Is prostaglandin E the neural mediator of the febrile response? The case against a proven obligatory role.

We have reviewed the evidence in favor of a prostaglandin mediator of the thermal responses in fever and found that PGE injected into the hypothalamus does not always cause fever, that cerebrospinal fluid concentrations of PGE are not reliable reflections of hypothalamic events, and that antipyretic drugs may act in ways other than inhibiting PGE synthesis. Fever is not blocked by prostaglandin antagonists, nor by ablation of PGE-sensitive areas of the brain. There is poor correlation between the effects of pyrogens and of PGE on cerebral neurons. There is evidence that at least one prostanoid other than prostaglandin is a mediator of fever, but the prostanoid has not been identified yet. We conclude that PGE may contribute to the neural responses in fever but is not essential.     

Mapping and analysis of protein sulfhydryl groups by modification with 2-bromoacetamido-4-nitrophenol

A method for identifying cysteine-containing peptides in proteins is presented using 2-bromoacetamido-4-nitrophenol (BNP) to introduce an easily detectable probe. The formation of a covalent bond between the protein sulfhydryl group and the acetamido moiety of BNP introduces a chromophore with an absorbance maximum at 410 nm. The modified protein can then be cleaved with appropriate proteases and the resulting peptides separated by chromatographic methods. Monitoring the effluent at a single wavelength (405 nm) provides a rapid and simple method of detecting and isolating only those peptides which contain cysteine residue(s). The nitrophenol derivative is stable under conditions required for protease cleavage. The reagent is therefore useful for locating cysteine-containing peptides in protein digests and can be used to explore the accessibility of different cysteines under a variety of conditions. The ease of modification, specificity of reaction, product stability, and simple detection of modified peptides make BNP ideal for investigation of cysteine residues.     

Comparison of Karanjin with other nitrification inhibitors for retardation of nitrification of urea N in soil

Summary Comparative evaluation of Kranjin and three patented nitrification inhibitors for retardation of nitrification of urea in a sandy clay loam showed that the effectiveness of the compounds tested decreased in the order: Nitrapyrin>Karanjin>A.M.>dicyandiamide.     

Cellular response to oxidative stress at sulfhydryl group receptor sites on the erythrocyte membrane

Ellman's reagent was used to induce an oxidative stimulus on the exofacial membrane sulfhydryl groups of the human erythrocyte. Thiol-disulfide exchange occurring extracellularly was monitored using resonance Raman spectroscopy, and intracellular changes were observed by 1H spin echo nuclear magnetic resonance spectroscopy of the intact cell. The stimulus caused oxidation and depletion of the glutathione pool, which was followed at higher concentrations of Ellman's reagent by a depletion of intracellular ergothioneine levels. Larger changes are induced intracellularly than would be expected from the stoichiometry of the reaction at the exofacial surface. A mechanism is proposed which links exofacial sulfhydryl receptor sites via the transport proteins to spectrin and glutathione. The consequences for the cellular redox balance of an extracellular stimulus of this type are discussed.     

Preparation of chloroplast DNA from pea plastids isolated in a medium of high ionic strength

A simple, rapid, and inexpensive method for the preparation and purification of chloroplast DNA (cpDNA) from pea has been developed. The crucial step is the isolation of chloroplasts in a medium of high ionic strength (I congruent equal to 1.40 M). CpDNA from pea prepared according to this method has successfully been used for restriction enzyme mapping, Southern transfers, and cloning.     

Arsenic Bioaccumulation in Freshwater Fishes

The arsenic ambient water quality criterion (AWQC) for protection of human health via ingestion of aquatic organisms is currently 0.14 μ g/L. This AWQC is derived using a bioconcentration factor (BCF) of 44, which is a consumption-weighted average based on two data points for oysters and fish that was proposed by the U.S. Environmental Protection Agency in 1980 for broad application to freshwater and marine environments. This BCF is based on the assumption that bioaccumulation is a simple linear function of the exposure concentration. In the nearly quarter of a century since this BCF was promulgated, there have been additions to the arsenic bioaccumulation database and a broader scientific understanding of bioaccumulation mechanisms and how they can be applied to estimating tissue concentrations in aquatic organisms. From this database, we identified 12 studies of arsenic bioaccumulation in freshwater fishes in order to explore differences in laboratory-generated BCFs and field-generated bioaccumulation factors (BAFs) and to assess their relationship to arsenic concentrations in water. Our analysis indicates that arsenic concentrations in tissue and arsenic BAFs may be power functions of arsenic concentration in water. A power function indicates that the highest BCF values may occur at low background levels and may decrease as environmental concentrations increase above the ambient range.