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Background: Serum cobalamin (vitamin B12), bound to transcobalamin II, is taken up by the endothelium of the hepatic vasculature via a receptor-mediated membrane transport process. We hypothesized hepatic congestion is associated with elevated serum B12 without hepatocyte necrosis., Methods and Results: Serum B12, aspartate and alanine transaminases, alkaline phosphatase, bilirubin (Bili), and brain natriuretic peptide (BNP) were monitored at the time of admission in 91 hospitalized patients: (a) 38 with decompensated biventricular failure having systemic venous distention, tricuspid regurgitation (TR), and echocardiographic evidence of inferior vena cava dilation and moderate to marked TR; (b) 18 with acute left heart failure having a myocardial infarction, an ischemic cardiomyopathy, or hypertensive heart disease; and (c) 35 without clinical evidence of failure despite myocardial infarction, pericarditis, or atrial arrhythmia. Serum cobalamin (normal 180-600 pg/mL) was elevated with biventricular failure (861.4 +/- 53.0 pg/mL) compared with (P < 0.0001) left heart or no failure, where B12 remained normal. Serum aspartate, alanine, and alkaline phosphatase were normal in each group whereas Bili was increased (1.8 +/- 0.2 mg/dL; P < 0.05) with biventricular failure. Plasma BNP was elevated in each group., Conclusions: Elevated cobalamin and Bili are respective biomarkers of hepatocellular dysfunction and cholestasis in patients having decompensated biventricular failure with systemic venous distention and TR without hepatocyte necrosis vis-à-vis left heart failure or in the absence of clinical failure. Elevated plasma BNP did not distinguish between the presence or absence of systemic venous congestion.

Specific fatty acid alterations have been described in the blood and tissues of cystic fibrosis (CF) patients. The principal alterations include decreased levels of linoleic acid (LA) and docosahexaenoic acid (DHA). We investigated the potential mechanisms of these alterations by studying the cellular uptake of LA and DHA, their distribution among lipid classes, and the metabolism of LA in a human bronchial epithelial cell model of CF. CF (antisense) cells demonstrated decreased levels of LA and DHA compared with wild type (WT, sense) cells expressing normal CFTR. Cellular uptake of LA and DHA was higher in CF cells compared with WT cells at 1 h and 4 h. Subsequent incorporation of LA and DHA into most lipid classes and individual phospholipids was also increased in CF cells. The metabolic conversion of LA to n-6 metabolites, including 18:3n-6 and arachidonic acid, was upregulated in CF cells, indicating increased flux through the n-6 pathway. Supplementing CF cells with DHA inhibited the production of LA metabolites and corrected the n-6 fatty acid defect. In conclusion, the evidence suggests that low LA level in cultured CF cells is due to its increased metabolism, and this increased LA metabolism is corrected by DHA supplementation.

Cystic fibrosis (CF) is associated with fatty acid alterations characterized by low linoleic and docosahexaenoic acid. It is not clear whether these fatty acid alterations are directly linked to cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction or result from nutrient malabsorption. We hypothesized that if fatty acid alterations are a result of CFTR dysfunction, those alterations should be demonstrable in CF cell culture models. Two CF airway epithelial cell lines were used: 16HBE, sense and antisense CFTR cells, and C38/IB3-1 cells. Wild-type (WT) and CF cells were cultured in 10% fetal bovine serum (FBS) or 10% horse serum. Fatty acid levels were analyzed by GC-MS. Culture of both WT and CF cells in FBS resulted in very low linoleic acid levels. When cells were cultured in horse serum containing concentrations of linoleic acid matching those found in human plasma, physiological levels of linoleic acid were obtained and fatty acid alterations characteristic of CF tissues were then evident in CF compared with WT cells. Kinetic studies with radiolabeled linoleic acid demonstrated in CF cells increased conversion to longer and more-desaturated fatty acids such as arachidonic acid. In conclusion, these data demonstrate that CFTR dysfunction is associated with altered fatty acid metabolism in cultured airway epithelial cells.