Delayed graft function (DGF) impacts short-and longterm outcomes. We present a model for predicting DGF after renal transplantation. A multivariable logistic regression analysis of 24 337 deceased donor renal transplant recipients (2003-2006) was performed. We developed a nomogram, depicting relative contribution of risk factors, and a novel web-based calculator (www.transplantcalculator.com/DGF) as an easily accessible tool for predicting DGF. Risk factors in the modern era were compared with their relative impact in an earlier era (1995)(1996)(1997)(1998). Although the impact of many risk factors remained similar over time, weight of immunological factors attenuated, while impact of donor renal function increased by 2-fold. This may reflect advances in immunosuppression and increased utilization of kidneys from expanded criteria donors (ECDs) in the modern era. The most significant factors associated with DGF were cold ischemia time, donor creatinine, body mass index, donation after cardiac death and donor age. In addition to predicting DGF, the model predicted graft failure. A 25-50% probability of DGF was associated with a 50% increased risk of graft failure relative to a DGF risk <25%, whereas a >50% DGF risk was associated with a 2-fold increased risk of graft failure. This tool is useful for predicting DGF and long-term outcomes at the time of transplant.

Cellular pools of free arachidonic acid are tightly controlled through enzymatic release of the fatty acid and subsequent utilization by downstream enzymes including the cyclooxygenases. Arachidonic acid cleavage from membrane phospholipids is accomplished by the actions of phospholipase A 2 (PLA 2 ). Upon release, free arachidonic acid provides substrate for the synthesis of eicosanoids. However, under certain conditions, arachidonic acid may participate in ceramidemediated apoptosis. Disruption of arachidonic acid homeostasis can shift the balance of cell turnover in favor of tumorigenesis, via overproduction of tumor-promoting eicosanoids or alternatively by limiting proapoptotic signals. In the following study, we evaluated the influence of genetic deletion of a key intracellular phospholipase, cytoplasmic PLA 2 (cPLA 2 ), on azoxymethane-induced colon tumorigenesis. Heterozygous and null mice, upon treatment with the organotropic colon carcinogen, azoxymethane, developed a significant (P < 0.05) increase in colon tumor multiplicity (7.2-fold and 5.5-fold, respectively) relative to their wild-type littermates. This enhanced tumor sensitivity may be explained, in part, by the attenuated levels of apoptosis observed by terminal deoxynucleotidyl transferase-mediated nick end labeling staining within the colonic epithelium of heterozygous and null mice (% % %50% of wild type). The lower frequency of apoptotic cells corresponded with reduced ceramide levels (69% and 46% of wild-type littermates, respectively). Remarkably, increased tumorigenesis resulting from cPLA 2 deletion occurred despite a significant reduction in prostaglandin E 2 production, even in cyclooxygenase-2-overexpressing tumors. These data contribute new information that supports a fundamental role of cPLA 2 in the control of arachidonic acid homeostasis and cell turnover. Our findings indicate that the proapoptotic role of cPLA 2 in the colon may supercede its contribution to eicosanoid production in tumor development.

AKR/J mice are resistant to the tumorigenic properties of the colon carcinogen, azoxymethane (AOM). Following AOM exposure, limited numbers of preneoplastic lesions, referred to as aberrant crypt foci (ACF), are formed in the colon, and their progression to tumors rarely occurs. To determine whether genetic resistance can be overcome by exposure to a dietary tumor promoter, AOM-exposed AKR/J mice were fed a diet containing 0.25% deoxycholic acid (DCA). DCA exposure was begun 1 wk prior to or 1 wk after tumor initiation with AOM. Mice placed on the DCA diet prior to AOM treatment developed a significantly higher multiplicity of ACF compared to AOM-exposed mice fed a control diet (15.50 +/- 0.96 vs. 6.17 +/- 0.48, respectively; P < 0.05). When DCA exposure was begun after AOM treatment (post-initiation), ACF formation was further enhanced (34.00 +/- 1.22). Interestingly, increased numbers of ACF were associated with the presence of nuclear beta-catenin, assessed by immunohistochemistry. While approximately 33% of ACF from mice exposed to DCA prior to AOM treatment contained positive nuclear beta-catenin staining, approximately 77% of ACF from mice fed DCA after AOM were positive. Accumulation of nuclear beta-catenin was not associated with a loss of E-cadherin from the plasma membrane, although loss of APC staining was a consistent feature of most AOM-induced ACF, regardless of DCA exposure. These results demonstrate that exposure to DCA, an important digestive component, is sufficient to sensitize the resistant AKR/J colon to formation of high-grade dysplasia, and that nuclear translocation of beta-catenin may play an important role in this process.

No abstract

There is accumulating evidence that high levels of dietary iron may play a role in colon carcinogenesis. We used a mouse model to investigate the impact of elevated dietary iron on incidence of aberrant crypt foci (ACF; a preneoplastic lesion) on tumor formation and on induction of oxidative stress. A/J mice were injected intraperitoneally, once a week for 6 weeks, with the colonotropic carcinogen, azoxymethane (AOM) or saline (vehicle controls). Following AOM or saline treatments, mice were placed on diets of high (3,000 ppm) and low (30 ppm) iron. Mice in each treatment group were sacrificed at 6 and 10 weeks following the final injection with AOM or saline. Colons were removed for subsequent histopathological analysis, which revealed average increases of 4.6 +- 1.3 vs. 10.4 +- 2.5 total tumors at 6 weeks and 30.75 +- 2.7 vs. 41.5 +- 4.4 total tumors at 10 weeks per AOM-treated mouse on low- and high-iron diets, respectively. There were no significant differences in incidence of ACF attributable to iron, although there was a trend toward greater crypt multiplicity per focus in mice on high-iron diets. Notably, no tumors were observed in mice receiving vehicle control injections in place of carcinogen, regardless of the level of dietary iron. These data suggest that iron exerts its effect at the stage of tumor promotion, but is not sufficient to initiate tumor formation. To learn more about mechanisms by which iron promotes tumor growth, colons were assayed for several biomarkers of oxidative stress [BOS; total F2-isoprostanes (F2-IsoPs), 15-F2t-isoprostanes (8-IsoPGF2s), Isofurans (IsoFs), and 8-hydroxyguanosines (8-OH[d]Gs)], as well as iron absorption, programmed cell death, and cellular proliferation. Elevated PCNA and TUNEL staining of the colon epithelium revealed hyperproliferative and apoptotic responses to iron, while no significant differences between iron groups were observed in each of the BOS that were assayed. Our results suggest that, following carcinogen exposure, elevated dietary iron promotes the growth of tumors with altered cellular homeostasis through a mechanism that is independent of oxidative stress.

Colon cancers often display perturbations in arachidonic acid metabolism, with elevated levels of cyclooxygenase (COX)-2 expression and prostaglandin E 2 (PGE 2 ) production frequently observed. Whereas COX-2 and PGE 2 are associated with cancer cell survival and tumor angiogenesis, arachidonic acid itself is a strong apoptotic signal that may facilitate cancer cell death. To further explore how cancer cells exploit the progrowth actions of prostaglandins while suppressing the proapoptotic actions of intracellular arachidonic acid, we determined the cytoplasmic phospholipase A 2 (cPLA 2 ) and COX-2 expression levels in a panel of human colon tumors by immunohistochemistry. Although high levels of cPLA 2 and COX-2 expression are predicted to facilitate maximal prostaglandin production, tumors frequently displayed a high-COX-2/low-cPLA 2 phenotype. The least represented phenotype was the high expression of cPLA 2 , a characteristic predicted to generate the highest levels of intracellular arachidonic acid. The potential proapoptotic role of cPLA 2 was supported by a higher frequency of terminal deoxynucleotidyl transferasemediated nick end labeling staining in cPLA 2 -positive tumors. Moreover, analysis of preneoplastic aberrant crypt foci from high-risk patients suggests that acquisition of the high-COX-2/low-cPLA 2 phenotype may arise at an early stage of colon carcinogenesis. We additionally inhibited cPLA 2 in HT-29 cells using antisense oligonucleotides. Our results indicate that cPLA 2 plays an important role in tumor necrosis factor a a a --induced apoptosis in human colon cancer cells. Our data further support the model in which colon cancer growth is favored when intracellular arachidonic acid levels are suppressed by inhibition of cPLA 2 or by a high-COX-2/low-cPLA 2 phenotype.

rATG induction in living donor renal transplantation is safe and associated with a low incidence of acute rejection and posttransplantation complications.

This report describes the results of 2 international randomized trials (total of 508 kidney transplant recipients). The primary objective was to assess the noninferiority of rabbit anti‐thymocyte globulin (rATG, Thymoglobulin®) versus interleukin‐2 receptor antagonists (IL2RAs) for the quadruple endpoint (treatment failure defined as biopsy‐proven acute rejection, graft loss, death, or loss to follow‐up) to serve as the pivotal data for United States (US) regulatory approval of rATG. The pooled analysis provided an incidence of treatment failure of 25.1% in the rATG and 36.0% in the IL2RA treatment groups, an absolute difference of −10.9% (95% confidence interval [CI] −18.8% to −2.9%) supporting noninferiority (noninferiority margin was 10%) and superiority of rATG to IL2RA. In a meta‐analysis of 7 trials comparing rATG with an IL2RA, the difference in the proportion of patients with BPAR at 12 months was −4.8% (95% CI −8.6% to −0.9%) in favor of rATG. In conclusion, a rigorous reanalysis of patient‐level data from 2 prior randomized, controlled trials comparing rATG versus IL‐2R monoclonal antibodies provided support for regulatory approval for rATG for induction therapy in renal transplant, making it the first T cell–depleting therapy approved for the prophylaxis of acute rejection in patients receiving a kidney transplant in the United States.