WorldWideScience

Sample records for native-like collagen fiber

  1. Recombinant Minimalist Spider Wrapping Silk Proteins Capable of Native-Like Fiber Formation

    Science.gov (United States)

    Xu, Lingling; Rainey, Jan K.; Meng, Qing; Liu, Xiang-Qin

    2012-01-01

    Spider silks are desirable biomaterials characterized by high tensile strength, elasticity, and biocompatibility. Spiders produce different types of silks for different uses, although dragline silks have been the predominant focus of previous studies. Spider wrapping silk, made of the aciniform protein (AcSp1), has high toughness because of its combination of high elasticity and tensile strength. AcSp1 in Argiope trifasciata contains a 200-aa sequence motif that is repeated at least 14 times. Here, we produced in E. coli recombinant proteins consisting of only one to four of the 200-aa AcSp1 repeats, designated W1 to W4. We observed that purified W2, W3 and W4 proteins could be induced to form silk-like fibers by shear forces in a physiological buffer. The fibers formed by W4 were ∼3.4 µm in diameter and up to 10 cm long. They showed an average tensile strength of 115 MPa, elasticity of 37%, and toughness of 34 J cm−3. The smaller W2 protein formed fewer fibers and required a higher protein concentration to form fibers, whereas the smallest W1 protein did not form silk-like fibers, indicating that a minimum of two of the 200-aa repeats was required for fiber formation. Microscopic examinations revealed structural features indicating an assembly of the proteins into spherical structures, fibrils, and silk-like fibers. CD and Raman spectral analysis of protein secondary structures suggested a transition from predominantly α-helical in solution to increasingly β-sheet in fibers. PMID:23209681

  2. Recombinant minimalist spider wrapping silk proteins capable of native-like fiber formation.

    Directory of Open Access Journals (Sweden)

    Lingling Xu

    Full Text Available Spider silks are desirable biomaterials characterized by high tensile strength, elasticity, and biocompatibility. Spiders produce different types of silks for different uses, although dragline silks have been the predominant focus of previous studies. Spider wrapping silk, made of the aciniform protein (AcSp1, has high toughness because of its combination of high elasticity and tensile strength. AcSp1 in Argiope trifasciata contains a 200-aa sequence motif that is repeated at least 14 times. Here, we produced in E. coli recombinant proteins consisting of only one to four of the 200-aa AcSp1 repeats, designated W(1 to W(4. We observed that purified W(2, W(3 and W(4 proteins could be induced to form silk-like fibers by shear forces in a physiological buffer. The fibers formed by W(4 were ∼3.4 µm in diameter and up to 10 cm long. They showed an average tensile strength of 115 MPa, elasticity of 37%, and toughness of 34 J cm(-3. The smaller W(2 protein formed fewer fibers and required a higher protein concentration to form fibers, whereas the smallest W(1 protein did not form silk-like fibers, indicating that a minimum of two of the 200-aa repeats was required for fiber formation. Microscopic examinations revealed structural features indicating an assembly of the proteins into spherical structures, fibrils, and silk-like fibers. CD and Raman spectral analysis of protein secondary structures suggested a transition from predominantly α-helical in solution to increasingly β-sheet in fibers.

  3. Oriented collagen fibers direct tumor cell intravasation

    KAUST Repository

    Han, Weijing

    2016-09-24

    In this work, we constructed a Collagen I-Matrigel composite extracellular matrix (ECM). The composite ECM was used to determine the influence of the local collagen fiber orientation on the collective intravasation ability of tumor cells. We found that the local fiber alignment enhanced cell-ECM interactions. Specifically, metastatic MDA-MB-231 breast cancer cells followed the local fiber alignment direction during the intravasation into rigid Matrigel (∼10 mg/mL protein concentration).

  4. Elastic fibers and collagen distribution in human aorta

    Science.gov (United States)

    Vieira-Damiani, G.; Ferro, D. P.; Adam, R. L.; de Thomaz, A. A.; Pelegati, V.; Cesar, C. L.; Metze, K.

    2011-03-01

    Elastic and collagen fibers are essential components of the aorta, the remodeling of these structures is accompanied with aging in various diseases and life-threatening events. While the elastic fibers confer resilience to major blood vessels collagen confers resistance to the same. Elastic fibers are easily visualized in the fluorescent light when stained with hematoxylin eosin. Second Harmonic Generation (SHG) is a non linear signal that occurs only in molecules without inversion symmetry and is particularly strong in the collagen fibers arranged in triple helices. The aim of this paper is to describe the distribution of collagen in the thickness of the thoracic aorta, and to demonstrate the distribution of between elastic fibers. The images were acquired in a multifoton microscopy and both signals, Two-phtoton excitaded fluorescence (TPEF) and SHG, were excited by a Ti:Sapphire laser. We used a band pass filter to filter the SHG signal from the TPEF signal. The thickness of the aorta varies 2-3 mm, and the image was composed of the juxtaposition of images of 220 x 220 microns. We acquired images of a histological slide of the thoracic aorta stained with picrosirius red (specific for collagen) at a wavelength of 670nm SHG subsequently acquired images with the same region and observed that the images are overlapping. Therefore, the following images were acquired by confocal microscopy (fluorescence of eosin for visualization of elastic fibers) and for collagen SHG. After reconstruction of the images, we observed the distribution of collagen along the aorta.

  5. APPLICATION OF THE COLLAGENOUS FIBER FROM THE SOLID WASTES OF LEATHER FOR PAPERMAKING

    Institute of Scientific and Technical Information of China (English)

    Zhijie Wang; Jian Wang; Zhang Chuanbo; Hou Xiaodong

    2004-01-01

    The capability of pulping for the solid waste of leather was investigated. The properties of paper that made up of collagenous fiber and plant fiber were also analyzed. The result showed that by proper treatment, solid waste of leather could be made into collagen fiber for papermaking. The physical strength of paper can be enhanced by appending collagenous fiber in a proper propriety.

  6. Role of collagen fibers in acupuncture analgesia therapy on rats.

    Science.gov (United States)

    Yu, Xiaojia; Ding, Guanghong; Huang, Hong; Lin, Jun; Yao, Wei; Zhan, Rui

    2009-01-01

    Acupuncture, a traditional Chinese therapeutic technique, has been put into practice for more than 4000 years and widely used for pain management since 1958. However, what is the mechanism underlying the acupuncture for analgesia effects by stimulation of acupoints, what substances receive the original mechanical acupuncture signals from the acupoints, or what transforms these signals into effective biological signals are not well understood. In this work, the role of collagen fibers at acupoints during acupuncture analgesia on rats was investigated. When the structure of the collagen fibers at Zusanli (ST36) was destroyed by injection of type I collagenase, the needle force caused by the acupuncture declined and the analgesic effects of rotation or lift-thrusting manipulations was attenuated accompanying the restraint of the degranulation ratios of mast cells. We propose that collagen fibers play an important role in acupuncture-induced analgesia, and they participate in signal transmission and transform processes.

  7. Computational analysis of light scattering from collagen fiber networks

    Science.gov (United States)

    Arifler, Dizem; Pavlova, Ina; Gillenwater, Ann; Richards-Kortum, Rebecca

    2007-07-01

    Neoplastic progression in epithelial tissues is accompanied by structural and morphological changes in the stromal collagen matrix. We used the Finite-Difference Time-Domain (FDTD) method, a popular computational technique for full-vector solution of complex problems in electromagnetics, to establish a relationship between structural properties of collagen fiber networks and light scattering, and to analyze how neoplastic changes alter stromal scattering properties. To create realistic collagen network models, we acquired optical sections from the stroma of fresh normal and neoplastic oral cavity biopsies using fluorescence confocal microscopy. These optical sections were then processed to construct three-dimensional collagen networks of different sizes as FDTD model input. Image analysis revealed that volume fraction of collagen fibers in the stroma decreases with neoplastic progression, and statistical texture features computed suggest that fibers tend to be more disconnected in neoplastic stroma. The FDTD modeling results showed that neoplastic fiber networks have smaller scattering cross-sections compared to normal networks of the same size, whereas high-angle scattering probabilities tend to be higher for neoplastic networks. Characterization of stromal scattering is expected to provide a basis to better interpret spectroscopic optical signals and to develop more reliable computational models to describe photon propagation in epithelial tissues.

  8. Dynamics of Cancer Cell near Collagen Fiber Chain

    Science.gov (United States)

    Kim, Jihan; Sun, Bo

    Cell migration is an integrated process that is important in life. Migration is essential for embryonic development as well as homeostatic processes such as wound healing and immune responses. When cell migrates through connective extracellular matrix (ECM), it applies cellular traction force to ECM and senses the rigidity of their local environment. We used human breast cancer cell (MDA-MB-231) which is highly invasive and applies strong traction force to ECM. As cancer cell applies traction force to type I collage-based ECM, it deforms collagen fibers near the surface. Patterns of deforming collagen fibers are significantly different with pairs of cancer cells compared to a single cancer cell. While a pair of cancer cells within 60 um creates aligned collagen fiber chains between them permanently, a single cancer cell does not form any fiber chains. In this experiment we measured a cellular response and an interaction between a pair of cells through the chain. Finally, we analyzed correlation of directions between cancer cell migration and the collagen chain alignment.

  9. Elastic and viscoelastic properties of a type I collagen fiber.

    Science.gov (United States)

    Sopakayang, Ratchada; De Vita, Raffaella; Kwansa, Albert; Freeman, Joseph W

    2012-01-21

    A new mathematical model is presented to describe the elastic and viscoelastic properties of a single collagen fiber. The model is formulated by accounting for the mechanical contribution of the collagen fiber's main constituents: the microfibrils, the interfibrillar matrix and crosslinks. The collagen fiber is modeled as a linear elastic spring, which represents the mechanical contribution of the microfibrils, and an arrangement in parallel of elastic springs and viscous dashpots, which represent the mechanical contributions of the crosslinks and interfibrillar matrix, respectively. The linear elastic spring and the arrangement in parallel of elastic springs and viscous dashpots are then connected in series. The crosslinks are assumed to gradually break under strain and, consequently, the interfibrillar is assumed to change its viscous properties. Incremental stress relaxation tests are conducted on dry collagen fibers reconstituted from rat tail tendons to determine their elastic and viscoelastic properties. The elastic and total stress-strain curves and the stress relaxation at different levels of strain collected by performing these tests are then used to estimate the parameters of the model and evaluate its predictive capabilities.

  10. Morphology of collagen fibers and elastic system fibers in actinic cheilitis

    Directory of Open Access Journals (Sweden)

    Sgarbi Flavia

    2010-01-01

    Full Text Available Background: Actinic cheilitis (AC is a premalignant condition intimately related to exposure of the lips to sun rays. Aim: The objective of this study was to evaluate the elastic and collagen fibers in the lamina propria of AC. The degree of epithelial atypia was correlated with the quantity of elastic and collagen fibers. Materials and Methods: Fifty-one cases were investigated. One slide was stained with hematoxylin-eosin for the evaluation of atypia, the second was stained with Weigert′s resorcin-fuchsin for the assessment of elastic fibers, and the third slide was stained with Mallory′s trichrome for the analysis of collagen fibers. Results: Ordinal logistic regression analysis revealed a significant correlation between the presence of atypia and collagen fibers (P<0.05. Conclusions: It was concluded that there seems to be a reduction in the quantity of collagen fibers in cases of moderate and severe atypia. No correlation was observed between the degradation of elastic system fibers and the grade of dysplasia.

  11. The Importance of Collagen Fibers in Vertebrate Biology

    OpenAIRE

    Frederick H. Silver, Ph.D.

    2009-01-01

    Collagen fibers form the basic structural components of extracellular matrix (ECM) of vertebrates that serve to: (1) store elastic energy during muscular deformation, (2) transmit stored energy into joint movement, and (3) transfer excess energy from the joint back to the attached muscles for dissipation. They also act as mechanotransducers by transferring stress borne by the musculoskeleton to the attached cells in order to either up - or down - regulate tissue metabolism as a result of chan...

  12. Measurement of Elastic Modulus of Collagen Type I Single Fiber.

    Science.gov (United States)

    Dutov, Pavel; Antipova, Olga; Varma, Sameer; Orgel, Joseph P R O; Schieber, Jay D

    2016-01-01

    Collagen fibers are the main components of the extra cellular matrix and the primary contributors to the mechanical properties of tissues. Here we report a novel approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. This approach also avoids drying for measurements or visualization, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. The longitudinal component of the single-fiber elastic modulus is between 100 MPa and 360 MPa for samples extracted from different rats and/or different parts of a single tail. Variations are also observed in the fibril-bundle/fibril diameter with an average of 325±40 nm. Since bending forces depend on the diameter to the fourth power, this variation in diameter is important for estimating the range of elastic moduli. The remaining variations in the modulus may be due to differences in composition of the fibril-bundles, or the extent of the proteoglycans constituting fibril-bundles, or that some single fibrils may be of fibril-bundle size.

  13. Measurement of Elastic Modulus of Collagen Type I Single Fiber.

    Directory of Open Access Journals (Sweden)

    Pavel Dutov

    Full Text Available Collagen fibers are the main components of the extra cellular matrix and the primary contributors to the mechanical properties of tissues. Here we report a novel approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. This approach also avoids drying for measurements or visualization, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. The longitudinal component of the single-fiber elastic modulus is between 100 MPa and 360 MPa for samples extracted from different rats and/or different parts of a single tail. Variations are also observed in the fibril-bundle/fibril diameter with an average of 325±40 nm. Since bending forces depend on the diameter to the fourth power, this variation in diameter is important for estimating the range of elastic moduli. The remaining variations in the modulus may be due to differences in composition of the fibril-bundles, or the extent of the proteoglycans constituting fibril-bundles, or that some single fibrils may be of fibril-bundle size.

  14. Effect of CNT on collagen fiber structure, stiffness assembly kinetics and stem cell differentiation.

    Science.gov (United States)

    Kim, Taeyoung; Sridharan, Indumathi; Zhu, Bofan; Orgel, Joseph; Wang, Rong

    2015-04-01

    Collagen is a native one-dimensional nanomaterial. Carbon nanotube (CNT) was found to interface with biological materials and show promising applications in creating reinforced scaffolds for tissue engineering and regenerative medicine. In this study, we examined the unique role of CNT in collagen fiber structure, mechanical strength and assembly kinetics. The results imply that CNT interacts with collagen at the molecular level. It relaxes the helical coil of collagen fibrils and has the effect of flattening the fibers leading to the elongation of D-period, the characteristic banding feature of collagen fibers. The surface charge of oxidized CNT leads to enhanced local ionic strength during collagen fibrillogenesis, accounting for the slower kinetics of collagen-CNT (COL-CNT) fiber assembly and the formation of thicker fibers. Due to the rigidity of CNT, the addition of CNT increases the fiber stiffness significantly. When applied as a matrix for human decidua parietalis placental stem cells (hdpPSCs) differentiation, COL-CNT was found to support fast and efficient neural differentiation ascribed to the elongated D-period. These results highlight the superiority of CNT to modulate collagen fiber assembly at the molecular level. The study also exemplifies the use of CNT to enhance the functionality of collagen for biological and biomedical applications.

  15. Collagen fiber angle in the submucosa of small intestine and its application in gastroenterology

    Institute of Scientific and Technical Information of China (English)

    Yan-Jun Zeng; Ai-Ke Qiao; Ji-Dong Yu; Jing-Bo Zhao; Dong-Hua Liao; Xiao-Hu Xu; Gregersen Hans

    2003-01-01

    AIM: To propose a simple and effective method suitable for analyzing the angle and distribution of 2-dimensional collagen fiber in larger sample of small intestine and to investigate the relationship between the angles of collagen fiber and the pressure it undergoes.METHODS: A kind of 2-dimensional visible quantitative analyzing technique was described. Digital image-processing method was utilized to determine the angle of collagen fiber in parenchyma according to the changes of area analyzed and further to investigate quantitatively the distribution of collagen fiber. A series of intestinal slice′s images preprocessed by polarized light were obtained with electron microscope,and they were processed to unify each pixel. The approximate angles between collagen fibers were obtained via analyzing the images and their corresponding polarized light. The relationship between the angles of collagen fiber and the pressure it undergoes were statistically summarized.RESULTS: The angle of collagen fiber in intestinal tissue was obtained with the quantitative analyzing method of calculating the ratio of different pixels. For the same slice,with polarized light angle′s variation, the corresponding ratio of different pixels was also changed; for slices under different pressures, the biggest ratio of collagen fiber area was changed either.CONCLUSION: This study suggests that the application of stress on the intestinal tissue will change the angle and content of collagen fiber. The method of calculating ratios of different pixel values to estimate collagen fiber angle was practical and reliable. The quantitative analysis used in the present study allows a larger area of soft tissue to be analyzed with relatively low cost and simple equipment.

  16. Effect of fiber crosslinking on collagen-fiber reinforced collagen-chondroitin-6-sulfate materials for regenerating load-bearing soft tissues.

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    Shepherd, J H; Ghose, S; Kew, S J; Moavenian, A; Best, S M; Cameron, R E

    2013-01-01

    Porous collagen-glycosaminoglycan structures are bioactive and exhibit a pore architecture favorable for both cellular infiltration and attachment; however, their inferior mechanical properties limit use, particularly in load-bearing situations. Reinforcement with collagen fibers may be a feasible route for enhancing the mechanical characteristics of these materials, providing potential for composites used for the repair and regeneration of soft tissue such as tendon, ligaments, and cartilage. Therefore, this study investigates the reinforcement of collagen-chondroitin-6-sulfate (C6S) porous structures with bundles of extruded, reconstituted type I collagen fibers. Fiber bundles were produced through extrusion and then, where applicable, crosslinked using a solution of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide. Fibers were then submerged in the collagen-C6S matrix slurry before being lyophilized. A second 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide crosslinking process was then applied to the composite material before a secondary lyophilization cycle. Where bundles had been previously crosslinked, composites withstood a load of approximately 60 N before failure, the reinforcing fibers remained dense and a favorable matrix pore structure resulted, with good interaction between fiber and matrix. Fibers that had not been crosslinked before lyophilization showed significant internal porosity and a channel existed between them and the matrix. Mechanical properties were significantly reduced, but the additional porosity could prove favorable for cell migration and has potential for directing aligned tissue growth.

  17. Nanometer-scale optical imaging of collagen fibers using gold nanoparticles.

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    Chen, Bo; Estrada, Laura C; Hellriegel, Christian; Gratton, Enrico

    2011-02-07

    We describe 3D single particle tracking of gold nanoparticles (AuNPs) moving along collagen fibers in aqueous environment with two-photon excitation conditions. The photoacoustic effect at the collagen fiber caused by the irradiation with ultrashort, near-infrared laser pulses propels the particles adsorbed to the surface of the collagen fibers. We report the tracking of individual AuNPs in three dimensions with high spatial and temporal resolution, of few nanometers and milliseconds, respectively. Due to the emission signal caused by the interaction between the AuNPs and the weak chromophores in the collagen fiber, the trajectories of individual AuNPs reveal the fiber topography with nanometric resolution. The intensity along the trajectory shows that we are sensitive to the distribution of the weak chromophores on the fiber.

  18. APPLICATION OF THE COLLAGENOUS FIBER FROM THE SOLID WASTES OF LEATHER FOR PAPERMAKING

    Institute of Scientific and Technical Information of China (English)

    ZhijieWang; JianWang; ZhangChuanbo; HouXiaodong

    2004-01-01

    The capability of pulping for the solid waste ofleather was investigated. The properties of paper thatmade up of collagenous fiber and plant fiber werealso analyzed. The result showed that by propertreatment, solid waste of leather could be made intocollagen fiber for papermaking. The physical strengthof paper can be enhanced by appending collagenousfiber in a proper propriety.

  19. Remodeling of the collagen fiber architecture due to compaction in small vessels under tissue engineered conditions.

    Science.gov (United States)

    Soares, Ana L F; Stekelenburg, Maria; Baaijens, Frank P T

    2011-07-01

    Mechanical loading protocols in tissue engineering (TE) aim to improve the deposition of a properly organized collagen fiber network. In addition to collagen remodeling, these conditioning protocols can result in tissue compaction. Tissue compaction is beneficial to tissue collagen alignment, yet it may lead to a loss of functionality of the TE construct due to changes in geometry after culture. Here, a mathematical model is presented to relate the changes in collagen architecture to the local compaction within a TE small blood vessel, assuming that under static conditions, compaction is the main factor responsible for collagen fiber organization. An existing structurally based model is extended to incorporate volumetric tissue compaction. Subsequently, the model is applied to describe the collagen architecture of TE constructs under either strain based or stress based stimulus functions. Our computations indicate that stress based simulations result in a helical collagen fiber distribution along the vessel wall. The helix pitch angle increases from a circumferential direction in the inner wall, over about 45 deg in the middle vessel layer, to a longitudinal direction in the outer wall. These results are consistent with experimental data from TE small diameter blood vessels. In addition, our results suggest a stress dependent remodeling of the collagen, suggesting that cell traction is responsible for collagen orientation. These findings may be of value to design improved mechanical conditioning protocols to optimize the collagen architecture in engineered tissues.

  20. In vivo visualization of dermal collagen fiber in skin burn by collagen-sensitive second-harmonic-generation microscopy

    Science.gov (United States)

    Tanaka, Ryosuke; Fukushima, Shu-ichiro; Sasaki, Kunihiko; Tanaka, Yuji; Murota, Hiroyuki; Matsumoto, Takeshi; Araki, Tsutomu; Yasui, Takeshi

    2013-06-01

    Optical assessment of skin burns is possible with second-harmonic-generation (SHG) microscopy due to its high sensitivity to thermal denaturation of collagen molecules. In contrast to previous studies that were performed using excised tissue specimens ex vivo, in vivo observation of dermal collagen fibers in living rat burn models with SHG microscopy is demonstrated. Changes in signal vanishing patterns in the SHG images are confirmed to be dependent on the burn degree. Comparison of the SHG images with Masson's trichrome-stained images indicated that the observed patterns were caused by the coexistence of molten and fibrous structures of dermal collagen fibers. Furthermore, a quantitative parameter for burn assessment based on the depth profile of the mean SHG intensity across the entire SHG image is proposed. These results and discussions imply a potential of SHG microscopy as a minimally invasive, highly quantitative tool for skin burn assessment.

  1. Tendon Creep Is Potentiated by NKISK and Relaxin Which Produce Collagen Fiber Sliding

    OpenAIRE

    Wood, Mark L; Luthin, William N; Lester, Gayle E; Dahners, Laurence E

    2003-01-01

    The pentapeptide NKISK has been reported to inhibit the binding of decorin, a proteoglycan on the surface of collagen fibrils, to fibronectin, a tissue adhesion molecule. Relaxin has been shown to be effective in relaxing ligaments and other connective tissues. Through collagen staining studies, we have previously demonstrated that collagen fiber sliding is important during changes in ligament length. Because of our interest in fibril-fibril binding as it relates to changes in length of tendo...

  2. Cells that emerge from embryonic explants produce fibers of type IV collagen.

    Science.gov (United States)

    Chen, J M; Little, C D

    1985-10-01

    Double immunofluorescence staining experiments designed to examine the synthesis and deposition of collagen types I and IV in cultured explants of embryonic mouse lung revealed the presence of connective tissue-like fibers that were immunoreactive with anti-type IV collagen antibodies. This observation is contrary to the widely accepted belief that type IV collagen is found only in sheet-like arrangements beneath epithelia or as a sheath-like layer enveloping bundles of nerve or muscle cells. The extracellular matrix produced by cells that migrate from embryonic mouse lung rudiments in vitro was examined by double indirect immunofluorescence microscopy. Affinity-purified monospecific polyclonal antibodies were used to examine cells after growth on glass or native collagen substrata. The data show that embryonic mesenchymal cells can produce organized fibers of type IV collagen that are not contained within a basement membrane, and that embryonic epithelial cells deposit fibers and strands of type IV collagen beneath their basal surface when grown on glass; however, when grown on a rat tail collagen substratum the epithelial cells produce a fine meshwork. To our knowledge this work represents the first report that type IV collagen can be organized by cells into a fibrous extracellular matrix that is not a basement membrane.

  3. Far-infrared spectroscopy of salt penetration into a collagen fiber scaffold.

    Science.gov (United States)

    Mizuno, Maya; Yamada, Akira; Fukunaga, Kaori; Kojima, Hiroaki

    2015-06-01

    We employed far-infrared spectroscopy to observe the amount of salt that penetrates into collagen fiber masses. The absorption properties of collagen sheets prepared from tilapia skin, bovine skin, rat tail, and sea cucumber dermis were measured using a transmission Fourier transform spectrometer in a band from approximately 100 to 700 cm(-1). We confirmed that the absorbance spectra of the four types of dried collagen sheet show good agreement, even though the amino acid compositions differed. The absorbance peaks observed in the band corresponded to collective vibrations of plural functional groups such as methylene and imino groups in collagen. When salt solution was added to the collagen sheets and then dried, the spectral shapes of the sheets at approximately 166 cm(-1) were clearly different from those of the plain collagen sheets. The differential absorbance between wavenumbers 166 cm(-1) and 250 cm(-1) sensitively reflected the difference between higher-order structures, and the salt diffusion (crystallization) depended on the collagen fiber condition. From these results, we consider that spectral changes can be used for the numerical evaluation of salt penetration into a collagen fiber scaffold.

  4. Contribution of collagen and elastin fibers to the mechanical behavior of an abdominal connective tissue.

    Science.gov (United States)

    Levillain, A; Orhant, M; Turquier, F; Hoc, T

    2016-08-01

    The linea alba is a complex structure commonly involved in hernia formation. Knowledge of its mechanical behavior is essential to design suitable meshes and reduce the risk of recurrence. The aim of this study was to investigate the relationships between the mechanical properties of the linea alba and the organization of collagen and elastin fibers. For that purpose, longitudinal and transversal samples were removed from four porcine and three human linea alba, to perform tensile tests under a biphotonic confocal microscope, in each direction. Microscopic observation revealed a tissue composed of two layers, made of transversal collagen fibers in the dorsal side and oblique collagen fibers in the ventral side. This particular architecture led to an anisotropic mechanical behavior, with higher stress in the transversal direction. During loading, oblique fibers of the ventral layer reoriented toward the tensile axis in both directions, while fibers of the dorsal layer remained in the transversal direction. This rotation of oblique fibers progressively increased the stiffness of the tissue and induced a non-linear stress-stretch relation. Elastin fibers formed a layer covering the collagen fibers and followed their movement, suggesting that they ensure their elastic recoil. All of these results demonstrated the strong relationships between the microstructure and the mechanical behavior of the linea alba.

  5. Analysis of mineral deposition in turkey tendons and self-assembled collagen fibers using mechanical techniques.

    Science.gov (United States)

    Freeman, Joseph W; Silver, Frederick H

    2004-01-01

    During limb movement and locomotion, animals store elastic energy in the tendons of the feet, legs, and other limbs. In the turkey, much of the force generated by the gastrocnemius muscle during locomotion is stored as elastic energy through deformation of the tendon. During growth and development, the leg tendons in some avians, including turkeys, mineralize and result in an increase in tensile strength and modulus. The purpose of our study was to evaluate the effects of mineralization on elastic energy storage and transmission in turkey tendons. Elastic and viscous stress-strain curves and elastic energy storage behavior were used to compare the behavior of mineralized turkey gastrocnemius tendons and mineralized self-assembled type I collagen fibers. Based on analysis of these two systems, we concluded that a simple mineralized fibrillar collagenous substrate can mimic the behavior of a more complex fibrillar collagenous substrate such as mineralized turkey tendon; however, the exact mechanism of mineralization may be different between the two substrates. Changes in mechanical properties of turkey tendon were consistent with a model in which mineralization appears to increase the effective collagen fibril length by efficiently transferring stress between neighboring collagen fibrils. Mineralization in self-assembled collagen fibers increased elastic energy storage less efficiently as compared with turkey tendon suggesting that the noncollagenous components of mineralizing tissue may act to promote collagen fibril to collagen fibril interactions.

  6. [Study on the acid hydrolysis, fiber remodeling and bionics mineralization of rat tail tendon collagen type Ⅰ].

    Science.gov (United States)

    Zhang, Zhan; Zhang, Chun; Guo, Qiaofeng

    2016-05-25

    Objective: To produce bionic bone material that is consistent with human bone in chemical composition and molecular structure using rat tail tendon collagen type Ⅰ. Methods: The type Ⅰcollagen derived from rat tail was extracted by acetic acid to form collagen fibers. The reconstructed collagen fibers were placed in the mineralized solution to mimic bone mineralization for 2-6 days. Bone mineralization was observed by transmission electron microscopy and electron diffraction.Results: Collagen fibers with characteristic D-Band structure were reconstructed by using rat tail tendon collagen type Ⅰ extracted with acid hydrolysis method. Transmission electron microscopy and electron diffraction showed that calcium hydroxyapatite precursor infiltrated into the collagen fibers, and the collagen fibers were partially mineralized after 2 days of mineralization; the collagen fibers were completely mineralized and bionic bone material of typeⅠ collagen/calcium hydroxyapatite was formed after 6 days of mineralization.Conclusion: The collagen type Ⅰ can be extracted from rat tail tendon by acid hydrolysis method, and can be reformed and mineralized to form the bionic bone material which mimics human bone in chemical composition and the molecular structure.

  7. Synthesis and Fabrication of Nanocomposite Fibers of Collagen-Cellulose Nanocrystals by Coelectrocompaction.

    Science.gov (United States)

    Cudjoe, Elvis; Younesi, Mousa; Cudjoe, Edward; Akkus, Ozan; Rowan, Stuart J

    2017-04-10

    An electrochemical process has been used to compact cellulose nanocrystals (CNC) and access aligned micron-sized CNC fibers. Placing a current across aqueous solutions of carboxylic acid functionalized CNCs (t-CNC-COOH) or carboxylic acid/primary amine functionalized CNCs (t-CNC-COOH-NH2) creates a pH gradient between the electrodes, which results in the migration and concentration of the CNC fibers at their isoelectric point. By matching the carboxylic acid/amine ratio of CNCs and collagen (ca. 30:70 carboxylic acid:amine ratio), it is possible to coelectrocompact both nanofibers and access aligned nanocomposite fibers. t-CNC-COOH-NH2/collagen fibers showed a maximum increase in mechanical properties at 5 wt % of t-CNC-COOH-NH2. Compared to collagen/CNC films which have no alignment in the plane of the films, the tensile properties of the aligned fibers show a significant enhancement in the wet mechanical properties (40 MPa vs 230 MPa) for the 5 wt % of t-CNC-COOH-NH2/collagen films and fiber, respectively.

  8. Analysis of collagen fiber domain organization by Fourier second harmonic generation microscopy

    Science.gov (United States)

    Ghazaryan, Ara; Tsai, Halley F.; Hayrapetyan, Gor; Chen, Wei-Liang; Chen, Yang-Fang; Jeong, Myung Yung; Kim, Chang-Seok; Chen, Shean-Jen; Dong, Chen-Yuan

    2013-03-01

    We present an automated and systematic two-dimensional discrete Fourier transform (2D-FFT) approach to analyze collagen fiber organization through the use of second harmonic generation (SHG) microscopy. Average orientations of individual domains and Ising-like order parameters introduced to characterize the correlation between orientations of adjacent domains may be used to quantitatively characterize fibrous tissues. Our approach was applied to analyze tissues including rat tail tendon, mouse skin, bovine corneas, and human corneas. We also show that collagen fiber organization in normal and keratokonus human corneas may be distinguished. The current approach may be used for the quantitative differentiation of SHG collagen fiber morphology in different tissues and may be applied for diagnostic purposes.

  9. Morphological and molecular analysis of the collagen fibers in inflammatory process

    Science.gov (United States)

    de Carvalho, Luis Felipe das Chagas e. Silva; Alves, Mônica Ghislaine Oliveira; Soares, Carlos Alexandre; Almeida, Janete Dias; da Silva Martinho, Herculano

    2011-07-01

    Collagen makes up one third of the total protein in humans, being formed by the connection of three polypeptide chains arranged in a triple helix. This protein has fundamental importance in the formation of extracellular matrix of connective tissue. This study aimed to analyze the structural changes of collagen, which are resulting from inflammatory processes in oral mucosa, and to make the comparative analysis between the histopathology and the Raman spectra. The samples of tissues with inflammatory fibrous hyperplasia (IFH) and normal mucosa (NM) were evaluated by Raman Spectroscopy, hematoxylin-eosin and Massons trichrome stain. The histological analysis in both stains showed differences in collagen fibers, which was presented as thin fibers and arranged in parallel direction in NM and as collagen fibers are thick, mature and not organized, showing that these types of stain show morphological changes of collagen in IFH. The Raman Spectroscopy discriminate the groups of NM and IFH based on vibrational modes of proline, hydroxiproline and CH3, CH2. The histological stains only shows information from morphological data, and can be complemented by Raman spectra. This technique could demonstrate that inflammatory process caused some changes in collagen structure which is related to aminoacids such as proline and hidroxyproline.

  10. Automatic Evaluation of Collagen Fiber Directions from Polarized Light Microscopy Images.

    Science.gov (United States)

    Novak, Kamil; Polzer, Stanislav; Tichy, Michal; Bursa, Jiri

    2015-08-01

    Mechanical properties of the arterial wall depend largely on orientation and density of collagen fiber bundles. Several methods have been developed for observation of collagen orientation and density; the most frequently applied collagen-specific manual approach is based on polarized light (PL). However, it is very time consuming and the results are operator dependent. We have proposed a new automated method for evaluation of collagen fiber direction from two-dimensional polarized light microscopy images (2D PLM). The algorithm has been verified against artificial images and validated against manual measurements. Finally the collagen content has been estimated. The proposed algorithm was capable of estimating orientation of some 35 k points in 15 min when applied to aortic tissue and over 500 k points in 35 min for Achilles tendon. The average angular disagreement between each operator and the algorithm was -9.3±8.6° and -3.8±8.6° in the case of aortic tissue and -1.6±6.4° and 2.6±7.8° for Achilles tendon. Estimated mean collagen content was 30.3±5.8% and 94.3±2.7% for aortic media and Achilles tendon, respectively. The proposed automated approach is operator independent and several orders faster than manual measurements and therefore has the potential to replace manual measurements of collagen orientation via PLM.

  11. Fourier transform infrared imaging and infrared fiber optic probe spectroscopy identify collagen type in connective tissues.

    Directory of Open Access Journals (Sweden)

    Arash Hanifi

    Full Text Available Hyaline cartilage and mechanically inferior fibrocartilage consisting of mixed collagen types are frequently found together in repairing articular cartilage. The present study seeks to develop methodology to identify collagen type and other tissue components using Fourier transform infrared (FTIR spectral evaluation of matrix composition in combination with multivariate analyses. FTIR spectra of the primary molecular components of repair cartilage, types I and II collagen, and aggrecan, were used to develop multivariate spectral models for discrimination of the matrix components of the tissues of interest. Infrared imaging data were collected from bovine bone, tendon, normal cartilage, meniscus and human repair cartilage tissues, and composition predicted using partial least squares analyses. Histology and immunohistochemistry results were used as standards for validation. Infrared fiber optic probe spectral data were also obtained from meniscus (a tissue with mixed collagen types to evaluate the potential of this method for identification of collagen type in a minimally-invasive clinical application. Concentration profiles of the tissue components obtained from multivariate analysis were in excellent agreement with histology and immunohistochemistry results. Bone and tendon showed a uniform distribution of predominantly type I collagen through the tissue. Normal cartilage showed a distribution of type II collagen and proteoglycan similar to the known composition, while in repair cartilage, the spectral distribution of both types I and II collagen were similar to that observed via immunohistochemistry. Using the probe, the outer and inner regions of the meniscus were shown to be primarily composed of type I and II collagen, respectively, in accordance with immunohistochemistry data. In summary, multivariate analysis of infrared spectra can indeed be used to differentiate collagen type I and type II, even in the presence of proteoglycan, in

  12. Quantification of collagen and elastic fibers using whole-slide images of liver biopsy specimens.

    Science.gov (United States)

    Abe, Tokiya; Hashiguchi, Akinori; Yamazaki, Ken; Ebinuma, Hirotoshi; Saito, Hidetsugu; Kumada, Hiromitsu; Izumi, Namiki; Masaki, Naohiko; Sakamoto, Michiie

    2013-06-01

    Histological evaluation of fibrosis after a liver biopsy is crucial for evaluating the pathology of patients with chronic liver disease. Previous studies have reported quantitative analyses of fibrosis using images of collagen-stained sections. However, analysis of these studies requires manual selection of the region of interest. In addition, the quantification of elastic fibers is not considered. The present study was conducted in order to measure both the collagen and elastic fiber area ratios using Elastica van Gieson-stained whole-slide images (WSIs) of liver biopsy specimens. High-resolution WSIs provide precise color classification, enabling accurate detection of even fine collagen and elastic fibers. To minimize the influence of pre-existing fibrous tissue, median area ratios of the collagen and elastic fibers were independently calculated from the image tiles of the WSIs. These median area ratios were highly concordant with area ratios after the pre-existing fibrous tissues were manually trimmed from the WSI. Further, these median area ratios were correlated with liver stiffness as measured by transient elastography (collagen: r = 0.73 [P liver fibrosis will serve as an effective tool to evaluate liver diseases in routine practice.

  13. Collagen arrangement in hepatic granuloma in mice infected with Schistosoma mansoni: dependence on fiber radiation centers

    Directory of Open Access Journals (Sweden)

    H.L. Lenzi

    1999-05-01

    Full Text Available The collagen structure of isolated and in situ liver granuloma from Swiss Webster mice infected with Schistosoma mansoni was sequentially and three-dimensionally analyzed during different times of infection (early acute, acute, transitional acute-chronic, and chronic phases by laser scanning confocal microscopy and electron scanning variable vacuum microscopy. The initial granuloma structure is characterized by vascular collagen residues and by anchorage points (or fiber radiation centers, from where collagenous fibers are angularly shed and self-assembled. During the exudative-productive stage, the self-assembly of these fibers minimizes energy and mass through continuous tension and focal compression. The curvature or angles between collagen fibers probably depends on the fibroblastic or myofibroblastic organization of stress fibers. Gradually, the loose unstable lattice of the exudative-productive stage transforms into a highly packed and stable architecture as a result of progressive compactness. The three-dimensional architecture of granulomas provides increased tissue integrity, efficient distribution of soluble compounds and a haptotactic background to the cells.

  14. Regenerated collagen fibers with grooved surface texture: Physicochemical characterization and cytocompatibility.

    Science.gov (United States)

    Wang, Xiang; Wu, Tong; Wang, Wei; Huang, Chen; Jin, Xiangyu

    2016-01-01

    A novel type of protein fibers, regenerated collagen fibers (RC) from cattle skin, was prepared through wet-spinning. Due to the combined effect of solvent exchange and subsequent drawing process, the fibers were found to have a grooved surface texture. The grooves provided not only ordered topographical cues, but also increased surface area. Protein content of the RC fibers was confirmed by Fourier Transform infrared spectroscopy (FTIR) and ninhydrin color reaction. The fibers could be readily fabricated into nonwovens or other textiles, owning to their comparable physical properties to other commercialized fibers. Cell growth behavior on RC nonwovens suggested both early adhesion and prompt proliferation. The high moisture regain, good processability, along with the excellent cytocompatibility indicated that the RC fibers and nonwovens developed in this study might offer a good candidate for biomedical and healthcare applications.

  15. Regenerated collagen fibers with grooved surface texture: Physicochemical characterization and cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Wu, Tong [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Wang, Wei [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Huang, Chen, E-mail: hc@dhu.edu.cn [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Jin, Xiangyu [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China)

    2016-01-01

    A novel type of protein fibers, regenerated collagen fibers (RC) from cattle skin, was prepared through wet-spinning. Due to the combined effect of solvent exchange and subsequent drawing process, the fibers were found to have a grooved surface texture. The grooves provided not only ordered topographical cues, but also increased surface area. Protein content of the RC fibers was confirmed by Fourier Transform infrared spectroscopy (FTIR) and ninhydrin color reaction. The fibers could be readily fabricated into nonwovens or other textiles, owning to their comparable physical properties to other commercialized fibers. Cell growth behavior on RC nonwovens suggested both early adhesion and prompt proliferation. The high moisture regain, good processability, along with the excellent cytocompatibility indicated that the RC fibers and nonwovens developed in this study might offer a good candidate for biomedical and healthcare applications. - Highlights: • Wet-spun regenerated collagen fibers having aligned surface grooves • Comparable physiochemical properties to commercialized fibers • Readily processed into nonwovens • Excellent cytocompatibility with prompt cell adhesion and proliferation.

  16. Arrangement of collagen fibers in human placental stem villi

    NARCIS (Netherlands)

    Sati, Leyla; Demir, Ayse Yasemin; Sarikcioglu, Levent; Demir, Ramazan

    2008-01-01

    The aim of the study was to investigate the arrangements and related localization patterns of different collagen types in the stroma of placental stem villi by immunohistochemistry and electron microscopy. A total of 14 normal human term placental tissue samples were studied. Immunohistochemistry wa

  17. Arrangement of collagen fibers in human placental stem villi

    NARCIS (Netherlands)

    Sati, Leyla; Demir, Ayse Yasemin; Sarikcioglu, Levent; Demir, Ramazan

    2008-01-01

    The aim of the study was to investigate the arrangements and related localization patterns of different collagen types in the stroma of placental stem villi by immunohistochemistry and electron microscopy. A total of 14 normal human term placental tissue samples were studied. Immunohistochemistry

  18. Quantifying collagen fiber orientation in breast cancer using quantitative phase imaging

    Science.gov (United States)

    Majeed, Hassaan; Okoro, Chukwuemeka; Kajdacsy-Balla, André; Toussaint, Kimani C., Jr.; Popescu, Gabriel

    2017-04-01

    Tumor progression in breast cancer is significantly influenced by its interaction with the surrounding stromal tissue. Specifically, the composition, orientation, and alignment of collagen fibers in tumor-adjacent stroma affect tumor growth and metastasis. Most of the work done on measuring this prognostic marker has involved imaging of collagen fibers using second-harmonic generation microscopy (SHGM), which provides label-free specificity. Here, we show that spatial light interference microscopy (SLIM), a label-free quantitative phase imaging technique, is able to provide information on collagen-fiber orientation that is comparable to that provided by SHGM. Due to its wide-field geometry, the throughput of the SLIM system is much higher than that of SHGM and, because of the linear imaging, the equipment is simpler and significantly less expensive. Our results indicate that SLIM images can be used to extract important prognostic information from collagen fibers in breast tissue, potentially providing a convenient high throughput clinical tool for assessing patient prognosis.

  19. Treatment time of ultrasound therapy interferes with the organization of collagen fibers in rat tendons

    Directory of Open Access Journals (Sweden)

    Thiago S. Farcic

    2013-06-01

    Full Text Available BACKGROUND: The application time of therapeutic ultrasound is an infrequently studied dosimetric variable that affects tissue repair. OBJECTIVES: The aim of this study was to evaluate the effects of different treatment times of therapeutic ultrasound (US on the organization of collagen fibers in the tendons of rats. METHOD: Forty Wistar rats were selected (300±45 g, and the rats were divided into five groups (n=8 for each group: Control, without tenotomy or any treatment; tenotomy group, with tenotomy and without treatment; US groups (US1, US2, and US3, subjected to tenotomy and treated with US for one, two, or three minutes per area of the transducer, respectively. The animals were sacrificed on the 12th post-operative day, and the tendons were surgically removed for analyses of the collagen fiber organization by means of birefringence analysis. RESULTS: The collagen fibers exhibited better aggregation and organization in the US3 group compared with the tenotomy group (p<0.05. CONCLUSIONS: The findings suggest that US applied for three minutes per treated area improves the organization of collagen fibers during rat tendon repair.

  20. Time-evolving collagen-like structural fibers in soft tissues: biaxial loading and spherical inflation

    Science.gov (United States)

    Topol, Heiko; Demirkoparan, Hasan; Pence, Thomas J.; Wineman, Alan

    2016-05-01

    This work considers a previously developed constitutive theory for the time dependent mechanical response of fibrous soft tissue resulting from the time dependent remodeling of a collagen fiber network that is embedded in a ground substance matrix. The matrix is taken to be an incompressible nonlinear elastic solid. The remodeling process consists of the continual dissolution of existing fibers and the creation of new fibers. Motivated by experimental reports on the enzyme degradation of collagen fibers, the remodeling is governed by first order chemical kinetics such that the dissolution rate is dependent upon the fiber stretch. The resulting time dependent mechanical response is sensitive to the natural configuration of the fibers when they are created, and different assumptions on the nature of the fiber's stress free state are considered here. The response under biaxial loading, a type of loading that has particular significance for the characterization of biological materials, is studied. The inflation of a spherical membrane is then analyzed in terms of the equal biaxial stretch that occurs in the membrane approximation. Different assumptions on the natural configuration of the fibers, combined with their time dependent dissolution and reforming, are shown to emulate alternative forms of creep and relaxation response. This formal similarity to viscoelastic phenomena occurs even though the underlying mechanisms are fundamentally different from the mechanism of macromolecular reconfiguration that one typically associates with viscoelastic response.

  1. Second-harmonic generation reveals a relationship between metastatic potential and collagen fiber structure

    Science.gov (United States)

    Burke, Kathleen A.; Dawes, Ryan P.; Cheema, Mehar K.; Perry, Seth; Brown, Edward

    2014-02-01

    Second Harmonic Generation (SHG) of collagen signals allows for the analysis of collagen structural changes throughout metastatic progression. The directionality of coherent SHG signals, measured through the ratio of the forward-propagating to backward propagating signal (F/B ratio), is affected by fibril diameter, spacing, and order versus disorder of fibril packing within a fiber. As tumors interact with their microenvironment and metastasize, it causes changes in these parameters, and concurrent changes in the F/B ratio. Specifically, the F/B ratio of breast tumors that are highly metastatic to the lymph nodes is significantly higher than those in tumors with restricted lymph node involvement. We utilized in vitro analysis of tumor cell motility through collagen gels of different microstructures, and hence different F/B ratios, to explore the relationship between collagen microstructures and metastatic capabilities of the tumor. By manipulating environmental factors of fibrillogenesis and biochemical factors of fiber composition we created methods of varying the average F/B ratio of the gel, with significant changes in fiber structure occurring as a result of alterations in incubation temperature and increasing type III collagen presence. A migration assay was performed using simultaneous SHG and fluorescent imaging to measure average penetration depth of human tumor cells into the gels of significantly different F/B ratios, with preliminary data demonstrating that cells penetrate deeper into gels of higher F/B ratio caused by lower type III collagen concentration. Determining the role of collagen structure in tumor cell motility will aid in the future prediction metastatic capabilities of a primary tumor.

  2. Interaction between hepatocytes and collagen gel in hollow fibers

    OpenAIRE

    Dai, Jing; ZHANG Guo-liang; Meng, Qin

    2009-01-01

    Gel entrapment culture of primary mammalian cells within collagen gel is one important configuration for construction of bioartificial organ as well as in vitro model for predicting drug situation in vivo. Gel contraction in entrapment culture, resulting from cell-mediated reorganization of the extracellular matrix, was commonly used to estimate cell viability. However, the exact influence of gel contraction on cell activities has rarely been addressed. This paper investigated the gel contrac...

  3. Finite strain response of crimped fibers under uniaxial traction: An analytical approach applied to collagen

    Science.gov (United States)

    Marino, Michele; Wriggers, Peter

    2017-01-01

    Composite materials reinforced by crimped fibers intervene in a number of advanced structural applications. Accordingly, constitutive equations describing their anisotropic behavior and explicitly accounting for fiber properties are needed for modeling and design purposes. To this aim, the finite strain response of crimped beams under uniaxial traction is herein addressed by obtaining analytical relationships based on the Principle of Virtual Works. The model is applied to collagen fibers in soft biological tissues, coupling geometric nonlinearities related to fiber crimp with material nonlinearities due to nanoscale mechanisms. Several numerical applications are presented, addressing the influence of geometric and material features. Available experimental data for tendons are reproduced, integrating the proposed approach within an optimization procedure for data fitting. The obtained results highlight the effectiveness of the proposed approach in correlating fibers structure with composite material mechanics.

  4. Contribution of collagen fiber undulation to regional biomechanical properties along porcine thoracic aorta.

    Science.gov (United States)

    Zeinali-Davarani, Shahrokh; Wang, Yunjie; Chow, Ming-Jay; Turcotte, Raphaël; Zhang, Yanhang

    2015-05-01

    As major extracellular matrix components, elastin, and collagen play crucial roles in regulating the mechanical properties of the aortic wall and, thus, the normal cardiovascular function. The mechanical properties of aorta, known to vary with age and multitude of diseases as well as the proximity to the heart, have been attributed to the variations in the content and architecture of wall constituents. This study is focused on the role of layer-specific collagen undulation in the variation of mechanical properties along the porcine descending thoracic aorta. Planar biaxial tensile tests are performed to characterize the hyperelastic anisotropic mechanical behavior of tissues dissected from four locations along the thoracic aorta. Multiphoton microscopy is used to image the associated regional microstructure. Exponential-based and recruitment-based constitutive models are used to account for the observed mechanical behavior while considering the aortic wall as a composite of two layers with independent properties. An elevated stiffness is observed in distal regions compared to proximal regions of thoracic aorta, consistent with sharper and earlier collagen recruitment estimated for medial and adventitial layers in the models. Multiphoton images further support our prediction that higher stiffness in distal regions is associated with less undulation in collagen fibers. Recruitment-based models further reveal that regardless of the location, collagen in the media is recruited from the onset of stretching, whereas adventitial collagen starts to engage with a delay. A parameter sensitivity analysis is performed to discriminate between the models in terms of the confidence in the estimated model parameters.

  5. Electrically conducting nanobiocomposites using carbon nanotubes and collagen waste fibers

    Energy Technology Data Exchange (ETDEWEB)

    Meiyazhagan, Ashokkumar; Thangavel, Saravanamoorthy [Advanced Materials Laboratory, Center for Leather Apparel & Accessories Development, Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India); Hashim, Daniel P.; Ajayan, Pulickel M. [Department of Materials Science and NanoEngineering, Rice University, Houston, TX 77005 (United States); Palanisamy, Thanikaivelan, E-mail: thanik8@yahoo.com [Advanced Materials Laboratory, Center for Leather Apparel & Accessories Development, Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India)

    2015-05-01

    Electrically conducting hybrid biocomposite films were prepared using a simple and cost-effective method by incorporating different types of carbon nanotubes (XCNTs) viz., few walled carbon nanotube (FWCNT) and boron doped carbon nanotube (BCNT) into biopolymers. Collagen extracted from animal skin wastes was blended with guar gum and XCNTs in varying proportions to form flexible and electrically conducting hybrid films. We found that the electrical conductivity of both types of hybrid films increases radically as the XCNT loading increases. BCNT incorporated hybrid films show better electrical conductivity (3.0 × 10{sup −1} S/cm) than their FWCNT loaded counter parts (4.8 × 10{sup −4} S/cm) at a dosage of 2 wt.%. On the other hand, mechanical and other physical properties such as transparency, flexibility and surface smoothness of the developed hybrid films were affected as a function of XCNT concentration. We also demonstrated that the developed hybrid films lit up a LED lamp when inserted between batteries and the brightness of the emitted light depended on the XCNT loading. These results suggest a new way to transform an industrial biowaste into innovative advanced materials for applications in fields related to biomedicine, biosensors and electronics. - Highlights: • Hybrid nanobiocomposite films prepared using collagen, guar gum and CNTs. • Examined the effect of CNT doping on the properties of hybrid biocomposite films. • Higher CNT loading improved the conductivity radically, especially for BCNT. • The ability of developed hybrid films to lit up a LED lamp was demonstrated. • The results suggest a new way to transform biowaste into advanced materials.

  6. Towards Tuning the Mechanical Properties of Three-Dimensional Collagen Scaffolds Using a Coupled Fiber-Matrix Model

    Directory of Open Access Journals (Sweden)

    Shengmao Lin

    2015-08-01

    Full Text Available Scaffold mechanical properties are essential in regulating the microenvironment of three-dimensional cell culture. A coupled fiber-matrix numerical model was developed in this work for predicting the mechanical response of collagen scaffolds subjected to various levels of non-enzymatic glycation and collagen concentrations. The scaffold was simulated by a Voronoi network embedded in a matrix. The computational model was validated using published experimental data. Results indicate that both non-enzymatic glycation-induced matrix stiffening and fiber network density, as regulated by collagen concentration, influence scaffold behavior. The heterogeneous stress patterns of the scaffold were induced by the interfacial mechanics between the collagen fiber network and the matrix. The knowledge obtained in this work could help to fine-tune the mechanical properties of collagen scaffolds for improved tissue regeneration applications.

  7. Influence of oxazolidines and zirconium oxalate crosslinkers on the hydrothermal, enzymatic, and thermo mechanical stability of type 1 collagen fiber

    Energy Technology Data Exchange (ETDEWEB)

    Haroun, Mahdi A. [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM, Serdang (Malaysia)], E-mail: Mahdiupm@hotmail.com; Khirstova, Palmina K. [People' s Hall 11113, P.O. Box 6272, Khartoum (Sudan); Gasmelseed, Gurashi A. [Juba University, Leather Dept. P.O. Box 12327 Khartoum (Sudan); Covington, Antony D. [Leather Centre, University College Northampton, Northampton (United Kingdom)

    2009-02-20

    Stabilization of type I rat tail tendon (RTT) collagen by crosslink agent oxazolidine and zirconium oxalate was studied to understand the effect on the thermal, enzymatic and mechanical stability of collagen. The results show that both oxazolidine and zirconium oxalate imparts thermal stability to collagen, and oxazolidine exhibits a marked increase in the peak temperature and enthalpy changes when compared to both native and zirconium oxalate tanned RTT. There is a decrease in the peak temperature and the enthalpy changes of oxazolidine tanned RTT fibers after treatment with urea, suggesting the possibility of alterations in the secondary structure of collagen after tanning. Oxazolidine, which forms carbocationic intermediates species in solution, have better crosslinking with collagen as seen from viscometry studies and hence provides better enzymatic stability to collagen than zirconium, which largely forms monomeric species in solution. Zirconium does not seem to change the tensile strength of RTT fibers significantly in wet condition as well as oxazolidine.

  8. Use of Natural Neural Scaffolds Consisting of Engineered Vascular Endothelial Growth Factor Immobilized on Ordered Collagen Fibers Filled in a Collagen Tube for Peripheral Nerve Regeneration in Rats

    Directory of Open Access Journals (Sweden)

    Fukai Ma

    2014-10-01

    Full Text Available The search for effective strategies for peripheral nerve regeneration has attracted much attention in recent years. In this study, ordered collagen fibers were used as intraluminal fibers after nerve injury in rats. Vascular endothelial growth factor (VEGF plays an important role in nerve regeneration, but its very fast initial burst of activity within a short time has largely limited its clinical use. For the stable binding of VEGF to ordered collagen fibers, we fused a collagen-binding domain (CBD to VEGF through recombinant DNA technology. Then, we filled the ordered collagen fibers-CBD-VEGF targeting delivery system in a collagen tube to construct natural neural scaffolds, which were then used to bridge transected nerve stumps in a rat sciatic nerve transection model. After transplantation, the natural neural scaffolds showed minimal foreign body reactions and good integration into the host tissue. Oriented collagen fibers in the collagen tube could guide regenerating axons in an oriented manner to the distal, degenerating nerve segment, maximizing the chance of target reinnervation. Functional and histological analyses indicated that the recovery of nerve function in the natural neural scaffolds-treated group was superior to the other grafted groups. The guiding of oriented axonal regeneration and effective delivery systems surmounting the otherwise rapid and short-lived diffusion of growth factors in body fluids are two important strategies in promoting peripheral nerve regeneration. The natural neural scaffolds described take advantage of these two aspects and may produce synergistic effects. These properties qualified the artificial nerve conduits as a putative candidate system for the fabrication of peripheral nerve reconstruction devices.

  9. Use of natural neural scaffolds consisting of engineered vascular endothelial growth factor immobilized on ordered collagen fibers filled in a collagen tube for peripheral nerve regeneration in rats.

    Science.gov (United States)

    Ma, Fukai; Xiao, Zhifeng; Meng, Danqing; Hou, Xianglin; Zhu, Jianhong; Dai, Jianwu; Xu, Ruxiang

    2014-10-15

    The search for effective strategies for peripheral nerve regeneration has attracted much attention in recent years. In this study, ordered collagen fibers were used as intraluminal fibers after nerve injury in rats. Vascular endothelial growth factor (VEGF) plays an important role in nerve regeneration, but its very fast initial burst of activity within a short time has largely limited its clinical use. For the stable binding of VEGF to ordered collagen fibers, we fused a collagen-binding domain (CBD) to VEGF through recombinant DNA technology. Then, we filled the ordered collagen fibers-CBD-VEGF targeting delivery system in a collagen tube to construct natural neural scaffolds, which were then used to bridge transected nerve stumps in a rat sciatic nerve transection model. After transplantation, the natural neural scaffolds showed minimal foreign body reactions and good integration into the host tissue. Oriented collagen fibers in the collagen tube could guide regenerating axons in an oriented manner to the distal, degenerating nerve segment, maximizing the chance of target reinnervation. Functional and histological analyses indicated that the recovery of nerve function in the natural neural scaffolds-treated group was superior to the other grafted groups. The guiding of oriented axonal regeneration and effective delivery systems surmounting the otherwise rapid and short-lived diffusion of growth factors in body fluids are two important strategies in promoting peripheral nerve regeneration. The natural neural scaffolds described take advantage of these two aspects and may produce synergistic effects. These properties qualified the artificial nerve conduits as a putative candidate system for the fabrication of peripheral nerve reconstruction devices.

  10. Quantitative mapping of collagen fiber alignment in thick tissue samples using transmission polarized-light microscopy.

    Science.gov (United States)

    Yakovlev, Dmitry D; Shvachkina, Marina E; Sherman, Maria M; Spivak, Andrey V; Pravdin, Alexander B; Yakovlev, Dmitry A

    2016-07-01

    Immersion optical clearing makes it possible to use transmission polarized-light microscopy for characterization of thick (200 to 2000  μm) layers of biological tissues. We discuss polarization properties of thick samples in the context of the problem of characterization of collagen fiber alignment in connective tissues such as sclera and dermis. Optical chirality caused by azimuthal variations of the macroscopic (effective) optic axis of the medium across the sample thickness should be considered in polarization mapping of thick samples of these tissues. We experimentally evaluate to what extent the optical chirality affects the measurement results in typical situations and show under what conditions it can be easily taken into account and does not hinder, but rather helps, in characterization of collagen fiber alignment.

  11. Rapid three-dimensional quantification of voxel-wise collagen fiber orientation.

    Science.gov (United States)

    Liu, Zhiyi; Quinn, Kyle P; Speroni, Lucia; Arendt, Lisa; Kuperwasser, Charlotte; Sonnenschein, Carlos; Soto, Ana M; Georgakoudi, Irene

    2015-07-01

    Defining fiber orientation at each voxel within a 3D biomedical image stack is potentially useful for a variety of applications, including cancer, wound healing and tissue regeneration. Current methods are typically computationally intensive or inaccurate. Herein, we present a 3D weighted orientation vector summation algorithm, which is a generalization of a previously reported 2D vector summation technique aimed at quantifying collagen fiber orientations simultaneously at each voxel of an image stack. As a result, voxel-wise fiber orientation information with 4° to 5° accuracy can be determined, and the computational time required to analyze a typical stack with the size of 512x512x100 voxels is less than 5 min. Thus, this technique enables the practical extraction of voxel-specific orientation data for characterizing structural anisotropy in 3D specimens. As examples, we use this approach to characterize the fiber organization in an excised mouse mammary gland and a 3D breast tissue model.

  12. Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces

    OpenAIRE

    Adams, K.; Schulz-Kornas, E; Arzi, B.; Failing, K.; Vogelsberg, J; Staszyk, C

    2016-01-01

    In the last decade, the equine masticatory apparatus has received much attention. Numerous studies have emphasized the importance of the temporomandibular joint (TMJ) in the functional process of mastication. However, ultrastructural and histological data providing a basis for biomechanical and histopathological considerations are not available. The aim of the present study was to analyze the architecture of the collagen fiber apparatus in the articular surfaces of the equine TMJ to reveal ty...

  13. Incorporation of experimentally-derived fiber orientation into a structural constitutive model for planar collagenous tissues.

    Science.gov (United States)

    Sacks, Michael S

    2003-04-01

    Structural constitutive models integrate information on tissue composition and structure, avoiding ambiguities in material characterization. However, critical structural information (such as fiber orientation) must be modeled using assumed statistical distributions, with the distribution parameters estimated from fits to the mechanical test data. Thus, full realization of structural approaches continues to be limited without direct quantitative structural information for direct implementation or to validate model predictions. In the present study, fiber orientation information obtained using small angle light scattering (SALS) was directly incorporated into a structural constitutive model based on work by Lanir (J. Biomech., v. 16, pp. 1-12, 1983). Demonstration of the model was performed using existing biaxial mechanical and fiber orientation data for native bovine pericardium (Sacks and Chuong, ABME, v.26, pp. 892-902, 1998). The structural constitutive model accurately predicted the complete measured biaxial mechanical response. An important aspect of this approach is that only a single equibiaxial test to determine the effective fiber stress-strain response and the SALS-derived fiber orientation distribution were required to determine the complete planar biaxial mechanical response. Changes in collagen fiber crimp under equibiaxial strain suggest that, at the meso-scale, fiber deformations follow the global tissue strains. This result supports the assumption of affine strain to estimate the fiber strains. However, future evaluations will have to be performed for tissue subjected to a wider range of strain to more fully validate the current approach.

  14. Quantification of collagen fiber orientation in human tendons with the coefficient of variation of echogenicity.

    Science.gov (United States)

    Ishigaki, Tomonobu; Kouno, Masahiro; Ikebukuro, Toshihiro; Kubo, Keitaro

    2016-12-08

    The grayscale distribution on the ultrasonic images of tendons may be reduced with alignment of collagen fibers, because ultrasound signal intensity changes with alterations in tendon collagen fiber orientation due to acoustic anisotropy in the tendons. The purpose of this study was to investigate changes in the coefficient of variation (CV) of echogenicity in the Achilles tendon during passive dorsiflexion (the angle task) and isometric plantar flexion (the contraction task). Achilles tendon transverse ultrasonic images were collected from 14 healthy individuals every 10° from 20° to -20° (positive values for plantar flexion) in the angle task and every 10% maximum voluntary contraction (MVC) from 0% to 70% MVC in the contraction task. The CV of echogenicity was measured in each image. In addition, relative changes in the measured variables between the former half (20-0° in the angle task, 0% to 30% MVC in the contraction task) and the latter half (0° to -20° in the angle task, 40% to 70% MVC in the contraction task) of each task were compared. The CV of echogenicity decreased with increases in the dorsiflexion angle and intensity of isometric contractions. Furthermore, relative changes in the CV of echogenicity were greater at more dorsiflexed positions in the angle task and at lower torque levels in the contraction task. These results suggested that decreases in the CV of echogenicity were partially related to the alignment of the tendon collagen fibers with tendon stretching. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Collagen fibers mediate MRI-detected water diffusion and anisotropy in breast cancers.

    Science.gov (United States)

    Kakkad, Samata; Zhang, Jiangyang; Akhbardeh, Alireza; Jacob, Desmond; Krishnamachary, Balaji; Solaiyappan, Meiyappan; Jacobs, Michael A; Raman, Venu; Leibfritz, Dieter; Glunde, Kristine; Bhujwalla, Zaver M

    2016-10-01

    Collagen 1 (Col1) fibers play an important role in tumor interstitial macromolecular transport and cancer cell dissemination. Our goal was to understand the influence of Col1 fibers on water diffusion, and to examine the potential of using noninvasive diffusion tensor imaging (DTI) to indirectly detect Col1 fibers in breast lesions. We previously observed, in human MDA-MB-231 breast cancer xenografts engineered to fluoresce under hypoxia, relatively low amounts of Col1 fibers in fluorescent hypoxic regions. These xenograft tumors together with human breast cancer samples were used here to investigate the relationship between Col1 fibers, water diffusion and anisotropy, and hypoxia. Hypoxic low Col1 fiber containing regions showed decreased apparent diffusion coefficient (ADC) and fractional anisotropy (FA) compared to normoxic high Col1 fiber containing regions. Necrotic high Col1 fiber containing regions showed increased ADC with decreased FA values compared to normoxic viable high Col1 fiber regions that had increased ADC with increased FA values. A good agreement of ADC and FA patterns was observed between in vivo and ex vivo images. In human breast cancer specimens, ADC and FA decreased in low Col1 containing regions. Our data suggest that a decrease in ADC and FA values observed within a lesion could predict hypoxia, and a pattern of high ADC with low FA values could predict necrosis. Collectively the data identify the role of Col1 fibers in directed water movement and support expanding the evaluation of DTI parameters as surrogates for Col1 fiber patterns associated with specific tumor microenvironments as companion diagnostics and for staging.

  16. The optimization of bovine tendon collagen fiber extraction conditions and structural characterization of collagen fiber%牛肌腱胶原纤维提取条件优化及其结构表征

    Institute of Scientific and Technical Information of China (English)

    刘新华; 但年华; 胡杨; 肖世维; 但卫华

    2012-01-01

    Collagen fibers were extracted by acid swelling-pepsin digestion method from bovine tendons. Compared with the extraction rate of the collagen fibers and the content of soluble collagen in the collagen fibers under the conditions of different time, pH, the enzyme dosage, the optimum project was arrived at. Then collagen fibers were characterized by SDS-PAGE, IR spectra, differential scanning calorimeter (DSC) and atomic force microscope (AFM), scanning electron microscopic (SEM). The result shows that the optimized conditions were 40h,pH 2. 5, 1.0% pepsin. Relatively collagen fibers both had high extraction ratio and high molecular weight. The tests of DSC revealed that the denature temperature of collagen fibers was 66. 7'C. The pore sizes of collagen fibers were about 100-300μm by SEM. With the AFM observed, we drew a conclusion that the aggregation state of collagen fibers was complex including a single fiber and fiber bundles structure. SEM also confirms the conclusion of AFM. As a consequence, the collagen fibrils sustain original triple helix structure.%以牛肌腱为原料,通过酸-酶结合法提取胶原纤维,比较不同时间、pH值、酶用量下的胶原纤维提取率以及可溶性胶原含量,从而得到提取胶原纤维最优工艺,并用SDS-PAGE电泳、DSC、IR、SEM、AFM对胶原纤维进行了结构表征.研究结果表明,在4℃下,酸-酶结合法水解的最佳条件为,时间40h、pH值为2.5、酶用量1.0%.该条件下所得胶原纤维提取率较高,红外特征峰明显,分子量大且分布窄,变性温度为66.7℃;SEM显示胶原纤维呈现孔隙均匀的三维网状结构,孔径约为100~300μm;AFM观察到胶原纤维以单根原纤维、纤维束等形式存在,明暗相间的横纹间距为60.35nm.综合认为制备得到了具有天然三股螺旋结构的胶原纤维.

  17. An Agent-Based Discrete Collagen Fiber Network Model of Dynamic Traction Force-Induced Remodeling.

    Science.gov (United States)

    Reinhardt, James W; Gooch, Keith

    2017-09-21

    We developed an agent-based model that incorporates repetitively applied traction force within a discrete fiber network to understand how microstructural properties of the network influence mechanical properties and traction force-induced remodeling. An important difference between our model and similar finite-element models is that by implementing more biologically-realistic dynamic traction, we can explore a greater range of matrix remodeling. Here, we validated our model by reproducing qualitative trends observed in three sets of experimental data reported by others: tensile and shear testing of cell-free collagen gels, collagen remodeling around a single isolated cell, and collagen remodeling between pairs of cells. In response to tensile and shear strain, simulated acellular networks exhibited biphasic stress-strain curves indicative of strain-stiffening. Our data support the notion that strain-stiffening might occur as individual fibrils successively align along the axis of strain and become engaged in tension. In simulations with a single, contractile cell, peak collagen displacement occurred closest to the cell and decreased with increasing distance. In simulations with two cells, compaction of collagen between cells appeared inversely related to the initial distance between cells. Further analysis revealed strain energy was relatively uniform around the outer surface of cells separated by 250 microns, but became increasingly non-uniform as the distance between cells decreased. This pattern was partly attributable to the pattern of collagen compaction. These findings are of interest because fibril alignment, density, and strain energy may each contribute to contact guidance during tissue morphogenesis.

  18. Role of 17 beta-estradiol on type IV collagen fibers volumetric density in the basement membrane of bladder wall.

    Science.gov (United States)

    de Fraga, Rogerio; Dambros, Miriam; Miyaoka, Ricardo; Riccetto, Cássio Luís Zanettini; Palma, Paulo César Rodrigues

    2007-10-01

    The authors quantified the type IV collagen fibers volumetric density in the basement membrane of bladder wall of ovariectomized rats with and without estradiol replacement. This study was conducted on 40 Wistar rats (3 months old) randomly divided in 4 groups: group 1, remained intact (control); group 2, submitted to bilateral oophorectomy and daily replacement 4 weeks later of 17 beta-estradiol for 12 weeks; group 3, sham operated and daily replacement 4 weeks later of sesame oil for 12 weeks; and group 4, submitted to bilateral oophorectomy and killed after 12 weeks. It was used in immunohistochemistry evaluation using type IV collagen polyclonal antibody to stain the fibers on paraffin rat bladder sections. The M-42 stereological grid system was used to analyze the fibers. Ovariectomy had an increase effect on the volumetric density of the type IV collagen fibers in the basement membrane of rat bladder wall. Estradiol replacement in castrated animals demonstrated a significative difference in the stereological parameters when compared to the castrated group without hormonal replacement. Surgical castration performed on rats induced an increasing volumetric density of type IV collagen fibers in the basement membrane of rats bladder wall and the estradiol treatment had a significant effect in keeping a low volumetric density of type IV collagen fibers in the basement membrane of rats bladder wall.

  19. Enhanced osteoprogenitor elongated collagen fiber matrix formation by bioactive glass ionic silicon dependent on Sp7 (osterix) transcription.

    Science.gov (United States)

    Varanasi, Venu G; Odatsu, Tetsurou; Bishop, Timothy; Chang, Joyce; Owyoung, Jeremy; Loomer, Peter M

    2016-10-01

    Bioactive glasses release ions, those enhance osteoblast collagen matrix synthesis and osteogenic marker expression during bone healing. Collagen matrix density and osteogenic marker expression depend on osteogenic transcription factors, (e.g., Osterix (OSX)). We hypothesize that enhanced expression and formation of collagen by Si(4+) depends on enhanced expression of OSX transcription. Experimental bioactive glass (6P53-b) and commercial Bioglass(TM) (45S5) were dissolved in basal medium to make glass conditioned medium (GCM). ICP-MS analysis was used to measure bioactive glass ion release rates. MC3T3-E1 cells were cultured for 20 days, and gene expression and extracellular matrix collagen formation was analyzed. In a separate study, siRNA was used to determine the effect of OSX knockdown on impacting the effect of Si(4+) on osteogenic markers and matrix collagen formation. Each bioactive glass exhibited similar ion release rates for all ions, except Mg(2+) released by 6P53-b. Gene expression results showed that GCM markedly enhanced many osteogenic markers, and 45S5 GCM showed higher levels of expression and collagen matrix fiber bundle density than 6P53-b GCM. Upon knockdown of OSX transcription, collagen type 5, alkaline phosphatase, and matrix density were not enhanced as compared to wild type cells. This study illustrates that the enhancement of elongated collagen fiber matrix formation by Si(±) depends on OSX transcription. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2604-2615, 2016.

  20. Microscopic analysis of the iliofemoral and ischiofemoral ligaments in the hip joint: collagen fiber direction and crimp distribution.

    Science.gov (United States)

    Sato, Kaori; Uchiyama, Eiichi; Katayose, Masaki; Fujimiya, Mineko

    2012-03-01

    Since no previous studies have described the functional significance of the iliofemoral and ischiofemoral ligaments on the basis of microscopic analyses, we examined the direction of collagen fiber alignment and crimp distribution of the collagen fibers in sections cut in different directions. Polarized microscopic images of sections along the longitudinal (L) and transverse (T) planes of each ligament were obtained from 20 cadavers (8 males and 12 females, age at death 81.7 ± 9.4 years old). Results showed that the microscopic direction of collagen fibers in the iliofemoral ligament was parallel to the macroscopic direction, suggesting that this ligament may play a part in restricting extension of the hip joint. In contrast, the microscopic direction of collagen fibers in the ischiofemoral ligament was not parallel to the macroscopic direction, suggesting that this ligament may contribute not only to the restriction of medial rotation but also retstriction of flexion of the hip joint. From the low density of the crimp distribution in the L plane, the iliofemoral ligament may contribute to stability of the hip joint in the standing position in the living body. In conclusion, the microscopic observations of the direction of collagen fibers as well as the crimp distribution shown in the present study provide a better understanding of the functional significance of the iliofemoral and ischiofemoral ligaments.

  1. Image correlation based method for the analysis of collagen fibers patterns

    Science.gov (United States)

    Rosa, Ramon G. T.; Pratavieira, Sebastião.; Kurachi, Cristina

    2015-06-01

    The collagen fibers are one of the most important structural proteins in skin, being responsible for its strength and flexibility. It is known that their properties, like fibers density, ordination and mean diameter can be affected by several skin conditions, what makes these properties a good parameter to be used on the diagnosis and evaluation of skin aging, cancer, healing, among other conditions. There is, however, a need for methods capable of analyzing quantitatively the organization patterns of these fibers. To address this need, we developed a method based on the autocorrelation function of the images that allows the construction of vector field plots of the fibers directions and does not require any kind of curve fitting or optimization. The analyzed images were obtained through Second Harmonic Generation Imaging Microscopy. This paper presents a concise review on the autocorrelation function and some of its applications to image processing, details the developed method and the results obtained through the analysis of hystopathological slides of landrace porcine skin. The method has high accuracy on the determination of the fibers direction and presents high performance. We look forward to perform further studies keeping track of different skin conditions over time.

  2. Orientation analysis of collagen fibers in healing tendon by using second-harmonic-generation microscopy

    Science.gov (United States)

    Hase, E.; Minamikawa, T.; Sato, K.; Yonekura, D.; Takahashi, M.; Yasui, T.

    2017-02-01

    Tendon rupture is a trauma that is difficult to fully recover from. Therefore, non-destructive and non-invasive evaluation method for the tendon healing is strongly required. In this study, we performed the orientation analysis of collagen fiber in healing tendon by two-dimensional Fourier transform (2D-FT) of SHG image. The extracted 2D-FT power spectra imply the correlation with the degree of the tendon healing. These results indicate that SHG microscopy has a unique potential as a non-destructive and non-invasive indicator of tendon healing.

  3. A mechanistic model on the role of "radially-running" collagen fibers on dissection properties of human ascending thoracic aorta.

    Science.gov (United States)

    Pal, Siladitya; Tsamis, Alkiviadis; Pasta, Salvatore; D'Amore, Antonio; Gleason, Thomas G; Vorp, David A; Maiti, Spandan

    2014-03-21

    Aortic dissection (AoD) is a common condition that often leads to life-threatening cardiovascular emergency. From a biomechanics viewpoint, AoD involves failure of load-bearing microstructural components of the aortic wall, mainly elastin and collagen fibers. Delamination strength of the aortic wall depends on the load-bearing capacity and local micro-architecture of these fibers, which may vary with age, disease and aortic location. Therefore, quantifying the role of fiber micro-architecture on the delamination strength of the aortic wall may lead to improved understanding of AoD. We present an experimentally-driven modeling paradigm towards this goal. Specifically, we utilize collagen fiber micro-architecture, obtained in a parallel study from multi-photon microscopy, in a predictive mechanistic framework to characterize the delamination strength. We then validate our model against peel test experiments on human aortic strips and utilize the model to predict the delamination strength of separate aortic strips and compare with experimental findings. We observe that the number density and failure energy of the radially-running collagen fibers control the peel strength. Furthermore, our model suggests that the lower delamination strength previously found for the circumferential direction in human aorta is related to a lower number density of radially-running collagen fibers in that direction. Our model sets the stage for an expanded future study that could predict AoD propagation in patient-specific aortic geometries and better understand factors that may influence propensity for occurrence.

  4. Hg(II) removal from aqueous solution by bayberry tannin-immobilized collagen fiber.

    Science.gov (United States)

    Huang, Xin; Liao, Xuepin; Shi, Bi

    2009-10-30

    A novel adsorbent was prepared by immobilizing barberry tannin (BT) onto collagen fiber, which was found effective to remove Hg(II) from aqueous solution. The bayberry tannin-immobilized collagen fiber (BTICF) shows high adsorption capacity to Hg(II) in a wide pH range of 4.0-9.0, and a maximum adsorption capacity (198.49 mg/g) was reached at pH 7.0 and 303 K when the initial concentration of Hg(II) was 200.0 mg/L. The adsorption isothermal and kinetic data were well fitted by the Langmuir equation and the pseudo-first-order rate equation, respectively. The adsorption mechanism of BTICF to Hg(II) was proved to follow a chelating reaction. The BTICF can be easily regenerated with 0.1M lactic acid after adsorption process and recycled at least 4 times without the loss of adsorption capacity. These facts indicate that BTICF can be used as a low-cost adsorbent for effective removal of Hg(II) from aqueous solutions.

  5. Multiphoton microscopy study of the morphological and quantity changes of collagen and elastic fiber components in keloid disease

    Science.gov (United States)

    Chen, Jianxin; Zhuo, Shuangmu; Jiang, Xingshan; Zhu, Xiaoqin; Zheng, Liqin; Xie, Shusen; Lin, Bifang; Zeng, Haishan

    2011-05-01

    Multiphoton microscopy was used to study the extracellular matrix of keloid at the molecular level without tissue fixation and staining. Direct imaging of collagen and elastin was achieved by second harmonic generation and two-photon excited fluorescence, respectively. The morphology and quantity of collagen and elastin in keloid were characterized and quantitatively analyzed in comparison to normal skin. The study demonstrated that in keloid, collagen content increased in both the upper dermis and the deep dermis, while elastin mostly showed up in the deep dermis and its quantity is higher compared to normal skin. This suggests the possibility that abnormal fibroblasts synthesized an excessive amount of collagen and elastin at the beginning of keloid formation, corresponding to the observed deep dermis, while after a certain time point, the abnormal fibroblast produced mostly collagen, corresponding to the observed upper dermis. The morphology of collagen and elastin in keloid was disrupted and presented different variations. In the deep dermis, elastic fibers showed node structure, while collagen showed obviously regular gaps between adjacent bundles. In the upper dermis, collagen bundles aligned in a preferred direction, while elastin showed as sparse irregular granules. This new molecular information provided fresh insight about the development process of keloid.

  6. Antibacterial activity of silver nanoparticles stabilized on tannin-grafted collagen fiber

    Energy Technology Data Exchange (ETDEWEB)

    He Li [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Gao Siying; Wu Hao [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); Liao Xuepin, E-mail: xpliao@scu.edu.cn [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); He Qiang [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Shi Bi, E-mail: sibitannin@vip.163.com [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China) and Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China)

    2012-07-01

    Bayberry tannin (BT), a typical plant polyphenol, was grafted on collagen fiber (CF) in different mass ratios. Subsequently, the BT-grafted CF (BT-CF) was used as carrier and stabilizer to prepare BT-CF stabilized silver nanoparticles (BT-CF-AgNPs). Scanning Electron Microscopy image of BT-CF-AgNPs showed that the BT-CF-AgNPs was in ordered fibrous state. X-ray Diffraction patterns and Transmission Electron Microscopy images offered evidence that the Ag nanoparticles were well dispersed on BT-CF. Fourier Transform-Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) investigations revealed that the Ag NPs were stabilized by the phenolic hydroxyls and quinones of BT on CF through electron donation/acception interaction. Antibacterial experiments demonstrated that BT-CF-AgNPs exhibited high antibacterial activity. When cell suspensions of Escherichia coli and Staphylococcus aureus (10{sup 4}-10{sup 5} cfu/mL) were contacted with BT{sub 0.19}-CF-AgNPs (mass ratio of BT to CF = 0.19, conc. of Ag = 8 {mu}g/mL) at 310 K under constant shaking, the number of cells went down to zero within 2 h. In addition, the minimal inhibitory concentration of BT{sub 0.19}-CF-AgNPs against Escherichia coli, Staphylococcus aureus, Penicillium glaucum and Saccharomyces cerevisiae was 2 {mu}g/mL, 4 {mu}g/mL, 6 {mu}g/mL and 12 {mu}g/mL Ag, respectively. During recycling use, the antibacterial activity of BT{sub 0.19}-CF-AgNPs against Escherichia coli can last for 5 cycles. These facts suggest that BT-CF-AgNPs can be used as a new and effective antibacterial agent. - Highlights: Black-Right-Pointing-Pointer Bayberry tannin-grafted collagen fiber can be acted as carrier and stabilizer for the preparation of nano-silver (AgNPs) with different particle size. Black-Right-Pointing-Pointer Bayberry tannin-grafted collagen fiber stabilized silver nanoparticles (BT-CF-AgNPs) were characterized by SEM, XRD, TEM, FTIR and XPS. Black-Right-Pointing-Pointer BT-CF-AgNPs has the

  7. Alignment of collagen fiber in knitted silk scaffold for functional massive rotator cuff repair.

    Science.gov (United States)

    Zheng, Zefeng; Ran, Jisheng; Chen, Weishan; Hu, Yejun; Zhu, Ting; Chen, Xiao; Yin, Zi; Heng, Boon Chin; Feng, Gang; Le, Huihui; Tang, Chenqi; Huang, Jiayun; Chen, Yangwu; Zhou, Yiting; Dominique, Pioletti; Shen, Weiliang; Ouyang, Hong-Wei

    2017-03-15

    Rotator cuff tear is one of the most common types of shoulder injuries, often resulting in pain and physical debilitation. Allogeneic tendon-derived decellularized matrices do not have appropriate pore size and porosity to facilitate cell infiltration, while commercially-available synthetic scaffolds are often inadequate at inducing tenogenic differentiation. The aim of this study is to develop an advanced 3D aligned collagen/silk scaffold (ACS) and investigate its efficacy in a rabbit massive rotator cuff tear model. ACS has similar 3D alignment of collagen fibers as natural tendon with superior mechanical characteristics. Based on ectopic transplantation studies, the optimal collagen concentration (10mg/ml), pore diameter (108.43±7.25μm) and porosity (97.94±0.08%) required for sustaining a stable macro-structure conducive for cellular infiltration was determined. Within in vitro culture, tendon stem/progenitor cells (TSPCs) displayed spindle-shaped morphology, and were well-aligned on ACS as early as 24h. TSPCs formed intercellular contacts and deposited extracellular matrix after 7days. With the in vivo rotator cuff repair model, the regenerative tendon of the ACS group displayed more conspicuous native microstructures with larger diameter collagen fibrils (48.72±3.75 vs. 44.26±5.03nm) that had better alignment and mechanical properties (139.85±49.36vs. 99.09±33.98N) at 12weeks post-implantation. In conclusion, these findings demonstrate the positive efficacy of the macroporous 3D aligned scaffold in facilitating rotator cuff tendon regeneration, and its practical applications for rotator cuff tendon tissue engineering. Massive rotator cuff tear is one of the most common shoulder injuries, and poses a formidable clinical challenge to the orthopedic surgeon. Tissue engineering of tendon can potentially overcome the problem. However, more efficacious scaffolds with good biocompatibility, appropriate pore size, favorable inductivity and sufficient mechanical

  8. 胶原纤维与OSAHS的相关性研究%Study of Correlation between Collagen Fiber and OSAHS

    Institute of Scientific and Technical Information of China (English)

    朱玉楠; 马瑞霞; 杨敬

    2015-01-01

    目的:探讨阻塞性睡眠呼吸暂停低通气综合征发病过程中胶原纤维的形态学改变以及Ⅰ、Ⅲ型胶原纤维面积和总的胶原纤维面积与OSAHS患者各项临床指标的相关性。方法:回顾性分析成年男性8例非鼾症和14例鼾症组的一般情况,比较组织标本形态学染色,并测量Ⅰ、Ⅲ型胶原纤维面积和总的胶原纤维的面积。结果:通过实验我们发现OSAHS患者的软腭和悬雍垂结缔组织中的胶原纤维排列不规则,而且胶原纤维的面积和Ⅰ、Ⅲ型胶原纤维面积的增多,胶原纤维面积和Ⅰ、Ⅲ型胶原纤维面积与平均血氧饱和度、AHI、呼吸暂停指数存在相关性。结论:胶原纤维改变可能与OSAHS患者口咽弹性的降低相关。%Objective:This study focuses in the OSAHS pathogenesis of morphological changes and the area of typeⅠ,Ⅲcolla-gen and the total area of collagen fibers in patients with OSAHS of the clinical parameters .Methods:Retrospective analysis of OS-AHS and non OSAHS adult,To analysis of general condition,measure the area of collagen fiber and type Ⅰ, Ⅲcollagen fiber.Re-sults:In this study, we found that the connective tissue of soft palate and uvula of patients with OSAHS is irregular arrangement of collagen fibers, and the area of collagen fiber and typeⅠ,Ⅲcollagen fiber increased.The area of them is associated with the aver-age oxygen saturation, AHI and apnea index.Conclusion:Collagen fibers change may be associated with OSAHS patients of lower the oropharyngeal elasticity.

  9. Influence of hyperprolactinemia on collagen fibers in the lacrimal gland of female mice

    Directory of Open Access Journals (Sweden)

    Ariadne Stavare Leal Araujo

    2015-09-01

    Full Text Available OBJECTIVE: To quantify the collagen fibers in the lacrimal gland of female mice with hyperprolactinemia. METHODS: Forty adult female mice were randomly divided into two groups with 20 animals each: nonpregnant control (CTR1, control group, 0.2 mL of saline solution and nonpregnant experimental (HPRL1, experimental group, 200 µg/day metoclopramide. Treatments lasted for 50 consecutive days. On day 50, 10 females from each group (control and experimental were euthanized in the proestrus phase; then, the blood was collected and the lacrimal glands were removed. Thereafter, the remaining females were placed with the mates and continued to receive treatment with saline solution or metoclopramide. On the 6th post-coital day, 10 pregnant females from the control group (CTR2 and 10 pregnant females from the experimental group (HPRL2 were euthanized, after which blood was collected and the lacrimal glands removed. The lacrimal glands were processed for morphological analyses and collagen quantification, and prolactin and sex steroid levels were measured in the blood samples. Data were statistically analyzed using an unpaired Student t test (p<0.05. RESULTS: Morphological analysis revealed greater structural tissue disorganization of the lacrimal glands in the metoclopramide-treated groups. The total collagen content was significantly higher in the HPRL1 group than in the CTR1 group (p<0.05, whereas the difference between the CTR2 and HPRL2 groups was not significant. CONCLUSION: Our data suggest an impairment in the functioning of the lacrimal gland as a consequence of increased prolactin levels and decreased serum levels of estrogen and progesterone.

  10. Influence of hyperprolactinemia on collagen fibers in the lacrimal gland of female mice.

    Science.gov (United States)

    Araujo, Ariadne Stavare Leal; Simões, Manuel de Jesus; Verna, Carina; Simões, Ricardo Santos; Soares Júnior, José Maria; Baracat, Edmund Chada; Gomes, Regina Célia Teixeira

    2015-09-01

    To quantify the collagen fibers in the lacrimal gland of female mice with hyperprolactinemia. Forty adult female mice were randomly divided into two groups with 20 animals each: nonpregnant control (CTR1, control group, 0.2 mL of saline solution) and nonpregnant experimental (HPRL1, experimental group, 200 µg/day metoclopramide). Treatments lasted for 50 consecutive days. On day 50, 10 females from each group (control and experimental) were euthanized in the proestrus phase; then, the blood was collected and the lacrimal glands were removed. Thereafter, the remaining females were placed with the mates and continued to receive treatment with saline solution or metoclopramide. On the 6th post-coital day, 10 pregnant females from the control group (CTR2) and 10 pregnant females from the experimental group (HPRL2) were euthanized, after which blood was collected and the lacrimal glands removed. The lacrimal glands were processed for morphological analyses and collagen quantification, and prolactin and sex steroid levels were measured in the blood samples. Data were statistically analyzed using an unpaired Student t test (p<0.05). Morphological analysis revealed greater structural tissue disorganization of the lacrimal glands in the metoclopramide-treated groups. The total collagen content was significantly higher in the HPRL1 group than in the CTR1 group (p<0.05), whereas the difference between the CTR2 and HPRL2 groups was not significant. Our data suggest an impairment in the functioning of the lacrimal gland as a consequence of increased prolactin levels and decreased serum levels of estrogen and progesterone.

  11. Impact of elastin incorporation into electrochemically aligned collagen fibers on mechanical properties and smooth muscle cell phenotype.

    Science.gov (United States)

    Nguyen, Thuy-Uyen; Bashur, Chris A; Kishore, Vipuil

    2016-03-17

    Application of tissue-engineered vascular grafts (TEVGs) for the replacement of small-diameter arteries is limited due to thrombosis and intimal hyperplasia. Previous studies have attempted to address the limitations of TEVGs by developing scaffolds that mimic the composition (collagen and elastin) of native arteries to better match the mechanical properties of the graft with the native tissue. However, most existing scaffolds do not recapitulate the aligned topography of the collagen fibers found in native vessels. In the current study, based on the principles of isoelectric focusing, two different types of elastin (soluble and insoluble) were incorporated into highly oriented electrochemically aligned collagen (ELAC) fibers and the effect of elastin incorporation on the mechanical properties of the ELAC fibers and smooth muscle cell (SMC) phenotype was investigated. The results indicate that elastin incorporation significantly decreased the modulus of ELAC fibers to converge upon that of native vessels. Further, a significant increase in yield strain and decrease in Young's modulus was observed on all fibers post SMC culture compared with before the culture. Real-time polymerase chain reaction results showed a significant increase in the expression of α-smooth muscle actin and calponin on ELAC fibers with insoluble elastin, suggesting that incorporation of insoluble elastin induces a contractile phenotype in SMCs after two weeks of culture on ELAC fibers. Immunofluorescence results showed that calponin expression increased with time on all fibers. In conclusion, insoluble elastin incorporated ELAC fibers have the potential to be used for the development of functional TEVGs for the repair and replacement of small-diameter arteries.

  12. Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces.

    Science.gov (United States)

    Adams, K; Schulz-Kornas, E; Arzi, B; Failing, K; Vogelsberg, J; Staszyk, C

    2016-11-01

    In the last decade, the equine masticatory apparatus has received much attention. Numerous studies have emphasized the importance of the temporomandibular joint (TMJ) in the functional process of mastication. However, ultrastructural and histological data providing a basis for biomechanical and histopathological considerations are not available. The aim of the present study was to analyze the architecture of the collagen fiber apparatus in the articular surfaces of the equine TMJ to reveal typical morphological features indicating biomechanical adaptions. Therefore, the collagen fiber alignment was visualized using the split-line technique in 16 adult warmblood horses without any history of TMJ disorders. Within the central two-thirds of the articular surfaces of the articular tubercle, the articular disc and the mandibular head, split-lines ran in a correspondent rostrocaudal direction. In the lateral and medial aspects of these articular surfaces, the split-line pattern varied, displaying curved arrangements in the articular disc and punctual split-lines in the bony components. Mediolateral orientated split-lines were found in the rostral and caudal border of the articular disc and in the mandibular fossa. The complex movements during the equine chewing cycle are likely assigned to different areas of the TMJ. The split-line pattern of the equine TMJ is indicative of a relative movement of the joint components in a preferential rostrocaudal direction which is consigned to the central aspects of the TMJ. The lateral and medial aspects of the articular surfaces provide split-line patterns that indicate movements particularly around a dorsoventral axis.

  13. Electrospun Collagen/Silk Tissue Engineering Scaffolds: Fiber Fabrication, Post-Treatment Optimization, and Application in Neural Differentiation of Stem Cells

    Science.gov (United States)

    Zhu, Bofan

    Biocompatible scaffolds mimicking the locally aligned fibrous structure of native extracellular matrix (ECM) are in high demand in tissue engineering. In this thesis research, unidirectionally aligned fibers were generated via a home-built electrospinning system. Collagen type I, as a major ECM component, was chosen in this study due to its support of cell proliferation and promotion of neuroectodermal commitment in stem cell differentiation. Synthetic dragline silk proteins, as biopolymers with remarkable tensile strength and superior elasticity, were also used as a model material. Good alignment, controllable fiber size and morphology, as well as a desirable deposition density of fibers were achieved via the optimization of solution and electrospinning parameters. The incorporation of silk proteins into collagen was found to significantly enhance mechanical properties and stability of electrospun fibers. Glutaraldehyde (GA) vapor post-treatment was demonstrated as a simple and effective way to tune the properties of collagen/silk fibers without changing their chemical composition. With 6-12 hours GA treatment, electrospun collagen/silk fibers were not only biocompatible, but could also effectively induce the polarization and neural commitment of stem cells, which were optimized on collagen rich fibers due to the unique combination of biochemical and biophysical cues imposed to cells. Taken together, electrospun collagen rich composite fibers are mechanically strong, stable and provide excellent cell adhesion. The unidirectionally aligned fibers can accelerate neural differentiation of stem cells, representing a promising therapy for neural tissue degenerative diseases and nerve injuries.

  14. Greener synthesis of electrospun collagen/hydroxyapatite composite fibers with an excellent microstructure for bone tissue engineering

    Directory of Open Access Journals (Sweden)

    Zhou YY

    2015-04-01

    Full Text Available Yuanyuan Zhou,1,2 Hongchang Yao,1 Jianshe Wang,1 Dalu Wang,1 Qian Liu,1 Zhongjun Li11College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, People’s Republic of China; 2Institute of Enviromental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, People’s Republic of ChinaAbstract: In bone tissue engineering, collagen/hydroxyapatite (HAP fibrous composite obtained via electrospinning method has been demonstrated to support the cells’ adhesion and bone regeneration. However, electrospinning of natural collagen often requires the use of cytotoxic organic solvents, and the HAP crystals were usually aggregated and randomly distributed within a fibrous matrix of collagen, limiting their clinical potential. Here, an effective and greener method for the preparation of collagen/HAP composite fibers was developed for the first time, and this green product not only had 40 times higher mechanical properties than that previously reported, but also had an excellent microstructure similar to that of natural bone. By dissolving type I collagen in environmentally friendly phosphate buffered saline/ethanol solution instead of the frequently-used cytotoxic organic solvents, followed with the key step of desalination, co-electrospinning the collagen solution with the HAP sol, generates a collagen/HAP composite with a uniform and continuous fibrous morphology. Interestingly, the nano-HAP needles were found to preferentially orient along the longitudinal direction of the collagen fibers, which mimicked the nanostructure of natural bones. Based on the characterization of the related products, the formation mechanism for this novel phenomenon was proposed. After cross-linking with 1-ethyl-3-(3-dimethyl-aminopropyl-1-carbodiimide hydrochloride/N-hydroxysuccinimide, the obtained composite exhibited a significant enhancement in mechanical properties. In addition, the biocompatibility of the

  15. Preparation of a biomimetic composite scaffold from gelatin/collagen and bioactive glass fibers for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi, Esmaeel; Azami, Mahmoud [Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Kajbafzadeh, Abdol-Mohammad [Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Pediatric Urology Research Center, Section of Tissue Engineering and Stem Cells Therapy, Department of Pediatric Urology, Children' s Hospital Medical Center, Tehran, Iran (IRI) (Iran, Islamic Republic of); Moztarzadeh, Fatollah [Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); Faridi-Majidi, Reza [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shamousi, Atefeh; Karimi, Roya [Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ai, Jafar, E-mail: jafar_ai@tums.ac.ir [Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Brain and Spinal Injury Research Center (BASIR), Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2016-02-01

    Bone tissue is a composite material made of organic and inorganic components. Bone tissue engineering requires scaffolds that mimic bone nature in chemical and mechanical properties. This study proposes a novel method for preparing composite scaffolds that uses sub-micron bioglass fibers as the organic phase and gelatin/collagen as the inorganic phase. The scaffolds were constructed by using freeze drying and electro spinning methods and their mechanical properties were enhanced by using genipin crosslinking agent. Electron microscopy micrographs showed that the structure of composite scaffolds were porous with pore diameters of approximately 70–200 μm, this was again confirmed by mercury porosimetery. These pores are suitable for osteoblast growth. The diameters of the fibers were approximately 150–450 nm. Structural analysis confirmed the formation of desirable phases of sub-micron bioglass fibers. Cellular biocompatibility tests illustrated that scaffolds containing copper ion in the bioglass structure had more cell growth and osteoblast attachment in comparison to copper-free scaffolds. - Highlights: • Fabrication of 45S5 sub-micron bioglass fiber using electrospinning method. • Production of copper doped submicron bioglass fibers on 45S5 bioglass base by electrospinning sol gel route method. • Incorporation of bioglass/Cu-bioglass sub-micron fibers into gelatin/collagen matrix to form biomimetic composite scaffold which were non-cytotoxic according to MTT assay. • Discovering that copper can decrease the glass transition temperatures and enhance osteoblast cell adhesion and viability.

  16. Mechanical implications of the domain structure of fiber-forming collagens: comparison of the molecular and fibrillar flexibilities of the alpha1-chains found in types I-III collagen.

    Science.gov (United States)

    Silver, Frederick H; Horvath, Istvan; Foran, David J

    2002-05-21

    Fibrillar collagens store, transmit and dissipate elastic energy during tensile deformation. Results of previous studies suggest that the collagen molecule is made up of alternating rigid and flexible domains, and extension of the flexible domains is associated with elastic energy storage. In this study, we model the flexibility of the alpha1-chains found in types I-III collagen molecules and microfibrils in order to understand the molecular basis of elastic energy storage in collagen fibers by analysing the areas under conformational plots for dipeptide sequences. Results of stereochemical modeling suggest that the collagen triple helix is made up of rigid and flexible domains that alternate with periods that are multiples of three amino acid residues. The relative flexibility of dipeptide sequences found in the flexible regions is about a factor of five higher than that found for the flexibility of the rigid regions, and the flexibility of types II and III collagen molecules appears to be higher than that found for the type I collagen molecule. The different collagen alpha1-chains were compared by correlating the flexibilities. The results suggest that the flexibilities of the alpha1-chains of types I and III collagen are more closely related than the flexibilities of the alpha1-chains in types I and II and II and III collagen. The flexible domains found in the alpha1-chains of types I-III collagen were found to be conserved in the microfibril and had periods of about 15 amino acid residues and multiples thereof. The flexibility profiles of types I and II collagen microfibrils were found to be more highly correlated than those for types I and III and II and III. These results suggest that the domain structure of the alpha1-chains found in types I-III collagen is an efficient means for storage of elastic energy during stretching while preserving the triple helical structure of the overall molecule. It is proposed that all collagens that form fibers are designed to

  17. Quantification of collagen fiber organization in biological tissues at cellular and molecular scales using second-harmonic generation imaging

    Science.gov (United States)

    Ambekar Ramachandra Rao, Raghu

    Collagen is the most abundant structural protein found in the human body, and is responsible for providing structure and function to tissues. Collagen molecules organize naturally into structures called fibers on the scale of the wavelength of light and lack inversion symmetry, thus allowing for the process of second harmonic generation (SHG) when exposed to intense incident light. We have developed two quantitative techniques: Fourier transform-second-harmonic generation (FT-SHG) imaging and generalized chi2 second-harmonic generation (chi2-SHG) imaging. In order to show that FT-SHG imaging can be used as a valuable diagnostic tool for real-world biological problems, we first investigate collagenase-induced injury in horse tendons. Clear differences in collagen fiber organization between normal and injured tendon are quantified. In particular, we observe that the regularly oriented organization of collagen fibers in normal tendons is disrupted in injured tendons leading to a more random organization. We also observe that FT-SHG microscopy is more sensitive in assessing tendon injury compared to the conventional polarized light microscopy. The second study includes quantifying collagen fibers in cortical bone using FT-SHG imaging and comparing it with scanning electron microscopy (SEM). Further, as an example study, we show how FT-SHG imaging could be used to quantify changes in bone structure as a function of age. Some initial work and future directions for extending FT-SHG to 3D are also discussed. The second technique, chi2-SHG imaging, takes advantage of the coherent nature of SHG and utilizes polarization to extract the second-order susceptibility (d elements) which provides information on molecular organization, i.e., it provides access to sub-diffractional changes "optically". We use chi2-SHG in combination with FT-SHG imaging to investigate a couple of biological problems. First, we quantify differences in collagen fiber organization between cornea and

  18. Collagen mimetic peptide discs promote assembly of a broad range of natural protein fibers through hydrophobic interactions.

    Science.gov (United States)

    McGuinness, Kenneth; Nanda, Vikas

    2017-07-19

    Collagen mimetic peptides that alone formed two-dimensional nanoscale discs driven by hydrophobic interactions were shown in electron microscopy studies to also co-assemble with natural fibrous proteins to produce discs-on-a-string (DoS) nanostructures. In most cases, peptide discs also facilitated bundling of the protein fibers. This provides insight into how synthetic and natural proteins may be combined to develop multicomponent, multi-dimensional architectures at the nanoscale.

  19. Characterization of collagen fibers by means of texture analysis of second harmonic generation images using orientation-dependent gray level co-occurrence matrix method.

    Science.gov (United States)

    Hu, Wenyan; Li, Hui; Wang, Chunyou; Gou, Shanmiao; Fu, Ling

    2012-02-01

    Collagen is the most prominent protein in the human body, making up 30% of the total protein content. Quantitative studies have shown structural differences between collagen fibers of the normal and diseased tissues, due to the remodeling of the extracellular matrix during the pathological process. The dominant orientation, which is an important characteristic of collagen fibers, has not been taken into consideration for quantitative collagen analysis. Based on the conventional gray level co-occurrence matrix (GLCM) method, the authors proposed the orientation-dependent GLCM (OD-GLCM) method by estimating the dominant orientation of collagen fibers. The authors validated the utility of the OD-GLCM method on second harmonic generation (SHG) microscopic images of tendons from rats with different ages. Compared with conventional GLCM method, the authors' method has not only improved the discrimination between different tissues but also provided additional texture information of the orderliness of collagen fibers and the fiber size. The OD-GLCM method was further applied to the differentiation of the preliminary SHG images of normal and cancerous human pancreatic tissues. The combination of SHG microscopy and the OD-GLCM method might be helpful for the evaluation of diseases marked with abnormal collagen morphology.

  20. Characterization of collagen fibers by means of texture analysis of second harmonic generation images using orientation-dependent gray level co-occurrence matrix method

    Science.gov (United States)

    Hu, Wenyan; Li, Hui; Wang, Chunyou; Gou, Shanmiao; Fu, Ling

    2012-02-01

    Collagen is the most prominent protein in the human body, making up 30% of the total protein content. Quantitative studies have shown structural differences between collagen fibers of the normal and diseased tissues, due to the remodeling of the extracellular matrix during the pathological process. The dominant orientation, which is an important characteristic of collagen fibers, has not been taken into consideration for quantitative collagen analysis. Based on the conventional gray level co-occurrence matrix (GLCM) method, the authors proposed the orientation-dependent GLCM (OD-GLCM) method by estimating the dominant orientation of collagen fibers. The authors validated the utility of the OD-GLCM method on second harmonic generation (SHG) microscopic images of tendons from rats with different ages. Compared with conventional GLCM method, the authors' method has not only improved the discrimination between different tissues but also provided additional texture information of the orderliness of collagen fibers and the fiber size. The OD-GLCM method was further applied to the differentiation of the preliminary SHG images of normal and cancerous human pancreatic tissues. The combination of SHG microscopy and the OD-GLCM method might be helpful for the evaluation of diseases marked with abnormal collagen morphology.

  1. The effects of replacing collagen fibers with carbon nanotubes on the rate of bone remodeling process.

    Science.gov (United States)

    Jamilpour, Nima; Fereidoon, Abdolhosein; Rouhi, Gholamreza

    2011-08-01

    Application of carbon nanotubes (CNTs) instead of collagen fibers (CFs) in bone tissue is one of the proposed avenues for the enhancement of bone's mechanical properties. The mechanical behavior improvement caused by such a replacement is somehow guaranteed because of the superior mechanical properties of CNTs compared to those of CFs. But on the other side, bone is a very active and dynamic tissue, which is maintained through a lifelong coupled process of resorption and formation in order to reach an optimal configuration. Hence, the well accepted fact of the bone remodeling dependency on mechanical stimuli besides the differences in mechanical behavior of CNTs and CFs under loading can encourage one to hypothesize that such a replacement would cause an imbalance in the normal rate of bone remodeling process. Results of our finite element analysis indicate that the application of CNTs instead of CFs can cause a significant reduction in strain energy density, assumed here as the mechanical stimulus to initiate the bone remodeling process. Our results also show that this replacement may change the strain energy distribution within the bone. Based on a semi-mechanistic bone remodeling theory, it is speculated that this alteration in strain energy distribution in artificial bone can destabilize normal bone remodeling process, and therefore it is likely to cause some abnormalities in bone's mechanical and biological functions.

  2. Fluid-structure interaction model of aortic valve with porcine-specific collagen fiber alignment in the cusps.

    Science.gov (United States)

    Marom, Gil; Peleg, Mor; Halevi, Rotem; Rosenfeld, Moshe; Raanani, Ehud; Hamdan, Ashraf; Haj-Ali, Rami

    2013-10-01

    Native aortic valve cusps are composed of collagen fibers embedded in their layers. Each valve cusp has its own distinctive fiber alignment with varying orientations and sizes of its fiber bundles. However, prior mechanical behavior models have not been able to account for the valve-specific collagen fiber networks (CFN) or for their differences between the cusps. This study investigates the influence of this asymmetry on the hemodynamics by employing two fully coupled fluid-structure interaction (FSI) models, one with asymmetric-mapped CFN from measurements of porcine valve and the other with simplified-symmetric CFN. The FSI models are based on coupled structural and fluid dynamic solvers. The partitioned solver has nonconformal meshes and the flow is modeled by employing the Eulerian approach. The collagen in the CFNs, the surrounding elastin matrix, and the aortic sinus tissues have hyperelastic mechanical behavior. The coaptation is modeled with a master-slave contact algorithm. A full cardiac cycle is simulated by imposing the same physiological blood pressure at the upstream and downstream boundaries for both models. The mapped case showed highly asymmetric valve kinematics and hemodynamics even though there were only small differences between the opening areas and cardiac outputs of the two cases. The regions with a less dense fiber network are more prone to damage since they are subjected to higher principal stress in the tissues and a higher level of flow shear stress. This asymmetric flow leeward of the valve might damage not only the valve itself but also the ascending aorta.

  3. Scanning electron microscopy of collagen fiber orientation in the bone lamellar system in non-decalcified human samples.

    Science.gov (United States)

    Pannarale, L; Braidotti, P; d'Alba, L; Gaudio, E

    1994-01-01

    Previous studies on collagen fiber orientation have led to different interpretations and theories about the fiber arrangement in the lamellar compact bone. The purpose of this investigation was to provide new and more in-depth data on fiber arrangement in the lamellar bone system in order to explain the orientation of the fiber bundles. This was carried out by applying a simple method of preparation which permitted observation of non-decalcified samples. A previously isolated Haversian system was subjected to slow bending up to reaching the fracture point. Hence, the fracture surface was observed by SEM. The same samples were also observed by polarized light microscopy. A significant alternation of fiber orientation in the adjacent lamellae was observed. Different domains of differently oriented fibers were present within the same lamella; conjugating fibers connecting adjacent lamellae were also shown. This method avoided most of the artifacts due to chemical treatment of bone samples. The results can be easily interpreted by means of the same criteria applied in mechanics for the studying of composite materials.

  4. Analysis of Native-Like Ions Using Structures for Lossless Ion Manipulations.

    Science.gov (United States)

    Allen, Samuel J; Eaton, Rachel M; Bush, Matthew F

    2016-09-20

    Ion mobility separation of native-like protein and protein complex ions expands the structural information available through native mass spectrometry analysis. Here, we implement Structures for Lossless Ion Manipulations (SLIM) for the analysis of native-like ions. SLIM has been shown previously to operate with near lossless transmission of ions up to 3000 Da in mass. Here for the first time, SLIM was used to separate native-like protein and protein complex ions ranging in mass from 12 to 145 kDa. The resulting arrival-time distributions were monomodal and were used to determine collision cross section values that are within 3% of those determined from radio-frequency-confining drift cell measurements. These results are consistent with the retention of native-like ion structures throughout these experiments. The apparent resolving powers of native-like ions measured using SLIM are as high as 42, which is the highest value reported directly from experimental data for the native-like ion of a protein complex. Interestingly, the apparent resolving power depends strongly on the identity of the analyte, suggesting that the arrival-time distributions of these ions may have contributions from an ensemble of structures in the gas phase that is unique to each analyte. These results suggest that the broad range of emerging SLIM technologies may all be adaptable to the analysis of native-like ions, which will enable future applications in the areas of structural biology, biophysics, and biopharmaceutical characterization.

  5. Early adhesive behavior of bone-marrow-derived mesenchymal stem cells on collagen electrospun fibers

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Casey K; Liao, Susan; Lareu, Ricky R; Raghunath, Michael [Division of Bioengineering, National University of Singapore, 7 Engineering Drive 1, Singapore 117574 (Singapore); Li, Bojun; Ramakrishna, S [Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Larrick, James W, E-mail: doschanc@nus.edu.s [Panorama Research Institute, 2462 Wyandotte Street, Mountain View, CA 94043 (United States)

    2009-06-15

    A bioabsorbable nanofibrous scaffold was developed for early adhesion of mesenchymal stem cells (MSCs). Collagen nanofibers with diameters of 430 +- 170 nm were fabricated by electrospinning. Over 45% of the MSC population adhered to this collagen nanofiber after 30 min at room temperature. Remarkably, collagen-coated P(LLA-CL) electrospun nanofibers were almost as efficient as collagen nanofibers whereas collagen cast film did not enhance early capture when it was applied on cover slips. The adhesive efficiency could be further increased to over 20% at 20 min and over 55% at 30 min when collagen nanofibers were grafted with monoclonal antibodies recognizing CD29 or CD49a. These data demonstrate that the early adhesive behavior is highly dependent on both the surface texture and the surface chemistry of the substrate. These findings have potential applications for early capture of MSCs in an ex vivo setting under time constraints such as in a surgical setting.

  6. Dexamethasone normalizes aberrant elastic fiber production and collagen 1 secretion by Loeys-Dietz syndrome fibroblasts: a possible treatment?

    Science.gov (United States)

    Barnett, Christopher P; Chitayat, David; Bradley, Timothy J; Wang, Yanting; Hinek, Aleksander

    2011-06-01

    Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder characterized by facial dysmorphism, cleft palate, dilation of the aortic arch, blood vessel tortuosity and a high risk of aortic dissection. It is caused by mutations in the transforming growth factor β-receptor 1 and 2 (TGFβ-R1 and TGFβ-R2) genes. Fibroblasts derived from 12 Loeys-Dietz syndrome patients, six with TGFB-R1 mutations and six with TGFB-R2 mutations, were analyzed using RT-PCR, biochemical assays, immunohistochemistry and electron microscopy for production of elastin, fibrillin 1, fibulin 1 and fibulin 4 and deposition of collagen type I. All LDS fibroblasts with TGFβ-R1 mutations demonstrated decreased expression of elastin and fibulin 1 genes and impaired deposition of elastic fibers. In contrast, fibroblasts with TGFβ-R2 mutations consistently demonstrated intracellular accumulation of collagen type I in the presence of otherwise normal elastic fiber production. Treatment of the cell cultures with dexamethasone induced remarkable upregulation in the expression of tropoelastin, fibulin 1- and fibulin 4-encoding mRNAs, leading to normalization of elastic fiber production in fibroblasts with TGFβ-R1 mutations. Treatment with dexamethasone also corrected the abnormal secretion of collagen type I from fibroblasts with TGFβ-R2 gene mutations. As the organogenesis-relevant elastic fiber production occurs exclusively in late fetal and early neonatal life, these findings may have implications for treatment in early life. Further studies are required to determine if dexamethasone treatment of fetuses prenatally diagnosed with LDS would prevent or alleviate the connective tissue and vascular defects seen in this syndrome.

  7. Transcriptional regulation of acetylcholinesterase-associated collagen ColQ in fast- and slow-twitch muscle fibers.

    Science.gov (United States)

    Ting, Annie K L; Siow, Nina L; Kong, L W; Tsim, Karl W K

    2005-12-15

    The presence of a collagenous protein (ColQ) characterizes the collagen-tailed forms of acetylcholinesterase (AChE) and butyrylcholinesterase at vertebrate neuromuscular junctions, which is tethered in the synaptic basal lamina. ColQ subunits, differing mostly by their signal sequences, are encoded by transcripts ColQ-1 and ColQ-1a, which are differentially expressed in slow- and fast-twitch muscles in mammals, respectively. Both ColQ transcripts are derived from a single COLQ gene. Transcripts encoding ColQ increased during myogenic differentiation of C2C12 cells; the increase was in parallel with AChE catalytic subunit. Quantitative PCR analysis indicated that the increase during the myotube formation was due to the up regulation of ColQ-1 transcript instead of ColQ-1a. In order to reveal the regulatory mechanism of ColQ transcripts, two distinct promoters, pColQ-1 and pColQ-1a, were isolated from human COLQ gene. The ColQ promoters showed a muscle fiber type-specific expression pattern, and which was in line with the expression of endogenous transcript. After in vivo DNA transfection, pColQ-1 showed strong activity in slow-twitch muscle (e.g. soleus), while pColQ-1a was preferably expressed in fast-twitch muscle (e.g. tibialis). Mutation analysis of the ColQ promoters suggested that the muscle fiber type-specific expression pattern of ColQ transcripts was regulated by a slow upsteam regulatory element (SURE) and a fast intronic regulatory element (FIRE). These results explain the specific expression patterns of collagen-tailed AChE in slow and fast muscle fibers.

  8. In situ cross-linked electrospun fiber scaffold of collagen for fabricating cell-dense muscle tissue.

    Science.gov (United States)

    Takeda, Naoya; Tamura, Kenichi; Mineguchi, Ryo; Ishikawa, Yumiko; Haraguchi, Yuji; Shimizu, Tatsuya; Hara, Yusuke

    2016-06-01

    Engineered muscle tissues used as transplant tissues in regenerative medicine should have a three-dimensional and cell-dense structure like native tissue. For fabricating a 3D cell-dense muscle tissue from myoblasts, we proposed the electrospun type I collagen microfiber scaffold of the string-shape like a harp. The microfibers were oriented in the same direction to allow the myoblasts to align, and were strung at low density with micrometer intervals to create space for the cells to occupy. To realize this shape of the scaffold, we employed in situ cross-linking during electrospinning process for the first time to collagen fibers. The collagen microfibers in situ cross-linked with glutaraldehyde stably existed in the aqueous media and completely retained the original shape to save the spaces between the fibers for over 14 days. On the contrary, the conventional cross-linking method by exposure to a glutaraldehyde aqueous solution vapor partially dissolved and damaged the fiber to lose a low-density shape of the scaffold. Myoblasts could penetrate into the interior of the in situ cross-linked string-shaped scaffold and form the cell-dense muscle tissues. Histochemical analysis showed the total area occupied by the cells in the cross section of the tissue was approximately 73 %. Furthermore, the resulting muscle tissue fabricated from primary myoblasts showed typical sarcomeric cross-striations and the entire tissue continuously pulsated by autonomous contraction. Together with the in situ cross-linking, the string-shaped scaffold provides an efficient methodology to fabricate a cell-dense 3D muscle tissue, which could be applied in regenerative medicine in future.

  9. Quantification of collagen fibers in canine uteri treated with medroxyprogesterone acetate

    Directory of Open Access Journals (Sweden)

    Paulo Salinas

    Full Text Available ABSTRACT: Collagen plays essential roles in remodeling uterine tissue during decidualization, implantation, pregnancy and involution. To understand whether the progestational agent medroxyprogesterone acetate (MPA can modify the organization and deposit of collagen in the uteri of normal bitches (Canis Tlupus familiaris, we assessed uterine tissues by histochemistry. Uteri were grouped as: nulliparous (n=11, multiparous (n=11 and treated with MPA (n=11; nulliparous with two treatments; 5mg/kg; i.m.. The amount, location and birefringence of interstitial collagen types I and III in the fold and base of the endometrial stroma and the myometrial muscular layers were studied on sections stained with Picrosirius Red by polarized light microscopy and evaluated by ANOVA. No differences were observed in the endometrium. In the myometrium, differences were observed in collagen type I between MPA-treated and nulliparous uteri vs. multiparous (p<0.05, and differences in collagen type III between nulliparous and multiparous uteri vs. MPA-treated (p=0.0001. In conclusion, two doses of MPA had no significant effect on the investigated collagens in the extracellular matrix.

  10. Collagen fiber orientation in the femoral necks of apes and humans: do their histological structures reflect differences in locomotor loading?

    Science.gov (United States)

    Kalmey, J K; Lovejoy, C O

    2002-08-01

    Human hip joint anatomy differs substantially from that in other primates. Humans modulate pelvic tilt during walking with a highly developed abductor apparatus, but other primates (such as chimpanzees) clearly lack such an apparatus (they exhibit a Trendelenburg gait during bipedal progression). Because the primate femoral neck is cantilevered whenever it supports body mass, it must be consistently subjected to substantial bending at the neck/shaft interface during stance phase in quadrupedal or bipedal locomotion. It has been argued, however, that the powerful abduction during the single support phase in humans results in almost entirely compressive stress on the human femoral neck. We examined collagen fiber orientation in human and chimpanzee femoral neck cortices using circularly polarized light, which has been shown to be a strong correlate of bone loading patterns. Chimpanzee superior femoral neck cortex was shown to be largely nonbirefringent (dark), but the inferior cortex was strongly birefringent. Human femoral necks showed strong birefringence both superiorly and inferiorly. These results are consistent with loading patterns suggested from anatomical structure, and provide corroborative evidence of bone's ability to preferentially orient collagen fibers during extracellular matrix deposition.

  11. Characterizing the effects of aligned collagen fibers and ascorbic acid derivatives on behavior of rabbit corneal fibroblasts.

    Science.gov (United States)

    Phu, Donna; Orwin, Elizabeth J

    2009-01-01

    The cornea is responsible for functional optical activity of the mammalian eye, as it must remain transparent in order to focus light onto the retina. Corneal disease is the second leading cause worldwide of vision loss [1]. Human donor tissue transplantation in the cornea is associated with problems such as immunorejection and recurring graft failures [1]. Tissue engineering offers a promising alternative to using human donor tissues in treating corneal diseases. A viable tissue-engineered cornea must be mechanically resilient to protect the fragile intraocular components of the eye, and optically transparent to refract light onto the retina. In the native cornea, transparency is maintained by both the cells in the stromal layer and the high organization of the extracellular matrix (ECM). This study aims to combine the effects of aligned collagen fibers and ascorbic acid derivatives to control corneal fibroblast behavior to not only express the appropriate proteins, but also to deposit aligned, small diameter collagen fibers that resemble the highly organized structure of the natural ECM. Results from this study suggest that the combined effect of an aligned scaffolding material and ascorbic acid supplements can create a cell-matrix construct that both downregulates expression of the light scattering protein a-smooth muscle actin (alpha-sma) and supports an increased number of cell layers.

  12. The change of collagen fibers in the process of cutaneous photoaging%胶原纤维在皮肤光老化进程中的变化

    Institute of Scientific and Technical Information of China (English)

    郑瑞; 张嘉; 董志姗; 李灵敏; 冯艳; 白春爱

    2015-01-01

    Objective To observe the change of collagen fibers in the exposure and non-exposure skin at different ages, and to investigate the influence of UV on collagen fibers of skin. Methods Skin specimens of 30 patients (9-78y) were stained with VG staining method for collagen fibers and observed. Results Compared with adolescent, collagen fibers of middle and old aged decreased in both exposure and non-exposure skin,and exposure skin were sig-nificantly reduced. Conclusion Long-term ultraviolet radiation would reduce the content of collagen fibers, and caused the formation of skin wrinkles.%目的:观察随着年龄增长,胶原纤维在光暴露皮肤和光保护皮肤中的变化,探讨紫外线对皮肤胶原纤维的影响。方法取(9~78)岁正常皮肤标本共30例,采用VG法染色并观察结果。结果与青少年皮肤的胶原纤维染色结果相比,中老年人皮肤的光暴露和光保护部位的胶原纤维均表现为减少,但光暴露部位胶原纤维的减少更明显。结论长期紫外线照射,可能造成皮肤胶原纤维减少,从而皮肤出现皱纹、松弛的老化表现。

  13. 胶原重聚集纤维材料的制备和表征%Preparation and characterization of collagen re-assembled fibers

    Institute of Scientific and Technical Information of China (English)

    魏香奕; 张文华; 石碧

    2014-01-01

    Collagen re-assembled fibers were prepared from type Ⅰ collagen molecules via salting out-acetone de-hydration-glutaraldehyde crosslinking.Then the material was characterized by scanning electron microscopy (SEM),Fourier transform infrared spectroscopy (FT-IR),differential scanning calorimetry (DSC)and specific surface area analyzer,to obtain its morphology,thermal stability and specific surface area.The results showed that the collagen re-assembled fibers presented a fluffy fibrous appearance.SEM images revealed that the colla-gen re-assembled fibers were composed of interwoven nano fibrils (30-150 nm in diameter),at the micro-scale. The specific surface area of the material was 26 m2/g,which was more than that of natural and modified colla-gen fibers.Collagen molecules in the material still kept a natural triple helix structure.The thermal denatur-ation temperature of the material was 85 ℃.The preparation of collagen re-assembled fibers provides a prospect for further utilization of collagen resource,such as adsorption material,catalyst supported material and bioma-terial.%以Ⅰ型胶原分子为原料,采用盐析-丙酮脱水-戊二醛交联的反应路线制备了胶原重聚集纤维材料,并采用 SEM、FT-IR、DSC 及比表面孔隙分析仪对材料的微观形貌、热稳定性和比表面积等进行了表征.结果表明,胶原重聚集纤维材料外观为浅黄色蓬松纤维形态,微观尺度上由直径在30~150 nm 之间的纳米纤维交织而成;材料比表面积为26 m2/g,远大于天然胶原纤维及其改性产物的比表面积;材料中胶原分子的三股螺旋结构未被破坏;材料的热变性温度达到85℃.胶原重聚集纤维材料的制备思路,有望为胶原资源在吸附材料、催化剂载体以及生物材料等领域的应用提供参考.

  14. Complex collagen fiber and membrane morphologies of the whole porcine aortic valve.

    Directory of Open Access Journals (Sweden)

    Christopher A Rock

    Full Text Available OBJECTIVES: Replacement aortic valves endeavor to mimic native valve function at the organ, tissue, and in the case of bioprosthetic valves, the cellular levels. There is a wealth of information about valve macro and micro structure; however, there presently is limited information on the morphology of the whole valve fiber architecture. The objective of this study was to provide qualitative and quantitative analyses of whole valve and leaflet fiber bundle branching patterns using a novel imaging system. METHODS: We developed a custom automated microscope system with motor and imaging control. Whole leaflets (n = 25 were imaged at high resolution (e.g., 30,000×20,000 pixels using elliptically polarized light to enhance contrast between structures without the need for staining or other methods. Key morphologies such as fiber bundle size and branching were measured for analyses. RESULTS: The left coronary leaflet displayed large asymmetry in fiber bundle organization relative to the right coronary and non-coronary leaflets. We observed and analyzed three main patterns of fiber branching; tree-like, fan-like, and pinnate structures. High resolution images and quantitative metrics are presented such as fiber bundle sizes, positions, and branching morphological parameters. SIGNIFICANCE: To our knowledge there are currently no high resolution images of whole fresh leaflets available in the literature. The images of fiber/membrane structures and analyses presented here could be highly valuable for improving the design and development of more advanced bioprosthetic and/or bio-mimetic synthetic valve replacements.

  15. Novel genipin-collagen immobilization of polylactic acid (PLA) fibers for use as tissue engineering scaffolds.

    Science.gov (United States)

    Tambe, Nisarg; Di, Jin; Zhang, Ze; Bernacki, Susan; El-Shafei, Ahmed; King, Martin W

    2015-08-01

    The material surface plays an important role in the case of biomaterials used as tissue engineering scaffolds. On exposure to a biological environment, extra cellular matrix (ECM) proteins are adsorbed non-specifically onto the surface and cells interact indirectly with the surface through the adsorbed proteins. Most synthetic polymeric biomaterials lack the desirable surface properties for cells as well as have poor cellular adhesion due to their hydrophobic nature. The main objective of this study was to harness surface functionalization technologies to fabricate scaffolds that would be biocompatible and support the adhesion and proliferation of fibroblast cells. The collagen was immobilized on the surface of functionalized PLA via a novel natural cross-linking molecule genipin which resulted in improved cell proliferation of human dermal fibroblasts as compared to the PLA surface coated with collagen without genipin. It is believed that genipin helps reduce steric problems between the functional groups and large protein molecules, and enables immobilized peptide to move more freely in a biological environment.

  16. Extraction and Characterization of Collagen Fiber from Bovine Tendon%牛肌腱胶原纤维的提取及其性能表征

    Institute of Scientific and Technical Information of China (English)

    刘萌; 李建龙; 但年华; 但卫华

    2013-01-01

    以牛肌腱为原材料,通过酸-酶结合方法提取胶原纤维,采用氨基酸分析仪、红外、DSC、电泳、原子力显微镜等研究了其结构和性能.研究结果表明:胶原纤维的热变性温度为68.7℃,其氨基酸组成与Ⅰ型胶原相似,纤维在1239.28、1 338.67、1 404.45cm-1等处具有胶原的典型红外吸收峰,SDS-PAGE电泳中只含有α、β、γ 4条分离带,该原纤维的直径约为35 nm.%The collagen fibers were extracted from bovine tendon by acid - enzyme. The structure and performance of the collagen fibers were studied by IR, DSC electrophoresis and AFM. The results show that The denaturation temperature of collagen fibers is 68.7℃, of which the primary amino acid composition is similar to Sigma I collagen. Besides, absorption peaks of collagen are observed at 1 239. 28cm-1,1 338. 67cm-1,1 404. 45cm-1, and only four separated bands of α、β、γ are exhibited by SDS -PAGE Electrophoresis. Finally, the fiber diameter is 35nm.

  17. Imaging analysis of collagen fiber networks in cusps of porcine aortic valves: effect of their local distribution and alignment on valve functionality.

    Science.gov (United States)

    Mega, Mor; Marom, Gil; Halevi, Rotem; Hamdan, Ashraf; Bluestein, Danny; Haj-Ali, Rami

    2016-01-01

    The cusps of native aortic valve (AV) are composed of collagen bundles embedded in soft tissue, creating a heterogenic tissue with asymmetric alignment in each cusp. This study compares native collagen fiber networks (CFNs) with a goal to better understand their influence on stress distribution and valve kinematics. Images of CFNs from five porcine tricuspid AVs are analyzed and fluid-structure interaction models are generated based on them. Although the valves had similar overall kinematics, the CFNs had distinctive influence on local mechanics. The regions with dilute CFN are more prone to damage since they are subjected to higher stress magnitudes.

  18. Second language processing shows increased native-like neural responses after months of no exposure.

    Science.gov (United States)

    Morgan-Short, Kara; Finger, Ingrid; Grey, Sarah; Ullman, Michael T

    2012-01-01

    Although learning a second language (L2) as an adult is notoriously difficult, research has shown that adults can indeed attain native language-like brain processing and high proficiency levels. However, it is important to then retain what has been attained, even in the absence of continued exposure to the L2--particularly since periods of minimal or no L2 exposure are common. This event-related potential (ERP) study of an artificial language tested performance and neural processing following a substantial period of no exposure. Adults learned to speak and comprehend the artificial language to high proficiency with either explicit, classroom-like, or implicit, immersion-like training, and then underwent several months of no exposure to the language. Surprisingly, proficiency did not decrease during this delay. Instead, it remained unchanged, and there was an increase in native-like neural processing of syntax, as evidenced by several ERP changes--including earlier, more reliable, and more left-lateralized anterior negativities, and more robust P600s, in response to word-order violations. Moreover, both the explicitly and implicitly trained groups showed increased native-like ERP patterns over the delay, indicating that such changes can hold independently of L2 training type. The results demonstrate that substantial periods with no L2 exposure are not necessarily detrimental. Rather, benefits may ensue from such periods of time even when there is no L2 exposure. Interestingly, both before and after the delay the implicitly trained group showed more native-like processing than the explicitly trained group, indicating that type of training also affects the attainment of native-like processing in the brain. Overall, the findings may be largely explained by a combination of forgetting and consolidation in declarative and procedural memory, on which L2 grammar learning appears to depend. The study has a range of implications, and suggests a research program with

  19. Second language processing shows increased native-like neural responses after months of no exposure.

    Directory of Open Access Journals (Sweden)

    Kara Morgan-Short

    Full Text Available Although learning a second language (L2 as an adult is notoriously difficult, research has shown that adults can indeed attain native language-like brain processing and high proficiency levels. However, it is important to then retain what has been attained, even in the absence of continued exposure to the L2--particularly since periods of minimal or no L2 exposure are common. This event-related potential (ERP study of an artificial language tested performance and neural processing following a substantial period of no exposure. Adults learned to speak and comprehend the artificial language to high proficiency with either explicit, classroom-like, or implicit, immersion-like training, and then underwent several months of no exposure to the language. Surprisingly, proficiency did not decrease during this delay. Instead, it remained unchanged, and there was an increase in native-like neural processing of syntax, as evidenced by several ERP changes--including earlier, more reliable, and more left-lateralized anterior negativities, and more robust P600s, in response to word-order violations. Moreover, both the explicitly and implicitly trained groups showed increased native-like ERP patterns over the delay, indicating that such changes can hold independently of L2 training type. The results demonstrate that substantial periods with no L2 exposure are not necessarily detrimental. Rather, benefits may ensue from such periods of time even when there is no L2 exposure. Interestingly, both before and after the delay the implicitly trained group showed more native-like processing than the explicitly trained group, indicating that type of training also affects the attainment of native-like processing in the brain. Overall, the findings may be largely explained by a combination of forgetting and consolidation in declarative and procedural memory, on which L2 grammar learning appears to depend. The study has a range of implications, and suggests a research

  20. Segmentation and measurement of collagen fibers for shoulder and joint therapy studies

    Energy Technology Data Exchange (ETDEWEB)

    Mascio, L. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    Various shoulder instabilities are debilitating, especially in individuals who perform overhead activities. Thermal modification of soft tissues in joints may allow precise alteration of these tissues` mechanical and/or structural properties to enhance joint function without inducing cell death or an inflammatory response. Several studies have evaluated laser energy for tissue welding. The collective findings are promising, and the next step is to identify the mechanisms responsible for laser-induced capsular tissue alternation, and the short- and long-term effects of non-ablative laser energy on joint capsular tissue. One step toward this goal is to compare the effect of three laser energy densities on the histologic properties of the tissue evaluating the architecture of the collagen (including density, fibril diameter distribution, and interfibrillar space) in sheep at various time intervals after surgery. The specific computer algorithms that are being used to make these measurements will be described.

  1. The density of collagen fiber in alveolus mandibular bone of rabbit after augmentation with powder demineralized bone matrix post incisivus extraction

    Directory of Open Access Journals (Sweden)

    Regina TC. Tandelilin

    2006-06-01

    Full Text Available The bone defect due to tooth extraction contributes the most cases reported in the aspects of oral surgery. The defect can be preventively managed by adding powder bone matrix intended for augmentation which eventually induces the formation of new bones. This hard tissue wound healing is preceded by the presence of collagen fibers. The aim of this study was to determine the density of collagen fiber in the alveolus mandibular bone of rabbit which was augmented using powder demineralized bone matrix (DBM post incisivus extraction. Twenty four male rabbits aged 2.5–3 months weighed 900–1,100 grams were randomly divided into two groups. The treated rabbits were augmented with DBM after the incisivus extraction on mandible. The mucosa was then sutured. On the other hand, the controlled rabbits received similar treatments with those of the treated rabbits except there was no augmentation of DBM. Decapitation of treated and controlled rabbits was made on day 5, 7, 10, and 14 days post surgery, each with three rabbits. Mandibles were cut, decalcified, and imbedded in paraffin block. The staining was done using Mallory. Significant differences in the density of collagen were noted on day 10 and 14 post surgery, indicating that powder demineralized bone matrix successfully induced the stimulation of collagen.

  2. Altered stress fibers and integrin expression in the Malpighian epithelium of Drosophila type IV collagen mutants

    Directory of Open Access Journals (Sweden)

    András A. Kiss

    2016-06-01

    Full Text Available Basement membranes (BMs are highly specialized extracellular matrices (ECMs that provide support and polarization cues for epithelial cells. Proper adhesion to the BM is pivotal in epithelial cell function and survival. Type IV collagens are the predominant components of all types of BMs, that form an irregular, polygonal lattice and serve as a scaffold for numerous other BM components and BM-associated cells. Mutations in the ubiquitous human BM components COL4A1 and COL4A2 cause a multisystem disorder involving nephropathy. Affected patients develop renal dysfunction and chronic kidney failure with or without hematuria. Mouse Col4a1 and Col4a2 mutants recapitulate the human symptoms. In vertebrates, excretion is accomplished by the kidneys and by the Malpighian tubules in insects, including the fruit fly Drosophila. Our present results with dominant, temperature-sensitive mutation of the Drosophila col4a1 gene demonstrate altered integrin expression and amplified effects of mechanical stress on the Malpighian epithelial cytoskeleton.

  3. Second-harmonic generation microscopy used to evaluate the effect of the dimethyl sulfoxide in the cryopreservation process in collagen fibers of differentiated chondrocytes

    Science.gov (United States)

    Andreoli-Risso, M. F.; Duarte, A. S. S.; Ribeiro, T. B.; Bordeaux-Rego, P.; Luzo, A.; Baratti, M. O.; Adur, J.; de Thomaz, A. A.; Pelegati, V. B.; Carvalho, H. F.; Cesar, C. L.; Kharmadayan, P.; Costa, F. F.; Olalla-Saad, S. T.

    2012-03-01

    Cartilaginous lesions are a significant public health problem and the use of adult stem cells represents a promising therapy for this condition. Cryopreservation confers many advantages for practitioners engaged in cell-based therapies. However, conventional slow freezing has always been associated with damage and mortality due to intracellular ice formation, cryoprotectant toxicity, and dehydration. The aim of this work is to observe the effect of the usual Dimethyl Sulfoxide (DMSO) cryopreservation process on the architecture of the collagen fiber network of chondrogenic cells from mesenchymal stem cells by Second Harmonic Generation (SHG) microscopy. To perform this study we used Mesenchymal Stem Cells (MSC) derived from adipose tissue which presents the capacity to differentiate into other lineages such as osteogenic, adipogenic and chondrogenic lineages. Mesenchymal stem cells obtained after liposuction were isolated digested by collagenase type I and characterization was carried out by differentiation of mesodermic lineages, and flow cytometry using specific markers. The isolated MSCs were cryopreserved by the DMSO technique and the chondrogenic differentiation was carried out using the micromass technique. We then compared the cryopreserved vs non-cryopreserved collagen fibers which are naturally formed during the differentiation process. We observed that noncryopreserved MSCs presented a directional trend in the collagen fibers formed which was absent in the cryopreserved MSCs. We confirmed this trend quantitatively by the aspect ratio obtained by Fast Fourier Transform which was 0.76 for cryopreserved and 0.52 for non-cryopreserved MSCs, a statistical significant difference.

  4. Mechanical properties of collagen fibrils

    OpenAIRE

    Wenger, M. P. E.; Bozec, L.; Horton, M. A.; Mesquida, P

    2007-01-01

    The formation of collagen fibers from staggered subfibrils still lacks a universally accepted model. Determining the mechanical properties of single collagen fibrils ( diameter 50 - 200 nm) provides new insights into collagen structure. In this work, the reduced modulus of collagen was measured by nanoindentation using atomic force microscopy. For individual type 1 collagen fibrils from rat tail, the modulus was found to be in the range from 5 GPa to 11.5 GPa ( in air and at room temperature)...

  5. A native-like corneal construct using donor corneal stroma for tissue engineering.

    Directory of Open Access Journals (Sweden)

    Jing Lin

    Full Text Available Tissue engineering holds great promise for corneal transplantation to treat blinding diseases. This study was to explore the use of natural corneal stroma as an optimal substrate to construct a native like corneal equivalent. Human corneal epithelium was cultivated from donor limbal explants on corneal stromal discs prepared by FDA approved Horizon Epikeratome system. The morphology, phenotype, regenerative capacity and transplantation potential were evaluated by hematoxylin eosin and immunofluorescent staining, a wound healing model, and the xeno-transplantation of the corneal constructs to nude mice. An optically transparent and stratified epithelium was rapidly generated on donor corneal stromal substrate and displayed native-like morphology and structure. The cells were polygonal in the basal layer and became flattened in superficial layers. The epithelium displayed a phenotype similar to human corneal epithelium in vivo. The differentiation markers, keratin 3, involucrin and connexin 43, were expressed in full or superficial layers. Interestingly, certain basal cells were immunopositive to antibodies against limbal stem/progenitor cell markers ABCG2 and p63, which are usually negative in corneal epithelium in vivo. It suggests that this bioengineered corneal epithelium shared some characteristics of human limbal epithelium in vivo. This engineered epithelium was able to regenerate in 4 days following from a 4mm-diameter wound created by a filter paper soaked with 1 N NaOH. This corneal construct survived well after xeno-transplantation to the back of a nude mouse. The transplanted epithelium remained multilayer and became thicker with a phenotype similar to human corneal epithelium. Our findings demonstrate that natural corneal stroma is an optimal substrate for tissue bioengineering, and a native-like corneal construct has been created with epithelium containing limbal stem cells. This construct may have great potential for clinical use in

  6. Native-likeness in second language lexical categorization reflects individual language history and linguistic community norms.

    Science.gov (United States)

    Zinszer, Benjamin D; Malt, Barbara C; Ameel, Eef; Li, Ping

    2014-01-01

    SECOND LANGUAGE LEARNERS FACE A DUAL CHALLENGE IN VOCABULARY LEARNING: First, they must learn new names for the 100s of common objects that they encounter every day. Second, after some time, they discover that these names do not generalize according to the same rules used in their first language. Lexical categories frequently differ between languages (Malt et al., 1999), and successful language learning requires that bilinguals learn not just new words but new patterns for labeling objects. In the present study, Chinese learners of English with varying language histories and resident in two different language settings (Beijing, China and State College, PA, USA) named 67 photographs of common serving dishes (e.g., cups, plates, and bowls) in both Chinese and English. Participants' response patterns were quantified in terms of similarity to the responses of functionally monolingual native speakers of Chinese and English and showed the cross-language convergence previously observed in simultaneous bilinguals (Ameel et al., 2005). For English, bilinguals' names for each individual stimulus were also compared to the dominant name generated by the native speakers for the object. Using two statistical models, we disentangle the effects of several highly interactive variables from bilinguals' language histories and the naming norms of the native speaker community to predict inter-personal and inter-item variation in L2 (English) native-likeness. We find only a modest age of earliest exposure effect on L2 category native-likeness, but importantly, we find that classroom instruction in L2 negatively impacts L2 category native-likeness, even after significant immersion experience. We also identify a significant role of both L1 and L2 norms in bilinguals' L2 picture naming responses.

  7. Native-Likeness in Second Language Lexical Categorization Reflects Individual Language History and Linguistic Community Norms

    Directory of Open Access Journals (Sweden)

    Benjamin D Zinszer

    2014-10-01

    Full Text Available Second language learners face a dual challenge in vocabulary learning: First, they must learn new names for the hundreds of common objects that they encounter every day. Second, after some time, they discover that these names do not generalize according to the same rules used in their first language. Lexical categories frequently differ between languages (Malt et al., 1999, and successful language learning requires that bilinguals learn not just new words but new patterns for labeling objects. In the present study, Chinese learners of English with varying language histories and resident in two different language settings (Beijing, China and State College, PA, USA named 67 photographs of common serving dishes (e.g., cups, plates, and bowls in both Chinese and English. Participants’ response patterns were quantified in terms of similarity to the responses of functionally monolingual native speakers of Chinese and English and showed the cross-language convergence previously observed in simultaneous bilinguals (Ameel et al., 2005. For English, bilinguals’ names for each individual stimulus were also compared to the dominant name generated by the native speakers for the object. Using two statistical models, we disentangle the effects of several highly interactive variables from bilinguals' language histories and the naming norms of the native speaker community to predict inter-personal and inter-item variation in L2 (English native-likeness. We find only a modest age of earliest exposure effect on L2 category native-likeness, but importantly, we find that classroom instruction in L2 negatively impacts L2 category native-likeness, even after significant immersion experience. We also identify a significant role of both L1 and L2 norms in bilinguals’ L2 picture naming responses.

  8. Native-likeness in second language lexical categorization reflects individual language history and linguistic community norms

    Science.gov (United States)

    Zinszer, Benjamin D.; Malt, Barbara C.; Ameel, Eef; Li, Ping

    2014-01-01

    Second language learners face a dual challenge in vocabulary learning: First, they must learn new names for the 100s of common objects that they encounter every day. Second, after some time, they discover that these names do not generalize according to the same rules used in their first language. Lexical categories frequently differ between languages (Malt et al., 1999), and successful language learning requires that bilinguals learn not just new words but new patterns for labeling objects. In the present study, Chinese learners of English with varying language histories and resident in two different language settings (Beijing, China and State College, PA, USA) named 67 photographs of common serving dishes (e.g., cups, plates, and bowls) in both Chinese and English. Participants’ response patterns were quantified in terms of similarity to the responses of functionally monolingual native speakers of Chinese and English and showed the cross-language convergence previously observed in simultaneous bilinguals (Ameel et al., 2005). For English, bilinguals’ names for each individual stimulus were also compared to the dominant name generated by the native speakers for the object. Using two statistical models, we disentangle the effects of several highly interactive variables from bilinguals’ language histories and the naming norms of the native speaker community to predict inter-personal and inter-item variation in L2 (English) native-likeness. We find only a modest age of earliest exposure effect on L2 category native-likeness, but importantly, we find that classroom instruction in L2 negatively impacts L2 category native-likeness, even after significant immersion experience. We also identify a significant role of both L1 and L2 norms in bilinguals’ L2 picture naming responses. PMID:25386149

  9. Second Language Processing Shows Increased Native-Like Neural Responses after Months of No Exposure

    Science.gov (United States)

    Morgan-Short, Kara; Finger, Ingrid; Grey, Sarah; Ullman, Michael T.

    2012-01-01

    Although learning a second language (L2) as an adult is notoriously difficult, research has shown that adults can indeed attain native language-like brain processing and high proficiency levels. However, it is important to then retain what has been attained, even in the absence of continued exposure to the L2—particularly since periods of minimal or no L2 exposure are common. This event-related potential (ERP) study of an artificial language tested performance and neural processing following a substantial period of no exposure. Adults learned to speak and comprehend the artificial language to high proficiency with either explicit, classroom-like, or implicit, immersion-like training, and then underwent several months of no exposure to the language. Surprisingly, proficiency did not decrease during this delay. Instead, it remained unchanged, and there was an increase in native-like neural processing of syntax, as evidenced by several ERP changes—including earlier, more reliable, and more left-lateralized anterior negativities, and more robust P600s, in response to word-order violations. Moreover, both the explicitly and implicitly trained groups showed increased native-like ERP patterns over the delay, indicating that such changes can hold independently of L2 training type. The results demonstrate that substantial periods with no L2 exposure are not necessarily detrimental. Rather, benefits may ensue from such periods of time even when there is no L2 exposure. Interestingly, both before and after the delay the implicitly trained group showed more native-like processing than the explicitly trained group, indicating that type of training also affects the attainment of native-like processing in the brain. Overall, the findings may be largely explained by a combination of forgetting and consolidation in declarative and procedural memory, on which L2 grammar learning appears to depend. The study has a range of implications, and suggests a research program with

  10. Effect of Green Tea Extract Encapsulated Into Chitosan Nanoparticles on Hepatic Fibrosis Collagen Fibers Assessed by Atomic Force Microscopy in Rat Hepatic Fibrosis Model.

    Science.gov (United States)

    Safer, Abdel-Majeed A; Hanafy, Nomany A; Bharali, Dhruba J; Cui, Huadong; Mousa, Shaker A

    2015-09-01

    The present study examined the effect of Green Tea Extract (GTE) encapsulated into Chitosan Nanoparticles (CS-NPs) on hepatic fibrosis in rat model as determined by atomic force microscopy (AFM). The bioactive compounds in GTE encapsulated into CS-NPs were determined using LC-MS/MS method. Additionally, the uptake of GTE-CS NPs in HepG2 cells showed enhanced uptake. In experimental fibrosis model, AFM was used as a high resolution microscopic tool to investigate collagen fibers as an indicator of hepatic fibrosis induced by treatment with CCl4. Paraffin sections of fibrotic liver tissues caused by CC4 treatment of rats and the effect of GTE-CS NPs treatment with or without CCl4 on hepatic fibrosis were examined. Liver tissues from the different groups of animals were de-waxed and processed as for normal H/E staining and Masson's trichrome staining to locate the proper area of ECM collagen in the CCl4 group versus collagen in liver tissues treated with the GTE-CS NPs with or without CCl4. Selected areas of paraffin sections were trimmed off and fixed flat on top of mica and inserted in the AFM stage. H/E staining, Masson's trichrome stained slides, and AFM images revealed that collagen fibers of 250 to 300 nm widths were abundant in the fibrotic liver samples while those of GTE-CS NPs were clear as in the control group. Data confirmed the hypothesis that GTE-CS NPs are effective in removing all the extracellular collagen caused by CCl4 in the hepatic fibrosis rat liver.

  11. Native-like brain processing of syntax can be attained by university foreign language learners.

    Science.gov (United States)

    Bowden, Harriet Wood; Steinhauer, Karsten; Sanz, Cristina; Ullman, Michael T

    2013-11-01

    Using event-related potentials (ERPs), we examined the neurocognition of late-learned second language (L2) Spanish in two groups of typical university foreign-language learners (as compared to native (L1) speakers): one group with only one year of college classroom experience, and low-intermediate proficiency (L2 Low), and another group with over three years of college classroom experience as well as 1-2 semesters of immersion experience abroad, and advanced proficiency (L2 Advanced). Semantic violations elicited N400s in all three groups, whereas syntactic word-order violations elicited LAN/P600 responses in the L1 and L2 Advanced groups, but not the L2 Low group. Indeed, the LAN and P600 responses were statistically indistinguishable between the L1 and L2 Advanced groups. The results support and extend previous findings. Consistent with previous research, the results suggest that L2 semantic processing always depends on L1-like neurocognitive mechanisms, whereas L2 syntactic processing initially differs from L1, but can shift to native-like processes with sufficient proficiency or exposure, and perhaps with immersion experience in particular. The findings further demonstrate that substantial native-like brain processing of syntax can be achieved even by typical university foreign-language learners. © 2013 Elsevier Ltd. All rights reserved.

  12. How Native-Like Can You Possibly Get: fMRI Evidence for Processing Accent

    Directory of Open Access Journals (Sweden)

    Ladan eGhazi-Saidi

    2015-10-01

    Full Text Available Introduction: If ever attained, adopting native-like accent is achieved late in the learning process. Resemblance between L2 and mother tongue can facilitate L2 learning. In particular, cognates (phonologically and semantically similar words across languages, offer the opportunity to examine the issue of foreign accent in quite a unique manner. Methods: Twelve Spanish speaking (L1 adults learnt French (L2 cognates and practiced their native-like pronunciation by means of a computerized method. After consolidation, they were tested on L1 and L2 oral picture- naming during fMRI scanning. Results and Discussion: The results of the present study show that there is a specific impact of accent on brain activation, even if L2 words are cognates, and belong to a pair of closely related languages. Results point that the insula is a key component of accent processing, which is in line with reports from patients with foreign accent syndrome (FSA following damage to the insula (e.g. Moreno-Torres et al., 2013; Katz et al., 2012; Tomasino et al., 2013, and healthy L2 learners (Chee et al., 2003. Thus, the left insula has been consistently related to the integration of attentional and working memory abilities, together with fine-tuning of motor programming to achieve optimal articulation.

  13. Native like helices in a specially designed β peptide in the gas phase.

    Science.gov (United States)

    Schubert, Franziska; Pagel, Kevin; Rossi, Mariana; Warnke, Stephan; Salwiczek, Mario; Koksch, Beate; von Helden, Gert; Blum, Volker; Baldauf, Carsten; Scheffler, Matthias

    2015-02-21

    In the natural peptides, helices are stabilized by hydrogen bonds that point backward along the sequence direction. Until now, there is only little evidence for the existence of analogous structures in oligomers of conformationally unrestricted β amino acids. We specifically designed the β peptide Ac-(β(2)hAla)6-LysH(+) to form native like helical structures in the gas phase. The design follows the known properties of the peptide Ac-Ala6-LysH(+) that forms a α helix in isolation. We perform ion-mobility mass-spectrometry and vibrational spectroscopy in the gas phase, combined with state-of-the-art density-functional theory simulations of these molecular systems in order to characterize their structure. We can show that the straightforward exchange of alanine residues for the homologous β amino acids generates a system that is generally capable of adopting native like helices with backward oriented H-bonds. By pushing the limits of theory and experiments, we show that one cannot assign a single preferred structure type due to the densely populated energy landscape and present an interpretation of the data that suggests an equilibrium of three helical structures.

  14. Collagen and Elastic Fibers in Vascular Remodeling of Varicose Vein%胶原和弹性纤维与曲张静脉管壁重塑

    Institute of Scientific and Technical Information of China (English)

    徐永波; 严菲

    2011-01-01

    曲张静脉管壁胶原和弹性纤维的病理改变,一直是静脉外科发展中存在着争议的问题.在此从正常下肢静脉胶原和弹性纤维的结构与功能、曲张静脉管壁胶原和弹性纤维的分布与含量及影响静脉管壁胶原和弹性纤维改变的因素进行综述.认为静脉压增高和缺氧是静脉管壁平滑肌细胞和细胞外基质发生变化的启动因素.曲张静脉管壁胶原和弹性纤维的病理改变受其血管平滑肌细胞、基质金属蛋白酶、氧自由基、Fas基因等诸因素影响.%The pathogenesis of collagen and elastic fiber alteration in varicose vein has been always controversial throughout the development of venous surgery.This article reviews the structure and function of collagen and elastic fibers in normal lower limb vein, their distribution and content in varicose vein wall, and contributing factors of their changes in venous wall.Increased venous pressure and hypoxia are thought to initiate the alteration in venous wall smooth muscle cells and extracellular matrix.The pathogenesis of collagen and elastic fiber alteration in varicose vein results from vascular smooth muscle cells,matrix metalloproteinases, oxygen radicals, and Fas gene.

  15. Enigmatic insight into collagen

    Directory of Open Access Journals (Sweden)

    Shrutal Narendra Deshmukh

    2016-01-01

    Full Text Available Collagen is a unique, triple helical molecule which forms the major part of extracellular matrix. It is the most abundant protein in the human body, representing 30% of its dry weight. It is the fibrous structural protein that makes up the white fibers (collagen fibers of skin, tendons, bones, cartilage and all other connective tissues. Collagens are not only essential for the mechanical resistance and resilience of multicellular organisms, but are also signaling molecules defining cellular shape and behavior. The human body has at least 16 types of collagen, but the most prominent types are I, II and III. Collagens are produced by several cell types and are distinguishable by their molecular compositions, morphologic characteristics, distribution, functions and pathogenesis. This is the major fibrous glycoprotein present in the extracellular matrix and in connective tissue and helps in maintaining the structural integrity of these tissues. It has a triple helical structure. Various studies have proved that mutations that modify folding of the triple helix result in identifiable genetic disorders. Collagen diseases share certain similarities with autoimmune diseases, because autoantibodies specific to each collagen disease are produced. Therefore, this review highlights the role of collagen in normal health and also the disorders associated with structural and functional defects in collagen.

  16. Binding of inferred germline precursors of broadly neutralizing HIV-1 antibodies to native-like envelope trimers.

    Science.gov (United States)

    Sliepen, Kwinten; Medina-Ramírez, Max; Yasmeen, Anila; Moore, John P; Klasse, Per Johan; Sanders, Rogier W

    2015-12-01

    HIV-1 envelope glycoproteins (Env) and Env-based immunogens usually do not interact efficiently with the inferred germline precursors of known broadly neutralizing antibodies (bNAbs). This deficiency may be one reason why Env and Env-based immunogens are not efficient at inducing bNAbs. We evaluated the binding of 15 inferred germline precursors of bNAbs directed to different epitope clusters to three soluble native-like SOSIP.664 Env trimers. We found that native-like SOSIP.664 trimers bind to some inferred germline precursors of bNAbs, particularly ones involving the V1/V2 loops at the apex of the trimer. The data imply that native-like SOSIP.664 trimers will be an appropriate platform for structure-guided design improvements intended to create immunogens able to target the germline precursors of bNAbs.

  17. 同轴静电纺丝法制备PVA-胶原微纳米纤维%Preparation of PVA-collagen micro-nano fibers by coaxial electrospinning

    Institute of Scientific and Technical Information of China (English)

    张晓莉; 汤克勇; 郑学晶

    2016-01-01

    In this paper, the PVA-collagen micro-nano fibers were prepared by coaxial electrospinning technique. The effects of collagen concentration and parameters of the coaxial electrospinning process on the morphology of PVA-collagen were investigated. Results show that the greater shell collagen concentration is, the more easily obtained beaded PVA-collagen micro-nano fibers;when the spinning voltage is 15~20 kV, the spinning distance is 15~20 cm, and the flow rate of shell collagen solution is 0. 1 mL/h, micro-nano fibers with relatively smooth surface can be obtained.%通过同轴静电纺丝技术,制备以胶原为壳层而PVA为核层的微纳米纤维,研究壳层胶原溶液的浓度和同轴静电纺丝工艺参数对PVA-胶原微纳米纤维形貌的影响.研究结果表明:壳层胶原溶液浓度越大,越容易获得串珠状PVA-胶原微纳米纤维;当纺丝电压为15~20 kV,纺丝距离为15~20 cm,壳层胶原溶液流速为0.1 mL/h时,可以获得表面相对光滑的微纳米纤维.

  18. Study on Extracting Collagen Fibers of Bovine Tendonwith Acid - Enzyme Binding Assay%酸-酶结合法提取牛肌腱胶原纤维的研究

    Institute of Scientific and Technical Information of China (English)

    贾淑平; 吴勇川

    2012-01-01

    The high purity collagen fibers was obtained after salting out, dialysis, centrifugation and freeze-dried. Through determining the hydroxyproline content of the collagen fibers, it was found that the collagen fibers of the Acid - enzyme binding with 44.9% much higher than that of enzymatic alone with33.8%. The results of the collagen fibers infrared scanning and Differential Scanning Calorimetry (DSC) showed that the collagen fibers was provided with the complete triple helix structure. And the DSC scan results showed that the denaturation temperature of the freeze-dried collagen fibers was 60℃.%以牛肌腱为原料,分别利用酸一酶结合法和酶法从冻干碎块中提取胶原纤维,经过盐析、透析、离心和冷冻干燥后制备得到高纯度胶原纤维.通过测定胶原纤维中羟脯氨酸的含量,得到酸一酶结合法的得率为44.9%,远大于单独用酶提取胶原纤维的得率33.8%.对制备的胶原纤维进行红外扫描和差示量热扫描(DSC),结果表明胶原纤维保持了完整的三股螺旋结构,DSC扫描结果表明冻干胶原纤维的变性温度为60.8~C.

  19. The Preparation of Aminated Collagen Fiber and its Application in Adsorption of Dyes%氨基化胶原纤维的制备及其对染料的吸附性能研究

    Institute of Scientific and Technical Information of China (English)

    强涛涛; 罗敏; 步巧巧; 王学川

    2012-01-01

    The aminated collagen fiber ( ACF) was prepared by modifying collagen fiber (CF) with elhylenediamine and cynurie chloride as a crosslinking agent. The appropriate modification conditions were optimized by single factor experiment method; the reaction molar ratio n(CNC) : n{ - NH2) was 1.4, the reaction time of ice water bath was 3h, the temperature of the second phase was 45t and the reaction time was 4 h, the temperature of the third phase was 70 ℃ and the reaction time was 3h. The content of amino of collagen fiber and aminated collagen fiber were measured by the method of salicylaldehyde. The structures of collagen fiber and aminated collagen fiber were characterized and analyzed by SEM and FTIR respectively.%以乙二胺(EDA)为原料、三聚氰氯(CNC)为交联剂对制备的酸松弛猪皮胶原纤维(CF)进行氨基化改性,制备以胶原纤维为基质的吸附剂;并通过单因素实验法优化出了改性的最佳条件:反应物质的量比n(CNC)∶n(-NH2)=1.4,第一阶段冰水浴时间3h,第二阶段反应温度为45℃,反应时间4h,第三阶段反应温度为70℃,反应时间3h;用水杨醛法测定了改性前后胶原纤维中氨基含量的变化,并用SEM、和FTIR分别对改性前后胶原纤维的组织形态、分子结构进行了表征.

  20. Engineering and Characterization of a Fluorescent Native-Like HIV-1 Envelope Glycoprotein Trimer

    Directory of Open Access Journals (Sweden)

    Kwinten Sliepen

    2015-10-01

    Full Text Available Generation of a stable, soluble mimic of the HIV-1 envelope glycoprotein (Env trimer on the virion surface has been considered an important first step for developing a successful HIV-1 vaccine. Recently, a soluble native-like Env trimer (BG505 SOSIP.664 has been described. This protein has facilitated major advances in the HIV-1 vaccine field, since it was the first Env immunogen that induced consistent neutralizing antibodies against a neutralization-resistant (tier 2 virus. Moreover, BG505 SOSIP.664 enabled elucidation of the atomic resolution structure of the Env trimer and facilitated the isolation and characterization of new broadly neutralizing antibodies against HIV-1. Here, we designed and characterized the BG505 SOSIP.664 trimer fused to fluorescent superfolder GFP (sfGFP, a GFP variant that allows efficient folding (BG505 SOSIP.664-sfGFP. Despite the presence of the sfGFP, the Env protein largely retained its morphology, antigenicity, glycan composition, and thermostability. In addition, we show that BG505 SOSIP.664-sfGFP can be used for fluorescence-based assays, such as flow cytometry.

  1. Developing Native-Like Listening Comprehension Materials Perceptions of a Digital Approach

    Directory of Open Access Journals (Sweden)

    Herri Mulyono

    2016-01-01

    Full Text Available This paper reported the attempt teachers did in developing native-like (NLS listening materials for their EFL learners using a text-to-speech (TTS technology. Observation was carried out to record teachers’ procedures for developing NLS materials. Interview with teachers were undertaken to explore their’ perceptions towards the NLS listening materials and the benefits they gained from developing instructional media using technology. In addition, a questionnaire was distributed to 65 eight-grade pupils to gather information related to their opinions regarding the listening materials developed and used by their teachers. The findings show that teachers and pupils responded positively towards the NLS materials for listening comprehension. In addition, teachers were found to have more confidence in teaching listening skill while using the technology. There are three conditions which endorse this teaching confidence: the suitability of instructional materials used with the learning curriculum and pupils’ level of English proficiency, teachers’ self-efficacy to the teaching task, and the integration of technology in classroom teaching. The study suggests that TTS system can be used as computer assisted language learning (CALL application particularly in the development of listening comprehension materials. The study also confirms earlier studies that teacher professional development can be promoted through integrated training on technology for classroom use.

  2. Influence of Guanidine Hydrochloride on Dry Heat Shrinkage Behaviors of Collagen Fibers%盐酸胍对皮胶原纤维干热收缩行为的影响及其可逆性

    Institute of Scientific and Technical Information of China (English)

    王芳; 汤克勇; 潘洪波

    2011-01-01

    Collagen fibers were processed in guanidine hydrochloride solutions of different concentrations, and the dry heat shrinkage behaviors of the collagen fibers were studied by thermal platform microscope. It was indicated that the dry heat shrinkage temperature of the samples was obviously decreased by the guanidine hydrochloride process. It decreased with increasing the guanidine hydrochloride concentrations to reach equilibrium, around 120cC. With increasing the guanidine hydrochloride concentration , the dry heat shrinkage ratio of collagen fibers was increased firstly, followed by a decreasing. There is no chemical reaction between collagen fibers and guanidine hydrochloride. Only a physical action exists between collagen fibers and guanidine hydrochloride. It is reversible. Guanidine hydrochloride process may destroy the original hydrogen bonds in collagen fibers and change their aggregation structure. After guanidine hydrochloride process, the collagen structure is unstable, which may help the penetration and combination of leather chemicals with the collagen fibers in leather making.%以盐酸胍为改性剂,将皮胶原纤维在不同浓度盐酸胍溶液处理不同的时间后,研究了盐酸胍处理前后皮胶原纤维的干热收缩行为及其变化规律.研究发现:盐酸胍处理后皮胶原纤维的干热收缩温度明显降低,且随所用盐酸胍浓度的增大干热收缩温度逐渐减小,直至平衡,平衡时试样的收缩温度在120℃左右;其干热收缩率则随盐酸胍浓度的增大而先增大后减小.经过盐酸胍处理后,皮胶原纤维的结构变得不稳定,可以为以后其它材料渗透到皮胶原纤维内与皮胶原纤维间发生相互作用,创造必要的条件.

  3. Studies of chain substitution caused sub-fibril level differences in stiffness and ultrastructure of wildtype and oim/oim collagen fibers using multifrequency-AFM and molecular modeling.

    Science.gov (United States)

    Li, Tao; Chang, Shu-Wei; Rodriguez-Florez, Naiara; Buehler, Markus J; Shefelbine, Sandra; Dao, Ming; Zeng, Kaiyang

    2016-11-01

    Molecular alteration in type I collagen, i.e., substituting the α2 chain with α1 chain in tropocollagen molecule, can cause osteogenesis imperfecta (OI), a brittle bone disease, which can be represented by a mouse model (oim/oim). In this work, we use dual-frequency Atomic Force Microscopy (AFM) and incorporated with molecular modeling to quantify the ultrastructure and stiffness of the individual native collagen fibers from wildtype (+/+) and oim/oim diseased mice humeri. Our work presents direct experimental evidences that the +/+ fibers have highly organized and compact ultrastructure and corresponding ordered stiffness distribution. In contrast, oim/oim fibers have ordered but loosely packed ultrastructure with uncorrelated stiffness distribution, as well as local defects. The molecular model also demonstrates the structural and molecular packing differences between +/+ and oim/oim collagens. The molecular mutation significantly altered sub-fibril structure and mechanical property of collagen fibers. This study can give the new insight for the mechanisms and treatment of the brittle bone disease.

  4. Direct Conversion of an Enzyme from Native-like to Amyloid-like Aggregates within Inclusion Bodies.

    Science.gov (United States)

    Elia, Francesco; Cantini, Francesca; Chiti, Fabrizio; Dobson, Christopher Martin; Bemporad, Francesco

    2017-06-20

    The acylphosphatase from Sulfolobus solfataricus (Sso AcP) is a globular protein able to aggregate in vitro from a native-like conformational ensemble without the need for a transition across the major unfolding energy barrier. This process leads to the formation of assemblies in which the protein retains its native-like structure, which subsequently convert into amyloid-like aggregates. Here, we investigate the mechanism by which Sso AcP aggregates in vivo to form bacterial inclusion bodies after expression in E. coli. Shortly after the initiation of expression, Sso AcP is incorporated into inclusion bodies as a native-like protein, still exhibiting small but significant enzymatic activity. Additional experiments revealed that this overall process of aggregation is enhanced by the presence of the unfolded N-terminal region of the sequence and by destabilization of the globular segment of the protein. At later times, the Sso AcP molecules in the inclusion bodies lose their native-like properties and convert into β-sheet-rich amyloid-like structures, as indicated by their ability to bind thioflavin T and Congo red. These results show that the aggregation behavior of this protein is similar in vivo to that observed in vitro, and that, at least for a predominant part of the protein population, the transition from a native to an amyloid-like structure occurs within the aggregate state. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  5. Coexistence of Native-Like and Non-Native Cytochrome c on Anionic Liposomes with Different Cardiolipin Content.

    Science.gov (United States)

    Pandiscia, Leah A; Schweitzer-Stenner, Reinhard

    2015-10-08

    We employed a combination of fluorescence, visible circular dichroism, and absorption spectroscopy to study the conformational changes of ferricytochrome c upon its binding to cardiolipin-containing small unilamellar vesicles. The measurements were performed as a function of the cardiolipin concentration, the cardiolipin content of the liposomes, and the NaCl concentration of the solvent. The data were analyzed with a novel model that combines a single binding step with a conformational equilibrium between native-like and non-native-like proteins bound to the membrane surface. The equilibrium between the two conformations, which themselves are comprised of structurally slightly different subconformations, shifts to the more non-native-like conformation with increasing cardiolipin concentration. For the binding isotherms described in this paper, we explicitly considered the enthalpic and entropic contributions of molecular crowding to protein binding at low lipid concentrations and high occupancy of the liposome surface. Increasing the CL content of liposomes increases the overall binding affinity but makes the conformational distribution much more susceptible to the influence of sodium and chloride ions, which shifts the equilibrium toward the more native-like state and directly inhibits binding, particularly to liposomes with 100% cardiolipin content. Spectroscopic evidence further suggests that a fraction of the non-native conformers adopts a pentacoordinated state similar to those obtained in class C peroxidases. On the basis of our results, we propose a hypothesis that describes the balance between facilitating and impeding forces controlling the peroxidase activity of cytochrome c in the inner membrane space of mitochondria.

  6. Non-Enzymatic Decomposition of Collagen Fibers by a Biglycan Antibody and a Plausible Mechanism for Rheumatoid Arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Antipova, Olga; Orgel, Joseph P.R.O. (IIT)

    2013-04-08

    Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory and destructive joint disorder that affects tens of millions of people worldwide. Normal healthy joints maintain a balance between the synthesis of extracellular matrix (ECM) molecules and the proteolytic degradation of damaged ones. In the case of RA, this balance is shifted toward matrix destruction due to increased production of cleavage enzymes and the presence of (autoimmune) immunoglobulins resulting from an inflammation induced immune response. Herein we demonstrate that a polyclonal antibody against the proteoglycan biglycan (BG) causes tissue destruction that may be analogous to that of RA affected tissues. The effect of the antibody is more potent than harsh chemical and/or enzymatic treatments designed to mimic arthritis-like fibril de-polymerization. In RA cases, the immune response to inflammation causes synovial fibroblasts, monocytes and macrophages to produce cytokines and secrete matrix remodeling enzymes, whereas B cells are stimulated to produce immunoglobulins. The specific antigen that causes the RA immune response has not yet been identified, although possible candidates have been proposed, including collagen types I and II, and proteoglycans (PG's) such as biglycan. We speculate that the initiation of RA associated tissue destruction in vivo may involve a similar non-enzymatic decomposition of collagen fibrils via the immunoglobulins themselves that we observe here ex vivo.

  7. Experimental validation of an extended Jones matrix calculus model to study the 3D structural orientation of the collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Kasaragod, Deepa K; Lu, Zenghai; Jacobs, James; Matcher, Stephen J

    2012-03-01

    We report results to verify a theoretical framework to analyze the 3D depth-wise structural organization of collagen fibers in articular cartilage using polarization-sensitive optical coherence tomography. Apparent birefringence data obtained from multi-angle measurements using a time domain polarization-sensitive optical coherence tomography system has been compared with simulated data based on the extended Jones matrix calculus. Experimental data has been shown to agree with the lamellar model previously proposed for the cartilage microstructure based on scanning electron microscopy data. This tool could have potential application in mapping the collagen structural orientation information of cartilage non-invasively during arthroscopy.

  8. Collagenous gastroduodenitis.

    Science.gov (United States)

    Rustagi, Tarun; Rai, Mridula; Scholes, John V

    2011-10-01

    Collagenous gastroduodenitis is a rare histopathologic entity characterized by marked subepithelial collagen deposition with associated mucosal inflammatory infiltrate. Only 4 cases have been reported, of which 3 had associated collagenous colitis. Collagenous gastroduodenitis without colonic involvement is exceptionally rare with only 1 case reported so far in the literature. We present a case of a 68-year-old woman with dyspepsia and mild anemia, who was found to have nodular gastric and duodenal mucosa on endoscopic examination. Histopathology showed collagenous gastroduodenitis. To the best of our knowledge, this is the second (and first in English literature) reported case of isolated collagenous gastroduodenitis.

  9. A titanium surface with nano-ordered spikes and pores enhances human dermal fibroblastic extracellular matrix production and integration of collagen fibers.

    Science.gov (United States)

    Yamada, Masahiro; Kato, Eiji; Yamamoto, Akiko; Sakurai, Kaoru

    2016-02-02

    The acquisition of substantial dermal sealing determines the prognosis of percutaneous titanium-based medical devices or prostheses. A nano-topographic titanium surface with ordered nano-spikes and pores has been shown to induce periodontal-like connective tissue attachment and activate gingival fibroblastic functions. This in vitro study aimed to determine whether an alkali-heat (AH) treatment-created nano-topographic titanium surface could enhance human dermal fibroblastic functions and binding strength to the deposited collagen on the titanium surface. The surface topographies of commercially pure titanium machined discs exposed to two different AH treatments were evaluated. Human dermal fibroblastic cultures grown on the discs were evaluated in terms of cellular morphology, proliferation, extracellular matrix (ECM) and proinflammatory cytokine synthesis, and physicochemical binding strength of surface-deposited collagen. An isotropically-patterned, shaggy nano-topography with a sponge-like inner network and numerous well-organized, anisotropically-patterned fine nano-spikes and pores were observed on each nano-topographic surface type via scanning electron microscopy. In contrast to the typical spindle-shaped cells on the machined surfaces, the isotropically- and anisotropically-patterned nano-topographic titanium surfaces had small circular/angular cells containing contractile ring-like structures and elongated, multi-shaped cells with a developed cytoskeletal network and multiple filopodia and lamellipodia, respectively. These nano-topographic surfaces enhanced dermal-related ECM synthesis at both the protein and gene levels, without proinflammatory cytokine synthesis or reduced proliferative activity. Deposited collagen fibers were included in these surfaces and sufficiently bound to the nano-topographies to resist the physical, enzymatic and chemical detachment treatments, in contrast to machined surfaces. Well-organized, isotropically

  10. Explicit and implicit second language training differentially affect the achievement of native-like brain activation patterns.

    Science.gov (United States)

    Morgan-Short, Kara; Steinhauer, Karsten; Sanz, Cristina; Ullman, Michael T

    2012-04-01

    It is widely believed that adults cannot learn a foreign language in the same way that children learn a first language. However, recent evidence suggests that adult learners of a foreign language can come to rely on native-like language brain mechanisms. Here, we show that the type of language training crucially impacts this outcome. We used an artificial language paradigm to examine longitudinally whether explicit training (that approximates traditional grammar-focused classroom settings) and implicit training (that approximates immersion settings) differentially affect neural (electrophysiological) and behavioral (performance) measures of syntactic processing. Results showed that performance of explicitly and implicitly trained groups did not differ at either low or high proficiency. In contrast, electrophysiological (ERP) measures revealed striking differences between the groups' neural activity at both proficiency levels in response to syntactic violations. Implicit training yielded an N400 at low proficiency, whereas at high proficiency, it elicited a pattern typical of native speakers: an anterior negativity followed by a P600 accompanied by a late anterior negativity. Explicit training, by contrast, yielded no significant effects at low proficiency and only an anterior positivity followed by a P600 at high proficiency. Although the P600 is reminiscent of native-like processing, this response pattern as a whole is not. Thus, only implicit training led to an electrophysiological signature typical of native speakers. Overall, the results suggest that adult foreign language learners can come to rely on native-like language brain mechanisms, but that the conditions under which the language is learned may be crucial in attaining this goal.

  11. Collagenous sprue

    DEFF Research Database (Denmark)

    Soendergaard, Christoffer; Riis, Lene Buhl; Nielsen, Ole Haagen

    2014-01-01

    Collagenous sprue is a rare clinicopathological condition of the small bowel. It is characterised by abnormal subepithelial collagen deposition and is typically associated with malabsorption, diarrhoea and weight loss. The clinical features of collagenous sprue often resemble those of coeliac dis...... disease and together with frequent histological findings like mucosal thinning and intraepithelial lymphocytosis the diagnosis may be hard to reach without awareness of this condition. While coeliac disease is treated using gluten restriction, collagenous sprue is, however, not improved...

  12. Analysis of Native-Like Proteins and Protein Complexes Using Cation to Anion Proton Transfer Reactions (CAPTR)

    Science.gov (United States)

    Laszlo, Kenneth J.; Bush, Matthew F.

    2015-12-01

    Mass spectra of native-like protein complexes often exhibit narrow charge-state distributions, broad peaks, and contributions from multiple, coexisting species. These factors can make it challenging to interpret those spectra, particularly for mixtures with significant heterogeneity. Here we demonstrate the use of ion/ion proton transfer reactions to reduce the charge states of m/ z-selected, native-like ions of proteins and protein complexes, a technique that we refer to as cation to anion proton transfer reactions (CAPTR). We then demonstrate that CAPTR can increase the accuracy of charge state assignments and the resolution of interfering species in native mass spectrometry. The CAPTR product ion spectra for pyruvate kinase exhibit ~30 peaks and enable unambiguous determination of the charge state of each peak, whereas the corresponding precursor spectra exhibit ~6 peaks and the assigned charge states have an uncertainty of ±3%. 15+ bovine serum albumin and 21+ yeast enolase dimer both appear near m/ z 4450 and are completely unresolved in a mixture. After a single CAPTR event, the resulting product ions are baseline resolved. The separation of the product ions increases dramatically after each subsequent CAPTR event; 12 events resulted in a 3000-fold improvement in separation relative to the precursor ions. Finally, we introduce a framework for interpreting and predicting the figures of merit for CAPTR experiments. More generally, these results suggest that CAPTR strongly complements other mass spectrometry tools for analyzing proteins and protein complexes, particularly those in mixtures.

  13. Changes of muscle tissue and collagen fibers structure of sea cucumber ( Stichipus japonicus ) during heated treatment%不同加热温度下刺参肌肉组织与胶原纤维结构的变化

    Institute of Scientific and Technical Information of China (English)

    高昕; 刘莲凤; 刘倩; 黄金发; 付晓婷; 许加超

    2012-01-01

    Sea cucumber Stichopus japonicus has become an important cultivated aquatic species in China in recent years. Previous studies mainly focused on the food sources, nutrition values, biological activity and structure of acid polysaccharide. However, these studies do not have a tissue structural consideration on sea cucumber meat. In this paper, the changes of muscle tissue and collagen fibers structure from S. japonicus during heated treatment were studied, and the variation mechanism was analyzed. The structures of muscle tissue and collagen fibers were observed by a light microscope and a scanning microscope, meanwhile DSC tested the denaturation temperature of sea cucumber. Following were the results. The changes of tissue structure and collagen fibers after heating treatment were evident. Along with the increasing of heating temperature, the muscle fibers gradually aggregated and cross-linked, forming porous mesh structure. The collagen fiber structure shrunk, accompanied with collagen protein denaturation leading to fibers closely spaced. The changes of collagen fibers structure were more prominent compared with the overall tissue structure. DSC scanning curve of raw S. japonicus meat showed the denaturation temperature was 68. 92 ℃. Thermal denaturation of muscle protein during heating treatment resulted in the changes of tissue structure and collagen fibers.%为研究鲜活和不同加热温度下刺参体壁组织构造及其胶原纤维结构的变化,采用VanGieson染色法观察组织构造、采用细胞分裂扫描电镜法(cell-maceration/SEM)观察胶原纤维结构,同时利用示差扫描量热仪(DSC)测定刺参肌肉蛋白质的热收缩温度.结果发现,在不同加热温度条件下,刺参体壁组织构造及其胶原纤维结构均发生显著变化.随着加热温度的升高,刺参肌肉组织中纤维逐渐聚集交联,形成多孔网状结构;蛋白质发生热变性、胶原纤维结构收缩,导致纤维排列紧密,纤维间孔

  14. DSC Study of Collagen in Disc Disease

    Directory of Open Access Journals (Sweden)

    S. Skrzyński

    2009-01-01

    Full Text Available Differential scanning calorimetry (DSC has been used to estimate the effect of disc disease on the collagen helix-coil transition and morphology for tissue extracted from patients during surgical operation. Forty discs were obtained from patients with degenerative disc disease undergoing surgery for low back pain. The patients were in the age between 20 and 70 years old. The specimens were kept wet during DSC experiment. The data allow the comparison between thermal stability of collagen tissue from healthy patients and from patients suffering from disc disease. In the paper the comparison between thermal helix-coil transition for collagen fibers from patients suffering from disc disease and collagen fibers from healthy organisms has been discussed. The heating rate has an influence on the position on denaturation temperatures of collagen in disc tissues. Higher helix-coil transition temperature of collagen in degenerated disc suggests that additional intermolecular cross linking of collagen fibers occurs. Denaturation temperatures of collagen in degenerated male disc possess smaller values than in female ones. Disc disease induces changes in collagen structure and leads to formation of additional crosslinks between collagen fibers.

  15. Influence of electrospun fiber mesh size on hMSC oxygen metabolism in 3D collagen matrices: experimental and theoretical evidences.

    Science.gov (United States)

    Guaccio, Angela; Guarino, Vincenzo; Perez, Marco A Alvarez-; Cirillo, Valentina; Netti, Paolo A; Ambrosio, Luigi

    2011-08-01

    The traditional paradigm of tissue engineering of regenerating in vitro tissue or organs, through the combination of an artificial matrix and a cellular population has progressively changed direction. The most recent concept is the realization of a fully functional biohybrid, where both, the artificial and the biotic phase, concur in the formation of the novel organic matter. In this direction, interest is growing in approaches taking advantage of the control at micro- and nano-scale of cell material interaction based on the realization of elementary tassels of cells and materials which constitute the beginning point for the expansion of 3D more complex structures. Since a spontaneous assembly of all these components is expected, however, it becomes more fundamental than ever to define the features influencing cellular behavior, either they were material functional properties, or material architecture. In this work, it has been investigated the direct effect of electrospun fiber sizes on oxygen metabolism of h-MSC cells, when any other culture parameter was kept constant. To this aim, thin PCL electrospun membranes, with micro- and nano-scale texturing, were layered between two collagen slices up to create a sandwich structure (µC-PCL-C and nC-PCL-C). Cells were seeded on membranes, and the oxygen consumption was determined by a phosphorescence quenching technique. Results indicate a strong effect of the architecture of scaffolds on cell metabolism, also revealed by the increasing of HIF1-α gene expression in nC-PCL-C. These findings offer new insights into the role of materials in specific cell activities, also implying the existence of very interesting criteria for the control of tissue growth through the tuning of scaffold architecture.

  16. Collagen crosslinks in chondromalacia of the patella.

    Science.gov (United States)

    Väätäinen, U; Kiviranta, I; Jaroma, H; Arokosi, J; Tammi, M; Kovanen, V

    1998-02-01

    The aim of the study was to determine collagen concentration and collagen crosslinks in cartilage samples from chondromalacia of the patella. To study the extracellular matrix alterations associated to chondromalacia, we determined the concentration of collagen (hydroxyproline) and its hydroxylysylpyridinoline and lysylpyridinoline crosslinks from chondromalacia foci of the patellae in 12 patients and 7 controls from apparently normal cadavers. The structure of the collagen network in 8 samples of grades II-IV chondromalacia was examined under polarized light microscopy. The full-thickness cartilage samples taken with a surgical knife from chondromalacia lesions did not show changes in collagen, hydroxylysylpyridinoline and lysylpyridinoline concentration as compared with the controls. Polarized light microscopy showed decreased birefringence in the superficial cartilage of chondromalacia lesions, indicating disorganization or disappearance of collagen fibers in this zone. It is concluded that the collagen network shows gradual disorganization with the severity of chondromalacia lesion of the patella without changes in the concentration or crosslinks of collagen.

  17. Can advanced learners of spanish achieve native-like pronunciation? A re-examination of the critical period for accent Can advanced learners of spanish achieve native-like pronunciation? A re-examination of the critical period for accent

    Directory of Open Access Journals (Sweden)

    Frank A. Morris

    2008-04-01

    Full Text Available What is the foundation for the Critical Period Hypothesis?2 For the last thirty years, researchers have pondered whether learners of a second language can achieve native-like pronunciation. The first attempt at addressing the issue occurred in the early 1960’s. To account for the difficulty that some children had in acquiring a first or second language, the Critical Period Hypothesis was proposed (Penfield and Roberts, 1959; Lenneberg, 1967. It was postulated that there is a neurological based critical period, which ends at the onset of puberty. But after the critical period, mastery of a first or second language is no longer possible (Lenneberg, 1967. The cause for the lack of language attainment is attributed to a loss of neural plasticity. As the brain ages, it loses its "plasticity", and thus, its ability to learn languages. It was suggested that language learners who started to acquire a second language before the close of the critical period could achieve nativelike levels, but those who began to learn languages after the end of the critical period would not. What is the foundation for the Critical Period Hypothesis?2 For the last thirty years, researchers have pondered whether learners of a second language can achieve native-like pronunciation. The first attempt at addressing the issue occurred in the early 1960’s. To account for the difficulty that some children had in acquiring a first or second language, the Critical Period Hypothesis was proposed (Penfield and Roberts, 1959; Lenneberg, 1967. It was postulated that there is a neurological based critical period, which ends at the onset of puberty. But after the critical period, mastery of a first or second language is no longer possible (Lenneberg, 1967. The cause for the lack of language attainment is attributed to a loss of neural plasticity. As the brain ages, it loses its "plasticity", and thus, its ability to learn languages. It was suggested that language learners who

  18. Bioengineered collagens

    Science.gov (United States)

    Ramshaw, John AM; Werkmeister, Jerome A; Dumsday, Geoff J

    2014-01-01

    Mammalian collagen has been widely used as a biomedical material. Nevertheless, there are still concerns about the variability between preparations, particularly with the possibility that the products may transmit animal-based diseases. Many groups have examined the possible application of bioengineered mammalian collagens. However, translating laboratory studies into large-scale manufacturing has often proved difficult, although certain yeast and plant systems seem effective. Production of full-length mammalian collagens, with the required secondary modification to give proline hydroxylation, has proved difficult in E. coli. However, recently, a new group of collagens, which have the characteristic triple helical structure of collagen, has been identified in bacteria. These proteins are stable without the need for hydroxyproline and are able to be produced and purified from E. coli in high yield. Initial studies indicate that they would be suitable for biomedical applications. PMID:24717980

  19. Collagen-like peptides and peptide-polymer conjugates in the design of assembled materials

    OpenAIRE

    Luo, Tianzhi; Kiick, Kristi L.

    2013-01-01

    Collagen is the most abundant protein in mammals, and there has been long-standing interest in understanding and controlling collagen assembly in the design of new materials. Collagen-like peptides (CLP), also known as collagen-mimetic peptides (CMP) or collagen-related peptides (CRP), have thus been widely used to elucidate collagen triple helix structure as well as to produce higher-order structures that mimic natural collagen fibers. This mini-review provides an overview of recent progress...

  20. Preparation of Tanning Collagen Fiber Spun-lace Nonwovens Material with Immobilized Tannins%固化单宁鞣革胶原纤维水刺非织造材料的制备

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    本文将鞣革胶原纤维通过气流成网机成网,然后利用水刺试验机制备鞣革胶原纤维水刺材料,最后在黑荆树单宁水溶液及交联戊二醛水的作用下制得固化单宁鞣革胶原纤维水刺材料。并使用红外光谱和扫描电镜对其结构进行了表征及分析。由实验可知,鞣革胶原纤维热敏感温度为105℃,在后续加工过程中不宜超过此温度;鞣革胶原水刺材料固化单宁后,平方米克重增加约40%,但厚度变化不明显,MD方向、CD方向强力均得到提高,提高率分别为64.6%和23.6%,同时断裂伸长率分别下降55.6%和45.2%。固化单宁鞣革胶原水刺材料是便于使用的重金属吸附材料,其开发和利用为广泛应用鞣革胶原纤维材料提供了新的思路。%In this paper, tanning leather collagen fibers were formed a network by air-laid machine, then tanning collagen fiber spun-lace material was prepared by spun-lace testing machine,finally tanning collagen fiber spun-lace non-woven material with immobilized tannins was prepared in the black wattle tannins and glutaraldehyde solution. And infrared spectrometer and scanning electron microscope were used to analyze its structure and characterization. The experiment showed that tanning collagen fibers heat sensitive temperature was 105℃, which should be more than the temperature in the subsequent process;after tanning collagen spun-lace material immobilized tannins, gram weight per square metre increased about 40%, but the thickness change was not obvious, the MD and CD direction strength increased by 64.6%and 23.6%respectively , at the same time elongation at break decreased by 55.6% and 45.2% respectively; tanning collagen spun-lace material with immobilized tannins is a heavy metal adsorption material that is easy to use. Its development and use provide a new train of thought for widely using tanning collagen fiber material in the future.

  1. Stress controls the mechanics of collagen networks.

    Science.gov (United States)

    Licup, Albert James; Münster, Stefan; Sharma, Abhinav; Sheinman, Michael; Jawerth, Louise M; Fabry, Ben; Weitz, David A; MacKintosh, Fred C

    2015-08-04

    Collagen is the main structural and load-bearing element of various connective tissues, where it forms the extracellular matrix that supports cells. It has long been known that collagenous tissues exhibit a highly nonlinear stress-strain relationship, although the origins of this nonlinearity remain unknown. Here, we show that the nonlinear stiffening of reconstituted type I collagen networks is controlled by the applied stress and that the network stiffness becomes surprisingly insensitive to network concentration. We demonstrate how a simple model for networks of elastic fibers can quantitatively account for the mechanics of reconstituted collagen networks. Our model points to the important role of normal stresses in determining the nonlinear shear elastic response, which can explain the approximate exponential relationship between stress and strain reported for collagenous tissues. This further suggests principles for the design of synthetic fiber networks with collagen-like properties, as well as a mechanism for the control of the mechanics of such networks.

  2. [Collagenous colitis].

    Science.gov (United States)

    Lindström, C G

    1991-05-01

    Collagenous colitis is now regarded by an overwhelming majority of authors as a clinicopathological entity and has been taken up as a such in many text-books and diagnostic atlases (Morson & Dawson, 1990, Fenoglio-Preiser et al., 1989, Whitehead 1985, Whitehead 1989). A good, detailed review of cases of collagenous colitis published up to 1988 was performed by Perri et al. Collagenous colitis was also presented to a wider medical public through a clinicopathological conference case at Massachusetts General Hospital (Case 29-1988). Finally it may be added that collagenous colitis has been included in the new fourth edition of Robbins Pathologic Basis of Disease (Cotran, Kumar, Robbins, 1989), where the possibility of an autoimmune disease is stressed.

  3. Acquiring native-like intonation in Dutch and Spanish : Comparing the L1 and L2 of native speakers and second language learners

    NARCIS (Netherlands)

    van Maastricht, L.J.; Swerts, M.G.J.; Krahmer, E.J.

    2013-01-01

    ACQUIRING NATIVE-LIKE INTONATION IN DUTCH AND SPANISH Comparing the L1 and L2 of native speakers and second language learners Introduction Learning more about the interaction between the native language (L1) and the target language (L2) has been the aim of many studies on second language acquisition

  4. Acquiring native-like intonation in Dutch and Spanish : Comparing the L1 and L2 of native speakers and second language learners

    NARCIS (Netherlands)

    van Maastricht, L.J.; Swerts, M.G.J.; Krahmer, E.J.

    2013-01-01

    ACQUIRING NATIVE-LIKE INTONATION IN DUTCH AND SPANISH Comparing the L1 and L2 of native speakers and second language learners Introduction Learning more about the interaction between the native language (L1) and the target language (L2) has been the aim of many studies on second language acquisition

  5. The Critical Period for Second Language Pronunciation: Is There Such a Thing? Ten Case Studies of Late Starters who Attained a Native-like Hebrew Accent

    Science.gov (United States)

    Abu-Rabia, Salim; Kehat, Simona

    2004-01-01

    This paper investigates the critical period hypothesis (CPH) for the acquisition of a second language sound system (phonology) in a naturalistic setting. Ten cases of successful late-starters with a native-like Hebrew pronunciation are presented in an effort to determine possible variables that may account for their exceptional accomplishment. The…

  6. Structural Insights into the Interactions between Platelet Receptors and Fibrillar Collagen*

    OpenAIRE

    Herr, Andrew B.; Farndale, Richard W.

    2009-01-01

    Collagen peptides have been used to identify binding sites for several important collagen receptors, including integrin α2β1, glycoprotein VI, and von Willebrand factor. In parallel, the structures of these collagen receptors have been reported, and their interactions with collagen peptides have been studied. Recently, the three-dimensional structure of the intact type I collagen fiber from rat tail tendon has been resolved by fiber diffraction. It is now possible to map the binding sites of ...

  7. Synthesis and photo-catalytic activity of mesoporous TiO2 fiber using collagen fiber as a template%胶原纤维为模板制备介孔TiO2纤维及光催化活性研究

    Institute of Scientific and Technical Information of China (English)

    蔡莉

    2013-01-01

    以胶原纤维为模板,硫酸钛为钛源,通过 Ti (Ⅳ)与胶原纤维发生配位反应,将其负载于胶原纤维上,经过煅烧除去胶原纤维模板而获得具有介孔结构的TiO2纤维.通过场发射扫描电镜、N2吸附-脱附、广角XRD衍射、分子荧光光谱等分析手段对所制备的TiO2纤维的表面结构、孔结构和晶体结构等进行表征.实验结果表明,硫酸钛与胶原纤维质量比及煅烧温度明显影响TiO2纤维的表面形貌和孔结构.当硫酸钛与胶原纤维质量比为8∶5,煅烧温度为600℃,所制备的TiO2纤维能较完整地保留天然胶原纤维的形貌和有序的介孔结构,孔径分布集中在4.3 nm.酸性橙Ⅱ的光催化降解实验表明,具有介孔结构的 TiO2纤维的光催化活性明显高于无介孔结构的 Degussa P25.%Mesoporous TiO2 fiber was prepared using collagen fiber as the template and Ti(SO4 )2 as the titanium source.The Ti(Ⅳ)was loaded on collagen fiber by chelation reaction,and then the mesoporous TiO2 fiber was obtained after heat-treatment to remove the template of collagen fiber.The surface morphology and pore struc-ture of the as-prepared mesoporous TiO2 fiber were characterized by means of field emission scanning electron microscopy,N2 absorption-desorption isothermal method,wide angle XRD and photoluminescence spectra (PL).The experimental results indicated that the mass ratio of Ti(SO4 )2 to collagen fiber and calcination tem-perature significantly influenced the surface morphology and mesoporous structure of TiO2 fiber.When the mass ratio was 8∶5 and calcination temperature was 600 ℃,the morphology of nature collagen fiber was well preserved in the as-prepared mesoporous TiO2 fiber,and the mesoporous structure was in ordered and the pore size distribution was centered in 4.3 nm.The photo-catalytic degradation of acid orange Ⅱ experiments indicated that the photo-catalytic activity of the as-prepared mesoporous TiO2 fiber was much higher

  8. Study on the Microstructure and Properties of Composite Film of Collagen Fibers/PU by H2 O Induced Phase Separation%胶原纤维/聚氨酯湿法凝固复合膜的微观结构与性能研究

    Institute of Scientific and Technical Information of China (English)

    马兴元; 吕凌云; 蒋坤; 郭勇生; 李哓; 王海军

    2011-01-01

    采用铬鞣胶原纤维粉和聚氨酯(PU),通过湿法凝固的方法制备了胶原纤维/PU复合膜,测定了胶原纤维/PU复合膜的透水汽性、透气性和力学性能.利用SEM研究了胶原纤维/PU复合膜的微孔形态.利用DSC和TGA研究了胶原纤维/PU复合膜在程序控制温度下的热效应.研究结果表明胶原纤维/PU复合膜具有分布比较均匀并相互贯通的指形微孔,这种微孔结构能够提高膜的透水汽性和透气性,同时也会降低膜的物理机械性能.DSC和TGA分析胶原纤维和PU湿法凝固复合属于物理性复合.%Using chrome-tanned collagen fiber powder and polyurethane (PU), composite film of collagen fiber/PU has been made by H2O induced phase separation, and water vapor permeability, air permeability and mechanical properties have been measured. The form of micropores of composite film of collagen fiber/PU has been studied by SEM. The thermal effect of composite film of collagen fiber/PU has been studied by DSC and TGA under control temperature process. The results showed that the composite film of collagen fiber/ PU has finger pores and distribution are relatively uniform, which can improve the water vapor permeability and air permeability of film, but also reduce the mechanical properties of film. DSC and TGA analysis showed that the composite process of collagen fiber and polyurethane by H2O induced phase separation is physical composition.

  9. Production of collagen micro- and nanofibers for potential drug-carrier systems.

    Science.gov (United States)

    Aras, Onur; Kazanci, Murat

    2015-12-01

    Two different nano- and micro-collagen fiber production methods are introduced and discussed. First one is the electrospinning method, that is very common technique to produce nanofibers from different polymeric solutions and recently collagen solutions are employed to produce nanofibers for different biomedical applications. This technique is extremely versatile method to produce nanofibers in a relatively short time, easy to control the fiber diameter and orientation with small pore sizes and a high surface area. The second method is self-assembly of collagen micro-fibers by co-extrusion method. The collagen fibers are obtained without any cross-linker, by using mainly ionic interactions. We demonstrated that self-assembled collagen fibers have well preserved their native structure (0.90 PP-II fraction), when compared with electrospun collagen fibers (0.38 PP-II fraction). However, it was only possible to produce collagen fibers with nanodimensions by using electrospinning method.

  10. Optimization of Picrosirius red staining protocol to determine collagen fiber orientations in vaginal and uterine cervical tissues by Mueller polarized microscopy.

    Science.gov (United States)

    Nazac, André; Bancelin, Stéphane; Teig, Benjamin; Ibrahim, Bicher Haj; Fernandez, Hervé; Schanne-Klein, Marie-Claire; De Martino, Antonello

    2015-08-01

    Polarized microscopy provides unique information on anisotropic samples. In its most complete implementation, namely Mueller microscopy, this technique is well suited for the visualization of fibrillar proteins orientations, with collagen in the first place. However, the intrinsic optical anisotropy of unstained tissues has to be enhanced by Picrosirius Red (PR) staining to enable Mueller measurements. In this work, we compared the orientation mapping provided by Mueller and second harmonic generation (SHG) microscopies on PR stained samples of vaginal and uterine cervix tissues. SHG is a multiphoton technique that is highly specific to fibrillar collagen, and was taken as the "gold standard" for its visualization. We showed that Mueller microscopy can be safely used to determine collagen orientation in PR stained cervical tissue. In contrast, in vaginal samples, Mueller microscopy revealed orientations not only of collagen but also of other anisotropic structures. Thus PR is not fully specific to collagen, which necessitates comparison to SHG microscopy in every type of tissue. In addition to this study of PR specificity, we determined the optimal values of the staining parameters. We found that staining times of 5 min, and sample thicknesses of 5 µm were sufficient in cervical and vaginal tissues.

  11. Collagen telopeptides (cross-linking sites) play a role in collagen gel lattice contraction

    Science.gov (United States)

    Woodley, D. T.; Yamauchi, M.; Wynn, K. C.; Mechanic, G.; Briggaman, R. A.

    1991-01-01

    Solubilized interstitial collagens will form a fibrillar, gel-like lattice when brought to physiologic conditions. In the presence of human dermal fibroblasts the collagen lattice will contract. The rate of contraction can be determined by computer-assisted planemetry. The mechanisms involved in contraction are as yet unknown. Using this system it was found that the rate of contraction was markedly decreased when collagen lacking telopeptides was substituted for native collagen. Histidinohydroxylysinonorleucine (HHL) is a major stable trifunctional collagen cross-link in mature skin that involves a carboxyl terminal, telopeptide site 16c, the sixteenth amino acid residue from the carboxy terminal of the telopeptide region of alpha 1 (I) in type I collagen. Little, if any, HHL was present in native, purified, reconstituted, soluble collagen fibrils from 1% acetic acid-extracted 2-year-old bovine skin. In contrast, HHL cross-links were present (0.22 moles of cross-link per mole of collagen) in lattices of the same collagen contracted by fibroblasts. However, rat tail tendon does not contain HHL cross-links, and collagen lattices made of rat tail tendon collagen are capable of contraction. This suggests that telopeptide sites, and not mature HHL cross-links per se, are essential for fibroblasts to contract collagen lattices. Beta-aminopropionitrile fumarate (BAPN), a potent lathyrogen that perturbs collagen cross-linking by inhibition of lysyl oxidase, also inhibited the rate of lattice cell contraction in lattices composed of native collagen. However, the concentrations of BAPN that were necessary to inhibit the contraction of collagen lattices also inhibited fibroblast growth suggestive of cellular toxicity. In accordance with other studies, we found no inhibition of the rate of lattice contraction when fibronectin-depleted serum was used. Electron microscopy of contracted gels revealed typical collagen fibers with a characteristic axial periodicity. The data

  12. 胶原蛋白/PVA/碳纳米管复合纤维的结构与性能%Structure and properties of collagen/PVA/carbon nanotubes composite fibers

    Institute of Scientific and Technical Information of China (English)

    姜晓; 吴炜誉; 唐诗俊; 徐建军; 叶光斗

    2009-01-01

    Polyvinyl alcohol (PVA)/collagen/carbon nanotubes composite fiber was prepared from the composite solution of collagen and PVA incorporated with 0.05% -0.25% carbon nanotubes by mass fraction via wet spinning process.The structure and properties of the composite fiber were studied.The results showed that the carbon nanotubes had a fairly good compatibility with PVA and collagen and a uniform dispersion in the composite fiber.The crystallinity of the composite fiber was increased by 37.62% and the softening point in water by 5℃ and the moisture regain was decreased from 11.50% to 10.83% as the carbon nanotubes content was 0.25% by mass fraction.The breaking strength was increased by 57.07% as the carbon nanotubes content was 0.05% by mass fraction.%在胶原蛋白与聚乙烯醇(PVA)复合后的溶液中加入少量质量分数为0.05%~0.25%的碳纳米管,通过湿法纺丝制得PVA/胶原蛋白/碳纳米管复合纤维,研究了复合纤维的结构和性能.结果表明:碳纳米管与PVA和胶原蛋白有较好的相容性,在复合纤维中分散比较均匀.添加质量分数为0.25%碳纳米管时,复合纤维结晶度提高了37.62%,水中软化点提高了5℃,回潮率从11.50%下降到10.83%;加入质域分数为0.05%的碳纳米管时,复合纤维的断裂强度提高57.07%.

  13. Mineralization of Hydroxyapatite Regulated by Recombinant Human-like Collagen

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    We reported recombinant human-like type I collagen inducing growth of hydroxyapatite crystals in vitro in the form of self-assembly of nano-fibrils of mineralized collagen resembling extracellular matrix, which obey the same rules, but is superior to the collagen derived from animal tissues because the latter may carry diseases of animals and cause immunological reactions. The mineralized collagen fibrils aligned parallel to each other to form mineralized collagen fibers. Hydroxyapatite nanocrystals grew on the surface of these collagen fibrils with the c-axis of nanocrystals of HA orienting along the longitudinal axis of the fibrils.

  14. Collagenous gastritis.

    Science.gov (United States)

    Jin, Xiaoyi; Koike, Tomoyuki; Chiba, Takashi; Kondo, Yutaka; Ara, Nobuyuki; Uno, Kaname; Asano, Naoki; Iijima, Katsunori; Imatani, Akira; Watanabe, Mika; Shirane, Akio; Shimosegawa, Tooru

    2013-09-01

    In the present paper, we report a case of rare collagenous gastritis. The patient was a 25-year-old man who had experienced nausea, abdominal distention and epigastralgia since 2005. Esophagogastroduodenoscopy (EGD) carried out at initial examination by the patient's local doctor revealed an extensively discolored depression from the upper gastric body to the lower gastric body, mainly including the greater curvature, accompanied by residual mucosa with multiple islands and nodularity with a cobblestone appearance. Initial biopsies sampled from the nodules and accompanying atrophic mucosa were diagnosed as chronic gastritis. In August, 2011, the patient was referred to Tohoku University Hospital for observation and treatment. EGD at our hospital showed the same findings as those by the patient's local doctor. Pathological findings included a membranous collagen band in the superficial layer area of the gastric mucosa, which led to a diagnosis of collagenous gastritis. Collagenous gastritis is an extremely rare disease, but it is important to recognize its characteristic endoscopic findings to make a diagnosis. © 2012 The Authors. Digestive Endoscopy © 2012 Japan Gastroenterological Endoscopy Society.

  15. Design of nano- and microfiber combined scaffolds by electrospinning of collagen onto starch-based fiber meshes: a man-made equivalent of natural extracellular matrix.

    Science.gov (United States)

    Tuzlakoglu, Kadriye; Santos, Marina I; Neves, Nuno; Reis, Rui L

    2011-02-01

    Mimicking the structural organization and biologic function of natural extracellular matrix has been one of the main goals of tissue engineering. Nevertheless, the majority of scaffolding materials for bone regeneration highlights biochemical functionality in detriment of mechanical properties. In this work we present a rather innovative construct that combines in the same structure electrospun type I collagen nanofibers with starch-based microfibers. These combined structures were obtained by a two-step methodology and structurally consist in a type I collagen nano-network incorporated on a macro starch-based support. The morphology of the developed structures was assessed by several microscopy techniques and the collagenous nature of the nano-network was confirmed by immunohistochemistry. In addition, and especially regarding the requirements of large bone defects, we also successfully introduced the concept of layer by layer, as a way to produce thicker structures. In an attempt to recreate bone microenvironment, the design and biochemical composition of the combined structures also envisioned bone-forming cells and endothelial cells (ECs). The inclusion of a type I collagen nano-network induced a stretched morphology and improved the metabolic activity of osteoblasts. Regarding ECs, the presence of type I collagen on the combined structures provided adhesive support and obviated the need of precoating with fibronectin. It was also importantly observed that ECs on the nano-network organized into circular structures, a three-dimensional arrangement distinct from that observed for osteoblasts and resembling the microcappillary-like organizations formed during angiogenesis. By providing simultaneously physical and chemical cues for cells, the herein-proposed combined structures hold a great potential in bone regeneration as a man-made equivalent of extracellular matrix.

  16. The study on separation and purification of apigenin using collagen fiber adsorbent%胶原纤维吸附剂对芹菜素的分离纯化性能研究

    Institute of Scientific and Technical Information of China (English)

    张琦弦; 张文华; 廖学品; 石碧

    2012-01-01

    Collagen fiber, cross-linked by glutaraldehyde, was used as an adsorbent for the chromatographic separation and purification of apigenin from the mixture of flavonoids of apigenin, quercetin and myricetin. It was found that the collagen fiber adsorbent shows difference on adsorption ability to apigenin, quercetin and myricetin. The adsorption capacity of apigenin is relatively lowest. Apigenin could be well separated from the mixture by stepwise elution using 100Y0-70% aqueous ethanol solutions, and its purity was 98.03% and the recovery extent was 100%. While the apigenin and quercetin could be separated from the mixture system by stepwise elution using 40%-60% aqueous ethanol solutions, and their purity was 99.16% and 99.47%, and the recovery extent was 100K and 91.22%, respectively. It was also found that increasing the column heignt is helpful to improve the purity of apigenin. In addition, the separation capability of collagen fiber adsorbent was not obviously reduced after 5 times of repeated applications, exhibiting good reusability. Therefore, the collagen fiber adsorbent can be used for the effective separation and purification of apigenin from the mixture of flavonoids.%以戊二醛交联胶原纤维为吸附剂,通过柱层析研究其对芹菜素、槲皮素和杨梅素组成的三元黄酮类混合物中芹菜素的分离纯化特性。结果表明胶原纤维吸附剂对3种黄酮化合物表现出一定的吸附差异,对芹菜素的吸附作用最小;用100%~70%乙醇水溶液分步淋洗,能够从混合物中分离得到芹菜素,其纯度为98.03%,回收率为100%;用40%~60%乙醇水溶液分步淋洗,能够分离得到芹菜素和槲皮素,产物纯度分别为99.16%和99.47%,回收率分别为100%和91.22%;适当增大吸附柱的柱高,有助于提高芹菜素的纯度;在5次重复分离实验中,胶原纤维吸附剂的分离性能无明显降低,具有较好的重复使用性。因此,胶原纤维吸附剂可用于黄酮类混合物中芹菜素的分离纯化。

  17. Effects of Heating and Frozen Storage on Ultrastructure of Collagen Fibers from Chicken Claw%加热和冻藏对鸡爪胶原纤维超微结构的影响

    Institute of Scientific and Technical Information of China (English)

    高伟伟; 霍香如; 李桂霞; 韦永可; 朱杰

    2015-01-01

    The main objective of this study was to explore the effects of different temperatures and treatment times on ultrastructure of collagen fibers from chicken claw. In the heated group, fresh samples were heated in water of 50, 60 and 70℃ for 10, 20 and 30 minutes respectively; in the frozen group, samples were frozen in−20 and−80℃ for 5, 10 and 15 days respectively. By scanning the samples via atomic force microscopes, the experiment was intended to examine the changes inD-spacing length and roughness of collagen fiber under different treatments. The results show that with the heating temperature rising and processing time becoming longer, theD-spacing length of collagen fiber grew shorter, and it grew longer when the frozen temperature decreased and storage time was extended. Samples at 60 and−20℃ showed the most significant changes. At 60℃,D-spacing length reduced from (72.20±2.58) to (71.00±1.78) nm (n =10) with processing time increasing from 10 to 30 min; at−20℃, it increased from (69.70±2.60) to (73.00±2.90) nm (n =10) as storage time increased from 5 to 15 days.With the frozen time increasing, the surface roughness of collagen fibers from chicken claw increased. At 50℃, with the heating time increasing, the roughness increase firstly and then decrease. The contrary changes in roughness change were observed for heating at 60℃.%研究不同温度和时间条件处理对鸡爪筋胶原纤维超微结构的影响。加热组将新鲜鸡爪筋剪碎匀浆后分别在50、60、70℃条件下水浴加热10、20、30 min;冻藏组将新鲜鸡爪筋分别在-20、-80℃条件下冻藏5、10、15 d,通过对处理后的样品采用原子力显微镜扫描成像的方法研究鸡爪筋在不同温度及时间处理后的胶原纤维周期长度和粗糙度的变化。结果表明:胶原纤维周期长度随加热温度升高、加热时间增长而变短,随冻藏温度降低,冻藏时间的延长而变长,其中60、-20

  18. Collagen in Human Tissues: Structure, Function, and Biomedical Implications from a Tissue Engineering Perspective

    Science.gov (United States)

    Balasubramanian, Preethi; Prabhakaran, Molamma P.; Sireesha, Merum; Ramakrishna, Seeram

    The extracellular matrix is a complex biological structure encoded with various proteins, among which the collagen family is the most significant and abundant of all, contributing 30-35% of the whole-body protein. "Collagen" is a generic term for proteins that forms a triple-helical structure with three polypeptide chains, and around 29 types of collagen have been identified up to now. Although most of the members of the collagen family form such supramolecular structures, extensive diversity exists between each type of collagen. The diversity is not only based on the molecular assembly and supramolecular structures of collagen types but is also observed within its tissue distribution, function, and pathology. Collagens possess complex hierarchical structures and are present in various forms such as collagen fibrils (1.5-3.5 nm wide), collagen fibers (50-70 nm wide), and collagen bundles (150-250 nm wide), with distinct properties characteristic of each tissue providing elasticity to skin, softness of the cartilage, stiffness of the bone and tendon, transparency of the cornea, opaqueness of the sclera, etc. There exists an exclusive relation between the structural features of collagen in human tissues (such as the collagen composition, collagen fibril length and diameter, collagen distribution, and collagen fiber orientation) and its tissue-specific mechanical properties. In bone, a transverse collagen fiber orientation prevails in regions of higher compressive stress whereas longitudinally oriented collagen fibers correlate to higher tensile stress. The immense versatility of collagen compels a thorough understanding of the collagen types and this review discusses the major types of collagen found in different human tissues, highlighting their tissue-specific uniqueness based on their structure and mechanical function. The changes in collagen during a specific tissue damage or injury are discussed further, focusing on the many tissue engineering applications for

  19. 不同打浆度胶原纤维形态及抄片性质%The Morphology and Handsheets Behaviors of Collagen Fiber under Different Beating Degree

    Institute of Scientific and Technical Information of China (English)

    郭佩佩; 刘一山; 廖学品; 石碧

    2011-01-01

    采用机械方法分离制革废弃物的胶原纤维,并对其进行打浆处理,对不同打浆度的胶原纤维形态和抄片性能进行了研究。实验表明:打浆度在80°SR以上时,胶原纤维才能较好地分散;采用扫描电子显微镜及粒径统计法测定不同打浆度下(80°SR、85°SR、92°SR)胶原纤维的直径,发现纤维直径多分布在0.1gm左右,且随着打浆度的提高,纤维粗细更加均匀;通过湿重法间接表示纤维长度,实验表明在85°SR时纤维长度达到最大,后逐渐降低;随着打浆度的提高,抄片紧度、抗张强度和撕裂强度均增加,92°SR抄片的抗张和撕裂强度可分别%The waste leather from tannery was broken into pulp with mechanical pulping, and the morphology and handsheet behaviors of collagen fiber under different beating degree were studied.The experimental results indicated that the collagen fiber could be dispe

  20. Type XI Collagen

    DEFF Research Database (Denmark)

    Luo, Yunyun

    2016-01-01

    Type XI collagen is a fibrillary collagen. Type XI collagen is broadly distributed in articular cartilage, testis, trachea, tendons, trabecular bone, skeletal muscle, placenta, lung, and the neoepithelium of the brain. Type XI collagen is able to regulate fibrillogenesis by maintaining the spacing...... and diameter of type II collagen fibrils, and a nucleator for the fibrillogenesis of collagen types I and II. Mutations in type XI collagen are associated with Stickler syndrome, Marshall syndrome, fibrochondrogenesis, otospondylomegaepiphyseal dysplasia deafness, and Weissenbacher–Zweymüller syndrome. Type XI...... collagen binds heparin, heparan sulfate, and dermatan sulfate. Currently there are no biomarkers for type XI collagen....

  1. Discussion of Sound-Absorbing Paper Manufacturing by Using Vermiculite Powder and Collagen Fiber%蛭石粉和胶原纤维配抄吸音纸的探讨

    Institute of Scientific and Technical Information of China (English)

    罗英; 张美云; 刘正伟

    2011-01-01

    将具有吸音性能的蛭石粉作为填料,利用胶原纤维与植物纤维混合制备吸音纸,研究蛭石粉对吸音纸物理特性和吸音性能的影响,并分析纸页结构形态对吸音性能的影响。结果表明:蛭石粉的用量保持在15%左右,纸页性能变化较小;而且蛭石粉可以改善纸页的吸音性能,纸页结构更均匀,使其吸音性能稳定。%A new sound-absorbing paper was manufactured by using collagen fibers and plant fibers, sound-absorbing vermiculite powder as filler. The effects of the vermiculite powder on the paper physical characteristics and sound-absorbing efficiency were studied, and the effects of the paper structure on the sound-absorbing efficiency were discussed. The research results indicated: when the amount of vermiculite powder was about 15%, the paper performance was stable. Adding vermiculite powder could improve the sound-absorbing performance and make the paper structure uniformity, so the sound-absorbing ability becomes stable.

  2. Comparative performance of collagen nanofibers electrospun from different solvents and stabilized by different crosslinkers.

    Science.gov (United States)

    Fiorani, Andrea; Gualandi, Chiara; Panseri, Silvia; Montesi, Monica; Marcacci, Maurilio; Focarete, Maria Letizia; Bigi, Adriana

    2014-10-01

    Collagen electrospun scaffolds well reproduce the structure of the extracellular matrix (ECM) of natural tissues by coupling high biomimetism of the biological material with the fibrous morphology of the protein. Structural properties of collagen electrospun fibers are still a debated subject and there are conflicting reports in the literature addressing the presence of ultrastructure of collagen in electrospun fibers. In this work collagen type I was successfully electrospun from two different solvents, trifluoroethanol (TFE) and dilute acetic acid (AcOH). Characterization of collagen fibers was performed by means of SEM, ATR-IR, Circular Dichroism and WAXD. We demonstrated that collagen fibers contained a very low amount of triple helix with respect to pristine collagen (18 and 16% in fibers electrospun from AcOH and TFE, respectively) and that triple helix denaturation occurred during polymer dissolution. Collagen scaffolds were crosslinked by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), a commonly employed crosslinker for electrospun collagen, and 1,4-butanediol diglycidyl ether (BDDGE), that was tested for the first time in this work as crosslinking agent for collagen in the form of electrospun fibers. We demonstrated that BDDGE successfully crosslinked collagen and preserved at the same time the scaffold fibrous morphology, while scaffolds crosslinked with EDC completely lost their porous structure. Mesenchymal stem cell experiments demonstrated that collagen scaffolds crosslinked with BDDGE are biocompatible and support cell attachment.

  3. Design and structure of two HIV-1 clade C SOSIP.664 trimers that increase the arsenal of native-like Env immunogens.

    Science.gov (United States)

    Julien, Jean-Philippe; Lee, Jeong Hyun; Ozorowski, Gabriel; Hua, Yuanzi; Torrents de la Peña, Alba; de Taeye, Steven W; Nieusma, Travis; Cupo, Albert; Yasmeen, Anila; Golabek, Michael; Pugach, Pavel; Klasse, P J; Moore, John P; Sanders, Rogier W; Ward, Andrew B; Wilson, Ian A

    2015-09-22

    A key challenge in the quest toward an HIV-1 vaccine is design of immunogens that can generate a broadly neutralizing antibody (bnAb) response against the enormous sequence diversity of the HIV-1 envelope glycoprotein (Env). We previously demonstrated that a recombinant, soluble, fully cleaved SOSIP.664 trimer based on the clade A BG505 sequence is a faithful antigenic and structural mimic of the native trimer in its prefusion conformation. Here, we sought clade C native-like trimers with comparable properties. We identified DU422 and ZM197M SOSIP.664 trimers as being appropriately thermostable (Tm of 63.4 °C and 62.7 °C, respectively) and predominantly native-like, as determined by negative-stain electron microscopy (EM). Size exclusion chromatography, ELISA, and surface plasmon resonance further showed that these trimers properly display epitopes for all of the major bnAb classes, including quaternary-dependent, trimer-apex (e.g., PGT145) and gp120/gp41 interface (e.g., PGT151) epitopes. A cryo-EM reconstruction of the ZM197M SOSIP.664 trimer complexed with VRC01 Fab against the CD4 binding site at subnanometer resolution revealed a striking overall similarity to its BG505 counterpart with expected local conformational differences in the gp120 V1, V2, and V4 loops. These stable clade C trimers contribute additional diversity to the pool of native-like Env immunogens as key components of strategies to induce bnAbs to HIV-1.

  4. Raman spectroscopy and multivariate analysis for the rapid discrimination between native-like and non-native states in freeze-dried protein formulations.

    Science.gov (United States)

    Pieters, Sigrid; Vander Heyden, Yvan; Roger, Jean-Michel; D'Hondt, Matthias; Hansen, Laurent; Palagos, Bernard; De Spiegeleer, Bart; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2013-10-01

    This study investigates whether Raman spectroscopy combined with multivariate analysis (MVA) enables a rapid and direct differentiation between two classes of conformational states, i.e., native-like and non-native proteins, in freeze-dried formulations. A data set comprising of 99 spectra, both from native-like and various types of non-native freeze-dried protein formulations, was obtained by freeze-drying lactate dehydrogenase (LDH) as model protein under various conditions. Changes in the secondary structure in the solid freeze-dried proteins were determined through visual interpretation of the blank corrected second derivative amide I band in the ATR-FTIR spectra (further called FTIR spectra) and served as an independent reference to assign class labels. Exploratory analysis and supervised classification, using Principal Components Analysis (PCA) and Partial Least Squares - Linear Discriminant Analysis (PLS-LDA), respectively, revealed that Raman spectroscopy is with 95% accuracy able to correctly discriminate between native-like and non-native states in the tested freeze-dried LDH formulations. Backbone (i.e., amide III) and side chain sensitive spectral regions proved important for making the discrimination between both classes. As discrimination was not influenced by the spectral signals from the tested excipients, there was no need for blank corrections. The Raman model may allow direct and automated analysis of the investigated quality attribute, opening possibilities for a real time and in-line quality indication as a future step. However, the sensitivity of the method should be further investigated and where possible improved. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Identifying native-like protein structures with scoring functions based on all-atom ECEPP force fields, implicit solvent models and structure relaxation.

    Science.gov (United States)

    Arnautova, Yelena A; Vorobjev, Yury N; Vila, Jorge A; Scheraga, Harold A

    2009-10-01

    Availability of energy functions which can discriminate native-like from non-native protein conformations is crucial for theoretical protein structure prediction and refinement of low-resolution protein models. This article reports the results of benchmark tests for scoring functions based on two all-atom ECEPP force fields, that is, ECEPP/3 and ECEPP05, and two implicit solvent models for a large set of protein decoys. The following three scoring functions are considered: (i) ECEPP05 plus a solvent-accessible surface area model with the parameters optimized with a set of protein decoys (ECEPP05/SA); (ii) ECEPP/3 plus the solvent-accessible surface area model of Ooi et al. (Proc Natl Acad Sci USA 1987;84:3086-3090) (ECEPP3/OONS); and (iii) ECEPP05 plus an implicit solvent model based on a solution of the Poisson equation with an optimized Fast Adaptive Multigrid Boundary Element (FAMBEpH) method (ECEPP05/FAMBEpH). Short Monte Carlo-with-Minimization (MCM) simulations, following local energy minimization, are used as a scoring method with ECEPP05/SA and ECEPP3/OONS potentials, whereas energy calculation is used with ECEPP05/FAMBEpH. The performance of each scoring function is evaluated by examining its ability to distinguish between native-like and non-native protein structures. The results of the tests show that the new ECEPP05/SA scoring function represents a significant improvement over the earlier ECEPP3/OONS version of the force field. Thus, it is able to rank native-like structures with C(alpha) root-mean-square-deviations below 3.5 A as lowest-energy conformations for 76% and within the top 10 for 87% of the proteins tested, compared with 69 and 80%, respectively, for ECEPP3/OONS. The use of the FAMBEpH solvation model, which provides a more accurate description of the protein-solvent interactions, improves the discriminative ability of the scoring function to 89%. All failed tests in which the native-like structures cannot be discriminated as those with low

  6. SO2吸人对运动大鼠心肌胶原纤维形态特征及胶原蛋白含量的影响%Effects of Sulfur Dioxide Inhalation on Myocardial Collagen Fiber Morphology and Collagen Content in Exercising Rats

    Institute of Scientific and Technical Information of China (English)

    刘晓莉; 陈平; 乔德才

    2012-01-01

    Objective To investigate the effects of sulfur dioxide(SO2) inhalation on the myocardial collagen fiber morphology and collagen content of exercising rats. Methods Twenty-four SD rats were randomly divided into four groups: rest group (RG), exercise group (EG), SO2 exposure rest group (SRG) and SO2 exposure exercise group (SEG), six in each. The rats in SRG and SEG were put into the SO2 pollution environment. The rats in EG and SEG were trained in the motor driven wheel (8 m/min, 1 h/d for four consecutive weeks). Myocardial hydroxyproline content (HVP) was tested by stomach acid solution enzyme, and then calculated collagen concentration. The collagenous volume fraction (CVF) of cardiac muscle and surrounding of small arteries was measured by medical image analysis system. Results Myocardial hydroxyproline content and collagen concentration of SEG, SRG and EG rats increased significantly (P<0.05); SEG elevated more significantly (P<0.01). Collagen content of cardiac muscle and around small arteries in EG rats elevated slightly (P>0.05); CVR of heart muscle and small arteries in SRG and SEG rats significantly increased compared with RG (P<0.05); SEG rats increased significantly (P<0.01). Conclusion SO2 and exercise cause myocardial collagen fiber in rats excessive proliferation, collagen synthesis and degradation will be in imbalance, which may have adverse effects on myocardial intercellular transfer in force and normal cardiac diastolic and constructional function.%目的 探讨SO2吸入对运动大鼠心肌胶原纤维形态及胶原蛋白含量的影响.方法 24只雄性SD大鼠随机分为空白对照组、单纯运动组、单纯SO2污染组、SO2污染运动组,每组6只.单纯运动组、空白对照组大鼠置于自然环境中,单纯SO2污染组、SO2污染+运动组置于人工模拟的SO2污染环境中(10 mg/m3,1 h/d,连续4周),单纯运动组、SO2污染+运动组大鼠进行跑轮运动(8 m/min,1 h/d,连续4周).采用胃酶酸解法

  7. 以胶原纤维为炭源制备炭纤维负载钯纳米催化剂及其催化加氢特性%Preparation of Pd Nanoparticles Catalyst Supported by Carbon Fiber and Its Catalytic Hydrogenation Performance Investigation Using Collagen Fiber as Carbon Source

    Institute of Scientific and Technical Information of China (English)

    马骏; 毛卉; 廖洋; 廖学品; 石碧

    2013-01-01

    以胶原纤维为炭源,将胶原纤维接枝杨梅单宁(CF-BT)吸附Pd2+,经炭化及氢气还原后制备了炭纤维负载Pd纳米催化剂(Pd/C).通过场发射扫描电镜(FESEM)、透射电镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)等对该催化剂进行了表征.结果表明,所制备的Pd/C催化剂保留了胶原纤维规整的纤维状结构,Pd纳米粒子大小均匀且高度分散,平均粒径为2.92 nm.将该催化剂用于丙烯醇催化加氢反应,在308.0K和1.0 MPa氢压下,丙烯醇转化速率(TOF)高达2460 h-1,催化剂重复使用8次其催化活性基本不变,表现出了优良的重复使用性能.%At present investigation, collagen fiber was used as carbon source, and Pd2+ was first adsorbed on collagen fiber grafted with bayberry tannin (CF-BT) , and then the fibrous Pd/C was obtained after carbonization and reduction treatment . The as - prepared catalyst was characterized by FESEM, TEM, XRD and XPS. It was observed that the Pd/C catalyst was actually in the fibrous state which originate from collagen fiber. The Pd nanoparticles with an average diameter of 2.92 ran were finely dispersed in the catalysts. Subsequently, the Pd/C catalyst was utilized in hydrogenation of allyl alcohol for the estimation of its catalytic activity. The turnover frequency (TOF) of allyl alcohol was 2 460 h-1 at 308.0 K and 1.0 MPa pressure of H2. Moreover, the Pd/C catalyst exhibited excellent reusability, which can be reused 8 times without significant loss of catalytic activity.

  8. Collagen based magnetic nanocomposites for oil removal applications

    National Research Council Canada - National Science Library

    Thanikaivelan, Palanisamy; Narayanan, Narayanan T; Pradhan, Bhabendra K; Ajayan, Pulickel M

    2012-01-01

    ...) is prepared by a simple process utilizing protein wastes from leather industry. Molecular interaction between helical collagen fibers and spherical SPIONs is proven through calorimetric, microscopic and spectroscopic techniques...

  9. Collagen a natural scaffold for biology and engineering

    Science.gov (United States)

    Collagen, the most abundant protein in mammals, constitutes a quarter of the animal's total weight. The unique structure of fibrous collagens, a long triple helix that further associates into fibers, provides an insoluble scaffold that gives strength and form to the skin, tendons, bones, cornea and...

  10. Recombinant human-like collagen directed growth of hydroxyapatite nanocrystals

    Science.gov (United States)

    Zhai, Y.; Cui, F. Z.

    2006-05-01

    Bones are biocomposites with hierarchical structure that require controlled mineral deposition during their self-assembly to form tissues with unique mechanical properties. Type I collagen proteins, acidic extracellular matrix proteins, play a critical role in mineral formation and many researches on artificial bones have been made inspired by nature using type I collagen derived from animal tissues. Here we report that recombinant human-like type I collagen, an acidic protein, can direct growth of hydroxyapatite (HA) nanocrystals in vitro in the form of self-assembly of nano-fibrils of mineralized collagen resembling extracellular matrix. The mineralized collagen fibrils aligned parallel to each other to form mineralized collagen fibers. HA nanocrystals grew on the surface of these collagen fibrils with the c-axis of nanocrystals of HA orienting along the longitudinal axis of the fibrils. These artificial analogs of bone have a potential clinical application in bone repair.

  11. Fundamental insight into the effect of carbodiimide crosslinking on cellular recognition of collagen-based scaffolds.

    Science.gov (United States)

    Bax, Daniel V; Davidenko, Natalia; Gullberg, Donald; Hamaia, Samir W; Farndale, Richard W; Best, Serena M; Cameron, Ruth E

    2017-02-01

    Research on the development of collagen constructs is extremely important in the field of tissue engineering. Collagen scaffolds for numerous tissue engineering applications are frequently crosslinked with 1-ethyl-3-(3-dimethylaminopropyl-carbodiimide hydrochloride (EDC) in the presence of N-hydroxy-succinimide (NHS). Despite producing scaffolds with good biocompatibility and low cellular toxicity the influence of EDC/NHS crosslinking on the cell interactive properties of collagen has been overlooked. Here we have extensively studied the interaction of model cell lines with collagen I-based materials after crosslinking with different ratios of EDC in relation to the number of carboxylic acid residues on collagen. Divalent cation-dependent cell adhesion, via integrins α1β1, α2β1, α10β1 and α11β1, were sensitive to EDC crosslinking. With increasing EDC concentration, this was replaced with cation-independent adhesion. These results were replicated using purified recombinant I domains derived from integrin α1 and α2 subunits. Integrin α2β1-mediated cell spreading, apoptosis and proliferation were all heavily influenced by EDC crosslinking of collagen. Data from this rigorous study provides an exciting new insight that EDC/NHS crosslinking is utilising the same carboxylic side chain chemistry that is vital for native-like integrin-mediated cell interactions. Due to the ubiquitous usage of EDC/NHS crosslinked collagen for biomaterials fabrication this data is essential to have a full understanding in order to ensure optimized collagen-based material performance.

  12. Cataract-associated P23T γD-crystallin retains a native-like fold in amorphous-looking aggregates formed at physiological pH

    Science.gov (United States)

    Boatz, Jennifer C.; Whitley, Matthew J.; Li, Mingyue; Gronenborn, Angela M.; van der Wel, Patrick C. A.

    2017-05-01

    Cataracts cause vision loss through the large-scale aggregation of eye lens proteins as a result of ageing or congenital mutations. The development of new treatments is hindered by uncertainty about the nature of the aggregates and their mechanism of formation. We describe the structure and morphology of aggregates formed by the P23T human γD-crystallin mutant associated with congenital cataracts. At physiological pH, the protein forms aggregates that look amorphous and disordered by electron microscopy, reminiscent of the reported formation of amorphous deposits by other crystallin mutants. Surprisingly, solid-state NMR reveals that these amorphous deposits have a high degree of structural homogeneity at the atomic level and that the aggregated protein retains a native-like conformation, with no evidence for large-scale misfolding. Non-physiological destabilizing conditions used in many in vitro aggregation studies are shown to yield qualitatively different, highly misfolded amyloid-like fibrils.

  13. Differential Antibody Responses to Conserved HIV-1 Neutralizing Epitopes in the Context of Multivalent Scaffolds and Native-Like gp140 Trimers

    Science.gov (United States)

    Morris, Charles D.; Azadnia, Parisa; de Val, Natalia; Vora, Nemil; Honda, Andrew; Giang, Erick; Saye-Francisco, Karen; Cheng, Yushao; Lin, Xiaohe; Mann, Colin J.; Tang, Jeffrey; Sok, Devin; Burton, Dennis R.; Law, Mansun; Ward, Andrew B.

    2017-01-01

    ABSTRACT Broadly neutralizing antibodies (bNAbs) have provided valuable insights into the humoral immune response to HIV-1. While rationally designed epitope scaffolds and well-folded gp140 trimers have been proposed as vaccine antigens, a comparative understanding of their antibody responses has not yet been established. In this study, we probed antibody responses to the N332 supersite and the membrane-proximal external region (MPER) in the context of heterologous protein scaffolds and native-like gp140 trimers. Ferritin nanoparticles and fragment crystallizable (Fc) regions were utilized as multivalent carriers to display scaffold antigens with grafted N332 and MPER epitopes, respectively. Trimeric scaffolds were also identified to stabilize the MPER-containing BG505 gp140.681 trimer in a native-like conformation. Following structural and antigenic evaluation, a subset of scaffold and trimer antigens was selected for immunization in BALB/c mice. Serum binding revealed distinct patterns of antibody responses to these two bNAb targets presented in different structural contexts. For example, the N332 nanoparticles elicited glycan epitope-specific antibody responses that could also recognize the native trimer, while a scaffolded BG505 gp140.681 trimer generated a stronger and more rapid antibody response to the trimer apex than its parent gp140.664 trimer. Furthermore, next-generation sequencing (NGS) of mouse splenic B cells revealed expansion of antibody lineages with long heavy-chain complementarity-determining region 3 (HCDR3) loops upon activation by MPER scaffolds, in contrast to the steady repertoires primed by N332 nanoparticles and a soluble gp140.664 trimer. These findings will facilitate the future development of a coherent vaccination strategy that combines both epitope-focused and trimer-based approaches. PMID:28246356

  14. Isolation and Characterization of Collagen from Squid(Ommastreoges bartrami) Skin

    Institute of Scientific and Technical Information of China (English)

    YAN Mingyan; LI Bafang; ZHAO Xue

    2009-01-01

    Collagen of squid (Ommastrephes bartrami) skin was examined in the present study. Histology showed that collagen fiber in the skin was partially cross-linked with muscle fiber. Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin and characterized. The results of amino acid composition and electrophoretic patterns revealed that ASC and PSC were both type Ⅰ collagen, containing α1 and α2 chains. FTIR (fourier transform infrared spectroscopy) investigations con-firmed the existence of helical arrangements in PSC of squid skin. The denaturation temperature (Td) and shrinkage temperature (Ts)of PSC were 29.4℃ and 52.8℃, respectively.

  15. Development and utilization of a bovine type I collagen microfibril model

    Science.gov (United States)

    The structure of fibrous collagen, a long triple helix that self-associates in a staggered array to form a matrix of fibrils, fibers and fiber bundles, makes it uniquely suitable as a scaffold for biomaterial engineering. A major challenge for this application is to stabilize collagen structure by m...

  16. 苦味酸天狼猩红偏振光法检测阴茎白膜损伤愈合过程中胶原纤维类型分布的动态变化%Dynamic changes in type and distribution of collagen fibers healing using Picric-sirius red polarized light method

    Institute of Scientific and Technical Information of China (English)

    任鹏; 孙发; 李洪辉

    2009-01-01

    背景:阴茎白膜损伤修复过程中会发生一系列组织形态结构的病理改变,其胶原纤维等结构成分也必然产生相应变化.目的:构建新西兰兔阴茎白膜损伤动物模型,寻找一种简便、快捷、灵敏的观察阴茎白膜损伤愈合过程中胶原类型、分布动态变化的方法.设计、时间及地点:胶原纤维水平平的对比观察实验,于2005-06/2007-10在贵阳医学院组织工程实验室完成.材料:新西兰兔15只,均为雄性.方法:在兔阴茎背侧切除白膜5 mm×5 mm造成缺损制备兔阴茎白膜损伤模型,将切除的白膜原位缝合.分别在损伤后2,6,12周取阴茎白膜,每次5只,以苦味酸天狼猩红染色,应用偏振光显微镜观察.主要观察指标:阴茎白膜损伤愈合过程中胶原纤维面积的动态变化.结果:不同时间点同种纤维含量差异具有显著性意义(P<0.05).损伤后2周时,Ⅰ型和Ⅲ型胶原纤维共同存在,比例相当,胶原排列杂乱,相互交错.损伤后6周时,术区红色和黄色的Ⅰ型胶原纤维明显增加,Ⅲ型胶原纤维的比例下降,排列欠规律.到损伤后12周,粗大而鲜艳的红黄色Ⅰ型胶原成分占据了绝大部分,细小的绿色Ⅲ型胶原纤维数量急剧减少.结论:苦味酸天狼猩红偏振光法不仅能区分Ⅰ,Ⅲ型胶原的类型,还能清晰地显示Ⅰ,Ⅲ型胶原的形态、分布和比例关系,操作简单,特异性强.%BACKGROUND: Pathological changes of form and structure are induced in some tissues during repairing albuginea penis trauma, while structure and component of collagen fiber will be correspondingly changed necessarily.OBJECTIVE: To find a convenient, shortcut, and sensitive method to observe the dynamic change of type and distribution of collagen fiber during albuginea penis healing. DESIGN, TIME AND SETTING: A contrast study was performed at the Laboratory of Tissue Engineering, Guiyang Medical College between June 2005 and October 2007. MATERIALS

  17. 核心蛋白多糖调控真皮胶原纤维装配研究进展%Advances in the research of modulation of dermal collagen fibrin assembly by decorin

    Institute of Scientific and Technical Information of China (English)

    齐德清; 周跃; 张选奋

    2015-01-01

    Formation of dermal collagen fiber is a complicated and sequential process with the progressive assembly of collagen.Collagen monomers form stepped and orderly protofibrils through longitudinal displacement.Subsequently,protofibrils or protofibrils and collagen are bonded by covalent bonds to form orderly lamellar structure of collagen fibers.Then collagen fibers are tightly wound into coarse collagen fiber bundles by covalent crosslinking.Decorin is a multifunctional small leucinerich proteoglycan.It can prevent the aggregation of protofibrils by binding to the specific site of collagen with its core protein,and adjusting the spacing between the protofibrils with its glycosaminoglycan chain.Thus,by effecting the formation of collagen fibers with regulation of collagen assembly,decorin may help prevent scar formation and even promote regeneration.

  18. Collagen IV in Normal Skin and in Pathological Processes.

    Science.gov (United States)

    Abreu-Velez, Ana Maria; Howard, Michael S

    2012-01-01

    Type IV collagen is a type of collagen found primarily in the skin within the basement membrane zone. The type IV collagen C4 domain at the C-terminus is not removed in post-translational processing, and the fibers are thus link head-to-head, rather than in a parallel fashion. Also, type IV collagen lacks a glycine in every third amino-acid residue necessary for the tight collagen helix. Thus, the overall collagen-IV conformation is structurally more pliable and kinked, relative to other collagen subtypes. These structural features allow collagen IV to form sheets, which is the primary structural form found in the cutaneous basal lamina. There are six human genes associated with collagen IV, specifically COL4A1, COL4A2, COL4A3, COL4A4, COL4A5 and COL4A6. The aim of this review is to highlight the significance of this protein in normal skin, and in selected diseases. The alpha 3 protein constituent of type IV collagen is thought to be the antigen implicated in Goodpasture's syndrome, wherein the immune system attacks the basement membranes of the renal glomeruli and pulmonary alveoli. In addition, mutations to the genes coding for type IV collagen lead to the Alport syndrome. Furthermore, autoantibodies directed against denatured human type IV collagen have been described in rheumatoid arthritis, scleroderma, and SLE. Structural studies of collagen IV have been utilized to differentiate between subepidermal blistering diseases, including bullous pemphigoid, acquired epidermolysis bullosa, anti-epiligrin cicatricial pemphigoid, and bullous lupus erythematosus. Collagen IV is also of importance in wound healing and in embryogenesis. Pathological studies have demonstrated that minor structural differences in collagen IV can lead to distinct, clinically different diseases.

  19. Collagen IV in normal skin and in pathological processes

    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu-Velez

    2012-01-01

    Full Text Available Context: Type IV collagen is a type of collagen found primarily in the skin within the basement membrane zone. The type IV collagen C4 domain at the C-terminus is not removed in post-translational processing, and the fibers are thus link head-to-head, rather than in a parallel fashion. Also, type IV collagen lacks a glycine in every third amino-acid residue necessary for the tight collagen helix. Thus, the overall collagen-IV conformation is structurally more pliable and kinked, relative to other collagen subtypes. These structural features allow collagen IV to form sheets, which is the primary structural form found in the cutaneous basal lamina. There are six human genes associated with collagen IV, specifically COL4A1, COL4A2, COL4A3, COL4A4, COL4A5 and COL4A6. The aim of this review is to highlight the significance of this protein in normal skin, and in selected diseases. Results: The alpha 3 protein constituent of type IV collagen is thought to be the antigen implicated in Goodpasture′s syndrome, wherein the immune system attacks the basement membranes of the renal glomeruli and pulmonary alveoli. In addition, mutations to the genes coding for type IV collagen lead to the Alport syndrome. Furthermore, autoantibodies directed against denatured human type IV collagen have been described in rheumatoid arthritis, scleroderma, and SLE. Structural studies of collagen IV have been utilized to differentiate between subepidermal blistering diseases, including bullous pemphigoid, acquired epidermolysis bullosa, anti-epiligrin cicatricial pemphigoid, and bullous lupus erythematosus. Collagen IV is also of importance in wound healing and in embryogenesis. Conclusions: Pathological studies have demonstrated that minor structural differences in collagen IV can lead to distinct, clinically different diseases.

  20. Biomedical applications of collagens.

    Science.gov (United States)

    Ramshaw, John A M

    2016-05-01

    Collagen-based biomedical materials have developed into important, clinically effective materials used in a range of devices that have gained wide acceptance. These devices come with collagen in various formats, including those based on stabilized natural tissues, those that are based on extracted and purified collagens, and designed composite, biosynthetic materials. Further knowledge on the structure and function of collagens has led to on-going developments and improvements. Among these developments has been the production of recombinant collagen materials that are well defined and are disease free. Most recently, a group of bacterial, non-animal collagens has emerged that may provide an excellent, novel source of collagen for use in biomaterials and other applications. These newer collagens are discussed in detail. They can be modified to direct their function, and they can be fabricated into various formats, including films and sponges, while solutions can also be adapted for use in surface coating technologies.

  1. Collagen vascular disease

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/001223.htm Collagen vascular disease To use the sharing features on this ... previously said to have "connective tissue" or "collagen vascular" disease. We now have names for many specific ...

  2. Picrosirius red staining assessment of collagen after dermal roller application: A minimally invasive percutaneous collagen induction therapy

    Directory of Open Access Journals (Sweden)

    Fatma El-Zahraa Salah El-Deen Yassin

    2014-01-01

    Full Text Available Background: Percutaneous collagen induction (PCI through dermal roller breaks old collagen strands, promotes removal of damaged collagen and induces more collagen formation. Collagen fibers can be assessed by traditional stains or by polarized light assessment of Picrosirius red stain. Objective: The purpose of the current study is the clinical and histopathological evaluation of percutaneous collagen formation in atrophic acne scars after dermal roller application. Patients and Methods: Total study duration was 26 weeks in which 12 patients received seven sessions of PCI at 3-weeks interval, 3 mm punch biopsy specimens of scars were obtained before and after treatment (at 18 and 26 weeks. Microscopic examination of pre and post operative biopsies were done, using routine stains and Picrosirius red stain. Results: PCI induced notable improvement in the appearance of acne scars with significant reduction in the score from 123.3 ± 24.5 to 74.16 ± 16.49 (P = 0.00 after 26 weeks. Polarized light assessment of Picrosirius red stain clarified the gradual replacement of old thick orange-red birefringent collagen fibers by newly synthesized thin green-yellow birefringent ones postoperatively. Conclusion: Skin needling is a simple and minimally invasive procedure. The polarized light assessment of Picrosirius red stain clarified the change of the optical properties of collagen fibers according to the maturation process.

  3. Stabilization of collagen-model, triple-helical peptides for in vitro and in vivo applications.

    Science.gov (United States)

    Bhowmick, Manishabrata; Fields, Gregg B

    2013-01-01

    The triple-helical structure of collagen has been accurately reproduced in numerous chemical and recombinant model systems. Triple-helical peptides and proteins have found application for dissecting collagen-stabilizing forces, isolating receptor- and protein-binding sites in collagen, mechanistic examination of collagenolytic proteases, and development of novel biomaterials. Introduction of native-like sequences into triple-helical constructs can reduce the thermal stability of the triple-helix to below that of the physiological environment. In turn, incorporation of nonnative amino acids and/or templates can enhance triple-helix stability. We presently describe approaches by which triple-helical structure can be modulated for use under physiological or near-physiological conditions.

  4. Mechanisms of lamellar collagen formation in connective tissues.

    Science.gov (United States)

    Ghazanfari, Samaneh; Khademhosseini, Ali; Smit, Theodoor H

    2016-08-01

    The objective of tissue engineering is to regenerate functional tissues. Engineering functional tissues requires an understanding of the mechanisms that guide the formation and evolution of structure in the extracellular matrix (ECM). In particular, the three-dimensional (3D) collagen fiber arrangement is important as it is the key structural determinant that provides mechanical integrity and biological function. In this review, we survey the current knowledge on collagen organization mechanisms that can be applied to create well-structured functional lamellar tissues and in particular intervertebral disc and cornea. Thus far, the mechanisms behind the formation of cross-aligned collagen fibers in the lamellar structures is not fully understood. We start with cell-induced collagen alignment and strain-stabilization behavior mechanisms which can explain a single anisotropically aligned collagen fiber layer. These mechanisms may explain why there is anisotropy in a single layer in the first place. However, they cannot explain why a consecutive collagen layer is laid down with an alternating alignment. Therefore, we explored another mechanism, called liquid crystal phasing. While dense concentrations of collagen show such behavior, there is little evidence that the conditions for liquid crystal phasing are actually met in vivo. Instead, lysyl aldehyde-derived collagen cross-links have been found essential for correct lamellar matrix deposition. Furthermore, we suggest that supra-cellular (tissue-level) shear stress may be instrumental in the alignment of collagen fibers. Understanding the potential mechanisms behind the lamellar collagen structure in connective tissues will lead to further improvement of the regeneration strategies of functional complex lamellar tissues.

  5. Quantifying external and internal collagen organization from Stokes-vector-based second harmonic generation imaging polarimetry

    Science.gov (United States)

    Ávila, Francisco J.; del Barco, Oscar; Bueno, Juan M.

    2017-10-01

    Collagen organization has been analyzed at both external and internal scales by combining Stokes-vector polarimetry and second harmonic generation microscopy. A significant linear relationship between the diattenuation and the external collagen organization was found. The dominant orientation of the collagen fibers was found to run parallel to the axis of diattenuation. Information on the collagen chirality was obtained from the circular dichroism, which showed also a strong dependence with the internal collagen organization. The results show that certain polarimetric parameters might be useful to extract quantitative information and characterize collagen arrangement.

  6. Noninvasive Quantitative Imaging of Collagen Microstructure in Three-Dimensional Hydrogels Using High-Frequency Ultrasound

    OpenAIRE

    Mercado, Karla P.; Helguera, María; Hocking, Denise C.; Dalecki, Diane

    2015-01-01

    Collagen I is widely used as a natural component of biomaterials for both tissue engineering and regenerative medicine applications. The physical and biological properties of fibrillar collagens are strongly tied to variations in collagen fiber microstructure. The goal of this study was to develop the use of high-frequency quantitative ultrasound to assess collagen microstructure within three-dimensional (3D) hydrogels noninvasively and nondestructively. The integrated backscatter coefficient...

  7. 以Fe(Ⅲ)改性胶原纤维为载体固定过氧化氢酶%Immobilization of catalase on Fe (Ⅲ) modified collagen fiber

    Institute of Scientific and Technical Information of China (English)

    陈爽; 宋娜; 廖学品; 石碧

    2011-01-01

    将胶原纤维用三价铁改性后作为载体,通过戊二醛的交联作用将过氧化氢酶固定在该载体上.制备的固定化过氧化氢酶蛋白固载量为16.7 mg/g,酶活收率为35%.研究了固定化酶与自由酶的最适pH、最适温度、热稳定性、贮存稳定性及操作稳定性.结果表明:过氧化氢酶经此法固定化后,最适pH及最适温度与自由酶相同,分别为pH 7.0和25℃;但固定化酶的热稳定性显著提高,在75℃保存5 h后,仍能保留30%的活力,而自由酶则完全失活;固定化酶在室温下保存12 d后,酶活力仍保持在88%以上,而自由酶在此条件下则完全失活;此外,固定化过氧化氢酶还表现出了良好的操作稳定性,在室温下连续反应26次后,相对活力为57%.该研究表明胶原纤维可作为固定化过氧化%Fe (III) modified collagen fibers were used to immobilize catalase through the cross-linking of glutaraldehyde. The loading amount of catalase on the supporting matrix was 16.7 mg/g, and 35% enzymatic activity was remained. A series of experiments were conducted on free and immobilized catalase in order to investigate their optimal pH and temperature, and the thermal, storage and operation stability. Results suggest that the free and immobilized catalase prefer similar pH and temperature condition, which were pH 7.0 and 25 ℃. It should be noted that the thermal stability of catalase was considerably improved after immobilization owing to the fact that the enzyme kept 30% of relative activity after incubation at 75 ℃ for 5 h. On the contrary, the free catalase was completely inactive. As for the storage stability, the immobilized catalase kept 88% of relative activity after stored at room temperature for 12 days while the free one was completely inactive under the same conditions. Moreover, the immobilized catalase preserved 57% of relative activity after being reused 26 times, exhibiting excellent operation stability. Consequently

  8. Differential binding of neutralizing and non-neutralizing antibodies to native-like soluble HIV-1 Env trimers, uncleaved Env proteins, and monomeric subunits.

    Science.gov (United States)

    Yasmeen, Anila; Ringe, Rajesh; Derking, Ronald; Cupo, Albert; Julien, Jean-Philippe; Burton, Dennis R; Ward, Andrew B; Wilson, Ian A; Sanders, Rogier W; Moore, John P; Klasse, Per Johan

    2014-05-29

    The trimeric envelope glycoproteins (Env) on the surface of HIV-1 virions are the targets for neutralizing antibodies (NAbs). No candidate HIV-1 immunogen has yet induced potent, broadly active NAbs (bNAbs). Part of the explanation may be that previously tested Env proteins inadequately mimic the functional, native Env complex. Trimerization and the proteolytic processing of Env precursors into gp120 and gp41 profoundly alter antigenicity, but soluble cleaved trimers are too unstable to serve as immunogens. By introducing stabilizing mutations (SOSIP), we constructed soluble, cleaved Env trimers derived from the HIV-1 subtype A isolate BG505 that resemble native Env spikes on virions both structurally and antigenically. We used surface plasmon resonance (SPR) to quantify antibody binding to different forms of BG505 Env: the proteolytically cleaved SOSIP.664 trimers, cleaved gp120-gp41ECTO protomers, and gp120 monomers. Non-NAbs to the CD4-binding site bound only marginally to the trimers but equally well to gp120-gp41ECTO protomers and gp120 monomers, whereas the bNAb VRC01, directed to the CD4bs, bound to all three forms. In contrast, bNAbs to V1V2 glycan-dependent epitopes bound preferentially (PG9 and PG16) or exclusively (PGT145) to trimers. We also explored the antigenic consequences of three different features of SOSIP.664 gp140 trimers: the engineered inter-subunit disulfide bond, the trimer-stabilizing I559P change in gp41ECTO, and proteolytic cleavage at the gp120-gp41ECTO junction. Each of these three features incrementally promoted native-like trimer antigenicity. We compared Fab and IgG versions of bNAbs and validated a bivalent model of IgG binding. The NAbs showed widely divergent binding kinetics and degrees of binding to native-like BG505 SOSIP.664. High off-rate constants and low stoichiometric estimates of NAb binding were associated with large amounts of residual infectivity after NAb neutralization of the corresponding BG505.T332N pseudovirus

  9. The collagen assisted self-assembly of silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Salhi, Billel; Vaurette, Francois; Grandidier, Bruno; Stievenard, Didier [IEMN, UMR8520, Department ISEN, 41 Boulevard Vauban, 59046 Lille Cedex (France); Melnyk, Oleg [IBL, UMR8161, Institut Pasteur de Lille, Universite de Lille Nord de France, 1 rue du Professeur Calmette, 59021 Lille (France); Coffinier, Yannick; Boukherroub, Rabah [IRI, USR3078, c/o IEMN, Cite Scientifique, BP60069, 59652 Villeneuve d' Ascq (France)], E-mail: didier.stievenard@isen.iemn.univ-lille1.fr

    2009-06-10

    The paper reports on self-assembly of silicon nanowire junctions assisted by protocollagen, a low cost soluble long fiber protein and precursor of collagen fibrils. First, the collagen was combed on an octadecyl-terminated silicon surface with gold electrodes. Then the combed surface was exposed to an aqueous suspension of silicon nanowires. In order to increase electrostatic interactions between the positively charged collagen and the nanowires, the nanowires were chemically modified with negatively charged sulfonate groups. The interaction of collagen with the sulfonated nanowires, which mimics the native collagen/heparin sulfate interaction, induced self-assembly of the nanowires localized between gold electrodes. The proof of concept for the formation of spontaneous electrode-nanowire-electrode junctions using collagen as a template was supported by current-voltage measurements.

  10. Gap Dependent Rheology in Type I Collagen Gels

    Science.gov (United States)

    Arevalo, Richard; Urbach, Jeffrey; Blair, Daniel

    2010-03-01

    Branched type I collagen fiber networks provide extracellular support in mammalian tissues. The intricate network structure can succumb to partial or complete tearing under sufficient applied strain. Under small shear strains, in vitro collagen gels exhibit strain-stiffening while maintaining overall network integrity. Higher shear strains lead to network failure through discrete yielding events. We perform rheology and confocal-rheology experiments to fully elucidate the strain-stiffening and yielding behavior in these highly nonlinear materials. We apply continuous shear strains to collagen gels confined within the rheometer at fixed gaps. We observe that sheared collagen in the strain-stiffening and yielding regime has an apparent modulus that is strongly dependent on the collagen thickness. Moreover, we demonstrate that network yielding is universally controlled by the ratio of the collagen thickness to the mesh size. These results have broad implications for the interpretation of rheological data of extracellular matrix proteins and for the design of biomimetic scaffolds.

  11. The non-phagocytic route of collagen uptake

    DEFF Research Database (Denmark)

    Madsen, Daniel H; Ingvarsen, Signe; Jürgensen, Henrik J

    2011-01-01

    The degradation of collagens, the most abundant proteins of the extracellular matrix, is involved in numerous physiological and pathological conditions including cancer invasion. An important turnover pathway involves cellular internalization and degradation of large, soluble collagen fragments......, generated by initial cleavage of the insoluble collagen fibers. We have previously observed that in primary mouse fibroblasts, this endocytosis of collagen fragments is dependent on the receptor urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180. Others have identified additional......-regulates the receptor protein level on treated cells, to examine the role of uPARAP/Endo180 as a mediator of collagen internalization by a wide range of cultured cell types. With the exception of macrophages, all cells that proved capable of efficient collagen internalization were of mesenchymal origin and all...

  12. Long Range Force Transmission in Fibrous Matrices Enabled by Tension-Driven Alignment of Fibers

    CERN Document Server

    Wang, Hailong; Chen, Christopher S; Wells, Rebecca G; Shenoy, Vivek B

    2014-01-01

    Cells can sense and respond to mechanical signals over relatively long distances across fibrous extracellular matrices. Here, we explore all of the key factors that influence long range force transmission in cell-populated collagen matrices: alignment of collagen fibers, responses to applied force, strain stiffening properties of the aligned fibers, aspect ratios of the cells, and the polarization of cellular contraction. A constitutive law accounting for mechanically-driven collagen fiber reorientation is proposed. We systematically investigate the range of collagen fiber alignment using both finite element simulations and analytical calculations. Our results show that tension-driven collagen fiber alignment plays a crucial role in force transmission. Small critical stretch for fiber alignment, large fiber stiffness and fiber strain hardening behavior enable long-range interaction. Furthermore, the range of collagen fiber alignment for elliptical cells with polarized contraction is much larger than that for ...

  13. PGA-incorporated collagen: Toward a biodegradable composite scaffold for bone-tissue engineering.

    Science.gov (United States)

    Toosi, Shirin; Naderi-Meshkin, Hojjat; Kalalinia, Fatemeh; Peivandi, Mohammad Taghi; HosseinKhani, Hossein; Bahrami, Ahmad Reza; Heirani-Tabasi, Asieh; Mirahmadi, Mahdi; Behravan, Javad

    2016-08-01

    Nowadays composite scaffolds based on synthetic and natural biomaterials have got attention to increase healing of non-union bone fractures. To this end, different aspects of collagen sponge incorporated with poly(glycolic acid) (PGA) fiber were investigated in this study. Collagen solution (6.33 mg/mL) with PGA fibers (collagen/fiber ratio [w/w]: 4.22, 2.11, 1.06, 0.52) was freeze-dried, followed by dehydrothermal cross-linking to obtain collagen sponge incorporating PGA fibers. Properties of scaffold for cell viability, proliferation, and differentiation of mesenchymal stem cells (MSCs) were evaluated. Scanning electron microscopy showed that collagen sponge exhibited an interconnected pore structure with an average pore size of 190 μm, irrespective of PGA fiber incorporation. The collagen-PGA sponge was superior to the original collagen sponge in terms of the initial attachment, proliferation rate, and osteogenic differentiation of the bone marrow-MSCs (BM-MSC). The shrinkage of sponges during cell culture was significantly suppressed by fiber incorporation. Incorporation of PGA fiber is a simple and promising way to reinforce collagen sponge without impairing biocompatibility. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2020-2028, 2016.

  14. Deformation-dependent enzyme mechanokinetic cleavage of type I collagen.

    Science.gov (United States)

    Wyatt, Karla E-K; Bourne, Jonathan W; Torzilli, Peter A

    2009-05-01

    Collagen is a key structural protein in the extracellular matrix of many tissues. It provides biological tissues with tensile mechanical strength and is enzymatically cleaved by a class of matrix metalloproteinases known as collagenases. Collagen enzymatic kinetics has been well characterized in solubilized, gel, and reconstituted forms. However, limited information exists on enzyme degradation of structurally intact collagen fibers and, more importantly, on the effect of mechanical deformation on collagen cleavage. We studied the degradation of native rat tail tendon fibers by collagenase after the fibers were mechanically elongated to strains of epsilon=1-10%. After the fibers were elongated and the stress was allowed to relax, the fiber was immersed in Clostridium histolyticum collagenase and the decrease in stress (sigma) was monitored as a means of calculating the rate of enzyme cleavage of the fiber. An enzyme mechanokinetic (EMK) relaxation function T(E)(epsilon) in s(-1) was calculated from the linear stress-time response during fiber cleavage, where T(E)(epsilon) corresponds to the zero order Michaelis-Menten enzyme-substrate kinetic response. The EMK relaxation function T(E)(epsilon) was found to decrease with applied strain at a rate of approximately 9% per percent strain, with complete inhibition of collagen cleavage predicted to occur at a strain of approximately 11%. However, comparison of the EMK response (T(E) versus epsilon) to collagen's stress-strain response (sigma versus epsilon) suggested the possibility of three different EMK responses: (1) constant T(E)(epsilon) within the toe region (epsiloncollagen triple helix may be by a conformational change in the triple helix since the decrease in T(E)(epsilon) appeared concomitant with stretching of the collagen molecule.

  15. Pregnancy-induced remodeling of collagen architecture and content in the mitral valve.

    Science.gov (United States)

    Pierlot, Caitlin M; Lee, J Michael; Amini, Rouzbeh; Sacks, Michael S; Wells, Sarah M

    2014-10-01

    Pregnancy produces rapid, non-pathological volume-overload in the maternal circulation due to the demands of the growing fetus. Using a bovine model for human pregnancy, previous work in our laboratory has shown remarkable pregnancy-induced changes in leaflet size and mechanics of the mitral valve. The present study sought to relate these changes to structural alterations in the collagenous leaflet matrix. Anterior mitral valve leaflets were harvested from non-pregnant heifers and pregnant cows (pregnancy stage estimated by fetal length). We measured changes in the thickness of the leaflet and its anatomic layers via Verhoeff-Van Gieson staining, and in collagen crimp (wavelength and percent collagen crimped) via picrosirius red staining and polarized microscopy. Collagen concentration was determined biochemically: hydroxyproline assay for total collagen and pepsin-acid extraction for uncrosslinked collagen. Small-angle light scattering (SALS) assessed changes in internal fiber architecture (characterized by degree of fiber alignment and preferred fiber direction). Pregnancy produced significant changes to collagen structure in the mitral valve. Fiber alignment decreased 17% with an 11.5° rotation of fiber orientation toward the radial axis. Collagen fiber crimp was dramatically lost, accompanied by a 53% thickening of the fibrosa, and a 16% increase in total collagen concentration, both suggesting that new collagen is being synthesized. Extractable collagen concentration was low, both in the non-pregnant and pregnant state, suggesting early crosslinking of newly-synthesized collagen. This study has shown that the mitral valve is strongly adaptive during pregnancy, with significant changes in size, collagen content and architecture in response to rapidly changing demands.

  16. Endocytic collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H.; Jürgensen, Henrik J.; Ingvarsen, Signe;

    2012-01-01

    it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked......Fibrosis of the liver and its end-stage, cirrhosis, represent major health problems worldwide. In these fibrotic conditions, activated fibroblasts and hepatic stellate cells display a net deposition of collagen. This collagen deposition is a major factor leading to liver dysfunction, thus making...... up-regulation of uPARAP/Endo180 in activated fibroblasts and hepatic stellate cells located close to the collagen deposits. In a hepatic stellate cell line, uPARAP/Endo180 was shown to be active in, and required for, the uptake and intracellular degradation of collagen. To evaluate the functional...

  17. Complications of collagenous colitis

    Institute of Scientific and Technical Information of China (English)

    Hugh James Freeman

    2008-01-01

    Microscopic forms of colitis have been described, including collagenous colitis. This disorder generally has an apparently benign clinical course. However, a number of gastric and intestinal complications, possibly coincidental, may develop with collagenous colitis. Distinctive inflammatory disorders of the gastric mucosa have been described, including lymphocytic gastritis and collagenous gastritis. Celiac disease and collagenous sprue (or collagenous enteritis) may occur. Colonic ulceration has been associated with use of nonsteroidal anti-inflammatory drugs, while other forms of inflammatory bowel disease, including ulcerative colitis and Crohn's disease, may evolve from collagenous colitis. Submucosal "dissection", colonic fractures or mucosal tears and perforation from air insufflation during colonoscopy may occur and has been hypothesized to be due to compromise of the colonic wall from submucosal collagen deposition. Similar changes may result from increased intraluminal pressure during barium enema contrast studies. Finally, malignant disorders have also been reported, including carcinoma and lymphoproliferative disease.

  18. Spontaneous stacking of purple membranes during immobilization with physical cross-linked poly(vinyl alcohol) hydrogel with retaining native-like functionality of bacteriorhodopsin

    Science.gov (United States)

    Yokoyama, Yasunori; Tanaka, Hikaru; Yano, Shunsuke; Takahashi, Hiroshi; Kikukawa, Takashi; Sonoyama, Masashi; Takenaka, Koshi

    2017-05-01

    We previously discovered the correlation between light-induced chromophore color change of a photo-receptor membrane protein bacteriorhodopsin (bR) and its two-dimensional crystalline state in the membrane. To apply this phenomenon to a novel optical memory device, it is necessary that bR molecules are immobilized as maintaining their structure and functional properties. In this work, a poly(vinyl alcohol) (PVA) hydrogel with physical cross-linkages (hydrogen bonds between PVA chains) that resulted from repeated freezing-and-thawing (FT) cycles was used as an immobilization medium. To investigate the effects of physically cross-linked PVA gelation on the structure and function of bR in purple membranes (PMs), spectroscopic techniques were employed against PM/PVA immobilized samples prepared with different FT cycle numbers. Visible circular dichroism spectroscopy strongly suggested PM stacking during gelation. X-ray diffraction data also indicated the PM stacking as well as its native-like crystalline lattice even after gelation. Time-resolved absorption spectroscopy showed that bR photocycle behaviors in PM/PVA immobilized samples were almost identical to that in suspension. These results suggested that a physically cross-linked PVA hydrogel is appropriate for immobilizing membrane proteins in terms of maintaining their structure and functionality.

  19. Structure of collagen-glycosaminoglycan matrix and the influence to its integrity and stability.

    Science.gov (United States)

    Bi, Yuying; Patra, Prabir; Faezipour, Miad

    2014-01-01

    Glycosaminoglycan (GAG) is a chain-like disaccharide that is linked to polypeptide core to connect two collagen fibrils/fibers and provide the intermolecular force in Collagen-GAG matrix (C-G matrix). Thus, the distribution of GAG in C-G matrix contributes to the integrity and mechanical properties of the matrix and related tissue. This paper analyzes the transverse isotropic distribution of GAG in C-G matrix. The angle of GAGs related to collagen fibrils is used as parameters to qualify the GAGs isotropic characteristic in both 3D and 2D rendering. Statistical results included that over one third of GAGs were perpendicular directed to collagen fibril with symmetrical distribution for both 3D matrix and 2D plane cross through collagen fibrils. The three factors tested in this paper: collagen radius, collagen distribution, and GAGs density, were not statistically significant for the strength of Collagen-GAG matrix in 3D rendering. However in 2D rendering, a significant factor found was the radius of collagen in matrix for the GAGs directed to orthogonal plane of Collagen-GAG matrix. Between two cross-section selected from Collagen-GAG matrix model, the plane cross through collagen fibrils was symmetrically distributed but the total percentage of perpendicular directed GAG was deducted by decreasing collagen radius. There were some symmetry features of GAGs angle distribution in selected 2D plane that passed through space between collagen fibrils, but most models showed multiple peaks in GAGs angle distribution. With less GAGs directed to perpendicular of collagen fibril, strength in collagen cross-section weakened. Collagen distribution was also a factor that influences GAGs angle distribution in 2D rendering. True hexagonal collagen packaging is reported in this paper to have less strength at collagen cross-section compared to quasi-hexagonal collagen arrangement. In this work focus is on GAGs matrix within the collagen and its relevance to anisotropy.

  20. Performance of collagen sponge as a 3-D scaffold for tooth-tissue engineering.

    Science.gov (United States)

    Sumita, Yoshinori; Honda, Masaki J; Ohara, Takayuki; Tsuchiya, Shuhei; Sagara, Hiroshi; Kagami, Hideaki; Ueda, Minoru

    2006-06-01

    Tooth structure can be regenerated by seeding dissociated tooth cells onto polyglycolic acid fiber mesh, although the success rate of tooth production is low. The present study was designed to compare the performance of collagen sponge with polyglycolic acid fiber mesh as a 3-D scaffold for tooth-tissue engineering. Porcine third molar teeth at the early stage of crown formation were enzymatically dissociated into single cells, and the heterogeneous cells were seeded onto collagen sponge or the polyglycolic acid fiber mesh scaffolds. Scaffolds were then cultured to evaluate cell adhesion and ALP activity in vitro. An in vivo analysis was performed by implanting the constructs into the omentum of immunocompromised rats and evaluating tooth production up to 25 weeks. After 24h, there were a significantly higher number of cells attached to the collagen sponge scaffold than the polyglycolic acid fiber mesh scaffold. Similarly, the ALP activity was significantly higher for the collagen sponge scaffold was than the polyglycolic acid fiber mesh scaffold after 7 days of culture. The area of calcified tissue formed in the collagen sponge scaffold was also larger than in the polyglycolic acid fiber mesh scaffold. The results from in vivo experiments show conclusively that a collagen sponge scaffold allows tooth production with a higher degree of success than polyglycolic acid fiber mesh. Taken together, the results from this study show that collagen sponge scaffold is superior to the polyglycolic acid fiber mesh scaffold for tooth-tissue engineering.

  1. Collagens and proteoglycans of the corneal extracellular matrix

    Directory of Open Access Journals (Sweden)

    Y.M. Michelacci

    2003-08-01

    Full Text Available The cornea is a curved and transparent structure that provides the initial focusing of a light image into the eye. It consists of a central stroma that constitutes 90% of the corneal depth, covered anteriorly with epithelium and posteriorly with endothelium. Its transparency is the result of the regular spacing of collagen fibers with remarkably uniform diameter and interfibrillar space. Corneal collagen is composed of heterotypic fibrils consisting of type I and type V collagen molecules. The cornea also contains unusually high amounts of type VI collagen, which form microfibrillar structures, FACIT collagens (XII and XIV, and other nonfibrillar collagens (XIII and XVIII. FACIT collagens and other molecules, such as leucine-rich repeat proteoglycans, play important roles in modifying the structure and function of collagen fibrils.Proteoglycans are macromolecules composed of a protein core with covalently linked glycosaminoglycan side chains. Four leucine-rich repeat proteoglycans are present in the extracellular matrix of corneal stroma: decorin, lumican, mimecan and keratocan. The first is a dermatan sulfate proteoglycan, and the other three are keratan sulfate proteoglycans. Experimental evidence indicates that the keratan sulfate proteoglycans are involved in the regulation of collagen fibril diameter, and dermatan sulfate proteoglycan participates in the control of interfibrillar spacing and in the lamellar adhesion properties of corneal collagens. Heparan sulfate proteoglycans are minor components of the cornea, and are synthesized mainly by epithelial cells. The effect of injuries on proteoglycan synthesis is discussed.

  2. 放射性肺损伤初期Ⅲ、Ⅳ型胶原的变化及氨溴索的影响%The change of Ⅲ, Ⅳ collagen fibers in early stage of radiation-induced lung injury in rats and effect of ambroxol to its

    Institute of Scientific and Technical Information of China (English)

    叶江枫; 袁名辉; 蒙育林

    2011-01-01

    Objective To explore change of Ⅲ, Ⅳ collagen fibers in early stage of radiation-induced lung injury in rats and the efficacy of ambroxol to its.Methods 46 SD female rats were randomly divided into control( C group), radiational injury group( R group)and treatment group after radiational injury (M group).Ambroxol was given to rats in treatment groups at a dose of 20 mg/kg-per day by injection into belly from seven days before radiation until the end of the experiment, The rats in other groups were injection into belly with the same amount of saline.Rats in R group and M group were exposed to thoracic radiation at a dose of 20 Gy by linear accelerator.Collagen Ⅲ ,collagen Ⅳ in rat blood serum and in alveolar lavage were measured by radioimmunoassay in the day of 1,2,3,4 after radiation.The data were analyzed by student's t teat.Results The amount of collagenfibers in blood serum from rots of R group increased significantly compared to C group on day 2,3,4( P <0.01 ).The change was obviously in M group compared to R group ( P <0.01 ).Collagen Ⅲ and Ⅳ fibers in alveolar lavage was no difference among three groups.Conclusions Collagenfibers in blood serum increased in the early stage after the lung was radiated.Ambroxol can influence the change of collagenfibers in blood serum.%目的 探讨放射性肺损伤初期Ⅲ、Ⅳ型胶原的变化及氨溴索对放射性肺损伤的治疗作用.方法 雌性SD大鼠46只随机分为正常对照组C,照射组R和治疗组M.照射组和治疗组给予直线加速器照射,照射剂量单次20 Gy/min,照射组于照射后当天给予生理盐水腹腔内注射,治疗组于照射后当天给予氨溴索20 mg/kg/d,直至实验结束.于照射后1、2、3、4 d取大鼠血清及肺灌洗液放免法测定Ⅲ、Ⅳ型胶原,数据用组间t检验.结果 照射后R组2、3、4 d血清Ⅲ型胶原较C组显著升高(P<0.01).M组较同期R组变化显著(P<0.01).肺灌洗液中Ⅲ/Ⅳ型胶原三组

  3. Avaliação das fibras colágenas de meniscos frescos e preservados em glicerina: estudo experimental em coelhos (Oryctolagus cuniculus Evaluation of the collagen fibers of the fresh meniscus and the meniscuses preserved in glycerine: experimental study in rabbits (Oryctolagus cuniculus

    Directory of Open Access Journals (Sweden)

    Liana M. Vilela

    2010-04-01

    Full Text Available No presente estudo foi avaliado o efeito da glicerina 98% sobre as fibras colágenas, arquitetura tecidual e o tamanho de meniscos mediais de coelhos da raça Nova Zelândia. Os meniscos foram separados em três grupos: (1 Grupo MF com meniscos frescos (grupo controle, (2 Grupo MG com meniscos preservados em glicerina 98% por 30 dias, e (3 Grupo MR com meniscos preservados em glicerina 98% por 30 dias e reidratados em NaCl 0,9%, por 12 horas. Os cortes histológicos foram corados com sirius red para identificação dos tipos de colágenos e observados em microscópio de luz polarizada, avaliando-se a concentração total de colágeno Tipo I e III e a disposição das fibras. Os meniscos frescos apresentaram significativamente maior concentração de fibras colágenas Tipo I e menor concentração de fibras colágenas Tipo III que os meniscos preservados (MG e MR; isto ocorreu devido à perda de água e conseqüente redução do tamanho dos meniscos e retração das fibras colágenas dos meniscos dos Grupos MG e MR; isto pode ter feito com que as fibras Tipo I, mais espessas e em maior quantidade, se tornassem mais evidentes do que as fibras colágenas Tipo III, que são mais delgadas e frágeis (fibrilas. Nos três grupos estudados, as fibras colágenas apresentaram-se de forma circunferencial, interpostas por fibras orientadas radialmente. Entretanto, nos grupos tratados (MG e MR foi observado, em pequenas áreas, leve desorganização das fibras colágenas, o que correspondeu a 42,8% e 14,3% dos meniscos, respectivamente. O grupo de meniscos em glicerina apresentou redução significativa (pIn the present study was evaluated the effect of 98% glycerin on the collagen fibers, tissue architecture and size of medial meniscuses of New Zealand rabbits. The animals were separated into three groups: (1 Group MF of fresh meniscus, (2 Group MG of meniscus preserved in glycerin for 30 days, and (3 Group MR of meniscus preserved in glycerin for 30 days

  4. Spatio-temporal modification of collagen scaffolds mediated by triple helical propensity.

    Science.gov (United States)

    Wang, Allen Y; Foss, Catherine A; Leong, Shirley; Mo, Xiao; Pomper, Martin G; Yu, Seungju M

    2008-07-01

    Functionalized collagen that incorporates exogenous compounds may offer new and improved biomaterials applications, especially in drug-delivery, multifunctional implants, and tissue engineering. To that end, we developed a specific and reversible collagen modification technique utilizing associative chain interactions between synthetic collagen mimetic peptide (CMP) [(ProHypGly) chi; Hyp = hydroxyproline] and type I collagen. Here we show temperature-dependent collagen binding and subsequent release of a series of CMPs with varying chain lengths indicating a triple helical propensity driven binding mechanism. The binding took place when melted, single-strand CMPs were allowed to fold while in contact with reconstituted type I collagens. The binding affinity is highly specific to collagen as labeled CMP bound to nanometer scale periodic positions on type I collagen fibers and could be used to selectively image collagens in ex vivo human liver tissue. When heated to physiological temperature, bound CMPs discharged from the collagen at a sustained rate that correlated with CMP's triple helical propensity, suggesting that sustainability is mediated by dynamic collagen-CMP interactions. We also report on the spatially defined modification of collagen film with linear and multi-arm poly(ethylene glycol)-CMP conjugates; at 37 degrees C, these PEG-CMP conjugates exhibited temporary cell repelling activity lasting up to 9 days. These results demonstrate new opportunities for targeting pathologic collagens for diagnostic or therapeutic applications and for fabricating multifunctional collagen coatings and scaffolds that can temporally and spatially control the behavior of cells associated with the collagen matrices.

  5. 胶原纤维为模板TiO2、Lax/TiO2纳米纤维的制备、表征及光催化活性研究%Collagen fiber as a template for mesoporous TiO2 and Lax/TiO2 nano-fibers:synthesis,characterization and photocatalytic activities

    Institute of Scientific and Technical Information of China (English)

    蔡莉

    2014-01-01

    以胶原纤维为模板分别负载钛(Ti4+)或钛(Ti4+)和镧(La3+),经高温煅烧制得介孔 TiO 2和Lax/TiO 2纳米纤维.通过场发射扫描电镜(FESEM)、N2吸附-脱附等温线、X 射线衍射(XRD)、分子荧光光谱(PL)和紫外-可见吸收光谱(UV-Vis)等对这2类纳米纤维的结构和物理性能进行了表征.结果表明胶原纤维的纤维状结构能被较好地保留在TiO 2和 Lax/TiO 2纳米纤维中.TiO 2和 Lax/TiO 2纳米纤维的 N2吸附-脱附等温线属于典型的Ⅳ型,表明其具有介孔结构.XRD 分析表明,La3+的掺杂减小了 TiO 2的晶粒尺寸.与 Degussa P25相比,介孔TiO 2和 Lax/TiO 2(x ≤0.02)纳米纤维的紫外-可见吸收光谱红移,分子荧光光谱强度明显减弱.以孔雀石绿的光催化降解为模型反应,在可见光和紫外光激发下,介孔 TiO 2和 Lax/TiO 2纳米纤维的光催化活性均高于 Degussa P25.此外,Lax/TiO 2在可见光激发下的光催化活性高于未掺杂的 TiO 2纳米纤维.%Mesoporous TiO 2 and Lax/TiO 2 nano-fiber were prepared by loading titanium (Ti4+ ),or titanium (Ti4+ )and lanthanum (La3 + )on collagen fiber template,respectively,and then heat treated.The physico-chemical properties of these nano-fibers were fully characterized by means of field emission scanning electron microscopy (FESEM),N2 adsorption-desorption,X-ray diffraction (XRD),photoluminescence spectra (PL) and UV-Vis absorption spectra.It was found that the fibrous morphology of collagen fiber was well preserved in the TiO 2 and La0.02/TiO 2 nano-fibers.The N2 adsorption-desorption isotherms of TiO 2 and Lax/TiO 2 nano-fi-bers were the typical type Ⅳ,which associated with the characteristics of mesoporous materials.XRD analysis showed that La3 + doped into TiO 2 has a significant influence on crystal size of TiO 2 .Compared with Degussa P25,the TiO 2 and Lax/TiO 2 (x ≤0.02)nano-fibers showed a red-shift in their UV-Vis absorption spectra,and their PL spectra intensity

  6. 野黄芩苷对鼠舌癌移植瘤新生脉管及弹性和胶原纤维的影响%Effects of Scutellarin on New Vessel and Collagen and Elastic Fibers in Mouse Xenograft Model of Tongue Cancer

    Institute of Scientific and Technical Information of China (English)

    张丽娜; 郑金华; 李会平; 李海霞; 黄大勇; 高钟秀子; 崔海东

    2011-01-01

    Objective: To examine the effect of scutellarin on the expression of new vessel and the distribution of collagen and elastic fibers in mouse xenograft model of tongue squamous cancer cells (SAS). Methods: Tumor-inoculated nude mice were treated with various concentrations of scutellarin, normal saline, or cisplatin to observe the impact of scutellarin on tumor growth. The expression of vascular (labeled with CD105) and lymphatic (labeled with Prox-1) in the tumor were examined by immunohistochemistry. The distribution of collagen was assessed by Gomori's trichrome staining. And elastic fibers was assessed by Masson's trichrome stain. Results: The tumor volume treated with scutellarin was significantly reduced compared with the saline control group. The expression of new vascula and lymphatic were decreased. The elastic and collagen fibers within the tumor thickened, the number increased, and form many fibrous septa. Conclusion: In the present study we found 10mg/kg scutellarin can inhibit tumor growth in transplanted tongue cancer model, reduce the number of angiogenesis and lymphangiogenesis in tumor, and promote the morphological changes of elastic and collagen fibers, then prevent the spread and invasion of cancer.%目的:检测野黄芩苷对人舌鳞癌SAS细胞裸鼠移植瘤中的新生脉管及弹性和胶原纤维的表达和分布的影响,及对肿瘤生长的作用.方法:不同浓度的野黄芩苷、生理盐水及顺铂处理肿瘤,观察移植瘤体积的变化.结果:应用免疫组化观察CD105和Prox-1标记的血管和淋巴管的表达,Masson和醛品红染色检测弹性和胶原纤维的分布.野黄芩苷治疗组移植瘤体积、新生血管及淋巴管的数目较对照组明显减小;瘤内弹性和胶原纤维增粗增多并形成纤维隔.10 mg/kg的野黄芩苷能够有效抑制鼠舌癌移植瘤的生长,降低肿瘤新生血管和淋巴管的数量,且促使弹性及胶原纤维的形态布局的改变进一步阻止癌的侵袭和扩散.

  7. Pseudomembranous collagenous colitis.

    Science.gov (United States)

    Yuan, Shan; Reyes, Victoria; Bronner, Mary P

    2003-10-01

    The classic clinical and histologic features of collagenous colitis are well characterized; however, the acute or neutrophilic inflammatory changes that may accompany this entity are less well established. In this report of 10 patients, we describe the first series of pseudomembranous collagenous colitis. Because superimposed Clostridium difficile infection was only demonstrated in one patient and no other causes of pseudomembranous colitis were evident in the remaining nine patients, we conclude that pseudomembranes are part of the spectrum of collagenous colitis itself. This case series illustrates the importance of searching for collagenous colitis in the evaluation of pseudomembranous colitis. At the same time, superimposed infectious or ischemic etiologies need to be excluded clinically in any patient with superimposed pseudomembranes. The existence of pseudomembranes in collagenous colitis also lends support to the hypothesis that toxin- and/or ischemia-mediated injury may be involved in the pathogenesis of collagenous colitis.

  8. Myocardial Tissue Engineering With Cells Derived From Human-Induced Pluripotent Stem Cells and a Native-Like, High-Resolution, 3-Dimensionally Printed Scaffold.

    Science.gov (United States)

    Gao, Ling; Kupfer, Molly E; Jung, Jangwook P; Yang, Libang; Zhang, Patrick; Da Sie, Yong; Tran, Quyen; Ajeti, Visar; Freeman, Brian T; Fast, Vladimir G; Campagnola, Paul J; Ogle, Brenda M; Zhang, Jianyi

    2017-04-14

    Conventional 3-dimensional (3D) printing techniques cannot produce structures of the size at which individual cells interact. Here, we used multiphoton-excited 3D printing to generate a native-like extracellular matrix scaffold with submicron resolution and then seeded the scaffold with cardiomyocytes, smooth muscle cells, and endothelial cells that had been differentiated from human-induced pluripotent stem cells to generate a human-induced pluripotent stem cell-derived cardiac muscle patch (hCMP), which was subsequently evaluated in a murine model of myocardial infarction. The scaffold was seeded with ≈50 000 human-induced pluripotent stem cell-derived cardiomyocytes, smooth muscle cells, and endothelial cells (in a 2:1:1 ratio) to generate the hCMP, which began generating calcium transients and beating synchronously within 1 day of seeding; the speeds of contraction and relaxation and the peak amplitudes of the calcium transients increased significantly over the next 7 days. When tested in mice with surgically induced myocardial infarction, measurements of cardiac function, infarct size, apoptosis, both vascular and arteriole density, and cell proliferation at week 4 after treatment were significantly better in animals treated with the hCMPs than in animals treated with cell-free scaffolds, and the rate of cell engraftment in hCMP-treated animals was 24.5% at week 1 and 11.2% at week 4. Thus, the novel multiphoton-excited 3D printing technique produces extracellular matrix-based scaffolds with exceptional resolution and fidelity, and hCMPs fabricated with these scaffolds may significantly improve recovery from ischemic myocardial injury. © 2017 American Heart Association, Inc.

  9. The adsorption capacity of Pb2+ by waste collagen fiber spun-lace fabric tannins immobilized%单宁固化废鞣革胶原水刺布的 Pb2+吸附性能

    Institute of Scientific and Technical Information of China (English)

    赵继松; 殷保璞

    2014-01-01

    The waste leather was made into waste collagen fiber spun-lace fabric by textile manufacturing process. This kind of spun-lace fabric was then immobilized by tannin through the cross-link of glutaraldehyde. The structure and strength of the fabric were studied.Then the influences of initial Pb2+concentration, the temperature and pH value of the solution on the absorption of Pb2+have been studied.It shows that with the increase of these three parameters, adsorption of Pb2+increases,up to 25.95 mg/g.Finally, the fabric that has absorbed Pb2+was treated by 0.1 mol/L HCl solution to study its properties of de-sorption and performance of recycling.%将制革工业中的废弃皮革经过非织造工艺制成废鞣革胶原水刺布,通过戊二醛交联将单宁固化到废鞣革胶原水刺布上。首先研究单宁固化废鞣革胶原水刺布的形态结构及强伸性变化,然后分别研究Pb2+的初始浓度、溶液温度、溶液pH值对Pb2+吸附量的影响。结果表明:随着Pb2+的初始浓度、溶液温度、溶液pH值的增大,Pb2+的吸附量逐渐增大,最大为25.95 mg/g。最后利用0.1 mol/L稀HCl溶液对吸附材料进行解吸附试验,并讨论单宁固化废鞣革胶原水刺布吸附材料的解吸附性能及再生性。

  10. Studies on Structural Changes of Collagen in Silicosis

    Institute of Scientific and Technical Information of China (English)

    LIYU-RUI; HUXUN; 等

    1994-01-01

    In order to provide scientific information on the prevention and treatment of silicosis,studies about changes of silicotic collagen in lungs were carried out.In this paper,we present experiments about the structural changes of collagen in silicotic lungs of rats and patients.These included clectron microscopy,circular dichroism and infrared spectroscopy studies of collaeen fibers.The results indicated that fibers of silicotic collagen were shorter in length.smaller in diameter and decreased in α-helix content,The Si-O-R-group and -OH group were found increased and -C-C-backbone shortened.The increase of -Si-O-R-group indicated that silica formed linking bridgen between collagens whih may be the cause of progressive enlargement of nodules.

  11. SPARC and the N-propeptide of collagen I influence fibroblast proliferation and collagen assembly in the periodontal ligament

    Science.gov (United States)

    Trombetta-eSilva, Jessica; Hepfer, Glenn; Yao, Hai; Bradshaw, Amy Dodd

    2017-01-01

    The periodontal ligament (PDL) is a fibrous connective tissue that anchors tooth cementum into alveolar bone. Secreted protein acidic and rich in cysteine (SPARC) is a collagen-binding matricellular protein known to influence collagen fiber assembly in the PDL. In contrast, functional properties of the N-propeptide of collagen I, encoded in exon 2 of the COL1A1 gene, are poorly understood. In this study, the PDL of collagen I exon 2-deleted (wt/ko), SPARC-null (ko/wt), and double transgenic (ko/ko) mice were evaluated in terms of cellularity, collagen area, fiber morphology, and extraction force and compared to WT (wt/wt) mice. Picro sirius red staining indicated a decrease in total PDL collagen content in each of the transgenic mice compared to WT at 1 and 3 month age points. At 12 months, only SPARC-null (ko/wt) and double-null PDL demonstrated less total collagen versus WT. Likewise, an increase in thin PDL collagen fibers was observed at 1 and 3 months in each transgenic, with increases only in SPARC-null and double-null mice at 12 months. The force required for tooth extraction was significantly reduced in SPARC-null versus exon 2-deleted and WT mice, whereas double-null mice demonstrated further decreases in force required for tooth extraction. The number of proliferating fibroblasts and number and size of epithelial rests of Malassez were increased in each transgenic versus WT with double-null PDL exhibiting highest levels of proliferation and rests of Malassez at 1 month of age. Consistent with increases in PDL collagen in exon-2 deleted mice, with age, numbers of rests decreased at 12 months in this genotype. These results demonstrate for the first time a functional role of the N-propeptide in regulating collagen fiber assembly and cell behavior and suggest that SPARC and the N-propeptide of collagen I have distinct activities in regulating collagen fiber assembly and fibroblast function. PMID:28245286

  12. Pulse-modulated second harmonic imaging microscope quantitatively demonstrates marked increase of collagen in tumor after chemotherapy

    Science.gov (United States)

    Raja, Anju M.; Xu, Shuoyu; Sun, Wanxin; Zhou, Jianbiao; Tai, Dean C. S.; Chen, Chien-Shing; Rajapakse, Jagath C.; So, Peter T. C.; Yu, Hanry

    2010-09-01

    Pulse-modulated second harmonic imaging microscopes (PM-SHIMs) exhibit improved signal-to-noise ratio (SNR) over conventional SHIMs on sensitive imaging and quantification of weak collagen signals inside tissues. We quantify the spatial distribution of sparse collagen inside a xenograft model of human acute myeloid leukemia (AML) tumor specimens treated with a new drug against receptor tyrosine kinase (ABT-869), and observe a significant increase in collagen area percentage, collagen fiber length, fiber width, and fiber number after chemotherapy. This finding reveals new insights into tumor responses to chemotherapy and suggests caution in developing new drugs and therapeutic regimens against cancers.

  13. Getting to the heart of cardiac remodeling; how collagen subtypes may contribute to phenotype.

    Science.gov (United States)

    Collier, P; Watson, C J; van Es, M H; Phelan, D; McGorrian, C; Tolan, M; Ledwidge, M T; McDonald, K M; Baugh, J A

    2012-01-01

    The objective of this study was to investigate the nature and biomechanical properties of collagen fibers within the human myocardium. Targeting cardiac interstitial abnormalities will likely become a major focus of future preventative strategies with regard to the management of cardiac dysfunction. Current knowledge regarding the component structures of myocardial collagen networks is limited, further delineation of which will require application of more innovative technologies. We applied a novel methodology involving combined confocal laser scanning and atomic force microscopy to investigate myocardial collagen within ex-vivo right atrial tissue from 10 patients undergoing elective coronary bypass surgery. Immuno-fluorescent co-staining revealed discrete collagen I and III fibers. During single fiber deformation, overall median values of stiffness recorded in collagen III were 37±16% lower than in collagen I [pretraction, collagen I exhibited greater degrees of elastic recoil [patrial biopsies taken from patients in permanent atrial fibrillation (n=5) versus sinus rhythm (n=5), stiffness of both collagen fiber subtypes was augmented (patrial fibrillation compared to those in sinus rhythm are consistent with recent published findings of increased collagen cross-linking in this setting.

  14. Corneal collagen crosslinking for keratoconus. A review

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2014-10-01

    Full Text Available Photochemical crosslinking is widely applied in ophthalmology. Its biochemical effect is due to the release of singlet oxygen that promotes anaerobic photochemical reaction. Keratoconus is one of the most common corneal ectasia affecting 1 in 250 to 250 000 persons. Currently, the rate of iatrogenic ectasia following eximer laser refractive surgery increases due to biomechanical weakening of the cornea. Morphologically and biochemically, ectasia is characterized by corneal layers thinning, contact between the stroma and epithelium resulting from Bowman’s membrane rupture, chromatin fragmentation in keratocyte nuclei, phagocytosis, abnormal staining and arrangement of collagen fibers, enzyme system disorders, and keratocyte apoptosis. In corneal ectasia, altered enzymatic processes result in the synthesis of abnormal collagen. Collagen packing is determined by the activity of various extracellular matrix enzymes which bind amines and aldehydes of collagen fiber amino acids. In the late stage, morphological changes of Descemet’s membrane (i.e., rupture and detachment develop. Abnormal hexagonal-shaped keratocytes and their apoptosis are the signs of endothelial dystrophy. The lack of analogs in domestic ophthalmology encouraged the scientists of Ufa Eye Research Institute to develop a device for corneal collagen crosslinking. The parameters of ultraviolet (i.e., wavelength, exposure time, power to achieve the desired effect were identified. The specifics of some photosensitizers in the course of the procedure were studied. UFalink, a device for UV irradiation of cornea, and photosensitizer Dextralink were developed and adopted. Due to the high risk of endothelial damage, this treatment is contraindicated in severe keratoconus (CCT less than 400 microns. Major effects of corneal collagen crosslinking are the following: Young’s modulus (modulus of elasticity increase by 328.9 % (on average, temperature tolerance increase by 5

  15. Corneal collagen crosslinking for keratoconus. A review

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2014-01-01

    Full Text Available Photochemical crosslinking is widely applied in ophthalmology. Its biochemical effect is due to the release of singlet oxygen that promotes anaerobic photochemical reaction. Keratoconus is one of the most common corneal ectasia affecting 1 in 250 to 250 000 persons. Currently, the rate of iatrogenic ectasia following eximer laser refractive surgery increases due to biomechanical weakening of the cornea. Morphologically and biochemically, ectasia is characterized by corneal layers thinning, contact between the stroma and epithelium resulting from Bowman’s membrane rupture, chromatin fragmentation in keratocyte nuclei, phagocytosis, abnormal staining and arrangement of collagen fibers, enzyme system disorders, and keratocyte apoptosis. In corneal ectasia, altered enzymatic processes result in the synthesis of abnormal collagen. Collagen packing is determined by the activity of various extracellular matrix enzymes which bind amines and aldehydes of collagen fiber amino acids. In the late stage, morphological changes of Descemet’s membrane (i.e., rupture and detachment develop. Abnormal hexagonal-shaped keratocytes and their apoptosis are the signs of endothelial dystrophy. The lack of analogs in domestic ophthalmology encouraged the scientists of Ufa Eye Research Institute to develop a device for corneal collagen crosslinking. The parameters of ultraviolet (i.e., wavelength, exposure time, power to achieve the desired effect were identified. The specifics of some photosensitizers in the course of the procedure were studied. UFalink, a device for UV irradiation of cornea, and photosensitizer Dextralink were developed and adopted. Due to the high risk of endothelial damage, this treatment is contraindicated in severe keratoconus (CCT less than 400 microns. Major effects of corneal collagen crosslinking are the following: Young’s modulus (modulus of elasticity increase by 328.9 % (on average, temperature tolerance increase by 5

  16. Quantitative analysis of collagen and elastic fibers in the transversalis fascia in direct and indirect inguinal hernia Análise quantitativa do colágeno e de fibras elásticas na fascia transversal de pacientes com hernia inguinal direta e indireta

    Directory of Open Access Journals (Sweden)

    Aldo Junqueira Rodrigues Junior

    2002-01-01

    Full Text Available PURPOSE: Our previous studies demonstrated structural and quantitative age-related changes of the elastic fibers in transversalis fascia, which may play a role in inguinal hernia formation. To verify whether there were differences in the extracellular matrix between direct and indirect inguinal hernia, we studied the amount of collagen and elastic fibers in the transversalis fascia of 36 male patients with indirect inguinal hernia and 21 with direct inguinal hernia. MATERIAL AND METHODS: Transversalis fascia fragments were obtained during surgical intervention and underwent histological quantitative analysis of collagen by colorimetry and analysis of elastic fibers by histomorphometry. RESULTS: We demonstrated significantly lower amounts of collagen and higher amounts of elastic fibers in transversalis fascia from patients with direct inguinal hernia compared to indirect inguinal hernia patients. The transversalis fascia from direct inguinal hernia patients showed structural changes of the mature and elaunin elastic fibers, which are responsible for elasticity, and lower density of oxytalan elastic fibers, which are responsible for resistance. These changes promoted loss of resiliency of the transversalis fascia. CONCLUSION: These results improve our understanding of the participation of the extracellular matrix in the genesis of direct inguinal hernia, suggesting a relationship with genetic defects of the elastic fiber and collagen synthesis.OBJETIVO: Estudos prévios nossos demonstraram alterações estruturais e quantitativas de fibras elásticas na fascia transversal com o envelhecimento, tendo papel na gênese da hérnia inguinal. Com o objetivo de verificar diferenças na matriz extracellular da fascia transversal de pacientes com hernia inguinal direta e indireta, quantificamos o colágeno e as fibras elásticas na fascia transversal de 36 pacientes masculinos com hernia inguinal indireta e 21 pacientes masculinos com hernia inguinal

  17. Coexistence of native-like and non-native partially unfolded ferricytochrome c on the surface of cardiolipin-containing liposomes.

    Science.gov (United States)

    Pandiscia, Leah A; Schweitzer-Stenner, Reinhard

    2015-01-29

    Cytochrome c, in spite of adopting a rather rigid structure around its prosthetic heme group, is rather diverse with regard to its function and structural variability. On the surface of the inner membrane of mitochondria it serves as an electron transfer carrier. However, at conditions which have not yet been unambiguously identified, cytochrome c can adopt a variety of non-native conformations, some of which exhibit peroxidase activity. Cardiolipin-containing liposomes have served as ideal model system to investigate the various modes of interaction between cytochrome c and the inner mitochrondrial membrane. We probed the binding of horse heart ferricytochrome c to liposomes formed with 20% tetraoleoyl cardiolipin (TOCL) and 80% dioleoyl-sn-glycero-3-phosphocholine (DOPC) as a function of lipid/protein ratio by fluorescence and visible circular dichroism spectroscopy. The obtained binding isotherms suggest that they reflect reversible binding processes, which excludes the possibility of significant protein insertion into the membrane. A global analysis of our data revealed the existence of two binding sites on the protein which causes rather different degrees of protein unfolding. We found that these two modes of interaction between protein and liposome led to conformational changes. While site 1 is relatively unaffected by NaCl, site 2 shows a more native-like state or a higher population of the native state in the presence of NaCl. At the highest utilized concentration of NaCl, there is only a 40% inhibition of the binding to site 2. We interpret our finding for this binding site as reflecting an equilibrium between electrostatically bound proteins with a high degree of unfolding and less unfolded proteins which bind either via H-bonding between lysine side chains and PO2(-) or hydrophobic interactions. With regard to site 2 binding, our results are reminiscent of the two-state equilibrium between a compact C and an extended E-state proposed by Pletneva and co

  18. In situ observation of collagen thermal denaturation by second harmonic generation microscopy

    Science.gov (United States)

    Liao, C.-S.; Zhuo, Z.-Y.; Yu, J.-Y.; Chao, P.-H. G.; Chu, S.-W.

    2010-02-01

    Collagen denaturation is of fundamental importance for clinical treatment. Conventionally, the denaturation process is quantified by the shrinkage of collagen fibers, but the underlying molecular origin has not been fully understood. Since second harmonic generation (SHG) is related to the molecular packing of the triple helix in collagen fibers, this nonlinear signal provides an insight of molecular dynamics during thermal denaturation. With the aid of SHG microscopy, we found a new step in collagen thermal denaturation process, de-crimp. During the de-crimp step, the characteristic crimp pattern of collagen fascicles disappeared due to the breakage of interconnecting bonds between collagen fibrils, while SHG intensity remained unchanged, suggesting the intactness of the triple helical molecules. At higher temperature, shrinkage is observed with strongly reduced SHG intensity, indicating denaturation at the molecular level.

  19. Evaluation of oral mucosa collagen condition with cross-polarization optical coherence tomography.

    Science.gov (United States)

    Gladkova, Natalia; Kiseleva, Elena; Robakidze, Natalia; Balalaeva, Irina; Karabut, Maria; Gubarkova, Ekaterina; Feldchtein, Felix

    2013-04-01

    The goal of the research was analysis of the effect of collagen condition in formation of cross-polarized CP OCT images. We used of the CP OCT technique for studying collagen condition on an example of oral mucosa. Special histologic picrosirius red (PSR) staining of cheek mucosa specimens was used with subsequent assessing of the result of collagen staining in polarized light. High correlation (r = 0.692, p = 0.0001) between OCT signal standard deviation (SD) in cross-polarized images and brightness of PSR stained collagen fibers in cheek mucosa specimens was demonstrated in patients with inflammatory intestine and oral mucosa diseases. We have found that the OCT signal SD in cross-polarized images reflects two boundary conditions of collagen disorganization, namely, loss of fiber properties at active inflammation which attenuates the signal and fibrosis that occurs due to synthesis of a new remodeled collagen which amplifies the OCT signal.

  20. Thermal denaturation of UV-irradiated wet rat tail tendon collagen.

    Science.gov (United States)

    Sionkowska, Alina

    2005-04-01

    The thermal helix-coil transition of UV irradiated collagen in rat tail tendon has been investigated by differential scanning calorimetry. During UVB irradiation the tendons were immersed in water to keep the collagen fibers in a fully hydrated condition at all times. UV irradiation induced changes in collagen which caused both stabilization and destabilization of the triple helix in fibers. The helix-coil transition for non-irradiated collagen occurred near 64 degrees C, for irradiated 1 and 3 h at 66 and 67 degrees C, respectively. After irradiating for longer times (20-66 h) the helix-coil transition peak occurred at much lower temperatures. The peak was very broad and suggested that collagen was reduced by UV to different polypeptides of different molecular weight and different lower thermal stabilities. It was caused by the disruption of a network of hydrogen-bonded water molecules surrounding the collagen macromolecule.

  1. Heterogeneous force network in 3D cellularized collagen networks

    Science.gov (United States)

    Liang, Long; Jones, Christopher; Chen, Shaohua; Sun, Bo; Jiao, Yang

    2016-12-01

    Collagen networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the transmission of forces generated by contractile cells in 3D collagen-I networks. Specifically, the graph (bond-node) representations of collagen networks with collagen concentrations of 1, 2 and 4 mg ml-1 are derived from confocal microscopy data and used to model the network microstructure. Cell contraction is modeled by applying correlated displacements at specific nodes of the network, representing the focal adhesion sites. A nonlinear elastic model is employed to characterize the mechanical behavior of individual fiber bundles including strain hardening during stretching and buckling under compression. A force-based relaxation method is employed to obtain equilibrium network configurations under cell contraction. We find that for all collagen concentrations, the majority of the forces are carried by a small number of heterogeneous force chains emitted from the contracting cells, which is qualitatively consistent with our experimental observations. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to fiber reorientation induced by cell contraction. The decay of the forces along the force chains is significantly slower than the decay of radially averaged forces in the system, suggesting that the fibreous nature of biopolymer network structure can support long-range force transmission. The force chains emerge even at very small cell contractions, and the number of force chains increases with increasing cell contraction. At large cell contractions, the fibers close to the cell surface are in the nonlinear regime, and the nonlinear region is localized in a small neighborhood of the cell. In addition, the number of force chains increases with increasing collagen concentration, due to the larger number of focal adhesion sites

  2. Proximal collagenous gastroenteritides:

    DEFF Research Database (Denmark)

    Nielsen, Ole Haagen; Riis, Lene Buhl; Danese, Silvio

    2014-01-01

    a systematic review of collagenous gastritis, collagenous sprue, and a combination thereof. METHOD: The search yielded 117 studies which were suitable for inclusion in the systematic review. Excluding repeated cases, 89 case reports and 28 case series were reported, whereas no prospective studies...... of these disorders is presented. The prognosis of both collagenous gastritis and sprue seems not to be as dismal as considered previously. Data point to involvement of immune or autoimmune mechanisms potentially driven by luminal antigens initiating the fibroinflammatory condition. CONCLUSIONS: To reach...

  3. Scanning electron microscopic observation: three-dimensional architecture of the collagen in hepatic fibrosis rats

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-hong; ZHAO Jing; ZHANG Wei-guang; ZHANG Li-ying; MA Rui-qiong; WANG Li-qin; ZHANG Shu-yong; TIAN Long

    2007-01-01

    Background In the process of hepatic fibrosis, the accumulation of collagen fibers is strongly related to the hepatic function. The aim of this study was to investigate the three-dimensional architecture of the collagen network in the liver of rats with hepatic fibrosis.Methods Healthy adult male Wistar rats (n=32) were randomly divided into a control group (n=16) and a hepatic fibrosis group (n=16). In the control group, the rats were treated with peanut oil while the rats in hepatic fibrosis group were treated for 10 weeks with 60% CCl4 diluted in peanut oil. The quantity of collagen fibers was detected by Western blotting; distribution of the collagen was detected by sirius red staining and polarized microscope; the three-dimensional architecture of collagen in the liver was observed under the scanning electron microscope after fixed tissues were treated with cell-maceration using NaOH. Statistical analysis was performed using the u test.Results The quantity of collagen fibers increased significantly in the hepatic fibrosis group. With the aggravation of hepatic fibrosis, collagen fibers gradually accumulated. They interlaced the reticulation compartment and formed a round or ellipse liver tissue conglomeration like a grape framework that was disparate and wrapped up the normal liver Iobule.The deposition of collagen fibers was obvious in adjacent hepatic parenchyma, especially around the portal tracts.Conclusion Our experiment showed the collagen proliferation and displays clearly the three-dimensional architecture of collagen fibers in rat liver with hepatic fibrosis by scanning electron microscope. It can provide a morphological foundation for the mechanisms of changed haemodynamics and portal hypertension in hepatic fibrosis.

  4. Evaluation of nanostructural, mechanical, and biological properties of collagen-nanotube composites.

    Science.gov (United States)

    Tan, Wei; Twomey, John; Guo, Dongjie; Madhavan, Krishna; Li, Min

    2010-06-01

    Collagen I is an essential structural and mechanical building block of various tissues, and it is often used as tissue-engineering scaffolds. However, collagen-based constructs reconstituted in vitro often lacks robust fiber structure, mechanical stability, and molecule binding capability. To enhance these performances, the present study developed 3-D collagen-nanotube composite constructs with two types of functionalized carbon nanotubes, carboxylated nanotubes and covalently functionalized nanotubes (CFNTs). The influences of nanotube functionalization and loading concentration on the collagen fiber structure, mechanical property, biocompatibility, and molecule binding were examined. Results revealed that surface modification and loading concentration of nanotubes determined the interactions between nanotubes and collagen fibrils, thus altering the structure and property of nanotube-collagen composites. Scanning electron microscopy and confocal microscopy revealed that the incorporation of CFNT in collagen-based constructs was an effective means of restructuring collagen fibrils because CFNT strongly bound to collagen molecules inducing the formation of larger fibril bundles. However, increased nanotube loading concentration caused the formation of denser fibril network and larger aggregates. Static stress-strain tests under compression showed that the addition of nanotube into collagen-based constructs did not significantly increase static compressive moduli. Creep/recovery testing under compression revealed that CFNT-collagen constructs showed improved mechanical stability under continuous loading. Testing with endothelial cells showed that biocompatibility was highly dependent on nanotube loading concentration. At a low loading level, CFNT-collagen showed higher endothelial coverage than the other tested constructs or materials. Additionally, CFNT-collagen showed capability of binding to other biomolecules to enhance the construct functionality. In conclusion

  5. Subcellular localization of transglutaminase. Effect of collagen.

    Science.gov (United States)

    Juprelle-Soret, M; Wattiaux-De Coninck, S; Wattiaux, R

    1988-01-01

    1. The subcellular distribution of transglutaminase was investigated by using the analytical approach of differential and isopycnic centrifugation as applied to three organs of the rat: liver, kidney and lung. After differential centrifugation by the method of de Duve, Pressman, Gianetto, Wattiaux & Appelmans [(1955) Biochem. J. 63, 604-617], transglutaminase is mostly recovered in the unsedimentable fraction S and the nuclear fraction N. After isopycnic centrifugation of the N fraction in a sucrose density gradient, a high proportion of the enzyme remains at the top of the gradient; a second but minor peak of activity is present in high-density regions, where a small proportion of 5'-nucleotidase, a plasma-membrane marker, is present together with a large proportion of collagen recovered in that fraction. 2. Fractions where a peak of transglutaminase was apparent in the sucrose gradient were examined by electron microscopy. The main components are large membrane sheets with extracellular matrix and free collagen fibers. 3. As these results seem to indicate that some correlation exists between particulate transglutaminase distribution and those of collagen and plasma membranes, the possible binding of transglutaminase by collagen (type I) and by purified rat liver plasma membrane was investigated. 4. The binding studies indicated that collagen is able to bind transglutaminase and to make complexes with plasma-membrane fragments whose density is higher than that of plasma-membrane fragments alone. Transglutaminase cannot be removed from such complexes by 1% Triton X-100, but can be to a relatively large extent by 0.5 M-KCl and by 50% (w/v) glycerol. 5. Such results suggest that the apparent association of transglutaminase with plasma membrane originates from binding in vitro of the cytosolic enzyme to plasma membrane bound to collagen, which takes place during homogenization of the tissue, when the soluble enzyme and extracellular components are brought together

  6. Fabrication of Mineralized Collagen from Bovine Waste Materials by Hydrothermal Method as Promised Biomaterials

    DEFF Research Database (Denmark)

    Sheikh, Faheem A.; Kanjwal, Muzafar Ahmed; Macossay, Javier

    2011-01-01

    In the present study, we aimed to produce mineralized-collagen by hydrothermal process. A simple method not depending on additional foreign chemicals has been employed to isolate the mineralized-collagen fibers from bovine waste. The process of extraction involves the use of hydrothermal method...

  7. Transformation of amorphous calcium carbonate to rod-like single crystal calcite via "copying" collagen template.

    Science.gov (United States)

    Xue, Zhonghui; Hu, Binbin; Dai, Shuxi; Du, Zuliang

    2015-10-01

    Collagen Langmuir films were prepared by spreading the solution of collagen over deionized water, CaCl2 solution and Ca(HCO3)2 solution. Resultant collagen Langmuir monolayers were then compressed to a lateral pressure of 10 mN/m and held there for different duration, allowing the crystallization of CaCO3. The effect of crystallization time on the phase composition and microstructure of CaCO3 was investigated. It was found that amorphous calcium carbonate (ACC) was obtained at a crystallization time of 6 h. The amorphous CaCO3 was transformed to rod-like single crystal calcite crystals at an extended crystallization time of 12 h and 24 h, via "copying" the symmetry and dimensionalities of collagen fibers. Resultant calcite crystallites were well oriented along the longitudinal axis of collagen fibers. The ordered surface structure of collagen fibers and electrostatic interactions played key roles in tuning the oriented nucleation and growth of the calcite crystallites. The mineralized collagen possessing both desired mechanical properties of collagen fiber and good biocompatibility of calcium carbonate may be assembled into an ideal biomaterial for bone implants.

  8. Collagenous gastritis: Review

    Institute of Scientific and Technical Information of China (English)

    Kenya Kamimura; Masaaki Kobayashi; Yuichi Sato; Yutaka Aoyagi; Shuji Terai

    2015-01-01

    Collagenous gastritis is a rare disease characterizedby the subepithelial deposition of collagen bandsthicker than 10 μm and the infiltration of inflammatorymononuclear cells in the lamina propria. Collagenouscolitis and collagenous sprue have similar histologicalcharacteristics to collagenous gastritis and are thoughtto be part of the same disease entity. However, whilecollagenous colitis has become more common inthe field of gastroenterology, presenting with clinicalsymptoms of chronic diarrhea in older patients,collagenous gastritis is rare. Since the disease was firstreported in 1989, only 60 cases have been documentedin the English literature. No safe and effective treatmentshave been identified from randomized, controlled trials.Therefore, better understanding of the disease and thereporting of more cases will help to establish diagnosticcriteria and to develop therapeutic strategies. Therefore,here we review the clinical characteristics, endoscopicand histological findings, treatment, and clinical outcomesfrom case reports and case series published to date,and provide a summary of the latest information on thedisease. This information will contribute to improvedknowledge of collagenous gastritis so physicians canrecognize and correctly diagnose the disease, and willhelp to develop a standard therapeutic strategy forfuture clinical trials.

  9. Type I collagen is thermally unstable at body temperature.

    Science.gov (United States)

    Leikina, E; Mertts, M V; Kuznetsova, N; Leikin, S

    2002-02-05

    Measured by ultra-slow scanning calorimetry and isothermal circular dichroism, human lung collagen monomers denature at 37 degrees C within a couple of days. Their unfolding rate decreases exponentially at lower temperature, but complete unfolding is observed even below 36 degrees C. Refolding of full-length, native collagen triple helices does occur, but only below 30 degrees C. Thus, contrary to the widely held belief, the energetically preferred conformation of the main protein of bone and skin in physiological solution is a random coil rather than a triple helix. These observations suggest that once secreted from cells collagen helices would begin to unfold. We argue that initial microunfolding of their least stable domains would trigger self-assembly of fibers where the helices are protected from complete unfolding. Our data support an earlier hypothesis that in fibers collagen helices may melt and refold locally when needed, giving fibers their strength and elasticity. Apparently, Nature adjusts collagen hydroxyproline content to ensure that the melting temperature of triple helical monomers is several degrees below rather than above body temperature.

  10. Development of poly (lactic-co-glycolic acid)-collagen scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Wen, F. [Department of Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore); Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore (Singapore); Institute of Bioengineering and Nanotechnology (IBN), ASTAR (Singapore); Graduate Program in Bioengineering (GPBE), NUS Graduate School of Integrative Sciences and Engineering (NGS), National University of Singapore (Singapore); Chang, S. [Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore (Singapore); Department of General Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan (China); Toh, Y.C. [Institute of Bioengineering and Nanotechnology (IBN), ASTAR (Singapore); Graduate Program in Bioengineering (GPBE), NUS Graduate School of Integrative Sciences and Engineering (NGS), National University of Singapore (Singapore); Teoh, S.H. [Department of Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore); Graduate Program in Bioengineering (GPBE), NUS Graduate School of Integrative Sciences and Engineering (NGS), National University of Singapore (Singapore); NUS Tissue Engineering Programme (NUSTEP) (Singapore); Yu, H. [Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore (Singapore) and Institute of Bioengineering and Nanotechnology (IBN), ASTAR, Singapore and Graduate Program in Bioengineering (GPBE), NUS Graduate School of Integrative Sciences and Engineering - NGS, National University of Singapore (Singapore)]. E-mail: phsyuh@nus.edu.sg

    2007-03-15

    Collagen as an important extra-cellular matrix (ECM) in many tissues is weakly antigenic and the structure of collagen sponges is highly porous with interconnected pores effective for cell infiltration and mass transfer of oxygen and nutrients. Its application as a scaffold is limited by poor mechanical strength and rapid biodegradation. In this paper, we attempt to graft hydrolyzed PLGA fiber surfaces with collagen by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) in combination with N-hydroxysuccinimide (NHS), and then embed these collagen-grafted PLGA fibers in collagen sponge to form a hybrid PLGA-collagen scaffold. For further stability, we cross-linked the collagen in the scaffold and used it in rat liver cell cultivation. The scaffold was characterized by mechanical micro-tester, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results showed that (1) the scaffolds exhibited isotropic and interconnected porous structure; (2) the compression modulus of this scaffold was enhanced 50 fold compared to the collagen scaffolds. The cell attachment and cytotoxicity of this scaffold were studied. Cell attachment was improved remarkably and the cytotoxicity of the hybrid PLGA-collagen scaffold was lower than that of the un-grafted PLGA-collagen scaffolds using alamarBlue{sup TM} assay normalized to the DNA content in each scaffold. This new hybrid scaffold has potential applications for tissue engineering.

  11. Breast epithelial tissue morphology is affected in 3D cultures by species-specific collagen-based extracellular matrix.

    Science.gov (United States)

    Dhimolea, Eugen; Soto, Ana M; Sonnenschein, Carlos

    2012-11-01

    Collagen-based gels have been widely used to determine the factors that regulate branching morphogenesis in the mammary gland. The patterns of biomechanical gradients and collagen reorganization influence the shape and orientation of epithelial structures in three-dimensional (3D) conditions. We explored in greater detail whether collagen type I fibers with distinct biomechanical and fiber-assembling properties, isolated from either bovine or rat tail tendon, differentially affected the epithelial phenotype in a tissue culture model of the human breast. Rat tail collagen fibers were densely packed into significantly longer and thicker bundles compared to those of the bovine type (average fascicle length 7.35 and 2.29 μm, respectively; p = 0.0001), indicating increased fiber alignment and biomechanical enablement in the former. MCF10A epithelial cells formed elaborated branched tubular structures in bovine but only nonbranched ducts and acini in rat tail collagen matrices. Ductal branching in bovine collagen was associated with interactions between neighboring structures mediated through packed collagen fibers; these fiber-mediated interactions were absent in rat tail collagen gels. Normal breast fibroblasts increased the final size and number of ducts only in rat tail collagen gels while not affecting branching. Our results suggest that the species of origin of collagen used in organotypic cultures may influence epithelial differentiation into alveolar or ductal structures and the patterns of epithelial branching. These observations underscore the importance of considering the species of origin and fiber alignment properties of collagen when engineering branching organs in 3D matrices and interpreting their role in the tissue phenotype.

  12. Fast increase of proteinase inhibitors in necrotic collagenous tissue.

    Science.gov (United States)

    Oehmichen, M

    1989-01-01

    Using the PAP immunohistochemical technique, accumulation of two proteinase inhibitors, alpha-1-antichymotrypsin and alpha-2-macroglobulin, can be detected at the edges of collagenous fibers in the corium after slash wounds of the skin. This accumulation was observed within a survival time of 10-30 min. It, however, is not detectable in postmortally inflicted trauma.

  13. [Corneal collagen cross-linking for keratoconus].

    Science.gov (United States)

    Zotov, V V; Pashtaev, N P; Pozdeeva, N A

    2015-01-01

    Over the last decade, corneal collagen cross-linking (CXL) has become a conventional treatment method for progressive keratoconus. Laboratory studies have shown that CXL increases the diameter of collagen fibers and also the number of intra- and interfibrillar cross-links, thus, increasing biomechanical strength of the irradiated cornea. As confirmed by a series of clinical and randomized controlled trials, CXL is able to slow down and, perhaps, to stop the progression of keratoconus. In most post-CXL patients visual acuity improves, while keratometric readings, spherical equivalent, and higher order aberrations reduce. Although published results prove CXL effective in the treatment of progressive keratoconus, its late consequences are yet unknown. This article reviews the stages of CXL development and results of published experimental and clinical studies. Prospects for CXL modifications that do not require epithelial debridement are discussed.

  14. Design and synthesis of collagen mimetic peptide derivatives for studying triple helix assembly and collagen mimetic peptide-collagen binding interaction

    Science.gov (United States)

    Mo, Xiao

    2008-10-01

    Collagen is the principal tensile clement of the extra-cellular matrix in mammals and is the basic scaffold for cells and tissues. Collagen molecules are comprised of homo-trimeric helices (e.g. collagen type II and type III), ABB type hetero-trimeric helices (e.g. collagen type I, type IV, and type V), or ABC type hetero-trimeric helices (e.g. type V). Mimicry of collagen structures can help elucidate collagen triple helical conformation and provide insights into making novel collagen-like biomaterials. Our group previously reported a new physical collagen modification method, which was based on non-covalent interaction between collagen mimetic peptide (CMP: -(Pro-Hyp-Gly) x-) and natural collagen. We hypothesized that CMP binds to collagen through a process involving both strand invasion and triple helix assembly. The aim of this dissertation is to study structural formation and stability of collagen triple helix, and to investigate CMP-collagen binding interactions using two types of CMP derivatives: covalently templated CMP trimer and CMP-nanoparticle conjugates. We demonstrated that covalently templated ABB type CMP hetero-trimers could be prepared by a versatile synthetic strategy involving both solid phase and solution peptide coupling. Our thermal melting studies showed that the templated CMP hetero-trimers formed collagen-like triple helices and their folding kinetics correlated with the amino acid compositions of the individual CMP strands. We also studied the thermal melting behavior and folding kinetics of a templated hetero-trimer complex comprised of CMP and a peptide derived from collagen. This synthetic strategy can be readily extended to synthesize other ABB type hetero-trimers to investigate their local melting behavior and biological activity. We also prepared colloidally stable CMP functionalized gold nanoparticles (Au-CMPs) as a TEM marker for investigating the CMP-collagen interaction. Au-CMP showed preferential binding to collagen fiber's gap

  15. [Expression of type VI collagen in arthrofibrosis. An immunohistochemical study].

    Science.gov (United States)

    Zeichen, J; van Griensven, M; Lobenhoffer, P; Bosch, U

    2000-08-01

    Arthrofibrosis is a disabling complication after trauma and surgery due to massive connective tissue proliferation. The etiology and pathogenesis have never been fully understood. A strong immune response may lead to activation and proliferation of fibroblasts with excessive and disordered deposition of matrix proteins. In similar pathological conditions, like lung fibrosis or superficial fibromatoses with fibrotic transformation an increased expression of collagen type VI has been reported. We investigated fibrotic tissue samples taken from 18 patients (average age: 32.7 years), who underwent arthrolysis of the knee joint because of symptomatic arthrofibrosis following ligament injury. The mean interval between trauma and arthrolysis was 13.8 months (range 4-50 months). Tissue samples were taken from the infrapatellar fat pad and intercondylar connective tissue. All samples were stained with HE. The expression of type III and VI collagen was studied immunohistochemically using an immunoperoxidase method for light microscopic visualization. Histologic analysis from patients with arthrofibrosis showed a synovial hyperplasia with cell infiltration and vascular proliferation compared to synovial tissue samples from knee joints without any detectable pathology. Subsynovial an increased deposition of matrix proteins was visible. Type VI collagen was widely distributed as a network subsynovial and around capillary walls. Type III collagen showed a diffuse distribution. Arthrofibrotic tissue is, similar to pathological conditions with fibrotic transformation characterized by an increased expression of collagen type VI. Collagen type VI may play an important role in matrix homeostasis. It serves as an anchoring element between collagen fibers and as a cell binding structure.

  16. Effects of Collagen and Collagen Hydrolysate from Jellyfish Umbrella on Histological and Immunity Changes of Mice Photoaging

    Directory of Open Access Journals (Sweden)

    Yongliang Zhuang

    2013-01-01

    Full Text Available Jellyfish collagen (JC was extracted from jellyfish umbrella and hydrolyzed to prepare jellyfish collagen hydrolysate (JCH. The effects of JC and JCH on UV-induced skin damage of mice were evaluated by the skin moisture, microscopic analyses of skin and immunity indexes. The skin moisture analyses showed that moisture retention ability of UV-induced mice skin was increased by JC and JCH. Further histological analysis showed that JC and JCH could repair the endogenous collagen and elastin protein fibers, and could maintain the natural ratio of type I to type III collagen. The immunity indexes showed that JC and JCH play a role in enhancing immunity of photoaging mice in vivo. JCH showed much higher protective ability than JC. These results suggest that JCH as a potential novel antiphotoaging agent from natural resources.

  17. Collagen metabolism in obesity

    DEFF Research Database (Denmark)

    Rasmussen, M H; Jensen, L T; Andersen, T

    1995-01-01

    OBJECTIVE: To investigate the impact of obesity, fat distribution and weight loss on collagen turnover using serum concentrations of the carboxyterminal propeptide of type I procollagen (S-PICP) and the aminoterminal propeptide of type III pro-collagen (S-PIIINP) as markers for collagen turnover...... (r = 0.37; P = 0.004), height (r = 0.27; P = 0.04), waist circumference (r = 0.35; P = 0.007), as well as with WHR (r = 0.33; P = 0.01) and was inversely correlated to age (r = -0.40; P = 0.002). Compared with randomly selected controls from a large pool of healthy volunteers, the obese patients had...... restriction (P obesity and associated with body fat distribution, suggesting...

  18. Collagen Homeostasis and Metabolism

    DEFF Research Database (Denmark)

    Magnusson, S Peter; Heinemeier, Katja M; Kjaer, Michael

    2016-01-01

    The musculoskeletal system and its collagen rich tissue is important for ensuring architecture of skeletal muscle, energy storage in tendon and ligaments, joint surface protection, and for ensuring the transfer of muscular forces into resulting limb movement. Structure of tendon is stable...... inactivity or immobilization of the human body will conversely result in a dramatic loss in tendon stiffness and collagen synthesis. This illustrates the importance of regular mechanical load in order to preserve the stabilizing role of the connective tissue for the overall function of the musculoskeletal...

  19. Decrimping: The first stage of collagen thermal denaturation unraveled by in situ second-harmonic-generation imaging

    Science.gov (United States)

    Liao, Chien-Sheng; Zhuo, Zong-Yan; Yu, Jiun-Yann; Tzeng, Yu-Yi; Chu, Shi-Wei; Yu, Shih-Fan; Chao, Pen-Hsiu Grace

    2011-04-01

    With polarized and time-lapsed second-harmonic-generation (SHG) imaging, three distinct thermodynamic stages are revealed during heating of collagenous tissue. In the first "decrimping" stage, SHG intensity remains unchanged while the characteristic crimp pattern of collagen fiber disappears. The intactness of underlying fibrils is confirmed by unaffected second-order susceptibility, suggesting decrimping is related to the breakage of cross-linking between collagen fibrils. In the latter stages, significant SHG decrease is observed, providing quantification to collagen thermal denaturation. This study manifests the benefits of adopting SHG for understanding the thermal response of collagen, and will be useful toward better thermal therapy design.

  20. Imaging of Scleral Collagen Deformation Using Combined Confocal Raman Microspectroscopy and Polarized Light Microscopy Techniques.

    Science.gov (United States)

    Chakraborty, Nilay; Wang, Mian; Solocinski, Jason; Kim, Wonsuk; Argento, Alan

    2016-01-01

    This work presents an optospectroscopic characterization technique for soft tissue microstructure using site-matched confocal Raman microspectroscopy and polarized light microscopy. Using the technique, the microstructure of soft tissue samples is directly observed by polarized light microscopy during loading while spatially correlated spectroscopic information is extracted from the same plane, verifying the orientation and arrangement of the collagen fibers. Results show the response and orientation of the collagen fiber arrangement in its native state as well as during tensile and compressive loadings in a porcine sclera model. An example is also given showing how the data can be used with a finite element program to estimate the strain in individual collagen fibers. The measurements demonstrate features that indicate microstructural reorganization and damage of the sclera's collagen fiber arrangement under loading. The site-matched confocal Raman microspectroscopic characterization of the tissue provides a qualitative measure to relate the change in fibrillar arrangement with possible chemical damage to the collagen microstructure. Tests and analyses presented here can potentially be used to determine the stress-strain behavior, and fiber reorganization of the collagen microstructure in soft tissue during viscoelastic response.

  1. [The genetics of collagen diseases].

    Science.gov (United States)

    Kaplan, J; Maroteaux, P; Frezal, J

    1986-01-01

    Heritable disorders of collagen include Ehler-Danlos syndromes (11 types are actually known), Larsen syndrome and osteogenesis imperfecta. Their clinical, genetic and biochemical features are reviewed. Marfan syndrome is closely related to heritable disorders of collagen.

  2. Collagen turnover after tibial fractures

    DEFF Research Database (Denmark)

    Joerring, S; Krogsgaard, M; Wilbek, H

    1994-01-01

    Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...... after 2 weeks in the diaphyseal fractures and after 6 weeks in the condylar fractures. The degradation of type I collagen increased after 4 days and reached a maximum at 2 weeks in both groups. The interindividual variation was wide. On a group basis, the turnover of types I and III collagen had...

  3. Characterization of the correlation between collagen fibril thickness and forward and backward second harmonic signal

    Science.gov (United States)

    Hsueh, Chiu-Mei; Hovhannisyan, Vladimir A.; Dong, Chen-Yuan

    2011-07-01

    Optical-based microscopy plays an important role in various scientific fields such as physics, chemistry and biology. Second harmonic generation (SHG) microscopy has become one of the indispensable tools for biomedical imaging for the last decade because the signal generated from SHG is sensitive to the objective structure and this amazing non-invasive method can also directly observe the objective without using extra fluorescent labels, especially for collagen molecules. As the most abundant protein in animals, collagen is responsible for a number of important structural and functional roles in vertebrates. For certain diseases, it has been shown that collagen fiber diameter has a significant variation and thus as a vital symptom for diagnosis. Moreover, collagen diameter is also a key parameter for fibrogenesis studying. Therefore, the determination of collagen fiber diameter is important for studying biophysical processes and identifying bioengineering applications. In this study, we investigated various collagen fibril thicknesses and the corresponding forward (FSHG) and backward (BSHG) second harmonic signal intensity variation. Our result exhibits that SHG intensity can quantify describe the relative collagen fibril thickness alteration, which also indicates the coherent effect difference between FSHG and BSHG. This approach demonstrates the capability of SHG imaging in providing collagen mechanical information and that may be applied in the evaluation of advancing collagen issues in vivo.

  4. Regulation of collagen fibrillogenesis by cell-surface expression of kinase dead DDR2.

    Science.gov (United States)

    Blissett, Angela R; Garbellini, Derek; Calomeni, Edward P; Mihai, Cosmin; Elton, Terry S; Agarwal, Gunjan

    2009-01-23

    The assembly of collagen fibers, the major component of the extracellular matrix (ECM), governs a variety of physiological processes. Collagen fibrillogenesis is a tightly controlled process in which several factors, including collagen binding proteins, have a crucial role. Discoidin domain receptors (DDR1 and DDR2) are receptor tyrosine kinases that bind to and are phosphorylated upon collagen binding. The phosphorylation of DDRs is known to activate matrix metalloproteases, which in turn cleave the ECM. In our earlier studies, we established a novel mechanism of collagen regulation by DDRs; that is, the extracellular domain (ECD) of DDR2, when used as a purified, soluble protein, inhibits collagen fibrillogenesis in-vitro. To extend this novel observation, the current study investigates how the DDR2-ECD, when expressed as a membrane-anchored, cell-surface protein, affects collagen fibrillogenesis by cells. We generated a mouse osteoblast cell line that stably expresses a kinase-deficient form of DDR2, termed DDR2/-KD, on its cell surface. Transmission electron microscopy, fluorescence microscopy, and hydroxyproline assays demonstrated that the expression of DDR2/-KD reduced the rate and abundance of collagen deposition and induced significant morphological changes in the resulting fibers. Taken together, our observations extend the functional roles that DDR2 and possibly other membrane-anchored, collagen-binding proteins can play in the regulation of cell adhesion, migration, proliferation and in the remodeling of the extracellular matrix.

  5. Inhibition of collagen fibrillogenesis by cells expressing soluble extracellular domains of DDR1 and DDR2.

    Science.gov (United States)

    Flynn, Lisa A; Blissett, Angela R; Calomeni, Edward P; Agarwal, Gunjan

    2010-01-22

    Collagen fiber assembly affects many physiological processes and is tightly controlled by collagen-binding proteins. However, to what extent membrane-bound versus cell-secreted collagen-binding proteins affect collagen fibrillogenesis is not well understood. In our previous studies, we had demonstrated that the membrane-anchored extracellular domain (ECD) of the collagen receptor discoidin domain receptor 2 (DDR2) inhibits fibrillogenesis of collagen endogenously secreted by the cells. These results led to a novel functional role of the DDR2 ECD. However, since soluble forms of DDR1 and DDR2 containing its ECD are known to naturally exist in the extracellular matrix, in this work we investigated if these soluble DDR ECDs may have a functional role in modulating collagen fibrillogenesis. For this purpose, we created mouse osteoblast cell lines stably secreting DDR1 or DDR2 ECD as soluble proteins. Transmission electron microscopy, fluorescence microscopy, and hydroxyproline assays were used to demonstrate that DDR ECD expression reduced the rate and quantity of collagen deposition and induced significant changes in fiber morphology and matrix mineralization. Collectively, our studies advance our understanding of DDR receptors as powerful regulators of collagen deposition in the ECM and elucidate their multifaceted role in ECM remodeling.

  6. Collagen reorganization at the tumor-stromal interface facilitates local invasion

    Directory of Open Access Journals (Sweden)

    Inman David R

    2006-12-01

    Full Text Available Abstract Background Stromal-epithelial interactions are of particular significance in breast tissue as misregulation of these interactions can promote tumorigenesis and invasion. Moreover, collagen-dense breast tissue increases the risk of breast carcinoma, although the relationship between collagen density and tumorigenesis is not well understood. As little is known about epithelial-stromal interactions in vivo, it is necessary to visualize the stroma surrounding normal epithelium and mammary tumors in intact tissues to better understand how matrix organization, density, and composition affect tumor formation and progression. Methods Epithelial-stromal interactions in normal mammary glands, mammary tumors, and tumor explants in three-dimensional culture were studied with histology, electron microscopy, and nonlinear optical imaging methodologies. Imaging of the tumor-stromal interface in live tumor tissue ex vivo was performed with multiphoton laser-scanning microscopy (MPLSM to generate multiphoton excitation (MPE of endogenous fluorophores and second harmonic generation (SHG to image stromal collagen. Results We used both laser-scanning multiphoton and second harmonic generation microscopy to determine the organization of specific collagen structures around ducts and tumors in intact, unfixed and unsectioned mammary glands. Local alterations in collagen density were clearly seen, allowing us to obtain three-dimensional information regarding the organization of the mammary stroma, such as radiating collagen fibers that could not have been obtained using classical histological techniques. Moreover, we observed and defined three tumor-associated collagen signatures (TACS that provide novel markers to locate and characterize tumors. In particular, local cell invasion was found predominantly to be oriented along certain aligned collagen fibers, suggesting that radial alignment of collagen fibers relative to tumors facilitates invasion. Consistent

  7. Collagen hydrolysate based collagen/hydroxyapatite composite materials

    Science.gov (United States)

    Ficai, Anton; Albu, Madalina Georgiana; Birsan, Mihaela; Sonmez, Maria; Ficai, Denisa; Trandafir, Viorica; Andronescu, Ecaterina

    2013-04-01

    The aim of this study was to study the influence of collagen hydrolysate (HAS) on the formation of ternary collagen-hydrolysate/hydroxyapatite composite materials (COLL-HAS/HA). During the precipitation process of HA, a large amount of brushite is resulted at pH = 7 but, practically pure HA is obtained at pH ⩾ 8. The FTIR data reveal the duplication of the most important collagen absorption bands due to the presence of the collagen hydrolysate. The presence of collagen hydrolysate is beneficial for the management of bone and joint disorders such as osteoarthritis and osteoporosis.

  8. Non-invasive molecular imaging of fibrosis using a collagen-targeted peptidomimetic of the platelet collagen receptor glycoprotein VI.

    Directory of Open Access Journals (Sweden)

    Julien Muzard

    Full Text Available BACKGROUND: Fibrosis, which is characterized by the pathological accumulation of collagen, is recognized as an important feature of many chronic diseases, and as such, constitutes an enormous health burden. We need non-invasive specific methods for the early diagnosis and follow-up of fibrosis in various disorders. Collagen targeting molecules are therefore of interest for potential in vivo imaging of fibrosis. In this study, we developed a collagen-specific probe using a new approach that takes advantage of the inherent specificity of Glycoprotein VI (GPVI, the main platelet receptor for collagens I and III. METHODOLOGY/PRINCIPAL FINDINGS: An anti-GPVI antibody that neutralizes collagen-binding was used to screen a bacterial random peptide library. A cyclic motif was identified, and the corresponding peptide (designated collagelin was synthesized. Solid-phase binding assays and histochemical analysis showed that collagelin specifically bound to collagen (Kd 10(-7 M in vitro, and labelled collagen fibers ex vivo on sections of rat aorta and rat tail. Collagelin is therefore a new specific probe for collagen. The suitability of collagelin as an in vivo probe was tested in a rat model of healed myocardial infarctions (MI. Injecting Tc-99m-labelled collagelin and scintigraphic imaging showed that uptake of the probe occurred in the cardiac area of rats with MI, but not in controls. Post mortem autoradiography and histological analysis of heart sections showed that the labeled areas coincided with fibrosis. Scintigraphic molecular imaging with collagelin provides high resolution, and good contrast between the fibrotic scars and healthy tissues. The capacity of collagelin to image fibrosis in vivo was confirmed in a mouse model of lung fibrosis. CONCLUSION/SIGNIFICANCE: Collagelin is a new collagen-targeting agent which may be useful for non-invasive detection of fibrosis in a broad spectrum of diseases.

  9. Col-F, a fluorescent probe for ex vivo confocal imaging of collagen and elastin in animal tissues.

    Science.gov (United States)

    Biela, Ewa; Galas, Jerzy; Lee, Brian; Johnson, Gary L; Darzynkiewicz, Zbigniew; Dobrucki, Jurek W

    2013-06-01

    A new low-molecular-weight fluorescent probe, Col-F, that exhibits affinity to collagen and elastin, was used successfully in imaging of extracellular matrix in freshly excised animal tissues. Col-F readily penetrates between live cells into tissues and binds to fibers of collagen and elastin by a noncovalent mechanism. Fibers of collagen and elastin have been stained in a variety of tissues, including tendon, skeletal muscle, connective tissue, and arteries. Cells migrating in a Col-F-stained collagenous biomaterial were also imaged. No phototoxic effects were detected when live keratocytes were imaged in the in vitro culture in the presence of Col-F. In conclusion, Col-F provides a simple and convenient tool for fluorescence three-dimensional imaging of intricate collagenous and elastic structures in live and fixed animal tissues, as well as in collagen-containing biomaterials.

  10. Functional study on two artificial liver bioreactors with collagen gel

    Directory of Open Access Journals (Sweden)

    XU Bing

    2014-10-01

    Full Text Available ObjectiveTo improve the hollow fiber bioreactor of artificial liver. MethodsRat hepatocytes mixed with collagen solution were injected into the external cavity of a hollow fiber reactor to construct a bioreactor of hepatocytes suspended in collagen gel (group Ⅰ. Other rat hepatocytes suspended in solution were injected into the external cavity of a hollow fiber reactor with a layer of collagen on the wall of the external cavity to construct a bioreactor of collagen layer and hepatocytes (group Ⅱ. For each group, the culture solution circulated through the internal cavity of the hollow fiber bioreactor; the bioreactor was put in a culture box for 9 d, and the culture solution in the internal cavity was exchanged for new one every 24 h; the concentrations of albumin (Alb, urea, and lactate dehydrogenase (LDH in the culture solution samples were measured to examine the hepatocyte function of the bioreactor. Statistical analysis was performed using SPSS 130. Continuous data were expressed as mean±SD, and comparison between groups was made by paired t test. ResultsFor groups Ⅰ and Ⅱ, Alb levels reached peak values on day 3 of culture (1.41±0.08 g/L and 0.65±0.05 g/L; from day 3 to 9, group I had a significantly higher Alb level than group Ⅱ (t>7.572, P<0.01. For groups Ⅰ and Ⅱ, urea levels reached peak values on days 3 and 5 of culture (1.73±0.14 mmol/L and 1.56±0.18 mmol/L; from days 5 to 9, group I had a significantly higher urea level than group Ⅱ (t>8.418, P<0.01. For groups Ⅰ and Ⅱ, LDH levels reached peak values on day 9 of culture (32.03±9.13 U/L and 70.17±25.28 U/L; from days 1 to 9, group I had a significantly lower LDH level than group Ⅱ(t>5.633, P<0.01. Therefore, the bioreactor of hepatocytes suspended in collagen gel (group Ⅰ showed a better hepatocyte function and less hepatic enzyme leakage compared with the bioreactor of collagen layer and hepatocytes (group Ⅱ. Conclusion

  11. Mechanical properties of a collagen fibril under simulated degradation.

    Science.gov (United States)

    Malaspina, David C; Szleifer, Igal; Dhaher, Yasin

    2017-11-01

    Collagen fibrils are a very important component in most of the connective tissue in humans. An important process associated with several physiological and pathological states is the degradation of collagen. Collagen degradation is usually mediated by enzymatic and non-enzymatic processes. In this work we use molecular dynamics simulations to study the influence of simulated degradation on the mechanical properties of the collagen fibril. We applied tensile stress to the collagen fiber at different stages of degradation. We compared the difference in the fibril mechanical priorities due the removal of enzymatic crosslink, surface degradation and volumetric degradation. As anticipated, our results indicated that, regardless of the degradation scenario, fibril mechanical properties is reduced. The type of degradation mechanism (crosslink, surface or volumetric) expressed differential effect on the change in the fibril stiffness. Our simulation results showed dramatic change in the fibril stiffness with a small amount of degradation. This suggests that the hierarchical structure of the fibril is a key component for the toughness and is very sensitive to changes in the organization of the fibril. The overall results are intended to provide a theoretical framework for the understanding the mechanical behavior of collagen fibrils under degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Biaxial stress relaxation of semilunar heart valve leaflets during simulated collagen catabolism: Effects of collagenase concentration and equibiaxial strain state.

    Science.gov (United States)

    Huang, Siyao; Huang, Hsiao-Ying Shadow

    2015-10-01

    Heart valve leaflet collagen turnover and remodeling are innate to physiological homeostasis; valvular interstitial cells routinely catabolize damaged collagen and affect repair. Moreover, evidence indicates that leaflets can adapt to altered physiological (e.g. pregnancy) and pathological (e.g. hypertension) mechanical load states, tuning collagen structure and composition to changes in pressure and flow. However, while valvular interstitial cell-secreted matrix metalloproteinases are considered the primary effectors of collagen catabolism, the mechanisms by which damaged collagen fibers are selectively degraded remain unclear. Growing evidence suggests that the collagen fiber strain state plays a key role, with the strain-dependent configuration of the collagen molecules either masking or presenting proteolytic sites, thereby protecting or accelerating collagen proteolysis. In this study, the effects of equibiaxial strain state on collagen catabolism were investigated in porcine aortic valve and pulmonary valve tissues. Bacterial collagenase (0.2 and 0.5 mg/mL) was utilized to simulate endogenous matrix metalloproteinases, and biaxial stress relaxation and biochemical collagen concentration served as functional and compositional measures of collagen catabolism, respectively. At a collagenase concentration of 0.5 mg/mL, increasing the equibiaxial strain imposed during stress relaxation (0%, 37.5%, and 50%) yielded significantly lower median collagen concentrations in the aortic valve (p = 0.0231) and pulmonary valve (p = 0.0183), suggesting that relatively large strain magnitudes may enhance collagen catabolism. Collagen concentration decreases were paralleled by trends of accelerated normalized stress relaxation rate with equibiaxial strain in aortic valve tissues. Collectively, these in vitro results indicate that biaxial strain state is capable of affecting the susceptibility of valvular collagens to catabolism, providing a basis for further investigation of

  13. In vivo imaging of dermal collagen in skin burn by collagen-sensitive second-harmonic-generation microscopy

    Science.gov (United States)

    Yasui, Takeshi; Tanaka, Ryosuke; Hase, Eiji; Fukushima, Shu-ichiro; Araki, Tsutomu

    2013-02-01

    Optical assessment of skin burns is possible with second-harmonic-generation (SHG) microscopy due to its high sensitivity to thermal denaturation of collagen molecules. In contrast to previous studies that were performed using excised tissue specimens ex vivo, in this study, we demonstrated in vivo observation of dermal collagen fibers in living rat burn models with SHG microscopy. We confirmed that changes in SHG vanishing patterns in the SHG images depended on the burn degree. The results imply that SHG microscopy can be used as a low-invasiveness, highly quantitative tool for skin burn assessment.

  14. Collagen films with stabilized liquid crystalline phases and concerns on osteoblast behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Minjian; Ding, Shan; Min, Xiang; Jiao, Yanpeng, E-mail: tjiaoyp@jnu.edu.cn; Li, Lihua; Li, Hong; Zhou, Changren, E-mail: tcrz9@jnu.edu.cn

    2016-01-01

    To duplicate collagen's in vivo liquid crystalline (LC) phase and investigate the relationship between the morphology of LC collagen and osteoblast behavior, a self-assembly method was introduced for preparing collagen films with a stabilized LC phase. The LC texture and topological structure of the films before and after stabilization were observed with polarizing optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The relationship between the collagen films and osteoblast behavior was studied with the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide method, proliferation index detection, alkaline phosphatase measurements, osteocalcin assay, inverted microscopy, SEM observation, AFM observation, and cytoskeleton fluorescence staining. The results showed that the LC collagen film had continuously twisting orientations in the cholesteric phase with a typical series of arced patterns. The collagen fibers assembled in a well-organized orientation in the LC film. Compared to the non-LC film, the LC collagen film can promote cell proliferation, and increase ALP and osteocalcin expression, revealing a contact guide effect on osteoblasts. - Highlights: • Collagen film with liquid crystalline (LC) phase was observed by POM, SEM and AFM. • The effect of LC collagen film on osteoblasts behaviors was studied in detail. • LC collagen film promoted osteoblast proliferation and osteogenesis activity.

  15. Hierarchical model of fibrillar collagen distribution for polarization-resolved SHG microscopy

    Science.gov (United States)

    Tuer, Adam E.; Akens, Margarete K.; Krouglov, Serguei; Sandkuijl, Daaf; Wilson, Brian C.; Whyne, Cari M.; Barzda, Virginijus

    2013-02-01

    A hierarchical model of the organization of fibrillar collagen is developed and its implications on polarization-resolved second harmonic generation (SHG) microscopy are investigated. A "ground-up" approach is employed to develop the theory for understanding of the origin of SHG from fibrillar collagen. The effects of fibril ultrastructure and fibril macroscopic organization on the second-order polarization properties of fibrillar collagen are presented in conjunction with recent ab initio results performed on a collagen triple-helix model (-GLY-PRO-HYP-)n. Various tissues containing fibrillar collagen are quantified using a polarization-resolved SHG technique, termed polarization-in, polarization-out (PIPO) and interpreted in light of the aforementioned theory. The method involves varying the incident laser polarization, while monitoring the SHG intensity through an analyzer. From the SHG polarization data the orientation of the fibers, in biological tissue, can be deduced. Unique PIPO signatures are observed for different rat tissues and interpreted in terms of the collagen composition, fibril ultrastructure, and macroscopic organization. Similarities and discrepancies in the second-order polarization properties of different collagen types and ultrastructures will be presented. PIPO SHG microscopy shows promise in its ability to quantify the organization of collagen in various tissues. The ability to characterize the structure of collagen in various tissue microenvironments will aid in the study of numerous collagen related biological process, including tissue diseases, wound repair, and tumor development and progression.

  16. Discoidin domain receptor 2 regulates the adhesion of fibroblasts to 3D collagen matrices.

    Science.gov (United States)

    Kim, Daehwan; You, Eunae; Min, Na Young; Lee, Kwang-Ho; Kim, Hyoung Kyu; Rhee, Sangmyung

    2013-05-01

    The collagen matrix constitutes the primary extracellular matrix (ECM) portion of mammalian connective tissues in which the interaction of the cell and the surrounding collagen fibers has a significant impact on cell and tissue physiology, including morphogenesis, development and motility. Discoidin domain receptors (DDR1 and DDR2) have been identified as the receptor tyrosine kinases that are activated upon collagen binding. However, there is a lack of evidence regarding the effect of DDRs on the mechanical interaction between fibroblasts and ECM. In this study, we demonstrated that one of the major phosphotyrosine proteins in human fibroblasts during 3D collagen matrix polymerization is DDR2. Treatment of fibroblasts in 3D collagen matrices with platelet-derived growth factor (PDFG) has been shown to increase DDR2 phosphorylation. Silencing of DDR2 with siRNA in fibroblasts significantly reduced the number of dendritic extensions regardless of whether cells were cultured in the collagen or fibronectin 3D matrices. Decreasing dendritic extensions in DDR2-silenced cells has also been shown to decrease the ability of fibroblast entanglement to collagen fibrils in 3D collagen matrices. Finally, we also showed that the silencing of DDR2 decreased the cell migration in 3D nested collagen matrices but had no effect on 3D floating matrix contraction. Collectively, these results suggest that DDR2 functioning is required for the membrane dynamics to control the mechanical attachment of fibroblasts to the 3D collagen matrices in an integrin-independent manner.

  17. Stromal fibers in oral squamous cell carcinoma: A possible new prognostic indicator?

    Science.gov (United States)

    Kardam, Priyanka; Mehendiratta, Monica; Rehani, Shweta; Kumra, Madhumani; Sahay, Khushboo; Jain, Kanu

    2016-01-01

    Background: Many studies have been carried out to study the role of extracellular matrix proteins, growth factors and matrix metalloproteinases on tumor invasion. However, literature related to the analysis of connective tissue fibers in varying grades of oral squamous cell carcinoma (OSCC) is very limited. Aim: To analyze the changes in collagen and elastic fibers in varying grades of (OSCC). Settings and Design: This retrospective study was carried out using a light and polarizing microscope. Materials and Methods: Three sections each were cut from fifty samples of varying grades of OSCC and ten samples of control followed by staining with H and E, Picrosirius-Red and Verhoeff–Van Gieson. Qualitative and quantitative analysis of collagen and elastic fibers were accomplished using set criteria. Statistical Analysis: Data were entered into the Statistical Package for Social Sciences (SPSS) version 13.5 for analysis. Results: A change in colors of collagen fibers was seen on progressing from well to poorly differentiated OSCC. Thin collagen fibers predominantly exhibited greenish yellow, but the thick fibers exhibited a variety of colors. As the grade of OSCC progressed, collagen fibers were loosely packed haphazardly arranged. Statistically insignificant results were obtained for quantitative analysis of collagen and qualitative analysis of elastic fibers. Conclusion: The collagen fibers undergo a change in color, orientation and packing in the stroma of varying grades of OSCC. The uniqueness of this study lies in the exploration of elastic fibers in OSCC which has not been done so far. PMID:27721605

  18. Quantification of aortic and cutaneous elastin and collagen morphology in Marfan syndrome by multiphoton microscopy.

    Science.gov (United States)

    Cui, Jason Z; Tehrani, Arash Y; Jett, Kimberly A; Bernatchez, Pascal; van Breemen, Cornelis; Esfandiarei, Mitra

    2014-09-01

    In a mouse model of Marfan syndrome, conventional Verhoeff-Van Gieson staining displays severe fragmentation, disorganization and loss of the aortic elastic fiber integrity. However, this method involves chemical fixatives and staining, which may alter the native morphology of elastin and collagen. Thus far, quantitative analysis of fiber damage in aorta and skin in Marfan syndrome has not yet been explored. In this study, we have used an advanced noninvasive and label-free imaging technique, multiphoton microscopy to quantify fiber fragmentation, disorganization, and total volumetric density of aortic and cutaneous elastin and collagen in a mouse model of Marfan syndrome. Aorta and skin samples were harvested from Marfan and control mice aged 3-, 6- and 9-month. Elastin and collagen were identified based on two-photon excitation fluorescence and second-harmonic-generation signals, respectively, without exogenous label. Measurement of fiber length indicated significant fragmentation in Marfan vs. control. Fast Fourier transform algorithm analysis demonstrated markedly lower fiber organization in Marfan mice. Significantly reduced volumetric density of elastin and collagen and thinner skin dermis were observed in Marfan mice. Cutaneous content of elastic fibers and thickness of dermis in 3-month Marfan resembled those in the oldest control mice. Our findings of early signs of fiber degradation and thinning of skin dermis support the potential development of a novel non-invasive approach for early diagnosis of Marfan syndrome.

  19. Collagen Architecture of the Posterior Pole: High-Resolution Wide Field of View Visualization and Analysis Using Polarized Light Microscopy

    Science.gov (United States)

    Jan, Ning-Jiun; Lathrop, Kira; Sigal, Ian A.

    2017-01-01

    Purpose The purpose of this study was to leverage polarized light microscopy (PLM) to visualize the collagen fiber architecture of posterior pole and optic nerve head with micrometer-scale resolution and to identify and quantify major organizational components. Methods Eight sheep posterior poles were cryosectioned and imaged using PLM. Collagen fiber orientation was determined by using custom scripts, and the resulting orientation maps were inspected and quantified to identify major structural elements and tested for differences in mean fiber orientation and anisotropy, using linear mixed effect models. Results Images revealed an intricate organization of collagen fibers in the posterior pole. In the lamina cribrosa, interweaving fibers formed large knots and wrapped around nerve fiber pores, with beam insertions into the scleral canal wall that were either narrow and straight or wide. In the peripapillary sclera, three significantly different (P PLM revealed structural aspects of the lamina cribrosa and sclera that may have important biomechanical roles but that were previously unreported or not characterized quantitatively. In the lamina cribrosa, these roles included wide and narrow beam insertions and details of collagen fibers interweaving and wrapping around the pores. In the sclera, we described regions of circumferential, radial, and unaligned “random” fibers. Although there is consensus that circumferential fibers protect neural tissues by resisting canal expansion, the role of the radial fibers remains unclear. PMID:28146238

  20. Collagen Architecture of the Posterior Pole: High-Resolution Wide Field of View Visualization and Analysis Using Polarized Light Microscopy.

    Science.gov (United States)

    Jan, Ning-Jiun; Lathrop, Kira; Sigal, Ian A

    2017-02-01

    The purpose of this study was to leverage polarized light microscopy (PLM) to visualize the collagen fiber architecture of posterior pole and optic nerve head with micrometer-scale resolution and to identify and quantify major organizational components. Eight sheep posterior poles were cryosectioned and imaged using PLM. Collagen fiber orientation was determined by using custom scripts, and the resulting orientation maps were inspected and quantified to identify major structural elements and tested for differences in mean fiber orientation and anisotropy, using linear mixed effect models. Images revealed an intricate organization of collagen fibers in the posterior pole. In the lamina cribrosa, interweaving fibers formed large knots and wrapped around nerve fiber pores, with beam insertions into the scleral canal wall that were either narrow and straight or wide. In the peripapillary sclera, three significantly different (P narrow beam insertions and details of collagen fibers interweaving and wrapping around the pores. In the sclera, we described regions of circumferential, radial, and unaligned "random" fibers. Although there is consensus that circumferential fibers protect neural tissues by resisting canal expansion, the role of the radial fibers remains unclear.

  1. 胶原纤维为模板介孔TiO_2和Pt掺杂TiO_2纤维的制备及光催化降解黑液(英文)%Preparation of Mesoporous TiO2 and Pt-Doped TiO2 Fibers with Collagen Fiber as a Template and Their Performance for Photocatalytic Degradation of Black Liquor

    Institute of Scientific and Technical Information of China (English)

    蔡莉

    2012-01-01

    以胶原纤维为模板,Ti(SO4)2为钛源,合成了新型光催化剂—介孔TiO2和Pt掺杂TiO2纤维。通过场发射扫描电镜(FESEM)、比表面积和孔径分析、紫外–可见光谱和分子荧光光谱等检测手段对两种介孔TiO2纤维的结构和物理性能进行了表征。FESEM分析表明,胶原纤维的表面结构能被较好地保留在介孔TiO2和Pt掺杂TiO2纤维中。N2吸附–脱附等温线为IV型,表明TiO2和Pt掺杂TiO2纤维具有介孔结构。基于结构的特点,在可见光和UV-A激发下,介孔TiO2和Pt掺杂TiO2纤维表现出强于商品级纳米TiO2(Degussa P25)的总有机碳(TOC)脱除率。此外,Pt的掺杂能明显改善介孔TiO2的光催化活性。光催化实验表明,Pt掺杂TiO2纤维(1.0g L–1)在可见光照射420 min后,黑液的TOC脱除率为37%;UV-A(360 nm)照射300min后,TOC脱除率为51%。因此,制备的介孔TiO2和Pt掺杂TiO2纤维作为一类性能优异的光催化剂,能用于黑液的光催化降解,并在其他类似的反应条件下具有潜在的应用前景。%The mesoporous TiO2 and Pt-doped TiO2 fibers as a catalyst were prepared with collagen fiber as a template and Ti(SO4)2 as a titanium source.Their structure and physical properties were characterized by field emission scanning electron microscopy(FESEM),specific surface area analysis,UV–Vis absorption spectra and photoluminescence spectra(PL) as well.The FESEM analysis indicated that the well-defined surface morphology of natural collagen fiber was mostly preserved in TiO2 and Pt-doped TiO2 fibers.The N2 adsorption/desorption isotherms of TiO2 and Pt-doped TiO2 fibers were typical type IV due to the characteristics of mesoporous materials.The mesoporous TiO2 and Pt-doped TiO2 fibers revealed a higher total organic carbon(TOC) removal rate of black liquor under visible light and UV-A light irradiation,compared to commercial nano-TiO2(Degussa P25).In addition,the photocatalytic activity of mesoporous

  2. Collagen Microstructure in the Vocal Ligament: Initial Results on the Potential Effects of Smoking

    Science.gov (United States)

    Kelleher, Jordan E.; Siegmund, Thomas; Chan, Roger W.

    2014-01-01

    Objective This investigation quantitatively characterizes the collagenous microstructure of human vocal ligament specimens excised postmortem from non-smokers and smokers. Study Design Retrospective Cohort Study Methods Second harmonic generation (SHG) imaging was performed at three anatomical locations of vocal ligament specimens: anterior, mid-membranous, and posterior regions. Two microstructural parameters were extracted from the SHG images: (1) normalized fiber density, and (2) fiber dispersion coefficient, quantifying the degree of collagen fiber dispersion about a preferred direction. Results For both the non-smoker and smoker subjects, the fiber dispersion coefficient was heterogeneous. Differences in the collagenous structure of non-smokers and smoker subjects were pronounced at the mid-membranous location. However, the directionality of the heterogeneity in the smoker subjects was opposite to that in the non-smoker subjects. Specifically, the fiber dispersion coefficient in the non-smoker subjects was lower in the midmembranous region (indicating more fiber alignment) than at the anterior/posterior regions, but for the smoker subjects the fiber dispersion coefficient was higher at the mid-membranous region. The normalized fiber density was near constant in the non-smoker subjects, but the smoker subjects had fewer fibers in the mid-membranous region than at the anterior/posterior regions. Conclusion Spatial microstructural variations may exist in the vocal fold ligament both in non-smokers and smokers. Smoking appears to influence the degree and direction of microstructure heterogeneity in the vocal fold ligament. PMID:24473992

  3. Collagen self-assembly and the development of tendon mechanical properties.

    Science.gov (United States)

    Silver, Frederick H; Freeman, Joseph W; Seehra, Gurinder P

    2003-10-01

    The development of the musculoskeleton and the ability to locomote requires controlled cell division as well as spatial control over deposition of extracellular matrix. Self-assembly of procollagen and its final processing into collagen fibrils occurs extracellularly. The formation of crosslinked collagen fibers results in the conversion of weak liquid-like embryonic tissues to tough elastic solids that can store energy and do work. Collagen fibers in the form of fascicles are the major structural units found in tendon. The purpose of this paper is to review the literature on collagen self-assembly and tendon development and to relate this information to the development of elastic energy storage in non-mineralizing and mineralizing tendons. Of particular interest is the mechanism by which energy is stored in tendons during locomotion. In vivo, collagen self-assembly occurs by the deposition of thin fibrils in recesses within the cell membrane. These thin fibrils later grow in length and width by lateral fusion of intermediates. In vitro, collagen self-assembly occurs by both linear and lateral growth steps with parallel events seen in vivo; however, in the absence of cellular control and enzymatic cleavage of the propeptides, the growth mechanism is altered, and the fibrils are irregular in cross section. Results of mechanical studies suggest that prior to locomotion the mechanical response of tendon to loading is dominated by the viscous sliding of collagen fibrils. In contrast, after birth when locomotion begins, the mechanical response is dominated by elastic stretching of crosslinked collagen molecules.

  4. Second harmonic generation microscopy differentiates collagen type I and type III in COPD

    Science.gov (United States)

    Suzuki, Masaru; Kayra, Damian; Elliott, W. Mark; Hogg, James C.; Abraham, Thomas

    2012-03-01

    The structural remodeling of extracellular matrix proteins in peripheral lung region is an important feature in chronic obstructive pulmonary disease (COPD). Multiphoton microscopy is capable of inducing specific second harmonic generation (SHG) signal from non-centrosymmetric structural proteins such as fibrillar collagens. In this study, SHG microscopy was used to examine structural remodeling of the fibrillar collagens in human lungs undergoing emphysematous destruction (n=2). The SHG signals originating from these diseased lung thin sections from base to apex (n=16) were captured simultaneously in both forward and backward directions. We found that the SHG images detected in the forward direction showed well-developed and well-structured thick collagen fibers while the SHG images detected in the backward direction showed striking different morphological features which included the diffused pattern of forward detected structures plus other forms of collagen structures. Comparison of these images with the wellestablished immunohistochemical staining indicated that the structures detected in the forward direction are primarily the thick collagen type I fibers and the structures identified in the backward direction are diffusive structures of forward detected collagen type I plus collagen type III. In conclusion, we here demonstrate the feasibility of SHG microscopy in differentiating fibrillar collagen subtypes and understanding their remodeling in diseased lung tissues.

  5. Quantitative regulation of bone-mimetic, oriented collagen/apatite matrix structure depends on the degree of osteoblast alignment on oriented collagen substrates.

    Science.gov (United States)

    Matsugaki, Aira; Isobe, Yoshihiro; Saku, Taro; Nakano, Takayoshi

    2015-02-01

    Bone tissue has a specific anisotropic morphology derived from collagen fiber alignment and the related apatite crystal orientation as a bone quality index. However, the precise mechanism of cellular regulation of the crystallographic orientation of apatite has not been clarified. In this study, anisotropic construction of cell-produced mineralized matrix in vitro was established by initiating organized cellular alignment and subsequent oriented bone-like matrix (collagen/apatite) production. The oriented collagen substrates with three anisotropic levels were prepared by a hydrodynamic method. Primary osteoblasts were cultured on the fabricated substrates until mineralized matrix formation is confirmed. Osteoblast alignment was successfully regulated by the level of substrate collagen orientation, with preferential alignment along the direction of the collagen fibers. Notably, both fibrous orientation of newly synthesized collagen matrix and c-axis of produced apatite crystals showed preferential orientation along the cell direction. Because the degree of anisotropy of the deposited apatite crystals showed dependency on the directional distribution of osteoblasts cultured on the oriented collagen substrates, the cell orientation determines the crystallographic anisotropy of produced apatite crystals. To the best of our knowledge, this is the first report demonstrating that bone tissue anisotropy, even the alignment of apatite crystals, is controllable by varying the degree of osteoblast alignment via regulating the level of substrate orientation.

  6. The influence of low-level laser therapy on biomodulation of collagen and elastic fibers A influência da terapia a laser de baixa densidade de energia na biomodulação das fibras colágenas e elásticas

    Directory of Open Access Journals (Sweden)

    Lívia Souza Pugliese

    2003-12-01

    Full Text Available The study of low-level laser therapy upon extracellular matrix elements is important to understand the wound healing process under this agent. However, little is known about the interference of laser light in relation to collagen and elastic fibers. Cutaneous wounds were performed on the back of 72 Wistar rats and a Ga-Al-As low-level laser was punctually applied with different energy densities. The animals were killed after 24, 48, 72 hours and 5, 7 and 14 days. Tissues were stained with hematoxilin-eosin, sirius red fast green and orcein and then analyzed. It was observed that the treated group exhibited larger reduction of edema and inflammatory infiltrate. The treated animals presented a larger expression of collagen and elastic fibers, although without statistical significance (p > 0.05. Treatment with a dosage of 4 J/cm² exhibited more expressive results than that with 8 J/cm². In this study, the authors concluded that low-level laser therapy contributed to a larger expression of collagen and elastic fibers during the early phases of the wound healing process.O estudo da terapia a laser de baixa densidade de energia sobre os diversos constituintes da matriz extracelular é crucial para o entendimento do processo cicatricial sob esse agente. Todavia, pouco se sabe sobre a interferência do laser em relação às fibras colágenas e elásticas. Realizaram-se ferimentos cutâneos padronizados no dorso de setenta e dois ratos Wistar e, em seguida, aplicação pontual do raio laser de baixa potência do tipo Arseneto de Gálio-Alumínio (Ga-Al-As com diferentes densidades de energia. Os animais foram sacrificados com 24, 48 e 72 horas e aos 5, 7 e 14 dias. Procedeu-se à análise das secções teciduais coradas por hematoxilina-eosina, sírius vermelho e orceína. Observou-se, que nos grupos submetidos à terapia a laser, houve maior redução do edema e infiltrado inflamatório. Os animais tratados apresentaram uma maior expressão de fibras

  7. Collagen and Its Role in predicting the Biological Behavior of Odontogenic Lesions.

    Science.gov (United States)

    Kulkarni, Pavan G; Kumari, M Aruna; Jahagirdar, Abhishek; Nandan, Srk; Reddy D, Shyam Prasad; Keerthi, M

    2017-02-01

    Odontogenic cysts and tumors have variable recurrence rates. Recurrence rate is mainly due to the activity of the epithelium. The epithelium of these lesions has been investigated extensively in regard to their role in proliferative and aggressive behavior of the lesions. However, the role of the connective tissue wall in their behavior has not been studied as extensively. Collagen is an essential part of the connective tissue as a whole and fibrous wall of cystic lesions especially. It is demonstrated by picrosirius red dye staining combined with polarization microscopy. This method permits the evaluation of the nature of the collagen fibers in addition to their thickness. A total of 56 histopathologically diagnosed cases comprising odontogenic follicle, dentigerous cyst, unicystic ameloblastoma, keratocystic odontogenic tumor (KCOT), multicystic/solid ameloblastoma, and ameloblastic carcinoma were taken and stained using picrosirius red stain and evaluated using a polarizing microscope. Collagen fibers in odontogenic follicles and dentiger-ous cysts showed predominant orange-red birefringence; fibers in unicystic ameloblastoma and KCOT showed both orange red and greenish-yellow birefringence; and fibers of multicystic/ solid ameloblastoma showed predominant greenish-yellow birefringence and ameloblastic carcinoma that showed almost complete greenish birefringence. As the biological behavior of the lesions in the spectrum studied progress toward aggressive nature, increase in immature collagen fibers is noticed. This study suggests that the nature of collagen fibers plays a pivotal role in predicting the biological behavior of odontogenic lesions. Aggressive nature of the odontogenic lesions is determined by both the epithelium and the connective tissue components (collagen). Studying the nature and type of collagen helps in predicting its biological behavior.

  8. Primary hepatocyte culture in collagen gel mixture and collagen sandwich

    Institute of Scientific and Technical Information of China (English)

    Ying-Jie Wang; Hong-Ling Liu; Hai-Tao Guo; Hong-Wei Wen; Jun Liu

    2004-01-01

    AIM: To explore the methods of hepatocytes culture in a collagen gel mixture or between double layers of collagen sandwich configuration and to examine the functional and cytomorphological characteristics of cultured hepatocytes.METHODS: A two-step collagenase perfusion technique was used to isolate the hepatocytes from Wistar rats or newborn Chinese experimental piglets. The isolated hepatocytes were cultured in a collagen gel mixture or between double layers of collagen sandwich configuration respectively. The former was that rat hepatocytes were mixed with type I rat tail collagen solution till gelled, and the medium was added onto the gel. The latter was that swine hepatocytes were seeded on a plate precoated with collagen gel for 24 h, then another layer of collagen gel was overlaid, resulting in a sandwich configuration. The cytomorphological characteristics, albumin secretion, and LDH-release of the hepatocytes cultured in these two models were examined.RESULTS: Freshly isolated rat hepatocytes were successfully mixed and fixed in collagen gel, and cultured in the gel condition. During the culture period, the urea synthesized and secreted by rat hepatocytes was detected throughout the period. Likewise, newborn experimental piglet hepatocytes were successfully fixed between the double layers of collagen gel, forming a sandwich configuration.Within a week of culture, the albumin secreted by swine hepatocytes was detected by SDS/PAGE analysis. The typical cytomorphological characteristics of the hepatocytes cultured by the above two culture models were found under a phasecontrast microscope. There was little LDH-release during the culture period.CONCLUSION: Both collagen gel mixture and double layers of collagen sandwich configuration can provide cultural conditions much closer to in vivoenvironment, and are helpful for maintaining specific hepatic fiJnctions and cytomorphological characteristics. A collagen gel mixture culture may be more eligible for the

  9. Polarized Raman anisotropic response of collagen in tendon: towards 3D orientation mapping of collagen in tissues.

    Science.gov (United States)

    Galvis, Leonardo; Dunlop, John W C; Duda, Georg; Fratzl, Peter; Masic, Admir

    2013-01-01

    In this study, polarized Raman spectroscopy (PRS) was used to characterize the anisotropic response of the amide I band of collagen as a basis for evaluating three-dimensional collagen fibril orientation in tissues. Firstly, the response was investigated theoretically by applying classical Raman theory to collagen-like peptide crystal structures. The theoretical methodology was then tested experimentally, by measuring amide I intensity anisotropy in rat tail as a function of the orientation of the incident laser polarization. For the theoretical study, several collagen-like triple-helical peptide crystal structures obtained from the Protein Data Bank were rotated "in plane" and "out of plane" to evaluate the role of molecular orientation on the intensity of the amide I band. Collagen-like peptides exhibit a sinusoidal anisotropic response when rotated "in plane" with respect to the polarized incident laser. Maximal intensity was obtained when the polarization of the incident light is perpendicular to the molecule and minimal when parallel. In the case of "out of plane" rotation of the molecular structure a decreased anisotropic response was observed, becoming completely isotropic when the structure was perpendicular to the plane of observation. The theoretical Raman response of collagen was compared to that of alpha helical protein fragments. In contrast to collagen, alpha helices have a maximal signal when incident light is parallel to the molecule and minimal when perpendicular. For out-of-plane molecular orientations alpha-helix structures display a decreased average intensity. Results obtained from experiments on rat tail tendon are in excellent agreement with the theoretical predictions, thus demonstrating the high potential of PRS for experimental evaluation of the three-dimensional orientation of collagen fibers in biological tissues.

  10. Polarized Raman anisotropic response of collagen in tendon: towards 3D orientation mapping of collagen in tissues.

    Directory of Open Access Journals (Sweden)

    Leonardo Galvis

    Full Text Available In this study, polarized Raman spectroscopy (PRS was used to characterize the anisotropic response of the amide I band of collagen as a basis for evaluating three-dimensional collagen fibril orientation in tissues. Firstly, the response was investigated theoretically by applying classical Raman theory to collagen-like peptide crystal structures. The theoretical methodology was then tested experimentally, by measuring amide I intensity anisotropy in rat tail as a function of the orientation of the incident laser polarization. For the theoretical study, several collagen-like triple-helical peptide crystal structures obtained from the Protein Data Bank were rotated "in plane" and "out of plane" to evaluate the role of molecular orientation on the intensity of the amide I band. Collagen-like peptides exhibit a sinusoidal anisotropic response when rotated "in plane" with respect to the polarized incident laser. Maximal intensity was obtained when the polarization of the incident light is perpendicular to the molecule and minimal when parallel. In the case of "out of plane" rotation of the molecular structure a decreased anisotropic response was observed, becoming completely isotropic when the structure was perpendicular to the plane of observation. The theoretical Raman response of collagen was compared to that of alpha helical protein fragments. In contrast to collagen, alpha helices have a maximal signal when incident light is parallel to the molecule and minimal when perpendicular. For out-of-plane molecular orientations alpha-helix structures display a decreased average intensity. Results obtained from experiments on rat tail tendon are in excellent agreement with the theoretical predictions, thus demonstrating the high potential of PRS for experimental evaluation of the three-dimensional orientation of collagen fibers in biological tissues.

  11. Quantifying collagen structure in breast biopsies using second-harmonic generation imaging.

    Science.gov (United States)

    Ambekar, Raghu; Lau, Tung-Yuen; Walsh, Michael; Bhargava, Rohit; Toussaint, Kimani C

    2012-09-01

    Quantitative second-harmonic generation imaging is employed to assess stromal collagen in normal, hyperplastic, dysplastic, and malignant breast tissues. The cellular scale organization is quantified using Fourier transform-second harmonic generation imaging (FT-SHG), while the molecular scale organization is quantified using polarization-resolved second-harmonic generation measurements (P-SHG). In the case of FT-SHG, we apply a parameter that quantifies the regularity in collagen fiber orientation and find that malignant tissue contains locally aligned fibers compared to other tissue conditions. Alternatively, using P-SHG we calculate the ratio of tensor elements (d(15)/d(31), d(22)/d(31), and d(33)/d(31)) of the second-order susceptibility χ(2) for collagen fibers in breast biopsies. In particular, d(15)/d(31) shows potential differences across the tissue pathology. We also find that trigonal symmetry (3m) is a more appropriate model to describe collagen fibers in malignant tissues as opposed to the conventionally used hexagonal symmetry (C6). This novel method of targeting collagen fibers using a combination of two quantitative SHG techniques, FT-SHG and P-SHG, holds promise for breast tissue analysis and applications to characterizing cancer in a manner that is compatible with clinical practice.

  12. UV damage of collagen: insights from model collagen peptides.

    Science.gov (United States)

    Jariashvili, Ketevan; Madhan, Balaraman; Brodsky, Barbara; Kuchava, Ana; Namicheishvili, Louisa; Metreveli, Nunu

    2012-03-01

    Fibrils of Type I collagen in the skin are exposed to ultraviolet (UV) light and there have been claims that collagen photo-degradation leads to wrinkles and may contribute to skin cancers. To understand the effects of UV radiation on collagen, Type I collagen solutions were exposed to the UV-C wavelength of 254 nm for defined lengths of time at 4°C. Circular dichroism (CD) experiments show that irradiation of collagen leads to high loss of triple helical content with a new lower thermal stability peak and SDS-gel electrophoresis indicates breakdown of collagen chains. To better define the effects of UV radiation on the collagen triple-helix, the studies were extended to peptides which model the collagen sequence and conformation. CD studies showed irradiation for days led to lower magnitudes of the triple-helix maximum at 225 nm and lower thermal stabilities for two peptides containing multiple Gly-Pro-Hyp triplets. In contrast, the highest radiation exposure led to little change in the T(m) values of (Gly-Pro-Pro)(10) and (Ala-Hyp-Gly)(10) , although (Gly-Pro-Pro)(10) did show a significant decrease in triple helix intensity. Mass spectroscopy indicated preferential cleavage sites within the peptides, and identification of some of the most susceptible sites of cleavage. The effect of radiation on these well defined peptides gives insight into the sequence and conformational specificity of photo-degradation of collagen.

  13. Shining light on collagen: expressing collagen in plants.

    Science.gov (United States)

    Brodsky, Barbara; Kaplan, David L

    2013-07-01

    Collagens are a remarkable group of proteins that are critical from a physiological perspective due to their diverse and versatile functions in vivo. However, collagens are challenging to generate ex vivo for biomaterials or regenerative medicine due to their complex processing and assembly into functional materials. Therefore, collagen availability remains a major unmet need for biomaterials, as relatively limited supplies of the protein in pure form are available mainly through harvesting bovine tissues. This animal source, subsequent to purification, remains associated with significant safety concerns due to the potential carryover of animal-derived diseases. Other more limited sources of animal collagens are also commercially available, as well as collagens generated in heterologous hosts; however, the challenge to these sources remains both economic and structural. The need for new safe sources of collagens remains high, with a significant potential impact in areas of medicine when considering the opportunity to mimic native collagen features. The articles in this issue of the journal focus on plant-derived collagens to address some of these needs. Progress toward plant production of collagens, the ability to self-assemble these recombinant proteins into higher-order structures, and the utility of these materials in various medical applications suggest an important path forward for the field.

  14. Quantitative Characterization of Collagen in the Fibrotic Capsule Surrounding Implanted Polymeric Microparticles through Second Harmonic Generation Imaging.

    Directory of Open Access Journals (Sweden)

    Dana Akilbekova

    Full Text Available The collagenous capsule formed around an implant will ultimately determine the nature of its in vivo fate. To provide a better understanding of how surface modifications can alter the collagen orientation and composition in the fibrotic capsule, we used second harmonic generation (SHG microscopy to evaluate collagen organization and structure generated in mice subcutaneously injected with chemically functionalized polystyrene particles. SHG is sensitive to the orientation of a molecule, making it a powerful tool for measuring the alignment of collagen fibers. Additionally, SHG arises from the second order susceptibility of the interrogated molecule in response to the electric field. Variation in these tensor components distinguishes different molecular sources of SHG, providing collagen type specificity. Here, we demonstrated the ability of SHG to differentiate collagen type I and type III quantitatively and used this method to examine fibrous capsules of implanted polystyrene particles. Data presented in this work shows a wide range of collagen fiber orientations and collagen compositions in response to surface functionalized polystyrene particles. Dimethylamino functionalized particles were able to form a thin collagenous matrix resembling healthy skin. These findings have the potential to improve the fundamental understanding of how material properties influence collagen organization and composition quantitatively.

  15. Insight into the collagen assembly in the presence of lysine and glutamic acid: An in vitro study.

    Science.gov (United States)

    Liu, Xinhua; Dan, Nianhua; Dan, Weihua

    2017-01-01

    The aim of this study is to evaluate the effects of two different charged amino acids in collagen chains, lysine and glutamic acid, on the fibrillogenesis process of collagen molecules. The turbidity, zeta potential, and fiber diameter analysis suggest that introducing the positively charged lysine into collagen might improve the sizes or amounts of the self-assembled collagen fibrils significantly. Conversely, the negatively charged glutamic acid might restrict the self-assembly of collagen building blocks into a higher order structure. Meanwhile, the optimal fibrillogenesis condition is achieved when the concentration of lysine reaches to 1mM. Both scanning electron microscopy (SEM) and atomic force microscope (AFM) analysis indicates that compared to pure collagen fibrils, the reconstructed collagen-lysine co-fibrils exhibit a higher degree of inter-fiber entanglements with more straight and longer fibrils. Noted that the specific D-period patterns of the reconstructed collagen fibrils could be clearly discernible and the width of D-banding increases steadily after introducing lysine. Besides, the kinetic and thermodynamic collagen self-assembly analysis confirms that the rate constants of both the first and second assembly phase decrease after introducing lysine, and lysine could promote the process of collagen fibrillogenesis obeying the laws of thermodynamics. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Automated quantification of aligned collagen for human breast carcinoma prognosis

    Directory of Open Access Journals (Sweden)

    Jeremy S Bredfeldt

    2014-01-01

    Full Text Available Background: Mortality in cancer patients is directly attributable to the ability of cancer cells to metastasize to distant sites from the primary tumor. This migration of tumor cells begins with a remodeling of the local tumor microenvironment, including changes to the extracellular matrix and the recruitment of stromal cells, both of which facilitate invasion of tumor cells into the bloodstream. In breast cancer, it has been proposed that the alignment of collagen fibers surrounding tumor epithelial cells can serve as a quantitative image-based biomarker for survival of invasive ductal carcinoma patients. Specific types of collagen alignment have been identified for their prognostic value and now these tumor associated collagen signatures (TACS are central to several clinical specimen imaging trials. Here, we implement the semi-automated acquisition and analysis of this TACS candidate biomarker and demonstrate a protocol that will allow consistent scoring to be performed throughout large patient cohorts. Methods: Using large field of view high resolution microscopy techniques, image processing and supervised learning methods, we are able to quantify and score features of collagen fiber alignment with respect to adjacent tumor-stromal boundaries. Results: Our semi-automated technique produced scores that have statistically significant correlation with scores generated by a panel of three human observers. In addition, our system generated classification scores that accurately predicted survival in a cohort of 196 breast cancer patients. Feature rank analysis reveals that TACS positive fibers are more well-aligned with each other, are of generally lower density, and terminate within or near groups of epithelial cells at larger angles of interaction. Conclusion: These results demonstrate the utility of a supervised learning protocol for streamlining the analysis of collagen alignment with respect to tumor stromal boundaries.

  17. Arterial calcification: Conscripted by collagen

    Science.gov (United States)

    Miller, Jordan D.

    2016-03-01

    In atherosclerotic plaques, patterns of calcification -- which have profound implications for plaque stability and vulnerability to rupture -- are determined by the collagen's content and patterning throughout the plaque.

  18. Biological behavior of fibroblast on contractile collagen hydrogel crosslinked by γ-irradiation.

    Science.gov (United States)

    Zhang, Xiangmei; Zhang, Yaqing; Chen, Wenqiang; Xu, Ling; Wei, Shicheng; Zheng, Yufeng; Zhai, Maolin

    2014-08-01

    Collagen hydrogels exhibited a contractile trend in simulated body fluid. In this study, the internal pore architecture and mechanical properties of collagen hydrogel prepared by radiation crosslinking was evaluated during contraction, and the effect of contractile collagen hydrogels on the biological behavior of fibroblasts were investigated in vitro, such as viability, proliferation, morphology, apoptosis, cycle, and stress fiber. The results showed that accompany with contraction of collagen hydrogel, the pore diameter of the hydrogels decreased and compressive modulus increased. However, fibroblasts can grow on contractile collagen hydrogels. Indeed, collagen hydrogel contracted from circumference to the interior, which retard the spreading of fibroblasts on the dynamic substrate and interrupted the initial attachment of the cell. However, contraction of collagen hydrogel had not only significant influence on the L929 cell proliferation, but also accelerated the apoptosis. Cell cycle analysis showed that contractile collagen hydrogel may promote cell cycle from G0/G1 phase to S phase, and DNA synthesis and cell proliferation were enhanced, but which may be different in contraction process. Therefore, as a scaffold for tissue engineering, the strategy for inhibition of the contraction of collagen hydrogel should be taken into account.

  19. Quantification of collagen distributions in rat hyaline and fibro cartilages based on second harmonic generation imaging

    Science.gov (United States)

    Zhu, Xiaoqin; Liao, Chenxi; Wang, Zhenyu; Zhuo, Shuangmu; Liu, Wenge; Chen, Jianxin

    2016-10-01

    Hyaline cartilage is a semitransparent tissue composed of proteoglycan and thicker type II collagen fibers, while fibro cartilage large bundles of type I collagen besides other territorial matrix and chondrocytes. It is reported that the meniscus (fibro cartilage) has a greater capacity to regenerate and close a wound compared to articular cartilage (hyaline cartilage). And fibro cartilage often replaces the type II collagen-rich hyaline following trauma, leading to scar tissue that is composed of rigid type I collagen. The visualization and quantification of the collagen fibrillar meshwork is important for understanding the role of fibril reorganization during the healing process and how different types of cartilage contribute to wound closure. In this study, second harmonic generation (SHG) microscope was applied to image the articular and meniscus cartilage, and textural analysis were developed to quantify the collagen distribution. High-resolution images were achieved based on the SHG signal from collagen within fresh specimens, and detailed observations of tissue morphology and microstructural distribution were obtained without shrinkage or distortion. Textural analysis of SHG images was performed to confirm that collagen in fibrocartilage showed significantly coarser compared to collagen in hyaline cartilage (p imaging degenerative tissues or assessing wound repair following cartilage injury.

  20. Progress of research on corneal collagen cross-linking for corneal melting

    Directory of Open Access Journals (Sweden)

    Ke-Ren Xiao

    2016-06-01

    Full Text Available Corneal collagen cross-linking(CXLcould increase the mechanical strength, biological stability and halt ectasia progression due to covalent bond formed by photochemical reaction between ultraviolet-A and emulsion of riboflavin between collagen fibers in corneal stroma. Corneal melting is an autoimmune related noninfectious corneal ulcer. The mechanism of corneal melting, major treatment, the basic fundamental of ultraviolet-A riboflavin induced CXL and the clinical researches status and experiment in CXL were summarized in the study.

  1. Study on Different Modification Methods of Collagen for Tissue Engineering

    Institute of Scientific and Technical Information of China (English)

    XU Xin-yu

    2008-01-01

    Because of the excellent biocompatibility and its specific amino sequences, collagen is an ideal biomedical material for tissue engineering applications. But collagen is usually lack of mechanical strength to form a rigid 3-D matrix and lack of ability to resist collagenase. In order to be a tissue engineering scaffold, collagen must strengthen its structures by modifying with chemical crosslinkers. Chemical crosslinkers used for modif-ying collagen fibers include glutaraldehyde (GA), epoxy compounds (PC) and carbodiim-ides (EDC). The aim of this study is to choose the best chemical crosslinker from the three reagents. In terms of the resistance to collagenase degradation, chemical cross-link-ing with PC provided the best protection; in terms of the mechanical characterization, chemical cross-linking with GA provided the best;and in terms of the biocompatibility, chemical cross-linking with EDC provided the best. There is not a reagent which has all merits for collagen crosslinking, so we should select the crosslinking reagent as the de-mands of use ask.

  2. Can green solvents be alternatives for thermal stabilization of collagen?

    Science.gov (United States)

    Mehta, Ami; Rao, J Raghava; Fathima, Nishter Nishad

    2014-08-01

    "Go Green" campaign is gaining light for various industrial applications where water consumption needs to be reduced. To resolve this, industries have adopted usage of green, organic solvents, as an alternative to water. For leather making, tanning industry consumes gallons of water. Therefore, for adopting green solvents in leather making, it is necessary to evaluate its influence on type I collagen, the major protein present in the skin matrix. The thermal stability of collagen from rat tail tendon fiber (RTT) treated with seven green solvents namely, ethanol, ethyl lactate, ethyl acetate, propylene carbonate, propylene glycol, polyethylene glycol-200 and heptane was determined using differential scanning calorimetry (DSC). Crosslinking efficiency of basic chromium sulfate and wattle on RTT in green solvents was determined. DSC thermograms show increase in thermal stability of RTT collagen against heat with green solvents (>78°C) compared to water (63°C). In the presence of crosslinkers, RTT demonstrated thermal stability >100°C in some green solvents, resulting in increased intermolecular forces between collagen, solvent and crosslinkers. The significant improvement in thermal stability of collagen potentiates the capability of green solvents as an alternative for water.

  3. A constitutive model of soft tissue: From nanoscale collagen to tissue continuum

    KAUST Repository

    Tang, Huang

    2009-04-08

    Soft collagenous tissue features many hierarchies of structure, starting from tropocollagen molecules that form fibrils, and proceeding to a bundle of fibrils that form fibers. Here we report the development of an atomistically informed continuum model of collagenous tissue. Results from full atomistic and molecular modeling are linked with a continuum theory of a fiber-reinforced composite, handshaking the fibril scale to the fiber and continuum scale in a hierarchical multi-scale simulation approach. Our model enables us to study the continuum-level response of the tissue as a function of cross-link density, making a link between nanoscale collagen features and material properties at larger tissue scales. The results illustrate a strong dependence of the continuum response as a function of nanoscopic structural features, providing evidence for the notion that the molecular basis for protein materials is important in defining their larger-scale mechanical properties. © 2009 Biomedical Engineering Society.

  4. Physics of soft hyaluronic acid-collagen type II double network gels

    Science.gov (United States)

    Morozova, Svetlana; Muthukumar, Murugappan

    2015-03-01

    Many biological hydrogels are made up of multiple interpenetrating, charged components. We study the swelling, elastic diffusion, mechanical, and optical behaviors of 100 mol% ionizable hyaluronic acid (HA) and collagen type II fiber networks. Dilute, 0.05-0.5 wt% hyaluronic acid networks are extremely sensitive to solution salt concentration, but are stable at pH above 2. When swelled in 0.1M NaCl, single-network hyaluronic acid gels follow scaling laws relevant to high salt semidilute solutions; the elastic shear modulus G' and diffusion constant D scale with the volume fraction ϕ as G' ~ϕ 9 / 4 and D ~ϕ 3 / 4 , respectively. With the addition of a collagen fiber network, we find that the hyaluronic acid network swells to suspend the rigid collagen fibers, providing extra strength to the hydrogel. Results on swelling equilibria, elasticity, and collective diffusion on these double network hydrogels will be presented.

  5. Anisotropic microsrheology of self-assembling collagen networks

    Science.gov (United States)

    Dutov, Pavel

    Collagen is the main component of human connective tissue and extracellular matrix. Here we report multiple novel methods for utilizing optical tweezers to measure mechanical properties of different hierarchical levels of collagenous materials. First, we introduce a method for optical trap calibration that is suitable for viscoelastic material. The method is designed for use on experimental setups with two optical tweezers and is based on pulling a trapped particle with one trap while holding it with the other. The method combines advantages of commonly known PSD-fitting and fast-sweeping methods, allowing calibration of a completely fixed trap in a fluid of unknown viscosity/viscoelasticity without additional expensive equipment. Then we report an approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. The approach also avoids the traditional drying-soaking cycle, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. Lastly, we report a new method for characterizing anisotropic viscoelastic response of collagenous matrices. Anisotropic collagenous extracellular matrices are used in biomedicine to enhance the wound healing process by directing fibroblast proliferation. We utilize an optical trap to monitor the thermal fluctuations of microspheres embedded into collagenous network to extract a viscoelastic response function of the network along the principal axes of anisotropy.

  6. Rheology and Confocal Reflectance Microscopy as Probes of Mechanical Properties and Structure during Collagen and Collagen/Hyaluronan Self-Assembly

    Science.gov (United States)

    Yang, Ya-li; Kaufman, Laura J.

    2009-01-01

    In this work, the gelation of three-dimensional collagen and collagen/hyaluronan (HA) composites is studied by time sweep rheology and time lapse confocal reflectance microscopy (CRM). To investigate the complementary nature of these techniques, first collagen gel formation is investigated at concentrations of 0.5, 1.0, and 1.5 mg/mL at 37°C and 32°C. The following parameters are used to describe the self-assembly process in all gels: the crossover time (tc), the slope of the growth phase (kg), and the arrest time (ta). The first two measures are determined by rheology, and the third by CRM. A frequency-independent rheological measure of gelation, tg, is also measured at 37°C. However, this quantity cannot be straightforwardly determined for gels formed at 32°C, indicating that percolation theory does not fully capture the dynamics of collagen network formation. The effects of collagen concentration and gelation temperature on kg, tc, and ta as well as on the mechanical properties and structure of these gels both during gelation and at equilibrium are elucidated. Composite collagen/HA gels are also prepared, and their properties are monitored at equilibrium and during gelation at 37°C and 32°C. We show that addition of HA subtly alters mechanical properties and structure of these systems both during the gelation process and at equilibrium. This occurs in a temperature-dependent manner, with the ratio of HA deposited on collagen fibers versus that distributed homogeneously between fibers increasing with decreasing gelation temperature. In addition to providing information on collagen and collagen/HA structure and mechanical properties during gelation, this work shows new ways in which rheology and microscopy can be used complementarily to reveal details of gelation processes. PMID:19217873

  7. Rheology and confocal reflectance microscopy as probes of mechanical properties and structure during collagen and collagen/hyaluronan self-assembly.

    Science.gov (United States)

    Yang, Ya-li; Kaufman, Laura J

    2009-02-18

    In this work, the gelation of three-dimensional collagen and collagen/hyaluronan (HA) composites is studied by time sweep rheology and time lapse confocal reflectance microscopy (CRM). To investigate the complementary nature of these techniques, first collagen gel formation is investigated at concentrations of 0.5, 1.0, and 1.5 mg/mL at 37 degrees C and 32 degrees C. The following parameters are used to describe the self-assembly process in all gels: the crossover time (t(c)), the slope of the growth phase (k(g)), and the arrest time (t(a)). The first two measures are determined by rheology, and the third by CRM. A frequency-independent rheological measure of gelation, t(g), is also measured at 37 degrees C. However, this quantity cannot be straightforwardly determined for gels formed at 32 degrees C, indicating that percolation theory does not fully capture the dynamics of collagen network formation. The effects of collagen concentration and gelation temperature on k(g), t(c), and t(a) as well as on the mechanical properties and structure of these gels both during gelation and at equilibrium are elucidated. Composite collagen/HA gels are also prepared, and their properties are monitored at equilibrium and during gelation at 37 degrees C and 32 degrees C. We show that addition of HA subtly alters mechanical properties and structure of these systems both during the gelation process and at equilibrium. This occurs in a temperature-dependent manner, with the ratio of HA deposited on collagen fibers versus that distributed homogeneously between fibers increasing with decreasing gelation temperature. In addition to providing information on collagen and collagen/HA structure and mechanical properties during gelation, this work shows new ways in which rheology and microscopy can be used complementarily to reveal details of gelation processes.

  8. Collagen-Immobilized Lipases Show Good Activity and Reusability for Butyl Butyrate Synthesis.

    Science.gov (United States)

    Dewei, Song; Min, Chen; Haiming, Cheng

    2016-11-01

    Candida rugosa lipases were immobilized onto collagen fibers through glutaraldehyde cross-linking method. The immobilization process has been optimized. Under the optimal immobilization conditions, the activity of the collagen-immobilized lipase reached 340 U/g. The activity was recovered of 28.3 % by immobilization. The operational stability of the obtained collagen-immobilized lipase for hydrolysis of olive oil emulsion was determined. The collagen-immobilized lipase showed good tolerance to temperature and pH variations in comparison to free lipase. The collagen-immobilized lipase was also applied as biocatalyst for synthesis of butyl butyrate from butyric acid and 1-butanol in n-hexane. The conversion yield was 94 % at the optimal conditions. Of its initial activity, 64 % was retained after 5 cycles for synthesizing butyl butyrate in n-hexane.

  9. uPARAP/endo180 directs lysosomal delivery and degradation of collagen IV

    DEFF Research Database (Denmark)

    Kjøller, Lars; Engelholm, Lars H; Høyer-Hansen, Maria

    2004-01-01

    transmembrane glycoprotein urokinase plasminogen activator receptor-associated protein (uPARAP/endo180) directs collagen IV for lysosomal delivery and degradation. In wild-type fibroblasts, fluorescently labeled collagen IV was first internalized into vesicular structures with diffuse fluorescence eventually...... appearing uniformly within the wild-type cells after longer incubation times. In these cells, some collagen-containing vesicles were identified as lysosomes by staining for LAMP-1. In contrast, collagen IV remained extracellular and associated with fiber-like structures on uPARAP/endo180-deficient...... fibroblasts. Blocking lysosomal cysteine proteases with the inhibitor E64d resulted in strong accumulation of collagen IV in lysosomes in wild-type cells, but only very weak intracellular fluorescence accumulation in uPARAP/endo180-deficient fibroblasts. We conclude that uPARAP/endo180 is critical...

  10. Monitoring the thermally induced structural transitions of collagen by use of second-harmonic generation microscopy

    Science.gov (United States)

    Lin, Sung-Jan; Hsiao, Chih-Yuan; Sun, Yen; Lo, Wen; Lin, Wei-Chou; Jan, Gwo-Jen; Jee, Shiou-Hwa; Dong, Chen-Yuan

    2005-03-01

    The thermal disruption of collagen I in rat tail tendon is investigated with second-harmonic generation (SHG) microscopy. We investigate its effects on SHG images and intensity in the temperature range 25°-60°C. We find that the SHG signal decreases rapidly starting at 45°C. However, SHG imaging reveals that breakage of collagen fibers is not evident until 57°C and worsens with increasing temperature. At 57°C, structures of both molten and fibrous collagen exist, and the disruption of collagen appears to be complete at 60°C. Our results suggest that, in addition to intensity measurement, SHG imaging is necessary for monitoring details of thermally induced changes in collagen structures in biomedical applications.

  11. Effect of ionic liquids on the different hierarchical order of type I collagen.

    Science.gov (United States)

    Mehta, Ami; Rao, J Raghava; Fathima, Nishter Nishad

    2014-05-01

    The effect of ionic liquids (ILs) on proteins has been gaining huge interest due to easy tunability of cation and anion for generating the desired effect. This study explores the effect of alkyl imidazolium chloride ILs on collagen at molecular, inter-fibrillar and skin matrix level. Circular dichroic studies reveal that at the molecular level, the secondary structure of collagen was not affected by imidazolium ILs and there was no change in thermal stability as well. However, collagen at the inter-fibrillar level behaved differently. With increase in concentration of ILs, remarkable decrease in thermal stability of rat tail tendon (RTT) collagen fibers with marginal swelling effect was seen. SEM micrographs of skin matrix treated with IL show opening up of pores. This kind of exquisite behavior of ILs at different hierarchal order of collagen indicates that ILs are endowed with potential lyotropic action, which can be judiciously employed for biomedical applications.

  12. uPARAP/endo180 directs lysosomal delivery and degradation of collagen IV

    DEFF Research Database (Denmark)

    Kjøller, Lars; Engelholm, Lars H; Høyer-Hansen, Maria

    2004-01-01

    transmembrane glycoprotein urokinase plasminogen activator receptor-associated protein (uPARAP/endo180) directs collagen IV for lysosomal delivery and degradation. In wild-type fibroblasts, fluorescently labeled collagen IV was first internalized into vesicular structures with diffuse fluorescence eventually......Collagen turnover is crucial for tissue homeostasis and remodeling and pathological processes such as cancer invasion, but the underlying molecular mechanisms are poorly understood. A major pathway appears to be internalization and degradation by fibroblasts. We now show that the endocytic...... appearing uniformly within the wild-type cells after longer incubation times. In these cells, some collagen-containing vesicles were identified as lysosomes by staining for LAMP-1. In contrast, collagen IV remained extracellular and associated with fiber-like structures on uPARAP/endo180-deficient...

  13. Polarization response of second-harmonic images for different collagen spatial distributions

    Science.gov (United States)

    Ávila, Francisco J.; del Barco, Oscar; Bueno, Juan M.

    2016-06-01

    The response to polarization of second-harmonic generation (SHG) microscopy images of samples with different collagen distributions (quasialigned, partially organized, and nonorganized) has been analyzed. A linear decay relationship between the external arrangement and polarization sensitivity was found. SHG signal from nonorganized samples presented a large structural dispersion and a weak dependence with incident polarization. Polarization dependence is also associated with the internal organization of the collagen fibers, directly related to the ratio of hyperpolarizabilities ρ. This parameter can experimentally be computed from the modulation of the SHG signal. The results show that both external and internal collagen structures are closely related. This provides a tool to obtain information of internal properties from the polarimetric response of the external spatial distribution of collagen, which might be useful in clinical diagnosis of pathologies related to changes in collagen structure.

  14. Collagen Conduit Versus Microsurgical Neurorrhaphy

    DEFF Research Database (Denmark)

    Boeckstyns, Michel; Sørensen, Allan Ibsen; Viñeta, Joaquin Fores

    2013-01-01

    To compare repair of acute lacerations of mixed sensory-motor nerves in humans using a collagen tube versus conventional repair.......To compare repair of acute lacerations of mixed sensory-motor nerves in humans using a collagen tube versus conventional repair....

  15. Collagen for bone tissue regeneration.

    Science.gov (United States)

    Ferreira, Ana Marina; Gentile, Piergiorgio; Chiono, Valeria; Ciardelli, Gianluca

    2012-09-01

    In the last decades, increased knowledge about the organization, structure and properties of collagen (particularly concerning interactions between cells and collagen-based materials) has inspired scientists and engineers to design innovative collagen-based biomaterials and to develop novel tissue-engineering products. The design of resorbable collagen-based medical implants requires understanding the tissue/organ anatomy and biological function as well as the role of collagen's physicochemical properties and structure in tissue/organ regeneration. Bone is a complex tissue that plays a critical role in diverse metabolic processes mediated by calcium delivery as well as in hematopoiesis whilst maintaining skeleton strength. A wide variety of collagen-based scaffolds have been proposed for different tissue engineering applications. These scaffolds are designed to promote a biological response, such as cell interaction, and to work as artificial biomimetic extracellular matrices that guide tissue regeneration. This paper critically reviews the current understanding of the complex hierarchical structure and properties of native collagen molecules, and describes the scientific challenge of manufacturing collagen-based materials with suitable properties and shapes for specific biomedical applications, with special emphasis on bone tissue engineering. The analysis of the state of the art in the field reveals the presence of innovative techniques for scaffold and material manufacturing that are currently opening the way to the preparation of biomimetic substrates that modulate cell interaction for improved substitution, restoration, retention or enhancement of bone tissue function.

  16. Engineering fibrin-based tissue constructs from myofibroblasts and application of constraints and strain to induce cell and collagen reorganization.

    Science.gov (United States)

    de Jonge, Nicky; Baaijens, Frank P T; Bouten, Carlijn V C

    2013-10-28

    Collagen content and organization in developing collagenous tissues can be influenced by local tissue strains and tissue constraint. Tissue engineers aim to use these principles to create tissues with predefined collagen architectures. A full understanding of the exact underlying processes of collagen remodeling to control the final tissue architecture, however, is lacking. In particular, little is known about the (re)orientation of collagen fibers in response to changes in tissue mechanical loading conditions. We developed an in vitro model system, consisting of biaxially-constrained myofibroblast-seeded fibrin constructs, to further elucidate collagen (re)orientation in response to i) reverting biaxial to uniaxial static loading conditions and ii) cyclic uniaxial loading of the biaxially-constrained constructs before and after a change in loading direction, with use of the Flexcell FX4000T loading device. Time-lapse confocal imaging is used to visualize collagen (re)orientation in a nondestructive manner. Cell and collagen organization in the constructs can be visualized in real-time, and an internal reference system allows us to relocate cells and collagen structures for time-lapse analysis. Various aspects of the model system can be adjusted, like cell source or use of healthy and diseased cells. Additives can be used to further elucidate mechanisms underlying collagen remodeling, by for example adding MMPs or blocking integrins. Shape and size of the construct can be easily adapted to specific needs, resulting in a highly tunable model system to study cell and collagen (re)organization.

  17. Characterization of Acid Soluble Collagen from Redbelly Yellowtail Fusilier Fish Skin (Caesio cuning

    Directory of Open Access Journals (Sweden)

    Ika Astiana

    2016-04-01

    Full Text Available Fish skin can be used as raw material for producing collagen. The collagen can be extracted by chemical or combination of chemical and enzymatic processes. Extraction of collagen chemically can do with the acid process that produces acid soluble collagen (ASC. This study aimed to determine the optimum concentration and time of pretreatment and extraction, also to determine the characteristics of the acid soluble collagen from the skin of yellow tail fish. Extraction of collagen done by pretreatment using NaOH at the concentration of 0.05; 0.1; and 0.15 M and extraction using acetic acid at the concentration of 0.3; 0.5; and 0.7 M. Pretreatment NaOH with concentration 0.05 M and soaking time of 8 hours is the best combination for eliminating non collagen protein. Combination treatment of acetic acid at the concentration of 0.3 M for 3 days obtained the best solubility. The yield of collagen ASC was 18.4±1.49% (db and 5.79±0.47% (wb. Amino acid composition that is dominant in the ASC collagen was glycine (25.09±0.003%, alanine (13.71±0.075%, and proline (12.15±0.132%. Collagen from yellow tail fish skin has α1, α2, β and γ protein structure with the molecular weight of 125, 113, 170-181, and 208 KDa. The transition and melting temperatures of collagen were 67.69oC and 144.4oC. The surface structure of collagen by analysis of SEM has fibers on the surface.

  18. Quantifying collagen orientation in breast tissue biopsies using SLIM (Conference Presentation)

    Science.gov (United States)

    Majeed, Hassaan; Okoro, Chukwuemeka; Balla, Andre; Toussaint, Kimani C.; Popescu, Gabriel

    2017-02-01

    Breast cancer is a major public health problem worldwide, being the most common type of cancer among women according to the World Health Organization (WHO). The WHO has further stressed the importance of an early determination of the disease course through prognostic markers. Recent studies have shown that the alignment of collagen fibers in tumor adjacent stroma correlate with poorer health outcomes in patients. Such studies have typically been carried out using Second-Harmonic Generation (SHG) microscopy. SHG images are very useful for quantifying collagen fiber orientation due their specificity to non-centrosymmetric structures in tissue, leading to high contrast in collagen rich areas. However, the imaging throughput in SHG microscopy is limited by its point scanning geometry. In this work, we show that SLIM, a wide-field high-throughput QPI technique, can be used to obtain the same information on collagen fiber orientation as is obtainable through SHG microscopy. We imaged a tissue microarray containing both benign and malignant cores using both SHG microscopy and SLIM. The cellular (non-collagenous) structures in the SLIM images were next segmented out using an algorithm developed in-house. Using the previously published Fourier Transform Second Harmonic Generation (FT-SHG) tool, the fiber orientations in SHG and segmented SLIM images were then quantified. The resulting histograms of fiber orientation angles showed that both SHG and SLIM generate similar measurements of collagen fiber orientation. The SLIM modality, however, can generate these results at much higher throughput due to its wide-field, whole-slide scanning capabilities.

  19. Engineering and Characterization of Collagen Networks Using Wet Atomic Force Microscopy and Environmental Scanning Electron Microscopy

    Science.gov (United States)

    Osborn, Jenna; Coffey, Tonya; Conrad, Brad; Burris, Jennifer; Hester, Brooke

    2014-03-01

    Collagen is an abundant protein and its monomers covalently crosslink to form fibrils which form fibers which contribute to forming macrostructures like tendon or bone. While the contribution is well understood at the macroscopic level, it is not well known at the fibril level. We wish to study the mechanical properties of collagen for networks of collagen fibers that vary in size and density. We present here a method to synthesize collagen networks from monomers and that allows us to vary the density of the networks. By using biotynilated collagen and a surface that is functionalized with avidin, we generate two-dimensional collagen networks across the surface of a silicon wafer. During network synthesis, the incubation time is varied from 30 minutes to 3 hours or temperature is varied from 25°C to 45°C. The two-dimensional collagen network created in the process is characterized using environmental atomic force microscopy (AFM) and scanning electron microscopy (SEM). The network density is measured by the number of strands in one frame using SPIP software. We expect that at body temperature (37°C) and with longer incubation times, the network density should increase.

  20. Guiding the orientation of smooth muscle cells on random and aligned polyurethane/collagen nanofibers.

    Science.gov (United States)

    Jia, Lin; Prabhakaran, Molamma P; Qin, Xiaohong; Ramakrishna, Seeram

    2014-09-01

    Fabricating scaffolds that can simulate the architecture and functionality of native extracellular matrix is a huge challenge in vascular tissue engineering. Various kinds of materials are engineered via nano-technological approaches to meet the current challenges in vascular tissue regeneration. During this study, nanofibers from pure polyurethane and hybrid polyurethane/collagen in two different morphologies (random and aligned) and in three different ratios of polyurethane:collagen (75:25; 50:50; 25:75) are fabricated by electrospinning. The fiber diameters of the nanofibrous scaffolds are in the range of 174-453 nm and 145-419 for random and aligned fibers, respectively, where they closely mimic the nanoscale dimensions of native extracellular matrix. The aligned polyurethane/collagen nanofibers expressed anisotropic wettability with mechanical properties which is suitable for regeneration of the artery. After 12 days of human aortic smooth muscle cells culture on different scaffolds, the proliferation of smooth muscle cells on hybrid polyurethane/collagen (3:1) nanofibers was 173% and 212% higher than on pure polyurethane scaffolds for random and aligned scaffolds, respectively. The results of cell morphology and protein staining showed that the aligned polyurethane/collagen (3:1) scaffold promote smooth muscle cells alignment through contact guidance, while the random polyurethane/collagen (3:1) also guided cell orientation most probably due to the inherent biochemical composition. Our studies demonstrate the potential of aligned and random polyurethane/collagen (3:1) as promising substrates for vascular tissue regeneration.

  1. Linear ordered collagen scaffolds loaded with collagen-binding neurotrophin-3 promote axonal regeneration and partial functional recovery after complete spinal cord transection.

    Science.gov (United States)

    Fan, Juan; Xiao, Zhifeng; Zhang, Hongtian; Chen, Bing; Tang, Guoqiang; Hou, Xianglin; Ding, Wenyong; Wang, Bin; Zhang, Peng; Dai, Jianwu; Xu, Ruxiang

    2010-09-01

    Neurotrophin-3 (NT3) is an important neurotrophic factor for spinal cord injury (SCI) repair. However, constant exchange of cerebrospinal fluid often decreases the effective dosage of NT3 at the targeted injury site. In the present study, a recombinant collagen-binding NT3 (CBD-NT3), consisting of a collagen-binding domain (CBD) and native NT3, was constructed. Linear rat-tail collagen (LRTC) was used as a physical carrier for CBD-NT3 to construct a LRTC/C3 system. The collagen-binding ability of CBD-NT3 was verified, and the bioactivity of CBD-NT3 was assayed with neurite outgrowth of dorsal root ganglia (DRG) explants and DRG cells in vitro. After complete spinal cord transection in rats, LRTC/CBD-NT3 or the LRTC/NT3 system was transplanted into the injury site. Hindlimb locomotion recovery was closely observed using the Basso-Beattie-Bresnahan (BBB) locomotor rating scale and the grid walk test. Significant improvement was observed in the LRTC/CBD-NT3 group. The results of regenerating nerve fiber and anterograde tracing of biotinylated dextran amine (BDA)-labeled corticospinal tract (CST) fibers demonstrated axonal regeneration of LRTC/CBD-NT3 in the injured spinal cord. Serotonin fiber regrowth also illustrated the effectiveness of LRTC/CBD-NT3. Thus, collagen-binding NT3 with LRTC may provide an effective method for treating SCI.

  2. Analysis and quantification of collagen organization with the structure tensor in second harmonic microscopy images of ocular tissues.

    Science.gov (United States)

    Ávila, Francisco J; Bueno, Juan M

    2015-11-20

    The important biological role of collagen-based tissues and the changes produced in the fiber distribution under particular situations (surgery, pathology, external damage, etc.) require tools for the analysis of the collagen organization that might potentially help in early diagnoses. Since collagen structures provide efficient second harmonic generation (SHG) signals, SHG microscopy has emerged as a powerful technique to visualize collagen fibers and qualitatively discriminate normal from abnormal tissues. Here we propose a quantitative method based on the structure tensor to quantify the different organization of collagen patterns in SHG images of ocular tissues. Results show that well-organized collagen distributions present a high degree of isotropy (DoI), a dominant orientation (PO), and a low structural dispersion (SD). On the other hand, the PO vanishes when the collagen tissue is not organized as a consequence of an increase in the SD and a decrease in the DoI. The proposed method is also able to discriminate partially organized samples. The combination of SHG microscopy and the structure tensor is a useful method to objectively classify collagen distributions. Clinical applications of this technique could help in the diagnosis and tracking of pathologies related to collagen disorders in connective tissue.

  3. Architecturally defined scaffolds from synthetic collagen and elastin analogues for the fabrication of bioengineered tissues

    Science.gov (United States)

    Caves, Jeffrey Morris

    The microstructure and mechanics of collagen and elastin protein fiber networks dictate the mechanical responses of all soft tissues and related organ systems. In this project, we endeavored to meet or exceed native tissue biomechanical properties through mimicry of these extracellular matrix components with synthetic collagen fiber and a recombinant elastin-like protein polymer. Significantly, this work led to the development of a framework for the design and fabrication of protein-based tissue substitutes with enhanced strength, resilience, anisotropy, and more. We began with the development of a spinning process for scalable production of synthetic collagen fiber. Fiber with an elliptical cross-section of 53 +/- 14 by 21 +/- 3 mum and an ultimate tensile strength of 90 +/- 19 MPa was continuously produced at 60 meters per hour from an ultrafiltered collagen solution. The starting collagen concentration, flowrate, and needle size could be adjusted to control fiber size. The fiber was characterized with mechanical analysis, micro-differential scanning calorimetry, transmission electron microscopy, second harmonic generation analysis, and subcutaneous murine implant. We subsequently describe the scalable, semi-automated fabrication of elastin-like protein sheets reinforced with synthetic collagen fibers that can be positioned in a precisely defined three-dimensional hierarchical pattern. Multilamellar, fiber-reinforced elastic protein sheets were constructed with controlled fiber orientation and volume fraction. Structures were analyzed with scanning electron microscopy, transmission electron microscopy, and digital volumetric imaging. The effect of fiber orientation and volume fraction on Young's Modulus, yield stress, ultimate tensile stress, strain-to-failure, and resilience was evaluated in uniaxial tension. Increased fiber volume fraction and alignment with applied deformation significantly increased Young's Modulus, resilience, and yield stress. Highly

  4. Collagenous Gastritis: A Rare Entity

    Directory of Open Access Journals (Sweden)

    Faten Limaiem

    2015-06-01

    Full Text Available Collagenous gastritis is a rare entity of unknown etiology characterized histologically by the presence of a thick subepithelial collagen band associated with an inflammatory infiltrate of gastric mucosa. A 40-year-old male presented with a history of chronic intermittent abdominal pain for about 6 months. Physical examination was unremarkable, and biological tests were within normal range. The patient underwent esophagogastroduodenoscopy and colonoscopy which showed a nodular mucosa of the stomach. Biopsies of the duodenum and colon were unremarkable. However, biopsies of the gastric fundus revealed a mild chronic gastritis characterized by lymphocytic and plasma cell infiltration of deep mucosa, without lymphoid follicle formation or active inflammation. No microorganisms were identified on routine hematoxylin and eosin or Giemsa-stained sections. Subepithelial collagen in the gastric biopsies was thickened and showed entrapped capillaries. Subepithelial collagen was highlighted by Masson's trichrome staining and was negative for amyloid by Congo Red. In the areas containing thickened collagen, there were no intraepithelial lymphocytes. The final pathological diagnosis was collagenous gastritis. Collagenous gastritis is an extremely rare disease, but it is important to recognize its characteristic endoscopic and pathologic findings to make a correct diagnosis. Specific therapy for this rare entity has not yet been established. [J Interdiscipl Histopathol 2015; 3(2.000: 68-70

  5. The composition of engineered cartilage at the time of implantation determines the likelihood of regenerating tissue with a normal collagen architecture.

    Science.gov (United States)

    Nagel, Thomas; Kelly, Daniel J

    2013-04-01

    The biomechanical functionality of articular cartilage is derived from both its biochemical composition and the architecture of the collagen network. Failure to replicate this normal Benninghoff architecture in regenerating articular cartilage may in turn predispose the tissue to failure. In this article, the influence of the maturity (or functionality) of a tissue-engineered construct at the time of implantation into a tibial chondral defect on the likelihood of recapitulating a normal Benninghoff architecture was investigated using a computational model featuring a collagen remodeling algorithm. Such a normal tissue architecture was predicted to form in the intact tibial plateau due to the interplay between the depth-dependent extracellular matrix properties, foremost swelling pressures, and external mechanical loading. In the presence of even small empty defects in the articular surface, the collagen architecture in the surrounding cartilage was predicted to deviate significantly from the native state, indicating a possible predisposition for osteoarthritic changes. These negative alterations were alleviated by the implantation of tissue-engineered cartilage, where a mature implant was predicted to result in the formation of a more native-like collagen architecture than immature implants. The results of this study highlight the importance of cartilage graft functionality to maintain and/or re-establish joint function and suggest that engineering a tissue with a native depth-dependent composition may facilitate the establishment of a normal Benninghoff collagen architecture after implantation into load-bearing defects.

  6. Electrostatic effects in collagen fibrillization

    Science.gov (United States)

    Morozova, Svetlana; Muthukumar, Murugappan

    2014-03-01

    Using light scattering and AFM techniques, we have measured the kinetics of fibrillization of collagen (pertinent to the vitreous of human eye) as a function of pH and ionic strength. At higher and lower pH, collagen triple-peptides remain stable in solution without fibrillization. At neutral pH, the fibrillization occurs and its growth kinetics is slowed upon either an increase in ionic strength or a decrease in temperature. We present a model, based on polymer crystallization theory, to describe the observed electrostatic nature of collagen assembly.

  7. Sterile Keratitis following Collagen Crosslinking

    Science.gov (United States)

    Javadi, Mohammad-Ali; Feizi, Sepehr

    2014-01-01

    Purpose: To report a keratoconic eye that developed severe sterile keratitis and corneal scar after collagen crosslinking necessitating corneal transplantation. Case Report: A 26-year-old man with progressive keratoconus underwent collagen crosslinking and presented with severe keratitis 72 hours after the procedure. The initial impression was infectious corneal ulcer and a fortified antibiotic regimen was administered. However, the clinical course and confocal microscopy results prompted a diagnosis of sterile keratitis. The eye developed severe corneal scars leading to reduced visual acuity and necessitating corneal transplantation. Conclusion: Sterile keratitis may develop after collagen crosslinking resulting in profound visual loss leading to corneal transplantation. PMID:25709779

  8. Stability of collagen during denaturation.

    Science.gov (United States)

    Penkova, R; Goshev, I; Gorinstein, S; Nedkov, P

    1999-05-01

    The stability of calf skin collagen (CSC) type I during thermal and chemical denaturation in the presence of glycerol was investigated. Thermal denaturation of type I collagen was performed in the presence of glycerol or in combination with urea and sodium chloride. The denaturation curves obtained in the presence of urea or sodium chloride retained their original shape without glycerol. These curves were shifted upward proportionally to the glycerol concentration in the reaction medium. This means that glycerol and the denaturants act independently. The explanation is based on the difference in the mechanism of their action on the collagen molecule.

  9. Collagen-carbon nanotube composite materials as scaffolds in tissue engineering.

    Science.gov (United States)

    MacDonald, Rebecca A; Laurenzi, Brendan F; Viswanathan, Gunaranjan; Ajayan, Pulickel M; Stegemann, Jan P

    2005-09-01

    Carbon nanotubes (CNT) are attractive for use in fiber-reinforced composite materials due to their very high aspect ratio, combined with outstanding mechanical and electrical properties. Composite materials comprising a collagen matrix with embedded CNT were prepared by mixing solubilized Type I collagen with solutions of carboxylated single-walled carbon nanotubes (SWNT) at concentrations of 0, 0.2, 0.4, 0.8, and 2.0 weight percent. Living smooth muscle cells were incorporated at the time of collagen gelation to produce cell-seeded collagen-CNT composite matrices. Constructs containing 2.0 wt % CNT exhibited delayed gel compaction, relative to lower concentrations that compacted at the same rate as pure collagen controls. Cell viability in all constructs was consistently above 85% at both Day 3 and Day 7, whereas cell number in CNT-containing constructs was lower than in control constructs at Day 3, though statistically unchanged by Day 7. Scanning electron microscopy showed physical interactions between CNT and collagen matrix. Raman spectroscopy confirmed the presence of CNT at the expected diameter (0.85-1.30 nm), but did not indicate strong molecular interactions between the collagen and CNT components. Such collagen-CNT composite matrices may have utility as scaffolds in tissue engineering, or as components of biosensors or other medical devices.

  10. Fiber diffraction without fibers.

    Science.gov (United States)

    Poon, H-C; Schwander, P; Uddin, M; Saldin, D K

    2013-06-28

    Postprocessing of diffraction patterns of completely randomly oriented helical particles, as measured, for example, in so-called "diffract-and-destroy" experiments with an x-ray free electron laser can yield "fiber diffraction" patterns expected of fibrous bundles of the particles. This will allow "single-axis alignment" to be performed computationally, thus obviating the need to do this by experimental means such as forming fibers and laser or flow alignment. The structure of such particles may then be found by either iterative phasing methods or standard methods of fiber diffraction.

  11. Collagen type I Density on dental pulp inflamation of sprague-dawley rats following the application of trigona sp propolis from south sulawesi province,Indonesia

    OpenAIRE

    Ardo Sabir, Dr.drg. M.Kes

    2015-01-01

    The Result show That there is no significants difference of the collagen fibers density among 4 time periods of each group and among 5 groups of each time periods. The aim was to analyse the collagen type I density as the result of trigona sp propolis application in the dental pulp inflamation of sprague-dawley rats.

  12. Imaging collagen orientation using polarization-modulated second harmonic generation

    Science.gov (United States)

    Stoller, Patrick C.; Celliers, Peter M.; Reiser, Karen M.; Rubenchik, Alexander M.

    2002-06-01

    We use polarization-modulated second harmonic generation to image fiber orientation in collagen tissues, with an axial resolution of about 10 micrometers and a transverse resolution of up to 1 micrometers . A linearly polarized ultra-short pulse (200 fs) Ti:Sapphire laser beam is modulated using an electro-optic modulator and quarter-wave plate combination and focused onto a translation stage mounted sample using a microscope objective. The generated second harmonic light is collected using a photomultiplier tube and demodulated using phase sensitive detection to obtain signal intensity and fiber orientation information. In order to obtain second harmonic generation images of different types of collagen organization, we analyze several different tissues, including rat-tail tendon, mouse aorta, mouse fibrotic liver, and porcine skin. We can use our technique to image fibrotic tissue in histological sections of damaged liver and to identify burned tissue in porcine skin to a depth of a few hundred microns. Polarization-modulated second harmonic generation potentially could be a useful clinical technique for diagnosing collagen related disease or damage, especially in the skin.

  13. Imaging Collagen Orientation Using Polarization-Modulated Second Harmonic Generation

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, P; Celliers, P M; Reiser, K M; Rubenchik, A M

    2002-01-10

    We use polarization-modulated second harmonic generation to image fiber orientation in collagen tissues, with an axial resolution of about 10 {micro}m and a transverse resolution of up to 1 {micro}m. A linearly polarized ultra-short pulse (200 fs) Ti:Sapphire laser beam is modulated using an electro-optic modulator and quarter-wave plate combination and focused onto a translation stage mounted sample using a microscope objective. The generated second harmonic light is collected using a photomultiplier tube and demodulated using phase sensitive detection to obtain signal intensity and fiber orientation information. In order to obtain second harmonic generation images of different types of collagen organization, we analyze several different tissues, including rat-tail tendon, mouse aorta, mouse fibrotic liver, and porcine skin. We can use our technique to image fibrotic tissue in histological sections of damaged liver and to identify burned tissue in porcine skin to a depth of a few hundred microns. Polarization-modulated second harmonic generation potentially could be a useful clinical technique for diagnosing collagen related disease or damage, especially in the skin.

  14. Human collagen produced in plants

    Science.gov (United States)

    Shoseyov, Oded; Posen, Yehudit; Grynspan, Frida

    2014-01-01

    Consequential to its essential role as a mechanical support and affinity regulator in extracellular matrices, collagen constitutes a highly sought after scaffolding material for regeneration and healing applications. However, substantiated concerns have been raised with regard to quality and safety of animal tissue-extracted collagen, particularly in relation to its immunogenicity, risk of disease transmission and overall quality and consistency. In parallel, contamination with undesirable cellular factors can significantly impair its bioactivity, vis-a-vis its impact on cell recruitment, proliferation and differentiation. High-scale production of recombinant human collagen Type I (rhCOL1) in the tobacco plant provides a source of an homogenic, heterotrimeric, thermally stable “virgin” collagen which self assembles to fine homogenous fibrils displaying intact binding sites and has been applied to form numerous functional scaffolds for tissue engineering and regenerative medicine. In addition, rhCOL1 can form liquid crystal structures, yielding a well-organized and mechanically strong membrane, two properties indispensable to extracellular matrix (ECM) mimicry. Overall, the shortcomings of animal- and cadaver-derived collagens arising from their source diversity and recycled nature are fully overcome in the plant setting, constituting a collagen source ideal for tissue engineering and regenerative medicine applications. PMID:23941988

  15. Modern Collagen Wound Dressings: Function and Purpose

    OpenAIRE

    Fleck, Cynthia Ann; Simman, Richard

    2011-01-01

    Collagen, which is produced by fibroblasts, is the most abundant protein in the human body. A natural structural protein, collagen is involved in all 3 phases of the wound-healing cascade. It stimulates cellular migration and contributes to new tissue development. Because of their chemotactic properties on wound fibroblasts, collagen dressings encourage the deposition and organization of newly formed collagen, creating an environment that fosters healing. Collagen-based biomaterials stimulate...

  16. Modern Collagen Wound Dressings: Function and Purpose

    OpenAIRE

    Fleck, Cynthia Ann; Simman, Richard

    2011-01-01

    Collagen, which is produced by fibroblasts, is the most abundant protein in the human body. A natural structural protein, collagen is involved in all 3 phases of the wound-healing cascade. It stimulates cellular migration and contributes to new tissue development. Because of their chemotactic properties on wound fibroblasts, collagen dressings encourage the deposition and organization of newly formed collagen, creating an environment that fosters healing. Collagen-based biomaterials stimulate...

  17. Quantitative characterization of developing collagen gels using optical coherence tomography

    Science.gov (United States)

    Levitz, David; Hinds, Monica T.; Choudhury, Niloy; Tran, Noi T.; Hanson, Stephen R.; Jacques, Steven L.

    2010-03-01

    Nondestructive optical imaging methods such as optical coherence tomography (OCT) have been proposed for characterizing engineered tissues such as collagen gels. In our study, OCT was used to image collagen gels with different seeding densities of smooth muscle cells (SMCs), including acellular gels, over a five-day period during which the gels contracted and became turbid with increased optical scattering. The gels were characterized quantitatively by their optical properties, specified by analysis of OCT data using a theoretical model. At 6 h, seeded cell density and scattering coefficient (μs) were correlated, with μs equal to 10.8 cm-1/(106 cells/mL). Seeded cell density and the scattering anisotropy (g) were uncorrelated. Over five days, the reflectivity in SMC gels gradually doubled with little change in optical attenuation, which indicated a decrease in g that increased backscatter, but only a small drop in μs. At five days, a subpopulation of sites on the gel showed substantially higher reflectivity (approximately a tenfold increase from the first 24 h). In summary, the increased turbidity of SMC gels that develops over time is due to a change in the structure of collagen, which affects g, and not simply due to a change in number density of collagen fibers due to contraction.

  18. Hydration dynamics of the collagen triple helix by NMR.

    Science.gov (United States)

    Melacini, G; Bonvin, A M; Goodman, M; Boelens, R; Kaptein, R

    2000-07-28

    The hydration of the collagen-like Ac-(Gly-Pro-Hyp)(6)-NH(2) triple-helical peptide in solution was investigated using an integrated set of high-resolution NMR hydration experiments, including different recently developed exchange-network editing methods. This approach was designed to explore the hydration dynamics in the proximity of labile groups, such as the hydroxyproline hydroxyl group, and revealed that the first shell of hydration in collagen-like triple helices is kinetically labile with upper limits for water molecule residence times in the nanosecond to sub-nanosecond range. This result is consistent with a "hopping" hydration model in which solvent molecules are exchanged in and out of solvation sites at a rate that is not directly correlated to the degree of site localization. The hopping model thus reconciles the dynamic view of hydration revealed by NMR with the previously suggested partially ordered semi-clathrate-like cylinder of hydration. In addition, the nanosecond to sub-nanosecond upper limits for water molecule residence times imply that hydration-dehydration events are not likely to be the rate-limiting step for triple helix self-recognition, complementing previous investigations on water dynamics in collagen fibers. This study has also revealed labile proton features expected to facilitate the characterization of the structure and folding of triple helices in collagen peptides.

  19. Regulation of migratory activity of human keratinocytes by topography of multiscale collagen-containing nanofibrous matrices.

    Science.gov (United States)

    Fu, Xiaoling; Xu, Meng; Liu, Jie; Qi, Yanmei; Li, Shaohua; Wang, Hongjun

    2014-02-01

    Nanofibrous matrices hold great promise in skin wound repair partially due to their capability of recapturing the essential attributes of native extracellular matrix (ECM). With regard to limited studies on the effect of nanofibrous matrices on keratinocytes, the present study was aimed to understand how the topographical feature of nanofibrous matrices regulates keratinocyte motility by culturing keratinocytes on polycaprolactone (PCL)/collagen nanofibrous matrices (rough surface with fiber diameters of 331 ± 112 nm) or the matrices coated with a thin layer of collagen gel to form a secondary ultrafine fibrous network (smooth surface with ultrafine fiber diameters of 55 ± 26 nm). It was found that the PCL/collagen nanofibrous matrices alone did not stimulate cell migration, while collagen gel coating could significantly increase cell motility. Further studies demonstrated that the ultrafine fibrous network of collagen gel coating significantly activated integrin β1, Rac1 and Cdc42, facilitated the deposition of laminin-332 (formerly called laminin-5), and promoted the expression of active matrix metalloproteinases (MMPs) (i.e., MMP-2 and 9). Neutralization of integrin β1 activity abrogated the gel coating-induced keratinocyte migration. These findings provide important evidence on the role of topographical features of nanofibrous matrices in regulating the phenotypic alteration of keratinocytes and suggest the possible utility of collagen-containing nanofibrous matrices for skin regeneration especially in re-epithelialization.

  20. Optimal dehydrothermal processing conditions to improve biocompatibility and durability of a weakly denatured collagen scaffold.

    Science.gov (United States)

    Nakada, Akira; Shigeno, Keiji; Sato, Toshihiko; Hatayama, Takahide; Wakatsuki, Mariko; Nakamura, Tatsuo

    2016-08-03

    Collagen scaffolds are essential for tissue regeneration; however, preprocessing of these scaffolds is necessary because of their poor mechanical properties. The aim of this study was to determine the optimal condition for preparing a collagen scaffold with biocompatibility and durability. An atelocollagen fiber suspension was made and stored at -10°C in a container that could be cooled from the bottom to provide an orientation perpendicular to the collagen fiber and facilitate cell infiltration into the scaffold. After freeze-drying the frozen suspension, various collagen scaffolds were made by dehydrothermal (DHT) treatment under different conditions (processing temperature: 120-160°C for 0-28 h). Sections of the obtained materials were embedded under the back skin of rats, and the thickness and biocompatibility of the residual scaffold were evaluated after 2 weeks. The number of foreign body giant cells was counted to evaluate biocompatibility. Although the residual scaffold was thick, excessive DHT treatment caused a strong foreign body reaction. Weak DHT treatment resulted in a collagen scaffold with good biocompatibility but with reduced thickness. Overall, these results showed the restricted optimal conditions to make a collagen scaffold with good biocompatibility and ability to maintain sufficient space for tissue regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  1. Evaluation of epigallocatechin-3-gallate (EGCG) cross-linked collagen membranes and concerns on osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Chenyu; Deng, Jia [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Xiang, Lin; Wu, Yingying [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Wei, Xiawei [State Key Laboratory of Biotherapy and Laboratory for Aging Research, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 (China); Qu, Yili [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Man, Yi, E-mail: manyi780203@126.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)

    2016-10-01

    Collagen membranes have ideal biological and mechanical properties for supporting infiltration and proliferation of osteoblasts and play a vital role in guided bone regeneration (GBR). However, pure collagen can lead to inflammation, resulting in progressive bone resorption. Therefore, a method for regulating the level of inflammatory cytokines at surgical sites is paramount for the healing process. Epigallocatechin-3-gallate (EGCG) is a component extracted from green tea with numerous biological activities including an anti-inflammatory effect. Herein, we present a novel cross-linked collagen membrane containing different concentrations of EGCG (0.0064%, 0.064%, and 0.64%) to regulate the level of inflammatory factors secreted by pre-osteoblast cells; improve cell proliferation; and increase the tensile strength, wettability, and thermal stability of collagen membranes. Scanning electron microscope images show that the surfaces of collagen membranes became smoother and the collagen fiber diameters became larger with EGCG treatment. Measurement of the water contact angle demonstrated that introducing EGCG improved membrane wettability. Fourier transform infrared spectroscopy analyses indicated that the backbone of collagen was intact, and the thermal stability was significant improved in differential scanning calorimetry. The mechanical properties of 0.064% and 0.64% EGCG-treated collagen membranes were 1.5-fold greater than those of the control. The extent of cross-linking was significantly increased, as determined by a 2,4,6-trinitrobenzenesulfonic acid solution assay. The Cell Counting Kit-8 (CCK-8) and live/dead assays revealed that collagen membrane cross-linked by 0.0064% EGCG induced greater cell proliferation than pure collagen membranes. Additionally, real-time polymerase chain reaction and enzyme-linked immunosorbent assay results showed that EGCG significantly affected the production of inflammatory factors secreted by MC3T3-E1 cells. Taken together, our

  2. Characterization of fibrillar collagens and extracellular matrix of glandular benign prostatic hyperplasia nodules.

    Directory of Open Access Journals (Sweden)

    Tyler M Bauman

    Full Text Available Recent studies have associated lower urinary tract symptoms (LUTS in men with prostatic fibrosis, but a definitive link between collagen deposition and LUTS has yet to be demonstrated. The objective of this study was to evaluate ECM and collagen content within normal glandular prostate tissue and glandular BPH, and to evaluate the association of clinical parameters of LUTS with collagen content.Fibrillar collagen and ECM content was assessed in normal prostate (48 patients and glandular BPH nodules (24 patients using Masson's trichrome stain and Picrosirius red stain. Second harmonic generation (SHG imaging was used to evaluate collagen content. Additional BPH tissues (n = 47 were stained with Picrosirius red and the association between clinical parameters of BPH/LUTS and collagen content was assessed.ECM was similar in normal prostate and BPH (p = 0.44. Total collagen content between normal prostate and glandular BPH was similar (p = 0.27, but a significant increase in thicker collagen bundles was observed in BPH (p = 0.045. Using SHG imaging, collagen content in BPH (mean intensity = 62.52; SEM = 2.74 was significantly higher than in normal prostate (51.77±3.49; p = 0.02. Total collagen content was not associated with treatment with finasteride (p = 0.47 or α-blockers (p = 0.52, pre-TURP AUA symptom index (p = 0.90, prostate-specific antigen (p = 0.86, post-void residual (PVR; p = 0.32, prostate size (p = 0.21, or post-TURP PVR (p = 0.51. Collagen content was not associated with patient age in patients with BPH, however as men aged normal prostatic tissue had a decreased proportion of thick collagen bundles.The proportion of larger bundles of collagen, but not total collagen, is increased in BPH nodules, suggesting that these large fibers may play a role in BPH/LUTS. Total collagen content is independent of clinical parameters of BPH and LUTS. If fibrosis and overall ECM deposition are

  3. Composition and adaptation of human myotendinous junction and neighboring muscle fibers to heavy resistance training

    DEFF Research Database (Denmark)

    Jakobsen, J R; Mackey, A L; Knudsen, A B

    2016-01-01

    The myotendinous junction (MTJ) is a common site of strain injury and yet understanding of its composition and ability to adapt to loading is poor. The main aims of this study were to determine the profile of selected collagens and macrophage density in human MTJ and adjoining muscle fibers...... and were sectioned and stained immunohistochemically for collagen types I, III, VI, XII, XIV, XXII, Tenascin-C and CD68. Macrophage density and distribution was evaluated and the amount of each collagen type in muscle and MTJ was graded. Collagen XXII was observed solely at the MTJ, while all other...... collagens were abundant at the MTJ and in muscle perimysium or endomysium. The endomysial content of collagen XIV, macrophages and Tenascin-C increased following 4 weeks of training. These findings illustrate the heterogeneity of collagen type composition of human MTJ. The increase in collagen XIV following...

  4. Extraction and characterization of highly purified collagen from bovine pericardium for potential bioengineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maria Helena, E-mail: mariahelena.santos@gmail.com [Department of Dentistry, Federal University of Vales do Jequitinhonha e Mucuri-UFVJM, Diamantina/MG 39100-000 (Brazil); Center for Assessment and Development of Biomaterials-BioMat, Federal University of Vales do Jequitinhonha e Mucuri-UFVJM, Diamantina/MG 39100-000 (Brazil); Silva, Rafael M.; Dumont, Vitor C. [Department of Dentistry, Federal University of Vales do Jequitinhonha e Mucuri-UFVJM, Diamantina/MG 39100-000 (Brazil); Center for Assessment and Development of Biomaterials-BioMat, Federal University of Vales do Jequitinhonha e Mucuri-UFVJM, Diamantina/MG 39100-000 (Brazil); Neves, Juliana S. [Center for Assessment and Development of Biomaterials-BioMat, Federal University of Vales do Jequitinhonha e Mucuri-UFVJM, Diamantina/MG 39100-000 (Brazil); Mansur, Herman S. [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais-UFMG, Belo Horizonte/MG 31270-901 (Brazil); Heneine, Luiz Guilherme D. [Department of Health Science, Ezequiel Dias Foundation-FUNED, Belo Horizonte/MG 30510-010 (Brazil)

    2013-03-01

    Bovine pericardium is widely used as a raw material in bioengineering as a source of collagen, a fundamental structural molecule. The physical, chemical, and biocompatibility characteristics of these natural fibers enable their broad use in several areas of the health sciences. For these applications, it is important to obtain collagen of the highest possible purity. The lack of a method to produce these pure biocompatible materials using simple and economically feasible techniques presents a major challenge to their production on an industrial scale. This study aimed to extract, purify, and characterize the type I collagen protein originating from bovine pericardium, considered to be an abundant tissue resource. The pericardium tissue was collected from male animals at slaughter age. Pieces of bovine pericardium were enzymatically digested, followed by a novel protocol developed for protein purification using ion-exchange chromatography. The material was extensively characterized by electrophoresis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and infrared spectroscopy. The results showed a purified material with morphological properties and chemical functionalities compatible with type I collagen and similar to a highly purified commercial collagen. Thus, an innovative and relatively simple processing method was developed to extract and purify type I collagen from bovine tissue with potential applications as a biomaterial for regenerative tissue engineering. - Highlights: Black-Right-Pointing-Pointer Type I collagen was obtained from bovine pericardium, an abundant tissue resource. Black-Right-Pointing-Pointer A simple and feasible processing technique was developed to purify bovine collagen. Black-Right-Pointing-Pointer The appropriate process may be performed on industrial scale. Black-Right-Pointing-Pointer The pure collagen presented appropriate morphological and molecular characteristics. Black-Right-Pointing-Pointer The purify

  5. A micro-anatomical model of the distribution of myocardial endomysial collagen.

    Science.gov (United States)

    Macchiarelli, G; Ohtani, O; Nottola, S A; Stallone, T; Camboni, A; Prado, I M; Motta, P M

    2002-01-01

    Myocardial connective tissue probably provides passive support for regulating heart tensile strength and stiffness and ultimately for controlling heart mechanics through its endomysial part. However, endomysial collagen micro-arrangement is still a matter of debate. In order to define the fine distribution of left ventricle endomysial collagen, we applied the NaOH-scanning electron microscopy (SEM) maceration method (one of the techniques of choice for studying collagen micro-arrangement) to rabbit heart. Gomori-reticulum staining was used for correlated light microscopy (LM) observations. The SEM-NaOH method allowed isolation of collagen by removing other extracellular matrix components and cells and preserved collagen structure and position. Endomysial collagen appeared arranged in laminae that delimited the lacunae that were left empty by macerated myocytes and small vessels (mostly capillaries). These laminae were formed by reticular fibers, as confirmed by LM observations of Gomorireticulum-stained samples, and were organized in irregularly meshed networks made of thin (single) and thick (composed) filaments. In longitudinal views, collagen laminae extended the entire length of lacunae. In transversal views, the cut surface of the laminae appeared to be made of collagen bundles. These observations provide an updated microanatomical view of endomysial collagen distribution, which integrates previous studies. This model is based on the evidence that collagen laminae enveloped the surface of small vessels and myocytes. Thus, a type of myocyte-myocyte or capillary-myocyte "laminar connection" anchored to the entire cell length here is emphasized, rather than a type of "strut connection" anchored to defined loci, as usually described. This structure explains better how endomysium may provide the necessary support for heart compliance and protection against overstretch.

  6. A 3D Electroactive Polypyrrole-Collagen Fibrous Scaffold for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Kam W. Leong

    2011-02-01

    Full Text Available Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal or muscular cells. Here we report on the fabrication of polypyrrole-incorporated collagen-based fibers via interfacial polyelectrolyte complexation (IPC. The mean ultimate tensile strength of the fibers is 304.0 ± 61.0 MPa and the Young’s Modulus is 10.4 ± 4.3 GPa. Human bone marrow-derived mesenchymal stem cells (hMSCs are cultured on the fibers in a proliferating medium and stimulated with an external electrical pulse generator for 5 and 10 days. The effects of polypyrrole in the fiber system can be observed, with hMSCs adopting a neuronal-like morphology at day 10, and through the upregulation of neural markers, such as noggin, MAP2, neurofilament, β tubulin III and nestin. This study demonstrates the potential of this fiber system as an attractive 3D scaffold for tissue engineering, where collagen is present on the fiber surface for cellular adhesion, and polypyrrole is encapsulated within the fiber for enhanced electrical communication in cell-substrate and cell-cell interactions.

  7. Carbodiimide crosslinked collagen from porcine dermal matrix for high-strength tissue engineering scaffold.

    Science.gov (United States)

    Li, Jianhua; Ren, Na; Qiu, Jichuan; Jiang, Huaidong; Zhao, Hongshi; Wang, Guancong; Boughton, Robert I; Wang, Yingjun; Liu, Hong

    2013-10-01

    Naturally-derived collagens for tissue engineering are limited by low mechanical strength and rapid degradation. In this study, carbodiimide is used to chemically modify the collagen derived from porcine acellular dermal matrix (PADM). The results show that the strength and resistance of PADM to enzymatic digestion can be adjusted by the reconnection of free amino and carboxyl groups of the collagen fibers. The cytocompatibility of the crosslinked PADM was evaluated by cell adhesion and proliferation assays. The cell culture studies on crosslinked and uncrosslinked PADM showed that the modification does not affect the scaffold's biocompatibility. These results demonstrate that the PADM collagen materials can be strengthened through a low-cost, non-toxic crosslinking method for potential use in biomedical applications.

  8. SU-E-J-107: Supervised Learning Model of Aligned Collagen for Human Breast Carcinoma Prognosis

    Energy Technology Data Exchange (ETDEWEB)

    Bredfeldt, J; Liu, Y; Conklin, M; Keely, P; Eliceiri, K; Mackie, T [University of Wisconsin, Madison, WI (United States)

    2014-06-01

    Purpose: Our goal is to develop and apply a set of optical and computational tools to enable large-scale investigations of the interaction between collagen and tumor cells. Methods: We have built a novel imaging system for automating the capture of whole-slide second harmonic generation (SHG) images of collagen in registry with bright field (BF) images of hematoxylin and eosin stained tissue. To analyze our images, we have integrated a suite of supervised learning tools that semi-automatically model and score collagen interactions with tumor cells via a variety of metrics, a method we call Electronic Tumor Associated Collagen Signatures (eTACS). This group of tools first segments regions of epithelial cells and collagen fibers from BF and SHG images respectively. We then associate fibers with groups of epithelial cells and finally compute features based on the angle of interaction and density of the collagen surrounding the epithelial cell clusters. These features are then processed with a support vector machine to separate cancer patients into high and low risk groups. Results: We validated our model by showing that eTACS produces classifications that have statistically significant correlation with manual classifications. In addition, our system generated classification scores that accurately predicted breast cancer patient survival in a cohort of 196 patients. Feature rank analysis revealed that TACS positive fibers are more well aligned with each other, generally lower density, and terminate within or near groups of epithelial cells. Conclusion: We are working to apply our model to predict survival in larger cohorts of breast cancer patients with a diversity of breast cancer types, predict response to treatments such as COX2 inhibitors, and to study collagen architecture changes in other cancer types. In the future, our system may be used to provide metastatic potential information to cancer patients to augment existing clinical assays.

  9. Fiber biology

    Science.gov (United States)

    Cotton fiber cells arising from seed epidermis is the most important agricultural textile commodity in the world. To produce fully mature fibers, approximately two months of fiber developmental process are required. The timing of four distinctive fiber development stages consisting of initiation, ...

  10. External vibration enhances macromolecular crowding for construction of aligned three-dimensional collagen fibril scaffolds.

    Science.gov (United States)

    Hsu, Hsiao-Ting; Rau, Lih-Rou; Zeng, Yao-Nan; Kang, Yi-Lin; Tsai, Shiao-Wen; Wu, Min-Hsien

    2015-04-17

    There are many techniques for preparing two-dimensional aligned fibril matrices. However, the critical problem associated with these techniques is the destruction of the native structure (e.g., the α-helix) of the proteins. Moreover, most of these techniques cannot create a three-dimensional (3D), aligned reconstituted collagen fibril matrix in one step. In this study, we used a simple device composed of a pneumatic membrane that generates a tunable vibration frequency to apply physical stimulation to fabricate a 3D, aligned collagen fibril matrix with the characteristic D-period structure of collagen in one step. Using second harmonic images, we demonstrated that the aligned, reconstituted collagen fibrils preserve the native collagen D-period structure. The average angular deviation of fibril alignment was reduced to 25.01 ± 4.2° compared with the 39.7 ± 2.19° of alignment observed for the randomly distributed fibril matrix. In addition, the ultimate tensile strength of the aligned matrix when force was applied in the direction parallel to the fiber orientation was higher than that of the randomly oriented matrix. The aligned reconstituted collagen fibril matrix also enhanced the expression of smoothelin (a specific marker of contractile phenotype) of thoracic aortic smooth muscle cell (A7r5) relative to the randomly distributed collagen fibril matrix.

  11. Structural Basis for Platelet Collagen Responses by the Immune-type Receptor Glycoprotein VI

    Energy Technology Data Exchange (ETDEWEB)

    Horii,K.; Kahn, M.; Herr, A.

    2006-01-01

    Activation of circulating platelets by exposed vessel wall collagen is a primary step in the pathogenesis of heart attack and stroke, and drugs to block platelet activation have successfully reduced cardiovascular morbidity and mortality. In humans and mice, collagen activation of platelets is mediated by glycoprotein VI (GPVI), a receptor that is homologous to immune receptors but bears little sequence similarity to known matrix protein adhesion receptors. Here we present the crystal structure of the collagen-binding domain of human GPVI and characterize its interaction with a collagen-related peptide. Like related immune receptors, GPVI contains 2 immunoglobulin-like domains arranged in a perpendicular orientation. Significantly, GPVI forms a back-to-back dimer in the crystal, an arrangement that could explain data previously obtained from cell-surface GPVI inhibition studies. Docking algorithms identify 2 parallel grooves on the GPVI dimer surface as collagen-binding sites, and the orientation and spacing of these grooves precisely match the dimensions of an intact collagen fiber. These findings provide a structural basis for the ability of an immunetype receptor to generate signaling responses to collagen and for the development of GPVI inhibitors as new therapies for human cardiovascular disease.

  12. Quantification of three-dimensional cell-mediated collagen remodeling using graph theory.

    Directory of Open Access Journals (Sweden)

    Cemal Cagatay Bilgin

    Full Text Available BACKGROUND: Cell cooperation is a critical event during tissue development. We present the first precise metrics to quantify the interaction between mesenchymal stem cells (MSCs and extra cellular matrix (ECM. In particular, we describe cooperative collagen alignment process with respect to the spatio-temporal organization and function of mesenchymal stem cells in three dimensions. METHODOLOGY/PRINCIPAL FINDINGS: We defined two precise metrics: Collagen Alignment Index and Cell Dissatisfaction Level, for quantitatively tracking type I collagen and fibrillogenesis remodeling by mesenchymal stem cells over time. Computation of these metrics was based on graph theory and vector calculus. The cells and their three dimensional type I collagen microenvironment were modeled by three dimensional cell-graphs and collagen fiber organization was calculated from gradient vectors. With the enhancement of mesenchymal stem cell differentiation, acceleration through different phases was quantitatively demonstrated. The phases were clustered in a statistically significant manner based on collagen organization, with late phases of remodeling by untreated cells clustering strongly with early phases of remodeling by differentiating cells. The experiments were repeated three times to conclude that the metrics could successfully identify critical phases of collagen remodeling that were dependent upon cooperativity within the cell population. CONCLUSIONS/SIGNIFICANCE: Definition of early metrics that are able to predict long-term functionality by linking engineered tissue structure to function is an important step toward optimizing biomaterials for the purposes of regenerative medicine.

  13. Estrogen-induced collagen reorientation correlates with sympathetic denervation of the rat myometrium.

    Science.gov (United States)

    Martínez, G F; Bianchimano, P; Brauer, M M

    2016-12-01

    Estrogen inhibits the growth and causes the degeneration (pruning) of sympathetic nerves supplying the rat myometrium. Previous cryoculture studies evidenced that substrate-bound signals contribute to diminish the ability of the estrogenized myometrium to support sympathetic nerve growth. Using electron microscopy, here we examined neurite-substrate interactions in myometrial cryocultures, observing that neurites grew associated to collagen fibrils present in the surface of the underlying cryosection. In addition, we assessed quantitatively the effects of estrogen on myometrial collagen organization in situ, using ovariectomized rats treated with estrogen and immature females undergoing puberty. Under low estrogen levels, most collagen fibrils were oriented in parallel to the muscle long axis (83% and 85%, respectively). Following estrogen treatment, 89% of fibrils was oriented perpendicularly to the muscle main axis; while after puberty, 57% of fibrils acquired this orientation. Immunohistochemistry combined with histology revealed that the vast majority of fine sympathetic nerve fibers supplying the myometrium courses within the areas where collagen realignment was observed. Finally, to assess whether depending on their orientation collagen fibrils can promote or inhibit neurite outgrowth, we employed cryocultures, now using as substrate tissue sections of rat-tail tendon. We observed that neurites grew extensively in the direction of the parallel-aligned collagen fibrils in the tendon main axis but were inhibited to grow perpendicularly to this axis. Collectively, these findings support the hypothesis that collagen reorientation may be one of the factors contributing to diminish the neuritogenic capacity of the estrogen-primed myometrial substrate.

  14. The involvement of collagen triple helix repeat containing 1 in muscular dystrophies.

    Science.gov (United States)

    Spector, Itai; Zilberstein, Yael; Lavy, Adi; Genin, Olga; Barzilai-Tutsch, Hila; Bodanovsky, Ana; Halevy, Orna; Pines, Mark

    2013-03-01

    Fibrosis is the main complication of muscular dystrophies. We identified collagen triple helix repeat containing 1 (Cthrc1) in skeletal and cardiac muscles of mice, representing Duchenne and congenital muscle dystrophies (DMD and CMD, respectively), and dysferlinopathy. In all of the mice, Cthrc1 was associated with high collagen type I levels; no Cthrc1 or collagen was observed in muscles of control mice. High levels of Cthrc1 were also observed in biopsy specimens from patients with DMD, in whom they were reversibly correlated with that of β-dystroglycan, whereas collagen type I levels were elevated in all patients with DMD. At the muscle sites where collagen and Cthrc1 were adjacent, collagen fibers appeared smaller, suggesting involvement of Cthrc1 in collagen turnover. Halofuginone, an inhibitor of Smad3 phosphorylation downstream of the transforming growth factor-β signaling, reduced Cthrc1 levels in skeletal and cardiac muscles of mice, representing DMD, CMD, and dysferlinopathy. The myofibroblasts infiltrating the dystrophic muscles of the murine models of DMD, CMD, and dysferlinopathy were the source of Cthrc1. Transforming growth factor-β did not affect Cthrc1 levels in the mdx fibroblasts but decreased them in the control fibroblasts, in association with increased migration of mdx fibroblasts and dystrophic muscle invasion by myofibroblasts. To our knowledge, this is the first demonstration of Cthrc1 as a marker of the severity of the disease progression in the dystrophic muscles, and as a possible target for therapy.

  15. Methacrylation induces rapid, temperature-dependent, reversible self-assembly of type-I collagen.

    Science.gov (United States)

    Drzewiecki, Kathryn E; Parmar, Avanish S; Gaudet, Ian D; Branch, Jonathan R; Pike, Douglas H; Nanda, Vikas; Shreiber, David I

    2014-09-23

    Type-I collagen self-assembles into a fibrillar gel at physiological temperature and pH to provide a cell-adhesive, supportive, structural network. As such, it is an attractive, popular scaffold for in vitro evaluations of cellular behavior and for tissue engineering applications. In this study, type-I collagen is modified to introduce methacrylate groups on the free amines of the lysine residues to create collagen methacrylamide (CMA). CMA retains the properties of collagen such as self-assembly, biodegradability, and natural bioactivity but is also photoactive and can be rapidly cross-linked or functionalized with acrylated molecules when irradiated with ultraviolet light in the presence of a photoinitiator. CMA also demonstrates unique temperature-dependent behavior. For natural type-I collagen, the overall structure of the fiber network remains largely static over time scales of a few hours upon heating and cooling at temperatures below its denaturation point. CMA, however, is rapidly thermoreversible and will oscillate between a liquid macromer suspension and a semisolid fibrillar hydrogel when the temperature is modulated between 10 and 37 °C. Using a series of mechanical, scattering, and spectroscopic methods, we demonstrate that structural reversibility is manifest across multiple scales from the protein topology of the triple helix up through the rheological properties of the CMA hydrogel. Electron microscopy imaging of CMA after various stages of heating and cooling shows that the canonical collagen-like D-periodic banding ultrastructure of the fibers is preserved. A rapidly thermoreversible collagen-based hydrogel is expected to have wide utility in tissue engineering and drug delivery applications as a biofunctional, biocompatible material. Thermal reversibility also makes CMA a powerful model for studying the complex process of hierarchical collagen self-assembly.

  16. Structure to function: Spider silk and human collagen

    Science.gov (United States)

    Rabotyagova, Olena S.

    Nature has the ability to assemble a variety of simple molecules into complex functional structures with diverse properties. Collagens, silks and muscles fibers are some examples of fibrous proteins with self-assembling properties. One of the great challenges facing Science is to mimic these designs in Nature to find a way to construct molecules that are capable of organizing into functional supra-structures by self-assembly. In order to do so, a construction kit consisting of molecular building blocks along with a complete understanding on how to form functional materials is required. In this current research, the focus is on spider silk and collagen as fibrous protein-based biopolymers that can shed light on how to generate nanostructures through the complex process of self-assembly. Spider silk in fiber form offers a unique combination of high elasticity, toughness, and mechanical strength, along with biological compatibility and biodegrability. Spider silk is an example of a natural block copolymer, in which hydrophobic and hydrophilic blocks are linked together generating polymers that organize into functional materials with extraordinary properties. Since silks resemble synthetic block copolymer systems, we adopted the principles of block copolymer design from the synthetic polymer literature to build block copolymers based on spider silk sequences. Moreover, we consider spider silk to be an important model with which to study the relationships between structure and properties in our system. Thus, the first part of this work was dedicated to a novel family of spider silk block copolymers, where we generated a new family of functional spider silk-like block copolymers through recombinant DNA technology. To provide fundamental insight into relationships between peptide primary sequence, block composition, and block length and observed morphological and structural features, we used these bioengineered spider silk block copolymers to study secondary structure

  17. Collagen thermal denaturation study for thermal angioplasty based on modified kinetic model: relation between the artery mechanical properties and collagen denaturation rate

    Science.gov (United States)

    Shimazaki, N.; Hayashi, T.; Kunio, M.; Arai, T.

    2010-02-01

    We have been developing the novel short-term heating angioplasty in which sufficient artery lumen-dilatation was attained with thermal softening of collagen fiber in artery wall. In the present study, we investigated on the relation between the mechanical properties of heated artery and thermal denaturation fractures of arterial collagen in ex vivo. We employed Lumry-Eyring model to estimate temperature- and time-dependent thermal denaturation fractures of arterial collagen fiber during heating. We made a kinetic model of arterial collagen thermal denaturation by adjustment of K and k in this model, those were the equilibrium constant of reversible denaturation and the rate constant of irreversible denaturation. Meanwhile we demonstrated that the change of reduced scattering coefficient of whole artery wall during heating reflected the reversible denaturation of the collagen in artery wall. Based on this phenomenon, the K was determined experimentally by backscattered light intensity measurement (at 633nm) of extracted porcine carotid artery during temperature elevation and descending (25°C-->80°C-->25°C). We employed the value of according to our earlier report in which the time-and temperature- dependent irreversible denaturation amount of the artery collagen fiber that was assessed by the artery birefringence. Then, the time- and temperature- dependent reversible (irreversible) denaturation fraction defined as the reversible ((irreversible) denatured collagen amount) / (total collagen amount) was calculated by the model. Thermo-mechanical analysis of artery wall was performed to compare the arterial mechanical behaviors (softening, shrinkage) during heating with the calculated denaturation fraction with the model. In any artery temperature condition in 70-80°, the irreversible denaturation fraction at which the artery thermal shrinkage started was estimated to be around 20%. On the other hand, the calculated irreversible denaturation fraction remained below

  18. Changes in histoanatomical distribution of types I, III and V collagen promote adaptative remodeling in posterior tibial tendon rupture

    Directory of Open Access Journals (Sweden)

    Érika Satomi

    2008-01-01

    Full Text Available INTRODUCTION: Posterior tibial tendon dysfunction is a common cause of adult flat foot deformity, and its etiology is unknown. PURPOSE: In this study, we characterized the morphologic pattern and distribution of types I, III and V collagen in posterior tibial tendon dysfunction. METHOD: Tendon samples from patients with and without posterior tibial tendon dysfunction were stained by immunofluorescence using antibodies against types I, III and V collagen. RESULTS: Control samples showed that type V deposited near the vessels only, while surgically obtained specimens displayed type V collagen surrounding other types of collagen fibers in thicker adventitial layers. Type III collagen levels were also increased in pathological specimens. On the other hand, amounts of collagen type I, which represents 95% of the total collagen amount in normal tendon, were decreased in pathological specimens. CONCLUSION: Fibrillogenesis in posterior tibial tendon dysfunction is altered due to higher expression of types III and V collagen and a decreased amount of collagen type I, which renders the originating fibrils structurally less resistant to mechanical forces.

  19. Oriented Collagen Scaffolds for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Shohta Kodama

    2012-03-01

    Full Text Available Oriented collagen scaffolds were developed in the form of sheet, mesh and tube by arraying flow-oriented collagen string gels and dehydrating the arrayed gels. The developed collagen scaffolds can be any practical size with any direction of orientation for tissue engineering applications. The birefringence of the collagen scaffolds was quantitatively analyzed by parallel Nicols method. Since native collagen in the human body has orientations such as bone, cartilage, tendon and cornea, and the orientation has a special role for the function of human organs, the developed various types of three-dimensional oriented collagen scaffolds are expected to be useful biomaterials for tissue engineering and regenerative medicines.

  20. In vivo observation of age-related structural changes of dermal collagen in human facial skin using collagen-sensitive second harmonic generation microscope equipped with 1250-nm mode-locked Cr:Forsterite laser

    Science.gov (United States)

    Yasui, Takeshi; Yonetsu, Makoto; Tanaka, Ryosuke; Tanaka, Yuji; Fukushima, Shu-ichiro; Yamashita, Toyonobu; Ogura, Yuki; Hirao, Tetsuji; Murota, Hiroyuki; Araki, Tsutomu

    2013-03-01

    In vivo visualization of human skin aging is demonstrated using a Cr:Forsterite (Cr:F) laser-based, collagen-sensitive second harmonic generation (SHG) microscope. The deep penetration into human skin, as well as the specific sensitivity to collagen molecules, achieved by this microscope enables us to clearly visualize age-related structural changes of collagen fiber in the reticular dermis. Here we investigated intrinsic aging and/or photoaging in the male facial skin. Young subjects show dense distributions of thin collagen fibers, whereas elderly subjects show coarse distributions of thick collagen fibers. Furthermore, a comparison of SHG images between young and elderly subjects with and without a recent life history of excessive sun exposure show that a combination of photoaging with intrinsic aging significantly accelerates skin aging. We also perform image analysis based on two-dimensional Fourier transformation of the SHG images and extracted an aging parameter for human skin. The in vivo collagen-sensitive SHG microscope will be a powerful tool in fields such as cosmeceutical sciences and anti-aging dermatology.

  1. Surface modification of nanofibrous polycaprolactone/gelatin composite scaffold by collagen type I grafting for skin tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Sneh [Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee (India); Chou, Chia-Fu [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Dinda, Amit K. [Department of Pathology, All India Institute of Medical Science, New Delhi (India); Potdar, Pravin D. [Department of Molecular Medicine and Biology, Jaslok Hospital and Research Centre, Mumbai (India); Mishra, Narayan C., E-mail: mishrawise@gmail.com [Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee (India)

    2014-01-01

    In the present study, a tri-polymer polycaprolactone (PCL)/gelatin/collagen type I composite nanofibrous scaffold has been fabricated by electrospinning for skin tissue engineering and wound healing applications. Firstly, PCL/gelatin nanofibrous scaffold was fabricated by electrospinning using a low cost solvent mixture [chloroform/methanol for PCL and acetic acid (80% v/v) for gelatin], and then the nanofibrous PCL/gelatin scaffold was modified by collagen type I (0.2–1.5 wt.%) grafting. Morphology of the collagen type I-modified PCL/gelatin composite scaffold that was analyzed by field emission scanning electron microscopy (FE-SEM), showed that the fiber diameter was increased and pore size was decreased by increasing the concentration of collagen type I. Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated the surface modification of PCL/gelatin scaffold by collagen type I immobilization on the surface of the scaffold. MTT assay demonstrated the viability and high proliferation rate of L929 mouse fibroblast cells on the collagen type I-modified composite scaffold. FE-SEM analysis of cell-scaffold construct illustrated the cell adhesion of L929 mouse fibroblasts on the surface of scaffold. Characteristic cell morphology of L929 was also observed on the nanofiber mesh of the collagen type I-modified scaffold. Above results suggest that the collagen type I-modified PCL/gelatin scaffold was successful in maintaining characteristic shape of fibroblasts, besides good cell proliferation. Therefore, the fibroblast seeded PCL/gelatin/collagen type I composite nanofibrous scaffold might be a potential candidate for wound healing and skin tissue engineering applications. - Highlights: • PCL/gelatin/collagen type I scaffold was fabricated for skin tissue engineering. • PCL/gelatin/collagen type I scaffold showed higher fibroblast growth than PCL/gelatin one. • PCL/gelatin/collagen type I might be one of the ideal scaffold for

  2. Modeling pulmonary fibrosis by abnormal expression of telomerase/apoptosis/collagen V in experimental usual interstitial pneumonia

    Energy Technology Data Exchange (ETDEWEB)

    Parra, E.R.; Pincelli, M.S. [Departamento de Patologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Teodoro, W.R.; Velosa, A.P.P. [Disciplina de Reumatologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Martins, V.; Rangel, M.P.; Barbas-Filho, J.V.; Capelozzi, V.L. [Departamento de Patologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil)

    2014-06-04

    Limitations on tissue proliferation capacity determined by telomerase/apoptosis balance have been implicated in pathogenesis of idiopathic pulmonary fibrosis. In addition, collagen V shows promise as an inductor of apoptosis. We evaluated the quantitative relationship between the telomerase/apoptosis index, collagen V synthesis, and epithelial/fibroblast replication in mice exposed to butylated hydroxytoluene (BHT) at high oxygen concentration. Two groups of mice were analyzed: 20 mice received BHT, and 10 control mice received corn oil. Telomerase expression, apoptosis, collagen I, III, and V fibers, and hydroxyproline were evaluated by immunohistochemistry, in situ detection of apoptosis, electron microscopy, immunofluorescence, and histomorphometry. Electron microscopy confirmed the presence of increased alveolar epithelial cells type 1 (AEC1) in apoptosis. Immunostaining showed increased nuclear expression of telomerase in AEC type 2 (AEC2) between normal and chronic scarring areas of usual interstitial pneumonia (UIP). Control lungs and normal areas from UIP lungs showed weak green birefringence of type I and III collagens in the alveolar wall and type V collagen in the basement membrane of alveolar capillaries. The increase in collagen V was greater than collagens I and III in scarring areas of UIP. A significant direct association was found between collagen V and AEC2 apoptosis. We concluded that telomerase, collagen V fiber density, and apoptosis evaluation in experimental UIP offers the potential to control reepithelization of alveolar septa and fibroblast proliferation. Strategies aimed at preventing high rates of collagen V synthesis, or local responses to high rates of cell apoptosis, may have a significant impact in pulmonary fibrosis.

  3. Articular cartilage collagen: an irreplaceable framework?

    Directory of Open Access Journals (Sweden)

    D R Eyre

    2006-11-01

    Full Text Available Adult articular cartilage by dry weight is two-thirds collagen. The collagen has a unique molecular phenotype. The nascent type II collagen fibril is a heteropolymer, with collagen IX molecules covalently linked to the surface and collagen XI forming the filamentous template of the fibril as a whole. The functions of collagens IX and XI in the heteropolymer are far from clear but, evidently, they are critically important since mutations in COLIX and COLXI genes can result in chondrodysplasia syndromes. Here we review what is known of the collagen assembly and present new evidence that collagen type III becomes covalently added to the polymeric fabric of adult human articular cartilage, perhaps as part of a matrix repair or remodelling process.

  4. Enhanced stabilization of collagen by furfural.

    Science.gov (United States)

    Lakra, Rachita; Kiran, Manikantan Syamala; Usha, Ramamoorthy; Mohan, Ranganathan; Sundaresan, Raja; Korrapati, Purna Sai

    2014-04-01

    Furfural (2-furancarboxaldehyde), a product derived from plant pentosans, has been investigated for its interaction with collagen. Introduction of furfural during fibril formation enhanced the thermal and mechanical stability of collagen. Collagen films treated with furfural exhibited higher denaturation temperature (Td) (pcollagen films did not have any cytotoxic effect. Rheological characterization showed an increase in shear stress and shear viscosity with increasing shear rate for treated collagen. Circular dichroism (CD) studies indicated that the furfural did not have any impact on triple helical structure of collagen. Scanning electron microscopy (SEM) of furfural treated collagen exhibited small sized porous structure in comparison with untreated collagen. Thus this study provides an alternate ecologically safe crosslinking agent for improving the stability of collagen for biomedical and industrial applications.

  5. [Disc electrophoresis of collagen protein (author's transl)].

    Science.gov (United States)

    Reitmayr, P; Verzár, F

    1975-01-01

    The composition of proteins extracted from tendon collagen is investigated by disc electrophoresis. No qualitative differences can be demonstrated between young and old collagen. The action of formaldehyde and methionine on the tendons has no effect on the electrophoretic picture.

  6. Collagen Mimetic Peptides: Progress Towards Functional Applications

    OpenAIRE

    Yu, S. Michael; Li, Yang; Kim, Daniel

    2011-01-01

    Traditionally, collagen mimetic peptides (CMPs) have been used for elucidating the structure of the collagen triple helix and the factors responsible for its stabilization. The wealth of fundamental knowledge on collagen structure and cell-extracellular matrix (ECM) interactions accumulated over the past decades has led to a recent burst of research exploring the potential of CMPs to recreate the higher order assembly and biological function of natural collagens for biomedical applications. A...

  7. Biology, chemistry and pathology of collagen

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmajer, R.; Olsen, B.R.; Kuhn, K.

    1985-01-01

    This book consists of five parts and a section of poster papers. Some of the articles are: Structure of the Type II Collagen Gene; Structural and Functional Analysis of the Genes for ..cap alpha..2(1) and ..cap alpha..1(III) collagens; Structure and Expression of the Collagen Genes of C. Elegans; Molecular Basis of Clinical Heterogeneity in the Ehlers-Danlos Syndrome; and Normal and Mutant Human Collagen Genes.

  8. Laminin peptide YIGSR induces collagen synthesis in Hs27 human dermal fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jong Hyuk; Kim, Jaeyoon; Lee, Hyeongjoo [NovaCell Technology Inc., Pohang, Kyungbuk 790-784 (Korea, Republic of); Kim, So Young [Department of Dermatology, Chung-Ang University College of Medicine, Seoul 156-756 (Korea, Republic of); Department of Convergence Medicine and Pharmaceutical Biosciences, Graduate School, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Jang, Hwan-Hee [Functional Food and Nutrition Division, Department of Agrofood Resources, Rural Development Administration, Suwon 441-853 (Korea, Republic of); Ryu, Sung Ho [Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784 (Korea, Republic of); Kim, Beom Joon [Department of Dermatology, Chung-Ang University College of Medicine, Seoul 156-756 (Korea, Republic of); Department of Convergence Medicine and Pharmaceutical Biosciences, Graduate School, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Lee, Taehoon G., E-mail: taehoon@novacelltech.com [NovaCell Technology Inc., Pohang, Kyungbuk 790-784 (Korea, Republic of)

    2012-11-23

    Highlights: Black-Right-Pointing-Pointer We identify a function of the YIGSR peptide to enhance collagen synthesis in Hs27. Black-Right-Pointing-Pointer YIGSR peptide enhanced collagen type 1 synthesis both of gene and protein levels. Black-Right-Pointing-Pointer There were no changes in cell proliferation and MMP-1 level in YIGSR treatment. Black-Right-Pointing-Pointer The YIGSR effect on collagen synthesis mediated activation of FAK, pyk2 and ERK. Black-Right-Pointing-Pointer The YIGSR-induced FAK and ERK activation was modulated by FAK and MEK inhibitors. -- Abstract: The dermal ECM is synthesized from fibroblasts and is primarily compromised of fibrillar collagen and elastic fibers, which support the mechanical strength and resiliency of skin, respectively. Laminin, a major glycoprotein located in the basement membrane, promotes cell adhesion, cell growth, differentiation, and migration. The laminin tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptide, corresponding to the 929-933 sequence of the {beta}1 chain, is known to be a functional motif with effects on the inhibition of tumor metastasis, the regulation of sensory axonal response and the inhibition of angiogenesis through high affinity to the 67 kDa laminin receptor. In this study, we identified a novel function of the YIGSR peptide to enhance collagen synthesis in human dermal fibroblasts. To elucidate this novel function regarding collagen synthesis, we treated human dermal fibroblasts with YIGSR peptide in both a time- and dose-dependent manner. According to subsequent experiments, we found that the YIGSR peptide strongly enhanced collagen type 1 synthesis without changing cell proliferation or cellular MMP-1 level. This YIGSR peptide-mediated collagen type 1 synthesis was modulated by FAK inhibitor and MEK inhibitor. This study clearly reveals that YIGSR peptide plays a novel function on the collagen type 1 synthesis of dermal fibroblasts and also suggests that YIGSR is a strong candidate

  9. Predicting bulk mechanical properties of cellularized collagen gels using multiphoton microscopy.

    Science.gov (United States)

    Raub, C B; Putnam, A J; Tromberg, B J; George, S C

    2010-12-01

    Cellularized collagen gels are a common model in tissue engineering, but the relationship between the microstructure and bulk mechanical properties is only partially understood. Multiphoton microscopy (MPM) is an ideal non-invasive tool for examining collagen microstructure, cellularity and crosslink content in these gels. In order to identify robust image parameters that characterize microstructural determinants of the bulk elastic modulus, we performed serial MPM and mechanical tests on acellular and cellularized (normal human lung fibroblasts) collagen hydrogels, before and after glutaraldehyde crosslinking. Following gel contraction over 16 days, cellularized collagen gel content approached that of native connective tissues (∼200 mg ml⁻¹). Young's modulus (E) measurements from acellular collagen gels (range 0.5-12 kPa) exhibited a power-law concentration dependence (range 3-9 mg ml⁻¹) with exponents from 2.1 to 2.2, similar to other semiflexible biopolymer networks such as fibrin and actin. In contrast, cellularized collagen gel stiffness (range 0.5-27 kPa) produced concentration-dependent exponents of 0.7 uncrosslinked and 1.1 crosslinked (range ∼5-200 mg ml⁻¹). The variation in E of cellularized collagen hydrogels can be explained by a power-law dependence on robust image parameters: either the second harmonic generation (SHG) and two-photon fluorescence (TPF) (matrix component) skewness (R²=0.75, exponents of -1.0 and -0.6, respectively); or alternatively the SHG and TPF (matrix component) speckle contrast (R²=0.83, exponents of -0.7 and -1.8, respectively). Image parameters based on the cellular component of TPF signal did not improve the fits. The concentration dependence of E suggests enhanced stress relaxation in cellularized vs. acellular gels. SHG and TPF image skewness and speckle contrast from cellularized collagen gels can predict E by capturing mechanically relevant information on collagen fiber, cell and crosslink density.

  10. Synthesis of reduced collagen crosslinks

    NARCIS (Netherlands)

    Nieuwendijk, A.M.C.H. van den; Benningshof, J.C.J.; Wegmann, V.; Bank, R.A.; Koppele, J.M. te; Brussee, J.; Gen, A. van der

    1999-01-01

    A new synthetic route to reduced collagen crosslinks (LNL and HLNL) is described in this report. It enables an enantioselective synthesis of LNL. HLNL was obtained as a mixture of two diastereoisomers. This method also provides the possibility to introduce radio-labels during the synthesis.

  11. Fracture mechanics of collagen fibrils

    DEFF Research Database (Denmark)

    Svensson, Rene B; Mulder, Hindrik; Kovanen, Vuokko

    2013-01-01

    Tendons are important load-bearing structures, which are frequently injured in both sports and work. Type I collagen fibrils are the primary components of tendons and carry most of the mechanical loads experienced by the tissue, however, knowledge of how load is transmitted between and within...

  12. Synthesis of reduced collagen crosslinks

    NARCIS (Netherlands)

    Nieuwendijk, A.M.C.H. van den; Benningshof, J.C.J.; Wegmann, V.; Bank, R.A.; Koppele, J.M. te; Brussee, J.; Gen, A. van der

    1999-01-01

    A new synthetic route to reduced collagen crosslinks (LNL and HLNL) is described in this report. It enables an enantioselective synthesis of LNL. HLNL was obtained as a mixture of two diastereoisomers. This method also provides the possibility to introduce radio-labels during the synthesis.

  13. A collagen defect in homocystinuria.

    Science.gov (United States)

    Kang, A H; Trelstad, R L

    1973-10-01

    The biochemical mechanism accounting for the connective tissue abnormalities in homocystinuria was explored by examining the effects of various amino acids known to accumulate in the plasma of patients with this disease on cross-link formation in collagen. Neutral salt solutions of purified, rat skin collagen, rich in cross-link precursor aldehydes, were polymerized to native type fibrils by incubating at 37 degrees C in the presence of homocysteine, homocystine, or methionine. After the polymerization was completed, each sample was examined for the formation of covalent intermolecular cross-links, assessed indirectly by solubility tests and directly by measuring the cross-link compounds after reduction with tritiated sodium borohydride and hydrolysis. Collagen solutions containing homocysteine (0.01 M-0.1 M) failed to form insoluble fibrils. Furthermore, much less of the reducible cross-links, Delta(6,7) dehydrohydroxylysinonorleucine, Delta(6,7) dehydrohydroxylysinohydroxynorleucine, and histidino-dehydrohydroxymerodesmosine were formed in the preparations containing homocysteine as compared with the control and the samples containing methionine or homocystine. The content of the precursor aldehydes, alpha-aminoadipic-delta-semialdehyde (allysine) and the aldol condensation product, was also markedly diminished in tropocollagen incubated with homocysteine. It is concluded that homocysteine interferes with the formation of intermolecular cross-links that help stabilize the collagen macromolecular network via its reversible binding to the aldehydic functional groups. Analysis of the collagen cross-links in skin biopsy samples obtained from three patients with documented homocystinuria showed that the cross-links were significantly decreased as compared with the age-matched controls, supporting the tentative conclusions reached from the in vitro model studies. In addition, the solubility of dermal collagen in non-denaturing solvents was significantly increased in

  14. Light-emitting diode therapy increases collagen deposition during the repair process of skeletal muscle.

    Science.gov (United States)

    de Melo, Claudia Aparecida Viana; Alves, Agnelo Neves; Terena, Stella Maris Lins; Fernandes, Kristianne Porta Santos; Nunes, Fábio Daumas; da Silva, Daniela de Fátima Teixeira; Bussadori, Sandra Kalil; Deana, Alessandro Melo; Mesquita-Ferrari, Raquel Agnelli

    2016-04-01

    This study analyzed the effects of light-emitting diode (LED) therapy on the morphology of muscle tissue as well as collagen remodeling and matrix metalloproteinase 2 (MMP-2) activity in the skeletal muscle of rats following acute injury. Wistar rats were divided into four groups: (1) control, (2) sham, (3) untreated cryoinjury, and (4) cryoinjury treated with LED. Cryoinjury was induced by two applications of a metal probe cooled in liquid nitrogen directly onto the belly of the tibialis anterior muscle. For treatment, the LED equipment (wavelength 850 nm, output power 30 mW, and total energy 3.2 J) was used daily. The study periods were 1, 3, and 7 days after cryoinjury. Morphological aspects were evaluated through hematoxylin-eosin staining. The amount of collagen fibers was evaluated using Picro Sirius Red staining under polarized light. The gelatinase activity of MMP-2 was evaluated using zymography. The results showed significant reductions in inflammatory infiltrate after 3 days and an increased number of immature muscle fibers after 7 days. Furthermore, treatment induced a reduction in the gelatinolytic activity of MMP-2 after 1, 3, and 7 days in comparison to the untreated injury groups and increased the collagen deposition after 3 and 7 days in the treated groups. LED therapy at 850 nm induced a significant reduction in inflammation, decreased MMP-2 activity, and increased the amount of immature muscle and collagen fibers during the muscle repair process following acute injury.

  15. Quantifying degradation of collagen in ancient manuscripts: the case of the Dead Sea Temple Scroll.

    Science.gov (United States)

    Schütz, R; Bertinetti, L; Rabin, I; Fratzl, P; Masic, A

    2013-10-07

    Since their discovery in the late 1940s, the Dead Sea Scrolls, some 900 ancient Jewish texts, have never stopped attracting the attention of scholars and the broad public alike, because they were created towards the end of the Second Temple period and the "time of Christ". Most of the work on them has been dedicated to the information contained in the scrolls' text, leaving physical aspects of the writing materials unexamined. They are, however, crucial for both historical insight and preservation of the scrolls. Although scientific analysis requires handling, it is essential to establish the state of degradation of these valued documents. Polarized Raman Spectroscopy (PRS) is a powerful tool for obtaining information on both the composition and the level of disorder of molecular units. In this study, we developed a non-invasive and non-destructive methodology that allows a quantification of the disorder (that can be related to the degradation) of protein molecular units in collagen fibers. Not restricted to collagen, this method can be applied also to other protein-based fibrous materials such as ancient silk, wool or hair. We used PRS to quantify the degradation of the collagen fibers in a number of fragments of the Temple Scroll (11Q19a). We found that collagen fibers degrade heterogeneously, with the ones on the surface more degraded than those in the core.

  16. A comparative analysis of the collagen architecture in the carotid artery: second harmonic generation versus diffusion tensor imaging.

    Science.gov (United States)

    Ghazanfari, S; Driessen-Mol, A; Strijkers, G J; Kanters, F M W; Baaijens, F P T; Bouten, C V C

    2012-09-14

    Collagen is the main load-bearing component of the artery. The 3D arrangement of the collagen fibers is crucial to understand the mechanical behavior of such tissues. We compared collagen fiber alignment obtained by second harmonic generation (SHG) microscopy with the alignment obtained by diffusion tensor imaging (DTI) throughout the wall of a porcine carotid artery to check the feasibility of using DTI as a fast and non-destructive method instead of SHG. The middle part of the artery was cut into two segments: one for DTI and one for the SHG measurements. The tissue for SHG measurements was cut into 30μm tangential sections. After scanning all sections, they were registered together and the fiber orientation was quantified by an in-house algorithm. The tissue for DTI measurement was embedded in type VII agarose and scanned with an MRI-scanner. Fiber tractography was performed on the DTI images. Both methods showed a layered structure of the wall. The fibers were mainly oriented circumferentially in the outer adventitia and media. DTI revealed the predominant layers of the arterial wall. This study showed the feasibility of using DTI for evaluating the collagen orientation in native artery as a fast and non-destructive method. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Monitoring the effect of magnetically aligned collagen scaffolds on tendon tissue engineering by PSOCT

    Science.gov (United States)

    Yang, Ying; Ahearne, Mark; Wimpenny, Ian; Torbet, Jim

    2009-02-01

    As the repair of injured or degenerated tendon is often compromised by the shortage of suitable donor tissue, other procedures need to be developed. The application of a functional tissue engineered tendon could prove to be a promising alternative therapy. Due to their good biocompatibility, collagen hydrogel based scaffolds have been considered to be potentially suitable for engineering tendon tissue in vitro. One of the major limitations of collagen hydrogels for engineering tissues is the difficulty in controlling their architecture and collagen concentration which results in poor mechanical strength. This study aims to overcome these limitations by creating a highly biocompatible scaffold that is both mechanically robust and aligned. Collagen fibers were pre-aligned under a high magnetic field then concentrated using plastic compression. Primary tenocytes cultured from rats were seeded on the aligned scaffolds. Following a protocol in public domain, thick cultured collagen constructs were rolled up into a spiral after undergoing plastic compressed. Both a light microscopy and a polarization sensitive optical coherence tomography (PSOCT) with central beam at 1300 nm were used to monitor the birefringence in the constructs. Conventional light microscopy showed that the tenocytes aligned along the pre-organized collagen bundles in contrast to the random distributed observed on unaligned scaffolds. PSOCT only revealed weak birefringence from aligned but uncompressed constructs. However, PSOCT images showed contrast band structures in the spiral constructs which suggests that the birefringence signal depends on the density of aligned collagen fibers. The effect of aligned cells, neo-formed matrix and the plastic compression on the birefringence signals are discussed in this paper briefly.

  18. Surface modification of electrospun PLGA scaffold with collagen for bioengineered skin substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, A.R., E-mail: sadeghi_av@ymail.com [Materials Research Group, Iranian Academic Center for Education, Culture and Research, (ACECR), Mashhad Branch, Mashhad (Iran, Islamic Republic of); Nokhasteh, S. [Materials Research Group, Iranian Academic Center for Education, Culture and Research, (ACECR), Mashhad Branch, Mashhad (Iran, Islamic Republic of); Molavi, A.M. [Materials Research Group, Iranian Academic Center for Education, Culture and Research, (ACECR), Mashhad Branch, Mashhad (Iran, Islamic Republic of); Materials Engineering Department, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Khorsand-Ghayeni, M. [Materials Research Group, Iranian Academic Center for Education, Culture and Research, (ACECR), Mashhad Branch, Mashhad (Iran, Islamic Republic of); Naderi-Meshkin, H. [Stem Cell and Regenerative Medicine Research Department, Iranian Academic Center for Education, Culture and Research (ACECR), Mashhad Branch, Mashhad (Iran, Islamic Republic of); Mahdizadeh, A. [Nanotechnology Institute, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of)

    2016-09-01

    In skin tissue engineering, surface feature of the scaffolds plays an important role in cell adhesion and proliferation. In this study, non-woven fibrous substrate based on poly (lactic-co-glycolic acid) (PLGA) (75/25) were hydrolyzed in various concentrations of NaOH (0.05 N, 0.1 N, 0.3 N) to increase carboxyl and hydroxyl groups on the fiber surfaces. These functional groups were activated by EDC/NHS to create chemical bonding with collagen. To improve bioactivity, the activated substrates were coated with a collagen solution (2 mg/ml) and cross-linking was carried out using the EDC/NHS in MES buffer. The effectiveness of the method was evaluated by contact angle measurements, porosimetry, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), tensile and degradation tests as well as in vitro cell attachment and cytotoxicity assays. Cell culture results of human dermal fibroblasts (HDF) and keratinocytes cell line (HaCat) revealed that the cells could attach to the scaffold. Further investigation with MTT assay showed that the cell proliferation of HaCat significantly increases with collagen coating. It seems that sufficient stability of collagen on the surface due to proper chemical bonding and cross-linking has increased the bioactivity of surface remarkably which can be promising for bioengineered skin applications. - Highlights: • Surface activation was carried out by hydrolysis of PLGA fibers. • To improve bioactivity, the activated samples were coated with a collagen solution. • Functional groups were activated by EDC/NHS to create chemical bonding with collagen. • Cross-linking of collagen was carried out using EDC/NHS in MES buffer. • The coated samples exhibited better adhesion and proliferation of epidermal cells.

  19. Recurrent laryngeal nerve regeneration using an oriented collagen scaffold containing Schwann cells.

    Science.gov (United States)

    Chitose, Shun-Ichi; Sato, Kiminori; Fukahori, Mioko; Sueyoshi, Shintaro; Kurita, Takashi; Umeno, Hirohito

    2017-07-01

    Regeneration of the recurrent laryngeal nerve (RLN), which innervates the intrinsic laryngeal muscles such that they can perform complex functions, is particularly difficult to achieve. Synkinesis after RLN neogenesis leads to uncoordinated movement of laryngeal muscles. Recently, some basic research studies have used cultured Schwann cells (SCs) to repair peripheral nerve injuries. This study aimed to regenerate the RLN using an oriented collagen scaffold containing cultured SCs. Preliminary animal experiment. A 10-mm-long autologous canine cervical ansa was harvested. The nerve tissue was scattered and subcultured on oriented collagen sheets in reduced serum medium. After verifying that the smaller cultivated cells with high nucleus-cytoplasm ratios were SCs, collagen sheets with longitudinally oriented cells were rolled and inserted into a 20-mm collagen conduit. The fabricated scaffolds containing SCs were autotransplanted to a 20-mm deficient RLN, and vocal fold movements and histological characteristics were observed. Scaffolds containing cultured SCs were successfully fabricated. Immunocytochemical examination revealed that these isolated and cultured cells, identified as SCs, expressed S-100 protein and GFAP but not vimentin. The orientation of SCs matched that of the oriented collagen sheet. Two months after successful transplantation, laryngeal endoscopy revealed coordinated movement of the bilateral vocal folds by external stimulation under light general anesthesia. Hematoxylin and eosin staining showed that the regenerated RLN lacked epineurium surrounding the nerve fibers and was interspersed with collagen fibers. Myelin protein zero was expressed around many axons. Partial regeneration of RLN was achieved through the use of oriented collagen scaffolding. NA Laryngoscope, 127:1622-1627, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

  20. Role of collagen in terahertz absorption in skin

    Science.gov (United States)

    Tewari, Priyamvada; Culjat, Martin O.; Taylor, Zachary D.; Suen, Jonathan Y.; Burt, Benjamin O.; Lee, Hua; Brown, Elliott R.; Grundfest, Warren S.; Singh, Rahul S.

    2009-02-01

    Reflective terahertz (THz) imaging may potentially become a valuable tool in determining skin hydration due to its non-ionizing photon energy, high sensitivity to water concentration and ability to penetrate through clothing. The high absorption coefficient of water in the THz range is responsible for contrast between substances with lesser or higher degrees of water saturation. Water content, as well as collagen fiber arrangement, varies between different layers of skin. This study sought to determine whether the high THz absorption in water could be exploited to distinguish between these layers. Porcine skin specimens were sectioned into samples of increasing thickness, with the undersides corresponding to different layers in skin. The undersides of the samples were scanned using a THz imaging system operating at a center frequency of 0.5 THz with 0.125 THz of noise-equivalent bandwidth at a standoff of 4 cm and a spot size of 13 mm. Collagen solutions of varying hydrations were also prepared and raster scanned with the same system. The reflectivity of the deeper layers of skin was found to be higher than that of the upper layers, indicating that the deeper layers are more hydrated. The collagen solutions with higher hydration also had higher THz reflectivity. These results suggested that THz is able to distinguish between different layers of skin based on water content and the nature of its association with components in skin.

  1. Molecular Packing in Network-Forming Collagens

    Directory of Open Access Journals (Sweden)

    Carlo Knupp

    2003-01-01

    Full Text Available Collagen is the most abundant protein among vertebrates and occurs in virtually all multicellular animals. Collagen molecules are classified into 21 different types and differ in their sequence, weight, structure, and function, but they can be broadly subdivided into families. Type IV, VI, VIII, X, and dogfish egg case collagens belong to the network-forming family. Here, we summarise what is known about the way these collagen molecules pack to form networks. In addition the main structural characteristics of the network-forming collagens are compared and discussed.

  2. A genetic anomaly of oriented collagen biosynthesis and cross-linking: Keratoconus.

    Science.gov (United States)

    Bourges, J L; Robert, A M; Robert, L

    2015-02-01

    Oriented collagen biosynthesis is one of the major mechanisms involved in tissue and organ formation during development. Corneal biogenesis is one example. Defects in this process lead to anomalies in tissue structure and function. The transparency of cornea and its achievement are a good example as well as its pathological modifications. Keratoconus is one example of this type of pathologies, involving also inappropriate cross-linking of collagen fibers. Among the tentatives to correct this anomaly, the riboflavin-potentiated UV-cross-linking (CXL) of keratoconus corneas appears clinically satisfactory, although none of the experiments and clinical results published prove effective cross-linking. The published results are reviewed in this article.

  3. Dietary Fiber

    Science.gov (United States)

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble ... types have important health benefits. Good sources of dietary fiber include Whole grains Nuts and seeds Fruit and ...

  4. Fiber Amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten

    2017-01-01

    The chapter provides a discussion of optical fiber amplifiers and through three sections provides a detailed treatment of three types of optical fiber amplifiers, erbium doped fiber amplifiers (EDFA), Raman amplifiers, and parametric amplifiers. Each section comprises the fundamentals including t...

  5. Effect of nordihydroguaiaretic acid cross-linking on fibrillar collagen: in vitro evaluation of fibroblast adhesion strength and migration

    Directory of Open Access Journals (Sweden)

    Ana Y. Rioja

    2017-04-01

    Full Text Available Fixation is required to reinforce reconstituted collagen for orthopedic bioprostheses such as tendon or ligament replacements. Previous studies have demonstrated that collagen fibers cross-linked by the biocompatible dicatechol nordihydroguaiaretic acid (NDGA have mechanical strength comparable to native tendons. This work focuses on investigating fibroblast behavior on fibrillar and NDGA cross-linked type I collagen to determine if NDGA modulates cell adhesion, morphology, and migration. A spinning disk device that applies a range of hydrodynamic forces under uniform chemical conditions was employed to sensitively quantify cell adhesion strength, and a radial barrier removal assay was used to measure cell migration on films suitable for these quantitative in vitro assays. The compaction of collagen films, mediated by the drying and cross-linking fabrication process, suggests a less open organization compared to native fibrillar collagen that likely allowed the collagen to form more inter-chain bonds and chemical links with NDGA polymers. Fibroblasts strongly adhered to and migrated on native and NDGA cross-linked fibrillar collagen; however, NDGA modestly reduced cell spreading, adhesion strength and migration rate. Thus, it is hypothesized that NDGA cross-linking masked some adhesion receptor binding sites either physically, chemically, or both, thereby modulating adhesion and migration. This alteration in the cell-material interface is considered a minimal trade-off for the superior mechanical and compatibility properties of NDGA cross-linked collagen compared to other fixation approaches.

  6. Low-cost processing technology for the synthesis of calcium phosphates/collagen biocomposites for potential bone tissue engineering applications

    Directory of Open Access Journals (Sweden)

    Maria Helena Santos

    2007-12-01

    Full Text Available In the present study two novel composites of Calcium phosphates (CaP and Collagen (COL were synthesized, hydroxyapatite/Collagen (HA/COL and hydroxyapatite-btricalcium phosphate/COL (HAbTCP/COL. Collagen was extracted from bovine pericardium submitted to enzymatic digestion and purification by ion-exchange chromatography yielding high purity grade type I collagen. Biocomposites of HAP/COL and HAbTCP/COL were produced with a calcium phosphate/COL ratio of 80/20 (wt. (% and were characterized by chemical analysis, light microscopy and scanning electron microscopy, X ray diffraction and FT-infrared spectroscopy. SEM results of the CaP powders showed agglomerates of particles at the nanometric size range with predominantly columnar shape and average chemical composition of [Ca/P] = 1.67. FTIR analysis of collagen has confirmed the major vibrational bands associated with chemical groups like amides and hydroxyls usually found in proteins. SEM micrographs have indicated that both morphological and structural features and chemical composition of the composites were very similar to their precursors, collagen and calcium phosphate components. SDS-PAGE characterization results of protein extracted and purified has showed that bovine type I collagen was successfully obtained. Finally, the biocomposites presented a homogeneous aspect with the calcium phosphate particles aggregated to the collagen fibers. Hence, the novel developed biocomposites have high potential to be used for rebuilding small lesions in bone tissue engineering.

  7. Observing Effects of Calcium/Magnesium Ions and pH Value on the Self-Assembly of Extracted Swine Tendon Collagen by Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Xuan Song

    2017-01-01

    Full Text Available Self-assembly of extracted collagen from swine trotter tendon under different conditions was firstly observed using atomic force microscopy; then the effects of collagen concentration, pH value, and metal ions to the topography of the collagen assembly were analyzed with the height images and section analysis data. Collagen assembly under 0.1 M, 0.2 M, 0.3 M CaCl2, and MgCl2 solutions in different pH values showed significant differences (P < 0.05 in the topographical properties including height, width, and roughness. With the concentration being increased, the width of collagen decreased significantly (P < 0.05. The width of collagen fibers was first increased significantly (P < 0.05 and then decreased with the increasing of pH. The collagen was assembled with network structure on the mica in solution with Ca2+ ions. However, it had shown uniformed fibrous structure with Mg2+ ions on the new cleaved mica sheet. In addition, the width of collagen fibrous was 31~58 nm in solution with Mg2+ but 21~50 nm in Ca2+ solution. The self-assembly collagen displayed various potential abilities to construct fibers or membrane on mica surfaces with Ca2+ ions and Mg2+ irons. Besides, the result of collagen self-assembly had shown more relations among solution pH value, metal ions, and collagen molecular concentration, which will provide useful information on the control of collagen self-assembly in tissue engineering and food packaging engineering.

  8. Collagen membrane alleviates peritendinous adhesion in the rat Achilles tendon injury model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Huan; GUAN Hong-geng; GU Jun; LUO Zong-ping; ZHANG Wen; CHEN Bing; GU Qiao-li

    2013-01-01

    Background Tendon adhesion is one of the most common causes of disability following tendon surgery.Therefore,prevention of peritendinous adhesion after surgical repair of tendon is a major challenge.The aim of this study was to explore the possible application of a collagen membrane for the prevention or attenuation of peritendinous adhesions.Methods Sprague-Dawley (SD) rat Achilles tendon was cut and sutured by a modified Kessler's technique with or without the collagen membrane wrapped.Macroscopic,morphological and biomechanical evaluations were applied to examine the recovery of the injured tendon at 4 and 8 weeks after surgery.Results The surgery group wrapped by collagen membranes had a better outcome than the group with surgery repair only.In the collagen membrane-treated group,less adhesion appeared,stronger tensile strength was detected,and more tendon fibers and collagen I expression were observed morphologically.Conclusion Wrapping the tendon with a collagen membrane may be an efficient approach for tendon repair and preventing tendon adhesion after its ruptures.

  9. Dynamic multiphoton imaging of reversible and irreversible thermal changes in collagen tissues

    Science.gov (United States)

    Hovhannisyan, Vladimir A.; Su, Ping-Jung; Dong, Chen-Yuan

    2011-07-01

    Collagen is the major component of skin, tendon, cartilage, cornea, and, as a main structural protein it is the key determinant of thermo-mechanical properties of collagen-rich tissues in mammals. Thermal damage of chicken dermis and tendon, bovine leg tendon, and other collagen contained tissues were investigated with the use of second harmonic generation (SHG) and two-photon excited auto-fluorescence microscopy and spectroscopy. Samples were heating in a temperature-controlled water bath in the temperature range 18-90° C. SHG time-lapse imaging and analysis of intensity decay showed that the collagen thermal destruction depended on both temperature and heating time, and can be modeled by the Arrhenius equation. Temporal decay of SHG signal from the chicken dermis was single exponential during isothermal treatment at temperatures above 60º C that allowed to determine activation energy and frequency factor of skin collagen denaturation. Furthermore, two-exponential decay and partially reversible change in SHG intensity were registered during the tendon thermal treatment. A simple laser system and procedure is proposed for a real-time monitoring of collagen fiber thermal modification within a microscopic volume of 1 nl.

  10. Extraction and characterization of highly purified collagen from bovine pericardium for potential bioengineering applications.

    Science.gov (United States)

    Santos, Maria Helena; Silva, Rafael M; Dumont, Vitor C; Neves, Juliana S; Mansur, Herman S; Heneine, Luiz Guilherme D

    2013-03-01

    Bovine pericardium is widely used as a raw material in bioengineering as a source of collagen, a fundamental structural molecule. The physical, chemical, and biocompatibility characteristics of these natural fibers enable their broad use in several areas of the health sciences. For these applications, it is important to obtain collagen of the highest possible purity. The lack of a method to produce these pure biocompatible materials using simple and economically feasible techniques presents a major challenge to their production on an industrial scale. This study aimed to extract, purify, and characterize the type I collagen protein originating from bovine pericardium, considered to be an abundant tissue resource. The pericardium tissue was collected from male animals at slaughter age. Pieces of bovine pericardium were enzymatically digested, followed by a novel protocol developed for protein purification using ion-exchange chromatography. The material was extensively characterized by electrophoresis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and infrared spectroscopy. The results showed a purified material with morphological properties and chemical functionalities compatible with type I collagen and similar to a highly purified commercial collagen. Thus, an innovative and relatively simple processing method was developed to extract and purify type I collagen from bovine tissue with potential applications as a biomaterial for regenerative tissue engineering. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Collagen cross linking: Current perspectives

    Directory of Open Access Journals (Sweden)

    Srinivas K Rao

    2013-01-01

    Full Text Available Keratoconus is a common ectatic disorder occurring in more than 1 in 1,000 individuals. The condition typically starts in adolescence and early adulthood. It is a disease with an uncertain cause and its progression is unpredictable, but in extreme cases, vision deteriorates and can require corneal transplant surgery. Corneal collagen cross-linking (CCL with riboflavin (C3R is a recent treatment option that can enhance the rigidity of the cornea and prevent disease progression. Since its inception, the procedure has evolved with newer instrumentation, surgical techniques, and is also now performed for expanded indications other than keratoconus. With increasing experience, newer guidelines regarding optimization of patient selection, the spectrum of complications and their management, and combination procedures are being described. This article in conjunction with the others in this issue, will try and explore the uses of collagen cross-linking (CXL in its current form.

  12. Water Fibers

    CERN Document Server

    Douvidzon, Mark L; Martin, Leopoldo L; Carmon, Tal

    2016-01-01

    Fibers constitute the backbone of modern communication and are used in laser surgeries; fibers also genarate coherent X-ray, guided-sound and supercontinuum. In contrast, fibers for capillary oscillations, which are unique to liquids, were rarely considered in optofluidics. Here we fabricate fibers by water bridging an optical tapered-coupler to a microlensed coupler. Our water fibers are held in air and their length can be longer than a millimeter. These hybrid fibers co-confine two important oscillations in nature: capillary- and electromagnetic-. We optically record vibrations in the water fiber, including an audio-rate fundamental and its 3 overtones in a harmonic series, that one can hear in soundtracks attached. Transforming Micro-Electro-Mechanical-Systems [MEMS] to Micro-Electro-Capillary-Systems [MECS], boosts the device softness by a million to accordingly improve its response to minute forces. Furthermore, MECS are compatible with water, which is a most important liquid in our world.

  13. [Effect of surgical laser on collagen-rich tissue].

    Science.gov (United States)

    Gebauer, D; Constantinescu, M A

    2000-01-01

    The goal of this ex-vivo study was a controlled macroscopical and microscopical comparison of the immediate effects of surgical lasers on dense collagenous tissues. The investigation of the exact denaturizing effects following tissue interaction between lasers and collagenous fibers are of importance for a better understanding of the observed and described healing process. Partial tenotomies were performed ex vivo on sixty tendons of the flexor digitorum profundus muscle of New Zealand White Rabbits using four surgical lasers (Holmium:YAG-, Erbium:YAG-, Neodym:YAG-, and CO2-Laser). The tendons were evaluated macroscopically, histologically and observations were made on the surgical handling of the lasers during the procedure. The choice of lasers allowed the comparison of a wide spectrum of wavelengths (gamma = 1.0 to 10.6 microns). In addition, beam delivery modalities were compared to each other (focus vs. contact). The pulse (frequency and power) was varied within each laser. Other parameters including focus size, absorption, dispersion, and thermal tissue conductivity were maintained constant in this test arrangement in order to allow a later comparison between the observed areas of denaturated collagen. The macroscopical and histological results showed great differences in the effects of the four lasers. Even within each single laser group, the results varied greatly with the choice of variable parameters. Holmium:YAG- and CO2-Laser can produce similar areas of collagen denaturation. When comparing specimens with similar areas of collagen denaturation induced by different laser types, different amounts of charring were observed. Erbium:YAG-Laser tenotomies showed generally inhomogeneous denaturation areas, while tenotomies with Neodym: YAG-Laser used in continuous mode resulted in significant charring and tissue retraction in the area of interaction. These observations help in defining the combination of parameters with which Holmium:YAG-, Erbium:YAG-, and CO2

  14. Alteration of cellular behavior and response to PI3K pathway inhibition by culture in 3D collagen gels.

    Directory of Open Access Journals (Sweden)

    Brian Fallica

    Full Text Available Most investigations into cancer cell drug response are performed with cells cultured on flat (2D tissue culture plastic. Emerging research has shown that the presence of a three-dimensional (3D extracellular matrix (ECM is critical for normal cell behavior including migration, adhesion, signaling, proliferation and apoptosis. In this study we investigate differences between cancer cell signaling in 2D culture and a 3D ECM, employing real-time, live cell tracking to directly observe U2OS human osteosarcoma and MCF7 human breast cancer cells embedded in type 1 collagen gels. The activation of the important PI3K signaling pathway under these different growth conditions is studied, and the response to inhibition of both PI3K and mTOR with PI103 investigated. Cells grown in 3D gels show reduced proliferation and migration as well as reduced PI3K pathway activation when compared to cells grown in 2D. Our results quantitatively demonstrate that a collagen ECM can protect U2OS cells from PI103. Overall, our data suggests that 3D gels may provide a better medium for investigation of anti-cancer drugs than 2D monolayers, therefore allowing better understanding of cellular response and behavior in native like environments.

  15. Structural changes in cartilage and collagen studied by high temperature Raman spectroscopy.

    Science.gov (United States)

    Fields, Mark; Spencer, Nicholas; Dudhia, Jayesh; McMillan, Paul F

    2017-02-22

    Understanding the high temperature behavior of collagen and collagenous tissue is important for surgical procedures and biomaterials processing for the food, pharmaceutical and cosmetics industries. One primary event for proteins is thermal denaturation that involves unfolding the polypeptide chains while maintaining the primary structure intact. Collagen in the extracellular matrix of cartilage and other connective tissue is a hierarchical material containing bundles of triple-helical fibers associated with water and proteoglycan components. Thermal analysis of dehydrated collagen indicates irreversible denaturation at high temperature between 135-200°C, with another reversible event at ∼60-80°C for hydrated samples. We report high temperature Raman spectra for freeze-dried cartilage samples that show an increase in laser-excited fluorescence interpreted as conformational changes associated with denaturation above 140°C. Spectra for separated collagen and proteoglycan fractions extracted from cartilage indicate the changes are associated with collagen. The Raman data also show appearance of new features indicating peptide bond hydrolysis at high temperature implying that molecular H2 O is retained within the freeze-dried tissue. This is confirmed by thermogravimetric analysis that show 5-7 wt% H2 O remaining within freeze-dried cartilage that is released progressively upon heating up to 200°C. Spectra obtained after exposure to high temperature and re-hydration following recovery indicate that the capacity of the denatured collagen to re-absorb water is reduced. Our results are important for revealing the presence of bound H2 O within the collagen component of connective tissue even after freeze-drying and its role in denaturation that is accompanied by or perhaps preceded by breakdown of the primary polypeptide structure. This article is protected by copyright. All rights reserved.

  16. Histological Comparison of the Human Trunk Skin Creases: The Role of the Elastic Fiber Component

    Science.gov (United States)

    Kakagia, Despoina; Yiacoumettis, Andreas; Vasilakaki, Thivi; Drougou, Aggeliki; Lambropoulou, Maria; Simopoulos, Constantinos; Tsaroucha, Alexandra K.

    2016-01-01

    Objective: Skin creases are features of major anatomical, morphological, surgical, and functional interest. This study focuses on the histological comparison of creases of the trunk and participation of the elastic fibers in their formation. The histological structure is a key consideration for the reconstructive planning of the relevant area and its knowledge may contribute in such direction. Methods: Fresh cadaver specimens were collected from the inframammary (n = 15), infragluteal (n = 16), and inguinal creases (n = 14), the anterior axillary fold (n = 14), and the surrounding skin (n = 10). Specimens were fixed in 10% buffered formaldehyde. Collagen and muscle fibers were stained by Masson Trichrome and Van Gieson stains, reticular and collagen type III fibers by Reticulin stain, and elastic fibers by Verhoef and Orcein stains. Results: Skin creases of the trunk present well-defined dense bundles of collagen fibers, creating a beehive pattern with broad attachment to the dermis and denser in deeper sites related to the fascia of the underlying muscle. The elastic fibers participate in the collagen pattern and radiate in a parallel pattern in the reticular dermis and in a perpendicular fashion in the papillary dermis. The skin surrounding the creases lacks such organization. Conclusions: Creases of the trunk are formed by well-organized collagen bundles in a beehive pattern, attached to the dermis and related to the underlying muscle fascia. The elastic fibers participate in this structure and radiate in a parallel fashion in the reticular dermis and perpendicularly in the papillary dermis. PMID:27081433

  17. Collagen metabolism of human osteoarthritic articular cartilage as modulated by bovine collagen hydrolysates.

    Directory of Open Access Journals (Sweden)

    Saskia Schadow

    Full Text Available Destruction of articular cartilage is a characteristic feature of osteoarthritis (OA. Collagen hydrolysates are mixtures of collagen peptides and have gained huge public attention as nutriceuticals used for prophylaxis of OA. Here, we evaluated for the first time whether different bovine collagen hydrolysate preparations indeed modulate the metabolism of collagen and proteoglycans from human OA cartilage explants and determined the chemical composition of oligopeptides representing collagen fragments. Using biophysical techniques, like MALDI-TOF-MS, AFM, and NMR, the molecular weight distribution and aggregation behavior of collagen hydrolysates from bovine origin (CH-Alpha®, Peptan™ B 5000, Peptan™ B 2000 were determined. To investigate the metabolism of human femoral OA cartilage, explants were obtained during knee replacement surgery. Collagen synthesis of explants as modulated by 0-10 mg/ml collagen hydrolysates was determined using a novel dual radiolabeling procedure. Proteoglycans, NO, PGE(2, MMP-1, -3, -13, TIMP-1, collagen type II, and cell viability were determined in explant cultures. Groups of data were analyzed using ANOVA and the Friedman test (n = 5-12. The significance was set to p≤0.05. We found that collagen hydrolysates obtained from different sources varied with respect to the width of molecular weight distribution, average molecular weight, and aggregation behavior. None of the collagen hydrolysates tested stimulated the biosynthesis of collagen. Peptan™ B 5000 elevated NO and PGE(2 levels significantly but had no effect on collagen or proteoglycan loss. All collagen hydrolysates tested proved not to be cytotoxic. Together, our data demonstrate for the first time that various collagen hydrolysates differ with respect to their chemical composition of collagen fragments as well as by their pharmacological efficacy on human chondrocytes. Our study underscores the importance that each collagen hydrolysate

  18. Effect of platelet age on adhesiveness to collagen and platelet surface charge

    Energy Technology Data Exchange (ETDEWEB)

    Castellan, R.M.; Steiner, M.

    1976-11-30

    Adhesion to collagen was investigated as a function of platelet age in rat platelets. Platelet adherence was measured using EDTA-containing platelet- rich plasma which was added to preparations of collagen fibers clamped between magnetic stirrers by recording changes in light transmission. The plot of light transmission versus logarithm of time was linear and allowed calculation of a slope factor which related to the rate of adherence. Neither the amount of collagen nor the platelet count were limiting in the test. Young platelet populations (less than or equal to 1 day old) were obtained during the recovery phase from immune induced thrombocytopenia. Old platelet populations were prepared by blocking thrombopoiesis with cyclophosphamide. Young platelets did not differ significantly from randomly aged platelets in this function. The electrophoretic mobility of platelets was not affected by their age.

  19. Complete Histological Resolution of Collagenous Sprue

    Directory of Open Access Journals (Sweden)

    Hugh J Freeman

    2004-01-01

    Full Text Available A 65-year-old woman developed a watery diarrhea syndrome with collagenous colitis. Later, weight loss and hypoalbuminemia were documented. This prompted small bowel biopsies that showed pathological changes of collagenous sprue. An apparent treatment response to a gluten-free diet and prednisone resulted in reduced diarrhea, weight gain and normalization of serum albumin. Later repeated biopsies from multiple small and large bowel sites over a period of over three years, however, showed reversion to normal small intestinal mucosa but persistent collagenous colitis. These results indicate that collagenous inflammatory disease may be a far more extensive process in the gastrointestinal tract than is currently appreciated. Moreover, collagenous colitis may be a clinical signal that occult small intestinal disease is present. Finally, collagenous sprue may, in some instances, be a completely reversible small intestinal disorder.

  20. Jellyfish collagen scaffolds for cartilage tissue engineering.

    Science.gov (United States)

    Hoyer, Birgit; Bernhardt, Anne; Lode, Anja; Heinemann, Sascha; Sewing, Judith; Klinger, Matthias; Notbohm, Holger; Gelinsky, Michael

    2014-02-01

    Porous scaffolds were engineered from refibrillized collagen of the jellyfish Rhopilema esculentum for potential application in cartilage regeneration. The influence of collagen concentration, salinity and temperature on fibril formation was evaluated by turbidity measurements and quantification of fibrillized collagen. The formation of collagen fibrils with a typical banding pattern was confirmed by atomic force microscopy and transmission electron microscopy analysis. Porous scaffolds from jellyfish collagen, refibrillized under optimized conditions, were fabricated by freeze-drying and subsequent chemical cross-linking. Scaffolds possessed an open porosity of 98.2%. The samples were stable under cyclic compression and displayed an elastic behavior. Cytotoxicity tests with human mesenchymal stem cells (hMSCs) did not reveal any cytotoxic effects of the material. Chondrogenic markers SOX9, collagen II and aggrecan were upregulated in direct cultures of hMSCs upon chondrogenic stimulation. The formation of typical extracellular matrix components was further confirmed by quantification of sulfated glycosaminoglycans.

  1. Synchronous Occurrence of Collagenous and Pseudomembranous Colitis

    Directory of Open Access Journals (Sweden)

    Z Vesoulis

    2000-01-01

    Full Text Available Synchronous collagenous and pseudomembranous colitis has not been previously reported. A 73-year-old woman presented with chronic watery diarrhea and abdominal cramping of six weeks’ duration. Biopsies of the colon revealed findings of collagenous colitis involving the endoscopically normal right colon, and superimposed collagenous and pseudomembranous colitis involving the rectosigmoid colon. Endoscopically, the left colon revealed discrete ulcerative plaques, and Clostridium difficile toxin A assay was positive. The patient partially responded to a three-week regimen of metronidazole, and symptoms resolved completely with subsequent steroid therapy. At follow-up endoscopy four months later, colon biopsies demonstrated persistence of subepithelial collagen but no pseudomembranes. The patient remained asymptomatic during this interval. Collagenous colitis has been reported in association with other inflammatory bowel diseases, including lymphocytic colitis, sprue and idiopathic inflammatory bowel disease. This unique association of collagenous colitis with an endotoxigenic inflammatory bowel disease is presented with a review of related disease features.

  2. Similar hyaline-like cartilage repair of osteochondral defects in rabbits using isotropic and anisotropic collagen scaffolds

    NARCIS (Netherlands)

    Mulder, E.L.W. de; Hannink, G.J.; Kuppevelt, T.H. van; Daamen, W.F.; Buma, P.

    2014-01-01

    Lesions in knee joint articular cartilage (AC) have limited repair capacity. Many clinically available treatments induce a fibrous-like cartilage repair instead of hyaline cartilage. To induce hyaline cartilage repair, we hypothesized that type I collagen scaffolds with fibers aligned perpendicular

  3. Mesothelial Cell Autoantibodies Induce Collagen Deposition in vitro & Using a Case Study to Introduce Undergraduates to Bioinformatics

    Science.gov (United States)

    Serve, Kinta M.

    2013-01-01

    Part I. Pleural fibrosis, a non-malignant, asbestos-related respiratory disease characterized by excessive collagen deposition, is progressive, debilitating, and potentially fatal. Disease severity may be influenced by the type of asbestos fiber inhaled, with Libby amphibole (LA) a seemingly more potent mediator of pleural fibrosis than chrysotile…

  4. Mesothelial Cell Autoantibodies Induce Collagen Deposition in vitro & Using a Case Study to Introduce Undergraduates to Bioinformatics

    Science.gov (United States)

    Serve, Kinta M.

    2013-01-01

    Part I. Pleural fibrosis, a non-malignant, asbestos-related respiratory disease characterized by excessive collagen deposition, is progressive, debilitating, and potentially fatal. Disease severity may be influenced by the type of asbestos fiber inhaled, with Libby amphibole (LA) a seemingly more potent mediator of pleural fibrosis than chrysotile…

  5. Collagen and matrix metalloproteinase-2 and -9 in the ewe cervix during the estrous cycle.

    Science.gov (United States)

    Rodríguez-Piñón, M; Tasende, C; Casuriaga, D; Bielli, A; Genovese, P; Garófalo, E G

    2015-09-15

    The cervical collagen remodeling during the estrous cycle of the ewe was examined. The collagen concentration determined by a hydroxyproline assay and the area occupied by collagen fibers (%C), determined by van Gieson staining, were assessed in the cranial and caudal cervix of Corriedale ewes on Days 1 (n = 6), 6 (n = 5), or 13 (n = 6) after estrous detection (defined as Day 0). In addition, the gelatinase activity by in situ and SDS-PAGE gelatin zymographies and matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9, respectively) expression by immunohistochemistry were determined. The collagen concentration and %C were lowest on Day 1 of the estrous cycle (P MMP-2 activity was highest (P MMP-2 trend to be highest (P = 0.0819). The MMP-2 activity was detected in 73% of the homogenized cervical samples, and its expression was mainly detected in active fibroblasts. By contrast, the MMP-9 activity was detected in 9% of the samples, and its scarce expression was associated with plasmocytes, macrophages, and lymphocytes. Matrix metalloproteinase-2 expression was maximal on Day 1 in the cranial cervix and on Day 13 in the caudal cervix and was lower in the cranial than in the caudal cervix (P MMP-2 expression that differed between the cranial and caudal cervix may reflect their different physiological roles. The decrease in the collagen content and increase in fibroblast MMP-2 activity in sheep cervix on Day 1 of the estrous cycle suggests that cervical dilation at estrus is due to the occurrence of collagen fiber degradation modulated by changes in periovulatory hormone levels.

  6. Imaging Prostate Cancer Microenvironment by Collagen Hybridization

    Science.gov (United States)

    2015-10-01

    undergoing normal (e.g. skeleton) and pathological (arthritis) remodeling. 2. Demonstration of the use of CMP as collagen staining agent in SDS-PAGE gel...2. Demonstration of the CMP binding to mechanically damaged collagens (e.g. tendon injury). 3. Synthesis and in vivo targeting of polymer...engineering scaffolds, and diagnostic applications. 2. Demonstration of the CMP binding to mechanically damaged collagens (e.g. tendon injury

  7. Alginate-Collagen Fibril Composite Hydrogel.

    Science.gov (United States)

    Baniasadi, Mahmoud; Minary-Jolandan, Majid

    2015-02-16

    We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM)-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  8. Alginate-Collagen Fibril Composite Hydrogel

    Directory of Open Access Journals (Sweden)

    Mahmoud Baniasadi

    2015-02-01

    Full Text Available We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  9. Collagenous skeleton of the rat mystacial pad.

    Science.gov (United States)

    Haidarliu, Sebastian; Simony, Erez; Golomb, David; Ahissar, Ehud

    2011-05-01

    Anatomical and functional integrity of the rat mystacial pad (MP) is dependent on the intrinsic organization of its extracellular matrix. By using collagen autofluorescence, in the rat MP, we revealed a collagenous skeleton that interconnects whisker follicles, corium, and deep collagen layers. We suggest that this skeleton supports MP tissues, mediates force transmission from muscles to whiskers, facilitates whisker retraction after protraction, and limits MP extensibility.

  10. Stromal fibers in oral squamous cell carcinoma: A possible new prognostic indicator?

    Directory of Open Access Journals (Sweden)

    Priyanka Kardam

    2016-01-01

    Conclusion: The collagen fibers undergo a change in color, orientation and packing in the stroma of varying grades of OSCC. The uniqueness of this study lies in the exploration of elastic fibers in OSCC which has not been done so far.

  11. Understanding Collagen Organization in Breast Tumors to Predict and Prevent Metastasis

    Science.gov (United States)

    2015-11-01

    vessels in the skin arise from nestin-expressing hair - follicle cells. Proc Natl Acad Sci U S A. 2004; 101(36):13291–5. [PubMed: 15331785] 26. Koh... target . To take advantage of this, we must first learn the cellular players and molecular signals by which collagen ordering is induced. Therefore...establishing ordered fibers offers an exciting, and currently unexploited, therapeutic target . To take advantage of this, we must first learn the

  12. Artery buckling analysis using a two-layered wall model with collagen dispersion.

    Science.gov (United States)

    Mottahedi, Mohammad; Han, Hai-Chao

    2016-07-01

    Artery buckling has been proposed as a possible cause for artery tortuosity associated with various vascular diseases. Since microstructure of arterial wall changes with aging and diseases, it is essential to establish the relationship between microscopic wall structure and artery buckling behavior. The objective of this study was to developed arterial buckling equations to incorporate the two-layered wall structure with dispersed collagen fiber distribution. Seven porcine carotid arteries were tested for buckling to determine their critical buckling pressures at different axial stretch ratios. The mechanical properties of these intact arteries and their intima-media layer were determined via pressurized inflation test. Collagen alignment was measured from histological sections and modeled by a modified von-Mises distribution. Buckling equations were developed accordingly using microstructure-motivated strain energy function. Our results demonstrated that collagen fibers disperse around two mean orientations symmetrically to the circumferential direction (39.02°±3.04°) in the adventitia layer; while aligning closely in the circumferential direction (2.06°±3.88°) in the media layer. The microstructure based two-layered model with collagen fiber dispersion described the buckling behavior of arteries well with the model predicted critical pressures match well with the experimental measurement. Parametric studies showed that with increasing fiber dispersion parameter, the predicted critical buckling pressure increases. These results validate the microstructure-based model equations for artery buckling and set a base for further studies to predict the stability of arteries due to microstructural changes associated with vascular diseases and aging.

  13. Moving frames for heart fiber geometry

    DEFF Research Database (Denmark)

    Piuze, Emmanuel; Sporring, Jon; Siddiqi, Kaleem

    2013-01-01

    Elongated cardiac muscle cells named cardiomyocytes are densely packed in an intercellular collagen matrix and are aligned to helical segments in a manner which facilitates pumping via alternate contraction and relaxation. Characterizing the geometrical variation of their groupings as cardiac...... fibers is central to our understanding of normal heart function. Motivated by a recent abstraction by Savadjiev et al. of heart wall fibers into generalized helicoid minimal surfaces, this paper develops an extension based on differential forms. The key idea is to use Maurer-Cartan’s method of moving...

  14. Nanolayered Features of Collagen-like Peptides

    Science.gov (United States)

    Valluzzi, Regina; Bini, Elisabetta; Haas, Terry; Cebe, Peggy; Kaplan, David L.

    2003-01-01

    We have been investigating collagen-like model oligopeptides as molecular bases for complex ordered biomimetic materials. The collagen-like molecules incorporate aspects of native collagen sequence and secondary structure. Designed modifications to native primary and secondary structure have been incorporated to control the nanostructure and microstructure of the collagen-like materials produced. We find that the collagen-like molecules form a number of lyotropic rod liquid crystalline phases, which because of their strong temperature dependence in the liquid state can also be viewed as solvent intercalated thermotropic liquid crystals. The liquid crystalline phases formed by the molecules can be captured in the solid state by drying off solvent, resulting in solid nanopatterned (chemically and physically) thermally stable (to greater than 100 C) materials. Designed sequences which stabilize smectic phases have allowed a variety of nanoscale multilayered biopolymeric materials to be developed. Preliminary investigations suggest that chemical patterns running perpendicular to the smectic layer plane can be functionalized and used to localize a variety of organic, inorganic, and organometallic moieties in very simple multilayered nanocomposites. The phase behavior of collagen-like oligopeptide materials is described, emphasizing the correlation between mesophase, molecular orientation, and chemical patterning at the microscale and nanoscale. In many cases, the textures observed for smectic and hexatic phase collagens are remarkably similar to the complex (and not fully understood) helicoids observed in biological collagen-based tissues. Comparisons between biological morphologies and collagen model liquid crystalline (and solidified materials) textures may help us understand the molecular features which impart order and function to the extracellular matrix and to collagen-based mineralized tissues. Initial studies have utilized synthetic collagen-like peptides while

  15. Diode Pumped Fiber Laser.

    Science.gov (United States)

    1984-12-01

    FIBER LASERS I. Nd:YAG FIBER LASER FABRICATION .............. 5 A. FIBER GROWTH .......................... 5 B. FIBER PROCESSING 7...1.32 pm FIBER LASERS I. Nd:YAG FIBER LASER FABRICATION A. FIBER GROWTH The single crystal fibers used in this work were grown at Stanford University

  16. Modeling the coupled mechanics, transport, and growth processes in collagen tissues.

    Energy Technology Data Exchange (ETDEWEB)

    Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in' t Veld, Pieter J.; Stevens, Mark Jackson

    2006-11-01

    The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

  17. Swelling of Collagen-Hyaluronic Acid Co-Gels: An In Vitro Residual Stress Model.

    Science.gov (United States)

    Lai, Victor K; Nedrelow, David S; Lake, Spencer P; Kim, Bumjun; Weiss, Emily M; Tranquillo, Robert T; Barocas, Victor H

    2016-10-01

    Tissue-equivalents (TEs), simple model tissues with tunable properties, have been used to explore many features of biological soft tissues. Absent in most formulations however, is the residual stress that arises due to interactions among components with different unloaded levels of stress, which has an important functional role in many biological tissues. To create a pre-stressed model system, co-gels were fabricated from a combination of hyaluronic acid (HA) and reconstituted Type-I collagen (Col). When placed in solutions of varying osmolarity, HA-Col co-gels swell as the HA imbibes water, which in turn stretches (and stresses) the collagen network. In this way, co-gels with residual stress (i.e., collagen fibers in tension and HA in compression) were fabricated. When the three gel types tested here were immersed in hypotonic solutions, pure HA gels swelled the most, followed by HA-Col co-gels; no swelling was observed in pure collagen gels. The greatest swelling rates and swelling ratios occurred in the lowest salt concentration solutions. Tension on the collagen component of HA-Col co-gels was calculated from a stress balance and increased nonlinearly as swelling increased. The swelling experiment results were in good agreement with the stress predicted by a fibril network + non-fibrillar interstitial matrix computational model.

  18. Effect of venous wall immobilization on the thermal degradation of collagen

    Science.gov (United States)

    Ignat'eva, N. Yu.; Zakharkina, O. L.; Lunin, V. V.; Sergeeva, E. A.; Mazaishvili, K. V.; Maksimov, S. V.

    2013-11-01

    The results from a comparative study of the thermal denaturation of collagen in the venous walls of reference samples and samples with varicose disease are presented. Changes in the organization of collagen network of the tissue matrix are detected via thermal analysis and multiphoton microscopy with recording of the second harmonic generation (SHG). It is established that the collagen network of venous walls degrades in varicose disease. It is shown that the disordering of the tertiary structure of collagen molecules is reflected in a 40% drop in the enthalpy of protein denaturation compared to reference (Δ H D = 12.4 ± 4.9 J/g dry residue). The disorganization of fiber structures is recorded on SHG images. It is shown that upon the hydrothermal heating of sequestered samples of venous walls, the complete degradation of the tissue network occurs at 75°C. However, it is noted that upon the mechanical immobilization of samples of both types, the stability of collagen increases and complete denaturation is observed at temperatures above 84°C. It is suggested that the number of available conformations of polypeptide chains in the random coil state falls under tension, lowering Δ S D and raising the temperature of the denaturation of protein.

  19. Phase and Texture Characterizations of Scar Collagen Second-Harmonic Generation Images Varied with Scar Duration.

    Science.gov (United States)

    Chen, Guannan; Liu, Yao; Zhu, Xiaoqin; Huang, Zufang; Cai, Jianyong; Chen, Rong; Xiong, Shuyuan; Zeng, Haishan

    2015-08-01

    This work developed a phase congruency algorithm combined with texture analysis to quantitatively characterize collagen morphology in second-harmonic generation (SHG) images from human scars. The extracted phase and texture parameters of the SHG images quantified collagen directionality, homogeneity, and coarseness in scars and varied with scar duration. Phase parameters showed an increasing tendency of the mean of phase congruency with scar duration, indicating that collagen fibers are better oriented over time. Texture parameters calculated from local difference local binary pattern (LD-LBP) and Haar wavelet transform, demonstrated that the LD-LBP variance decreased and the energy of all subimages increased with scar duration. It implied that collagen has a more regular pattern and becomes coarser with scar duration. In addition, the random forest regression was used to predict scar duration, demonstrating reliable performance of the extracted phase and texture parameters in characterizing collagen morphology in scar SHG images. Results indicate that the extracted parameters using the proposed method can be used as quantitative indicators to monitor scar progression with time and can help understand the mechanism of scar progression.

  20. The Role of Type IV Collagen in Developing Lens in Mouse Fetuses

    Directory of Open Access Journals (Sweden)

    Mehdi Jalali

    2009-09-01

    Full Text Available Objective(sExtracellular matrix (ECM and basement membrane (BM play important roles in many developmental processes during development and after birth. Among the components of the BM, collagen fibers specially type IV are the most important parts. The aim of this study was to determine the time when collagen type IV appears in the BM of lens structure during mouse embryonic development.Materials and MethodsIn this experimental study, 22 female Balb/C mice were randomly selected and were kept under normal condition, finding vaginal plug was assumed as day zero of pregnancy. From embryonic day 10 to 20, all specimens were sacrificed by cervical dislocation and their heads were fixed, serially sectioned and immunohistochemistry study for tracing collagen type IV in lens were carried out.ResultsOur data revealed that collagen type IV appeared at the early stage of gestation day 12 in BM of anterior epithelial lens cells and the amount of this protein gradually increased until days 15-17 in ECM and posterior capsule epithelium. After this period, severe reaction was not observed in any part of the lens.ConclusionThese findings establish the important role of collagen IV in developing optic cup and any changes during critical period of pregnancy may be result in severe visual system defect

  1. Compósitos colágeno aniônico: fosfato de cálcio. Preparação e caracterização Collagen: calcium phosphate composites. Preparation and characterization

    Directory of Open Access Journals (Sweden)

    Marcos Roberto Bet

    1997-10-01

    Full Text Available Anionic collagen: calcium phosphate composite was obtained by controlled mixing of collagen and calcium phosphate until the consistence of a past. Material was characterized by a Ca/P ratio of 1.55, with a X-ray diffraction pattern similar to that for hydroxyapatite. Differential Scanning Calorimetry showed that the protein is not denatured under the processing conditions. Scanning Electronic Microscopy showed that the mineral phase are regularly covered with collagen fibers, indicating that anionic collagen is efficient in the preparation of stable form of calcium phosphate ceramic paste.

  2. Simultaneous observation of collagen and elastin based on the combined nonlinear optical imaging technique coupled with two-channel synchronized detection method

    Science.gov (United States)

    Chen, Jianxin; Zhuo, Shuangmu; Luo, Tianshu; Liu, Dingzhong; Zhao, Jingjun

    2008-08-01

    Collagen and elastin are the most important proteins of the connective tissues in higher vertebrates. In this paper, we present a combined nonlinear optical imaging technique of second-harmonic generation and two-photon excited fluorescence to simultaneously observe the collagen and elastic fiber of dermis in a freshly excised human skin and rabbit aorta using a two-channel synchronized detection method. The obtained two-channel overlay image in the backward direction can clearly distinguish the morphological structure and distribution of collagen and elastic fibers. Tissue spectrum further confirms the obtained structural information. These results suggest that the combined nonlinear optical imaging technique coupled with two-channel synchronized detection method can be an effective tool for detecting collage and elastic fibers without any invasive tissue procedure of slicing, embedding, fixation and staining when two structural proteins are simultaneously present in the biological tissue.

  3. Recombinant gelatin and collagen from methylotrophic yeasts

    NARCIS (Netherlands)

    Bruin, de E.C.

    2002-01-01

    Based on its structural role and compatibility within the human body, collagen is a commonly used biomaterial in medical applications, such as cosmetic surgery, wound treatment and tissue engineering. Gelatin is in essence denatured and partly degraded collagen and is, as a result of

  4. Imaging Prostate Cancer Microenvironment by Collagen Hybridization

    Science.gov (United States)

    2015-10-01

    collagen (type I) films ; (2) Validation of dual-labeled CMPs that display high affinity and specificity for stromal collagens in frozen PCa xenografts...signal with histopathology at prostatectomy for PSMA expression, Gleason score and other markers Aim 2: Synthesis of select PSMA-targeted imaging

  5. Pseudomembranous collagenous colitis with superimposed drug damage.

    Science.gov (United States)

    Villanacci, Vincenzo; Cristina, Silvia; Muscarà, Maurizio; Saettone, Silvia; Broglia, Laura; Antonelli, Elisabetta; Salemme, Marianna; Occhipinti, Pietro; Bassotti, Gabrio

    2013-11-01

    Pseudomembranous collagenous colitis is a rare pathological condition, not related to infectious agents, and characterized by thickening of the subepithelial collagen and formation of pseudomembranes. We report one such case, which responded to budesonide treatment after failures of previous approaches given, being unaware of the correct diagnosis.

  6. Thioamides in the collagen triple helix.

    Science.gov (United States)

    Newberry, Robert W; VanVeller, Brett; Raines, Ronald T

    2015-06-14

    To probe noncovalent interactions within the collagen triple helix, backbone amides were replaced with a thioamide isostere. This subtle substitution is the first in the collagen backbone that does not compromise thermostability. A triple helix with a thioamide as a hydrogen bond donor was found to be more stable than triple helices assembled from isomeric thiopeptides.

  7. Immunohistochemical localization of collagen VI in arthrofibrosis.

    Science.gov (United States)

    Zeichen, J; van Griensven, M; Albers, I; Lobenhoffer, P; Bosch, U

    1999-01-01

    Arthrofibrosis is a disabling complication after knee trauma and surgery. Clinically, it is characterized by pain and joint stiffness due to massive connective tissue proliferation. In similar pathological conditions with fibrotic transformation such as lung fibrosis or superficial fibromatoses, an increased expression of collagen type VI has been reported. Collagen VI, which forms a filamentous network, is thought to serve as an anchoring element between collagen I/III fibrils and basement membranes and as a cell binding structure. Collagen VI may also play a contributing role in the pathogenesis of arthrofibrosis. The aim of the present study was therefore to demonstrate the localization and distribution of type VI collagen in arthrofibrotic tissue. Tissue samples from the infrapatellar fat pad and intercondylar synovia of 13 patients suffering from arthrofibrosis were taken at surgery. The expression of type VI collagen was studied immunohistochemically using an immunoperoxidase method for light microscopic visualization. Histologic analysis showed a synovial hyperplasia with inflammatory cell infiltration and vascular proliferation. Compared with normal synovial tissue, type VI collagen was widely distributed as a network subsynovially and around the capillary walls. The results of the present study suggest that dysregulation of collagen VI synthesis could be an important contributing factor in the complex mechanisms of disordered matrix protein deposition leading to arthrofibrosis.

  8. Evaluation of chondrocyte growth in the highly porous scaffolds made by fused deposition manufacturing (FDM) filled with type II collagen.

    Science.gov (United States)

    Yen, Hung-Jen; Tseng, Ching-Shiow; Hsu, Shan-Hui; Tsai, Ching-Lin

    2009-06-01

    Highly porous poly(D,L-lactide-co-glycolide) (PLGA) scaffolds for cartilage tissue engineering were fabricated in this study using the fused deposition manufacturing (FDM) process and were further modified by type II collagen. The average molecular weight of PLGA decreased to about 60% of the original value after the melt-extrusion process. Type II collagen exhibited sponge-like structure and filled the macroporous FDM scaffolds. An increase of the fiber spacing resulted in an increase of the porosity. The storage modulus of FDM scaffolds with a large fiber spacing was comparable to that of the native porcine articular cartilage. Although the FDM hybrid scaffolds were swollen in various extents after 28 days of in vitro culture, the seeded chondrocytes were well distributed in the interior of the scaffolds with a large fiber spacing and neocartilage was formed around the scaffolds. The study also suggested that a low processing temperature may be required to produce PLGA precision scaffolds using FDM.

  9. Study of elastic system fibers in human gingiva

    Directory of Open Access Journals (Sweden)

    Walter Augusto Soares Machado

    Full Text Available Objective: To map the participation of the elastic system fibers of human gingiva. Methods: To conduct this study, fragments of human gingiva from ten individuals aged between 18 and 60 years, removed after periodontal surgery for prosthetic purposes, were analyzed by the histochemical and immuno-histochemical methods, to evaluate the participation of the elastic system fibers in this tissue. Results: The results demonstrated the presence of three type of elastic system fibers, that is to say, oxitalan, elaunin and elastic fibers,distributed as follows: 1 the oxitalan fibers form a network of thin fibers, located close to the basal membrane, at the level of the conjunctive tissue papillae; 2 elaunin fibers are found in close contact with the oxitalan fibers in the papillary and submaxillary regions, following the collagen fiber bundles; 3 a small quantity of elastic fibers were observed, dispersed throughout the deeper conjunctive tissue and around the blood vessels. Conclusion: The three types of elastic system fibers, that is, oxitalan, elaunin and elastic fibers are normal constituents of the extracellular matrixof human gingiva conjunctive tissue.

  10. Two Fiber Optical Fiber Thermometry

    Science.gov (United States)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  11. Influence of collagen source on fibrillar architecture and properties of vitrified collagen membranes.

    Science.gov (United States)

    Majumdar, Shoumyo; Guo, Qiongyu; Garza-Madrid, Marcos; Calderon-Colon, Xiomara; Duan, Derek; Carbajal, Priscilla; Schein, Oliver; Trexler, Morgana; Elisseeff, Jennifer

    2016-02-01

    Collagen vitrigel membranes are transparent biomaterials characterized by a densely organized, fibrillar nanostructure that show promise in the treatment of corneal injury and disease. In this study, the influence of different type I collagen sources and processing techniques, including acid-solubilized collagen from bovine dermis (Bov), pepsin-solubilized collagen from human fibroblast cell culture (HuCC), and ficin-solubilized collagen from recombinant human collagen expressed in tobacco leaves (rH), on the properties of the vitrigel membranes was evaluated. Postvitrification carbodiimide crosslinking (CX) was also carried out on the vitrigels from each collagen source, forming crosslinked counterparts BovXL, HuCCXL, and rHXL, respectively. Collagen membrane ultrastructure and biomaterial properties were found to rely heavily on both collagen source and crosslinking. Bov and HuCC samples showed a random fibrillar organization of collagen, whereas rH vitrigels showed remarkable regional fibril alignment. After CX, light transmission was enhanced in all groups. Denaturation temperatures after CX increased in all membranes, of which the highest increase was seen in rH (14.71°C), suggesting improved thermal stability of the collagen fibrils in the membranes. Noncrosslinked rH vitrigels may be reinforced through CX to reach levels of mechanical strength and thermal stability comparable to Bov.

  12. Molecular level detection and localization of mechanical damage in collagen enabled by collagen hybridizing peptides

    Science.gov (United States)

    Zitnay, Jared L.; Li, Yang; Qin, Zhao; San, Boi Hoa; Depalle, Baptiste; Reese, Shawn P.; Buehler, Markus J.; Yu, S. Michael; Weiss, Jeffrey A.

    2017-03-01

    Mechanical injury to connective tissue causes changes in collagen structure and material behaviour, but the role and mechanisms of molecular damage have not been established. In the case of mechanical subfailure damage, no apparent macroscale damage can be detected, yet this damage initiates and potentiates in pathological processes. Here, we utilize collagen hybridizing peptide (CHP), which binds unfolded collagen by triple helix formation, to detect molecular level subfailure damage to collagen in mechanically stretched rat tail tendon fascicle. Our results directly reveal that collagen triple helix unfolding occurs during tensile loading of collagenous tissues and thus is an important damage mechanism. Steered molecular dynamics simulations suggest that a likely mechanism for triple helix unfolding is intermolecular shearing of collagen α-chains. Our results elucidate a probable molecular failure mechanism associated with subfailure injuries, and demonstrate the potential of CHP targeting for diagnosis, treatment and monitoring of tissue disease and injury.

  13. A novel functional role of collagen glycosylation

    DEFF Research Database (Denmark)

    Jürgensen, Henrik J; Madsen, Daniel H; Ingvarsen, Signe

    2011-01-01

    , the function of which is poorly known. The endocytic collagen receptor urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180 plays an important role in matrix remodeling through its ability to internalize collagen for lysosomal degradation. uPARAP/Endo180 is a member of the mannose...... receptor protein family. These proteins all include a fibronectin type II domain and a series of C-type lectin-like domains, of which only a minor part possess carbohydrate recognition activity. At least two of the family members, uPARAP/Endo180 and the mannose receptor, interact with collagens....... By expressing truncated recombinant uPARAP/Endo180 proteins and analyzing their interaction with collagens with high and low levels of glycosylation we demonstrated that this lectin domain interacts directly with glycosylated collagens. This interaction is functionally important because it was found to modulate...

  14. Bioengineered collagens: emerging directions for biomedical materials.

    Science.gov (United States)

    Ramshaw, John A M; Werkmeister, Jerome A; Dumsday, Geoff J

    2014-01-01

    Mammalian collagen has been widely used as a biomedical material. Nevertheless, there are still concerns about the variability between preparations, particularly with the possibility that the products may transmit animal-based diseases. Many groups have examined the possible application of bioengineered mammalian collagens. However, translating laboratory studies into large-scale manufacturing has often proved difficult, although certain yeast and plant systems seem effective. Production of full-length mammalian collagens, with the required secondary modification to give proline hydroxylation, has proved difficult in E. coli. However, recently, a new group of collagens, which have the characteristic triple helical structure of collagen, has been identified in bacteria. These proteins are stable without the need for hydroxyproline and are able to be produced and purified from E. coli in high yield. Initial studies indicate that they would be suitable for biomedical applications.

  15. Anterior cruciate ligament: 3-D fiber anatomy, fluorescence arthroscopy & healing

    NARCIS (Netherlands)

    Nguyen, D.T.

    2015-01-01

    One of the current emphases in optimizing anterior cruciate ligament (ACL) reconstructions is closer mimicking the anatomy of the ACL. The aim of Chapter 2 and Chapter 3 is to develop and validate a methodology to quantify the 3-D collagen fiber orientation of ligaments, accurately and at a high res

  16. Vacuum fiber-fiber coupler

    Science.gov (United States)

    Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe

    2017-02-01

    Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.

  17. Glaucoma-related Changes in the Mechanical Properties and Collagen Micro-architecture of the Human Sclera.

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    Baptiste Coudrillier

    Full Text Available The biomechanical behavior of the sclera determines the level of mechanical insult from intraocular pressure to the axons and tissues of the optic nerve head, as is of interest in glaucoma. In this study, we measure the collagen fiber structure and the strain response, and estimate the material properties of glaucomatous and normal human donor scleras.Twenty-two posterior scleras from normal and diagnosed glaucoma donors were obtained from an eyebank. Optic nerve cross-sections were graded to determine the presence of axon loss. The specimens were subjected to pressure-controlled inflation testing. Full-field displacement maps were measured by digital image correlation (DIC and spatially differentiated to compute surface strains. Maps of the collagen fiber structure across the posterior sclera of each inflated specimen were obtained using synchrotron wide-angle X-ray scattering (WAXS. Finite element (FE models of the posterior scleras, incorporating a specimen-specific representation of the collagen structure, were constructed from the DIC-measured geometry. An inverse finite element analysis was developed to estimate the stiffness of the collagen fiber and inter-fiber matrix.The differences between glaucoma and non-glaucoma eyes were small in magnitude. Sectorial variations of degree of fiber alignment and peripapillary scleral strain significantly differed between normal and diagnosed glaucoma specimens. Meridional strains were on average larger in diagnosed glaucoma eyes compared with normal specimens. Non-glaucoma specimens had on average the lowest matrix and fiber stiffness, followed by undamaged glaucoma eyes, and damaged glaucoma eyes but the differences in stiffness were not significant.The observed biomechanical and microstructural changes could be the result of tissue remodeling occuring in glaucoma and are likely to alter the mechanical environment of the optic nerve head and contribute to axonal damage.

  18. In-situ Damage Assessment of Collagen within Ancient Manuscripts Written on Parchment: A Polarized Raman Spectroscopy Approach

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    Schütz, R.; Rabin, I.; Hahn, O.; Fratzl, P.; Masic, A.

    2010-08-01

    The collection generally known as Qumran scrolls or Dead Sea Scrolls (DSS) comprises some 900 highly fragmented manuscripts (mainly written on parchment) from the Second Temple period. In the years since their manufacture the writing materials have undergone serious deterioration due to a combination of natural ageing and environmental effects. Therefore, understanding quantitatively state of conservation of such manuscripts is a challenging task and a deep knowledge of damage pathways on all hierarchical levels (from molecular up to macroscopic) results of fundamental importance for a correct protection and conservation strategy. However, the degradation of parchments is very complex and not well understood process. Parchment is a final product of processing of animal skin and consist mainly of type I collagen, which is the most abundant constituent of the dermal matrix. Collagen molecule is built by folding of three polypeptide α-chains into a right-handed triple helix. Every α-chain is made by a repetitive sequence of (Gly-X-Y)n, where X and Y are often proline and hydroxyproline. Parallel and staggered collagen triple helices associate into fibrils, which than assemble into fibers. Deterioration of parchment is caused by chemical changes due to gelatinization, oxidation and hydrolysis of the collagen chains, promoted by several factors, summarized as biological and microbiological (bacteria, fungi etc.), heat, light, humidity and pollutants (1, 2). In this work we have focused on studying the collagen within parchments on two different levels of organization (molecular and fibrilar) by applying polarized Raman spectroscopic technique. Beside spectral information related to chemical bonding, polarization anisotropy of some collagen bands (i.e. amide I) has been used to explore organization of collagen on higher levels (three-dimensional arrangement of the triple-helix molecules and their alignment within a fibril of collagen). To this aim we have compared

  19. Molecular transport in collagenous tissues measured by gel electrophoresis.

    Science.gov (United States)

    Hunckler, Michael D; Tilley, Jennifer M R; Roeder, Ryan K

    2015-11-26

    Molecular transport in tissues is important for drug delivery, nutrient supply, waste removal, cell signaling, and detecting tissue degeneration. Therefore, the objective of this study was to investigate gel electrophoresis as a simple method to measure molecular transport in collagenous tissues. The electrophoretic mobility of charged molecules in tissue samples was measured from relative differences in the velocity of a cationic dye passing through an agarose gel in the absence and presence of a tissue section embedded within the gel. Differences in electrophoretic mobility were measured for the transport of a molecule through different tissues and tissue anisotropy, or the transport of different sized molecules through the same tissue. Tissue samples included tendon and fibrocartilage from the proximal (tensile) and distal (compressive) regions of the bovine flexor tendon, respectively, and bovine articular cartilage. The measured electrophoretic mobility was greatest in the compressive region of the tendon (fibrocartilage), followed by the tensile region of tendon, and lowest in articular cartilage, reflecting differences in the composition and organization of the tissues. The anisotropy of tendon was measured by greater electrophoretic mobility parallel compared with perpendicular to the predominate collagen fiber orientation. Electrophoretic mobility also decreased with increased molecular size, as expected. Therefore, the results of this study suggest that gel electrophoresis may be a useful method to measure differences in molecular transport within various tissues, including the effects of tissue type, tissue anisotropy, and molecular size. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. In situ visualization of dermal collagen dynamics during skin burn healing using second-harmonic-generation microscopy

    Science.gov (United States)

    Yasui, Takeshi; Hase, Eiji; Tanaka, Ryosuke; Fukushima, Shu-ichiro; Araki, Tsutomu

    2015-06-01

    Burn healing is a process to repair thermally damaged tissues. Although burn healing has many aspects, it is common for dynamics of collagen fiber, such as decomposition, production, or growth, to be closely related with burn healing. If such healing process can be visualized from the viewpoint of the collagen dynamics, one may obtain new findings regarding biological repairing mechanisms in the healing process. To this end, second-harmonic-generation (SHG) light will be an effective optical probe because of high selectivity and good image contrast to collagen molecules as well as high spatial resolution, optical three-dimensional (3D) sectioning, minimal invasiveness, deep penetration, the absence of interference from background light, and in situ measurement without additional staining. Furthermore, since SHG light arises from a non-centrosymmetric triple helix of three polypeptide chains in the collagen molecule, its intensity decreases and finally disappears when thermal denaturation caused by the skin burn changes the structure of this molecule to a centrosymmetric random coil. Therefore, optical assessment of skin burn has been investigated by SHG microscopy. In this paper, we applied SHG microscopy for in situ imaging of the healing process in animal skin burn and successfully visualized the decomposition, production, and growth of renewal collagen fibers as a series of time-lapse images in the same subject.

  1. In situ quantitative evaluation of osteoblastic collagen synthesis under cyclic strain by using second-harmonic-generation microscope

    Science.gov (United States)

    Matsubara, Oki; Hase, Eiji; Minamikawa, Takeo; Yasui, Takeshi; Sato, Katsuya

    2016-03-01

    Osteoblast-produced collagen matrix in bone is influenced by the mechanical stimulus from their surroundings. However, it has been still unclear how mechanical stimulus affects collagen production by osteoblasts. Therefore, it is strongly required to investigate the characteristics of osteoblastic bone regenerative tissue engineering. Recently, second-harmonic-generation (SHG) microscope has attracted attention for in situ visualization of collagen fiber because of less invasiveness, unstaining and no fixation, as well as high spatial resolution and 3D imaging. Using SHG microscopy, one can track the temporal dynamics of collagen fiber during the cultured period of the sample. We applied cyclic stretch strain to osteoblasts (MC3T3-E1) by using originally developed cell stretching device. The stimulation time was set to 5min or 3hours with same strain 5% and same frequency 0.5Hz. Cells were seeded onto the PDMS (polydimethylsiloxane) rubber chamber at a density of 50,000 cells/cm2 and cultured in α-MEM with 10% FBS, 1% P/S, 1% Ascorbic acid, 0.2% hydrocortisone and 2% β-Glycerophosphate. SHG imaging was carried out every 7 days. As a result, we confirmed from SHG image that the collagen production was enhanced by the cyclic stretch strain, stretch stimulation time and stretch application term.

  2. Collagen immobilization of multi-layered BCP-ZrO{sub 2} bone substitutes to enhance bone formation

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    Linh, Nguyen Thuy Ba [Department of Regenerative Medicine, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Institute of Tissue Regeneration, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Jang, Dong-Woo [Department of Regenerative Medicine, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Lee, Byong-Taek, E-mail: lbt@sch.ac.kr [Department of Regenerative Medicine, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Institute of Tissue Regeneration, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of)

    2015-08-01

    Graphical abstract: - Highlights: • Col-BCP-ZrO. • Collagen fibers were formed and attached firmly on the surface of BCP-ZrO. • Highly interconnected but uniform porosity were obtained. • High biocompatible, strength scaffolds and new bone were evident in Col-BCP-ZrO{sub 2}. - Abstract: A porous microstructure of multi-layered BCP-ZrO{sub 2} bone substitutes was fabricated using the sponge replica method in which the highly interconnected structure was immobilized with collagen via ethyl(dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide crosslinking. Their struts are combined with a three-layered BCP/BCP-ZrO{sub 2}/ZrO{sub 2} microstructure. Collagen fibers were firmly attached to the strut surface of the BCP-ZrO{sub 2} scaffolds. With control of the three-layered microstructure and collagen immobilization, the compressive strength of the scaffolds increased significantly to 6.8 MPa compared to that of the monolithic BCP scaffolds (1.3 MPa). An in vitro study using MTT, confocal observation, and real-time polymer chain reaction analysis demonstrated that the proliferation and differentiation of the pre-osteoblast-like MC3T3-E1 cells was improved due to the collagen incorporation. Remarkable enhancement of bone regeneration was observed without any immunological reaction in the femurs of rabbits during 1 and 5 months of implantation. Furthermore, the interfaces between new bone and the scaffold struts bonded directly without any gaps.

  3. Stereological study of collagen and elastic system in the detrusor muscle of bladders from controls and patients with infravesical obstruction

    Directory of Open Access Journals (Sweden)

    Mauricio Rubinstein

    2007-02-01

    Full Text Available OBJECTIVE: Compare detrusor muscle of normal and patients with infravesical obstruction, quantifying the collagen and elastic system fibers. MATERIALS AND METHODS: We studied samples taken from bladders of 10 patients whose ages ranged from 45 to 75 years (mean = 60 years, who underwent transvesical prostatectomy for treatment of BPH. Control material was composed of 10 vesical specimens, removed during autopsies performed in cadavers of accident victims, with ages between 18 and 35 years (mean = 26 years. RESULTS: The results of collagen and elastic fibers quantification (volumetric density demonstrated the following results in percentage (mean +/- standard deviation: collagen in BPH patients = 4.89 +/- 2.64 and 2.32 +/- 1.25 in controls (p < 0.0001, elastin in BPH patients = 10.63% +/- 2.00 and 8.94% +/- 1.19 in controls (p < 0.0001. CONCLUSION: We found that the components of connective tissue, collagen and elastic system fibers are increased in the detrusor muscle of patients with infravesical obstruction, when compared to controls.

  4. Sciatic nerve regeneration in rats by a promising electrospun collagen/poly(ε-caprolactone nerve conduit with tailored degradation rate

    Directory of Open Access Journals (Sweden)

    Jiang Xinquan

    2011-07-01

    Full Text Available Abstract Background To cope with the limitations faced by autograft acquisitions particularly for multiple nerve injuries, artificial nerve conduit has been introduced by researchers as a substitute for autologous nerve graft for the easy specification and availability for mass production. In order to best mimic the structures and components of autologous nerve, great efforts have been made to improve the designation of nerve conduits either from materials or fabrication techniques. Electrospinning is an easy and versatile technique that has recently been used to fabricate fibrous tissue-engineered scaffolds which have great similarity to the extracellular matrix on fiber structure. Results In this study we fabricated a collagen/poly(ε-caprolactone (collagen/PCL fibrous scaffold by electrospinning and explored its application as nerve guide substrate or conduit in vitro and in vivo. Material characterizations showed this electrospun composite material which was made of submicron fibers possessed good hydrophilicity and flexibility. In vitro study indicated electrospun collagen/PCL fibrous meshes promoted Schwann cell adhesion, elongation and proliferation. In vivo test showed electrospun collagen/PCL porous nerve conduits successfully supported nerve regeneration through an 8 mm sciatic nerve gap in adult rats, achieving similar electrophysiological and muscle reinnervation results as autografts. Although regenerated nerve fibers were still in a pre-mature stage 4 months postoperatively, the implanted collagen/PCL nerve conduits facilitated more axons regenerating through the conduit lumen and gradually degraded which well matched the nerve regeneration rate. Conclusions All the results demonstrated this collagen/PCL nerve conduit with tailored degradation rate fabricated by electrospinning could be an efficient alternative to autograft for peripheral nerve regeneration research. Due to its advantage of high surface area for cell attachment, it

  5. Oxytalan elastic and collagen fibers during the repair process in experimental nitric oxide inhibition Fibras elásticas oxitalânicas e fibras colágenas durante o processo de reparo na inibição experimental do óxido nítrico

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    Ricardo Xavier-Vidal

    2005-04-01

    Full Text Available PURPOSE: To evaluate the repair process in rats with experimentally induced arterial hypertension. This study aimed to evaluate lesions in the ventricular myocardium and the repair process during experimental hypertension induced by systemic blockage of nitric oxide using N-omega-nitro-L-arginine methyl ester hydrochloride (L-NAME. Nitric oxide is an endothelial vasorelaxing factor and is necessary for the maintenance of normal arterial pressure, and L-NAME is an analog and antagonist of L-arginine, the substrate of the nitric oxide synthase. MATERIALS AND METHODS: We used 26 normotensive young male Wistar rats belonging to several litters. Animals were treated with oral administration of L-NAME dissolved in water (75 mg/100 mL for 43 days . Hearts were weighed and processed by routine methods. Special stains utilized were Gomori's trichrome (aniline blue, picrosirius red polarization to identify fibrillar collagen, alcian blue technique (pH 0.5 and pH 2.5 to identify glycosaminoglycans, periodic acid-Schiff technique (with and without amylases to identify proteoglycans, and Weigert's resorcinol fuchsin solution (with and without oxone to identify elastic fibers. RESULTS: The results showed significant elevation of the arterial pressure (P OBJETIVO: Avaliar o processo de reparo em ratos submetidos à hipertensão arterial experimental. Avaliamos lesões miocárdicas ventriculares e processos de reparo durante a hipertensão arterial experimental induzida pelo bloqueio da síntese do óxido nítrico (ON utilizando o Hidrocloreto de L-NAME. ON é um fator de relaxamento endotelial e é necessário para a manutenção da pressão arterial normal. L-NAME é um analogo e antagonista da L-Arginine que é o substrato da enzima óxido nítrico sintase. MATERIAL E MÉTODOS: Utilizamos 26 ratos Wistar normotensos jovens oriundos de diversas ninhadas. Os animais foram submetidos ao L-NAME (Hidrocloreto de Nw-nitro-L-arginina metil ester por administra

  6. Dietary fiber.

    Science.gov (United States)

    Madar, Z; Thorne, R

    1987-01-01

    Studies done on dietary fiber (DF) over the past five years are presented in this Review. The involvement of dietary fiber in the control of plasma glucose and lipid levels is now established. Two dietary fiber sources (soybean and fenugreek) were studied in our laboratory and are discussed herein. These sources were found to be potentially beneficial in the reduction of plasma glucose in non-insulin dependent diabetes mellitus subjects. They are shown to be acceptable by human subjects and are easy to use either in a mixture of milk products and in cooking. The mechanism by which dietary fiber alters the nutrient absorption is also discussed. The effect of DF on gastric emptying, transit time, adsorption and glucose transport may contribute to reducing plasma glucose and lipid levels. DF was found to be effective in controlling blood glucose and lipid levels of pregnant diabetic women. Dietary fiber may also be potentially beneficial in the reduction of exogenous insulin requirements in these subjects. However, increased consumption of DF may cause adverse side effects; the binding capabilities of fiber may affect nutrient availability, particularly that of minerals and prolonged and high DF dosage supplementation must be regarded cautiously. This is particularly true when recommending such a diet for pregnant or lactating women, children or subjects with nutritional disorders. Physiological effects of DF appear to depend heavily on the source and composition of fiber. Using a combination of DF from a variety of sources may reduce the actual mass of fiber required to obtain the desired metabolic effects and will result in a more palatable diet. Previously observed problems, such as excess flatus, diarrhea and mineral malabsorption would also be minimized.

  7. Nonlinear optical response of the collagen triple helix and second harmonic microscopy of collagen liquid crystals

    Science.gov (United States)

    Deniset-Besseau, A.; De Sa Peixoto, P.; Duboisset, J.; Loison, C.; Hache, F.; Benichou, E.; Brevet, P.-F.; Mosser, G.; Schanne-Klein, M.-C.

    2010-02-01

    Collagen is characterized by triple helical domains and plays a central role in the formation of fibrillar and microfibrillar networks, basement membranes, as well as other structures of the connective tissue. Remarkably, fibrillar collagen exhibits efficient Second Harmonic Generation (SHG) and SHG microscopy proved to be a sensitive tool to score fibrotic pathologies. However, the nonlinear optical response of fibrillar collagen is not fully characterized yet and quantitative data are required to further process SHG images. We therefore performed Hyper-Rayleigh Scattering (HRS) experiments and measured a second order hyperpolarisability of 1.25 10-27 esu for rat-tail type I collagen. This value is surprisingly large considering that collagen presents no strong harmonophore in its amino-acid sequence. In order to get insight into the physical origin of this nonlinear process, we performed HRS measurements after denaturation of the collagen triple helix and for a collagen-like short model peptide [(Pro-Pro-Gly)10]3. It showed that the collagen large nonlinear response originates in the tight alignment of a large number of weakly efficient harmonophores, presumably the peptide bonds, resulting in a coherent amplification of the nonlinear signal along the triple helix. To illustrate this mechanism, we successfully recorded SHG images in collagen liquid solutions by achieving liquid crystalline ordering of the collagen triple helices.

  8. Age Increases Monocyte Adhesion on Collagen

    Science.gov (United States)

    Khalaji, Samira; Zondler, Lisa; Kleinjan, Fenneke; Nolte, Ulla; Mulaw, Medhanie A.; Danzer, Karin M.; Weishaupt, Jochen H.; Gottschalk, Kay-E.

    2017-05-01

    Adhesion of monocytes to micro-injuries on arterial walls is an important early step in the occurrence and development of degenerative atherosclerotic lesions. At these injuries, collagen is exposed to the blood stream. We are interested whether age influences monocyte adhesion to collagen under flow, and hence influences the susceptibility to arteriosclerotic lesions. Therefore, we studied adhesion and rolling of human peripheral blood monocytes from old and young individuals on collagen type I coated surface under shear flow. We find that firm adhesion of monocytes to collagen type I is elevated in old individuals. Pre-stimulation by lipopolysaccharide increases the firm adhesion of monocytes homogeneously in older individuals, but heterogeneously in young individuals. Blocking integrin αx showed that adhesion of monocytes to collagen type I is specific to the main collagen binding integrin αxβ2. Surprisingly, we find no significant age-dependent difference in gene expression of integrin αx or integrin β2. However, if all integrins are activated from the outside, no differences exist between the age groups. Altered integrin activation therefore causes the increased adhesion. Our results show that the basal increase in integrin activation in monocytes from old individuals increases monocyte adhesion to collagen and therefore the risk for arteriosclerotic plaques.

  9. Molecular structure of the collagen triple helix.

    Science.gov (United States)

    Brodsky, Barbara; Persikov, Anton V

    2005-01-01

    The molecular conformation of the collagen triple helix confers strict amino acid sequence constraints, requiring a (Gly-X-Y)(n) repeating pattern and a high content of imino acids. The increasing family of collagens and proteins with collagenous domains shows the collagen triple helix to be a basic motif adaptable to a range of proteins and functions. Its rodlike domain has the potential for various modes of self-association and the capacity to bind receptors, other proteins, GAGs, and nucleic acids. High-resolution crystal structures obtained for collagen model peptides confirm the supercoiled triple helix conformation, and provide new information on hydrogen bonding patterns, hydration, sidechain interactions, and ligand binding. For several peptides, the helix twist was found to be sequence dependent, and such variation in helix twist may serve as recognition features or to orient the triple helix for binding. Mutations in the collagen triple-helix domain lead to a variety of human disorders. The most common mutations are single-base substitutions that lead to the replacement of one Gly residue, breaking the Gly-X-Y repeating pattern. A single Gly substitution destabilizes the triple helix through a local disruption in hydrogen bonding and produces a discontinuity in the register of the helix. Molecular information about the collagen triple helix and the effect of mutations will lead to a better understanding of function and pathology.

  10. Probing interactions between collagen proteins via microrheology

    Science.gov (United States)

    Shayegan, Marjan; Forde, Nancy R.

    2012-10-01

    Collagen is the major structural protein of our connective tissues. It provides integrity and mechanical strength through its hierarchical organization. Defects in collagen can lead to serious connective tissue diseases. Collagen is also widely used as a biomaterial. Given that mechanical properties are related to the structure of materials, the main goal of our research is to understand how molecular structure correlates with microscale mechanical properties of collagen solutions and networks. We use optical tweezers to trap and monitor thermal fluctuations of an embedded probe particle, from which viscoelastic properties of the solution are extracted. We find that elasticity becomes comparable to viscous behavior at collagen concentrations of 5mg/ml. Furthermore, by simultaneously neutralizing pH and adding salt, we observe changes in viscosity and elasticity of the solution over time. We attribute this to the self-assembly process of collagen molecules into fibrils with different mechanical properties. Self-assembly of collagen under these conditions is verified by turbidity measurements as well as electron microscopy. By comparing results from these local studies of viscoelasticity, we can detect spatial heterogeneity of fibril formation throughout the solution.

  11. Image analyses of collagen types and thickness in oral sub mucous fibrosis stained with picrosirius red under polarizing microscope

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    Venkatesh V Kamath

    2013-01-01

    Full Text Available Context: Oral submucous fibrosis (OSF is a potentially malignant oral disorder leading to increased fibrosis in the sub-epithelial layer. The collagen in the condition has been a subject of intense scrutiny in an attempt to understand the pathogenesis of the disease. Aim: The present study aims to quantify and qualify the collagen fibers in different histological grades of OSF using picrosirius red stain under the polarizing microscope. The quantification of the fibrosis was carried out using image analysis software and the fibers were graded according to staining hue and intensity into their respective subtypes. Comparison was done with normal mucosa, scar/keloid tissue samples. Materials and Methods: The present study included OSF (n = 50 of differing histological grades, keloid/scar (n = 4 and normal mucosa (n = 6 as control cases. Histological assessment was performed on hematoxylin and eosin stained sections. Picrosirius red stained slides were observed under a polarizing microscope for assessment of collagen subtypes. Quantification of collagen was done under polarizing microscope and image parameters were analyzed using ProReg® Capture Pro 2.8.8 (Lawrence and Mayo India Pvt Ltd, 2011 image analysis software. Results: The epithelial thickness in OSF, scar and keloid is less than that of normal mucosa and progressive decrease in the epithelial thickness is seen in the successive stages of OSF. The fibrosis increases with increasing grades of OSF, was higher in scar and keloid and was highly statistically significant. Type I collagen was more predominant in all stages of OSF, in normal oral mucosa and scar/keloid tissue samples as compared with type III. Though quantitative analysis of the collagen types I and III is possible, with picrosirius red qualitative analysis is an arduous task. The specificity of detection of collagen subtypes was acceptable with the picrosirius red stain, but the sensitivity left a lot to be desired.

  12. Characterization of genipin-modified dentin collagen.

    Science.gov (United States)

    Nagaoka, Hiroko; Nagaoka, Hideaki; Walter, Ricardo; Boushell, Lee W; Miguez, Patricia A; Burton, Andrew; Ritter, André V; Yamauchi, Mitsuo

    2014-01-01

    Application of biomodification techniques to dentin can improve its biochemical and biomechanical properties. Several collagen cross-linking agents have been reported to strengthen the mechanical properties of dentin. However, the characteristics of collagen that has undergone agent-induced biomodification are not well understood. The objective of this study was to analyze the effects of a natural cross-linking agent, genipin (GE), on dentin discoloration, collagen stability, and changes in amino acid composition and lysyl oxidase mediated natural collagen cross-links. Dentin collagen obtained from extracted bovine teeth was treated with three different concentrations of GE (0.01%, 0.1%, and 0.5%) for several treatment times (0-24 h). Changes in biochemical properties of NaB(3)H4-reduced collagen were characterized by amino acid and cross-link analyses. The treatment of dentin collagen with GE resulted in a concentration- and time-dependent pigmentation and stability against bacterial collagenase. The lysyl oxidase-mediated trivalent mature cross-link, pyridinoline, showed no difference among all groups while the major divalent immature cross-link, dehydro-dihydroxylysinonorleucine/its ketoamine in collagen treated with 0.5% GE for 24 h, significantly decreased compared to control (P < 0.05). The newly formed GE-induced cross-links most likely involve lysine and hydroxylysine residues of collagen in a concentration-dependent manner. Some of these cross-links appear to be reducible and stabilized with NaB(3)H4.

  13. Characterization of Genipin-Modified Dentin Collagen

    Directory of Open Access Journals (Sweden)

    Hiroko Nagaoka

    2014-01-01

    Full Text Available Application of biomodification techniques to dentin can improve its biochemical and biomechanical properties. Several collagen cross-linking agents have been reported to strengthen the mechanical properties of dentin. However, the characteristics of collagen that has undergone agent-induced biomodification are not well understood. The objective of this study was to analyze the effects of a natural cross-linking agent, genipin (GE, on dentin discoloration, collagen stability, and changes in amino acid composition and lysyl oxidase mediated natural collagen cross-links. Dentin collagen obtained from extracted bovine teeth was treated with three different concentrations of GE (0.01%, 0.1%, and 0.5% for several treatment times (0–24 h. Changes in biochemical properties of NaB3H4-reduced collagen were characterized by amino acid and cross-link analyses. The treatment of dentin collagen with GE resulted in a concentration- and time-dependent pigmentation and stability against bacterial collagenase. The lysyl oxidase-mediated trivalent mature cross-link, pyridinoline, showed no difference among all groups while the major divalent immature cross-link, dehydro-dihydroxylysinonorleucine/its ketoamine in collagen treated with 0.5% GE for 24 h, significantly decreased compared to control (P< 0.05. The newly formed GE-induced cross-links most likely involve lysine and hydroxylysine residues of collagen in a concentration-dependent manner. Some of these cross-links appear to be reducible and stabilized with NaB3H4.

  14. Sequence dependence of kinetics and morphology of collagen model peptide self-assembly into higher order structures

    OpenAIRE

    Kar, Karunakar; Wang, Yuh-Hwa; Brodsky, Barbara

    2008-01-01

    The process of self-assembly of the triple-helical peptide (Pro-Hyp-Gly)10 into higher order structure resembles the nucleation-growth mechanism of collagen fibril formation in many features, but the irregular morphology of the self-assembled peptide contrasts with the ordered fibers and networks formed by collagen in vivo. The amino acid sequence in the central region of the (Pro-Hyp-Gly)10 peptide was varied and found to affect the kinetics of self-assembly and nature of the higher order st...

  15. Collagen-biomorphic porous carbon nanofiber monoliths: Biosilicification-assisted sustainable synthesis and application in Li-S battery

    Science.gov (United States)

    Hu, Wen; Shen, Tao; Hou, Hongying; Gan, Guoyou; Zheng, Biju; Li, Fengxian; Yi, Jianhong

    2016-12-01

    Monolithic carbon has been synthesized via a sustainable biomimetic route utilizing intrafibrillar silicified collagen sponge as precursor and morphogenesis template. The mineralized silica in the biohybrid prevents collapse of the carbon during pyrolysis. Upon biosilica removal results show that the carbon monoliths inherit the porous fiber structure of the mother collagen. The carbon nanofiber framework facilitates the construction of a high electrical conductive pathway, while the internal spaces developed among the intertwined fibrillar network and pores within nanofiber walls offer room for sulfur storage. The as-obtained carbon-sulfur cathode exhibits an accessible discharge capacity approaching 800mAh g-1 in Li-S battery.

  16. Fourier transform infrared spectroscopy to quantify collagen and elastin in an in vitro model of extracellular matrix degradation in aorta.

    Science.gov (United States)

    Cheheltani, Rabee; McGoverin, Cushla M; Rao, Jayashree; Vorp, David A; Kiani, Mohammad F; Pleshko, Nancy

    2014-06-21

    Extracellular matrix (ECM) is a key component and regulator of many biological tissues including aorta. Several aortic pathologies are associated with significant changes in the composition of the matrix, especially in the content, quality and type of aortic structural proteins, collagen and elastin. The purpose of this study was to develop an infrared spectroscopic methodology that is comparable to biochemical assays to quantify collagen and elastin in aorta. Enzymatically degraded porcine aorta samples were used as a model of ECM degradation in abdominal aortic aneurysm (AAA). After enzymatic treatment, Fourier transform infrared (FTIR) spectra of the aortic tissue were acquired by an infrared fiber optic probe (IFOP) and FTIR imaging spectroscopy (FT-IRIS). Collagen and elastin content were quantified biochemically and partial least squares (PLS) models were developed to predict collagen and elastin content in aorta based on FTIR spectra. PLS models developed from FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (RMSE of validation = 8.4% and 11.1% of the range respectively), and IFOP spectra were successfully used to predict elastin content (RMSE = 11.3% of the range). The PLS regression coefficients from the FT-IRIS models were used to map collagen and elastin in tissue sections of degraded porcine aortic tissue as well as a human AAA biopsy tissue, creating a similar map of each component compared to histology. These results support further application of FTIR spectroscopic techniques for evaluation of AAA tissues.

  17. Characterization of type I, II, III, IV, and V collagens by time-resolved laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Marcu, Laura; Cohen, David; Maarek, Jean-Michel I.; Grundfest, Warren S.

    2000-04-01

    The relative proportions of genetically distinct collagen types in connective tissues vary with tissue type and change during disease progression, development, wound healing, aging. This study aims to 1) characterize the spectro- temporal fluorescence emission of fiber different types of collagen and 2) assess the ability of time-resolved laser- induced fluorescence spectroscopy to distinguish between collagen types. Fluorescence emission of commercially available purified samples was induced with nitrogen laser excitation pulses and detected with a MCP-PMT connected to a digital storage oscilloscope. The recorded time-resolved emission spectra displayed distinct fluorescence emission characteristics for each collagen type. The time domain information complemented the spectral domain intensity data for improved discrimination between different collagen types. Our results reveal that analysis of the fluorescence emission can be used to characterize different species of collagen. Also, the results suggest that time-resolved spectroscopy can be used for monitoring of connective tissue matrix composition changes due to various pathological and non-pathological conditions.

  18. Lamination of microfibrous PLGA fabric by electrospinning a layer of collagen-hydroxyapatite composite nanofibers for bone tissue engineering.

    Science.gov (United States)

    Kwon, Gi-Wan; Gupta, Kailash Chandra; Jung, Kyung-Hye; Kang, Inn-Kyu

    2017-01-01

    To mimic the muscle inspired cells adhesion through proteins secretion, the lamination of collagen-hydroxyapatite nanorod (nHA) composite nanofibers has been carried out successfully on polydopamine (PDA)-coated microfibrous polylactide-co-glycolide (PLGA) fabrics. The lamination of collagen-hydroxyapatite composite nanofibers on polydopamine-coated microfibrous PLGA fabrics was carried through electrospinning the solution of collagen containing L-glutamic acid-grafted hydroxyapatite nanorods (nHA-GA) at a flow rate of 1.5 mL/h and an applied voltage of 15 kV. In comparison to pristine PLGA, dopamine-coated PLGA and collagen-hydroxyapatite composite nanofiber lamination has produced more wettable surfaces and surface wettability is found to higher with dopamine-coated PLGA fabrics then pristine PLGA. The SEM micrographs have clearly indicated that the lamination of polydopamine-coated PLGA fabric with collagen-hydroxyapatite composite nanofibers has shown increased adhesion of MC3T3E1 cells in comparison to pristine PLGA fabrics. The results of these studies have clearly demonstrated that collagen-nHA composites fibers may be used to create bioactive 3D scaffolds using PLGA as an architectural support agent.

  19. Daily consumption of the collagen supplement Pure Gold Collagen® reduces visible signs of aging

    Directory of Open Access Journals (Sweden)

    Borum

    2014-10-01

    Full Text Available Maryam Borumand, Sara Sibilla Minerva Research Labs Ltd., London, UK Abstract: With age, changes in the metabolic processes of structural components of the skin lead to visible signs of aging, such as increased dryness and wrinkle formation. The nutritional supplement, Pure Gold Collagen®, which consists of hydrolyzed collagen, hyaluronic acid, vitamins, and minerals, was developed to counteract these signs. An open-label study was conducted to investigate the effects of this nutritional supplement on skin properties. Supplementation with 50 mL of Pure Gold Collagen on a daily basis for 60 days led to a noticeable reduction in skin dryness, wrinkles, and nasolabial fold depth. In addition, a significant increase in collagen density and skin firmness was observed after 12 weeks. The data from this study suggest that Pure Gold Collagen can counteract signs of natural aging. Keywords: hydrolyzed collagen, antiaging, wrinkles, firmness, skin

  20. Collagen scaffolds loaded with collagen-binding NGF-beta accelerate ulcer healing.

    Science.gov (United States)

    Sun, Wenjie; Lin, Hang; Chen, Bing; Zhao, Wenxue; Zhao, Yannan; Xiao, Zhifeng; Dai, Jianwu

    2010-03-01

    Studies have shown that exogenous nerve growth factor (NGF) accelerates ulcer healing, but the inefficient growth factor delivery system limits its clinical application. In this report, we found that the native human NGF-beta fused with a collagen-binding domain (CBD) could form a collagen-based NGF targeting delivery system, and the CBD-fused NGF-beta could bind to collagen membranes efficiently. Using the rabbit dermal ischemic ulcer model, we have found that this targeting delivery system maintains a higher concentration and stronger bioactivity of NGF-beta on the collagen membranes by promoting peripheral nerve growth. Furthermore, it enhances the rate of ulcer healing through accelerating the re-epithelialization of dermal ulcer wounds and the formation of capillary lumens within the newly formed tissue area. Thus, collagen membranes loaded with collagen-targeting human NGF-beta accelerate ulcer healing efficiently.

  1. The structural analysis of three-dimensional fibrous collagen hydrogels by Raman microspectroscopy.

    Science.gov (United States)

    Hwang, Yu Jer; Lyubovitsky, Julia G

    2013-06-01

    To investigate molecular effects of 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), EDC/N-hydroxysuccinimide (NHS), glyceraldehyde cross-linking as well as polymerization temperature and concentration on the three-dimensional (3D) collagen hydrogels, we analyzed the structures in situ by Raman microspectroscopy. The increased intensity of the 814 and 936 cm(-1) Raman bands corresponding to the C-C stretch of a protein backbone and a shift in the amide III bands from 1241 cm(-1)/1268 cm(-1) in controls to 1247 cm(-1)/1283 cm(-1) in glyceraldehyde-treated gels indicated changes to the alignment of the collagen molecules, fibrils/fibers and/or changes to the secondary structure on glyceraldehyde treatment. The increased intensity of 1450 cm(-1) band and the appearance of a strong peak at 1468 cm(-1) reflected a change in the motion of lysine/arginine CH2 groups. For the EDC-treated collagen hydrogels, the increased intensity of 823 cm(-1) peak corresponding to the C-C stretch of the protein backbone indicated that EDC also changed the packing of collagen molecules. The 23% decrease in the ratio of 1238 cm(-1) to 1271 cm(-1) amide III band intensities in the EDC-modified samples compared with the controls indicated changes to the alignment of the collagen molecules/fibrils and/or the secondary structure. A change in the motion of lysine/arginine CH2 groups was detected as well. The addition of NHS did not induce additional Raman shifts compared to the effect of EDC alone with the exception of a 1416 cm(-1) band corresponding to a COO(-) stretch. Overall, the Raman spectra suggest that glyceraldehyde affects the collagen states within 3D hydrogels to a greater extent compared to EDC and the effects of temperature and concentration are minimal and/or not detectable.

  2. Subculture of chondrocytes on a collagen type I-coated substrate with suppressed cellular dedifferentiation.

    Science.gov (United States)

    Kino-Oka, Masahiro; Yashiki, Shino; Ota, Yuka; Mushiaki, Yuko; Sugawara, Katsura; Yamamoto, Takeyuki; Takezawa, Toshiaki; Taya, Masahito

    2005-01-01

    To evaluate the degree of cellular dedifferentiation, subculture of chondrocytes was conducted on a surface coated with collagen type I at a density of 1.05 mg/cm(2). In the primary culture, most of the cells were round in shape on the collagen (CL) substrate, whereas fibroblastic and partially extended cells were dominant on the polystyrene plastic (PS) substrate. Stereoscopic observation revealed that the round-shaped cells on the CL substrate were hemispherical with nebulous and punctuated F-actin filaments, whereas the fibroblastic cells on the PS substrate were flattened with fully developed stress fibers. This suggested that cell polarization was suppressed during culture on the former substrate. Although serial passages of chondrocytes through subcultures on the CL and PS substrates caused a decrease in the number of round-shaped cells, the morphological change was appreciably suppressed on the CL substrate, as compared with that on the PS substrate. It was found that only round-shaped cells formed collagen type II, which supports the view that cellular dedifferentiation can be suppressed to some extent on the CL substrate. Three-dimensional cultures in collagen gel were performed with cells isolated freshly and passaged on the CL or PS substrate. Cell density at 21 days in the culture of cells passaged on the CL substrate was comparable to that in the culture of freshly isolated cells, in spite of a significant reduction in cell density observed in the culture of cells passaged on the PS substrate. In addition, histological analysis revealed that the expression of glycosaminoglycans and collagen type II was of significance in the collagen gel with cells passaged on the CL substrate, and likewise in the gel with freshly isolated cells. This indicated that the CL substrate could offer a monolayer culture system for expanding chondrocyte cells.

  3. Surface Chemistry of Nanoscale Mineralized Collagen Regulates Periodontal Ligament Stem Cell Fate.

    Science.gov (United States)

    Fu, Yu; Liu, Shuai; Cui, Sheng-Jie; Kou, Xiao-Xing; Wang, Xue-Dong; Liu, Xiao-Mo; Sun, Yue; Wang, Gao-Nan; Liu, Yan; Zhou, Yan-Heng

    2016-06-29

    The interplay between stem cells and their extracellular microenvironment is of critical importance to the stem cell-based therapeutics in regenerative medicine. Mineralized collagen is the main component of bone extracellular matrix, but the effect of interfacial properties of mineralized collagen on subsequent cellular behaviors is unclear. This study examined the role of surface chemistry of nanoscale mineralized collagen on human periodontal ligament stem cell (hPDLSC) fate decisions. The intrafibrillarly mineralized collagen (IMC), fabricated by a biomimetic bottom-up approach, showed a bonelike hierarchy with nanohydroxyapatites (HAs) periodically embedded within fibrils. The infrared spectrum of the IMC showed the presence of phosphate, carbonate, amide I and II bands; and infrared mapping displayed uniform and higher spatial distribution of mineralization in the IMC. However, the distribution of the phosphate group differed far from that of the amide I group in the extrafibrillarly mineralized collagen (EMC), in which flowerlike HA clusters randomly depositing around the surface of the fibrils. Moreover, a large quantity of extrafibrillar HAs covered up the C═O stretch and N-H in-plane bend, resulting in substantial reduction of amide I and II bands. Cell experiments demonstrated that the hPDLSCs seeded on the IMC exhibited a highly branched, osteoblast-like polygonal shape with extended pseudopodia and thick stress fiber formation; while cells on the EMC displayed a spindle shape with less branch points and thin actin fibril formation. Furthermore, the biocompatibility of EMC was much lower than that of IMC. Interestingly, even without osteogenic induction, mRNA levels of major osteogenic differentiation genes were highly expressed in the IMC during cultivation time. These data suggest that the IMC with a similar nanotopography and surface chemistry to natural mineralized collagen directs hPDLSCs toward osteoblast differentiation, providing a promising

  4. A New Kind of Biomaterials-Bullfrog Skin Collagen

    Institute of Scientific and Technical Information of China (English)

    He LI; Bai Ling LIU; Hua Lin CHEN; Li Zhen GAO

    2003-01-01

    Pepsin-soluble collagen was prepared from bullfrog skin and partially characterized. This study revealed interesting differences, such as molecular weight, amino acid composition, denaturation temperature (Td), in the frog skin collagen when compared to the known vertebrate collagens. This study gives hints that bullfrog skin can be a potential, safe alternative source of collagen from cattle for use in various fields.

  5. Deformation and fracture of echinoderm collagen networks

    CERN Document Server

    Ovaska, Markus; Miksic, Amandine; Sugni, Michela; Di Benedetto, Cristiano; Ferrario, Cinzia; Leggio, Livio; Guidetti, Luca; Alava, Mikko J; La Porta, Caterina A M; Zapperi, Stefano

    2016-01-01

    Collagen networks provide the main structural component of most tissues and represent an important ingredient for bio-mimetic materials for bio-medical applications. Here we study the mechanical properties of stiff collagen networks derived from three different echinoderms and show that they exhibit non-linear stiffening followed by brittle fracture. The disordered nature of the network leads to strong sample-to-sample fluctuations in elasticity and fracture strength. We perform numerical simulations of a three dimensional model for the deformation of a cross-linked elastic fibril network which is able to reproduce the macroscopic features of the experimental results and provide insights into the internal mechanics of stiff collagen networks. Our numerical model provides an avenue for the design of collagen membranes with tunable mechanical properties.

  6. Nanoscale scraping and dissection of collagen fibrils.

    Science.gov (United States)

    Wenger, M P E; Horton, M A; Mesquida, P

    2008-09-24

    The main function of collagen is mechanical, hence there is a fundamental scientific interest in experimentally investigating the mechanical and structural properties of collagen fibrils on the nanometre scale. Here, we present a novel atomic force microscopy (AFM) based scraping technique that can dissect the outer layer of a biological specimen. Applied to individual collagen fibrils, the technique was successfully used to expose the fibril core and reveal the presence of a D-banding-like structure. AFM nanoindentation measurements of fibril shell and core indicated no significant differences in mechanical properties such as stiffness (reduced modulus), hardness, adhesion and adhesion work. This suggests that collagen fibrils are mechanically homogeneous structures. The scraping technique can be applied to other biological specimens, as demonstrated on the example of bacteria.

  7. Targeting collagen expression in alcoholic liver disease

    Institute of Scientific and Technical Information of China (English)

    Kyle J Thompson; Iain H McKillop; Laura W Schrum

    2011-01-01

    Alcoholic liver disease (ALD) is a leading cause of liver disease and liver-related deaths globally, particularly in developed nations. Liver fibrosis is a consequence of ALD and other chronic liver insults, which can progress to cirrhosis and hepatocellular carcinoma if left untreated. Liver fibrosis is characterized by accumulation of excess extracellular matrix components, including type Ⅰ collagen, which disrupts liver microcirculation and leads to injury. To date, there is no therapy for the treatment of liver fibrosis; thus treatments that either prevent the accumulation of type Ⅰ collagen or hasten its degradation are desirable. The focus of this review is to examine the regulation of type Ⅰ collagen in fibrogenic cells of the liver and to discuss current advances in therapeutics to eliminate excessive collagen deposition.

  8. The minor collagens in articular cartilage

    DEFF Research Database (Denmark)

    Luo, Yunyun

    2017-01-01

    Articular cartilage is a connective tissue consisting of a specialized extracellular matrix (ECM) that dominates the bulk of its wet and dry weight. Type II collagen and aggrecan are the main ECM proteins in cartilage. However, little attention has been paid to less abundant molecular components......, especially minor collagens, including type IV, VI, IX, X, XI, XII, XIII, and XIV, etc. Although accounting for only a small fraction of the mature matrix, these minor collagens not only play essential structural roles in the mechanical properties, organization, and shape of articular cartilage, but also...... fulfil specific biological functions. Genetic studies of these minor collagens have revealed that they are associated with multiple connective tissue diseases, especially degenerative joint disease. The progressive destruction of cartilage involves the degradation of matrix constituents including...

  9. Chondroitin Sulfate Perlecan Enhances Collagen Fibril Formation

    DEFF Research Database (Denmark)

    Kvist, A. J.; Johnson, A. E.; Mörgelin, M.

    2006-01-01

    produced in the presence of perlecan. Interestingly, the enhancement of collagen fibril formation is independent on the core protein and is mimicked by chondroitin sulfate E but neither by chondroitin sulfate D nor dextran sulfate. Furthermore, perlecan chondroitin sulfate contains the 4,6-disulfated......Inactivation of the perlecan gene leads to perinatal lethal chondrodysplasia. The similarity to the phenotypes of the Col2A1 knock-out and the disproportionate micromelia mutation suggests perlecan involvement in cartilage collagen matrix assembly. We now present a mechanism for the defect...... in collagen type II fibril assembly by perlecan-null chondrocytes. Cartilage perlecan is a heparin sulfate or a mixed heparan sulfate/chondroitin sulfate proteoglycan. The latter form binds collagen and accelerates fibril formation in vitro, with more defined fibril morphology and increased fibril diameters...

  10. Thermal stability of collagen triple helix.

    Science.gov (United States)

    Xu, Yujia

    2009-01-01

    Chief among the challenges of characterizing the thermal stability of the collagen triple helix are the lack of the reversibility of the thermal transition and the presence of multiple folding-unfolding steps during the thermal transition which rarely follows the simple two-state, all-or-none mechanism. Despite of the difficulties inherited in the quantitative depiction of the thermal transition of collagen, biophysical studies combined with proteolysis and mutagenesis approaches using full-chain collagens, short synthetic peptides, and recombinant collagen fragments have revealed molecular features of the thermal unfolding of the subdomains of collagen and led to a better understanding of the diverse biological functions of this versatile protein. The subdomain of collagen generally refers to a segment of the long, rope-like triple helical molecule that can unfold cooperatively as an independent unit whose properties (their size, location, and thermal stability) are considered essential for the molecular recognition during the self-assembly of collagen and during the interactions of collagen with other macromolecules. While the unfolding of segments of the triple helix at temperatures below the apparent melting temperature of the molecule has been used to interpret much of the features of the thermal unfolding of full-chain collagens, the thermal studies of short, synthetic peptides have firmly established the molecular basis of the subdomains by clearly demonstrating the close dependence of the thermal stability of a triple helix on the constituent amino acid residues at the X and the Y positions of the characteristic Gly-X-Y repeating sequence patterns of the triple helix. Studies using recombinant collagen fragments further revealed that in the context of the long, linear molecule, the stability of a segment of the triple helix is also modulated by long-range impact of the local interactions such as the interchain salt bridges. Together, the combined approaches

  11. Properties of Chitosan-Laminated Collagen Film

    Directory of Open Access Journals (Sweden)

    Vera Lazić

    2012-01-01

    Full Text Available The objective of this study is to determine physical, mechanical and barrier properties of chitosan-laminated collagen film. Commercial collagen film, which is used for making collagen casings for dry fermented sausage production, was laminated with chitosan film layer in order to improve the collagen film barrier properties. Different volumes of oregano essential oil per 100 mL of filmogenic solution were added to chitosan film layer: 0, 0.2, 0.4, 0.6 and 0.8 mL to optimize water vapour barrier properties. Chitosan layer with 0.6 or 0.8 % of oregano essential oil lowered the water vapour transmission rate to (1.85±0.10·10–6 and (1.78±0.03·10–6 g/(m2·s·Pa respectively, compared to collagen film ((2.51±0.05·10–6 g/(m2·s·Pa. However, chitosan-laminated collagen film did not show improved mechanical properties compared to the collagen one. Tensile strength decreased from (54.0±3.8 MPa of the uncoated collagen film to (36.3±4.0 MPa when the film was laminated with 0.8 % oregano essential oil chitosan layer. Elongation at break values of laminated films did not differ from those of collagen film ((18.4±2.7 %. Oxygen barrier properties were considerably improved by lamination. Oxygen permeability of collagen film was (1806.8±628.0·10–14 cm3/(m·s·Pa and values of laminated films were below 35·10–14 cm3/(m·s·Pa. Regarding film appearance and colour, lamination with chitosan reduced lightness (L and yellowness (+b of collagen film, while film redness (+a increased. These changes were not visible to the naked eye.

  12. Corneal collagen cross-linking

    Directory of Open Access Journals (Sweden)

    Jankov II Mirko

    2010-01-01

    Full Text Available Corneal collagen cross-linking (CXL with riboflavin and ultraviolet-A (UVA is a new technique of corneal tissue strengthening by using riboflavin as a photosensitizer and UVA to increase the formation of intra- and interfibrillar covalent bonds by photosensitized oxidation. Keratocyte apoptosis in the anterior segment of the corneal stroma all the way down to a depth of about 300 microns has been described and a demarcation line between the treated and untreated cornea has been clearly shown. It is important to ensure that the cytotoxic threshold for the endothelium has not been exceeded by strictly respecting the minimal corneal thickness. Confocal microscopy studies show that repopulation of keratocytes is already visible 1 month after the treatment, reaching its pre-operative quantity and quality in terms of functional morphology within 6 months after the treatment. The major indication for the use of CXL is to inhibit the progression of corneal ectasias, such as keratoconus and pellucid marginal degeneration. CXL may also be effective in the treatment and prop