Biomechanical Characteristics of Collagen Fibrils of Human Free Gingival Tissues- Atomic Force Microscope Study

@#The information of biomechanical properties is crucial in the study of biological tissue and its clinical relevance. 3mm x 3mm free gingival human tissues was taken using disposable punch biopsy (Accu sharp blade, India) and stored in 0°C Freezer. The sample was sectioned to a thickness of 10μm using high profile microtome blade (Leica 818, Germany) and cryostat (Leica CM1850UV, United Kingdom). The sample was analysed using Atomic Force Microscope (Nanowizard® 3, JPK Instruments, Germany) at room atmosphere. The collagen fibrils of the free gingival tissues appeared to be stacked in basket weave like structure. The mean value of free gingival collagen fibrils width and the length of D-band were 106.71±11.18nm and 65.82 ± 3.04nm respectively. The Young’s modulus of collagen fibrils for human free gingival tissue at overlap region was 212.88 ± 242.58 MPa, whereas at the gap region was 207.00 ± 230.71 MPa. Within the limitation of the study, the collagen fibrils appeared to be stacked in basket weave-like structure. The length and width of the collagen fibril were similar to the values investigated using other techniques. There was significant linear relationship between Young’s modulus of overlap and gap regions.

Changes of scleral structures and biomechanical properties in the process of sclera post embryonic development / 医用生物力学

Objective To investigate the changes of morphological structures and biomechanical properties of scleral tissues in rabbits at different month ages. Methods The eyeballs of 1, 2 and 3 month-old New Zealand white rabbits were obtained for measuring the diameter and axial length, and the thickness of scleral tissues. Part of the scleral tissues was used to observe scleral structures with HE staining, some other part was used to observe collagen fibrils by electron microscope, and the left part were cut into strips and used to test the elastic modulus of the sclera on Instron 5544 system. Results The diameter, axial length of eyeballs and the thickness of the sclera were increased with month age. The elastic modulus of scleral tissues was also increased with month age. The numbers of scleral fibroblasts were decreased and the numbers of fiber bundles were increased with month age. The diameters of collagen fibrils were increased with month age. Conclusions In the post-embryonic stages, the structures of eyeball and sclera are changed continually, with growing numbers of thicker collagen fibers, and the biomechanical properties of scleral tissues are improved correspondingly. The mechanism of post-embryonic development in sclera is further explained in the study, which can provide theoretical guidance for prevention of sclera-related diseases.

Quantification of left ventricular myocardial collagen system in children, young adults, and the elderly / Cuantificación del sistema de colágeno del ventrículo izquierdo del miocardio en niños, adultos jóvenes y ancianos

Studies on the collagen system of the human myocardium are still limited compared to those on small laboratory animals. The aim of this work was to observe the collagen tissue of the myocardium of the human heart as a function of age. The types of collagen, as well as the density of collagen tissue and the diameter of collagen fibrils, were examined. Fragments of the left ventricular wall from 15 hearts, 5 from children, 5 from young adults, and 5 from elderly individuals, were analyzed by using the Picrosirius-polarization method and by transmission electron microscopy (TEM). The results showed the presence of collagen type III and collagen type I, both in the endomysium and perimysium of the 3 groups studied. Measurements of collagen content in myocardial tissue displayed that both endomysial and perimysial collagen increase in number and thickness in the adult and elderly. These histochemical results coincided with the observations obtained with the electron microscope in showing an increase in the number of collagen fibrils with a large diameter in the adult and elderly hearts. The present results on cardiac collagen may be important for assessing the pathogenesis of several cardiopathies in the hearts of children, young adults, and the elderly.

Los estudios sobre el colágeno del miocardio humano son aún escasos en comparación con los hechos en pequeños animales de laboratorio. El objetivo de este trabajo fue cuantificar el tejido colágeno del miocardio del corazón humano en función de la edad. Se estudiaron los tipos de colágeno, su densidad y el diámetro de las fibrillas de colágeno. Para esto se utilizaron fragmentos de la pared del ventrículo izquierdo de 15 corazones, cinco de niños, cinco de adultos jóvenes y 5 de personas de edad avanzada. Las muestras se analizaron mediante el método de Picrosirius-polarización y por microscopía electrónica de transmisión (MET). Los resultados mostraron la presencia de colágeno tipo III y de tipo I, tanto en el endomisio como en el perimisio de los tres grupos estudiados. Además, aumenta el colágeno tanto en el endomisio como en el perimísio, así como su número y grosor a medida que aumenta la edad. Los resultados histoquímicos coincidieron con las observaciones obtenidas con el microscopio electrónico, en las que se observa un aumento en el número de fibrillas de colágeno de gran diámetro en los corazones de los adultos y los ancianos. Estos resultados podrían ser importantes para la evaluación de la patogénesis de varias cardiopatías en los corazones de niños, jóvenes y ancianos.

Effects of Mitomycin C on Scleral Collagen Fibrils According to Atomic Force Microscopy

PURPOSE: To investigate the effects of mitomycin C on the scleral collagen surfaces using atomic force microscopy (AFM). METHODS: Two non-contact mode AFM machines were used to observe changes in the morphological characteristics of human scleral surfaces before and after one, three, and five minutes of 0.02% mitomycin C application. Based on AFM topography and deflection images of the collagen fibril, the morphological characteristics of scleral fibrils including the fibril diameter and D-period were measured using the line profile. RESULTS: The sclera collagen fibril treated with 0.02% mitomycin C for one minute did not show any significant increases in mean fibril diameter (155.04 +/- 17.46 nm) or mean D-periodicity (70.02 +/- 3.33 nm), compared to those of the control group. However, the scleral collagen fibrils treated with 0.02% mitomycin C for three and five minutes showed significant increases in mean fibril diameter (182.33 +/- 16.33 nm, 199.20 +/- 12.40 nm, respectively) and mean D-periodicity (70.27 +/- 13.66 nm, 72.75 +/- 19.32 nm, respectively), compared to those of the control group. CONCLUSIONS: The present study examined the structural changes in the scleral collagen fibrils before and after mitomycin C application according to atomic force microscopy. The results indirectly suggest that three or more minutes of 0.02% mitomycin C application affects the morphology of scleral collagen.

Morphological features of Cyclosprin A-induced Gingival Hyperplasia / 대한치주과학회지

Cyclosporin A(CsA) is now widely used to treat organ transplant recipients. But CsA has various short-and long-term side effects. Especially, gingival hyperplasia is not easy to resolve since its nature is still unknown. This study discusses the pathogenesis of CsA-induced gingival hyperplasia on the basis of data obtained from light and electron microscopic studies of biopsis from patients on CsA treatment after kidney transplantation. Light microscopically, the multilayered squamous epithelium showed an irregular surface of parakeratosis and deep invaginations in the subepithelial tissue. At lamina propria, we observed bundles of irregularly arranged collagen fiber, some fibroblasts, numerous capillary vessels and a large diffuse infiltration of plasma cells. Ultrastructurally, many fibroblasts, collagen fibers, collagen fibrils were present in lamina propria. On the basis of the data collected, we propose that the morphological features of the dimensional increase in gingival tissue associated with CsA treatment in kidney transplant patients may be considered proliferative fibroblasts, collagen fibers, collagen fibrils in lamina propria.

Ultrastructual analysis of the fibrous layer of condyle in the rat temporomandibular joint with ageing

THE MORPHOLOGICAL OBSERVATIONS AND BONE HISTOMOPHOMETRIC STUDY OF THE CHICKEN EMBRYO FEMUR IN EXPERIMENTAL FLUOROSIS / 解剖学报

The femur of chicken embryo in experimental fluorosis was observed under light and electron microscope, and studied by bone histomorphometric method. The results showed that most of osteoblasts were cuboid and crowded together on the surface of bone trabecula in experimental group. The osteoid was increased and mineralized bone was diminished. The bone reformation indexes were higher significantly and the bone resorption indexes did not show differences between the two groups. The cross striations of type Ⅰ collagen fibrils in osteoid layers of experimental group were indistinct and bone lamella were jumble array. Our results suggest that though fluoride has a stimulating action on the embryonic osteoblasts and enhanced the bone formation, the osteoblasts produced abnormal collagen fibrils which caused disorder of osteoid mineralization and led to osteomalacia.