Development of a Polygenic Risk Score to Predict Diverticulitis.

BACKGROUND: Despite its prevalence and associated morbidity, we remain limited in our ability to predict the course of a patient with diverticular disease. Although several clinical and genetic risk factors have been identified, we do not know how these factors relate to one another. OBJECTIVE: Our aim was to determine whether a polygenic risk score could improve risk prediction for diverticulitis and recurrent diverticulitis compared with a model using only clinical factors. DESIGN: This is an observational study. SETTING: The study examines the predictive ability of a polygenic risk score for diverticulitis developed using prior genome-wide association studies and validated using the MyCode biobank. PATIENTS: This study included patients of European ancestry in the Geisinger Health System who were enrolled in the MyCode Community Health biobanking program. MAIN OUTCOME MEASURES: The ability of a polygenic risk score to predict diverticulosis, diverticulitis, and recurrent diverticulitis was the main outcome measure of this study. RESULTS: A total of 60,861 patients were included, of whom 9912 (16.3%) had diverticulosis or diverticulitis (5015 with diverticulosis and 4897 with diverticulitis). When divided into deciles, our polygenic risk score stratified patients by risk of both diverticulosis and diverticulitis with a 2-fold difference in disease risk between the highest and lowest deciles for diverticulitis and a 4.8-fold difference for recurrent complicated diverticulitis. When compared with clinical factors alone, our polygenic risk score was able to improve risk prediction of recurrent diverticulitis. LIMITATIONS: Our population is largely located in a single geographic region and were classified by disease status, using international classification of diseases codes. CONCLUSIONS: This predictive model stratifies patients based on genetic risk for diverticular disease. The increased frequency of recurrent disease in our high-risk patients suggests that a polygenic risk score, in addition to other factors, may help guide the discussion regarding surgical intervention. See Video Abstract . DESARROLLO DE UNA PUNTUACIN DE RIESGO POLIGNICO PARA PREDECIR LA DIVERTICULITIS: ANTECEDENTES:A pesar de su prevalencia y morbilidad asociada, nuestra capacidad para predecir el curso en un paciente con enfermedad diverticular sigue siendo limitada. Si bien se han identificado varios factores de riesgo clínicos y genéticos, no sabemos cómo se relacionan estos factores entre sí.OBJETIVO:Determinar si una puntuación de riesgo poligénico podría mejorar la predicción del riesgo de diverticulitis y diverticulitis recurrente en comparación con un modelo que utiliza solo factores clínicos.DISEÑO:Un estudio observacional que examina la capacidad predictiva de una puntuación de riesgo poligénico para la diverticulitis desarrollada usando estudios previos de asociación amplia del genoma y validada usando el biobanco MyCode.ÁMBITOS Y PACIENTES:Pacientes de ascendencia europea en el Sistema de Salud Geisinger que estaban inscritos en el programa de biobancos MyCode Community Health.PRINCIPALES MEDIDAS DE VALORACIÓN:La capacidad de una puntuación de riesgo poligénico para predecir diverticulosis, diverticulitis y diverticulitis recurrente.RESULTADOS:Se incluyeron un total de 60.861 pacientes, de los cuales 9.912 (16,3%) presentaban diverticulosis o diverticulitis (5.015 con diverticulosis y 4.897 con diverticulitis). Cuando se dividió en deciles, nuestra puntuación de riesgo poligénico estratificó a los pacientes según el riesgo de diverticulosis y diverticulitis con una diferencia de 2 veces en el riesgo de enfermedad entre los deciles más alto y más bajo para diverticulitis y una diferencia de 4,8 veces para diverticulitis complicada recurrente. En comparación con los factores clínicos solos, nuestra puntuación de riesgo poligénico pudo mejorar la predicción del riesgo de diverticulitis recurrente.LIMITACIONES:Nuestra población se encuentra en gran parte en una sola región geográfica y se clasificó por estado de enfermedad utilizando códigos de clasificación internacional de enfermedades.CONCLUSIONES:Este modelo predictivo estratifica a los pacientes en función del riesgo genético de enfermedad diverticular. La mayor frecuencia de enfermedad recurrente en nuestros pacientes de alto riesgo sugiere que un puntaje de riesgo poligénico, además de otros factores, puede ayudar a guiar la discusión sobre la intervención quirúrgica. (Traducción- Dr. Ingrid Melo ).

Influence of systemic copper toxicity on early development and metamorphosis in Xenopus laevis.

The primary objective of the present study was to examine the influence of early systemic toxicity resulting from copper (Cu) exposure on metamorphic processes in Xenopus laevis. A 28-day exposure study with copper, initiated at developmental stage 10, was performed using test concentrations of 3.0, 9.0, 27.2, 82.5, and 250 µg Cu/L. The primary endpoints included mortality, developmental stage, embryo-larval malformation, behavioral effects, hindlimb length (HLL), growth (snout-vent length [SVL] and wet body weight), and histopathology. The 28-day LC50 value with 95% confidence intervals was 61.2 (51.4-72.9) µg Cu/L with 250 µg Cu/L resulting in complete lethality. Developmental arrest in the 82.5 and delay in the 27.2 µg Cu/L treatments was observed as early as study day 10 continuing throughout the remainder of exposure. SVL-normalized HLL, body weight, and SVL in the 27.2 and 82.5 µg Cu/L treatments were significantly decreased relative to control. At 82.5 µg Cu/L, and thyroid gland size was markedly reduced when compared with controls consistent with the stage of developmental and growth arrest. Concentration-dependent findings in the intestine, liver, gills, eyes, and pharyngeal mucosa were consistent with non-endocrine systemic toxicity. These were prevalent in the 9.0 and 27.2 µg Cu/L treatment groups but were minimally evident or absent in the 82.5 µg/L group, which was attributed to developmental arrest. In conclusion, developmental delay in larvae exposed to 27.2 and 82.5 µg Cu/L was the result of systemic toxicity occurring in early development prior hypothalomo-pituitary-thyroid axis (HPT)-driven metamorphosis and was not indicative of endocrine disruption.

Exploring behavioural factors affecting nutritional supplement use among children in Honduras.

OBJECTIVE: This study explored social and behavioural factors associated with a home fortification of complementary foods program among families of undernourished children in 14 rural communities in Honduras. DESIGN: We collected and analysed survey data from a convenience sample of 196 households participating in a nutritional program using home fortification of complementary foods in 2017. The program supplied families with a soy-based atole powder fortified with micronutrients. A research team completed a face-to-face survey exploring social and behavioural factors associated with nutritional supplement use. Anthropometric measurements for participating children were abstracted from health clinic records of previous quarterly appointments. SETTING: The study took place in San Jose del Negrito, Honduras. PARTICIPANTS: Participants were parents or guardians of children enrolled in the nutrition program. RESULTS: Nearly half of participant families shared the nutritional supplement with other family members besides the index child, while 10 % reported using the supplement as a meal replacement for the child. Low education level of mothers was associated with improper use of the supplement (P = 0·005). Poorer families were more likely to share the supplement (P = 0·013). CONCLUSIONS: These results highlight the challenges of programs using home fortification of complementary foods in the context of food scarcity. Findings highlight the importance of increasing rural children's overall caloric intake, perhaps by increasing access to locally available protein sources. Results also suggest transitioning nutritional programs to family-based interventions to increase overall intended compliance to nutrition programming.

Real-Time Alignment and Reorientation of Polymer Chains in Liquid Crystal Elastomers.

Liquid crystal elastomers (LCEs) exhibit soft elasticity due to the alignment and reorientation of mesogens upon mechanical loading, which provides additional mechanisms to absorb and dissipate energy. This enhanced response makes LCEs potentially transformative materials for biomedical devices, tissue replacements, and protective equipment. However, there is a critical knowledge gap in understanding the highly rate-dependent dissipative behaviors of LCEs due to the lack of real-time characterization techniques that probe the microscale network structure and link it to the mechanical deformation of LCEs. In this work, we employ in situ optical measurements to evaluate the alignment and reorientation degree of mesogens in LCEs. The data are correlated to the quantitative physical analysis using polarized Fourier-transform infrared spectroscopy. The time scale of mesogen alignment is determined at different strain levels and loading rates. The mesogen reorientation kinetics is characterized to establish its relationship with the macroscale tensile strain, and compared to theoretical predictions. Overall, this work provides the first detailed study on the time-dependent evolution of mesogen alignment and reorientation in deformed LCEs. It also provides an effective and more accessible approach for other researchers to investigate the structural-property relationships of different types of polymers.

Use of Zip Code Based Aggregate Indicators to Assess Race Disparities in COVID-19.

Objective: In the first six months of the pandemic, information on race and ethnicity was missing for half of the US COVID-19 cases. Combining case ascertainment with census-based zip code indicators may identify COVID-19 race-ethnicity disparities in the absence of individual-level data. Design: Ecological retrospective study for the period March-July 2020. Setting: Population-based investigation, Allegheny County, Pennsylvania. Participants: All COVID-19 cases, adjusted for zip code area population, in the early period of the pandemic. Main Outcome Measures: Monthly COVID-19 incidence and requests for human services by zip code level indicators of race-ethnicity and poverty. Results: In the early period of the pandemic, COVID-19 incidence was higher in zip codes with a greater proportion of racial and ethnic minorities. Zip codes with the highest quartile of minority residents (>25.1% of population) had a COVID-19 incidence of 60.1 (95% CI: 51.7-68.5) per 10,000 in this period; zip codes with the lowest quartile of minority residents (<6.3%) had an incidence of 31.3 (95% CI: 14.4-48.2). Requests for human services during this period (volume of 211 calls and county services) confirm these disparities. Conclusion: Use of census-defined race-ethnicity proportions by zip code offers a way to identify disparities when individual race-ethnicity data are unavailable.

Anastomotic leak in patients with acute complicated diverticulitis undergoing primary anastomosis: risk factors and the role of diverting loop ileostomy.

BACKGROUND: Recent data has suggested that primary anastomosis (PA), with or without a diverting loop ileostomy (DLI), is a safe option for the treatment of acute complicated diverticulitis. This study aimed to evaluate risk factors associated with anastomotic leak in patients who underwent a sigmoid colectomy with PA and to determine whether a DLI was protective against a clinically significant anastomotic leak. METHODS: Patients with acute complicated diverticulitis who underwent a laparoscopic or open sigmoid colectomy with PA, with or without a DLI, were identified in the NSQIP PUF(2016-2017). The rates of anastomotic leak, receipt of DLI, and type of leak management were compared. Multivariate logistic regression was performed. RESULTS: There were 497 patients identified. Seventy-nine(15.9%) patients had a DLI, while 418 (84.1%) did not. Twenty-six anastomotic leaks were identified (5.2%). On multivariate analysis, current smoking (OR 4.02; 95% CI 1.44-11.26) and chronic steroid use (OR 3.84; 95% CI 1.16-12.69) were significantly associated with an increased risk of leak. Of the 26 patients with anastomotic leaks, 5 (19.2%) had a DLI. There was no significant difference in the rate of leak between those with a DLI(5; 6.3%) and those without(21; 5.3%; p = 0.59). Patients who had a DLI were significantly less likely to experience an anastomotic leak requiring re-operation (p < 0.01). CONCLUSIONS: Regardless of the presence of a DLI, chronic steroid use and smoking are associated with an increased risk of anastomotic leak in patients with acute complicated diverticulitis undergoing colectomy with PA. The presence of a diverting loop ileostomy is protective against re-operation.

3D Printing of Liquid Crystal Elastomer Foams for Enhanced Energy Dissipation Under Mechanical Insult.

Polymer foams are an essential class of lightweight materials used to protect assets against mechanical insults, such as shock and vibration. Two features are important to enhance their energy absorption characteristics: the foam structure and the matrix phase mechanical behavior. This study investigates novel approaches to control both of these features to enhance the energy absorption capability of flexible lattice foams. First, we consider 3D printing via digital light processing (DLP) as a method to control the foam mesostructure across a suite of periodic unit cells. Second, we introduce an additional energy dissipation mechanism in the solid matrix phase material by 3D printing the lattice foams with polydomain liquid crystal elastomer (LCE), which undergo a mechanically induced phase transition under large strains. This phase transition is associated with LC mesogen rotation and alignment and provides a second mechanism for mechanical energy dissipation in addition to the viscoelastic relaxation of the polymer network. We contrast the 3D printed LCE lattices with conventional, thermomechanically near-equivalent elastomer lattice foams to quantify the energy-absorbing enhancement the LCE matrix phase provides. Under cyclic quasi-static uniaxial compression conditions, the LCE lattices show dramatically enhanced energy dissipation in uniaxial compression compared to the non-LCE equivalent foams printed with a commercially available photocurable elastomer resin. The lattice geometry also plays a prominent role in determining the energy dissipation ratio between the LCE and non-LCE foams. We show that when increasing the lattice connectivity, the foam deformation transitions from bending-dominated to stretching-dominated deformations, which generates higher axial strains in the struts and higher energy dissipation in the lattice foam, as stretching allows greater mesogen rotation than bending. The LCE foams demonstrate superior energy absorption during the repeated dynamic loading during drop testing compared with the non-LCE equivalent foams, demonstrating the potential of LCEs to enhance physical protection systems against mechanical impact.

Injury Profile of Children 0-14 Years Old in Honduras.

Aim: At the University Medical School Hospital in Honduras, a paper-based injury surveillance system (InSS) registered all injury cases in the emergency department in 2013. This is the first study to identify the injury profiles of children in Honduras, using the InSS data. Materials and methods: A case-series study was carried out using the InSS. Children aged 0-14 years were identified in the data set, and the descriptive statistics and bivariate analyzes were completed using this data. Results: Of 17,971 study patients, 5,873 (32.7%) patients were 0-14 years old with an average age of 7.3 ± 4.1 years. Unintentional injuries, most commonly road traffic incidents, falls, and blunt force trauma, constituted 94.2% of the total injuries. In all, 1.9% (109) self-inflicted injuries and 3.9% (230) deliberate interpersonal injuries with 35.8% due to blunt force trauma and 22.6% due to gunshot wounds. The mortality rate was 0.2%, and 84% of children spent 3 or fewer days in the hospital. Firearm injuries were more severe and resulted in a longer hospital stay. Conclusion: Childhood injuries are highly prevalent and a public concern throughout Honduras. This study profiles these injuries of over an entire year and provides insight into the types of interventions that could be effective in preventing and managing the high burden of pediatric injuries in this region. Clinical significance: This study provides the groundwork to profiling the high burden of injuries in Honduran children. Targeted injury prevention strategies and interventions can begin to be developed and implemented using the profile.

Objetivo: En el Hospital Escuela de la Facultad de Medicina de la Universidad de Honduras, un sistema de vigilancia de lesiones en papel (InSS) registró todos los casos de lesiones en el Departamento de Emergencias en el año 2013. Utilizando los datos del InSS, este estudio es el primero en describir el perfil de las lesiones en niños en Honduras. Materiales y métodos: Se realizó un estudio de serie de casos utilizando el InSS. Se identificaron los pacientes de 0 a 14 años en el conjunto de datos, y se realizaron estadísticas descriptivas y análisis bivariados utilizando estos datos. Resultados: Hubo 5.873 pacientes de 0­14 años de un total de 17.971 pacientes (32,7%) con una edad promedio de 7,3 ± 4,1 años. Las lesiones no intencionales, más comunes fueron los eventos de tránsito, las caídas y los traumatismos contundentes; en total constituyeron el 94,2% del total de lesiones. Hubo 1.9% (109) lesiones autoinfligidas y 3.9% (230) lesiones interpersonales deliberadas con 35.8% debido a traumatismos contundentes y 22.6% debido a heridas por armas de fuego. La tasa de mortalidad fue del 0,2% y el 84% de los niños pasaron 3 días o menos en el hospital. Las lesiones por arma de fuego fueron más graves y resultaron en una estancia hospitalaria más prolongada. Conclusión: Las lesiones infantiles son altamente prevalentes y una preocupación en salud pública en Honduras. Este estudio describe estas lesiones y proporciona información sobre los tipos de intervenciones que podrían ser efectivas para prevenir y manejar la alta carga de lesiones pediátricas en esta región. Importancia clínica: El estudio proporciona la base para perfilar la alta carga de lesiones en los niños hondureños. Estrategias e intervenciones de prevención de lesiones pueden comenzar a desarrollarse e implementarse utilizando este perfil.

Seasonal Variation of Nutrient Loading in a Stoichiometric Producer-Consumer System.

Recent discoveries in ecological stoichiometry have indicated that food quality in terms of the phosphorus/carbon (P/C) ratio affects consumers whether the imbalance involves insufficient or excess nutrients. This phenomenon is called the "stoichiometric P/C knife-edge." In this study, we develop and analyze a producer-consumer model which captures this phenomenon. It assesses the effects of (external) nutrient (P) loading on consumer dynamics in an aquatic environment by mechanistically deriving and accounting for seasonal variation in nutrient loading. In the absence of seasonal effects, previous models suggest that the dynamics are Hopf bifurcation, saddle-node bifurcations, and limit cycles. However, seasonal effects can have major implications on the predicted solutions and enrich population dynamics. Bifurcation analyses demonstrate that seasonal forcing can cause both periodic and quasi-periodic solutions.

Genotypic Selection in Spatially Heterogeneous Producer-Grazer Systems Subject to Stoichiometric Constraints.

Various environmental conditions may exert selection pressures leading to adaptation of stoichiometrically important traits, such as organismal nutritional content or growth rate. We use theoretical approaches to explore the connections between genotypic selection and ecological stoichiometry in spatially heterogeneous environments. We present models of a producer and two grazing genotypes with different stoichiometric phosphorus/carbon ratios under spatially homogenous and heterogeneous conditions. Numerical experiments predict that selection of a single genotype, co-persistence of both genotypes, and extinction are possible outcomes depending on environmental conditions. Our results indicated that in spatially homogenous settings, co-persistence of both genotypes can occur when population dynamics oscillate on limit cycles near a key stoichiometric threshold on food quality. Under spatially heterogeneous settings, dynamics are more complex, where co-persistence is observed on limit cycles, as well as stable equilibria.

Mechanistically derived spatially heterogeneous producer-grazer model subject to stoichiometric constraints.

Known stoichiometric models of a two species producer-grazer ecosystem have either neglected spatial dynamics or failed to track free phosphorus in the media. In this paper we present a spatially heterogeneous model that tracks phosphorus content in the producer and free phosphorus in the media. We simulate our model numerically under various environmental conditions. Multiple equilibria, with bistability and deterministic extinction of the grazer, are possible here. In conditions that had been previously studied without tracking free phosphorus we find cases where qualitatively different behavior is observed. In particular under certain environmental conditions previous models predict stable equilibria where our model predicts stable limit cycles near the surface. Oscillatory dynamics can have consequences on the population densities, which may spend some time at low values throughout the cycles where they are in danger of stochastic extinction.

Dynamics of a stoichiometric producer-grazer system with seasonal effects on light level.

Many population systems are subject to seasonally varying environments. As a result, many species exhibit seasonal changes in their life-history parameters. It is quite natural to try to understand how seasonal forcing affects population dynamics subject to stoichiometric constraints, such as nutrient/light availability and food quality. Here, we use a variation of a stoichiometric Lotka-Volterra type model, known as the LKE model, as a case study, focusing on seasonal variation in the producer's light-dependent carrying capacity. Positivity and boundedness of model solutions are studied, as well as numerical explorations and bifurcations analyses. In the absence of seasonal effects, the LKE model suggests that the dynamics are either stable equilibrium or limit cycles. However, through bifurcation analysis we observe that seasonal forcing can lead to complicated population dynamics, including periodic and quasi-periodic solutions.

Predictors of Utilization and Quality Assessment in Robotic Rectal Cancer Resection: A Review of the National Cancer Database.

Robotic surgery (RS) is a novel treatment for rectal cancer resection (RCR); however, this technology is not widely accessible. The objective of this study is to evaluate the utilization of RS in RCR compared with open and laparoscopic techniques and to assess the quality of resection. RCR from 2010 to 2012 were identified using the National Cancer Database and placed into categories: open, laparoscopic, and robotic. A total of 23,857 patients who received open, laparoscopic, and robotic RCR were included (n = 14,735 (61.8%); 7,185 (30.1%); 1,937 (8.1%), respectively). Patients over 70 had a lower likelihood of robotic RCR. Patients with insurance were 2 times more likely to have robotic RCR. Patients at an academic/research program were more likely to undergo RS compared with a community cancer program (OR 3.6, 95% CI [2.79, 4.78]; P < 0.0001). Length of stay (LOS) was longer in open (7.9 ± 7.1) versus laparoscopic (6.6 ± 6.3) or robotic (6.8 ± 6.4) RCR (P < 0.0001). Although there was an increased likelihood of positive surgical margins with open RCR (OR 1.3, 95% CI [1.09, 1.66]; P < 0.0001), there was no difference in robotic and laparoscopic techniques. Younger insured patients at academic/research affiliated hospitals have a higher likelihood of receiving robotic RCR. Compared with open RCR, robotic RCR have a lower likelihood of positive surgical margins and shorter LOS.

Stoma creation: does onset of ostomy care education delay hospital length of stay?

BACKGROUND: Balancing patient safety with hospital length of stay (LOS) and associated cost is critically important. Subjectively, we have observed that patients undergoing ostomy creation early in the week have a shorter LOS. METHODS: We retrospectively reviewed LOS based on day of the week the operation was performed. RESULTS: We reviewed 180 patients undergoing minimally invasive surgery with planned ostomy. Group 1 underwent surgery on Monday to Wednesday (n = 77), Group 2 on Thursday (n = 49), and Group 3 on Friday (n = 54). The average LOS for Group 1, 2, and 3 was 6.2, 4.9, and 7.2 days, respectively. The average number of visits with ostomy nursing for Group 1, 2, and 3 was 2.7, 1.8, and 2.3, respectively. Day of initial ostomy nursing visit was significantly correlated between the delay to initial visit and LOS with Group 3 delayed most. CONCLUSIONS: Patients with the longest delay to initial nurse visit had the longest LOS, with Friday operations being most delayed. A contributing factor may be absence of ostomy teaching over the weekend.

Screening, Surveillance, and Treatment of Anal Intraepithelial Neoplasia.

The prevalence of anal intraepithelial neoplasia has been increasing, especially in high-risk patients, including men who have sex with men, human immunodeficiency virus positive patients, and those who are immunosuppressed. Several studies with long-term follow-up have suggested that rate of progression from high-grade squamous intraepithelial lesions to invasive anal cancer is ∼ 5%. This number is considerably higher for those at high risk. Anal cytology has been used to attempt to screen high-risk patients for disease; however, it has been shown to have very little correlation to actual histology. Patients with lesions should undergo history and physical exam including digital rectal exam and standard anoscopy. High-resolution anoscopy can be considered as well, although it is of questionable time and cost-effectiveness. Nonoperative treatments include expectant surveillance and topical imiquimod or 5-fluorouracil. Operative therapies include wide local excision and targeted ablation with electrocautery, infrared coagulation, or cryotherapy. Recurrence rates remain high regardless of treatment delivered and surveillance is paramount, although optimal surveillance regimens have yet to be established.

A comparison of DMET Plus microarray and genome-wide technologies by assessing population substructure.

OBJECTIVE: The capacity of the Affymetrix drug metabolism enzymes and transporters (DMET) Plus pharmacogenomics genotyping chip to estimate population substructure and cryptic relatedness was evaluated. The results were compared with estimates using genome-wide HapMap data for the same individuals. METHODS: For 301 unrelated individuals, spanning three continental populations and one admixed population, genotypic data were collected using the Affymetrix DMET Plus microarray. Genome-wide data on these individuals were obtained from HapMap release 3. Population substructure was assessed using Eigenstrat and ADMIXTURE software for both platforms. Cryptic relatedness was explored by inbreeding coefficient estimation. Nonparametric tests were used to determine correlations of the analytical results of the two genotyping platforms. RESULTS: Principal components analysis identified population substructure for both datasets, with 15.8 and 16.6% of the total variance explained in the first two principal components for DMET Plus and HapMap data, respectively. ADMIXTURE results correctly identified four subpopulations within each dataset. Nonparametric rank correlations indicated significant associations between analyses with an average ρ=0.7272 (P<10) across the three continental populations and ρ=0.4888 for the admixed population. Concordance correlation coefficients (average ρc=0.9693 across all four subpopulations) strongly indicate concordance between ADMIXTURE results. Inbreeding coefficients were slightly inflated (16 individuals>0.15) using DMET Plus data and no cryptic relatedness was indicated using HapMap data. The inflated inbreeding estimation could be because of the limited number of markers provided by DMET as a random sample of 1832 markers from HapMap also yielded inflated estimates of cryptic relatedness (39 individuals>0.15). Furthermore, use of single nucleotide polymorphisms located in genes involved in metabolism and transport may have different allele frequencies in subpopulations than single nucleotide polymorphisms sampled from the whole genome. CONCLUSION: The DMET Plus pharmacogenomics genotyping chip is effective in quantifying population substructure across the three continental populations and inferring the presence of an admixed population. On the basis of our results, these microarrays offer sufficient depth for covariate adjustment of population substructure in genomic association studies.

Results from a novel modification to the ligation intersphincteric fistula tract.

BACKGROUND: The ligation of intersphincteric fistula tract (LIFT) procedure for trans-sphincteric fistula-in-ano has been studied with variable success rates compared with initial reports. Failures occur mostly in the intersphincteric wound. Recently, we proposed a modification to LIFT, unroofing the fistula from internal opening to intersphincteric groove, ligating the fistula tract, but preserving the external sphincter. METHODS: This retrospective review assesses outcomes of patients undergoing the modified LIFT for trans-sphincteric fistulae. RESULTS: Sixty-six modified LIFT procedures were performed. The main cohort consisted of 56 patients, predominantly men (76.7%). Median operative time was 16 minutes. Median follow-up was 20.98 weeks. Overall cure rate was 71.42%, with a recurrence rate of 5.35% and fistula persistence in 16.07%. There was no persistent fecal incontinence. CONCLUSION: Modified LIFT is a safe procedure that is easily performed, has short operative time, eliminates the intersphincteric space, and has cure rates equal to or better than the original LIFT.

Detection of end-stage apoptosis by ApopTag® TUNEL technique.

DNA fragmentation, the end stage of apoptosis, is the measure of ultimate demise of the cell. A convenient method for examining apoptosis via DNA fragmentation is by the Terminal deoxynucleotidyl transferase (Tdt) dUTP Nick-End Labeling (TUNEL) assay where the DNA strand breaks are detected by enzymatically labeling the free 3'-OH termini with modified nucleotides. ApopTag(®) kits detect single-stranded and double-stranded breaks associated with apoptosis. This technique is also helpful to distinguish between apoptotic and necrotic cell death where the latter is associated with random DNA fragment lengths producing a DNA smear. Apoptotic cells stained positive with ApopTag(®) kits are easier to detect and their identification is more certain, as compared to the examination of simply histochemically stained tissues. In addition, quantitative results can be obtained using flow cytometry and apoptotic cells can be differentiated from necrotic cells with greater than tenfold sensitivity.

Analysis of autophagosome formation using lentiviral biosensors for live fluorescent cellular imaging.

Autophagy, a highly regulated homeostatic degradative process, allows cells to reallocate nutrients from less important to more essential processes under extreme conditions of starvation. Autophagy also prevents the buildup of damaged proteins and organelles that cause chronic tissue damage and disease. Although a topic of great interest with involvement of multiple signaling pathways, there are limitations in real-time detection of the autophagic process. EMD Millipore has developed technologies where prepackaged, ready-to-use, high-titer lentiviral particles, "lentiviral biosensors," encoding GFP- or RFP-tagged proteins provide a convenient and robust solution for fluorescent imaging of cells undergoing autophagy. Compared to nonviral transfection methods, lentiviral transduction, in many cases, offers higher transfection efficiency and more homogeneous protein expression, particularly for traditionally hard-to-transfect primary cell types. Lentiviral biosensors are ideal for use with fixed and live cell fluorescent microscopy, and are nondisruptive towards cellular function. GFP- or RFP-protein localization matches well with antibody-based immunostaining and demonstrates altered patterns of expression upon treatment with modulators of cell function and phenotype. Lentiviral biosensors provide a broadly effective, convenient method for visualization of cell behavior under a variety of physiological and pathological treatment conditions, in both endpoint and real-time imaging modalities. In this study, we focus on lentiviral biosensors containing GFP-LC3 and RFP-LC3 to study the formation of autophagosomes.