Ultrasmall cerium oxide nanoparticles as highly sensitive X-ray contrast agents and their antioxidant effect

Owing to their theranostic properties, cerium oxide (CeO2) nanoparticles have attracted considerable attention for their key applications in nanomedicine. In this study, ultrasmall CeO2 nanoparticles (particle diameter = 1-3 nm) as X-ray contrast agents with an antioxidant effect were investigated for the first time. The nanoparticles were coated with hydrophilic and biocompatible poly(acrylic acid) (PAA) and poly(acrylic acid-co-maleic acid) (PAAMA) to ensure satisfactory colloidal stability in aqueous media and low cellular toxicity. The synthesized nanoparticles were characterized using high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, thermogravimetric analysis, dynamic light scattering, cell viability assay, photoluminescence spectroscopy, and X-ray computed tomography (CT). Their potential as X-ray contrast agents was demonstrated by measuring phantom images and in vivo CT images in mice injected intravenously and intraperitoneally. The X-ray attenuation of these nanoparticles was greater than that of the commercial X-ray contrast agent Ultravist and those of larger CeO2 nanoparticles reported previously. In addition, they exhibited an antioxidant effect for the removal of hydrogen peroxide. The results confirmed that the PAA- and PAAMA-coated ultrasmall CeO2 nanoparticles demonstrate potential as highly sensitive radioprotective or theranostic X-ray contrast agents.

Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method. Their physicochemical and X-ray attenuation properties were characterized. All polymer-coated Pt-NPs had an average particle diameter (d_avg) of 2.0 nm. Polymers grafted onto Pt-NP surfaces exhibited excellent colloidal stability (i.e., no precipitation after synthesis for >1.5 years) and low cellular toxicity. The X-ray attenuation power of the polymer-coated Pt-NPs in aqueous media was stronger than that of the commercial iodine contrast agent Ultravist at the same atomic concentration and considerably stronger at the same number density, confirming their potential as computed tomography contrast agents.

Chitosan Oligosaccharide Lactate-Coated Ultrasmall Gadolinium Oxide Nanoparticles: Synthesis, In Vitro Cytotoxicity, and Relaxometric Properties

In this study, hydrophilic and biocompatible chitosan oligosaccharide lactate (COL)-coated ultra-small gadolinium oxide nanoparticles (NPs) were synthesized through a one-pot polyol method and characterized by various experimental techniques. The In Vitro cellular cytotoxicity assay indicated that the COL-coated gadolinium oxide NPs were non-toxic up to 500 μM Gd. In addition, their water proton spin relaxivities (i.e., r₁ and r₂) were estimated to be 13.0 and 27.0 s^-1mM^-1, respectively, which are higher than those of commercial magnetic resonance imaging (MRI) contrast agents. The application potential of the solution sample as a T₁ MRI contrast agent was demonstrated In Vitro by measuring map images in which dose-dependent contrast enhancements were observed.

Synthesis, Characterizations, and 9.4 Tesla T2 MR Images of Polyacrylic Acid-Coated Terbium(III) and Holmium(III) Oxide Nanoparticles

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln2O3) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T2) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r2 values were appreciable at a 3.0 T MR field and higher at a 9.4 T MR field, whereas their r1 values were negligible at all MR fields, indicating their exclusive induction of T2 relaxations with negligible induction of T1 relaxations. Their effectiveness as T2 MRI contrast agents at high MR fields was confirmed from strong negative contrast enhancements in in vivo T2 MR images at a 9.4 T MR field after intravenous administration into mice tails.

Hydrophilic Biocompatible Poly(Acrylic Acid-co-Maleic Acid) Polymer as a Surface-Coating Ligand of Ultrasmall Gd2O3 Nanoparticles to Obtain a High r1 Value and T1 MR Images

The water proton spin relaxivity, colloidal stability, and biocompatibility of nanoparticle-based magnetic resonance imaging (MRI) contrast agents depend on the surface-coating ligands. Here, poly(acrylic acid-co-maleic acid) (PAAMA) (Mw = ~3000 amu) is explored as a surface-coating ligand of ultrasmall gadolinium oxide (Gd2O3) nanoparticles. Owing to the numerous carboxylic groups in PAAMA, which allow its strong conjugation with the nanoparticle surfaces and the attraction of abundant water molecules to the nanoparticles, the synthesized PAAMA-coated ultrasmall Gd2O3 nanoparticles (davg = 1.8 nm and aavg = 9.0 nm) exhibit excellent colloidal stability, extremely low cellular toxicity, and a high longitudinal water proton spin relaxivity (r1) of 40.6 s-1mM-1 (r2/r1 = 1.56, where r2 = transverse water proton spin relaxivity), which is approximately 10 times higher than those of commercial molecular contrast agents. The effectiveness of PAAMA-coated ultrasmall Gd2O3 nanoparticles as a T1 MRI contrast agent is confirmed by the high positive contrast enhancements of the in vivo T1 MR images at the 3.0 T MR field.

New Class of Efficient T2 Magnetic Resonance Imaging Contrast Agent: Carbon-Coated Paramagnetic Dysprosium Oxide Nanoparticles

Nanoparticles are considered potential candidates for a new class of magnetic resonance imaging (MRI) contrast agents. Negative MRI contrast agents require high magnetic moments. However, if nanoparticles can exclusively induce transverse water proton spin relaxation with negligible induction of longitudinal water proton spin relaxation, they may provide negative contrast MR images despite having low magnetic moments, thus acting as an efficient T₂ MRI contrast agent. In this study, carbon-coated paramagnetic dysprosium oxide (DYO@C) nanoparticles (core = DYO = Dy_xO_y; shell = carbon) were synthesized to explore their potential as an efficient T₂ MRI contrast agent at 3.0 T MR field. Since the core DYO nanoparticles have an appreciable (but not high) magnetic moment that arises from fast 4f-electrons of Dy(III) (⁶H_15/2), the DYO@C nanoparticles exhibited an appreciable transverse water proton spin relaxivity (r₂) with a negligible longitudinal water proton spin relaxivity (r₁). Consequently, they acted as a very efficient T₂ MRI contrast agent, as proven from negative contrast enhancements seen in the in vivo T₂ MR images.

D-Glucuronic Acid-Coated Ultrasmall Bi₂O₃ Nanoparticles for CT Imaging

Ultrasmall Bi₂O₃ nanoparticles (d_avg = 1.5 nm) coated with biocompatible and hydrophilic D-glucuronic acid were prepared for the first time through a simple one-step polyol process and their potential as CT contrast agents were investigated by measuring their X-ray attenuation properties. Their observed X-ray attenuation power was stronger than that of a commercial iodine CT contrast agent at the same atomic concentration, as consistent with the magnitudes of atomic X-ray attenuation coefficients (i.e., Bi > I), and much stronger at the same number density. The results indicate that the nanoparticle sample is a potential CT contrast agent.

In Vivo Positive Magnetic Resonance Imaging Applications of Poly(methyl vinyl ether-alt-maleic acid)-coated Ultra-small Paramagnetic Gadolinium Oxide Nanoparticles

The study of ultra-small paramagnetic gadolinium oxide (Gd2O3) nanoparticles (NPs) as in vivo positive (T1) magnetic resonance imaging (MRI) contrast agents is one of the most attractive fields in nanomedicine. The performance of the Gd2O3 NP imaging agents depends on the surface-coating materials. In this study, poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was used as a surface-coating polymer. The PMVEMA-coated paramagnetic ultra-small Gd2O3 NPs with an average particle diameter of 1.9 nm were synthesized using the one-pot polyol method. They exhibited excellent colloidal stability in water and good biocompatibility. They also showed a very high longitudinal water proton spin relaxivity (r1) value of 36.2 s-1mM-1 (r2/r1 = 2.0; r2 = transverse water proton spin relaxivity) under a 3.0 tesla MR field which is approximately 10 times higher than the r1 values of commercial molecular contrast agents. High positive contrast enhancements were observed in in vivo T1 MR images after intravenous administration of the NP solution sample, demonstrating its potential as a T1 MRI contrast agent.

In vivo neutron capture therapy of cancer using ultrasmall gadolinium oxide nanoparticles with cancer-targeting ability

Gadolinium neutron capture therapy (GdNCT) is considered as a new promising cancer therapeutic technique. Nevertheless, limited GdNCT applications have been reported so far. In this study, surface-modified ultrasmall gadolinium oxide nanoparticles (UGNPs) with cancer-targeting ability (d_avg = 1.8 nm) were for the first time applied to the in vivo GdNCT of cancer using nude model mice with cancer, primarily because each nanoparticle can deliver hundreds of Gd to the cancer site. For applications, the UGNPs were grafted with polyacrylic acid (PAA) for biocompatibility and colloidal stability, which was then conjugated with cancer-targeting arginylglycylaspartic acid (RGD) (shortly, RGD-PAA-UGNPs). The solution sample was intravenously administered into the tails of nude model mice with cancer. At the time of the maximum accumulation of the RGD-PAA-UGNPs at the cancer site, which was monitored using magnetic resonance imaging, the thermal neutron beam was locally irradiated onto the cancer site and the cancer growth was monitored for 25 days. The cancer growth suppression was observed due to the GdNCT effects of the RGD-PAA-UGNPs, indicating that the surface-modified UGNPs with cancer-targeting ability are potential materials applicable to the in vivo GdNCT of cancer.

A cancer growth suppression was observed due to the GdNCT effects of the RGD-PAA-UGNPs.

Relaxometric, Optical and Cell Viability Properties of D-Glucuronic Acid Coated Cr₂O₃ Nanoparticles

D-glucuronic acid-coated ultrasmall chromium oxide (Cr2O3) nanoparticles were synthesized by a one-pot polyol method and their relaxometric and optical properties were investigated. The as-synthesized D-glucuronic acid-coated nanoparticles were amorphous owing to ultrasmall particle diameters (davg = 2.0 nm), whereas orthorhombic Cr2O3 nanoparticles with two size groups (davg = 3.6 and 5.7 nm) were observed after thermogravimetric analysis (900 °C) as a result of particle growth. The nanoparticles exhibited size-dependent UV-visible absorption maxima at 238, 274, and 372 nm with increasing particle diameter, corresponding to band gaps of 5.13, 4.45, and 3.28 eV, respectively. D-glucuronic acid-coated ultrasmall Cr2O3 nanoparticles revealed low water proton relaxivities of r1 = 0.05 s-1mM-1 and r2 = 0.20 s-1mM-1, consistent with the antiferromagnetic property of Cr2O3. They showed good biocompatibility up to 500 μM of Cr.

Stable and non-toxic ultrasmall gadolinium oxide nanoparticle colloids (coating material = polyacrylic acid) as high-performance T1 magnetic resonance imaging contrast agents

For use as positive (T₁) magnetic resonance imaging contrast agents (MRI-CAs), gadolinium oxide (Gd₂O₃) nanoparticle colloids (i.e. nanoparticles coated with hydrophilic ligands) should be stable, non-toxic, and ultrasmall in particle diameter for renal excretion. In addition, they should have a high longitudinal water proton relaxivity (r₁) and r₂/r₁ ratio that is close to one (r₂ = transverse water proton relaxivity) for high-performance. In this study, we report ultrasmall Gd₂O₃ nanoparticle colloids [coating material = polyacrylic acid, M_w = ∼5100 Da] satisfying these conditions. The particle diameter was monodisperse with an average value of 2.0 ± 0.1 nm. The colloidal suspension exhibited a high r₁ value of 31.0 ± 0.1 s⁻¹ mM⁻¹ and r₂/r₁ ratio of 1.2, where r₁ was ∼8 times higher than that of commercial Gd-chelates: the cooperative induction model was proposed to explain this. The effectiveness of the colloidal suspension as a high-performance T₁ MRI-CA was confirmed by taking in vivo T₁ MR images in a mouse after intravenous administration. Highly positive contrast enhancements were observed in various organs of the mouse such as the liver, kidneys, and bladder. The colloidal suspension was then excreted through the bladder.

Stable and non-toxic ultrasmall Gd₂O₃ nanoparticle colloids as high-performance T₁ MRI-CA were developed.

The Effects of Recreation Therapy on the Habit of Smoking and Positive–Negative Symptoms Among Patients with Chronic Schizophrenia

Schizophrenia is a psychiatric condition that has detrimental outcomes on an individual’s thinking, understanding and feelings. However, it not only affects one’s actions and emotions, but also, and quite specifically, creates an avenue for such antisocial behavior as seclusion. Hence, it is important to highlight the necessary requirements for the recovery of schizophrenic patients and subsequently delve deeper into the signs and symptoms of schizophrenia itself, especially among patients who have been confined to psychiatric care for too long. The aim of this study was to determine the effects of recreation therapy on smoking as well as the positive-negative symptoms of schizophrenia among patients who have reached the chronic stage of this condition. Essentially, this was a semi-experimental study with one pretest and one posttest. 50 patients under psychiatric care, aged between 30 to 50 years, were selected and then equally divided into the control and experimental groups. The instruments for this research were the Anderson questionnaire and the smoking cigarette questionnaire, the latter being created by the researcher. Data were analyzed using descriptive and inferential statistics. To evaluate the hypothesis of research, this study relied on a covariance analysis. Based on the results, it can be said that there were significant (p ≤ 0.05) differences between the control and experimental groups related to smoking as well as the positive-negative symptoms of schizophrenia. It shows that 4 months of recreation therapy was able to decrease the prevalence of smoking (19.9%), in addition to the positive symptoms (18.3%) and negative symptoms (14.7%) of schizophrenia within the experimental group. It is hoped that the results of this study will encourage the use of recreation therapy as a practical and non-pharmacological form of treatment for patients with chronic schizophrenia.

Cardiac fiber rotation distorts surface measurements of anisotropic propagation

Anisotropy is often determined experimentally from epicardial propagation measurements. We hypothesize that the direction of wave propagation on the epicardial surface is not aligned with the epicardial fiber orientation, due to intramural fiber rotation. In this paper, we modeled the effect of cardiac tissue fiber rotation on wave propagation. We used a three dimensional computer model of varying thickness with a 120 degree fiber rotation through the thickness. The angle difference between the direction of propagation and fiber orientation was most pronounced for thin tissue, and decreased with increasing tissue thickness. This angle also increased with the time elapsed since stimulation. Finally, we demonstrated that the fiber rotation from epicardium to endocardium results in inaccurate measurements of conduction velocities at the epicardium, particularly in thin tissues.

Application of a multi-structure neural network (MSNN) to sorting pistachio nuts

A multi-structure neural network (MSNN) classifier consisting of four discriminators followed by a maximum selector was designed and applied to classification of four grades of pistachio nuts. Each discriminator was a multi-layer feed-forward neural network with two hidden layers and a single-neuron output layer. Fourier descriptors of the nuts' boundaries and their area were used as the recognition features. The individual discriminators were trained using a biased technique and a back-propagation algorithm. The MSNN classifier gave an average classification performance of 95.0%. This was an increase of 14.8% over the performance of a multi-layer neural network (MLNN) with similar complexity for classifying the same set of patterns.

Transketolase abnormality in cultured fibroblasts from familial chronic alcoholic men and their male offspring

We have investigated a thiamine-dependent enzyme, transketolase, in cultured fibroblasts from 41 human subjects, including patients with alcoholism-associated Wernicke-Korsakoff syndrome (n = 3), familial chronic alcoholic males (n = 7), their sons (n = 7), nonalcoholic men (n = 7), their male offspring (n = 7), and three generations of an Amish family (n = 10) without any history of alcoholism. This study was undertaken to delineate whether transketolase abnormality (i.e., high Michaelis Menton constant (Km) for thiamine pyrophosphate), previously reported in patients with Wernicke-Korsakoff syndrome is prevalent among familial chronic alcoholic men and their sons without prior history of alcohol abuse but who are at high risk for alcoholism. Our data suggest that an inborn error (i.e., high Km of transketolase for thiamine pyrophosphate) predisposing to thiamine deficiency diseases similar to those reported in Wernicke-Korsakoff syndrome may occur in the general population. However, for some as yet unexplained reason(s) this variant seems to occur more frequently among familial chronic alcoholic men and their male offspring without any history of alcoholism. The inheritance pattern of this enzyme variant as revealed from an Amish pedigree study may be autosomal recessive as previously suggested.

Transketolase abnormality in tolazamide-induced Wernicke's encephalopathy

We studied a thiamine-dependent enzyme, transketolase, from fibroblasts of a diabetic patient who developed Wernicke's encephalopathy when treated with tolazamide, in order to delineate if this patient also had transketolase abnormality [high Km for thiamine pyrophosphate (TPP)], as previously reported in postalcoholic Wernicke-Korsakoff syndrome. In addition to this patient, we also studied this enzyme from three diabetic kindreds without any history of Wernicke's encephalopathy and from four normal controls. We found that the above-mentioned patient and one of the diabetic kindreds with no history of Wernicke's encephalopathy had abnormal transketolase as determined by its Km for TPP. These data suggest a similarity between postalcoholic Wernicke-Korsakoff syndrome and the patient with tolazamide-induced Wernicke's encephalopathy from the standpoint of transketolase abnormality.