Rheumatoid arthritis is associated with a generalised loss of bone mass. One of the factors that have been implicated in the pathogenesis of this bone loss is the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs). These drugs are known to increase gastrointestinal permeability and may thus influence the absorption of calcium; they may also influence glomerular filtration rate and th...

The calcium-sensing receptor (CASR) adjusts the extracellular calcium set point regulating PTH secretion and renal calcium excretion. The receptor is expressed in several tissues and is also involved in other cellular functions such as proliferation, differentiation and other hormonal secretion. High extracellular calcium levels activate the receptor resulting in modulation of several signaling...

Tricalcium phosphate (TCP) synthetized by high temperature solid state reaction at 1400°C and three derived calcium cements (CPCs) prepared liquid to powder (L/P) ratios of 0.33, 0.44 0.55 ml/g, respectively, were physicochemically characterized. Calcium deficient hydroxyapatite crystals identified scanning electron microscopy on CPC, differences in crystal sizes observed different L/P ratios. ...

BtuB is a beta-barrel membrane protein that facilitates transport of cobalamin (vitamin B12) from the extracellular medium across the outer membrane of Escherichia coli. It is thought that binding of B12 to BtuB alters the conformation of its periplasm-exposed N-terminal residues (the TonB box), which enables subsequent binding of a TonB protein and leads to eventual uptake of B12 into the cyto...

Isolated ductal cells of rat submandibular gland phospholipid pools were labeled with [3H]arachidonic acid (AA). The tracer was incorporated preferentially to phosphatidylcholine (46% of the lipidic fraction). Extracellular ATP induced the release of [3H]AA to the extracellular medium in a time- and dose-dependent manner (EC50 = 220 microM). Among other agents tested, only 2', 3'-O-(4-benzoylbe...

The kidney plays a critical role in regulating water homeostasis through specific proteins highly expressed in the kidney, called aquaporins, allowing water permeation at a high rate. This brief review focuses on some nephropathies associated with impaired urinary concentrating ability and in particular analyzes the role of aquaporin 2 in hypercalciuria, the most common metabolic abnormality in...

Mammalian spermatozoa must undergo capacitation and acrosome reaction before fertilization. To date, the precise mechanisms regulating these complex processes are not well understood but it is generally agreed that they involve an influx of calcium from the extracellular space through, as yet, poorly characterized plasma membrane pathways. Here we present evidence for a novel mechanism to incre...

The objective of this study was to elucidate the mechanisms associated with the reciprocal relation between magnesium and calcium on vascular smooth muscle tone in bovine pulmonary artery and vein. Rapid removal of magnesium from Krebs-bicarbonate medium used to bathe isolated rings of precontracted artery or vein caused transient endothelium- and calcium-dependent relaxation and cyclic GMP acc...

The identification and cloning of the extracellular calcium sensing receptor (CaR) has provided a new conceptual framework in which we can better understand the interactions between extracellular calcium and the many cell types which express the CaR. The role of the CaR in regulating extracellular calcium ion homeostasis has been well established, as has its role in genetically determined disor...

In human ageing, changes in calcium distribution take place. The calcium content in bone tissue diminishes and extraskeletal calcifications, especially vascular calcifications, occur. Recent research has documented the fact that the vascular calcification process is regulated [1,2] and that this process is accelerated in uraemia [3]. Multiple factors have been proposed to influence the process ...