Apolipoprotein B (ApoB) is a key marker of atherogenic lipoprotein burden, but conventional plasma-based testing requires venous sampling and centralized laboratory infrastructure. Dried blood spot (D Show more
Apolipoprotein B (ApoB) is a key marker of atherogenic lipoprotein burden, but conventional plasma-based testing requires venous sampling and centralized laboratory infrastructure. Dried blood spot (DBS) sampling offers a minimally invasive alternative suitable for decentralized settings. This study evaluated the analytical performance of a DBS-based ApoB assay on the Chem7 semi-automated analyser and compared it with the Abbott ARCHITECT ci4100 plasma reference method. DBS samples prepared from 50 de-identified EDTA whole-blood specimens were extracted in saline and analysed using an immunoturbidimetric ApoB assay on the Chem7 analyser with a correction factor of 2 applied for haematocrit dilution. Paired plasma specimens were analysed on the ARCHITECT ci4100. Method comparison included Passing-Bablok and Deming regression and Bland-Altman analysis. Potential outliers were assessed using Grubbs' test ( Show less
Chromatin is highly dynamic and subject to extensive remodeling under many physiologic conditions. Changes in chromatin that occur during the aging process are poorly documented and understood in high Show more
Chromatin is highly dynamic and subject to extensive remodeling under many physiologic conditions. Changes in chromatin that occur during the aging process are poorly documented and understood in higher organisms, such as mammals. We developed an immunofluorescence assay to quantitatively detect, at the single cell level, changes in the nuclear content of chromatin-associated proteins. We found increased levels of the heterochromatin-associated proteins histone macro H2A (mH2A) and heterochromatin protein 1 beta (HP1β) in human fibroblasts during replicative senescence in culture, and for the first time, an age-associated increase in these heterochromatin marks in several tissues of mice and primates. Mouse lung was characterized by monophasic mH2A expression histograms at both ages, and an increase in mean staining intensity at old age. In the mouse liver, we observed increased age-associated localization of mH2A to regions of pericentromeric heterochromatin. In the skeletal muscle, we found two populations of cells with either low or high mH2A levels. This pattern of expression was similar in mouse and baboon, and showed a clear increase in the proportion of nuclei with high mH2A levels in older animals. The frequencies of cells displaying evidence of increased heterochromatinization are too high to be readily accounted for by replicative or oncogene-induced cellular senescence, and are prominently found in terminally differentiated, postmitotic tissues that are not conventionally thought to be susceptible to senescence. Our findings distinguish specific chromatin states in individual cells of mammalian tissues, and provide a foundation to investigate further the progressive epigenetic changes that occur during aging. Show less