Polymer-Degrading Enzymes of Pseudomonas chloroaphis PA23 Display Broad Substrate Preferences.

Although many bacterial lipases and PHA depolymerases have been identified, cloned, and characterized, there is very little information on the potential application of lipases and PHA depolymerases, especially intracellular enzymes, for the degradation of polyester polymers/plastics. We identified genes encoding an intracellular lipase (LIP3), an extracellular lipase (LIP4), and an intracellular PHA depolymerase (PhaZ) in the genome of the bacterium Pseudomonas chlororaphis PA23. We cloned these genes into Escherichia coli and then expressed, purified, and characterized the biochemistry and substrate preferences of the enzymes they encode. Our data suggest that the LIP3, LIP4, and PhaZ enzymes differ significantly in their biochemical and biophysical properties, structural-folding characteristics, and the absence or presence of a lid domain. Despite their different properties, the enzymes exhibited broad substrate specificity and were able to hydrolyze both short- and medium-chain length polyhydroxyalkanoates (PHAs), para-nitrophenyl (pNP) alkanoates, and polylactic acid (PLA). Gel Permeation Chromatography (GPC) analyses of the polymers treated with LIP3, LIP4, and PhaZ revealed significant degradation of both the biodegradable as well as the synthetic polymers poly(ε-caprolactone) (PCL) and polyethylene succinate (PES).

Profiles of polypharmacy in older adults and medication associations with signs of aspiration.

BACKGROUND: Polypharmacy and specific medication classes are prevalent in older adults. Their relationships with swallowing disorders are not well explored, which would best be managed holistically, with consideration of medication profiles. This study aimed to establish profiles of polypharmacy in older adults and investigate the associations of polypharmacy and medication class with signs of aspiration during swallowing. METHODS: This was a secondary retrospective analysis of data from 291 adults aged 60 years and older. Polypharmacy was profiled numerically and described. Multivariate logistic regression was used to identify associations between medication classes with signs of aspiration, while controlling for independent variables of demographics, functional status, and medical history. RESULTS: Three distinct profiles of polypharmacy were described. Higher numbers of medications were associated with higher age, lower functional status, nursing home residency, multimorbidity, and showing signs of aspiration. Thirty-four classes of medications were found in this study, benzodiazepines were the only class independently associated with signs of aspiration. CONCLUSIONS: Different profiles of polypharmacy can be observed in older adults, but none were independently associated with signs of aspiration. In addition to known demographic and functional status variables, benzodiazepine-use was found to be independently associated with signs of aspiration (p = .005, B = 7.94).