Amount Of Glu Research Articles

A facile cell-involved microfluidic platform for assessing risk of hepatotoxic chemicals via on-line monitoring of multi-indexes

Toxicity assessment is necessary in many fields, but the common animal experiments and traditional cell-based bioassays are endpoint tests and limited in the aspects of cost, complex operation, individual difference, etc. Herein, a cell-involved platform for facilely assessing risk of chemicals was established based on electrochemical biosensing and microfluidic technology. Through in situ monitoring responses of live cells cultivated in sensor chamber towards exterior chemical stimuli, a preliminary categorization of chemicals on reversibility of cell injury has been achieved. The device consists of two core units: a bioreactor and a cell metabolism monitoring chip (CMMC). The bioreactor is for culturing live cells and meanwhile delivering real-time electrochemical impedance of cells via a built-in interdigital electrode. The CMMC is connected to the bioreactor and the installed enzymatic screen-printed electrodes (SPEs) fulfill on-line detection of glucose (Glu) and lactic acid (LA) flowing out of the bioreactor. Impedance values have to do with cell growth and reproduction, while the amounts of Glu and LA reflect respiration state of cells. To test validity of the platform, HepG2 cells were cultured in the bioreactor and treated with five chemicals. The influence induced by these chemicals was studied by monitoring and analyzing the variations of three signals (cell adhesion, Glu uptake and LA generation). The whole system allows for preliminary understanding of toxicity and possible mechanism of chemicals acting on cells, which is also expected to be applied in varied fields including ecological safety, biomedicine, etc.

Type 1 diabetes alters astrocytic properties related with neurotransmitter supply, causing abnormal neuronal activities

Glutamine synthetase (GS), an astrocytic protein in the brain, mediates the process by which glutamate (Glu) is transformed into glutamine (Gln) during Glu and gamma-aminobutyric acid (GABA) de novo synthesis. There are many types of neural complications related with those neurotransmitters in type 1 diabetes (T1D) patients, but there is little information about the change GS. Therefore, we examined changes in GS activity and expression, as well as the amount of Glu, Gln, and GABA in the brain of a T1D animal model. Using primary culture we found that glucose fluctuation caused glial fibrillary acidic protein (GFAP) and GS changes but constant high glucose level didn׳t. In T1D mouse, GS expression increased in the prefrontal cortex (PFC) and hippocampus (HI), but decreased GS activity was only observed in the HI whereas GFAP expression decreased in both regions. Gln increased in both regions, but Glu and GABA were only increased in the HI of T1D animals where GS activity decreased with higher reactive oxygen/nitrogen species. Collectively, low GS activity may be closely related with high levels of Glu and GABA in the HI of T1D brain, and this would result in abnormal neurotransmissions.

Gamma-aminobutyric acid and glutamic acid contents, and the GAD activity in germinated brown rice (Oryza sativa L.): Effect of rice cultivars

The γ-aminobutyric acid (GABA) and glutamic acid (Glu) contents, and the glutamate decarboxylase (GAD) activity in brown rice (BR) and germinated BR (GBR) of the 5 Thai rice cultivars KDML105, PT1, CN1, SP1, and PL2 were investigated. BR was soaked at 35°C for 12 h and then germinated for 24 h to produce GBR. Amounts of GABA and Glu, and the GAD activity in samples were determined. The GABA content and GAD activity in GBR samples of all cultivars were increased 7–50× and 10–100× over levels in BR. The GABA content in BR had no effect on GABA accumulation in GBR. There was no trend in changes in the Glu content for different cultivars after soaking and germination. Variation in the GABA amount in GBR was due to both the GAD activity and the amount of Glu. These two parameters affected accumulation of GABA in all cultivars.

Umami in wine

The positive effects of umami on flavour are widely documented, but as far as the author is aware, wines are not mentioned in umami-related literature; vice versa, in wine-related scientific publications, references to umami were not found. In the fermentation and subsequent ageing of wines there is ample opportunity for umami compounds to develop. Umami refers to the taste of free glutamic acid (Glu), an amino acid that can be present in the taste of wine as a result of the grapes used and the applied vinification techniques. Some techniques are likely to enhance the presence of Glu in wines, especially fermentation on yeast lees, a common procedure in the manufacture of many prestigious Chardonnay wines. During the malolactic fermentation, the relative content of Glu is also likely to increase. Sweet wines like Port and Madeira are also reported to have considerable amounts of Glu. In dairy fermentations, such as in cheese, there is sophisticated knowledge about the specific flavours and textures that are formed by different starter lactic acid bacteria. They provide desired enzymes which yield small peptides and free amino acids that give a certain cheese its specific character. As amino acids are also precursors of various volatile flavour compounds such as aldehydes and alcohols the development of specific wine yeasts that could impart specific desirable characteristics to a wine could prove to be an important venture in the production of successful wines.

Separation of L-aspartic acid and L-glutamic acid mixtures for use in the production of bio-based chemicals

BACKGROUND: Amino acids are promising feedstocks for the chemical industry due to their chemical functionality. They can be obtained by the hydrolysis of potentially inexpensive protein streams such as the byproduct of biofuel production. However, individual amino acids are required before they can be used for the further production of chemicals. Here, the separation of L-aspartic acid (Asp) and L-glutamic acid (Glu) mixture, which can be isolated from protein hydrolysis solutions at low pH or from electrodialysis of complex amino acid mixtures, was studied. RESULTS: Glu was converted into L-pyroglutamic acid (pGlu) which can be separated from the mixture of Asp and Glu due to its higher solubility in water. The conversion was carried out under aqueous or melt conditions. Under aqueous conditions, the conversion was studied as a factor of time, temperature and the amount of Glu. The conversion was specific with high yield and not effected by Asp. After pGlu was separated from Asp and residual Glu by solubility difference, it can be transferred back to Glu through hydrolysis. CONCLUSION: The conversion of Glu to pGlu is specific and can be applied to separation Asp and Glu for their use in the production of bio-based chemicals

Experimental study of the mechanism of seizure induction: changes in the concentrations of excitatory amino acids in the epileptic focus of the cat amygdaloid kindling model.

L-glutamate (Glu) and L-aspartate (Asp) are two major excitatory amino acids that may be involved in seizure susceptibility and seizure induction. The concentrations of Glu and Asp were measured by microdialysis in the epileptic focus in a cat amygdaloid kindling model. Sequential changes in Glu and Asp (before, during, and after seizure) were measured in the partial seizure (S4) and generalized seizure (S6) groups. By stimulation at and 50 microA below the partial seizure-triggering threshold in the S4 group and the generalized seizure-triggering threshold in the S6 group, Glu was released from the epileptic focus in the S4 group, and both Glu and Asp were released in the S6 group after seizure and stimulation (below threshold), and the amount of Glu and/or Asp release determined seizure induction. Excitatory amino acids may be the trigger of seizure induction in the cat amygdaloid kindling model.

Relation between long-lasting amounts of excitatory amino acid and its neuronal uptake system in cultured cerebellar granule cells under hypoglycemia

1. 1. Basal release of amino acids (Glu, Gln, Gly and Tau) in cultures of rat cerebellar granule cells was detected at 3 days in vitro (DIV). The amounts of Gln and Gly released increased according to days of culture. Moreover, the amounts of Glu in a glia poor culture of granule cells tended to be higher than those in glia rich cultured cells, while Gln, Gly and Tau concentrations were lower in glia poor cells than in glia rich cells. 2. 2. After depolarization induced by high KCl, amounts of all measured amino acids significantly rose to more than 1.5 times their basal values. The increase values obtained in a glia rich culture of granule cells were higher than those in a glia poor culture of cells throughout all cultured days. 3. 3. Under deprivation of glucose, most concentrations of amino acids in the medium, especially Gln concentration, increased by 50 mM KCl were lower than those seen under normal conditions. Such lesser efflux examined under hypoglycemia was much more clearly recognizaed in glia rich cultures than in glia poor cultures. However, the amounts of Glu at 10 and 14 DIV, and also Gly and Tau amounts at 10 DIV were significantly higher than those seen in the cultures of glia poor cells under normal conditions. 4. 4. The dosage of 10 μM Glu-induced [Ca 2+]i accumulation was inhibited by several different types of Ca antagonists and scopolamine. Meanwhile, the dosages of the tested drugs, except for scopolamine, required for blocking Glu-induced [Ca 2+]i accumulation under hypoglycemia were less than those required under normal conditions. These results suggest that neuronal death induced hypoglycemia might be caused by the dysfunction of the neuronal, but not glial, Glu uptake system, and that some Ca antagonists might be useful in preventing the neuronal death caused by hypoglycemia.

Differentiation of the photosynthetic apparatus of Chloroflexus aurantiacus depending on growth with different amino acids

The phototrophic green bacterium Chloroflexus aurantiacus was grown anaerobically in batch culture with different amino acids at 56°C and constant illumination of 25 klx. The composition of the photosynthetic apparatus was measured by quantitation of the bacteriochlorophylls (Bchl) a and c (representing the membrane-bound and the chlorosomal moieties, respectively). Ser added at concentrations up to 15 mM stimulated protein formation and Bchl a and c syntheses. A comparable stimulation was found with Glu and Ala. Coproporphyrin accumulation approached saturation at 5 mM of Ala, Asp, Orn, and Ser, while with Glu and Arg saturating concentrations were above 5 mM. Protein and tetrapyrrole syntheses became saturated at 2.5 to 5 mM of Asp, Ile, and Val. However, with Arg and Orn Bchl c synthesis was stimulated up to 2.5 mM, growth and Bchl a synthesis up to 5 mM. At higher Arg or Orn concentrations these activities were inhibited. Coproporphyrin accumulation was highest with Arg or Orn, at concentrations which inhibited growth and Bchl formation. Stimulation of Bchl synthesis took place preferentially at the level of Bchl c, while Bchl a was more sensitive toward inhibition. In both cases however, the ratio of Bchl c to Bchl a increased with higher amino acid concentrations. Nevertheless, each amino acid induced a typical effect. To understand different effects exerted by different amino acids, chemostat cultures were grown limited by either Ser or Glu. With Ser, steady state protein levels and specific Bchl a contents decreased slightly when increasing the dilution rate (D). Concomitantly Bchl c and coproporphyrin levels as well as the ratio of Bchl a/Bchl c increased. With Glu as the limiting substrate, all of the above mentioned parameters decreased. Since all of the Ser was consumed and increasing amounts of Glu remained unutilized in the spent medium, it is concluded that differences in the formation of the three pyrrole derivatives tested are due to differences in the affinities of uptake systems for Ser and Glu.

Use of the stable peptide, γ- l-glutamyl- l-tyrosine, as an intravenous source of tyrosine in mice

The relative insolubility of tyrosine (Tyr) at neutral pH limits amounts of this amino acid in solutions used for total parenteral nutrition (TPN). We have tested the potential of the natural peptide, γ- l-glutamyl- l-tyrosine (Glu(Tyr)), to release Tyr in vivo by making 20-μL injections, containing 2.9 μmol Glu(Tyr) (approximately 80 μmol/kg body weight), into the external jugular veins of mice. Mean concentrations of Glu(Tyr) in plasma were 138.5 and 11.4 μmol/L after 10 and 60 minutes, respectively; plasma Tyr was significantly elevated at 10 minutes, but returned to control levels at 60 minutes. When 5.8 μmol of Glu(Tyr) was injected, levels of Glu(Tyr) and of Tyr were significantly higher at both 10 and 60 minutes than when 2.9 μmol of peptide was injected. Animals showed no evidence of toxicity. Two percent or less of the peptide could be detected in the urine, even in mice injected with 5.8 μmol Glu(Tyr). Pretreatment of mice with acivicin, a potent inhibitor of γ-glutamyl transpeptidase (GGTase), prevented the increase in plasma Tyr seen after injection of 2.9 μmol Glu(Tyr) and led to higher levels of Glu(Tyr) in the plasma both at 10 and at 60 minutes than seen in mice given the same amount of Glu(Tyr) but no acivicin. The presence of the inhibitor also led to loss of as much as 48% of the administered peptide in the urine in 60 minutes. These data suggest that GGTase catalyzes hydrolysis of intravenous (IV) Glu(Tyr) to release Tyr in vivo. Glu(Tyr) in the blood is not partitioned into red blood cells; it remains in the plasma, available to GGTase, which functions at the external surface of cells. We suggest that this stable, soluble peptide may be useful in TPN as a means of normalizing the phenylalanine (Phe) to Tyr ratio in plasma and of providing sufficient Tyr to support optimal growth and development in low-birth-weight infants.

In vivo studies on the extracellular, and veratrine-releasable, pools of endogenous amino acids in the rat striatum: effects of corticostriatal deafferentation and kainic acid lesion.

The effects of corticostriatal deafferentation (decortication) and destruction of intrinsic neurons (intrastriatal kainate injection) on the extracellular concentration, and veratrine-releasable pools, of endogenous amino acids in the rat striatum were examined using the in vivo brain dialysis technique. Intracellular amino acid content was also determined. Decortication reduced selectively intra- and extracellular levels of glutamate (Glu) and aspartate (Asp). Extracellular changes were more pronounced than those in tissue content. gamma-Aminobutyric acid (GABA), taurine (Tau), and phosphoethanolamine (PEA) levels were not affected, whereas nonneuroactive amino acids were increased at 1 week but not at 1 month post-lesion. The intracellular pool of Glu and Asp was also reduced in kainate-lesioned striata. However, extracellular levels of these compounds were not affected significantly by this treatment. The tissue content of all other amino acids was decreased, the most prominent change being in the concentration of GABA. Extracellular GABA concentration was also reduced dramatically, whereas the concentrations of noneuroactive amino acids were increased to varying degrees. These data suggest that transmitter pools of neuroactive amino acids are an important supply for their extracellular pools. Lesion-induced alterations in nonneuroactive amino acids are discussed with regard to the loss of metabolic pools, glial reactivity, and changes in blood-brain barrier transport. Veratrine induced a massive release of neuroactive amino acids such as Glu, Asp, GABA, and Tau into the extracellular fluid, and a delayed increase in PEA. Extracellular levels of neuroactive amino acids were raised slightly. Decortication reduced, selectively, the amounts of Glu and Asp released by veratrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential Binding of Plasminogen to Crosslinked and Noncrosslinked Fibrins: Its Significance in Hemostatic Defect in Factor XIII Deficiency

Abstract In spontaneous fibrinolysis of an alpha 2-plasmin inhibitor-deficient plasma clot or tissue-type plasminogen activator-induced fibrinolysis in a purified system without alpha 2-plasmin inhibitor, the lysis was faster when factor XIII-mediated crosslinking of fibrin to fibrin did not occur. During the initial period, the binding of plasminogen to fibrin steadily increased with incubation time. The initial level and subsequent increase of the binding, which may be critical for the subsequent development of fibrinolysis, were more remarkable when fibrin was not crosslinked. The amount of glu- or lys-plasminogen bound to noncrosslinked fibrin was around 4 or 1.5 times larger than the amount of the respective plasminogen bound to crosslinked fibrin. Plasmin was also found to be bound to noncrosslinked fibrin twice as much as the amount bound to crosslinked fibrin. Structural changes induced by crosslinking of fibrin alpha-chain may reduce either the affinity or the number of available complementary sites to lysine binding sites of plasmin(ogen), thereby decreasing the binding of plasmin(ogen) to fibrin. These results suggest that an increased affinity of noncrosslinked fibrin for plasmin(ogen) is contributory to the accelerated fibrinolysis observed in factor XIII deficiency, in addition to an absence of crosslinking of alpha 2-plasmin inhibitor to fibrin.

Differential binding of plasminogen to crosslinked and noncrosslinked fibrins: its significance in hemostatic defect in factor XIII deficiency

In spontaneous fibrinolysis of an alpha 2-plasmin inhibitor-deficient plasma clot or tissue-type plasminogen activator-induced fibrinolysis in a purified system without alpha 2-plasmin inhibitor, the lysis was faster when factor XIII-mediated crosslinking of fibrin to fibrin did not occur. During the initial period, the binding of plasminogen to fibrin steadily increased with incubation time. The initial level and subsequent increase of the binding, which may be critical for the subsequent development of fibrinolysis, were more remarkable when fibrin was not crosslinked. The amount of glu- or lys-plasminogen bound to noncrosslinked fibrin was around 4 or 1.5 times larger than the amount of the respective plasminogen bound to crosslinked fibrin. Plasmin was also found to be bound to noncrosslinked fibrin twice as much as the amount bound to crosslinked fibrin. Structural changes induced by crosslinking of fibrin alpha-chain may reduce either the affinity or the number of available complementary sites to lysine binding sites of plasmin(ogen), thereby decreasing the binding of plasmin(ogen) to fibrin. These results suggest that an increased affinity of noncrosslinked fibrin for plasmin(ogen) is contributory to the accelerated fibrinolysis observed in factor XIII deficiency, in addition to an absence of crosslinking of alpha 2-plasmin inhibitor to fibrin.

Comparison of the 95,000 molecular weight protein from Limulus sperm with muscle alpha-actinin.

The 95,000 molecular weight protein (95K protein) of the false discharges of Limulus sperm, purified by means of preparative gel electrophoresis in the presence of sodium dodecyl sulfate, was compared with a 95K protein from Limulus muscle and chicken gizzard alpha-actinin. The results were as follows. 1) One-dimensional peptide mapping using four different proteases showed differences among these proteins. 2) Two-dimensional peptide mapping using trypsin showed that about 30% of the peptides in the digest of the sperm 95K protein were similar to those of chicken gizzard alpha-actinin and about 50% of the peptides were similar to those of the Limulus muscle 95K protein. 3) The sperm 95K protein contained relatively large amounts of Gly, Pro, and Ser and relatively small amounts of Glu and Leu compared to the muscle proteins. 4) Antibodies against the sperm 95K protein did not cross-react with the Limulus muscle 95K protein or chicken gizzard alpha-actinin. These results suggest that the 95K protein of sperm is different from alpha-actinin in primary structure.