bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of in ovo electroporation for the rapid analysis of neural‐specific murine enhancers
Authors: Timmer John , Johnson Jane , Niswander Lee 
Published: August 2002

AbstractSummary: The identification and characterization of DNA sequences necessary for proper gene expression have provided insights into gene regulation and generated tools useful for further experimentation. Studies of developmentally regulated genes have demonstrated how transcription factors interact at enhancers to generate restricted patterns of expression during embryogenesis. In vertebrates, the pursuit of such studies has relied on the generation of transgenic mice and thus has been limited by the time and expense required generating and characterizing these mice. The recently developed technique of in ovo electroporation allows the rapid introduction of exogenous DNA into developing chicken embryos. Here we have used this technique to introduce DNA containing murine enhancer/reporter constructs into cells of the chicken neural tube, resulting in appropriate expression of the reporter. This technique has the potential to greatly reduce the effort involved in the study of vertebrate enhancers. Furthermore, we have characterized factors such as timing of electroporation, concentration of DNA, and choice of basal promoters and found that they can influence the degree to which expression of enhancer constructs reflects endogenous gene expression. genesis 29:123–132, 2001. © 2001 Wiley‐Liss, Inc.
Developmental regulation of an instability element from the Drosophila fushi tarazu mRNA
Authors: Fontes Aparecida Maria , Riedl Ann , Jacobs‐Lorena Marcelo 
Published: August 2002

AbstractSummary: The Drosophila fushi tarazu (ftz) mRNA is one of the shortest‐lived metazoan mRNAs, and its instability is crucial for proper development of the embryo. Previously, we identified two cis‐acting elements that are required for ftz mRNA degradation, one within the 5′ one‐third and another in the 3′UTR of the message. Here we focus on the 3′UTR element termed FIE3 (ftz instability element in the 3′UTR). To investigate the developmental regulation of the FIE3‐dependent degrading activity we measured the abundance of an FIE3‐containing mRNA in ovaries, unfertilized eggs, and different larval and adult tissues. We found that FIE3‐degrading activity is present at all developmental stages and tissues examined, except in the ovary. Activation of the FIE3‐dependent mRNA decay is independent of fertilization because it could be triggered by egg activation. Finally, we provide evidence that mutation of conserved elements within FIE3 had no effect on mRNA instability. genesis 30:59–64, 2001. © 2001 Wiley‐Liss, Inc.
Imprinting defects in mouse embryos: stochastic errors or polymorphic phenotype?
Authors: Croteau Sylvie , Polychronakos Constantin , Naumova Anna K. 
Published: August 2002

AbstractSummary: Defects in expression of imprinted genes are believed to cause developmental abnormalities and play a role in carcinogenesis. To determine whether spontaneous imprinting defects may occur in mouse embryos, we studied the expression of two imprinted genes H19 and Igf2 in individual postimplantation 7.5 d.p.c. and 8.5 d.p.c. embryos. Biallelic expression of H19 was found in 1.6% of the embryos, whereas biallelic expression of Igf2 was found in 0.5% of the embryos. The loss of H19 imprinting (LOI) observed in a small fraction of early postimplantation embryos may be purely stochastic. Alternatively, since we never observed it in an inbred background, it may depend on genetic factors acting in trans. Either mechanism could explain the occurrence of polymorphic imprinting as well as the genesis of sporadic imprinting defects, including cancer. The frequency of LOI of H19 was higher than the incidence of sporadic imprinting disorders in humans (about 1 in 20,000). This contradiction may be explained by different incidence of imprinting errors in different imprinted regions of the genome, in different species, or by loss of the majority of nonmosaic embryos with imprinting defects before birth. genesis 31:11–16, 2001. © 2001 Wiley‐Liss, Inc.
Is peak height sufficient?
Authors: Siegmund David 
Published: August 2002

AbstractThe suggestion that more power can be obtained from a genome scan by consideration of “peak width” in addition to “peak height” has been controversial. Regarding this question from the viewpoint of smoothing, one finds that to the extent that smoothing increases the informativeness of individual markers it is possible to obtain increased power; but for markers that are fully informative the value of smoothing is questionable. Genet. Epidemiol. 20:403–408, 2001. © 2001 Wiley‐Liss, Inc.
Lod scores for gene mapping in the presence of marker map uncertainty
Authors: Stringham Heather M. , Boehnke Michael 
Published: August 2002

AbstractMultipoint lod scores are typically calculated for a grid of locus positions, moving the putative disease locus across a fixed map of genetic markers. Changing the order of a set of markers and/or the distances between the markers can make a substantial difference in the resulting lod score curve and the location and height of its maximum. The typical approach of using the best maximum likelihood marker map is not easily justified if other marker orders are nearly as likely and give substantially different lod score curves. To deal with this problem, we propose three weighted multipoint lod score statistics that make use of information from all plausible marker orders. In each of these statistics, the information conditional on a particular marker order is included in a weighted sum, with weight equal to the posterior probability of that order. We evaluate the type 1 error rate and power of these three statistics on the basis of results from simulated data, and compare these results to those obtained using the best maximum likelihood map and the map with the true marker order. We find that the lod score based on a weighted sum of maximum likelihoods improves on using only the best maximum likelihood map, having a type 1 error rate and power closest to that of using the true marker order in the simulation scenarios we considered. Genet. Epidemiol. 21:31–39, 2001. © 2001 Wiley‐Liss, Inc.
Palaeoclimate indicators (clay minerals, calcareous nannofossils, stable isotopes) compared from two successions in the late Jurassic of the Volga Basin (SE Russia)
Authors: Ruffell A. H. , Price G. D. , Mutterlose J. , Kessels K. , Baraboshkin E. , Gröcke D. R. 
Published: August 2002

AbstractA study of clay mineral and calcareous nannofossil abundances in late Jurassic–early Cretaceous sediments from the Volga Basin, SE Russia, is presented. From these results, we are able to compare some general patterns of mineralogical and palaeontological change for the Volga Basin to the palaeoclimate models developed for northern Europe and beyond. The two successions examined comprise calcareous mudstones with black organic‐rich shale horizons, overlain by a series of phosphatic silty sands. Clay mineralogical results show a progressive decrease in kaolinite and the concomitant increase of smectite and illite through the middle Volgian, followed by an abrupt increase in kaolinite in the late Volgian. The clay mineral evidence suggests increasing aridity at the end of the Jurassic, similar, in part, to many western European successions. Because of differential settling of clay minerals, superimposed upon this possible climatic signature is likely to be the effect of relative sea‐level change. Calcareous nannofossil analysis from a single section reveals a shift through the middle Volgian from low nutrient, warm water assemblages dominated by Watznaueria to cooler surface water and high nutrient assemblages dominated by Biscutum constans. These observations suggest that increased aridity is also associated with climatic cooling. Black shales are associated with increased productivity, higher sea levels and increases in smectite content. Hence, periods of low (chemical) hinterland weathering during semi‐arid conditions are paradoxically associated with relatively nutrient‐rich waters, and organic‐rich shales. Comparison of published carbon and oxygen stable isotope results from this and other sections to the clay mineral and nannofossil data confirms the palaeoclimatic interpretation. This study significantly improves the published biostratigraphically constrained clay mineral database for this time period, because other European and North American successions are either non‐marine (and thus poorly dated), absent (through penecontemporaneous erosion) or condensed. Copyright © 2002 John Wiley & Sons, Ltd.
Inhibition of store‐operated Ca2+ influx by acidic extracellular pH in cultured human microglia
Authors: Khoo Clarence , Helm Jeffrey , Choi Hyun B. , Kim Seung U. , McLarnon James G. 
Published: August 2002

AbstractThe effects of extracellular acidification on Ca2+‐dependent signaling pathways in human microglia were investigated using Ca2+‐sensitive fluorescence microscopy. Adenosine triphosphate (ATP) was used to elicit Ca2+ responses primarily dependent on the depletion of intracellular endoplasmic reticulum (ER) stores, while platelet‐activating factor (PAF) was used to elicit responses primarily dependent on store‐operated channel (SOC) influx of Ca2+. The duration of transient responses induced by ATP was not significantly different in standard physiological pH 7.4 (mean duration 30.2 ± 2.5 s) or acidified pH 6.2 (mean duration 31.7 ± 2.8 s) extracellular solutions. However, the time course of the PAF response at pH 7.4 was significantly reduced by 87% with external pH at 6.2. These results suggest that acidification of extracellular solutions inhibits SOC entry of Ca2+ with little or no effect on depletion of ER stores. Changes of extracellular pH over the range from 8.6 to 6.2 during the development of a sustained SOC influx induced by PAF resulted in instantaneous modulation of SOC amplitude indicating a rapidly reversible effect of pH on this Ca2+ pathway. Whole‐cell patch clamp recordings showed external acidification blocked depolarization‐activated outward K+ current indicating cellular depolarization may be involved in the acid pH inhibition. Since SOC mediated influx of Ca2+ is strongly modulated by membrane potential, the electrophysiological data suggest that acidification may act to inhibit SOC by cellular depolarization. These results suggest that acidification observed during cerebral ischemia may alter microglial responses and functions. GLIA 36:22–30, 2001. © 2001 Wiley‐Liss, Inc.
Vitamin B12 in primary health care and geriatrics—attitudes, knowledge and competence
Authors: Lökk Johan , Nilsson Mats , Norberg Bo , Hultdin Johan , Sandström Herbert , Westman Göran 
Published: August 2002

AbstractObjectivesThe objective of the study was to test attitudes, knowledge and competence of Swedish general practitioners and geriatricians concerning B12‐associated problems in 1998.MethodsPostal questionnaires were sent to a random sample of 485 GPs and a total sample of 613 geriatricians. The response rates were 70% in the GP group and 69% in the geriatrician group. The questionnaire contained 24 statements to be evaluated by a visuo‐analogue scale.ResultsThere were small numerical differences between the two physician groups. The geriatricians were more aware of risk groups for B12 deficiency. GPs were less categorical concerning low hit rate in the laboratory testing of clinical conclusions. There were statistical differences in both directions for statements on pitfalls in laboratory diagnostics. GPs were somewhat less prone to give risk groups prophylactic B12 therapy.ConclusionsGPs and geriatricians appeared to be familiar with the current debate on B12‐associated problems, suggesting that health care quality will be unaffected by patient transfer from hospital care to primary health care. Copyright © 2001 John Wiley & Sons, Ltd.
C‐phosphorylation of N‐arylpyrroles
Authors: Ivonin Sergey P. , Tolmachev Andrew A. , Pinchuk Alexander M. 
Published: August 2002

AbstractPhosphorylation of N‐arylpyrroles with phosphorus tribromide proceeds regioselectively at the position 2 of the heterocyclic system. A 2‐to‐3 migration of the dibromophosphino group has been discovered, with its ease depending on the electronic nature of a substituent on the phenyl ring, solvent polarity, and the presence of pyridine hydrobromide in the reaction mixture. Further phosphorylation of 2‐ and 3‐monophosphorylated N‐arylpyrroles regioselectively involves the respective positions 4 and 5 of the heterocycle and is governed by the electron‐acceptor effect of the phosphorus‐containing substituent. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:223–228, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10012
The reaction of heteroaroyl‐substituted heterocyclic ketene aminals with 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyl azide
Authors: Yang Qiang , Li Zhan‐Jiang , Chen Xiao‐Min , Huang Zhi‐Tang 
Published: August 2002

AbstractThe reaction of heteroaroyl‐substituted heterocyclic ketene aminals with 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyl azide was investigated and a series of potential bioactive compounds, 1‐glucopyranosyl‐4‐heterocyclic‐5‐heteroaryl‐1,2,3‐triazoles, were obtained in good yields. Both the reaction rate and the yield were strongly affected by the heteroaryl and heterocyclic groups. In order to improve their water solubility, the deprotection of 1‐glucopyranosyl‐4‐heterocyclic‐5‐heteroaryl‐1,2,3‐triazole was carried out. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:242–247, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10023
Facile stereoselective syntheses of aryl substituted α,β‐unsaturated esters containing a trifluoromethyl group
Authors: Pan Rui‐Qi , Wang Ping‐An , Deng Min‐Zhi 
Published: August 2002

AbstractThe Suzuki‐type cross‐coupling reaction of arylboronic acids 3 with ethyl (Z)‐3‐iodo‐4,4,4‐trifluoro‐2‐butenoate 2, which was generated by hydroiodination of available ethyl 4,4,4‐trifluoro‐2‐butynoate 1, to afford ethyl (E)‐3‐aryl‐4,4,4‐trifluoro‐2‐butenoates 4, was studied for the first time. It was found that under the optimum conditions the cross‐coupling reaction could readily give 4 as the sole E‐isomer in 76–91% yields. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:287–290, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10032
A tandem reaction of 4‐bromoalkyl aldehydes with sodium azide: Synthesis of 5,6,7,7a‐tetrahydro‐pyrrolo[1,2‐d]‐[1.2.3.4]oxatriazole
Authors: Ma Yuan 
Published: August 2002

Abstract5,6,7,7a‐Tetrahydro‐pyrrolo[1,2‐d]‐[1.2.3.4]oxatriazoles were synthesized through a nucleophilic substitution–cycloaddition tandem reaction of 4‐bromoalkyl aldehydes with sodium azide. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:307–309, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10035
Desilylation and conversion of trimethylsilylmethyl epoxides into ketones under the influence of a bulky base
Authors: Ma Yuan 
Published: August 2002

AbstractTrimethylsilylmethyl epoxides were converted into ketones through a desilylation, epoxide ring‐opening, and rearrangement reaction under the influence of a bulky base in the presence of 18‐crown‐6. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:310–315, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10036
Amino acids in the syntheses of heterocyclic systems: Syntheses and radiostability of novel biologically active triazoles containing the sulfonamide moiety
Authors: El‐Sharief A. M. Sh. , Ghorab M. M. , El‐Gaby M. S. A. , Mohamed Sh. I. , Ammar Y. A. 
Published: August 2002

AbstractA number of novel triazoles 2a–f, 4, 9, 10, 12, 15; triazolothiadiazoles 6, 8, 11, 16; triazolothiadiazine 5; and triazolotriazine 14 were synthesized and characterized by elemental analyses and spectral data. Six of the compounds showed antifungal activity compared with the fungicide Mycostatine. Radiosterilization of the biologically active compounds 4, 8, 9b, and 10 in the dry state may prove to be applicable at the sterile dose 25 kGy. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:316–323, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10037
Rhodium‐catalyzed coupling reactions of β‐ or α,β‐substituted vinylpyridines with alkenes via CH bond activation
Authors: Lim Yeong‐Gweon , Kang Jung‐Bu , Lee Kieseung , Kim Yong Hae 
Published: August 2002

Abstractβ‐ or α,β‐Substituted vinylpyridines react with 3,3‐dimethylbut‐1‐ene in the presence of Wilkinson catalyst [RhCl(PPh3)3] to give the corresponding alkylated products along with unusually isomerized products. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:346–350, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10045
Regiocontrolled reactions of allylphosphonates: Syntheses of 1‐[(3‐methoxycarbonyl)‐allyl]‐vinylphosphonates and 3‐methoxycarbonyl‐1,3‐dienylphosphonates
Authors: Shen Yanchang , Jiang Guo‐Fang 
Published: August 2002

Abstract‘Regiocontrolled syntheses of 3‐methoxycarbonyl‐1,3‐dienylphosphonates and 1‐[(3‐methoxycarbonyl)‐allyl]vinylphosphonates by using different conditions are described. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:373–376, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10050
Syntheses of 2‐alkylthio‐1,3‐thiazine derivatives from S‐alkyldithiocarbamates and α,β‐unsaturated ketones
Authors: Koketsu Mamoru , Okumura Miki , Ishihara Hideharu 
Published: August 2002

AbstractVarious 2‐alkylthio‐1,3‐thiazine derivatives were synthesized by the reactions of S‐alkylthiocarbamates with α,β‐unsaturated ketones in the presence of BF3 · Et2O. The thiazine was converted into two isomeric dehydrated products in the presence of a Lewis acid. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:377–379, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10055
Planarity of acetamides, thioacetamides, and selenoacetamides: Crystal structure of N,N‐dimethylselenoacetamide
Authors: Niu Shuqiang , Li Guang Ming , Zingaro Ralph A. , Reibenspies Joseph H. , Ichiye Toshiko 
Published: August 2002

AbstractThe planarity of acetamides 1a–3a, thioacetamides 4a–6a, and selenoacetamides 7a–9a, R1R2NC(=E)CH3 where E = O, S, Se, and R1, R2 = H or CH3, was investigated using theoretical calculations at the density functional theory (DFT) level. The calculations showed that the methyl substitution on nitrogen and the change from the amide moiety (NCO) to NCS or NCSe group increased the double bond character of the NC bond. In other words, the planarity of these compounds (1a–9a) increases in the order NH2 < NHCH3 < N(CH3)2 and O < S < Se. The calculations of bending energy suggest that the planar geometry represents the lowest energy conformation for all compounds investigated in this work. N,N‐Dimethyl‐selenoacetamide (9a), (CH3)2NC(Se) CH3, has the largest bending energy of 10.37 kcal/mol, which suggests that it possesses the greatest planarity among the compounds 1a–9a. However, the solid phase molecular structure of 9a was found to be slightly nonplanar by X‐ray crystallography. The slight nonplanarity observed experimentally is very likely the consequence of intermolecular interactions arising within the crystal packing. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:380–386, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10056
Pyridine‐facilitated phenylselenoetherification of some tertiary alkenols
Authors: Mojsilovic Biljana M. , Bugaric Zorica M. 
Published: August 2002

AbstractAn improved procedure for intramolecular cyclization of tertiary alkenols using benzeneselenyl halides has been developed. We found that cyclization can be facilitated by pyridine. Thus, in the presence of an equimolar amount of pyridine, a chemospecific reaction could be observed that resulted in formation of corresponding cyclic ethers, and quantitative yields were achieved instantaneously under extremely mild experimental conditions. The effect of the halide ion of the selenylating reagent is not significant, both halides generally giving equal results © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:475–479, 2001
New chiral macrocyclic phosphoramidate self‐associated by an intermolecular N–H ··· O = P hydrogen bond
Authors: Du Da‐Ming , Hua Wen‐Ting , Wang Zhe‐Ming , Yan Chun‐Hua 
Published: August 2002

AbstractNew macrocyclic chiral phosphoramidates containing 2,5‐diaryl‐1,3, 4‐oxadiazole and L‐alanine methyl ester units were synthesized by a convenient one‐pot procedure, X‐ray analysis of one chiral macrocycle shows that the phosphoramidate molecules are self‐associated by intermolecular N–H ··· O = P hydrogen bonds, the layer stacking along the b axis forming channels parallel to the b axis. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:480–484, 2001
Syntheses of new conformationally constrainedS‐[2‐[(1‐iminoethyl)amino] ethyl]homocysteine derivatives as potential nitric oxide synthase inhibitors
Authors: Wang Lijuan J. , Grapperhaus Margaret L. , Pitzele Barnett S. , Hagen Timothy J. , Fok Kam F. , Scholten Jeffrey A. , Spangler Dale P. , Toth Mihaly V. , Jerome Gina M. , Moore William M. , Manning Pamela T. , Sikorski James A. 
Published: August 2002

AbstractThe efficient syntheses of two new types of conformationally constrained S‐[2‐[(1‐iminoethyl)amino]ethyl]homocysteine derivatives, 1‐amino‐3‐[2[(1‐iminoethyl)amino]ethylthio]cyclobutane carboxylic Acid (5) and (4S)‐4‐[[2‐[(1‐Iminoethyl)amino]ethyl]thio]‐L‐proline (6), are reported. These molecules represent the first attempts to probe conformational constraint near the α‐amino acid moiety of known homocysteine‐based inhibitors of nitric oxide synthase. Targets5and6were evaluated as potential inhibitors of the three human isoforms of nitric oxide synthase. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:77–83, 2002; DOI 10.1002/hc.1109
Reconsideration of discharge data to measure competition in the hospital industry
Authors: Nauenberg Eric , Andrijuk Yuri , Eisinger Matthew 
Published: August 2002

AbstractEconomists have long used state‐collected discharge data to construct Hirschman–Herfindahl (HH) indices measuring hospital competition. Since data are collected to determine the facility providing the service rather than ownership, the difference between the number of reporting facilities and the number of competitors has grown over time due to mergers and networking activities. Consequently, the validity of the discharge HH methodology, as currently employed, is in doubt. Comparing the annual census of New York state acute‐care hospitals by the State and the American Hospital Association (AHA), we find that it is increasingly important to account for changes in ownership when constructing such indices. Copyright © 2001 John Wiley & Sons, Ltd.
Reply to: econometric issues in testing the age neutrality of health care expenditure
Authors: Zweifel Peter , Felder Stefan , Meier Markus 
Published: August 2002

AbstractSalas and Raftery allege that in our paper, (1) remaining life expectancy is an endogenous explanatory variable of health care expenditure and (2) the parameter designed to correct for sample selection bias in fact represents a hidden relationship between health care expenditure and age. We argue that claim (1) is not supported by the available empirical evidence, while claim (2) seems to derive from a too cursory reading of our paper. Copyright © 2001 John Wiley & Sons, Ltd.