Apparent copper absorption from a vegetarian diet.
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BACKGROUND: Vegetarian diets often contain more copper than do nonvegetarian diets, but observations of decreased plasma copper associated with vegetarian diets suggest that these diets have lower copper bioavailability than do nonvegetarian diets. OBJECTIVE: Our objective was to determine apparent copper absorption from controlled lactoovovegetarian and nonvegetarian diets. DESIGN: Eighteen women aged 20-43 y consumed lactoovovegetarian and nonvegetarian weighed diets for 8 wk each in a randomized, crossover design. The lactoovovegetarian and nonvegetarian diets provided 1.45 and 0.94 mg Cu, 38 and 16 g dietary fiber, and 1584 and 518 mg phytic acid, respectively, per 9.2 MJ (2200 kcal). After the women had been consuming each diet for 4 wk, their apparent copper absorption was determined by measuring the fecal excretion of the 65Cu stable isotope, extrinsically added to the entire menu as 65CuCl2. RESULTS: Plasma copper and ceruloplasmin were not affected by diet. The efficiency of apparent copper absorption from the lactoovovegetarian diet was less (33%) than that from the nonvegetarian diet (42%) (pooled SD: 9%; P < 0.05). However, because the lactoovovegetarian diet contained approximately 50% more copper, the total apparent copper absorption from the lactoovovegetarian diet (0.48 mg/d) was greater than that from the nonvegetarian diet (0.40 mg/d) (pooled SD: 0.09 mg; P < 0.05). CONCLUSION: Although copper was less efficiently absorbed from a vegetarian diet than from a nonvegetarian diet, total apparent copper absorption was greater from the vegetarian diet because of its greater copper content. (+info)
Low-phytic acid corn improves nutrient utilization for growing pigs.
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Thirty-five crossbred barrows averaging 14.5 kg initial BW were used in a 5-wk experiment to compare the P availability and nutritional value of a low-phytate hybrid corn (LPC, 0.26% total P, 0.08% phytic acid P) homozygous for the lpa 1-1 allele with a nearly isogenic normal hybrid corn (NC, 0.25% total P, 0.20% phytic acid P). The pigs were fed individually twice daily in metabolism pens. Three semipurified diets were created in which corn was the only source of phytate. Diet 1 contained 72% NC, 0.15% estimated available P (aP) and 0.55% Ca. Diet 2 contained 72% LPC, 0.24% aP, and 0.55% Ca. The only differences between Diets 1 and 2 were the source of corn and the levels of aP. No inorganic P (iP) was added to these diets in order to measure the animal response to the different levels of aP in the corn hybrids. Diet 3 was NC Diet 1 supplemented with iP to equal the level of aP in LPC Diet 2. Diets 4 and 5 were practical corn-soybean meal diets formulated with each corn to meet all minimum nutrient requirements and contained 0.30% aP and 0.65% Ca. For the semipurified diets, pigs fed LPC Diet 2 had higher (P < 0.01) growth performance, bone breaking strength, P absorption and retention, Ca absorption and retention, and N retention than pigs fed NC Diet 1. However, when the NC diet was supplemented with iP to equal the aP in the LPC diet, most criteria were similar (P > or = 0.2), indicating an equal nutritional value for both corn hybrids after adjusting for phytate level. The only treatment difference, other than P excretion, between the practical corn diets supplemented with soybean meal was a higher (P < 0.05) bone breaking strength for pigs fed LPC Diet 5 compared with NC Diet 4. The use of LPC in pig diets reduced P excretion in swine waste by 50 and 18.4% in the semipurified and practical diets, respectively, compared with NC. Using our in vitro procedure designed to simulate the digestive system of the pig, the availability of P for pigs was estimated at 56% for LPC and 11% for NC. (+info)
Binding of inositol hexakisphosphate (IP6) to Ku but not to DNA-PKcs.
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The nonhomologous DNA end joining (NHEJ) pathway is responsible for repairing a major fraction of double strand DNA breaks in somatic cells of all multicellular eukaryotes. As an indispensable protein in the NHEJ pathway, Ku has been hypothesized to be the first protein to bind at the DNA ends generated at a double strand break being repaired by this pathway. When bound to a DNA end, Ku improves the affinity of another DNA end-binding protein, DNA-PK(cs), to that end. The Ku.DNA-PK(cs) complex is often termed the DNA-PK holoenzyme. It was recently shown that myo-inositol hexakisphosphate (IP(6)) stimulates the joining of complementary DNA ends in a cell free system. Moreover, the binding data suggested that IP(6) bound to DNA-PK(cs) (not to Ku). Here we clearly show that, in fact, IP(6) associates not with DNA-PK(cs), but rather with Ku. Furthermore, the binding of DNA ends and IP(6) to Ku are independent of each other. The possible relationship between inositol phosphate metabolism and DNA repair is discussed in light of these findings. (+info)
Biochemical and molecular characterization of a mutation that confers a decreased raffinosaccharide and phytic acid phenotype on soybean seeds.
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A single, recessive mutation in soybean (Glycine max L. Merr.), which confers a seed phenotype of increased inorganic phosphate, decreased phytic acid, and a decrease in total raffinosaccharides, has been previously disclosed (S.A. Sebastian, P.S. Kerr, R.W. Pearlstein, W.D. Hitz [2000] Soy in Animal Nutrition, pp 56-74). The genetic lesion causing the multiple changes in seed phenotype is a single base change in the third base of the codon for what is amino acid residue 396 of the mature peptide encoding a seed-expressed myo-inositol 1-phospate synthase gene. The base change causes residue 396 to change from lysine to asparagine. That amino acid change decreases the specific activity of the seed-expressed myo-inositol 1-phosphate synthase by about 90%. Radio tracer experiments indicate that the supply of myo-inositol to the reaction, which converts UDP-galactose and myo-inositol to galactinol is a controlling factor in the conversion of total carbohydrate into the raffinosaccharides in both wild-type and mutant lines. That same decrease in myo-inositol 1-phosphate synthetic capacity leads to a decreased capacity for the synthesis of myo-inositol hexaphosphate (phytic acid) and a concomitant increase in inorganic phosphate. (+info)
myo-Inositol hexakisphosphate is a major component of an extracellular structure in the parasitic cestode Echinococcus granulosus.
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myo-Inositol hexakisphosphate (IP(6)) is an abundant intracellular component of animal cells. In this study we describe the presence of extracellular IP(6) in the hydatid cyst wall (HCW) of the larval stage of the cestode parasite Echinococcus granulosus. The HCW comprises an inner cellular layer and an outer, acellular (laminated) layer up to 2 mm in thickness that protects the parasite from host immune cells. A compound, subsequently identified as IP(6), was detected in and purified from an HCW extract on the basis of its capacity to inhibit complement activation. The identification of the isolated compound was carried out by a combination of NMR, MS and TLC. The majority of IP(6) in the HCW was found in the acellular layer, with only a small fraction of the compound being extracted from cells. In the laminated layer, IP(6) was present in association with calcium, and accounted for up to 15% of the total dry mass of the HCW. IP(6) was not detected in any other structures or stages of the parasite. Our results imply that IP(6) is secreted by the larval stage of the parasite in a polarized fashion towards the interface with the host. This is the first report of the secretion of IP(6), and the possible implications beyond the biology of E. granulosus are discussed. (+info)
Progress in breeding low phytate crops.
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Populations that depend on grains and legumes as staple foods consume diets rich in phytic acid (myo-inositol-1,2,3,4,5,6-hexkisphosphate), the storage form of phosphorus in seeds. This compound binds tightly to important mineral nutrients such as iron and zinc, forming salts that are largely excreted. This phenomenon can contribute to mineral depletion and deficiency. As one approach to solving this and environmental problems associated with seed-derived dietary phytic acid, the U. S. Department of Agriculture and others have isolated cereal and legume low-phytic acid mutations and have used these to breed first-generation low-phytate hybrids, cultivars and lines of maize (Zea mays), barley (Hordeum vulgare), rice (Oryza sativa) and soybean (Glycine max). Seed phytic acid is reduced in these crops by 50-95%. The progress in the genetics, breeding and nutritional evaluation of low-phytate crops are reviewed in this article. (+info)
Transgenic approaches in commonly consumed cereals to improve iron and zinc content and bioavailability.
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Modern genetic and molecular technologies provide a number of tools that can be utilized for the development of staple foods with a higher iron and zinc content and improved bioavailability of these minerals. This article summarizes current strategies aimed at increasing the iron-sequestering capacity of the endosperm and improving mineral bioavailability via in planta synthesis of microbial phytases. A case study is presented for wheat, and future strategies are discussed addressing the importance of phytase thermostability. (+info)
Quantitation of liver and spleen uptake of (99m)Tc-phytate colloid using SPECT: detection of liver cirrhosis.
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The purpose of this study was to assess the diagnostic performance of quantitative SPECT of (99m)Tc-phytate colloid in detecting liver cirrhosis and to assess the correlation between the SPECT results and the severity of disease. METHODS: Quantitative SPECT was performed on 60 patients (38 men, 22 women; mean age, 62.4 y) with liver cirrhosis and 36 control patients (21 men, 15 women; mean age, 58.7 y) without liver cirrhosis, and the results for the 2 groups were compared. Correlation with Child--Pugh classification and receiver operating characteristic methodology was used to analyze the results. RESULTS: Cirrhotic livers had a lower total uptake than did control livers (35.6% plus minus 13.5% vs. 61.6% +/- 10.2%, P < 0.0001). This reduced uptake was associated with a significantly reduced percentage injected dose per cubic centimeter (%ID/cm(3)) (0.024 +/- 0.01 vs. 0.044 +/- 0.01, P < 0.0001). The volume, 1,467 +/- 348 cm(3), was similar to that of control livers (1,487 +/- 397 cm(3), P = 0.80). Total uptake in the spleen was significantly greater in patients with cirrhosis than in control patients (24.9% +/- 12% vs. 7.6% +/- 3.2%, P < 0.0001) because of an increased volume (833 +/- 460 cm(3) vs. 239 +/- 90 cm(3), P < 0.0001). The %ID/cm(3) of spleen tissue was 0.033 +/- 0.01, which was similar to the value in control patients (0.032 +/- 0.01, P = 0.88). Spleen volume showed the best performance in detecting liver cirrhosis, with a mean area under the curve of 0.97 (95% CI = 0.91--0.99). The severity of liver disease correlated better with total liver uptake (r = -0.68, 95% CI = -0.80 to -0.52, P < 0.0001). CONCLUSION: Individual SPECT quantitation of (99m)Tc-phytate colloid uptake in the liver and spleen could be used as a noninvasive method to separate normal from cirrhotic livers and to evaluate the severity of disease. (+info)