[Diagnostic imaging 2001].
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Diagnostic Imaging↗
Biomedical subjects
K L Pedersen
Publications and source records attributed to K L Pedersen.
Development of an ELISA for vitellogenin in whole body homogenate of zebrafish (Danio rerio).
The yolk protein, lipovitellin (Lv) was purified from ovaries of mature female zebrafish (Danio rerio) by gel filtration and anion exchange chromatography. Polyclonal antibodies against Lv were raised in rabbits. Anti-Lv IgG was purified by affinity chromatography. SDS-PAGE followed by Western blotting was performed to analyse the specificity of the antibody and the immunological similarities between Lv and vitellogenin (Vtg). Anti-Lv IgG was used to develop a direct non-competitive sandwich ELISA to measure Vtg concentrations of whole body homogenate (WBH) in zebrafish. The intra- and interassay variabilities were 5.8% and 10.4%, respectively. The sensitivity was 0.2 ng Vtg x ml(-1) and the practical detection limit was 40 ng Vtg x g(-1) fish (wet weight). Adult male zebrafish were exposed to a nominal water concentration of 10 ng x l(-1) of ethinylestradiol (EE2) in a semi-static exposure system for 7 days. Compared with the control group, exposure to 10 ng EE2 x l(-1) induced a 200-fold increase in Vtg levels.
Animals↗
The preservatives ethyl-, propyl- and butylparaben are oestrogenic in an in vivo fish assay.
The widely used phenolic preservatives ethylparaben, propylparaben, butylparaben and their common metabolite p-hydroxybenzoic acid were tested for their ability to evoke an oestrogenic response in vivo. Yolk protein induction in sexually immature rainbow trout was used as an oestrogen-specific endpoint after repeated injections of the compounds. All tested parabens were oestrogenic in doses between 100 and 300 mg/kg, while the metabolite showed no activity. Ethylparaben was found to be approximately sixty times weaker than propyl- and butylparaben which had oestrogenic potencies comparable to those previously found for bisphenol A.
Animals↗
In vivo estrogenic activity of branched and linear alkylphenols in rainbow trout (Oncorhynchus mykiss).
The in vivo estrogenic activity of the two branched alkylphenols, tert-octylphenol and technical nonylphenol, and the two linear isoforms, n-octylphenol and n-nonylphenol, was compared. The compounds were administered to juvenile rainbow trout (Oncorhynchus mykiss) by either intraperitoneal injection or water exposure and their estrogenic potential was evaluated by ELISA measurements of induced plasma vitellogenin. Intraperitoneal injections (50 mg/kg) of the two branched alkylphenols resulted in a significant vitellogenic response after 12 days whereas no significant induction was seen with the two linear isomers. Water exposure for 9 days to a nominal concentration of 150 micrograms/l of the alkylphenols elicited the same response pattern as seen for the injection experiment. Furthermore, in the present vitellogenin assay tert-octylphenol was giving a higher estrogenic response compared to technical nonylphenol using either of the two exposure routes.
Animals↗
Comparison of short-term estrogenicity tests for identification of hormone-disrupting chemicals.
The aim of this study was to compare results obtained by eight different short-term assays of estrogenlike actions of chemicals conducted in 10 different laboratories in five countries. Twenty chemicals were selected to represent direct-acting estrogens, compounds with estrogenic metabolites, estrogenic antagonists, and a known cytotoxic agent. Also included in the test panel were 17beta++-estradiol as a positive control and ethanol as solvent control. The test compounds were coded before distribution. Test methods included direct binding to the estrogen receptor (ER), proliferation of MCF-7 cells, transient reporter gene expression in MCF-7 cells, reporter gene expression in yeast strains stably transfected with the human ER and an estrogen-responsive reporter gene, and vitellogenin production in juvenile rainbow trout. 17beta-Estradiol, 17alpha-ethynyl estradiol, and diethylstilbestrol induced a strong estrogenic response in all test systems. Colchicine caused cytotoxicity only. Bisphenol A induced an estrogenic response in all assays. The results obtained for the remaining test compounds--tamoxifen, ICI 182.780, testosterone, bisphenol A dimethacrylate, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol dodecylethoxylate, butylbenzylphthalate, dibutylphthalate, methoxychlor, o,p'-DDT, p,p'-DDE, endosulfan, chlomequat chloride, and ethanol--varied among the assays. The results demonstrate that careful standardization is necessary to obtain a reasonable degree of reproducibility. Also, similar methods vary in their sensitivity to estrogenic compounds. Thus, short-term tests are useful for screening purposes, but the methods must be further validated by additional interlaboratory and interassay comparisons to document the reliability of the methods.
DDT↗
Monitoring and risk assessment for endocrine disruptors in the aquatic environment: a biomarker approach.
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Animals↗
Vitellogenin in Zoarces viviparus: purification, quantification by ELISA and induction by estradiol-17 beta and 4-nonylphenol.
Vitellogenin was isolated by gel filtration and ion-exchange chromatography from plasma of estradiol-treated male Zoarces viviparus. The purification of vitellogenin was followed through each step by native polyacrylamide gelelectrophoresis (PAGE). The purified vitellogenin was used to raise anti-vitellogenin antibodies in rabbits. The specificity of the affinity purified antibody raised against vitellogenin was assessed by Western blot analysis. No crossreactivity was observed with plasma from non-induced control males. A direct enzyme-linked immunosorbent assay (ELISA) was developed by use of the raised anti-vitellogenin. The detection limit for the purified standard vitellogenin by the ELISA method was 5 ng ml-1 Vitellogenin levels were quantified in plasma of pregnant female Zoarces viviparus, which were held in aquaria with different concentrations of the estrogenic compound 4-nonylphenol dissolved in the ambient seawater. A marked effect of exposure to ambient 4-nonylphenol was observed by significant dose-dependent increases in the level of plasma vitellogenin of the pregnant fish as well as of embryos exposed in vitro.
Animals↗
Induction and identification of cadmium-, zinc- and copper-metallothioneins in the shore crab Carcinus maenas (L.).
Shore crabs Carcinus maenas were injected with either Cd, Cu or Zn to determine whether different metals could induce specific metallothionein (MT) isoforms in the midgut gland. Furthermore, the relative ability of the three metals to induce MT was quantified. Accumulation of the three metals in the midgut gland caused variable and in the case of Cd and Zn significant increases in MT levels. The increase in MT levels (pmol g-1 midgut gland) per nmol of metal accumulated was determined as 90, 60 and 4 pmol for Cd, Zn, and Cu respectively. The MT isoforms were purified using a combination of acetone precipitation, FPLC and reverse phase HPLC. In contrast to Cd and Zn induced MTs, the Cu induced MT was highly susceptible to oxidation during purification. The induced MT isoforms were characterized by N-terminal amino acid sequencing and mass-spectrometry. All three metals induced the same identical isoform MTIa.
Amino Acid Sequence↗
Primary structures of decapod crustacean metallothioneins with special emphasis on freshwater and semi-terrestrial species.
Cadmium injections induced only a single form of metallothionein (MT) in the midgut gland of Potamon potamios, whereas the same treatment induced two isoforms in Astacus astacus. The only difference between the two latter isoforms was that one had an extra N-terminal methionine residue. MT from P. potamios showed structural differences from other decapod crustacean MTs. It contained a Gly-Thr motif at positions 8 and 8a, which had previously been found only in certain vertebrate and molluscan MTs. Furthermore P. potamios MT contained two to three times as many glutamic acid residues as normally found in decapod crustacean MT. The primary structure of MT from the freshwater crayfish A. astacus showed a high degree of sequence identity with MT from other decapod crustaceans, especially the marine astacidean Homarus americanus, although two valine residues were unexpectedly found at positions 8 and 21, where lysine residues are normally found.
Amino Acid Sequence↗
[Ultrasound and lymphography in malignant lymphoma. Comparison with consideration to staging].
The diagnostic value of abdominal ultrasound and lymphography was compared in the staging of 88 consecutive patients with malignant lymphoma, examined during the period March 1990 to April 1991. Lymphography was used as the reference method in the evaluation of the paraaortic and iliac lymphnodes. In 19% of the patients ultrasound examination could not be accomplished optimally, and these results were evaluated in a separate group. Lymphography demonstrated involvement of retroperitoneal lymphnodes in 27 patients, among these ultrasound was false negative in seven (= 26%). In ten patients ultrasound examination demonstrated lymphoma outside the lymphographic area. No false positive ultrasound examinations were found in the group with negative lymphography. Ultrasound cannot replace lymphography, but is an important supplement, and in those cases where ultrasound reveals lymphomas in the lymphographic area, lymphography can be omitted as ultrasound has a high predictive value.
Abdominal Neoplasms↗
Purification and characterization of a cadmium-induced metallothionein from the shore crab Carcinus maenas (L.).
Two metallothionein variants were purified from the midgut gland of crabs (Carcinus maenas) exposed to a high cadmium concentration (2 p.p.m.). One of the variants was purified from crabs exposed to a low cadmium concentration (0.5 p.p.m.). The purification method involved acetone precipitation, gel filtration and reversed-phase h.p.l.c. The complete amino acid sequences of both variants have been elucidated by m.s. and automated sequence analysis on S-methylated proteins or fragments produced by cleavage of the S-methylated proteins with Staphylococcus aureus proteinase. The two variants from crabs exposed to the high cadmium concentration differed only by a single residue of methionine at the N-terminus. The single variant isolated from crabs exposed to the low cadmium concentration was the one without the N-terminal methionine, indicating that high cadmium concentrations either inhibit the processing enzymes and/or that the processing enzymes cannot keep pace with the increased metallothionein synthesis when cadmium availability is high. Cadmium-induced metallothionein from C. maenas shows a high degree of structural similarity to metallothioneins from the decapod crustaceans Scylla serrata and Homarus americanus.
Amino Acid Sequence↗