Ion-pair extraction of bile acids with Lipidex gel

A new method for the extraction of bile acids from aqueous solutions, urine, plasma, and bile is described. A buffered solution of decyltrimethylammonium bromide is added to the sample to give a 0.03 m concentration of the counter-ion. The mixture is passed through a bed of Lipidex 1000, which is then washed with the buffered solution of counter-ion followed by water. The decyltrimethylammonium salts of bile acids are sorbed by the Lipidex and are eluted with methanol. Recoveries of unconjugated, taurine- and glycine-conjugated, sulfated, and glucuronidated bile acids are close to 100%. Unconjugated bile acids can also be quantitatively extracted from aqueous solutions and urine after acidification with acetic acid.     

Cellular localization of 3H-oestradiol in the hypothalamus

Summary The hypothalamus of male and female rats, given 0.3 g/100 g body weight of 6.7-³H-oestradiol-17 and killed 1 hour after the injection, was examined by autoradiography in order to 1) localize the areas and the cells involved in the uptake of the hormone, and 2) study the intracellular localization of the labelled material.Only nerve cells contained radioactive material while glial and ependymal cells were not significantly labelled. In the anterior hypothalamus, labelled nerve cells were concentrated in areas corresponding to nucleus preopticus medialis and nucleus preopticus, pars suprachiasmatica. The nucleus supraopticus was unlabelled. In the medial basal hypothalamus, neurons corresponding to the nucleus arcuatus and the lateral part of the nucleus ventromedialis showed marked labelling. No significant labelling was observed in the nucleus paraventricularis, pars magnocellularis.Although the individual nerve cells varied in their extent of labelling, the major proportion of the silver grains were consistently concentrated over the nuclei. Castration was not found to influence the results. The findings were essentially the same in male and female rats and appear to suggest that oestradiol exerts a direct effect on nerve cells in certain hypothalamic areas.This work was supported by grants from the Norwegian Cancer Society, Nordisk Insulinfond and Anders Jahres Fond. The skilful assistance of Miss Helga Friedl and Mrs. Jane Larsen is gratefully acknowledged.     

Effect of Processing on the Microflora of Norwegian Seaweed Meal, with Observations on Sporendonema minutum (Høye) Frank and Hess

Meal from the brown seaweed Ascophyllum nodosum (L.) Le Jol. is mainly used as an animal feed supplement. Since moist weed often develops a marked mold growth and since little was known about the microflora of seaweed meal, a cultural procedure was developed to enumerate the populations of bacteria, yeasts, and molds of seaweed meals manufactured by different drying processes. The microflora could be supported by a variety of media varying in levels of nutrition and in the source and concentration of salts. Fresh weed contained less than 10(3) bacteria and less than 10(2) yeasts and molds per g (dry weight). The type and extent of microbial populations in seaweed meal appeared to be dependent upon the method of seaweed drying. Rotary drum-drying at temperatures decreasing from 800 to 80 C maintained or reduced the microbial populations to 10(3) organisms per g (dry weight). Although meals with high nutritional quality can be obtained with warm air- or rock-dried weed, these conditions can also permit bacterial and mold development. Extended rock-drying in variable weather conditions and prolonged storage of moist weed, both of which decrease the nutritional quality, also lead to high bacterial numbers and to a marked development of the halophilic brown mold Sporendonema minutum which attained populations of 10(8) viable spores per g of dried weed. A poultry diet containing 5% badly molded weed had no apparent toxic or growth-depressing effect when fed to chicks.     

Direct Evidence That Excitotoxicity in Cultured Neurons Is Mediated via N-Methyl-D-Aspartate (NMDA) as well as Non-NMDA Receptors

Cultured GABAergic cerebral cortex neurons were exposed to the excitatory amino acid (EAA) L-glutamate, kainate (KA), N-methyl-D-aspartate (NMDA), or RS-alpha-amino-3-hydroxy-5-methyl-4-isoxazolopropionate (AMPA). To ensure a constant glutamate concentration in the culture media during the exposure periods, the glutamate uptake inhibitor L-aspartic acid beta-hydroxamate was added at 500 microM to the cultures that were exposed to glutamate. Each of these EAAs was able to induce neurotoxicity. It was not possible to reduce or prevent glutamate-induced cytotoxicity by blocking only one of the glutamate receptor subtypes with either the NMDA receptor antagonist D-(-)-2-amino-5-phosphonopentanoate (APV) or with one of the specific non-NMDA antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 6,7-dinitroquinoxaline-2,3-dione (DNQX). However, if the cultures were exposed simultaneously to glutamate and the antagonists in combination, i.e., APV plus CNQX or APV plus DNQX, the toxicity was completely prevented. Furthermore, CNQX and DNQX were shown to be selective blockers of cytotoxic phenomena induced by non-NMDA glutamate agonists with no effect on NMDA-induced cell death. Likewise, APV prevented NMDA-induced cell death without affecting the KA- or AMPA-induced neurotoxicity. It is concluded that EAA-dependent neurotoxicity is induced by NMDA as well as non-NMDA receptors.     

Inhibition by excitatory sulphur amino acids of the high-affinityl-glutamate transporter in synaptosomes and in primary cultures of cortical astrocytes and cerebellar neurons

A detailed kinetic study of the inhibitory effects ofl- andd-enantiomers of cysteate, cysteine sulphinate, homocysteine sulphinate, homocysteate, and S-sulpho-cysteine on the neuronal, astroglial and synaptosomal high-affinity glutamate transport system was undertaken.d-[³H] Aspartate was used as the transport substrate. Kinetic characterisation of uptake in the absence of sulphur compounds confirmed the high-affinity nature of the transport systems, the Michaelis constant (K _m) ford-aspartate uptake being 6 M, 21 M and 84 M, respectively, in rat brain cortical synaptosomes and primary cultures of mouse cerebellar granule cells and cortical astrocytes. In those cases where significant effects could be demonstrated, the nature of the inhibition was competitive irrespective of the neuronal versus glial systems. The rank order of inhibition was essentially similar in synaptosomes, neurons and astrocytes. Potent inhibition (K _iK _m) of transport in each system was exhibited byl-cysteate, andl- andd-cysteine sulphinate whereas substantially weaker inhibitory effects (K _i>10–1000 times the appropriateK _m value) were exhibited by the remaining sulphur amino acids. In general, inhibition: (i) was markedly stereospecific in favor of thel-enantiomers (except for cysteine sulphinate) and (ii) was found to decrease with increasing chain length. Computer-assisted molecular modelling studies, in which volume contour maps of the sulphur compounds were superimposed on those ofd-aspartate andl-glutamate, demonstrated an order of inhibitory potency which was, qualitatively, in agreement with that obtained quantitatively by in vitro kinetic studies.Special issue dedicated to Dr. Elling Kvamme     

Clean technology in aquaculture — a production without waste products?

A method has been developed for the determination of H₂S and FeS in sediments. FeS is converted into H₂S which is flushed from the samples directly into an excess of chlorine bleach, NaC1O or KClO with some Zn²⁺ added. Either the excess can be titrated back potentiometrically with As₂O₃, or the sulphate formed can be measured colorimetrically. The precision is primarily controlled by the homogeneity of the sediment suspensions and can be better than 99%.     

A cladistic analysis ofAnisopappus (Asteraceae: Inuleae)

A cladistic analysis of the genusAnisopappus (Asteraceae: Inuleae) has been undertaken. A hypothesis of species interrelationships in the genus is presented for the first time. The analysis also includedArctotis (Arctoteae), used as outgroup, and five additional genera from theInuleae: Geigeria, Calostephane, Asteriscus, Buphthalmum, Pulicaria, andInula. It is concluded thatAnisopappus is a monophyletic group situated at the base of the tribe, diagnosed by, e.g., their obtuse stylar sweeping-hairs. The species with acute sweeping-hairs were found to be derived within the genus. Problems concerning species delimitation, biogeography and character evolution in the genus are briefly discussed.     

Colonial breeding and speciation in birds

Summary It was recently suggested that bird species which breed colonially might be under stronger sexual selection, have faster rates of evolution and might therefore speciate more rapidly than bird species which do not. If true, then colonial taxa should contain more species than non-colonial taxa, other things being equal. When similarity through common descent is accounted for, there is little evidence for an association between the number of species in a clade and whether it is colonial or not.     

The Gene for Human Glutaredoxin (GLRX) Is Localized to Human Chromosome 5q14

Glutaredoxin is a small protein (12 kDa) catalyzing glutathione-dependent disulfide oxidoreduction reactions in a coupled system with NADPH, GSH, and glutathione reductase. A cDNA encoding the human glutaredoxin gene (HGMW-approved symbol GLRX) has recently been isolated and cloned from a human fetal spleen cDNA library. The screening of a human genomic library in Charon 4A led to the identification of three genomic clones. Using fluorescencein situhybridization to metaphase chromosomes with one genomic clone as a probe, the human glutaredoxin gene was localized to chromosomal region 5q14. This localization at chromosome 5 was in agreement with the somatic cell hybrid analysis, using DNA from a human–hamster and a human–mouse hybrid panel and using a human glutaredoxin cDNA as a probe.     

Narthecium ossifragum Associated Photosensitization in Sheep in The Faroe Islands

Hepatogenous photosensitization in sheep is an important problem in various parts of the world. Most photosensitization diseases are associated with ingestion of plant or fungal toxins. The lily, Narthecium ossifragum, has long been associated with photosensitization in lambs in western Norway (Ender 1955, Flåøyen 1993) and in the northern regions of the British Isles (Ford 1964).