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Tissue Calcification (tissue + calcification)
Selected AbstractsThe Spectrum of Myositis Ossiticans in HaemophiliaHAEMOPHILIA, Issue 2 2004G. V. Massey Summary., Myositis ossificans (MO) refers to non-neoplastic heterotopic soft tissue ossification that can have several aetiologies. Broadly it can be classified into three categories based on aetiology [1]. MO traumatica, the most common form occurs secondary to acute or chronic trauma. MO can also be associated with neurological disorders and in rare cases is congenital. The latter (progressive MO) is a genetic disorder in which congenital osseous abnormalities are associated with progressive soft tissue calcification. Despite an increased tendency to soft tissue bleeds, MO has been rarely reported in haemophilia. We treated three adolescents with haemophilia and MO of varying degrees of severity and outcome. [source] Novel Inhibitors of Alkaline Phosphatase Suppress Vascular Smooth Muscle Cell Calcification,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2007Sonoko Narisawa Abstract We report three novel inhibitors of the physiological pyrophosphatase activity of alkaline phosphatase and show that these compounds are capable of reducing calcification in two models of vascular calcification (i.e., they suppress in vitro calcification by cultured Enpp1,/, VSMCs and they inhibit the increased pyrophosphatase activity in a rat aortic model). Introduction: Genetic ablation of tissue-nonspecific alkaline phosphatase (TNALP) leads to accumulation of the calcification inhibitor inorganic pyrophosphate (PPi). TNALP deficiency ameliorates the hypermineralization phenotype in Enpp1,/, and ank/ank mice, two models of osteoarthritis and soft tissue calcification. We surmised that the pharmacological inhibition of TNALP pyrophosphatase activity could be used to prevent/suppress vascular calcification. Materials and Methods: Comprehensive chemical libraries were screened to identify novel drug-like compounds that could inhibit TNALP pyrophosphatase function at physiological pH. We used these novel compounds to block calcification by cultured vascular smooth muscle cells (VSMCs) and to inhibit the upregulated pyrophosphatase activity in a rat aortic calcification model. Results: Using VSMC cultures, we determined that Enpp1,/, and ank/ank VSMCs express higher TNALP levels and enhanced in vitro calcification compared with wildtype cells. By high-throughput screening, three novel compounds, 5361418, 5923412, and 5804079, were identified that inhibit TNALP pyrophosphatase function through an uncompetitive mechanism, with high affinity and specificity when measured at both pH 9.8 and 7.5. These compounds were shown to reduce the calcification by Enpp1,/, VSMCs. Furthermore, using an ex vivo rat whole aorta PPi hydrolysis assay, we showed that pyrophosphatase activity was inhibited by all three lead compounds, with compound 5804079 being the most potent at pH 7.5. Conclusions: We conclude that TNALP is a druggable target for the treatment and/or prevention of ectopic calcification. The lead compounds identified in this study will serve as scaffolds for medicinal chemistry efforts to develop drugs for the treatment of soft tissue calcification. [source] Mechanobiological response of tendon stem cells: Implications of tendon homeostasis and pathogenesis of tendinopathyJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2010Jianying Zhang Abstract Tendons are constantly subjected to mechanical loading in vivo. Recently, stem cells were identified in human, mouse, and rabbit tendons, but the mechanobiological responses of tendon stem cells (TSCs) are still undefined. Using an in vitro system capable of mimicking in vivo loading conditions, it was determined that mechanical stretching increased TSC proliferation in a stretching magnitude-dependent manner. Moreover, low mechanical stretching at 4% ("clamp-to-clamp" engineering strain) promoted differentiation of TSCs into tenocytes, whereas large stretching at 8% induced differentiation of some TSCs into adipogenic, chondrogenic, and osteogenic lineages, as indicated by upregulated expression of marker genes for adipocytes, chondrocytes, and osteocytes. Thus, low mechanical stretching may be beneficial to tendons by enabling differentiation of TSCs into tenocytes to maintain tendon homeostasis. However, large mechanical loading may be detrimental, as it directs differentiation of TSCs into non-tenocytes in tendons, thus resulting in lipid accumulation, mucoid formation, and tissue calcification, which are typical features of tendinopathy at later stages. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:639,643, 2010 [source] Delayed changes in T1 -weighted signal intensity in a rat model of 15-minute transient focal ischemia studied by magnetic resonance imaging/spectroscopy and synchrotron radiation X-ray fluorescenceMAGNETIC RESONANCE IN MEDICINE, Issue 3 2006Xuxia Wang Abstract Previous studies have found that rats subjected to 15-min transient middle cerebral artery occlusion (MCAO) show neurodegeneration in the dorsolateral striatum only, and the resulting striatal lesion is associated with increased T1 -weighted (T1W) signal intensity (SI) and decreased T2 -weighted (T2W) SI at 2,8 weeks after the initial ischemia. It has been shown that the delayed increase in T1W SI in the ischemic region is associated with deposition of paramagnetic manganese ions. However, it has been suggested that other mechanisms, such as tissue calcification and lipid accumulation, also contribute to the relaxation time changes. To clarify this issue, we measured changes in relaxation times, lipid accumulation, and elemental distributions in the brain of rats subjected to 15-min MCAO using MRI, in vivo 1H MR spectroscopy (MRS), and synchrotron radiation X-ray fluorescence (SRXRF). The results show that a delayed (2 weeks after ischemia) increase in T1W SI in the ischemic striatum is associated with significant increases in manganese, calcium, and iron, but without evident accumulation of MRS-visible lipids or hydroxyapatite precipitation. It was also found that 15-min MCAO results in acutely reduced N-acetylaspartate (NAA)/creatine (Cr) ratio in the ipsilateral striatum, which recovers to the control level at 2 weeks after ischemia. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Calcinosis circumscripta following an injection of proligestone in a Burmese catAUSTRALIAN VETERINARY JOURNAL, Issue 3 2001CR OBRIEN A 9-month-old speyed Burmese cat was presented with a cutaneous lesion in the dorsal thoracolumbar region. The lesion was characterised by alopecia and whitish deposits within the subcutis and had occurred at the site of a previous progestogen injection (Covinan; Intervet). Excisional biopsy confirmed the diagnosis of calcinosis circumscripta. Recovery of the cat following surgical excision was excellent, with no recurrence of the lesion detected 12 months later. The classification of tissue calcification and the proposed aetiology of calcinosis circumscripta is reviewed. It is concluded that further work is required to determine any link between subcutaneous injections, especially of progesto-gens, and calcinosis circumscripta. [source] Calciphylaxis in a patient with alcoholic liver disease in the absence of renal failureCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 1 2003S. P. R. Lim Summary Calciphylaxis is a rare, potentially life-threatening syndrome characterized by progressive microvascular and superficial soft tissue calcification, usually seen in patients with chronic renal failure. We describe an unusual case of calciphylaxis in a patient with alcoholic liver disease and normal renal function who responded well to conservative wound care. [source] Phytate prevents tissue calcifications in female ratsBIOFACTORS, Issue 3 2000F. Grases The AIN-76 A, a purified rodent diet, has a propensity to cause kidney calcifications in female rats which is not observed with non-purified rodent diets, suggesting a nutritional factor that avoids these calcifications. One candidate is phytate, which inhibits crystallisation of calcium salts and is practically absent in purified diets. Therefore, the effects on calcification of kidney tissue of phytate addition to the AIN-76 A diet using female Wistar rats were studied. The rats were assigned to three groups: AIN-76 A, AIN-76 A + 1% phytate and standard nonpurified chow. Urinary phytate of the AIN-76 A fed group was undetectable. Urinary phytate of AIN-76 A + 1% phytate and standard fed groups did not differ and was significantly higher than in the AIN-76 A group. The concentrations of calcium and phosporus in kidneys were greater in the AIN-76 A group than in AIN-76 A + 1% phytate and standard groups. Only rats of the AIN-76 A group displayed mineral deposits at the corticomedullary junction. These findings demonstrated that the absence of phytate in the AIN-76 A diet is one of the causes of renal calcification in female rats. [source] | |||||||||||||