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PubMed1997

Experimental studies with perfluoro-octane for hemostasis during vitreoretinal surgery.

PURPOSE: To investigate the effect of perfluoro-octane on coagulation studies and on intraoperative hemostasis during vitreoretinal surgery in an animal model. METHODS: In vitro study--comparison of coagulation profiles (bleeding time, whole blood clotting time, partial thromboplastin time, and one-stage prothrombin time) of blood taken from healthy volunteers with and without the addition of perfluoro-octane. In vivo study--comparison of times taken to achieve hemostasis in a rabbit model with large retinal arterial bleeding in vitrectomized and aphakic eyes with and without intraocular injection of perfluoro-octane. RESULTS: In vitro study--perfluoro-octane had no significant effect on coagulation profiles. In vivo study--intraocular perfluoro-octane significantly reduced the time to achieve hemostasis (P < 0.01) at all infusion bottle heights in vitrectomized and aphakic rabbit eyes. CONCLUSIONS: Perfluoro-octane may be used to control bleeding during vitreoretinal surgery. A direct effect on the clotting cascade could not be demonstrated.

Adult↗
PubMed1977

A study on the distribution of methylchloroform and n-octane in the mouse during and after inhalation.

The distribution of methylchloroform and n-octane, respectively, in the blood, liver, kidney, and brain of mice was studied at different inspired air concentrations and after different exposure times. The air concentration varied between 10 and 10,000 ppm; and the exposure time, between 0.5 and 24 h. The resulting solvent concentrations in kidney and brain were about the same, but the liver concentrations were usually somewhat higher for both solvents. There was a linear dependence between inspired air concentration and tissue concentrations at fixed exposure times. A correlation between blood and organ concentrations was observed in animals exposed at different inhalation air concentrations but not in animals exposed only at one fixed concentration. The ratios between the concentrations of the solvents in the organs and blood were higher for n-octane than for methylchloroform. The ratios increased as the exposure concentration increased for all organs studied in the case of n-octane but only for the liver in the case of methylchloroform. When the exposure dose, i.e., inspired air concentration X time, was generated in different ways, a high concentration during a short exposure resulted in a ten times higher organ concentration than a low concentration during a long exposure. The liver, kidney, and brain concentrations generally did not differ more than twice between methylchloroform and n-octane after exposure of the same concentration and duration. The blood concentration, however, was much less in n-octane exposed animals than in methylchloroform exposed ones. A pharmacokinetic model with both uptake and elimination of the first order fitted the empirical data better for methylchloroform than a model with zero order uptake and first order elimination. Postexposure concentrations of methylchloroform were linear in a semilog graph. A one-compartment pharmacokinetic model was in accordance with the experimental data for methylchloroform. For n-octane, however, at least a two-compartment model must be assumed.

Aerosols↗
PubMed2004

New 4-aminobicyclo[2.2.2]octane derivatives and their activities against Plasmodium falciparum and Trypanosoma b. rhodesiense.

A series of new 2-substituted 4-dialkylaminobicyclo[2.2.2]octane derivatives was prepared and the compounds were investigated for their activity against causative organisms of tropical diseases. The tests were performed as microplate assays using the K1 strain of Plasmodium falciparum (resistant to chloroquine and pyrimethamine) and Trypanosoma brucei rhodesiense (STIB 900). The results were compared to the activities of former tested compounds of the bicyclo[2.2.2]octane series and to known drugs. Most of the 4-amino-6,7-diphenylbicyclo[2.2.2]octan-2-one thiosemicarbazones were compounds with attractive antimalarial potency (IC(50)=0.84-0.99microM, chloroquine: IC(50)=0.12microM). One of the bicyclo[2.2.2]octan-2-yl 4-tert-butylbenzenesulfonates showed the highest antitrypanosomal activity (IC(50)=0.68microM) of the so far prepared 4-amino-6,7-diarylbicyclo[2.2.2]octane derivatives, but is distinctly less active than suramin (IC(50)=0.0075microM).

Animals↗
PubMed1982

Metabolism in the rat of potassium DL-octan-2-sulphate, a secondary alkyl sulphate.

1. The metabolism of potassium [2-14C]octan-2-sulphate and potassium octan-2-[35S]sulphate was investigated in the rat. Following oral administration, the bulk of the radioactivity was eliminated in the urine within 24 h. 2. Whole-body radioautography showed the liver to be the principal site of tissue accumulation of radiolabel following administration of 14C- or 35S-labelled DL-octan-2-sulphate. 3. Octan-2-sulphate was extensively degraded in vivo. The major urinary components are five sulphate estes, present in urine in essentially the same proportions regardless of label. The relative proportions of radioactivity associated with the urinary components showed considerable differences between male and female rats. 4. Three of the components have been identified as butanoate-3-sulphate, hexanoate-5-sulphate and octanoate-7-sulphate. The remaining metabolite was tentatively identified as an aldehyde derivative of octan-2-sulphate, a possible intermediate in the formation of octanoate-7-sulphate.

Animals↗
PubMed1975

An examination of octanol and octanal metabolism to octanoic acid by horse liver alcohol dehydrogenase.

The kinetics of the horse liver alcohol dehydrogenase (alcohol: NAD+ oxidoreductase EC 1.1.1.1) catalyzed metabolism of octanol and octanal to octanoic acid have been examined. On incubation of octanol with horse liver alcohol dehydrogenase in the presence of NAD+, NADH as well as octanal and octanoic acid were seen as the initial products. However, on continued incubation, the octanal concentration progressively decreased to where only negligible quantities were present in the incubation after 10 min. The production of NADH was biphasic. An initial phase was followed in about 2 min with a slower but linear rate of NADH production. The production of octanoic acid was approximately linear throughout the 10 min incubation period. Since octanal is an intermediate in the oxidation of octanol to octanoic acid, the ability of semicarbazide to inhibit the metabolism of octanol to octanoic acid was examined. At a concentration of semicarbazide which was 63 times the concentration of octanol in the incubation media, the rate of formation of octanoic acid was inhibited by only 30%. The results of these experiments suggest that in the oxidation of octanol to octanoic acid a portion of the octanal formed from octanol is not released from the enzyme but, in the presence of NAD+, is oxidized to octanoic acid.

Alcohol Oxidoreductases↗
PubMed1996

Corner Bromination of 2-Methyl-endo-tricyclo[3.2.1.0(2,4)]octane and -oct-6-ene.

Reaction of 2-methyl-endo-tricyclo[3.2.1.0(2,4)]octane (1) with bromine in CCl(4) gave 2-exo,3-endo-dibromo-2-endo-methylbicyclo[3.2.1]octane (3) which rearranges on silica to 2-exo,6-endo-dibromo-1-methylbicyclo[2.2.2]octane (4). Reaction in methanol gave 4-endo-bromo-2-exo-methoxy-2-endo-methylbicyclo[3.2.1]octane (10) and 4-endo-bromo-2-endo-methoxy-2-exo-methylbicyclo[3.2.1]octane (11) formed by corner attack of the bromine electrophile with C2-C4 bond rupture and inversion of configuration at the site of electrophilic attack. Reaction of 2-methyl-endo-tricyclo[3.2.1.0(2,4)]oct-6-ene (2) with bromine in CCl(4) and methanol gave products of reaction at the alkene site.

Journal Article↗
PubMed1996

A Tandem Horner-Emmons Olefination-Conjugate Addition Approach to the Synthesis of 1,5-Disubstituted-6-azabicyclo[3.2.1]octanes Based on the AE Ring Structure of the Norditerpenoid Alkaloid Methyllycaconitine.

A novel Horner-Emmons olefination conjugate addition reaction of N-acetylamides to form 1,5-disubstituted-6-azabicyclo[3.2.1]octanes with two bridgehead quarternary carbon centers is reported. This reaction is a key step in an approach to the synthesis of small ring analogues based on the AE ring structure of the Delphinium norditerpenoid, methyllycaconitine (MLA) (1). Initially, 3-(hydroxymethyl)cyclohex-2-en-1-one (10) was selected as the starting material to these structures, but its generation proved inefficient. In contrast, the synthesis of 3-[(phenylthio)methyl]cyclohex-2-en-1-one (6) and 3-(1,3-dithian-2-yl)cyclohex-2-en-1-one (11) proceeded in good yield. Subsequent hydrocyanation, ketalization, reduction, acetylation, deprotection of the acetal, and Horner-Emmons olefination-conjugate addition reaction to form 1-[(phenylthio)methyl]-5-[(ethoxycarbonyl)methyl]-6-acetamido-6-azabicyclo[3.2.1]octane (28), 1-(1,3-dithian-2-yl)-5-[(ethoxycarbonyl)methyl]-6-acetyl-6-azabicyclo[3.2.1]octane (29), respectively, are reported, as well as for readily available 3-methylcyclohex-2-en-1-one (12). Studies on the Pummerer rearrangement of 28 and subsequent desulfurization and reduction to form an hydroxymethyl-substituted azabicyclo[3.2.1.]octane (40) and then selective protection to form a protected hydroxyethyl N-ethyl (hydroxymethyl)azabicyclo[3.2.1]octane (3) are also described.

Journal Article↗
PubMed2002

Elusive 6-exo-Hydroxybicyclo[2.2.2]octan-2-ones from the corresponding acetates by methanolysis in the presence of CH(3)ONa/La(OTf)(3).

[reaction: see text] A series of 6-exo-acetoxybicyclo[2.2.2]octan-2-ones were converted into the corresponding 6-exo-hydroxybicyclo[2.2.2]octan-2-ones by methanolysis in the presence of CH(3)ONa/La(OTf)(3). Under the given conditions, epimerization at C(6) of the latter led in the least favorable cases only to traces of the more stable 6-endo-hydroxybicyclo[2.2.2]octan-2-ones. This procedure, when combined with the described conversion of easily available 6-endo-hydroxybicyclo[2.2.2]octan-2-ones into the corresponding 6-exo-acetoxy derivatives, provides a convenient route to elusive 6-exo-hydroxybicyclo[2.2.2]octan-2-ones. Applications to total synthesis are shown and envisaged.

Journal Article↗
PubMed2002

Molecular dynamics simulations of conformational behavior of linear RGD peptidomimetics and cyclic prodrugs in aqueous and octane solutions.

Conformations available to a class of cyclic prodrugs and corresponding linear RGD peptidomimetics were explored using 1 ns length molecular dynamics simulations performed with the program CHARMM. Water and octane, modeled explicitly, were used as solvents to mimic the change of the environment experienced by the solutes upon partition from water to membrane in the trans-cellular transport process. In water, the linear peptidomimetics tended to populate extended-like structures, characterized by strong favorable interactions with solvent and low intrinsic stability. In these extended conformations the charged termini are able to assume large distances, above 15 A for the longest systems. These linear peptidomimetics have been found to exhibit the highest potency in experimental studies, in accord with the trends experimentally observed for RGD peptides. In contrast, in octane compact conformers of the linear peptidomimetics were favored, with all charged groups aggregated and shielded from solvent, exhibiting high intrinsic stability and weak solute-solvent interactions. Our calculations predict a large unfavorable energy change for transferring the linear systems from water to octane, in agreement with experimental findings that these compounds are not transported via the trans-cellular pathway. The cyclic prodrugs did not exhibit major structural differences between the simulations in water and octane, adopting turn-like conformations in both solvents. The limited response of the cyclic structures to changes in the environment leads to energies of transfer from water to octane that are also unfavorable, but much less so than for the linear molecules. This effect is in accord with the observed enhanced passive trans-cellular transport of the cyclic prodrugs.

Amino Acid Sequence↗
PubMed2005

Synthesis of 2-azabicyclo[3.2.2]nonanes from bicyclo[2.2.2]octan-2-ones and their activities against Trypanosoma brucei rhodesiense and Plasmodium falciparum K1.

PURPOSE: New 2-azabicyclo[3.2.2]nonanes were prepared from antiprotozoal bicyclo[2.2.2]octan-2-ones to investigate the influence of the replacement of the rigid bicyclo-octane structure by the more flexible bicyclo-nonane system on the antiplasmodial and antitrypanosomal activity. METHODS: The 2-azabicyclo[3.2.2]nonanes were synthesized via a one-step procedure from bicyclo[2.2.2]octan-2-ones and tested for their activities against Trypanosoma b. rhodesiense and Plasmodium falciparum K1 (resistant to chloroquine and pyrimethamine) using in vitro microplate assays. RESULTS: 2-azabicyclo[3.2.2]non-5-ylamines exhibit higher antiprotozoal activities than 4-aminobicyclo[2.2.2]octanes, 4-aminobicycl [2.2.2]octan-2-ones and 4-amino-2-azabicyclo[3.2.2]nonan-3-ones. (7, 8-Diphenyl-2-azabicyclo[3.2.2]non-5-yl)-dimethylamine shows enhanced anti-trypanosomal (IC50 = 0.60 microM) and remarkable antiplasmodial (IC50 = 0.28 microM) activity. However, the in vivo activity of this compound against Plasmodium berghei in mice is moderate. CONCLUSIONS: Due to their promising in vitro antiprotozoal activity and their low cytotoxicity, 2-azabicyclo[3.2.2]nonanes should serve as lead compounds for further modifications.

Animals↗
PubMed1978

[Bicyclic piperazine homologues XIV (1). Synthesis and analgesic activity of 3,8-diaza-bicyclo[3.2.1.] octane derivatives].

The synthesis of two new series of 3,8-diazabicyclo [3.2.1] octane derivatives is described. The first series includes some 3-(or 8)-allyl and 3-(or 8)-(3,3-dimethylallyl) derivatives of 3,8-diazabicyclo [3.2.1] octane and 3,8-diazabicyclo [3.2.1] octane-2-one. The second series includes some esters and carbamates of 3-(3-hydroxy-3-methyl)butyl-3,8-diazabicyclo [3.2.1] octane. Two new 3,8-diazabicyclo [3.2.1] octane derivatives structurally related to propoxyphene are also described. Some pharmacological data of these compounds are reported.

Analgesics↗
PubMed1990

Intrinsic isotope effects suggest that the reaction coordinate symmetry for the cytochrome P-450 catalyzed hydroxylation of octane is isozyme independent.

The mechanism of the omega-hydroxylation of octane by three catalytically distinct, purified forms of cytochrome P-450, namely, P-450b, P-450c, and P-450LM2, was investigated by using deuterium isotope effects. The deuterium isotope effects associated with the omega-hydroxylation of octane-1,1,1-2H3, octane-1,8-2H2, and octane-1,1,8,8-2H4 by all three isozymes were determined. From these data the intrinsic isotope effects were calculated and separated into their primary and secondary components. The primary intrinsic isotope effect for the reaction ranged from 7.69 to 9.18 while the secondary intrinsic isotope effect ranged from 1.13 to 1.25. Neither the primary nor secondary isotope effect values were statistically different for any of the isozymes investigated. These data are consistent with a symmetrical transition state for a mechanism involving initial hydrogen atom abstraction followed by hydroxyl radical recombination which is essentially independent of the specific isozyme catalyzing the reaction. It is concluded that (1) in general the porphyrin-[FeO]3+ complex behaves as a source of a triplet-like oxygen atom, (2) the regioselectivity for the site of oxidation is dictated by the apoprotein of the specific isozyme of cytochrome P-450 catalyzing the reaction, and (3) the maximum primary intrinsic isotope effect for any cytochrome P-450 catalyzed oxidation of a carbon center is about 9, assuming no tunneling effects.

Cytochrome P-450 Enzyme System↗
PubMed1995

Growth on octane alters the membrane lipid fatty acids of Pseudomonas oleovorans due to the induction of alkB and synthesis of octanol.

Growth of Pseudomonas oleovorans GPo1, which contains the OCT plasmid, on octane results in changes in the membrane phospholipid fatty acid composition. These changes were not found for GPo12, an OCT-plasmid-cured variant of GPo1, during growth in the presence or absence of octane, implying the involvement of OCT-plasmid-encoded functions. When recombinant strain GPo12(pGEc47) carrying the alk genes from the OCT plasmid was grown on octane, the cells showed the same changes in fatty acid composition as those found for GPo1, indicating that such changes result from induction and expression of the alk genes. This finding was corroborated by inducing GPo12(pGEc47) with dicyclopropylketone (DCPK), a gratuitous inducer of the alk genes. Further experiments showed that the increase of the mean acyl chain length of fatty acids is related to the expression of alkB, which encodes a major integral membrane protein, while the formation of trans unsaturated fatty acids mainly results from the effects of 1-octanol, an octane oxidation product.

1-Octanol↗
PubMed1998

Biotransformation of octane by E. coli HB101[pGEc47] on defined medium: octanoate production and product inhibition.

E. coli HB101[pGEc47], which is able to convert octane to octanoate, but cannot oxidize octanoate further, was grown on defined medium with glucose as carbon source in batch and continuous culture. The biomass yield on glucose decreased from 0.32 +/- 0.02 g g-1 in aqueous cultivations to 0.25 +/- 0.02 g g-1 in the presence of octane. Maximal octanoate productivities of 0.6 g L-1 h-1 were the same as found in cultivations on complex medium. The glucose-based carbon recovery in these experiments was 99 +/- 4% (in extreme, between 90% and 105%). An increase of the octane feed from 1% to 2% (v/v) or more led to washout of cells. This effect was reversible when the octane feed was decreased to its initial value of 1%. Analysis of experimental data by model simulation strongly suggested that washout was due to inhibition by octanoate only. Pulses of octanoate to a continuous culture grown on aqueous media were applied to analyze the inhibition further. Inhibition by acetate was not significant, but its presence in the medium reflected a physiological state that made the cells more sensitive to octanoate inhibition. Model simulation with linear inhibition kinetics could perfectly predict glucose consumption and the resulting glucose concentration. The linear type of inhibition was confirmed by a variety of batch experiments in the presence of different concentrations of octanoate. The glucose-based specific growth rate, mu, decreased linearly with increasing concentrations of octanoate and became zero at a threshold concentration pmax of 5.25 +/- 0.25 g L-1.

Bioreactors↗
PubMed1999

[Prediction the octane number of gasoline by near infrared spectra analysis].

The feasibility of predicting the octane number by the near infrared spectra analysis technique in the quantitative analysis was investigated. 12 calibration gasoline samples and 4 prediction samples were collected and their absorption spectra were measured with a high precision model Lambda 19 scanning spectrophotometer. Based on the multivariate statistic model, stagewise regression and partial least squares were selected. A model of the correlation behavior between the spectra and octane number was established and calibrated, and then the prediction of octane number is made. The prediction error is +/-1.0 octane number in the best analysis results.

Gasoline↗
PubMed1983

Studies on the utilization of octane by algae.

The objective of this study was to investigate the influence of various octane concentrations on a mixed culture of Scenedesmus obliquus, Chlorella vulgaris and Oscillatoria sp. and the ability of these algae to utilize octane as the sole source of organic carbon in the medium. The same investigations were carried out for a mixed culture consisting of algae and the strain Acinetobacter calcoaceticus, and for A. calcoaceticus alone. The results obtained show that all of the strains under study, both algal and bacterial, can grow even at high octane concentrations and that they are able to utilize octane.

Acinetobacter↗
PubMed1996

The stability of perfluoro-N-octane during vitreoretinal procedures.

OBJECTIVES: To examine the propensity for intraoperative procedures, such as endolaser, to generate polar impurities in perfluorocarbon liquids, either by degradation of the compound or by dissolution of materials contacting the liquid, given the value of these liquids as adjuncts to vitreoretinal procedures and the importance of using pure and inert liquid. METHODS: Perfluoro-N-octane liquid recovered from patients after vitreoretinal procedures was analyzed by gas chromatography, nuclear magnetic resonance, ultraviolet spectroscopy, and a cell proliferation assay. Similar analyses were performed on pure and impure perfluoro-N-octane exposed in vitro to superclinical energy levels of argon and YAG laser, endodiathermy, and endoillumination. RESULTS: No change in chemical structure and only minor (parts per million) increases in dissolved contaminants were observed. The perfluoro-N-octane liquid retained its inertness as indicated by the inability of fibroblasts to attach and proliferate on its surface. CONCLUSION: The structure and biologic inactivity of perfluoro-N-octane are unaffected by vitreoretinal surgical manipulations.

Adolescent↗
PubMed1995

Single crystal X-ray structures of the two 4-heptadecyl derivatives of (1R,5S)-3,6,8-trioxabicyclo[3.2.1]octane.

The single crystal structures of the two diastereomeric 4-heptadecyl derivatives of (1R,5S)-3,6,8-trioxabicyclo[3.2.1]octane have been determined by X-ray diffraction to be (1R,4R,5S)-heptadecyl-3,6,8-trioxabicyclo[3.2.1]octane (I) and (1R,4S,5S)-4-heptadecyl[3,6,8-trioxabicyclo[3.2.1]octane (II), respectively, which have an exo or axial 4-heptadecyl group, and an endo or equatorial 4-heptadecyl group, respectively. The structures of I and II had been suggested by their phase-sensitive 2D NOESY 1H-NMR spectra, but are now established unambiguously. These optically pure non-ionic lipid-like amphipathic molecules (I and II) represent the first 3,6,8-trioxabicyclo[3.2.1]octanes for which single crystal structures have been solved. Crystals of both isomer I and isomer II were orthorhombic with space group P2(1)2(1)2(1), and had unit cell dimensions of a = 9.586, b = 43.14, c = 5.289 A, and a = 7.34, b = 51.8, c = 5.636 A, respectively. The structures of I and II were both solved by using direct methods to R = 0.045 and R = 0.086, respectively. Both I and II pack in stacked bilayers with interdigitating and tilting hydrocarbon chains. The molecular and hydrocarbon cross sections are I: S = 50.70 A2, sigma = 19.00 A2; and II: S = 41.37 A2, sigma = 18.26 A2.

Bridged Bicyclo Compounds, Heterocyclic↗