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At least 415 records · Page 23Linked to original sources
PubMed2004

Removal of retained subfoveal perfluoro-n-octane liquid.

PURPOSE: To report a novel technique to remove retained submacular perfluorocarbon liquid. DESIGN: Retrospective cases series. METHODS: Two patients with retained subfoveal perfluorocarbon liquid were treated with this technique. With a three-port pars plana approach, a 39-gauge flexible cannula was used to perform a retinotomy adjacent to the subfoveal perfluorocarbon bubble. The tip of the cannula was inserted into the bubble, which was removed with active suction. RESULTS: Both patients underwent successful removal of the perfluorocarbon liquid without complications. In one patient, visual acuity improved from 20/70 to 20/30, with resolution of his preoperative central scotoma. The second patient required removal of subfoveal perfluorocarbon liquid at the time of silicone oil removal. The preoperative vision of finger counting improved to 20/60. CONCLUSIONS: Subretinal perfluorocarbon can be removed using a flexible 39-gauge cannula without inducing retinal detachment or making a large retinotomy. This technique may benefit patients with retained subfoveal perfluorocarbon liquid.

Catheterization↗
PubMed2006

Selection of a 2-azabicyclo[2.2.2]octane-based alpha4beta1 integrin antagonist as an inhaled anti-asthmatic agent.

The alpha4beta1 integrin, expressed on eosinophils and neutrophils, induces inflammation in the lung by facilitating cellular infiltration and activation. From a number of potent alpha4beta1 antagonists that we evaluated for safety and efficacy, 1 was selected as a lead candidate for anti-asthma therapy by the inhalation route. We devised an optimized stereoselective synthesis to facilitate the preparation of a sufficiently large quantity of 1 for assessment in vivo. Administration of 1 to allergen-sensitive sheep by inhalation blocked the late-phase response of asthma and abolished airway hyper-responsiveness at 24h following the antigen challenge. Additionally, the recruitment of inflammatory cells into the lungs was inhibited. Administration of 1 to ovalbumin-sensitized guinea pigs intraperitoneally blocked airway resistance and inhibited the recruitment of inflammatory cells.

Administration, Inhalation↗
PubMed2005

Discovery and activity of (1R,4S,6R)-N-[(1R)-2-[4-cyclohexyl-4-[[(1,1-dimethylethyl)amino]carbonyl]-1-piperidinyl]-1-[(4-fluorophenyl)methyl]-2-oxoethyl]-2-methyl-2-azabicyclo[2.2.2]octane-6-carboxamide (3, RY764), a potent and selective melanocortin subtype-4 receptor agonist.

A novel isoquinuclidine containing selective melanocortin subtype-4 receptor small molecule agonist, 3 (RY764), is reported. Its in vivo characterization revealed mechanism-based food intake reduction and erectile activity augmentation in rodents.

Animals↗
PubMed2003

Binding of fullerene C60 to gold surface functionalized by self-assembled monolayers of 8-amino-1-octane thiol: a structure elucidation.

The formation of self-assembled chemisorbed monolayers (SAM) of 8-amino-1-undecane thiol functionalized with fullerene C(60) on gold, has been studied by contact angle measurements, Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). A two-step procedure was followed consisting of the chemisorption of amine-terminated organosulfur compounds, followed by their reaction with fullerenes at the solid-liquid interface. Covalent binding of fullerenes to these attachment layers was accessed by FTIR-ATR and XPS. ATR showed several major features in the C(60) skeleton ring vibration region along with all the characteristic features of the aminothiol. With increase in carbon to sulfur ratio, appearance of a C1s shake-up satellite peak due to the characteristic pi-pi(*) transition of the C(60) backbone and a low binding energy N1s feature confirmed the z.sbnd;NH(2) binding at the 6,6 double bond of the C(60) cage. Possible explanations for these experimental findings are discussed.

Journal Article↗
PubMed2003

Stereochemical memory in the regioselective and diastereoselective rearrangement of tricyclo[3.3.0.0 2,4]octanes (housanes) by electron transfer (1,3-cyclopentanediyl radical cations) and acid (cyclopentyl carbenium ions) and silver-ion catalysis.

The electron-transfer-catalyzed rearrangement of the housanes 5 affords regioselectively only the two cyclopentenes 6 (CH(3) migration) and 7 (R migration) by 1,2-migration of the two groups at the methano bridge to the methyl terminus. The 1,2-shift of the CH(3) group prevails, and the rearrangement ratio is essentially insensitive to the migratory aptitude of the R substituent. This stereochemical memory effect derives from the conformational impositions on the stereoelectronic requirements during the 1,2-migration in the 1,3-radical-cation intermediates. Similar regioselectivities and diastereoselectivities are observed for the TFA-catalyzed and silver(I)-ion-promoted rearrangements, whereas the rearrangement catalyzed by HClO(4) affords a complete reversal in the product selectivity and both the regioselectivity and the diastereoselectivity are much reduced. Migration to the phenyl terminus is favored to afford the 6' and 7' cyclopentenes, of which the former (CH(3) migration) dominates. For the minor regioisomer, only the cyclopentene 6 is formed by an exclusive 1,2-shift of the CH(3) group. This dichotomy in product selectivities is rationalized in terms of two distinct mechanisms for the various activation modes: a common one for the electron-transfer-induced, TFA-catalyzed, and silver(I)-ion-promoted rearrangements and a different one for HClO(4).

Journal Article↗
PubMed1994

Synthesis of 2 beta-acyl-3 beta-aryl-8-azabicyclo[3.2.1]octanes and their binding affinities at dopamine and serotonin transport sites in rat striatum and frontal cortex.

A novel entry to tropane analogs of cocaine was developed on the basis of the reaction of rhodium-stabilized vinylcarbenoids with pyrroles. These analogs were tested in binding to dopamine and serotonin (5-HT) transporters in membranes from rat striatum and frontal cortex. In all the analogs, the aryl group at the 3-position was directly bound to the tropane ring (as in WIN-35,428), and methyl or ethyl ketone moieties were present at the 2-position instead of the typical ester group. The series of analogs containing a 2-naphthyl group at the 3-position were most potent, with Ki values < 1 nM in binding to both dopamine and 5-HT transporters. Although the unsubstituted 2-naphthyl analog was nonselective at dopamine and 5-HT transport sites, other compounds were selective for either site. In general, compounds with relatively small substituents on the aromatic moiety (such as p-methyl or p-fluoro) were relatively selective for the dopamine transporters, while a p-isopropylphenyl derivative was selective for the 5-HT transport sites. This latter compound represents the first N-methyltropane derivative specific for 5-HT transporters. Resolution of two of the most significant analogs was achieved by HPLC on a chiral stationary phase; the active enantiomer of a 2-naphthyl analog exhibited Ki values of < 0.1 nM at both dopamine and 5-HT transporter sites.

Animals↗
PubMed2001

Synthesis of 2beta-acyl-3beta-(substituted naphthyl)-8-azabicyclo[3.2.1]octanes and their binding affinities at dopamine and serotonin transport sites.

A series of 3beta-naphthyltropane derivatives were synthesized and found to show high affinity at both the dopamine and serotonin transporter sites, leading to some of the most potent inhibitors known based on the tropane structure. Comparative molecular field analysis (CoMFA) models were developed for both dopamine and serotonin transporter binding data. These models provide insights into those factors that influence binding at the two transporters.

Animals↗
PubMed1991

Novel site-directed affinity ligands for GABA-gated chloride channels: synthesis, characterization, and molecular modeling of 1-(isothiocyanatophenyl)-4-tert-butyl-2,6,7-trioxabicyclo[2.2.2]octanes .

p-, m-, and o-isothiocyanate derivatives (1-3, respectively) of tert-butylbicycloorthobenzoate (TBOB) were synthesized from 3-tert-butyloxetane-3-methanol (4) as the starting material. While 2 was readily obtained in four steps via catalytic hydrogenation of the m-nitro-tert-butylbicycloorthobenzoate (9) intermediate, 1 and 3 could not be obtained this way. 1 and 3 were instead synthesized by an alternative four-step approach while made use of the stability of the isothiocyanate moiety to strong Lewis acids such as boron trifluoride etherate, conditions that would isomerize isothiocyanato oxetane ester intermediates to their corresponding orthoesters. The p-isothiocyanate derivative of TBOB, compound 1, inhibited [35S]-tert-butylbicyclophosphorothionate (TBPS) binding to rat cortical membranes with a potency (IC50 62 nM) comparable to the parent compound while 2 and 3 were approximately 10-fold less potent (IC50 values 570 and 609 nM, respectively). Preincubating tissue with radioligand further reduced the potencies of 2 and 3 by approximately 1 order of magnitude (IC50 values 5400 and 7500 nM, respectively) while the potency of 1 (IC50 90 nM) was only marginally affected by this procedure. Pretreatment of membranes with 1 and 2 followed by extensive washing resulted in a concentration-dependent inhibition of [35S]TBPS binding. In contrast, preincubating tissues with up to 2.4 microM of 3 did not elicit an apparent acylation of [35S]TBPS binding sites. Molecular modeling of the effective diameters of 1-3 in their thermodynamically most stable conformations indicates a relationship between these diameters and their relative efficacies as site-directed acylators; the smaller the diameter, the more potent the acylator. This hypothesis explains both the relative potencies of these compounds and their differential abilities to acylate the TBPS binding site.

Animals↗