Paralytic shellfish poisoning (PSP) toxin binders for optical biosensor technology: problems and possibilities for the future: a review

This review examines the developments in optical biosensor technology, which uses the phenomenon of surface plasmon resonance, for the detection of paralytic shellfish poisoning (PSP) toxins. Optical biosensor technology measures the competitive biomolecular interaction of a specific biological recognition element or binder with a target toxin immobilised onto a sensor chip surface against toxin in a sample. Different binders such as receptors and antibodies previously employed in functional and immunological assays have been assessed. Highlighted are the difficulties in detecting this range of low molecular weight toxins, with analogues differing at four chemical substitution sites, using a single binder. The complications that arise with the toxicity factors of each toxin relative to the parent compound, saxitoxin, for the measurement of total toxicity relative to the mouse bioassay are also considered. For antibodies, the cross-reactivity profile does not always correlate to toxic potency, but rather to the toxin structure to which it was produced. Restrictions and availability of the toxins makes alternative chemical strategies for the synthesis of protein conjugate derivatives for antibody production a difficult task. However, when two antibodies with different cross-reactivity profiles are employed, with a toxin chip surface generic to both antibodies, it was demonstrated that the cross-reactivity profile of each could be combined into a single-assay format. Difficulties with receptors for optical biosensor analysis of low molecular weight compounds are discussed, as are the potential of alternative non-antibody-based binders for future assay development in this area

Quantitative determination of paralytic shellfish poisoning toxins in shellfish using prechromatography oxidation and liquid chromatography with fluorescence detection: interlaboratory study

An interlaboratory study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3 together), gonyautoxins 1 and 4 (GTX1,4 together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2 together), and C-3 and C-4 (C3,4 together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Samples of mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with samples of clams, oysters, and scallops. Twenty-one samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countrie

Golovnojj pedikujoz v detskojj populacii g. Vroclava

As indicated by the data of questionnaires obtained from the environment of children with head pediculosis, as well as by the comparison with control findings, there are significant statistical differences among individual groups, as far as familial, social, economic and hygienic conditions are concerned; this fact suggests that multiple factors may influence the incidence of pediculosis

Magneto-optical studies of iron impurity in HVPE GaN

24th International Conference on Defects in Semiconductors, Albuquerque, NM, JUL 22-27, 2007International audienceWe report on optical studies of bulk GaN crystals doped with iron. High-quality freestanding GaN crystals with varying Fermi level position were grown using the hydride vapor phase epitaxy on bulk GaN substrates. Samples with the dominant neutral Fe3+(3d(5)) acceptor state showed a characteristic near-infrared luminescence band around 1.3 eV, consisting of several sharp lines due to the fine structure of the T-4(1)(G)-(6)A(1)(S) internal transitions of isolated Fe3+ (d(5)) ions. In a magnetic field, these lines split into several components. This allowed us to determine energy structure of the T-4(1), multiplet in the magnetic field. For samples containing a singly ionized Fe2+(3d(6)) acceptor, absorption due to well-resolved E-5-T-5(2) internal transitions of Fe2+ was observed. Measurements performed at different temperatures ranging from 7 to 50 K and at magnetic fields up to 13 T enabled us to analyze some sublevels of the E-5 ground and the T-5(2) excited state. (C) 2007 Elsevier B.V. All rights reserved