Enzyme-encapsulating polymeric nanoparticles: A potential adjunctive therapy in Pseudomonas aeruginosa biofilm-associated infection treatment.

Pseudomonas aeruginosa is a pathogen known to be associated with a variety of diseases and conditions such as cystic fibrosis, chronic wound infections, and burn wound infections. A novel approach was developed to combat the problem of biofilm antibiotic tolerance by reverting biofilm bacteria back to the planktonic mode of growth. This reversion was achieved through the enzymatic depletion of available pyruvate using pyruvate dehydrogenase, which induced biofilm bacteria to disperse from the surface-associated mode of growth into the surrounding environment. However, direct use of the enzyme in clinical settings is not practical as the enzyme is susceptible to denaturation under various storage conditions. We hypothesize that by encapsulating pyruvate dehydrogenase into degradable, biocompatible poly(lactic-co-glycolic) acid nanoparticles, the activity of the enzyme can be extended to deplete available pyruvate and induce dispersion of mature Pseudomonas aeruginosa biofilms. Several particle formulations were attempted in order to permit the use of the smallest dose of nanoparticles while maintaining pyruvate dehydrogenase activity for an extended time length. The nanoparticles synthesized using the optimal formulation showed an average size of 266.7 ±â€¯1.8 nm. The encapsulation efficiency of pyruvate dehydrogenase was measured at 17.9 ±â€¯1.4%. Most importantly, the optimal formulation dispersed biofilms and exhibited enzymatic activity after being stored at 37 °C for 6 days.

Tandem capillary column gas chromatography-mass spectrometric determination of the organophosphonate nerve agent surrogate dimethyl methylphosphonate in gaseous phase.

A procedure based on capillary column gas chromatographic-mass spectrometric (GC-MS) confirmation was developed for the verification of the ubiquitous and versatile chemical and nerve agent simulant, dimethyl methyl phosphonate (DMMP; CAS# 756-79-6), from gaseous samples. This method was developed to verify low nanogram DMMP concentrations during testing of a nerve agent detection system. Standard solutions of 1, 5, 10, 50, 100, 500, and 1000ng/ml DMMP in acetonitrile were employed. Through 15 calibration curves using the 5 lowest concentrations, coefficient of determination (r(2)) values showed a mean of 0.998 (0.992-1.000). An additional 15 calibration curves likewise containing 5 concentrations of DMMP spanning 3 orders of magnitude (1, 50, 100, 500, and 1000ng/ml) yielded a mean r(2) of 0.997 (0.991-1.000). Sixty-five nitrogen diluted gaseous samples varying from 1.0 to 10.0microl in volume were analyzed and concentrations of DMMP ranging from 1 to 1000ng/ml were confirmed. An additional 35 vapor samples in UHP N(2) ranging in DMMP concentration from 5.8microg/m(3) to 1.0mg/m(3) were analyzed by increasing sample volume range to between 10.0 and 100microl. For gaseous samples with volumes>1.0microl, the lowest concentration observed was 5.8microg/m(3). The method detection limit (Appendix B of Title 40 CFR, United States) for 1.0microl autoinjected standards in acetonitrile was determined to be 0.331ng/ml. Method precision for 15 independently analyzed standards of 25ng/ml had a relative standard deviation of 1.168. This method demonstrated high linearity across a wide range of concentrations, as well as excellent sensitivity and repeatability, and proved applicable to other lower alkyl-phosphonates.

Multigenerational effects in deer mice (Peromyscus maniculatus) exposed to hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX).

Contamination by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been identified at areas of explosive manufacturing, processing, storage, and usage. Anaerobic conversion of RDX to N-nitroso metabolites (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX)) has been demonstrated in the environment and in gastrointestinal tracts of mammals in vivo. Thus, potential exists for exposure to these N-nitroso compounds. While exposed to TNX via drinking water ad libitum, deer mice (Peromyscus maniculatus) were bred in three generations to produce cohorts F1A-D, F2A-B, and F3A. TNX was administered at four exposure levels: control (0 microg L(-1)), 10 microg L(-1), 100 microg L(-1), and 1000 microg L(-1). Endpoints investigated include: offspring production, offspring survival, offspring weight gain, and offspring organ weights. TNX exposure decreased litter size and increased postpartum mortality of offspring at the highest exposure level.