bluuebunny/crossref_metadata_2025 huggingface dataset:
Modified chitosan. I. Optimized cerium ammonium nitrate‐induced synthesis of chitosan‐graft‐polyacrylonitrile
Authors: Pourjavadi A. , Mahdavinia G. R. , Zohuriaan‐Mehr M. J. , Omidian H.
Published: March 2003

Chitin was extracted from shrimp shells and then deacetylated to obtain chitosan. The degree of deacetylation of the chitosan was determined to be 0.76 using pH‐metric titration. A large number of cyanide functional groups were introduced onto chitosan by grafting with polyacrylonitrile as an efficient way of modification. The graft copolymerization reactions were carried out under argon atmosphere in a homogeneous aqueous phase (containing a small portion of acetic acid) by using ceric ammonium nitrate as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of chitosan and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the influential factors, including temperature and concentrations of the initiator, acrylonitrile monomer (AN), acetic acid, and chitosan. The effect of individual factors was investigated by calculating and monitoring the variations of the grafting parameters [i.e., grafting ratio (Gr), grafting efficiency (Ge), add‐on value (Ad), homopolymer content (Hp), and total conversion (Ct)]. Under optimum conditions, the grafting parameters were achieved as 535, 98, 81, 2, and 102%, respectively. A mechanism for the free‐radical grafting was proposed. As empirical rates of polymerization and graft copolymerization were plotted against [AN] and [Ce4+]1/2, the experimental kinetic data displayed a good match to a reported rate statement. The overall activation energy for the graft copolymerization was determined to be 44.9 kJ/mol. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2048–2054, 2003
Controlled rheology of polypropylene: Modeling of molecular weight distributions
Authors: Asteasuain M. , Sarmoria C. , Brandolin A.
Published: March 2003

A mathematical model for the controlled degradation of polypropylene is presented in this article. A previous model of this process was extended to predict the whole molecular weight distribution of the modified resin. Probability generating functions were applied to transform the infinite set of mass balance equations of both polymer and radicals. The integration of the transformed set of equations yielded the probability generating function transforms. These transforms were then inverted with two different inversion algorithms, recovering the molecular weight distributions of the polymer. The model predictions were compared with our experimental data and other information taken from the literature. Good agreement was obtained. The approach presented here is also useful for other polymerization and postpolymerization processes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1676–1685, 2003
Relationship between processing, microstructure, and mechanical properties of injection molded thermotropic LCP
Authors: Wang Y. L. , Yue C. Y. , Tam K. C. , Hu X.
Published: March 2003

A commercial thermotropic liquid crystalline polymer (LCP), Vectra A950, was injection molded into rectangular sheets of thickness ranging from 1 to 4 mm. By changing the thickness of the mold, the shear rate experienced by the TLCP melt in the mold could be varied. The 1‐mm test sample was highly anisotropic while that with larger thickness (4 mm) was less anisotropic. X‐ray diffraction profile at various depths for each of the test sample corresponded to the degree in the fiber orientation present in the test samples. The anisotropy can be described macroscopically by measuring the tensile strength and modulus in the longitudinal and transverse direction. The ratio between the longitudinal and transverse property decreases proportionally to the thickness of the test sample. This reduction corresponded to the reduction in the shear field as the thickness of the mold was increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1713–1718, 2003
High molecular weight hydrophilic functional copolymers by free‐radical copolymerization of acrylamide and ofN‐acryloylmorpholine withN‐acryloxysuccinimide: Application to the synthesis of a graft copolymer
Authors: D'Agosto F. , Charreyre M.‐T. , Mélis F. , Mandrand B. , Pichot C.
Published: March 2003

Free‐radical solution copolymerization of acrylamide (AAm) and of a disubstituted acrylamide derivative,N‐acryloylmorpholine (NAM), with N‐acryloxysuccinimide (NAS) was investigated with the aim to obtain a copolymer of at least 100,000 g mol−1. Different polymerization conditions likely to increase the molecular weight were studied such as monomer and initiator concentrations, temperature, and nature of the solvent. The molecular weights were determined by SEC using a light‐scattering detector. The grafting of end‐functionalized polysaccharide chains onto such high molecular weight poly(NAM‐co‐NAS) was performed and a graft copolymer bearing a high number of saccharidic branches was obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1808–1816, 2003
Graft copolymerisation of N‐vinyl pyrrolidone onto polypropylene copolymer in melt: Effect of grafting on thermomechanical properties and paint adhesion
Authors: Srinivasa Rao G. S. , Jain R. C.
Published: March 2003

N‐vinyl pyrrolidone (NVP) was grafted onto a polypropylene copolymer (PP) in melt in a Brabender Plasticorder and single screw extruder. The effect of variation of dicumyl peroxide (DCP) and lupersol (LUP) concentrations alone and with 20 wt % NVP concentration in the Brabender Plasticorder on Melt Flow Index (MFI) and final torque values was studied. Variation of NVP concentration (1–10 wt %) at a fixed DCP concentration on percent grafting (G) and MFI was also studied in the single screw extruder. The graft copolymers (PP‐g‐NVP) obtained by reaction of PP with NVP were soxhlet extracted with isopropanol to remove homopolymer, dried, and finally characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The PP‐g‐NVP (0–30 wt %) was used as an additive with PP, extruded in the single screw extruder, molded, and the mechanical properties and paint adhesion was measured. MFI values increased and torque values decreased with an increase in initiator concentration, indicating the dominance of the peroxide‐initiated scission reaction over grafting. DCP gave higher grafting compared to LUP. When NVP concentration was increased, MFI values increased initially due to more scission, and then decreased, indicating more graft copolymer formation. Mechanical properties increased by incorporation of PP‐g‐NVP as an additive than PP‐g‐NVP alone. Paint adhesion increased by the presence of PP‐g‐NVP as additive especially with polyurethane primer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2173–2180, 2003
Plasticization of polymers with supercritical carbon dioxide: Experimental determination of glass‐transition temperatures
Authors: Alessi Paolo , Cortesi Angelo , Kikic Ireneo , Vecchione Febe
Published: March 2003

High‐pressure partition chromatography, a modification of the inverse gas chromatography technique, is presented as suitable technique for the study of the plasticization effect of carbon dioxide on the following polymers: poly(methyl methacrylate), polystyrene, and bisphenol A–polycarbonate. Polymers in the presence of a compressed gas or a supercritical fluid become plasticized; this means that their glass‐transition temperatures (Tg's) can be lowered by 10s of degrees, which causes changes in their mechanical and physical properties. CO2‐induced plasticization has an important impact on many polymer processing operations in which the Tg depressions of the polymers can be evaluated. The experimental results are discussed and compared with data available from literature for each polymer we considered. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2189–2193, 2003
Thermosensitive and ampholytic hydrogels for salt solution
Authors: Cai Wensheng , Gupta Ram B.
Published: March 2003

A series of N‐isopropylacrylamide/[[3‐(methacryloylamino)propyl]dimethy(3‐sulfopropyl)ammonium hydroxide] (NIPAAm/MPSA) copolymer hydrogels were prepared with various compositions. Swelling of the hydrogels in water, aqueous NaCl, KCl, CaCl2, and MgCl2 solutions was studied. NIPAAm/MPSA hydrogels have a higher degree of swelling in water and salt solutions than that of poly(N‐isopropylacrylamide) (PNIPAAm). Also, NIPAAm/MPSA hydrogels are more salt resistant when deswelling in salt solutions. For <7 mol % MPSA, the formed hydrogels retain both temperature reversibility and high swelling. A higher content of MPSA (>11 mol %) leads to better salt resistance but a decrease in thermosensitivity. The swelling of NIPAAm/MPSA hydrogel in 0.05M NaCl is non‐Fickian. In NaCl and KCl aqueous solutions, the zwitterionic hydrogels do not show obvious antipolyelectrolyte swelling behavior, whereas in divalent salt CaCl2 and MgCl2 solutions, the swelling ability of NIPAAm/MPSA hydrogels is enhanced at low salt concentration, then decreases with further increase in salt concentration. The lower critical solution temperatures of NIPAAm/MPSA hydrogels are also affected by concentrated salt solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2032–2037, 2003
Viscoelastic behavior in a hydroxyl‐terminated polybutadiene gum and its highly filled composites: Effect of the type of filler on the relaxation processes
Authors: De La Fuente José L. , Fernández‐García Marta , Cerrada María L.
Published: March 2003

Investigations have been ongoing to learn the rheological and/or mechanical behavior of composite solid propellants based on hydroxyl‐terminated polybutadiene (HTPB). The mechanical properties of these materials are related to the macromolecular structure of the binder as well as to the content and nature of the fillers. The viscoelastic behavior of an HTPB binder and its composites with different types of fillers was surveyed by dynamic mechanical analysis over a wide range of temperatures. This technique has clearly demonstrated a two‐phase morphology developed in these systems. The temperature location, intensity, and apparent activation energy of the distinct relaxations are discussed. The dependency of the relaxation processes on filler content in a series of composites has elucidated the interactions between the filler particles and the existing hard‐ and soft‐segment domains within the polyurethane matrix. It was observed that the nature of the filler significantly affects the relaxation process associated with the hard‐segment domains of the polymeric structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1705–1712, 2003
Radiation crosslinking of poly(butylene succinate) in the presence of low concentrations of trimethallyl isocyanurate and its properties
Authors: Suhartini Meri , Mitomo Hiroshi , Nagasawa Naotsugu , Yoshii Fumio , Kume Tamikazu
Published: March 2003

Poly(butylene succinate) (PBS) with different molecular weights was irradiated using an electron beam (EB) in the presence of polyfunctional monomers at ambient temperature. Five polyfunctional monomers were used in this work. The highest amount of gel fraction was achieved when PBS was blended with trimethallyl isocyanurate (TMAIC). The amount of TMAIC introduced strongly influenced the amount of resulting gel. It was determined that the crosslinked PBS sample containing 1% TMAIC had a higher glass‐transition temperature than did the original PBS. It was also observed that the presence of crosslinking bonds in the irradiated PBS greatly improved its heat stability and diminished its ability to biodegradate. Accordingly, it can be concluded that crosslinked PBS in the presence of TMAIC significantly improved its heat resistant properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2238–2246, 2003
Poly(acrylic acid‐co‐vinylsulfonic acid): Synthesis, characterization, and properties as polychelatogen
Authors: Rivas Bernabé L. , Schiappacasse L. Nicolás
Published: March 2003

The synthesis of the water‐soluble poly(acrylic acid‐co‐vinylsulfonic acid) at different feed monomer ratios, while maintaining constant the total number of mol, was carried out by radical polymerization. The copolymers were characterized by FTIR and 1H‐NMR spectroscopies. The copolymer composition was determined by its sulfur content and by potentiometric titration. The metal ion binding properties for Ni(II) and Cu(II) in the aqueous phase were studied using the liquid‐phase polymer‐based retention (LPR) technique for two values of ionic strength. For comparison, the retention properties of both homopolymers were included. The complexing ability of the polymer was determined by the relative amount of carboxylic acid groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1698–1704, 2003
Kinetics of slurry phase polymerization of styrene to syndiotactic polystyrene with pentamethyl cyclopentadienyl titanium trimethoxide and methyl aluminoxane. I. Reaction rate analysis
Authors: Choi Kyu Yong , Chung Jin Suk , Woo Boo Gon , Hong Moo Ho
Published: March 2003

The kinetics of syndiospecific slurry polymerization of styrene in heptane has been investigated with pentamethyl cyclopentadienyl titanium trimethoxide [Cp∗︁Ti(OMe)3] catalyst with methylalmuninoxane. The experimental studies at different styrene/heptane ratios indicate that no global gelation occurs at low styrene/heptane ratios even at high styrene conversion. The effective propagation rate constant tends to decrease as polymerization rate is increased at higher initial styrene concentrations. To analyze the effect of catalyst deactivation, a novel three‐stage polymerization experiment has been designed and carried out where monomer is added during the polymerization. The experimental results show that the catalyst activity is very high at the beginning of polymerization but it decreases significantly as catalyst sites are occluded in the solid phase. We also observe that the catalyst remains active for more than 3 h and the rate decay is not solely due to intrinsic catalyst deactivation. Our experimental data suggests that physical transport effects cause the decay in the polymerization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2132–2137, 2003
Photoresponse gas permeability of azobenzene‐functionalized glassy polymer films
Authors: Kameda Mitsuyoshi , Sumaru Kimio , Kanamori Toshiyuki , Shinbo Toshio
Published: March 2003

The gas permeability of membranes composed of a polymer functionalized with azobenzene chromophores (azopolymer) was investigated under different conditions of light irradiation. A series of measurements with He gas showed that the permeability of the membranes increased by 5–10% upon irradiation with blue light, which caused cyclic photoisomerization of the azobenzene chromophores. In contrast, no significant change in gas permeability and no photoisomerization of the azobenzene chromophores were observed upon irradiation with red light. Moreover, using a digital video microscope, we observed that azopolymer irradiated with blue light spread out from localized particulate domains and thinly covered the surface of the base membrane. Together with the results of the photoresponse permeability measurements, this observation strongly suggested the existence of photoinduced plasticization as discussed in the study of photoinduced surface relief formation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2068–2072, 2003
Preparation of SBS/poly(styrene–methyl methacrylate) thermoplastic interpenetrating polymer network
Authors: Liao Mingyi , Li Keke
Published: March 2003

SBS as polymer I, poly(styrene–methyl methacrylate) polymerized by atom transfer radical polymerization as polymer II, and a thermoplastic interpenetrating polymer network of SBS/poly(styrene–methyl methacrylate) were prepared by the sequential method. The effects of the polymerization temperature, the composition of the catalyst, the ratio of the monomers studied, and the kinetics at 90°C were also investigated. It was shown that when polymerization was initiated by a BPO/CuCl/bpy (BPO:CuCl:bpy = 1:1:3) system at 90°C, the mass averaged molecular weight of the poly(styrene–methyl methacrylate) increased with monomer conversion, and the polydispersities were kept very low. Fourier transform infrared spectroscopy and gel permeation chromatogram showed that poly(styrene–methyl methacrylate) with low polydispersities had been synthesized. Thus, a thermoplastic interpenetrating polymer network comprised of both narrow molecular‐weight‐distribution components was successfully prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2007–2011, 2003
Free‐radical copolymerization of [(4‐isopropyl phenyl) oxycarbonyl] methyl methacrylate with acrylonitrile and methyl methacrylate
Authors: Soykan Cengiz , Erol İbrahim
Published: March 2003

Results of investigations on the synthesis and characterization of free‐radical copolymerization of [(4‐isopropylphenyl) oxycarbonyl] methyl methacrylate (IPPOMMA), monomer (M2) with acrylonitrile (AN), and methyl methacrylate (MMA), monomers (M1) in CHCI3 solution at 60°C with AIBN as initiator are presented. Fourier transform infrared, 1H‐NMR, and elemental analyses techniques were used to identify of polymers. Reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tüdös and Fineman–Ross linearization methods, yielding rAN = 0.60 plusmn; 0.14 and rIPPOMMA = 0.94 ± 0.28 for the AN/IPPOMMA system; rMMA = 0.76 plusmn; 0.30 and rIPPOMMA = 1.08 plusmn; 0.52 for the MMA/IPPOMMA system. The thermal properties of the polymers were studied by thermogravimetric analysis and differential scanning calorimetry. In addition, solubility parameters, inherent viscosities, and densities of polymers were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2331–2338, 2003
Compatibilizing effect of different anhydrides on cane bagasse pith and melamine–formaldehyde‐resin composites
Authors: Mishra S. , Patil Y. P.
Published: March 2003

Melamine–formaldehyde‐resin‐based wood–polymer composites were prepared with cane bagasse pith as a filler. The filler was treated with 1% maleic, phthalic, and succinic anhydrides in xylene separately. The treatment was carried out for different time periods. The effects of the treatment were determined from the acid and ester values of the filler material after every treatment time. Therefore, treated and untreated filler materials (60 wt %) were separately employed for the composite preparation with melamine–formaldehyde as a matrix (40%). Various mechanical tests of the prepared composites showed the effect of the treatment. The mechanical properties were improved by the anhydride treatments up to a particular period of the treatment. Each of the anhydrides had a profound effect on the peculiar mechanical properties. Of the three anhydrides, succinic anhydride and phthalic anhydride appeared to be better compatibilizers for a treatment period of 2 h at a concentration of 1% in xylene. The inconsistency in the acid values and mechanical properties beyond 2 h of treatment with the anhydrides was due to chemisorption and desorption phenomena. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1768–1774, 2003
Serotonin in the rabbit ileum: Localization, uptake, and effect on motility
Authors: Dénes Viktória , Lázár Zsófia , Barthó Loránd , Gábriel Robert
Published: March 2003

Repeated experiments to localise serotonin in the myenteric plexus of rabbit ileum failed. After preincubation in serotonin (10−5 M), an extensive varicose fibre system was detected by immunocytochemical methods. Stained fibres left the myenteric plexus and ran to the muscle layers. Labelled cell bodies could not be found, even after pretreatment with colchicine or pargyline. Application of reserpine (10−5 M) and fluoxetine (10−5 M) prevented serotonin uptake. Antisera against tryptophan hydroxylase revealed a rich fibre system, including those processes that entered the tertiary plexus. These fibres were able to accumulate serotonin, but again the cell bodies could not be detected. Serotonin caused concentration‐dependent contraction in the longitudinal muscle layer of the rabbit ileum. Pretreatment with tetrodotoxin strongly reduced the effect of serotonin. Preapplication of atropine caused a slight decrease of response evoked by serotonin. Combined administration of tetrodotoxin and atropine significantly reduced the responses to serotonin, but did not abolish them. At the same time, agonists of 5‐HT2 and 5‐HT4 receptors caused concentration‐dependent contractions. Our studies show that: 1) Without pretreatment, serotonin cannot be detected in the myenteric plexus of rabbit ileum. 2) An extensive uptake system works in this plexus. If released from myenteric nerve fibres, serotonin may evoke contractions in indirect and direct ways. 3) There may be an extrinsic serotoninergic innervation from the mesenteric ganglia. 4) Serotonin exerts its effect through 5‐HT2 and 5‐HT4 receptors on smooth muscle cells and nerve elements. Anat Rec Part A 271A:368–376, 2003. © 2003 Wiley‐Liss, Inc.
Olfactory ensheathing cells: Historical perspective and therapeutic potential
Authors: Boyd J.G. , Skihar V. , Kawaja M. , Doucette R.
Published: March 2003

Olfactory ensheathing cells (OECs) are the glial cells that ensheath the axons of the first cranial nerve. They are attracting increasing attention from neuroscientists as potential therapeutic agents for use in the repair of spinal cord injury and as a source of myelinating glia for use in remyelinating axons in demyelinating diseases such as multiple sclerosis. This review mainly addresses the cell biological aspects of OECs pertinent to addressing two questions. Namely, where do OECs fit into the groupings of central nervous system (CNS)/peripheral nervous system (PNS) glial cells and should OECs be viewed as a clinically relevant alternative to Schwann cells in the treatment of spinal cord injury? The evidence indicates that OECs are indeed a clinically relevant alternative to Schwann cells. However, much more work needs to be done before we can even come close to answering the first question as to the lineage and functional relationship of OECs to the other types of CNS and PNS glial cells. Anat Rec (Part B: New Anat) 271B:49–60, 2003. © 2003 Wiley‐Liss, Inc.
Ethnic and sex differences in serum levels of cartilage oligomeric matrix protein: The Johnston county osteoarthritis project
Authors: Jordan Joanne M. , Luta Gheorghe , Stabler Thomas , Renner Jordan B. , Dragomir Anca D. , Vilim Vladimir , Hochberg Marc C. , Helmick Charles G. , Kraus Virginia B.
Published: March 2003

Objective

Previous descriptions of potential biomarkers of osteoarthritis (OA) have been limited to Caucasians. In the present study, we examined associations between serum levels of cartilage oligomeric matrix protein (COMP) and ethnicity (African American or Caucasian) and sex in the Johnston County Osteoarthritis Project, a population‐based study of OA in rural North Carolina.

Methods

All African Americans and a randomly selected sample of Caucasians who had available sera and either no radiographic evidence of knee or hip OA according to the Kellgren/Lawrence (K/L) system (K/L grade 0) or radiographic evidence of knee OA (K/L grade 2 or higher) were included. Serum COMP levels were quantified by sandwich enzyme‐linked immunosorbent assay, using monoclonal antibodies 16‐F12 and 17‐C10. Linear regression models were used to assess relationships between serum levels of natural log–transformed COMP (ln COMP) and ethnicity and sex, controlling for age, height, body mass index (BMI), radiographic OA, and the presence of other symptomatic joints. Radiographic OA was defined in separate models as the presence, severity, and laterality of radiographic knee OA, the co‐occurrence of radiographic knee and hip OA, and the number of knees and hips with radiographic OA.

Results

The 769 subjects in the study sample had a mean ± SD age of 62 ± 10.3 years. Levels of ln COMP were associated with age, BMI, and all definitions of radiographic OA (P = 0.0001), and varied by ethnicity and sex. In adjusted models, ln COMP was higher in African American women than in Caucasian women (P = 0.003) and higher in Caucasian men than Caucasian women (P = 0.0001). There were no statistically significant differences in serum ln COMP levels between African American men and women.

Conclusion

Serum COMP levels vary by ethnicity and sex. These factors should be considered in the derivation of standards using this, and possibly other, potential biomarkers of OA.
Are environmental factors important in primary systemic vasculitis?: A case–control study
Authors: Lane Suzanne E. , Watts Richard A. , Bentham Graham , Innes Nicholas J. , Scott David G. I.
Published: March 2003

Objective

To investigate the association between primary systemic vasculitis (PSV) and environmental risk factors.

Methods

Seventy‐five PSV cases and 273 controls (220 nonvasculitis, 19 secondary vasculitis, and 34 asthma controls) were interviewed using a structured questionnaire. Factors investigated were social class, occupational and residential history, smoking, pets, allergies, vaccinations, medications, hepatitis, tuberculosis, and farm exposure in the year before symptom onset (index year). The Standard Occupational Classification 2000 and job‐exposure matrices were used to assess occupational silica, solvent, and metal exposure. Stepwise multiple logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (95% CI) adjusted for potential confounders. Total PSV, subgroups (47 Wegener's granulomatosis [WG], 12 microscopic polyangiitis, 16 Churg‐Strauss syndrome [CSS]), and antineutrophil cytoplasmic antibody (ANCA)–positive cases were compared with control groups.

Results

Farming in the index year was significantly associated with PSV (OR 2.3 [95% CI 1.2–4.6]), with WG (2.7 [1.2–5.8]), with MPA (6.3 [1.9–21.6]), and with perinuclear ANCA (pANCA) (4.3 [1.5–12.7]). Farming during working lifetime was associated with PSV (2.2 [1.2–3.8]) and with WG (2.7 [1.3–5.7]). Significant associations were found for high occupational silica exposure in the index year (with PSV 3.0 [1.0–8.4], with CSS 5.6 [1.3–23.5], and with ANCA 4.9 [1.3–18.6]), high occupational solvent exposure in the index year (with PSV 3.4 [0.9–12.5], with WG 4.8 [1.2–19.8], and with classic ANCA [cANCA] 3.9 [1.6–9.5]), high occupational solvent exposure during working lifetime (with PSV 2.7 [1.1–6.6], with WG 3.4 [1.3–8.9], and with cANCA 3.3 [1.0–10.8]), drug allergy (with PSV 3.6 [1.8–7.0], with WG 4.0 [1.8–8.7], and with cANCA 4.7 [1.9–11.7]), and allergy overall (with PSV 2.2 [1.2–3.9], with WG 2.7 [1.4–5.7]). No other significant associations were found.

Conclusion

A significant association between farming and PSV has been identified for the first time. Results also support previously reported associations with silica, solvents, and allergy.
Mitochondrial respiratory activity is altered in osteoarthritic human articular chondrocytes
Authors: Maneiro Emilia , Martín Miguel A. , de Andres María C. , López‐Armada Maria J. , Fernández‐Sueiro José L. , del Hoyo Pilar , Galdo Fausto , Arenas Joaquin , Blanco Francisco J.
Published: March 2003

Objective

Osteoarthritis (OA) is a degenerative rheumatic disease that is associated with extracellular matrix degradation and chondrocyte apoptosis in the articular cartilage. The role of mitochondria in degenerative diseases is widely recognized. We undertook this study to evaluate mitochondrial function in normal and OA chondrocytes and to examine age‐related changes in mitochondria.

Methods

Mitochondrial function was evaluated by analyzing respiratory chain enzyme complexes and citrate synthase (CS) activities as well as changes in mitochondrial membrane potential (ΔΨm). The activities of mitochondrial respiratory chain complexes (complex I: rotenone‐sensitive NADH–coenzyme Q1 reductase; complex II: succinate dehydrogenase; complex III: antimycin‐sensitive ubiquinol cytochrome c reductase; and complex IV: cytochrome c oxidase) and CS were measured in human articular chondrocytes isolated from OA and normal cartilage. ΔΨm was measured by JC‐1 using flow cytometry. Statistical analysis was performed using the Mann‐Whitney U test and Student's t‐test as well as several models of multiple linear regression.

Results

OA articular chondrocytes had reduced activities of complexes II and III compared with cells from normal cartilage. However, the mitochondrial mass was increased in OA. Cultures of OA chondrocytes contained a higher proportion of cells with de‐energized mitochondria. We found no relationship between mitochondrial function and donor age either in normal or in OA chondrocytes.

Conclusion

These findings suggest the involvement of mitochondrial function in the pathophysiology of OA. Cartilage degradation by OA and cartilage aging may be two different processes.
A short course of BG9588 (anti–CD40 ligand antibody) improves serologic activity and decreases hematuria in patients with proliferative lupus glomerulonephritis
Authors: Boumpas Dimitrios T. , Furie Richard , Manzi Susan , Illei Gabor G. , Wallace Daniel J. , Balow James E. , Vaishnaw Akshay ,   on behalf of the BG9588 Lupus Nephritis Trial Group
Published: March 2003

Objective

CD40–CD40 ligand (CD40L) interactions play a significant role in the production of autoantibodies and tissue injury in lupus nephritis. We performed an open‐label, multiple‐dose study to evaluate the safety, efficacy, and pharmacokinetics of BG9588, a humanized anti‐CD40L antibody, in patients with proliferative lupus nephritis. The primary outcome measure was 50% reduction in proteinuria without worsening of renal function.

Methods

Twenty‐eight patients with active proliferative lupus nephritis were scheduled to receive 20 mg/kg of BG9588 at biweekly intervals for the first 3 doses and at monthly intervals for 4 additional doses. Safety evaluations were performed on all patients. Eighteen patients receiving at least 3 doses were evaluated for efficacy.

Results

The study was terminated prematurely because of thromboembolic events occurring in patients in this and other BG9588 protocols (2 myocardial infarctions in this study). Of the 18 patients for whom efficacy could be evaluated, 2 had a 50% reduction in proteinuria without worsening of renal function. Mean reductions of 38.9% (P < 0.005), 50.1% (P < 0.005), and 25.3% (P < 0.05) in anti–double‐stranded DNA (anti‐dsDNA) antibody titers were observed at 1, 2, and 3 months, respectively, after the last treatment. There was a significant increase in serum C3 concentrations at 1 month after the last dose (P < 0.005), and hematuria disappeared in all 5 patients with significant hematuria at baseline. There were no statistically significant reductions in lymphocyte count or serum immunoglobulin, anticardiolipin antibody, or rubella IgG antibody concentrations after therapy.

Conclusion

A short course of BG9588 treatment in patients with proliferative lupus nephritis reduces anti‐dsDNA antibodies, increases C3 concentrations, and decreases hematuria, suggesting that the drug has immunomodulatory action. Additional studies will be needed to evaluate its long‐term effects.
Randomized study of subcutaneous low molecular weight heparin plus aspirin versus intravenous immunoglobulin in the treatment of recurrent fetal loss associated with antiphospholipid antibodies
Authors: Triolo Giovanni , Ferrante Angelo , Ciccia Francesco , Accardo‐Palumbo Antonina , Perino Antonino , Castelli Antonio , Giarratano Antonio , Licata Giuseppe
Published: March 2003

Objective

To compare the 2 most efficacious therapeutic regimens, intravenous immunoglobulin (IVIG) and anticoagulation with low molecular weight (LMW) heparin plus low‐dose aspirin, in women with recurrent pregnancy loss associated with antiphospholipid antibodies (aPL).

Methods

We examined 40 women with recurrent abortion (at least 3 occurrences) and repeatedly positive test results for anticardiolipin or lupus anticoagulant. The subjects were randomly assigned to treatment with IVIG or LMW heparin plus low‐dose aspirin. Both therapies were started when the women were pregnant as documented by a positive urine test. IVIG was stopped at the thirty‐first week of gestation, aspirin at the thirty‐fourth week, and heparin at the thirty‐seventh week. The primary outcome of interest was the rate of live births with the 2 treatments.

Results

The characteristics of the 2 groups were similar at the time of randomization. The women treated with LMW heparin plus low‐dose aspirin had a higher rate of live births (84%) than those treated with IVIG (57%).

Conclusion

Treatment with LMW heparin plus low‐dose aspirin should be considered as the standard therapy for recurrent pregnancy loss due to aPL.
Predicting future citation behavior
Authors: Burrell Quentin L.
Published: March 2003

In this article we further develop the theory for a stochastic model for the citation process in the presence of obsolescence to predict the future citation pattern of individual papers in a collection. More precisely, we investigate the conditional distribution—and its mean—of the number of citations to a paper after time t, given the number of citations it has received up to time t. In an important parametric case it is shown that the expected number of future citations is a linear function of the current number, this being interpretable as an example of a success‐breeds‐success phenomenon.
Paradigms, citations, and maps of science: A personal history
Authors: Small Henry
Published: March 2003

Can maps of science tell us anything about paradigms? The author reviews his earlier work on this question, including Kuhn's reaction to it. Kuhn's view of the role of bibliometrics differs substantially from the kinds of reinterpretations of paradigms that information scientists are currently advocating. But these reinterpretations are necessary if his theory will ever be empirically tested, and further progress is to be made in understanding the growth of scientific knowledge. A new Web tool is discussed that highlights rapidly changing specialties that may lead to new ways of monitoring revolutionary change in real time. It is suggested that revolutionary and normal science be seen as extremes on a continuum of rates of change rather than, as Kuhn originally asserted, as an all or none proposition.
Pathfinder networks and author cocitation analysis: A remapping of paradigmatic information scientists
Authors: White Howard D.
Published: March 2003

In their 1998 article “Visualizing a discipline: An author cocitation analysis of information science, 1972–1995,” White and McCain used multidimensional scaling, hierarchical clustering, and factor analysis to display the specialty groupings of 120 highly‐cited (“paradigmatic”) information scientists. These statistical techniques are traditional in author cocitation analysis (ACA). It is shown here that a newer technique, Pathfinder Networks (PFNETs), has considerable advantages for ACA. In PFNETs, nodes represent authors, and explicit links represent weighted paths between nodes, the weights in this case being cocitation counts. The links can be drawn to exclude all but the single highest counts for author pairs, which reduces a network of authors to only the most salient relationships. When these are mapped, dominant authors can be defined as those with relatively many links to other authors (i.e., high degree centrality). Links between authors and dominant authors define specialties, and links between dominant authors connect specialties into a discipline. Maps are made with one rather than several computer routines and in one rather than many computer passes. Also, PFNETs can, and should, be generated from matrices of raw counts rather than Pearson correlations, which removes a computational step associated with traditional ACA. White and McCain's raw data from 1998 are remapped as a PFNET. It is shown that the specialty groupings correspond closely to those seen in the factor analysis of the 1998 article. Because PFNETs are fast to compute, they are used in AuthorLink, a new Web‐based system that creates live interfaces for cocited author retrieval on the fly.
Simultaneous mapping of interactions between scientific and technological knowledge bases: The case of space communications
Authors: Hassan E.
Published: March 2003

This article examines the knowledge structure of the field of space communications using bibliometric mapping techniques based on textual analysis. A new approach with the aim of visualizing simultaneously the configuration of its scientific and technological knowledge bases is presented. This approach enabled us to overcome various limits of existing bibliometric methods dealing with science and technology relationships. The bibliometric map revealed weak cognitive interactions between science and technology at the worldwide level, although it brought out the systemic nature of the process of knowledge production at either side. We extended the mapping approach to the R&D activities of the Triad countries in order to characterize their specialization profiles and cognitive links on both sides in comparison with the structure of the field at the worldwide level. Results showed different patterns in the way the Triad countries organized their scientific and technological activities within the field.
Characterisation of the human liver in vitro metabolic pattern of artemisinin and auto‐induction in the rat by use of nonlinear mixed effects modelling
Authors: Svensson Ulrika S.H. , Mäki‐Jouppila Mika , Hoffmann Kurt‐Jürgen , Ashton Michael
Published: March 2003

Aims: The aims of the study were to characterise the metabolic pattern of artemisinin in human and rat liver microsomes and to assess the magnitude of auto‐induction in the rat.

Methods: 14C‐artemisinin was incubated with human liver microsomes and with liver microsomes from rats pretreated with oral artemisinin or placebo. The metabolic fate of 14C‐artemisinin in microsomes from human B‐lymphoblastoid cell lines transformed with CYP2A6, CYP2B6 and CYP3A4 was also investigated. The human liver microsome data and the rat liver microsomes data were analysed by nonlinear mixed effects modelling and naïve pooling using NONMEM, respectively.

Results: Four metabolites were radiometrically detected in experiments with rat liver microsomes. The model that best described the data involved three primary metabolites of which one metabolite was further metabolised to a secondary metabolite. The formation of the four metabolites was induced 2.8, 7.2, 4.8 and 2.5‐fold, respectively, in liver microsomes from rats pre‐treated with artemisinin. Three metabolites were formed in human liver microsomes; having the same retention times as three of the metabolites formed in the rat. The final model consisted of two primary metabolites and a secondary metabolite with CYP2B6 and CYP2A6 influencing the formation rates of the major and minor primary metabolites, respectively.

Conclusions: CYP2B6 and CYP2A6 activities described variability in the formation of the major and minor primary metabolites, respectively, in human liver microsomes. All artemisinin metabolic pathways in rat liver microsomes were induced in artemisinin pretreated animals. We suggest modelling as a method for the discrimination and detection of more complex metabolic patterns from in vitro metabolism rate data. Copyright © 2002 John Wiley & Sons, Ltd.
Microfiltration and ultrafiltration of polysaccharides produced by fermentation using a rotating disk dynamic filtration system
Authors: Brou A. , Jaffrin M. Y. , Ding L. H. , Courtois J.
Published: March 2003

The recovery of exopolysaccharides (EPS) produced by Sinorhizobium meliloti bacteria by dynamic microfiltration was investigated using a rotating disk device designed in our laboratory, equipped with a 0.2 μm nylon membrane. This system differs from commercially available systems by the presence of vanes on the disk which produce a very important increase in permeate flux while yielding excellent EPS transmission. For polymers produced under standard fermentation conditions (70 h at 30°C), the mass flux rose to 650 g h−1 m−2 using a disk equipped with 2 mm vanes rotating at 2000 rpm against 380 g h−1 m−2 with a smooth disk at the same speed. The maximum flux observed was 1560 g h−1 m−2 with a 6‐mm vanes disk rotating at 3000 rpm and a 36°C broth. An interesting finding was that the permeate flux Jf for various disks can be correlated by the same function of the mean shear stress at the membrane τwm according to Jf = 4.6 τwm0.717 for a 30°C broth, showing that the effect of vanes is merely to increase the shear stress by raising the fluid core velocity between the membrane and the disk. With 6‐mm vanes the core angular velocity was found to be 84% of disk velocity vs. 45% for a smooth disk. When the fermentation temperature was increased to 36°C to produce a lower molecular weight polymer, the permeate flux rose by about 250%, much more than what could be expected from the reduction in permeate viscosity and followed the same power law with membrane shear stress as for 30°C. The same device was equipped with a PES 50 kDa membrane to concentrate EPS by ultrafiltration. Permeate fluxes were of the order of 160 L h−1 m−2 at 2000 rpm and 30°C with nearly complete EPS rejection. Finally, the net electrical power consumed by the disk was measured by subtracting the power consumed without fluid from the power during filtration at the same speed. This power increases with speed and with the presence of vanes, but since the gain provided by the vanes is very high, the specific energy per m3 of permeate is minimal with the highest vanes tested (6 mm) and maximal for smooth disks. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 429–437, 2003.
Laser impact assessment in a biofilm‐forming bacterium Pseudoalteromonas carrageenovora using a flow cytometric system
Authors: Nandakumar Kanavillil , Obika Hideki , Shinozaki Tatsuya , Ooie Toshihiko , Utsumi Akihiro , Yano Tetsuo
Published: March 2003

Impact by pulsed laser irradiations from an Nd:YAG laser on the marine biofilm‐forming bacterium Pseudoalteromonas carrageenovora has been studied using a flow cytometric system. The biofilm‐forming bacteria in the planktonic state have been irradiated while flowing, and the mortality and bacterial attachment have been determined by exposing TiN coupons in the system. Coupons suspended in the non‐irradiated bacterial flow were treated as the control. The fluence used in the study was 0.1 J/cm2. Three flow rates (14, 28, and 42 cm/min) and two exposure durations (15 and 30 min) were tested. The results showed the increase in bacterial mortality with the decrease in flow rate. The maximum mortality of 27.5% was observed when the flow rate was 14 cm/min. The bacterial attachment increased with the increase in flow rate and exposure duration. The area of bacterial attachment on the experimental coupons exposed to the irradiated sample was significantly lesser than that for the nonirradiated sample. The results thus show in a flowing system, low power pulsed laser irradiations could reduce the bacterial attachment even though it did not cause significant mortality. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 399–402, 2003.
Glucose‐6‐phosphate dehydrogenase partitioning in two‐phase aqueous mixed (nonionic/cationic) micellar systems
Authors: Rangel‐Yagui Carlota O. , Lam Henry , Kamei Daniel T. , Wang Daniel I. C. , Pessoa Adalberto , Blankschtein Daniel
Published: March 2003

The enzyme glucose‐6‐phosphate dehydrogenase (G6PD) plays an important role in maintaining the level of NADPH and in producing pentose phosphates for nucleotide biosynthesis. It is also of great value as an analytical reagent, being used in various quantitative assays. In searching for new strategies to purify this enzyme, the partitioning of G6PD in two‐phase aqueous mixed (nonionic/cationic) micellar systems was investigated both experimentally and theoretically. Our results indicate that the use of a two‐phase aqueous mixed micellar system composed of the nonionic surfactant C10E4 (n‐decyl tetra(ethylene oxide)) and the cationic surfactant CnTAB (alkyltrimethylammonium bromide, n = 8, 10, or 12) can improve significantly the partitioning behavior of G6PD relative to that obtained in the two‐phase aqueous C10E4 micellar system. This improvement can be attributed to electrostatic attractions between the positively charged mixed (nonionic/cationic) micelles and the net negatively charged enzyme G6PD, resulting in the preferential partitioning of G6PD to the top, mixed micelle‐rich phase of the two‐phase aqueous mixed micellar systems. The effect of varying the cationic surfactant tail length (n = 8, 10, and 12) on the denaturation and partitioning behavior of G6PD in the C10E4 /CnTAB/buffer system was investigated. It was found that C8TAB is the least denaturing to G6PD, followed by C10TAB and C12TAB. However, the C10E4/C12TAB/buffer system generated stronger electrostatic attractions with the net negatively charged enzyme G6PD than the C10E4/C10TAB/buffer and the C10E4/C8TAB/buffer systems, when using the same amount of cationic surfactant. Overall, the two‐phase aqueous mixed (C10E4/C10TAB) micellar system yielded the highest G6PD partition coefficient of 7.7, with a G6PD yield in the top phase of 71%, providing the optimal balance between the denaturing effect and the electrostatic attractions for the three cationic surfactants examined. A recently developed theoretical framework to predict protein partition coefficients in two‐phase aqueous mixed (nonionic/ionic) micellar systems was implemented, and the theoretically predicted G6PD partition coefficients were found to be in reasonable quantitative agreement with the experimentally measured ones. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 445–456, 2003.
Coextraction during reactive extraction of phenylalanine using Aliquat 336: Modeling extraction equilibrium
Authors: Pursell Mark R. , Mendes‐Tatsis M. Alcina , Stuckey David C.
Published: March 2003

Reactive liquid–liquid extraction can be used to recover hydrophilic fermentation products that would not otherwise partition into nonpolar solvents through an ion‐exchange reaction at the two‐phase interface. However, the ion‐exchange reagent may not be specific to the solute of interest and other compounds present may also be extracted. In this study, the effect on solute extraction of other compounds present in the extraction medium was investigated for phenylalanine extraction using Aliquat 336. The extent of extraction at equilibrium was modeled using the equilibrium constants for the reactions present in the process. The interaction of different species within a multicomponent medium was examined using the model and experimental results. It was found that the extent of extraction and coextraction is controlled by the thermodynamics of each extraction reaction and, due to the formation of a common product, the interaction between each of the reactions. The main competition to reactive extraction will come from hydrophobic anionic compounds that will be present in fermentation broth. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 533–542, 2003.