This paper is concerned with the dissipativity of theoretical solutions to nonlinear Volterra functional differential equations (VFDEs). At first, we give some generalizations of Halanay's inequality which play an important role in study of dissipativity and stability of differential equations. Then, by applying the generalization of Halanay's inequality, the dissipativity results of VFDEs are obtained, which provides unified theoretical foundation for the dissipativity analysis of systems in ordinary differential equations (ODEs), delay differential equations (DDEs), integro-differential equations (IDEs), Volterra delay-integro-differential equations (VDIDEs) and VFDEs of other type which appear in practice.

Novel injectable biodegradable glycol chitosan hydrogels were developed based on thiolated glycol chitosan (GC-SH) and water soluble oligo(acryloyl carbonate)-b-poly(ethylene glycol)-b-oligo(acryloyl carbonate) (OAC-PEG-OAC) triblock copolymers via Michael-type addition reaction. The rheology measurements showed that robust hydrogels were formed rapidly upon mixing aqueous solutions of GC-SH and OAC-PEG-OAC at remarkably low total polymer concentrations of 1.5-4.5 wt % under physiological conditions. The gelation times (varying from 10 s to 17 min) and storage moduli (100 to 4300 Pa) of hydrogels could be controlled by degrees of substitution (DS) of GC-SH, solution pH, and polymer concentration. These glycol chitosan hydrogels had microporous structures, low swelling and slow hydrolytic degradation (stable for over 6 months) under physiological conditions. Notably, these hydrogels were prone to enzymatic degradation with lysozyme. The multiple acryloyl functional groups of OAC-PEG-OAC allowed facile conjugation with thiol-containing biomolecules prior to gelation endowing hydrogels with specific bioactivity. The preliminary cell culture studies revealed that these glycol chitosan hydrogels were cell non-adhesive while Gly-Arg-Gly-Asp-Cys (GRGDC) peptide modified hydrogels could well support adhesion and growth of both MG63 osteoblast and L929 fibroblast cells. These rapidly in situ forming enzymatically biodegradable hybrid hydrogels have great potentials in the development of injectable cell-specific bioactive extracellular matrices for tissue engineering.

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The present study aimed to investigate kinetic alterations of collagen and elastic fibres and their association with cardiac function in the acute myocardial infarction (AMI) heart. AMI was generated in Sprague-Dawley rats by ligation of the left anterior descending coronary artery. Cardiac function was determined using B-ultrasonography, AMI was verified using histopathology. The kinetics of collagen type I/III and elastic fibre were evaluated using immunohistochemistry and western blotting at 1 week (1 w), 2 weeks (2 w), 3 weeks (3 w) and 4 weeks (4 w) post-AMI. Cardiac function was decreased by 78, 70, 50 and 38% at weeks 1, 2, 3 or 4 post-AMI, respectively, compared with the normal heart. Elastic fibre was decreased gradually, demonstrating alterations of 2, 77, 86 or 97% reduction, respectively, at weeks 1, 2, 3 or 4 in the AMI heart. Collagen I fibre was increased 1.4-, 1.5-, 2.9- or 3.9-fold at weeks 1, 2, 3 or 4 respectively, compared with the normal heart. Similarly, collagen III was increased 1.2-, 1.7-, 2.8- or 3.9-fold, following AMI. Kinetics of increased collagen I/III, in combination with decreased elastic fibre in infarcted area following AMI, provided evidence that compromised cardiac function following AMI was due to graduate wound healing/scar formation in the infarcted zone, increased stiffness and reduced flexibility of the heart.

Mitochondrial dysfunction contributes to the imbalance of cellular homeostasis and the development of diseases, which is regulated by mitochondria‐associated factors. The present review aims to explore the process of the mitochondrial quality control system as a new source of the potential diagnostic biomarkers and/or therapeutic targets for diseases, including mitophagy, mitochondrial dynamics, interactions between mitochondria and other organelles (lipid droplets, endoplasmic reticulum, endosomes, and lysosomes), as well as the regulation and posttranscriptional modifications of mitochondrial DNA/RNA (mtDNA/mtRNA). The direct and indirect influencing factors were especially illustrated in understanding the interactions among regulators of mitochondrial dynamics. In addition, mtDNA/mtRNAs and proteomic profiles of mitochondria in various lung diseases were also discussed as an example. Thus, alternations of mitochondria‐associated regulators can be a new category of biomarkers and targets for disease diagnosis and therapy.