Collagen is the oldest and most abundant extracellular matrix protein that has found many applications in food, cosmetic, pharmaceutical, and biomedical industries First, an overview of the family of collagens and their respective structures, conformation, and biosynthesis is provided The advances and shortfalls of various collagen preparations (eg, mammalian/marine extracted collagen, cell-produced collagens, recombinant collagens, and collagen-like peptides) and crosslinking technologies (eg, chemical, physical, and biological) are then critically discussed Subsequently, an array of structural, thermal, mechanical, biochemical, and biological assays is examined, which are developed to analyze and characterize collagenous structures Lastly, a comprehensive review is provided on how advances in engineering, chemistry, and biology have enabled the development of bioactive, 3D structures (eg, tissue grafts, biomaterials, cell-assembled tissue equivalents) that closely imitate native supramolecular assemblies and have the capacity to deliver in a localized and sustained manner viable cell populations and/or bioactive/therapeutic molecules Clearly, collagens have a long history in both evolution and biotechnology and continue to offer both challenges and exciting opportunities in regenerative medicine as nature's biomaterial of choice

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The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development

Tubulointerstitial disease, a prominent phenomenon in diabetic nephropathy, correlates with decline in renal function. The underlying pathogenic link between chronic hyperglycemia and the development of tubulointerstitial injury has not been fully elucidated, but myofibroblast formation represents a key step in the development of tubulointerstitial fibrosis. RAGE, the receptor for advanced glycation end products (AGEs), induces the expression of TGF-beta and other cytokines that are proposed to mediate the transdifferentiation of epithelial cells to form myofibroblasts. Here we report specific binding of (125)I-AGE-BSA to cell membranes prepared from a rat proximal tubule cell line and show that the binding site was RAGE. AGE exposure induced dose-dependent epithelial-myofibroblast transdifferentiation determined by morphological changes, de novo alpha smooth-muscle actin expression, and loss of epithelial E-cadherin staining. These effects could be blocked with neutralizing Ab's to RAGE or to TGF-beta. Transdifferentiation was also apparent in the proximal tubules of diabetic rats and in a renal biopsy from a patient with type 1 diabetes. The AGE cross-link breaker, phenyl-4,5-dimethylthiazolium bromide (ALT 711) reduced transdifferentiation in diabetic rats in association with reduced tubular AGE and TGF-beta expression. This study provides a novel mechanism to explain the development of tubulointerstitial disease in diabetic nephropathy and provides a new treatment target.

/pdf/advanced-glycation-end-products-cause-epithelial-1crh1vffo2.pdf

Advanced glycation end products cause epithelial-myofibroblast transdifferentiation via the receptor for advanced glycation end products (RAGE)

https://sites.ualberta.ca/~huludag/2009-2011/attachments/Xiong%20et%20al%202008.pdf

Biodegradable amphiphilic poly(ethylene oxide)-block-polyesters with grafted polyamines as supramolecular nanocarriers for efficient siRNA delivery

Several variables (kind of filter paper, amount of sample, antioxidant addition, stability of the spectrophotometric measurement, and handling and storage of samples) were found to influence 2-thiobarbituric acid (TBA) values in dark chicken meat when an acid aqueous extraction method with derivative spectrophotometry was used. Filter papers with larger pore diameter or increasing sample weight led to lower TBA values. After incubation of reaction mixtures at 70 degrees C and ice-cooling, tempering for 45 min at room temperature was necessary to stabilize the spectrophotometric measurement. Furthermore, addition of butylated hydroxytoluene (BHT) and ethylenediaminetetraacetic acid disodium salt (EDTA) in the early steps of the method prevented artifactual formation of TBA reactive substances during analysis. Vacuum packaging and storage of samples at -20 degrees C were useful to avoid sample oxidation. The method finally proposed has a coefficient of variation of 3.81 or 4.13% for raw or cooked samples, respectively.

Measurement of 2-thiobarbituric acid values in dark chicken meat through derivative spectrophotometry: influence of various parameters.

The kinetics of the reactions of amino acids with stabilized diarylcarbenium ions (Ar2CH+) have been studied photometrically in aqueous solution at variable pH. In the range of 10.5 < pH < 12, the amino acids react much faster than the competing nucleophiles hydroxide and water. Though the pKaH values of the amino acids vary by almost four units, the nucleophilic reactivities of all primary amino groups differ by less than a factor of 4. The secondary amino group of proline is 102 times more reactive, and the thiolate site in cysteine exceeds the reactivities of the primary amino groups by a factor of 104. Nucleophilicity parameters N as defined by the correlation log k20 °C = s(N + E) have been determined in order to include amino acids into the most comprehensive nucleophilicity scales presently available, which provide a direct comparison of n-, π-, and σ-nucleophiles.

Gérard Tainturier

Papers

The Quantification of Protein Amino Groups by the Trinitrobenzenesulfonic Acid Method: A Reexamination