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PubMed1992

[Effects of taurine and dipeptide Tyr-Tyr on ventricular defibrillation].

Results of the study of taurine and dipeptide Tyr-Tyr effect on the threshold values of functional lesions of the myocardium and heart defibrillation are reported. The experiments were carried out on 27 narcotized mongrel dogs weighing 12-30 kg. Defibrillation was performed using Lifepak-7 defibrillator (USA). Lesion threshold (LT), defibrillation threshold (DT) and electrotherapeutic index (ETI) as a LT:DT ratio were determined. In 14 experiments (control group) these parameters were evaluated during 3 h. In group 1 (6 experiments) taurine (100 mg/kg) was infused intravenously by the end of the 1st hour, in group 2--Tyr-Tyr (25 mg/kg). It was shown that infusion of taurine did not have a noticeable effect of the LT, DT and ETI values. Infusion of Tyr-Tyr resulted in an increase in LT and DT. The possibility to use dipeptide Tyr-Tyr in the complex of measures aimed at ceasing ventricular fibrillation is discussed.

Animals↗
PubMed1992

Antitumor effect of recombinant human tumor necrosis factor-alpha analog combined with desmuramyl dipeptides LK-409 or LK-410 on sarcoma in mice.

Antitumor effect of recombinant human tumor necrosis factor (TNF)-alpha lacking one to three amino acids from the N terminal part (TNFNv3) was tested for its antitumor effect on subcutaneous fibrosarcoma SA-1 tumors. Peritumoral treatment with 5 x 10(4) U TNFNv3 three times every second day significantly delayed tumor growth. Treatment with 10 times higher dose (5 x 10(5) U) produced 6.0 +/- 1.0 days tumor growth delay, but had side effects such as weight loss. The two new desmuramyl N-acyl dipeptides, LK-409 and LK-410, also exhibited such effect; however, the tumor growth delay was barely significant. The treatment was performed with two concentrations (2.5 micrograms and 25.0 micrograms) applied intraperitoneally for 5 consecutive days, without a dose-dependent effect. Combined treatment with TNFNv3 and desmuramyl dipeptides augmented the antitumor effect of treatments. The effect was additive and significant in the combination of 2.5 micrograms LK-410 with 5 x 10(5) U TNFNv3. LK-410 treatment also reduced the side effects of TNFNv3. The results indicate that combined treatment with both biological response modifiers is effective in tumor treatment.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMedDate not supplied

Capillary electrophoresis with a diamine EOF modifier as an approach for glutamine dipeptide containing formulations.

Currently, glutamine is thought to be conditionally indispensable amino acid. However, the use of glutamine in clinical practice encounters serious problems related to its limited solubility and instability in water solutions. Therefore, glutamine-containing dipeptides, which have better solubility and stability in the solution, have been introduced into the medical practice. High concentration of L-alanyl-L-glutamine in the medicinal product and thermal sterilization during the manufacturing process are the reasons of many impurities formation--the products of deamidation, racemization, cyclization etc.. The purpose of the study was to develop a single step CE method that could be applied in the purity control of L-alanyl-L-glutamine containing parenteral infusions instead of three routinely used LC methods. After systematic optimization separation conditions were selected: 100 mM borate buffer at pH 8.5 with 0.4 mM diaminopropane as EOF modifier. The method developed allows the separation and determination of the main component and the related impurities. The results show that the method is suitable for quality control of glutamine dipeptide solutions offering some advantages over routinely used LC methods.

Amino Acids, Diamino↗
PubMed2006

[Chiral separation of dipeptides by capillary electrophoresis].

Peptides are increasingly used as pharmaceutical agents. Many small peptides are the essential compounds in biological systems. Direct chiral separation of dipeptide derivatives using 9-(2-carbazole) ethyl chloroformate (CEOC) as the derivatizing agent by capillary electrophoresis (CE) with beta-cyclodextrin (beta-CD) and sodium deoxycholate (SDC) as chiral selectors has been developed. It has been well recognized that the combination of the binary selectors can enhance the selectivity and resolution instead of either beta-CD or SDC alone. The molar ratio of the binary chiral selectors, the buffer concentration and pH of Tris-H3PO4, organic modifier were studied and optimized. Complete chiral separations for 14 dipeptide derivatives using beta-CD and SDC as binary chiral selectors were obtained. The results indicated that each pair of D/L chiral resolution was more than 3.63, and the highest resolution for Gly-Ala was 43.14.

Calixarenes↗
PubMed2006

[The clinical efficacy of glutamine dipeptides on postoperative patients: an updated systematic review of randomized controlled trials from Europe and Asia (1997 - 2005)].

OBJECTIVE: To examine the effects of parenteral supplementation of glutamine dipeptide on the outcomes of surgical patients. METHODS: The relevant data 1997 to March or May 2005 were retrieved from SCI, Medline, EMBASE, Chinese Cochrane Centre databases. The bibliographies of the retrieved papers and the personal file were searched as well. All the patients in the retrieved papers received parenteral nutrition, whether alanyl-glutamine dipeptide (Ala-Gln) was added was the only difference between the intervention and control groups. Methodological quality assessment was based on the Cochrane Reviewers' Handbook and Jadad's Score Scale. Statistical software RevMan4.2 was used for meta-analysis. The data were treated by intention-to-treat method. RESULTS: A total of 1074 relevant papers were screened. Thirteen prospective randomized controlled clinical trials (RCTs) from European & Asian studies met the inclusion criteria. Ten RCTs reported 355 cases of infectious complications showed that Ala-Gln administration significantly reduced the prevalence of infectious complications with a pooled relative risk (RR) of 0.42 (95% CI 0.24 - 0.72; P = 0.002). Eight studies with 273 cases reported the postoperative length of stay (LOS) and showed that Ala-Gln significantly reduced the postoperative LOS by 3.25 days (95% CI = -4.87 to -1.62; P = 0.00009). There was no significant effect of Ala-Gln on cost of hospitalization, though there was a trend to reduction (2 studies, pooled n = 52, P = 0.2). CONCLUSION: Parenteral Ala-Gln significantly reduces the post-operative infectious morbidity and LOS among surgical patients.

Asia↗
PubMed2006

[The prospective study on application of parenteral nutrition with alanyl-glutamine dipeptide in chemotherapy of gastrointestinal neoplasms patients].

BACKGROUND & OBJECTIVE: There is an argument on whether or not glutamine-supplemented parenteral nutrition is beneficial to chemotherapy in gastrointestinal neoplasm patients. The aim of this study was to prospectively evaluate the effect of parenteral nutrition with alanyl-glutamine dipeptide on gastrointestinal neoplasm patients receiving chemotherapy. METHODS: This study was a prospective, randomized double-blind clinical trial. Seventy-two patients were randomly divided into study group and control group (each group had 36 patients). The side effects during chemotherapy were observed. Serum albumin, serum pre-albumin, IgG, IgA, IgM, C3, C4 level were measured before chemotherapy and on day 4 and day 8 after chemotherapy. Nitrogen balance was also calculated simultaneously. RESULTS: (1) Less side effects during chemotherapy in study group were revealed compared to those in control group (P<0.05). (2) Serum albumin and pre-albumin levels were both decreased in the two groups on day 4 after chemotherapy, and were markedly decreased in control group on day 8 after chemotherapy (P<0.05). (3) IgG, IgM, IgA levels were all decreased compared with the test results before chemotherapy on day 4 after chemotherapy in two groups, and were significantly decreased in control group on day 8 after chemotherapy (P<0.05). C3 and C4 levels were higher in study group compared with control group on day 8 after chemotherapy (P<0.05). (4) Nitrogen balance in study group was better than that in control group (P<0.05) on day 8 after chemotherapy. CONCLUSIONS: Alanyl-glutamine dipeptide is beneficial to chemotherapy in gastrointestinal neoplasm patients. It could reduce the side effects of chemotherapy, which helps to improve the nutritional status, the immune function and the survival quality of patients during chemotherapy.

Adult↗
PubMed1992

H+ coupled active transport of bestatin via the dipeptide transport system in rabbit intestinal brush-border membranes.

Bestatin [(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-leucine], a dipeptide containing an unusual amino acid, has been used clinically as an anticancer agent in p.o. dosage form. We examined the transport characteristics of [3H]bestatin by rabbit intestinal brush-border membrane vesicles. Bestatin uptake was stimulated by an inward H+ gradient (overshoot phenomenon) and by an interior-negative membrane potential. About half of the apparent bestatin uptake at 1 mM by brush-border membrane vesicles was estimated as binding to the membranes. The affinity constant for the bestatin transport was 0.52 mM. The uptake of bestatin by brush-border membrane vesicles was inhibited by p.o. cephalosporins and dipeptides, but not by amino acids. In vesicles preloaded with either bestatin, cephradine or glycylsarcosine, the uptake of [3H]bestatin was stimulated markedly (countertransport effect). These results indicate that bestatin is transported via the H+/dipeptide transport system in rabbit intestinal brush-border membranes.

Aminopeptidases↗
PubMed1991

Kinetically controlled synthesis of dipeptides using ficin as biocatalyst.

The application of the sulfhydryl protease ficin as biocatalyst is proposed as a novel method for enzyme-catalyzed synthesis of dipeptides. The negligible peptidase but considerable esterase activity at alkaline pH facilitated the kinetically controlled formation of peptide bonds by coupling the ester substrates Z-Ala-OMe and Z-Gly-OMe with L-alanine, D-alanine, L-glutamine, D-glutamine and L-Cys(acetamidomethyl) respectively. The reaction is accomplished without the occurrence of secondary peptide hydrolysis. Under optimum reaction conditions (pH 9.2, high ratio nucleophile/carboxyl component, 4.8% ethanol, 40 degrees C), the peptide yields ranged from 5 to 91%, depending on the structure of the amino and/or carboxyl component. No racemization was observed in the enzymatic reaction. Application of short-chain peptides has been advocated recently in clinical nutrition. Ficin-catalyzed peptide synthesis might be an attractive biotechnological approach for the synthesis of suitable dipeptides in this respect.

Amino Acids↗
PubMed1991

[Ileal absorption of various amino acids and dipeptides in rats administered cyclophosphamide--using the short-circuit current method].

Transport of amino acids; glycine, L-alanine, L-leucine, L-proline, L-lysine and dipeptides; gly-gly, gly-L-pro, gly-L-leu, L-leu-gly was investigated by measuring the short-circuit current in control rats and the rats 3 days after intraperitoneal injection of cyclophosphamide (CPM) 300 mg/kg. For determining active transport using the short-circuit current method in injured intestinal epithelia the short-circuit current measured should be corrected for the decrease in the mucosal resistance of CPM group. Jmax values for transport of glycine and L-alanine in ileum are significantly decreased in CPM group than in control group. Contrariwise, there are no differences in Jmax values for peptides transport in ileum between two groups. The results indicate that the glycine transport carrier is more sensitive to CPM injury than the peptide transport carrier for glycine-containing dipeptide, suggesting the clinical usefulness of the peptide nutrition during chemotherapy.

Amino Acids↗
PubMed1991

Synthesis of amino-acid derivatives and dipeptides with an original peptidase enzyme.

A peptidase from the non pathogenic Staphylococcus sp. strain BEC 299 was purified to a final specific activity of 84,400 U/mg protein. Its molecular weight is 450 kDa and optimum pH 10.0. This enzyme catalyzes the synthesis of dipeptides (aspartame) and alpha-amino acid derivatives (N-L-malyl-L-tyrosine ethyl ester). The influence of cosolvents and pH on dipeptides and alpha-amino acid derivative synthesis is described. Finally, we detail the use of the peptidase as a reagent in protease-catalyzed peptide synthesis.

Amino Acids↗
PubMedDate not supplied

[Thermodynamic and spectroscopic study of intermolecular association in aqueous dipeptide solutions].

Peculiarities of the concentration dependences of apparent molar heat capacities and volumes of aqueous solutions of dipeptides were considered. Possible interpretation of the character of these dependences on the basis of Gibson and Sheraga's model of solvation shell were shown. Three concentration regions corresponding to the existence of various molecular forms of dipeptides in solution were marked out.

Dipeptides↗
PubMed1990

Metabolism of dipeptides by isolated and perfused nonfiltering kidneys.

Renal metabolism of Glycyl-glycine (Gly-gly), Glycyl-proline (Gly-pro) and Prolyl-glycine (Pro-gly) was studied in the non-filtering, isolated perfused rat kidney. Gly-gly is metabolized by more than 90% after 120 min of perfusion. Gly-pro is more resistant to degradation and about 75% of the original peptide can be found intact in the perfusate at the end of perfusion. For Pro-gly, only 25% remains intact at the end of the experiment. Glycine was also monitored as another marker for dipeptide degradation and its production increased throughout the perfusion time. In some experiments we also determined the production of proline. We conclude from these experiments that the basolateral membrane, or perhaps the kidney blood vessels, possess an efficient apparatus for the hydrolysis of Gly-gly and Pro-gly. This mechanism is less efficient in the case of Gly-pro. This confirms an earlier hypothesis that dipeptide metabolism does not occur solely in the brush-border membranes.

Animals↗
PubMed1990

Metal-tetracycline/H+ antiporter of Escherichia coli encoded by a transposon, Tn10. The role of the conserved dipeptide, Ser65-Asp66, in tetracycline transport.

The transposon Tn10-encoded tetracycline resistance protein functions as a metal-tetracycline/H+ antiporter (Yamaguchi, A., Udagawa, T., and Sawai, T. (1990) J. Biol. Chem. 265, 4809-4813). The Ser65-Asp66 dipeptide is conserved in all known tetracycline antiporter proteins and is an important target for site-directed mutagenesis. When Asp66 was replaced by Asn, the transport activity was completely lost, whereas when it was replaced by Glu, the activity was reduced to 10% of the wild-type level, indicating that a negative charge at position 66 is essential for tetracycline transport. Replacement of Ser65 by Cys or Ala, in contrast, caused only a minor change in tetracycline transport activity. However, the Cys65 mutant antiporter was sensitive to sulfhydryl reagents. Complete inactivation of the Cys65 antiporter by N-ethylmaleimide was not prevented by the substrate. A less bulky reagent, methyl methanethiosulfonate, caused partial inactivation of the Cys65 antiporter without changing its affinity to the substrate. These results indicate that a region including the dipeptide plays an important role in metal-tetracycline transport except for substrate binding. It may act as a gate which opens on the charge-charge interaction between Asp66 and the metal-tetracycline.

Amino Acid Sequence↗
PubMed1989

Glutamine-containing dipeptides as infusion substrates in the septic state.

Recently a relationship has been postulated between lowered intracellular glutamine concentrations in the skeletal muscle and the rate of protein synthesis. We investigated the effect of 48 hours of parenteral nutrition supplemented with a solution containing glutamine in free or dipeptide form (alanylglutamine or glycylglutamine) on the intracellular glutamine pool in skeletal muscle and on the hind limb exchange of glutamine in dogs with sepsis after surgery. Before surgery, dogs were fasted for 48 hours. We used glutamine dipeptides as sources because they remain stable in an aqueous solution. Nutrition solutions were isocaloric (17.8 kcal/kg body weight/day on day 1 and 35.6 kcal/kg on day 2) and isonitrogenous (0.33 gm nitrogen/kg body weight/day), providing 2.6 mmol/kg body weight/day as glutamine source. During starvation, muscular free glutamine levels decreased by 41% to 10.4 mmol/L (p less than 0.001). On the second postoperative day the dogs had lowered plasma protein levels, a sharp drop in platelet count, an increase in the leukocyte count, and positive blood cultures. None of the solutions investigated in this study was effective in repleting the glutamine pool during 2 days of postoperative nutrition (11 +/- 2.0 mmol/L without glutamine, 10.3 +/- 2.2 mmol/L with glutamine plus alanine, 9.9 +/- 1.6 mmol/L with alanylglutamine, 7.5 +/- 1.1 mmol/L with glutamine plus glycine, and 7.2 +/- 1.2 mmol/L with glycylglutamine, respectively). The release of glutamine from the hindquarter was 631 +/- 38 nmol/kg body weight/min in the control group and decreased significantly in dogs receiving alanylglutamine (13.5 +/- 45 nmol/kg body weight/min; p less than 0.001) or the constituent amino acids (265 +/- 66 nmol/kg body weight/min; p less than 0.01) but was unchanged in dogs receiving glycylglutamine or glutamine plus glycine. We conclude that the duration and dosage of glutamine administration (equivalent to 26 gm glutamine per day in a patient weighing 70 kg) used in this study are not sufficient to restore glutamine deficiency of the skeletal muscle in the depleted state.

Alanine↗
PubMedDate not supplied

[Various features of the initial stages of assimilation of isotope-labelled dipeptide].

Tritium-labeled dipeptide Gly-Leu was administered to noninbred guinea pigs by intracardiac injections, and to Wistar rats--intra-intestinally, through a specially implanted catheter. It was found that after intravenous and intraintestinal administration of isotope-labeled dipeptide the "low-molecular label" was bound by serum proteins. Dissociation of the complexes "low-molecular label"--serum protein in 8 M solution of urea has evidenced a predominantly reversible character of interaction between the low-molecular ligand and protein macromolecule. The results obtained should be taken into consideration during assay of protein absorption from gastro-intestinal tract of laboratory animals.

Animals↗
PubMed1985

Dipeptides of glutamate and aspartate may be endogenous neuroexcitants in the rat hippocampal slice.

The dipeptide N-acetylaspartylglutamate (NAAG), and possibly the related dipeptide aspartylglutamate (AG), have been found in high concentrations in rat brain, and have been shown to bind avidly and selectively to a subset of glutamate (GLUT) receptors. Certain observations regarding GLUT and aspartate might be explained if the endogenous transmitter were a compound composed of both amino acids. We therefore examined the electrophysiological actions of NAAG and AG in the rat in vitro rat hippocampal slice model. NAAG or AG and GLUT were applied locally to cells by a dual-barrel pressure technique. Intracellular recordings from 34 CA1 pyramidal neurons showed depolarizations and conductance increases resembling evoked excitatory postsynaptic potential in 15 of 20 cells exposed to NAAG, and 14 of 14 exposed to AG. Many GLUT-responsive sites did not respond to AG, and most did not respond to NAAG. Responses to NAAG were usually too small to induce cell firing; they were best detected, therefore, by intracellular recording. With extracellular unit recordings, GLUT was equally excitatory in stratum radiatum and pyramidale of CA1 (N = 19; p greater than 0.10, one-way analysis of variance). In contrast, AG was considerably more potent (N = 21; p less than 0.01) in stratum radiatum. NAAG was not noted to excite cells when applied to stratum pyramidale. The region of maximal responsiveness to AG in CA1 coincided with the area of the dendritic tree receiving Schaffer collateral-commissural afferents. This spatial profile, together with other neuropharmacological evidence, support the candidacy of glutamate-containing peptides as endogenous excitatory compounds in certain pathways of hippocampus.

Animals↗
PubMed1986

H+ coupled uphill transport of aminocephalosporins via the dipeptide transport system in rabbit intestinal brush-border membranes.

The transport characteristics of aminocephalosporin antibiotics, possessing an alpha-amino group and a carboxyl group, in brush-border membranes isolated from rabbit small intestine have been studied by a rapid filtration technique. The uptake of cephradine by brush-border membrane vesicles was stimulated by the countertransport effect of dipeptides, which indicates the existence of a common carrier transport system. An inward H+ gradient ([pH]i = 7.5 to 8.4, [pH]o = 6.0) stimulated cephradine uptake against a concentration gradient (overshoot phenomenon), and this stimulation was reduced when the H+ gradient was subjected to rapid dissipation by the presence of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, a protonophore. A valinomycin-induced K+ diffusion potential (interior-negative) stimulated H+ gradient-dependent cephradine uptake without altering the equilibrium value. The uptake of other aminocephalosporins (cefadroxil, cefaclor, cephalexin) was also stimulated in the presence of an inward H+ gradient, while the uptake of cephalosporins without the alpha-amino group (cefazolin, cefotiam) was not changed in the presence or absence of the H+ gradient. These results suggest that the transport of aminocephalosporins can be driven actively by an inward H+ gradient via the dipeptide transport system in the intestinal brush-border membranes, and that the process results in the transfer of a positive charge.

Animals↗
PubMed1988

Spatial working memory in rats: the effect of the dipeptide gamma-L-glutamyl-taurine and haloperidol.

To assess the possible involvement of the dipeptide gamma-L-glutamyl-taurine (Litoralon) and some of its analogues in the maintenance of spatial working memory, rats were treated with the dipeptides immediately or 2 hours after completing the first four choices in an 8 arm radial maze, or 3 hours before the test to exclude proactive effects of the compounds. Treatment with Litoralon, SZJ 3381 and 3361 at doses of 100 and 500 micrograms/kg (i.p.) did not impair spatial memory in rats, regardless of when these substances were injected during the session. By contrast, haloperidol (500 micrograms/kg, i.p.) treatment resulted in a dramatic decrease of performance.

Animals↗