bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of n‐butyl phenyl ether by tri‐liquid‐phase catalysis using poly(ethylene glycol)‐600 as a catalyst – analysis of factors affecting the reaction in a batch reactor
Authors: Hsiao Hsu‐Chin , Weng Hung‐Shan 
Published: August 2002

AbstractAs the second part of a series of studies on the synthesis of n‐butyl phenyl ether (ROPh) by tri‐liquid‐phase catalysis, this work examines the factors affecting the reaction between n‐butyl bromide (RBr, organic substrate) and sodium phenolate (NaOPh, aqueous nucleophile) with poly(ethylene glycol)‐600 (PEG‐600) as a phase‐transfer catalyst. The reaction is performed in a batch reactor at 45–85 °C for 2 h while the agitation speed is fixed at 1000 rpm. Experimental results indicate that the individual mole fractions of NaOPh and PEG‐600 slightly affect the reaction, while the total amount of these components exerts significant influence. When the mole fraction of PEG‐600 is 0.5, the reaction rate and the conversion of RBr are the highest. No byproducts are formed in the course of the reaction. The system using a non‐polar organic solvent might obtain a higher conversion compared with a weakly polar one owing to a higher concentration of PEG‐600 in the third liquid phase. Furthermore, adding NaOH facilitates the reaction to obtain a higher reaction rate than adding other kinds of salt because the addition of a base results in the formation of a third liquid phase. The catalytic ability of PEG with average molecular weight of 600 gmol−1 is far higher than that with average molecular weight of 200, 400 and 1000 because PEG‐600 possesses an appropriate chain length which can tightly associate with Na+ to form the complex of PEG‐600‐Na+OPh− for reacting with RBr. In addition, this nucleophilic substitution reaction is found to be pseudo‐first‐order with respect to RBr.© 2001 Society of Chemical Industry
Characterisation of flexible baffles in an oscillatory baffled column
Authors: Fitch A W , Ni X , Stewart J 
Published: August 2002

AbstractIn our previous studies the volume‐averaged strain rates, of 2–22 s−1, were obtained in an oscillatory baffled column (OBC) based on velocity measurements over a half baffled cell for oscillatory Reynolds numbers of 1000–4030. These values are very low compared with those in a traditional stirred tank vessel (at least >100 s−1) for similar operational conditions and the same power consumption. It was also observed that the volume‐averaged strain rates in the OBC fluctuated with the phase of oscillation over any cycle, with high values coinciding with eddy generation, and low values with eddy cessation. The objective of this study is to show that such fluctuations can be attenuated by employing innovative flexible baffles, whose inside edges move with the fluid oscillation. In this paper experimental measurements of velocity vector maps and strain rate distributions using Digital Particle Image Velocimetry (DPIV) are presented for both conventional and flexible baffles in an OBC. Mixing characterisation, in terms of axial dispersion coefficients, are compared for both baffle designs. The results show that the flexible baffles can reduce the fluctuations and magnitudes of the volume‐averaged strain rates in the OBC without compromising the mixing performance. Low and uniform strain rate distributions in time and space are essential biochemical, biomedical and pharmaceutical applications where shear sensitive cultures are involved.© 2001 Society of Chemical Industry
Solubilization of methanol and ethanol in palm oil stabilized by medium‐ and long‐chain alkanols
Authors: Dzulkefly K , Lim W H , Hamdan S , Norsilah K 
Published: August 2002

AbstractSolubilization of methanol and ethanol in crude palm oil, refined, bleached and deodorized palm oil (RBD PO) and RBD palm olein (POL) was studied using medium‐ and long‐chain alkanols (C4–C12). Ternary phase diagrams were constructed to determine the solubilization (isotropic) region. The results showed that methanol and ethanol are solubilized to a greater extent in an unsaturated palm olein than the saturated CPO and RBD PO in the presence of long‐chain alkanols. The minima of the solubilization curves for dodecanol, decanol and octanol were 27%, 30% and 33% of alkanol respectively in the methanol system, whereas in the ethanol system, the minima for the same alkanols were found at 22%, 24% and 27%. The longer chain‐length alkanol (dodecanol) requires a lesser amount (21% and 32%) to achieve miscibility compared with 53% and 57% for butanol in mixtures containing 70:30 and 50:50 wt ratios respectively. The kinematic viscosity of the isotropic solutions increases with the chain‐length and percentage of alkanols. Solubilization using a POL/methanol/butanol system significantly reduced the kinematic viscosity of POL from 72.7 mm2 s−1 to the value allowable for No 2 diesel fuel (1.9–4.1 mm2 s−1) or about a 96% reduction from the initial kinematic viscosity of POL.© 2002 Society of Chemical Industry
Fragile X syndrome, the Fragile X related proteins, and animal models
Authors: Hoogeveen André T. , Willemsen Rob , Oostra Ben A. 
Published: August 2002

AbstractThe Fragile X syndrome (FraX), which is characterized among other physical and neurologic impairments by mental retardation, is caused by the absence of the product of the FMR1 gene. The Fragile X Mental Retardation Protein (FMRP) is a member of a novel family of RNA‐binding proteins. The latter includes two other proteins highly homologous with FMRP: the fragile X related proteins 1 and 2 (FXRP1 and FXRP2). Characterization of FXRPs, including their interaction with FMRP, will provide critical information about the mechanisms of action of FMRP and the role of this group of proteins in FMRP‐deficient conditions such as FraX. Genetic manipulations of FMRP and the FXRPs should also provide valuable tools for investigating pathophysiology and gene therapies in FraX. The present review summarizes the strategies used for identifying the FXRPs, their chromosomal localization, molecular structure, and tissue distribution. It also reviews interactions between different members of this family of RNA‐binding proteins. Animal models, both knockout and transgenic, of FMRP and the FXRPs are discussed. Phenotypic features of the FMR1 knockout mouse, the FMR1 transgenic rescue mouse, and other novel strategies for manipulating and delivering FMRP and FXRPs to the brain and other tissues are described. Microsc. Res. Tech. 57:148–155, 2002. © 2002 Wiley‐Liss, Inc.
Regulation of adhesive interaction between podocytes and glomerular basement membrane
Authors: Kretzler Matthias 
Published: August 2002

AbstractGlomerular filtration depends on well‐orchestrated cell–cell and cell–matrix contacts of glomerular podocytes. Over the last years critical constituents of these contacts have been identified via molecular approaches. Podocyte cell–matrix interactions have been shown to be mediated in part by α3β1‐integrin heterodimers. Disturbances of integrin matrix interaction lead to detachment of podocytes in vitro, corresponding to the critical event of foot process retraction and glomerular basement membrane (GBM) denudation in vivo. Further, dystroglycan‐mediated matrix attachment appears to play a critical role for podocyte foot process architecture. Downstream signaling events are currently elucidated concentrating mainly on integrin‐dependent cascades and their consequences for podocyte adhesion and proliferation. An activation of the integrin‐linked kinase in podocyte damage in vivo and in vitro makes this molecule a particularly interesting candidate for integrin‐mediated inside‐out and outside‐in signaling in podocytes. Podocyte cell–cell interaction has been characterized in a few studies in vitro, indicating the slit diaphragm to be a modified adherens junction. The structural link between the cell–matrix and cell–cell contacts is maintained by the actin cytoskeleton, which may also enable cross‐talk between these two cell contact sites. Examining podocyte function in tissue culture, animal models and human expression studies should allow further detailed dissection of the molecular pathways responsible for maintenance and failure of the glomerular filtration barrier. Microsc. Res. Tech. 57:247–253, 2002. © 2002 Wiley‐Liss, Inc.
Diabetic vascular dysfunction: Links to glucose‐induced reductive stress and VEGF
Authors: Tilton Ronald G. 
Published: August 2002

AbstractA complete biochemical understanding of the mechanisms by which hyperglycemia causes vascular functional and structural changes associated with the diabetic milieu still eludes us. In recent years, the numerous biochemical and metabolic pathways postulated to have a causal role in the pathogenesis of diabetic vascular disease have been distilled into several unifying hypotheses. These involve either increased reductive or oxidative stress to the cell, or the activation of numerous protein kinase pathways, particularly protein kinase C and mitogen‐activated protein kinases. As detailed below, there is tremendous crosstalk between these competing hypotheses. We propose that increased tissue glucose levels alter cytosolic coenzyme balance by increased flux of glucose through the sorbitol pathway increasing free cytosolic NADH levels. Increased NADH levels can generate reactive oxygen species via numerous mechanisms, lead to the formation of intracellular advanced glycation end products, and induce growth factor expression via mechanisms involving protein kinase C activation. The elevation in growth factors, particularly vascular endothelial growth factor (VEGF), is responsible for the vascular dysfunction via numerous mechanisms reported here in detail. Microsc. Res. Tech. 57:390–407, 2002. © 2002 Wiley‐Liss, Inc.
Differential response of mature TrkA/p75NTR expressing human and pig oligodendrocytes: Aging, does it matter?
Authors: Althaus Hans H. , Mursch Kay , Klöppner Sabine 
Published: August 2002

AbstractA differential morphological response of mature oligodendrocytes (OL) isolated from human and pig brains to the phorbol ester 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) and to the nerve growth factor (NGF) was observed. In both cases, OL regenerate their processes; however, the rate and the extension of the process formation of human OL were behind that of pig OL. Presumably, the advanced age of the human tissue in these experiments might have contributed to this decrease in process formation, an effect that was already observed for rat OL [Yong et al. (1991) J Neurosci Res 29:87–99]. The less effectivity of NGF via TrkA, which was immunocytochemically shown in human OL, and of TPA via the protein kinase C (PKC) pathway, may have its common focus on the mitogen‐activated protein kinase (MAPK) cascade. In this context, it was noted that only a few studies on aging of mature OL are available. It is conceivable that age‐related changes in the properties of OL could be an important factor for their cellular responsiveness during longer lasting demyelinating diseases such as multiple sclerosis. Hence, this review would like to provide a basis for future investigations on the aging of mature OL. The data presently available suggest a preliminary classification of mature OL into three categories. Microsc. Res. Tech. 52:689–699, 2001. © 2001 Wiley‐Liss, Inc.
Alveolar macrophage–T cell interactions during Th1‐type sarcoid inflammation
Authors: Agostini Carlo , Facco Monica , Chilosi Marco , Semenzato Gianpietro 
Published: August 2002

AbstractSarcoidosis is an immunomediated, multisystem disorder of unknown cause(s) characterized by a heightened Th1 immune response that leads to an uncontrolled granuloma formation at sites of disease activity. The past few years have seen outstanding advances in the understanding of immunological and molecular events involved in the pathogenesis of this disease. The idea is that several cytokines and chemokines, which are secreted at sites of disease activity, participate in granuloma formation. This paper describes recent data that have clarified some of the events that govern the development of the hypersensitivity reaction during sarcoidosis. In particular, we will review recent evidence indicating that a complex relationship exists between the macrophage/lymphocyte cellular axis and the tissue networks of cytokines. Microsc. Res. Tech. 53:278–287, 2001. © 2001 Wiley‐Liss, Inc.
Expression of SR‐BI (Scavenger Receptor Class B Type I) in turtle (Chrysemys picta) tissues and other nonmammalian vertebrates
Authors: Duggan Annemarie E. , Marie Ronald Ste. , Callard Ian P. 
Published: August 2002

AbstractIn this study, the tissue distribution of the expression of an HDL‐receptor (SR‐BI; Scavenger Receptor Class B Type I) was investigated in the turtle using an antiserum to murine SR‐BI. Several turtle tissues including liver, heart, small intestine, kidney, oviduct, ovary, and testis were shown to express an 82 kDa membrane protein. In addition, SR‐BI expression in livers of other nonmammalian species such as the chicken, frog, goldfish, shark, and skate is also reported. Ovarian SR‐BI expression varies seasonally in the turtle as do plasma levels of apoA‐I and cholesterol ester. It is possible that changing levels of SR‐BI, the receptor for apoA‐I, is physiologically relevant to the demands of the turtle ovarian cycle and cholesterol distribution. J. Exp. Zool. 292:430–434, 2002. © 2002 Wiley‐Liss, Inc.
High performance liquid chromatographic separation of steroids from ovarian follicles of fresh water perch Anabas testudineus: Identification and characterization of the maturation‐inducing hormone
Authors: Bhattacharyya Sanghamitra , Sen Utpal , Bhattacharyya Sachi Prasad , Mukherjee Dilip 
Published: August 2002

AbstractAccurate separation and identification of steroids from the postvitellogenic ovarian follicles of Indian climbing perch Anabas testudineus was performed by high‐performance liquid chromatography (HPLC) and specific radioimmunoassay (RIA). The steroids from such follicles, incubated in Cortland’s saline with or without homologous fish pituitary extract (FPE), were extracted with dichloromethane and separated on a μBondapak C18 column. Identification of the HPLC fractions was further confirmed by thin layer chromatography. As HPLC peaks for 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) and testosterone (T) were close, clear separation of these steroids and accurate measurement of their quantities was achieved by RIA of HPLC fractions using specific antibodies. Altogether, nine eluted fractions in the FPE‐untreated and ten in FPE‐treated samples were obtained. Of these, six were identified as: 5β‐pregnan‐3α,17α,20β‐triol (5β‐3α,17α,20β‐P); DHP; T; 17α‐hydroxyprogesterone (17α‐P4); progesterone (P4); and androstenedione (AD). Three fractions from untreated and four from FPE‐treated samples, however, remained unidentified. Of all the HPLC fractions examined for their relative maturational inducing (MI) potency on full grown (postvitellogenic) ovarian follicles of perch, the fraction identified as DHP was found to be the most effective inducer of germinal vesicle breakdown (GVBD) both at low and high concentrations. Fractions identified as 5β‐3α,17α,20β‐P and 17α‐P4 could induce only 32% and 20% GVBD at their highest concentration, while none of the unidentified fractions showed any MI activity. FPE caused increased production of DHP, testosterone, and 5β‐3α,17α,20β‐P. The qualitative differences between the fractions obtained from FPE‐treated samples and those from FPE‐untreated samples were only the appearance of a new polar metabolite of unknown function. The present study showed that, as a single steroid, DHP was the most potent MIH for A. testudineus. J. Exp. Zool. 292:565–572, 2002. © 2002 Wiley‐Liss, Inc.
Sex determination in the chicken embryo
Authors: Smith Craig A. , Sinclair Andrew H. 
Published: August 2002

AbstractThe chicken embryo represents a suitable model for studying vertebrate sex determination and gonadal sex differentiation. While the basic mechanism of sex determination in birds is still unknown, gonadal morphogenesis is very similar to that in mammals, and most of the genes implicated in mammalian sex determination have avian homologues. However, in the chicken embryo, these genes show some interesting differences in structure or expression patterns to their mammalian counterparts, broadening our understanding of their functions. The novel candidate testis‐determining gene in mammals, DMRT1, is also present in the chicken, and is expressed specifically in the embryonic gonads. In chicken embryos, DMRT1 is more highly expressed in the gonads and Müllerian ducts of male embryos than in those of females. Meanwhile, expression of the orphan nuclear receptor, Steroidogenic Factor 1 (SF1) is up‐regulated during ovarian differentiation in the chicken embryo. This contrasts with the expression pattern of SF1 in mouse embryos, in which expression is down‐regulated during female differentiation. Another orphan receptor initially implicated in mammalian sex determination, DAX1, is poorly conserved in the chicken. A chicken DAX1 homologue isolated from a urogenital ridge library lacked the unusual DNA‐binding motif seen in mammals. Chicken DAX1 is autosomal, and is expressed in the embryonic gonads, showing somewhat higher expression in female compared to male gonads, as in mammals. However, expression is not down‐regulated at the onset of testicular differentiation in chicken embryos, as occurs in mice. These comparative data shed light on vertebrate sex determination in general. J. Exp. Zool. 290:691–699, 2001. © 2001 Wiley‐Liss, Inc.
Fractional chromatic numbers of cones over graphs
Authors: Tardif Claude 
Published: August 2002

AbstractWe introduce a construction called the cone over a graph. It is a natural generalisation of Mycielski's construction. We give a formula for the fractional chromatic numbers of all cones over graphs, which generalizes that given in 3 for Mycielski's construction. © 2001 John Wiley & Sons, Inc. J Graph Theory 38: 87–94, 2001
Effect of the rate of gadolinium injection on magnetic resonance pulmonary perfusion imaging
Authors: Matsuoka Shin , Uchiyama Katsuhiro , Shima Hideki , Terakoshi Hiroaki , Oishi Sonomi , Nojiri Yoko , Ogata Hitoshi 
Published: August 2002

AbstractPurposeTo determine whether the injection rate of contrast agent affects the dynamics of enhancement of the pulmonary parenchyma on magnetic resonance (MR) pulmonary perfusion imaging.Materials and MethodsFifteen healthy volunteers underwent enhanced MR pulmonary perfusion imaging to evaluate the effects of different injection rates. Injection rates were 1, 3, or 5 mL/second. Regions of interest (ROIs) were chosen in the lung and aorta to analyze the change in signal intensity over time.ResultsAs the injection rate increased, the peak enhancement occurred significantly earlier (P = 0.0012), but the peak enhancement signal‐to‐noise ratio (SNR) value was not affected (P = 0.25). With the 3‐ and 5‐mL/second injection rates, images of both the pulmonary circulation and systemic circulation were obtained separately. However, with 1 mL/second, higher enhancement of the aorta was overlapped with peak enhancement of the lung tissue.ConclusionThe injection rate affects the enhancement profiles of the pulmonary parenchyma. J. Magn. Reson. Imaging 2002;15:108–113. © 2002 Wiley‐Liss, Inc.
MR‐guided percutaneous core biopsy of small breast lesions: First experience with a vertically open 0.5T scanner
Authors: Schneider Jens P. , Schulz Thomas , Horn Lars C. , Leinung Steffen , Schmidt Frank , Kahn Thomas 
Published: August 2002

AbstractPurposeThe growing use of highly sensitive but only moderate specific breast MRI requires the development of both minimal‐invasive as well as precise biopsy systems. The aim of the study was to prove the accuracy and feasibility of a biopsy procedure carried out in prone position in a vertically opened MR imager.Materials and MethodsThe biopsies were carried out in 21 women with lesions visible on MRI alone using an open breast coil with an integrated biopsy device. A 14 G coaxial needle was placed under near real‐time MRI‐guidance. After the tip of this needle was verified in contact with the lesion, we used a non MR‐compatible, but MR‐safe biopsy gun with a 16 G canula to take four to eight cores.ResultsWe found eight malignant and 12 benign lesions. In one patient the procedure was not successful. In case of malignancy, the operation confirmed the diagnosis in all cases. The 12/21 patients with benign lesions have been followed without evidence of lesions growth over eight to 28 months.ConclusionThe described procedure allows MRI‐guided minimal invasive core biopsy of small breast lesions (five to 17 mm) with a high degree of accuracy. J. Magn. Reson. Imaging 2002;15:374‐385. © 2002 Wiley‐Liss, Inc.
MRI in France: The French paradox
Authors: Lavayssière Robert , Cabée Anne‐Elizabeth 
Published: August 2002

AbstractAlthough France is a modern, developed country, which spends nearly 10% of the gross national product on healthcare and has a highly praised level of medicine, the number of modern imaging scanners, such as CT (595), MRI (182), and PET (5), is quite low when compared to other European countries. Politics and a long‐standing tradition of centralization are prominent among reasons for such an underdevelopment. This situation has resulted in another French paradox not linked to wine consumption. The French life expectancy is very high, but the number of imaging equipment is very low. J. Magn. Reson. Imaging 2001;13:528–533. © 2001 Wiley‐Liss, Inc.
Development of clinical MR imaging in Russia and other CIS countries
Authors: Sinitsyn Valentin E. 
Published: August 2002

AbstractThis paper summarizes the development of magnetic resonance imaging (MRI) in the health systems of the USSR and later in Russia and the neighboring countries. Nuclear magnetic resonance (NMR) has been used as a scientific tool in the USSR since the 1940s. In 1982 the first whole‐body MR imager was installed. By the end of 1999, 131 MR systems were operating in Russia. There are substantial regional differences in the number of units installed. Russia has a domestic production of low‐field MR units. There are also plans for domestic production of MR contrast agents. Other former USSR republics have much less MR equipment. Most of the MRI centers experience difficulties in maintaining equipment in working condition. Some positive changes in the national health service systems give reason to believe in an increase in the quantity of MR units and the quality of their clinical use. J. Magn. Reson. Imaging 2001;13:645–647. © 2001 Wiley‐Liss, Inc.
Fast spin echo and fast gradient echo MRI with low acoustic noise
Authors: Hennel Franciszek 
Published: August 2002

AbstractIt has been shown previously that a significant reduction of the acoustic noise in standard, slow magnetic resonance imaging (MRI) sequences is achieved when the gradient pulses have long sinusoidal ramps. An improvement of this method is now presented for fast gradient echo (FLASH) and fast spin echo (RARE) sequences. The new strategy consists of using a sinusoidal readout pulse with no plateau and extending the phase encoding pulses to the entire readout period. The distribution of k‐space samples is no longer equidistant, and images have to be reconstructed with gridding. A reduction of the acoustic noise by 20–40 dBA was obtained with respect to standard sequences installed by the scanner manufacturer, which is 10–20 dBA better than that with the previously proposed method of sinusoidal ramps. J. Magn. Reson. Imaging 2001;13:960–966. © 2001 Wiley‐Liss, Inc.