Laval University

About: Laval University is a education organization based out in Québec, Quebec, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 31177 authors who have published 69549 publications receiving 2435031 citations.

Crystal-induced neutrophil activation. IV. Specific inhibition of tyrosine phosphorylation by colchicine.

Abstract: We recently demonstrated that pathologically relevant inflammatory microcrystals, namely triclinic monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals, potently stimulate a characteristic protein tyrosine phosphorylation pattern in human neutrophils that differed from that observed in response to other soluble or particulate agonists. In this study, the effects of colchicine on protein tyrosine phosphorylation induced by MSU and CPPD crystals in human blood neutrophils were investigated. Immunoblot analysis with antiphosphotyrosine antibodies demonstrated that colchicine dose-dependently inhibited the tyrosine phosphorylation of all the proteins phosphorylated in response to MSU and CPPD crystals. Other microtubule-disruptive agents such as vinblastine, nocodazole, and colcemid also inhibited crystal-induced protein tyrosine phosphorylation while lumicolchicine and trimethylcolchicinic acid were without effect. Indomethacin and phenylbutazone were similarly without effect on microcrystal-induced tyrosine phosphorylation. Colchicine, as well as the other active alkaloids, failed to inhibit the protein tyrosine phosphorylation elicited by FMLP, C5a, leukotriene B4, and unopsonized zymosan. Overall, these results demonstrate that colchicine specifically and significantly inhibits the protein tyrosine phosphorylation induced by MSU and CPPD crystals and suggest that its effects are associated, at least in part, with its interaction with microtubules. Furthermore, the use of microtubule-disrupting drugs demonstrate that the mechanisms implicated in the induction of protein tyrosine phosphorylation by microcrystals differed from those involved in response to other soluble or particulate agonists.

Evaluation of Filters for the Sampling and Quantification of RNA Phage Aerosols

Abstract: This study exploits the virulent bacteriophages phi 6 (dsRNA) and MS2 (ssRNA) as surrogates for airborne RNA viruses. Two different filter types, polytetrafluoroethylene (PTFE) and polycarbonate (PC), were tested for their efficiency in collecting aerosolized RNA phages. Two commercial kits were tested for total RNA isolation. Also, heat shock treatments were performed in three different media to obtain the most favorable conditions for reverse transcription assays of dsRNA. Our findings suggest that PC filters are more suitable to recover infectious airborne RNA viruses as determined by plaque assays. Both types of filters were equally efficient in recovering RNA from aerosolized phage phi 6 as established by qRT-PCR. Viral samples should be treated with QIAamp Viral RNA Mini Kit and a 5 min heat shock treatment at 110°C in TE buffer before RT-PCR to maximize detection of phage phi 6. Overall, the infectivity of the recovered phages was severely affected by the aerosolization/air sampling process and the...

Proteolysis of poly(ADP-ribose) polymerase by caspase 3: Kinetics of cleavage of mono(ADP-ribosyl)ated and DNA-bound substrates

Abstract: Poly(ADP-ribose) polymerase (PARP) is an abundant nuclear enzyme which is responsible for synthesis of poly(ADP-ribose) in response to DNA damage caused by numerous agents and during DNA base excision repair. After DNA damage, the enzyme binds to nicks in DNA through its N-terminal zinc fingers and catalyzes the formation of poly(ADP-ribose) on various nuclear acceptors including itself. When DNA damage is extensive, cells induce their own demise by activating the proteases that induce apoptosis (caspases) which cleave PARP and other death substrates. Here we report the development of a new approach to investigate the sensitivity of mono(ADP-ribosyl)ated and DNA-bound PARP to cleavage during apoptosis. The development of a stoichiometric labeling procedure of the enzyme has allowed us to evaluate the catalytic properties of caspase 3 toward mono(ADP-ribosyl)ated PARP at various enzyme:substrate molar ratios. We show that low levels of automodification (< or = 3 U of ADP-ribose per chain) do not inhibit the proteolysis of the substrate. In addition, we demonstrate that binding of unmodified PARP to DNA influences the kinetics of its cleavage by caspase 3.

A new architecture of planar three-degree-of-freedom parallel manipulator

Abstract: In this paper a new architecture of a planar three-degree-of-freedom (3-dof) parallel manipulator is presented. In the proposed mechanism, the prismatic actuators are fixed to the base which leads to a reduction of the inertia of the moving links and hence makes it attractive, particularly when high speeds are required and electric actuation is considered. After introducing the mechanism, a kinematic analysis is reported. Then, velocity and acceleration equations are derived. Based on the geometry of the manipulator a workspace analysis is performed and a description of the boundaries of the workspace is provided. This manipulator can be used in robotic applications involving the positioning and orientation of a rigid body on the plane with high stiffness or accuracy. Additionally, the mechanism can find applications in motion simulators or other high-precision or high-speed devices.

Effects of Pharmacologic and Nonpharmacologic Interventions on Insomnia Symptoms and Self-reported Sleep Quality in Women With Hot Flashes: A Pooled Analysis of Individual Participant Data From Four MsFLASH Trials

Abstract: Study Objectives The Menopause Strategies: Finding Lasting Answers for Symptoms and Health network conducted three randomized clinical trials (RCTs) testing six interventions treating vasomotor symptoms (VMS), and also collected self-reported sleep outcomes. A fourth RCT assessed an intervention for insomnia symptoms among women with VMS. We describe these seven interventions’ effects relative to control in women with comparably severe insomnia symptoms and VMS.