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Notes: Background. Enzyme linked immunosorbent assay (ELISA) evaluation of oral fluid immunoglobulin G (IgG) antibodies to Helicobacter pylori is a unique approach for both epidemiological studies and the diagnosis of infection, especially in children. The use of oral fluid sampling to evaluate specific H. pylori IgG antibodies has advantages over serum, including reduced biohazard risk and noninvasive collection. Oral fluid sampling is fast and involves minimal patient discomfort. Since children facilitate transmission of H. pylori infection, a simple, accurate, noninvasive diagnostic test is necessary for large epidemiologic studies. The aim of our study was to evaluate a new oral fluid ELISA for detection of IgG antibodies to H. pylori in children.Materials and methods. We compared this new oral fluid ELISA with the HM-CAPTM serum ELISA and gastric biopsy histology using 779 oral fluid samples from children collected at 11 clinical sites across the United States. This cohort included 315 children symptomatic for abdominal pain and 464 asymptomatic. All samples were evaluated in a double blind manner. The oral fluid ELISA demonstrated a sensitivity of 76.2% and a specificity of 94.0% in children 2 months old to 201/2 years, as compared with the HM-CAPTM serologic assay. The assay’s sensitivity improved to 81.3% in children aged 5 or greater and the specificity remained at 94.0%. When compared with gastric biopsy histology in the same age group, the oral fluid ELISA demonstrated a sensitivity of 71.7% and a specificity of 90.4%.Results. This new oral fluid ELISA is moderately sensitive and offers a very specific method for detecting H. pylori infection in older children, but it is of little value in children under the age of 5 years.Conclusions. Overall, we conclude that this oral fluid ELISA does not appear to be a helpful clinical tool for the diagnosis of H. pylori infection in children.

Notes: We present a new method of characterizing the void structures of soils from water retention curves as the primary source of data. The method avoids the problems of other current approaches, which use smoothing curves and can miss the subtleties of soil structure, and usually ignore the shielding of large pores by the small connecting throats surrounding them. In the new method, software we have named ‘Pore-Cor’ is used to generate simple three-dimensional networks of voids that have the same water retention characteristics and porosities as the soils. To find the geometry of the required networks, we have introduced a Boltzmann-annealed simplex which works in four parametric and three Boolean dimensions of parameter space. Also, a more robust measure of the difference between the experimental and simulated water retention curves has been developed. The method is applied to water retention curves for a wide range of English and Welsh soils, both experimental and generated from a pedotransfer function. The resulting simulated void structures have void sizes that change as expected across the soil texture diagram, have different structures as highlighted by the locations of retained water, but have connectivities (number of connecting throats per pore) that vary little. A wide range of other calculations of wetting and non-wetting fluid transport properties, and calculations of the behaviour of fluid-borne pollutants, are now possible. The main bar to further progress is a lack of sufficiently accurate and comprehensive data for water retention, and for saturated and unsaturated hydraulic conductivity.

Notes: —The effect of 1-hydroxy-3-aminopyrrolidone-2(HA-966), a CNS depressant, was studied on the metabolism of [14C]glucose and [3H]acetate in the brain in mice. HA-966 had a marked effect on glucose metabolism. The conversion of glucose carbon into amino acids associated with the tricarboxylic acid cycle (‘cycle’) was severely reduced, while the concentration of brain glucose was approximately doubled. Relative to the specific radioactivity of glucose in the brain, the specific radioactivity of alanine was 60–70 per cent of the control, indicating a reduction in the rate of glycolysis, and those of the‘cycle’amino acids were also lowered. A reduction in‘cycle’flux of 30–35 per cent was estimated. It was established that the depressed glucose utilization flux was not due to either impaired uptake of glucose from blood to brain or to hypothermia. In contrast to [14C]glucose, there was no change in the labelling of the amino acid fraction from [3H]acetate, which is preferentially metabolized in the 'small’compartment believed to be associated with glia. Thus it seems that CNS depression caused by HA-966 resulted in a selective decrease in energy production in the‘large’metabolic compartment where glucose is oxidized preferentially and which is believed to be associated with neuronal structures.The results also suggested that communication between the metabolic compartments mediated via glutamine and GABA was reduced, since the labelling from [3H]acetate of glutamine was increased and that of GABA decreased by HA-966.

Notes: Abstract— Thiamine deficiency produced by administration of pyrithiamine to rats maintained on a thiamine-deficient diet resulted in a marked disturbance in amino acid and glucose levels of the brain.In the two pyrithiamine-treated groups of rats (Expt. A and Expt. B) there was a significant decrease in the levels of glutamate (23%, 9%) and aspartate (42%, 57%), and an increase in the levels of glycine (26%, 27%) in the brain, irrespective of whether the animals showed signs of paralysis (Expt. A) or not (Expt. B). as a result of thiamine deficiency. A significant decrease in the levels of γ-aminobutyrate (22%) and serine (28%) in the brain was also observed in those pyrithiamine-treated rats which showed signs of paralysis (Expt. A). Threonine content increased by 57% in Expt. A and 40% in Expt. B in the brain of pyrithiamine-treated rats, but these changes were not statistically significant.The utilization of [U-14C]glucose into amino acids decreased and accumulation of glucose and [U-14C]glucose increased significantly in the brain after injection of [U-14C]glucose to pyrithiamine-treated rats which showed abnormal neurological symptoms (Expt. A). The decrease in 14C-content of amino acids was due to decreased conversion of [U-14C]glucose into alanine, glutamate, glutamine, aspartate and γ-aminobutyrate. The flux of [14C]glutamate into glutamine and γ-aminobutyrate also decreased significantly only in the brain of animals paralysed on treatment with pyrithiamine.The decrease in the labelling of, amino acids was attributed to a decrease in the activities of pyruvate dehydrogenase and α-oxoglutarate dehydrogenase in the brain of pyrithiamine-treated rats. The measurement of specific radioactivity of glucose, glucose-6-phosphate and lactate also indicated a decrease in the activities of glycolytic enzymes in the brain of pyrithiamine-treated animals in Expt. A only. It was suggested that an alteration in the rate of oxidation in vivo of pyruvate in the brain of thiamine-deficient rats is controlled by the glycolytic enzymes, probably at the hexokinase level.The lack of neurotoxic effect and absence of significant decrease in the metabolism of [U-14C]glucose in the brain of pyrithiamine-treated animals in Expt. B were probably due to the fact that animals in Expt. B were older and weighed more than those in Expt. A, both at the start and the termination of the experiments.

Notes: Skin-cleansing compositions based on alkyl carboxylates (soaps) have a higher irritation potential than those based on syndet surfactants such as alkyl isethionates or alkyl ether sulphates. Contributing factors include inherent differences in the irritation potential of soaps and syndet surfactants, pH-induced changes in surfactant solution chemistry, and the direct effects of pH on the physical properties of the stratum corneum (SC). Past work has not directly addressed the effect of solution pH on the SC itself and its potential role in cleanser-induced skin irritation. In the current work, alterations to SC properties induced by buffered pH solutions and two strongly ionizable surfactants, sodium dodecyl sulphate and sodium lauryl ether sulphate, at different pH values are measured. By utilizing optical coherence tomography (OCT) and infrared (IR) spectroscopy we have directly measured physical changes in SC proteins and lipids. Our results indicate that SC swelling, which reflects alterations to SC structural proteins, is increased significantly at pH 10, compared to pH 4 and 6.5. The transition temperature (Tm) of SC lipids is found to increase at pH 10, compared to pH 4 and 6.5, suggesting a more rigid SC lipid matrix. Surfactants cause a further increase in swelling and lipid rigidity. Some aspects of what these results mean for SC physical properties as well as their implications to potential mechanisms of surfactant-induced skin irritation are discussed.

Notes: The shift of the volume plasmon energy with particle size in cadmium sulphide nanoparticles was examined by energy filtered transmission electron microscopy. This technique allowed the plasmon energy of individual, well-separated particles to be measured. The measured plasmon energy was found to increase with decreasing particle size, in general agreement with the theoretical approximation for plasmon shifting due to the quantum size effect. The nanoparticle diameters ranged between 1.5 and 3.8 nm and they were prepared by mechanochemical processing techniques and then electrophoretically deposited on the transmission electron microscope specimen grids. © 1999 American Institute of Physics.

Notes: InSb enhancement-mode, metal-insulator-semiconductor, field-effect transistors with 1 μm gate lengths have been fabricated. When operated at room temperature with less than 0.5 V applied between the source and drain, the transistors have a static dynamic range in excess of 20 dB, a cut-off frequency (fT) of 14 GHz and a transconductance, at 1 GHz, of 230 mS mm−1. Analysis of the parasitic capacitances indicates an intrinsic fT of about 90 GHz. The static electron mobility in the channel is 2×104 cm2 V−1 s−1, so a carrier velocity of about 3.7×107 cm s−1 should be attained. This leads to a predicted frequency response of 84 GHz, in reasonable agreement with the intrinsic microwave data.