Differences In Magnesium Content Research Articles

Oim mice exhibit altered femur and incisor mineral composition and decreased bone mineral density

To investigate the role of the proα2(I) collagen chains of type I collagen in mineralization we used the oim (osteogenesis imperfecta model) mouse as our model system. The oim/ oim mouse (homozygous for a null mutation in its COL1A2 gene of type I collagen) fails to synthesize functional proα2(I) collagen chains, synthesizing only homotrimers of proα1(I) collagen chains. To evaluate the role of proα2(I) collagen in type I collagen structure/function in mineralized tissues, we examined age-matched oim/ oim, heterozygous ( oim/+), and wild-type (+/+) mouse femurs and incisors for mineral composition (calcium, phosphorus, magnesium, fluoride, sodium, potassium, and chloride) by neutron activation analyses (NAA), and bone mineral content (BMC) and bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) in a longitudinal study (7 weeks to 16 months of age). NAA demonstrated that oim/ oim femurs had significant differences in magnesium, fluoride, and sodium content as compared with +/+ mouse femurs, and oim/ oim teeth had significant differences in magnesium content as compared to +/+ teeth. The ratio of calcium to phosphate was also significantly reduced in the oim/ oim mouse femurs (1.58 ± 0.01) compared with +/+ femurs (1.63 ± 0.01). DEXA demonstrated that oim/ oim mice had significantly reduced BMC and BMD as compared to oim/+ and +/+ mice. Serum and urine calcium, magnesium, and phosphorus levels, and Ca 47 absorption across the gut were equivalent in oim/ oim and +/+ mice, with no evidence of hypercalciuria. These studies suggest that the known decreased biomechanical properties of oim/ oim bone reflect both altered mineral composition as well as the decreased BMD, which further suggests that the presence of α2(I) chains plays an important role in mineralization.

Subcellular Changes in Protein Metabolism and Magnesium Content of the Pancreas in Rats Fed Two Levels of Dietary Protein and Magnesium

Subcellular distribution of magnesium and incorporation of C-valine into proteins of the pancreas were investigated in rats fed 15 or 30% casein diets with 50 or 1,000 ppm magnesium for 10 days. To permit estimates of enzyme synthesis and secretion, rats in all treatment groups were killed in both the fed and fasted states 5, 45, and 120 minutes after injection of C-valine. Microsomal, zymogen, and supernatant fractions were further fractionated into acid-soluble (transportable) and acid-pre- cipitable portions. The niitochondrial and the nuclei and debris fractions were analyzed without further fractionation. Decreased specific activities were observed in the proteins of acid-soluble microsomal fractions, the acid-soluble supernatant fraction, and the total niitochondrial fraction of fasted magnesium-deficient rats 2 hours after injection of labeled valine. Magnesium contents of four of the subcellular fractions were not sig nificantly affected by dietary treatment. Only in the microsomal fraction from fasted and refed rats fed the high proteinâ€highmagnesium diet was the magnesium concentra tion expressed per gram pancreas significantly greater than that in other treatment groups. The difference was not significant when expressed as micrograms magnesium per milligram protein. Magnesium content ( micrograms magnesium per gram pancreas ) of the microsomal, zymogen, and supernatant fractions was generally lower in fasted than in fed rats. Differences in magnesium content and distribution of labeled proteins in fed and fasted animals are discussed in terms of secretion mechanisms. J. Nutr. 104: 1618-1629, 1974.

Chemical composition of organs of children who died from malnutrition.

1. Chemical analysis was carried out on samples of brain, liver, skeletal muscle, heart and kidney obtained from children who died of malnutrition. Total body potassium was measured before autopsy by the ‘whole body counting’ technique.2. There was a marked increase in liver fat, and the brain contributed a higher percentage of the body-weight in the more severely malnourished children.3. All the organs had approximately the same concentrations of non-collagen nitrogen. The proportion of collagen was highest in muscle.4. All organs were depleted of potassium, but the muscle was most severely affected. Brain potassium as a percentage of total body potassium was higher than normal in the most severely potassium depleted children.5. Measurements of tissue magnesium showed that there was no difference in magnesium content of tissues when expressed in terms of non-collagen nitrogen. When compared with normal values, muscle was magnesium depleted. The potassium to magnesium ratio was lowest in muscle.

PROTEIN “SOLUBILIZATION” AND CALCIUM AND MAGNESIUM PRECIPITATION BY “CHLORINATED CLEANERS”

Summary It has been stated that chlorinated cleansers increase the “protein solubilization” properties of cleanser solutions to which they are added (7). Chlorinated cleansers, however, are alkaline materials which increase the active alkalinity of the solutions to which they are added; this seems to have been overlooked. The study reported here was undertaken to determine whether the added available chlorine or the increase in active alkalinity was responsible for the increase in protein solubilization. Two chlorine sources were employed: Sodium hypochlorite (Chlorox) and chlorinated TSP. The approximate amounts by which these chlorine sources increased the active alkalinity (as % NaOH) at the 100 ppm and 200 ppm levels were: Chlorox, 0.0091% and 0.0199%, and chlorinated TSP, 0.0425% and 0.0800%. When the active alkalinity was the same in two solutions , there was no significant difference in the amounts of protein they would dissolve, even though one of the solutions contained available chlorine and the other did not. However, the pairs of solutions containing the same percentage of active alkalinity as the solution containing 200 ppm available chlorine solubilized significantly more protein (p <0.06) than did the pairs which contained the same active alkalinity as the solution containing 100 ppm; this is attributed to the higher active alkalinity of the former. These results were the same whether Chlorox or chlorinated TSP was the chlorine source, whether the direct or indirect method of determining protein solubilization was employed, and in the direct method, whether skim or homogenized milk was the soiling agent. On the basis of these data, the increase in active alkalinity, not the added available chlorine appears responsible for the increase in protein solubilization when a chlorine source is added to an alkaline cleanser. No calcium remained in any of the spent cleansers from the direct method of evaluating protein solubilization. In general, the amount of magnesium remaining decreased as the active alkalinity of the solution increased. There was no significant difference in magnesium content between the chlorine-containing and chlorine-free solutions having the same active alkalinity. Chlorine sources apparently minimize precipitation of hard water cations onto equipment surfaces.