Mutagenic and DNA repair activity in traffic policemen: a case-crossover study

Background

Emissions from vehicles are composed of heterogeneous mixtures of hazardous substances; several pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) are amongst the most dangerous substances detected in urban monitoring. A cohort of traffic policemen usually occupationally exposed to PAHs present in the urban environment were examined in order to assess the mutagenicity and DNA capacity repair.

Methods

Seventy-two urban traffic policemen working in Catania’s metropolitan area were enrolled in the study. Two spot urine samples were collected from each subject during the whole working cycle as follows: sample 1 (S1), pre-shift on day 1; sample 2 (S2) post-shift on day 6. 1-hydroxypyrene (1-OHP) was measured to serve as an indirect exposure indicator. Urinary mutagenic activity was assessed through the plate incorporation pre-incubation technique with S9, using YG1024 Salmonella typhimurium strain over-sensitive to PAH metabolite. Concentrations of urinary 8-oxodG were measured using liquid chromatography tandem mass spectrometry.

Results

As regards the exposure to PAHs, results highlighted a statistically significant difference (p?<?0.001) between pre-shift on day 1 and post-shift on day 6 levels. Mutagenic activity was detected in 38 (66%) workers on S1 and in 47 (81%) on S2. Also 8-oxodG analysis showed a statistically significant difference between S1 and S2 sampling.

Conclusions

This study demonstrated that occupational exposure to pollutants from traffic emission, assessed via 1-OHP measurements in urine, may lead to DNA repair and mutagenic activity, in line with other studies.

     

Social Factors Associated with Non-initiation and Cessation of Predominant Breastfeeding in a Mother–Child Cohort in Spain

Objective The aim of the study was to identify factors associated with non-initiation and cessation of predominant breastfeeding (PBF) in a mother–child cohort from Spain. Materials and Methods The analysis included 2195 mother-infant from birth to 14 months post- delivery recruited between 2004 and 2008. Maternal characteristics were collected during the pregnancy. Lactation data were obtained at 6 and 14 months after delivery. PBF was defined as intake of breast milk plus liquids like juices or water. The PBF cessation was calculated using the date that women started PBF and the date that she reported to start giving infant formula and/or food. The relationship between maternal variables and PBF initiation and cessation was modeled using logistic and Cox proportional hazards regression analysis. Results The prevalence of PBF at hospital discharge was 85.3, 53.4% at 3 months, 46.1% at 4 months and 7.2% at 6 month. Only two women continued PBF at 12 months and none at 14 months. The initiating of PBF was associated with higher levels of maternal education, being a first-time mother and worked in a non-manual occupation. Higher level of physical activity, not smoking and having a healthy BMI, were also positively associated with PBF initiation. PBF cessation was higher in young, obese women, who had had complications during the pregnancy, and who had lower levels of education and smoked. The employment status of women, in week 32 of pregnancy and also in month 14 post-delivery, determined likelihood of PBF cessation. Conclusions Healthier habits and education positively influenced PBF initiation and duration. Decrease in PBF duration rates in Spain can be interpreted in part as a consequence of women returning to work.     

Enhancement of ultrasound-induced apoptosis and cell lysis by echo-contrast agents

To determine the effects of echo-contrast agents (ECAs) on ultrasound (US)-induced apoptosis and cell lysis, human myelomonocytic lymphoma U937 cells in suspension were exposed to 1 MHz continuous waves US for 1 min at an intensity of 0.5, 1.0, 2.0 or 4.0 W/cm(2) with or without non-shell type ECA, Levovist (2 mg/ml), and shell type, Optison (1 microl/ml) or YM454 (1 microl/ml). Levovist minimally enhanced the US-induced apoptosis at 1.0 W/cm(2) while Optison and YM454 did at 2.0 and 4.0 W/cm(2), as detected by flow cytometry. Cell lysis was also augmented when Levovist was combined with US at 2.0 W/cm(2), and when Optison was combined with US at 2.0 and 4.0 W/cm(2). YM454 showed the highest rate of enhanced cell lysis at 1.0, 2.0 and 4.0 W/cm(2). Therefore, this study shows that Optison and YM454 are effective in augmenting the US-induced cell killing, but not Levovist. Another result indicates that cavitation plays a role in the augmented effects and that inertial cavitation appears necessary for Optison and YM454 to effect their actions. In addition, results show that the rate of apoptosis is lower in the presence of ECAs with higher free radical scavenging activity, suggesting a possible role for free radicals in apoptosis. These findings suggest that some ECAs have potential to be adjuncts in cases wherein augmented US-induced cell killing is needed, such as in cancer therapy with US.