The serine protease inhibitor serpinE2 is a novel target of ERK signaling involved in human colorectal tumorigenesis

<p>Abstract</p> <p>Background</p> <p>Among the most harmful of all genetic abnormalities that appear in colorectal cancer (CRC) development are mutations of KRAS and its downstream effector BRAF as they result in abnormal extracellular signal-related kinase (ERK) signaling. In a previous report, we had shown that expression of a constitutive active mutant of MEK1 (caMEK) in normal rat intestinal epithelial cells (IECs) induced morphological transformation associated with epithelial to mesenchymal transition, growth in soft agar, invasion and metastases in nude mice. Results from microarrays comparing control to caMEK-expressing IECs identified the gene encoding for serpinE2, a serine protease inhibitor, as a potential target of activated MEK1.</p> <p>Results</p> <p>1- RT-PCR and western blot analyses confirmed the strong up-regulation of serpinE2 expression and secretion by IECs expressing oncogenic MEK, Ras or BRAF. 2- Interestingly, serpinE2 mRNA and protein were also markedly enhanced in human CRC cells exhibiting mutation in <it>KRAS </it>and <it>BRAF</it>. 3- RNAi directed against serpinE2 in caMEK-transformed rat IECs or in human CRC cell lines HCT116 and LoVo markedly decreased foci formation, anchorage-independent growth in soft agarose, cell migration and tumor formation in nude mice. 4- Treatment of CRC cell lines with U0126 markedly reduced <it>serpinE2 </it>mRNA levels, indicating that expression of <it>serpinE2 </it>is likely dependent of ERK activity. 5- Finally, Q-PCR analyses demonstrated that mRNA levels of serpinE2 were markedly increased in human adenomas in comparison to healthy adjacent tissues and in colorectal tumors, regardless of tumor stage and grade.</p> <p>Conclusions</p> <p>Our data indicate that serpinE2 is up-regulated by oncogenic activation of Ras, BRAF and MEK1 and contributes to pro-neoplastic actions of ERK signaling in intestinal epithelial cells. Hence, serpinE2 may be a potential therapeutic target for colorectal cancer treatment.</p

La régulation du métabolisme du glucose par la protéine tyrosine phosphatase SHP-1

Lorsque l’insuline se lie à son récepteur, elle induit une cascade de réactions indispensables à l’utilisation du glucose. La résistance à l’insuline et le diabète de type 2 qui affectent une fraction croissante de la population résultent d’un défaut de signalisation de l’insuline. La voie de signalisation PI3K qu’emprunte l’insuline pour promouvoir l’utilisation du glucose est d’abord décrite en introduction de cette thèse. Aussi, il existe plusieurs mécanismes de désensibilisation qui sont essentiels pour limiter l’ampleur du signal à la réponse métabolique requise. Cependant, ces mécanismes sont altérables et de faibles dérèglements peuvent devenir responsables d’une propagation défaillante du signal insulinique. Les souris viable motheaten (mev), déficientes en activité SHP-1, nous ont permis au premier chapitre de démontrer que SHP-1 constitue un de ces mécanismes de désensibilisation. Ces souris montrent une plus grande tolérance au glucose et une meilleure sensibilité à l’insuline que les souris non-déficientes en SHP-1, ainsi qu’une meilleure signalisation de l’insuline dans le foie et le muscle squelettique. De plus, nous avons pu démontrer que SHP-1 contrôle aussi la clairance hépatique de l’insuline, importante pour réguler la concentration et la sensibilité systémique de l’insuline. Cette première étude a donc permis d’établir un nouveau rôle pour SHP-1 dans la régulation de l’action de l’insuline. Par la suite, il devenait primordial de décrire les mécanismes impliqués dans la sensibilisation à l’insuline par la déficience en SHP-1 dans le muscle et le foie. À l’aide d’adénovirus codant pour un mutant catalytiquement inerte de SHP-1 (DNSHP-1), nous rapportons au deuxième chapitre, par l’expression de DNSHP-1 dans les hépatocytes Fao, que la diminution de la production hépatique de glucose observée chez les souris mev résulte d’une augmentation de la glycogénèse plutôt que d’une diminution de la gluconéogenèse. Enfin, au dernier chapitre, DNSHP-1 exprimé dans les myocytes L6 favorise la signalisation via Akt, et accroît l’expression de GLUT4, le principal transporteur de glucose sensible à l’insuline. Ensemble, nos résultats suggèrent clairement que SHP-1 est un nouveau modulateur de l’action de l’insuline dans le foie et le muscle squelettique. SHP-1 pourrait donc représenter une nouvelle cible thérapeutique pour traiter le diabète de type 2.After binding to its receptor, insulin induces a reaction cascade that is essential for glucose utilization. Insulin resistance and type 2 diabetes are affecting an increasing portion of the population and result from insulin signaling impairment. Insulin signaling pathways promoting glucose utilization are reviewed in the introduction of the thesis, as well the desensitization mechanisms which are crucial to limit insulin signal duration and intensity. Viable motheaten (mev) mice, harboring a spontaneous mutation leading to SHP-1 activity deficiency, allowed us to demonstrate in chapter I that SHP-1 constitutes one of these desensitization mechanisms. Indeed, mev mice showed an increased glucose tolerance and insulin sensitivity as compared to wild type littermates, resulting from increased insulin signaling in liver and skeletal muscle. Moreover, we show that SHP-1 controls hepatic insulin clearance, which is important to control systemic insulin concentration and sensitivity. This first study thus establishes a novel role for SHP-1 in the regulation of insulin action and glucose homeostasis. Thereafter, it became primordial to describe cell autonomous mechanisms by which SHP-1 enhances insulin sensitivity in liver and muscle. In the second chapter, expression of DNSHP-1 using adenoviral gene transfer into Fao rat hepatoma cells indicates that decreased hepatic glucose production observed in mev mice is likely the result of enhanced glycogenesis rather than reduced gluconeogenesis. Finally, I show in the last chapter that DNSHP-1 expression in myocytes increased insulin signaling to Akt, and increased GLUT4 expression, the main insulin responsive glucose transporter. Together, our results clearly establish that SHP-1 is a new modulator of insulin action in liver and skeletal muscle. SHP-1 may represent a novel therapeutic target to combat type 2 diabetes

Exercise echocardiographic findings and outcome of patients referred for evaluation of dyspnea

AbstractObjectivesThe purpose of this study was to characterize the outcome of patients referred for exercise echocardiographic evaluation of dyspnea.BackgroundLittle information exists regarding outcome of patients with dyspnea.MethodsWe identified 443 patients with unexplained dyspnea, 2,033 with chest pain, and 587 with both symptoms referred for exercise echocardiography.ResultsCompared to those with chest pain alone, patients referred for dyspnea alone were older, predominately men, and had lower workload, lower ejection fraction (EF), more prior myocardial infarction (MI), and abnormal rest electrocardiograms. Patients with both symptoms were similar to those with dyspnea, but more had prior revascularization. Exercise echocardiography showed ischemia in 42% of patients with dyspnea, 19% with chest pain, and 58% with both symptoms. During 3.1 ± 1.8 years follow-up, cardiac death (5.2% vs. 0.9%, p < 0.0001) and nonfatal MI (4.7% vs. 2.0%, p < 0.0001) occurred more often in patients with dyspnea. Events in patients with both symptoms were similar to those with dyspnea, except for revascularization (20% vs. 13%, p = 0.0004). For patients with dyspnea, independent predictors of events were previous MI (hazard ratio [HR] 3.35, p < 0.0001), male gender (HR 1.94, p = 0.0252), EF (HR 0.95/10% increment, p < 0.0001), and increase in wall motion score index with exercise (HR 4.19/0.25 U, p < 0.0001), but not chest pain.ConclusionsPatients with unexplained dyspnea have a high likelihood of ischemia and an increased incidence of cardiac events. Exercise echocardiography provides independent information for identifying patients at risk. In patients with known or suspected coronary artery disease, dyspnea is a symptom requiring investigation

Risk factors associated with driving after cannabis use among Canadian young adults

This study identifid the most prominent risk factors associated with driving after cannabis use (DACU). 1,126 Canadian drivers (17–35 years old) who have used cannabis in the past 12 months completed an online questionnaire about sociodemographic information, substance use habits, cannabis effect expectancies, driving behaviours and peers’ behaviours and attitudes concerning DACU. A hierarchical logistic regression allowed identifying variables that were associated with DACU. Income (CA$30,000–CA$69,000), weekly-to-daily cannabis use, higher level of cannabis-related problems, expectation that cannabis facilitates social interactions, drunk driving, belief that DACU is safe, general risky driving behaviours, having a few friends who had DACU and injunctive norms predicted past 12-month DACU. Older age, holding negative expectations concerning cannabis, driving aggressively and perceived accessibility of public transportation decreased the probability of DACU. With restricted resources, programmes will be more efficient by targeting Canadian young adults most inclined to DACU by focussing on these risk factors

Spectroscopic confirmation of UV-bright white dwarfs from the Sandage Two-Color Survey of the Galactic Plane

We present spectroscopic observations confirming the identification of hot white dwarfs among UV-bright sources from the Sandage Two-color Survey of the Galactic plane and listed in the Lanning (Lan) catalog of such sources. A subsample of 213 UV bright Lan sources have been identified as candidate white dwarfs based on the detection of a significant proper motion. Spectroscopic observations of 46 candidates with the KPNO 2.1m telescope confirm 30 sources to be hydrogen white dwarfs with subtypes in the DA1-DA6 range, and with one of the stars (Lan 161) having an unresolved M dwarf as a companion. Five more sources are confirmed to be helium white dwarfs, with subtypes from DB3 to DB6. One source (Lan 364) is identified as a DZ 3 white dwarf, with strong lines of calcium. Three more stars are found to have featureless spectra (to within detection limits), and are thus classified as DC white dwarfs. In addition, three sources are found to be hot subdwarfs: Lan 20 and Lan 480 are classified as sdOB, and Lan 432 is classified sdB. The remaining four objects are found to be field F star interlopers. Physical parameters of the DA and DB white dwarfs are derived from model fits.Comment: To appear in the Astronomical Journa

Left atrial decompression through unidirectional left-to-right interatrial shunt for the treatment of left heart failure : first-inman experience with the V-Wave device

Aims: Elevated filling pressures of the left atrium (LA) are associated with poorer outcomes in patients with chronic heart failure. The V-Wave is a new percutaneously implanted device intended to decrease the LA pressure by the shunting of blood from the LA to the right atrium. This report describes the first-in-man experience with the V-Wave device. Methods and results: A 70-year-old man with a history of heart failure of ischaemic origin, left ventricular dysfunction (LVEF: 35%, pulmonary wedge: 19 mmHg), no right heart dysfunction, NYHA Class III and orthopnoea despite optimal treatment, was accepted for V-Wave device implantation. The device consists of an ePTFE encapsulated nitinol frame that is implanted at the level of the interatrial septum and contains a trileaflet pericardium tissue valve sutured inside which allows a unidirectional LA to right atrium shunt. The procedure was performed through a transfemoral venous approach under fluoroscopic and TEE guidance. The device was successfully implanted and the patient was discharged 24 hours after the procedure with no complications. At three-month follow-up a left-to-right shunt through the device was confirmed by TEE. The patient was in NYHA Class II, without orthopnoea, the Kansas City Cardiomyopathy index was 77.6 (from 39.1 at baseline) and NT-proBNP was 322 ng/mL (from 502 ng/mL at baseline). The QP/QS was 1.17 and the pulmonary wedge was 8 mmHg, with no changes in pulmonary pressure or right ventricular function. Conclusions: Left atrial decompression through a unidirectional left-to-right interatrial shunt represents a new concept for the treatment of patients with left ventricular failure. The present report shows the feasibility of applying this new therapy with the successful and uneventful implantation of the V-Wave device, which was associated with significant improvement in functional, quality of life and haemodynamic parameters at 90 days

Usefulness of an accelerated transoesophageal stress echocardiography in the preoperative evaluation of high risk severely obese subjects awaiting bariatric surgery

<p>Abstract</p> <p>Background</p> <p>Severe obesity is associated with an increased risk of coronary artery disease (CAD). Bariatric surgery is an effective procedure for long term weight management as well as reduction of comorbidities. Preoperative evaluation of cardiac operative risk may often be necessary but unfortunately standard imaging techniques are often suboptimal in these subjects. The purpose of this study was to demonstrate the feasibility, safety and utility of transesophageal dobutamine stress echocardiography (TE-DSE) using an adapted accelerated dobutamine infusion protocol in severely obese subjects with comorbidities being evaluated for bariatric surgery for assessing the presence of myocardial ischemia.</p> <p>Methods</p> <p>Subjects with severe obesity [body mass index (BMI) >40 kg/m²] with known or suspected CAD and being evaluated for bariatric surgery were recruited.</p> <p>Results</p> <p>Twenty subjects (9M/11F), aged 50 ± 8 years (mean ± SD), weighing 141 ± 21 kg and with a BMI of 50 ± 5 kg/m²were enrolled in the study and underwent a TE-DSE. The accelerated dobutamine infusion protocol used was well tolerated. Eighteen (90%) subjects reached their target heart rate with a mean intubation time of 13 ± 4 minutes. Mean dobutamine dose was 31.5 ± 9.9 ug/kg/min while mean atropine dose was 0.5 ± 0.3 mg. TE-DSE was well tolerated by all subjects without complications including no significant arrhythmia, hypotension or reduction in blood arterial saturation. Two subjects had abnormal TE-DSE suggestive of myocardial ischemia. All patients underwent bariatric surgery with no documented cardiovascular complications.</p> <p>Conclusions</p> <p>TE-DSE using an accelerated infusion protocol is a safe and well tolerated imaging technique for the evaluation of suspected myocardial ischemia and cardiac operative risk in severely obese patients awaiting bariatric surgery. Moreover, the absence of myocardial ischemia on TE-DSE correlates well with a low operative risk of cardiac event.</p