Bone ectopic

Islands of neuroglial tissue occurring outside the central nervous system (CNS) are uncommon but have been described in a variety of sites in the head and neck. Two of the most common sites are the nose ( nasal glioma ) and middle ear-temporal bone. " Ectopic neuroglial tissue (ENGT) should not be confused with an encepha-locele. An encephalocele retains a connection to the CNS, whereas ENGT does not. 

Taking the contraceptive hormones provides health benefits not related to contraception, such as regulating the menstrual cycle and decreased blood loss, and incidence of iron deficiency anemia, and dysmenorrhea Health benefits related to the inhibition of ovulation include a decrease in ovarian cysts and ectopic pregnancies. hi addition, there is a decrease in fibrocyctic breast disease, acute pelvic inflammatory disease endometrial cancer, ovarian cancer, maintenance of bone density, and symptoms related to endometriosis in women taking contraceptive hormones. Newer combination contraceptives such as norgestimate and ethinyl estradiol... 

Lucas, P. A., Laurencin, C., Syftestad, G. T., Domb, A., Goldberg, V. M., Caplan, A. I., and Langer, R., Ectopic induction of cartilage and bone by water-soluble proteins from bovine bone using a polyanhydride delivery vehicle, J. Control. Rel. In Press. 

Bone morphogenetic proteins (BMPs) A family (eight or more) of secreted proteins with a variety of actions on bone many induce ectopic bone growth. 

Lufkin, T., Mark, M., Hart, C. P Dolle, R, LeMeur, M., and Chambon, P. (1992). Homeotic transformation of the occipital bones of the skull by ectopic expression of a homeobox gene. Nature 359 835-841. 

Sakamoto, A., Chen, M., Kobayashi, T., Kronenberg, H. M., and Weinstein, L. S. (2005) Chondrocyte-specific knockout of the G protein G(s)alpha leads to epiphyseal and growth plate abnormalities and ectopic chondrocyte formation. J. Bone Miner. Res. 20, 663-671. 

The hypercalcemia resulting from hypervitaminosis D is responsible for toxic symptoms such as muscle weakness, bone pain, anorexia, ectopic calcification, hypertension, and cardiac arrhythmias. Toxicity in infants can result in mental and physical retardation, renal failure, and death. 

Calcium Multiple physiologic actions through regulation of multiple enzymatic pathways Strontium suppresses bone resorption and increases bone formation, calcium and phosphate required for bone mineralization Osteoporosis, osteomalacia, deficiencies in calcium or phosphate Ectopic calcification... 

Today, with the exception of bone marrow for hematopoietic reconstitution, therapeutic cellular transplantation is an emerging technology. In recent years novel approaches in the potential restoration of function through cellular transplantation have included the use of fetal human or xenogeneic neural tissue for Parkinson s disease, ectopically implanted pancreatic islets for diabetes, Schwann cells and olfactory ensheathing glia for spinal cord injury, encapsulated chromaffin cells for pain, and various types of stem cells for the treatment of diabetes, cardiac disease, and central nervous system injuries or disease [2], There have also been trials of encapsulated cells to provide enzymes that either remove toxic products or provide activation of prodrugs to therapeutics, usually anticancer derivatives. 

One of the most sensitive bioassays for osteoblast and osteoclast activities in vivo is the use of ectopic models of bone formation and bone matrix resorption (38,39). Devitalized, demineralized bone powders (DBP) are subcutaneously implanted in young rats. There is a phenotypic conversion of connective cell tissue mesenchyme into cartilage. Subsequently this cartilage becomes calcified, vascularized and bone is deposited in two weeks. If mineral-containing bone particles (BP) are implanted, a different phenomenon is observed. Large multinucleated osteoclast-like cells are recruited to the site of implantation. There is a complete resorption of the BP four weeks after implantation. In collaboration with Dr. Julie Glowacki of the Harvard University School of Medicine, we took advantage of these procedures and used implants of normal DBP and BP into rats that had been maintained on the three experimental diets C, L, and D (40). 

Alkaline phosphatase catalyzes the biochemical splitting of phosphoric acid ester. AP (W.M. Roberts, 1933) is found in the liver, bone, kidney, intestine, lung and placenta. A Regan isoenzyme can be detected as an ectopic variation of placental AP in tumour patients (10-30% of cases). The AP of the liver is located in the cytoplasm and in the membranes, primarily at the biliary pole. Placental AP is also present in the liver. The AP of bile duct epithelia is not elevated in healthy individuals. The serum activity of AP is predominantly due to the isoenzymes of the liver and osteoblasts only 14% are of renal origin. Half-life is 3-7 days. 

The basic differences between cancer cells and normal edh are uncontrolled cell proliferation, decreased cellular differentiation, ability to invade surrounding tissue, and ability ip establish new growth at ectopic sites (metastasis). Conuaiy to popular belief, not all tumor cells proliferate rapidly. Plv-liferation rates vary widely with the cell type. Thus, lymphomas and normal intestinal mucosa both proliferate fasui than. solid tumors. Acute leukemia cells actually prolifemc more slowly than the corresponding precursors in normal bone marrow. 

Mineralization therefore occurs in bone because of the exclusive co-expression in osteoblasts of type I collagen and tissue-nonspecific alkaline phosphatase (TNAP). The abnormal appearance of TNAP in any cell that also produces fibrillar collagen (ectopic TNAP expression) gives rise to pathological (nonbacterial) mineralization, which is outside the scope of this text. 

Extraskeletal calcification occurs in several conditions unrelated to demonstrable abnormalities of calcium metabolism, such as scleroderma, myositis ossificans, calcinosis universalis, calcinosis cutis, and local tissue damage in the kidney. These disorders are not usually associated with changes in serum alkaline phosphatase (B30). Elevated values have, however, been reported in paraplegic patients with ectopic bone formation (F23), and a positive correlation has been demonstrated between the activity of serum alkaline phosphatase and the progression of this disorder. Nicholas (N4) claimed that hyperphosphatasemia in such a situation may help to differentiate thrombophlebitis, septic arthritis, and cellulitis from ectopic bone formation. 

Furman, R., Nicholas, ]. ]., andjivoff, L., Elevation of the serum alkaline phosphatase coincident with ectopic-bone formation in paraplegic patients. ]. Bone Joint Surg. 52A, 1131-1137 (1970). 

N4. Nicholas, J. J., Ectopic bone formation in patients with spinal cord injury. Arch. Phys. Med. Rehabil. 54, 354-359 (1973). 

Also, these high amounts of BMP, a thousand times the natural concentration, are known to trigger ectopic bone growth in susceptible patients, just as found by Urist, 1965 in his rabbit experiments. 

Vaquete, C., Ivanovski, S., Hamlet, S.M., and Hutmacher, D.W. (2013) Effect of culture conditions and calcium phosphate coating on ectopic bone formation. Biomaterials, 34, 5538-5551. 

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