Search results for "guanidine"
showing 10 items of 78 documents
Synthesis, characterization and thermal degradation of 8-hydroxyquinoline–guanidine–formaldehyde terpolymer
2007
Abstract Terpolymer (8-HQGF) has been synthesized using the monomers 8-hydroxyquinoline, guanidine, formaldehyde in 1:1:2 molar proportions. The structure of 8-HQGF terpolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, i.e. UV–Visible, FTIR–ATR and 1 H NMR spectroscopy. Detailed thermal degradation study of the new terpolymer has been carried out to ascertain its thermal stability. Thermal degradation curve is discussed which shows two decomposition steps (265–475 °C and 540–715 °C). Sharp–Wentworth and Freeman–Carroll methods have been used to calculate activation energies and thermal stability. The activation energy ( E a ) calculated by…
Apaf-1 deficient mouse fibroblasts are resistant to MNNG and MMS-induced apoptotic death without attenuation of Bcl-2 decline.
2005
Abstract Simple alkylating agents induce cell death by activating the apoptotic pathway. In rodent fibroblasts, apoptosis triggered by DNA methylation lesions is executed via the mitochondrial damage pathway. Here, we studied cell death induced by the methylating agents methyl methanesulfonate (MMS) and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) in mouse fibroblasts wild-type (wt) and deficient for Apaf-1 (apaf-1 knockout cells). Apaf-1 is an essential component of the apoptosome complex that becomes activated upon cytochrome c release from mitochondria. We show that apaf-1 knockout cells are more resistant to the cytotoxic effect (as measured by WST assay) of methylating agents. This is d…
Experimental inhibition of nitric oxide increases Plasmodium relictum (lineage SGS1) parasitaemia.
2012
7 pages; International audience; Malaria is a widespread vector-borne disease infecting a wide range of terrestrial vertebrates including reptiles, birds and mammals. In addition to being one of the most deadly infectious diseases for humans, malaria is a threat to wildlife. The host immune system represents the main defence against malaria parasites. Identifying the immune effectors involved in malaria resistance has therefore become a major focus of research. However, this has mostly involved humans and animal models (rodents) and how the immune system regulates malaria progression in non-model organisms has been largely ignored. The aim of the present study was to investigate the role of…
Mouse embryonic stem cells are hypersensitive to apoptosis triggered by the DNA damage O(6)-methylguanine due to high E2F1 regulated mismatch repair.
2007
Exposure of stem cells to genotoxins may lead to embryonic lethality or teratogenic effects. This can be prevented by efficient DNA repair or by eliminating genetically damaged cells. Using undifferentiated mouse embryonic stem (ES) cells as a pluripotent model system, we compared ES cells with differentiated cells, with regard to apoptosis induction by alkylating agents forming the highly mutagenic and killing DNA adduct O(6)-methylguanine. Upon treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), ES cells undergo apoptosis at much higher frequency than differentiated cells, although they express a high level of the repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). Apo…
Soil mutagens are airborne mutagens: variation of mutagenic activities induced in Salmonella typhimurium TA 98 and TA 100 by organic extracts of agri…
2000
As our hypothesis was that soil mutagens are airborne mutagens, possibly modified by soil microorganisms, we checked solvent extracts from agricultural and forest soils collected during late summer in the environment of Mainz, a region highly charged by anthropogenic air pollution, or near Bayreuth, a rural low charged region of Germany, or in a remote region of western Corsica without anthropogenic air pollution for the presence of mutagenicity in Salmonella typhimurium. Levels of mutagenic activities were quantified by calculation of revertants/g from the initial slope of dose-response curves applying tester strains S. typhimurium TA 98 and TA 100 in the absence and presence of an activat…
Involvement of NO in contact hypersensitivity.
1998
The NO synthases (NOS) generate NO from L-arginine. High concentrations of NO have been shown to be responsible for tissue injury and cell death, while low concentrations of NO induce vasodilatation and other signaling effects. We have investigated the involvement of NO in contact hypersensitivity (CHS) reactions. CHS induced by treatment of BALB/c mice with the contact allergen 2,4-dinitrofluorobenzene (DNFB) was significantly reduced by the NOS inhibitor N-methyl-L-arginine (L-NMA), but not by the stereoisomer D-NMA, as shown by reduced ear swelling responses and evaluation of ear tissue sections. The CHS response was also reduced by aminoguanidine, which is known to preferentially inhibi…
Metal coordination of azurin in the unfolded state.
1998
Abstract1H NMR data applied to the paramagnetic cobalt(II) derivative of azurin from Pseudomonas aeruginosa have made it possible to show that the metal ion is bound to the protein in the unfolded state. The relaxation data as well as the low magnetic anisotropy of the metal ion indicate that the cobalt ion is tetrahedral in the unfolded form. The cobalt ligands have been identified as the residues Gly45, His46, Cys112 and His117. Met121 is not coordinated in the unfolded state. In this state, the metal ion is not constrained to adopt a bipyramidal geometry, as imposed by the protein when it is folded. This is clear confirmation of the rack-induced bonding mechanism previously proposed for …
Evaluation of the SOS/umu-test post-treatment assay for the detection of genotoxic activities of pure compounds and complex environmental mixtures.
2000
This study presents an evaluation of the SOS/umu-test after introducing an additional dilution and incubation in the post-treatment assay. This treatment reduces the influence of coloured test compounds that otherwise affect the colorimetric determination of the beta-galactosidase activity and the bacterial growth measurement during the testing of complex environmental samples. The post-treatment assay significantly increased the beta-galactosidase activity and consequently the enzyme induction ratios at higher doses of model genotoxins 4-nitroquinoline-N-oxide, N-methyl-N'-nitro-N-nitrosoguanidine, 2-aminoanthracene, benzo(a)pyrene with low or no effect on the sensitivity of the test itsel…
Poly(ethylene glycol) diacrylate-based solid-phase extraction for determination of sulfonamides in meat samples
2020
Abstract In this work, a sorbent based on poly(ethylene glycol) diacrylate (PEGDA) polymer has been synthesized for solid-phase extraction (SPE) of sulfonamides (sulfaguanidine, sulfadiazine, sulfathiazole, sulfapyridine, sulfamethazine, sulfamonomethoxine, sulfamethoxazole, sulfisoxazole) from different meat matrices, which were subsequently determined by HPLC-DAD. Several extraction parameters such as loading and elution solvents as well as other variables (loading capacity, breakthrough volume and reusability) influencing on the analytical performance of the sorbent were optimized. Under the optimal conditions, the developed method was successfully applied to determine the eight sulfonam…
CCDC 880661: Experimental Crystal Structure Determination
2012
Related Article: A.L.Brazeau, M.M.Hanninen, H.M.Tuononen, N.D.Jones, P.J.Ragogna|2012|J.Am.Chem.Soc.|134|5398|doi:10.1021/ja300587z