Informing the surgical workforce pathway: how rural community characteristics matter

INTRODUCTION

Rural areas worldwide face a general surgeon shortage, limiting rural populations' access to surgical care. While individual and practice-related factors have been well-studied in the US, we need a better understanding of the role of community characteristics in surgeons' location choices. This study aimed to understand the deeper meanings surgeons associated with community characteristics in order to inform efforts spanning the rural surgeon workforce pathway, from early educational exposures, and undergraduate and graduate medical education, to recruitment and retention.

METHODS

We conducted a qualitative, descriptive interview study with general surgeons in the Midwestern US about the role and meaning of community characteristics, exploring their backgrounds, education, practice location choices, and future plans. We focused on rural surgeons and used an urban comparison group. We used convenience and snowball sampling, then conducted interviews in-person and via phone, and digitally recorded and professionally transcribed them. We coded inductively and continued collecting data until reaching code saturation. We used thematic network analysis to organize codes and draw conclusions.

RESULTS

A total of 37 general surgeons (22 rural and 15 urban) participated. Interviews totaled over 52 hours. Three global themes described how rural surgeons associated different, often deeper, meanings with certain community characteristics compared to their urban colleagues: physical environment symbolism, health resources' relationship to scope of practice, and implications of intense role overlap (professional and personal roles). All interviewees spoke to all three themes, but the meanings they found differed importantly between urban and rural surgeons. Physical landscapes and community infrastructure were representative of autonomy and freedom for rural surgeons. They also shared how facilities, equipment, staff, staff education, and surgical partners combined to create different scopes of practice than their urban counterparts experienced. Often, rural surgeons found these resources dictated when they needed to transfer patients to higher-acuity facilities. Rural surgeons experienced role overlap intensely, as they cared for patients who were also friends and neighbors.

CONCLUSION

Rural surgeons associated different meanings with certain community characteristics than their urban counterparts. As they work with prospective rural surgeons, educators and rural communities should highlight how health resources can translate into desired scopes of practice. They also should share with trainees the realities of role overlap, both how intense and stressful it can be but also how gratifying. Educators should include the rural social context in medical and surgical education, looking for even more opportunities to collaborate with rural communities to provide learners with firsthand experiences of rural environments, resources, and role overlap.

Recent Evolution in the Management of Lymph Node Metastases in Melanoma

Introduction

Based upon two large randomized international clinical trials (German Dermatologic Cooperative Oncology Group (DeCOG-SLT) and Multicenter Selective Lymphadenectomy Trial II (MSLT-II)) published in 2016 and 2017, respectively, active surveillance has been demonstrated to have equivalent survival outcomes to completion lymphadenectomy (CLND) for a subset of patients who have microscopic lymph node disease. In this study, the changes in national practice patterns were examined regarding the utilization of CLND after positive sentinel lymph node biopsy (SLNB).

Methods

Using the National Cancer Database, CLND utilization was examined in SLN-positive patients diagnosed with melanoma between 2012 and 2016. A hierarchal logistical regression model with hospital-level random intercepts was constructed to examine the factors associated with SLNB followed by observation vs. SLNB with CLND.

Results

Of the 148,982 patients identified, 43% (n = 63,358) underwent SLNB and 10.3% (n = 6,551) had a SLNB with microscopic disease. CLND was performed for 57% (n = 2,817) of these patients. Patients were more likely to undergo CLND if they were ≤ 55 years of age (OR, 1.454; p ≤ 0.0001), ages 56 - 65 (OR, 1.127; p = 0.026), Charlson Deyo Score = 0 (OR, 2.088; p = 0.043), or were diagnosed with melanoma in 2012 (OR, 2.259, p ≤ 0.0001).

Conclusions

The utilization of CLND among patients with microscopic nodal melanoma was significantly lower in 2016 compared to 2012. Younger age, lack of comorbidities, and primary tumor location on the trunk or head/neck were associated with higher utilization of CLND.

Morbidity and mortality of synchronous hepatectomy with cytoreductive surgery/hyperthermic intraperitoneal chemotherapy (CRS/HIPEC)

Background

Liver resection in conjunction with partial colectomy for colon cancer is considered acceptable treatment for isolated metastasis to the liver. This method is unstudied in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for carcinomatosis due to colon cancer and high grade appendiceal cancer.

Methods

A retrospective chart review included patients from 2005 to 2016 undergoing CRS/HIPEC. Cancers other than colorectal adenocarcinoma and high grade appendiceal carcinoma were excluded. Patients were divided into hepatectomy and non-hepatectomy groups. Data was collected by chart review from electronic medical records to assess morbidity and mortality, as well as oncologic outcomes of included patients.

Results

The average patient age, length of stay, and sex were similar between groups. For those in the hepatectomy group, 80% underwent minor hepatectomy, and 20% underwent major hepatectomy. The comprehensive complication index (CCI) scores ranged from 0 (no complications), to 100 (death). The average CCI between study groups was similar (27.29 vs. 17.41, P=0.09). Hepatectomy was associated with a higher rate of Clavien-Dindo classifications (CDCs) of III or greater. Complications included pressor requirement, renal failure, blood transfusions, TPN, pleural effusions and leaks requiring drain placement, respiratory failure, UTI, new onset atrial fibrillation, wound infections, and death.

Conclusions

Patients who underwent CRS/HIPEC and hepatectomy for colorectal and high grade appendiceal carcinomatosis had more severe complications at similar rates to non-hepatectomy patients. Complication rates should be considered when selecting patients for aggressive surgical intervention.

Speed Mentoring: An Innovative Method to Meet the Needs of the Young Surgeon

OBJECTIVE

Speed mentoring has recently been used by several medical organizations as a strategy to establish mentoring relationships, which are felt to be critically important in the development of the surgeon. This study assesses a surgical speed-mentoring program at the 2015 American College of Surgeons (ACS) Clinical Congress.

DESIGN

A steering committee designed the speed-mentoring program to match 60 ACS Resident and Associate Society mentees with a mix of junior and senior leadership of ACS. Each mentee met with 5 mentors for 10 minutes each during the 1 hour session. After participation in the activity, surveys were provided to assess the event. The survey included forced-choice questions using Likert-scales as well as open-ended questions. Mentor and mentee responses were compared using Medcalc software using comparison of means and comparison of proportion, with p < 0.05 considered significant.

SETTING

The study was undertaken at the 2015 ACS Clinical Congress.

PARTICIPANTS

A total of 60 mentors and 49 mentees participated in the inaugural ACS Speed-Mentoring activity. The postactivity survey was completed by 54 mentors (90%) and 39 mentees (79.5%).

RESULTS

There was a high level of satisfaction with the activity, with 100% of mentors and mentees stating that they would recommend the activity to a colleague. There was overall high satisfaction with the organization of the session by both the mentors and the mentees although the mentors were more likely to feel that they needed more time for each interaction. More mentees (93%) than mentors (68.5%) felt they were likely to develop a mentoring relationship with one of their matches outside of the organized session.

CONCLUSIONS

We demonstrated that a speed-mentoring event at a national surgical meeting offers an effective platform for mentoring and is mutually beneficial to both mentors and mentees. Data collected here will be used to modify and improve the design of future speed-mentoring sessions.

Comparison of terminal duct lobular units in the nipple areolar complex by tumor subtypes-the implication for nipple sparing mastectomy

e12082

Background: Nipple-sparing mastectomy (NSM) has gained popularity for surgical treatment of breast cancer. Terminal duct lobular units (TDLU) have been shown to be present in 25% of nipple areolar complex (NAC). Pathologic tumor subtype influence on presence of TDLU in the NAC has not been assessed. In addition, criteria for technically performing the dissection below the NAC have not been established. We sought to evaluate TDLU characteristics by tumor subtype and determine NSM dissection criteria below the NAC. Methods: A retrospective review was performed of 120 total and skin sparing mastectomies, 30 of each breast cancer subtype, from 1/2013 to 1/2015. The NAC of each mastectomy was assessed for number of TDLU and distance from TDLU to the skin. Results: Thirty of the 120 mastectomies (25%) had TDLU present below the NAC. Of the 30 with TDLU, there was no statistically significant difference in number of TDLU present based on tumor grade (gd) (gd 1 vs 2, p = .67; gd 1 vs 3, p = .24). Compared to luminal A, luminal B showed statistical significance (p < .05) for number of TDLU at the NAC whereas Her 2 and triple negative breast cancer (TNBC) were not statistically significant (p = .09 and .10). In mastectomies with TDLU present, gd 2 (p < .05) and gd 3 (p = .05) had a closer skin distance than gd 1. When compared by tumor subtype, there was no difference in TDLU to skin distance (table). Conclusions: NSM has been adopted as a safe oncologic approach to breast cancer treatment. Although presence of TDLU in luminal B subtype was statistically significant, this may not be clinically significant, as there were only 2 of 30 cases with TDLU. Our study indicates that a careful dissection at the level of the dermis below the NAC is necessary, as 25% of women will have TDLU present. This will provide an appropriate oncologic outcome similar to total and skin sparing mastectomy. Tumor subtype does not appear to be exclusion criteria for NSM. However, more aggressive dissection may be necessary to clear all TDLU from below the NAC in higher gd cancers. [Table: see text]

Abstract P4-06-01: Patient derived DCIS mouse-intraductal (MIND) models recapitulate the full spectrum of human patient pathology and histologic features including progression to invasion in a subset of cases

Introduction: The 20-year breast cancer mortality rate following a DCIS diagnosis is ∼3%. Radiation and anti-hormonal therapy of DCIS has not resulted in improved overall survival, which argues against the non-selective use of such therapies in DCIS management. However, some DCIS cases do progress to invasive cancer, and these patients may benefit from treatment. A study of 80 DCIS patients followed for up to 30 years reported a 43% progression rate. Notably, progression was not predicted by grade, as 39% of even low-grade DCIS ultimately progressed to invasive cancer. Clearly, there is a need to identify which DCIS lesions are likely to progress. We have developed a novel mouse xenograft model (mouse-intraductal; MIND) to study the molecular basis of DCIS progression and enable identification of suitable biomarkers that predict invasive progression.

Methods: MIND involves injection of epithelial cells derived from patient breast lesions into the mammary ducts of immunocompromised mice. Serial sections of mouse mammary glands containing DCIS xenograft lesions were examined at time intervals of 3-14 months post-engraftment by histology using hematoxylin and eosin (H&E) and immunohistochemistry using anti-human cytokeratin 5/19, smooth muscle actin, ER, PR, p53, Ki67 and HER-2.

Results: Intraductal injection of cells derived from breast lesions of 28 patients into 133 mice resulted in a successful engraftment rate of 60%. Among these, 12 pure DCIS samples were injected into 35 different mice to create MIND xenografts. As early as three months post-engraftment, the DCIS xenograft cells showed multilayered in situ growth consisting of atypical neoplastic cells with prominent and vesicular nuclei. DCIS MIND xenografts exhibited the full spectrum of human DCIS histologic features, including similar biomarker expression (ER, PR, Ki67, HER-2 and p53) at long-term follow-up after engraftment (up to 12 months). Most remarkably, a subset of xenografts representing 5 patients (5/12; 42%) showed progression to invasion 6-12 months post-engraftment in the absence of any external genetic manipulations. This rate is very similar to that reported for human DCIS progression in untreated patients. MIND DCIS xenograft lesions that progressed showed disruption of basement membrane and myoepithelial layer by the invasive cells, retraction of basement membrane, and micro-invasion. MIND DCIS lesions were enriched in small capillaries, and in some cases clusters of invasive cells appeared inside nearby blood vessels.

Conclusion: The MIND xenograft is a viable model for human DCIS progression that recapitulates histologic features of human DCIS, as well as reported rates of progression to invasion. The availability of this innovative model provides a valuable tool for the discovery of new biomarkers to identify DCIS with invasive potential. The identification of high risk DCIS will ultimately help patients and clinicians choose the best course of therapy and avoid the morbidity and costs associated with unnecessary treatment.

Citation Format: Behbod F, Limback D, Hong Y, Elsarraj H, Berger J, Heddens E, Valdez K, Smith WP, Inciardi M, Reddick M, Gatewood J, Darrah J, Winblad O, Meierotto R, Ricci L, Wagner J, Amin A, May L, Cusick T, Mammen J, Fields T, Godwin AK, Fabian C, Kaufman C, Tawfik O, Fan F. Patient derived DCIS mouse-intraductal (MIND) models recapitulate the full spectrum of human patient pathology and histologic features including progression to invasion in a subset of cases [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-06-01.

Characteristics in response rates for surveys administered to surgery residents

BACKGROUND

Surveys are important research tools that permit the accumulation of information from large samples that would otherwise be impractical to collect. Resident surveys have been used frequently to monitor the quality of postgraduate training. Low response rates threaten the utility of this research tool. The purpose of this study was to determine the standard response rate of surveys administered to surgery residents and identify characteristics associated with achieving greater response rates.

METHODS

A search of peer-reviewed literature published between September 2003 and June 2011 was performed with the use of PubMed with Medical Subject Headings: "internship and residency," "surgery," "data collection," and "questionnaires." For inclusion, articles must have described a survey given to active surgery residents within the United States. Surveys were evaluated based on the following criteria: population size, response rate, incentive use, follow-up use, survey format (online vs paper), and institution versus national.

RESULTS

Of 433 initial results, 47 met inclusion criteria with a mean response rate of 65.3%. Surveys administered in paper format had a greater response rate compared with those given electronically (mean 78.6% vs 36.4%, respectively, P < .001). Greatest mean response rates were seen for institutional surveys compared with those given nationally (83.1% vs 42% respectively, P < .001).

CONCLUSION

Our review demonstrated that paper surveys administered at the institutional level and during assemblies integrated into residents' schedules demonstrated enhanced response rates. The validity and generalizability of data collected through such surveys will improve as the aspects which dictate response rate are better understood and implemented.

Axillary reverse mapping: a prospective study in women with clinically node negative and node positive breast cancer

BACKGROUND

The primary aim of axillary reverse mapping (ARM) is to prevent lymphedema by preserving arm versus breast axillary lymphatics. Concerns regarding feasibility and oncologic safety have limited the adoption of the technique. This prospective study was undertaken to investigate ARM in clinically node negative and node positive breast cancer patients.

METHODS

A total of 184 patients underwent 212 ARM procedures: 155 sentinel lymph node biopsies (SLNB) without axillary lymph node dissection (ALND) (group 1) and 57 ALNDs with/without SLNB (group 2). ARM lymphatics were not preserved if they were a SLN, directly entered a SLN, or were within ALND boundaries during ALND.

RESULTS

SLN with radioisotope alone was successful in 92 % of procedures (181 of 197). ARM identification was 47 % (73 of 155) in group 1. Criteria were met in 30 % (47 of 155) for preservation, and 25 % (38 of 155) were preserved. Of those who met preservation criteria, 81 % (38 of 47) were preserved. In group 2, ARM identification was 72 % (41 of 57); 7 met criteria for preservation and were preserved. Of the ARM nodes, 10 % (22 of 212) were SLNs (crossover). ARM nodes contained metastatic disease in one crossover and two nonsentinel ARM nodes in clinically node positive patients with N2/N3 disease.

CONCLUSIONS

ARM is a feasible technique for identification and preservation of axillary arm lymphatics with an acceptable incidence of SLN crossover. A larger sample size is needed to determine if ARM can reduce the incidence of lymphedema in patients undergoing SLNB alone and to confirm the absence of ARM metastases in clinically node negative patients undergoing ALND.

Prospective evaluation of BRCA mutations in a large triple-negative breast cancer (TNBC) registry: Implications for germline testing

1026

Background: Although current NCCN guidelines recommend genetic testing (GT) for all TNBC patients aged <60 years (regardless of family history) however due to the lack of prospective information on prevalence of mutations in unselected TNBC patients, these guidelines have not been widely adopted by clinicians and insurance carriers (including Medicare). Data on BRCA mutations from unselected TNBC cohorts are lacking. Aims: In a large TNBC registry, to prospectively determine the 1) prevalence of germline BRCA mutations and 2) validity of current NCCN guidelines for GT. Methods: Patients with stage I-III TNBC presenting for treatment at an academic and surrounding community practices were approached for participation in a prospective registry. All patients underwent comprehensive BRACAnalysis (Myriad). Detailed FH was collected. Mutation prevalence in the entire cohort and in subgroups stratified by FH and age were calculated. A significant family history (SFH) was defined as 1st-/2nd-degree relatives with breast cancer aged <50 years or ovarian cancer at any age. Results: 165 patients with stage I-III TNBC have been enrolled from 2011-2013. Median age 54 (range 24-84yrs), 58% postmenopausal, 29% LN +, 33%, 58% and 9% had stage I, II, III disease respectively. 82% Caucasian, 14% AA, 2% Hispanic, 0.6% Ashkenazi Jewish. Deleterious BRCA1/2 mutations were identified in 13.1% patients (20/152, 15 BRCA1, 5 BRCA2; results pending in 13). 27% of patients had a SFH and 64% had any FH. Mutation rates in patients with or without SFH was 32.5% and 6.1%, respectively. When examined by age at diagnosis, the mutation rates were: 16.6% (<60yrs), 21.8% (<50yrs), 10.6% (51-60yrs), and 0% (>60 yrs). If SFH or age <50, were the only criteria used 35% and 30% of mutations would have been missed. All mutations were identified using the NCCN guidelines. Conclusions: This is the first study to prospectively evaluate BRCA mutations in an unselected TNBC cohort. In this large academic and community registry with negligible Ashkenazi representation, the overall BRCA mutation rate was 13%; 16.6% in those <60 years. These results validate GT based on current NCCN guidelines and support its use in routine clinical practice.

Low grade B cell lymphoma arising in a background of multifocal extra-adrenal myelolipoma

Myelolipomas are rare, benign, non-functioning tumors composed of an admixture of mature adipose tissue and hematopoietic elements. Extra-adrenal myelolipomas are extremely rare, but have been reported in multiple sites including the omentum, presacral, and retroperitoneal areas, along with the thorax, kidneys, liver and stomach. We report a case of a 68-year-old man with low-grade B-cell lymphoma arising in a background of recurrent multifocal extra-adrenal myelolipoma. Pathological evaluation of the lesion and bone marrow showed foci of lymphoid aggregate that were confirmed to be monoclonal B lymphoma by flow cytometry. To our knowledge, this is only the third reported case to feature such a rare combination of diseases. The clinical, radiological, and pathological differential diagnostic findings are discussed.

Secondary review of external histopathology on cutaneous oncology patients referred for sentinel lymph node biopsy: how often does it happen and is it worth it?

BACKGROUND

We reviewed the data on external histopathology review for patients referred to our institution for sentinel lymph node biopsy (SLNB) associated with melanoma, Merkel cell carcinoma and adnexal carcinoma.

METHODS

We calculated the incidence of external histopathology review and the rate of discordance between internal and external histopathology diagnoses between January 1, 2010 and February 28, 2011. We conducted an anonymous poll of our community pathologists' experience with external histopathology review prior to SLNB. Financial charges and payments from 10 Medicare patients who underwent SLNB were obtained from our hospital's finance department.

RESULTS

Sixty-eight cases were identified (63 melanomas, 4 Merkel cell carcinomas and 1 spiradenocarcinoma). The external histopathology was reviewed as part of the patient's care in 14 of 68 cases. In 3 of 14 reviewed cases, SLNB was deemed unnecessary. Nine of eleven community pathologists reported reviewing external histopathology material in less than 11% SLNB patients in their hospitals. The average Medicare reimbursement for SLNB and secondary pathology review was $5738 and $80 respectively.

CONCLUSIONS

Our data show that review of external cutaneous histopathology diagnoses on patients referred for SLNB is uncommon in our practice area, but is cost-effective and should be required to reduce unnecessary treatment.

Underlying prothrombotic states in pregnancy associated cerebral venous thrombosis

BACKGROUND

The exact pathogenesis of pregnancy associated cerebral venous thrombois is still unsettled. Aims : To identify possible inherited and acquired prothrombotic risk factors and also identify the factors associated with mortality in pregnancy associated CVT.

SETTINGS AND DESIGN

Prospective cohort study to identify prothrombotic risk factors and case control study of influence of local traditional practice of puerperal water restriction on postpartum CVT.

MATERIALS AND METHODS

Consecutive patients with pregnancy associated CVT seen over a period of three years. Thrombotic workup included genetic markers, protein assays, and other factors.

STATISTICAL ANALYSIS

Univariate and chi-square analysis.

RESULTS

Of the 41 patients studied during the study period, 71% of patient had a single and 34% had multiple prothrombotic risk factors. Methylene tetrahydro-folate reductase (MTHFR) heterozygosity (19.5%) and factor V Leiden heterozygous (7.3%) were the commonest genetic markers. Hyperhomocysteinemia (34%) and elevated factor VIII levels (14.6%) were the other important risk factors. In this cohort the mortality was 17%. Mortality increased by odds of 1.3 for every additional prothrombotic marker. The factors associated with increased mortality included: status epileptics (P = 0.05, OR 13.2, 95% CI 1.002 - 173), deep venous system involvement (P = 0.016, OR 9.64, 95% CI 1.53 - 60.6), presence of midline shift (P = 0.012, OR 24.7, 95% CI 2.05 - 29.8) and diffuse cerebral edema (P = 0.006, OR 14.5, 95% CI 2.18- 96.4). The traditional practice of decrease intake of water during puerperium was significant in woman with pregnancy associated CVT when compared to control subjects (P < 0.02).

CONCLUSION

In patients with pregnancy associated CVT, prothrombotic markers can be multiple and are associated with increased odds of mortality. Deep venous system involvement, presence of midline shift and diffuse cerebral edema increased mortality. Peuperial water restriction may be a modifiable risk factor.

Achieving and maintaining quality in the laboratory

In order to ensure the delivery of a service of the highest possible quality, it is an essential requirement that laboratories undertake strict internal quality control (QC) measures as well as participate in external quality assessment (EQA) schemes. For any given test, a critical part of the internal QC process involves the establishment of reference intervals using samples taken from normal individuals, and then calculating limits representing the 95% range. This forms the basis for assessment of abnormal test results, which will in turn impact on laboratory performance in proficiency testing exercises in EQA programmes. Whereas for plasma-based assay systems, variability in performance in EQA exercises is usually determined by measurement of a coefficient of variation (CV), results of genetic testing is usually measured in absolute terms. Despite this, results of genetic EQA programmes confirm that errors in testing do occur, as much because of inadvertent sample switching and transcription errors as to analytical mistakes. EQA programmes involving identification of mutations by DNA sequencing, such as haemophilia, is made difficult by the high information content of sequence data. Nevertheless, results show that errors are usually made in the naming of the mutations, indicating that this is an evolving and poorly standardized area. Developing countries face particular challenges in the encouragement of laboratories to participate in local EQA programmes, as well as in relation to the logistical issues of sample provision, distribution and result collation in an effective and affordable manner.

Pre-transplant reduction of isohaemagglutinin titres by donor group plasma infusion does not reduce the incidence of pure red cell aplasia in major ABO-mismatched transplants

Major ABO incompatibility in stem cell transplant recipients has been associated with pure red cell aplasia (PRCA). Reduction of incompatible isohaemagglutinin titres pre-transplant by various methods has been thought to reduce the incidence of PRCA. Our data suggest that pre-transplant reduction of incompatible isohaemagglutinin titres by donor group plasma infusion does not reduce the incidence of PRCA. We also failed to find any relationship between pre-transplant ABO isohaemagglutinin titre and the risk of developing PRCA.

Expression and activity of C/EBPbeta and delta are upregulated by dexamethasone in skeletal muscle

The influence of glucocorticoids on the expression and activity of the transcription factors CCAAT/enhancer binding protein (C/EBP)beta and delta in skeletal muscle was examined by treating rats or cultured L6 myotubes with dexamethasone. Treatment of rats with 10 mg/kg of dexamethasone resulted in increased C/EBPbeta and delta DNA binding activity in the extensor digitorum longus muscle as determined by electrophoretic mobility shift assay (EMSA) and supershift analysis. A similar response was noticed in dexamethasone-treated myotubes. In other experiments, myocytes were transfected with a plasmid containing a promoter construct consisting of multiple C/EBP binding elements upstream of a luciferase reporter gene. Treatment of these cells with dexamethasone resulted in a fourfold increase in luciferase activity, suggesting that glucocorticoids increase C/EBP-dependent gene activation in muscle cells. In addition, dexamethasone upregulated the protein and gene expression of C/EBPbeta and delta in the myotubes in a time- and dose-dependent fashion as determined by Western blotting and real-time PCR, respectively. The results suggest that glucocorticoids increase C/EBPbeta and delta activity and expression through a direct effect in skeletal muscle.

Bryostatin-1 enhances barrier function in T84 epithelia through PKC-dependent regulation of tight junction proteins

Protein kinase C (PKC) is known to regulate epithelial barrier function. However, the effect of specific PKC isozymes, and their mechanism of action, are largely unknown. We determined that the nonphorbol ester PKC agonist bryostatin-1 increased transepithelial electrical resistance (TER), a marker of barrier function, in confluent T84 epithelia. Bryostatin-1, which has been shown to selectively activate PKC-alpha, -epsilon, and -delta (34), was associated with a shift in the subcellular distribution of the tight junction proteins claudin-1 and ZO-2 from a detergent-soluble fraction into a detergent-insoluble fraction. Bryostatin-1 also led to the appearance of a higher-molecular-weight form of occludin previously shown to correspond to protein phosphorylation. These changes were attenuated by the conventional and novel PKC inhibitor Gö-6850 but not the conventional PKC inhibitor Gö-6976 or the PKC-delta inhibitor röttlerin, implicating a novel isozyme, likely PKC-epsilon. The results suggest that enhanced epithelial barrier function induced by bryostatin-1 involves a PKC-epsilon-dependent signaling pathway leading to recruitment of claudin-1 and ZO-2, and phosphorylation of occludin, into the tight junctional complex.

Bryostatin-1 attenuates TNF-induced epithelial barrier dysfunction: role of novel PKC isozymes

Tumor necrosis factor (TNF) increases epithelial permeability in many model systems. Protein kinase C (PKC) isozymes regulate epithelial barrier function and alter ligand-receptor interactions. We sought to define the impact of PKC on TNF-induced barrier dysfunction in T84 intestinal epithelia. TNF induced a dose- and time-dependent fall in transepithelial electrical resistance (TER) and an increase in [(3)H]mannitol flux. The TNF-induced fall in TER was not PKC mediated but was prevented by pretreatment with bryostatin-1, a PKC agonist. As demonstrated by a pattern of sensitivity to pharmacological inhibitors of PKC, this epithelial barrier preservation was mediated by novel PKC isozymes. Bryostatin-1 reduced TNF receptor (TNF-R1) surface availability, as demonstrated by radiolabeled TNF binding and cell surface biotinylation assays, and increased TNF-R1 receptor shedding. The pattern of sensitivity to isozyme-selective PKC inhibitors suggested that these effects were mediated by activation of PKC-epsilon. In addition, after bryostatin-1 treatment, PKC-delta and TNF-R1 became associated, as determined by mutual coimmunoprecipitation assay, which has been shown to lead to receptor desensitization in neutrophils. TNF-induced barrier dysfunction occurs independently of PKC, but selective modulation of novel PKC isozymes may regulate TNF-R1 signaling.

Molecular regulation of muscle cachexia: it may be more than the proteasome

Muscle cachexia induced by sepsis, severe injury, cancer, and a number of other catabolic conditions is mainly caused by increased protein degradation, in particular breakdown of myofibrillar proteins. Ubiquitin-proteasome-dependent proteolysis is the predominant mechanism of muscle protein loss in these conditions, but there is evidence that several other regulatory mechanisms may be important as well. Some of those mechanisms are reviewed in this article and they include pre-, para-, and postproteasomal mechanisms. Among preproteasomal mechanisms, mediators, receptor binding, signaling pathways, activation of transcription factors, and modification of proteins are important. Several paraproteasomal mechanisms may influence the trafficking of ubiquitinated proteins and their interaction with the proteasome, including the expression and activity of the COP9 signalosome, the carboxy terminus of heat shock protein 70-interacting protein (CHIP) and valosin-containing protein (VCP). Finally, because the proteasome does not degrade proteins completely into free amino acids but into peptides, postproteasomal degradation of peptides by the giant protease tripeptidyl peptidase II (TPP II) and various aminopeptidases is important in muscle catabolism. Thus, multiple mechanisms and regulatory steps may influence the breakdown of ubiquitinated muscle proteins by the 26S proteasome.

Total synthesis of the calphostins: application of fischer carbene complexes and thermodynamic control of atropisomers

The total syntheses of the potent protein kinase C inhibitors calphostins A, B, C, and D as well as a variety of structural analogues are reported. An aminobenzannulation reaction of an enantiopure chromium Fischer carbene complex is utilized to prepare a pentasubstituted naphthylamine. After optimization of side-chain substituents, conversion of the naphthylamine to an o-naphthoquinone was followed by biomimetic oxidative dimerization using trifluoroacetic acid and air yielding a 1:2 P/M mixture of atropisomeric perylenequinones. Thermal equilibration to a 3:1 P:M atropisomeric ratio and separation of the perylenequinones followed by side chain desymmetrization and functionalization led to the total synthesis of enantio- and diastereomerically pure calphostin C in only twelve steps from commercially available starting materials. In addition, calphostins A, B, D, and several structural analogues were prepared to evaluate biological activities.