bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and evaluation of photocrosslinkable chitosan as a drug delivery matrix
Authors: Jameela S.R. , Lakshmi S. , James Nirmala R. , Jayakrishnan A. 
Published: October 2002

AbstractEpichlorohydrin (1‐chloro‐2,3‐epoxypropane) was reacted with sodium azide in the presence of a phase transfer catalyst to obtain 1‐chloro‐2‐hydroxy‐3‐azidopropane, which was further coupled onto chitosan to prepare a photocrosslinkable derivative of the biopolymer. Elemental analysis and infrared (IR) spectroscopy confirmed the incorporation of azide groups onto chitosan. Films were cast from an aqueous acetic acid solution of azidated chitosan containing a model drug, such as theophylline. Irradiation of the film with ultraviolet (UV) light led to crosslinking of the drug incorporated film. IR spectra indicated complete surface crosslinking within 2 h of irradiation. Release of theophylline from uncrosslinked and crosslinked films was examined in simulated gastric and intestinal fluids without enzymes at 37 °C. The release of the drug from the crosslinked films was slower than the release from uncrosslinked films. Although the system is far from being optimized to obtain sustained release of a pharmacologically active agent for long periods, the data obtained indicate the possibility of developing photocrosslinkable matrices of biopolymers, such as chitosan, for sustained drug delivery with many advantages over chemical crosslinking. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1873–1877, 2002
Water‐vapor‐permeable polyurethane resin
Authors: Chwang C. P. , Lee S. N. , Yeh J. T. , Chen C. Y. , Chao D. Y. 
Published: October 2002

AbstractThe reaction of methylene diphenylene diisocyanate with ethylene glycol, dimethyl dimethoxysilane, dimethyl diethyloxysilene, and other additives in the presence of N,N‐dimethylformamide and toluene to form the structure of water‐vapor‐permeable polyurethane (PU) resin was proven with Fourier transform infrared spectra. Experimental results clearly showed that the amount of oxygen that permeated the film made with the PU resin increased with an increase in the concentration of ethylene glycol, diethylene glycol, or triethylene glycol. This was due to an increased number of hydrophilic groups attached to the backbone of the PU resin molecules. These hydrophilic groups, because of the intermolecular interactions between PU resin molecules, made PU resin molecules form an expanded conformation with large porosities. Interestingly, the water vapor permeability of the PU resin appeared to increase with an increasing concentration of ethylene glycol, dimethyl dimethoxysilane, or dimethyl diethoxysilane but not to increase with an increasing concentration of diethylene glycol, triethylene glycol, or poly(ethylene glycol) with dimethyl dimethoxysilane. The former was due to intermolecular interactions resulting in an expanded conformation with large porosities, but the latter was due to intramolecular interactions resulting in a compact conformation or a micellelike structure with small porosities. Therefore, the water vapor permeability of the former increased, but the latter remained unchanged or decreased. Our experimental results suggest that the use of poly(ethylene glycol) 400, ethylene glycol, dimethyl dimethoxysilane, and other strong hydrophilic compound in the preparation of modified PU resins substantially raises the amount of water vapor diffusing into films made with these resins. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2002–2010, 2002
A polyacrylic acid as a carrier for immobilization of penicillin acylase
Authors: Li Yuanxun , Su Xinqing , Ye Qingling 
Published: October 2002

AbstractA copolymer of acrylic acid with divinylbenzene was synthesized by suspension polymerization. This polymer is an effective carrier. Penicillin acylase was immobilized on this carrier to convert benzylpenicillin to 6‐aminopenicillanic acid, which may be employed in the manufacture of semisynthetic penicillins. Factors that affect the activity of immobilized penicillin acrylase, such as temperature, pH, and amount of native enzyme, were studied. Under suitable conditions, the activity and activity recovery of the immobilized enzyme were 3100 U/g (dry carrier, p‐dimethylaminobenzaldehyde method) and 59.7%, respectively. The immobilized penicillin acylase shows a remarkable increase in stability. At 40°C and pH 8.0 the value of the kinetic Michaelis–Menten constant (Km) of the immobilized enzyme is 2.8 × 10−3 mol/L, and the value of activation energy of enzyme catalysis is 71.5 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2067–2069, 2002
Stability constants of polymer‐bound iminodiacetate‐type chelating agents with some transition‐metal ions
Authors: Chen Chuh‐Yean , Chen Chuh‐Yung 
Published: October 2002

AbstractA chelating vinyl monomer, glycidyl methacrylate (GMA)–iminodiacetic acid (IDA), was formed by the reaction between GMA and IDA. Three polymeric chelating agents, PGMA–IDA, PGMA–IDA‐co‐methyl acrylate (MA), and PGMA–IDA‐co‐acrylamide (AAm), were also synthesized. Acid dissociation constants and stability constants of these chelating agents with Ni(II), Zn(II), and Co(II) were determined by means of potentiometric titration and ultraviolet–visible spectrophotometry, respectively. The values of Ka1 and Ka2 of all the polymeric chelating agents were smaller than those of GMA–IDA. The stability constants of all the polymeric chelating agents were larger than those of GMA–IDA. Increasing the MA content within PGMA–IDA‐co‐MA affected the stability constant only slightly. A proper molar ratio of AAm in PGMA–IDA‐co‐AAm, stability constants was 30–60 times greater than that of GMA–IDA. However, as the molar content of AAm increased, the stability constant of PGMA–IDA‐co‐AAm decreased. The results obtained in the polymer system are explained in terms of the polymer's stereo and entanglement structure, the neighboring effect, and the hydrophobic/hydrophilic nature of MA or AAm. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1986–1994, 2002
Rats can discriminate illuminance, but not magnetic fields, as a stimulus for learning a two‐choice discrimination
Authors: Creim J.A. , Lovely R.H. , Miller D.L. , Anderson L.E. 
Published: October 2002

AbstractIn each of the two experiments, nine rats were trained for 64 trials (eight trials per day) to determine if they could acquire a two‐choice discrimination based on a specified discriminative stimulus (SD). In one experiment, the SD was a change in ambient illumination, while in the second experiment the SD was a change in the combination of sinusoidal 60 Hz and static magnetic field (MF) and any cues attendant to energizing the coils that produced the MF exposure. The rats that had a change in illuminance as the SD learned the two‐choice task easily, P < .001, whereas the rats having a change in MFs as the SD did not. Bioelectromagnetics 23:545–549, 2002. © 2002 Wiley‐Liss, Inc.
A null space algorithm for mixed finite‐element approximations of Darcy's equation
Authors: Arioli Mario , Manzini Gianmarco 
Published: October 2002

AbstractA null space algorithm is considered to solve the augmented system produced by the mixed finite‐element approximation of Darcy's Law. The method is based on the combination of an orthogonal factorization technique for sparse matrices with an iterative Krylov solver. The computational efficiency of the method relies on a suitable stopping criterion for the iterative solver. We experimentally investigate its performance on a realistic set of selected application problems. Copyright © 2002 John Wiley & Sons, Ltd.
Nonlinear dynamics of EEG in Alzheimer's disease
Authors: Jeong Jaeseung 
Published: October 2002

AbstractNonlinear dynamical analysis has been widely applied to a variety of physiological data for last two decades. One of its major contributions is to the electroencephalogram (EEG) in Alzheimer's disease (AD). A number of studies using nonlinear dynamical methods have shown the globally decreased complexity of EEG patterns in AD patients. A prominent decrease in information transmission among cortical areas quantified by information‐theoretic measures like mutual information is also found. These findings indicate decreased nonlinear processes underlying the EEG in AD. This review article focuses on nonlinear EEG abnormalities in AD patients obtained from nonlinear methods and their clinical implications. We suggest that nonlinear dynamical analysis may contribute to a deeper understanding of the neuropathological mechanism of AD in ways that are not possible by conventional spectral analysis. Drug Dev. Res. 56:57–66, 2002. © 2002 Wiley‐Liss, Inc.
Clinical significance of interleukin‐6 and interleukin‐6 receptor expressions in oral squamous cell carcinoma
Authors: Wang Yi‐Fen , Chang Shyue‐Yih , Tai Shyh‐Kuan , Li Wing‐Yin , Wang Liang‐Shun 
Published: October 2002

AbstractBackgroundRecent studies showed that interleukin‐6 (IL‐6) played a role in tumor development. However, available information about the prognostic significance of IL‐6 and IL‐6 receptors (IL‐6R) for oral squamous cell carcinoma (OSCC) is limited.MethodsEighty‐six patients with OSCC were enrolled. Immunohistochemical staining was used to determine IL‐6R expression and in‐situ hybridization for IL‐6 mRNA transcripts in surgical specimens. Clinicopathologic correlation was evaluated by chi‐square test and survival by log rank test.ResultsExpression rates of IL‐6R and IL‐6 mRNA transcripts in tumor specimens were 73.3% and 54.7%, much higher than those in nontumor mucosa (p < .001). IL‐6R overexpression was associated with larger tumors and more advanced histologic grade (p < .05). The presence of IL‐6 mRNA transcripts was inversely correlated with distant metastasis, lymph node involvement, and second primary SCC (p < .05) and predicted better survival (p = .007).ConclusionsIL‐6‐IL‐6R coexpression was rather high in OSCC, and IL‐6 mRNA transcript expression might influence patient survival. The biologic role of IL‐6‐IL‐6R coexpression in OSCC needs additional investigation. © 2002 Wiley Periodicals, Inc. Head Neck 24: 850–858, 2002
Role of Helicobacter pylori infection among offspring or siblings of gastric cancer patients
Authors: Chang Young‐Woon , Han Yo‐Seob , Lee Dong‐Keun , Kim Hyo‐Jong , Lim Hyun‐Seok , Moon Jeong‐Seop , Dong Seok‐Ho , Kim Byung‐Ho , Lee Joung‐Il , Chang Rin 
Published: October 2002

AbstractA positive family history is an increased risk factor for gastric cancer within family members, and one of the possible causes of this is the intrafamilial clustering of Helicobacter pylori infection. Our study examined the prevalence of H. pylori infection, serum antibodies to CagA and VacA and atrophic gastritis and/or intestinal metaplasia in the offspring or siblings of gastric cancer patients. A total of 726 subjects included 300 relatives of 300 separate gastric cancer patients and 426 controls. All subjects underwent upper gastrointestinal endoscopic examination with a rapid urease test. Blood samples were obtained to test for the presence of serum antibodies to the CagA and VacA proteins of H. pylori. The prevalence of H. pylori infection was higher in relatives of cancer patients (75.3%) than in controls (60.1%), and the adjusted odds ratio was 2.1 (95% CI 1.5–2.9). When either siblings or 2 or more family members were gastric cancer patients, the prevalence of H. pylori infection was much higher compared to the prevalence in controls. There was no specific relationship between CagA and VacA, and H. pylori infection. Atrophic gastritis and/or intestinal metaplasia were more frequently found in H. pylori‐infected relatives of cancer patients (26.1%) than in H. pylori‐infected controls (12.9%). These results strongly support a role for H. pylori infection in familial aggregation of gastric cancer. The prophylactic eradication of H. pylori infection in the offspring or siblings of gastric cancer patients may be clinically beneficial. © 2002 Wiley‐Liss, Inc.
Micropattern formation of apatite by combination of a biomimetic process and transcription of resist pattern
Authors: Ozawa Naoshi , Yao Takeshi 
Published: October 2002

AbstractTwo kinds of methods combining a biomimetic process and transcription of resist pattern were conducted to form an apatite micropattern. For method 1, apatite nuclei were formed on a resist pattern printed substrate by setting it in contact with CaO‐SiO2‐based glass in a simulated body fluid (SBF) with inorganic ion concentrations nearly equal to those of human blood plasma. Next, apatite was grown from the nuclei by soaking the substrate in an aqueous solution with ion concentrations 1.5 times those of SBF (1.5 SBF). Then, the resist material was dissolved off by organic solvent with the apatite just formed on it. Apatite micropattern transcribing the resist pattern was obtained. For method 2, apatite nuclei were formed on a resist pattern printed substrate by setting it in contact with CaO‐SiO2‐based glass in SBF. Next, the resist material was dissolved off with the apatite nuclei just formed on it. Then, the substrate was soaked in 1.5 SBF to grow the remaining nuclei and an apatite micropattern transcribing the resist pattern was obtained. For both methods, minute apatite patterns with various shapes as straight lines, bending lines, and blocks were clearly formed. The minimum line width of the obtained pattern was 2 μm. These methods are promising for producing multifunctional materials with bioaffinity. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 579–586, 2002
Surface engineering of poly(D,L‐lactic acid) by entrapment of chitosan‐based derivatives for the promotion of chondrogenesis
Authors: Zhu Huiguang , Ji Jian , Lin Rongyi , Gao Changyou , Feng Linxian , Shen Jiacong 
Published: October 2002

AbstractChitosan and chitosan–amino acid derivatives were explored to engineer poly(D,L‐lactic acid) (PDL‐LA) as an extracellular matrix‐like surface to promote cell adhesion and growth. Four kinds of chitosan–amino acid derivatives were prepared to mimic the carbohydrate moieties of cell matrix glycoprotein. The chitosan–amino acid derivatives were characterized by using Fourier transform infrared and ultraviolet spectra. The amino acid content on chitosan–amino acid derivatives was determined by using a ninhydrin‐ultraviolet method. A new strategy, entrapment, was therefore used to modify the PDL‐LA membrane with chitosan and chitosan–amino acid derivatives. The results of X‐ray photoelectron spectroscopy, attenuated total reflectance–Fourier transform infrared, and contact angle confirmed that a stable thin film of chitosan and its derivatives can be entrapped on the surface of the PDL‐LA membrane. From the results of chondrocyte cytocompatibility, MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide] assays, and cell morphology, the chitosan–amino acid derivative modified PDL‐LA membranes were shown to promote chondrogenesis. The novel surface treatment method combines the good mechanical property of PDL‐LA with the good cytocompatibility of chitosan derivatives, which may have potential for tissue engineering. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 532–539, 2002
Biocompatibility of dense hydroxyapatite prepared using an SPS process
Authors: Nakahira A. , Tamai M. , Aritani H. , Nakamura S. , Yamashita K. 
Published: October 2002

AbstractIn the present study, the preparation of dense hydroxyapatite (HAp) materials at relative low temperatures using a spark plasma sintering was carried out. The bioactivity of HAp samples prepared by a spark plasma sintering method was investigated by in vitro tests and compared with HAp obtained by a conventional hot‐pressing method. No growth of bone‐like HAp crystals on surface of HAp sintered by a conventional hot‐pressing method at 1200°C was observed after immersion in a simulated body fluid (SBF) for 2 days. However, many large bone‐like HAp crystals were observed on the surface of HAp samples prepared by a spark plasma sintering at 1200°C after 2 days in the SBF immersion test. Especially, the negatively charged surface of the HAp samples prepared by spark plasma sintering was covered with larger HAp crystals compared with the positively charged surface. The electric poling of HAp was measured using a thermally simulated current technique. This rapid growth of bone‐like HAp crystals of the HAp samples made by spark plasma sintering was believed to be related with the OH− and/or Ca ion deficiency at the grain boundaries of the HAp matrix grains as well as a small electric poling effect resulting during the spark plasma sintering process. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 550–557, 2002
Dynamic structural changes of synaptic contacts in the visual system of insects
Authors: Pyza Elzbieta 
Published: October 2002

AbstractThe visual system of insects provides an excellent model to study processes of transduction and transmission of photic information, synaptogenesis, synaptic plasticity, and wiring between photoreceptors and their visual interneurons in the optic lobe. This review describes synaptic contacts between photoreceptors and other neurons in the visual system of insects, especially in the fly's first optic neuropile (the lamina), and summarizes changes observed in the synapses of visual cells that have been reported both in phylogeny and ontogeny, and also examples of synaptic plasticity in adult insects that have been evoked by intrinsic and extrinsic factors. Plasticity observed in synapses of the insect's visual system seems to exemplify not only synaptic contacts in insects but, given that similar examples of plasticity have been found in other animal groups, may also be a general phenomenon in the nervous system. Microsc. Res. Tech. 58:335–344, 2002. © 2002 Wiley‐Liss, Inc.
Feline immunodeficiency virus vectors. Gene transfer to mouse retina following intravitreal injection
Authors: Derksen Todd A. , Sauter Sybille L. , Davidson Beverly L. 
Published: October 2002

AbstractBackgroundTransduction of the murine retinal pigmented epithelium (RPE) with adenovirus vectors requires technically difficult and invasive subretinal injections. This study tested the hypothesis that recombinant vectors based on feline immunodeficiency virus (FIV) could access the retina following intravitreal injection.MethodsFIV vectors expressing E. coli β‐galactosidase (FIVβgal) were injected alone, or in combination with adenovirus vectors expressing eGFP, into the vitreous of normal mice and eyes evaluated for transgene expression. In further studies, the utility of FIV‐mediated gene transfer to correct lysosomal storage defects in the anterior and posterior chambers of eyes was tested using recombinant FIV vectors expressing β‐glucuronidase. FIVβgluc vectors were injected into β‐glucuronidase‐deficient mice, an animal model of mucopolysacharridoses type VII.ResultsThe results of this study show that similar to adenovirus, both corneal endothelium and cells of the iris could be transduced following intravitreal injection of FIVβgal. However, in contrast to adenovirus, intravitreal injection of FIVβgal also resulted in transduction of the RPE. Immunohistochemistry following an intravitreal injection of an AdeGFP (adenovirus expressing green fluorescent protein) and FIVβgal mixture confirmed that both viruses mediated transduction of corneal endothelium and cells of the iris, while only FIVβgal transduced cells in the retina. Using the β‐glucuronidase‐deficient mouse, the therapeutic efficacy of intravitreal injection of FIVβgluc (FIV expressing β‐glucuronidase) was tested. Intravitreal injection of FIVβgluc to the eyes of β‐glucuronidase‐deficient mice resulted in rapid reduction (within 2 weeks) of the lysosomal storage defect within the RPE, corneal endothelium, and the non‐pigmented epithelium of the ciliary process. Transgene expression and correction of the lysosomal storage defect remained for at least 12 weeks, the latest time point tested.ConclusionThese studies demonstrate that intravitreal injection of FIV‐based vectors can mediate efficient and lasting transduction of cells in the cornea, iris, and retina. Copyright © 2002 John Wiley & Sons, Ltd.
Changing molecular epidemiology of hepatitis C virus infection in Northeast Italy
Authors: Dal Molin Gianna , Ansaldi Filippo , Biagi Claudia , D'Agaro Pierlanfranco , Comar Manola , Crocè Lory , Tiribelli Claudio , Campello Cesare 
Published: October 2002

AbstractTo assess HCV genotype distribution and its determinants, 318 consecutive HCV RNA positive patients were examined. Subtype 1b infection was the most prevalent (35.5%), followed by subtype 1a (22%), 3a (21.4%) and 2 genotype (21.3%). Subtypes 1a, 1b and 3a had a comparable prevalence (30–35%) in the 0–15‐, 16–30‐ and 31–45‐year age groups. In subjects older than 45 years, genotype 2 prevalence increased, whereas subtype 1a and 3a infections decreased markedly. In this age group types 1b and 2 accounted for a prevalence of more than 90% in a comparable proportion. Genotype prevalence rates according to different risk factors were different statistically (P < 0.001): subtype 1a and 3a infections were predominant in injection drug users (42.9% and 37.7%, respectively), whereas community acquired infections and infections in patients with a history of transfusion were caused mainly by subtype 1b (38.5% and 66.6%, respectively). Logistic regression showed that age and injection drug use are independent determinants of genotype distribution. J. Med. Virol. 68:352–356, 2002. © 2002 Wiley‐Liss, Inc.
The confounding role of personality and trait affectivity in the relationship between job and life satisfaction
Authors: Heller Daniel , Judge Timothy A. , Watson David 
Published: October 2002

AbstractPrevious research has demonstrated a strong positive relationship between job and life satisfaction. Traditionally, this relationship has been explained in terms of a spillover model, wherein job experiences spill over onto life, and vice versa. This study directly tests a different explanation for this relationship: personality traits that influence both job and life satisfaction. In a longitudinal test with multisource data, three typologies, which were shown by past research to be linked to both job and life satisfaction, were examined: Big Five, positive and negative affectivity, and core self‐evaluations. One hundred and fifty‐three university employees working in a diverse set of occupations were surveyed twice, with a six month time interval; the first survey also included a second questionnaire to be completed by a ‘significant other.’ Analyses of concurrent and prospective zero‐order and partial correlations, as well as structural equation modeling, supported the hypothesized confounding role of all three typologies, especially core self‐evaluations. Though controlling for personality reduced the magnitude of the job–life satisfaction relationship, it did not entirely eliminate it. Overall, the results suggest the presence of both dispositional and environmental factors in job and life satisfaction. Finally, implications for organizational practice and theory development are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Fluorescence probes based on 9‐acridyl derivatives of aromatic amines for monitoring free‐radical polymerization
Authors: Bajorek Agnieszka , Ciepluch Marcin , Pączkowski Jerzy 
Published: October 2002

AbstractThe series of 9‐acridyl derivatives of aromatic amines have been investigated as fluorescent probes for monitoring the progress of free‐radical polymerization. This study on the changes in the fluorescence intensity and spectroscopic shift of specific compounds was carried out during thermally initiated polymerization of methyl methacrylate and photoinitiated polymerization of 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol triacrylate‐1‐methyl‐2‐pyrrolidonone mixture. The purpose of this investigation was to find a relationship between the changes in the shape and intensity of fluorescent probes and the degree of monomer conversion into a polymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3481–3488, 2002