Incorporation of beta-sitosterol into the membrane increases resistance to oxidative stress and lipid peroxidation via estrogen receptor-mediated PI3K/GSK3beta signaling.

BACKGROUND: Brain lipid peroxidation has long been considered a potential therapeutic target for Alzheimer's disease (AD). beta-sitosterol (BS), a plant sterol that is prevalent in plant plasma membrane, has been suggested to have antioxidant activity. Previous studies have demonstrated that dietary BS can enter the brain and accumulates in the plasma membrane of brain cells. However, it is unknown whether and how BS exerts its antioxidant activity in plasma membrane. METHODS: To incorporate BS into the plasma membrane in vitro, HT22 cells and primarily cultured hippocampal cells were supplemented with BS using 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) as a carrier. The present study then tested the antioxidant effect of membrane BS against glucose oxidase (GOX)-induced oxidative stress and lipid peroxidation, and whether the antioxidant effect of membrane BS was associated with estrogen receptor (ER)-mediated phosphatidyl inositol 3-kinase (PL3K)/glycogen synthase kinase 3 (GSK3beta) signaling. RESULTS: Incorporation of BS into cell membrane prevented GOX-induced oxidative stress and lipid peroxidation, which could be suppressed by the ER antagonists and PI3K inhibitor. Additional experiments showed that incorporation of BS into cell membrane induced an up-regulation of PI3K activity and a recruitment of PI3K to lipid rafts, which could be inhibited by the ER antagonist. Membrane BS also increased the expression of p-GSK3beta, which could be suppressed in the presence of the ER antagonist and PI3K inhibitor. GENERAL SIGNIFICANCE: Given that BS is prevalent in foods such as plant oil, the results provide a better understanding of the beneficial effects of these BS-enriched nutrients on neurodegenerative diseases such as AD.

The GyneFix implant systems for interval, postabortal and postpartum contraception: a significant advance in long-term reversible contraception. International Study Group on Intrauterine Drug Delivery.

Intrauterine contraception has a number of important advantages over other forms of contraception and remains, therefore, an important method of birth control. However, side-effects and other drawbacks have reduced its overall acceptance. Also misconceptions and lack of updated scientific knowledge among the potential users and providers are major obstacles to the widespread use of intrauterine contraception. Ideally, an intrauterine device (IUD) should prevent pregnancy effectively, be well tolerated, not become displaced or expelled over time, cause a minimum of side-effects, be long-lasting, have a strictly local effect, and be easy to insert and remove. A group at the University of Ghent, Belgium, the International Study Group on Intrauterine Drug Delivery, has developed, since 1985, a totally new concept in order to improve current intrauterine contraceptive efficacy and enhance tolerance, by creating a harmonious relationship between the uterine cavity and the contraceptive 'foreign body'. The new concept (GyneFix) consists of a non-biodegradable suture thread made of surgical 00 monofilament polypropylene on which six copper tubes are threaded, providing a total surface area of 330 mm2. The upper and lower tubes are crimped onto the thread to keep the tubes in place. The upper extremity of the thread is provided with a knot which serves as an anchor. The knot is implanted in the myometrium of the uterine fundus with a specially designed insertion instrument, thereby permanently securing the device in the uterine cavity. Since the initial clinical investigations, over 10,000 woman years of experience and up to 10 years' follow-up in international multicenter, non-comparative and comparative clinical trials have been collected. The clinical material also included a large number of nulligravid and nulliparous women. Due to the design characteristics of the GyneFix and its anchoring in the uterine fundus, an optimal tolerance and almost complete absence of expulsion were obtained. The constant release of copper ions in the upper part of the uterine cavity results in the high effectiveness of the anchored device. The effectiveness is higher than in the high-load conventional copper IUDs which have a risk of becoming displaced, partially or totally expelled in 10% or more (nulliparous women), resulting in a significant number of accidental pregnancies. The absence of frame and, as a consequence, its flexibility, explain the low incidence of side-effects and the very low incidence of complications, such as pelvic inflammatory disease and ectopic pregnancies. This new concept could be a major step forward in the acceptance of intrauterine contraception worldwide and increase its popularity. This article reviews the experience with the new concept for interval, postabortal and postpartum contraception.