Donald N. Reed

Redox-mediated enrichment of self-renewing adult human pancreatic cells that possess endocrine differentiation potential.

Objectives: The limited availability of transplantable human islets has stimulated the development of methods needed to isolate adult pancreatic stem/progenitor cells capable of self-renewal and endocrine differentiation. The objective of this study was to determine whether modulation of intracellular redox state with N-acetyl-l-cysteine (NAC) would allow for the propagation of pancreatic stem/progenitor cells from adult human pancreatic tissue. Methods: Cells were propagated from human pancreatic tissue using a serum-free, low-calcium medium supplemented with NAC and tested for their ability to differentiate when cultured under different growth conditions. Results: Human pancreatic cell (HPC) cultures coexpressed &agr;-amylase, albumin, vimentin, and nestin. The HPC cultures, however, did not express other genes associated with differentiated pancreatic exocrine, duct, or endocrine cells. A number of transcription factors involved in endocrine cell development including Beta 2, Islet-1, Nkx6.1, Pax4, and Pax6 were expressed at variable levels in HPC cultures. In contrast, pancreatic duodenal homeobox factor 1 (Pdx-1) expression was extremely low and at times undetectable. Overexpression of Pdx-1 in HPC cultures stimulated somatostatin, glucagon, and carbonic anhydrase expression but had no effect on insulin gene expression. HPC cultures could form 3-dimensional islet-like cell aggregates, and this was associated with expression of somatostatin and glucagon but not insulin. Cultivation of HPCs in a differentiation medium supplemented with nicotinamide, exendin-4, and/or LY294002, an inhibitor of phosphatidylinositol-3 kinase, stimulated expression of insulin mRNA and protein. Conclusion: These data support the use of intracellular redox modulation for the enrichment of pancreatic stem/progenitor cells capable of self-renewal and endocrine differentiation.

Cigarette smoke components inhibited intercellular communication and differentiation in human pancreatic ductal epithelial cells

Smoking is a well‐documented risk factor for the development of pancreatic adenocarcinoma. Although the most abundant polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke are methylated anthracenes and phenanthrenes, the epigenetic toxicity of these compounds has not been extensively studied. We previously showed that methylanthracenes, which possess a bay‐like structure, affect epigenetic events such as an induced release of arachidonic acid, inhibition of gap junctional intercellular communication (GJIC) and induction of mitogen‐activated protein kinases in a pluripotent rat liver epithelial stem cell line. Anthracenes with no bay‐like structures were inactive. These biological effects are all molecular events associated with the promotional phase of cancer. A human immortalized, nontumorigenic pancreatic ductal epithelial cell line, H6c7, was examined to study the epigenetic toxicity of PAHs related to pancreatic cancer by using scrape‐loading dye transfer, immunostaining, RT‐PCR and telomerase assay methods. H6c7 cells were GJIC‐incompetent and exhibited high telomerase activity when grown in growth factor and hormone‐supplemented medium. In the presence of the cAMP elevating drugs (forskolin and IBMX) the cells became GJIC competent and expressed connexins. Telomerase activity was also decreased by cAMP elevating drug treatment. After induction of cAMP, 1‐methylanthracene with bay‐like structures inhibited GJIC, whereas the 2‐methylanthracene lacking a bay‐like structure had no effect on GJIC. Telomerase activity remained high in 1‐methylanthracene treatment but not with 2‐methylanthracene. These results indicate that a prominent component of cigarette smoke, namely methylanthracenes with distinct structural configurations, could be a potential etiological agent contributing to the epigenetic events of pancreatic cancer.

INTERVENTIONAL ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY AND ENDOSCOPIC SURGERY

Interventional endoscopic techniques have been indespensible in almost every area of modern surgery. As surgeons, we need to continue to advance our skills in these areas if we expect to continue to be involved in these aspects of patient care.

Subcutaneous access ports with fenestrated catheters for improved management of recurrent pleural effusions

Repeated percutaneous thoracentesis can involve serious complications, such as pneumothorax or infection. Alternatives such as placement of chest tubes or pleurodesis have their own potential complications. Creative options such as pleuroperitoneal shunting and video thoracoscopy have previously been used to avoid the disadvantages of repeated percutaneous thoracentesis. This paper describes an easy and effective method for managing these patients without repeated percutaneous thoracentesis. A port is inserted that can be accessed percutaneously and immediately for needed aspirations. We have successfully performed this procedure on 6 patients. Our hope is that the easy access using a short needle into the port aperture will allow the thoracentesis to be performed by appropriately instructed and supervised paramedical personnel. Also, with fewer postprocedure chest radiographs or hemothoraceses, future benefits from this procedure could include cost effectiveness.