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Background:Authentic research experiences and mentoring have positive impacts on fostering STEM engagement among youth from backgrounds underrepresented in STEM. Programs applying an experiential learning approach often incorporate one or both of these elements, however, there is little research on how these factors impact youth's STEM engagement during the high school to college transition. Purpose:Using a longitudinal design, this study explored the impact of a hands-on field research experience and mentoring as unique factors impacting STEM-related outcomes among underrepresented youth. We focus on the high school to college transition, a period that can present new barriers to STEM persistence. Methodology/Approach:We surveyed 189 youth before and up to 3 years after participation in a 7-week intensive summer intervention. Findings/Conclusions:Authentic research experiences was related to increased youths’ science interest and pursuit of STEM majors, even after their transition to college. Mentorship had a more indirect impact on STEM academic intentions; where positive mentorship experiences was related to youths’ reports of social connection. Implications:Programs designed for continuing STEM engagement of underrepresented youth would benefit from incorporating experiential learning approaches focused on authentic research experiences.

Abstract Objective--To evaluate the prognostic factors in uncomplicated venous leg ulcer healing. Design--Randomised parallel group controlled trial with subjects stratified by initial ulcer diameter and four months' maximum duration of [...]

The relationship between healthcare utilization before and after liver transplantation (LT), and its association with center characteristics, is incompletely understood. This was a retrospective cohort study of 34 402 adult LTs between 2002 and 2013 using Vizient inpatient claims data linked to the United Network for Organ Sharing (UNOS) database. Multivariable mixed-effects linear regression models evaluated the association between hospitalization 90 days pre-LT and the number of days alive and out of the hospital (DAOH) 1 year post-LT. Of those patients alive at LT discharge, 24.7% spent ≥30 days hospitalized during the first year. Hospitalization in the 90 days pre-LT was inversely associated with DAOH (β = –3.4 DAOH/week hospitalized pre-LT; P= .002). Centers with >30% of their liver transplant recipients hospitalized ≥30 days in the first LT year were typically smaller volume and/or transplanting higher risk recipients (Model for End-Stage Liver Disease [MELD] score ≥35, inpatient or ventilated pre-LT). In conclusion, pre-LT hospitalization predicts 1-year post-LT hospitalization independent of MELD score at the patient-level, whereas center-specific post-LT healthcare utilization is associated with certain center behaviors and selection practices.

Cardiovascular disease is a leading cause of death among liver transplant (LT) recipients. With a rising burden of posttransplantation metabolic disease, increases in cardiovascular-related morbidity and mortality may reduce life expectancy after LT. It is unknown if the risk of long-term major cardiovascular events (MCEs) differs among LT recipients with varying diabetic states. We performed a retrospective cohort study of LT recipients from 2003 through 2013 to compare the incidence of MCEs among patients (1) without diabetes, (2) with pretransplantation diabetes, (3) with de novotransient posttransplantation diabetes, and (4) with de novosustained posttransplantation diabetes. We analyzed 994 eligible patients (39% without diabetes, 24% with pretransplantation diabetes, 16% with transient posttransplantation diabetes, and 20% with sustained posttransplantation diabetes). Median follow-up was 54.7 months. Overall, 12% of patients experienced a MCE. After adjustment for demographic and clinical variables, sustained posttransplantation diabetes was the only state associated with a significantly increased risk of MCEs (subdistribution hazard ratio 1.95, 95% confidence interval 1.20–3.18). Patients with sustained posttransplantation diabetes mellitus had a 13% and 27% cumulative incidence of MCEs at 5 and 10 years, respectively. While pretransplantation diabetes has traditionally been associated with cardiovascular disease, the long-term risk of MCEs is greatest in LT recipients with sustained posttransplantation diabetes mellitus.

Liver allocation policies are evaluated by how they impact waitlisted patients, without considering broader outcomes for all patients with end-stage liver disease (ESLD) not on the waitlist. We conducted a retrospective cohort study using two nationally representative databases: HealthCore (2006–2014) and five-state Medicaid (California, Florida, New York, Ohio and Pennsylvania; 2002–2009). United Network for Organ Sharing (UNOS) linkages enabled ascertainment of waitlist- and transplant-related outcomes. We included patients aged 18–75 with ESLD (decompensated cirrhosis or hepatocellular carcinoma) using validated International Classification of Diseases, Ninth Revision (ICD-9)–based algorithms. Among 16 824 ESLD HealthCore patients, 3-year incidences of waitlisting and transplantation were 15.8% (95% confidence interval [CI] : 15.0–16.6%) and 8.1% (7.5–8.8%), respectively. Among 67 706 ESLD Medicaid patients, 3-year incidences of waitlisting and transplantation were 10.0% (9.7–10.4%) and 6.7% (6.5–7.0%), respectively. In HealthCore, the absolute ranges in states' waitlist mortality and transplant rates were larger than corresponding ranges among all ESLD patients (waitlist mortality: 13.6–38.5%, ESLD 3-year mortality: 48.9–62.0%; waitlist transplant rates: 36.3–72.7%, ESLD transplant rates: 4.8–13.4%). States’ waitlist mortality and ESLD population mortality were not positively correlated: ρ = -0.06, p-value = 0.83 (HealthCore); ρ = -0.87, p-value = 0.05 (Medicaid). Waitlist and ESLD transplant rates were weakly positively correlated in Medicaid (ρ = 0.36, p-value = 0.55) but were positively correlated in HealthCore (ρ = 0.73, p-value = 0.001). Compared to population-based metrics, waitlist-based metrics overestimate geographic disparities in access to liver transplantation.

Background: Platelet microparticles (PMPs) are a promising prognostic marker for thrombotic disorders because of their release during platelet activation. The use of flow cytometry for the enumeration of PMPs in plasma has generated controversy due to their size, which is below the stated detection limits of conventional flow cytometry instruments. The potential impact of this is an underestimation of PMP counts. Objectives/Methods: To address this possibility, we used a combination of fluorescence‐activated cell sorting (FACS) and atomic force microscopy (AFM) to determine the size distribution of PMPs present in plasma from acute myocardial infarction (AMI) patients and normal volunteers, and PMPs generated by expired platelet concentrates and washed platelets treated with agonists such as thrombin and calcium ionophore (A23187). Results: According to AFM image analysis, there was no statistically significant difference in height or volume distributions in PMPs from thrombin‐activated, calcium ionophore‐activated, expired platelet concentrates and plasma from healthy volunteers and AMI patients. Based on volume, expired platelets released the greatest proportion of exosomes (< 1.0 × 10−22 L3in volume) in relation to the entire PMP population (29.7%) and the smallest proportion of exosomes was observed in AMI patient plasma (1.8%). Moreover, AFM imaging revealed that PMPs from expired platelets exhibited smooth surfaces compared with other PMP types but this was not statistically significant. Conclusions: We confirm that flow cytometry is capable of analyzing PMPs from plasma by using AFM to perform nanoscale measurements of individual PMP events isolated by FACS. This method also provided the first quantitative nanoscale images of PMP ultrastructure.

Endoscopy with biopsy is widely employed in the management of patients with UC. The indications for endoscopy in UC are numerous but all share the common thread of impacting medical decision-making for the benefit of patient care. Recently, the role of endoscopy has been extended to the realm of prognostication, as treatment response and disease relapse historically have been very unpredictable. Although not part of standard care today, it is anticipated that future research will allow for development of highly predictive markers of the future course of UC. In addition, endoscopy may have a role in risk stratification of patients with respect to colorectal cancer, possibly leading to increased frequency of surveillance endoscopy in high-risk patients in the future.

Background & Aims: Endogenous hyperinsulinemia in the context of type 2 diabetes mellitus is potentially associated with an increased risk of colorectal cancer. We aimed to determine whether insulin therapy might increase the risk of colorectal cancer among type 2 diabetes mellitus patients. Methods: We conducted a retrospective cohort study among all patients with a diagnosis of type 2 diabetes mellitus in the General Practice Research Database from the United Kingdom. We excluded patients with <3 years of colorectal cancer-free database follow-up after the diabetes diagnosis as well as those insulin users who developed colorectal cancer after <1 year of insulin therapy. The remaining insulin users and the noninsulin-using type 2 diabetic patients were followed for the occurrence of colorectal cancer. Hazard ratios (HR) were determined in Cox proportional hazard analysis. A nested case-control study was conducted to perform multivariable analysis and to determine a duration-response effect. Results: The incidence of colorectal cancer in insulin users (n = 3160) was 197 per 100,000 person-years, compared with 124 per 100,000 person-years in type 2 diabetes mellitus patients not receiving insulin (n = 21,758). The age- and sex-adjusted HR of colorectal cancer associated with >=1 year of insulin use was 2.1 (95% CI: 1.2-3.4, P = 0.005). The positive association strengthened after adjusting for potential confounders. The multivariable odds ratio associated with each incremental year of insulin therapy was 1.21 (95% CI: 1.03-1.42, P = 0.02). Conclusions: Chronic insulin therapy significantly increases the risk of colorectal cancer among type 2 diabetes mellitus patients.

Background & Aims: Previous research has yielded conflicting data as to whether the natural history of inflammatory bowel disease follows a seasonal pattern. The purpose of this study was to determine whether relapse of inflammatory bowel disease follows a seasonal pattern either across a cohort of patients or within individual patients. Methods: We used 1988 to 1997 data from the General Practice Research Database to conduct a retrospective cohort study of 1587 patients with Crohn's disease (mean age at start of follow-up, 41 +/- 17 years) and 2773 patients with ulcerative colitis (mean age at start of follow-up, 48 +/- 16 years). Flares of disease were identified by receipt of a new prescription for either corticosteroids or 5-ASA medications following an interval of at least 4 months without prescriptions for either class of medication. Logistic regression was used to adjust the association of season of the year and flare of disease for potential confounding variables. Results: There was no association between season of the year and flare of Crohn's disease (P = 0.66). Season of the year was only weakly associated with flares of ulcerative colitis (P = 0.02). Compared with winter, spring had very slightly higher rates of flares (OR = 1.13, 95% CI: 1.05-1.23). We did not observe seasonal patterns within individual patients experiencing multiple flares (P > 0.05 for Crohn's disease and ulcerative colitis). Conclusions: Although we observed a slight increase in exacerbations of ulcerative colitis in the spring, in general, these data do not support an association between season of the year and flares.

Background & Aims:: The effect of hepatitis C viral (HCV) infection on patient and allograft survival after orthotopic liver transplantation is controversial. Hepatitis C recurrence after transplant is inevitable, but studies to date have not found a survival difference between recipients with and without HCV. Methods:: Using data from the United Network for Organ Sharing, we performed a retrospective cohort study of 11,036 patients who underwent 11,791 liver transplants between 1992 and 1998. The hazard rates of patient and allograft survival for patients who were HCV-positive as compared with patients who were HCV-negative were assessed by proportional-hazards analysis, with adjustment for potential confounding variables, including donor, recipient, and transplant center characteristics. Results:: Liver transplantation in HCV-positive recipients was associated with an increased rate of death (hazard ratio, 1.23; 95% confidence interval [Cl], 1.12-1.35) and allograft failure (hazard ratio, 1.30; 95% Cl, 1.21-1.39), as compared with transplantation in HCV-negative recipients. This reduction in survival persisted after adjusting for potential confounders. There was an interaction between HCV and sex (P < 0.001) with the effect of HCV on survival being most pronounced in female recipients (patient survival hazard ratio, 1.56; 95% Cl, 1.35-1.81; allograft survival hazard ratio, 1.51; 95% Cl, 1.34-1.70). Conclusions:: HCV infection significantly impairs patient and allograft survival after liver transplantation.

Background: Surgery, percutaneous cholangiography, and endoscopic retrograde cholangiopancreatography (ERCP) have been used in the management of biliary complications after orthotopic liver transplantation with varied results. We assessed the role of ERCP in the diagnosis, treatment, and outcome of post-orthotopic liver transplantation biliary complications. Methods: We retrospectively reviewed the records of 260 patients who underwent orthotopic liver transplantation. We examined the number of patients referred for ERCP and the indication, diagnosis, therapeutic intervention, success, and complication rate of ERCP post orthotopic liver transplantation. We compared the survival and retransplantation rates of the patients who underwent ERCP with a control group of post-orthotopic liver transplantation patients not undergoing ERCP. Results: Of the 260 patients undergoing orthotopic liver transplantation, 64 (24.6%) underwent 137 ERCPs. Two categories of indications for ERCP were identified: bile leak (n = 31) and obstruction (n = 39). ERCP identified the site of the bile leak in 27 of 31 cases (87.1%) and the leak was treated by endoscopic means in 26 of 31 (83.9%). Treatment success differed significantly based on location of the leak (T tube, 95.2% vs. anastomosis, 42.9%; p = 0.009). ERCP identified the site of obstruction in 37 of 39 cases (94.9%) and obstruction was relieved by endoscopic means in 25 of 35 cases (71.4%). ERCP was significantly less successful in the treatment of biliary casts (25.0%, p = 0.048). There was no difference in survival or retransplantation between patients who did and did not undergo ERCP. Conclusion: ERCP should be the primary method for diagnosis and treatment of post-orthotopic liver transplantation biliary complications. Endoscopic therapy is safe and effective for the majority of post-orthotopic liver transplantation complications and temporizes management for those complications that may require surgery. (Gastrointest Endosc 2000;52:55-63.)

Background & Aims: Azathioprine is a commonly used and effective treatment for maintenance of remission for patients with steroid-dependent Crohn's disease (CD). However, azathioprine therapy is associated with an increased risk of non-Hodgkin's lymphoma. The objective of this analysis was to determine the impact of azathioprine therapy on survival and quality-adjusted life expectancy after accounting for both the benefits of therapy and potential increased risk of lymphoma. Methods: A decision analysis using a Markov model depicting the natural history of alternative management strategies for maintenance of remission in patients with CD was performed. Results: In the base-case analysis, treatment of CD patients with a steroid-induced remission with azathioprine resulted in an average increase in life expectancy of 0.04 years and 0.05 quality-adjusted years. The incremental gain in life expectancy decreased with increasing patient age and increasing risk of lymphoma. Conclusions: Therapy with azathioprine to preserve remission in patients with CD results in increased quality-adjusted life expectancy. This increase was greatest in young patients who have the lowest baseline risk of non-Hodgkin's lymphoma and who have the greatest life expectancy in the absence of a CD-related death. GASTROENTEROLOGY 2000;118:1018-1024

The human U1 and U6 genes have similar basal promoter structures. A first analysis of the factor requirements for the transcription of a human U1 gene by RNA polymerase II in vitro has been undertaken, and these requirements compared with those of human U6 gene transcription by RNA polymerase III in the same extracts. Fractions containing PSE‐binding protein (PBP) are shown to be essential for transcription of both genes, and further evidence that PBP itself is required for U1 as well as U6 transcription is presented. On the other hand, the two genes have distinct requirements for TATA‐binding protein (TBP). On the basis of chromatographic and functional properties, the TBP, or TBP complex, required for U1 transcription appears to differ from previously described complexes required for RNA polymerase I, II or III transcription. The different TBP requirements of the U1 and U6 promoters are reflected by specific association with either TFIIB or TFIIIB respectively, thus providing a basis for differential RNA polymerase selection.

Unidirectional Doppler ultrasound is a simple and inexpensive adjunct to the clinical examination of varicose veins; its accuracy in determining the level of the saphenopopliteal junction has not previously been assessed. A total of 30 limbs with saphenopopliteal reflux were examined with a portable Doppler on the day of surgery and the upper limit of reflux marked. This was compared with the findings of on-table venography and surgery. Venography provided accurate anatomical information in only 84% of cases, in the failures the Doppler mark proved useful by eliminating the need for multiple incisions. Doppler estimation of the saphenopopliteal junction was correct in only 40% of cases but in nine cases out of 10 it was within 2 cm; a distance that will allow appropriate surgery through a single incision. In experienced hands the use of unidirectional doppler may eliminate the need for pre-operative venography in selected cases.

In a prospective study on an obstetric population (1,059 cases) an association was found between elevated levels of maternal serum AFP at weeks 16 to 22 and the occurrence of premature labor or the need for emergency cesarean section in the third trimester. There was no association with other late fetal complications including perinatal death, perinatal asphyxia, and intrauterine growth retardation. The sensitivity of the test in respect of premature labor was 14 per cent but the high incidence of false-positive results reduces the practical value of the test.

GASTROENTEROLOGY 2000;118:978-980

This letter describes a series of protocols, a message filtering mechanism and an error recovery procedure which allow broadcast transmission and selective message reception in a high-speed (> 1 Mbit/s) inter-computer network.

Describes the FOOD Share program in Ventura County, Calif. Senior citizens gleaning crops to feed the hungry; Social and financial benefits.

Background and Aims: Endoscopic ultrasound (EUS) is believed to be highly accurate in the T- and N-staging of pancreatic cancer. However, there is scant data demonstrating the predictive value of EUS for determining resectability of pancreatic adenocarcinoma. This study was performed to a) determine the accuracy of TNM staging by EUS in patients with pancreatic adenocarcinoma and b) to evaluate the role of preoperative TNM staging by EUS for determining resectability in patients with pancreatic adenocarcinoma. Methods: We performed a retrospective review of a cohort of 89 patients evaluated preoperatively with EUS for pancreatic adenocarcinoma between January 1995 and December 1997. Preoperative TNM classification by EUS was compared with surgical and histopathological TNM staging. Resectability rates were determined and compared to the preoperative TNM staging by EUS. Results: The overall accuracy of EUS for T- and N-staging was found to be 69% and 54%, respectively. The overall proportion of tumors that were deemed resectable by EUS and were actually found to be resectable during surgical exploration was 46%. The proportion of tumors staged as T4N1, T4N0, T3N1 and T3N0 by EUS that were found to be resectable during surgical exploration was 45%, 37%, 44% and 62%, respectively. Conclusions: In a tertiary referral population, EUS is not as accurate as previously reported in the T- and N- staging of pancreatic cancer. EUS is also not predictive of resectability in stage T3 or T4 pancreatic cancer.

GASTROENTEROLOGY 1998;115:249