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At least 1,099 records · Page 61Linked to original sources
PubMed1971

Aurintricarboxylic acid: inhibitor of initiation of protein synthesis.

Aurintricarboxylic acid prevents the attachment of bacteriophage messenger RNA to ribosomes. As a consequence, initiation of protein synthesis in cell-free extracts prepared from Escherichia coli or rabbit reticulocytes is inhibited at concentrations of dye that do not prevent chain extension. Its properties can be distinguished from other agents that inhibit protein synthesis, including sodium fluoride, cycloheximide, and pactamycin.

Animals↗
PubMedDate not supplied

The effects of GABA-ergic drugs on enkephalin-induced motor seizure phenomena in the rat.

1. The relationship between the effects of GABA-ergic drugs and D-ala2-met-enkephalinamide (DALA)-induced myoclonic contractions of inframandibular muscles has been studied in the rat. 2. GABA-ergic drugs altered enkephalin-induced myoclonic contractions in the following manner: (a) The GABA-mimetic drugs, muscimol, gabaculine and baclofen, decreased DALA-induced myoclonic contractions. (b) The GABA antagonist, bicuculline and the anticonvulsant substance, sodium valproate (dipropylacetic acid, DPA) potentiated DALA-induced myoclonic contractions. The potentiating effect of DPA is probably due to its opiate-like activity, since naloxone abolished this effect. 3. The modulatory effect of the GABA-mimetic drug on enkephalin-induced myoclonic contractions may give grounds for further study to test the possible use of other GABA-mimetic drugs and possibly opiate antagonists for the treatment of myoclonic syndromes.

Animals↗
PubMed1990

Inhibition of phospholipid methylation by an anti-allergic agent, NCO-650, during histamine release.

Antigen, anti-IgE and concanavalin A (Con A) induced an increase in both the incorporation of the 3H-methyl moiety into phospholipids and histamine release. Maximal incorporation of the 3H-methyl moiety into the lipid fraction of the cells was observed within 15 sec and 1 min after being challenged with antigen (100 micrograms/mL) and anti-IgE (200 micrograms/mL) respectively. However, the methylated phospholipid decreased rapidly. The addition of Con A (10 micrograms/mL) also increased phospholipid methylation, which reached a maximum at 5 min after challenge. Trans-4-guanidinomethylcyclohexanecarboxylic acid p-tert-butylphenyl ester hydrochloride (NCO-650; 27 microM) strongly inhibited the incorporation of the 3H-methyl moiety into phospholipid by antigen, anti-IgE and Con A. The IC50 values of NCO-650 for phospholipid methylation in response to antigen, anti-IgE and Con A were 1.5, 4.7 and 1.1 microM respectively. Although the Ca2(+)-ionophore A23187 did not induce phospholipid methylation, it caused histamine release.

Animals↗
PubMed2001

Inhibitors of platelet lipoxygenase from Ponkan fruit.

An activity-guided separation for inhibitors of rat platelet 12-lipoxygenase led to the isolation of two compounds, 4-O-feruloyl-5-O-caffeoylquinic acid (IC50; 5.5 microM) and methyl 4-O-feruloyl-5-O-caffeoylquinate (IC50; 1.9 microM) from the peel of Ponkan fruit (Citrus reticulata). The complete structure of each phenolic ester was determined by NMR spectroscopy [1H and 13C NMR spectra, 1H-1H correlation spectroscopy (COSY), 1H-detected heteronuclear multiple quantum coherence (HMQC), and heteronuclear multiple bond connectivity (HMBC) spectroscopies] and other spectral methods.

Animals↗
PubMed1976

Podophyllotoxin analogs. 1. Synthesis and biological evaluation of certain trans-2-aryl-trans-6-hydroxymethyl-3-cyclohexenecarboxylic acid gamma-lactones as antimitotic agents.

A series of cis and trans bicyclic lactones was prepared as congeners of podophyllotoxin (1) and evaluated as antimitotic agents both in cell cultures grown in vitro and in an in vitro protein binding assay. All compounds displayed insignificant activity-a result which may reflect insufficient structural similarity to podophyllotoxin or which may be interpreted as in agreement with previous observations of the stereochemical requirements for antimitotic activity defined for 1.

Animals↗
PubMed1983

Reduction of gastric haemorrhage by fibrinolysis inhibition - an experimental study in rats.

Gastric ulcerations were induced in rats by pyloric ligature and instillation of 1.0 N HCl. After four hours all rats had developed ulcerations. Increased release of plasminogen activators from the mucosa during these conditions has previously been demonstrated. In the present study we investigated the role of fibrinolysis inhibition versus H2-receptor blockade on the gastric bleeding. Tranexamic acid - a synthetic inhibitor of the fibrinolytic system - was found to significantly (p less than 0.01) reduce blood loss into the gastric juice by 30% measured by 51Cr labelled red blood cells; cimetidine did not reduce the gastric haemorrhage under the experimental conditions used. Both treatment regimes significantly (p less than 0.02) reduced the secretion of gastric juice. These results indicate a contribution of the fibrinolytic system in gastric bleeding from experimentally induced gastric ulcerations.

Animals↗
PubMed1990

A trypsin-like proteinase appearing at 17 h and 17 min in the cell cycle time of HeLa cells correlates with the onset of DNA synthesis.

A trypsin-like proteinase appearing sharply at 17 h 17 min (17:17) in the cell cycle time of the synchronized and growing HeLa cells correlates with the onset of DNA synthesis, and the inhibition of the proteinase activity by trans-4-guanidinomethylcyclohexanecarboxylic acid 4-tert-butylphenyl ester (GMCHA-OPhBut) results in a 3 h retardation of the onset of the DNA synthesis. The proteinase activity is cell density dependent and completely inhibited by 100 microM GMCHA-OPhBut. The proteinase was named HeLa tryptase 17:17. The fact that the DNA synthesis occurred after the 3 h retardation in the presence of GMCHA-OPhBut strongly suggests the involvement of the alternative trigger for DNA synthesis in HeLa cells.

Cell Cycle↗
PubMed1989

Effect of plasmin inhibitors on gastric mucosal permeability in rats.

We examined the protective effect of plasmin inhibitors on gastric mucosal vascular permeability in rats. Tranexamic acid and aminocaproic acid significantly inhibited the increase in vascular permeability and macroscopic gastric mucosal lesions induced by 50% ethanol and 1% ammonia. The protective effect afforded by plasmin inhibitors was not affected by pretreatment with indomethacin. Our results show that plasmin inhibitors inhibit the increase in gastric vascular permeability and suggest that plasmin may play an important role in the pathogenesis of gastric mucosal damage.

Aminocaproates↗
PubMed1984

Lack of effect of tranexamic acid on rheumatoid arthritis.

In a double-blind controlled study on 45 rheumatoid arthritis patients, no effect of tranexamic acid (Cyklocapron, 4.5 g per day for 6 weeks) was found in terms of subjective or objective parameters of disease activity. Tranexamic acid did not reduce complement activation, measured by plasma concentrations of the complement C3 split product C3d. Immune complex concentrations in serum were also unaffected. We conclude that plasmin inhibitors do not reduce immune complex mediated complement activation, and they should not be used for treatment of rheumatoid arthritis.

Adult↗
PubMed2003

Preclinical evaluation of the pharmacokinetics, brain uptake and metabolism of E121, an antiepileptic enaminone ester, in rats.

The present study describes the brain uptake, pharmacokinetics and metabolism of an anticonvulsant enaminone ester E121, which belongs to a new and active series of compounds with potential in vivo anticonvulsant activity in rodent models, in rats. A single dose of E121 was administered i.p. to male Sprague Dawley rats at 10 mg E121/kg body weight. Cohorts of animals (n=3) were killed at varying times over 0-24 h to collect plasma and brain samples. Urinary excretion of E121 was studied in a separate group of five rats at the same dose. A validated HPLC method was used to quantify E121 and its metabolites in plasma, brain and urine. LC-MS/MS was used to characterize the metabolites. The plasma and brain Cmax of 11.0+/-3.0 mg/l and 10.4+/-1.4 mg/kg, respectively, were observed for E121 at 15 min post dose and they declined in a mono-exponential fashion. The plasma Cl/F and t1/2 were 0.57 l/h/kg and 0.75 h, respectively. The brain uptake ratio of E121 was 0.9. Mass spectral analysis of urine showed two major metabolites (m/z 280) and one minor metabolite (m/z 236) that were consistent with initial hydrolysis of the compound to the acid followed by further decarboxylation and appears to be the major route of elimination of E121. The rapid and moderate brain uptake of E121 correlates well with its potential anticonvulsant activity (ED50 3.0 mg/kg p.o. in rats). The brain uptake, pharmacokinetic and metabolic profile of E121 supports the need to further evaluate this compound for its potential as an antiepileptic.

Aniline Compounds↗
PubMed1999

Isolation and characterization of the product of inactivation of gamma-aminobutyric acid aminotransferase by gabaculine.

Gabaculine (5-amino-1,3-cyclohexadienylcarboxylic acid, 1), a naturally occurring neurotoxin isolated from Streptomyces toyocaenis, has been shown to be a mechanism-based inactivator of gamma-aminobutyric acid aminotransferase (GABA-AT) (Rando, R. R. Biochemistry 1977, 16, 4604). Inactivation results from reaction of gabaculine with the pyridoxal 5'-phosphate (PLP) cofactor. Two HPLC systems for isolating this inactivator-PLP adduct are described as well as a detailed characterization of the adduct, including the ultraviolet-visible spectrum, electrospray mass spectra, and NMR spectrum. The same spectral characterization of the chemically synthesized gabaculine-PLP adduct is also reported.

4-Aminobutyrate Transaminase↗
PubMed2003

Two cases of occupational allergic contact dermatitis from a cycloaliphatic epoxy resin in a neat oil: case report.

BACKGROUND: Metal-working fluids contain complex mixtures of chemicals and metal workers constitute a potential risk group for the development of allergic contact dermatitis. CASE PRESENTATION: Two metal workers developed allergic contact dermatitis on the hands and lower arms from exposure to a neat oil used in metal processing. Patch testing revealed that the relevant contact allergen was a cycloaliphatic epoxy resin, 1,2-cyclohexanedicarboxylic acid, bis(oxiranylmethyl) ester, added to the oil as a stabilizer. None of the patients had positive reactions to the bisphenol A-based epoxy resin in the standard series. CONCLUSIONS: These cases emphasize that well-known contact allergens may show up from unexpected sources of exposure. Further, it can be a long-lasting, laborious process to detect an occupational contact allergen and cooperation from the patient and the manufacturer of the sensitizing product is essential.

Allergens↗
PubMed1989

Intestinal lymphangiectasia markedly improved with antiplasmin therapy.

A 35-yr-old woman with intestinal lymphangiectasia was treated with trans-4-aminomethyl cyclohexane carboxylic acid. After 6 wk of antiplasmin therapy, her serum total protein increased to normal levels and 131I-polyvinyl pyrrolidone excretion was also normalized. With a daily administration of trans-4-aminomethyl cyclohexane carboxylic acid, the patient has manifested no symptoms for 8 yr up to the present. Throughout the clinical course, the values for euglobulin lysis time showed a close relationship to changes in serum total protein. It was then suggested that increased plasma fibrinolysis may enhance lymphatic permeability to plasma proteins. During this treatment, a decreased percentage of T lymphocytes became normalized together with serum immunoglobulin values. In addition, the therapy has resulted in the disappearance of duodenal lesions observed endoscopically.

Adult↗
PubMed1970

Physiological and kinetic studies with anthranilate synthetase of Bacillus alvei.

Anthranilate synthetase from Bacillus alvei was partially purified by ammonium sulfate fractionation and was stabilized by glycerol. The reaction mechanism of the enzyme was found to be sequential with respect to substrate, and the enzyme formed a hydroxamic acid in the absence of Mg(++). The K(m) for chorismic acid was 1.25 x 10(-4)m, and the K(m) for l-glutamine was 5.5 x 10(-4)m. Enzyme activity was inhibited by tryptophan noncompetitively with respect to chorismic acid and uncompetitively with respect to l-glutamine. An analysis of the inhibition patterns indicated that tryptophan may act as a dead end inhibitor and bind at the catalytic site. Enzyme activity could be completely inhibited in vitro and in vivo under the appropriate conditions, and enzyme synthesis was sensitive to repression by tryptophan. A sedimentation coefficient of 5.5S and an estimated molecular weight of 90,000 were obtained for the enzyme.

Bacillus↗
PubMed1990

Chiral synthon obtained with pig liver esterase: introduction of chiral centers into cyclohexene skeleton.

A versatile chiral synthon, (1R,6S)-6-methoxycarbonyl-3-cyclohexene-1-carboxylic acid, was obtained by an enantioselective hydrolysis of the corresponding meso diester with pig liver esterase. This enzymatic hydrolysis can easily be carried out on a multi-hundred gram scale. The chiral monoester thus obtained can be further converted into all stereoisomers of 1-amino-2-alkoxycarbonyl-4-cyclohexene derivatives in an enantio- and stereocontrolled manner. These derivatives are considered as potential key intermediates for synthesizing a variety of biologically interesting compounds such as aminocyclitol and carbapenem antibiotics.

Animals↗
PubMed2002

Gabapentin. Pfizer.

Gabapentin has been approved for the treatment of neuropathic pain in six European countries, New Zealand and Australia, and numerous countries in Latin America. By January 2001, Pfizer was preparing to file an NDA in the US for this indication; by October 2001, this NDA had been filed with the FDA. The drug is a GABA analog, but is not a GABA mimetic, although some neurons that respond to gabapentin are GABAergic. Gabapentin, at relevant concentrations, binds to an auxiliary protein of voltage-gated calcium channels (a2/3) and apparently, as a result, modulates the action of calcium channels and neurotransmitter release. This may account for many of its pharmacological actions. Gabapentin is also a substrate for the large neutral amino acid transporter, and this may be the major route allowing gabapentin access to the CNS. Modulation of synaptic transmission between primary afferents and substantia gelatinosa neurons, and blockade of signal transduction, are two potential mechanisms of action, in addition to inhibition of glutamate release by voltage-sensitive calcium channels. In September 2001, Morgan Stanley predicted sales of US $1871 million in 2002 falling to US $413 million in 2006.

Acetates↗
PubMed1996

Activity-dependent transport of GABA analogues into specific cell types demonstrated at high resolution using a novel immunocytochemical strategy.

We have raised antisera against the GABA analogues gamma-vinyl GABA, diaminobutyric acid and gabaculine. These analogues are thought to be substrates for high-affinity GABA transporters. Retinae were exposed to micromolar concentrations of these analogues in the presence or absence of uptake inhibitors and then fixed and processed for immunocytochemistry at the light and electron microscopic levels. Immunolabelling for gamma-vinyl GABA revealed specific labelling of GABAergic amacrine cells and displaced amacrine cells in retinae of rabbits, cats, chickens, fish and a monkey. GABA-containing horizontal cells of cat and monkey retinae failed to exhibit labelling for gamma-vinyl GABA, suggesting that they lacked an uptake system for this molecule. In light-adapted fish, gamma-vinyl GABA was readily detected in H1 horizontal cells; similar labelling was also observed in light-adapted chicken retinae. The pattern of labelling in the fish and chicken retinae was modified by dark adaptation, when labelling was greatly reduced in the horizontal cells, indicating the activity dependence of GABA (analogue) transport. Intraperitoneal injection of gamma-vinyl GABA into rats resulted in its transport across the blood-brain barrier and subsequent uptake into populations of GABAergic neurons. The other analogues investigated in this study exhibited different patterns of transport; gabaculine was taken up into glial cells, whilst diaminobutyric acid was taken up into neurons, glial cells and retinal pigment epithelia. Thus, these analogues are probably substrates for different GABA transporters. We conclude that immunocytochemical detection of the high-affinity uptake of gamma-vinyl GABA permits the identification of GABAergic neurons which are actively transporting GABA, and suggest that this novel methodology will be a useful tool in rapidly assessing the recent activity of GABAergic neurons at the cellular level.

Adaptation, Ocular↗
PubMed1998

Advances in the medical treatment of epilepsy.

Treatment options for epilepsy, especially using antiepileptic drugs, have increased substantially in the past five years. Since 1993, four novel antiepileptic drugs have been approved and marketed in the United States: felbamate, gabapentin, lamotrigine, and topiramate. Two others, tiagabine and vigabatrin, are likely to be approved in the near future. For many patients, these agents offer the realistic promise of improved seizure control, often with fewer adverse effects and less significant drug interactions compared with older agents. In addition, fosphenytoin, a water-soluble phenytoin prodrug with a number of advantages over intravenous phenytoin, has been released. There are new administration options for carbamazepine, diazepam, and valproic acid. For drug-resistant or -intolerant patients, there has been renewed interest in alternative therapies, especially the ketogenic diet. Taken together, these represent significant therapeutic advances that are benefiting patients with epilepsy. At the same time, improved understanding of the basic mechanisms of epileptogenesis, and of the cellular and molecular actions of available antiepileptic drugs, creates a framework for designing unique therapeutic strategies that are targeted at key sites of vulnerability involved in the development and maintenance of the epileptic state.

Acetates↗