Abnormalities-in-the-structure-andor-processing-of-type-I-collagen-cause-osteogenesis-imperfecta-and-result-in-bone-fragility-abnormal-bone-growth-and-short-stature-b
Type I collagen is expressed in the growth plate but the mechanisms by which abnormalities in collagen I contribute to growth plate dysfunction and growth retardation are unknown. The non-collagenous domain (NC1) of type X collagen (CXM) is released from the hypertrophic zone of active growth plates and is a marker for new endochondral bone formation. Serum CXM levels are strongly correlated with the rate of growth in healthy children. We hypothesized that CXM levels in children with OI would be abnormal when compared to normally growing children. Using participants from the Brittle Bone Disease Consortium Natural History Study we analyzed the distribution of CXM over the ages of 8 months to 40 years in 187 subjects with OI (89 type I and 98 types III/IV) as well as analyzed the relationship between growth velocity and CXM levels in a subset of 100 children <16 years old with OI (44 type I and 56 types III/IV). CXM levels in both control and OI children demonstrated a similar pattern of variation by age with higher levels in early life and puberty followed by a post-pubertal drop.
However, there was greater variability within the OI cohort and the relationship with growth velocity was weaker. The ratio of CXM level to growth velocity was elevated in children with type III/IV OI compared to controls. These results suggest that the relationship between hypertrophic zone function and the end point of skeletal growth is disrupted in OI.Endothelial cells secrete a novel collagen type in vitro independently of prolyl Endothelial cells from bovine aorta, vena cava, and cornea secrete a novel collagen in vitro (Sage et al., 1980). API (EC), which is sensitive to pepsin and to several neutral proteases, exhibited an additional unusual property in its mode of secretion. In the absence of added sodium ascorbate, EC was secreted by both aortic and corneal endothelial cells at levels which were very similar to those observed in cultures supplemented with this vitamin.
In contrast, the secretion of type III procollagen, which normally constitutes 75-80% of collagenous protein in the culture medium, was significantly decreased in ascorbate-deficient cultures. Incubation of aortic endothelial cells with alpha, alpha'-dipyridyl, an inhibitor of prolyl and lysyl hydroxylases, reduced the extent of prolyl hydroxylation in total culture medium protein by 98% but also did not affect the secretion of EC. The secretion of EC by endothelial cells appears to be independent of a requirement for prolyl hydroxylation. This property differs markedly from the secretory characteristics of the interstitial procollagens and more closely resembles that described for type IV (basement membrane) procollagen.Imaging Fibrosis and Separating Collagens using Second Harmonic Generation and Phasor Approach to Fluorescence Lifetime Imaging.University of California Irvine, California.In this paper we have used second harmonic generation (SHG) and phasor approach to auto fluorescence lifetime imaging (FLIM) to obtain fingerprints of different collagens and then used these fingerprints to observe bone marrow fibrosis in the mouse femur.
This is a label free approach towards fast automatable detection of fibrosis in tissue samples. FLIM has previously been used as a method of contrast in different tissues and in this paper phasor approach to FLIM is used to separate collagen I from collagen III, the markers of fibrosis, the largest groups of disorders that are often without any effective therapy. Often characterized by an increase in collagen content of the corresponding tissue, the samples are usually visualized by histochemical staining, which is pathologist dependent and cannot be automated.Characterization of a unique collagen ous fraction from limited pepsin digests of human placental tissue: molecular organization of the native aggregate.Precise ultrastructural localization of in vivo deposited IgG antibodies in fresh perilesional skin of patients with bullous pemphigoid.Bullous pemphigoid (BP) is a blistering skin disease in which the patient develops autoantibodies to the epidermal basement membrane zone. Using postembedding immunogold electron microscopy, we previously demonstrated that autoantibodies against the 230-kDa BP antigen (BPAG1) bind to the intracellular hemidesmosomal component of normal skin, whereas those against the 180-kDa BP antigen (BPAG2) bind only along the plasma membrane of hemidesmosomes.
The purpose of the present study was to elucidate the precise localization of the in vivo deposited IgG antibodies in fresh perilesional skin of patients with BP. Samples of fresh perilesional skin were obtained from three patients with BP whose sera reacted only with BPAG1, only with BPAG2, and with both BPAG1 and BPAG2 upon immunoblotting using epidermal extracts.
