Sustained Neutron Production from a Sheared-Flow Stabilized Z Pinch

The sheared-flow stabilized Z pinch has demonstrated long-lived plasmas with fusion-relevant parameters. We present the first experimental results demonstrating sustained, quasi-steady-state neutron production from the fusion Z-pinch experiment, operated with a mixture of 20% deuterium/80% hydrogen by pressure. Neutron emissions lasting approximately 5  μs are reproducibly observed with pinch currents of approximately 200 kA during an approximately 16  μs period of plasma quiescence. The average neutron yield is estimated to be (1.25±0.45)×10^{5}  neutrons/pulse and scales with the square of the deuterium concentration. Coincident with the neutron signal, plasma temperatures of 1-2 keV and densities of approximately 10^{17}  cm^{-3} with 0.3 cm pinch radii are measured with fully integrated diagnostics.

Interferon-α induces negative biases in emotional processing in patients with hepatitis C virus infection: a preliminary study

BACKGROUND

Treatment of medical patients with the inflammatory cytokine, interferon-α (IFN-α), is frequently associated with the development of clinical depressive symptomatology. Several important biological correlates of the effect of IFN-α on mood have been described, but the neuropsychological changes associated with IFN-α treatment are largely unexplored. The aim of the present preliminary study was to assess the effect of IFN-α on measures of emotional processing.

METHOD

We measured changes in emotional processing over 6-8 weeks in 17 patients receiving IFN-α as part of their treatment for hepatitis C virus infection. Emotional processing tasks included those which have previously been shown to be sensitive to the effects of depression and antidepressant treatment, namely facial expression recognition, emotional categorisation and the dot probe attentional task.

RESULTS

Following IFN-α, patients were more accurate at detecting facial expressions of disgust; they also showed diminished attentional vigilance to happy faces. IFN-α produced the expected increases in scores on depression rating scales, but there was no correlation between these scores and the changes in emotional processing.

CONCLUSIONS

Our preliminary findings suggest that IFN-α treatment produces negative biases in emotional processing, and this effect is not simply a consequence of depression. It is possible that increased recognition of disgust may represent a neuropsychological marker of depressive disorders related to inflammation.

Spatiotemporal Evolution of Runaway Electron Momentum Distributions in Tokamaks

Novel spatial, temporal, and energetically resolved measurements of bremsstrahlung hard-x-ray (HXR) emission from runaway electron (RE) populations in tokamaks reveal nonmonotonic RE distribution functions whose properties depend on the interplay of electric field acceleration with collisional and synchrotron damping. Measurements are consistent with theoretical predictions of momentum-space attractors that accumulate runaway electrons. RE distribution functions are measured to shift to a higher energy when the synchrotron force is reduced by decreasing the toroidal magnetic field strength. Increasing the collisional damping by increasing the electron density (at a fixed magnetic and electric field) reduces the energy of the nonmonotonic feature and reduces the HXR growth rate at all energies. Higher-energy HXR growth rates extrapolate to zero at the expected threshold electric field for RE sustainment, while low-energy REs are anomalously lost. The compilation of HXR emission from different sight lines into the plasma yields energy and pitch-angle-resolved RE distributions and demonstrates increasing pitch-angle and radial gradients with energy.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Gamma ray imager on the DIII-D tokamak

A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1-60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

Consensus guidelines for optimising antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy, 2014

Antifungal agents may be associated with significant toxicity or drug interactions leading to sub-therapeutic antifungal drug concentrations and poorer clinical outcomes for patients with haematological malignancy. These risks may be minimised by clinical assessment, laboratory monitoring, avoidance of particular drug combinations and dose modification. Specific measures, such as the optimal timing of oral drug administration in relation to meals, use of pre-hydration and electrolyte supplementation may also be required. Therapeutic drug monitoring (TDM) of antifungal agents is warranted, especially where non-compliance, non-linear pharmacokinetics, inadequate absorption, a narrow therapeutic window, suspected drug interaction or unexpected toxicity are encountered. Recommended indications for voriconazole and posaconazole TDM in the clinical management of haematology patients are provided. With emerging knowledge regarding the impact of pharmacogenomics upon metabolism of azole agents (particularly voriconazole), potential applications of pharmacogenomic evaluation to clinical practice are proposed.

Diazinon and permethrin mitigation across a grass-wetland buffer

Vegetated buffers of different designs are often used as edge-of-field treatment practices to remove pesticides that may be entrained in agricultural runoff. However, buffer system efficacy in pesticide runoff mitigation varies widely due to a multitude of factors including, but not limited to, pesticide chemistry, vegetation composition, and hydrology. Two experimental systems, a control (no vegetation) and a grass-wetland buffer system, were evaluated for their ability to retain diazinon and permethrin associated with a simulated storm runoff. The two systems were equally inefficient at retaining diazinon (mean 9.6 % retention for control and buffer). Grass-wetland buffers retained 83 % and 85 % of cis- and trans-permethrin masses, respectively, while the control only retained 39 % and 44 % of cis- and trans-permethrin masses, respectively. Half-distances (the distance required to decrease pesticide concentration by one-half) for both permethrin isomers were 26 %-30 % shorter in grass buffers (22-23 m) than in the control (32 m). The current study demonstrates treatment efficacy was a function of pesticide properties with the more strongly sorbing permethrin retained to a greater degree. The study also demonstrates challenges in remediating multiple pesticides with a single management practice. By using suites of management practices, especially those employing vegetation, better mitigation of pesticide impacts may be accomplished.

Variability in the characterization of total coliforms, fecal coliforms and Escherichia coli in recreational water supplies of north Mississippi, USA

The fecal coliform, Escherichia coli, is a historical organism for the detection of fecal pollution in water supplies. The presence of E. coli indicates a potential contamination of the water supply by other more hazardous human pathogens. In order to accurately determine the presence and degree of fecal contamination, it is important that standard methods approved by the US Environmental Protection Agency are designed to determine the presence of E. coli in a water supply, and distinguish E. coli from other coliform bacteria (e.g. Citrobacter, Klebsiella and Enterobacter). These genera of bacteria are present not only in fecal matter, but also in soil and runoff water and are not good indicators of fecal contamination. There is also ambiguity in determining a positive result for fecal coliforms on M-FC filters by a blue colony. When all variations of blue, including light blue or glossy blue, were examined, confirmation methods agreed with the positive M-FC result less often than when colonies that the technician would merely call "blue", with no descriptors, were examined. Approximately 48 % of M-FC positive colonies were found to be E. coli with 4 methylumbelliferyl-β-D-glucuronide (MUG), and only 23 % of samples producing a positive result on M-FC media were found to be E. coli using API-20E test strips and current API-20E profiles. The majority of other M-FC blue colonies were found to be Klebsiella or were unidentifiable with current API-20E profiles. Two positive M-FC colonies were found to be Kluyvera with API-20E, both of which cleaved MUG and produced fluorescence under UV light, a characteristic used to differentiate E. coli from other fecal coliforms.

Abstract P5-11-08: SRA/SRAP contributes to TGF-b1 induced cell motility in cancer cells

The steroid receptor RNA activator gene (SRA1) is a particularly intriguing genetic system in that both the corresponding RNA (SRA) and protein (SRAP) have been proven to be functional. Accumulated evidence overall suggests that both molecules act as distinct co-regulators of transcription, housed in ribonucleo-protein complexes able to positively or negatively regulate the activity of multiple transcription factors including -but not limited to- several nuclear receptors, MyoD and DAX-1.

A role for SRA/SRAP deregulation during breast tumorigenesis has been suggested. Indeed, not only do these molecules regulate the activity of both Estrogen Receptors, these major players in breast cancer etiology, but it has also been shown that SRA RNA is more highly expressed in breast tumors than in normal tissue, and that high levels of SRAP correlated to poorer survival in specific subsets of breast cancer patients.

In order to identify the genes and pathways regulated by SRA/SRAP, we performed deep sequencing of transcriptomes from MDA-MB-231 cells depleted of these molecules following RNA interference. The expression of 149 genes was consistently and significantly altered in four independent experiments comparing control RNAi vs SRA RNAi. Interestingly, cluster analysis using Ingenuity software defined a subset of genes (23 out of 149) directly associated with cell movement. Among them figured TGFBR1 (ALK5), a cell surface receptor-kinase mediating TGF-b signalling and a known promoter of cell motility in breast cancer cells.

We have now confirmed by quantitative PCR analysis a 40% decrease, upon SRA/SRAP depletion, of TGFBR1 mRNA expression in MDA-MB-231 cells as well as in other breast (MCF7, T5) and non-breast (Hela) cancer cell lines. Consistent with this decrease a drop to 60% of the basal TGFBR1 protein expression is seen by Western blot when MDA-MB-231 cells are depleted of SRA/SRAP. Western blot analyses also revealed that phosphorylation of several SMAD molecules, downstream effectors of TGFBR1 activation by TGF-β1, is impaired in the absence of SRA/SRAP in both MDA-MB-231 and Hela cells. This suggests that SRA/SRAP could potentially regulate TGF beta induced cell motility.

Using migration cell assays, we have now confirmed that upon TGF-β1 treatment for 6 hours, SRA/SRAP depleted cells had a significant decrease in migration as compared to control cells. Accordingly, live cell migration assays generated by a time-lapse videomicroscopy system, showed an increased track length and speed in both Hela and 231 cells over-expressed SRAP upon 10 h TGF-β1 treatment.

Taken together, these data suggest a cross-talk between SRA/SRAP and TGF-β signalling and induced cell motility.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-11-08.

Fast dynamos in spherical boundary-driven flows

We numerically demonstrate the feasibility of kinematic fast dynamos for a class of time-periodic axisymmetric flows of conducting fluid confined inside a sphere. The novelty of our work is in considering the realistic flows, which are self-consistently determined from the Navier-Stokes equation with specified boundary driving. Such flows can be achieved in a new plasma experiment, whose spherical boundary is capable of differential driving of plasma flows in the azimuthal direction. We show that magnetic fields are self-excited over a range of flow parameters such as amplitude and frequency of flow oscillations, fluid Reynolds (Re) and magnetic Reynolds (Rm) numbers. In the limit of large Rm, the growth rates of the excited magnetic fields are of the order of the advective time scales and practically independent of Rm, which is an indication of the fast dynamo.

Termination of a magnetized plasma on a neutral gas: the end of the plasma

Experiments are performed at the Enormous Toroidal Plasma Device at UCLA to study the neutral boundary layer (NBL) between a magnetized plasma and a neutral gas along the direction of a confining magnetic field. This is the first experiment to measure plasma termination within a neutral gas without the presence of a wall or obstacle. A magnetized, current-free helium plasma created by a lanthanum hexaboride (LaB6) cathode terminates entirely within a neutral helium gas. The plasma is weakly ionized (ne/nn∼1%) and collisional λn≪Lplasma}. The NBL occurs where the plasma pressure equilibrates with the neutral gas pressure, consistent with a pressure balance model. It is characterized by a field-aligned ambipolar electric field, developing self-consistently to maintain a current-free termination of the plasma on the neutral gas. Probes are inserted into the plasma to measure the plasma density, flow, temperature, current, and potential. These measurements confirm the presence of the ambipolar field and the pressure equilibration model of the NBL.

A new large area lanthanum hexaboride plasma source

A new 18x18 cm(2) active area lanthanum hexaboride (LaB(6)) plasma source for use in a dc discharge has been developed at UCLA. The cathode consists of four tiled LaB(6) pieces indirectly heated to electron emission (1750 degrees C) by a graphite heater. A molybdenum mesh anode 33 cm in front of the LaB(6) accelerates the electrons, ionizing a fill gas to create a 20x20 cm(2) nearly square plasma. The source is run in pulsed operation with the anode biased up to +400 V dc with respect to the cathode for up to 100 ms at a 1 Hz repetition rate. Both the cathode and anode "float" electrically with respect to the chamber walls. The source is placed in a toroidal chamber 2 m wide and 3 m tall with a major radius of 5 m. Toroidal and vertical magnetic fields confine the current-free plasma which follows the field in a helix. The plasma starts on the bottom of the machine and spirals around it up to four times (120 m) and can be configured to terminate either on the top wall or on the neutral gas itself. The source typically operates with a discharge current up to 250 A in helium making plasmas with T(e)<30 eV, T(i)<16 eV, and n(e)<3x10(13) cm(-3) in a background field of 100 G<B(o)<320 G, giving a magnetized plasma with 0.1<beta<1.

Nutrient mitigation capacity in Mississippi Delta, USA drainage ditches

Eutrophication and hypoxia within aquatic systems are a serious international concern. Various management practices have been proposed to help alleviate nutrient loads transported to the Gulf of Mexico and other high-profile aquatic systems. The current study examined the nutrient mitigation capacity of a vegetated (V) and non-vegetated (NV) agricultural drainage ditch of similar size and landform in the Mississippi Delta. While no statistically significant differences in ammonium, nitrate, or dissolved inorganic phosphorus mitigation between the two ditches existed, there were significant differences in total inorganic phosphorus percent load reductions (V: 36% +/- 4; NV: 71% +/- 4). However, both agricultural drainage ditches were able to mitigate nutrients, thus reducing the load reaching downstream aquatic receiving systems. Further studies examining ecosystem dynamics within drainage ditches such as sediment and plant nutrient partitioning, as well as microbial processes involved, are needed to provide a better understanding of natural nutrient variability, seasonality and flux.

Ability of four emergent macrophytes to remediate permethrin in mesocosm experiments

Increased focus is being placed on the ability of native vegetation to mitigate potential harmful effects of agricultural runoff, especially pyrethroid insecticides. Replicate 379 L Rubbermaid tubs (1.25 m [l] x 0.6 m [w] x 0.8 m [h]) were planted with individual species of cutgrass (Leersia oryzoides), cattails (Typha latifolia), bur-reed (Sparganium americanum), and powdery alligator-flag (Thalia dealbata), all common wetland macrophytes found in the Mississippi Delta, USA, agricultural region. Permethrin-enriched water (target concentration, 5 microg L(-1)) was pumped in at a 4-h hydraulic retention time at one end of the tub and discharged at the far end. Water samples were collected from discharge at 1-h intervals for 12 h and analyzed for permethrin concentrations. Permethrin removal rates were compared for the four different plant treatments and nonvegetated sediment-water controls. Results indicated that no particular single plant species was more effective at removing permethrin in water relative to unplanted controls. Overall mass reductions (from inflow to outflow) for cis-permethrin ranged from 67% +/- 6% in T. latifolia to 71% +/- 2% in L. oryzoides. The trans-permethrin overall mass reductions ranged from 76% +/- 4% in S. americanum to 82% +/- 2% in the unplanted control. Sediment and plant samples collected at the study conclusion indicated that 77%-95% of measured permethrin mass was associated with sediment for mesocosms planted with L. oryzoides, T. latifolia, and T. dealbata. Conversely, mesocosms planted with S. americanum had 83% of measured mass associated with the plant material. Specific plant-pesticide retention studies can lead to improved planning for best management practices and remediation techniques such as constructed wetlands and vegetated agricultural drainage ditches.

Mitigation of two pyrethroid insecticides in a Mississippi Delta constructed wetland

Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m), comprising a sediment retention basin and two treatment cells, was used to determine the fate and transport of simulated runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results showed 49 and 76% of the study's measured lambda-cyhalothrin and cyfluthrin masses were associated with vegetation, respectively. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing area. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides.

Considerations for assessments of wadable drainage systems in the agriculturally dominated deltas of Arkansas and Mississippi

The watershed approach, currently used to assess regional streams in the United States, emphasizes least-disturbed reference conditions. Consideration of extensive wadable drainage systems found in Arkansas and Mississippi deltas challenges concepts of disturbance within a landscape of historic agricultural land use. Seventeen wadable drainage ditch sites in Arkansas and Mississippi deltas were characterized using water quality parameters and rapid bioassessment protocols. In all, 19 fish and 105 macroinvertebrate taxa were identified. Macroinvertebrate assemblages were dominated by coleopteran, dipteran, and hemipteran taxa at most drainage sites. Predominance of mobile, early colonists in ditches limits applicability of some metrics for assessment of stream integrity beyond prevalent conditions of ephemeral water quantity and habitat maintenance. This study provides evidence of considerable variability of physical characteristics, water quality, and fish and invertebrate metrics in wadable drainage systems. It indicates a disparity in usefulness of the watershed approach, emphasizing least-disturbed reference conditions, in assessing ecological integrity for a region with ditches as dominant landscape features.

Mitigation assessment of vegetated drainage ditches for collecting irrigation runoff in California

Widespread contamination of California water bodies by the organophosphate insecticides diazinon and chlorpyrifos is well documented. While their usage has decreased over the last few years, a concomitant increase in pyrethroid usage (e.g., permethrin) (replacement insecticides) has occurred. Vegetated agricultural drainage ditches (VADD) have been proposed as a potential economical and environmentally efficient management practice to mitigate the effects of pesticides in irrigation and storm runoff. Three ditches were constructed in Yolo County, California for a field trial. A U-shaped vegetated ditch, a V-shaped vegetated ditch, and a V-shaped unvegetated ditch were each amended for 8 h with a mixture of diazinon, permethrin, and suspended sediment simulating an irrigation runoff event. Water, sediment, and plant samples were collected spatially and temporally and analyzed for diazinon and permethrin concentrations. Pesticide half-lives were similar between ditches and pesticides, ranging from 2.4 to 6.4 h. Differences in half-distances (distance required to reduce initial pesticide concentration by 50%) among pesticides and ditches were present, indicating importance of vegetation in mitigation. Cis-permethrin half-distances in V ditches ranged from 22 m (V-vegetated) to 50 m (V-unvegetated). Half-distances for trans-permethrin were similar, ranging from 21 m (V-vegetated) to 55 m (V-unvegetated). Diazinon half-distances demonstrated the greatest differences (55 m for V-vegetated and 158 m for V-unvegetated). Such economical and environmentally successful management practices will offer farmers, ranchers, and landowners a viable alternative to more conventional (and sometimes expensive) practices.

Agricultural drainage ditches mitigate phosphorus loads as a function of hydrological variability

Phosphorus (P) loading from nonpoint sources, such as agricultural landscapes, contributes to downstream aquatic ecosystem degradation. Specifically, within the Mississippi watershed, enriched runoff contributions have far-reaching consequences for coastal water eutrophication and Gulf of Mexico hypoxia. Through storm events, the P mitigation capacity of agricultural drainage ditches under no-till cotton was determined for natural and variable rainfall conditions in north Mississippi. Over 2 yr, two experimental ditches were sampled monthly for total inorganic P concentrations in baseflow and on an event-driven basis for stormflows. Phosphorus concentrations, Manning's equations with a range of roughness coefficients for changes in vegetative densities within the ditches, and discharge volumes from Natural Resources Conservation Service dimensionless hydrographs combined to determine ranges in maximum and outflow storm P loads from the farms. Baseflow regressions and percentage reductions with P concentrations illustrated that the ditches alternated between being a sink and source for dissolved inorganic P and particulate P concentrations throughout the year. Storm event loads resulted in 5.5% of the annual applied fertilizer to be transported into the drainage ditches. The ditches annually reduced 43.92 +/- 3.12% of the maximum inorganic effluent P load before receiving waters. Agricultural drainage ditches exhibited a fair potential for P mitigation and thus warrant future work on controlled drainage to improve mitigation capacity.

Hydrological variability and agricultural drainage ditch inorganic nitrogen reduction capacity

The application of inorganic nitrogen fertilizers on agricultural landscapes has the potential to generate concerns of environmental degradation at fine to coarse scales across the catchment and landscape. Inorganic nitrogen species (NO3*, NO2*, and NH3) are typically associated with subsurface flow processes; however, surface runoff from rainfall events in no-till agriculture with inorganic surface fertilizers might contribute to downstream eutrophication. Inorganic nitrogen reduction capacity of agricultural drainage ditches under no-till cotton was determined under natural, variable rainfall conditions in northern Mississippi. Monthly grab baseflow samples and storm-generated flow samples were variably sampled temporally within two experimental farm ditches over 2 yr. Inorganic nitrogen concentrations, in conjunction with Manning's equation and Natural Resources Conservation Service dimensionless hydrographs, provided individual water volumes per storm event and thus maximum effluent and outflow nitrogen loads. Base and stormflow regression results indicate drainage ditches reducing NO3* and NH3 over the length of the ditch for growing and dormant seasons. Overall, maximum storm loads of dissolved inorganic nitrogen (DIN) from the farm over the 2-yr sampling period accounted for 2.2% of the initial fertilizer application, of which 1.1% left the ditch (0.84 kg ha(-1) yr(-1)) (a 57% ditch reduction of DIN load over 2 yr). Long-term sampling incorporating data on application and loss of fertilizers and farm management will provide critical information for farmers and scientists on the potential of economic gains and downstream ecosystem eutrophication, respectively.

Assessment of diazinon toxicity in sediment and water of constructed wetlands using deployed Corbicula fluminea and laboratory testing

Constructed wetlands for mitigation of nonpoint agricultural runoff have been assessed for their ability to decrease potential toxicity from associated contaminants. After a simulated runoff event, constructed wetlands positioned in series were used to measure the effects of the organophosphate insecticide diazinon. Water, sediment, and plant samples from five sites were analyzed for diazinon concentrations from 0.5 hours to 26 days; peak concentrations were measured in sediment after 0.5 hours (268.7 microg/kg) and in water and plant tissue after 3 hours (121.71 microg/L and 300.7 microg/kg, respectively). Cholinesterase activity and changes in shell growth were measured from Corbicula fluminea deployed at corresponding sites. Water collected after 9 hours from all wetland sites contained diazinon concentrations sufficient to cause toxicity to Ceriodaphnia dubia, but not to Pimephales promelas. C. dubia survival was decreased in water sampled through 7 days from the site nearest runoff introduction, whereas C. fluminea deployed at this same site experienced 100% mortality after 26 days. Clams from lower sites survived wetland conditions, but growth and ChE activity were significantly decreased lower than that of clams from a control site. C. dubia exposed to water from these sites continued to have decreased survival throughout the 26-day sampling. Sediment sampled from 48 hours through 14 days at the lowest wetland site decreased the laboratory survival of Chironomus dilutus, and sediment from upper sites elicited an effect only on day 26. Although wetland concentrations of aqueous diazinon were decreased lower than toxic thresholds after 26 days, decreased ChE activity in deployed clams provided evidence of residual diazinon effects to deployed organisms.

Assessment of pesticide contamination in three Mississippi Delta oxbow lakes using Hyalella azteca

Three oxbow lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, lambda-cyhalothrin, chlorfenapyr, and pp'DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present.

Hydroponic uptake of atrazine and lambda-cyhalothrin in Juncus effusus and Ludwigia peploides

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to changes in soil geochemistry and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Influence of vegetation in mitigation of methyl parathion runoff

A pesticide runoff event was simulated on two 10 m x 50 m constructed wetlands (one non-vegetated, one vegetated) to evaluate the fate of methyl parathion (MeP) (Penncap-M). Water, sediment, and plant samples were collected at five sites downstream of the inflow for 120 d. Semi-permeable membrane devices (SPMDs) were deployed at each wetland outflow to determine exiting pesticide load. MeP was detected in water at all locations of the non-vegetated wetland (50 m), 30 min post-exposure. MeP was detected 20 m from the vegetated wetland inflow 30 min post-exposure, while after 10d it was detected only at 10 m. MeP was measured only in SPMDs deployed in non-vegetated wetland cells, suggesting detectable levels were not present near the vegetated wetland outflow. Furthermore, mass balance calculations indicated vegetated wetlands were more effective in reducing aqueous loadings of MeP introduced into the wetland systems. This demonstrates the importance of vegetation as sorption sites for pesticides in constructed wetlands.

Evaluated fate and effects of atrazine and lambda-cyhalothrin in vegetated and unvegetated microcosms

Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best-management practices. Our research has shown that the presence of macrophytes and a hydrologic regime aid in the transfer and transformation of pesticides associated with agricultural runoff. This study consisted of application of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to vegetated and unvegetated microcosms in order to measure the fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through concentrations of atrazine and lambda-cyhalothrin in plant tissue as high as 2461.4 and 86.50 microg/kg, respectively. Toxicity was measured in water from unvegetated microcosms for 28 days and in Chironomus tentans (midge larvae) exposed to sediment collected from 3 h to 56 days in microcosms receiving the pesticide combination. The comparative survival of test organisms in this study suggests that effective mitigation of pesticides from runoff can depend on the macrophyte contact and vegetative attributes associated with ditches.

Vegetative and structural characteristics of agricultural drainages in the Mississippi Delta landscapes

Agricultural drainage ditches in the Mississippi Alluvial Delta landscape vary from edge-of-field waterways to sizeable drainages. Ditch attributes vary with size, location and maintenance and may aid in mitigation of contaminants from agricultural fields. The goal of this study was to better understand how vegetative characteristics affect water quality in conveyance structures in the context of ditch class and surrounding land use. Characterization of 36 agricultural ditches included presence of riparian buffer strips, water depth, surrounding land use, vegetative cover, and associated aqueous physicochemical parameters. Vegetation was assessed quantitatively, obtaining stem counts in a sub-sample of ditch sites, using random quadrat method. Physical features varied with ditch size and vegetative diversity was higher in larger structures. Polygonum sp. was the dominant bed vegetation and was ubiquitous among site sizes. Macrophytes varied from aquatic to upland species, and included Leersia sp. and upland grasses (Poaceae family) in all drainage size classes. Percent cover of bed and bank varied from 0 to 100% and 70 to 100%, respectively, and highest nutrient values were measured in sites with no buffer strips. These conveyance structures and surrounding buffer zones are being ranked for their ability to reduce excess nutrients, suspended solids, and pesticides associated with runoff.

Evaluating acute toxicity of methyl parathion application in constructed wetland mesocosms

Wetland ecosystems have reduced ambient levels of various organic and metallic compounds, although their effectiveness on agricultural pesticides is not well documented. Five stations within each of two 10 x 50 m constructed wetlands (two vegetated, two nonvegetated) were selected to measure the fate and effects of methyl parathion (MeP). Following a simulated storm event (0.64 cm of rainfall), aqueous, sediment, and plant samples were collected and analyzed spatially (5, 10, 20, and 40 m from the inlet) and temporally (after 3-10 days) for MeP concentrations and for the impact of those concentrations on the aquatic fauna. Aqueous toxicity to fish decreased spatially and temporally in the vegetated mesocosm. Pimephales promelas survival was significantly reduced, to 68%, at the 10-m station of the nonvegetated wetlands (3 h postapplication), with pesticide concentrations averaging 9.6 microg MeP/L. Ceriodaphnia in both the vegetated and nonvegetated wetlands was sensitive (i.e., a significant acute response to MeP occurred) to pesticide concentrations through 10 days postapplication. Mean MeP concentrations in water ranged from 0.5 to 15.4 microg/L and from 0.1 to 27.0 microg/L in the vegetated and nonvegetated wetlands, respectively. Hyalella azteca aqueous tests resulted in significant mortality in the 5-m vegetated segment 10 days after exposure to MeP (2.2 microg/L). Solid-phase (10-day) sediment toxicity tests showed no significant reduction in Chironomus tentans survival or growth, except for the sediments sampled 3 h postapplication in the nonvegetated wetland (65% survival). Thereafter, midge survival averaged >87% in sediments sampled from both wetlands. These data suggest that wetlands play a significant role in mitigating the effect of MeP exposure in sensitive aquatic biota.

Evaluating toxicity of Asana XL (esfenvalerate) amendments in agricultural ditch mesocosms

Agricultural ditches primarily serve to remove and store excess water associated with irrigation and storm events. The ability of these ecosystems to mitigate potential contaminants is not well understood. Five sites along a 650-m agricultural ditch located in the Mississippi Delta Management Systems Evaluation Area (MDMSEA) were used to measure fate and effects of an esfenvalerate (insecticide) exposure. Following a 0.64-cm simulated storm event, samples were collected from water and sediments and analyzed spatially from five sites and temporally from 0.5 h to 56 d. Results of aqueous toxicity bioassays indicated that lethality progressed downstream throughout all sampling intervals, while sediment toxicity bioassays only elicited biological responses at the point of pesticide application to the ditch (0 m). Significant reductions in survival of Ceriodaphnia dubia and Pimephales promelas in water were measured at the 0-, 20-, and 80-m sites following application. Ten-day solid phase sediment testing of Chironomus tentans indicated persistent toxicity only at the point of application (0 m) and throughout 56 d (mean=14.4% survival). No lethality or significant reduction in midge growth was measured for remaining downstream sites. These measurements were used to evaluate the potential of agricultural ditches to reduce potential deleterious effects of contaminants in agricultural drainage systems that precede receiving streams.

Innovative uses of vegetated drainage ditches for reducing agricultural runoff

Vegetated agricultural ditches play an important role in mitigation of pesticides following irrigation and storm runoff events. In a simulated runoff event in the Mississippi (USA) Delta, the mitigation capacity of a drainage ditch using the pyrethroid esfenvalerate (Asana XL) was evaluated. The pesticide was amended to soil prior to the runoff event to simulate actual runoff, ensuring the presence of esfenvalerate in both water and suspended particulate phases. Water, sediment, and plant samples were collected temporally and spatially along the drainage ditch. Even with mixing of the pesticide with soil before application, approximately 99% of measured esfenvalerate was associated with ditch vegetation (Ludwigia peploides, Polygonum amphibium, and Leersia oryzoides) three hours following event initiation. This trend continued for the 112 d study duration. Simple modeling results also suggest that aqueous concentrations of esfenvalerate could be mitigated to 0.1% of the initial exposure concentration within 510 m of a vegetated ditch. Observed field half-lives in water, sediment, and plant were 0.12 d, 9 d, and 1.3 d, respectively. These results validate the role vegetation plays in the mitigation of pesticides, and that ditches are an indispensable component of the agricultural production landscape.

Acute toxicity of methyl-parathion in wetland mesocosms: assessing the influence of aquatic plants using laboratory testing with Hyalella azteca

Methyl-parathion (MeP) was introduced into constructed wetlands for the purpose of assessing the importance of distance from the source of contamination and the role of emergent vegetation on the acute toxicity to Hyalella azteca (Crustacea: Amphipoda). A vegetated (90% cover: mainly Juncus effuses) and a nonvegetated wetland (each with a water body of 50 x 5.5 x 0.2 m) were each exposed to a simulated MeP storm runoff event. H. azteca was exposed for 48 h in the laboratory to water samples taken from the wetlands at a distance of 5, 10, 20, and 40 m from the pesticide inlet 3 h, 24 h, 96 h, and 10 days following application. Methyl-parathion was detected throughout the nonvegetated wetland, whereas the pesticide was only transported halfway through the vegetated wetland. A repeated-measure three-way analysis of variance (ANOVA) using time, location, and vegetation indicated significantly lower toxicity in the vegetated wetland. Furthermore, the mortality decreased significantly with both increasing distance from the inlet and time (48-h LC50 +/- 95% CI: 9.0 +/- 0.3 microg/L). A significant three-way interaction of time x vegetation x location confirmed higher toxicity at the inlet area of the nonvegetated wetland immediately after contamination. Significant linear regressions of maximum mortality (independent of time) versus distance from the pesticide inlet indicated that 44 m of vegetated and 111 m of nonvegetated wetland would reduce H. azteca mortality to < or = 5%. These results suggest that vegetation contributes to reduced MeP effects in constructed wetlands.

Mitigation of chlorpyrifos runoff using constructed wetlands

Constructed wetlands have been proposed as a potential best management practice (BMP) to mitigate effects of pesticide-associated agricultural runoff. Wetland mesocosms (14 m x 59-73 m) were amended with chlorpyrifos to simulate a storm runoff event at concentrations of 73, 147 and 733 microg/l. Water, sediment and plant samples collected weekly for 12 weeks indicated that chlorpyrifos rapidly sorbed to sediment and plant material, with approximately 47-65% of measured chlorpyrifos mass retained within the first 30-36 m of wetland mesocosms. Of the measured mass, approximately 55% and 25% were retained by sediments and plants, respectively. A field-scale evaluation of a constructed wetland's mitigation capability was performed in the Lourens River watershed of Cape Town, South Africa. Results indicate that the wetland was able to retain and considerably decrease the concentration (and hence toxicity) of chlorpyrifos and suspended sediment entering the receiving waterbody (Lourens River). This research provides fundamental answers concerning constructed wetland capabilities that are necessary for constructing field-scale systems within agricultural watersheds.

The anaesthetic management of a case of severe upper airways obstruction due to an enlarging subglottic benign polyp

The use of a newly developed aid to jet ventilation of the lungs, a modified Ben-Jet tube (the Hunsaker Monjet tube), is described in a patient with partial upper airway obstruction. This report highlights an unusual use of this device. The Monjet is a fluoroplastic, monitored, self-centring, fine bore tube that can be inserted from the mouth through to the subglottic region. It was originally developed to anaesthetize healthy patients without airway obstruction who were undergoing suspension microlaryngoscopy.

Dynamics of diffuse pollution from US southern watersheds

To understand the effects of diffuse pollution information on the source of pollutants, quantities in transport, mode of transport, transient nature of the pollution event, and most importantly, a consideration of remediation efforts need to be known. For example, water quality research in the Yazoo Basin uplands in Mississippi has shown sediment loads from a conventional-till upland soybean watershed to be about 19,000kg/ha/yr, and responsible for 77-96% of P and N in transport. In contrast, sediment loads from a comparable no-till soybean watershed were only 500 kg/ha/yr. transporting about 31% of P and N in transport. Sediment loads from a nearby forested area were low, about 200 kg/ha/yr, but responsible for about 47-76% of P and N in transport. Transient pollution events are responsible for the transport of large quantities of sediment, nutrients, and pesticides; in some storm events nearly the annual load. Best management practices (BMPs) must be designed to remediate diffuse pollution and the transient nature of pollution events which can have a profound effect on the ecological health of steams and reservoirs.

Arsenic and mercury concentrations in major landscape components of an intensively cultivated watershed

To provide an understanding of arsenic (As) and mercury (Hg) concentrations in soil, sediment, water, and fish tissues, samples were collected from a Mississippi River alluvial floodplain located in northwest Mississippi. As concentrations increased approximately an order of magnitude from water (5.12 micrograms/l) to fish tissues (36.99 micrograms/kg) and an additional two orders of magnitude in soils, lake sediments, and wetland sediments (5728, 5614, and 6746 micrograms/kg), respectively. Average Hg concentrations in water, soils, lake sediments, and fish were 2.16 micrograms/l, 55.1, 14.5 and 125 micrograms/kg, respectively. As and Hg concentrations were within published ranges for uncontaminated soil, water, and sediments. As concentrations represented a low risk. Hg concentrations were also low but showed a greater tendency to concentrate in fish tissue. The dominant mode of entry of these materials into aquatic systems is through storm-generated runoff. Since both metals accompany sediments, agricultural conservation practices such as reduced tillage, buffer riparian strips, and bordering sediment ponds or drainage wetlands will minimize watershed input to aquatic systems.

Constructed wetlands for mitigation of atrazine-associated agricultural runoff

Atrazine was amended into constructed wetlands (59-73x14x0.3 m) for the purpose of monitoring transport and fate of the pesticide to obtain information necessary to provide future design parameters for constructed wetlands mitigation of agricultural runoff. Following pesticide amendment, a simulated storm and runoff event equal to three volume additions was imposed on each wetland. Targeted atrazine concentrations were 0 microg/l (unamended control), 73 microg/l, and 147 microg/l. Water, sediment, and plant samples were collected weekly for 35 days from transects longitudinally distributed throughout each wetland and were analyzed for atrazine using gas chromatography. Between 17 and 42% of measured atrazine mass was within the first 30-36 m of wetlands. Atrazine was below detection limits (0.05 microg/kg) in all sediment and plant samples collected throughout the duration of this study. Aqueous half lives ranged from 16 to 48 days. According to these data, conservative buffer travel distances of 100-280 m would be necessary for effective runoff mitigation.

Analysis of neurogenesis and programmed cell death reveals a self-renewing capacity in the adult rat brain

The adult central nervous system was thought to be very limited in its regenerative potential; however, the discovery that stem cell populations produce neurons in the adult brain highlights the dynamics of a previously assumed 'static' organ. The continuous generation of new neurons in the adult brain, nevertheless, leads to the question of whether neurogenesis is counterbalanced by an accompanying cell death in the same regions. The objective of this study was to stereologically analyze neurogenesis and programmed cell death in adult brain regions with known neurogenic activity. Using bromodeoxyuridine (BrdU) to identify newborn cells we find that within a few days of BrdU-labeling the adult dentate gyrus and olfactory bulb generate high numbers of newborn neurons. More importantly, dUTP-nick end labeling (TUNEL) reveals that areas of adult neurogenesis also contain high numbers of apoptotic cells. We conclude that programmed cell death may have an important regulatory function by eliminating supernumerous cells from neurogenic regions and may thus contribute to a self-renewal mechanism in the adult mammalian brain.

RESEARCH: Warmwater Stream Bank Protection and Fish Habitat: A Comparative Study

/ Fishes and their habitats were sampled in Harland Creek, Mississippi, for 3 years to compare the relative value of three types of bank treatment in an incised, warmwater stream. Semiannual samples were collected from 10 reaches: 3 reaches protected by each of the three types of protection (longitudinal stone toe, stone spurs, and dormant willow posts) and an unprotected, slowly eroding bend. Protection of concave banks of bends had no measurable effect on the habitat quality of downstream riffles. Although bends and adjacent downstream riffles were faunistically similar at the species level, catostomids and centrarchids were more dominant in pools and smaller cyprinids more dominant in riffles. Reaches with willow posts were slightly deeper than the others, most likely because of geomorphic factors rather than bank treatment. Mean water surface widths in reaches stabilized with stone spurs were 40% to 90% greater than for other treatments, and current velocities were greatest in reaches with stone toe. Patterns of fish abundance and species diversity did not differ significantly among treatments. However, principal components analysis indicated that the fish species distribution associated with the untreated reference site was distinct. Reaches stabilized with stone spurs supported significantly higher densities of large fish and higher levels of fish biomass per unit channel length than reaches with other bank treatments, generally confirming previous research in the region. Initial costs for spurs were comparable to those for stone toe and about three times greater than for willow posts.

Characterization of plasmin-mediated activation of plasma procarboxypeptidase B. Modulation by glycosaminoglycans

Plasma carboxypeptidase B (PCB) is an exopeptidase that exerts an antifibrinolytic effect by releasing C-terminal Lys and Arg residues from partially degraded fibrin. PCB is produced in plasma via limited proteolysis of the zymogen, pro-PCB. In this report, we show that the K(m) (55 nM) for plasmin-catalyzed activation of pro-PCB is similar to the plasma concentration of pro-PCB (50-70 nM), whereas the K(m) for the thrombin- or thrombin:thrombomodulin-catalyzed reaction is 10-40-fold higher than the pro-PCB level in plasma. Additionally, tissue-type plasminogen activator triggers activation of pro-PCB in blood plasma in a reaction that is stimulated by a neutralizing antibody versus alpha(2)-antiplasmin. Together, these results show that plasmin-mediated activation of pro-PCB can occur in blood plasma. Heparin (UH) and other anionic glycosaminoglycans stimulate pro-PCB activation by plasmin but not by thrombin or thrombin:thrombomodulin. Pro-PCB is a more favorable substrate for plasmin in the presence of UH (16-fold increase in k(cat)/K(m)). UH also stabilizes PCB against spontaneous inactivation. The presence of UH in clots prepared with prothrombin-deficient plasma delays tissue-type plasminogen activator-triggered lysis; this effect of UH on clot lysis is blocked by a PCB inhibitor from potato tubers. These results show that UH accelerates plasmin-catalyzed activation of pro-PCB in plasma and PCB, in turn, stabilizes fibrin against fibrinolysis. We propose that glycosaminoglycans in the subendothelial extracellular matrix serve to augment the levels of PCB activity thereby stabilizing blood clots at sites where there is a breach in the integrity of the vasculature.

Suspected recurrence of malignant hyperthermia after post-extubation shivering in the intensive care unit, 18 h after tonsillectomy

A 25-yr-old man, subsequently shown to be malignant hyperthermia (MH) susceptible by in vitro contracture testing, developed MH during anaesthesia for tonsillectomy. Prompt treatment, including dantrolene, led to rapid resolution of the metabolic crisis. Eighteen hours later the patient's trachea was extubated in the ICU, when he had been stable and apyrexial overnight. Twenty minutes after extubation, an episode of shivering was followed by the onset of tachycardia, hypertension, tachypnoea and a rapid increase in temperature. Recurrence of MH was suspected and the patient was given another dose of dantrolene with good clinical effect. Shivering in this patient may have been an indicator or a causative factor of recurrence of MH.

Selective inhibition of factor Xa in the prothrombinase complex by the carboxyl-terminal domain of antistasin

Studies of antistasin, a potent factor Xa inhibitor with anticoagulant properties, were performed wherein the properties of the full-length antistasin polypeptide (ATS-119) were compared with the properties of forms of antistasin truncated at residue 116 (ATS-116) and residue 112 (ATS-112). ATS-119 was 40-fold more potent than ATS-112 in prolonging the activated partial thromboplastin time (APTT), whereas ATS-119 inhibited factor Xa 2.2-fold less avidly and about 5-fold more slowly than did ATS-112. The decreased reactivity of ATS-119 suggests that the carboxyl-terminal domain of ATS-119 stabilizes an ATS conformation with a reduced reactivity toward factor Xa. The observation that calcium ion increases the reactivity of ATS-119 but not that of ATS-112 suggests that calcium ion may disrupt interactions involving the carboxyl terminus of ATS-119. Interestingly, ATS-119 inhibited factor Xa in the prothrombinase complex 2-6-fold more potently and 2-3-fold faster than ATS-112. These differences in affinity and reactivity might well account for the greater effectiveness of ATS-119 in prolonging the APTT and suggest that the carboxyl-terminal domain of ATS-119 disrupts interactions involving phospholipid, factor Va, and prothrombin in the prothrombinase complex. The peptide RPKRKLIPRLS, corresponding to the carboxyl domain of ATS-119 prolonged the APTT and inhibited prothrombinase-catalyzed processing of prothrombin, but it failed to inhibit the catalytic activity of isolated factor Xa. Thus, this novel inhibitor appears to exert its inhibitory effects at a site removed from the active site of factor Xa.

Efficacious, orally bioavailable thrombin inhibitors based on 3-aminopyridinone or 3-aminopyrazinone acetamide peptidomimetic templates

We have addressed the key deficiency of noncovalent pyridinone acetamide thrombin inhibitor L-374,087 (1), namely, its modest half-lives in animals, by making a chemically stable 3-alkylaminopyrazinone bioisostere for its 3-sulfonylaminopyridinone core. Compound 3 (L-375,378), the closest aminopyrazinone analogue of 1, has comparable selectivity and slightly decreased efficacy but significantly improved pharmacokinetics in rats, dogs, and monkeys to 1. We have developed an efficient and versatile synthesis of 3, and this compound has been chosen for further preclinical and clinical development.