In-vitro cytocompatibility of dental resin monomers on osteoblast-like cells

OBJECTIVES

Dental resin-based materials are widely used in modern dentistry. Especially, resin cements enjoy great popularity and are utilized in many applications. Nevertheless, monomers could be released from the resinous matrix, thus interact with surrounding tissues, cause adverse biological reactions and may lead in cases of implant retained restorations to peri-implant bone destruction. Hence, we performed an in-vitro study to determine cytotoxicity of resin monomers on osteoblast-like cells.

METHODS

Three permanent osteoblast-like cell lines from tumor origin (MG-63 and Saos-2) as well as immortalized human fetal osteoblasts (hFOB 1.19) were used and treated with different concentrations of the main monomers: BisGMA, UDMA, TEGDMA and HEMA. The impact on cell viability was monitored using three different cytotoxicity tests: alamarBlue, XTT, and LDH assay. Mean±SEM were calculated and statistical analysis was performed with GraphPad Prism software.

RESULTS

All monomers tested caused concentration dependent cytotoxic effects on the three investigated osteoblast-like cell lines. Although all three cell viability assays showed comparable results in cytotoxic ranking of the monomers (BisGMA > UDMA > TEGDMA > HEMA), higher differences in the absolute values were detected by the various test methods In addition, also a cell line dependent influence on cell viability could be identified with higher impact on the immortalized hFOB 1.19 cells compared to both osteosarcoma cell lines (MG-63, Saos-2).

CONCLUSIONS

Monomer concentrations detected in elution studies caused toxic effects in osteoblast-like cells. Although the results from in-vitro studies cannot be directly transferred to a clinical situation our results indicate that released monomers from composite resin cements may cause adverse biological effects and thereby possibly lead to conditions favoring peri-implantitis and bone destruction.

CLINICAL SIGNIFICANCE

The wide use of composite resin cements especially in implant-prosthetic treatments should be scrutinized to avoid possible clinical implications between eluted resin monomers and bone cells leading to conditions favoring peri-implantitis and bone destruction.

Ethnicity predicts viral rebound after travel to the tropics in HIV-infected travelers to the tropics in the Swiss HIV Cohort Study

OBJECTIVES

The number of HIV-infected individuals from developed countries travelling to tropical and subtropical areas has increased as a result of the clinical and survival benefits of combination antiretroviral therapy. The aim of our study was to describe the traveler population in the SHCS and to determine the frequency of viral rebound in virologically suppressed individuals after a travel episode to the tropics compared to non-travelers.

METHODS

Swiss HIV Cohort Study participants with at least one follow-up visit between 1 January 1989 and 28 February 2015 were eligible for inclusion in the study. The primary outcome was the occurrence of viral rebound (viral load > 200 HIV-1 RNA copies/mL) after a travel episode compared with a nontravel episode in previously suppressed individuals (≤ 200 copies/mL). All virologically suppressed patients contributed multiple travel or nontravel episodes to the analysis. Logistic regression was performed including factors associated with viral rebound.

RESULTS

We included 16 635 patients in the study, of whom 6084 (36.5%) had ever travelled to the tropics. Travel frequency increased over time, with travellers showing better HIV parameters than nontravellers [less advanced Centers for Disease Control and Prevention (CDC) stage and higher CD4 count nadir]. Viral rebound was seen in 477 (3.9%) of 12 265 travel episodes and in 5121 (4.5%) of 114 884 nontravel episodes [unadjusted odds ratio (OR) 0.87; 95% confidence interval (CI) 0.78-0.97]. Among these 477 post-travel viral rebounds, 115 had a resistance test performed and 51 (44%) of these showed new resistance mutations. Compared with European and North American patients, the odds for viral rebound were significantly lower in Southeast Asian (OR 0.67; 95% CI 0.51-0.88) and higher in sub-Saharan African (SSA) patients (OR 1.41; 95% CI 1.22-1.62). Travel further increased the odds of viral rebound in SSA patients (OR 2.00; 95% CI 1.53-2.61).

CONCLUSIONS

Region of origin is the main risk factor for viral rebound rather than travel per se. Pre-travel adherence counselling should focus on patients of SSA origin.

[Not Available]

Angesichts der demografischen Entwicklung ist mit einem Anstieg pflegebedürftiger, immobiler Patienten mit totaler Zahnlosigkeit zu rechnen, sodass zukünftig zeit- und kosteneffiziente Versorgungsmöglichkeiten von grossem Interesse sind. Hierbei könnten CAD/CAM-Technologien interessante Alternativen zum konventionellen Herstellungsprozess darstellen. Im Rahmen eines Fallberichtes wurde das Baltic Denture System der Firma Merz Dental ausgetestet und eine Patientin im herkömmlichen sowie im digitalen Workflow mit neuen Prothesen versorgt. Nach Funktionsabformung und Registrierung mit vorgegebenen Registrierbehelfen im Sinne von vereinfachten Prothesenkörpern wurden die gewonnenen Daten im zahntechnischen Labor digitalisiert und die Prothesen durch einen Fräsvorgang aus vorgefertigten Rohlingen, bei denen schon die Prothesenzähne im Prothesenkörper integriert sind, umgesetzt. Trotz gewissen Herausforderungen bei der Kombination aus Abformung und Bissnahme konnte die Patientin sehr zufriedenstellend mit den neuen digitalen Prothesen versorgt werden.

Collective cell migration of thyroid carcinoma cells: a beneficial ability to override unfavourable substrates

PURPOSE

Tumor cell invasion and metastasis are life threatening events. Invasive tumor cells tend to migrate as collective sheets. In the present in vitro study we aimed to (i) assess whether collective tumor cells gain benefits in their migratory potential compared to single cells and (ii) to identify its putative underlying molecular mechanisms.

METHODS

The migratory potential of single and collective carcinoma cells was assessed using video time lapse microscopy and cell migration assays in the absence and presence of seven potential gap junction inhibitors or the Rac1 inhibitor Z62954982. The perturbation of gap junctions was assessed using a dye diffusion assay. In addition, LDH-based cytotoxicity and RT-PCR-based expression analyses were performed.

RESULTS

Whereas single breast, cervix and thyroid carcinoma cells were virtually immobile on unfavourable plastic surfaces, we found that they gained pronounced migratory capacities as collectives under comparable conditions. Thyroid carcinoma cells, that were studied in more detail, were found to express specific subsets of connexins and to form active gap junctions as revealed by dye diffusion analysis. Although all potential gap junction blockers suppressed intercellular dye diffusion in at least one of the cell lines tested, only two of them were found to inhibit collective cell migration and none of them to inhibit single cell migration. In the presence of the Rac1 inhibitor Z62954982 collective migration, but not single cell migration, was found to be reduced up to 20 %.

CONCLUSIONS

Our data indicate that collective migration enables tumor cells to cross otherwise unfavourable substrate areas. This capacity seems to be independent of intercellular communication via gap junctions, whereas Rac1-dependent intracellular signalling seems to be essential.

X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser

X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH₂ targets on the OMEGA laser facility at the Laboratory for Laser Energetics in Rochester, NY. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Knowledge gained in this experiment shows a promising future for further XRTS measurements on indirectly driven OMEGA targets.

Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS

Atomic clusters can serve as ideal model systems for exploring ultrafast (∼100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination with a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.

Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility

We are developing x-ray Thomson scattering for applications in implosion experiments at the National Ignition Facility. In particular we have designed and fielded MACS, a high-efficiency, gated x-ray spectrometer at 7.5-10 keV [T. Döppner et al., Rev. Sci. Instrum. 85, 11D617 (2014)]. Here we report on two new Bragg crystals based on Highly Oriented Pyrolytic Graphite (HOPG), a flat crystal and a dual-section cylindrically curved crystal. We have performed in situ calibration measurements using a brass foil target, and we used the flat HOPG crystal to measure Mo K-shell emission at 18 keV in 2nd order diffraction. Such high photon energy line emission will be required to penetrate and probe ultra-high-density plasmas or plasmas of mid-Z elements.

High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen and focused on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].

Oral pathogens change proliferation properties of oral tumor cells by affecting gene expression of human defensins

The impact of oral pathogens onto the generation and variability of oral tumors has only recently been investigated. To get further insights, oral cancer cells were treated with pathogens and additionally, as a result of this bacterial cellular infection, with human defensins, which are as anti-microbial peptide members of the innate immune system. After cell stimulation, proliferation behavior, expression analysis of oncogenic relevant defensin genes, and effects on EGFR signaling were investigated. The expression of oncogenic relevant anti-microbial peptides was analyzed with real-time PCR and immunohistochemistry. Cell culture experiments were performed to examine cellular impacts caused by stimulation, i.e., altered gene expression, proliferation rate, and EGF receptor-dependent signaling. Incubation of oral tumor cells with an oral pathogen (Porphyromonas gingivalis) and human α-defensins led to an increase in cell proliferation. In contrast, another oral bacterium used, Aggregatibacter actinomycetemcomitans, enhanced cell death. The bacteria and anti-microbial peptides exhibited diverse effects on the transcript levels of oncogenic relevant defensin genes and epidermal growth factor receptor signaling. These two oral pathogens exhibited opposite primary effects on the proliferation behavior of oral tumor cells. Nevertheless, both microbe species led to similar secondary impacts on the proliferation rate by modifying expression levels of oncogenic relevant α-defensin genes. In this respect, oral pathogens exerted multiplying effects on tumor cell proliferation. Additionally, human defensins were shown to differently influence epidermal growth factor receptor signaling, supporting the hypothesis that these anti-microbial peptides serve as ligands of EGFR, thus modifying the proliferation behavior of oral tumor cells.

X-ray scattering measurements on imploding CH spheres at the National Ignition Facility

We have performed spectrally resolved x-ray scattering measurements on highly compressed polystyrene at pressures of several tens of TPa (100 Mbar) created by spherically convergent shocks at the National Ignition Facility. Scattering data of line radiation at 9.0 keV were recorded from the dense plasma shortly after shock coalescence. Accounting for spatial gradients, opacity effects, and source broadening, we demonstrate the sensitivity of the elastic scattering component to carbon K-shell ionization while at the same time constraining the temperature of the dense plasma. For six times compressed polystyrene, we find an average temperature of 86 eV and carbon ionization state of 4.9, indicating that widely used ionization models need revision in order to be suitable for the extreme states of matter tested in our experiment.

In vitro biocompatibility of ICON(®) and TEGDMA on human dental pulp stem cells

OBJECTIVES

Resin infiltrants have been successfully used in dental medicine preventing the progression of tooth decay in an early phase of caries development. ICON(®) is an infiltrant of low-viscosity which penetrates via dentinal tubules into the lesion in dependence of the demineralization depth. Hence, we performed an in vitro study to determine the effect of ICON(®) on human dental pulp stem cells (hDPSCs).

METHODS

Using explant technique, primary hDPSCs were collected from extracted teeth. Characterization and isolation were performed with typical mesenchymal stem cell markers (Stro-1, CD73, CD90, CD105) and hDPSCs differentiation was validated by immunofluorescence and flow cytometry. HDPSCs were stimulated with light-cured ICON(®) (lc) and non-light-cured ICON(®) (nc) conditioned media as well as different TEGDMA concentrations followed by the analysis of cytotoxicity, pro- and anti-inflammatory responses and differentiation using XTT assay, RT-PCR and ELISAs, respectively.

RESULTS

Initial analysis demonstrated that hDPSCs express characteristic mesenchymal stem cell markers and differentiate into adipocytes, chondrocytes and osteoblasts. Notably, ICON(®) nc dramatically reduced cell viability (up to 98.9% after 48h), whereas ICON(®) lc showed only a modest cytotoxicity (10%). Data were in line with cytokine expression demonstrating increased levels of IL-6 and IL-8 as well as decreased IL-10 after ICON(®) nc exposure compared to ICON(®) lc. ICON(®) lc caused almost no alterations of DSPP, whereas ICON(®) nc markedly elevated DSPP mRNA levels (130.3-times). A concentration-dependent effect was observed in TEGDMA challenged hDPSCs.

SIGNIFICANCE

ICON(®) is a successful minimal invasive technique. However, clinicians should strictly follow manufacturer's instructions to prevent adverse effects.

Cellular Distribution and Gene Expression Pattern of Metastasin (S100A4), Calgranulin A (S100A8), and Calgranulin B (S100A9) in Oral Lesions as Markers for Molecular Pathology

The objective of this study was to analyze cellular localization and expression levels of oncologic relevant members of the S100 family in common oral lesions.Biopsies of various oral lesions were analyzed. S100A4 showed a higher expression rate in leukoplakias and oral squamous cell carcinomas. Transcript levels of S100A8 and S100A9 were significantly decreased in malignant OSCCs. A correlation could be drawn between the expression levels of these genes and the pathological characteristics of the investigated lesions. S100A4, A8, and A9 proteins represent promising marker genes to evaluate the risk potential of suspicious oral lesions in molecular pathology.

Expression Pattern of Matrix Metalloproteinase 20 (MMP20) in Human Tumors

BACKGROUND/AIM

Matrix metalloproteinase 20 (MMP20) is a member of the family of matrix metalloproteinases. Under normal conditions the expression of MMP20 is restricted to ameloblasts and odontoblasts. In order to identify a possible expression of MMP20 under pathological conditions, we investigated three major human tumor entities, i.e. colon, breast and lung tumors, on the mRNA and protein level.

MATERIALS AND METHODS

Real-time RT-PCR and immunocytochemical analyses of established human tumor cell lines were employed for our study; immunohistochemical analysis was performed on both primary tumors and normal control tissues.

RESULTS

MMP20 was identified on both the mRNA and the protein level in breast MCF-7, colon HT-29, and lung A549 cell lines. MMP20 was also detected in primary tumor tissue by immunohistochemistry.

CONCLUSION

MMP20 is a new potential candidate for tumor diagnosis or therapy.