Cellular search migrations in normal development and carcinogenesis

This review describes the large group of morphogenetic processes designated as search migrations. Search migrations typically include two stages: i) search, when a group of cells or of the cytoplasmic processes migrate over the cell-free spaces, and ii) choice, the stage when migrating cells reach specific loci where they stop and undergo specific differentiations induced by local factors such as cell-cell contacts and humoral agents. Migrating cells that do not meet their targets usually undergo apoptosis. Numerous examples of search migrations range from gastrulation to formation of axon-muscle connections. Critical stages of carcinogenesis such as acquisition of cell ability for invasion may be regarded as the genetic aberration of normal search migration: cancer cells perform an endless search but cannot make final choice.     

Quantification of atherosclerotic plaque activity and vascular inflammation using [18-F] fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT)

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC) and carotid intimal medial thickness (C-IMT) provide information about the burden of disease. However, despite multiple validation studies of CAC, and C-IMT, these modalities do not accurately assess plaque characteristics, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events. [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity, an important source of cellular inflammation in vessel walls. More recently, we and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors and is also highly associated with overall burden of atherosclerosis. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy as well as longer term therapeutic lifestyle changes (16 months). The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.     

α–E-catenin binds to dynamitin and regulates dynactin-mediated intracellular traffic

α–Epithelial catenin (E-catenin) is an important cell–cell adhesion protein. In this study, we show that α–E-catenin also regulates intracellular traffic by binding to the dynactin complex component dynamitin. Dynactin-mediated organelle trafficking is increased in α–E-catenin^−/− keratinocytes, an effect that is reversed by expression of exogenous α–E-catenin. Disruption of adherens junctions in low-calcium media does not affect dynactin-mediated traffic, indicating that α–E-catenin regulates traffic independently from its function in cell–cell adhesion. Although neither the integrity of dynactin–dynein complexes nor their association with vesicles is affected by α–E-catenin, α–E-catenin is necessary for the attenuation of microtubule-dependent trafficking by the actin cytoskeleton. Because the actin-binding domain of α–E-catenin is necessary for this regulation, we hypothesize that α–E-catenin functions as a dynamic link between the dynactin complex and actin and, thus, integrates the microtubule and actin cytoskeleton during intracellular trafficking.     

Hyperinsulinemia fails to augment ET-1 action in the skeletal muscle vascular bed in vivo in humans

Endogenous endothelin action is augmented in human obesity and type 2 diabetes and contributes to endothelial dysfunction and impairs insulin-mediated vasodilation in humans. We hypothesized that insulin resistance-associated hyperinsulinemia could preferentially drive endothelin-mediated vasoconstriction. We applied hyperinsulinemic-euglycemic clamps with higher insulin dosing in obese subjects than lean subjects (30 vs. 10 mU.m(-2).min(-1), respectively), with the goal of matching insulin's nitric oxide (NO)-mediated vascular effects. We predicted that, under these circumstances, insulin-stimulated endothelin-1 (ET-1) action (assessed with the type A endothelin receptor antagonist BQ-123) would be augmented in proportion to hyperinsulinemia. NO bioactivity was assessed using the nitric oxide synthase inhibitor N(G)-monomethyl-l-arginine. Insulin-mediated vasodilation and insulin-stimulated NO bioavailability were well matched across groups by this approach. As expected, steady-state insulin levels were approximately threefold higher in obese than lean subjects (109.2 +/- 10.2 pmol/l vs. 518.4 +/- 84.0, P = 0.03). Despite this, the augmentation of insulin-mediated vasodilation by BQ-123 was not different between groups. ET-1 flux across the leg was not augmented by insulin alone but was increased with the addition of BQ-123 to insulin (P = 0.01 BQ-123 effect, P = not significant comparing groups). Endothelin antagonism augmented insulin-stimulated NO bioavailability and NOx flux, but not differently between groups and not proportional to hyperinsulinemia. These findings do not support the hypothesis that insulin resistance-associated hyperinsulinemia preferentially drives endothelin-mediated vasoconstriction.     

Identification of Horizontal Gene Transfer from Phylogenetic Gene Trees

We suggest a new procedure to search for the genes with horizontal transfer events in their evolutionary history. The search is based on analysis of topology difference between the phylogenetic trees of gene (protein) groups and the corresponding phylogenetic species trees. Numeric values are introduced to measure the discrepancy between the trees. This approach was applied to analyze 40 prokaryotic genomes classified into 132 classes of orthologs. This resulted in a list of the candidate genes for which the hypothesis of horizontal transfer in evolution looks true.     

Cold-stable microtubules in the cytoplasm of mouse embryo fibroblasts.

Treatment of cultured mouse embryo fibroblasts with Triton X-100 after prolonged incubation at 0 degrees C reveals a network of microtubules in the cytoplasm of cooled cells. This network of cold-stable microtubules was demonstrated by immunofluorescence microscopy, using a monospecific antibody against tubulin and by electron microscopy. The cold-stable microtubules, as well as the ordinary cytoplasmic microtubules, were sensitive to Ca ions and were not observed in the cells pre-treated with colchicine or vinblastine. The cold-stable microtubules do not seem to be in equilibrium with the pool of depolymerized tubulin at 0 degrees C.