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- Kifle, Yonatan Habteslassie, et al.
(författare)
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NFC Powered Implantable Temperature Sensor
- 2019
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Ingår i: 2019 41ST ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC). - : IEEE. - 9781538613115 - 9781538613122 ; , s. 4359-4362
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Konferensbidrag (refereegranskat)abstract
- Inductively powered 99% accurate implantable temperature sensor is designed, characterized and the findings are presented in this paper. The implantable sensors deliver a continuous temperature reading to external storage or readout devices via Near Field Communication interface. A 2.76 mu H rectangular inductive coil printed on a thin biocompatible plastic substrate is designed to establish the coupling link through NFC interface with external readout devices. A commercially available wide range temperature sensor chip is mounted along with the developed inductive coil on the same plastic substrate. For 50 samples, the received signal strength indicator, temperature accuracy and statistical distribution of measurement levels is investigated. Comparison of predetermined temperature in a controlled temperature and humidity chamber versus the temperature reading from the developed sensors proves a 99% accuracy.
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- Rydén, Louise, 1975, et al.
(författare)
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Early inflammatory response in soft tissues induced by thin calcium phosphates.
- 2013
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Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 101A:9
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Tidskriftsartikel (refereegranskat)abstract
- The inflammatory response to titanium and hydroxyapatite (HA)-coated titanium in living tissue is controlled by a number of humoral factors, of which monocyte chemoattractant protein-1 (MCP-1) has been specifically linked to the recruitment of monocytes. These cells subsequently mature into tissue-bound macrophages. Macrophages adhering to the proteins adsorbed at the implant surface play a pivotal role in initiating the rejection or integration of the foreign material. Despite this, little is known about the initial inflammatory events that occur in soft tissues following the implantation of titanium and HA-coated titanium implants. In this study, circular discs of commercially pure titanium (c.p. Ti) with either a thin crystalline HA coating or amorphous HA coating or uncoated were implanted subcutaneously into rats. The implants were retrieved after 24 and 72 h. The lactate dehydrogenase (LD) activity, DNA content, expression of MCP-1, interleukin-10 (IL-10), tumor necrosis factor α (TNF-α), as well as monocyte and polymorphonuclear granulocyte counts in the exudate surrounding the implants were analyzed. There were significantly higher DNA and LD levels around the titanium implants at 24 h compared with HA-coated titanium. A rapid decrease in MCP-1 levels was observed for all the implants over the period of observation. No statistically significant differences were found between the two HA-coated implants. Our results suggest a difference in the early soft-tissue response to HA-coated implants when compared with titanium implants, expressed as a downregulation of inflammatory cell recruitment. This suggests that thin HA coatings are promising surfaces for soft tissue applications.
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- Rydén, Louise, 1975, et al.
(författare)
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Inflammatory cell response to ultra-thin amorphous and crystalline hydroxyapatite surfaces
- 2017
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Ingår i: Journal of materials science. Materials in medicine. - : Springer. - 0957-4530 .- 1573-4838. ; 28:1
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that surface modification with a thin hydroxyapatite (HA) coating enhances the osseointegration of titanium implants. However, there is insufficient information about the biological processes involved in the HA-induced response. This study aimed to investigate the inflammatory cell response to titanium implants with either amorphous or crystalline thin HA. Human mononuclear cells were cultured on titanium discs with a machined surface or with a thin, 0.1 mu m, amorphous or crystalline HA coating. Cells were cultured for 24 and 96 h, with and without lipopolysaccharide (LPS) stimulation. The surfaces were characterized with respect to chemistry, phase composition, wettability and topography. Biological analyses included the percentage of implant-adherent cells and the secretion of pro-inflammatory cytokine (TNF-alpha) and growth factors (BMP-2 and TGF-beta 1). Crystalline HA revealed a smooth surface, whereas the amorphous HA displayed a porous structure, at nano-scale, and a hydrophobic surface. Higher TNF-alpha secretion and a higher ratio of adherent cells were demonstrated for the amorphous HA compared with the crystalline HA. TGF-beta 1 secretion was detected in all groups, but without any difference. No BMP-2 secretion was detected in any of the groups. The addition of LPS resulted in a significant increase in TNF-alpha in all groups, whereas TGF-beta 1 was not affected. Taken together, the results show that thin HA coatings with similar micro-roughness but a different phase composition, nano-scale roughness and wettability are associated with different monocyte responses. In the absence of strong inflammatory stimuli, crystalline hydroxyapatite elicits a lower inflammatory response compared with amorphous hydroxyapatite.
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- Rydén, Louise, 1975
(författare)
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On the biological response to different biomaterials under normal and irradiated conditions
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There are several challenges when introducing an implant into a host. Concerning soft tissues, major complications are fibrosis and capsule contracture, whereas for bone, failure of osseointegration may occur. In addition to the properties of the biomaterial, compromising conditions of the host can influence the outcome, and in the case of irradiation, the risk increases for both capsule contracture and failed osseointegration. To improve the success of implants, increased knowledge about the mechanisms of integration is needed. In Study II, in vitro, isolated human mononuclear cells showed increased adhesion to ultrathin amorphous hydroxyapatite (HA)-coated titanium (Ti) and increased secretion of the proinflammatory cytokine TNF-α compared to crystalline HA. No difference between Ti and HA was observed. Study I, in vivo, showed no difference between the HA surfaces, but Ti provoked a more intense inflammatory response in regard to HA. The materials were the same in Studies I and II and had similar microscale topography (Study I: Sa 0.24-0.26 µm; Study II: Sa 0.23-0.3 µm), while amorphous HA was the least hydrophilic (Study II: Ti 60.9°, crystalline HA 58.2°, amorphous HA 89.0°). In Study III, the expression of inflammatory and fibrogenic molecular markers was determined after the insertion of silicone implants in irradiated and nonirradiated human soft tissue. Downregulation of IL-8 and upregulation of BCL-2 were detected in the peri-implant tissue in the irradiated side compared with the nonirradiated side. The antifibrotic transcription factor FOXO1 was downregulated in implant-adherent cells on the irradiated side. Correlation and regression analyses showed that irradiation dose and time since irradiation as well as chemotherapy and anti-neutropenic drugs influenced the gene expression response, both in irradiated and nonirradiated sides. The results of Study IV demonstrated that pre-exposure to irradiation significantly reduced bone-implant contact and implant removal torque in the recipient bone. The irradiation-induced detrimental effects on osseointegration were associated with high expression of proinflammatory TNF-α and osteoclastic CatK and reduced expression of bone formation gene ALP in the implant-adherent cells, in parallel with high expression of the inflammatory cell recruiter MCP-1, proinflammatory TNF-α and pro-fibrotic TGF-β genes in the peri-implant soft tissue. All compartments around the implant in the irradiated site revealed reduced expression of FOXO1. It is concluded that under normal experimental conditions, titanium and ultrathin coated HA are associated with cytocompatibility, biocompatibility and a transient inflammatory process, although differences in surface chemistry, nanotopography and hydrophilicity/hydrophobicity can alter the cellular response. In contrast, irradiation of soft and hard tissues causes dysregulation of biological activities in the different tissue compartments around the implant, of which perturbed inflammation and profibrotic propensity seem to hamper tissue healing and regeneration around implanted biomaterials.
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