Effect of a structurally modified human granulocyte colony stimulating factor, G-CSFa, on leukopenia in mice and monkeys

<p>Abstract</p> <p>Background</p> <p>Granulocyte colony stimulating factor (G-CSF) regulates survival, proliferation, and differentiation of neutrophilic granulocyte precursors, Recombinant G-CSF has been used for the treatment of congenital and therapy-induced neutropenia and stem cell mobilization. Due to its intrinsic instability, recombinant G-CSF needs to be excessively and/or frequently administered to patients in order to maintain a plasma concentration high enough to achieve therapeutic effects. Therefore, there is a need for the development of G-CSF derivatives that are more stable and active in vivo.</p> <p>Methods</p> <p>Using site-direct mutagenesis and recombinant DNA technology, a structurally modified derivative of human G-CSF termed G-CSFa was obtained. G-CSFa contains alanine 17 (instead of cysteine 17 as in wild-type G-CSF) as well as four additional amino acids including methionine, arginine, glycine, and serine at the amino-terminus. Purified recombinant G-CSFa was tested for its in vitro activity using cell-based assays and in vivo activity using both murine and primate animal models.</p> <p>Results</p> <p>In vitro studies demonstrated that G-CSFa, expressed in and purified from <it>E. coli</it>, induced a much higher proliferation rate than that of wild-type G-CSF at the same concentrations. In vivo studies showed that G-CSFa significantly increased the number of peripheral blood leukocytes in cesium-137 irradiated mice or monkeys with neutropenia after administration of clyclophosphamide. In addition, G-CSFa increased neutrophil counts to a higher level in monkeys with a concomitant slower declining rate than that of G-CSF, indicating a longer half-life of G-CSFa. Bone marrow smear analysis also confirmed that G-CSFa was more potent than G-CSF in the induction of granulopoiesis in bone marrows of myelo-suppressed monkeys.</p> <p>Conclusion</p> <p>G-CSFa, a structurally modified form of G-CSF, is more potent in stimulating proliferation and differentiation of myeloid cells of the granulocytic lineage than the wild-type counterpart both in vitro and in vivo. G-CSFa can be explored for the development of a new generation of recombinant therapeutic drug for leukopenia.</p

Neuroprotective Effects of Ischemic Preconditioning on Global Brain Ischemia through Up-Regulation of Acid-Sensing Ion Channel 2a

Transient forebrain or global ischemia induces cell death in vulnerable CA1 pyramidal neurons. A brief period of ischemia, i.e., ischemic preconditioning, affords CA1 neurons robust protection against a subsequent, more prolonged ischemic challenge. Using the four-vessel occlusion model, we established an ischemic preconditioning model in which rodents were subjected to 3 min of sublethal ischemia 48 h before a 15 min lethal ischemia. We showed that preconditioning attenuated the ischemia-induced neural cell death and DNA fragmentation in the hippocampal CA1 region. RT-PCR and western blot analysis showed that preconditioning prior to an ischemic insult significantly increased ASIC 2a mRNA and protein expression in comparison to the ischemic insult alone (p < 0.01). These findings implicate a new role of ASIC 2a on endogenous neuroprotection from ischemic insult

Over-expression of a gamma-tocopherol methyltransferase gene in vitamin E pathway confers PEG-simulated drought tolerance in alfalfa

α-Tocopherol is one of the most important vitamin E components present in plant. α-Tocopherol is a potent antioxidant, which can deactivate photoproduced reactive oxygen species (ROS) and prevent lipids from oxidation when plants suffer drought stress. γ-Tocopherol methyltransferase (γ-TMT) catalyzes the formation of α-tocopherol in the tocopherol biosynthetic pathway. Our previous studies showed that over-expression of γ-TMT gene can increase the accumulation of α-tocopherol in alfalfa (Medicago sativa). However, whether these transgenic plants confer increased drought tolerance and the underlying mechanism are still unknown.This work was financially supported by Earmarked Fund for China Agriculture Research System (CARS-34), the National Natural Science Foundation of China (31872410), National Crop Germplasm Resources Center (NICGR-78), and the Agricultural Science and Technology Innovation Program (ASTIPIAS10)

Dynamic mode decomposition and reconstruction of the transient propeller wake under a light loading condition

This research aims to extend our understanding of propeller wake dynamics under a light loading condition, thereby laying a foundation for design optimization and flow control of the propeller. Dynamic mode decom-position (DMD) and reconstruction are used to analyze the transient vortical wake structures obtained by large eddy simulation. The propeller wake includes stable tip and hub vortices without interacting evolution at the light loading condition, and elliptical instabilities are observed downstream of the tip vortices. DMD describes the most energetic modes and the corresponding dominant frequencies are the blade passing frequency and its multiples. The coherent structures identified via DMD are primarily associated with the ordered convection of the tip vortices and have little correlation with the hub vortices. Additionally, the propeller wake flow is reconstructed using the first four DMD modes, and the primary wake features are well restored with a maximum reconstructed error of 7.98%. This demonstrates that the flow-field reconstruction based on the DMD reduced-order model is promising for predicting the propeller wake and controlling the propeller operation

Numerical investigations into the ventilation elimination mechanism of a surface-piercing hydrofoil

This paper investigates the ventilation elimination mechanisms during the deceleration process of a surfacepiercing hydrofoil using the unsteady Reynolds-averaged Navier-Stokes (RANS) method together with a Volume of Fluid (VOF) model. The numerical results are in good agreement with the experimental data. The ventilation elimination mechanism of the surface-piercing hydrofoil is analyzed from the perspectives of the hydrofoil hydrodynamic performance, the ventilated cavity evolution, vortex structures, and re-entrant jets. The results indicate that the ventilation elimination includes three stages, i.e. a decrease in the ventilated cavity, washout, and reattachment. The decrease in the ventilated cavity is due to the hydrofoil speed decrease in the FV flow. Washout is the transition from fully ventilated to partially ventilated flow, and reattachment is the transition from partially ventilated to fully wetted flow. The underwater vortex structures around the surfacepiercing hydrofoil are composed of a tip vortex, an unstable vortex induced by the shear layer, and a Karman vortex caused by the vortex shedding from the trailing edge of the hydrofoil. Ventilation stability strongly depends on the re-entrant jet. When Phi (the angle between the flow direction and the closure line of the ventilated cavity) is greater than 45 degrees, the re-entrant jet impinges on the ventilated cavity's leading edge and destabilizes the ventilated cavity

LES investigation into the cavity shedding dynamics and cavitation-vortex interaction around a surface-piercing hydrofoil

Recent experiments have found that there is unstable vaporous cavitation around a surface-piercing hydrofoil at high Froude numbers and small yaw angles, and it would promote ventilation formation [R. Huang et al., "Investigations into the ventilated cavities around a surface-piercing hydrofoil at high Froude numbers, " Phys. Fluids 34, 043304 (2022)], but the cavity shedding dynamics and the mechanism of cavitation-vortex interaction are still open problems. In this paper, the unstable vaporous cavities around a surface-piercing hydrofoil are numerically investigated using the large-eddy simulation coupled with the Schnerr-Sauer cavitation model. Numerical simulations can predict the cavity features, including an aerated base cavity aft of the hydrofoil trailing edge, vaporous cavitation at the hydrofoil suction surface, and tip-vortex cavitation. A U-shaped vapor cloud shedding together with a horseshoe vortex is observed during the unsteady cavitation evolution, that is, the cavity development, cutoff, and collapse. This irregular shedding is related to the three-dimensional reentrant jet induced by the velocity reflection at the vaporous cavity closure line. Furthermore, the effects of the vaporous cavitation on the vorticity generation are attributed to vortex stretching, baroclinic torque, and vortex dilatation by using the vorticity transport equation. This study could contribute to the novel hydrofoil designs and their flow control. Published under an exclusive license by AIP Publishing

Numerical investigations into supercavitating flows and hydrodynamic characteristics of a heaving hydrofoil

This paper presents the effects of heaving motions on the hydrodynamic characteristics, supercavitating flow regimes and vortex structures for a two-dimensional (2D) supercavitating hydrofoil. The sinusoidal heaving motion of the supercavitating hydrofoil is realized by overset grid technology. The lift coefficient, drag coefficient, supercavitating flow regime and vortex structures around the supercavitating hydrofoil are analyzed and compared among different amplitudes of the heaving motion. The predicted cavities and the hydrodynamic characteristics are in good accordance with the experiments at a stationary state. The lift coefficient and drag coefficient of the heaving hydrofoil present a sinusoidal law, which is related to the effective angle of attack. The heaving motion would affect the cavity length and its thickness. The greater the heaving amplitude, the greater the difference in cavity pattern at different heaving positions. The cavity variation would affect the shear layer and thus change the vortex shedding characteristics, which are different from those at a stationary state

Overexpression of alfalfa γ-tocopherol methyltransferase (γ-TMT) gene increases salt susceptibility of transgenic Arabidopsis in seed germination

As antioxidants, tocopherols deactivate reactive oxygen species and prevent lipids from oxidation in response to abiotic stresses. γ-Tocopherol methyltransferase (γ-TMT) catalyzes the conversion of γ-tocopherol into α-tocopherol which has the highest biological activity. To investigate roles of γ-TMT in seed germination under salinity stress, we heterologously overexpressed an alfalfa MsTMT gene in Arabidopsis. MsTMT transgenic seeds germinated much slower than that of Arabidopsis wild-type (WT) seeds under salt stress or exogenous abscisic acid (ABA) treatment, indicating enhanced osmotic and ABA sensitivity in transgenic seeds. Under salinity stress, expression levels of ABA biosynthesis genes (NCED4 and NCED9) and signaling genes (ABI3 and ABI5) were increased in transgenic seeds. Meanwhile, the expression of GA biosynthesis genes (GA3OX1 and GA3OX2) were repressed and that of GA signal suppressor genes RGL2 was enhanced. Moreover, overexpression of MsTMT promoted the release of seemucilage and contributed to the redistribution of pectins. Interestingly, removal of seed mucilage eliminated the difference in the initiation of seed germination between WT and transgenic lines. Taken together, MsTMT had a strong influence on the response to salinity stress in transgenic Arabidopsis during seed germination. Our results reveal a novel role of MsTMT in mediating the regulations of ABA and GA signaling in seed germination, which is also associated with mucilage release and structure. This study provides new insights into the regulatory network controlled by tocopherol biosynthesis gene in response to abiotic stress in plants.This work was supported by the grant from the Earmarked Fund for China Agriculture Research System (CARS-34), National Nature Science Foundation of China (31872410), and the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences (ASTIP-IAS10)

Rational molecular design for isoindigo-based polymer semiconductors with high ductility and high electrical performance

Achieving good electrical properties and ductility of polymer semiconductors has always been challenging. In this work, a series of isoindigo derivative-based conjugated polymers was studied in an effort to gain a better understanding of the influence of polymer main and side chain structures on their electrical and mechanical properties. The results suggested that the introduction of alkyl side chains onto the donors can significantly enhance the mechanical properties of isoindigo-based polymers; however, the electrical properties of the films greatly deteriorated due to the large steric hindrance by the chain. The insertion of strong electron-withdrawing units, such as benzodifurandione, into the isoindigo chain during the synthesis of a bis(2-oxoindolin-3-ylidene)-benzodifuran-dione (BIBDF)-based polymer (PBIBDF-BT) significantly boosted the electrical properties of the films without decreasing their mechanical properties. The crack onset in PBIBDF-BT thin films was observed at 50% tensile strain. In addition, PBIBDF-BT thin films exhibited bipolar transport properties with both electron and hole mobilities greater than 0.1 cm(2) V-1 s(-1) at 100% strain. It is found that the improvement of PBIBDF-BT performance is attributed to its proper molecular structure. The long alkyl side chains significantly increase the ductility of PBIBDF-BT thin films, and the strong electron-withdrawing BIBDF unit in the main chains enhances the local aggregation, resulting in a significant increase in mobility. These results indicate that the mechanical and electrical properties of conjugated polymers could simultaneously be improved through reasonable molecular design.11Nsciescopu