Air quality effects of traffic in a canyon-like street (Falmouth, U.K.).

It has been suggested that in relation to air quality impacts, roads with low (<20000 vpd) traffic flow need not be considered as significant. This study examines this suggestion more closely by comparing real-time monitoring of traffic related pollutants (NO2, PM10 and PAH) at two sites (including a 'canyon-street') in Falmouth, Cornwall in relation to traffic flow. For comparison, real-time monitoring data for NO2 and PM10 is also taken from a well ventilated site in Camelford, Cornwall. The data obtained suggest that roads with traffic flow considerably lower than 20000 vpd can give rise to pollutant levels which have implications for human health. The application of simple linear regression techniques to the data suggests that under certain conditions simple estimates can be made in relation to likely traffic-related air quality effects in canyon-like streets.

Intravascular ultrasound predictors of restenosis after percutaneous transcatheter coronary revascularization.

OBJECTIVES: This study sought to evaluate preintervention and postintervention intravascular ultrasound studies for potential predictors of angiographic restenosis and to use ultrasound predictors of restenosis to enhance our understanding of the pathophysiology of the restenosis disease process. BACKGROUND: Restenosis remains the major limitation of percutaneous transcatheter coronary revascularization. Although its mechanisms remain incompletely understood, numerous studies have identified some of the clinical, anatomic and procedural risk factors for restenosis. Intravascular ultrasound imaging of target lesions before and after catheter-based treatment consistently demonstrates more target lesion calcium, more extensive reference segment atherosclerosis, smaller final lumen dimensions, significant residual plaque burden and a greater degree of tissue trauma than is evident by angiography. METHODS: Intravascular ultrasound studies were performed in 360 nonstented native coronary artery lesions (final diameter stenosis 18 +/- 11%) in 351 patients for whom follow-up angiographic data were available 6.4 +/- 3.6 months later. Hospital charts were reviewed, and qualitative and quantitative coronary angiographic and intravascular ultrasound analyses were performed by independent core laboratories. Four dependent angiographic end points were tested: restenosis as a binary definition (> or = 50% diameter stenosis at follow-up) was the primary end point; follow-up diameter stenosis, late lumen loss and follow-up minimal lumen diameter were the secondary end points. RESULTS: Reference vessel size, the preintervention quantitative coronary angiographic assessment of lesion severity and the postintervention intravascular ultrasound cross-sectional measurements predicted the late angiographic results. In particular, the intravascular ultrasound postintervention cross-sectional narrowing (plaque plus media cross-sectional area divided by external elastic membrane cross-sectional area) predicted the primary end point (restenosis) and two of the three secondary end points (follow-up diameter stenosis and late lumen loss) and was therefore the most consistent predictor of restenosis. CONCLUSIONS: Intravascular ultrasound variables are more powerful and consistent predictors of angiographic restenosis than currently accepted clinical or angiographic risk factors.

Mechanisms of lumen enlargement after excimer laser coronary angioplasty. An intravascular ultrasound study.

BACKGROUND: The mechanisms of excimer laser coronary angioplasty (ELCA) have never been studied in human coronary arteries in vivo. METHODS AND RESULTS: ELCA was used to treat 202 lesions in 190 patients. Forty-nine lesions in 48 patients were studied by use of sequential (before and after ELCA and after adjunctive device therapy) intravascular ultrasound (IVUS). External elastic membrane (EEM), lumen, and plaque+media (P+M = EEM-lumen) cross-sectional areas (CSAs) and lesion arcs of calcium were measured before and after ELCA and after adjunct device use. Lumen improvement after ELCA (1.4 +/- 0.5 to 2.7 +/- 0.8 mm2) was the result of both tissue ablation (decrease in P+M CSA from 16.8 +/- 7.1 to 15.9 +/- 6.7 mm2, P < .0001) and vessel expansion (increase in EEM CSA from 18.2 +/- 7.1 to 18.6 +/- 6.8 mm2, P = .0245), with no change in calcium. The decrease in P+M CSA was 39% of the CSA of the laser catheter used. Dissections were present in 39% of lesions, 84% within superficial calcium; fibrocalcific deposits developed a "fragmented" appearance. CONCLUSIONS: ELCA increased lumen CSA by both atheroablation and vessel expansion without calcium ablation. Superficial fibrocalcific deposits developed a characteristic fragmented appearance. These findings support both photoablation and forced vessel expansion as mechanisms of lumen enlargement and plaque dissection after ELCA.

A simple method for the characterization of photoproducts from DNA applied to the cis-syn thymine dimer.

A method for the unambiguous characterization of DNA photoproducts has been developed. It does not require radio-labelled DNA, or specialized techniques. In the preliminary step, UV-irradiated DNA is hydrolysed to its constituent bases and photoproducts. The photoproducts are then separated from nucleic acid bases using low pressure ion-exchange chromatography on a Dowex 1 x 8 200-400, and an Amberlite CG-50-H+ column. Further separation and purification of photoproducts is carried out on the HPLC Whatman Partisil ODS2 column, using 15% MeOH. The procedure is simple, reproducible and versatile.