Explanation and Elaboration Document for the STROBE-Vet Statement: Strengthening the Reporting of Observational Studies in Epidemiology—Veterinary Extension

The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement was first published in 2007 and again in 2014. The purpose of the original STROBE was to provide guidance for authors, reviewers and editors to improve the comprehensiveness of reporting; however, STROBE has a unique focus on observational studies. Although much of the guidance provided by the original STROBE document is directly applicable, it was deemed useful to map those statements to veterinary concepts, provide veterinary examples and highlight unique aspects of reporting in veterinary observational studies. Here, we present the examples and explanations for the checklist items included in the STROBE-Vet Statement. Thus, this is a companion document to the STROBE-Vet Statement Methods and process document, which describes the checklist and how it was developed

Fast assessment of long axis strain with standard cardiovascular magnetic resonance: a validation study of a novel parameter with reference values

Background: Assessment of longitudinal function with cardiovascular magnetic resonance (CMR) is limited to measurement of systolic excursion of the mitral annulus (MAPSE) or elaborate strain imaging modalities. The aim of this study was to develop a fast assessable parameter for the measurement of long axis strain (LAS) with CMR. Methods: 40 healthy volunteers and 125 patients with different forms of cardiomyopathy were retrospectively analyzed. Four different approaches for the assessment of LAS with CMR measuring the distance between the LV apex and a line connecting the origins of the mitral valve leaflets in enddiastole and endsystole were evaluated. Values for LAS were calculated according to the strain formula. Results: LAS derived from the distance of the epicardial apical border to the midpoint of the line connecting the mitral valve insertion points (LAS-epi/mid) proved to be the most reliable parameter for the assessment of LAS among the different approaches. LAS-epi/mid displayed the highest sensitivity (81.6 %) and specificity (97.5 %), furthermore showing the best correlation with feature tracking (FTI) derived transmural longitudinal strain (r = 0.85). Moreover, LAS-epi/mid was non-inferior to FTI in discriminating controls from patients (Area under the curve (AUC) = 0.95 vs. 0.94, p = NS). The time required for analysis of LAS-epi/mid was significantly shorter than for FTI (67 ± 8 s vs. 180 ± 14 s, p < 0.0001). Additionally, LAS-epi/mid performed significantly better than MAPSE (Delta AUC = 0.09; p < 0.005) and the ejection fraction (Delta AUC = 0.11; p = 0.0002). Reference values were derived from 234 selected healthy volunteers. Mean value for LAS-epi/mid was −17.1 ± 2.3 %. Mean values for men were significantly lower compared to women (−16.5 ± 2.2 vs. -17.9 ± 2.1 %; p < 0.0001), while LAS decreased with age. Conclusions: LAS-epi/mid is a novel and fast assessable parameter for the analysis of global longitudinal function with non-inferiority compared to transmural longitudinal strain

Variability and laboratory factors affecting the sperm chromatin structure assay in human semen

During the past decade, the sperm chromatin structure assay (SCSA) has become an important tool for assessing semen quality in the human andrology laboratory. The SCSA uses the metachromatic properties of the fluorescent dye acridine orange (AO) in combination with flow cytometry to determine the sperm DNA susceptibility to denaturation in situ. The objective of this study was to evaluate laboratory factors affecting the SCSA and the variation between replicates. Semen ejaculates from 3 healthy volunteers were analyzed using the SCSA protocol as described by Evenson and Jost (2000), determining the X-mean, Y-mean, DNA fragmentation index (DFI), standard deviation of DFI (SD-DFI), and high DNA stainability (HDS). In experiment 1, the effects of thawing time, time of day, day, laboratory technician, donor, and incubation period before analysis were investigated. In experiment 2, the effects of sheath fluid, AO equilibration buffer, day, laboratory technician, donor, and incubation period before analysis were investigated. A significant difference was found between the 3 donors with respect to the X-mean, Y-mean, DFI, SD-DFI, and HDS. It was shown that incubation of the semen samples on ice postthaw had a significant effect on the X-mean, Y-mean, DFI, and SD-DFI. The laboratory technician conducting the analysis accounted for up to 15.4% for the variation of the SCSA measurements. The time of day affected the variation for the Y-mean (23.5% of the total variation of the Y-mean), and the day affected the variation for the X-mean (82.8% of the total variation of the X-mean). Incubation on ice for 5 to 25 minutes postthaw had a significant effect on the DFI and SD-DFI in both experiments. This study shows that several protocol steps in the SCSA affect the results obtained from the assay. Precise protocol description and standardization of the SCSA are therefore essential to achieve high agreement within and between different laboratories. Copyrigh