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IMPORTANCE Significant controversy exists regarding routine intraoperative cholangiography in preventing common duct injury during cholecystectomy. OBJECTIVE To investigate the association between intraoperative cholangiography use during cholecystectomy and common duct injury. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study of all Texas Medicare claims data from 2000 through 2009. We identified Medicare beneficiaries 66 years or older who underwent inpatient or outpatient cholecystectomy for biliary colic or biliary dyskinesia, acute cholecystitis, or chronic cholecystitis. We compared results from multilevel logistic regression models to the instrumental variable analyses. INTERVENTIONS Intraoperative cholangiography use during cholecystectomy was determined at the level of the patients (yes/no), hospitals (percentage intraoperative cholangiography use for all cholecystectomies at the hospital), and surgeons (percentage use for all cholecystectomies performed by the surgeon). Percentage of use at the hospital and percentage of use by surgeon were the instrumental variables. MAIN OUTCOMES AND MEASURES Patients with claims for common duct repair operations within 1 year of cholecystectomy were considered as having major common duct injury. RESULTS Of 92 932 patients undergoing cholecystectomy, 37 533 (40.4%) underwent concurrent intraoperative cholangiography and 280 (0.30%) had a common duct injury. The common duct injury rate was 0.21% among patients with intraoperative cholangiography and 0.36% among patients without it. In a logistic regression model controlling for patient, surgeon, and hospital characteristics, the odds of common duct injury for cholecystectomies performed without intraoperative cholangiography were increased compared with those performed with it (OR, 1.79 [95% CI, 1.35-2.36]; P < .001). When confounding was controlled with instrumental variable analysis, the association between cholecystectomy performed without intraoperative cholangiography and duct injury was no longer significant (OR, 1.26 [95% CI. 0.81-1.96]; P = .31). CONCLUSIONS AND RELEVANCE When confounders were controlled with instrumental variable analysis, there was no statistically significant association between intraoperative cholangiography and common duct injury. Intraoperative cholangiography is not effective as a preventive strategy against common duct injury during cholecystectomy. [ABSTRACT FROM AUTHOR]

The mammalian target of rapamycin (mTOR) signaling exists in two complexes: mTORC1 and mTORC2. Neurotensin (NT), an intestinal hormone secreted by enteroendocrine (N) cells in the small bowel, has important physiological effects in the gastrointestinal tract. The human endocrine cell line BON abundantly expresses the NT gene and synthesizes and secretes NT in a manner analogous to that of N cells. Here, we demonstrate that the inhibition of mTORC1 by rapamycin (mTORC1 inhibitor), torin1 (both mTORC1 and mTORC2 inhibitor) or short hairpin RNA-mediated knockdown of mTOR, regulatory associated protein of mTOR (RAPTOR), and p70 S6 kinase (p70S6K) increased basal NT release via upregulating NT gene expression in BON cells. c-Jun activity was increased by rapamycin or torin1 or p70S6K knockdown. c-Jun overexpression dramatically increased NT promoter activity, which was blocked by PD98059, an mitogen-activated protein kinase kinase (MEK) inhibitor. Furthermore, overexpression of MEK1 or extracellular signal-regulated kinase 1 (ERK1) increased c-Jun expression and NT promoter activity. More importantly, PD98059 blocked rapamycin- or torin1-enhanced NT secretion. Consistently, rapamycin and torin1 also increased NT gene expression in Hep3B cells, a human hepatoma cell line that, similar to BON, expresses high levels of NT. Phosphorylation of c-Jun and ERK1/2 was also increased by rapamycin and torin1 in Hep3B cells. Finally, we showed activation of mTOR in BON cells treated with amino acids, high glucose, or serum and, concurrently, the attenuation of ERK1/2 and c-Jun phosphorylation and NT secretion. Together, mTORC1, as a nutrient sensor, negatively regulates NT secretion via the MEK/ERK/c-Jun signaling pathway. Our results identify a physiological link between mTORC1 and MEK/ERK signaling in controlling intestinal hormone gene expression and secretion. [ABSTRACT FROM AUTHOR]

The article presents a study which determines whether racial disparities relative to surgical resection use for locoregional pancreatic cancer occur during or after surgical evaluation. The study used logistic regression to identify the impact of race and univariate models to compare black and white pancreatic cancer patients. The result indicates that higher rates of surgical evaluation in black patients could become the first step to remove the disparity in the resection rate.

Transforming growth factor (TGF)-β-dependent apoptosis is important in the elimination of damaged or abnormal cells from normal tissues in vivo. Previously, we have shown that TGF-β inhibits the growth of rat intestinal epithelial (RIE)-1 cells. However, RIE-1 cells are relatively resistant to TGF-β-induced apoptosis due to a low endogenous Smad3-to-Akt ratio. Overexpression of Smad3 sensitizes RIE-1 cells (RIE-1/Smad3) to TGF-β-induced apoptosis by altering the Smad3-to-Akt ratio in favor of apoptosis. In this study, we utilized a genomic approach to identify potential downstream target genes that are regulated by TGF-β/Smad3. Total RNA samples were analyzed using Affymetrix oligo- nucleotide microarrays. We found that TGF-β regulated 518 probe sets corresponding to its target genes. Interestingly, among the known apoptotic genes included in the microarray analyses, only caspase-3 was induced, which was confirmed by real-time RT-PCR. Further- more, TGF-β activated caspase-3 through protein cleavage. Upstream of caspase-3, TGF-β induced mitochondrial depolarization, cytochrome c release, and cleavage of caspase-9, which suggests that the intrinsic apoptotic pathway mediates TGF-β-induced apoptosis in RIE-1/Smad3 cells. [ABSTRACT FROM AUTHOR]

Transforming growth factor-betas (TGF-βs), cytokines expressed in the colon, play important roles as tumor suppressors and tumor promoters during colorectal carcinogenesis. TGF-β signaling pathway involves activation of Smad2 and Smad3 by the type I receptor and formation of Smad2/3/4 heteromeric complexes that enter the nucleus to regulate transcription. Most human colorectal cancers are resistant to the tumor suppressor effects of TGF-β, and a subset of human colorectal cancers have mutations in Smad2 and Smad4. The purpose of this study was to determine whether Smads are required for TGF-β signaling in colon cancer cells. First, we selected a colon cancer cell line (MC-26) that has a functional TGF-β signaling pathway. We found that MC-26 cells expressed Smad2, Smad3, and Smad4 mRNAs by reverse transcription-polymerase chain reaction and confirmed that the TGF-β signaling pathway is functional using a transient transfection assay with 3TP-Lux reporter plasmid. TGF-β also inhibited cell growth and induced apoptosis in MC-26 cells. When MC-26 cells were transiently transfected with dominant-negative carboxyl-terminal truncation mutants of Smad2, Smad3, and Smad4, TGF-β-induced 3TP-Lux reporter activity was significantly reduced, suggesting that Smad2, Smad3, and Smad4 are attractive novel therapeutic targets fur regulating TGF-β signaling in colorectal cancers. Because MC-26 cells express TGF-β activated Smads, have a functional TGF-β signaling pathway, and are sensitive to the growth inhibitory and apoptotic effects of TGF-β, they can serve as an excellent model to examine TGF-β signaling in colorectal cancers. [ABSTRACT FROM AUTHOR]

Mitochondria, organelles essential for ATP production, play a central role in a number of cellular functions, including the regulation of insulin secretion. Neurotensin (NT), an important regulatory intestinal hormone, has been implicated in fatty acid translocation, gut motility and secretion, and intestinal cell growth; however, mechanisms regulating NT secretion have not been entirely defined. The purpose of this study was to determine the effect of inhibition of mitochondrial gene transcription on NT secretion. BON cells, a novel human carcinoid cell line that produces and secretes NT peptide and expresses the gene encoding NT (designated NT/N), were treated with ethidium bromide (EB; 0.05, 0.1, and 0.4 µg/ml), an inhibitor of DNA and RNA synthesis, or vehicle over a time course (1-4 days). Cells were then stimulated with either ACh (100 µM) or phorbol 12 myristate, 13-acetate (PMA, 10 nM) for 30 min. Media and cells were extracted, and NT peptide measured by RIA. Treatment with EB had no effect on BON cell viability or cell cycle distribution over the 4-day course. In contrast, EB treatment produced a dose-dependent reduction of mitochondrial gene expression; however, NT/N gene expression was not altered. Mitochondrial inhibition by EB treatment suppressed NT secretion induced by ACh and PMA, both in a dose-dependent manner. EB-mediated inhibition of NT secretion and mitochondrial gene expression was reversed with removal of EB. Our results demonstrate that inhibition of mitochondrial gene transcription suppresses both ACh- and PMA-stimulated NT release. These findings are the first to demonstrate that mitochondrial function is important for agonist-mediated NT secretion. [ABSTRACT FROM AUTHOR]

Transforming growth factor ß (TGF-ß) induces both apoptosis and cell-cycle arrest in some cell lines, but only growth arrest in others. It is not clear how this differential response to TGF-ß is specified. Smad proteins are critical mediators of TGF-ß signalling. After stimulation by TGF-ß, Smad2 and Smad3 become phosphorylated by the activated TGF-ß receptor kinases, oligomerize with Smad4, translocate to the nucleus and regulate the expression of TGF-ß target genes. Here we report that the sensitivity to TGF-ß-induced apoptosis is regulated by crosstalk between the Akt/PKB serine/threonine kinase and Smad3 through a mechanism that is independent of Akt kinase activity. Akt interacts directly with unphosphorylated Smad3 to sequester it outside the nucleus, preventing its phosphorylation and nuclear translocation. This results in inhibition of Smad3-mediated transcription and apoptosis. Furthermore, the ratio of Smad3 to Akt correlates with the sensitivity of cells to TGF-ß-induced apoptosis. Alteration of this ratio changes the apoptotic, but not the growth-inhibitory, responses of cells to TGF-ß. These findings identify an important determinant of sensitivity to TGF-ß-induced apoptosis that involves crosstalk between the TGF-ß and phosphatidylinositol-3-OH kinase (PI(3)K) pathways. [ABSTRACT FROM AUTHOR]

Neurotensin (NT) plays an important role in gastrointestinal secretion, motility, and growth. The mechanisms regulating NT secretion are not entirely known. Our purpose was to define the role of the PKC signaling pathway in secretion of NT from BON cells, a human pancreatic carcinoid cell line that produces and secretes NT peptide. We demonstrated expression of all 11 PKC isoforms at varying levels in untreated BON cells. Expression of PKC-α, -β2, -δ, and -μ isoforms was most pronounced. Immunofluorescent staining showed PKC-α and -μ expression throughout the cytoplasm and in the membrane. Also, significant fluorescence of PKC-δ was noted in the nucleus and cytoplasm. Treatment with PMA induced translocation of PKC-α -δ, and -μ from cytosol to membrane. Activation of PKC-α, -δ, and -μ was further confirmed by kinase assays. Addition of PKC-α inhibitor Gö-6976 at a nanomolar concentration, other PKC inhibitors Gö-6983 and GF-109203X, or PKC-δ-specific inhibitor rottlerin significantly inhibited PMA-mediated NT release. Overexpression of either PKC-α or -δ increased PMA-mediated NT secretion compared with control cells. We demonstrated that PMA-mediated NT se- cretion in BON cells is associated with translocation and activation of PKC-α, -δ, and -μ. Furthermore, inhibition of PKC-α and -δ blocked PMA-stimulated NT secretion, suggesting a critical role for these isoforms in NT release. [ABSTRACT FROM AUTHOR]

Examines the contribution of DNA methylation to expression of the human neurotensin/neuromedin N (NT/N) gene. Expression of NT/N in fetal liver and adult small bowel; Absence of positive transcription factors in the expression; Characteristics of neurotensin; Cloning of the full-length human NT/N.