Norwegian Defence Research Establishment

About: Norwegian Defence Research Establishment is a facility organization based out in Oslo, Norway. It is known for research contribution in the topics: Glutamate receptor & Radar. The organization has 1288 authors who have published 2262 publications receiving 62382 citations. The organization is also known as: Forsvarets forskningsinstitutt & FFI.

A rapid radiochemical method for the determination of choline acetyltransferase.

Abstract: RADIOCHEMICAL assays of choline acetyltransferase (ChAT) must be based on reproducible, rapid and specific procedures for isolating ACh from the incubation mixture. In our laboratory this has been achieved by isolating labelled ACh by liquid cation exchange using sodium tetraphenylboron (Kalignost) in ethyl butyl ketone (FONNUM, 1969a. b). In the present report I will show that this method can be simplified considerably by using the scintillation mixture as extraction solvent and carrying out the extraction directly in the scintillation vial. Labelled ACh can subsequently be determined by liquid scintillation counting at high efficiency in the biphasic aqueous: toluene scintillation solution mixture. The principle involved would be applicable to other radiochemical enzyme assays based on different forms of organic solvent extraction such as in methods for AChE (POTTER, 1967) and aromatic amino acid decarboxylase (BROCH & FONNUM, 1972). Particular attention has been paid to the possible interference of acetylcarnitine in the assay of ChAT and the effect of acetyl-CoA concentration on the ChAT activity.

Glutamate: a neurotransmitter in mammalian brain.

Abstract: Glutamate is ubiquitously distributed in brain tissue, where it is present in a higher concentration than any other amino acid. During the last 50 years glutamate in brain has been the subject of numerous studies, and several different functions have been ascribed to it. Early studies by Krebs (1935) suggested that glutamate played a central metabolic role in brain. The complex compartmentation of glutamate metabolism in brain was first noted by Waelsch and coworkers (Berl et al., 1961). These studies were precipitated by the claim that glutamate improved mental behaviour and was beneficial in several neurological disorders including epilepsy and mental retardation. Other scientists pointed out its function in the detoxification of ammonia in brain (Weil-Malherbe, 1950). Glutamate is also an important building block in the synthesis of proteins and peptides, including glutathione (Meister, 1979). The toxic effect of administered glutamate and its analogues kainic acid, ibotenic acid, and N-methyl aspartic acid on CNS neurones has become a large and independent line of research (Lucas and Newhouse, 1957; Olney et al., 1974; Lund-Karlsen and Fonnum, 1976; Coyle, 1983). Attention has also been focused on the role of glutamate as a precursor for the inhibitory neurotransmitter y-aminobutyric acid (GABA) (Roberts and Frankel, 1950). Electrophysiological studies (Curtis and Watkins, 1961) focused early on the powerful and excitatory action of glutamate on spinal cord neurones. Since the action was widespread and effected by both the Dand Lforms, it was at first difficult to believe that glutamate could be a neurotransmitter. During the last 15 years, however, several studies have provided support for the concept that glutamate is a transmitter in brain (for review see Curtis and Johnston, 1974; Fonnum, 1978; 1981; Roberts et al., 1981; DiChiara and Gessa, 1981). Glutamate satisfies today to a large extent the four main criteria for classification as a neurotransmitter: (1) it is presynaptically localized in specific neurones; (2) it is specifically released by physiological stimuli in concentrations high enough to elicit postsynaptic response; (3) it demonstrates identity of action with the naturally occurring transmitter, including response to antagonists; and (4) mechanisms exist that will terminate transmitter action rapidly. The evidence for glutamate as a transmitter at the locust neuromuscular junction has recently been carefully evaluated by Usherwood (1981). In that case the identity of action of glutamate with the naturally occurring transmitter on the neuromuscular receptor, the release from nerve terminals, and its similarity to acetylcholine at the mammalian neuromuscular junction with regard to presynaptic pharmacology and denervation supersensitivity are compelling evidence for glutamate as a neurotransmitter. The main methods used to identify glutamergic pathways in brain will be critically reviewed and discussed. The effect of lesions on high-affinity uptake and release are particularly important, but immunohistochemical methods to study enzymes and glutamate itself are becoming more interesting. The release of glutamate has been demonstrated by several different procedures using both in vivo and in vitro preparations. The synthesis of large groups of specific agonists and antagonists has been important both for identification and characterization of the glutamate receptor by electrophysiological techniques and for the isolation of glutamate receptors. High and perhaps low-affinity uptake into nerve terminals and glial cells is important for the termination of transmitter action. Particular attention is given in this review to the complex compartmentation of glutamate synthesis and the possibility of identifying the transmitter pool of glutamate.

Isolation of lymphocytes, granulocytes and macrophages.

Abstract: This paper presents the standard procedure for isolating lymphocytes and granulocytes from blood, using the Isopaque-Ficoll technique. A procedure for isolating granulocytes and macrophages from peritoneal fluid is also described.

Cloning and expression of a rat brain L-glutamate transporter.

Abstract: SYNAPTIC transmission of most vertebrate synapses is thought to be terminated by rapid transport of the neurotransmitter into presynaptic nerve terminals or neuroglia1–5. L-Glutamate is the major excitatory transmitter in brain and its transport represents the mechanism by which it is removed from the synaptic cleft and kept below toxic levels5,6. Here we use an antibody against a glial L-glutamate transporter from rat brain7 to isolate a complemen-tary DNA clone encoding this transporter. Expression of this cDNA in transfected HeLa cells indicates that L-glutamate accumulation requires external sodium and internal potassium and transport shows the expected stereospecificity. The cDNA sequence predicts a protein of 573 amino acids with 8–9 putative transmembrane α-helices. Database searches indicate that this protein is not homologous to any identified protein of mammalian origin, including the recently described superfamily of neurotransmitter transporters. This protein therefore seems to be a member of a new family of transport molecules.

The Dalton quantum chemistry program system

Abstract: Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, confi ...