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At least 883 records · Page 49Linked to original sources
PubMed1999

A-Current down-modulated by sigma receptor in frog pituitary melanotrope cells through a G protein-dependent pathway.

Gramicidin perforated patch-clamp recordings were used to study the effects of two sigma 1 receptor ligands, (+)-N-cyclopropylmethyl-N-methyl-1, 4-diphenyl-1-ethyl-but-3-en-1-ylamine hydrochloride (JO 1784) and (+)-pentazocine, on the transient outward potassium current (IA) in cultured frog melanotrope cells. (+)-Pentazocine reversibly decreased the current amplitude in a dose-dependent manner. The effects of (+)-pentazocine were mimicked by JO 1784 and were markedly reduced by the sigma 1 receptor antagonist, N, N-dipropyl-2-[4-methoxy-3-2(2-phenylethoxy)phenyl]-ethylamine monohydrochloride (NE 100). Inactivation rate of IA was best fitted with a double exponential function, yielding time constants of 23.7 and 112.5 ms. (+)-Pentazocine (20 microM) accelerated the current decay, decreasing the time constants to 10.7 and 59 ms, respectively. Current-voltage experiments revealed that (+)-pentazocine (20 microM) did neither modify the open-state I/V curves nor the voltage dependence of IA. However, (+)-pentazocine (20 microM) shifted the steady-state inactivation curve toward more negative potentials and increased the time constant of the time-dependent removal of inactivation. In whole-cell experiments, internal dialysis of guanosine-5'-O-(3-thiophosphate) (100 microM) irreversibly prolonged the response to (+)-pentazocine. In addition, cholera toxin pretreatment (1 microgram. ml-1; 12 h) suppressed the inhibition of IA by (+)-pentazocine (20 microM). It is concluded that in frog melanotrope cells, a cholera toxin-sensitive, G protein-dependent inhibition of IA through a sigma 1 receptor activation, at least partially, underlies the excitatory effect of sigma ligands.

Animals↗
PubMed1976

Biological activities of a new specific stimulant of histamine H2 receptors.

Compound N-methyl-2-(5-methyl-4-imidazolyl)ethylamine (5-methyl-N-methylhistamine) was submitted to a thorough pharmacological examination and was found to be a potent stimulant of H2 receptors, devoid of any appreciable effect on H1 receptors. Because of its high degree of specificity it therefore seems to represent an interesting drug to be used in clinical gastric secretory tests and an useful tool for the study of histamine H2 receptors.

Animals↗
PubMed1978

Quantitative structure-activity relationships in the 2,4,5-ring substituted phenylisopropylamines.

The potency of a series of 2,4,5-ring substituted phenylisopropylamines was examined using the rabbit hyperthermia assay. An excellent correlation (r = 0.99) was found between the rabbit hyperthermic and human psychotomimetic potencies. In the hyperthermic model, the 4-X-substituted-2,5-dimethoxyphenylisopropylamines were found to be one to two orders of magnitude more potent than the 2-X- or 5-X-substituted positional isomers (X = -H, -CH3, -SCH3, -Br). Conformational perturbations induced by substituents ortho to the ethylamine side chain were studied with the PCILO and ab initio molecular orbital methods. The variations in the biological activities could not be rationalized in terms of the ability of the ortho substituents to stabilize conformations which mimic LSD. The electronic structures of the positional isomers were examined in the corresponding toluene analogues using the CNDO/2 method. A reasonable correlation (r = 0.98) was found between the Highest Occupied Molecular Orbital (HOMO) energy and the ionization potentials reported from photoelectron spectroscopy studies. In the case of the positional isomers, the HOMO energies were ordered as follows: 4-X greater than 5-X greater than 2-X. However, the regression analysis of the relationship between these orbital energies and Log Biological Activity (B.A.) was not impressive. Examination of the partition coefficients (octanol/water) of the positional isomers indicated that the 4-X- and 5-X-substituted compounds have almost equivalent Log P's, but that the 2-X-substituted-4,5-dimethoxyphenylisopropylamines are unusually hydrophilic. The regression of Log H.P. to the HOMO energies resulted in a marginally significant relationship; addition of the Log P's resulted in no significant improvement. Qualitative models based on both regiospecific lipophilicity or electron densities and also metabolic conversion to reactive intermediates are presented.

Animals↗
PubMed2000

A novel chiral stationary phase in HPLC: optical resolution of racemic amino compounds by (1-->6)-2,5-anhydro-3,4-di-O-ethyl-D-glucitol bound on silica gel.

[(1-->6)-2,5-Anhydro-3,4-di-O-ethyl-D-glucitol]-bound silica gel (CSP 4a), which was prepared by a two-step reaction, was used as a chiral stationary phase in high-performance liquid chromatography. The chiral recognition ability of the CSP 4a for racemates was examined using aq. NaClO4 (pH 2) and aq. NaClO4 (pH 2)/CH3CN as the eluents. For the resolution of amino acids and amino acid methyl esters, the D-isomers were eluted first. The separation factors of many of the racemates were 1.1-1.4, and the resolution factors were 0.59-7.75. This stationary phase showed a relatively high-resolving power toward compounds having a bulky substituent on the chiral carbon, such as phenylglycine and 1-(1-naphthyl)ethylamine.

Journal Article↗
PubMedDate not supplied

[Serotonin metabolism in acute renal ischemia in rabbits].

In tissue of ischemic kidney of rabbits a 5-hydroxytryptophan decarboxylase activity was decreased at first 15 min of ischemia; in contralateral kidney it was slightly increased. Then, within all the studied periods (24 hrs), activity of the enzyme was gradually decreased in both kidneys. The monoamine oxidase activity (substrates serotonin and p-nitrophenyl ethylamine) changed alternatively in early periods of ischemia; it tended to increase, especially in contralateral kidney, within 3 hrs after constriction of kidney artery.

Acute Disease↗
PubMed2001

[Isochromanes related to fluoxetine].

The structure of fluoxetin (1) led to the substituted 3'-phenyl-1'-isochromanyl-2-ethylamines 4-9. These are synthesized by ring closure of the 1,2-diphenylethanols 2a-c with 3-chloropropanal-diethylacetal/BF3-etherate and reaction of the chlorides 3a-c with amines. The affinities to the 5-HT2A-receptor and the serotonin transporter are tested.

Carrier Proteins↗
PubMed2001

[Degradation of methamidophos by Saccharomyces rouxii WY-3].

A strain of Yeast WY-3 was isolated from wastewater sample. It is capable of utilizing methamidophos as sole nitrogen and phosphorus sources, and also capable of utilizing methylamine, ethylamine and ammonium sulfate as nitrogen sources except nitrate and hydroxylamine. The yeast could grow in medinm containing 60% glucose and was identified as Saccharomyces rouxii WY-3. The strain contains a high active acid phosphatase. The crude enzyme was applied to a plate of polyacrylanide gel for electrophoresis, then activity was detected as white single band. Inhibiting test showed that sodium fluoride could seriously inhibit the activity of acid phosphatase to release phosphorus from methamidophos, wherease it make no effect on deamination of the strain WY-3 from methamidophos. After methamidophos was degraded by strain WY-3, toxity of the pesiticide reduced obviously, and its portion intermediate, methanol and inorganic phosphorus, were deteted.

Biodegradation, Environmental↗
PubMed2002

A study on the separation of synthetic pyrethroid stereoisomers by HPLC.

Enantiomer separation of synthetic pyrethroids was carried out on different chiral HPLC columns. In particular, the study provided useful information on the direct resolution of pyrethroids with and without alpha-ciano groups. The study indicated that polymeric chiral stationary phases based on cellulose derivatives are the most appropriate for the stereoisomer separation of cis-Biphenthrin, Resmethrin and (1R)-Phenothrin, whereas multiple-interaction CSPs, like (S)-1-(alpha-naphthyl)-ethylamine/(S)-tert-leucine, are more selective for Cyfluthrin.

Chromatography, High Pressure Liquid↗
PubMed1975

Synthesis and adrenergic neuron blocking properties of some alkylating analogues of bretylium.

A series of ortho-substituted N-alkyl-N-(2-chloroethyl)-benzylamines have been prepared. These compounds are structurally similar to the adrenergic neuron blocking agent bretylium. They were tested for neuron blocking activity using both the innervated rabbit jejunum and the vas-deferens-hypogastric nerve preparation of the guinea pig. Three compounds possessed some adrenergic neuron blocking activity of a prolonged nature, the most potent being N-(2-chloroethyl)-N-(0-bromobenzyl)-ethylamine.

Alkylating Agents↗
PubMed1975

Distribution of [14C]-tofenacine in rat brain after intravenous, intraperitoneal and multiple oral dosage.

The distribution of radioactivity in the rat brain at 5 min after 10 mg/kg of 14C-labelled N-methyl-2[(o-methyl-a-phenylbenzyl)oxy]ethylamine, [14C]-tofenacine-hydrochloride, the active constituent of Elamol¿ and Tofacine¿, i.v. showed a heterogeneous pattern correlating well with what is known about perfusion and capillarization of brain areas. With the passage of time total brain radioactivity decreased rapidly and radioactivity was redistributed. Both processes occurred simultaneously so that a nearly homogeneous pattern was found at 1 h after i.v. administration. The outer layers of the hippocampus were then the only brain areas with a higher concentration of radioactivity. On i.p. administration of 25 mg/kg of [14C]-tofenacine-hydrochloride maximum brain radioactivity was observed at 30 min, the distribution pattern resembling that seen at 5 min after i.v. dosage. Its further time course corresponded to that of the i.v. series. On multiple oral administration of [14C]-tofenacine-hydrochloride (4 doses of 25 mg/kg at 3-h intervals), maximal radioactivity in the rat brain was observed at 120 min after the last dose. Again the distribution was heterogeneous. Areas of high and low radioactivity were very similar to those seen in the i.v. series at the first intervals, although the contrasts were less pronounced. An exception was the hippocampus where the distribution of radioactivity, -- with high levels in the outer layers as the principal feature -- was similar to that at the last intervals after i.v. administration. A model comprising a central compartment and two brain compartments, representing areas of high and low perfusion, respectively, allows a quantitative explanation of the phenomena observed.

Administration, Oral↗
PubMed1976

Identification and specific blockade of two receptors for histamine in the cardiovascular system.

Histamine caused a fall in blood pressure in anesthetized dogs and cats which was only partially attenuated by mepyramine (pyrilamine), a histamine type H1-receptor antagonist. Further treatment with burimide or metiamide, type H2-receptor antagonists, caused nearly complete attenuation of the response to histamine. Burimamide alone had no effect on vasodilatation produced by histamine in the dog gracilis muscle whereas mepyramine alone caused a partial attenuation. An H2-receptor agonist, 4-methylhistamine and an H1-receptor agonist, 2-(2-pyridyl)ethylamine, both produced vasodilatation which was blocked by metiamide and mepyramine, respectively. Constriction of the saphenous vein produced by histamine was found to involve interaction with H1-receptors only. In the intact dog, histamine increased heart rate and decreased left ventricular dp/dt through direct effects. Mepyramine prevented the increase in heart rate but did not affect the chronotropic actions of isoproterenol and glyceryl trinitrate. H1-receptor blockade did not alter inotropic effects whereas subsequent H2-receptor blockade prevented the negative inotropic effect of histamine. It is concluded that both peripheral vascular and cardiac responses to histamine are mediated through activation of H1- and H2-histamine receptors.

Animals↗
PubMed2002

[Study on adhesion of platelets to surface of copoly(benzyl glutamate-hydroxy ethyl glutamine)].

Copoly (benzyl glutamate-hydroxy ethyl glutamine) were prepared by partially aminolysis of poly benzyl glutamate with hydroxyl ethylamine at 60 degrees C for predeternined period. As aminolysis was proceeding, the content of hydroxy ethyl glutamine in copolymer increased and the yield of aminolysis decreased. When aminolysis time reached 16.5 hours, a copolymer with 0.357 mole fraction of hydroxy ethyl glutamine was obtained. After 16.5 hours a soluble yellow viscous product of reaction was obtained. The aminolysized specimens displayed more swelling degree in water, that is, more hydrophilits. The meassurement of solid-liquid contact angles showed that an increase in critical surface tention with content of hydroxy ethyl glutamine in copolymer was observed. Likewise a obvious increase in polar component and a slight decrease in dispersive of surface free energy, thus an increase in total surface free energy with content of hydroxy ethyl glutamine was found. The platelet adhesion and deformation test indicated that less platelets were adhered to surfaces of all aminolysized specimens than that of both poly benzyl glutamate and polydimethylsilicone. The least adhered platelets on surface of copolymer with 0.133 mole fraction of content of hydroxy ethyl glutamine were observed. The partiall aminolysis of poly benzyl glutamate films is an effective method to improve its hydrophility and antithrombogenicity.

Animals↗
PubMed1976

Histamine receptors in esophageal smooth muscle of the opossum.

Esophageal smooth muscle was examined for histamine receptors. The effects of histamine, the histamine analogs 4-methylhistamine (4-MH) and 2-(2-pyridyl) ethylamine (PEA), the histamine receptor antagonists mepyramine and metiamide, and the histamine-releasing substance compound 48/80, on lower esophageal sphincter (LES) and esophageal body (EB) smooth muscle of the opossum were studied in a superfused tissue bath. Histamine, PEA, an H1 receptor agonist, and compound 48/80 caused a dose-related increase in LES basal tension and in EB off response amplitude, the threshold for histamine being 6.7 X 10(-8) M and that for PEA being 6.7 X 10(-7) M. In the presence of mepyramine, and H1 receptor antagonist, the effects of histamine and compound 48/80 were reversed to inhibition of both LES basal tension and EB off response amplitude, while the effect of PEA was abolished. Metiamide, an H2 receptor antagonist, did not alter responses to histamine, PEA, or compound 48/80. The H2 receptor agonist 4-methylhistamine caused a reduction of LES tension and EB off response amplitude, but caused an increase in those parameters in the presence of metiamide. A combination of mepyramine and metiamide abolished responses to all agonist drugs. The results indicate that LES and EB smooth muscle contain both excitatory H1 and inhibitory H2 receptors for histamine. Endogenous histamine released from storage sites in LES and EB and exogenous histamine both preferentially activate H1 receptors.

Animals↗
PubMed2003

Sigma 1 receptor-related neuroactive steroids modulate cocaine-induced reward.

The sigma1 receptor is critically involved in the rewarding effect of cocaine, as measured using the conditioned place preference (CPP) procedure in mice. Neuroactive steroids exert rapid neuromodulatory effects in the brain by interacting with GABA(A), NMDA, and sigma1 receptors. At the sigma1 receptor level, 3beta-hydroxy-5-androsten-17-one [dehydroepiandrosterone (DHEA)] and 3beta-hydroxy-5-pregnen-20-one (pregnenolone) act as agonists, whereas 4-pregnene-3,20-dione (progesterone) is an efficient antagonist. The present study sought to investigate the action of neuroactive steroids in acquisition of cocaine-induced CPP in C57BL/6 mice. None of these steroids induced CPP alone. However, pretreatment with DHEA or pregnenolone (5-20 mg/kg, s.c.) during conditioning with cocaine (10 mg/kg, i.p.) increased the conditioned score. On the contrary, pretreatment with either progesterone (10 or 20 mg/kg, s.c.) or finasteride (25 mg/kg, twice a day), a 5alpha-reductase inhibitor, blocked acquisition of cocaine (20 mg/kg)-induced CPP. A crossed pharmacology was observed between steroids and sigma1 ligands. The sigma1 antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine blocked cocaine-induced CPP and its potentiation by DHEA or pregnenolone. Progesterone blocked cocaine-induced CPP and its potentiation by the sigma1 agonist igmesine. These results showed that neuroactive steroids play a role in cocaine-induced appetence, through their interaction with the sigma1 receptor. Therefore, neuroendocrine control of cocaine addiction may not involve solely glucocorticoids. The importance of neuroactive steroids as factors of individual vulnerability to drug addiction should, thus, be considered.

Animals↗
PubMedDate not supplied

Stereo- and enantioselective determination of pesticides in soil by using achiral and chiral liquid chromatography in combination with matrix solid-phase dispersion.

The separation of enantiomers and diastereomers of 8 commonly used pesticides was investigated by liquid chromatography (LC) using a Chiralcel OD column (cellulose tris-3,5-dimethylphenylcarbamate as the chiral stationary phase) and a Pirkle-type Chirex 3020 column (urea derivative from the reaction of (R)-1-(alpha-naphthyl)ethylamine with (S)-tert-leucine, chemically bonded to 3-aminopropylsilanized silica as the chiral stationary phase). The pesticides studied included one organophosphorus insecticide (phenthoate), 3 triazole fungicides (uniconazole, diniconazole, and propiconazole), and 4 pyrethroids (fenpropathrin, beta-cypermethrin, beta-cyfluthrin, and alpha-fenvalerate). The enantiomers were separated within 20 min with a resolution of > or = 1.5 using a mixture of n-hexane and 2-propanol as the mobile phase for all the pesticides studied except propiconazole, for which only the 2 diastereomers were baseline separated. This method allows determination of the enantiomers or stereoisomers of the above pesticides in soil. The strategy was as follows: (1) First, the total concentration(s) of the enantiomer pair(s) of a chiral pesticide in soil was (were) determined by a newly developed matrix solid-phase dispersion (MSPD) procedure, followed by silica-based LC quantification. The recoveries ranged from 76.5 to 93.6% with relative standard deviations of 6.0%. (2) Second, the enantiomeric ratio(s) (ER(s)) of the chiral pesticide was (were) determined by LC with a chiral stationary phase after fractionation of the MSPD extract by silica-based LC. The determined ERs or stereoisomeric ratio(s) (SR(s); for propiconazole, only the SR of the 2 diastereomers was determined) in soil samples spiked with the above 8 racemic pesticides agreed with those of the corresponding standard solutions. (3) Third, based on the total concentrations and the corresponding ERs, the concentration of each enantiomer in soil was calculated. The proposed method is rapid, precise, and sensitive, and is appropriate for the investigation of the stereo- and enantioselective degradation of pesticides in environmental media.

Chromatography, Liquid↗
PubMed2002

[Study on adductive reaction of Ni[(C4H9O)2PS2]2 with nitrogen base by spectrophotometric method(II)].

Reaction of Ni[(C4H9O)2PS2]2 with ethylamine, n-propylamine, n-butylamine, and n-amylamine have been studied by spectrophotometry in ethanol at 30 degrees C. For nitrogen base(B), the adduct formation of NiL2.B and NiL2.B2 is established, and their additive equilibrium constants (lg beta n) and molecular number (n) have been discussed. All the NiL2.B and NiL2.B2 complexes exhibit virtually the same electronic spectra arising from the five-coordinate NiNS4 and six-coordinate NiN2S4 chromophore respectively. The constants (lg beta n) increase with basicity (pKa) of nitrogen base and can be described by experimental formulas: lg beta 1 = -9.69 +1.15 pKa; lg beta 2 = -18.73 +2.28 pKa.

English Abstract↗
PubMed1992

[NMR spectroscopy of selegiline and related compounds].

In the course of the 1H NMR investigation of Selegiline and compounds related to it, the 3J coupling constants of the protons of the alpha and the beta carbon of the beta-phenyl-ethylamine moiety were determined. The rotameric population around the single bond of the alpha and beta carbons were calculated from these values. It is discussed how substituents at the alpha-carbon atom, at the nitrogen atom and on the phenyl ring as well as the solvent influence the conformational equilibria. The optical purity of the samples were determined using chiral europium shift reagents, however different reagents have to be used for primary, secondary and tertiary amine derivatives. The coordination process between p-F-amphetamine and Eu(tcf)3 was studied in detail, the formation constant of the complex and the bound shifts were determined.

Hydrogen↗
PubMed2004

[Hygienic standards of the occupational air quality established by the Experts on Chemical Agents, 2002].

In 2002, it was necessary to harmonize Polish law on admissible limits of occupational exposure with EU requirements. To this end, the Expert Group on Chemical Agents proposed maximum admissible concentration values for 29 chemicals: acrylaldehyde (107-02-8); cresols, mix of isomers (95-48-7), 108-39-4, 106-44-5, 1319-77-3); tetraphosphorus decaoxide (1314-56-3); ethylamine (75-04-7); naphtalene (91-20-3); nitrobenzene (98-95-3); nitrogen oxide (110-54-5); nitrogen dioxide (10102-44-0); pyridine (110-86-1); butan-2-one (78-93-3); carbon oxide (630-08-0); 1,4-dichlorobenzene (106-46-7); 1,2-dichlorobenzene (95-50-1); hexane (110-54-5); aluminum hydroxide (21645-51-2); aluminum (fumes and dusts) (7429-90-5); amitrole (61-82-5); 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) (80-05-7); 3a,4,7,7a-terahydro-4,7-metanoindene (dicyclopentadiene) (77-73-6); trimethoxyphosphane (121-45-9); methyl chloroacetate (96-34-4); 4-methoxyphenol (150-76-5); methyl formate (107-31-3); 2-phenoxyethanol (122-99-6); divinylbenzene (1321-74-0); Diesel exhausts (-); hexane-6-lactam (dusts and fumes) (105-60-2); 2-isopropoxyethanol (109-59-1); and methyl 2-cyanoacrylate (137-05-3).

Air Pollutants, Occupational↗