Significant increase in high-density lipoprotein cholesterol with fibrates is associated with low pretreatment high-density lipoprotein cholesterol: findings from an outpatient clinic setting.

BACKGROUND: Change in high-density lipoprotein cholesterol (HDL-C) observed in large randomized controlled trials using fibrates has varied. Inconsistent cardiovascular outcomes have also been the common theme of these trials. Subgroup analysis of even the negative trials, however, reveals significant reduction in cardiovascular disease in patients with low HDL-C and high triglycerides. We wished to study HDL-C change following fibrate therapy in our lipid clinic and determine the factors associated with HDL-C change. METHODS: Data were collected from case notes of patients started on fibrates (n=248) between 2002 and 2008 in the lipid clinics at Heart of England NHS Foundation Trust. Regression analyses were carried out to determine factors associated with changes in HDL-C. RESULTS: Linear regression analysis revealed that HDL-C change was associated with pretreatment HDL-C (P<0.001), diabetes (P=0.004) and treatment duration (P=0.036). Multiple regression analysis with all of the factors in the model suggested that they were independent. Patients with a baseline HDL-C <1.0 mmol/L showed a greater HDL-C increase when compared to patients with a baseline HDL-C ≥1.0 mmol/L; HDL-C <1.0 mmol/L (increase of 0.15 mmol/L, linear regression: c=0.14, 95% confidence interval 0.05-0.30, P<0.001) and HDL-C ≥1.0 (increase of 0.002 mmol/L, linear regression: reference category). A similar relationship between change in HDL-C and baseline HDL-C was observed within groups stratified by patient characteristics (apart from those on concurrent statin therapy and females). CONCLUSIONS: Our results may explain the discrepancies observed in some randomized controlled trials whereby subgroup analysis of patients with the metabolic syndrome appeared to show benefit whereas this was absent in the total cohort. Thus, future interventional studies using fibrates should perhaps focus on patients with low HDL-C levels.

Serum leptin and its relation to anthropometric measures of obesity in pre-diabetic Saudis.

BACKGROUND: Little information is available on leptin concentrations in individuals with IGT. This study aims to determine and correlate leptin levels to anthropometric measures of obesity in pre-diabetic, (IFG and IGT), type 2 diabetic and normoglycaemic Saudis. METHODS: 308 adult Saudis (healthy controls n = 80; pre-diabetes n = 86; Type 2 diabetes n = 142) participated. Anthropometric parameters were measured and fasting blood samples taken. Serum insulin was analysed, using a solid phase enzyme amplified sensitivity immunoassay and also leptin concentrations, using radio-immunoassay. The remaining blood parameters were determined using standard laboratory procedures. RESULTS: Leptin levels of diabetic and pre-diabetic men were higher than in normoglycaemic men (12.4 [3.2-72] vs 3.9 [0.8-20.0] ng/mL, (median [interquartile range], p = 0.0001). In females, leptin levels were significantly higher in pre-diabetic subjects (14.09 [2.8-44.4] ng/mL) than in normoglycaemic subjects (10.2 [0.25-34.8] ng/mL) (p = 0.046). After adjustment for BMI and gender, hip circumference was associated with log leptin (p = 0.006 with R2 = 0.086) among all subjects. CONCLUSION: Leptin is associated with measures of adiposity, hip circumference in particular, in the non-diabetic state among Saudi subjects. The higher leptin level among diabetics and pre-diabetics is not related to differences in anthropometric measures of obesity.

RT-PCR for the pseudogene-free amplification of the glyceraldehyde-3-phosphate dehydrogenase gene (gapd).

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an enzyme which catalyses the conversion of glyceraldehyde-3-phosphate to 1,3 diphosphoglycerate. It is considered to be constitutively expressed in all cells, and as such the gene for GAPDH (gapd) is commonly used as a benchmark reference in expression studies. However, previous investigations have demonstrated that gapd may show altered gene expression in a number of disease states and under certain experimental conditions, suggesting that results of experiments using gapd as a control should be interpreted with caution. Furthermore, consideration must be given to the potential co-amplification of pseudogenes of gapd during RT-PCR. Here, we describe a method to avoid the amplification of contaminating pseudogenes through the design of primers that bind only to genuine gapd mRNA transcript.

Association between the cholesteryl ester transfer protein TaqI-detectable B polymorphism and low high-density lipoprotein cholesterol concentration in Saudis.

Plasma concentrations of HDL (high-density lipoprotein) cholesterol are low in the Saudi Arabian population. A B polymorphism at the CETP (cholesteryl ester protein transfer) locus that is detectable with the restriction enzyme Taq I is a genetic determinant of the plasma HDL cholesterol concentration. We assessed the relationship between the Taq I B CETP polymorphism and lipid and apolipoprotein concentrations in a study sample of 335 Saudi residents. The Taq I B1 and B2 allele frequencies were 0.54 and 0.46 respectively, similar to those in other populations. HDL cholesterol levels in B2B2 homozygotes were significantly higher than in B1B1 homozygotes [1.01 (0.3) compared with 0.92 (0.2) mmol/l; mean (S.D.); P=0.03]. There was also a significant difference between the B2B2 and B1B1 homozygotes with regard to apolipoprotein AI concentration [123.6 (16.4) compared with 113.7 (13.9) mg/dl; P=0.04]. This genetic variation was independent of metabolic risk factors known to influence HDL cholesterol levels. The allele frequency of the Taq I B CETP polymorphism and its relatively modest impact on HDL cholesterol concentrations argue against an important role for this allele, or for strongly linked loci, in determining the low levels of HDL cholesterol seen in the Saudi population.