Calcium during development

Figure 2. Calcium-nitrogen ratio of the nonepiphyseal parts of the human femur during development. (Reproduced with permission from Ref. 1. Copyright 1965 W. B. Saunders Company.)...

Nigam SK, Rodriguez-Boulan E, and Silver RB [1992] Changes in intracellular calcium during the development of epithelial polarity and junctions. Proc Natl Acad Sci USA 89 6162-6166... 

A variety of other calcium transport systems are associated with Ca21-activated ATPases. The extraembryonic structure, the chorioallantoic membrane, of the chick embryo is responsible for the translocation of over 120 mg of eggshell calcium into (he embryo during development. The enzyme responsible for this is a (Ca2+, Mg2+)-ATPase with Km values for Ca2+ of 30 p,mol dm-3 and 0.3 mmol dm-3, and a molecular weight of 170 000. The enzyme can be crossiinked and co-isolated with a calcium-binding protein.158 Transport of Ca2+ is also associated with (Ca2+, Mg2+)-ATPases in neutrophil plasma membranes,159 transverse tubule membranes from rabbit skeletal muscle,160 rabbit myocardial membrane,161 endoplasmic reticulum,162 sar-colemma,163 brain microsomes,164 the Golgi apparatus165 and rat liver plasma membranes.166... 

Pregnancy and lactation are two critical periods, since the fetus as well as the newborn secure the calcium needed for development of their skeletal system completely from maternal sources - that is, the mother s skeletal system. The organism also has a particular need for calcium during skeletal growth and development in order to achieve an optimal peak bone mass (Johnston et al. 

On the wider scale, ionised calcium in sera measured with the calcium ion-selective electrode have helped in studying the direct effect of calcium on the hyperparathyroidism of chronic renal failure when it was shown that rats on low calcium diet developed larger parathyroids and more severe bone disease at the end of four weeks while diets with above normal calcium levels produced no additional benefits [130]. Other studies include the relation between hypercalcemia and normal ionised serum calcium in a case of myelomatosis [86], the detection of hypocalcemia in susceptible neonates [68], and studies on serum ionised calcium changes following citrated blood transfusion in anaesthetised subjects [93]. The transfusion studies showed six patients during anaesthesia to have a decrease of 0.135 mmol dm" after 500 cm and 0.15 mmol dm" after 1000 cm blood, respectively. However, the calcium ion concentration increased by a mean of 0.075 mmol dm" in 10 min following complete infusion of the blood [93]. 

During development of chicken skeletal muscle cells, the marked increase in Ca transport of sarcoplasmic reticulum, observed both in vivo and in vitro systems, can be interpreted mainly as the result of an increase in the concentration of Ca transport ATPase. Changes in the fatty acid composition of muscle membranes developed in vivo occur with a balance between chain length and unsaturation, without affecting significantly their Ca permeability. In cultured muscle cells their fatty acid composition can be manipulated to a great extent by lipid supplementation of the culture medium. The effects of these in vitro modifications in lipid composition on the calcium transport function of muscle membranes should be investigated. 

Until World War 1 acetone was manufactured commercially by the dry distillation of calcium acetate from lime and pyroligneous acid (wood distillate) (9). During the war processes for acetic acid from acetylene and by fermentation supplanted the pyroligneous acid (10). In turn these methods were displaced by the process developed for the bacterial fermentation of carbohydrates (cornstarch and molasses) to acetone and alcohols (11). At one time Pubhcker Industries, Commercial Solvents, and National Distillers had combined biofermentation capacity of 22,700 metric tons of acetone per year. Biofermentation became noncompetitive around 1960 because of the economics of scale of the isopropyl alcohol dehydrogenation and cumene hydroperoxide processes. 

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