The assembly of infectious human immunodeficiency virus (HIV) requires that Gag transport and oligomerization be coordinated with its association with other viral proteins, viral RNAs, and cellular membranes. We have developed a replication-competent HIV type 1 molecular clone that carries a Gag-internal or interdomain green fluorescent protein (iGFP) fusion to reveal a physiologically accurate temporal sequence of Gag localization and oligomerization during the formation of infectious HIV. This recombinant HIV is as infectious as native HIV in single-round infectivity assays, validating its use for trafficking studies. It replicates robustly in permissive MT4 cells and is infectious, yet it spreads poorly in other T-cell lines. Immunofluorescence of Gag-iGFP showed a pattern very similar to that of native Gag. However, the intense plasma membrane Gag-iGFP fluorescence contrasts markedly with its immunofluorescence at this site, indicating that many Gag epitopes can be masked by oligomerization. Consistent with this, fluorescence resonance energy transfer studies visualized intense Gag oligomerization at the plasma membrane and weaker oligomerization at cytoplasmic sites. Four-dimensional, time-lapse confocal imaging reveals a temporal progression of Gag distribution over hours in which Gag is initially diffusely localized within the cytoplasm. Plasma membrane signals then accumulate as Gag levels increase and vesicular association appears late, only after plasma membrane site signals have reached high intensity. Lastly, the cell rounds up and HIV protease activation induces diffuse fluorescence throughout the cell. These distinct phases reveal a natural progression of Gag trafficking during the viral gene expression program. HIV Gag-iGFP is a useful tool for dissecting mechanisms of viral assembly and transmission.

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Design of polymeric scaffolds with specific physical and biological properties is a key objective of tissue engineering research. Electrospinning generates loosely connected 3D porous mats simulating extra cellular matrix structure and therefore makes itself an excellent candidate for application in tissue engineering. Besides a high voltage generator and syringe pump, our electrospinning system was improved to add a programmable central controller which monitors system operation. The nozzles connected with syringe pump via silicon rubber tubing can move linearly with a step size of 0.1 microm or above while the mandrel collector rotates at a speed from 400 to 3000 revolutions per minute (rpm). Using this system, porous fiber sheets with fiber diameters ranging from 100 nm to several micrometers or meshes of macroscopically aligned fibers with diameter of approximately 10 microm have been fabricated under proper processing conditions. After biocompatible fibrin coating, oriented polycaprolactone (PCL) fibers were found to enhance the shifting of human umbilical artery smooth muscle cells from synthetic to contractile phenotype, and to maintain biological function of human umbilical vein endothelial cells. We believe that our electrospinning system will facilitate scaffold fabrication for vessel tissue engineering.

wileyonlinelibrary.comconstruction of a new type of multifunctional nanomaterial will be conductive to the diagnosis and treatment integration.Lanthanide nanomaterials have been used extensively as multifunctional imaging probes because of their unique properties. [ 3 ] Due to dysprosium ion (Dy 3+ ) has high magnetic moment (10.6 µ B ) and short electronic relaxation time (≈0.5 ps) [ 4 ] , and lutetium ion (Lu 3+ ) have the heaviest atomic mass among the lanthanides, Dy and Lu-containing nanoparticle can be expected as a potential multifunctional contrast agent for T 2 -weighted MRI and CT imaging. Besides, Prussian blue (PB) is considered as a potential T 1 -weighted MRI agent and photo-induced heating material. However, both magnetic resonance and X-ray attenuation properties can be affected by crystallographic size and number of paramagnetic ions per particle. [ 5 ] Moreover, the therapeutic effect is infl uenced by the ratio of photo-induced heating material in nanocomposites. [ 6 ] Therefore, to utilize certain advantages and maximize imaging and therapy effects, a variety of factors of alternate materials should be considered and compared. However, a limited number of researches include various possibilities.Herein, we synthesized NaDyF 4 doped with different amounts of Lu 3+ ions (NaDyF 4 : x %Lu, x % = 0, 20%, 50%, 80%) via a typical solvothermal method. The T 2 -weighted magnetic resonance and X-ray attenuation properties were discussed to select NaDyF 4 core with an appropriate doping amount for T 2 -weighted MR and CT imaging. The infl uence of PB shell on T 1 -weighted MR and photothermal properties was investigated. Continued efforts have been directed toward treatment of tumor-bearing mice using the selected optimal nanocomposite to detect their therapeutic effi cacy, and their safety was also investigated ( Scheme 1 ). Results and Discussion Synthesis and Characterization of NaDyF 4 : x %LuOleic acid (OA)-coated NaDyF 4 : x %Lu ( x % = 0, 20%, 50%, 80%) nanoparticles ( Figure 1 a) were synthesized by a typical Imaging-guided photothermal therapy based on functional nanomaterials has recently received signifi cant attention and the selection of functional materials with optimal imaging and therapy effect is extremely important. In this work, NaDyF 4 -based nanoparticles with varying size are synthesized by doping with different amounts of lutetium ions. To obtain an optimized material, the infl uence factor of magnetic resonance, X-ray attenuation, and photothermal properties are discussed in detail. Then, NaDyF 4 :50%Lu@Prussian blue (PB) nanocomposite is selected as the optimal functional material for T 1 -and T 2 -weighted magnetic resonance imaging, X-ray computed tomography, and photothermal imaging-guided photothermal therapy of tumor on a small animal model, and the treatment is applied with good results. Studies also suggest that the NaDyF 4 :50%Lu@PB nanocomposites are biocompatibile. The selection of an optimal material from a multi-perspective study has provided an incentive for the ...