Evaluation of monomer leaching from a dual cured resin cement.

Purpose: An increasing number of inlay cavities is restored with tooth-colored materials, especially ceramics are cemented with resin cements. The comonomer TEGDMA and other monomers Bis-GMA and UDMA have been identified as the main compounds released from polymerized resin cements into aqueous media. The present investigation was conducted to clarify the leaching behavior of the monomers of dual polymerized resin cement. Material and methods: Ten freshly extracted caries and restoration free molar teeth were used in this study. Standardized Class I preparations were prepared in all teeth. Lithium disilicate based (IPS Empress Esthetic) ceramic inlays were cemented with dual polymerized resin cement (Variolink II). After cementation, specimens were stored in 75% ethanol solution. High-performance liquid chromatography (HPLC) was used to analyze the amounts of three monomers in the solution (after 10 min, 1 h, 24 h, 3, 7, 14, and 21 days). Two-way ANOVA and Tukey HSD tests were used to evaluate the results (p < 0.05). Results: There were statistically significant differences among the amounts of the monomers (p < 0.01) and also among time periods (p < 0.01). While the TEGDMA resulted in significantly higher amount than Bis-GMA and UDMA, there were no statistically significant differences between amounts of Bis-GMA, UDMA (p = 0.06). The cumulative amount of monomers was the highest after 21 days (p < 0.01). Conclusion: In the case of resin cement, leaching of TEGDMA was the highest and the cumulative amount of leaching monomers from resin cement was influenced by the time. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008.

Altintas SH, Usumez A.

Department of Prosthodontics, Karadeniz Technical University, Trabzon, Turkey.

Wear particle analysis of highly crosslinked polyethylene isolated from a failed total hip arthroplasty.

Polyethylene wear particles are one of the most important factors affecting the results of total hip arthroplasty (THA). To reduce wear generation and to achieve better long-term results of THA, highly crosslinked polyethylene (HXPE) has recently been introduced and come into wide use. Thus far, however, there have been no reports on in vivo analysis of HXPE wear particles. We isolated HXPE wear particles from periprosthetic tissue of a failed THA and analyzed using scanning electron microscope. The number of particles was 5.33 x 10(7) g(-1). Particle size (equivalent circle diameter) was 0.66 +/- 0.40 mum (mean +/- standard error). Aspect ratio and roundness were 1.37 +/- 0.26 and 1.44 +/- 0.67, respectively. All the particles were round shaped, and \”fibrils\” or \”shreds\” were not detected. Thus far, this was the first report on in vivo wear particle analysis of HXPE. HXPE generated less, smaller, and rounder particles, compared with the corresponding reported values for particles generated from conventional polyethylene. These characteristics might affect macrophage response, osteolysis, and long-term results of THA with HXPE. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008.

Minoda Y, Kobayashi A, Sakawa A, Aihara M, Tada K, Sugama R, Iwakiri K, Ohashi H, Takaoka K.

Department of Orthopaedic Surgery, Kansai Rosai Hospital, 3‐1‐69 Inabasou, Amagasaki, Hyogo 660‐8511, Japan.

Swelling characteristics and drug delivery properties of nifedipine-loaded pH sensitive alginate-chitosan hydrogel beads.

The aim of the present work was to investigate the swelling behavior and in vitro release of nifedipine from alginate-chitosan hydrogel beads. Structure and surface morphology of the hydrogel were characterized by FTIR and SEM, respectively. Alginate-chitosan mixed beads and alginate-chitosan coated beads were prepared by ionic gelation method. The swelling ability of the beads and in vitro release of nifedipine in simulated gastric fluid (pH 1.5) and different phosphate buffer solutions (pH 2.5, 5.0, 6.8, 7.4, and 8.0) were found to be dependent on the presence of the polyelectrolyte complex between chitosan and alginate. The amount of nifedipine released from the mixed beads at pH 1.5 was relatively low (42%), whereas this value approached to 99% at pH 6.8. In comparison with the mixed beads, the released nifedipine from the coated beads was minimal at pH 1.5 (18%), whereas approximately 99% nifedipine was released at pH 6.8. The results suggested that the coated beads can hold drug better at low pH than the mixed beads and show excellent pH sensitivity. Therefore, the alginate-chitosan coated beads could be a suitable polymeric carrier for drug delivery in the intestinal tract. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008.

Dai YN, Li P, Zhang JP, Wang AQ, Wei Q.

The Second Hospital of Lanzhou University, Lanzhou 730030, China.

Contact-free determination of material characteristics using a newly developed pressure-operated strain-applying bioreactor.

Experimental mechanostimulation of biologic samples serves to understand fundamental processes in mechanobiology. Unfortunately, present techniques do not allow contact-free investigation of material characteristics. We developed a mechanostimulator that functions under the assumption that the counterforce generated by a biologic sample placed on a carrier membrane (test-on-carrier) is extractable from the total signal. As material characteristics of biologic samples are poorly defined, we substituted them by polyurethane and latex membranes. Based on the knowledge of the previously measured carrier membrane\’s compliance, we calculated the test membrane\’s compliance from the pressure-volume relationship inside the bioreactor. We hypothesized that knowing the carrier membranes\’ compliance allows calculation of the sample\’s compliance. Compliances of latex membranes were larger than those of polyurethane ones (p < 0.05). The average differences between calculated and directly determined compliances were 3.9% +/- 2.7% and 6.7% +/- 4.8% (mean +/- SD) under static and dynamic mechanostimulation, respectively (p > 0.05). The variability of compliance values was several fold larger (p < 0.01) for latex-on-polyurethane compared to polyurethane-on-latex combinations. There was high correlation between Young\’s modulus as determined from static compliance estimation and by uniaxial stretching in a tension-testing machine (r(2) = 0.987, p < 0.001). In conclusion, our mechanostimulator allowed reliable contact-free determination of material characteristics and may thus be suitable for contact-free assessment of biologic samples. The compliance of the carrier membrane should be at least two times larger than the compliance of the tested material. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008.

Schumann S, Stahl CA, Möller K, Schneider M, Metzke R, Wall WA, Priebe HJ, Guttmann J.

Section for Experimental Anaesthesiology, University Hospital of Freiburg, Freiburg, Germany.

Chromosome 8q24 markers: Risk of early-onset and familial prostate cancer.

Recent admixture mapping and linkage/association studies have implicated an approximately 1 Mb region on chromosome 8q24 in prostate cancer susceptibility. In a subsequent follow-up investigation, Haiman et al. (Nat Genet 2007;39:638-44) observed significant, independent associations between 7 markers within this region and sporadic prostate cancer risk in a multi-ethnic sample. To clarify the risk associated with hereditary prostate cancer, we tested for prostate cancer association with 6 of these 7 markers in a sample of 1,015 non-Hispanic white men with and without prostate cancer from 403 familial and early-onset prostate cancer families. Single nucleotide polymorphisms (SNPs) rs6983561 and rs6983267 showed the strongest evidence of prostate cancer association. Using a family-based association test, the minor (\”C\”) allele of rs6983561 and the major (\”G\”) allele of rs6983267 were preferentially transmitted to affected men (p < 0.05), with estimated odds ratios (ORs) of 2.26 (95% confidence interval of 1.06-4.83) and 1.30 (95% confidence interval of 0.99-1.71), respectively, for an additive model. Notably, rs6983561 was significantly associated with prostate cancer among men diagnosed at an early (<50 years) but not later age (p = 0.03 versus p = 0.21). Similarly, the association with rs6983267 was (not) statistically significant among men with(out) clinically aggressive disease (p = 0.007 versus p = 0.34). Our results confirm the association of prostate cancer with several of the SNPs on chromosome 8q24 initially reported by Haiman et al. In addition, our results suggest that the increased risk associated with these SNPs is approximately doubled in individuals predisposed to develop early onset or clinically aggressive disease. (c) 2008 Wiley-Liss, Inc.

Beebe-Dimmer JL, Levin AM, Ray AM, Zuhlke KA, Machiela MJ, Halstead-Nussloch BA, Johnson GR, Cooney KA, Douglas JA.

Karmanos Cancer Institute and Wayne State University, Detroit, MI.

Arming parvoviruses with CpG motifs to improve their oncosuppressive capacity.

Oncolytic viruses represent novel tools for cancer treatment. Besides specifically killing cancer cells (oncolysis), these agents also provide danger signals, prompting the immune system to eliminate virus-infected tumours. As a consequence of oncolytic events, the innate and adaptive immune systems gain access to tumour antigens, which result in cross-priming and vaccination effects. Here the aim was to see whether we could enhance this adjuvant capacity by incorporating immunostimulatory CpG motifs into the single-stranded genome of an oncolytic parvovirus (H-1PV). We engineered 2 CpG-enriched H-1PV variants (JabCG1 and JabCG2), preserving both the replication competence and the oncolytic features of the parental virus. In keeping with their increased CpG content, the JabCG1 and JabCG2 genomes proved in vitro to be more potent triggers of TLR-9-mediated signalling than wild-type H-1PV DNA. Antitumour activity was evaluated in a rat model of MH3924A hepatoma lung metastases, where an infection with parental or modified viruses served as an ex vivo adjuvant to a subcutaneously administered autologous cell vaccine. In this setup, which excludes direct oncolytic effects on metastases, the JabCG2 vector displayed enhanced immunogenicity, inducing markers of cellular immunity (IFNgamma) and dendritic cell activation (CD80, CD86) in mediastinal (tumour-draining) lymph nodes. This led to a significantly reduced metastatic rate (50%) as compared to other vaccination schedules (H-1PV-, JabCG1-, JabGC- or mock-treated cells). The data provide proof of principle that increasing the number of immunostimulatory CpG motifs within oncolytic viruses makes it possible to improve their overall anticancer effect by inducing antitumour vaccination. (c) 2008 Wiley-Liss, Inc.

Raykov Z, Grekova S, Leuchs B, Aprahamian M, Rommelaere J.

Infection and Cancer Program, Abteilung F010 and Inserm U701, Deutsches Krebsforschungszentrum, Heidelberg, Germany.

Rebound increase in migraines following PFO closure.

Bhindi R, Ormerod OJ.

Cardiology Department, John Radcliffe Hospital, Oxford, Oxfordshire, United Kingdom.

Rebuttal: Patent foramen ovale and unexplained ischemic cerebrovascular events in children.

Benedik MP, Zaletel M, Meglič NP, Podnar T.

Department of Pediatrics, University Medical Center, Ljubljana, Slovenia.

Relationship between patent foramen ovale and ischemic cerebrovascular events in children.

Sharma VK, Teoh HL, Chan BP.

Division of Neurology, Department of Medicine, National University Hospital, Singapore.

PFO closure in children.

Kenny D, Turner M, Martin R.

Bristol Congenital Heart Centre, Bristol Royal Hospital for Children and Bristol Royal Infirmary, Bristol BS28BJ, United Kingdom.