Reconstitution Behavior

The reconstitution behavior of porous particles (their so-called instant properties ) can be explained by the fact that the solvent has to penetrate first into the pores of the particles in order to loosen contact forces by, for example, dissolving contact bridges formed by crystals or amorphous material between primary particles (Pfalzer et al., 1973 Schubert, 1975) or by reducing inter-particulate van der Waals forces. The penetration time of the liquid into a porous spray-dried particle with diameter d (wetting time) is given by the well-known Washburn equation (Washburn, 1921 Schubert, 1990)  

The dissolving and dispersing behavior of complexly formulated particles has to be measured in laboratory devices either by optical particle analysis, or by chemical analysis of dissolved matter within the solution or suspension. For that purpose, the spray particles are positioned in baskets within stirred containers, and the light extinction is measured in the suspension or the concentration of dissolved chemical species is recorded versus time (Schubert, 1990 Hogekamp and Pohl, 2004). Similar systems are applied to assess the release functions of pharmaceuticals (Martin and Leuenberger, 2002 Schultz and Kleinebudde, 1997). 

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Thus three lines of evidence define the rapidly dissociating receptor as the LR complex. Conditions known to uncouple R from G--first, guanine nucleotide and second, pertussis toxin—produce LR third, reconstitution of G protein restores receptor affinity, sensitivity to guanine nucleotide, and effector activation. In this sense, the ligand and binding behavior of this system is analogous to that of the beta-adrenergic receptor, where the LR and LRG complexes have already been studied with purified proteins and reconstituted membrane preparations (2,i0). 

Biochemical studies with purified preparations incorporated into liposomes have also been performed [32,33,96-98]. Reconstituted receptors from skeletal muscle bound DHPs, PAAs and diltiazem with high affinity and in a 1 1 1 stoichiometry [97], In general, the reconstituted proteins exhibit the characteristic pharmacological properties expected for these channels. In recent studies, our laboratory has reconstituted partially purified channels into liposomes containing the Ca -sensitive fluorescent dye, fluo-3 [33,96]. These channels exhibit Ca influx that is sensitive to activation by Ca channel activators and inhibitors with affinities similar to those observed in intact cells, and the Ca influx is dependent on the establishment of a gradient in the presence of valinomycin [132]. This assay provides a convenient and rapid approach to obtaining a macroscopic picture of the activity of the channels under different conditions, while the more complex studies in lipid bilayers provide a more complete analysis of the single channel behavior. 

Fig. 10. A. Acetic acid-urea-triton-X-100 polyacrylamide gel electrophoresis [15] of the histones used to reconstitute 208-12 nucleosome arrays consisting of recombinant H2A.Z (lane 2) or recombinant H2A.1 (lane 3). Lanes 1 and 4 respectively are chicken erythrocyte and calf thymus histones used as markers [42]. B. Ionic strength (NaCl concentration) dependence of the average sedimentation coelRcient (s2o,w) of reconstituted 208-12 nucleosome arrays containing either H2A.1 (O) or H2A.Z ( ) [42]. The dotted line represents the behavior of a 208-12 complex reconstituted with chicken erythrocyte histones [406]. [Reproduced from Abbott D.W. et al. (2001) I. Biol. Chem. 276, 41945-41949, with permission from The American Society for Biochemistry and Molecular Biology.]...

The nickel proteins and the native iron globins show the same behavior in regard to fifth-ligand photodissociation but for totally different reasons. Heme proteins and other metal-reconstituted heme proteins have been investigated by transient absorption spectroscopy (49-53) and transient Raman spectroscopy (16,54-62). In none of the Fe proteins is loss of the histidine ligand observed even on a picosecond timescale. Soret excitation of carbonmonoxy and oxy Hb and Mb photolyzes CO or O2, but not the histidine fifth ligand. 

Peg Interferon Alfa 2b (PEG-Intron) [Antiviral/ Immunomodulator] WARNING Can cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disord s. Monitor pts closely Uses Rx Hep C Action Immune modulation Dose 1 mcg/kg/wk SQ 1.5 mcg/kg/wk combined w/ ribavirin Caution [C, X if used w/ ribavirin /-] w/ Hx psychiatric Contra Autoimmune H, decompensated Uvct Dz, hemoglobinopathy Disp Vials 50, 80, 120, 150 mcg/0.5 mL Redipen 50, 80,120,150 mcg/5 mL reconstitute w/ 0.7 mL w/ sterile water SE D ession, insomnia, suicidal behavior, GI upset, neutropenia, thrombocytopenia, alopecia, pruritus Interactions t Myelosuppression W/ antineoplastics t effects OF doxorubicin, theophylline t neurotox W7 vinblastine EMS See Peg Interf on Alfa-2a may cause flu-like Sxs... 

Finally, freeze-dried, AmB-loaded PEBPBLA micelles easily dissolved within a few seconds in aqueous solutions. This contrasts with the behavior of PEKBbA and AmB, both of which are insoluble when directly placed in water. TEM reveals that the PtRBItA micelles remain intact, and the size distribution conLrms the absence of any secondary aggregation that may have resulted from the freeze-drying and reconstitution processes. Further, the resultant AmB-loaded PEO-bPBLA micelles cause no hemolysis atflQ/mL, indicating that AmB is still present inside the polymeric micelles. An AmB level of 5.0 mg/mL was obtained this is 10,000 times the solubility... 

Multiplicity of Cytochrome P450, Purification, and Reconstitution of Cytochrome P450 Activity. Even before appreciable purification of CYP had been accomplished, it was apparent from indirect evidence that mammalian liver cells contained more than one CYP enzyme. Subsequent direct evidence on the multiplicity of CYPs included the separation and purification of CYP isozymes, distinguished from each other by chromatographic behavior, immunologic specificity, and/or substrate specificity after reconstitution and separation of distinct polypeptides by sodium... 

Transport by facilitated diffusion A large number of molecules and ions were shown to permeate membranes considerably faster than expected from their lipid-water partitioning behavior. This led to the recognition of additional transport mechanisms. Systematic investigations of permeability rates in membranes, reconstituted membranes, and membrane models as functions of the temperature of the nature and concentration of the permeant in the absence and in the presence of additives, suggested three different facilitated passive transport mechanisms ... 

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