background: like several other parasites, teladorsagia circumcincta secretes or excretes urea, but nei-ther the rate of efflux nor the possible metabolic sources of the urea has been considered. methods: parasites were maintained by passage through sheep. urea efflux was measured using phe-nol/hypochlorite after treatment with urea aminohydrolase. the kinetics of creatine amidinohy-drolase and ...

wear is a complicated phenomenon caused by the relative movement of two contacting surfaces compressed together by a normal force. prediction of the wear, in most cases, requires various experiments and microstructural characterization of the contacting surfaces. mathematical models based on physical concepts could provide considerable help in understanding the physical behavior and hence the p...

Supramolecular hydrogels are useful in many areas such as cell culturing, catalysis, sensing, tissue engineering, drug delivery, environmental remediation and optoelectronics. The gels need specific properties for each application. arise from a fibrous network that forms the matrix. A common method to prepare is use pH change. Most methods result sudden jump often lead hard reproduce control. u...

Helicobacter pylori resists gastric acidity by modulating the proton-gated urea channel UreI, allowing for pH(out)-dependent regulation of urea access to intrabacterial urease. We employed pH- and Ca(2+)-sensitive fluorescent dyes and confocal microscopy to determine the location, rate, and magnitude of pH changes in an H. pylori-AGS cell coculture model, comparing wild-type bacteria with nonpo...

Urea production rate (Ra) is commonly measured using a primed continuous tracer urea infusion, but the accuracy of this method has not been clearly established in humans. We used intravenous infusions of unlabeled urea to assess the accuracy of this technique in normal, postabsorptive men under the following four different conditions: 1) tracer [13C]urea was infused under basal conditions for 1...

Background. Dialysis dose is commonly defined as a clearance scaled to some measure of body size, but the toxicity of uraemic solutes is probably associated more to their concentrations than to their clearance. Methods. 619 dialysis sessions of 35 patients were modified by computer simulations targeting a constant urea clearance or a constant urea concentration. Results. Urea generation rate G ...

Second-generation self-assembling bis-urea macrocycles were designed that form columnar structures in the solid state. The new macrocycles were constructed from more flexible building blocks yielding greater solubility and a more efficient synthesis. In addition, heteroatoms in the form of ether oxygens were incorporated in the walls of the macrocycles to provide additional recognition sites fo...

When behavioral avoidance cannot prevent an animal from being exposed to novel environmental toxins, physiological mechanisms must cope with the toxin and its effects. We are investigating the basis of urea tolerance in populations of Drosophila melanogaster that have been selected to survive and develop in food containing 300 mmol l(-1) urea. Previous research has demonstrated that the urea-se...