Cytochrome P460 Cofactor Maturation Involves a Peroxide- Dependent Post-Translational Modification

Cytochrome P460s are heme enzymes that oxidize hydroxylamine to nitrous oxide as part of the biogeochemical nitrogen cycle. They bear unique “heme P460” cofactors that are cross-linked to their host polypeptides by a post-translationally modified lysine residue. Wild-type N. europaea cytochrome P460 may be isolated as a cross-link deficient proenzyme following anaerobic overexpression in E. coli. When treated with peroxide, This proenzyme undergoes complete maturation to active enzyme with spectroscopic properties that match wild-type cyt P460. Together, these data indicate that the cofactor is primed to undergo this covalent modification by virtue of the protein fold. A putative mechanism analogous to that used by heme oxygenases to degrade hemes is proposed.

Microcirculation and Macrocirculation in Hypertension: A Dangerous Cross-Link?

Microcirculation and macrocirculation are tightly interconnected into a dangerous cross-link in hypertension. Small artery damage includes functional (vasoconstriction, impaired vasodilatation) and structural abnormalities (mostly inward eutrophic remodeling). These abnormalities are major determinants of the increase in total peripheral resistance and mean blood pressure (BP) in primary hypertension, which in the long term induces large artery stiffening. In turn, large artery stiffening increases central systolic and pulse pressures, which are further augmented by wave reflection in response to the structural alterations in small resistance arteries. Finally, transmission of high BP and flow pulsatility to small resistance arteries further induces functional and structural abnormalities, thus leading to increased total peripheral resistance and mean BP, thus perpetuating the vicious circle. Hyperpulsatility, in addition to higher mean BP, exaggerates cardiac, brain, and kidney damages and leads to cardiovascular, cerebral, and renal complications. The dangerous cross-link between micro and macrocirculation can be reversed into a virtuous one by ACE (angiotensin-converting enzyme) inhibitors, sartans, and calcium channel blockers. These three pharmacological classes are more potent than β-blockers and diuretics for reducing arterial stiffness and small artery remodeling. The same ranking was observed for their effectiveness at reducing left ventricular hypertrophy, preserving glomerular filtration rate, and preventing dementia, suggesting that they can act beyond brachial BP reduction, by breaking the micro/macrocirculation vicious circle.

Effect of the cure time on the Mechanical Properties of Silicone Rubber used as Socket Liners

This work is focused on the upper part of the prosthesis which is called a socket, it is in contact connect with the amputated part. The shear force between skin and socket, local pressure, sweating, and bacteria generation, all lead to skin inflammation and a bad smell. Consequently, the prosthesis became uncomfortable for a patient. To address this issue silicone rubber liners is proposed to use because it can absorb moisture, stress distribution, and anti-bacterial. The curing time and temperature are important factors for determining crosslink density, from the results obtained, can be noticed that, the cross-link density can greatly affect the silicone rubber properties, it can have a direct effect on the tensile strength, modulus of elasticity, percentage of elongation as well as the water absorption, and the cure time (15 min.) shoes the best resalt. As a result, using it making the prosthesis more comfortable and acceptable to the patient. In this paper, the effect of cure time on physical properties was studied.

Gel Polymer Electrolyte Based on Methyl Methacrylate for Lithium-Sulfur Batteries

Lithium-sulfur batteries are next-generation battery systems with low cost and high specific energy. However, it is necessary to solve several deficiencies of these batteries such as shuttle effect, and gel polymer electrolyte is a great candidate. These perspective materials can be used as a replacement for liquid electrolytes, and at the same time, they can help to solve the problems of lithium-sulfur batteries. In this work, gel polymer electrolyte (GPE) based on methyl methacrylate was prepared by cross-linking strategy. As cross-link ethylene glycol dimethacrylate (EDMA) was used. Prepared gel with a high electric conductivity was testing in the lithium-sulfur cell (Li/GPE/S). The electrochemical performance of the cell was studied.