bluuebunny/crossref_metadata_2025_split huggingface dataset:
The non–major histocompatibility complex quantitative trait locus Cia10 contains a major arthritis gene and regulates disease severity, pannus formation, and joint damage
Authors: Brenner Max , Meng Hsiang‐Chi , Yarlett Nuriza C. , Griffiths Marie M. , Remmers Elaine F. , Wilder Ronald L. , Gulko Pércio S. 
Published: January 2005

AbstractObjectiveTo construct rats congenic for the chromosome 2 arthritis‐regulatory quantitative trait locus Cia10, originally identified in a (DA × ACI)F2 intercross rat strain that had been assessed for collagen‐induced arthritis (CIA), and to determine the effect of this congenic interval on arthritis severity, joint histologic structure, and cytokine transcription in rats with pristane‐induced arthritis (PIA).MethodsA 52.6‐MB interval derived from the ACI (CIA‐ and PIA‐resistant) strain and containing the Cia10 interval was introgressed into the DA (arthritis‐susceptible) background through genotype‐guided congenic breeding. Homozygous male and female DA.ACI(Cia10) congenic rats were studied for their susceptibility to and severity of PIA, and were compared with same‐sex DA rats. Histologic analyses were done on hind paws collected on day 32 following the pristane injection. Levels of interleukin‐1β (IL‐1β) and tumor necrosis factor α (TNFα) messenger RNA (mRNA) were measured with real‐time polymerase chain reaction on synovial tissues from day‐32 ankles.ResultsBoth male and female DA.ACI(Cia10) congenic rats developed a significantly milder form of arthritis, with a 95% and 92% reduction in the arthritis severity index compared with DA male and female controls, respectively (males P ≤ 0.001 and females P = 0.003). DA.ACI(Cia10) congenic rat synovial tissue was more likely to preserve its normal histologic architecture, including minimal to no cartilage and bone erosions, synovial hyperplasia, and pannus formation, and reduced numbers of vessels (angiogenesis), when compared with DA synovial tissue. There was a 2.7‐ and 2.4‐fold reduction in the amount of IL‐1β and TNFα mRNA, respectively, in the synovial tissue of DA.ACI(Cia10) congenic rats compared with DA rats. Sequencing analyses of complementary DNA for the Cia10‐predicted candidate gene Ptpn8, the rat homolog of the rheumatoid arthritis (RA)–susceptibility gene PTPN22, revealed no polymorphisms between the DA and ACI strains.ConclusionThis study determined that Cia10 harbors a major autoimmune arthritis–regulatory gene. This gene regulates clinical disease severity, histologic damage, and the levels of at least two central proinflammatory cytokines. We are in the process of narrowing down the critical region for positional cloning of the Cia10 gene. The identification of this gene will provide novel targets or pathways for focused candidate‐gene studies in RA.
Small interfering RNA inhibition of SPARC attenuates the profibrotic effect of transforming growth factor β1 in cultured normal human fibroblasts
Authors: Zhou Xiaodong , Tan Filemon K. , Guo Xinjian , Wallis Debra , Milewicz Dianna M. , Xue Sarah , Arnett Frank C. 
Published: January 2005

AbstractObjectiveSPARC (secreted protein, acidic and rich in cysteine), or osteonectin, is a matricellular protein. Recently, it was observed to be overexpressed in fibroblasts obtained from the skin of patients with scleroderma, as well as in different tissues from patients with several other fibrotic disorders. Moreover, a genetic polymorphism in SPARC has been associated with susceptibility to scleroderma. Transforming growth factor β1 (TGFβ1) is a profibrotic cytokine that stimulates excessive collagen production in patients with scleroderma or other fibrotic diseases. The purpose of this study was to examine whether specific inhibition of SPARC can influence the expression of type I collagen and ameliorate the profibrotic activity of TGFβ1 on normal human fibroblasts.MethodsFibroblasts obtained from the skin of 4 healthy individuals were cultured and transfected with SPARC small interfering RNA (siRNA). TGFβ was used as a fibrosis stimulus in cultured fibroblasts. Real‐time quantitative reverse transcriptase–polymerase chain reaction and Western blotting were used to measure transcription and protein levels of SPARC and type I collagen, respectively.ResultsThe fibroblasts transfected with SPARC siRNA showed decreased expression of both SPARC and type I collagen. Exogenous TGFβ1 induced increased expression of both SPARC and type I collagen in cultured normal human fibroblasts, but this response was significantly blunted in the fibroblasts transfected with SPARC siRNA.ConclusionTGFβ1 can induce increased expression of both SPARC and type I collagen. Specific inhibition of SPARC led to decreased expression of type I collagen and attenuated the profibrotic effect of TGFβ1 in cultured normal human fibroblasts. Use of siRNA to silence SPARC represents a potential therapeutic approach to fibrotic disorders such as scleroderma.
Imaging Activation of Two Ras Isoforms Simultaneously in a Single Cell
Authors: Peyker Anna , Rocks Oliver , Bastiaens Philippe I. H. 
Published: January 2005

AbstractFluorescence resonance energy transfer (FRET) microscopy approaches have been used to study protein interactions in living cells. Up to now, due to the spectral requirements for FRET detection, this has been limited to the measurement of single protein interactions. Here we present a novel time‐resolved fluorescence imaging method for simultaneously monitoring the activation state of two proteins in a single cell. A Ras sensor, consisting of fluorescently labelled Ras and a fluorescently labelled Ras binding domain (RBD) of Raf, which reads out Ras activation by its interaction with RBD as a FRET signal, has been adapted for this purpose. By using yellow (YFP) and cyan (CFP) versions of the green fluorescent protein from Aquorea victoria as donors and a tandem construct of Heteractis crispa Red (tHcRed) as acceptor for both donors, two independent FRET signals can be measured at the same time. Measuring the YFP and CFP donor lifetimes by fluorescence‐lifetime imaging microscopy (FLIM) allows us to distinguish the two different FRET signals in a single cell. Using this approach, we show that different Ras isoforms and mutants that localize to the plasma membrane, to the Golgi or to both compartments display distinct activation profiles upon growth‐factor stimulation; this indicates that there is a differential regulation in cellular compartments. The method presented here is especially useful when studying spatiotemporal aspects of protein regulation as part of larger cellular signalling networks.
Evaluation of π‐acid chiral stationary phases deriving from tyrosine and related amino acids for the chromatographic resolution of racemates: Specific requirements for enantiorecognition ability
Authors: Liene M. , Macaudìre P. , Caude M. , Rosset R. , Tambut´ A. 
Published: January 2005

AbstractChromatographic applications of three novel chiral stationary phases (CSPs) deriving from (S)‐(N)‐(3,5‐dinitrobenzoyl)tyrosine are reported, under liquid chromatographic (LC) and subscritical fluid chromatographic (SubFC) conditions. Two grafting modes of the chiral moiety have been experimented starting either from γ‐mercaptopropyl‐silanized (type 1) or γ‐aminopropyl‐silanized (type 2) silica gels. For type 2 CSPs an evaluation of the stability of the amide linkage was achieved by means of SubFC; the relative contriution of ionic and covalent bindings to the ciral recognitio aility was then outlined. The chromatographic properties of these CSPs were compared with those of the corresponding CSPs deriving from phenylglycine, p‐hydroxyphenylglycine, and phenylalanine for the resolution of some tertiary phosphine oxide, naphthoyl amide, and α‐methylene γ‐lactam enantiomers. Some simple requirements regarding the solute and CSP structures for chiral recognition ability can be inferred from these results. In addition, the resolutio of π‐acid α‐N‐(3,5‐dinitrobenzoyl)amino esters was investigated on these π‐acid CSPs. An example of preparative scale chromatography is also presented.
Enantioselective inclusion complexation of 2,3,4,6‐tetra‐O‐acetyl‐D‐glycopyranose as a chiral host with (+)‐(r)‐phenylethylamine: x‐ray characterization of the complex
Authors: Francotte Eric , Rihs Greta 
Published: January 2005

AbstractX‐ray analysis of the crystalline product obtained by reaction of 2,3,4,6‐Tetra‐O‐acetyl‐D‐glycopyranose with phenylethylamine revealed the formation of a real one‐to‐one inclusion complex. This complexaion is highly stereoselective, because only the (+)‐R‐enantiomeric form of the amine is included. Analogies to the mode of complexation of cellulose triaceate with chiral molecules in „inclusion chromatography”︁ are discussed.
Investigation on the enantiomeric impurity of epinephrine hydrochloride injections
Authors: Zhong‐Yuan Yang , Ru‐Zheng Xu 
Published: January 2005

AbstractEpinephrine enantiomers were derived into diastereoisomers with the chiral reagent 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosylisothiocyanate. The resolutions was carried out on a C18 column. The RS between (−)‐R‐ and (+)‐S‐isomers was 2.3. The retention time could be changed by adding a proper amount of acetonirile into the mobile phase. The results showed that (+)‐S‐isomer in the epinephrine hydrochloride injections increased during the period of storage.
Cytochrome P‐450‐catalyzed asymmetric epoxidation of simple prochiral and chiral aliphatic alkenes: species dependence and effect of enzyme induction on enantioselective oxirane formation
Authors: Wistuba D. , Nowotny H.‐P. , Träger O. , Schurig V. 
Published: January 2005

AbstractThe enantioselectivity of the in vitro conversion of simple prochiral and chiral aliphatic alkenes into oxiranes by liver microsomes of untreated or induced (phenobarbital) rats, of untreated or induced (phenobarbital, benzo[α] pyrene) mice, and of humans was determined by complexation gas chromatography. The enantiomeric excess (ee) of the epoxides extends from 0 (trimethyloxirane) to 50% (ethyloxirane). The configuration (R or S) of the enantiomers formed in excess is consistent for homologous oxiranes but is species dependent and in some cases influenced by enzyme induction. Enantioselectivity differences of aliphatic alkene epoxidation by human liver microsomes of four individuals are negligible.
Optical enrichment of dansyl‐rac‐amino acids by formation of crystalline inclusion complexes with cyclodextrins
Authors: Jin Heng L. , Stalcup Apryll , Armstrong Daniel W. 
Published: January 2005

AbstractOptical enrichment from racemic dansyl‐leucine, dansyl‐norleucine, and dansyl‐phenylalanine with both β‐ and γ‐cyclodextrins in water is reported. Initial crystallization yielded the dansyl‐L‐leucine isomer complexed in excess with β‐cyclodextrin with an optical purity of 62–78% depending on experimental conditions. The optical purities obtained for L‐norleucine and L‐phenylalanine were 71 and 64%, respectively. The optical purity can be increased with continued recrystallization. The dansyl‐D‐leucine isomer was obtained in the mother liquor with an optical purity of 54–93% depending on experimental conditions. The optical purities obtained for D‐norleucine and D‐phenylalanine were 72 and 58%. The optical purity of the isomer depended on the molar ratio of host:guest and the pH value of the solution. Optimum enrichment of both enantiomers was achieved with host:guest ratios of 2 : 1 and 3 : 1. Although maximum crystalline yield of the dansyl‐leucine/CD inclusion complex was obtained at a pH of 3.5, optical purity of both enantiomers was less than that obtained at other pHs. The influence of the molar ratio of host:guest and the pH value of the solution are discussed. This method is suitable for large‐scale enantiomeric separations.
A vivid model of chiral recognition
Authors: Meyer Veronika R. , Rais Maya 
Published: January 2005

AbstractHands can be used to demonstrate the three‐point model of chiral recognition. The points of attachment are thumb, forefinger, and middle finger. This vivid model has the advantages of simplicity, perspicuity, and availability at any time, although two persons are necessary. It can be shown that two interactions are not sufficient for chiral recognition but that three attractive or two attractive and one repulsive attraction are needed. It can also be used to explain some possibilities of weakening or elusion of the three‐point model.
Stereoselectivity at muscarinic receptor subtypes: observations with the enantiomers of phenglutarimide
Authors: Lambrecht Günter , Feifel Roland , Mutschler Ernst 
Published: January 2005

AbstractThe affinity of the enantiomers of phenglutarimide at three muscarinic receptor subtypes was examined in vitro using field‐stimulated rabbit vas deferens (M1 receptors) and guinea pig atria (M2α receptors) and ileum (M2β receptors). Extremely high stereoselectivity was observed and higher affinities (up to 6000‐fold) were found for the (+)‐S‐enantiomer. The stereoselectivity ratios were different at the three subtypes, and the stereochemical demands made by the muscarinic receptors were most stringent at M1 receptors. (+)‐(S)‐Phenglutarimide was found to be a potent M1‐selective antagonist (pA2 at M1 = 8.53). Its receptor selectivity profile is qualitatively similar to that of pirenzepine. (−)‐(R)‐Phenglutarimide showed no comparable discriminatory properties.
The development of concepts of chiral discrimination
Authors: Mason Stephen F. 
Published: January 2005

AbstractPasteur's conjecture (1860) that biomolecular homochirality arose from a chiral natural force as yet inaccessible in the laboratory was supplanted by Fischer's (1894) “key and lock” hypothesis of stereoselection in enantiomer to diastereomer conversions, whether in the laboratory or in living organisms. Elaborations of the “key and lock” hypothesis by Haldane (1930) and Pauling (1948) have been illustrated and supported with modification by X‐ray diffraction crystal structures of enzyme–substrate complexes over the past quarter century.Two types of mechanism for the product diastereoselectivity in the reactions of an enantiomer with an achiral reagent, early proposed, have recent support: one proposes a quasidiastereomeric structure for the enantiomer attacked in the ground state, the other for the corresponding transition state of the reaction. Approaches to the differential biological activity of two enantiomers postulate either the complete binding of each isomer to a chiral receptor site, resulting in diastereomeric complexes with inequivalent bioactivities, or the differential binding of the two isomers to a set of three sites, with which only one isomer is sterically congruent.Biochemical homochirality, based on the chiral stereoselectivity of both biosynthetic and metabolic reactions, derives from the evolutionary pressure for a progressive enhancement of the kinetic efficiency and economy of those reactions. Recently Pasteur has been vindicated in part, and the problem of the original prebiotic enantiomeric excess left outstanding by Fischer has been solved. The unification of the electromagnetic with the weak interaction provided a universal chiral natural force, the electroweak interaction, which favours the chiral series selected during the course of biochemical evolution, both the D‐sugars and the L‐amino acids.
Species differences in the chirality of the carbonyl reduction of [14C] fenofibrate in laboratory animals and humans
Authors: Weil Andre , Caldwell John , Guichard Jean‐Pierre , Picot Gerard 
Published: January 2005

AbstractThe prochiral carbonyl group of fenofibrate (isopropyl 2‐[4‐(4‐chlorobenzoyl)phenoxy]‐2‐methyl propionate) is reduced during its metabolism giving rise to a chiral secondary alcohol, “reduced fenofibric acid.” Chiral and diastereomeric HPLC methods have been developed for the determination of its enantiomeric composition and these have been applied to the measurement of the “reduced fenofibric acid” enantiomers in urine of rats, guinea pigs, dogs, and human volunteers given [14C]fenofibrate. In the three animal species, the reduction is markedly enantioselective for the (–)‐isomer, the enantiomeric ratios (–/ +) being 95:5. This was not due to differences in the excretion of the enantiomers, since when racemic “reduced fenofibric acid” was given to rats it was recovered in the urine with the same enantiomeric composition as the dose form. In humans the ratio was 52:48 showing the lack of stereoselectivity of reduction in this species.
Separation and quantitation of (R)‐ and (S)‐atenolol in human plasma and urine using an α1‐AGP column
Authors: Enquist Märit , Hermansson Jörgen 
Published: January 2005

AbstractA method for the determination of (R)‐ and (S)‐atenolol in human plasma and urine is described. The enantiomers of atenolol are extracted into dichloromethane containing 3% heptafluorobutanol followed by acetylation with acetic anhydride at 60°C for 2 h. The acetylated enantiomers were separated on a chiral α1‐AGP column. Quantitation was performed using fluorescence detection. A phosphate buffer pH 7.1 (0.01 M phosphate) containing 0.25% (v/v) acetonitrile was used as mobile phase. The described procedure allows the detection of less than 6 ng of each enantiomer in 1 ml plasma. The relative standard deviation is 4.4% at 30 ng/ml of each enantiomer in plasma. The plasma concentration of (R)‐ and (S)‐ atenolol did not differ significantly in two subjects who received a single tablet of racemic atenolol. The R/S ratio of atenolol in urine was ∼ 1.
(−)‐(S)‐Flunoxaprofen and (−)‐(S)‐naproxen isocyanate: Two new fluorescent chiral derivatizing agents for an enantiospecific determination of primary and secondary amines
Authors: Martin E. , Quinke K. , Spahn H. , Mutschler E. 
Published: January 2005

AbstractThe synthesis and analytical testing of two new fluorescent chiral derivatizing agents (−)‐(S)‐flunoxaprofen and (−)‐(S)‐naproxen isocyanate, is described. In a few simple steps the free carboxylic acids [(S)‐flunoxaprofen and (S)‐naproxen] are activated with ethyl chloroformate/sodium azide and transformed to the corresponding isocyanates. The crystalline reaction products display high enantiomeric and chemical purity and stability. The direction of the optical rotation of both substances is inverse to that of the corresponding carboxylic acids. At ambient temperature the reagents swiftly react with primary and secondary amines, yielding highly fluorescent ureas. The applicability of the two reagents for the resolution of racemic amines was tested with a number of pharmaceuticals (antiarrhythmics, β‐adrenergic antagonists, calcium channel blockers, centrally acting antidepressants). The diastereoisomeric derivatives were efficiently resolved and separated from side‐products by means of normal and reversed‐phase high‐performance liquid chromatography (HPLC). The use and sufficient sensitivity of the two reagents for pharmacokinetic studies were demonstrated with a determination of plasma levels of propranolol enantiomers after oral administration of the racemic drug [80 mg (R,S)‐propranolol‐HCl] to two volunteers.
The role of configuration and conformation in the binding of 2,3‐benzodiazepines to human serum albumin
Authors: Visy Julia , Simonyi Miklós 
Published: January 2005

Abstract2,3‐Benzodiazepines containing a centre of asymmetry at C‐5 possess both central and helical chiralities, and the solution of their racemates contains four molecular species. The binding of these compounds to human serum albumin (HSA) was studied by affinity chromatography. The binding strength depended both on the steric orientation of the 5‐ethyl substituent and on the conformation of the diazepine ring. Conformation P (defined by the positive sign of C‐1–N‐2‐N–3–C‐4 torsion angle) is favoured, while the quasiaxial orientation ‐of the 5‐ethyl substituent is not favoured by the albumin molecule.
Direct high‐performance liquid chromatographic separation of penbutolol enantiomers on a cellulose tris‐3,5‐dimethylphenyl carbamate chiral stationary phase
Authors: Aboul‐Enein Hassan Y. , Islam M. Rafiqul 
Published: January 2005

AbstractPenbutolol is a β‐adrenoceptor blocking agent, and it contains the clinically relevant (−)‐S‐enantiomer. It was reported that the (+)‐R‐enantiomer of penbutolol is pharmacologically 50 times less active than the (−)‐S‐isomer in β‐sympatholysis and without intrinsic sympathomimetic activity and refractory period in the heart muscle. Furthermore, the (+)‐R‐enantiomer does possess mutagenic activity.A high‐performance liquid chromatographic (HPLC) method is described for direct identification, stereochemical separation, and quantitation of (+)‐R‐enantiomer in the clinically used (−)‐S‐isomer. The method involves the use of cellulose tris‐3,5‐dimethylphenyl carbamate chiral stationary phase coated on silica gel (OD‐Chiralcel column). The capacity factors (k′) for the first eluted enantiomer and stereochemical separation factor (α) obtained were 1.32 and 1.98, respectively. The maximum stereochemical resolution factor (R) was 5.05. The method could be applied for optical purity determination of (−)‐(S)‐penbutolol in pharmaceutical formulation to detect for the presence of the undesirable (+)‐R‐enantiomer.
The stereochemical resolution of the enantiomers of aspartame on an immobilized α‐chymotrypsin hplc chiral stationary phase: The effect of mobile‐phase composition and enzyme activity
Authors: Jadaud Philippe , Wainer Irving W. 
Published: January 2005

AbstractThe enantioselective and diastereoselective resolutions of the stereoisomers of Nα‐aspartyl‐phenylalanine 1‐methyl ester (APME) have been accomplished on an HPLC chiral stationary phase based upon α‐chymotrypsin (the ACHT‐CSP) with observed enantioselectivities (α1) for the DL‐/LD‐enantiomers of as high as 29.17 and for the DD‐/LL‐enantiomers of as high as 28.97. In addition, the effect on the chromatographic retention of the APME stereoisomers of the activity of the ACHT and the composition of the mobile phase—structure of the anionic component, molarity, and pH—have been studied. The results of this study suggest that the aspartyl moiety and/or the aspartyl‐phenylalanine amide linkage play key roles in the observed enantioselectivity; the APME stereoisomers containing L‐phenylalanine, i.e., DL‐ and LL‐APME, bind at a different site in the ACHT molecule (the L‐Phe site) than the APME stereoisomers containing D‐phenylalanine (the D‐Phe site); and the observed enantioselectivity is a measure of the difference in the binding affinities at the two sites rather than the consequence of differential affinities at a single site.
Reversed‐Phase LC resolutions of chiral antiarrhythmic agents via derivatization with homochiral isothiocyanates
Authors: Gal Joseph , Meyer‐lehnert Sabine , Desai Daksha M. 
Published: January 2005

AbstractThe search for new antiarrhythmic agents has been intense, because the established drugs for the treatment of cardiac arrhythmias are neither uniformly effective nor well‐tolerated. Among the recently introduced new anti‐arrhythmic agents are tocainide (TOC), mexiletine (MEX), flecainide (FLE), and propafenone (PRO). Each of these drugs is a chiral amine used clinically as the racemic mixture. We have examined the high‐performance liquid chromatographic chiral resolution of the above four drugs via derivatization with homochiral derivatizing agents (HDAs). The amino functionality of the drugs was reacted with four homochiral isothiocyanates, 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyl isothiocyanate (TAGIT), (R)‐α‐methylbenzyl isothiocyanate (RAMBI), (S)‐1‐(1‐naphthyl)ethyl isothiocyanate (SNEIT), and (R)‐1‐(2‐naphthyl)ethyl isothiocyanate (RBEIT). Complete separation of the two peaks (resolution factor R = 1.5) was achieved with all four HDAs for TOC, with TAGIT, RBEIT, and RAMBI for MEX, with TAGIT and SNEIT for PRO, and only with TAGIT for FLE. SNEIT was used to develop analytical procedures for the determination of the enantiomeric composition of TOC in human urine and blood serum. The four HDAs offer several advantages over many other HDAs and should be useful in studies of enantioselective drug action and disposition.