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PubMed1974

Fusion and compatibility of camphor and octane plasmids in Pseudomonas.

The octane (OCT) plasmid in Pseudomonas putida derived from the omega-hydroxylase-carrying strain of Coon and coworkers is transferable to the camphor (CAM) plasmid-bearing strain by conjugation or by transduction. While the majority of the Cam (+)Oct(+) exconjugants segregate Cam(+) or Oct(+) cells, exconjugants with stable Cam (+)Oct(+) phenotype (CAM-OCT) can be detected at a low frequency. The transductants are all of the CAM-OCT phenotype. In the stable Cam (+)Oct(+) strains, the OCT plasmid resembles the CAM plasmid with respect to curing by mitomycin C, transfer in conjugation, and reaction to ts (temperature-sensitive) mutation specifically affecting CAM plasmid replication. Therefore, it is suggested that certain regions of homology exist between the CAM and OCT plasmids that enable them to recombine to form a single plasmid, and to overcome the incompatibility barrier that prevents their coexisting.

Alkanes↗
PubMed2004

The role of hydrophobic interactions in catalysis of RNA cleavage by 1,4-diazabicyclo[2.2.2]-octane based artificial ribonucleases.

Molecular interactions of RNA cleaving compounds-conjugates of 1,4-diazabicyclo[2.2.2.]octane substituted at the bridge position with tetradecamethylene fragment and imidazole were investigated using light scattering and small angle x-ray scattering methods. The compounds are known to efficiently cleave RNA and one source of the activity could result from micellar catalysis. It was found that the compounds indeed are capable of forming complex aggregates in solution. However, maximal efficacy of RNA cleavage by the conjugates is observed at concentrations well below the concentration required for micelle formation.

Catalysis↗
PubMed2004

Toward the development of metal-free synthetic nucleases: cleavage of a model substrates by 1,4-diazabicyclo[2.2.2]octane derivatives.

Artificial ribonucleases of A(n)BCL series were synthesized by solid-phase method. They consist of a hydrophobic alkyl radical A (n = 3-12 carbon atoms), an "RNA-binding domain" B (bisquaternary salt of 1,4-diazabicyclo[2.2.2]octane), a "catalytic domain" C (histidine residue) and a "linker" L that joins the domains B and C. The effect of the alkyl radical on the catalytic properties of the chemical catalyst was studied using three activated phosphate ester substrates: p-nitrophenyl phosphate, bis-p-nitrophenyl phosphate, and thymidine-3'-p-nitrophenyl phosphate.

Deoxyribonucleases↗
PubMed1994

The use of perfluoro-octane in the management of giant retinal tears without proliferative vitreoretinopathy.

PURPOSE: A technique for managing giant retinal tears without proliferative vitreoretinopathy (PVR) is presented, and visual outcome, anatomic reattachment, and postoperative complications are discussed. METHODS: A total of 25 consecutive cases of retinal detachment from giant retinal tears in eyes without PVR that had not previously undergone surgery were reviewed. A surgical technique combining pars plana vitrectomy, perfluoro-octane, and fluid-gas exchange was used. Scleral buckling was performed in 23 (92%) of 25 eyes, and pars plana lensectomy was performed in 11 (69%) of the 16 phakic eyes. A minimum follow-up period of 6 months was documented in each case. RESULTS: Of the 25 eyes, redetachment occurred in 3 (12%) after the initial procedure, and further surgery was necessary to successfully reattach the retina. A total of 9 secondary procedures were performed in 7 (28%) of the 25 eyes. Final retinal reattachment was achieved in all 25 eyes. Final Snellen visual acuity was 20/80 or better in 18 (72%) patients and 20/200 or better in 21 (84%) patients. CONCLUSION: The anatomic and visual results of this method of surgical treatment of giant retinal tears without PVR compare favorably to those achieved with techniques that use a nonbuckling approach, but with reduced ocular morbidity.

Adolescent↗
PubMed2001

Dynamical fluctuation of the mesoscopic structure in ternary C12E5-water-n-octane amphiphilic system.

Dynamical fluctuations of the bicontinuous microemulsion and lamellar structures in ternary C12E5-water-n-octane amphiphilic system are studied by means of neutron spin echo (NSE) spectrometry. The decay rates of the time correlation of the concentration were analyzed in terms of three theories: (1) A. G. Zilman and R. Granek, Phys. Rev. Lett. 77, 4788 (1996), (2) M. Nonomura and T. Ohta, J. Chem. Phys. 110, 7516 (1999), and (3) R. Granek and M. E. Cates, Phys. Rev. A 46, 3319 (1992), in the first of which a Langevin equation for membrane plaquettes and in the latter two of which time-dependent Ginzburg-Landau equations for the order parameters are considered. The result shows that the intermediate correlation functions I(q,t) for the ranges of 0<t<15 ns and 0<q<0.2 A (-1) are well fitted to a stretched exponential function in time, I(q,t)=exp[-(Gammat)(2/3)], for the bicontinuous microemulsion and the lamellar phases of the same systems with the relaxation rate Gamma increasing as q(3) in agreement with theory (1) from which the bending modulus of the membrane kappa was estimated. For more restricted ranges of 0<t<5 ns and 0.05<q<0.15 A (-1) the NSE result can be expressed by an exponential function in time in agreement with theory (2) determined exclusively by hydrodynamic interactions and for extended range of 0<t<10 ns and 0.03<q<0.15 A (-1) by a nonexponential function in agreement with theory (3), from both of which the effective viscosities eta(0) and eta(eff) of the system were estimated. The effective viscosity from the nonexponential eta(eff) is five times greater than that from the simple exponential eta(0) that is almost the same as the literature value. The implication of this result is discussed in terms of the effective viscosity eta(eff) that takes into account the renormalization of the bending modulus of the membrane.

Journal Article↗
PubMed2002

Self-assembled hydrogen-bonded bilayers in 1,4-diazabicyclo[2.2.2]octane-N-(phosphonomethyl)iminodiacetic acid-water (1/1/1.5).

The title compound is a hydrated salt, 1,4-diazoniabicyclo[2.2.2]octane-N-[(hydroxyphosphinato)methyl]iminiodiacetate-water (1/1/1.5), C(6)H(14)N(2)(2+).C(5)H(8)NO(7)P(2-).1.5H(2)O, in which one of the water molecules lies across a twofold rotation axis in space group P2/n. The ionic components are linked into sheets by a combination of a three-centre N-H...(O)(2) hydrogen bond and two-centre O-H...O and N-H...O hydrogen bonds, and these sheets are pairwise linked by the water molecules into bilayers, by means of further O-H...O hydrogen bonds.

Journal Article↗
PubMed2004

1,4-Diazabicyclo[2.2.2]octane-1,4-diium trichromate.

The title compound, (C(6)H(14)N(2))[Cr(3)O(10)], consists of a diazabicyclo[2.2.2]octane-1,4-diium cation and a discrete trichromate anion linked by an N-H.O hydrogen bond. Three CrO(4) tetrahedra are joined via shared O atoms to form the trichromate anion. Supramolecular rings, which can be described by the graph-set motif R(4)(4)(26), are built via N-H.O hydrogen bonds, and C-H.O interactions play lesser roles in forming the structure.

Journal Article↗
PubMed2004

catena-Poly[1,4-diazoniabicyclo[2.2.2]octane [silver(I)-tri-mu-thiocyanato-kappa6S:S]].

The title compound, [(C6H14N2)[Ag(NCS)3]]n, is a polymeric silver(I) complex. The Ag(I) atom is hexacoordinated by the S atoms of six thiocyanate anions, with each thiocyanate S atom acting in a bridging mode to link the Ag atoms together. The unique Ag(I) atom lies at a cell origin and has crystallographically imposed 3 symmetry. The diazonia[2.2.2]octane molecule lies about a site with 6 imposed symmetry with the unique N atom on a threefold axis. The S and N atoms of the thiocyanate ligands sit on a mirror plane and a threefold axis, respectively. The crystal structure consists of one-dimensional chains, which are stabilized by N-H...N hydrogen bonds to form a three-dimensional network.

Journal Article↗
PubMed2004

Diazabicyclo[2.2.2]octane-1,4-diium dichromate.

The title compound, (C(6)H(14)N(2))[Cr(2)O(7)], consists of a diazabicyclo[2.2.2]octane-1,4-diium cation and a discrete dichromate anion, which are linked in the crystal by N-H...O hydrogen bonds. The cation is ordered and distorted, owing to the confinement and twist of the hydrogen bonds involved. Two CrO(4) tetrahedra are joined through a shared O atom to form the dichromate anion. Chiral supramolecular chains of the title compound are built up via N-H...O hydrogen bonds, and C-H...O interactions play subordinate roles in forming the structure.

Journal Article↗
PubMed2005

1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane diiodide acetonitrile solvate.

In the crystal structure of the title compound, C(8)H(18)N(2)(2+).2I(-).CH(3)CN, the dication lies on a mirror plane containing the molecular dication threefold axis. The structure displays C-H...I interactions between H atoms of the 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane dication and the iodide anions. The H...I distances are in the range 2.96-3.18 (4) A. The dications pack forming channels along the b axis, which contain the iodide anions and acetonitrile solvent molecules.

Journal Article↗
PubMed2002

1-[4-[4[(4R,5R)-3,3-Dibutyl-7-(dimethylamino)-2,3,4,5-tetrahydro-4-hydroxy-1,1-dioxido-1-benzothiepin-5-yl]phenoxy]butyl]-4-aza-1-azoniabicyclo[2.2.2]octane methanesulfonate (SC-435), an ileal apical sodium-codependent bile acid transporter inhibitor alters hepatic cholesterol metabolism and lowers plasma low-density lipoprotein-cholesterol concentrations in guinea pigs.

Male Hartley guinea pigs (10/group) were assigned either to a control diet (no drug treatment) or to diets containing 0.4, 2.2, or 7.3 mg/day of an ileal apical sodium-codependent bile acid transporter (ASBT) inhibitor, 1-[4-[4[(4R,5R)-3,3-dibutyl-7-(dimethylamino)-2,3,4,5-tetrahydro-4-hydroxy-1,1-dioxido-1-benzothiepin-5-yl]phenoxy]butyl]-4-aza-1-azoniabicyclo[2.2.2] octane methanesulfonate (SC-435). Based on food consumption, guinea pigs received 0, 0.8, 3.7, or 13.4 mg/kg/day of the ASBT inhibitor. The amount of cholesterol in the four diets was maintained at 0.17%, equivalent to 1200 mg/day in the human situation. Guinea pigs treated with 13.4 mg/kg/day SC-435 had 41% lower total cholesterol and 44% lower low-density lipoprotein (LDL)-cholesterol concentrations compared with control (P < 0.01), whereas no significant differences were observed with either of the lower doses of SC-435. Hepatic cholesterol esters were significantly reduced by 43, 56, and 70% in guinea pigs fed 0.8, 3.7, and 13.4 mg/kg/day of the ASBT inhibitor, respectively (P < 0.01). In addition, the highest dose of the inhibitor resulted in a 42% increase in the number of very low-density lipoprotein (VLDL) triacylglycerol molecules and a larger VLDL diameter compared with controls (P < 0.05). Acyl-CoA cholesterol/acyltransferase activity was 30% lower with the highest dose treatment, whereas cholesterol 7alpha-hydroxylase, the regulatory enzyme of bile acid synthesis, was 30% higher with the highest ASBT inhibitor dose (P < 0.05). Furthermore, bile acid excretion increased 2-fold with the highest dose of SC-435 compared with the control group (P < 0.05). These results suggest that the reduction in total and LDL-cholesterol concentrations by the ASBT inhibitor is a result of alterations in hepatic cholesterol metabolism due to modifications in the enterohepatic circulation of bile acids.

Animals↗
PubMed2005

1,4-Diazabicyclo[2.2.2]octane derivatives: a novel class of voltage-gated potassium channel blockers.

Voltage-gated potassium (Kv) channels are targets for therapeutic drugs in the treatment of pathologic conditions including cardiac arrhythmia and epilepsy. In this study, we synthesized three classes of novel polyammonium compounds incorporating the bicyclic unit 1,4-diazabicyclo[2.2.2]octane (DABCO) and tested their action on three representative mammalian Kv channels (Kv2.1, Kv3.4, and Kv4.2) expressed in Xenopus laevis oocytes. Nonsubstituted DABCO did not block the Kv channels tested. Simple DABCO monostrings and diDABCO strings inhibited Kv2.1 and Kv3.4 channels, with potency increasing with string length for both these DABCO classes. Both Kv2.1 and Kv3.4 were most sensitive to C16 monostrings, with IC50 values of 1.9 and 0.6 microM, respectively. For compounds comprising two DABCO groups separated by an aromatic ring, inhibition depended upon relative positioning of the two DABCO groups, and only the para form (JC638.2alpha) was active, blocking Kv2.1 with an IC50 of 186 microM. Kv4.2 channels were relatively insensitive to all compounds tested. Unlike the tetraethylammonium ion (TEA), neither JC638.2alpha nor C16 monostring TA279 produced block when applied intracellularly via the recording electrode to Kv2.1 channels expressed in Chinese hamster ovary cells, suggesting against an internal site of action. However, JC638.2alpha protected an introduced cysteine (K356C) in the Kv2.1 outer pore from permanent modification by methanethiosulfonate ethyltrimethylammonium (MTSET). These data suggest that JC638.2alpha occupies an external binding site similar to that of TEA in the Kv2.1 outer pore, but with much higher affinity than TEA. These DABCO salts represent a new class of Kv channel blockers, some with higher potencies than any previously described quaternary ammonium ions. The potential for synthesis of an array of modular derivatives suggests that DABCO compounds hold promise as probes of Kv channel structure and identity and as potential therapeutic agents.

Animals↗
PubMed2005

An octane-fueled solid oxide fuel cell.

There are substantial barriers to the introduction of hydrogen fuel cells for transportation, including the high cost of fuel-cell systems, the current lack of a hydrogen infrastructure, and the relatively low fuel efficiency when using hydrogen produced from hydrocarbons. Here, we describe a solid oxide fuel cell that combines a catalyst layer with a conventional anode, allowing internal reforming of iso-octane without coking and yielding stable power densities of 0.3 to 0.6 watts per square centimeter. This approach is potentially the basis of a simple low-cost system that can provide substantially higher fuel efficiency by using excess fuel-cell heat for the endothermic reforming reaction.

Journal Article↗
PubMed1998

Effects of N-[2-(1-azabicyclo[3,3,0]octan-5-yl)ethyl]2-nitroaniline fumarate (SK-946), a novel cognition activator, on learning and memory in rodent models.

We examined the effects of N-[2-(1-azabicyclo[3,3,0]octan-5-yl)ethyl]2-nitroaniline fumarate (SK-946) on cognition in various rodent models. SK-946 slightly suppressed spontaneous motor activity, but had no effect on scopolamine-induced motor facilitation. SK-946 ameliorated scopolamine-, pirenzepine-, cycloheximide- and electric shock-induced passive avoidance deficits in rodents when administered before acquiring the training. In an active avoidance test, SK-946 accelerated avoidance acquisition in the later half of training without a marked increase in lever-pressing. In more reliable models of cognitive disorders, i.e. an AF64A intracerebroventricular infusion model using the step-through passive avoidance test, an aged rat model using the step-down passive avoidance test and methylazoxymethanol (MAM)-induced microencephalic rat model using the Morris water maze test, SK-946 ameliorated impaired learning and memory. These results suggest an ability of SK-946 to enhance cognitive functions.

Aging↗
PubMed1998

Characterization of the neurochemical effects of N-[2-(1-azabicyclo[3,3,0]octan-5-yl)ethyl]2-nitroaniline fumarate (SK-946) as a cognition activator.

The neurochemical effects of SK-946, N-[2-(1-azabicyclo[3,3,0]octan-5-yl)ethyl]2-nitroaniline fumarate, were investigated in an attempt to elucidate cognition activating properties. In rat brain cortical membranes and in cloned human receptors expressed in Sf9 cells, SK-946 had submicromolar affinities for muscarinic receptors with a moderate selectivity for M1 (m1) sites. Although no increase in the antagonist (N-methylscopolamine)/agonist (oxotremorine-M) binding ratio was observed, SK-946 exhibited a partial agonistic effect on receptor-stimulated phosphoinositide hydrolysis in primary cultured rat fetal hippocampal cells. Heterogeneous, reversible and concentration-dependent excitations of the hippocampal neuronal cells treated with SK-946 (10(-5)-10(-3) M) were confirmed as increases in cytosolic Ca2+ concentrations measured in Fura-PE3 preloaded cells. Furthermore, SK-946 (>10(-5) M) increased [3H]myo-inositol uptake into the hippocampal cells. On the other hand, SK-946 had no effect on adenylate cyclase activities in primary cultured rat heart cells, and showed a weak antagonistic effect on carbachol-induced adenylate cyclase inhibition, suggesting that it is an M2 antagonist. Using in vivo microdialysis, it was found that relatively low concentrations (<10(-7) M) of SK-946 increased acetylcholine release and decreased choline content in that hippocampal area in rats. These results suggest that SK-946 accelerates muscarinic neuronal transmission in the central nervous system.

Acetylcholine↗
PubMed1998

Serotonin 5-HT4 receptor agonistic activity of the optical isomers of (+/-)-4-amino-N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-5-chloro-2,3- dihydro-2-methylbenzo[b]furan-7-carboxamide.

The enantiomers, (R)-(-)-1 and (S)-(+)-1, of (+/-)-4-amino-N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-5-chloro-2,3- dihydro-2-methylbenzo[b]furan-7-carboxamide [(+/-)-1] were prepared from optically active benzyl 4-acetylamino-2,3-dihydro-2-methylbenzo[b]furan-7-carboxylate [(R)-(+)-6, (S)-(-)-6], respectively. The requisite (R)-(+)-6 and (S)-(-)-6 were prepared by large-scale preparative HPLC on chiral stationary phases (CSPs). The absolute configuration of (S)-(+)-1 was determined by single crystal X-ray analysis. The serotonin 5-HT4 receptor agonistic activity of (S)-(-)-1 hemifumarate (SK-951) which was hemifumarate of (S)-(+)-1 was about twice that of the other enantiomer (R)-(+)-1 hemifumarate which was hemifumarate of (R)-(-)-1.

Animals↗