Qualidade microbiologica da carne de frango irradiada em embalagem convencional e a vácuo / Microbiological evaluation of chicken breast meat irradiated in conventional and vacuum package

Foram avaliados os efeitos da radiação gama nas doses de 1,5 e 3,0kGy, em peitos de frango embalados em embalagem convencional e a vácuo. As amostras embaladas foram submetidas à irradiação e estocadas sob refrigeração (4ºC) por 30 dias. A radiação mostrou-se eficiente na redução de mesófilos aeróbios estritos e facultativos viáveis, coliformes totais e termotolerantes, com destaque para Salmonella spp. Os bolores e leveduras mostraram-se bastante resistentes à radiação. Os resultados sugerem que a dose de 3,0kGy pode ser utilizada no controle da microbiota do peito de frango armazenado sob refrigeração, sendo uma alternativa para o aumento da vida de prateleira por até 10 dias, ao garantir a segurança do consumidor pela eliminação de possíveis patógenos.

The effects of gamma radiation doses of 1.5 and 3.0kGy on chicken breasts packed under conventional or vacuum atmosphere were evaluated. The packed samples were subjected to irradiation and stored under refrigeration (4ºC) for 30 days. The radiation was efficient in reducing strict and facultative aerobic mesophiles, total and fecal coliforms, and mainly Salmonella spp. The molds and yeasts were very resistant to radiation. The results suggest that gamma radiation at 3.0kGy can be used to control the microbiota in chicken breast stored under refrigeration, as an alternative to extend the shelf-life for more than ten days and ensure the food safety by eliminating potential pathogens.

Thermodynamic evaluation and modeling of proton and water exchange associated with benzamidine and berenil binding to ß-trypsin

Serine-proteases are involved in vital processes in virtually all species. They are important targets for researchers studying the relationships between protein structure and activity, for the rational design of new pharmaceuticals. Trypsin was used as a model to assess a possible differential contribution of hydration water to the binding of two synthetic inhibitors. Thermodynamic parameters for the association of bovine ß-trypsin (homogeneous material, observed 23,294.4 ± 0.2 Da, theoretical 23,292.5 Da) with the inhibitors benzamidine and berenil at pH 8.0, 25°C and with 25 mM CaCl2, were determined using isothermal titration calorimetry and the osmotic stress method. The association constant for berenil was about 12 times higher compared to the one for benzamidine (binding constants are K = 596,599 ± 25,057 and 49,513 ± 2,732 M-1, respectively; the number of binding sites is the same for both ligands, N = 0.99 ± 0.05). Apparently the driving force responsible for this large difference of affinity is not due to hydrophobic interactions because the variation in heat capacity (DCp), a characteristic signature of these interactions, was similar in both systems tested (-464.7 ± 23.9 and -477.1 ± 86.8 J K-1 mol-1 for berenil and benzamidine, respectively). The results also indicated that the enzyme has a net gain of about 21 water molecules regardless of the inhibitor tested. It was shown that the difference in affinity could be due to a larger number of interactions between berenil and the enzyme based on computational modeling. The data support the view that pharmaceuticals derived from benzamidine that enable hydrogen bond formation outside the catalytic binding pocket of ß-trypsin may result in more effective inhibitors.

Congelamento de sêmen e inseminação artificial em cães, revisão / Semen freezing and artificial insemination in dogs, review

Foram utilizados para esta revisão trabalhos que estudassem o congelamento do sêmen canino. Os resultados na maioria das pesquisas constataram que o sêmen canino é de baixa qualidade. Publicações relatam obtenção de melhores resultados utilizando o tris-frutose-ácido cítrico como diluidor, glicerol como crioprotetor, método de congelamento lento e descongelamento em água a 37º C.

The radioprotective effect of a new aminothiol (20-PRA)

We examined the radioprotective effect of aminothiol 2-N-propylamine-cyclo-hexanethiol (20-PRA) on a human leukemic cell line (K562) following various radiation doses (5, 7.5 and 20 Gy) using a source of (60)Co gamma-rays. At 5 Gy and 1 nM 20-PRA, a substantial protective effect (58 per cent) was seen 24 h after irradiation, followed by a decrease at 48 h (11 per cent). At the high radiation dose (20 Gy) a low protective effect was also seen (35 per cent). In addition, the antitumorigenic potential of 10 nM 20-PRA was shown by the inhibition of crown gall formation induced by Agrobacterium tumefaciens. The radioprotective potency of 20-PRA is 10(5)-10(6) times higher than that of the aminothiol WR-1065 N-(2-mercaptoethyl) - 1,3-diaminopropane) whose protective effect is in the 0.1 to 1.0 mM range.

Host range specificity of two groups of soil-isolated Bacillus phages.

Foram testadas 95 estirpes de Bacillus e 10 de Staphylococcus aureus quanto a sensibilidade face a 14 fagos recem isolados de B. subtilis e 16 de B. pumilus.Todas as estirpes de S. aureus e 65 de Bacillus mostraram-se resistentes a lise por quaisquer dos fagos de Bacillus.Entre as estirpes de referencia, apenas aquelas de B.subtilis e B. pumilus foram lisadas por fagos de ambos os hospedeiros. As estirpes sensiveis recentemente isoladas foram identificadas como B. subtilis e B. pumilus Todos os fagos de B. subtilis eram especies especificos; no entanto, a maioria dos fagos de B. pumilus lisava ambas as especies. Tais dados confirmam a proximidade taxonomica destas especies