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Africa
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Lignin in Biological Systems
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
A high intake of enterolignans (enterodiol and enterolactone) on the basis of dietary intake (846 μg/day) combined with a high plasma enterolactone level was associated with a reduction in the risk of breast cancer of 64%. Research has shown enterolactone to stimulate the synthesis and circulating levels of a biochemical called sex hormone-binding globulin (SHBG). Through this activity, enterolactone may reduce the free bioavailable pool of circulating estrogen, thereby reducing estrogen penetration in tissues and the risks of an adverse estrogen balance. There is also evidence that enterolactone may inhibit biosynthesis of estrogen by blocking aromatase, a key enzyme in biosyn-thesis of estradiol. Collectively through these multiple mechanisms of action, lignans appear to have a positive influence on the estrogen balance in the body.
A case-control study of polychlorinated biphenyl association with metabolic and hormonal outcomes in polycystic ovary syndrome
Published in Journal of Environmental Science and Health, Part C, 2022
Edwina Brennan, Nitya Kumar, Daniel S. Drage, Thomas K. Cunningham, Thozhukat Sathyapalan, Jochen F. Mueller, Stephen L. Atkin
The association between the mono-ortho dioxin like PCB, PCB118, and SHBG in this study is consistent with that found in cord blood samples from mother–child pairs in a Japanese cohort.37 The lack of association in PCOS cases may be a consequence of the relatively small number of PCOS cases (n = 27) with measured SHBG levels in addition to the significantly lower SHBG levels in cases compared to controls; 51.38 versus 109.73 nmol/L, p = .042. Conversely, there may be no association when PCOS are matched by weight and age with controls. The lower SHBG levels observed in PCOS cases is consistent with systematic review and meta-analysis of 39 studies where lower SHBG levels were associated with increased risk of PCOS (SMD: −0.83, 95% CI:–1.01, −0.64).38 Although not associated, we did find that lnPCB153, lnPCB180, and ln∑PCB correlated with increasing lnSHBG, consistent with PCB and SHBG levels in cord blood samples in the PELAGIE birth cohort.39 SHBG is known to affect the bioavailability of steroid hormones by preferential binding in the order of testosterone > androstenedione > estradiol with total testosterone represented by 1–2% circulating as free testosterone, 65% bound to SHBG, and the remaining bound to albumin.40 Given that SHBG concentrations influence testosterone concentrations, higher SHBG levels may have elevated total testosterone but low bioavailable and free testosterone concentrations,40 indicating an indirect effect of PCBs on testosterone levels.
Computational prediction models for assessing endocrine disrupting potential of chemicals
Published in Journal of Environmental Science and Health, Part C, 2018
Sugunadevi Sakkiah, Wenjing Guo, Bohu Pan, Rebecca Kusko, Weida Tong, Huixiao Hong
SHBG is a plasma protein produced by the liver and present in the blood stream. SHBG binds hormones and other chemicals such as estrogens, androgens and EDCs in the blood and transports them to the target cells.122–124 Abnormal SHBG concentrations lead to various human diseases such as diabetes,125 infertility,126 cancer,127 neurotoxicity,128,129 and cardiovascular diseases.130 Hence, scientists seek to computationally predict SHBG binders and nonbinders. EDCs disrupt the endocrine system by various mechanisms. Many models have been reported for predicting chemical activity with endocrine system proteins such as AR38,121 and ER.11,33,34,66,70,91,108 However, few QSAR models have been developed to predict SHBG binding activity of chemicals.131–134