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PubMed1996

Prediction of FCC gasoline octane numbers using FT-MIR and PLS.

A method for predicting "octane numbers" (RON and MON) in fluid catalytic cracking (FCC) gasolines is proposed. Using FT-MIR and PLS, improvements have been obtained in sample throughput, reduced delay times, accuracy (repeatability and reproducibility), amounts of samples and reagents and environmental working conditions when compared with current standard methods. A total number of 140 daily production samples were taken; and from there, a learning group was prepared (44 samples); a validation set (96 samples) was prepared, as well. Sample spectra were recorded from 4000 to 600 cm(-1) at 4 cm(-1) intervals (traditional sealed NaCl cells). The PLS technique was used in its two variants (1 and 2-block). Both provided similar results. Their predictive characteristics are very good: SEP(RON)=0.38; SEP(MON)=0.40; repeatability <0.1 O.N.; reproducibility <0.3 O.N. (SEP=Standard Error of Prediction).

Journal Article↗
PubMed1983

Catalysis by hemoproteins and their structural organization in reversed micelles of surfactants in octane.

The cytochromes P-450 LM-2 and b5 from rabbit liver microsomes have been entrapped into reversed micelles of surfactants in octane. The optimum conditions providing for the maximum stability of the hemoproteins have been found: pH and concentration of the buffer solution, the glycerol addition, the surfactant concentration, the [H2O]/[surfactant] ratio and, finally, the reversed micelles composition including aerosol OT and its mixture with Triton X-45, Tween 20 and cetyltrimethylammonium bromide (CTAB). The transformation kinetics of the hemoproteins solubilized by detergents has been studied by monitoring the absorbance of hemoproteins in the Soret band region. Significant changes in tryptophan fluorescence of cytochrome b5 and in CD spectra of myoglobin in reversed micelles and their dependence on the [H2O]/[aerosol OT] ratio have been shown. The three hemoproteins in reversed micelles have been found to exhibit high catalytic activity with respect to their reaction with cumene hydroperoxide. The kinetic and spectral data reveal the structural transformations of the proteins entrapped into the micelles due to the interactions of the lumenal surface of the micelles and the protein molecule surface.

Aerosols↗
PubMed1993

Artificially glycosylated alpha-chymotrypsin in reversed micelles of Aerosol OT in octane. A new approach to elucidation of the role of carbohydrate moieties in glycoproteins.

A comparative study of native and artificially glycosylated alpha-chymotrypsin in reversed micelles of Aerosol OT in octane was carried out. D-Glucosamine and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide were used as modifying agents to yield glycosylated enzyme. Unlike the native alpha-chymotrypsin, the modified protein tended to form reversible oligomeric structures, revealed by the appearance of an additional maximum (characteristic of dimeric forms of protein functioning) as a result of the enzyme catalytic activity being dependent on the AOT hydration degree. Dependence of the enzyme catalytic activity on the surfactant concentration in the case of the modified enzyme was similar to that of glycoproteins, and suggests its membrane affinity. The role of carbohydrate moieties in the functioning of glycoproteins is discussed.

Animals↗
PubMed1995

Determination of a new fluoroquinolone antimicrobial agent, (S)-10-[(S)-(8-amino-6-azaspiro d3,4]octan-6-yl)]-9-fluoro-2, 3-dihydro-3-methyl-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6- carboxylic acid hemihydrate, DV-7751a, in human serum and urine using solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method for the determination of a new fluoroquinolone antimicrobial agent, (S)-10-[(S)-(8-amino-6-azaspiro[3,4]octan-6-yl)]-9-fluoro-2,3- dihydro-3-methyl-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid hemihydrate (DV-7751a, I) in human serum and urine has been developed. Compound I and the internal standard were extracted from serum and urine by means of Bond Elut C8 LRC column. The extracts were chromatographed on a reversed-phase Inertsil ODS-2 column using tetrahydrofuran-50 mM KH2PO4 (pH2)-1 M ammonium acetate (19:81:1, v/v) as the mobile phase at a flow-rate of 1.0 ml/min. Fluorescence detection at an excitation wavelength of 305 nm and an emission wavelength of 530 nm resulted in a limit of quantitation of 0.0098 microgram/ml for serum and 0.098 microgram/ml for urine. The method showed satisfactory sensitivity, precision, accuracy, recovery and selectivity. Stability studies showed that I was stable in serum and urine for at least 1 month at -20 degrees C and for at least 48 h at room temperature.

Anti-Infective Agents↗
PubMed1993

A potential imaging agent for the GABAA receptor: 4-t-butyl-1-(4-[123I]iodophenyl)-2,6,7-trioxabicyclo-[2.2.2]octane.

Based upon the known high toxicity and high antagonist activity of t-butylorthobenzoates towards the GABA receptor complex, 4-t-butyl-1-(4-iodophenyl)-2,6,7-trioxabicyclo[2.2.2]octane 5 and its radioiodo analogues ([123I]-5 and [131I]-5 were prepared as potential markers for the gated chloride channel of GABAA receptors. Mice showed rapid clearance of [131I]-5 from all organs including the brain. The radioactivity was found to proceed into the urine in spite of the high lipophilicity of 5, the high binding affinity of 5 for plasma protein and the apparent chemical stability of 5 in plasma.

Animals↗
PubMed2006

Synthesis of 8-thiabicyclo[3.2.1]octanes and their binding affinity for the dopamine and serotonin transporters.

Cocaine is a potent stimulant of the central nervous system. Its reinforcing and stimulant properties have been associated with inhibition of the dopamine transporter (DAT) on presynaptic neurons. In the search for medications for cocaine abuse, we have prepared 2-carbomethoxy-3-aryl-8-thiabicyclo[3.2.1]octane analogues of cocaine. We report that this class of compounds provides potent and selective inhibitors of the DAT and SERT. The selectivity resulted from reduced activity at the SERT. The 3beta-(3,4-dichlorophenyl) analogue inhibits the DAT and SERT with a potency of IC(50)=5.7 nM and 8.0 nM, respectively. The 3-(3,4-dichlorophenyl)-2,3-unsaturated analogue inhibits the DAT potently (IC(50)=4.5 nM) and selectively (>800-fold vs SERT). Biological enantioselectivity of DAT inhibition was limited for both the 3-aryl-2,3-unsaturated and the 3alpha-aryl analogues (2-fold), but more robust (>10-fold) for the 3beta-aryl analogues. The (1R)-configuration provided the eutomers.

Animals↗
PubMed2006

The identification of pyrimidine-diazabicyclo[3.3.0]octane derivatives as 5-HT2C receptor agonists.

The 5-HT2C receptor has been implicated in the regulation of appetite. As such, small molecule agonists to this receptor may serve as novel therapies to combat obesity. We describe here the identification, synthesis, and SAR of a 5-HT2C agonist from a unique pyrimidine-diazabicyclo[3.3.0]octane series. This compound displayed good potency at the 5-HT2C receptor, modest selectivity relative to other 5-HT2 receptors, and was efficacious in an acute feeding study in rats.

Amines↗
PubMed2006

Antiprotozoal activities of new bis-chlorophenyl derivatives of bicyclic octanes and aza-nonanes.

The in vitro activity of newly synthesized bis-(chlorophenyl)-azabicyclo[3.2.2]nonanes and bis-(chlorophenyl)-bicyclo[2.2.2]octanes against Plasmodium falciparum K(1) (resistant to chloroquine and pyrimethamine) and Trypanosoma brucei rhodesiense was investigated. Especially the bis-(chlorophenyl)-azabicyclo[3.2.2]nonanes exhibit promising antitrypanosomal activity and were tested in vivo against Trypanosoma brucei brucei featuring moderate activities.

Animals↗
PubMed2006

Antiplasmodial and antitrypanosomal activity of new esters and ethers of 4-dialkylaminobicyclo[2.2.2]octan-2-ols.

Only three drugs are available for the treatment of East African trypanosomiasis. Patients suffer from painful application, severe side effects and increasing resistance against these drugs. Malaria tropica kills more than 2 million people every year mainly due to growing drug resistance. 4-Dialkylaminobicyclo[2.2.2]octan-2-ols and some of their esters have shown activity against both the causative organisms, Trypanosoma brucei rhodesiense and Plasmodium falciparum. Ethers and new esters with markedly higher lipophilicity were prepared in three-step procedures from acyclic synthons. The new compounds were screened for their antiprotozoal activities against T. b. rhodesiense (STIB 900) and P. falciparum K1 (resistant to chloroquine and pyrimethamine), and for their cytotoxicity with L-6 cells by means of in vitro microplate assays. The results were compared to those of the parent compounds indicating that higher lipophilicity increases the antiprotozoal activities. The pivalate 10a showed the highest antitrypanosomal activity. The 4-chlorobenzoate 9b exhibited good antiplasmodial activity and low cytotoxicity. The most active antiplasmodial agent was the benzhydryl ether 13c which was nearly as active as chloroquine against sensitive strains.

Animals↗
PubMed2005

Structure and property studies of hybrid xerogels containing bridged positively charged 1,4-diazoniabicycle[2.2.2]octane dichloride.

The compound di-3-n-propyltrimethoxysilane (1,4-diazoniabicycle[2.2.2]octane) dichloride, [(MeO)3Si(CH2)3N+ (CH2CH2)3N+ (CH2)3Si(OME)3]Cl2 was obtained and was used as a precursor reagent to obtain hybrid xerogels where the organic molecule was bonded to a silica framework by reacting the ends of both sides of the precursor reagent. That is, both -Si(OME)3 groups react with tetraethylorthosilicate (TEOS) by hydrolysis-condensation reactions. The resulting hybrid xerogels with variable C/Si mole ratios were prepared and analyzed and their textural characteristics determined. The samples prepared presented micropores with diameter 1.5 nm, the chain length of which matched with the estimated length of the organic bridging group. The charged organic bridging groups allow the immobilization of hexacyanoferrate ions by an ion exchange process. The electron transfer process of the hexacyanoferrate anionic complex confined in the pores of the matrices was studied by cyclovoltammetry.

Journal Article↗
PubMed2003

Outcomes of surgery for retinal detachment associated with proliferative vitreoretinopathy using perfluoro-n-octane: a multicenter study.

PURPOSE: To report visual acuity and anatomical outcomes, as well as complications, of management of complex retinal detachment with proliferative vitreoretinopathy using pars plana vitrectomy and intraoperative perfluoro-n-octane (PFO), and to investigate clinical features associated with anatomical and visual acuity outcomes. DESIGN: Prospective, noncomparative, interventional multicenter study. METHODS: The study included 555 patients (555 eyes) 15 months of age or older who underwent pars plana vitrectomy for complex retinal detachment associated with proliferative vitreoretinopathy with intraoperative PFO at 24 study sites between April 1994 and February 1996. Main outcome measures included visual acuity and rates of retinal reattachment, reoperation, retained PFO, corneal edema, elevated intraocular pressure ([IOP] > 25 mm Hg), hypotony (IOP < 5 mm Hg), and cataract. All outcome measures were assessed at 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively and at the last examination. RESULTS: The study included 555 eyes of 555 patients followed up at a median of 5.6 months. Visual acuity of 20/200 or better was recorded in 51 (10%) patients preoperatively and 85 (24%) at 6 months postoperatively. Among the 465 eyes with both preoperative and final visual acuities available, postoperative visual acuity improved in 274 (60%) eyes, remained stable in 106 (23%), and worsened in 85 (18%) eyes. Six-month follow-up data were obtained for 356 (65%) eyes; the retina was attached in 279 (78%) eyes and retained PFO was noted in 20 (6%). Throughout follow-up, 238 of 555 (43%) eyes underwent reoperation for recurrent retinal detachment. At 6 months, corneal edema, elevated IOP, and hypotony were noted in 26 of 356 (7%), 6 of 356 (2%), and 48 of 356 (15%) eyes, respectively. Of the 114 phakic eyes without significant cataract preoperatively, 105 (92%) developed a significant cataract or underwent cataract surgery during study follow-up. Operative factors significantly (P <.05) associated with recurrent retinal detachment include female gender, creation of a relaxing retinotomy, and the use of sulfur hexafluoride (SF(6)) gas tamponade, air tamponade, or no tamponade (compared with perfluoropropane [C(3)F(8)] or silicone oil tamponade). Factors significantly associated with final vision of 20/200 or better include first operation anatomic success, prior scleral buckling procedure, no diabetes mellitus, no prior vitrectomy, no silicone oil retinal tamponade, and no relaxing retinotomy. Cases that require relaxing retinotomy generally represent more severe cases of complex retinal detachment and, therefore, relaxing retinotomy is likely associated with a poorer visual outcome owing to the nature of the cases selected for this procedure. CONCLUSIONS: In the management of complex retinal detachment associated with proliferative vitreoretinopathy, pars plana vitrectomy and use of intraoperative PFO was associated with retinal reattachment and preserved visual acuity in most eyes.

Adolescent↗
PubMed1986

Catalysis of singlet oxygen production in the reaction of hydrogen peroxide and hypochlorous acid by 1,4-diazabicyclo[2.2.2]octane (DABCO).

The kinetics of the singlet oxygen production in the hydrogen peroxide plus hypochlorous acid reaction were studied by measuring the time course of the singlet oxygen emission at 1268 nm. The addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) increased the peak intensity of the chemiluminescence, but decreased its duration. The increased rate of singlet oxygen production likely accounts for the enhancement of singlet oxygen dimol emission reported in 1976 by Deneke and Krinsky (J. Am. Chem. Soc. 98, 3041-3042). This phenomenon was not seen when singlet oxygen was generated with the reaction of hypobromous acid and hydrogen peroxide. Thus, the enhancement of red chemiluminescence by DABCO should not be regarded as a general test for the production of singlet oxygen in complex biochemical systems.

Catalysis↗
PubMed1998

Unexpected antipsychotic-like activity with the muscarinic receptor ligand (5R,6R)6-(3-propylthio-1,2,5-thiadiazol-4-yl)-1-azabicyclo[3.2.1]octane .

(5R,6R)6-(3-propylthio-1,2,5-thiadiazol-4-yl)-1-azabicyclo[3 .2.1]octane (PTAC) is a potent muscarinic receptor ligand with high affinity for central muscarinic receptors and no or substantially less affinity for a large number of other receptors or binding sites including dopamine receptors. The ligand exhibits partial agonist effects at muscarinic M2 and M4 receptors and antagonist effects at muscarinic M1, M3 and M5 receptors. PTAC inhibited conditioned avoidance responding, dopamine receptor agonist-induced behavior and D-amphetamine-induced FOS protein M5 expression in the nucleus accumbens without inducing catalepsy, tremor or salivation at pharmacologically relevant doses. The effect of PTAC on conditioned avoidance responding and dopamine receptor agonist-induced behavior was antagonized by the acetylcholine receptor antagonist scopolamine. The compound selectively inhibited dopamine cell firing (acute administration) as well as the number of spontaneously active dopamine cells (chronic administration) in the limbic ventral tegmental area (A10) relative to the non-limbic substantia nigra, pars compacta (A9). The results demonstrate that PTAC exhibits functional dopamine receptor antagonism despite its lack of affinity for the dopamine receptors and indicate that muscarinic receptor partial agonists may be an important new approach in the medical treatment of schizophrenia.

Animals↗
PubMedDate not supplied

Synthesis and mu-opioid receptor affinity of a new series of nitro substituted 3,8-diazabicyclo[3.2.1]octane derivatives.

A new series of analogues (1c-j; 2c-i) of the previously reported analgesic 3,8-diazabicyclo[3.2.1]octanes (1a,b; 2a,b) was synthesized and tested for their affinity towards mu-opioid receptors. Modifications were introduced either at the cinnamyl or the acyl side chains. The majority of the new compounds, with the exception of 1c,j and 2c, showed Ki values better or comparable with those of the models.

Animals↗
PubMed2003

Variation of surface properties and textural features of spinel ZnAl2O4 and perovskite LaMnO3 nanoparticles prepared via CTAB-butanol-octane-nitrate salt microemulsions in the reverse and bicontinuous states.

Two binary oxides, a spinel, ZnAl2O4, and a typical perovskite, LaMnO3, have been prepared via CTAB-1-butanol-n-octane-nitrate salt microemulsion in the reverse and bicontinuous states. The exact point of the reverse and bicontinuous states of the microemulsion used in the synthesis was determined by conductivity experiments. The materials obtained after heating at 800 degrees C were characterized by XRD analysis for their crystal structure, N2 porosimetry for their surface area and porosity, and SEM and TEM photography for their texture. The ZnAl2O4 spinel obtained via the reverse microemulsion appears in SEM in a more fragmented form and with a higher specific surface area (143.7 m(2)g(-1)), compared to the corresponding solid prepared via the bicontinuous microemulsion, which appears more robust with lower surface area (126.7 m(2)g(-1)). Nevertheless both materials reveal in TEM a sponge-like structure. The perovskite materials LaMnO3 prepared via the reverse microemulsion showed in SEM a peculiar doughnut-like texture, each doughnut-like secondary particle having a diameter of 2 microm. The corresponding sample developed via the bicontinuous microemulsion showed in SEM uniform secondary particles of size approximately 0.2 microm. Both perovskite samples LaMnO3 appear well crystallized with relative low surface areas, 23.7 m(2)g(-1) for the reverse sample and 10.9 m(2)g(-1) for the bicontinuous one. The TEM photographs reveal that both of them, of reversed and bicontinuous origin, are made up of primary nanoparticles in the size range 40-100 nm. In SEM those materials showed a different secondary structure.

Journal Article↗
PubMed2000

Outcomes and complications associated with perfluoro-n-octane and perfluoroperhydrophenanthrene in complex retinal detachment repair.

OBJECTIVE: To compare rates of perfluorocarbon liquid (PFCL) intraocular retention, anatomic and visual acuity outcomes, and complications associated with intraoperative perfluoro-n-octane (Perfluoron) versus perfluoroperhydrophenanthrene (Vitreon) in retinal detachment repair. DESIGN: Retrospective noncomparative consecutive case series. PARTICIPANTS AND METHODS: Records of consecutive patients who underwent retinal detachment repair with intraoperative Perfluoron (n = 78) or Vitreon (n = 84) at the Bascom Palmer Eye Institute between November 1, 1991, and October 31, 1994, were retrospectively reviewed. MAIN OUTCOME MEASURES: Comparison of PFCL intraocular retention rates, retinal reattachment rates, visual acuity outcomes, and postoperative complication rates between the Perfluoron and Vitreon groups at postoperative day 1, week 1, month 1, month 3, and month 6. To assess the study's generalizability, the Perfluoron data obtained in the current study were compared with results of the Perfluoron Multicenter Clinical Study. RESULTS: Retained Perfluoron was noted less frequently (P < 0.03) than retained Vitreon at each postoperative visit assessed. At 6 months postoperatively, the cumulative rate of retained PFCL (noted at any of the study postoperative visits) was 7.8% of patients in the Perfluoron group and 38.3% in the Vitreon group (P < 0.001). No significant difference was found between the groups in retinal reattachment rates; at 6 months postoperatively, the retina was attached in 45 of 61 (74%) patients in the Perfluoron group and 36 of 57 (63%) patients in the Vitreon group (P = 0.2). There was a trend (P = 0.055) toward better 6-month visual acuity in the Perfluoron group compared with the Vitreon group. The incidence of corneal abnormality at any study visit was 46.7% in the Perfluoron group and 77.4% in the Vitreon group (P < 0.001). At 6 months postoperatively, the cumulative rate of elevated intraocular pressure (>25 mmHg) was 13 +/- 4% and 37 +/- 5%, respectively (P = 0.004). No significant difference was found between the groups in rates of postoperative hypotony. Results of this study are comparable with those observed in the Perfluoron Multicenter Clinical Study. CONCLUSIONS: In this study, Perfluoron was retained intraocularly less frequently than Vitreon. Although no significant difference was found between groups in retinal reattachment rates, Perfluoron is associated with slightly better 6-month visual acuity and lower rates of corneal abnormality and elevated intraocular pressure compared with Vitreon.

Adolescent↗