Dietary L-arginine in renal disease

The amino acid L-arginine is a substrate for at least three products involved extensively in tissue injury and fibrosis. L-arginine is metabolized to L-proline, a major constituent of the collagen that makes up fibrotic extracellular matrix. L-arginine is a precursor for polyamines, which are required for proliferative responses characteristic of many renal disease. L-arginine is also the sole substrate for generation of nitric oxide (NO) which, produced in large quantities by macrophages, has been implicated in tissue injury. On the other hand, NO produced in small quantities by endothelium is a critical vasodilator. Given the importance of elevated intraglomerular pressure in renal injury, it is perhaps not surprising that dietary L-arginine supplementation increase NO generation and is beneficial in reducing intraglomerular pressure and subsequent disease. Other data, based on the therapeutic effects of low protein diets, have suggested that L-arginine restriction limits NO-mediated glomerular injury and greatly reduces matrix accumulation, consistent with the idea that limitation of substrate effectively diminishes injurious NO levels, polyamine synthesis, and collagen production.     

A single-step method for determination of the specific radioactivity of lipids

The use of a liquid scintillation counter to measure both the mass and the radioactivity content of charred¹⁴C-labeled lipid bands from thin layer chromatoplates has been evaluated. Following lipid mass determination from a measurement of the external standard channels ratio, a suitable choice of counting parameters enabled a reproducible and efficient¹⁴C count to be obtained over virtually the whole range of lipid concentrations tested. Although the charring procedure resulted in some loss of radioactivity, the efficiency of counting remained high enough for accurate dpm measurements.     

Comparison of reciprocal inhibition, psychotherapy, and waiting list control for phobic children.

Randomly assigned 67 phobic 6-15 yr. olds to a 2 * 3 factorial, repeated-measures, covariate design which included 2 male therapists and 3 time-limited treatments: reciprocal inhibition, psychotherapy, and waiting list control. Following 24 sessions or 3-mo wait and at 6-wk follow-up, Ss were reassessed by an independent evaluator and by parents. Results indicate a significant effect due to time and S's age. Clinical evaluation, using initial scores as the covariate, showed no effects of treatment or therapist. Parents reported treatment effects for both target fear and general fear behavior. Therapies were equally efficient, and all treatment effects were achieved with Ss aged 6-10. (48 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of current-voltage diagrams in locating peak energy barriers in cell membranes

The current-voltage relations obtained by integrating the Nernst-Planck equations for a variety of energy profiles are obtained. A simple and approximate method for comparing these relations is described. The method is based on using a linearized transform of current-voltage relations for an Eyring single barrier model. A parameter, gamma, related to the location of the single barrier in the Eyring model, and to the shape of the barrier in other models, is readily obtained from the slopes of the linearized relations. It is then a simple matter to determine whether a given current-voltage relation allows discrimination between any particular energy profiles. The results show that the equivalent Eyring model does not always place the peak energy barrier in the same position as other models and that quite large errors in the assignment of position may be made if such a model is used. The results are also used to test the ability of some experimental current-voltage diagrams to discriminate between various energy profiles.     

A numerical method for treating indentation problems

Summary Abel transforms are used to simplify the equations describing the deformation of an elastic medium by a rigid indentor with a circular cross-section. The equations derived constitute a convenient starting point for the numerical solution of such problems. As a particular example the case of a parabolic rough punch is treated.     

Diazepam treatment of socially isolated monkeys

Four rhesus monkeys were reared for the first eight months of life in total social isolation. One animal died during this period; the three remaining subjects were treated with diazepam in an isolation chamber, in their home cages, and in a playroom testing situation. Diazepam significantly decreased the self-disturbance behaviors of two subjects, and there was even the appearance of some social behaviors, although they were limited and not of the same quality as in nonisolated subjects. The authors discuss the implications of the data for understanding the significance of the social isolation syndrome in monkeys as a model for human psychoses.     

Fatigue of Mg3Cd

The fatigue behaviour of Mg₃Cd has been studied under stress-cycling conditions for both single crystal and polycrystalline specimens, in the ordered and disordered state, at room temperature. The results indicate that the polycrystalline material has very poor fatigue resistance for both states of order and that failure probably initiates in basal slip bands. The single crystal results are not directly consistent with earlier work on monotonic deformation, but show fatigue failures at lower stresses than expected.