PubMed · 8560639
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S LaBranche. 1995. [New antidepressive agents].. https://pubmed.ncbi.nlm.nih.gov/8560639/
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We described a new approach to sensing of carbon dioxide based on photoinduced electron transfer (PET) quenching. Fluorophores like naphthalene and anthracene are known to be quenched by unprotonated amines by the PET mechanism. We examined the fluorescence spectral properties of two amine-containing fluorophores, 1-naphthylmetylamine (NMA) and 9-ethanolaminomethylanthracene (EAA). When dissolved in an organic solvent, both fluorophores displayed increased intensity when equilibrated with gaseous carbon dioxide. In the case of NMA, we found that the mean lifetime increased with increasing partial pressures of CO(2). The intensity and lifetime changes of NMA are completely reversible when CO(2) is removed by purging with argon. Our results are consistent with decreased quenching by the covalently linked amino groups when CO(2) is dissolved in the solution. At present, we are not certain whether the increased intensity is due to protonation of the amino groups or to carbamate formation. In either event, these results suggest that CO(2) can be detected directly using amine-containing fluorophores without the use of bicarbonate and a pH-sensitive fluorophore.
PURPOSE: Poly(ADP-ribose) polymerase (PARP; EC 2.4.2.30) is a chromatin-bound enzyme which is known to regulate chromatin structure by poly(ADP-ribosyl)ation of nuclear proteins, to facilitate DNA base excision repair, and to contribute to cellular recovery following DNA damage. Because inhibitors of PARP are able to potentiate the cell-killing effects of some DNA-damaging agents and to inhibit the repair of induced DNA strand breaks, such compounds may enhance the anti-tumour efficacy of radiotherapy or cytotoxic drug treatment. The PARP-inhibitory effects and radiosensitization of a new compound, 4-amino-1,8-naphthalimide (ANI), were examined. MATERIALS AND METHODS: The inhibition of radiation-induced poly(ADP-ribosyl)ation (50 Gy; 60Co gamma-radiation) was evaluated by immunofluorescence assay using MoAb 10H directed against poly(ADP-ribose). Cell survival was assessed by colony forming assay (CFA) to determine the cytotoxicity of radiosensitization potential in exponentially growing hamster lung fibroblasts (V79), rat prostate carcinoma (R3327-AT1) and human prostate carcinoma (DU145) cells. RESULTS: At concentrations above 30 nmol x dm(-3) ANI, radiation-induced poly(ADP-ribose) was not detectable by immunofluorescence in V79, AT1 and DU145 cells. At the highest concentration tested for chronic exposure (20 micromol x dm(-3)), ANI was not cytotoxic and significantly potentiates the cytotoxicity of gamma-irradiation. The level of radiation enhancement was directly proportional to drug concentration. Survival curves for the three cell lines using 20 micromol x dm(-3) ANI revealed sensitizer enhancement ratios of 1.3 for V79, 1.5 for AT1 and 1.3 for DU145. CONCLUSIONS: In living cells, ANI is about 1000-fold more potent at inhibiting PARP activity compared with 3-aminobenzamide (3-ABA). CFA studies demonstrated that ANI is a radiation sensitizer at non-toxic and lower concentrations (20 micromol x dm(-3)) than 3-ABA (10 mmol x dm(-3)).
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