Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Parathyroid cells were obtained by collagenase digestion of 2 g of human parathyroid tissue obtained at surgery from a patient with end stage renal failure and hypercalcemia. Cells were placed into monolayer culture in supplemented Waymouth's MB752/1. Secretion of parathyroid hormone (PTH) from monolayer cultures was inhibited for 3 weeks by 2.5 mM compared to 0.5 mM calcium. The inhibition was 50% on day 3 of culture, and decreased to 19% by day 21. When cultures were incubated with [3H]leucine, radioactive PTH and COOH-terminal PTH fragments were secreted. Sequence analyses were performed on material in radioactive and immunoreactive peaks following gel filtration and high performance liquid chromatography of media. The results indicated that cleavage of PTH or fragments thereof occurred at the 23-24, 27-28, and 33-34 peptide bonds. NH2-terminal fragments of PTH were not detected in media.
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PMID:Structural analysis of parathormone fragments elaborated by cells cultured from a hyperplastic human parathyroid gland. 350 16

Parathyroid Hormone (PTH) stimulates calcium entry into bone cells in vitro, and this effect has been proposed to mediate the actions of PTH on bone. Using cells harvested from infant rat calvaria by collagenase digestion, we evaluated the sensitivity and specificity of this phenomenon. Calcium uptake was temperature dependent, and was increased by PTH over the concentration range 0.01 to 0.50 units/ml. A series of nonhormonal peptides obtained during the purification of a single batch of PTH was found to stimulate calcium uptake. In addition, isoproterenol, ACTH, calcitonin, and glucagon stimulated calcium uptake. In no case, however, was the degree of stimulation as great as that produced by biologically active PTH. Prostaglandins are also potent resorbers of bone, and a series of prostaglandins also stimulated calcium uptake into bone cells. These results are compatible with a calcium ionophore model of PTH and prostaglandin action on bone.
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PMID:Parathyroid hormone as a calcium ionophore in bone cells: tests of specificity. 677 90

Allotransplantation of microencapsulated parathyroid tissue is a promising approach to the treatment of permanent hypoparathyroidism. Preoperative assessment of the quality of microencapsulated parathyroid tissue could facilitate selection of the optimal bioartifical graft for human parathyroid allotransplantation. Parathyroid tissue from patients with secondary hyperparathyroidism (n = 15) was processed mechanically or enzymatically (collagenase type II). Tissue particles and single cells/cell clusters were routinely microencapsulated with amitogenic Ba(2+) alginate. Parathyroid secretion dynamics in response to stimulation of nonencapsulated and microencapsulated parathyroid tissue with Ca(2+) were evaluated in a perifusion system. The stability of the different types of microcapsule was assessed using an osmotic pressure test. Mechanical cutting of parathyroid tissue led to peripheral necrosis of tissue particles and impaired their vitality. Collagenase digestion, in contrast, resulted in single cells and cell clusters without peripheral necrosis. The quality of microencapsulation of single cells/cell clusters was significantly better than that of tissue particles (deformed and imperfect capsules). Microencapsulation itself did not decrease cell vitality. Nonencapsulated and microencapsulated tissue particles and single cells/cell clusters from different donors maintained their own levels of response to stimulation with low Ca(2+). Microcapsules containing tissue particles showed poor stability compared with those containing single cells/cell clusters. Preoperative evaluation of microencapsulated parathyroid tissue can disclose differences in vitality and function and thus facilitate selection of the optimal bioartifical graft for human parathyroid allotransplantation.
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PMID:Preoperative evaluation of microencapsulated human parathyroid tissue aids selection of the optimal bioartificial graft for human parathyroid allotransplantation. 1751 31