Degradation matrix

Cl. Cajot, J. F., Schleuning, W. D., Medcalf, R. L., Bamat, J., Tetuz, J., Libermann, L., and Sordat, B., Mouse L-cells expressing human prourokinase-type plasminogen activator Effects on extracellular matrix degradation and invasion. J. Cell. Biol. 109, 915-925 (1989). 

To further extend the utility of structural methods, researchers compare solid state X-ray crystallographic and solution-state NMR structures to define important differences. For instance, the Bertini group has studied the enzyme matrix metalloproteinase 12 (MMP12), in the presence of its inhibitors. Matrix metalloproteinases (MMPs) are involved in extracellular matrix degradation, a fundamental step in tissue remodeling and repair. There are a great variety of enzymes of this type, the one studied here is one of many found in humans. Most MMPs have three domains (1) a prodomain that is removed... 

Effect of matrix degradation on demineralization during formation of incipient lesions... 

Effect of matrix degradation on the rate of demineralization of incipient erosive lesions in root dentin. Specimens were subjected to daily alternating incubations with HAc pH 5.0 (V,Y) or pH 5.5 ( , ) and either collagenase (TM) or buffer (V,ni (n=5). Values represent mean SD. Levels of significance were calculated according to Student s t test. P<0,05, P<0,01 vs. buffer-treatment. 

In a parallel preliminary experiment, hypochlorite instead of colla-genase was employed for matrix degradation. After hypochlorite treatment, tubules in sound dentin beneath the lesions contained material positive for PAS- and Richardson s stains, which was not observed after the buffer- and collagenase treatments. The bacterial degradation of the organic matrix was, therefore, simulated enzymatically. 

In conclusion, evidence has been gathered for a role of the Maillard reaction in caries. This reaction can cause inhibition of matrix degradation, which in turn inhibits lesion demineralization. Further research is needed to elucidate the pathways and the importance of this reaction in in vivo caries pathology. 

Gowen, M., Lazner, F., Dodds, R., Kapadia, R., Felid, J., Tavaria, M., Bertoncello, L, Drake, F., Zavarselk, S., Tillis, L, Hertzog, P., Debouck, C., and Kola, I. (1999) Cathepsin K Knockout Mice Develop Osteopetrosis Due to a Deficit in Matrix Degradation but not Deminerali zation. Journal of Bone and Mineral Research 14, 1654-63. 

To optimize the applicability of the electrothermal vaporization technique, the most critical requirement is the design of the sample transport mechanism. The sample must be fully vaporized without any decomposition, after desolvation and matrix degradation, and transferred into the plasma. Condensation on the vessel walls or tubing must be avoided and the flow must be slow enough for elements to be atomized efficiently in the plasma itself. A commercial electrothermal vaporizer should provide flexibility and allow the necessary sample pretreatment to introduce a clean sample into the plasma. Several commercial systems are now available, primarily for the newer technique of inductively coupled plasma mass spectroscopy. These are often extremely expensive, so home built or cheaper systems may initially seem attractive. However, the cost of any software and hardware interfacing to couple to the existing instrument should not be underestimated. 

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