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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of the Ca antagonist, verapamil, on the behaviour of parathyroid hormone was studied in normal and uraemic male Wistar rats. Parathyroidectomy was by cautery. Acute uraemia was induced by bilateral nephrectomy, and moderate uraemia by s.c. injection of gentamicin (200 mg/kg). Ethylendiamine tetracetic acid (50 mg/kg X d) was injected subcutaneously. Parathyroid hormone was determined by radioimmunoassay. The degree of uraemia was determined from plasma urea levels. Renal failure resulted in a significant increase in plasma parathyroid hormone (mean +/- SEM, ng/l) (84 +/- 6, n = 10, in the control; 277 +/- 39, n = 7, in the moderate uraemics and 667 +/- 128, n = 6, in the acute uraemics). Injection of verapamil significantly increased plasma levels of parathyroid hormone, ranging from 21% in the controls to 62% in the moderate uraemia group. In the acute uraemics, parathyroid hormone levels were very high and verapamil did not cause any further elevation of the hormone in the blood. Parathyroidectomy significantly lowered plasma parathyroid hormone, and verapamil resulted in a mean increase of 29%. EDTA caused an increase of 64%, compared with the control group.
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PMID:Effect of verapamil on plasma parathyroid hormone. 357 10

Plasma concentrations of parathyroid hormone-related protein (PTHrP), parathyroid hormone, alkaline phosphatase, osteocalcin and albumin-adjusted calcium were measured along with nephrogenous cyclic adenosine monophosphate (NcAMP) in 10 normal women longitudinally through pregnancy. In addition, an assessment of bone resorption was made in these same subjects by the measurement in true fasting urine specimens of the calcium/creatinine ratio (Ca/Cr), hydroxyproline/creatinine ratio (HP/Cr), pyridinoline/creatinine ratio (Pyr/Cr) and deoxypyridinoline/creatine ratio (Dpyr/Cr). The PTHrP level rose through pregnancy from (mean +/- SEM) 0.8 +/- 0.2 pmol/l in the first trimester to 2.7 +/- 0.2 pmol/l 6 weeks postpartum (p < 0.0001). Serum alkaline phosphatase rose from 94 +/- 8 U/l (first trimester) to 347 +/- 25 U/l at term (p < 0.0001). A significant positive correlation was evident between PTHrP and alkaline phosphatase up to term (r = 0.44, p < 0.005). Parathyroid hormone concentrations remained unchanged during pregnancy but rose significantly postpartum from 1.8 +/- 0.2 pmol/l (first trimester) to 3.1 +/- 0.5 pmol/l (p < 0.0001). Similarly, osteocalcin, a marker of bone formative activity, remained unchanged through pregnancy but rose significantly at 6 weeks after delivery to 0.38 +/- 0.05 nmol/l from 0.19 +/- 0.03 nmol/l (first trimester) (p = 0.019). No significant change was noted in serum-adjusted calcium or NcAMP, either through pregnancy or at the postpartum assessment. Fasting urinary Ca/Cr fell through pregnancy from 0.70 +/- 0.11 (first trimester) to a nadir of 0.19 +/- 0.04 6 weeks postpartum (p = 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Changes in calciotrophic hormones and biochemical markers of bone turnover in normal human pregnancy. 792 Dec 25

Cardiac transplantation has become a successful therapy for end-stage heart disease. However, increased bone loss has been observed in heart transplant recipients, sometimes being responsible for osteoporotic fractures. Glucocorticoids cause dose-related bone loss, particularly in the first 6-12 months of use, but cyclosporine might play a role as well. The evolution of bone mineral density (BMD) and biochemical parameters was prospectively assessed in 24 patients (mean age 52 years) from cardiac transplantation. All patients received cyclosporin A (CsA) and prednisone, the latter at decreasing dosage. The mean current daily dose of CsA was 321 mg and serum levels of CsA were constant. All patients received calcium (500 mg day-1) and vitamin D (1000 U day-1) for prevention of bone loss. BMD (gcm-2) was measured in 17 patients at the lumbar spine, femoral neck and total hip with dual energy X-ray absorptiometry every 6 months. Spinal BMD as well as neck and total hip BMD decreased at 6 and 12 months after transplantation, being statistically significant at the three sites: -5.6 and -3.4% for the lumbar spine, -9.3 and -8.5% for the femoral neck, -4.8% and -6.0% for the total hip respectively. Parathyroid hormone (PTH) and osteocalcin (BGP) increased by 90% and 800% respectively between pretransplantation values and 18 months after transplantation. BGP levels measured every 2 months from transplantation increased continuously from 8.7 micrograms L-1 (mean +/- SEM) before transplantation to 31.3 +/- 10.1 (P < 0.05) at 4 months, to 59.1 +/- 8.8 (P < 0.01) at 6 months and to 72.2 +/- 9.9 (P < 0.01) at 18 months (Kruskal-Wallis analysis: P < 0.0001). PTH showed a biphasic pattern with an initial decrease from 39.3 +/- 4.1 ng L-1 at baseline to 22.0 +/- 2.8 ng L-1 at 2 months, but increasing thereafter to 45.9 +/- 5.7 at 6 months and 74.2 +/- 8.9 at 18 months (Kruskal-Wallis analysis: P < 0.001). These variations represent a glucocorticoid-induced osteoporosis. In summary, cardiac transplant patients lose bone immediately after transplantation at the spine and the hip. Later on, the loss in BMD discontinues at all sites of the skeleton, but predominantly at the spine, and a few patients still lose bone at the hip. This is probably a result of the high bone turnover either due to secondary hyperparathyroidism or induced by cyclosporin A.
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PMID:Cyclosporine induces high bone turnover and may contribute to bone loss after heart transplantation. 886 16

Parathyroid hormone (PTH) related peptide (PTHrP) is thought to influence the proliferation and differentiation of the epidermis and hair follicle. As a means of elucidating the biologic function of PTHrP on the hair follicle, a PTHrP analog PTH (7-34), which is a PTH/PTHrP receptor antagonist, was given intraperitoneally twice daily to C57 BL/6 mice at different stages of the hair cycle. PTH (7-34) induced 99 +/- 4.5% (mean +/- SEM) of resting telogen hair follicles into a proliferative (anagen) state, whereas 100% of the hair follicles in the control group remained in telogen. To determine whether this peptide influenced the progression of the hair follicles from anagen to catagen (hair follicle maturation and regression), groups of mice that were either spontaneously in or induced to anagen received either PTH (7-34) or placebo. Morphometric analysis of the hair follicles from the middle back region of the spontaneous anagen mice that received PTH (7-34) revealed that 19 +/- 4% (mean +/- SEM) of the follicles were in anagen VI, whereas none (0%) were in anagen in the control group. Similarly, in induced anagen mice treated with PTH (7-34), 22.3 +/- 1.4 (mean +/- SEM) of the follicles were in anagen VI compared to only 1.3 +/- 0.7% in the control mice. Together these observations suggest that PTHrP is a hair follicle morphogen that may be a major factor responsible for controlling the hair cycle. These studies provide a new insight for development of PTHrP analogs for a wide variety of disorders related to disturbances of hair cycling.
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PMID:Control of hair growth with parathyroid hormone (7-34). 918 24

To study mineral metabolism in geriatric dogs, parathyroid hormone, calcitriol, ionised calcium, phosphorus, blood urea nitrogen and creatinine were evaluated in 35 geriatric dogs (> 10 years) and in 20 young adult dogs (2-5 years). Parathyroid hormone levels were within the normal range in both groups, but values (mean +/- SEM) were greater in the old dogs (34.8 +/- 3.6 vs 21.2 +/- 2.3 pg ml(-1), P=0.005). Calcitriol and ionised calcium were similar in the two groups, and the values for both parameters were within the normal reference range. Plasma phosphorus levels were in the normal range in both groups but tended to be greater in the older dogs (P=0.09). While blood urea nitrogen was similar in the two groups, creatinine levels (mean +/- SEM) were higher in the young dogs (82.2 +/- 3.5 vs 101.7 +/- 4.4 micromol litre(-1)). Even when the dogs were matched for weight, plasma creatinine concentration was still greater in the younger dogs. In conclusion, an increase in parathyroid hormone without changes in calcium, phosphorus and calcitriol has been identified in geriatric dogs.
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PMID:Mineral metabolism in healthy geriatric dogs. 969 Jun 1

Tumour-induced hypercalcaemia (TIH) is a frequent complication of advanced cancer but has been rarely reported in patients with malignant melanoma, and its pathogenesis remains unexplored. We studied eight patients with TIH and melanoma. We determined the incidence and pathogenesis of this complication and the effects of bisphosphonate therapy. The incidence of TIH in 751 patients with melanoma was 1.1%. All patients had liver and bone metastases at the time of hypercalcaemia. All patients had osteolytic lesions, most often multiple. The median survival was 30 days (range 4-136 days). After rehydration, the mean (+/- SEM) corrected calcium was 3.42 +/- 0.17 mmol/l. Parathyroid hormone levels were adequately suppressed and vitamin D concentrations were normal. Serum osteocalcin, a marker of bone formation, was low, except in the two patients with renal insufficiency, whereas fasting urinary calcium and hydroxyproline were increased, indicating inhibition of bone formation and stimulation of bone resorption. Increased parathyroid hormone-related protein secretion was noted in only one patient. Three of four patients became normocalcaemic after bisphosphonate therapy for a median duration of 2 weeks. In conclusion, hypercalcaemia is a rare complication of melanoma. It occurs in the context of far advanced disease and is essentially due to aggressive lytic bone metastases with an uncoupling in bone turnover. Bisphosphonates can offer short-term palliation.
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PMID:Hypercalcaemia of melanoma: incidence, pathogenesis and therapy with bisphosphonates. 1159 84

Human Parathyroid hormone 1-34 (PTH1-34) loaded chitosan nanoparticles (PTH 1-34 chitosan nanoparticles) via simple ionic gelation technique were prepared which can improve the bioavailability and half-life of the peptide. Chitosan nanoparticles and PTH 1-34 chitosan nanoparticles were synthesised and characterized by DLS, SEM, AFM, FT-IR and TG/DTA. Chitosan nanoparticles (40-60 nm) and PTH 1-34 chitosan nanoparticles (60-80 nm) with zeta potential of +60 and +40 mV respectively were subjected to haemolysis assay and tested for agglomeration in blood. MTT and LDH was performed assay using Saos-2, UMR 106, L929, NIH3T3. The in vitro peptide release profile at pH 7.5 for 144 h was quantified using PTH 1-34 ELISA Kit. Effect of released PTH 1-34 on Saos-2 was determined with ALP and BCA assay. These preliminary results pave way for the prospective use of such a carrier for the delivery of PTH 1-34 by multiple routes for the benefit of patients undergoing treatment for osteoporosis.
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PMID:Synthesis, characterization and preliminary in vitro evaluation of PTH 1-34 loaded chitosan nanoparticles for osteoporosis. 2251 98

The goals of the present study are to establish an in vitro co-culture model of osteoblast and osteoclast function and to quantify the resulting bone remodeling. The bone is tissue engineered using well-defined silk protein biomaterials in 2D and 3D formats in combination with human cells expressing tethered agonists for selected G protein-coupled receptors (GPCRs). The tethered constructs are introduced with the objective of triggering sustained and localized GPCR signaling. The cell-modified biomaterial surfaces are reconstructed from SEM images into 3D models using image processing for quantitative measurement of surface characteristics. Parathyroid hormone (PTH) and glucose-dependent insulinotropic peptide (GIP) are selected because of their roles in bone remodeling for expression in tethered format on bone marrow derived human mesenchymal stem cells (hMSCs). Increased calcium deposition and increased surface roughness are found in 3D digital surface models constructed from SEM images of silk protein films remodeled by the co-cultures containing the tethered PTH, and decreased surface roughness is found for the films remodeled by the tethered GIP co-cultures. Increased surface roughness is not found in monocultures of hMSCs expressing tethered PTH, suggesting that osteoclast-osteoblast interactions in the presence of PTH signaling are responsible for the increased mineralization. These data point towards the design of in vitro bone models in which osteoblast-osteoclast interactions are mimicked for a better understanding of bone remodeling.
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PMID:Cell-tethered ligands modulate bone remodeling by osteoblasts and osteoclasts. 2541 10