The hypoxia inducible factors （Hifs） are evolutionarily conserved transcriptional factors that control homeostatic responses to low oxygen. In developing bone, Hif-1 generated signals induce angiogenesis necessary f...The hypoxia inducible factors （Hifs） are evolutionarily conserved transcriptional factors that control homeostatic responses to low oxygen. In developing bone, Hif-1 generated signals induce angiogenesis necessary for osteoblast specification, but in mature bone, loss of Hif-1 in osteoblasts resulted in a more rapid accumulation of bone. These findings suggested that Hif-1 exerts distinct developmental functions and acts as a negative regulator of bone formation. To investigate the function of Hif-1a in osteoanabolic signaling, we assessed the effect of Hif-1a loss-of-function on bone formation in response to intermittent parathyroid hormone （PTH）. Mice lacking Hif-1a in osteoblasts and osteocytes form more bone in response to PTH, likely through a larger increase in osteoblast activity and increased sensitivity to the hormone. Consistent with this effect, exposure of primary mouse osteoblasts to PTH resulted in the rapid induction of Hif-1a protein levels via a post-transcriptional mechanism. The enhanced anabolic response appears to result from the removal of Hif-1a-mediated suppression of β-catenin transcriptional activity. Together, these data indicate that Hif-1a functions in the mature skeleton to restrict osteoanabolic signaling. The availability of pharmacological agents that reduce Hif-1a function suggests the value in further exploration of this pathway to optimize the therapeutic benefits of PTH.展开更多
Objective The aim of the study was to investigate the effect of parathyroid hormone(PTH) on the apoptosis of human medullary thyroid carcinoma(MTC) cells.Methods In vitro cultured medullary thyroid carcinoma cell line...Objective The aim of the study was to investigate the effect of parathyroid hormone(PTH) on the apoptosis of human medullary thyroid carcinoma(MTC) cells.Methods In vitro cultured medullary thyroid carcinoma cell lines were treated with parathyroid hormone and parathyroid hormone receptor-monoclonal antibody,and the apoptosis of cells was detected by flow cytometry.Results The cell morphology changed significantly after treatment based on the observation using the inverted phase-contrast microscope.Various concentrations of parathyroid hormone and parathyroid hormone receptor-monoclonal antibody effectively induced apoptosis in a time-and concentrationdependent manner.When the concentration of parathyroid hormone was 2.0 μmol/L and that of parathyroid hormone receptor-monoclonal antibody was 1.0 μmol/L,the apoptotic rate was 13.24% and 20.78%,respectively,representing a statistically significant difference from that of the control cells(P < 0.05).Conclusion PTH plays a role in inducing apoptosis of human MTC cells.展开更多
Parathyroid hormone （PTH） secretion is characterized by an ultradian rhythm with tonic and pulsatile components. In healthy subjects, the majority of PTH is secreted in tonic fashion, whereas approximately 30% is se...Parathyroid hormone （PTH） secretion is characterized by an ultradian rhythm with tonic and pulsatile components. In healthy subjects, the majority of PTH is secreted in tonic fashion, whereas approximately 30% is secreted in low-amplitude and high-frequency bursts occurring every 10-20 min, superimposed on tonic secretion. Changes in the ultradian PTH secretion were shown to occur in patients with primary and secondary osteoporosis, with skeletal effects depending on the reciprocal modifications of pulsatile and tonic components. Indeed, pathophysiology of spontaneous PTH secretion remains an area potentially suitable to be explored, particularly in those conditions such as secondary forms of osteoporosis, in which conventional biochemical and densitometric parameters may not always give reliable diagnostic and therapeutic indications. This review will highlight the literature data supporting the hypothesis that changes of ultradian PTH secretion may be correlated with skeletal fragility in primary and secondary osteoporosis.展开更多
Objective： The purpose of the study was to investigate the effects of parathyroid hormone and parathyroid hormone receptor monoclonal antibody on in vitro growth and proliferation of human medullary thyroid carcinoma...Objective： The purpose of the study was to investigate the effects of parathyroid hormone and parathyroid hormone receptor monoclonal antibody on in vitro growth and proliferation of human medullary thyroid carcinoma cell lines. Methods： The medullary thyroid carcinoma cell line was cultured in vitro, with parathyroid hormone and parathyroid hormone receptor monoclonal antibody treatment intervention, the growth of the cells was observed under an inverted contrast micro scope, the MTT assay was used to detect the cell growth inhibition rate. Results： Under the inverted contrast microscope, the cells changed significantly, the parathyroid hormone and parathyroid hormone receptor monoclonal antibodies can effectively inhibit the proliferation of medullary thyroid cancer cells in a time and dose dependent. When parathyroid hormone concentra tion reached a concentration of 2.0 IJmol/L, the parathyroid hormone receptor monoclonal antibody reached a concentration of 1.0 μmol/L, the cell growth was most significantly inhibited （P 〈 0.05）. Conclusion： Parathyroid hormone and parathyroid hormone receptor monoclonal antibody were able to inhibit the proliferation of medullary thyroid carcinoma cells and signifi cantly reduce the proliferation index.展开更多
Introduction: Following orthognathic surgery, increased tooth mobility is observed clinically and is utilized for postsurgical orthodontic tooth movement. It was suggested that the increase may result from a surgery-a...Introduction: Following orthognathic surgery, increased tooth mobility is observed clinically and is utilized for postsurgical orthodontic tooth movement. It was suggested that the increase may result from a surgery-associated alteration of parathyroid hormone (PTH) and calcium metabolism. Materials and Methods: 30 young adult patients were divided into a mandibular osteotomy group (Group A, n = 20) and an untreated control group (Group B, n = 10). Tooth mobility was evaluated using the Periotest device. Tooth mobility, serum PTH and calcium levels were determined repeatedly for both groups. Results: The tooth mobility was increased significantly in the Group A patients in the first 10 days post-surgery. All serum PTH and calcium mean levels were within normal ranges. No significant differences were found between the measurements of both groups. The serum calcium levels recorded at the 1st post-surgery day were slightly lower in the operated patients compared to the control group. Conclusion: It can be concluded that the increased facility of orthodontic tooth movement immediately post-surgery was confirmed by Periotest measurements, while no association was found with surgery-related altered levels of PTH and calcium. Since dietary effects can be ruled out, the increase of clinical tooth mobility may rather result from preoperative orthodontic forces and/or the post-surgical elimination of masticatory muscular influences.展开更多
基金Support was provided by a Career Development Award (RCR, BX001284) from the Veterans Administration
文摘The hypoxia inducible factors （Hifs） are evolutionarily conserved transcriptional factors that control homeostatic responses to low oxygen. In developing bone, Hif-1 generated signals induce angiogenesis necessary for osteoblast specification, but in mature bone, loss of Hif-1 in osteoblasts resulted in a more rapid accumulation of bone. These findings suggested that Hif-1 exerts distinct developmental functions and acts as a negative regulator of bone formation. To investigate the function of Hif-1a in osteoanabolic signaling, we assessed the effect of Hif-1a loss-of-function on bone formation in response to intermittent parathyroid hormone （PTH）. Mice lacking Hif-1a in osteoblasts and osteocytes form more bone in response to PTH, likely through a larger increase in osteoblast activity and increased sensitivity to the hormone. Consistent with this effect, exposure of primary mouse osteoblasts to PTH resulted in the rapid induction of Hif-1a protein levels via a post-transcriptional mechanism. The enhanced anabolic response appears to result from the removal of Hif-1a-mediated suppression of β-catenin transcriptional activity. Together, these data indicate that Hif-1a functions in the mature skeleton to restrict osteoanabolic signaling. The availability of pharmacological agents that reduce Hif-1a function suggests the value in further exploration of this pathway to optimize the therapeutic benefits of PTH.
基金Supported by a grant from the Science and Technology Plan Projects of Lanzhou(No.2013-3-38)
文摘Objective The aim of the study was to investigate the effect of parathyroid hormone(PTH) on the apoptosis of human medullary thyroid carcinoma(MTC) cells.Methods In vitro cultured medullary thyroid carcinoma cell lines were treated with parathyroid hormone and parathyroid hormone receptor-monoclonal antibody,and the apoptosis of cells was detected by flow cytometry.Results The cell morphology changed significantly after treatment based on the observation using the inverted phase-contrast microscope.Various concentrations of parathyroid hormone and parathyroid hormone receptor-monoclonal antibody effectively induced apoptosis in a time-and concentrationdependent manner.When the concentration of parathyroid hormone was 2.0 μmol/L and that of parathyroid hormone receptor-monoclonal antibody was 1.0 μmol/L,the apoptotic rate was 13.24% and 20.78%,respectively,representing a statistically significant difference from that of the control cells(P < 0.05).Conclusion PTH plays a role in inducing apoptosis of human MTC cells.
文摘Parathyroid hormone （PTH） secretion is characterized by an ultradian rhythm with tonic and pulsatile components. In healthy subjects, the majority of PTH is secreted in tonic fashion, whereas approximately 30% is secreted in low-amplitude and high-frequency bursts occurring every 10-20 min, superimposed on tonic secretion. Changes in the ultradian PTH secretion were shown to occur in patients with primary and secondary osteoporosis, with skeletal effects depending on the reciprocal modifications of pulsatile and tonic components. Indeed, pathophysiology of spontaneous PTH secretion remains an area potentially suitable to be explored, particularly in those conditions such as secondary forms of osteoporosis, in which conventional biochemical and densitometric parameters may not always give reliable diagnostic and therapeutic indications. This review will highlight the literature data supporting the hypothesis that changes of ultradian PTH secretion may be correlated with skeletal fragility in primary and secondary osteoporosis.
基金Supported by a grant from the Science and Technology Plan Projects of Lanzhou(No.2013-3-38)
文摘Objective： The purpose of the study was to investigate the effects of parathyroid hormone and parathyroid hormone receptor monoclonal antibody on in vitro growth and proliferation of human medullary thyroid carcinoma cell lines. Methods： The medullary thyroid carcinoma cell line was cultured in vitro, with parathyroid hormone and parathyroid hormone receptor monoclonal antibody treatment intervention, the growth of the cells was observed under an inverted contrast micro scope, the MTT assay was used to detect the cell growth inhibition rate. Results： Under the inverted contrast microscope, the cells changed significantly, the parathyroid hormone and parathyroid hormone receptor monoclonal antibodies can effectively inhibit the proliferation of medullary thyroid cancer cells in a time and dose dependent. When parathyroid hormone concentra tion reached a concentration of 2.0 IJmol/L, the parathyroid hormone receptor monoclonal antibody reached a concentration of 1.0 μmol/L, the cell growth was most significantly inhibited （P 〈 0.05）. Conclusion： Parathyroid hormone and parathyroid hormone receptor monoclonal antibody were able to inhibit the proliferation of medullary thyroid carcinoma cells and signifi cantly reduce the proliferation index.
文摘Introduction: Following orthognathic surgery, increased tooth mobility is observed clinically and is utilized for postsurgical orthodontic tooth movement. It was suggested that the increase may result from a surgery-associated alteration of parathyroid hormone (PTH) and calcium metabolism. Materials and Methods: 30 young adult patients were divided into a mandibular osteotomy group (Group A, n = 20) and an untreated control group (Group B, n = 10). Tooth mobility was evaluated using the Periotest device. Tooth mobility, serum PTH and calcium levels were determined repeatedly for both groups. Results: The tooth mobility was increased significantly in the Group A patients in the first 10 days post-surgery. All serum PTH and calcium mean levels were within normal ranges. No significant differences were found between the measurements of both groups. The serum calcium levels recorded at the 1st post-surgery day were slightly lower in the operated patients compared to the control group. Conclusion: It can be concluded that the increased facility of orthodontic tooth movement immediately post-surgery was confirmed by Periotest measurements, while no association was found with surgery-related altered levels of PTH and calcium. Since dietary effects can be ruled out, the increase of clinical tooth mobility may rather result from preoperative orthodontic forces and/or the post-surgical elimination of masticatory muscular influences.
