Encapsulated droplet interface bilayers as a platform for high-throughput membrane studies.

Whilst it is highly desirable to produce artificial lipid bilayer arrays allowing for systematic high-content screening of membrane conditions, it remains a challenge due to the combined requirements of scaled membrane production, simple measurement access, and independent control over individual bilayer experimental conditions. Here, droplet bilayers encapsulated within a hydrogel shell are output individually into multi-well plates for simple, arrayed quantitative measurements. The afforded experimental throughput is used to conduct a 2D concentration screen characterising the synergistic pore-forming peptides Magainin2 and PGLa. Maximal enhanced activity is revealed at equimolar peptide concentrations via a membrane dye leakage assay, a finding consistent with models proposed from NMR data. The versatility of the platform is demonstrated by performing in situ electrophysiology, revealing low conductance pore activity (∼15 to 20 pA with 4.5 pA sub-states). In conclusion, this array platform addresses the aforementioned challenges and provides new and flexible opportunities for high-throughput membrane studies. Furthermore, the ability to engineer droplet networks within each construct paves the way for "lab-in-a-capsule" approaches accommodating multiple assays per construct and allowing for communicative reaction pathways.

Zinc from oyster tissue as causative factor in mouse deaths in official bioassay for paralytic shellfish poison.

Toxicity (extreme weakness, body temperature drop, cyanosis, some slow deaths) in test mice, upon intraperitoneal injection of standard-method paralytic shellfish poison (PSP) extracts of some PSP-free oysters, is consistent with the relatively high levels of zinc in these extracts. As a rough guideline, the threshold for a toxic response corresponds to a drained tissue zinc level of over 900 micrograms/g. The identification of zinc as the substance responsible has been supported by inducing toxicity in control extracts by spiking with nontoxic levels of zinc, and by eliminating toxicity from toxic extracts by chemical removal (precipitation, ion exchange) of metals.

Herbal remedies of the Maritime Indians: sterols and triterpenes of Achillea millefolium L. (Yarrow).

As part of ongoing studies of the medicinal aspects of Maritime flora, particularly the herbal remedies of the Micmac and Malecite Indians, the sterols and triterpenes of Achillea millefolium L. (Compositae), a widely used herbal remedy known commonly as yarrow, were determined. Using modern techniques, including nuclear magnetic resonance spectroscopy and combined GC-mass spectrometry, beta-sitosterol was identified as the major sterol and alpha-amyrin as the major triterpene of this plant. The sterols stigmasterol, campesterol, and cholesterol and the triterpenses beta-amyrin, taraxasterol, and pseudotaraxasterol were also identified. Successful therapeutic application of yarrow may be partly due to the presence of one or more of these compounds since many sterols and triterpenes exhibit a wide range of pharmacological activities. This is the first reported occurrence of cholesterol, campesterol, and the four triterpenes in yarrow.

Herbal remedies of the Maritime indians: sterols and triterpenes of Tanacetum vulgare L. (Tansy).

Plant sterols and triterpenes exhibit a wide range of pharmacological activities. As part of our ongoing studies of the medicinal aspects of Maritime flora, particularly the herbal remedies of the Micmac and Malecite Indians, we determined the nature of the sterols and triterpenes of Tanacetum vulgare L. (Compositae)-a widely used herbal remedy usually referred to as tansy. By using thin layer and gas chromatographics, nuclear magnetic resonance (NMR) spectroscopy and combined gas chromatography-mass spectrometry, we were able to identify beta-sitosterol as the major sterol and alpha-amyrin as the major triterpene of tansy. We also identified the sterols stigmasterol, campesterol and cholesterol, and the triterpenes beta-amyrin and taraxasterol. A fourth triterpene was tentatively identified as pseudo-taraxasterol. The successful therapeutic application of this herb may be due partly to the presence of one or more of these compounds. The sterols and triterpenes of tansy have not been previously reported; neither, to our knowledge, have the NMR spectra of the amyrins and the NMR and mass spectra of taraxasterol.

Simultaneous determination ofSonchus arvensis L. triterpenes by gas chromatography-mass spectrometry.

Sonchus arvensis L. or sow thistle has proved an excellent source of pentacylic triterpenes; triterpenes account for about 6% of the crude lipid extract or 0.2% of the dried plant. Composition of the triterpenoid fraction, as indicated by gas chromatography of the corresponding acetates, was α-amyrin (9%), ß-amyrin (21%), lupeol (13%), taraxasterol (24%) and pseudo-taraxasterol (12%). A single, long-chain alcohol (16%) was also present. The nature of the triterpenoids was defined using gas chromatography and gas chromatography-mass spectrometry (GC/MS) and confirmed by direct comparison with authentic samples. The use of combined GC/MS proved extremely valuable in the simultaneous analysis of a mixture of triterpene acetates and greatly reduced the time needed to phytochemically evaluate these compounds.

Identification of organochlorine pesticides in crude extracts by mass spectrometry.

A method is described for identifying a chlorinated pesticide in crude extracts (i) at 1 ppm by low resolution mass spectrometry with the aid of a recently developed temperature controlled probe and (ii) at 0.01 ppm by high resolution techniques using a photoplate record to determine the mass deficient ions containing chlorine.This analytical method is feasible wherever ions of the same elemental composition as those derived from an unknown are not otherwise present in the crude extract mass spectrum.