DNA Translocation through Graphene Nanopores

Nanopores -- nanosized holes that can transport ions and molecules -- are very promising devices for genomic screening, in particular DNA sequencing. Both solid-state and biological pores suffer from the drawback, however, that the channel constituting the pore is long, viz. 10-100 times the distance between two bases in a DNA molecule (0.5 nm for single-stranded DNA). Here, we demonstrate that it is possible to realize and use ultrathin nanopores fabricated in graphene monolayers for single-molecule DNA translocation. The pores are obtained by placing a graphene flake over a microsize hole in a silicon nitride membrane and drilling a nanosize hole in the graphene using an electron beam. As individual DNA molecules translocate through the pore, characteristic temporary conductance changes are observed in the ionic current through the nanopore, setting the stage for future genomic screening

Surgical ampullectomy: an underestimated operation in the era of endoscopy

AbstractIntroductionBenign neoplastic, inflammatory or functional pathologies of the ampulla of Vater are mainly treated by primary endoscopic interventions. Consequently, transduodenal surgical ampullectomy (TSA) has been abandoned in many centres, although it represents an important tool not only after unsuccessful endoscopic treatment. The aim of the study was to analyse TSA for benign lesions of the ampulla of Vater.Patients and methodsAll patients who underwent TSA between 2001 and 2014 were included. Patients were analysed in terms of indications, postoperative morbidity and mortality as well as long-term success.ResultsEighty-three patients underwent TSA. Indications included adenomas in 44 and inflammatory stenosis in 39 patients. 96% of the patients had undergone endoscopic therapeutic approaches prior to TSA (median no. of interventions n = 3). Postoperative morbidity occurred in 20 patients (24%). There was one procedure-associated death (mortality 1.2%). The mean follow-up was 54 months. Long-term overall success rate for TSA was 83.6%. After TSA for ampullary adenoma, the recurrence rate was 4.5%.ConclusionTSA is an underestimated surgical procedure, which can be performed safely with high long-term efficacy. It can be implemented in clinical algorithms for patients with benign pathologies of the ampulla of Vater, particularly after unsuccessful endoscopic treatment

Surgical ampullectomy: an underestimated operation in the era of endoscopy

AbstractIntroductionBenign neoplastic, inflammatory or functional pathologies of the ampulla of Vater are mainly treated by primary endoscopic interventions. Consequently, transduodenal surgical ampullectomy (TSA) has been abandoned in many centres, although it represents an important tool not only after unsuccessful endoscopic treatment. The aim of the study was to analyse TSA for benign lesions of the ampulla of Vater.Patients and methodsAll patients who underwent TSA between 2001 and 2014 were included. Patients were analysed in terms of indications, postoperative morbidity and mortality as well as long-term success.ResultsEighty-three patients underwent TSA. Indications included adenomas in 44 and inflammatory stenosis in 39 patients. 96% of the patients had undergone endoscopic therapeutic approaches prior to TSA (median no. of interventions n = 3). Postoperative morbidity occurred in 20 patients (24%). There was one procedure-associated death (mortality 1.2%). The mean follow-up was 54 months. Long-term overall success rate for TSA was 83.6%. After TSA for ampullary adenoma, the recurrence rate was 4.5%.ConclusionTSA is an underestimated surgical procedure, which can be performed safely with high long-term efficacy. It can be implemented in clinical algorithms for patients with benign pathologies of the ampulla of Vater, particularly after unsuccessful endoscopic treatment

Psychometric characteristics of daily diaries for the Patient-Reported Outcomes Measurement Information System (PROMIS®): a preliminary investigation

Purpose - The Patient-Reported Outcomes (PRO) Measurement Information System (PROMIS®) has developed assessment tools for numerous PROs, most using a 7-day recall format. We examined whether modifying the recall period for use in daily diary research would affect the psychometric characteristics of several PROMIS measures. Methods - Daily versions of short-forms for three PROMIS domains (pain interference, fatigue, depression) were administered to a general population sample (n = 100) for 28 days. Analyses used multilevel item response theory (IRT) models. We examined differential item functioning (DIF) across recall periods by comparing the IRT parameters from the daily data with the PROMIS 7-day recall IRT parameters. Additionally, we examined whether the IRT parameters for day-to-day within-person changes are invariant to those for between-person (cross-sectional) differences in PROs. Results - Dimensionality analyses of the daily data suggested a single dimension for each PRO domain, consistent with PROMIS instruments. One-third of the daily items showed uniform DIF when compared with PROMIS 7-day recall, but the impact of DIF on the scale level was minor. IRT parameters for within-person changes differed from between-person parameters for 3 depression items, which were more sensitive for measuring change than between-person differences, but not for pain interference and fatigue items. Notably, mean scores from daily diaries were significantly lower than the PROMIS 7-day recall norms. Conclusions - The results provide initial evidence supporting the adaptation of PROMIS measures for daily diary research. However, scores from daily diaries cannot be directly interpreted on PROMIS norms established for 7-day recall

Limited clinical value of two consecutive post-transplant renal scintigraphy procedures

Objectives: Duration of delayed graft function (DGF) and length of hospital stay (LOS) are outcomes of interest in an era that warrants increased efficacy of transplant care whereas renal allografts originate increasingly from marginal donors. While earlier studies investigate the predictive capability of a single renal scintigraphy, this study focuses on the value for both DGF duration and LOS of consecutively performed scintigraphies. Methods: From 2011 to 2014, renal transplant recipients referred for a Tc-99m MAG3 renal scintigraphy were included in a single-center retrospective study. Primary endpoints were DGF duration and LOS. Both the first (≤ 3 days) and second scintigraphies (3–7 days after transplantation) were analyzed using a 4-grade qualitative scale and quantitative indices (TFS, cTER, MUC10, average upslope). Results: We evaluated 200 first and 108 (54%) consecutively performed scintigraphies. The Kaplan-Meier curves for DGF duration and qualitative grading of the first and second scintigraphy showed significant differences between the grades (p < 0.01). The Kaplan-Meier curve for the delta grades between these procedures (lower, equal, or higher grade) did not show significant differences (p = 0.18). Multivariate analysis showed a significant association between the qualitative grades, from the first and second scintigraphy, and DGF duration, HR 1.8 (1.4–2.2, p < 0.01) and 2.8 (1.8–4.3, p < 0.01), respectively. Conclusions: Qualitative grades of single renal scintigraphies, performed within 7 days after transplantation, can be used to make a reliable image-guided decision on the need for dialysis and to predict LOS. A consecutive renal scintigraphy, however, did not show an additional value in the assessment of DGF. Key Points: • Post-transplant renal scintigraphy procedures provide information to predict delayed graft function duration and length of hospital stay. • Performing two consecutive renal scintigraphy procedures within 1 week after transplantation does not strengthen the prediction of delayed graft function duration and length of hospital stay. • Single renal scintigraphy procedures can be used to provide clinicians and patients with a reliable indication of the need for dialysis after transplantation and the expected duration of hospitalization

Field-free deterministic ultra fast creation of skyrmions by spin orbit torques

Magnetic skyrmions are currently the most promising option to realize current-driven magnetic shift registers. A variety of concepts to create skyrmions were proposed and demonstrated. However, none of the reported experiments show controlled creation of single skyrmions using integrated designs. Here, we demonstrate that skyrmions can be generated deterministically on subnanosecond timescales in magnetic racetracks at artificial or natural defects using spin orbit torque (SOT) pulses. The mechanism is largely similar to SOT-induced switching of uniformly magnetized elements, but due to the effect of the Dzyaloshinskii-Moriya interaction (DMI), external fields are not required. Our observations provide a simple and reliable means for skyrmion writing that can be readily integrated into racetrack devices