bluuebunny/crossref_metadata_2025_split huggingface dataset:
Base‐Pairing Systems Related to TNA Containing Phosphoramidate Linkages: Synthesis of Building Blocks and Pairing Properties
Authors: Ferencic Mathias , Reddy Goverdhan , Wu Xiaolin , Guntha Sreenivasulu , Nandy Jyoti , Krishnamurthy Ramanarayanan , Eschenmoser Albert 
Published: July 2004

AbstractAs part of a project that aims at screening TNA‐related oligonucleotide systems in which threose backbone units may have some or all of their oxygen functions replaced by nitrogen, two TNA analogs containing (2′NH)‐ and (3′NH)‐phosphoramidate groups, respectively, in place of phosphodiester groups were synthesized. They show base‐pairing properties that are very similar to those of TNA itself. We also synthesized 2′,3′‐diamino analogs of α‐L‐threofuranosyl mononucleosides, yet attempts to convert them to TNA analogs containing phosphodiamidate linker groups were not successful. Such 2′,3′‐diamino derivatives of threofuranosyl nucleosides may be of interest, however, as building blocks of TNA analogs that contain non‐phosphorous linker groups.
Reduction of carbon tetrachloride‐induced nephropathy by melatonin administration
Authors: Ogeturk Murat , Kus Ilter , Kavakli Ahmet , Oner Jale , Kukner Aysel , Sarsilmaz Mustafa 
Published: July 2004

AbstractThe aim of this study was to investigate possible protective effects of melatonin on carbon tetrachloride (CCl4)‐induced renal damage in rats. A total of 24 animals were divided into three equal groups: the control rats received pure olive oil subcutaneously, rats in the second group were injected with CCl4 (0.5 ml kg−1, s.c. in olive oil) and rats in the third group were injected with CCl4 (0.5 ml kg−1) plus melatonin (25 mg kg−1, s.c. in 10% ethanol) every other day for 1 month. At the end of the experimental period, the animals were sacrificed and blood samples were collected. The kidneys were removed and weighed. Urea and creatinine levels were determined in blood samples. Histopathological examination of the kidney was performed using light microscopic methods. Administration of CCl4 significantly increased relative kidney weight (g per 100 g body weight) and decreased serum urea levels compared to controls (p < 0.01). Melatonin treatment significantly (p < 0.01) reduced relative kidney weight, and it produced a statistically equal (p = 0.268) relative weight with the kidneys of control rats. CCl4 administration alone also caused histopathologically prominent damage in the kidney compared to the control group. Glomerular and tubular degeneration, interstitial mononuclear cell infiltration and fibrosis, vascular congestion around the tubules, and interstitial haemorrhage in perivascular areas were observed in the renal cortex and cortico‐medullary border. However, the affect of CCl4 on the medulla was limited. Melatonin provided protection against CCl4‐induced renal toxicity as was evident by histopathological evaluation. In view of the present findings, it is suggested that melatonin protects kidneys against CCl4 toxicity. Copyright © 2004 John Wiley & Sons, Ltd.
Learning outcomes for the twenty‐first century: Cultivating student success for college and the knowledge economy
Authors: Miles Cindy L. , Wilson Cynthia 
Published: July 2004

AbstractThis chapter provides an overview of the League for Innovation in the Community College's project on learning outcomes. The 21st Century Learning Outcomes Project was a three‐year project involving sixteen diverse community colleges that supported the development of practices for assessing and using student learning outcomes to improve student success.
Meeting the challenges of assessing student learning outcomes
Authors: Friedlander Jack , Serban Andreea M. 
Published: July 2004

AbstractAlthough community colleges have made significant strides in assessing student learning outcomes, there are a number of significant challenges that need to be addressed in order to realize fully the anticipated benefits of these efforts. This chapter identifies these major challenges and provides specific suggestions that can be used by community colleges, state and accrediting agencies, and universities to facilitate the development, implementation, and continued support of student learning outcomes assessment initiatives that will increase student learning and achievement.
Molecular Structure of Proline
Authors: Allen Wesley D. , Czinki Eszter , Császár Attila G. 
Published: July 2004

AbstractThe molecular structures of the two lowest‐energy conformers of proline, Pro‐I and Pro‐II, have been characterized by ab initio electronic structure computations. An extensive MP2/6‐31G* quartic force field for Pro‐I, containing 62 835 unique elements in the internal coordinate space, was computed to account for anharmonic vibrational effects, including total zero‐point contributions to isotopomeric rotational constants. New re and improved r0 least‐squares structural refinements were performed to determine the heavy‐atom framework of Pro‐I, based on experimentally measured (A. Lesarri, S. Mata, E. J. Cocinero, S. Blanco, J. C. Lopez, J. L. Alonso, Angew. Chem. 2002, 114, 4867; Angew. Chem. Int. Ed. 2002, 41, 4673) rotational constant sets of nine isotopomers and our ab initio data for structural constraints and zero‐point vibrational (ZPV) shifts. Without the ab initio constraints, even the extensive set of empirical rotational constants cannot satisfactorily fix the molecular structure of the most stable conformer of proline, a 17‐atom molecule with no symmetry. After imposing the ab initio constraints, excellent agreement between theory and experiment is found for the heavy‐atom geometric framework, the root‐mean‐square (rms) residual of the empirical rotational constant fit being cut in half by adding ZPV corrections. The most significant disparity, about 0.07 Å, between the empirical and the best ab initio structures, concerns the r(N⋅⋅⋅H) distance of the intramolecular hydrogen bond. Some of the experimental quartic centrifugal distortion constants assigned to Pro‐II have been corrected based on data obtained from a theoretical force field.
Regio‐ and Stereospecific Cleavage of Silyl‐ and Disilylepoxides with Lithium Diphenylphosphide
Authors: Cuadrado Purificación , González‐Nogal Ana M. , Sarmentero M. Angeles 
Published: July 2004

AbstractUnsubstituted or α‐ and β‐C‐substituted silylepoxides react stereospecifically with lithium diphenylphosphide, optionally followed by methylation, to give vinylphosphonium iodides or vinylphosphine oxides resulting from α‐opening and silyl enol ethers, vinylsilanes or α‐hydroxysilanes by β‐opening. On the other hand, α,β‐ or α,α‐disilylepoxides afforded β‐silyl vinylphosphine oxides or α‐silylated silyl enol ethers by α‐ and β‐cleavage, respectively. All compounds are interesting synthons in organic chemistry.
First Total Synthesis of Hormaomycin, a Naturally Occurring Depsipeptide with Interesting Biological Activities
Authors: Zlatopolskiy Boris D. , de Meijere Armin 
Published: July 2004

AbstractSome unique features were disclosed during the structure elucidation of the cyclic depsipeptide hormaomycin (1), first isolated in 1989 from aStreptomyces griseoflavusstrain and found to have quite an interesting spectrum of biological activities. Besides one residue of the proteinogenic amino acid isoleucine [(S)‐Ile], it contains two units of 3‐methylphenylalanine [(βMe)Phe], one of (2R)‐allo‐threonine [a‐Thr] as well as two moieties of 3‐(trans‐2‐nitrocyclopropyl)alanine [(3‐Ncp)Ala] and one of 4‐(Z)‐propenylproline [(4‐PE)Pro]. The latter two have never been found in any natural product before. The side chain of1is terminated with the residue of 5‐chloro‐1‐hydroxypyrrole‐2‐carboxylic acid [Chpca]. This first synthetic access to hormaomycin1will make it possible to prepare structural analogues of this interesting natural depsipeptide in order to elucidate structure–activity relationships and the biologically active minimal unit.
Lead and Mercury Sensing by Calixarene‐Based Fluoroionophores Bearing Two or Four Dansyl Fluorophores
Authors: Métivier Rémi , Leray Isabelle , Valeur Bernard 
Published: July 2004

AbstractA detailed study on the photophysical and complexing properties of calixarenes bearing two and four dansyl derivatives (Calix‐DANS2 and Calix‐DANS4) in a CH3CN/H2O mixture (60:40 v/v) is reported. Calix‐DANS2 shows a high selectivity towards Hg2+ over interfering cations (Na+, K+, Ca2+, Cu2+, Zn2+, Cd2+ and Pb2+) and a sensitivity in the 10−7 mol L−1 concentration range. The complexation of mercury ion induces a strong fluorescence quenching due to a well‐defined electron transfer process from the fluorophore to the metal center. Calix‐DANS4 exhibits an extremely high affinity for Pb2+ with a high selectivity over various competing ions. The unprecedented detection limit (4 μg L−1) is fully compatible with the level defined by the World Health Organisation. The affinity of Calix‐DANS4 for Pb2+ can be rationalized by the activation of the inert pair of electrons on Pb2+. The number of fluorophores involved in the complexation can be determined from a careful time‐resolved fluorescence characterization.
ULTRAMINE: A High‐Capacity Polyethylene–Imine‐Based Polymer and Its Application as a Scavenger Resin
Authors: Roice Michael , Christensen Søren F. , Meldal Morten 
Published: July 2004

AbstractThe synthesis of a novel high‐loading polyethylene–imine resin (ULTRAMINE) is described, and its application as a scavenger resin in various acylation reactions is demonstrated. The inverse suspension polymerization technique was used for the synthesis of well‐defined spherical polymer beads. Polymer beads with different cross‐linking densities were synthesized according to the degree of acryloylation of the polyethylene–imine polymer. The resin was characterized by various spectroscopic techniques. The size, shape, and morphological features of the resin were demonstrated by microscopy. The resin showed excellent swelling properties in both polar and nonpolar solvents. The chemical stability of the resin in various reagents and solvents was investigated and monitored by IR spectroscopy. The mechanical stability of the beads was determined by a single‐bead compressive experiment. The ULTRAMINE beads can be used as an excellent scavenger for excess acylating reagent, as demonstrated for a variety of reactions. ULTRAMINE‐red resin was derived from ULTRAMINE through exhaustive reduction of the amide carbonyl groups to yield an all‐amine resin.
Analysis of UV‐excited fluorochromes by flow cytometry using near‐ultraviolet laser diodes
Authors: Telford William G. 
Published: July 2004

AbstractIntroductionViolet laser diodes have become common and reliable laser sources for benchtop flow cytometers. While these lasers are very useful for a variety of violet and some ultraviolet‐excited fluorochromes (e.g., DAPI), they do not efficiently excite most UV‐stimulated probes. In this study, the next generation of InGaN near‐UV laser diodes (NUVLDs) emitting in the 370–375‐nm range have been evaluated as laser sources for cuvette‐based flow cytometers.MethodsSeveral NUVLDs, ranging in wavelength from 370 to 374 nm and in power level from 1.5 to 10 mW, were mounted on a BD Biosciences LSR II and evaluated for their ability to excite cells labeled with the UV DNA binding dye DAPI, several UV phenotyping fluorochromes (including Alexa Fluor 350, Marina Blue, and quantum dots), and the fluorescent calcium chelator indo‐1.ResultsNUVLDs at the 8–10‐mW power range gave detection sensitivity levels comparable to more powerful solid‐state and ion laser sources, using low‐fluorescence microsphere beads as measurement standards. NUVLDs at all tested power levels allowed extremely high‐resolution DAPI cell cycle analysis, and sources in the 8–10‐mW power range excited Alexa Fluor 350, Marina Blue, and a variety of quantum dots at virtually the same signal‐to‐noise ratios as more powerful UV sources.ConclusionsThese evaluations indicate that near‐UV laser diodes installed on a cuvette‐based flow cytometer performed nearly as well as more powerful solid‐state UV lasers on the same instrumentation, and comparably to more powerful ion lasers on a jet‐in‐air system, and. Despite their limited power, integration of these small and inexpensive lasers into benchtop flow cytometers should allow the use of flow cytometric applications requiring UV excitation on a wide variety of instruments. © 2004 Wiley‐Liss, Inc.
Effect of changing symbol rate on equalizer performance for band‐limited systems
Authors: Liu Hong‐Yu , Yen Rainfield Y. 
Published: July 2004

AbstractIn this work, the effect of changing symbol rate (or equivalently, symbol rate) on the equalizer performance for M‐ary PAM systems is investigated. We keep increasing the symbol rate (or equivalently, keep decreasing the symbol period) until a limit is reached. An effort is made to find this limit. In other words, we are investigating the possibility of increasing the symbol rate beyond the usual Nyquist rate. Since incessantly increasing the symbol rate will eventually produce channel spectrum null (almost null) which will render difficulties for equalization, decision‐feedback equalization combined with fractionally spaced sampling is used to overcome the difficulties. For a given channel bandwidth and a prescribed error probability, optimum symbol rates vs SNR are found so as to achieve maximum bit rates. Explanations are given for the resultant phenomena both analytically as well as by computer simulations. A theoretical channel model and a realistic twisted pair channel are used for demonstration. Important analytical expressions are given along with computer simulations to quantify performance results. Copyright © 2004 John Wiley & Sons, Ltd.
Effectiveness of progressive dose‐escalation of exenatide (exendin‐4) in reducing dose‐limiting side effects in subjects with type 2 diabetes
Authors: Fineman Mark S. , Shen Larry Z. , Taylor Kristin , Kim Dennis D. , Baron Alain D. 
Published: July 2004

AbstractBackgroundExenatide (exendin‐4) exhibits dose‐dependent glucoregulatory activity, but causes dose‐limiting nausea and vomiting. This study was designed to formally assess the possibility of inducing tolerance to the side effects of nausea and vomiting at therapeutic doses of exenatide, using a dose‐escalation methodology.MethodsIn this two‐arm, triple‐blind, multicenter study, 123 subjects with type 2 diabetes were enrolled and randomized; 99 (80.5%) of them completed the study. Subjects in the exenatide‐primed arm received subcutaneous exenatide, starting at 0.02 µg/kg three times a day (TID) and increasing in 0.02 µg/kg per dose increments every 3 days for 35 days. Subjects in the exenatide‐naive arm received placebo TID for 35 days. At the end of this 35‐day regimen, subjects in both arms received the same highest dose of exenatide (0.24 µg/kg TID) for 3 days. Thus, the exenatide‐naive arm received exenatide for the first time on Day 35.ResultsThe exenatide‐primed arm had a lower proportion of subjects experiencing nausea and vomiting in response to exposure to the highest dose of exenatide (27 vs 56% in the exenatide‐naive arm; p = 0.0018). Kaplan–Meier estimates of cumulative incidence were 0.28 in the exenatide‐primed arm, compared with 0.68 in the exenatide‐naive arm (p ≤ 0.001). As predicted by the study design, fewer subjects in the exenatide‐primed arm reported severe nausea (29%) and vomiting (10%) than those in the exenatide‐naive arm (48 and 31%, respectively). In the exenatide‐primed arm, fasting serum glucose progressively declined over the first 35 days of dosing, but was unchanged in the exenatide‐naive arm (placebo phase) during the same interval.ConclusionGradual dose‐escalation of exenatide successfully reduced the proportion of subjects experiencing dose‐limiting nausea and vomiting, with no loss of glucoregulatory activity, thus demonstrating the value of gradual dose‐escalation in mitigating the gastrointestinal side effects of exenatide. Copyright © 2004 John Wiley & Sons, Ltd.
Expression and function of integrin α4β1 and vascular cell adhesion molecule‐1 (VCAM‐1) during sympathetic innervation of the heart
Authors: Wingerd Kevin L. , Goodman Nichol L. , Leu Sergiu T. , Clegg Dennis O. 
Published: July 2004

AbstractThe interaction between the integrin α4β1 receptor on superior cervical ganglion (SCG) neurons and vascular cell adhesion molecule‐1 (VCAM‐1) in cardiac tissue has been implicated in proper development of the sympathetic innervation of the heart (Wingerd et al. [2002] J Neurosci 22:10772–10780). In this study, we examined the expression and function of α4β1 and VCAM‐1 in developing rat SCG and heart. In vitro, the α4β1‐dependent neurite outgrowth on VCAM‐1 decreased by approximately 50% from postnatal day 1 to 6. This down‐regulation was correlated with a shift in α4 isoform and a shift in α4 localization from neurites to cell bodies. This altered localization was also observed in vivo but on a different time scale. α4 was detected on most developing SCG neurons and on macrophages and blood vessels. In the heart, α4 was detected on sympathetic axons, but the percentage of α4‐positive fibers decreased with age. VCAM‐1 immunoreactivity was abundant in heart tissue throughout development, in close proximity to sympathetic axons. The regulation of α4β1 function, and localization of α4 and VCAM‐1, are consistent with a role for the α4β1–VCAM‐1 interaction in extension of sympathetic axons into the myocardium. Developmental Dynamics 231:359–369, 2004. © 2004 Wiley‐Liss, Inc.
Stat3 signaling is present and active during development of the central nervous system and eye of vertebrates
Authors: Yan Ye , Bian Wei , Xie Zhiqin , Cao Xinmin , Le Roux Isabelle , Guillemot Francois , Jing Naihe 
Published: July 2004

AbstractStat3, a member of the signal transducer and activator of transcription (STAT) family, plays a central role in mediating cell growth, differentiation, and survival signals. In this report, we show that Stat3 immunoreactivity was localized to specific regions in the developing mouse brain, neural tube, and eye from embryonic day 10.5 to postnatal day 0. The active form of Stat3 protein, which is phosphorylated on tyrosine 705 (pYStat3), was also found in the developing neural tube with more restricted distribution. An in ovo chick embryo electroporation assay showed that the endogenous chick Stat3 could drive consensus sis‐inducible element‐directed reporter gene expression. These results demonstrate that the active Stat3 protein is present and might play a role during the development of the central nervous system and eye. Developmental Dynamics 231:248–257, 2004. © 2004 Wiley‐Liss, Inc.
Role of cranial neural crest cells in visceral arch muscle positioning and morphogenesis in the Mexican axolotl, Ambystoma mexicanum
Authors: Ericsson Rolf , Cerny Robert , Falck Pierre , Olsson Lennart 
Published: July 2004

AbstractThe role of cranial neural crest cells in the formation of visceral arch musculature was investigated in the Mexican axolotl, Ambystoma mexicanum. DiI (1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine, perchlorate) labeling and green fluorescent protein (GFP) mRNA injections combined with unilateral transplantations of neural folds showed that neural crest cells contribute to the connective tissues but not the myofibers of developing visceral arch muscles in the mandibular, hyoid, and branchial arches. Extirpations of individual cranial neural crest streams demonstrated that neural crest cells are necessary for correct morphogenesis of visceral arch muscles. These do, however, initially develop in their proper positions also in the absence of cranial neural crest. Visceral arch muscles forming in the absence of neural crest cells start to differentiate at their origins but fail to extend toward their insertions and may have a frayed appearance. Our data indicate that visceral arch muscle positioning is controlled by factors that do not have a neural crest origin. We suggest that the cranial neural crest‐derived connective tissues provide directional guidance important for the proper extension of the cranial muscles and the subsequent attachment to the insertion on the correct cartilage. In a comparative context, our data from the Mexican axolotl support the view that the cranial neural crest plays a fundamental role in the development of not only the skeleton of the vertebrate head but also in the morphogenesis of the cranial muscles and that this might be a primitive feature of cranial development in vertebrates. Developmental Dynamics 231:237–247, 2004 © 2004 Wiley‐Liss, Inc.
Pluripotent neural crest stem cells in the adult hair follicle
Authors: Sieber‐Blum M. , Grim M. , Hu Y.F. , Szeder V. 
Published: July 2004

AbstractWe report the presence of pluripotent neural crest stem cells in the adult mammalian hair follicle. Numerous neural crest cells reside in the outer root sheath from the bulge to the matrix at the base of the follicle. Bulge explants from adult mouse whisker follicles yield migratory neural crest cells, which in clonal culture form colonies consisting of over a thousand cells. Clones contain neurons, smooth muscle cells, rare Schwann cells and melanocytes, demonstrating pluripotency of the clone‐forming cell. Targeted differentiation into Schwann cells and chondrocytes was achieved with neuregulin‐1 and bone morphogenetic protein‐2, respectively. Serial cloning in vitro demonstrated self‐renewal capability. Together, the data show that the adult mouse whisker follicle contains pluripotent neural crest stem cells, termed epidermal neural crest cells (eNCSC). eNCSC are promising candidates for diverse cell therapy paradigms because of their high degree of inherent plasticity and due to their easy accessibility in the skin. Developmental Dynamics 231:258–269, 2004. © 2004 Wiley‐Liss, Inc.
Innervation‐dependent and fiber type‐specific transcriptional regulation of the slow myosin heavy chain 2 promoter in avian skeletal muscle fibers
Authors: Jiang Hongbin , Jordan Theresa , Li Jinyuan , Li Hui , DiMario Joseph X. 
Published: July 2004

AbstractSkeletal muscle fiber type is regulated, in part, by innervation leading to transcriptional regulation of fiber type‐specific genes. Here, we report the initial characterization of the transcriptional regulation of the slow myosin heavy chain 2 (MyHC2) promoter in innervated and noninnervated slow medial adductor (MA) and fast pectoralis major (PM) muscle fibers in cell culture. The proximal 1358 bp of slow MyHC2 upstream DNA contains a functional E‐box and binding sites for myocyte enhancer factor 2 (MEF2) and nuclear factor of activated T cells (NFAT). Mutagenesis studies indicated that both MEF2 and NFAT binding sites are required for innervation‐induced slow MyHC2 promoter activity in MA muscle fibers. However, MEF2 transcription factor activity was unaffected by innervation and did not demonstrate fiber type‐specific interactions with the slow MyHC2 MEF2 binding site. NFAT transcription factor activity did increase in innervated MA muscle fibers and not in PM muscle fibers, indicating innervation and muscle fiber type‐specific regulation. However, transfection of constitutively active NFAT indicated that NFAT is insufficient to induce slow MyHC2 gene expression in either fast PM or slow MA muscle fibers without innervation. These results indicate the requirement for MEF2 and NFAT in innervation‐induced slow MyHC2 gene expression and suggest that additional innervation‐dependent and fiber type‐specific control of slow MyHC2 gene expression resides in MA and PM muscle fibers, respectively. Developmental Dynamics 231:292–302, 2004. © 2004 Wiley‐Liss, Inc.