Microstructural Factors in Neocartilage Function

2000 ◽  
Author(s):  
Jack L. Lewis
Keyword(s):  
Mechanical Properties ◽  
Materials Science ◽  
Clinical Performance ◽  
Theoretical Models ◽  
Biological Properties ◽  
Activity Level ◽  
Matrix Assembly ◽  
Highly Active ◽  
Culturing Conditions

Abstract Tissue engineering of cartilage and other connective tissues is a highly active area of research, motivated by the considerable medical need and commercial potential. Tissue with biological properties and biochemical composition similar to cartilage have been generated in laboratory cultures and animal models, and one method is being used in patients. Throughout the early development of regenerated cartilage, the focus has been on getting something to grow that is biochemically like cartilage and fills defects with tissue that visually looks like cartilage and holds up mechanically over the short term. The issues of cell source, culturing conditions, and scaffolds have also been addressed. However, all of the tissues generated have structure and microstructural organization that are not like natural cartilage. Although the clinical performance of the regenerated tissue appears promising, experience with prior regenerated tissue and the fact that the tissue is abnormal gives concern about the long term performance of the regenerated cartilage and the influence of activity level on this performance. Its long term mechanical properties are suspected to be inadequate. Future developments in this area will need to both enhance the mechanical characteristics of the regenerated tissue and develop methods and criteria for evaluating the tissue that is generated. Our work on matrix assembly by chondrocytes has been directed towards these ends. The goal has been to understand the microstructural basis for mechanical properties in tissue generated by chondrocytes in culture, develop methods to alter and control the microstructure, and build both experimental and theoretical models that allow evaluating the connection between microstructure and macroscopic properties. This is similar to a materials science approach which, we believe, will be one approach to the second generation of engineered tissues. The approach and results to date on tissue generated by chondrocytes will be described in this presentation. A specific question related to collagen network microstructure will be used to illustrate this approach.

Surface Corrosion of Nanoscaled Hydroxyapatite During an In Vivo Experiment

2015 ◽  
Vol 15 (10) ◽  
pp. 7976-7979 ◽  
Author(s):  
Dong Seok Seo ◽  
Jong Kook Lee ◽  
Kyu Hong Hwang
Keyword(s):  
Mechanical Properties ◽  
Grain Boundary ◽  
Biological Properties ◽  
Implant Surface ◽  
Particle Generation ◽  
Surface Corrosion ◽  
Osteoclast Resorption ◽  
Hydroxyapatite Implant

Hydroxyapatite (HA) is widely used as a bioactive ceramics as it forms a chemical bond with bone. However, the drawback to using this material is its inferior mechanical properties. In this research, surface corrosion and disintegration of nanoscaled HA in a dog were studied, and the mechanism by which phase-pure HA dissolved In Vivo was investigated. Biological properties of HA In Vivo are affected by the grain-boundary dissolution followed by a surface corrosion and microstructural disintegration. This kind of dissolution process, apparently evidenced at the grain boundary, causes particle generation, which indicates that both long-term bone in-growth and mechanical properties can dramatically deteriorate. Implant dissolution by osteoclasts In Vivo is also observed on the surface of hydroxyapatite. Implant surface showed an aggressive corrosion by an osteoclast resorption. Severe and deeper dissolution underwent close to osteoclast resulting in formation of smaller and more round particle shape.

Ceramics in dentistry: which material is appropriate for the anterior or posterior Dentition? Part 1: materials science

Dental Update ◽  
2021 ◽  
Vol 48 (8) ◽  
pp. 680-688
Author(s):  
Loo Chien Win ◽  
Peter Sands ◽  
Stephen J Bonsor ◽  
FJ Trevor Burke
Keyword(s):  
Mechanical Properties ◽  
Clinical Research ◽  
Physical Properties ◽  
Ceramic Material ◽  
Clinical Relevance ◽  
Materials Science ◽  
Clinical Performance ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Posterior Teeth

The large choice of ceramic materials for an indirect restoration has given clinicians a dilemma when choosing a suitable ceramic for restorations in anterior or posterior teeth. Focusing principally on the most commonly used materials, lithium disilicate and zirconia, the aim of Part 1 of this article is to compare the mechanical properties and aesthetics of these two materials. For strength, zirconia possesses superior physical properties when compared with lithium disilicate. However, in terms of aesthetics, lithium disilicate holds advantages. With both materials having different microstructures, the same cementation protocols cannot be used. Other contemporary ceramic materials are briefly reviewed. Part 2 reviews the latest clinical research on their clinical performance. CPD/Clinical Relevance: Awareness of which ceramic material performs optimally on anterior and posterior teeth is clinically important.

scholarly journals Stability and plasticity of contextual modulation in the mouse visual cortex

2016 ◽  
Author(s):  
Adam Ranson
Keyword(s):  
Visual Cortex ◽  
Activity Level ◽  
Visual Context ◽  
Contextual Modulation ◽  
Long Term Stability ◽  
Highly Active ◽  
Primary Sensory Cortex ◽  
Excitatory Neurons ◽  
Mouse Visual Cortex

SummaryActivity of neurons in primary sensory cortex is shaped by visual and behavioural context. However the long-term stability of the influence of contextual factors in the mature cortex remains poorly understood. To investigate this we used 2-photon calcium imaging to track the influence of surround suppression and locomotion on individual neurons over 14 days. We found that highly active excitatory neurons and PV+ interneurons exhibited relatively stable modulation by visual context. Similarly most neurons exhibited a stable yet distinct degree modulation by locomotion. In contrast less active excitatory neurons exhibited plasticity in visual context influence resulting in increased suppression. These findings suggest that the mature visual cortex possesses stable subnetworks of neurons, differentiated by cell-type and activity level, which have distinctive and stable interactions with sensory and behavioural context, as well as other less active and more labile neurons which are sensitive to visual experience.

Manufacturing, oxidation, mechanical properties and clinical performance of highly cross-linked polyethylene in total hip arthroplasty

2018 ◽  
Vol 28 (6) ◽  
pp. 573-583 ◽  
Author(s):  
Gurpreet Singh ◽  
Robert Klassen ◽  
James Howard ◽  
Douglas Naudie ◽  
Matthew Teeter ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
First Generation ◽  
Clinical Performance ◽  
Wear Rates ◽  
Total Hip ◽  
Uhmwpe Wear

Ultra-high molecular weight polyethylene (UHMWPE) continues to be the gold standard bearing surface in total hip arthroplasty (THA) for nearly 5 decades. Highly cross-linked UHMWPE (HXLPE) was adapted for routine use in the early 2000s to reduce the revision rates related to wear, osteolysis, and aseptic loosening resulting from conventional UHMWPE wear. Since its inception, consistent evidence showing reduced wear rates and osteolysis supports the use of HXLPE in THA. High quality studies demonstrating the advantage in long term survivorship of HXLPE over conventional UHMWPE are emerging. Though retrieval studies have demonstrated evidence of in vivo oxidation and fatigue related damage at the rim of the first generation HXLPE liners, clinical significance of this remains to be seen. Second-generation sequentially annealed and vitamin E containing HXLPE liners demonstrate improved mechanical properties, resistance to oxidation, and equivalent wear rates in comparison to their first-generation counterparts, but long term success remains to be seen.

scholarly journals One-year clinical performance of lithium disilicate versus resin composite CAD/CAM onlays

Odontology ◽  
2020 ◽  
Vol 109 (1) ◽  
pp. 259-270
Author(s):  
Joana Souza ◽  
Mª Victoria Fuentes ◽  
Eugenia Baena ◽  
Laura Ceballos
Keyword(s):  
Clinical Performance ◽  
Resin Composite ◽  
Oral Care ◽  
Lithium Disilicate ◽  
Biological Properties ◽  
Color Match ◽  
Posterior Teeth ◽  
Cad Cam ◽  
One Year

AbstractTo compare the 1-year clinical performance of lithium disilicate and resin composite CAD/CAM onlay restorations. Twenty patients that required two restorations in posterior teeth, with at least one cusp to be covered, received two onlays. One was made with IPS e.max CAD (Ivoclar-Vivadent) and the other with Lava Ultimate (3M Oral Care). Two blind observers evaluated the restorations at baseline and 1 year after the onlays were cemented, according to FDI criteria. At each recall, digital photographs, bite-wing radiographs and impressions of the restorations were taken for SEM evaluation of the interface. Results were analyzed by Mann–Whitney U and Wilcoxon tests (p < 0.05). At baseline and in the 1-year recall, both CAD/CAM materials exhibited excellent results in most criteria with similar esthetic, functional and biological properties (p > 0.05). However, deterioration in surface lustre (p = 0.020) and color match/translucency (p = 0.039) were detected for IPS e.max CAD onlays after 1-year. Under SEM evaluation, there were no statistically differences in micromorphological criteria at baseline nor after a year between IPS e.max CAD and Lava Ultimate onlays. Conclusion: After 1 year of clinical service IPS e.max CAD and Lava Ultimate onlays showed a similar clinical performance that needs to be confirmed in long-term evaluations.

Antiretroviral Treatment-Associated Labia Majora Lipohypertrophy: A Rare Case and Plastic Surgical Treatment Options

2017 ◽  
Vol 2 (1) ◽  
pp. 43
Author(s):  
Akmal Hisham ◽  
Devananthan Ilenghoven ◽  
Wan Syazli Wan Ahmad Kamal ◽  
Salina Ibrahim ◽  
Shah Jumaat Mohd Yussof
Keyword(s):  
Highly Active Antiretroviral Therapy ◽  
Daily Living ◽  
Treatment Options ◽  
Hiv Positive ◽  
Highly Active ◽  
Labia Majora ◽  
The Face ◽  
Central Fat

The emergence of highly active antiretroviral therapy (HAART) has revolutionized the prognosis of HIV-infected patients. However, the extended use of HAART is associated with a disfiguring complication termed lipodystrophy, a disorder of body fat maldistribution causing peripheral fat loss (lipoatrophy) and central fat accumulation (lipohypertrophy). Lipoatrophy commonly affects the face, legs, buttocks and arm, whilst lipohypertrophy frequently favours the abdomen, breast and dorsocervical region. To our knowledge, we present only the second documented case in the literature of a labia majora lipohypertrophy in a HIV-positive patient receiving long-term HAART. The severity of labial abnormality caused significant physical and functional morbidities. Labiaplasty with dermolipectomy of the labia majora and excisional lipectomy of the mons pubis was successfully performed. At a 6-month follow-up, patient had no recurrence with resolution of symptoms and resumption of normal activities of daily living (ADL).

The Molecular Diversity Scope of Urazole in the Synthesis of Organic Compounds

2019 ◽  
Vol 16 (7) ◽  
pp. 953-967 ◽  
Author(s):  
Ghodsi M. Ziarani ◽  
Fatemeh Mohajer ◽  
Razieh Moradi ◽  
Parisa Mofatehnia
Keyword(s):  
Biological Activities ◽  
Biological Properties ◽  
Biologically Active ◽  
Microtubule Assembly ◽  
Heterocyclic Molecules ◽  
Biological Perspective ◽  
Highly Active ◽  
Anti Inflammatory ◽  
High Yields ◽  
Short Time

Background: As a matter of fact, nitrogen as a hetero atom among other atoms has had an important role in active biological compounds. Since heterocyclic molecules with nitrogen are highly demanded due to biological properties, 4-phenylurazole as a compound containing nitrogen might be important in the multicomponent reaction used in agrochemicals, and pharmaceuticals. Considering the case of fused derivatives “pyrazolourazoles” which are highly applicable because of their application for analgesic, antibacterial, anti-inflammatory and antidiabetic activities as HSP-72 induction inhibitors (I and III) and novel microtubule assembly inhibitors. It should be mentioned that spiro-pyrazole also has biological activities like cytotoxic, antimicrobial, anticonvulsant, antifungal, anticancer, anti-inflammatory, and cardiotonic activities. Objective: Urazole has been used in many heterocyclic compounds which are valuable in organic syntheses. This review disclosed the advances in the use of urazole as the starting material in the synthesis of various biologically active molecules from 2006 to 2019. Conclusion: Compounds of urazole (1,2,4-triazolidine-3,5-dione) are the most important molecules which are highly active from the biological perspective in the pharmaceuticals as well as polymers. In summary, many protocols for preparations of the urazole derivatives from various substrates in multi-component reactions have been reported from different aromatic and aliphatic groups which have had carbonyl groups in their structures. It is noted that several catalysts have been synthesized to afford applicable molecules with urazole scaffolds. In some papers, being environmentally friendly, short time reactions and high yields are highlighted in the protocols. There is a room to synthesize new catalysts and perform new reactions by manipulating urazole to produce biologically active compounds, even producing chiral urazole component as many groups of chiral urazole compounds are important from biological perspective.

Emotion Dysregulation in Autism Spectrum Disorder

2018 ◽  
pp. 282-298
Author(s):  
Emily Neuhaus
Keyword(s):  
Autism Spectrum Disorder ◽  
Social Communication ◽  
Educational Outcomes ◽  
Emotion Dysregulation ◽  
Research Priorities ◽  
Theoretical Models ◽  
Autism Spectrum ◽  
Repetitive Behaviors ◽  
Spectrum Disorder

Autism spectrum disorder (ASD) is defined by deficits in social communication and interaction, and restricted and repetitive behaviors and interests. Although current diagnostic conceptualizations of ASD do not include emotional difficulties as core deficits, the disorder is associated with emotion dysregulation across the lifespan, with considerable implications for long-term psychological, social, and educational outcomes. The overarching goal of this chapter is to integrate existing knowledge of emotion dysregulation in ASD and identify areas for further investigation. The chapter reviews the prevalence and expressions of emotion dysregulation in ASD, discusses emerging theoretical models that frame emotion dysregulation as an inherent (rather than associated) feature of ASD, presents neurobiological findings and mechanisms related to emotion dysregulation in ASD, and identifies continuing controversies and resulting research priorities.

Ultrasonic Torsion Welding of Aging Resistant Al/CFRP Joints - Concepts, Mechanical and Microstructural Properties

2017 ◽  
Vol 742 ◽  
pp. 395-400 ◽  
Author(s):  
Florian Staab ◽  
Frank Balle ◽  
Johannes Born
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Materials Science ◽  
Dissimilar Materials ◽  
Material Design ◽  
Ultrasonic Welding ◽  
Fatigue Properties ◽  
Aviation Industry ◽  
Efficient Design ◽  
Engineering Structures

Multi-material-design offers high potential for weight saving and optimization of engineering structures but inherits challenges as well, especially robust joining methods and long-term properties of hybrid structures. The application of joining techniques like ultrasonic welding allows a very efficient design of multi-material-components to enable further use of material specific advantages and are superior concerning mechanical properties.The Institute of Materials Science and Engineering of the University of Kaiserslautern (WKK) has a long-time experience on ultrasonic welding of dissimilar materials, for example different kinds of CFRP, light metals, steels or even glasses and ceramics. The mechanical properties are mostly optimized by using ideal process parameters, determined through statistical test planning methods.This gained knowledge is now to be transferred to application in aviation industry in cooperation with CTC GmbH and Airbus Operations GmbH. Therefore aircraft-related materials are joined by ultrasonic welding. The applied process parameters are recorded and analyzed in detail to be interlinked with the resulting mechanical properties of the hybrid joints. Aircraft derived multi-material demonstrators will be designed, manufactured and characterized with respect to their monotonic and fatigue properties as well as their resistance to aging.

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