Nuclear Apaf-1 and cytochrome c redistribution following stress-induced apoptosis

AbstractApoptotic protease activating factor-1 (Apaf-1) and cytochrome c are cofactors critical for inducing caspase-9 activation following stress-induced apoptosis. One consequence of caspase-9 activation is nuclear–cytoplasmic barrier disassembly, which is required for nuclear caspase-3 translocation. In the nucleus, caspase-3 triggers proteolysis of the caspase-activated DNA nuclease (CAD) inhibitor, causing CAD induction and subsequent DNA degradation. Here we demonstrate that apoptotic cells show perinuclear cytochrome c aggregation, which may be critical for nuclear redistribution of cytochrome c and Apaf-1. We thus indicate that the nuclear redistribution of these cofactors concurs with the previously reported caspase-9-induced nuclear disassembly, and may represent an early apoptotic hallmark

Bubble size distribution resulting from the breakup of an air cavity injected into a turbulent water jet

We investigated experimentally the shape of the final size PDF(D) resulting from the breakup of an air bubble injected into the fully developed region of a high Reynolds number turbulent water jet. It is shown that the PDF(Dcirc) of the normalized bubble size Dcirc=D/D32, where D32 is the Sauter mean diameter of the distribution, has a universal single shape independent of the value of the turbulent kinetic energy of the water jet at the bubble injection point and of the air void fraction, α. The shape of the exponential tails characterizing each PDF(D) is shown to be only a function of the initial bubble size D0 and the critical bubble size Dc, defined as Dc=(1.46σ/ρ)3/5ɛ-2/5, where ɛ is the value of the dissipation rate of turbulent kinetic energy per unit mass at the air injection point

Laminar Craya-Curtet jets

This Brief Communication investigates laminar Craya-Curtet flows, formed when a jet with moderately large Reynolds number discharges into a coaxial ducted flow of much larger radius. It is seen that the Craya-Curtet number, C=(J/sub c//J/sub j/)/sup 1/2/, defined as the square root of the ratio of the momentum flux of the coflowing stream to that of the central jet, arises as the single governing parameter when the boundary-layer approximation is used to describe the resulting steady slender jet. The numerical integrations show that for C above a critical value C/sub c/ the resulting streamlines remain aligned with the axis, while for C<C/sub c/ the entrainment demands of the jet cannot be satisfied by the coflow, and a toroidal recirculation region forms. The critical Craya-Curtet number is determined for both uniform and parabolic coflow, yielding C/sub c/=0.65 and C/sub c/=0.77, respectively. The streamlines determined numerically are compared with those obtained experimentally by flow visualizations, yielding good agreement in the resulting flow structure and also in the value of C/sub c

A potential immune escape mechanism by melanoma cells through the activation of chemokine-induced T cell death

AbstractThe immune system attempts to prevent or limit tumor growth, yet efforts to induce responses to tumors yield minimal results, rendering tumors virtually invisible to the immune system [1]. Several mechanisms may account for this subversion, including the triggering of tolerance to tumor antigens [2, 3], TGF-α or IL-10 production, downregulation of MHC molecules, or upregulation of FasL expression [4, 5]. Melanoma cells may in some instances use FasL expression to protect themselves against tumor-infiltrating lymphocytes (TIL) [4, 5]. Here, we show another, chemokine-dependent mechanism by which melanoma tumor cells shield themselves from immune reactions. Melanoma-inducible CCL5 (RANTES) production by infiltrating CD8 cells activates an apoptotic pathway in TIL involving cytochrome c release into the cytosol and activation of caspase-9 and -3. This process, triggered by CCL5 binding to CCR5, is not mediated by TNFα, Fas, or caspase-8. The effect is not unique to CCL5, as other CCR5 ligands such as CCL3 (MIP-1α) and CCL4 (MIP-1β) also trigger TIL cell death, nor is it limited to melanoma cells, as it also operates in activated primary T lymphocytes. The model assigns a role to the CXC chemokine CXCL12 (SDF-1α) in this process, as this melanoma cell-produced chemokine upregulates CCL5 production by TIL, initiating TIL cell death

Expression analysis of the thyrotropin-releasing hormone receptor (TRHR) in the immune system using agonist anti-TRHR monoclonal antibodies

AbstractMonoclonal anti-rat thyrotropin-releasing hormone (TRH) receptor (TRHR)-specific antibodies (mAb) were generated by immunization with synthetic peptides of rat TRHR partial amino acid sequences; one (TRHR01) was directed against a sequence (84–98) in the extracellular portion of the rat TRHR reported to be constant among different species, including man, and the second (TRHR02) recognizes the C-terminal region sequence 399–412. In lysates from GH4C1 cells, a clonal rat pituitary cell line, both mAb recognize the TRHR in Western blot analysis, and TRHR02 immunoprecipitates the TRHR. Incubation of GH4C1 cells with the mAb causes a fluorescence shift in fluorescence-activated cell sorting analysis. The cells were stained specifically by both mAb using immunocytochemical techniques. Furthermore, TRHR01 is agonistic in its ability to trigger Ca2+ flux, and desensitizes the TRH receptor. We tested for TRHR in several rat organs and found expression in lymphoid tissues. TRHR01 recognizes the human TRHR, and analysis of human peripheral blood lymphocyte and tonsil-derived leukocyte populations showed receptor expression in non-activated and phytohemagglutinin-activated T and B cells

DFT and Kinetic Monte Carlo Study of TMS-Substituted Ruthenium Vinyl Carbenes: Key Intermediates for Stereoselective Cyclizations

Mechanistic pathways for the cyclization of 1,5-alkynylacetal with N₂CHTMS in the presence of Cp- and Cp*RuCl­(cod) to afford (<i>Z</i>)- and (<i>E</i>)-(trimethylsilyl)­vinyl spiroacetals have been calculated. Calculations show the presence of three conformers in equilibrium for the initially formed ruthenium carbenes. Differences in the stabilities and reactivities of the conformers, depending on the use of a Cp or Cp* ruthenium catalyst, are responsible for the favorable active reaction pathways in each case, even though the geometry of the resulting product is the same regardless of the catalyst used. Kinetic Monte Carlo (KMC) simulations with rate coefficients, including tunneling probabilities for the hydride transfer step, were used to model the evolution of reactants, intermediates, and products for all calculated pathways. It was shown that one path is almost exclusively active for each catalyst. Finally, the energetic span model of Kozuch and Shaik was used to calculate the energetic span (δ<i>E</i>), the TOF-determining transition state (TDTS), the TOF-determining intermediate (TDI), and the TOF value for each of the feasible mechanistic pathways

Synthesis of Pt Nanoparticles in Water-in-Oil Microemulsion: Effect of HCl on Their Surface Structure

The synthesis of shape-controlled nanoparticles is currently a hot research topic. However, from an applied point of view, there is still a lack of easy, cheap, and scalable methodologies. In this communication we report, for the first time, the synthesis of cubic platinum nanoparticles with a very high yield using a water-in-oil microemulsion method, which unlike others, such as the colloidal method, fulfills the previous requirements. This shape/surface structure control is determined by the concentration of HCl in the water phase of the microemulsion. The results reported here show that the optimal HCl percentage in the water phase is about 25% to obtain the highest amount of cubic nanostructures. Ammonia electro-oxidation is used as a surface structure sensitive reaction to illustrate HCl surface structure effects. Moreover, in situ electrochemical characterization has been performed to study the nanoparticle surface structure

8‑Alkoxy- and 8‑Aryloxy-BODIPYs: Straightforward Fluorescent Tagging of Alcohols and Phenols

We demonstrate herein that both alcohols and phenols can be tagged with a BODIPY (borondipyrromethene) moiety to yield highly fluorescent products. Thus, 8-(methylthio)-BODIPY (<b>1</b>) undergoes an S_NAr-type reaction with a host of alcohols and phenols in the presence of a base and a Cu­(I) additive. The BODIPY dyes bearing alkoxy or nonfunctionalized phenoxy moieties are characterized by a highly efficient fluorescence emission, regardless of the media, in the blue-green part of the visible region. Complementary to this, the presence of electron-donor groups at the aryl ring leads to an intramolecular charge-transfer process, which quenches the fluorescence mainly in polar media. In addition to simple alcohols and phenols, four natural products (eugenol, menthol, cholesterol, and estrone) were labeled in a simple fashion. X-ray structures of the cholesterol and estrone derivatives are discussed. In fact, the BODIPY bearing cholesterol stands out as a bright fluorescence biological marker