Controlled release of biomolecules from temperature-sensitive hydrogels prepared by radiation polymerization.

Poly(acryloyl-L-proline methyl ester)-based hydrogels containing 1 and 5% of a crosslinking agent were studied as drug delivery systems. The drug loading properties were investigated by matrix incubation into solutions containing biomolecules with molecular weight ranging between 300 and 65,000 Da. The loading yield was found to depend on both the crosslinking degree and the molecular weight of the drug. In vitro release studies were carried out with both swollen and dry matrices loaded with gentamicin, isoniazid and insulin. Gentamicin and isoniazid were released by a bimodal Fickian diffusion with a remarkable burst that was found to depend on both matrix crosslinking degree and physical state. In vivo, the subcutaneous implantation into mice of the isoniazid loaded matrices allowed for an efficient drug release for 800 h. In vitro insulin was released from the swollen matrices for 1500 h by diffusional Fickian mechanism while the dry ones displayed a lag time followed by Fickian diffusion release. The subcutaneous implantation of the insulin-loaded matrices into diabetic mice induced a remarkable decrease in the glucose concentrations in blood. In particular, the dry 1% matrices were found to maintain a low glucose level for 700 h.

Skin contamination and low airborne nickel exposure of electroplaters.

The present study was performed to evaluate the role of hand and facial contamination in the absorption of soluble nickel compounds in 41 male subjects employed in electroplating operations in 25 small factories in the province of Florence (Italy). Personal exposure to airborne nickel ranged from 0.10 to 42 micrograms/m3; the median (range) urine, hands and face nickel levels were 4.2 (0.7-50) micrograms/l, 39 (1.9-547) micrograms, 9.0 (1.0-86) micrograms, respectively. Face nickel values explained the bulk of the variance in urine nickel levels (42%). In stepwise multiple regression analysis all other variables were not significant. The log-linear model can be expressed as: log (urine-Ni) = 0.295 + 0.593 log (face-Ni). Our results suggest that skin contamination, especially facial skin, plays an important role in nickel absorption in exposed workers.

[Determination of organic phosphate plasticizers and solvents in the environmental air of the shoe industry]. / Determinazione dei plastificanti fosforganici e dei solventi nell'aria ambientale dell'industria calzaturiera.

We have carried out a laboratory research with the purpose of evaluating the absorbing capacities of various commercial active coals, equipping therefore a room where we have maintained a constant concentration of solvents in the air. We have determined through a gaschromatographic method the conditions of dimension of the test tube, the quantity in weight of coal and the speed of the flow to secure at least 4 1 of sampling. Using test tubes of 10 mm of inner diameter, 70 mm long containing 0.8 g of active coal, 20-35 mesh, with diameter from 0.33 to 1 mm2, subjected to an aspiration of 0.35 l/m, we have diluted the solvents with CS2 and determined their quantity through gaschromatographic analysis. We have completed a research of trycresyl phosphate and other plasticizers upon 54 different types of cement used in 30 shoe factories in the comprehensory of Lastra a Signa. On the cement samples and glues it has been done the mineralization with sulphonitric mixture. It has been observed that the presence of the phosphorus in the samples of the cement is not always due to the presence of phosphorganic plasticizers. We have then carried out a distillation from the cements with n-hexane and a thin layer chromatographic analysis using as comparison commercial trycresyl phosphate. The various cements examined did not contain plasticizers.