Vivo Characterization Techniques

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Flow rate Inhaled volume Breath hold 

Figurs 6 Schematic illustration of the application of pharmacokinetics and the charcoal block method to the estimation of lung deposition. (A) Use of urine collection. (B) Use of plasma collection. (From Ref. 24.) 

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Milne et al. [154] have developed stereotactically guided laser thermotherapy for breast cancer in situ measurements. They determine the temperature field within the breast to highlight potential tumors. A review paper by Tromberg et al. [155] discusses the noninvasive in vivo characterization of breast cancer tumors using photon migration spectroscopy. They compare the use of this technique with straightforward NIR spectroscopy. 

These multicomponent lipidic formulations are evaluated and characterized using diverse in vitro, ex vivo, and in vivo procedures. A number of techniques have been employed to characterize the SNEDDS and to determine the feasibihty of their formulation process (Singh et al., 2(X)9). Table 4.5 represents different parameters employed for in vitro, in situ, ex vivo, and in vivo characterization of the SNEDDS. 

Cell culture is a powerful in vitro characterization technique to optimize the properties of a biomaterial for in vivo biomedical use by conversely revealing potential sources of cytotoxicity. A comprehensive literature survey of the range of cell types cultured on porous silicon is given, together with a discussion of how surface chemistry, topography, and porosity gradients affect cell behavior. 

However, one might take the time to think back and to ask if the extensive use of such techniques might not have failed to characterize important lead compounds from plants, and especially medicinal plants. As a matter of fact, a molecule inactive in vitro might, after metabolic transformation in vivo, be effective in abrogating metastasis. The opposite is true, and promising in vitro results have often led to disappointing clinical trials. 

It should be noted however that it is almost impossible to predict fully the in vivo dissolution rate due to the many factors involved, of which several have not yet been completely characterized. The introduction of new study techniques to directly follow drug dissolution in vivo in the human intestine should therefore be of importance [30, 31]. For example, in vivo dissolution studies discriminated between the dissolution rates of the two different particle sizes of spironolactone, based on the intestinal perfusate samples. In addition, dissolution rates of carba-mazepine obtained in vitro were significantly slower than the direct in vivo measurements obtained using the perfusion method. The higher in vivo dissolution rate was probably due to the efficient sink conditions provided by the high permeability of carbamazepine [30, 31]. 

It should be emphasized that the nature of all presented protocols is very general and, thus, their application for a comprehensive characterization of your favorite multiprotein complex (YFMPC) in yeast might require only minor modifications. The logical sequence of all required steps is schematically shown in Fig. 2.1. The initial large-scale Ni affinity isolation of eIF3 followed by mass spectrometry (MS) of its subunit composition has already been described (Asano et al, 2002), and methods for identification of protein-protein interactions such as yeast two-hybrid (Y2H) and in vitro glutathione-S-transferase (GST) pull-down analysis are presented in volume 429. This chapter focuses on a description of the small-scale one-step in vivo affinity purification techniques that were used to determine the effects of deletions and... 

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