Acute ozone-induced differential gene expression profiles in rat lung

Ozone is an oxidant gas that can directly induce lung injury. Knowledge of the initial molecular events of the acute O3 response would be useful in developing biomarkers of exposure or response. Toward this goal, we exposed rats to toxic concentrations of O3 (2 and 5 ppm) for 2 hr and the molecular changes were assessed in lung tissue 2 hr postexposure using a rat cDNA expression array containing 588 characterized genes. Gene array analysis indicated differential expression in almost equal numbers of genes for the two exposure groups: 62 at 2 ppm and 57 at 5 ppm. Most of these genes were common to both exposure groups, suggesting common roles in the initial toxicity response. However, we also identified the induction of nine genes specific to 2-ppm (thyroid hormone-beta receptor c-erb-A-beta; and glutathione reductase) or 5-ppm exposure groups (c-jun, induced nitric oxide synthase, macrophage inflammatory protein-2, and heat shock protein 27). Injury markers in bronchoalveolar lavage fluid (BALF) were used to assess immediate toxicity and inflammation in rats similarly exposed. At 2 ppm, injury was marked by significant increases in BALF total protein, N-acetylglucosaminidase, and lavageable ciliated cells. Because infiltration of neutrophils was observed only at the higher 5 ppm concentration, the distinctive genes suggested a potential amplification role for inflammation in the gene profile. Although the specific gene interactions remain unclear, this is the first report indicating a dose-dependent direct and immediate induction of gene expression that may be separate from those genes involved in inflammation after acute O3 exposure.     

Breast cancer incidence in women prenatally exposed to maternal cigarette smoke

BACKGROUND: Clinical studies show that maternal cigarette smoking reduces pregnancy estrogen levels. Women prenatally exposed to maternal cigarette smoke may, therefore, have a lower breast cancer risk because the fetal mammary gland's exposure to maternal estrogen is decreased. Associations between prenatal maternal cigarette smoke exposure and breast cancer, however, have not been observed in previous case-control studies that relied on exposure assessment after the onset of cancer. At the start of this study, cigarette smoking history was obtained directly from the mother. METHODS: The National Cooperative DES Adenosis project was a follow-up study of health outcomes in women prenatally exposed to diethylstilbestrol (DES). At the start of the study, women's mothers provided information about cigarette smoking habits during the time they were pregnant with the study participant. In the current study, the breast cancer rates are compared among 4031 women who were or were not prenatally exposed to maternal cigarette smoke. The resultant relative rate (RR) is adjusted for potential confounding by other breast cancer risk factors using Poisson regression modeling. RESULTS: Fetal exposure to maternal cigarette smoke appeared to be inversely associated with breast cancer incidence (RR = 0.49; 95% confidence interval [CI] = 0.24-1.03). The inverse association was more apparent among women whose mothers smoked 15 cigarettes or fewer per day than among daughters of heavier smokers. There were, however, too few cases to precisely estimate a possible dose-response relationship. CONCLUSION: These results support the hypothesis that in utero exposure to maternal cigarette smoke reduces breast cancer incidence.     

Inhibition of DNA synthesis, independent of DNA adduct formation, by benzo[a]pyrene diol epoxide in mammalian cells

Treatment of SV40-infected CV-1 cells with the ultimate carcinogenanti-benzo[a]pyrene diol epoxide (BPDE) at 1 x 10 ^–4 mg/mlor higher reduced the rate of viral DNA synthesis to an extentdependent on the BPDE concentration; similar reductions in cellularDNA synthesis were produced in infected and uninfected cells.Treatment of cells with BPDE, followed by removal of BPDE, atvarious times before infection with SV40 gave the same results.Recovery or partial recovery of DNA synthesis occurred whenthe BPDE concentration was below 6 x 10 ^–4 mg/ml; at higherconcentrations the cells were killed. Simultaneously replicatingviral DNA's from viruses infecting the same cells before andafter BPDE treatment of the cells exhibited the same reducedrate of synthesis. The evidence indicates that covalent adductsin viral DNA are not responsible for its reduced replicationrate; moreover, it is probable that an insignificant numberof adducts is produced in intracellular viral DNA at BPDE concentrationsthat do not kill CV-1 cells. Rather, it appears likely thatBPDE inhibits viral DNA synthesis by attacking cellular DNAor non-DNA targets. Caution is therefore required in relatingthe effects of BPDE and other carcinogens to DNA adduct formation.     

DNA mapping using microfluidic stretching and single-molecule detection of fluorescent site-specific tags

We have developed a rapid molecular mapping technology--Direct Linear Analysis (DLA)--on the basis of the analysis of individual DNA molecules bound with sequence-specific fluorescent tags. The apparatus includes a microfluidic device for stretching DNA molecules in elongational flow that is coupled to a multicolor detection system capable of single-fluorophore sensitivity. Double-stranded DNA molecules were tagged at sequence-specific motif sites with fluorescent bisPNA (Peptide Nucleic Acid) tags. The DNA molecules were then stretched in the microfluidic device and driven in a flow stream past confocal fluorescence detectors. DLA provided the spatial locations of multiple specific sequence motifs along individual DNA molecules, and thousands of individual molecules could be analyzed per minute. We validated this technology using the 48.5 kb lambda phage genome with different 8-base and 7-base sequence motif tags. The distance between the sequence motifs was determined with an accuracy of +/-0.8 kb, and these tags could be localized on the DNA with an accuracy of +/-2 kb. Thus, DLA is a rapid mapping technology, suitable for analysis of long DNA molecules.     

Environmental tobacco smoke and breast cancer incidence

To evaluate whether environmental tobacco smoke (ETS) influences breast cancer incidence, data from a population-based case-control study were analyzed. Respondents with available ETS information assessed by in-person questionnaires included 1356 newly diagnosed cases and 1383 controls. Relative to nonsmokers who reported no residential ETS exposure throughout the life course, the odds ratios (OR) for breast cancer were not substantially elevated in relation to ETS exposure, active smoking, or a joint measure of active and passive smoking (OR, 1.15, 95% CI, 0.90, 1.48). An increased OR, however, was noted among nonsmokers who lived with a smoking spouse for over 27 years (2.10, 95% CI, 1.47, 3.02), although no dose-response was evident. Also, among women with hormone-receptor-positive tumors only, the OR for both active and passive smoking was increased (1.42 for ER+ PR+, 95% CI, 1.00, 2.00). Our data suggest that if there is an effect for ETS on breast cancer, that effect is restricted to selected subgroups of women, such as those with long-term exposure from a smoking spouse.