolizidines isolated from the Australian sponge, Xestospongia species, are shown to be potent blockers of IP3-mediated Ca2+ release from endoplasmic reticulum vesicles of rabbit cerebellum. XeC blocks IP3-induced Ca2+ release (IC50 = 358 nM) without interacting with the IP3-binding site, suggesting a mechanism that is independent of the IP3 effector site. Analysis of Pheochromocytoma cells and primary astrocytes loaded with Ca2+-sensitive dye reveals that XeC selectively blocks bradykinin- and carbamylcholine-induced Ca2+ efflux from endoplasmic reticulum stores. Xe's represent a new class of potent, membrane permeable IP3 receptor blockers exhibiting a high selectivity over ryanodine receptors. Xe's are a valuable tool for investigating the structure and function of IP3 receptors and Ca2+ signaling in neuronal and nonneuronal cells.

Alkaloids↗
PubMed1997

Clustering of childhood leukaemia in Hong Kong: association with the childhood peak and common acute lymphoblastic leukaemia and with population mixing.

Incidence data of childhood leukaemia (CL) in Hong Kong (1984-90) have been analysed for evidence of variation between small areas. All cases (n=261) were classified by morphological cell type, with the majority (n=205) being acute lymphoblastic leukaemia (ALL), and haematological review has permitted immunophenotypic classification for 73% of these. The data have been examined for evidence of spatial clustering within small census areas (TPUs) and for association with population mixing, with attention focused on those subgroups (especially the childhood peak of ALL--taken here to be diagnoses in children from 24 months up to the seventh birthday--and common ALL) which, it has been hypothesized, may be caused by unusual patterns of exposure and response to common infections. For the whole of Hong Kong, there was evidence of spatial clustering of ALL at ages 0-4 years (P = 0.09) and in the childhood peak (P<0.05). When these analyses were restricted to TPUs where extreme population mixing may have occurred, overall incidence was elevated and significant evidence of clustering was found for ALL (P<0.007) at these ages and for the common ALL in the childhood peak (P = 0.032). Replication of the analyses for subsets of leukaemia that were not dominated by the childhood peak of ALL found no evidence of clustering. This is the first investigation of an association between population mixing and childhood leukaemia in Asia and the first to include clustering and to consider particular subsets. The results are supportive of the 'infectious' aetiology hypothesis for subsets of childhood leukaemia, specifically common ALL in the childhood peak.

Adolescent↗
PubMed1997

Dietary practices and lipid intake in relation to plasma lipid profile in Hong Kong Chinese.

OBJECTIVE: To study dietary lipid intake and plasma lipid profile of the Hong Kong Chinese population as part of a territory wide survey on cardiovascular risk factors. DESIGN: Randomised age and sex stratified survey. SUBJECTS: 1010 subjects aged 25-74 y (500 men, 510 women). MEASUREMENTS: A food frequency method with food tables compiled for Hong Kong was used for nutrient quantitation, while a separate questionnaire was used to examine dietary practices. Plasma lipid profile was estimated using standard laboratory methods. RESULTS: Total calorie, fat, saturated fatty acid (SFA), poly- and mono-unsaturated fatty acid (PUFA and MUFA), and cholesterol intake were higher in men; however when adjusted for caloric intake no difference was observed. Men had lower intake of PUFA as percentage of total energy had a higher Hegsted Score compared with women. Subjects consuming beans twice or more per week had lower total cholesterol and LDL-cholesterol concentrations. Overall, the population dietary intake was close to the ideal for cardiovascular health: percentage fat not greater than 30% of the total calorie intake, saturated fat intake not greater than 10% of calories, and cholesterol less than 180 mg/1000 Kcal. CONCLUSION: The dietary pattern for Hong Kong Chinese appear to be satisfactory with respect to cardiovascular health.

Adult↗
PubMed1997

Predicting stress in first year medical students: a longitudinal study.

While there is ample documentation that medical training is stressful, less is known about predictive variables that might identify students who have the most difficulty in managing stress during medical training. Depression and anxiety in first year medical students were investigated in a longitudinal design. One-hundred and twenty-one medical students (81% of the class) were surveyed. The first survey took place immediately prior to the beginning of medical training (wave 1); the second survey was approximately 8 months after the beginning of classes (wave 2). Medical students who began their first year with relatively low 'A' level grades, high ratings of state anxiety and depression, high trait anxiety and low dispositional optimism, and reliance on avoidant coping strategies were found to be at higher risk for developing depression and anxiety symptoms at wave 2. Students reported increased concern about curriculum and environment, personal competence and endurance, and time to have a life outside medical school at wave 2, compared to their reports at wave 1. Increase in concerns correlated with an increase in depression and anxiety. At both surveys, use of avoidant coping strategies resulted in increased depression and anxiety; at wave 2, active coping and positive reinterpretation resulted in decreased depression and anxiety. These findings suggest characteristics of vulnerable students who might be identified early in their first year and provided with additional support. Educating students to expect an increase in concerns about environment and personal ability to manage the academic load might make these concerns less overwhelming. In addition, information about effective coping strategies (i.e. active coping efforts) and ineffective means of dealing with stress (avoidant coping efforts) might be helpful in preventing distress.

Adaptation, Psychological↗
PubMed1997

Passive smoking and coronary heart disease: a brief review.

1. Whether passive smoking or environmental tobacco smoke (ETS) can cause coronary heart disease (CHD) is controversial. We have undertaken a comprehensive review of the epidemiological studies regarding the relationship between ETS and CHD. 2. We searched for all original papers and reviews and calculated pooled odds ratio using the Mantel-Haenszel method. 3. Ten prospective studies, nine case-control studies and one cross-sectional study were found. Almost all studies showed positive associations between ETS and CHD and a few were statistically significant, with dose-response relationships being evident. Six review papers calculated pooled estimates of the relative risks, which ranged from 1.23 to 1.51. Other studies also showed that ETS could have other cardiovascular effects. 4. The association observed is likely to be real. The criteria for causation of time sequence, consistency, coherence and biological plausibility are satisfied. We conclude that ETS may cause CHD, particularly in women who have never smoked.

Case-Control Studies↗
PubMed1997

A comprehensive study of smoking in primary school children in Hong Kong: implications for prevention.

STUDY OBJECTIVE: To identify factors associated with smoking behaviour in primary school children in Hong Kong. DESIGN: A cross sectional survey in which both children and parents completed questionnaires. The main outcome measure was the smoking status of the children; and risk factors (knowledge of and attitude to smoking and demographic and socioeconomic background) were identified as predictors of ever/never smoking. SETTING AND SUBJECTS: Altogether 9598 primary school children, aged 8-13 years, and attending 27 schools from two districts in Hong Kong participated. MAIN RESULTS: The prevalence of ever-smoking was 12% (1119)-15% (760) in boys and 7% (359) in girls. It ranged from 3% in 8 year old girls to 52% in 13 year old boys. The factors associated with ever-smoking included the following: being a boy (adjusted odds ratio 2.21; 95% confidence interval 1.89, 2.59), increasing age per year (1.48; 1.40, 1.57), living in Kwai Tsing district (1.29; 1.10, 1.50), having one or more smokers at home (2.07; 1.78, 2.39), and having a father who was not working (1.41; 1.19, 1.67). Children who were ever-smokers had both seen and approved of their friends' smoking (8.79; 5.33, 14.50), had a more positive attitude towards smoking (3.35; 2.21, 5.09), and were more successful in recognising cigarette brand names and logos (1.67; 1.42, 1.96), but they lacked confidence (1.78; 1.32, 2.39). CONCLUSIONS: The influences on child smoking are multifactorial and programmes in Hong Kong are falling to curb them. The control of these risk factors must be incorporated in the smoking prevention policy of Hong Kong and supported by future enforced legislation.

Adolescent↗
PubMed1996

The number of stenotic coronary arteries and passive smoking exposure from husband in lifelong non-smoking women in Xi'an, China.

The relationship between the number of stenotic coronary arteries and passive smoking exposure from the husband was examined in a retrospective study of 78 cases with stenotic coronary arteries and 83 controls with normal coronary arteries. All the 161 subjects were examined by coronary arteriography and were Chinese women who had never smoked cigarettes (i.e. lifelong non-smokers). The Pearson's and Spearman's correlation coefficients between the number of stenotic coronary arteries and passive smoking exposure indices were 0.27-0.29 and 0.25-0.28 (all with P < 0.01), respectively. The linear prediction equations from multiple regression analysis showed that passive smoking exposure, after adjustment for other major risk factors, was a significant predictive variable for the number of stenotic coronary arteries. The multiple response logistic regression model was used to estimate the odds ratio of stenotic coronary arteries for passive smoking exposure categories. The crude and adjusted odds ratios showed that the number of stenotic arteries increased with the amount of exposure to passive smoking from the husband. These results provide new evidence to support that passive smoking is causally associated with coronary heart disease.

Adult↗
PubMed1996

Bastadin 20 and bastadin O-sulfate esters from Ianthella basta: novel modulators of the Ry1R FKBP12 receptor complex.

New compounds bastadin 20 (9), 15,34-O-disulfatobastadin 7 (10), and 10-O-sulfatobastadin 3 (11) were isolated from Ianthella basta collected in Exmouth Gulf, Western Australia. Compounds 10 and 11 exhibited moderate differential activity as SR Ca2+ channel agonists (EC50 13.6 and 100 microM, respectively) of the Ry1R FKBP12 complex, while the potency of 9 was almost half that of 10 (EC50 20.6 microM). The problem of dereplication of bastadins was addressed using 1H-NMR "fingerprinting" of MeO signals in the corresponding permethyl bastadin derivatives.

Animals↗
PubMed1996

Effects of an ambient air pollution intervention and environmental tobacco smoke on children's respiratory health in Hong Kong.

BACKGROUND: Two-thirds of complaints received by the Hong Kong Environmental Protection Department in 1988 were related to poor air quality. In July 1990 legislation was implemented to reduce fuel sulphur levels. The objective of this study was to measure the impact of the intervention on respiratory health in primary school children. METHODS: In all, 3521 children, mean age 9.51 years (SD = 0.78), from two districts with good and poor air quality respectively before intervention were followed yearly from 1989 to 1991. Children and parents reported the children's respiratory symptoms using self-completed questionnaires. Factor analysis was used to derive independent scores from 12 symptoms. Four groups of related symptoms were identified and binary variables (presence of any symptom in each group) were treated as dependent variables in modelling using generalized estimating equations procedures. RESULTS: In 1989 and 1990 an excess of respiratory symptoms was observed in the polluted compared with unpolluted district. The significant effects (odds ratio [OR], 95% confidence interval [CI], P value) associated with living in the polluted district were: cough and sore throat (OR = 1.22, 95% CI: 1.04-1.43, P < 0.01) and wheezing (OR = 1.35, 95% CI: 1.10-1.66, P < 0.01). After the intervention, in the polluted district only, sulphur dioxide levels fell by up to 80% and sulphate concentrations in respirable particulates by 38%. Between 1989 and 1990-1991 there was a greater decline in the polluted compared with the unpolluted district for reported symptoms of cough or sore throat, phlegm, and wheezing. The risks to respiratory health for children exposed to tobacco smoke in the home were higher than those for air pollution in both 1989 and 1990 and remained unchanged in 1991. CONCLUSIONS: Air quality can be improved by fuel controls but an effective intersectoral approach is required if other risks from environmental tobacco smoke are to be avoided.

Air Pollution↗
PubMed1996

Smoking and exposure to occupational hazards in 8,304 workers in Guangzhou, China.

This cross-sectional study aimed to describe the pattern of smoking in relation to occupational hazard exposure in a working population in Guangzhou, China. In 1994, data on smoking and occupational hazard exposure from occupational health records of 8,304 subjects aged 35 years or older from 47 randomly selected factories were studied. About 49% of the men and 55% of the women were exposed to dust, chemicals or other hazards. The prevalence of smoking was 56.1% in men and 2.0% in women. The prevalence of smoking in men was higher in those who were younger, with primary education or who were workers. In women, those who were older, with primary education or in management jobs had higher smoking prevalence. In men and women, subjects who were exposed to occupational hazards had higher smoking prevalence: the highest (71.6%) was found in male workers exposed to dust. Urgent tobacco control measures are needed to prevent the epidemic of smoking-related and occupation-related diseases in the workplace in China.

Adult↗
PubMed1996

Knowledge and attitudes about smoking in medical students before and after a tobacco seminar.

A 3-hour seminar on tobacco was introduced to second year (pre-clinical) medical students in Hong Kong in 1994. The differences in knowledge and attitudes were measured by a self-administered and anonymous questionnaire with 14 items before the seminar (n = 145), and again 2 weeks after the seminar (n = 151). The students also completed an evaluation form at the end of the seminar. Before the seminar, the students were most deficient in their knowledge on the exact magnitude of the risks from smoking and on the risks from smoking relative to the risks from air pollution and asbestos. After the seminar, their knowledge increased significantly (P < 0.005). As for attitudes, in the pre-test 35% strongly agreed that tobacco advertising should be completely banned, and 50% did so in the post-test (P = 0.02). The corresponding figures for banning of all forms of tobacco promotion were 26% and 43% (P < 0.005). In the pre-test, one in four students strongly disagreed that doctor's advice to their patients to stop smoking is totally ineffective, with this proportion increasing to 70% in the post-test (P < 0.005). The majority of the students stated that the seminar was useful. The preclinical medical curriculum should, at the very least, include a tobacco seminar. Our survey shows that it is effective in improving students' knowledge and attitudes on tobacco control.

Adult↗
PubMed1996

Patch testing of 490 patients in Hong Kong.

Patch testing, using European standard allergens and suspected causative substances brought in by patients, was carried out in 490 patients with eczema in Hong Kong and 437 completed the test. Before patch testing, 244, 141 and 105 patients were diagnosed as having contact dermatitis, endogenous eczema and unclassified eczema, respectively. After patch testing, the diagnosis of the causal agent was changed in 54 contact dermatitis patients, and 18% of endogenous eczema patients and 34% of unclassified eczema patients were re-diagnosed as contact dermatitis. In the patients with a final diagnosis of contact dermatitis, 19.5% were positive to fragrance mix, followed by nickel sulfate (16.4%) and cobalt chloride (11.3%). The commonest causative agents for contact dermatitis were soap or detergent (22.0%) and traditional Chinese medicine (17.3%); the latter was a more common cause of contact dermatitis than Western medicine (9.0%) or metals (13.4%). The prevalence of allergic reaction to fragrance in Hong Kong was higher than among Chinese in Beijing, Shanghai, Taipei or Singapore (78% ethnic Chinese). Dermatologists should have a high index of suspicion about traditional medications and should patch test with the suspected substance when patients give a history of use.

Dermatitis, Allergic Contact↗
PubMed1996

Motor neuron disease in Hong Kong Chinese: epidemiology and clinical picture.

This study documents the clinical features, incidence and prevalence of motor neuron disease (MND) in Hong Kong Chinese. Patients with MND who were alive between 1989 and 1992 were recruited by retrieval of medical records from the four major hospitals in Hong Kong, and by referral of neurologists, neurosurgeons and medical consultants. Mortality statistics was provided by the Census and Statistics Department. A total of 84 cases were identified with a male preponderance of 1.98:1. The average annual period incidence was 0.31/100,000 and the point prevalence on December 31, 1992, was 0.95/100,000. The mean age at onset was 55.5 years (range 19-81) with a peak observed from 55 to 65 years. The clinical features are similar to other reported series of MND. The incidence and mortality of MND in Hong Kong are therefore lower than the worldwide figures of 2.0/100,000 and 1.5/ 100,000, respectively.

Adult↗
PubMed1995

Stopping drinking and risk of oesophageal cancer.

OBJECTIVE: To examine the effect of stopping drinking on the risk of oesophageal cancer. DESIGN: Hospital based case-control study. SETTING: Surgical departments of four district general hospitals and general practices in Hong Kong. SUBJECTS: Cases were 400 consecutive admissions of patients with histologically confirmed diagnosis of oesophageal cancer during a 21 month period in 1989-90 (87% response rate). Controls were 1598 patients selected from the same surgical departments as the cases and from the general practices from which the cases were originally referred (95% response rate). MAIN OUTCOME MEASURE: Relative risk of developing oesophageal cancer after stopping drinking (adjusted for age, education, place of birth, smoking, and diet). RESULTS: Current light drinking (< 200g ethanol/week) was not associated with significant increase in risk. Among former drinkers risk fell more quickly in moderate (200-599 g/week) than heavy (> or = 600 g/week) drinkers. Even among heavy drinkers, however, risk had dropped substantially after five to nine years of not drinking. The results suggest that the time taken for risk to return to that in subjects who never drink was 10-14 years for moderate drinkers and 15 years or more, if ever, for heavy drinkers. CONCLUSION: Risk of oesophageal cancer decreases fairly rapidly with time after abstaining from drinking. This new finding could be used in health promotion to encourage behavioural changes, especially in heavy drinkers, who have a very high risk of developing oesophageal cancer. It also suggests that alcoholic beverages have a strong effect on the late stage of carcinogenesis.

Adenocarcinoma↗