👤 Natalia Mast

Drusen and subretinal drusenoid deposits, the pathognomonic lesions for age-related macular degeneration (AMD), are rich in cholesterol. Yet, AMD is not consistently linked to plasma lipids. Here wild-type and human apolipoprotein B100-expressing (APOB100) mice were put on a Western type of diet for 13 months and then assessed for plasma lipid profile, high-density lipoprotein (HDL) heterogeneity, status of intraretinal and choroidal vasculatures, retinal structure, function, levels of cholesterol and other sterols, lipid and cholesterol distribution and expression of cholesterol-related genes. The dietary effects were more pronounced in APOB100 mice, which had human-like hyperlipidemia and different subpopulations of HDL Show less

Genetics play a significant role in coagulation phenotype and venous thromboembolism risk. Resistance to the anticoagulant activated protein C (APC) is an established risk for thrombosis. Herein, we explored the genetic determinants of thrombin generation (TG) and thrombomodulin (TM)-modulated TG using plasma from the Human Functional Genomics Project. Calibrated TG was measured both in absence and presence of TM using tissue factor as trigger. Genetic determinants of TG parameters and protein C pathway function were assessed using genome-wide single-nucleotide polymorphism (SNP) genotyping. Plasma samples were supplemented with purified apolipoprotein A-IV, prekallikrein, or kallikrein to test their influence on the anticoagulant function of TM and APC in TG. Thrombin generation data from 392 individuals were analyzed. Genotyping showed that the KLKB1 gene (top SNP: rs4241819) on chromosome 4 was associated with the normalized sensitivity ratio of endogenous thrombin potential to TM at genome-wide level (nETP-TMsr, P = 4.27 × 10 Our results suggest that kallikrein plays a role in the regulation of the anticoagulant protein C pathway in TG, which may provide a novel mechanism for the previously observed association between the KLKB1 gene and venous thrombosis. Show less

Apolipoprotein E (APOE) is a component of lipid-transporting particles and a recognition ligand for receptors, which bind these particles. The APOE isoform ε2 is a risk factor for age-related macular degeneration; nevertheless, APOE absence in humans and mice does not significantly affect the retina. We found that retinal cholesterol biosynthesis and the levels of retinal cholesterol were increased in Show less

Tissue factor pathway inhibitor (TFPI) is an endothelial-associated inhibitor of blood coagulation. Because the mechanism for attachment of TFPI to endothelium is not clear, we investigated its association with human placenta. Western blots demonstrate that treatment with phosphatidylinositol-specific phospholipase C (PIPLC) removes more placental TFPI than either PBS or heparin, a finding confirmed by immunohistochemistry. The amounts of heparin-releasable and PIPLC-releasable TFPI activity on placental endothelium were measured in placentas from 5 individuals. PIPLC removes >10-fold more TFPI activity from the placental fragments than 10 U/mL heparin and >100-fold more than 1 U/mL heparin. Pretreatment of the placental fragments with PIPLC increases the amount of heparin-releasable TFPI by approximately 3-fold. An antibody specific for the C-terminal region of TFPI recognizes PIPLC-releasable TFPI in Western blots. GPI-anchored TFPI is the predominant form on placental endothelium. Heparin-releasable TFPI likely represents only a small portion of the total TFPI on endothelium that remains attached to cell-surface glycosaminoglycans after cleavage of the GPI anchor by endogenous enzymes. The predominance of GPI-anchored TFPI suggests that heparin infusion does not significantly redistribute TFPI within the vasculature. The intact C-terminus in GPI-anchored TFPI indicates it is not directly attached to a GPI anchor. Rather, it most likely associates with endothelium by binding to a GPI-anchored protein. Show less

Determination of the reticulocyte hemoglobin content (CHr) provides an early measure of functional iron deficiency because reticulocytes are the earliest erythrocytes released into blood and circulate for only 1 to 2 days. The CHr in 78 patients undergoing bone marrow examination was measured to assess its clinical utility for the diagnosis of iron deficiency. Twenty-eight patients were iron deficient, based on the lack of stainable iron in the aspirate. The diagnostic power of CHr is limited in patients with high mean cellular volume (MCV) or red cell disorders such as thalassemia. However, when patients with MCV more than 100 fL are excluded, receiver operator curve analysis of CHr, ferritin, transferrin saturation, and MCV demonstrates that CHr has the highest overall sensitivity and specificity of these peripheral blood tests for predicting the absence of bone marrow iron stores. Show less