The phenotypic relevance of allelic variation in the structure of the beta 2-adrenergic receptor (beta 2AR) expressed in lung cells is unknown. In particular, altered responsiveness of the beta 2AR expressed on airway smooth muscle, which are responsible for bronchodilation in the treatment of asthma, may be an important factor in the ultimate physiologic response to agonist. To approach this, we established primary cultures of human airway smooth muscle cells obtained at autopsy and developed a method to determine the beta 2AR genotype at the polymorphic loci of codons 16 and 27, using allele-specific polymerase chain reactions. Radioligand binding studies revealed that these cells expressed approximately 70 fmol/mg of receptor which was exclusively of the beta 2AR subtype. All cell lines obtained (n = 10) exhibited normal agonist binding and receptor-mediated activation of the adenylyl cyclase second messenger pathway. However, distinct differences were found in the response to long-term agonist exposure between the different beta 2AR genotypes. Cells expressing Arg at codon 16 (Arg16) traditionally referred to as wild-type, underwent 77.8 +/- 8.1% downregulations of beta 2AR following prolonged (24-h) exposure to the beta 2AR agonist isoproterenol (10 microM). In contrast, cells expressing Gly16 beta 2AR underwent enhanced agonist-promoted downregulation (95.6 +/- 1.7%, P < 0.05 versus Arg16), whereas cells expressing Glu27 beta 2AR were relatively resistant to such downregulation (29.5 +/- 12.7%, P < 0.01 versus Arg16). For cells expressing Glu27 beta 2AR, this difference resulted in a significant attenuation of agonist-promoted functional desensitization (33 +/- 7 versus 90 +/- 5% desensitization for Arg16, P < 0.001) following preincubation with 1 microM isoproterenol.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphoepithelial cyst (LEC) of the pancreas is a rare lesion of undetermined pathogenesis that had been documented almost exclusively in males. The literature on this entity is limited to reports of single or small numbers of cases. Here is presented a clinicopathologic analysis of 12 patients with LEC, 4 of whom were female. The mean age of the patients was 56 years. Four patients presented with abdominal pain and nausea, but in two patients, the cysts were detected incidentally. Only one patient had a history of chronic pancreatitis, and another had a family member with pancreatic cancer. In one patient, a clinical diagnosis of pseudocyst was rendered, and the remaining patients were clinically thought to have cystic neoplasms. None of the patients had any identifiable immunosuppression, HIV positivity, autoimmune disorder (such as Sjogren syndrome) or lymphoma. Seven cysts were located in the head of the pancreas, and 5 were in the tail. The mean size was 4.8 cm (range, 1.2-17 cm). Five LECs were multilocular, three were unilocular; in others, the number of loculi was not recorded. All were "macrocystic" lesions. Two patients had two separate lesions, both in the tail of the pancreas. Histologically, all cases were characterized by cysts, some containing keratin, and lined by mature stratified squamous epithelium surrounded by dense lymphoid tissue, often with prominent follicles. In some areas, the lining epithelium had more cuboidal, flattened, or transitional appearance. Mucinous goblet-like cells were seen in one case. Acute inflammation was not seen. Cystic lesions of the pancreas are relatively rare (1-3), but they constitute an important category with a challenging differential diagnosis at the clinical, radiological, and pathologic levels. In the past decade, wider application of radiographic techniques, coupled with the improvement in the surgical approach to this organ, has brought new attention to the cystic processes in the pancreas. As more cases of pancreatic cysts are being diagnosed and operated on, new clinicopathologic entities are being recognized (4 -6), and the old ones are becoming better characterized (7-10). Pseudocysts are the most common cystic lesions of the pancreas and usually occur as a complication of pancreatitis (11). True cysts, on the other hand, are most often neoplastic (1). The classification and understanding of these neoplastic pancreatic cysts have progressively improved in the last three decades. The serous and mucinous cystic neoplasms (SCN and MCN) described by Compagno and Oer-

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Complete removal of the esophageal epithelium without injury to the submucosa or muscularis propria is possible using this balloon-based RF electrode at 10 J/cm2 (2x) or 12 J/cm2 (1x or 2x). A second application (2x) does not significantly increase ablation depth. These data have been used to select the appropriate settings for treating intestinal metaplasia in trials currently under way.

Colonic bacteria have been implicated in the development of colon cancer. We have previously demonstrated that toll-like receptor 4 (TLR4), the receptor for bacterial lipopolysaccharide (LPS), is over-expressed in humans with colitis-associated cancer. Genetic epidemiologic data support a role for TLR4 in sporadic colorectal cancer (CRC) as well, with over-expression favoring more aggressive disease. The goal of our study was to determine whether TLR4 played a role as a tumor promoter in sporadic colon cancer. Using immunofluorescence directed to TLR4, we found that a third of sporadic human colorectal cancers over-express this marker. To mechanistically investigate this observation, we used a mouse model that over-expresses TLR4 in the intestinal epithelium (villin-TLR4 mice). We found that these transgenic mice had increased epithelial proliferation as measured by BrdU labeling, longer colonic crypts and an expansion of Lgr5+ crypt cells at baseline. In addition, villin-TLR4 mice developed spontaneous duodenal dysplasia with age, a feature that is not seen in any wild-type (WT) mice. To model human sporadic CRC, we administered the genotoxic agent azoxymethane (AOM) to villin-TLR4 and WT mice. We found that villin-TLR4 mice showed an increased number of colonic tumors compared to WT mice as well as increased β-catenin activation in non-dysplastic areas. Biochemical studies in colonic epithelial cell lines revealed that TLR4 activates β-catenin in a PI3K-dependent manner, increasing phosphorylation of β-cateninSer552, a phenomenon associated with activation of the canonical Wnt pathway. Our results suggest that TLR4 can trigger a neoplastic program through activation of the Wnt/β-catenin pathway. Our studies highlight a previously unexplored link between innate immune signaling and activation of oncogenic pathways, which may be targeted to prevent or treat CRC.

Histopathologic assessment is considered essential for the differentiation of recurrent hepatitis C (RHC) from acute cellular rejection (ACR) after liver transplantation (LT); however, there is limited information regarding its reliability. The aim of this study was to determine the interobserver and intraobserver agreement of the histopathologic diagnosis of RHC vs. ACR, and to determine the reliability of specific histopathologic features for the differentiation of RHC from ACR. Liver biopsy specimens from 105 consecutive patients transplanted for hepatitis C virus (HCV)-related liver disease were studied retrospectively. All the biopsies were performed for evaluation of abnormal liver enzymes within the 1st year after LT. The slides were blindly coded and assessed by 5 liver-transplant pathologists, practicing at 3 medical centers. The pathologists were asked to render a diagnosis, and determine the severity of the disease. Four of the pathologists were asked to determine the presence and severity of 36 histopathologic features. A total of 34 of the samples were then blindly resubmitted to each of the 4 pathologists to determine the intraobserver agreement. There was a slight agreement ( ‫؍‬ .12) among the 5 pathologists on the histopathologic diagnosis. All 5 pathologists were in agreement on the diagnosis of RHC in only 5 patients (5%) and on the diagnosis of ACR in only 2 patients (2%). The best agreement among any 4 pathologists was fair ( ‫؍‬ .20). Slight to moderate agreement occurred on the main histological features considered to be important in the diagnosis of ACR. Intraobserver agreement ranged from slight ( ‫؍‬ .19) to moderate ( ‫؍‬ .42) among 4 pathologists. In conclusion, the histopathologic differentiation of RHC from ACR after LT had relatively low interobserver and intraobserver agreement rates, and hence showed low reliability. Histopathologic assessment should be used cautiously for the differentiation of RHC from ACR post-LT. (Liver

Thyroid transcription factor-1 (TTF-1), a member of the NKx2 family of homeodomain transcription factors, is expressed in epithelial cells of the thyroid gland and the lung. To produce monoclonal antibodies specific for TTF-1, the polypeptide was expressed in E. coli and purified utilizing affinity chromatography of a polyhistidine-tagged TTF-1 fusion protein. Splenocytes from BALB/c mice immunized with recombinant TTF-1 were fused with P3x/63Ag8.653 myeloma cells to produce hybridomas. Tissue culture supernatant was screened for anti TTF-1 activity by ELISA employing recombinant TTF-1 as antigen. Hybridomas producing high-affinity antibodies were subcloned by limiting dilution. Antibodies from tissue culture fluid from an IgG1 clone (8G7G3/1) that stained the nuclei of paraffin-embedded human thyroid tissues were precipitation-purified and further characterized. The antibody stained a single 40-kDa polypeptide in immunoblots of nuclear extracts or lysates of cell lines known to express TTF-1 mRNA. MAb 8G7G3/1 also stained nuclei of tissue in a highly specific manner consistent with the pattern of expression obtained with an established polyclonal TTF-1 antibody and by in situ hybridization. MAb 8G7G3/1 was used for TTF-1 immunohistochemistry of human adenocarcinomas of the lung, colon, and breast as well as small cell carcinomas of the lung. TTF-1 was detected in primary lung adenocarcinomas and small cell carcinomas and was absent in colon and breast carcinomas. These findings demonstrate that anti-TTF-1 MAb 8G7G3/1 specifically binds TTF-1 in cell extracts and tissues and can be used to distinguish between lung and nonlung origin of a tumor.

Combination pegylated interferon with ribavirin appears to effective therapy in HCV recurrence and in HCV nonresponsive to interferon and ribavirin. This data reveals the difficulty and caution that must be taken when treating HCV-R liver-transplant recipients with combination pegylated alpha-2b interferon and ribavirin therapy.