Ex Vivo Experiment of Saline-Enhanced Hepatic Bipolar Radiofrequency Ablation with a Perfused Needle Electrode: Comparison with Conventional Monopolar and Simultaneous Monopolar Modes

The purpose of this study was to validate the saline-enhanced bipolar radiofrequency ablation (RFA) technique using a perfused electrode to increase RF-created coagulation necrosis, to compare that technique with monopolar RFAs and to find appropriate concentrations and volumes of perfused NaCl solution for the bipolar RFA. A total of 90 ablations were performed in explanted bovine livers. In the initial experiments to determine appropriate conditions for bipolar RFA, we created five thermal ablation zones in each condition, with instillations of varied concentrations (0.9–36%) or injection rates (30 mL/hr–120 mL/hr) of NaCl solution. After placement of one or two 16-gauge open-perfused electrodes into bovine livers, the NaCl solution was instilled into the tissue through the electrode. In the second part of the study, 10 ablation zones were created using one or two perfused electrodes for each of five groups under different conditions: a conventional monopolar mode with 0.9% NaCl solution (group A) or with 6% NaCl solution (group B), a simultaneous monopolar mode with 6% NaCl solution (group C) and a bipolar mode with 6% NaCl solution (groups D and E). RF was applied to each electrode for 20 min in groups A, B, C, and E, or for 10 min in group D. During RFA, we measured the tissue temperature 15 mm from the electrode. The temperature changes during the RFA and the dimensions of the ablation zones were compared among the groups. Bipolar RFA created larger short-axis diameters of coagulation necrosis with 6% NaCl solution (35.8 ± 15 mm) than with 0.9% NaCl solution (17 ± 9.7 mm) (P < 0.05). However, concentrations of NaCl solution above 6% did not further increase the extent of coagulation necrosis. In addition, bipolar RFA with 6% NaCl solution instillation at a rate of 1.0 mL/min (37.9 ± 5.4 mm) or 2.0 mL/min (35.6 ± 9.3 mm) produced larger diameters at the mid-point between the electrodes of the ablated lesion than did 0.5 mL/min (25.8 ± 9.3 mm) (P < 0.05). The bipolar mode showed a more rapid increase in temperature at the mid-point between the two probes, up to 60°C, than did the monopolar modes (P < 0.05). In addition, the bipolar RFA (group E) treated for 20 min showed a larger value of the short-axis diameter than did the conventional or simultaneous monopolar modes (P < 0.05), and bipolar RFA (group D) treated for 10 min, showed similar results with conventional monopolar modes treated for 20 min (P > 0.05): 31.0 ± 5.4 mm (group A); 28.8 ± 3.8 mm (group B); 25.5 ± 6.4 mm (group C); 32.6 ± 4.2 mm (group D); 49.4 ± 5.0 mm (group E). Bipolar RFA with instillation of 6% NaCl solution through an open perfusion system demonstrates better efficacy in creating a larger ablation zone than does conventional or simultaneous monopolar modes at the various times examined. Therefore, hypertonic saline-enhanced bipolar RFA seems to be a promising approach for treating larger liver tumors.     

CD4+CD25+ regulatory lymphocytes induce regression of intestinal tumors in ApcMin/+ mice

Colorectal cancer in humans results from sequential genetic changes in intestinal epithelia commencing with inactivation of the APC tumor suppressor gene. Roles for host immunity in epithelial tumorigenesis are poorly understood. It has been previously shown that CD4+CD25+ lymphocytes inhibit colitis-associated epithelial tumors in Rag-deficient mice. Here we show that addition of CD4+CD25+ lymphocytes in ApcMin/+ mice reduces multiplicity of epithelial adenomas. Interleukin-10 was required in regulatory cells for therapeutic effect. Recipients of regulatory cells showed increased apoptosis and down-regulation of cyclooxygenase-2 within tumors coincident with tumor regression. These data suggest a role for regulatory lymphocytes in epithelial homeostasis in the ApcMin/+ mouse model of intestinal polyposis. Similarities with cancer of the breast, prostate, lung, and other sites raise the possibility of broader roles for regulatory lymphocytes in prevention and treatment of epithelial cancers in humans.     

Induction of preneoplastic lung lesions in guinea pigs by cigarette smoke inhalation and their exacerbation by high dietary levels of vitamins C and E

The development of effective chemopreventive agents against cigarette smoke-induced lung cancer could be greatly facilitated by the availability of suitable laboratory animal models. Here we report that male Hartley guinea pigs treated with cigarette smoke by inhalation twice a day for 28 days developed preneoplastic lung lesions, including bronchial hyperplasia, dysplasia and squamous metaplasia, analogous to those found in human smokers. The lesions were accompanied by increased expression of proliferating cell nuclear antigen and activation of the serine/threonine kinase Akt in the bronchial epithelium. In contrast, no lung lesions were found in guinea pigs ('sham smoked') that were submitted to identical procedures but without cigarettes. Compared with a diet low in vitamin C (50 p.p.m.) and vitamin E (15 p.p.m.), a diet high in vitamin C (4000 p.p.m.) and vitamin E (40 p.p.m.) significantly increased the incidence of these lesions. The inclusion of 1,4-phenylenebis(methylene)selenocyanate (p-XSC), a synthetic chemopreventive organoselenium compound, in the high vitamin C-high vitamin E diet at a level of 15 p.p.m. as selenium appeared to decrease the lesion incidence. Administration of (-)-epigallocatechin gallate, a powerful green tea polyphenolic antioxidant, at 560 p.p.m. in the drinking water had no effect. As in human smokers, levels of ascorbate in blood plasma, lung, liver and the adrenal glands were significantly decreased by cigarette smoke inhalation. These results identify a relevant in vivo laboratory model of cigarette smoke-induced lung cancer, suggest that p-XSC may have activity as a chemopreventive agent against cigarette smoke-induced lung lesions and provide additional evidence that very high dietary levels of certain antioxidants can have co-carcinogenic activity in cigarette smoke-induced lung cancer.     

Expression and prognostic significance of 14-3-3sigma and ERM family protein expression in periampullary neoplasms

Aberrant gene expression in pancreatic ductal adenocarcinomas contributes to the dismal outcome of patients who develop this disease. The 5' region of 14-3-3sigma (stratifin) is hypomethylated in pancreatic adenocarcinomas and is associated with gene overexpression. In multiple experimental systems, ezrin (ERM, Radixin, Moesin) has been identified as being important in the metastatic behavior of pancreatic and other cancers. We investigated the prognostic significance of aberrant expression of 14-3-3sigma and the ERM proteins (Ezrin, radixin, Moesin) in a series of invasive periampullary adenocarcinomas including 300 infiltrating pancreatic adenocarcinomas, 54 ampullary adenocarcinomas, and 33 noninvasive intraductal papillary mucinous neoplasms from patients who underwent pancreaticoduodenal resection at The Johns Hopkins Hospital, Baltimore, MD, between 1991 and 2003. Two-hundred fourty-four (82%) primary infiltrating adenocarcinomas of the pancreas demonstrated positive expression of the 14-3-3sigma, 45 (15%) showed weak immunolabelling, and 9 (3%) were negative. 201 (68%) showed positive immunolabeling of the ERM proteins, 75 (25%) demonstrated weak expression and 20 (7%) no expression. A similar proportion of ampullary cancers showed 14-3-3sigma and ERM protein expression. Expression of 14-3-3sigma and ERM protein was more likely in poorly differentiated cancers (p = 0.00005), and their expression was associated with poor survival in univariate analysis (p = 0.09). By multivariate analysis, patients whose cancers expressed 14-3-3sigma, but not ERM tended to have a poorer prognosis (Hazard ratio, 1.4; 0.9-2.2, p = 0.14). Aberrant expression of 14-3-3sigma may contribute to the outcome of patients with pancreatic ductal adenocarcinoma.     

Changes of smoking behavior and serum adrenocorticotropic hormone, cortisol, prolactin, and endogenous opioids levels in nicotine dependence after naltrexone treatment

This study was done to evaluate the therapeutic effects of naltrexone on smoking behaviors and to measure the changing of brain substances for elucidating the mode of action by naltrexone. Twenty-five voluntarily participated healthy male smokers were randomly assigned to naltrexone group or placebo group for 2 weeks. In this study, naltrexone group showed significant reduction in daily cigarette consumption amount, the expiratory CO levels, brief questionnaire for smoking urge (B-QSU) score, and FTQ score. However, only 2 subjects in naltrexone group quitted smoking completely at 4th week. Plasma levels of pituitary hormones (ACTH, cortisol, and prolactin) and endogenous opioids (beta-endorphin and dynorphin A) were checked weekly before and after the 'provocation and smoking coupled' stimulus once in a week for 3 weeks. In naltrexone group, pituitary hormones showed upward tendencies even though only the prolactin had statistical significance. However, beta-endorphin and dynorphin A were not significantly different between the two groups. It was suggested that naltrexone made effects on hypothalamo-pituitary-adrenocortical axis activity as well as smoking behavior. However, the meaning of these endocrinal changes by naltrexone is not conclusive, whether it is beneficial or aversive.     

Depletion of intracellular zinc and copper with TPEN results in apoptosis of cultured human retinal pigment epithelial cells

PURPOSE: Although zinc deficiency may contribute to the pathogenesis of age-related macular degeneration, how it leads to retinal pigment epithelium (RPE) degeneration is unknown. To investigate this, cultured human RPE cells were rendered zinc depleted with a membrane-permeant metal chelator, N,N,N',N-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN), and the resultant cytopathic changes were examined. METHODS: RPE cell degeneration was examined with light microscopy, TdT-mediated dUTP nick end labeling (TUNEL) staining, Hoechst dye staining, and electron microscopy and quantified with cell counting or lactate dehydrogenase release assay. The effect of sublethal zinc depletion on the vulnerability of RPE cells to UV irradiation or hydrogen peroxide (H(2)O(2)) exposure, was studied in cultures without or with pretreatment with low-concentration TPEN. RESULTS: Exposure to 1 to 4 microM TPEN for 48 hours induced RPE cell death in a concentration-dependent manner. Features of apoptosis such as membrane blebbing, chromatin condensation, nuclear fragmentation, and caspase-3 activation, accompanied the TPEN-induced cell death. Addition of equimolar zinc or copper completely reversed TPEN-induced apoptosis, whereas addition of iron had no effect. As in apoptosis of several other cell types including neurons, a protein synthesis inhibitor as well as caspase inhibitors blocked TPEN-induced apoptosis. On the contrary, at sublethal concentrations, TPEN increased the vulnerability of RPE cells to subsequent UV irradiation but not to H(2)O(2) exposure. CONCLUSIONS: The present results suggest that depletion of intracellular zinc and copper, but not copper alone, may be harmful to RPE cells, directly inducing apoptosis or indirectly increasing vulnerability of RPE cells to UV injury. The present culture model may be useful for gaining insights into the mechanisms of zinc depletion-associated RPE cell degeneration.     

Effect of hepatic cirrhosis on the pharmacokinetics of theophylline in rats

The experimental hepatic cirrhosis was induced either by bile duct ligation (BDL) or by pretreatment with dimethylnitrosamine (DMNA). The pharmacokinetics of theophylline were studied after a single intravenous or a single oral administration. Using the ultrafiltration method, protein-drug binding experiments were also carried out. The bilirubin level was several-fold increased by BDL, but not by DMNA treatment. The albumin content was decreased in both cirrhotic groups. The total clearance (Clt, ml/kg/hr) of theophylline in both hepatic cirrhosis groups significantly decreased and the terminal half-life (t_1/2) in the cirrhotic rats was increased about two-fold after intravenous and oral administration. The volume of distribution at steady state (Vdss, ml/kg) was increased slightly in the cirrhotic groups. Protein binding in BDL (8.67±4.85%) decreased about four-folds, but in DMNA (73.00±9.85%) similar result, was observed as compared with the control. Increased free fraction of theophylline did not increase the volume of distribution in BDL. Therefore decreased total body clearance of theophylline was mainly due to decreased intrinsic clearance of theophylline in the liver. The absolute bioavailability of theophylline in these experiments was between 63.8 and 72.8%(66.1% in BDL, 63.8% in Sham operated and Control, 72.8% in DMNA). These results suggest that in the experimental hepatic cirrhosis model, administration route does not affect the disposition of theophylline.