Chemometric analysis of gas chromatography with flame ionisation detection chromatograms: a novel method for classification of petroleum products.

Most oil characterisation procedures are time consuming, labour intensive and utilise only part of the acquired chemical information. Oil spill fingerprinting with multivariate data processing represents a fast and objective evaluation procedure, where the entire chromatographic profile is used. Methods for oil classification should be robust towards changes imposed on the spill fingerprint by short-term weathering, i.e. dissolution and evaporation processes in the hours following a spill. We propose a methodology for the classification of petroleum products. The method consists of: chemical analysis; data clean-up by baseline removal, retention time alignment and normalisation; recognition of oil type by classification followed by initial source characterisation. A classification model based on principal components and quadratic discrimination robust towards the effect of short-term weathering was established. The method was tested successfully on real spill and source samples.

Fibrinolysis in pediatric patients undergoing cardiopulmonary bypass.

OBJECTIVE: Thromboelastographic evaluation of the influence of fibrinolysis on blood loss and blood product transfusions in children during cardiac surgery. DESIGN: Prospective study. SETTING: University-affiliated, pediatric medical center. PARTICIPANTS: Two hundred seventy-eight consecutive children undergoing cardiac surgery. INTERVENTIONS: Blood sampling for coagulation tests, including native and protamine-modified thromboelastography. MEASUREMENTS AND MAIN RESULTS: Blood coagulation tests were measured before, during, and after cardiopulmonary bypass (CPB). Demographic data, perioperative blood loss, and blood product transfusions were prospectively recorded. Fibrinolysis was defined as thromboelastography of A30/MA less than 0.85 (MA, maximum amplitude; A30, amplitude 30 minutes after MA) and was noted in 3% of children pre-CPB, 16% during CPB, and 3% post-CPB. Fibrinolysis before CPB was associated with poor cardiac output. Fibrinolysis during CPB occurred in young children (aged 350 +/- 836 days) undergoing complex surgery with prolonged CPB (119 +/- 48.8 minutes) and deep hypothermia (25.6 degrees C +/- 4.7 degrees C). These patients received blood products after CPB and were not fibrinolytic after transfusion. They incurred similar blood loss (in mL/kg) and received similar volumes of blood products (mL/kg) as age-matched and surgery-matched patients without fibrinolysis. CONCLUSION: A group of children at risk for fibrinolysis during CPB was identified. However, fibrinolysis during CPB did not influence blood loss or the total volume of blood products transfused.

Primary and secondary resistance of mycobacterium tuberculosis in Eastern Botswana.

Of 51 patients in Eastern Botswana who denied previous anti-tuberculosis treatment, 6 (11.8 %) were excreting tubercle bacilli resistant to one of the first-line drugs in regular use: 4 patients (7.8 %) showed resistance to isoniazid, 2 (3.9 %) to thiacetazone and none to streptomycin. Of 44 patients known to have been on previous anti-tuberculosis treatment, 31 (70.5 %) were found to show resistance to one or more of the first line drugs: 31 (70.5 %) to isoniazid, 12 (27.2 %) to streptomycin and 11 (25.9 %) to thiacetazone. No appreciable resistance was found to second line drugs. These resistance patterns, which correspond quite well with other published results from Africa, are related to the overall problem in Botswana, namely the failure of a high proportion of patients, to complete a full course of first line treatment.