Nile red fluorescence screening facilitating neutral lipid phenotype determination in budding yeast, Saccharomyces cerevisiae, and the fission yeast Schizosaccharomyces pombe.

Investigation of yeast neutral lipid accumulation is important for biotechnology and also for modelling aberrant lipid metabolism in human disease. The Nile red (NR) method has been extensively utilised to determine lipid phenotypes of yeast cells via microscopic means. NR assays have been used to differentiate lipid accumulation and relative amounts of lipid in oleaginous species but have not been thoroughly validated for phenotype determination arising from genetic modification. A modified NR assay, first described by Sitepu et al. (J Microbiol Methods 91:321-328, 2012), was able to detect neutral lipid changes in Saccharomyces cerevisiae deletion mutants with sensitivity similar to more advanced methodology. We have also be able to, for the first time, successfully apply the NR assay to the well characterised fission yeast Schizosaccharomyces pombe, an increasingly important organism in biotechnology. The described NR fluorescence assay is suitable for increased throughput and rapid screening of genetically modified strains in both the biotechnology industry and for modelling ectopic lipid production for a variety of human diseases. This ultimately negates the need for labour intensive and time consuming lipid analyses of samples that may not yield a desirable lipid phenotype, whilst genetic modifications impacting significantly on the cellular lipid phenotype can be further promoted for more in depth analyses

High-Throughput Screening of Australian Marine Organism Extracts for Bioactive Molecules Affecting the Cellular Storage of Neutral Lipids

Mammalian cells store excess fatty acids as neutral lipids in specialised organelles called lipid droplets (LDs). Using a simple cell-based assay and open-source software we established a high throughput screen for LD formation in A431 cells in order to identify small bioactive molecules affecting lipid storage. Screening an n-butanol extract library from Australian marine organisms we identified 114 extracts that produced either an increase or a decrease in LD formation in fatty acid-treated A431 cells with varying degrees of cytotoxicity. We selected for further analysis a non-cytotoxic extract derived from the genus Spongia (Heterofibria). Solvent partitioning, HPLC fractionation and spectroscopic analysis (NMR, MS) identified a family of related molecules within this extract with unique structural features, a subset of which reduced LD formation. We selected one of these molecules, heterofibrin A1, for more detailed cellular analysis. Inhibition of LD biogenesis by heterofibrin A1 was observed in both A431 cells and AML12 hepatocytes. The activity of heterofibrin A1 was dose dependent with 20 µM inhibiting LD formation and triglyceride accumulation by ∼50% in the presence of 50 µM oleic acid. Using a fluorescent fatty acid analogue we found that heterofibrin A1 significantly reduces the intracellular accumulation of fatty acids and results in the formation of distinct fatty acid metabolites in both cultured cells and in embryos of the zebrafish Danio rerio. In summary we have shown using readily accessible software and a relatively simple assay system that we can identify and isolate bioactive molecules from marine extracts, which affect the formation of LDs and the metabolism of fatty acids both in vitro and in vivo

Bezlotoxumab for Prevention of Recurrent Clostridium difficile Infection

BACKGROUND Clostridium difficile is the most common cause of infectious diarrhea in hospitalized patients. Recurrences are common after antibiotic therapy. Actoxumab and bezlotoxumab are human monoclonal antibodies against C. difficile toxins A and B, respectively. METHODS We conducted two double-blind, randomized, placebo-controlled, phase 3 trials, MODIFY I and MODIFY II, involving 2655 adults receiving oral standard-of-care antibiotics for primary or recurrent C. difficile infection. Participants received an infusion of bezlotoxumab (10 mg per kilogram of body weight), actoxumab plus bezlotoxumab (10 mg per kilogram each), or placebo; actoxumab alone (10 mg per kilogram) was given in MODIFY I but discontinued after a planned interim analysis. The primary end point was recurrent infection (new episode after initial clinical cure) within 12 weeks after infusion in the modified intention-to-treat population. RESULTS In both trials, the rate of recurrent C. difficile infection was significantly lower with bezlotoxumab alone than with placebo (MODIFY I: 17% [67 of 386] vs. 28% [109 of 395]; adjusted difference, −10.1 percentage points; 95% confidence interval [CI], −15.9 to −4.3; P<0.001; MODIFY II: 16% [62 of 395] vs. 26% [97 of 378]; adjusted difference, −9.9 percentage points; 95% CI, −15.5 to −4.3; P<0.001) and was significantly lower with actoxumab plus bezlotoxumab than with placebo (MODIFY I: 16% [61 of 383] vs. 28% [109 of 395]; adjusted difference, −11.6 percentage points; 95% CI, −17.4 to −5.9; P<0.001; MODIFY II: 15% [58 of 390] vs. 26% [97 of 378]; adjusted difference, −10.7 percentage points; 95% CI, −16.4 to −5.1; P<0.001). In prespecified subgroup analyses (combined data set), rates of recurrent infection were lower in both groups that received bezlotoxumab than in the placebo group in subpopulations at high risk for recurrent infection or for an adverse outcome. The rates of initial clinical cure were 80% with bezlotoxumab alone, 73% with actoxumab plus bezlotoxumab, and 80% with placebo; the rates of sustained cure (initial clinical cure without recurrent infection in 12 weeks) were 64%, 58%, and 54%, respectively. The rates of adverse events were similar among these groups; the most common events were diarrhea and nausea. CONCLUSIONS Among participants receiving antibiotic treatment for primary or recurrent C. difficile infection, bezlotoxumab was associated with a substantially lower rate of recurrent infection than placebo and had a safety profile similar to that of placebo. The addition of actoxumab did not improve efficacy. (Funded by Merck; MODIFY I and MODIFY II ClinicalTrials.gov numbers, NCT01241552 and NCT01513239.

MAPK9: Ein neuer Regulator des Triglyzerid-Stoffwechsels, entdeckt durch siRNA Screening

Lipid homeostasis is an essential factor for proper function both at the level of a cell and of an organism. Dysregulation of this process is responsible for some of the major health concerns of our societies such as obesity and atherosclerosis. Considering the wide variety of lipids and the high dynamic of the system, it is clear that regulation is required to keep the appropriate balance between the different lipids. Although a few regulation pathways are already characterized, some others still wait to be discovered. In order to unravel new players involved in lipid regulation, a screening procedure was developed combining RNA interference in Hela cells and thin layer chromatography. Thereby, it is possible to monitor modifications of lipid composition resulting from siRNA knock-down. Furthermore, the potential of mass spectrometry as a lipid analysis tool in large-scale studies was evaluated. This method was then applied to an essential family of regulatory proteins, the kinases. Lipid composition of 600 kinases knock-downs was analyzed. Mostly, variations in triglyceride and cholesterol levels were observed, suggesting that these lipids are more subject to variation in the cells. Unfortunately, it appears that the screen suffered from a high-rate of off-targets effects, implying that most of the phenotypes observed can’t reliably be linked to the corresponding kinase knock-downs. However, several interesting conclusions can still be derived from this screen. First, it was observed that several siRNA induce a decrease in cholesterol, which is coupled to accumulation of a new lipid. Several lines of evidence suggest that this new lipid is in fact a methylated sterol precursor such as lanosterol or demethyllanosterol. Previously, HMG-CoA reductase was considered as the rate-limiting enzyme of cholesterol biosynthesis and the major regulated step of this process. These data show that another major regulation step occurs more downstream in the pathway at the level of methylated cholesterol precursors. Furthermore, MAPK9 was identified as a new regulator of triglyceride homeostasis at the cellular level. Upon MAPK9 knock-down, an increase in triglyceride content was observed both by thin layer chromatography and mass spectrometry. Accordingly, these cells present an increase in lipid droplets, the cellular organelles responsible for triglyceride storage. Sty1 was also identified as the functional homolog of MAPK9 in S. pombe for this process, as similar increase in triglyceride and lipid droplets is observed in a deletion strain for this gene. Although more detailed studies will be necessary to unravel the molecular mechanism of this process, these data suggest the evolutionary conserved implication of the MAP kinase pathway in the regulation of lipid storage both in humans and in yeasts

A prospective case series evaluating the safety and efficacy of the Klox BioPhotonic System in venous leg ulcers

Andreas Nikolis,1 Doria Grimard,2 Yves Pesant,3 Giovanni Scapagnini,4 Denis V&eacute;zina5 1Division of Plastic Surgery, Victoria Park Research Centre, Montreal, 2Q&amp;T Research Chicoutimi, Chicoutimi, 3St-Jerome Medical Research Inc., St-Jerome, Quebec, Canada; 4Department of Medicine and Health Sciences, School of Medicine, University of Molise, Campobasso, Italy; 5Klox Technologies, Laval, Quebec, Canada Purpose: To investigate the safety and efficacy of the BioPhotonic System developed by Klox Technologies in a case series of ten patients with venous leg ulcers.Patients and methods: Ten patients with chronic venous leg ulcers, having failed on at least one previous therapy, were enrolled into this case series.Results: Nine patients were evaluable for efficacy. A response (defined as decrease in wound surface area) was observed in seven patients (77.8%). Of these, four patients (44.4%) achieved wound closure on average 4 months (127.5 days) following the beginning of the treatment. Two patients did not respond to the investigational treatment. Quality of life improved over time throughout the study. Compliance was excellent, with 93.2% of visits completed as per protocol. Safety was unremarkable, with only four treatment-emergent-related adverse events, for which no specific intervention was required.Conclusion: The BioPhotonic System was shown to be safe and extremely well tolerated. It also demonstrated potential in terms of wound closure, wound surface area decrease, and wound bed preparation. Keywords: biophotonics, light, photobiomodulation, venous leg ulcer