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Oxidative stress caused by chronic lung inflammation in patients with cystic fibrosis (CF) and chronic lung infection with Pseudomonas aeruginosa is characterized by the reactive oxygen species (ROS) liberated by polymorphonuclear leukocytes (PMNs). We formulated the hypothesis that oxidation of the bacterial DNA by ROS presents an increased risk for the occurrence of hypermutable P. aeruginosa. The occurrence of hypermutable P. aeruginosa isolates was investigated directly in the sputum of 79 CF patients and among 141 isolates collected from 11 CF patients (10 to 15 isolates/patient) collected from the 1st and up to the 25th year of their chronic lung infection. The level of oxidized guanine moiety 8-oxo-2-deoxyguanosine (8-oxodG), which is a frequently investigated DNA oxidative lesion, was measured. Hypermutable P. aeruginosa isolates were found in the sputum bacterial population of 54.4% of the CF patients. The earliest mutator P. aeruginosa isolates were found after 5 years from the onset of the chronic lung infection, and once they were present in the CF lung, the prevalence increased with time. The hypermutable isolates were significantly more resistant to antipseudomonal antibiotics than nonhypermutable isolates (P < 0.001). The level of 8-oxodG/10 6 deoxyguanosine (dG) was significantly higher in hypermutable P. aeruginosa isolates (87 ؎ 38) than in nonhypermutable P. aeruginosa isolates (59.4 ؎ 17) (P ‫؍‬ 0.02), and an increase to 86.84 from 21.65 8-oxodG/10 6 dG was found after exposure of the reference strain PAO1 to activated PMNs. Our results suggest that the chronic PMN inflammation in the CF lung promotes oxidative stress and is associated with the occurrence of hypermutable bacteria in the lung. The hypermutable phenotype can associate with mutations that confer adaptation of the bacteria in the lung and persistence of the infection.

Objective-To examine the role of peak bone mass and subsequent postmenopausal bone loss in the development of osteoporosis and the reliability of identifying women at risk from one bone mass measurement and one biochemical assessment of the future bone loss.Design-Population based study. Setting-Outpatient clinic for research into osteoporosis.Subjects-178 healthy early postmenopausal women who had participated in a two year study in 1977. 154 of the women underwent follow up examination in 1989, of whom 33 were excluded because of diseases or taking drugs known to affect calcium metabolism.Main outcome measures-Bone mineral content of the forearm and values of biochemical markers of bone turnover.Results-The average reduction in bone mineral content during 1977-89 was 20%, but the fast losers had lost 10-0% more than had the slow loser group (mean loss 26-6% in fast losers and 16-6% in slow losers; p<0-001). Prediction of future bone mineral content using baseline bone mineral content and estimated rate of loss gave results almost identical with the actual bone mineral content measured in 1989. Seven women had had a Colies' fracture and 20 a spinal compression fracture. The group with Colies' fracture had low baseline bone mineral content (34.7 (95% confidence interval 31-3 to 38-1) units v 39*4 (38-1 to 40.8) units in women with no fracture) whereas the group with spinal fracture had a normal baseline bone mineral content (38-1 (35.0 to 41-1) units) but an increased rate of loss (-2-4 (-3 5 to -1-3)%/year v -1-8 (-2-1 to -1-5)%/year in women with no fracture).Conclusions-One baseline measurement of bone mass combined with a single estimation of the rate of bone loss can reliably identify the women at menopause who are at highest risk of developing osteoporosis later in life. The rate of loss may have an independent role in likelihood of vertebral fracture.

An enzyme-linked immunosorbent assay (ELISA) for measuring type I collagen degradation products in urine &lt; 3 h was evaluated. The measuring range was 0.5-10.5 mg/L with a detection limit of 0.2 mg/L. Within-run and total CVs were 5.3% and 6.6%, respectively. Analytical recovery averaged 100%. The mean (+/- SD) concentrations in urine samples from a healthy premenopausal population (n = 102) were 250 +/- 110 mg/mol creatinine (Cr). A group of healthy postmenopausal women (n = 410) gave a mean value of 416 +/- 189 mg/mol Cr. Values obtained in the ELISA correlated well (r = 0.83) to HPLC values for the established bone resorption marker deoxypyridinoline (n = 214), slightly better than the correlation to hydroxyproline measurements (r = 0.78, n = 421). We conclude that the assay described here presents a useful tool for further elucidating the importance of type I collagen degradation products in urine.

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Mutations in the CSA and CSB genes cause Cockayne syndrome, a rare inherited disorder characterized by UV sensitivity, severe neurological abnormalities, and progeriod symptoms. Both gene products function in the transcription-coupled repair (TCR) subpathway of nucleotide excision repair (NER), providing the cell with a mechanism to remove transcription-blocking lesions from the transcribed strands of actively transcribed genes. Besides a function in TCR of NER lesions, a role of CSB in (transcription-coupled) repair of oxidative DNA damage has been suggested. In this study we used mouse models to compare the effect of a CSA or a CSB defect on oxidative DNA damage sensitivity at the levels of the cell and the intact organism. In contrast to CSB ؊/؊ mouse embryonic fibroblasts (MEFs), CSA ؊/؊ MEFs are not hypersensitive to gamma-ray or paraquat treatment. Similar results were obtained for keratinocytes. In contrast, both CSB ؊/؊ and CSA ؊/؊ embryonic stem cells show slight gamma-ray sensitivity. Finally, CSB ؊/؊ but not CSA ؊/؊ mice fed with food containing di(2-ethylhexyl)phthalate (causing elevated levels of oxidative DNA damage in the liver) show weight reduction. These findings not only uncover a clear difference in oxidative DNA damage sensitivity between CSA-and CSB-deficient cell lines and mice but also show that sensitivity to oxidative DNA damage is not a uniform characteristic of Cockayne syndrome. This difference in the DNA damage response between CSA-and CSBdeficient cells is unexpected, since until now no consistent differences between CSA and CSB patients have been reported. We suggest that the CSA and CSB proteins in part perform separate roles in different DNA damage response pathways.

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clinicaltrials.gov Identifier: NCT01657162.