Overexpression of a Eutrema salsugineum phosphate transporter gene EsPHT1;4 enhances tolerance to low phosphorus stress in soybean

OBJECTIVE

To enhance Pi absorption and utilization efficiency of soybean, a member of PHT1 gene family was isolated and characterized from E. salsugineum, which was a homologous gene of AtPHT1;4 and consequently designated as EsPHT1;4.

RESULTS

Quantitative real-time PCR (qRT-PCR) analysis showed that the transcript level of EsPHT1;4 significantly increased both in roots and leaves of E. salsugineum under Pi deficient conditions. Furthermore, EsPHT1;4 was transferred to soybean cultivar "YD22" using an Agrobacterium-mediated cotyledonary-node transformation method. Overexpression of EsPHT1;4 in soybean not only promoted the increase of plant biomass and yield of transgenic plants upon low P stress, but also increased the accumulation and transportation of Pi from roots to leaves in the transgenic soybean lines.

CONCLUSION

EsPHT1;4 was critical for controlling the accumulation and translocation of Pi in plants, and can be subsequently used as an effective foreign gene for the improvement of P use efficiency of crops by genetic manipulation.

Decision support system for NPK fertilization: a solution method for minimizing the impact on human health, climate change, ecosystem quality and resources

Sugarcane cultivation requires correct fertilizer rates. However, when nutrients are not available, or there is over-fertilization, the yields are significantly reduced and the environmental burden increase. In this study, it is proposed a decision support system (DSS) for the correct NPK (nitrogen, phosphorus and potassium) fertilization. The DSS consists of two fuzzy models; the edaphic condition model (EDC-M) and the NPK fertilization model (NPK-M). The DSS using parameters from soil analysis and is based on the experience of two groups of experts to avoid the bias to the reality of a single group of professionals. The results of the DSS are compared with the results of soil analysis and those of the group of experts. One hundred and sixty tests were developed in the NPK-M. The N rate shows R ²=0.981 for the DSS and R ²=0.963 for soil analyzes. The P rate shows R ²=0.9702 for the DSS and R ²=0.9183 for the soil analyzes. The K rate shows R ²=0.9691 for the DSS and R ²=0.9663 for the soil analyzes. Environmental results indicate that the estimated rates with the DSS do reduce the environmental impact on the tests performed.

Phosphorus enriched effluents increase eutrophication risks for mangrove systems in northeastern Brazil

Discharge of effluents loaded with phosphorus (P) from anthropogenic activities constitutes serious eutrophication risks in marine and terrestrial ecosystems, including mangroves. Three mangroves in NE-Brazil were studied to evaluate the impact of P-rich-effluents from shrimp farming and domestic sewage, in relation to a control area (natural mangrove). Soil phosphorus fractionation and water chemical analysis were performed to assess potential pollution. We observed the most labile P forms increased gradually and significantly from control to sewage to shrimp farm impacted mangroves as observed by increasingly dissolved orthophosphate (PO₄^3-) content in water and the exchangeable/soluble P (Exch-P) extracted from soils, which is supported by the discriminant analysis. Exch-P results were correlated to Humic-Acid-P, which can release more labile P forms when mineralized. Our results demonstrate a substantial impact of aquiculture and sewage effluents in mangroves at both organic and inorganic P fractions, raising important concerns regarding pollution for these marine ecosystems.

Effects of an invasive polychaete on benthic phosphorus cycling at sea basin scale: An ecosystem disservice

Macrofaunal activities in sediments modify nutrient fluxes in different ways including the expression of species-specific functional traits and density-dependent population processes. The invasive polychaete genus Marenzelleria was first observed in the Baltic Sea in the 1980s. It has caused changes in benthic processes and affected the functioning of ecosystem services such as nutrient regulation. The large-scale effects of these changes are not known. We estimated the current Marenzelleria spp. wet weight biomass in the Baltic Sea to be 60-87 kton (95% confidence interval). We assessed the potential impact of Marenzelleria spp. on phosphorus cycling using a spatially explicit model, comparing estimates of expected sediment to water phosphorus fluxes from a biophysical model to ecologically relevant experimental measurements of benthic phosphorus flux. The estimated yearly net increases (95% CI) in phosphorous flux due to Marenzelleria spp. were 4.2-6.1 kton based on the biophysical model and 6.3-9.1 kton based on experimental data. The current biomass densities of Marenzelleria spp. in the Baltic Sea enhance the phosphorus fluxes from sediment to water on a sea basin scale. Although high densities of Marenzelleria spp. can increase phosphorus retention locally, such biomass densities are uncommon. Thus, the major effect of Marenzelleria seems to be a large-scale net decrease in the self-cleaning capacity of the Baltic Sea that counteracts human efforts to mitigate eutrophication in the region.

Cyanobacterial Toxins of the Laurentian Great Lakes, Their Toxicological Effects, and Numerical Limits in Drinking Water

Cyanobacteria are ubiquitous phototrophic bacteria that inhabit diverse environments across the planet. Seasonally, they dominate many eutrophic lakes impacted by excess nitrogen (N) and phosphorus (P) forming dense accumulations of biomass known as cyanobacterial harmful algal blooms or cyanoHABs. Their dominance in eutrophic lakes is attributed to a variety of unique adaptations including N and P concentrating mechanisms, N₂ fixation, colony formation that inhibits predation, vertical movement via gas vesicles, and the production of toxic or otherwise bioactive molecules. While some of these molecules have been explored for their medicinal benefits, others are potent toxins harmful to humans, animals, and other wildlife known as cyanotoxins. In humans these cyanotoxins affect various tissues, including the liver, central and peripheral nervous system, kidneys, and reproductive organs among others. They induce acute effects at low doses in the parts-per-billion range and some are tumor promoters linked to chronic diseases such as liver and colorectal cancer. The occurrence of cyanoHABs and cyanotoxins in lakes presents challenges for maintaining safe recreational aquatic environments and the production of potable drinking water. CyanoHABs are a growing problem in the North American (Laurentian) Great Lakes basin. This review summarizes information on the occurrence of cyanoHABs in the Great Lakes, toxicological effects of cyanotoxins, and appropriate numerical limits on cyanotoxins in finished drinking water.

Serum phosphorus is related to left ventricular remodeling independent of renal function in hospitalized patients with chronic kidney disease

BACKGROUND

Increasing evidence indicated that phosphorus emerged as an important cardiovascular risk factor in patients with chronic kidney disease (CKD). The fact that serum phosphorus was closely linked to vascular and valvar calcification may account for one important reason. However, left ventricular remodeling may also serve as another potential mechanism of the cardiac toxicity of phosphorus. In the present study, we evaluated the association of serum phosphorus with left ventricular remodeling.

METHODS

We investigated consecutive hospitalized patients with pre-dialysis CKD, who did not have symptomatic heart failure or take any phosphorus binder or calcitriol medications. Transthoracic echocardiography was applied to assess their left ventricular remodeling indices, both structural and functional.

RESULTS

The 296 study subjects (mean age 56.4years) included 169 (57.1%) men, 203 (68.6%) hypertensive patients. In addition to gender, systolic blood pressure, and estimated glomerular filtration rate, serum phosphorus was an independent determinant of left ventricular mass index (LVMI, P=0.001). Similarly, serum phosphorus was also a determinant of left ventricular end diastolic dimension (P=0.0003), but not of relative wall thickness. In multivariate logistic analyses, serum phosphorus was significantly and independently associated with the prevalence of left ventricular hypertrophy (LVH, odds ratio [OR] 2.38 for each 1mmol/L increase, 95% CI 1.20-4.75, P=0.01). Moreover, the association was only confirmatory in eccentric LVH (OR 3.01, 95% CI 1.43-6.32, P=0.003) but not in concentric LVH (1.38, 95% CI, 0.54-3.49, P=0.50).

CONCLUSION

Serum phosphorus was significantly and independently associated with LVMI and the prevalence of eccentric LVH in hospitalized patients with CKD.

Lamin A is involved in the development of vascular calcification induced by chronic kidney failure and phosphorus load

Vascular calcification remains one of the main factors associated to morbidity and mortality in both ageing and chronic kidney disease. Both hyperphosphataemia, a well-known promoter of vascular calcification, and abnormal processing defects of lamin A/C have been associated to ageing. The main aim of this study was to analyse the effect of phosphorus load in the differential expression pattern of genes and proteins, particularly of lamin A/C, which are involved in phenotypic change of the vascular smooth muscle cells to osteoblast-like cells. The in vivo study of the calcified abdominal aortas from nephrectomized rats receiving a high phosphorus diet showed among others, a repression of muscle related proteins and overexpression of lamin A/C. Similar results were observed in vitro, where primary vascular smooth muscle cells cultured in calcifying medium showed increased expression of prelamin A and lamin A and abnormalities in the nuclear morphology. Co-immunoprecipitation assays showed novel and important physical interactions between lamin A and RUNX2 during the process of calcification. In fact, the knockdown of prelamin A and lamin A inhibited the increase of Runx2, osteocalcin and osteopontin gene expression, calcium deposition, nuclear abnormalities and the RUNX2 protein translocation into the nucleus of the cell. These in vivo and in vitro results highlight the important role played by lamin A in the process of vascular calcification.

Between the utility and hazards of phosphorus through the centuries

Phosphorus has been shown to be a predictor of cardiovascular mortality in kidney disease subjects. Phosphorus was discovered in 1669 and was considered a philosophers stone, it was used as medicament but there were reported deaths after its use. High serum levels of phosphorus are associated with increased risk for cardiovascular disease in the general population in subjects free from chronic kidney disease. Phosphorus can be defined as a useful and hazardous element for public health.

Soil phosphorus constrains biodiversity across European grasslands

Nutrient pollution presents a serious threat to biodiversity conservation. In terrestrial ecosystems, the deleterious effects of nitrogen pollution are increasingly understood and several mitigating environmental policies have been developed. Compared to nitrogen, the effects of increased phosphorus have received far less attention, although some studies have indicated that phosphorus pollution may be detrimental for biodiversity as well. On the basis of a dataset covering 501 grassland plots throughout Europe, we demonstrate that, independent of the level of atmospheric nitrogen deposition and soil acidity, plant species richness was consistently negatively related to soil phosphorus. We also identified thresholds in soil phosphorus above which biodiversity appears to remain at a constant low level. Our results indicate that nutrient management policies biased toward reducing nitrogen pollution will fail to preserve biodiversity. As soil phosphorus is known to be extremely persistent and we found no evidence for a critical threshold below which no environmental harm is expected, we suggest that agro-environmental schemes should include grasslands that are permanently free from phosphorus fertilization.

[The clinical and X-ray classification of osteonecrosis of the low jaw]

OBJECTIVE

To elaborate a clinical and X-ray classification of osteonecrosis of the low jaw in people with desomorphine or pervitin addiction.

MATERIAL AND METHODS

Ninety-two patients with drug addiction who had undergone orthopantomography, direct frontal X-ray of the skull, and multislice computed tomography, followed by multiplanar and three-dimensional imaging reconstruction were examined. One hundred thirty four X-ray films and 74 computed tomographic images were analyzed.

RESULTS

The authors proposed a clinical and X-ray classification of osteonecrosis of the low jaw in people with desomorphine or pervitin addiction and elaborated recommendations for surgical interventions on the basis of the developed classification.

CONCLUSION

The developed clinical and X-ray classification and recommendations for surgical interventions may be used to treat osteonecroses of various etiology.

[Information about phosphorus additives and nutritional counseling]

Hyperphosphatemia is a common disorder in patients with chronic kidney disease (CKD) , and may result in hyperparathyroidism and renal osteodystrophy. Hyperphosphatemia also may contribute to deterioration vascular calcification and increase mortality. Hence, correction and prevention of hyperphosphatemia is a main component of the management of CKD. This goal is usually approached both by administering phosphorus binders and by restricting dietary phosphorus (P) intake. Dietary intake of phosphorus (P) is derived largely from foods with high protein content or food additives and is an important determinant of P balance in patient with CKD. Food additives (PO4) can dramatically increase the amount of P consumed in the daily diet, especially because P is more readily absorbed in its inorganic form. In addition, information about the P content and type in prepared foods is often unavailable or misleading. Therefore, during dietary counseling of patients with CKD, we recommended that they consider both the absolute dietary P content and the P-to-protein ratio of foods and meals including food additives.

Effect of phosphogypsum amendment on soil physico-chemical properties, microbial load and enzyme activities

Phosphogypsum (PG) is produced as a solid waste from phosphatic fertilizer plants. The waste slurry is disposed off in settling ponds or in heaps. This solid waste is now increasingly being used as a calcium supplement in agriculture. This study reports the effectof PG amendmenton soil physico chemical properties, bacterial and fungal count and activities of soil enzymes such as invertase, cellulase and amylase over an incubation period of 28 days. The highest mean percent carbon loss (55.98%) was recorded in 15% PG amended soil followed by (55.28%) in 10% PG amended soil and the minimum (1.68%) in control soil. The highest number of bacterial colonies (47.4 CFU g(-1) soil), fungal count (17.8 CFU g(-1) soil), highest amylase activity (38.4 microg g(-1) soil hr(-1)) and cellulase activity (38.37 microg g(-1) soil hr(-1)) were recorded in 10% amended soil. Statistically significant difference (p<0.05) has been recorded in the activities of amylase and cellulase over the period of incubation irrespective of amendments. Considering the bacterial and fungal growth and the activities of the three soil enzymes in the control and amended sets, it appears that 10% PG amendment is optimal for microbial growth and soil enzyme activities.

Hyperphosphatemia in Renal Failure

The recent recognition that hyperphosphatemia is a strong predictor of survival on dialysis has rekindled interest in the regulation and control of serum phosphate. In incipient renal failure hyperphosphatemia is prevented by increased fractional renal phosphate excretion mediated via an increase in parathyroid hormone and the novel phosphaturic hormone FGF-23 (and possibly others). At a glomerular filtration rate of approximately 30 ml/min this compensatory mechanism fails and hyperphosphatemia ensues. Pre-dialytic serum phosphate concentrations of >6 mg/dl increase cardiac mortality presumably to a large extent, but not exclusively, via promoting vascular calcification. It has recently been recognized that vascular calcification is not only a passive precipitation process following transgression of the critical Ca-x-P product, but is an active process accompanied by expression of osteoblastic bone markers in the vessel wall. Because of the recent recognition of the relation between vascular calcification and serum phosphate as well as serum calcium, there is a need for novel calcium-free phosphate binders. Currently sevelamer and lanthanum carbonate have been introduced and trivalent iron preparations are under development.

High phosphorus diet induces vascular calcification, a related decrease in bone mass and changes in the aortic gene expression

In chronic kidney disease, hyperphosphatemia has been associated to vascular calcifications. Moreover, the rate and progression of vascular calcification have been related with the reduction of bone mass and osteoporotic fractures, hereby suggesting a strong link between vascular calcification and bone loss. Our aim was to prospectively study the effects of high phosphorus diet on bone mass, vascular calcification and gene expression profile of the arterial wall. A rat model of 7/8 nephrectomy fed with normal (0.6%) and moderately high (0.9%) phosphorus diet was used. Biochemical parameters, bone mineral density and vascular calcifications were assessed. A microarray analysis of the aortic tissue was also performed to investigate the gene expression profile. After 20 weeks, the rats fed with a high phosphorus diet showed a significant increase in serum phosphorus, PTH, and creatinine, together with aortic calcification and a decrease in bone mass. The histological analysis of the vascular calcifications showed areas with calcified tissue and the gene expression profile of this calcified tissue showed repression of muscle-related genes and overexpression of bone-related genes, among them, the secreted frizzled related proteins, well-known inhibitors of the Wnt pathway, involved in bone formation. The study demonstrated prospectively the inverse and direct relationship between vascular calcification and bone mass. In addition, the microarrays findings provide new information on the molecular mechanisms that may link this relationship.

The contribution of marsh zones to water quality in Dutch shallow lakes: a modeling study

Many lakes have experienced a transition from a clear into a turbid state without macrophyte growth due to eutrophication. There are several measures by which nitrogen (N) and phosphorus (P) concentrations in the surface water can be reduced. We used the shallow lake model PCLake to evaluate the effects of three measures (reducing external nutrient loading, increasing relative marsh area, and increasing exchange rate between open water and marsh) on water quality improvement. Furthermore, the contribution of different retention processes was calculated. Settling and burial contributed more to nutrient retention than denitrification. The model runs for a typical shallow lake in The Netherlands showed that after increasing relative marsh area to 50%, total phosphorous (TP) concentration in the surface water was lower than the Maximum Admissible Risk (MAR, a Dutch government water quality standard) level, in contrast to total nitrogen (TN) concentration. The MAR levels could also be achieved by reducing N and P load. However, reduction of nutrient concentrations to MAR levels did not result in a clear lake state with submerged vegetation. Only a combination of a more drastic reduction of the present nutrient loading, in combination with a relatively large marsh cover (approximately 50%) would lead to such a clear state. We therefore concluded that littoral marsh areas can make a small but significant contribution to lake recovery.

[Rescue and treatment for the mass burn casualties of yellow phosphorus explosion]

OBJECTIVE

To summarize the characteristics and treatment of burn casualties of yellow phosphorus explosion, so as to share the experiences in emergency treatment.

METHODS

By analyzing the data related to this accident, the characteristics of the injury and experiences of treatment for mass burn casualties from yellow phosphorous explosion were summarized.

RESULTS

Eighty-one patients, 72 males and 9 females, were injured in a yellow phosphorus explosion. The mean age of the patients was 24 +/- 13 years old (5-42 y). The mean total burn surface area was (9 +/- 11)% [(0.4% - 70.0%))] TBSA, and the mean burn surface area of III degrees/IV degrees was (7 +/- 10)% [(0.4% - 60.0%)] TBSA. Most of the patients showed the symptoms and signs of phosphorus poisoning. Among all the patients, 27 cases (33.3%) showed hepatic dysfunction, 15 cases (18.5%) had renal dysfunction, 42cases (51.9%) showed electrolytes disorders. Among the 8 patients with burn surface area over 10% TBSA and less than 20% TBSA, high levels of cardiac enzymes were found in 6 cases, anaemia in 7 cases (3 with progressive anaemia), asphyxia occurred in 1 case 48 hours after burn, and in 1 case complicated with stress ulcer. Escharectomy and skin grafting were performed within four days after burn in 72 patients. All the patients survived, some of them showed impaired hand function and hypertrophic scar, and partial finger amputation was done in 3 patients.

CONCLUSION

Yellow phosphorus explosion produces deep burn injuries in surrounding people especially in exposed parts such as head, hand and so on. Adequate organization of medical resources for emergency treatment, early debridement, and accelerating excretion of phosphorus are the key points for the successful rescue of mass casualties.

Osteonecrosis of the jaw and bisphosphonates: a comparison with white phosphorus, radium, and osteopetrosis

INTRODUCTION

Recent reports of bisphosphonate-associated jaw osteonecrosis are reminiscent of earlier incidents in which a comparable syndrome was caused by occupational exposure to white phosphorus or radium. Osteonecrosis of the jaw is also caused by an inherited disease: osteopetrosis. This review analyzes the biomedical and social aspects of these four situations associated with jaw osteonecrosis.

RESULTS

Clinical evidence is contradictory but suggests aminobisphosphonates cause rare cases of jaw necrosis. In addition to jaw problems, generalized skeletal defects characterize osteopetrosis and exposure to phosphorus or radium and there is evidence of decreased bone resorption in these conditions and with bisphosphonate therapy.

CONCLUSION

Bisphosphonate-induced jaw necrosis appears to be an on-target toxicity as the same mechanism, inhibition bone resorption, probably underlies both the therapeutic and adverse effects. Since bisphosphonates are retained for long periods by bone the theoretical potential for skeletal toxicity is increased by using higher doses of potent aminobisphosphonates administered less frequently.

Hypophosphatemia associated with paraproteinemia: a case report and review of the literature

The differential diagnosis for hypophosphatemia is long, and involves complex, overlapping physiological systems. Practitioners are often guilty, however, of simply supplementing phosphate without fully investigating the etiology of the problem. The purpose of this case presentation is to illustrate a case of spurious hypophosphatemia that initially led to unnecessary phosphate replacement in a woman with undiagnosed multiple myeloma. An 85-year-old African American woman was admitted to the hospital for congestive heart failure exacerbation. The patient was incidentally found to be profoundly hypophosphatemic and was also diagnosed with multiple myeloma at this hospitalization. Normal phosphorus levels were difficult to maintain despite aggressive replacement. A serum sample initially reported to have an abnormally low phosphorus concentration on the Beckman CX7 analyzer was reanalyzed with the Kodak Ektachem 700 system, revealing the phosphorus concentration to be towards the higher limit of the normal range on the same sample. We conclude that clinicians should proceed with caution before aggressively treating abnormal phosphorus levels in patients with known paraproteinemia. Conversely, unexplained phosphorus abnormalities should bring disorders associated with paraproteinemia, such as multiple myeloma, into the differential diagnosis. Knowledge of how various phosphorus assays are affected by paraproteins is essential to guiding diagnosis and treatment. We also review mechanisms of reported interference with common assays.

Phosphorus-containing food additives and the accuracy of nutrient databases: implications for renal patients

OBJECTIVE

Phosphorus-containing additives are increasingly being added to food products. We sought to determine the potential impact of these additives. We focused on chicken products as an example.

METHODS

We purchased a variety of chicken products, prepared them according to package directions, and performed laboratory analyses to determine their actual phosphorus content. We used ESHA Food Processor SQL Software (version 9.8, ESHA Research, Salem, OR) to determine the expected phosphorus content of each product.

RESULTS

Of 38 chicken products, 35 (92%) had phosphorus-containing additives listed among their ingredients. For every category of chicken products containing additives, the actual phosphorus content was greater than the content expected from nutrient database. For example, actual phosphorus content exceeded expected phosphorus content by an average of 84 mg/100 g for breaded breast strips. There was also a great deal of variation within each category. For example, the difference between actual and expected phosphorus content ranged from 59-165 mg/100 g for breast patties. Two 100-g servings of additive-containing products contained, on average, 440 mg of phosphorus, or about half the total daily recommended intake for dialysis patients.

CONCLUSIONS

Phosphorus-containing additives significantly increase the amount of phosphorus in chicken products. Available nutrient databases do not reflect this higher phosphorus content, and the variation between similar products makes it impossible for patients and dietitians to accurately estimate phosphorus content. We recommend that dialysis patients limit their intake of additive-containing products, and that the phosphorus content of food products be included on nutrition facts labels.

Potassium and phosphorus repletion in hospitalized patients: implications for clinical practice and the potential use of healthcare information technology to improve prescribing and patient safety

OBJECTIVES

Evaluate potassium and phosphorus repletion in hospitalized patients. Assess the potential role for use of various methods, including healthcare information technology, to improve prescribing and patient safety.

RESEARCH DESIGN AND METHODS

Inpatient medication profiles were screened to identify orders for potassium and phosphorus replacement products. Electronic laboratory and medical records were used to evaluate efficacy and safety. Eligibility for oral therapy was defined by the presence of other scheduled oral medications on the medication profile. Appropriateness of prescribing was based on adherence to the hospital guidelines for repletion.

RESULTS

Overall, 134 orders for potassium in 92 patients and 36 orders for phosphorus in 27 patients were evaluated over a 3-week data collection period. Intravenous (IV) potassium was prescribed in 73% of replacement episodes (46% as single doses and 54% within large volume IV fluids), with 85% for normokalemia or mild-to-moderate cases of hypokalemia. Phosphorus orders involved single doses of IV potassium phosphate (mean 13.1 mmol) in 75% of cases. Approximately 85% of doses were for mild or moderate hypophosphatemia. Eligibility for oral therapy was evident in 74% of normokalemic or mild hypokalemic cases receiving IV potassium products and in 33% of cases receiving IV phosphorus replacement. Six cases of mild hyperkalemia were observed. No hyperphosphatemia was documented. Study limitations include use of a retrospective design, inability to discern whether some electrolyte doses were given with a preventative intent, potential overestimation of the number of patients eligible for oral repletion, and lack of data on the accessibility of the laboratory serum concentrations or the awareness of serum values to the prescribers.

CONCLUSIONS

Intravenous potassium and phosphate products are commonly prescribed for mild or moderate cases of hypokalemia or hypophosphatemia. Many patients met eligibility for oral therapy. Efforts to enhance prescriber education and implement computerized prescribing and decision support systems have the potential to improve prescribing and reduce possibilities of adverse drug events and medication errors related to potassium and phosphate administration.

Too much of a good thing: on stoichiometrically balanced diets and maximal growth

Nutritional imbalances are of great interest in the ecological stoichiometry literature, in which researchers have focused almost exclusively on cases where nutrients are available in low amounts relative to energy (carbon), and animal growth is impaired due to insufficient nutrient intake. Little attention has been given to situations where food elemental content is higher than the level that satisfies animal requirements. However, most animals are strongly homeostatic with respect to the elemental composition of their body; hence they must excrete the excess of elements that are not in short supply. To date, stoichiometric theory has assumed that excretion of superfluous elements does not come with a cost and, thus, that consumption of food with surplus nutrients does not impair performance. Here we challenge this assumption, based on a compilation of several examples involving food phosphorus content that show that the performance of a wide variety of animals decreases when supplied with food containing high concentrations of (potentially) limiting nutrients. We discuss possible mechanisms for this phenomenon, and suggest that animals most vulnerable to effects of high food nutrient content are those that normally feed on low- quality (low-nutrient: C) food, and have a relatively low body nutrient content themselves, such as herbivores and detritivores.

Dairy products, calcium and phosphorus intake, and the risk of prostate cancer: results of the French prospective SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydants) study

Although dairy products have been found to be associated with an elevated risk of prostate cancer, studies investigating the potential effect of Ca are limited, and findings are inconsistent. The objective of the present study was to test the relationship between the risk of prostate cancer and consumption of dairy products and Ca. The analysis included 2776 men from the French SU.VI.MAX (Supplementation en Vitamines et Minéraux Antioxydants) prospective study, among whom sixty-nine developed prostate cancer during the follow-up period (median: 7.7 years). Food consumption was assessed at inclusion from repeated 24 h records and nutrient intake was calculated using a food composition table. A higher risk of prostate cancer was observed among subjects with higher dairy product (relative risk (RR; 95 % CI), 4th quartile v. 1st: 1.35 (1.02, 1.78), P = 0.04) and Ca intake (RR (95 % CI), 4th quartile v. 1st: 2.43 (1.05, 5.62), P = 0.04). Nevertheless, we identified a harmful effect of yoghurt consumption upon the risk of prostate cancer (RR (95 % CI), increment 125 g/d: 1.61 (1.07, 2.43), P = 0.02) independently of the Ca content. Our data support the hypothesis that dairy products have a harmful effect with respect to the risk of prostate cancer, largely related to Ca content. The higher risk of prostate cancer with linear increasing yoghurt consumption seems to be independent of Ca and may be related to some other component.

Impact of Convective Flow on Phosphorus Removal in Maintenance Hemodialysis Patients

OBJECTIVE

Hyperphosphatemia leads to increased risk of death in maintenance hemodialysis patients (MHD). This study investigated phosphorus (P) removal, P reduction rate (PRR), and P rebound, comparing on-line, high-volume hemodiafiltration in postdilution (HDF) and high-flux hemodialysis (HD) in a setting of an equal amount of produced dialysate solution in both modalities.

METHODS

A total of 22 MHD patients, treated with regular 3 x 4 hours HDF weekly, were randomly dialyzed with one 4-hour session of HDF and of HD. In both modalities, an equal amount of produced dialysate solution of 800 mL/minute was used. The only variable was the fact that in HDF, 100 mL/min of this produced dialysate solution was used as replacement fluid. The other parameters were kept identical: blood flow rate, 350 mL/min; high-flux polysulfone F80 dialyzer; and 4800 E monitor, (Fresenius, Bad Homburg, Germany). The P removal was measured in total spent dialysate and ultrafiltrate volumes. Statistical analyses were done with the paired t-test.

RESULTS

The mean total P removed with HDF was 1159 +/- 296 mg, and 972 +/- 312 mg with HD (P < .001), ie, 19% higher in HDF; PRR was significantly higher in HDF (63.3%) versus HD (58.6%) (P = .014). The mean serum P did not differ: 5.3 mg/dL in HDF and 5.2 mg/dL in HD. There was a linear correlation between serum P and P removal. With a serum P level up to 5 to 5.5 mg/dL, HDF achieved a higher P removal compared with HD. The difference gradually decreased as the serum P value increased. Above 7 mg/dL, no difference in total P removal was observed. There was a high but equal rebound percentage at 60 minutes in HDF (42%) and HD (39%) (P = .42). With HDF, no predialysis metabolic acidosis was noted.

CONCLUSIONS

Treatment with on-line HDF in postdilution resulted in a higher P removal and higher PRR compared with HD. The long-term implementation of this modality may result in a more optimal serum P control, without an increase in the number of or lengthening of the dialysis sessions.

Relation of calcium-phosphorus product to the severity of aortic stenosis in patients with normal renal function

Calcium-phosphorus product (CaxP) has been associated with severity of aortic stenosis (AS) in dialysis patients, but it is unknown whether a relation exists in patients with normal renal function. One hundred seven patients with AS and normal serum creatinine were studied to determine whether there was an association between CaxP and AS severity, and it was found that CaxP was inversely related to AS severity, as measured by aortic valve area and transvalvular gradients.

[Calcification of heart valves in hemodialized patients and their cardiosurgical correction]

Development of vascular and systemic calcification is one of the more serious and often occurring complications in hemodialyzed patients. The cardiac valves calcifications are of the essential importance. They are result of the very complicated calcification process connected with hyperphosphataemia, hyperparathyroidism, calcium carbonate administering and active vitamin D3 metabolites as well as using dialysis fluids with high concentration of calcium. Elevated P and Ca x P product are both significant predictors of cardiovascular mortality in hemodialized patients. We describe two patients with cardiac failure because of cardiac valves calcification. Both patients underwent artificial valves implantation. The patients showed a marked improvement of the quality of life and haemodynamic status.

Phosphorus in runoff assessed by anion exchange resin extraction and an algal assay

Eutrophication of surface waters can be accelerated by agricultural inputs of phosphorus (P), provided that P is in a form that can be utilized by aquatic algae. We studied anion exchange resin (AER) extraction and a dual culture algal assay (DCAA) for the determination of potentially algal-available P in water samples without sediment preconcentration. Our material consisted of agricultural and forest runoff and wastewaters. The results obtained by the two methods were essentially equal when the samples contained only small amounts of particulate phosphorus (PP) in relation to dissolved molybdate-reactive phosphorus (DRP). However, in turbid agricultural runoff, P extracted with AER averaged 72% (n = 17) of the P yield of the 3-wk DCAA (R2 = 0.94). When the runoff samples were diluted for the AER extraction in the same manner as for the DCAA, the AER-P yield increased to 85% (n = 5) of DCAA-P. The minimum detectable value was greater for the AER test (41 microg L(-1) AER-extractable P) than for the DCAA (7 microg L(-1) DCAA-P). At concentrations greater than about 50 microg L(-1) AER-P or DCAA-P, the accuracy of the methods was satisfactory, with the coefficient of variation in replicated analyses being less than 10% for the AER test and less than 20% for the DCAA. Other anions competing for the exchange sites of the AER decreased P recovery by 15 to 20% when their equivalent concentration exceeded about 4 mmol, L(-1), and this effect was relatively constant over a large concentration range. We consider that AER extraction is a suitable low-cost method to estimate the algal availability of P in runoff samples.

Consequences of livestock grazing on water quality and Benthic algal biomass in a Canadian natural grassland plateau

The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau, Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early season livestock grazing (June-August), (2) late season livestock grazing (August-September), (3) all season grazing (June-September), and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation, and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments. Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons) were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable, and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO(2)(-) + NO(3) (-) and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal communities were either nitrogen-limited or not limited by nutrients, depending on stream and season.

Phosphorus in rivers--ecology and management

This paper examines the nature of the risk to riverine ecosystems from artificially enhanced loads of phosphorus, considers the key sources of phosphorus enrichment and ways of controlling them, and provides a framework for developing control strategies. The aquatic plant community is the foundation for a healthy and diverse riverine ecosystem, providing food, shelter and breeding habitats for a wide range of animal species. Phosphorus enrichment in rivers can degrade the plant community by altering the competitive balance between different aquatic plant species, including both higher plants and algae. This has consequences for the whole ecosystem. To promote healthy riverine plant communities and the wide range of animal species dependent on them, phosphorus concentrations need to be reduced to as near to background levels as possible. The risk of adverse effects declines as phosphorus concentrations approach background levels, such that any incremental reduction should be seen as a positive step towards trophic restoration. Pragmatic management targets vary between 0.02 and 0.1 mg(-1) soluble reactive phosphorus, depending on river type, with an interim target of 0.2 mg(-1) for heavily enriched rivers. Continuous point sources of phosphorus, dominated by sewage treatment works, have a highly important influence on levels of bioavailable phosphorus in the water column through the growing season. It is important to tackle point sources comprehensively so that reductions in phosphorus concentrations are maximised during this critical time of year. Diffuse sources of phosphorus, particularly from agriculture, are a major contributor to phosphorus levels in riverine sediments, where it can be utilised by benthic algae and rooted plants. This phosphorus can also be released into the water column by a variety of processes. As point sources are brought under control, the relative contribution from diffuse sources becomes increasingly important. An integrated programme of control, involving proactive action on both point and diffuse sources, will be required in most circumstances to bring phosphorus levels in the water column and sediment down to near background levels.

Acute management of white phosphorus burn

White phosphorus is a combustible solid that is used in many of the smoke devices that are prevalent throughout the military arsenal. Exposure to phosphorus-containing compounds causes serious, often fatal, burns and can be the source of significant morbidity and lengthy hospital stays. I present the case of an individual with serious cutaneous phosphorus burns suffered at a munitions manufacturing plant. The purpose of this paper is to discuss the emergent treatments necessary in such patients and to discuss decontamination in the phosphorus-burned patient. Phosphorus-containing munitions are prevalent throughout the military arsenal, and all military physicians should be aware of these treatments.

Effect of different operational parameters in the enhanced biological phosphorus removal process. Experimental design and results

The uncontrolled dumping of phosphorus into a water environment creates serious problems of eutrophication, affecting water quality and causing grave problems in the aquatic ecosystem. European legislation demands drastic reduction of phosphorus dissolved in wastewater. Enhanced Biological Phosphorus Removal (EBPR) is the current tendency in wastewater treatment. This biological process depends on a multiplicity of variables, but its three main factors are: influent COD/P ratio, anaerobic fraction and sludge retention time (SRT). The aim of this work is to statistically determine the effect of these three parameters in EBPR through a response surface methodology. The objective function that has been chosen is phosphorus removed per unit biomass formed. This function provides ample information on BPR, since the quantity of phosphorus removed depends on the accumulative capacity of the microorganisms present. Two levels were chosen for the SRT (5 and 10 days), two for the anaerobic fraction (0.1 and 0.2), and six for levels of the influent COD/P ratio (between 16 and 87). The experiments were undertaken at pilot scale (100 litres) with an A2/O configuration, with simultaneous nitrogen and phosphorous removaL The wastewater used is a synthetic mixture of complex sources of carbon and nitrogenwithout volatile fatty acids. The empirical model obtained indicates that the factor most influencing the EBPR process is the influent COD/P ratio, whilst the anaerobic fraction is that which has least influence. Additionally, there is an optimum in the influent COD/P ratio that is to be found between 41 and 48.

Effect of nutrients supplementation on anaerobic sludge development and activity for treating distillery effluent

Startup of laboratory anaerobic reactors and treatment efficiency were investigated by supplementing the distillery effluent feed with macronutrients (Ca, P) and micronutrients (Ni, Fe and Co) under mesophilic conditions. Calcium and phosphate were deterimental to the treatment efficiency and sludge granulation. Traces of salts of iron, nickel and cobalt, individually and in combinations improved the COD removal efficiency and sludge granulation process.

The management of white phosphorus burns

Phosphorus burns are a rarely encountered chemical burn, typically occurring in battle, industrial accidents, or from fireworks. Death may result even with minimal burn areas. Early recognition of affected areas and adequate resuscitation is crucial. Amongst our 2765 admissions between 1984 and 1998, 326 patients had chemical burns. Seven admissions were the result of phosphorus burns. Our treatment protocol comprises 1% copper sulfate solution for neutralization and identification of phosphorus particles, copious normal saline irrigation, keeping wounds moist with saline-soaked thick pads even during transportation, prompt debridement of affected areas, porcine skin coverage or skin grafts for acute wound management, as well as intensive monitoring of electrolytes and cardiac function in our burns center. Intravenous calcium gluconate is mandatory for correction of hypocalcemia. Of the seven, one patient died from inhalation injury and the others were scheduled for sequential surgical procedures for functional and cosmetic recovery. Cooling affected areas with tap water or normal saline, prompt removal of phosphorus particles with mechanical debridement, intensive monitoring, and maintenance of electrolyte balance are critical steps in initial management. Fluid resuscitation can be adjusted according to urine output. Early excision and skin autografts summarize our phosphorus burn treatment protocol.

Annual nutrients export modelling by analysis of landuse and topographic information: case of a small Mediterranean catchment

The preservation of water bodies from eutrophication implies accurate estimation of phosphorus and nitrogen loads and the control of nutrient production on a catchment scale. In this paper, a simple tool for the modelling of annual nutrient loads is presented. It is implemented in ARC/INFO GIS using Arc Macro Language (AML). The use of a GIS is justified as the spatial characteristics of the catchment area (land use, industrial wastewater location) dictate water quality. The annual nutrient loads are worked out on the catchment scale, using existing GIS routines together with specific routines developed in AML for hydrological and water quality modelling purposes. The catchment area is divided into hydrological subcatchments with relatively homogeneous spatial characteristics. Each subcatchment is linked to a specific nutrient export potential. These nutrient loads, calculated on a subcatchment-by-subcatchment basis, are conveyed to the outlet of the catchment and allow annual nutrient load estimation. A comparison with a water monitoring study is conducted to verify the adequation of modelling results for phosphorus and nitrogen loads.

Characterization of drinking water treatment residuals for use as a soil substitute

The beneficial use of drinking water treatment residuals (WTRs) as a potential source of topsoil for land reclamation was evaluated. Seventeen WTRs were characterized for use as soil substitutes by comparing chemical and physical properties and plant nutrients of the WTRs with soil. A tomato (Lycopersicon esculentum) bioassay was performed to determine the ability of soil chemical tests to measure WTR phosphorus (P) adequacy. The WTR chemical and physical properties were typically adequate for crop growth. None of the WTRs were considered unsuitable as soil substitutes based on plant nutrients, with the exception of P. Tomato vegetative yield and tissue P were poor either because of phytotoxic nitrite-nitrogen (NO2-N) (> 10 mg/kg) generated during the bioassay or because of WTR P deficiency. Limited data suggest that WTRs with NO2-N less than 10 mg/kg and Olsen P greater than 50 mg/kg, water soluble P greater than 580 micrograms/L, or Mehlich III P greater than 54 mg/kg support growth but still produce inadequate tissue P in tomatoes.

Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet

BACKGROUND

Ascorbic acid has a pronounced enhancing effect on the absorption of dietary nonheme iron when assessed by feeding single meals to fasting subjects. This contrasts with the negligible effect on iron balance of long-term supplementation with vitamin C.

OBJECTIVE

Our goal was to examine the effect of vitamin C on nonheme-iron absorption from a complete diet rather than from single meals.

DESIGN

Iron absorption from a complete diet was measured during 3 separate dietary periods in 12 subjects by having the subjects ingest a labeled wheat roll with every meal for 5 d. The diet was freely chosen for the first dietary period and was then altered to maximally decrease or increase the dietary intake of vitamin C during the second and third periods.

RESULTS

There was no significant difference in mean iron absorption among the 3 dietary periods despite a range of mean daily intakes of dietary vitamin C of 51-247 mg/d. When absorption values were adjusted for differences in iron status and the 3 absorption periods were pooled, multiple regression analysis indicated that iron absorption correlated negatively with dietary phosphate (P = 0.0005) and positively with ascorbic acid (P = 0.0069) and animal tissue (P = 0.0285).

CONCLUSIONS

The facilitating effect of vitamin C on iron absorption from a complete diet is far less pronounced than that from single meals. These findings may explain why several prior studies did not show a significant effect on iron status of prolonged supplementation with vitamin C.

Cultural eutrophication control through water reuse

The increasing use of mineral fertilisers over the last decades has contributed to the appearance of numerous cases of water eutrophication, a new form of water pollution. The starting point of eutrophication is the increase of nutrient concentration (nitrogen and phosphorus) in a water mass, which is subsequently followed by an uncontrolled growth of primary producers and episodes of oxygen depletion due to microbial decomposition of algal organic matter. The excess nutrient loads reaching surface waters are usually associated to discharges from anthropogenic activities, which normally involve direct water usage instead of reuse of reclaimed effluents. Agriculture activities and livestock breeding are two of the main nutrient sources responsible for water eutrophication, as well as human--urban and industrial--wastewater discharges. Wastewater reclamation and reuse can be a suitable strategy for preserving the quality of natural waters, by suppressing effluent discharges and the associated nutrient contributions to receiving waters. Reuse of reclaimed water for agricultural and landscape irrigation as well as for environmental enhancement offers an adequate strategy for preserving natural water systems from eutrophication.

Environmental impacts of phosphogypsum vs. borrow pits in roadfill construction

A comparison was performed of the environmental impacts of using phosphogypsum versus conventional fill materials (e.g., from borrow pits) for road construction. The study compared a hypothetical roadway with an actual roadway in Florida; the two facilities differed only in that phosphogypsum was employed as fill material instead of conventional materials. The effect of the two construction approaches on the plant and animal communities was considered, as was the impact on the surface and ground water. A summary was made of the comparative impacts, and a comparison matrix was constructed using integral numbers to depict impacts ranging from -5 (most impact) to 0 (none) to + 5, showing most benefit of the part of the project on a given resource. Values were subjective, based upon investigators' experience. Four categories (plant and animal communities, water quality, water resources, and air quality) were considered. The cumulative total was +12 for phosphogypsum and -6 for conventional fill material.