bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclic AMP inhibits TGFβ1‐induced cell‐scattering and invasiveness in murine‐transformed keratinocytes
Authors: Santibáñez Juan F. , Olivares Daniela , Guerrero Javier , Martínez Jorge
Published: October 2003

Mouse‐transformed keratinocytes cultured in the presence of transforming growth factor β1 (TGF‐β1) acquire an array of morphologic and functional properties that give rise to a migratory phenotype that expresses mesenchymal molecular markers. This cellular conversion involves activation of the Ras‐ERK pathway, enhancement of urokinase (uPA) and matrix metalloproteinase‐9 (MMP‐9) expression and induction of invasiveness. In our present work, we demonstrate that cAMP and forskolin are able to prevent the expression of these mesenchymal properties, probably due to blockade of the Ras‐ERK pathway. Our results also show that cAMP and forskolin are able to abolish the TGF‐β1‐induced reorganization of the actin cytoskeleton that is characteristic of the mesenchymal phenotype and also inhibits the disruption of the E‐cadherin cell to cell interactions. The latter responses seem to depend on the activity of protein kinase A, as demonstrated by the activation of the Ras‐ERK pathway by specific protein kinase A inhibitors. © 2003 Wiley‐Liss, Inc.
Freshly isolated bone marrow cells induce death of various carcinoma cell lines
Authors: Larmonier Nicolas , Ghiringhelli François , Larmonier Claire B. , Moutet Monique , Fromentin Annie , Baulot Emmanuel , Solary Eric , Bonnotte Bernard , Martin François
Published: October 2003

In some carcinomas such as digestive tract carcinomas, bone marrow infiltration by tumor cells is a frequent event but usually remains a micrometastatic disease and rarely induces overt bone lesions. The mechanisms responsible for the control of these metastases in the bone marrow remain poorly known. We show that freshly isolated bone marrow cells from human, murine and rat origin rapidly kill a wide range of syngeneic or xenogeneic carcinoma cell lines in culture. Further analysis of this cytotoxic process in the rat indicated that neither resident bone marrow macrophages nor NK cells were responsible for this cytotoxic effect that was restricted to a subpopulation of bone marrow cells expressing CD90 (Thy‐1), a marker of hemopoietic precursors. The tumoricidal activity of these cells did not require long‐term culture nor addition of exogenous cytokines or growth factors. A subset of CD90+ cells that rapidly differentiates into CD163(ED2)‐expressing macrophages was observed to be responsible for tumor cell killing. These macrophages induced a non‐apoptotic death of tumor cells, a process that required both a direct interaction with the tumor cell and nitric oxide (NO) production through the activation of inducible nitric oxide‐synthase (iNOS). This ability of pluripotent hemopoietic stem cells to rapidly differentiate into macrophages capable of killing invasive tumor cells may account for the limited expansion of micrometastases of some carcinomas in the bone marrow. © 2003 Wiley‐Liss, Inc.
Clinical value of p53, c‐erbB‐2, CEA and CA125 regarding relapse, metastasis and death in resectable non‐small cell lung cancer
Authors: Pollán Marina , Varela Gonzalo , Torres Antonio , de la Torre Mercedes , Ludeña M Dolores , Ortega M Dolores , Pac Joaquín , Freixenet Jorge , Gómez Guillermo , Sebastián Fernando , Díez Manuel , Arrabal Ricardo , Canalís Emili , García‐Tirado Javier , Arnedillo Aurelio , Rivas Juan José , Minguella Joan , Gómez Ana , García Mauricio , Aragonés Nuria , Pérez‐Gómez Beatriz , López‐Abente Gonzalo , González‐Sarmiento Rogelio , Rojas Jose María
Published: October 2003

The prognostic value of p53 and c‐erbB‐2 immunostaining and preoperative serum levels of CEA and CA125 was investigated in a prospective multicentric study including 465 consecutive non‐small cell lung cancer (NSCLC) patients with resectable tumors. Four end‐points were used: lung cancer death, first relapse (either locoregional or metastasis), loco‐regional recurrence and metastasis development. Standard statistical survival methods (Kaplan‐Meier and Cox regression) were used. The specificity of the prognostic effect across different types of tumors was also explored, as had been planned in advance. Our results showed, once again, that pathological T and N classifications continue to be the strongest predictors regarding either relapse or mortality. Three of the studied markers seemed to add further useful information, however, but in a more specific context. For example, increased CEA concentration defined a higher risk population among adenocarcinomas but not among people with squamous tumors; and p53 overexpression implied a worse prognosis mainly in patients with well differentiated tumors. The analysis of type of relapse proved to be very informative. Thus, CA125 level was associated with a worse prognosis mainly related with metastasis development. Another interesting result was the influence of smoking, which showed a clear dose‐response relationship with the probability of metastasis. For future studies, we recommend the inclusion of different endpoints, namely considering the relationship of markers with the type of relapse involved in lung‐cancer recurrence. They can add useful information regarding the complex nature of prognosis. © 2003 Wiley‐Liss, Inc.
Local carboplatin delivery and tissue distribution in livers after radiofrequency ablation
Authors: Szymanski‐Exner A. , Gallacher A. , Stowe N. T. , Weinberg B. , Haaga J. R. , Gao J.
Published: October 2003

This study investigated the local drug pharmacokinetics of intralesional drug delivery after radiofrequency ablation of the liver. We hypothesized that the tissue architecture damaged by the ablation process facilitates the drug penetration in the liver and potentially enlarges the therapeutic margin in the local treatment of cancer. The delivery rate and tissue distribution of carboplatin, an anticancer agent, released from poly(D,L‐lactide‐co‐glycolide) implants into rat livers after radiofrequency ablation were quantified by atomic absorption spectroscopy. Results showed that carboplatin clearance through blood perfusion was significantly slower in the ablated livers, leading to a more extensive tissue retention and distribution of the drug. The concentration of Pt at the implant–tissue interface ranged from 234 to 1440 μg Pt/(g liver) in the ablated livers over 144 h versus 56 to 177 μg Pt/(g liver) in the normal tissue. The maximum penetration distance at which Pt level reached above 6 μg/g (calculated based on a reported IC90 value for carboplatin) was 8–10 mm and 4–6 mm in ablated and normal liver, respectively. Histological analysis of the necrotic lesions showed widespread destruction of tissue structure and vasculature, supporting the initial hypothesis. This study demonstrated that intralesional drug delivery could provide a sustained, elevated concentration of anticancer drug at the ablation boundary that has the potential to eliminate residual cancer cells surviving radiofrequency ablation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 510–516, 2003
Effect of increasing silver content in phosphate‐based glasses on biofilms of Streptococcus sanguis
Authors: Mulligan A. M. , Wilson M. , Knowles J. C.
Published: October 2003

Silver is a powerful antibacterial ion that may be useful for dealing with localized infections, such as periodontitis. However, the use of silver in this role could be significantly improved by the development of an effective means of delivery. Phosphate‐based glasses may provide a means of delivering the ions in a controlled manner. In our study, we have examined the effect of increasing silver content in phosphate‐based glasses on biofilms of Streptococcus sanguis. Glasses of nominally the same dissolution rate were doped with silver at 1, 5,10, and 15 mol % and the number of colony‐forming units (CFUs) determined after 6 and 24 h in a constant depth film fermenter (CDFF). The 1 mol % silver showed little change between 6 and 24 h. However, only 0.5 log CFUs were present on the glass containing 5 mol % at 6 h, and this reduced to virtually zero at 24 h. Few viable bacteria were found on the 10 mol % glass at both 6 and 24 h. The 15 mol % glass was investigated in this experiment, but no viable counts were detected. In a second set of experiments, glasses with 10 and 15 mol % silver were tested in the CDFF for up to 192 h. For the 10 mol % silver glass, there was ∼0.8 log CFUs on this glass, which dropped to almost zero at 50 h. This was approximately 1.5–2.0 log reduction in CFUs compared to controls, and this difference was maintained for the first 50 h. After 50 h, there was a slow increase in the CFUs on all samples. However, CFUs on the 10 mol % silver glass were still suppressed up to 192 h compared to the controls. However, both controls also exhibited a decrease in viable counts at 50 h; this may have been due to carryover of silver into the control sample holders. However, this was minimized by the specimen layout in the CDFF and by having gaps between specimen sets. For the 15 mol % silver glass, counts for both this glass and the controls decreased to virtually zero between 24 and 48 h, but the numbers slowly increased up to 170 h, but the number of CFUs was suppressed compared to the 10 mol % glass at the same time point. The decrease seen is clearly the effect of the silver ions; however, the slow increase in CFUs may be accounted for by the biofilms forming thick layers on top of the glass discs inhibiting the release of ions from the glass by forming a “sacrificial layer” through which further ions have to diffuse. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 401–412, 2003
Fatigue and fracture toughness of acrylic bone cements modified with long‐chain amine activators
Authors: Deb S. , Lewis G. , Janna S. W. , Vazquez B. , San Roman J.
Published: October 2003

The composition of acrylic bone cement has been identified as one of the important parameters affecting its mechanical properties and may, in turn, ultimately influence the longevity of a cemented arthroplasty. Our aim in this study was to determine the influence of change of one compositional variable, the activator, on the fatigue performance and fracture toughness of specimens of the fully cured cement. To that end, three sets of cements were prepared, containing either the conventional activator, 4‐N,N dimethyl p‐toluidine (DMPT), or novel ones that are tertiary amines based on long‐chain fatty acids, that is, 4‐N,N dimethylaminobenzyl oleate (DMAO) and 4‐N,N dimethylaminobenzyl laurate (DMAL). In the fatigue tests, the specimens were subjected to tension–tension loading, and the results (number of cycles to failure, Nf) were analyzed using the linearized form of the three‐parameter Weibull equation. The fracture toughness (KIc) tests were conducted with rectangular compact tension specimens. All fracture surfaces were subsequently examined with scanning electron microscopy. We found that the Weibull mean fatigue lives for specimens fabricated using the DMPT, DMAL, and DMAO containing cements were 272,823, 453,551, and 583,396 cycles, respectively. The corresponding values for KIc were 1.94 ± 0.05, 2.06 ± 0.09, and 2.00 ± 0.07 MPa√m, respectively. Statistical analyses showed that for both the DMAL‐ and DMAO‐containing cements, the mean values of Nf were significantly higher compared to the corresponding value for the DMPT‐containing cement (Mann–Whitney test; α < 0.10). This result is attributed to the higher molecular weights of the former cements compared to the latter. The same trend was found for the mean KIc values (Mann–Whitney test; α < 0.05), with the trend being explained in terms of the differences seen in the crack morphologies. These results thus demonstrate that these novel amines are viable alternatives to DMPT for incorporation into acrylic bone cement formulations in the future. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 571–577, 2003
Electrical polarization of bioactive glass and assessment of their in vitro apatite deposition
Authors: Obata Akiko , Nakamura Satoshi , Moriyoshi Yusuke , Yamashita Kimihiro
Published: October 2003

We evaluated the electrical polarizability of a bioactive glass of the 45S5 type (BG) by thermally stimulated depolarization current (TSDC) measurement based on the effects of the surface charges generated by an electrical polarization treatment on the growth of calcium phosphate crystals in simulated body fluid (SBF). From the results of the TSDC measurements, the polarized BG showed broad peaks in the depolarization current density spectra. The stored electrical charges calculated from the TSDC measurements of the BG polarized with an electrical dc field of 10 V · cm−1 at 500°C for 1 h was 8.5 mC · cm−2 and depended on the electrical dc field intensity. The depolarization of the BG was assumed to be due to a migration of sodium ions and influenced by transitions of the BG structure. The immersion tests with the SBF showed that the effects of the electrical polarization produced morphologic changes in the calcium phosphate deposit grown on the BG after the short period of 2 h. We expected the effects to be caused by a change in the ion concentrations in the surrounding SBF due to the surface charges of the polarized BG. The change in the ion concentrations induced the difference in the calcium phosphate deposition. Consequently, we confirmed that BG had an electrical polarizability, a possibility of storing large charges, and differences in the growth of the calcium phosphate deposit due to the effects of the surface charges. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 413–420, 2003
Protein adsorption and smooth muscle cell adhesion on biodegradable agmatine‐modified poly(propylene fumarate‐co‐ethylene glycol) hydrogels
Authors: Tanahashi Kazuhiro , Mikos Antonios G.
Published: October 2003

We synthesized positively charged biodegradable hydrogels from poly(propylene fumarate‐co‐ethylene glycol) block copolymer and agmatine‐modified poly(ethylene glycol)‐tethered fumarate by radical crosslinking, and investigated the effect of the guanidino group of agmatine on vascular smooth muscle cell adhesion and protein adsorption to the hydrogels. In the presence of serum, the number of adherent smooth muscle cells per unit surface area increased dose‐dependently from 15 to 75% of the initial seeding density at 20 h as the initial agmatine‐modified monomer content increased from 0 to 200 mg/g. Cell spreading also depended on the initial monomer content. In the absence of serum, the number of adherent cells per unit surface area increased slightly from 10 to 17% of the initial seeding density as the initial monomer content increased from 0 to 200 mg/g. Cell adhesion increased significantly by adding exogenous vitronectin to serum‐free medium, whereas exogenous fibronectin addition did not enhance cell adhesion. The enzyme‐linked immunosorbent assay of fibronectin and vitronectin adsorbed onto the hydrogels revealed that the incorporation of positive charges into the hydrogels enhanced vitronectin, but not fibronectin, adsorption significantly. These results suggest that the guanidino group of agmatine enhanced cell adhesion by promoting the adsorption of serum components, and vitronectin may be one of the components. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 448–457, 2003
Modification of Ti6Al4V surfaces using collagen I, III, and fibronectin. I. Biochemical and morphological characteristics of the adsorbed matrix
Authors: Bierbaum Susanne , Beutner René , Hanke Thomas , Scharnweber Dieter , Hempel Ute , Worch Hartmut
Published: October 2003

Studies in developmental and cell biology have established the fact that responses of cells are influenced to a large degree by morphology and composition of the extracellular matrix. Goal of this work is to use this basic principle to improve the biological acceptance of implants by modifying the surfaces with components of the extracellular matrix (ECM). Aiming at load‐bearing applications in bone contact, in this study the modification of titanium surfaces with the collagen types I and III in combination with fibronectin was undertaken; fibrillogenesis, fibril morphology and adsorption of type I, III and I/III‐cofibrils onto titanium were assessed. Increasing the collagen type III amount resulted in a decrease of fibril diameter, while no significant changes in adsorption could be detected. The amount of fibronectin bound to the heterotypic fibrils depended on fibrillogenesis parameters such as ionic strength or concentration of phosphate, and varied with the percentage of integrated type III collagen. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 421–430, 2003
Interactions of heparin with human skin cells: Binding, location, and transdermal penetration
Authors: Parisel Claire , Saffar Line , Gattegno Liliane , André Valérie , Abdul‐Malak Nabil , Perrier Eric , Letourneur Didier
Published: October 2003

The development of new materials for tissue engineering of skin substitutes requires an increasing knowledge of their interactions with human skin cells. Since carbohydrate recognition is involved in numerous biologic processes, including skin regeneration, the aim of this study was to identify sugar receptors expressed at the surface of human dermic and epidermic cells. Binding of fluorescent sugar–polyhydroxyethylacrylamide derivatives was analyzed by flow cytofluorimetry on cultured human skin fibroblasts, keratinocytes, and melanocytes. We observed that these three cell types express a membrane receptor specific for GlcNAc6S. Since the polysaccharide heparin contains this sugar moiety, we further investigated the interactions of heparin with skin cells. We analyzed the in vitro cell binding and ex vivo diffusion with the Franz cell of heparin and of two other polysaccharides of similar molecular weight, dextran and chondroitin sulfate. We found evidence of the preferential binding of heparin on keratinocytes and its high transcutaneous penetration of skin. Altogether, our results describe the affinity of heparin for human skin cells and suggest it may be an excellent candidate for use in the skin delivery of drugs or cosmetics and also as an active component in engineered skin. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 517–523, 2003
Bridging a 30‐mm nerve defect using collagen filaments
Authors: Yoshii Satoru , Oka Masanori , Shima Mitsuhiro , Taniguchi Ataru , Akagi Masao
Published: October 2003

This article describes a 30‐mm regeneration of severed peripheral nerve axons along collagen filaments. Two thousand or 4000 31‐mm‐long collagen filaments were grafted to bridge a 30‐mm defect of the rat sciatic nerve. A collagen tube was grafted as a control. The mean number and mean fiber diameter of regenerated myelinated axons were 330 ± 227 and 2.7 ± 0.9 μm in the distal end of the 2000 collagen‐filaments nerve guide, and 564 ± 275 and 2.5 ± 1.1 μm in the distal end of the 4000 collagen‐filaments nerve guide at 12 weeks postoperatively, whereas in the distal end of the collagen tube, no regenerated axon was found. These results suggest that the collagen filaments guide axons of the rat's sciatic nerve to regenerate for 30 mm and act as a scaffold for axonal regeneration. Thirty‐millimeter nerve regeneration of a 1‐mm‐diameter rat sciatic nerve by an artificial nerve guarantees a clinical application of the implant which should be very important for patients and surgeons. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 467–474, 2003
Structure and properties of the precipitates formed from condensed solutions of the revised simulated body fluid
Authors: Dorozhkina Elena I. , Dorozhkin Sergey V.
Published: October 2003

Precipitation experiments with aqueous solutions of the Kokubo's revised simulated body fluid (rSBF) equal to 2, 4, 8, and 12 times the ionic concentration of human blood plasma were performed. Instead of Hepes, solution pH was adjusted to the desired value of 7.40 ± 0.02 by either bubbling of CO2 or addition of HCl. The experiments were performed in tightly closed plastic vessels kept at 37.0 ± 0.2°C for 72 h under permanent shaking. Afterward, the suspensions were filtrated, and the precipitates were collected and analyzed. The results revealed that increasing the concentration of rSBF resulted in great changes in both the structure and the chemical composition of the precipitates. Phosphate substitution for carbonate (although the amounts of calcium and magnesium remained unchanged) and crystallinity decreasing were the most important modifications found in the precipitates formed from the highly condensed solutions of rSBF. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 578–581, 2003
In vitro cytotoxicity evaluation of a 50.8% NiTi single crystal
Authors: Manceur Aziza , Chellat Fatiha , Merhi Yahye , Chumlyakov Yuriy , Yahia L'Hocine
Published: October 2003

To our knowledge, the biocompatibility of nickel–titanium (NiTi) single crystals has not been reported. Yet certain orientations of single crystals present several advantages over the polycrystalline form in terms of maximal strain, fatigue resistance, and temperature range of superelasticity. Therefore we tested the in vitro biocompatibility of 50.8% NiTi single crystals in the orientation 〈001〉 after four different heat treatments in a helium atmosphere followed by mechanical polishing. The study was performed on the material extracts after immersion of the specimens in cell culture medium (DMEM) for 7 days at 37°C. Cytotoxicity studies were performed on L‐929 mouse fibroblasts using the MTT assay. J‐774 macrophages were used to assess the potential inflammatory effect of the extracts by IL1‐β and TNF‐α dosages (sandwich ELISA method). Exposure of L‐929 to material extracts did not affect cell viability. In addition, IL1‐β and TNF‐α secretion was not stimulated after incubation with NiTi extracts compared to the negative controls. These results were predictable since atomic absorption spectroscopy did not detect nickel ions in the extracts with a resolution of 1 ppm. Within the limits of in vitro testing, our results demonstrate that the TiNi50.8% single crystals do not trigger a cytotoxic reaction. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 641–646, 2003
Direct attachment of fibronectin to tresyl chloride‐activated titanium
Authors: Hayakawa Tohru , Yoshinari Masao , Nemoto Kimiya
Published: October 2003

The aim of this study was to bind fibronectin directly to a titanium surface treated with tresyl chloride (2,2,2‐trifluoroethanesulfonyl chloride) for the development of a strong connection of a dental implant to subepithelial connective tissues and/or peri‐implant epithelia. Basic terminal OH groups of mirror polished titanium were allowed to react with tresyl chloride at 37°C for 2 days. The tresylated titanium disk was then immersed into a fibronectin/phosphate‐buffered saline solution for 24 h at 37°C. The activation reaction of the basic OH of titanium with tresyl chloride was confirmed by S2p, F1s, and O1s spectra using X‐ray photoelectron spectroscopy and OSO2 bonds using Fourier transform infrared reflection‐absorption spectroscopy. After the reaction of fibronectin with titanium, the X‐ray photoelectron spectroscopy revealed the remarkable effect of the activation of terminal OH groups with the tresyl chloride treatment. The N1s peak derived from the attached fibronectin still remained after 60 s of argon‐ion sputtering after tresyl chloride treatment. In contrast, the N1s peak of the specimen not treated with tresyl chloride almost disappeared after only 10 s of argon‐ion etching. Fibronectin, a well‐known cell‐adhesive protein, could easily be attached to the titanium surface by use of the tresyl chloride activation technique. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 684–688, 2003
Transforming growth factor‐β1 in a sterilized tissue derived from the pig small intestine submucosa
Authors: McDevitt Cahir A. , Wildey Gary M. , Cutrone Rochelle M.
Published: October 2003

The extracellular matrices of connective tissues contain growth factors such as transforming growth factor (TGF)‐β1. The possibility arises, therefore, that animal connective tissues that have been excised and rendered acellular in the sterilization, lyophilization, and other preparative processes for human use may still retain active growth factors that could contribute to the clinical efficacy of the product. We therefore analyzed 4M guanidine HCl extracts of a sterilized, acellular matrix, Oasis® Wound Matrix, for the presence of TGF‐β1 by a sandwich enzyme‐linked immunosorbent assay using the soluble type II receptor for TGF‐β to capture the growth factor, and for biological activity by testing the capacity of the extracts to inhibit 3[H]thymidine incorporation into Mv1Lu cells (mink lung epithelial cells). The enzyme‐linked immunosorbent assay determined that TGF‐β1 was present at a concentration of 710.9 ± 157.7 pg/g dry weight of tissue in Oasis® and 768.1 ± 182.1 pg/g dry weight of tissue in SIS (porcine small intestinal submucosa), the disinfected precursor of Oasis®. The growth inhibition assays demonstrated that the Oasis® extracts inhibited the proliferation of Mv1Lu cells in culture, consistent with the TGF‐β1 in the material having biological activity. Most of the TGF‐β1 survives the sterilization and lyophilization processes in the preparation of the Oasis® Wound Matrix, and is functional in its ability to bind to its receptor and, apparently, in its capacity to inhibit growth. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 637–640, 2003
Localized corrosion of 316L stainless steel with SiO2‐CaO films obtained by means of sol–gel treatment
Authors: Vallet‐Regí M. , Izquierdo‐Barba I. , Gil F. J.
Published: October 2003

Sol–gel films on austenitic stainless steel (AISI 316L) polished wafer were prepared from sono‐sols obtained from tetraethylorthosilane and hydrated calcium nitrate. However, pitting was observed in different places on the stainless steel surfaces. The corrosion resistance was evaluated by the polarization resistance in simulated body fluid environment at 37°C. The critical current density, the passive current density, the corrosion potential, and the critical pitting potential were studied. The austenitic stainless steel 316L treated presents important electrochemical corrosion and consequently its application as endosseous implants is not possible. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 674–678, 2003
How to build an adapted and bioactive cell microenvironment? A chemical interaction study of the structure of Ca‐alginate matrices and their repercussion on confined cells
Authors: Bienaimé Christophe , Barbotin Jean‐Noël , Nava‐Saucedo José‐Edmundo
Published: October 2003

Alginates are increasingly being used as medical materials (matrices for tissue regeneration, surgical sponges, hemostatic bandages, microbial and cell encapsulation, artificial bacterial biofilms, etc.). The constitution of alginate gel networks is a complex phenomenon. A great number of different kinds of polysaccharidic frameworks can come to existence depending on the conditions used for their attainment. For instance, the degree of heterogeneity and porosity of Ca‐alginate beads rely on this molecular organization. The formation of structural irregularities (superficial crust, cavities, shafts, dense or light gel frameworks, ordered or chaotic domains, etc.) within the alginate gel beads are inherent to this skeletal design. Several specific staining molecules (e.g. calcon carboxylic acid, murexide, methylene blue) that are negatively or positively charged interact with the gel network. These molecules allowed us to reveal a great variety of chemical interactions shown by the pattern coloration of the internal structure of the gel. The results observed are very different for the several matrices analyzed, which could explain to a great extent the singular behavior that cells confined in these kind of matrices exhibit. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 376–388, 2003
Biologic significance of surface microroughing in bone incorporation of porous bioactive glass implants
Authors: Itälä Ari , Koort Jyri , Ylänen Heimo O. , Hupa Mikko , Aro Hannu T.
Published: October 2003

A novel chemical etching method was recently developed to create a controlled microrough surface on porous bioactive glass implants. Our earlier in vitro studies showed enhanced attachment of osteoblast‐like MG63 cells on a microrough bioactive glass surface. The purpose of our current study was to confirm the in vivo significance of surface microroughening for bone bonding of bioactive glass. Porous bioactive glass cones made of sintered microspheres were surgically implanted in the anterior cortex of rabbit femurs. Peripheral quantitative computed tomography (pQCT), biomechanical push‐out testing, histomorphometry, and electron microscopy (BEI‐SEM) were used to analyze bone ingrowth and osseointegration at 7, 10, 14, 28, 56, and 84 days after implantation. The results showed that microroughening of the bioactive glass surface significantly enhanced the bone‐bonding response of the biomaterial. The positive response was seen in one of the three bioactive glass compositions studied. The affinity index of new bone on the glass surface was significantly (p = 0.02) increased with a trend (p = 0.10) toward improved mechanical incorporation. New bone formation was dependent on the glass composition, and it was found to occur not only through the mechanism of bone ingrowth but also based on in situ osteogenesis within implant interstices. Based on these results, the procedure of microroughening could enhance the osteopromotive properties of certain bioactive glass compositions. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 496–503, 2003
A covering construction for packing disjoint copies of the Hoffman‐Singleton graph into K50
Authors: Ŝiagiová Jana , Meszka Mariusz
Published: October 2003

In this note we show how coverings induced by voltage assignments can be used to produce packings of disjoint copies of the Hoffman‐Singleton graph into K50. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 408–412, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10049
Incomplete group divisible designs with block size four
Authors: Wang J.
Published: October 2003

The object of this paper is the construction of incomplete group divisible designs (IGDDs) with block size four, group‐type (g, h)u and index unity. It is shown that the necessary conditions for the existence of such an IGDD are also sufficient with three exceptions and six possible exceptions. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 442–455, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10055
Resolvable even‐cycle systems with a 1‐rotational automorphism
Authors: Mishima Miwako , Fu Hung‐Lin
Published: October 2003

In this article, necessary and sufficient conditions for the existence of a 1‐rotationally resolvable even‐cycle system of λKvare given, which are eventually for the existence of a resolvable even‐cycle system of λKv. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 394–407, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10058
Covering arrays with mixed alphabet sizes
Authors: Moura Lucia , Stardom John , Stevens Brett , Williams Alan
Published: October 2003

Covering arrays with mixed alphabet sizes, or simplymixed covering arrays, are natural generalizations of covering arrays that are motivated by applications in software and network testing. A (mixed) covering arrayAof type$\prod _{i=1}^{k}g_i$is ak×Narray with the cells of rowifilled with elements from ℤand having the property that for every two rowsiandjand every ordered pair of elements (e,f) ∈ ℤ × ℤ, there exists at least one columnc, 1 ≤ c ≤ N, such thatAi,c = eandAj,c = f. The (mixed) covering array number, denoted by$ca(\prod _{i=1}^{k}g_i)$, is the minimumNfor which a covering array of type$\prod _{i=1}^{k}g_i$withNcolumns exists. In this paper, several constructions for mixed covering arrays are presented, and the mixed covering array numbers are determined for nearly all cases withk = 4 and for a number of cases withk = 5. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 413–432, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10059
Rotational k‐cycle systems of order v < 3k; another proof of the existence of odd cycle systems
Authors: Buratti Marco
Published: October 2003

We give an explicit solution to the existence problem for 1‐rotational k‐cycle systems of order v < 3k with k odd and v ≠ 2k + 1. We also exhibit a 2‐rotational k‐cycle system of order 2k + 1 for any odd k. Thus, for k odd and any admissible v < 3k there exists a 2‐rotational k‐cycle system of order v. This may also be viewed as an alternative proof that the obvious necessary conditions for the existence of odd cycle systems are also sufficient. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 433–441, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10061
Automatic closed‐caption production system on TV programs for hearing‐impaired people
Authors: Monma Takao , Sawamura Eiji , Fukushima Takahiro , Maruyama Ichiro , Ehara Terumasa , Shirai Katsuhiko
Published: October 2003

Increasing the number of closed‐captioned television programs represents a social responsibility in the sense of providing information. In terms of the system to create closed‐captioned television programs by hand, there is considerable hope that the time involved can be reduced and the burden on workers can be eased. The system the authors report on automates three processes in the creation of closed‐captioned television programs: summarization, synchronization, and closed‐captioned screen creation, yielding from an electronic manuscript closed‐caption data applicable to current closed‐captioned broadcasts. The authors created closed captions for 12 types of news programs and one documentary program, confirming that the process of creating a closed‐captioned television program could be completed in three to six times the program length, excluding the process of creating the electronic manuscript and testing/editing. The authors demonstrate the validity of their system insofar as the time needed to create closed captions using their system was about 70% of the time needed to create closed captions by hand, excluding the process of testing and editing. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(13): 71–82, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10047
Progressive early decision of speech recognition results by comparing most likely word sequences
Authors: Imai Toru , Tanaka Hideki , Ando Akio , Isono Haruo
Published: October 2003

The most likely word sequence determined at the end of an utterance constitutes an optimal recognition result in continuous speech recognition for the entire utterance. However, depending on the application, the delay from the utterance to the determination of the recognition result may pose a practical problem, and progressive early decision of recognition results during an utterance becomes necessary. Although in the case of a one‐pass search algorithm, progressive early decision of the recognition result by detecting past sole paths during search is possible, an effective early decision scheme is not available for the case of multiple passes. Thus, a scheme for progressive early decision of recognition results by successively comparing the most likely word sequences during an utterance with the past most likely word sequences is proposed and is applied to a one‐pass decoder and a two‐pass decoder. The proposed scheme attempts to shorten the delays associated with word decisions while limiting the degradation of the recognition rate by controlling the word decision margin and the interval for obtaining the most likely word sequences. In speech recognition experiments of broadcast news, the proposed scheme achieved an average word decision delay equal to that of the past sole path detection method in a one‐pass decoder without significantly degrading the word recognition accuracy, and was able to progressively decide recognition results with an average word decision delay time of about 0.5 second in a two‐pass decoder. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(14): 73–82, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10193
Motion estimation based on eigenvalue algorithm matching local image features
Authors: Kaneko Yutaka , Shishikui Yoshiaki , Tanaka Yutaka
Published: October 2003

We propose a method for motion estimation based on the eigenvalue gradient method with regard for local image features. In the proposed method, motion estimation is first performed by the eigenvalue gradient method, and low‐reliability areas are classified by image features. The estimation accuracy of such areas is improved by using two eigenvalue gradient algorithms. Blocks with multiple motions are processed with robust estimation. On the other hand, blocks with only one gradient are estimated by using a supplementary vector; in particular, the second eigenvector is replaced by the eigenvector of another block from the image area with a common edge. Experimental results show that the proposed method offers improvement of estimation accuracy at a small increase of computational cost. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(14): 63–72, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10292
Use of unlabeled time series data in hidden Markov models
Authors: Inoue Masashi , Ueda Naonori
Published: October 2003

In this paper, the authors propose a method of assigning probabilistic class labels to unlabeled time‐series data that can be collected inexpensively to use together with labeled data as training data in order to improve the performance of hidden Markov models (HMM) as classifiers. Conventional methods of using unlabeled data according to probabilistic class labels were only for static data. They could not deal with time‐series data, which are used with HMMs. Therefore, the authors extended the conventional methods as follows. First, they formed extended tied‐mixture hidden Markov models (ETM‐HMMs) by mixing multiple HMMs that exist independently for each class. Then, they introduced the extended Baum‐Welch (EBW) algorithm as the learning algorithm from time‐series data in which labeled and unlabeled data coexist in the ETM‐HMMs. The authors then assumed a situation in which there existed insufficient labeled training data and used the proposed method to perform classification experiments for Japanese sign language data and voice data. When unlabeled data were added to the labeled training data according to the proposed method, the classification error rate for Japanese sign language signs improved from 38.7% to 30.4%. Also, by making the model more detailed in addition to adding unlabeled data, the classification error rate for phonemes improved from 69.1% to 52.9%. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(13): 1–12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10537
Visual interface from uncalibrated cameras for uncalibrated displays
Authors: Kato Mayumi , Sato Jun
Published: October 2003

A contact‐type interface (such as a mouse or a keyboard) is usually used on personal computers. However, this is not convenient if the operator has to use his or her hands for another operation, or if his or her hands are disabled. To deal with such cases, this paper proposes a visual interface in which the mouse pointer on the computer display is controlled by the movement of the operator's eyes via a camera image. Conventional visual interfaces require tedious calibrations of the camera and system. The proposed visual interface works accurately without any calibration. In the proposed system, the gaze point on the display screen can be reliably calculated from the user's projected image by using projective bases and affine bases and the movement of the user's viewing direction. Control of the mouse pointer by means of the proposed system has been successfully tested. The usefulness of the proposed method has been confirmed. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(13): 83–91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1221
Dictation of multiparty conversation considering speaker individuality and turn taking
Authors: Murai Noriyuki , Kobayashi Tetsunori
Published: October 2003

This paper discusses an algorithm that recognizes multiparty speech with complex turn taking. In recognition of the conversation of multiple speakers, it is necessary to know not only what is spoken, as in the conventional system, but also who spoke up to what point. The purpose of this paper is to find a method to solve this problem. The representation of the likelihood of turn taking is included in the language model in the continuous speech recognition system, and the speech properties of each speaker are represented by a statistical model. Using this approach, two algorithms are proposed that estimate simultaneously and in parallel the speaker and the speech content. Recognition experiments using conversation in TV sports news show that the proposed method can correct a maximum of 29.5% of the errors in the recognition of speech content and 93.0% of the errors in recognition of the speaker. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(13): 103–111, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1223
Differential sensitivity of plant and yeast MRP (ABCC)‐mediated organic anion transport processes towards sulfonylureas
Authors: Forestier Cyrille , Frangne Nathalie , Eggmann Thomas , Klein Markus
Published: October 2003

The role of ATP‐binding cassette (ABC) proteins such as multidrug resistance‐associated proteins (MRPs) is critical in drug resistance in cancer cells and in plant detoxification processes. Due to broad substrate spectra, specific modulators of these proteins are still lacking. Sulfonylureas such as glibenclamide are used to treat non‐insulin‐dependent diabetes since they bind to the sulfonylurea receptor. Glibenclamide also inhibits the cystic fibrosis transmembrane conductance regulator, p‐glycoprotein in animals and guard cell ion channels in plants. To investigate whether this compound is a more general blocker of ABC transporters the sensitivity of ABC‐type transport processes across the vacuolar membrane of plants and yeast towards glibenclamide was evaluated. Glibenclamide inhibits the ATP‐dependent uptake of β‐estradiol 17‐(β‐D‐glucuronide), lucifer yellow CH, and (2′,7′‐bis‐(2‐carboxyethyl)‐5‐(and‐6‐)carboxyfluorescein. Transport of glutathione conjugates into plant but not into yeast vacuoles was drastically reduced by glibenclamide. Thus, irrespective of the homologies between plant, yeast and animal MRP transporters, specific features of plant vacuolar MRPs with regard to sensitivity towards sulfonylureas exist. Glibenclamide could be a useful tool to trap anionic fluorescent indicator dyes in the cytosol.
The protein kinase kin1, the fission yeast orthologue of mammalian MARK/PAR‐1, localises to new cell ends after mitosis and is important for bipolar growth
Authors: Drewes Gerard , Nurse Paul
Published: October 2003

The kin1 protein kinase of the fission yeast Schizosaccharomyces pombe is a member of the PAR‐1/MARK (partitioning‐defective 1/microtubule‐associated protein/microtubule affinity‐regulating kinase) family important in eukaryotic cell polarity and cytoskeletal dynamics. We show here that kin1 plays a role in establishing the characteristic rod‐shaped morphology of fission yeast. Cells in which kin1 was deleted are viable but are impaired in growth, and are rounded at one end or both ends. They are monopolar because after mitosis they fail to activate bipolar growth, and are delayed in cytokinesis, resulting in a high proportion of septated cells often with multiple septa. This phenotype can be partially rescued by heterologous expression of human MARKs, which restore bipolar growth in most cells, but do not correct the delay in cytokinesis. Using chromosomal epitope tagging, we show that kin1p localises to the cell ends, except during mitosis when it disappears from cell ends. After mitosis, kin1p first reappears at the new cell end. Overexpression of kin1 results in a loss of polarity, with partially or fully rounded cells. From these results we suggest that kin1 is required to direct the growth machinery to the cell ends.
A cytochrome c oxidase proton pumping mechanism that excludes the O2 reduction site
Authors: Yoshikawa Shinya
Published: October 2003

A redox‐coupled conformational change in Asp51 of subunit I and a hydrogen‐bond network connecting Asp51 with the matrix surface have been deduced from X‐ray structures of bovine heart cytochrome c oxidase. This has provided evidence that Asp51 may play a role in the proton pumping process. However, the lack of complete conservation of a residue analogous to Asp51, the inclusion of a peptide bond in the hydrogen‐bonding network and the lack of apparent involvement of the O2 reduction site have been used as arguments against the involvement of Asp51 in the mechanism of proton pumping. This minireview re‐examines these arguments.
Wolinella succinogenes quinol:fumarate reductase and its comparison to E. coli succinate:quinone reductase
Authors: Lancaster C.Roy D
Published: October 2003

The three‐dimensional structure of Wolinella succinogenes quinol:fumarate reductase (QFR), a dihaem‐containing member of the superfamily of succinate:quinone oxidoreductases (SQOR), has been determined at 2.2 Å resolution by X‐ray crystallography [Lancaster et al., Nature 402 (1999) 377–385]. The structure and mechanism of W. succinogenes QFR and their relevance to the SQOR superfamily have recently been reviewed [Lancaster, Adv. Protein Chem. 63 (2003) 131–149]. Here, a comparison is presented of W. succinogenes QFR to the recently determined structure of the mono‐haem containing succinate:quinone reductase from Escherichia coli [Yankovskaya et al., Science 299 (2003) 700–704]. In spite of differences in polypeptide and haem composition, the overall topology of the membrane anchors and their relative orientation to the conserved hydrophilic subunits is strikingly similar. A major difference is the lack of any evidence for a ‘proximal’ quinone site, close to the hydrophilic subunits, in W. succinogenes QFR.
The ubiquitin–protein ligase activity of Hdm2 is inhibited by nucleic acids
Authors: Linares Laëtitia K , Scheffner Martin
Published: October 2003

The proto‐oncoprotein Hdm2 is a member of the RING finger‐type family of ubiquitin–protein ligases E3. The RING finger domain is assumed to mediate the specific interaction of an E3 with its cognate ubiquitin‐conjugating enzyme E2, which catalyzes the covalent attachment of ubiquitin to substrate proteins. In addition, the RING finger domain of Hdm2 is involved in Hdm2 homooligomer formation and has the capacity to bind to RNA in a sequence‐specific manner. Here we report that interaction with nucleic acids interferes with both Hdm2/Hdm2 complex formation and auto‐ubiquitination of Hdm2 in vitro. Furthermore, although binding of Hdm2 to the tumor suppressor p53 is not inhibited by nucleic acids, Hdm2‐mediated ubiquitination of p53 is significantly decreased. Taken together, these results provide the first example of an E3 whose activity can be regulated by direct interaction with nucleic acids.