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PubMed1990

[Effect of some GABA, glycine, or glutamic acid derivatives on the forced swimming test in mice].

Three GABA derivatives, the GABA-steatamide (GS), the GABA-linoleamide (GL) and the progabide, two glycine derivatives, the glycine-steatamide (SG) and the glycine-linoleamide (LG) and, lastly, a glutamic acid derivative, the glutamic acid palmitamide (PGt), were studied in the forced swimming test (Porsolt's test) on mice. The anti-immobility effect, referring to the existence of antidepressive properties, was significant for the SG, LG, GL and PGt. It seems that the relative intensity of the anti-immobility effect on the one hand and the sedative properties on the other, could operate on the experimental profile of these derivatives in the Porsolt's test.

Animals↗
PubMedDate not supplied

Noninvasive visualization of in vivo drug delivery of poly(L-glutamic acid) using contrast-enhanced MRI.

Biomedical imaging is valuable for noninvasive investigation of in vivo drug delivery with polymer conjugates. It can provide real-time information on pharmacokinetics, biodistribution, and drug delivery efficiency of the conjugates. Noninvasive visualization of in vivo drug delivery of polymer conjugates with contrast-enhanced magnetic resonance imaging (MRI) was studied with paramagnetically labeled poly(L-glutamic acid) in an animal tumor model. Poly(L-glutamic acid) is a biocompatible and biodegradable drug carrier for diagnostics and therapeutics. Poly(L-glutamic acid)-1,6-hexanediamine--(Gd-DO3A) conjugates with molecular weights of 87, 50, and 28 kDa and narrow molecular weight distributions were prepared and studied in mice bearing MDA-MB-231 human breast cancer xenografts. Contrast-enhanced MRI resulted in real-time and three-dimensional visualization of blood circulation, pharmacokinetics, biodistribution, and tumor accumulation of the conjugates, and the size effect on these pharmaceutics properties. The conjugate of 28 kDa rapidly cleared from the circulation and had a relatively lower tumor accumulation. The conjugates with higher molecular weights exhibited a more prolonged blood circulation and higher tumor accumulation. The difference between the conjugates of 87 and 50 kDa was not significant. Contrast-enhanced MRI is effective for noninvasive real-time visualization of in vivo drug delivery of paramagnetically labeled polymer conjugates.

Animals↗
PubMed1986

Membrane potential dependency of glutamic acid transport in rabbit jejunal brush-border membrane vesicles: K+ and H+ effects.

We have applied our recently developed approach for quantitative generation and estimation of membrane potential differences (Berteloot, A. (1986) Biochim. Biophys. Acta 857, 180-188) to the reevaluation of glutamic acid transport rheogenicity in rabbit jejunal brush-border membrane vesicles. Membrane diffusion-potentials were created by altering iodide concentrations in the intra- and extravesicular compartments while keeping isosmolarity, isotonicity and ionic strength constant by chloride replacement. The known value of ion permeabilities relative to sodium in this preparation also allows calculation of membrane potential differences using the Goldman-Hodgkin-Katz equation. This strategy appears superior to more classical methods involving ionophore-induced membrane diffusion-potentials of protons or potassium as both cations have been shown to participate in the transport mechanism. In this paper, we demonstrate that this approach is perfectly suitable for the investigation of membrane potential dependency of glutamic acid transport as our results showed that chloride replacement by iodide did not affect uptake in vesicles with membrane potential clamped to zero by gramicidin D (sodium conditions) or by gramicidin D plus valimonycin (sodium + potassium conditions). The method thus allows to dissociate membrane potential effects from possible effects that might be introduced by altering the anion species. In these conditions, our studies clearly demonstrate that glutamic acid uptake, whether analyzed over a 1 min time scale or under initial rate conditions, was sensitive to membrane potential differences. However, our results also show that the electrogenicity of the transport system varied depending upon the intravesicular presence or absence of potassium, its presence stimulating the membrane potential dependency of uptake. This effect is modulated by the internal pH and it is concluded that inside H+ and K+ are not equivalent as countertransported cations. The external pH also seems to modulate the response to potential by acting on the fully loaded form(s) of the transporter. The possibility that outside H+ competes for (an) external Na+ binding site(s) and/or precludes the attachment of (an) extra sodium ion(s) should be considered.

Animals↗
PubMed2002

Fourier transform IR study of aggregational behavior of N-acetyl-L- and N-butyloxycarbonyl-L-glutamic acid oligomeric benzyl esters in dioxane and benzene: beta-turn --> antiparallel beta-sheet transition.

Oligomeric N-acetyl-L-glutamic acid benzyl esters (AN(p)Z) with exact residue numbers (N(p) = 2, 3, 4, and 5) and N-butyloxycarbonyl-L-glutamic acid benzyl esters (BOCN(p)Z) with exact residue numbers (N(p) = 4, 5, 6, and 8) are synthesized by a stepwise procedure in a liquid phase. The aggregational behavior of these oligomeric molecules in dioxane and benzene is examined by Fourier transform IR spectra. In particular, the concentration dependence of the IR spectra for the AN(p)Z solutions with N(p) values of 4 (A4Z) and 5 (A5Z) shows that the predominant antiparallel beta-sheet structure is stabilized above the critical aggregation concentration (cac), while other conformations including beta-turns may coexist below the cac. This fact provides evidence that aggregation induces the conformational transition from other conformers (probably beta-turns) to an antiparallel beta-sheet form. The IR results for the A3Z and A2Z solutions indicate that specific conformers (beta-turns), which are different from the beta-sheet structure, may be preferentially stabilized upon aggregation. Thus, the critical residue number of the AN(p)Z oligopeptides, which is essential for formation of a rodlike aggregate in dioxane and benzene, is 4 or 5.

Amino Acid Sequence↗
PubMed1981

A modified, high yield procedure for the synthesis of unlabeled and 14C-labeled 4-methylene-DL-glutamic acid.

This paper describes the complete chemical synthesis of 4-methylene-DL-glutamic acid from diethylmalonate, formaldehyde and diethyl acetamidomalonate. The amino acid was obtained pure following ion-exchange chromatography and/or crystallization from hot water in an overall yield of 30% based on the amount of diethylmalonate used. Several physico-chemical characteristics of the synthetic compound were determined, including ir and pmr spectra, chromatography on paper, retention time on an amino acid analyzer, pK values and melting point; all properties of the synthetic material were found to be identical to those seen with the naturally occurring L-isomer. The procedure for obtaining gram quantities of the unlabeled compound has also been modified for the synthesis of high specific activity (10.6 mCi/mol) 4-methylene-[2-14C]-DL-glutamic acid.

Chromatography, Ion Exchange↗
PubMedDate not supplied

Azobenzene-modified poly(l-glutamic acid) (AZOPLGA): its conformational and photodynamic properties.

Azobenzene-modified poly(l-glutamic acid) (AZOPLGA) polymers with 22 and 35 mol % of azo chromophores in the side chains have been synthesized by condensing 4-methoxy-4'-aminoazobenzene and poly(l-glutamic acid). These polymers have been characterized by NMR, FT-IR, and UV-visible spectroscopic techniques. The conformational features of the polymer backbone chains in the films that were cast from the polymer solutions prepared in different solvents have been investigated by circular dichroism spectroscopy. Experimental data suggested that the thermal cis-trans relaxation and photoinduced birefringence, which are related to the azo chromophores in the side chains of polymer, are not affected by the conformations of polymer backbones. However, the modulations of the surface relief gratings, the result of photoinduced mass transport process, recorded on these polymers are sensitive to polymer main chain conformation, as well as the degree of functionalization.

Azo Compounds↗
PubMed1990

[The synergistic action of glutamic acid and phosphocreatine on the metabolism and function of the heart during ischemia and reperfusion].

The combined effect of glutamic acid (15 mM) and phosphocreatine (10 mM) on metabolism and postischemic recovery of cardiac function was studied in isolated perfused working guinea pig hearts. Addition of these two agents into standard hyperpotassium cardioplegic solution increased twice the recovery of the aortic output and improved restoration of volume work and an index of functional recovery. This effect was combined with the complete recovery of ATP, phosphocreatine, the decrease in ammonia and lactate tissue contents and preservation of amino acid pool. Lesser leakage of creatine and creatine kinase pointed to lesser damage of the sarcolemma. The results show the effectiveness of the use of cardioplegic solution containing both glutamic acid and phosphocreatine.

Animals↗
PubMed1982

The varying tissue distribution of L-glutamic acid labelled at three different sites.

Methods using 5 and 6 enzymes were devised to synthesize L-[11C]glutamic acid (GA), labeled on the carboxyl group of either the alpha-(AGA) or gamma-(GGA) carbon atom. The distribution of the 11C-labeled AGA or GGA in rabbits was compared with that of L-[13N]glutamic acid. The results show that AGA was rapidly decarboxylated with loss of the 11C-label, and that GGA was also decarboxylated, but to a lesser degree. Thus, the radiolabel distribution may not reflect the distribution of the original compound. The results also demonstrate that positron labeled pharamaceuticals may be rapidly synthesized via complex enzymatic pathways.

Animals↗
PubMed1992

[Functionally important residues of glutamic acid in E. coli pyrophosphatase. I. Chemical modification and localization in the primary structure].

Inorganic pyrophosphatase of E. coli is rapidly and irreversibly inactivated by 5-ethyl-5-phenylisoxazolium-3'-sulfonate (Woodward's reagent K). The appearance in the absorption spectrum of a maximum at 340 nm testifies to the formation of an enzyme enol ester with the inhibitor. The non-hydrolyzable substrate analog CaPP1 partly protects the enzyme from inactivation. A peptide has been isolated from a tryptic hydrolysate of inactivated enzyme which contains an amino acid residue whose modification is critical for the enzyme activity. This peptide corresponds to residues 95-104 of pyrophosphatase and contains four dicarboxylic acid residues. A peptide containing a modified glutamic acid residue was isolated from modified pyrophosphatase hydrolyzed by protease v8. This peptide represents a fragment of a tryptic modified peptide and has a Glu-Ala-Gly-Glu (residues 98-1C1) structure. It is concluded that inactivation of E. coli pyrophosphatase by Woodward's reagent K is a result of selective modification of Glu98, apparently by the most reactive dicarboxylic amino acid within the enzyme active center.

Amino Acid Sequence↗
PubMed1987

[Analysis of the effect of glutamic acid diethyl ester on synaptic processes in the ampullae of Lorenzini of the skate].

The effects of glutamic acid diethylester (GDEE) on the electrical activity of the ampullae of Lorenzini were studied in skates. GDEE (10(-6)-10(-4) M) caused a decrease in frequency of afferent discharges in all receptors under study. GDEE also reversibly blocked the effects of excitatory amino acids (L-glutamate and L-aspartate). The results suggest that L-glutamate or related substance is likely to be the synaptic transmitter in the ampullae of Lorenzini.

Animals↗
PubMed1976

Incorporation of glutamic acid into soluble protein as a function of age.

The incorporation of U-14C glutamic acid into soluble bovine and human lens protein fractions has been studied as a function of age. Culture technique and DEAE cellulose fractionation has been used. In bovine lenses the incorporation of glutamic acid into alpha and gamma crystallins decreased with age whereas in the beta crystallin group the specific activities remained constant. All protein fractions of the human lenses showed a gradual reduction of the incorporation of the radioactive amino acid between 40 and 74 years of age. The highest specific activity was found to correspond to Spector's HL protein and its existence is confirmed throughout the whole human life-span.

Aging↗
PubMed1997

[Interaction of L-glutamic acid with human T-lymphocytes].

A specific interaction of [3H]Glu with T lymphocytes from the blood of healthy donors (Kd = 0.236 microM) was revealed and described. It was found that unlabeled quisqualate, a structural analogue of L-glutamic acid, and unlabeled dipeptides Ala-Glu, Glu-Ala, and Glu-Glu competitively inhibit the specific binding of [3H]Glu to T lymphocytes (with Ki 0.19, 2.4, 3.4, and 1.2 microM, respectively). Binding experiments with conjugates of labeled and unlabeled glutamic acid with dextran showed that the receptors of [3H]Glu are localized on the outer surface of the plasma membrane of T lymphocytes.

Binding, Competitive↗
PubMed2007

Novel syntheses of chiral beta- and gamma-amino acid derivatives utilizing N-protected (aminoacyl)benzotriazoles from aspartic and glutamic acids.

Friedel-Crafts reactions of N-protected (alpha-aminoacyl)benzotriazoles with hetero- and benzenoid- aromatics give alpha-amino ketones that can be reduced by either triethyl silane or sodium borohydride to form the corresponding beta- and gamma-amino acid derivatives. The preservation of chirality throughout this process is confirmed by chiral HPLC results.

Amino Acids↗
PubMed1997

[Preparation of leucine-methyl glutamate-glutamic acid copolymers].

The method for preparing leucine-methyl glutamate-glutamic acid copolymer was studied. In the first place benzyl glutamate and methyl glutamate were synthesized respectively. Then N-carboxy anhydrides (NCA) of leucine, benzyl glutamate or methyl glutamate were prepared in a closed container by phosgene-toluene solution method. After copolymerization the copolymers were debenzylated and demethylated by anhydrous hydrogen bromide. The free carboxyl group mole content in side chains of the copolymer was controlled by various standing periods following bubbling HBr. Analysis of infrared spectrogram and ultraviolet asorbance of copolymers indicated that this procedure resulted in the loss of almost all benzyl groups and some methyl groups.

Glutamic Acid↗
PubMed1983

Gamma-aminobutyric acid interneurons in the rat hippocampal region studied by retrograde transport of glutamic acid decarboxylase antibody after in vivo injections.

The retrograde axonal labeling of hippocampal GABA-ergic neurons was studied after in vivo injections of a characterized antibody against glutamic acid decarboxylase (GAD) into different parts of the hippocampal region. Small injections (50 nl) of undiluted GAD antibody into the area dentata (AD) labelled fusiform and dentate pyramidal basket cells within the AD and fusiform and multipolar cells in subfields CA2/CA3 (a and b) of Ammon's horn. The labeled cells were characterized by intense immunoreactivity of the soma and proximal parts of the dendrites, while the nucleus contained little or none. The morphological appearance and laminar positions of these cells corresponded to hippocampal GAD-positive neurons, as shown previously (Ribak et al. 1978) with immunocytochemistry. Injections of anti-GAD into the medial entorhinal area, subiculum, and CA1 region labeled cells in strata oriens, pyramidale and radiatum of CA2 and CA3a, but injections of the antibody into these latter areas failed to label cells in the medial CA1 and subiculum, thus suggesting a preferential organization of hippocampal GABA neuronal projections in a lateral to medial direction. Injections of preimmune sera or antiserum preabsorbed with the pure enzyme antigen GAD failed to label cells in a manner similar to that described for the anti-GAD injections. These observations, taken together with the finding that injections of anti-GAD into the terminal field of non-GABA-ergic pathways never resulted in retrograde axonal transport of the antibody-antigen complex, suggest that the in vivo injection of GAD antibody is a useful method to study the organization of hippocampal GABA-ergic neurons and their projections.

Animals↗
PubMed2000

Biodistribution of paclitaxel and poly(L-glutamic acid)-paclitaxel conjugate in mice with ovarian OCa-1 tumor.

PURPOSE: Poly(L-glutamic acid)-paclitaxel (PG-TXL) is a water-soluble paclitaxel (TXL) conjugate made by conjugating TXL to poly(L-glutamic acid) via ester bonds. In preclinical studies, PG-TXL has shown significant antitumor activity against a variety of solid tumors. To elucidate the relationship between tissue distribution and antitumor efficacy of PG-TXL, we studied and compared the biodistribution of PG-TXL and TXL. METHODS: Female C3Hf/Kam mice bearing syngeneic ovarian OCa-1 tumors were injected with either [3H]TXL or PG-[3H]TXL at an equivalent TXL dose of 20 mg/kg. Mice were killed at various times after drug injection, and samples of blood, spleen, liver, kidney, lung, heart, muscle, brain, fat, and tumor were removed and the radioactivity counted. In addition, concentrations of free [3H]TXL released from PG-[3H]TXL in the spleen, liver, kidney, and tumor were analyzed by using high-performance liquid chromatography (HPLC). Whole-body autoradiographs of mice killed 1 day and 6 days after administration of PG-[3H]TXL were obtained to study the intratumoral distribution of PG-TXL. RESULTS: When [3H]TXL was conjugated to polymer, the biodistribution pattern of PG-[3H]TXL differed from that of [3H]TXL. Based on area under the tissue concentration-time curve (AUC) values, tumor exposure to [3H]TXL was five times greater when administered as PG-TXL than as TXL formulated in Cremophor EL/alcohol vehicle. Furthermore, concentrations of free paclitaxel released from PG-[3H]TXL remained relatively constant in tumor tissue, being 489, 949 and 552 ng/g tumor tissue at 5, 48 and 144 h after dosing, respectively. Autoradiographic images of mice injected with PG-[3H]TXL revealed that radioactivity was primarily located in the periphery of the tumor on day 1 after drug administration and was homogeneously diffused into the center of the tumor by day 6. Over the 144-h study period, [3H]TXL concentrations, predominantly as the inactive conjugate, were higher in tissues with a more abundant reticular endothelial system (i.e. liver, kidney, spleen, lung) than in tissues with less abundant or lacking RE systems (i.e. muscle, fat, brain). Both [3H]TXL and PG-[3H]TXL were excreted primarily through the hepatobiliary route, with a small fraction of each drug (5% and 8.7%, respectively) excreted into the urine within 48 h. CONCLUSIONS: This study indicates that the distribution to tumor tissue was enhanced when [3H]TXL was administered as a macromolecular conjugate, and that free TXL was released and maintained within the tumor for a prolonged period. Thus, the antitumor activity of PG-TXL observed in preclinical studies may be attributed in part to enhanced tumor uptake of PG-TXL.

Animals↗
PubMed1991

Adaptation of an enzymatic fluorescence assay for L-glutamic acid decarboxylase.

The activity of L-glutamic acid decarboxylase (GAD) is commonly estimated by several radiometric methods, whereas a fluorimetric assay based on an enzymatic formation of NADPH as described by Y. Okada and C. Shimada [(1975) Brain Res. 98, 202-206] has been given little attention in biochemical and pharmacological investigations. A simple modification of this assay is presented to permit rapid and sensitive GAD measurements in unpurified tissue homogenates. This method, employing a linear NADPH standard curve, is demonstrated to be a valid assay system for a pharmacological approach using 3-mercaptopropionic acid.

3-Mercaptopropionic Acid↗
PubMed1995

Hippocampal granule cells express glutamic acid decarboxylase-67 after limbic seizures in the rat.

Temporal lobe epilepsy is the most common form of epilepsy. Decreased GABA-ergic inhibition has been suggested as one cause of hyperexcitability. On the other hand, increased expression of glutamic acid decarboxylase, the rate-limiting enzyme of GABA synthesis, has been found in interneurons of the hippocampus in patients with temporal lobe epilepsy and in rats after kainic acid-induced limbic seizures, indicating increased GABA-ergic transmission. Here we report differential expression of two genes encoding different molecular forms of glutamic acid decarboxylase (GAD), GAD65 and GAD67, after kainic acid-induced seizures in the rat. There is a rapid but transient elevation of GAD67 mRNA levels in granule cells 6-24 h after kainic acid injection, followed by enhanced GAD immunoreactivity in the terminal field of mossy fibers. In interneurons in the hilus of the dentate gyrus, a sustained and progressing increase in the expression of both GAD65 and GAD67 messenger RNA occurs. These observations indicate that consitutively glutamatergic mossy fibers may be capable of synthetizing and utilizing the inhibitory transmitter GABA in sustained limbic seizures. Enhanced expression of glutamic acid decarboxylases within interneurons and in granule cells/mossy fibers suggest augmented GABA-ergic neurotransmission supporting selfprotective, anticonvulsive mechanisms in limbic epilepsy.

Animals↗