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Chittajallu SNSH, Gururani H, Jakati S, Basu S, Vaddavalli PK, Tse KM, Chinthapenta V. Investigation of mechanical strength and structure of corneal graft-host junction. Heliyon 2024; 10:e30871. [PMID: 38784531 PMCID: PMC11112333 DOI: 10.1016/j.heliyon.2024.e30871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Accepted: 05/07/2024] [Indexed: 05/25/2024] Open
Abstract
Dehiscence is a common complication of corneal transplant surgery involving separating the graft from the host eye. The present article aims to investigate fundamental insights into the mechanical and structural aspects of the graft-host junction (GHJ) of a graft that survived in a patient for 13 years after penetrating keratoplasty (PK). Additionally, it adopts the sutur retention strength (SRS) test procedure defined in ISO:7198-2016 and aims to provide a comprehensive test protocol to study the biomechanics of the GHJ in extracted PK buttons. A 9 mm corneal button with GHJ was extracted from a 46-year-old patient who underwent PK 13 years back. The strength of the GHJ was quantified using the SRS test. Corresponding control results were obtained from the SRS tests of a corneoscleral button with no history of any refractive procedure. Birefringence, histological, and scanning electron microscopy (SEM) imaging were used to visualize the microstructural details of the GHJ. The strength of the GHJ was observed to be ten times lower than the native cornea. Histopathological features, such as fragmented Bowman's layer, and fibrosis with a clear demarcation line between host and graft tissue, were observed at the GHJ, suggesting a weak bond across the GHJ. The low strength of the GHJ in PK indicates the high susceptibility of the GHJ towards wound dehiscence.
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Affiliation(s)
- Sai Naga Sri Harsha Chittajallu
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Hyderabad, India
- Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Melbourne, Australia
- Centre for Technology Innovation, L V Prasad Eye Institute, Hyderabad, India
| | - Himanshu Gururani
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Hyderabad, India
| | - Saumya Jakati
- Ophthalmic Pathology Laboratory, LV Prasad Eye Institute, Hyderabad, India
| | - Sayan Basu
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, LV Prasad Eye Institute, Hyderabad, India
| | | | - Kwong Ming Tse
- Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Melbourne, Australia
| | - Viswanath Chinthapenta
- Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Hyderabad, India
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Gururani H, Chittajallu SNSH, Doulatramani M, Manoharan R, Basu S, Chinthapenta V. Intraoperative collagen imaging of sutured cornea: A way towards managing post-penetrating keratoplasty astigmatism. Med Eng Phys 2024; 123:104076. [PMID: 38365329 DOI: 10.1016/j.medengphy.2023.104076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 11/28/2023] [Accepted: 12/03/2023] [Indexed: 02/18/2024]
Abstract
The birefringent nature of the human cornea plays an important role in comprehending its structural behavior in both diseased and surgical conditions. During corneal transplantation, irregular astigmatism is a common post-surgical complication that depends on the characteristics of suturing. Four human cadaver corneas are subjected to an in-vitro model of a typical full-thickness penetrating keratoplasty (PK) procedure using 16 simple interrupted 10-0 vicyrl sutures. The birefringence of these four corneas is analyzed using digital photoelasticity and compared with the control cornea (without PK). It is found that the sutures and their mutual interaction influence the morphology of the peripheral birefringence of the cornea. The findings of the present investigation are pertinent to intraoperative suture management during PK. Results suggest conserving the typical diamond-shaped morphology of peripheral birefringence would ensure uniform distribution of sutures. Therefore, birefringence imaging could be useful in suture management to ensure proper apposition of the graft-host junction, thus minimizing the risk of irregular astigmatism.
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Affiliation(s)
| | - Sai Naga Sri Harsha Chittajallu
- Micro-Mechanics Lab, IIT Hyderabad, Kandi, Sangareddy 502284, India; Prof. Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad 500034, India
| | | | - Ramji Manoharan
- Engineering Optics Lab, IIT Hyderabad, Kandi, Sangareddy 502284, India
| | - Sayan Basu
- Prof. Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad 500034, India; The Cornea Institute, LV Prasad Eye Institute, Hyderabad 500034, India
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Tinasi ALSN, Silveira CPB, Honsho CS, Laus JL, Aldrovani M. Birefringence analysis of collagen supraorganization in cat corneas with tropical keratopathy. Vet Ophthalmol 2023; 26:398-406. [PMID: 37335898 DOI: 10.1111/vop.13124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/02/2023] [Accepted: 06/10/2023] [Indexed: 06/21/2023]
Abstract
OBJECTIVE To evaluate the birefringent properties of the cornea and examine the supraorganizational aspects of collagen fibers in cats with tropical keratopathy. PROCEDURE In this study, 10-micrometer-thick sections of corneal tissue from cats with tropical keratopathy were examined, both in the opaque and transparent areas of the anterior stroma. Control samples were obtained from healthy cat corneas. Polarized light microscopy was employed to evaluate the birefringent properties using two distinct methods. The first method involved measuring the optical retardation associated with corneal birefringence, while the second method assessed the alignment/waviness of the birefringent collagen fibers. Differences were significant when p < .05. RESULTS Tropical keratopathy resulted in a significant rise (p < .05) in optical retardation in both opaque and transparent regions of the cat cornea. In the anterior stroma, both the opaque zones and transparent tissue exhibited a higher degree of collagen fiber packing than the control corneas. However, no significant differences (p > .05) in alignment were observed between the transparent tissue of the diseased cornea and the healthy corneas. CONCLUSION Supraorganizational changes in collagen fiber packing are not restricted to lesion zones in cat corneas affected by tropical keratopathy. Such alterations also occur in the corneal tissue of the anterior stroma adjoining the lesions. Therefore, it is plausible that the transparent tissue of the anterior stroma in corneas affected by the disease may have functional abnormalities, despite its macroscopic healthy appearance. Additional investigations are required to clarify the implications of these potential defects and their conceivable contribution to tropical keratopathy.
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Numerical Simulation of Corneal Fibril Reorientation in Response to External Loading. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16183278. [PMID: 31500114 PMCID: PMC6765893 DOI: 10.3390/ijerph16183278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/02/2019] [Accepted: 09/04/2019] [Indexed: 11/16/2022]
Abstract
Purpose: To simulate numerically the collagen fibril reorientation observed experimentally in the cornea. Methods: Fibril distribution in corneal strip specimens was monitored using X-ray scattering while under gradually increasing axial loading. The data were analysed at each strain level in order to quantify the changes in the angular distribution of fibrils with strain growth. The resulting relationship between stain and fibril reorientation was adopted in a constitutive model to control the mechanical anisotropy of the tissue material. The outcome of the model was validated against the experimental measurements before using the model in simplified representations of two surgical procedures. Results: The numerical model was able to reproduce the experimental measurements of specimen deformation and fibril reorientation under uniaxial loading with errors below 8.0%. With tissue removal simulated in a full eye numerical model, fibril reorientation could be predicted around the affected area, and this change both increased with larger tissue removal and reduced gradually away from that area. Conclusion: The presented method can successfully simulate fibril reorientation with changes in the strain regime affecting cornea tissue. Analyses based on this method showed that fibrils tend to align parallel to the tissue cut following keratoplasty operations. With the ability to simulate fibril reorientation, numerical modelling can have a greater potential in modelling the behaviour following surgery and injury to the cornea.
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Zhou D, Eliasy A, Abass A, Markov P, Whitford C, Boote C, Movchan A, Movchan N, Elsheikh A. Analysis of X-ray scattering microstructure data for implementation in numerical simulations of ocular biomechanical behaviour. PLoS One 2019; 14:e0214770. [PMID: 30934028 PMCID: PMC6443175 DOI: 10.1371/journal.pone.0214770] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/19/2019] [Indexed: 11/18/2022] Open
Abstract
This study aimed to analyse microstructure data on the density and orientation of collagen fibrils in whole eye globes and to propose an effective method for the preparation of data for use in numerical simulations of the eye’s biomechanical performance. Wide-angle X-ray scattering was applied to seven healthy ex-vivo human eyes. Each eye was dissected into an anterior and a posterior cup, and radial incisions were used to flatten the tissue before microstructure characterisation. A method was developed to use the microstructure data obtained for the dissected tissue to build realistic 3D maps of fibril density and orientation covering the whole eye globe. At the central cornea, 61.5±2.3% of fibrils were aligned within 45° sectors surrounding the two orthogonal directions. In contrast, more than one-third of the total fibril content was concentrated along the circumferential direction at the limbus (37.0±2.4%) and around the optic nerve head (34.8±2.1%). The insertion locations of the four recti muscles exhibited a preference in the meridional direction near the equator (38.6±3.9%). There was also a significant difference in fibril density between the limbus and other regions (ratio = 1.91±0.45, p <0.01 at the central cornea and ratio = 0.80±0.21, p <0.01 at the posterior pole). Characterisation of collagen fibril density and orientation across the whole ocular surface has been possible but required the use of a technique that involved tissue dissection and hence caused tissue damage. The method presented in this paper aimed to minimise the effect of dissection on the quality of obtained data and was successful in identifying fibril distribution trends that were compatible with earlier studies, which concentrated on localised areas of the ocular globe.
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Affiliation(s)
- Dong Zhou
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Petar Markov
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | | | - Craig Boote
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Alexander Movchan
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Natalia Movchan
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- National Institute for Health Research Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital National Health Service Foundation Trust and University College London Institute of Ophthalmology, London, United Kingdom
- School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China
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Biological and biomechanical analysis of two types of mesenchymal stem cells for intervention in chemotherapy-induced ovarian dysfunction. Arch Gynecol Obstet 2016; 295:247-252. [PMID: 27928675 DOI: 10.1007/s00404-016-4224-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 10/25/2016] [Indexed: 12/20/2022]
Abstract
PURPOSE The study aim was to investigate the biological and biomechanical features of a chemotherapy-induced ovarian dysfunction (CIOD) rat model after intervention with human umbilical cord mesenchymal stem cells (UC-MSCs) and human amniotic mesenchymal stem cells (h-AMSCs), thus providing a biological and biomechanical research basis for clinical treatment. METHODS The serum levels of estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and vascular endothelial growth factor (VEGF) in the rat CIOD models were evaluated on the 14th, 30th, 60th, and 90th day of intervention with h-AMSCs and UC-MSCs. In addition, the ovaries in each group were sampled on the 14th and 90th day of intervention for tissue morphology and tensile testing. RESULTS The serum levels of E2, LH, and VEGF in the h-AMSC and UC-MSC groups were greater than in the model group, but the serum FSH level was less than in the model group, and the differences were significant (P < 0.05); the maximum tensile stress and maximum strain in h-AMSC and UC-MSC groups were significantly greater than in the model group (P < 0.05). CONCLUSIONS UC-MSC and h-AMSC intervention restored damaged ovarian morphology, elasticity, and toughness to a certain extent, and ovarian function showed some recovery.
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Sigal IA, Steele J, Drexler S, Lathrop KL. Identifying the Palisades of Vogt in Human Ex Vivo Tissue. Ocul Surf 2016; 14:435-439. [PMID: 27520448 PMCID: PMC5155510 DOI: 10.1016/j.jtos.2016.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/22/2016] [Indexed: 11/25/2022]
Abstract
PURPOSE The Palisades of Vogt (POV) constitute the corneal epithelial stem cell niche, but identification of this region in ex vivo tissue is difficult. Here we introduce a simple, direct method of identifying the POV in unsectioned, ex vivo human tissue. METHODS Twenty-two eyes were studied, four whole and eighteen rims. Orientation of whole eyes was determined and the eyes were marked to maintain their cardinal orientation prior to dissection. Samples were imaged with brightfield, linearly polarized light and transmitted circularly polarized light (CPL), and optical coherence tomography (OCT) volumes were acquired in all twelve clock hrs around the limbus. Five samples were also fluorescently labeled to identify the epithelial basement membrane, and whole mounts were imaged with laser scanning confocal microscopy. Images were compared to confirm that the structures visible with polarized light were POV. RESULTS Under CPL the POV presented as amber radial ridges visible in the superior and inferior regions of the tissue. Identification of POV was confirmed by correlating the structures seen under CPL, OCT and laser-scanning confocal microscopy. CONCLUSIONS CPL can be used to quickly identify POV regions in donor tissue. This technique can assist in targeted harvesting of stem cell regions for research and tissue for limbal transplant.
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Affiliation(s)
- Ian A Sigal
- University of Pittsburgh School of Medicine, Department of Ophthalmology, Pittsburgh, Pennsylvania, USA; University of Pittsburgh Swanson School of Engineering, Department of Bioengineering, Pittsburgh, Pennsylvania, USA
| | - Jessica Steele
- University of Pittsburgh School of Medicine, Department of Ophthalmology, Pittsburgh, Pennsylvania, USA
| | - Scott Drexler
- University of Pittsburgh School of Medicine, Department of Ophthalmology, Pittsburgh, Pennsylvania, USA
| | - Kira L Lathrop
- University of Pittsburgh School of Medicine, Department of Ophthalmology, Pittsburgh, Pennsylvania, USA; University of Pittsburgh Swanson School of Engineering, Department of Bioengineering, Pittsburgh, Pennsylvania, USA.
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Sibillano T, De Caro L, Scattarella F, Scarcelli G, Siliqi D, Altamura D, Liebi M, Ladisa M, Bunk O, Giannini C. Interfibrillar packing of bovine cornea by table-top and synchrotron scanning SAXS microscopy. J Appl Crystallogr 2016; 49:1231-1239. [PMID: 27504077 PMCID: PMC4970496 DOI: 10.1107/s1600576716010396] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/27/2016] [Indexed: 11/10/2022] Open
Abstract
Bovine cornea was studied with scanning small-angle X-ray scattering (SAXS) microscopy, by using both synchrotron radiation and a microfocus laboratory source. A combination of statistical (adaptive binning and canonical correlation analysis) and crystallographic (pair distribution function analysis) approaches allowed inspection of the collagen lateral packing of the supramolecular structure. Results reveal (i) a decrease of the interfibrillar distance and of the shell thickness around the fibrils from the periphery to the center of the cornea, (ii) a uniform fibril diameter across the explored area, and (iii) a distorted quasi-hexagonal arrangement of the collagen fibrils. The results are in agreement with existing literature. The overlap between laboratory and synchrotron-radiation data opens new perspectives for further studies on collagen-based/engineered tissues by the SAXS microscopy technique at laboratory-scale facilities.
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Affiliation(s)
- T. Sibillano
- Istituto di Cristallografia (IC-CNR), via Amendola 122/O, Bari, I-70126, Italy
| | - L. De Caro
- Istituto di Cristallografia (IC-CNR), via Amendola 122/O, Bari, I-70126, Italy
| | - F. Scattarella
- IOM CNR Laboratorio TASC, Area Science Park – Basovizza, Bld MM SS 14, Trieste, 34149, Italy
| | - G. Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - D. Siliqi
- Istituto di Cristallografia (IC-CNR), via Amendola 122/O, Bari, I-70126, Italy
| | - D. Altamura
- Istituto di Cristallografia (IC-CNR), via Amendola 122/O, Bari, I-70126, Italy
| | - M. Liebi
- Paul Scherrer Institut, Swiss Light Source, 5232, Villigen PSI, Switzerland
| | - M. Ladisa
- Istituto di Cristallografia (IC-CNR), via Amendola 122/O, Bari, I-70126, Italy
| | - O. Bunk
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - C. Giannini
- Istituto di Cristallografia (IC-CNR), via Amendola 122/O, Bari, I-70126, Italy
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Bao F, Geraghty B, Wang Q, Elsheikh A. Consideration of corneal biomechanics in the diagnosis and management of keratoconus: is it important? EYE AND VISION 2016; 3:18. [PMID: 27382596 PMCID: PMC4932704 DOI: 10.1186/s40662-016-0048-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 06/13/2016] [Indexed: 11/10/2022]
Abstract
Keratoconus is a bilateral, non-inflammatory, degenerative corneal disease. The occurrence and development of keratoconus is associated with corneal thinning and conical protrusion, which causes irregular astigmatism. With the disruption of the collagen organization, the cornea loses its shape and function resulting in progressive visual degradation. Currently, corneal topography is the most important tool for the diagnosis of keratoconus, which may lead to false negatives among the patient population in the subclinical phase. However, it is now hypothesised that biomechanical destabilisation of the cornea may take place ahead of the topographic evidence of keratoconus, hence possibly assisting with disease diagnosis and management. This article provides a review of the definition, diagnosis, and management strategies for keratoconus based on corneal biomechanics.
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Affiliation(s)
- FangJun Bao
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou City, 325027 China ; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou City, 325027 China
| | - Brendan Geraghty
- School of Engineering, University of Liverpool, Liverpool City, L69 3GH UK
| | - QinMei Wang
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou City, 325027 China ; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou City, 325027 China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool City, L69 3GH UK ; NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London City, UK
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Pessoa WS, Estevão LRDM, Simões RS, Mendonça FDS, Evêncio-Luz L, Baratella-Evêncio L, Florencio-Silva R, Sá FBD, Evêncio-Neto J. Fibrogenesis and epithelial coating of skin wounds in rats treated with angico extract (Anadenanthera colubrina var. cebil). Acta Cir Bras 2015; 30:353-8. [PMID: 26016935 DOI: 10.1590/s0102-865020150050000007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/18/2015] [Indexed: 11/21/2022] Open
Abstract
PURPOSE To evaluate the effects of angico bark extract (Anadenanthera colubrina var. cebil) in the healing process of the skin of rats. METHODS Twenty adult male rats were divided into four groups of five animals each, according to the respective postoperative days, as follow: G4, G7, G14 and G21. Each group received two incisions on skin and subcutaneous tissue in the right and left antimere of the thoracic region, separated by a distance of 2 cm. The right lesion was treated daily with saline and the left with the angico alcoholic extract (5%). At the end of each experimental period, the animals were euthanized and fragments of the wound area with the edges were removed, fixed in 10% formaldehyde solution and processed for paraffin embedding. Histological sections (5 μm of thickness) were stained with hematoxylin and eosin (HE), Gomori trichromic and picrosisirus red for morphological and morphometric analyses. Statistical analysis was done by ANOVA and Tukey-Kramer test (p<0.05). RESULTS Morphological analysis showed larger fibroblasts and a higher concentration of collagen fibers in skyn wounds treated with the angico extract. Morphometric analysis demonstrated a significant increase in the number of fibroblasts at 7th and collagen in 7th and 14th days (p<0.01) in wounds treated with the angico extract. CONCLUSION The angico alcoholic extract (Anadenanthera colubrina var. cebil) induces the acceleration of wound healing in skin wounds of rats.
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Meek KM, Knupp C. Corneal structure and transparency. Prog Retin Eye Res 2015; 49:1-16. [PMID: 26145225 PMCID: PMC4655862 DOI: 10.1016/j.preteyeres.2015.07.001] [Citation(s) in RCA: 438] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/28/2015] [Accepted: 07/01/2015] [Indexed: 12/13/2022]
Abstract
The corneal stroma plays several pivotal roles within the eye. Optically, it is the main refracting lens and thus has to combine almost perfect transmission of visible light with precise shape, in order to focus incoming light. Furthermore, mechanically it has to be extremely tough to protect the inner contents of the eye. These functions are governed by its structure at all hierarchical levels. The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought and that the intricacy of the arrangement of the collagenous lamellae provides the shape and the mechanical properties of the tissue. At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure. In this review we describe the current state of knowledge about the three-dimensional stromal architecture at the microscopic level, and about the control mechanisms at the nanoscopic level that lead to optical transparency.
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Affiliation(s)
- Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
| | - Carlo Knupp
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK
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