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At least 307 records · Page 17Linked to original sources
PubMed1983

Co-accumulation of prephenate, L-arogenate, and spiro-arogenate in a mutant of Neurospora.

A mutant strain of Neurospora crassa blocked in each of the initial steps of tryptophan, tyrosine, and phenylalanine biosynthesis was previously shown to accumulate and secrete prephenate and L-arogenate (Jensen, R.A., Zamir, L.O., St. Pierre, M., Patel, N., and Pierson, D.L. (1977) J. Bacteriol. 132, 896-903). We now report the co-accumulation of yet another compound which was identified (Zamir, L.O., Tiberio, R., Jung, E., and Jensen, R.A. (1982) J. Biol. Chem. (1983) 258, 6486-6491) as the lactam derivative of L-arogenate. This structure, spiro-arogenate, undergoes a facile acid-catalyzed conversion to L-phenylalanine (as does L-arogenate). Since L-arogenate is conveniently quantitated as 5-dimethylaminonapthalene-1-sulfonyl (dansyl)-phenylalanine following acidification and dansylation, the unknown presence of spiro-arogenate may easily lead to overestimation of L-arogenate present in mixtures. Reliable quantitative assays for both L-arogenate and spiro-arogenate in mixtures were designed utilizing [3H]dansyl-chloride and exploiting the inability of the spiro-arogenate molecule to be dansylated in contrast to L-arogenate. The initial appearance of spiro-arogenate during accumulation lagged behind prephenate and L-arogenate, and spiro-arogenate accumulation leveled off after 5 days while prephenate and L-arogenate accumulations continued. It seems likely that spiro-arogenate is derived directly from L-arogenate. Prephenate, L-arogenate, and spiro-arogenate comprised about 70, 15, and 15% fractions of the total accumulation in a representative accumulation experiment designed to maximize spiro-arogenate yields. Modest variations in co-metabolite ratios were obtained under nutritional conditions where carbon source, growth temperature, duration of incubation time, and amino acid additions were experimental variables.

Amino Acids↗
PubMed1975

[Cytotoxicity of aurintricarboxylic acid: inhibition of cell proliferation and of protein synthesis in Allium sativum L. root meristems].

The inhibitory action of aurine-tricarboxylic acid (ATA) on protein synthesis, known in vitro, has been checked in vivo in Allium sativum L. root meristems. Parallel to this inhibition, ATA acts on cell proliferation, on the one hand by preventing the entering of cells into prophase and, on the other hand, by disturbing the process of mitosis.

Aurintricarboxylic Acid↗
PubMed2000

Gabapentin for drug-resistant partial epilepsy.

BACKGROUND: The majority of epileptic patients have a good prognosis and their seizures can be well controlled with the use of a single antiepileptic agent, but up to 30% develop refractory epilepsy, especially those with partial seizures. In this review we summarise the current evidence regarding a new antiepileptic drug, gabapentin, when used as an add-on treatment for drug-resistant partial epilepsy OBJECTIVES: To evaluate the efficacy and tolerability of gabapentin when used as an add-on treatment for patients with drug-resistant partial epilepsy. SEARCH STRATEGY: We searched the Cochrane Epilepsy Group trial register, the Cochrane Controlled Trials Register of The Cochrane Library Issue 4, 1998. In addition, we contacted Parke Davis (manufacturers of gabapentin) and experts in the field to seek any ongoing studies or unpublished studies. SELECTION CRITERIA: Randomized placebo controlled double blind add-on trials of gabapentin in patients with drug-resistant partial epilepsy. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected trials for inclusion and extracted the relevant data. The following outcomes were assessed: (a) 50% or greater reduction in seizure frequency; (b) treatment withdrawal (any reason); (c) side effects. Primary analyses were intention to treat. Sensitivity best and worst case analyses were also undertaken. Summary odds ratios were estimated for each outcome. Dose response was evaluated in regression models, and Number Needed to Treat (NNTs) were calculated for individual doses. MAIN RESULTS: Four trials were included representing 750 randomized patients. EFFICACY: Overall odds ratio (OR) (95% Confidence Interval (CI)) for 50% or greater reduction in seizure frequency compared to placebo 2.22 (1.49 - 3.32). Dose regression analysis shows increasing efficacy with increasing dose, with 28.5% (21.5 - 36.7) of patients responding to 1800mg of gabapentin compared to placebo, NNT 6.7 (3.0 - 10.5). Global effectiveness: treatment withdrawal OR (95% CI) compared to placebo 1.40 (0.76 - 2.55); Side effects: OR (99% CI) compared to placebo. dizziness 2.26 (1.28 - 3.99); fatigue 2.29 (1.11 - 4.74); somnolence 2.04 (1.21 - 3.45) were significanty associated with gabapentin. REVIEWER'S CONCLUSIONS: Gabapentin has efficacy as an add-on treatment in patients with drug-resistant partial epilepsy. However, trials reviewed were of relatively short duration, and provide no evidence for the long term efficacy of gabapentin. Results cannot be extrapolated to monotherapy or patients with other epilepsy types.

Acetates↗
PubMed1998

SB 207499 (Ariflo), a potent and selective second-generation phosphodiesterase 4 inhibitor: in vitro anti-inflammatory actions.

First-generation phosphodiesterase 4 (PDE4) inhibitors, such as rolipram, inhibit the activation of immune and inflammatory cells. The clinical use of these compounds is limited by gastrointestinal side effects, such as increased acid secretion and nausea. Consequently, the challenge has been to design novel PDE4 inhibitors that maintain the anti-inflammatory actions of rolipram while achieving an improved side effect profile. Among the first of this new class of PDE4 inhibitors specifically designed to have an improved therapeutic index relative to earlier compounds is SB 207499 (Ariflo) [c-4-cyano-4-(3-cyclopentyloxy-4-methoxy-phenyl)-r-1-cyclohexanecarboxyl ic acid]. In this study, we compared the anti-inflammatory and gastric secretogogue activities of SB 207499 with those of rolipram. The cellular models used were (1) histamine release from human basophils, (2) tumor necrosis factor-alpha generation in human monocytes, (3) degranulation of human neutrophils, (4) antigen-driven proliferation and cytokine synthesis from human T cells and (5) acid secretion from isolated rabbit gastric glands. SB 207499 inhibited the activation of a variety of immune and inflammatory cells in a concentration-dependent manner: (1) histamine release in basophils [-log IC25 = 6.6 +/- 0.3 vs. 8.0 for (R)-rolipram], (2) lipopolysacchride-induced TNF-alpha formation in monocytes [-log IC50 = 7.0 +/- 0.1 vs. 7.2 +/- 0.1 for (R)-rolipram], (3) fMLP-induced degranulation in neutrophils [-log IC15 = 7.1 +/- 0.2 vs. 6.4 +/- 0.5 for (R)-rolipram], (4) house dust mite induced-proliferation of peripheral blood mononuclear cells [-log IC40 = 6.5 +/- 0.3 vs. 6.4 +/- 0.3 for (R)-rolipram] and (5) ragweed-induced production of interferon-gamma [-log IC50 = 5.4] and interleukin-5 [-log IC50 = 5.0]. Although SB 207499 inhibits the activation of a variety of immune and inflammatory cells with a potency equal to that of rolipram, it is > 100-fold less potent than the latter compound as an acid secretagogue [-log EC50 = 6.1 +/- 0.1 vs. 8.3 +/- 0.2 for (R)-rolipram]. Collectively, these data indicate that SB 207499 retains the anti-inflammatory activity of the prototypical PDE4 inhibitor rolipram but is substantially less likely to stimulate gastric acid secretion.

Animals↗
PubMed2006

Selective transport of Pb2+ and Cd2+ across a phospholipid bilayer by a cyclohexanemonocarboxylic acid-capped 15-crown-5 ether.

A cyclohexanemonocarboxylic acid-capped 15-crown-5 ether was synthesized and found to be effective as an ionophore for Pb2+ and Cd2+, transporting them across a phospholipid bilayer membrane. Transport studies were carried out using 1-palmitoyl-2-oleoyl-sn-glycerophosphatidylcholine (POPC) vesicles containing the chelating indicator 2-([2-bis(carboxymethyl)amino-5-methylphenoxy]methyl)-6-methoxy-8-bis(carboxymethyl)aminoquinoline (Quin-2). Data obtained at pH 7.0 using this system, show that the synthetic ionophore transports divalent cations with the selectivity sequence Pb2+ > Cd2+ >> Zn2+ > Mn2+ > Co2+ > Ni2+ > Ca2+ > Sr2+. Selectivity factors, based on the ratio of individual initial cation transport rates, are 280 (Pb2+/Ca2+), 62 (Pb2+/Zn2+), 68 (Cd2+/Ca2+), and 16 (Cd2+/Zn2+). Plots of log initial rate versus logM(n+) or log ionophore concentration suggest that Pb2+ and Cd2+ are transported primarily as a 1:1 cation-ionophore complex, but that complexes with other stoichiometries may also be present. The ionophore transports Pb2+ and Cd2+ by a predominantly electrogenic mechanism, based upon an enhanced rate of transport that is produced by agents which dissipate transmembrane potentials. The rate of Pb2+ transport shows a biphasic pH dependence with the maximum occurring at pH approximately 6.5. The high selectivity for Pb2+ and Cd2+ displayed by the cyclohexanecarboxylic acid-capped 15-crown-5 ether suggests potential applications of this ionophore for the treatment of Pb and Cd intoxication, and removal of these heavy metals from wastewater.

Cadmium↗
PubMed1983

Kinetic analysis of the accumulation of gamma-aminobutyric acid by particulate fractions of rat brain: comparison of the effects of nipecotic acid and cis-3-aminocyclohexane-1-carboxylic acid.

Kinetic analyses indicate that nipecotic acid and cis-3-aminocyclohexane-1-carboxylic acid (cis-3-ACHC) inhibit GABA accumulation by similar mechanisms of action. Both amino acids are competitive inhibitors of particulate GABA accumulation when GABA and the inhibitor are added simultaneously to tissue fractions. However, preincubating the tissue with either amino acid produces noncompetitive inhibition of GABA accumulation at low concentrations of inhibitor and mixed inhibition at higher concentrations. The possible roles of intrasynaptosomal mechanisms and of astroglia in producing these effects are discussed. The most notable difference between cis-3-ACHC and the other amino acid inhibitors of GABA accumulation, such as nipecotic acid, cis-4-OH-nipecotic acid, guvacine, beta-proline, homo-beta-proline, and 2,4-diaminobutyric acid (DABA), is that cis-3-ACHC is approximately 3.5 times more potent as an inhibitor following preincubation. Thus, while cis-3-ACHC does inhibit GABA transport, its major site of action in the synaptosome may be intracellular.

Amino Acids↗
PubMed2006

Determination of drug binding to plasma proteins using competitive equilibrium binding to dextran-coated charcoal.

A method for determination of drug binding to plasma proteins, which is based on the comparison of drug affinities to plasma proteins and dextran-coated charcoal, is described. The method is free of nonspecific binding feature. The fractions unbound obtained by the charcoal method are in good agreement with values from a traditional ultrafiltration method for various low and highly bound compounds. The method presently requires drug concentrations much less than that of plasma proteins. A possibility of using the method to determine protein binding at an arbitrary drug concentration is discussed. A mechanism of nonspecific binding of drug to ultrafiltration membranes, which yields a good agreement with experimental observations, is suggested.

Adsorption↗
PubMed1987

Stimulation of transcription and translation by aurin tricarboxylic acid in mitochondrial lysates from Ehrlich ascites cells.

We have prepared a submitochondrial fraction from Ehrlich ascites tumor cell mitochondria which shows transcription and translation activities. The antibiotic aurin tricarboxylic acid (ATA) at low concentrations induces both RNA and protein synthetic activities of the mitochondrial lysate by several fold. At high concentrations, however, ATA inhibits the translation activity but continues to stimulate the transcription activity in a dose dependent manner up to 0.5 mM concentration tested. The lysate system transcribes endogenous DNA yielding RNA species resembling control mitochondrial RNA and synthesizes authentic cytochrome oxydase I and cytochrome oxidase II subunits.

Animals↗