In Vitro Knee Wear, Kinematics, and Particle Morphology Among Different Bearing Geometries in a Mobile Bearing Knee System

2011 ◽  
pp. 204-217
Author(s):  
T. M. Grupp ◽  
R. K. Miehlke ◽  
M. Hintner ◽  
J. Schwiesau ◽  
C. Kaddick
Keyword(s):  
Mobile Bearing ◽  
Particle Morphology

In Vitro Knee Wear, Kinematics, and Particle Morphology Among Different Bearing Geometries in a Mobile Bearing Knee System

2011 ◽  
Vol 8 (5) ◽  
pp. 103304 ◽  
Author(s):  
T. M. Grupp ◽  
R. K. Miehlke ◽  
M. Hintner ◽  
J. Schwiesau ◽  
C. Kaddick ◽  
...  
Keyword(s):  
Mobile Bearing ◽  
Particle Morphology

scholarly journals Formulation and evaluation of in-situ gels enriched with Tropicamide loaded solid lipid nanoparticles

2018 ◽  
Vol 9 (1) ◽  
pp. 216
Author(s):  
Jayachandra Reddy Peddappi Reddigari ◽  
Yerikala Ramesh ◽  
Chandrasekhar B. Kothapalli
Keyword(s):  
Solid Lipid Nanoparticles ◽  
Research Work ◽  
Particle Morphology ◽  
Entrapment Efficiency ◽  
Adhesive Force ◽  
Lipid Nanoparticles ◽  
Solid Lipid ◽  
Diffusion Studies

The present research work “Formulation and Evaluation of In-situ gels enriched with Tropicamide loaded solid lipid nanoparticles”. To overcome the problems of side effects and to increase the bioavailability of tropicamide loaded solid lipid nanoparticles are containing with suitable lipids (glycerin trimyristate, Tristearin, Phosphatidylcholine & soyabean lecithin) with stabilizers (poloxamer 188) and surfactant like polysorbate 80. The interaction between drug, lipids & polymer by performing with FTIR no incompatibility with each other. The particle morphology was carried out by SEM & AFM in solid lipid nanoparticle formulation. The particle size was ranges from 213.6 ± 2.16nm to 538.0 ± 6.53 nm. The zeta potential ranges form -18.3mV to 25.6mV. The entrapment efficiency of free tropicamide was ranges from 74.13 % to 90.17%. The drug content was ranges from 0.212mg/ml to 0.912mg/ml. The SLN formulations must be transparent white colour and semi solid consistency. The pH 7.0 to 8.0 in all formulation. The gelling strength of gels TSLNGF1 to TSLNGF12 was ranges from 72 ± 1 sec to 117 ± 2 sec. The bio adhesive force was ranges from 10.12 ±1.01 dynes/cm2 to 23.12 ± 1.91 dynes/cm2. The viscosity of prepared formulation ranges from 415 ± 1.94 cps to 652 ± 1.41 cps. The spread ability studies of all formulation were ranges from 09 gms/sec to 18 gms/sec. The Accelerated stability the formulations does not undergo any chemical Changes. In vitro Franz’s diffusion studies of SLN enriched in gels TSLNGF1 to TSLNGF12 among the various formulation best formulations was TSLNGF6; its follows first order kinetics. Keywords: Solid Lipid Nanoparticles; Tropicamide; In- situ gels; In vitro diffusion studies

scholarly journals The Retroviral Capsid Domain Dictates Virion Size, Morphology, and Coassembly of Gag into Virus-Like Particles

2005 ◽  
Vol 79 (21) ◽  
pp. 13463-13472 ◽  
Author(s):  
Danso Ako-Adjei ◽  
Marc C. Johnson ◽  
Volker M. Vogt
Keyword(s):  
Nuclear Export ◽  
Leukemia Virus ◽  
Particle Diameter ◽  
Particle Morphology ◽  
Structural Protein ◽  
Wild Type ◽  
Virus Like Particles ◽  
Gag Proteins ◽  
Hiv 1

ABSTRACT The retroviral structural protein, Gag, is capable of independently assembling into virus-like particles (VLPs) in living cells and in vitro. Immature VLPs of human immunodeficiency virus type 1 (HIV-1) and of Rous sarcoma virus (RSV) are morphologically distinct when viewed by transmission electron microscopy (TEM). To better understand the nature of the Gag-Gag interactions leading to these distinctions, we constructed vectors encoding several RSV/HIV-1 chimeric Gag proteins for expression in either insect cells or vertebrate cells. We used TEM, confocal fluorescence microscopy, and a novel correlative scanning EM (SEM)-confocal microscopy technique to study the assembly properties of these proteins. Most chimeric proteins assembled into regular VLPs, with the capsid (CA) domain being the primary determinant of overall particle diameter and morphology. The presence of domains between matrix and CA also influenced particle morphology by increasing the spacing between the inner electron-dense ring and the VLP membrane. Fluorescently tagged versions of wild-type RSV, HIV-1, or murine leukemia virus Gag did not colocalize in cells. However, wild-type Gag proteins colocalized extensively with chimeric Gag proteins bearing the same CA domain, implying that Gag interactions are mediated by CA. A dramatic example of this phenomenon was provided by a nuclear export-deficient chimera of RSV Gag carrying the HIV-1 CA domain, which by itself localized to the nucleus but relocalized to the cytoplasm in the presence of wild type HIV-1 Gag. Wild-type and chimeric Gag proteins were capable of coassembly into a single VLP as viewed by correlative fluorescence SEM if, and only if, the CA domain was derived from the same virus. These results imply that the primary selectivity of Gag-Gag interactions is determined by the CA domain.

Balancing mobile-bearing unicondylar knee arthroplasty in vitro

2016 ◽  
Vol 25 (12) ◽  
pp. 3733-3740 ◽  
Author(s):  
Thomas J. Heyse ◽  
Joshua Slane ◽  
Geert Peersman ◽  
Philipp Dworschak ◽  
Susanne Fuchs-Winkelmann ◽  
...  
Keyword(s):  
Knee Arthroplasty ◽  
Mobile Bearing ◽  
Unicondylar Knee Arthroplasty

scholarly journals A Bilayer Vaginal Tablet for the Localized Delivery of Disulfiram and 5-Fluorouracil to the Cervix

Pharmaceutics ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1185
Author(s):  
Ismin Zainol Abidin ◽  
Emanuele Rezoagli ◽  
Bianca Simonassi-Paiva ◽  
Gustavo Waltzer Fehrenbach ◽  
Kevin Masterson ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Low Cost ◽  
Particle Morphology ◽  
Scanning Calorimetry ◽  
Vaginal Tablet ◽  
Weight Variation ◽  
Localized Delivery ◽  
Cervical Tumors ◽  
Cancerous Cells

This study was performed to develop an adjuvant therapy in the form of a self-administered vaginal tablet regimen for the localized delivery of chemotherapeutic drugs. This therapy will help to reduce relapse by eradicating cancerous cells in the margin of cervical tumors. The vaginal tablet is a very common formulation that is easy to manufacture, easy to place in the vagina, and has a low cost of manufacture, making them ideal for use in developing countries. A combination of disulfiram and 5-fluorouracil, which are both off-patent drugs and provide different modes of action, were evaluated. The tablets developed were evaluated for weight variation, thickness, hardness, friability, swelling index, differential scanning calorimetry (DSC), particle morphology, in vitro drug release, and cytotoxicity on Ca-Ski cells. Both layers were designed to release both drugs concurrently for a synergistic effect. The polymer–polymer interaction between the layers was able to reduce the loss of formulation due to chitosan. While the bilayer tablet had satisfactory performance in the physicochemical tests, in vitro cell culture with Ca-Ski also showed a synergistic effect using a combination of drugs at a low dose. However, the formulation only had 24-h dose release before degradation. Further drug combinations should be evaluated in subsequent studies.

scholarly journals Mobile bearing leads to less proximal medial tibial strain following UKA in comparison with fixed bearing in a cadaver setup

2020 ◽  
Vol 8 (5_suppl4) ◽  
pp. 2325967120S0029
Author(s):  
Thomas J. Heyse ◽  
Orcun Taylan ◽  
Joshua Slane ◽  
Harry van Lenthe ◽  
Geert Peersman ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Proximal Tibia ◽  
Infrared Camera ◽  
Mobile Bearing ◽  
Bone Strain ◽  
Fixed Bearing ◽  
Camera System ◽  
Tibial Bone ◽  
Fresh Frozen

Aims and Objectives: Inexplicable pain to the medial proximal tibia is a frequent finding leading to revision after unicondylar knee arthroplasty (UKA). This study is an effort to find out, if there are any differences between mobile (MB) and fixed bearing (FB) UKA designs in terms of resulting strain in the medial proximal tibia as measured in an in vitro cadaver setup. It was hypothesized that MB UKA would result in lower bone strain. Materials and Methods: Five pairs of fresh-frozen full leg cadaver specimens were mounted in a kinematic rig that applied a dynamic squatting motion knee flexion after prior 3D CT. The rig allowed for 6 degrees-of-freedom at the knee while forces were applied to the quadriceps and hamstrings. During testing, an infrared camera system tracked the location of reflective markers attached to the tibia and femur with bicortical bone pins. Tibial cortical bone strain was measured with stacked strain gauge rosettes attached at predefined anterior and posterior positions on the medial cortex. Sensor outputs were recorded at 2000 Hz and synchronized with kinematic data prior and after pairwise implantation of MB and FB UKA directly comparing those between left and right knees from the same donor. Results: Bone strain values consistently increased with increasing flexion angle. FB UKA significantly increased strain in the anterior region of the medial tibial bone, while MB closely replicated strain values of the native knee. Conclusion: Proximal tibial bone strain seems to be lesser following MB UKA in comparison with FB UKA. Clinical studies will have to show, if this translates into a higher rate of pain problems with FB UKA.

In Vitro Study of Backside Wear Mechanisms on Mobile Knee-Bearing Components

2005 ◽  
Vol 128 (2) ◽  
pp. 275-281 ◽  
Author(s):  
S. A. Atwood ◽  
F. E. Kennedy ◽  
J. H. Currier ◽  
D. W. Van Citters ◽  
J. P. Collier
Keyword(s):  
In Vitro Study ◽  
Mobile Bearing ◽  
Porous Coating ◽  
Third Body ◽  
Rotating Platform ◽  
Wear Performance ◽  
Tibial Tray ◽  
Inferior Surface ◽  
Pmma Bone Cement

The long-term success of a total knee replacement depends on the wear performance of a polyethylene bearing that separates a metal femoral component from a metal tibial tray. Although fixed bearing designs secure the polyethylene bearing to the tibial tray, mobile bearing knees allow the polyethylene to move relative to the tibial tray. This study has evaluated the wear performance of an intended articulation on the inferior surface of the LCS®-Rotating Platform mobile bearing by conducting clinically relevant tribological testing and comparing results to retrieved knee bearings. A retrieval analysis leads to the conclusion that third-body particles in the contact produce curvilinear scratches longer than the expected rotation of the knee on both the polyethylene bearing and the CoCr tibial tray. Tribological testing shows that polymethylmethacrylate (PMMA) bone cement particles produce worn surfaces most similar to retrievals. Porous-coating beads and bone debris also have the ability to damage both surfaces. Worn polyethylene surfaces from pin-on-flat tests show scratches longer than the excursion length, and “skipping marks”—pits spaced at smaller rotation intervals along a scratch—as observed in retrievals. These wear features suggest that a ratcheting mechanism, which moves the third-body particles further along the scratch with each cycle, may be responsible for the observed wear.

scholarly journals Knee Wear Assessment: 3D Scanners Used as a Consolidated Procedure

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2349 ◽  
Author(s):  
Saverio Affatato ◽  
Maria Cristina Valigi ◽  
Silvia Logozzo
Keyword(s):  
Clinical Performance ◽  
Wear Behavior ◽  
Wear Test ◽  
Mobile Bearing ◽  
Clinical Problem ◽  
Material Loss ◽  
Optical Scanners ◽  
Wear Rates ◽  
3D Scanners

It is well known that wear occurring in polyethylene menisci is a significant clinical problem. At this regard, wear tests on biomaterials medical devices are performed in order to assess their pre-clinical performance in terms of wear, durability, resistance to fatigue, etc. The objective of this study was to assess the wear of mobile total knee polyethylene inserts after an in vitro wear test. In particular, the wear behavior of mobile bearing polyethylene knee configurations was investigated using a knee joint wear simulator. After the completion of the wear test, the polyethylene mobile menisci were analyzed through a consolidated procedure by using 3D optical scanners, in order to evaluate the 3D wear distribution on the prosthesis surface, wear depths, wear rates, amount of material loss and contact areas. The results in terms of wear rates and wear volumes were compared with results of gravimetric tests, finding equivalent achievements.

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