Bondhurst1337

Excess intake of 'free sugars' is a key predictor of chronic disease, obesity, and dental ill health. Given the importance of determining modifiable predictors of free sugar-related dietary behaviors, we applied the integrated behavior change model to predict free sugar limiting behaviors. The model includes constructs representing 'reasoned' or deliberative processes that lead to action (e.g., social cognition constructs, intentions), and constructs representing 'non-conscious' or implicit processes (e.g., implicit attitudes, behavioral automaticity) as predictors of behavior. Undergraduate students (N = 205) completed measures of autonomous and controlled motivation, the theory of planned behavior (TPB) measures of explicit attitude, subjective norms, perceived behavioral control (PBC), and intentions, past behavior, implicit attitude, and behavioral automaticity at an initial point in time, and free sugar limiting behavior and behavioral automaticity two weeks later. A Bayesian structural equation model indicated that explicit attitude, subjective norms, and PBC predicted behavior via intention. Autonomous motivation predicted behavior indirectly through all TPB variables, while controlled motivation predicted behavior only via subjective norms. Implicit attitudes and behavioral automaticity predicted behavior directly and independently. Past behavior predicted behavior directly and indirectly through behavioral automaticity and intentions, but not implicit attitudes. Current findings suggest pervasive effects of constructs representing both reasoned and non-conscious processes and signpost potential targets for behavioral interventions aimed at minimizing free sugar consumption. In this work, we revisit the scaling analysis and commonly accepted conditions for the validity of the standard, reverse and total quasi-steady-state approximations through the lens of dimensional Tikhonov-Fenichel parameters and their respective critical manifolds. By combining Tikhonov-Fenichel parameters with scaling analysis and energy methods, we derive improved upper bounds on the approximation error for the standard, reverse and total quasi-steady-state approximations. Furthermore, previous analyses suggest that the reverse quasi-steady-state approximation is only valid when initial enzyme concentrations greatly exceed initial substrate concentrations. Thapsigargin ic50 However, our results indicate that this approximation can be valid when initial enzyme and substrate concentrations are of equal magnitude. Using energy methods, we find that the condition for the validity of the reverse quasi-steady-state approximation is far less restrictive than was previously assumed, and we derive a new "small" parameter that determines the validity of this approximation. In doing so, we extend the established domain of validity for the reverse quasi-steady-state approximation. Consequently, this opens up the possibility of utilizing the reverse quasi-steady-state approximation to model enzyme catalyzed reactions and estimate kinetic parameters in enzymatic assays at much lower enzyme to substrate ratios than was previously thought. Moreover, we show for the first time that the critical manifold of the reverse quasi-steady-state approximation contains a singular point where normal hyperbolicity is lost. Associated with this singularity is a transcritical bifurcation, and the corresponding normal form of this bifurcation is recovered through scaling analysis. BACKGROUND Cardiovascular diseases (CVDs), with highest mortality and morbidity rates, are the major cause of death in the world. Due to the limited information on heart tissue changes, mediated by hypercholesterolemia, we planned to investigate molecular mechanisms of endoplasmic reticulum (ER) stress and related cell death in high cholesterol fed rabbit model and possible beneficial effects of α-tocopherol. METHODS Molecular changes in rabbit heart tissue and cultured cardiomyocytes (H9c2 cells) were measured by western blotting, qRT-PCR, immunflouresence and flow cytometry experiments. Histological modifications were assessed by light and electron microscopes, while degradation of mitochondria was quantified through confocal microscope. RESULTS Feeding rabbits 2% cholesterol diet for 8 weeks and treatment of cultured cardiomyocytes with 10 μg/mL cholesterol for 3 h induced excessive autophagic activity via IRE1/JNK pathway. While no change in ER-associated degradation (ERAD) and apoptotic cell death were determined, electron and confocal microscopy analyses in cholesterol supplemented rabbits revealed significant parameters of autophagic cell death, including cytoplasmic autophagosomes, autolysosomes and organelle loss in juxtanuclear area as well as mitochondria engulfment by autophagosome. Either inhibition of ER stress or JNK in cultured cardiomyocytes or α-tocopherol supplementation in rabbits could counteract the effects of cholesterol. CONCLUSION Our findings underline the essential role of hypercholesterolemia in stimulating IRE1/JNK branch of ER stress response which then leads to autophagic cell death in heart tissue. Results also showed α-tocopherol as a promising regulator of autophagic cell death in cardiomyocytes. Polycyclic Aromatic Hydrocarbons (PAHs) form a family of compounds that are generally found in complex mixtures. PAHs can lead to the development of carcinogenesis. The Toxicity Equivalent Factor (TEF) approach has been suggested for estimating the toxicity of PAHs, however, due to the relative weakness of available data, TEF have not been applied for the risk characterization of PAHs as food contaminants in Europe. The determination of new TEFs for a large number of PAHs could overcome some limitations of the current method and improve cancer risk assessment. The present investigation aimed at deriving new TEFs for PAHs, based on their genotoxic effect measured in vitro and analyzed with mathematical models. For this purpose, we used a genotoxicity assay (γH2AX) with three human cell lines to analyze the genotoxic properties of 27 selected PAHs after 24 h treatment. For 11 compounds, we did not detect any genotoxic potential. For the remaining 16 PAHs, the concentration-response for genotoxic effect was modelled with the Hill equation; equivalency between PAHs at low dose was assessed by applying constraints to the model parameters.