Dodecyl sorbitan ethers as antimicrobials against Gram-positive bacteria.

A range of amphiphilic sorbitan ethers has been synthesized in two steps from sorbitan following an acetalization/hydrogenolysis sequence. These sorbitan ethers and the acetal intermediates have been evaluated as antimicrobials against Gram-negative and Gram-positive bacteria. No antimicrobial activity was observed for Gram-negative bacteria. However, the compounds bearing a linear dodecyl chain exhibit antimicrobial activity (MIC as low as 8µg/mL) against Gram-positive bacteria such as Listeria monocytogenes, Enterococcus faecalis and Staphylococcus aureus. Encouraged by these preliminary results, dodecyl sorbitan was tested against a range of resistant strains and was found to be active against vancomycin-, methicillin- and daptomycin-resistant strains (MIC=32-64µg/mL).

Efficacy and safety of everolimus plus exemestane in patients with HR+, HER2- advanced breast cancer progressing on/after prior endocrine therapy in routine clinical practice: Primary results from the non-interventional study, STEPAUT.

BACKGROUND: STEPAUT, an Austrian non-interventional study, evaluated the safety and efficacy of everolimus plus exemestane in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) recurring/progressing on/after nonsteroidal aromatase inhibitors (NSAIs) in routine clinical practice. METHODS: Postmenopausal women with HR+, HER2- ABC progressing on/after NSAIs receiving everolimus plus exemestane in accordance with routine practice and the current version of Summary of Product Characteristics were eligible. Planned individual observation period corresponded to the duration of treatment until formal study end. RESULTS: Overall, 236 patients (median age: 65 years) were enrolled at 17 sites across Austria. The median progression-free survival (mPFS) in the overall population was 9.5 months (95% confidence interval [CI]: 8.6-10.7 months). The mPFS (95% CI) in patients who received everolimus 10 and 5 mg was 9.9 months (7.3-11.5 months) and 8 months (4.7-10.7 months), respectively. The median time to progression was numerically longer in patients who had a therapy break (11.9 months, 95% CI: 10.0-14.6 months) versus those who did not have any therapy break (10.7 months, 95% CI: 8.9-12.6 months). Patients experienced grade 1 (53.7%), grade 2 (35.9%), grade 3 (9.9%), grade 4 (0.2%) adverse events (AEs). The most common AEs of any grade were stomatitis, mucositis (53.8%), rash, exanthema (29.7%), loss of appetite, nausea (28.4%). CONCLUSIONS: Real-world safety and efficacy data from STEPAUT were consistent with results from BOLERO-2, supporting everolimus plus exemestane as a suitable treatment option for HR+, HER2- ABC recurring/progressing on/after NSAIs.

Genome, secretome and glucose transport highlight unique features of the protein production host Pichia pastoris.

BACKGROUND: Pichia pastoris is widely used as a production platform for heterologous proteins and model organism for organelle proliferation. Without a published genome sequence available, strain and process development relied mainly on analogies to other, well studied yeasts like Saccharomyces cerevisiae. RESULTS: To investigate specific features of growth and protein secretion, we have sequenced the 9.4 Mb genome of the type strain DSMZ 70382 and analyzed the secretome and the sugar transporters. The computationally predicted secretome consists of 88 ORFs. When grown on glucose, only 20 proteins were actually secreted at detectable levels. These data highlight one major feature of P. pastoris, namely the low contamination of heterologous proteins with host cell protein, when applying glucose based expression systems. Putative sugar transporters were identified and compared to those of related yeast species. The genome comprises 2 homologs to S. cerevisiae low affinity transporters and 2 to high affinity transporters of other Crabtree negative yeasts. Contrary to other yeasts, P. pastoris possesses 4 H+/glycerol transporters. CONCLUSION: This work highlights significant advantages of using the P. pastoris system with glucose based expression and fermentation strategies. As only few proteins and no proteases are actually secreted on glucose, it becomes evident that cell lysis is the relevant cause of proteolytic degradation of secreted proteins. The endowment with hexose transporters, dominantly of the high affinity type, limits glucose uptake rates and thus overflow metabolism as observed in S. cerevisiae. The presence of 4 genes for glycerol transporters explains the high specific growth rates on this substrate and underlines the suitability of a glycerol/glucose based fermentation strategy. Furthermore, we present an open access web based genome browser http://www.pichiagenome.org.

Open access to sequence: browsing the Pichia pastoris genome.

The first genome sequences of the important yeast protein production host Pichia pastoris have been released into the public domain this spring. In order to provide the scientific community easy and versatile access to the sequence, two web-sites have been installed as a resource for genomic sequence, gene and protein information for P. pastoris: A GBrowse based genome browser was set up at http://www.pichiagenome.org and a genome portal with gene annotation and browsing functionality at http://bioinformatics.psb.ugent.be/webtools/bogas. Both websites are offering information on gene annotation and function, regulation and structure. In addition, a WiKi based platform allows all users to create additional information on genes, proteins, physiology and other items of P. pastoris research, so that the Pichia community can benefit from exchange of knowledge, data and materials.

Synthesis, surfactant properties and antimicrobial activities of methyl glycopyranoside ethers.

A series of amphiphilic methyl glucopyranoside ethers incorporating various alkyl chain lengths has been synthesized from commercially available methyl glucopyranosides following an acetalisation/hydrogenolysis sequence. The amphiphilic properties of ethers and acetal intermediates were evaluated. Both families exhibit excellent surfactant properties with a maximum efficiency obtained for compounds bearing a linear dodecyl chain (CMC = 0.012 mM, γsat. = 30 mN m-1). Antimicrobial activity studies revealed an efficient activity (0.03 < MIC < 0.12 mM) against Gram-positive bacteria such as Listeria monocytogenes, Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus. More importantly, these compounds were found to be active against multi-resistant strains such as vancomycin-, methicillin- and daptomycin-resistant strains. Finally, it was found that antimicrobial activities are closely related to physicochemical properties and are also influenced by the nature of the carbohydrate moiety.

Impact of protein size distribution on gluten thermal reactivity and functional properties.

Wheat gluten structure was modified in different ways: Disulfide bonds were reduced by sulfitolysis, or protein chains were enzymatically hydrolyzed at three different degrees of proteolysis. A kinetic study of the thermal reactivity of the modified glutens showed that gluten aggregation kinetic was slowed in consequence to the shift of gluten size distribution toward smaller proteins. In contrary to sulfitolysis, proteolysis also affected the gluten reactivity potential because of the formation of numerous nonreactive species. Moreover, the thermally induced browning reaction was greatly enhanced by proteolysis, which increased the amount of free amine residues, substrates of the Maillard reaction. On the contrary, a whitening effect was observed for reduced gluten with bisulfite. Proteolysis was also found to decrease plasticized gluten viscosity, to increase gluten-based materials water solubility, and to enhance gluten adhesiveness properties but to reduce its mechanical performance. Sulfitolysis was considered as a possible way of extending gluten processability by extrusion or injection molding, whereas proteolysis was found to confer enhanced gluten stickiness that suggests new potential end uses of gluten in the pressure sensitive adhesives domain.

Mechanism of heat and shear mediated aggregation of wheat gluten protein upon mixing.

Changes in wheat gluten network structure upon mixing were studied from the biochemical analyses of gluten/glycerol blends mixed at 100 rpm with increasing times (up to 30 min) and temperatures of regulation (40, 60, and 80 degrees C). Whereas mixing induced protein solubility loss, the reduction of disulfide bonds restored protein extractability. But disulfide bond reduction became less efficient in promoting gluten extractability as mixing severity increased. This feature is consistent with the formation of a three-dimensional protein network stabilized by the formation of an increasing number of interchain disulfide bonds. Mixing induced a transient increase in free thiol groups while total thiol-equivalent groups dropped continuously. The changes were attributed to a shear-mediated scission of gluten disulfide bonds followed by oxidation of the thiyl radical moieties. Upon mixing, gluten solubility loss showed an Arrhenius-type temperature dependence with activation energy of 33.7 kJ.mol-1 instead of the more than 100 kJ.mol-1 reported for heat-induced gluten protein solubility loss. To explain this discrepancy, we postulated that during mixing, the disulfide interchange reactions are mediated by thiyl radicals in place of free thiol groups. A general model accounting for shear and temperature effects on gluten network structure is proposed.