Laser-induced novel patterns: As smart strain actuators for new-age dental implant surfaces

WOS: 000311217500092Surface morphologies of titanium implants are of crucial importance for long-term mechanical adaptation for following implantation. One major problem is the stress shielding effect which originates from the mismatch of the bone and the implant elasticity. It is time for a paradigm shift and for an exploration of novel smart surfaces to prevent this problem. Several surface treatment methods have traditionally been used to modify the surface morphology of titanium dental implants. The laser micro-machining can be considered as a unique and promising, non-contact, no media, contamination free, and flexible treatment method for modifying surface properties of materials in the biomedical industry. The aim of the present study is two folds; to develop novel 3D smart surfaces which can be acted as strain actuators by nanosecond laser pulse energies and irradiation strategies. And analyze these smart surface morphologies using finite element methods in order to estimate their internal stiffness values which play a great role on stress shielding effect. Novel 3D smart strain actuators were prepared using an ytterbium fiber laser (lambda = 1060 nm) with 200-250 ns pulse durations on commercial pure titanium dental implant material specimen surfaces and optimum operation parameters were suggested. (C) 2012 Elsevier B.V. All rights reserved.Ikon Makina; Metrosan Ltd. Sti.-Meteor Medikal A.S.; Lazer Metal Ltd.Sti.The authors would like to thank Ikon Makina, Metrosan Ltd. Sti.-Meteor Medikal A.S., and Lazer Metal Ltd.Sti. for supporting our experimental investigations

The Reliability and Validity of Modified Four-Square-Step-Test and Step-Test in Older Adults

Aims: To demonstrate the reliability and validity of the modified four-square step test (mFSST) and the step test (ST) in community-dwelling older adults. Methods: Fifty older adults were recruited. The test-retest reliability of the mFSST and ST was evaluated with one-hour-interval. The mFSST and ST was compared with Timed up and Go Test (TUG) and Five Times Sit to Stand Test (FTST) to demonstrate concurrent validity. Results: The mean age of the participants was 72.0 +/- 5.7 years. The test-retest reliability of mFSST and ST was excellent (ICC = 0.971 and 0.938, respectively). In concurrent validity analysis, the mFSST was strongly correlated with TUG and FTST (r(1)=0.755, r(2)=0.575, p < 0.001). Both the ST (right) and ST (left) were highly correlated with TUG and FTST (r= -0.527 to -0.578, p < 0.001). In addition, the ST (right) and ST (left) were highly correlated with FTST (r(1)= -0.533, r(2)= -0.527, p < 0.001). Conclusions: mFSST and ST was proven to be valid and reliable in older adults

Pulsed Laser-Induced Micro-Pits: As Bone Stabilizers

6th International WLT Conference on Lasers in Manufacturing (LiM) -- MAY 23-26, 2011 -- Munich, GERMANYWOS: 000298853300033Mechanical interlocking concept is a crucial criteria for osseointegration which is based on micro-porous surface structures. Several surface treatment methods have been used to modify the surface morphology of titanium implants in order to increase the effective interfacial area. The aim of the present preliminary study is two folds: to develop 3D finite element models for micro-pits on implant surfaces as bone stabilizers in order to evaluate the mechanical response of interfacial area and compare the estimated interfacial shear strength and the maximum effective shear strain with other biomechanical theories. Second is to produce novel regular micro-pit patterns using a 20 Watt ytterbium fiber laser and characterize these novel micro-stabilizers.German Sci Laser Soc (WLT

Alteration on global and gene-spesific DNA methylation and global histone modifications in HepG2 cells in response to BPA

Bisphenol A (BPA), as synthetic monomer used in industry in the production of polycarbonate plastic and epoxy resins, has endocrine disruptor properties and high risk on human health. Continuous release of free BPA into food, beverages, and the environment has resulted in a widespread human exposure to this chemical. Recent studies have showed the role of endocrine effects of environmental chemicals on the changes in gene expression may be associated with epigenetic mechanisms such as DNA methylation and histone modifications. The aim of the study was to investigate dose-related effects of BPA (0, 0.1 mu M, 1 and 10 mM for 48 and 96 h) on global and gene-spesific (p16, cyclin D2 and Rassf1 genes) DNA methylation in human hepatocarcinoma (HepG2) cells. We also investigated global histone modifications such as H3K9 trimethylation (H3K9me3), H3K9 acetylation (H3K9ac), H3K27 trimethylation (H3K27me3). The 50% inhibitory concentration (IC50) value of BPA was determined as 134 and 180 mu M in HepG2 cells for 24 h by MTT and neutral red uptake (NRU) tests, respectively. We observed decrease on the global levels of 5-methylcytosine and 5-hydroxymethylcytosine at 1 and 10 mM after 96 h BPA exposure. There is no significant alterations on the promoter-region of methylation and expression of p16, cyclin D2 and Rassf1 genes. Global levels of H3K9me3 decreased after 0.1 and 1 mu M concentration of BPA exposure for 48 h, while increased after 96 h 0.1 and 1 mu M of BPA exposure for. Hovewer, it has not been observed significantly changes for the global levels of H3K27me3 and H3K9ac. In this study we suggest that BPA may disrupt epigenetic events by altering global and gene-spesific DNA methylation and histone modifications in HepG2 cells

Effects of BPA on global DNA methylation and global histone 3 lysine modifications in SH-SY5Y cells: An epigenetic mechanism linking the regulation of chromatin modifiying genes

Bisphenol A (BPA), an estrogenic endocrine disruptor, is widely used in the production of polycarbonate plastic and epoxy resins, resulting in high risk on human health. In present study we aimed to investigate the effects of BPA on global and gene specific DNA methylation, global histone modifications and regulation of chromatin modifiying enzymes in human neuroblastoma cells (SH-SY5Y). Cells were treated with BPA at 0.1, 1 and 10 mu M concentrations for 48 and 96h. IC50 value of BPA was determined as 183 and 129 mu M in SH-SY5Y cells after 24h by MTT and NRU tests, respectively. We observed significant alterations on the 5-mC% levels (1.3 fold) and 5-hmC% levels (1.67 fold) after 10 mu M of BPA for 96h. Significant decrease was identified in H3K9me3 and H3K9ac after 10 mu M of BPA for 96h while decrease was observed in H3K4me3 at 10 mu M of BPA for 48h. Alterations were observed in chromatin modifiying genes including G9a, EZH2, SETD8, SETD1A, HAT1, SIRT1, DNMT1, RIZ1 and Suv39h1 after 96h of BPA exposure. Taken together, this study suggests that BPA might modulate the epigenetic regulators which would be key molecular events in the toxicity of endocrine disrupting chemicals

Protective effect of Amaranthus lividus L. on carbon tetrachloride induced hepatotoxicity in rats

Objective: Amaranthus lividus is consumed as popular vegetable in West Black Sea Region of Turkey. In this study, we aimed to evaluate the protective and antioxidant effects of A. lividus on carbon tetrachloride (CCl 4) induced oxidative stress and acute liver injury in rats

Global and region-specific post-transcriptional and post-translational modifications of bisphenol A in human prostate cancer cells.

Bisphenol A (BPA), as synthetic monomer used in the production of polycarbonate plastic and epoxy resins, has endocrine disruptor properties and high risk on human health. Epigenetic alterations could act an important role in BPA-induced toxicity, but its mechanism has not been fully understood. We investigated the effects of BPA on gene expression of chromatin modifying enzymes, promoter methylation of tumor suppressor genes and histone modifications in human prostate carcinoma cells (PC-3). IC50 value of BPA was determined as 217 and 190 mu M in PC-3 cells by WIT and NRU tests, respectively. We revealed an increase in global levels of 5-methylcytocine and 5-hydroxymethylcytocine at 10 mu M of BPA for 96 h. We observed a significant increase on promoter DNA methylation and decrease on gene expression of p16 gene while no change was observed for Cyclin D2 and Rassf1. Significant changes were observed in global histone modifications (H3K9ac, H3K9me3, H3K27me3, and H4K20me3) in PC-3 cells. According to these results, we investigated wide-range epigenetic modifications using PCR arrays. After 96 h BPA exposure, chromatin modifying enzymes including KDM5B and NSD1 were significantly downregulated. Also, promoter methylation of tumor suppressor genes including BCR, GSTP1, LOX, MGMT, NEUROG1, PDLIM4, PTGS2, PYCARD, TIMP3, TSC2 and ZMYDN10 altered significantly. ChIP results showed that H3K9ac, H3K9me3 and H3K27me3 modifications on p16 gene showed significant increases after 1 and 10 mu M of BPA exposure. In conclusion, epigenetic signatures such as DNA methylation and histone modifications could be proposed as molecular biomarkers of BPA-induced prostate cancer progression. (C) 2019 Elsevier Ltd. All rights reserved