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PubMed Journals Articles About "Urea" RSS

03:07 EST 15th December 2018 | BioPortfolio

Urea PubMed articles on BioPortfolio. Our PubMed references draw on over 21 million records from the medical literature. Here you can see the latest Urea articles that have been published worldwide.

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Showing "Urea" PubMed Articles 1–25 of 418

Recent Advances in the Electro-Oxidation of Urea for Direct Urea Fuel Cell and Urea Electrolysis.

This paper provides an overview of recent advances in urea electro-oxidation. Urea sources are abundant from human urine, urea-containing wastewater, and industrial urea, thus becoming an attractive option as anodic fuel for the application in direct urea fuel cells (DUFCs). Besides, as a hydrogen-rich chemical fuel, urea can also be electrolyzed to produce hydrogen for energy storage in the near future. The exact mechanisms of urea decomposition are pretty different in alkaline or neutral mediums and are s...


Performance of the 13C-urea breath test for the diagnosis of H. pylori infection using a substrate synthesized in Brazil: A preliminary study.

The 13C-urea breath test is the main non-invasive test for the diagnosis of Helicobacter pylori infection. The availability of this test throughout the country is limited, mainly due to the difficulty in obtaining the labeled isotope from abroad. Recently, researchers from the Nuclear Energy Center in Agriculture at the University of São Paulo (CENA/USP) succeeded in synthesizing 13C-enriched urea for Helicobacter pylori diagnosis. The aim of the study was to compare the performance of the 13C-urea breath ...

Noncovalent Interactions between Tri-Methylamine N-Oxide (TMAO), Urea, and Water.

Trimethylamine N-Oxide (TMAO) and urea are two important osmolytes with their main significance to the biophysical field being in how they uniquely interact with proteins. Urea is a strong protein destabilizing agent, whereas TMAO is known to counteract urea's deleterious effects. The exact mechanisms by which TMAO stabilizes and urea destabilizes folded proteins continue to be debated in the literature. Although recent evidence has suggested that urea binds directly to amino acid side chains to make protei...


Mechanisms associated with the effects of urea on the micellar structure of sodium dodecyl sulphate in aqueous solutions.

We used simulations by Molecular Dynamics to characterize the mechanism whereby the variations in the urea concentration modifies the micellar structure of sodium dodecyl sulfate monomers in water. From a self-assembled micellar system, we observed that increasing urea concentration leads to a decrease in aggregation number. Likewise, when increasing urea concentration, the micelles increase their nonpolar surface exposed to solvent, while the polar surface exposed to solvent decreases. This rearrangement p...

MXene Sorbents for Removal of Urea from Dialysate - a Step Towards the Wearable Artificial Kidney.

The wearable artificial kidney can deliver continuous ambulatory dialysis for more than 3 million patients with end-stage renal disease. However, the efficient removal of urea is a key challenge in miniaturizing the device and making it light and small enough for practical use. Here, we show that two-dimensional titanium carbide (MXene) with the composition of TiCT, where T represents surface termination groups such as -OH, -O-, and -F, can adsorb urea, reaching 99% removal efficiency from aqueous solution ...

Urea changes oocyte competence and gene expression in resultant bovine embryo in vitro.

SummaryNutrition influences the microenvironment in the proximity of oocyte and affects early embryonic development. Elevated blood urea nitrogen, even in healthy dairy cows, is associated with reduced fertility and there is high correlation between blood urea levels and follicular fluid urea levels. Using a docking calculation (in silico), urea showed a favorable binding activity towards the ZP-N domain of ZP3, that of ZP2, and towards the predicted full-length sperm receptor ZP3. Supplementation of oocyte...

Calculating Standard Kt/V during Hemodialysis Based on Urea Mass Removed.

We derived a novel equation for calculating weekly urea standard Kt/V (stdKt/V) during hemodialysis (HD) based on urea mass removed, comparable to the approach during peritoneal dialysis.

Dysregulated Urea Cycle-Associated Signatures Are Tumor Biomarkers.

Urea cycle dysregulation is linked to both poor prognosis and improved response to immunotherapy.

The green and stable dissolving system based on KOH/urea for homogeneous chemical modification of chitosan.

The novel solvent (0.25 M KOH/0.01 M urea alkaline solution) was used to successfully dissolve chitosan without freezing-thawing cycles, for the first time. The results from XRD, FTIR, and CNRM proved that KOH/urea solution could destroy the hydrogen bonds between chitosan chains more efficiently than NaOH/urea solution. The dynamic light scattering, rheology, viscosity and elemental analysis confirmed that the KOH/urea hydrogen-bonded chitosan complex had a better thermal stability at 40 °C, and no ...

Determination of urea with special emphasis on biosensors: A review.

Urea is the major end product of nitrogen metabolism in humans, which is eliminated from the body mainly by the kidneys through urine but is also secreted in body fluids such as blood and saliva. Its level in urine ranges from 7 to 20 mg/dL, which drastically rises under patho-physiological conditions thus providing key information of renal function and diagnosis of various kidney and liver disorders. Increase in urea levels in blood, also referred to as azotemia or uremia. The chronic kidney disease (CKD...

Pd(II)-Catalyzed Cyclization-Oxidation of Urea-Tethered Alkylidenecyclopropanes.

A Pd(OAc)-catalyzed intramolecular oxidative cyclization of urea-tethered alkylidenecyclopropanes with urea as a nitrogen source through a Pd(II)/Pd(IV) catalytic cycle has been presented, giving the corresponding cyclobuta[ b]indoline derivatives in moderate to good yields with a broad substrate scope. The reaction proceeds through a ring expansion of alkylidenecyclopropane along with the nucleophilic attack of nitrogen atom onto the in situ generated palladium carbenoid species as well as an oxidation pro...

Utilization of urea and cyanate in waters overlying and within the Eastern Tropical North Pacific Oxygen Deficient Zone.

In marine oxygen deficient zones (ODZs), which contribute up to half of marine N loss, microbes use nitrogen (N) for assimilatory and dissimilatory processes. Here we examine N utilization above and within the ODZ of the Eastern Tropical North Pacific Ocean, focusing on distribution, uptake, and genes for the utilization of two simple organic N compounds, urea and cyanate. Ammonium, urea, and cyanate concentrations generally peaked in the oxycline while uptake rates were highest in the surface. Within the O...

How Does Aqueous Choline-O-Sulfate Solution Nullify the Action of Urea in Protein Denaturation?

Choline-O-sulfate (COS) acts as a protecting osmolyte in several plants, fungal and bacterial species. Classical molecular dynamics simulation is performed to examine the molecular mechanism by which COS molecules counteract urea-conferred denaturation of S-peptide analogue. The calculations of root mean squared deviation, the radius of gyration of Cα atom and solvent accessible surface area of the peptide heavy atoms imply that the 4-12 residues of the peptide in pure water remain in helical conformation ...

Salivary creatinine and urea are higher in an experimental model of acute but not chronic renal disease.

Plasma creatinine and urea are commonly used markers of kidney function in both acute and chronic renal failure. The needed repeated blood collection is associated with pain, stress and might lead to infections. Saliva has the potential to be a non-invasive alternative diagnostic fluid. The use of saliva in clinical practice is limited, since many factors affect the concentration of salivary biomarkers. The aim of our study was to analyze salivary creatinine and urea in the animal models of acute and chroni...

The effects of urea and caprolactam on the molecular mechanisms and elastic modulus of polyvinyl alcohol (PVA): A molecular dynamics simulation study.

The interaction mechanism in modified poly(vinyl alcohol) (PVA) with urea and caprolactam were investigated by molecular dynamics (MD) simulation method. Five simulation models of PVA composites with different plasticizer content were constructed to investigate the variation of the intermolecular interaction as well as its effect on the elastic modulus of PVA. The results indicated the interaction between polar functional groups and surrounding hydrogen atoms in PVA was hydrogen bonds. With the increasing o...

A slow release brown coal-urea fertiliser reduced gaseous N loss from soil and increased silver beet yield and N uptake.

Increasing crop yield and fertiliser nitrogen (N)-use efficiency is important for productive agricultural systems with a reduced environmental footprint. The aim of this study was to assess the effect of slow release brown coal-urea (BCU) fertiliser on the gaseous N losses, biomass yield and N uptake by silver beet (Beta vulgaris L.) compared to commercial urea. Two soils were amended with urea, BCU 1 (22% N) or BCU 2 (17% N) as N-fertiliser at the rate of 50 or 100 kg N ha. Five gas sampling periods ...

Ligand Isomerism in Coordination Cages.

Complexation reactions of palladium(II) nitrate with a set of 3-pyridyl appended nonchelating bidentate ligands possessing regioisomeric phenylene-diurea functionalities as spacers were carried out. The ligands utilized in this study are 1,1'-(1,2-phenylene)bis(3-(pyridin-3-yl)urea), L1; 1,1'-(1,3-phenylene)bis(3-(pyridin-3-yl)urea), L2; and 1,1'-(1,4-phenylene)bis(3-(pyridin-3-yl)urea), L3. The complexation reactions of the ligands (L1, L2, and L3) with palladium(II) produced single discrete isomeric cages...

Urea-modulated UT-B urea transporter internalization is clathrin- and caveolae-dependent in infantile hemangioma-derived vascular endothelial cells.

The aim of this study was to investigate the manner of urea-modulated UT-B urea transporter (UT) internalization in infantile hemangioma-derived vascular endothelial cells (HemECs). The immunohistochemistry assay was performed to identify infancy hemangioma-derived endothelial cell line (XPTS-1) cells. Cell toxicity was detected with the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. Quantitative real-time polymerase chain reaction and Western blot analysis were measured to analy...

Urea derivative catalyzed enantioselective aldol reaction of isatins with ketones.

Urea derivative has been used to catalyze the asymmetric aldol reaction of isatins with ketones. The resulting 3-alkyl-3-hydroxy-indolin-2-ones products were obtained in good yields (70%-94%) with high enantioselectivities (up to 87%ee).

Effects of pearl millet silage ammoniation with urea on carcass and meat quality of lambs.

This study aimed to evaluate the effect of pearl millet silage ammoniated with urea on lamb carcass characteristics and meat quality. Thirty-two noncastrated crossbred lambs at 4-5 months of age, with an average initial body weight of 17.39 ± 2.16 kg, were distributed into four treatments in a randomized block experimental design with eight animals per treatment. Experimental diets were composed of pearl millet silage ammoniated with four levels of urea (0%, 2%, 4% and 6%, on dry matter basis (DM). Car...

Effect of urine compounds on the electrochemical oxidation of urea using a nickel cobaltite catalyst: An electroanalytical and spectroscopic investigation.

Cyclic voltammetry (CV) and in-situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy were used to investigate the effect of major urine compounds on the electrooxidation activity of urea using a nickel cobaltite (NiCo2O4) catalyst. As a substrate, carbon paper exhibited better benchmark potential and current values compared to stainless steel and fluorine-doped tin oxide glass, which was attributed to its greater active surface area per electrode geometric area. CV analysis of...

Urea cycle disorders in India: clinical course, biochemical and genetic investigations, and prenatal testing.

Urea cycle disorders (UCDs) are inherited metabolic disorders that present with hyperammonemia, and cause significant mortality and morbidity in infants and children. These disorders are not well reported in the Indian population, due to lack of a thorough study of the clinical and molecular profile.

The Uncoupled Assimilation of Carbon and Nitrogen from Urea and Glycine by the Bloom-forming Dinoflagellate Prorocentrum minimum.

The spread of harmful dinoflagellate blooms has been linked to the increasing availability of nitrogen, including its dissolved organic forms. The relationships between organic and inorganic nutrient uptake by dinoflagellates are not completely understood; moreover, it is not clear whether organic substances are used exclusively as nitrogen or also as carbon sources. We used laboratory culture experiments to investigate the concurrent uptake of glycine and nitrate by Prorocentrum minimum and estimate a role...

Effect of supplemental dietary slow-release urea on growth performance and physiological status of dairy heifers.

We examined the effect of supplemental dietary slow-release urea on the growth performance and physiological status of 16 dairy Holstein heifers (10 months of age, 322 ± 10 kg). The heifers were offered a formulated isocaloric and isonitrogenous 70:30 roughage : concentrate ration and were assigned randomly to one of four levels of slow-release urea supplementation (0% [U ], 1% [U ], 1.5% [U ] and 2% [U ] dry matter [DM]). The total study lasted 95 days, which included a 20 days adaptation period. ...

Corn grain yield and 15N-fertilizer recovery as a function of urea sidedress timing.

Best fertilizer management practices such as adopting the right N sidedress timing can reduce N losses by volatilization, thus, raising N-fertilizer recovery and grain yield. To evaluate ammonia (N-NH3 ) losses, N-fertilizer recovery and grain yield as a function of urea sidedress timing in corn, a field study was conducted during the 2011-2012 and 2012-2013 growing seasons, adopting a complete randomized block design with four replications. Treatments consisted of urea sidedress timing (140 kg N ha-1) at V...


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