Liberação de peróxido de hidrogênio por fagócitos de glândulas mamárias bovinas hígidas e infectadas

O objetivo do presente estudo foi avaliar a capacidade de liberação de peróxido de hidrogênio (H2O2) por fagócitos oriundos de glândulas mamárias bovinas sadias e infectadas. Desse modo, 73 amostras de leite provenientes das glândulas mamárias foram classificadas em sadias e infectadas de acordo com a cultura bacteriológica e a contagem de células somáticas (CCS). Após o isolamento das células do leite, procedeu-se à contagem diferencial de leucócitos e determinação da liberação de H2O2 pela oxidação da solução de vermelho fenol. Foi observada menor liberação de H2O2 pelos fagócitos oriundos dos quartos mamários infectados, assim como houve correlação negativa entre a liberação de H2O2 por fagócitos e a CCS (r=-0,34; P=0,0025), e a porcentagem de neutrófilos (r=-0,24; P=0,04). Além disso, houve tendência de menor liberação de H2O2 pelos fagócitos estimulados por forbol 12-miristato 13-acetato nas glândulas mamárias infectadas. Entretanto, observou-se maior liberação de H2O2 pelos fagócitos em 1mL de leite nos quartos mamários infectados, ao considerar a CCS mL-1. Pode-se concluir que fagócitos de quartos mamários infectados apresentaram menor liberação de H2O2, o que indica menor capacidade microbicida. Por outro lado, observou-se maior liberação de H2O2 pelos fagócitos em 1mL de leite nos quartos infectados, fato que pode contribuir com o maior recrutamento de leucócitos para a glândula mamária e/ou a persistência do processo inflamatório.

Synthetic biology: a novel approach for the construction of industrial microorganisms

The recent achievement of synthesising a functioning bacterial chromosome marks a coming of age for engineering living organisms. In the future this should allow the construction of novel organisms to help solve the problems facing the human race, including health care, food, energy and environmental protection. In this minireview, the current state of the field is described and the role of synthetic biology in biotechnology in the short and medium term is discussed. It is particularly aimed at the needs of food technologists, nutritionists and other biotechnologists, who might not be aware of the potential significance of synthetic biology to the research and development in their fields. The potential of synthetic biology to produce interesting new polyketide compounds is discussed in detail.

Two-Phase Frictional Pressure Drop and Flow Boiling Heat Transfer for R245fa in a 2.32-mm Tube

Experimental two-phase frictional pressure drop and flow boiling heat transfer results are presented for a horizontal 2.32-mm ID stainless-steel tube using R245fa as working fluid. The frictional pressure drop data was obtained under adiabatic and diabatic conditions. Experiments were performed for mass velocities ranging from 100 to 700 kg m−2 s−1 , heat flux from 0 to 55 kW m−2 , exit saturation temperatures of 31 and 41◦C, and vapor qualities from 0.10 to 0.99. Pressures drop gradients and heat transfer coefficients ranging from 1 to 70 kPa m−1 and from 1 to 7 kW m−2 K−1 were measured. It was found that the heat transfer coefficient is a strong function of the heat flux, mass velocity, and vapor quality. Five frictional pressure drop predictive methods were compared against the experimental database. The Cioncolini et al. (2009) method was found to work the best. Six flow boiling heat transfer predictive methods were also compared against the present database. Liu and Winterton (1991), Zhang et al. (2004), and Saitoh et al. (2007) were ranked as the best methods. They predicted the experimental flow boiling heat transfer data with an average error around 19%.