Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet

<p>Abstract</p> <p>Background</p> <p>N,N-Diethyl-3-methylbenzamide (deet) remains the gold standard for insect repellents. About 200 million people use it every year and over 8 billion doses have been applied over the past 50 years. Despite the widespread and increased interest in the use of deet in public health programmes, controversies remain concerning both the identification of its target sites at the olfactory system and its mechanism of toxicity in insects, mammals and humans. Here, we investigated the molecular target site for deet and the consequences of its interactions with carbamate insecticides on the cholinergic system.</p> <p>Results</p> <p>By using toxicological, biochemical and electrophysiological techniques, we show that deet is not simply a behaviour-modifying chemical but that it also inhibits cholinesterase activity, in both insect and mammalian neuronal preparations. Deet is commonly used in combination with insecticides and we show that deet has the capacity to strengthen the toxicity of carbamates, a class of insecticides known to block acetylcholinesterase.</p> <p>Conclusion</p> <p>These findings question the safety of deet, particularly in combination with other chemicals, and they highlight the importance of a multidisciplinary approach to the development of safer insect repellents for use in public health.</p

Ancillary contributions of heterologous biotin protein ligase and carbonic anhydrase for CO2 incorporation into 3-hydroxypropionate by metabolically engineered Pyrococcus furiosus

Acetyl-Coenzyme A carboxylase (ACC), malonyl-CoA reductase (MCR), and malonic semialdehyde reductase (MRS) convert HCO3- and acetyl-CoA into 3-hydroxypropionate (3HP) in the 3-hydroxypropionate/4-hydroxybutyrate carbon fixation cycle resident in the extremely thermoacidophilic archaeon Metallosphaera sedula. These three enzymes, when introduced into the hyperthermophilic archaeon Pyrococcus furiosus, enable production of 3HP from maltose and CO2. Sub-optimal function of ACC was hypothesized to be limiting for production of 3HP, so accessory enzymes carbonic anhydrase (CA) and biotin protein ligase (BPL) from M. sedula were produced recombinantly in Escherichia coli to assess their function. P. furiosus lacks a native, functional CA, while the M. sedula CA (Msed_0390) has a specific activity comparable to other microbial versions of this enzyme. M. sedula BPL (Msed_2010) was shown to biotinylate the -subunit (biotin carboxyl carrier protein) of the ACC in vitro. Since the native BPLs in E. coli and P. furiosus may not adequately biotinylate the M. sedula ACC, the carboxylase was produced in P. furiosus by co-expression with the M. sedula BPL. The baseline production strain, containing only the ACC, MCR, and MSR, grown in a CO2-sparged bioreactor reached titers of approximately 40mg/L 3HP. Strains in which either the CA or BPL accessory enzyme from M. sedula was added to the pathway resulted in improved titers, 120 or 370mg/L, respectively. The addition of both M. sedula CA and BPL, however, yielded intermediate titers of 3HP (240mg/L), indicating that the effects of CA and BPL on the engineered 3HP pathway were not additive, possible reasons for which are discussed. While further efforts to improve 3HP production by regulating gene dosage, improving carbon flux and optimizing bioreactor operation are needed, these results illustrate the ancillary benefits of accessory enzymes for incorporating CO2 into 3HP production in metabolically engineered P. furiosus, and hint at the important role that CA and BPL likely play in the native 3HP/4HB pathway in M. sedula. Biotechnol. Bioeng. 2016;113: 2652-2660. (c) 2016 Wiley Periodicals, Inc.</p

Reconstrução do LCA com o uso dos tendões dos músculos flexores mediais do joelho e fixação femoral com o sistema de Rigidifix®: relato preliminar Anterior cruciate ligament reconstruction using double hamstrings tendon graft and the femoral fixation by Rigidifix®: preliminary Study

O autor descreve a técnica de reconstrução do LCA no tratamento das instabilidades anterior do joelho, utilizando os tendões dos músculos flexores mediais do joelho (semitendíneo e grácil), fixados no fêmur pelo sistema de Rigidfix®; e na tíbia, com parafuso de interferência absorvível, através de um estudo preliminar de 54 joelhos operados. Na avaliação final pela escala de Lysholm os pacientes evoluíram de 46 pontos no pré-operatório para 92 pontos no pós-operatório.<br>The author describes the reconstruction technique of the anterior cruciate ligament reconstruction using the hamstrings tendon (semitendinosus and gracilis) in the management of anterior instabilities of the knee joint. Rigidfix® system is used to fix the graft on the femur and an absorbable interference screw was used for tibial fixation in a preliminary study in 54 knees. The final evaluation based on Lysholm score showed an improvement from 46 (preoperative) to 92 (postoperative)