The Patient-Physician Relationship: Medical Students' Perceptions in a Novel Course

The patient-physician relationship, especially in the case of severely ill patients, is often fraught with anxiety, grief, and guilt in the physician who may come to feel that he or she has failed the patient and thereby becomes a "second victim." This notion was first explored in a 1973 publication (Artiss and Levine N Engl J Med 288(23):1210-4, 1973) that described a novel interactive seminar series for oncology fellows that had been designed to address and possibly remedy the frequent disquiet experienced by young physicians in this setting. Fifty years later, the medical student co-authors of this Perspective enrolled in an elective course that comprised a similar series of interactive seminars, now addressing the contemporary patient-physician relationship. The earlier paper was employed as a historical background, and the framework of the course then broadened such that the students considered the current environmental changes in medical practice (social, cultural, financial, legal, policy) that may be linked to the character of individual patient-physician relationships. This essay reports on the students' perception of such relationships, and on the environmental elements that may be helpful or harmful to the well-being of both patients and physicians.

Causal feature selection using a knowledge graph combining structured knowledge from the biomedical literature and ontologies: a use case studying depression as a risk factor for Alzheimer's disease

BACKGROUND

Causal feature selection is essential for estimating effects from observational data. Identifying confounders is a crucial step in this process. Traditionally, researchers employ content-matter expertise and literature review to identify confounders. Uncontrolled confounding from unidentified confounders threatens validity, conditioning on intermediate variables (mediators) weakens estimates, and conditioning on common effects (colliders) induces bias. Additionally, without special treatment, erroneous conditioning on variables combining roles introduces bias. However, the vast literature is growing exponentially, making it infeasible to assimilate this knowledge. To address these challenges, we introduce a novel knowledge graph (KG) application enabling causal feature selection by combining computable literature-derived knowledge with biomedical ontologies. We present a use case of our approach specifying a causal model for estimating the total causal effect of depression on the risk of developing Alzheimer's disease (AD) from observational data.

METHODS

We extracted computable knowledge from a literature corpus using three machine reading systems and inferred missing knowledge using logical closure operations. Using a KG framework, we mapped the output to target terminologies and combined it with ontology-grounded resources. We translated epidemiological definitions of confounder, collider, and mediator into queries for searching the KG and summarized the roles played by the identified variables. We compared the results with output from a complementary method and published observational studies and examined a selection of confounding and combined role variables in-depth.

RESULTS

Our search identified 128 confounders, including 58 phenotypes, 47 drugs, 35 genes, 23 collider, and 16 mediator phenotypes. However, only 31 of the 58 confounder phenotypes were found to behave exclusively as confounders, while the remaining 27 phenotypes played other roles. Obstructive sleep apnea emerged as a potential novel confounder for depression and AD. Anemia exemplified a variable playing combined roles.

CONCLUSION

Our findings suggest combining machine reading and KG could augment human expertise for causal feature selection. However, the complexity of causal feature selection for depression with AD highlights the need for standardized field-specific databases of causal variables. Further work is needed to optimize KG search and transform the output for human consumption.

Retention, mobility, and successful transition to independence of health sciences postdocs

INTRODUCTION

Obtaining a tenure track faculty position (TTFP) after postdoctoral appointment (PDA) completion is considered an indicator of successful transition to independence (TTI). Whether cross-institutional mobility (CIM)-moving to a different institution from that of the PDA-contributes to TTI is unclear, as data evaluating retention and mobility is lacking. We tested the hypothesis that, for postdocs (PDs) at R1 institutions, CIM is a significant predictor of successful TTI defined as TTFP-status 3 years post-PDA.

MATERIALS AND METHODS

Using University of Pittsburgh data for health sciences PDs we tested the association of CIM at PDA completion (moved to a different institution (CIM = 1) or retained at Pitt (CIM = 0)) with TTFP-status 3 years post-PDA (TTFP, non-TTFP, or left faculty position) using multinomial logistic regression models.

RESULTS

Among all 622 Pitt PDs, 3-year retention in a faculty position at Pitt was 21%, while 14% had a faculty position outside of Pitt. Among the analytic sample of PDs with an academic career outcome during the study period (N = 238; 50% women, 8% underrepresented minorities (URM)), at baseline PDA completion 39% moved to a different institution (CIM = 1), and 61% remained at Pitt (CIM = 0) in any job type. Those with CIM = 1 had greater odds of having a TTFP at follow-up than those with CIM = 0 [adjusted OR (95% CI): 4.4 (2.1, 9.2)].

DISCUSSION

One fifth of Pitt PDs were retained by Pitt as faculty. While Pitt PDs were equally likely to get a faculty position whether they were retained at Pitt or left, those who left had greater odds of obtaining a TTFP. Future work with longer follow-up times, expanded markers of TTI, and samples from other R1 institutions is needed to better understand the reason for these results. This knowledge can lead to better support for the next generation of PDs as they successfully transition to faculty.

Evaluation of two longitudinal faculty leadership training programs: behavioral change and institutional impact

Purpose

Building leadership skills among faculty in academic medicine is essential, yet professional development programs focused on leadership are not always attentive to the needs of faculty on diverse career pathways or at differing career stages—nor are they often rigorously assessed. Evaluations commonly focus on participant satisfaction and short-term learning but not behavior change and institutional impact, which are difficult to assess but arguably more meaningful. Given the substantial time and money invested in these programs, more rigorous evaluation is critical.

Design/methodology/approach

The authors evaluated an intensive, shared leadership-focused training program for early-career and mid-career faculty, offered by the University of Pittsburgh’s School of Medicine over the course of a year. They administered a pre/post-program assessment of confidence in key skill areas, and conducted semi-structured interviews with 21 participants between 1–4 years after program completion.

Findings

Participants in both programs showed statistically significant improvement (p < 0.001) on every item measured in the pre/post-test. Analysis of the interviews revealed indications of substantial behavior change as well as institutional impact. The evaluation also suggested particular benefits for female professionals.

Originality/value

The authors conducted a long-term assessment of leadership training focused on career pathway and career stage and found that it (a) prompted both positive behavioral change and institutional impact and (b) suggested benefits for female faculty in particular, which could potentially help to eliminate gender-based disparities in leadership in academic medical centers.

Impact of A Required, Longitudinal Scholarly Project in Medical School: A Content Analysis of Medical Students' Reflections

INTRODUCTION

Medical schools increasingly require students to complete scholarly projects. Scholarly project programs that are required and longitudinal require considerable resources to implement. It is necessary to understand medical students' perspectives on the impact of such programs. Students at the University of Pittsburgh School of Medicine participate in a required, longitudinal research program (LRP) throughout all years of medical school training. Authors studied students' perceptions of this program.

METHODS

Fourth-year medical students submit a written report in which they reflect on their experience with the LRP. Qualitative analysis of students' written reflections was performed on 120 reports submitted 2012-2017. Content analysis was performed using an inductive approach in which investigators coded information and searched for emerging themes.

RESULTS

Four themes were identified. First, students described engaging in many steps of the research process, with many participating in projects from conception to completion. Second, students reported the LRP provided opportunities for leadership and independence, and many found this to be meaningful. Third, students developed appreciation for the difficulty of the research process through challenges encountered and practiced problem solving. Fourth, students acquired skills useful across multiple career paths, including critical appraisal of scientific literature, teamwork, and communication.

DISCUSSION

Through participation in a required, longitudinal research program, medical students reported gaining valuable skills in leadership, problem solving, critical thinking, and communication. Students found that the longitudinal nature of the program enabled meaningful research experiences. These educational impacts may be worth the effort of implementing and maintaining longitudinal research experiences for medical students.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40670-021-01319-6.

cGAS suppresses genomic instability as a decelerator of replication forks

The cyclic GMP-AMP synthase (cGAS), a sensor of cytosolic DNA, is critical for the innate immune response. Here, we show that loss of cGAS in untransformed and cancer cells results in uncontrolled DNA replication, hyperproliferation, and genomic instability. While the majority of cGAS is cytoplasmic, a fraction of cGAS associates with chromatin. cGAS interacts with replication fork proteins in a DNA binding-dependent manner, suggesting that cGAS encounters replication forks in DNA. Independent of cGAMP and STING, cGAS slows replication forks by binding to DNA in the nucleus. In the absence of cGAS, replication forks are accelerated, but fork stability is compromised. Consequently, cGAS-deficient cells are exposed to replication stress and become increasingly sensitive to radiation and chemotherapy. Thus, by acting as a decelerator of DNA replication forks, cGAS controls replication dynamics and suppresses replication-associated DNA damage, suggesting that cGAS is an attractive target for exploiting the genomic instability of cancer cells.

The Highly Structured Physician Scientist Training Program (PSTP) for Medical Students at the University of Pittsburgh

The University of Pittsburgh School of Medicine Physician Scientist Training Program (PSTP) is a 5-year medical student training program designed to prepare the next generation of MD-only physician-scientists engaging in preclinical research. This article provides an overview of the program, including the novel longitudinal structure and competency goals, which facilitate success and persistence in a laboratory-based physician-scientist career. The authors present data on 81 medical students accepted to the program from academic year 2007-2008 through 2018-2019. Extrinsic outcomes, such as publications, grant funding, and residency matching, indicate that PSTP trainees have actively generated research deliverables. A majority of eligible PSTP trainees have earned Howard Hughes Medical Institute Medical Research Fellow funding. PSTP students have produced a mean of 1.6 first-authored publications (median, 1.0) and a mean of 5.1 total publications (median, 4.0) while in medical school and have authored 0.9 publications per year as residents/fellows, excluding internship. Nearly 60% of PSTP students (26/46) have matched to top-10 National Institutes of Health-funded residency programs in their specialty (based on Blue Ridge Institute rankings). PSTP alumni are twice as likely as their classmates to match into research-heavy departments and to publish first-authored papers. Results of a 2018 program evaluation survey indicate that intrinsic outcomes, such as confidence in research skills, significantly correlate with extrinsic outcomes. The program continues to evolve to maximize both scientific agency and career navigation skills in participants. This medical student PSTP model has potential to expand the pool of physician-scientist researchers in preclinical research beyond the capacity of dedicated MD-PhD and postgraduate training programs.

m5C modification of mRNA serves a DNA damage code to promote homologous recombination

Recruitment of DNA repair proteins to DNA damage sites is a critical step for DNA repair. Post-translational modifications of proteins at DNA damage sites serve as DNA damage codes to recruit specific DNA repair factors. Here, we show that mRNA is locally modified by m⁵C at sites of DNA damage. The RNA methyltransferase TRDMT1 is recruited to DNA damage sites to promote m⁵C induction. Loss of TRDMT1 compromises homologous recombination (HR) and increases cellular sensitivity to DNA double-strand breaks (DSBs). In the absence of TRDMT1, RAD51 and RAD52 fail to localize to sites of reactive oxygen species (ROS)-induced DNA damage. In vitro, RAD52 displays an increased affinity for DNA:RNA hybrids containing m⁵C-modified RNA. Loss of TRDMT1 in cancer cells confers sensitivity to PARP inhibitors in vitro and in vivo. These results reveal an unexpected TRDMT1-m⁵C axis that promotes HR, suggesting that post-transcriptional modifications of RNA can also serve as DNA damage codes to regulate DNA repair.

Post-translational modifications of proteins at DNA damage sites can facilitate the recruitment of DNA repair factors. Here, the authors show that mRNA is locally modified with m⁵C at sites of DNA damage by the RNA methyltransferase TRDMT1 to promote homologous recombination repair.

Molecular Biology Information Service: an innovative medical library-based bioinformatics support service for biomedical researchers

Biomedical researchers are increasingly reliant on obtaining bioinformatics training in order to conduct their research. Here we present a model that academic institutions may follow to provide such training for their researchers, based on the Molecular Biology Information Service (MBIS) of the Health Sciences Library System, University of Pittsburgh (Pitt). The MBIS runs a four-facet service with the following goals: (1) identify, procure and implement commercially licensed bioinformatics software, (2) teach hands-on workshops using bioinformatics tools to solve research questions, (3) provide in-person and email consultations on software/databases and (4) maintain a web portal providing overall guidance on the access and use of bioinformatics resources and MBIS-created webtools. This paper describes these facets of MBIS activities from 2006 to 2018, including outcomes from a survey measuring attitudes of Pitt researchers about MBIS service and performance.

Exonic Variants in Aging-Related Genes Are Predictive of Phenotypic Aging Status

Background: Recent studies investigating longevity have revealed very few convincing genetic associations with increased lifespan. This is, in part, due to the complexity of biological aging, as well as the limited power of genome-wide association studies, which assay common single nucleotide polymorphisms (SNPs) and require several thousand subjects to achieve statistical significance. To overcome such barriers, we performed comprehensive DNA sequencing of a panel of 20 genes previously associated with phenotypic aging in a cohort of 200 individuals, half of whom were clinically defined by an "early aging" phenotype, and half of whom were clinically defined by a "late aging" phenotype based on age (65-75 years) and the ability to walk up a flight of stairs or walk for 15 min without resting. A validation cohort of 511 late agers was used to verify our results. Results: We found early agers were not enriched for more total variants in these 20 aging-related genes than late agers. Using machine learning methods, we identified the most predictive model of aging status, both in our discovery and validation cohorts, to be a random forest model incorporating damaging exon variants [Combined Annotation-Dependent Depletion (CADD) > 15]. The most heavily weighted variants in the model were within poly(ADP-ribose) polymerase 1 (PARP1) and excision repair cross complementation group 5 (ERCC5), both of which are involved in a canonical aging pathway, DNA damage repair. Conclusion: Overall, this study implemented a framework to apply machine learning to identify sequencing variants associated with complex phenotypes such as aging. While the small sample size making up our cohort inhibits our ability to make definitive conclusions about the ability of these genes to accurately predict aging, this study offers a unique method for exploring polygenic associations with complex phenotypes.

Scholarly Research Projects Benefit Medical Students' Research Productivity and Residency Choice: Outcomes From the University of Pittsburgh School of Medicine

PURPOSE

Many medical schools require scholarly research projects. However, outcomes data from these initiatives are scarce. The authors studied the impact of the Scholarly Research Project (SRP), a four-year longitudinal requirement for all students at the University of Pittsburgh School of Medicine (UPSOM), on research productivity and residency match.

METHOD

The authors conducted a longitudinal study of non-dual-degree UPSOM graduates in 2006 (n = 121, non-SRP participants) versus 2008 (n = 118), 2010 (n = 106), and 2012 (n = 132), all SRP participants. The authors used PubMed for publication data, National Resident Matching Program for residency match results, and Blue Ridge Institute for Medical Research for National Institutes of Health funding rank for residency-affiliated academic institutions.

RESULTS

Research productivity of students increased for those completing the SRP, measured as a greater proportion of students with publications (27.3% in 2006 vs. 45.8% in 2008, 55.7% in 2010, and 54.5% in 2012; P < .001) and first-authorship (9.9% in 2006 vs. 26.3% in 2008, 33.0% in 2010, and 35.6% in 2012; P < .001). Across years, there was a significantly greater proportion of students with peer-reviewed publications matched in higher-ranked residency programs (57.0% with publications in the top 10%, 52.7% in the top 10%-25%, 32.4% in the top 25%-50%, 41.2% in the bottom 50%, and 45.2% in unranked programs; P = .018).

CONCLUSIONS

Longitudinal research experiences for medical students may be one effective tool in fostering student publications and interest in extending training in a research-focused medical center.

ROS-induced R loops trigger a transcription-coupled but BRCA1/2-independent homologous recombination pathway through CSB

Actively transcribed regions of the genome are protected by transcription-coupled DNA repair mechanisms, including transcription-coupled homologous recombination (TC-HR). Here we used reactive oxygen species (ROS) to induce and characterize TC-HR at a transcribed locus in human cells. As canonical HR, TC-HR requires RAD51. However, the localization of RAD51 to damage sites during TC-HR does not require BRCA1 and BRCA2, but relies on RAD52 and Cockayne Syndrome Protein B (CSB). During TC-HR, RAD52 is recruited by CSB through an acidic domain. CSB in turn is recruited by R loops, which are strongly induced by ROS in transcribed regions. Notably, CSB displays a strong affinity for DNA:RNA hybrids in vitro, suggesting that it is a sensor of ROS-induced R loops. Thus, TC-HR is triggered by R loops, initiated by CSB, and carried out by the CSB-RAD52-RAD51 axis, establishing a BRCA1/2-independent alternative HR pathway protecting the transcribed genome.

SIRT6 facilitates directional telomere movement upon oxidative damage

Oxidative damage to telomeres leads to telomere attrition and genomic instability, resulting in poor cell viability. Telomere dynamics contribute to the maintenance of telomere integrity; however, whether oxidative damage induces telomere movement and how telomere mobility is regulated remain poorly understood. Here, we show that oxidative damage at telomeres triggers directional telomere movement. The presence of the human Sir2 homolog, Sirtuin 6 (SIRT6) is required for oxidative damage-induced telomeric movement. SIRT6 knock out (KO) cells show neither damage-induced telomere movement nor chromatin decondensation at damaged telomeres; both are observed in wild type (WT) cells. A deacetylation mutant of SIRT6 increases damage-induced telomeric movement in SIRT6 KO cells as well as WT SIRT6. SIRT6 recruits the chromatin-remodeling protein SNF2H to damaged telomeres, which appears to promote chromatin decondensation independent of its deacetylase activity. Together, our results suggest that SIRT6 plays a role in the regulation of telomere movement upon oxidative damage, shedding new light onto the function of SIRT6 in telomere maintenance.

RAD52 is required for RNA-templated recombination repair in post-mitotic neurons

It has been long assumed that post-mitotic neurons only utilize the error-prone non-homologous end-joining pathway to repair double-strand breaks (DSBs) associated with oxidative damage to DNA, given the inability of non-replicating neuronal DNA to utilize a sister chromatid template in the less error-prone homologous recombination (HR) repair pathway. However, we and others have found recently that active transcription triggers a replication-independent recombinational repair mechanism in G₀/G₁ phase of the cell cycle. Here we observed that the HR repair protein RAD52 is recruited to sites of DNA DSBs in terminally differentiated, post-mitotic neurons. This recruitment is dependent on the presence of a nascent mRNA generated during active transcription, providing evidence that an RNA-templated HR repair mechanism exists in non-dividing, terminally differentiated neurons. This recruitment of RAD52 in neurons is decreased by transcription inhibition. Importantly, we found that high concentrations of amyloid β, a toxic protein associated with Alzheimer's disease, inhibits the expression and DNA damage response of RAD52, potentially leading to a defect in the error-free, RNA-templated HR repair mechanism. This study shows a novel RNA-dependent repair mechanism of DSBs in post-mitotic neurons and demonstrates that defects in this pathway may contribute to neuronal genomic instability and consequent neurodegenerative phenotypes such as those seen in Alzheimer's disease.

Sino-U.S. partnerships in research, education, and patient care: The experience of the University of Pittsburgh and UPMC

In 2011, the University of Pittsburgh School of Medicine (UPSOM) and Tsinghua University formed a partnership to further the education of Tsinghua medical students. These students come to UPSOM as visiting research scholars for two years of their eight-year MD curriculum. During this time, the students, who have completed four years at Tsinghua, work full-time in medical school laboratories and research programs of their choice, essentially functioning as graduate students. In their first two months in Pittsburgh, the scholars have a one-week orientation to biomedical research, followed by two-week rotations in four labs selected on the basis of the scholars' scientific interests, after which they choose one of these labs for the remainder of the two years. Selected labs may be in basic science departments, basic science divisions of clinical departments, or specialized centers that focus on approaches like simulation and modeling. The Tsinghua students also have a brief exposure to clinical medicine. UPSOM has also formed a similar partnership with Central South University Xiangya School of Medicine in Changsha, Hunan Province. The Xiangya students come to UPSOM for two years of research training after their sixth year and, thus, unlike the Tsinghua students, have already completed their clinical rotations. UPSOM faculty members have also paved the way for UPMC (University of Pittsburgh Medical Center), UPSOM's clinical partner, to engage with clinical centers in China. Major relationships involving advisory, training, managerial, and/or equity roles exist with Xiangya International Medical Center, KingMED Diagnostics, First Chengmei Medical Industry Group, and Macare Women's Hospital. Both UPSOM and UPMC are actively exploring other clinical and academic opportunities in China.

WRN is recruited to damaged telomeres via its RQC domain and tankyrase1-mediated poly-ADP-ribosylation of TRF1

Werner syndrome (WS) is a progeroid-like syndrome caused by WRN gene mutations. WS cells exhibit shorter telomere length compared to normal cells, but it is not fully understood how WRN deficiency leads directly to telomere dysfunction. By generating localized telomere-specific DNA damage in a real-time fashion and a dose-dependent manner, we found that the damage response of WRN at telomeres relies on its RQC domain, which is different from the canonical damage response at genomic sites via its HRDC domain. We showed that in addition to steady state telomere erosion, WRN depleted cells are also sensitive to telomeric damage. WRN responds to site-specific telomeric damage via its RQC domain, interacting at Lysine 1016 and Phenylalanine1037 with the N-terminal acidic domain of the telomere shelterin protein TRF1 and demonstrating a novel mechanism for WRN's role in telomere protection. We also found that tankyrase1-mediated poly-ADP-ribosylation of TRF1 is important for both the interaction between WRN and TRF1 and the damage recruitment of WRN to telomeres. Mutations of potential tankyrase1 ADP-ribosylation sites within the RGCADG motif of TRF1 strongly diminish the interaction with WRN and the damage response of WRN only at telomeres. Taken together, our results reveal a novel mechanism as to how WRN protects telomere integrity from damage and telomere erosion.

Tankyrase1-mediated poly(ADP-ribosyl)ation of TRF1 maintains cell survival after telomeric DNA damage

Oxidative DNA damage triggers telomere erosion and cellular senescence. However, how repair is initiated at telomeres is largely unknown. Here, we found unlike PARP1-mediated Poly-ADP-Ribosylation (PARylation) at genomic damage sites, PARylation at telomeres is mainly dependent on tankyrase1 (TNKS1). TNKS1 is recruited to damaged telomeres via its interaction with TRF1, which subsequently facilitates the PARylation of TRF1 after damage. TNKS inhibition abolishes the recruitment of the repair proteins XRCC1 and polymerase β at damaged telomeres, while the PARP1/2 inhibitor only has such an effect at non-telomeric damage sites. The ANK domain of TNKS1 is essential for the telomeric damage response and TRF1 interaction. Mutation of the tankyrase-binding motif (TBM) on TRF1 (13R/18G to AA) disrupts its interaction with TNKS1 concomitant recruitment of TNKS1 and repair proteins after damage. Either TNKS1 inhibition or TBM mutated TRF1 expression markedly sensitizes cells to telomere oxidative damage as well as XRCC1 inhibition. Together, our data reveal a novel role of TNKS1 in facilitating SSBR at damaged telomeres through PARylation of TRF1, thereby protecting genome stability and cell viability.

SSRP1 Cooperates with PARP and XRCC1 to Facilitate Single-Strand DNA Break Repair by Chromatin Priming

DNA single-strand breaks (SSB) are the most common form of DNA damage, requiring repair processes that to initiate must overcome chromatin barriers. The FACT complex comprised of the SSRP1 and SPT16 proteins is important for maintaining chromatin integrity, with SSRP1 acting as an histone H2A/H2B chaperone in chromatin disassembly during DNA transcription, replication, and repair. In this study, we show that SSRP1, but not SPT16, is critical for cell survival after ionizing radiation or methyl methanesulfonate-induced single-strand DNA damage. SSRP1 is recruited to SSB in a PARP-dependent manner and retained at DNA damage sites by N-terminal interactions with the DNA repair protein XRCC1. Mutational analyses showed how SSRP1 function is essential for chromatin decondensation and histone H2B exchange at sites of DNA strand breaks, which are both critical to prime chromatin for efficient SSB repair and cell survival. By establishing how SSRP1 facilitates SSB repair, our findings provide a mechanistic rationale to target SSRP1 as a general approach to selectively attack cancer cells. Cancer Res; 77(10); 2674-85. ©2017 AACR.

Nek7 Protects Telomeres from Oxidative DNA Damage by Phosphorylation and Stabilization of TRF1

Telomeric repeat binding factor 1 (TRF1) is essential to the maintenance of telomere chromatin structure and integrity. However, how telomere integrity is maintained, especially in response to damage, remains poorly understood. Here, we identify Nek7, a member of the Never in Mitosis Gene A (NIMA) kinase family, as a regulator of telomere integrity. Nek7 is recruited to telomeres and stabilizes TRF1 at telomeres after damage in an ATM activation-dependent manner. Nek7 deficiency leads to telomere aberrations, long-lasting γH2AX and 53BP1 foci, and augmented cell death upon oxidative telomeric DNA damage. Mechanistically, Nek7 interacts with and phosphorylates TRF1 on Ser114, which prevents TRF1 from binding to Fbx4, an Skp1-Cul1-F box E3 ligase subunit, thereby alleviating proteasomal degradation of TRF1, leading to a stable association of TRF1 with Tin2 to form a shelterin complex. Our data reveal a mechanism of efficient protection of telomeres from damage through Nek7-dependent stabilization of TRF1.

Oxytocin Acting in the Nucleus Accumbens Core Decreases Food Intake

Central oxytocin (OT) promotes feeding termination in response to homeostatic challenges, such as excessive stomach distension, salt loading and toxicity. OT has also been proposed to affect feeding reward by decreasing the consumption of palatable carbohydrates and sweet tastants. Because the OT receptor (OTR) is expressed in the nucleus accumbens core (AcbC) and shell (AcbSh), a site regulating diverse aspects of eating behaviour, we investigated whether OT acts there to affect appetite in rats. First, we examined whether direct AcbC and AcbSh OT injections affect hunger- and palatability-driven consumption. We found that only AcbC OT infusions decrease deprivation-induced chow intake and reduce the consumption of palatable sucrose and saccharin solutions in nondeprived animals. These effects were abolished by pretreatment with an OTR antagonist, L-368,899, injected in the same site. AcbC OT at an anorexigenic dose did not induce a conditioned taste aversion, which indicates that AcbC OT-driven anorexia is not caused by sickness/malaise. The appetite-specific effect of AcbC OT is supported by the real-time polymerase chain reaction analysis of OTR mRNA in the AcbC, which revealed that food deprivation elevates OTR mRNA expression, whereas saccharin solution intake decreases OTR transcript levels. We also used c-Fos immunohistochemistry as a marker of neuronal activation and found that AcbC OT injection increases activation of the AcbC itself, as well as of two feeding-related sites: the hypothalamic paraventricular and supraoptic nuclei. Finally, considering the fact that OT plays a significant role in social behaviour, we examined whether offering animals a meal in a social setting would modify their hypophagic response to AcbC OT injections. We found that a social context abolishes the anorexigenic effects of AcbC OT. We conclude that OT acting via the AcbC decreases food intake driven by hunger and reward in rats offered a meal in a nonsocial setting.

Oxytocin: A Conditional Anorexigen whose Effects on Appetite Depend on the Physiological, Behavioural and Social Contexts

Central oxytocin suppresses appetite. Neuronal activity and the release of oxytocin coincide with satiation, as well as with adverse events (e.g. hyperosmolality, toxicity or excessive stomach distension) that necessitate an immediate termination of eating behaviour. Oxytocin also decreases consumption driven by reward, especially as derived from ingesting carbohydrates and sweet tastants. This review summarises current knowledge of the role of oxytocin in food intake regulation and highlights a growing body of evidence showing that oxytocin is a conditional anorexigen [i.e. its effects on appetite differ significantly with respect to certain (patho)physiological, behavioural and social contexts].

Targeted DNA damage at individual telomeres disrupts their integrity and triggers cell death

Cellular DNA is organized into chromosomes and capped by a unique nucleoprotein structure, the telomere. Both oxidative stress and telomere shortening/dysfunction cause aging-related degenerative pathologies and increase cancer risk. However, a direct connection between oxidative damage to telomeric DNA, comprising <1% of the genome, and telomere dysfunction has not been established. By fusing the KillerRed chromophore with the telomere repeat binding factor 1, TRF1, we developed a novel approach to generate localized damage to telomere DNA and to monitor the real time damage response at the single telomere level. We found that DNA damage at long telomeres in U2OS cells is not repaired efficiently compared to DNA damage in non-telomeric regions of the same length in heterochromatin. Telomeric DNA damage shortens the average length of telomeres and leads to cell senescence in HeLa cells and cell death in HeLa, U2OS and IMR90 cells, when DNA damage at non-telomeric regions is undetectable. Telomere-specific damage induces chromosomal aberrations, including chromatid telomere loss and telomere associations, distinct from the damage induced by ionizing irradiation. Taken together, our results demonstrate that oxidative damage induces telomere dysfunction and underline the importance of maintaining telomere integrity upon oxidative damage.

Research in academic medical centers: Two threats to sustainable support

Reductions in federal support and clinical revenue jeopardize biomedical research and, in turn, clinical medicine.

Ubiquitin-specific protease 5 is required for the efficient repair of DNA double-strand breaks

During the DNA damage response (DDR), ubiquitination plays an important role in the recruitment and regulation of repair proteins. However, little is known about elimination of the ubiquitination signal after repair is completed. Here we show that the ubiquitin-specific protease 5 (USP5), a deubiquitinating enzyme, is involved in the elimination of the ubiquitin signal from damaged sites and is required for efficient DNA double-strand break (DSB) repair. Depletion of USP5 sensitizes cells to DNA damaging agents, produces DSBs, causes delayed disappearance of γH2AX foci after Bleocin treatment, and influences DSB repair efficiency in the homologous recombination pathway but not in the non-homologous end joining pathway. USP5 co-localizes to DSBs induced by laser micro-irradiation in a RAD18-dependent manner. Importantly, polyubiquitin chains at sites of DNA damage remained for longer periods in USP5-depleted cells. Our results show that disassembly of polyubiquitin chains by USP5 at sites of damage is important for efficient DSB repair.

Novel method for site-specific induction of oxidative DNA damage reveals differences in recruitment of repair proteins to heterochromatin and euchromatin

Reactive oxygen species (ROS)-induced DNA damage is repaired by the base excision repair pathway. However, the effect of chromatin structure on BER protein recruitment to DNA damage sites in living cells is poorly understood. To address this problem, we developed a method to specifically produce ROS-induced DNA damage by fusing KillerRed (KR), a light-stimulated ROS-inducer, to a tet-repressor (tetR-KR) or a transcription activator (TA-KR). TetR-KR or TA-KR, bound to a TRE cassette (∼90 kb) integrated at a defined genomic locus in U2OS cells, was used to induce ROS damage in hetero- or euchromatin, respectively. We found that DNA glycosylases were efficiently recruited to DNA damage in heterochromatin, as well as in euchromatin. PARP1 was recruited to DNA damage within condensed chromatin more efficiently than in active chromatin. In contrast, recruitment of FEN1 was highly enriched at sites of DNA damage within active chromatin in a PCNA- and transcription activation-dependent manner. These results indicate that oxidative DNA damage is differentially processed within hetero or euchromatin.

Damage response of XRCC1 at sites of DNA single strand breaks is regulated by phosphorylation and ubiquitylation after degradation of poly(ADP-ribose)

Single-strand breaks (SSBs) are the most common type of oxidative DNA damage and they are related to aging and many genetic diseases. The scaffold protein for repair of SSBs, XRCC1, accumulates at sites of poly(ADP-ribose) (pAR) synthesized by PARP, but it is retained at sites of SSBs after pAR degradation. How XRCC1 responds to SSBs after pAR degradation and how this affects repair progression are not well understood. We found that XRCC1 dissociates from pAR and is translocated to sites of SSBs dependent on its BRCTII domain and the function of PARG. In addition, phosphorylation of XRCC1 is also required for the proper dissociation kinetics of XRCC1 because (1) phosphorylation sites mutated in XRCC1 (X1 pm) cause retention of XRCC1 at sites of SSB for a longer time compared to wild type XRCC1; and (2) phosphorylation of XRCC1 is required for efficient polyubiquitylation of XRCC1. Interestingly, a mutant of XRCC1, LL360/361DD, which abolishes pAR binding, shows significant upregulation of ubiquitylation, indicating that pARylation of XRCC1 prevents the poly-ubiquitylation. We also found that the dynamics of the repair proteins DNA polymerase beta, PNK, APTX, PCNA and ligase I are regulated by domains of XRCC1. In summary, the dynamic damage response of XRCC1 is regulated in a manner that depends on modifications of polyADP-ribosylation, phosphorylation and ubiquitylation in live cells.

Monoubiquitinated histone H2A destabilizes photolesion-containing nucleosomes with concomitant release of UV-damaged DNA-binding protein E3 ligase

How the nucleotide excision repair (NER) machinery gains access to damaged chromatinized DNA templates and how the chromatin structure is modified to promote efficient repair of the non-transcribed genome remain poorly understood. The UV-damaged DNA-binding protein complex (UV-DDB, consisting of DDB1 and DDB2, the latter of which is mutated in xeroderma pigmentosum group E patients, is a substrate-recruiting module of the cullin 4B-based E3 ligase complex, DDB1-CUL4B^DDB2. We previously reported that the deficiency of UV-DDB E3 ligases in ubiquitinating histone H2A at UV-damaged DNA sites in the xeroderma pigmentosum group E cells contributes to the faulty NER in these skin cancer-prone patients. Here, we reveal the mechanism by which monoubiquitination of specific H2A lysine residues alters nucleosomal dynamics and subsequently initiates NER. We show that DDB1-CUL4B^DDB2 E3 ligase specifically binds to mononucleosomes assembled with human recombinant histone octamers and nucleosome-positioning DNA containing cyclobutane pyrimidine dimers or 6-4 photoproducts photolesions. We demonstrate functionally that ubiquitination of H2A Lys-119/Lys-120 is necessary for destabilization of nucleosomes and concomitant release of DDB1-CUL4B^DDB2 from photolesion-containing DNA. Nucleosomes in which these lysines are replaced with arginines are resistant to such structural changes, and arginine mutants prevent the eviction of H2A and dissociation of polyubiquitinated DDB2 from UV-damaged nucleosomes. The partial eviction of H3 from the nucleosomes is dependent on ubiquitinated H2A Lys-119/Lys-120. Our results provide mechanistic insight into how post-translational modification of H2A at the site of a photolesion initiates the repair process and directly affects the stability of the human genome.

Effects of butorphanol on feeding and neuropeptide Y in the rat

Butorphanol ([BT] an opioid receptor agonist/antagonist) is different from other opioid agonists in that a single dose of BT can elicit up to 12 g of chow intake in a satiated rat whereas most opioid agonists induce a mild feeding response (2-3 g). Here, we first examined whether the effectiveness of BT to elicit feeding was affected by dose, method of infusion and possible tachyphylaxis following administration. Secondly, we examined whether BT administration influenced hypothalamic NPY gene expression and peptide levels. A single dose administration of BT (4 mg/kg) significantly increased food intake at 2, 3 and 6 h after administration. However following repeated injections of BT at 4 mg/kg, the cumulative long-term intake of BT-treated rats did not differ from that of controls, indicating that the animals compensate for the increased feeding following BT injection by decreased feeding at a later time. An ascending dose schedule of repeated BT injections resulted in additional feeding. NPY gene expression in the ARC was influenced by how much food had been consumed, but not by BT. The amount of food consumed and the level of NPY mRNA were inversely correlated. This is consistent with NPY's role in normal feeding. BT treatment did not affect either NPY or leptin RIA levels. We conclude that the feeding produced by BT is sensitive to dose and dosing paradigm. Further, its mechanism of action does not appear to be mediated by NPY or leptin pathways.

Co-localization of DNA repair proteins with UV-induced DNA damage in locally irradiated cells

This chapter describes a technique in which indirect immunofluorescence is applied to visualize the process of nucleotide excision repair (NER) at the site of locally induced damage in DNA. UV-irradiation of cells through an isopore polycarbonate membrane filter generates cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts (6-4PP) on a subnuclear area, which corresponds to the size of a pore on the membrane. Specific antibodies to CPD and 6-4PP define the damaged spot. The NER components co-localize at the damaged-DNA subnuclear spot, where the proteins are stained with the appropriate fluorescent antibodies. This relatively simple and affordable method facilitates the examination of the sequential assembly of NER proteins in the chromatin-embedded DNA photoproducts. The method also enhances the identification of repair auxiliary proteins and complexes, such as ubiquitin E3 ligases, involved in the initiation of NER on non-transcribed DNA.

Implementation of a longitudinal mentored scholarly project: an approach at two medical schools

An increasing number of medical schools have implemented or are considering implementing scholarly activity programs as part of their undergraduate medical curricula. The goal of these programs is to foster students' analytical skills, enhance their self-directed learning and their oral and written communication skills, and ultimately to train better physicians. In this article, the authors describe the approach to implementing scholarly activities at a school that requires this activity and at a school where it is elective. Both programs have dealt with significant challenges including orienting students to a complex activity that is fundamentally different than traditional medical school courses and clerkships, helping both students and their mentors understand how to "stay on track" and complete work, especially during the third and fourth years, and educating students and mentors about the responsible conduct of research, especially involving human participants. Both schools have found the implementation process to be evolutionary, requiring experience before faculty could significantly improve processes. A required scholarly activity has highlighted the need for information technology (IT) support, including Web-based document storage and student updates, as well as automatic e-mails alerting supervisory individuals to student activity. Directors of the elective program have found difficulty with both ensuring uniform outcomes across different areas of study and leadership changes in a process that has been largely student-driven. Both programs have found that teamwork, regular meetings, and close communication have helped with implementation. Schools considering the establishment of a scholarly activity should consider these factors when designing programs.

Inverse association of high-fat diet preference and anxiety-like behavior: a putative role for urocortin 2

The aim of this study was to investigate whether the preference for a palatable high-fat diet (HFD) is associated with response to novelty and with anxiety-like behavior in rats and whether such fat preference correlates with gene expression of hypothalamic neuropeptides related to feeding. We subjected male rats to two tests of exploration of novel environments: the multivariate concentric square field (MCSF) and the elevated plus maze (EPM). The rats were then exposed to a 5-day test of preference for a palatable HFD versus reference diets. Messenger RNA (mRNA) levels of 21 neuropeptides were investigated by quantitative polymerase chain reaction. We found a strong positive correlation of HFD preference and open-arm activity in the EPM (% open-arm time, r(s) = 0.629, df = 26, P < 0.001). Thus, HFD preference was inversely associated with anxiety-like behavior. The same association was found for HFD preference and behavior in the MCSF (bridge entries, r(s) = 0.399, df = 23, P = 0.048). In addition, the HFD preference was positively correlated (r(s) = 0.433, df = 25, P = 0.021) with hypothalamic mRNA levels of urocortin 2 (Ucn 2). Moreover, behavior in the EPM was significantly correlated with expression levels of the receptor for Ucn 2, the corticotropin-releasing factor receptor 2, in the hypothalamus (r(s) = 0.382, df = 33, P = 0.022, pituitary (r(s) = 0.494, df = 31, P = 0.004) and amygdala (r(s) = 0.381, df = 30, P = 0.032). We conclude that preference for palatable HFD is inversely associated with anxiety and propose that Ucn 2 signaling may play a role in this association.

The relationship between the University of Pittsburgh School of Medicine and the University of Pittsburgh Medical Center--a profile in synergy

In the synergistic evolution of their research, educational, and clinical programs, the University of Pittsburgh (Pitt) School of Medicine (SOM) and the University of Pittsburgh Medical Center (UPMC) have followed one core principle: What is good for one is good for both. The collaboration is underpinned by UPMC's commitment to its community mission, including support for the academic and research objectives of the SOM. UPMC's conceptual origin was fostered by its experience with Western Psychiatric Institute and Clinic in the 1970s. Over time, UPMC acquired other hospitals through merger and negotiation and, by 2008, had grown into a $7 billion global health enterprise. From the outset, the senior leaders of both UPMC and Pitt committed to collaborative decision making on all key issues. Under this coordinated decision-making model, UPMC oversees all clinical activity, including that from a consolidated physicians' practice plan. Pitt remains the guardian of all academic priorities, particularly faculty-based research. UPMC's steady financial success underpins the model. A series of interrelated agreements formally defines the relationship between Pitt and UPMC, including shared board seats and UPMC's committed ongoing financial support of the SOM. In addition, the two institutions have jointly made research growth a priority. The payoff from this dynamic has been a steadily growing Pitt research portfolio; enhanced growth, visibility, and stature for UPMC, the SOM, and Pitt as a whole; and the sustained success of UPMC's clinical enterprise, which now has an international scope. Given the current stagnation in the National Institutes of Health budget, the Pitt-UPMC experience may be instructive to other academic health centers.

Back to the basic sciences: an innovative approach to teaching senior medical students how best to integrate basic science and clinical medicine

Abraham Flexner persuaded the medical establishment of his time that teaching the sciences, from basic to clinical, should be a critical component of the medical student curriculum, thus giving rise to the "preclinical curriculum." However, students' retention of basic science material after the preclinical years is generally poor. The authors believe that revisiting the basic sciences in the fourth year can enhance understanding of clinical medicine and further students' understanding of how the two fields integrate. With this in mind, a return to the basic sciences during the fourth year of medical school may be highly beneficial. The purpose of this article is to (1) discuss efforts to integrate basic science into the clinical years of medical student education throughout the United States and Canada, and (2) describe the highly developed fourth-year basic science integration program at the University of Pittsburgh School of Medicine. In their critical review of medical school curricula of 126 U.S. and 17 Canadian medical schools, the authors found that only 19% of U.S. medical schools and 24% of Canadian medical schools require basic science courses or experiences during the clinical years, a minor increase compared with 1985. Curricular methods ranged from simple lectures to integrated case studies with hands-on laboratory experience. The authors hope to advance the national discussion about the need to more fully integrate basic science teaching throughout all four years of the medical student curriculum by placing a curricular innovation in the context of similar efforts by other U.S. and Canadian medical schools.

In-depth learning: one school's initiatives to foster integration of ethics, values, and the human dimensions of medicine

Today's medical student curriculum is a lock-step experience that provides a broad survey of medicine with little opportunity to pursue fully integrated, in-depth learning. To teach students about the human dimensions of health care, many schools simply have added courses that survey general areas such as ethics, values, and patient-doctor relationships. However, a superficial, broad-brush approach does not offer students sufficient opportunity to engage with these topics in substantive and meaningful ways. The authors propose that a theme-based, individualized, in-depth learning experience (in which students pursue a focused project comprehensively and in detail)--one that is an integral part of the curriculum--helps students learn to blend values and ethics with medicine in a way that cannot occur during rapid-paced topical survey courses. Furthermore, it is in the depths of a learning experience that one comes face to face with the realities of uncertainty: the realization that unanswerable questions outnumber answerable ones; the awareness of the difficulty in accumulating sufficient evidence to answer a question that is, in fact, answerable; the recognition that many patients' problems transcend available evidence and must be addressed by the art of medicine; the realization that a patient can have a condition that one cannot diagnose and that may even get better for reasons that one cannot understand. The authors describe three initiatives at the University of Pittsburgh School of Medicine, two of which have been offered for more than 10 years, that illustrate the value of in-depth learning experiences. These in-depth experiences blend situated learning, reflective exercises, faculty mentoring, critical reading of literature, and constructive feedback in a prescribed but individualized curriculum.

Elevated hypothalamic orexin signaling, sensitivity to orexin A, and spontaneous physical activity in obesity-resistant rats

Selectively-bred obesity-resistant [diet resistant (DR)] rats weigh less than obesity-prone [diet-induced obese (DIO)] rats, despite comparable daily caloric intake, suggesting phenotypic energy expenditure differences. Human data suggest that obesity is maintained by reduced ambulatory or spontaneous physical activity (SPA). The neuropeptide orexin A robustly stimulates SPA. We hypothesized that DR rats have greater: 1) basal SPA, 2) orexin A-induced SPA, and 3) preproorexin, orexin 1 and 2 receptor (OX1R and OX2R) mRNA, compared with DIO rats. A group of age-matched out-bred Sprague-Dawley rats were used as additional controls for the behavioral studies. DIO, DR, and Sprague-Dawley rats with dorsal-rostral lateral hypothalamic (rLHa) cannulas were injected with orexin A (0, 31.25, 62.5, 125, 250, and 500 pmol/0.5 microl). SPA and food intake were measured for 2 h after injection. Preproorexin, OX1R and OX2R mRNA in the rLHa, and whole hypothalamus were measured by real-time RT-PCR. Orexin A significantly stimulated feeding in all rats. Orexin A-induced SPA was significantly greater in DR and Sprague-Dawley rats than in DIO rats. Two-mo-old DR rats had significantly greater rLHa OX1R and OX2R mRNA than DIO rats but comparable preproorexin levels. Eight-mo-old DR rats had elevated OX1R and OX2R mRNA compared with DIO rats, although this increase was significant for OX2R only at this age. Thus DR rats show elevated basal and orexin A-induced SPA associated with increased OX1R and OX2R gene expression, suggesting that differences in orexin A signaling through OX1R and OX2R may mediate DIO and DR phenotypes.

The DDB1-CUL4ADDB2 ubiquitin ligase is deficient in xeroderma pigmentosum group E and targets histone H2A at UV-damaged DNA sites

Xeroderma pigmentosum (XP) is a heritable human disorder characterized by defects in nucleotide excision repair (NER) and the development of skin cancer. Cells from XP group E (XP-E) patients have a defect in the UV-damaged DNA-binding protein complex (UV-DDB), involved in the damage recognition step of NER. UV-DDB comprises two subunits, products of the DDB1 and DDB2 genes, respectively. Mutations in the DDB2 gene account for the underlying defect in XP-E. The UV-DDB complex is a component of the newly identified cullin 4A-based ubiquitin E3 ligase, DDB1-CUL4A(DDB2). The E3 ubiquitin ligases recognize specific substrates and mediate their ubiquitination to regulate protein activity or target proteins for degradation by the proteasomal pathway. In this study, we have addressed the role of the UV-DDB-based E3 in NER and sought a physiological substrate. We demonstrate that monoubiquitinated histone H2A in native chromatin coimmunoprecipitates with the endogenous DDB1-CUL4A(DDB2) complex in response to UV irradiation. Further, mutations in DDB2 alter the formation and binding activity of the DDB1-CUL4A(DDB2) ligase, accompanied by impaired monoubiquitination of H2A after UV treatment of XP-E cells, compared with repair-proficient cells. This finding indicates that DDB2, as the substrate receptor of the DDB1-CUL4A-based ligase, specifically targets histone H2A for monoubiquitination in a photolesion-binding-dependent manner. Given that the loss of monoubiquitinated histone H2A at the sites of UV-damaged DNA is associated with decreased global genome repair in XP-E cells, this study suggests that histone modification, mediated by the XPE factor, facilitates the initiation of NER.

Creating an infrastructure for training in the responsible conduct of research: the University of Pittsburgh's experience

In response to public concerns about the consequences of research misconduct, academic institutions have become increasingly cognizant of the need to implement comprehensive, effective training in the responsible conduct of research (RCR) for faculty, staff, students, and external collaborators. The ability to meet this imperative is challenging as universities confront declining financial resources and increasing complexity of the research enterprise. The authors describe the University of Pittsburgh's design, implementation, and evaluation of a Web-based, institution-wide RCR training program called Research and Practice Fundamentals (RPF). This project, established in 2000, was embedded in the philosophy, organizational structure, and technology developed through the Integrated Advanced Information Management Systems grant from the National Library of Medicine. Utilizing a centralized, comprehensive approach, the RPF system provides an efficient mechanism for deploying content to a large, diverse cohort of learners and supports the needs of research administrators by providing access to information about who has successfully completed the training. During its first 3 years of operation, the RPF served over 17,000 users and issued more than 38,000 training certificates. The 18 modules that are currently available address issues required by regulatory mandates and other content areas important to the research community. RPF users report high levels of satisfaction with content and ease of using the system. Future efforts must explore methods to integrate non-RCR education and training into a centralized, cohesive structure. The University of Pittsburgh's experience with the RPF demonstrates the importance of developing an infrastructure for training that is comprehensive, scalable, reliable, centralized, affordable, and sustainable.

Centrally administered orexin A increases motivation for sweet pellets in rats

RATIONALE

Centrally administered orexin A induces both feeding and locomotion in rats. Thus, the feeding response following orexin A administration may be secondary to general increases in activity rather than a specific motivation to eat.

OBJECTIVE

The aim of the study is to determine whether orexin A increases the motivation to eat.

METHODS

The effect of orexin A (0, 31.25, 62.5, 125, 250, and 500 pmol) on breakpoint was determined in male Sprague-Dawley rats with rostro-lateral hypothalamic cannulae under a progressive ratio of five schedule (PR5). The effect of orexin A (0, 31.25, 125, and 500 pmol) on pressing rate under a fixed ratio (20) schedule was obtained to analyze the time course of orexin-A-induced pressing. The effect of 24-h food deprivation on breakpoint under PR5 and the effect of orexin A (125 pmol) on free feeding (sweet pellets) and on open-field locomotor activity (0, 100, 500, and 1,000 pmol) were also tested.

RESULTS

Orexin A significantly augmented free feeding of sweet pellets, open-field locomotor activity, rate of pressing (FR20 schedule), and breakpoint (PR5 schedule), although compared to 24-h deprivation, the effect of orexin A on breakpoint was mild. However, there was a differential dose response relationship and time course of stimulation between orexin A's effects on locomotion and lever pressing.

CONCLUSION

These data indicate that infusion of orexin A enhances free feeding by enhancing and possibly prolonging motivation to eat.

The Scholarly Project Initiative: introducing scholarship in medicine through a longitudinal, mentored curricular program

Many U.S. medical schools offer students the opportunity to undertake laboratory or clinical research or another form of scholarly project over the summer months, yet few require this as a prerequisite for graduation, and even fewer provide comprehensive didactic material in preparation for the performance of such a project as an integrated component of their curricula. The authors describe the Scholarly Project Initiative of the University of Pittsburgh School of Medicine, a novel, longitudinal, and required program. The program will aim to provide all students with structured preparatory coursework, foster critical analytical and communication skills, and introduce the breadth and depth of the research and scholarly enterprise engendered by modern academic medicine in the contexts of both the classroom and an individual, mentored experience. The initiative has two goals: encouraging an interest in academic medicine in an era marked by the continuing decline in the number of physician-investigators, and fostering the development of physicians who have confidence in their abilities to practice medicine with creativity, original and analytical thought, and relentless attention to the scientific method. Planning for the Scholarly Project Initiative began officially at the University of Pittsburgh School of Medicine's Curriculum Colloquium in May 2003. The initiative was implemented with the first-year class of July 2004 as part of the new "Scientific Reasoning and Medicine" block of the School of Medicine's curriculum. The block as a whole includes traditional lectures, small-group laboratory and problem-based sessions, and mentored independent study components.

Behavioral and Neurochemical Mechanisms of the Action of Mild Stress in the Enhancement of Feeding

Rats were trained to respond under a cyclic-ratio schedule of reinforcement composed of an ascending, followed by a descending, sequence of ratio values. Subjects were trained while exposed to 70 dB white noise, then tested while exposed to 70 or 90 dB white noise. Exposure to 90 dB white noise elevated the response function (p<.02). Naloxone was then administered intraperitoneally at 0.3. 1.0. and 3.0 mg/kg under 70 dB and 90 dB white noise. Naloxone administration (1.0 and 3.0 mg/kg) significantly depressed the response function obtained under 90 dB white noise (ps<.01) but did not affect the function obtained under 70 dB white noise. These findings suggest that mild stress increases food intake through a mechanism affecting palatability enhanced by the release of endogenous opioids.

True XP group E patients have a defective UV-damaged DNA binding protein complex and mutations in DDB2 which reveal the functional domains of its p48 product

Xeroderma pigmentosum (XP) is a skin cancer-prone autosomal recessive disease characterized by inability to repair UV-induced DNA damage. The major form of XP is defective in nucleotide excision repair (NER) and comprises seven complementation groups (A-G). The genes defective in all groups have been identified unambiguously with the exception of group E. The cells of some XP-E patients are deficient in a protein complex (consisting of two subunits: p127/DDBI and p48/DDB2) which binds to UV-damaged DNA (UV-DDB) and is specifically involved in the removal of photoproducts from the non-transcribed regions of the genome. However, other XP-E patients have been reported not to lack UV-damaged DNA binding activity (DDB(+)). Here we describe several genetically unrelated XP-E patients, not previously analyzed in depth, each carrying two mutated alleles for DDB2, causing either a single amino acid change or a protein truncation or internal deletion. These defects result in a severe decrease of detectable p48 protein, abolish interaction with the p127 subunit, and produce a deficiency in UV-DDB binding activity (DDB(-)). The role of p48 in the repair defect of these patients was demonstrated in vivo and in vitro. Investigation of four DDB(+) cell strains from patients previously assigned to XP-E, allowed us to reclassify all of them into other groups and to show that they do not share the molecular and biochemical features typical for XP-E. Besides confirming that the true XP-E phenotype is DDB(-), resulting from defects in a single gene, DDB2, our results identify the functional domains of the corresponding p48 protein.

Sequential binding of UV DNA damage binding factor and degradation of the p48 subunit as early events after UV irradiation

The UV-damaged DNA binding protein complex (UV-DDB) is implicated in global genomic nucleotide excision repair (NER) in mammalian cells. The complex consists of a heterodimer of p127 and p48. UV-DDB is defective in one complementation group (XP-E) of the heritable, skin cancer-prone disorder xeroderma pigmentosum. Upon UV irradiation of primate cells, UV-DDB associates tightly with chromatin, concomitant with the loss of extractable binding activity. We report here that an early event after UV, but not ionizing, radiation is the transient dose-dependent degradation of the small subunit, p48. Treatment of human cells with the proteasomal inhibitor NIP-L3VS blocks this UV-induced degradation of p48. In XP-E cell lines with impaired UV-DDB binding, p48 is resistant to degradation. UV-mediated degradation of p48 occurs independently of the expression of p53 and the cell's proficiency for NER, but recovery of p48 levels at later times (12 h and thereafter) is dependent upon the capacity of the cell to repair non-transcribed DNA. In addition, we find that the p127 subunit of UV-DDB binds in vivo to p300, a histone acetyltransferase. The data support a functional connection between UV-DDB binding activity, proteasomal degradation of p48 and chromatin remodeling during early steps of NER.

Naloxone's effect on meal microstructure of sucrose and cornstarch diets

The opioid receptor antagonist naloxone decreases consumption of high-sucrose diets but does not reduce cornstarch diet intake in energy-restricted rats. Sucrose-fed rats eat at a much higher rate, consuming more food than cornstarch-fed rats. We examined meal microstructure using an automated weighing system in food-restricted rats eating either a high-sucrose or high-cornstarch diet. Sucrose-fed rats exhibited a higher rate of eating during their first meal compared with cornstarch-fed rats (0.34 vs. 0.20 g/min, respectively). However, naloxone did not reduce eating rate in either group. Naloxone decreased the size of the first meal in both diet groups by shortening the length of the meal. Naloxone's anorectic effect was more potent in the sucrose-fed rats. These results indicate that naloxone's heightened anorectic effect on sucrose diet consumption is not "rate dependent." Naloxone's anorectic actions may be modulated by two conditions, the sensory properties of food and the energy state of the animal. Thus the elevated anorectic potency of naloxone in energy-restricted sucrose-fed rats may reflect actions on neural systems that mediate orosensory and/or postingestive signals.