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Serum phosphate and mortality in incident dialysis patients in Australia and New Zealand.
Tiong, MK, Ullah, S, McDonald, SP, Tan, SJ, Lioufas, NM, Roberts, MA, Toussaint, ND
Nephrology (Carlton, Vic.). 2021;(10):814-823
Abstract
AIM: Hyperphosphataemia is associated with increased adverse outcomes, including mortality. Re-examining this association using up-to-date data reflecting current and real-world practices, across different global regions and in both haemodialysis and peritoneal dialysis patients, is important. METHODS We describe the association between serum phosphate and all-cause and cardiovascular mortality in incident dialysis patients between 2008 and 2018 using the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. Time-dependent Cox proportionate hazards models were used. Models were adjusted for available covariates and fitted for the overall cohort, and also each dialysis modality. RESULTS 31 989 patients were followed over 97 122 person-years at risk (mean age at first dialysis 61 years, 38% female, 67% haemodialysis). We observed a U-shaped association between serum phosphate and all-cause mortality. In the fully adjusted model, categories of serum phosphate above and below 1.25-1.99 mmol/L were associated with progressively higher risk, reaching a hazard ratio of 2.13 (95% CI 1.93-2.36, p < .001) for serum phosphate ≥2.75 mmol/L, and 1.56 (95% CI 1.44-1.69, p < .001) for serum phosphate <1.00 mmol/L. Low and high levels of serum phosphate were also associated with increased risk of cardiovascular mortality, however the association with high serum phosphate was more pronounced ("J-shaped relationship"). The associations were consistent across sub-analyses of patients receiving haemodialysis and peritoneal dialysis treatment. CONCLUSION In this large contemporary dialysis cohort, both high and low levels of serum phosphate were independently associated with increased risk of mortality. Future studies are required to determine whether treatment of abnormal serum phosphate levels improves mortality.
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Multiple origins of Indian dwarf wheat by mutations targeting the TREE domain of a GSK3-like kinase for drought tolerance, phosphate uptake, and grain quality.
Gupta, A, Hua, L, Lin, G, Molnár, I, Doležel, J, Liu, S, Li, W
TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik. 2021;(2):633-645
Abstract
Multiple origins of Indian dwarf wheat were due to two mutations targeting the same TREE domain of a GSK3-like kinase, and these mutations confer to enhanced drought tolerance and increased phosphate and nitrogen accumulation for adaptation to the dry climate of Indian and Pakistan. Indian dwarf wheat, featured by the short stature, erect leaves, dense spikes, and small, spherical grains, was a staple crop in India and Pakistan from the Bronze Age until the early 1900s. These morphological features are controlled by a single locus Sphaerococcum 1 (S1), but the genetic identity of the locus and molecular mechanisms underlying the selection of this wheat type are unknown. In this study, we showed that the origin of Indian dwarf wheat was due to two independent missense mutations targeting the conserved TREE domain of a GSK3-like kinase, which is homologous to the Arabidopsis BIN2 protein, a negative regulator in brassinosteroid signaling. The S1 protein is involved in brassinosteroid signaling by physical interaction with the wheat BES1/BZR1 proteins. The dwarf alleles are insensitive to brassinosteroid, upregulates brassinosteroid biosynthetic genes, significantly enhanced drought tolerance, facilitated phosphate accumulation, and increased high molecular weight glutenins. It is the enhanced drought tolerance and accumulation of nitrogen and phosphate that contributed to the adaptation of such a small-grain form of wheat to the dry climate of India and Pakistan. Thus, our research not only identified the genetic events underlying the origin of the Indian dwarf wheat, but also revealed the function of brassinosteroid in the regulation of drought tolerance, phosphate homeostasis, and grain quality.
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Phosphate Concentrations and Modifying Factors in Healthy Children From 12 to 24 Months of Age.
Koljonen, L, Enlund-Cerullo, M, Hauta-Alus, H, Holmlund-Suila, E, Valkama, S, Rosendahl, J, Andersson, S, Pekkinen, M, Mäkitie, O
The Journal of clinical endocrinology and metabolism. 2021;(10):2865-2875
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Abstract
CONTEXT Phosphate homeostasis and its modifiers in early childhood are inadequately characterized. OBJECTIVE To determine physiological plasma phosphate concentration and modifying factors in healthy infants at 12 to 24 months of age. DESIGN This study included 525 healthy infants (53% girls), who participated in a randomized vitamin D intervention trial and received daily vitamin D3 supplementation of either 10 or 30 μg from age 2 weeks to 24 months. Biochemical parameters were measured at 12 and 24 months. Dietary phosphate intake was determined at 12 months. MAIN OUTCOME MEASURES Plasma phosphate concentrations at 12 and 24 months of age. RESULTS Mean (SD) phosphate concentration decreased from 12 months (1.9 ± 0.15 mmol/L) to 24 months (1.6 ± 0.17 mmol/L) of age (P < 0.001 for repeated measurements). When adjusted by covariates, such as body size, creatinine, serum 25-hydroxyvitamin D, intact and C-terminal fibroblast growth factor 23, mean plasma phosphate was higher in boys than girls during follow-up (P = 0.019). Phosphate concentrations were similar in the vitamin D intervention groups (P > 0.472 for all). Plasma iron was associated positively with plasma phosphate at both time points (B, 0.006 and 0.005; 95% CI, 0.004-0.009 and 0.002-0.008; P < 0.001 at both time points, respectively). At 24 months of age, the main modifier of phosphate concentration was plasma creatinine (B, 0.007; 95% CI 0.003-0.011, P < 0.001). CONCLUSION Plasma phosphate concentration decreased from age 12 to 24 months. In infants and toddlers, the strongest plasma phosphate modifiers were sex, iron, and creatinine, whereas vitamin D supplementation did not modify phosphate concentrations.
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Calcium-phosphate homeostasis in secondary progressive multiple sclerosis patients during mitoxantrone therapy.
Lis, M, Niedziela, N, Nowak-Kiczmer, M, Kubicka-Bączyk, K, Adamczyk-Sowa, M
Neurological research. 2021;(12):1050-1055
Abstract
OBJECTIVES To assess calcium-phosphate parameters in SPMS patients treated with mitoxantrone (MTX). METHODS Thirty eight SPMS patients eligible for MTX therapy in the Department of Neurology in Zabrze, Poland were enrolled in a prospective study from March 2016 to November 2019. The parameters of serum calcium-phosphate metabolism and the neurological status according to the Expanded Disability Status Scale (EDSS) were assessed. In patients with hypovitaminosis D, vitamin D (VitD) supplementation was introduced (4000 IU/day for 1 month and later 2000 IU /day). RESULTS Most patients were women [57.89%]. The mean age [years] was 56.11 (±7.74). The median time from diagnosis to inclusion day (ID) was 7.50 [4.00-14.00] [years]. Due to VitD supplementation, an increase in serum VitD was observed during the study. 84.21% of patients presented with hypovitaminosis D before MTX treatment compared to 47.37% after treatment. Before MTX therapy, none of the patients underwent surgical repair of the fracture compared to 42.11% of patients after MTX treatment (p < 0.01). DISCUSSION Deficiency of VitD was observed at the baseline in most SPMS patients eligible for MTX therapy. Due to adverse reactions to MTX treatment, this therapy requires patient compliance, cautious drug administration and monitoring during the therapy.
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Translation of Nutrient Level Recommendations to Control Serum Phosphate Into Food-Based Advice.
Byrne, FN, Gillman, B, Kiely, M, Bowles, M, Connolly, P, Earlie, J, Murphy, J, Rennick, T, Reilly, EO, Shiely, F, et al
Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation. 2021;(1):43-48
Abstract
The control of hyperphosphatemia is key to the management of chronic kidney disease mineral and bone disorder. Dietary restriction of phosphorus is essential to control hyperphosphatemia. Guidelines for chronic kidney disease and end-stage kidney disease generally provide high-level guidance on whether a nutrient should be restricted e.g, restrict dietary phosphorus. Dietitians translate such guidance into nutrient-based strategies and finally into food-based practical dietary advice for patients to follow. The practical aspects of dietary advice are not well described in the literature, neither are the challenges of concurrently altering 1 nutrient e.g., phosphorus while continuing to restrict others e.g., potassium, while maintaining overall nutritional adequacy and quality of life. In this article, we describe how we translated updated nutrient level recommendations into practical dietary advice to be delivered at the bedside.
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Intracellular phosphate sensing and regulation of phosphate transport systems in plants.
Wang, Z, Kuo, HF, Chiou, TJ
Plant physiology. 2021;(4):2043-2055
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Abstract
Recent research on the regulation of cellular phosphate (Pi) homeostasis in eukaryotes has collectively made substantial advances in elucidating inositol pyrophosphates (PP-InsP) as Pi signaling molecules that are perceived by the SPX (Syg1, Pho81, and Xpr1) domains residing in multiple proteins involved in Pi transport and signaling. The PP-InsP-SPX signaling module is evolutionarily conserved across eukaryotes and has been elaborately adopted in plant Pi transport and signaling systems. In this review, we have integrated these advances with prior established knowledge of Pi and PP-InsP metabolism, intracellular Pi sensing, and transcriptional responses according to the dynamics of cellular Pi status in plants. Anticipated challenges and pending questions as well as prospects are also discussed.
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Modification and Validation of the Phosphate Removal Model: A Multicenter Study.
Zhang, W, Du, Q, Xiao, J, Bi, Z, Yu, C, Ye, Z, Wang, M, Chen, J
Kidney & blood pressure research. 2021;(1):53-62
Abstract
BACKGROUND Our research group has previously reported a noninvasive model that estimates phosphate removal within a 4-h hemodialysis (HD) treatment. The aim of this study was to modify the original model and validate the accuracy of the new model of phosphate removal for HD and hemodiafiltration (HDF) treatment. METHODS A total of 109 HD patients from 3 HD centers were enrolled. The actual phosphate removal amount was calculated using the area under the dialysate phosphate concentration time curve. Model modification was executed using second-order multivariable polynomial regression analysis to obtain a new parameter for dialyzer phosphate clearance. Bias, precision, and accuracy were measured in the internal and external validation to determine the performance of the modified model. RESULTS Mean age of the enrolled patients was 63 ± 12 years, and 67 (61.5%) were male. Phosphate removal was 19.06 ± 8.12 mmol and 17.38 ± 6.75 mmol in 4-h HD and HDF treatments, respectively, with no significant difference. The modified phosphate removal model was expressed as Tpo4 = 80.3 × C45 - 0.024 × age + 0.07 × weight + β × clearance - 8.14 (β = 6.231 × 10-3 × clearance - 1.886 × 10-5 × clearance2 - 0.467), where C45 was the phosphate concentration in the spent dialysate measured at the 45th minute of HD and clearance was the phosphate clearance of the dialyzer. Internal validation indicated that the new model was superior to the original model with a significantly smaller bias and higher accuracy. External validation showed that R2, bias, and accuracy were not significantly different than those of internal validation. CONCLUSIONS A new model was generated to quantify phosphate removal by 4-h HD and HDF with a dialyzer surface area of 1.3-1.8 m2. This modified model would contribute to the evaluation of phosphate balance and individualized therapy of hyperphosphatemia.
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The Causes of Hypo- and Hyperphosphatemia in Humans.
Koumakis, E, Cormier, C, Roux, C, Briot, K
Calcified tissue international. 2021;(1):41-73
Abstract
Phosphate homeostasis involves several major organs that are the skeleton, the intestine, the kidney, and parathyroid glands. Major regulators of phosphate homeostasis are parathormone, fibroblast growth factor 23, 1,25-dihydroxyvitamin D, which respond to variations of serum phosphate levels and act to increase or decrease intestinal absorption and renal tubular reabsorption, through the modulation of expression of transcellular transporters at the intestinal and/or renal tubular level. Any acquired or genetic dysfunction in these major organs or regulators may induce hypo- or hyperphosphatemia. The causes of hypo- and hyperphosphatemia are numerous. This review develops the main causes of acquired and genetic hypo- and hyperphosphatemia.
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Role of Phosphate in Biomineralization.
Bhadada, SK, Rao, SD
Calcified tissue international. 2021;(1):32-40
Abstract
Inorganic phosphate is a vital constituent of cells and cell membranes, body fluids, and hard tissues. It is a major intracellular divalent anion, participates in many genetic, energy and intermediary metabolic pathways, and is important for bone health. Although we usually think of phosphate mostly in terms of its level in the serum, it is needed for many biological and structural functions of the body. Availability of adequate calcium and inorganic phosphate in the right proportions at the right place is essential for proper acquisition, biomineralization, and maintenance of mass and strength of the skeleton. The three specialized mineralized tissues, bones, teeth, and ossicles, differ from all other tissues in the human body because of their unique ability to mineralize, and the degree and process of mineralization in these tissues also differ to suit the specific functions: locomotion, chewing, and hearing, respectively. Biomineralization is a dynamic, complex, and lifelong process by which precipitations of inorganic calcium and inorganic phosphate divalent ions form biological hard tissues. Understanding the biomineralization process is important for the management of diseases caused by both defective and abnormal mineralization. Hypophosphatemia results in mineralization defects and osteomalacia, and hyperphosphatemia is implicated in abnormal excess calcification and/or ossification, but the exact mechanisms underlying these processes are not fully understood. In this review, we summarize available evidence on the role of phosphate in biomineralization. Other manuscripts in this issue of the journal deal with other relevant aspects of phosphate homeostasis, phosphate signaling and sensing, and disorders resulting from hypo- and hyperphosphatemic states.
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Effect of Lanthanum Carbonate on Blood Pressure in CKD.
Jamshidian, MS, Larive, B, Gassman, J, Raphael, KL, Chonchol, MB, Ix, JH, Ginsberg, C
American journal of kidney diseases : the official journal of the National Kidney Foundation. 2021;(2):312-314