bluuebunny/crossref_metadata_2025 huggingface dataset:
ABCB6 (MTABC3) excluded as the causative gene for the growth retardation syndrome with aminoaciduria, cholestasis, iron overload, and lactacidosis
Authors: Visapää Ilona , Fellman Vineta , Lanyi Lisa , Peltonen Leena
Published: August 2002

GRACILE syndrome (growth retardation, aminoaciduria, cholestasis, iron overload, lactacidosis, and early death; OMIM 603358) is a rare metabolic disorder with autosomal recessive mode of inheritance. So far it has been diagnosed only in patients with Finnish ancestors. The GRACILE locus has been positioned to a restricted region of chromosome 2q33–37, but the causative gene remains to be identified. The ABCB6 gene, involved in iron homeostasis, mitochondrial respiratory function, and maintenance of the stability of mitochondrial DNA, has been positioned to this same chromosomal region, and advocated in literature as a highly probable candidate gene for the syndrome on both functional and positional grounds. We carried out sequence and quantitative expression analyses to detect potential disease‐associated mutations in the ABCB6 gene. No mutations in the coding region of ABCB6 were found, and the expression level of ABCB6 in patient fibroblasts was found to be comparable to controls. Haplotype analysis of the critical DNA region provided evidence for positional exclusion also. Based on these data, ABCB6 is not the causative gene for GRACILE syndrome. © 2002 Wiley‐Liss, Inc.
Craniosynostosis, telecanthus, scalp hair abnormalities, and sensorineural deafness in two sibs
Authors: Mégarbané André , Hersh Joseph H. , Chouery Eliane , Fabre Michel
Published: August 2002

A sister and a brother with anomalous skull configuration, facial abnormalities, abnormal scalp hair growth, sensorineural hearing loss and, in the boy, proven craniosynostosis, severe mental retardation, and autism were reported in 1986 in an abstract by Hersh et al. We reexamined this family and here review the literature focusing on the major clinical findings, and suggest that their clinical manifestations may represent a previously unreported syndrome. © 2002 Wiley‐Liss, Inc.
Relationship between Taq1 A dopamine D2 receptor (DRD2) polymorphism and prolactin response to bromperidol
Authors: Mihara Kazuo , Suzuki Akihito , Kondo Tsuyoshi , Yasui‐Furukori Norio , Ono Shingo , Otani Koichi , Kaneko Sunao , Inoue Yoshimasa
Published: August 2002

The dopamine D2 receptor (DRD2) gene has a Taq1 A restriction fragment length polymorphism yielding two alleles, A1 and A2. We have previously shown that female patients with the A1 allele show greater prolactin response to nemonapride, a selective antagonist for D2‐like dopamine receptors, in schizophrenic patients. In the present study, the relationship between this polymorphism and prolactin response to bromperidol was investigated in 32 untreated schizophrenic inpatients (16 males, 16 females). The daily dose of bromperidol was fixed at 6 (n = 10), 12 (n = 13), or 18 mg (n = 9) during a 2‐week treatment period. Taq1 A genotypes were determined by PCR method. Plasma prolactin concentration was measured by radioimmunoassay. Plasma concentration of bromperidol was measured by HPLC method. The subjects were divided into four subgroups by gender and the genotypes, i.e., 10 males and 11 females with the A1 allele, 6 males and 5 females with no A1 allele. The females with the A1 allele had the highest Δ prolactin (the change from the pretreatment concentration)/bromperidol concentration ratio among the other groups (P < 0.05). The present study thus suggests that female patients with the A1 allele show greater prolactin response to bromperidol, who may have a high risk for adverse effects associated with neuroleptic‐induced hyperprolactinemia. © 2001 Wiley‐Liss, Inc.
Lack of association between HoxA1 and HoxB1 gene variants and autism in 110 multiplex families
Authors: Li Jun , Tabor Holly K. , Nguyen Loan , Gleason Christopher , Lotspeich Linda J. , Spiker Donna , Risch Neil , Myers Richard M.
Published: August 2002

A recent report suggested that the HoxA1 and/or HoxB1 genes play a role in susceptibility to autism. To determine whether these findings could be confirmed, we screened these genes for DNA polymorphisms by sequencing all exons in 24 individuals with autism. We identified the same sequence variants in the genes that appeared in this report, which include one single‐base substitution variant in HoxA1 and a common haplotype in HoxB1. We performed an association study by applying the transmission disequilibrium test to detect possible association of these variants to autism in 110 multiplex families. Our results demonstrated no deviation from the null hypothesis of no association. We have also separately examined transmissions within individual mating types, for paternal versus maternal alleles, to affected versus unaffected children, and for transmission to affected boys versus girls. None of these subsets revealed significant deviation from the null expectation. Our interpretation of these findings is that it is unlikely that HoxA1 and HoxB1 play a significant role in the genetic predisposition to autism. © 2001 Wiley‐Liss, Inc.
Effects of food availability on serum insulin and lipid concentrations in free‐ranging baboons
Authors: Kemnitz Joseph W. , Sapolsky Robert M. , Altmann Jeanne , Muruthi Philip , Mott Glen E. , Stefanick Marcia L.
Published: August 2002

The relationship between food availability and metabolic physiology was studied in groups of free‐ranging baboons (Papio spp.) living in the Amboseli National Park and the Masai Mara National Reserve of Kenya. Three groups subsisted entirely on natural forage, while two other groups lived near tourist facilities and often consumed food wastes from these lodges. The refuse provided a very accessible food source with relatively high caloric density. Consumption of the refuse was associated with reduced locomotion. Sexually mature individuals from all five groups were sedated surreptitiously in the early morning and blood samples were collected. Compared to animals foraging exclusively in the wild, animals that supplemented their diet with the refuse items had two‐ to threefold elevations in serum insulin concentrations, as well as increased total cholesterol (C), HDL‐C, and VLDL+LDL‐C levels. No sex differences in physiological measures were observed except in body mass. Elevated serum insulin, and cholesterol and lipoprotein concentrations influence the development of cardiovascular disease and have been shown to be subject to dietary manipulation and exercise under controlled conditions. The present results suggest potentially deleterious effects of a highly accessible, calorically dense food source, and associated reduction of physical activity for baboons living in an otherwise natural environment. Am. J. Primatol. 57:13–19, 2002. © 2002 Wiley‐Liss, Inc.
Multiple sirehood in free‐ranging twin rhesus macaques (Macaca mulatta)
Authors: Bercovitch Fred B. , Widdig Anja , Berard John D. , Nürnberg Peter , Kessler Matt J. , Schmidtke Jörg , Trefilov Andrea , Krawczak Michael
Published: August 2002

Rhesus macaque females regularly copulate with a number of partners, and produce a single offspring per reproductive cycle in over 99% of cases. We used genotyping of 10 STR markers to determine paternity in the Cayo Santiago population of rhesus macaques. About 1,500 monkeys have been analyzed to date, with their marker genotypes entered into a computerized database. These data enable us to report the first documented case in any cercopithecine nonhuman primate species of the production of twin offspring sired by different males. Am. J. Primatol. 57:31–34, 2002. © 2002 Wiley‐Liss, Inc.
Melatoninergic neuroprotection of the murine periventricular white matter against neonatal excitotoxic challenge
Authors: Husson Isabelle , Mesplès Bettina , Bac Pierre , Vamecq Joseph , Evrard Philippe , Gressens Pierre
Published: August 2002

Periventricular leukomalacia is one of the main causes of cerebral palsy. Perinatal white matter lesions associated with cerebral palsy appears to involve glutamate excitotoxicity and excess free radical production. When injected intracerebrally into newborn mice, the glutamatergic analog ibotenate induces white matter cysts mimicking human periventricular leukomalacia. Melatonin acts on specific receptors. It also exhibits intrinsic free radical scavenging properties. The goal of the present study is to determine whether melatonin can protect against excitotoxic lesions induced by ibotenate in newborn mice. Mice that received intraperitoneal melatonin had an 82% reduction in size of ibotenate‐induced white matter cysts when compared with controls. Although melatonin did not prevent the initial appearance of white matter lesions, it did promote secondary lesion repair. Axonal markers supported the hypothesis that melatonin induced axonal regrowth or sprouting. The protective effects of melatonin were suppressed by coadministration of luzindole, a melatonin receptor antagonist. Forskolin, an adenylate cyclase activator, prevented the protective effects of melatonin; inhibitors of protein kinase C and mitogen‐associated protein kinase had no detectable effect. Melatonin and derivatives that block cAMP production through activation of melatonin receptors could represent new avenues for treating human periventricular leukomalacia.
Complex immunomodulatory effects of interferon‐β in multiple sclerosis include the upregulation of T helper 1‐associated marker genes
Authors: Wandinger Klaus‐Peter , Stürzebecher Claus‐Steffen , Bielekova Bibiana , Detore Greg , Rosenwald Andreas , Staudt Louis M. , McFarland Henry F. , Martin Roland
Published: August 2002

Multiple sclerosis (MS) is considered an autoimmune disease that is mediated by proinflammatory T helper‐1 lymphocytes. The putative mechanism of interferon‐β (IFN‐β), an approved treatment for MS, includes the inhibition of T‐cell proliferation, blocking of blood‐brain‐barrier opening and T‐cell transmigration into the brain via interference with cell adhesion, and the upregulation of anti‐inflammatory (TH2) cytokines. In the present study, a gene expression analysis of IFN‐β‐treated peripheral blood mononuclear cells by cDNA microarray documents the broad effects of IFN‐β that are not purely anti‐inflammatory. Specifically, we addressed the effect of IFN‐β on T helper‐1 differentiation‐ or lineage markers such as the IL‐12 receptor β2 chain and the chemokine receptor CCR5 that have been implicated in the pathogenesis of MS. Both markers were significantly upregulated in vitro and in vivo under IFN‐β therapy, supporting that this cytokine exerts complex effects on the immune system. The combination of cDNA microarray and quantitative polymerase chain reaction will expand our knowledge of the immunological effects of such pleiotropic agents as IFN‐β, may provide a key to why certain patients fail to respond, and eventually influence our view of the disease pathogenesis.
Relationship of the extended tau haplotype to tau biochemistry and neuropathology in progressive supranuclear palsy
Authors: Liu Wan‐Kyng , Le Tien V. , Adamson Jennifer , Baker Matthew , Cookson Natalie , Hardy John , Hutton Michael , Yen Shu‐Hui , Dickson Dennis W.
Published: August 2002

Two extended haplotypes of the tau gene (H1 and H2) have been described. The frequency of H1 haplotype is increased in progressive supranuclear palsy (PSP). PSP is associated with filamentous tau lesions in neurons and glia, which are reportedly composed exclusively of tau isoforms with four repeats in the microtubule‐binding domain (4R tau). To determine the influence of the tau haplotype on tau isoform composition and neuropathology, we studied 25 PSP cases and 6 Alzheimer's disease patients matched for age, sex, and postmortem delay. In the basal ganglia, tau and amyloid burdens were determined to see if there was an effect of concurrent Alzheimer‐type pathology, and the ratio of 4R to 3R tau was measured in detergent‐insoluble tau fractions. Insoluble tau from PSP was not composed exclusively of 4R tau. All brains had a mixture of 4R and 3R tau, but the ratio was different in Alzheimer's disease and PSP. In Alzheimer's disease there was less 4R than 3R tau, whereas the ratio was reversed in PSP. In PSP cases with concurrent Alzheimer‐type pathology, the ratio of 4R to 3R was intermediate between Alzheimer's disease and PSP. The H1 haplotype had no effect on the 4R to 3R ratio or on tau and amyloid burdens. In summary, the H1 haplotype does not have a major influence on the pathological or biochemical phenotype of PSP.
Biotransformation of arsenite in freshwater food‐chain models
Authors: Suhendrayatna  , Ohki Akira , Maeda Shigeru
Published: August 2002

Bioaccumulation and biotransformation of arsenite by freshwater organisms consisting Daphnia magna, Neocaridina denticulata and Tilapia mossambica has been studied. When organisms were exposed to a medium containing arsenite, the total arsenic concentration accumulated by the organisms increased with an increase in the arsenic concentration in the medium. The order of total arsenic accumulation by freshwater organisms was D. magna > N. denticulata > T. mossambica. Bioaccumulation and biotransformation of arsenite in three‐step laboratory food‐chain models was investigated by feeding a diet of arsenite‐dosed alga (Chlorella vulgaris) to herbivorous grazers (D. magna and N. denticulata) and then the herbivores were fed to carnivorous fish (T. mossambica and Zacco platypus). Total arsenic concentrations in the organisms decreased by an order of magnitude for each step in the food chain. Arsenite and arsenate were accumulated as the predominant arsenic species in organisms. Little methylation of arsenic in organisms occurred at each step in the food chain. Copyright © 2001 John Wiley & Sons, Ltd.
Silylation–desilylation of quinones and their derivatives
Authors: Bakola‐Christianopoulou Maria N.
Published: August 2002

The silylation of quinones and their substituted derivatives for the protection of the reactive quinonic moiety and/or reactive substituents (in particular hydroxyl groups) is discussed in view of the wide applicability of the reaction for synthetic, biological and analytical purposes. Furthermore, the most common and efficient methods for the subsequent desilylation of the silylated quinones and their derivatives to the parent quinones or to the corresponding hydroquinones are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Isothermal curing by dynamic mechanical analysis of three epoxy resin systems: Gelation and vitrification
Authors: López J. , Ramírez C. , Torres A. , Abad M. J. , Barral L. , Cano J. , Díez F. J.
Published: August 2002

Times to gelation (tgel) and times to vitrification (tvit) during isothermal curing for the epoxy systems diglycidyl ether of bisphenol A (DGEBA)/1,3‐bisaminomethylcyclohexane (1,3‐BAC), tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM)/4‐4′‐diaminodiphenylsulfone (DDS), and TGDDM/epoxy novolac (EPN)/DDS were measured at different curing temperatures. This article reports on a method to determine tgel and tvit by dynamic mechanical analysis (DMA). Gelation was determined at the onset of the storage modulus or by the peak of the loss factor. Vitrification was defined as the curve of the storage modulus as the curve reached a constant level (endset) in DMA tests. The experimental values obtained for tgel and tvit were compared with values obtained by other experimental methods and with theoretical values (tgel's) or indirect determinations (tvit's). From kinetic analysis by differential scanning calorimetry, conversions corresponding to gelation were obtained for the three systems; this yielded a constant value for each system that was higher than theoretical value. Values of the apparent activation energies of the DGEBA/1,3‐BAC, TGDDM/DDS, and TGDDM/EPN/DDS epoxy systems were obtained from plots of tgel's against reciprocal temperatures. They were 53.2, 58.2, and 46.5 kJ/mol, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 78–85, 2002
Modification of epoxy resin by isocyanate‐terminated polybutadiene
Authors: Barcia Fábio L. , Abrahão Márcio A. , Soares Bluma G.
Published: August 2002

Hydroxy‐terminated polybutadiene was functionalized with isocyanate groups and employed in preparation of a block copolymer of polybutadiene and bisphenol A diglycidyl ether (DGEBA)‐based epoxy resin. The block copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy and size‐exclusion chromatography (SEC). Cured blends of epoxy resin and hydroxy‐terminated polybutadiene (HTPB) or a corresponding block copolymer were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMTA), and scanning electron microscopy (SEM). All modified epoxy resin networks presented improved impact resistance with the addition of the rubber component at a proportion up to 10 wt % when compared to the neat cured resin. The modification with HTPB resulted in milky cured materials with phase‐separated morphology. Epoxy resin blends with the block copolymer resulted in cured transparent and flexible materials with outstanding impact resistance and lower glass transition temperatures. No phase separation was discernible in blends with the block copolymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 838–849, 2002
Adsorption of Ni2+ from aqueous solutions by novel polyethyleneimine‐attached poly(p‐chloromethylstyrene) beads
Authors: Say Ridvan , Tuncel Ali , Denizli Adil
Published: August 2002

In this study Ni2+ adsorption properties of polyethyleneimine (PEI)‐attached poly(p‐chloromethylstyrene) (PCMS) beads were investigated. Spherical beads with an average size of 186 μm were obtained by the suspension polymerization of p‐chloromethylstyrene conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, PCMS beads had a specific surface area of 14.1 m2/g. PEI chains could be covalently attached onto the PCMS beads with equilibrium binding capacities up to 208 mg PEI/g beads, via a direct chemical reaction between the amine and chloro‐methyl groups. After PEI adsorption with 10% (w/w) initial PEI concentration, free amino content of PEI‐attached PCMS beads was determined as 0.91 mEq/g. PEI‐attached PCMS beads were utilized as adsorbents in the adsorption/desorption of Ni2+ ions from synthetic solutions. The adsorption process was fast; 90% of adsorption occurred within 90 min, and equilibrium was reached at around 2 h. Adsorption capacity was obtained to be 78.2 mg/g at a pH of about 6.0. The chelating beads can be easily regenerated by 0.1 M HNO3 with higher effectiveness. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2467–2473, 2002
Physical and mechanical properties of Al(OH)3/polypropylene composites modified by in situ‐functionalized polypropylene
Authors: Mai Kancheng , Li Zhengjun , Qiu Yuxin , Zeng Hanmin
Published: August 2002

Al(OH)3/polypropylene (PP) composites modified by in situ‐functionalized polypropylene (FPP) were prepared by a one‐step melt‐extrusion process. The effect of in situ FPP on the crystallization and melting behavior, melt‐flow index, limiting oxygen index, thermal degradation, mechanical properties, and fracture morphology of Al(OH)3/PP composites was studied. Formation of in situ FPP resulted in a decreased crystallization temperature and melting point of PP in the composites, an increased melt‐flow index, and improved tensile and flexural strengths of Al(OH)3/PP composites, whereas the thermal degradation behavior and limiting oxygen index was not been influenced. The impact strength of the Al(OH)3/PP composites modified by in situ FPP depended upon the content of the initiator, dicumyl peroxide, and the monomer, acrylic acid. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2850–2857, 2002; DOI 10.1002/app.10269
Mechanochemical copolymerization of methyl methacrylate and styrene initiated by the grinding of quartz
Authors: Hasegawa Masahiro , Kimata Mitsumasa , Kobayashi Shun‐Itsu
Published: August 2002

The copolymerization of methyl methacrylate and styrene mechanochemically initiated by the grinding of quartz in the monomer mixture was investigated by using a vibrating ball mill. The effect of the grinding of quartz on the copolymerization was investigated by characterizing both the polymer formed and the ground quartz. The copolymerization proceeds apparently from the quartz grindings and was closely related to the total surface area of the ground quartz. The molecular weight distributions of the copolymers formed were unimodal as found in a homopolymer of only methyl methacrylate. It was clear from the composition analysis of the copolymer that the mechanochemical copolymerization of methyl methacrylate and styrene proceeded with a radical polymerization mechanism because of radicals on the quartz surface produced by the grinding. The monomer reactivity ratios obtained by the Fineman‐Ross method suggested that the copolymers formed were alternating copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2011–2017, 2002; DOI 10.1002/app.10544
Solid‐state 13C‐NMR and study of the subproducts obtained from corn industry
Authors: Mothé C. G. , Machado M. G. S. , Tavares M. I. B.
Published: August 2002

The two types of commercial corn flour subproducts from the Brazilian corn industry containing starch with low fat and with fat were investigated by solid‐state NMR techniques to improve their uses. From the NMR techniques used, it was characterized that after a treatment the quantity of fibers decreased. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1680–1685, 2002; DOI 10.1002/app.10547
Fine‐tuning the mechanical properties of hydroxyl‐terminated polybutadiene/ammonium perchlorate‐based composite solid propellants by varying the NCO/OH and triol/diol ratios
Authors: Hocaoğlu Özgür , Özbelge Tülay , Pekel Fikret , Özkar Saim
Published: August 2002

Changes in the mechanical properties of hydroxyl‐terminated polybutadiene/ammonium perchlorate‐based composite solid propellants were studied during the curing period with respect to variations in the crosslink density, which was predominantly determined by the equivalent ratio of diisocyanate to total hydroxyl (NCO/OH ratio) and the equivalent ratio of triol to diol (triol/diol ratio). For this purpose, 16 propellants were prepared in different compositions through changes in the NCO/OH ratios (0.81, 0.82, 0.83, and 0.85) for each triol/diol ratio (0.07, 0.09, 0.11, and 0.13) and were tested for their mechanical properties immediately after curing. The propellants with an NCO/OH ratio of 0.82 had minimum stress, modulus, and hardness with maximum strain capability, whereas the propellants with an NCO/OH ratio of 0.85 showed just the opposite behavior. Variations in the isocyanate level seemed to have more effect on the mechanical properties at higher triol/diol ratios. It was also concluded that the propellants with triol/diol–NCO/OH combinations of 0.11–0.83, 0.11–0.85, 0.13–0.81, 0.13–0.83, and 0.13–0.85 were not acceptable for upper stage case‐bonded rocket applications because of either high tensile strength or high modulus. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2072–2079, 2002; DOI 10.1002/app.10605
Synthesis and characterization of oligosalicylaldehyde‐graft‐oligoaniline and its beginning oligomers
Authors: Kaya İsmet , Vilayetoǧlu Adalet R.
Published: August 2002

Conjuge bonding oligosalicylaldehyde‐graft‐oligoaniline (OSA‐graft‐OA) was synthesized from the polycondensation reaction of oligosalicylaldehyde (OSA) with oligoaniline (OA). There were various functional groups such as OH, NH and CHN in the structure of the graft cooligomer. The physical properties of graft‐co‐oligomers such as melting temperature and solubility were studied: number‐average molecular weight, mass‐average molecular weight, and a polydispersity index of OA, OSA, and fractions of the graft cooligomers [(OSA‐graft‐OA)‐I] and [(OSA‐graft‐OA)‐II] were found to be 740, 780 g mol−1,1.05; 3700, 5990 g mol−1, 1.62; 990, 2770 g mol−1, 2.80 and 1300, 4100 g mol−1, 3.15, respectively. The FTIR and UV‐Vis spectra of the graft cooligomer were compared with those of beginning oligomers. The spectral analyses results showed that the OSA‐graft‐OA synthesized from the polycondensation reaction of aromatic amine with aldehyde that have long oligophenol macromolecule bonded each other with an azomethine bridge through oligophenylamine side chains. The thermal stability of the graft cooligomer and oligomers were measured by thermogravimetric analysis (TG) under an air atmosphere. According to TG analyses, the carboneous residues of the [(OSA‐graft‐OA)‐I) (soluble in ethanol) and (OSA‐graft‐OA)‐II) (soluble in toluene)] were 23 and 40%, respectively, at 1000°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 218–226, 2002
Synthesis, characterization, and properties of amphiphilic poly(ethyl acrylate) with uniform polyoxyethylene grafts
Authors: Xie Hong‐Quan , Liu Yan
Published: August 2002

Amphiphilic copolymers of ethyl acrylate (EA) with uniform polyoxyethylene (PEO) grafts were synthesized by copolymerization of EA with methacrylate terminated PEO macromer in benzene using azobisisobutyronitrile as the initiator. The effects of the molecular weight of the macromers, the charging weight ratio of the macromer to EA, the total monomer concentration, and the amount of initiator on the grafting efficiency (GE) were reported as was the molecular weight of the copolymers. The highest GE reached to above 90% and the molecular weight of the copolymers varied from (5–15) × 104. The reactivity ratio of EA with the macromer was determined to be 0.83. The graft copolymers were purified with extractions and the purified products were characterized with IR, 1H‐NMR, gel permeation chromatography, differential scanning calorimetry, and membrane osmometry. The average grafting number of the copolymer varied from 2 to 11. The glass‐transition temperature of the poly(EA) in the copolymer was increased because of the partial compatibility of the two components. The crystalline property, emulsifying property, and dilute solution viscosity of the graft copolymers, as well as ionic conductivity of their complexes with alkali metal salts, were studied. The emulsifying volume decreased with the increasing molecular weight of the PEO grafts. The addition of NaOH to the emulsion affected the emulsifying volume only slightly, whereas the addition of HCl changed the oil in water type emulsion into a water in oil type. The conductivity of the LiClO4 complex of the copolymer with an oxyethylene/Li ratio of 20 reached 3.7 × 10−5 S/cm at 27°C. The lower the crystallinity of the complex, the higher was the conductivity. The dilute solution viscosity showed the existence of intramolecular microphase separation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 903–912, 2001
Effects of nitrolignin on mechanical properties of polyurethane–nitrolignin films
Authors: Zhang Lina , Huang Jin
Published: August 2002

Polyurethane‐nitrolignin (PUNL), a new network polymer, was synthesized from a castor oil based–polyurethane (PU) prepolymer and nitrolignin (NL) with a weight‐average molecular weight of 20.6 × 104 and a content of 1.4–10%. The structure and miscibility of PUNL films prepared by solution casting were investigated by infrared spectroscopy and transmission electron microscopy. The results indicated that PUNL2 film, which had a 2.8% NL content, was the most miscible, and its tensile strength (σb) and breaking elongation (ϵb) were 2 times higher than that of PU film. The crosslink densities of PUNL films increased with the increase of NL content until about 3%, similar to the variety of the mechanical properties. Thermogravimetric analysis revealed that the thermal stability of PUNL films was slightly higher than that of PU. Covalent bonds occurred between PU prepolymer and the NL in the PUNL films, forming crosslink networks, which resulted in the enhancement of mechanical properties and thermal stability. NL has a far higher reactivity with PU than nitrocellulose. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1213–1219, 2001
Ionomer. I. The effect of woven glass mat reinforcement on tensile properties
Authors: Shonaike Gabriel O. , Sugahara T. , Murakami A.
Published: August 2002

An investigation was conducted on ionomer polymer. The ionomer pellets were molded into a thin sheet before fabrication into composites. The reinforcing agent used was woven glass mat. Before fabrication, the woven glass mat was treated with the following: 1. silane coupling agent for 5 min and dried at room temperature; 2. silane coupling agent for 5 min and dried in the oven at 110°C for 15 min; 3. Ultraviolet radiation for 5 min; and 4. silane (oven dried + ultraviolet). The composites were fabricated at various pressure, time, and temperature. An ideal processing condition was established, i.e., pressure = 5 MPa, temperature = 180°C, and the impregnation time = 30 min. The void contents of the composites were estimated using the ignition method and the tensile properties were measured. The results revealed that good impregnation of the matrix ionomer into the reinforcing agent can be achieved at 180°C. This was confirmed by low void content as compared with other test temperatures. Further clarification was through the tensile properties, which were higher than those at lower temperatures (120 and 150°C). The effect of fiber orientation was checked, and both 0 and 90° had identical strengths and moduli irrespective of the various fiber treatments. Apart from the void contents, the degree of impregnation was also checked based on the tensile strengths in 45, 25, and 60° fiber orientations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1395–1400, 2001
Preparation of aminopropyl polysiloxane‐based heat‐curable silicone rubber
Authors: Wu Yongzhong , Feng Shengyu , Bei Yiling , Liu Peng
Published: August 2002

By using polysiloxane containing aminopropyl groups as a base gum and polysiloxane containing epoxy groups as a crosslinker, we prepared a new type of addition‐curable silicone rubber and investigated in detail the effect of various factors on the silicone rubber. Better technical conditions were determined and the vulcanizates with fine mechanical properties were obtained. The tensile strength, tear strength, elongation at break, and hardness of the vulcanizates reach 8.1 MPa, 19.4 kN/m, 420%, and 64 ShA, respectively. To analyze the crosslinking statue, we measured their crosslinking density by toluene‐swelling methods. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2341–2346, 2001
Preparation and physical properties of konjac glucomannan–polyacrylamide blend films
Authors: Xiao Chaobo , Lu Yongshang , Zhang Lina
Published: August 2002

The blend films of konjac glucomannan (KGM) and polyacrylamide (PAAm) were prepared by using the solvent‐casting technique. Transparent blend films were obtained in all blending ratios. The physical properties of the films were investigated by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and by measurement of mechanical properties. The results indicated the occurrence of intra‐ and intermolecular interactions of the pure components, as well as the intermolecular interactions between KGM and PAAm through hydrogen bond formation. The thermal stability and mechanical properties of both tensile strength and elongation at break of the films were improved by blending KGM with PAAm. It was worth noting that the blend film had the greatest tensile strength when the KGM content in the blend films was around 30 wt %. Surface morphology of the films observed by SEM was consistent with the above‐noted results. Furthermore, the water absorbability of the blend films was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 882–888, 2001
Modification of aqueous polyurethanes via latex AB crosslinked polymers
Authors: Lee Jeong Sam , Kim Byung Kyu
Published: August 2002

A series of Latex AB crosslinked polymers have been synthesized from polyurethane (PU) (polymer A) and polystyrene (PS) (polymer B). The effect of PU/PS composition, crosslinking density in the PS domain, as well as in PU has been studied in terms of dispersion size, TEM morphology, mechanical, dynamic mechanical properties, in addition to swellability in water and toluene of the dispersion cast film. An inverted core (PS)‐shell (PU) morphology with very fine (tens of nanometers) dispersion was obtained, and the film properties were well controlled by the Latex composition and crosslinking density of both phases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1315–1322, 2001
Novel organic/inorganic nanocomposite of polyethylene. I. Preparation via in situ polymerization approach
Authors: Rong Junfeng , Li Hangquan , Jing Zhenhua , Hong Xiaoyu , Sheng Miao
Published: August 2002

A novel methodology for the preparation of polyethylene/palygorskite, “in situ coordinated polymerization,” was proposed. A Ziegler–Natta catalyst was first supported on the surface of nanoscale crystal fibers of palygorskite and subsequently used to initiate ethylene polymerization on the surface of the fibers. The palygorskite was encapsulated by polyethylene and became reinforcement fibers of the composite. The palygorskite fibers were heat‐treated to remove water, to ensure that the supported titanium species possessed proper activity for the polymerization of ethylene. The effect of the conditions of heat‐treating, titanium‐supporting, and other factors such as temperature and type and amount of the cocatalyst on the initiation activity of the palygorskite fibers were investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1829–1837, 2001
Investigation of the melting behavior and morphology development of polymer blends in the melting zone of twin‐screw extruders
Authors: Potente H. , Krawinkel S. , Bastian M. , Stephan M. , Pötschke P.
Published: August 2002

The melting behavior and the morphology development that runs parallel to it play central roles in the processing of polymer blends. We studied the impact of speed, melt throughput, continuous‐phase viscosity, screw configuration, and disperse‐phase content on the melting behavior and morphology development in the melting zone of a twin‐screw extruder. The polymer blend used incorporated polyamide‐6 (PA6) as its disperse phase and a high‐viscosity or low‐viscosity polypropylene as the matrix phase. The melting behavior of the polymer blend was investigated with press plates. A qualitative assessment was made of the processes, on basis of the optical impression gained from the transilluminated press plates. One key result was that the PA6 granules melted very rapidly in the polypropylene melt. We took samples over the length of the melting section to permit a quantitative assessment of the morphology. The results show a finely dispersed morphology already at the start of the melting section. This did not undergo any essential change as the blend passed through the extruder, and only a limited correlation was evident with the process parameters. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1986–2002, 2001
Phosphate‐containing flame‐retardant polymers with good compatibility to polypropylene. II. Effect of the flame‐retardant polymers on polypropylene
Authors: Chiang Wen‐Yen , Hu Howard C.‐H.
Published: August 2002

Two kinds of flame‐retardant polymers prepared from the phosphorylation of poly(vinyl acetate) were employed to reduce the flammability of polypropylene (PP). The two flame‐retardant polymers had very different effects because of the differences in their chemical structure. Effects on flame retardancy, thermal properties, mechanical properties, and phase morphology were investigated. Under a certain molecular design, the flame‐retardant polymers were able to offer good flame retardancy, good mechanical properties, and good PP matrix compatibility. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2399–2403, 2001
The tensile and compressive deformation of polymer and carbon fibers
Authors: Northolt M. G. , Baltussen J. J. M.
Published: August 2002

An outline of the continuous chain model for the description of the tensile and compressive deformation of polymer fibers below the glass transition temperature is presented. The basic mechanism is the contraction of the chain orientation distribution as a result of elastic, plastic, and viscoelastic shear deformation. The deformation of the fiber is calculated for finite strains and arbitrary values of the orientation parameter. The model explains the yield and the compressive strength of polymer fibers. The tensile curve, including yielding, is described in terms of the modulus for shear between the chains, the chain modulus, the chain orientation distribution, and a yield parameter. The response to complex time‐dependent loading schemes can be calculated by introduction of the Eyring reduced time model. The elastic tensile deformation of carbon fibers is described in terms of the classical series aggregate model. It is shown that the modulus for shear between the graphitic planes and the orientation distribution of these planes govern the tensile and compressive properties of carbon fibers. The high values of the shear modulus are attributed to some covalent bonding between the graphitic planes. A survey of the various models for the strength of polymer fibers is presented and a new model is discussed, which explains the failure envelope of polymer fibers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 508–538, 2002
Dispersion polymerization of acrylamide in aqueous solution of ammonium sulfate: Synthesis and characterization
Authors: Cho M. S. , Yoon K. J. , Song B. K.
Published: August 2002

Dispersion polymerization of acrylamide (PAM) has been successfully carried out in aqueous ammonium sulfate media by using poly(acryloyloxyethyl trimethylammonium chloride) (PAOTAC) as the polymeric stabilizer and 2,2′‐azobis(2‐methyl propionamidine) dihydrochloride (AIBA) as the initiator. The polymerization behaviors with varying concentrations of acrylamide, PAOTAC, AIBA, and ammonium sulfate were investigated. The reaction conditions for stable dispersion were concentrations of 5–10% for acrylamide, 0.6–1.8% for the stabilizer, 0.92–1.84 × 10−4 mol/L for the initiator, and 24–30% for the salt. The resulting conversion–time curves were S‐shaped, as is typically observed in polymerization. Polydisperse spherical particles were formed in the system. An image analyzer photographed the size of the dispersed particles and their distribution was measured. The mechanism and kinetics for the dispersion polymerization were discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1397–1405, 2002
Retinoic acid administration is associated with changes in the extracellular matrix and cardiac mesenchyme within the endocardial cushion
Authors: Yan Min , Sinning Allan R.
Published: August 2002

Retinoic acid has been associated with a number of cardiac defects, some of which seem to be related to changes in the endocardial cushions. Studies in mice and older chick embryos have suggested that these defects may be associated with a decrease in mesenchymal cell formation within the cushion. In a previous report we showed that retinoic acid lowered the number of mesenchymal cells in a culture bioassay of mesenchyme formation and that this response was due to retinoic acid modifying the production of particulate matrix from the myocardium. In this study, we have extended these observations to the embryo by implanting a retinoic acid coated bead into the embryo and examined the effect on cardiac mesenchyme formation and in the production of the particulate matrix. In all cases the addition of retinoic acid resulted in a decrease in the number of mesenchymal cells invading the endocardial cushions. In addition retinoic acid increased the production of hLAMP‐1 and fibronectin but not transferrin, confirming our earlier report. Finally, we measured the volume of the cushion and calculated the cell density of both the inferior and superior cushions. The results suggest that the superior cushion is more sensitive to retinoic acid treatment than the inferior cushion. Collectively, these results support our earlier work that suggests that the mechanism of retinoic acid cardiac abnormalities involves a disruption in the production of particulate matrix from the myocardium and a subsequent decrease in cardiac mesenchyme cells that results in a malformed cardiac cushions. Anat Rec 263:53–61, 2001. © 2001 Wiley‐Liss, Inc.
Communicating science: From the laboratory bench to the breakfast table
Authors: Hendrix Mary J.C. , Campbell Paulette W.
Published: August 2002

If we are to maintain public appreciation and support for our scientific enterprise, we need to pay more attention to translating the benefits and grandeur of science into the language of broader society. Both educators and journalists have a role to play in communicating the achievements of science, but scientists must recognize that we have a responsibility to increase the availability and salience of science to the public.
Changes of protein tyrosine phosphorylation in third instar larval integument of the Mediterranean fruit fly, Ceratitis capitata
Authors: Zervas Christos G. , Katsoris Panagiotis G. , Marmaras Vassilis J.
Published: August 2002

Developmental analysis of the tyrosine protein phosphorylation levels in larval integument and partial characterization of the endogenous protein tyrosine kinase activity (PTK) in Ceratitis capitata are described in this study. Larval integument contains high levels of PTK activity at the early stages of the third instar, which progressively declines to low levels in the white pupal stage. An integumental 90‐kDa polypeptide was identified to have prominent endogenous PTK activity and follow a similar developmental pattern. The major integumental phosphotyrosine‐containing polypeptides have apparent molecular weights of 30, 41, 44, 46, and 54 kDa, respectively. Polypeptides with molecular weights of 62 and 73 kDa were identified as Ser/Thr‐containing phosphoproteins and were shown to exhibit high levels of phosphorylation at the middle stage of larval development. These differences are likely to be due to the higher activation state of the protein tyrosine kinase(s) at the early stages of larval development. Arch. Insect Biochem. Physiol. 50:9–20, 2002. © 2002 Wiley‐Liss, Inc.
Stimulation of trehalose efflux from cockroach (Periplaneta americana) fat body by hypertrehalosemic hormone is dependent on protein kinase C and calmodulin
Authors: Garcha D. Sun, K. , Steele J.E.
Published: August 2002

Protein kinase C and calmodulin play key roles in cockroach fat body during activation of phosphorylase and trehalose efflux by HTH‐II. The data support the view that an increase in cytosolic Ca2+ is prerequisite for enhanced activity of protein kinase C and calmodulin. Chelation of Ca2+i with BAPTA blocks HTH‐II‐induced trehalose efflux from the fat body whereas thapsigargin, which raises [Ca2+]i to the same level as HTH‐II, produces only a small, yet significant increase in trehalose efflux. Sphingosine, an inhibitor of protein kinase C, inhibits HTH‐II‐induced trehalose efflux in a concentration‐dependent manner. Trehalose efflux is not activated by the protein kinase C activators OAG or PMA alone but in the presence of thapsigargin both agents increase trehalose efflux to a level comparable to that obtained with HTH‐II. Thapsigargin has only a moderate activating effect on phosphorylase but in combination with OAG produces an activation indistinguishable from that provoked by HTH‐II. Each of the structurally different calmodulin inhibitors, trifluoperazine, W‐7, and calmidazolium, blocks completely the action of HTH‐II on trehalose efflux, thus confirming the importance of calmodulin in HTH‐II initiated trehalose efflux. Arch. Insect Biochem. Physiol. 50:41–51, 2002. © 2002 Wiley‐Liss, Inc.
Significance of absorption, oxidation, and binding to toxicity of four ecdysone agonists in multi‐resistant cotton leafworm
Authors: Smagghe Guy , Carton Bert , Decombel Luc , Tirry Luc
Published: August 2002

Treatment of last‐instar larvae of multi‐resistant cotton leafworm Spodoptera littoralis with four dibenzoylhydrazines, methoxyfenozide (RH‐2485), tebufenozide (RH‐5992), halofenozide (RH‐0345), and RH‐5849, resulted in premature molting leading to death. Methoxyfenozide was the most toxic followed by tebufenozide, halofenozide, and RH‐5849. To explain differences in toxicity, especially between multi‐resistant and laboratory strains, absorption in the body tissues and oxidative metabolism were tested with 14C‐labeled ecdysone agonist and a Lineweaver‐Burk assay, respectively. Then to address different compound potencies in multi‐resistant strains, the potency of the four ecdysone agonists was measured based on their ability to mimic the natural insect molting hormone, 20‐hydroxyecdysone (20E) by inducing evagination in isolated imaginal wing discs. Using monoclonal antibody 9B9, the presence of ecdysteroid receptors in imaginal discs in vitro was confirmed. In parallel, Scatchard plot analysis with whole imaginal wing discs cultured with different concentrations of 3H‐labeled ponasterone A indicated no significant difference in affinity and in number of target sites for binding between multi‐resistant and susceptible laboratory strains. The four compounds tested caused the effect as agonists of 20E in vitro, and typically the order of their toxicities (LC50s) corresponded with that for evagination‐induction with whole imaginal discs. Arch. Insect Biochem. Physiol. 46:127–139, 2001. © 2001 Wiley‐Liss, Inc.
Assessment of the gene expression profile of differentiated and dedifferentiated human fetal chondrocytes by microarray analysis
Authors: Stokes David G. , Liu Gang , Coimbra Ibsen B. , Piera‐Velazquez Sonsoles , Crowl Robert M. , Jiménez Sergio A.
Published: August 2002

Objective

To study the changes in patterns of gene expression exhibited by human chondrocytes as they dedifferentiate into fibroblastic cells in culture in order to better understand the mechanisms that control this process and its relationship to the phenotypic changes that occur in chondrocytes during the development of osteoarthritis (OA).

Methods

Human fetal epiphyseal chondrocytes (HFCs) were cultured either on poly‐(2‐hydroxyethyl methacrylate)–coated plates (differentiated HFC cultures) or in plastic tissue culture flasks as monolayers (dedifferentiated HFC cultures). Following 11 days of culture under either condition, poly(A+) RNA was isolated from the two cell populations and subjected to a gene expression analysis using a microarray containing ∼5,000 known human genes and ∼3,000 expressed sequence tags (ESTs).

Results

A ≥2‐fold difference in the expression of 62 known genes and 6 ESTs was observed between the two cell types. The differences in expression of several of the genes detected by the microarray hybridization were confirmed by Northern analyses. Two transcription factor genes, TWIST and HIF‐1α, and a cellular adhesion protein gene, cadherin 11, were markedly regulated in response to differentiation and dedifferentiation. Expression of these genes was also detected in adult normal and OA cartilage and chondrocytes. Analysis of the gene expression profile of HFCs revealed a complex pattern of gene expression, including many genes not yet reported to be expressed by chondrocytes.

Conclusion

Chondrocytes in monolayer become dedifferentiated, acquiring a fibroblast‐like appearance and changing their pattern of gene expression from one of expression of chondrocyte‐specific genes to one that resembles a fibroblastic or chondroprogenitor‐like pattern. Changes in gene expression associated with the process of dedifferentiation of HFCs in vitro were observed in a wide variety of genes, including genes encoding extracellular matrix proteins, transcription factors, and growth factors. At least 3 of the genes that were regulated in response to dedifferentiation were also found to be expressed in adult normal and OA articular cartilage and chondrocytes.