Occupational infection due to Brucella abortus S19 among workers involved in vaccine production in Argentina.

The pathological consequences of exposure to the vaccine strain Brucella abortus S19 were evaluated in 30 employees from vaccine-manufacturing plants. Active brucellosis was diagnosed in 21 subjects, of whom only five recalled an accidental exposure. Clinical manifestations were mild, and only one patient presented a complication. After antimicrobial therapy, initially symptomatic patients either experienced clinical remission or had mild persistent symptoms. This is the first study reporting infection by B. abortus S19 among workers from vaccine-manufacturing plants, which in many cases was acquired from unnoticed exposures. Measures to improve the safety of B. abortus S19 handling should be implemented.

Synthesis of hydroxypropyl methacrylate/polysaccharide graft copolymers as matrices for controlled release tablets.

Hydrophilic matrices are an interesting option when developing drug delivery systems. With this aim, hydroxypropyl methacrylate was grafted onto hydroxypropyl starch and hydroxypropyl cellulose substrates by following the Ce(IV) redox initiation method. Different amounts of ethyleneglycol' dimethacrylate, 7 and 34 mol%, as the crosslinking monomer, were also added. The drying of grafted products was carried out by lyophilization, obtaining white powders. Reaction yields (percent grafting, grafting efficiency, etc.) and some physical characteristics of the powders (particle size, moisture uptake, density, morphology, etc.) were determined. These parameters indicate how useful these products may be as potential matrices for direct compressed tablets. In this light, the powder flowability and the binding properties of each copolymer were determined. The graft copolymers can be considered of great interest as direct compression excipients. Due to their different chemical structure and composition, they showed differences in viscoelastic properties that revealed an interesting range of possibilities for use in drug delivery formulations. Tablets formulated with conventional excipients were also tested. Dissolution tests of various tablets were carried out. In 12 hr, 60-80% of the model drugs was released.

Synthetic PMMA-grafted polysaccharides as hydrophilic matrix for controlled-release forms.

This paper describes the rheological behavior of starch and cellulose acrylic graft copolymers synthesized with the aim of obtaining controlled-release excipients. The rheological characteristics determine the final release properties of matrix tablets. The study of the storage and loss moduli (G' and G", respectively) and the viscosity allowed us to know if the polymer behavior was that of a gel and, hence, if it could act as a barrier to drug diffusion. Since dynamic measurements showed a storage modulus higher than the loss modulus, we assessed that all the polymers were gels. Thus, knowing that all the graft copolymers had acceptable properties for compression, the release of theophylline as a model drug at different pH was studied. Polymers with higher absorption capacity, viscosity, and compactibility allowed formulations with slower release rates.

Determination of the glass transition temperatures of some new methyl methacrylate copolymers using modulated temperature differential scanning calorimetry (MTDSC).

PURPOSE: The purpose of this study was to determine the glass transition temperatures of new graft copolymers using Modulated Temperature Differential Scanning Calorimetry (MTDSC), and to assess the differences between starch and cellulosic derivatives of methyl methacrylate and between two different drying methods used in their preparation. METHODS: Graft copolymers of methyl methacrylate were synthesized and dried by oven or freeze-drying. Surface area measurements and different thermal analysis techniques (Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and MTDSC) were used to characterize these copolymers. Results. DSC was not sensitive enough to identify the T(g)s of the copolymers, however they were clearly identifiable by MTDSC. T(g) values obtained may depend on the method of preparation that also altered their physical characteristics e.g. specific surface area. Cellulose derivatives showed lower T(g)s than starch derivatives. The results also depended on the drying method used, thus, freeze dried products had slightly lower T(g)s than oven dried products. CONCLUSIONS: MTDSC represents a useful thermal technique that allows the identification of glass transitions in these new copolymers with higher sensitivity and resolution than conventional DSC, separating the transition from overlapping phenomena such as decomposition or dehydration. The Tg of this new class of copolymers appeared to be dependent on polymer composition and drying method used.