Hyperlipidemias: Tomlinson B

Critchley JA, Zhao HL, Tomlinson B, Leung W, Thomas GN, Chan JC, Cockram CS. · Divisions of Clinical Pharmacology and Endocrinology, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, Hong Kong, China. · Chin Med J (Engl). · Pubmed #11930647 links to  free full text

Abstract: PURPOSE: To review evidence-based management of nephropathy in patients with type 2 diabetes. DATA SOURCES: A literature search (MEDLINE 1966 to 2000) was performed using the key word "diabetic nephropathy". Relevant book chapters were also reviewed. STUDY SELECTION: Well-controlled, prospective landmark studies and expert review articles on diabetic nephropathy were selected. DATA EXTRACTION: Data and conclusions from the selected articles that provide solid evidence to the optimal management of diabetic nephropathy were extracted and interpreted in light of our clinical research experience with many thousands of Hong Kong Chinese patients. RESULTS: Hypertension, long diabetes duration, poor glycaemic control and central obesity are the most important risk factors. Microalbuminuria is a practical marker to predict overt nephropathy in type 2 diabetic patients. Risk factor modification, renal function monitoring and combined therapies are the current integrated approaches to manage patients with diabetic kidney disease. Optimal glycaemic control is the mainstay of treatment but effective antihypertensive therapy is also key to delaying the progression of diabetic nephropathy. Angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists have important renoprotective actions independent of their blood pressure lowering actions. CONCLUSIONS: Diabetic nephropathy is the leading cause of end-stage renal disease worldwide. Monitoring renal function and screening for microalbuminuria will allow the identification of patients with nephropathy at a very early stage for intervention. Tight glycaemic control and aggressive antihypertensive treatment as well as the use of renin-angiotensin system inhibitors should substantially delay the progression of nephropathy.

Lee KK, Lee VW, Chan WK, Lee BS, Chong AC, Wong JC, Yin D, Alemao E, Tomlinson B. · School of Pharmacy, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China. · Value Health. · Pubmed #18387073 No free full text.

Abstract: OBJECTIVE: We sought to determine 1) long-term lipid-lowering treatment patterns; 2) cholesterol goal attainment rates and possible determinants of goal achievement; and 3) effects of cholesterol goal attainment on coronary events in hospitalized Hong Kong patients. METHODS: In this retrospective cohort analysis, records of two public Hong Kong hospitals were reviewed for 196 adults (69% with coronary heart disease (CHD) or CHD-risk equivalent) who received at least one lipid-lowering therapy during hospitalization. Low-density lipoprotein cholesterol (LDL-C) targets were <2.6 mmol/l (<100 mg/dL) for patients with CHD or CHD risk equivalents and <3.37 mmol/l (<130 mg/dL) for those without. RESULTS: Most participants were initiated on regimens of low to midequipotency doses and never had their regimens adjusted to higher potency. Approximately 44% of patients not at LDL-C at baseline failed to achieve goal during a median follow-up of 1.9 years. Patients with higher coronary risk and/or LDL-C levels at baseline were less likely than their lower-risk counterparts to achieve goal; for each 1-mmol/l (38.7-mg/dL) increase in LDL-C at baseline, the likelihood of attaining goal declined by 64%. Patients achieving cholesterol goal had significantly longer cardiovascular event-free times. CONCLUSIONS: A total of 44% of Hong Kong patients not at LDL-C goals at baseline did not achieve them over 1.9 years. More effective and well-tolerated therapies, including adjunctive regimens (e.g., ezetimibe-statin, niacin-statin), may be necessary to enhance LDL-C goal achievement and increase event-free time.

Zhu JR, Tomlinson B, Ro YM, Sim KH, Lee YT, Sriratanasathavorn C. · Zhongshan Hospital, Fudan University, Shanghai, China. · Curr Med Res Opin. · Pubmed #18196620 No free full text.

Abstract: BACKGROUND: Most studies investigating the benefits of statins have focused on North American and European populations. This study focuses on evaluating the lipid-lowering effects of rosuvastatin and atorvastatin in Asian patients. OBJECTIVES: The DIrect Statin COmparison of LDL-C Values: an Evaluation of Rosuvastatin therapY (DISCOVERY)-Asia study is one of nine independently powered studies assessing the efficacy of starting doses of statins in achieving target lipid levels in different countries worldwide. DISCOVERY-Asia was a 12-week, randomised, open-label, parallel-group study conducted in China, Hong Kong, Korea, Malaysia, Taiwan, and Thailand. RESULTS: A total of 1482 adults with primary hypercholesterolaemia and high cardiovascular risk (> 20%/10 years, type 2 diabetes, or a history of coronary heart disease) were randomised in a 2 : 1 ratio to receive rosuvastatin 10 mg once daily (o.d.) or atorvastatin 10 mg o.d. The percentage of patients achieving the 1998 European Joint Task Force low-density lipoprotein cholesterol (LDL-C) goal of < 3.0 mmol/L at 12 weeks was significantly higher in the rosuvastatin group (n = 950) compared with the atorvastatin group (n = 471) (79.5 vs. 69.4%, respectively; p < 0.0001). Similar results were observed for 1998 European goals for total cholesterol (TC), and the 2003 European goals for LDL-C and TC. LDL-C and TC levels were reduced significantly more with rosuvastatin compared with atorvastatin. Both drugs were well-tolerated and the incidence and type of adverse events were similar in each group. TRIALS REGISTRATION: The trial registry summary is available at http://www.clinicaltrials.gov/; ClinicalTrials.gov Identifier: NCT00241488 CONCLUSIONS: This 12-week study showed that the starting dose of rosuvastatin 10 mg o.d. was significantly more effective than the starting dose of natorvastatin 10 mg o.d. at enabling patients with primary hypercholesterolaemia to achieve European goals for LDL-C and TC in a largely Asian population in real-life clinical practice. The safety profile of rosuvastatin 10 mg is similar to that of atorvastatin 10 mg in the Asian population studied here, and is consistent with the known safety profile of rosuvastatin in the white population.

Wong KS, Ng PW, Tang A, Liu R, Yeung V, Tomlinson B. · Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. · Neurology. · Pubmed #17548555 No free full text.

Abstract: We used transcranial Doppler to screen 3,057 patients who had at least one vascular risk factor of hypertension, diabetes, or hyperlipidemia and found 385 (12.6%) had middle cerebral artery stenosis. Elderly, hypertension, diabetes, and hyperlipidemia were associated factors. The prevalence escalated quadratically with increasing number of associated factors: from 7.2% for one, to 29.6% for four associated factors. Asymptomatic middle cerebral artery stenosis is common in patients with vascular risk factors.

Cheng CW, Chan JC, Tomlinson B, Woo KS, You JH. · School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT, China. · Int J Clin Pharmacol Ther. · Pubmed #17063979 No free full text.

Abstract: 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.

Ma YQ, Thomas GN, Tomlinson B. · Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. · Int J Cardiol. · Pubmed #15982502 No free full text.

Abstract: INTRODUCTION: Two MspI polymorphisms in the ApoA-I gene (G-75A and C83T) have been shown to be associated with plasma HDL-cholesterol levels. METHODS: We used a PCR-based RFLP method to determine the association of these polymorphisms with lipid parameters in 271 non-diabetic, normotriglyceridaemic Chinese subjects, of whom 104 were patients with hypertension, with 10.2% having hypercholesterolaemia and the remainder were controls. RESULTS: As expected, the hypertensive group had higher blood pressure and indices of obesity, and a more adverse lipid profile. No differences in the ApoA-I G-75A genotype or allele frequency distributions between the controls and patients were identified. However, there was a significantly lower frequency of the CT genotype (p=0.012) and T allele (p=0.011) in the affected subjects with hypercholesterolaemia or hypertension. Similarly, blood pressure and triglyceride levels were significantly lower and HDL-cholesterol levels significantly higher in the subjects with the CT genotype compared to those with the CC genotype (p<0.05). However, the G-75A genotypes did not appear to influence the lipid or blood pressure levels. The -75A allele frequency was higher in our healthy controls than an equivalent Caucasian population (31.1% vs. 18.3%, p<0.001), whereas the 83T allele frequency was similar between the healthy Chinese and Caucasian groups. CONCLUSION: The 83T allele may be associated with a better lipid profile and blood pressure levels in this group of Chinese subjects.

Thomas GN, Hong AW, Tomlinson B, Lam CW, Critchley JA, Sanderson JE, Woo J, Lau E. · Department of Medicine and Therapeutics, The Chinese University of Hong Kong Prince of Wales Hospital, Shatin, Hong Kong. · Diabetes Res Clin Pract. · Pubmed #15063605 No free full text.

Abstract: OBJECTIVE: To investigate the impact of insulin resistance on cardiovascular risk factors in the elderly. RESEARCH DESIGN AND METHODS: A cross-sectional, community-based study of 225 older Chinese participants (65-74 years, 55.6% female) recruited from community centres for the elderly in Shatin. Anthropometric measures and DXA body fat, blood pressure, insulin sensitivity (fasting insulin, fasting insulin-glucose product, short insulin tolerance test (SITT)), glycaemic (fasting glucose, glycated haemoglobin A1c) and lipid (total, HDL-, and LDL-cholesterol, triglycerides) indices and albuminuria (24h albumin-to-creatinine ratio) were measured. RESULTS: There was a close correlation between the SITT and insulin-glucose product indices of insulin resistance. Decreasing tertiles of insulin sensitivity were associated with increasing indices of glycaemic control, and general and central obesity, including DXA lean and fat mass, albuminuria, and triglycerides, with decreasing HDL-cholesterol. There were no differences in blood pressure or electrolyte levels between these tertile groups. These subjects were more insulin resistant than a group of younger diabetics. CONCLUSIONS: Insulin resistance was associated with indices of obesity and an atherogenic lipid and hyperglycaemic profile and may in part contribute to the high frequency of metabolic syndrome components in these older Chinese subjects.

Yang T, Pang CP, Tsang MW, Lam CW, Poon PM, Chan LY, Wu XQ, Tomlinson B, Baum L. · Department of Chemical Pathology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. · Hum Mutat. · Pubmed #12655575 No free full text.

Abstract: Elevated plasma triglyceride and nonesterified fatty acid concentrations may cause insulin resistance. Lipoprotein lipase (LPL) is a rate-determining enzyme in lipid metabolism. To investigate the role of the LPL gene in Chinese patients with hypertriglyceridemic type 2 diabetes, 277 patients with type 2 diabetes and 241 healthy control subjects were recruited and screened for sequence changes in the LPL gene by PCR, SSCP, restriction analysis and direct DNA sequencing. Ten mutations were identified: four missense mutations, Ala71Thr, Val181Ile, Gly188Glu and Glu242Lys; one nonsense mutation Ser447Ter; and five silent mutations. Ser447Ter was found in both patients and controls with no significant difference in frequency. The four missense mutations were located in the highly conserved exon 3, 5, and 6 regions and in highly conserved amino acid sites. They led to reduced LPL mass and enzyme activities in both post-heparin plasma and in vitro expression. The modeled structures displayed major differences between the mutant and wildtype molecules. These results indicated that the four missense mutations lead to LPL deficiency and subsequent hypertriglyceridemia. Based on our study and published data, a putative pathogenic pathway was suggested: LPL enzyme deficiency causes elevated plasma triglyceride level and subsequent insulin resistance; both increased free fatty acids and insulin resistance promote gluconeogenesis and hyperglycaemia, a vicious circle leading to type 2 diabetes.

Chan LY, Lam CW, Mak YT, Tomlinson B, Tsang MW, Baum L, Masarei JR, Pang CP. · Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong, China. · Hum Mutat. · Pubmed #12204001 No free full text.

Abstract: We screened 160 unrelated Chinese hypertriglyceridemic subjects for sequence alterations in the promoter and the 10 exons of the lipoprotein lipase (LPL) gene. We identified one reported mutation (L252R), one common polymorphism (S447X), and six novel mutations: V181I, C283Y, S298R and S338F (found in single individuals), L252V (in two individuals), and A71T (in three individuals). Screening of family members of the above probands revealed a total of 19 mutation carriers, most of whom, though not all, displayed reduced LPL activity and mass when compared to normolipidemic control subjects. In in vitro expression studies, A71T, V181I, L252R, L252V and C283Y decreased the specific activity of the gene product. Interestingly, S298R had no effect on the catalytic activity while S338F increased it. A71T and C283Y reduced the secretion of the mutant proteins significantly while V181I, S298R and S338F had mild effects only. The total LPL mass of all the mutant constructs was reduced compared to that of the wild type construct, probably due to the instabilities of the mutant mRNA or the mutant protein. The heterogeneity in phenotypic effects of these mutations is a likely consequence of their variable effects on proteoglycan binding, conformation and interactions with other secondary genetic or environmental factors.

Lee ZS, Critchley JA, Ko GT, Anderson PJ, Thomas GN, Young RP, Chan TY, Cockram CS, Tomlinson B, Chan JC. · Department of Medicine and Therapeutics, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin. · Obes Rev. · Pubmed #12164469 No free full text.

Abstract: The purpose of this cross-sectional study was to examine the risk associations between obesity indexes [body mass index (BMI) and waist circumference (WC)], cardiovascular risk factors [plasma glucose and lipids, blood pressure and urinary albumin excretion (UAE)] and morbidity conditions (Type 2 diabetes mellitus, hypertension, dyslipidaemia and/or albuminuria) in Hong Kong Chinese. Seven-hundred and two Hong Kong Chinese subjects (18-65 years of age, 59.4% of whom had at least one morbidity condition) were recruited from the Prince of Wales Hospital, Hong Kong SAR. The measurements taken of the subjects included: height; weight; waist and hip circumferences; blood pressure; fasting plasma glucose and lipids; and 24-h UAE. The mean BMI was 22.4 and 25.7 kg m(-2) in healthy subjects and patients, respectively. The mean WC measurements of healthy subjects and patients were 77.1 and 86.4 cm in males and 71.0 and 81.8 cm in females, respectively. There were increasing trends between obesity indexes and the severity of cardiovascular risk factors and the prevalence of morbidity conditions (all P-values for trend <0.05). Using 19.0-20.9 kg m(-2) and <70 cm as a referent, subjects with a BMI of > or =25.0 kg m(-2) (in both sexes) and/or a WC of > or =85 cm in males and > or =75 cm in females had an age-adjusted odds ratio between 3.2 and 4.4 for the occurrence of at least one morbidity condition. Patients with a greater number of comorbidities also had higher BMI and WC measurements (all P-values for the trend were <0.05 with adjustment for age and gender). Hence, despite Hong Kong Chinese being less obese than Caucasians, the intimate relationships among obesity, cardiovascular risk factors and morbidity conditions remain. Our data support using lower BMI and WC levels to define obesity and its associated health risks rather than using the criteria established from Caucasians who generally have larger body frames.

Lee ZS, Critchley JA, Tomlinson B, Young RP, Thomas GN, Cockram CS, Chan TY, Chan JC. · Department of Medicine and Therapeutics, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories. · Metabolism. · Pubmed #11229419 No free full text.

Abstract: The metabolic syndrome is characterized by a clustering of cardiovascular risk factors including type 2 diabetes mellitus, hypertension, dyslipidemia, and obesity. Elevated plasma insulin and urinary norepinephrine (noradrenaline) and reduced urinary epinephrine (adrenaline) excretion are associated with obesity in Caucasian populations. We examined the interrelationships between obesity, plasma insulin, and urinary catecholamine excretion in Chinese subjects with various components of the metabolic syndrome. A total of 577 Chinese subjects (aged 38 +/- 10 years; 68% with type 2 diabetes mellitus, hypertension, dyslipidemia, obesity, and/or albuminuria and 32% healthy subjects) were studied, all of whom had a plasma creatinine less than 150 micromol/L. The blood pressure, height, weight, waist and hip circumference, and fasting plasma glucose, insulin, lipid, and creatinine levels were measured. A 24-hour urine sample was collected for measurement of albumin and catecholamine excretion. The body mass index (BMI) and waist circumference were used as measures of general and central obesity, respectively. The insulin resistance index was estimated by the calculated product of fasting plasma insulin and glucose concentrations. Patients with an increasing number of components of the metabolic syndrome (type 2 diabetes mellitus, hypertension, dyslipidemia, obesity, and/or albuminuria) were more obese, hyperglycemic, dyslipidemic, and albuminuric and had higher blood pressure, plasma insulin, insulin resistance indices, and 24-hour urinary norepinephrine excretion but lower urinary epinephrine output (all P < .005). Increasing quintiles of BMI in the whole population or waist circumference in both sexes were associated with increasing trends for adverse lipid profiles, plasma insulin, insulin resistance indices, and urinary norepinephrine excretion but a decreasing trend for urinary epinephrine output (all P < .001). There were close associations between age, obesity, blood pressure, fasting plasma glucose, lipid, insulin, insulin resistance indices, and urinary catecholamine excretion. Using stepwise multiple regression analysis (all P < .001), 34% of the variability of the BMI and 45% of that of the waist circumference were independently related to gender (waist higher in males and BMI higher in females), increased plasma insulin, triglyceride, and urinary norepinephrine excretion, and decreased high-density lipoprotein (HDL) cholesterol and urinary epinephrine output. In Chinese subjects with different manifestations of the metabolic syndrome, hyperinsulinemia, insulin resistance, elevated norepinephrine, and reduced epinephrine excretion were closely associated with general and central obesity. Based on these findings, we postulate that complex interactions between the insulin and sympathoadrenal systems may lead to the development of obesity and the metabolic syndrome.

Thomas GN, Tomlinson B, Chan JC, Sanderson JE, Cockram CS, Critchley JA. · Department of Medicine and Therapeutics, The Chinese University of Hong Kong, The Prince of Wales Hospital, Shatin. · Diabetes Care. · Pubmed #11213892 links to  free full text

Abstract: OBJECTIVE: In Chinese populations, hypertension is common and is a major risk factor for cerebrovascular and coronary heart disease, particularly when associated with diabetes. The clustering of these disorders and dyslipidemia and obesity is termed the metabolic syndrome and is increasing in prevalence in the populations of modernizing Asian nations. The renin-angiotensin system (RAS) helps maintain blood pressure and salt homeostasis and may play a role in the pathogenesis of aspects of the metabolic syndrome. We investigated three RAS gene polymorphisms--the ACE insertion/deletion (I/D), angiotensinogen (AGT) M235T, and angiotensin II type 1 receptor (AT1R) A1166C polymorphisms--for a possible role in modulating these disorders in 853 Chinese subjects with varying components of the metabolic syndrome. RESEARCH DESIGN AND METHODS: The three gene polymorphisms of this cross-sectional study were detected using polymerase chain reaction-based protocols. The genotype frequencies were compared between the controls (n = 119) and both overlapping and nonoverlapping groups of patients with type 2 diabetes, hypertension, and dyslipidemia using chi2 test. Differences in levels of the biochemical parameters between the genotypes were determined using analysis of variance. RESULTS: No significant relationship was identified between these polymorphisms and blood pressure in this population. Although the AT1RA1166C polymorphism was not associated with any aspect of the metabolic syndrome examined, there was limited evidence to suggest that the AGT M235T polymorphism may be associated with cholesterol levels. The ACE I allele was significantly more frequent in each group comprising subjects with type 2 diabetes/glucose intolerance (GIT), and the I allele was associated with higher fasting plasma glucose levels. CONCLUSIONS: These findings suggest that these polymorphisms are unlikely to be involved in the pathogenesis of hypertension. The ACE I/D polymorphism was associated with the metabolic syndrome, having a higher frequency of I allele-containing genotypes in those groups, but this appeared to result predominantly from the relationship with type 2 diabetes/GIT in this population of Chinese subjects.

Thomas GN, Critchley JA, Tomlinson B, Anderson PJ, Lee ZS, Chan JC. · Department of Medicine and Therapeutics, The Prince of Wales Hospital, Shatin, Hong Kong SAR, People's Republic of China. · Metabolism. · Pubmed #11145111 No free full text.

Abstract: Obesity and insulin resistance are considered important links underlying the development of hypertension. In Caucasians, there have been many reports of an association between insulin resistance and hypertension. However, this relationship is not consistently found in other ethnic groups. In this study, we examined the involvement of insulin resistance (assessed as fasting insulin-glucose product, FIGP) and general and central obesity as potential links in the development of hypertension in 413 normoglycemic Hong Kong Chinese (56.9% hypertensive) subjects. Anthropometric parameters (waist circumference [WC], waist-to-hip ratio [WHR], body mass index [BMI]), surrogate measures of insulin resistance (fasting plasma glucose, insulin, FIGP), fasting lipids and systolic (SBP) and diastolic (DBP) blood pressure were measured. Both male and female hypertensives were more obese and dyslipidemic, and the females had higher indices of insulin resistance than the normotensive subjects of the same gender. Before adjustment for age, gender, and adiposity, FIGP correlated with SBP in the total (r = .19, P = .009) and low BMI (r = .23, P < .05) and low WHR (r = .25, P < .01) groups. However, after adjustment, there was no significant relationship between FIGP and blood pressure. In contrast, BMI and WC were strongly associated with blood pressure (r > or = .41, P < .001 for both DBP and SBP in the total population), although in the group with general obesity, the strength of the relationship was weaker (r > or = .13). These relationships persisted after adjustment for age, gender, and FIGP. Obesity, therefore, appears to have a predominant role compared with insulin resistance in determining blood pressure in these normoglycemic Chinese.

Lee SC, Pu YB, Thomas GN, Lee ZS, Tomlinson B, Cockram CS, Critchley JA, Chan JC. · Department of Medicine and Therapeutics, The Chinese University of Hong Kong, The Prince of Wales Hospital, Shatin. · Metabolism. · Pubmed #10954020 No free full text.

Abstract: Tumor necrosis factor alpha (TNF-alpha) is a multifunctional cytokine constitutively produced by adipose tissue that may mediate insulin resistance. Studies in Caucasian subjects have suggested that the G-308A transition in the 5' region of the TNF-alpha gene may be associated with insulin resistance and obesity. These factors have been proposed to underlie the clustering of type 2 diabetes, hypertension, and dyslipidemia found in the metabolic syndrome, the prevalence of which is reaching epidemic proportions in Hong Kong Chinese. We investigated the association of this gene polymorphism with the components of the metabolic syndrome including the lipid profile, as well as with the indices of obesity and insulin resistance as measured by the insulin-glucose product, in 440 Chinese subjects (healthy [27.5%] and overlapping groups with type 2 diabetes [54.1%], hypertension [38.8%], dyslipidemia [39.3%], or obesity [39.5%]). The frequency of the mutant A allele was 7.4% in 121 healthy controls and 9.0% in the total population. The mutation was not associated with any component of the metabolic syndrome or with the prevalence of albuminuria and retinopathy in these subjects. Furthermore, there was no difference in anthropometric measures, insulin resistance, or lipid levels between subjects with the GG genotype and those with the mutant allele. In summary, the TNF-alpha gene G-308A polymorphism is unlikely to play an important role in the development of these disorders in this population.

Lee ZS, Critchley JA, Chan JC, Anderson PJ, Thomas GN, Ko GT, Young RP, Chan TY, Cockram CS, Tomlinson B. · Divisions of Clinical Pharmacology and Endocrinology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. · Hong Kong Med J. · Pubmed #10793398 links to  free full text

Abstract: OBJECTIVES: To examine the interrelationships between obesity and various cardiovascular risk factors, and to investigate the relative importance of insulin and obesity in their associations with various pathophysiologies. DESIGN: Cross-sectional clinic-based study. SETTING: Medical clinics at a university teaching hospital, Shatin, Hong Kong. PARTICIPANTS: A heterogeneous cohort of 767 Hong Kong Chinese subjects with a mean age of 43 (standard deviation, 14) years. MAIN OUTCOME MEASURES: Body mass index, waist circumference, plasma insulin, insulin resistance index, fasting plasma glucose and lipid levels, blood pressure, and 24-hour urinary albumin excretion. RESULTS: Pathophysiological abnormalities and risk factors are frequently clustered to varying degrees. Compared with the control subjects, patients with at least one component of the metabolic syndrome were more obese, hyperinsulinaemic, insulin resistant, hyperglycaemic, hypertensive, dyslipidaemic, and albuminuric (all variables, P<0.001). Increasing degrees of body mass index, waist circumference, plasma insulin level, and insulin resistance index were associated with an increasing number of risk factors after adjusting for age and sex (all variables, P<0.02). Multiple regression analysis showed that obesity, as reflected by either the body mass index or waist circumference, had a closer association than plasma insulin with the fasting plasma glucose concentration, blood pressure, and high-density lipoprotein-cholesterol and triglyceride concentrations. Using 19.0-20.9 kg/m(2) as the reference body mass index interval, the lowest cardiovascular risk was associated with a body mass index of <23.0 kg/m(2). There was an increased risk of 3.1 and 5 times when the body mass index was 23. 0-24.9 kg/m(2) and > or =25 kg/m(2), respectively. CONCLUSIONS: Obesity, hyperinsulinaemia, and insulin resistance are characteristic features of Hong Kong Chinese patients who have various components of the metabolic syndrome. Obesity has a greater effect than plasma insulin on various pathophysiologies.

Chan L, Mak Y, Tomlinson B, Baum L, Wu X, Masarei J, Pang C. · Chinese University of Hong Kong, Hong Kong. · Eur J Clin Invest. · Pubmed #10619999 No free full text.

Abstract: BACKGROUND: We investigated lipoprotein lipase (LPL) gene mutations in a Chinese male with severe hypertriglyceridemia and recurrent pancreatitis. METHODS: We screened for LPL sequence mutation in the LPL gene in this patient, his relatives and 160 unrelated hypertriglyceridaemic subjects. We determined the postheparin plasma LPL activity of subjects carrying a LPL mutation and studied the in vitro expression of mutant LPL in COS-1 cells. RESULTS: The proband was found to be a compound heterozygote for a novel Leu252Val and a reported Leu252Arg mutation in the LPL gene. He had low plasma levels of postheparin LPL activity and mass. The two mutations segregated independently in his family. In vitro expression analysis showed that Leu252Arg abolished both the catalytic function and secretion of LPL, while Leu252Val abolished the catalytic function but only reduced secretion by about half. We have also detected heterozygous Leu252Val and Leu252Arg mutations each in one hypertriglyceridaemic individual. CONCLUSION: These results indicated that the leucine 252 is critical for the catalytic activity and secretion of LPL. Why the substitution by valine instead of arginine resulted only in a partial suppression of LPL secretion, remains to be investigated. Leu252Val and Leu252Arg are the likely cause of hypertriglyceridemia in these subjects because of their deleterious effects on LPL activity or secretion. Leu252Val/Leu252Arg is the first compound heterozygous mutation known to occur in the same codon of the LPL gene. So far they are found only in Chinese.

Tomlinson B, Lan IW, Hamilton-Craig I. · No affiliation provided · BMJ. · Pubmed #11349660 links to  free full text

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