We give manifolds whose Riemann curvature operators commute, i.e. which satisfy R(x1, x2)R(x3, x4) = R(x3, x4)R(x1, x2) for all tangent vectors xi in both the Riemannian and the higher signature settings. These manifolds have global geometric phenomena which are quite different for higher signature manifolds than they are for Riemannian manifolds. Our focus is on global properties; questions of...

A digraph D is a 3-anti-circulant digraph, if for any four distinct vertices x1, x2, x3, x4 ∈ V (D), x1 → x2 ← x3 → x4 implies x4 → x1. In this paper, we characterize the structure of 3-anti-circulant digraphs containing a cycle factor and show that the structure is very close to semicomplete and semicomplete bipartite digraphs. Laborde et al. conjectured that every digraph has an independent s...

CD8(+) T-cells secrete soluble factor(s) capable of inhibiting both R5- and X4-tropic strains of human immunodeficiency virus type 1 (HIV-1). CCR5 chemokine ligands, released from activated CD8(+) T-cells, contribute to the antiviral activity of these cells. These CC-chemokines, however, do not account for all CD8(+) T-cell antiviral factor(s) (CAF) released from these cells, particularly becau...

There is evidence that HIV-1 evolution under maraviroc (MVC) pressure can lead to the selection of either X4-tropic variants and/or R5-tropic, MVC-resistant isolates. However, the viral dynamics of HIV-1 variants in patients with virological failure (VF) on MVC-containing regimens remain poorly studied. Here, we investigated the V3 loop evolution of HIV-1 on MVC in relation to coreceptor usage ...

Among HIV-infected individuals, co-infection with Mycobacterium tuberculosis is associated with faster progression to AIDS. We investigated the hypothesis that M. bovis BCG and M. tuberculosis (Mtb complex) could enhance susceptibility of CD4+ cells to HIV infection. Peripheral blood mononuclear cells (PBMCs) collected from healthy donors were stimulated with M. bovis BCG, M. tuberculosis CDC15...

CCR5 and CXCR4, the respective cell surface coreceptors of R5 and X4 HIV-1 strains, both form heterodimers with CD4, the principal HIV-1 receptor. Using several resonance energy transfer techniques, we determined that CD4, CXCR4, and CCR5 formed heterotrimers, and that CCR5 coexpression altered the conformation of both CXCR4/CXCR4 homodimers and CD4/CXCR4 heterodimers. As a result, binding of t...

It has been 15 years since HIV-1 tropism was recognized as a prognostic marker for CD4 T cell depletion and progression to AIDS [1]. The original studies were performed by testing HIV-1 strains for syncytia induction in MT-2 cell culture. These cell-based assays had a sensitivity of detection of 5% and predicted disease progression. They were, however, slow and labor-intensive and thus did not ...

T-cell-derived soluble factors that inhibit both X4 and R5 HIV are recognized as important in controlling HIV. Whereas three β chemokines, regulated-on-activation normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1α, and MIP-1β, account for the suppression of R5 HIV by blockade of HIV entry, the major components responsible for the inhibition of X4 HIV strains...

The quality of walnuts deteriorates owing to the poor shelling equipment. improvement is urgently required for walnut processing. In this study, systematic research was carried out on changes in mechanical properties, model shelling, and key parameters were determined as angles conic roller (X1), speeds (X2), clearance between static (X3), moisture content (X4). Box–Behnken design method used e...

BACKGROUND & AIMS Patients coinfected with HIV-1 and HCV develop more rapid liver fibrosis than patients monoinfected with HCV. HIV RNA levels correlate with fibrosis progression implicating HIV directly in the fibrotic process. While activated hepatic stellate cells (HSCs) express the 2 major HIV chemokine coreceptors, CXCR4 and CCR5, little is known about the pro-fibrogenic effects of the HIV...