Influence of ozone on traffic-related particulate matter on the generation of hydroxyl radicals through a heterogeneous synergistic effect

Epidemiologic studies suggest that ozone (O(3)) and airborne particulate matter (PM) can interact causing acute respiratory inflammation and other respiratory diseases. Recent studies investigated the hypothesis that the effects of air pollution caused by O(3) and PM are larger than the effect of these two pollutants individually. We investigated the hypothesis that ozone and traffic-related PM (PM(10) and PM(2.5), diesel and gasoline exhaust particles) interact synergistically to produce increasing amounts of highly reactive hydroxyl radicals (HO) in a heterogeneous aqueous mixture at physiological pH. Electron paramagnetic resonance (EPR) and spin trapping were used for the measurements. Results showed that HO radicals are generated by the catalytic action of PM surface area with ozone and that EPR peak intensities are two to three times higher compared to PM samples without ozone. Incubation of the nucleoside 2'-deoxyguanosine (dG) in aqueous mixtures of ozone and PM at pH 7.4 resulted in the hydroxylation at C(8) position of dG. The formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) showed a 2-2.5-fold increase over control (PM without O(3)). These results suggest that PM and O(3) act synergistically generating a sustained production of reactive HO radicals. Partitioning of O(3) into the particle phase depends on the concentration, hygroscopicity and particle size.     

An Overview of Standards and Related Technology in Web Services

The Internet is revolutionizing business by providing an affordable and efficient way to link companies with their partners as well as customers. Nevertheless, there are problems that degrade the profitability of the Internet: closed markets that cannot use each other's services; incompatible applications and frameworks that cannot interoperate or built upon each other; difficulties in exchanging business data. Web Services is a new paradigm for e-business that is expected to change the way business applications are developed and interoperate. A Web Service is a self-describing, self-contained, modular application accessible over the web. It exposes an XML interface, it is registered and can be located through a Web Service registry. Finally, it communicates with other services using XML messages over standard Web protocols. This paper presents the Web Service model and gives an overview of existing standards. It then sketches the Web Service life-cycle, discusses related technical challenges and how they are addressed by current standards, commercial products and research efforts. Finally it gives some concluding remarks regarding the state of the art of Web Services.     

Effect of sex and age on bone mass, body composition and fuel metabolism in humans

The mechanism(s) governing the gain of upper-body fat and its relationship to the decrease in bone mass with age is still unclear. Therefore, four groups of subjects matched for weight, height, and body mass index (n = 119; 60 women, 59 men), but differing in age (above and below 50 y) and sex were investigated using dual energy x-ray absorptiometry (DXA) to assess body composition (bone, lean, and fat mass as well as its distribution) and indirect calorimetry to determine resting fuel metabolism. Fat mass of trunk and arms (P < 0.01), but not legs, increased with advancing age in males, resulting in a continuous increase in the ratio of upper- to lower-body fat (r = 0.45, P < 0.001). In contrast, total fat mass remained stable in women, irrespective of menopause, but a redistribution of fat occurred with advancing age (r = 0.43, P < 0.001), resulting in a higher upper- to lower-body fat ratio (P < 0.05) in older than in younger women. Total lean soft-tissue mass of all segments of the body was greater in men than in women irrespective of age (P < 0.001), and lower in the older groups than in the younger ones irrespective of sex. In males, but not females, lean soft-tissue mass in arms and legs decreased (r = 0.57, P < 0.001), whereas the ratio of total fat to lean soft-tissue mass increased (r = 0.53, P < 0.001) with age. Bone mineral content correlated with total body fat in both groups of women and in young males (r > 0.5, P < 0.001), but not in older males. With advancing age, the proportion of lean soft-tissue mass occupied by total skeleton declined in women (n = 59, P < 0.001), but remained stable in males. Resting energy expenditure decreased with age in both sexes. Protein and carbohydrate oxidation were similar in all four groups of subjects. Total fat oxidation and fat oxidation per kilogram of lean soft-tissue mass decreased with age (r > 0.36, P < 0.01) in males, but not in females, whereas it increased with increasing fat mass in females (r > 0.32, P < 0.03), but not in males. In contrast, fat oxidation per kilogram of fat mass decreased with fat mass in males (r = 0.61, P < 0.001), but not in females. Our results suggest that aging affects body composition and fuel metabolism differently in each gender, leading to reduced fat oxidation and accumulation of upper-body fat with loss of striated muscle in men, and to an increased ratio of upper- to lower-body fat and bone loss in women, the latter depending on fat mass.     

Impact of hydration status on body composition as measured by dual energy X-ray absorptiometry in normal volunteers and patients on haemodialysis

To evaluate the influence of hydration status on the estimation of body composition using dual-energy X-ray absorptiometry (DXA), six normal volunteers and seven patients on maintenance haemodialysis were investigated using two different DXA machines (Lunar DPX, Hologic QDR 1000/W). Normal volunteers were studied (Hologic QDR 1000/W) before and 1 h after ingestion of breakfast, lunch and dinner (drinking various amounts of liquids at each meal, 0.5-2.4 kg). Whereas bone mineral content and body fat mass did not change, lean body mass of the trunk increased as a consequence of the meals. Conversely in patients on haemodialysis (Lunar DPX), lean body mass decreased in all segments of the body as a consequence of removal of 0.9-4.4 kg of salt-containing fluid by haemodialysis (trunk 61%, legs 30%, arms 5.5% and rest of the body 3.5%), whereas bone mineral content and body fat mass remained unchanged. However, this finding(s) did not hold true in one particular patient with bilateral hip prostheses. Measurement of body composition in eight normal volunteers on the same day with both machines showed similar results for lean and fat mass, whereas bone mineral content was found to be 17% higher using the Lunar DPX. In summary, in centres where both machines are available, follow-up of one individual patient should always be performed using the same equipment. In addition, hydration status and food intake must be taken into account when repetitive measurements of lean body mass are performed in the same patient.