Selective activation of diaphyseal chondrocytes by parathyroid hormone, calcitonin and N6,O2-dibutyryl adenosine 3',5'-cyclic monophosphoric acid in proteoglycan synthesis of chick embryonic femur cultivated in vitro.

In this work, for the first time, chlorogenic acid, a natural phytochemical, was conjugated to a lactoferrin derived antimicrobial peptide sequence RRWQWRMKKLG to develop a self-assembled template. To mimic the components of extracellular matrix, we then incorporated Type I Collagen, followed by a sequence of aggrecan peptide (ATEGQVRVNSIYQDKVSL) onto the self-assembled templates for potential applications in ligament tissue regeneration. Mechanical properties and surface roughness were studied and the scaffolds displayed a Young’s Modulus of 169 MP and an average roughness of 72 nm respectively. Thermal phase changes were studied by DSC analysis. Results showed short endothermic peaks due to water loss and an exothermic peak due to crystallization of the scaffold caused by rearrangement of the components. Biodegradability studies indicated a percent weight loss of 27.5 % over a period of 37 days. Furthermore, the scaffolds were found to adhere to fibroblasts, the main cellular component of ligament tissue. The scaffolds promoted cell proliferation and displayed actin stress fibers indicative of cell motility and attachment. Collagen and proteoglycan synthesis were also promoted, demonstrating increased expression and deposition of collagen and proteoglycans. Additionally, the scaffolds exhibited antimicrobial activity against Staphylococcus epidermis bacteria, which is beneficial for minimizing biofilm formation if potentially used as implants. Thus, we have developed a novel biocomposite that may open new avenues to enhance ligament tissue regeneration.

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Calcium-activated proteases in the bovine parathyroid gland: potential role in degradation of parathyroid hormone to peptide fragments

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0150061 ◽

1995 ◽

Vol 15 (1) ◽

pp. 61-71 ◽

Cited By ~ 5

Author(s):

P H Watson ◽

S T Mortimer ◽

K K W Wang ◽

D E Croall ◽

D A Hanley

Keyword(s):

Parathyroid Hormone ◽

Parathyroid Tissue ◽

Area Under The Curve ◽

Molar Ratio ◽

Cell Protein ◽

Parathyroid Cell ◽

Peptide Fragments ◽

Intracellular Degradation ◽

Peak Areas

ABSTRACT Our studies suggest that protein kinase C is involved in low calcium (Ca2+)-stimulated secretion of parathyroid hormone (PTH) but not directly in high Ca2+-stimulated intracellular degradation of PTH to secreted carboxyl-terminal fragments (C-PTH), an important component of Ca2+-regulated PTH secretion. The present study was undertaken to determine the presence of calciumactivated proteases, 84 kDa (micro)-calpain and 80 kDa (milli)-calpain, in the bovine parathyroid, and whether they could degrade PTH to C-terminal fragments. Immunocytochemistry of bovine parathyroid tissue using antibodies raised against bovine heart micro- and milli-calpain detected both isoforms of calpain. Western blotting of total bovine parathyroid cell protein prepared from primary cell cultures confirmed the presence of both isoforms of calpain, demonstrated by specific milli- and micro-calpain bands. Purified bovine PTH (bPTH) was incubated in vitro with human erythrocyte micro-calpain and the cleavage products were separated by reverse-phase HPLC. Eluant fractions were assayed with an RIA with equimolar sensitivity to C-PTH and bPTH, and peak areas integrated. Micro-calpain produced a C-PTH peak from bPTH which co-eluted with the major C-PTH secreted by parathyroid cells in culture. C-PTH production by micro-calpain, expressed as per cent area under the curve, increased from 0% in the absence of either micro-calpain or Ca2+, to 71·5% when a 5:1 molar ratio of bPTH to calpain was used. Amino acid sequencing and analysis of the immunoreactive PTH cleavage products indicated the presence of two fragments of bPTH in the C-PTH peak, bPTH47–84 and bPTH69–84. In summary, both isoforms of calpain are present in the bovine parathyroid and calpains may play a role in the Ca2+-dependent degradation of PTH to secreted C-terminal fragments.

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In vitro model of parathyroid hormone-related protein secretion from mammary cells isolated from lactating cows

Domestic Animal Endocrinology ◽

10.1016/0739-7240(96)00070-7 ◽

1996 ◽

Vol 13 (5) ◽

pp. 399-410 ◽

Cited By ~ 7

Author(s):

H. Okada ◽

F.L. Schanbacher ◽

L.K. McCauley ◽

M.T. Weckmann ◽

C.C. Capen ◽

...

Keyword(s):

Parathyroid Hormone ◽

Protein Secretion ◽

In Vitro Model ◽

Mammary Cells ◽

Related Protein ◽

Lactating Cows ◽

Parathyroid Hormone Related Protein ◽

Vitro Model

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Effect of a protease inhibitor on in vitro stability of intact parathyroid hormone

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1258/000456303763046166 ◽

2003 ◽

Vol 40 (2) ◽

pp. 188-190 ◽

Cited By ~ 6

Author(s):

N. R. Anderson ◽

J. Nicholas ◽

M. R. Holland ◽

R. Gama

Keyword(s):

Parathyroid Hormone ◽

Protease Inhibitor ◽

Protease Activity ◽

Intact Parathyroid Hormone ◽

In Vitro Degradation ◽

Glass Tubes ◽

Edta Plasma ◽

In Vitro Stability ◽

Baseline Sample

Background: We investigated whether increased protease activity explains the increased in vitro degradation of intact parathyroid hormone (iPTH) observed in serum when compared to EDTA plasma. Methods: Pre-dialysis blood samples for iPTH were taken from 11 patients with chronic renal failure and collected into plain glass tubes, tubes containing 200 KIU/mL aprotinin (a protease inhibitor) and EDTA tubes. All sample aliquots were separated at 20 min, 1 h, 2 h, 4 h, 8 h and 24 h post collection. Results: Over 24 h, iPTH concentrations remained unchanged in EDTA tubes. iPTH concentrations were significantly lower in both plain tubes ( P < 0·01) and aprotinin tubes ( P < 0·001) at 24 h when compared to the baseline sample (20 min). At 24 h, iPTH concentrations in EDTA tubes were higher than in plain tubes ( P < 0·001) and aprotinin tubes ( P < 0·01). The addition of aprotinin to plain tubes significantly reduced the degradation of iPTH ( P < 0·05) at 24 h. Conclusion: Aprotinin significantly reduces the in vitro degradation of iPTH in plain tubes at 24 h from 24·7% to 9·6%. We suggest that increased protease activity contributes to the decline in serum iPTH over time. As this is observed in serum and not plasma it suggests that the increased protease activity may be due to the clotting process.

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Direct effect of parathyroid hormone on insulin secretion from pancreatic islets

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.258.6.e975 ◽

1990 ◽

Vol 258 (6) ◽

pp. E975-E984 ◽

Cited By ~ 5

Author(s):

G. Z. Fadda ◽

M. Akmal ◽

L. G. Lipson ◽

S. G. Massry

Keyword(s):

Insulin Secretion ◽

Parathyroid Hormone ◽

Pancreatic Islets ◽

Insulin Release ◽

Direct Effect ◽

Indirect Evidence ◽

Cytosolic Calcium ◽

Dependent Manner ◽

Stimulation Of

Indirect evidence indicates that parathyroid hormone (PTH) interacts with pancreatic islets and modulates their insulin secretion. This property of PTH has been implicated in the genesis of impaired insulin release in chronic renal failure. We examined the direct effect of PTH-(1-84) and PTH-(1-34) on insulin release using in vitro static incubation and dynamic perifusion of pancreatic islets from normal rats. Both moieties of the hormone stimulated in a dose-dependent manner glucose-induced insulin release but higher doses inhibited glucose-induced insulin release. This action of PTH was modulated by the calcium concentration in the media. The stimulatory effect of PTH was abolished by its inactivation and blocked by its antagonist [Tyr-34]bPTH-(7-34)NH2. PTH also augmented phorbol ester (TPA)-induced insulin release, stimulated adenosine 3',5'-cyclic monophosphate (cAMP) generation by pancreatic islets, and significantly increased (+50 +/- 2.7%, P less than 0.01) their cytosolic calcium. Verapamil inhibited the stimulatory effect of PTH on insulin release. The data show that 1) pancreatic islets are a PTH target and may have PTH receptors, 2) stimulation of glucose-induced insulin release by PTH is mediated by a rise in cytosolic calcium, 3) stimulation of cAMP production by PTH and a potential indirect activation of protein kinase C by PTH may also contribute to the stimulatory effect on glucose-induced insulin release, and 4) this action of PTH requires calcium in incubation or perifusion media.

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