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At least 739 records · Page 41Linked to original sources
PubMed1992

Perfluorocarbon liquid effects on corneal endothelial permeability.

We investigated the effects of perfluoro-n-octane liquid on the rabbit corneal endothelial permeability to inulin and dextran. Permeability measurements were made either after 10 minute in vitro exposure of the endothelium to 50 microliters of the test liquid or after one week exposure in vivo following injection of 50 microliters of the test fluid into the anterior chamber. Retention of the perfluorocarbon on the in vitro cornea and in the anterior chamber during the appropriate exposure time was visually verified. The corneal endothelial permeability was unchanged after either short or sub-chronic treatment with perfluoro-n-octane indicating an absence of toxicity for this substance should it reach the cornea either intraoperatively or postoperatively.

Animals↗
PubMed2005

Synthesis and biodistribution of radiolabeled alpha 7 nicotinic acetylcholine receptor ligands.

UNLABELLED: Our objective was to develop an array of alpha(7)-selective nicotinic cholinergic receptor (nAChR)-based imaging agents for PET and SPECT. METHODS: (2'R)-N-(11)C-Methyl-N-(phenylmethyl)-spiro[1-azabicyclo[2.2.2]octane-3,2'(3'H)-furo[2,3-b]pyridin]-5'-amine 1 was synthesized by reaction of the corresponding desmethyl precursor with (11)C-CO(2) and reduction. N-(R)-1-Aza-bicyclo[2.2.2]oct-3-yl-4-(11)C-methylsulfanyl-benzamide 2 was synthesized by reduction of the corresponding disulfide precursor and reaction with (11)C-iodomethane. N-(R)-1-Aza-bicyclo[2.2.2]oct-3-yl-4-(125)I-iodo-benzamide 3 was synthesized by halogen exchange of the corresponding bromide. (2'R)-5'-(2-(125)I-iodo-3-furanyl)spiro[1-azabicyclo[2.2.2]octane]-3,2'(3'H)-furo[2,3-b]pyridine 4 was synthesized by the chloramine-T method. Kinetic biodistribution studies were done in male CD-1 mice by tail vein injection of 3.7 MBq (100 microCi) of the (11)C-labeled radiotracer or 0.67 MBq (2 microCi) of the (125)I-labeled radiotracer followed by brain dissection and tissue counting. Receptor blockade was determined by pretreatment of the mice with an excess of either unlabeled precursor or nicotine. RESULTS: We synthesized 4 radiolabeled, moderate- to high-affinity, alpha(7)-nAChR-based ligands. The compounds were a series of quinuclidine derivatives with an inhibition constant (K(i)) < 6 nmol/L (33 pmol/L for 4) for alpha(7)-nAChR and selectivities of alpha(7)/alpha(4)beta(2) subtypes of > or =14,000. All of the compounds were produced in adequate radiochemical yield and specific radioactivity (>74 GBq/micromol [2,000 Ci/mmol]). No site selectivity or receptor blockade was shown for 1 and 2 (0.91 +/- 0.05 and 0.14 +/- 0.03 %ID/g [percentage injected dose per gram] in the hippocampus [target tissue], respectively). Compound 3 showed low hippocampal uptake (0.25 +/- 0.05 %ID/g) but prolonged retention within that structure. Pretreatment with nicotine decreased its uptake by up to 50% in the hippocampus. Similar reductions were also observed within the cerebellum (nontarget tissue). Compound 4 showed hippocampal uptake of 2.41 +/- 0.03 %ID/g and target-to-nontarget uptake ratios of up to 2. Pretreatment of animals with unlabeled 4 resulted in a decrease of hippocampal uptake to 60% of its preblockade value without a corresponding decrease in cerebellar uptake. CONCLUSION: With further structural optimization, selective imaging of alpha(7)-nAChR may be possible.

Animals↗
PubMed2005

Nematicidal activity and chemical component of Poria cocos.

Poria cocos, a famous traditional Chinese medicine, was found to have nematicidal activity in experiments searching for nematicidal fungi. The experiment showed it could kill 94.9% of the saprophytic nematode, Panagrellus redivivue, 92.6% of the root-knot nematode, Meloidogyne arenaria, and 93.5% of the pine nematode, Bursaphelenchus xylophilus, on PDA plate within 12 hours. According to the nematicidal activity, three new compounds, 2, 4, 6-triacetylenic octane diacid, 2, 4, 5, 6-tetrahydroxyhexanoic acid and 3, 4-dihydroxy-2-keto-n-butyl 2,4,5,6-tetrahydroxyhexanate, were isolated from submerged cultures of Poria cocos. Of these, 2, 4, 6-triacetylenic octane diacid could kill 83.9% Meloidogyne arenaria and 73.4% Panagrellus redivivus at 500 ppm within 12 hours. Here, it is reported for the first time that Poria cocos has nematicidal activity.

Animals↗
PubMed1975

Hydrophobic interaction of alkanes with liposomes and lipoproteins.

Human serum lipoproteins and egg yolk lecithin liposomes are able to solubilize large amounts of n-hexane and n-octane. At the maximum water solubility of n-octane the mole ratio of alkane to lipoprotein was 65 for high density lipoprotein (holo-HDL) and 900 for low density lipoprotein (holo-LDL). Alkane binding to lipid-free apo-HDL is negligible compared to alkane solubility in holo-HDL. Alkane solubility in the lipoproteins and liposomes is thermodynamically consistent with the simple soution of hydrocarbon in the hydrophobic regions of these particles. The unitary free energies of alkane transfer are similar to values previously observed for detergent micelles but are less favorable by 0.8 kcal/mol from the free energy of transfer to liquid hydrocarbon. It is concluded that the thermodynamics of alkane transfer to the lipoproteins resembles that found for detergent micelles or liposomes rather than that anticipated for an "oil drop" (i.e. liquid hydrocarbon).

Alkanes↗
PubMed1990

The use of perfluorocarbon liquids in vitreous surgery.

Perfluoro-octane is used as an intraoperative tool for manipulation of the retina during vitreous surgery for retinal detachment in cases of proliferative vitreoretinopathy (PVR), giant tears and large peripheral retinotomies. One case of a macular hole combined with a peripheral one was also treated in this way. Perfluoro-octane seems, in our experience, a useful instrument for intraoperative atraumatic flattening of the retinal in those complicated cases with largely detached retinas.

Fluorocarbons↗
PubMed1986

Inhibition of Met5-enkephalin-Arg6-Phe7 degradation by inhibitors of dipeptidyl carboxypeptidase.

The heptapeptide Met5-enkephalin-Arg6-Phe7 (YGGFMRF) is cleaved at a high rate by tissue peptidases including dipeptidyl carboxypeptidase. The inhibitor, Hoe 498 diacid (2-[N-[(S)-1-carboxy-3-phenylpropyl]-L-alanyl]-(1S,3S,5S)-2-azabicyclo- [3.3.0] octane-3-carboxylic acid), was found to be highly effective in blocking YGGFMRF degradation by a dipeptidyl carboxypeptidase present in a preparation of mouse striatal microsomes. The recovery of YGGFMRF released from rat striatal slices was increased in the presence of Hoe 498 diacid. Furthermore, the recovery of YGGFMRF injected into the caudate was increased in rats pretreated i.p. with Hoe 498 diacid. After i.v. or i.p. injections both Hoe 498 diacid and its prodrug Hoe 498 monoester (2-[N-[(S)-1-ethoxycarbonyl-3-phenylpropyl]-L-alanyl]-(1S,3S,5S)-2- azabicyclo [3.3.0] octane-3-carboxylic acid) were detected in rat cerebrospinal fluid and the dipeptidyl carboxypeptidase activity in cerebrospinal fluid was inhibited. These observations indicate that endogenously released YGGFMRF is protected from degradation by Hoe 498 diacid and that systemically administered Hoe 498 diacid or monoester penetrate the blood-brain barrier and inhibit brain and cerebrospinal fluid dipeptidyl carboxypeptidase activity. This potent inhibitor may be useful to block YGGFMRF inactivation in studies of the pharmacology and physiology of YGGFMRF. It is also possible that some of the cerebral effects of these compounds may be referable to an enhancement of YGGFMRF action in the central nervous system.

Animals↗
PubMed1988

Na+-independent transport of basic and zwitterionic amino acids in mouse blastocysts by a shared system and by processes which distinguish between these substrates.

Preimplantation mouse blastocysts were found to contain at least three mediated components of Na+-independent amino acid transport. The two less conspicuous components seemed to be selective for either cationic or zwitterionic substrates but were not characterized further or examined for multiple transport activities. L-Leucine and L-lysine competed strongly for uptake by the most conspicuous Na+-independent transport process detected in these conceptuses (referred to as component b0,+), and no further heterogeneity of transport activities was found within this component. A series of inhibitors of various strengths had about the same effect on component b0,+ when either leucine or lysine was the substrate, and uptake of each substrate was not affected significantly by changes in the pH between 6.3 and 8.0. Furthermore, the Ki values for mutually competitive inhibition of transport between leucine and lysine and their Km values for transport via component b0,+ were all on the order of about 100 microM. In addition, the Ki values for competitive inhibition of leucine or lysine uptake by valine were approximately 5 mM in both cases, and alanine appeared to be a similarly weak competitive inhibitor of leucine transport. Based on these results, component b0,+ prefers to interact with bulky amino acids that do not branch at the beta-carbon. Moreover, amino acids that branch at the alpha-carbon, such as the leucine analog 3-amino-endo-bicyclo[3.2.1]octane-3-carboxylic acid, were virtually excluded by this component. The substrate reactivity of component b0,+ is more limited than the Na+-dependent transport system B0,+ in blastocysts which accepts both these branched species and less bulky amino acids relatively well as substrates. Thus, mediated amino acid transport in the mouse trophoblast is clearly distinguishable from that in most other mammalian tissues that have been studied. Not only do component b0,+ and system B0,+ and system B0,+ fail to discriminate strongly between basic and zwitterionic substrates, but their relative reactivity with bicyclic amino acids, such as 3-amino-endo-bicyclo[3.2.1]octane-3-carboxylic acid, is the reverse of transport processes in other cell types where these amino acids react strongly with Na+-independent, but not Na+-dependent, systems.

Alanine↗
PubMed1979

The synthesis of some bridgehead N,O-heterocycles of biological interest.

The preparation of 5-aryl-6-oxa-1-azabicyclo[3,3,0]octanes, 6-aryl-5-oxa-1-azabicyclo[4,3,0]nonanes and 7-aryl-6-oxa-1-azabicyclo[5,3,0]decanes from the corresponding substituted omega-chlorobutyrophenones and aminoalcohols is described; and the ring opening reactions are studied. A preliminary biologic activity study has also been conducted, and demonstrated that the 5-(2,5-dimethyl)phenyl-6-oxa-1-azabicyclo[3,3,0]octane possesses antiinflammatory activity.

Analgesics↗
PubMedDate not supplied

[Stabilization of flat bilayer lipid membranes by cholesterol].

Cholesterol is found to produce a stabilizing effect on bilayer lipid membranes (BLM) from alpha-monoglycerides of fatty acids and n-octan. The greatest stabilization effect is observed for alpha-monoglycerides, in which the length of hydrocarbon radical coincides with the length of cholesterol molecule. The life time of BLM from alpha-monolaurin, cholesterol and n-octan is measured in hours, and the tension of electric damage of the membrane reaches 860 mV.

Alkanes↗
PubMedDate not supplied

[Use of the fluorescence method to detect and quantitatively determine lipids in the cells of microorganisms].

Techniques have been developed for the detection and quantitative determination of lipids in the living cells of microorganisms (after their fixation by heating) using benzimidazole luminophores synthesized by Monocrystalreactive (USSR). When the yeast cells are stained by a luminophore, the latter is selectively bound to cellular lipids producing a brightly fluorescent complex. The intensity of fluorescence increases proportionally to an increase in the concentration of lipids in the microbial mass. The intensity of fluorescence of a microbial suspension is recorded using a spectrofluorimeter at the excitation and fluorescence maxima of 405 and 475 nm respectively. In order to assay the content of lipids in microorganisms which do not produce a homogeneous suspension, the luminophore bound to lipids is extracted from the cells with hot octane. The absolute content of lipids in the biomass is determined using a standard curve which shows the intensity of fluorescence of microorganisms and their octane extracts as a function of the lipid content in the cell.

Ascomycota↗
PubMed1994

Dopamine D1 receptor-stimulated release of acetylcholine in rat striatum is mediated indirectly by activation of striatal neurokinin1 receptors.

Activation of dopamine D1 receptors is thought to stimulate release of striatal acetylcholine (ACh) indirectly, possibly through local release of substance P which, in turn, may enhance release of ACh. To test this hypothesis, in vivo microdialysis was used to assess the effect of neurokinin1 (NK1) receptor blockade on D1 agonist-induced increases in ACh release in the striatum of awake, freely moving rats with and without a unilateral 6-hydroxydopamine-induced lesion of the nigrostriatal pathway. Local perfusion with the D1 agonist (+-)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3- benzazepine-7,8-diol hydrochloride (SKF 38393; 1-25 microM for 20 min) increased striatal ACh release in both intact rats and rats with a 6-hydroxydopamine-induced lesion, although the increase was greater in magnitude in rats with a lesion. Local application of the NK1 antagonist, (2S,3S)-cis-2-(diphenylmethyl)-N- [(methoxyphenyl)methyl]-1-azabicyclo[2.2.2]octan-3-amine (CP-96,345; 10 and 25 microM), but not its less active enantiomer (2R,3R)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)methyl]-1- azabicyclo[2.2.2]octan-3-amine (CP-96,344; 10 and 25 microM), decreased the elevation in ACh induced by SKF 38393 in both intact rats and rats treated with 6-hydroxydopamine. Systemic administration of the NK1 antagonist 17-beta-hydroxy-17-a-androstanol[3.2- b]pyrimidol[1,2-a]benzimidazole hydrochloride (WIN 51,708; 20 mg/kg i.p.) also reduced the increase in ACh release induced by local perfusion of SKF 38393.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1993

[The structure identification of zhepiresionol].

A new 3,7-dioxabicyclo[3, 3, O] octan-6-one named zhepeiresinol was isolated from Fritillaria thumbergii Miq. The spectroscopic and X-ray diffraction analysis established the structure as 2-(3',5'-dimethoxy-4'-hjydroxyphenyl)-3,7-dioxabicyclo[3, 3, O]octan-6-one.

Bridged Bicyclo Compounds↗
PubMed1977

Quantitative analysis of human serum cholesterol by thin-layer chromatographic spot test.

A fast, inexpensive, simple method is described for the determination of the total cholesterol concentration in human serum. The cholesterols (free and esterified) are extracted from serum by a double extraction procedure, using isopropanol-water-10 N sodium hydroxide (250:125:10) and then n-octane. An aliquot of the octane extract is spotted on a thin-layer plate and the cholesterol in the spot is rendered visible using an aqueous phosphomolybdic acid staining solution and a heat treatment for the color development. The colored spot is scanned with a densitometer.

1-Propanol↗
PubMed1995

Paired-ion extraction and high-performance liquid chromatographic determination of diminazene in cattle plasma: a modified method.

The high-performance liquid chromatographic method published by Aliu & Odegaard (1983) was found to give poor peak separation when used to determine plasma diminazene concentrations in cattle. Before bioequivalence studies could be carried out, the method had to be modified. Solid-phase extraction with acetonitrile/0.025 M Na-octane sulphonate and 2% acetic acid as eluent, followed by sample concentration, gave recoveries of > 90% for diminazene and the internal standard. A mobile phase of acetonitrile/0,005 M Na-octane sulphonate, 0.1% triethylamine, pH 3.2 with acetic acid on a Nova Pak C18 column was used for the analysis. Wavelength switching was used to determine the internal standard (imidocarb) and diminazene at their respective wavelengths of maximum absorbance, resulting in a fivefold increase in the limit of detection for diminazene. The modified method attained a detection limit of 2 ng.m.-1 (peak 4x baseline noise), limit of quantitation of 10 ng.m.-1 (coefficient of variation < 15%) and an accuracy of > 96% over the range from 10-5000 ng.m.-1.

Animals↗
PubMed1977

[Inhibition of nonenzymatic ATP hydrolysis by its binding with the cationic detergent micelles].

The rate of ATP hydrolysis is shown to decrease sharply by its binding with mycelles formed from cetyltrimethyl ammonium bromide (CTAB) (pH 9.0, 20 degrees C). Under these conditions only trace amounts of hydrolytic products have been found in the reaction mixture after a two-months standing. In the absence of mycelles the ATP hydrolysis is practically completed in 7 days. The energies of ATP, ADP and Pi binding with mycelles and at the interface of the "octane - water" system with previously adsorbed CTAB have been measured. The estimates demonstrate that the binding of one negative charge of phosphate anion or that of nucleotides with CTAB at the interface of the "octane - water" system corresponds to the change in free energy, i.e. -3.5 ccal/mol. The sharp deceleration of ATP hydrolysis cannot be due to the shift in the equilibrium of ATP hydrolysis reaction towards the formation of the pyrophosphate bond under conditions when all reaction components are bound to the surface of the mycelles.

Adenosine Diphosphate↗
PubMed1977

[Bicyclic analogs of piperazine. XII. (1) - Synthesis of 3,8-diazabicyclo/3,2,1/octanes as potential antiparkinson agents].

As a part of research on 3,8-diazabicyclo [3,2,1] octanes, the Authors report on the synthesis of some amides of methyl, phenyl and cyclohexyltropic acid, potentially active as antiparkinson agents. Also reported is the synthesis of some compounds similar to two known drugs, Caramiphene and Cycrimine. These compounds differ from the said drugs in having a 3,8-diazabicyclo [3,2,1] octane as a basic moiety.

Antiparkinson Agents↗
PubMed1996

Solid-phase extraction and HPLC determination of levamisole hydrochloride in sheep plasma.

The anthelmintic, levamisole, was determined in sheep plasma by means of ion-pair solid-phase extraction (SPE) and reverse-phase liquid chromatography. The SPE columns were conditioned with 2 ml of methanol followed by 1 ml of octane sulphonic-acid buffer. After sample application, the columns were washed with 2 ml of the same buffer, followed by elution with 90/10 acetonitrile:buffer. A phenyl reverse-phase column (Spherisorb S5 Phenyl, 250 x 4.6 mm) was used with a mobile phase of acetonitrile: 0.005 M of octane sulphonic-acid sodium salt and 0.2% triethylamine in water, pH 3.5, 38/62. Extraction recoveries of 89-94% were achieved over the range from 100-3750 ng/ml. Accuracy and precision were better than 96% and 2.6%, respectively, over said range, with a limit of quantitation of 50 ng/ ml.

Animals↗
PubMed1997

CP-96,345, which inhibits [3H] substance P binding, selectively inhibits the behavioral response to intrathecally administered N-methyl-D-aspartate, but not substance P, in the mouse.

((2S,3S)-[cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)-methyl]-1-az abicyclo[2.2.2]octan-3-amine]) (CP-96,345) noncompetitively inhibits substance P (SP) binding at the neurokinin-1 (NK-1) site and has been widely used to determine the extent of NK-1 activity in nociception. To test the selectivity of this compound in vivo regarding other putative nociceptive transmitters, such as excitatory amino acids, we compared the actions of CP-96,345 to those of ((2R,3R)-[cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)-methyl]-1-az abicyclo[2.2.2]octan-3-amine]), a less active isomer, on behavioral responses induced by SP, N-methyl-D-aspartate (NMDA) and kainic acid (KA) injected intrathecally in mice. When injected intrathecally, SP, NMDA or KA produce a caudally directed biting and scratching behavior that lasted for approximately 60 to 90 sec. At a dose as high as 2 nmol, CP-96,345 had no effect on responses induced by a single injection of 22.5 pmol of SP. In contrast, NMDA-induced behaviors were inhibited by CP-96,345 in a dose-related fashion beginning at a dose as low as 0.02 nmol. There was also an inhibitory effect of CP-96,345 on KA-induced activity that was not dose related. The more potent inhibitor of [3H] SP binding, (+)-(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine (CP-99,994), was approximately 10 times more potent in inhibiting NMDA-induced activity than CP-96,345. CP-99,994 also inhibited NMDA-induced activity at doses that failed to inhibit SP-induced behavior. Also attenuated by CP-96,345 was the development of sensitization to the behavioral effects produced by repeated injections of KA and desensitization to repeated injections of SP, phenomena linked to an action of the N-terminus of SP. NMDA-induced behaviors and sensitization to KA were found to be sensitive to verapamil, consistent with their mediation by calcium. These results indicate that either CP-96,345 and CP-99,994 do not inhibit NK-1-induced activity in the mouse spinal cord, or that exogenously administered SP does not induce behavioral responses by an interaction with NK-1 receptors. Whether CP-96,345 acts by a mechanism that involves inhibition of calcium channels and/or SP N-terminal activity requires further testing.

Animals↗