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Inorganic phosphorus reduces hypercalciuria during total parenteral nutrition by enhancing renal tubular calcium absorption.

BACKGROUND: Increasing the inorganic phosphorus content of total parenteral nutrition (TPN) formulas has been shown to decrease TPN-induced hypercalciuria in experimental animals and humans. The mechanism of this effect, however, has been uncertain. METHODS: By using a randomized cross-over design, seven patients on cyclic TPN were given otherwise identical formulas providing either 15 or 45 mmol/d of inorganic phosphorus. Urinary calcium excretion, serum ultrafilterable calcium, filtered calcium load, fractional calcium excretion, urinary cyclic adenosine 5'-monophosphate (cAMP), and serum levels of ionized calcium, parathyroid hormone (PTH), and vitamin D metabolites were determined at the end of each study period. RESULTS: Urinary calcium excretion was significantly lower when the patients received the higher inorganic phosphorus formula. Increasing the inorganic phosphorus in the TPN formula did not change ultrafilterable calcium or filtered calcium load, but significantly reduced fractional calcium excretion. No differences in serum levels of ionized calcium, PTH, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, or urinary cAMP were observed between treatments. CONCLUSIONS: These results demonstrate that increasing the inorganic phosphorus content of the TPN formula decreases urinary calcium excretion by increasing renal tubular calcium resorption. This effect is not due to alterations in the PTH-1,25-dihydroxyvitamin D axis, but likely reflects a direct action of inorganic phosphorus on the renal tubules.

Absorption↗

Predictors of short-term changes in serum intact parathyroid hormone levels in hemodialysis patients: role of phosphorus, calcium, and gender.

Several factors have been identified as important in the pathogenesis of secondary hyperparathyroidism in end-stage renal disease, including serum calcium, phosphorus, and calcitriol. To examine the independent effects of key factors, we prospectively studied 52 new hemodialysis patients with mild secondary hyperparathyroidism (PTH, 110-670 pg/mL) treated with a standardized regimen of calcium supplements, phosphorus binders, and no vitamin D derivatives. We used simple and multivariable linear regression analysis to examine the relationship between changes in PTH (deltaPTH) levels observed over a 4-week period and various biochemical and demographic variables. By simple linear regression we found that changes in serum phosphorus (r2 = 0.31; beta = 41.6; P = 0.0001), initial phosphorus concentration (r2 = 0.15; beta = 33.4; P = 0.005), initial PTH level (r2 = 0.29; beta = 0.58; P = 0.0001), changes in serum calcium (r2 = 0.12; beta = -74.0; P = 0.01), and gender (r2 = 0.07; beta = 76.1; P = 0.05) were significantly associated with deltaPTH. However, upon multivariable regression analysis, only the changes in phosphorus (partial r2 = 0.31; beta = 37.0; P = 0.0001), initial PTH level (partial r2 = 0.23; beta = 0.50; P = 0.0001), and gender (partial r2 = 0.05; beta = 63.1; P = 0.02) remained significantly associated with deltaPTH. Neither the serum concentration of 1,25-dihydroxyvitamin D3, bicarbonate, aluminum, or albumin nor changes in the serum bicarbonate concentration, the presence of diabetes, KT/V, or age were significantly associated with the deltaPTH. Our findings are consistent with independent effects of phosphorus and gender on parathyroid gland function in patients with dialysis-dependent renal failure through mechanisms that remain to be defined.

Adult↗

Age-dependent decreases of phosphorus and magnesium in human Achilles' tendons.

To elucidate changes of human tendons with aging, the authors studied age-related changes of elements in human Achilles' tendons by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of seven men and seven women, ranging in age from 61 to 97 yr. It was found that the content of calcium increased progressively with aging in the Achilles' tendons, whereas the contents of phosphorus and magnesium decreased gradually with aging. The previous investigations demonstrated that the content of calcium and phosphorus increased progressively with aging in most, but not all, human tissues, except for the bones. In ligaments, such as the anterior cruciate ligament and the ligament of the head of the femur, which are histologically similar to the Achilles' tendon, it was previously found that both the contents of calcium and phosphorus increased with aging in the ligaments. It should be noted that the content of phosphorus in the Achilles' tendons decreased during the aging process. In addition, it was found that there was a very high direct correlation between phosphorus and magnesium contents in the tendons, but not between calcium and phosphorus contents.

Achilles Tendon↗

Synthetic [Asu1,7] eel calcitonin increases phosphorus content in the hepatic mitochondria of rats.

The change of subcellular phosphorus content in the liver was investigated after a single sc administration of synthetic [Asu1,7] eel calcitonin (CT) to fed rats. Administration of CT (80 MRC mU/100 g body weight) produced a significant increase in phosphorus content in the mitochondrial fraction, while this increase was not observed in fractions containing plasma membrane, nuclei, microsomes and cytosol. A significant increase in the mitochondrial phosphorus content was observed even at the lowest dose of CT (40 MRC mU/100 g body weight). A single ip administration of 2,4-dinitrophenol (0.1 mg/100 g body weight), an inhibitor of oxidative phosphorylation, did not prevent significant increases in phosphorus contents of the homogenate and the mitochondria caused by administration of CT (80 MRC mU/100 g body weight), although the drug markedly inhibited ATPase activity in the mitochondria. Administration of CT did not produce a significant alteration in the mictochondrial ATPase activity. These results suggest that phosphorus taken up by the liver cells after CT administration is largely located in the mitochondria, and that this increase is not related to oxidative phosphorylation. Presumably the hepatic mitochondria play a role in the storage of intracellular phosphorus increased by CT.

2,4-Dinitrophenol↗

Calcium, phosphorus, parathyroid hormone, and cardiovascular disease in hemodialysis patients: the USRDS waves 1, 3, and 4 study.

Animal studies suggest that calcium-phosphorus homeostatic abnormalities cause cardiovascular disease in uremia; few observational studies in humans have explored this. Associations in the retrospective United States Renal Data System Waves 1, 3, and 4 Study of 14,829 patients who were on hemodialysis on December 31, 1993, were examined. Mean age and duration of renal replacement therapy were 60.0 and 3.2 yr, respectively; 40.7% had diabetes. Quintiles (Q(1) to Q(5)) of (albumin-adjusted) calcium were </=8.7, 8.8 to 9.2, 9.3 to 9.6, 9.7 to 10.2, and >10.2 mg/dl; phosphorus, </=4.4, 4.5 to 5.3, 5.4 to 6.3, 6.4 to 7.5, and >7.5 mg/dl; calcium-phosphorus product, </=40.9, 41.0 to 50.1, 50.2 to 59.2, 59.3 to 71.0, and >71.0 mg(2)/dl(2); and parathyroid hormone (PTH), </=37, 38 to 99, 100 to 210, 211 to 480, and >480 pg/ml. Higher calcium levels were associated with fatal or nonfatal cardiovascular events (adjusted hazards ratio, 1.08 for Q(5), versus Q(1)) and all-cause mortality (Q(2), 1.07; Q(4), 1.11; Q(5), 1.14). Phosphorus levels were associated with cardiovascular events (Q(2), 1.06; Q(3), 1.13; Q(4), 1.14; Q(5), 1.25) and mortality (Q(4), 1.10; Q(5), 1.19), calcium-phosphorus product was associated with cardiovascular events (Q(3), 1.09; Q(4), 1.14; Q(5), 1.24) and mortality (Q(4), 1.09; Q(5), 1.19), and PTH levels were associated with cardiovascular events (Q(5), 1.12) and mortality (Q(5), 1.17). Despite limitations (including retrospective design; noncurrent study era; and lack of serial calcium, phosphorus, and PTH measurements), this study suggests that disorders of calcium homeostasis are associated with fatal and nonfatal cardiovascular events and all-cause mortality in hemodialysis patients.

Adult↗

Organic phosphorus fractions in organically amended paddy soils in continuously and intermittently flooded conditions.

Soil organic phosphorus (SOP) can greatly contribute to plant-available P and P nutrition. The study was conducted to determine the effects of organic amendments on organic P fractions and microbiological activities in paddy soils. Samples were collected at the Changshu Agro-ecological Experiment Station in Tahu Lake Basin, China, from an experiment that has been performed from 1999 to 2004, on a paddy soil (Gleysols). Treatments consisted of swine manure (SM), wheat straw (WS), swine manure plus wheat straw (SM + WS), and a control (chemical fertilization alone). Organic amendments markedly increased soil total organic phosphorus (TOP) and total organic carbon (TOC), especially in continuously flooded conditions. Based on the fractionation of SOP, organic amendments significantly increased soil labile organic phosphorus (LOP), moderately labile organic phosphorus (MLOP), and moderately stable organic phosphorus (MSOP) compared with the control. For SM and SM + WS treatments, LOP in continuously flooded soils decreased by 30.1 and 36.4%, respectively, compared to intermittently flooded soils. In organically amended soils, continuous flooding showed significantly lower microbial biomass phosphorus (MBP) and alkaline phosphatase activities (APA) than intermittent flooding. In intermittently flooded conditions, incorporating organic amendments into soil resulted in greater P uptake and biomass yield of rice than the control. In the intermittently flooded soils, APA (P < 0.05) and MBP (P < 0.01) were significantly and positively related to TOP, LOP, MLOP, and MSOP, whereas in continuously flooded soils, there was a significant (P < 0.05) negative relationship between MBP, TOP, and MSOP. Based on soil organic P fractions and soil enzymatic and microbiological activities, continuous flooding applied to paddy soils should be avoided, especially when swine manure is incorporated into paddy soil.

Crops, Agricultural↗

Predicting phosphorus availability from soil-applied composted and non-composted cattle feedlot manure.

Prediction of phosphorus (P) availability from soil-applied composts and manure is important for agronomic and environmental reasons. This study utilized chemical properties of eight composted and two non-composted beef cattle (Bos taurus) manures to predict cumulative phosphorus uptake (CPU) during a 363-d controlled environment chamber bioassay. Ten growth cycles of canola (Brassica napus L.) were raised in pots containing 2 kg of a Dark Brown Chernozemic clay loam soil (fine-loamy, mixed, Typic Haploboroll) mixed with 0.04 kg of the amendments. Inorganic P fertilizer (KH2PO4) and an unamended control were included for comparison. All treatments received a nutrient solution containing an adequate supply of all essential nutrients, except P, which was supplied by the amendments. Cumulative P uptake was similar for composted (74 mg kg-1 soil) and non-composted manures (60 mg kg-1 soil) and for the latter and the fertilizer (40 mg kg-1 soil). However, the CPU was significantly higher for organic amendments than the control (24 mg kg-1 soil) and for composted manure than the fertilizer. Apparent phosphorus recovery (APR) from composted manure (24%) was significantly lower than that from non-composted manure (33%), but there was no significant difference in APR between the organic amendments and the fertilizer (27%). Partial least squares (PLS) regression indicated that only two parameters [total water-extractable phosphorus (TPH2O) and total phosphorus (TP) concentration of amendments] were adequate to model amendment-derived cumulative phosphorus uptake (ACPU), explaining 81% of the variation in ACPU. These results suggest that P availability from soil-applied composted and non-composted manures can be adequately predicted from a few simple amendment chemical measurements. Accurate prediction of P availability and plant P recovery may help tailor manure and compost applications to plant needs and minimize the buildup of bioavailable P, which can contribute to eutrophication of sensitive aquatic systems.

Animals↗

Evaluation of sludge reduction and phosphorus recovery efficiencies in a new advanced wastewater treatment system using denitrifying polyphosphate accumulating organisms.

A new biological nutrient removal process, anaerobic-oxic-anoxic (A/O/A) system using denitrifying polyphosphate-accumulating organisms (DNPAOs), was proposed. To attain excess sludge reduction and phosphorus recovery, the A/O/A system equipped with ozonation tank and phosphorus adsorption column was operated for 92 days, and water quality of the effluent, sludge reduction efficiency, and phosphorus recovery efficiency were evaluated. As a result, TOC, T-N and T-P removal efficiency were 85%, 70% and 85%, respectively, throughout the operating period. These slightly lower removal efficiencies than conventional anaerobic-anoxic-oxic (A/A/O) processes were due to the unexpected microbial population in this system where DNPAOs were not the dominant group but normal polyphosphate-accumulating organisms (PAOs) that could not utilize nitrate and nitrite as electron acceptor became dominant. However, it was successfully demonstrated that 34-127% of sludge reduction and around 80% of phosphorus recovery were attained. In conclusion, the A/O/A system equipped with ozonation and phosphorus adsorption systems is useful as a new advanced wastewater treatment plant (WWTP) to resolve the problems of increasing excess sludge and depleted phosphorus.

Adsorption↗

Biological phosphorus removal with nitrite as election acceptor.

Biological phosphorus removal was studied in a sequencing batch reactor (SBR). The results showed that nitrite could be used as electron acceptor in denitrifying phosphorus removal. Feed mode of nitrite had significant influence on denitrifying phosphorus removal. Anoxic phosphorus assimilation rate could reach 10.44 mgP/gSS.h and the percentage of anoxic phosphorus assimilation amount was more than 97% with continuous feed mode. Granular sludge with denitrifying phosphorus removal activity was found in the SBR. The effects of different operational conditions, such as COD loading, settling time, HRT etc., on the formation of granules were also studied.

Biodegradation, Environmental↗

The role of poly-hydroxy-alkanoate form in determining the response of enhanced biological phosphorus removal biomass to volatile fatty acids.

Anaerobic-aerobic batch experiments indicated that poly-hydroxy-alkanoate (PHA) form was important in determining the net phosphorus removal resulting from different volatile fatty acids (VFAs). Poly-3-hydroxy-butyrate (3HB) content was found to correlate fairly well with higher observed aerobic phosphorus uptake per unit PHA carbon degraded. Poly-3-hydroxy-valerate (3HV) correlated with lower aerobic phosphorus uptakes per unit PHA carbon degraded. These experiments, conducted with synthetic wastewater, imply that VFA speciation might have a significant effect on aerobic phosphorus uptakes and net phosphorus removal. In addition, the model parameter fP.UPT (Barker and Dold, 1997) could vary with the proportion of acetic to propionic acid received (i.e., the acetic/propionic acid ratio may be an important parameter for these systems). Carbohydrate data implied that the lower aerobic phosphorus uptake resulting from 3HV might have been caused by a greater fraction of PHA carbon shunting to carbohydrate biosynthesis during aerobiosis.

Acetic Acid↗

Changes in anoxic denitrification rate resulting from prefermentation of a septic, phosphorus-limited wastewater.

A preliminary bench-scale study of parallel University of Cape Town (UCT) biological nutrient removal systems showed improvement in anoxic denitrification rates resulting from prefermentation of a septic (i.e., high volatile fatty acid [VFA] content), phosphorus-limited (i.e., total chemical oxygen demand/total phosphorus [TP] ratio < 40:1) wastewater. Net phosphorus removals due to enhanced biological phosphorus removal (EBPR) were only improved marginally by prefermentation in spite of significant increases in anaerobic phosphorus release, polyhydroxyalkanoate formation, and higher anoxic and aerobic uptakes. This probably was due to the high VFA/TP ratio in the raw influent relative to the VFA requirements for EBPR because enough VFAs were already present for phosphorus removal prior to prefermentation. An additional assessment of prefermentation using parallel UCT systems with step feed of 50% of the influent to the anoxic zone was completed. This second phase quantified the effect of prefermentation in a step-feed scenario, which prioritized prefermentation use to enhance denitrification rather than EBPR. While specific denitrification rates in the anoxic zone were significantly improved by prefermentation, high denitrification in the clarifiers and aerobic zones (simultaneous denitrification) made definitive conclusions concerning the potential improvements in total system nitrogen removal questionable. The prefermented system always showed superior values of the zone settling velocity and sludge volume index and the improvement became increasingly statistically significant when the prefermenter was performing well.

Bacteria, Anaerobic↗

Milk fever in dairy cows. VIII. Effect of injected vitamin D3 and calcium and phosphorus intake on incidence.

In a field trial, effects of prepartal intermuscular injection of 10 million units of vitamin D3 on incidence of milk fever were examined both in relation to intake of calcium and phosphorous during the dry period and previous history of milk fever. Based upon intake of calcium and phosphorus cooperating herds were grouped as feeding: 1) greater than .53% of the total ration dry matter as calcium and greater than .28% as phosphorus: 2) less than .47% as calcium and greater than .28% as phosphorus; 3) greater than .47% to less than .53% as calcium and greater than .22% to less than .28% as phosphorus. Injections of vitamin D3 given approximately 1 wk prepartum reduced incidence of milk fever in cows with previous history of milk fever in all three groups but had no effect in cows with no previous milk fever. Incidence of milk fever was lower in group 3 than for cows of groups 1 and 2 with previous milk fever and than for cows of group 1 with no previous history. The results indicate that careful control of calcium and phosphorus intake during the dry period at .5% calcium and .25% phosphorus of the dry matter of the total ration will limit milk fever incidence to about 10%. Injections of vitamin D3 as described will reduce inicidence of milk fever further in cows with previous milk fever but not in cows with no previous milk fever.

Animals↗

Interrelationship between sodium chloride, sodium bicarbonate, calcium, and phosphorus in laying hen diets.

Three experiments were conducted with Hy-Line W-36 laying hens housed in individual wire cages in open type houses. The first and second experiments were designed to investigate the effects of sodium chloride and sodium bicarbonate fed at two levels of dietary total phosphorus (.30 and .60%). The third experiment was designed to study the interrelationships between age and sodium source. Supplementing sodium chloride at two levels (.37 and 1.11%) did not effect hen performance, except that egg production was better at the lower NaCl. Egg production was greater when .60 rather than .30% dietary phosphorus was fed. Egg specific gravity and egg weight were decreased at the lower dietary phosphorus. The addition of 1.6% sodium bicarbonate in the sodium chloride-free diets was deleterious to hen performance in all experiments. High mortality was observed in both experiments in which hens were fed diets containing high sodium and low chloride. Plasma calcium and phosphorus levels were significantly depressed in hens fed diets containing the lower phosphorus. Blood pH, base excess, bicarbonate, and total carbon dioxide were significantly increased by sodium bicarbonate supplementation, and these values were found to be inversely related to dietary phosphorus levels.

Animals↗

Urolithiasis in pullets and laying hens: role of dietary calcium and phosphorus.

A study was conducted to test the independent and combined effects of high dietary calcium and low available phosphorus on the incidence of urolithiasis in pullets and laying hens. One thousand Single Comb White Leghorn pullets were divided into four diet treatment groups beginning at 50 days of age. A normal calcium (1%), normal available phosphorus (.6%) diet (NCNP) was fed to control pullets. Other pullet groups were fed a high calcium (3.25%), normal available phosphorus (.6%) diet (HCNP), a normal calcium (1%), low available phosphorus (.4%) diet (NCLP), or a high calcium (3.25%), low available phosphorus (.4%) diet (HCLP). At 18 weeks of age, 368 pullets were necropsied. One percent of the HCNP group and 14% of the HCLP group developed urolithiasis. Urolithiasis was not found in pullets raised on the NCNP and NCLP diets. The remaining pullets were transferred to laying cages and were fed a commercial layer ration until they were 51 weeks old. None of the hens raised on the NCNP diet, 12% of the hens raised on the HCNP diet, 2% of the hens raised on the NCLP diet, and 14% of the hens raised on the HCLP diet had urolithiasis. Renal function studies were performed on 18-week-old pullets and 51-week-old hens. Pullets raised on the HCLP diet had significantly higher urine pH, significantly lower fractional inorganic phosphate excretion, and significantly higher fractional calcium excretion when compared with pullets raised on the other diet treatments. The profound effect of the HCLP diet on renal calcium and phosphorus excretion in pullets was not retained in the hens.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

Response of four broiler strains to dietary phosphorus above and below the requirement when brooded at two temperatures.

Four strains of broilers (1,200 birds) were fed diets containing .14, .51, and .88% available phosphorus. The birds were raised for 3 wk at two brooding temperatures, 29.4 C and 35 C, with each being reduced 2.8 degrees per week. Feed consumption, feed conversion, body weight, bone weight (tibia), strength and percentage ash, and mortality were measured in order to assess broiler response. An increase or improvement in each measurement was observed from feeding diets containing .51% rather than .14% available phosphorus, but no further increase or improvement was observed in measurements by feeding diets containing .88% rather than .51% available phosphorus. The values for feed consumption, weight gain, and bone weight were significantly lower at the higher temperatures than at the lower temperatures. There were interactions of broiler strain-by-phosphorus with feed consumption, BW gain, and bone weight and strength; also, of temperature-by-phosphorus with bone strength, bone ash, and mortality. These interactions indicate that the bird's response to phosphorus is influenced by strain and environmental temperature.

Analysis of Variance↗

Differential effects of very high doses of doxercalciferol and paricalcitol on serum phosphorus in hemodialysis patients.

BACKGROUND: Treatment of secondary hyperparathyroidism (SHPT) includes use of calcitriol (1,25D(3)) to suppress parathyroid hormone (PTH), but dosing of 1,25D(3) is limited by the development of hypercalcemia and a high calcium x phosphorus (Ca x P) product due to gut absorption of calcium and phosphorus as well as enhanced bone resorption. The vitamin D analog 19-Nor-1,25(OH)2-vitamin D2 (paricalcitol) and the prohormone 1alpha-OH-vitamin D2 (doxercalciferol) have been proposed as alternatives which may cause less hypercalcemia and elevated Ca x P, while still suppressing PTH. METHODS: We performed a prospective study to assess the acute bone mobilization effects of very high doses of paricalcitol and doxercalciferol. 13 hemodialysis patients received 160 mcg of paricalcitol and 120 mcg of doxercalciferol on 2 separate occasions in a research center while on a low calcium, low phosphorus diet, and sevelamer alone as a phosphorus binder. Changes in Ca, PO4, and PTH were measured over 36 h. RESULTS: Serum phosphorus rose faster, and peaked significantly higher at 36 h following doxercalciferol (2.12 +/- 0.11 mmol/l) than paricalcitol (1.85 +/- 0.07 mmol/l; p = 0.025). Ca x P product also rose more following doxercalciferol than paricalcitol, and peaked higher at 36 h (5.02 +/- 0.26 vs. 4.54 +/- 0.21 mmol/l; p = 0.061). In contrast, suppression of PTH at 36 h was comparable (63% after paricalcitol and 65% with doxercalciferol). CONCLUSION: Consistent with animal studies, paricalcitol provides profound PTH suppression, while stimulating bone resorption and/or intestinal absorption less than doxercalciferol, resulting in less elevation of serum phosphorus and Ca x P.

Adult↗

[Intracellular phosphorus pool in a culture of the cyanobacterium Spirulina platensis].

An intracellular phosphorus pool in a monoculture of the cyanobacterium Spirulina platensis was assessed using radioactive and nonradioactive phosphorus. The derived dependence of specific growth rate on the intracellular content of mineral phosphorus can be presented in the form of the Droop equation. It was found that the stage of replenishment of the intracellular phosphorus pool may affect the phosphorus turnover estimation in aquatic environments from the results of short-term measurements of phosphorus uptake.

Biomass↗

[Phosphorus as a limiting nutrient in drinking water biological treatment].

Bacterial Growth Potential (BGP) method was used to investigate the limiting effect of phosphorus in the biological process for drinking water treatment in a water plant in Huai River basin. BGP was increased by 54% when 50 micrograms.L-1 KH2PO4-P was added to the raw water, while addition of other inorganic nutrients had no significant difference from the addition of phosphorus. The effect of addition of 20 mg.L-1 C6H12O6 to raw water was not so strong as that of 50 micrograms.L-1 KH2PO4-P. The CODMn removal rate of the biological filter was 7.5 percentiles higher than the control one and carbon was the main limiting nutrient in its effluent when phosphorus was added to the raw water, while phosphorus was the main limiting nutrient in the effluent of the control filter. These results suggest that phosphorus was a limiting nutrient and had a stronger limiting effect than carbon on the biological process in this plant thus the removal efficiency of the organic matters could be increased by adding phosphorus to the influent.

Bacteria↗