Biphasic role of platelet-activating factor in oral mucosal ulcer healing

Platelet-activating factor (PAF) is a potent phospholipid-derived messenger molecule involved in a number of pathological conditions, including mediation of inflammatory cascades associated with wound healing. We investigated prophylactic and therapeutic effects of a specific PAF antagonist, BN52020, on the course of experimentally induced oral mucosal ulcer healing. The prophylactic BN52020 administration produced an accelerated ulcer healing that was characterized by a marked induction in COX-2 enzyme protein expression and the substantial decline in apoptosis, TNF-alpha, and NOS-2 activity. A delay in ulcer healing, however, occurred with the therapeutic BN52020 administration, and this effect of the agent was reflected in a decreased expression of COX-2 protein, higher rate of apoptosis, and the elevated level of TNF-alpha and NOS-2. Our findings implicate PAF requirement in orderly progression of the events involved in oral tissue repair, and suggest that the interference with its actions during healing process results in the suppression of COX-2-derived anti-inflammatory prostaglandins that delay the mucosal repair.     

Biochemical and proteomic effects in Procambarus clarkii after chlorpyrifos or carbaryl exposure under sublethal conditions

In vivo effects of two sublethal doses of chlorpyrifos and carbaryl were studied in Procambarus clarkii after 2 and 7 days of exposure, and after pesticide removal. Chlorpyrifos inhibited carboxylesterase activity in a concentration-dependent manner, but acetylcholinesterase was less sensitive. Compared with chlorpyrifos, carbaryl had a less marked effect on esterase activity. The effects of selected pesticides on biotransformation or oxidative stress biomarkers were contradictory. Chlorpyrifos lowered ethoxyresorufin-O-deethylase (EROD), catalase and oxidized glutathione (GSSG) levels but raised glutathione-S-transferase activity, while carbaryl raised EROD, catalase and glutathione-S-transferase, but lowered glutathione peroxidase and reduced glutathione (GSH) levels. The effects on protein expression patterns depending on pesticide type and the tissue used for analysis were studied in parallel by 2-DE. In gill and nervous tissue about 2000 spots (pI 4–7) were resolved, with quite different expression patterns. Chlorpyrifos altered 72 proteins, mostly in nervous tissue, and carbaryl 35, distributed evenly between organs. Several specific spots were selected as specific protein expression signatures for chlorpyrifos or carbaryl exposure in gills and nervous tissue, respectively.     

Synaptic clusters of MHC class II molecules induced on DCs by adhesion molecule-mediated initial T-cell scanning

Initial adhesive contacts between T lymphocytes and dendritic cells (DCs) facilitate recognition of peptide-MHC complexes by the TCR. In this report, we studied the dynamic behavior of adhesion and Ag receptors on DCs during initial contacts with T-cells. Adhesion molecules LFA-1- and ICAM-1,3-GFP as well as MHC class II-GFP molecules were very rapidly concentrated at the DC contact area. Binding of ICAM-3, and ICAM-1 to a lesser extent, to LFA-1 expressed by mature but not immature DC, induced MHC-II clustering into the immune synapse. Also, ICAM-3 binding to DC induced the activation of the Vav1-Rac1 axis, a regulatory pathway involved in actin cytoskeleton reorganization, which was essential for MHC-II clustering on DCs. Our results support a model in which ICAM-mediated MHC-II clustering on DC constitutes a priming mechanism to enhance antigen presentation to T-cells.     

Metabolic alterations in K562 cells exposed to taxol and tyrphostin AG957: 1H NMR and biochemical studies

K562 cells exposed for 3 h to taxol or taxol plus tyrphostin AG957 exhibited a significant variation in the concentration of the water-soluble metabolites glutathione, myo-inositol and phosphorylcholine, as evaluated by (1)H NMR up to 72 h incubation in drug-free medium. Cells treated with both drugs showed an increase of glutathione and glutathione reductase at 24 h and a sharp decrease of myo-inositol between 8 and 24 h. Phosphorylcholine increased at 8 h both in taxol and taxol plus AG957-treated cells, which was then abruptly inverted to a significantly lower concentration at 24 h, subsequently increasing again to values higher than those found in taxol-treated and control cells. All the above reported effects were lacking in cells exposed to AG957 alone. These modifications, despite the enhancement of the overall apoptotic cascade in taxol plus AG957-treated cells, can be related to the activation of cellular detoxification mechanisms, to the correct osmolarity maintenance, and to alterations of phospholipid metabolism.     

Cryptococcus neoformans arthritis in a renal transplant recipient

We present a Cryptococcus neoformans knee joint infection in a diabetic renal transplant patient treated with steroids, cyclosporin, and mycofenolate mofetil. We discuss reported cases of cryptococcal arthritis.     

Zymomonas mobilis ATCC 10988 plasmid pZMO3 expresses mobilisation functions in Escherichia coli JM83 and RR1

Zymomonas mobilis plasmid pZMO3, equivalent to pZM2 the complete nucleotide sequence of which has been published (Misawa and Nakamura, 1989), expressed mobilisation functions in Escherichia coli JM83 and RR1 when fused to the HindIII site of pUC19. Experimental evidence based on filter mating and DNA sequence analysis supports that an ORF of pZMO3 coding for a 66 kd protein should be responsible for self-mobilisation ability.