Francis Deng

Differentiated human stem cells resemble fetal, not adult, β cells

Significance Human pluripotent stem cells (hPSCs) can be produced from any person and have the potential to differentiate into any cell type in the body. This study focuses on the generation of insulin-expressing cells from hPSCs and compares their gene expression, as assayed by transcriptional gene products, to that of insulin-expressing β cells from human fetal and adult samples. We employ a new method to isolate and profile insulin-expressing cells and conclude that several different hPSC lines generate very similar insulin-expressing cells, cells whose transcripts resemble fetal rather than adult β cells. This study advances the possibility of directing the differentiation of stem cells into functional β cells by comparing and cataloging differences between hPSC-derived insulin-expressing cells and human β cells. Human pluripotent stem cells (hPSCs) have the potential to generate any human cell type, and one widely recognized goal is to make pancreatic β cells. To this end, comparisons between differentiated cell types produced in vitro and their in vivo counterparts are essential to validate hPSC-derived cells. Genome-wide transcriptional analysis of sorted insulin-expressing (INS+) cells derived from three independent hPSC lines, human fetal pancreata, and adult human islets points to two major conclusions: (i) Different hPSC lines produce highly similar INS+ cells and (ii) hPSC-derived INS+ (hPSC-INS+) cells more closely resemble human fetal β cells than adult β cells. This study provides a direct comparison of transcriptional programs between pure hPSC-INS+ cells and true β cells and provides a catalog of genes whose manipulation may convert hPSC-INS+ cells into functional β cells.

MARIS: method for analyzing RNA following intracellular sorting.

Transcriptional profiling is a key technique in the study of cell biology that is limited by the availability of reagents to uniquely identify specific cell types and isolate high quality RNA from them. We report a Method for Analyzing RNA following Intracellular Sorting (MARIS) that generates high quality RNA for transcriptome profiling following cellular fixation, intracellular immunofluorescent staining and FACS. MARIS can therefore be used to isolate high quality RNA from many otherwise inaccessible cell types simply based on immunofluorescent tagging of unique intracellular proteins. As proof of principle, we isolate RNA from sorted human embryonic stem cell-derived insulin-expressing cells as well as adult human β cells. MARIS is a basic molecular biology technique that could be used across several biological disciplines.

Pharmacodynamic Imaging Guides Dosing of a Selective Estrogen Receptor Degrader

Purpose: Estrogen receptor (ER) targeting is key in management of receptor-positive breast cancer. Currently, there are no methods to optimize anti-ER therapy dosing. This study assesses the use of 16α-18F-fluoroestradiol (18F-FES) PET for fulvestrant dose optimization in a preclinical ER+ breast cancer model. Experimental Design: In vitro, 18F-FES retention was compared with ERα protein expression (ELISA) and ESR1 mRNA transcription (qPCR) in MCF7 cells (ER+) after treatment with different fulvestrant doses. MCF7 xenografts were grown in ovariectomized nude mice and assigned to vehicle, low- (0.05 mg), medium- (0.5 mg), or high-dose (5 mg) fulvestrant treatment groups (5–7 per group). Two and 3 days after fulvestrant treatment, PET/CT was performed using 18F-FES and 18F-FDG, respectively. ER expression was assessed by immunohistochemistry, ELISA, and qPCR on xenografts. Tumor proliferation was assessed using Ki67 immunohistochemistry. Results: In vitro, we observed a parallel graded reduction in 18F-FES uptake and ER expression with increased fulvestrant doses, despite enhancement of ER mRNA transcription. In xenografts, ER expression significantly decreased with increased fulvestrant dose, despite similar mRNA expression and Ki67 staining among the treatment groups. We observed a significant dose-dependent reduction of 18F-FES PET mean standardized uptake value (SUVmean) with fulvestrant treatment but no significant difference among the treatment groups in 18F-FDG PET SUVmean. Conclusions: We demonstrated that 18F-FES uptake mirrors the dose-dependent changes in functional ER expression with fulvestrant resulting in ER degradation and/or blockade; these precede changes in tumor metabolism and proliferation. Quantitative 18F-FES PET may be useful for tracking early efficacy of ER blockade/degradation and guiding ER-targeted therapy dosing in patients with breast cancer. Clin Cancer Res; 21(6); 1340–7. ©2015 AACR.

Student-directed retrieval practice is a predictor of medical licensing examination performance.

IntroductionA large body of evidence indicates that retrieval practice (test-enhanced learning) and spaced repetition increase long-term information retention. Implementation of these strategies in medical curricula is unfortunately limited. However, students may choose to apply them autonomously when preparing for high-stakes, cumulative assessments, such as the United States Medical Licensing Examination Step 1. We examined the prevalence of specific self-directed methods of testing, with or without spaced repetition, among preclinical students and assessed the relationship between these methods and licensing examination performance.MethodsSeventy-two medical students at one institution completed a survey concerning their use of user-generated (Anki) or commercially-available (Firecracker) flashcards intended for spaced repetition and of boards-style multiple-choice questions (MCQs). Other information collected included Step 1 score, past academic performance (Medical College Admission Test [MCAT] score, preclinical grades), and psychological factors that may have affected exam preparation or performance (feelings of depression, burnout, and test anxiety).ResultsAll students reported using practice MCQs (mean 3870, SD 1472). Anki and Firecracker users comprised 31 and 49 % of respondents, respectively. In a multivariate regression model, significant independent predictors of Step 1 score included MCQs completed (unstandardized beta coefficient [B] = 2.2 × 10− 3, p < 0.001), unique Anki flashcards seen (B = 5.9 × 10− 4, p = 0.024), second-year honours (B = 1.198, p = 0.002), and MCAT score (B = 1.078, p = 0.003). Test anxiety was a significant negative predictor (B= − 1.986, p < 0.001). Unique Firecracker flashcards seen did not predict Step 1 score. Each additional 445 boards-style practice questions or 1700 unique Anki flashcards was associated with an additional point on Step 1 when controlling for other academic and psychological factors.ConclusionsMedical students engage extensively in self-initiated retrieval practice, often with spaced repetition. These practices are associated with superior performance on a medical licensing examination and should be considered for formal support by educators.

Tools to improve long-term retention of preclinical knowledge.

Tools to Improve Long-Term Retention of Preclinical Knowledge To the Editor: We commend Bow et al for developing tools to collaboratively generate flashcards. The authors claimed that their Hopkins Med Flashcards “redefined how students study preclinical material.” However, many students used the flashcards infrequently or read them like notes, an inefficient approach that epitomizes traditional studying. We contend that the authors missed an opportunity to encourage more effective strategies by dismissing programs such as Anki, a free, opensource, spaced repetition flashcard application that many students currently use.

The Meaning of Personal Accomplishment and Burnout in Radiology

The Meaning of Personal Accomplishment and Burnout in Radiology Guenette and Smith [1] reported the results of the Maslach Burnout Inventory (MBI) Health Services Survey among radiology residents in New England. Compared against historical control subjects in other specialties, radiology residents had similar mean scores in emotional exhaustion (EE) and depersonalization (DP) subscales. The authors also highlighted “notably low” scores in personal accomplishment (PA), indicating a higher degree of burnout, even though the difference was not statistically significant. They recommended further work targeting PA to reduce burnout among radiology residents. There are, however, two conceptual limitations in relating PA to burnout in radiology. First, studies and interventions on PA may only peripherally address the burnout syndrome. In studies of the factorial structure of the MBI, PA was poorly correlated with EE and DP, which in turn intercorrelate and form what some call the “core of burnout” [2]. PA and the core of burnout have different risk factors and implications. For instance, Guenette and Smith [1] found that residency year was predictive of EE and DP but not of PA. In a clinical validation study, scores in EE and DP, but not in PA, were associated with a diagnosis of work-related neurasthenia according to criteria in the 10th revision of the International Classification of Diseases [3]. EE and DP were more strongly related than PA to work-related outcomes such as organizational commitment, job satisfaction, and turnover intention [4]. Second, the PA subscale may be particularly problematic for radiologists. The MBI was derived in occupations where the worker directly provides service to recipients about potentially emotion-laden issues. The PA subscale most explicitly probes these interactions with items such as “I can easily understand how my recipients feel about things,” “I can easily create a relaxed atmosphere with my recipients,” and “In my work, I deal with emotional problems very calmly.” An ageold ambiguity arises: whom do we serve? The meaningfulness of PA varies by whether the radiologist’s primary self-concept is that of a doctor’s doctor or a patient’s doctor. The score then depends on the emotional salience of those interactions. In my opinion, many radiologists would not endorse this kind of measure to characterize their feelings of accomplishment in their daily work. Two partial solutions are suggested for future research on burnout in radiology. First, one can focus on analyzing the core of burnout with the EE and DP subscales of the MBI. Indeed, seminal studies using the MBI in physicians have excluded PA from the definition of burnout [5]. Second, one can use the MBI-General Survey (GS), a broadly relevant instrument that captures aspects of burnout beyond social relationships at work. In place of PA, the MBI-GS measures professional efficacy (PE) with generic statements such as “I can effectively solve the problems that arise in my work” and “I have accomplished many worthwhile things in this job.” In fact, the only other peer-reviewed study on burnout in radiology residents used items from the MBI-GS PE subscale, albeit with some nonvalidated modifications [6]. Much room for improvement remains for describing burnout in radiology; doing so will require matching the appropriate instrument to the realities of real-world training and practice. Francis Deng Massachusetts General Hospital, Boston, MA fdeng@mgh.harvard.edu

Minority Faculty Development Programs at US Medical Schools

Minority Faculty Development Programs at US Medical Schools To the Editor Dr Guevara and colleagues1 examined the association of minority faculty development programs at US medical schools with minority faculty representation, recruitment, and promotion, focusing on groups that are underrepresented in medicine relative to the general population. However, most contemporary faculty diversity initiatives also include Asian faculty among the groups targeted.2 Although Asian faculty accounted for 13% of all academic physicians in 2008, the group constituted only 7.4% of full professors, 3.8% of chairpersons, and 0% of deans at US medical schools.3 Thus, Asian faculty are underrepresented in academic leadership compared with more junior ranks and because they make up 6% of the general population. Because Guevara et al1 grouped Asians with whites under nonunderrepresented minority faculty, their analyses leave unanswered questions regarding advances in the representation of Asians associated with faculty development programs. Such a grouping also obscures barriers that may affect Asian physicians trying to advance in academic medicine.4,5 We propose that when discussing workforce equity and diversity, it is useful to identify minority groups that are underrepresented relative to trainee and faculty candidate pools as well as relative to the general public. Whether or not a “bamboo ceiling” actually exists in academic medicine, definitional oversights in research will leave the issue unaddressed.

Prediction bias in the MCAT exam.

In reply to Phillips: We appreciate the kind words from Dr. Phillips about our recent report of current data on the cost of medical school and the resulting education debt of medical school graduates. We focused on current data in order to inform the discussion on these topics, which is often lively and opinionated. Her perspective on how debt can influence a medical school’s “culture” is both interesting and invaluable, because while we work on behalf of U.S. medical schools, we do not work at one.