Identification and characterization of novel amphioxus microRNAs by Solexa sequencing

An analysis of amphioxus miRNAs suggests an expansion of miRNAs played a key role in the evolution of chordates to vertebrate

PGC-1α Is a Key Regulator of Glucose-Induced Proliferation and Migration in Vascular Smooth Muscle Cells

BACKGROUND: Atherosclerosis is a complex pathological condition caused by a number of mechanisms including the accelerated proliferation of vascular smooth muscle cells (VSMCs). Diabetes is likely to be an important risk factor for atherosclerosis, as hyperglycemia induces vascular smooth muscle cell (VSMC) proliferation and migration and may thus contribute to the formation of atherosclerotic lesions. This study was performed to investigate whether PGC-1alpha, a PPARgamma coactivator and metabolic master regulator, plays a role in regulating VSMC proliferation and migration induced by high glucose. METHODOLOGY/PRINCIPAL FINDINGS: PGC-1alpha mRNA levels are decreased in blood vessel media of STZ-treated diabetic rats. In cultured rat VSMCs, high glucose dose-dependently inhibits PGC-1alpha mRNA expression. Overexpression of PGC-1alpha either by infection with adenovirus, or by stimulation with palmitic acid, significantly reduces high glucose-induced VSMC proliferation and migration. In contrast, suppression of PGC-1alpha by siRNA mimics the effects of glucose on VSMCs. Finally, mechanistic studies suggest that PGC-1alpha-mediated inhibition of VSMC proliferation and migration is regulated through preventing ERK1/2 phosphorylation. CONCLUSIONS/SIGNIFICANCE: These results indicate that PGC-1alpha is a key regulator of high glucose-induced proliferation and migration in VSMCs, and suggest that elevation of PGC-1alpha in VSMC could be a useful strategy in preventing the development of diabetic atherosclerosis

Mechanical Properties and Microstructure of Hot-Pressed Silica Matrix Composites

Silica is one of the most widely used ceramics due to its excellent chemical stability and dielectric property. However, its destructive brittle nature inhabits it from wider application as a functional ceramic. An improvement in toughness is a challenging topic for silica ceramic, as well as other ceramics. In the paper, silica ceramic with different types of boron nitride powders and alumina platelets was fabricated by hot-pressing. Introduction of the additives had great influence on the composites’ mechanical properties and microstructure. The silica matrix composite containing micro-sized boron nitride powders possessed the best mechanical properties, including the bending strength (134.5 MPa) and the fracture toughness (1.85 Mpa·m1/2). Meanwhile, the introduction of alumina platelets combined with boron nitride nanosheets achieved an effective enhancement of fracture toughness while maintaining the bending strength. Compared with the monolithic silica, the composite with simultaneous addition of alumina platelets and boron nitride nanosheets had a fracture toughness of 2.23 Mpa·m1/2, increased by approximately 27% (1.75 Mpa·m1/2). The crack deflection and platelet pullout were contributing to enhancement of the fracture toughness. The improved mechanical properties, combined with the intrinsic excellent dielectric and chemical properties, make the silica matrix composites promising wave transparent and thermal protection materials

Molecular Dynamics Simulation of the Effects of Methane Hydrate Phase Transition on Mechanical Properties of Deep-Sea Methane Hydrate-Bearing Soil

In this paper, the methane hydrate phase transition process in deep-sea methane hydrate-bearing soil under heating and compression was simulated by the molecular dynamics method. The evolution of deep-sea methane hydrate-bearing soil’s microstructure, system energy, intermolecular interaction energy, and radial distribution function during heating and compression was investigated. The micromechanism of the influence of the methane hydrate phase transition on the mechanical properties of deep-sea methane hydrate-bearing soil was analyzed. The results demonstrated that the methane hydrate dissociation starts from both sides to the middle and the void spaces between the soil particles had nearly no change during the heating process. For the compression process, the methane hydrate on both sides and the middle dissociated at the same time, and the void spaces became smaller. The methane hydrate phase transition on the effects of mechanical properties of the deep-sea methane hydrate-bearing soil is mainly caused by three aspects. (1) the dissociation of methane hydrate incurs the decrease of methane hydrate saturation. The free water and methane molecules generated cannot migrate in time and thus lead to the increase of excess pore water press and excess pore gas press. (2) The dissipated energy causes the decrease of the effective stress between the soil particles. (3) Due to the methane hydrate decomposition, the free water molecules increase, which reduces the friction of soil particles

High Glucose-induced VSMC proliferation and migration is associated with decreased PGC-1α expression.

<p>Cultured rat VSMCs were incubated for 48 h in 5.5 mM, 11 mM, 15 mM and 25 mM glucose respectively, Cell growth was determined by counting the number of cells (A) and VSMC migration was determined by a standard wound healing assay (B), PGC-1α expression was determined by real-time RT-PCR by using primers specific for rat PGC-1α and β-actin (C). The bars represent means±S.E.M (n = 6). *P<0.05, **P<0.01, #P<0.001 vs. cells incubated in 5.5 mM glucose. Arterial samples were obtained from the normal and STZ injected rats, the intima and outer and inner tissue layers were removed from arteries. PGC-1α expression was determined by real-time RT-PCR. Data (n = 10) were expressed as means±S.E.M. *P<0.05 vs. normal rats (D).</p

Suppression of PGC-1α abolishes the inhibitory effect of palmitic acid on high glucose-induced VSMC growth and movement.

<p>VSMCs were transfected with siRNA (SI) or the negative control (N), then left stimulated with 15 mM gluoose (HG) in the presence of 0.4 mM palmitic acid (PA) for 48 h. Cell growth was determined by counting the number of cells (A). Migration distance was determined by a standard wound healing assay (B) and by transwell analysis (C). The bars represent means±S.E.M (n = 6). *P<0.05, **P<0.01, #P<0.001 compared with the N+PA+HG group.</p