Xylooligosaccharide (XO) production was performed from xylan, which was obtained by alkali extraction from cotton stalk, a major agricultural waste in Turkey. Enzymatic hydrolysis was selected to prevent byproduct formation such as xylose and furfural. Xylan was hydrolyzed using a commercial xylanase preparation, and the effects of pH, temperature, hydrolysis period, and substrate and enzyme concentrations on the XO yield and degree of polymerization (DP) were investigated. Cotton stalk contains about 21% xylan, the composition of which was determined as 84% xylose, 7% glucose, and 9% uronic acid after complete acid hydrolysis. XOs in the DP range of 2-7 (X6 approximately X5>X2>X3) were obtained with minor quantities of xylose in all of the hydrolysis conditions used. Although after 24 h of hydrolysis at 40 degrees C, the yield was about 53%, the XO production rate leveled off after 8-24 h of hydrolysis. XO yield was affected by all of the parameters investigated; however, none of them affected the DP of the end product significantly, except the hydrolysis period. Enzyme hydrolysis was maintained by the addition of fresh substrate after 72 h of hydrolysis, indicating the persistence of enzyme activity. The optimal hydrolysis conditions were determined as 40 degrees C, pH 5.4, and 2% xylan. The obtained product was fractionated via ultrafiltration by using 10, 3, and 1 kDa membranes. Complete removal of xylanase and unhydrolyzed xylan was achieved without losing any oligosaccharides having DP 5 or smaller by 10 kDa membrane. After a two-step membrane processing, a permeate containing mostly oligosaccharides was obtained.

The aim of this study was to investigate the effects of Raloxifene (Ral) on degeneration-related changes in osteoarthritis (OA)-like chondrocytes using two- and three-dimensional models. Five-azacytidine (Aza-C) was used to induce OA-like alterations in rat articular chondrocytes and the model was verified at molecular and macrolevels. Chondrocytes were treated with Ral (1, 5 and 10 mu M) for 10 days. Caspase-3 activity, gene expressions of aggrecan, collagen II, alkaline phosphatase (ALP), collagen X, matrix metalloproteinases (MMP-13, MMP-3 and MMP-2), and MMP-13, MMP-3 and MMP-2 protein expressions were studied in two-dimensional model. Matrix deposition and mechanical properties of agarose-chondrocyte discs were evaluated in three-dimensional model. One mu M Ral reduced expression of OA-related genes, decreased apoptosis, and MMP-13 and MMP-3 protein expressions. It also increased aggrecan and collagen II gene expressions relative to untreated OA-like chondrocytes. In three-dimensional model, 1 mu M Ral treatment resulted in increased collagen deposition and improved mechanical properties, although a significant increase for sGAG was not observed. In summation, 1 mu M Ral improved matrix-related activities, whereas dose increment reversed these effects except ALP gene expression and sGAG deposition. These results provide evidence that low-dose Ral has the potential to cease or reduce the matrix degeneration in OA.

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In this study, it was hypothesized that Pluronic F-68 (PLF-68) increases matrix synthesis of osteoarthritis (OA) chondrocytes in addition to its well-documented cell survival effect. To test this hypothesis, rat articular chondrocytes were embedded in agarose discs and were exposed to 5-azacytidine (Aza-C) to induce OA-like alterations. Chondrocytes were then treated with PLF-68 (8 and 12 mg/ml) for 10 days. Aza-C-exposed and PLF-68-untreated chondrocytes and Aza-C-unexposed and PLF-68-untreated chondrocytes were used as negative and positive control groups, respectively. Dynamic hydrostatic pressure (max 0.2 MPa, 0.1 Hz) was applied to discs for 30 min/day (5 days/week). Cell viability, collagen and proteoglycan deposition in discs were determined. Unconfined compression stress relaxation tests were performed to determine peak stress and material parameters of discs--namely spring constants (k (1) and k (2)), damping coefficient (η), instantaneous modulus (E (0)) and relaxed modulus (E (∞)) using Kelvin model to evaluate the functional coherence of the matrix. PLF-68 treatment significantly increased the collagen deposition in discs and viability of OA-like chondrocytes. A dose-dependent increase was also observed for elastic stiffness parameters (k (1), k (2), E (0) and E (∞)). Same positive effect of PLF-68 was not observed for proteoglycan deposition. However, dose-dependent increase in η suggests that PLF-68 treatment resulted with the deposition of functional matrix. This is the first study which reports that PLF-68 has also positive effect on collagen synthesis of OA cells. As a conclusion, our results suggest that PLF-68 has a potential for recovery from OA-like alterations, which should be further analyzed.