Recent studies have revealed that following injuries, ligament tissues such as anterior cruciate ligaments (ACL), release large amounts of matrix metalloproteinases (MMPs). These enzymes have a devastating effect on the healing process of the injured ligaments. Although these enzymes are produced following ligament injuries, because of different healing capacities seen between the medial collateral ligament (MCL) and ACL, we were curious to find if the MMP activity was expressed and modulated differently in these tissues. For this purpose ACL and MCL fibroblasts were seeded on equi-biaxial stretch chambers and were stretched in different levels. The stretched cells were assayed using Zymography, Western Blot and global MMP activity assays. The results showed that within 72 h after injurious stretch, production of 72 kD pro-MMP-2 increased in both ACL and MCL. However, the ACL fibroblasts generated significantly more pro-MMP-2 than the MCL fibroblasts. Furthermore we found in ACL pro-MMP-2 was converted more into active form. With 4-aminophenyl mercuric acetate (APMA) treatment, large amounts of pro-MMP-2 were converted into active form in both. This indicates that there is no significant difference between ACL and MCL fibroblasts in post-translational modification of MMP-2. The fluorescent MMP activity assays revealed that the MMP family activities were higher in the injured ACL fibroblasts than the MCL. Since the MMPs are critically involved in extracellular matrix (ECM) turnover, these findings may explain one of the reasons why the injured ACL hardly repairs. The higher levels of active MMP-2 seen in the ACL injuries may disrupt the delicate balance of ECM remodeling process. These results suggest that the generation and modulation of MMP-2 may be directly involved in the different responses seen in ACL and MCL injuries.

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The interaction mechanism of flavonol myricetin (3,5,7,3',4',5'-hexahydroxyflavone) and human serum albumin (HSA) has been characterized by fluorescence, electronic absorption, and Fourier transform infrared (FT-IR) spectroscopic approaches and the molecular modeling method. The structural characteristics of myricetin and HSA were probed, and their binding affinities were determined under different pH conditions. The results showed that the binding abilities of the drug to protein decreased under lower pH conditions (pH 3.5 and 2.0) due to the alterations of the protein secondary and tertiary structures. The second derivative absorption spectra of myricetin after interacting with the protein showed that the drug existed as an anion form in the binding pocket. The fluorescence emission intensities of the normal and excited-state proton transfer (ESTP) tautomer of myricetin significantly enhanced in the presence of HSA with conspicuous shifts of the emission bands when excited with a wavelength of 370 nm, while the intensity ratios of the normal to ESTP tautomers rose rapidly with the increase of the HSA concentrations under different pH environments. This illustrated that the fluorescence emission of the normal tautomer (S1-S0, non-proton-transferred) predominated due to the interaction of drug and surrounding polar and ionic side chains of amino acid residues in the binding cavity. The similar spectroscopic properties of myricetin-HSA complex at pH 7.4 and 3.5 showed that the drug was located in subdomain IIA of the protein in the vicinity of the single Trp 214 because of the unfolding of the protein domain III in its F state. From the molecular modeling results, the drug-protein complex was stabilized by electrostatic force and hydrogen bonding with the amino acid residue in the binding pocket, which was consistent with the experimental results.

Increasing evidence has confirmed that whole grain oats are effective in regulating hyperlipidemia. Which specific ingredient is crucial remains unclear. This study focused on which components, oat phenolic compounds (OPC)...

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