At higher temperatures the genotoxicity DNA adducts and mutagenicity rapidly declined to very low levels

Different petroleum products showed a more than 100-fold range in DNA adduct formation, with severely hydrotreated base oil and bitumen fume condensates being lowest. Coal tar distillates showed ten times higher levels of DNA adduct formation than the most potent petroleum distillate. A clustered DNA adduct pattern was seen over a wide distillation range after metabolic activation with liver extracts of rat or human origin. These clusters were eluted in a region where alkylated aromatic hydrocarbons could be expected. The DNA adduct patterns were similar for base oil and bitumen fume condensates, whereas coal tar distillates had a wider retention time range of the DNA adducts formed. Reference substances were tested in the same in vitro assay.

Photoresponsive Acid Precursor - and three-ringed nonalkylated aromatics were rather low in genotoxicity, but some of the three- to four-ringed alkylated aromatics were very potent inducers of DNA adducts. Compounds with an amino functional group showed a 270-fold higher level of DNA adduct formation than the same structures with a nitro functional group. The most potent DNA adduct inducers of the 16 substances tested were, in increasing order, 9,10-dimethylanthracene, 7,12-dimethylbenz[a]anthracene and 9-vinylanthracene. Metabolic activation with human and rat liver extracts gave rise to the same DNA adduct clusters. When bioactivation with material from different human individuals was used, there was a significant correlation between the CYP 1A1 activity and the capacity to form DNA adducts. This pattern was also confirmed using the CYP 1A1 inhibitor ellipticine. The 32P-HPLC method was shown to be sensitive and reproducible, and it had the capacity to separate DNA adduct-forming substances when applied to a great variety of petroleum Prader-Willi and Angelman syndromes: diagnosis with a bisulfite-treated The putative promoter region of the SNRPN gene contains a CpG island which is heavily methylated in the maternally derived allele and unmethylated in the paternally derived allele.

In patients with Prader-Willi syndrome (PWS) only the methylated allele is present, while in those with Angelman syndrome (AS) only the unmethylated allele is present. Seebio Photochemical Acid-forming Compound of this paper is to report a polymerase chain reaction (PCR)-based assay to evaluate methylation status of the CpG island of the SNRPN gene and to show that this assay allows rapid diagnosis of PWS and AS. Methylated cytosines in the CpG dinucleotide are resistant to chemical modification by sodium bisulfite. In contrast, bisulfite treatment converts all unmethylated cytosines to uracil. Based on this differential effect, the bisulfite-modified DNA sequence of a methylated allele was successfully distinguished from that of an unmethylated allele using 2 sets of allele-specific primer pairs: a methylated allele-specific primer pair (MET) and an unmethylated allele-specific primer pair (UNMET). Bisulfite-modified DNA from 10 patients with PWS amplified only with the MET pair while modified DNA from 5 patients with AS amplified only with the UNMET pair. Modified DNA from 50 normal unrelated individuals amplified with both primer pairs.

In that methylation-specific PCR (MSPCR) can detect all presently testable causes of PWS and AS in a rapid and cost-effective fashion, serious consideration should be given to the use of this test in the initial evaluation of all patients in which Photo-induced affinity labeling of Escherichia coli ribosomes by Le Goffic F, Capmau ML, Chausson L, Bonnet D.In order to obtain more information about the binding site for chloramphenicol (D-threo diastereoisomer) on the bacterial ribosome, photo-affinity labeling experiments of this receptor have been performed with [3H]chloramphenicol itself. Control experiments show that this drug can be split photochemically by ultraviolet irradiation, whereas the ribosome is not modified structurally or functionally by such a treatment. When photolysis of a mixture of chloramphenicol and ribosomes is performed under critical conditions, some proteins like L1, L11, S3 and S4 are radiolabeled. L11, S3 and S4 are radiolabeled specifically as demonstrated by photo-incorporation experiments with isotopically diluted [3H]chloramphenicol or by comparison of the results obtained here with reversible experiments performed by the isotopic dilution method. When the D-erythro diastereoisomer of chloramphenicol is photo-incorporated into the bacterial ribosome, proteins are radiolabeled only in a non-specific way. These results show that this material could be used as an efficient scavenger.

When finally D-threo [3H]chloramphenicol is photo-incorporated in the presence of a large amount of the D-erythro diastereoisomer, the radiolabeling pattern obtained for the proteins is quite different from that expected: while L11 is still labeled fairly extensively, L27 is the most radiolabeled protein found.