Immunoglobulin A in saliva of children: age dependence and effect of respiratory tract diseases

Immunoglobulin A (IgA) plays an essential role in the local defence mechanism and is part of the immunologic system. It is transported to the endothelial surface either as a monomer or as a dimer of two molecules of IgA connected by a j-chain and attached to a secretory component. The aim of the present study was to assess the relation of salivary IgA to the age of children and to assess a possible influence by acute and chronic respiratory diseases. IgA was measured in the saliva of altogether 230 children by means of radial immunodiffusion (LC-IgA Partigen, Behring) following a standardised protocol. Relation to age was measured in 159 healthy children aged one month to 15 years. The median of IgA was 36 mg/l with a range of 3.5-291 mg/l. There was no statistically significant relationship between salivary IgA and the age of the children. Median IgA in the saliva of children without any respiratory disorders (n = 169) was 36 mg/l (3.5-291 mg/l), of children with acute respiratory diseases (n = 33) 51 mg/l (3.5-257 mg/l) and of children with chronic respiratory diseases (n = 28) 47 mg/l (3.5-165 mg/l). There was no statistically significant difference between these three groups. In conclusion, the results of this study show that IgA in the saliva of children may not be related to age or influenced by acute or chronic respiratory diseases.     

Continuous measurement of visible persistence.

In the synchrony judgment paradigm, Ss judge whether a click precedes or follows the onset of a light flash and, on other trials, whether or not a click precedes light termination. The interclick interval defines the duration of visible persistence. An elaboration of this method was developed that consisted of 2 phases: In Phase 1, the luminance of a reference stimulus was psychophysically matched to the peak brightness of the test flash. Five luminance values between .1 and 1.0 of the reference stimulus were used subsequently. In Phase 2, a random 1 of the 5 reference stimuli, a test flash, and a click were presented; the Ss judged whether the click occurred before or after the brightness of test flash reached the reference value (on onset trials) or decayed below it (on termination trials). This method was validated on 3 male graduate students with test stimuli whose luminance rose and decayed slowly in time, and then was used to trace out the precise subjective rise and decay (temporal brightness response function) of brief flashes. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hydrocarbon gases produced during in vitro peroxidation of polyunsaturated fatty acids and decomposition of preformed hydroperoxides

Hydrocarbon gases have been used previously as an index of lipid peroxidation in vivo and in vitro. In vitro experiments are reported on the formation of hydrocarbon gases from peroxidizing ω-3 and ω-6 fatty acids. Hydrocarbon gases were not related during a 20-hr peroxidation phase but were released following the decomposition of hydroperoxides by addition of excess ascorbic acid. The major hydrocarbon gas products in iron, copper, or hematin catalyzed peroxidation systems were ethane or ethylene from linolenic acid, and pentane from linoleic acid and arachidonic acid. Calculations of the ratios of hydrocarbon gases formed were based on fatty acid decrease and/or change in diene conjugation and peroxide values. Depending on the fatty acid, catalyst, and calculation basis used, pentane formation was a high as 1.3 mol %, ethanol 4.3 mol %, and ethylene 10.6 mol %.     

Computational materials design: A perspective for atomistic approaches

Summary Present theoretical and computational approaches, combined with the impressive advances in computer hardware and software, open the possibility for materials design from first principles. This article presents a perspective on the relevant developments in computational chemistry, solid state physics and statistical mechanics and it assesses the merits and limitations of Hartree-Fock, density functional, semiempirical and force field approaches in terms of six criteria: capability, generality, accuracy, accessible system size, accessible time scales and computational efficiency. Functional materials for microelectronic, optical and magnetic applications currently present better opportunities for first-principles approaches than structural materials, where atomistic approaches, despite some encouraging results, are still far from capturing the full complexity of the dynamics involved in mechanical, thermal, diffusive and corrosive behavior.