An update on endometriosis biomarkers.

Endometriosis is a debilitating gynecologic disorder characterized by chronic pelvic pain, pelvic adhesions and infertility. The gold standard diagnostic modality is histologically by tissue biopsy, although it can be diagnosed empirically if symptoms improve with medical treatment. A delayed diagnosis of endometriosis often leads to a significant impairment in quality of life and work productivity; hence, significant morbidity has been shown to bear a detrimental impact on society and the economy. The ongoing novel investigation into biomarkers for diagnostic or prognostic evaluation of endometriosis may aid in earlier detection, and thereby, improve patient quality-of-life as well as minimize morbidity. Currently, no single biomarker has been validated for endometriosis; however, there are emerging data on the utility of microRNA for diagnosis and prognosis of disease activity. In this brief review, we will identify and categorize the novel biomarkers for endometriosis.

Frustrated peptide chains at the fibril tip control the kinetics of growth of amyloid-ß fibrils.

Amyloid fibrillization is an exceedingly complex process in which incoming peptide chains bind to the fibril while concertedly folding. The coupling between folding and binding is not fully understood. We explore the molecular pathways of association of Aß40 monomers to fibril tips by combining time-resolved in situ scanning probe microscopy with molecular modeling. The comparison between experimental and simulation results shows that a complex supported by nonnative contacts is present in the equilibrium structure of the fibril tip and impedes fibril growth in a supersaturated solution. The unraveling of this frustrated state determines the rate of fibril growth. The kinetics of growth of freshly cut fibrils, in which the bulk fibril structure persists at the tip, complemented by molecular simulations, indicate that this frustrated complex comprises three or four monomers in nonnative conformations and likely is contained on the top of a single stack of peptide chains in the fibril structure. This pathway of fibril growth strongly deviates from the common view that the conformational transformation of each captured peptide chain is templated by the previously arrived peptide. The insights into the ensemble structure of the frustrated complex may guide the search for suppressors of Aß fibrillization. The uncovered dynamics of coupled structuring and assembly during fibril growth are more complex than during the folding of most globular proteins, as they involve the collective motions of several peptide chains that are not guided by a funneled energy landscape.