Soy protein may alleviate osteoarthritis symptoms

Alternative and complementary therapeutic approaches, such as the use of a wide array of herbal, nutritional, and physical manipulations, are becoming popular for relieving symptoms of osteoarthritis (OA). The present study evaluated the efficacy of soy protein (SP) supplementation in relieving the pain and discomfort associated with OA. One hundred and thirty-five free-living individuals (64 men and 71 women) with diagnosed OA or with self-reported chronic knee joint pain not attributed to injury or rheumatoid arthritis were recruited for this double-blind, placebo-controlled, parallel design study. Study participants were assigned randomly to consume 40 g of either supplemental SP or milk-based protein (MP) daily for 3 months. Pain, knee range of motion, and overall physical activity were evaluated prior to the start of treatment and monthly thereafter. Serum levels of glycoprotein 39 (YKL-40), a marker of cartilage degradation, and insulin-like growth factor-I (IGF-I), a growth factor associated with cartilage synthesis, were assessed at baseline and at the end of the study. Overall, SP improved OA-associated symptoms such as range of motion and several factors associated with pain and quality of life in comparison to MP. However, these beneficial effects were mainly due to the effect of SP in men rather than women. Biochemical markers of cartilage metabolism further support the efficacy of SP in men as indicated by a significant increase in serum level of IGF-I and a significant decrease in serum level of YKL-40 compared to MP. This study is the first to provide evidence of possible beneficial effects of SP in the management of OA. Examining and verifying the long-term effects of SP on improving symptoms of OA, particularly in men, is warranted.     

Changes in the flash-induced oxygen yield pattern by thylakoid membrane phosphorylation

Phosphorylation of thylakoid membrane proteins results in a partial inhibition (approximately 15–20%) of the light-saturated rate of oxygen evolution. The site of inhibition is thought to be located on the acceptor side of photosystem 2 (PS2) between the primary, Q_A, and secondary, Q_B, plastoquinone acceptors (Hodges et al. 1985, 1987). In this paper we report that thylakoid membrane phosphorylation increases the damping of the quaternary oscillation in the flash oxygen yield and increases the extent of the fast component in the deactivation of the S2 oxidation state. These results support the proposal that thylakoid membrane protein phosphorylation decreases the equilibrium constant for the exchange of an electron between Q_A and Q_B. An analysis of the oxygen release patterns using the recurrence matrix model of Lavorel (1976) indicates that thylakoid membrane phosphorylation increases the probability that PS2 miss a S-state transition by 20%. This is equivalent, however, to an insignificant inhibition (approximately 2.4%) of the light-saturated oxygen evolution rate. If a double miss in the S-state transitions is included when the PS2 centres are in S2 the fit between the experimental and theoretical oxygen yield sequences is better, and sufficient to account for the 15–20% inhibition in the steady-state oxygen yield. A double miss in the S-state transition is a consequence of an increased population of PS2 centres retaining Q_A ^–: not only will these PS2 centres fail to catalyse photochemical charge transfer until Q_A ^– is reoxidized, but the re-oxidation reaction will also result in the deactivation of S2 to S1.Abbreviations Chl Chlorophyll - PS2 Photosystem 2 - Si The oxidation states of PS2 (where i can be from 0 to 4) - Q_A ^– and Q_B ^– the anionic semiquinone forms of the primary and secondary plastoquione acceptors of PS2