Familial acquired thrombotic thrombocytopenic purpura: ADAMTS13 inhibitory autoantibodies in identical twins

Thrombotic thrombocytopenic purpura (TTP) either occurs in a congenital form caused by ADAMTS13 gene mutations or it is acquired and most often due to ADAMTS13 inhibitory autoantibodies. In congenital TTP siblings are often affected, while acquired TTP occurs sporadically and familial clustering has not been described so far. We report identical twin sisters suffering from acquired TTP due to immunoglobulin G (IgG) autoantibodies inactivating ADAMTS13, suggesting an important role of hitherto unidentified genetic determinants of ADAMTS13 inhibitor formation. These cases also demonstrate that familial clustering is not sufficient for unambiguously diagnosing hereditary ADAMTS13 deficiency and congenital TTP.     

Ethanol metabolism results in a G2/M cell-cycle arrest in recombinant Hep G2 cells

Previous studies using the Hep G2-based VA cells showed that ethanol metabolism resulted in both cytotoxicity and impaired DNA synthesis, causing reduced accumulation of cells in culture. To further characterize the ethanol oxidation-mediated impairment of DNA synthesis we analyzed the cell-cycle progression of VA cells. These studies showed approximately a 6-fold increase in the percentage of cells in the G2/M phase of the cell cycle after 4 days of ethanol exposure. The G2/M transition requires activity of the cyclin-dependent kinase, Cdc2. Cdc2 is positively regulated by association with cyclin B1, and negatively regulated by phosphorylation of amino acids Thr14 and Tyr15. Immunoblot analysis revealed that ethanol metabolism had little affect on total Cdc2 content in these cells, but resulted in the accumulation of up to 20 times the amount of cyclin B1, indicating that cyclin B1 was available for formation of Cdc2/cyclin B1 complexes. Co-immunoprecipitation revealed that 6 times more Cdc2/cyclin B1 complexes were present in the ethanol-treated cells compared with the controls. Investigation of the phosphorylation state of Cdc2 revealed that ethanol oxidation increased the amount of the phosphorylated inactive form of Cdc2 by approximately 3-fold. Thus, the impairment in cell-cycle progression could not be explained by a lack of cyclin B1, or the ability of Cdc2 and cyclin B1 to associate, but instead resulted, at least in part, from impaired Cdc2 activity. In conclusion, ethanol oxidation by VA cells results in a G2/M cell-cycle arrest, mediated by accumulation of the phosphorylated inactive form of Cdc2.     

Differential coupling of m-cholinoceptors to Gi/Go-proteins in failing human myocardium

Muscarinic acetylcholine receptors (mAChRs) mediate their main cardiac effects via pertussis toxin-sensitive G-proteins. Physiological effects differ considerably between atrium and ventricle, and it is unknown to which extent these differences derive from selective receptor-G-protein coupling or further downstream events. We have characterized specific coupling between mAChRs and Gi/Go-protein isoforms in atrial and ventricular myocardium by agonist-dependent photoaffinity labeling with [(32)P]azidoanilido GTP (aaGTP) and immunoprecipitation in sarcolemmal membranes from terminally failing human hearts. The total amount of mAChRs, as determined by specific binding of [(3)H]QNB, was significantly higher in right-atrial (RA +/- SEM, 959 +/- 68 fmol/mg, n = 4) than in left-ventricular membranes (LV, 582 +/- 53 fmol/mg, n = 6). Standardized immunoblots revealed that Gialpha-2 was the predominant subtype in both regions. A 40-kDa splice variant of Goalpha (Goalpha-1 and/or Goalpha-3) was almost exclusively detectable in RA. Levels of Gialpha-3 and a 39-kDa splice variant of Goalpha (Goalpha-2) were also higher in RA. Basal aaGTP binding was higher in RA than in LV for all Gialpha/Goalpha subtypes. The carbachol (10 micromol/l)-induced increase in aaGTP binding was significantly higher in RA than in LV for Goalpha-1/3 (336 +/- 95% of LV, n = 4) and for Gialpha-3 (211 +/- 83%), lower for Gialpha-2 (42 +/- 5%), and was similar in both regions for Goalpha-2 (130 +/- 62%). The differential coupling of mAChRs in human RA and LV suggests that the initiation of different physiological responses to mAChR stimulation starts with signal sorting at the receptor-G-protein level.     

Assessment of superficial coronary vessel wall deformation and stress: validation of in silico models and human coronary arteries in vivo

Cyclic biomechanical stress at the lumen-intima interface plays a crucial role in the rupture of coronary plaque. We performed a comprehensive assessment of a novel angiography-based method for four-dimensional (4D) dynamic assessment of superficial wall stress (SWS) and deformation with a total of 32 analyses in virtual stenosis models with equal lumen dimensions and 16 analyses in human coronary arteries in vivo. The in silico model analyses demonstrated that the SWS, derived by the proposed global displacement method without knowledge of plaque components or blood pressure, was comparable with the result calculated by traditional finite element method. Cardiac contraction-induced vessel deformation increased SWS. Softer plaque and positive arterial remodeling, associated with a greater plaque burden, showed more variation in mean lumen diameter within the cardiac cycle and resulted in higher SWS. In vivo patient analyses confirmed the accuracy of computed superficial wall deformation. The centerlines predicted by our method at random selected time instant matched well with the actual one in angiograms by Procrustes analysis (scaling: 0.995?±?0.018; dissimilarity: 0.007?±?0.014). Over 50% of the maximum SWS occurred at proximal plaque shoulders. This novel 4D approach could be successfully to predict superficial wall deformation of coronary artery in vivo. The dynamic SWS might be more realistic to evaluate the risk of plaque rupture.     

Squeezing Fact from Fiction about 100% Fruit Juice

Total fruit intake in the United States is ~1 cup equivalent per day, or one-half of the 2010 Dietary Guidelines for Americans recommendation for adults. Two-thirds of the fruit consumed is whole fruit and one-third is 100% juice. The nutritional value of whole fruit, with the exception of fiber and vitamin C, may be retained with appropriate juice production methods and storage conditions. One-hundred percent fruit juice consumption is associated with a number of health benefits, such as improved cardiovascular health and decreased obesity, although some of these and other potential benefits are controversial. Comprehensive analyses of the evidence by the Academy of Nutrition and Dietetics in 2014, the US Dietary Guidelines Advisory Committee in 2010, and the Australian Dietary Guidelines of 2013 concluded that 100% fruit juice is not related to adiposity in children when consumed in appropriate amounts for age and energy needs. However, some reports suggest the consumption of fruit juice contributes to unhealthful outcomes, particularly among children. A dietary modeling study on the best ways to meet the fruit intake shortfall showed that a combination of whole fruit and 100% juice improved dietary density of potassium and vitamin C without significantly increasing total calories. Notably, 100% juice intake was capped at amounts consistent with the 2001 American Pediatric Association guidance. The preponderance of evidence supports the position that 100% fruit juice delivers essential nutrients and phytonutrients, provides year-round access to a variety of fruits, and is a cost-effective way to help people meet fruit recommendations.