The immunomodulatory effect of oral NaHCO3 is mediated by the splenic nerve: multivariate impact revealed by artificial neural networks.

Stimulation of the inflammatory reflex (IR) is a promising strategy for treating systemic inflammatory disorders. Recent studies suggest oral sodium bicarbonate (NaHCO3) as a potential activator of the IR, offering a safe and cost-effective treatment approach. However, the mechanisms underlying NaHCO3-induced anti-inflammatory effects remain unclear. We investigated whether oral NaHCO3's immunomodulatory effects are mediated by the splenic nerve. Female rats received NaHCO3 or water (H2O) for four days, and splenic immune markers were assessed using flow cytometry. NaHCO3 led to a significant increase (p < 0.05, and/or partial eta squared > 0.06) in anti-inflammatory markers, including CD11bc + CD206 + (M2-like) macrophages, CD3 + CD4 + FoxP3 + cells (Tregs), and Tregs/M1-like ratio. Conversely, proinflammatory markers, such as CD11bc + CD38 + TNFα + (M1-like) macrophages, M1-like/M2-like ratio, and SSChigh/SSClow ratio of FSChighCD11bc + cells, decreased in the spleen following NaHCO3 administration. These effects were abolished in spleen-denervated rats, suggesting the necessity of the splenic nerve in mediating NaHCO3-induced immunomodulation. Artificial neural networks accurately classified NaHCO3 and H2O treatment in sham rats but failed in spleen-denervated rats, highlighting the splenic nerve's critical role. Additionally, spleen denervation independently influenced Tregs, M2-like macrophages, Tregs/M1-like ratio, and CD11bc + CD38 + cells, indicating distinct effects from both surgery and treatment. Principal component analysis (PCA) further supported the separate effects. Our findings suggest that the splenic nerve transmits oral NaHCO3-induced immunomodulatory changes to the spleen, emphasizing NaHCO3's potential as an IR activator with therapeutic implications for a wide spectrum of systemic inflammatory conditions.

On the Influence of Viscoelastic Modeling in Fluid Flow Simulations of Gum Acrylonitrile Butadiene Rubber.

Computational fluid dynamics (CFD) simulation is an important tool as it enables engineers to study different design options without a time-consuming experimental workload. However, the prediction accuracy of any CFD simulation depends upon the set boundary conditions and upon the applied rheological constitutive equation. In the present study the viscoelastic nature of an unfilled gum acrylonitrile butadiene rubber (NBR) is considered by applying the integral and time-dependent Kaye-Bernstein-Kearsley-Zapas (K-BKZ) rheological model. First, exhaustive testing is carried out in the linear viscoelastic (LVE) and non-LVE deformation range including small amplitude oscillatory shear (SAOS) as well as high pressure capillary rheometer (HPCR) tests. Next, three abrupt capillary dies and one tapered orifice die are modeled in Ansys POLYFLOW. The pressure prediction accuracy of the K-BKZ/Wagner model was found to be excellent and insensitive to the applied normal force in SAOS testing as well as to the relation of first and second normal stress differences, provided that damping parameters are fitted to steady-state rheological data. Moreover, the crucial importance of viscoelastic modeling is proven for rubber materials, as two generalized Newtonian fluid (GNF) flow models severely underestimate measured pressure data, especially in contraction flow-dominated geometries.

Infectious disease considerations in immunocompromised patients.

Immunocompromised patients account for about 3% of the US population. Complications arising from infection are common in these patients and can present diagnostic and therapeutic challenges. This article describes the pathophysiology of immunosuppression in five common immunocompromised states-asplenia, HIV infection, solid organ transplant, biologic use, and cancer-as well as specific infectious risks and considerations for affected patients and how to manage them.

Reliability and Validity of National End of Rotation Examinations: An Update.

PURPOSE: This study sought to evaluate the reliability of the PAEA End of Rotation™ exam scores used as a combined scale. The study also investigated how closely the individual exam scores and the combined scale correlate with Physician Assistant National Certifying Exam (PANCE) performance to validate their use as tools for assessing physician assistant (PA) students during their clinical training. METHODS: Deidentified PAEA End of Rotation examination and PANCE scores were used to calculate Pearson correlations, Cronbach's alpha, and value of Cronbach's alpha if individual exams were removed from the analysis. A linear regression model was generated to predict certification exam scores. RESULTS: End of Rotation examinations are a reliable predictor of certification examination performance independent of PA program or test version, with Cronbach's alpha at 0.847. CONCLUSIONS: The mean of all 7 examinations may be used, but the mean of just 4 examinations (Emergency Medicine, Family Medicine, General Surgery, and Internal Medicine) is also a valid predictor of certification examination performance.

Immune checkpoint inhibitors in malignancies with mismatch repair deficiency: a review of the state of the current knowledge.

The use of immune checkpoint inhibitors to treat malignant tumors with microsatellite instability is an emerging new modality. This is based on the observations that these tumors may have a high mutation rate-thus a potential source of tumor-specific neoantigens-and harbor infiltrating cytotoxic T cells in response, suggesting that they may be particularly susceptible to immune checkpoint therapy. PUBMED and ASCO library were systematically reviewed to identify all relevant data that involved the use of immune checkpoint inhibitors in the treatment of cancers with microsatellite instability. The manual search retrieved a total of 3 relevant articles and 1 abstract published between 2015 and 2016. A total of 61 patients with colorectal, 3 with ampullary/cholangiocarcinoma, 2 with endometrial carcinomas, 3 with small bowel cancers, 2 with glioblastoma multiforme, and 1 with bladder cancer with reported efficacy results were reviewed. All the patients had stage IV cancer and were treated with immune checkpoint inhibitors until progression of disease or intolerable side effects emerged. The range of objective response rate was 25-71%. Responses were also durable with progression-free survival at 20 weeks of around 67-78% and to 46% at 1 year. The use of immune checkpoint inhibitors is effective in cancers that express microsatellite instability.

Ileal immune dysregulation in necrotizing enterocolitis: role of CD40/CD40L in the pathogenesis of disease.

OBJECTIVES: CD40, a co-stimulatory molecule, plays a critical role in coordinating enteric inflammatory immune responses. In necrotizing enterocolitis (NEC), upregulation of IL-10, a CD40-modulated cytokine, has been described, but the role of the IL-10 receptor (IL-10Rß), CD40, and its ligand CD40L in disease pathogenesis is unknown. The study herein investigates ileal expression of CD40, CD40L, and IL-10R in a rat model of NEC. SUBJECTS AND METHODS: NEC was induced in newborn rats using established methods of formula feeding, asphyxia, and cold stress. Expression of CD40, CD40L, IL-10Rß, and other proinflammatory molecules, including Toll-like receptor-4 (TLR-4) and IL-18, was assessed by immunoblotting. Tissue infiltration by macrophages, monocytes, and T cells was examined by confocal immunohistochemistry. RESULTS: Ileum from rat pups with NEC showed increased expression of TLR-4, IL-18, and IL-10Rß. Sections from both NEC and control pups demonstrated preservation of ileal cells expressing CD40/CD40L. The distal ileum of controls expressed both CD40 and CD40L; conversely, neither molecule was detected in ileal tissue from NEC pups. Additional studies showed that treatment with epidermal growth factor (EGF), previously shown to ameliorate the severity of NEC in an animal model, did not restore CD40 expression. CONCLUSIONS: Ileal cytokine dysregulation, manifested by decreased CD40/CD40L and increased IL-10Rß expression, may be involved in the pathogenesis of NEC. Dampened CD40 signaling may be related to enhanced IL-10 expression and a suppressed T-cell response to injury. We speculate that augmenting CD40-CD40L interactions may achieve a protective effect in this NEC model.

Multiple levels of selection responsive to immunoglobulin light chain and heavy chain structures impede the development of Dmu-expressing B cells.

The truncated/V(H)-less mouse H chain Dmu forms precursor B cell receptors with the surrogate L chain complex that promotes allelic exclusion but not other aspects of pre-B cell development, causing most progenitor B cells expressing this H chain to be eliminated at the pre-B cell checkpoint. However, there is evidence that Dmu-lambda1 complexes can be made and are positively selected during fetal life but cannot sustain adult B lymphopoiesis. How surrogate and conventional L chains interpret Dmu's unusual structure and how that affects signaling outcome are unclear. Using nonlymphoid and primary mouse B cells, we show that secretion-competent lambda1 L chains could associate with both full-length H chains and Dmu, whereas secretion-incompetent lambda1 L chains could only do so with full-length H chains. In contrast, Dmu could not form receptors with a panel of kappa L chains irrespective of their secretion properties. This was due to an incompatibility of Dmu with the kappa-joining and constant regions. Finally, the Dmu-lambda1 receptor was less active than the full-length mouse mu-lambda1 receptor in promoting growth under conditions of limiting IL-7. Thus, multiple receptor-dependent mechanisms operating at all stages of B cell development limit the contribution of B cells with Dmu H chain alleles to the repertoire.

Sphingomyelin synthase 2 deficiency attenuates NFkappaB activation.

BACKGROUND: NFkappaB has long been regarded as a proatherogenic factor, mainly because of its regulation of many of the proinflammatory genes linked to atherosclerosis. Metabolism of sphingomyelin (SM) has been suggested to affect NFkappaB activation, but the mechanism is largely unknown. SMS2 regulates SM levels in cell plasma membrane and lipid rafts and has a potential to regulate NFkappaB activation. METHODS AND RESULTS: To investigate the role of SMS2 in NFkappaB activation we used macrophages from SMS2 knockout (KO) mice and SMS2 siRNA-treated HEK 293 cells. We found that NFkappaB activation and its target gene expression are attenuated in macrophages from SMS2 KO mice in response to lipopolysaccharide (LPS) stimulation and in SMS2 siRNA- treated HEK 293 cells after tumor necrosis factor (TNF)-alpha simulation. In line with attenuated NFkappaB activation, we found that SMS2 deficiency substantially diminished the abundance of toll like receptor 4 (TLR4)-MD2 complex levels on the surface of macrophages after LPS stimulation, and SMS2 siRNA treatment reduced TNF-alpha-stimulated lipid raft recruitment of TNF receptor-1 (TNFR1) in HEK293 cells. SMS2 deficiency decreased the relative amounts of SM and diacylglycerol (DAG) and increased ceramide, suggesting multiple mechanisms for the decrease in NFkappaB activation. CONCLUSIONS: SMS2 is a modulator of NFkappaB activation, and thus it could play an important role in NFkappaB-mediated proatherogenic process.

In vitro models of acute and long-term continuous infection of human respiratory epithelial cells with Chlamydophila pneumoniae have opposing effects on host cell apoptosis.

Persistent infection with the obligate intracellular pathogen Chlamydophila pneumoniae has been implicated in the pathogenesis of many chronic diseases, but its mechanism remains unclear. Many pathogens have been found to modulate cellular apoptosis in order to survive and multiply. Chlamydial species were shown to both induce and inhibit host cell apoptosis depending on the experimental conditions. We utilized in vitro models of acute and long-term continuous (LTC) infection with the same cell line (HEp-2) and chlamydial isolate (TW-183) used in both models. Host cell apoptosis in infected and uninfected cells was assessed by fluorescence microscopy and flow cytometry. While acute infection induced apoptosis 72 h post-infection, LTC-infected cells had low rates of apoptosis and showed resistance to different exogenous inducers of apoptosis (sorbitol, serum withdrawal, hydrogen peroxide) when compared to uninfected cells. Chronicity of infection appears to be a critical factor in the modulation of host cell apoptosis by C. pneumoniae. Induction of apoptosis may help to propagate the infection, while inhibition of apoptosis could help protect the organism in chronic infection.

Transcription factors TFE3 and TFEB are critical for CD40 ligand expression and thymus-dependent humoral immunity.

TFE3 and TFEB are broadly expressed transcription factors related to the transcription factor Mitf. Although they have been linked to cytokine signaling pathways in nonlymphoid cells, their function in T cells is unknown. TFE3-deficient mice are phenotypically normal, whereas TFEB deficiency causes early embryonic death. We now show that combined inactivation of TFE3 and TFEB in T cells resulted in a hyper-immunoglobulin M syndrome due to impaired expression of CD40 ligand by CD4(+) T cells. Native TFE3 and TFEB bound to multiple cognate sites in the promoter of the gene encoding CD40 ligand (Cd40lg), and maximum Cd40lg promoter activity and gene expression required TFE3 or TFEB. Thus, TFE3 and TFEB are direct, physiological and mutually redundant activators of Cd40lg expression in activated CD4(+) T cells critical for T cell-dependent antibody responses.

Precursor B cell receptor signaling activity can be uncoupled from surface expression.

Signals from the precursor BCR (preBCR) cause proliferation and differentiation of progenitor (pro-) B cells into pre-B cells. Given the very low amounts of surface preBCRs and the demonstrated cell autonomy of preBCR signaling, we examined the possible occurrence of preBCR signal propagation from intracellular membranes such as the endoplasmic reticulum (ER) and the trans-Golgi network (TGN) in transformed and primary pro-B cells. PreBCRs composed of normal Ig mu or truncated Dmu heavy chains (HCs) were redirected to intracellular sites via localization sequences appended to the HC cytoplasmic tail. PreBCR complexes retained in the TGN or shunted from the TGN to lysosomes were as or 50% as active as the corresponding wild-type preBCRs in directing preBCR-dependent events, including CD2 and CD22 expression and proliferation in primary pro-B cells. This occurred despite their low to undetectable surface expression in transformed cells, which otherwise allowed significant surface accumulation of wild-type preBCRs. In contrast, ER-retained preBCRs were inactive. These results suggest that preBCR signaling is remarkably tolerant of dramatic changes in its subcellular distribution within post-ER compartments and support the possibility that the preBCR can activate signaling pathways in the TGN as well as the plasma membrane.

Renal carcinoma-associated transcription factors TFE3 and TFEB are leukemia inhibitory factor-responsive transcription activators of E-cadherin.

Translocations of the genes encoding the related transcription factors TFE3 and TFEB are almost exclusively associated with a rare juvenile subset of renal cell carcinoma and lead to overexpression of TFE3 or TFEB protein sequences. A better understanding of how deregulated TFE3 and TFEB contribute to the transformation process requires elucidating more of the normal cellular processes in which they participate. Here we identify TFE3 and TFEB as cell type-specific leukemia inhibitory factor-responsive activators of E-cadherin. Overexpression of TFE3 or TFEB in 3T3 cells activated endogenous and reporter E-cadherin expression. Conversely, endogenous TFE3 and/or TFEB was required for endogenous E-cadherin expression in primary mouse embryonic fibroblasts and human embryonic kidney cells. Chromatin precipitation analyses and E-cadherin promoter reporter gene assays revealed that E-cadherin induction by TFE3 or TFEB was primarily or exclusively direct and mitogen-activated protein kinase-dependent in those cell types. In mouse embryonic fibroblasts, TFE3 and TFEB activation of E-cadherin was responsive to leukemia inhibitory factor. In 3T3 cells, TFE3 and TFEB expression also induced expression of Wilms' tumor-1, another E-cadherin activator. In contrast, E-cadherin expression in model mouse and canine renal epithelial cell lines was indifferent to inhibition of endogenous TFE3 and/or TFEB and was reduced by TFE3 or TFEB overexpression. These results reveal new cell type-specific activities of TFE3 and TFEB which may be affected by their mutation.

The unique region of surrogate light chain component lambda5 is a heavy chain-specific regulator of precursor B cell receptor signaling.

Signals transduced by precursor-BCRs (pre-BCRs) composed of Ig mu heavy chains (HCs) and the surrogate L chain components lambda5 and VpreB are critical for B cell development. A conserved unique region (UR) of lambda5 was shown to activate pre-BCR complexes in transformed cells and to engage putative ligands, but its contribution to pre-B cell development is not known. It is also not clear why the lambda-like sequences in lambda5 are used to select HCs that will associate mainly with kappa L chains. In this study, we show that, in transformed and primary mouse B cell progenitors, receptors containing full-length HCs and lacking the lambda5UR were expressed at higher surface levels, but exhibited reduced activity compared with normal pre-BCRs in supporting developmental changes that accompany the progenitor to pre-B cell transition in primary cell culture systems and in the bone marrow in vivo. In contrast, deletion of the lambda5UR did not change net signaling output by the Dmu-pre-BCR, a developmentally defective receptor that exhibited impaired activity in the primary cell culture system. Moreover, the lambda-like sequences in lambda5 were more accommodating than kappa in supporting surface expression and signaling by the different HCs. These results show that the lambda5UR is important, although not essential, for surrogate L chain-dependent receptor signaling in primary cells, and furthermore may help allow discrimination of signaling competency between normal and Dmu-pre-BCRs. That the lambda-like portion of lambda5 in the absence of the UR was nondiscriminatory suggests that the lambda5UR focuses pre-BCR-dependent selection on the HC V region.

Incremental value of fusion imaging with integrated PET-CT in oncology.

PURPOSE: The purpose of this study was to assess the incremental value of integrated F-18 FDG PET-CT imaging compared with either alone for evaluation of patients with body malignancies. MATERIALS AND METHODS: Images from 173 consecutive patients with body malignancies referred for integrated PET-CT imaging were reviewed. A CT with contrast performed within 2 months of PET-CT was available for 74 patients. RESULTS: There was agreement between the transmission CT (TrCT) and PET interpreted separately in 65% (112 of 173) of patients. Interpretation of integrated PET-CT had an incremental diagnostic value in 17.9% (31 of 173) of the total patient population. Data was analyzed further excluding patients for whom further analysis was not relevant: 1) 20% (34 of 173) of patients with normal TrCT and PET and 2) 11% (19 of 173) of patients with disseminated metastases (too numerous to count) on both TrCT and PET. Among the 120 other patients, PET interpreted alone was positive in 195 body regions and CT-positive in 178 body regions with agreement for all regions in 49% (59 of 120) of patients and discordance or equivocal lesions in 51% (61 of 120) of patients. Integrated PET-CT had an incremental diagnostic value in 27% (31 of 120) of patients. Contrasted CT scan demonstrated hepatic lesions in 5 and extrahepatic lesions in 3 patients overlooked on TrCT; all 8 of these lesions were PET-positive. There was incremental impact on the management of 12.5% (15 of 120) of patients. CONCLUSIONS: After excluding patients with a normal PET-CT or disseminated disease, there was an incremental diagnostic value of integrated PET-CT imaging in 27% (31 of 120) and incremental impact on management in 12.5% (15 of 120) of patients. CT with contrast did not demonstrate lesions not appreciated by PET-CT.

Defective thymocyte maturation by transgenic expression of a truncated form of the T lymphocyte adapter molecule and Fyn substrate, Sin.

Adapter molecules that promote protein-protein interactions play a central role in T lymphocyte differentiation and activation. In this study, we examined the role of the T lymphocyte-expressed adapter protein and Src kinase substrate, Sin, on thymocyte function using transgenic mice expressing an activated, truncated allele of Sin (SinDeltaC). We found that SinDeltaC expression led to reduced numbers of CD4(+) and CD8(+) single-positive cells and reduced thymic cellularity due to increased thymocyte apoptosis. Because the adapter properties of Sin are mediated by tyrosine-based motifs and given that Sin is a substrate for Src tyrosine kinases, we examined the involvement of these kinases in the inhibitory effects of SinDeltaC. We found that in transgenic thymocytes, SinDeltaC was constitutively phosphorylated by the Src kinase Fyn, but not by the related kinase Lck. Using SinDeltaC and fyn(-/-) animals, we also found that the expression of Fyn was required for the inhibitory effect of SinDeltaC on thymocyte apoptosis but not for SinDeltaC-mediated inhibition of T cell maturation. The inhibitory effect of SinDeltaC on thymocyte maturation correlated with defective activation of the mitogen-activated protein kinase extracellular signal-regulated kinase. Our results suggest that the Sin mutant inhibits thymocyte differentiation through Fyn-dependent and -independent mechanisms and that endogenous Sin may be an important regulator of thymocyte development.

Vascular endothelial growth factor-mediated angiogenesis inhibition and postoperative wound healing in rats.

BACKGROUND: Vascular endothelial growth factor (VEGF) is an angiogenic factor that acts by binding to specific high-affinity tyrosine kinase receptors. SU5416 is an antiangiogenic agent that acts as a potent and selective inhibitor of the VEGF Flk-1/KDR receptor tyrosine kinase. SU5416 has been shown to inhibit VEGF-dependent mitogenesis of human endothelial cells and to decrease the growth of xenografts of melanoma, lung carcinoma, ovarian carcinoma, and gliomas. The effect of pre- or perioperative use of this drug on angiogenesis and wound healing in the postoperative setting has not been shown. We sought to analyze the efficacy and safety with respect to functional dosing of SU5416 in the setting of wound healing. This represents an important step forward in the use of this and similar drugs in the perioperative setting of treatment for multiple types of cancers. The use of an inhibitor of VEGF receptors such as SU5416 is distinct and it is likely complementary to other agents in the treatment of such cancers. METHODS: We injected 8-week-old male Sprague-Dawley rats with SU5416 (8 or 12 mg/kg) or dimethyl sulfoxide intraperitoneally, daily for 14 days. We then performed a right pulmonary lobectomy and 6-mm full-thickness punch biopsies of the back. Tissue perfusion measured via laser Doppler on Postoperative Day 2 was 1.65, 1.22, and 1.14 perfusion units (P < 0.0004) for control, 8 mg/kg, and 12 mg/kg groups, respectively. RESULTS: We successfully treated a murine model with functional doses of the anti-VEGF drug SU5416 so as to achieve decreased vascularity and blood flow in postoperative wounds. There was no effect on gross wound healing or infection in either control or treatment groups. Also, no drug-related impairment of histologic healing or decrease in wound tensile strength was demonstrated at either 6 or 14 days. CONCLUSION: Preoperative therapy with functional dosing of SU5416 does not appear to have any major effect on postoperative morbidity or mortality in rats. We additionally conclude that preoperative therapy with SU5416 should be investigated further with careful attention to wound integrity.

Induction of cyclooxygenase-2 and invasiveness by transforming growth factor-beta(1) in immortalized mouse colonocytes expressing oncogenic Ras.

Cyclooxygenase-2 (COX-2) expression appears to be important in colorectal carcinogenesis. Elevated COX-2 expression and activity have been observed in several different transformed cell types. Prior studies implicating involvement of the Ras oncogene and growth factors on COX-2 expression were largely derived from rat small intestinal cell lines. We have investigated whether mouse colonocyte COX-2 levels are regulated by oncogenic Ras or transforming growth factor-beta(1) (TGF-beta(1)), and whether these factors also serve to regulate cellular invasiveness. Young adult mouse colonocyte cells are colonocytes derived from the "Immortomouse" and immortalized by the SV40 large T antigen. Young adult mouse colonocyte Ras cells were derived by transfection of young adult mouse colonocyte cells with oncogenic Ha-Ras and are known to be tumorigenic. We found that the induction of COX-2 and eicosanoid release were augmented in the presence of activated Ras and that TGF-beta(1) caused a further increase in COX-2 in the Ras-transformed mouse colonocytes. Increased COX-2 expression was correlated with increased release of prostaglandins E(2) and I(2). Activated Ras and TGF-beta increased the invasiveness of the young adult mouse colonocyte cells, but treatment with a COX-2 inhibitor did not inhibit invasiveness. Thus we found that transforming growth factor-beta collaborates to increase COX-2 expression, protaglandin release, and invasiveness in mouse colonocytes, but the increased COX-2 activity does not appear to contribute to the invasive response.

Operative technique for safe pulmonary lobectomy in Sprague-Dawley rats.

To perform safe and effective animal surgery, it is essential to follow a well- disciplined approach. We recently have embarked on a variety of wound-healing studies that involve multiple operative techniques including thoracotomy with lobectomy. Such procedures require specific attention to effective anesthesia and ventilation as well as a structured and safe approach to the actual procedure. We have developed operative techniques for thoracotomy and pulmonary lobectomy that limit animal morbidity and mortality. Using general anesthesia, we safely and effectively completed right thoracotomy and pulmonary lobectomy in 51 of the 54 (>94%) of the Sprague-Dawley rats that were our subjects. We effectively ventilated the animals with inhalation anesthesia, avoiding the need for endotracheal intubation. The three mortalities occurred during early experiments and were attributable to easily identified technical errors. Our animals did not experience postoperative respiratory complications. Postoperative recovery was excellent, and no appreciable postoperative morbidity was encountered.

New strategies for colorectal cancer prevention and treatment.

Colorectal cancer (CRC) is the second most common fatal malignancy in the Western world, with more than 150,000 new cases accounting for 55,000 deaths in the United States every year. Surgical resection is an effective treatment for localized disease, achieving a 5-year survival rate of 90%; but chemotherapy and other novel treatments for metastatic disease remain ineffective. There have been significant efforts to identify risk factors associated with the development of CRC and to explore potential preventive therapies. Both genetic and epigenetic factors contribute to the development of colorectal cancer. Specific genetic changes in proto-oncogenes, tumor suppressor genes, and DNA mismatch repair genes have led to a genetic model of CRC. Cooperative genetic aberrations involving APC (adenomatous polyposis coli), beta-catenine, K-ras, and p53 are involved in the multistep adenoma-carcinoma sequence of CRC. Emerging data have implicated cyclooxygenase-2 (COX-2) and prostanoid production in the pathogenesis of colorectal carcinoma. Several reports indicate a close relation between the intake of nonsteroidal antiinflammatory drugs (NSAIDs) and a decreased risk for developing colorectal cancer. Epidemiologic studies indicate a 40% to 50% reduction in mortality due to colorectal cancer in individuals taking NSAIDs (e.g., aspirin). Epigenetic factors including age, diet, angiogenesis, and immune responses also appear to contribute to the development of CRC. Combining knowledge of the genetic and epigenetic events implicated in this disease may allow a broader understanding of the pathogenesis of CRC. These developments may yield benefits in earlier detection and in the design of better antitumor interventions.