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At least 397 records · Page 22Linked to original sources
PubMed1999

[Effect of the NMDA receptor antagonist on parameters of delayed visual differentiation and rearrangement of the impulse activity of neurons in visual and prefrontal cortices in monkeys].

With the aid of a multichannel leads the unit activity was recorded in the 17th and 8th cortical fields along with registering behavioural data in Rhesus monkeys. Multi-factor variance analysis revealed that the 2-amino-5-phospho-valeric acid (APV) effect involved a significant worsening of the monkeys' behavioural characteristics: duration of the short-term memory shortened (2-4-fold), motor reactions' time increased, and the changes of cognitive characteristics were always followed by significant rearrangements of the unit activity in the above areas. The data obtained suggest that these cognitive dysfunctions are due to a desynchronisation of unit activity in different areas of the cortex including the neuronal assemblies maintaining the short-term memory mechanisms associated with the glutamatergic structures.

Animals↗
PubMed1975

The inhibition of macrophage migration inhibtory factor (38485).

Analogs of EACA were capable of inhibiting the in vitro activity of macrophage migration inhibitory factor (MIF). The most active analog of EACA in terms of MIF inhibition had four methyl groups separating an acetylated amino group from a free carboxyl group. This compound, acetylated 5-amino valeric acid, was capable of inhibiting completely MIF activity in vitro at a concentration of less than 10-6 M without demonstrating any appreciable antitryptic activity, even at 10-3 M. Antitryptically active EACA did not inhibit MIF except at very high concentrations (10-2M). Further, the most purified preparations of MIF obtained from aqueous extracts of thymus that we have studied contained no significant proteolytic activity upon denatured hemoglobin at pH 3-8. Therefore, we do not correlate anti-tryptic with anti-MIF activity in vitro.

Aminocaproates↗
PubMed1992

[The gas chromatographic determination of sulfur- and oxygen-containing organic compounds released into the air of cellulose sulfate works].

The article presents data on the design of sensitive, selective, useful in group analysis method to detect dimethylsulphide, dimethyldisulphide, acetic, propionic, butyric and valeric acids, methyl alcohol and phenol by means of gas chromatography in the air of cellulose sulphate production working zone. The methods were tested in examining the work conditions in Bratsk found-lavage shops.

Air Pollutants, Occupational↗
PubMed1992

Role of NMDA receptors in the compensation of ocular nystagmus induced by hemilabyrinthectomy in the guinea pig.

The possibility that N-methyl-D-aspartate (NMDA) receptor activation plays a role in inducing the vestibular compensation following hemilabyrinthectomy (HL) in guinea pigs, was verified by means of continuous intraventricular osmotic pumping of DL-2-Amino-5-phosphono-valeric acid (APV). Our results show that high doses (40 and 20 mM) of APV decrease both the combined OKR and VOR and the nystagmus following HL. Low doses of APV (2.5 mM), affect the time course of the ocular compensation by maintaining a higher level of nystagmus beat frequency and by delaying the nystagmus disappearance. On the contrary, the compensation time course is not affected by administering APV later on in the compensation period. Therefore, it appears that NMDA receptors are activated during the precocious phase of vestibular compensation, when a large vestibular imbalance is present. This finding is explained by the development of NMDA receptor hypersensitivity, in the functionally inactivated commissural system or by the occurrence of NMDA-mediated long-term potentiation.

2-Amino-5-phosphonovalerate↗
PubMed1977

[Classification of the responses of a giant neuron from the snail Acatina fulica Férussac, caused by inhibitory sugstances depending on chlorine ions].

GABA, three of its derivatives (l-GABOB, d-GABOB and delta-amino valeric acid), acetycholine (Ach), dopamine (DA) and l-Phe-Tyr all inhibit an identifiable giant neurone (the TAN, tonically autoactive neurone) of Achatina fulica. These effects were examined by microdrop application in two different conditions: in physiological solution and in the absence of chloride ions. The results show that the relatively transient (rapid) inhibitions caused by GABA, by its derivatives and by Ach are dependent on chloride ions; the relatively maintained (long-lasting) inhibitions, caused by DA and l-Phe-Tyr, are independent of chloride ions.

Acetates↗
PubMed2003

Sedimentation and prefermentation of domestic wastewater in a fixed bed biofilm reactor.

This investigation was undertaken with the aim of developing a new wastewater prefermentator reactor in order to increase the percentages of sedimentation, hydrolysis and prefermentation of all the organic matter present in the raw wastewater, using only one unit of pre-treatment. The study was carried out using a pilot fixed bed biofilm reactor of 43.3 L in net volume. HRT of 0.5, 1, 2 and 4 h were applied. The reactor has been operating for 403 days during which it has been fed on raw wastewater from the city of Santander, in Spain. The results showed that it is possible to carry out the sedimentation and prefermentation of the organic matter contained in the raw wastewater in this reactor. The TSS average elimination percentage was higher than 50% during the whole testing period. The highest percentage of TSS retained in the reactor was 70% with a HRT of 4 hours and a flow rate of 0.3 m/h. The maximum COD(Total) elimination percentage was 30% for any of the four OL tried. The COD(Particulate) average solubility was greater than 40%. About 44% of the COD(Dissolved) in the effluent consisted of VFA. The highest concentration of VFA measured in the effluent was 44 mg COD/L, applying a HRT of 1 h. The average acidising was slightly higher than 30%. The acetic, propionic, butyric and valeric acids were the species of VFA detected, the acetic acid being the one present in a larger amount (> 50%). The production rate of VFA increases as the HRT decreases.

Biofilms↗
PubMed1988

N-methyl-D-aspartate receptor regulation of uncompetitive antagonist binding in rat brain membranes: kinetic analysis.

N-Methyl-D-aspartate (NMDA) receptor ligands regulate the binding of uncompetitive antagonists in membranes prepared from rat brain. To determine the mechanism of this regulation, we examined the kinetics of the binding of the radiolabeled uncompetitive antagonist [3H]N-(1-[thienyl]cyclohexyl) piperidine (TCP). Increasing concentrations of NMDA receptor agonists produced dose-dependent increases in the association and dissociation rate constants of TCP. The NMDA receptor antagonist amino phosphono valeric acid virtually abolished both the association and dissociation of TCP. Linear regression analysis detected a significant (p less than 0.001) correlation between the effect of NMDA receptor ligands on the apparent association and dissociation rate constants. The most parsimonious explanation of the data is that NMDA receptor ligands regulate TCP binding by controlling access of TCP to a transiently accessible or "guarded" binding site located in the receptor-coupled ion channel. An increase in affinity or number of TCP binding sites is neither necessary nor sufficient to explain the potentiation of TCP binding produced by NMDA agonists. This finding validates the use of uncompetitive antagonist binding as a measure of the functional activation of the NMDA receptor-coupled ion channel in isolated membrane preparations.

Animals↗
PubMed1979

Combined therapy of leukemia La with Damvar and cytostatics.

The new cytostatic drug Damvar, delta-(2-amino-6-hydroxy-3,4-dihydro-4-oxo-5-pyrimidinyl)valeric acid, is not effective in La leukemia system. Damvar given in combination with 5-fluorouracil enhanced the anti-La effect of 5-Fu. There was also enhancement of the antileukemic effect of suboptimal and optimal doses of cyclophosphamide with the addition of Damvar.

Animals↗
PubMed1979

Combined therapy of L1210 leukemia with Damvar and cytostatics.

Damvar, the delta-(2-amino-6-hydroxy-3,4-dihydro-4-oxo-5-pyrimidinyl) valeric acid, administered alone s. c. or i. p., has no effect on L1210 leukemia. In DBA2 mice with L1210, Damvar administered in combination with 5-fluorouracil, or with 6-mercaptopurine, or with cyclophosphamide, in optimal doses, enhances or intensifies the antileukemic effects of the above cytostatics.

Animals↗
PubMedDate not supplied

Phencyclidine metabolism in vitro. The formation of a carbinolamine and its metabolites by rabbit liver preparations.

Four products of the in vitro oxidative metabolism of the piperidine ring of phencyclidine, 5-(1-phenylcyclohexylamino)valeraldehyde, V; N-(1-phenylcyclohexyl)-1,2,3,4-tetrahydropyridine, VIII; 5-(1-phenylcyclohexylamino)valeric acid, VII; and 1-phenylcyclohexylamine, IX, have been identified following derivatization, by GC/MS with stable isotope labeling and/or synthesis. The enamine, VIII, may be a work-up elimination product of a carbinolamine, alpha-hydroxy-N-(1-phenylcyclohexyl)piperidine, IV. The formation of all metabolites requires microsomal enzymes, but VII and the previously described N-(5-hydroxypentyl)-1-phenylcyclohexylamine, VI, also require soluble enzymes. Quantitative or semiquantitative data show that VI and VIII appear and disappear with time, whereas VII seems to be a terminal metabolite.

Animals↗
PubMed1984

Role of substrates and nucleotides in phosphate uptake by rabbit renal cortical cells.

We investigated the viability of isolated rabbit renal cortical cells and the effect of metabolic intermediates on phosphate uptake. Glucose production and its stimulation by hormones was similar to that previously reported for renal tubules. The uptake of alpha-methylglucoside and phosphate was reduced by 90% when sodium was removed from the media. ATP content of the cells was 9.4 +/- 0.7 nmol/mg protein. Succinate and fumarate stimulated phosphate uptake in a dose-dependent manner by 30-60%. Valeric acid (1 mM) and butyric acid (10 mM) stimulated phosphate uptake by 20-30%. Glucose and fructose stimulated phosphate uptake by 18% but only at low concentrations (0.1 mM). Exogenous nucleotides had no effect on phosphate uptake at 0.2 mM, but inhibited 2.4 mM phosphate uptake at 2 mM. We conclude: rabbit renal cortical cells in suspension are metabolically and functionally viable; tricarboxylic acid cycle and glycolytic intermediates as well as short chain fatty acids can stimulate phosphate uptake, and exogenous nucleotides are hydrolyzed to produce free phosphate causing inhibition of isotopic phosphate uptake.

Animals↗
PubMed1982

Pharmacokinetics of Damvar.

The pharmacokinetics of granulated Damvar (delta-(2-amino-6-hydroxy-3,4-dihydro-4-oxo-5-pyrimidinyl) valeric acid) after a single oral dose of 1000 mg was studied in 10 subjects with neoplastic disease. The rate of Damvar absorption from the digestive tract is not very fast. Maximal serum levels (13.5 micrograms/ml) were recorded 3 h after administration with minor interpersonal variations. The time course of Damvar serum concentrations coincides with its distribution in a two-compartmental pharmacokinetic model with biological half-life of 9.72 +/- 0.84 h. Only a small amount of Damvar is eliminated in urine during a period of 24 h (3.1% of the administered dose). Its renal clearance is also low (0.05 ml/s). The analysis of Damvar excretion in urine shows that kidneys play a minor role in its elimination from the body. Therefore the attention should be concentrated on the effect of Damvar administration in patients with disturbed metabolic functions.

Administration, Oral↗
PubMed1997

N-methyl-D-aspartate-mediated glutamate toxicity in the developing rabbit retina.

Extracellular levels of endogenous glutamate are relatively high in the developing rabbit retina but nonetheless appear to promote cell survival and developmental processes at concentrations considered toxic in the adult. We wished to examine the development of retinal susceptibility to glutamate toxicity as well as the protective effects of two N-methyl-D-aspartate (NMDA) antagonists, 2-amino-5-phosphono-5-valeric acid (APV) and dextromethorphan (Dex), and the nitric oxide synthase (NOS) inhibitor, NG-methyl-L-arginine (metARG). One day in vitro retinal explants of adult and neonatal rabbits were incubated with various agonists and antagonists, and stained with trypan blue to visualize necrotic cells. The density of the necrotic cells was analyzed using the Zeiss Videoplan 2. Immature neurons were approximately 10-fold less sensitive to NMDA toxicity compared to the adult. Although both NMDA antagonists and metARG provided marked protection for adult retinal neurons against glutamate toxicity, the modest susceptibility of the immature neuron was blocked only by Dex and not APV or metARG. At least two factors may contribute to the ability of the neonatal retina to survive in the presence of high levels of endogenous extracellular glutamate. First, the 10-fold developmental increase in NMDA toxicity occurs simultaneously with a 12-15-fold downregulation of extracellular glutamate, probably through the actions of maturing Muller cells. Second, the NMDA/NO excitotoxic pathway may not be active at birth since an NOS inhibitor had little effect at this stage and our previous morphological data demonstrate that NOS-containing cells are not present in their mature configuration until the second postnatal week.

2-Amino-5-phosphonovalerate↗
PubMed1997

Modulation of the NMDA receptor by cyanide: enhancement of receptor-mediated responses.

The effect of cyanide on the N-methyl-D-aspartate (NMDA)-stimulated increase in cytosolic free calcium ([Ca++]i) was studied by microfluorescence in fura-2-loaded cerebellar granule cells. The response to NMDA was enhanced by NaCN over a concentration range of 20 to 100 microM. These concentrations of NaCN in the absence of NMDA had no effect on basal [Ca++]i. In comparison, NaCN did not affect K+-depolarization-induced [Ca++]i elevation. The NaCN potentiation of NMDA-evoked [Ca++]i elevation was blocked by addition of Mg++ and by the NMDA receptor antagonists 2-amino-5-phosphono-valeric acid and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohept-5,10-imine maleate. Pretreatment of the cells with pregnenolone sulfate or arachidonate, known modulators of the NMDA receptor, enhanced NaCN action. The voltage-sensitive calcium channel blockers nifedepine and diltiazem did not affect the NaCN-induced potentiation. Additionally, the NaCN action was not altered when tetrodotoxin was used to block Na+ channel-mediated glutamate release. In patch-clamp studies, NaCN increased the amplitude and duration of NMDA-stimulated whole-cell currents. NaCN also enhanced the NMDA receptor response in single-channel patch-clamp experiments. In the outside-out patch recording configuration, NaCN increased the NMDA receptor channel opening frequency without affecting single-channel conductance or mean channel open time. These results indicate that cyanide interacts directly with the NMDA receptor channel complex to enhance receptor-mediated responses.

2-Amino-5-phosphonovalerate↗
PubMed1998

Golgi cells in the superficial granule cell domain overlying the ventral cochlear nucleus: morphology and electrophysiology in slices.

Golgi cells are poised to integrate multimodal influences by participating in circuits involving granule cells in the cochlear nuclei. To understand their physiological role, intracellular recordings were made from anatomically identified Golgi cells in slices of the cochlear nuclei from mice. Cell bodies, dendrites, and terminals for all seven labeled cells were restricted to the narrow plane of the superficial granule cell domain over the ventral cochlear nucleus. The axonal arborization was the most striking feature of all Golgi cells; a dense plexus of terminals covered an area 200-400 microm in diameter in the vicinity of the cell body and dendrites. Axonal beads often surrounded granule cell bodies, indicating that granule cells are probable targets. Cells had input resistances up to 130 M omega and fired regular, overshooting action potentials. Golgi cells probably receive auditory nerve input, because shocks to the cut end of the auditory nerve excited Golgi cells with excitatory postsynaptic potentials (EPSPs). The latency of EPSPs shortened to a minimum and the amplitude of EPSPs grew in several steps as the strength of shocks was increased. The minimum latency of EPSPs in Golgi cells was on average 1.3 milliseconds, 0.6 milliseconds longer than the minimum latencies of EPSPs in nearby octopus and T stellate cells. The long latency raises the possibility that Golgi cells receive input from slowly conducting, unmyelinated auditory nerve fibers. Golgi cells are also excited by interneurons with N-methyl-D-aspartate receptors, probably granule cells, because repetitive shocks and single shocks in the absence of extracellular Mg2+ evoked late EPSPs that were reversibly blocked by DL-2-amino-5-phosphono-valeric acid.

Animals↗
PubMed1999

In vitro percutaneous absorption of fusidic acid and betamethasone 17-valerate across canine skin.

The penetration of betamethasone 17-valerate and fusidic acid through dog skin was measured in vitro. In order to detect the small amounts of diffused compounds, a liquid chromatography-mass spectrometric method was developed with sensitivity limits for both compounds of 5 ng/ml. After application to the skin surface of a topical gel preparation containing these compounds at the anticipated therapeutic dose rate, about 10 per cent of the betamethasone 17-valerate penetrated the skin over a 24-hour period, with no significant metabolism of the ester. About 1.3 per cent of the applied dose of fusidic acid was similarly recovered. The results demonstrated rapid penetration of both compounds through the epidermis.

Administration, Cutaneous↗