The use of cluster and discriminant analysis in the investigations of the role of trace metals in the pathogenesis of Parkinson's disease

Rapid diagnosis of malaria by chemometric peak-free LIBS of trace biometals in blood

Laser Induced Breakdown Spectroscopy (LIBS) trace atomic species of diseased biofluids are subtle (peak-free) in complex spectra. Trace analysis requires a considerable push in analytical strategy. Enabling LIBS with chemometrics can help identify, extract, analyze and interpret the trace species' spectral signatures to give an insight on the biophysiological status of the bodies from which the biofluids originate. We report on the trace quantitative performance of peak-free LIBS enabled by chemometrics modelling using principal components analysis (PCA) for direct artificial neural network (ANN)-based analysis of Cu, Zn, Fe and Mg in Plasmodium falciparum-infected blood in the context of rapid spectral diagnosis of malaria utilizing the biometals as the disease biomarkers. Only one standard is required in this method-to delineate the analyte spectral regions (feature selection) and to test for accuracy. Based on the alteration of the biometal levels and their multivariate and correlational patterns in cultured blood, peripheral finger blood drops dried directly on Nucleopore membrane filters was accurately discriminated as either malaria-infected or healthy. Further the morphological evolution of Plasmodium was accurately predicted using spectral features of the biometals wherein high negative correlations between Fe (- 0.775) and Zn (- 0.881) and high positive correlations between Cu (0.892) and Mg (0.805) with parasitemia were observed. During the first 96 h of malaria infection Cu increases profoundly (from 328 to 1999 ppb) while Fe, Zn and Mg decrease (from 1206 to 674 ppb), (from 1523 to 499 ppb) and (from 23,880 to 19,573 ppb) respectively. Compared with healthy, Plasmodium falciparum-infected blood has high Cu but low levels of Fe, Zn and Mg. Cu and Zn are highly (≥ 0.9) positively correlated while Fe and Cu as well as Zn and Cu are highly (≥ 0.9) negatively correlated. Chemometric peak-free LIBS showed the potential for direct rapid malaria diagnostics in blood based on the levels, alterations and multivariate associations of the trace biometals which are used as biomarkers of the disease.

A review of the “metallome” within neurons and glia, as revealed by elemental mapping of brain tissue

It is now well established that transition metals, such as Iron (Fe), Copper (Cu), and Zinc (Zn) are necessary for healthy brain function. Although Fe, Cu, and Zn are essential to the brain, imbalances in the amount, distribution, or chemical form ("metallome") of these metals is linked to the pathology of numerous brain diseases or disorders. Despite the known importance of metal ions for both brain health and disease, the metallome that exists within specific types of brain cells is yet to be fully characterised. The aim of this mini-review is to present an overview of the current knowledge of the metallome found within specific brain cells (oligodendrocytes, astrocytes, microglia, and neurons), as revealed by direct elemental mapping techniques. It is hoped this review will foster continued research using direct elemental mapping techniques to fully characterise the brain cell metallome.

Perinatal and early-life cobalt exposure impairs essential metal metabolism in immature ICR mice

The objective of the present study was to assess the impact of cobalt (Co) exposure on tissue distribution of iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn), as well as serum hepcidin levels in immature mice (18, 25, 30 days). Pregnant mice were exposed to 75 mg/kg b.w. cobalt chloride (CoCl₂ × 6H2O) with drinking water starting from 3 days before delivery and during lactation. At weaning (day 25) the offspring were separated and housed in individual cages with subsequent exposure to 75 mg/kg b.w. CoCl₂ until 30 days postnatally. Evaluation of tissue metal levels was performed by an inductively coupled plasma-mass spectrometry (ICP-MS). Serum hepcidin level was assayed by enzyme linked immunosorbent assay (ELISA). Cobalt exposure resulted in a time- and tissue-dependent increase in Co levels in kidney, spleen, liver, muscle, erythrocytes, and serum on days 18, 25, and 30. In parallel with increasing Co levels, CoCl₂ exposure resulted in a significant accumulation of Cu, Fe, Mn, and Zn in the studied tissues, with the effect being most pronounced in 25-day-old mice. Cobalt exposure significantly increased serum hepcidin levels only in day18 mice. The obtained data demonstrate that Co exposure may alter essential metal metabolism in vivo.

Organ Metallome Processed with Chemometric Methods Enable the Determination of Elements that May Serve as Markers of Exposure to Iron Oxide Nanoparticles in Male Rats

The systemic influence of iron oxide nanoparticles on the elemental homeostasis of key organs was examined in male rats. In tissues taken at different intervals from nanoparticles injection, the dynamics of elemental changes was analyzed. The organ metallome was studied using total reflection X-ray fluorescence. The obtained data were processed with advanced cluster and discriminant analyses-to classify the tissues according to their organs of origin and to distinguish accurately the nanoparticle-treated and normal rats. Additionally, in the case of liver and heart, it was possible to determine the elements of highest significance for different treatments, which may serve as markers of exposure to iron oxide nanoparticles.

Elemental changes of hippocampal formation occurring during postnatal brain development

In this paper the elemental changes of rat hippocampal formation occurring during the postnatal development were examined. Three groups of animals were used in the study. These were naive Wistar rats at the age of 6-, 30- and 60-days and the chosen life periods corresponded to the neonatal period, childhood and early adulthood in humans, respectively. For the topographic and quantitative elemental analysis X-ray fluorescence microscopy was applied and the measurements were done at the FLUO beamline of ANKA. The detailed quantitative and statistical analysis was done for four areas of hippocampal formation, namely sectors 1 and 3 of the Ammon's horn (CA1 and CA3, respectively), dentate gyrus (DG) and its internal area (hilus of DG, H). The obtained results showed that among the all examined elements (P, S, K, Ca, Fe, Cu, Zn and Se), only the levels of Fe and Zn changed significantly during postnatal development of the hippocampal formation and both the elements were significantly higher in young adults comparing to the rats in neonatal period. The increased Fe areal density was found in all examined hippocampal areas whilst Zn was elevated in CA3, DG and H. In order to follow the dynamics of age-dependent elemental changes, the statistical significance of differences in their accumulation between subsequent moments of time was examined. The obtained results showed statistically relevant increase of Zn level only in the first observation period (between 6th and 30th day of life). Afterwards the areal density of the element did not change significantly. The increase of Fe areal density took place in both examined periods, however the observed changes were small and usually not statistically relevant.

Structural and elemental changes in glioblastoma cells in situ: complementary imaging with high resolution visible light- and X-ray microscopy

The glioblastoma (GBM) is characterized by a short median survival and an almost 100% tumor related mortality. GBM cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores application of X-ray and visible light microscopy to display the elemental and structural images of cells from 3 patient derived GMB samples and an established GMB cell line. Slight differences in elemental concentrations, in actin cytoskeleton organization and cell morphology were noted between all cells types by X-ray fluorescence and full field soft X-ray microscopy, as well as the Structured Illumination Super-resolution Microscope (SIM). Different sample preparation approaches were used to match each imaging technique. While preparation for SIM included cell fixation and staining, intact frozen hydrated cells were used for the trace element imaging by hard X-ray fluorescence and exploration of the structural features by soft X-ray absorption tomography. Each technique documented differences between samples with regard to morphology and elemental composition and underscored the importance of use of multiple patient derived samples for detailed GBM study.

Monte Carlo simulations of elemental imaging using the neutron-associated particle technique

PURPOSE

The purpose of this study is to develop and employ a Monte Carlo (MC) simulation model of associated particle neutron elemental imaging (APNEI) in order to determine the three-dimensional (3D) imaging resolution of such a system by examining relevant physical and technological parameters and to thereby begin to explore the range of clinical applicability of APNEI to fields such as medical diagnostics, intervention, and etiological research.

METHODS

The presented APNEI model was defined in MCNP by a Gaussian-distributed and isotropic surface source emitting deuterium + deuterium (DD) neutrons, iron as the target element, nine iron-containing voxels (1 cm³ volume each) arranged in a 3-by-3 array as the interrogated volume of interest, and finally, by high-purity germanium (HPGe) gamma-ray detectors anterior and posterior to the 9-voxel array. The MCNP f8 pulse height tally was employed in conjunction with the PTRAC particle tracking function to not only determine the signal acquired from iron inelastic scatter gamma-rays but also to quantitate each of the nine target voxels' contribution to the overall iron signal - each detected iron inelastic scatter gamma-ray being traced to the source neutron which incited its emission.

RESULTS

With the spatial, vector, and timing information of the series of events for each relevant neutron history as collected by PTRAC, realistic grayscale images of the distribution of iron concentration in the 9-voxel array were simulated in both the projective and depth dimensions. With an overall 225 ps timing resolution, 6.25 mm² imaging plate pixels assumed to have well localized scintillation, and a DD neutron, Gaussian-distributed source spot with a diameter of 2 mm, projective and depth resolutions of < 1 cm and <3 cm are achievable, respectively, for iron-containing voxels on the order of 1,000 ppm Fe.

CONCLUSIONS

The imaging resolution offered by APNEI of target elements such as iron lends itself to potential applications in disease diagnosis and treatment planning (high resolution) as well as to ordnance and contraband detection (low resolution). However, experimental study beyond simulation is required to optimize the layout and electronic configuration of APNEI system components - including realistic shielding and phantom materials - for background signal reduction in order to accurately determine the detection limits and spatial resolution of iron and other elements of interest on a case-by-case basis.

Practical review on the use of synchrotron based micro- and nano- X-ray fluorescence mapping and X-ray absorption spectroscopy to investigate the interactions between plants and engineered nanomaterials

The increased use of engineered nanomaterials (ENMs) in commercial products and the continuous development of novel applications, is leading to increased intentional and unintentional release of ENMs into the environment with potential negative impacts. Particularly, the partition of nanoparticles (NPs) to waste water treatment plant (WWTP) sludge represents a potential threat to agricultural ecosystems where these biosolids are being applied as fertilizers. Moreover, several applications of ENMs in agriculture and soil remediation are suggested. Therefore, detailed risk assessment should be done to evaluate possible secondary negative impacts. The impact of ENMS on plants as central component of ecosystems and worldwide food supply is of primary relevance. Understanding the fate and physical and chemical modifications of NPs in plants and their possible transfer into food chains requires specialized analytical techniques. Due to the importance of both chemical and physical factors to consider for a better understanding of ENMs behavior in complex matrices, these materials can be considered a new type of analyte. An ideal technique should require minimal sample preparation, be non-destructive, and offer the best balance between sensitivity, chemical specificity, and spatial resolution. Synchrotron radiation (SR) techniques are particularly adapted to investigate localization and speciation of ENMs in plants. SR X-ray fluorescence mapping (SR-XFM) offers multi-elemental detection with lateral resolution down to the tens of nm, in combination with spatially resolved X-ray absorption spectroscopy (XAS) speciation. This review will focus on important methodological aspects regarding sample preparation, data acquisition and data analysis of SR-XFM/XAS to investigate interactions between plants and ENMs.

Essential and Toxic Metals in Oral Fluid-a Potential Role in the Diagnosis of Periodontal Diseases

Recently, many studies have investigated the relationship between the level of metals in the body and various diseases. The objective of this study was to examine any possible influence of periodontal disease upon the concentration of metals in oral fluid and blood and to explore the usability of applying cluster analysis coupled with the analysis of selected elements in oral fluid, calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), zinc (Zn), cadmium (Cd) and lead (Pb), for effectively distinguishing people affected by periodontitis from healthy individuals. The quantification of eight metals in oral fluid and blood samples was performed by two inductively coupled plasma techniques-inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). Most of the examined elements were detected at elevated concentration in the oral fluid of periodontal patients. However, the differences were statistically significant in the case of three metals: Cu, Mg and Mn (p < 0.05). Approximately, fivefold increase in the concentration of Cu, threefold-elevated levels of Mn and a twofold increase in the concentration of Mg were found in the oral fluid of the periodontal patients compared to the controls. Cluster analysis confirmed the statistical significance of the differences in the level of metals in the oral fluid between the two groups in most cases, plus enabled the correct classification of the subjects into patients and controls. The relationship between concentrations of metals and periodontal disease may in the future serve to prevent the development of such disease.

Seasonal variations of particle-associated nitrosamines by gas chromatography-mass spectrometry in the atmospheric environment of Zonguldak, Turkey

A gas chromatography-mass spectrometry method has been proposed for the determination of low-level mutagenic and carcinogenic nitrosamines in particulate matter. The method includes the collection of particulate matters (PM2.5 and PM10) using a dichotomous Partisol 2025 sampler and extraction of the compounds from aqueous solution with dichloromethane/2-propanol after sonication with a slightly basic water solution prior to their GC-MS analysis in electron impact mode. The obtained recoveries of nitrosamines ranged from 92.4 to 99.2 %, and the precision of this method, as indicated by the relative standard deviations, was within the range of 0.95-2.46 %. The detection limits obtained from calculations using the GC-MS results based on S/N=3 were found within the range from 4 to 22 pg/m(3). The predominant nitrosamines determined in particulate matter were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine and N-nitrosomorpholine. Furthermore, N-mono- and dinitrosopiperazine and N-nitrosoethylbutylamine were also determined. N-dinitrosopiperazine was detected in PM2.5 samples at the highest concentrations of up to 22.85 ng/m(3) and in PM2.5-10 samples at concentrations up to 7.60 ng/m(3) in winter, whereas it was found in PM2.5 samples up to 5.15 ng/m(3) and in PM2.5-10 samples up to 3.12 ng/m(3) in summer. The total concentrations of nitrosamines were up to 161.4 ng/m(3) in fine and 53.90 ng/m(3) in coarse fractions in winter, whereas in summer were up to 35.24 and 12.60 ng/m(3), respectively. The concentration levels of nitrosamines fluctuated significantly within a year, with higher means and peak concentrations in the winter compared to that in the summertime. The seasonal variations of particle-associated nitrosamine concentrations were investigated together with their relationships with meteorological parameters using Pearson's correlation analysis in the winter and summer periods. Analysis of variance was used to determine which concentrations of nitrosamines were statistically different from one another and, together with meteorological parameters and discriminant analysis, was used to classify the particle samples by particle size according to seasons. The classification results of the particle samples in different seasons were very satisfactory, allowing 99.5 % of cases to be correctly grouped.

A cell-permeable gadolinium contrast agent for magnetic resonance imaging of copper in a Menkes disease model

We present the synthesis and characterization of octaarginine-conjugated Copper-Gad-2 (Arg₈CG2), a new copper-responsive magnetic resonance imaging (MRI) contrast agent that combines a Gd³⁺-DO3A scaffold with a thioether-rich receptor for copper recognition. The inclusion of a polyarginine appendage leads to a marked increase in cellular uptake compared to previously reported MRI-based copper sensors of the CG family. Arg₈CG2 exhibits a 220% increase in relaxivity (r₁ = 3.9 to 12.5 mM^-1 s^-1) upon 1 : 1 binding with Cu⁺, with a highly selective response to Cu⁺ over other biologically relevant metal ions. Moreover, Arg₈CG2 accumulates in cells at nine-fold greater concentrations than the parent CG2 lacking the polyarginine functionality and is retained well in the cell after washing. In cellulo relaxivity measurements and T₁-weighted phantom images using a Menkes disease model cell line demonstrate the utility of Arg₈CG2 to report on biological perturbations of exchangeable copper pools.

Neoplastic disorders of prostate glands in the light of synchrotron radiation and multivariate statistical analysis

The prostate gland is the most common site of neoplastic disorders in men. The pathogenesis of inflammatory cells, prostatic intraepithelial neoplasia (PIN) lesions, and prostate cancer is still under investigation. Inflammatory cells by producing free radicals are considered as major and universal contributors to cancerogenesis. PIN is regarded as a precursor lesion to prostate cancer or a marker signaling the vulnerability of the epithelium to neoplastic transformation [1]. Differentiation markers that are frequently changed in early invasive carcinoma are also changed in PIN lesions. In this study, prostate tissue samples obtained during surgical operation and classified as various disease states (inflammation, PIN lesions, and cancer) were examined. The samples were measured by means of microbeam synchrotron-radiation-induced X-ray emission (micro-SRIXE). Special attention was paid to examine the relationship between the earlier-mentioned disorders and changes in relative concentrations of S, K, Ca, Fe, Cu, and Zn. Applying the image-processing program ImageJ enabled us to select the areas of interest from two-dimensional maps of various prostate samples according to the histopathologist's evaluation. Detailed analysis of micro-SRIXE spectra based on multivariate methods shows significant differences between elemental concentrations in inflammatory cells, PIN lesions, and cancerous tissues, which confirms that this method can be used to distinguish various pathological states in prostate tissues. Information obtained in this way may provide better understanding of the biochemistry of unhealthy prostate tissues, thus opening the way to find new medicines/treatments to prevent or slow down some harmful intracellular processes.