The activities of 210Po and 210Pb in cigarette smoked in Tunisia.

In this study, the activity concentration of polonium 210 in cigarette for Tunisian consumers was investigated by alpha spectrometry. After chemical digestion of tobacco, 210Po was extracted, auto-deposited on disc and measured. The activity of 210Pb was assessed after radioactive equilibrium was achieved. The activity levels of 210Po ranged between 7.8 ± 0.3 and 17 ± 0.5 mBq per cigarette with an average of 12.9 ± 0.4 mBq per cigarette. Effective doses per year due to cigarette smoking were calculated assuming that 22% of the 210Pb and 210Po in tobacco were retained in the lungs of the smokers. It is concluded that for a smoker in Tunisia, the average effective dose is about 90.6 ± 3.3 µSv per year for a cigarette consumption of one pack of cigarettes per day. This value is somewhat lower than 106.4 ± 5.3 µSv per year estimated as the mean global effective dose from smoking.

Diffusion of radon through varying depths of cement.

Portland cement was mixed with different concentrations of radium chloride (1200, 2400 and 3600 Bq) to produce radioactive sources. These sources were surrounded with cement of different thickness (1, 2 and 4cm). The release of radon from these sources (before and after being surrounded) was studied. The results showed that radon release from the sources itself was less then its release from the same source after being surrounded by cement, and the release did not change with the thickness of cement. Samples were covered with a thin layer of polyethylene before being surrounded with cement. It was found that this additional layer reduced the radon exhalation. This thin layer stopped any reaction between the source and the surrounding cement during solidification of the cement layers. These reactions are thought to be the reason for the increase of radon exhalation from the sources surrounded by cement.

Absence of myocardial release of troponin T after coronary bypass surgery on a beating heart.

BACKGROUND: Coronary artery bypass grafting (CABG) operations in connection with cardiopulmonary bypass (CPB) appear to be associated with a number of side effects including trauma, cognitive dysfunction and myocardial damage. Accordingly, a current interest in performing CABG on a beating heart begins to emerge. This study examines the premise that conducting CABG on a beating heart limits the extent of myocardial injury and other complications. METHODS: Forty-five consecutive patients underwent CABG on a beating heart (group A, 12 patients) or in connection with CPB (group B, 33 patients). Inclusion criteria were poor left ventricular function and evolving myocardial ischemia or infarction. Results were assessed primarily on the basis of clinical outcome. In addition, measurement of plasma levels of troponin T (TnT), creatine kinase MB (CK-MB) and lactate dehydrogenase (LD) was conducted in 12 patients of group A preoperatively and 24 h after completion of surgery. These biological data were compared with those from control patients who underwent CABG in connection with CPB within the same time span. RESULTS: All patients in groups A and B survived the CABG procedure and those on a beating heart maintained an excellent perioperative hemodynamic measurements. The mean bypass time was 75 +/- 21 min and the mean cardiac standstill was 40 +/- 17 min. The intensive care unit stay was for group A: 18 +/- 4 h, group B: 48 +/- 12 h; and the total hospital stay was for group A: 6 +/- 1 days, group B: 8 +/- 3 days. Angiographic studies showed good anastomatic patency in both groups. Postoperative low output syndrome as indicated by the need of ionotropic drugs for more than 24 h was demonstrated in 4% and 6% of groups A and B, respectively. Limitation of myocardial injury in group A was demonstrated by the minimal increase in postoperative TnT levels (16.0 +/- 0.9 versus 30 +/- 8.0 pg/ml). A similar pattern of changes was observed with other infarction markers including CK-MB and LD. Contrastingly, the pre- and post-operative values of TnT in group B were 18 +/- 1.6 and 790 +/- 140 pg/ml, respectively. CONCLUSIONS: CABG on a beating heart shares many of the positive features of CPB with a distinct advantage of eliminating the intraoperative myocardial ischemia.