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At least 649 records · Page 36Linked to original sources
PubMed1998

Effect of tachykinin receptor antagonists in experimental neuropathic pain.

The intrathecal effect of 0.1 to 10 microg of RP-67,580 (3aR,7aR)-7,7-diphenyl-2[1-imino-2(2-methoxyphenyl)-ethyl]++ +perhydroisoindol-4-one hydrochloride, CP-96,345 (2S,3S)-cis-(2(diphenylmethyl)-N-[(2-methoxyphenyl) methyl]-1-azabicyclo[2.2.2]octan-3-amine), SR-140,333 (S)-(1-¿2-[3-(3,4-dichlorophenyl)- 1-(3-isopropoxyphenylacetyl)piperidin-3-yl]ethyl¿-4-phenyl-1 -azonia-bicyclo[2.2.2.]-octane,chloride), all neurokinin (NK)1-receptor antagonists, SR-48,968 (S)-N-methyl-N[4-(4-acetylamino-4-[phenylpiperidino)-2-(3,4-dichlorophen yl)-butyl]benzamide, a tachykinin NK2 receptor antagonist and SR-142,801 (S)-(N)-(1-(3-(1-benzoyl-3-(3,4-dichlorophenyl) piperidin-3-yl)propyl)-4-phenylpiperidin-4-yl)-N-methyl acetamide, a tachykinin NK3 receptor antagonist, and of their respective inactive enantiomers on thresholds of vocalization due to a mechanical stimulus in mononeuropathic (sciatic nerve ligature) and diabetic rats, was examined. The tachykinin NK1 and the NK2 receptor antagonists were antinociceptive in both models, with a higher effect of the former in diabetic rats. The tachykinin NK3 receptor antagonist was weakly effective in diabetic rats only. This indicates a differential involvement of the tachykinins according to the model of neuropathic pain, suggesting a potential role for tachykinin receptor antagonists in the treatment of neuropathic pain.

Analgesics↗
PubMed1998

Synthesis and pharmacological evaluation of a new class of bicyclic phospholipids, designed as platelet activating factor antagonists.

(+/-)-3-Alkoxymethyl-(2-oxabicyclo[3.3.0]octane)-5-yl-methyl-phosp horyl- ethyl-pyridinium [alkyl chain = methyl (5a) and (5b), allyl (6a) and (6b), n-propyl (7a) and (7b) and n-hexyl (8a) and (8b)] derivatives, structurally designed as conformationally restricted platelet activating factor (PAF) antagonists were synthesized in 12-26% overall yield, using ethyl (+/-)-3-hydroxymethyl-5-(2-oxabicyclo [3.3.0] octane) carboxylate (13a,b) as key intermediate. The anti-platelet profile of the new derivatives was evaluated in a PAF-induced aggregation model in rabbit platelet-rich plasma; only compound 8a exhibited a modest activity.

Animals↗
PubMedDate not supplied

Phacoemulsification of dislocated lens and suture fixation of intraocular lens using a perfluorocarbon liquid.

The objective was to describe a new surgical technique to manage a posteriorly dislocated crystalline lens. Four patients with posteriorly dislocated lenses were studied. Two patients had dislocated lenses secondary to trauma, 1 had undergone retinal detachment surgery, and 1 had an idiopathic lens dislocation. Pars plana vitrectomy was carried out on all 4 eyes, followed by an injection of perfluoro-n-octane to float the lens off the retina. The lens was phacoemulsified through a limbal incision, and an intraocular lens was positioned in the ciliary sulcus with suture fixation. Perfluoro-n-octane was replaced by a balanced salt solution. Postoperative visual acuity ranged from 1.0-1.5. Transient choroidal detachment and hypotony were observed in 3 eyes in the early postoperative period. Postoperative ocular hypertension was noted in 2 eyes and was well-controlled with topical antiglaucoma agent. These results indicate that limbal lensectomy of a posteriorly dislocated lens using perfluorocarbon liquids is a beneficial and relatively safe method.

Fluorocarbons↗
PubMed2002

Use of inverse gas chromatography to determine thermodynamic parameters of aroma-starch interactions.

Interactions between aroma compounds (d-limonene, ethyl hexanoate, octanal and 1-hexanol) and high amylose cornstarch were studied using inverse gas chromatography. Free energies of adsorption (deltaGa) and enthalpies of adsorption (deltaHa) of aroma compounds on starch were measured in the temperature range of 33-40 degrees C. The results showed existence of interactions between aroma compounds and starch, involving hydrogen bounds and dipole-dipole interactions. Sorption isotherms and Henry's law solubility coefficients (S) were determined at 40 degrees C. Three different shapes of isotherms were obtained according to the BET classification: type III for d-limonene, type II for ethyl hexanoate and linear for octanal and 1-hexanol.

Adsorption↗
PubMed2003

Identification of aroma active compounds in orange essence oil using gas chromatography-olfactometry and gas chromatography-mass spectrometry.

Using GC-MS and GC-flame ionization detection (FID)/olfactometry, 95 volatile components were detected in orange essence oil, of which 55 were aroma active. In terms of FID peak area the most abundant compounds were: limonene, 94.5%; myrcene, 1%; valencene, 0.8%; linalool, 0.7%, and octanal, decanal, and ethyl butyrate, 0.3% each. One hundred percent of the aroma activity was generated by slightly more than 4% of the total volatiles. The most intense aromas were produced by octanal, wine lactone, linalool, decanal, beta-ionone, citronellal, and beta-sinensal. Potent aroma components reported for the first time in orange essence oil include: E-2-octenal, 1-octen-3-ol, Z-4-decenal, E,E-2,4-nonadienal, guaiacol, gamma-octalactone, and m-cresol. Over 20 compounds were identified for the first time in orange essence oil using MS, however, most did not exhibit aroma activity.

Citrus↗
PubMed2002

Immunosuppressive constituents from Saussurea medusa.

The methanol extract of Saussurea medusa Maxim afforded two lignans: 2alpha-guaicyl-4-oxo-6alpha-catechyl-3,7-dioxabicyclo [3.3.0]octane and 1alpha-hydroxy-2alpha,4alpha-guaicyl-3,7-dioxabicyclo[3.3.0]octane; two chlorophyll derivatives: 13-epi-phaeophorbide-a and 13-epi-phaeophorbide-a methyl ester; one megastigmane derivative: 3beta-hydroxy-5alpha,6alpha-epoxy-7-megastigmen-9-one, along with 19 known compounds. Their structures were established on the basis of spectroscopic studies.

Bridged Bicyclo Compounds, Heterocyclic↗
PubMed2002

Effects of aldehydes and methods of cross-linking on properties of calcium alginate microspheres prepared by emulsification.

Calcium alginate microspheres were prepared by an emulsification method and cross-linked with various aldehydes using different methods. Methanal and pentanedial produced low aggregation of microspheres while octanal and octadecanal produced the opposite effect. The latter two aldehydes displaced very little calcium ions from the alginate microspheres, indicating that the aggregation was due to the tackiness imparted by the aldehydes to the microsphere surface. Higuchi's model was not applicable to the drug release from microspheres in this study. The microspheres treated with methanal or pentanedial showed comparable dissolution T75% values which were significantly higher than that of the control. In contrast, octanal and octadecanal produced microspheres with lower dissolution T75% values. The drug contents of the microspheres treated with aldehydes were significantly lower than that of the control. There was insignificant interaction between the aldehydes and the drug. However, the aldehydes were found to impart acidity to the aqueous solution to varying extents, resulting in varying drug loss from the microspheres. The properties of the microspheres were also markedly affected by the method of incorporating the aldehyde. Soaking the microspheres in methanal solution produced microspheres with marked aggregation and low drug content.

Aldehydes↗
PubMed1995

Erbium:YAG laser surgery of the vitreous and retina.

PURPOSE: These studies evaluated an erbium:YAG laser for transection of vitreous membranes, retinotomy, and incision and ablation of epiretinal membranes. METHODS: Elevated vitreous membranes, detachments, and epiretinal membranes were induced in rabbit eyes. An erbium:YAG laser, emitting at a wavelength of 2.94 microns and equipped with a flexible fiber and endoprobes with tips ranging from 75 to 375 microns, was used to perform vitreous membrane transections, retinotomies, and epiretinal membrane incisions and ablations in nontransmitting aqueous media with the endoprobe in proximity to the tissue. Ablations of epiretinal membranes also were performed in transmitting media, including air and perfluoro-N-octane with the endoprobe elevated above the membrane. RESULTS: Twenty-five vitreous membrane transections were made in 16 eyes at distances ranging from 0.5 to 4.5 mm from the retina with radiant exposures ranging from 2 to 50 J/cm2 with nonhemorrhagic retinal damage in a single transection. Sharp, linear retinotomies were created successfully in five eyes. Epiretinal membrane ablations were performed with radiant exposures ranging from 1.8 to 22.6 J/cm2. In aqueous media, results of microscopic examination showed partial- to full-thickness ablation with a maximum lateral thermal damage of 50 microns. In air- and perfluoro-N-octane-filled eyes, there was increased lateral damage with desiccation of residual tissue. In 12 aqueous-filled eyes, 18 linear incisions were successfully performed, with retinal nonhemorrhagic damage in 2 eyes and hemorrhage in 5. CONCLUSION: The erbium:YAG laser may provide new approaches to maneuvers performed in vitreoretinal surgery.

Animals↗
PubMed2003

Biodegradation of petroleum hydrocarbon vapors: laboratory studies on rates and kinetics in unsaturated alluvial sand.

Predictions of natural attenuation of volatile organic compounds (VOCs) in the unsaturated zone rely critically on information about microbial biodegradation kinetics. This study aims at determining kinetic rate laws for the aerobic biodegradation of a mixture of 12 volatile petroleum hydrocarbons and methyl tert-butyl ether (MTBE) in unsaturated alluvial sand. Laboratory column and batch experiments were performed at room temperature under aerobic conditions, and a reactive transport model for VOC vapors in soil gas coupled to Monod-type degradation kinetics was used for data interpretation. In the column experiment, an acclimatization of 23 days took place before steady-state diffusive vapor transport through the horizontal column was achieved. Monod kinetic parameters Ks and vmax could be derived from the concentration profiles of toluene, m-xylene, n-octane, and n-hexane, because substrate saturation was approached with these compounds under the experimental conditions. The removal of cyclic alkanes, isooctane, and 1,2,4-trimethylbenzene followed first-order kinetics over the whole concentration range applied. MTBE, n-pentane, and chlorofluorocarbons (CFCs) were not visibly degraded. Batch experiments suggested first-order disappearance rate laws for all VOCs except n-octane, which decreased following zero-order kinetics in live batch experiments. For many compounds including MTBE, disappearance rates in abiotic batch experiments were as high as in live batches indicating sorption. It was concluded that the column approach is preferable for determining biodegradation rate parameters to be used in risk assessment models.

Biodegradation, Environmental↗
PubMed2000

Noncompetitive antagonist-binding sites of rat and housefly gamma-aminobutyric acid receptors display different enantiospecificities for tert-butyl(isopropyl)bicyclophosphorothionate.

The enantiomers of 4-tert-butyl-3-isopropyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2 ]octane 1-sulfide (TBIPPS) were prepared in nine steps from diethyl tert-butylmalonate, and their abilities to compete with [3H]1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2 ]octane (EBOB), a noncompetitive antagonist of ionotropic gamma-aminobutyric acid (GABA) receptors, at their binding site were investigated using rat brain and housefly head membranes. The (S)-(-)-isomer of TBIPPS (IC50 = 398 nM) was more potent than was the (R)-(+)-isomer of TBIPPS (IC50 = 1220 nM) in rat receptors, while the potencies of (S)-TBIPPS 104 nM) and (R)-TBIPPS (IC50 = 94.4 nM) in housefly receptors were almost the same. The different enantiospecificities of rat and housefly receptors indicate that the three-dimensional structure of the binding site might be different between these receptors. In a region of the rat binding site there might be a steric bulk that interacts less favorably with (R)-TBIPPS than with (S)-TBIPPS, while in the corresponding region of the housefly binding site there might not be such a steric bulk that leads to specificity for these compounds.

Animals↗
PubMed2002

Determination of the ground state, excited state and change in dipole moments of magnesium and zinc chlorin.

High-resolution Stark effect measurements on the S1 <-- S0 (pi pi*) origin of magnesium chlorin (MgCh) and zinc chlorin (ZnCh) in single crystals of n-octane at 4.2 K are reported. The corresponding change in dipole moment (absolute value(delta mu(ge))) associated with each transition was estimated to be 0.23 +/- 0.04 and 0.27 +/- 0.05 debye, respectively. Each molecule's orientation in the n-octane crystal was also determined. The change in dipole moment of MgCh was also found using solvatochromic shift data (absolute value(delta mu(ge))) = 0.33 +/- 0.08 debye). The ground state dipole moment (mu(g)) of MgCh was determined by dielectric constant measurement of MgCh/benzene solutions (mu(g) = 2.26 +/- 0.08 debye). These were combined to calculate the average excited state dipole moment of MgCh (mu(e) = 2.51 +/- 0.08 debye). The ground state dipole moment of ZnCh was also determined using solvatochromic shift data (mu(g) = 3.17 +/- 0.08 debye). This was combined with its measured absolute value(delta mu(ge)) to calculate the excited state dipole moment of ZnCh (mu(e) = 3.44 +/- 0.08 debye); the S1 <-- S0 (pi pi*) origin band of both complexes was red-shifted at room temperature as the polarity of the solvents was increased, which implies that delta mu(ge) is positive.

Electrochemistry↗
PubMed2000

Purification and characterization of organic solvent-stable lipase from organic solvent-tolerant Pseudomonas aeruginosa LST-03.

An organic solvent-stable lipase (LST-03 lipase) secreted into the culture broth of the organic solvent-tolerant Pseudomonas aeruginosa LST-03 was purified by ion-exchange and hydrophobic interaction chromatography in the presence of 2-propanol. The purified enzyme was homogeneous as determined by SDS-PAGE. The molecular mass of the lipase was estimated to be 27.1 kDa by SDS-PAGE and 36 kDa by gel filtration. The optimum pH and temperature were 6.0 and 37 degrees C. LST-03 lipase was stable at pH 5-8 and below 40 degrees C. Its hydrolytic activity was highest against tricaproin (C6), methyl octanoate (C8), and coconut oil respectively among the triacylglycerols, fatty acid methyl esters, and natural oils investigated. The enzyme cleaved not only the 1,3-positioned ester bonds, but also the 2-positioned ester bond of triolein. It exhibited high levels of activity in the presence of n-decane, n-octane, DMSO, and DMF as well as in the absence of an organic solvent. In addition, LST-03 lipase was stabler in the presence of n-decane, ethyleneglycol, DMSO, n-octane, n-heptane, isooctane, and cyclohexane than in the absence of an organic solvent.

Journal Article↗
PubMed2003

Monolayer-protected gold nanoparticles as a stationary phase for open tubular gas chromatography.

The use of a thin film of monolayer-protected gold nanoparticles (MPNs) as a stationary phase for gas chromatography (GC) is reported. Deposition of a MPN film was obtained in a 2-m, 530-microm-i.d. deactivated silica capillary using gravity to force the solution containing the MPN material through the capillary. By SEM analysis, the average film thickness was determined to be 60.7 nm. The retention behavior for the dodecanethiol MPN column was studied using four compound classes (alkanes, alcohols, aromatics, ketones), and retention orders were objectively compared to a commercially available column (AT-1, 100-nm film thickness). Separation of an eight-component mixture was performed using both isothermal and temperature-programming methods with the dodecanethiol MPN phase and compared to an isothermal separation with the AT-1 phase. The AT-1 phase separation had an efficiency, N, of 6200 (k' = 0.33) while the dodecanethiol MPN phase separation had an efficiency, N, of 5700 (k' = 0.21) for the same analyte, octane. The reduced plate height, h, for octane was found to be less than 1 at the optimum linear flow velocity, indicating the MPN column operated near the optimum possible performance level. Robustness of the MPN phase is also discussed with consistent performance observed over several months. Overall, MPNs appear promising as a stationary-phase material for GC and as an experimental platform to study their thermodynamic and mass-transfer properties.

Journal Article↗
PubMed2005

Analysis of derivatized biogenic aldehydes by LC tandem mass spectrometry.

Lipid peroxidation has been linked to the etiology of several diseases, including Alzheimer's disease (AD). End products of this phenomenon include low molecular weight, water-soluble aldehydes, compounds that covalently modify proteins and nucleic acids, thereby altering function. Aliphatic aldehydes (C3-C10) are generated during lipid peroxidation, along with alpha,beta-unsaturated aldehydes, including acrolein and 4-hydroxynonenal (HNE). The Hantzsch reaction was used to produce heterocyclic aldehyde derivatives that can be conveniently analyzed with mass spectrometry. Liquid chromatographic analyses revealed increasing retention times from derivatized methanal to octanal. HNE derivatives were observed to elute between heptanal and octanal derivatives, while the acrolein derivatives had a retention time similar to the propanal derivative. Smaller aliphatic aldehyde derivatives fragmented in a similar manner to produce a base peak of m/z 273, while the larger derivatives yielded m/z 274 as the base peak. Acrolein and HNE derivatives fragmented in a slightly different manner compared to their aliphatic counterparts. Calibration plots of aliphatic and unsaturated aldehydes were linear (r2 >/= 0.99) in the concentration range explored (approximately 5-1500 pg on column). The LC-MS/MS methodology developed here will be used in subsequent studies to determine aldehyde concentrations for comparing age-matched controls to AD tissues from human subjects.

Acrolein↗
PubMed2005

Spraying enzymes in microemulsions of AOT in nonpolar organic solvents for fabrication of enzyme electrodes.

A new technique suitable for automated, large-scale fabrication of enzyme electrodes by air-spraying enzymes in organic inks is presented. Model oxidoreductases, tyrosinase (Tyr) and glucose oxidase (GOx), were adapted to octane-based ink by entrapment in a system of reverse micelles (RM) of surfactant AOT in octane to separate and stabilize the catalytically active forms of the enzymes in nonpolar organic media. Nonpolar caoutchouk polymer was also used to create a kind of "dry micelles" at the electrode/solution interface. Enzyme/RM/polymer-containing organic inks were air-brushed onto conductive supports and were subsequently covered by sprayed Nafion membranes. The air-brushed enzyme electrodes exhibited relevant bioelectrocatalytic activity toward catechol and glucose, with a linear detection range of 0.1-100 microM catechol and 0.5-7 mM glucose; the sensitivities were 2.41 A M(-1) cm(-2) and 2.98 mA M(-1) cm(-2) for Tyr and GOx electrodes, respectively. The proposed technique of air-brushing enzymes in organic inks enables automated construction of disposable enzyme electrodes of various designs on a mass-production scale.

Biosensing Techniques↗
PubMed2007

Structural characterization of a beta-diketone hydrolase from the cyanobacterium Anabaena sp. PCC 7120 in native and product-bound forms, a coenzyme A-independent member of the crotonase suprafamily.

The gene alr4455 from the well-studied cyanobacterium Anabaena sp. PCC 7120 encodes a crotonase orthologue that displays beta-diketone hydrolase activity. Anabaena beta-diketone hydrolase (ABDH), in common with 6-oxocamphor hydrolase (OCH) from Rhodococcus sp. NCIMB 9784, catalyzes the desymmetrization of bicyclo[2.2.2]octane-2,6-dione to yield [(S)-3-oxocyclohexyl]acetic acid, a reaction unusual among the crotonase superfamily as the substrate is not an acyl-CoA thioester. The structure of ABDH has been determined to a resolution of 1.5 A in both native and ligand-bound forms. ABDH forms a hexamer similar to OCH and features one active site per enzyme monomer. The arrangement of side chains in the active site indicates that while the catalytic chemistry may be conserved in OCH orthologues, the structural determinants of substrate specificity are different. In the active site of ligand-bound forms that had been cocrystallized with the bicyclic diketone substrate bicyclo[2.2.2]octane-2,6-dione was found the product of the asymmetric enzymatic retro-Claisen reaction [(S)-3-oxocyclohexyl]acetic acid. The structures of ABDH in both native and ligand-bound forms reveal further details about structural variation and modes of coenzyme A-independent activity within the crotonases and provide further evidence of a wider suprafamily of enzymes that have recruited the crotonase fold for the catalysis of reactions other than those regularly attributed to canonical superfamily members.

Amino Acid Sequence↗
PubMedDate not supplied

Two- and three dimensional combinatorial chemistry from multicomponent Grignard reagents.

The conjugate addition of five component Grignard reagents to methyl ecgonidine was used to create libraries of 3-substituted tropanes. By variation in the reagent combination in 10 such 5-membered sublibraries, a library of 25 compounds was made in a two-dimensional format. Screening of this library led to identification of two new potent monoamine transporter ligands that were subsequently synthesized. The most potent compound in this library was (1R,2S,3S,5S)-3-(3,4-dimethylphenyl)-8-methyl-8-azabicyclo[3.2.1]octane-2-carboxylic acid methyl ester, which inhibited dopamine transporter (hDAT) binding and reuptake with a K(i) of 26 and 20 nM, respectively. The conjugate addition to a 5-membered library of methyl ecgonidine analogues with variation of nitrogen substituent was also carried out and used to create 15 sublibraries of 25 compounds, which displayed 125 compounds in a three-dimensional format. From this 3D library, several potent dopamine transport inhibitors were likewise identified and synthesized. The most potent hDAT inhibitor discovered was (1R,2S,3S,5S)-3-(3,4-dimethylphenyl)-8-pentyl-8-azabicyclo[3.2.1]octane-2-carboxylic acid methyl ester. The study also showed that 3-alkyltropanes were poor inhibitors of monoamine transporters.

Alcohols↗