11,623 research outputs found
Moorfield regression analysis versus retinal nerve fiber layer in glaucoma and ocular hypertension
No full textPurpose: To evaluate the agreement
between Moorfield Regression
Analysis (MRA) and peripapillary
retinal nerve fibers layer thickness.
Methods: 54 eyes with normal VF
and 18 with early VF damage were
classified as ocular hypertension or
early primary open angle glaucoma
(POAG) and were included in the
study: All the subjects performed
achromatic 30° visual field (VF) by
Octopus Program G1X dynamic
strategy and were imaged by HRT 3
and I-Vue OCT. Sectorial and global
MRA and OCT parameters were
used for the analysis. Kappa statistic
was used to assess the agreement
between methods.
Results: A significant agreement
between I-Vue OCT and MRA a
good agreement was shown in the
supero-nasal (κ 0.656) and nasal
(κ 0.627) quadrants followed by the
supero-temporal (κ 0.602) and inferotemporal
(κ 0.586) sectors in all the
eyes studied.
Conclusion: Our results suggest that
the measurements of the ganglion
cells by HRT 3 and I-Vue OCT are not
interchangeable
Comparison between HRT III Glaucoma Probability Score, Moorfields Regression Analysis and the evaluation of nerve fiber layers with OCT i-Vue in patients with ocular hypertension and/or early glaucoma.
No full textValutazione del grado di correlazione tra la MRA (moorfield regression Analysis), il GPS (Glaucoma Probability Score) dell’ HRT III e L’ONH glaucoma analysis dell’OCT i-Vue.
No full textEvaluation of agreement between HRT III and iVue OCT in Glaucoma and Ocular Hypertension patients.
No full textPurpose. To determine the agreement between Moorfields Regression Analysis (MRA), Glaucoma Probability Score (GPS) of Heidelberg retinal tomograph (HRT III), and peripapillary nerve fibers thickness by iVue Optical Coherence Tomography (OCT). Methods. 72 eyes with ocular hypertension or primary open angle glaucoma (POAG) were included in the study: 54 eyes had normal visual fields (VF) and 18 had VF damage. All subjects performed achromatic 30° VF by Octopus Program G1X dynamic strategy and were imaged with HRT III and iVue OCT. Sectorial and global MRA, GPS, and OCT parameters were used for the analysis. Kappa statistic was used to assess the agreement between methods. Results. A significant agreement between iVue OCT and GPS for the inferotemporal quadrant (κ: 0.555) was found in patients with abnormal VF. A good overall agreement between GPS and MRA was found in all the eyes tested (κ: 0.511). A good agreement between iVue OCT and MRA was shown in the superonasal (κ: 0.656) and nasal (κ: 0.627) quadrants followed by the superotemporal (κ: 0.602) and inferotemporal (κ: 0.586) sectors in all the studied eyes. Conclusion. The highest percentages of agreement were found per quadrant of the MRA and the iVue OCT confirming that in glaucoma damage starts from the temporal hemiretina
Ocular Inflammation: Can It Be a Sign of Activity of Weber-Christian Disease? A Case Report and Review of Literature.
No full textValutazione della concordanza tra la Moorfield Regression Analysis (MRA), il Glaucoma Probability Score (GPS) dell'HRT III e L'ONH glacoma analysis dell'OCT i-Vue
No full text
Study on the Mg-Li-Zn ternary alloy system with improved mechanical properties, good degradation performance and different responses to cells
No full textNovel Mg-(3.5, 6.5wt%)Li-(0.5, 2, 4wt%)Zn ternary alloys were developed as new kinds of biodegradable metallic materials with potential for stent application. Their mechanical properties, degradation behavior, cytocompatibility and hemocompatibility were studied. These potential biomaterials showed higher ultimate tensile strength than previously reported binary Mg-Li alloys and ternary Mg-Li-X (X=Al, Y, Ce, Sc, Mn and Ag) alloys. Among the alloys studied, the Mg-3.5Li-2Zn and Mg-6.5Li-2Zn alloys exhibited comparable corrosion resistance in Hank's solution to pure magnesium and better corrosion resistance in a cell culture medium than pure magnesium. Corrosion products observed on the corroded surface were composed of Mg(OH)2, MgCO3 and Ca-free Mg/P inorganics and Ca/P inorganics. In vitro cytotoxicity assay revealed different behaviors of Human Umbilical Vein Endothelial Cells (HUVECs) and Human Aorta Vascular Smooth Muscle Cells (VSMCs) to material extracts. HUVECs showed increasing nitric oxide (NO) release and tolerable toxicity, whereas VSMCs exhibited limited decreasing viability with time. Platelet adhesion, hemolysis and coagulation tests of these Mg-Li-Zn alloys showed different degrees of activation behavior, in which the hemolysis of the Mg-3.5Li-2Zn alloy was lower than 5%. These results indicated the potential of the Mg-Li-Zn alloys as good candidate materials for cardiovascular stent applications. Statement of significance: Mg-Li alloys are promising as absorbable metallic biomaterials, which however have not received significant attention since the low strength, controversial corrosion performance and the doubts in Li toxicity. The Mg-Li-Zn alloy in the present study revealed much improved mechanical properties higher than most reported binary Mg-Li and ternary Mg-Li-X alloys, with superior corrosion resistance in cell culture media. Surprisingly, the addition of Li and Zn showed increased nitric oxide release. The present study indicates good potential of Mg-Li-Zn alloy as absorbable cardiovascular stent material.Accepted Author ManuscriptBiomaterials & Tissue Biomechanic
“Mg” Bone: Ink extrusion-based additive manufacturing of Mg implants
No full textThe treatment of largy bone defect remains challenging in clinics. All the clinically available bone grafts have their own limitations and are not ideal for the treatment. Therefore, developing a new generation of suitable bone substitutes is urgently needed. In the recent years, porous magnesium (Mg) has been extensively studied for orthopedic applications owing to its biodegradability, favorable mechanical properties, and osteopromotive ability. The recent advances in additive manufacturing (AM) provide unprecedented opportunities to design and fabricate porous Mg scaffolds with interconnected porous structures that are favorable for the adhesion and proliferation of bone cells. However, powder bed fusion AM, which is the most commonly used AM technique for fabricating metal structures, has encountered many difficulties in manufacturing Mg due to safety concerns, excessive oxidation, and undesirable compositional variation due to the low boiling temperature of Mg. To alleviate these difficulties, alternative AM techniques that can create highly porous structures at room temperature are highly sought after. The aim of this research was to develop a room-temperature AM technique for manufacturing porous Mg and to characterize the fabricated Mg-based scaffolds in different aspects relevant to their potential applications as bone implants.In this thesis work, we, for the first time, successfully employed extrusion-based 3D printing techniques to fabricate biodegradable porous Mg and Mg-based scaffolds for application in orthopedics. We started with the optimization of the formulated binder system, the printing process, and the subsequent liquid-phase sintering process for the AM of Mg and Mg-based scaffolds. On this basis, a series of Mg and Mg-based porous scaffolds, including Mg alloy and Mg matrix composite scaffolds were successfully fabricated. Then, we conducted comprehensive studies on the microstructure, geometrical characteristics, in vitro biodegradation behavior, mechanical properties, and the in vitro biodegradation and the responses of preosteoblast MC3T3-E1 cells to the fabricated scaffolds to evaluate the ability of the fabricated scaffolds to satisfy the requirements of ideal bone-substituting biomaterials. By modifying the alloy composition and adding bioceramic components, the properties of the Mg scaffolds required were significantly improved as compared to those of the pure Mg specimens. The fabricated Mg-matrix composite scaffolds were shown to be the most promising materials to be further developed for bone substitution. Surface modification could also contribute to bringing the fabricated Mg scaffolds closer to meeting the requirements. Therefore, with proper material design and surface modification, the Mg-based scaffolds fabricated using extrusion-based 3D printing technique constitute a new category of porous Mg-based biomaterials that hold great promise for application as bone substitutes
Extrusion-based additive manufacturing of Mg-Zn alloy scaffolds
No full textPorous biodegradable Mg and its alloys are considered to have a great potential to serve as ideal bone substitutes. The recent progress in additive manufacturing (AM) has prompted its application to fabricate Mg scaffolds with geometrically ordered porous structures. Extrusion-based AM, followed by debinding and sintering, has been recently demonstrated as a powerful approach to fabricating such Mg scaffolds, which can avoid some crucial problems encountered when applying powder bed fusion AM techniques. However, such pure Mg scaffolds exhibit a too high rate of in vitro biodegradation. In the present research, alloying through a pre-alloyed Mg-Zn powder was ultilized to enhance the corrosion resistance and mechanical properties of AM geometrically ordered Mg-Zn scaffolds simultaneously. The in vitro biodegradation behavior, mechanical properties, and electrochemical response of the fabricated Mg-Zn scaffolds were evaluated. Moreover, the response of preosteoblasts to these scaffolds was systematically evaluated and compared with their response to pure Mg scaffolds. The Mg-Zn scaffolds with a porosity of 50.3% and strut density of 93.1% were composed of the Mg matrix and MgZn2 second phase particles. The in vitro biodegradation rate of the Mg-Zn scaffolds decreased by 81% at day 1, as compared to pure Mg scaffolds. Over 28 days of static immersion in modified simulated body fluid, the corrosion rate of the Mg-Zn scaffolds decreased from 2.3 ± 0.9 mm/y to 0.7 ± 0.1 mm/y. The yield strength and Young's modulus of the Mg-Zn scaffolds were about 3 times as high as those of pure Mg scaffolds and remained within the range of those of trabecular bone throughout the biodegradation tests. Indirect culture of MC3T3-E1 preosteoblasts in Mg-Zn extracts indicated favorable cytocompatibility. In direct cell culture, some cells could spread and form filopodia on the surface of the Mg-Zn scaffolds. Overall, this study demonstrates the great potential of the extrusion-based AM Mg-Zn scaffolds to be further developed as biodegradable bone-substituting biomaterials.Biomaterials & Tissue BiomechanicsTeam Peyman TaheriTeam Arjan Mo
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