Subcutaneous Calcification

Juvenile dermatomyositis (JDM) is perhaps the most uniform, in terms of clinical and histopathological features, of the whole PM/DM disease complex. Presentation may be before 5 years of age with peak incidence between 8 and 12 years. The disease may remit and recur until well into young adult life. The skin lesions include a facial rash in butterfly distribution across nose and cheeks. Erythematous skin changes are seen over extensor surfaces of joints, especially knees, knuckles and elbows. Muscle involvement is generally evident some time later and takes the form of weakness and stiffness, particularly affecting shoulder and pelvic musculature. Proximal muscles are often worse affected than distal muscles and extensors worse than flexors. In the absence of prompt and effective treatment contractures may occur at elbows, ankles, knees, and hips. Subcutaneous calcification and skin ulceration may be found calcification of deeper-lying connective tissue may be apparent on X-ray. 

Another aluminum effect which appears to be age-related is skeletal toxicity. Increased carpal joint width, suggestive of poor bone calcification, was observed in immature rabbits receiving 20 subcutaneous doses of aluminum lactate, but was not seen in neonatal or adult rabbits (Yokel 1987). 

Hyperphosphatemia complicated by calcification of subcutaneous arteries and skin infarcts has been reported in a patient with sepsis who received an unintended excess... 

Levy RJ, Schoen FJ, Sherman FS, et al. 1986. Calcification of subcutaneously implanted Type I collagen sponges Effects of fonnaldehyde and glutaraldehyde pretreatments. Am J Pathol 122 71-82. 

To the best of our knowledge, only a few studies have attempted to prevent the calcification of HEMA-based hydrogels. It has been reported that introduction of carboxylate anions can either prevent or enhance calcification. Cemy et al. (21) found that copolymers of HEMA with 4 wt% methaciylic acid (MAAc) did not calcify under subcutaneous implantation in a rat for 14 months. A similar result was also observed after the implantation of HEMA/MAAc copolymers in the animal urinary tract (22). Other studies carried out in vitro showed that the presence of carboxylate anions significantly reduced the deposition of calcium phosphate (23) and calcium oxalate (24) on acrylic polymers and certain biopolymers. These findings obviously suggest an inhibitory effect of carboxylate anions on calcification. However, by contrast,... 

The method used for preparation of the PHEMA hydrogels was described in an earlier report (33). Fully hydrated samples equilibrated at room temperature were immersed in Millipore water at 37 0.5 °C for at least 2 weeks before calcification experiments commenced. The incorporation of citric acid into PHEMA was performed by the swelling equilibrium partition method using a 2.5 M citric acid solution. Prior to incubation in SBF or subcutaneous implantation of the hydrogels in rats, the citric acid-equilibrated gels were kept in Millipore water at 37 0.5 °C for one week. The hydrogels were sterilized by autoclaving for 20 min before implantation in the rats. 

It has been demonstrated that the release of citric acid from PHEMA hydrogels hinders the formation of calcium phosphates, especially hydroxyapatites. Because of this inhibitory effect, the calcium phosphate phases formed during in vitro calcification were mainly present as non-apatite phases, possibly MCPM and DCPD. The porous morphology of the outer surface of the spherical calcium phosphate deposits could be due to the dissolution of precipitates in the presence of citric acid. The results obtained after subcutaneous implantation ofPHEMA and PHEMA containing citric acid in rats confirmed the resistance of PHEMA-citric acid to calcification. The calcium phosphate deposits which formed in vivo consisted mainly of Ca2+ and OH deficient hydroxyapatites. However, it is not yet known whether or not the differences between the calcium phosphate phases found in vivo and in vitro arise from the presence of proteins/peptides in the in vivo calcifying medium. 

Ectopic calcifications in the blood vessels, brain, subcutaneous tissue, muscles, and cartilage (calcium phosphate is an insoluble salt) (see Figure 75). 

Jorge-Herrero E, Tumay J, Calero P, et al. Calcification and identification of metallopro-teinases in bovine pericardium after subcutaneous implantation in rats. J Mater Sci Mater Med 2001 12 1013-7. 

Some other examples of animal models that are used in biotextile retrieval studies include implanting hernia repair meshes in the abdomen of piglets and mitral valve replacement in juvenile sheep or calves, and subcutaneous implants of valve materials in young rats for in vivo biocompatibility and calcification studies. 

The ectopic calcification in the basal ganglia and in the subcutaneous tissues that is occasionally found in patients with hypo- or pseudohypoparathyroidism is difficult to explain. And it is not known why cataracts develop in both hypo- and pseudohypoparathyroidism. Mental retardation is sometimes described in patients with hypoparathyroidism, but its etiology remains unknown. 

Histological characteristics of calciphylaxis include small-vessel calcifications of the skin, subcutaneous tissue and visceral organs. These vascular changes promote tissue ischemia that often results in tissue necrosis. 

Placebo-controlled studies In a doubleblind, randomized, placebo-controlled study (40 cases, 40 controls), mesotherapy with disodium edetate (subcutaneous injections of a 15% solution + procaine 1%) in combination with pulse-mode 1 MHz phonotherapy phonophoresis was highly effective in calcific tendinitis of the shoulder there were no injection-site reactions or other adverse events [52 ]. 

Soft tissue masses of the subcutaneous tissue include a variety of lesions, such as calcifications, tophaceous gout or rheumatoid nodules, sebaceous cysts... 

The mechanisms of calcification and the methods of preventing calcification are active areas of current research [106]. The most common methods of studying calcification involve valve tissue implanted either subcutaneously in 3-week-old weanling rats, or valves implanted as mitral replacements, in young sheep or calves. Results of both types of studies show that bioprosthetic tissue calcifies in a fashion similar to clinical implant, but at a greatly accelerated rate. The subcutaneous implantation mode is a well-accepted, technically convenient, economical, and quantifiable model for investigating mineralization issues. It is also very useful for determining the potential of new antimineralization treatments. 

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