The use of differential scanning calorimetry to study the effects of gentamycin on fibrous collageneous membranes (original) (raw)
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In vitro studies on aminoglycosides permeation and resorption in porcine skin as a model membrane
Journal of Veterinary Animal Sciences, 2012
The in vitro study of drug skin permeability plays an essential role in the selection of drugs for the development of transdermal dosage forms. Therefore, the objective of present study was to state the dermal penetration, permeation and absorption of topically applied substances (Gentamicin and Polymyxin B sulphate). Skin samples of the ear and umbilical region of porcine were used in the experiments. At the beginning of the experiment, 500 µL of drug gel formulation was placed on the external side of the skin. After elapsed times of 30, 60, 90 and 120 min, 1.0 mL of the receiving solution was withdrawn and replaced with an equal volume of fresh buffer. The concentrations of each compound in the receiver medium were determined by high-performance liquid chromatography (HPLC). The results of the present study showed that all samples were under the detection limit. In conclusion, the systemic absorption for gentamicin and polymyxin B sulphate is poor when used topically.
Two subsystems of meniscal collagen and their different thermal stabilities
Doklady Biochemistry and Biophysics, 2012
Collagen is the main structural protein of connec tive tissues fulfilling a variety of mechanical functions, including sustenance, support, extension, compres sion, and shear . The structure of the stroma of these tissues depends on how the rod shaped mole cules with a triple helical conformation interact with other macromolecules, how they are packed in fibers, and, in turn, how these fibers are mutually arranged. Manifold structures of this stroma provide for a diver sity of the fulfilled functions.
Decreased thermal stability of collagens containing analogs of proline or lysine
Archives of Biochemistry and Biophysics, 1974
Fibroblasts were incubated with analogs of proline or lysine and the thermal stability of procollagen molecules containing the analogs was investigated using pepsin digestion at different temperatures as an enzymatic probe of conformation. The procollagens containing either 4-cis-hydroxy-L-proline, 3,4-dehydroproline, or 4,5-trans-dehydrolysine were less stable than normal procollagen and these abnormal collagens were largely in a non-triplehelical conformation within the cells at 37°C. These results support the idea that procollagen molecules which are not in a triple-helical conformation are not secreted at a normal rate. Procollagens containing both 4,5-trans-dehydrolysine and a proline analog were much less stable than molecules containing a single type of analog. This result suggests that simultaneous administration of both types of analogs may have a greater effect on collagen accumulation in whole-animal experiments than administration of a single analog.
Clinical materials, 1994
Experiments were carried out to study the effect on the degree of crosslinking of: (a) short term (1 or 5 min) high (50 degrees C) temperature glutaraldehyde (GA) fixation of native collagen membrane, (b) a combination of GA presoaking at low temperature [0 degree C or room temperature (rt)] followed by short time (< 3 min) heating of synthetic collagen fleece in a multilayer diffusion model. As a measure for the degree of crosslinking the shrinkage temperature (Ts) was determined. Short time (1 or 5 min) high temperature (50 degrees C) fixation using 0.1% GA solution caused the shrinkage temperature to increase to 80% and 93% respectively, of the maximum attainable Ts employing GA crosslinking (ca 91 degrees C). Fixation with 0.01% GA for 5 min at 50 degrees C appeared equally as effective as 1 min with 0.1% GA. Although an elevated fixation temperature (from rt to 45 degrees C) was found to produce a substantial increase in Ts of the collagen sheets, a homogeneous distribution ...
Biomaterials, 1987
Diffusion of angiotensin II, albumin and aldolase was studied through collagen membranes with swelling ratios between 4 and 15. The diffusion coefficient was measured from the time-lag for the onset of steadystate flux through the membrane. Binding of macromolecules to collagen was evaluated from the results of sorption studies conducted as a function of macromolecular concentration. Results presented indicate that the diffusion of macromolecules through collagen membranes is slowed by electrostatic and hydrogen bonding between individual macromolecular chains and collagen. The extent of adsorption is increased as the molecular weight of the diffusant increases. Diffusion of water soluble macromolecules through collagen occurs rapidly, suggesting that diffusion occurs through water filled channels as opposed to between collagen molecules. The results of these studies are useful in understanding diffusion through connective tissues and in the design of drug delivery systems based on collagen.