Metabolism of polyamines and oxidative stress in the brain of cholestatic rats

In a recently published article in “Amino Acids” it was shown that obstructive jaundice of 9 days’ duration in rats induces significant alterations of polyamines’ metabolism in the brain, which might play an important pathogenetic role in cholestatic brain injury. The authors proposed that alterations of polyamines in cholestatic brain might induce neuronal toxicity through a mechanism that implicates the production of reactive oxygen species and oxidative stress, although this parameter was not evaluated in their study. This hypothesis is supported by our recent findings on brain oxidative status in rats with obstructive jaundice of 10 days’ duration. Potential interrelations of the two studies’ findings are discussed in this commentary.     

The Effect of Organic and Metal Oxide Interfacial layers on the Performance of Inverted Organic Photovoltaics

We study the origin of the improvement of the power conversion efficiency (PCE) of inverted organic solar cells when an interfacial insulating organic layer of polyoxyethylene tridecyl ether (PTE) is introduced between the indium tin oxide (ITO) bottom electrode and the TiO_x interfacial layer. XPS and UPS measurements are used to investigate the energy level alignment at the interfaces within the ITO/TiO_x and ITO/PTE/TiO_x structures and to identify any effects due to chemical interaction and interfacial dipoles. Scanning electron microscopy studies show that the surface structure of the TiO_x layer is affected, when it is coated on top of the PTE layer. Surface contact angle measurements show that the incorporated interfacial layer of PTE is more hydrophilic than ITO and thus PTE modified TiO_x becomes more hydrophilic. This, in combination with the surface gaps of the PTE interfacial layer, is likely to lead to changed wetting and hydrolysis properties of TiO_x when coated on ITO/PTE than on ITO alone. The different TiO_x layer quality is reflected in improved electron selectivity, leading to enhanced fill factor, reduced parasitic resistance effects and higher power conversion efficiency for inverted solar cells with a PTE interfacial layer between ITO and TiO_x.     

Reversine ameliorates hallmarks of cellular senescence in human skeletal myoblasts via reactivation of autophagy

Cellular senescence leads to the depletion of myogenic progenitors and decreased regenerative capacity. We show that the small molecule 2,6-disubstituted purine, reversine, can improve some well-known hallmarks of cellular aging in senescent myoblast cells. Reversine reactivated autophagy and insulin signaling pathway via upregulation of Adenosine Monophosphate-activated protein kinase (AMPK) and Akt2, restoring insulin sensitivity and glucose uptake in senescent cells. Reversine also restored the loss of connectivity of glycolysis to the TCA cycle, thus restoring dysfunctional mitochondria and the impaired myogenic differentiation potential of senescent myoblasts. Altogether, our data suggest that cellular senescence can be reversed by treatment with a single small molecule without employing genetic reprogramming technologies.     

A Triple-Arginine Motif in the Amino-Terminal Domain and Oligomerization Are Required for HIV-1 Inhibition by Human MX2

We have employed molecular genetic approaches to understand the domain organization of the HIV-1 resistance factor myxovirus resistance 2 (MX2). First, we describe an essential triple-arginine motif in the amino-terminal domain. Second, we demonstrate that this 91-residue domain mediates antiviral activity when appended to heterologous proteins, and we provide genetic evidence that protein oligomerization is required for MX2 function. These insights will facilitate future work aiming to elucidate MX2''s mechanism of action.