Degradation pattern

Bis(tributyltin) oxide is known to break down to inorganic tin under UV irradiation in laboratory conditions (509, 510), and the decomposition may be accelerated by absorbing the organotin compound on a cel-lulosic matrix (511). As bis(tributyltin) oxide is known to react rapidly with carbon dioxide (atmospheric, or trapped in various cellulosic materials, such as cotton or wood) (512), to form bis(tributyltin) carbonate, (BusSnO)2CO, the observed UV degradation pattern may be rationalized in terms of more-ready breakdown of the carbonate than of the oxide, due to the presence of the carbonyl chromophore. The half-life of bis(tributyltin) oxide in pond water has recently been given as 16 days (513). Diorganotin compounds have also been shown to decompose to inorganic tin under UV irradiation (514, 515). 

Wegener, C., Bartling, S., Olsen, O., Thomsen, K.K., Bahlow, R. and von Wettstein, D. Differences in cell wall degradation patterns by Erwinia carotovora pectate lyase isoenzymes. Submitted to Protoplasma. 

As mentioned previously, most agrochemicals do not exhibit linear degradation patterns. As a result, Hamaker proposed another variation of the linear-fit equation that allows better description of nonlinear data sets ... 

Figure 17.1 Generalized degradation pattern for diflubenzuron. Diflubenzuron (A) degrades initially to 2,6-difluorobenzoic acid (B) and 4-chlorophenylurea (C). 2,6-Difluorobenzoic acid (B) degrades to 2,6-difluorobenzamide (D) and 4-chlorophenylurea (C) degrades to 4-chloroaniline (E).

A full understanding of chemical ecology must therefore include not only the characterization of chemically unique signals but also their environmental dispersal and degradation patterns that are an intrinsic part of chemosensory transduction and signal processing and lead to the appropriate behavioral responses. One of the most difficult tasks has been to measure the natural stimulus dispersal patterns at a spatial and temporal resolution relevant to the animal. 

A protein whose degradation pattern is even more difficult to explain is recombinant human interleukin 2 (rhIL-2), a lymphokine produced by T-cells and being developed as an immunomodulator. This protein, which consists... 

Further differentiation was obtained using the chromophoric cel-looligodextrins and a rapid and sensitive HPLC analysis of the reaction products (1). Specific degradation patterns were obtained for several enzymes such as those from Clostridium cloned in E. coli (Fig. 2). 

Asano, M.,Fukuzaki,H., Yoshida, M., Kumakura, M., Mashimo, T., Yuasa, H., Imai, K., Yamanaka, H., Kawaharada, U., Suzuki, K. (1991). In vivo controlled release of a luteinizing hormone-releasing hormone agonist from poly(DL-lactic acid) formulation of varying degradation pattern. Int. J. Pharm., 67,61-11. 

The method will be used in the manufacturing facility for the release of both drug substance and drug product. However, if there are any changes in the manufacturing process that have the potential to change the degradation pattern... 

T ine structural studies on woody cell walls attacked by ectoenzymes of fungi in situ are numerous (cf. 1,2). In contrast, investigations on the selective degradation of cell walls by enzymes isolated from fungi are few. Jutte and Wardrop (3) attempted the use of crude commercial cellu-lase preparations to determine the degradation pattern of Valonia cellulose and beechwood fibers. Similar use of commercial preparations of enzymes was made by Reis and Roland (4) to evaluate the nature of diverse cell walls and to show the distribution of polysaccharides. An endo-/ -l,4-xylanase with specific xylanolytic activities was isolated from a commercial cellulase preparation using chromatographic methods and... 

Avicelases or Cellobiohydrolase C - - Mannanase. The action of mannanase on delignified sprucewood holocelluloses that were treated with avicelase 1, avicelase 2, or cellobiohydrolase C for 48 hr gave similar degradation patterns. The rate of total degradation increased rapidly when the mannanase was added the rate was most pronounced in the case of avicelase 1 (Figure 4). 

The degradation pattern of an organic molecule due to autoxidation is often a complex process, and is one of the reasons why molecular oxygen is seldom the preferred reagent of the synthetic organic chemist. Now that the main features of the autoxidation mechanism have been stated, it is appropriate to analyze the fate of the reactive species afforded by the reaction, in order to understand the whole degradation profile. 

The degradation pattern of alkenes has been amply illustrated, particularly for tetrazepam and cholesterol. In addition to the activation of the a-sp3 carbon atom, alkenes can give epoxidation and polymerization... 

The first step of the design of stress experiments should be to examine the molecular formula of the test compound. Does the structure resemble substances for which a degradation pattern is already known Does it contain easy oxidizable functional groups Do tautomers exist, that can be more sensitive to oxidants Can pH affect the sensitivity, because prototropic equilibria can generate easily oxidizable species Are potential degradation impurities available Time spent in answering these questions and in collecting literature data is never lost. 

Hansen J, Bundgaard H. Studies on the stability of corticosteroids Y. The degradation pattern of hydrocortisone in aqueous solution. Int J Pharmaol 1980 6 307-319. 

Figge K, Klahn J, Koch J. 1983. Testing of chemicals by evaluation of their distribution and degradation patterns in an environmental standard system. Regul Toxicol Pharmacol 3 199-215. 

In bulk erosion, the entire area of polymer matrix is subject to chemical or enzymatic reactions, thus erosion occurs homogeneously throughout the entire matrix Accordingly, the degradation pattern is sometimes termed homogeneous erosion. 

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