bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hybrid pancreatic tissue substitute consisting of recombinant insulin‐secreting cells and glucose‐responsive material
Authors: Cheng S‐Y. , Gross J. , Sambanis A. 
Published: August 2004

AbstractInsulin‐dependent diabetes is a serious pathological condition, currently treated by blood glucose monitoring and daily insulin injections, which, however, do not prevent long‐term complications. A tissue‐engineered pancreatic substitute has the potential to provide a more physiologic, less invasive, and potentially less costly treatment of the disease. A major issue in developing such a substitute is the cells being used. Nonpancreatic cells, retrieved from the same patient and genetically engineered to secrete insulin constitutively or with some glucose responsiveness, offer the significant advantages of being immune‐acceptable and relaxing the tissue availability limitations, which exist with islets from cadaveric donors. These cells, however, do not have insulin secretion dynamics appropriate for restoration of euglycemia in higher animals and, eventually, humans. In this study, we present the concept of a hybrid pancreatic substitute consisting of such cells sequestered in a material exhibiting glucose‐dependent changes of its permeability to insulin. A Concanavalin A‐glycogen material sandwiched between two polycarbonate membranes and exhibiting glucose‐dependent sol‐gel transformations was used. Rates of insulin transport through this material in gel and sol forms were characterized for both FITC‐labeled insulin in solution and insulin secreted by βTC3 mouse insulinoma cells. Effective diffusivities through sol were found to be up to 3.5‐fold higher than through the gel state of the material. A mathematical model of a hybrid construct was formulated and analyzed to simulate the secretory behavior in response to step ups and downs in the surrounding glucose concentration. The experimental and modeling studies indicate that a hybrid pancreatic substitute consisting of constitutively secreting cells and glucose‐responsive material has the potential to provide a more physiologic regulation of insulin release than the cells by themselves or in an inert material. © 2004 Wiley Periodicals, Inc.
Modeling hexavalent chromium removal in a Bacillus sp. fixed‐film bioreactor
Authors: Nkhalambayausi‐Chirwa Evans M. , Wang Yi‐Tin 
Published: August 2004

AbstractA one‐dimensional diffusion‐reaction model was developed to simulate Cr(VI) reduction in a Bacillus sp. pure culture biofilm reactor with glucose as a sole supplied carbon and energy source. Substrate utilization and Cr(VI) reduction in the biofilm was best represented by a system of (second‐order) partial differential equations (PDEs). The PDE system was solved by the (fourth‐order) Runge‐Kutta method adjusted for mass transport resistance using the (second‐order) Crank‐Nicholson and Backward Euler finite difference methods. A heuristic procedure (genetic search algorithm) was used to find global optimum values of Cr(VI) reduction and substrate utilization rate kinetic parameters. The fixed‐film bioreactor system yielded higher values of the maximum specific Cr(VI) reduction rate coefficient and Cr(VI) reduction capacity (kmc = 0.062 1/h, and Rc = 0.13 mg/mg, respectively) than previously determined in batch reactors (kmc = 0.022 1/h and Rc = 0.012 mg/mg). The model predicted effluent Cr(VI) concentration well with 98.9% confidence (σ = 2.37 mg2/L2, N = 119) and effluent glucose with 96.4 % confidence (σ = 5402 mg2/L2, N = 121, w = 100) over a wide range of Cr(VI) loadings (10–498 mg Cr(VI)/L/d). © 2004 Wiley Periodicals, Inc.
An impedance study on admiralty brass dezincification originated by microbiologically influenced corrosion
Authors: Ibars J.R. , Polo J.L. , Moreno D.A. , Ranninger C. , Bastidas J.M. 
Published: August 2004

AbstractIn this article we describe a field study of biofouling and microbiologically influenced corrosion (MIC) of admiralty brass heat exchanger tubes in contact with running fresh water on the river Tagus close to Almaraz nuclear power plant in Spain. Dezincification originated by biofouling and MIC was studied using impedance, polarization resistance, gravimetric, scanning electron microscopy (SEM), and X‐ray diffraction (XRD) measurements. Close correlation was observed between the biofilms formed and the corrosion process (dezincification) using the different experimental techniques. Impedance data showed a capacitive behavior including two time constants. Kramers‐Kronig (KK) transforms were used to validate impedance data. The admiralty tubes' impedance data satisfied the KK relations. © 2004 Wiley Periodicals, Inc.
In vitroeffects of high glucose concentrations on membrane protein oxidation, G‐actin and deformability of human erythrocytes
Authors: Resmi Halil , Akhunlar Hülya , Temiz Artmann Ayşegül , Güner Gül 
Published: August 2004

AbstractThe object of this study was to examine the effect of elevatedin vitroglucose concentrations on protein modification and functional changes in human erythrocytes. Groups were exposed to 5–45 mMglucose concentrations. The time effect of any changes was also evaluated. In erythrocyte ghosts, protein glycation and oxidation were evaluated using spectrophotometric methods. G‐actin was measured by a DNase I inhibition assay in cell lysates. Erythrocyte deformability was assessed using a cell transit analyser. At 24 h, a significant protein oxidation (at 25 and 45 mMglucose;p < 0.05), and G‐actin increase was observed for all concentrations (p < 0.05). At 48 h, a significant increase in glycation (25 and 45 mMglucose;p < 0.05), protein oxidation (p < 0.05), and G‐actin (p < 0.05) was observed in all groups. A significant positive correlation was observed between glucose /protein oxidation, glucose/G‐actin and protein oxidation/G‐actin at 24 and 48 h. Our findings show that the oxidative effect of glucose on erythrocytes depends on concentration and incubation time. We also present the first evidence of increased G‐actin in human erythrocytes exposed to high glucose concentrations as a diabetes model. Copyright © 2004 John Wiley & Sons, Ltd.
Protective effects of melatonin against carbon tetrachloride‐induced hepatotoxicity in rats: a light microscopic and biochemical study
Authors: Kus Ilter , Ogeturk Murat , Oner Hakan , Sahin Semsettin , Yekeler Hayrettin , Sarsilmaz Mustafa 
Published: August 2004

AbstractThe aim of this study was to examine the protective effects of melatonin against CCl4‐induced hepatotoxicity in the rat. Twenty‐four male Wistar rats were divided into three groups. Group I was used as a control. Rats in group II were injected every other day with CCl4 for 1 month, whereas rats in group III were injected every other day with CCl4 and melatonin for 1 month. At the end of the experiment, all animals were killed by decapitation and blood samples were obtained. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total and conjugated bilirubin levels were determined. For histopathological evaluation, livers of all rats were removed and processed for light microscopy. All serum biochemical parameters were significantly higher in animals treated with CCl4 than in the controls. When rats injected with CCl4 were treated with melatonin, significantly reduced elevations in serum biochemical parameters were found. In liver sections of the CCl4‐injected group, necrosis, fibrosis, mononuclear cell infiltration, haemorrhage, fatty degeneration and formation of regenerative nodules were observed. Additionally, apoptotic figures, microvesicular steatosis and hydropic degeneration in hepatocytes were seen in this group. In contrast, the histopathological changes observed after administration of CCl4 were lost from rats treated with CCl4 and melatonin. Except for mild hydropic degeneration of the hepatocytes, a normal lobular appearance was seen in the livers of this group. The results of our study indicate that melatonin treatment prevents CCl4‐induced liver damage in rats. Copyright © 2004 John Wiley & Sons, Ltd.
Polarity Matching of Radical Trapping: High Yielding 3‐exo and 4‐exo Cyclizations
Authors: Gansäuer Andreas , Lauterbach Thorsten , Geich‐Gimbel Daniel 
Published: August 2004

AbstractA catalyzed synthesis of cyclopropanes and cyclobutanes via radical chemistry is described. The method that generally proceeds in high yields uses epoxides as radical precursors and titanocene(III) complexes as the electron transfer catalysts (see scheme). The key to the success of the transformation is constituted by the chemoselectivity of radical reduction. Electrophilic enol radicals generated through cyclization are reduced rapidly whereas their precursors, nucleophilic alkyl radicals, remain unaffected.
Expression of Fas ligand in retinoblastoma
Authors: Krishnakumar Subramanian , Kandalam Mallikarjuna , Mohan Adithi , Iyer Anita , Venkatesan Nalini , Biswas Jyotirmay , Shanmugam Mahesh Palanivelu 
Published: August 2004

AbstractBACKGROUNDThe importance of the Fas‐Fas ligand (FasL) mechanism for the immune evasion by tumors provided a strong rationale for the examination of FasL expression in retinoblastoma. In an earlier publication, the authors reported that invasive retinoblastomas decreased Fas expression. Because to the authors' knowledge there is not much information regarding the effect of FasL expression on retinoblastoma, the authors studied the expression of FasL in retinoblastoma and correlated it with invasiveness.METHODSThirty‐six archival retinoblastoma specimens were divided into 2 groups. Group A (n = 17) was comprised of specimens from tumors with no invasion and Group B (n = 19) was comprised of specimens from tumors with invasion of the choroid (focal, diffuse), optic nerve (laminar, postlaminar, surgical end), and orbit. Sections were immunostained with a monoclonal antibody to FasL and the immunoreactivity was assessed.RESULTSIn Group A, FasL was negative in 100% (17 of 17) of the tumor specimens. In Group B, FasL was expressed in 79% (15 of 19) of the tumor specimens (positive in 9 tumors and heterogeneous in 6 tumors). The difference in FasL expression between the two groups was significant (P < 0.001)CONCLUSIONSIncreased expression of FasL was observed in specimens taken from patients with aggressive tumors. Thus, Loss of Fas and gain of aberrant FasL expression were common features of malignant transformation. The data suggested that the Fas/FasL pathway is potentially immunosuppressive and may be involved in the escape of retinoblastoma cells from immune destruction. Cancer 2004. © 2004 American Cancer Society.
The superior prognostic value of humoral factors compared with molecular proliferation markers in renal cell carcinoma
Authors: Lehmann Jan , Retz Margitta , Nürnberg Nils , Schnöckel Uta , Raffenberg Uta , Krams Matthias , Kellner Udo , Siemer Stefan , Weichert‐Jacobsen Klaus , Stöckle Michael 
Published: August 2004

AbstractBACKGROUNDThe American Joint Committee on Cancer and the Union Internationale Contre le Cancer have acknowledged routine laboratory parameters, such as serum calcium, alkaline phosphatase, hemoglobin, and the erythrocyte sedimentation rate (ESR), as predictors of survival in patients with renal cell carcinoma. The predictive value of these parameters compared with proliferation markers, such as Ki‐67, proliferating cell nuclear antigen (PCNA), topoisomerase II‐α, and p100, has not been determined.METHODSForty‐eight consecutive patients who underwent nephrectomy for nonmetastatic renal cell carcinoma between 1990 and 1994 were observed up to 120 months postoperatively. Ten of 48 patients developed tumor progression 6–69 months after surgery. Routine preoperative laboratory parameters as well as tumor‐specific data were assessed. Findings were compared with tumor proliferation indices, which were obtained by immunohistochemical staining for nuclear antigens Ki‐67, PCNA, topoisomerase II‐α, and p100 in paraffin embedded tumor tissue.RESULTSUnivariate and multivariate statistical analyses demonstrated superiority of routine laboratory values compared with tumor proliferation indices in predicting progression‐free survival and disease‐specific death. The best predictor after tumor size and symptomatic presentation was ESR (P< 0.0001), with ESR values > 70 mm at 2 hours indicating a significantly poorer prognosis. Only the proliferation marker Ki‐67 reached univariate significance at a threshold of 7%.CONCLUSIONSRoutine laboratory parameters, such as alkaline phosphatase, lactate dehydrogenase, thrombocyte count, and especially ESR, provided superior long‐term prognostic information for patients with nonmetastatic renal cell carcinoma compared with the molecular tumor proliferation markers Ki‐67, PCNA, topoisomerase II‐α, and p100. Cancer 2004. © 2004 American Cancer Society.
Regulatory T‐cells in type 1 diabetes
Authors: Juedes Amy E. , von Herrath Matthias G. 
Published: August 2004

AbstractType 1 diabetes is a T‐cell‐mediated autoimmune disease, resulting in destruction of the insulin‐producing beta cells in the pancreas. Disease progression is thought to involve the action of T‐cells, particularly those producing Th1‐type cytokines. Given the complexity in understanding the precise etiology of autoimmune diseases, the diversity of autoantigens, and the variability that exists between individual patients, it might be very difficult to eliminate autoaggressive T‐cell responses without resorting to generalized means of immunosuppression. However, recent evidence shows that autoimmune processes are composed not only of autoaggressive T‐cell responses but also of autoreactive regulatory components. Enhancing regulatory T‐cell responses, therefore, has become an area of intense focus as a means of treating autoimmune diseases like type 1 diabetes. This review will concentrate on two different types of regulatory T‐cells, the naturally occurring (‘professional’) CD4+CD25+ T‐cells and antigen‐induced (‘adaptive’) CD4+ Th2‐like regulatory T‐cells. Copyright © 2004 John Wiley & Sons, Ltd.
Tol2 transposon‐mediated enhancer trap to identify developmentally regulated zebrafish genes in vivo
Authors: Parinov Serguei , Kondrichin Igor , Korzh Vladimir , Emelyanov Alexander 
Published: August 2004

AbstractWe have used the Tol2 transposable element to design and perform effective enhancer trapping in zebrafish. Modified transposon DNA and transposase RNA were delivered into zebrafish embryos by microinjection to produce heritable insertions in the zebrafish genome. The enhancer trap construct carries the EGFP gene controlled by a partial epithelial promoter from the keratin8 gene. Enhanced green fluorescent protein (EGFP) is used as a marker to select F1 transgenic fish and as a reporter to trap enhancers. We have isolated 28 transgenic lines that were derived from the 37 GFP‐positive F0 founders and displayed various specific EGFP expression patterns in addition to basal expression from the modified keratin 8 promoter. Analyses of expression by whole‐mount RNA in situ hybridization demonstrated that these patterns could recapitulate the expression of the tagged genes to a variable extent and, therefore, confirmed that our construct worked effectively as an enhancer trap. Transgenic offspring from the 37 F0 EGFP‐positive founders have been genetically analyzed up to the F2 generation. Flanking sequences from 65 separate transposon insertion sites were identified by thermal asymmetric interlaced polymerase chain reaction. Injection of the transposase RNA into transgenic embryos induced remobilization of genomic Tol2 copies producing novel insertions including some in the germ line. The approach has great potential for developmental and anatomical studies of teleosts. Developmental Dynamics 231:449–459, 2004. © 2004 Wiley‐Liss, Inc.
Development of a statistical approach to classifying treatment response in individual children with ADHD
Authors: Mollica Catherine M. , Maruff Paul , Vance Alasdair 
Published: August 2004

AbstractThe use of cognitive tests as measures of treatment response in individual children with ADHD has not been adequately evaluated or commonly applied by clinicians. This is most likely due to a lack of suitable assessment tasks as well as clinicians' limited awareness of the appropriate statistical techniques for analysing cognitive change in individuals. This study investigated the application of statistical decision rules to the cognitive and behavioural measures of individual children with ADHD in order to classify a significant, positive response to medication. The previously reported data of 14 children with ADHD (combined type; ADHD‐CT) were re‐analysed to investigate changes in function following a low‐ and high‐dose of stimulant medication (2.5 mg and 7.5 mg dexamphetamine, respectively). The performances of 14 age‐, gender‐ and IQ‐matched controls was also analysed to provide an estimate of the false‐positive classification rate. Overall, the decision rule yielded a high sensitivity and high specificity to treatment response. In the high‐dose condition, 71% of children with ADHD demonstrated improvements in both cognitive and behavioural function. This study demonstrates an evidence‐based approach to evaluating concurrent cognitive and behavioural improvement in individual children with ADHD following treatment with stimulant medication. Copyright © 2004 John Wiley & Sons, Ltd.
Expression of matrix metalloproteinase‐2 and ‐9 in exudates associated with polydimethyl siloxane and gelatin tubes implanted in mice
Authors: Xu Ping , Sefton Michael V. 
Published: August 2004

AbstractThe expression of matrix metalloproteinases (MMPs), MMP‐2 and ‐9, during the inflammatory response to two implanted biomaterials was determined. To illustrate this phenomenon, polydimethyl siloxane (PDMS), weakly crosslinked gelatin, and highly crosslinked gelatin tubes were implanted subcutaneously in mice for up to 3 weeks. Latent MMP‐2 (pro‐MMP‐2) was seen in exudates throughout the experimental period and did not show any apparent changes in time or among the three biomaterials. The expression of MMP‐9, however, showed a very different pattern. At days 4 and 8, the predominant form of MMP‐9 is pro‐MMP‐9 (the latent form) and its level is much higher for the PDMS tube than either of the gelatin tubes. The active form of MMP‐9, initially low, rose progressively over the 3‐week period and reached its peak at week 2 for PDMS and highly crosslinked gelatin and at week 3 for the more degradable, weakly crosslinked gelatin. Data from the histological and cytological analysis also showed that the PDMS tube induced a much stronger cellular response than gelatin tubes, although endotoxin contamination precludes a conclusion related to biomaterial effects. We concluded that MMP‐9 is a useful marker of the host inflammatory response to the implanted biomaterials and it may be useful in the assessment of biomaterial biocompatibility. Perhaps more importantly, the consequences of MMPs on matrix remodeling may become of concern in biomaterials used for tissue engineering. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 226–232, 2004
Synthesis and degradation of sodium iron phosphate glasses and their in vitro cell response
Authors: Parsons A. J. , Evans M. , Rudd C. D. , Scotchford C. A. 
Published: August 2004

AbstractThe degradation profiles of six sodium iron phosphate glass formulations have been investigated using simple dissolution trials in deionized water. The glasses were produced from the appropriate phosphate salts by melting at 1200°C in 5% Au/95% Pt crucibles. Dissolution rates varied from 0.2 gcm−2h−1 for the 1% Fe glass to essentially zero over the 6‐week test period for the 15% Fe and 20% Fe glasses. The overall degradation rate was found to vary according to the approximate relation: rate = 1.3e−0.79x gcm−2h−1, where x is the percentage iron content of the glass. Glasses with 10% or greater iron content were observed to maintain a constant density over the course of the tests and thus appeared to degrade from the surface and not the bulk. In vitro cell response tests were conducted on the glasses using macrophages and primary craniofacial osteoblasts. These tests were performed on the glasses with 10% or greater iron content because glasses with lower iron content degraded too quickly. Confocal microscopy revealed a rounded macrophage morphology and IL‐1β production was low, suggesting little macrophage activation. However, a significant level of peroxide production was observed. Osteoblasts were observed to attach to the glass surfaces and spread, exhibiting a similar cytosketetal organization to the cells on the Thermanox controls, with a high level of F‐actin organization. On balance, the 15% Fe glass performed slightly better than the 20% Fe glass in these assays. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 283–291, 2004
Effects of chitosan nonwoven membrane on periodontal healing of surgically created one‐wall intrabony defects in beagle dogs
Authors: Yeo Young‐Ju , Jeon Dong‐Won , Kim Chang‐Sung , Choi Seong‐Ho , Cho Kyoo‐Sung , Lee Yong‐Keun , Kim Chong‐Kwan 
Published: August 2004

AbstractThe purpose of this study was to investigate the periodontal regenerative effects of a chitosan nonwoven membrane applied to surgically created preclinical one‐wall intrabony defects in beagle dogs. One‐wall intrabony defects (4 × 4 × 4 mm) were surgically created bilaterally in the mandibular second and fourth premolars of six beagle dogs. The surgical control group received a flap operation only. The resorbable‐membrane (RM) group was treated with resorbable membrane. The chitosan‐nonwoven‐membrane (CNWM) group was treated with chitosan nonwoven membrane. The amount of junctional epithelium migration and the amount of connective tissue adhesion did not show any statistically significant differences among the groups. However, the amount of suprabony cementum regeneration, intrabony cementum regeneration, and alveolar bone regeneration showed significant differences (p < 0.05) between CNWM site group and control group. The results demonstrate the regenerative effects of the chitosan nonwoven membrane in one‐wall intrabony defects of beagle dogs. The chitosan nonwoven membrane has the potential to support the cementum and bone regeneration, possibly by providing the conditions needed for guided tissue regeneration in the one‐wall intrabony periodontal defects of beagle dogs. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 86–93, 2005
Evaluation of the effect of fluoride‐containing acetic acid on NiTi wires
Authors: Kwon Yong Hoon , Cho Ho‐Sung , Noh Dong‐Jin , Kim Hyung‐Il , Kim Kyo‐Han 
Published: August 2004

AbstractThe possibility of the formation of hydrofluoric acid by the reaction of fluoride with acetic acid seems natural in the oral cavity. The effect of an acidic fluoride solution on NiTi wires was investigated by testing microhardness and color changes on wires. For aesthetic reasons, the color change on wires was also evaluated. Wires were immersed in four different test solutions for 1 or 3 days. As‐received wires were used as a reference. After immersion for 3 days, the microhardness of the tested wires increased 1.8% to 10.4% compared to that of their as‐received state. Wires immersed in a higher NaF concentration, lower pH solution with longer immersion yielded a more corroded surface than those of the counter cases. Wires showed a different color after immersion. However, after 3 days in solutions of pH 4, wires showed an appreciable color change regardless of the products. In test solutions, 3M wires showed the highest volumetric and percentage (0.59 for 0.05%; 1.19 for 0.2% solution) weight loss and G&H wires showed the least volumetric and percentage (0.43 for 0.05%; 1.05 for 0.2% solution) weight loss among tested wires. In pH 6 solutions, wires lost weight and were under the detection limit of the testing machine. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 102–108, 2005