Bioanalytical and chemical assessment of the disinfection by-product formation potential: Role of organic matter

Disinfection by-products (DBP) formed from natural organic matter and disinfectants like chlorine and chloramine may cause adverse health effects. Here, we evaluate how the quantity and quality of natural organic matter and other precursors influence the formation of DBPs during chlorination and chloramination using a comprehensive approach including chemical analysis of regulated and emerging DBPs, total organic halogen quantification, organic matter characterisation and bioanalytical tools. In vitro bioassays allow us to assess the hazard potential of DBPs early in the chain of cellular events, when the DBPs react with their molecular target(s) and activate stress response and defence mechanisms. Given the reactive properties of known DBPs, a suite of bioassays targeting reactive modes of toxic action including genotoxicity and sensitive early warning endpoints such as protein damage and oxidative stress were evaluated in addition to cytotoxicity. Coagulated surface water was collected from three different drinking water treatment plants, along with reverse osmosis permeate from a desalination plant, and DBP formation potential was assessed after chlorination and chloramination. While effects were low or below the limit of detection before disinfection, the observed effects and DBP levels increased after disinfection and were generally higher after chlorination than after chloramination, indicating that chlorination forms higher concentrations of DBPs or more potent DBPs in the studied waters. Bacterial cytotoxicity, assessed using the bioluminescence inhibition assay, and induction of the oxidative stress response were the most sensitive endpoints, followed by genotoxicity. Source waters with higher dissolved organic carbon levels induced increased DBP formation and caused greater effects in the endpoints related to DNA damage repair, glutathione conjugation/protein damage and the Nrf2 oxidative stress response pathway after disinfection. Fractionation studies indicated that all molecular weight fractions of organic carbon contributed to the DBP formation potential, with the humic rich fractions forming the greatest amount of DBPs, while the low molecular weight fractions formed more brominated DBPs due to the high bromide to organic carbon ratio. The presence of higher bromide concentrations also led to a higher fraction of brominated DBPs as well as proportionally higher effects. This study demonstrates how a suite of analytical and bioanalytical tools can be used to effectively characterise the precursors and formation potential of DBPs.     

A comparison of the quantitative methods for the analysis of the platinum-containing anticancer drug [cis-[amminedichloro(2-methylpyridine)]platinum(II)] (ZD0473) by HPLC coupled to either a triple quadrupole mass spectrometer or an inductively coupled plasma mass spectrometer

The use of high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICPMS) as means for the quantitative determination of ZD0473, a platinum anticancer drug, and its related biologically active "aqua" compounds in biofluid samples is described. The performance of the resulting HPLC-ICPMS method was compared with that of a conventional HPLC-triple quadrupole mass spectrometer-based (HPLC-MS/MS) system for properties such as limit of detection, linearity, and reproducibility using spiked samples. The methods were then applied to the determination of plasma ultrafitrate concentrations of ZD0473 in dog plasma samples obtained following intravenous and oral administration at 0.5 and 6 mg/kg, respectively. These experiments showed that both methods were capable of providing accurate and precise results but that the HPLC-ICPMS method had advantages of extended linear range and superior sensitivity, providing a limit of quantification of 0.1 ng/mL for ZD0473, as compared to 5 ng/mL using the current HPLC-MS/MS method. In addition, by using a single combined HPLC-ICPMS/MS/MS system, it was possible to determine the relative MS/MS response of the aqua compounds for the first time.     

THE ORIGIN OF DOLOMITE IN THE ASMARI FORMATION (OLIGOCENE-LOWER MIOCENE), DEZFUL EMBAYMENT, SW IRAN

Dolomitisation is an important factor controlling reservoir quality in the Asmari Formation in many producing fields in SW Iran. Dolostones have higher average porosities than limestones. Petrographic and geochemical studies have been used to determine the causes of Asmari dolomitisation at the Bibi Hakimeh and Marun fields and at the Khaviz anticline. The formation is generally characterized by a large‐scale trend of upward‐decreasing accommodation. Basal strata were deposited under relatively open‐marine, high‐energy conditions, whereas the Middle to Upper Asmari succession was deposited in relatively protected settings with more frequent evidence of exposure and evaporitic conditions. There is a general upward increase in the abundance of both anhydrite (occurring as nodules and cement) and dolomite. Two main types of dolomite fabric are recognised, reflecting the textures of the precursor limestones: (1) finely crystalline pervasive dolomite (commonly <20μ) replacing mud‐rich facies; and (2) combinations of finely crystalline replacive dolomite and surrounding areas of coarser dolomite cement (crystals up to 100μ) in grain‐supported facies. Fluid inclusion data indicate that finely crystalline dolomites formed at low temperatures (ca. <50°C), while the coarser dolomite formed at higher temperatures (50–;140°C). Whole rock‐carbonate oxygen and carbon isotope analyses of pure dolostone samples show no apparent correlation with either depositional or diagenetic textures: δ¹⁸O is generally 0 to 2.7‰ PDB, and δ¹³C is ?1 to 4‰ PDB. The importance of evaporated seawater to Asmari dolomitisation is indicated by the ubiquitous occurrence of felty‐textured anhydrite nodules in dolostone beds and the presence of high‐salinity fluid inclusions in dolomite. The derivation of dolomitising fluids from contemporaneous seawater is supported by the general correspondence between age estimates derived from the strontium isotope composition of anhydrites and dolomites and those derived from stratigraphic considerations. This suggested synsedimentary dolomitisation. Dolomitisation of the upper half of the Asmari Formation may have occurred as a result of two syn‐sedimentary mechanisms: (1) by the reflux of evaporative brines concentrated in shallow lagoons or sabkhas, through immediately underlying strata (mainly during highstands); and (2) by the flushing of platform‐top carbonates by basinal evaporated waters during lowstand/early transgression. Continued dolomitisation during deeper burial is supported by the presence of high‐temperature fluid inclusions and iron‐rich crystal rims. Dolomite within the lower part of the Asmari Formation probably mostly formed during burial as a result of compaction of, and fluid exclusion from, the underlying Pabdeh marls and shales.     

Natural versus wastewater derived dissolved organic carbon: implications for the environmental fate of organic micropollutants

The interaction of organic micropollutants with dissolved organic carbon (DOC) can influence their transport, degradation and bioavailability. While this has been well established for natural organic carbon, very little is known regarding the influence of DOC on the fate of micropollutants during wastewater treatment and water recycling. Dissolved organic carbon-water partition coefficients (K_DOC) for wastewater derived and reference DOC were measured for a range of micropollutants using a depletion method with polydimethylsiloxane disks. For micropollutants with an octanol-water partition coefficient (log K_OW) greater than 4 there was a significant difference in K_DOC between reference and wastewater derived DOC, with partitioning to wastewater derived DOC over 1000 times lower for the most hydrophobic micropollutants. The interaction of nonylphenol with wastewater derived DOC from different stages of a wastewater and advanced water treatment train was studied, but little difference in K_DOC was observed. Organic carbon characterisation revealed that reference and wastewater derived DOC had very different properties due to their different origins. Consequently, the reduced sorption capacity of wastewater derived DOC may be related to their microbial origin which led to reduced aromaticity and lower molecular weight. This study suggests that for hydrophobic micropollutants (log K_OW > 4) a higher concentration of freely dissolved and thus bioavailable micropollutants is expected in the presence of wastewater derived DOC than predicted using K_DOC values quantified using reference DOC. The implication is that naturally derived DOC may not be an appropriate surrogate for wastewater derived DOC as a matrix for assessing the fate of micropollutants in engineered systems.     

The HLA A1-B8 haplotype extends 6 Mb beyond HLA-A: associations between HLA-A, B, F and 15 microsatellite markers

Ornithodoros (Alectorobius) amblus Chamberlin 1920 specimens were collected from a seagull (Larus spp.) nest in northern Chile. This reports the occurrence of this species outside Peru. The biology of 79 specimens reared under laboratory conditions at 27 degrees C, 75-80% RH, and total darkness was determined. A 13% mortality rate from larval to adult was observed. Larval ticks were fed on chicks, Gallus gallus domesticus; and nymphs and adults were fed on chickens. We recorded the number of eggs per female per gonotrophic cycle and the mean duration of the periods of preoviposition, oviposition, and incubation. The total duration of their life cycle ranged from 111 to 239 d, depending on the number of molts. Males were found after the 4th molt, and after the 5th molt the proportion of females was greater than that of males or remaining nymphs. The feeding period of larvae was 4-6 d, N1 nymphs do not feed. The N2-N6 nymphs, males and females, had a 10- to 60-min feeding period. From N2 on, there was emission of coxal fluid while on the host and during or immediately after feeding.     

Percentage discounts, initial price, and bargain hunting: A heuristic-systematic approach to price search behavior.

Consumer decisions concerning price search were investigated using the heuristic-systematic model of social judgment (S. Chaiken, A. Liberman, & A. H. Eagly, 1989). Consumers used the size of the percentage discount as a heuristic cue to help decide whether a better price was likely to be available elsewhere. However, as predicted, participants relied on this cue only when the initial base price of the item was low. In contrast, search was continued despite the offer of a large percentage discount when consumers were shopping for items that were relatively expensive. This finding was attributed to the higher potential costs associated with missing a better price when consumers were shopping for more expensive items. In general, the heuristic-systematic model proved to be a useful way to characterize price search decisions. It was also suggested that these findings might be useful in explaining some conflicting results in the price search literature. Implications for behavioral price theories are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A screening level fate model of organic contaminants from advanced water treatment in a potable water supply reservoir

Augmentation of potable water sources by planned indirect potable reuse of wastewater is being widely considered to address growing water shortages. Environmental buffers such as lakes and dams may act as one of a series of barriers to potable water contamination stemming from micropollutants in wastewater. In South-East Queensland, Australia, current government policy is to begin indirect potable reuse of water from reverse osmosis equipped advanced water treatment plants (AWTPs) when the combined capacity of its major storages is at 40% capacity. A total of 15 organic contaminants including NDMA and bisphenol A have been publically reported as detected in recycled water from one of South-East Queensland’s AWTPs, while another 98 chemicals were analysed for, but found to be below their detection limit. To assess the natural attenuation in Lake Wivenhoe, a Level III fugacity based evaluative fate model was constructed using the maximum concentrations of these contaminants detected as input data. A parallel aquivalence based model was constructed for those contaminants, such as dichloroacetic acid, dalapon and triclopyr, which are ionised in the environment of Lake Wivenhoe. A total of 247 organic chemicals of interest, including disinfection by-products, pesticides, pharmaceuticals and personal care products, xenoestrogens and industrial chemicals, were evaluated with the model to assess their potential for natural attenuation. Out of the 15 detected chemicals, trihalomethanes are expected to volatilise with concentrations in the outflow from the dam approximately 400 times lower than influent from the AWTPs. Transformation processes in water are likely to be more significant for NDMA and pharmaceuticals such as salicylic acid and paracetamol as well as for caffeine and the herbicides dalapon and triclopyr. For hydrophobic contaminants such as cholesterol and phenolic xenoestrogens such as 4-nonylphenol, 4-t-octylphenol and bisphenol A, equilibrium between water and sediments will not be attained and hence fate processes such as removal in outflow are predicted to become relatively important.     

Effects of anxiety on inferential reasoning task performance.

Three experiments were conducted in which high anxiety and low anxiety subjects were required to construct inferences. In Experiment 1 there was no anxiety-related performance deficit when inferring a necessary anaphoric relation, a process argued to be automatic. Experiments 2 and 3 involved the verification of unnecessary inferences, a process argued to involve the utilization of the working memory system. In both Experiments 2 and 3 there was an anxiety-related performance deficit. The results are consistent with a working memory-oriented account of anxiety-related performance effects, as deficits were restricted to capacity-demanding tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nature of HLA-associated predisposition to childhood acute lymphoblastic leukemia

A molecular analysis was carried out in 63 sequentially diagnosed childhood acute lymphoblastic leukemia (ALL) patients and 1011 controls to investigate the homozygosity rate for HLA-DR53. HLA-DR53 is associated with acute myeloblastic leukemia at the protein level, and our previous study has shown its association with early-onset chronic myeloid leukemia only in homozygous form at the DNA level. In the present study, the homozygosity rates for DR53 were 17.5 and 13.6% in patients and controls, respectively. Ten of the 11 homozygous patients were boys. In the common ALL group (n = 40), all seven DR53 homozygous patients were boys, and among 19 girls this genotype was not observed (P = 0.006). For males, homozygosity for DR53 revealed a relative risk (RR) of 3.29 (P = 0.008) for common ALL. Five of the 11 relapsed patients were homozygous for DR53. Heterozygous frequencies for HLA-DR53 were not different between patients and controls. Homozygosity for DR53 was associated with a very high relapse rate (45.5 vs 7.7%, P = 0.002, RR = 9.1). These results extended our findings in chronic myeloid leukemia and showed the recessive nature and the male predominance of the interactive HLA influence on the development of childhood leukemia. Molecular mimicry of an HLA-DR53 epitope by oncogenic (retro)viruses or putative susceptibility genes in linkage disequilibrium with HLA-DR53 may be responsible for this association.     

Antimicrobial and Anticancer Properties of Synthetic Peptides Derived from the Wasp Parachartergus fraternus

Agelaia-MPI and protonectin are antimicrobial peptides isolated from the wasp Parachartergus fraternus that show antimicrobial and neuroactive activities. Previously, two analogues of these peptides, neuroVAL and protonectin-F, were designed to reduce nonspecific toxicity and improve potency. Here, the three-dimensional structures of neuroVAL, protonectin and protonectin-F were determined by using circular dichroism and NMR spectroscopy. Antibacterial, antifungal, cytotoxic and hemolytic activities were tested for the parent peptides and analogues. All peptides showed moderate antimicrobial activity against Gram-positive bacteria, with agelaia-MPI being the most active. Protonectin and protonectin-F were found to be toxic to cancerous and noncancerous cell lines. Internalization experiments revealed that these peptides accumulate inside both cell types. By contrast, neuroVAL was nontoxic to all tested cells and was able to enter cells without accumulating. In summary, neuroVAL has potential as a nontoxic cell-penetrating peptide, while protonectin-F needs further modification to realize its potential as an antitumor peptide.