ABSTRACT:We report here on a new potentiometric biosensing principle for the detection of antibody−antigen interactions at the sensing membrane surface without the need to add a label or a reporter ion to the sample solution. This is accomplished by establishing a steady-state outward flux of a marker ion from the membrane into the contacting solution. The immunobinding event at the sensing surface retards the marker ion, which results in its accumulation at the membrane surface and hence in a potential response. The ion-selective membranes were surface-modified with an antibody against respiratory syncytial virus using click chemistry between biotin molecules functionalized with a triple bond and an azide group on the modified poly (vinyl chloride) group of the membrane. The bioassay sensor was then built up with streptavidin and subsequent biotinylated antibody. A quaternary ammonium ion served as the marker ion. The observed potential was found to be modulated by the presence of respiratory syncytial virus bound on the membrane surface. The sensing architecture was confirmed with quartz crystal microbalance studies, and stir effects confirmed the kinetic nature of the marker release from the membrane. The sensitivity of the model sensor was compared to that of a commercially available point-of-care test, with promising results.O

No abstract

In stressful situations, many animals release alarm pheromones to warn conspecifics of impending danger. The authors sought to establish experimental conditions for a larger study aimed at identifying alarm pheromones emitted by the rat. They placed rats in a specially designed chamber and exposed them to aversive tactile, visual and acoustic stimuli over the course of a few days. The researchers observed rats' behavior and analyzed air samples taken from their immediate environment under the following conditions: (i) when rats were unstressed; (ii) immediately after rats were exposed to aversive stimuli; and (iii) when rats were left alone in the chamber after being conditioned to fear imminent aversive stimuli. Stressed rats emitted several substances that are known to function as alarm pheromones in insects. When previously unstressed control rats were exposed to these same substances, they had a distinct behavioral fear response.

No abstract

The results of determination of toluene in samples of sewage sludge by purge and trap technique are presented. The research on the fermentation process allowed the observation of the phenomenon of toluene formation. The increase in concentration of this compound ranged from about 3 mg/L to more than 24 mg/L for samples taken from WWTP 'Gdansk Wschod' and from 0.6 mg/L to above 4.5 mg/ L for samples taken from WWTP 'Debogorze'. An increase in toluene concentration to a certain maximum value was observed during the first stage of this process; it was then followed by a concentration decrease.

The success of the testing of volatile organic compounds emitted by animals is dependent on the creation of appropriate conditions for air sampling subsequently used to assay and identify the compounds. These conditions play a particularly important role in the investigation of pheromones, which are secreted in extremely low concentrations. The authors have not come across any previous work which offers constructional solutions, which would allow avoidance of contamination of the air samples containing volatile substances secreted by animals.A constructional solution was developed, which provides optimal conditions for their sampling and isolation. Its main advantages are as follows: the exposure chamber (the chamber in which the animal is studied) is filled with synthetic air; the exposure chamber is separated from the atmospheric air with a synthetic air "jacket"; the exposure chamber has been constructed using materials which do not release chemicals and absorb them in trace quantities.

This study evaluated in vitro and in vivo drug release of bedaquiline from in situ forming gels (ISGs) containing 200 mg eq./g bedaquiline fumarate salt prepared with four different grades of poly(d,l-lactide) (PDLLA) or poly(d,l-lactide-co-glycolide) (PLGA) with a lactide/glycolide ratio of 50/50 or 75/25 and acid (A) or ester (E) end-capping in N-methyl-2-pyrrolidone at a polymer/solvent ratio of 20/80% (w/w). Mean in vitro drug release in 0.05 M phosphate buffer pH 7.4 with 1% (w/v) sodium lauryl sulphate was 37.3, 47.1, 53.3, and 62.3% within 28 days for ISGs containing PLGA5050A, PDLLA, PLGA7525A, and PLGA7525E, respectively. The data suggested that drug release was primarily controlled by precipitated drug redissolving, rather than polymer erosion. In vivo pharmacokinetic profiles after subcutaneous injections in rats were comparable for all ISGs (mean half-lives (t1/2) ranged from 1411 to 1695 h) and indicated a sustained drug release when compared to a solution of bedaquiline fumarate salt in polyethylene glycol 400/water 50/50% (v/v) (mean t1/2 of 895 h). In conclusion, PLGA or PDLLA-based ISGs have shown potential for parenteral sustained delivery of bedaquiline, suggesting further preclinical and clinical studies. From a formulation point of view, this case example highlights the importance of the interplay between drug solubility in biological media and dissolution of drug precipitates, which, in addition to the incorporation of diffusion controlling polymers, governs the release of the active drug.