Magnesium, deficiency

Magnesium sulfate may be effective in terminating refractory ventricular tachyarrhythmias, particularly polymorphic ventricular tachycardia. DigitaUs-induced arrhythmias are more likely in the presence of magnesium deficiency. Magnesium sulfate can be administered orally, intramuscularly, or, preferably, intravenously,... 

Distinguish symptoms of excess and deficient magnesium levels. /Tn Identify diagnostic values associated with magnesium imbalances. 

Magnesium is closely associated with calciiun and phosphorus. About 70 per cent of the total magnesium is found in the skeleton but the remainder, which is distributed in the soft tissues and fluids, is of crucial importance to the well-being of the animal. Magnesium is the commonest enzyme activator, for example in systems with thiamin pyrophosphate as a cofactor, and oxidative phosphorylation is reduced in magnesium deficiency. Magnesium is an essential activator of phosphate transferases (e.g. creatine kinase) and it activates pyruvate carboxylase, pyruvate oxidase and reactions of the tricarboxylic acid cycle therefore, it is essential for the... 

The hydrides of beryllium and magnesium are both largely covalent, magnesium hydride having a rutile (p. 36) structure, while beryllium hydride forms an electron-deficient chain structure. The bonding in these metal hydrides is not simple and requires an explanation which goes beyond the scope of this book. 

Magnesium is essential to most plant and animal life (see Mineral NUTRIENTS). Dietary deficiency, rather than toxicity, is the more significant problem. 

Other Calcium Disorders. In addition to hypocalcemia, tremors, osteoporosis, and muscle spasms (tetary), calcium deficiency can lead to rickets, osteomalacia, and possibly heart disease. These, as well as Paget s disease, can also result from faulty utilization of calcium. Calcium excess can lead to excess secretion of calcitonin, possible calcification of soft tissues, and kidney stones when combined with magnesium deficiency. 

Magnesium ion is essential for normal Ca " and K" metaboHsm. In acute experimental magnesium deficiency in humans, hypocalcemia occurs despite adequate calcium intake and absorption and despite normal renal and parathyroid functions. Negative K" balance is also observed. AH biochemical and clinical abnormaHties disappear upon restoration of adequate amounts of magnesium to the diet (64). 

OtherMa.gnesium Disorders. Neuromuscular irritabHity, convulsions, muscle tremors, mental changes such as confusion, disorientation, and haHucinations, heart disease, and kidney stones have aH been attributed to magnesium deficiency. Excess Mg " can lead to intoxication exemplified by drowsiness, stupor, and eventuaHy coma. 

Magnesium deficiency has been long recognized, but hypermagnesia also occurs (Anderson and Talcott 1994). Magnesium can be determined in fluids by FAAS, inductively coupled plasma atomic emission spectrometry (ICP-AES) and ICP-MS. In tissue Mg can be determined directly by solid sampling atomic absorption spectrometry (SS-AAS) (Herber 1994a). Both Ca and Mg in plasma/serum are routinely determined by photometry in automated analyzers. 

Cakmak, C. Hengeler, and H. Manschner, Changes in phloem export of sucrose in leaves in response to phosphorus, potassium and magnesium deficiency in beau plants. J. Exp. Bot. 45 1251 (1994). 

Nutrient deficiencies may also influence the production of allelochemics. The compounds studied in great detail have been the phenolic compounds and scopolin-related chemicals. Deficiencies of boron, calcium, magnesium, nitrogen, phosphorus, potassium, and sulfur have all been reported to enhance the concentration of chlorogenic acids and scopolin in a variety of plants (4). In other species, chlorogenic acids have decreased in plants that are deficient in magnesium or potassium. 

Variation in the magnesium (Mg) content of the medium may exert a marked effect on cell division of some bacteria. In a Mg-deficient medium, Gram-positive rods grow in the form of long filaments. Such filaments revert to normal forms when transferred to the same medium supplemented with suitable concentrations of Mg. Filament formation is enhanced by the addition of zinc and cobalt. Inhibition of cell division occurs also in media supplemented with an excess of Mg. 

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