bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surrogate‐stoppered [2]rotaxanes: a new route to larger interlocked architectures
Authors: Rowan Stuart J. , Stoddart J. Fraser 
Published: January 2003

AbstractA novel synthetic strategy for exchanging stoppers on rotaxanes, without them losing their integrity as interlocked molecules, is presented. The surrogate‐stoppered [2]rotaxane contains one inert stopper and a triphenylphosphonium group attached to a benzylic position as a second reactive stopper in the dumbbell‐shaped component which contains an ammonium (NH2+) ion recognition site, encircled by a crown ether (24C8 or 25C8) component. The strategy for exchanging stoppers relies upon the ability of a benzylic triphenylphosphonium function to undergo a Wittig reaction with a bulky aromatic aldehyde to form a ‘stilbenoid’ [2]rotaxane as a mixture of cis and trans isomers, without the occurrence of any dethreading of the crown ether ring component. The CC double bonds can then be hydrogenated, using Adams' catalyst, to afford a new covalently modified [2]rotaxane with two inert stoppers. Utilizing this strategy, larger interlocked molecular structures including a two‐stationed [2]rotaxane and a branched [4]rotaxane have been prepared. Furthermore, initial studies, aimed at using this methodology to gain access to poly[n]rotaxane architectures, are presented. Two ammonium ion/crown ether‐based [2]rotaxane monomers–each incorporating (i) a dumbbell‐shaped component, possessing the surrogate benzylic triphenylphosphonium stopper, and (ii) a crown ether ring component, bearing an aldehyde function on a fused benzenoid ring–undergo a sequence of Wittig reactions in which the surrogate benzylic triphenylphosphonium stopper is exchanged for a crown ether ring component either, (i) in the same rotaxane molecule, to give cyclic daisy‐chains by an intramolecular, chain‐terminating reaction or, (ii) in another rotaxane molecule, to give acyclic daisy chains by an intermolecular chain‐propagating reaction. Copyright © 2003 John Wiley & Sons, Ltd.
Double emulsions stabilized by new molecular recognition hybrids of natural polymers
Authors: Benichou Axel , Aserin Abraham , Garti Nissim 
Published: January 2003

AbstractWater‐in‐oil‐in‐water (W/O/W) double emulsions with improved stability and less polydispersity in droplet size distribution were prepared using polyglycerol polyricinoleate (PGPR) as emulsifier in the inner aqueous phase and replacing the common nonionic hydrophilic monomeric emulsifiers by a “protein–polysaccharide hybrid” in the outer interface.Amphiphilic macromolecular hybrids with specific interfacial recognition capabilities to be termed “biomacro‐molecular‐recognition hybrids” have been prepared in aqueous solution by interacting whey protein isolate (WPI) with hydrocolloids (xanthan gum, galactomannans) at selected pH and weight ratios. The binary aqueous mixtures do not coacervate or precipitate but form stable molecular adducts.At pH lower than the isoelectric point of the protein (pH 4.6), the yield of encapsulation of glucose (a model marker) in the inner phase of the double emulsion is close to 95%. The emulsion droplets are stabilized by both steric and electrostatic contributions (zeta potential is close to +30 mV). Rheological measurements indicate that, at low pH, such systems behave as viscous ones with G″ (loss modulus) greater than G′ (storage modulus). When the pH is close or greater than the isoelectric point of the protein, the system exhibits a more pronounced elastic behavior (G′ < G″) that can explain the reduction in emulsification capabilities of such mixtures. In this case the yield of encapsulation is less than 10% and the double emulsion droplets are larger than 10 µm.At pH ≤ 2, the adducts can efficiently stabilize double emulsions and serve as an efficient and thick barrier against the release of vitamin B1 entrapped in the core of the W/O/W double emulsions. The release of the vitamin was less than 18% after three weeks of storage at room temperature (against 100% of release at neutral pH). Copyright © 2003 John Wiley & Sons, Ltd.
Networks for recognition of biomolecules: molecular imprinting and micropatterning poly(ethylene glycol)‐ Containing films
Authors: Byrne Mark E. , Oral Ebru , Zachary Hilt J. , Peppas Nicholas A. 
Published: January 2003

AbstractEngineering the molecular design of biomaterials by controlling recognition and specificity is the first step in coordinating and duplicating complex biological and physiological processes. Studies of protein binding domains reveal molecular architectures with specific chemical moieties that provide a framework for selective recognition of target biomolecules in aqueous environment. By matching functionality and positioning of chemical residues, we have been successful in designing biomimetic polymer networks that specifically bind biomolecules in aqueous environments. Our work addresses the preparation, behavior, and dynamics of the three‐dimensional structure of biomimetic polymers for selective recognition via non‐covalent complexation. In particular, the synthesis and characterization of recognitive gels for the macromolecular recognition of D‐glucose is highlighted. Novel copolymer networks containing poly(ethylene glycol) (PEG) and functional monomers such as acrylic acid, 2‐hydroxyethyl methacrylate, and acrylamide were synthesized in dimethyl sulfoxide (polar, aprotic solvent) and water (polar, protic solvent) via UV‐free radical polymerization. Polymers were characterized by single and competitive equilibrium and kinetic binding studies, single and competitive fluorescent and confocal microscopy studies, dynamic network swelling studies, and ATR‐FTIR. Results qualitatively and quantitatively demonstrate effective glucose‐binding polymers in aqueous solvent. Owing to the presence of template, the imprinting process resulted in a more macroporous structure as exhibited by dynamic swelling experiments and confocal microscopy. Polymerization kinetic studies suggest that the template molecule has more than a dilution effect on the polymerization, and the effect of the template is related strongly to the rate of propagation. In addition, PEG containing networks were micropatterned to fabricate microstructures, which would be the basis for micro‐diagnostic and tissue engineering devices. Utilizing photolithography techniques, polymer micropatterns of a variety of shapes and dimensions have been created on polymer and silicon substrates using UV free‐radical polymerizations with strict spatial control. Micropatterns were characterized using optical microscopy, SEM, and profilometry. The processes and analytical techniques presented are applicable to other stimuli‐sensitive and recognitive networks for biomolecules, in which hydrogen bonding, hydrophobic, or ionic contributions will direct recognition. Further developments are expected to have direct impact on applications such as analyte controlled and modulated drug and protein delivery, drug and biological elimination, drug targeting, tissue engineering, and micro‐ or nano‐devices. This work is supported by NSF Grant DGE‐99‐72770. Copyright © 2003 John Wiley & Sons, Ltd.
Enzymatically controlled responsive drug delivery systems
Authors: Goldbart Riki , Traitel Tamar , Lapidot Smadar A. , Kost Joseph 
Published: January 2003

AbstractThis paper discusses two approaches for the preparation of enzymatically controlled drug delivery systems: (i) a calcium‐responsive biodegradable drug delivery system based on a mixture of starch with HPMC (hydroxypropyl methyl cellulose ether) (biodegradable) and the starch hydrolytic enzyme, α‐amylase, in its non‐active form; (ii) a glucose‐responsive insulin delivery system based on the hydrogel poly(2‐hydroxyethyl methacrylate‐co‐N,N‐dimethylaminoethyl methacrylate), with entrapped glucose oxidase, catalase and insulin. In both systems, the sensitivity to a trigger molecule (calcium or glucose) was achieved by the incorporation of a specific enzyme that reacts with the trigger molecule. Based on these interactions we propose two different enzyme‐controlled drug release mechanisms for responsive drug delivery systems. Copyright © 2003 John Wiley & Sons, Ltd.
Differential scanning calorimetry studies on poly(ethylene glycol) with different molecular weights for thermal energy storage materials
Authors: Pielichowski Krzysztof , Flejtuch Kinga 
Published: January 2003

AbstractMelting and crystallization behaviour of poly(ethylene glycol) (PEG) with different molecular weights (from 1000 to 35 000) and chosen blends of PEG is investigated by means of differential scanning calorimetry (DSC) operating in dynamic mode at different heating rates. The influence of the molecular weight of PEG on its melting point and enthalpy of fusion is evaluated; from the DSC data the degree of crystallinity is calculated–it is found that there is an increased tendency of higher‐molecular‐weight PEGs towards the formation of crystalline phase owing to their lower segmental mobility and more convenient geometrical alignment. During the freezing cycle, an increase in the molecular weight of PEG causes an increase in the solidification temperature and heat of crystallization. Thermal transition data are supplemented by optical microscopy–numerous small sphere‐shaped crystalline structures are observed to join together and impinge on their neighbours, forming eventually a multilayered lamellar texture. By implementing second polymeric component the polydispersity of the system increases, thus lowering the crystallization degree during preparation phase. It influences also the course of solidification by lowering the crystallization temperature, Tc. An additional effect observed in the case of the blend's freezing is associated with larger supercooling, probably due to morphological constraints and entanglements in interlamellar regions. The possible advantage of using PEG blends to replace pure components is connected with the possibility of changing the temperature range and heat associated with melting/freezing. Copyright © 2003 John Wiley & Sons, Ltd.
New types of microspheres and microsphere‐related materials for medical diagnostics
Authors: Slomkowski Stanislaw , Basinska Teresa , Miksa Beata 
Published: January 2003

AbstractPolymer microspheres are used in diagnostics as “reagents” and as elements of diagnostic devices. In this paper we compare properties of microspheres with aldehyde, carboxyl and hydroxyl groups in their surface layers. Microspheres with aldehyde groups were obtained by radical emulsion copolymerization of styrene and acrolein and in sequential redox polymerization of pyrrole followed with radical polymerization of acrolein. Microspheres with hydroxyl groups were synthesized by radical emulsion copolymerization of styrene and α‐t‐butoxy‐ω‐vinylbenzyl‐polyglycidol macromonomer.­Microspheres with hydroxyl and carboxyl groups were synthesized by radical emulsion copolymerization of methylmethacrylate, acrylic acid and 2‐hydroxyethylmethacrylate. X‐Ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) revealed that microspheres had the core–shell morphology with surface layers enriched in polymeric units with reactive groups. The above mentioned microspheres were used as supports for adsorption and covalent immobilization of human and animal proteins–human serum albumin (HSA), gamma globulins (γG; human, rabbit and goat), human fibrinogen (Fb), and enzymes: glucose oxidase (GOD) and urease (Urs). The applicability of microspheres with attached antigens and/or antibodies (γG) for turbidimetric aggregation tests and for a new type of test based on changes of electrophoretic mobility of microspheres is discussed. Potential applications of microspheres with immobilized enzymes for the construction of biosensors are described. Copyright © 2003 John Wiley & Sons, Ltd.
Discriminative validity of the behavior assessment system for children‐parent rating scales in children with recurrent abdominal pain and matched controls
Authors: ROBINS PAUL M. , SCHOFF KRISTIN M. , GLUTTING JOSEPH J. , ABELKOP A. SHAYNE 
Published: January 2003

AbstractExamined discriminative validity of the Parent Rating Scale (PRS) of the Behavior Assessment System for Children (BASC; Reynolds & Kamphaus, 1992, Circle Pines, MN: American Guidance Services). Two groups were compared: a cohort with recurrent abdominal pain (RAP) (n= 49) and children from the BASC‐PRS standardization sample (n = 49) matched on the background characteristics of age, race/ethnicity, and gender. A multivariate, two‐group discriminant function analysis was used to compare groups across standard scores from the nine clinical scales of the PRS. Results demonstrated that children with RAP could be differentiated (Wilks λ = .642, F = 6.45, df (9, 88), p < .001), and demonstrated higher scores on the Somatization, Depression, Anxiety, Attention Problems, and Withdrawal scales. Subsequent jackknifed classification analysis, diagnostic efficiency statistics, and an odds ratio for the classification analysis added to the overall validity of results. The practical utility of the BASC‐PRS is further supported in light of expanding roles for school psychologists in the assessment and treatment of children with health problems. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 145–154, 2003.
Comparative properties of a three‐dimensional model of Plasmodium falciparum ornithine decarboxylase
Authors: Birkholtz L. , Joubert F. , Neitz A.W.H. , Louw A.I. 
Published: January 2003

AbstractThe ornithine decarboxylase (ODC) component of the bifunctional S‐adenosylmethionine decarboxylase/ornithine decarboxylase enzyme (PfAdoMetDC‐ODC) of Plasmodium falciparum was modeled on the crystal structure of the Trypanosoma brucei enzyme. The homology model predicts a doughnut‐shaped active homodimer that associates in a head‐to‐tail manner. The monomers contain two distinct domains, an N‐terminal α/β‐barrel and a C‐terminal modified Greek‐key domain. These domains are structurally conserved between eukaryotic ODC enzymes and are preserved in distant analogs such as alanine racemase and triosephosphate isomerase‐like proteins. Superimposition of the PfODC model on the crystal structure of the human enzyme indicates a significant degree of deviation in the carbon α‐backbone of the solvent accessible loops. The surface locality of the ab initio modeled 38 amino acid parasite‐specific insert suggests a role in the stabilization of the large bifunctional protein complex. The active site pockets of PfODC at the interface between the monomers appear to be conserved regarding the binding sites of the cofactor and substrate, but each contains five additional malaria‐specific residues. The predicted PfODC homology model is consistent with mutagenesis results and biochemical studies concerning the active site residues and areas involved in stabilizing the dimeric form of the protein. Two competitive inhibitors of PfODC could be shown to interact with several parasite‐specific residues in comparison with their interaction with the human ODC. The PfODC homology model contributes toward a structure‐based approach for the design of novel malaria‐specific inhibitors. Proteins 2003;50:464–473. © 2003 Wiley‐Liss, Inc.
Effect of alcohol extract of Achyranthes aspera Linn. on acute and subacute inflammation
Authors: Vetrichelvan T. , Jegadeesan M. 
Published: January 2003

AbstractThe antiinflammatory activity of an alcohol extract of Achyranthes aspera was tested on carrageenin‐induced hind paw oedema and cotton pellet granuloma models in albino male rats. The paw volume was measured plethysmometrically at 0, 1, 2, 3, 4 and 5 h. In the subacute model cotton pellet granuloma was produced by implantation of 50 ± 1 mg sterile cotton in the axilla under ether anaesthesia. The animals were fed with an alcohol extract at various dose levels (125, 250, 375 and 500 mg/kg). Diclofenac sodium was used as a standard drug. The alcohol extract (375 and 500 mg/kg) showed the maximum inhibition of oedema of 65.38% and 72.37% at the end of 3 h with carrageenin‐induced rat paw oedema, respectively. Using a chronic test, the extract exhibited a 40.03% and 45.32% reduction in granuloma weight. Copyright © 2003 John Wiley & Sons, Ltd.
Prevention of diet‐induced type 2 diabetes in the C57BL/6J mouse model by an antidiabetic herbal formula
Authors: Huo Yushu , Winters Wendell D. , Yao Da‐lin 
Published: January 2003

AbstractSignificant positive effects of an antidiabetes herbal formula (ADHF) on the prevention of progressive diet‐induced type 2 diabetes (NIDDM) in the well recognized C57BL/6J mouse model were demonstrated. The results of the present studies confirm that C57BL/6J mice, through a genetic predisposition, developed NIDDM‐like symptoms on a regular schedule when fed solely on a diabetes induction diet containing high fat, high simple carbohydrate and low fibre. Blood glucose levels consistent with type 2 diabetes were detected after 8 weeks on this induction diet. In contrast, no members of the prevention study groups of C57BL/6J mice, which had ADHF mixed into their diabetes induction diet, developed progressive evidence of NIDDM‐like symptoms. Specific parameters observed to be significantly reduced in mice in the prevention diet groups fed ADHF mixed into the diabetes induction diet compared with the diabetes positive control groups fed diabetes induction diet only were clinical signs, blood glucose and serum insulin levels, insulin resistance and histopathological changes in major organs. This is the first report to our knowledge to show in vivo evidence for the successful prevention of progressive NIDDM‐like symptoms by the addition of an anti‐diabetes herbal formula to a effective diabetes induction diet. Copyright © 2003 John Wiley & Sons, Ltd.
Biological activities of synthetic saponins and cardiac glycosides
Authors: Takechi Masayuki , Doi Kyoko , Wakayama Yoshiki 
Published: January 2003

AbstractComparisons of the biological activities of diosgenyl (DIO) β‐D‐xylopyranosyl‐ (1 → 2)‐α‐D‐glucopyranoside (2DXα) and β‐D‐glucopyranosyl‐ (1 → 3)‐β‐D‐glucopyranoside (3GLβ) or methyl glycyrrhetinate (GAM) 2DXα and 3GLβ with those of the other DIO‐ or GAM‐ glycosides confirmed our assumption that both haemolytic and antifungal activities of DIO‐glycosides (steroid saponins) generally parallel each other, while almost all haemolytic GAM‐glycosides (triterpenoid saponins) have no antifungal activity. By comparisons of digitoxigenyl (DIG) 2DXα, β‐D‐xylopyranosyl‐ (1 → 2)‐β‐D‐glucopyranoside (2DXβ) and 3GLβ with the other DIG‐glycosides, the previous supposition on DIG‐diglycosides (cardiac diglycosides) has been developed into the assumption that those having a (1 → 4), (1 → 3) or (1 → 2)β sugar linkage show stronger anti‐ATPase and antiviral activities than those with a (1 → 6) or (1 → 2)α linkage. Copyright © 2003 John Wiley & Sons, Ltd.
The effect of a water extract and anthocyanins of hibiscus sabdariffa L. on paracetamol‐induced hepatoxicity in rats
Authors: Ali B. H. , Mousa H. M. , El‐Mougy S. 
Published: January 2003

AbstractWe investigated the effect of the water extract of the dried flowers of Hibiscus sabdariffa L. and Hibiscus anthocyanins (HAs) (which are a group of natural pigments occurring in the dried calyx of H. sabdariffa) on paracetamol‐induced hepatotoxicity in rats. The water extract was given in lieu of drinking water for 2, 3 or 4 consecutive weeks, and the HAs were given orally at doses of 50, 100 and 200 mg/Kg for five consecutive days. Paracetamol was given orally at a dose of 700 mg/Kg to induce hepatotoxicity at the end of the water extract and HAs treatments. Six hours thereafter the rats were killed and their liver function evaluated biochemically and histologically. Given for 4 weeks (but not for 2 or 3 weeks) the extract significantly improved some of the liver function tests evaluated, but did not alter the histology of the paracetamol‐treated rats or the pentobarbitone‐induced sleeping time. At a dose of 200 mg/Kg, the hepatic histology and the biochemical indices of liver damage were restored to normal. Lower does were ineffective. Pending more evaluation for safety and efficacy, the HAs can potentially be used in mitigating paracetamol‐induced hepatotoxicity. Copyright © 2003 John Wiley & Sons, Ltd.
The comparative effect of novel Pelargonium essential oils and their corresponding hydrosols as antimicrobial agents in a model food system
Authors: Lis‐Balchin M. , Steyrl H. , Krenn E. 
Published: January 2003

AbstractEssential oils and their corresponding hydrosols, obtained after distillation of various scented Pelargonium (Geraniaceae) leaves were assessed for their antimicrobial activity in a model food system. Both the essential oils and hydrosols were used at 1000 ppm in broccoli soup, previously inoculated with Enterobacter aerogenes (at 105 cfu g−1) and Staphylococcus aureus (at 104 cfu g−1). The results showed a complete inhibition of S. aureus in the broccoli soup by the essential oils of ‘Sweet Mimosa’, ‘Mabel Grey’, P. graveolens, ‘Atomic Snowflake’, ‘Royal Oak’, ‘Attar of Roses’ and a lesser effect by ‘Chocolate Peppermint’ and ‘Clorinda’; the hydrosols, however, had a potentiating effect on the bacterial population in the food. Both extracts showed a complete inhibition of S. aureus in the Maximum Recovery Diluent (MRD). Antibacterial activity against E. aerogenes in the broccoli soup was generally very much reduced: only the essential oil of ‘Mabel Grey’ showed complete inhibition and virtually no reductions in colonies were seen with the other essential oils; the hydrosols again caused an increase in bacterial colonies. All the essential oils, bar Chocolate Peppermint showed complete inhibition of E. aerogenes in MRD, but the hydrosols showed no effect. The results strongly suggest that the residual hydrosols from distillation of these plant essential oils have no potential as antibacterial agents in foods, in contrast to most of the essential oils, which show potential against some micro‐organisms, but only in some food systems. The problem of food component interference and its possible management is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Downregulation of hepatitis B surface antigen expression in human hepatocellular carcinoma cell lines by HD‐03, a polyherbal formulation
Authors: Yeh S. F. , Gupta Monika , Sarma D. N. K. , Mitra S. K. 
Published: January 2003

AbstractHepatitis B virus is associated with chronic or acute liver diseases and with hepatocellular carcinoma. In the present study, we examined the activity of HD‐03, a polyherbal formulation, on two hepatitis B surface antigen (HBsAg) expressing human hepatocellular carcinoma cell lines, PLC/PRF/5 and HepG2/A2. We observed that HD‐03 downregulates HBsAg expression from these cell lines. Our studies have also shown that this effect is neither due to cytotoxicity on the cell lines nor due to blockade of the release of the antigen from the cells nor due to binding of the substance with the antigen. The possible mode of its antiviral activity is explained. Copyright © 2003 John Wiley & Sons, Ltd.