Bioactive behavior

Khan, A.F., Saleem, M., Afzal, A., Ali, A., Khan, A., and Khan, A.R. (2014) Bioactive behavior of silicon substituted calcium phosphate based bioceramics for bone regeneration. Mater. Sci. Eng. C, 35, 245-252. 

These materials have a very good biocompatibility, in addition to an inert and bioactive behavior. The main problem with these carbon materials is their easy wear, which results in the release of black, sharp-edged particles. This may induce either a tattoo effect or the frequent appearance of granuloma as a foreign body reaction with inflammatory cells. This reaction is neither chemical nor physiological, but is a physical and mechanical effect (Oppenheimer effect). The problem has been resolved by the addition of epoxy resins to harden the carbon... 

Singh, J., Dutta, P. K., Dutta, J. et al., 2008. Physiochemical and bioactivity behavior of highly soluble chitosan-L-glutamic acid aerogel derivative. Asian Chitin Journal, 4 9-18. 

Li, X., Shi, J.L., Dong, X.P., Zhang, L.X., Zeng, H.Y., 2008. A mesoporous bioactive glass/ polycaprolactone composite scaffold and its bioactivity behavior. Journal of Biomedical Materials Research Part A 84A, 84—91. 

The bioactive behavior of various glass-ceramics of this type, for example, 46.2 wt% Si02, 25.5 wt%... 

In addition, biomaterials with appropriate three-dimensional geometry (appropriate porous structure) are highly recommended because are able to become osteoinductive (capable of osteogeneis), and can be effective carriers of bone cell seeds. A new way of preparing in situ porous bioactive ceramics with interconnected porosity from a dense bioactive ceramic is presented. To this purpose the binary system wollastonite- tricalcium phosphate is selected, taking into account the different bioactivity behavior of both phases. 

HowevCT, in a number of cases, one of the enantiomers of a drug has been found to act as a blocker of the biological receptor site, thus diminishing the activity of the other enantiomer. Worse, one of the enantiomers may have a completely different, and sometimes toxic, spectrum of activity. This phenomenon is quite general, since nature s receptor sites are handed (Real Life 5-5). Several examples of diffoent bioactive behavior between enantiomers are shown below. 

Chen, J., Zhang, G., Yang, S., et al., 2011. Effects of in situ and physical mixing on mechanical and bioactive behaviors of nano hydroxyapatite-chitosan scaffolds. Journal of Biomaterials Science, Polymer Edition 22 (15), 2097-2106. 

Because of their low immunogenic potential, potential bioactive behavior, capability of interacting with the host s tissue, chemical versatility, and almost unlimited source, starch-based polymers are considered to be ideal materials for tissue engineering (Cunha et al ... 

Although benzofuroxan (Bfx) and furoxan (Fx) were first synthesized over 100 years ago, it was not until the middle of the 20th century that its relevant bioactivities were identified. Bfx s and Fx s relevant biological behaviors convert these systems in one of the most current study heterocycles in medicinal chemistry. Formally, these compounds are 1,2,5-oxadiazole hf-oxide derivatives, specifically Bfx should be named as benzo[l,2-c][l,2,5]oxadiazole 1-oxide and Fx as 1,2,5-oxadiazole 2-oxide, however, the common trivial... 

Neuropeptide S (NPS) is a recently discovered bioactive peptide that has emerged as a new signaling molecule in the complex circuitry that modulates sleep-wakefulness and anxiety-like behavior. The peptide precursor is expressed most prominently in a novel nucleus located in the perilocus coeruleus, a brain structure with well-defined functions in arousal, stress, and anxiety. NPS was also found to induce anxiolytic-like behavior in a battery of four different tests of innate responses to stress. Infusion of NPS potently increases wakefulness and suppresses non-REM (NREM) and REM sleep (Xu et al, 2004). NPS binds to a G-protein-coupled receptor, the NPS receptor, with nanomolar affinity activation of the receptor mobilizes intracellular calcium. The NPS receptor is expressed throughout the brain, particularly in regions relevant to the modulation of sleep and waking, in the tuberomammillary region, lateral hypothalamus, and medial thalamic nuclei. 

A first and apparently straightforward strategy to improve pharmacokinetic behavior of bioactive peptides is to derivatize the N-terminus, the C-terminus, and/or one or more functionalized side chains. Different biological consequences are conceivable depending on the stability and intrinsic activity of the derivative. 

Despite the apparent simplicity of their molecular structure, the metabolism of these agents is chemically so complex, and their routes of bioactivation and inactivation so intimately intertwined, that a detailed and coherent picture of their behavior in the body is not available. The presentation to follow considers first their in vivo de-esterification, and only then the nonen-zymatic and enzymatic mechanisms postulated to be involved. 

Proper protein folding is a concern in the production of a bioactive protein therapeutic, and it is of interest to verify that the conformation of a recombinant protein is the same as the wild-type molecule. Because retention in RPLC depends on the surface hydrophobic contact area, comparable chromatographic behavior of a recombinant protein with that of the wild-type molecule provides evidence of similar 3-D structure.17 38... 

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