Low Pg Research Articles

Preliminary study on brominated dioxins/furans and hydroxylated/methoxylated PBDEs in Baltic cod (Gadus morhua) liver. Comparison to the levels of analogue chlorinated co-occurring pollutants

Low pg levels of PBDD/Fs in 0.8–38.9pgg−1 (fat) range (mean 14.2pgg−1) observed in the tested cod liver samples were significantly lower than levels of their chlorinated analogues (25.1–95.9 range, 37.7 mean pgg−1 fat). Brominated furans dominated the congener profile. Elevated levels of OH-/MeO-BDE were however observed with mean concentrations at 2769±1319 and 5441±2918pgg−1 (fat) respectively. The observed congener profiles with the predominance of 6-OH-BDE 47 and the relatively high proportion between the native and hydroxylated compounds indicate on natural origin of those compounds or at least presence of various exposure sources. A large fraction of studied samples did not comply with the currently standing EU regulations concerning PCBs and chlorinated dioxins (11%), especially as regards non-dioxin like PCBs (88%).

Total mercury in snow and ice samples from Canadian High Arctic ice caps and glaciers: A practical procedure and method for total Hg quantification at low pg g− 1 level

A newly developed procedure and method for studying total Hg (THg) in the High Arctic glaciers and ice caps, including container type selection, on-site sampling, sample protection and storage, and sample decontamination is reported in this study. Two analytical systems for THg quantification were also compared to confirm the accuracy and reproducibility.This study found that container types, storage time, sample protection from exposure to light and environment are all important for precise quantification of THg in snow and ice samples from the Canadian High Arctic glaciers and ice caps.With this newly developed procedure and method, we retrieved 28-year and 73-year archives for atmospheric THg deposition from Mt. Oxford and Agassiz Ice Cap respectively. Our results show that snow and ice samples contain THg concentrations varying from sub pgg−1 to low pgg−1. Comparison of THg concentration trends and fluxes from the two sites demonstrates that quantification of THg from the two locations with similar altitudes and latitudes can be reproducible, which suggests that historical THg information from atmospheric deposition can be preserved in snow and ice in the glaciers and ice caps. The high reproducibility of results achieved by this procedure and method, in return, confirmed its suitability for studies of THg in snow and ice samples from ice caps and glaciers.

Level of serum antibody against a periodontal pathogen is associated with atherosclerosis and hypertension

Inflammation has a role in the pathogenesis of atherosclerosis, which causes hypertension. Results from some studies have suggested links between periodontal disease and atherosclerosis, but links between periodontal disease and hypertension have been seldom studied. We investigated whether periodontal disease and serum antibody level were associated with hypertension. We studied 127 patients (93 men and 34 women, mean age 68±9 years) who were admitted with ischemic heart disease to our institution. A composite periodontal risk score was calculated from five periodontal vector scores. The levels of serum antibody against Porphyromonas gingivalis (Pg) were measured. Pulse pressure, mean blood pressure (BP) and pulse wave velocity were used as indices of atherosclerosis. We divided patients into two groups according to the levels of serum antibody against Pg: higher or equal to the median (high Pg antibody group) and lower than the median (low Pg antibody group).There was no difference in the use of antihypertensive agents between the two groups. The composite periodontal risk score (P=0.0003), systolic BP (P=0.030), diastolic BP (P=0.038), pulse pressure (P=0.050) and mean BP (P=0.055) were higher in the high Pg antibody group than in the low Pg antibody group. The composite periodontal risk score (r=0.320, P=0.0003), systolic BP (r=0.212, P=0.017), diastolic BP (r=0.188, P=0.035) and mean BP (r=0.225, P=0.011) correlated with the level of serum antibody against Pg, even after adjustment for age. An elevated antibody level against Pg indicates advanced periodontal disease and suggests advancement of atherosclerosis and hypertension.

High hydrostatic pressure/temperature modeling of frankfurter batters

The impact of high pressure/temperature treatment on structure modification and functional sensory properties of frankfurter batter was investigated. The degree of solubilization of meat proteins, particularly of myosin, was identified as a key process with significant effect on the batter's structural properties. The maximal solubilization level was at 200MPa/40°C IT for all formulations which was found to be treatment time dependent. The impact of the pressurizing gradient — PG=40MPa/s and PG=2.5MPa/s was investigated and estimated to have a significant effect on the protein network and functional properties, respectively. These were improved at low PG (2.5MPa/s) as a phenomenon of secondary network formation parallel to the main matrix. Batter secondary-structure characteristics were found to be ionic-strength dependent. According to SDS-PAGE analysis, the major role in the solubilization, aggregation and gelation processes occurring in the aqueous phase was due to the myosin S-1 and S-2, N-terminal, C-terminals, the MLC and actin during the high pressure/temperature treatment.

Biochemical tolerance during low dose propylene glycol exposure in neonates: A formulation-controlled evaluation

Background and purpose of the studyPropylene glycol (PG) is a frequently co-administered solvent in formulations administered to neonates, but reports on its (in)tolerance are limited. We aimed to report on renal, metabolic and hepatic tolerance before, during and following intravenous (iv) PG-paracetamol exposure and compared these data with similar datasets reported in literature on neonates exposed to PG without paracetamol or paracetamol without PG.MethodsRenal (diuresis, creatinemia, sodium), metabolic (Base Excess, Anion Gap, lactate, bicarbonate) and hepatic (liver enzymes, bilirubinemia) indicators before, during and following iv paracetamol-PG exposure in neonates as included in the PARANEO (paracetamol in neonates) study (intra-individual trends, ANOVA) were collected and analysed. Comparison with observations collected in cases exposed to either iv phenobarbital-PG or iv paracetamol-mannitol (inter-individual comparison, Mann Whitney-U test) were made.ResultsPG exposure (median 34.1 mg/kg/24 h) did not affect postnatal renal, metabolic and hepatic adaptations in 60 cases exposed to paracetamol-PG. These indicators were similar when compared to 29 cases exposed to phenobarbital-PG or 172 cases exposed to paracetamol-mannitol.Major conclusionBased on observations in 89 neonates, low dose PG exposure was tolerated well. Studies on PG pharmacokinetics and its covariates are needed to estimate the upper level of PG tolerance in neonates.

High-speed cryo-focusing injection for gas chromatography: Reduction of injection band broadening with concentration enrichment

In order to maximize peak capacity and detection sensitivity of fast gas chromatography (GC) separations, it is necessary to minimize band broadening, and in particular due to injection since this is often a major contributor. A high-speed cryo-focusing injection (HSCFI) system was constructed to first cryogenically focus analyte compounds in a 6cm long section of metal MXT column, and second, reinject the focused analytes by rapidly resistively heating the metal column via an in-house built electronic circuit. Since the cryogenically cooled section of column is small (∼750nl) and the direct resistive heating is fast (∼6000°C/s), HSCFI is demonstrated to produce an analyte peak with a 6.3ms width at half height, w1/2. This was achieved using a 1m long column with a 180μm inner diameter (i.d.) operated at an absolute head pressure of 55psi and an oven temperature of 60°C, with a 10V pulse applied to the metal column for 50ms. HSCFI was also used to demonstrate the head space sampling and fast GC analysis of an aqueous solution containing six test analytes (acetone, methanol, ethanol, toluene, chlorobenzene, pentanol). Using Henry’s law constants for each of the analytes, injected mass limits of detection (LODs) were typically in the low pg levels (e.g., 1.2pg for acetone) for the high speed separation. Finally, to demonstrate the use of HSCFI with a complex sample, a gasoline was separated using a 20m×100μm i.d. column and the stock GC oven for temperature programming, which provided a separation time of 200s and an average peak width at the base of 440ms resulting in a total peak capacity of 460 peaks (at unit resolution).

Regulation of subcellular distribution and oncogenic potential of nucleophosmin by plakoglobin

Nucleophosmin (NPM) is a nucleolar phosphoprotein that is involved in many cellular processes and has both oncogenic and growth suppressing activities. NPM is localized primarily in nucleoli but shuttles between the nucleus and the cytoplasm, and sustained cytoplasmic distribution contributes to its tumor promoting activities. Plakoglobin (PG, γ-catenin) is a homolog of β-catenin with dual adhesive and signaling functions. These proteins interact with cadherins and mediate adhesion, while their signaling activities are regulated by association with various intracellular partners. Despite these similarities, β-catenin has a well-defined oncogenic activity, whereas PG acts as a tumor/metastasis suppressor through unknown mechanisms. Comparison of the proteomic profiles of carcinoma cell lines with low- or no PG expression with their PG-expressing transfectants has identified NPM as being upregulated upon PG expression. Here, we examined NPM subcellular distribution and in vitro tumorigenesis/metastasis in the highly invasive and very low PG expressing MDA-MB-231 (MDA-231) breast cancer cells and their transfectants expressing increased PG (MDA-231-PG) or NPM shRNA (MDA-231-NPM-KD) or both (MDA-231-NPM-KD+PG). Increased PG expression increased the levels of nucleolar NPM and coimmunoprecipitation studies showed that NPM interacts with PG. PG expression or NPM knockdown decreased the growth rate of MDA-231 cells substantially and this reduction was decreased further in MDA-231-NPM-KD+PG cells. In in vitro tumorigenesis/metastasis assays, MDA-231-PG cells showed substantially lower and MDA-231-NPM-KD cells substantially higher invasiveness relative to the MDA-231 parental cells, and the co-expression of PG and NPM shRNA led to even further reduction of the invasiveness of MDA-231-PG cells. Furthermore, examination of the levels and localization of PG and NPM in primary biopsies of metastatic infiltrating ductal carcinomas revealed coordinated expression of PG and NPM. Together, the data suggest that PG may regulate NPM subcellular distribution, which may potentially change the function of the NPM protein from oncogenic to tumor suppression.

Optimization of solid-phase extraction and liquid chromatography–tandem mass spectrometry for the determination of domoic acid in seawater, phytoplankton, and mammalian fluids and tissues

We previously reported a solid-phase extraction (SPE) method for determination of the neurotoxin domoic acid (DA) in both seawater and phytoplankton by liquid chromatography–tandem mass spectrometry (LC–MS/MS) with the purpose of sample desalting without DA pre-concentration. In the present study, we optimized the SPE procedure with seawater and phytoplankton samples directly acidified with aqueous formic acid without addition of organic solvents, which allowed sample desalting and also 20-fold pre-concentration of DA in seawater and phytoplankton samples. In order to reduce MS contamination, a diverter valve was installed between LC and MS to send the LC eluant to waste, except for the 6-min elution window bracketing the DA retention time, which was sent to the MS. Reduction of the MS turbo gas temperature also helped to maintain the long-term stability of MS signal. Recoveries exceeded 90% for the DA-negative seawater and the DA-positive cultured phytoplankton samples spiked with DA. The SPE method for DA extraction and sample clean-up in seawater was extended to mammalian fluids and tissues with modification in order to accommodate the fluid samples with limited available volumes and the tissue extracts in aqueous methanol. Recoveries of DA from DA-exposed laboratory mammalian samples (amniotic fluid, cerebrospinal fluid, plasma, placenta, and brain) were above 85%. Recoveries of DA from samples (urine, feces, intestinal contents, and gastric contents) collected from field stranded marine mammals showed large variations and were affected by the sample status. The optimized SPE–LC–MS method allows determination of DA at trace levels (low pg mL −1) in seawater with/without the presence of phytoplankton. The application of SPE clean-up to mammalian fluids and tissue extracts greatly reduced the LC column degradation and MS contamination, which allowed routine screening of marine mammalian samples for confirmation of DA exposure and determination of fluid and tissue DA concentrations in experimental laboratory animals.

Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

Abstract. A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter is presented. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. Particulate matter was collected on quartz fibre filters using dichotomous high volume air samplers. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography and solid phase extraction. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyl)trifluoroacetamide, was added for Gas Chromatography-Mass Spectrometry analysis. The second half of the sample was stored in a refrigerator. For samples with concentrations exceeding 1 ng μl−1, the second half of the sample was used for measurement of stable carbon isotope ratios by Gas Chromatography-Isotope Ratio Mass Spectrometry. The procedure described in this paper provides a method for the analysis of methylnitrophenols in atmospheric particulate matter at concentrations as low as 0.3 pg m−3 and for stable isotope ratios with an accuracy of better than ±0.5‰ for concentrations exceeding 100 pg m−3. In all atmospheric particulate matter samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol, with concentrations ranging from the low pg m−3 range in rural areas to more than 200 pg m−3 in some samples from a suburban location.

Low serum pepsinogen I and pepsinogen I/II ratio and Helicobacter pylori infection are associated with increased risk of gastric cancer: 14‐year follow up result in a rural Chinese community

The correlation between low serum PG level and H. pylori infection with the development of gastric cancer has caused considerable concerns all over the world. Some authors exclaimed that gastric cancer developed only in patients infected with H. pylori, whereas the other had different findings. In this study, 1,501 adult local residents with determined serum PG levels and anti H. pylori IgG status were followed for 14 years for the development of gastric cancer in a rural community with high risk of gastric cancer in Hebei Province, China. The results showed the accumulated gastric cancer incidence in the subjects with abnormal PG level and those with H. pylori infection were all significantly higher than that in the corresponding normal controls (53.9‰ vs. 12.7‰, p < 0.05 and 23.1‰ vs. 5.93‰, p < 0.05). The highest gastric cancer incidence was seen in the subjects with both abnormal serum PG and positive H. pylori (56.0‰), and followed by the subjects with abnormal PG and negative H. pylori (47.6‰) and those with normal serum PG and positive H. pylori (18.4‰). The abnormal serum PG level (OR 3.029) and H. pylori infection (OR 4.345) were all risk factors for the development of gastric cancer. The results suggested that the subjects with abnormal serum PG level and/or positive H. pylori infection in the rural area of China were all high risk population for gastric carcinoma and the subjects with both abnormal serum PG and positive H. pylori infection were at especially high risk for the development of gastric carcinoma.

Brominated Flame Retardants in Seawater and Atmosphere of the Atlantic and the Southern Ocean

Seawater and air samples were collected aboard the FS Polarstern during the cruises ANT-XXV/1 + 2 in the Atlantic and Southern Ocean in 2008. The particulate and dissolved phase in water and particulate and gaseous phase in air were analyzed separately for nine polybrominated diphenyl ethers (PBDEs) and six non-PBDE brominated flame retardants (BFRs). Air concentrations of 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) and hexabromobenzene (HBB) in the gaseous and particulate phase (median = 0.56 pg m(-3) for DPTE and 0.92 pg m(-3) for HBB) were comparable to ∑(9)PBDEs (1.0 pg m(-3)). Pentabromotoluene (PBT) was detectable in ∼30% of the gaseous phase samples, whereas concentration of 2,4,6-tribromophenyl allylether (ATE), hexachlorocyclopentenyl-dibromocyclooctane (HCDBCO) and 2-ethyl-1-hexyl 2,3,4,5-tetrabromobenzoate (EHTBB) were below their method detection limits. DPTE, and PBDEs were also found in seawater at low pg per liter levels. Elevated seawater concentrations of PBDEs and DPTE were measured in the English Channel and close to South African coast. Concentrations of DPTE, BDE-47, and BDE-99 in the atmosphere generally decreased from Europe toward the Southern Ocean, whereas no latitudinal trend was observed in seawater. Air-water exchange gradients suggested net deposition dominates for all selected substances. The medians of net deposition fluxes for the air-water gas exchange were 83, 21, 69, 20, and 781 pg m(-2) day(-1) for BDE-47, BDE-100, BDE-99, DPTE, and HBB, whereas medians of dry deposition fluxes were 2.0, 0.3, 1.2, 1.0, and 0.5 pg m(-2) day(-1) for BDE-47, BDE-100, BDE-99, DPTE, and HBB. Overall, these results highlight the important role of the long-range atmospheric transport of PBDE and non-PBDE BFRs to remote regions.

Quantitative determination of mycotoxins in urine by LC-MS/MS

Naturally occurring mycotoxins are responsible for a wide array of adverse health effects. The measurement of urinary mycotoxin levels is a useful means of assessing an individual's exposure, but the development of sensitive and accurate analytical methods for detecting mycotoxins and their metabolites in urine samples is challenging. Urinary mycotoxins are present in low pg ml–1 concentrations, and the chromatographic identification of their metabolites can be obscured by other endogenous metabolites. We developed an analytical method focused on the selection of two appropriate multiple-reaction monitoring transition for unambiguous identification and quantification of carcinogenic aflatoxin M1 (AFM1), ochratoxin A (OTA) and fumonisin B1, B2 (FB1, FB2) in urine samples from a small volunteer group in a pilot study. AFM1, OTA, FB1 and FB2 were concentrated selectively, interfering substances were removed using an immunoaffinity column (IAC), and mycotoxins were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in combination with a stable-isotope standard-dilution assay (SIDA). The method was sensitive enough to measure mycotoxins and their metabolites at pg ml–1 levels in urine. The combination of LC-MS/MS and SIDA was critical to distinguishing pseudo-OTα interference from genuine OTα. Twelve urine samples contained OTA ranging from 0.013 to 0.093 ng ml−1 (mean = 0.031 ng ml−1). AFM1 were detected in one sample at a 0.002 ng ml−1 level, while FB1 and FB2 were undetectable in all 12 samples. None of the samples in this pilot study contained a detectable level of OTα, despite the presence of OTA, and this may suggest the need for further epidemiological investigation of OTA exposure in the Korean population.

Development of a fast liquid chromatography–tandem mass spectrometry method for the determination of endocrine-disrupting compounds in waters

A fast liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method was developed to study five endocrine-disrupting compounds (4-n-nonylphenol, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol) in water. Different columns were tested; the chromatographic separation of the analytes was optimized on a Pinnacle DB biphenylic column with a water-acetonitrile gradient elution, which allowed the separation of the selected endocrine-disrupting compounds (EDCs) in less than 6 min. Quantitative analysis was performed in selected reaction monitoring (SRM) mode; two transitions were chosen for each compound, using the most abundant for quantitation. Calibration curves using bisphenol A-d (16) as internal standard were drawn, showing good correlation coefficients (0.9993-0.9998). All figures of merit of the method were satisfactory; limits of detection were in the low pg range for all analytes. The method was then applied to the determination of the analytes in real water samples: to this aim, polar organic chemical integrative samplers (POCIS) were deployed in the influent and in the effluent of a drinking water treatment plant in Liguria (Italy). The EDC level was rather low in the influent and negligible in the outlet, reflecting the expected function of the treatment plant.

Polyfluoroalkyl compounds in the East Greenland Arctic Ocean

Polyfluoroalkyl compounds (PFCs) can be found ubiquitously in the marine environment. The transport of PFCs to remote locations is assumed to be by direct transport via oceanic water currents or indirectly via atmospheric transport of volatile precursor compounds. This study investigates the influence of ocean currents and atmospheric transport to the East Greenland Arctic Ocean (67.5-80.4 degrees N). In this study, 38 water samples were collected in the Arctic summer in 2009 and analyzed by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Concentrations of three PFC classes could be quantified (i.e., perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkyl sulfonates (PFSAs) and perfluoroalkyl sulfonamides) predominantly in a low pg L(-1) range. Dominating compounds were PFOSA and PFOA with mean concentrations of 61 pg L(-1) and 51 pg L(-1), respectively. Statistically significant higher concentrations for PFOSA and PFHxA in the samples taken north of 75 degrees N indicate an atmospheric influence on the concentrations found in the water samples. Significant differences in concentrations of PFHxS, PFHxA, PFHpA and PFOA for samples taken in coastal areas indicate an influence from the Greenlandic mainland.

Direct multi-element analysis of crude oils and gas condensates by double-focusing sector field inductively coupled plasma mass spectrometry (ICP MS)

A double-focusing sector field ICP MS was optimized for the direct simultaneous determination of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sn, Ti, V in organic solutions. Polyatomic interferences originating from the carbon-rich matrix were completely eliminated at a resolution of 4000 allowing the detection limits at the low pg g−1 level to be obtained (typically one order of magnitude lower than using a quadrupole ICP MS). A method for the routine comprehensive trace element analysis of xylene solutions of oil samples using external calibration was developed. It was validated by the analysis of three certified reference materials and applied to the analysis of 2 gas condensate samples and 4 oil samples of different origins.

Effects of Temperature on Interface Shear Strength of Emulsified Tack Coats and Its Relationship to Rheological Properties

The objective of this study was to investigate tack coat interface shear bond characteristics at various temperatures and to relate tack coat characteristics in the field to the rheological test results in the laboratory. Interface shear strength (ISS) of two emulsified asphalt tack coats (CRS-1 and trackless) was evaluated at temperatures ranging from −10°C to 60°C. Two emulsified tack coats were applied on full-scale pavement test sections at application rates of 0.14, 0.28, and 0.70 L/m2. Cores were then extracted from the full-scale test sites to be tested in the laboratory while simulating different field conditions. Tests were conducted with a newly developed direct shear device. The binder grade for the residue of CRS-1 emulsion was PG 58-28. The high temperature grade for the residue of the trackless emulsion was PG 82. Trackless material was brittle at a low temperature, and its low temperature PG grade could not be determined. Within the evaluated temperature range, the ISS of the tacked interface increased with the decrease in temperature. Generally, bonding performance, as measured by the ISS, of the trackless emulsion was superior to CRS-1 emulsion, specifically at temperatures greater than 40°C. In addition, results show that interface shear strength for both tack coat materials at each application rate increased with an increase of the binder rheology parameter G*/sin δ. This relationship can be used to establish a laboratory design threshold for this parameter, to ensure that the selected application rate and tack coat material will perform adequately in the field.

Determination of rare-earth elements in uranium-bearing materials by inductively coupled plasma mass spectrometry

A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-earth elements) in uranium-bearing materials by inductively coupled plasma sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg g(-1) range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology.

Quantitative analysis of trace element concentrations in some gem-quality diamonds

The geochemical signature of diamond-forming fluids can be used to unraveldiamond-forming processes and is of potential use in the detection of so-called ‘conflict’diamonds. While fluid-rich fibrous diamonds can be analyzed by a variety of techniques,very few data have been published for fluid-poor, gem-quality diamonds because of theirvery low impurity levels. Here we present a new ICPMS-based (ICPMS: inductivelycoupled plasma mass spectrometry) method for the analysis of trace element concentrationswithin fluid-poor, gem-quality diamonds. The method employs a closed-system laserablation cell. Diamonds are ablated and the products trapped for later pre-concentrationinto solutions that are analyzed by sector-field ICPMS. We show that our limits ofquantification for a wide range of elements are at the sub-pg to low pg level. The method isapplied to a suite of 10 diamonds from the Cullinan Mine (previously known as Premier),South Africa, along with other diamonds from Siberia (Mir and Udachnaya) andVenezuela. The concentrations of a wide range of elements for all the samples(expressed by weight in the solid) are very low, with rare earth elements alongwith Y, Nb, Cs ranging from 0.01 to 2 ppb. Large ion lithophile elements (LILE)such as Rb and Ba vary from 1 to 30 ppb. Ti ranges from ppb levels up to 2 ppm.From the combined, currently small data set we observe two kinds of diamond-formingfluids within gem diamonds. One group has enrichments in LILE over Nb, whereas a secondgroup has normalized LILE abundances more similar to those of Nb. These two groupsbear some similarity to different groups of fluid-rich diamonds, providing some supportingevidence of a link between the parental fluids for both fluid-inclusion-rich and gemdiamonds.

Electrochemical immunosensors for interleukin-6. Comparison of carbon nanotube forest and gold nanoparticle platforms

Electrochemical immunosensors based on single wall nanotube (SWNT) forests and 5 nm glutathione-protected gold nanoparticles (GSH-AuNP) were developed and compared for the measurement of human cancer biomarker interleukin-6 (IL-6) in serum. Detection was based on sandwich immunoassays using multiple (14–16) horseradish peroxidase labels conjugated to a secondary antibody. Performance was optimized by effective blocking of non-specific binding (NSB) of the labels using bovine serum albumin. The GSH-AuNP immunosensor gave a detection limit (DL) of 10 pg mL −1 IL-6 (500 amol mL −1) in 10 μL calf serum, which was 3-fold better than 30 pg mL −1 found for the SWNT forest immunosensor for the same assay protocol. The GSH-AuNPs platform also gave a much larger linear dynamic range (20–4000 pg mL −1) than the SWNT system (40–150 pg mL −1), but the SWNTs had 2-fold better sensitivity in the low pg mL −1 range.

The Role of Serum Pepsinogen and Gastrin Test for the Detection of Gastric Cancer in Korea

Serum pepsinogen (sPG) is a marker of gastric mucosal atrophy, a condition that has been associated with an increased risk of gastric neoplasia. A low sPGI level and a low PG I/II ratio have been associated with severe gastric atrophy, and are frequently found in gastric cancer. Because the prevalence of gastric cancer is high in Korea, it would be convenient if a good biomarker for gastric cancer were developed. Two studies recently investigated the efficacy of sPG along with Helicobacter pylori (H. pylori) as a screening tool for gastric cancer. In these studies, sPG was measured using a Latex enhanced Turbidimetric Immunoassay. We found that H. pylori IgG status, age and gender were associated with serum pepsinogen levels. Thus, to increase the ability of the PG I/II ratio to detect atrophic gastritis, the cutoff value for the PG I/II ratio should be stratified according to the H. pylori IgG status. In addition, a PG I/II ratio (), which has been widely used as an international standard for gastric cancer, was found to be a reliable marker for the detection of gastric dysplasia or gastric cancer, especially of the intestinal type. The efficacy of the test in Korea was lower than the efficacy in Japan. However, the detecting power of a PG I/II ratio () was significantly increased in the presence of H. pylori. The ratio together with H. pylori psotivitiy could provide a means of identifying persons at high risk of developing gastric cancer in Korea.