bluuebunny/crossref_metadata_2025 huggingface dataset:
The Redox Regulation of LMW‐PTP During Cell Proliferation or Growth Inhibition
Authors: Chiarugi Paola
Published: August 2002

Summary Low‐molecular‐weight protein tyrosine phosphatase (LMW‐PTP) is an enzyme involved in platelet derived growth factor (PDGF)‐induced mitogenesis and cytoskeleton rearrangement, because it is able to bind and dephosphorylate the activated receptor. LMW‐PTP contains two cysteines located in position 12 and 17, both inside the catalytic pocket: this is a unique feature of LMW‐PTP among all protein tyrosine phosphatases. LMW‐PTP is oxidized and inactivated both in vitro and in vivo by exogenous oxidative stress and by endogenously generated oxidative burst produced during PDGF signaling, and recovers its activity within 40 min. The reversibility of in vivo LMW‐PTP oxidation is glutathione dependent. The additional catalytic pocket cysteine, in position 17, retains an intriguing and peculiar role in the formation of a S‐S intramolecular bond, which protects the catalytic Cys12 from further and irreversible oxidation. The presence of an additional cysteine near the catalytic one, confers to LMW‐PTP the ability to rapidly recover its activity and finely regulate PDGF receptor activation during both extracellularly and intracellularly generated oxidative stress. In addition, redox up‐regulation of LMW‐PTP is involved in intracellular delivery of antiproliferative signals, as the arrest of growth induced by cell confluence and differentiation are associated with a decrease in the steadystate levels of intracellular ROS. The studies of the redox state of LMW‐PTP in contact‐inhibited cells and in mature myoblasts demonstrate that the protein is reduced and activated in both these conditions, thus leading to the hypothesis that LMW‐PTP is a modulator of growth inhibition.
Mesomorphic phthalocyanines, tetraazaporphyrins, porphyrins and triphenylenes as charge-transporting materials
Authors: EICHHORN H.
Published: August 2002

The columnar mesomorphism of triphenylene-, phthalocyanine-, tetraazaporphyrin- and porphyrin-based compounds is briefly reviewed and the potential use of this particular supramolecular structure for charge-conducting devices is discussed. Suitably substituted triphenylenes exhibit ideal material properties for photoconducting devices, and well-aligned layers have been shown to give a very high charge carrier mobility of 0.1 × 10-4 m 2 V -1 s -1 (time-of-flight measurements). From a molecular point of view, porphyrin systems should be superior to triphenylenes, but the properties of their mesophases do not support the advantageous homeotropic alignment of the columnar stacks. However, pulse radiolysis time-resolved microwave conductivity measurements revealed the highest charge carrier mobility value of 0.28 × 10-4 m 2 V -1 s -1 for mesomorphic phthalocyanines.
Arsenic trioxide‐ and idarubicin‐induced remissions in relapsed acute promyelocytic leukaemia: Clinicopathological and molecular features of a pilot study
Authors: Kwong Y.L. , Au W.Y. , Chim C.S. , Pang A. , Suen C. , Liang R.
Published: August 2002

Arsenic trioxide (As2O3) effectively induces remissions in relapsed acute promyelocytic leukaemia (APL), but the safety of its long‐term administration is unknown. The anthracycline idarubicin is highly active alone or in combination chemotherapy for the treatment of APL. To minimize arsenic exposure and based on the high sensitivity of APL cells to anthracyclines, we conducted a prospective study to evaluate induction with As2O3 followed by consolidation with idarubicin in the treatment of APL in relapse. Eight patients were treated with As2O3 at a daily dose of 10 mg until remission, followed by three monthly courses of idarubicin, at 6 mg/m2/day for 5 days in the first course and 6 mg/m2/day for 2 days in the subsequent two courses. All patients achieved morphological but not molecular remission after As2O3 treatment. During As2O3 therapy, an increase in white cell count peaking at a median of 17 days occurred in all the cases. Serial flow cytometric analysis of apoptosis, with mitochondrial APO2.7 antigen expression and the sub‐G1 cell fraction on DNA histogram as markers, showed induction of apoptosis of APL cells in vivo. With both qualitative and real‐time quantitative polymerase chain reaction, all patients were shown to attain molecular remission after subsequent idarubicin treatment. With a median follow up of 13 months, seven of eight patients have remained in complete clinical remission, with six patients in molecular remission as well. One patient who was in third remission became PCR‐positive after being transiently negative. One patient died from an intracranial extramedullary relapse after achieving marrow molecular remission. We conclude that As2O3 induction followed by idarubicin consolidation is an effective therapy for APL in relapse. This regimen avoids the possible long‐term toxicities of As2O3 and mutagenicity of combination chemotherapy, a strategy that might be suitable for this potentially curable leukaemia. Am. J. Hematol. 66:274–279, 2001. © 2001 Wiley‐Liss, Inc.
Thalidomide‐associated hepatitis: A case report
Authors: Fowler Robert , Imrie Kevin
Published: August 2002

We report a case of hepatitis in a 58‐year‐old woman being treated with thalidomide for end‐stage plasma cell leukemia. The patient had a medical history including chronic stable hepatitis C infection. At diagnosis there was a severe anemia, thrombocytopenia, hypercalcemia, IgG paraproteinemia, peripheral blood myeloma cells, and a marrow plasmacytosis with lytic bony lesion. The disease was refractory to standard chemotherapy, and she was treated with oral thalidomide. Within 1 week she became jaundiced and developed a marked transaminitis. This promptly resolved upon cessation of thalidomide alone. Thalidomide has recently enjoyed renewed interest as a treatment in many disorders, including plasma cell leukemia. To our knowledge, this is the first reported case of thalidomide‐associated hepatotoxicity. Although the mechanism of its actions on the liver are uncertain, it is possible that thalidomide acts as a direct hepatotoxin or as an immuno‐modulator, altering the activity of chronic viral hepatitis. We present this case to increase awareness of a new potential side effect of thalidomide as its clinical indications expand. Am. J. Hematol. 66:300–302, 2001. © 2001 Wiley‐Liss, Inc.
Successful treatment of severe aplastic anemia associated with human parvovirus B19 and Epstein‐Barr virus in a healthy subject with allo‐BMT
Authors: Kaptan Kürşad , Beyan Cengiz , Ural Ali Uğur , Üstün Celalettin , Çetin Türker , Avcu Ferit , Kubar Ayhan , Alış Metin , Yalçın Atilla
Published: August 2002

Several reports have noted pancytopenia associated with Human parvovirus B19 (PVB19) or Ebstein‐Barr virus (EBV) infections in patients who have no history of immunodeficiency. To our knowledge, we report the first case of severe aplastic anemia associated with both EBV and PVB19 infections in a previously healthy 22‐year‐old man. He was admitted to our hematology service due to anemia and thrombocytopenia. He had no symptoms or signs of infections of these viruses. His bone marrow biopsy revealed a hypocellular marrow. Specific IgM and IgG antibodies to EBV and PVB19 were elevated. EBV and PVB19 virus genomes were detected by PCR in the bone marrow nucleated cells and the peripheral blood lymphocytes. Two months after treatment with prednisone, acyclovir, and intravenous immune globulin (IVIg), the genomes of both these viruses disappeared. However, his transfusion requirement for platelet suspensions and packed red blood cells persisted. The patient underwent allogeneic bone marrow transplant (allo‐BMT) and has had an enduring complete hematological response for 8 months. Am. J. Hematol. 67:252–255, 2001. © 2001 Wiley‐Liss, Inc.
Osteopathia striata cranial sclerosis: Non‐random X‐inactivation suggestive of X‐linked dominant inheritance
Authors: Viot Géraldine , Lacombe Didier , David Albert , Mathieu Michèle , de Broca Alain , Faivre Laurence , Gigarel Nadine , Munnich Arnold , Lyonnet Stanislas , Le Merrer Martine , Cormier‐Daire Valérie
Published: August 2002

Osteopathia striata with cranial sclerosis (OS‐CS) is a rare syndrome comprising macrocephaly, minor anomalies, conductive hearing loss, and mild mental retardation. The diagnosis is based on radiological findings, including cranial sclerosis and longitudinal striations of metaphyses of long bones. Here we report on 10 new cases of OS‐CS, including two sporadic cases and three families, with an excess of affected females (9F/1M). Phenotypic variability was observed in our patients as well as several unusual findings. Hirschsprung disease, Pierre Robin sequence, coronal craniostenosis, and laryngotracheomalacia were associated with a poor prognosis. The X‐inactivation pattern of peripheral blood lymphocytes in a mildly affected mother and her severely affected boy demonstrated a non‐random X‐inactivation in the mother. This finding, in combination with a sex ratio in favor of females and an increased morbidity and mortality in males, is highly suggestive of X‐linked dominant inheritance. © 2001 Wiley‐Liss, Inc.
Sotos syndrome associated with a de novo balanced reciprocal translocation t(5;8)(q35;q24.1)
Authors: Imaizumi Kiyoshi , Kimura Junko , Matsuo Mari , Kurosawa Kenji , Masuno Mitsuo , Niikawa Norio , Kuroki Yoshikazu
Published: August 2002

We describe a de novo balanced reciprocal translocation between the long arms of chromosomes 5 and 8 [46,XX,t(5;8)(q35;q24.1)] in a 15‐month‐old girl with a typical Sotos syndrome phenotype. Involvement of the 5q35 region was previously reported (Maroun et al. [1994: Am J Med Genet 50:291–293]) as one of translocation breakpoints in the present patient. We suggest that the gene responsible for Sotos syndrome is located to a distal long‐arm region of chromosome 5. © 2001 Wiley‐Liss, Inc.
Correlation between serotonin uptake in human blood platelets with the 44‐bp polymorphism and the 17‐bp variable number of tandem repeat of the serotonin transporter
Authors: Kaiser Rolf , Müller‐Oerlinghausen Bruno , Filler Diana , Tremblay Pierre‐Benoit , Berghöfer Anne , Roots Ivar , Brockmöller Jürgen
Published: August 2002

Dysfunctions of the central serotonin (5‐hydroxytryptamine, 5‐HT) system seem to be associated with psychiatric disorders such as schizophrenia or depression. Previous studies suggested that a 44‐bp insertion/deletion polymorphism of the 5‐HT transporter (5‐HTT) promoter region might influence the transcriptional activity of the 5‐HTT gene, and the insertion variant resulted in increased 5‐HTT expression and 5‐HT uptake. Moreover, a 17‐bp variable number of tandem repeat (VNTR) polymorphism of the second intron may act as a transcriptional regulator with allele dependent differential enhancer‐like properties. Since the 5‐HTT of human platelets shares many properties with the transporter of neural tissue, platelets are widely used as a surrogate tissue source, possibly reflecting central 5‐HT metabolism. Therefore, we investigated the impact of the 44‐bp polymorphism and the 17‐bp VNTR for 5‐HT uptake in platelets of 50 male subjects. We found no significant effect of the 44‐bp polymorphism and of the 17‐bp VNTR on maximum rate (Vmax) of 5‐HT uptake. However, individuals homozygous for the 5‐HTT intron 2 allele with 12 repeats (STin2.12) of the 17‐bp VNTR appeared to have lower affinity of 5‐HT uptake than individuals heterozygous for the STin2.10/STin2.9 allele. This was also observed for the combined analysis of both polymorphisms. In conclusion, we found no association between the different genotypes of the 44‐bp polymorphism and the 17‐bp VNTR and maximum rate of 5‐HT uptake into platelets. © 2002 Wiley‐Liss, Inc.
The norepinephrine transporter gene and attention‐deficit hyperactivity disorder
Authors: Barr Cathy L. , Kroft Jamie , Feng Yu , Wigg Karen , Roberts Wendy , Malone Molly , Ickowicz Abel , Schachar Russell , Tannock Rosemary , Kennedy James L.
Published: August 2002

The adrenergic system plays a known role in attentional systems and a suspected causal role in attention‐deficit hyperactivity disorder (ADHD), based on evidence from pharmacological interventions and animal models. The efficacy of the highly selective noradrenergic reuptake inhibitor, tomoxetine, in treating ADHD symptoms supports the system's role in ADHD and points to the norephinephrine transporter as a candidate gene. This study tested the gene for the norepinephrine transporter (NET1) as a susceptibility factor in ADHD using three polymorphisms located in exon 9, intron 9, and intron 13. We examined the inheritance of these polymorphisms in a sample of 122 families with a total of 155 children with ADHD identified through an ADHD proband. Use of the transmission disequilibrium test failed to show significant evidence for biased transmission of any of the alleles or the haplotypes of these polymorphisms. We further investigated this gene by screening the probands for five known amino acid variants to determine if they contributed to the ADHD phenotype but observed only one (Thr99Ile) in our sample. Since the frequency of this variant (1.8%) was similar to that previously reported in a control sample (2.2%), it is unlikely that this variant is related to the ADHD phenotype. Our results do not support the NET1 gene as a major genetic susceptibility factor in ADHD. © 2002 Wiley‐Liss, Inc.
Absence of thumbs, a/hypoplasia of radius, hypoplasia of ulnae, retarded bone age, short stature, microcephaly, hypoplastic genitalia, and mental retardation
Authors: Wieczorek Dagmar , Köster Bernhard , Gillessen‐Kaesbach Gabriele
Published: August 2002

The previously unreported combination of bilateral absence of thumbs, aplasia of ulna at one and hypoplasia of ulna on the other side, retarded bone age, short stature, microcephaly, micropenis, cryptorchidism, and mental retardation is described in a 5‐year‐old boy. Having excluded major differential diagnoses, e.g. Fanconi anemia, RAPADILINO syndrome and VACTERL association, we hypothesize that this boy represents a new multiple congenital anomaly/mental retardation (MCA/MR) syndrome. © 2002 Wiley‐Liss, Inc.
Determining isotopic life history trajectories using bone density fractionation and stable isotope measurements: A new approach
Authors: Bell Lynne S. , Cox Glenda , Sealy Judith
Published: August 2002

A number of recent studies have attempted to trace diet at different stages of an individual's life by comparing isotope ratios of bone from different gross anatomical sites within the skeleton. In this study we develop this approach further by separating bone of differing mineral densities within one skeletal element, where each density fraction represents a different period of time. Isotope ratios are measured for these fractions. Each density fraction represents a period of bone formation and maturation, where younger (more recently formed) bone is less well‐mineralized and therefore less dense than relatively older packets of bone. In an adult, bone is therefore able to partition approximately the last 15 years of life. Bone fractions were recovered by stepped ultracentrifugation in a series of organic solvents of increasing density, and then collagen was recovered by decalcification in dilute acid, and stable carbon isotope ratios (13C/12C) were measured. Bone density microstructure was checked for bacterial remodelling using backscattered electron imaging in a scanning electron microscope. Our results indicate that the bone density fractionation method is applicable to archaeological material, here extending to a maximum of 5,000 years BP, and that collagen can successfully be extracted from such fractions. The carbon isotope values for bone fractions of different densities patterned out as expected in one modern control bone and in specimens from five archaeological human skeletons, including three precolonial hunter‐gatherers and two 18th/19th century individuals. The latter two are known (from previous assessments) to have undergone marked changes in diet during their lifetimes. Postmortem alteration was evident in some of the specimens examined. The bone density fractionation approach has allowed greater resolution of diet than has hitherto been possible and has provided access to the elusive last years and months of an individual's life. Am J Phys Anthropol 116:66–79, 2001. © 2001 Wiley‐Liss, Inc.
Perikymata spacing and distribution on hominid anterior teeth
Authors: Dean M.C. , Reid D.J.
Published: August 2002

We documented the spacing and distribution of perikymata on the buccal enamel surface of fossil hominin anterior teeth with reference to a sample of modern human and modern great ape teeth. A sample of 27 anterior teeth attributed to Australopithecus (5 to A. afarensis, 22 to A. africanus) and of 33 attributed to Paranthropus (6 to P. boisei, and 27 to P. robustus) were replicated and sputter‐coated with gold to enable reflected light microscopy of their surface topography. Anterior teeth were then divided into 10 equal divisions of buccal crown height. The total perikymata count in each division of crown height was recorded using a binocular microscope fitted with a vernier micrometer eyepiece. Then the mean number of perikymata per millimeter was calculated for each division. Similar comparative data for a modern sample of 115 unworn human anterior teeth and 30 African great ape anterior teeth were collected from ground sections. Perikymata counts in each taxon (together with either known or presumed periodicities of perikymata) were then used to estimate enamel formation times in each division of crown height, for all anterior tooth types combined. The distributions of these estimates of time taken to form each division of crown height follow the same trends as the actual perikymata counts and differ between taxa in the same basic way. The distinction between modern African great apes and fossil hominins is particularly clear. Finally, we calculated crown formation times for each anterior tooth type by summing cuspal and lateral enamel formation times. Estimates of average crown formation times in australopiths are shorter than those calculated for both modern human and African great ape anterior teeth. The data presented here provide a better basis for exploring differences in perikymata spacing and distribution among fossil hominins, and provide the first opportunity to describe four specimens attributed to Homo in this context. Preliminary data indicate that differences may exist among the species attributed to early Homo, especially between Homo ergaster and Homo rudolfensis on the one hand, and Homo habilis sensu strico on the other. Am J Phys Anthropol 116:209–215, 2001. © 2001 Wiley‐Liss, Inc.
Articular area responses to mechanical loading: effects of exercise, age, and skeletal location
Authors: Lieberman Daniel E. , Devlin Maureen J. , Pearson Osbjorn M.
Published: August 2002

How reliable are reconstructions of body mass and joint function based on articular surface areas? While the dynamic relationship between mechanical loading and cross‐sectional geometry in long bones is well‐established, the effect of loading on the subchondral articular surface area of epiphyses (hereafter, articular surface area, or ASA) has not been experimentally tested. The degree to which ASA can change in size and shape is important, because articular dimensions are frequently used to estimate body mass and positional behavior in fossil species. This study tests the hypothesis that mechanical loading influences ASA by comparing epiphyses of exercised and sedentary sheep from three age categories: juvenile, subadult, and adult (n = 44). ASA was measured on latex molds of subchondral articular surfaces of 10 epiphyses from each sheep. Areas were standardized by body mass, and compared to diaphyseal cross‐sectional geometrical data. Nonparametric statistical comparisons of exercised and control individuals found no increases in ASA in response to mechanical loading in any age group. In contrast, significant differences in diaphyseal cross‐sectional geometry were detected between exercised and control groups, but mostly in juveniles. The conservatism of ASA supports the hypothesis that ASA is ontogenetically constrained, and related to locomotor behavior at the species level and to body mass at the individual level, while variations in diaphyseal cross‐sectional geometry are more appropriate proxies for individual variations in activity level. Am J Phys Anthropol 116:266–277, 2001. © 2001 Wiley‐Liss, Inc.
Late‐onset frontotemporal dementia with a novel exon 1 (Arg5His) tau gene mutation
Authors: Hayashi Shintaro , Toyoshima Yasuko , Hasegawa Masato , Umeda Yuri , Wakabayashi Koichi , Tokiguchi Susumu , Iwatsubo Takeshi , Takahashi Hitoshi
Published: August 2002

We report a case of frontotemporal dementia and parkinsonism linked to chromosome 17 of 5 years' duration in an 81‐year‐old man whose brother had died at age 86 years with dementia. In this patient, we found frontal and temporal neuronal loss, glial‐predominant tau deposits, progressive supranuclear palsy‐like straight tubules, accumulation of 4‐repeat‐predominant Sarkosyl‐insoluble tau, and a novel exon 1 (Arg5His) tau gene mutation. This mutation decreased microtubule‐promoting capacity and increased fibrillation of tau in vitro. Thus, we consider that the Arg5His mutation is an authentic tau gene abnormality responsible for the patient's tau pathology and late‐onset dementia.
Relapsing–remitting autoimmune agrypnia
Authors: Batocchi Anna Paola , Della Marca Giacomo , Mirabella Massimiliano , Caggiula Marcella , Frisullo Giovanni , Mennuni Gioacchino Francesco , Tonali Pietro Attilio
Published: August 2002

A woman affected by multiple cranial nerve palsy developed several episodes of total insomnia and respiratory crises resulting from central breathing depression associated with dysautonomic symptoms. Oligoclonal IgG bands were present in her cerebrospinal fluid, and immunohistochemistry showed increased binding of serum and cerebrospinal fluid on γ‐aminobutyric acid‐ergic, synapse‐rich neuronal cells. Immunosuppressive treatment and plasma exchange were followed by clinical improvement, with restoration of sleep architecture and disappearance of respiratory crises, suggesting autoimmune pathogenesis of the syndrome.
Metabolism and organ distribution of arsenic in the freshwater fish Tilapia mossambica
Authors: Suhendrayatna  , Ohki Akira , Nakajima Tsunenori , Maeda Shigeru
Published: August 2002

Arsenic concentration and arsenic speciation in the liver, intestine, ovary, bone, brain, muscle, gill and eye of the freshwater fish Tilapia mossambica exposed to arsenic were investigated. The profile of arsenic distribution­in tissues of T. mossambica after exposure­to a medium containing arsenate was brain >­intestine  > ovary >   eyes >  muscle  > gill >  bone­> liver. The minimum content of arsenic is in liver tissue (2.5 μgAs g‐1 dry weight), whereas the maximum content is in brain tissue (61.8 μgAs­g‐1 dry weight). Arsenic accumulated in liver tissue was present as methylated arsenic species, and no inorganic arsenic species were found in liver tissue. A notable exception is in brain tissue. Most arsenic accumulated in brain tissue was inorganic arsenic species, and no methylated arsenic was found in brain tissue. In a dietary exposure treatment, the maximum arsenic accumulation in the tissue of T. mossambica fed with Neocaridina denticulata dosed with arsenic from a Chlorella vulgaris diet (via the food chain) is in the ovary (7.4 μgAs g‐1 dry weight), followed by gill, liver, muscle, bone, brain, eyes and intestine. Trace amounts of methylated arsenic were found in liver tissue in this treatment. Methylated arsenic in fish exposed via water was more evenly distributed in the organs compared with dietary exposure. Copyright © 2001 John Wiley & Sons, Ltd.
Speciation of arsenic in tube‐well water samples collected from West Bengal, India, by high‐performance liquid chromatography–inductively coupled plasma mass spectrometry
Authors: Shraim Amjad , Sekaran N. Chandra , Anuradha C. D. , Hirano Seishiro
Published: August 2002

The objective of this study was to report on the arsenic species present in tube‐well water samples collected from West Bengal, India, especially dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA), whose existence has not been reported in the literature. The water samples were collected from Jalangi Gram Panchayet (Murshidabad district, West Bengal, India). The samples were speciated for arsenic 11 days after collection. The samples were collected in duplicate. One part was acidified with nitric acid (final concentration 0.1%), whereas the other part was left unacidified. A quick and highly sensitive high‐performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS) technique was employed for the separation and detection of the arsenic species. Four arsenic species, namely arsenite [arsenic(III)], DMA, MMA and arsenate [arsenic(V)] were separated and analysed in less than 5 min. Total arsenic concentration was determined by flow injection (FI)‐ICPMS. Most of the samples were found to contain low concentrations of DMA and MMA (<2.1 ppb) and high concentrations of inorganic arsenic (>300 ppb). The existence of DMA and MMA in both acidified and unacidified water samples and in similar concentrations suggests that their presence is natural and not due to acidification. The detection limit of the four arsenic species was 0.06–0.10 ppb. The method was validated by spike recovery and analysis of two water standard reference materials (SRMs). The percentage recoveries of added spikes of all four species were 97–112%. The total arsenic concentration obtained by FI‐ICPMS and the sum of the four arsenic species obtained by HPLC–ICPMS for the two water SRMs agreed with the certified values. Moreover, the difference between the total arsenic and the sum of the four arsenic species for most of the water samples was less than 10%. Copyright © 2002 John Wiley & Sons, Ltd.
Butyltins and calmodulin: which interaction?
Authors: Cima Francesca , Dominici Debora , Mammi Stefano , Ballarin Loriano
Published: August 2002

Tributyltin (TBT), widely used as an antifouling biocide, is the most abundant pesticide in coastal environments. One of its main toxic effects is immunosuppression in both vertebrates and invertebrates. At sublethal doses of TBT, phagocytes lose their ability to move towards and ingest foreign particles. For short‐term cultures of haemocytes (60 min at 25 °C) of a marine invertebrate, the colonial ascidian Botryllus schlosseri, exposed to 10−5 M TBT, we previously reported dose‐ and time‐dependent impairment of yeast phagocytosis and changes in cell morphology related to cytoskeleton disorganization. These effects are Ca2+‐dependent, since inactivation of Ca2+‐adenosine triphosphatase and a sustained increase in cytosolic Ca2+ occurred. As TBT can antagonize the effect of chlorpromazine, a specific calmodulin (CaM) inhibitor, and the co‐presence of exogenous CaM and TBT in the incubation medium resulted in the absence of effects, we hypothesized an interaction between TBT and CaM. TBT may remove endogenous CaM from cell proteins, thus inactivating them and causing alteration of Ca2+ homeostasis. With the aim of confirming the hypothesis of a direct TBT–CaM interaction, we first studied the effects of co‐incubation of TBT with other exogenous proteins on restoring the ability of phagocyte morphology. Although bovine serum albumin was never able to restore cell morphology, the effect of human spectrin was similar to that described for CaM, suggesting a common non‐specific mechanism of action based on the interaction of TBT with exposed hydrophobic pouches. We also analysed the conformational changes of pure CaM (10−5 M) in the presence of various concentrations (10−4 to 10−3 M) of TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), by circular dichroism. Results indicate the dose‐ and time‐dependent interaction of TBT with CaM. This interaction is a non‐covalent interaction, probably hydrophobic in nature, between the aliphatic chains of TBT and the hydrophobic regions of Ca2+‐activated CaM. DBT and MBT turned out to be less active in inducing CaM conformational changes, without any significant differences between the two compounds. Copyright © 2002 John Wiley & Sons, Ltd.
Swelling kinetics of poly(N‐vinylimidazole‐co‐sodium styrenesulfonate) hydrogels
Authors: Valencia Joaquín , Piérola Inés F.
Published: August 2002

Hydrogels of N‐vinylimidazole and sodium styrenesulfonate were synthesized by radical crosslinking copolymerization. Transient swelling measurements in water, at room temperature, reveal an unusual behavior. For some gel compositions, the swelling time dependency is about a δ function: dry hydrogel pellets swell up readily to reach a high degree of swelling and, spontaneously, they deswell to collapse. Such peculiarity was interpreted in terms of several competing events in the swelling mechanism: water diffusion toward the gel, chain disentanglement, sodium–proton interchange through the gel–external bath boundary, approaching of chains to allow interaction of sulfonate groups with neighboring protonated imidazole moieties and diffusion of water outside the gel. The results of cyclic swelling–deswelling following abrupt changes of composition in the external bath, from water to sodium hydroxide solution, support that mechanism. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 191–200, 2002
Suppression of radiation‐induced oxidation of polymers by sputtered silicon oxide coating
Authors: Zheng W. , Kobayashi Y. , Hirata K. , Miura T. , Kobayashi T. , Iwaki M. , Oka T. , Hama Y.
Published: August 2002

Oxygen barrier coating on polymers was attempted to obtain polymeric composite materials with improved radiation resistance. Silicon oxide (SiO1.6) films ranging from 120 to 240 nm thick were formed on polypropylene (PP) and polyethylene (PE) by radio frequency (RF) magnetron sputtering. Oxygen permeability after SiO1.6 deposition was reduced significantly in all samples studied, indicating that silicon oxide is a useful gas barrier. The oxygen permeability coefficient of deposited films for PP was 1.7–2.2 × 10−14 cm3‐cm/cm2/s/cmHg and that for PE was 2.8–4.8 × 10−13 cm3‐cm/cm2/s/cmHg. We studied the effect of such films on the radiation resistance of polymers in the presence of oxygen by microscopic infrared (IR) absorption spectroscopy. Silicon oxide films 180 nm thick were deposited on the surfaces of PP and PE, and the formation of carbonyl groups after irradiation in air was measured as a function of depth from the surface. Results compared with those for uncoated PE and PP showed that the radiation‐induced polymer oxidation is dramatically suppressed by silicon oxide coating. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 186–190, 2002
Isothermal crystallization behavior and properties of polypropylene/EPR blends nucleated with sodium benzoate
Authors: Jang Gu‐Su , Jo Nam‐Ju , Cho Won‐Jei , Ha Chang‐Sik
Published: August 2002

The effect of sodium benzoate on the isothermal crystallization behavior of isotactic polypropylene (iPP)/ethylene–propylene rubber(EPR) blends was investigated using differential scanning calorimetry. Dynamic mechanical and physical properties of the iPP/EPR blends nucleated with sodium benzoate were also measured. It was found that the crystallization behavior and physical properties such as heat deflection temperature (HDT), flexural modulus, and impact strength were strongly affected by the competition between the nucleating effect of EPR attributed to its partial compatibility with iPP and the simple addition of the amorphous component, as well as the nucleating effect of sodium benzoate. High impact strength was achieved by addition of EPR and sodium benzoate to iPP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 201–211, 2002
Compatibilization of intumescent flame retardant/polypropylene composites based on α‐methacrylic acid grafted polypropylene
Authors: Ma Zhi‐Ling , Zhao Min , Hu Han‐Fang , Ding Hai‐Tao , Zhang Jie
Published: August 2002

A phosphoric acid–pentaerythritol–melamine copolymer was selected as an intumescent flame retardant (IFR). The influence of α‐methacrylic acid grafted polypropylene (PP‐g‐MAA) on the properties and compatibility of IFR/PP composites was studied. The results obtained from mechanical tests and scanning electron microscopy showed that PP‐g‐MAA was a true coupling agent for IFR/PP blends, but it did not change the necessary flame retardancy. The cocrystallization between bulk PP and PP segments of PP‐g‐MAA was proved by wide‐angle X‐ray diffraction analysis. A flow test showed that the flow behaviors of composites in the melt were those of a pseudoplastic liquid and it was very small for PP‐g‐MAA and affected the rheological behavior of the PP/IFR composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3128–3132, 2002; DOI 10.1002/app.10099
A novel visible light photo‐induced acid‐generation system
Authors: Huimin Wang , Yongcai Jiang , Qingshan Li , Xiaohong Zhang , Shikang Wu
Published: August 2002

A novel, visible light, photo‐induced acid‐generation system composed of four types of intramolecular charge transfer compound and substituted bis(trichloromethyl) triazine was studied in this work. The photo‐induced electron transfer process between electron donor and electron acceptor was studied by the methods of fluorescence quenching and the change of fluorescence intensity with the time of irradiation. In the acidity measurement, the chemical reaction of acid formation of the studied system can be observed clearly. The acid‐induced cross‐linking reaction of m‐cresol resin and 2,4,6‐tris‐[N,N‐di(methoxymethyl) amino] triazine (HMMM) has also been studied. A clear negative image can be obtained after irradiation and developing by solvent. The possible mechanism of reaction has been discussed before. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 909–915, 2002; DOI 10.1002/app.10103
Water‐soluble grafted polysaccharides containing sulfobetaine groups: Synthesis and characterization of graft copolymers of hydroxyethyl cellulose with 3‐dimethyl(methacryloyloxyethyl)ammonium propane sulfonate
Authors: Zhang Li‐Ming , Chen Li‐Qiong
Published: August 2002

New water‐soluble grafted polysaccharides containing sulfobetaine groups were synthesized by the grafting of the sulfobetaine‐type zwitterionic monomer 3‐dimethyl‐(methacryloyloxyethyl)ammonium propane sulfonate (DMAPS) onto hydroxyethyl cellulose (HEC) in the presence of a ceric ammonium nitrate (CAN)/ethylenediaminetetraacetic acid (EDTA) initiation system. The effects of the concentrations of CAN, EDTA, DMAPS, and HEC, as well as the polymerization time and temperature, on the grafting reactions were investigated in terms of the grafting percentage (%GP) and grafting conversion (%GC) of the monomer. The %GP and %GC increased and then decreased with increasing concentrations of CAN, EDTA, and HEC. The %GP and %GC increased with increasing DMAPS concentration up to a certain value, beyond which the %GP did not significantly increase and the %GC decreased. The appropriate polymerization time and temperature were favorable for the grafting reactions. With infrared, thermogravimetric analysis, and viscosity measurements, the resulting grafted polysaccharides were characterized. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2755–2761, 2002; DOI 10.1002/app.10191
Semifluorinated ABA triblock copolymers: Synthesis, characterization, and amphiphilic properties
Authors: Zhang Zhao Bin , Ying Sheng Kang , Hu Qing Hua , Xu Xu Dong
Published: August 2002

In this study a series of novel semifluorinated ABA triblock copolymers with different fluorinated segment lengths and different fluorocarbon side‐chain structures were synthesized via atom transfer radical polymerization (ATRP) and macroinitiator techniques. The macroinitiator, telechelic bromine terminated polystyrene, was obtained from bulk ATRP of styrene with α,α′‐dibromo‐p‐xylene as the initiator and cuprous bromide/α,α′‐bispyridine complex as the catalyst. The polymerization reactions of 2‐[(perfluorononenyl)oxy] ethyl methacrylate and ethylene glycol monomethacrylate monoperfluorooctanoate were initiated by the macroinitiator in the presence of additional catalyst. The characterization of the block copolymers was performed by gel permeation chromatography, 1H‐NMR spectroscopy, and differential scanning calorimetry. The surface activities of the block copolymers in toluene were investigated with the Wilhelmy plate method. The solid surface energy of the block copolymers was determined by measurement of the contact angles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2625–2633, 2002
Investigations of surface degradation of high‐density polyethylene materials resulting from tracking, using physicochemical analysis
Authors: Sarathi R.
Published: August 2002

In the present work tracking phenomena were studied with high‐density polyethylene (HDPE) materials under dc voltage, with NH4Cl and acid rain as contaminants. It was determined that the tracking time of the material depends on the conductivity and flow rate of the contaminant. Furthermore, physicochemical analysis by wide‐angle X‐ray diffraction studies, differential scanning calorimetry, and luminescence spectroscopy was carried out, whereupon it was concluded that the tracking process is a surface‐degradation process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2843–2849, 2002; DOI 10.1002/app.10260
Studies of novel monomeric and polymeric azo disperse dyes
Authors: Maradiya Hari R. , Patel Vithal S.
Published: August 2002

A series of polymeric dyes were synthesized by free‐radical addition polymerization of monomeric dyes that were derived from diazotized 2‐amino‐3,5‐bis‐(ethoxycarbonyl)‐4‐methylthiophene by coupling with various N‐arylmaleimides. All the polymeric dyes were characterized by elemental analysis, IR and visible spectroscopy, viscometry, and TGA. Color and dyeability of the polymeric dyes are discussed by comparing them with those of the corresponding monomeric dyes. All the dyes have been found to give various color shades with good to very good depth and levelness on the fiber. The dyeing of the monomeric dyes shows good fastness to light and very good to excellent fastness to washing, perspiration, sublimation, and solvents. The corresponding polymeric dyes show excellent fastness properties. The percentage dyebath exhaustion and fixation on the fiber have been found to be good to very good (60–90%). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1380–1389, 2002; DOI 10.1002/app.10276
Synthesis and properties of PVC‐bound N,N‐dialkylaminopyridine
Authors: Wei Rongbao , Liang Ya , Chen Suzhan , Jia Chenxi , Li Fan , Zhang Tao
Published: August 2002

A linear poly(vinyl chloride) (PVC)‐supported dialkylaminopyridine was prepared through PVC treated with N‐methylaminopyridine and NaH in tetrahydrofuran. The properties of this PVC‐bound catalyst were examined by acetylation of linalool and 5‐FU. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1067–1069, 2002; DOI 10.1002/app.10391
Functionalization of crosslinked polyacrylamide through γ‐radiation‐induced grafting of 4‐vinylpyridine
Authors: Pande C. S. , Sharma Ajay
Published: August 2002

Crosslinked polyacrylamide beads were irradiated in air with a Co60 γ‐radiation source. The preirradiated beads were graft‐copolymerized through heating with 4‐vinylpyridine in the presence of benzoyl peroxide. Grafting was studied as a function of various reaction parameters and was determined from the increase in the weight of the original polymer and the estimation of pyridine pendants in the homopolymer‐free graft copolymer. Although making the polymer basic in character, this modification retained the hydrophilic nature of polyacrylamide. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2613–2620, 2002
Studies on isotactic poly(phenyl glycidyl ether)‐modified epoxy resins. II. Toughening of epoxy resins
Authors: Zhang Zheng , Yu Yunzhao
Published: August 2002

A semicrystalline polymer, isotactic poly(phenyl glycidyl ether) (i‐PPGE) was used as a modifier for epoxy resin; 1,8‐Diamino‐p‐methane (MNDA) and 4,4′‐Diamino diphenyl sulfone (DDS) were used as curing agents. In the MNDA‐cured resins, the dispersed phase were spherical particles with diameters in the range of 0.5–1.0 μm when the resin was blended with 5 phr i‐PPGE. In the DDS‐cured resins, the particle size distribution of the dispersed phase was much wider. The difference was traced back to the reactivity of the curing agent and the different regimes used for curing. Through dynamic mechanical analysis, it was found that in the MNDA‐cured systems, i‐PPGE had a lower crystallinity than in the DDS‐cured system. In spite of the remarkable difference in the morphology and microstructure of the modified resins cured with these two curing agents, the toughening effects of i‐PPGE were similar for these resins. The critical stress intensity factor (KIC) was increased by 54% and 53%, respectively, for the resins cured by DDS and by MNDA, blending with 5 phr of the toughner. i‐PPGE was comparable with the classical toughners carboxyl‐terminated butadiene‐acrylonitrile copolymers in effectiveness of toughening the epoxy resin. An advantage of i‐PPGE was that the modulus and the glass‐transition temperature of the resin were less affected. However, this modifier caused the flexural strength to decrease somewhat. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1223–1232, 2002; DOI 10.1002/app.10445
Redox initiation of copolymerization of styrene with hydroxyl terminated polybutadiene using Ce(IV) as an oxidant
Authors: Bajpai Anjali , Simon Joshy
Published: August 2002

Radical polymerization of styrene (St) with hydroxyl‐terminated polybutadiene (HTPB) using Ce(IV) as an oxidant was carried out under nitrogen atmosphere. The formation of styrene–butadiene block copolymer was confirmed by 1H‐NMR and IR spectroscopy. The variation in reaction parameters affected the yield of the product. St homopolymer formation under the reaction conditions used is ruled out. Crosslinking of polybutadiene chains through the styryl radical on growing block copolymer chains is suggested from viscosity and swelling measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 244–256, 2002
Study of the epoxy system BADGE (n = 0)/1,2‐DCH/CaCO3 filler by DMA and DSC
Authors: Núñez Lisardo , Núñez M. R. , Villanueva M. , Castro A. , Rial B.
Published: August 2002

The influence of an inorganic filler, CaCO3, on the curing kinetics of an epoxy system composed of diglycidyl ether of bisphenol A [BADGE (n = 0)], 1,2‐diaminecyclohexane (1,2‐DCH), and CaCO3 filler was studied by DMA and DSC. Different contents of filler in the range from 10 to 30%, referred to the total weight of the mixture, were tried. It was found that maximum reproducibility of the results and better performance correspond to a filler content of 20%. As usual, the Tg's obtained by DMA and DSC are different at 10–20°C. The results obtained from this study were compared with those corresponding to the system BADGE (n = 0)/1,2‐DCH without filler; the Tg for this last system is higher than that for the system with filler incorporated, whereas E′ and Mc (molecular weight between repetition units) are lower for the system without filler. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 366–370, 2002
Effects of spin finish on fiber surface hardness: An investigation with atomic force microscopy and frictional measurements
Authors: Kamath Y. K. , Ruetsch S. B. , Petrovicova E. , Kintrup L. , Schwark H.‐J.
Published: August 2002

Spin finishes are applied to melt‐spun fibers to protect them from abrasion during processing. The principal component of the fiber finish is a lubricant, which generally is a random or block copolymer of ethylene oxide/propylene oxide. Although these polymers do not penetrate the fiber because of their high molecular weight, depending on the nature of the fiber polymer, they interact to cause changes in the hardness of the fiber surface. This happens to be the case with acidic polymer fibers such as nylon‐6 and polyester [poly(ethylene terephthalate], both of which are softened by the ethylene oxide/propylene oxide lubricant. We used atomic force microscopy with nanoindentation capability to study the effect of lubricants on the microhardness of nylon‐6 and poly(ethylene terephthalate) fiber surfaces. Softening of the fiber surface by plasticization generally results in an increase in fiber friction because of shear deformation at the interface. We made an effort to determine the friction of fibers against a hard stainless steel surface after coating them with the finish lubricant for different lengths of time. The relevance of these results to fiber processing is discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 394–414, 2002
Positron annihilation lifetime studies of gas sorption and desorption in polyethylene and poly[1‐(trimethylsilyl)‐1‐propyne]
Authors: Mohsen M. , Gomaa E. A. H. , Schut H. , Van Veen A.
Published: August 2002

The variation of free‐volume parameters (lifetime, intensity, and distribution) after sorption and desorption of CO2 and CH4 gases in the glassy polymer poly[1‐(trimethylsilyl)‐1‐propyne] (PTMSP) and in the rubbery high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) were determined by the PAL technique. Size distributions deduced from PAL measurements reveal the presence of large free‐volume holes in PTMSP with an average size of 0.725 nm3 and intensity of 22% in addition to a free‐volume hole size of 0.197 nm3 with an intensity of 11%. In polyethylene free‐volume hole sizes of 0.107 and 0.153 nm3 with intensities of 21% and 25% could be deduced for HDPE and LDPE, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 970–974, 2001
Preparation of high molecular weight poly(vinyl alcohol) with high yield using low‐temperature solution polymerization of vinyl acetate
Authors: Lyoo Won Seok , Han Sung Soo , Choi Jin Hyun , Ghim Han Do , Yoo Sang Woo , Lee Jinwon , Hong Sung Il , Ha Wan Shik
Published: August 2002

Vinyl acetate (VAc) was solution‐polymerized in tertiary butyl alcohol (TBA) and in dimethyl sulfoxide (DMSO) having low chain transfer constant at 30, 40, and 50°C, using a low temperature initiator, 2,2′‐azobis(2,4‐dimethylvaleronitrile) (ADMVN). The effects of polymerization temperature and initiator concentration were investigated in terms of polymerization behavior and molecular structures of poly(vinyl acetate) (PVAc) and corresponding poly(vinyl alcohol) (PVA) obtained by saponification with sodium hydroxide. The polymerization rates of VAc in TBA and in DMSO were proportional to the 0.49 and 0.72 powers of ADMVN concentration, respectively. For the same polymerization conditions, TBA was absolutely superior to DMSO in increasing the molecular weight of PVA. In contrast, TBA was inferior to DMSO in causing conversion to polymer, indicating that the initiation rate of VAc in TBA was lower than that in DMSO. These effects could be explained by a kinetic order of ADMVN concentration calculated using initial rate method and by an activation energy difference of polymerization obtained from the Arrhenius plot. Low‐temperature solution polymerization of VAc in TBA or DMSO by adopting ADMVN proved successful in obtaining PVA of high molecular weight (number–average degree of polymerization (Pn): 4100–6100) and of high yield (ultimate conversion of VAc into PVAc: 55–80%) with diminishing heat generated during polymerization. In the case of bulk polymerization of VAc at the same conditions, maximum Pn and conversion of 5200–6200 and 20–30% was obtained, respectively. The Pn and lightness were higher, and the degree of branching was lower with PVA prepared from PVAc polymerized at lower temperatures in TBA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1003–1012, 2001