Found: 7010 publications , showing page 338 of 585
Scientific paper
Paraquat and menadione exposure of rainbow trout (Oncorhynchus mykiss) – Studies of effects on the pentose-phophate shunt and thiamine levels in liver and kidney
Possible xenobiotic interactions with thiamine were studied in salmonid fish, by repeatedly injecting two model substances, paraquat and menadione, into juvenile rainbow trout (Oncorhynchus mykiss). These two substances were chosen because of their well-known ability to redox-cycle and cause depletion of NADPH in several biological systems. Depletion of NADPH increases metabolism through the pentose-phosphate shunt and may thereby increase the need for thiamine diphosphate by heightened transketolase activity. A special food was produced with lower thiamine content than commercial food, usually enriched with thiamine, which could mask an effect on the thiamine level. After 9 weeks of exposure, glucose-6-phosphate dehydrogenase, transketolase, glutathione reductase and ethoxyresorufm O-deethylase were analysed in liver and kidney cellular sub-fractions as well as analysis of total thiamine concentrations in liver, kidney and muscle. The results showed that paraquat caused a large increase in hepatic glutathione reductase activity and induced hepatic glucose-6-phosphate dehydrogenase activity, i.e., the rate-limiting enzyme in the oxidative part of the pentose-phosphate shunt. Despite this paraquat exposure did not affect transketolase activity and total thiamine concentration.
Scientific paper
A field survey of chemicals and biological products used in shrimp farming.
Rapid determination of lidocaine solutions with non-column chromatographic diode array UV spectroscopy and multivariate calibration
K. Wiberg, Hagman A, S P. Jacobsson
2003
| 30(5)
(1575-1586)
A new method for the rapid determination of pharmaceutical solutions is proposed. A conventional HPLC system with a Diode Array Detector (DAD) was used with no chromatographic column connected. As eluent, purified water (Milli Q) was used. The pump and autosampler of the HPLC system were mainly utilised as an automatic and convenient way of introducing the sample into the DAD. The method was tested on the local anaesthetic compound lidocaine. The UV spectrum (245–290 nm) from the samples analysed in the detector was used for multivariate calibration for the determination of lidocaine solutions. The content was determined with PLS regression. The effect on the predictive ability of three factors: flow, data-collection rate and rise time as well as two ways of exporting a representative UV spectrum from the DAD file collected was investigated by means of an experimental design comprising 11 experiments. For each experiment, 14 solutions containing a known content of lidocaine were analysed (0.02–0.2 mg ml−1). From these 14 samples two calibration sets and two test sets were made and as the response in the experimental design the Root Mean Square Error of Prediction (RMSEP) values from the predictions of the two test sets were used. When the factor setting giving the lowest RMSEP was found, this setting was used when analysing a new calibration set of 12 lidocaine samples (0.1–0.2 mg ml−1). This calibration model was validated by two external test sets, A and B, analysed on separate occasions for the evaluation of repeatability (test set A) and determination over time (test set B). For comparison, the reference method, liquid chromatography, was also used for analysis of the ten samples in test set B. This comparison of the two methods was done twice on different occasions. The results show that in respect of accuracy, precision and repeatability the new method is comparable to the reference method. The main advantages compared with liquid chromatography are the much shorter time of analysis (
Scientific paper
On-line infrared detection in aqueous micro-volume systems
M. Kölhed, B. Lendl, B. Karlberg
2003
| 128(1)
(2-6)
Mid infrared spectroscopy is a non-destructive technique that can provide detailed information on important, molecule-specific features such as the conformation and functional groups of a large range of compounds. Infrared spectroscopy is now an established and frequently used technique for qualitative analysis, i.e. the identification of chemical constituents in a sample. In addition, its use for quantitative purposes has grown dramatically in recent years. It is important to realise that the analytical problem defines the mode of operation and implementation of the FTIR technique. This Highlight article focuses on the advantages and scope of on-line FTIR detection strategies. However, in common with all techniques, on-line FTIR detection has a number of potential shortcomings, which are also discussed.
Presentation abstract
Will Sweden reach set targets in 2005 and 2010?.
Johansson, C.
2003
CAFE workshop on Second particulate matter position paper.
Models of the distribution of persistent organic pollutants in the marine environment
Persson, NJ.
2003
| Dep of Systems Ecology, SU
| ISBN: 91-7265-665-4
Scientific paper
Sulfurization of carbohydrates results in a S-rich, unresolved complex mixture in kerogen pyrolysates.
van Dongen, B.E.; Schouten, S.; Sinninghe Damsté, J.S.
2003
| Energy Fuels
| 17
(1109-1118)
Technical report
Critical limits for cadmium, lead and mercury related to ecotoxicological effects on soil organisms, aquatic organisms, plants, animals and humans. In: … United Nations UN/ECE-CLRTAP, UBA-Texte 47/03, pp. 29-78. (ISSN, http://www.icpmapping.org)
de Vries, W.; Schütze, G.; Lofts, S.; Meili, M.; Römkens, P.; Farret, R.; de Temmerman, L.; Jakubowski, M.