Role of nitric oxide in cyclosporine A-induced hypertension

Cyclosporine A (CsA) is an immunosuppressive agent that also causes hypertension. The effect of CsA on vascular responses was determined in Sprague-Dawley rats and isolated rat aortic rings. Male rats weighing 250 to 300 g were given either CsA (25 mg. kg-1. d-1) in olive oil or vehicle by intraperitoneal injection for 7 days. CsA administration produced a 42% increase (P<0.001) in mean arterial pressure (MAP) that reached a plateau after 3 days. Conversely, the levels of both nitrate/nitrite, metabolites of nitric oxide (NO), and cGMP, which mediates NO action, decreased by 50% (P<0.001) and 35% (P<0.001), respectively, in the urine. Thoracic aortic rings from rats treated with CsA and precontracted with endothelin (10(-9) mol/L) showed a 35% increase (P<0.001) in tension, whereas endothelium-dependent relaxation induced by acetylcholine (ACh, 10(-9) mol/L) was inhibited 65% (P<0.001) compared with that in untreated rats. This response was similar to that of endothelium-denuded aortic rings from untreated rats in which ACh-induced relaxation was completely abolished (P<0.001), but relaxation induced by S-nitroso-N-acetylpenicillamine (SNAP, 10(-8) mol/L) was unaffected (P<0.001). ACh-induced formation of both nitrate/nitrite and cGMP by both denuded and CsA-treated aortic rings was inhibited 95% (P<0.001) and 65% (P<0.001), respectively, compared with intact aortic rings. The effects of CsA were reversed both in vivo and in vitro by pretreatment with L-arginine (10 mg. kg-1. d-1 IP), the precursor of NO. There were no changes in MAP and tension in rats treated with L-arginine alone. In summary, CsA inhibits endothelial NO activity, with resulting increases in MAP and tension, and this inhibition can be overcome by parenteral administration of L-arginine.     

Improved food quality,quantity and security among Kenyan orphans and vulnerable children: associations with participation in a multisectoral community-based program,age, gender,and sexual risk

The present study evaluates factors associated with improved food quantity, quality and diversity among participants in a 3-year multisectoral program targeting sibling families of orphans and vulnerable children in rural Kenya. This cross-sectional study evaluates food adequacy and diversity using the World Food Programme’s Food Consumption Score, food access over the previous year, and food dependence on outside-household resources among 1060 families of orphan or vulnerable siblings. The primary comparison group was program-enrolled households who had not yet received any program inputs. Mixed effects logistic models were used to assess the association of food quantity, quality and security with program participation, program inputs and respondent characteristics. Increased time in the program was significantly associated with improved food quantity, quality and security. Other covariates significantly predicting improved food quantity, quality and security included using program-funds to cultivate small-holder farms, increased monthly income, self-efficacy and the number of partners in previous year. After adjusting for monthly income and other covariates, duration of program participation remained a significant predictor of improved food consumption, quality and security. The study presents a unique community-based intervention, hybridizing insights from multiple disciplines that warrants further study to improve the food quantity, quality and security of orphans and vulnerable children across sub-Saharan Africa.     

Absorption and desorption properties of fine lightweight aggregate for application to internally cured concrete mixtures

Recently, substantial interest has developed in using fine lightweight aggregate for internal curing in concrete. Mixture proportion development for these mixtures requires the specific gravity, water absorption, and water desorption characteristics of the aggregate. This paper presents results from a recent study in which the properties of commercially available expanded shale, clay and slate lightweight aggregates (LWA’s) were measured. This research measured the time-dependent water absorption response for the lightweight aggregate. The results indicate that a wide range of 24 h water absorption values exist for commonly used fine lightweight aggregates (e.g., absorption between 6% and 31%). Desorption was measured and it was found that between 85% and 98% of the 24 h absorbed water is released at humidities greater than 93%. These properties can be normalized so that they can be efficiently used in proportioning concrete for internal curing. Normalized plots of absorption and desorption demonstrate benefits for a single function that describes a large class of expanded shale, clay, and slate aggregate for use in internal curing.     

Towards Dynamic, Tunable, and Nonlinear Metamaterials via Near Field Interactions: A Review

Metamaterials research continues to bear fruit in the form of novel devices and optics across the electromagnetic spectrum. This is especially true in the gigahertz, terahertz, and near infrared frequencies. Metamaterials also continue to be one of the fastest growing subdisciplines of anisotropy research, with most notable metamaterial advances based on inherently anisotropic designs. Despite significant progress, many challenges remain before fully dynamic, broad bandwidth, and nonlinear metamaterial devices become truly viable. We review the study of near field interactions, or coupling, in metamaterials with a focus on how manipulation of interactions in metamaterials has helped overcome some of the largest obstacles toward tunable metamaterials, broad bandwidth metamaterials, nonlinear metamaterials, and metamaterial experimental techniques.     

Wet oxidation of stainless steels: New insights into hydrogen ingress

It is well established that hydrogen derived from water vapor can penetrate oxidizing alloys with detrimental effect. However, the complexities of tracking hydrogen in these materials have prevented the direct profiling of hydrogen ingress needed to understand these phenomena. Here we report hydrogen profiles in industrially-relevant alumina- and chromia-forming steels correlated with the local oxide-metal nano/microstructure by use of SIMS D₂O tracer studies and experimental protocols to optimize D retention. The D profiles unexpectedly varied markedly among the alloys examined, which indicates mechanistic complexity but also the potential to mitigate detrimental water vapor effects by manipulation of alloy chemistry.     

The development of metallic nuclear fuels for transmutation applications: Materials challenges

Metallic alloys show great potential to serve as transmutation fuels that could be used to burn long-lived and high-heat-producing minor actinides and fission products in nuclear reactors as part of the Global Nuclear Energy Partnership program. To implement these fuels, work is ongoing to develop fuel fabrication processes, characterize alloy microstructures, measure fuel properties, determine the compatibility of fuel and cladding alloys, and understand the performance of the fuel alloys during irradiation.     

Boron Segregation to Grain Boundaries and Improved Ductility in Pt + 30 Wt Pct Rh + 8WtPctW

Boron additions of up to 75 wt ppm have been observed to improve the room temperature strength and ductility of a Pt + 30 wt pct Rh + 8 wt pct W alloy. Alloys without boron fail intergranularly, and those with 75 wt ppm boron added fail in a mixed intergranular-transgranular mode. Auger electron spectroscopy on intergranular fracture surfaces indicated that boron segregates strongly to grain boundaries in the boron doped alloys. Transmission electron microscopy of alloys with and without boron indicated that both were free of internal precipitates. The observed improvements in strength and ductility appear to be related to boron enrichment within a few atomic distances of the grain boundary.     

ATS-6 Spacecraft Surface Treatment for the Control of Electrical Discharges

The Applications Technology Statellite-6 (ATS-6) has successfully withstood repeated entrances into and exits from occult in a period centered on the 1974 autumn equinox, during which it was subject to potential changes as hikh as 11 000 volts based on onboard measurements. Much of the outer surface of the spacecraft is an insulator, dictated by thermal control design. Consequently, special measures were required to protect the spacecraft, and especially its commmand receiving system, from electrical dischargesp whose accompanying fields could destroy sensitive receiving circuits. This paper describes the thermal blanket grounding criteria applied to prevent undesired discharge effects.     

Abschätzung der porenstruktur poröser elektroden aus impedanzmessungen

The variation of the pore impedance Z with the frequency ω has been examined for various geometries of a single pore and the results applied to the case of porous electrode. From the impedance curve and by comparison with the values calculated for electric models the average pore structure can be estimated.     

Phagocytosis and biodegradation of short-chain poly [(R)-3-hydroxybutyric acid] particles in macrophage cell line

The biocompatibility and the degradation mechanisms of block co-polyurethanes containing crystallizable telechelic poly [(R)-3-hydroxybutyric acid] (PHB) segments have found recently growing interest for the possible biomedical applications of these new materials. The random hydrolytic cleavage of the amorphous part of these polymers might result, in vivo, in the production of small crystalline particles of low molecular weight PHB that could then undergo phagocytosis and biodegradation inside phagosomes. To test this possibility, a fluorescent-labelled PHB segment was synthesized, precipitated in the form of crystalline particles, and used for an in vitro investigation of its interaction with macrophage cell line. Light and fluorescence microscopy performed in the present study clearly show that the fluorescent particles are well internalized in phagosomes already after 1 h of incubation. The number of phagocytized particles decreases notably after 8 days of incubation.A quantitative determination of the time dependence of the phagocytosis was obtained through laser cytometry and fluorescence-activated cell sorting (FACS). Fluorescence spectroscopy and high-performance liquid chromatography (HPLC) analysis of extracts of cell supernatants revealed the presence of supposed degradation products of PHB after 8 days of incubation, suggesting that macrophages could degrade low molecular weight PHB.