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Circ Res. 2000 Oct 13;87(8):663-9.
Myocardial mechanics and collagen structure in the osteogenesis imperfecta murine (oim).
Weis SM, Emery JL, Becker KD, McBride DJ Jr, Omens JH, McCulloch AD.
Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
Because the amount and structure of type I collagen are thought to affect the mechanics of ventricular myocardium, we investigated myocardial collagen structure and passive mechanical function in the osteogenesis imperfecta murine (oim) model of pro-alpha2(I) collagen deficiency, previously shown to have less collagen and impaired biomechanics in tendon and bone. Compared with wild-type littermates, homozygous oim hearts exhibited 35% lower collagen area fraction (P:<0.05), 38% lower collagen fiber number density (P:<0.05), and 42% smaller collagen fiber diameter (P:<0.05). Compared with wild-type, oim left ventricular (LV) collagen concentration was 45% lower (P:<0.0001) and nonreducible pyridinoline cross-link concentration was 22% higher (P:<0.03). Mean LV volume during passive inflation from 0 to 30 mm Hg in isolated hearts was 1.4-fold larger for oim than wild-type (P:=NS). Uniaxial stress-strain relations in resting right ventricular papillary muscles exhibited 60% greater strains (P:<0.01), 90% higher compliance (P:=0.05), and 64% higher nonlinearity (P:<0.05) in oim. Mean opening angle, after relief of residual stresses in resting LV myocardium, was 121+/-9 degrees in oim compared with 45+/-4 degrees in wild-type (P:<0.0001). Mean myofiber angle in oim was 23+/-8 degrees greater than wild-type (P:<0.02). Decreased myocardial collagen diameter and amount in oim is associated with significantly decreased fiber and chamber stiffness despite modestly increased collagen cross-linking. Altered myofiber angles and residual stress may be beneficial adaptations to these mechanical alterations to maintain uniformity of transmural fiber strain. In addition to supporting and organizing myocytes, myocardial collagen contributes directly to ventricular stiffness at high and low loads and can influence stress-free state and myofiber architecture.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029401&dopt=Abstract
J Cell Biochem. 2000 Sep 18;80(1):139-45.
Effects of calcium and magnesium on a 41-kDa serine-dependent protease possessing collagen-cleavage activity.
Robinson JJ.
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada. johnrorgan.ucs.mun.ca
We report here the continued characterization of a 41-kDa protease expressed in the early stage of the sea urchin embryo. This protease was previously shown to possess both a gelatin-cleavage activity and an echinoderm-specific collagen-cleavage activity. In the experiments reported here, we have explored the biochemical nature of this proteolytic activity. Pepstatin A (an acidic protease inhibitor), 1,10-phenanthroline (a metalloprotease inhibitor), and E-64 (a thiol protease inhibitor) were without effect on the gelatin-cleavage activity of the 41-kDa species. Using a gelatin substrate gel zymographic assay, the serine protease inhibitors phenylmethylsulfonyl fluoride and benzamide appeared to partially inhibit gelatin-cleavage activity. This result was confirmed in a quantitative gelatin-cleavage assay using the water soluble, serine protease inhibitor [4-(2-aminoethyl)benzenesulfonylfluoride]. The biochemical character of this protease was further explored by examining the effects of calcium and magnesium, the major divalent cations present in sea water, on the gelatin-cleavage activity. Calcium and magnesium competed for binding to the 41-kDa collagenase/gelatinase, and prebound calcium was displaced by magnesium. Cleavage activity was inhibited by magnesium, and calcium protected the protease against this inhibition. These results identify calcium and magnesium as antagonistic agents that may regulate the proteolytic activity of the 41-kDa species. 2000 Wiley-Liss, Inc.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029761&dopt=Abstract
Thromb Res. 2002 Aug 15;107(3-4):141-5.
Effect of resveratrol, a natural polyphenolic compound, on platelet activation induced by endotoxin or thrombin.
Olas B, Wachowicz B, Saluk-Juszczak J, Zielinski T.
Department of General Biochemistry, Institute of Biochemistry, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland. olasiol.uni.lodz.pl
Resveratrol (3, 4', 5-trihydroxystilbene), a natural polyphenol, is found in some plants that are used in human nutrition. Grapes are a major source for resveratrol, and a significant amount can also be found in red wine. Several experimental studies have demonstrated biological properties of resveratrol, especially its anti-inflammatory, antioxidant, anti-platelet and antitumor effects. In the present study, we investigated the first step of platelet activation-platelet adhesion stimulated by lipopolysaccharide (LPS) from Proteus mirabilis (weak stimulator) and thrombin (strong activator) in the presence of resveratrol. Our studies show that endotoxin (0.3 microg/10(8) platelets), like thrombin (0.2 U/10(8) platelets), induced the adhesion of platelets (expressed as absorbance of cell attached proteins) to collagen and fibrinogen. Preincubation of washed platelets with resveratrol at physiological plasma concentrations (25-100 microg/ml, 30 min, 37 degrees C) had an inhibitory effect on adhesion of platelets to collagen after activation by LPS alone or LPS with thrombin. The strongest effect on this process was caused by resveratrol at the concentration of 100 microg/ml. Pretreatment of platelets with resveratrol (25-100 microg/ml, 30 min, 37 degrees C) had also inhibitory effects on adhesion of platelets to fibrinogen after stimulation of these cells by LPS alone or by LPS with thrombin at the same concentration. In conclusion, we suggest that resveratrol present in human diet may be an important compound responsible for the reduction of platelet adhesion and changed reactivity of blood platelets in inflammatory process. 2002 Elsevier Science Ltd.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12431480&dopt=Abstract [PubMed - in process]
J Cell Biochem. 2000 Sep 18;80(1):146-55.
Type V collagen regulates the assembly of collagen fibrils in cultures of bovine vascular smooth muscle cells.
Kypreos KE, Birk D, Trinkaus-Randall V, Hartmann DJ, Sonenshein GE.
Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
Vascular smooth muscle cells (SMCs), the major cellular constituent of the medial layer of an artery, synthesize the majority of connective tissue proteins, including fibrillar collagen types I, III, and V/XI. Proper collagen synthesis and deposition, which are important for the integrity of the arterial wall, require the antioxidant vitamin C. Vitamin C serves as cofactor for the enzymes prolyl and lysyl hydroxylase, which are responsible for the proper hydroxylation of collagen. Here, the role of type V collagen in the assembly of collagen fibrils in the extracellular matrix (ECM) of cultured vascular SMCs was investigated. Treatment of SMCs with vitamin C resulted in a dramatic induction in the levels of the cell-layer associated pepsin-resistant type V collagen, whereas only a minor induction in the levels of types I and III collagen was detected. Of note, the deposition of type V collagen was accompanied by the formation of striated collagen fibrils in the ECM. Immunohistochemistry demonstrated that type V collagen, but not type I collagen, became masked as collagen fibrils matured. Furthermore, the relative ratio of type V to type I collagen decreased as the ECM matured as a function of days in culture, and this decrease was accompanied by an increase in the diameter of collagen fibrils. Together these results suggest that the masking of type V collagen is caused by its internalization on continuous deposition of type I collagen on the exterior of the fibril. Furthermore, they suggest that type V collagen acts as framework for the initial assembly of collagen molecules into heterotypic fibrils, regulating the diameter and architecture of these fibrils. 2000 Wiley-Liss, Inc.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029762&dopt=Abstract
Breast Cancer. 2000;7(3):221-30.
Cytokines facilitate chemotactic motility of breast carcinoma cells.
Arihiro K, Oda H, Kaneko M, Inai K.
Department of Pathology, Kure National Hospital/Chugoku District Cancer Center, 3-1 Aoyama-cho, Kure, Hiroshima 737-0023, Japan.
BACKGROUND: Both growth and motility of various tumor cells have been shown to be influenced by surrounding cells such as lymphocytes, histiocytes and fibroblasts through various cytokines, growth factors and extracellular matrices. The role of cytokines and extracellular matrices produced by lymphocytes, histiocytes and fibroblasts on migration and invasion of breast carcinoma cells has not been fully investigated METHODS: We investigated the effect of hepatocyte growth factor (HGF), interleukin (IL)-6, IL-8, IL-11, soluble type IV collagen and soluble laminin on the migration of 3 human breast carcinoma cell lines, MDA-MB-231, MCF-7 and T-47D, using a cell culture insert and a biocoat matrigel invasion chamber to assess migration across a matrigel-coated polyethylene telephtalate membrane. RESULTS: HGF, IL-6, IL-11 and IL-8 induced significant migration of MDA-MB-231 cells depending on the dose of each cytokine. However, type IV collagen and laminin inhibited migration of MDA-MB-231 cells. In contrast, IL-8 inhibited migration of MCF-7 cells and IL-6 induced significant migration of T-47D cells, while no other cytokine or extracellular matrix induced significant migration of MCF-7 and T-47D cells. Only HGF induced significant invasion of MDA-MB-231 cells depending on the dose. MCF-7 and T-47D cells did not invade in response to any of the cytokines and extracellular matrices tested. CONCLUSIONS: These results suggest the possibility that the potency of chemotaxis or chemoinvasion differs according to the breast carcinoma cell line and that various cytokines and extracellular matrices secreted by lymphocytes, histiocytes and fibroblasts in the stroma of breast carcinoma can affect the invasion of breast carcinoma cells.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029802&dopt=Abstract
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