Northern lights assay: a versatile method for comprehensive detection of DNA damage.

DNA damage assays have various limitations in types of lesions detected, sensitivity, specificity and samples that can be analyzed. The Northern Lights Assay (NLA) is based on 2D Strandness-Dependent Electrophoresis (2D-SDE), a technique that separates nucleic acids based on length, strandness, structure and conformation changes induced by damage. NLA is run on a microgel platform in 20-25 min. Each specimen is analyzed in pairs of non-digested DNA to detect single- and double-stranded breaks (DSBs) and Mbo I-digested DNA to detect other lesions. We used NLA to evaluate DNA in solution and isolated from human cells treated with various genotoxic agents. NLA detected and distinguished between single- and DSBs, interstrand and intrastrand DNA crosslinks, and denatured single-stranded DNA. NLA was sufficiently sensitive to detect biologically relevant amount of DNA damage. NLA is a versatile, sensitive and simple method for comprehensive and simultaneous analysis of multiple types of damage, both in purified DNA and in DNA isolated from cells and body fluids. NLA can be used to evaluate DNA quality in biosamples, monitor complex molecular procedures, assess genotoxicity, diagnose genome instability, facilitate cancer theranostics and in basic nucleic acids research.

Intranasal bioavailability of diazepam in sheep correlated to rabbit and man.

The purposes of the present study were to estimate the nasal bioavailability of diazepam in sheep and to compare this to earlier results in rabbits and humans. Additional, to compare the absorption during various initial periods in the two animal models and man, due to the importance of early absorption in emergency treatment. In a cross-over design, diazepam was nasally administered (7 mg) and intravenously (3 mg), respectively, to six sheep. Diazepam was solubilised in polyethylene glycol 300 in the nasal formulation. The mean nasal bioavailability, t(max) and C(max) were 15% (S.D.+/-8), 5 min (S.D.+/-3) and 934 ng/ml (S.D.+/-593), respectively. Sheep bioavailability was lower than rabbit 54% (P<0.001) and man 34% (P<0.05). In conclusion, the nasal absorption of diazepam was found to be fast, indicating the potential of nasal delivery in acute treatment. The initial (30 min) nasal bioavailability (30 min) for sheep and rabbit is a factor of 2.3 lower and 1.6 higher than man, respectively. The correlation of bioavailability was not optimal between sheep, man and rabbit with differences both in relation to extend and rate.