bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on fibers spun from poly(vinyl alcohol‐b‐acrylonitrile) emulsions prepared by ultrasonic technique. I. Characterization of fiber structure
Authors: Xiao L. , Xiao W. , Liu Q. , Chen K. , Xu X.
Published: August 2002

The structural characteristics of poly(vinyl alcohol‐b‐acrylonitrile) fibers with different AN contents were studied by comparison with that of PVA and PAN fibers. X‐ray diffraction analysis showed that both PVA and PAN blocks in the copolymer fibers formed crystals. Two glass transition temperatures corresponding to PVA and PAN components appeared on the dynamic mechanical spectrum of the copolymer fiber, indicative of their incompatibility in the fiber. SEM intuitively exhibited a longitudinal cracked and grooved surface morphology similar to that of PAN fiber and revealed an internal microdomain separation morphology for the block copolymer fibers. TEM showed a morphological structure intermediate between those of PVA and PAN fibers for the block copolymer fibers. It was also found that the copolymer fiber with the lower AN content has a sheath–core structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 979–988, 2001
Synthesis and properties of alkyl‐substituted poly(1,4‐phenylenevinylene) derivatives
Authors: Zheng Junrong , He Gufeng , Yang Chunhe , Huang Lan , Li Yongfang
Published: August 2002

The luminescent poly(2‐dodecyl‐5‐methyl‐1,4‐phenylenevinylene) was synthesized with a new synthetic route. The structure and properties of the polymers were characterized by IR, UV‐vis, luminescent spectra, GPC, and both thermal and elemental analysis. The glass‐transition temperature increases and the photoluminescent relative quantum yield decreases with the increase of the conjugation extent of the polymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1299–1304, 2001
Cellulose–poly(acrylamide–acrylic acid) interpenetrating polymer network membranes for the pervaporation of water–ethanol mixtures. II. Effect of ionic group contents and cellulose matrix modification
Authors: Buyanov A. L. , Revel'Skaya L. G. , Kuznetzov Yu. P. , Khripunov A. K.
Published: August 2002

The separation properties in the dehydration of a water–ethanol mixture and the swelling behavior of interpenetrating polymer network (IPN) pervaporation membranes based on a cellulose or cellulose–hydroxyethyl cellulose (HEC) matrix and poly(acrylamide and/or acrylic acid) were investigated depending on the ionic acrylate groups content (γ) in synthetic polymer chains (0–100 mol %), the HEC content in the matrix (0–50 wt %), and the temperature (25–60°C). The separation factor (α), permeation rate (P), and separation index (αP) significantly improved with increasing γ values only for the separation of concentrated ethanol solutions (∼86 wt %). For more dilute solutions of ethanol (∼46 wt %), the P and αP values also increased but no considerable increase in α was observed. All types of membranes based on the cellulose matrix were characterized by a drastic decrease in the values of P at [EtOH] ≥90 wt % and, as a result, a decrease in the separation index (kg m−2 h−1) from ∼2000 (for 86 wt % EtOH, 50°C) to ∼240 (for 95 wt % EtOH, 50°C), which correlates with a decrease in the degree of membrane swelling. The modification of the cellulose matrix by introducing HEC into it makes it possible to increase considerably the membrane swelling in concentrated EtOH solutions and, hence, the αP value to ∼760 (95 wt % EtOH, 50°C). All types of IPN membranes exhibit a marked increase in both α and P when the temperature increases from 25 to 60°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1452–1460, 2001
Phenolic resins with phenyl maleimide functions: Thermal characteristics and laminate composite properties
Authors: Bindu R. L. , Nair C. P. Reghunadhan , Ninan K. N.
Published: August 2002

Phenolic resins bearing varying concentrations of phenyl maleimide functions were synthesized by copolymerizing phenol with N‐(4‐hydroxyphenyl)maleimide (HPM) and formaldehyde in the presence of an acid catalyst. The resins underwent a two‐stage curing, through condensation of methylol groups and addition polymerization of maleimide groups. The cure characterization of the resin by dynamic mechanical analysis confirmed the two‐stage cure and the dominance of maleimide polymerization over methylol condensation in the network buildup process. The kinetics of both cure reactions, studied by the Rogers method, substantiated the earlier proposed cure mechanism for each stage. Although the initial decomposition temperature of the cured resin was not significantly improved, enhancing the crosslink density through HPM improved thermal stability of the material in a higher temperature regime. The anaerobic char yield also increased proportional to the maleimide content. Isothermal pyrolysis and analysis of the char confirmed that pyrolysis occurs by loss of hydrocarbon and nitrogenous products. The resins serve as effective matrices in silica‐ and glass fabric–reinforced composites whose mechanical properties are optimum for moderately crosslinked resins, in which failure occurs through a combination of fiber debonding and resin fracture. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1664–1674, 2001
Film formation of monodispersed polystyrene latex at high temperature
Authors: Yang Zhen‐Zhong , Wang Li‐Jun , Liu Zheng‐Ping , Zhao De‐Lu
Published: August 2002

This report discusses the drying behavior of monodispersed polystyrene latex at elevating temperature with particular attention to the relationship between water evaporation rate and morphological evolution during the film formation process. At the first stage, water evaporation rate was less influenced by the skin film formed at the latex/air interface, which was consistent with Croll's model. During this stage, a drying front advanced from the top film toward the bulk dispersion. At the final stage of film formation, the water evaporation rate was less than that of the initial stage, and another drying front developed from the interior region outside the system. Two distinct boundaries corresponding to the opposite directions of the second drying front between completely dried region and wet region were found if the film was peeled off the container surface. Besides, some particular morphologies were found in the completely dried region, which was likely related to preferable coalescence among the particles induced by capillary force because of water evaporation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1835–1840, 2001
Decreasing pollution of plasticized PVC packaging: A comparison of three plastic treatments
Authors: Fugit Jean‐Luc , Taverdet Jean‐Louis
Published: August 2002

This study proposed three different treatments of plasticized PVC, which decreases diffusion of the plasticizer when the plastic is in contact with a liquid food or simulated liquid food. The treated PVCs were tested under the same operating conditions, and their efficiency was able to be assessed thanks to a diffusion model previously described. It was shown that the time and the temperature of the storage of the treated PVCs influenced the effectiveness of the treatment. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1841–1847, 2001
Novel regenerable N‐halamine polymeric biocides. II. Grafting hydantoin‐containing monomers onto cotton cellulose
Authors: Sun Yuyu , Sun Gang
Published: August 2002

A novel cyclic‐amine monomer, 3‐allyl‐5,5‐dimethylhydantoin (ADMH) was synthesized with good yield by the reaction of allyl bromide with 5,5‐dimethylhydantoin (DMH), and was characterized by FTIR and 1H‐NMR spectra. ADMH alone cannot be grafted onto other polymers. However, the presence of acrylonitrile markedly enhanced the ADMH graft yield onto cotton cellulose. The influence of reaction conditions on the graft copolymerization was investigated. After chlorine bleach treatment, hydantoin units in the grafted copolymers were easily transformed into N‐halamine structures. Grafted samples exhibited potent antibacterial activity against Escherichia coli, and the functional properties were shown to be durable and regenerable. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 617–624, 2001
Controlled release of carboxylic‐containing herbicides by starch‐g‐poly(butyl acrylate)
Authors: Zhu Zhifeng , Zhuo Renxi
Published: August 2002

The use of starch‐g‐poly(butyl acrylate) as a new material for encapsulating carboxylic‐containing herbicides such as 2,4‐dichlorophenoxyacetic acid and 2,4,5‐trichlorophenoxyacetic acid for controlled release was studied. The herbicides were individually encapsulated within the modified starch substrate, which was graft‐copolymerized with a small amount of butyl acrylate. The modification of starch induced a hydrophobic behavior in the matrix, made it swell less, and caused the release rate to slow, especially for herbicides with higher water solubility. Therefore, the survival life of the starch products for controlled release could be expected to extend to some extent compared with that of natural starch. In addition, the effects of the molecular weight, herbicide content, and particle size on the swellability and release behavior were also investigated. Scanning electron microscopy revealed that the herbicides encapsulated within the starch matrix were dispersed in the form of tiny cell. Consequently, the herbicides encapsulated were released through diffusion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1535–1543, 2001
Preparation of chlorosulfonated polyethylene by the gas‐solid method
Authors: Zhao Ruofei , Cheng Shujun , Shun Yan , Huang Yongjun
Published: August 2002

Chlorosulfonated polyethylene (CSM) has been prepared by the gas‐solid method in a tank reactor using chlorinated polyethylene (CPE) and a gaseous mixture of chlorine and dioxide sulfur. Sulfur content of CSM determined by element analysis is used as a reference for the quantitative determination of the degree of chlorosulfonation. The effects of reaction temperature, effective gaseous mixture concentration, particle size of CPE, and the ratio of chlorine to dioxide sulfur on chlorosulfonation are investigated. The results indicate that with the increment of reaction temperature within the range of from 30 to 50°C, the rate of chlorosulfonation during the later reaction period (15–25 min) is markedly increased and the prepared CSM has higher sulfur content. It was also found that the rate of chlorosulfonation increases with the effective gaseous mixture concentration, and that the ratio of chlorine to dioxide sulfur is preferably 1 : 1. It was proven that HCl, by‐product of the chlorosulfonation, can accelerate the rate of chlorosulfonation when the volume concentration of HCl is lower than 40%, and that the presence of oxide results in higher sulfur content of the resultant CSM. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3582–3588, 2001
Effect of the agitation rate on the generation of low‐crystallinity cellulose from phosphoric acid
Authors: Kumar Vijay , Kothari Sanjeev , Banker G. S.
Published: August 2002

Changes in the basic powder properties of low‐crystallinity powder cellulose (LCPC) as a function of the agitation rate used during its generation from phosphoric acid were investigated. We reacted cotton linter with phosphoric acid (85% w/v) at room temperature for an hour and then at 50°C for 3 h to produce the LCPC solution. The latter was slowly added to water (ca. 10 times the volume of phosphoric acid used) at a constant agitation rate of 700, 2000, or 4000 rpm. LCPC powder thus formed was collected by filtration, washed with water and acetone, and dried at 30°C. Scanning electron micrographs showed the three products to be highly aggregated in structure. The crystallinities of LCPC prepared at 700, 2000, and 4000 rpm were 39, 31, and 24%, respectively. The crystalline component of LCPC produced at 700 and 2000 rpm contained both cellulose II (major component) and cellulose I (minor component), whereas LCPC generated at 4000 rpm belonged to the cellulose II crystal lattice. The porosity and true, bulk, and tap densities of LCPC made at 4000 rpm were 88.55% and 1.435, 0.138, and 0.164 g/cc, respectively. The corresponding values for LCPC made at 700 and 2000 rpm were 60.30% and 1.452, 0.541, and 0.576 g/cc and 54.49% and 1.465, 0.583, and 0.667 g/cc, respectively. Avicel® PH‐101, in contrast, had a degree of crystallinity of 89% and a true density value of 1.577 g/cc. The porosity, bulk density, and tap density values were intermediate to those of LCPC made at 4000 rpm and 700 or 2000 rpm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2624–2628, 2001
Synthesis of graft copolymers. II. Synthesis of polystyrene‐g‐poly(methyl methacrylate)
Authors: Morales Graciela , Guerrero Ramiro
Published: August 2002

The thermolysis of labile 1,2‐bis(trimethylsilyloxy)tetraphenylethane groups pendant along polystyrene chains in the presence of various vinyl monomers leads to the direct synthesis of graft copolymers. Depending on the monomer chosen, the polymerization temperature, and the number of active sites by the macroinitiator molecule, crosslinked or total soluble graft copolymers can be prepared. Several conditions were studied in order to attain soluble polystyrene‐g‐poly(methyl methacrylate) copolymers under a controlled polymerization mechanism. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 12–18, 2002
Physical properties of lyocell fibers spun from different solution‐dope phases
Authors: Kim Dong Bok , Lee Wha Seop , Jo Seong Mu , Lee Young Moo , Kim Byoung Chul
Published: August 2002

The hydration number (n) of NMMO hydrates has a significant effect on the rheological properties and phase of the cellulose solutions in the hydrates. The physical properties of the lyocell fibers spun from the cellulose solutions in NMMO hydrates with different values of n were investigated relative to the phase of the solution dope. NMMO hydrate with n = 1.1 could not fully dissolve cellulose, resulting in a heterogeneous solution. NMMO hydrate with n = 0.72 produced a mesophase solution that exhibited a good spinnability. When NMMO hydrates with n = 0.72 and 1.0 were used, the lyocell fiber spun from 15 wt % solution dope gave higher tensile strength than that spun from 12 wt % solution dope. NMMO hydrate with n = 1.0 produced a lyocell fiber whose tensile strength was slightly affected by spin–draw ratio but the tensile strength of the lyocell fiber prepared from NMMO hydrate with n = 0.72 was monotonically increased with increasing spin–draw ratio. Further, the latter gave higher birefringence. The lyocell fiber spun from 15 wt % solution in NMMO hydrate with n = 0.72 produced finely fibrillated structures. When treated with sonic wave the lyocell fiber prepared from 15 wt % cellulose (DPw 940) solution in NMMO hydrate with n = 0.72 yielded the most serious fibrillation on the fiber surface. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 981–989, 2002
Synthesis of a novel polymethacrylamide bearing cyclic perfluoroalkyl groups
Authors: Hayakawa Yoshio , Hayashi Eiji
Published: August 2002

A novel chiral methacrylamide bearing perfluoropyrrolidino groups was synthesized. Perfluoro(2‐pyrrolidinopropionyl fluoride), the starting material, was prepared by electrochemical fluorination and resolved into enantiomeric derivatives by preparative high performance liquid chromatography (HPLC) performed with optically active 1‐phenethylamine as the diastereomeric counterpart. The polymethacrylamide was obtained by radical polymerization. A clear, colorless, tough film of the polymer was formed by the solution‐casting technique, which showed excellent water repulsion with a contact angle of water greater than 100°. Column packings prepared by the coating of silica gels with the optically active polymer showed potential as the chiral stationary phase for HPLC resolving racemic 1,1′‐bi‐2‐naphthol (separation factor = 1.56) with a hexane–isopropanol mixture as the eluent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1443–1448, 2002
Expression of HNK1 epitope by the cardiomyocytes of the early embryonic chick: In situ and in vitro studies
Authors: Nakajima Yuji , Yoshimura Kazunori , Nomura Masahiko , Nakamura Hiroaki
Published: August 2002

Monoclonal antibody HNK1 reacts with a carbohydrate epitope in cell surface glycoproteins and glycolipids. During development, in various species the HNK1 epitopes are expressed in migrating neural crest cells and in the developing conduction cardiomyocytes. The conduction system is generally thought to be developed from cardiomyocytes, but some investigators have hypothesized that it is derived from the neural crest because conduction myocytes express neural antigens, including HNK1. Using immunohistochemistry, we examined the spatiotemporal expression of HNK1 in early chick cardiogenesis (stages 4 to 18) and whether cultured precardiac mesoderm does or does not express HNK1 as well as sarcomeric myosin (MF20). HNK1 was first expressed in the premyocardium at stage 8. At stage 10, HNK1‐positive cardiomyocytes were scattered along the straight heart tube. By stage 18, HNK1‐positive cardiomyocytes had become restricted to the atrium and sinus venosus. Atrioventricular cushion mesenchyme also expressed an HNK1 epitope. Immunostaining of HNK1 and MF20 in cultured precardiac mesoderm showed that there are at least three types of cells: 1) cardiomyocytes without HNK1 expression, 2) cells possessing both HNK1‐ and MF20‐immunoreactivity, and 3) mesenchymal cells with HNK1. Immunogold electron microscopy showed that cardiomyocytes containing sparsely distributed myofibrils associated with the Z‐band react with anti‐HNK1 antibody. Our observations showed a direct evidence for the first time that the precardiac mesoderm generates HNK1‐positive cardiomyocytes with morphological features similar to those of conduction cardiomyocytes. Anat Rec 263:326–333, 2001. © 2001 Wiley‐Liss, Inc.
Ranked retrieval with semantic networks and vector spaces
Authors: Kulyukin Vladimir A. , Settle Amber
Published: August 2002

The equivalence of semantic networks with spreading activation and vector spaces with dot product is investigated under ranked retrieval. Semantic networks are viewed as networks of concepts organized in terms of abstraction and packaging relations. It is shown that the two models can be effectively constructed from each other. A formal method is suggested to analyze the models in terms of their relative performance in the same universe of objects.
Financial analysis using Bayesian networks
Authors: Gemela Jozef
Published: August 2002

This paper illustrates opportunities of using probabilistic Bayesian networks in fundamental financial analysis. In it, we will present an application based on construction of a Bayesian network from a database of financial reports collected for the years 1993–1997. We will focus on one sector of the Czech economy — engineering — presenting examples that use the constructed Bayesian network in the sector financial analysis and financial analysis of individual enterprises. Copyright © 2001 John Wiley & Sons, Ltd.
Identification of κ and λ chains of the major immunoglobulin G subclasses by capillary zone electrophoresis
Authors: Katsougraki P. , Heliopoulos J. , Lamari F. , Militsopoulou M. , Anagnostides S. , Piperidou H. , Monos D. , Karamanos N. K.
Published: August 2002

Immunoglobulins are present in most tissues and plasma and play crucial role in immune system. Alteration of the levels of the immunoglobulin G (IgG) subclasses (IgG1, IgG2, IgG3 and IgG4) is an indication of a disturbed immunological response. The aim of the present study was the development of a capillary electrophoresis (CE) method for the analysis of IgG subclasses in respect to their variable κ and λ chains. Various analytical conditions and CE modes, including capillary zone electrophoresis (CZE), capillary isoelectric focusing (CIEF) and micellar electrokinetic capillary chromatography (MECC) have been thoroughly studied. CZE was found to be the most convenient way to separate IgG subclasses. Three of the human IgG subclasses were resolved using uncoated fused‐silica and 50 mM phosphate, pH = 9.3, as operating buffer at 20 kV and detection at 214 nm. IgG1κ was completely separated from IgG2κ and IgG3κ, whereas IgG2κ co‐migrated with IgG4κ, which is the minor IgG subclass. Under the same conditions IgG4λ was completely separated from IgG1λ, IgG2λ and IgG3λ, enabling the identification of the various λ chains. The developed CE method is rapid and can be applied to the identification of the major immunoglobulin G subclasses in respect to their variable κ and λ chains. Copyright © 2002 John Wiley & Sons, Ltd.
Challenges in Supporting Student Learning and Success Through Student Services
Authors: Williams Terry E.
Published: August 2002

Student service units in community colleges are challenged by the increasing diversity of the student population, the call for a renewed focus on student learning and success, and the need to demonstrate more clearly the value‐added dimensions of their work.
Heparin and coumadin versus acetylsalicylic acid for prevention of restenosis after coronary angioplasty
Authors: Garachemani Ali Reza , Fleisch Martin , Windecker Stephan , Pfiffner Dorothy , Meier Bernhard
Published: August 2002

The purpose of the present study was to determine whether postprocedural antithrombotic therapy with prolonged heparin infusion followed by 6 months of oral anticoagulation in addition to acetylsalicylic acid (ASA) reduces the incidence of angiographic restenosis after successful PTCA. One hundred ninety‐one patients with uncomplicated PTCA were randomized into two groups: one group was discharged with ASA 100 mg only (G1) and the other group was additionally treated with 12–24 hr of heparin infusion and overlapping oral anticoagulation with coumadin for 6 months (G2). The two groups were comparable with respect to age, gender, coronary risk profile, clinical presentation, and angiographic lesion characteristics. Stents were implanted in 33% and 36% of the G1 and G2 patients, respectively. In‐hospital myocardial infarction occurred in 4% of the G1 and 3% of the G2 patients. One patient in G1 died of subacute stent thrombosis (day 3). Six‐month angiographic follow‐up was obtained in 90% of G1 patients and 94% of G2 patients. Restenosis occurred in 30% and 33% of the patients and mean diameter stenoses at follow‐up were 40% ± 28% and 39% ± 24%, respectively. Thrombin inhibition with heparin infusion followed by 6 months of oral anticoagulation did not reduce angiographic restenosis among patients undergoing PTCA with or without stent implantation. The occurrence of acute ischemic complications was also comparable in the two groups. Cathet Cardiovasc Intervent 2002;55:315–320. © 2002 Wiley‐Liss, Inc.
An unusual case of left internal mammary artery ostial disease: Clarifying role of intravascular ultrasound
Authors: Tantibhedhyangkul Wiwun , Laskey Warren K.
Published: August 2002

Stenosis at the origin of the left internal mammary artery graft is rare. We present a case with a suspected stenosis involving the origin of the left internal mammary artery that conventional angiography failed to demonstrate convincingly. Intravascular ultrasound illustrated a severe stenosis and the patient underwent successful stenting of the left internal mammary artery origin. The intravascular ultrasound finding of a dissection flap, just distal to the left internal mammary artery origin, suggests that local trauma to the vessel from prior catheterization procedures may have been responsible for the progressive narrowing at the left internal mammary artery ostium. Cathet Cardiovasc Intervent 2002;55:369–372. © 2002 Wiley‐Liss, Inc.
Small sample issues for microarray‐based classification
Authors: Dougherty Edward R.
Published: August 2002

In order to study the molecular biological differences between normal and diseased tissues, it is desirable to perform classification among diseases and stages of disease using microarray‐based gene‐expression values. Owing to the limited number of microarrays typically used in these studies, serious issues arise with respect to the design, performance and analysis of classifiers based on microarray data. This paper reviews some fundamental issues facing small‐sample classification: classification rules, constrained classifiers, error estimation and feature selection. It discusses both unconstrained and constrained classifier design from sample data, and the contributions to classifier error from constrained optimization and lack of optimality owing to design from sample data. The difficulty with estimating classifier error when confined to small samples is addressed, particularly estimating the error from training data. The impact of small samples on the ability to include more than a few variables as classifier features is explained. Copyright © 2001 John Wiley & Sons, Ltd.
Why more ‘quality time’ is not on the top of children's lists: the ‘qualities of time’ for children1
Authors: Christensen Pia Haudrup
Published: August 2002

For many years the everyday reality of working parents and their children has been captured in notions of ‘quality time’ versus ‘quantity time’. On the one hand it is suggested that what families need is ‘more time’ for parents to spend together with their children and less time working. On the other hand this has been countered with arguments saying that attention has to be paid to how parents spend their time together with their children. As a result quality time is often presented through idealised images of ‘happy families’. Quality time is seen as parents engaging with their children in particular activities or outdoor excursions that create and maintain family enjoyment, care and togetherness. However, such debates are based on assumptions of what would be ‘good’ for today's children and neglect the perspective of children themselves. This paper draws on field research carried out with 10–11‐year‐old children on their understandings and use of time in an urban and a rural setting in the north of England. The paper points to five ‘qualities of time’ identified by children. These qualities suggest that children's views of time spent with their families cannot be seen as separate from the time they spend with friends, at school and on their own. The paper argues that the quality/quantity time conundrum needs replacing by fuller and more representative accounts of the varied aspects of time that matter for children. These need to be situated in the processes through which family, school and work life take place on a daily basis and in relation to children's life course. Copyright © 2002 John Wiley & Sons, Ltd.
Asymmetric addition of allyltrimethylsilane to N‐tosylimine of (1R)‐8‐phenylmenthyl glyoxylate
Authors: Kulesza Anna , Jurczak Janusz
Published: August 2002

The addition of allyltrimethylsilane to chiral N‐tosylimine derived from (1R)‐8‐phenylmenthyl glyoxylate is discussed. Various Lewis acids were applied in order to postulate the stereochemical model for this type of nucleophilic addition. Chirality 13:634–635, 2001. © 2001 Wiley‐Liss, Inc.
Expression of constructs of the neuronal isoform of myosin‐Va interferes with the distribution of melanosomes and other vesicles in melanoma cells
Authors: da Silva Bizario João Carlos , Nascimento Alexandra Aparecida da Cunha , Casaletti Luciana , Patussi Eliana Valéria , Chociay Maria Fernanda , Larson Roy Edward , Espreafico Enilza Maria
Published: August 2002

Myosin‐Va has been implicated in melanosome translocation, but the exact molecular mechanisms underlying this function are not known. In the dilute, S91 melanoma cells, melanosomes move to the cell periphery but do not accumulate in the tips of dendrites as occurs in wild‐type B16 melanocytes; rather, they return and accumulate primarily at the pericentrosomal region in a microtubule‐dependent manner. Expression of the full‐length neuronal isoform of myosin‐Va in S91 cells causes melanosomes to disperse, occupying a cellular area approximately twice that observed in non‐transfected cells, suggesting a partial rescue of the dilute phenotype. Overexpression of the full tail domain in S91 cells is not sufficient to induce melanosome dispersion, rather it causes melanosomal clumping. Overexpression of the head and head‐neck domains of myosin‐Va in B16 cells does not alter the melanosome distribution. However, overexpression of the full tail domain in these cells induces melanosome aggregation and the appearance of tail‐associated, aggregated particles or vesicular structures that exhibit variable degrees of staining for melanosomal and Golgi β‐COP markers, as well as colocalization with the endogenous myosin‐Va. Altogether, the present data suggest that myosin‐Va plays a role in regulating the direction of microtubule‐dependent melanosome translocation, in addition to promoting the capture of melanosomes at the cell periphery as suggested by previous studies. These studies also reinforce the notion that myosin‐V has a broader function in melanocytes by acting on vesicular targeting or intracellular protein trafficking. Cell Motil. Cytoskeleton 51:57–75, 2002. © 2002 Wiley‐Liss, Inc.
Orbitomedial prefrontal cortical projections to hypothalamus in the rat
Authors: Floyd Nicole S. , Price Joseph L. , Ferry Amon T. , Keay Kevin A. , Bandler Richard
Published: August 2002

A previous study in the rat revealed that distinct orbital and medial prefrontal cortical (OMPFC) areas projected to specific columns of the midbrain periaqueductal gray region (PAG). This study used anterograde tracing techniques to define projections to the hypothalamus arising from the same OMPFC regions. In addition, injections of anterograde and retrograde tracers were made into different PAG columns to examine connections between hypothalamic regions and PAG columns projected upon by the same OMPFC regions. The most extensive patterns of hypothalamic termination were seen after injection of anterograde tracer in prelimbic and infralimbic (PL/IL) and the ventral and medial orbital (VO/MO) cortices. Projections from rostral PL/IL and VO/MO targeted the rostrocaudal extent of the lateral hypothalamus, as well as lateral perifornical, and dorsal and posterior hypothalamic areas. Projections arising from caudal PL/IL terminated within the dorsal hypothalamus, including the dorsomedial nucleus and dorsal and posterior hypothalamic areas. There were also projections to medial perifornical and lateral hypothalamic areas. In contrast, it was found that anterior cingulate (AC), dorsolateral orbital (DLO), and agranular insular (AId) cortices projected to distinct and restricted hypothalamic regions. Projections arising from AC terminated within dorsal and posterior hypothalamic areas, whereas DLO and AId projected to the lateral hypothalamus. The same OMPFC regions also projected indirectly, by means of specific PAG columns, to many of the same hypothalamic fields. In the context of our previous findings, these data indicate that, in both rat and macaque, parallel but distinct circuits interconnect OMPFC areas with specific hypothalamic regions, as well as PAG columns. J. Comp. Neurol. 432:307–328, 2001. © 2001 Wiley‐Liss, Inc.
Approximation of variable density incompressible flows by means of finite elements and finite volumes
Authors: Fraigneau Yann , Guermond Jean‐Luc , Quartapelle Luigi
Published: August 2002

This work describes a projection method for approximating incompressible viscous flows of non‐uniform density. It is shown that unconditional stability in time is possible provided two projections areperformed per time step. A finite element implementation and a finite volume one are described and compared. The performance of the two methods are tested on a Rayleigh–Taylor instability. We show that the considered problem has no inviscid smooth limit; hence confirming a conjecture by Birkhoffstating that the inviscid problem is not well‐posed. Furthermore, we show that at even moderate Reynolds numbers, this problem is extremely sensitive to mesh refinement and to the numerical method adopted. Copyright © 2001 John Wiley & Sons, Ltd.
Hemopoietic stem and precursor cell analysis in umbilical cord blood using the sysmex SE‐9000 IMI channel
Authors: Kraai R. , Reymer A. G. F. , Brouwer‐Mandema G. G. , van Beckhoven J. M. , Hoogeboom M. , le Cessie S. , Kluin‐Nelemans J. C.
Published: August 2002

Circulating hematopoietic progenitor cells (HPCs) are routinely measured by flow cytometry using CD34 expression. As an alternative, the “immature information” (IMI) channel measurement of the automated hematology analyzer Sysmex SE machines was developed. We tested the IMI channel HPC method with umbilical cord blood specimens. The IMI‐HPCs were compared with CD34 counts and numbers of colony‐forming units (CFUs). The IMI‐HPC data were reproducible and dilution experiments yielded a log‐linear relationship. The mean percentage of CD34+ cells in 50 umbilical cords was 0.43 versus 0.11 of HPCs in the IMI channel (correlation coefficient r = 0.67). Absolute numbers yielded 96.79 × 106/L CD34+, 33.17 × 106/L IMI‐HPC, and 35.04 × 106/L CFU‐HPC. Receiver operating characteristics curves were made at various cutoff levels for CD34+ cells to visualize sensitivity and specificity profiles. With median values of 13.56 × 106/L for IMI‐HPC and 20 × 106/L for CD34+ as cutoff points (the levels used in the laboratory to start stem cell pheresis), the percentage of false‐negative observations was 70.4%. To exclude the influence of storage time, tests were repeated until 72 h after umbilical cord collection. Total white blood cell count decreased in most cases, whereas absolute number of IMI‐HPC tended to increase in time. In conclusion, if HPC measurements in the IMI channel are used to monitor circulating stem cells during mobilization, one has to be aware of a very low correlation between these results and those of other methods such as CD34+ analysis and colony growth. False‐negative results do occur, but if events are seen in the IMI channel, this simple monitoring technique is useful to predict the presence of circulating stem cells. Cytometry (Comm. Clin. Cytometry) 46:114–118, 2001. © 2001 Wiley‐Liss, Inc.
Clinical, imaging, lesion, and genetic approaches toward a model of cognitive control
Authors: Casey B. J. , Tottenham Nim , Fossella John
Published: August 2002

The ability to suppress or override competing attentional and behavioral responses is a key component of cognitive processes. This ability continues to develop throughout childhood and appears to be disrupted in a number of childhood disorders (e.g., attention deficit/hyperactivity disorder and Tourette syndrome). At least two brain regions have been implicated repeatedly in these disorders—the frontal lobes and the basal ganglia. The common problem in cognitive control and overlap in implicated brain regions across disorders suggest a single underlying biological mechanism. At the same time, the distinct symptomatology observed across these disorders suggests multiple mechanisms are at play. This article presents converging evidence from clinical, neuroimaging, lesion, and genetic studies to provide a mechanistic model of cognitive control whereby the basal ganglia are involved in inhibition of competing actions and the frontal cortex is involved in representing the relevant thoughts and guiding the appropriate behaviors. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 237–254, 2002. DOI 10.1002/dev.10030
Vanadate disrupts mammary gland development in whole organ culture
Authors: Gallo‐Hendrikx Eleanor , Murray Stephen A. , Vonderhaar Barbara K. , Xiao Zhi‐Xiong Jim
Published: August 2002

Protein tyrosine kinases and phosphatases are signaling molecules involved in all aspects of development, including proliferation, differentiation, and apoptosis. How disruption of protein tyrosine phosphatase affects mammary gland development is not entirely clear. We examined the effects of sodium vanadate, which is known to primarily inhibit tyrosine phosphatases, in mouse mammary gland development in whole organ culture. Mammary epithelial differentiation was effectively inhibited by vanadate in a dose‐dependent manner as indicated by lack of epithelial alveoli compared to the contralateral non‐treated gland controls. Mammary glands in the differentiation medium after four days in the presence of vanadate did not differentiate into alveoli. Instead, they exhibited prominent terminal end buds and lost the distinctive epithelial structures. The inhibitory effect of vanadate on mammary epithelial cell differentiation was irreversible after one day of treatment. Immunohistochemical staining for PCNA (Proliferating Cell Nuclear Antigen) showed that vanadate‐treated glands exhibited elevated proliferation signals in the differentiation medium. Expression of β‐casein protein in the vanadate‐treated glands decreased dramatically and progressively. Short‐term exposure (up to 72 hours) of mammary glands to vanadate resulted in an increase in mammary epithelial cell density and loss of organization of the mammary structures. TUNEL assay of mammary glands with prolonged exposure to vanadate revealed widespread apoptosis. Furthermore, some cells were still proliferating or expressing β‐casein after prolonged exposure to vanadate. Taken together, these data indicate that vanadate treatment blocks mammary epithelial cell differentiation and promotes abnormal proliferation and apoptosis, likely through the inhibition of protein tyrosine phosphatase‐mediated signaling. © 2001 Wiley‐Liss, Inc.
Selective expression of the small GTPase RhoB in the early developing mouse lens
Authors: Maddala Rupalatha , Peng You‐Wei , Rao P. Vasantha
Published: August 2002

This report describes the expression and distribution pattern of RhoB GTPase in the developing mouse lens. RhoB expression was confirmed by sequencing an reverse transcriptase‐polymerase chain reaction–generated DNA fragment of RhoB. Immunohistochemical analysis of RhoB revealed expression in the lens vesicle (both anterior and posterior vesicle) at embryonic day (E) 11.5, and in the epithelium and primary fibers of the E14.5 lens. Compared with the neonatal stage (day 1), where RhoB is detected in the entire lens (epithelium, primary, and secondary fibers), expression of this protein is restricted to the epithelial and outer cortical secondary fibers in postnatal lenses (from day 7 to day18). Interestingly, in E11.5 and E14.5 lenses, RhoB is localized predominantly in the lens, but not detectable in the retina, cornea, or other ocular tissues. RhoB expression appears to be down‐regulated in the postnatal lens with concomitant up‐regulation in the retina and cornea, compared with earlier stages of development (eyes of E11.5, E14.5, and neonatal mice). This study reveals the selective expression of RhoB in the lens during early eye development and suggests a potential role for this small GTPase in cytoskeletal reorganization associated with lens epithelial cell elongation and differentiation. © 2001 Wiley‐Liss, Inc.
Stretching the boundaries: strategic perceptions of intragroup variability
Authors: Rubin Mark , Hewstone Miles , Voci Alberto
Published: August 2002

We hypothesised that people would strategically alter their perceived intragroup variability on ingroup‐threatening traits in order to maintain positive perceptions of their self and their ingroup. Specifically, we predicted that people would perceive (1) greater relative outgroup homogeneity and (2) greater general intragroup variability on ingroup negative and outgroup positive traits. We confirmed the outgroup homogeneity prediction in a minimal group experiment (N=80) and a gender group experiment (N = 164). In a second gender group experiment (N = 137), we found that ingroup size moderated this effect: only minority group members showed the predicted pattern of outgroup homogeneity. Evidence for the general intragroup variability prediction was less conclusive. We discuss the results in terms of variability strategies. Copyright © 2001 John Wiley & Sons, Ltd.
Central nervous system perivascular cells are immunoregulatory cells that connect the CNS with the peripheral immune system
Authors: Williams Kenneth , Alvarez Xavier , Lackner Andrew A.
Published: August 2002

Perivascular cells are a heterogeneous population found in the central nervous system (CNS) and the peripheral nervous system (PNS). Several terms are used for these cells, including perivascular cells, perivascular macrophages, perivascular microglia, fluorescent granular perithelial cells (FGP), or Mato cells. Different terminology used may reflect subpopulations of perivascular cells within different anatomic regions and experimental paradigms, neuropathological conditions, and species studied. Different terminology also points to the lack of clear consensus of what cells are perivascular cells in different disease states and models, especially with breakdown of the blood‐brain barrier (BBB). Despite this, there is consensus that perivascular cells, although a minor component of the CNS, are important immunoregulatory cells. Perivascular cells are bone marrow derived, continuously turn over in the CNS, and are found adjacent to CNS vessels. Thus, they are potential sensors of CNS and peripheral immune system perturbations; are activated in models of CNS inflammation, autoimmune disease, neuronal injury and death; and are implicated as phagocytic and pinocytotic cells in models of stroke and hypertension. Recent evidence from our laboratory implicate perivascular cells as primary targets of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infection in the CNS of humans and macaques. This article reviews current knowledge of perivascular cells, including anatomic location and nomenclature and putative immunoregulatory roles, and discusses new data on the infection of these cells by SIV, their accumulation after SIV infection, and a possible role of the immune system in SIV encephalitis. GLIA 36:156–164, 2001. © 2001 Wiley‐Liss, Inc.
MRI white matter hyperintensities, 1H‐MR spectroscopy and cognitive function in geriatric depression: a comparison of early‐ and late‐onset cases
Authors: Murata Tetsuhito , Kimura Hirohiko , Omori Masao , Kado Hirotsugu , Kosaka Hirotaka , Iidaka Tetsuya , Itoh Harumi , Wada Yuji
Published: August 2002

Background and Objectives

Geriatric depression is often thought to differ from that at other times of adulthood. Recently, several studies have shown that the incidence of white matter hyperintense lessions identified by brain MRI is higher in patients with geriatric depression than in healthy elderly subjects, but a consensus has not yet been reached on the relationship between the severity of white matter lesions and either cognitive impairment or depressive symptoms.

Method

Forty‐seven patients aged 50 to 75 years with major depression were divided into two groups based on age at onset of depression: early‐onset (< 50 years) group (20 patients; mean age, 62.7 ± 6.7) and late‐onset (≥50 years) group (27 patients; mean age, 65.6 ± 5.4). The severity of hyperintense white matter lesions on MRI was classified by region, then a proton magnetic resonance spectroscopy (1H‐MRS) focusing on the white matter of the frontal lobes, multidimensional neuropsychological tests and evaluation of depressive symptoms were conducted.

Results

The severity of the deep white matter lesions, the deterioration of cognitive function related to subcortical/frontal brain system and clinician‐rated depressive symptoms were all more pronounced in the late‐onset group compared with those in the early‐onset group. It was further observed that the more severe the deep white matter lesions, the lower the levels of N‐acetylaspartate/creatine. With the age of onset as the covariate, the patients with moderate deep white matter lesions had more pronounced cognitive impairment and clinician‐rated depressive symptoms than those with none and/or mild lesions.

Conclusion

These results suggest that subcortical/frontal type cognitive impairment and the persistence of depressive symptoms in geriatric depression is related to moderate deep white matter lesions more often complicated in the late‐onset group. The 1H‐MRS findings were suggested to be a useful indicator of neuronal/axonal loss in the white matter of the frontal lobes which precedes cognitive impairment. Copyright © 2001 John Wiley & Sons, Ltd.
Induction of interleukin‐1β and interleukin‐6 mRNA by low doses of ionizing radiation in macrophages
Authors: Hosoi Yoshio , Miyachi Hideo , Matsumoto Yoshihisa , Enomoto Atsushi , Nakagawa Keiichi , Suzuki Norio , Ono Tetsuya
Published: August 2002

We have previously reported the antimetastatic effects and augmentation of immune responses, which would be a mechanism of the antimetastatic effects, of 0.1 to 0.2 Gy total body irradiation. To elucidate the cellular mechanisms of the augmentation of immune response, we investigated the effects of low‐dose irradiation on gene expression of interleukin‐1β (IL‐1β) and IL‐6 using mouse peritoneal macrophages in vitro. Absolute mRNA quantification was carried out using competitive polymerase chain reaction. Gene expression of IL‐1β and IL‐6 was increased 1 to 2 hr after 2.0 Gy irradiation and then decreased to below the basal expression level 4 hr after irradiation. Irradiation with 0.1 Gy increased IL‐6 expression 2 hr after irradiation, but it did not affect IL‐1β expression. Downregulation of IL‐1β and IL‐6 observed 4 hr after 2.0 Gy irradiation was not observed with 0.1 Gy irradiation. The protein kinase C (PKC) inhibitor H7 and the phosphatidylinositol 3‐kinase (PI3‐kinase) inhibitor wortmannin inhibited induction of IL‐1β and IL‐6 expression, which suggests that radiation‐induced IL‐1β and IL‐6 expression is achieved by PKC‐ and PI3‐kinase‐mediated signaling. © 2001 Wiley‐Liss, Inc.
Lack of adverse effects on fertility of female cd‐1 mice exposed to repetitive intravaginal gel–microemulsion formulation of a dual‐function anti‐HIV agent: aryl phosphate derivative of bromo‐methoxy‐zidovudine (compound WHI‐07)
Authors: D'Cruz Osmond J. , Uckun Fatih M.
Published: August 2002

5‐bromo‐6‐methoxy‐5,6‐dihydro‐3′‐azidothymidine‐5′‐(p‐bromophenyl) methoxyalaninyl phosphate (WHI‐07), a novel bromo‐methoxy‐substituted aryl phosphate derivative of zidovudine (ZDV), is a potent dual‐function contraceptive agent with anti‐HIV activity. Its potential for reproductive toxicity was assessed in a series of experiments using CD‐1 mice under the conditions of its intended use as an intravaginal microbicide. Female CD‐1 mice were exposed intravaginally to a gel–microemulsion formulation containing 0%, 0.5%, 1.0% or 2.0% WHI‐07 for up to 13 weeks. On a molar basis, these concentrations represent 1400–5700 times its in vitro spermicidal IC50 and 1.4–5.7(×106) times its in vitro anti‐HIV IC50. We examined the effects of intravaginally administered WHI‐07 on: ovulation efficiency; in vivo fertilization and early embryonic, fetal development; and reproductive outcome, including neonatal survival and pup development. Compound WHI‐07 was administered intravaginally during superovulation, organogenesis and prior to mating for 5 and 10 consecutive days and for 13 weeks, respectively. Mice were evaluated for ovulation efficiency and fertilization rate and cleavage 14 and 40 h after human chorionic gonadotropin (hCG) injection, respectively. Pregnant mice were administered 2% WHI‐07 intravaginally during gestation days (GD) 6–15 and measures of teratogenicity were evaluated on GD 17. For short‐term toxicity study, mice were given intravaginal treatment of gel–microemulsion containing 0%, 0.5%, 1.0% and 2.0% WHI‐07 for 13 weeks and then mated with untreated males to evaluate potential reproductive and developmental effects. Repeated intravaginal exposure of mice to 2% WHI‐07 had no adverse effects on ovulation response, mean number of eggs recovered or the percentage of eggs fertilized or cleaved. No evidence of reproductive toxicity, fetal toxicity or teratogenicity was found following repetitive intravaginal application of 2% WHI‐07 during the period of organogenesis. Furthermore, repeated intravaginal exposure of mice to 0.5–2.0% WHI‐07 for 13 weeks had no adverse effect on the subsequent reproductive capability, perinatal outcome or growth and development of the offspring. Compound WHI‐07 shows unique clinical potential as a safe, dual‐function vaginal contraceptive for curbing mucosal and perinatal HIV transmission. Copyright © 2001 John Wiley & Sons, Ltd.