Radiology & Medical Imaging eJournal最新文献

{"title":"Multiphoton Imaging of Melanoma 3D Models with Plasmonic Nanocapsules","authors":"P. Zamora-Perez, Can Xiao, Marcos Sanlés-Sobrido, M. Rovira-Esteva, J. J. Conesa, Vladimir Mulens-Arias, D. Jaque, P. Rivera-Gil","doi":"10.2139/ssrn.3910602","DOIUrl":"https://doi.org/10.2139/ssrn.3910602","url":null,"abstract":"Here, we synthesized plasmonic nanocapsules and studied their induced cellular responses in 3D melanoma models for their perspective use as a photothermal therapeutic agent. The wall of the nanocapsules was composed of polyelectrolytes. The inner part was functionalized with discrete gold nanoislands. The cavity of the nanocapsules contained a fluorescent payload to show their ability for loading a cargo. The nanocapsules exhibited simultaneous two-photon luminescent, fluorescent properties and X-ray contrasting ability. The average fluorescence lifetime (τ) of the nanocapsules measured with FLIM (0.3 ns) was maintained regardless of the intracellular environment, thus proving their abilities for bioimaging of models with a complex architecture, such as 3D spheroids. Their multimodal imaging properties are exploited for the first time to study cellular responses following the exposure of 3D melanoma models to the nanocapsules. Specifically, we studied cellular uptake, toxicity, intracellular fate, generation of reactive oxygen species, and effect on the levels of hypoxia by using multi-photon and confocal laser scanning microscopy. Because of the high X-ray attenuation and atomic number of the gold nanostructure, we could image the nanocapsule-cell interactions without processing the sample. We confirmed maintenance of the nanocapsules' geometry in the intracellular milieu with no impairment of the cellular ultrastructure. Furthermore, we observed the lack of cellular toxicity and no alteration in oxygen or reactive oxygen species levels. These results in 3D melanoma models contribute to the development of these nanocapsules for their exploitation in future applications as agents for imaging-guided photothermal therapy. STATEMENT OF SIGNIFICANCE: The novelty of the work is that our plasmonic nanocapsules are multimodal and are responsive to X-ray and multiphoton and single-photon excitation. This allowed us to study their interaction with 2D and 3D cellular structures and specifically to obtain information on tumor cell parameters such as hypoxia, reactive oxygen species (ROS), and toxicity. These nanocapsules will be further validated as imaging-guided photothermal probes.","PeriodicalId":215950,"journal":{"name":"Radiology & Medical Imaging eJournal","volume":"248 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132983515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Robust Image Encryption Model Using Hyperchaotic System and Deoxyribose Nucleic Acid Sequence","authors":"Swetha. T.N, Dr.G.M.Sreerama Reddy","doi":"10.2139/ssrn.3507380","DOIUrl":"https://doi.org/10.2139/ssrn.3507380","url":null,"abstract":"Recently, DNA sequences and hyperchaotic sequence are jointly used for building secure and efficient image encryption model. However, the state-of-art model are not efficient (robust) against noise and cropping attack. Since, in existing model most digits of each pixel are not altered. For enhancing security for encrypting high dimensional images, this work use both hyperchaotic and DNA sequence. Firstly, pseudorandom sequence is generated using hyperchaotic system. This is done to use hyperchaotic sequence for nearly entire process of the encryption where intensity parameters of a high dimensional image are transformed to a serial binary digit stream. Then, this stream of bits is scrambled using hyperchaotic sequence. DNA complementation and algebraic function are conducted among the DNA and the hyperchaotic sequences to attain efficient and robust image encryption performance. Experimental outcome shows proposed image encryption model attain superior performance than stat-of-art model in terms of robustness against cropping attack and noise.","PeriodicalId":215950,"journal":{"name":"Radiology & Medical Imaging eJournal","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133738267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Certificate of Need Regulation and Hospital Behavior: Evidence from MRIs in North Carolina","authors":"B. Perry","doi":"10.2139/ssrn.3225741","DOIUrl":"https://doi.org/10.2139/ssrn.3225741","url":null,"abstract":"Certificate of Need (CON) regulations — restrictions on capital investment — are a key feature of the regulatory environment facing the US hospital industry, yet there is remarkably little evidence on how these regulations affect hospital investment and patient care in practice. In this paper, I use newly collected data on the magnetic resonance imaging (MRI) market in North Carolina and patient-level Medicare claims data to estimate the dynamic effects of marginal relaxations of CON restrictions on provider investment and patient care. Using a regression discontinuity approach that takes advantage of regulatory approval thresholds, I document two sets of key findings. First, CON regulations are a binding constraint on hospital investment. In response to this constraint, there is an active market for unregulated mobile MRI scanners that enable health care providers to mitigate the impact of CON restrictions. Second, CON rules affect not only hospital investment but also restricts utilization of MRI scans. In a specific case, CON regulations reduce the number of scans patients with low back pain receive, reducing medical spending by roughly $400. There is no evidence that this decrease in the intensity of care comes at the cost of increased future low back pain.","PeriodicalId":215950,"journal":{"name":"Radiology & Medical Imaging eJournal","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116987939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Energy X-Ray Diffraction Study of Multiwalled Carbon Nanotubes Fabricated by Arc Discharge Plasma Process","authors":"B. Bagautdinov, K. Ohara, A. A. Babaev","doi":"10.2139/ssrn.3949244","DOIUrl":"https://doi.org/10.2139/ssrn.3949244","url":null,"abstract":"Structural features of multiwalled carbon nanotubes (MWCNTs) have been analyzed quantitatively by high-energy X-ray diffraction (HE-XRD) with atomic pair distribution function (PDF) technique. It has been found that the nanotubes are mainly of scroll type and own an atomic arrangement defined on the nanometer length scale in terms of a unit cell and symmetry. They exhibit multipart local (sub-nanometer) and intermediate range (on nano-length-scale) structures. Thestructural information at different length-scales was used to probe the interlayer spacing distribution within the nanotubes. The radial dependence of interlayer spacing observed in pristine nanotubes present tendency for alteration to uniform spacing of layer in the course of heating-cooling cycle in the range of 298–450 K. These spatial changes illustrate modification of Fermat type stroll with uneven interlayer distances in pristine nanotubes to more stable equidistant interlayer Archimedean spiral type in the heating-cooling treated ones.","PeriodicalId":215950,"journal":{"name":"Radiology & Medical Imaging eJournal","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124407886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}