No abstract

The amyloid beta-protein precursor gives rise to the amyloid beta-protein, the principal constituent of senile plaques and a cytotoxic fragment involved in the pathogenesis of Alzheimer disease. Here we show that amyloid beta-protein precursor was proteolytically cleaved by caspases in the C terminus to generate a second unrelated peptide, called C31. The resultant C31 peptide was a potent inducer of apoptosis. Both caspase-cleaved amyloid beta-protein precursor and activated caspase-9 were present in brains of Alzheimer disease patients but not in control brains. These findings indicate the possibility that caspase cleavage of amyloid beta-protein precursor with the generation of C31 may be involved in the neuronal death associated with Alzheimer disease.

Little is known about the molecular mechanisms of androgen regulation of the FSHbeta gene; however, studies suggest that it consists of a complex feedback loop that involves multiple mechanisms acting at both the level of the hypothalamus and the pituitary. In the present study, we address androgen regulation of the FSHbeta gene in immortalized gonadotrope cells and investigate the roles of activin and GnRH in androgen action. Using transient transfection assays in the FSHbeta-expressing mouse gonadotrope cell line, LbetaT2, we demonstrate that androgens stimulate expression of an ovine FSHbeta reporter gene in a dose-dependent manner. Mutation of either of two conserved androgen response elements at -245/-231 and -153/-139 within the proximal region of the ovine FSHbeta gene promoter abolishes this stimulation, and androgen receptor binds directly to the -244 ARE in vitro. Androgen induction of the FSHbeta reporter gene is also dependent upon the activin autocrine loop present in the LbetaT2 cells, as well as an activin-response element at -138/-124 of the FSHbeta gene. However, activin regulation of other genes remains unaffected by androgens. In addition, androgens stimulate expression of a mouse GnRH receptor reporter gene, and thus may indirectly augment the response of the FSHbeta gene to GnRH. Taken together, these data demonstrate that, in mouse gonadotropes, androgens act directly on the ovine FSHbeta gene to stimulate expression by a mechanism that is dependent upon activin, as well as acting indirectly, potentially through a second mechanism that may be dependent upon induction of GnRH receptor.

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among reproductive-aged women, and it typically presents during adolescence. The objective of this review is to describe the clinical manifestations of PCOS in adolescent girls and the underlying basis for the altered reproductive physiology. Recognising adolescents at risk for PCOS and taking the appropriate steps to reduce circulating androgen levels is critical in reducing the clinical symptomatology of this disorder, and the development of adulthood infertility, diabetes, and metabolic syndrome in patients with PCOS.

Purpose To compare ovarian morphology in adolescent girls with and without polycystic ovary syndrome (PCOS) using magnetic resonance (MR) imaging. Materials and Methods In 21 adolescent girls (12–18 years) without and 19 adolescents with PCOS (diagnosis based on excessive hair growth and irregular menstrual cycles) ovarian volume, antral follicle count (AFC) per ovary, and follicle size were evaluated. MR imaging was performed at 1.5 T or 3 T and axial or angled-axial single-shot echo-train spin echo images of 6 mm slice thickness were acquired. In a subset of subjects, 2 mm images were also obtained. PCOS and non-PCOS groups were compared using mixed affects regression. Results Mean AFC per ovary and ovarian volume were substantially greater in PCOS subjects compared to non-PCOS subjects. Mean follicle size was similar between groups. Follicles exceeding 10 mm were seen in 2/19 PCOS subjects versus 9/21 non-PCOS subjects. Consistently higher follicle counts were detected in images obtained at 2 mm compared to 6 mm slice thickness. Conclusion In adolescence MR imaging of the ovary reveals distinct differences between girls with and without PCOS. MR imaging may help evaluate young patients in whom transvaginal ultrasound is contraindicated.