Pr Ion Concentration Research Articles

Enhanced detection of chronic wasting disease in muscle tissue harvested from infected white-tailed deer employing combined prion amplification assays.

Zoonotic transmission of bovine spongiform encephalopathy or mad cow disease, by presumed consumption of infected beef, has increased awareness of the public health risk associated with prion diseases. Chronic wasting disease (CWD) affects moose, elk, and deer, all of which are frequently consumed by humans. Clear evidence of CWD transmission to humans has not been demonstrated, yet, establishing whether CWD prions are present in muscle tissue preferentially consumed by humans is of increasing interest. Conventional assays including immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA) lack the sensitivity to detect low concentrations of prions presumed to be present outside neural or lymphatic tissues. Here we combined two prion amplification assays, the product of protein misfolding cyclic amplification (PMCA) applied directly into real-time quaking induced conversion (RT-QuIC) [denoted now as PQ] to demonstrate the presence of prion seeding activity (i.e. prions) in ~55% of hamstring muscles harvested from CWD-positive white-tailed deer. This compares to prion detection in only 10% of the same samples employing standard RT-QuIC. To determine the extent of CWD dissemination within muscle tissues commonly consumed we tested 7 additional muscles from a subset of deer by PQ. Tongue demonstrated the highest level of prions with ~92% positive. All negative controls remained negative in all PMCA and RT-QuIC assays. We conclude that the combination of PMCA with RT-QuIC readout permits detection of low prion concentrations present in muscle tissue of CWD-infected deer. These findings further demonstrate the utility of amplification assays as tools to detect very low levels of prion burden and supports their use to fill knowledge gaps in our understanding of CWD pathogenesis and zoonotic potential.

Physical properties of Pr3+ substituted zinc spinel (ZnPrxFe2−xO4) nanoferrites synthesized via sol–gel auto-combustion route

Spinel ferrites, a group of metal oxides, have garnered significant attention in the recent decade due to their high demand for numerous applications, including data storage and microwave device applications. In this context, we studied the effect of different doping concentrations of large Pr ions on the physicochemical properties of spinel lattice, such as dielectric and magnetic properties. In this research, we successfully fabricated a series of praseodymium ion-doped zinc spinel ferrites ZnPrxFe2-xO4 nanoparticles 0.00≤x≤0.20 via a simple and economical sol–gel auto-combustion approach. XRD (X-ray Diffraction Analysis) and FTIR investigations validate the presence of a cubical phase, with the crystallite size varying between 11 nm to 19 nm depending on the amount of Pr present. The Scherrer method, Williamson-Hall analysis (WH), and size-strain plot method (SSP) were investigated the correlation of crystalize size. The SSP approach has a better correlation coefficient than the WH method. Transmission electron microscopy TEM shows that the prepared material possessed the cubic and spherical symmetry. The significant variation in electrical parameters was discussed at an applied frequency ranging from 1 MHz to 3 GHz. The dielectric constant is approximately constant in low-frequency regions then relaxation peaks were observed at nearly 1.4 GHz and 2.2 GHz. The dielectric constant and complex dielectric constant of these samples dropped as the praseodymium content increased. Investigations regarding the magnetic properties were carried out using a vibrating sample magnetometer (VSM) at −23 k Oe to +23 k Oe. Low coercivity and relaxation peaks at high frequencies suggest that this material may be suitable for core materials, microwave technologies and recording media.

Effect of Pr ion concentration on the physical properties of KCl0.5Br0.5:0.01Ce3+,XPr3+ crystals

Effect of Pr ion concentration on the physical properties of KCl0.5Br0.5:0.01Ce3+,XPr3+ crystals

Analysis of the unique dependence on oxygen pressure of Pr3+ concentration in the surface of Pr doped ceria

The dependence on oxygen pressure, P(O2), of the Pr3+ concentration, [Pr3+]s, in the surface monomolecular layer of Pr0.1Ce0.9O2-δ, is analyzed. The surface considered, as a core, is negatively charged due to excess Pr3+ ions over oxygen vacancies, VO, while in the bulk the diffuse charge is positive due to excess oxygen vacancies over Pr3+ ions. The [Pr3+]s – P(O2) relations are derived for the full range of reduction of Pr4+ to Pr3+. Under low P(O2), [Pr3+]s reaches the limit of the total concentration of Pr ions. The high P(O2) asymptotic relation is, [Pr3+]s ∝ P(O2)−1/8. This is different from that in the neutral bulk, [Pr3+]b ∝ P(O2)−1/6. For calculating the [Pr3+]s − P(O2) relations the space charge distribution in the bulk need not be fully evaluated.

Unconventional non-Fermi liquid properties of two-channel Anderson impurities system

A theory for treating the unconventional non-Fermi liquid temperature dependence of physical quantities, such as the resistivity, in the Pr-based two-channel Anderson impurities system is developed. It is shown that their temperature dependences are essentially the same as those in the pure lattice system except for the case of extremely low concentration of Pr ions that is difficult to realize by the controlled experiments. This result is consistent with recent observations in diluted Pr-1-2-20 system Y1−x Pr x Ir2Zn20 (x = 0.024, 0.044, 0.085, and 0.44) reported in Yamane et al (2018) Phys. Rev. Lett. 121, 077206, and is quite different from that in the case of single-channel Anderson impurities system in which the crossover between behaviors of the local Fermi liquid and heavy Fermi liquid occurs at around moderate concentration of impurities as observed in Ce-based heavy fermion system La1−x Ce x Cu6.

Effect of Pr ion concentration on the luminescence properties of NaCl:0.01Ce3+,Pr3+ crystals grown in large size

Large size single crystals of NaCl:Ce3+,XPr3+ (with X = 0.0, 0.002, 0.005, 0.008, 0.02, 0.05 and 0.08) were successfully grown by the melt (Czochralski) method and characterized structurally and optically. X-ray diffraction analysis has revealed the incorporation of Ce3+ and Pr3+ ions into the NaCl matrix and the creation of vacancy centers (VʺNa) and positive defects (CeNa●● and PrNa●●) to keep the charge balance. Optical absorption spectral analysis has indicated the presence of absorption peaks at 214, 225, 305, 342, 446, 469, 483 and 592 nm. Photoluminescence (PL) spectral analysis (excited with 259 nm) has revealed dominant emission peaks at 386 and 390 nm due to 5d→4f transition of Ce3+ ions and sharp lines at 479, 491, 532, 600 and 621 nm due to 3P1→3H4, 3P0→3H4, 3P1→3H5, 3P0→3H6 and 3P0→3F2 transitions of Pr3+ ions. The energy transfer mechanism from Ce3+ to Pr3+ in the NaCl crystal has been described and the color coordinates of the luminescence of NaCl:Ce3+,XPr3+ crystals have been calculated by using the emission spectral data. The thermo-luminescence (TL) glow curves of NaCl:Ce3+,XPr3+ crystals obtained show three peaks at about 83, 150 and 239 °C, suitable trap depths induced by Ce3+ and Pr3+ and resulted in the characteristic emission. The TL mechanism of NaCl:Ce3+,XPr3+ crystals has been discussed. The photoluminescence and thermo-luminescence performances have been found to depend strongly on the Pr ion concentration and the maximum intensity has been obtained for the crystal with X = 0.008. Also, the increase in Pr ion concentration has led to gradual decrease of luminescence decay time.

Kinetics and the difference for extraction of praseodymium and neodymium from nitrate aqueous solution by [A336][NO3] using the single drop technique

The kinetics and the difference for Pr(III) and Nd(III) extraction from nitrate aqueous solution using trialkylmethylammonium nitrate ([A336][NO 3 ]) as extractant were investigated by the single drop technique. The dependence of the extraction rate of Pr(III) and Nd(III) on the concentrations of free Pr(III) and Nd(III) ions, the concentrations of NaNO 3 and H + in aqueous solutions, and the concentrations of [A336][NO 3 ] in kerosene solutions were discussed and the corresponding extraction rate equations for Pr(III) and Nd(III) were obtained. These equations demonstrated that the reaction rate constant of Pr(III) with [A336][NO 3 ] was double than that of Nd(III). The effect of the addition of diethylenetriaminepentaacetic acid (DTPA) on the difference in the extraction rate of Pr(III) and Nd(III) by [A336][NO 3 ] was also investigated. It was revealed that the difference in the complex formation rates of Pr(III) and Nd(III) with DTPA made a significant impact on the difference in the extraction rates of Pr(III) and Nd(III) with [A336][NO 3 ]. The ratio of extraction rates of Pr(III) to Nd(III) with [A336][NO 3 ] was in proportion to the ratio of complex formation rates of Pr(III) to Nd(III) with DTPA. The extraction rate difference for Pr(III) and Nd(III) with [A336][NO 3 ] increased due to a higher complex formation rate constant of DTPA with the free and un-complexed Nd(III) ions in the aqueous nitrate solution than that with Pr(III) ions. Therefore, the addition of DTPA in the aqueous nitrate solution is an effective method to intensify the separation of Pr(III) and Nd(III) in kinetics. The study on the extraction mechanism indicated that both the extraction of Pr(III) and Nd(III) by [A336][NO 3 ] were diffusion controlled, and the reactions obeyed S N 2 mechanism. The present work highlights a possible approach to strengthen the kinetic separation of Pr(III) and Nd(III). • The rate equations of Pr(III) and Nd(III) extracted by [A336][NO 3 ] are obtained. • Difference in the extraction rate of Pr(III) and Nd(III) increased due to the addition of DTPA. • Difference in the complexing rate of DTPA with Pr(III) and Nd(III) play a crucial role to intensify kinetic separation. • Extraction of Pr(III) and Nd(III) by [A336][NO 3 ] obeys S N 2 mechanism.

Kinetics of α-synuclein prions preceding neuropathological inclusions in multiple system atrophy.

Multiple system atrophy (MSA), a progressive neurodegenerative disease characterized by autonomic dysfunction and motor impairment, is caused by the self-templated misfolding of the protein α-synuclein. With no treatment currently available, we sought to characterize the spread of α-synuclein in a transgenic mouse model of MSA prion propagation to support drug discovery programs for synucleinopathies. Brain homogenates from MSA patient samples or mouse-passaged MSA were inoculated either by standard freehand injection or stereotactically into TgM83+/- mice, which express human α-synuclein with the A53T mutation. Following disease onset, brains from the mice were tested for biologically active α-synuclein prions using a cell-based assay and examined for α-synuclein neuropathology. Inoculation studies using homogenates prepared from brain regions lacking detectable α-synuclein neuropathology transmitted neurological disease to mice. Terminal animals contained similar concentrations of α-synuclein prions; however, a time-course study where mice were terminated every five days through disease progression revealed that the kinetics of α-synuclein prion replication in the mice were variable. Stereotactic inoculation into the thalamus reduced variability in disease onset in the mice, although incubation times were consistent with standard inoculations. Using human samples with and without neuropathological lesions, we observed that α-synuclein prion formation precedes neuropathology in the brain, suggesting that disease in patients is not limited to brain regions containing neuropathological lesions.

Enhanced detection of prion infectivity from blood by preanalytical enrichment with peptoid-conjugated beads.

Prions cause transmissible infectious diseases in humans and animals and have been found to be transmissible by blood transfusion even in the presymptomatic stage. However, the concentration of prions in body fluids such as blood and urine is extremely low; therefore, direct diagnostic tests on such specimens often yield false-negative results. Quantitative preanalytical prion enrichment may significantly improve the sensitivity of prion assays by concentrating trace amounts of prions from large volumes of body fluids. Here, we show that beads conjugated to positively charged peptoids not only captured PrP aggregates from plasma of prion-infected hamsters, but also adsorbed prion infectivity in both the symptomatic and preclinical stages of the disease. Bead absorbed prion infectivity efficiently transmitted disease to transgenic indicator mice. We found that the readout of the peptoid-based misfolded protein assay (MPA) correlates closely with prion infectivity in vivo, thereby validating the MPA as a simple, quantitative, and sensitive surrogate indicator of the presence of prions. The reliable and sensitive detection of prions in plasma will enable a wide variety of applications in basic prion research and diagnostics.

Preparation and characterization of a novel optical chemical sensor for determination of trace amounts of Praseodymium ion by UV/Vis spectrophotometry

In the present work, a novel optical chemical sensor (optode) was prepared based on impregnation of N, Ń-bis (salicylidene)-1, 3-ethylenediamine (BESA) Schiff base into mesoprous SBA-15 paste for determination of trace amounts of Praseodymium (Pr) ion by UV/Vis spectrophotometry. The sensor was fabricated by dip-coating triacetylcellulose membrane into indicator solution. The proposed optical sensor was prepared through a routine procedure and characterized by various techniques such as ATR-FT-IR and SEM analyses. This optode exhibited a linear range of 10 to 190ngmL−1 for Pr(III) ion concentration with a detection limit of 5.0ngmL−1. The value of the response time for the newly synthesized optode was within 100s while depending on the Pr(III) ion concentration. The proposed optode showed low detection limit, fast response time and high selectivity with respect to the group of transition metal ions (Ce3+, Nb3+, La3+, Cr3+, Zn2+, Hg2+, and Fe2+ ions). The optode was successfully regenerated with a mixture of thiourea and NaOH solution and the response was reversible with the relative standard deviation (R.S.D.) of 1.6%. The optode was stable and stored for at least 17days without any considerable change in its sensitivity. Finally, the developed optode was applied to determine the Pr(III) ions in spiked samples.

Synthesis, Characterization, Optical Properties, and Electron Paramagnetic Resonance for Nano Zn 0 . 5 Co 0 . 5 Fe 2 − x Pr x O 4

Nano ferrite samples of type Zn0.5Co0.5Fe2−x PrxO4, 0 ≤ x ≤ 0.2, were prepared by co-precipitation method for different concentration of Pr ions at a calcination temperature of 823 K. The samples were characterized using x-ray diffraction and transmission electron microscope (TEM), UV spectroscopy, FTIR, and electron paramagnetic resonance (EPR). The increase in concentration of Pr ions shows a significant change in the formed nano ferrite particles size, degree of aggregation, energy band gap, and lattice parameters. X-band (9.24 GHz) EPR spectra at room temperature showed a decrease in the g factor as the Pr content was increased. Furthermore, the variation of the Pr3+ concentration in the samples led to different aggregation states, ranging from isolated nanoparticles with average crystal size of 28.5 to about 15 nm, as confirmed by x-ray diffraction and high-resolution transmission electron microscopy.

Enhanced prion detection in biological samples by magnetic particle extraction and real-time quaking-induced conversion

Prions have been demonstrated in body fluids and excreta using bioassay, but at levels too low for detection by conventional direct-detection assays. More rapid and sensitive detection of prions in these clinically accessible specimens would be valuable for diagnosis and investigations of transmission, environmental impact, and interventions. In addition to very low concentrations of prions, in vitro amplification assays are challenged by the presence of inhibitors in these complex sources. Here, we leverage the prion attribute of avid metal binding with the versatile power of real-time quaking-induced conversion (RT-QuIC) to enhance and simplify detection of chronic wasting-disease prions in biological samples. Iron oxide particle binding and magnetic extraction combined with RT-QuIC permitted rapid analysis of the low concentrations of prions in saliva, urine, faeces, and cerebrospinal fluid. These methods are pertinent to ante-mortem detection, monitoring, and surveillance, and could conceivably be applicable to other protein-misfolding disorders.

Luminescent sintered silica glass prepared by adsorbing Pr ions into mesoporous SiO2–PVA nanocomposite

A monolithic silica glass doped with Pr3+ was prepared by immersing a mesoporous SiO2–polyvinly alcohol (PVA) nanocomposite in a Pr nitrate solution and then sintering it at 1100℃ in air. The sintered glass exhibited pink emission when excited by ultraviolet irradiation. The photoluminescence intensity of the glass depended on the total concentration of Pr ions, which was adjusted by changing the concentration of the Pr nitrate solution and the immersion time. The glass with the highest photoluminescence intensity was prepared by using a 1- or 10-mM Pr solution at an immersion time of 60 min. To reveal how the immersion conditions affected the photoluminescence intensity, we analyzed and discussed the adsorption kinetics of the Pr ions onto the surface of the mesoporous nanocomposite. At immersion times below 60 min, the Pr ions diffused into pores of the nanocomposite without aggregating. To prepare Pr3+-doped silica glass with high photoluminescence, both the concentration of the Pr solution and the immersion time must be controlled.

The energy transfer mechanism in Pr3+and Yb3+codoped β-NaLuF4nanocrystals

The Pr(3+) and Yb(3+) codoped β-NaLuF4 hexagonal nanoplates with a size of 250 nm × 110 nm were synthesized by a solvothermal process. X-Ray diffraction and scanning electron microscopy were used to characterize the crystal structure and morphology of the materials. The visible and near infrared spectra as well as the decay curves of Pr(3+):(3)P0 level were used to demonstrate the energy transfer from Pr(3+) ions to Yb(3+) ions. The downconversion phenomenon has been observed under the direct excitation of the (3)P2 level of Pr(3+). According to the analysis of the dependence of the initial transfer rate upon Yb(3+) ion concentration, it indicates that the ET from Pr(3+) ions to Yb(3+) ions is only by a two-step ET process when the Yb(3+) concentration is very low; however, with the increase of the Yb(3+) concentration, a cooperative ET process occurs and gradually increases; when the Yb(3+) ion concentration increases to 20 mol%, the ET from Pr(3+) ions to Yb(3+) ions occurs only by the cooperative ET process. When the doping concentration of Yb(3+) ions reaches 20 mol% at a fixed concentration of Pr(3+) ions (1 mol%), the theoretical quantum efficiency is 192.2%, close to the limit of 200%. The current research has great potential in improving the conversion efficiency of silicon solar cells.

Rapid Antemortem Detection of CWD Prions in Deer Saliva

Chronic wasting disease (CWD) is an efficiently transmitted prion disease of cervids, now identified in 22 United States, 2 Canadian provinces and Korea. One hallmark of CWD is the shedding of infectious prions in saliva, as demonstrated by bioassay in deer. It is also clear that the concentration of prions in saliva, blood, urine and feces is much lower than in the nervous system or lymphoid tissues. Rapid in vitro detection of CWD (and other) prions in body fluids and excreta has been problematic due to the sensitivity limits of direct assays (western blotting, ELISA) and the presence of inhibitors in these complex biological materials that hamper detection. Here we use real-time quaking induced conversion (RT-QuIC) to demonstrate CWD prions in both diluted and prion-enriched saliva samples from asymptomatic and symptomatic white-tailed deer. CWD prions were detected in 14 of 24 (58.3%) diluted saliva samples from CWD-exposed white-tailed deer, including 9 of 14 asymptomatic animals (64.2%). In addition, a phosphotungstic acid enrichment enhanced the RT-QuIC assay sensitivity, enabling detection in 19 of 24 (79.1%) of the above saliva samples. Bioassay in Tg[CerPrP] mice confirmed the presence of infectious prions in 2 of 2 RT-QuIC-positive saliva samples so examined. The modified RT-QuIC analysis described represents a non-invasive, rapid ante-mortem detection of prions in complex biologic fluids, excreta, or environmental samples as well as a tool for exploring prion trafficking, peripheralization, and dissemination.

A two population model of prion transport through a tunnelling nanotube

This article develops a two prion population model that simulates prion trafficking between an infected dendritic cell and a neuron. The situation when the two cells are connected by a tunnelling nanotube (TNT) is simulated. Two mechanisms of prion transport are considered: lateral diffusion in the TNT membrane and active actin-dependent transport inside endocytic vesicles that are propelled by myosin Va molecular motors. Analytical solutions describing prion concentrations and fluxes are obtained. Numerical results are compared with those predicted by a single prion population model that relies on a single reaction–diffusion equation and accounts for the two modes of prion transport in an effective way.

Correlation analysis for the incubation period of prion disease

Previous studies have shown that genetic quantitative trait loci (QTL), strain barriers, inoculation dose and inoculation method modulate the incubation period of prion diseases. We examined the relationship between a diverse set of physical, genetic and immunological characteristics and the incubation period of prion disease using correlation analyses. We found that incubation period was highly correlated with brain weight. In addition, mean corpuscular volume and cell size were strongly correlated with incubation period, indicating that the physical magnitude of prion-infected organs or individual cells may be important in determining the incubation period. Given the same prion inoculation dose, animals with a lower brain weight, mean corpuscular volume or cell size may experience more virulent disease, as the effective concentration of abnormal prion, which might regulate the attachment rate of prions to aggregates, is increased with smaller capacity of brains and cells. This is partly consistent with previous theoretical modeling. The strong correlations between incubation period and physical properties of the brain and cells in this study suggest that the mechanism underlying prion disease pathology may be physical, indicating that the incubation process is governed by simple chemical stoichiometry.

Application of (1)H and (31)P NMR to topological description of a model of biological membrane fusion: topological description of a model of biological membrane fusion.

The process of biological membrane fusion can be analysed by topological methods. Mathematical analysis of the fusion process of vesicles indicated two significant facts: the formation of an inner, transient structure (hexagonal phase - H(II)) and a translocation of some lipids within the membrane. This shift had a vector character and only occurred from the outer to the inner layer. Model membrane composed of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) was studied. (31)P- and (1)H-NMR methods were used to describe the process of fusion. (31)P-NMR spectra of multilamellar vesicles (MLV) were taken at various temperatures and concentrations of Ca(2+) ions (natural fusiogenic agent). A (31)P-NMR spectrum with the characteristic shape of the H(II) phase was obtained for the molar Ca(2+)/PS ratio of 2.0. During the study, (1)H-NMR and (31)P-NMR spectra for small unilamellar vesicle (SUV), which were dependent on time (concentration of Pr(3+) ions was constant), were also recorded. The presence of the paramagnetic Pr(3+) ions permits observation of separate signals from the hydrophilic part of the inner and outer lipid bilayers. The obtained results suggest that in the process of fusion translocation of phospholipid molecules takes place from the outer to the inner layer of the vesicle and size of the vesicles increase. The NMR study has showed that the intermediate state of the fusion process caused by Ca(2+) ions is the H(II) phase. The experimental results obtained are in agreement with the topological model as well.

Synthesis and characterization of Pr3+-doped glass scintillators prepared by the sol–gel method

Transparent and crack-free Pr-doped silica glass scintillators were successfully synthesized using the sol–gel method. A peak found at 301 nm in the photoluminescence spectrum was ascribed to a radiative transition of the Pr3+ emission center. The associated excitation peak was located at 276 nm. The energy of the excitation peak (4.50 eV) was significantly lower than the energy gap (5.83 eV) of the 1S0 to 3H4 f–f transition. Therefore, the f–f transition was excluded as the origin, and the transition was attributed to 5d–4f. In the absorption spectrum, several bands of the f–f transition were observed. Fourier transform infrared spectroscopy was employed to understand the microstructural features and OH group concentration in the Pr3+-doped silica glass. It was revealed that a Si–O network had been successfully formed, and that the OH group concentration decreased with increasing thermal treatment temperature reaching a saturation value for temperatures higher than 750 °C. The absence of praseodymium oxide nanocrystalline clusters was confirmed by transmission electron microscopy (TEM), even in the sample with the highest Pr ion concentration. Scintillation properties of the Pr3+-doped silica glass were also characterized. The scintillation decay time constants were estimated to be approximately 1.3 and 14 ns, which supports the assignment of the luminescence to the 5d–4f transition. The scintillation light yield of the Pr3+-doped silica glass was estimated to be approximately 130 photons/MeV.

Survival of infectious prions in water

The objective of this study was to evaluate the fate of infectious prions in water. Known concentrations of infectious prions were added to deionized water, tap water, and wastewater. Samples were incubated at 25°C, 37°C, and 50°C for 1 to 8 weeks. The standard scrapie cell assay (SSCA) which includes the ELISPOT (Enzyme Linked Immuno-Spot) reaction was performed to determine prion infectivity and quantity as a function of time. A reduction of infectious prions was observed at 25°C, 37°C, and 50°C ranging between 0.5-log10 and 1.4-log10 in one week. Results suggest that organic matter was instrumental in protecting infectious prions, allowing them to remain infectious for a longer period of time. Thus, our data effectively show a quantifiable reduction of infectious prions in water and identifies some of the components that may influence infectivity.