Cyclic AMP is not detectable in Clostridium perfringens

Cyclic AMP was not detected (less than 5 X 10(-9) M intracellular concentration) at any stage of growth or sporulation of two strains of Clostridium perfringens grown with or without methylxanthines. Only Bacillus and Lactobacillus, genera belonging to the same phylogenetic cluster, have previously exhibited undetectable levels of cyclic AMP.     

Study in the anuran amphibian Xenopus laevis, some blood characteristics and nitrogen excretion based on changes in the water osmolarity]

The pH, the osmolality and the urea and ammonia concentrations in blood, as well as the net urea and ammonia excretions, were studied in the amphibian Xenopus laevis exposed for several weeks to increased osmotic pressure (OP) of the ambient water, as a result of the addition of either NaCl or mannitol to the water. The pH and the ammonia concentration of the blood were independent of the variations of the ambient osmolarity. On the contrary, the blood osmolality and its urea concentration increased markedly when the ambient OP was augmented. The increase of ambient OP by NaCl addition to the medium augmented the urea net excretion and slightly decreased the ammonia excretion. When the increase of ambient OP resulted from the addition of mannitol in the water, excretions of urea and ammonia became negligible.     

A numerical taxonomic study of Flavobacterium-Cytophaga strains from dairy sources

Phenotypic data on 203 Gram-negative non-fermentative bacteria of the Flavobacterium-Cytophaga group isolated from milk and butter were analyzed by numerical taxonomic techniques. Twenty reference strains including species of Flavobacterium, Cytophaga and strains of Pseudomonas paucimobilis were included in the study. Using the matching coefficient of Sokal & Michener with antibiotic susceptibility data included, 139 isolates were recovered in nine clusters. Six of these clusters were linked at or above the 85% S level while three were linked at or above the 79% S level. The largest cluster, representing 46.3% of the isolates, could be equated with Flavobacterium sp. Group IIb. Other clusters could be equated with Flavobacterium sp. L 16/1 (22.7% of isolates), F. balustinum (10.8% of isolates), F. breve (4.4%), F. multivorum (3.5%) and Cytophaga johnsonae (1.5%). The cluster resembling Flavobacterium sp. L 16/1 and a smaller unclassified cluster, were exceptional in being susceptible to the antibiotics cephalothin and penicillin G.     

Study of human erythrocyte membrane proteins by 2-dimensional electrophoresis

Fractionation of human erythrocyte membrane proteins was performed using a modification of two-dimensional gel electrophoresis described by P. O'Farrel with isoelectric point plotted against molecular mass. All major erythrocyte proteins, including high molecular weight proteins, such as spectrin and band 3 protein, identified by one-dimensional sodium dodecyl sulfate gel electrophoresis, were visualized by silver staining of two-dimensional gels. All in all about 50 polypeptides were distinguished on two-dimensional electrophoretic patterns. Preliminary protein map was developed.     

Effects of 1-ethynylpyrene and related inhibitors of P450 isozymes upon benzo[a]pyrene metabolism by liver microsomes

The effects of three aryl acetylenes, 1-ethynylpyrene (EP), 2-ethynylnaphthalene (EN) and 3-ethynylperylene (EPE), upon the metabolism of benzo[a]pyrene (BaP) by microsomes isolated from rat liver were investigated. These aryl acetylenes all inhibited the total metabolism of BaP. Formation of BaP 7,8-dihydrodiol and BaP tetrol products by microsomal preparations from rats that had been pretreated with 3-methylcholanthrene (3MC) were preferentially inhibited. The effects of EP upon the metabolism of BaP 7,8-dihydrodiol by microsomes from rat liver were also studied. This aryl acetylene strongly inhibited the formation of BaP tetrols from BaP 7,8-dihydrodiol by liver microsomes both from untreated rats and from rats pretreated with 3MC, but enhanced the conversion of the BaP dihydrodiol into other metabolites.     

Cyclo(His-Pro) up-regulates heme oxygenase 1 via activation of Nrf2-ARE signalling

Paraquat (1,1'-dimethyl-4,4'-bipyridinium), a widely used non-selective herbicide, is a redox cycling agent with adverse effects on dopamine systems. Epidemiological data have shown that exposure to paraquat is one of the several risk factors for Parkinson's disease. We have already shown that cyclo(His-Pro), an endogenous cyclic dipeptide produced by the cleavage of the thyrotropin releasing hormone, has a cytoprotective effect through a mechanism involving Nrf2 activation that decreases production of reactive oxygen species and increases glutathione synthesis. Using primary neuronal cultures and PC12 cells as targets of paraquat neurotoxicity, we addressed whether and how cyclo(His-Pro) causes cellular protective response against paraquat-mediated cell death. We found that cyclo(His-Pro) attenuated reactive oxygen species production, and prevented glutathione depletion by up-regulating Nrf2 gene expression, triggering its nuclear accumulation and activating the expression of heme oxygenase1. These protective effects were abolished by RNA interference-mediated Nrf2 knock down whereas were unaffected by RNA interference-mediated Keap1 knock down. Inhibition of heme oxygenase activity decreased cyclo(His-Pro)-induced neuroprotection. These results suggest that cyclo(His-Pro), acting as a selective activator of the brain modulable Nrf2 pathway, may be a promising candidate as neuroprotective agent that act through induction of phase II genes.