3D printing of PEEK-based medical devices

open access articlePolyether-ether-ketone (PEEK) is an excellent thermoplastic alternative to metallic biomaterials which is used for loadbearing applications due to its high strength and stiffness, and biocompatibility with no cytotoxic effects. However, a potential clinical concern is that PEEK alone is not bioactive enough, and thus has limited fixation to bone. To overcome this problem, bioactive materials and/or porosity are incorporated into PEEK medical devices. The latest developments in these two strategies are presented. in this paper. Bioactive PEEK/hydroxyapatite (HA) prepared by integration of 3D printing and compression molding is presented in this paper. In addition, nozzle and build plate temperatures for 3D printing of porous PEEK were optimized using genetic algorithm (GA) to achieve the highest mechanical strength for load bearing applications such as spinal fusion cages

ERCC1 and XRCC1 as biomarkers for lung and head and neck cancer

Advanced stage non-small cell lung cancer and head and neck squamous cell carcinoma are both treated with DNA damaging agents including platinum-based compounds and radiation therapy. However, at least one quarter of all tumors are resistant or refractory to these genotoxic agents. Yet the agents are extremely toxic, leading to undesirable side effects with potentially no benefit. Alternative therapies exist, but currently there are no tools to predict whether the first-line genotoxic agents will work in any given patient. To maximize therapeutic success and limit unnecessary toxicity, emerging clinical trials aim to inform personalized treatments tailored to the biology of individual tumors. Worldwide, significant resources have been invested in identifying biomarkers for guiding the treatment of lung and head and neck cancer. DNA repair proteins of the nucleotide excision repair pathway (ERCC1) and of the base excision repair pathway (XRCC1), which are instrumental in clearing DNA damage caused by platinum drugs and radiation, have been extensively studied as potential biomarkers of clinical outcomes in lung and head and neck cancers. The results are complex and contradictory. Here we summarize the current status of single nucleotide polymorphisms, mRNA, and protein expression of ERCC1 and XRCC1 in relation to cancer risk and patient outcomes. © 2011 Vaezi et al, publisher and licensee Dove Medical Press Ltd

The validity of a scoring system in predicting intravenous immunoglobulin treatment failure in children with kawasaki disease

Background: Between 10 and 20 of children with Kawasaki disease (KD) will not respond to intravenous immunoglobulin (IVIG) treatment, and are prone to coronary abnormalities. A variety of predicting scoring systems, including the Kobayashi system, have been proposed, but have not yet been evaluated using Iranian patients. Objectives: To evaluate the Kobayashi scoring system with regard to predicting response to IVIG treatment in Iranian children. Patients and Methods: All patients who received a final diagnosis of KD at Aliasghar children�s hospital between 1982 and 2013, and who met the inclusion criteria, were enrolled in this retrospective cohort study. We excluded patients with missing data, abnormal echocardiographic finding on admission, late admission, atypical or afebrile cases, and those who had received an insufficient amount of IVIG. We compared demographic and echocardiographic data before IVIG, and within 7 days of treatment, as well as C reactive protein (CRP), sodium, aspartate aminotransferase, platelet levels, neutrophil percentage, age of patients, and duration of fever before IVIG administration, in treatment responders and non-responders. Results: Of the 141 cases, 97 patients met the criteria and were enrolled. Of these, 19 (19.6) did not respond to IVIG. A total of 61.8 of patients were male, and the mean patient age was 36.9 months (SD = 32.1 months). Echocardiographic evaluation revealed early coronary involvement in 15.3 of patients, and coronary abnormalities were diagnosed in 10 of patients within the first 10 days of presentation and concurrent with their IVIG treatment. A between-groups comparison of quantitative CRP, absolute neutrophil count, and platelet count showed that platelet count alone was significantly higher in nonresponders (P = 0.04). With regard to items of Kobayashi scoring system, data were present for just 41 cases, but a significant difference between the two groups was shown, with the treatment-refractory group having a significantly higher score (P = 0.002). Receiver-operating characteristic curve analysis revealed that the optimum cut-off point for our population would be 2, which makes the sensitivity of the test equal to 75, with a specificity of 60. Conclusions: This preliminary study showed that patients with KD and a high Kobayashi score are at greater risk of being unresponsive to IVIG treatment. Further studies, preferably multicenter evaluations, are required in order to understand the exact application of various scoring systems in the management of people with KD in Iran. © 2016, Pediartric Infections Research Center

Characterization and Formation Mechanism of Solid Solution in Nanocrystalline Al-5wt%Si Powders Produced by Mechanical Alloying

Due to advantages of mechanical alloying in comparison with liquid state processes, this process has used a lot to synthesis nanostructured alloy. In the present study, aluminum and silicon elemental powders with composition Al-5wt % Si were synthesized by mechanical alloying in high energy planetary ball. X-ray diffractometer and scanning electron microscopic were used to study microstructural and morphological changes of powder particles and formation of solid solution of Al-Si during milling. Crystallite size, lattice strain and lattice parameter were determined by Scherer, Williamson–Hall and Nilson–Reley methods. Minimum crystallite size was 17.895 nm according to Scherer method and 32.644 nm according to Williamson-Hall. Solid solution of Al-Si was formed between 5 h and 30 h, due to crystallite size in nano scale and diffusion process in mechanical alloying. In addition lattice parameter changes and XRD results prove it. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3503

Topological electric current from time-dependent elastic deformations in graphene

We show the possibility of inducing an edge charge current by applying time-dependent strain in gapped graphene samples preserving time reversal symmetry. We demonstrate that this edge current has the same origin as the valley Hall response known to exist in the system.Comment: 5 pages, 3 figures, Accepted for publication in Phys. Rev.

Optical coherence tomography angiography of foveal hypoplasia

AIMS: To discuss foveal development in the context of detailed retinal vasculature imaging in foveal hypoplasia using optical coherence tomography angiography. METHODS: In this case series, the optical coherence tomography angiography results of four patients with idiopathic foveal hypoplasia and two patients with foveal hypoplasia secondary to oculocutaneous albinism are presented. RESULTS: Cases with intact visual acuity demonstrated lower grades of foveal hypoplasia on optical coherence tomography, while those with poor vision demonstrated high grades of foveal hypoplasia. The superficial retinal capillary plexus was intact in the foveal area in all cases, with no demonstrable foveal avascular zone. The deep retinal capillary plexus was absent to variable degrees in most cases, but was most persistent in those cases with reduced vision. CONCLUSIONS: The superficial retinal capillary plexus is present in cases with foveal hypoplasia, while the deep retinal capillary plexus is absent to varying degrees. Our findings support the hypothesis that an intact foveal avascular zone of the deep capillary plexus allows for outer retinal photoreceptor specialisation to occur unimpeded, resulting in preserved visual acuity, while this process may be inhibited by an absent deep capillary foveal avascular zone with resultant poor vision