ABSTRACT
AIMS: Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a widely used biomarker of oxidative stress. However, variability between chromatographic and ELISA methods hampers interpretation of data, and this variability may increase should urine composition differ between individuals, leading to assay interference. Furthermore, optimal urine sampling conditions are not well defined. We performed inter-laboratory comparisons of 8-oxodG measurement between mass spectrometric-, electrochemical- and ELISA-based methods, using common within-technique calibrants to analyze 8-oxodG-spiked phosphate-buffered saline and urine samples. We also investigated human subject- and sample collection-related variables, as potential sources of variability. RESULTS: Chromatographic assays showed high agreement across urines from different subjects, whereas ELISAs showed far more inter-laboratory variation and generally overestimated levels, compared to the chromatographic assays. Excretion rates in timed 'spot' samples showed strong correlations with 24 h excretion (the 'gold' standard) of urinary 8-oxodG (rp 0.67-0.90), although the associations were weaker for 8-oxodG adjusted for creatinine or specific gravity (SG). The within-individual excretion of 8-oxodG varied only moderately between days (CV 17% for 24 h excretion and 20% for first void, creatinine-corrected samples). INNOVATION: This is the first comprehensive study of both human and methodological factors influencing 8-oxodG measurement, providing key information for future studies with this important biomarker. CONCLUSION: ELISA variability is greater than chromatographic assay variability, and cannot determine absolute levels of 8-oxodG. Use of standardized calibrants greatly improves intra-technique agreement and, for the chromatographic assays, importantly allows integration of results for pooled analyses. If 24 h samples are not feasible, creatinine- or SG-adjusted first morning samples are recommended.
Subject(s)
Artifacts , Deoxyguanosine/analogs & derivatives , Urinalysis/standards , 8-Hydroxy-2'-Deoxyguanosine , Adult , Buffers , Deoxyguanosine/analysis , Deoxyguanosine/urine , Female , Head and Neck Neoplasms/urine , Humans , Male , Middle Aged , Reference Standards , Reproducibility of Results , Sodium Chloride , Solutions , Young AdultABSTRACT
Treatment of [Me(4)N](2)[PhP(CH(2)CH(2)S)(2)] with [Mo(CO)(3)(NCMe)(3)] affords the reactive intermediate [Me(4)N](2)[Mo(CO)(3){PhP(CH(2)CH(2)S)(2)}] (1), which undergoes oxidation to afford [Mo{PhP(CH(2)CH(2)S)(2)}(2)] (2). Reaction of 1 with a variety of dichloroalkanes produces [Mo(CO)(3){c-PhP(CH(2)CH(2)S)(2)X}] (X = CH(2)CH(2), CH(2)CH(2)CH(2), CH(2)CHMe or CH(2)CH(OH)CH(2)). The structure of [Mo(CO)(3){c-PhP(CH(2)CH(2)S)(2)CH(2)CH(2)}] (3) has been established by X-ray crystallography and consists of a Mo(CO)(3) fragment facially coordinated by the tridentate c-PhP(CH(2)CH(2)S)(2)CH(2)CH(2) ligand. Reaction of 3 with bromine affords seven-coordinate [Mo(CO)(2){c-PhP(CH(2)CH(2)S)(2)CH(2)CH(2)}Br(2)] (7), the X-ray crystal structure of which reveals a carbonyl-capped octahedral geometry. Treatment of 3 with sulfur results in loss of the Mo(CO)(3) fragment and isolation of c-PhPS(CH(2)CH(2)S)(2)CH(2)CH(2) (8), the X-ray structure of which shows a nine-membered ring with the phosphorus center bearing phenyl and sulfide substituents. Reduction of 8 with sodium naphthalenide affords the parent ligand c-PhP(CH(2)CH(2)S)(2)CH(2)CH(2). Crystal data: 2, C(20)H(26)MoP(2)S(4), triclinic P&onemacr;, a = 8.105(3) Å, b = 8.263(3) Å, c = 17.663(4) Å, alpha = 100.29(2) degrees, beta = 99.78(2) degrees, gamma = 98.81(2) degrees, Z = 2; 3, C(15)H(17)MoO(3)PS(2), monoclinic P2(1)/n, a = 9.600(3) Å, b = 15.594(5) Å, c = 11.335(3) Å, beta = 93.01(2) degrees, Z = 4; 7, C(14)H(17)Br(2)MoO(2)PS(2), monoclinic P2(1)/c, a = 17.039(3) Å, b = 8.686(2) Å, c = 12.466(3) Å, beta = 100.52(2) degrees, Z = 4; 8, C(12)H(17)PS(3), monoclinic P2(1), a = 6.651(4) Å, b = 7.313(2) Å, c = 14.687(9) Å, beta = 101.62(3) degrees, Z = 2.
