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The aim of this work was to investigate the structural features of type I collagen isoforms and collagen-based films at atomic and molecular scales, in order to evaluate whether and to what extent different protocols of slurry synthesis may change the protein structure and the final properties of the developed scaffolds. Wide Angle X-ray Scattering data on raw materials demonstrated the preferential orientation of collagen molecules in equine tendon-derived collagens, while randomly oriented molecules were found in bovine skin collagens, together with a lower crystalline degree, analyzed by the assessment of FWHM (Full Width at Half Maximum), and a certain degree of salt contamination. WAXS and FT-IR (Fourier Transform Infrared) analyses on bovine collagen-based films, showed that mechanical homogenization of slurry in acidic solution was the treatment ensuring a high content of super-organization of collagen into triple helices and a high crystalline domain into the material. In vitro tests on rat Schwannoma cells showed that Schwann cell differentiation into myelinating cells was dependent on the specific collagen film being used, and was found to be stimulated in case of homogenization-treated samples. Finally DHT/EDC crosslinking treatment was shown to affect mechanical stiffness of films depending on collagen source and processing conditions.

Background: The existence of Poison Centers for management and prevention of intoxications has been endorsed by the international experience. In Chile, the Toxicological Information Center at the Pontifical Catholic University of Chile has been active since 1992, receiving about 130.000 calls until 2002. Aim: To analyze the statistical data gathered throughout the first ten years of our Research Center. To delineate the epidemiological pa-ttern of intoxications in Chile. Material and methods: Retrospective study in which records from calls for toxicological information received during the 1992-2002 period reviewed. Analyzed data were total calls per year, place of call, exposure circumstances, age, sex, route of exposure and involved agents. Results: 96,468 calls analyzed. The main exposure circumstance was «unintentional» (78.6%), followed by «intentional» (16.9%). Intoxications in children under 5 years old motivated 50% of calls. According to route of exposure, ingestions involved 75,992 calls (78.8%). Medications were the most common substances, accounting for 49.2% of calls, followed by cleaning products (12.1%), pesticides (11.3%), industrial and chemical products (10.5%) and cosmetics (2.7%). Medications acting on the CNS were the most recurrent, with 19,096 reports. Conclusions: The epidemiological pattern for intoxications in Chile is very si-milar to that reported in developed and other Latin American countries. Children under 5 years old, are a high risk group for intoxications. It is imperative to improve the recording and follow-up of patients that call to the Center, to improve epidemiological data of intoxications in Chile (Rev Méd Chile 2004; 132: 493-9)

A study was undertaken to interpret the nature and function of the "plug like formation" observed inside the spermathecae of many phlebotomine sandflies dissected during field surveys. Trials were carried out on two laboratory reared species, Phlebotomus perniciosus and P. papatasi. The results showed that the "plug like formation" is a true mating plug (MP) containing immotile sperms. Our studies showed also that the MP evolves differently according to the physiological state of the mated female. In blood-fed females, it persists 22-25 hrs post mating. Follows a period of 3-4 days in which the spermathecae acquire different form from that of the virgin spermathecae, but sperms are still undistinguishable. Active sperms appear only a few hours before oviposition. After oviposition, however, spermathecae are void as in the virgin female. Thus, during the complete gonotrophic cycle the spermathecae display five different forms: a) normal and void; b) showing MP; c) distended and yellowish, MP absent; d) active sperms present; e) normal and void. In unfed females, MP was observed to last for 6 days post copula. The results show also that MP is interfering with reinsemination.