An ESR assay for alpha-amylase activity toward succinylated starch, amylose and amylopectin.

The esterification of the three polysaccharides, starch, amylose and amylopectin was carried out in pyridine-DMSO by succinic anhydride. The carboxylic groups in the succinylated polysaccharides were measured by FT-IR spectroscopy. The succinic derivatives were tested as alpha-amylase (1,4-alpha-D-glucan glucano hydrolase, E.C. 3.2.1.1) substrates. A colorimetric assay of the alpha-amylase activity indicated that this enzyme is active on succinic esters of starch and amylose and that the activity shows a linear decrease with the number of succinic units introduced into the polysaccharide. Since the colorimetric test was not suitable for the detection of the alpha-amylase activity when succinylated amylopectin was the substrate, we set-up an assay based on the labeling by a paramagnetic probe of the free carboxylic groups of succinylated polysaccharides. The kinetics of the alpha-amylase reaction were monitored by ESR spectroscopy through the increase of the mobility of the paramagnetic probe. The spin label used was the commercially available 4-amino-tempo. By this method we demonstrated that alpha-amylase is active on succinylated amylopectin. The utility of the assay for monitoring alpha-amylase activity when other methods (i.e. colorimetric tests) fail, is discussed.

[Mortality caused by pleural mesothelioma in the 1979-1983 lustre in Italy regarding provinces and single local health districts]. / Mortalità per mesotelioma pleurico nel quinquennio 1979-1983 in Italia con riferimento alle provincie e singole USSL.

The geographic distribution of deaths from pleural mesothelioma in Italian provinces was analysed over the five-year period 1979-1983. In the provinces where the mortality rates were markedly higher than the national average, a further analysis was made on the data referred to the local health districts (USSL) of each province. It was thus possible, in some cases, to identify small, high risk areas which corresponded, as expected, to the location of large factories or shipyards using asbestos.