Outcomes of Macrosurgical Versus Microsurgical Vasovasostomy in Vasectomized Men: a Systematic Review and Meta-analysis

In order to restore fertility by vasectomy reversal, vasovasostomy (VV) is one of the most chosen options. During this procedure, the vas deferens is anastomosed either by a macro- or microscopical technique. Up to date, it is unknown which of these techniques shows best overall post-procedure patency and pregnancy rates. The purpose of this systematic review and meta-analysis is to reach a consensus on which technique is best for vasovasostomy and thereby better counsel patients and practitioners. A systematic review and meta-analysis on macroscopic and microscopic VV for vasectomy reversal was performed. PubMed, The Cochrane Library, Embase, and Web of Science were systematically searched from inception until 2019. Studies and associated data were evaluated by two reviewers. Primary, data on post-operative patency and pregnancy rates, interval to reversal, and post-operative complications were extracted. Proportions (95% CI) and heterogeneity scores (I2) were calculated, using a random effects model. A total of 8305 patients were included by 25 studies. Descriptive analysis showed higher post-operative patency (80.5% vs 91.4%) and pregnancy rates (47.7% vs 73.3%) after microscopic vasovasostomy. Meta-analysis produced post-operative patency proportions of 0.80 (95% CI, 0.76–0.84) and 0.88 (95% CI, 0.83–0.92) after macro- and microscopic VV respectively. Proportions of post-operative pregnancy were 0.43 (95% CI, 0.35–0.50) after macroscopic VV and 0.47 (95% CI, 0.31–0.62) after microsurgical VV. Microscopic VV is associated with higher post-operative patency and pregnancy rates compared to macroscopic vasovasostomy. However, further research is needed because of shortage in high methodological quality and variety.

Characterisation of the Fracture Path in ‘Flexible’ Refractories

The denomination ‘flexible’ is chosen in the professional jargon of refractories technology for materials able to bear relatively high strains without or with acceptable loss of strength. In many cases this term is equivalent to relatively low brittleness. Characterisation of brittleness based on fracture mechanical investigations may use figures of merit like brittleness numbers, a so called characteristic length or the R’’’’ parameter according to Hasselman. In many cases these figures show that brittleness reduction of refractories is achieved by decrease of strength with at the same time more or less unaffected specific fracture energy. Microscopic investigations of fracture paths aim to exhibit which peculiarities of crack microstructure enable this change of mechanical properties. A microscopical technique developed for this purpose separately evaluates the relative crack lengths along the grain/matrix interface, within the matrix and within the grain. Results obtained for several types of refractories show brittleness decrease is associated by an increase of the relative crack length along the grain/matrix interface and a decrease of transgranular fracture. Prefabricated microcracks and a relatively low grain/matrix bond strength may support this type of crack propagation.

Visualisation of E. coli ribosomal RNA in situ by electron spectroscopic imaging and image averaging

The structures of E. coli ribosomes have been extensively probed by electron microscopy of negatively stained and frozen hydrated preparations. Coupled with quantitative image analysis and three dimensional reconstruction, such approaches are worthwhile in defining size, shape, and quaternary organisation. The important question of how the nucleic acid and protein components are arranged with respect to each other remains difficult to answer, however. A microscopical technique that has been proposed to answer this query is electron spectroscopic imaging (ESI), in which scattered electrons with energy losses characteristic of inner shell ionisations are used to form specific elemental maps. Here, we report the use of image sorting and averaging techniques to determine the extent to which a phosphorus map of isolated ribosomal subunits can define the ribosomal RNA (rRNA) distribution within them.

Interpretation of Loss in Strength and Breaking Elongation of Resin-Treated Cotton Fibers Using Microscopical Technique

Interpretation of reduction in strength and breaking elongation of resin-treated cotton fibers using a simple light microscope and swelling agent has been shown. The effect of the three factors, namely, resin pickup, setting temperature, and setting time, has been studied. Shape and location of damage for different treatment conditions have been used to deduce the reasons of reduction in both properties. Treatment stages have been broken down to deduce the contribution of each treatment stage to the reduction in strength and breaking elongation. The results obtained showed that the loss in strength and breaking extension of resin-treated cotton fibers is due to the presence of crosslinks and chemical degradation. This is in full agreement with earlier postulation.