Tensile strength of a surgeon’s or a square knot

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Objective—To test the integrity of surgeon’s knots and flat square knots using four different suture materials. Study Design—Chromic catgut, polyglactin 910, silk, and polydioxanone sutures were tied in the two types of knot configurations. For all sutures, a 0-gauge United States Pharmacopeia suture was used. Knots were tied by a single investigator (JB). Suture was soaked in 0.9 % sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails were cut to 3 mm length. We compared the knots, measuring knot strength using a tensiometer until the sutures broke or untied. Results—A total of 119 knots were tied. We found no difference in mean tension at failure between a surgeon’s knot (79.7 Newtons) and a flat square knot (82.9 Newtons). Using a Chisquare test, we did not find a statistically significant difference in the likelihood of knots coming untied between surgeon’s knots (29%) and flat square knots (38%). Conclusions—Under laboratory conditions, surgeon’s knots and flat square knots did not differ in tension at failure or likelihood of untying

Fabrication of Electrochemical-DNA Biosensors for the Reagentless Detection of Nucleic Acids, Proteins and Small Molecules

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to receive the results. Many patients would be better served by rapid, bedside tests. To this end our laboratory and others have developed a versatile, reagentless biosensor platform that supports the quantitative, reagentless, electrochemical detection of nucleic acids (DNA, RNA), proteins (including antibodies) and small molecules analytes directly in unprocessed clinical and environmental samples. In this video, we demonstrate the preparation and use of several biosensors in this "E-DNA" class. In particular, we fabricate and demonstrate sensors for the detection of a target DNA sequence in a polymerase chain reaction mixture, an HIV-specific antibody and the drug cocaine. The preparation procedure requires only three hours of hands-on effort followed by an overnight incubation, and their use requires only minutes

Family-Based Bivariate Association Tests for Quantitative Traits

The availability of a large number of dense SNPs, high-throughput genotyping and computation methods promotes the application of family-based association tests. While most of the current family-based analyses focus only on individual traits, joint analyses of correlated traits can extract more information and potentially improve the statistical power. However, current TDT-based methods are low-powered. Here, we develop a method for tests of association for bivariate quantitative traits in families. In particular, we correct for population stratification by the use of an integration of principal component analysis and TDT. A score test statistic in the variance-components model is proposed. Extensive simulation studies indicate that the proposed method not only outperforms approaches limited to individual traits when pleiotropic effect is present, but also surpasses the power of two popular bivariate association tests termed FBAT-GEE and FBAT-PC, respectively, while correcting for population stratification. When applied to the GAW16 datasets, the proposed method successfully identifies at the genome-wide level the two SNPs that present pleiotropic effects to HDL and TG traits

Am I on Track? Evaluating Patient-Specific Weight Loss After Bariatric Surgery Using an Outcomes Calculator

PURPOSE: Individual weight loss outcomes after bariatric surgery can vary considerably. As a result, identifying and assisting patients who are not on track to reach their weight loss goals can be challenging. MATERIALS AND METHODS: Using a bariatric surgery outcomes calculator, which was formulated using a state-wide bariatric-specific data registry, predicted weight loss at 1 year after surgery was calculated on 658 patients who underwent bariatric surgery at 35 different bariatric surgery programs between 2015 and 2017. Patient characteristics, postoperative complications, and weight loss trajectories were compared between patients who met or exceeded their predicted weight loss calculation to those who did not based on observed to expected weight loss ratio (O:E) at 1 year after surgery. RESULTS: Patients who did not meet their predicted weight loss at 1 year (n = 237, 36%) had a mean O:E of 0.71, while patients who met or exceeded their prediction (n = 421, 63%) had a mean O:E = 1.14. At 6 months, there was a significant difference in the percent of the total amount of predicted weight loss between the groups (88% of total predicted weight loss for those that met their 1-year prediction vs 66% for those who did not, p \u3c 0.0001). Age, gender, procedure type, and risk-adjusted complication rates were similar between groups. CONCLUSION: Using a bariatric outcomes calculator can help set appropriate weight-loss expectations after surgery and also identify patients who may benefit from additional therapy prior to reaching their weight loss nadir

CheapStat: An Open-Source, “Do-It-Yourself” Potentiostat for Analytical and Educational Applications

Although potentiostats are the foundation of modern electrochemical research, they have seen relatively little application in resource poor settings, such as undergraduate laboratory courses and the developing world. One reason for the low penetration of potentiostats is their cost, as even the least expensive commercially available laboratory potentiostats sell for more than one thousand dollars. An inexpensive electrochemical workstation could thus prove useful in educational labs, and increase access to electrochemistry-based analytical techniques for food, drug and environmental monitoring. With these motivations in mind, we describe here the CheapStat, an inexpensive (<$80), open-source (software and hardware), hand-held potentiostat that can be constructed by anyone who is proficient at assembling circuits. This device supports a number of potential waveforms necessary to perform cyclic, square wave, linear sweep and anodic stripping voltammetry. As we demonstrate, it is suitable for a wide range of applications ranging from food- and drug-quality testing to environmental monitoring, rapid DNA detection, and educational exercises. The device's schematics, parts lists, circuit board layout files, sample experiments, and detailed assembly instructions are available in the supporting information and are released under an open hardware license

Factors associated with completion of patient surveys 1 year after bariatric surgery

BACKGROUND: Patient-reported outcomes (PRO) obtained from follow-up survey data are essential to understanding the longitudinal effects of bariatric surgery. However, capturing data among patients who are well beyond the recovery period of surgery remains a challenge, and little is known about what factors may influence follow-up rates for PRO. OBJECTIVES: To assess the effect of hospital practices and surgical outcomes on patient survey completion rates at 1 year after bariatric surgery. SETTING: Prospective, statewide, bariatric-specific clinical registry. METHODS: Patients at hospitals participating in the Michigan Bariatric Surgery Collaborative are surveyed annually to obtain information on weight loss, medication use, satisfaction, body image, and quality of life following bariatric surgery. Hospital program coordinators were surveyed in June 2017 about their practices for ensuring survey completion among their patients. Hospitals were ranked based on 1-year patient survey completion rates between 2011 and 2015. Multivariable regression analyses were used to identify associations between hospital practices, as well as 30-day outcomes, on hospital survey completion rankings. RESULTS: Overall, patient survey completion rates at 1 year improved from 2011 (33.9% ± 14.5%) to 2015 (51.0% ± 13.0%), although there was wide variability between hospitals (21.1% versus 77.3% in 2015). Hospitals in the bottom quartile for survey completion rates had higher adjusted rates of 30-day severe complications (2.6% versus 1.7%, respectively; P = .0481), readmissions (5.0% versus 3.9%, respectively; P = .0157), and reoperations (1.5% versus .7%, respectively; P = .0216) than those in the top quartile. While most hospital practices did not significantly impact survey completion at 1 year, physically handing out surveys during clinic visits was independently associated with higher completion rates (odds ratio, 13.60; 95% confidence interval, 1.99-93.03; P =.0078). CONCLUSIONS: Hospitals vary considerably in completion rates of patient surveys at 1 year after bariatric surgery, and lower rates were associated with hospitals that had higher complication rates. Hospitals with the highest completion rates were more likely to physically hand surveys to patients during clinic visits. Given the value of PRO on longitudinal outcomes of bariatric surgery, improving data collection across multiple hospital systems is imperative

Racial variation in baseline characteristics and wait times among patients undergoing bariatric surgery

BACKGROUND: Although bariatric surgery is the most effective treatment for obesity and weight-related comorbid diseases, utilization rates are disproportionately low among non-white patients. We sought to understand if variation in baseline characteristics or access to care exists between white and non-white patients. METHODS: Using a statewide bariatric-specific data registry, we evaluated all patients who underwent bariatric surgery between 2006 and 2020 and completed a preoperative baseline questionnaire, which included a question about self-identification of race. Patient characteristics, co-morbidities, and time from initial preoperative clinic evaluation to date of surgery were compared among racial groups. RESULTS: A total of 73,141 patients met inclusion criteria with 18,741 (25.5%) self-identified as non-white. These included Black/African American (n = 11,904), Hispanic (n = 3448), Asian (n = 121), Native Hawaiian/Pacific Islander (n = 41), Middle Eastern (n = 164), Multiple (n = 2047) and other (n = 608). Non-white males were the least represented group, accounting for only 4% of all bariatric cases performed. Non-white patients were more likely to be younger (43.0 years vs. 46.6 years, p \u3c 0.0001), disabled (16% vs. 11.4%, p \u3c 0.0001) and have Medicaid (8.4% vs. 3.8%, p \u3c 0.0001) when compared to white patients, despite having higher rates of college education (78.0% vs. 76.6, p \u3c 0.0001). In addition, median time from initial evaluation to surgery was also longer among non-white patients (157 days vs. 127 days, p \u3c 0.0001), despite having higher rates of patients with a body mass index above 50 kg/m(2) (39.0% vs. 33.2%, p \u3c 0.0001). CONCLUSIONS: Non-white patients undergoing bariatric surgery represent an extremely diverse group of patients with more socioeconomic disadvantages and longer wait times when compared to white patients despite presenting with higher rates of severe obesity. Current guidelines and referral patterns for bariatric surgery may not be equitable and need further examination when considering the management of obesity within diverse populations to reduce disparities in care-of which non-white males are particularly at risk

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV