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When developing, the mandible presents great plasticity and contains condensed mesenchymal cells that develops into Meckel's cartilage, of which the anterior part forms the mandibular symphysis. Mandible human development studies focus on investigating whether the beginning of mandibular fusion in fetal period is related to symphysis ossification and the tensions imposed on it, considering that tongue movements, mouth opening, and closing can be seen in fetuses. This research analyses tissue modifications during human mandibular symphysis growth using light and scanning electron microscopy to relate them to its functional structure. The study sample consisted of 12 human fetuses distributed into two groups: Group I (GI) of 10–14 weeks old and Group II (GII) of 20–24 weeks old. Fragments of mandibular symphysis were removed en bloc together with the surrounding tissues to preserve the relation with adjacent structures. Decalcified specimens were prepared in semi‐serial coronal sections 5‐μm‐thick and stained with hematoxylin and eosin, Masson՚s trichrome, Verhoeff, and Sirius red for histological analysis with light microscopy. Collagen fibers Type I or III and elastic fibers were quantified by volume fraction (Vv). Coronal sections of the GI and GII symphyseal region were submitted to scanning electron microscopy. Comparison between groups used independent t‐test. Our study presents the different endochondral ossification stages in the anterior part of Meckel's cartilage in GI. Both groups showed abundantly vascularized mesenchymal tissue with intense cellular activity forming the mandibular symphysis, such as a source of new osteoblasts adjacent to the newly deposited bone matrix. Scanning electron microscopy analysis revealed an invasion of the bony trabecula in the transverse direction from the hemimandible, rectilinear in GI and sinuous in GII due to interdigitating bone process, promoting its ossification. In collagen Vv analysis was verified a prevalence of type I in GII and type III in GI, indicating a proportional relation between maturation and tissue arrangement. Functionally, the collagen and elastic fibers in the mandibular symphysis were arranged in a pantographic network, and the fibrillar interconnectivity clearly contributes to resilience capacity and efficiency of the force transfer. This study inferred the functional significance of the knowledge about the tissue composition of mandibular symphysis, and the importance of this tissue for surrounding structures. The mesenchymal tissue of mandibular symphysis participates in bone growth process, revealing an adaptation mechanism of mandibular symphysis in the fetal period investigated. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of the estrogen depression during orthodontic tooth movement on alveolar bone microarchitecture and periodontal ligament. Female Wistar rats were divided into two groups, one consisting of non‐ovariectomized animals subjected to orthodontic tooth movement, and one comprising ovariectomized animals subjected to orthodontic tooth movement. Micro‐CT assessment of bone volume to total volume (BV/TV), total porosity, trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp) in the alveolar bone of the orthodontically moved tooth was performed. Histomorphometric analyses were made in the periodontal ligament, and immunoexpression of RANK, RANKL, OPG, and TUNEL were quantified. Orthodontic tooth movement in the group of ovariectomized rats was faster than in non‐ovariectomized animals. The alveolar bone area showed lower values of BV/TV and trabecular thickness, and higher bone porosity and trabeculae numbers in the ovariectomized rats. Histological analyses in the ovariectomized group revealed an increase in collagen fibers in the periodontal ligament. The apoptotic cell counts in the periodontal ligament were higher in the group of ovariectomized rats than in the sham‐operated rats. Ovariectomy resulted in an increase in tooth movement and alteration of the alveolar bone microstructure in the first 7 day of orthodontic tooth movement, and in the presence of apoptotic cells in the periodontal ligament. [ABSTRACT FROM AUTHOR]

Background: The negative effects of skin aging are primarily related to the destruction of dermal architectural structure. More specifically, this includes changes in the spatial arrangement of collagen, elastin fibers, mucopolysaccharides, proteoglycans, and ground substances. Aims: The purpose of this study is to investigate the histologic effects of dermal and subdermal tissue after a controlled single treatment with radiofrequency (RF) macroneedling. This therapy provides a controlled, localized, thermal effect on the dermis whereby triggering the body's own healing processes of extracellular matrix remodeling. Clinically benefits include skin tightening. Methods: Biopsies were obtained for histologic evaluation from four patients (n = 4), 4 weeks after completing a single RF macroneedling facial treatment. Results: Age‐related changes of the dermal and subdermal architecture were observed at baseline. After treatment, all biopsies demonstrated an increase in epidermal cells, collagen, elastin, fibroblasts, vasculature, and a decrease in inflammatory cells. Conclusions: The results of this histologic study confirm a significant "subsurfacing" thermal effect from the noncoagulative ascendant thermal injury. The obtained results characterize RF macroneedling therapy as an effective method for correcting age‐related changes in facial skin. [ABSTRACT FROM AUTHOR]

Flexible electric heaters with softness, comfort and heating performance have application prospects in the fields of life and health, medical security and so on. In this study, by taking advantage of the soft and comfortable properties of leather itself, collagen fibers and carbon nanotubes (CNTs) are composited through zirconium ion (Zr4+) coordination and complexation. The composition, microstructure and Joule heating performance of the prepared flexible conductive leather (CNTs@Zr@OTL) are investigated in detail. The characterisation results prove the (Zr4+) coordination effect and the successful preparation of CNTs@Zr@OTL. At the same time, it has a resistance of about 250 Ω, a shrinkage temperature (Ts) of about 75°C, mechanical property of about 8 MPa, 60 h strong biodegradability and Joule heating of about 65°C under 15 V DC voltage. The obtained product can be further designed as a flexible Joule heating heater (Jhh) with softness, comfort as well as conductivity, and excellent Joule heating performance, and its practical application effect in heating wrists, fingers, joints and car seats is explored, as well as the heating effect under the actual movement of human body such as squatting, sitting and walking. This work provides an idea and method for the intelligent interaction of flexible heaters. [ABSTRACT FROM AUTHOR]

Objectives: By comparing with the control group, we evaluated the usefulness of contrast‐enhanced ultrasound (CEUS) combined with elastography for the assessment of muscle invasion by bladder cancer (MIBC) in a Sprague–Dawley (SD) rat model. Methods: In the experimental group, 40 SD rats developed in situ bladder cancer (BLCA) in response to N‐methyl‐N‐nitrosourea treatment, whereas 40 SD rats were included in the control group for comparison. We compared PI, Emean, microvessel density (MVD), and collagen fiber content (CFC) between the two groups. In the experimental group, Bland–Altman test was used to assess the relationships between various parameters. The largest Youden value was used as the cut‐off point, and binomial logistic regression analysis was performed to analyze the PI and Emean. Receiver operating characteristic (ROC) curve analysis was performed to determine the diagnostic power of parameters, individually and in combination. Results: The PI, Emean, MVD, and CFC were significantly lower in the control group than in the experimental group (P <.05). The PI, Emean, MVD, and CFC were significantly higher for MIBC than for non‐muscle‐invasive bladder cancer (P <.05). There were significant correlations between PI and MVD, and between Emean and CFC. The diagnostic efficiency analysis showed PI had the highest sensitivity, CFC had the highest specificity, and PI + Emean had the highest diagnostic efficacy. Conclusion: CEUS and elastography can distinguish lesions from normal tissue. PI, MVD, Emean, and CFC were useful for the detection of BLCA myometrial invasion. The comprehensive utilization of PI and Emean improved diagnostic accuracy and have clinical application. [ABSTRACT FROM AUTHOR]

Constructing proper in vitro tumor immune microenvironment (TIME) is important for cancer immune‐therapy studies, while the selection of biomaterials is critical. As innate immune cells, macrophages can target and kill cancer cells in vivo at the early stage of tumor development. However, this targeting phenomenon has not been observed in vitro. Herein, a quasi‐3D in vitro cell culture model is constructed to mimic TIME by integrating hydrogel collagen as extracellular matrix for cells. In the collagen‐based quasi‐3D in vitro system, for the first time, it is found that macrophages can be attracted toward cancer cells along the dynamically reconstructed collagen fibers. By combining traction force microscopy and customized micro‐manipulator system, it is revealed that the collagen matrix‐transmitted tensile force signaling precisely guides the migration of macrophages toward cancer cells. The mechano‐responsiveness mechanism is related to the activation of mechanosensitive ion channels, and the induced local increase of calcium signal, which is proved to enhance the F‐actin assembly and to guide the cell migration. This novel mechanism advances the understanding of the role of collagen fibers in mechanotaxis of macrophages. Taken together, it has great potential for assisting biomaterial designs in developing new drug‐screening models and clinical strategies for cancer immune‐therapy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Textural deterioration is a serious problem in chilled fish flesh. Cysteine proteinases are proposed to participate in disintegration of collagen fibers during this process, while its mechanism remains elusive. In the present study, a cysteine proteinase was purified from grass carp muscle and identified by mass spectrometry, and its effect on structural changes of collagen fibers was investigated. RESULTS: During storage at 4 °C, cysteine proteinase activity in fillets increased to 1.53‐fold at day 5 and maintained a high level later, and this variable was related to a decline in shear force and an increase in drip loss. A 29 kDa cysteine proteinase was purified through ammonium sulfate precipitation and column chromatography, and identified as cathepsin L. Cathepsin L caused collagen fibers to partly disintegrate into fibril bundles and individual fibrils at 48 h, while the triple helical structure of collagen molecules remained stable. Release of soluble proteins and glycosaminoglycans from cathepsin L‐treated collagen fibers was time dependent, coinciding with a release of 4.12 ± 0.13% and 8.57 ± 0.03% at 48 h respectively. However, 0.85 ± 0.02% of hydroxyproline was freed from cathepsin L‐treated collagen fibers at 48 h. Furthermore, scanning electron microscopy revealed that the inhibitory effect of cathepsin L could retard the destruction of intramuscular connective tissues (IMCTs). CONCLUSION: These results indicated that cathepsin L might be involved in collagen fiber breakdown by degrading collagen‐associated proteoglycans during textural deterioration of grass carp. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Degeneration of articular cartilage is often triggered by a small tissue crack. As cartilage structure and composition change with age, the mechanics of cracked cartilage may depend on the tissue age, but this relationship is poorly understood. Here, we investigated cartilage mechanics and crack deformation in immature and mature cartilage exposed to a full‐thickness tissue crack using indentation testing and histology, respectively. When a cut was introduced, tissue cracks opened wider in the mature cartilage compared to the immature cartilage. However, the opposite occurred upon mechanical indentation over the cracked region. Functionally, the immature‐cracked cartilages stress‐relaxed faster, experienced increased tissue strain, and had reduced instantaneous stiffness, compared to the mature‐cracked cartilages. Taken together, mature cartilage appears to withstand surface cracks and maintains its mechanical properties better than immature cartilage and these superior properties can be explained by the structure of their collagen fibrous network. [ABSTRACT FROM AUTHOR]

In this study multiphoton tomography, based on second harmonic generation (SHG), and two‐photon‐excited fluorescence (TPEF) was used to visualize both the extracellular matrix and tumor cells in different morphological and molecular subtypes of human breast cancer. It was shown, that quantified assessment of the SHG based imaging data has great potential to reveal differences of collagen quantity, organization and uniformity in both low‐ and highly‐ aggressive invasive breast cancers. The values of quantity and uniformity of the collagen fibers distribution were significantly higher in low‐aggressive breast cancer compared to the highly‐aggressive subtypes, while the value representing collagen organization was lower in the former type. Additionally, it was shown, that TPEF detection of elastin fibers and amyloid protein may be used as a biomarker of detection the low‐aggressive breast cancer subtype. Thus, TPEF/SHG imaging offers the possibility of becoming a useful tool for the rapid diagnosis of various subtypes of breast cancer during biopsy as well as for the intraoperative determinination of tumor‐positive resection margins. [ABSTRACT FROM AUTHOR]

Intracutaneous transplantation of trichogenic cells is a currently endorsed strategy to realize hair regeneration in vivo. However, skin is not the most advantageous transplant site due to the robust mechanical property and deficient physiological perfusion. Herein, a subcutaneous space made of prevascularized collagen fibers (PVCF) generated by controlling the duration of in situ foreign body reaction is reported. In contrast to skin, an optimally preprogrammed PVCF presents a larger tissue volume (171 mm3), low Young's modulus (1/2‐fold), high flexibility high mechanical energy dissipation rate (1.3‐fold), highly permeable surface structure, and plentiful vascular network. Remarkably, cells transplanted into PVCF suffer less apoptosis and necrosis, and generate more mature hairs (≈289 per site) than that in intracutaneous transplantation (≈177 per site). The RNA‐sequencing profiling indicates similar trends under molecular level. This work provides a promising strategy to improve graft site microenvironment physiologically and mechanically, with a low‐cost and simple fabrication process. [ABSTRACT FROM AUTHOR]

BACKGROUND: Collagen fibers from tannery solid wastes were treated with aqueous solutions of inorganic salts. The effect of the inorganic salts on the dissolution of collagen fibers and degradation of collagen were investigated. Tests of reduced viscosity and sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS‐PAGE) were applied to evaluate the degree of degradation during the dissolution process. The specific ionic effects of the Hofmeister series on the dissolution of collagen fibers in salt aqueous solutions were demonstrated. RESULTS: According to all the results, the dissolution abilities of inorganic salts were in the order of Br− > Cl− > SCN− > CH3COO− > H2PO4− > CO32− as well as Na+ > Mg2+ > Ca2+ > NH4+ > K+ > Li+. The results indicated that NaBr aqueous solution could have potential ability as a solvent to dissolve collagen fibers without excessive degradation of collagen. CONCLUSIONS: NaBr aqueous solution could have potential ability as a solvent to dissolve collagen fibers without excessive degradation of collagen. By analyzing the results of the reduced viscosity tests, SDS‐PAGE and amino analysis, proper dissolution conditions were evaluated with the conditions of NaBr aqueous solution concentration of 1 mol L−1, contacting time of 4 h and temperature of 60 °C. From amino analysis and in situ optical microscopy observation, a possible process of collagen fiber dissolution in NaBr solution was demonstrated. This work provides a method for treating and recycling tannery solid wastes with some information for the investigation of collagen‐based materials. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The healing capacity of bone marrow mesenchymal stem cells (BMMSCs) has been evaluated in various studies. This study aimed to evaluate the effect of BMMSCs on the healing of temporomandibular joints (TMJs) with induced rheumatoid arthritis. Fifty healthy male Sprague Dawley rats were divided into three groups: group I (n = 10), negative control; group II (n = 20), positive control (induction of arthritis by adjuvant followed by intravenous injection of 0.1 ml of PBS); and group III (n = 20), intervention (as for group II but injected intravenously with 1 × 106 cells ml−1 of BMMSCs suspended in PBS). Half of the rats in each group were euthanized 3 wk after the start of the experiment and the other half was euthanized after 5 wk. Group I revealed normal TMJ features. Group II showed thickening of disc, thinning of cartilage, disordered bone trabeculae, and decreased in mean % area staining positive of collagen fibers at 3 wk, while at 5 wk these effects were more aggravated. Group III showed nearly normal thickness of disc and condylar cartilage, nearly normal arrangement of bone trabeculae and regenerated collagen fibers at 3 wk, while after 5 wk the TMJ features were almost normal. Two‐way anova revealed statistically significant differences between groups. Thus, treatment of induced rheumatoid arthritis with BMMSCs shows promising results that need to be further investigated in humans. [ABSTRACT FROM AUTHOR]

Background: Microdermabrasion and chemical peeling are popular, inexpensive, and safe methods for treatment of some skin disorders and to rejuvenate skin. Objectives: To study the alterations of the dermal connective tissue following salicylic acid peeling and microdermabrasion. Methods: Twenty patients were participated in our study. All participants underwent facial salicylic acid 30% peel or microdermabrasion (10 cases in each group) weekly for 6 weeks. Punch biopsies were obtained from the clinically normal skin of the right postauricular region 1 week before treatment (control group). Other punch skin biopsies were obtained 1 week after the end of the treatments from the left postauricular area. This region was treated in a similar way to the adjacent lesional skin (treated group). We used routine histological techniques (H&E stain), special stains (Masson trichrome and orcein stains), and image analyzer to study the alterations of the dermal connective tissues. Results: Our study demonstrates variations in the morphological changes between the control and the treated groups, and between chemical peels and microdermabrasion. Both salicylic acid 30% and microdermabrasion were associated with thickened epidermal layer, shallow dermal papillae, dense collagen, and elastic fibers. There was a significant increase among those treated sites vs control regarding epidermal thickness and collagen thickness. Also, there was a highly statistically significant increase among those treated with salicylic acid vs microdermabrasion regarding the epidermal, collagen, and elastin thickness. Conclusions: Both methods stimulate the repair process. The mechanisms underlying these variations are open for further investigations. [ABSTRACT FROM AUTHOR]

Various chemical, natural, or synthetic in origin, crosslinking methods have been proposed over the years to stabilise collagen fibers. However, an optimal method has yet to be identified. Herein, we ventured to assess the potential of 4-star poly(ethylene glycol) ether tetrasuccinimidyl glutarate, as opposed to glutaraldehyde (GTA), genipin and carbodiimide, on the structural, physical and biological properties of collagen fibers. The 4-star poly(ethylene glycol) ether tetrasuccinimidyl glutarate induced an intermedium surface smoothness, denaturation temperature and swelling. The 4-star poly(ethylene glycol) ether tetrasuccinimidyl glutarate fibers had significantly higher stress at break values than the carbodiimide fibers, but significantly lower than the GTA and genipin fibers. With respect to strain at break, no significant difference was observed among the crosslinking treatments. The 4-star poly(ethylene glycol) ether tetrasuccinimidyl glutarate fibers exhibited significantly higher cell metabolic activity and DNA concentration that all other crosslinking treatments, promoted consistently cellular elongation along the longitudinal fiber axis and by day 7 they were completely covered by cells. Collectively, this work clearly demonstrates the potential of 4-star poly(ethylene glycol) ether tetrasuccinimidyl glutarate as collagen crosslinker. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 914-922, 2016. [ABSTRACT FROM AUTHOR]

The aim of this research was to investigate the impact of calcium channel blockers (verapamil) on the formation of scars in the sciatic nerve anastomosis after peripheral nerve injury. One hundred twenty healthy, male Sprague- Dawley rats were selected and prepared with right sciatic nerve injury for this study. Samples were selected at the fourth and 12th weeks, respectively, after treatment and observations were made on the nerve anastomosis healing and diameter. Image analysis and statistical processing were carried out relating to the results of the study. The diameter of the anastomosis of the treatment group at weeks 4 and 12 was noticeably smaller than the control group ( P < 0.05). In the treatment group at week 4, there were many vesicles observed in the fibroblasts' cytosol and in the control group, the fibroblasts exhibited high number of rough endoplasmic reticulum. The collagen content of the nerve scarring at week 12 in the treatment group was apparently less than the control group ( P < 0.01). The calcium channel blocker (verapamil) reduced the axon resistance through the anastomosis during nerve regeneration. It can effectively inhibit the formation of scarring from nerve injury. It also provided an excellent microenvironment for the regeneration of nerve fibers. [ABSTRACT FROM AUTHOR]

Objectives To investigate soft tissue histomorphology and quality around implants with a modified transgingival collar surface comparatively to a machined. Material and methods Twenty-seven Straumann Standard Tissue Level implants belonging to the following groups (nine of each group): Ti mod SLA with machined collar ( Ti- M), Ti mod SLA with machined, acid-etched surface collar ( Ti-mod MA), and Ti Zr mod SLA with machined, acid-etched surface collar ( Ti Zr-mod MA) were placed in the mandible of six minipigs. After 8 weeks of healing, buccal sections were obtained and processed for histological evaluation. Results Histometric soft tissue outcomes were similar for the three types of implants. The percentage of connective tissue attached to implant surface and its length was longer at Ti Zr-mod MA with respect to Ti- M implants. The number of inflammatory cells was slightly higher at the Ti Zr-mod MA with respect to Ti- M implant. The percentage of area occupied by perpendicular collagen fibers was slightly higher for the modified surfaces in comparison with the machined. Conclusions Modified implant collar surfaces at Ti and Ti Zr implants showed a soft tissue interface similar to machined. A tendency of increasing number of perpendicular collagen fibers and improved connective tissue contact was found at the modified implant surfaces. [ABSTRACT FROM AUTHOR]

ABSTRACT Little is known about collagen arrangement in the space of Disse was related to the fluid flow both in normal and cirrhotic liver. We examined the changes in the arrangement of type-I collagen in thioacetamide-induced cirrhotic rat livers with immunohistochemistry and SEM after maceration of the noncollagenous tissues with NaOH. The sparse bundles of collagen fibers in the spaces of Disse were mostly elongated fibers with a disorganized arrangement in each nodule. They connected with the broad fibrous septa. Based on a comparison of the architecture of the collagen fibers and the established flow of fluid in the space of Disse, we hypothesize that the fluid in the space of Disse streams along collagen fibers in all directions to broad fibrous septa. The appearance of perinodular plexus in cirrhotic rat livers probably helps to reduce portal hypertension. Microsc. Res. Tech. 78:187-193, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

ABSTRACT The plantaris longus tendon (PLT) in bullfrog develops a fibrocartilage-like tissue in the area that is functionally subject to compressive forces. The aim of this study was to analyze the modifications of the pressure-bearing region in bullfrog PLT with different ages (7, 180, and 1,080 days after the end of metamorphosis) using histomorphometric, ultrastructural and biochemical methods. Weak basophilia and cells with a fibroblastic phenotype were observed in the compression region at 7 days of age. On the other hand, a large area of intense tissue basophilia associated with a chondroblast-like cell population was noted at the other ages. Collagen fibers exhibited a three-dimensional network-like arrangement at all ages. The number of connective tissue cells increased between 7 and 180 days of age and was reduced in older animals. The 180-day-old animals presented a well-developed pericellular matrix rich in proteoglycans. The mean diameter of collagen fibrils increased from 7 to 180 days and was the same at 1,080 days. Glycosaminoglycan content was higher in 7-day-old animals. A higher amount of hydroxyproline was observed at 180 and 1,080 days. The swelling test showed a significant increase of wet weight in 7-day-old animals. In conclusion, the alterations that occur in the pressure-bearing of bullfrog PLT are the result of physiological alterations of the animal with the maturation and aging. Microsc. Res. Tech. 77:797-805, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Background A quantitative understanding of the histological alteration of the skin is important for assessing the severity of photoaging. Methods We performed Elastica-van Gieson staining and immunohistochemistry for decorin on 34 facial skin sections. We evaluated the alteration of collagen fibers and decorin (a modulator for collagen fibrillogenesis), according to the 5 grades of morphological change in elastic fibers that was established by Kligman (1969). The objectivity of a stage (Stages I-VI), which was established in this study, was evaluated using weighted kappa statistical analysis based on the degree of agreement in stage determination by 11 observers using a blind procedure. Correlation between the crow's-feet-area wrinkles grades of another 26 women and stages was also analyzed. Results The initial alteration of elastic fibers was observed in the deep dermis. Decorin was not detected in very severely altered skin. Based on the combination of changes in the elastic fibers, collagenic fibers, and decorin, skin tissues were categorized into 6 stages according to severity. The statistical analysis showed almost perfect agreement between observers. Significant positive correlation between stages and wrinkle scores was found. Conclusions We propose a new objective histological scale that is useful for assessing the severity of photoaging. [ABSTRACT FROM AUTHOR]

Elastin fibers are major extracellular matrix macromolecules that are critical in maintaining the elasticity and resilience of tissues such as blood vessels, lungs and skins. However, the role of elastin in articular cartilage is poorly defined. The present study investigated the organization of elastin fiber in articular cartilage, its relationship to collagen fibers and the architecture of elastin fibers from different mechanical environments by using a kangaroo model. Five morphologies of elastin fibers were identified: Straight fiber, straight fiber with branches, branching fibers directly associated with chondrocyte, wave fiber and fine elastin. The architecture of the elastin network varied significantly with cartilage depth. In the most superficial layer of tibial plateau articular cartilage, dense elastin fibers formed a distinctive cobweb-like meshwork which was parallel to the cartilage surface. In the superficial zone, elastin fibers were well organized in a preferred orientation which was parallel to collagen fibers. In the deep zone, no detectable elastin fiber was found. Moreover, differences in the organization of elastin fibers were also observed between articular cartilage from the tibial plateau, femoral condyle, and distal humerus. This study unravels the detailed microarchitecture of elastin fibers which display a well-organized three-dimensional versatile network in articular cartilage. Our findings imply that elastin fibers may play a crucial role in maintaining the integrity, elasticity, and the mechanical properties of articular cartilage, and that the local mechanical environment affects the architectural development of elastin fibers. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1345-1353, 2013 [ABSTRACT FROM AUTHOR]

Problems associated with current bone substitutes led to an increased interest in tissue engineered surrogates with properties similar to natural bones. Commonly used materials lack the ultimate mechanical properties. In this study, we examined the influence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) as a crosslinking agent on the strength of collagen fibers. Collagen fibers are crosslinked with EDC, or EDC/ N-hydroxysulfosuccinimide (Sulfo-NHS) in water or EDC in acetone. After which fibers are mineralized using calcium chloride and potassium phosphate. The mechanical properties of the treated fibers are measured using tensile testing. In addition, the effect of crosslinking on cellular behavior was tested by culturing bone marrow mesenchymal stem cells (BMMSCs) on modified fibers. We found that the mechanical properties of non-mineralized and mineralized collagen fibers are significantly affected by the crosslinking method. The tensile strength of single fibers is greatly improved by crosslinking with EDC in acetone. BMMSCs were found to attach and spread well on modified fibers confirming biocompatibility. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 2507-2514, 2013. [ABSTRACT FROM AUTHOR]

A method based on angle-sensitive magnetic resonance imaging for determining unknown orientations of collagen fibers in ligaments is presented. Collagen fibers were stepwise rotated around two independent axes within a 3T magnetic resonance tomograph (from 0° to 180°, step size = 10°). Analyzing the magnetic resonance signal intensity of each voxel as a function of the rotation angle, directions were calculated by means of a computational algorithm. The accuracy of the algorithm was validated using 1000 random test directions, revealing an average deviation of 4.4° (median ± standard deviation: 2.7° ± 9°). Subsequently, the presented method was applied to three specimens of the human iliotibial tract mounted in different directions in a rotatable plastic box. Polarized light microscopy was used to verify parallel alignment of the collagen fibers in the three specimens. The calculated directions were compared with the directions of the specimens. Analyzing each voxel separately, average deviations (median ± standard deviation) in the three specimens were: 11.2° (3.6° ± 20.4°), 12° (5° ± 24.1°), and 20.4° (8.7° ± 27°). If the magnetic resonance signal intensity of each voxel was averaged with the intensity of immediately neighboring voxels, average deviations (median ± standard deviation) were 8.5° (3.6° ± 17.4°), 6.2° (0° ± 18°), and 9.2° (5° ± 19.2°). The presented method has the potential to be applied in situ to anatomical structures like cartilage, ligaments, tendons and fascia. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

To identify the forces that may exist in the parabronchus of the avian lung and that which may explain the reported strengths of the terminal respiratory units, the air capillaries and the blood capillaries, the arrangement of the parabronchial collagen fibers (CF) of the lung of the domestic fowl, Gallus gallus variant domesticus was investigated by discriminatory staining, selective alkali digestion, and vascular casting followed by alkali digestion. On the luminal circumference, the atrial and the infundibular CF are directly connected to the smooth muscle fibers and the elastic tissue fibers. The CF in this part of the parabronchus form the internal column (the axial scaffold), whereas the CF in the interparabronchial septa and those associated with the walls of the interparabronchial blood vessels form the external, i.e. the peripheral, parabronchial CF scaffold. Thin CF penetrate the exchange tissue directly from the interparabronchial septa and indirectly by accompanying the intraparabronchial blood vessels. Forming a dense network that supports the air and blood capillaries, the CF weave through the exchange tissue. The exchange tissue, specifically the air and blood capillaries, is effectively suspended between CF pillars by an intricate system of thin CF, elastic and smooth muscle fibers. The CF course through the basement membranes of the walls of the blood and air capillaries. Based on the architecture of the smooth muscle fibers, the CF, the elastic muscle fibers, and structures like the interparabronchial septa and their associated blood vessels, it is envisaged that dynamic tensional, resistive, and compressive forces exist in the parabronchus, forming a tensegrity (tension integrity) system that gives the lung rigidity while strengthening the air and blood capillaries. [ABSTRACT FROM AUTHOR]

Incisional wounds in rats treated locally with thymosin β4 (Tβ4) healed with minimal scaring and without loss in wound breaking strength. Treated wounds were significantly narrower in width. Polarized light microscopy treated wounds had superior organized collagen fibers, displaying a red birefringence, which is consistent with mature connective tissue. Control incisions had randomly organized collagen fibers, displaying green birefringence that is consistent with immature connective tissue. Immunohistology treated wounds had few myofibroblasts and fibroblasts with α smooth muscle actin (SMA) stained stress fibers. Polyvinyl alcohol sponge implants placed in subcutaneous pockets received either carrier or 100 μg of Tβ4 on days 2, 3, and 4. On day 14, treated implants revealed longer, thicker collagen fiber bundles with intense yellow-red birefringence by polarized light microscopy. In controls, fine, thin collagen fiber bundles were arranged in random arrays with predominantly green birefringence. Controls contained mostly myofibroblasts, while few myofibroblasts appeared in Tβ4 treated implants. Electron microscopy confirmed both cell types and the degree of collagen fiber bundle organization. Our results demonstrate that Tβ4 treated wounds appear to mature earlier and heal with minimal scaring. [ABSTRACT FROM AUTHOR]

Objective: To investigate the significance of tympanic membrane collagen fiber layers in high frequency sound transmission. Study Design: Human cadaver temporal bone study. Methods: Laser Doppler vibrometry was used to measure stapes footplate movement in response to acoustic stimulation. The tympanic membrane was altered by creating a series of slits and applying paper patches to isolate the effects of specifically oriented collagen fibers. Three groups of membrane alterations were evaluated: 1) circumferentially oriented slits involving each quadrant to primarily disrupt radial fibers, made sequentially within superior-anterior, inferior-anterior, inferior-posterior, and superior-posterior quadrants; 2) the same slits made in the reverse order; and 3) radially oriented slits from the umbo to the annulus to primarily disrupt circumferential fibers. For each group, measurements of the middle-ear cavity pressure, ear canal pressure, and stapes velocity were made each time the tympanic membrane was altered. Results: Regardless of the order in which the circumferentially oriented slits were made, there was a consistent decrease in stapes velocity above 4 kHz for the third and fourth cuts compared to the control. The mean decrease in the range of 4 to 12.5 kHz was 11 dB for the third patched slit and 14 dB for the fourth patched slit ( P < .01). Radially oriented slits appear to produce smaller effects. Conclusions: Radial collagen fibers in the tympanic membrane play an important role in the conduction of sound above 4 kHz. [ABSTRACT FROM AUTHOR]

Objectives: To analyze the presence and distribution of collagen fibers and versican in human vocal fold lamina propria of fetal larynges. Study Design: Cross sectional analysis of cadaveric vocal folds of human fetuses. Methods: Seven fetal larynges obtained from 28- to 36-week-old fetuses were analyzed with the Picrosirius-polarization method, immunohistochemistry, and image analysis. Results: Collagen fibers within the lamina propria exhibited a monolaminar distribution pattern and spatial arrangement in 'wicker basket.' Versican distribution was larger in the superficial and intermediate layers when compared to the deep layer. Conclusion: Our findings suggest that collagen and versican distribution and arrangement within the lamina propria in the developing fetus are important for vocalization at birth. [ABSTRACT FROM AUTHOR]

Abstract: Epithelial cells from involuting rat ventral prostate (VP) express Matrilysin (MMP-7) mRNA. Herein, we investigated by immunohistochemistry the MMP-7 protein location and its association with tissue changes following castration in the VP. Normal and castrated adult male Wistar rats were sacrificed at different times after surgery. VP was examined by immunocytochemistry and immunoprecipitation. Castration promoted a shrinking of prostate ducts with an extensive stromal remodeling. In the VP from normal rats, MMP-7 immunoreactivity was found in epithelial secretory granules. Three days after castration, immunostaining for MMP-7 was found in both the epithelial secretory granules and in the stroma just below the epithelium, mainly at the distal ductal tips. At seven and 21days after castration, the immunostaining for MMP-7 was found only in the stromal space. Immunoprecipitation confirmed the specificity of the primary antibody by rescuing a pro-enzyme form (28kDa) in the prostate extracts. The present results suggest that MMP-7 participates in the epithelial-stromal interface remodeling of the ventral prostate during the involution achieved by castration, probably in the degradation of components of the epithelial basement membrane. [Copyright &y& Elsevier]

Abstract: A quantitative morphometric evaluation of the intramural plexus of the urinary bladder of adult and aged guinea-pigs was performed by histological analysis, scanning electron microscopy, and hystochemical methods, such as NADH-diaphorase and acetylcholinesterase (AChE). The round or oval shaped intramural neurons were revealed among the bundles of the smooth detrusor muscle in clusters containing a variable number of cells in the groups. In both adult control and aged animals, the ganglia were enveloped by a ganglionar capsule of connective tissue mainly composed of type I collagen fibers. The number of neurons NADH-diaphorase positives estimated in the intramural plexus was 1433±187.71 and 1107±120.67 in the adult control and aged groups, respectively. The perikaryon areas of the NADH-diaphorase neurons reactives ranged from 216.40 to 1809.30μm2 in adult control group and from 198.20 to 2096.25μm2 in aged group. The nuclear area showed an increase in aged animals. The number of AChE-positive neurons estimated in the intramural plexus was 3294.67±415μm2 in the adult control group and 1960.33±526μm2 in the aged group, showing a significant decrease in the latter group. This age-related morphological change in intramural neurons may contribute to changes in urinary bladder activities in the elderly. [Copyright &y& Elsevier]

Shinohara J, Shibata T, Shimada A, Komatsu K. The biomechanical properties of the healing periodontium of replanted rat mandibular incisors. Dent Traumatol 2004; 20: 212–221. © Blackwell Munksgaard, 2004. One of the most important aspects in tooth replantation seems to be restoration of the tooth support function of the healing periodontal ligament (PDL). We examined the support function, as measured by the mechanical properties, of the healing PDL at 7, 14, and 21 days after replantation of the left mandibular incisor in rats. From each dissected left mandible, a transverse section(650 µm in thickness) of the incisor was cut through an axis near the labial alveolar crest. Each section was intrusively loaded at a rate of 5 mm min−1, and the shear stress–strain curve for the PDL was analyzed. Mechanical measures of the healing PDL showed gradual improvement after replantation. By 21 days, the mechanical strength returned to 53% of the control value; the extensibility, to 85%; the stiffness, to 61%; and the toughness, to 52%. The healing PDL exhibited reattachment of fibers in the middle region of the PDL, and the birefringent collagen fibers appeared to have regained the functional orientation by 14 days. The ratios occupied by the birefringent collagen fibers in the tooth-related, middle, and bone-related areas of the healing PDL gradually improved and returned to 78, 51, and 48% of the respective control values by 21 days. These results suggest that the support function of the healing PDL is gradually restored and that the biomechanical restoration is closely related to the reorganization and reorientation of collagen fiber bundles in replanted rat incisors. [ABSTRACT FROM AUTHOR]

The elastic properties of the periodontal ligament have been attributed, in part, to oxytalan fibers, as no other types of elastic fibers are described there. It has been difficult to study the periodontal elastic meshwork by standard microscopic techniques because it is partially obscured by the adjacent periodontal ligament collagen fibers. Our study employed methods which either completely or partially removed mandibular molar periodontal ligament collagen fibers, exposing a previously undescribed periodontal elastic meshwork. The periodontal elastic meshwork was composed of many elastin lamellae containing both peripheral microfibrils of regular arrangement and central microfibrils of irregular arrangement, which could only be demonstrated in oxidized tissues. Peripheral, regularly arranged bundles of microfibrils resembled oxytalan fibers, which were often adherent to the border of the elastin lamella. Elastin lamellae containing irregular microfibrils resembled elaunin fibers. These fibers probably enclosed either blood vessels, nerves or collagen fiber bundles. Peripheral microfibrils attached elaunin to cementum, alveolar bone, blood vessels, and principal periodontal collagen fibers. Thus, the periodontal elastic meshwork is composed of both oxytalan and elaunin fibers. Microfibrils attach elaunin fibers to the adjacent non-elastic tissue and also form bundles which traverse the periodontal ligament space and are probably the oxytalan fibers demonstrable by light microscopic techniques. This meshwork of oxytalan and elaunin fibers probably contributes to tooth support and maintenance of periodontal homeostasis by dissipating chewing forces and maintaining patency of periodontal blood vessels. [ABSTRACT FROM AUTHOR]

Two-dimensional image by conventional optical coherence tomography (OCT) is very useful in dermatology. Recently, Fourier domain OCT (FD-OCT), which includes spectral domain OCT (SD-OCT) and swept source OCT (SS-OCT), has been developed as a new modality that produces fast and highly sensitive OCT images. These new OCTs enable real-time, video rate cross-sectional imaging and three-dimensional analysis. Moreover, polarization sensitive SD-OCT provides three dimensional information about collagen structure in the skin. Noninvasive in vivo three-dimensional analysis offers a new way to investigate the relationship between surface morphology (wrinkles, textures, and facial pores) and the internal structure of the skin. [ABSTRACT FROM AUTHOR]