Inhibition of DNA ejection from bacteriophage by Mg+2 counterions

The problem of inhibiting viral DNA ejection from bacteriophages by multivalent counterions, specifically Mg$^{+2}$ counterions, is studied. Experimentally, it is known that MgSO$_4$ salt has a strong and non-monotonic effect on the amount of DNA ejected. There exists an optimal concentration at which the minimum amount of DNA is ejected from the virus. At lower or higher concentrations, more DNA is ejected from the capsid. We propose that this phenomenon is the result of DNA overcharging by Mg$^{+2}$ multivalent counterions. As Mg$^{+2}$ concentration increases from zero, the net charge of DNA changes from negative to positive. The optimal inhibition corresponds to the Mg$^{+2}$ concentration where DNA is neutral. At lower/higher concentrations, DNA genome is charged. It prefers to be in solution to lower its electrostatic self-energy, which consequently leads to an increase in DNA ejection. By fitting our theory to available experimental data, the strength of DNA$-$DNA short range attraction energies, mediated by Mg$^{+2}$, is found to be $-$0.004 $k_BT$ per nucleotide base. This and other fitted parameters agree well with known values from other experiments and computer simulations. The parameters are also in aggreement qualitatively with values for tri- and tetra-valent counterions.Comment: 17 pages, 4 figures, improved manuscript. Submitted to J. Chem. Phys (2010

Sonification using digital waveguides and 2- and 3-dimensional digital waveguide mesh

Presented at the 11th International Conference on Auditory Display (ICAD2005)We describe a method of auditory display of complex data, object identification, and classification using digital waveguides and waveguide mesh. Our overall goal is to distinguish highly dimensional data sets from one another in such a way that reveals meaningful differences in a particular context. In this paper we provide a summary of the application of waveguide and waveguide mesh architectures to sonification, and demonstrate the digital waveguide, 2- and 3-dimensional mesh in a variety of sonification tasks

Supercontinuum Generation in a Silica Spiral Waveguide

A low-loss silica spiral waveguide is used for demonstrating on-chip supercontinuum generation. The broadest measured spectrum spans an octave (936 – 1888 nm) at −50 dB from peak when 2.17 nJ pulses are launched

Palmitoleic acid prevents palmitic acid-induced macrophage activation and consequent p38 MAPK-mediated-skeletal muscle insulin resistance

Obesity and saturated fatty acid (SFA) treatment are both associated with skeletal muscle insulin resistance (IR) and increased macrophage infiltration. However, the relative effects of SFA and unsaturated fatty acid (UFA)-activated macrophages on muscle are unknown. Here, macrophages were treated with palmitic acid, palmitoleic acid or both and the effects of the conditioned medium (CM) on C2C12 myotubes investigated. CM from palmitic acid-treated J774s (palm-mac-CM) impaired insulin signalling and insulin-stimulated glycogen synthesis, reduced Inhibitor κBα and increased phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase in myotubes. p38 MAPK inhibition or siRNA partially ameliorated these defects, as did addition of tumour necrosis factor-α blocking antibody to the CM. Macrophages incubated with both FAs generated CM that did not induce IR, while palmitoleic acid-mac-CM alone was insulin sensitising. Thus UFAs may improve muscle insulin sensitivity and counteract SFA-mediated IR through an effect on macrophage activation

Anomalous diffusion in polymers: long-time behaviour

We study the Dirichlet boundary value problem for viscoelastic diffusion in polymers. We show that its weak solutions generate a dissipative semiflow. We construct the minimal trajectory attractor and the global attractor for this problem.Comment: 13 page

Supercontinuum generation in an on-chip silica waveguide

Supercontinuum generation is demonstrated in an on-chip silica spiral waveguide by launching 180 fs pulses from an optical parametric oscillator at the center wavelength of 1330 nm. With a coupled pulse energy of 2.17 nJ, the broadest spectrum in the fundamental TM mode extends from 936 to 1888 nm (162 THz) at −50  dB from peak. There is a good agreement between the measured spectrum and a simulation using a generalized nonlinear Schrödinger equation

The Biology of Cancer Stem Cells and Its Clinical Implication in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor with limited treatment options in its advanced state. The molecular mechanisms underlying HCC remain unclear because of the complexity of its multi-step development process. Cancer stem cells (CSCs) are defined as a small population of cells within a tumor that possess the capability for self-renewal and the generation of heterogeneous lineages of cancer cells. To date, there have been two theories concerning the mechanism of carcinogenesis, i.e., the stochastic (clonal evolution) model and the hierarchical (cancer stem cell-driven) model. The concept of the CSC has been established over the past decade, and the roles of CSCs in the carcinogenic processes of various cancers, including HCC, have been emphasized. Previous experimental and clinical evidence indicated the existence of liver CSCs; however, the potential mechanistic links between liver CSCs and the development of HCC in humans are not fully understood. Although definitive cell surface markers for liver CSCs have not yet been found, several putative markers have been identified, which allow the prospective isolation of CSCs from HCC. The identification and characterization of CSCs in HCC is essential for a better understanding of tumor initiation or progression in relation to signaling pathways. These markers could be used along with clinical parameters for the prediction of chemoresistance, radioresistance, metastasis and survival and may represent potential targets for the development of new molecular therapies against HCC. This review describes the current evidence for the existence and function of liver CSCs and discuss the clinical implications of CSCs in patients demonstrating resistance to conventional anti-cancer therapies, as well as clinical outcomes. Such data may provide a future perspective for targeted therapy in HCC