PubMed · 8249833
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F P Paloucek. 1993. Lead poisoning.. https://doi.org/10.1016/s0160-3450(15)30615-2
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Reactive oxygen species (ROS) are important second messengers for the induction of several genes in a variety of physiological and pathological conditions. Ultraviolet B (UVB) irradiation has recently been shown to generate lipid peroxidation products and hydroxyl radicals (HO.) with detrimental long term effects like cancer formation and premature aging of the skin. Here, we addressed the question of whether ferric/ferrous iron via the generation of ROS may mediate the UVB response, finally leading to connective tissue degradation, a hallmark in carcinogenesis and aging. Therefore, we studied the involvement of iron and ROS in the modulation of Jun N-terminal kinase 2 (JNK2) activity, c-jun and c-fos mRNA levels, key signaling steps in the transcriptional control of matrix-degrading metalloprotease (MMP)-1/interstitial collagenase and MMP-3/stromelysin-1 after UVB irradiation of human dermal fibroblasts in vitro. The iron-driven generation of lipid peroxides and hydroxyl radicals were identified as early events in the downstream signaling pathway of the UVB response leading to a 15-fold increase in JNK2 activity, a 3.5-fold increase in c-jun, to a 6-fold increase in MMP-1, and a 3.8-fold increase in MMP-3 mRNA levels, while virtually no alteration of c-fos mRNA levels were observed. Diminished generation of reactive oxygen species resulted in a significant reduction of JNK2 activity, c-jun, MMP-1, and MMP-3 mRNA levels after UVB irradiation compared with UVB-irradiated cells. Collectively, we have identified the iron-driven Fenton reaction and lipid peroxidation as possible central mechanisms underlying signal transduction of the UVB response.
A new chlorosulfonylated tetradentate beta-diketone, 4,4'-bis(1",1",1",2",2",3",3"-heptafluoro-4",6"-hexanedion-6 "-yl) chlorosulfo-o-terphenyl (BHHCT), was synthesized as a chelating label for Eu3+. BHHCT can be covalently bound to proteins under mild conditions and forms a strongly fluorescent chelate with Eu3+. Bovine serum albumin (BSA) and streptavidin (SA) were labeled with BHHCH-Eu3+, and the latter was used for time-resolved fluoroimmunoassay of alpha-fetoprotein (AFP) in human sera. A remarkably high sensitivity was obtained, with a detection limit of 4.1 x 10(-3) pg/mL, which corresponds to an improvement of about 4-5 orders of magnitude, compared to those of all conventional immunoassays including fluoroimmunoassay, enzyme immunoassay, and radioimmunoassay. The high sensitivity has been attained both by strong fluorescence of the present label and by the extremely suppressed background level brought about by the direct labeling of proteins with the beta-diketone-Eu3+ complex. A general consideration and ideas are given for designing ideal label ligands for strongly fluorescent Eu3+ complexes.
We describe a simple in vitro characterization of chelation that is useful when choosing an appropriate ligand-metal combination for clinical applications. These properties include the effect of concentration on chelation efficiency, time to maximum chelation, and stability in acidic and serum environments. The macrocyclic ligands nitro-DOTA and nitro-PADOTA, the acyclic ligands nitro-CHX-A-DTPA, nitro-MX-DTPA, DTPA, and a novel terpyridine ligand, TMT-amine, were evaluated as chelate complexes of both intermediate energy beta-emitting lanthanides lutetium-177 and samarium-153. The data were compared to results obtained in a previously published study with yttrium-90. Acid lability, time to achieve maximum chelation, and stability in human serum are properties unique to each ligand-metal combination and should be evaluated prior to choosing an appropriate combination for therapeutic applications. Concentration dependence and duration of chelation are general properties of lanthanide and yttrium chelation that can be applied to an appropriate ligand-metal combination to achieve optimum chelation efficiencies.