BIOTECHNOLOGY JOURNAL, Issue 9 2009
Dimitris Platis
Abstract Aqueous two-phase partition systems (ATPS) have been widely used for the separation of a large variety of biomolecules. In the present report, the application of a polyethylene glycol/phosphate (PEG/phosphate) ATPS for the separation of anti-HIV monoclonal antibodies 2G12 (mAb 2G12) and 4E10 (mAb 4E10) from unclarified transgenic tobacco crude extract was investigated. Optimal conditions that favor opposite phase partitioning of plant debris/mAb as well as high recovery and purification were found to be 13.1% w/w (PEG 1500), 12.5% w/w (phosphate) at pH 5 with a phase ratio of 1.3 and 8.25% w/w unclarified tobacco extract load. Under these conditions, mAb 2G12 and mAb 4E10 were partitioned at the bottom phosphate phase with 85 and 84% yield and 2.4- and 2.1-fold purification, respectively. The proposed ATPS was successfully integrated in an affinity-based purification protocol, using Protein A, yielding antibodies of high purity and yield. In this study, ATPS was shown to be suitable for initial protein recovery and partial purification of mAb from unclarified transgenic tobacco crude extract. [source]

ACIDIFIED SODIUM CHLORITE, TRISODIUM PHOSPHATE AND POPULATIONS OF SALMONELLA TYPHIMURIUM AND STAPHYLOCOCCUS AUREUS ON CHICKEN-BREAST SKIN

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2006
HAYDAR ÖZDEM
ABSTRACT The present study was designed to determine the individual and combined effects of acidified sodium chlorite (ASC) and trisodium phosphate (TSP) antimicrobial treatments. Chicken-skin samples inoculated with Salmonella typhimurium and Staphylococcus aureus were separately dipped into sterile tap water, 10% TSP, 0.1% ASC, 0.1% ASC followed by 10% TSP and 10% TSP followed by 0.1% ASC for 15 s at 25C ± 1. On day 0, reductions were 1.4,1.6 log for S. Typhimurium and 1.1,2.1 log for S. aureus, while they were 1.8,2.9 and 0.7,1.7 log, respectively, on day 5 of storage. Results indicated that treatment with ASC solution alone was more effective than treatment with ASC and TSP solutions combined in reducing S. aureus populations on chicken skin during the entire storage period. Similarly, treatment with TSP solution alone was more effective than treatment with ASC and TSP solutions combined in reducing S. typhimurium populations on chicken skin on days 1, 3 and 5 of storage. [source]

PULSES OF PHOSPHATE PROMOTE DOMINANCE OF THE TOXIC CYANOPHYTE CYLINDROSPERMOPSIS RACIBORSKII IN A SUBTROPICAL WATER RESERVOIR,

JOURNAL OF PHYCOLOGY, Issue 3 2009
Amanda J. Posselt
The role of dissolved inorganic phosphorus (DIP) in promoting dominance of the toxic nitrogen (N)-fixing cyanobacterium Cylindrospermopsis raciborskii (Wo,osz.) Seenayya et Subba Raju was examined in a subtropical water reservoir, Lake Samsonvale (=North Pine reservoir). A novel in situ bioassay approach, using dialysis tubing rather than bottles or bags, was used to determine the change in C. raciborskii dominance with daily additions of DIP. A statistically significant increase in dominance of C. raciborskii was observed when DIP was added at two concentrations (0.32 ,M and 16 ,M) in a daily pulse over a 4 d period in three separate experiments in the summer of 2006/2007. There was an increase in both C. raciborskii cell concentrations and biovolume in two DIP treatments, but not in the ammoniacal N + DIP treatment. In addition, overall phytoplankton cell concentrations increased with DIP addition, indicating that Lake Samsonvale was DIP limited at the time of experiments. Given the bioassay response, it is likely that dominance of C. raciborskii could increase in Lake Samsonvale with periodic injections of DIP such as inflow events. [source]

EFFECTS OF NITRATE AND PHOSPHATE DISCHARGE FROM A FERTILIZER PRODUCTION PLANT IN A FJORD

JOURNAL OF PHYCOLOGY, Issue 2001
Article first published online: 24 SEP 200
Pedersen, A.1,2, Knutzen, J.2, Walday, M.2, Molvær, M.2 & Johnsen, T.2 1Department of Ecology and Evolutionary Biology, University of Connecticut at Stamford, Stamford, CT. 06901 U.S.A;. 2Norwegian Institute for Water Research, P.O.B. 173 Kjelsås, 0411 Oslo, Norway. "Hydro Agri Glomfjord" a fertilizer producer has been discharging large quantities of ammonium, nitrate and phosphate into Glomfjord (in northern Norway, N 66,48°, E 13,57°) since 1947. The effects of the nutrient load to the Fjord have resulted in classical eutrophication symptoms. Elevated nutrient levels have resulted in frequent plankton blooms and seasonally reduced O2 levels in the deep-water bodies as well as an eradication of the normal littoral assemblages. The fucoid belt had been replaced by various green algae 6 km from the outlet and outward the fjord. The effect is only seen on the northern side of the Fjord. After some improvement in the discharge loads in the 1980's, the condition in the pelagic column improved with regard to plankton blooms and deep water O2 concentration. The littoral communities didn't, show any indication of recovery and a pollution indication index based on algal composition, showed even increased eutrophication. [source]

Effect of Enzyme and Cofactor Immobilization on the Response of Ethanol Oxidation in Zirconium Phosphate Modified Biosensors

ELECTROANALYSIS, Issue 10 2010
Mitk'El
Abstract Two different self-contained ethanol amperometric biosensors incorporating layered [Ru(phend)2bpy]2+ -intercalated zirconium phosphate (ZrP) as the mediator as well as yeast -alcohol dehydrogenase (y- ADH) and its cofactor nicotinamide adenine dinucleotide (NAD+) were constructed to improve upon a design previously reported where only this mediator was immobilized in the surface of a modified electrode. In the first biosensor, a [Ru(phend)2bpy]2+ -intercalated ZrP modified carbon paste electrode (CPE) was improved by immobilizing in its surface both y- ADH and NAD+ using quaternized Nafion membrane. In the second biosensor, a glassy carbon electrode was modified with [Ru(phend)2bpy]2+ -intercalated ZrP, y- ADH, and NAD+ using Nafion as the holding matrix. Calibration plots for ethanol sensing were constructed in the presence and absence of ZrP. In the absence of ZrP in the surface of the modified glassy carbon electrode, leaching of ADH was observed as detected by UV-vis spectrophotometry. Ethanol sensing was also tested in the presence and absence of ascorbate to measure the selectivity of the sensor for ethanol. These two ethanol biosensors were compared to a previously reported one where the y -ADH and the NAD+ were in solution, not immobilized. [source]

Platform for Highly Sensitive Alkaline Phosphatase-Based Immunosensors Using 1-Naphthyl Phosphate and an Avidin-Modified Indium Tin Oxide Electrode

ELECTROANALYSIS, Issue 19 2009
Abdul Aziz
Abstract We report a versatile platform for highly sensitive alkaline phosphatase (ALP)-based electrochemical biosensors that uses an avidin-modified indium tin oxide (ITO) electrode as a sensing electrode and 1-naphthyl phosphate (NPP) as an ALP substrate. Almost no electrocatalytic activity of NPP and good electrocatalytic activity of 1-naphthol (ALP product) on the ITO electrodes allow a high signal-to-background ratio. The effective surface covering of avidin on the ITO electrodes allows very low levels of nonspecific binding of proteins to the sensing electrodes. The platform technology is used to detect mouse IgG with a detection limit of 1.0,pg/mL. [source]

Phosphate regulates uranium(VI) toxicity to Lemna gibba L. G3

ENVIRONMENTAL TOXICOLOGY, Issue 1 2007
Martin Mkandawire
Abstract The influence of phosphate on the toxicity of uranium to Lemna gibba G3 was tested in semicontinuous culture with synthetic mine water developed as an analogue of surface water of two abandoned uranium mining and ore processing sites in Saxony, Germany. Six concentrations of uranium were investigated under five different supply regimes of PO43, at constant pH (7.0 ± 0.5) and alkalinity (7.0 ± 1.6 mg L,1 total CO32,). The results showed significant inhibition of specific growth rates in cultures exposed to the highest uranium concentrations (3500 and 7000 ,g U L,1) at lowest PO43, supply of 0.01 mg L,1. An increase of phosphate concentration from 0.01 to 8.0 mg L,1 resulted in an increase of EC50 from 0.9 ± 0.2 to 7.4 ± 1.9 mg L,1 (significant with Student's t test, P > 0.05). The accumulation of uranium in L. gibba increased exponentially with the increase in uranium concentration in cultures with 0.01 and 0.14 mg PO43, L,1. Accumulation also increased significantly when PO43, supply was increased from 0.14 to 1.36 mg PO43, L,1 for all uranium concentrations. However, as the supply of PO43, gradually increased from 1.36 to 8.0 mg PO43, L,1, uranium bioaccumulation increased slightly but insignificantly before leveling off. Uranium speciation modeling with PhreeqC geochemical code predicted increases in the proportions of uranyl phosphate species when PO43, concentrations increase in the media. Most of these uranyl phosphate species have a high probability of precipitation [saturation indices (SI) > 0.93]. Therefore, the alleviation of uranium toxicity to L. gibba with phosphates is due to interactions among components of the media, mainly uranyl and phosphate which results in precipitation. Consequently, bioavailable fractions of uranium to L. gibba are reduced. This might explain lack of consistent EC50 values for uranium to most aquatic organisms. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 9,16, 2007. [source]

Responses of biofilms to combined nutrient and metal exposure

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002
Núria Ivorra
Abstract Numerous studies have reported marked sensitivities of diatom species to phosphate and organic pollution but have ignored interactions with other common contaminants. The aim of the present study was to investigate the single and joint effects of increased phosphate and metal (cadmium, zinc) concentrations on benthic diatom communities. Microalgal biofilms from a relatively unpolluted stream were exposed in the laboratory to Zn, Cd, and P, separately and in combination, in concentrations found at a polluted stream in the same catchment. The Zn concentration reduced algal growth in biofilms more than the Cd concentration. Phosphate compensated for the single effect of each metal but not for their combined effects. Diatom community changes were evaluated using water quality indices based on the empirical sensitivities of taxa to nutrients (TDI) and organic pollution (%PTV). Phosphate exposure resulted in an increase of the eutrophy rank and presumed pollution-tolerant taxa. In contrast, exposure to Zn, Zn + Cd, and Zn + Cd + P caused a marked reduction of the TDI and %PTV community values. The successional trends in the laboratory matched the observed differences in microphyte communities in the reference and polluted river stations. However, the autoecology of the species present also revealed that the resulting composition of diatom communities cannot be attributed solely to the direct toxic effects of metal and nutrients and their interaction. Observed changes in the relative abundance of species are also determined by their growth form and microdistribution in biofilms. [source]

Formation of Metastable Na2CrO4 -Type LiNiPO4 from a Phosphate,Formate Precursor

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2010
Violeta Koleva
Abstract High-pressure modification of LiNiPO4 with a Na2CrO4 -type structure was obtained at ambient pressure and low temperature from a mixed LiNi,phosphate,formate precursor, LiNiPO4Hx(HCOO)x·yH2O (where x , 1.2 and y , 2.5). The structural and thermal characterization of the precursor and the LiNiPO4 compositions were carried out by powder XRD analysis, IR spectroscopy, and DSC analysis. Thermal treatment of LiNiPO4Hx(HCOO)x·yH2O precursors between 450 and 650 °C yields a mixture of the two structural modifications of LiNiPO4: the Na2CrO4 type and the olivine type. It was established that the obtained Na2CrO4 -type LiNiPO4 is a metastable phase, which completely transforms at 700 °C into the olivine-type phase. The enthalpy of the phase transition is ,H = ,43.40 kJ,mol,1. The mechanism of formation of the two forms of LiNiPO4 from the LiNi,phosphate,formate precursor is discussed. [source]

Phase Relations Between ,-Tricalcium Phosphate and Hydroxyapatite with Manganese(II): Structural and Spectroscopic Properties

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2006
Isaac Mayer
Abstract The preparation of Mn-containing ,-tricalcium phosphate (,-TCP) samples was achieved in two ways: a) transformation of precipitated Mn-containing calcium hydroxyapatite (HA) to ,-TCP by heating at 1100 °C, and b) preparation by solid-state reaction of a mixture of CaCO3, (NH4)2HPO4, and Mn(NO3)2 at 1100 °C. Powder X-ray diffraction (XRD) analyses of the samples, obtained by both methods, show well-defined patterns with structural data of the rhombohedral R3c, ,-TCP phase. The calculated lattice constants are smaller than those known for ,-Ca3(PO4)2 because of substitution of Ca2+ by Mn2+. EPR spectroscopy indeed reveals that manganese is divalent in the samples. Apparently, the Ca(5) site in the ,-TCP structure is occupied by Mn2+. The distribution of Mn2+ between the ,-TCP and the HA phase in the case of preparation (b) was studied by EPR spectroscopy, and a pronounced preference for the former lattice was found. Micron- and submicron-sized crystals with visible faces were observed by TEM in the case of ,-TCP prepared by solid-state reaction, and large micron-sized, droplike-shaped crystals, sensitive to beam radiation, were found in the case of samples prepared by heating HA at elevated temperatures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Intercalates of Vanadyl Phosphate with Benzonitrile and Tolunitrile

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2003
Ludvík Bene
Abstract Intercalates of vanadyl phosphate with benzonitrile and p -tolunitrile were prepared and characterized by X-ray powder diffraction, TG analysis, IR and Raman spectroscopy. Both intercalates contain one nitrile molecule per formula unit. The intercalates prepared are moisture sensitive and guest molecules are easily replaced by water molecules. The nitrile molecules are anchored to the host layers by an N,V donor-acceptor bond. Local structures and interactions appearing in the intercalates were suggested on the base of quantum chemical calculations. These calculations support the results of the IR and Raman spectroscopy, indicating the formation of a C,N,V bond in the intercalates. The calculated basal spacings (11.32 Å for the benzonitrile and 13.00 Å for the tolunitrile intercalates) are in good agreement with the experimental values (11.22 and 13.19 Å, respectively). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Physical and Biological Properties of a Novel Hydrogel Composite Based on Oxidized Alginate, Gelatin and Tricalcium Phosphate for Bone Tissue Engineering,

ADVANCED ENGINEERING MATERIALS, Issue 12 2007
K. Cai
A novel hydrogel composite is reported in this study, which was derived from oxidized alginate, gelatin and tricalcium phosphate (TCP). The physical and biological properties of these hydrogel composites prepared with oxidized sodium alginate with different oxidation degrees were investigated. The drug delivery potential of this hydrogel composite as a carrier was evaluated by using Vitamin B2 as a model drug as well. An in vitro investigation with encapsulation of osteoblast revealed that these composites were biocompatible. This hydrogel composite presented here may be utilized for the fabrication of potential injectable systems for tissue engineering, drug delivery and other medical applications. [source]

The phosphate site of trehalose phosphorylase from Schizophyllum commune probed by site-directed mutagenesis and chemical rescue studies

FEBS JOURNAL, Issue 5 2008
Christiane Goedl
Schizophyllum commune,,,-trehalose phosphorylase utilizes a glycosyltransferase-like catalytic mechanism to convert its disaccharide substrate into ,- d -glucose 1-phosphate and ,- d -glucose. Recruitment of phosphate by the free enzyme induces ,,,-trehalose binding recognition and promotes the catalytic steps. Like the structurally related glycogen phosphorylase and other retaining glycosyltransferases of fold family GT-B, the trehalose phosphorylase contains an Arg507-XXXX-Lys512 consensus motif (where X is any amino acid) comprising key residues of its putative phosphate-binding sub-site. Loss of wild-type catalytic efficiency for reaction with phosphate (kcat/Km = 21 000 m,1·s,1) was dramatic (,107 -fold) in purified Arg507,Ala (R507A) and Lys512,Ala (K512A) enzymes, reflecting a corresponding change of comparable magnitude in kcat (Arg507) and Km (Lys512). External amine and guanidine derivatives selectively enhanced the activity of the K512A mutant and the R507A mutant respectively. Analysis of the pH dependence of chemical rescue of the K512A mutant by propargylamine suggested that unprotonated amine in combination with H2PO4,, the protonic form of phosphate presumably utilized in enzymatic catalysis, caused restoration of activity. Transition state-like inhibition of the wild-type enzyme A by vanadate in combination with ,,,-trehalose (Ki = 0.4 ,m) was completely disrupted in the R507A mutant but only weakened in the K512A mutant (Ki = 300 ,m). Phosphate (50 mm) enhanced the basal hydrolase activity of the K512A mutant toward ,,,-trehalose by 60% but caused its total suppression in wild-type and R507A enzymes. The results portray differential roles for the side chains of Lys512 and Arg507 in trehalose phosphorylase catalysis, reactant state binding of phosphate and selective stabilization of the transition state respectively. [source]

Comment on "Aliovalent Substitutions in Olivine Lithium Iron Phosphate and Impact on Structure and Properties"

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2010
Brian L. Ellis
No abstract is available for this article. [source]

Reply to Comment on "Aliovalent Substitutions in Olivine Lithium Iron Phosphate and Impact on Structure and Properties"

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2010
Yet-Ming Chiang
No abstract is available for this article. [source]

Aliovalent Doping for Improved Battery Performance: Aliovalent Substitutions in Olivine Lithium Iron Phosphate and Impact on Structure and Properties (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
Mater.
Lithium metal phosphate olivines have emerged as important storage electrodes in batteries for electric vehicles and other applications addressing global issues of energy supply and climate change. On page 1060, Meethong et al. use controlled aliovalent solute doping to tailor the defect and atomic structure in olivines, and demonstrate the resulting impact on physical and electrochemical properties. [source]

Aliovalent Substitutions in Olivine Lithium Iron Phosphate and Impact on Structure and Properties

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
Nonglak Meethong
Abstract Lithium transition metal phosphate olivines are enabling a new generation of high power, thermally stable, long-life rechargeable lithium batteries that may prove instrumental in the worldwide effort to develop cleaner and more sustainable energy. Nanoscale (<100,nm) derivatives of the olivine family LiMPO4 (M,=,Fe, Mn, Co, Ni) are being adopted in applications ranging in size scale from hybrid and plug-in hybrid electric vehicles to utilities-scale power regulation. Following the previous paradigm set with intercalation oxides, most studies have focused on the pure ordered compounds and isovalent substitutions. In contrast, even the possibility for, and role of, aliovalent doping has been widely debated. Here, critical tests of plausible defect compensation mechanisms using compositions designed to accommodate Mg2+, Al3+, Zr4+, Nb5+ ions on the M1,and/or M2 sites of LiFePO4 with appropriate charge-compensating defects are carried out, and conclusive crystallographic evidence for lattice doping, e.g., up to at least 12 atomic percent added Zr, is obtained. Structural and electrochemical analyses show that doping can reduce the lithium miscibility gap, increase phase transformation kinetics during cycling, and expand Li diffusion channels in the structure. Aliovalent modifications may be effective for introducing controlled atomic disorder into the ordered olivine structure to improve battery performance. [source]

Antimicrobial Gallium-Doped Phosphate-Based Glasses,

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2008
Sabeel P. Valappil
Abstract Novel quaternary gallium-doped phosphate-based glasses (1, 3, and 5 mol % Ga2O3) were synthesized using a conventional melt quenching technique. The bactericidal activities of the glasses were tested against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Clostridium difficile) bacteria. Results of the solubility and ion release studies showed that these glass systems are unique for controlled delivery of Ga3+. 71Ga NMR measurements showed that the gallium is mostly octahedrally coordinated by oxygen atoms, whilst FTIR spectroscopy provided evidence for the presence of a small proportion of tetrahedral gallium in the samples with the highest gallium content. FTIR and Raman spectra also afford an insight into the correlation between the structure and the observed dissolution behavior via an understanding of the atomic-scale network bonding characteristics. The results confirmed that the net bactericidal effect was due to Ga3+, and a concentration as low as 1 mol % Ga2O3 was sufficient to mount a potent antibacterial effect. The dearth of new antibiotics in development makes Ga3+ a potentially promising new therapeutic agent for pathogenic bacteria including MRSA and C. difficile. [source]

Synthesis and Characterization of Hydroxyapatite/Poly(Vinyl Alcohol Phosphate) Nanocomposite Biomaterials

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2008
Nabakumar Pramanik
A hydroxyapatite (HAp)/poly(vinyl alcohol phosphate) (PVAP) nanocomposite has been prepared by a chemical method by varying the HAp content by 10,60% (w/w). The bonding between HAp and PVAP has been investigated through Fourier transform infrared absorption spectra, X-ray diffraction, and thermogravimetric analyses. Transmission electron microscopy study shows a homogeneous dispersion of nanoparticles in the polymer matrix. Scanning electron microscopy study shows enhancement of the surface roughness of the composite with an increase in the nanoparticle content. The mechanical properties of the composites improve significantly with an increase in the HAp content. The HAp/PVAP nanocomposite prepared may have bone,implant applications. [source]

Activated ,,,-Unsaturated Aldehydes as Substrate of Dihydroxyacetone Phosphate (DHAP)-Dependent Aldolases in the Context of a Multienzyme System

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009
Israel Sánchez-Moreno
Abstract The utility for carbon-carbon bond formation of a multienzyme system composed of recombinant dihydroxyacetone kinase (DHAK) from Citrobacter freundii, the fructose bisphosphate aldolase from rabbit muscle (RAMA) and acetate kinase (AK) for adenosine triphosphate (ATP) regeneration has been studied. Several aldehydes with great structural diversity, including three ,,,-unsaturated aldehydes, have been analysed as acceptor substrates. It was found that ,,,-unsaturated aldehydes bearing an electron-withdrawing group in the , position to the double bond with a trans configuration are good acceptors for RAMA in this multienzyme system. The aldol reaction proceeds with excellent D - threo enantioselectivity and the aldol adduct is obtained in good overall yield. The L - threo and D - erythro enantiomers are also accessible from rhamnulose 1-phosphate aldolase (Rha-1PA) and fuculose 1-phosphate aldolase (Fuc-1PA) catalysed reactions, respectively. [source]

Creation of a Monomeric Ruthenium Species on the Surface of Micro-Size Copper Hydrogen Phosphate: An Active Heterogeneous Catalyst for Selective Aerobic Oxidation of Alcohols

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2007
Junhua Liu
Abstract A new micro-size copper hydrogen phosphate (CHP) synthesized by the emulsion method combined with a monomeric ruthenium species was found to be a very effective catalyst for the selective oxidation of alcohols. Several kinds of alcohols were transformed into the corresponding aldehydes or ketones over the RuCHP catalyst by oxygen under very mild conditions. The results showed that the CHP material was perfect as a catalyst support due to its high ion-exchange ability and adsorption capacity. [source]

Economic Evaluation of Oseltamivir Phosphate for Postexposure Prophylaxis of Influenza in Long-Term Care Facilities

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2005
Nancy A. Risebrough MPhil Candidate
Objectives: To compare the cost-effectiveness of oseltamivir postexposure prophylaxis during influenza A outbreaks with that of amantadine postexposure prophylaxis or no postexposure prophylaxis in long-term care facilities (LTCFs). Design: Cost-effectiveness analysis based on decision analytic model from a government-payer perspective. Setting: A Canadian LTCF, with high staff vaccination, at the beginning of influenza season. Participants: Elderly, influenza-vaccinated patients living in a Canadian LTCF. Measurements: Incremental costs (or savings) per influenza-like illness case avoided compared with usual care. Results: From a government-payer perspective, this analysis showed that oseltamivir was a dominant strategy because it was associated with the fewest influenza-like illness cases, with cost savings of $1,249 per 100 patients in 2001 Canadian dollars compared with amantadine and $3,357 per 100 patients compared with no prophylaxis. Costs for amantadine dose calculation and hospitalization for adverse events contributed to amantadine being a more-expensive prophylaxis strategy than oseltamivir. Both prophylaxis strategies were more cost-effective than no prophylaxis. Conclusion: Despite high influenza vaccination rates, influenza outbreaks continue to emerge in LTCFs, necessitating cost-effective measures to further limit the spread of influenza and related complications. Although amantadine has a lower acquisition cost than oseltamivir, it is associated with more adverse events, lower efficacy, and individualized dosing requirements, leading to higher overall costs and more influenza-like illness cases than oseltamivir. Therefore the use of oseltamivir postexposure prophylaxis is more cost-effective than the current standard of care with amantadine prophylaxis or no prophylaxis. [source]

Comparison of alternatives to in-feed antimicrobials for the prevention of clinical necrotic enteritis

JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010
M.S. Geier
Abstract Aims:, The capacity for Lactobacillus johnsonii and an organic acid (OA) blend to prevent Clostridium perfringens -induced clinical necrotic enteritis (NE) in chickens was studied. Methods and Results:, Cobb 500 birds were allocated into six groups (n = 25 birds/pen, eight pens/treatment); Unchallenged, Challenged, Antimicrobial (zinc bacitracin (ZnB)/monensin), OA, probiotic Lact. johnsonii and probiotic sham (Phosphate,buffered saline). All birds were challenged with Eimeria spp. and Cl. perfringens except for unchallenged controls. Birds fed antimicrobials were protected from NE development as indicated by maintenance of body weight, low mortality and clostridium levels, and decreased intestinal macroscopic lesion scores compared to challenged controls (P < 0·05). Lactobacillus johnsonii -fed birds had reduced lesion scores, whilst OA-fed birds had decreased Cl. perfringens levels. Both Lact. johnsonii and OA-fed birds had improved feed efficiency between days 0 and 28 compared to challenged controls; however, mortality and body weights were not improved by either treatment. Microbial profiling indicated that the challenge procedure significantly altered the jejunal microbiota. The microbiota of antimicrobial-fed birds was significantly different from all other groups. Conclusions:, Whilst Lact. johnsonii and OA altered specific intestinal parameters, significant protection against NE was not observed. Significance and Impact of the Study:,Lactobacillus johnsonii and OA did not prevent NE; however, some improvements were evident. Other related treatments, or combinations of these two treatments, may provide greater protection. [source]

Regulation of C-Terminal and Intact FGF-23 by Dietary Phosphate in Men and Women,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2006
Sherri-Ann M Burnett MD
Abstract FGF-23 is a novel regulator of phosphate metabolism. We studied the regulation of FGF-23 by dietary phosphate in 66 men and women using two assays. Dietary phosphate restriction decreased FGF-23 and loading increased FGF-23 significantly. An assay that measured intact FGF-23 showed the effects of dietary phosphate much more clearly than an assay that also measures presumed biologically inactive fragments. Dietary phosphate is a key regulator of circulating FGF-23; choice of assay is critical when studying FGF-23 physiology. Introduction: Fibroblast growth factor 23 (FGF-23) is a novel phosphaturic factor discovered through genetic studies of patients with renal phosphate wasting disorders. Ablation of the FGF-23 gene in mice reduces renal phosphate excretion and increases serum phosphate, suggesting that FGF-23 is critical for normal phosphate homeostasis. We examined the role of dietary phosphate in the regulation of FGF-23 in humans. Materials and Methods: Sixty-six healthy males and females were randomized to either phosphate-depleted or -loaded diets for 5 days, after a 4-day run-in diet. FGF-23 was measured using an "intact" assay that only detects intact FGF-23 peptide and with a "C-terminal" assay that measures both intact FGF-23 peptide and presumed biologically inactive carboxyl terminal fragments. The main outcome was the within group change in FGF-23 with either phosphate depletion or loading. Results: Using the intact FGF-23 assay, mean FGF-23 area under the curve (AUC) decreased by 9 ± 16% with phosphate depletion (p = 0.0041) and increased by 35 ± 29% with loading (p < 0.0001). Using the C-terminal FGF-23 assay, mean FGF-23 AUC decreased by 8 ± 12% with phosphate depletion (p = 0.0003) and increased by 13 ± 20% with loading (p = 0.0016). Increases in FGF-23 with phosphate loading were greater with the intact assay than with the C-terminal assay (p = 0.0003). Using the intact assay only, FGF-23 was significantly associated with serum phosphate (r = 0.39, p < 0.01), 24-h urinary phosphate (r = 0.47, p < 0.01), fractional excretion of phosphate (r = 0.29, p < 0.01), and 1,25-dihydroxyvitamin D (r = ,0.30, p < 0.01). The association between the assays was weak (r = 0.26, p < 0.01). Conclusions: Dietary phosphate is a key regulator of circulating FGF-23 levels in humans. Additionally, choice of assay is critical when performing physiologic investigations of FGF-23. [source]

Phosphate regulates embryonic endochondral bone development

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2009
Alena A. Zalutskaya
Abstract Phosphate is required for terminal differentiation of hypertrophic chondrocytes during postnatal growth plate maturation. In vitro models of chondrocyte differentiation demonstrate that 7,mM phosphate, a concentration analogous to that of the late gestational fetus, activates the mitochondrial apoptotic pathway in hypertrophic chondrocytes. This raises the question as to whether extracellular phosphate modulates chondrocyte differentiation and apoptosis during embryonic endochondral bone formation. To address this question, we performed investigations in the mouse metatarsal culture model that recapitulates in vivo bone development. Metatarsals were cultured for 4, 8, and 12 days with 1.25 and 7,mM phosphate. Metatarsals cultured with 7,mM phosphate showed a decrease in proliferation compared to those cultured in 1.25,mM phosphate. This decrease in proliferation was accompanied by an early enhancement in hypertrophic chondrocyte differentiation, associated with an increase in FGF18 expression. By 8 days in culture, an increase caspase-9 activation and apoptosis of hypertrophic chondrocytes was observed in the metatarsals cultured in 7,mM phosphate. Immunohistochemical analyses of embryonic bones demonstrated activation of caspase-9 in hypertrophic chondrocytes, associated with vascular invasion. Thus, these investigations demonstrate that phosphate promotes chondrocyte differentiation during embryonic development and implicate a physiological role for phosphate activation of the mitochondrial apoptotic pathway during embryonic endochondral bone formation. J. Cell. Biochem. 108: 668,674, 2009. © 2009 Wiley-Liss, Inc. [source]

Phosphate and calcium are required for TGF,-mediated stimulation of ANK expression and function during chondrogenesis

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2010
Paulina Oca
The expression of ANK, a key player in biomineralization, is stimulated by treatment with TGF,. The purpose of this study was to determine whether TGF, stimulation of ANK expression during chondrogenesis was dependent upon the influx of calcium and phosphate into cells. Treatment of ATDC5 cells with TGF, increased ANK expression during all phases of chondrogenic differentiation, particularly at day 14 (proliferation) and day 32 (mineralizing hypertrophy) of culture. Phosphate uptake studies in the presence and absence of phosphonoformic acid (PFA), a competitive inhibitor of the type III Na+/Pi channels Pit-1 and Pit-2, indicated that the stimulation of ANK expression by TGF, required the influx of phosphate, specifically by the Pit-1 transporter, at all phases of differentiation. At hypertrophy, when alkaline phosphatase is highly expressed, inhibition of its activity with levamisole also abrogated the stimulatory effect of TGF, on ANK expression, further illustrating that Pi availability and uptake by the cells is necessary for stimulation of ANK expression in response to TGF,. Since previous studies of endochondral ossification in the growth plate have shown that L-type calcium channels are essential for chondrogenesis, we investigated their role in the TGF,-stimulated ANK response in ATDC5 cells. Treatment with nifedipine to inhibit calcium influx via the L-type channel Cav1.2 (,1C) inhibited the TGF, stimulated increase in ANK expression at all phases of chondrogenesis. Our findings indicate that TGF, stimulation of ANK expression is dependent upon the influx of phosphate and calcium into ATDC5 cells at all stages of differentiation. J. Cell. Physiol. 224: 540,548, 2010. © 2010 Wiley-Liss, Inc. [source]

Protein Hydrolysate of Salted Duck Egg White as a Substitute of Phosphate and Its Effect on Quality of Pacific White Shrimp (Litopenaeus Vannamei)

JOURNAL OF FOOD SCIENCE, Issue 8 2009
Thammarat Kaewmanee
ABSTRACT:, Protein hydrolysate from salted egg white (PHSEW) with different degrees of hydrolysis (DH) (3%, 6%, and 9%) was produced using pepsin. Disappearance of proteins with molecular weight (MW) of 108 and 85 kDa with the concomitant formation of proteins with MW of 23, 20, 13, and 5 kDa was observed in PHSEW. The use of PHSEW for quality improvement of Pacific white shrimp (Litopenaeus vannamei) was investigated. Shrimp soaked in 4% NaCl containing 7% PHSEW and 2.5% mixed phosphates (0.625% sodium acid pyrophosphate [SAPP] and 1.875% tetrasodium pyrophosphate [TSPP]) had the highest cooking yield with the lowest cooking loss (P,< 0.05), compared with shrimps with other treatments. Nevertheless, no difference in weight gain was obtained in comparison with those treated with 4% NaCl containing 3.5% mixed phosphate (P,> 0.05). Cooked shrimp treated with 4% NaCl containing 7% PHSEW and 2.5% mixed phosphate or those treated with 4% NaCl containing 3.5% mixed phosphate had the higher score of appearance, texture, and overall likeness but less shear force, in comparison with the control (no treatment) (P,< 0.05). Microstructure study revealed that muscle fibers of cooked shrimp from both treatments had the swollen fibrils and gaps, while the control had the swollen compact structure. Therefore, use of PHSEW could reduce phosphate residue in shrimps without an adverse effect on sensory properties. [source]

EARLY INITIATION OF PHOSPHATE LOWERING DIETARY THERAPY IN NON-DIALYSIS CHRONIC KIDNEY DISEASE: A CRITICAL REVIEW

JOURNAL OF RENAL CARE, Issue 2009
M.K. Sigrist
SUMMARY Dietary management of hyperphosphatemia and hyperparathyroidism have long been important elements in the clinical management of CKD stage 4 and 5 for the prevention of mineral bone disease. The rationale for phosphate lowering has been further justified, given the accumulating data to support the association of phosphate with vascular damage, in this population who are at high risk of cardiovascular (CV) death. Phosphate is a novel CV risk factor in both CKD and in the general population, and a growing body of literature suggests that high normal serum phosphate may be a risk factor for progression of CKD. Few studies have examined hard outcomes after phosphate lowering. Nonetheless, given the balance of data both in cell, animal and human studies, the use of phosphate lowering strategies at earlier stages of CKD, perhaps even prior to serum phosphate level rising, may well be justified. This review will discuss the complications associated with higher serum phosphate, the potential benefits of early phosphate intervention, practical considerations of low phosphate diets and novel strategies for evaluating these strategies in clinical practice. [source]

A Novel Biphasic Bone Scaffold: ,-Calcium Phosphate and Amorphous Calcium Polyphosphate

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2009
Gaoxiang Chen
Calcium polyphosphate (CPP) was added to hydroxyapatite (HA) to develop a novel biphasic calcium phosphate (BCP). The effects of varying CPP dosage on the sintering property, the mechanical strength, and the phase compositions of HA were investigated. Results showed that CPP reacted with HA and produced ,-calcium phosphate (,-TCP) and H2O and that an excessive dosage of CPP (>10 wt%) obtained a novel BCP of ,-TCP/amorphous-CPP, while a lesser dosage of CPP (<10 wt%) obtained a traditional BCP (HA/,-TCP). The porous ,-TCP/amorphous-CPP scaffolds (porosity of 66.7%, pore diameter of 150,450 ,m, and compressive strength of 6.70±1.5 MPa) were fabricated and their in vitro degradation results showed a significant improvement of degradation with the addition of CPP. [source]

Hydrolysis of ,-Tricalcium Phosphate in Simulated Body Fluid and Dehydration Behavior During the Drying Process

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007
Xiang Wei
The hydrolysis of ,-tricalcium phosphate (,-TCP) in a simulated body fluid (SBF) at 37°C was investigated. The hydration rate was found to be slower in SBF than that in deionized water. The concentration of ions in SBF was monitored by ICP. The hydrolysis product, which was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infra red, and X-ray photoelectron spectroscopy, was determined to be carbonate-containing, calcium-deficient hydroxyapatite (CO3,CDHAp) with Mg2+, Na+, and Cl, impurities similar to the biological apatite. An amorphous layer on the ,-TCP surface was found to be the precursor of the apatite phase, which may either form crystalline apatite or may decompose back to ,-TCP at a lower temperature. [source]