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Background: The aims of this study were to determine whether arterial hypertension could affect the venous system of brain and to find out the consequent pathologic changes of cerebral veins., Methods: Thirty male Sprague-Dawley rats were divided into 2 groups: a sham-clipped group and a stroke-prone renovascular hypertensive rat group. A 2-kidney 2-clip rat model was used to induce renovascular hypertension in the hypertensive group. Systolic blood pressure was measured by tail cuff once each week. Susceptibility-weighted imaging (SWI) was performed at 12, 16, and 20 weeks after surgery. All the rats were sacrificed after the SWI examination at 20 weeks after surgery. The brains were extracted and embedded in paraffin for histologic examination. Masson trichrome staining was performed to identify venous collagenosis., Results: The sham group demonstrated less prominence of cerebral veins compared with hypertensive groups (P < .01); the hypertensive group showed significant venous collagenosis in cerebral venous walls compared with the sham group (P < .01)., Conclusions: The increased visibility of cerebral veins on SWI as a sign of venous hypertension and the thickened cerebral venous walls (venous collagenosis), which may play a role in cerebral ischemia and/or infarction, are both consequences of long-term hypertension in hypertensive rats., (Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

In this paper the mechanical response of soft collagenous tissues with regular fiber arrangement (RSCTs) is described by means of a nanoscale model and a two-step micro-macro homogenization technique. The non-linear collagen constitutive behavior is modeled at the nanoscale by a novel approach accounting for entropic mechanisms as well as stretching effects occurring in collagen molecules. Crimped fibers are reduced to equivalent straight ones at the microscale and the constitutive response of RSCTs at the macroscale is formulated by homogenizing a fiber reinforced material. This approach has been applied to different RSCTs (tendon, periodontal ligament and aortic media), resulting effective and accurate as proved by the excellent agreement with available experimental data. The model is based on few parameters, directly related to histological and morphological evidences and whose sensitivity has been widely investigated. Applications to simulation of some physiopathological mechanisms are also proposed, providing confirmation of clinical evidences and quantitative indications helpful for clinical practice., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The collagen superfamily of proteins plays a dominant role in maintaining the integrity of various tissues and also has a number of other important functions. The superfamily now includes more than 20 collagen types with altogether at least 38 distinct polypeptide chains, and more than 15 additional proteins that have collagen-like domains. Most collagens form polymeric assemblies, such as fibrils, networks and filaments, and the superfamily can be divided into several families based on these assemblies and other features. All collagens also contain noncollagenous domains, and many of these have important functions that are distinct from those of the collagen domains. Major interest has been focused on endostatin, a fragment released from type XVIII collagen, which potently inhibits angiogenesis and tumour growth. Collagen synthesis requires eight specific post-translational enzymes, some of which are attractive targets for the development of drugs to inhibit collagen accumulation in fibrotic diseases. The critical roles of collagens have been clearly illustrated by the wide spectrum of diseases caused by the more than 1,000 mutations that have thus far been identified in 22 genes for 12 out of the more than 20 collagen types. These diseases include osteogenesis imperfecta, many chondrodysplasias, several subtypes of the Ehlers-Danlos syndrome, Alport syndrome, Bethlem myopathy, certain subtypes of epidermolysis bullosa, Knobloch syndrome and also some cases of osteoporosis, arterial aneurysms, osteoarthrosis, and intervertebral disc disease. The characterization of mutations in additional collagen genes will probably add further diseases to this list. Mice with genetically engineered collagen mutations have proved valuable for defining the functions of various collagens and for studying many aspects of the related diseases.

Collagens can be divided into two groups, i.e., fibrillar and non-fibrillar collagens. Short-chain collagens, a subgroup of non-fibrillar collagens, comprises collagen type VIII and type X. These two collagen types show several similarities in structure and possibly also in function. Type VIII collagen appears to be secreted by rapidly proliferating cells. It can be found in basement membranes and may serve as a molecular bridge between different types of matrix molecules. In different tissues this collagen type may serve different functions. Stabilization of membranes, angiogenesis, and interactions with other extracellular matrix molecules. Since collagen type X is produced by hypertrophic chondrocytes, this collagen type can only be found in matrix of the hypertrophic zone of the epiphyseal growth plate cartilage. Collagen type X is probably involved in the process of mineralization, endochondral ossification, and is also proposed to play a role in angiogenesis. Collagen types VII and X may be involved in matrix and bone disorders. Their structure, function, and involvement in pathology are discussed in this review.

Collagen is a macro-molecule of polypeptide chains arranged in a triple helix. The biosynthesis and degradation of collagen require complex enzymes systems; considerable progress has been made in their understanding in recent years. Collagen is the most important connective tissue of the body and five types are present in the lower respiratory tract. Genetic disorders of collagen (e.g. the Ehlers-Danlos or Marfan's syndrome) may affect the lung. Furthermore certain pulmonary diseases such as fibrosis are associated with changes in the ratio of the different types of collagen. Collagen can no longer be dissociated from the study of tissue changes in pulmonary pathology; the aim of our study is to provide elementary data concerning this aspect of modern pneumology.

Fibroblasts derived from patients and animals presenting various heritable connective tissue disorders were investigated for the ability to retract a reconstituted collagen matrix. When seeded into gels, dermatosparactic calf and sheep fibroblasts did not exhibit the elongated shape of normal fibroblasts and did not contract the collagen lattice to the same extent as control fibroblasts. In contrast, several cell strains obtained from patients with Ehlers-Danlos syndrome type VII displayed contractile properties for collagen gels similar to controls. Delayed contraction was noted by two strains of fibroblasts from patients with Ehlers-Danlos syndrome type IV, whereas fibroblasts from patients with osteogenesis imperfecta, Marfan syndrome and cutis laxa had normal retraction properties.