Persistence of Fimbrial Tissue on the Ovarian Surface Following Salpingectomy

BACKGROUND: Salpingectomy is recommended as a risk-reducing strategy for epithelial tubo-ovarian cancer. The gold standard procedure is complete tubal excision. OBJECTIVE: To assess the presence of residual fimbrial/tubal tissue on ovarian surfaces following salpingectomy. DESIGN: Prospective analysis of patients undergoing salpingo-oophorectomy +/- hysterectomy for benign indications, early cervical cancer or low risk endometrial cancer at a UK National Health Service Trust. Salpingectomy +/- hysterectomy was performed initially, followed by oophorectomy within the same operation. Separately retrieved tubes and ovaries were serially sectioned and completely examined histologically. The main outcome measure was histologically identified fimbrial/ tubal tissue on ovarian surface. Chi-square/Fisher's exact tests evaluated categorical variables (SPSS-23). RESULTS: 25 consecutive cases (mean age= 54.8 years (SD=5.0), comprising 41 adnexae (9= unilateral, 16= bilateral) were analysed. 17 (68.0%), 5 (20.0%) and 3 (12.0%), procedures were performed by consultant gynaecologists, subspecialty/specialist trainees and consultant gynaecological oncologists respectively. 12/25 (48.0%) were laparoscopic and 13/25 (52.0%) involved laparotomy. 4/25 (16.0%, CI: 4.5%, 36.1%) patients or 4/41 (9.8%, CI: 2.7%, 23.1%) adnexae showed residual microscopic fimbrial tissue on the ovarian surface. Tubes/ ovaries were free of adhesions in 23 cases. Two cases had dense adnexal adhesions but neither had residual fimbrial tissue on the ovary. Residual fimbrial tissue was not significantly associated with surgical route or experience; (consultant= 3/20 (15%), trainee= 1/5 (20%), p=1.0). CONCLUSION: Residual fimbrial tissue remains on the ovary following salpingectomy in a significant proportion of cases and could impact the level of risk-reduction obtained

Protein Conformational Changes in the Bacteriorhodopsin Photocycle: Comparison of Findings from Electron and X-Ray Crystallographic Analyses

Light-driven conformational changes in the membrane protein bacteriorhodopsin have been studied extensively using X-ray and electron crystallography, resulting in the deposition of >30 sets of coordinates describing structural changes at various stages of proton transport. Using projection difference Fourier maps, we show that coordinates reported by different groups for the same photocycle intermediates vary considerably in the extent and nature of conformational changes. The different structures reported for the same intermediate cannot be reconciled in terms of differing extents of change on a single conformational trajectory. New measurements of image phases obtained by cryo-electron microscopy of the D96G/F171C/F219L triple mutant provide independent validation for the description of the large protein conformational change derived at 3.2 Å resolution by electron crystallography of 2D crystals, but do not support atomic models for light-driven conformational changes derived using X-ray crystallography of 3D crystals. Our findings suggest that independent determination of phase information from 2D crystals can be an important tool for testing the accuracy of atomic models for membrane protein conformational changes

Structural studies of T4S systems by electron microscopy

Abstract: Type IV secretion (T4S) systems are large dynamic nanomachines that transport DNA and/or proteins through the membranes of bacteria. Analysis of T4S system architecture is an extremely challenging task taking into account their multi protein organisation and lack of overall global symmetry. Nonetheless the last decade demonstrated an amazing progress achieved by X-ray crystallography and cryo-electron microscopy. In this review we present a structural analysis of this dynamic complex based on recent advances in biochemical, biophysical and structural studies

Fast Small-Scale Membrane Protein Purification and Grid Preparation for Single-Particle Electron Microscopy

The ongoing development of single-particle cryo-electron microscopy (cryo-EM) is leading to fast data acquisition, data processing, and protein structure elucidation. Quick and reliable methods to go from protein purification and optimization to grid preparation will significantly improve the reach and power of cryo-EM. Such methods would particularly constitute a tremendous advantage in structural biology of membrane proteins, whose published structures stay still far behind the number of soluble protein structures. Here we describe a fast, low-cost, and user-friendly method for the purification and cryo-EM analysis of a recombinant membrane protein. This method minimizes the amount of starting material and manipulation steps needed to go from purification to grid preparation, and could potentially be expanded to other membrane protein purification systems for its direct application in structure determination by single-particle cryo-EM