Hepatic gene expression in morbidly obese women: implications for disease susceptibility.

The objective of this study was to determine the molecular bases of disordered hepatic function and disease susceptibility in obesity. We compared global gene expression in liver biopsies from morbidly obese (MO) women undergoing gastric bypass (GBP) surgery with that of women undergoing ventral hernia repair who had experienced massive weight loss (MWL) following prior GBP. Metabolic and hormonal profiles were examined in MO vs. MWL groups. Additionally, we analyzed individual profiles of hepatic gene expression in liver biopsy specimens obtained from MO and MWL subjects. All patients underwent preoperative metabolic profiling. RNAs were extracted from wedge biopsies of livers from MO and MWL subjects, and analysis of mRNA expression was carried out using Affymetrix HG-U133A microarray gene chips. Genes exhibiting greater than twofold differential expression between MO and MWL subjects were organized according to gene ontology and hierarchical clustering, and expression of key genes exhibiting differential regulation was quantified by real-time-polymerase chain reaction (RT-PCR). We discovered 154 genes to be differentially expressed in livers of MWL and MO subjects. A total of 28 candidate disease susceptibility genes were identified that encoded proteins regulating lipid and energy homeostasis (PLIN, ENO3, ELOVL2, APOF, LEPR, IGFBP1, DDIT4), signal transduction (MAP2K6, SOCS-2), postinflammatory tissue repair (HLA-DQB1, SPP1, P4HA1, LUM), bile acid transport (SULT2A, ABCB11), and metabolism of xenobiotics (GSTT2, CYP1A1). Using gene expression profiling, we have identified novel candidate disease susceptibility genes whose expression is altered in livers of MO subjects. The significance of altered expression of these genes to obesity-related disease is discussed.

A hyperactive pulmonary vasculature in response to chronic mitral regurgitation.

A subset of patients with mitral valve disease has a marked rise in pulmonary vascular resistance (PVR) that is disproportionate to elevations in pulmonary venous pressure. Termed a "hyperactive" pulmonary vasculature, the elevation in PVR falls promptly and dramatically in response to mitral valve replacement. We report a 55-year-old man with progressive, exertional dyspnea of several months' duration who had signs of congestive heart failure (CHF) with moderate mitral valvular regurgitation and aortic stenosis by echocardiographic interrogation. These lesions in combination, together with his CHF and disproportionate elevation in pulmonary artery systolic pressure (90 mm Hg) and PVR (527 dyne x s x cm(-5)), raised the prospect of valvular replacement. There followed a normalization of PVR and marked improvement in his symptoms and signs of CHF in response to pharmacologic management with an ACE inhibitor, loop diuretic, and aldosterone receptor antagonist to negate any further consideration of surgery.