14 results on '"Oloyede, Adekunle"'
Search Results
2. A new mechanical indentation framework for functional assessment of articular cartilage.
- Author
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Arabshahi, Zohreh, Afara, Isaac Oluwaseun, Moody, Hayley Ruscoe, Schrobback, Karsten, Kashani, Jamal, Fischer, Nadine, Oloyede, Adekunle, and Klein, Travis Jacob
- Subjects
ARTICULAR cartilage ,JOINT stiffness ,GLYCAN structure ,SWELLING of materials ,MULTIVARIATE analysis - Abstract
The conventional mechanical properties of articular cartilage, such as compressive stiffness, have been shown to have limited capacity to distinguish visually normal from degraded cartilage samples. In this study, a new mechanical indentation framework for assessing functional properties of articular cartilage during loading/unloading, i.e. deformation and recovery, was established. The capacity of a ring-shaped indenter integrated with an ultrasound transducer to distinguish mechanically intact from proteoglycan-depleted tissue was investigated. To achieve this, normal and enzymatically degraded bovine osteochondral samples were subjected to loading/unloading while the response of the tissue at the middle was captured by ultrasound at the same time. The enzymatic degradation model was characterized by amount of proteoglycan content, glycosaminoglycan release and proteomic analysis. The mechanical response of a wider continuum of articular cartilage in the loaded area and its surrounding region was captured in this framework leading to investigate two parameters, L and TS, related to the surrounding tissue of the loaded area for functional assessment of cartilage. L is the distance between the ultrasound transducer and articular cartilage surface and TS is the transient strain of articular cartilage during loading and unloading. Classification Analysis based on Principal Component Analysis was used to investigate the capacity of the new parameters to assess the functionality of the tissue. Multivariate statistics based on Partial Least Squares regression was employed to identify the correlation between the response of the tissue in the indented area and its surrounding cartilage. The results of this study indicate that L during loading (deformation) can differentiate normal and mildly proteoglycan-depleted samples from severely depleted samples and L during unloading (recovery) can distinguish between normal and proteoglycan-depleted tissue. However, TS during deformation and recovery is unable to discriminate normal cartilage samples from proteoglycan-depleted tissue. The results also demonstrate a strong correlation between mechanical properties of the loaded area with the response of its surrounding cartilage during recovery. It is therefore concluded that L in this newly established framework can discriminate between normal and proteoglycan-depleted cartilage samples. However, more samples will be needed to verify the demarcation between samples degraded for varying amount of time. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
3. Preliminary characterisation of the surface of cartilage following exposure to saturated and unsaturated synthetic lipids
- Author
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Yusuf, Kehinde Quasim, Gudimetla, Prasad, Pawlak, Zenon, and Oloyede, Adekunle
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090305 Rehabilitation Engineering ,Surface Amorphous Layer ,Load Bearing ,Relipidization ,Lubrication ,AFM ,Articular Cartilage ,Delipidization - Abstract
Articular cartilage is covered by a microscopic structure known as surface amorphous layer. This surface structure is often the first victim of attack during cartilage degeneration, thereby resulting in a gross impairment in cartilage function such as lubrication and load bearing. We hypothesize that incubation of degraded cartilage in solutions of different species of synthetic surface active phospholipids (saturated and unsaturated species) can remodel this lost surface structure. To test this hypothesis, the structural configuration of the surface of articular cartilage was studied and characterised with the lipid filled surface amorphous layer intact using the AFM. The results were then compared with those obtained following a systematic removal (delipidization) and replacement (relipidization) of this layer. Our results show that the unsaturated surfactant partially restored the lost surface amorphous layer while the saturated surfactant specie settled on the surface due to its poor solubility in aqueous solution.
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- 2011
4. Optical non-destructive evaluation of articular cartilage integrity : a review
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Afara, Isaac O., Pawlak, Zenon, and Oloyede, Adekunle
- Subjects
Near Infrared (NIR) ,090399 Biomedical Engineering not elsewhere classified ,Infrared (IR) ,090303 Biomedical Instrumentation ,090304 Medical Devices ,Spectroscopy ,Articular Cartilage - Abstract
This paper reviews the current status of the application of optical non-destructive methods, particularly infrared (IR) and near infrared (NIR), in the evaluation of the physiological integrity of articular cartilage. It is concluded that a significant amount of work is still required in order to achieve specificity and clinical applicability of these methods in the assessment and treatment of dysfunctional articular joints.
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- 2011
5. Near-infrared (NIR) spectroscopic evaluation of articular cartilage: A review of current and future trends.
- Author
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Olumegbon, Ismail Adewale, Oloyede, Adekunle, and Afara, Isaac Oluwaseun
- Subjects
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NEAR infrared spectroscopy , *SPECTRUM analysis , *DECISION making , *DEGENERATION (Pathology) , *ARTICULAR cartilage - Abstract
This review describes recent developments and applications of near-infrared (NIR) spectroscopy for characterization of articular cartilage integrity. It summarizes the research findings in this area and presents some spectral ranges and peaks associated with the different properties and components of articular cartilage. We further describe recent adaptations of NIR spectroscopy for clinical evaluation of articular cartilage injury and degeneration. Critical to accurate decision-making during repair surgery is having clear knowledge of lesion severity and spread, and how to grade the quality of surrounding cartilage. Thus, in this review, we detail efforts aimed at quantification and classification of cartilage pathology using NIR spectroscopy. Finally, we present open questions and challenges with a view to guiding future directions in NIR spectroscopy research on articular cartilage. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
6. New directions for the characterisation of cartilage health in vivo
- Author
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Brown, Cameron P., Oloyede, Adekunle, Moody, Hayley R., and Crawford, Ross W.
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osteoarthritis ,090399 Biomedical Engineering not elsewhere classified ,arthroscopic indentation ,tangential surface strain ,articular cartilage ,110314 Orthopaedics - Abstract
This paper outlines the motivation and preliminary investigations into the possibility of a new method of characterising cartilage health in vivo. Current in vivo indentation techniques, which rely on stiffness measurements alone, are unable to adequately distinguish between healthy and degraded tissue. By considering the tangential strain in the articular surface during an indentation test, it is hypothesised that a simple and more sensitive indicator of cartilage integrity may be possible. The present study investigates the effects of low levels of degradation on the tangential surface strain under the indenter. Preliminary results suggest that this technique is highly sensitive, and can discriminate between degeneration and the natural variations across the joint. From these investigations we propose that the relationship between indentation and the surrounding strain field might be able to distinguish between healthy soft tissue and degraded tissue in vivo, important information not available from the current techniques. This study forms the basis of a series of further experimental and modelling investigations to develop these ideas with the goal of creating a more effective diagnostic method for the surgeon.
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- 2005
7. Simultaneous Magnetic Resonance Imaging and Consolidation Measurement of Articular Cartilage.
- Author
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Wellard, Robert Mark, Ravasio, Jean-Philippe, Guesne, Samuel, Bell, Christopher, Oloyede, Adekunle, Tevelen, Greg, Pope, James M., and Momot, Konstantin I.
- Subjects
INTERFEROMETERS ,TISSUES ,ARTICULAR cartilage ,MAGNETIC resonance imaging ,MAGNETIC fields ,OPTICAL fiber detectors - Abstract
Magnetic resonance imaging (MRI) offers the opportunity to study biological tissues and processes in a non-disruptive manner. The technique shows promise for the study of the load-bearing performance (consolidation) of articular cartilage and changes in articular cartilage accompanying osteoarthritis. Consolidation of articular cartilage involves the recording of two transient characteristics: the change over time of strain and the hydrostatic excess pore pressure (HEPP). MRI study of cartilage consolidation under mechanical load is limited by difficulties in measuring the HEPP in the presence of the strong magnetic fields associated with the MRI technique. Here we describe the use of MRI to image and characterize bovine articular cartilage deforming under load in an MRI compatible consolidometer while monitoring pressure with a Fabry-Perot Interferometer-based fiber-optic pressure transducer. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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8. The role of lamellate phospholipid bilayers in lubrication of joints.
- Author
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PAWLAK, ZENON, URBANIAK, WIESŁAW, GADOMSKI, ADAM, YUSUF, KEHINDE Q., AFARA, ISAAC O., and OLOYEDE, ADEKUNLE
- Subjects
BILAYER lipid membranes ,ARTICULAR cartilage ,LUBRICATION & lubricants ,JOINT physiology ,WETTING ,LIPIDS - Abstract
This study aims to determine the effect of progressive loss of the surface active phospholipids on the characteristics, and hence tribological function of articular cartilage. In accordance to Hill's hypothesis, 3-7 lipid bilayers at pH 7.4 operate as the solid lubricant in the cartilage-cartilage interface during physiological function. These bilayers are known to be depleted during cartilage degeneration. This study models this loss of phospholipid bilayers, studying experimentally both wet and dry cartilage surfaces, measuring surface wettability, and friction coefficient under a constant stress of 1.2 MPa. The results demonstrate that the friction coefficient increases gradually with loss of the phospholipid bilayers, and gains in value with decrease in wettability. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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9. A Microanalytical Study of the Surfaces of Normal, Delipidized, and Artificially 'Resurfaced' Articular Cartilage.
- Author
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Yusuf, Kehinde Quasim, Motta, Nunzio, Pawlak, Zenon, and Oloyede, Adekunle
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MICROCHEMISTRY ,BIOLOGICAL interfaces ,ARTICULAR cartilage ,MICROSCOPICAL technique ,PHOSPHOLIPIDS ,OSTEOARTHRITIS - Abstract
The surface amorphous layer of articular cartilage is of primary importance to its load-bearing and lubrication function. This lipid-filled layer is degraded/disrupted or eliminated when cartilage degenerates due to diseases. This article examines further the characteristic of this surface overlay using a combination of microscopy and imaging methods to evaluate the hypothesis that the surface of articular cartilage can be repaired by exposing degraded cartilage to aqueous synthetic lipid mixtures. The preliminary results demonstrate that it is possible to create a new surface layer of phospholipids on the surface of cartilage following artificial lipid removal, but such a layer does not possess enough mechanical strength for physiological function when created with either unsaturated palmitoyl-oleoyl-phosphatidylcholine or saturated dipalmitoyl-phosphatidylcholine component of joint lipid composition alone. We conclude that this may be due to low structural cohesivity, inadequate time of exposure, and the mix/content of lipid in the incubation environment. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
10. Conceptualisation of articular cartilage as a giant reverse micelle: A hypothetical mechanism for joint biocushioning and lubrication
- Author
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Pawlak, Zenon and Oloyede, Adekunle
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ARTICULAR cartilage , *REVERSED micelles , *JOINTS (Anatomy) , *PHOSPHOLIPIDS , *BIOLOGICAL models , *ELECTROKINETICS - Abstract
Abstract: Phospholipid (PL) molecules form the main structure of the membrane that prevents the direct contact of opposing articular cartilage layers. In this paper we conceptualise articular cartilage as a giant reverse micelle (GRM) in which the highly hydrated three-dimensional network of phospholipids is electrically charged and able to resist compressive forces during joint movement, and hence loading. Using this hypothetical base, we describe a hydrophilic–hydrophilic (HL–HL) biopair model of joint lubrication by contacting cartilages, whose mechanism is reliant on lamellar cushioning. To demonstrate the viability of our concept, the electrokinetic properties of the membranous layer on the articular surface were determined by measuring via microelectrophoresis, the adsorption of ions H, OH, Na and Cl on phospholipid membrane of liposomes, leading to the calculation of the effective surface charge density. The surface charge density was found to be −0.08±0.002cm−2 (mean±S.D.) for phospholipid membranes, in 0.155M NaCl solution and physiological pH. This value was approximately five times less than that measured in 0.01M NaCl. The addition of synovial fluid (SF) to the 0.155M NaCl solution reduced the surface charge density by 30% which was attributed to the binding of synovial fluid macromolecules to the phospholipid membrane. Our experiments show that particles charge and interact strongly with the polar core of RM. We demonstrate that particles can have strong electrostatic interactions when ions and macromolecules are solubilized by reverse micelle (RM). Since ions are solubilized by reverse micelle, the surface entropy influences the change in the charge density of the phospholipid membrane on cartilage surfaces. Reverse micelles stabilize ions maintaining equilibrium, their surface charges contribute to the stability of particles, while providing additional screening for electrostatic processes. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
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11. Ultrasound Assessment of Articular Cartilage: Analysis of the Frequency Profile of Reflected Signals from Naturally and Artificially Degraded Samples.
- Author
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Brown, Cameron P., Hughes, Stephen W., Crawford, Ross W., and Oloyede, Adekunle
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ARTICULAR cartilage ,RESONANT ultrasound spectroscopy ,COLLAGEN ,CONNECTIVE tissues ,PROTEOGLYCANS - Abstract
This article investigates in vitro the hypothesis that the frequency profile of ultrasound reflections may be used to characterize degradation and osteoarthritic progression in articular cartilage, irrespective of the effects of transducer orientation. To this end, ultrasound echoes were taken in the time domain from the articular surface and osteochondral junction of normal, collagen meshwork-disrupted, proteoglycan-depleted, and osteoarthritic samples, converted to the frequency domain by fast Fourier transform and analyzed. Our results show the significant effects of specific enzymatic degradation programs on the ultrasound frequency profile of reflections from the cartilage surface and osteochondral junction, and their manifestation in the tissue surrounding a focal osteoarthritic defect. Collagen meshwork disruption was most apparent in the profile of reflections from the articular surface, while proteoglycan depletion was most clearly observed in the reflections from the osteochondral junction. The reflected signals from the osteochondral junction may further contain information about the subchondral bone. From these results we proposed that the analysis of specific frequencies of reflected ultrasound signals has the potential to differentiate normal from degraded articular cartilage-on-bone, when the angle of incidence can be controlled within a ±1.2° limit. This encourages further research into the effects of progressive artificial degradation of the cartilage matrix and subchondral bone on the spectral profile to quantify the relationship between the frequency profile and the level of specific degradation in naturally degraded joints. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
12. Indentation stiffness does not discriminate between normal and degraded articular cartilage
- Author
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Brown, Cameron P., Crawford, Ross W., and Oloyede, Adekunle
- Subjects
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CARTILAGE , *ARTICULAR cartilage , *BIOMECHANICS , *ARTIFICIAL implants , *SURGERY - Abstract
Abstract: Background: Relative indentation characteristics are commonly used for distinguishing between normal healthy and degraded cartilage. The application of this parameter in surgical decision making and an appreciation of articular cartilage biomechanics has prompted us to hypothesise that it is difficult to define a reference stiffness to characterise normal articular cartilage. Methods: This hypothesis is tested for validity by carrying out biomechanical indentation of articular cartilage samples that are characterised as visually normal and degraded relative to proteoglycan depletion and collagen disruption. Compressive loading was applied at known strain rates to visually normal, artificially degraded and naturally osteoarthritic articular cartilage and observing the trends of their stress–strain and stiffness characteristics. Findings: While our results demonstrated a 25% depreciation in the stiffness of individual samples after proteoglycan depletion, they also showed that when compared to the stiffness of normal samples only 17% lie outside the range of the stress–strain behaviour of normal samples. Interpretation: We conclude that the extent of the variability in the properties of normal samples, and the degree of overlap (81%) of the biomechanical properties of normal and degraded matrices demonstrate that indentation data cannot form an accurate basis for distinguishing normal from abnormal articular cartilage samples with consequences for the application of this mechanical process in the clinical environment. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
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13. Potential enhancement of articular cartilage histological grading with collagen integrity.
- Author
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Moody, Hayley R., Afara, Isaac O., Singh, Sanjleena, and Oloyede, Adekunle
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ARTICULAR cartilage , *COLLAGEN , *HISTOLOGY , *RESEARCH - Abstract
Background Histological evaluation of articular cartilage, such as using the Mankin scoring system, is the gold standard for characterization of tissue integrity. This scoring system takes into account several parameters indicative of the tissue's health; however, the collagen integrity, which is a primary indicator of cartilage health is not taken into consideration. Thus, there is need to enhance histological grading of articular cartilage by incorporating explicit scoring of collagen degeneration into the Modified Mankin grading system. This paper explores a new histological grading parameter for collagen network degradation and how this information can be used to augment a widely used grading scheme like the Modified Mankin grading system. Methods Intact and degenerated human cartilage were examined histologically and then subjected to second harmonic generation imaging, leading to qualitative and quantitative description of collagen disruption emanating from the surface to subsurface layers of the tissue. This data was then incorporated into the Modified Mankin grading system. Findings Second harmonic generation image analysis reveals a relationship between changes in collagen architecture and histologically observed tissue disruption in degenerated articular cartilage. Interpretation Histological tissue disruption in degenerated human articular cartilage is directly related to the reorganization of collagen fibrils in the form of intense fibril aggregation, either as a result of degeneration or aging. This method of mapping disrupted tissue regions to quantitative collagen fibril damage can be coded into cartilage grading systems and could inform clinical practice and scientific research. [ABSTRACT FROM AUTHOR]
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- 2018
- Full Text
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14. The ultra-low friction of the articular surface is pH-dependent and is built on a hydrophobic underlay including a hypothesis on joint lubrication mechanism
- Author
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Pawlak, Zenon, Figaszewski, Zbigniew A., Gadomski, Adam, Urbaniak, Wieslaw, and Oloyede, Adekunle
- Subjects
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LUBRICATION & lubricants , *FRICTION , *PH effect , *ARTICULAR cartilage , *REVERSED micelles , *PHOSPHOLIPIDS , *ELECTROPHORESIS - Abstract
Abstract: In this study, the influence of pH on interfacial energy distributed over the phospholipids-bilayer surface model and the effect of hydrophobicity on coefficient of friction (f) were investigated by using microelectrophoresis. An important clinical implication of deficiency in hydrophobicity is the loss of phospholipids that is readily observed in osteoarthritis joints. This paper establishes the influence of pH on interfacial energy upon an increase f, which might be associated with a decrease of hydrophobicity of the articular surface. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
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