Distribution Of Gd Research Articles

First gadolinium loading to Super-Kamiokande

In order to improve Super-Kamiokande’s neutron detection efficiency and to thereby increase its sensitivity to the diffuse supernova neutrino background flux, 13 tons of Gd2(SO4)3⋅8H2O (gadolinium sulfate octahydrate) was dissolved into the detector’s otherwise ultrapure water from July 14 to August 17, 2020, marking the start of the SK-Gd phase of operations. During the loading, water was continuously recirculated at a rate of 60 m3/h, extracting water from the top of the detector and mixing it with concentrated Gd2(SO4)3⋅8H2O solution to create a 0.02% solution of the Gd compound before injecting it into the bottom of the detector. A clear boundary between the Gd-loaded and pure water was maintained through the loading, enabling monitoring of the loading itself and the spatial uniformity of the Gd concentration over the 35 days it took to reach the top of the detector. During the subsequent commissioning the recirculation rate was increased to 120 m3/h, resulting in a constant and uniform distribution of Gd throughout the detector and water transparency equivalent to that of previous pure-water operation periods. Using an Am–Be neutron calibration source the mean neutron capture time was measured to be 115±1 μs, which corresponds to a Gd concentration of 111±2 ppm, as expected for this level of Gd loading. This paper describes changes made to the water circulation system for this detector upgrade, the Gd loading procedure, detector commissioning, and the first neutron calibration measurements in SK-Gd.

Costos energéticos y económicos de los motocultores YTO DF 15L y DONGFENG DF 151L en la preparación de suelos

The objective of this study was to determine the energy and economic cost of the YTO DF 15L and DONGFENG DF 151L mechanized agricultural sets (double pass of rotovator) in the work of preparation of sandy-clay and loamy-clay soils, respectively. The methodology for determining total energy costs (MJ.h-1) and per worked area (MJ.ha-1) was used; likewise, Cuban Standard NC 34-38:2003 allowed the calculation of total economic costs (USD.h-1) and per worked area (USD.ha-1). The main findings showed that the total energy cost (EST) reached values of 78.50 and 75.30 MJ. h-1, with the energy sequestered by fuel (ESc) indicator prevailing with a share of 55 and 58.4%, in the EST structure, the energy costs per worked area EST (ha) registered 1.574,00 and 1.883,00 MJ.ha-1. On the other hand, the direct operating cost (Gd), reported 5.31 and 5.68 USD.h-1, with the cost per salary (Gs), the indicator that predominated with 68.and 70.4% in the distribution of Gd, and the cost per worked area (Gex), presented figures of 106.20 and 142.00 USD.ha-1, for the YTO DF 15L and DONGFENG DF 151L sets, respectively. The YTO DF 15L power tiller, with rotovator, distinguished itself as the agricultural set with the lowest EST (ha) and Gex, by 16 and 25%, respectively, in the agricultural operation provided.

High Spatial Resolution Neutron Transmission Imaging Using a Superconducting Two-Dimensional Detector

Neutron imaging is one of the most powerful tools for nondestructive inspection owing to the unique characteristics of neutron beams, such as high permeability for many heavy metals, high sensitivity for certain light elements, and isotope selectivity owing to a specific nuclear reaction between an isotope and neutrons. In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method for the pulsed neutron source. We obtained the neutron transmission images of a Gd–Al alloy sample, inside which single crystals of GdAl <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_3$</tex-math></inline-formula> were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al–Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{155}$</tex-math></inline-formula> Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m × 12 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m. Gd selective imaging was performed using the resonance dip of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{155}$</tex-math></inline-formula> Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.

Urban geochemistry and human-impacted imprint of dissolved trace and rare earth elements in a high-tech industrial city, Suzhou

Due to the rapid urbanization process, the consumption of trace and rare earth elements has dramatically increased. Although some elements have been extensively studied due to their high biological toxicity, most elements are ignored and taken seriously in recent years. Here, we investigated the urban geochemistry, source, and anthropogenic responding factor for 15 trace elements (Cd, Pb, Co, Sn, Cu, Ni, V, As, Mo, Sb, Al, Li, Fe, Zn, and Sr) and rare earth elements in surface water of the Suzhou city. The percentage of anthropogenic gadolinium vary from 46.9% (YCH-2) to 92.8% (WS-2), while the analysis of variance shows that human activities may affect the distribution of Cd, Co, Sn, Ni, As, Li, Fe, and Sr. Three clusters are obtained from the correlation and cluster analysis. The Cluster 1 with a significant positive correlation of Pb, Cd, Gd, Li, Sr, Co, Fe, Ni, and Sn reflecting these elements are dominantly influenced by urban sewage and industrial activities. The Cluster 2 (Zn, Cu, and Al) can be attributed to geologic sources, while the Cluster 3 (V, Mo, As, and Sb) indicate the combined action of agricultural and urban activities. The Gd versus Li plot showed a significant positive correlation, which can be used as a new indicator to trace the anthropogenic impact on urban waters. Overall, this study provides clear evidence that the content and distribution of Gd and Li are deeply affected by human activities in a high-tech industrial city (Suzhou), which can be regarded as emerging elements contaminations.

Gadolinium distribution in kidney tissue determined and quantified by micro synchrotron X-ray fluorescence.

Aims of this study were to investigate gadolinium (Gd) in kidney tissue from a female patient with severe renal failure, who had a magnetic resonance imaging (MRI) with Gd-based contrast agent (GBCA) three times prior to kidney transplantation. Secondly to assess (semi-)quantitatively the Gd concentration in renal tissue and the spatial distribution of Gd in association to suspected co-elements such as calcium (Ca) and zinc (Zn). Archival paraffin embedded kidney tissue was investigated by micro Synchrotron X-ray fluorescence (µSRXRF) at the DORIS III storage ring at beamline L, HASYLAB/DESY(Hamburg, Germany). Elementary gadolinium (Gd) could be demonstrated in a near histological resolution in areas of about 2 × 1.5 mm2 of size. Mean Gd resulted in 200ppm with a huge width of distribution (Gd-max: 2000ppm). In kidney cortex Gd was in-homogeneously, but not randomly, distributed. Gd was verified throughout the investigated tissue. Low Gd was predominately concentrated either in areas with focally atrophic tubules or in areas with totally preserved uriniferous tubes. Moreover, strong correlations existed between Gd and calcium (Ca) or Gd and zinc (Zn) or Gd and strontium (Sr) distribution. Throughout our analysed areas copper (Cu) was nearly homogeneously distributed and Cu association to Gd could not be established, and also not for Gd to Fe. Gd in glomeruli was relatively reduced compared with mean Gd-values, while iron (Fe) distribution clearly demarks glomeruli mostly due to red blood cell iron in these capillary convolutes. Quantitative µSRXRF analysis provided an insight in element spatial distribution of Gd in the renal cortex. The strong correlation of the spatial distribution and associations between elements like Ca, Zn and Sr let us suspect that these elements are involved in the cell metabolism of GBCA. Low Gd in areas with extreme fibrosis and tubule atrophy or in areas with histologically intact tubes, let us suspect that on the one side Gd cannot be transported and deposited into these tissue areas and on the other side we assume that intact renal tubes do not reabsorb and store excreted Gd.

Effects of content and distribution of Zn and Gd on formation ability of I phase and W phase in Mg‒Zn‒Gd‒Zr alloy

The solid solution and compounds in Mg‒Zn‒Gd‒Zr magnesium alloy semicontinuous casting ingots were effectively separated by phase separation technique，the solid solution quantity of Zn and Gd as well as the mass ratio of Mg3GdZn6 (I phase) and Mg3Gd2Zn (W phase) compounds were determined, and the mass fraction of I phase and W phase were calculated. The results show that increasing the initial Zn/Gd ratio in as-cast alloys increases the ratio of I and W phases, increasing the content of Zn and Gd under a certain Zn/Gd ratio increases the amount of I and W phases simultaneously. I phase and W phase form in the residual melt of primary α-Mg crystallization, the changes of the distribution of Zn and Gd in the alloy will affect the composition of the residual melt, thus affecting the forming ability of I phase and W phase. After homogenization, I phase disappears, W phase increases and total amount of ternary phase decreases. The Gd element in the newly formed W phase comes from the decomposed I phase and the supersaturate solid solution, while the Zn decomposed from I phase and more than that required for the newly formed W phase diffused to the solid solution.

Microdistribution of Magnetic Resonance Imaging Contrast Agents in Atherosclerotic Plaques Determined by LA-ICP-MS and SR-\u03bcXRF Imaging

PurposeContrast-enhanced magnetic resonance imaging (MRI) has the potential to replace angiographic evaluation of atherosclerosis. While studies have investigated contrast agent (CA) uptake in atherosclerotic plaques, exact CA spatial distribution on a microscale is elusive. The purpose of this study was to investigate the microdistribution of gadolinium (Gd)- and iron (Fe) oxide-based CA in atherosclerotic plaques of New Zealand White rabbits.ProceduresThe study was performed as a post hoc analysis of archived tissue specimens obtained in a previous in vivo MRI study conducted to investigate signal changes induced by very small superparamagnetic iron oxide nanoparticles (VSOP) and Gd-BOPTA. For analytical discrimination from endogenous Fe, VSOP were doped with europium (Eu) resulting in Eu-VSOP. Formalin-fixed arterial specimens were cut into 5-μm serial sections and analyzed by immunohistochemistry (IHC: Movat’s pentachrome, von Kossa, and Alcian blue (pH 1.0) staining, anti-smooth muscle cell actin (anti-SMA), and anti-rabbit macrophage (anti-RAM-11) immunostaining) and elemental microscopy with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and synchrotron radiation μX-ray fluorescence (SR-μXRF) spectroscopy. Elemental distribution maps of Fe, Eu, Gd, sulfur (S), phosphorus (P), and calcium (Ca) were investigated.ResultsIHC characterized atherosclerotic plaque pathomorphology. Elemental microscopy showed S distribution to match the anatomy of arterial vessel wall layers, while P distribution corresponded well with cellular areas. LA-ICP-MS revealed Gd and Fe with a limit of detection of ~ 0.1 nmol/g and ~ 100 nmol/g, respectively. Eu-positive signal identified VSOP presence in the vessel wall and allowed the comparison of Eu-VSOP and endogenous Fe distribution in tissue sections. Extracellular matrix material correlated with Eu signal intensity, Fe concentration, and maximum Gd concentration. Eu-VSOP were confined to endothelium in early lesions but accumulated in cellular areas in advanced plaques. Gd distribution was homogeneous in healthy arteries but inhomogeneous in early and advanced plaques. SR-μXRF scans at 0.5 μm resolution revealed Gd hotspots with increased P and Ca concentrations at the intimomedial interface, and a size distribution ranging from a few micrometers to submicrometers.ConclusionsEu-VSOP and Gd have distinct spatial distributions in atherosclerotic plaques. While Eu-VSOP distribution is more cell-associated and might be used to monitor atherosclerotic plaque progression, Gd distribution indicates arterial calcification and might help in characterizing plaque vulnerability.

Comprehensive phenotyping revealed transient startle response reduction and histopathological gadolinium localization to perineuronal nets after gadodiamide administration in rats

Gadolinium based contrast agents (GBCAs) are widely used in clinical MRI since the mid-1980s. Recently, concerns have been raised that trace amounts of Gadolinium (Gd), detected in brains even long time after GBCA application, may cause yet unrecognized clinical consequences. We therefore assessed the behavioral phenotype, neuro-histopathology, and Gd localization after repeated administration of linear (gadodiamide) or macrocyclic (gadobutrol) GBCA in rats. While most behavioral tests revealed no difference between treatment groups, we observed a transient and reversible decrease of the startle reflex after gadodiamide application. Residual Gd in the lateral cerebellar nucleus was neither associated with a general gene expression pathway deregulation nor with neuronal cell loss, but in gadodiamide-treated rats Gd was associated with the perineuronal net protein aggrecan and segregated to high molecular weight fractions. Our behavioral finding together with Gd distribution and speciation support a substance class difference for Gd presence in the brain after GBCA application.

Chemical Solution Deposition of YBCO Films with Gd Excess

Chemical solution deposition of Gd-doped YBCO, Y1GdyBa2Cu3O7−δ, (YBCO-Gd), film was carried out following the metal-organic decomposition approach and in situ route. Two dopant concentrations, 5 and 10 mol %, were evaluated. The morphology and crystalline structure of the superconductor films were deeply investigated. In general, a homogeneous and well c-axis oriented film was observed by using scanning and transmission electron microscopy (SEM and TEM) and X-ray diffraction. However, compared to pure YBCO, YBCO-Gd samples showed an increased stacking faults concentration, as recognized by TEM. X-ray photoelectron spectroscopy allowed studying the Gd distribution in the films and gathered information about the Gd electronic environment. Superconducting properties were evaluated at different temperatures, magnetic field directions, and intensities. Higher zero-field critical current densities were measured with respect to undoped samples in the temperature range from 10 to 77 K with both Gd concentrations (i.e., 28, 27, and 13 MA·cm−2, respectively, for YBCO-Gd 5%, YBCO-Gd 10%, and undoped YBCO at 10 K in self field condition). At low temperatures, this improvement was maintained up to 12 T, confirming the efficacy of Gd addition for the enhancement of transport properties of YBCO film.

Fast whole brain MR imaging of dynamic susceptibility contrast changes in the cerebrospinal fluid (cDSC MRI).

The circulation of cerebrospinal fluid (CSF) is closely associated with many aspects of brain physiology. When gadolinium(Gd)-based contrast is administered intravenously, pre- and post-contrast MR signal changes can often be observed in the CSF at certain locations within the intra-cranial space, mainly due to the lack of a blood-brain barrier in the dural blood vessels. This study aims to develop and systemically optimize MRI sequences that can detect dynamic signal changes in the CSF after Gd administration with a sub-millimeter spatial resolution, a temporal resolution of <10s, and whole brain coverage. Bloch simulations were performed to determine optimal imaging parameters for maximum CSF contrast before and after Gd injection. Simulations were validated with phantom scans. An optimized turbo-spin-echo (TSE) sequence was performed on healthy volunteers on 3T and 7T. Simulation results agreed well with phantom scans. In human scans, dynamic signal changes after Gd injection in the CSF were detected at several locations where cerebral lymphatic vessels were identified in previous studies. The concentration of Gd in CSF in these regions was estimated to be approximately 0.2 mmol/L. Dynamic signal changes induced by the distribution of Gd in the CSF can be detected in healthy human subjects with an optimized TSE sequence. The proposed methodology does not rely on any particular theory on CSF circulation. We expect it to be useful for studies on CSF circulation and cerebral lymphatic vessels in the brain.

Extraction of Lanthanides(III) from Nitric Acid Solutions with Tetraphenylmethylenediphosphine in the Presence of Bis[(trifluoromethyl)sulfonyl]imides of Quaternary Ammonium Bases

The interphase distribution of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu between aqueous HNO3 solutions and solutions of tetraphenylmethylenediphosphine dioxide in 1,2-dichloroethane was studied. The latter solutions also contained ionic liquids with an anion of bis[(trifluoromethyl)sulfonyl]imide and cations of quaternary ammonium bases. It was detected that the extraction of metal ions significantly increases in the presence of ionic liquids in the organic phase. The stoichiometry of the extracted complexes was determined, and analysis was made of the effect of the HNO3 concentration in the aqueous phase and the nature of the cationic part of an ionic liquid on the efficiency of the extraction of metal ions into the organic phase.

Gadolinium Retention in Erythrocytes and Leukocytes From Human and Murine Blood Upon Treatment With Gadolinium-Based Contrast Agents for Magnetic Resonance Imaging.

Being administered intravenously, the tissue that gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging mostly encounter is blood. Herein, it has been investigated how much Gd is internalized by cellular blood components upon the in vitro incubation of GBCAs in human blood or upon intravenous administration of GBCAs to healthy mice. We report results that show how the superb sensitivity of inductively coupled plasma-mass spectrometry (ICP-MS) allows the detection of very tiny amounts of GBCAs entering red blood cells (RBCs) and white blood cells (WBCs). This finding may introduce new insights in the complex matter relative to excretion and retention pathway of administered GBCAs. The study was tackled by 2 independent approaches. First, human blood was incubated in vitro with 5 mM of GBCAs (gadoteridol, gadobenate dimeglumine, gadodiamide, and gadopentetate dimeglumine) for variable times (30 minutes, 1 hour, 2 hours, and 3 hours) at 37°C. Then, blood cell components were isolated by using the Ficoll Histopaque method, washed 3 times, mineralized, and analyzed by ICP-MS for total Gd quantification. Furthermore, blood components derived from human blood incubated with gadodiamide or gadoteridol underwent UPLC-MS (ultra performance liquid chromatography-mass spectrometry) analysis for determination of the amount of intact Gd-DTPA-BMA and Gd-HPDO3A. Second, the distribution of Gd in the blood components of healthy CD-1 mice was administered intravenously with a single dose (1.2 mmol/kg) of gadodiamide or gadoteridol. Blood samples were separated and processed at different time points (24 hours, 48 hours, 96 hours, and 10 days after GBCA administration). As for human blood, ICP-MS quantification of total Gd and UPLC-MS determination of the amount of intact GBCAs were carried out. The amount of Gd taken up by RBCs and WBCs was well detectable by ICP-MS. The GBCAs seem to be able to cross the membrane by diffusion (RBCs) or, possibly, by macropinocytosis (WBCs). Ex vivo studies allowed it to be established that the structure of the different GBCAs were not relevant to determine the amount of Gd internalized in the cells. Although the amount of Gd steadily decreases over time in gadoteridol-labeled cells, in the case of gadodiamide, the amount of Gd in the cells does not decrease (even 10 days after the administration of the GBCA). Moreover, while gadoteridol maintains its structural integrity upon cellular uptake, in the case of gadodiamide, the amount of intact complex markedly decreases over time. The detection of significant amounts of Gd in RBCs and WBCs indicates that GBCAs can cross blood cell membranes. This finding may play a role in our understanding of the processes that are at the basis of Gd retention in the tissues of patients who have received the administration of GBCAs.

Gadolinium accumulation, distribution, chemical forms, and influence on the growth of rice seedlings

The content of gadolinium (Gd) is continuously increased in environment, which potentially threatens human health and ecological equilibrium. However, the phytotoxicity of Gd on plants remains unknown until now. In this study, the accumulation, distribution, and chemical forms of Gd as well as its influence on growth and nutrient balance were systematically studied in rice seedlings after the treatments of different concentrations of Gd (0, 1, 10, 100, and 1000 μM) for 10 days. The results showed that most Gd was accumulated in the roots and only a little percentage of Gd was transported to shoots. The accumulation of Gd was increased in a dose-dependent manner in various chemical forms and subcellular fractions. More than 80% of Gd was in the forms of insoluble oxalates and phosphates. Gd was mainly compartmentalized in the cell wall, and the content of Gd was increased with increasing concentrations of Gd. In addition, hormetic effects of Gd were found on rice growth. The growth of rice was induced by the lower concentration of Gd, but inhibited by the higher concentration of Gd. The results indicated that rice seedlings could cope with Gd toxicity through cell wall compartmentalization as well as forming of precipitates with oxalate and phosphate.

Effect of Gd and Nb on dielectric and magnetic transition temperature of BaTiO3- Li0.5Fe2.5O4 composites

The Gd and Nb doped 90 BaTiO3- 10 Li0.5Fe2.5O4 composites are prepared using solid state technique. The structural, functional, dielectric, magnetic and magneto-electric properties of Gd and Nb doped 90 BaTiO3- 10 Li0.5Fe2.5O4 have been studied using X-ray diffraction, FTIR, dielectric spectrometer, vibrating sample magnetometer and DSP lock-in amplifier respectively. The XRD peaks indicate the absence of impurities in the undoped and doped BLF composite which confirms the high crystalline nature of all the composites. The FTIR spectrum reveals a strong absorption bands at 468 cm−1 and 853 cm−1. The transition temperature of BLF decreases slightly and the dielectric constant of all composites is maximum for different temperatures at fixed frequency due to mechanical strain in the grains and inhomogeneous distribution of Gd and Nb ions in place of Ti. The dielectric dissipation (tan δ) of BLF decreases with increase in the concentration of Gd and Nb in BLF which indicates the less number of defects like oxygen vacancies in BLF. The magnetic transition increases with increase in the concentration of Gd and Nb in BLF composites and this increase of the magnetic transition may due to the presence of exchange interaction between Fe3+ and Gd 3+, Nb5+ ions through neighboring octahedrons. The M-E coefficient of BLF decreases after doping Gd, Nb in BLF which may be due to the resistivity of ferroelectric phase greater than ferrite phase.

Computational assessment of the cellular dosimetry and microdosimetry of the gadolinium electrons released during neutron capture therapy

One of the challenges in radiobiology is the determination of the dose of Auger electrons in cellular-molecular dimensions and evaluation of their relative biological effectiveness (RBE). In this study, we try to assess the cellular dosimetry and microdosimetry of the internal conversion (IC) and Auger electrons released during Gadolinium-157 neutron capture reaction (157GdNCR) using the low-energy physics models included in Geant4 toolkit and MCNPX code. The results show that the MCNPX code does not have reliable results for the cellular dosimetry of low-energy electrons compared to the validated low-energy Geant4 physics models. Although the use of the Geant4-DNA models is a necessity in microdosimetric calculations, due to the time-consuming run of the Geant4-DNA models in the cellular dosimetry calculations, the use of Geant4-Penelope and Geant4-Livermore models can lead to the quick and reliable results. The results show that, with appropriate selection of physical parameters, the results of small-scale microdosimetry calculated using the CH models in Geant4 approach the results of Geant4-DNA. With regard to the cellular dosimetry results, the amount of the absorbed dose in the nucleus of a cell is strongly dependent on the distribution of Gd in the different compartments of the cell. The cross-dose in the nucleus from the Gd electrons released in adjacent cells is comparable to the self-dose of the nucleus to nucleus and noteworthy to destroy the quiescent cancer cells that do not accumulate Gd. The microdosimetry results show that, unlike the absorbed dose in DNA, RBE is not much dependent on the Gd distribution relative to the DNA within the molecular dimensions. If Gd is distributed at the center of the DNA, the absorbed dose of Gd electrons in the DNA (246 kGy) with a quality-factor-equivalent RBE of 7.93 is sufficiently large for the double-strand breaks (DSBs) of the DNA.

Enhancing and verification of dose in external radiation therapy using Gd nanoparticles as a theranostic agent: A Monte Carlo simulation study

Introduction: Theranostics, in particular, the use of radionuclides with the capability of simultaneous imaging and treatment has opened new horizons in personalized treatment planning of targeted radiation therapy. In this approach, positive beta or gamma emitters are required for imaging and alpha, beta and Auger electrons for treatment purpose. On the other hand, studies have shown that due to high biological effectiveness the combination of external radiation modalities such as neutrons and protons with internal radiation modalities, can have a potential impact on cancer cell killing. Therefore, given the advances made in nanoparticles and radiopharmaceuticals, the necessity of designing combined therapy modalities and radiopharmaceuticals with a diagnostic-therapeutic capability is of particular importance, and Monte Carlo computational methods are a powerful tool in this regard. Materials and Methods: In this study, by using the Geant4 and MCNPX Monte Carlo Codes, the absorbed dose of the Auger electrons, KERMA and the flux of the prompt gamma photons was calculated. the distribution of gadolinium nanoparticles with different concentrations and also without them, in two geometries of uniform PMMA environments surrounded by water and the cell model, was subjected to neutron irradiation and the dose was measured in macroscopic and microscopic conditions. Regarding the higher energy range compared to the diagnostic items in nuclear medicine, a gamma camera was optimized for counting the prompt gamma photons by using the F4 and F2 flux calculations as well as count calculation F1 MCNP tallies Results: Dose enhancement was observed in micro and macro dosimetry conditions. For example, the amount of dose in the cellular model assigned to the nucleus was 5.1 E-5 Gy, 3.01E-03 Gy, and 4.05E-7 Gy for the distribution of Gd in the core, total nucleus, and cytoplasm for particle history, respectively. There was also a direct correlation between the number of prompt gamma rays and the nanoparticle concentration Conclusion: Labeling of antibodies or peptides with gadolinium nanoparticles in the presence of external radiation beam can be used as a marker for drug distribution, as well as targeted radiation therapy theranostic agent because of enhancement of doses due to auger electrons and prompt gamma photons with imaging capability that showing the synergy impact of diagnostic imaging and therapeutics.

Does Age Interfere With Gadolinium Toxicity and Presence in Brain and Bone Tissues?

The main objective of the study was to assess the effect of age on target tissue total gadolinium (Gd) retention after repeated administration of gadodiamide (linear) or gadoterate (macrocyclic) Gd-based contrast agent (GBCA) in rats. The secondary objective was to assess the potential developmental and long-term consequences of GBCA administration during neonatal and juvenile periods. A total of 20 equivalent human clinical doses (cumulated dose, 12 mmol Gd/kg) of either gadoterate or gadodiamide were administered concurrently by the intravenous route to healthy adult and juvenile rats. Saline was administered to juvenile rats forming the control group. In juvenile rats, the doses were administered from postnatal day 12, that is, once the blood-brain barrier is functional as in humans after birth. The tests were conducted on 5 juvenile rats per sex and per group and on 3 adult animals per sex and per group. T1-weighted magnetic resonance imaging of the cerebellum was performed at 4.7 T during both the treatment and treatment-free periods. Behavioral tests were performed in juvenile rats. Rats were euthanatized at 11 to 12 weeks (ie, approximately 3 months) after the last administration. Total Gd concentrations were measured in plasma, skin, bone, and brain by inductively coupled plasma mass spectrometry. Cerebellum samples from the juvenile rats were characterized by histopathological examination (including immunohistochemistry for glial fibrillary acidic protein or GFAP, and CD68). Lipofuscin pigments were also studied by fluorescence microscopy. All tests were performed blindly on randomized animals. Transient skin lesions were observed in juvenile rats (5/5 females and 2/4 males) and not in adult rats having received gadodiamide. Persisting (up to completion of the study) T1 hyperintensity in the deep cerebellar nuclei (DCNs) was observed only in gadodiamide-treated rats. Quantitatively, a slightly higher progressive increase in the DCN/brain stem ratio was observed in adult rats compared with juvenile rats, whereas no difference was noted visually. In all tissues, total Gd concentrations were higher (10- to 30-fold higher) in the gadodiamide-treated groups than in the gadoterate groups. No age-related differences were observed except in bone marrow where total Gd concentrations in gadodiamide-treated juvenile rats were higher than those measured in adults and similar to those measured in cortical bone tissue. No significant treatment-related effects were observed in histopathological findings or in development, behavior, and biochemistry parameters. However, in the elevated plus maze test, a trend toward an anxiogenic effect was observed in the gadodiamide group compared with other groups (nonsignificant). Moreover, in the balance beam test, a high number of trials were excluded in the gadodiamide group because rats (mainly males) did not completely cross the beam, which may also reflect an anxiogenic effect. No T1 hyperintensity was observed in the DCN after administration of the macrocyclic GBCA gadoterate regardless of age as opposed to administration of the linear GBCA gadodiamide. Repeated administration of gadodiamide in neonatal and juvenile rats resulted in similar total Gd retention in the skin, brain, and bone to that in adult rats with sex having no effect, whereas Gd distribution in bone marrow was influenced by age. Further studies are required to assess the form of the retained Gd and to investigate the potential risks associated with Gd retention in bone marrow in juvenile animals treated with gadodiamide. Regardless of age, total Gd concentration in the brain and bone was 10- to 30-fold higher after administration of gadodiamide compared with gadoterate.

Tracking hospital effluent-derived gadolinium in Atlantic coastal waters off Brazil

The use of gadolinium (Gd) complexes as contrast agents in magnetic resonance imaging (MRI) has resulted in point source releases of anthropogenic Gd into the environment and presents the opportunity to trace the fate of wastewater plumes. Here we collected seawater samples along the coast of Northeast Brazil to investigate the influence of two submarine sewage outfalls on the distribution of Gd and other rare earth elements (REE) in the coastal waters. The shale-normalized REEs only show a small light over heavy REE enrichment and negative Ce anomalies, likely reflecting the influence of freshwater inputs. Positive Gd anomalies are observed at most of the sampling sites, indicating the ubiquitous presence of anthropogenic Gd in coastal waters. The highest Gd anomalies are found in the vicinity of the submarine sewage outfalls and decrease with increasing distance from point source. The total daily discharge of 216 ± 82 g Gd and 92.0 ± 19.3 g Gd was calculated for the Rio Vermelho (ERV) and Boca do Rio (EBR) submarine outfalls, respectively, which on population bases equates to 11.5 ± 4.3 g Gd d−1 for ERV and 15.5 ± 3.3 g Gd d−1 for EBR per 100 000 persons. It is estimated that in 2016 the annual emission of anthropogenic Gd by hospitals and clinics in Brazil varied between 527 kg and 5.3 tons. It was roughly estimated that between 698 and 2021 g Gd d−1 are discharged into the Tropical and South Atlantic waters due to submarine outfall sewage along the coast of Brazil.

Distribution of Gd(III) ions at the graphene oxide/water interface

Graphene oxide (GO) have emerged recently as a novel material for sorbing metal cations from aqueous media. However, the literature data on sorption capacity differ by more than one order in magnitude, and the nature of the chemical bonding between GO and metal cations remains unclear. In this work we show that Gd3+ ions are bound to GO by both coordinate-covalent bonding and electrostatic attraction with prevailing the former. We provide the complete account for the GO sorption toward Gd3+ as the function of the Gd3+/GO ratio and pH of solution. The upper limits of the strong bonding are determined as 0.70 and 0.16 mmol(Gd3+)/g(GO) in the neutral and in the intrinsically acidic solutions, respectively. At large excess of Gd3+ in the neutral solutions, the sorption capacity reaches 1.45 mmol(Gd3+)/g(GO). The effectiveness of water, hydrochloric acid and EDTA as desorbing eluents is compared. We experimentally demonstrate the existence of the Gd3+ concentration gradient within the diffuse layer at the GO/water interface, and its exponential character on the distance from the GO surface. The thickness of the diffuse layer and the position of the slipping plane are estimated. Such characteristics, typical for colloid systems, show that in solutions, GO flakes form distinct phase, even though they are just one atom thick.

Histology and Gadolinium Distribution in the Rodent Brain After the Administration of Cumulative High Doses of Linear and Macrocyclic Gadolinium-Based Contrast Agents

Retrospective studies in patients with primary brain tumors or other central nervous system pathologies as well as postmortem studies have suggested that gadolinium (Gd) deposition occurs in the dentate nucleus (DN) and globus pallidus (GP) after multiple administrations of primarily linear Gd-based contrast agents (GBCAs). However, this deposition has not been associated with any adverse effects or histopathological alterations. The aim of this preclinical study was to systematically examine differences between linear and macrocyclic GBCAs in their potential to induce changes in brain and skin histology including Gd distribution in high spatial resolution. Fifty male Wistar-Han rats were randomly allocated into control (saline, n = 10 rats) and 4 GBCA groups (linear GBCAs: gadodiamide and gadopentetate dimeglumine, macrocyclic GBCAs: gadobutrol and gadoteridol; n = 10 rats per group). The animals received 20 daily intravenous injections at a dose of 2.5 mmol Gd/kg body weight. Eight weeks after the last GBCA administration, the animals were killed, and the brain and skin samples were histopathologically assessed (hematoxylin and eosin; cresyl violet [Nissl]) and by immunohistochemistry. The Gd concentration in the skin, bone, brain, and skeletal muscle samples were analyzed using inductively coupled plasma mass spectroscopy (ICP-MS, n = 4). The spatial Gd distribution in the brain and skin samples was analyzed in cryosections using laser ablation coupled with ICP-MS (LA-ICP-MS, n = 3). For the ultra-high resolution of Gd distribution, brain sections of rats injected with gadodiamide or saline (n = 1) were assessed by scanning electron microscopy coupled to energy dispersive x-ray spectroscopy and transmission electron microscopy, respectively. No histological changes were observed in the brain. In contrast, 4 of 10 animals in the gadodiamide group but none of the animals in other groups showed macroscopic and histological nephrogenic systemic fibrosis-like skin lesions. The Gd concentrations observed in the skin/brain samples (in nanomole Gd per gram of tissue) for each agent were as follows: gadodiamide: 1472 ± 115/11.1 ± 5.1, gadopentetate dimeglumine: 80.8 ± 6.2/13.1 ± 7.3, gadobutrol: 1.1 ± 0.5/0.7 ± 0.4, and gadoteridol: 1.7 ± 0.8/0.5 ± 0.2. The average detected residual Gd concentration in the brain was approximately 15-fold higher for linear than for macrocyclic GBCAs. The highest amounts of Gd found in brain corresponded to less than 0.0002% of the injected dose per gram of tissue. Using LA-ICP-MS, high Gd concentrations in the deep cerebellar nuclei and in the granular layer of the cerebellar cortex were detected only for linear gadodiamide and gadopentetate dimeglumine but not for gadoteridol or gadobutrol. The energy dispersive x-ray spectroscopy analysis revealed Gd-containing spots in the skin of animals administered gadodiamide and gadopentetate dimeglumine. Transmission electron microscopy revealed several Gd-containing spots in the region of the dentate nuclei in the brain of 1 animal injected with gadodiamide. After repeated high dosing, nephrogenic systemic fibrosis-like macroscopic and histopathological lesions of the skin were observed only in some of the gadodiamide-treated animals. No histopathological findings were detected in the rodent brain. The administration of linear GBCAs was associated with significantly higher Gd concentrations in the brain and skin compared with macrocyclic GBCA administration. The results of LA-ICP-MS demonstrated local accumulation of Gd within the deep cerebellar nuclei and the granular layer only after the administration of linear agents. In summary, the detected low Gd concentrations in the skin and brain were well correlated with the higher kinetic stability of macrocyclic GBCA.