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1.
The Percentage of Dietary Phosphorus Excreted in the Urine Varies by Dietary Pattern in a Randomized Feeding Study in Adults.
McClure, ST, Rebholz, CM, Phillips, KM, Champagne, CM, Selvin, E, Appel, LJ
The Journal of nutrition. 2019;(5):816-823
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Abstract
BACKGROUND Urinary phosphorus excretion has been proposed as a recovery biomarker of dietary phosphorus intake. However, it is unclear whether phosphorus excretion is constant across a range of dietary and nondietary factors. OBJECTIVE We assessed whether percentage urinary phosphorus excretion is constant across 3 dietary patterns in the Dietary Approaches to Stop Hypertension (DASH) trial. METHODS DASH is a completed feeding study of 459 prehypertensive and stage 1 hypertensive adults (52% male, 56% black). After a 3-wk run-in on a typical American (control) diet, participants were randomly assigned to the control diet, a diet rich in fruits and vegetables (FV diet), or a diet rich in fruits, vegetables, and low-fat dairy with reduced saturated fat and cholesterol (DASH diet) for 8 wk. We estimated the percentage phosphorus excretion as urinary phosphorus excretion (from 24 h urine) divided by phosphorus intake (from analyzed food composites). Differences between group means for all 3 diets were compared by ANOVA followed by pairwise comparisons with Tukey's honest significant difference test. RESULTS At the end of the intervention, the mean phosphorus intake was 1176 mg/d (95% CI: 1119, 1233 mg/d), 1408 mg/d (1352, 1464 mg/d), and 2051 mg/d (1994, 2107 mg/d) in the control, FV, and DASH diet, respectively (P < 0.001, all comparisons). The mean phosphorus excretion was 734 mg/d (682, 787 mg/d), 705 mg/d (654, 756 mg/d), and 872 mg/d (820, 923 mg/d) in the control, FV, and DASH diet, respectively (P = 0.74 control vs. FV, P < 0.001 all other comparisons). The mean percentage phosphorus excretion was 63% (60%, 67%), 51% (48%, 54%), and 43% (39%, 46%) in the control, FV, and DASH diet, respectively (P < 0.001, all comparisons). CONCLUSIONS These findings in prehypertensive and stage 1 hypertensive adults strongly suggest that urinary phosphorus excretion should not be used as a recovery biomarker for dietary phosphorus intake, given the wide range of urinary phosphorus excretion across dietary patterns. This trial is registered at clinicaltrials.gov as NCT0000054.
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Absolute Quantification of Phosphor-Containing Metabolites in the Liver Using 31 P MRSI and Hepatic Lipid Volume Correction at 7T Suggests No Dependence on Body Mass Index or Age.
Pfleger, L, Gajdošík, M, Wolf, P, Smajis, S, Fellinger, P, Kuehne, A, Krumpolec, P, Trattnig, S, Winhofer, Y, Krebs, M, et al
Journal of magnetic resonance imaging : JMRI. 2019;(2):597-607
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Abstract
BACKGROUND Hepatic disorders are often associated with changes in the concentration of phosphorus-31 (31 P) metabolites. Absolute quantification offers a way to assess those metabolites directly but introduces obstacles, especially at higher field strengths (B0 ≥ 7T). PURPOSE To introduce a feasible method for in vivo absolute quantification of hepatic 31 P metabolites and assess its clinical value by probing differences related to volunteers' age and body mass index (BMI). STUDY TYPE Prospective cohort. SUBJECTS/PHANTOMS Four healthy volunteers included in the reproducibility study and 19 healthy subjects arranged into three subgroups according to BMI and age. Phantoms containing 31 P solution for correction and validation. FIELD STRENGTH/SEQUENCE Phase-encoded 3D pulse-acquire chemical shift imaging for 31 P and single-volume 1 H spectroscopy to assess the hepatocellular lipid content at 7T. ASSESSMENT A phantom replacement method was used. Spectra located in the liver with sufficient signal-to-noise ratio and no contamination from muscle tissue, were used to calculate following metabolite concentrations: adenosine triphosphates (γ- and α-ATP); glycerophosphocholine (GPC); glycerophosphoethanolamine (GPE); inorganic phosphate (Pi ); phosphocholine (PC); phosphoethanolamine (PE); uridine diphosphate-glucose (UDPG); nicotinamide adenine dinucleotide-phosphate (NADH); and phosphatidylcholine (PtdC). Correction for hepatic lipid volume fraction (HLVF) was performed. STATISTICAL TESTS Differences assessed by analysis of variance with Bonferroni correction for multiple comparison and with a Student's t-test when appropriate. RESULTS The concentrations for the young lean group corrected for HLVF were 2.56 ± 0.10 mM for γ-ATP (mean ± standard deviation), α-ATP: 2.42 ± 0.15 mM, GPC: 3.31 ± 0.27 mM, GPE: 3.38 ± 0.87 mM, Pi : 1.42 ± 0.20 mM, PC: 1.47 ± 0.24 mM, PE: 1.61 ± 0.20 mM, UDPG 0.74 ± 0.17 mM, NADH 1.21 ± 0.38 mM, and PtdC: 0.43 ± 0.10 mM. Differences found in ATP levels between lean and overweight volunteers vanished after HLVF correction. DATA CONCLUSION Exploiting the excellent spectral resolution at 7T and using the phantom replacement method, we were able to quantify up to 10 31 P-containing hepatic metabolites. The combination of 31 P magnetic resonance spectroscopy imaging data acquisition and HLVF correction was not able to show a possible dependence of 31 P metabolite concentrations on BMI or age, in the small healthy population used in this study. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:597-607.
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Chemical Forms and Health Risk of Cadmium in Water Spinach Grown in Contaminated Soil with an Increased Level of Phosphorus.
Lam, CM, Chen, KS, Lai, HY
International journal of environmental research and public health. 2019;(18)
Abstract
(1) Background: Even in croplands with a low concentration of cadmium (Cd), there is still a risk for planting crops because of the high accumulation capacity of some leafy vegetables. (2) Methods: In this study, water spinach was planted in four main soil series (Wa, Eh, Tk, and Yu) in central Taiwan, which were spiked with Cd. The soil available phosphorous content was increased to 10-17 mg/kg, and the accumulation and developed chemical forms of Cd were analyzed. (3) Results: The experimental results showed that addition of phosphorous to Wa and Eh promoted the growth of water spinach. Accumulation and upward translocation of Cd were also increased in the phosphorus treatment compared with the control. The addition of phosphorus increased the percentage of Cd compartmentalized in undissolved Cd phosphate, which revealed that the mobility and toxicity of Cd were reduced in the phosphorus treatment. However, most of the water spinach was not edible because the vegetable-induced hazard quotient, which was calculated using three methods, showed hazardous potential in general.
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Denosumab Improves Glomerular Filtration Rate in Osteoporotic Patients With Normal Kidney Function by Lowering Serum Phosphorus.
Miyaoka, D, Inaba, M, Imanishi, Y, Hayashi, N, Ohara, M, Nagata, Y, Kurajoh, M, Yamada, S, Mori, K, Emoto, M
Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 2019;(11):2028-2035
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Abstract
Higher serum phosphorus (Pi) increases the risk for chronic kidney disease (CKD). It was reported that a single administration of denosumab or zoledronate significantly suppressed serum Pi levels as well as those of bone resorption markers in serum. Also, previous evidences suggest a link between bone anti-resorptive therapy and vasoprotective/renoprotective effects through mechanisms that remain unexplored. The aim of this study is to assess the renoprotective effect of denosumab and involvement of denosumab-induced reduction in serum Pi in osteoporotic patients. Osteoporotic patients (n = 73) without overt proteinuria in dipstick test results were treated with denosumab (60 mg) every 6 months during the study period (24 months). Estimated glomerular filtration rate based on serum cystatin C (eGFRcys) was used as a filtration marker and tartrate-resistant acid phosphatase-5b (TRACP-5b) as a bone resorption marker. For analysis of non-CKD patients (n = 56), those with eGFRcys <60 mL/min/1.73 m2 were excluded. A single injection of denosumab suppressed serum Pi as well as TRACP-5b during the first 6 months, whereas age-related decline in eGFRcys was significantly reversed, with an increase of 2.75 ± 1.2 mL/min/1.73 m2 after 24 months noted. Multivariate analysis showed that serum Pi reduction following the initial denosumab injection was positively associated with serum TRACP-5b suppression during that same period (β = 0.241, p = 0.049). In addition, a positive association of serum Pi suppression, but not of corrected calcium or TRACP-5b, with eGFRcys increase after 24 months (β = 0.321, p = 0.014) was found after adjustments for gender, age, BMI, antihypertensive drug use, albumin, and eGFRcys. The same was observed in osteoporotic cases restricted to non-CKD patients. In conclusion, serum Pi reduction resulting from phosphorus load decrement from bone induced by denosumab is a determinant for eGFRcys increase. Early introduction of bone antiresorptive therapy can retain glomerular filtration in osteoporosis cases, including non-CKD patients. © 2019 American Society for Bone and Mineral Research.
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The role of phosphate-containing medications and low dietary phosphorus-protein ratio in reducing intestinal phosphorus load in patients with chronic kidney disease.
Li, J, Wang, L, Han, M, Xiong, Y, Liao, R, Li, Y, Sun, S, Maharjan, A, Su, B
Nutrition & diabetes. 2019;(1):14
Abstract
Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication in patients experiencing end-stage renal disease (ESRD). It includes abnormalities in bone and mineral metabolism and vascular calcification. Hyperphosphatemia is a major risk factor leading to morbidity and mortality in patients with chronic kidney disease. Increased mortality has been observed in patients with ESRD, with serum phosphorus levels of >5.5 mg/dL. Therefore, control of hyperphosphatemia is a major therapeutic goal in the prevention and treatment of CKD-MBD. The treatment of hyperphosphatemia includes decreasing intestinal phosphorus load and increasing renal phosphorus removal. Decreasing the intestinal load of phosphorus plays a major role in the prevention and treatment of CKD-MBD. Among the dietary sources of phosphorus, some of the commonly prescribed medications have also been reported to contain phosphorus. However, drugs are often ignored even though they act as a potential source of phosphorus. Similarly, although proteins are the major source of dietary phosphorus, reducing protein intake can increase mortality in patients with CKD. Recently, the importance of phosphorus/protein ratio in food have been reported to be a sensitive marker for controlling dietary intake of phosphorus. This review summarizes the progress in the research on phosphate content in drugs as an excipient and the various aspects of dietary management of hyperphosphatemia in patients with CKD, with special emphasis on dietary restriction of phosphorus with low dietary phosphate/protein ratio.
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How Does Evolution in Phosphorus-Impoverished Landscapes Impact Plant Nitrogen and Sulfur Assimilation?
Prodhan, MA, Finnegan, PM, Lambers, H
Trends in plant science. 2019;(1):69-82
Abstract
Phosphorus (P) fertilisers, made from rock phosphate, are used to attain high crop yields. However, rock phosphate is a finite resource and excessive P fertilisers pollute our environment, stressing the need for more P-efficient crops. Some Proteaceae have evolved in extremely P-impoverished environments. One of their adaptations is to curtail the abundance of ribosomal RNA, and thus protein, and tightly control the acquisition and assimilation of nitrogen (N) and sulfur. This differs fundamentally from plants that evolved in environments where N limits plant productivity, but is likely common in many species that evolved in P-impoverished landscapes. Here, we scrutinise the relevance of these responses towards developing P-efficient crops, focusing on plant species where 'P is in the driver's seat'.
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The Role of the Phosphorus Atom in Drug Design.
Rodriguez, JB, Gallo-Rodriguez, C
ChemMedChem. 2019;(2):190-216
Abstract
Although the phosphorus atom is found in a variety of oxidation states, most of the phosphorus-containing molecules of pharmacological importance possess phosphorus in the form of phosphonate or phosphinate functional groups, or in a major oxidation state as a phosphate group. The most common occurrence of phosphorus in drugs is either in prodrugs or in compounds for which the phosphorus atom plays a role in the biological activity, such as in modified nucleotides, in metabolically stable analogues of metabolites bearing phosphate groups, and as bioisosteric analogues of carboxyl groups.
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[Decomposition of Myriophyllum aquaticum and the Associated Release of Nitrogen and Phosphorus].
Tong, X, Luo, P, Liu, F, Huang, M, Chen, Z, Xiao, RL, Wu, JS
Huan jing ke xue= Huanjing kexue. 2019;(7):3118-3125
Abstract
Decomposition of wetland plants could release pollutants, which may affect the removal efficiency and effluent quality of constructed wetlands. The experimental decomposition test of Myriophyllum aquaticum was carried out for 60 d using nylon bags, and release characteristics of nitrogen and phosphorus during the decomposition process were studied. The results showed that the decomposition rate of M. aquaticum was fastest during the first 0-4 d, with a weight loss of 30%, while the degradation rate slowed gradually during the period 4-60 d, with weight loss of 31%. The fitting first-order kinetic decomposition rate constant was 0.0142 d-1, and the calculated time to degrade 50% of dry matter was 48.8 d. The water pH decreased rapidly from 7.60 to 5.63 during 0-4 d, stabilized during 4-32 d, and finally increased to 7.03 (which was close to the control sample without M. aquaticum). The dissolved oxygen concentration decreased rapidly from 6.30 mg·L-1 to 0.61 mg·L-1 during 0-4 d, and remained in an anaerobic state. The total nitrogen concentration in the water increased rapidly to 12.7 mg·L-1 within 2 h, gradually decreased to 5.80 mg·L-1 during 2 h-32 d, and then finally increased slightly. The phosphorus concentration increased rapidly to 18.4 mg·L-1 at the beginning of the experiment, and then gradually stabilized. The main forms of nitrogen and phosphorus released by M. aquaticum were organic nitrogen (accounting for 65.7%-94.7% of total nitrogen) and inorganic phosphorus (accounting for 61%-89% of total phosphorus), respectively. The total nitrogen content of M. aquaticum increased from 24.3 mg·g-1 to 60.5 mg·g-1 with increasing degradation time; the total phosphorus decreased initially from 6.09 mg·g-1 to 2.94 mg·g-1 and then remained constant. These trends may have been related to the fixation of nitrogen by attached microorganisms. Therefore, suitable harvesting and management strategies should be adopted for wetland plants to reduce secondary pollution.
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Transcriptome analysis in roots and leaves of wheat seedlings in response to low-phosphorus stress.
Wang, J, Qin, Q, Pan, J, Sun, L, Sun, Y, Xue, Y, Song, K
Scientific reports. 2019;(1):19802
Abstract
Low phosphorus availability is a major abiotic factor constraining wheat growth. The molecular mechanisms of the wheat whole genome under low-phosphorus stress are still unclear. To obtain information on gene expression in wheat seedlings under low-phosphorus stress, transcriptome sequencing was performed on roots and leaves. The results showed that 2,318 (1,646 upregulated and 672 downregulated) transcripts were differentially expressed in the leaves, and 2,018 (1,310 upregulated and 708 downregulated) were differentially expressed in the roots. Further analysis showed that these differentially expressed genes (DEGs) were mainly enriched in carbon fixation in photosynthetic organs and in carbon metabolism, photosynthesis, glyoxylate and dicarboxylate metabolism and plant-pathogen interaction in both leaves and roots. These pathways were mainly associated with environmental adaptation, energy metabolism and carbohydrate metabolism, suggesting that the metabolic processes were strengthened in wheat seedlings under low-phosphorus stress and that more energy and substances were produced to resist or adapt to this unfavourable environment. This research might provide potential directions and valuable resources to further study wheat under low-phosphorus stress.
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Piezoresistivity of InAsP Nanowires: Role of Crystal Phases and Phosphorus Atoms in Strain-Induced Channel Conductances.
Kim, I, Kim, HS, Ryu, H
Molecules (Basel, Switzerland). 2019;(18)
Abstract
Strong piezoresistivity of InAsP nanowires is rationalized with atomistic simulations coupled to Density Functional Theory. With a focal interest in the case of the As(75%)-P(25%) alloy, the role of crystal phases and phosphorus atoms in strain-driven carrier conductance is discussed with a direct comparison to nanowires of a single crystal phase and a binary (InAs) alloy. Our analysis of electronic structures presents solid evidences that the strong electron conductance and its sensitivity to external tensile stress are due to the phosphorous atoms in a Wurtzite phase, and the effect of a Zincblende phase is not remarkable. With several solid connections to recent experimental studies, this work can serve as a sound framework for understanding of the unique piezoresistive characteristics of InAsP nanowires.