Calcium overview

The largest-volume phosphoms compounds are the phosphoric acids and phosphates (qv), ie, the oxide derivatives of phosphoms ia the + 5 oxidation state. With the exception of the phosphoric acid anhydride, P O q, and the phosphate esters, these materials are discussed elsewhere (see Phosphoric acids and phosphates). An overview of phosphoms compounds other than the phosphoric acids and phosphates is given herein. These compounds constitute a large variety of phosphoms compounds that are either nonoxide derivatives or derivatives of phosphoms ia oxidation states lower than + 5. These phosphoms compounds are manufactured only from elemental phosphoms (qv) obtained by reduction of naturally occurring phosphate rock (calcium phosphate). 

Although blood pressure control follows Ohm s law and seems to be simple, it underlies a complex circuit of interrelated systems. Hence, numerous physiologic systems that have pleiotropic effects and interact in complex fashion have been found to modulate blood pressure. Because of their number and complexity it is beyond the scope of the current account to cover all mechanisms and feedback circuits involved in blood pressure control. Rather, an overview of the clinically most relevant ones is presented. These systems include the heart, the blood vessels, the extracellular volume, the kidneys, the nervous system, a variety of humoral factors, and molecular events at the cellular level. They are intertwined to maintain adequate tissue perfusion and nutrition. Normal blood pressure control can be related to cardiac output and the total peripheral resistance. The stroke volume and the heart rate determine cardiac output. Each cycle of cardiac contraction propels a bolus of about 70 ml blood into the systemic arterial system. As one example of the interaction of these multiple systems, the stroke volume is dependent in part on intravascular volume regulated by the kidneys as well as on myocardial contractility. The latter is, in turn, a complex function involving sympathetic and parasympathetic control of heart rate intrinsic activity of the cardiac conduction system complex membrane transport and cellular events requiring influx of calcium, which lead to myocardial fibre shortening and relaxation and affects the humoral substances (e.g., catecholamines) in stimulation heart rate and myocardial fibre tension. 

Overview of Calcium Carbonate Crystallization by Synthetic Substrates... 

In this chapter, we provide a brief overview of voltage-gated calcium channel subtypes and function, with an emphasis on neuronal transmission. The structure and kinetics of calcium channels is an extensive field of study, and outstanding reviews have recently appeared [3,4]. This chapter is focused on the potential opportunities for small-molecule intervention in neuronal signaling via antagonism of voltage-gated calcium channel subtypes, with a brief review of the chemotypes that have been recently reported to modify channel function. 

Fig. 2. Overview of stability constants (logio-Ka, on the molar scale) for formation of calcium complexes in aqueous solution, at (or close to) 298 K and in ionic strengths in the region of 0.1-0.15 M.

Table 13.13 Overview of the adjuvant preparations that have been developed to date, or are under investigation. Of these, aluminium-based substances are the only adjuvants used to any significant degree in humans. Calcium phosphate and oil emulsions find very limited application in human medicine...

Rafferty, K., Walters, G., and Fieaney, R. P. (2007). Calcium fortificants Overview and strategies for improving calcium nutriture of the U.S. population. /. Food Sci. 72, R152-R158. 

Msaouel, P., Nixon, A. M., Bramos, A. P., Baiba, E. and Kentarchos, N. E., 2004, Extracellular calcium sensing receptor an overview of physiology, pathophysiology and clinical perspectives. In Vivo 18, 739-53. 

Vitamin D, along with parathyroid hormone and calcitonin, plays a primary role in calcium and phosphorus homeostasis in the body. Intensive research efforts over the past several years have elucidated a role for vitamin D in many other physiological processes as well. The biological actions of this seco-steroid are mediated primarily through the action of its polar metabolite, 1,25-dihydroxy vitamin D3 (l,25(OH)2D3). There is emerging evidence that l,25(OH)2D3 has many more target tissues than those involved in its classical role in the control of mineral metabolism. In addition, some of the actions of l,25(OH)2D3 may be mediated by mechanisms other than the classical steroid-receptor interaction. In this chapter we will provide a brief overview of the multiple actions of vitamin D3 and the pleiotropic mechanisms by which these actions are accomplished. 

This section presents a brief overview of a few other compounds that have not been described in previous sections. Because it can function as a nonmetal, silicon forms sihcides with several metals. These materials are often considered as alloys in which the metal and silicon atoms surround each other in a pattern that may lead to unusual stoichiometry. Examples of this type are Mo3Si and TiSi2. In some sihcides, the Si-Si distance is about 235 pm, a distance that is quite close to the value of 234 pm found in the diamond-type structure of elemental silicon. This indicates that the structure contains Si22-, and CaSi2 is a compound of this type. This compound is analogous to calcium carbide, CaC2 (actually an acetylide that contains C22- ions (see Chapter 10)). 

An overview is presented on current stabilisers for cables, foamed sheets and profdes, PVC pipes and fittings and profiles, which shows that lead is the most used stabiliser but, like tin, is under pressure in some European countries. Stabiliser systems based on calcium and zinc are considered to be the stabiliser systems of the future. 

Figure 6.1. Overview of cellular calcium transport. Calcium enters the cell through voltage- or ligand-gated channels (left). It is extmded by ATP-driven pumps or by sodium antiport (right). Both the mitochondria and the endoplasmic reticulum serve as intracellular calcium stores. The cytosolic concentration is kept at -100 nM under resting conditions. CaM Calmodulin.

Chemically induced cardiac failure has been the subject of a number of works. Balazs and Ferrans (1978), Baskin (1991), and Acosta (2001) give an overview of the subject. Hypoxia is one of the effects of the decreased availability of ATP which depresses contraction in the muscle. The energy that is supplied by the phosphate bonds is possible only as long as aerobic glycolysis and oxidative phosphorylation are maintained. Under anoxic conditions, this is no longer possible and with the adrenergic stimulus continuing, calcium accumulation in the mitochondria leads to... 

Figure 1 Overview of the synaptic vesicle cycle, (a) Within the presynaptic terminal, synaptic vesicles are filled with neurotransmitter by the action of specific vesicular neurotransmitter transporters, (b) Neurotransmitter-filled vesicles translocate to the active-zone membrane where they undergo docking, (c) Docked vesicles transition to a release-competent state through a series of priming or prefusion reactions, (d) Invasion of an action potential into the presynaptic terminal and subsequent calcium influx induces rapid fusion of the synaptic vesicle membrane with the terminal membrane, which thereby releases the neurotransmitter into the synaptic cleft, (e) Spent vesicles are internalized by clathrin-mediated endocytosis and are recycled for reuse, which thus completes the synaptic vesicle cycle. SV, synaptic vesicle CCV, clathrin-coated vesicle EE, early endosome. NOTE The use of arrows indicates a temporal sequence of events. Physical translocation of synaptic vesicles is unlikely to occur between the docking and fusion steps.

Blood Pressure Lowering Treatment Trialists Collaboration 2000. Effects of ACE inhibitors, calcium antagonists, and other blood-pressurelowering drugs results of prospectively designed overviews of randomised trials. Lancet 355 1955-1964... 

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