Glutaraldehyde-modified electrode for nonlabeling voltammetric detection of <Emphasis Type="Italic">p16</Emphasis><Superscript><Emphasis Type="Italic">INK4A</Emphasis></Superscript> gene

A nonlabeling electrochemical detection method for analyzing the polymerase-chain-reaction-amplified sequence-specific p16 ^INK4A gene, in which the basis for the covalent immobilization of deoxyribonucleic acid (DNA) probe is described, has been developed. The self-assembly process was based on the covalent coupling of glutaraldehyde (GA) as an arm molecule onto an amino-functional surface. The p16 ^INK4A gene was used as the model target for the methylation detection of early cancer diagnosis. An amino-modified DNA probe was successfully assembled on the GA-coupling surface through the formation of Schiff base under potential control. The hybridization of amino-modified DNA probes with the target was investigated by means of electrochemical measurements, including cyclic voltammetry and square wave voltammetry. Furthermore, the functions of GA coupling for sequence-specific detection were compared with those obtained based on mercaptopropionic acid. Hybridization experiments indicated that the covalent coupling of GA was suitable for the immobilization of DNA probe and was sensitive to the electrochemical detection of single-base mismatches of label-free DNA targets in hybridization. Moreover, reported probe-modified surfaces exhibited excellent stability, and the hybridization reactions were found to be completely reversible and highly specific for recognition in subsequent hybridization processes. The strategy provided the potential for taking full advantage of existing modified electrode technologies and was verified in microarray technology, which could be applied as a useful and powerful tool in electrochemical biosensor and microarray technology.     

Use of enriched <Superscript>74</Superscript>Se and <Superscript>77</Superscript>Se in combination with isotope pattern deconvolution to differentiate and determine endogenous and supplemented selenium in lactating rats

A quantitative methodology has been developed to differentiate between endogenous and supplemented selenium in lactating rats using two enriched selenium isotopes. Lactating rats were fed for 2 weeks with formula milk containing one enriched Se isotope, ⁷⁷Se, as the metabolic tracer. The isotopic composition of selenium in serum and urine samples was then measured by collision cell ICP-MS after the addition of a solution containing another enriched isotope, ⁷⁴Se, as quantitation tracer, before analysis. Isotope pattern deconvolution allowed the transformation of measured Se isotopic abundances into concentrations of natural abundance (endogenous) selenium and enriched ⁷⁷Se (supplemented) present in the samples. The proposed methodology was validated using serum and urine reference materials spiked with both ⁷⁷Se and ⁷⁴Se. The obtained results are discussed in terms of selenium exchange and half-life in lactating rats (11–12 days) and selenium levels in serum in comparison with non-supplemented rats and control rats after maternal feeding.     

Removal of <Superscript>60</Superscript>Co<Superscript>2+</Superscript> and <Superscript>137</Superscript>Cs<Superscript>+</Superscript> ions from low radioactive solutions using <Emphasis Type="Italic">Azolla caroliniana</Emphasis> willd. water fern

This study concerns the removal of the ¹³⁷Cs⁺ and ⁶⁰Co²⁺ β+γ-radioactive ions in Azolla caroliniana Willd. water fern. The living fern and two different types of biosorbent prepared from Azolla caroliniana were tested to remove the above-mentioned radioactive ions from dilute solutions, in the absence and in the presence of the ionic competition. Effective ¹³⁷Cs⁺ and ⁶⁰Co²⁺ ions removal from low radioactive wastewaters was demonstrated. The time dependent K _d (t) values were calculated from the absorption data. These results indicate that removal process achieved equilibrium in about 120 min and that it involves two steps: rapid and slow absorption; the active process (metabolic bioaccumulation on the living fern) was responsible for above one half of the total removal process. A thin layer radiochromatography study leads to the conclusion that the biochemical components in which ¹³⁷Cs⁺ and ⁶⁰Co²⁺ place themselves are of a polysaccharide and lipoid fractions.     

Determination of <Superscript>228</Superscript>Ra in human bone ash containing significant quantities of <Superscript>40</Superscript>K and Ca<Superscript>2+</Superscript>

The determination of ²²⁸Ra by means of γ-spectrometry, in material containing significant quantities of ⁴⁰K and Ca²⁺ such as bone ash results in increased values of counting uncertainty and lower limit of detection (LLD) because of a significant contribution from the Compton continuum of ⁴⁰K. However, ⁴⁰K is widely removed from bone ash if ²²⁸Ra is coprecipitated with barium sulfate. As a result, the counting uncertainty and LLD are significantly reduced. A method is presented for determination of very low activity concentrations of ²²⁸Ra. Impurities introduced by precipitation are negligible when applying high resolution γ-spectrometry.     

Comprehensive mass spectrometry based metabolic profiling of blood plasma reveals potent discriminatory classifiers of pancreatic cancer

Poor outcome of pancreatic cancer necessitates development of an early diagnostic method to reduce mortality. No reliable early diagnostic test for pancreatic cancer detection has been developed and validated to date. In the current study, metabolic profiling of plasma samples from selected cancer patients and noncancerous controls was performed to seek novel metabolic biomarkers of pancreatic cancer. A comprehensive mass spectrometry based analytical platform established at the Metabolomics Core of the UC Davis Genome Center allowed detection of multiple compounds previously unreported in plasma from pancreatic cancer patients. It was found that selective amino acids, bile acids, and polar lipids were detected with increased or decreased levels in pancreatic cancer samples compared to controls. These findings on blood plasma levels of the relevant metabolites might be very useful clinical parameters for early diagnosis of pancreatic cancer. Copyright © 2010 John Wiley & Sons, Ltd.     

Pattern recognition analysis for <Superscript>1</Superscript>H NMR spectra of plasma from hemodialysis patients

¹H NMR spectroscopic and pattern recognition-based methods (NMR-PR) were applied to the metabolic profiling studies on hemodialysis (HD). Plasma samples were collected from 37 patients before and after HD and measured by 600 MHz NMR spectroscopy. Each spectrum was data-processed and subjected to principal component analysis for pattern recognition. Spectral patterns of plasma between pre- and post-dialyses were clearly discriminated, together with significant fluctuations in the levels of creatinine, trimethylamine-N-oxide, glucose, lactate, and acetate, which were quantitated. We have first observed the significant elevation of lactate levels in post-dialysis plasma. The present study has demonstrated the high feasibility of NMR-PR method for monitoring the dialysis condition and comprehensive profiling of the change of low-molecular-weight metabolites in HD. Figure PCA for 1H NMR spectra of plasma from HD patients     

Determination of HEPES in <Superscript>68</Superscript>Ga-labeled peptide solutions

A practical and reliable HPLC method was used for the determination of 2-[4-N-(2-hydroxyethyl)-1-piperazinyl]-N′-ethanesulfonic acid (HEPES) content in the ⁶⁸Ga-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-octreotide (DOTANOC). Linearity of this method was observed in a concentration range of 0.01–10 mg mL⁻¹ and the quantitative limit (signal to noise = 11) was determined as 10 μg mL⁻¹. The HEPES concentration in the final products of ⁶⁸Ga-DOTANOC was typically lower than the detection limit. Pure water and HEPES buffer as reaction medium were investigated using various activities of gallium-68. It was demonstrated that the presence of HEPES buffer consistently furnished very high radiochemical purity of ⁶⁸Ga-DOTANOC, which remained stable for several hours post-labeling. Evidence is provided that in addition to its role as a buffer, HEPES also functions as a radioprotectant agent.     

Searching for serum tumor markers for colorectal cancer using a 2‐D DIGE approach

Identification of specific protein markers for colorectal cancer (CRC) could provide a basis for its early diagnosis and detection, as well as clues to the molecular mechanisms governing cancer progression. In the present study, 2‐D DIGE coupled with MS was used to screen for biomarker candidates in the serum proteome of ten human CRC samples and ten healthy control samples. After pooling identical amounts of serum proteins (based on total protein concentration), albumin/IgG was depleted under partially denaturing conditions. Subsequently, the serum samples were labeled with three different CyDyes, and separated by 2‐D DIGE. After analysis with the biological variation analysis module of the DeCyder software, only three spots were found to be significantly elevated in all patient groups (with ratios from 1.52 to 9.08), whereas five spots were significantly down‐regulated in patients (with ratios from ?1.23 to ?10.21) (t‐test; p<0.05). Finally, two potential biomarkers, Transaldolase 1 and thyroid receptor interactor, were chosen for validation and analysis by ELISA with the serum of 30 CRC patients and 30 healthy controls. The serum levels of the two proteins correlated well with the 2‐D DIGE results. Thus, 2‐D DIGE approaches show great promise for biomarker discovery in CRC.     

Estimation of <Superscript>235</Superscript>U concentration in some depleted uranium samples by high resolution gamma-ray spectrometry using 185 keV and 1001 keV gamma-energies of <Superscript>235</Superscript>U and <Superscript>234m</Superscript>Pa

The migration of ²³⁷Np in an undisturbed Chinese loess column was investigated by direct γ-ray method. The column was taken from a field test site and installed in a laboratory simulation hall. Radionuclide ²³⁷Np in the form of neptunium nitrate, mixed with quartz, was introduced into the column and covered with loess. Artificial rainfall was applied to the column for about 3 years and, the counting rates of ²³⁷Np in the column from 56 to 616 days at different vertical positions were detected with a γ-ray detection system. Based on the counting rates of ²³⁷Np in the simulation column at different vertical positions and the distance from the source layer, the relationship of the mass center of ²³⁷Np in the column at different experimental periods to the experimental time was established, C _m = 0.36 log(t)-2.75. Here C _m is the mass center of ²³⁷Np in the column, cm, and t is the experimental time in days. Based on this relationship, the mass center of ²³⁷Np for the 1,073-day experiment was predicted and compared to that obtained with the final destructive method. The good agreement between the prediction and the experimental values indicates that the direct γ-ray method could be used to predict the migration of strongly adsorbed radionuclides such as ²³⁷Np in environmental media with the help of laboratory simulation columns.     

Paper radiochromatography for evaluation of radiochemical purity and stability of [<Superscript>186g</Superscript>Re]Re-HEDP in biological samples after human administration

[^186gRe]Re-HEDP is a radiopharmaceutical used for pain palliation in bone metastases from various primary tumors. The negatron emitter with 〈E _β 〉 = 357 keV ^186gRe is suitable to irradiate cancer and inflammatory cells, but it needs labeling bis-phosphonates as vectors to reach target tissue. Paper radiochromatography was used to evaluate the radiochemical purity of [^186gRe]Re-HEDP in radiopharmaceutical solution as well as in biological samples (serum and urine) from treated patients, in order to follow bone-targeting and excretion. Following the activity concentration in each sample vs. time it is effective to elaborate a bio-kinetic model of the radiopharmaceutical and to optimize administration protocols.     

Simultaneous determination of thirteen kinds of amino acid and eight kinds of acylcarnitine in human serum by LC–MS/MS and its application to measure the serum concentration of lung cancer patients

Easy‐to‐use early cancer detection methods based on metabolomics using serum samples have been developed recently. Among metabolites, amino acids and acylcarnitine are two of the most suitable candidates for diagnosing lung cancer. The purpose of the present study was to develop a novel, sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method to simultaneously determine 13 amino acids and 8 acylcarnitines in lung cancer patients in serum. After derivatization, the 21 analytes were separated using a C₁₈ column with gradient elution program in 14 min, obtaining recovery within 90.4–113.8% and precision within 0.3–14.8%. The method was successfully applied in concentration determination of lung cancer patients and healthy controls. The results showed that the serum concentration of lung cancer patients were significant from those of healthy controls.     

Sequential separation of <Superscript>99</Superscript>Tc, <Superscript>94</Superscript>Nb, <Superscript>55</Superscript>Fe, <Superscript>90</Superscript>Sr and <Superscript>59/63</Superscript>Ni from radioactive wastes

A sequential separation procedure has been developed for the determination of ⁹⁹Tc, ⁹⁴Nb, ⁵⁵Fe, ⁹⁰Sr and ^59/63Ni in various radioactive wastes generated from nuclear power plants. Ion exchange and extraction chromatography were adopted for individual separation of the radionuclides. Precipitation was supplementarily utilized for both purification of the individual radionuclides and preparation of the radionuclide sources for use in a radioactivity measurement. The chromatographic separation behavior of the radionuclides both from the sample matrix metals and from one another was investigated using stable metals, Re (as a surrogate of ⁹⁹Tc), Nb, Fe, Sr and Ni. The validity of the procedure for reliability and applicability was evaluated by measuring the recovery of the metal carriers added to synthetic radioactive waste solutions. The recoveries by the chromatographic separation were in the range of 84.8 to 102.2% with 2s of less than 8.6%, the recoveries by the precipitation being in the range of 84.3 to 97.3% with 2s of less than 10.9%.     

Determination of <Superscript>241</Superscript>Am/<Superscript>243</Superscript>Am ratios

Determination of ²⁴¹Am/²⁴³Am ratios is required for vanous purposes including assay of Am by isotope dilution techniques. Alpha-spectrometry on electrodeposited sources is a preferred technique for this determination. However, there is an inherent problem of tail contribution which necessitates the use of suitable algorithms to account for the same. Recently, in the frame of a Coordinated Research Program (CRP) of the International Atomic Energy Agency (IAEA), WinALPHA software has been developed which is a combination of an asymmetrical Gaussian for the main part of the peak and a low energy function. Therefore, it was of interest to compare the use of this algorithm with the routinely used method, in our laboratory, based on geometric progression (G. P.) decrease. Since, there are no reference materials available commercially for ²⁴¹Am/²⁴³Am ratios, synthetic mixtures covening a wide range (0.3 to 2.0) of ²⁴¹Am/²⁴³Am α-activity ratios were used and un-ignited electrodeposited sources were prepared for α-spectrometry. The α-spectra obtained using PIPS detector, were evaluated using the two algonthms The ²⁴¹Am/²⁴³Am α-activity ratios obtained were also compared with those determined by thermal ionization mass spectrometry (TIMS). An agreement of about 1% was obtained in the ²⁴¹Am/²⁴³Am ratios determined by the two methods and also by using the two algorithms for α-spectrum evaluation.     

Low level detection of <Superscript>135</Superscript>Cs and <Superscript>137</Superscript>Cs in environmental samples by ICP-MS

The measurement of fission product cesium isotopes ¹³⁵Cs and ¹³⁷Cs at low femtogram (fg) 10⁻¹⁵ levels in ground water by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is reported. To eliminate the natural barium isobaric interference on the cesium isotopes, in-line chromatographic separation of the cesium from barium was performed followed by high sensitivity ICP-MS analysis. A high efficiency desolvating nebulizer system was employed to maximize ICP-MS sensitivity ~10 cps/fg. The three sigma detection limit for ¹³⁵Cs was 2 fg/mL (0.1 μBq/mL) and for ¹³⁷Cs 0.9 fg/mL (0.0027 Bq/mL) measured from the standard with analysis time of less than 30 min/sample. Cesium detection and 135/137 isotope ratio measurement at very low femtogram levels using this method in a spiked ground water matrix is also demonstrated.     

Serum fatty acid profiles and potential biomarkers of ankylosing spondylitis determined by gas chromatography–mass spectrometry and multivariate statistical analysis

Ankylosing spondylitis (AS) is a common chronic inflammatory rheumatic disease. Early and accurate detection is essential for effective disease treatment. Recently, research has focused on genomics and proteomics. However, the associated metabolic variations, especially fatty acid profiles, have been poorly discussed. In this study, the gas chromatography–mass spectrometry (GC‐MS) approach and multivariate statistical analysis were used to investigate the metabolic profiles of serum free fatty acids (FFAs) and esterified fatty acids (EFAs) in AS patients. The results showed that significant differences in most of the FFA (C12:0, C16:0, C16:1, C18:3, C20:4, C20:5, C22:5 and C22:6) and EFA (C12:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:4 and C22:6) concentrations were found between the AS patients and healthy controls (p < 0.05). Principal component analysis and partial least squares discriminant analysis were performed to classify the AS patients and controls. Additionally, FFAs C20:4, C12:0, C18:3 and EFAs C22:6, C12:0 were confirmed as potential biomarkers to identify AS patients and healthy controls. The present study highlights that differences in the serum FFA and EFA profiles of AS patients reflect the metabolic disorder. Moreover, FFA and EFA biomarkers appear to have clinical applications for the screening and diagnosis of AS. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination and differentiation of <Superscript>226</Superscript>Ra and <Superscript>222</Superscript>Rn by gamma-ray spectrometry in drinking water

The analysis of ²²⁶Ra in natural waters can be tedious and time-consuming. For the determination and differentiation of activities of ²²⁶Ra and ²²²Rn in drinking water by γ-ray spectrometry a simple and fast method is presented. Activities of ²²⁶Ra > 0.5 Bq L⁻¹ can be determined according to stabilization of the sample without further procedures. For a more sensitive detection sample volumes of up to 5 litres are applicable by a rapid precipitation procedure without large expenditure. Further laborious enrichment methods are not necessary. Thus, detection limits of 0.1 Bq L⁻¹ can be obtained when using sample volumes of 5 litres. Therefore the method is suitable for the monitoring of radioactivity in drinking water samples in accordance with the legal guidance of the European Union.     

Separation and purification of <Superscript>249</Superscript>Cf and <Superscript>245</Superscript>Cm

There is a need to provide radioactivity standards of the higher actinides in support of both decommissioning and remediation activities as well as routine environmental analysis. In the case ²⁴⁹Cf, this will provide a useful calibration nuclide for both α-and γ-spectrometry as well as improving knowledge of the decay scheme for this nuclide. There is anecdotal evidence to suggest that the chemical yield of americium and curium may differ in radiochemical analysis. Thus, a chemical yield tracer of ²⁴⁵Cm may help to resolve this issue and will be suitable for both, suitable for use as a chemical yield tracer for both α-particle spectrometry and mass spectrometry. An aged source of ²⁴⁹Cf was used as the source material for the separation of these two nuclides by cation-exchange, using 2-hydroxy-2-methyl-propanoic acid at controlled pH as an eluant, ²⁴⁹Cf being eluted before the ²⁴⁵Cm daughter. The purity of both nuclides was measured by γ-ray spectrometry.     

Biosorption of <Superscript>241</Superscript>Am by <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>: Preliminary investigation on mechanism

As an important radioisotope in nuclear industry and other fields, ²⁴¹Am is one of the most serious contamination concerns due to its high radiation toxicity and long half-life. The encouraging biosorption of ²⁴¹Am from aqueous solutions by free or immobilized Saccharomyces cerevisiae (S. cerevisiae) has been observed in our previous experiments. In this study, the preliminary evaluation on mechanism was further explored via chemical or biological modification of S. cerevisiae, and using europium as a substitute for americium. The results indicated that the culture times of more than 16 hours for S. cerevisiae was suitable and the efficient adsorption of ²⁴¹Am by the S. cerevisiae was able to achieve. The pH value in solutions decreased gradually with the uptake of ²⁴¹Am in the S. cerevisiae, implying that H⁺ released from S. cerevisiae via ion-exchange. The biosorption of ²⁴¹Am by the decomposed cell wall, protoplasm or cell membrane of S. cerevisiae was same efficient as by the intact fungus. However, the adsorption ratio for ²⁴¹Am by the deproteinized or deacylated S. cerevisiae dropped obviously, implying that protein or carboxyl functional groups of S. cerevisiaece play an important role in the biosorption of ²⁴¹Am. Most of the investigated acidic ions have no significant influence on the ²⁴¹Am adsorption, while the saturated EDTA can strong inhibit the biosorption of ²⁴¹Am on S. cerevisiae. When the concentrations of coexistent Eu³⁺, Nd³⁺ were 100 times more than that of ²⁴¹Am, the adsorption ratios would decrease to 65% from more than 95%. It could be noted by transmission electron microscope (TEM) analysis that the adsorbed Eu is almost scattered in the whole fungus, while Rutherford backscattering spectrometry (RBS) analysis indicated that Ca in S. cerevisiae have been replaced by Eu via ion-exchange. All the results implied that the adsorption mechanism of ²⁴¹Am on S. cerevisiae is very complicated and at least involved in ion exchange, complexation process as well as well as nonspecific adsorption in cell wall because of static electricity.     

Preparation of <Superscript>26</Superscript>Al, <Superscript>59</Superscript>Ni, <Superscript>44</Superscript>Ti, <Superscript>53</Superscript>Mn and <Superscript>60</Superscript>Fe from a proton irradiated copper beam dump

The station for pions cancer therapy was operated at PSI from 1980 to 1992. After a cooling time of 12 years it’s made of copper beam dump was cut and samples were taken for analytical purposes. The sampling collected about 500 g of high active copper chips that can be used for separation of exotic radionuclides. The analyses by gamma spectrometry, LSC and AMS showed main nuclides present to be ⁶⁰Co, ⁵⁴Mn, ²²Na, ⁶⁵Zn, ²⁶Al, ⁵³Mn, ⁵⁹Ni, ⁶³Ni, ⁵⁵Fe and ⁶⁰Fe and ⁴⁴Ti with a daughter nuclide ⁴⁴Sc. In the frame of ERAWAST project a procedure combining selective precipitation and ion exchange for the separation of the rare radionuclides from the copper beam dump was developed. The proposed separation procedure is easy for remote controlled implementation in a hot cell. The ion exchange separation of Ni, Al, Mg, Ti and Fe was complete and high decontamination factors for copper and cobalt were achieved. Based on the developed procedure a remotely controlled system for separation of exotic radionuclides from the copper chips was set up. The full scale system was installed in a hot cell where high activity levels can be handled. In order to evaluate the reliability and functionality of the system extensive tests have been done. During the test period 13.86 g in total of the proton irradiated copper beam dump were processed for separation of ²⁶Al, ⁵⁹Ni, ⁵³Mn, ⁴⁴Ti and ⁶⁰Fe. The results showed that the system was operational and the radionuclide separation was selective with high chemical yield. The procedure manages as well the generated liquid wastes containing high level of ⁶⁰Co activity.     

<Superscript>234</Superscript>U/<Superscript>235</Superscript>U activity ratios as a probe for the <Superscript>238</Superscript>U/<Superscript>235</Superscript>U half-life ratio

High-resolution alpha-particle spectrometry was performed on three uranium materials enriched in ²³⁵U. Besides the ²³⁵U peaks, separate peaks belonging to impurity traces of ²³⁴U could be quantified. Relying on the isotopic composition of the uranium, as determined by mass spectrometry, the ratio of the half-lives of ²³⁸U and ²³⁵U was determined via the activity ratio of ²³⁴U and ²³⁵U in the materials. As an intermediate link, the ²³⁴U/²³⁸U half-life ratio was taken from published mass spectrometric analyses of ‘secular equilibrium’ uranium material. The resulting half-life ratio T _1/2(²³⁸U)/T _1/2(²³⁵U) = 6.351±0.031 is in agreement with the commonly adopted half-life values determined by Jaffey et al.