SimWorx: An ADA Distributed Simulation Application Framework Supporting HLA and DIS

This research consisted of the analysis, design, and implementation of a reusable application framework for distributed simulation which is compliant with both the DoD High Level Architecture (HLA) for Modeling and Simulation and the Distributed Interactive Simulation (DIS) standards. The goal was to create an Ada-based system for experimentation in distributed simulation. A subsidiary goal was to integrate the system with an existing Air Force Institute of Technology (AFIT) application framework for virtual simulations, Easy_Sim. The application framework was designed using object oriented techniques to enable experimenters to customize it via inheritance extension. The application framework, named SimWorx, consists of two sections: an HLA Federate skeleton, and a surrogate HLA Run Time Infrastructure (RTI) which has an HLA \u27front end and a DIS \u27back end\u27 to provide DIS compatibility. The SimWorx framework was successfully integrated with Easy_Sim to provide an Ada based joint simulation system for distributed virtual simulations

A new two-strip TLC method for the quality control of technetium-99m mercaptoacetyl-triglycine (^99mTc-MAG3).

<sup>99m</sup> Tc-mercaptoacetyl-triglycine ( <sup>99m</sup> Tc-MAG3) has been used for dynamic renal imaging since about 30 years. Free pertechnetate ( <sup>99m</sup> TcO <sub>4</sub> ), colloidal <sup>99m</sup> Tc (( <sup>99m</sup> TcO <sub>2</sub> ) <sub>n</sub> ), <sup>99m</sup> Tc-tartrate (precursor), precomplexes ( <sup>99m</sup> Tc-(MAG3) <sub>x</sub> ) and lipophilic <sup>99m</sup> Tc-MAG2 are the main radiochemical impurities that may occur in the preparation. The total amount of these impurities has to be identified before release of the product for patient administration to guarantee patient safety and good image quality. The European Pharmacopoeia suggests a method based on high-pressure liquid chromatography analysis in combination with a paper chromatography. This analytical method is time consuming, expensive and requires specially trained technicians. As a consequence, it is not widely applied in nuclear medicine radiopharmacies. We developed a simple method for radiochemical purity testing of <sup>99m</sup> Tc-MAG3. The method is based on thin layer chromatography with two strips to be developed in parallel. Method validation was carried out in comparison to the official methods of the companies and to the European Pharmacopoeia method. It was tested on specificity, accuracy, robustness and precision. The proposed method is able to identify and quantify the sum of all impurities occurring in the preparation, respecting the acceptance criteria for the radiochemical purity defined by the official methods. Hydrophilic and lipophilic compounds are identified separately and results are obtained within less than 20 minutes. Our method is simple, cost effective, fast and is suitable for employing dose calibrators or radiometric scanners

Purification and characterization of an oxidase activating factor of 63 kilodaltons from bovine neutrophils.

International audienceA 63-kDa protein, which behaves as an oxidase activating factor in bovine neutrophils, has been purified to electrophoretic homogeneity. The protein was isolated from the cytosol of resting bovine neutrophils after several steps, including ammonium sulfate precipitation and chromatography on AcA44, DE-52 cellulose, Mono Q, and Superose 12 in the presence of dithiothreitol. The oxidase activating potency of the protein was assayed with a cell-free system consisting of neutrophil membranes, GTP gamma S, arachidonic acid, and a complementary cytosolic fraction. The purification factor was 200 and the yield 3%. During the course of gel filtration on calibrated Superose 12, the 63-kDa protein eluted as a dimer. Its isoelectric point was 6.4 +/- 0.1. Antibodies raised in rabbits against the 63-kDa protein reacted with a protein of similar size in human neutrophils and in HL60 promyelocytic cells induced to differentiate into granulocytes. No immune reaction was observed in cytosol from undifferentiated HL60 cells, in extracts from bovine skeletal muscle, liver, and brain, or in cytosol prepared from neutrophils derived from a patient with an autosomal cytochrome b positive form of chronic granulomatous disease lacking the 67-kDa oxidase activating factor. Immunoblotting with the 63-kDa bovine protein antiserum demonstrated that activation of bovine neutrophil oxidase by phorbol myristate acetate induced the translocation of the 63-kDa protein from cytosol to the membrane

Activation of bovine neutrophil oxidase in a cell free system. GTP-dependent formation of a complex between a cytosolic factor and a membrane protein.

International audienceThe effect of guanine nucleotides on activation of the O2-. generating oxidase in a cell free system consisting of bovine neutrophils membranes, cytosol and arachidonic acid has been studied. In a complete system, GTP-gamma-S was stimulatory and GDP-beta-S inhibitory. When cytosol was omitted, both nucleotides acted as inhibitors. Activation parameters have been explored in a preincubation step prior to the oxidase assay. Stimulation was found to be maximal at 7 to 100 microM GTP-gamma-S. Whereas the time course of activation was monophasic when activation was performed at room temperature, it became biphasic at 2 degrees C, with a first plateau of activation attained after 1 min, followed by a slow rise lasting for more than 30 min. The following lines of evidence demonstrated that oxidase activation resulted from the formation of a complex between cytosolic factor(s) and a target protein in the plasma membrane. 1/ When activated membranes, in a suspension containing cytosol, arachidonic acid and GTP-gamma-S, were separated from soluble components by centrifugation and washed, their oxidase remained fully active. 2/ The activity of the washed membranes was lost upon addition of GDP-beta-S, urea and deoxycholate, but was preserved by addition of glutaraldehyde, a cross-linking reagent. The results of experiments in which cytosol and membrane fractions were incubated separately with GTP-gamma-S, suggested that GTP-gamma-S first interacts with a factor present in the cytosol, before reacting with a target protein in the plasma membrane

Cytosolic factors in bovine neutrophil oxidase activation. Partial purification and demonstration of translocation to a membrane fraction.

International audienceThe O2(.-)-generating oxidase of bovine neutrophils is activated in a cell-free system consisting of a particulate fraction enriched in plasma membrane and containing the dormant oxidase, a high-speed supernatant from neutrophil homogenate (cytosol), Mg ions, GTP gamma S, and arachidonic acid [Ligeti, E., Doussiere, J., & Vignais, P.V. (1988) Biochemistry 27, 193-200]. The cytosolic components participating in the activation of the membrane-bound oxidase have been investigated. These components were resolved into several active peaks by Q Sepharose chromatography. The oxidase-activating potency of these peaks was synergistically enhanced by combining samples from separate peaks, or by supplying them with a threshold amount of crude cytosol. Partial purification of two active fractions containing a limited number of proteins of 65, 56, 53, and 45 kDa was achieved by gel filtration of cytosol on Ultrogel AcA44, followed by chromatography on hydroxylapatite and Mono Q. The specific oxidase-activating potency of these partially purified fractions (activating potency per milligram of soluble protein) was 6-8-fold higher than that of crude cytosol; it was enhanced up to 75-fold by complementation with a minute amount of crude cytosol, which per se had a limited efficiency. These data indicate that oxidase activation requires more than one cytosolic component to be activated. To check whether translocation of cytosolic proteins to the membrane occurred concomitantly with oxidase activation, use was made of radiolabeled cytosolic proteins. Cytosol was treated with phenyl[14C]isothiocyanate ([14C]PITC), such that 60% of its activation potency was still present.(ABSTRACT TRUNCATED AT 250 WORDS

MAGNETIC EFFECTS OF TUNNELLING RECOMBINATION LUMINESCENCE IN CsI AND KCl DOPED CRYSTAL

Des cristaux de CsI et KCl dopés avec des impuretés monovalentes telles que Ag, Tl, Na, etc... et exposés à basse température à des radiations ionisantes présentent une luminescence qui persiste plusieurs heures après la fin de l'irradiation. Le processus est interprété comme une recombinaison due à un transfert d'énergie par effet tunnel entre électrons et trous piégés sur des sites voisins. L'application d'un champ magnétique extérieur (0 ⩽ B ⩽ 6T) induit dans CsI : NaI et KCl : AgCl (ou : NaCl) une forte diminution de l'intensité de la phosphorescence due à une polarisation partielle des spins électroniques des défauts. Aucun effet n'est observé dans CsI : TlI et KCl : TlCl (ou : CuCl). L'application d'un champ microonde résonant tend à compenser l'effet du champ magnétique et permet dans CsI : NaI seulement, la détection optique de la R. P. E. du centre du type trou self-trappé responsable du processus de phosphorescence.CsI and KCl crystals doped with monovalent impurities such as Ag, Tl, Na, etc... and exposed to ionising radiations at low temperature present a luminescence which persists many hours after the end of the irradiation. The process is attributed to a tunnelling recombination between nearby trapped electrons and holes. An external magnetic field (0 ⩽ B ⩽ 6T) induces in CsI : NaI and KCl : AgCl (or : NaCl) a strong reduction of the intensity of the phosphorescence caused by a partial polarization of the electron spins of the defect pairs. No effect has been found in CsI : TlI and KCl : TlCl (or : CuCl). The application of a resonant microwave field tends to compensate the magnetic field effect and allows in Csl : NaI only, the optical detection of EPR of the hole type defect responsible for the afterglow process

Parameters of activation of the membrane-bound O2- generating oxidase from bovine neutrophils in a cell-free system.

International audienceParameters governing the extent of activation of the O2- generating oxidase in a cell-free system derived from bovine neutrophils were examined. The reconstituted system consisted of the following: a particulate fraction enriched in plasma membrane and containing the oxidase, a soluble fraction containing cytosolic factor(s) required for oxidase a soluble fraction containing cytosolic factor(s) required for oxidase activation, a non hydrolyzable analog of GTP, and either arachidonic acid or sodium dodecyl sulfate. When the amount of arachidonic acid or sodium dodecyl sulfate was maintained at a fixed value with respect to the amount of membrane used, a sigmoidal response of oxidase activity to increasing amounts of cytosol added was observed. In contrast, when the concentration of arachidonic acid or sodium dodecyl sulfate was properly adjusted with respect to that of membrane and cytosol, the curve relating oxidase activity to cytosol was hyperbolic, pointing to a simple michaelian relationship for the dependence of oxidase activation on the activating factor(s) of cytosol. Another parameter affecting oxidase activation was the ionic strength of the reconstitution medium, the extent of activation being lower at high ionic strength