Potential immunological markers for diagnosis of human strongyloidiasis using heterologous antigens.

Strongyloides venezuelensis is a parasitic nematode of rodents that is frequently used to obtain heterologous antigens for immunological diagnosis of human strongyloidiasis. The aim of this study was to identify antigens from filariform larvae of S. venezuelensis for immunodiagnosis of human strongyloidiasis. Soluble and membrane fractions from filariform larvae of S. venezuelensis were obtained in phosphate saline (SS and SM) and in Tris-HCl buffer (TS and TM), and were analysed by Western blotting. Different antigenic components were recognized by IgG antibodies from the sera of strongyloidiasis patients. Highest recognition was observed for a 30-40 kDa mass range present in all antigenic fractions. The band encompassing this mass range was then excised and subjected to mass spectrometry for protein identification. Immunoreactive proteins identified in the soluble fractions corresponded to metabolic enzymes, whereas cytoskeletal proteins and galectins were more abundant in the membrane fractions. These results represent the first approach towards identification of S. venezuelensis antigens for use in immunodiagnostic assays for human strongyloidiasis.

Diagnosis of the strongyloid nematode Strongyloides venezuelensis in experimentally infected rats.

Strongyloides venezuelensis is an intestinal nematode of rats, frequently used as a model for studying human and animal strongyloidiasis. In the present study, we evaluated parasitological, serological and molecular methods for the diagnosis of experimental S. venezuelensis in rats, Rattus norvegicus. Blood and faecal samples were collected and analysed up to 60 days post infection (pi) with adult worm recovery occurring from 5 to 45 days pi. Using an enzyme-linked immunosorbent assay (ELISA), serum levels of IgG antibodies increased up to 28 days pi, thereafter decreasing by day 60 pi. Polymerase chain reaction (PCR) assays detected S. venezuelensis DNA in faecal samples of rats from 5 to 21 days pi. The present study therefore represents the first step towards improving the diagnosis of experimental strongyloidiasis.

The effect of the nano-silica support on the catalytic reduction of water by gold, silver and platinum nanoparticles--nanocomposite reactivity.

Pt°-NPs, prepared by the reduction of Pt(IV) salts with borohydride, do not catalyse the reduction of water in the presence of the strongly-reducing ˙C(CH3)2OH radicals. However, supporting the same metal nanoparticles (M°-NPs) with SiO2 alters the catalytic properties enabling the reaction. This effect depends both on the nature of M° and concentration of the composite nanoparticles. At low nanocomposite concentration: for M = Au nearly no effect is observed; for M = Ag the support decreases the catalytic reduction of water and for M = Pt the support initiates the catalytic process. At high nanocomposite concentration: for M = Au the reactivity is considerably lower and for M = Ag or Pt no catalysis is observed. Furthermore, for M = Ag or Pt H2 reduces the ˙C(CH3)2OH radicals.

Modeling the effect of facial topographies upon the visual field of humans and primates.

PURPOSE: To establish a virtual device that can predict the effect of facial features on the visual field of humans and primates. METHODS: Virtual masks were obtained from human subjects, and macaque, chimpanzee and baboon taxidermic specimens, and aligned with upright head orientation at the center of a virtual perimeter-like dome (radius = 50 m) developed with Cinema 4D. Virtual searchlights positioned at the masks' pupils were then allowed to 'paint' facial elements obstructing their path, and demarcate the unobstructed rays at the perimetric surface and on a virtual ground floor related to eye level. Searchlight positions along the human mask's pupillary axis were identified by maximum congruence to Goldmann visual field limits. RESULTS: The human contours largely concur with large-stimulus isopters displaying the limiting role of the nasal ridge, and the relatively extended ventral and temporal limits. In contrast, the facial design of chimpanzees and baboons obstructs significant portions of the ventral foreground (>2 m cf < 0.5 m in human), while there appear to be larger binocular overlaps (125 degrees in chimp cf 90 degrees in human). CONCLUSIONS: The model provides information on anatomical constraints for monocular and binocular visual field extensions including projection of the ventral field on a virtual floor.

Reactions of radicals with hydrolyzed Bi(III) ions: a pulse radiolysis study.

Radiolytic reduction of BiOClO4 in aqueous solutions leads to the formation of bismuth clusters and larger nanoparticles. The mechanisms of redox reactions of the polycationic Bi(III) species that exist in the solution were investigated with pulse radiolysis. The kinetic and spectral properties of the transients formed by the reaction of these species with the primary radicals from water radiolysis are reported. The single-electron reduction product, Bi9(OH)224+, absorbs at lambdamax = 273 nm, while the OH adduct, Bi9(OH)235+, has a broad absorption spectrum with a maximum at 280 nm and a shoulder at 420 nm. Several rate constants were measured: k (e-aq + Bi9(OH)225+) = 1.2 x 1010 M-1 s-1 and k (OH + Bi9(OH)225+) = 1.5 x 109 M-1 s-1. The reduced species, Bi9(OH)224+ further reacts with (CH3)2COH radicals, but not with CH2C(CH3)2OH radicals from t-butanol, to produce a doubly reduced polynuclear species. A few reactions of the reduction of the Bi salt in the presence of poly(acrylic acid) are also described. In the presence of the polymer, a metal-polymer complex is formed prior to the irradiation, and the reduction reactions are significantly slowed down.

Radiolytic hydrogen yields in aqueous suspensions of gold particles.

The effect of high concentrations of large gold particles, in the hundreds of nanometer size regime, on the yields of molecular hydrogen, G(H(2)), produced in the radiolysis of several aqueous solutions was determined. In particular we look for direct effect of radiation absorbed by the solid particles on the yield of water products. These particles, however, are catalytically active in the conversion of reducing radicals to molecular hydrogen as well. A very small increase in G(H(2)) observed in bromide solutions upon addition of 50 wt % of gold particles indicates that the radiolysis of the solid particles does not affect the yields in the aqueous phase. Very little exchange of charge carriers or energy between the two phases occurs in these large particle suspensions. On the other hand, efficient catalytic conversion of (CH(3))(2)C(*)OH radicals to H(2) is shown to occur. The efficiency of the presently studied suspensions in the redox-catalytic process is similar to that of suspensions of small particles of similar total surface area. In the presence of radicals from hydrogen atom abstraction from tert-butyl alcohol the yield decreases significantly, again similar to the behavior in suspensions of small particles. We conclude that the redox catalysis does not depend on the size of the particles when their size exceeds a few nanometers.

XAFS studies of gold and silver-gold nanoparticles in aqueous solutions.

The x-ray absorption fine structure (XAFS) of colloidal Au and Au/Ag nanoparticles (3.5nm and 20nm mean diameter) in an aqueous solution has been investigated. Size dependent alloying was observed upon deposition of Ag on Au core. Ag forms distinct layers around the 20 nm Au nanoparticles. In contrast, random mixing is found for Ag deposited on 3.5nm Au particles.

A light and electron microscope study of aging parotid and submandibular salivary glands of Swiss-Webster mice.

Light and electron microscope comparisons were made of parotid and submandibular glands from male Swiss-Webster white mice 3, 13, and 18 months old. The glands from the 13- and 18-month-old mice were less organized and the parenchyma was not as dense. Fibrous connective tissue, intracellular lipofuscin granules, and residual body formation increased with age. In the cells of the parotid glands of 18-month-old mice, the nucleus-to-cytoplasm ratio was greater than in the specimens from the younger two ages. The granular convoluted tubules in submandibular glands of 18-month-old mice were the smallest of all age groups. The age changes appear comparable to those of rat and human salivary glands, yet this is an inexpensive animal model that achieves old age in less time than other animal models.

Lingual changes in ageing mice by light- and scanning electron-microscopy.

Tongues from young, old and senescent Swiss-Webster white mice were compared. Sections and tissues were taken from the anterior, posterior, and ventral regions. The epithelium became atrophic and hyperkeratotic in the senescent animals. The filiform papillae were blunted, atrophic and disorganized across the entire dorsal surface in the older animals. The ventral aspect in the senescent animals had thinning epithelium, a hyperchromatic germinal layer, and a roughened, disorganized surface.

Effects of parathyroidectomy and hemigastrectomy on exocrine pancreatic secretion on dogs.

The effects of parathyroidectomy on secretory functions of the pancreas were studied in a group of dogs with previous hemigastrectomy. Free flow of pancreatic juice was obtained by direct cannulation of the main pancreatic duct. A gastric fistula prevented the entry of gastric acid into the duodenum. Parathyroidectomy caused a significant decrease in the secretin-induced volume and bicarbonate secretion. Pentagastrin administration produced a slight increase in volume and bicarbonate secretion which remained below preparathyroidectomy levels. These results were not dependent on calcium blood levels and did not change after calcium administration to the hypocalcemic-parathyroidectomy dog. It is suggested that parathyroid hormone effect on pancreatic secretion is not mediated via gastrin but due at least in part to direct action on the parenchyma.

The one-electron transfer redox potentials of free radicals. I. The oxygen/superoxide system.

The method of determination of Redox potentials of radicals, using the pulse radiolysis technique, is outlined. The method is based on the determination of equilibrium constants of electron transfer reactions between the radicals and appropriate acceptors. The limitations of this technique are discussed. The redox potentials of several quinones-semiquinones are calculated, as well as the standard redox potential of the peroxy radical. EO2/O2=-0.33 V and the redox oxidation properties of the peroxy radical in various systems and pH are discussed. The value determined for the redox potentials of O2/O2 is higher by more than 0.2 V than earlier estimates, which has important implications on the possible role of O2 in biological processes of O2 fixation.

Frequency Dependence of Polarization of Pulsar CP 0328.

The circularly polarized emission from the pulsar CP 0328 has an approximately flat spectrum in the 1-megahertz band centered at 113.6 megahertz, whereas the linearly polarized emission varies with frequency and from pulse to pulse. A simple model for the source that has a constant Faraday rotation measure fits some of the linearly polarized spectra observed for individual pulses, but changes in the rotation measure of as much as 30 radians per square meter are required between adjacent pulses. The simple model does not fit the average spectrum of the linearly polarized emission, although the average spectrum had the same form on two nights.