bluuebunny/crossref_metadata_2025 huggingface dataset:
Sun exposure predicts risk of ocular melanoma in Australia
Authors: Vajdic Claire M. , Kricker Anne , Giblin Michael , McKenzie John , Aitken Joanne , Giles Graham G. , Armstrong Bruce K.
Published: September 2002

Previous studies examining sun exposure and ocular melanoma have produced inconsistent results. We investigated this association in a population‐based case‐control study in Australia. Cases (n = 290) aged 18–79 years were diagnosed between January 1996 and July 1998. Controls (n = 893) were randomly selected from the electoral rolls and frequency‐matched to cases by age, sex and state. A self‐administered questionnaire and a telephone interview measured sun exposure on weekdays and weekends at 10, 20, 30 and 40 years of age and over the whole of life for specific jobs and recreations. Multivariate logistic regression models of ocular melanoma and sun exposure contained age, sex, region of birth, eye color and measures of ocular and cutaneous sun sensitivity as covariates. Choroid and ciliary body melanoma (n = 246) was positively associated with time outdoors on weekdays and, less persuasively, total time outdoors but not ambient solar irradiance. Odds ratios increased with increasing exposure to OR 1.8 (95% confidence interval 1.1–2.8) for the highest quarter of sun exposure on weekdays up to 40 years of age for men and women together. The strongest positive associations were for total exposure up to 40 years of age, lifetime occupational exposure and total exposure at about 20 years of age in men; all had odds ratios between 2 and 3 in the highest exposure categories. There was inconclusive evidence for an association between sun exposure and iris (n = 25) or conjunctival (n = 19) melanomas. Sun exposure is an independent risk factor for choroidal and ciliary body melanoma in Australia. © 2002 Wiley‐Liss, Inc.
Cancer‐testis antigen expression in uterine malignancies with an emphasis on carcinosarcomas and papillary serous carcinomas
Authors: Resnick Murray B. , Sabo Edmond , Kondratev Svetlana , Kerner Hedviga , Spagnoli Giulio C. , Yakirevich Evgeny
Published: September 2002

The cancer testis (CT) family of antigens are expressed in certain malignant neoplasms and are silent in normal adult tissues, except for the testis. Expression of 2 members of this family, MAGE‐A4 and NY‐ESO‐1, has been described recently in germ cell tumors, malignant melanomas, certain carcinomas and sarcomas. Our study is the first to describe the expression pattern of CT antigens in uterine neoplasms. Ninety‐eight cases of uterine neoplasms, including 41 endometrioid, 19 papillary serous and 7 clear cell carcinomas, 22 carcinosarcomas and 9 endometrial stromal sarcomas were studied. Immunohistochemistry was carried out with the 57B monoclonal antibody that recognizes predominantly the MAGE‐A4 antigen in paraffinized tissues and the D8.38 antibody that recognizes NY‐ESO‐1. MAGE‐A4 expression was found to be present in 12% of the endometrioid adenocarcinomas, 63% of the papillary serous carcinomas and 91% of the carcinosarcomas. Within the tumor population the extent of MAGE‐A4 expression was highest in the carcinosarcomas. In 12 of 22 positively staining carcinosarcomas more than 50% of the tumor cells expressed MAGE‐A4. NY‐ESO‐1 expression was seen in 19% of the endometrioid adenocarcinomas, 32% of the papillary serous carcinomas and in 45% of the carcinosarcomas. CT antigen immunoreactivity was observed in both the carcinomatous and sarcomatous components of the carcinosarcomas and strong correlation between MAGE‐A4 and NY‐ESO‐1 expression was present in individual cases. In summary, strong MAGE‐A4 expression and to a lesser degree NY‐ESO‐1 expression is characteristic of the vast majority of uterine carcinosarcomas and a major subset of papillary serous carcinomas. These results suggest that CT antigen expression by these tumors may represent a novel target for immunotherapy. © 2002 Wiley‐Liss, Inc.
The most appropriate (Ca+Zn)/P molar ratio to minimize the zinc content of ZnTCP/HAP ceramic used in the promotion of bone formation
Authors: Sogo Yu , Sakurai Tokoha , Onuma Kazuo , Ito Atsuo
Published: September 2002

The (Ca+Zn)/P molar ratio of zinc‐containing tricalcium phosphate and hydroxyapatite composite ceramics (ZnTCP/HAP) was investigated in the range from 1.50 to 1.66 to reveal the minimum zinc content possible in ceramics used in the promotion of osteoblastic cell proliferation and bone formation. The release rate of zinc increased with an increase in the (Ca+Zn)/P molar ratio up to 1.64 (ZnTCP/HAP1.64) and then decreased over 1.64 even when the zinc content of ZnTCP/HAP was the same. The zinc release rate of ZnTCP/HAP1.64 with a 0.21 Zn wt % nearly coincided with that of ZnTCP/HAP1.60 with a 0.316 Zn wt %, which was found be the most effective for promoting bone formation in rabbit femora. This means that the zinc content needed to promote bone formation can be reduced by 34% when the (Ca+Zn)/P molar ratio is increased to 1.64. The relative growth rate of MC3T3‐E1 cells cultured on ZnTCP/HAP1.64 had a maximum value of 1.3 at a zinc content of 0.51 wt %; however, a 1.20 Zn wt % is required to attain the same value in relative growth rate in the case of ZnTCP/HAP1.60. A reduction in zinc content at a certain zinc release rate results from an increase in zinc content of the ZnTCP phase in ZnTCP/HAP. The ZnTCP/HAP1.64 would be better than any other ZnTCP/HAP relative to material safety because the risk of an accidental burst of zinc from the material is minimized due to the low zinc content. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 457–463, 2002
Optimization of monomethoxy‐polyethylene glycol grafting on the pancreatic islet capsules
Authors: Lee Dong Yun , Yang Kyungwook , Lee Sangjun , Chae Su Young , Kim Kwang‐Won , Lee Moon Kyu , Han Duck‐Jong , Byun Youngro
Published: September 2002

As a new approach to islet transplantation, biocompatible monomethoxy‐poly(ethylene glycol) (mPEG) was chemically grafted onto the pancreatic islet capsule. The aim of this study was to determine the optimal conditions for completely covering the islet by the mPEG while maintaining a high viability of islets according to the reaction time and the repeating number of the reaction. By grafting the fluorescein‐PEG instead of mPEG, we determined the optimal mPEG grafting time as 1 h, during which time the procedure did not reduce islet viability. Insulin secretion from islets where the mPEG was grafted on for 3 times was similar to that of control islets. Moreover, the mPEG‐grafted islets rapidly responded to the changes in the glucose concentration in the same pattern as did control islets. These results showed that mPEG grafting did not damage the function of islets. In conclusion, when the mPEG grafting was performed for 1 h and repeated twice with 1‐day culture between each mPEG‐grafting step, the mPEG completely covered the islet capsules without any damage to the viability and function of the islets. The main advantage of mPEG grafting on the islet capsule is that it can protect the islet against the host's immune system without increasing the islet size so that it can be administered into the portal vein by the catheter. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62:372–377, 2002
Characterization of microrough bioactive glass surface: Surface reactions and osteoblast responses in vitro
Authors: Itälä A. , Ylänen H. O. , Yrjans J. , Heino T. , Hentunen T. , Hupa M. , Aro H. T.
Published: September 2002

The current study characterized the in vitro surface reactions of microroughened bioactive glasses and compared osteoblast cell responses between smooth and microrough surfaces. Three different bioactive glass compositions were used and surface microroughening was obtained using a novel chemical etching method. Porous bioactive glass specimens made of sintered microspheres were immersed in simulated body fluid (SBF) or Tris solutions for 1, 6, 24, 48, or 72 h, and the formation of reaction layers was studied by means of a scanning electron microscope/energy dispersive X‐ray analysis (SEM/EDXA). Cell culture studies were performed on bioactive glass disks to examine the influence of surface microroughness on the attachment and proliferation of human osteoblast‐like cells (MG‐63). Cell attachment was evaluated by means of microscopic counting of in situ stained cells. Cell proliferation was analyzed with a nonradioactive cell proliferation assay combined with in situ staining and laser confocal microscopy. The microroughening of the bioactive glass surface increased the rate of the silica gel layer formation during the first hours of the immersion. The formation of calcium phosphate layer was equal between control and microroughened glass surfaces. In cell cultures on bioactive glass, the microrough surface enhanced the attachment of osteoblast‐like cells but did not have an effect on the proliferation rate or morphology of the cells as compared with smooth glass surface. In conclusion, microroughening significantly accelerated the early formation of surface reactions on three bioactive glasses and had a positive effect on initial cell attachment. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 404–411, 2002
An investigation of the cytotoxicity and histocompatibility of in situ forming lactic acid based orthopedic biomaterials
Authors: Burdick Jason A. , Padera Robert F. , Huang Janice V. , Anseth Kristi S.
Published: September 2002

The cytotoxicity and biocompatibility of polymer networks prefabricated from multifunctional lactic acid based oligomers that are being developed for orthopedic applications were assessed through in vitro cytotoxicity analysis and subcutaneous implantation. After 7 and 14 days, no significant difference was observed in the relative viability or alkaline phosphatase activity of primary rat calvarial osteoblasts cultured in the presence or absence of degrading polymer networks, indicating that the degradation products had no detrimental effect on the function or activity of the cultured cells. The tissue response to preformed lactic acid networks implanted in rats consisted of a mild inflammatory response with an increase in fibrous capsule thickness and inflammation correlating with faster degrading polymer compositions. This relatively neutral response is indicative of a biocompatible, degradable polymer that has potential medical applications. Finally, porous scaffolds were implanted subcutaneously in rats, and vascularized fibrous tissue infiltration was highly dependent on the scaffold porosity and architecture. This finding indicates that an in situ forming porous scaffold of this composition may support the infiltration of surrounding vascularized tissue, and thus be applicable to orthopedic treatments of large bone defects. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 484–491, 2002
Ion release in patients with metal‐on‐metal hip bearings in total joint replacement: A comparison with metal‐on‐polyethylene bearings
Authors: Savarino L. , Granchi D. , Ciapetti G. , Cenni E. , Nardi Pantoli A. , Rotini R. , Veronesi C.A. , Baldini N. , Giunti A.
Published: September 2002

Polyethylene (PE) wear has been shown to be a problem in long‐term joint replacement using metal‐on‐PE bearing. The use of metallic heads articulating with metallic cups could solve this problem: success will be enhanced if wear and corrosion of the articulating surfaces are maintained at a low level. New models with metal‐on‐metal bearing have been proposed, to be used mainly for young subjects: such coupling seems to have a reduced release, but it is unclear yet if the medium‐term corrosion rate is really negligible or, on the contrary, it is significantly higher than in the metal‐on‐PE bearing. Aim of our study was the comparison of ion release in the serum of two groups of patients who had the same type of stable cementless prosthesis, but different bearing: twenty‐six patients with metal‐on‐metal (Group A) and fifteen patients with metal‐on‐PE bearing (Group B) were examined. The follow‐up was 14‐38 months for group A and 18‐34 months for group B. The serum concentration of chromium (Cr), cobalt (Co) and molybdenum (Mo) was measured. Twenty‐two patients before surgery were used for comparison (Group C). The reference values were obtained from a population of twenty‐two healthy subjects (Group D). Our findings indicate that metal‐on‐metal bearings produce a significantly higher systemic release of cobalt and chromium (ng/ml) when compared with levels found in metal‐on‐PE, pre‐surgery and reference groups. Such a high release should induce to improve the bearing materials or, at least, to study the biologic fate of metal ions and consequently their long‐term effects. In such a way a risk‐to‐benefit ratio for the patient could be established. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 467–474, 2002
Standardized analysis of UHMWPE wear particles from failed total joint arthroplasties
Authors: Mabrey Jay D. , Afsar‐Keshmiri Armin , Engh Gerard A. , Sychterz Christi J. , Wirth Michael A. , Rockwood Charles A. , Agrawal C. Mauli
Published: September 2002

Periprosthetic tissue obtained at revision surgery from eight total hip replacement cases was hydrolyzed, and polyethylene debris particles were isolated from each case. Individual particles were analyzed by scanning electron microscopy (SEM) and computerized image analysis in accordance with ASTM F1877‐98, a standard for quantitative description of wear debris. For comparison, periprosthetic tissues from eight total knee revision and four total shoulder revision cases were processed and analyzed with identical methods. A total of 2599 hip, 4345 knee, and 1200 shoulder particles were analyzed. The morphologies of the isolated polyethylene particles from the total hip specimens were distinctly different from the total knee and total shoulder particles. The mean equivalent circle diameter (ECD) for hip particles was 0.694 μm ± 0.005; knee particles measured 1.190 μm ±0.009; and shoulder particles 1.183 μm ± 0.017. The ECD was significantly different between hip particles and those from the shoulder and knee. The mean aspect ratio (AR) for the hip particles was 1.626 ± 0.015, compared to the knee particles at 1.935 ± 0.015 and shoulder particles at 2.082 ± 0.033. The AR was statistically different among all three groups. Other descriptors from the ASTM standard, elongation (E), form factor (FF), and roundness (R) were all significantly different among the three groups of joints. This study demonstrates the utility of ASTM F1877‐98 in differentiating wear debris particles from different sources. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 475–483, 2002
Effect of water treatment on the apatite‐forming ability of NaOH‐treated titanium metal
Authors: Uchida Masaki , Kim Hyun‐Min , Kokubo Tadashi , Fujibayashi Shunsuke , Nakamura Takashi
Published: September 2002

NaOH and heat treatments of titanium metal induce an apatite‐forming ability on the metal by producing a bioactive graded sodium titanate structure on its surface. An enhancement of the apatite‐forming ability of titanium metal induced by the NaOH treatment was attempted by conjoining the water and heat treatments. These treatments are assumed to convert the sodium titanate into anatase, which is presumed to be more effective for apatite nucleation. The sodium titanate gel on the metal formed from the NaOH treatment was shown to transform into anatase by a simple immersion in pure water, with subsequent heat treatments. Forming anatase on the metal significantly improved the apatite‐forming ability of the metal in a simulated body fluid (SBF). The apatite‐forming ability correlated directly with the amount of anatase on the metal. It is therefore expected that bioactive titanium metal and its alloys with a higher bone‐bonding ability can be obtained with the use of the water and subsequent heat treatments after the NaOH treatment. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 522–530, 2002
Implantation study of a novel hydroxyapatite/collagen (HAp/col) composite into weight‐bearing sites of dogs
Authors: Itoh Soichiro , Kikuchi Masanori , Takakuda Kazuo , Nagaoka Katsuyoshi , Koyama Yoshihisa , Tanaka Junzo , Shinomiya Kenichi
Published: September 2002

A hydroxyapatite/type I collagen (HAp/Col) composite, aligning hydroxyapatite nanocrystals along collagen molecules, has been prepared. The biocompatibility, osteoconductive activity, and efficacy as a carrier of rhBMP‐2 of this novel biomaterial implanted in the weight‐bearing site have been examined. The HAp/Col implants (15 mm in diameter and 20 mm in length) with a surface cross‐linked layer containing rhBMP‐2 (0 or 400 μg/ml) were implanted into bone defects of tibiae in three beagle dogs and fixed according to the Ilizarov method. As a control, bone defects of 20 mm in two beagle dogs did not receive implants, and the dogs were allowed to walk using an Ilizarov extraskeletal fixator. The specimens were removed from one dog in each group after 12 weeks. Also, the Ilizarov fixators in the rhBMP‐treated dogs were removed after 12 weeks, after which full weight bearing started. The specimens were further taken out after 18 and 24 weeks in the rhBMP‐treated and non‐rhBMP‐treated dogs, and after 24 weeks in the control group. The change of bone mineral density, as well as radiological and histological findings, suggest that the implants are able to induce bone remodeling units and are a superior carrier of rhBMP‐2 due to the stimulation of early callus and new bone formation. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 507–515, 2002
Characteristics and porcelain bond strength of (Ti,Al)N coating on dental alloys
Authors: Chung Kwok‐Hung , Duh Jeng‐Gong , Shin Daehwan , Cagna David R. , Cronin Robert J.
Published: September 2002

The effect of a novel titanium–aluminum nitride film, or (Ti,Al)N film, on the bond strength between a dental porcelain and two nickel‐based dental alloy substrates was investigated. A thin layer of (Ti,Al)N film was deposited on flat metal samples using a reactive radio‐frequency sputtering method. A uniform thickness of porcelain was applied to the film‐ coated metal samples. Metal–ceramic specimens were subjected to three‐point bending, and failure loads were recorded. Bond strengths between the porcelain and (Ti,Al)N‐coated metal alloys ranged from 159.0 ± 11.7 N to 278.0 ± 12.3 N. These values were significantly greater (p< 0.05) than bond strengths recorded for control samples that did not incorporate the (Ti,Al)N film. An electron probe microanalyzer with a line profile mode was used to characterize the interface between the (Ti,Al)N film and the porcelain. Results of this investigation suggest that the (Ti,Al)N film (1) increases the flexural bond strength between dental porcelain and nickel‐based alloy substrates by permitting elemental diffusion, (2) interferes with the surface oxide formation that characteristically originates from the nickel‐based metal alloy substrate, and (3) provides an appropriate oxide layer for porcelain application. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 516–521, 2002
Calcium phosphate/chitosan composite scaffolds for controlled in vitro antibiotic drug release
Authors: Zhang Yong , Zhang Miqin
Published: September 2002

Macroporous chitosan scaffolds reinforced by β‐tricalcium phosphate (β‐TCP) and calcium phosphate invert glasses were fabricated using a thermally induced phase separation technique. These porous composite materials were specially designed as both a drug carrier for controlled drug release and a scaffold for bone regeneration. The controlled drug release of antibiotic gentamicin‐sulfate (GS) loaded scaffolds and morphology of osteosarcoma MG63 cells cultured on the scaffolds were studied. In comparison with the GS loaded pure chitosan scaffolds, the initial burst release of GS was decreased through incorporating calcium phosphate crystals and glasses into the scaffolds, and the sustained release for more than 3 weeks was achieved. The possible mechanisms for the controlled drug release were investigated by SEM, FTIR, and measurements of the pH values of the PBS solution during the drug release test. SEM micrographs showed no apparent morphological differences for osteoblastic cells grown on the pure chitosan scaffolds and those grown on composite scaffolds. The cells were attached and migrated on these scaffolds, and exhibited a biological appearance, suggesting a good cellular compatibility. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 378–386, 2002
Characterization of implant materials in fetal bovine serum and sodium sulfate by electrochemical impedance spectroscopy. I. Mechanically polished samples
Authors: Contu F. , Elsener B. , Böhni H.
Published: September 2002

Electrochemical impedance spectroscopy is used to monitor the long‐term stability (up to 150 days) of mechanically polished commercial pure titanium, Ti6Al4V, Ti6Al7Nb, and CoCrMo alloys in 0.1M sodium sulfate and fetal bovine serum. A capacitive spectrum in the frequency range from 10−3 to 105 Hz is always found and the impedance spectra can be fitted by a simple parallel RC circuit with a constant phase element. The open circuit potential observed in serum is always more cathodic and the polarization resistance (Rp) is higher than that recorded in sodium sulfate solutions. The observed variation of the equivalent capacitance in serum bovine suggests that an adsorption layer of organic molecules develops on the electrode surface and it is responsible for both the decrease in open circuit potential and the higher Rp, because it hinders the oxygen evolution reaction and the charge transfer responsible for the passive film dissolution (or growth). Among the alloys studied, Ti6Al4V displayed the highest steady‐state values of Rp both in serum and in sodium sulfate. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 412–421, 2002
Human monocyte response to retrieved polymethylmethacrylate particles
Authors: Miyaguchi Masatsugu , Kobayashi Akio , Iwaki Hiroyoshi , Ohashi Hirotsugu , Kadoya Yoshinori , Yamano Yoshiki
Published: September 2002

The purpose of this study was to compare retrieved polymethylmethacrylate (PMMA) particles from failed total hip arthroplasties in terms of size, shape, and the response of human monocytes with commercially available particles. PMMA particles were isolated from peri‐implant tissues of five failed cemented total hip arthroplasties using tissue digestion and a sucrose density gradient technique. Prepolymerized cement powder and those from which barium sulfate had been removed were examined for comparison. After exposure of peripheral human monocytes to PMMA particles, tumor necrosis factor‐α and interleukin‐6 in medium were measured by using enzyme‐linked immunosorbent assays. Image analysis revealed that retrieved particles were larger (retrieved: 1.24 μm; prepolymerized cement powder: 0.83 μm; barium sulfate‐free powder: 0.87 μm) and were more irregular in shape and rougher than commercially available particles. Cytokine release was increased by all PMMA particle species. However, commercially available PMMA particles stimulated the release of necrosis factor‐α and interleukin‐6 more strongly than did retrieved particles at very high doses. The observed difference in monocyte response might be due to the volume of the challenged particles. Another possible reason for the difference might be alteration of the surface chemistry of particles in situ and the difference in surface morphology between them. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 331–337, 2002
Gamma irradiation alters fatigue‐crack behavior and fracture toughness in 1900H and GUR 1050 UHMWPE
Authors: Cole Jantzen C. , Lemons Jack E. , Eberhardt Alan W.
Published: September 2002

Pitting and delamination remain causative factors of polyethylene failure in total knee replacement. Gamma irradiation induces cross linking in ultra‐high‐molecular‐weight polyethylene, which has been shown to improve wear resistance. Irradiation may reduce fracture toughness and fatigue strength, however, and the effects of irradiation are dependent upon the resin, processing technique, and radiation dose. The effects of varying levels of gamma irradiation (0, 33, 66, and 100 kGy) on the fracture toughness and fatigue‐crack resistance of UHMWPE, isostatically molded from 1900H and GUR 1050 resins, were examined. Paris law regressions were performed to quantify fatigue‐crack propagation rates as functions of change in stress intensity, and J‐integral methods were used to quantify the elastic–plastic fracture toughness. The results indicated that gamma irradiation reduced the resistance of both materials to fatigue‐crack growth, and that the reductions were radiation dosage and resin dependent. Irradiation at any level was detrimental to the fracture toughness of the 1900H specimens. Irradiation at 33 kGy increased fracture toughness for the GUR 1050 specimens, and substantial reductions were observed only at the highest irradiation level. Scanning electron microscopy of the fracture surface revealed diamond‐like fracture patterns of the nonirradiated specimens indicative of ductile, multilevel fracture. Pronounced striations were apparent on these fracture surfaces, oriented perpendicular to the direction of crack growth. The striations appeared as folds in surface layers of the GUR 1050 specimens. At the highest irradiation levels, the striations were nearly eliminated on the fracture surfaces of the 1900H specimens, and were markedly less severe for the GUR 1050. These results demonstrated that at higher irradiation levels the materials became more brittle in fatigue, with less ductile folding and tearing of the fracture surfaces. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 559–566, 2002
The peak‐amplitude method of vibration analysis for nondestructively studying the structural integrity of dental gypsum
Authors: Prombonas Anthony E. , Paralika Maria A. , Sotiriou Michael P. , Vlissidis Dimitris S.
Published: September 2002

The aim of this work was to estimate the internal friction of dental gypsum products by measuring their loss factor with the use of the peak‐amplitude method of vibration analysis. Cylindrical specimens for the measurement of compressive strength and rectangular specimens for the measurement of loss factor were constructed from plaster, dental stone, and high‐strength dental stone. The loss factor was measured by vibrating specimens up to their resonance frequency, where the peak‐amplitude method was applied. It was found that the peak‐amplitude method is a simple, quick, and reliable method for measuring the loss factor of dental gypsum products. Furthermore, it was also found that the drying process of these materials reduces their internal friction and hence lowers the loss factor, whereas the use of excess water in their formulation has the reverse result. The correlation between strength and loss factor was found to be strongly negative. The results of this study are in agreement with the results from research on the microstructure of dental gypsum. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 605–609, 2002
The electrochemical behavior of Ti‐6Al‐7Nb alloy with and without plasma‐sprayed hydroxyapatite coating in Hank's solution
Authors: Lavos‐Valereto I. C. , Costa I. , Wolynec S.
Published: September 2002

The electrochemical behavior of Ti‐6Al‐7Nb alloy with and without plasma‐sprayed hydroxyapatite (HA) coating was investigated in Hank's balanced salt solution at 37 °C. This behavior was evaluated by analyzing both corrosion potential variation with time curves and potentiodynamic polarization curves. The polarization curves were determined both in aerated and deaerated solutions. It was found that the corrosion potential of uncoated sample is always more noble than that of coated one. In aerated solutions the polarization curve of a coating‐free alloy presents a typical passive/transpassive behavior, which is absent in the HA‐coated alloy and in deaerated solution for both coated and uncoated conditions. In the latter polarization curves, the current density continuously increases with the increase of the potential. The corrosion rate determined from polarization curves is higher for HA‐coated alloys, but it still can be considered negligible (less than 1 μA/cm2). © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 664–670, 2002
Adhesive phase separation at the dentin interface under wet bonding conditions
Authors: Spencer Paulette , Wang Yong
Published: September 2002

Under in vivo conditions, there is little control over the amount of water left on the tooth and, thus, there is the danger of leaving the dentin surface so wet that the bonding resin undergoes physical separation into hydrophobic and hydrophilic‐rich phases. The purpose of this study was to investigate phase separation in 2,2‐bis[4(2‐hydroxy‐3‐methacryloyloxy‐propyloxy)‐phenyl] propane (BisGMA)‐based adhesive using molecular microanalysis and to examine the effect of phase separation on the structural characteristics of the hybrid layer. Model BisGMA/HEMA (hydroxyethl methacrylate) mixtures with/without ethanol and commercial BisGMA‐based adhesive (Single Bond) were combined with water at concentrations from 0 to 50 vol%. Macrophase separation in the BisGMA/HEMA/water mixtures was detected using cloud point measurements. In parallel with these measurements, the BisGMA/HEMA and adhesive/water mixtures were cast as films and polymerized. Molecular structure was recorded from the distinct features in the phase‐separated adhesive using confocal Raman microspectroscopy (CRM). Human dentin specimens treated with Single Bond were analyzed with scanning electron microscopy (SEM) and CRM mapping across the dentin/adhesive interface. The model BisGMA/HEMA mixtures with ethanol and the commercial BisGMA‐based adhesive experienced phase separation at ∼25 vol% water. Raman spectra collected from the phase‐separated adhesive indicated that the composition of the particles and surrounding matrix material was primarily BisGMA and HEMA, respectively. Based on SEM analysis, there was substantial porosity at the adhesive interface with dentin. Micro‐Raman spectral analysis of the dentin/adhesive interface indicates that the contribution from the BisGMA component decreases by nearly 50% within the first micrometer. The morphologic results in corroboration with the spectroscopic data suggest that as a result of adhesive phase separation the hybrid layer is not an impervious 3‐dimensional collagen/polymer network but a porous web characterized by hydrophobic BisGMA‐rich particles distributed in a hydrophilic HEMA‐rich matrix. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 447–456, 2002
Histological examination of β‐tricalcium phosphate graft in human femur
Authors: Ogose Akira , Hotta Tetsuo , Hatano Hiroshi , Kawashima Hiroyuki , Tokunaga Kunihiko , Endo Naoto , Umezu Hajime
Published: September 2002

Prominent osteoconductive activity and the biodegradable nature of beta tricalcium phosphate (β‐TCP) for bone grafts in animal experiments has been reported. A new type of β‐TCP has been manufactured at extraordinarily high purity and has been available as potent bone grafting substitute for clinical use. The histological features of grafted β‐TCP in human bone have been analyzed. A 33‐year‐old female with a bone tumor of the proximal femur underwent curettage and β‐TCP graft under the diagnosis of probable benign fibrous dysplasia. Four weeks later, the proximal femur, including the grafted β‐TCP was resected because of the final diagnosis of the curettaged materials was osteosarcoma. The resected specimen revealed abundant direct new bone apposition on β‐TCP. There was no cartilaginous tissue or enchondral ossification. Bone formation was more prominent in the periphery of the grafted area than in the center. There was a considerable number of osteoclast‐like giant cells surrounding the β‐TCP. This case illustrated that highly purified β‐TCP had prominent osteoconductive activity and biodegradable nature in human bone. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 601–604, 2002
Chitosan‐alginate PEC membrane as a wound dressing: Assessment of incisional wound healing
Authors: Wang Lishan , Khor Eugene , Wee Aileen , Lim Lee Yong
Published: September 2002

Flexible, thin, transparent, novel chitosan‐alginate polyelectrolyte complex (PEC) membranes, cast from aqueous suspensions of chitosan‐alginate coacervates with CaCl2, were evaluated as potential wound‐dressing materials. MTT and NR assays suggested that the chitosan‐alginate PEC membranes and their aqueous extracts were nontoxic towards mouse and human fibroblast cells. Cell growth was also not hindered by co‐incubation with the membranes. Compared to conventional gauze dressing, the PEC membranes caused an accelerated healing of incision wounds in a rat model. Wounds closed at 14 days postoperatively, and histological observations showed mature epidermal architecture with keratinized surface of normal thickness and a subsided inflammation in the dermis. This was followed by an excellent remodeling phase with organized thicker collagen bundles and mature fibroblasts at 21 days postoperative. Control wounds continued to show signs of an active inflammatory phase under scab on Day 21. Closure rate and appearance of PEC membrane‐treated wounds were comparable with Opsite®‐treated wounds. On the basis of its biocompatibility and wound‐healing efficacy, the chitosan‐alginate PEC membrane can be considered for wound‐dressing applications. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 610–618, 2002
Cytotoxicity of ingredients of various dental materials and related compounds in L2‐ and A549 cells
Authors: Walther U. I. , Walther S. C. , Liebl B. , Reichl F. X. , Kehe K. , Nilius M. , Hickel R.
Published: September 2002

Various ingredients of dental materials and related compounds were tested for cytotoxicity in two alveolar epithelial cell lines (L2 and A549 cells). Release of lactate dehydrogenase (LDH) from cells was measured after incubation with the test substances for time intervals up to 48 h and expressed as percentage of total LDH content of lysed cells. Furthermore, the glutathione content of cells was determined in the nonmalignant L2 cells. Additionally, cell viability was assessed by microscopic examination. The highest cytotoxicity was observed with mercury compounds (methylmercuric chloride and mercury dichloride) in the range of 5–20 μmol/l. The composite components 2‐hydroxyethylmethacrylate (HEMA) and triethleneglycoldimethacrylate (TEGDMA) showed time‐ and concentration‐dependent effects of cytotoxicity at high concentrations (about 1–5 mmol/l). A time dependence for GSH decrease was mainly found for the composite components up to 12 h of cellular exposure. L2 cells were more sensitive to both mercury and composite compounds than A549 cells. Gold compounds (sodiumaurothiomalate and gold particles < 1.5 μm) did not produce any sign of toxic reactions. A time‐dependent increased toxicity in pulmonary cell lines was found for the composite components HEMA and TEGDMA, but not for mercury and gold compounds. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 643–649, 2002
The influence of system compliance and sample geometry on composite polymerization shrinkage stress
Authors: Laughlin Gayle A. , Williams John L. , Eick J. David
Published: September 2002

The objective of this study was to use finite‐element analysis to model tensilometer tests of polymerizing dental composites. A typical sample in polymerization shrinkage stress tests is shaped like a flat disk, that is, has a high aspect ratio (ratio of diameter to height). In the experimental literature it is implied that the induced stress state in the flat disk composite samples is uniaxial. Three published tensilometer tests of curing dental composite samples with similar high aspect ratios (varying from 3 to 5) were modeled, but with test configurations having low, intermediate and high relative compliance (a tenfold variation). With the use of linear elastic finite element analysis, an instantaneous volumetric shrinkage of 1% was applied to the composite via the thermal analogy and the following questions were addressed:

Does the numerically predicted state of stress in composite samples tested in this fashion differ substantially from the uniaxial stress state assumed in the experiments?

How do the numerically predicted stresses compare with the experimentally determined nominal stresses?

Does compliance of the mountings influence the numerically predicted stress state?

The finite‐element results predicted a complex triaxial stress state that was strongly influenced by the compliance of the mountings. For the low and intermediate system compliance the model overpredicted the polymerization contraction stress, as would be anticipated due to the inability of the model to account for viscoplastic flow. For high system compliance, the numerical and experimental stress values were in better agreement, mainly because the linear elastic mountings accounted for most of the measured system compliance. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 671–678, 2002
Morphological changes induced by extracellular matrix are correlated with maturation of rat small hepatocytes
Authors: Sugimoto Shinichi , Mitaka Toshihiro , Ikeda Shinichiro , Harada Keisuke , Ikai Iwao , Yamaoka Yoshio , Mochizuki Yohichi
Published: September 2002

Small hepatocytes (SHs), which are known to be hepatic progenitor cells, were isolated from an adult rat liver. SHs in a colony sometimes change their shape from small to large and from flat to rising/piled‐up. The aim of the present study is to clarify whether the alteration of cell shape is correlated with the maturation of SHs and whether extracellular matrix (ECM) can induce the morphological changes of SHs. We used liver‐enriched transcription factors (LETFs) such as hepatocyte nuclear factor (HNF) 4α, HNF6, CCAAT/enhancer binding proteins (C/EBP) α, and C/EBPβ, tryptophan 2,3‐dioxygenase (TO), and serine dehydratase (SDH) as markers of hepatic maturation. To enrich the number of SH colonies, the colonies were isolated from dishes and replated. Replated colonies proliferated and the average number of cells per colony was about five times larger at day 9 than at day 1. When the cells were treated with laminin, type IV collagen, a mixture of laminin and type IV collagen, Matrigel™ or collagen gel (CG), only the cells treated with Matrigel dramatically changed their shape within several days and had reduced growth activity, whereas the cells treated with other ECM did not. HNF4α, HNF6, C/EBPα, C/EBPβ, and TO were well expressed in the cells treated with Matrigel. Furthermore, addition of both glucagon and dexamethasone dramatically induced the expression of SDH mRNA and protein in the cells treated with Matrigel. In conclusion, morphological changes of SHs may be correlated with hepatic maturation and basement membrane (BM)‐like structure may induce the morphological changes of SHs. J. Cell. Biochem. 87: 16–28, 2002. © 2002 Wiley‐Liss, Inc.
Cyclic AMP mediated GSTP1 gene activation in tumor cells involves the interaction of activated CREB‐1 with the GSTP1 CRE: A novel mechanism of cellular GSTP1 gene regulation
Authors: Lo Hui‐Wen , Ali‐Osman Francis
Published: September 2002

The human GSTP1 gene is frequently over‐expressed in many human cancers and the expression increases with tumor progression and is associated with a more aggressive biology, poor patient survival, and resistance to therapy. The molecular regulation of the human GSTP1 gene during malignancy is, however, still not well understood. Recently, we reported the presence of a cAMP response element (CRE) in the 5′‐region of the human GSTP1 gene, raising the possibility that the cAMP signaling pathway, frequently aberrant in human cancers, may play an important role in the transcriptional activation of the GSTP1 gene in human tumors. In this study, we report that the GSTP1 gene is an early cAMP response gene. Treatment of cells of the human lung carcinoma cell line, Calu‐6, with 25 μM forskolin to activate the cAMP pathway resulted in a rapid and significant (sevenfold after 30 min) increase in GSTP1 gene transcripts, which peaked at 12‐fold after 4 h. The forskolin‐activated GSTP1 transcription in Calu‐6 cells was suppressed dose‐dependently by a 2‐h pre‐treatment with 0.1, 1.0, and 10 μ of the adenylate cyclase inhibitor, 2′, 5′‐dideoxyadenosine. Western blot analysis showed a rapid, fivefold increase, in GSTP1 protein levels after treatment with 25 μM forskolin, with a peak at 2 h post‐treatment. The levels of phosphorylated CRE (Ser133) binding protein‐1 (CREB‐1) increased rapidly, sevenfold at 30 min, and reached 10‐fold at 4 h following forskolin treatment. Intracellular cAMP levels also increased rapidly reaching 12‐fold at 30 min. Gel mobility shift and supershift assays and DNase I footprinting analyses demonstrated that CREB‐1 bZIP and CREB‐containing nuclear extracts recognized the GSTP1 CRE with high affinity and specificity. Binding of CREB‐1 bZIP to the GSTP1 CRE was abolished when the GSTP1 CRE sequence, 5′‐CGTCA‐3′, was mutated at the core nucleotides. Finally, transfection studies using luciferase plasmid constructs showed the GSTP1 CRE to be required for the cAMP‐activated gene expression. Together, these findings describe a novel cAMP‐ and CREB‐1‐mediated mechanism of transcriptional regulation of the GSTP1 gene and suggest that this may be an important mechanism underlying the increased GSTP1 expression observed in tumors with an aberrant cAMP signaling pathway and in normal cells under conditions of stress, associated with increased intracellular cAMP. J. Cell. Biochem. 87: 103–116, 2002. © 2002 Wiley‐Liss, Inc.
Runx2, A multifunctional transcription factor in skeletal development
Authors: Komori Toshihisa
Published: September 2002

The identification of Runx2 (runt‐related protein 2) function has greatly advanced the understanding of skeletal development over the last 5 years. Runx2 is regulated transcriptionally and post‐translationally through the activity of many identified factors, although, the physiological significance of each remains to be demonstrated. The interaction of Runx2 with other transcription factors and cofactors has been shown to be important in Runx2‐dependent gene regulation. Runx2 plays important roles in multiple steps of skeletal development. Runx2 determines the lineage of osteoblasts from multipotent mesenchymal cells, enhances osteoblast differentiation at an early stage, and inhibits osteoblast differentiation at a late stage. Runx2 plays crucial roles in chondrocyte maturation and in the specification of cartilage phenotypes. Furthermore, Runx2 is involved in vascular invasion into cartilage and osteoclastogenesis. Therefore, the determination of Runx2 function and the investigation of the cascades of Runx2‐dependent gene regulation are important in the elucidation of skeletal biology. J. Cell. Biochem. 87: 1–8, 2002. © 2002 Wiley‐Liss, Inc.
Okadaic acid stimulates osteopontin expression through de novo induction of AP‐1
Authors: Kim Hyun‐Jung , Lee Mi‐Hye , Kim Hyun‐Jung , Shin Hong‐In , Choi Je‐Yong , Ryoo Hyun‐Mo
Published: September 2002

Osteopontin, a major non‐collagenous bone matrix protein, is strikingly upregulated in various tissues under certain pathologic conditions, including cancer. However, the mechanism of upregulation of the osteopontin gene in tumor cells remains unclear. Okadaic acid, a strong non‐phorbol ester tumor promoter, is known to stimulate the expression of osteopontin. The aim of the present study was to understand the mechanism by which okadaic acid regulates osteopontin gene expression. Okadaic acid stimulated osteopontin mRNA expression in several cell lines within 3 h, and the increase in osteopontin mRNA was sustained for 24 h. New protein synthesis was required for the okadaic acid‐elicited increase in osteopontin mRNA expression. A serial promoter deletion study showed that the okadaic acid‐response element is located between positions −265 and −73, a sequence that includes the Runx2, Ets‐1, and AP‐1 binding sequences. Okadaic acid increased the mRNA expression of AP‐1 components but not of Runx2 or Ets‐1. Site‐directed mutagenesis and electrophoretic mobility shift assays confirmed that protein binding of the AP‐1 consensus sequence is necessary for the okadaic acid‐mediated osteopontin gene upregulation. These results indicate that de novo induction of the oncoprotein AP‐1 is required for okadaic acid‐stimulated osteopontin gene upregulation. J. Cell. Biochem. 87: 93–102, 2002. © 2002 Wiley‐Liss, Inc.
The development and validation of the Dormitory Observation Report: A behavioral rating instrument for juvenile delinquents in residential care
Authors: Veneziano Louis , Veneziano Carol
Published: September 2002

In order to provide an objective measure of problematic behavioral patterns among juvenile delinquents in residential facilities, the Dormitory Observation Report (DOR) was developed. The DOR assesses 11 dimensions of problematic behavioral patterns (e.g., physical assaultiveness, manipulativeness), as well as three dimensions of desirable behavioral patterns expected in an institutional setting (e.g., independent functioning, personal hygiene, care of surroundings). Empirical study regarding the reliability and validity of the DOR are reported, and the results are discussed in terms of the theoretical and practical implications of this instrument. © 2002 Wiley Periodicals, Inc. J Clin Psychol 58: 1103–1117, 2002.
The reliability of the Massachusetts Substance Abuse Management Information System
Authors: Soldz Stephen , Panas Lee , Rodriguez‐Howard Mayra
Published: September 2002

State substance abuse management information systems increasingly are becoming important tools for research, program management, and policy formulation at federal and state levels. These systems are currently undergoing radical expansion, leading to the creation of statewide performance and outcome monitoring systems for publicly‐funded substance abuse treatment. This expansion makes imperative increased knowledge of the psychometric properties of the data in these systems. This study develops a method for examining the reliability of such data and applies it to the Massachusetts Substance Abuse Management Information System (SAMIS). Cohen's κ, intraclass correlations, and the techniques of Heise (1969) are used to assess the reliability of different types of variables. Results show that key variables on the SAMIS Admission Form exhibit moderate to high reliability, supporting the use of this data for aggregate analyses. At the same time, caution should be used in making judgments about individual patients. © 2002 Wiley Periodicals, Inc. J Clin Psychol 58: 1057–1069, 2002.