Hepatic coma and amino acids in the nerve endings of the central nervous system

The levels of amino acids in the cerebral cortex and synaptosomes of 6 autopsied patients who had died of chronic liver diseases with portasystemic shunt were examined and compared with those of controls. The level of threonine in the cerebral cortex and synaptosomes of the 6 patients, who had developed hepatic coma before death, was significantly higher than that of 9 patients without hepatic coma. However, the levels of the neurotransmitters, aspartate, glutamate, and glycine, showed no significant difference between the two groups. In animal experiments, threonine uptake into the synaptosomes was enhanced by an increase of threonine concentration in the cerebral cortex, and at the same time ammonia further promoted threonine uptake. The high level of threonine in the synaptosomes was released just like a neurotransmitter on potassium stimulation in the patients with hepatic coma. Since threonine has no post-synaptic action, it is thought that threonine released in this way somehow interferes with brain action. This phenomenon may play an important role in the development of hepatic coma.     

Changes in the amounts of chlorogenic and caffeic acids during tobacco seed maturation

During maturation of tobacco seed, the amount of chlorogenic acid rapidly increased between days 7 and 11 after anthesis and then decreased until day 15. Chlorogenic acid was not detected in fully mature seed. On the other hand, caffeic acid appeared from day 15, reached a maximum at day 21, and rapidly disappeared by day 25 although the amount was always low in comparison with that of chlorogenic acid. Changes in dry wt, water content, testa color and germination of tobacco seeds during maturation were also investigated. The results suggested that there were rapid biochemical changes in seed between days 11 and 15 after anthesis.     

The release of amino acids from nerve during stimulation

Frog sciatic nerves were incubated for 24 hours in either glycine, aspartic acid, glutamic acid, lysine, leucine, γ-aminobutyric acid, glutamine, or pentanedioic acid (all labeled with C¹⁴), and the rates of release of these compounds were monitored under resting conditions and during stimulation. Upon stimulation, the rate or release of glutamic acid increased an average of 200% above the resting rate. This extra release is highly specific with regard to molecular size and structure, since of the compounds tested only glutamic acid gave significant increases in rates of release during stimulation. Ouabain (0.1 mM) had no effect on the rate of release; however, sodium azide (0.2 mM or 1.0 mM) completely eliminated the extra release during excitation, indicating that the increased permeability to glutamic acid is energy-dependent. Competition experiments show that the extra release of glutamic acid can be eliminated with 10 mM concentrations of non-isotopic choline. The hypothesis is advanced that glutamic acid is actively extruded by a highly specific carrier mechanism.     

Thin-layer chromatography of sub-nanomole amounts of phenylthiohydantoin (PTH) amino acids on polyamide sheets

Thin-layer chromatography of PTH amino acids on polyamide sheets with a fluorescent indicator gave a 50–100-fold increase in sensitivity when compared to thin-layer polyamide plates developed by spray techniques. Resolution of the individual residues in a standard mixture remains comparable to that described previously. Using this technique, the two-dimensional chromatography of each residue from automated sequence analysis is quite feasible even when small amounts of material are available.     

Changes in amino acids and protein metabolism in Egyptian cobra (Naja haje) during hibernation

1. 1.Total protein, GOT, GPT, alkaline phosphatase and total free amino acid content in the brain, liver and kidney were studied in the hibernating, arousing and normothermic cobra (Naja haje).

2. 2.Tissues showed a decline in protein content which started in the prehibernating animals. At the low body temperatures in hibernation both synthesis and degradation would be reduced. The fall in protein content suggests synthesis is reduced more steeply than is degradation. Recovery of protein biosynthesis was demonstrated during arousal.

3. 3.In aroused animals, the levels of free amino acids in the tissues examined were higher than in hibernating ones or in normothermic controls studied in summer.

4. 4.A decline in GOT activity was recorded in the hibernating animals. The enzyme activity showed recovery on arousal. A similar trend was observed for the GPT activity in brain and kidney.

5. 5.The activity of alkaline phosphatase was also examined in the different tissues. The correlation of these changes to the different phases of hibernating cycle is discussed.

Changes in free amino acids in Alphitobius diaperinus (Coleoptera: Tenebrionidae) during thermal and food stress

Temporal changes in free amino acid pools are examined in starved and cold-exposed (10 degrees C) beetles (Alphitobius diaperinus) (control beetles; 4, 7, 14, 28 and 56 days of cold-exposure). The range of individual responses and the effect of gender on survival and free amino acid levels are evaluated. Females survived significantly longer (Lt50 and Lt90) than males under stressing conditions. Pro, Gln, Ala, Arg and Thr are the major components of the free amino acid pool in the whole body of adult beetles. Multivariate analysis indicates that the duration of exposure explains most of the observed variation in amino acid levels, while sex effect is not significant. Moreover, amino acid levels fluctuate strongly within each sampled date, revealing a high inter-individual heterogeneity. However, this heterogeneity decreases after four weeks of cold-exposure and starvation. The increase in Ala level and the concomitant decrease of Pro after four weeks suggest that Pro might be an important fuel for metabolism when fat reserves are reduced. We conclude that changes in free amino acid pools are due to a combination of reduced individual heterogeneity, cold-acclimation and amino acid degradation for energetic purposes.     

Changes of free amino acids in media during the culture of mosquito cells

The utilization of free amino acids in culture media by two mosquito cell lines derived from Aedes aegypti (Peleg, 1969) and Culex molestus (Kitamura, 1970), were studied. Amino acids which showed a marked decrease with increasing period of culture were aspartic acid, cystine, and ornithine in both cell lines. Asparagine and glutamine decreased markedly in Culex cell culture, but only slightly in Aedes cell culture. In contrast isoleucine, leucine, proline, tyrosine and valine decreased more in the Aedes cell culture than in the Culex cell culture. Arginine, glycine, lysine, phenylalanine, serine, threonine and tryptophan did not change significantly in the culture media of either cell lines. α-Alanine increased markedly in the culture of both cell lines. Glutamic acid increased to some extent in the Culex cell culture, but not in the Aedes cell culture. β-Alanine and histidine increased slightly in the Aedes cell culture, whereas they remained almost unchanged in Culex cell culture.     

Changes in amino acids and lipids during embryogenesis of European lobster, Homarus gammarus (Crustacea: Decapoda)

We studied the amino acid and lipid dynamics during embryogenesis of Homarus gammarus. Major essential amino acids (EAA) in the last stage of embryonic development were arginine, lysine and leucine; major nonessential amino acids (NEAA) were glutamic acid, aspartic acid, valine and glycine. The highest percent of utilization occurred in respect to EAA (27.8%), mainly due to a significant decrease (p<0.05) of methionine (38.3%) and threonine (36.0%). NEAA also decreased significantly (p<0.05, 11.4%), namely serine (38.1%), tyrosine (26.4%) and glutamic acid (25.7%). In contrast, the free amino acid content increased significantly (p<0.05) during embryonic development, especially the free nonessential amino acids (FNEAA). In the last stage, the most abundant FNEAA were glycine, proline, alanine and taurine, and the major free essential amino acids (FEAA) were arginine, lysine and leucine. Lipid content decreased significantly (p<0.05) during embryonic development. A substantial decrease in all neutral lipid classes was observed (>80% of utilization). Major fatty acids were 16:0, 18:0, 18:1n-9, 18:2n-6, 18:3n-3, 20:5n-3 and 22:6n-3. Unsaturated (UFA) and saturated fatty acids (SFA) were used up at similar rates (76.5% and 76.3%, respectively). Within UFA, monounsaturates (MUFA) were consumed more than polyunsaturates (PUFA) (82.9% and 67.5%, respectively).     

Changes in the amino acids content of almond buds during their hibernation and development

Auto?i p?edkládají výsledky chromatografického stanovení volných aminokyselin a aminokyselin bílkovinných frakcí rozpustných v ethanolu a louhu, a nerozpustných, v květních a vegetativních pupenech dvou r?zně v??i zimě odolných odr?d mandloně Non-plus-ultra a Voch?aberdi, odebraných v r?zn?ch termínech od podzimu do jara. Chromatografické stanovení aminokyselin v pupenech ukázalo :

1. 1.
   V květních a vegetativních pupenech se projevuje béhem podzimu a zimy dosti dob?e pozorovatelný rozdíl v obsahu a poměru aminokyselin skoro v?ech frakcí. Nejvýrazněj?í rozdíl se projevuje v kvalitativním obrazci a poměru volných aminokyselin a aminokyselin frakcí rozpustnych v ethanolu, slaběji u frakcí rozpustnych v louhu a nerozpustných.     
   
   

Changes with aging in the levels of amino acids in rat CNS structural elements I. Glutamate and related amino acids

Glutamate and related amino acids were determined in 53 discrete brain areas of 3-and 29-month-old male Fischer 344 rats microdissected with the punch technique. The levels of amino acids showed high regional variation-the ratio of the highest to lowest level was 9 for aspartate, 5 for glutamate, 6 for glutamine, and 21 for GABA. Several areas were found to have all four amino acids at very high or at very low level, but also some areas had some amino acids at high, others at low level. With age, in more than half of the areas, significant changes could be observed, decrease occurred 5 times more frequently than increase. Changes occurred more often in levels of aspartate and GABA than in those of glutamate or glutamine. The regional levels of glutamate and its related amino acids show severalfold variations, with the levels tending to decrease in the aged brain.     

Stereoselective routes towards the synthesis of unusual bis(amino acids) and cyclic amino acids

Stereoselective syntheses are described of bridged bis(glycines) as conformationally constrained substitutes for cystine, and of cyclic -amino acids where the -carbon of the amino acid is part of a five-, six- or seven-membered ring which may hold a hydroxy group as a threonine analogue.