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Biomedical subjects

E Lau

Publications and source records attributed to E Lau.

At least 73 records · Page 4Linked to original sources

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↗

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↗

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↗

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↗

Isolation and partial characterization of a human amelogenin from a single fetal dentition using HPLC techniques.

A strategy based on high pressure liquid chromatography (HPLC) techniques for the isolation or a principal amelogenin molecule from a single human dentition is described. A partial sequence (33 residues) for this 24 kDa amelogenin is presented and related to earlier studies of human 5 kDa tyrosine-rich amelogenin polypeptides (TRAPs). A failure to identify amino acid residue #25 (tryptophan in other amelogenins) suggests that this 24 kDa amelogenin is the progenitor of the human TRAP-2 molecule and provides further support for the possibility of several human amelogenin gene products, generated by splice-junction selection, from the single amelogenin gene in the same individual. Alternatively, multiple amelogenins may arise by expression of both the AMELX and AMELY loci.

Amelogenin↗

A case control study of some hematological and biochemical variables in acute stroke and their prognostic value.

Hematocrit, total white cell and platelet counts, plasma urea and creatinine concentrations were estimated in 291 patients (mean age 70 +/- 12 years) admitted consecutively over a 6-month period to a district general hospital with acute stroke. Urinary albumin/creatinine ratio was also determined in a subgroup of patients during a follow-up visit 3 months after ictus. Results were compared with those from age- and sex-matched community controls. Total white cell count was elevated in all types of stroke compared with values from control subjects. Platelet count, plasma urea and creatinine concentrations were higher and the plasma albumin/globulin ratio was lower among patients with ischemic stroke. Elevated total white cell count, urea and creatinine, which were of prognostic significance, were found to be associated with the severity of stroke as indicated by the Glasgow coma score, and did not have any independent prognostic value. Elevated hematocrit was not shown to be a risk factor and did not have any prognostic significance. A low plasma albumin/globulin ratio, an index of plasma viscosity, was a possible risk factor for ischemic strokes. Urinary albumin/creatinine ratios in the highest quintile increased the risk of stroke 13-fold.

Aged↗

Biochemical predictors for osteoporotic fractures in elderly Chinese--a longitudinal study.

In a longitudinal study of 283 elderly subjects aged 60 years or over living in the community, 9 subjects (7 women and 2 men) developed osteoporosis-related fractures in 30 months. These subjects initially had higher random urinary hydroxyproline/creatinine and calcium/creatinine ratios, and lower plasma 25-hydroxyvitamin D concentrations. These biochemical variables may be useful predictors of osteoporosis-related fractures and may provide a suitable community screening method to identify those most at risk.

25-Hydroxyvitamin D 2↗

Some biochemical indices of bone turnover in elderly Chinese.

Biochemical indices of bone turnover were determined in a cluster sample of 427 apparently healthy elderly subjects aged 60 years and over. Plasma calcium concentrations corrected for albumin were not significantly different between elderly men and women, but were higher compared with values in younger Chinese of the same sex. The prevalence of hypercalcemia (greater than 2.75 mmol/L) in the elderly (0.2%) was lower than in Caucasian populations. Plasma phosphate concentrations were higher in women, but lower than in young adults. Plasma alkaline phosphatase activity was higher in women compared with values for men, and higher compared with values for young adults. Plasma 25-hydroxyvitamin D was lower in elderly women than elderly men, but was similar to values in younger subjects. Urinary calcium: creatinine and hydroxyproline: creatinine ratios were higher in women. The values were comparable to those for Caucasian postmenopausal women, suggesting that Chinese elderly subjects had similar bone turnover rates.

Adult↗

Physical activity and calcium intake in fracture of the proximal femur in Hong Kong.

In Hong Kong physical activity and calcium intake of 400 Chinese men and women with hip fractures were compared with those of 800 controls. Daily walking outdoors, upstairs, uphill, or with a load protected against fracture. This was independent of cigarette smoking and alcohol consumption. Higher levels of reported activity in middle life were also protective. Average calcium intake was around one quarter that in Britain because of the low consumption of dairy products. Differences in calcium intake depended mainly on consumption of green vegetables and small fish. High intake protected against hip fracture. These findings point to the importance of maintaining daily physical activity and calcium intake in urbanised Chinese populations.

Aged↗

Histopathology of the mandibular condyle.

Histological sections of mandibular condyles surgically removed from 40 female and 12 male patients who failed to respond to conservative management of temporomandibular joint related problems were examined. The proliferation, intermediate and cartilage zones were frequently either partly or completely absent in older subjects confirming previously held views of the functional significance of these zones. There was no obvious sex differences in the histological appearance of the condyle and evidence of inflammatory change was rarely seen.

Adolescent↗

Insulin-like growth factor I/somatomedin C (IGF-I/Sm C): comparison of natural, solid phase synthetic and recombinant DNA analog peptides in two radioligand assays.

Investigation of the biologic activity of Insulin-like Growth Factor I/Somatomedin C (IGF-I/Sm C) has been hampered by the scarcity of purified material. The synthesis of this molecule by the solid phase procedure and an analog of IGF-I/Sm C by recombinant DNA technology offers promise that studies of the biologic activity of IGF-I/Sm C will soon be possible. We have found that natural IGF-I/Sm C and the two synthetic peptides behave similarly in two radioligand systems, providing evidence that these molecules possess the requisite structural integrity for use in such biological studies.

Humans↗

Glycosaminoglycans in embryonic mouse tooth germs. A histochemical analysis.

Glycosaminoglycans (GAG) were localized in embryonic mouse molars by Alcian-blue staining in a critical-electrolyte-concentration (CEC) method (Scott and Dorling, 1965). Sulfated GAG were distinguished from hyaluronate (HA) by combining the binding specificity of Alcian blue and substrate specificity of GAG-lytic enzymes. The stratum reticulum was found to contain a small amount of HA, but no chondroitin sulfate (CS). The amount of HA decreased gradually during odontogenesis. No GAG were detected in the outer and inner dental epithelia. The basement membrane and the predentine were intensely stained, and shown to be rich in HA and CS. The preodontoblastic layer contained small amounts of HA and CS. These decreased progressively during odontogenesis. No GAG was found at the odontoblastic layer. The lower dental papilla contained a constant amount of HA (the major component) and CS.

Animals↗

Advantages in the use of L-asparaginase-albumin polymer as an antitumor agent.

Polymeric conjugates of L-asparaginase and an excess of homologous albumin were compared with free L-asparaginase for antitumor activity using a mouse model 6C3HED lymphosarcoma and a human pancreatic tumor cell line, PANC-1. The asparaginase-albumin polymer is more resistant to proteolytic degradation compared to equivalent amounts of free enzyme and is more effective as an antitumor agent in prolonging survival of C3H/HeJ mice receiving 6C3HED lymphosarcoma. In terms of antitumor activity, the enzyme is approximately 20 times more effective, compared to free enzyme, when given in polymeric form with albumin. Similarly, the polymeric form of L-asparaginase is more effective in inhibiting cell growth of human pancreatic tumor cells grown in tissue culture. The increased effectiveness of the polymeric form of L-asparaginase is probably related to its resistance to biodegradation. The use of cell surface-specific monoclonal antibodies to target the polymer to tumor cells is also demonstrated.

Albumins↗

Effects of CCNU on hematopoiesis in rats.

The effect of orally administered CCNU on proliferating and cytokinetically "resting" bone marrow cells was studied in rats. The resting bone marrow cells were selectively labeled with 3H-thymidine by the "complete 3H-thymidine labeling method." The results show a reduction in the number of absolute bone marrow cells to about 40% of the original value in 3 days. Regeneration was completed only after 22 days. No difference was found in the destructive or the regenerative pattern of CFU-C, myelopoietic, erythropoietic, lymphatic, or megakaryocytic cells. Resting and proliferating cells of the bone marrow were equally affected by CCNU.

Animals↗