Search

Rapid advances in the understanding of genomic variation affecting drug responses, and the development of multiplex assay technologies, are converging to form the basis for new in vitro diagnostic assays. These molecular diagnostic assays are expected to guide the therapeutic treatment of many diseases, by informing physicians about molecular subtypes of disease that require differential treatment, which drug has the greatest probability of effectively managing the disease, and which individual patients are at the highest risk of experiencing adverse reactions to a given drug therapy. This article reviews some of the relative strengths and limitations of the most widely used technologies and platforms for such assays. [ABSTRACT FROM AUTHOR]

The mutational specificity of -methylnitrosourea (MNU), nitrosoguanidine (MNNG), methyl methanesulfonate (MMS), sodium azide (NaN) 4-nitroquinoline oxide (4NQO), benzo (BP), nitrofurantoin (NT), aflatoxin B (AFB adriamycin (ADM) and UVA-activated angelicin in Salmonella typhimurium strain TAIOO has been examined using allele-specific oligonudeotide hybridization and DNA sequence analyses. These ten mutagens produced five unique dasses of reversion spectra, distinct from spontaneous, or the previously characterized 5-azacytldine, ultraviolet light WV), 8-methoxypsoralen plus UVA (PUVA) and 60 mutation spectra. For example, 90% of MNU and MNNG induced mutations in strain TAIOO revertants were G:C-A:T transitions with the majority (82%) occurring in the first position of the CCC codon. In contrast, NaN preferentially induced G:C- transitions at the second codon position (78%). Although MMS, NQO, BP, NF, ADM and AFB induced primarily G:C-T:A transversions (73–86%), these mutagens fall into two dasses based on site preference: NF and AFB yielded almost exclusively position two transversion.s (69-78%) whereas ADM, NQO, BP and MMS exhibited a two-fold preference for site 2 over site 1 (on average 52% versus 22%). Angelicin photomutagenesis resulted in the recovery of G:C-A:T and G:C-T:A mutations at both codon positions in roughly equal proportions (˜20-25% each). Approximately 1% of the mutagen-induced revertants occurred via extragenic tRNA suppressor mutations, while 1% were multiple (usually tandem double) base substitutions. Ultraviolet mutagenesis experiments demonstrated that tandem base substitutions are promoted by pKM1O1-encoded mucAB gene products. A comparison of the mutagenic specificity derived for several carcinogens in with the responses of several eukaryotic gene targets (e.g. ) revealed a high concordance between these targets. Thus, the locus provides a rapid, simple system for determining base substitution specificity and for studying mechanisms of mutagenesis. [ABSTRACT FROM PUBLISHER]

An antiserum against α-amino-(4-hydroxy-6-benzothiazolyl)propionic acid (AHBP), a major product obtained after hydriodic acid hydrolysis of pheomelanin, was raised in rabbits immunized with AHBP coupled to bovine serum albumin (BSA). The antiserum was used to develop a radioimmunoassay (RIA) to AHBP. The limit of detection of the RIA is 0.1 ng of AHBP. The antiserum does not crossreact with other major hydriodic acid degradation products, and the assay has been used to estimate the amounts of AHBP in synthetic and natural melanins. [ABSTRACT FROM AUTHOR]

The Salmonella typhimurium tester strains TA104 and TA102 were developed primarily to aid in the detection of oxidative mutagens and other agents that react preferentially with AT base pairs. Reversion to prototrophy of strains harboring the hisG428 ochre allele can occur by (i) any of seven single base substitutions or (ii) several tandem double base substitutions at the ochre codon, (iii) in-frame deletions removing all or part of the ochre codon or (iv) mutations at several distinct tRNA extragenic suppressor loci. We have used allele-specific oligonucleotide probes and DNA sequence analysis to characterize 625 revertants of strain TA104 (hisG428, rfa, ΔuvrB/pKM101) arising spontaneously or after treatment with methyl methanesulfonate, glyoxal, streptonigrin or angelicin with UVA radiation. The reversion profiles obtained from these analyses distinguished readily each of the mutagentreated populations from one another and from spontaneously derived revertants. Both GC and AT base pairspecific revertants were observed. Molecular analyses of S.typhimurium hisG428 revertants permitted rapid assessment of base pair substitution specificity of mutagens, especially the detection of AT base pair substitutions not recovered in strains carrying the complementary hisG46 allele. [ABSTRACT FROM AUTHOR]

Focuses on the Salmonella typhimurium LT7 and LT2 strains carrying the imp operon on ColIa. Role of the transmissible plasmid ColIa in original isolates of Salmonella typhimurium LT7; Acquisition of ColIa and imp by LT2 strain recipients; Use of Salmonella typhimurium as a model genetic organism.