Combining branched copolymers with additives generates stable thermoresponsive emulsions with in situ gelation upon exposure to body temperature

Branched copolymer surfactants (BCS) containing thermoresponsive polymer components, hydrophilic components, and hydrophobic termini allow the formation of emulsions which switch from liquid at room temperature to a gel state upon heating. These materials have great potential as in situ gel-forming dosage forms for administration to external and internal body sites, where the emulsion system also allows effective solubilisation of a range of drugs with different chemistries. These systems have been reported previously, however there are many challenges to translation into pharmaceutical excipients. To transition towards this application, this manuscript describes the evaluation of a range of pharmaceutically-relevant oils in the BCS system as well as evaluation of surfactants and polymeric/oligomeric additives to enhance stability. Key endpoints for this study are macroscopic stability of the emulsions and rheological response to temperature. The effect of an optimal additive (methylcellulose) on the nanoscale processes occurring in the BCS-stabilised emulsions is probed by small-angle neutron scattering (SANS) to better comprehend the system. Overall, the study reports an optimal BCS/methylcellulose system exhibiting sol-gel transition at a physiologically-relevant temperature without macroscopic evidence of instability as an in situ gelling dosage form.

Polymer architecture dictates thermoreversible gelation in engineered emulsions stabilised with branched copolymer surfactants

Polymer architecture allows control of thermoreversible gelation in branched copolymer-stabilised emulsions.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for the rapid identification of yeasts causing bloodstream infections

Few studies have systematically standardised and evaluated matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of yeasts from bloodstream infections. This is rapidly becoming pertinent for early identification of yeasts and appropriate antifungal therapy. We used 354 yeast strains identified by polymerase chain reaction (PCR) sequencing for standardisation and 367 blind clinical strains for validation of our MALDI-TOF MS protocols. We also evaluated different sample preparation methods and found the on-plate formic acid extraction method as most cost- and time-efficient. The MALDI-TOF assay correctly identified 98.9% of PCR-sequenced yeasts. Novel main spectrum projections (MSP) were developed for Candida auris, C. viswanathii and Kodamaea ohmeri, which were missing from the Bruker MALDI-TOF MS database. Spectral cut-offs computed by receiver operating characteristics (ROC) analysis showed 99.4% to 100% accuracy at a log score of ≥ 1.70 for C. tropicalis, C. parapsilosis, C. pelliculosa, C. orthopsilosis, C. albicans, C. rugosa, C. guilliermondii, C. lipolytica, C. metapsilosis, C. nivariensis. The differences in the species-specific scores of our standardisation and blind validation strains were not statistically significant, implying the optimal performance of our test protocol. The MSPs of the three new species also were validated. We conclude that MALDI-TOF MS is a rapid, accurate and reliable tool for identification of bloodstream yeasts. With proper standardisation, validation and regular database expansion, its efficiency can be further enhanced.

Study on Heavy Metal Resistant Bacteria in Guheswori Sewage Treatment Plant

Removal of heavy metals from wastewater needs advance chemical technology and is more expensive too. The cheaper alternative for this is the bioremediation using heavy metals resistant microorganisms. In this study, 10 heavy metal resistant bacteria were isolated from oxidation ditch of wastewater treatment plant of Bagmati Area Sewerage Project. These include chromium resistant Staphylococcus spp, Escherichia coli, Klebsiella spp; cadmium resistant Acinetobacter spp, Flavobacterium spp, Citrobacter spp; nickel resistant Staphylococcus spp, Bacillus spp; copper resistant Pseudomonas spp; and cobalt resistant Methylobacterium spp. All the isolates showed high resistance to heavy metals with Minimum Inhibitor Concentration (MIC) for heavy metals ranging from 150 mug/ml to 500 mug/ml. Six resistant isolates showed multiple tolerance to heavy metals. All the 10 isolates also showed antibiotic resistance of which 10% were resistant to single antibiotic and 90% were multi-antibiotic resistant. Heavy metal tolerance test showed maximum microbial tolerance to chromium and minimum tolerance to nickel in mixed liquor sample of oxidation ditch.Keywords: Heavy metal resistant bacteria, multiple tolerance, antibiotic resistance, Guheswori Sewage Treatment Plantdoi: 10.3126/on.v6i1.1655Our Nature (2008)6:52-57