Faculty Bibliography

Recent studies suggest accurate prediction of tissue of origin for human cancers can be achieved by applying sophisticated statistical learning procedures to gene expression data obtained from DNA microarrays. We have pursued the hypothesis that a more straightforward and equally accurate strategy for classifying human tumors is to use a simple algorithm that considers gene expression levels within a tree-based framework that encodes limited information about pathology and tissue ontogeny. By considering gene expression data within this framework, we found only a small number of genes were required to achieve a relatively high accuracy level in tumor classification. Using as few as 45 genes we were able to classify 157 of 190 human malignant tumors correctly, which is comparable to previous results obtained with sophisticated classifiers using thousands of genes. Our simple classifier accurately predicted the origin of metastatic tumors even when the classifier was trained using only primary tumors, and the classifier produced accurate predictions when trained and tested on expression data from different labs, and from different microarray platforms. Our findings suggest that accurate and robust cancer diagnosis from gene expression profiles can be achieved by mimicking the classification strategies routinely used by surgical pathologists.

To clarify the lineage relationship between cells that express the neural stem cell marker nestin and endocrine cells of the pancreas, we analyzed offspring of a cross between mice carrying a nestin promoter/enhancer-driven cre-recombinase (Nestin-cre) and C57BL/6J-Gtrosa26(tm1Sor) mice that carry a loxP-disrupted beta-galactosidase gene (Rosa26). In nestin-cre(+/tg);R26R(loxP/+) embryos, cre-recombinase was detected in association with nestin-positive cells in the pancreatic mesenchyme with some of the nestin-positive cells lining vascular channels. In postnatal mice, pancreatic beta-galactosidase expression was restricted to vascular endothelial cells of the islet and a subset of cells in the muscularis of arteries in a distribution identical to endogenous nestin expression. Ex vivo explants of mouse pancreatic ducts grew dense cultures that costained for nestin and beta-galactosidase, demonstrating recombination in vitro. The cultures could be differentiated into complex stereotypic structures that contain nestin- and insulin-expressing cells. Nestin-cre(+/tg);R26R(loxP/+)-derived duct cultures showed that insulin-positive cells were negative for beta-galactosidase. These results indicate that both in vivo and in vitro pancreatic endocrine cells arise independently of nestin-positive precursors. The apparent vascular nature of the nestin-positive cell population and the close association with endocrine cells suggest that nestin-positive cells play an important role in the growth and maintenance of the islet.

The molecular basis of pancreatic cancer is not understood. Previous attempts to determine the specific genes expressed in pancreatic cancer have been hampered by similarities between adenocarcinoma and chronic pancreatitis. In the current study, microarrays (Affymetrix) were used to profile gene expression in pancreatic adenocarcinoma (10), pancreatic cancer cell lines (7), chronic pancreatitis (5), and normal pancreas (5). Molecular profiling indicated a large number of genes differentially expressed between pancreatic cancer and normal pancreas but many fewer differences between pancreatic cancer and chronic pancreatitis, likely because of the shared stromal influences in the two diseases. To specifically identify genes expressed in neoplastic epithelium, we selected genes more highly expressed (>2-fold, p < 0.01) in adenocarcinoma compared with both normal pancreas and chronic pancreatitis and which were also highly expressed in pancreatic cancer cell lines. This strategy yielded 158 genes, of which 124 were not previously associated with pancreatic cancer. Quantitative-reverse transcription-PCR for two molecules, S100P and 14-3-3sigma, validated the microarray data. Support for the success of the neoplastic cell gene expression identification strategy was obtained by immunocytochemical localization of four representative genes, 14-3-3sigma, S100P, S100A6, and beta4 integrin, to neoplastic cells in pancreatic tumors. Thus, comparisons between pancreatic adenocarcinoma, pancreatic cancer cell lines, normal pancreas, and chronic pancreatitis have identified genes that are selectively expressed in the neoplastic epithelium of pancreatic adenocarcinoma. These data provide new insights into the molecular pathology of pancreatic cancer that may be useful for detection, diagnosis, and treatment.

Pancreatic secretion can be influenced by cholecystokinin (CCK) either directly via actions on acinar cells or indirectly via actions on nerves. The presence and functional roles of CCK receptors on human pancreatic acinar cells remains unclear. In the current study human pancreatic acini were isolated and then treated with CCK-8, gastrin and/or carbachol. Functional parameters were measured including intracellular [Ca2+] and amylase secretion. It was observed that human acini did not respond to CCK agonists but did respond to carbachol with robust increases in functional parameters. Adenoviral-mediated gene transfer of CCK1 or CCK2 receptors to the human cells resulted in cell responses to CCK agonists. In order to determine the reason for the lack of responsiveness of the human acini, expression of receptor mRNAs was determined using quantitative RT-PCR and localized by in situ hybridization. mRNA levels for CCK1 receptors were approximately 30 times lower than those of CCK2 receptors, which were approximately 10 times lower than those of m3 Ach receptors as measured by quantitative PCR. Neither CCK1 nor CCK2 receptors were localized in adult human pancreas by in situ hybridization. These results indicate that human pancreatic acinar cells do not respond directly to CCK receptor activation and this is likely due to an insufficient level of receptor expression.

OBJECTIVE: To familiarize surgeons with the specific complications of cutaneous, gastrointestinal, inhalation, and systemic infection with Bacillus Anthracis, which may require surgical treatment. SUMMARY BACKGROUND DATA: The recent cases of intentional exposure to Bacillus Anthracis in the United States make familiarity with the basic microbiology, clinical manifestations, diagnosis, treatment, and control of this disease essential if mortality and morbidity is to be minimized, particularly following mass exposure. Although the treatment of Bacillus Anthracis infection is primarily medical, there are specific surgical complications with which the surgeon should be familiar. METHODS: A review of the literature was undertaken, utilizing electronic databases on infection with Bacillus Anthracis, as well as consultation with experts in this field. Emphasis was placed on the diagnosis and treatment of complications of infection that might require surgical intervention. RESULTS: Cutaneous anthrax infection results in eschar formation and massive soft tissue edema. When involving the extremities, increased compartment pressure requiring fasciotomy may result. Primary infection of the gastrointestinal tract may result in oropharyngeal edema and respiratory compromise requiring a surgical airway. Direct involvement of the lower gastrointestinal tract can result in intestinal ulceration, necrosis, bleeding, and perforation, which would require surgical exploration and resection of affected segments. Systemic sepsis, most often associated with inhalation anthrax, can cause massive ascites, electrolyte derangements, and profound shock requiring aggressive fluid resuscitation and careful hemodynamic monitoring and respiratory support. Systemic anthrax infection can also lead to gastrointestinal involvement by hematogenous dissemination, resulting in complications and requiring surgical management similar to direct gastrointestinal infection. CONCLUSIONS: Cutaneous, gastrointestinal, inhalation and systemic infection with Bacillus Anthracis can result in complications which would require familiarity with the pathogenesis and manifestations of this disease in order to recognize and treat promptly and successfully by surgical intervention.

BACKGROUND & AIMS/OBJECTIVE:The role of nuclear factor kappaB (NF-kappaB) activation in acute pancreatitis is uncertain. The transcription factor NF-kappaB is activated early in acute pancreatitis, and NF-kappaB is widely considered a key element in inflammatory responses based on its ability to regulate the expression of inflammatory mediators in vitro. However, its role in vivo in specific diseases remains unclear, and the current data on the role of NF-kappaB in acute pancreatitis is primarily correlative. METHODS:In this study, NF-kappaB was directly activated within the pancreas using adenoviral-mediated transfer of an active subunit, RelA/p65 (Adp65), delivered by intraductal injection. RESULTS:Administration of Adp65 led to the infection of a population of acinar cells within the pancreas, the activation of NF-kappaB, the expression of NF-kappaB target genes, and an inflammatory response. Administration of Adp65 increased the infiltration of neutrophils to the pancreas and lung and caused widespread damage to pancreatic acinar cells. In contrast, at the same titer, control adenovirus (AdGFP) had no effect on these parameters. The level of NF-kappaB activation and the severity of inflammation were reduced when an adenovirus bearing the inhibitory subunit IkappaB-alpha was coadministered with Adp65. CONCLUSIONS:Thus, activation of NF-kappaB within the pancreas was sufficient for the initiation of an inflammatory response in this model. These results help define the specific role of NF-kappaB activation in acute pancreatitis.