Hierarchical clustering of Alzheimer and “normal” brains using elemental concentrations and glucose metabolism determined by PIXE, INAA and PET

Brain tissue samples, obtained from the Alzheimer Disease Brain Bank,Institute of Psychiatry, London, were taken from both left and right hemispheresof three regions of the cerebrum, namely the frontal, parietal and occipitallobes for both Alzheimer and 'normal' subjects. Trace elementconcentrations in the frontal lobe were determined for twenty six Alzheimer(15 male, 11 female) and twenty six 'normal' (8 male, 18 female)brain tissue samples. In the parietal lobe ten Alzheimer (2 male, 8 female)and ten 'normal' (8 male, 2 female) samples were taken along withten Alzheimer (4 male, 6 female) and ten 'normal' (6 male, 4 female)from the occipital lobe. For the frontal lobe trace element concentrationswere determined using proton induced X-ray emission (PIXE) analysis whilein parietal and occipital regions instrumental neutron activation analysis(INAA) was used. Additionally eighteen Alzheimer (9 male, 9 female) and eighteenage matched 'normal' (8 male, 10 female) living subjects wereexamined using positron emission tomography (PET) in order to determine regionalcerebral metabolic rates of glucose (rCMRGlu). The rCMRGlu of 36 regions ofthe brain was investigated including frontal, occipital and parietal lobesas in the trace element study. Hierarchical cluster analysis was applied tothe trace element and glucose metabolism data to discover which variablesin the resulting dendrograms displayed the most significant separation betweenAlzheimer and 'normal' subjects.     

Assessment of metal and trace element concentrations in the Cananéia estuary,Brazil, by neutron activation and atomic absorption techniques

Twenty six bottom sediment samples were collected from the Cananéia estuary in summer and winter of 2005. Multielemental analysis was carried out by instrumental neutron activation analysis. Total mercury was determined by cold vapor atomic absorption. As, Cr, Hg and Zn concentrations were compared to the Canadian oriented values (TEL and PEL). Sample points 4 and 9 presented higher concentration for most elements and As and Cr exceeded the TEL values. Organic matter (>10%) associated with siltic and clay sediments was observed. Climatic conditions, hydrodynamic and biogeochemical processes promote differences in seasonal concentrations of elements at some points, which contribute to special distributions.     

Elemental analysis of the frontal lobe of “normal” brain tissue and that affected by Alzheimer's disease

Normal brain tissue and brain tissue affected by Alzheimer's disease has been taken from the frontal lobe of both hemispheres and their elemental compositions in terms of major, minor and trace elements compared. Brain samples were obtained from the MRC Alzheimer's Disease Brain Bank, London. 25 samples were taken from 18 individuals (5 males and 13 females) of mean age 79.9±7.3 years with pathologically confirmed Alzheimer'sdisease and 26 samples from 15 individuals (8 males and 7 females) of mean age 71.8±13.0 years with no pathological signs of Alzheimer's disease (normals). The elemental concentration of the samples were determined by the techniques of Rutherford backscattering (RBS) analysis, particle induced X-ray emission (PIXE) analysis and instrumental neutron activation analysis (INAA). Na, Mg, Al, Cl, K, Sc, Fe, Zn, Se, Br, Rb and Cs were detected by INAA and significant differences in concentrations were found between concentrations in normal and Alzheimer tissue for the elements. Na, Cl, K, Se, Br and Rb, P, S, Cl, K, Ca, Fe, Zn and Cd were detected by PIXE analysis and significant differences found for the elements P, S, Cl, K and Ca.     

Radiochemical neutron activation analysis of chromium in biological materials using ion chromatography with “on-line” yield determination

The use of ion chromatography with continuous UV detection for radiochemical separation of Cr with simultaneous yield determination is presented. The RNAA method consists of sample destruction in HNO₃+HClO₄, extraction of Cr(VI) with tribenzylamine in CHCl₃, backextraction in NaOH and chromatography of chromate. From radiotracer experiments, the ratio of signals for⁵¹Cr and Cr spike was found to be constant for a chromium mass range of 15 to 100 g. Application of the RNAA method to Cr determination in biological reference materials showed a reasonable agreement with the reference values. A relative standard deviation of 3% on the 100 g/kg level for homogeneous material was achieved.IAEA-fellow, on leave from the Philippine Nuclear Research Institute Philippine     

The program “MULTINAA” for various standardization methods in neutron activation analysis

A compute program MULTINAA was developed to facilitate the evaluation of NAA data. It is written for the VAX/VMS syste and opeates in the Canberra/ND Genie spectroscopy software environment. MULTIINAA can be appliede to relative,k ₀-, monostandard (modified) and absolute methods, including the fast neutron threshold reaction. For each calculation, the available standardizations can be used individually or mixed. In all the standardization modes MULTINAA fetches the data directly from the -ray spectra and libraries, thus reducing the manual work to a minimum. MULTINAA is flexibkle to meet various situations in NAA practical work. The required neutron flux parameters all the non-relative methods are supplied by an accompanying program MULTIFLUX.     

Non-destructive compositional analysis of sol–gel synthesized lithium titanate (Li2TiO3) by particle induced gamma-ray emission and instrumental neutron activation analysis

Lithium titanate, one of the important tritium breeding materials in D–T based fusion reactor under ITER programme, was synthesized through sol–gel route. For chemical quality control of finished product, it was necessary to quantify the lithium and titanium contents. As this ceramic sample is difficult to dissolve, non-destructive analytical methods are preferred for compositional analysis. In the present work, two non-destructive nuclear analytical methods namely particle induced gamma-ray emission (PIGE) using proton beam and instrumental neutron activation analysis (INAA) using reactor neutrons were standardized for the determination of lithium and titanium concentrations, respectively and applied to eleven samples of lithium titanate. To the best of our knowledge, Li quantification in lithium titanate sample is being reported for the first time using PIGE. For quantifications of Li and Ti, 478 keV prompt gamma-ray from ⁷Li (p, p′γ) ⁷Li and 320 keV gamma-ray from ⁵⁰Ti (n,γ) ⁵¹Ti were measured, respectively, by high resolution gamma-ray spectrometry. The PIGE and INAA methods were validated using several synthetic samples containing lithium and titanium, respectively. Concentrations of lithium and titanium and Li/Ti mole ratios were evaluated and compared with the stoichiometric concentration of Li₂TiO₃.     

Isoprenoid quantitation in human brain tissue: a validated HPLC–fluorescence detection method for endogenous farnesyl- (FPP) and geranylgeranylpyrophosphate (GGPP)

Farnesyl- and geranylgeranylpyrophosphate (FPP and GGPP) are isoprenoid intermediates in the mevalonate pathway. They play a crucial role in cell survival, growth and differentiation due to their attachment (isoprenylation) to small GTPases (Ras, Rho, etc.). Isoprenoid formation seems to be tightly regulated within the mevalonate pathway and its perturbation has been linked to certain diseases (e.g., cancer, Alzheimer's disease), but tissue levels are unknown. It is therefore of the utmost importance to quantify these isoprenoids in diseased tissue or in tissue after drug administration. The current work describes an isolation procedure utilizing a combination of Extrelut(R) liquid/liquid and reversed-phase solid-phase extraction (SPE) for homogenized human frontal cortex tissue. In addition, after a careful validation of an HPLC-fluorescence method, this assay allowed the determination of nanomolar concentrations of endogenous FPP and GGPP levels (4.5 and 10.6 ng/mg protein, respectively) in human brain tissue. The method is selective, precise (<15% RSD), accurate (<15% relative error) and sensitive over a linear range of 10-400 ng/mL for FPP and 50-1000 ng/mL for GGPP according to the current FDA criteria for bioanalytical method validation. Overall, this new method introduces the ability to simultaneously quantify FPP and GGPP in human brain tissue, and is potentially applicable to several other tissues and species.     

Fluorine determination in biological and environmental samples with INAA using fast neutrons from a p(19 MeV) + Be neutron generator

Journal of Radioanalytical and Nuclear Chemistry - We present a new activation method based on the 19F(n,2n)18F reaction using fast neutrons produced by a p(19&nbsp;MeV)?+?Be...     

Uptake of oxygen in a coal standard reference material® determined by fast (14-MeV) neutron activation analysis

A fast (14-MeV) neutron activation analysis procedure was employed to directly measure mass fractions of oxygen in coal samples. The procedure demonstrated sufficient precision and accuracy to determine a relative change of about 5% or more, in the oxygen mass fraction of about 12%. The procedure was applied to test samples of the newly developed SRM 1632c Trace Elements in Coal (Bituminous). The samples had been stored at three conditions: in liquid nitrogen vapor and at room temperature in the original containers packaged under argon, and for accelerated aging at 50 °C open to air. Following six months storage increments, duplicate samples of each of twelve bottles of the SRM were measured for each storage condition. In addition each sample was processed through ten separate analytical runs yielding a total of some 720 measurements per storage duration. Oxygen was determined by comparison to a primary standard potassium dichromate and the accuracy of the method was assessed through the analysis of replicate samples of three reference materials that are certified for oxygen content. The initial 6-months test period indicated uptake of oxygen in the open-air storage.     

Reversed-phase extraction chromatography–neutron activation analysis (RPEC–NAA) for copper in natural waters using Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol

A preconcentration neutron activation analysis method has been developed for the determination of trace levels of Cu in natural waters including seawater with an absolute detection limit of 0.106 μg. The method involves the preconcentration of Cu onto Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol using reversed-phase extraction chromatography (RPEC). Copper is assayed through its neutron activation product ⁶⁶Cu (half-life = 5.10 min) by direct irradiation of the resin bed. Factors affecting the uptake of Cu onto the ligand-impregnated resin have been investigated; these include flow rate, pH, column height, presence of other trace elements, major elements, and interfering matrix. The RPEC–NAA method has been validated by analyzing NIST and NRC water reference materials.     

A rapid and sensitive assay for determining human brain levels of farnesyl-(FPP) and geranylgeranylpyrophosphate (GGPP) and transferase activities using UHPLC–MS/MS

The isoprenoids farnesyl-(FPP) and geranylgeranylpyrophosphate (FPP and GGPP) are two major lipid intermediates in the mevalonate pathway. They participate in post-translational modification of members of the superfamily of small guanosine triphosphatases (GTPases; Ras, Rab, Rac, etc.) via prenylation reactions. Due to the important role of these proteins in a number of cell processes, in particular cell growth, division, and differentiation, investigation of the involvement of isoprenoids in these processes is of great interest. In a previously published report, we described a fully validated assay for the quantitation of the two isoprenoids using a high-performance liquid chromatography (HPLC)–fluorescence detection (FLD) method. The current work expands on the previous method and enhances it greatly by using a much faster state-of-the-art ultrahigh-performance liquid chromatography (UHPLC) technique coupled to tandem mass spectrometry (MS/MS). The method exhibited a linear concentration range of 5–250 ng/mL for FPP and GGPP in human brain tissue; it was shown to be unaffected by ion suppression and provided results almost six times faster than the HPLC–FLD assay. Comparison of UHPLC–MS/MS and HPLC–FLD yielded excellent comparability of the two assays for both isoprenoids. Based on the UHPLC–MS/MS assay, a novel in vitro test system was implemented to study enzyme specificity for distinct amino acid CAAX motifs, which is potentially useful for investigating target interactions of new therapeutics for diseases involving pathological regulation of isoprenoids and/or small GTPases.     

Quantification of Paraquat, MPTP, and MPP+ in brain tissue using microwave-assisted solvent extraction (MASE) and high-performance liquid chromatography–mass spectrometry

Animal models, consistent with the hypothesis of direct interaction of paraquat (PQ) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) with specific areas of the central nervous system have been developed to study Parkinson’s disease (PD) in mice. These models have necessitated the creation of an analytical method for unambiguous identification and quantitation of PQ and structurally similar MPTP and 1-methyl-4-phenylpyridinium ion (MPP⁺) in brain tissue. A method for determination of these compounds was developed using microwave-assisted solvent extraction (MASE) and liquid chromatography–mass spectrometry. Extraction solvent and microwave conditions such as power and time were optimized to produce recoveries of 90% for PQ 78% for MPTP and 97% for its metabolite MPP⁺. The chromatographic separation was performed on a C8, column and detection was carried out using an ion trap as an analyzer with electrospray ionization. Mass spectrometer parameters such as heated capillary temperature, spray voltage, capillary voltage and others were also optimized for each analyte. Analysis was done in selective ion-monitoring (SIM) mode using m/z 186 for PQ, m/z 174 for MPTP, and m/z 170 for MPP⁺. The method detection limit for paraquat in matrix was 100 pg, 40 pg for MPTP, and 20 pg MPP⁺.     

Correction to: Active biomonitoring of atmospheric pollution in the Western Cape (South Africa) using INAA and ICP‑MS

Journal of Radioanalytical and Nuclear Chemistry - The article “Active biomonitoring of atmospheric pollution in the Western Cape (South Africa) using INAA and ICP?MS”.     

Improved correlation between animal and human potency of non-steroidal anti-inflammatory drugs using quantitative structure–activity relationships (QSARs)

Animal models are known not to predict human responses well, in general. However, we have been able to demonstrate that, for a series of non-steroidal anti-inflammatory drugs that are or were in clinical use, the incorporation of two simple physicochemical properties results in excellent correlations between human and rodent potencies for anti-inflammatory, analgesic and anti-pyretic activities. This has the potential to allow the use of historical data to improve drug development.     

Major,minor and trace element mass fractions determined using ED-XRF,WD-XRF and INAA for five certified clay reference materials: NCS DC 60102–60105; NCS DC 61101 (GBW 03101A, 03102A, 03103, and 03115)

Major, minor and trace element mass fractions were determined using wavelength dispersive and energy dispersive X-ray fluorescence and instrumental neutron activation analysis for five clay certified reference materials (NCS DC 60102–60105, 61101) distributed by the National Research Center for Certified Reference Materials in China. We report mass fractions for 10 major and the following 29 minor and trace elements: As, Ba, Ce, Co, Cr, Cs, Cu, Eu, Hf, La, Lu, Nb, Nd, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, U, V, Y, Yb, Zn, and Zr.     

Development of a green effervescence-assisted dispersive liquid–liquid microextraction method using a home-made tablet disperser for trace analysis of Cd(II) and Pb(II)

An analytical approach for the determination of trace amounts of Cd(II) and Pb(II) has been developed using a home-made tablet-based effervescence-assisted dispersive liquid–liquid microextraction (DLLME) method which was performed in a narrow-bore tube, followed by flame atomic absorption spectrometry. In this method, a mixture of tartaric acid, sodium bicarbonate and NaCl was used to make the disperser tablet. Then, microlitre level of an extraction solvent was added in the tablet, and then, it was released into a narrow-bore tube containing sample solution and a complexing agent. An acid–base reaction immediately occurred between tartaric acid and sodium bicarbonate, and the produced CO₂ led to the dispersion of the extraction solvent into the solution as tiny droplets and subsequent extraction of the analytes. The method made possible the determination of Cd(II) and Pb(II) in the ranges of 0.1–10 and 1.0–20 µg L^?1, respectively. The limits of detection were obtained 0.43 and 0.05 µg L^?1 for Pb(II) and Cd(II), respectively. The limits of quantifications were 0.80 and 0.09 µg L^?1 for Pb(II) and Cd(II), respectively. Repeatability of the method, which is expressed as relative standard deviation, was obtained 3.1% (n = 6, C = 2 µg L^?1) and 1.3% (n = 6, C = 0.2 µg L^?1) for Pb(II) and Cd(II), respectively. The accuracy of the developed method was verified by analysing a certified reference material, namely SPS-WW2 Batch 108. Relative recoveries (84–107%, obtained at three fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples and fruit juices. The method was shown to be fast, reliable and environmentally friendly with low organic solvent consumption.     

Studies on the metabolism of the α-pyrrolidinophenone designer drug methylenedioxy-pyrovalerone (MDPV) in rat and human urine and human liver microsomes using GC-MS and LC-high-resolution MS and its detectability in urine by GC-MS

Since the late 1990s, many derivatives of the α-pyrrolidinophenone (PPP) drug class appeared on the drugs of abuse market. The latest compound was described in 2009 to be a classic PPP carrying a methylenedioxy moiety remembering the classic entactogens (ecstasy). Besides Germany, 3,4-methylene-dioxypyrovalerone (MDPV) has appeared in many countries in Europe and Asia, indicating its worldwide importance for forensic and clinical toxicology. The aim of the presented work was to identify the phase I and II metabolites of MDPV and the human cytochrome-P450 (CYP) isoenzymes responsible for its main metabolic step(s). Finally, the detectability of MDPV in urine by the authors' systematic toxicological analysis (STA) should be studied. The urine samples were extracted after and without enzymatic cleavage of conjugates. The metabolites were separated and identified after work-up by GC-MS and liquid chromatography (LC)-high-resolution MS (LC-HR-MS). The studies revealed the following phase I main metabolic steps in rat and human: demethylenation followed by methylation, aromatic and side chain hydroxylation and oxidation of the pyrrolidine ring to the corresponding lactam as well as ring opening to the corresponding carboxylic acid. Using LC-HR-MS, most metabolite structures postulated according to GC-MS fragmentation could be confirmed and the phase II metabolites were identified. Finally, the formation of the initial metabolite demethylenyl-MDPV could be confirmed using incubation of human liver microsomes. Using recombinant human CYPs, CYP 2C19, CYP 2D6 and CYP 1A2 were found to catalyze this initial step. Finally, the STA allowed the detection of MDPV metabolites in the human urine samples.     

Correlation between Am(III)/Eu(III) selectivity and covalency in metal–chalcogen bonds using density functional calculations

Journal of Radioanalytical and Nuclear Chemistry - We applied density functional theory calculations to Am(III) and Eu(III) complexes with chalcogen-donor ligands of the formula N(EPMe2) 2 −...