The Role of Glucosamine-Induced ER Stress in Diabetic Atherogenesis

Cardiovascular disease (CVD) is the major cause of mortality in individuals with diabetes mellitus. However the molecular and cellular mechanisms that predispose individuals with diabetes to the development and progression of atherosclerosis, the underlying cause of most CVD, are not understood. This paper summarizes the current state of our knowledge of pathways and mechanisms that may link diabetes and hyperglycemia to atherogenesis. We highlight recent work from our lab, and others', that supports a role for ER stress in these processes. The continued investigation of existing pathways, linking hyperglycemia and diabetes mellitus to atherosclerosis, and the identification of novel mechanisms and targets will be important to the development of new and effective antiatherosclerotic therapies tailored to individuals with diabetes

Assay precision and risk of misclassification at rule-out cut-offs for high-sensitivity cardiac troponin

Clinical trials and guidelines support the use of very low high-sensitivity cardiac troponin (hs-cTn) results to rule-out a myocardial infarction (MI) ( 1) ). The International Federation of Clinical Chemistry and Laboratory Medicine Committee on Clinical Applications of Cardiac Biomarkers committee, through a modeling approach, suggests assays need to have a lower limit near 3 ng/L and an analytical variation of 10% below 7 ng/L if these low values are to perform consistently in practice ( 2) ). Our objectives for the present study were to assess: i) if any type of instrument or individual instrument could achieve a coefficient of variation (CV) of ≤10% at very low hs-cTn cut-offs (i.e., targets) recommended in clinical pathways; ii) the frequency of results at the hs-cTn target, above the target and below the target, with the latter group representing potential misclassification to the low risk group where the target level would in the intermediate risk range.<br/

HIV-1 Matrix Dependent Membrane Targeting Is Regulated by Gag mRNA Trafficking

Retroviral Gag polyproteins are necessary and sufficient for virus budding. Productive HIV-1 Gag assembly takes place at the plasma membrane. However, little is known about the mechanisms by which thousands of Gag molecules are targeted to the plasma membrane. Using a bimolecular fluorescence complementation (BiFC) assay, we recently reported that the cellular sites and efficiency of HIV-1 Gag assembly depend on the precise pathway of Gag mRNA export from the nucleus, known to be mediated by Rev. Here we describe an assembly deficiency in human cells for HIV Gag whose expression depends on hepatitis B virus (HBV) post-transcriptional regulatory element (PRE) mediated-mRNA nuclear export. PRE-dependent HIV Gag expressed well in human cells, but assembled with slower kinetics, accumulated intracellularly, and failed to associate with a lipid raft compartment where the wild-type Rev-dependent HIV-1 Gag efficiently assembles. Surprisingly, assembly and budding of PRE-dependent HIV Gag in human cells could be rescued in trans by co-expression of Rev-dependent Gag that provides correct membrane targeting signals, or in cis by replacing HIV matrix (MA) with other membrane targeting domains. Taken together, our results demonstrate deficient membrane targeting of PRE-dependent HIV-1 Gag and suggest that HIV MA function is regulated by the trafficking pathway of the encoding mRNA

Mitochondrial Lactate Dehydrogenase Is Involved in Oxidative-Energy Metabolism in Human Astrocytoma Cells (CCF-STTG1)

Lactate has long been regarded as an end product of anaerobic energy production and its fate in cerebral metabolism has not been precisely delineated. In this report, we demonstrate, for the first time, the ability of a human astrocytic cell line (CCF-STTG1) to consume lactate and to generate ATP via oxidative phosphorylation. 13C-NMR and HPLC analyses aided in the identification of tricarboxylic acid (TCA) cyle metabolites and ATP in the astrocytic mitochondria incubated with lactate. Oxamate, an inhibitor of lactate dehydrogenase (LDH), abolished mitochondrial lactate consumption. Electrophoretic and fluorescence microscopic analyses helped localize LDH in the mitochondria. Taken together, this study implicates lactate as an important contributor to ATP metabolism in the brain, a finding that may significantly change our notion of how this important organ manipulates its energy budget