Vitamin D3 Deficiency Differentially Affects Functional and Disease Outcomes in the G93A Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease characterized by motor neuron death in the central nervous system. Vitamin D supplementation increases antioxidant activity, reduces inflammation and improves motor neuron survival. We have previously demonstrated that vitamin D3 supplementation at 10× the adequate intake improves functional outcomes in a mouse model of ALS

UNDERSTANDING THE BIOMECHANICS OF TENDON FIBROCARTILAGES

A direct analogy with the function of large proteoglycans in articular cartilage has led to the assumption that the presence of such components in tendon fibrocartilages is a major factor enabling these structures to resist pressure. However, the association of collagen fibrils in bundles and their tensional state as verified through the existence of crimp under polarized light in tendon fibrocartilage raises doubts as to whether the large proteoglycans are kept under osmotic pressure, which is an essential condition for their physiological role in articular cartilage. This suggests that tendon fibrocartilage has distinct mechanisms to resist pressure. In tendon fibrocartilages, the compressive forces must be transferred to the inextensible collagen fibers which lie in many directions in different planes, before reaching the parallel fibers of the tension region. In this sense, the large proteoglycans are likely to have the function of providing a viscous and cohesive environment in which collagen fibers could get stretched to reinforce the tissue.172329329

THE UNIQUE FIBRILLAR ARRANGEMENT OF THE BULLFROG PRESSURE-BEARING TENDON AS AN INDICATIVE OF GREAT FUNCTIONAL DEFORMABILITY

The fiber distribution and ultrastructure in the plantaris longus pressure-bearing tendon of the bullfrog were investigated. The tension region of the tendon showed a predominant parallel distribution of collagen fibers, but three main zones with different crimp parameters were identified with the use of the polarizing microscope. The compression region showed collagen fibers with aspects of disaggregation and were composed of disperse and undulating fibrils, These collagen fibers establish a three-dimensional network but showed a preferential distribution in planes disposed perpendicularly to the tendon's main axis. It is assumed that the convoluted and disaggregated collagen fibers must be distended before exerting any reinforcement on the tissue and that this only occurs after a great deformation of the tendon. Groups of 5-6 fibrils not associated in fibers are also dispersed in the compression region. The tissue is assumed to have a highly viscous fluid nature allowing for the deformation needed for collagen fibrils to reinforce the tendon structure. The convoluted and crimped structure of collagen fibers would be especially useful when the tendon is submitted to the sudden and strong mechanical loading expected to occur during jumping and to provide the tendon with the capacity of great functional deformability necessary for the high amplitude of feet movements attained on jumping and swimming.821596

CHITIN MOLECULAR ORDER IN THE CHITINOUS TENDON OF THE GRASSHOPPER, SPHARAGENON-BOLLI

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Basement membrane associated changes in the rat ventral prostate following castration

This study focuses on the basement membrane associated modifications that take place after androgen blockade, by studying some of its main components, through histochemical, immunohistochemical and Western blotting tests, and its ultrastructural aspects. It was demonstrated that laminin and collagen type IV remain associated with a thickened basement membrane and that there is an apparent increase in heparan sulfate content 21 days after castration. Ultrastructurally, basal lamina appeared extensively folded and pleated. It was also observed that detachment of epithelial cells is not dependent of basal lamina degradation and that the free basal lamina surfaces are folded by the action of adjacent cells. We have also observed some aspects of smooth muscle cell degeneration and death, that lead to modifications of the associated basal lamina. In this case, residual basal lamina also shows extensive folding. The results suggested that degradation of excess basement membrane does not occur or is a very slow process within the period examined, and that basement membrane is left re-organized but ultrastructurally and compositionally unaffected. (C) 1996 Academic Press Limited.201280981

STRUCTURE AND HISTOCHEMISTRY OF A PRESSURE-BEARING TENDON OF THE FROG

The plantaris longus tendon of the bullfrog Rana catesbeiana has been structurally and histochemically characterized. The tendon has been shown to wrap around the distal tibio-fibular joint, extending into an aponeurosis. The region under the joint exhibits a large cartilaginous pad. In contrast to the mammalian flexor digitorum profundus tendons, the compression region of the frog tendon is not typically fibrocartilaginous but presents a unique arrangement of convoluted collagen bundles and fibers associated with a large amount of glycosaminoglycans. The sulfated nature of the glycosaminoglycans in the compressed region was determined through enzyme susceptibility as well as through CEC procedures. Cells of the modified zone exhibited morphological variation, from fibroblastic to condrocyte-like. Polarized light analysis revealed an intricate array of collagen bundles which crossed the tendon in different directions and connected the tension and compression regions. The ability of the tendon to resist compressive forces is assumed to be due to the large amount of glycosaminoglycans in the modified region as well as to the complex arrangement of collagen bundles in the tendon as a whole.176216117

THE ELASTIC SYSTEM OF A PRESSURE-BEARING TENDON OF THE BULLFROG RANA-CATESBEIANA

Elastic system components have been described in the pressure-bearing tendon of the bullfrog, Rana catesbeiana, as a result of histochemical tests and transmission and scanning electron microscopy. The tension region was shown to possess microfibril bundles, some of which exhibited central deposits of amorphous material. The use of ANS-butanol plus fluorescence microscopy enormously facilitated the identification of elastic system components in both tension and compression regions of the frog tendon. The compression region exhibited pre-elastic and mature elastic fibers, which were shown to be associated with the surface of the convoluted collagen bundles. Thin fibrils were observed in the compression region after ANS treatment. The visceral paratenon had an increased number of elastic fibers located between the collagen bundles and close to the cells. Congo red plus polarization microscopy failed to impart birefringence to the elastic fibers, but they could be identified by their intense staining and isotropic appearence against the bright background of birefringent collagen fibers. SEM demonstrated the three-dimensional aspects of the elastic fibers. They are composed of fibrils of a sinuous nature. The use of rutheniun red in the fixative allowed for the observation of an intimate association of proteoglycan granules with the microfibril bundles. The elastic components identified in the pressure-bearing tendon are assumed to be important for the tissue supramolecular organization, especially in the maintenance of the convoluted state of the collagen fibers in the compression region and their crimp morphology in the tension region. The elastic system must also play an important role in the restoration of the resting shape of the tendon after the deformation achieved during mechanical stimulation.177539740

Fluorescence and confocal laser scanning microscopy imaging of elastic fibers in hematoxylin-eosin stained sections

We have studied the possibility of associating fluorescence microscopy and hematoxylin-eosin staining for the identification of elastic fibers in elastin-rich tissues. Elastic fibers and elastic laminae were consistently identified by the proposed procedure, which revealed itself to be easy and useful for the determination of such structures and their distribution. The fluorescence properties of stained elastic fibers are due to eosin staining as revealed by fluorescence analysis of the dye in solution, with no or only minor contribution by the elastin autofluorescence. The main advantage of this technique resides in the possibility of studying the distribution of elastic fibers in file material without further sectioning and staining. The use of the confocal laser scanning microscope greatly improved the resolution and selectivity of imaging elastic fibers in different tissues. The determination of the three-dimensional distribution and structure of elastic fiber and laminae using the confocal laser scanning microscope was evaluated and also produced excellent results.106658759

Polarized microscopy study of an antennal sensillum of Triatoma infestans: An ordered distribution of chitin fibrils and associated components

Aspects of the molecular organization of the antennal sensilla trichodea of Triatoma infestans have been investigated with the use of both polarization and scanning electron microscopy. The sensilla have a smooth surface with minute bulbs on the tapered end. They showed strong positive birefringence, irrespective of the refractive index of the imbibing medium. The plotting of a form birefringence (FB) curve for native material showed slight increases in the retardation values with increases of the refractive index and at least 2 inflection points. On the other hand a FB curve constructed for alkali-treated structures reveals higher values for the form birefringence and slight decreases in retardation values with raising refractive index. These results demonstrate that chitin fibrils are preferentially aligned with the sensilla long axis. Interestingly, the alkali treatment introduced no alterations in the retardation values measured at n = 1.435, which corresponds to the intrinsic birefringence of chitin. Tt is suggested that components removed by alkali-treatment have electronic transitions disposed perpendicularly to the chitin filaments and that the ill definition of the form birefringence curve of chitin is associated with the incomplete removal of chitin-associated components, which keep chitin fibrils apart from but strongly bound to each other rn addition, it is apparent from the results that cross-linking in a system with a parallel away of the chitin fibrils occurs predominantly perpendicular to the chitin fibrils.3191333

Collagen type VI is a component of the extracellular matrix microfibril network of the prostatic stroma

Stroma-epithelium relationships are of great relevance in prostatic morphogenesis and physiology, However, little knowledge exists about either stromal cells or extracellular matrix composition and arrangement in this system, Ultrastructural analysis revealed the existence of a microfibrillar system which occupies large areas of the rat prostatic stroma, In this work, we have applied immunocytochemistry and an ATP treatment for the ultrastructural identification of collagen type VI microfibrils, aiming at examining its participation in the prostatic microfibrillar network. Immunocytochemistry was also extended to a human case of prostatic nodular hyperplasia, Both methods succeeded in identifying collagen type VI in the rat ventral prostate, Collagen type VI is evenly distributed throughout the stroma but mainly associated with the basal lamina, collagen fibrils, and around the stromal cells, The use of ATP treatment allowed for the discrimination between collagen type VI and elastin-associated microfibrils, and demonstrated that these two classes of microfibrils establish an extended, mixed, and open network. The same aspects of association with the basal lamina, with stromal cells (particularly with smooth muscle cells), and with fibrillar components of the stroma were observed in the human tissue, We suggest that the collagen type VI and elastin-associated microfibril system may be involved in the control of some aspects of cellular behavior and may also play a structural role, maintaining the organ integrity after the deformations occurring under smooth muscle contraction.29216317