Biomedical subjects

E Lau

Publications and source records attributed to E Lau.

At least 19 recordsLinked to original sources

PubMed1996

Serum bilirubin and cardiovascular risk factors in a Chinese population.

BACKGROUND: Many risk factors for cardiovascular disease (CVD) have been identified. Recently an association between low concentration of serum bilirubin and increased risk of CVD has been reported. However, information on this topic remains scarce. METHODS: We examined the relationships between serum bilirubin and CVD risk factors in 1508 Hong Kong Chinese. We divided the subjects into four quartiles based on serum bilirubin concentrations. Cardiovascular risk factors studied include age, sex, smoking, obesity glycaemic status and lipid indices. RESULTS: Decreasing serum bilirubin concentration was associated with older age, increased prevalence of smoking, higher body mass index and systolic blood pressure, increased glycated haemoglobin, fasting and 2 h insulin, triglyceride, very-low-density lipoprotein and apolipoprotein B concentrations, and lower high-density lipoprotein concentration. Women had lower bilirubin concentrations than men. After adjustment for age, sex, smoking and insulin levels as covariates, the associations between serum bilirubin concentration and glycated haemoglobin, triglyceride, high-density lipoprotein and very-low-density lipoprotein persisted. The prevalence rates of abnormal glucose tolerance (impaired glucose tolerance or diabetes) were similar amongst the four quartiles of bilirubin concentrations. However, the mean bilirubin concentration was significantly lower in subjects with abnormal glucose tolerance (9.3 +/- 3.5 mumol/l, n = 178) than in normal subjects (10.1 +/- 5.2 mumol/l, n = 1330, P = 0.039). When analysed as a continuous variable by age-adjusted partial correlation coefficients, serum bilirubin concentration was inversely correlated with fasting insulin, triglyceride, very-low-density lipoprotein and glycated haemoglobin level. CONCLUSIONS: There were close associations between low serum bilirubin concentration and increased CVD risk factors. Subjects with abnormal glucose tolerance also had lower serum bilirubin concentration than normal subjects. Some of these associations (body mass index, systolic blood pressure) could be explained by differences in insulin level. These relationships between bilirubin and CVD risk factors require further clarification, although abnormal intermediary metabolism and antioxidant deficiency may be possible linking factors.

Adult↗

PubMed1995

Increased bone resorption and decreased bone formation in Chinese patients with hip fracture.

Biochemical markers of bone formation (bone-specific alkaline phosphatase and osteocalcin) and bone resorption (hydroxyproline excretion and bone isoenzyme of acid phosphatase) were measured in 30 patients (15 M and 15 F) with hip fracture and 30 healthy subjects matched for age and sex. Bone isoenzyme of tartrate-resistant acid phosphatase (TRACP) was measured by a recently developed specific immunoassay. Serum osteocalcin concentration and bone-specific alkaline phosphatase activity were significantly lower and serum TRACP concentration and urinary hydroxyproline excretion were elevated in patients compared with healthy subjects. We suggest that there is reduced bone formation and increased bone resorption in patients with hip fracture.

Acid Phosphatase↗

PubMed1995

Control of ameloblast differentiation.

This review highlights a number of advances towards understanding the sequential developmental cascade of events beginning in the oral ectodermally-derived odontogenic placode and culminating in the formation of the mineralized enamel extracellular matrix. Recent discoveries of growth factors, growth factor receptors and transcription factors associated with instructive epithelial-mesenchymal interactions and subsequent controls for ameloblast cell differentiation are reviewed. The relationship between ameloblast cytology, terminal differentiation and biochemical phenotype are discussed. The tissue-specific gene products characteristic of the ameloblast phenotype as well as their possible functions in formation of the enamel matrix are analyzed as well as the role of maturation-stage ameloblast cells in controlling enamel biomineralization. Finally, pathological conditions in which alterations in the ameloblast or specific gene products result in an abnormal enamel phenotype are reviewed. Clearly, the scientific progress achieved in the last few years concerning the molecular determinants involved in tooth development has been remarkable. However, there remains considerable lack of knowledge regarding the precise mechanisms that control ameloblast differentiation and enamel biomineralization. Anticipated progress continues to require increased international cooperation and collaborations as well as increased utilization of structural biology investigations of enamel extracellular matrix proteins.

Ameloblasts↗

PubMed1994

Association between calcium regulatory hormones and other factors and bone mineral density in elderly Chinese men and women.

BACKGROUND: The purpose of the study was to determine if bone mineral density (BMD) in elderly Chinese subjects was associated with indices of calcium metabolism (parathyroid hormone, vitamin D), osteocalcin, and other nonbiochemical factors. METHOD: 104 men (mean age 74 +/- 6 yrs) and 213 women (mean age 76 +/- 8 yrs) with no previous history of fractures were recruited from old age hostels and community centers. BMD was measured with dual energy X-ray absorptiometry. RESULTS: BMD in both sexes was associated with body mass index (BMI), arm circumference, and skinfold thicknesses. Additionally, in women there was a positive association with grip strength and load-bearing activities, a negative association with age in all sites except for the lumbar spine, and negative associations with indices of bone turnover (osteocalcin, urinary hydroxyproline/creatinine and calcium/creatinine ratios). After adjusting for BMI, women with hypertension or taking antihypertensive drugs had higher mean BMD at the lumbar spine. Multivariate analyses showed that only BMI predicted BMD in men, while age, BMI, and arm circumference were predictors of BMD in women. CONCLUSION: Indices of calcium metabolism were not correlated with BMD in this elderly Chinese population, suggesting that the age-related rise in parathyroid hormone and reduced intestinal absorption of calcium may not be important factors in determining BMD in elderly Chinese men and women.

25-Hydroxyvitamin D 2↗

PubMed1994

Association between serum uric acid and some cardiovascular risk factors in a Chinese population.

The association between serum uric acid concentration and some cardiovascular risk factors was examined in a working Hong Kong Chinese population (mean age 38 years), consisting of 910 men and 603 women. There was no significant age-related rise in serum uric acid concentration. Positive associations were found between serum uric acid concentration and body mass index, waist hip ratio, systolic and diastolic blood pressure, urea, creatinine, protein, glucose (fasting and 2 hours after 75 g oral glucose load), 2 hour insulin, triglycerides, and apolipoprotein B in men. Similar, but fewer, associations were seen in women, with the addition of a positive association with age. In both sexes, serum uric acid was negatively associated with high-density lipoprotein cholesterol. These findings complement the well-known clinical association between gout and cardiovascular and metabolic diseases, such as hypertension, hyperlipidaemia and diabetes mellitus, and suggest that serum uric acid may be a marker for the presence of an adverse cardiovascular risk factor profile.

Adult↗

PubMed1993

Monoclonal antibody directed against colon cancer mucin has high specificity for malignancy.

Exposure of core carbohydrate structures such as NeuAc alpha2-6GalNAc-Ser/Thr (sialosyl-Tn) in mucus glycoproteins is often associated with malignant transformation in a number of different tissues. Reagents that specifically identify such structures would be useful in the diagnosis of cancer. Monoclonal antibody JT10e has been produced against mucins from xenografts of LS174T colon cancer cells but also reacts with mucins of pancreatic cancer xenografts. The following data suggest that JT10e reacts with sialosyl-Tn: (I) reactivity with bovine and ovine submaxillary mucins; (2) reactivity sensitive to neuraminidase or mild acid; (3) inhibition of reactivity by NeuAc and NeuAc alpha2-6 lactose; and (4) lack of reactivity with other glycoproteins with related carbohydrate structures but no sialosyl-Tn. JT10e is distinguishable from 2 other antibodies which react with sialosyl-Tn, B72.3 and TKH2 because JT10e: (a) did not react with normal gastric tissue while B72.3 and TKH2 did; (b) was only partially inhibited by TKH2 and not at all by B72.3; (c) did not react with Tn antigen while B72.3 did; and (d) bound more strongly to pancreatic cancer mucins than did either B72.3 or TKH2. JT10e reacted with a high percentage of malignant colonic, pancreatic, gastric and mammary tissues but not with the corresponding normal tissues. A high percentage of patients with colonic, pancreatic, gastric, mammary and lung cancers had elevated blood levels of JT10e antigen. A number of colonic cancer patients had elevated JT10e antigen levels without corresponding elevations in CA19-9 levels. These results suggest that JT10e antibody could be used in conjunction with other mucin markers to improve the identification of malignancy in colon, and to study the structure of oligosaccharides in cancer mucins.

Animals↗

PubMed1993

The prevalence of diabetes mellitus and impaired glucose tolerance among Hong Kong Chinese adults of working age.

We studied 1513 employees (910 men and 603 women) from a public utility company and a regional hospital to document the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in the Chinese working population of Hong Kong using a 75-g oral glucose tolerance test and World Health Organisation (1985) criteria. The overall prevalence of DM was 4.5 (95% confidence interval: 3.5-5.7%) and that of IGT 7.3 (6.0-8.6%). The prevalence of DM was 5.1 (3.7-6.5%) in men and 3.6 (2.1-5.1%) in women, while that of IGT was 7.4 (5.7-6.5%) in men and 7.1 (5.1-9.1%) in women. The truncated age-adjusted rate of DM for age 30-64 is 7.7% which is comparable to the age-adjusted prevalence rates among Chinese living in Singapore and Mauritius but in marked contrast to the low prevalence rate in Chinese living in Mainland China. Among the diabetic subjects, 38.2% had been previously diagnosed and 32% gave a family history affecting at least one first degree relative. Using polychotomous logistic regression analysis, the independent predictive factors for the development of DM include age (t = 7.31, P < 0.001), family history (t = 5.1, P < 0.001), waist hip ratio (t = 4.05, P < 0.001) and body mass index (t = 4.62, P < 0.001). Our data further confirm that Hong Kong Chinese have a moderate to high susceptibility to non-insulin-dependent diabetes (NIDDM) when exposed to sufficient environmental and lifestyle factors. The high prevalence of IGT indicates a potential for the prevalence of DM to continue to rise unless effective preventive measures are implemented.

Adolescent↗

PubMed1993

Serum lipid profile and its association with some cardiovascular risk factors in an urban Chinese population.

The lipid profile of a Chinese population, which has a lower prevalence of coronary heart disease compared with Caucasians, is studied to determine whether lipid-modifying disease prevention programs are necessary. The study population consisted of 910 men (mean age 36.7 +/- 9.2 yrs) and 603 women (mean age 38.6 +/- 9.1 yrs), who were employees of a public utility company and non-medical staff of a district hospital. Indices of obesity, fasting cholesterol (TC), and its various subfraction, triglycerides (TG), apolipoprotein A-I (Apo A-I), and apolipoprotein B (Apo B) concentrations were measured. Glucose tolerance was also estimated by measuring fasting and 2 h glucose after a 75 g oral glucose load. The lipid profile was similar to that of the North American population, with an overall prevalence of low density lipoprotein cholesterol (LDL-C) > or = 4.1 mmol/L of 21% and 11% in men and women respectively. Similar variations with age, sex, smoking and glucose tolerance compared with Caucasian populations were observed. The high prevalence of subjects with "undesirable" lipid values in this Chinese population, which at present has a coronary artery disease prevalence of one-eighth to one-quarter compared with that in Caucasians, suggests that the incidence of the disease may well rise in the future to pose a similar problem to that in Caucasian populations. Cut off values of lipids conferring increased cardiovascular risks need to be determined in this population, so that public health strategies may be formulated.

Adult↗

PubMed1993

Low prevalence of rheumatoid arthritis in the urbanized Chinese of Hong Kong.

OBJECTIVE: To establish the prevalence of rheumatoid arthritis (RA) in the urbanized Chinese of Hong Kong. METHODS: 2000 adults in 2 housing blocks were screened using a structured interview. Those who screened positive had an examination, rheumatoid factor analysis and radiographs taken. Subjects were classified using the Rome, New York and 1987 ACR criteria (modified and unmodified) for RA. RESULTS: The prevalence of RA, using the modified 1987 ACR criteria, was 0.35%. This is significantly lower than published data for European Caucasians (standardized morbidity ratio = 0.27; 95% CI 0.09-0.63). CONCLUSION: RA is rare in urbanized Chinese.

Adolescent↗

PubMed1992

A comparative investigation of snake venom neurotoxins and their triplet-state tryptophan-disulfide interactions using phosphorescence and optically detected magnetic resonance.

We have investigated the luminescence and optically detected magnetic resonance (ODMR) of the highly homologous snake venom neurotoxins alpha-bungarotoxin (BgTX), alpha-cobratoxin (CbTX), and cobrotoxin (CoTX) in frozen aqueous glasses. The phosphorescence intensity and lifetime of the single invariant tryptophan, Trp29, are found to be diminished in BgTX and CbTx relative to CoTX both at 77 K and at 4.2 K. Selective reduction of the Cys30-Cys34 disulfide proximal to Trp29 in BgTX and CbTX, that is absent in CoTX, results in the enhancement of the phosphorescence to fluorescence intensity ratio of Trp29 and identifies this disulfide as the source of the triplet-state quenching. Variations of the phosphorescence parameters are observed for differently frozen BgTX and CbTX samples. We argue that this observation is consistent with conformational flexibility in the region of Trp29. For BgTX and CbTX, changing the wavelength of excitation from 285 to 300 nm results in a small bathochromic phosphorescence shift of 0.4 nm, an average decrease in the lifetime, and a change in the polarity of the normally positive D-E ODMR signal. From the small excitation-dependent emission shift, we infer that Trp29 is in a relatively hydrophobic environment. The excitation-dependent changes in lifetime and ODMR signal parameters arise from subtle heterogeneity in the disposition of Trp29 with respect to Cys30-Cys34. We discuss the mechanism of disulfide-induced quenching of the Trp29 triplet state in BgTX and CbTX and argue that it most probably is due to electron transfer.

Amino Acid Sequence↗

PubMed1992

Serum intact parathyroid hormone levels in elderly Chinese females with hip fracture.

Serum intact parathyroid hormone (PTH), 25 hydroxyvitamin D(25OHD), 1,25 dihydroxyvitamin D (1,25(OH)2D), albumin, and ionized calcium were measured in 61 Chinese female patients with hip fracture and 61 control subjects. Hip fracture patients had low albumin, ionized calcium, and 250HD levels. Serum PTH and 1,25(OH)2D values were not different between the two groups. We conclude that although 250HD level in hip fracture patients is low, there is no evidence of secondary hyperparathyroidism, suggesting that the low 250HD levels may be a secondary phenomenon in response to the fracture.

Aged↗

PubMed1992

Microalbuminuria and other cardiovascular risk factors in nondiabetic subjects.

The association between urinary albumin:creatinine ratio and other cardiovascular risk factors such as age, blood pressure, obesity, glycemic indices, insulin and lipid profile was examined in a population in a Chinese community consisting of 795 men (mean age 35.8 +/- 8.8 yr) and 538 women (mean age 37.9 +/- 8.9 yr) with a normal glucose tolerance defined by WHO criteria. Men with a urinary albumin:creatinine ratio above the 90th percentile had higher systolic and diastolic blood pressures, fasting plasma glucose, 2-h glucose after a 75 g oral glucose load, and fasting serum insulin. Women with high urinary albumin:creatinine values had higher systolic and diastolic blood pressures, body mass index, waist-hip ratio, fasting insulin and triglycerides. Multivariate analysis showed that only systolic blood pressure and fasting glucose in men, and diastolic blood pressure and fasting insulin in women, independently contributed to urinary albumin:creatinine. When the effect of blood pressure was eliminated by excluding subjects with systolic blood pressure > 140 and diastolic > 90 mm Hg, only fasting insulin was associated with urinary albumin:creatinine in women. No associations were found for men. We conclude that microalbuminuria may be a marker for cardiovascular disease only because of its association with blood pressure in men, while in women, there is an additional independent association with fasting serum insulin.

Adult↗

PubMed1992

Age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of bone metabolism in Chinese women.

OBJECTIVE: To study the age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of calcium metabolism in Chinese women who habitually have a low calcium intake. DESIGN: Cross-sectional study. SUBJECTS: One hundred and fifty-six healthy Chinese women aged 20-83 years. None were on any medication or vitamin supplements. Subjects over the age of 60 years were all living in a hostel; younger subjects were nurses or subjects attending a family clinic for minor illnesses. MEASUREMENTS: Fasting blood and urine samples were collected for biochemical measurements and calcium absorption was measured using 45Ca by the method of Marshall and Nordin. Bone density was measured by dual energy X-ray densitometry (Norland X R20 X-ray bone densitometer) at the left hip and lumbar spine. Serum parathyroid hormone was measured by a chemiluminometric assay. RESULTS: Plasma ionized calcium concentration, alkaline phosphatase, bicarbonate, plasma creatinine and serum B2 microglobulin were significantly higher in the elderly than in the young, whereas plasma phosphate and the anion gap were higher in the young. Urinary excretion of calcium, phosphate and hydroxyproline were all higher in older women. Plasma parathyroid hormone concentration was positively correlated with age even after taking into account the decline in renal function (as indicated by the rise in B2 microglobulin (r = 0.506, P less than 0.001). Serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were not lower in the older women. Fractional calcium absorption from an oral load of radiolabelled calcium was significantly lower in the older women and 37% of the older women were below the 2.5 percentile found in the younger women. Bone density measured by dual energy X-ray densitometry was also significantly lower in the elderly. CONCLUSION: In Chinese women there is an increase in PTH and a decrease in calcium absorption with age in spite of the presence of normal vitamin D metabolites.

Absorption↗

PubMed1992

Elderly subjects aged 70 years and above have different risk factors for ischemic and hemorrhagic strokes compared to younger subjects.

OBJECTIVE: To compare risk factors for ischemic and hemorrhagic strokes in subjects aged 70 years and above with those in younger subjects. DESIGN: Case control study, with controls matched for age and sex in 5-year age groups. SETTING: A general district hospital in Hong Kong with a catchment population of over 1 million. PATIENTS: All patients admitted consecutively over a 6-month period. Classification of stroke was by neurological examination and CT scan, or autopsy if death occurred before CT scanning could be performed. EXCLUSION CRITERIA: onset of ictus greater than 48 hours before admission, those with previous stroke, subarachnoid hemorrhage, or embolic stroke from rheumatic heart disease, and those with liver, renal, biliary, or thyroid diseases. For ischemic strokes, 78 pairs less than 70 years and 121 pairs greater than or equal to 70 years were recruited. For hemorrhagic strokes, the numbers were 40 and 39, respectively. RESULTS: For ischemic strokes, atrial fibrillation and the presence of ischemic heart disease were risk factors only for those aged 70 years and above, while smoking and left ventricular hypertrophy were risk factors only for those below 70 years. Hypertension and glucose intolerance were risk factors for both age groups, although the effect of glucose intolerance was less marked in the older group. No marked difference in serum lipids and lipoproteins as risk factors was observed between the two age groups. Hypertension was the only demonstrable risk factor for hemorrhagic stroke in the younger, but not in the older, group. CONCLUSION: Risk factors for ischemic and hemorrhagic strokes are different in elderly compared with younger subjects, with the possibility that certain risk factors for ischemic strokes, in contrast to those for hemorrhagic strokes, may be modifiable even in subjects aged 70 years or above.

Age Factors↗

PubMed1992

Influence of obesity on plasma fructosamine concentration.

The influence of obesity on plasma fructosamine concentration was studied in 68 diabetic and 1335 nondiabetic subjects from a Chinese community. Obese nondiabetic men (body mass index > 25 kg/m2) had lower fructosamine concentrations than nonobese nondiabetic men (body mass index < or = 25 kg/m2); the pattern was similar for diabetic women. Stepwise multiple-regression analysis showed that, apart from known factors (total protein, albumin, and indices of glycemic control), fructosamine was also associated with body mass index and plasma fasting triglycerides. However, the contribution of these were small except in diabetic women. We conclude that the effect of obesity on fructosamine is small.

Adult↗

PubMed1992

Blood pressure and urinary cations in a Chinese population.

The prevalence of hypertension and the relationship between blood pressure, age, body mass index (BMI) and urinary cations from casual urine specimens were examined in 1,513 Chinese employees of a public utility company and non-medical personnel of a district hospital. The prevalence of hypertension, defined as systolic blood pressure greater than or equal to 140 or a diastolic blood pressure greater than or equal to 90 mmHg, or a past history of hypertension, was 17% in men and 5% in women. After excluding subjects who were on antihypertensive medication, age, body mass index, and urinary sodium/potassium ratio were independently and positively associated with blood pressure, while urinary potassium/creatinine ratio was inversely related to blood pressure. No association with urinary sodium or sodium/creatinine ratio was found. Higher mean blood pressure in men was accompanied by lower urinary potassium/creatinine and potassium concentration and higher sodium/potassium ratio, even though men had the same mean BMI when compared with women. A difference in potassium intake between the sexes may partly account for this finding. We conclude that in this Chinese population, whose dietary intake is more influenced by the West compared with Chinese in the Peoples' Republic of China, age and BMI are important determinants of blood pressure, together with potassium intake as reflected by urinary potassium excretion. No association of blood pressure with sodium excretion was demonstrated.

Adolescent↗

PubMed1992

Association between insulin and blood pressure in a community population with normal glucose tolerance.

The purpose of this study was to examine the relationship between insulin and BP in patients with normal glucose tolerance. The associations between systolic and diastolic BP, age, body mass index, waist/hip ratio, fasting glucose, insulin, fructosamine, glycosylated haemoglobin, lipid profile, and glucose and insulin two hours after 75 g oral glucose were examined in 1,520 employees of a public utility company and non-medical staff of a district hospital. Patients with impaired glucose tolerance or diabetes mellitus (using WHO criteria) were excluded. In men (mean age 35.6 +/- 8.7 years, n = 769), both systolic and diastolic BP were positively associated with age, body mass index, waist/hip ratio, fasting and 2h glucose and insulin, triglycerides and apolipoprotein B, and were negatively associated with glucose/insulin ration, and high density lipoprotein and cholesterol and its subfractions. However, in multivariate analysis only body mass index, age, fasting glucose and insulin were independent predictors of systolic BP, while only body mass index and age predicted diastolic BP. In women, age, glycosylated haemoglobin, 2h glucose/insulin ratio, 2h glucose, fructosamine and triglycerides were predictors of systolic BP. Fasting or 2h insulin, and glucose/insulin ratios did not predict diastolic BP. The results are compatible with the hypothesis that systolic hypertension may reflect a hyper-insulinaemic state even in those with normal glucose tolerance, independent of age and obesity. The association between plasma lipids and blood pressure is probably mediated by insulin and obesity.

Adult↗

PubMed1991

Hypertension, lipoprotein(a), and apolipoprotein A-I as risk factors for stroke in the Chinese.

We analyzed the serum concentrations of lipids and lipoproteins and the prevalence of other risk factors in a case-control study of 304 consecutive Chinese patients with acute stroke (classified as cerebral infarction, lacunar infarction, or intracerebral hemorrhage) and 304 age- and sex-matched controls. For all strokes we identified the following risk factors: a history of ischemic heart disease, diabetes mellitus, or hypertension; the presence of atrial fibrillation or left ventricular hypertrophy; a glycosylated hemoglobin A1 concentration of greater than 9.1%; a fasting plasma glucose concentration 3 months after stroke of greater than 6.0 mmol/l; a serum triglyceride concentration 3 months after stroke of greater than 2.1 mmol/l; and a serum lipoprotein(a) concentration of greater than 29.2 mg/dl. We found the following protective factors: a serum high density lipoprotein-cholesterol concentration of greater than 1.59 mmol/l and a serum apolipoprotein A-I concentration of greater than or equal to 106 mg/dl. The patterns of risk factors differed among the three stroke subtypes. When significant risk factors were entered into a multiple logistic regression model, we found a history of hypertension, a high serum lipoprotein(a) concentration, and a low apolipoprotein A-I concentration to be independent risk factors for all strokes. The attributable risk for hypertension was estimated to be 24% in patients aged greater than or equal to 60 years. In this population, in which cerebrovascular diseases are the third commonest cause of mortality, identification of risk factors will allow further studies in risk factor modification for the prevention of stroke.

Apolipoprotein A-I↗