Paclitaxel (PTX), a microtubule-active drug, causes mitotic arrest leading to apoptosis in certain tumor cell lines. Here we investigated the effects of PTX on human arterial smooth muscle cell (SMC) cells. In SMC, PTX caused both (a) primary arrest in G 1 and (b) post-mitotic arrest in G 1 . Post-mitotic cells were multinucleated (MN) with either 2C (near-diploid) or 4C (tetraploid) DNA content. At PTX concentrations above12 ng/ml, MN cells had 4C DNA content consistent with the lack of cytokinesis during abortive mitosis. Treatment with 6-12 ng/ml PTX yielded MN cells with 2C DNA content. Finally, 1-6 ng/ml of PTX, the lowest concentrations that affected cell proliferation, caused G 1 arrest without multinucleation. It is important that PTX did not cause apoptosis in SMC. The absence of apoptosis could be explained by mitotic exit and G 1 arrest as well as by low constitutive levels of caspase expression and by p53 and p21 induction. Thus, following transient mitotic arrest, SMC exit mitosis to form MN cells. These post-mitotic cells were subsequently arrested in G 1 but maintained normal elongated morphology and were viable for at least 21 days. We conclude that in SMC PTX causes post-mitotic cell cycle arrest rather than cell death.

Overexpression and amplification of the c-myc oncogene occur in approximately 70 and 10% of human primary colorectal carcinomas, respectively, indicating the importance of this gene in colorectal tumorigenesis. Little, however, is known about the involvement of c-myc in the progression of colorectal cancer. We therefore determined c-myc gene expression and amplification in a group of primary tumors and metastases from patients with colorectal cancer using quantitative PCR-based tests. While the percentage of metastases over-expressing c-myc (13/26 =50%) was in the same range as reported for primary tumors by others, gene amplification of c-myc was significantly (p = 0.001) more frequent in metastases (16/27 = 59%) compared to primary tumors (1/23 = 4%) in our series. Interestingly, in 23 metastases where both expression and amplification of c-myc could be determined, there was no correlation between gene copy number and expression level (p = 0.18; r = 0.19). We conclude that amplification but not overexpression of c-myc is related to metastatic progression of colorectal cancer and that overexpression of c-myc is driven by mechanisms other than the number of c-myc copies in the tumors studied.

Objective-Advances in stent technology have enabled the delivery of drugs to improve outcomes after stent deployment.However, the optimal payloads for stents are not clear, and the appropriate stent-based therapies for high-risk patients, such as diabetics, have not been clearly established. Methods and Results-We used smooth muscle cell culture models to compare the activities of rapamycin and paclitaxel.Smooth muscle cells were grown in normal or high glucose to induce insulin resistance. Both paclitaxel and rapamycin activate mitogen-activated protein kinase pathways similarly. However, rapamycin potently activates AKT-dependent signaling, an effect that overrides the downregulation of this pathway by insulin resistance and that causes phosphorylation of the AKT-dependent transcription factor FOXO1. This effect is associated with attenuation of the anti-migratory effects of rapamycin under high glucose conditions that are not observed with paclitaxel, as well as with increased protection against ceramide-induced cytotoxicity, both of which are dependent on FOXO1 phosphorylation. Conclusions-Differences between the ability of rapamycin and paclitaxel to activate AKT may account for their differential cell survival and antichemotactic activities. These observations may provide a basis for understanding clinical differences between rapamycin-and paclitaxel-coated stents. The approaches used in these studies can be expanded to other candidate stent payloads as a method for triage in preclinical studies. Key Words: migration Ⅲ signaling Ⅲ smooth muscle Ⅲ stent Ⅲ viability C are for patients with symptomatic or unstable coronary artery disease has undergone a major evolution over the past 5 years, with shifts toward increased use of percutaneous stent implantation at the expense of thrombolytic therapy and coronary artery bypass grafting. Since the introduction of coronary artery angioplasty in the late 1970s by Andreas Greuntzig, the development of percutaneous coronary interventions has been punctuated by several major breakthroughs, including those that have transformed the field (eg, the use of stents to prevent vessel recoil) and some that have not (percutaneous atherectomy being a notable example). Although each of the major advances in interventional cardiology has been considered a threat to surgical approaches, only the introduction of drug-eluting stents to clinical practice has coincided with a reduction in coronary artery bypass procedures. 1 Nevertheless, with Ͼ1 million procedures performed per year and with stents being deployed in more patients and in more vessels per patient, the problem of restenosis has not been eliminated, and many questions remain about the optimal technology platform for percutaneous interventions.Restenosis after percutaneous interventions has 2 principle components: vessel remodeling and intimal hyperplasia. Stent deployment essentially obviates the problem of remodeling by preventing chronic recoil mechanisms. 2 Drug-eluting stents have been developed on the premise that ph...

SummaryTo reduce the thrombogenic properties of coronary artery stents, a biodegradable polylactic acid (PLA) stent coating with an incorporated thrombin inhibitor and a platelet aggregation inhibitor has been developed. In an ex vivo human stasis model, its effect on platelets, plasmatic coagulation and its release characteristics were studied using whole blood. Bare steel and bare gold-surface stents were compared to steel and gold-surface stents coated with PLA (30 kDa) containing 5% polyethyleneglycol (PEG)-hirudin and 1% iloprost, with an empty tube as control. Markers of activated coagulation (prothrombin fragment F1-2 and thrombin-antithrombin III complex, TAT), were assayed and the release of drugs from the coating was assessed by aPTT and collagen-induced platelet aggregation. Bare steel and gold stents were completely covered by a blood clot, and high levels of coagulation markers (F1-2 fragment and TAT) were detected. No differences in the thrombogenic properties were found between bare gold or steel stents. Coated stents were free of blood clots and only minor elevations of markers were detected. Release data from in-vitro studies over 90 days showed a gradual release of the drugs with an initial exponential release characteristic for PEG-hirudin, slow release of iloprost and a 10% degradation of the PLA carrier. This drug releasing biodegradable coating effectively reduced thrombus formation independent of the metallic surface.

This study provides the first empirical evidence that the application of the posttraumatic stress disorder paradigm in the long-term evaluation of cardiac arrest survivors significantly contributes to defining a patient population at high risk for serious emotional disability.