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Biomedical subjects

Stanley W Ashley

Publications and source records attributed to Stanley W Ashley.

At least 19 recordsLinked to original sources

Resistance to change in surgical residency: an ethnographic study of work hours reform.

BACKGROUND: Although the practical challenges to work hour restrictions have been the focus of much discussion, cultural resistance to such change has received less attention. Surgical residency has its own unique social structure, and we hypothesized that challenges to this would provide impediments to successful implementation of duty hours reform. STUDY DESIGN: We used ethnographic research methods to study the efforts at work hour restriction over a 15-month period before the introduction of the Accreditation Council for Graduate Medical Education regulations. These methods, validated for studying institutional change, build on intense periods of observation. Records of observations are then analyzed and coded to uncover cultural and political challenges. The frequency of successful hand-offs in sign-out situations between day and night float residents was measured as an objective index of success. RESULTS: Practical issues were addressed initially by scheduling adjustments including creating a night float system. The hand-offs that this system required, however, were successful only 14% of the time. Subsequent steps to address the challenge to resident identity by top-down support of a new definition of professionalism increased the number of successful hand-offs to 39%. Finally, a reduction in a noted hierarchy violation led to successful hand-offs 79% of the time. CONCLUSIONS: These results demonstrate that practical solutions alone may not be a sufficient basis for change in surgical residency. While we face other challenges to the traditional surgical culture, attention to social and political issues may enhance the success of our efforts.

Boston↗

Bouveret meets Boerhaave.

Rarely, biliary-enteric fistula can result in duodenal obstruction or Bouveret's syndrome. Boerhaave's syndrome is a distal esophageal rupture in the setting of severe emesis. This case is the first reported successful management of these clinical scenarios occurring simultaneously and highlights important features in presentation, diagnosis, and surgical treatment.

Aged, 80 and over↗

Lentivirus-mediated RNA interference of HMGA1 promotes chemosensitivity to gemcitabine in pancreatic adenocarcinoma.

The high mobility group A1 (HMGA1) proteins are overexpressed in pancreatic cancers. They are architectural nuclear proteins, which regulate expression of multiple genes implicated in the malignant phenotype. In this study, we hypothesized that HMG A1 silencing will promote chemosensitivity in pancreatic adenocarcinoma. We studied highly malignant pancreatic adenocarcinoma cell lines (MiaPaCa2 and PANC1). Lentiviral short-hairpin RNA (shHMGA1) expression vectors targeting HMGA1 were used for generation of lentiviral particles. Stable transfectants were developed after lentiviral transduction. Nuclear expression of HMGA1 was assayed using Western blot analysis. Chemosensitivity to gemcitabine was determined by IC50 analysis. Caspase activity was quantitated using fluorometric caspase profiling. Apoptosis was assessed by flow cytometric analysis. Lentivirus-mediated RNA interference resulted in 90% silencing of HMGA1 expression in each of MiaPaCa2 and PANC1 cell lines. HMGA1 silencing enhanced chemosensitivity to gemcitabine with an approximately 50% reduction in IC50 in each cell line. Lentivirus-mediated HMGA1 silencing promoted the activation of caspases 3, 2, 9, and 8, on exposure to gemcitabine. HMGA1 silencing resulted in reduction in Akt kinase activity. Lentivirus-mediated RNA interference of HMGA1 promoted chemosensitivity to gemcitabine in pancreatic adenocarcinoma. HMGA1 may represent a novel therapeutic target in pancreatic cancer.

Antimetabolites, Antineoplastic↗

Carcinoid tumors.

Explore the source record for details and available documents.

Antineoplastic Agents↗

Endoscopic treatment for atypical manifestations of gastroesophageal reflux disease.

OBJECTIVES: Atypical manifestations are common in patients with gastroesophageal reflux disease (GERD). The aim of this study was to evaluate the response of atypical manifestations of GERD to endoscopic antireflux treatment. METHODS: Patients with atypical manifestations of GERD including hoarseness, cough, wheezing, and non-cardiac chest pain were studied. Endoscopic antireflux treatment consisted of placement of sutures below the squamo-columnar junction. Clinical response was defined as complete resolution of the atypical symptom. Patients were followed clinically for up to 3 yr after the procedure. Short-term response was evaluated within 6 months of the procedure, and long-term follow-up was determined 1-3 yr after the procedure. RESULTS: Forty-three patients met the inclusion criteria; four patients underwent repeat procedures during the study period and were excluded from the analysis. Long-term follow-up was available in all 39 patients. Short-term response counts were: hoarseness, 12 of 19 patients, cough, 17 of 19; wheezing, 8 of 9; and chest pain, 13 of 18. Long-term follow-up of patients (mean of 18 months) for these symptoms was not significantly different compared to short-term response. CONCLUSIONS: Endoscopic suturing of the gastroesophageal junction appears to be a possible treatment option for atypical manifestations of GERD and future studies are needed to determine its role in management.

Adult↗

Differential role of vagus nerve in maintaining diurnal gene expression rhythms in the proximal small intestine.

BACKGROUND: We have documented previously diurnal rhythms in intestinal sugar transporter expression. We set out to identify the role of the vagus nerve in these rhythms. MATERIALS AND METHODS: Sprague-Dawley rats underwent truncal vagotomy (V; n = 9) and were pair-fed with sham-operated (n = 4) and unoperated rats (n = 6). Rats were killed at ZT3 and ZT9 (ZT: Zeitgeber time with ZT0 set at lights-on), the time interval over which sucrase, SGLT1, GLUT2, and GLUT5 expression exhibit significant anticipatory increases. Jejunal RNA expression for the four genes were assessed by Northern blot analysis. SGLT1 and GLUT2 expression was further studied by Western blot analysis and in situ hybridization. RESULTS: Control rats (sham-operated plus unoperated rats) exhibited the expected increase in RNA levels at ZT9 versus ZT3 for SGLT1, GLUT2, GLUT5, and sucrase (P < 0.01 for each). The diurnal rhythm of mRNA levels for GLUT2 and sucrase, but not for SGLT1 or GLUT5, were blunted in V rats. At protein level, SGLT1 was induced 4.3-fold in control rats (P < 0.01) and 3.8-fold in V rats (P < 0.01), whereas GLUT2 was induced 3.3-fold in control rats (P < 0.01) but only 1.4-fold in V rats (N.S.). CONCLUSIONS: Our results indicate that signaling through the vagus nerve is necessary for the anticipatory induction of GLUT2 and sucrase. Persistence of normal rhythms in both SGLT1 and GLUT5 indicates that diurnal induction of these genes is independent of vagal innervation. Entrainment of anticipatory diurnal gene expression in the intestine occurs via two separate pathways that are differentially dependent on vagal input.

Animals↗

RNA interference: a mammalian SID-1 homologue enhances siRNA uptake and gene silencing efficacy in human cells.

SID-1 is a transmembrane protein that mediates systemic RNA interference in Caenorhabditis elegans. Here we show that the mammalian SID-1 homologue FLJ20174 localizes to the cell membrane of human cells and enhances their uptake of small interfering RNA (siRNA), resulting in increased siRNA-mediated gene silencing efficacy. This is the first demonstration to show that overexpression of a membrane protein enhances siRNA internalization in mammalian cells. This observation raises the possibility of enhancing the efficacy of RNA interference.

Adenosine Triphosphate↗

RNA interference demonstrates a novel role for integrin-linked kinase as a determinant of pancreatic adenocarcinoma cell gemcitabine chemoresistance.

Integrin-linked kinase (ILK) facilitates signal transduction between extracellular events and important intracellular survival pathways involving protein kinase B/Akt. We examined the role of ILK in determining pancreatic adenocarcinoma cellular chemoresistance to the nucleoside analogue gemcitabine. Cellular ILK expression was quantified by Western blot analysis. We examined the effects of overexpression of active ILK and of ILK knockdown induced by RNA interference on gemcitabine chemoresistance. We also examined the effects of modulating ILK expression on gemcitabine-induced caspase 3-mediated apoptosis, phosphorylation status of Akt (Ser473) and glycogen synthase kinase. Overexpression of ILK increased cellular gemcitabine chemoresistance, whereas ILK knockdown induced chemosensitization via increased caspase 3-mediated apoptosis. ILK knockdown attenuated Akt Ser473 and glycogen synthase kinase phosphorylation, whereas overexpression of constitutively active myristoylated Akt was sufficient to induce significant recovery in gemcitabine chemoresistance in the presence of ILK knockdown. Levels of ILK expression affect gemcitabine chemoresistance in pancreatic adenocarcinoma cells. This novel finding suggests that therapies directed against ILK and its downstream signaling targets may have the potential to enhance the efficacy of gemcitabine-based chemotherapy.

Adenocarcinoma↗

Risk factors and outcomes of pancreatitis after open heart surgery.

BACKGROUND: We sought to analyze the risk factors and natural history associated with post-cardiac surgery acute pancreatitis. METHODS: Retrospective analysis of all patients having undergone cardiac surgery at our hospital between January 1, 1992, and October 1, 2001. RESULTS: A total of 10,249 cardiac operations were performed. Thirty-nine (0.4%) patients developed postoperative pancreatitis. There was a higher incidence during the period spanning 1992 through 1996 than 1997 through 2001 (0.6% versus 0.2%, P< .05). Patients with pancreatitis had longer postoperative length of stay (51+/-5 days versus 10+/-1 days, P<.05) and a greater in-hospital mortality rate (28% versus 4%, P<.05) than patients who did not develop pancreatitis. A history of alcohol abuse, cardiac surgery performed during 1992 to 1996, increased cardiopulmonary bypass time, and increased cross-clamp time were independent risk factors for the development of pancreatitis. Multiple-organ failure was an independent predictor for death among patients with pancreatitis. CONCLUSIONS: Although the frequency of post-cardiac surgery pancreatitis is diminishing, it is still associated with significant mortality.

Acute Disease↗

Surgical residents' perceptions of the effects of the ACGME duty hour requirements 1 year after implementation.

BACKGROUND: In July 2003, the Accreditation Council for Graduate Medical Education implemented nationwide requirements on resident duty hours with the aim of improving quality of care. Our objectives were (1) to determine the extent and means of compliance with the ACGME requirements within general surgery residency programs and (2) to examine general surgery residents' perceptions of the effects of the ACGME requirements on patient care and residents' training experience. METHODS: A survey was mailed to residents in 19 New England general surgery programs in spring 2004 (n=238). RESULTS: The overall response rate was 36%. More than 89% of respondents reported that the requirements generally were being enforced, and respondents' mean work hours (80.8 +/- 11.7 per week) supported this claim. Forty-three percent felt that quality of care had deteriorated. Although 70% perceived decrements in continuity of care, only 32% believed that the risk of patient management errors had increased. Sixty percent reported doing fewer operations, and half felt that residents missed out on too many learning opportunities. Yet, only 39% reported that the requirements had worsened the quality of training. Residents consistently reported an improved quality of life. Seventy-five percent felt that, overall, the requirements were a good thing. CONCLUSIONS: Most surgical residents do not believe that the ACGME duty hour requirements have had their intended effect of improving quality of care and are ambivalent about effects on the quality of their training. However, they report an improved quality of life, and most residents do support the requirements overall.

Adult↗

CEACAM6 is a novel biomarker in pancreatic adenocarcinoma and PanIN lesions.

OBJECTIVE: The purpose of this study was to test the hypothesis that CEACAM6 expression is an indicator of adverse pathologic features and clinical outcome in pancreatic adenocarcinoma. SUMMARY BACKGROUND DATA: Previously, we have demonstrated carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) to be an oncoprotein that plays an important role in the biology of pancreatic adenocarcinoma. Suppression of CEACAM6 expression reduces tumorigenesis and metastasis in vivo. METHODS: A tissue microarray was constructed using tumor specimens obtained from 89 consecutive patients who had undergone pancreatic resection for pancreatic adenocarcinoma with curative intent. A second microarray containing 54 pancreatic intraepithelial neoplasia (PanIN) lesions was constructed using tissues from a separate cohort of 44 patients. Both arrays were immunostained using a specific anti-CEACAM6 monoclonal antibody. Tumoral CEACAM6 expression was dichotomized into negative and positive immunoreactivity groups. The log-rank test was used to evaluate univariate associations of CEACAM6 expression with prognosis. Survival curves were derived using the Kaplan-Meier method. RESULTS: Tumoral CEACAM6 expression was detected in 82 (92%) pancreatic adenocarcinoma specimens. CEACAM6 expression was more prevalent in high-grade than in low-grade PanIN lesions (P = 0.0002). Negative tumoral CEACAM6 expression was associated with absence of lymph node metastases (P = 0.012), lower disease stage (P = 0.008), and longer postoperative survival (P = 0.047). CONCLUSIONS: CEACAM6 is a novel biomarker for pancreatic adenocarcinoma. CEACAM6 warrants further evaluation as both a prognostic factor and a therapeutic target in pancreatic cancer.

Adenocarcinoma↗

RETRACTED: Prostaglandin E2 enhances pancreatic cancer invasiveness through an Ets-1-dependent induction of matrix metalloproteinase-2.

Accumulating evidence suggests an important role for cyclooxygenase-2 (COX-2) in the pathogenesis of a wide range of malignancies. Here we tested the hypothesis that the COX-2 product prostaglandin E(2) (PGE(2)) increases cellular invasive potential by inducing matrix metalloproteinase-2 (MMP-2) expression and activity through an extracellular signal-regulated kinase (ERK)/Ets-1-dependent mechanism in pancreatic cancer. PANC-1 and MIAPaCa-2 pancreatic cancer cells were treated with PGE(2) or rofecoxib, a selective COX-2 inhibitor. MMP-2 expression and activity were assayed using Western blot analysis and zymography, respectively. MMP-2 promoter activity was analyzed with a luciferase-based assay. Ets-1 activity was analyzed using gel shift assay. Ets-1 expression was specifically silenced using RNA interference. Cellular invasive and migratory potentials were determined using a Boyden chamber assay with or without Matrigel, respectively. Exogenous PGE(2) induced MMP-2 expression and activity and increased ERK1/2 phosphorylation, Ets-1 binding activity, and MMP-2 promoter activity. PGE(2) also increased cellular migratory and invasive potentials. The mitogen-activated protein kinase kinase inhibitor PD98059 and Ets-1 silencing each abolished PGE(2)-induced increases in MMP-2 expression. PD98059 and Ets-1 silencing each abrogated the effect of PGE(2) on cellular invasive potential but not on cellular migratory potential. Rofecoxib suppressed MMP-2 expression and activity, Ets-1 binding activity, MMP-2 promoter activity, and cellular migratory and invasive potentials. These results suggest that PGE(2) mediates pancreatic cancer cellular invasiveness through an ERK/Ets-1-dependent induction of MMP-2 expression and activity. They also suggest that COX-2 inhibition may represent a strategy to inhibit invasive potential in pancreatic cancer.

Cell Line, Tumor↗

Ligation of EphA2 by Ephrin A1-Fc inhibits pancreatic adenocarcinoma cellular invasiveness.

The Eph tyrosine kinases interact with ligands of the Ephrin family and have diverse cellular functions. EphA2 has been recognized to be an oncoprotein of importance in a range of cancers. Here, we examine the effect of EphA2 overexpression and ligation by chimeric Ephrin A1-Fc on the invasive phenotype of pancreatic adenocarcinoma cells. We show that EphA2 overexpression induces a FAK-dependent increase in MMP-2 expression and invasiveness. EphA2 ligation induces proteosomal degradation of EphA2, attenuates the invasive phenotype, and decreases both FAK phosphorylation and MMP-2 expression. EphA2 appears to represent a rational therapeutic target and ligation by Ephrin A1-Fc is one strategy to modulate levels of this oncoprotein.

Adenocarcinoma↗

Overexpression of CEACAM6 promotes insulin-like growth factor I-induced pancreatic adenocarcinoma cellular invasiveness.

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a glycosylphosphatidylinositol-linked immunoglobulin superfamily member that is overexpressed in a variety of human cancers. We have recently reported that suppression of CEACAM6 expression impairs pancreatic adenocarcinoma progression in vivo. In order to characterize the mechanisms through which CEACAM6 influences the malignant phenotype, CEACAM6-overexpressing Capan2 pancreatic adenocarcinoma cells were established by stable transfection. We determined the effect of CEACAM6 overexpression on cellular invasiveness towards insulin-like growth factor I (IGF-I), a peptide of critical importance in pancreatic cancer malignant cellular behavior and tumor progression. IGF-I-induced cellular invasiveness and IGF-IR expression were significantly increased in clones overexpressing CEACAM6. Using inhibitory anti-IGF-IR antibody, a requirement for IGF-IR signaling in the enhanced invasiveness towards IGF-I induced by CEACAM6 overexpression was confirmed. CEACAM6-overexpressing clones exhibited increased Akt and c-Src kinase activities, as well as higher levels of matrix metalloproteinase-2 (MMP-2) expression and activity in the presence of IGF-I. While Akt kinase is both necessary and sufficient to induce IGF-IR upregulation, c-Src kinase activity is necessary, but alone is insufficient to upregulate IGF-IR expression. CEACAM6 is an important determinant of pancreatic adenocarcinoma malignant cellular behavior and, together with its downstream targets, warrants further investigation as a therapeutic target in this disease.

Adenocarcinoma↗

A novel role for carcinoembryonic antigen-related cell adhesion molecule 6 as a determinant of gemcitabine chemoresistance in pancreatic adenocarcinoma cells.

Most patients with pancreatic adenocarcinoma present with surgically incurable disease. Gemcitabine, the principal agent used to treat such patients, has little impact on outcome. Overexpression of carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 6, a feature of this malignancy, is associated with resistance to anoikis and increased metastasis. The purpose of this study was to determine the role of CEACAM6 in cellular chemoresistance to gemcitabine. CEACAM6 was stably overexpressed in Capan2 cells, which inherently express very low levels of the protein. Suppression of CEACAM6 expression was achieved in BxPC3 cells, which inherently overexpress CEACAM6, by stable transfection of a CEACAM6 small interfering RNA-generating vector. The effects of modulating CEACAM6 expression on gemcitabine-induced cytotoxicity were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assay, flow cytometric apoptosis quantification, caspase profiling, and Western analysis of cytoplasmic cytochrome c release. The roles of Akt and c-Src kinases as downstream targets of CEACAM6 signaling were examined. Stable overexpression of CEACAM6 in Capan2 increased gemcitabine chemoresistance, whereas CEACAM6 gene silencing in BxPC3 markedly increased the sensitivity of these cells to gemcitabine. Differential expression of CEACAM6 modulates Akt activity in a c-Src-dependent manner, and CEACAM6 overexpression appears to protect cells from cytochrome c-induced caspase 3 activation and apoptosis.

Adenocarcinoma↗

Fibronectin-induced COX-2 mediates MMP-2 expression and invasiveness of rhabdomyosarcoma.

Although accumulating evidence suggests the importance of cyclooxygenase-2 (COX-2) and prostaglandin E(2) (PGE(2)) in the pathogenesis of many cancers, the mechanism by which this enzyme and its metabolite promote cancer progression is unknown. In this study, we investigated the role of COX-2 in fibronectin-induced up-regulation of rhabdomyosarcoma matrix metalloproteinase (MMP)-2 activity and cellular invasiveness. We tested three human rhabdomyosarcoma cell lines: RMS559, RD, and SJRH30. Cell attachment to fibronectin up-regulated both COX-2 expression and PGE(2) production and concomitantly enhanced MMP-2 activity. Exogenous PGE(2) stimulated MMP-2 promoter activity, increased MMP-2 expression, and increased cellular invasiveness. Aspirin and rofecoxib (non-selective and selective COX-2 inhibitor, respectively) each abolished fibronectin-associated induction of MMP-2 and induced dose-dependent reductions in cellular invasiveness. These data implicated a role for inducible COX-2 and PGE(2) in the regulation of rhabdomyosarcoma cellular invasiveness and MMP-2 activity.

Anti-Inflammatory Agents, Non-Steroidal↗