Postprocedural Cognitive Load Measurement With Immediate Feedback to Guide Curriculum Development.

BACKGROUND: Methods to assess competency in cardiothoracic training are essential. Here, we report a system that allows us to better assess competency from the perspective of both the trainee and educator. We hypothesized that postprocedural cognitive burden measurement (by the trainee) with immediate feedback (from the educator) could aid in identifying barriers to the acquisition of skills and knowledge so that training curricula can be individualized. METHODS: The National Aeronautics and Space Administration Task Load Index (NASA-TLX), a validated instrument to measure cognitive load, was administered with an online platform after bronchoscopy, esophagogastroduodenoscopy, and video-assisted thoracoscopic surgery for 11 residents. Immediate postprocedure feedback and standardized debriefing occurred for each procedure. RESULTS: Mean NASA-TLX scores were highest (indicating greater cognitive load) for esophagogastroduodenoscopy and video-assisted thoracoscopic surgery (P < .001). When comparing subscale measures, mental demand was significantly higher for video-assisted thoracoscopic surgery (P = .026) compared with the other procedures, whereas physical demand was highest for esophagogastroduodenoscopy (P = .018). Self-reported frustration was similar for all case types (P = .247). Cognitive burden decreased with a greater number of procedures for bronchoscopy (P = .027). Significant improvement was noted by the trainee at the end of the rotation in self-assessed procedural competency and preparedness for thoracic board topics (all P < .05). Postprocedure feedback by the attending surgeon correlated with more frequent completion of self-evaluations by the residents. CONCLUSIONS: Longitudinal assessment of cognitive load in combination with postprocedural feedback identified barriers to skill acquisition for both residents and educators. This information allows for individualized rotation development as a step toward a competency-based curriculum.

CaMKIV regulates mitochondrial dynamics during sepsis.

Sepsis and shock states impose mitochondrial stress, and in response, adaptive mechanisms such as fission, fusion and mitophagy are induced to eliminate damaged portions of or entire dysfunctional mitochondria. The mechanisms underlying these events are being elucidated; yet a direct link between loss of mitochondrial membrane potential ΔΨm and the initiation of fission, fusion and mitophagy remains to be well characterized. The direct association between the magnitude of the ΔΨm and the capacity for mitochondria to buffer Ca2+ renders Ca2+ uniquely suited as the signal engaging these mechanisms in circumstances of mitochondrial stress that lower the ΔΨm. Herein, we show that the calcium/calmodulin-dependent protein kinase (CaMK) IV mediates an adaptive slowing in oxidative respiration that minimizes oxidative stress in the kidneys of mice subjected to either cecal ligation and puncture (CLP) sepsis or endotoxemia. CaMKIV shifts the balance towards mitochondrial fission and away from fusion by 1) directly phosphorylating an activating Serine616 on the fission protein DRP1 and 2) reducing the expression of the fusion proteins Mfn1/2 and OPA-1. CaMKIV, through its function as a direct PINK1 kinase and regulator of Parkin expression, also enables mitophagy. These data support that CaMKIV serves as a keystone linking mitochondrial stress with the adaptive mechanisms of mitochondrial fission, fusion and mitophagy that mitigate oxidative stress in the kidneys of mice responding to sepsis.

Nitric Oxide and Endothelial Dysfunction.

Nitric oxide is a strong vasodilatory and anti-inflammatory signaling molecule that plays diverse roles in maintaining vascular homeostasis. Nitric oxide produced by endothelial cells is a critical regulator of this balance, such that endothelial dysfunction is defined as a reduced capacity for nitric oxide production and decreased nitric oxide sensitivity. This ultimately results in an imbalance in vascular homeostasis leading to a prothrombotic, proinflammatory, and less compliant blood vessel wall. Endothelial dysfunction is central in numerous pathophysiologic processes. This article reviews mechanisms governing nitric oxide production and downstream effects, highlighting the role of nitric oxide signaling in organ system pathologies.

Groin Pain Syndrome Known as Sports Hernia: A Review.

Importance: Groin pain in active individuals and athletes without clinical evidence of hernia or hip pathologic findings is challenging for health care clinicians and aggravating for those experiencing pain. Frequently called sports hernia or athletic pubalgia, many surgeons continue to refute the diagnosis because there is a lack of consensus and clear comprehension of the basic pathophysiologic features of this groin pain syndrome. Observations: Understanding the anatomic and pathophysiologic findings of groin pain syndrome is necessary to appropriately treat this problem. In general, the level of evidence of the literature is of relatively low quality. Exercise-based therapy can be an effective first-line therapy in individuals who develop groin pain syndrome. Surgical therapies are typically reserved for those who experience nonoperative management failure. The common features of the varied surgical procedures include the resultant changes in the vectors of pull on the pubic bone or joint, the defects in the inguinal canal, and the inguinal sensory nerve compression or bowstringing. Conclusions and Relevance: The diagnosis of nonhip, nonhernia, chronic groin pain is common. Understanding the diagnosis and treatment options may facilitate recovery and allow return to an active lifestyle and sport.

The Life After Surgical Residency (LASR) Curriculum for Surgical Residents: Addressing the Nonclinical Barriers to Preparedness for Independent Practice.

OBJECTIVE: Extrinsic burdens, including new personal and professional responsibilities, may distract from early career success. We sought to assess resident preparedness in nonclinical topics and to utilize this data to design a curriculum to address these content areas. DESIGN: All residents were surveyed to ascertain their self-reported preparedness on a variety of nonclinical topics (teaching, finances, contract negotiation, real estate, etc.). Using our survey results, a monthly curriculum was designed and implemented for senior residents based on these knowledge gaps. SETTING: University-based general surgery residency program. PARTICIPANTS: All general surgery residents. RESULTS: Residents reported low levels of preparedness on the topics of contract negotiation and practice management and high levels of preparedness on the topics of teaching and money management. Following curriculum implementation, statistically significant improvement was noted in the topics of contract negotiation and academic pursuits. CONCLUSIONS: Residents report low levels of preparedness in many nonclinical topics that may represent potentially modifiable stressors that can impact career success. Implementation of a directed curriculum improves sense of preparedness and may promote wellness among surgical trainees.

Sumoylation pathway is required to maintain the basal breast cancer subtype.

The TFAP2C/AP-2γ transcription factor regulates luminal breast cancer genes, and loss of TFAP2C induces epithelial-mesenchymal transition. By contrast, the highly homologous family member, TFAP2A, lacks transcriptional activity at luminal gene promoters. A detailed structure-function analysis identified that sumoylation of TFAP2A blocks its ability to induce the expression of luminal genes. Disruption of the sumoylation pathway by knockdown of sumoylation enzymes, mutation of the SUMO-target lysine of TFAP2A, or treatment with sumoylation inhibitors induced a basal-to-luminal transition, which was dependent on TFAP2A. Sumoylation inhibitors cleared the CD44(+/hi)/CD24(-/low) cell population characterizing basal cancers and inhibited tumor outgrowth of basal cancer xenografts. These findings establish a critical role for sumoylation in regulating the transcriptional mechanisms that maintain the basal cancer phenotype.

Inhibition of RET increases the efficacy of antiestrogen and is a novel treatment strategy for luminal breast cancer.

PURPOSE: Recent findings suggest that combination treatment with antiestrogen and anti-RET may offer a novel treatment strategy in a subset of patients with breast cancer. We investigated the role of RET in potentiating the effects of antiestrogen response and examined whether RET expression predicted the ability for tyrosine kinase inhibitor (TKI) to affect extracellular signal-regulated kinase 1/2 (ERK1/2) activation in primary breast cancer. EXPERIMENTAL DESIGN: Growth response, ERK1/2 activation, Ki-67, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were assessed in breast cancer cell lines in vitro and in xenografts with vandetanib and/or tamoxifen. Thirty tumors with matched normal breast tissue were evaluated for RET expression and response to TKI treatment. RESULTS: Vandetanib potentiated the inhibitory effect of tamoxifen in hormone responsive (P = 0.01) and hormone insensitive (P < 0.001) estrogen receptor α (ERα)-positive breast cancer cells. Vandetanib significantly repressed tumorigenesis of MCF-7 xenografts (P < 0.001), which displayed decreased activation of ERK1/2 and AKT. Vandetanib and tamoxifen reduced the growth of established tumors with a greater effect of dual therapy compared with single agent (P = 0.003), with tamoxifen-reducing proliferative index and vandetanib-inducing apoptosis. In primary breast cancers, RET expression correlated with the ERα-positive subtype. Relative decrease in ERK1/2 phosphorylation with TKI treatment was 42% (P < 0.001) in RET-positive tumors versus 14% (P = ns) in RET-negative tumors. CONCLUSIONS: Vandetanib potentiated the antigrowth effects of tamoxifen in breast cancer, which was mediated through RET activation. RET predicted response to TKI therapy with minimal effects on ERK1/2 activation in RET-negative tumors. The preclinical data support evaluation of antiestrogen in combination with TKI as a potential treatment strategy for RET-positive luminal breast cancer.

Complications and survival associated with operative procedures in patients with unresectable pancreatic head adenocarcinoma.

BACKGROUND: Unresectable tumors of the pancreatic head are encountered in up to 20% of patients taken for resection. The objective of this study was to evaluate the complications and outcome associated with palliative surgical procedures to help guide management decisions in these patients. METHODS: Patients with pancreatic head adenocarcinoma taken to the operating room with curative intent who did not undergo pancreatectomy were evaluated. RESULTS: From 1997 to 2013, 50 patients were explored and found be unresectable due to M1 disease (n = 27, 54.0%) or vascular invasion (n = 23, 46.0%). Among unresectable patients, 34 (68.0%) had a palliative procedure performed including double bypass (n = 13), biliary bypass (n = 7), gastrojejunostomy (n = 5), or cholecystectomy (n = 9). Complications occurred in 22 patients (44.0%), and patients who had a palliative operation had a longer hospital stay and more major complications. Overall survival was reduced in patients treated with a palliative operation. CONCLUSIONS: Despite advancements in endoscopic palliation, operative bypasses are still commonplace in patients with unresectable pancreatic head cancer. In this study, patients treated with operative procedures had a high rate of complications without a notable improvement in outcome. These findings highlight the importance of identifying unresectable disease prior to surgery and support a selective approach to palliative operations.

Distinct pathways regulated by RET and estrogen receptor in luminal breast cancer demonstrate the biological basis for combination therapy.

OBJECTIVE: We investigated directed therapy based on TFAP2C-regulated pathways to inform new therapeutic approaches for treatment of luminal breast cancer. BACKGROUND: TFAP2C regulates the expression of genes characterizing the luminal phenotype including ESR1 and RET, but pathway cross talk and potential for distinct elements have not been characterized. METHODS: Activation of extracellular signal-regulated kinases (ERK) and AKT was assessed using phosphorylation-specific Western blot. Cell proliferation was measured with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] after siRNA (small interfering RNA) gene knockdown or drug treatment. Cell cycle, Ki-67, and cleaved caspase 3 were measured by fluorescence-activated cell sorting. Tumorigenesis was assessed in mice xenografts. RESULTS: Knockdown of TFAP2C or RET inhibited GDNF (glial cell line-derived neurotrophic factor)-mediated activation of ERK and AKT in MCF-7 cells. Similarly, sunitinib, a small-molecule inhibitor of RET, blocked GDNF-mediated activation of ERK and AKT. Inhibition of RET either by gene knockdown or by treatment with sunitinib or vandetanib reduced RET-dependent growth of luminal breast cancer cells. Interestingly, knockdown of TFAP2C, which controls both ER (estrogen receptor) and RET, demonstrated a greater effect on cell growth than either RET or ER alone. Parallel experiments using treatment with tamoxifen and sunitinib confirmed the increased effectiveness of dual inhibition of the ER and RET pathways in regulating cell growth. Whereas targeting the ER pathway altered cell proliferation, as measured by Ki-67 and S-phase, anti-RET primarily increased apoptosis, as demonstrated by cleaved caspase 3 and increased TUNEL (terminal deoxyneucleotidyl transferase dUTP nick end labeling) expression in xenografts. CONCLUSIONS: ER and RET primarily function through distinct pathways regulating proliferation and cell survival, respectively. The findings inform a therapeutic approach based on combination therapy with antiestrogen and anti-RET in luminal breast cancer.

Maintenance of mitochondrial genomic integrity in the absence of manganese superoxide dismutase in mouse liver hepatocytes.

Manganese superoxide dismutase, encoded by the Sod2 gene, is a ubiquitously expressed mitochondrial antioxidant enzyme that is essential for mammalian life. Mice born with constitutive genetic knockout of Sod2 do not survive the neonatal stage, which renders the longitudinal study of the biochemical and metabolic effects of Sod2 loss difficult. However, multiple studies have demonstrated that tissue-specific knockout of Sod2 in murine liver yields no observable gross pathology or injury to the mouse. We hypothesized that Sod2 loss may have sub-pathologic effects on liver biology, including the acquisition of reactive oxygen species-mediated mitochondrial DNA mutations. To evaluate this, we established and verified a hepatocyte-specific knockout of Sod2 in C57/B6 mice using Cre-LoxP recombination technology. We utilized deep sequencing to identify possible mutations in Sod2 (-/-) mitochondrial DNA as compared to wt, and both RT-PCR and traditional biochemical assays to evaluate baseline differences in redox-sensitive pathways in Sod2 (-/-) hepatocytes. Surprisingly, no mutations in Sod2 (-/-) mitochondrial DNA were detected despite measurable increases in dihydroethidium staining in situ and concomitant decreases in complex II activity indicative of elevated superoxide in the Sod2 (-/-) hepatocytes. In contrast, numerous compensatory alterations in gene expression were identified that suggest hepatocytes have a remarkable capacity to adapt and overcome the loss of Sod2 through transcriptional means. Taken together, these results suggest that murine hepatocytes have a large reserve capacity to cope with the presence of additional mitochondrial reactive oxygen species.

Regulation of SOD2 in cancer by histone modifications and CpG methylation: closing the loop between redox biology and epigenetics.

SIGNIFICANCE: Manganese superoxide dismutase (SOD2), encoded by the nuclear gene SOD2, is a critical mitochondrial antioxidant enzyme whose activity has broad implications in health and disease. Thirty years ago, Oberley and Buettner elegantly folded SOD2 into cancer biology with the free radical theory of cancer, which was built on the observation that many human cancers had reduced SOD2 activity. In the original formulation, the loss of SOD2 in tumor cells produced a state of perpetual oxidative stress, which, in turn, drove genetic instability, leading to cancer development. RECENT ADVANCES: In the past two decades, research has established that SOD2 transcriptional activity is controlled, at least in part, via epigenetic mechanisms at different stages in the development of human cancer. These mechanisms, which include histone methylation, histone acetylation, and DNA methylation, are increasingly recognized as being aberrantly regulated in human cancer. Indeed, the epigenetic progenitor model proposed by Henikoff posits that epigenetic events are central governing agents of carcinogenesis. Important recent advances in epigenetics research have indicated that the loss of SOD activity itself may contribute to changes in epigenetic regulation, establishing a vicious cycle that drives further epigenetic instability. CRITICAL ISSUES: With these observations in mind, we propose an epigenetic revision to the free radical theory of cancer: that loss of SOD activity promotes epigenetic aberrancies, driving the epigenetic instability in tumor cells which produces broad phenotypic effects. FUTURE DIRECTIONS: The development of next-generation sequencing technologies and novel approaches in systems biology and bioinformatics promise to make testing this exciting model a reality in the near future.

Expression of the RET proto-oncogene is regulated by TFAP2C in breast cancer independent of the estrogen receptor.

BACKGROUND: The RET proto-oncogene is expressed as part of the estrogen receptor (ER) cluster in breast cancer. We sought to determine if TFAP2C regulates Ret expression directly or indirectly through ER. METHODS: Chromatin immunoprecipitation sequencing (ChIP-Seq) and gel-shift assay were used to identify TFAP2C binding sites in the RET promoter in four breast cancer cell lines. Ret mRNA and protein levels were evaluated in ER-positive and ER-negative breast cancer cell lines after knockdown of TFAP2C. Luciferase expression assay was performed to assess expression from two of the identified sites. RESULTS: ChIP-Seq identified five main binding peaks for TFAP2C in the RET promoter at -101.5 kb, -50.7 kb, -32.5 kb, +5.0 kb, and +33.6 from the RET transcriptional start site. Binding at three of the AP-2 sites was conserved across all four cell lines, whereas the RET -101.5 and RET +33.6 sites were each found to be unbound by TFAP2C in one cell line. A TFAP2C consensus element was confirmed for all five sites. Knockdown of TFAP2C by siRNA in ER-positive MCF-7 cells resulted in significant down regulation of Ret mRNA compared to nontargeting (NT) siRNA (0.09 vs. 1.0, P < 0.001). Knockdown of TFAP2C in ER-negative MDA-MB-453 cells also led to a significant reduction in Ret mRNA compared to NT siRNA (0.16 vs. 1.0, P < 0.001). In MCF-7 cells, knockdown of TFAP2C abrogated Ret protein expression (0.02 vs. 1.0, P < 0.001) before reduction in ER. CONCLUSIONS: TFAP2C regulates expression of the RET proto-oncogene through five AP-2 regulatory sites in the RET promoter. Regulation of Ret by TFAP2C occurs independently of ER expression in breast carcinoma.

The redox basis of epigenetic modifications: from mechanisms to functional consequences.

Epigenetic modifications represent mechanisms by which cells may effectively translate multiple signaling inputs into phenotypic outputs. Recent research is revealing that redox metabolism is an increasingly important determinant of epigenetic control that may have significant ramifications in both human health and disease. Numerous characterized epigenetic marks, including histone methylation, acetylation, and ADP-ribosylation, as well as DNA methylation, have direct linkages to central metabolism through critical redox intermediates such as NAD(+), S-adenosyl methionine, and 2-oxoglutarate. Fluctuations in these intermediates caused by both normal and pathologic stimuli may thus have direct effects on epigenetic signaling that lead to measurable changes in gene expression. In this comprehensive review, we present surveys of both metabolism-sensitive epigenetic enzymes and the metabolic processes that may play a role in their regulation. To close, we provide a series of clinically relevant illustrations of the communication between metabolism and epigenetics in the pathogenesis of cardiovascular disease, Alzheimer disease, cancer, and environmental toxicity. We anticipate that the regulatory mechanisms described herein will play an increasingly large role in our understanding of human health and disease as epigenetics research progresses.