Calcium assimilation

Lactose, when fermented by laclic bacteria, is the source of the lactic acid formed in sour milk and whey. Lactose is helpful in establishing a slightly acid reaction in the intestine, which assists in calcium assimilation. 

Diuretics, by increasing kidney output, deplete calcium, magnesium, potassium, and zinc. This, in turn, depletes energy and lowers immune function. Over-the-counter antacids, as well as the peptic ulcer medication cimetidine, reduce iron and calcium assimilation, vitamin Bj , and intrinsic factor (without which Bi2 can t be absorbed). Drugs prescribed for heart disease reduce libido, and some of them render men impotent. 

The Fermentation Process The process by which this antifungal substance is produced is an aerobic fermentation of an aquaous nutrient medium inoculated with a pimaricin-producing strain of Streptomycesgihrosporeus. The nutrient medium contains an assimilable source of carbon such as starch, molasses, or glycerol, an assimilable source of nitrogen such as corn steep liquor and Inorganic cations such as potassium, sodium or calcium, and anions such as sulfate, phosphate or chloride. Trace elements such as boron, molybdenum or copper are supplied as needed in the form of impurities by the other constituents of the medium. 

Human food, both plant and animal, usually contains satisfactory amounts of zinc to cover the requirement for this metal, which is present within the range of few to several pg per g of product. Zinc deficiencies are usually caused by a reduction of its absorption in the gastrointestinal tract rather than by its lack. Reduction in absorption may be caused by antagonistic activity of cadmium, calcium or phytates. A decrease in assimilation of zinc is also observed among alcoholics. 

When cells of Pseudomonas sp. OS-K-29 immobilized on calcium alginate were incubated in 80 1 of a synthetic medium containing 0.2 vol.% of racemic 2,3-DCP, optically pure (S)-2,3-DCP of 100% e.e. was obtained. The immobilized cells could be re-used for a series of continuous reactions, a bioreactor being used for 19 reactions over 50 days without any loss of activity (Fig. 3). Optically pure (i )-2,3-DCP (100% e.e.) was also isolated from the racemate by means of stereospecific assimilation by Alcaligenes sp. DS-K-S38. Highly pure (R)- and (S)-EP of 99.5% e.e. were prepared from (S)- and (i )-2,3-DCP by treatment with aqueous NaOH, respectively [20-221 (Fig. 2). 

These different casein monomers combine with calcium phosphate to form discrete particles on the nano-size scale. The phosphoserines of the caseins are seemingly clustered for the purpose of linking within the micelle to putative calcium phosphate microcrystallites, also known as nanoclusters (Holt, 1992 Home, 1998, 2002, 2003, 2006 Holt et al., 2003 Home et al., 2007). Structural evidence for the existence of such nanoclusters has come from neutron and X-ray scattering (de Kruif and Holt, 2003 Holt et al., 2003 Pignon et al., 2004 Marchin et al., 2007). The presence of nanoclusters allows native casein micelles to be effective natural suppliers of essential calcium salts in the human diet in a readily assimilated functional form. Protein-nanocluster interactions are the central concept of the cross-linking mechanism in Holt s model of casein micellar assembly (Holt et al., 2003 de Kruif and Holt, 2003). Any analogy with conventional soap-like micelles is considered to be... 

Of nutrient chelates in the human diet, oxalates and phytules arc Ihe most common. Oxalic acid, found principally in spinach, rhubarb leaves, beet leaves, some fruits, and mushrooms, is u primary chelator of calcium. Oxalate present in pineapple, kiwifmil, and possibly in other foods, occurs as calcium oxalale. CaCiOj. This compound is in the form of needle-like crystals, known as raphidcs. which can produce painful sensations in the mouth when eaten raw. The effects of oxalic acid in the diet may he twofold. First, it forms strong chelates with dietary calcium, rendering the culcium unavailable for absorption and assimilation. Secondly, absorbed oxalic acid causes assimilated Ca to be precipitated as insoluble salts that accumulate in the renal glomeruli and contribute to the formation of renal calculi. 

Phosphate fertilizers. From the extensive phosphate rock deposits in Tennessee, South Carolina, Florida, Idaho, and Montana, approximately 3 million tons of ore are used annually in the manufacture of fertilizers. The chief phosphate present in this rock is the normal calcium salt [Ca3(P04)2]. Because of its insolubility, this compound is not very useful as a fertilizer. If a phosphorus compound is to provide phosphorus that can be assimilated by growing plants, the compound must be one that is appreciably soluble. 

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