[Formation of alpha-aminobutyric acid in Clostridium sordellii]. / Die Bildung von alpha-Aminobuttersäure in Clostridium sordellii.

After a modified growth C. sordellii is able to ferment threonine as mono-substrate. It could be demonstrated for the first time that alpha-aminobutyric acid is definitely formed from threonine by clostridia. The pH-optimum of this reaction is greater than 8, the temperature optimum is greater than 28 degrees C. Further fermenting products are: glycine and presumably acetaldehyde.

Synthesis of [3H]2-amino-4-phosphonobutyric acid and characterization of its binding to rat brain membranes: a selective ligand for the chloride/calcium-dependent class of L-glutamate binding sites.

[3H]2-amino-4-phosphonobutyric acid was synthesized by the conjugate addition of 1-lithio-2-trimethylsilyethyne to diethyl ethynylphosphate followed by catalytic tritiation and hydrolysis. Radiolabelled 2-amino-4-phosphonobutyric acid binds to a distinct class of L-glutamate binding sites and does not exhibit appreciable binding to sites not displaced by L-glutamate. The binding affinity (Kd = 5.1 +/- 0.4 microM) and pharmacological profile correspond to those values obtained from physiological studies of 2-amino-4-phosphonobutyric acid inhibition of synaptic transmission, and to those values obtained in [3H]L-glutamate binding assays. [3H]2-amino-4-phosphonobutyric acid does not exhibit significant binding to the Cl-/Ca2+-independent L-glutamate binding site(s), nor to the Na+-dependent L-glutamate binding site (up to 50 mM Na+). These data provide further evidence that the physiological action of 2-amino-4-phosphonobutyric acid is mediated by the previously described Cl-/Ca2+-dependent L-glutamate binding sites, and provides an assay system which is optimal for the study of these sites.

Studies on the formation of gamma-aminobutyric acid from putrescine in rat organs and purification of its synthetic enzyme from rat intestine.

The formation of gamma-aminobutyric acid (GABA) from putrescine was examined in organs of rats using radioactive putrescine. Radioactive GABA was detected in all the organs of a rat injected intraperitoneally with radioactive putrescine, and the highest radioactivity of GABA was observed in the small intestine. The enzyme involved in this formation was purified from small intestine and identified as a diamine oxidase, histaminase, from the properties of the enzyme. Activity of the enzyme was found in all the organs of rat, and the highest activity was observed in the small intestine.

Possible role of gamma-aminobutyric acid synthesis in the mechanism of dexamethasone feedback action.

Specific inhibition of glutamic acid decarboxylase (GAD, EC 4.1.1.15; the main enzyme involved in the synthesis of gamma-aminobutyric acid) by mercaptopropionic acid interferes with the effect of dexamethasone on both the resting and stress-induced secretion of ACTH. It is postulated that dexamethasone may, at least in part, inhibit the secretion of ACTH via the induction of GAD, thereby raising the level of gamma-aminobutyric acid in the central nervous system.

Centrally-acting drugs and the formation of brain gamma-aminobutyric acid.

1. The effects of a number of centrally-acting compoinds were tested on the levels of GABA and glutamate and on the formation of GABA from glutamate in rat brain. 2. Pargyline and desipramine increased the brain concentration of GABA but were without effect on GABA production. 3. Imidazoleacetic acid increased GABA levels, decreased glutamate levels but did not alter GABA production, whereas gamma-hydroxybutyric acid had an effect only on GABA formation. 4. Isonicotinc acid hydrazine caused a marked decrease in the formation of GABA from glutamate. 5. Chlorpromazine, diphenylhydantoin, bicucculine, and L-DOPA had no effect on any of the biochemical parameters measured. 6. The central effects of these drugs are discussed in relation to the above findings.

Development of a clonal myogenic cell line with unusual biochemical properties.

The morphological, ultrastructural, biochemical and electrophysiological properties of B104-F, a clonal cell line derived from a nitrosoethylurea-induced neoplasm in a rat, were studied as a function of the growth phase of the culture. Cells in exponentially growing cultures are mononucleate and produce action potentials when stimulated electrically. Stationary phase cultures contain three types of cells: cells of the first type are mononucleate and have long processes containing microfilaments and many parallel microtubules; cells of the second type are mononucleate but contain no microtubules and few microfilaments; and cells of the third type have ultrastructural features typical of multinucleate, striated myotubes. Multinucleate cells generate action potentials with both sodium and calcium components and are depolarized by acetylcholine. The acetylcholine response is blocked by d-tubocurarine. The specific activity of creatine phosphokinase is nine times higher in stationary phase cultures than in exponentially growing ones while the myokinase specific activity is unchanged. The gamma-aminobutyric acid content of the cells is 3.5- to 26-fold higher in stationary phase than in exponentially growing cultures, depending on the degree of fusion of the culture. The properties of B104-F are discussed in relation to the properties of developing skeletal muscle and of central nervous system cell lines.

Formation of glutamate and GABA in epileptogenic tissue from human hippocampus in vitro.

The levels of some amino acids and the incorporation rates of 14C from glucose and acetate were estimated in control human brain tissue and epileptogenic foci from human hippocampus incubated in glucose-saline medium. In the epileptogenic tissue the level of glutamine and the incorporation of radioactivity from both substrates into glutamine were lowered, mainly from acetate. These results suggest damaged glial metabolism. The relative increase of glutamate and decrease of glutamate formation in epileptogenic tissue were similar to the changes caused in rat brain slices by increased concentration of potassium in the incubation medium.

[Variety of effects of vitamins on yeast cells in aerobic conditions]. / O raznostoronnosti deistviia vitaminov na drozhzhevye kletki v aerobnykh usloviiakh

The effect of thiamine and biotin on the processes of cell division, assimilation of glucose, and accumulation of the biomass and nitrogen in the cells was studied with the Candida yeast. The action of the vitamins depended on the source of nitrogen. In some strains, asparagine can substitute for biotin. Biotin has different effect on the production of gamma-aminobutyric acid in Candida pulcherrima, C. guilliermondii. C. tropicalis K3-10. High concentrations of arginine were found in C. guilliermondii var. membranaefaciens in the presence of biotin. The vitamins did not favour the assimilation of nitrate nitrogen in species which were not adapted to this source of nitrogen.