Amount Of St Research Articles

Abstract 2600: Development of TCR-stimulating 300.19 and 300.19-hB7-1 cells using modified anti-CD3 scFv constructs

Abstract To facilitate immunological assays which require T cell activation, we made two membrane anchored anti-CD3 single chain fragment variable (scFv) constructs: one named Steinberger (St, which includes the hTIM-3 mucin domain as linker and medium strength human PGK promoter) and the other named Riley (Ri, which includes hCD8 stem as linker and weaker human UBC promoter). Isolating T cells activated using adherent CHO-TCR-Activator cells is labor intensive, results in variable amounts of CHO cells, and makes it difficult to examine early time points after TCR activation. To combat this issue, we established stable expressing cell lines by transfecting St and Ri into 300.19 cells (Abelson leukemia virus transformed murine pre-B cell line that grows as non-adherent single cells) as well as 300.19 cells stably transfected with hB7-1 and selected 300.19-hB7-1-St, 300.19-hB7-1-Ri, 300.19-St, and 300.19-Ri using the following procedures. We electroporated 300.19 and 300.19-hB7-1 cells with three different amounts of St and Ri linearized plasmid: 0.5µg, 5µg, and 50µg. After selection for resistant cells with hygromycin and puromycin, we stained each cell line with goat anti-mouse IgG (Fab2-specific)-Alexa647 and sorted into three levels of scFv expression (high, medium, and low) and cultured single cell clones. We tested the T cell-stimulatory capacities of our anti-CD3 cells in a Jurkat T cell model through assay of increased IL-2 promoter mediated transcription of luciferase compared to control and ranked the stimulatory capacity of each clone. We found that T cell ligation by 300-hB7-1-Ri and 300-hB7-1-St cells induced the highest IL-2 promoter luciferase reporter activity while the 300-Ri and 300-St induced significant but lesser amounts. Surprisingly, Ri construct cells were generally stronger than the St clones though the literature says the PGK promoter (St plasmid) is stronger than the UBC promoter (Ri plasmid). This difference in stimulatory capacity may be due to the Ri construct (scFv-CD8 linker) being more stable than the St construct (scFv-hTIM3 linker) or to different promoter activity in mouse pre-B cells. Our results also suggest that the amount of DNA transfected may be predictive of construct expression level. The TCR-engaging capacity of our cell lines makes them a widely applicable tool in cancer immunotherapy research. These cells improve the TCR-engaging assay technique by avoiding the use of adherent CHO-TCR-Activator cells and/or CD28 antibodies. Collectively, our anti-CD3 scFv construct-expressing cells may enable researchers to better understand the cascading processes involved in T cell proliferation and differentiation into effector T cells, assess the dynamics of co-stimulatory and co-inhibitory receptors under various controlled levels of T cell stimulation, and understand tumor microenvironments and cytokine production with and without CD28 co-stimulation. Citation Format: Melissa T. Bu, Baogong Zhu, Gordon J. Freeman. Development of TCR-stimulating 300.19 and 300.19-hB7-1 cells using modified anti-CD3 scFv constructs [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2600.

Patterns of accelerometer-derived sedentary time across the lifespan

ABSTRACTWe aimed to describe ST and its patterns on a national level. A hip-worn accelerometer (ActiGraph GT1M) was used to collect data during waking hours from 4575 Portuguese’ participants from 2007–2009 (2683 females) aged 10–102 years old. Data was presented by sex, in 5-years age intervals, and by adolescents (n=2833), adults (n=1122), and older adults (n=620). Lambda-mu-sigma (LMS) smoothed percentile curves were estimated. Girls, women, and older women spent 61, 57, and 64% of wear time in ST, respectively. In males, ST represented 57, 60, and 62% of wear time respectively for boys, men, and older men. Comparing to other age groups, older adults spent a larger amount of ST in bouts ≥30-min (women: 33%, men: 39% of total ST). The number of breaks/ST hour were: 10.6 in girls, 11.7 in women, and 9.6 in older women. In males, the number of breaks/ST hour were: 11.2, 10.5, and 8.5 for boys, men, and older men. In conclusion, ST was not consistently higher at older ages. Instead, we found that the potential critical moments in which ST may be higher are during adolescence and in the transition from adulthood into older adulthood, which represents critical periods for interventions.

Preparation of Avermectin/Grafted CMC Nanoparticles and Their Sustained Release Performance

Avermectin (AVM) is a highly efficient pesticide against a variety of insects and is widely used in agriculture. However, it is susceptible to oxidation and photolysis, resulting in instability under UV irradiation and a short half-life. Herein, sodium carboxymethyl cellulose (CMC) was grafted by styrene (St), Methyl methacrylate (MMA) and butyl acrylate (BA) respectively to prepare grafted polymer nanoparticles in application for AVM sustained released. And the influence of different grafted monomer and the grafted rate on the AVM/grafted polymer nanoparticles performance was discussed. The larger the grafted rate of St was, the larger the particle size of AVM/grafted polymer nanoparticles had with a higher drug loading rate and stronger resistance to ultraviolet light. Besides, the particle size, drug loading rate and the ability of anti-ultraviolet light of grafted CMC emulsion was also influenced by the modifying agent. While the concentration of AVM was kept the same, the acrylic esters (MMA and BA) grafted emulsion have smaller particle sizes with higher drug loading rates and stronger anti-ultraviolet ability comparing to styrene (St) grafted emulsion. The effect of different amount of St and different monomer grafted on the sustained release performance of AVM/grafted polymer was also investigated. As the grafted rate of St increased, the release rate became smaller. The release speed has a sequence of CMC-g-PBA > CMC-g-PS > CMC-g-PMMA when CMC grafted with different monomer. Their sustained release curves can be described by Korsmeyer-Peppas equation. Finally, the insect toxicity test showed that insecticide toxicity against diamondback moth (Plutella xylostella L.) has no apparent difference among the AVM and AVM/grafted polymer nanoparticles indicating that AVM/grafted polymer nanoparticles can reduce the amount of organic solution used for dissolution and prolonged its service life without decreasing its insecticide toxicity.

The g-C<sub>3</sub>N<sub>4</sub> Nanosheets Separated by PS for Photocatalytic Degradation of Dye

Polymerization of styrene (St) stabilized by graphitic carbon nitride (g-C3N4) nanosheets, containing hydrophobic conjugated structure and hydrophilic oxygen-containing functional groups, is conducted at varying styrene concentration. It is found that the morphology of polystyrene (PS)/g-C3N4 nanocomposites tends to transform from g-C3N4 nanosheets coated PS nanospheres to g-C3N4 nanosheets separated by PS with irregular morphology by further increasing the concentration of St. The strong interaction between PS and g-C3N4 nanosheets, suggesting by FT-IR, XRD patterns and UV–vis spectra results, and the amount of St are responsible for the structure and morphology of the final product. The g-C3N4 nanosheets separated by PS exhibit the highest photocatalytic efficiencies towards degradation of methylene blue (MB), due to the specific structure and morphology. The PS separates g-C3N4 nanosheets, obstructs the aggregates of g-C3N4 nanosheets. On the other hand, the PS as a collector gathers the MB, which is benefit for the close contact between g-C3N4 nanosheets and MB, achieving the collective effect to greatly increase the photocatalytic efficiency.

Influences of Bis-(2,6-Diisopropylphenyl) Carbodiimide on the Thermal Stability and Crystallization of Poly(P-Dioxanone)

ABSTRACTThe influences on the thermal degradation and crystallization behaviors of poly(p-dioxanone) (PPDO) were initially investigated by adding bis-(2,6-diisopropylphenyl) carbodiimide (labeled as St). It was found that the addition of St could significantly enhance the thermal stability and crystallizability of PPDO. The thermal decomposition temperature of PPDO increased with the increase of the amount of St added. The thermal decomposition activation energies of PPDO increased from 94.2 to 130.8 kJ mol−1 in the case of 5 wt% St. The addition of St did not change the crystal structure of PPDO, while it increased the number of nucleation sites and improved the crystallizability of PPDO. The crystallization activation energies, calculated by the Kissinger method, for PPDO and PPDO/5 wt% St were −111.4 and −141.5 kJ mol−1, respectively, confirming the crystallizability of PPDO was enhanced after the addition of St.

Swelling Behavior of Guar Gum-g-Poly(Sodium Acrylate -co-Styrene)/Attapulgite Superabsorbent Composites

A series of superabsorbent composites, guar gum-g-poly(sodium acrylate-co- styrene)/attapulgite [GG-g-P(NaA-co-St)/APT], were prepared by simultaneous grafting partially neutralized acrylic acid and hydrophobic styrene (St) onto guar gum in the presence of attapulgite as an inorganic component. Equilibrium swelling capacity strongly depended on the concentration of St, drastically increasing with increasing St concentration to 24.3 mmol/L and then decreasing. The influence of St concentration on the swelling kinetics of the superabsorbent was studied by means of a Schott's second-order model. The proper amount of St is of benefit for the improvement of the initial swelling rate in either distilled water or saline solution. The influence of St concentration on the swelling behaviors in various external media (the aqueous solutions of various salts, pHs, hydrophilic organic solvent/water mixture and surfactants) was also investigated systematically. Results showed that the concentration of St is the key factor influencing equilibrium swelling capacity of the superabsorbent composites in each swelling media, and moderate amounts of St could enhance the responsiveness of the corresponding superabsorbent composite to external stimulation.

Monodisperse ultrafine polystyrene nanoparticles prepared by a semicontinuous microemulsion polymerization

Monodisperse ultrafine polystyrene nanoparticles have been successfully prepared under low levels of surfactant through a novel semicontinuous microemulsion polymerization, in which the first part of monomer (Sti) is added dropwise while the subsequent supply to the polymerizing system is delivered in one potion. Polystyrene nanoparticles with number-average diameter of 17.4 nm and polydispersity index of 1.06 were obtained using low level of surfactant/monomer weight ratio of 0.20. Influencing of parameters including amount of St 1 , solid content, initiator, reaction temperature, and cosurfactant on the resultant particle size and size distribution were investigated. The mechanism of nucleation and particle growth was discussed as well.

Reply to comment by N. D. Marsh and H. Svensmark on “Solar influences on cosmic rays and cloud formation: A reassessment”

[1] Svensmark and Friis-Christensen [1997] (hereinafter referred to as SFC97) proposed a ‘‘galactic cosmic ray (GCR), clouds, and climate’’ hypothesis that cosmic ray flux, modulated by solar activity, may modify global total cloud cover (TCC) and thus global surface temperature by changing the number of ions in the atmosphere and thus the cloud droplet formation. This GCR-TCC hypothesis has been questioned by many authors who examined correlations of GCR with various satellite cloud properties and over different time intervals. We note that the SFC97 hypothesis differs from the one proposed by Marsh and Svensmark [2000] (hereinafter referred to as MS00), who postulated that the GCR influence on cloudiness is restricted to low cloud cover (LCC). [2] All the articles in this debate were based on satellite data and limited to the ocean. By contrast, Sun and Bradley [2002] (hereinafter SB02) combined short-period satellite data (from the International Satellite Cloud Climatology Project, ISCCP) with long-term visual total cloud observations to reassess the GCR-TCC relationship over the ocean and the land as well. The SB02 study was initialized in early 2000, focusing on the GCR-TCC hypothesis. In the early spring of 2001 we added to our revision several comments regarding the GCR-LCC hypothesis. We concluded in our analysis that there is no solid evidence for the existence of a GCR-cloud correlation (either total cloud or low cloud cover). [3] Marsh and Svensmark [2004] (hereinafter referred to as MS04) raised five comments about our analysis and finally claimed that ‘‘On the basis of satellite observations, there continue to be strong indications of a globally distributed correlation between cosmic rays and low-cloud cover.’’ We will demonstrate in this reply that their comments are either unfounded or illogical. All of their comments are dealt with in section 2, but issues relevant to the GCR-LCC hypothesis will be separately addressed in section 3. New evidence will be present in section 3 to indicate that the quality of the ISCCP infrared (IR) LCC data set, which MS00 and Marsh and Svensmark [2003] (hereinafter referred to as MS03) used to create the GCR-LCC hypothesis, is highly questionable. This reply confirms the view we expressed on the work of SB02 that there is no solid GCR-cloud relationship.

Nitroxide-controlled free radical copolymerization of styrene and acrylonitrile monitored by electron spin resonance and fourier transform infrared technique in situ

Nitroxide-mediated homopolymerization of styrene (St) and copolymerization of styrene and acrylonitrile (An) were monitored respectively by electron spin resonance and Fourier transform infrared technique in situ, and the polymerization kinetics was investigated in detail. Homopolymerization of St was well controlled in the presence of 4-hydroxyl-2,2,6,6-tetramethyl-l-piperidinyloxy (HTEMPO, N*) at high temperature. The initiation reactions and polymerization rates were changed by varying initiators, such as benzoyl peroxide (BPO), 2,2-azobis-isobutylonitrile (AIBN) and dicyclohexyl dicarbonate peroxide (DCPO) because of the different half-period values of the initiators. For the St system containing the DCPO with longer half-period value, the reaction rate was enhanced and the final conversion was increased because the larger amount of the DCPO residual released continuously the excess radicals to increase growing radical concentration. But the polydispersity of the resulting polymer became somewhat larger. The copolymerization of St and An with AIBN as initiator in the presence of HTEMPO was also tamed in the living fashion of stable free radical polymerization in the range of the total monomer conversion below 40%. The hydrogen-abstracting effect on the penultimate unit of the primary radicals or growing radical was observed through a copolymerization process. The larger amount of St was combined into the copolymers, leading to an increase of the An contents especially in the latter period of copolymerization, due to the inhibited addition of An on the growing radicals with end An unit. The normal random copolymerization was interrupted, resulting in the different virtual reactivity ratio. The dissociation and combination equilibrium between N* and the different end St and An units on propagating radicals affected the consuming rates of St and An. A possible copolymerization mechanism containing hydrogen-abstracting reaction was suggested.

Clinical, electrocardiographic, and biochemical data for immediate risk stratification in acute coronary syndromes.

The recent evolution in therapeutic options for acute coronary syndromes (ACS) mandates early risk stratification in order to select the appropriate treatment strategy for individual patients. Simple clinical data derived from the patient's medical history and physical examination, a standard twelve-lead electrocardiogram (ECG), and determinations of biochemical markers of myocardial damage can be obtained in the emergency room and serve as a guide for deciding appropriate medical management and optimal use of available resources. Even the most important classification of the ACS is based upon a simple and dichotomous description of the ECG, where the presence of ST-segment elevation mandates an immediate attempt to restore coronary perfusion (either pharmacologically or mechanically), whereas its absence suggests pharmacological stabilization before further evaluation. Across the whole spectrum of ACS, clinical history data (such as older age, previous coronary events, and diabetes) and clinical variables (such as higher heart rate, lower blood pressure, and higher Killip class) are the most powerful prognostic determinants at multivariate analyses derived from large databases. The ECG adds significant and independent prognostic information using the analysis of qualitative (direction of ST-segment shift, associated T-wave inversion, and presence of conduction disturbances) and quantitative (number of leads involved, amount of ST- segment shifts, duration of QRS) characteristics. Biochemical markers of myocardial damage have also been identified as independent predictors of events. In addition, retrospective analyses of clinical trials have suggested that biochemical markers might serve as a guide to select pharmacological therapy. However, how to best combine electrocardiographic and biochemical data for immediate risk stratification remains to be further elucidated.