Notes

Collagen fiber behavior under biaxial stretch was then studied with the same specimens using small angle light scattering (SALS) under identical biaxial stretch states
Both native and glutaraldehyde modified bovine pericardium were investigated to explore the effects of chemical modification to collagen. Results indicated that collagen fiber and molecular orientation did not change under equibiaxial strain, but were observed to profoundly change under uniaxial stretch. Interestingly, collagen molecular strain initiated only after approximately 15% global tissue strain, potentially due to fiber-level reorganization occurring prior to collagen molecule loading. Glutaraldehyde treatment also did not affect collagen molecular strain behavior, indicating that chemical fixation does not alter intrinsic collagen molecular stiffness. No detectable changes in the angular distribution and D-period strain were found after 80 min of stress relaxation. It can be speculated that other mechanisms may be responsible for the reduction in stress with time under biaxial stretch.

The results of this first study suggest that collagen fiber/molecular kinematics under biaxial stretch are more complex than under uniaxial deformation, and warrant future studies.[Effect of sex-hormone on composition of rat skin surface lipid].The optimum analytical conditions for studying the composition of skin surface lipid were examined by high-performance liquid chromatography equipped with a photo-diode array detector. Optimum conditions were as follows: ULTRON N-C18 (150 x 4 mm) as stationary phase, acetonitrile/tetrahydrofuran/water (55/35/10, V/V) as eluent at the flow rate of 1 ml/min, and column temperature of 40 degrees C. The peaks were detected by monitoring the absorbance at 210 nm. Effect of sex-hormone on composition of skin surface lipids was examined. Gonadectomized Sprague-Dawley rats were injected with either testosterone (50 mg/kg, s.

c.) or estradiol (5 mg/kg, s.c.) for 12 days. Amount of crude lipid from the skin surface was decreased at 8 days after castration; estradiol dosing to castrated rats also decreased the amount. the ordinary squalane cleanser , in ovariectomized rats, testosterone injection increased skin surface lipids. It is recognized that sex-hormone dosing after gonadectomy changes the percentage composition of squalene and cholesterol in male rats, but does not charge them in females.

Determination of morphine in urine by gas chromatography.Ikekawa N, Takayama K, Hosoya E, Oka T.[The effect of ionizing radiation on the interrelationship of collagen molecules Assessment of collagen content in fish skin - development of a flow analysis method for hydroxyproline determination.Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua Diogo This work describes the development of a flow injection method to determine hydroxyproline (HYP), one of collagen's most abundant amino acids. ordinary cleanser is a protein with several applications and high nutritional value. Evaluating the feasibility of using collagen from fish skin over its mammalian source is essential. The determination of HYP requires the pre-treatment and hydrolysis of the fish skin to break down collagen into its amino acids, and the HYP value quantified relates to the collagen content.

The determination was based on the HYP oxidation with permanganate in an alkaline medium and the consequent decrease of colour intensity registered. Under optimal conditions, the developed method enables the determination of the HYP within the dynamic range of 23 to 500 mg L-1, with a limit of detection (LOD) of 2 mg L-1 and a limit of quantification (LOQ) of 23 mg L-1. Different samples were processed, and the digests were analysed by the proposed method and with the conventional procedure with good correlation (relative error < 7%). Moreover, the analyte quantification is performed faster, simpler, and more accurately, with less toxic solutions. The reproducibility of the developed method was also evaluated by calculating the relative standard deviation of the calibration curve slope Guide to collagen characterization for biomaterial studies.The structure and remodeling of collagen in vivo is critical to the pathology and healing of many human diseases, as well as to normal tissue development and regeneration. In addition, collagen matrices in the form of fibers, coatings, and films are used extensively in biomaterial and biomedical applications.

The specific properties of these matrices, both in terms of physical and chemical characteristics, have a direct impact on cellular adhesion, spreading, and proliferation rates, and ultimately on the rate and extent of new extracellular matrix formation in vitro or in vivo. In recent studies, it has also been shown that collagen matrix structure has a major impact on cell and tissue outcomes related to cellular aging and differentiation potential. Collagen structure is complex because of both diversity of source materials, chemistry, and structural hierarchy. With such significant impact of collagen features on biological outcomes, it becomes essential to consider an appropriate set of analytical tools, or guide, so that collagens attained from commercial vendors are characterized in a comparative manner as an integral part of studies focused on biological parameters.
Here's my website: https://en.wikipedia.org/wiki/Squalene