Bas et al. (1), in this issue, have demonstrated that acute hypercalcemic clamp over 2 h in rabbits reduces the subsequent intact (I) parathyroid hormone (PTH) response to hypocalcemia by 50%, while chronic hypercalcemia, secondary to experimental renal failure in the same animal model, fails to reduce the I-PTH response to hypocalcemia. These results raise questions about the acute and chronic...

This study investigated the effects of administration of parathyroid hormone (PTH) at different dosages and schedules on bone regeneration in critical-size bone defects in rat calvariae. After calvarial defects had been prepared in 50 rats, they were divided into five treatment groups: 15 µg/kg PTH daily (PTH-15), 35 µg/kg PTH three times per week (PTH-35), 105 µg/kg once per week (PTH-105-1), ...

The plasma disappearance rate (metabolic clearance rate) of administered intact parathyroid hormone (intact PTH) was analyzed in awake dogs with indwelling hepatic and renal vein catheters. The metabolic clearance rate (MCR) of intact PTH was found to be very rapid, 21.6 +/- 3.1 ml/min per kg in 11 normal dogs. The liver accounted for the greatest fraction of the MCR of intact PTH (61 +/- 4%) b...

Parathyroid hormone (PTH) is the major hormone regulating calcium metabolism and is involved in both catabolic and anabolic actions on bone. Intermittent PTH exposure can stimulate bone formation and bone mass when PTH has been injected. In contrast, continuous infusion of PTH stimulates bone resorption. PTH concentration may be affected by physical exercise and our review was designed to inves...

Oxidation of PTH at methionine residues results in loss of biological activity. PTH may be oxidized in patients with renal disease. The aim of this study was to develop an assay considering oxidation of PTH. Oxidized hPTH was analyzed by high resolution nano-liquid chromatography coupled to ESI-FTT tandem mass spectrometry (nanoLC-ESI-FT-MS/MS) directly and after proteolytic cleavage. The oxidi...

BACKGROUND Immunoassays specific for 1-84 parathyroid hormone (PTH) reportedly reflect the bioactivity of PTH; however, PTH immunoassays can be susceptible to interference by cross-reacting PTH fragments. In addition, these assays currently lack standardization. A methodology using immunocapture purification with liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection, along with a ...

BACKGROUND Although the capacity of exogenous PTH1-34 to enhance the rate of bone repair is well established in animal models, our understanding of the mechanism(s) whereby PTH induces an anabolic response during skeletal repair remains limited. Furthermore it is unknown whether endogenous PTH is required for fracture healing and how the absence of endogenous PTH would influence the fracture-he...

A thermoelectric material can convert temperature difference into electrical potential difference. Today, intensive researches are being carried out in order to use flexible, non-toxic and inexpensive conductive polymers instead of hard, hard-to-shape, expensive toxic semiconductor metals used as materials. Among the investigated for this purpose, poly(3,4-ethylenedioxythiophene) (PEDOT) is mos...

Parathyroid hormone (PTH) is a key regulator of bone turnover but can be oxidized in vivo, which impairs biological activity. Variable PTH oxidation may account for the rather poor correlation with indices chronic kidney disease. Here, we tested whether non-oxidized superior to total as marker 31 patients failure included from an ongoing prospective observational biopsy study and selected cover...

PTH stimulates transcellular Ca2+ absorption in renal distal convoluted tubules. The effect of PTH on membrane voltage, the ionic basis of the change in voltage, and the relations between voltage and calcium entry were determined on immortalized mouse distal convoluted tubule cells. PTH (10(-8) M) significantly increased 45Ca2+ uptake from basal levels of 2.81 +/- 0.16 to 3.88 +/- 0.19 nmol min...