Search results for "Isomer"

Cromakalim inhibits electrically-evoked [3H]acetylcholine release from a tube-preparation of the rat isolated trachea by an epithelium-dependent mech…

1993

Rat isolated tracheae were labelled by incubation with [3H]choline to measure the tritium efflux elicited by electrical stimulation of the extrinsic parasympathetic nerves in vitro. Stimulated tritium efflux reflects the neuronal release of newly synthesized acetylcholine; the effects of potassium channel openers on the stimulated tritium efflux were investigated. In tracheae opened longitudinally neither cromakalim nor its 3S,4R-enantiomer, BRL 38227, reduced the stimulated tritium efflux, whereas in intact tube-preparations cromakalim (0.01-1 mumol/l) mediated a concentration-dependent inhibition. The inhibitory effect of 1 mumol/l cromakalim was prevented by 0.1 mumol/l glibenclamide. Li…

Pharmacokinetic evaluation of esomeprazole for the treatment of gastroesophageal reflux disease

2014

Proton pump inhibitors (PPIs) are widely used for the treatment of acid-related diseases such as gastroesophageal reflux disease (GERD). They are recommended by the American College of Gastroenterology for healing erosive esophagitis (EO) and as long-term treatment in patients with healed EO. The available PPIs differ somewhat in their pharmacokinetics and clinical properties, but whether these differences are of clinical relevance is a matter of debate. Some safety concerns have been raised with the use of PPIs, mostly an increased incidence of infectious diseases such as community-acquired pneumonia or Clostridium difficile diarrhea.This article explores the results of clinical studies on…

Synthesis and in vitro evaluation of (S)-2-([11C]methoxy)-4-[3-methyl-1-(2-piperidine-1-yl-phenyl)-butyl-carbamoyl]-benzoic acid ([11C]methoxy-repagl…

2004

The 11 C-labeled sulfonylurea receptor 1 (SUR1) ligand (S)-2-(( 11 C)methoxy)-4-(3-methyl-1-(2-piperidine-1-yl-phenyl)- butyl-carbamoyl)-benzoic acid (( 11 C)methoxy-repaglinide) was synthesized in an overall radiochemical yield of 35% after 55 min with a radiochemical purity higher than 99%. This compound is considered for the noninvasive investigation of the SUR1 receptor status of pancreatic b-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. The specific activity was 40-70 GBq/lmol. In vitro testing of the nonradioactive methoxy-repaglinide was performed to characterize the affinity for binding to the human SUR1 isoform. Methoxy-repaglinide induce…

Enantioselective determination of plasma protein binding of common amphetamine-type stimulants.

2021

Amphetamine-type stimulants (ATS) like amphetamine ('speed'), methamphetamine ('crystal meth') and 3,4-methylenedioxy-N-methylamphetamine (MDMA, 'ecstasy') represent some of the most frequently abused drugs worldwide. Another less frequently abused ATS is 4-fluoroamphetamine (4-FA). The enantiomers of these four compounds exhibit different pharmacokinetic and pharmacodynamic properties. According to the free drug theory, the pharmacological properties of a substance are dependent on its plasma protein binding (PPB). However, data on PPB of stimulant enantiomers in humans are rare or non-existent. Human plasma samples were spiked with racemic mixtures of the stimulants and subjected to ultra…

Melting point, molecular symmetry and aggregation of tetrachlorobenzene isomers: the role of halogen bonding

2018

Tetrachlorobenzenes represent one of the best known, but not yet fully understood, group of isomers of the structure–melting point relationship. The differences in melting temperatures of these structurally related compounds were rationalized in terms of the hierarchy and nature of formed noncovalent interactions, and the molecular aggregation that is influenced by molecular symmetry. The highest melting point is associated with the highly symmetric 1,2,4,5-tetrachlorobenzene isomer. The structures of less symmetrical 1,2,3,4-tetrachlorobenzene and 1,2,3,5-tetrachlorobenzene, determined at 270 and 90 K, show a distinct pattern of halogen bonds, characterized by the different numbers and typ…

Chemoselective, Substrate-directed Fluorination of Functionalized Cyclopentane β-Amino Acids

2016

This work describes a substrate-directed fluorination of some highly functionalized cyclopentane derivatives. The cyclic products incorporating CH2 F or CHF2 moieties in their structure have been synthesized from diexo- or diendo-norbornene β-amino acids following a stereocontrolled strategy. The synthetic study was based on an oxidative transformation of the ring carbon-carbon double bond of the norbornene β-amino acids, followed by transformation of the resulted "all cis" and "trans" diformyl intermediates by fluorination with "chemodifferentiation".

Response to comment on Properties and inter­actions – melting point of tri­bromo­benzene isomers

2022

Recent experiments at the JYFLTRAP Penning trap

2020

AbstractThe JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility offers excellent possibilities for high-precision mass measurements of radioactive ions. Around 400 atomic masses, including around 50 isomeric states, have been measured since JYFLTRAP became operational. JYFLTRAP has also been used as a high-resolution mass separator for decay spectroscopy experiments as well as an ion counter for fission yield studies. In this contribution, an overview of recent activities at the JYFLTRAP Penning trap is given, with a focus on nuclei discussed in the PLATAN2019 meeting.

Studying Gamow-Teller transitions and the assignment of isomeric and ground states at $N=50$

2022

Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below $^{100}$Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of $^{124}$Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of $^{98}$Cd and $^{97}$Rh. A new QEC=5437±67 keV was obtained for $^{98}$Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+…

Hexagonal Microparticles from Hierarchical Self-Organization of Chiral Trigonal Pd3L6 Macrotetracycles

2021

Construction of structurally complex architectures using inherently chiral, asymmetric, or multi-heterotopic ligands is a major challenge in metallosupramolecular chemistry. Moreover, the hierarchical self-organization of such complexes is unique. Here, we introduce a water-soluble, facially amphiphilic, amphoteric, chiral, asymmetric, and hetero-tritopic ligand derived from natural bile acid, ursodeoxycholic acid. We show that via the supramolecular transmetalation reaction, using nitrates of Cu(II) or Fe(III), and subsequently Pd(II), a superchiral Pd3L6 complex can be obtained. Even though several possible constitutional isomers of Pd3L6 could be formed, because of the ligand asymmetry a…