Thermodynamic analysis questions claims of improved cardiac efficiency by dietary fish oil

Thermodynamic study of canned mince meat and fish in metal cans during 30 months storage

Long storage period for the meat and fish cans of 30 months was presented. The provide investigation aims to found thermodynamic stability in mackerel in tomato sauce and finely ground pork minced meat. During the storage period a decrease in pH in two types of cans were seen. pH values for mackerel in tomato sauce and for finely ground pork minced meat cans were measured between 6.2±0.19 to 4.8±0.22 and 5.8 ±0.24 to 3.9±0.17 in the starting to the end of storage, respectively. Determined absorption is used to calculated equilibrium constant, Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS). For mackerel in tomato sauce ΔG exhibit value -8.33±0.07 kJ.mol−1 and for finely ground pork -6.79±0.09 kJ.mol−1. Microscopic examinations were performed and the size of the particles was determined. In measurements in mackerel in tomato sauce the sizes are between 25±0.79 to 62±1.28 μm and for finely ground pork minced meat the particle sizes are between 32±1.12 to 89±2.48 μm in the investigation period. Based on the experiment, both types of canned food are defined as thermodynamically stable after negative Gibbs energies observations, but canned fish is defined as more stable and may have a longer stored.

Understanding Membrane Protein Drug Targets in Computational Perspective

Membrane proteins play crucial physiological roles in vivo and are the major category of drug targets for pharmaceuticals. The research on membrane protein is a significant part in the drug discovery. The biological process is a cycled network, and the membrane protein is a vital hub in the network since most drugs achieve the therapeutic effect via interacting with the membrane protein. In this review, typical membrane protein targets are described, including GPCRs, transporters and ion channels. Also, we conclude network servers and databases that are referring to the drug, drug-target information and their relevant data. Furthermore, we chiefly introduce the development and practice of modern medicines, particularly demonstrating a series of state-of-the-art computational models for the prediction of drug-target interaction containing network-based approach and machine-learningbased approach as well as showing current achievements. Finally, we discuss the prospective orientation of drug repurposing and drug discovery as well as propose some improved framework in bioactivity data, created or improved predicted approaches, alternative understanding approaches of drugs bioactivity and their biological processes.

Experimental and modelling evidence of shortening heat in cardiac muscle

KEY POINTS

Heat associated with muscle shortening has been repeatedly demonstrated in skeletal muscle, but its existence in cardiac muscle remains contentious after five decades of study. By iterating between experiments and computational modelling, we show compelling evidence for the existence of shortening heat in cardiac muscle and reveal, mechanistically, the source of this excess heat. Our results clarify a long-standing uncertainty in the field of cardiac muscle energetics. We provide a revised partitioning of cardiac muscle energy expenditure to include this newly revealed thermal component.

ABSTRACT

When a muscle shortens against an afterload, the heat that it liberates is greater than that produced by the same muscle contracting isometrically at the same level of force. This excess heat is defined as 'shortening heat', and has been repeatedly demonstrated in skeletal muscle but not in cardiac muscle. Given the micro-structural similarities between these two muscle types, and since we imagine that shortening heat is the thermal accompaniment of cross-bridge cycling, we have re-examined this issue. Using our flow-through microcalorimeter, we measured force and heat generated by isolated rat trabeculae undergoing isometric contractions at different muscle lengths and work-loop (shortening) contractions at different afterloads. We simulated these experimental protocols using a thermodynamically constrained model of cross-bridge cycling and probed the mechanisms underpinning shortening heat. Predictions generated by the model were subsequently validated by a further set of experiments. Both our experimental and modelling results show convincing evidence for the existence of shortening heat in cardiac muscle. Its magnitude is inversely related to the afterload or, equivalently, directly related to the extent of shortening. Computational simulations reveal that the heat of shortening arises from the cycling of cross-bridges, and that the rate of ATP hydrolysis is more sensitive to change of muscle length than to change of afterload. Our results clarify a long-standing uncertainty in the field of cardiac muscle energetics.