Identification of palmitate-regulated genes in HepG2 cells by applying microarray analysis

Palmitate is the most abundant saturated fatty acid in the human diet and the major one synthesized de novo. To identify palmitate-regulated genes we performed whole genome mRNA expression profiling by using human hepatoma HepG2 cells. We identified eleven genes which are significantly (single-sided permutational t-test, p<0.05) regulated by low concentration of palmitate (50 microM). We observed a decreased expression of five metallothioneins, and an increased expression of liver expressed plasminogen activator inhibitor-1 protein and insulin-like growth factor II, which play a prominent role in the development of the metabolic syndrome. Comparative promoter analysis in-silico revealed common transcriptional regulation of differentially expressed genes through erythroid kruppel-like factor and members of the zinc binding protein factor family. In conclusion, low physiological palmitate concentrations changed expression of very responsive genes.

Myocardial metabolism and cardiac performance in obesity and insulin resistance

Obesity, insulin resistance, and their frequent complication of type 2 diabetes are risk factors for left ventricular diastolic dysfunction, systolic dysfunction, and clinical heart failure. Although obesity, insulin resistance, and diabetes are risk factors for coronary artery disease, and hence ischemic cardiomyopathy-related heart failure, there is increasing evidence that these three risk factors are implicated in the development of cardiac dysfunction not related to epicardial coronary disease. There are several mechanisms by which this triad may cause cardiac dysfunction, including alterations in myocardial metabolism, which may initially be adaptations but evolve into maladaptive responses over time. Recent advances in our understanding of these mechanisms will aid in the development of novel therapies, including metabolic manipulations that could prevent and treat cardiac dysfunction in patients with obesity, insulin resistance, and diabetes.

Improvements in systemic metabolism, anthropometrics, and left ventricular geometry 3 months after bariatric surgery

BACKGROUND

Several lines of evidence have suggested a link between obesity and heart failure, including chronic inflammation, increased sympathetic tone, and insulin resistance. The goal of this study was to evaluate the changes in systemic metabolism, anthropometrics, and left ventricular (LV) contraction, as well as geometry, in clinically severe obese women after bariatric surgery.

METHODS

Enrollment was offered consecutively to 22 women with clinically severe obesity. Participants underwent abdominal magnetic resonance imaging to quantify the visceral adipose tissue (VAT) area and tissue Doppler imaging echocardiography to measure the LV contractile function. Fasting blood chemistries were drawn to measure inflammatory markers and to calculate insulin sensitivity. All tests were performed before surgery and 3 months postoperatively.

RESULTS

Three months after surgery, a significant increase in insulin sensitivity (mean change +/- SEM 34.0 +/- 10.4, P < .0001) was present. The VAT area had significantly decreased (-66.1 +/- 17.8 cm2, P = .002) and was associated with decreases in body mass index, serum glucose concentrations, and high-sensitivity C-reactive protein levels (r = .61 and P = .005, r = .48 and P = .033, and r = .53 and P = .016, respectively). The LV mass decreased significantly (-3.8 +/- 1.7 g/m(2.7), P = .037), and this decrease was associated with a decrease in glucose concentration (r = .46, P = .041). The LV systolic and diastolic contractile function were normal at baseline, and no change occurred after surgery.

CONCLUSION

The early phase of weight loss after bariatric surgery produces favorable changes in LV geometry, and these are associated with normalization in the glucose metabolism.