Synthesis of analogues of GABA. X. The bicyclic β-diketone Octahydro-1H-2-pyrindine-5,7-dione

The synthesis is described of octahydro-1H-2-pyrindine-5,7-dione (4) and its 6-diazo and 6-bromo derivatives. These are analogues of GABA in which the carboxyl group is replaced by an enolic β-diketone. The compounds showed negligible or very weak activity as GABA agonists with respect to inhibition of [3H] GABA binding, uptake and transamination in rat brain membranes.

Structure of the human erythrocyte blood group P1 glycosphingolipid

A glycosphingolipid with blood group P1 activity was extracted from an acetone powder of human erythrocyte stroma with chloroform-methanol. It was purified by chromatography on columns of silicic acid and by preparative thin-layer chromatography of the fully acetylated and deacetylated glycolipid. The purified glycolipid contained galactose, N-acetylglucosamine, and glucose in a molar ratio of 3:1:1. Treatment of the P1 glycolipid with fig alpha-galactosidase released a single galactosyl residue and destroyed the blood group activity, and the alpha-galactosidase product had the same chromatographic mobility as paragloboside. Substitution sites on the neutral sugars of the P1 glycolipid and the alpha-galactosidase product were established by identification of methylated alditol acetates, and substitution on N-acetylglucosamine was determined by identification of methyl glycoside derivatives. The terminal nonreducing disaccharide of the P1 glycolipid is Gal(alpha, 1 leads to 4)Gal. N-Acetylglucosamine was identified as the next sugar in sequence by mass spectrometric analysis of the permethylated P1 glycolipid. On the assumption that the glucose residue is linked to ceramide, we propose the following structure for the P1 glycolipid: Gal(alpha, 1 leads to 4)Gal(beta, 1 leads to 4)Glc-NAc(beta, 1 leads to 4)Glc-Cer.

Mouse salivary gland virus plaque assay on a stable line of mouse embryo cells

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THE EFFECT OF SODIUM CHLORIDE ON PHAGE FORMATION BY STAPHYLOCOCCI AT ELEVATED TEMPERATURES

In experiments with the K strain of Staphylococcus aureus and the K race of bacteriophage suspended in tryptose phosphate broth and maintained at 42°C. it was found that the presence of 1 M NaCl produced certain drastic changes in the relationship between the host cells and the infecting virus: 1. Staphylococci grown at 42°C. in plain broth or in NaCl-broth are "activated," i.e. when growth is stopped by lowering the temperature to 5°C. and phage is added, the activity titre immediately displays a rise of 15- to 16-fold. 2. 1 M NaCl tends to prevent the sorption of phage by cocci and this effect is more pronounced at 42°C. than at 5°C. When the activation test is conducted at 5°C. (the usual temperature) most of the phage is picked up by the cells and the described increase in activity titre follows. If the test takes place at 42°C. there is little sorption and correspondingly little rise in phage titre. 3. Mixtures of staphylococci and phage incubated at 42°C. in NaCl-broth fail to produce phage; the final plaque and activity titres are identical with the initial titres. Here, also, the influence of 1 M NaCl in preventing contact of phage with cocci appears to account for the results. 4. Similar mixtures held at 42°C. in plain broth exhibit a drop of about 60 per cent in activity and plaque titres. The loss of phage may be due to adsorption on dead cells accumulating in the suspension or to the thermolability of the bacterium-phage complex, or to both.