Occurrence of Ti3+ and Fe2+ in Mullite

Electron paramagnetic studies showed that Ti³⁺ and Fe²⁺ occur in mullites taken from a refractory material which was fused-cast under a reducing atmosphere. Exposure of the mullite samples to temperatures >1600°C caused oxidation of Ti³⁺ and Fe²⁺ to Ti⁴⁺ and Fe³⁺, respectively.     

Effect of the lactoperoxidase system against three major causal agents of disease in mangoes

The antibacterial activity of the lactoperoxidase system (LPS) on the growth of Xanthomonas campestris, the causal agent of bacterial black spot in mangoes, Botryodiplodia theobromae, the causal agent of stem-end rot disease in mangoes, and Colletotrichum gloeosporioides, the causal agent of anthracnose disease in mangoes, was determined during culture at 30 degrees C and at several pH values (4.5, 5.5, and 6.5). When the results of using the LPS were compared with those from control cultures without the LPS reagents, the growth of the three microorganisms was totally inhibited in all of the conditions tested. Viability tests enumerating cultivable cells of X. campestris showed that the LPS had a bactericidal effect, whatever the pH value. This effect is faster at pH 5.5, corroborating the results reported in the literature (optimal pH for the LPS efficiency). Further, we proved that hydrogen peroxide alone had little inhibition effect on the growth of the microorganisms studied. This compound is essentially used to convert thiocyanate into hypothiocyanate during the lactoperoxidase reaction. The potential of the LPS for the postharvest treatment of the fruits for controlling microbial diseases was thus demonstrated. Nevertheless, further studies are needed on fresh fruits before envisaging any application.     

Radiation-grafted membrane/electrode assemblies with improved interface

Recent progress is reported in preparing membrane/electrode assemblies for polymer electrolyte fuel cells based on radiation-grafted FEP-g-poly(styrenesulfonic acid) membranes. MEAs with an improved interface between the membrane and commercially available gas diffusion electrodes were obtained by Nafion®-coating of the membrane and hot-pressing. These improved MEAs showed both, performance data comparable to those of MEAs based on Nafion® 112 and an operation lifetime in H₂/O₂ fuel cells of more than 2000 h at 60 °C and 500 mA cm⁻² current density.     

Projection of topographic maps from curved brain surfaces into a plane

The environment is represented in the brain by topographic maps. These maps and their interrelationship form a dominant feature in the brain, but unfortunately, they are often projected onto surfaces which are variously curved. It would be useful to be able to compare the topography on these surfaces quantitatively with the origin of the map. This comparison would be possible if the curved brain surfaces could be represented in planes. Therefore, it was necessary to develop a procedure for unfolding maps on convex structures like the retina and the optic tectum of the chick. For this purpose a unit sphere was constructed whose origin was close to the centre of gravity of the curved brain structure. The surface of this structure was then projected into the sphere. From its representation on the spherical surface it was unfolded into the plane using a polar azimuthal radially equidistant projection. Our method can safely be applied to convex structures only. However, it is not limited to the visual system. The mathematical procedure is formulated in such a way as to be easily implemented. It is exemplified by experiments on the optic tectum and the developing retina of the chick.     

The binding properties and biological activities of Bcl-2 and Bax in cells exposed to apoptotic stimuli

The oncogene product Bcl-2 protects cells from apoptosis whereas its homolog Bax functions to kill cells. Several binding partners of Bcl-2 and Bax have been isolated, but none of them has yet provided clues as to exactly how Bcl-2 and Bax work. According to one view, Bcl-2 and Bax interact with survival and death effector molecules, respectively, and neutralize each other through heterodimerization. Alternatively, Bcl-2 requires Bax for death protection, and additional proteins bind to the heterodimer to regulate its activity. Here we used a co-immunoprecipitation strategy to distinguish between these two possibilities. We show that the Bcl-2-Bax heterodimer is maintained, and no other protein associates stably in detectable amounts with Bcl-2, Bax, or the heterodimer in anti-Bcl-2 and anti-Bax immunoprecipitates from normal cells and cells exposed to apoptotic stimuli. Analysis of cells expressing various levels of Bcl-2 and Bax, however, revealed that the degree of protection against apoptosis does not correlate with the number of Bcl-2-Bax heterodimers but the amount of Bcl-2 that is free of Bax. In addition, the survival activity of Bcl-2 is unaffected when Bax expression is ablated by an antisense strategy. Our findings suggest that the Bcl-2-Bax heterodimer is a negative regulator of death protection, and that Bcl-2 requires neither Bax nor major, stable interactions with other cellular proteins to exert its survival function. We therefore propose that Bcl-2 acts as an enzyme (capturing substrates in a transient way), as a homodi- or multimer, or through the interaction with non-proteaceous targets (lipids, ions).     

Prenatal Exposure to Arsenic and Cadmium Impacts Infectious Disease-Related Genes within the Glucocorticoid Receptor Signal Transduction Pathway

There is increasing evidence that environmental agents mediate susceptibility to infectious disease. Studies support the impact of prenatal/early life exposure to the environmental metals inorganic arsenic (iAs) and cadmium (Cd) on increased risk for susceptibility to infection. The specific biological mechanisms that underlie such exposure-mediated effects remain understudied. This research aimed to identify key genes/signal transduction pathways that associate prenatal exposure to these toxic metals with changes in infectious disease susceptibility using a Comparative Genomic Enrichment Method (CGEM). Using CGEM an infectious disease gene (IDG) database was developed comprising 1085 genes with known roles in viral, bacterial, and parasitic disease pathways. Subsequently, datasets collected from human pregnancy cohorts exposed to iAs or Cd were examined in relationship to the IDGs, specifically focusing on data representing epigenetic modifications (5-methyl cytosine), genomic perturbations (mRNA expression), and proteomic shifts (protein expression). A set of 82 infection and exposure-related genes was identified and found to be enriched for their role in the glucocorticoid receptor signal transduction pathway. Given their common identification across numerous human cohorts and their known toxicological role in disease, the identified genes within the glucocorticoid signal transduction pathway may underlie altered infectious disease susceptibility associated with prenatal exposures to the toxic metals iAs and Cd in humans.     

Protective Layer Design in Landfill Covers based on Frost Penetration

We develop a design procedure to determine the minimum thickness of a protective soil layer over a barrier layer in a landfill cover design. The procedure equates the minimum thickness of the overlying protective layer to the predicted extreme freezing-events depth that may occur in the landfill design life. This procedure is applicable to Resource Conservation and Recovery Act Subtitle C hazardous waste landfills and any landfill designed to encapsulate hazardous waste from the environment for long periods of time. This procedure was formulated by the Uranium Mill Tailings Remedial Action Project’s Technical Assistance Contractor to protect radon and infiltration barriers from degradation over a 200-year minimum design life. The procedure uses common soil parameters, a personal computer version of the modified Berggren equation, and site-specific daily maximum-minimum temperature data compiled for a minimum of 30 years to compute frost depths. The computed frost penetration magnitudes are then used with a Gumbel extreme-value probability distribution to predict frost depths for recurrence intervals corresponding to a design life that exceeds the record of observed data.     

Staphylococcal food poisoning caused by imported canned mushrooms

From February through April 1989, four outbreaks of staphylococcal food poisoning in the United States were associated with eating mushrooms canned in the People's Republic of China (PRC). In the four outbreaks, 99 persons who ate at a suspect facility developed gastrointestinal symptoms within 24 h, including 18 who were hospitalized. Illness was associated with eating mushrooms at a university cafeteria (relative risk [RR] = 53.0), a hospital cafeteria (RR = 13.8), a pizzeria (odds ratio [OR] = infinity), and a restaurant (OR = infinity) (all P < .0001). Staphylococcal enterotoxin A was found by ELISA in mushrooms at the sites of two outbreaks and in unopened cans from the three plants thought to have produced mushrooms implicated in outbreaks. These investigations led to multistate recalls and a US Food and Drug Administration order to restrict entry into the United States of all mushrooms produced in the PRC; until this action, the United States imported approximately 50 million pounds yearly.