An LC-MS/MS assay for analysis of equilibrium angiotensin II in human serum.

Background: The current first-line screening test for primary hyperaldosteronism is the plasma aldosterone:renin ratio; however, renin assays have several disadvantages and the ARR is affected by medications and physiological factors. Angiotensin II is a key biologically active hormone in the renin-angiotensin-aldosterone system. It has been suggested that measurement of equilibrium levels of this peptide, involving an incubation of serum prior to analysis, may provide a better marker of renin-angiotensin-aldosterone system activity than renin.

A simplified, rapid LC-MS/MS assay for serum and salivary creatinine.

In routine clinical laboratories, serum creatinine is typically measured on automated analyzers using colorimetric or enzymatic assays, which are both susceptible to interferences that can lead to incorrect measurement. Here, we present a straightforward and rapid LC-MS/MS assay for serum creatinine using methanol extraction, with separation performed using a strong cation exchange column. Results from this newly developed method were compared against those from an automated Abbott Architect kinetic Jaffe method.

Several commercially available anti-CCR5 monoclonal antibodies lack specificity and should be used with caution.

CCR5 (CD195) is a receptor for the chemokines RANTES, MIP-1α, and MIP-1β and is used by HIV-1 as a co-receptor for entry into macrophages and CD4+ T cells. CCR5 exists in multiple conformations in the membrane and is present at low levels on human macrophages, making it difficult to detect. Nine commercially available anti-CCR5 monoclonal antibodies were evaluated for their specificity and their recognition of CCR5 expressed by macrophages.

HIV-1 infects macrophages by exploiting an endocytic route dependent on dynamin, Rac1 and Pak1.

Recent studies provide compelling evidence that HIV-1 entry in cell lines and lymphocytes proceeds by endocytosis, but these studies are still lacking in macrophages, an important natural target cell for HIV-1. Macrophages exhibit continual and extensive endocytic activity as part of their natural functions, so we investigated the uptake pathways involved in productive HIV-1 entry. We find that caveolae are not utilised by HIV-1, because the main structural proteins, caveolin-1 and 2 are absent from most human leukocytes.

HIV entry in macrophages is dependent on intact lipid rafts.

Macrophages are an important natural target cell for HIV-1, but previous studies of virus entry into these cells are limited, and the involvement of membrane cholesterol and lipid rafts is unknown. Cholesterol disruption of macrophage membranes using four pharmacological agents acting by different mechanisms: methyl-beta cyclodextrin, nystatin, filipin complex and Lovastatin, all significantly inhibited productive HIV entry and reverse transcription. The inhibitory effects of these drugs resulted in decreased virus release from infected cells, and could be substantially reversed by the addition of water-soluble cholesterol.