Chemical investigations of bitumen from Neolithic archaeological excavations in Italy by GC/MS combined with principal component analysis

An analytical protocol involving microwave assisted solvent extraction and fractionation on silica gel columns followed by gas chromatography/mass spectrometry (GC/MS) and principal component analysis (PCA) of the chromatographic data was used for the characterization of bituminous residues sampled from Neolithic flint flakes and potsherds recovered from archaeological excavations in Abruzzo and Apulia (Italy). The analytical protocol was optimized and primarily tested in the study of geological bitumen (used as reference materials) from rocks and sediments of central-southern Italy (Abruzzo, Sicily and Lazio), and subsequently used to characterize the archaeological bitumen. Since bitumen is usually present in very low amounts in archaeological objects, we paid attention to improve the extraction efficiency of terpanes and steranes, the main soluble components of bitumen. The highest efficiency was obtained using microwave assisted extraction with a mixture of n-hexane/dichloromethane/methanol (80:15:5, v/v/v). Given that the composition of the bitumen varies depending on the area of origin, the results obtained from the archaeological materials allowed us not only to draw hypotheses on the possible function of tools/objects from which the bitumen is sampled, but also to obtain information on its geographical origin. In particular, PCA, used as a tool for an extensive analysis of chromatographic data, enabled us to correlate the quantitative chemical composition and the geographical origin of the samples, and finally to distinguish bitumen originating from the different Italian sites, based on their molecular profiles

Effects of cicletanine in the left circumflex coronary artery occlusion-reperfusion canine model of sudden death: analysis of 107 experiments using Cox's proportional hazards model.

Multivariate analysis of survival using Cox's proportional hazards model demonstrates that several clinically measurable covariates are determinants of life-threatening arrhythmias following left circumflex coronary artery occlusion-reperfusion in 107 dogs. These are heart rate, ST segment elevation and mean aortic pressure immediately (3 min) following occlusion, and the presence of early (0-10 min) post-occlusion sustained ventricular tachycardia. The risk of occlusion-reperfusion ventricular fibrillation was determined according to Cox's solution based on ST segment elevation, thus enabling quantification of the role of cicletanine. Since cicletanine-treated dogs had reduced mean ST segment elevation at 3 min post-occlusion, lower incidence of early post-occlusion (0-10 min) sustained ventricular tachycardia, and increased endogenous production of prostacyclin, and the latter was inversely correlated with the level of ST segment elevation, it is concluded that such favourable effects on the ischaemic myocardium were contributory to the improved outcome in these experiments. These effects on the ischaemic myocardium obtained in spite of a hypotensive action in the experimental setting might be regarded as desirable and it is therefore suggested that they should be further investigated by pharmacodynamic studies in human subjects