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PubMed2004

Melaminium maleate monohydrate.

In the title compound, 2,4,6-triamino-1,3,5-triazin-1-ium maleate monohydrate, C3H7N6+.C4H3O4-.H2O, containing singly protonated melaminium residues, maleate(1-) anions and water molecules, the components are linked by hydrogen bonds into a three-dimensional framework structure. The melaminium residues are connected by two pairs of N-H...N hydrogen bonds into chains in the form of stacks, with a distance of 3.26 (1) A between the triazine rings, clearly indicating pi-pi interactions. The maleate anion contains an intramolecular O-H...O hydrogen bond and the anions interact with the water molecules via O-H...O hydrogen bonds, forming zigzag chains, also in the form of stacks, in which the almost-planar maleate anions are separated by 3.26 (1) A. The experimental geometries of the ions are compared with molecular-orbital calculations of their gas-phase geometries.

Journal Article↗
PubMed1993

Purification and Characterization of Maleate Hydratase from Pseudomonas pseudoalcaligenes.

Maleate hydratase (malease) from Pseudomonas pseudoalcaligenes has been purified. The purified enzyme (98% pure) catalyzes the stereospecific addition of water to maleate and citraconate (2-methylmaleate), forming d-(+)-malate and d-(+)-citramalate, respectively. 2,3-Dimethylmaleate was also a substrate for malease. The stability of the enzyme was dependent on the protein concentration and the addition of dicarboxylic acids. The purified enzyme (89 kDa) consisted of two subunits (57 and 24 kDa). No cofactor was required for full activity of this colorless enzyme. Maximum enzyme activity was measured at pH 8 and 45 degrees C. The K(m) for maleate was 0.35 mM, and that for citraconate was 0.20 mM. Thiol reagents, such as p-chloromercuribenzoate and iodoacetamide, and sodium dodecyl sulfate completely inhibited malease activity. Malease activity was competitively inhibited by d-malate (K(i) = 0.63 mM) and d-citramalate (K(i) = 0.083 mM) and by the substrate analog 2,2-dimethylsuccinate (K(i) = 0.025 mM). The apparent equilibrium constants for the maleate, citraconate, and 2,3-dimethylmaleate hydration reactions were 2,050, 104, and 11.2, respectively.

Journal Article↗
PubMed1990

A scanning electron microscopic investigation of bonding of methacryloyloxyalkyl hydrogen maleate to etched dentin.

Three types of methacryloyloxyalkyl hydrogen maleates--2-(methacryloyloxy)ethyl hydrogen maleate (2MEM), 1-(methacryloyloxy-methyl)ethyl hydrogen maleate (MMEM), and 1-(methacryloyloxymethyl)propyl hydrogen maleate (MMPM)--were prepared for use as bonding agents. The relationships between the thickness of an acid-proof dentin layer and the bond strength and chemical structure of the synthesized monomers were investigated. The bond strengths of 2MEM/composite system to dentin treated with either 37% phosphoric acid solution or 10% citric acid-3% ferric chloride solution (10-3 solution) were superior to those of the others. The acid-proof dentin layer for all bonding agents containing the synthesized monomers at the resin-dentin interface was clearly visible in a scanning electron microscope, regardless of the types of dentin etching agents used. After treatment of the dentin with the phosphoric acid solution, the layers of 2MEM, MMEM, and MMPM were 5-6 micron, 3-4 micron, and 2-3 micron thick, respectively. When the dentin was treated with the 10-3 solution, the layer for each bonding agent was approximately 1 micron thick.

Acid Etching, Dental↗
PubMed1979

Treatment of variant angina pectoris with perhexilene maleate.

Three patients with variant angina pectoris resistant to therapy with nitrates and propranolol were treated with perhexilene maleate. Two patients had normal coronary arteries with documented coronary artery spasm, while the third patient had a fixed coronary artery obstruction. In all three patients, attacks of variant angina pectoris disappeared following institution of therapy with perhexilene maleate. When the dose of this drug was decreased to 100 mg per day or less, symptoms reappeared in all patients. Reinstitution of therapeutic doses of perhexilene maleate once again resulted in complete control of symptoms. Perhexilene maleate is therefore a useful agent for the treatment of variant angina pectoris.

Angina Pectoris↗
PubMed1979

Perhexiline maleate in the treatment of severe angina pectoris.

Perhexiline maleate was used as a prophylactic agent in 26 patients suffering from severe angina pectoris. The mean duration of treatment was 8.9 months, with a maximum of 28 months. Fifteen patients experienced a reduction in frequency of attacks to less than one-third of their previous level; six experienced a reduction to two-thirds of their previous level; no patient showed an increase in attack rates. During the period of study, there was one death. Frequently observed side effects included dizziness, gastrointestinal irritation and malaise. One patient developed clinically apparent hepatic dysfunction which resolved on withdrawal of perhexiline maleate, but recurred after rechallenge with a lower dose of the drug; the results of liver function tests in five others showed mild abnormalities. One patient developed peripheral neuropathy after taking perhexiline maleate for 18 months, but this resolved in two months after cessation of therapy. Good responses to perhexiline maleate were observed in patients who were concurrently treated with beta-adrenoreceptor blocking drugs.

Alprenolol↗
PubMed2000

[Effect of enalapril maleate on vascular endothelial function and platelet-endothelial interactions in patients with essential hypertension].

AIM: Evaluation of endothelial function and platelet-endothelial interactions in patients with essential hypertension and dynamics of these changes in the course of treatment with enalapril maleate. MATERIALS AND METHODS: The study included 37 patients with essential hypertension and 22 normotensive volunteers. 17 of hypertensive patients received enalapril maleate (enap, KRKA) 5-20 mg/day during the period of 1.5 months. The complex of investigations included: measurement of total plasma cholesteroi, 12-lead ECG, echocardiography, high-resolution ultrasound investigation of brachio-cephalic arteries, evaluation of flow-mediated dilation, measurement of von Willebrand's factor, spontaneous and induced platelet aggregation. RESULTS: Patients with essential hypertension exhibited higher levels of von Willebrand's factor in plasma and degree of spontaneous and induced platelet aggregation as well as lower responses of vessel wall to hemodynamic stimuli compared to normotensive healthy individuals. There was a strong correlation between endothelial function markers and CAD risk factors, elevation of platelet activity. Treatment with enalapril maleate led to a statistically significant decrease of von Willebrand's factor in plasma and ex vivo platelet aggregation whereas flow-mediated dilatation increased. Values of endothelial function markers and platelet activity approached to those of normotensive subjects and these changes were accompanied by a decrease of ECG signs of left ventricular hypertrophy. CONCLUSION: Patients with essential hypertension were found to have compromised endothelial function. However, the degree of endothelial dysfunction depends not on hemodynamic parameters, but on the cumulative effect of CAD risk factors. Treatment with enalapril maleate may lead to normalisation of endothelial function and decrease of platelet activity.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Evaluation of efficacy and safety of losartan potassium in the treatment of mild to moderate hypertension as compared to enalapril maleate.

AIM: To study the effect of losartan potassium in the treatment of mild to moderate hypertension and to compare its efficacy and adverse effect profile with enalaparil maleate. MATERIAL AND METHODS: One hundred and forty five patients with mild to moderate essential hypertension were enrolled in this randomized, double blind, controlled, parallel and multicentric study. Seventy two patients received losartan potassium 50 mg and seventy three received enalapril maleate 5 mg. RESULTS: Losartan potassium reduced the DBP to < 90 mm Hg in 59% of the patients at the end of 8 weeks compared to 45% in the enalapril maleate group. DBP was reduced by 10 or > than 10 mm Hg in 89% of the patients with losartan as compared to the baseline whereas it was 80% in the enalapril group. Percentage of side effects seen in losartan and enalapril groups were 12 and 22 respectively. CONCLUSION: Losartan potassium is an efficacious antihypertensive agent in mild to moderate hypertension. It also has fewer side effects when compared to enalapril maleate.

Adult↗
PubMed1992

Post-irradiation protective effect of irsogladine maleate on intestinal crypt stem cells in mice.

Radioprotective effect of irsogladine maleate, an anti-ulcer drug, on the intestinal crypt stem cell survival was studied in mice using a crypt microcolony assay. Irsogladine maleate was injected intraperitoneally immediately after irradiation and then, daily for three days. A successive administration of the drug following 10 Gy of irradiation increased the survival of intestinal stem cells with a clear dose-related trend. In order to estimate the D0, survival curves were determined for X-ray plus placebo and X-ray plus 10 mg/kg of irsogladine maleate. The D0, for X-ray plus the drug was 2.2 Gy while it was 1.9 Gy for X-ray plus placebo. These findings suggest that isogladine maleate can be applied for the alleviation of intestinal damages in heavily irradiated people by radiation accidents.

Animals↗
PubMed1979

Perhexiline maleate-induced cirrhosis.

The authors report the cases of 2 patients who died from cirrhosis after receiving perhexiline maleate, a drug widely used in Europe for the treatment of angina pectoris. Perhexiline maleate had been ingested for 24 and 28 mo, respectively. Manifestations of cirrhosis included jaundice, hepatic encephalopathy, ascites, and portal hypertension. Associated manifestations of intolerance to perhexiline maleate included peripheral neuropathy in 1 patient and marked weight loss in both. Histologic lesions resembled those observed in patients with alcoholic liver disease. Ultrastructural lesions included numerous enlarged lysosomes containing myeloid figures. Histochemical stains demonstrated increased phospholipid content of the hepatocytes. These findings are consistent with the view that prolonged administration of perhexiline maleate may induce both histologic lesions resembling those of alcoholic liver disease and ultrastructural and histochemical lesions resembling those of phospholipidosis.

Aged↗
PubMed1988

Inhibition of (Na+,K+)-ATPase and Mg++-ATPase by a lysosomotropic drug: perhexiline maleate.

Human clinical observations and in vivo studies have shown that the amphiphilic drug perhexiline maleate is responsible for lipidosis storage disorders. When the drug was incubated in vivo with rat brain homogenates, the ouabain-sensitive (Na+,K+)-ATPase and the Mg++-ATPase activities were inhibited. 50% inhibition occurred at the drug concentrations 5.10(-5) M for (Na+,K+)-ATPase and at 10(-4) M for Mg++-ATPase, respectively. Kinetic studies performed on rat brain homogenates showed a mixed type inhibition of these enzymes by perhexiline maleate. The effect of other lysosomotropic drugs (imipramine, chlorpromazine, thioridazine and tamoxifen) on (Na+,K+)-ATPase and on Mg++-ATPase activities was found to be similar to that induced by perhexiline maleate. These results indicate that the inhibitory effect of perhexiline maleate on (Na+,K+)-ATPase and Mg++-ATPase may be a common feature shared by the lysosomotropic drugs.

Animals↗
PubMed1978

Perhexiline maleate in the treatment of angina pectoris. Five years of personal clinical experience.

A five-year personal experience of the use of perhexiline maleate (Pexid) in the treatment of severe angina pectoris is presented. Ninety-four patients, all severely incapacitated by cardiac pain, received perhexiline maleate for an average period of 12.2 months. Perhexiline maleate was used either alone or, more commonly, in conjuction with other antianginal therapy, such as beta-adrenergic receptor blocking agents. The results demonstrate that perhexiline maleate is a very effective agent which appears to be safe for long-term usage. Side effects have been frequent, and occasionally bothersome, but all have been transient and dose-dependent. The possibility that the regimens of treatment may materially improve long-term prognosis is raised.

Adrenergic beta-Antagonists↗
PubMed1984

Clinical comparison of midazolam hydrochloride and midazolam maleate for anesthesia induction.

The current study was undertaken to determine whether the same doses (mg/kg) of 5 mg/ml of midazolam hydrochloride and 2.5 mg/ml of midazolam maleate are required for the induction of anesthesia. Midazolam hydrochloride and midazolam maleate were compared in a prospective double-blind fashion, in which both cardiopulmonary and sedative effects were measured in 12 patients who required repeated anesthesia for serial gynecologic radium insertions. The results showed no significant differences in clinical activity between midazolam maleate and the newer preparation, midazolam hydrochloride. Time of onset, recovery time, lack of venous irritation, and stability of cardiopulmonary variables when using the hydrochloride were essentially the same with the maleate.

Adult↗
PubMed1984

The pharmacokinetics and bioavailability of nomifensine maleate in healthy men.

Two studies were conducted in normal male volunteers to establish the pharmacokinetic parameters for nomifensine maleate and to determine the bioavailability of the drug from the Merital capsule intended for U.S. marketing. Single oral doses of 25, 100, and 200 mg of nomifensine maleate as aqueous solutions were administered to 24 men in the open-label Latin-square design pharmacokinetic study. In the bioavailability study, 24 men received single oral 50 mg doses of nomifensine maleate in a capsule or as an aqueous solution. Plasma levels of nomifensine were determined by radioimmunoassay and urinary levels of total nomifensine and its metabolites were assayed by thin-layer chromatography. There was a proportional increase in the area under the curve (AUC) with increasing dose, while peak plasma levels and amounts of total nomifensine and its metabolites excreted in the urine rose as dose increased. The pharmacokinetics of nomifensine are considered linear over the dose range tested. Nomifensine maleate was equally bioavailable from the 50 mg aqueous solution and the Merital capsule formulation.

Administration, Oral↗
PubMedDate not supplied

Disposition of [14C]velnacrine maleate in rats, dogs, and humans.

This study describes the disposition of [14C]velnacrine maleate in rats, dogs, and humans, and the isolation and identification of metabolites in dog urine. Following oral administration of [14C]velnacrine maleate, drug-related material was well absorbed in all three species, with the majority of the dose recovered in the urine. Fecal elimination of radioactivity accounted for the remainder of the dose. The majority of the radioactivity was eliminated within 24 hr. Pharmacokinetic parameters for the elimination of radioactivity from the plasma of rats and dogs were similar after oral dosing compared with intravenous dosing. In humans, the plasma and urinary levels of velnacrine maleate were substantially lower, and the elimination half-life shorter than for total radioactivity, indicating the presence of one or more metabolites with a longer half-life than the parent compound. Preliminary TLC analysis of urine, plasma, and feces showed that metabolism appeared to be similar in the three species investigated. Velnacrine maleate was extensively metabolized with only approximately 10%, 19%, and 33% of the dose appearing in the urine as unchanged drug in humans, dogs, and rats, respectively. Isolation and identification of dog urinary metabolites was conducted. The identity of the isolated metabolites was determined by GC/MS and proton NMR. One of the main metabolic routes was found to be via hydroxylation of the tetrahydroaminoacridine ring with other minor hydroxylated and dihydroxylated metabolites being detected. In addition two dihydrodiol metabolites were also identified. Phase II metabolism did not appear to be a significant route.

Administration, Oral↗
PubMed1978

Maleate induced change in the kidney binding of mercury in rats pretreated with cadmium.

The kidney uptake of Hg2+ was increased by Cd2+-pretreatment when Hg2+ was given intraperitoneally but not subcutaneously. Subsequent s.c. administration of maleate increased Hg2+ release from the kidneys only if Hg2+ was given subcutaneously. Neither the effect of Cd2+, nor that of maleate, on the distribution of Hg2+ among the renal soluble protein fractions was affected by the route of Hg2+ administration. The protective effect of Cd2+-pretreatment against the nephrotoxic effect of Hg2+ was also independent of the route of Hg2+ administration. Maleate given in nephrotoxic doses removed Hg2+ and copper, but not Cd2+ from the renal metallothionein fraction. Mercury in the urine, however, was not complexed by proteins with the molecular weight of thionein, but was bound to high molecular weight proteins and diffusible molecules. These findings are discussed in relation to the role of metallothionein in the interaction between Cd2+ and Hg2+.

Animals↗
PubMed1982

Effect of maleate on membrane physical state of brush border and basolateral membranes of the dog kidney.

The effects of maleate on the physical state of isolated brush border and basolateral membranes from dog kidney cortex have been studied by fluorescence polarization and ESR methods. Anisotropy of 1,6-diphenyl-1.3.5.-hexatriene and hyperfine splitting (2T parallel) of 5-doxylstearic acid in brush border and basolateral membranes were not significantly modified by the addition of 10(-2) M maleate after 60-90 min treatment. These findings further support the view that maleic acid nephropathy is not due to a direct effect of maleate on tubular membranes per se.

Animals↗
PubMed1983

Effects of diethyl maleate on protein synthesis in isolated hepatocytes.

Diethyl maleate is commonly used in toxicological and drug metabolism research using isolated adult rat hepatocytes. At the highest concentrations used the effect of diethyl maleate is, however, not limited to glutathione depletion. In these conditions it inhibits protein synthesis and it impairs the "L" system for amino acid transport. It has, however, no effect on the cytochrome P-450 content or its dependent aldrin monooxygenase. The present report shows that a concentration of diethyl maleate as low as 0.2 mM is sufficient to deplete glutathione without affecting glycogen and protein synthesis, transport of amino acid or monooxygenase activity in isolated adult rat hepatocytes.

Animals↗
PubMed1996

Repeated injections of dizocilpine maleate (MK-801) do not suppress the effects of nigrostriatal dopamine deafferentation on glutamate decarboxylase (GAD67) mRNA expression in the adult rat striatum.

The present study examined the effects of glutamate transmission blockade through N-methyl-D-aspartate (NMDA) receptor subtype by repeated administration of dizocilpine maleate (0.2 mg/kg. i.p., twice a day for eight days) alone or in combination with unilateral 6-hydroxydopamine-induced lesion of the nigrostriatal dopaminergic pathway on GABAergic neurons in the adult rat striatum. For this purpose, the expression of the messenger RNA encoding for the 67 kDa isoform of the GABA synthesizing enzyme, glutamate decarboxylase (GAD67 mRNA), was studied in the various conditions by quantitative in situ hybridization. The dizocilpine maleate treatment alone did not induce significant change of GAD67 mRNA levels in the striatum, indicating that NMDA receptors may not have a major role in the transcriptional regulation of GAD67 in the adult rat striatum. As reported previously, the unilateral dopaminergic lesion resulted in marked increases in GAD67 mRNA levels in the ipsilateral striatum. This up-regulation was not significantly affected by the treatment with dizocilpine maleate started 12 days after the unilateral intranigral 6-hydroxydopamine injection. Therefore, NMDA receptors are unlikely to contribute to the dopamine lesion-induced GAD67 mRNA up-regulation in striatal projection neurons. This result is of major interest in comparison with our previous finding that NMDA receptor activation is necessary to maintain the up-regulation of enkephalin expression in the striatum after dopamine lesion.

Animals↗