HIV-1 Directly Kills CD4+ T Cells by a Fas-independent Mechanism

The mechanism by which HIV-1 induces CD4+ T cell death is not known. A fundamental issue is whether HIV-1 primarily induces direct killing of infected cells or indirectly causes death of uninfected bystander cells. This question was studied using a reporter virus system in which infected cells are marked with the cell surface protein placental alkaline phosphatase (PLAP). Infection by HIV-PLAP of peripheral blood mononuclear cells (PBMCs) and T cell lines leads to rapid depletion of CD4+ T cells and induction of apoptosis. The great majority of HIV-induced T cell death in vitro involves direct loss of infected cells rather than indirect effects on uninfected bystander cells. Because of its proposed role in HIV-induced cell death, we also examined the Fas (CD95/Apo1) pathway in killing of T cells by HIV-1. Infected PBMCs or CEM cells display no increase in surface Fas relative to uninfected cells. In addition, HIV-1 kills CEM and Jurkat T cells in the presence of a caspase inhibitor that completely blocks Fas-mediated apoptosis. HIV-1 also depletes CD4+ T cells in PBMCs from patients who have a genetically defective Fas pathway. These results suggest that HIV-1 induces direct apoptosis of infected cells and kills T cells by a Fas-independent mechanism

Modelling the Effects of Intangible Capabilities on ERP Implementation

Enterprise resource planning (ERP) system is well recognised as a key technological infrastructure that facilitates business operations and growth in a dynamic business environment. Implementation of ERP system however is mirrored by numerous problems, a fact well cited in many academic studies. Research addressing the reasons for ERP implementation problems has identified a plethora of success factors. Following a similar research direction, we leveraged on the resource based view (RBV) to investigate the effects of firms’ capacity to deploy intangible resources with valuable and inimitable characteristics (termed as intangible capabilities) on successful ERP implementation. Three intangible capabilities were assessed, i.e. governance, knowledge and relationships. Using data collected from a survey with service firms in Malaysia, we found evidence that relationships capability effect towards successful ERP implementation was direct and significant. Further analysis revealed that governance capability reinforces the effects of knowledge and relationship capabilities toward successful ERP implementation. The empirical findings suggest that successful ERP implementation lie at the firms’ capacity to deploy and reconfigure their intangible capabilities of valuable and inimitable characteristics to create reinforcing superseding effects. We conclude that governance capability plays the antecedent platform role to strengthen the effects of knowledge and relationships capabilities on ERP project’s success

The influence of tropospheric biennial oscillation on mid-tropospheric CO_2

Mid-tropospheric CO_2 retrieved from the Atmospheric Infrared Sounder (AIRS) was used to investigate CO_2 interannual variability over the Indo-Pacific region. A signal with periodicity around two years was found for the AIRS mid-tropospheric CO_2 for the first time, which is related to the Tropospheric Biennial Oscillation (TBO) associated with the strength of the monsoon. During a strong (weak) monsoon year, the Western Walker Circulation is strong (weak), resulting in enhanced (diminished) CO_2 transport from the surface to the mid-troposphere. As a result, there are positive (negative) CO2 anomalies at mid-troposphere over the Indo-Pacific region. We simulated the influence of the TBO on the mid-tropospheric CO_2 over the Indo-Pacific region using the MOZART-2 model, and results were consistent with observations, although we found the TBO signal in the model CO_2 is to be smaller than that in the AIRS observations