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Mg P (mg + p)

Distribution by Scientific Domains

Earth and Environmental Science	60%

Selected Abstracts

Effect of Iron(III) Chitosan Intake on the Reduction of Serum Phosphorus in Rats

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2000
JOSEPH BAXTER
Because of the widespread use of aluminium- and calcium-containing phosphate binders for the control of hyperphosphataemia in patients with end-stage renal failure, an iron(III) chitosan complex was synthesised and fed to rats to measure its effect on serum phosphorus and calcium, intestinal phosphate binding and phosphate absorption. Thirty-six Wistar rats were randomly selected and distributed into a baseline group (n = 6), a control group (n = 8 (days 0,15), n = 8 (days 16,30)) and a treatment group (n = 8 (days 0,15), n = 8 (days 16,30)). The control groups ingested AIN-76 diet mix with a 1% w/w fibre content; however, the treatment groups had the fibre content completely substituted with iron(III) chitosan. The mean weights of the treated rats were slightly lower from 15 days (not significant); but overall, rat growth was not stunted in the treatment groups. The serum phosphorus levels of the treated group (n = 8) were significantly reduced after 15 days (P = 0.004; control: 5.7 ± 0.9 mg dL,1; treatment: 4.4±0.5 mg dL,1; 95% CI of difference: 0.5,2.2) and 30 days (P = 0.002; control: 5.5 ± 0.9 mg dL,1; treatment = 4.1 ± 0.6 mg dL,1; 95% CI of difference: 0.6,2.3) as compared with the respective control group. The serum calcium-phosphorus product was 62.0 ± 12.1 mg2 dL,2 for the control and 45.1 ± 6.6 mg2 dL,2 for the treatment group after 30 days (P = 0.004). The serum iron concentration of the treatment group did not differ from the baseline value after 15 and 30 days, but the treatment group was significantly higher than the control group (P < 0.05) after 30 days. The faeces phosphorus levels (mg day,1) were higher (P < 0.01) and its iron content was much higher (P < 0.01) for the treated group. The urine phosphorus (mg kg,1) was not significantly reduced for the treated group, but the mean was consistently less. The kidney and liver weights of both groups were similar, but the phosphorus content of the kidney (mg (g kidney),1) was higher for the treated group after 30 days (P = 0.041; control, 4.2 ± 1.2 mg g,1 vs treatment, 5.6 ± 1.4 mg g,1. Because iron(III) chitosan had a high phosphorus-binding capacity of 308 (mg P) per gram of Fe3+ for both the in-vitro (pH 7.5) and in-vivo studies, which is greater than nearly all commonly used phosphate binders, and a small net phosphorus absorption difference of 3.7 mg day,1, it is an efficient phosphate binder for lowering serum phosphate levels without increasing serum calcium levels. [source]

Uptake of residual phosphate and freshly applied diammonium phosphate by Lolium perenne and Trifolium repens,

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2003
Anne Gallet
Abstract Residual fertilizer phosphorus (residual P) may significantly contribute to crop P nutrition. To test this hypothesis, a pot experiment was conducted with ryegrass (Lolium perenne) and clover (Trifolium repens) grown separately on three different soils which either had not received P fertilizer for at least nine years (0F) or had received P fertilizer equivalent to crop P off-take (F). Soils in the pot experiment were given either none (0F, F) or a single rate of 15 mg P (kg soil),1 as diammonium phosphate (0F+DAP, F+DAP). In the treatments 0F+DAP and F+DAP DAP had been labeled with 33PO4 while in the treatments 0F and F the pool of available soil P had been labeled with carrier-free 33PO4. This allowed estimating the quantities of P in plant dry matter that derived from native soil P, residual fertilizer P or fresh fertilizer P. Fourteen to 62,% of the P in the above ground biomass of white clover or perennial ryegrass were derived from residual P whereas 7 to 28,% were derived from freshly applied DAP. The proportion of P derived from residual P was correlated to the total amount of P fertilizer added to the soils, while the proportion of P derived from DAP was correlated to the concentration of P in the soil solution of the 0F and F soils. Aufnahme von Phosphat aus Rückständen von früherer Düngung und aus frisch ausgebrachtem Diammoniumphosphat durch Lolium perenneund Trifolium repens In Düngerrückständen enthaltener Phosphor (P) kann möglicherweise signifikant zur P-Ernährung von Kulturpflanzen beitragen. Um diese Hypothese zu prüfen, wurde im Topfversuch die P-Aufnahme durch Lolium perenne und Trifolium repens untersucht. Als Substrat dienten drei Böden, die entweder seit mindestens 1989 keine P-Gabe mehr erhalten hatten (0F) oder die jährlich P-Gaben im Umfang der P-Entzüge durch die vorgängigen Kulturen erhalten hatten und deshalb P-Rückstände enthielten (F). Es ergaben sich folgende Verfahren: 0F: ohne P aus Düngerrückständen und frischer Düngung; 0F+DAP: mit P aus frischer Düngung (Diammoniumphosphat, 15 mg P (kg Boden),1); F: mit P aus Düngerrückständen; F+DAP: mit P aus Düngerrückständen und frischer Düngung. In den Verfahren 0F + DAP und F + DAP war DAP mit 33PO4 markiert. In den Verfahren 0F und F war der verfügbare P des Bodens mit carrier-freiem 33PO4 markiert. Dies ermöglichte die Erfassung der Aufnahme von P durch die Pflanzen differenziert nach Herkunft aus Boden, Düngerrückständen und frischem Dünger. Von Düngerrückständen stammten 14,62,%, von frischem Dünger 7,28,% des in den Sprossen der Pflanzen gefundenen P. Der von Düngerrückständen stammende Anteil P in den Pflanzensprossen war korreliert mit dem gesamten Gehalt an P das dem Boden als Dünger zugeführt worden war. Der von frischem DAP stammende Anteil war korreliert mit der P-Konzentration in der Bodenlösung. [source]

Effect of phosphate fertilization on crop yield and soil phosphorus status,

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2003
Anne Gallet
Abstract To evaluate the effect of three phosphorus (P) fertilization regimes (no P, P input equivalent to P off-take by crops, P input higher than P off-take) on crop yield, P uptake, and soil P availability, seven field experiments (six in crop rotations, one under permanent grassland) were conducted in Switzerland during nine years (six trials) or 27 years (one trial). Soil total P (Pt), inorganic P (Pi), organic P (Po), and the amount of isotopically exchangeable soil P were measured in the 0,20,cm and 30,50,cm layers of the arable soils and in the 0,10,cm layer of the permanent grassland soil. Omitting P fertilization resulted in significant yield decreases only in one field crop trial as the amount of P isotopically exchangeable within one minute (E1min) reached values lower than 5 mg P (kg soil),1. In the absence of P fertilization Pi decreased on average from 470 to 410 mg P (kg soil),1 in the upper horizon of 6 sites while Po decreased only at two sites (from 510 to 466 mg P (kg soil),1 on average). In all the treatments of the trials started in 1989 the E1min values of the upper horizon decreased on average from 15.6 to 7.4 mg P (kg soil),1 between 1989 and 1998. These decreases were also observed when P inputs were higher than crops needs, showing that in these soils the highest P inputs were not sufficient to maintain the high initial available P levels. Finally for the six arable trials the values of the isotopic exchange kinetics parameters (R/r1, n, CP) and P exchangeable within 1 minute (E1min) at the end of the experiment could be estimated from the values measured at the beginning of trial and the cumulated P balance. Der Einfluss der Phosphordüngung auf den Pflanzenertrag und den Phosphorstatus des Bodens Die Begrenzung der Düngung mit Phosphat (P) bei Böden, die bereits hohe Gehalte an verfügbarem P aufweisen, kann zur Verringerung der P-Verluste in Oberflächen- und Grundwasser beitragen. Sieben Feldversuche (6 Versuche mit Ackerkulturen, 1 Versuch mit Dauerwiese) wurden während 9 Jahren (6 Versuche) resp. 27 Jahren (1 Versuch) durchgeführt mit dem Ziel, den Einfluss von drei Düngungsraten (keine P-Gabe, P-Gabe entsprechend dem P-Entzug durch die Pflanzen und P-Gabe höher als der P-Entzug durch die Pflanzen) auf Pflanzenertrag, P-Aufnahme und P-Verfügbarkeit zu studieren. Die Gehalte an anorganischem P (Pi) und organischem P (Po), sowie deren Summe (Pt) und die Gehalte an isotopisch austauschbarem P wurden in den Bodentiefen von 0,20,cm und 30,50,cm der ackerbaulichen Versuche und in einer Bodentiefe von 0,10,cm in der Dauerwiese gemessen. Der Verzicht auf P-Düngung führte nur in einem der ackerbaulichen Versuche zu einer signifikanten Abnahme des Pflanzenertrags, wobei der Gehalt an isotopisch austauschbarem P (E1min) unter 5 mg P (kg Boden),1 fiel. Pi sank bei Verzicht auf P-Düngung im oberen Horizont von 6 Böden durchschnittlich von 470 auf 410 mg P (kg Boden),1, während Po nur in 2 Böden absank (durchschnittlich von 510 auf 466 mg P (kg Boden),1). Ueber alle Düngungsverfahren jener Versuche, die 1989 begonnen hatten, sank E1min im oberen Horizont von 1989 bis 1998 durchschnittlich von 15.6 auf 7.4 mg P (kg Boden),1. Die Abnahme wurde auch beobachtet, wenn die P-Gabe höher war als der P-Entzug durch die Pflanzen, was zeigt, dass in diesen Böden selbst die höchste P-Gabe nicht genügte, um den ursprünglich hohen Gehalt an verfügbarem P aufrecht zu erhalten. Schließlich wurden in den 6 ackerbaulichen Versuchen die Parameter der Isotopenaustauschkinetik (R/r1, n, CP) und E1min am Ende des Versuches mit den ursprünglichen Werten zu Beginn des Versuchs verglichen. Es ergaben sich signifikante Beziehungen zwischen den Werten am Ende des Versuchs einerseits und den ursprünglichen Werten und der P-Bilanz andererseits. [source]

In vitro and in vivo estrogenicity and toxicity of o -, m -, and p -dichlorobenzene

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2003
Bram J. Versonnen
Abstract The estrogenicity of o -, m -, and p -dichlorobenzene (DCB) was evaluated with a yeast estrogen screen (YES) and zebrafish (Danio rerio) vitellogenin (VTG) assays. With the YES, p -DCB and m -DCB were found to be estrogenic in a concentration-responsive manner. The relative potency measured with the YES (relative to 17,-estradiol) was 2.2 × 10,7 for p -DCB and 1.04 × 10,8 for m -DCB. Following acute toxicity tests with the zebrafish, plasma VTG production was measured to examine the in vivo estrogenic activity of the three compounds after a 14-d exposure. Adult zebrafish were exposed to different concentrations of o -, m - and p -DCB, ranging from 0.1 to 32 mg/L; ethynylestradiol ([EE2]; 5 ng/L, 10 ng/L, 50 ng/L, and 100 ng/L) was used as a positive control. After exposure, blood samples were taken and protein electrophoresis was performed to determine the relative VTG content. Gonadosomatic indices (GSI) and condition factors (CF) were also calculated. Elevated VTG levels and decreased female GSIs were found in fish exposed to ,5 ng EE2/L and in fish exposed to ,10 mg p -DCB/L. Low GSIs coincided with high levels of VTG in the blood of female zebrafish. This relation was not only found in fish exposed to EE2 but also in controls and fish exposed to DCB. Therefore, a direct or indirect effect of VTG on the GSI is suggested rather than a direct toxic effect of the tested compounds on the gonads. [source]

Effects of glucose and rhizodeposits (with or without cysteine-S) on immobilized- 35S, microbial biomass- 35S and arylsulphatase activity in a calcareous and an acid brown soil

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2004
O. Dedourge
Summary Our aim was to study the effects of C (as glucose and artificial rhizodeposits) on S immobilization, in relation to microbial biomass-S and soil arylsulphatase (ARS) activity, in contrasting soils (a calcareous and an acid brown soil). The glucose-C and artificial rhizodeposit-C with or without cysteine were added at six rates (0, 100, 200, 400, 600 and 800 mg kg,1 soil) to the two soils and then incubated with Na235SO4 for 1 week prior to analysis. The percentages of 35S immobilized increased when C as glucose and rhizodeposit (without cysteine) were added to both soils. With cysteine-containing rhizodeposit, the percentages of 35S immobilized remained relatively stable (23.5% to 29.9%) in the calcareous soil, but decreased in the acid brown soil (52.7% to 31.5%). For both soils, cysteine-containing rhizodeposit additions showed no significant correlation between immobilized- 35S and microbial biomass- 35S, suggesting that microorganisms immobilized cysteine-S preferentially instead of 35S from the tracer (Na235SO4). In the calcareous soil, a positive and significant correlation was found between ARS activity and microbial biomass- 35S (r = 0.85, P < 0.05) when glucose was added. We also saw this correlation in the acid brown soil when rhizodeposit-C without cysteine was added (r = 0.90, P < 0.05). Accordingly, the results showed the presence of extracellular arylsulphatase activity of 48.7 mg p -nitrophenol kg,1 soil hour,1 in the calcareous soil and of 27.0 mg p -nitrophenol kg,1 soil hour,1 in the acid brown soil. [source]