bluuebunny/crossref_metadata_2025 huggingface dataset:
Copper Complexation with Soluble and Surface Freshwaters Ligands
Authors: Botelho Cidália M. S. , Boaventura Rui A. R. , de L. S. Simões Gonçalves Maria
Published: December 2002

Speciation of copper has been done using samples collected at different times of the year (December 92 and October 93) and in three sites of a polluted river (Este River, Northern Portugal). Filtered samples and the suspended particulate matter were titrated with metal ion and the labile metal concentrations measured by anodic stripping voltammetry (DPASV). An extra peak in the Cu voltammograms has been noticed when titrating filtered samples and its origin was investigated. Results have suggested that the extra peak is due to copper(I) stabilized by ligands adsorbed on the mercury electrode and a model for the electrochemical mechanism is proposed. From titrations of the same samples with zinc, cadmium and lead it has been concluded that there are two types of organics in the river water: macromolecules and small molecules with DML≈DM with higher affinity for soft cations such as Cd(II) and Cu(I), that can be adsorbed on mercury electrode as anions.
Electrochemical Determination of Some Organic Pollutants Using Wall‐Jet Electrode
Authors: Manisankar P. , Selvanathan G. , Viswanathan S. , Gurumallesh Prabu H.
Published: December 2002

Determination of organic pollutants in trace level in a flow stream was developed using a wall‐jet electrode system and square‐wave stripping principles. Pesticides such as endosulfan, isoproturon and carbendazim, o‐chlorophenol and a benzidine bisazo dye, direct orange 8 were chosen for this study. The optimum conditions for adsorptive square‐wave stripping voltammetry were arrived at and the peak current responses of analyte were correlated over flow rate. Calibration plots were obtained by correlating the peak currents with concentration under optimum conditions. The best determination range, 1×10−4 to 4.0 mg/mL for endosulfan and 1×10−4 to 1.5 mg/mL for the remaining pollutants in a flowing stream was obtained with adsorptive square‐wave stripping technique.
Combined Voltammetric‐Potentiometric Sensor with Silver Solid Amalgam Link for Electroanalytical Measurements
Authors: Yosypchuk Bogdan , Novotný Ladislav
Published: December 2002

An arrangement of a combined voltammetric‐potentiometric sensor (CVPS) with a silver solid amalgam link (AgSAL) was designed, comprising a working electrode inserted into an internal solution of a proper depolarizer (e.g., 10 ppm Cu(II) in 0.2 M acetate buffer, 2% tartaric acid), which is separated from the analyzed solution by the AgSAL or other amalgam links. The preparation procedure of the AgSAL was described. The sensor has been successfully tested using solutions at various concentrations of Ag(I) and Hg(II) in various types of base electrolytes, exhibiting good selectivity with respect to Ag(I) or Hg(II) ions. The proportional voltammetric current concentration dependences ip−ln c were obtained and interpreted.
The Palaeogene flora of Hochstetten‐Dhaun (Nahe‐area, Rhineland‐Palatinate, SW‐Germany)
Authors: Uhl D. , Walther H. , Krings M.
Published: December 2002

A flora from the Palaeogene of Hochstetten‐Dhaun (Nahe‐area, Rhineland‐Palatinate, SW‐Germany) is described. Leaf remains of the intermediate Fagaceae species Eotrigonobalanus furcinervis (Rossmaessler) Walther & Kvaček represent the dominant element. Moreover, Equisetum sp., Tetraclinis salicornioides (Unger) Kvaček, Daphnogene cinnamomifolia (Brongniart) Unger forma lanceolata sensu Kvaček & Walther, Daphnogene cinnamomifolia (Brongniart) Unger forma cinnamomifolia sensu Kvaček & Walther, Daphnogene sp., cf. Quercus sp. vel Castaneophyllum sp., Eotrigonobalanus furcinervis (Rossmaessler) Walther & Kvaček, cf. subsp. haselbachensis Kvaček & Walther, cf. Trigonobalanopsis rhamnoides (Rossmaessler) Kvaček & Walther, and Populus cf. germanica (Menzel) Walther occur in this flora. In addition, three leaf‐morphotypes are characterized and several undeterminable leaf remains are listed. We interpret the source vegetation as a mixed mesophytic forest. Based on the composition and overall morphological and physiognomical character, we conclude that the flora is of lowermost Oligocene age.
Hieracia balcanica II. Taxonomic and nomenclatural notes on Hieracium calophyllum and its relatives (Asteraceae)
Authors: Szeląg Z.
Published: December 2002

On the basis of morphological features the taxonomic position of three taxa hitherto referred to the collective species Hieracium calophyllum R.Uechtr. is discussed. A new combination is introduced, considering H. hercegovinicum (Freyn & Vandas) Szeląg stat. nov. as a separate species. H. calophylloides Rohlena & Zahn is removed from the H. calophyllum group. Lectotypes for all names concerned are selected and illustrated.
Taxonomic significance of pollen morphology in some taxa of Resedaceae
Authors: El Naggar S.M.
Published: December 2002

Pollen morphology of 13 species and two subspecies belonging to five genera: Caylusea St.‐Hil., Ochradenus Delile, Randonia Coss., Oligomeris Cambess., and Reseda L. of Resedaceae in Egypt were investigated by light and scanning microscopy. The pollen grains were examined and separated into three pollen types and six subtypes representing the different taxonomic categories on the basis of pollen morphological characters, principally pollen shape, size and exine sculpture. The palynological results are discussed with respect to current systematic treatments of Resedaceae. According to the present palynological results, Resedaceae is a eurypalynous and not a stenopalynous family. In addition, this work came to the conclusions that further studies on the pollen of Resedaceae will be useful in establishing a phylogenetic relationship.
The delimitation, infrageneric subdivision, ecology and distribution of BomareaMirbel (Alstroemeriaceae)
Authors: Hofreiter A. , Tillich H.‐J.
Published: December 2002

The genus Bomarea (Alstroemeriaceae) was revised for the last time by Baker (1888). Since then the number of validly published names has increased from 75 to recently 280. A revision is urgently needed. Extended field studies in Peru (A. H.) revealed the experience to start this project. In the present paper the taxonomic history of the genus is described and the delimitation of Bomarea to the closely related genus Alstroemeria is analysed. Among the most important differences between the two genera are the fruit structure and the basic chromosome numbers, in Alstroemeria x = 8 and in Bomarea x = 9. The three known subgenera of Bomarea are redefined, mainly on ovary and fruit characters, and a fourth subgenus is added. The members of subgen. Bomarea s.str. (c. 100 species) have an inferior ovary and a dehiscent capsule, in subgen. Sphaerine (c. 15) the plants are always not twining, they have an inferior ovary and indehiscent and strikingly coloured fruits. In subgen. Wichuraea (c. 15) the ovary is semi‐inferior, and the fruit is a dehiscent capsule. In Baccata Hofreiter subgen. nov. (3) the plants are twining, the ovary is inferior and develops into an indehiscent fruit with a thick fleshy pericarp. A key to determine the subgenera is given in English and Spanish. For each subgenus the typical growth forms and their variability, habitat preferences and general distribution are discussed. Field studies in Peru revealed a high variability within the populations of Bomarea. Based on these experiences the systematic value of different characters is discussed. In general, the vegetative characters were found to be most variable, while selected generative characters are appropriate to characterise systematic groups. The greatest amount of character variability was found in subgen. Wichuraea, the most constant characters are found in subgen. Sphaerine.
Phallus minusculus sp. nova from Tropical Africa
Authors: Calonge F.D. , Kreisel H.
Published: December 2002

Phallus minusculus Kreisel & Calonge from Tanzania is proposed as a new species based on the morphological features, habitat, and ecology. A comparative study with related species of sect. Flavophallus Kreisel is added.
How important are economic factors in choice of medical specialty?
Authors: Thornton James , Esposto Fred
Published: December 2002

An ongoing debate exists among health care researchers about the mechanism that allocates physicians across medical specialties, and appropriate policy measures to correct imbalances that may arise from time to time. Most researchers believe that choice of residency program by medical school graduates is key to understanding how physicians are distributed across specialties, but there is much disagreement about whether economic or non‐economic factors are most influential in determining this choice. We undertake an empirical investigation of two potentially important economic factors: income and leisure. To do so, we specify a two way error component regression model to estimate the effects of expected earnings and available leisure time, and uncertainty of earnings and leisure, on specialty choices of medical residents. Our findings indicate that economic factors are an important influence in the specialty choice process; in particular, medical residents are attracted to specialties that offer the prospect of longer and more certain annual vacations, higher earnings, shorter residency programs, and more certain work schedules. Our results suggest that employment contracts that provide generous annual vacation time and promise regular weekly work schedules may be more effective than increased earnings in correcting the current perceived shortage of primary care physicians. Copyright © 2002 John Wiley & Sons, Ltd.
A utility‐theoretic model for QALYs and willingness to pay
Authors: Klose Thomas
Published: December 2002

Despite the widespread use of quality‐adjusted life years (QALY) in economic evaluation studies, their utility‐theoretic foundation remains unclear. A model for preferences over health, money, and time is presented in this paper. Under the usual assumptions of the original QALY‐model, an additive separable presentation of the utilities in different periods exists. In contrast to the usual assumption that QALY‐weights do solely depend on aspects of health‐related quality of life, wealth‐standardized QALY‐weights might vary with the wealth level in the presented extension of the original QALY‐model resulting in an inconsistent measurement of QALYs. Further assumptions are presented to make the measurement of QALYs consistent with lifetime preferences over health and money. Even under these strict assumptions, QALYs and WTP (which also can be defined in this utility‐theoretic model) are not equivalent preference‐based measures of the effects of health technologies on an individual level. The results suggest that the individual WTP per QALY can depend on the magnitude of the QALY‐gain as well as on the disease burden, when health influences the marginal utility of wealth. Further research seems to be indicated on this structural aspect of preferences over health and wealth and to quantify its impact. Copyright © 2002 John Wiley & Sons, Ltd.
Assessing and comparing costs: how robust are the bootstrap and methods based on asymptotic normality?
Authors: O'Hagan Anthony , Stevens John W.
Published: December 2002

This article addresses and challenges some common perceptions in the statistical assessment of costs and cost‐effectiveness in health economics. Cost data typically exhibit highly skew distributions. Two techniques whose validity does not depend on any specific form of underlying distribution are the bootstrap and methods based on asymptotic normality of sample means. These methods are generally thought to be appropriate for the analysis of cost data.

We argue that, even when these methods are technically valid, they may often lead to inefficient and even misleading inferences. It is important to apply methods that recognise the skewness in cost data.

We further demonstrate that it may also be important to incorporate relevant prior information in a Bayesian analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Eliciting several willingness to pay in a single contingent valuation survey: application to health care
Authors: Luchini Stéphane , Protière Christel , Moatti Jean‐Paul
Published: December 2002

The usual implementation of contingent valuation (CV), in the context of priorities setting for allocation of public funds in health care, is to develop as many surveys as there are programmes, i.e. to perform separate evaluations (SE). In the EuroWill project, three health programmes (for heart disease, breast cancer and a service of helicopter ambulance) were however simultaneously evaluated, i.e. a joint evaluation (JE) was performed. The paper examines the issue of the econometric techniques that should be used to estimate WTP values obtained in the context of JE by comparing the application of independent OLS regressions for each programme versus simultaneous estimations using seemingly unrelated regressions (SUR) on data of the French EuroWill survey. It shows that separate estimations may lead to misspecifications because they cannot take into account that JE exogenously provides a reference structure to the respondent which affects the estimates of WTP for each programme. Therefore, the potential advantage of JE versus SE as an elicitation technique in CV studies applied to health care (to better control the referents used by respondents for evaluating different programmes) only holds if simultaneous rather than independent techniques are used in the estimation of WTPs. Copyright © 2002 John Wiley & Sons, Ltd.
Estimating the monetary value of health care: lessons from environmental economics
Authors: Hanley Nick , Ryan Mandy , Wright Robert
Published: December 2002

In the recent past, considerable effort in health economics has been made on applying stated preference methods such as contingent valuation and choice experiments. Despite this increased use, there is still considerable scepticism concerning the value of these approaches. The application of contingent valuation in environmental economics has a long history and has been widely accepted. Whilst choice experiments were introduced to the environmental and health economics literature at a similar time, the wider acceptance of monetary measures of benefit in environmental economics has meant that they have also been more widely applied. The purpose of this paper is to identify some of the key issues and debates that have taken place in the environmental economics literature, summarise the state of the art with respect to these issues, and consider how health economists have addressed these issues. Important areas for future research in health economics are identified. Copyright © 2002 John Wiley & Sons, Ltd.
Histone deacetylase inhibitor trichostatin a induces cell‐cycle arrest/apoptosis and hepatocyte differentiation in human hepatoma cells
Authors: Yamashita Yo‐ichi , Shimada Mitsuo , Harimoto Norifumi , Rikimaru Tatsuya , Shirabe Ken , Tanaka Shinj , Sugimachi Keizo
Published: December 2002

Remodeling of the chromatin template by inhibition of HDAC activities represents a potential transcriptional therapy for neoplastic disease. A number of HDAC inhibitors that modulate in vitro cell growth and differentiation have been developed. We analyzed the effects of TSA, a specific and potent HDAC inhibitor, on the human hepatoma cell lines HepG2 and Huh‐7. TSA increased levels of acetylated histones H3 and H4 in both HepG2 and Huh‐7. It inhibited cell proliferation in vitro and induced G0/G1 arrest in HepG2 and apoptosis in Huh‐7. Gene expression of liver‐specific functions and liver‐enriched transcription factors was upregulated by TSA. TSA upregulated the ammonia removal rate and the albumin synthesis rate of HepG2 and Huh‐7. Our results indicate that TSA can induce cell‐cycle arrest/apoptosis and hepatocyte differentiation in human liver cancer cell lines. © 2002 Wiley‐Liss, Inc.
Detection of hematogenic and lymphogenic tumor cell dissemination in patients with medullary thyroid carcinoma by cytokeratin 20 and preprogastrin‐releasing peptide RT‐PCR
Authors: Weber Theresia , Lacroix Jeannine , Wörner Stefan , Weckauf Helgard , Winkler Steffi , Hinz Ulf , Schilling Tobias , Frank‐Raue Karin , Klar Ernst , Knebel Doeberitz Magnus von
Published: December 2002

Despite an extensive surgical approach only 50% of the patients with medullary thyroid carcinoma (MTC) are biochemically cured. The failure to cure a larger number of patients is a result of the early dissemination of MTC. The present study evaluates two RT‐PCR based assays for the detection of disseminated tumor cells in blood, bone marrow and lymph node samples of patients with MTC. Frozen tissue and blood samples of 19 patients with MTC and 61 cervical lymph nodes of these patients were obtained intraoperatively during thyroidectomy and lymphadenectomy. Preoperative bone marrow samples were obtained from 8 patients with MTC. An expression of CK20 and preproGRP was found in all MTC tissue samples. Using CK20‐PCR, disseminated MTC cells were detected in 67% of the cervical lymph nodes of patients with MTC, compared to 72% involved lymph nodes, detected by preproGRP‐PCR. In 16 of 61 nodes (26%) each PCR‐system detected disseminated tumor cells in histologically tumor‐free lymph nodes. Disseminated tumor cells were detected with CK20‐PCR and preproGRP in 5 of 18 (28%) preoperative blood samples, each. The detection of a hematogenic tumor cell dissemination by preproGRP correlated significantly with the tumor stages (p = 0.019). Circulating MTC cells were found in 3 of 8 bone marrow samples with CK20‐PCR, compared to 1 of 8 samples with preproGRP‐PCR. Both PCR assays are highly sensitive to detect disseminated MTC cells in blood, bone marrow and lymph node samples. Our results of disseminated MTC cells in 26% of histologically tumor‐free cervical lymph nodes and in 28% of the blood samples of patients with MTC might therefore explain the low biochemical cure rates. © 2002 Wiley‐Liss, Inc.
Circulating interleukin‐6 predicts survival in patients with metastatic breast cancer
Authors: Salgado Roberto , Junius Sara , Benoy Ina , Van Dam Peter , Vermeulen Peter , Van Marck Eric , Huget Philippe , Dirix Luc Y.
Published: December 2002

Interleukin‐6 (IL‐6) is a multifunctional cytokine produced by macrophages, T cells, B cells, endothelial cells and tumour cells. Interleukin‐6 is able to promote tumour growth by upregulating anti‐apoptotic and angiogenic proteins in tumour cells. In murine models it has been demonstrated that antibodies against IL‐6 diminish tumour growth. Several reports have highlighted the prognostic importance of IL‐6 in e.g., prostate and colon cancer. We addressed prospectively the prognostic significance of serum IL‐6 (sIL‐6), measured at diagnosis of metastasis, in 96 unselected and consecutive patients with progressive metastatic breast cancer before the initiation of systemic therapy. The median sIL‐6 value for the breast cancer population was 6.6 ± 2.1 pg/ml. Patients with 2 or more metastatic sites had higher sIL‐6 values compared to those with only 1 metastatic site (respectively 8.15 ± 1.7 pg/ml and 3.06 ± 6.6 pg/ml; p < 0.001). Patients with liver metastasis (8.3 ± 2.4 pg/ml), with pleural effusions (10.65 ± 9.9 pg/ml) and with dominant visceral disease (8.15 ± 3.3 pg/ml) had significantly higher values compared to those without liver metastases (4.5 ± 3.4 pg/ml; p = 0.001), without pleural effusions (5.45 ± 1.5 pg/ml; p = 0.0077) and with dominant bone disease (4.5 ± 1.4 pg/ml; p = 0.007) respectively. No correlation between sIL‐6 and age, menopausal status, performance status, tumour grade, body‐mass index, histology and hormone receptor status was found. Multivariate analysis showed that high levels of serum IL‐6 have independent prognostic value. We conclude that circulating IL‐6 is associated with worse survival in patients with metastatic breast cancer and is correlated with the extent of disease. © 2002 Wiley‐Liss, Inc.
Prognostic impact of matrix metalloproteinase‐9 in operable non‐small cell lung cancer
Authors: Sienel Wulf , Hellers Joe , Morresi‐Hauf Alicia , Lichtinghagen Ralf , Mutschler Wolf , Jochum Marianne , Klein Christoph , Passlick Bernward , Pantel Klaus
Published: December 2002

We assessed the clinical impact of MMP‐9 expression on long‐term survival in patients with operable non‐small cell lung cancer (NSCLC). Primary tumors of 143 consecutive patients with NSCLC resected completely and without overt distant metastases (pT1‐4, pN0‐2, M0, R0) were examined for MMP‐9 expression using immunohistochemistry with a polyclonal, affinity‐purified rabbit antibody that recognizes both latent and active MMP‐9. Immunohistochemical staining of tumor cells was evaluated in comparison to normal bronchiolar epithelium that served as an internal positive control. MMP‐9 expression was categorized into negative, ≤5% tumor cells stained; heterogeneous, >5% and <95% tumor cells stained; and homogeneous, ≥95% tumor cells stained at least as intensively as bronchiolar epithelium. The median follow‐up period was 72 months (range = 12–144 months). Homogeneous expression of MMP‐9 was observed in 26 of 143 patients (18.2%) and did not correlate with clinicopathological parameters. Relapse defined as diagnosis of distant metastasis or local recurrence was observed in 78 of the 130 (60%) patients eligible for clinical follow up analysis. Relapse led to cancer‐related death in all of the 78 patients within the observation period. Kaplan‐Meier analysis showed a significant association between homogeneous MMP‐9 expression and shortened cancer‐related survival (log‐rank p = 0.016). Multivariate regression analysis including pT‐status, pN‐status, tumor histology and tumor grading showed an independence of this prognostic impact of homogeneous MMP‐9 expression (p = 0.045). Thus, immunohistochemical evaluation of MMP‐9 expression may provide a basis for the preselection of patients to be included in trials investigating specific protease inhibitor therapy after surgical resection of NSCLC. © 2002 Wiley‐Liss, Inc.
Experimental photodynamic therapy with MESO‐tetrakisphenylporphyrin (TPP) in liposomes leads to disintegration of human amelanotic melanoma implanted to nude mice
Authors: Ježek Petr , Nekvasil Milos , Škobisová Eva , Urbánková Eva , Jirsa Milan , Zadinová Marie , Poučková Pavla , Klepáček Ivo
Published: December 2002

Liposomal meso‐tetrakis‐phenylporphyrin (TPP) was tested for photodynamic therapy (PDT) of human amelanotic melanomas implanted in nude mice. After intratumoural TPP application (15 mg.kg−1) followed by PDT lamp irradiation (600–700 nm, 635 nm peak), tumours retained their original volume up to the 23rd day post‐PDT, whereas volumes increased 6 times in controls. PDT with intravenously (i.v.) administered liposomal (3.2 mg.kg−1) TPP mostly disintegrated tumours to zero volumes. Melanoma remissions were accompanied by tumour surface necroses and were documented by the appearance of nontumourous cells with nonpycnotic nuclei. Spatial arrangement of capillaries in remissing tumour was the same as in healthy surrounding tissue. Lower TPP doses (1, 0.3 and 0.1 mg.kg−1) were more or equally efficient than hydrophilic TPPS4 (3.2 mg.kg−1, i.e., sulfonated TPP), i.v. administered also in liposomes. Liposomal TPPS4 only delayed the onset of subsequent tumour growth. Commercial Photosan 3 disintegrated tumours only in doses of approx. 7.5 mg.kg−1; in lower doses it was less efficient than TPPS4. The second PDT cycle (3.2 mg.kg−1 TPP or 7.5 mg.kg−1 Photosan 3), performed in a few unsuccessfully cured mice, predominantly led again to tumour remissions. Since the measured TPP and TPPS4 content in melanomas was similar, these results demonstrate the advantage of PDT with a hydrophobic photosensitizer such as TPP. Photophysical properties of TPP and TPPS4 are equal, but TPP has probably more favorable intracellular distribution, as documented by our studies, which leads to more efficient PDT. Consequently, liposomal TPP is suggested as a potentially suitable efficient preparation for PDT. © 2002 Wiley‐Liss, Inc.
Serum selenium and risk of prostate cancer in U.S. blacks and whites
Authors: Vogt Tara M. , Ziegler Regina G. , Graubard Barry I. , Swanson Christine A. , Greenberg Raymond S. , Schoenberg Janet B. , Swanson G. Marie , Hayes Richard B. , Mayne Susan T.
Published: December 2002

Prostate cancer is the fourth most common cancer in men worldwide and the most common cancer in men in the United States, with reported incidence rates for U.S. blacks being the highest in the world. The etiology of prostate cancer and an explanation for the racial disparity in incidence in the United States remain elusive. Epidemiologic studies suggest that selenium, an essential trace element, may protect against the disease. To further explore this hypothesis, we measured serum selenium in 212 cases and 233 controls participating in a multicenter, population‐based case‐control study that included comparable numbers of U.S. black and white men aged 40–79 years. Serum selenium was inversely associated with risk of prostate cancer (comparing highest to lowest quartiles, OR = 0.71, 95% CI 0.39–1.28; p for trend = 0.11), with similar patterns seen in both blacks and whites. Cubic regression spline analysis of continuous serum selenium indicated a reduced risk of prostate cancer above concentrations of 0.135 μg/ml (median among controls) compared to a reference value set at the median of the lowest selenium quartile. Because both the selenoenzyme GPX and vitamin E can function as antioxidants, we also explored their joint effect. Consistent with other studies, the inverse association with selenium was strongest among men with low serum α‐tocopherol concentrations. In conclusion, our results suggest a moderately reduced risk of prostate cancer at higher serum selenium concentrations, a finding that can now be extended to include U.S. blacks. Since selenium exposure varies widely throughout the world, further research on optimal concentrations for cancer prevention is justified. © 2002 Wiley‐Liss, Inc.
Breast cancer revisited using DNA array‐based gene expression profiling
Authors: Bertucci François , Viens Patrice , Hingamp Pascal , Nasser Valery , Houlgatte Rémi , Birnbaum Daniel
Published: December 2002

Breast cancer is a complex genetic disease characterized by the accumulation of multiple molecular alterations. The resulting clinical heterogeneity makes current diagnostic and therapeutic strategies less than perfectly adapted to each patient. Pathological and clinical factors are insufficient to capture the complex cascade of events that drive the clinical behavior of tumors. High‐throughput molecular technologies provide novel tools to tackle this complexity. In particular, DNA arrays allow the simultaneous and quantitative analysis of the mRNA expression levels of thousands of genes in a single assay. Potential applications are multiple in the cancer field and the first research results are promising; comprehensive gene expression profiles of breast tumors are providing insights into mammary oncogenesis and are revealing new tumor subgroups previously indistinguishable. Significant advances will be the identification of new diagnostic, prognostic and predictive biomarkers as well as the discovery of new potential therapeutic targets. This review presents recent applications of DNA arrays in breast cancer research and discusses some issues to address in the near future to allow the technology to reach its full potential. © 2002 Wiley‐Liss, Inc.
CDKN2A region polymorphism and genetic susceptibility to melanoma in the melim swine model of familial melanoma
Authors: Le Chalony Catherine , Renard Christine , Vincent‐Naulleau Silvia , Crechet Françoise , Leplat Jean‐Jacques , Tricaud Yves , Horak Vratislav , Gruand Joseph , Le Roy Pascale , Frelat Gérard , Geffrotin Claudine
Published: December 2002

Some herds of miniature swine are genetically predisposed to cutaneous melanoma. To test if swine melanoma susceptibility could be linked to the CDKN2A gene, which is involved in a proportion of 9p21‐linked human familial melanoma, we performed a genetic analysis of miniature pigs of the MeLiM strain. F1 and backcross animals were generated by crossing 1 MeLiM boar with healthy Duroc sows. We isolated the swine CDKN2A gene and characterized a linked informative microsatellite marker, the S0644 marker. Using this marker and 2 flanking markers, we analyzed the segregation of the CDKN2A gene in a 3‐generation pedigree. Allelic association, linkage analysis and haplotype analysis of these data led to exclusion of the CDKN2A gene as a candidate for melanoma susceptibility. Nonetheless, this analysis suggests an association with the swine 1q25 chromosomal region, which is homologous to the human 9p21 region. © 2002 Wiley‐Liss, Inc.
Prostaglandin J2 metabolites inhibit aromatase activity by redox‐sensitive mechanisms: Potential implications for breast cancer therapy
Authors: Winnett Georgia , van Hagen Daphne , Schrey Michael
Published: December 2002

The mechanisms by which prostaglandin (PG)J2 metabolites inhibit tumorigenicity are poorly understood but may involve thiol reactivity or peroxisome proliferator‐activated receptor (PPAR)‐dependent pathways. Because aromatase is an important therapeutic target in breast cancer treatment, we have investigated the effect of PGJ2 metabolites on aromatase activity and evaluated a potential role for redox status during PGJ2 metabolite action. 15‐deoxy‐Δ12,14PGJ2 (15d‐PGJ2) and 9‐deoxy‐Δ9,1213,14‐dihydroPGD2 (Δ12PGJ2) caused dose‐dependent inhibition of both pre‐induced aromatase activity in human breast fibroblasts and MDA MB 231 breast cancer cells and of constitutive aromatase activity in JEG‐3 choriocarcinoma cells. Structure‐activity studies showed that this inhibition was mimicked by 4‐cyclopentene‐1,3‐dione but not by the PPARγ agonist troglitazone nor the eicosanoids PGE2 or arachidonic acid. The thiol oxidants diamide and H2O2 simulated the inhibitory action of 15d‐PGJ2 on aromatase activity, whereas the glutathione (GSH) repletor and antioxidant N‐acetyl‐cysteine (NAC) reversed these actions of 15d‐PGJ2 and H2O2 on aromatase. 15d‐PGJ2 also caused a direct dose‐dependent inhibition of aromatase activity in JEG‐3 cell sonicates, which was also reversed in the presence of GSH. Kinetic analysis of this 15d‐PGJ2‐induced inhibition of cell‐free aromatase indicated the involvement of a non‐competitive mechanism possibly resulting from direct thiol‐targeted alkylation of the enzyme. These redox‐sensitive, PPARγ‐independent actions of 15d‐PGJ2 on aromatase activity demonstrate a novel therapeutic potential for such cyclopentenone PGs in breast cancer treatment. © 2002 Wiley‐Liss, Inc.
Regeneration of serous membrane on gelatin‐processed polyglycolic acid (PGA)‐human collagen membrane and its efficacy on the prevention of adhesion
Authors: Lee Yong Ho , Nakamura Tatsuo , Shimizu Yasuhiko , Yamamoto Yasumich , Kiyotani Tetsuya , Tsuda Touru , Teramachi Masayoshi , Takimoto Yukinobu
Published: December 2002

We prepared a complex membrane consisting of human amnion‐derived collagen membrane and polyglycolic acid (PGA), and then gelatin was crosslinked using heat on one side of the complex membrane to prepare a membrane that can prevent adhesion (gelatin‐processed PGA–human collagen membrane). Applying this membrane to a rabbit cecum‐abdominal‐wall‐adhesion model, the prevention of adhesion and tissue regeneration were investigated. The animals were sacrificed 2 and 12 weeks after surgery and then examined. The adhesion scores in the short‐term observation group (2 weeks after surgery) and long‐term observation group (12 weeks after surgery) were 1.0 ± 2.4 and 0.8 ± 2.0, respectively, showing a significant prevention of adhesion compared to the control value of 6.3 ± 2.5 (p < 0.01). Histologically, gelatin was not absorbed, and outgrowth of connective tissue accompanied by capillary blood vessels was observed between the sample and the cecum in the short‐term observation group. In the long‐term observation group, the sample was completely absorbed, and serous membrane was regenerated on the surface of connective tissue. Based on these findings, it is possible to use gelatin‐processed PGA–human collagen membrane as a filling material with both an adhesion‐preventing effect and tissue‐regenerating function. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 88–92, 2003
Preparation of epoxy–SiO2 hybrid sol–gel material for bone cement
Authors: Yang Jen Ming , Shih Chun Hsiung , Chang Chen‐Nen , Lin Feng Huei , Jiang Jian Ming , Hsu Ying Gev , Su Wen Yu , See Lai Chu
Published: December 2002

An organic–inorganic hybrid material, epoxy–SiO2, was prepared by incorporating epoxy structure units covalently into a SiO2 glass network via the sol–gel approach. The precursor was obtained by the reaction of diglycidyl ether of bisphenol A (DGEBA) with 3‐aminopropyl trimethoxysilane (APTS). The precursor was then hydrolyzed and co‐condensated with tetraethyl orthosilicate (TEOS) in tetrahydrofuran (THF) at room temperature to yield epoxy–SiO2 hybrid sol–gel material having a 50 wt % SiO2 content. Thermal properties of the hybrid material were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hybrid sol–gel material epoxy–SiO2 was the solid, powder component of bone cement. The liquid component contains bis‐phenol‐A glycidyl methacrylate (Bis‐GMA), triethyleneglycol dimethacrylate (TEGDMA), and methyl methacrylate (MMA) with 25, 55, and 20 vol %, respectively. We discuss the comparison between the new epoxy–SiO2 bone cement and the commercial Simplex® P bone cement. Mechanical properties such as Young's modulus, compressive strength, hardness, and impact strength of the new epoxy–SiO2 bone cement exceeded those of SimplexR P bone cement. The tensile and bending strengths of the new epoxy–SiO2 bone cement were approximately the same as those of Simplex® P bone cement. In order to evaluate the biocompatibility of the new bone cement, an MTT test and optical microscopy were conducted in cell culture. Results indicated that the new epoxy–SiO2 bone cement exhibits very low cytotoxicity compared with Simplex® P bone cement. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 138–146, 2003
Quantitative analysis of binary adsorbed protein films by time of flight secondary ion mass spectrometry
Authors: Wagner M. S. , Shen M. , Horbett T. A. , Castner David G.
Published: December 2002

Time of flight secondary ion mass spectrometry (ToF‐SIMS) is an ideal technique for the analysis of adsorbed protein films because of its surface sensitivity and chemical specificity. In this study, we examined ToF‐SIMS with the multivariate calibration method partial least squares regression (PLSR) for the determination of the relative abundance of the components in binary protein films adsorbed onto mica, PTFE, and heptyl amine plasma polymer substrates. These results have been compared with independently measured 125I‐radiolabeled protein adsorption experiments. By applying PLSR to the ToF‐SIMS data, the relative abundance of the components in the binary adsorbed protein films was quantified, and the agreement between the ToF‐SIMS and 125I‐radiolabeling data was measured by the root mean square prediction error (RMSPE). Differences in protein quantification by PLSR and 125I‐radiolabeling ranged from 5 to 25 mass % RMSPE and were highly dependent on the structure of the adsorbed protein film, the substrate surface chemistry and morphology, and the number of latent variables retained in the PLSR model. The limit of detection for the minor component in the adsorbed protein film was found to be approximately 10 mass %. This study demonstrates that the combination of ToF‐SIMS and multivariate calibration provide complementary information to 125I‐radiolabeling about the composition and structure of binary adsorbed protein films. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 1–11, 2003
Development of new hydroactive dressings based on chitosan membranes: Characterization and in vivo behavior
Authors: de Queiroz Alvaro Antonio Alençar , Ferraz Humberto Gomes , Abraham Gustavo Abel , del Mar Fernández María , Bravo Antonio López , Román Julio San
Published: December 2002

Different poly(vinyl alcohol) (PVA)/chitosan lactate (ChL)‐blended hydrogels containing nitrofurazone as a local anti‐infective drug were prepared by the phase‐inversion technique. The swelling degree, surface free energy, mechanical properties, and nitrofurazone release of these membranes were determined. Blood compatibility of these systems was evaluated by the open‐static platelet adhesion test with whole human blood. The results showed that water absorption into the PVA/ChL membranes slowed down, governed by the rate at which the dressing interacted with the physiological fluid. Swelling degree values up to 200% were observed. The rate of release of nitrofurazone seemed to depend on the ChL percentage on the blend as well as the pH of the solution. The surface free energy values were in the range of 20–30 dynes/cm, which was appropriate for a favorable interaction with blood. From the Young's module curve, it could be seen that elastic hydrogels were obtained with increment of ChL in the PVA/ChL blends. Values of platelet adhesion and whole blood clotting times for the PVA/ChL blends as well as the increase of ChL, which appears to reduce the fibrinogen adsorption on the PVA/ChL membranes, demonstrated that the blood compatibility of PVP/ChL blends is superior to that separated polymers. The results of in vivo experiments in rats were in very good agreement with these observations, suggesting that PVA/ChL may serve as a new type of potential wound‐dressing material. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 147–154, 2003
Histocompatibility of photocrosslinked polyanhydrides: A novel in situ forming orthopaedic biomaterial
Authors: Poshusta Amy K. , Burdick Jason A. , Mortisen Derek J. , Padera Robert F. , Ruehlman Dana , Yaszemski Michael J. , Anseth Kristi S.
Published: December 2002

Cell–polymer interactions in subcutaneous and bony tissue were examined for a novel class of in situ forming and surface eroding polyanhydride networks. Specifically, photopolymerized disks of several polyanhydride compositions were implanted subcutaneously in rats, and the tissue was analyzed for an inflammatory response. The compositions elicited varied histological responses, ranging from highly active cell layers to moderate fibrous capsules, depending on the degrading polymer composition. Furthermore, one composition was photopolymerized in a model orthopaedic defect in the proximal tibia. The feasibility of photopolymerizing the methacrylated monomers in situ and the adherence of the photocrosslinked polyanhydride to the medullary canal were examined. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 62–69, 2003
Fabrication of micropored elastomeric film‐covered stents and acute‐phase performances
Authors: Nakayama Yasuhide , Nishi Shogo , Ueda‐Ishibashi Hatsue , Matsuda Takehisa
Published: December 2002

To prevent thrombus formation in the acute phase and restenosis in the subacute to chronic phase after stenting of atherosclerotic arteries, we developed a covered stent with a micropored elastomeric film, the blood‐contacting surface of which was coated with a photocured gelatin layer immobilized with heparin. Segmented polyurethane (SPU) film (30 μm in wall thickness) as a cover material was multiply micropored by excimer laser‐directed microprocessing (pore diameter, 30 μm; interpore distance, 125 μm). An aqueous mixed solution of benzophenone‐derivatized gelatin and heparin was coated on the micropored SPU film. Upon ultraviolet light irradiation, a thin layer of a gelatin gel immobilized with heparin was formed and simultaneously fixed on the SPU film. The fully covered stents were assembled by wrapping a balloon‐expandable stent with gelatin/heparin gel‐layered SPU film and subsequently suturing and then gluing. To assess the validity of this covered stent in vivo, “half‐covered” stents, in which half at the distal side was covered with the gel‐layered SPU film, was implanted in rabbit common carotid arteries (about 3 mm in diameter). After 3 months of implantation, all the half‐covered stents (n = 7) were patent. Regardless of the covered or noncovered region of the stents, the entire luminal surface of the stents was fully endothelialized and a thin neointimal tissue was formed. The potential advantages of a covered stent as designed above are discussed. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 52–61, 2003
Correlating fibronectin adsorption with endothelial cell adhesion and signaling on polymer substrates
Authors: Koenig Andrea L. , Gambillara Veronica , Grainger David W.
Published: December 2002

Fibronectin (Fn) adsorption was studied on different commercial polymer surface chemistries, including tissue culture polystyrene (TCPS), bacteriologic polystyrene (BPS), fluoropolymer Teflon AF®, and poly‐L‐lactide (PLLA). Antibody probes detected the availability of Fn's cell binding domain on adsorbed Fn in the competitive presence and absence of bovine serum albumin (BSA). Domain availability was highest for Fn adsorbed on TCPS, especially in the presence of either serum albumin or dilute serum. Attachment and growth efficiencies for human umbilical venous endothelial cells (HUVECs) cultured on surfaces preadsorbed with Fn in serum and serum‐free media correlated with antibody cell‐binding domain availability: TCPS > BPS, Teflon AF® > PLLA. Intracellular signaling from the GTPase, RhoA, was highest (RhoA:RhoGDI inhibitor ratio) in cells cultured on the Teflon AF® surfaces, indicating that despite lower attached cell numbers on Teflon AF® compared to TCPS, cell signaling remained activated after 24 h of growth. Up‐regulated cellular Fn mRNA messages, assessed using RT‐PCR techniques, supported HUVECs' producing the endogenous extracellular matrix (ECM) protein Fn in order to attach and survive on the suboptimal Teflon AF® culture surfaces. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 20–37, 2003
Controlling the spatial distribution of ECM components in degradable PEG hydrogels for tissue engineering cartilage
Authors: Bryant Stephanie J. , Anseth Kristi S.
Published: December 2002

In developing a scaffold to support new tissue growth, the degradation rate and mass loss profiles of the scaffold are important design parameters. In this study, hydrogels were prepared by copolymerizing a degradable macromer, poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid) endcapped with acrylate groups (PEG‐LA‐DA) with a nondegradable macromer, poly(ethylene glycol) dimethacrylate (PEGDM). The resulting hydrogels exhibited a range of degradation behavior and mass loss profiles. Chondrocytes were photoencapsulated in gels formulated with 50:50, 25:75, and 15:85 (mol % PEGDM: mol % PEG‐LA‐DA) and cultured for 6 weeks in vitro. The neocartilaginous tissue formed was examined biochemically and histologically. After 6 weeks, the DNA content in gels with 75 and 85% degradable crosslinks was nearly twice that of the DNA content in the 50% gels. The total collagen content was significantly higher in the 85% gel [2.4 ± 0.8% wet weight (ww)] compared to the 50% gel (0.22 ± 0.29% ww). In examining the neocartilaginous tissue with immunohistochemistry, type II collagen was localized in the pericellular region in the 50% gel; however, when increased degradation was incorporated into the gel, type II collagen was found throughout the neotissue. In summary, the important role of hydrogel degradation in controlling and influencing the deposition and distribution of extracellular matrix molecules was demonstrated and quantified. © 2002 Wiley Periodicals, Inc., J Biomed Mater Res 64A: 70–79, 2003
Peptide‐modified p(AAm‐co‐EG/AAc) IPNs grafted to bulk titanium modulate osteoblast behavior in vitro
Authors: Barber Thomas A. , Golledge Stephen L. , Castner David G. , Healy Kevin E.
Published: December 2002

Interpenetrating polymer networks (IPNs) of poly(acrylamide‐co‐ethylene glycol/acrylic acid) (p(AAm‐co‐EG/AAc) applied to model surfaces prevent protein adsorption and cell adhesion. Subsequently, IPN surfaces functionalized with the RGD cell‐binding domain from rat bone sialoprotein (BSP) modulated bone cell adhesion, proliferation, and matrix mineralization. The objective of this study was to utilize the same biomimetic modification strategy to produce functionally similar p(AAm‐co‐EG/AAc) IPNs on clinically relevant titanium surfaces. Contact angle goniometry and X‐ray photoelectron spectroscopy (XPS) data were consistent with the presence of the intended surface modifications. Cellular response was gauged by challenging the surfaces with primary rat calvarial osteoblast (RCO) surfaces in serum‐containing media. IPN modified titanium and negative control (RGE‐IPN) surfaces inhibit cell adhesion and proliferation, while RGD‐modified IPNs on titanium supported osteoblast attachment and spreading. Furthermore, the latter surfaces supported significant mineralization despite exhibiting lower levels of proliferation than positive control surfaces. These results suggest that with the appropriate optimization, this approach may be practical for surface engineering of osseous implants. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 38–47, 2003
Oxygenation of hypoxic region in solid tumor by administration of human serum albumin incorporating synthetic hemes
Authors: Kobayashi Koichi , Komatsu Teruyuki , Iwamaru Arifumi , Matsukawa Yasuko , Horinouchi Hirohisa , Watanabe Masazumi , Tsuchida Eishun
Published: December 2002

Recombinant human serum albumin incorporating synthetic heme (rHSA‐FeP) was tested for its ability to increase O2 tension in the hypoxia of the solid tumor rat model. By the direct administration of the rHSA‐FeP solution (10 mL/kg) via the aorta descendens to the ascites hepatoma LY80 tumor on the right femur, the O2 tension of the hypoxic region immediately increased to 3.45 ± 1.43 Torr, which corresponds to a 2.4‐fold increase compared to that of the baseline value. These high O2 levels continued for 300 s after the infusion. The rHSA‐FeP solution can be utilized not only as a red blood cell substitute but also as an O2‐carrying medicine for the effective reoxygenation of the hypoxia solid tumor. © 2002 Wiley Periodicals Inc. J Biomed Mater Res 64A: 48–51, 2003
Influence of local complications on capsule formation around model implants in a rat model
Authors: Eltze E. , Bettendorf O. , Rody A. , Jackisch C. , Herchenröder F. , Böcker W. , Pfleiderer B.
Published: December 2002

We studied the capsule formation around various filled breast implants and other related changes in distant organs (e.g., liver, spleen, lymph nodes) in a rat model 3 and 6 months after implantation. Model implants, one per rat, (filled with saline, n = 19; silicone, n = 14; cohesive silicone, n = 17; and hydrogel, n = 19) were implanted subcutaneous in the lower back of rats. The animals were sacrificed regularly after 3 and 6 months of implantation or when wound defects occurred. The capsules and organs were examined histologically, and immunohistology of the capsules was performed. A monoclonal antibody specific for AIF‐1 (allograft inflammatory factor 1) was used to detect activated macrophages. Wound defects occurred most frequently after implantation of saline and hydrogel implants. Increased capsule thickness was associated with increased grade of inflammation, fibrosis, and the type of implant filling. There was a significant positive correlation between capsule thickness, presence of chronic inflammation, and AIF‐1‐positive macrophages (p < 0.0001), indicating that inflammation plays an important role in capsule formation. Remarkably, saline and silicone implants (in absence of local complications) cause only a blande slight fibrosis in capsules after 6 months of implantation, whereas capsules around cohesive silicone implants exhibited a more severe fibrosis with an increased capsule thickness. Most importantly, hydrogel seems to be most potent to induce an inflammatory infiltrate with AIF‐1 expressing macrophages at the implantation site, independent of implantation time, and capsules also produced a significant increase in thickness after 6 months. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 12–19, 2003