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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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Serum Alkaline Phosphatase, Phosphate, and In-Hospital Mortality in Acute Ischemic Stroke Patients.
Zhong, C, You, S, Chen, J, Zhai, G, Du, H, Luo, Y, Dong, X, Cao, Y, Liu, CF, Zhang, Y
Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2018;(1):257-266
Abstract
BACKGROUND The clinical impacts of serum alkaline phosphatase (ALP) and phosphate on early death are not fully understood in patients with acute ischemic stroke. We examined the associations between serum ALP, phosphate, and in-hospital mortality after ischemic stroke. METHODS Serum ALP and phosphate were measured in 2944 ischemic stroke patients from 22 hospitals in Suzhou City from December 2013 to May 2014. Cox proportional hazard models and restricted cubic splines were used to estimate the relationships between serum ALP and phosphate (both as categorical and continuous variables) and risk of in-hospital mortality. RESULTS During hospitalization, 111 patients (3.7%) died from all causes. After multivariable adjustment, the hazard ratio (HR) of the highest quartile compared with the lowest quartile of ALP was 2.19 (95% confidence interval [CI], 1.20-4.00) for early death. Restricted cubic spline analysis indicated a significant linear association between ALP and death (P-linearity = .017). A U-shaped association of phosphate with in-hospital mortality was observed (P-nonlinearity = .011). Compared with the third quartile of phosphate (1.08-1.21 mmol/L), HRs of the lowest and highest quartiles for early death were 2.17 (1.15-4.08) and 1.70 (.88-3.30), respectively. Sensitivity analyses further confirmed our findings. CONCLUSIONS We observed a graded relationship between serum ALP levels and risk of early death in patients with acute ischemic stroke. There was a U-shaped association between phosphate and all-cause mortality with significantly increased risk among patients with lower phosphate levels.
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3.
Insights into plant phosphate sensing and signaling.
Ham, BK, Chen, J, Yan, Y, Lucas, WJ
Current opinion in biotechnology. 2018;:1-9
Abstract
Phosphorus (P) is a macronutrient essential for plant growth, therefore, soil P level is critical to crop yield potential in agriculture. As Pi levels limit crop yield under many soil conditions, it is crucial to understand the mechanisms by which plants adapt to low-phosphate (Pi) soil conditions and interact with their soil microbiome to improve crop P use efficiency, in order to ensure global food security. Recent advances have been made towards achieving this goal through advancing our understanding of the plant's response to limiting Pi conditions to maintain P homeostasis. In this review, we assess advances made in local and systemic Pi sensing and signaling, and in the molecular events for Pi absorption, redistribution and plant-symbiont interactions. These findings offer important avenues for bio-engineering of agricultural crops with traits for enhanced Pi acquisition and utilization.
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Phosphate removal model: an observational study of low-flux dialyzers in conventional hemodialysis therapy.
Wang, M, Li, H, Liao, H, Yu, Y, You, L, Zhu, J, Huang, B, Yuan, L, Hao, C, Chen, J
Hemodialysis international. International Symposium on Home Hemodialysis. 2012;(3):363-76
Abstract
Precise assessing phosphate removal by hemodialysis (HD) is important to improve phosphate control in patients on maintenance HD. We reported a simple noninvasive model to estimate phosphate removal within a 4-hour HD. One hundred sixty-five patients who underwent HD 4 hours per session using low-flux dialyzers made of polysulfone (1.2 m(2)) or triacetate (1.3 m(2)) were enrolled. Blood flows varied from 180 to 300 mL/min. Effluent dialysate samples were collected during the 4-hour HD treatment to measure the total phosphate removal. Predialysis levels of serum phosphate, potassium, hematocrit, intact parathyroid hormone, total carbon dioxide (TCO(2)), alkaline phosphatase, clinical and dialysis characteristics were obtained. One hundred thirty-five observations were randomly selected for model building and the remaining 30 for model validation. Total amount of phosphate removal within the 4-hour HD was mostly 15-30 mmol. A primary model (model 1) predicting total phosphate removal was Tpo(4) = 79.6 × C(45) (mmol/L) - 0.023 × age (years) + 0.065 × weight (kg) - 0.12 × TCO(2) (mmol/L) + 0.05 × clearance (mL/min) - 3.44, where C(45) was phosphate concentration in spent dialysate measured at the 45 minute of HD and clearance was phosphate clearance of dialyzer in vitro conditions offered by manufacturer's data sheet. Since the parameter TCO(2) needed serum sample for measurement, we further derived a noninvasive model (model 2):Tpo(4) = 80.3 × C(45) - 0.024 × age + 0.07 × weight + 0.06 × clearance - 8.14. Coefficient of determination, root mean square error, and residual plots showed the appropriateness of two models. Model validation further suggested good and similar predictive ability of them. This study derived a noninvasive model to predict phosphate removal. It applies to patients treated by 4-hour HD under similar conditions.
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5.
Kinetic metabolic modelling for the control of plant cells cytoplasmic phosphate.
Cloutier, M, Chen, J, Tatge, F, McMurray-Beaulieu, V, Perrier, M, Jolicoeur, M
Journal of theoretical biology. 2009;(1):118-31
Abstract
A previously developed kinetic metabolic model for plant metabolism was used in a context of identification and control of intracellular phosphate (Pi) dynamics. Experimental data from batch flask cultures of Eschscholtiza californica cells was used to calibrate the model parameters for the slow dynamics (growth, nutrition, anabolic pathways, etc.). Perturbation experiments were performed using a perfusion small-scale bioreactor monitored by in vivo(31)P NMR. Parameter identification for Pi metabolism was done by measuring the cells dynamic response to different inputs for extracellular Pi (two pulse-response experiments and a step-response experiment). The calibrated model can describe Pi translocation between the cellular pools (vacuole and cytoplasm). The effect of intracellular Pi management on ATP/ADP and phosphomonoesters concentrations is also described by the model. The calibrated model is then used to develop a control strategy on the cytoplasmic Pi pool. From the identification of the systems dynamics, a proportional-integral controller was designed and tuned. The closed-loop control was implemented in the small-scale NMR bioreactor and experimental results were in accordance with model predictions. Thus, the calibrated model is able to predict cellular behaviour for phosphate metabolism and it was demonstrated that it is possible to control the intracellular level of cytoplasmic Pi in plant cells.