An evaluation of conventional and nature-based technologies for controlling antibiotic-resistant bacteria and antibiotic-resistant genes in wastewater treatment plants

Antibiotic resistance is a globally recognized health concern which leads to longer hospital stays, increased morbidity, increased mortality, and higher medical costs. Understanding how antibiotic resistance persists and exchanges in environmental systems like soil, water, and wastewater are critically important for understanding the emergence of pathogens with new resistance profiles and the subsequent exposure of people who indirectly/directly come in contact with these pathogens. There are concerns about the widespread application of prophylactic antibiotics in the clinical and agriculture sectors, as well as chemicals/detergents used in food and manufacturing industries, especially the quaternary ammonium compounds which have been found responsible for the generation of resistant genes in water and soil. The rates of horizontal gene transfer increase where there is a lack of proper water/wastewater infrastructure, high antibiotic manufacturing industries, or endpoint users - such as hospitals and intensive agriculture. Conventional wastewater treatment technologies are often inefficient in the reduction of ARB/ARGs and provide the perfect combination of conditions for the development of antibiotic resistance. The wastewater discharged from municipal facilities may therefore be enriched with bacterial communities/pathogens and provide a suitable environment (due to the presence of nutrients and other pollutants) to enhance the transfer of antibiotic resistance. However, facilities with tertiary treatment (either traditional/emerging technologies) provide higher rates of reduction. This review provides a synthesis of the current understanding of wastewater treatment and antibiotic resistance, examining the drivers that may accelerate their possible transmission to a different environment, and highlighting the need for tertiary technologies used in treatment plants for the reduction of resistant bacteria/genes.

Efficiency of charge transfer in changing the dissociation dynamics of OD+ transients formed after the photo-fragmentation of D2O

We present an investigation of the relaxation dynamics of deuterated water molecules after direct photo-double ionization at 61 eV. We focus on the very rare D+ + O+ + D reaction channel in which the sequential fragmentation mechanisms were found to dominate the dynamics. Aided by theory, the state-selective formation and breakup of the transient OD+(a1Δ, b1Σ+) is traced, and the most likely dissociation path-OD+: a1Δ or b1Σ+ → A 3Π → X 3Σ- → B 3Σ--involving a combination of spin-orbit and non-adiabatic charge transfer transitions is determined. The multi-step transition probability of this complex transition sequence in the intermediate fragment ion is directly evaluated as a function of the energy of the transient OD+ above its lowest dissociation limit from the measured ratio of the D+ + O+ + D and competing D+ + D+ + O sequential fragmentation channels, which are measured simultaneously. Our coupled-channel time-dependent dynamics calculations reproduce the general trends of these multi-state relative transition rates toward the three-body fragmentation channels.

Atomic autoionization in the photo-dissociation of super-excited deuterated water molecules fragmenting into D+ + O+ + D

We present the relaxation dynamics of deuterated water molecules via autoionization, initiated by the absorption of a 61 eV photon, producing the very rare D+ + O+ + D breakup channel. We employ the COLd target recoil ion momentum spectroscopy method to measure the 3D momenta of the ionic fragments and emitted electrons from the dissociating molecule in coincidence. We interpret the results using the potential energy surfaces extracted from multi-reference configuration interaction calculations. The measured particle energy distributions can be related to a super-excited monocationic state located above the double ionization threshold of D2O. The autoionized electron energy shows a sharp distribution centered around 0.5 eV, which is a signature of the atomic oxygen autoionization occurring in the direct and sequential dissociation processes of D2O+* at a large internuclear distance. In this way, an O+ radical fragment and a low-energy electron are created, both of which can trigger secondary reactions in their environment.

High-energy molecular-frame photoelectron angular distributions: a molecular bond-length ruler

We present a study on molecular-frame photoelectron angular distributions (MFPADs) of small molecules using circularly polarized synchrotron light. We find that the main forward-scattering peaks of the MFPADs are slightly tilted with respect to the molecular axis. This tilt angle is directly connected to the molecular bond length by a simple, universal formula. We apply the derived formula to several examples of MFPADs of C 1s and O 1s photoelectrons of CO, which have been measured experimentally or obtained by means of ab initio modeling. In addition, we discuss the influence of the back-scattering contribution that is superimposed over the analyzed forward-scattering peak in the case of homo-nuclear diatomic molecules such as N₂.

Antibiotics and antibiotic resistant bacteria/genes in urban wastewater: A comparison of their fate in conventional treatment systems and constructed wetlands

There is a growing concern that the use and misuse of antibiotics can increase the detection of antibiotic resistant genes (ARGs) in wastewater. Conventional wastewater treatment plants provide a pathway for ARGs and antibiotic resistant bacteria (ARB) to be released into natural water bodies. Research has indicated that conventional primary and secondary treatment systems can reduce ARGs/ARB to varying degrees. However, in developing/low-income countries, only 8-28% of wastewater is treated via conventional treatment processes, resulting in the environment being exposed to high levels of ARGs, ARB and pharmaceuticals in raw sewage. The use of constructed wetlands (CWs) has the potential to provide a low-cost solution for wastewater treatment, with respect to removal of nutrients, pathogens, ARB/ARGs either as a standalone treatment process or when integrated with conventional treatment systems. Recently, CWs have also been employed for the reduction of antibiotic residues, pharmaceuticals, and emerging contaminants. Given the benefits of ARG removal, low cost of construction, maintenance, energy requirement, and performance efficiencies, CWs offer a promising solution for developing/low-income countries. This review promotes a better understanding of the performance efficiency of treatment technologies (both conventional systems and CWs) for the reduction of antibiotics and ARGs/ARB from wastewater and explores workable alternatives.

Exploring the use of water resource recovery facility instrument data to visualise dynamic resilience to environmental stressors

Water resource recovery facilities (WRRF) face increasingly dynamic stressors, such as higher rainfall intensity and extended dry periods, which can exert stress on ageing water infrastructure and processes. These events can generate process stresses, which lead to wastewater process failures which result in pollution events that could be identified from instrument data used for operational/compliance monitoring. This extraction can be performed on two levels (1) for discrete processes that generate data to monitor process control variables and (2) at the WRRF process boundary (global), which is mainly used for compliance. Both levels of data hold valuable information on the dynamic influence of environmental stressors (cause) and the resulting process stress or resilience (effect) as 'dynamic resilience'. This paper proposes a novel methodology that uses actual water company instrument data to evaluate the 'discrete' (unit processes) and 'global' (WRRF boundary) dynamic resilience of a WRRF in the south of the UK. Dynamic resilience is presented as a four-stage methodology, which; (1) cleans WRRF data and extracts a standard operating condition; (2) identifies dynamic high and low flow environmental stressor events (one in five years); (3) models the process stresses and resilience generated by the imposed dynamic stressor before; (4) generating a contoured heat map of process-related stresses or resilience as a self ordering window. These methods demonstrate the possibility of visualising the dynamics of WRRF resilience (dynamic stressors and process stresses/resilience) resulting from high and low flow dynamic environmental stressors. Despite some challenges experienced with self ordering window scaling, the results demonstrate the possibility of identifying zones of process stress and resilience. It may also be possible to expand the methods developed to incorporate storm flows and combined sewer discharges.

Ultrafast temporal evolution of interatomic Coulombic decay in NeKr dimers

We investigate interatomic Coulombic decay in NeKr dimers after neon inner-valence photoionization [Ne⁺(2s^-1)] using a synchrotron light source. We measure with high energy resolution the two singly charged ions of the Coulomb-exploding dimer dication and the photoelectron in coincidence. By carefully tracing the post-collision interaction between the photoelectron and the emitted ICD electron we are able to probe the temporal evolution of the state as it decays. Although the ionizing light pulses are 80 picoseconds long, we determine the lifetime of the intermediate dimer cation state and visualize the contraction of the nuclear structure on the femtosecond time scale.

A conceptual framework for a multi-criteria decision support tool to select technologies for resource recovery from urban wastewater

In the context of circular economy, wastewater can be used to address some of the 21st century's challenges regarding the transition to renewable resources for water, energy, and nutrients. Despite all the research, development, and experience with resource recovery from urban wastewater, its implementation is still limited. The transition from treatment to resource recovery is complex due to the difficulty of selecting unit processes from a large number of candidate processes considering the operational limitations of each process, and sustainability objectives. Presently, a multi-criteria decision support tool that deals with the difficulty of unit process selection for resource recovery from wastewater has not been developed. Therefore, this paper presents the conceptual framework of a decision support tool to find the optimum treatment train consisting of compatible unit processes which can recover water, energy and/or nutrients from a specified influent composition. The framework presents the relationship between the user input, the knowledge library of technologies and a weighted multi-objective nonlinear programming model to aid process selection. The model presented here shows, not only how the processes are selected, but also the four-dimensional sustainability impact of the generated treatment train while considering the weight provided by the user. Thus, this study presents a reproducible framework which can support private and public decision-makers in transparent evidence-based decision making and eventually the systematic implementation of resource recovery from urban wastewater.

Fourfold Differential Photoelectron Circular Dichroism

We report on a joint experimental and theoretical study of photoelectron circular dichroism (PECD) in methyloxirane. By detecting O 1s photoelectrons in coincidence with fragment ions, we deduce the molecule's orientation and photoelectron emission direction in the laboratory frame. Thereby, we retrieve a fourfold differential PECD clearly beyond 50%. This strong chiral asymmetry is reproduced by ab initio electronic structure calculations. Providing such a pronounced contrast makes PECD of fixed-in-space chiral molecules an even more sensitive tool for chiral recognition in the gas phase.

Interleukin-1 receptor antagonist: An exploratory plasma biomarker that correlates with disability and provides pathophysiological insights in relapsing-remitting multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disorder. Interleukin-1 receptor antagonist (IL-1RA) is an endogenous soluble antagonist of the IL-1 receptor and blocks the pro-inflammatory effects of IL-1β known to contribute to MS pathology. The objectives of this study were to determine whether IL-1RA is associated with disability in MS and how this correlates with neurofilament light (NfL) levels in cerebrospinal fluid (CSF).

METHODS

Peripheral blood and CSF were collected from consenting MS patients. Patient demographic and clinical variables, including past relapse activity, were also collected. Circulating levels of IL-1RA, IL-18, and IL-1β were measured in plasma; IL-1RA and NfL were measured in the CSF via Bio-plex multiplex immunoassay kits and ELISA, respectively. IL-1RA expression was investigated in vitro using primary human macrophages and microglia, and in situ using post-mortem MS tissue.

RESULTS

Following a multiple regression analysis, IL-1RA levels in plasma correlated with expanded disability status scale score independent of all other variables. In a separate cohort, CSF IL-1RA significantly correlated with NfL. In vitro, induction of the NLRP3 inflammasome, a pathological hallmark within MS lesions, led to increased release of IL-1RA from primary human microglia and macrophages. In the CNS, IL-1RA⁺ macrophages/microglia were present at the rim of mixed active/inactive MS lesions.

CONCLUSIONS

Results presented in this study demonstrate that IL-1RA is a novel exploratory biomarker in relapsing-remitting MS, which correlates with disability and provides mechanistic insights into the regulatory inflammatory responses within the demyelinated CNS.

Male sex chromosomal complement exacerbates the pathogenicity of Th17 cells in a chronic model of central nervous system autoimmunity

Sex differences in multiple sclerosis (MS) incidence and severity have long been recognized. However, the underlying cellular and molecular mechanisms for why male sex is associated with more aggressive disease remain poorly defined. Using a T cell adoptive transfer model of chronic experimental autoimmune encephalomyelitis (EAE), we find that male Th17 cells induce disease of increased severity relative to female Th17 cells, irrespective of whether transferred to male or female recipients. Throughout the disease course, a greater frequency of male Th17 cells produce IFNγ, a hallmark of pathogenic Th17 responses. Intriguingly, XY chromosomal complement increases the pathogenicity of male Th17 cells. An X-linked immune regulator, Jarid1c, is downregulated in pathogenic male murine Th17 cells, and functional experiments reveal that it represses the severity of Th17-mediated EAE. Furthermore, Jarid1c expression is downregulated in CD4⁺ T cells from MS-affected individuals. Our data indicate that male sex chromosomal complement critically regulates Th17 cell pathogenicity.

Impact of hydraulic retention time on phosphorus removal from wastewater using reactive media

Phosphorus (P) discharge from wastewater treatment plants into the environment contributes to eutrophication issues. Reactive media filters represent an effective, simple and cost-effective solution to decrease the P content. Previous research used various experimental designs and often synthetic wastewater, making assessment of real-world performance difficult. This study assesses the impact of the hydraulic retention time (HRT) on P removal using real wastewater to refine design criteria for full-scale installations. Four media were compared in column experiments for >200 days. Different HRTs were applied and initially the media achieved low P effluent concentrations of >0.1 mg/L PO₄-P, increasing over time. Best P removal was observed for the highest HRT with on average >99%. HRT was seen to be the driving factor for P removal rather than media capacity. Three of the four materials showed pH levels above 12 initially, decreasing over time. Water quality parameters, including organics, solids and metals, were monitored. In-depth analysis confirmed formation of calcium phosphate precipitation on the media's surface. The results suggest the importance of an optimal HRT to achieve high P removal and show that the reactive media application is an appropriate technology for P removal on small sites if the elevated pH is addressed.

Vigorous cool room treadmill training to improve walking ability in people with multiple sclerosis who use ambulatory assistive devices: a feasibility study

Background

Aerobic training has the potential to restore function, stimulate brain repair, and reduce inflammation in people with Multiple Sclerosis (MS). However, disability, fatigue, and heat sensitivity are major barriers to exercise for people with MS. We aimed to determine the feasibility of conducting vigorous harness-supported treadmill training in a room cooled to 16 °C (10 weeks; 3times/week) and examine the longer-term effects on markers of function, brain repair, and inflammation among those using ambulatory aids.

Methods

Ten participants (9 females) aged 29 to 74 years with an Expanded Disability Status Scale ranging from 6 to 7 underwent training (40 to 65% heart rate reserve) starting at 80% self-selected walking speed. Feasibility of conducting vigorous training was assessed using a checklist, which included attendance rates, number of missed appointments, reasons for not attending, adverse events, safety hazards during training, reasons for dropout, tolerance to training load, subjective reporting of symptom worsening during and after exercise, and physiological responses to exercise. Functional outcomes were assessed before, after, and 3 months after training. Walking ability was measured using Timed 25 Foot Walk test and on an instrumented walkway at both fast and self-selected speeds. Fatigue was measured using fatigue/energy/vitality sub-scale of 36-Item Short-Form (SF-36) Health Survey, Fatigue Severity Scale, modified Fatigue Impact Scale. Aerobic fitness (maximal oxygen consumption) was measured using maximal graded exercise test (GXT). Quality-of-life was measured using SF-36 Health Survey. Serum levels of neurotrophin (brain-derived neurotrophic factor) and cytokine (interleukin-6) were assessed before and after GXT.

Results

Eight of the ten participants completed training (attendance rates ≥ 80%). No adverse events were observed. Fast walking speed (cm/s), gait quality (double-support (%)) while walking at self-selected speed, fatigue (modified Fatigue Impact Scale), fitness (maximal workload achieved during GXT), and quality-of-life (physical functioning sub-scale of SF-36) improved significantly after training, and improvements were sustained after 3-months. Improvements in fitness (maximal respiratory exchange ratio and maximal oxygen consumption during GXT) were associated with increased brain-derived neurotrophic factor and decreased interleukin-6.

Conclusion

Vigorous cool room training is feasible and can potentially improve walking, fatigue, fitness, and quality-of-life among people with moderate to severe MS-related disability.

Trial registration

The study was approved by the Newfoundland and Labrador Health Research Ethics Board (reference number: 2018.088) on 11/07/2018 prior to the enrollment of first participant (retrospectively registered at ClinicalTrials.gov: NCT04066972. Registered on 26 August 2019.

Presence of bacteria and bacteriophages in full-scale trickling filters and an aerated constructed wetland

Aerated Constructed Wetlands are a state-of-the-art design that provides a different physical and chemical environment (compared to traditional passive wetland designs) for the wastewater treatment processes and, thus, may have different pathogen removal characteristics. In order to establish the fate of bacterial and viral indicators, a field study was carried out at a Sewage Treatment Works (STW) in the UK (serving 20,000 pe). The STW consists of primary and secondary sedimentation tanks and trickling filters (TF) as the biological stage. A large (1,160 m²) pilot aerated Vertical Flow Constructed Wetland (AVFCW) was constructed at the STW as tertiary stage receiving ¼ of the total flow rate, i.e., 1250 m³/day. Effluent quality of the AVFCW complied with national and international standards for environmental discharge and reuse. For the first time, two sets of bacterial (Faecal coliforms, E.coli and intestinal enterococci) and viral indicators (Somatic coliphages, F-RNA specific bacteriophages and human-specific B. fragilis GB124 phages) were simultaneously investigated in an AVFCW and TF. High elimination rates were detected (up to 3.7 and 2.2 log reduction for bacteria indicators and phages, respectively) and strong correlations between the two sets were found. The superior efficiency of the aerated Constructed Wetlands in microbiological contamination removal compared to passive wetland systems was established for the first time, which may have implications for process selection for wastewater reuse. This field study therefore provides new evidence on the fate of bacteriophages and a first indication of their potential use for performance evaluation in TF and aerated Constructed Wetlands. It also demonstrates that the combination of TF with aerated constructed wetlands could be a novel and effective treatment scheme for new STW or for the upgrade of existing STW.

miR-223 promotes regenerative myeloid cell phenotype and function in the demyelinated central nervous system

In the injured central nervous system, myeloid cells, including macrophages and microglia, are key contributors to both myelin injury and repair. This immense plasticity emphasizes the need to further understand the precise molecular mechanisms that contribute to the dynamic regulation of myeloid cell polarization and function. Herein, we demonstrate that miR-223 is upregulated in multiple sclerosis (MS) patient monocytes and the alternatively-activated and tissue-regenerating M2-polarized human macrophages and microglia. Using miR-223 knock-out mice, we observed that miR-223 is dispensable for maximal pro-inflammatory responses, but is required for efficient M2-associated phenotype and function, including phagocytosis. Using the lysolecithin animal model, we further demonstrate that miR-223 is required to efficiently clear myelin debris and promote remyelination. These results suggest miR-223 constrains neuroinflammation while also promoting repair, a finding of important pathophysiological relevance to MS as well as other neurodegenerative diseases.

Separating Dipole and Quadrupole Contributions to Single-Photon Double Ionization

We report on a kinematically complete measurement of double ionization of helium by a single 1100 eV circularly polarized photon. By exploiting dipole selection rules in the two-electron continuum state, we observed the angular emission pattern of electrons originating from a pure quadrupole transition. Our fully differential experimental data and companion ab initio nonperturbative theory show the separation of dipole and quadrupole contributions to photo-double-ionization and provide new insight into the nature of the quasifree mechanism.

Lessons learned from volar plate fixation of scaphoid fracture nonunions

Treating scaphoid nonunions presents difficulties particularly when there is bone loss, significant humpback deformity or avascular necrosis. We describe a new type of fixation with a volar scaphoid plate that adds to the methods of internal fixation that are available for the treatment of recalcitrant scaphoid nonunions. We will also discuss 'lessons learned' from a cases series. The case series includes 20 consecutive patients treated with volar buttress plating and a pedicled vascularized bone graft from the ipsilateral volar distal radius. There was clinical and radiographic evidence of union in 18 of 20 patients, 13 of which were verified by computed tomographic scan. The range of motion was improved in all patients post-operatively. Four patients with radiographic union experienced intermittent clicking with maximal wrist flexion, believed to be due to the impingement of the plate on the volar aspect of the radioscaphoid articulation and underwent removal at approximately 1 year after the index procedure. Volar scaphoid plating is a useful alternative to headless scaphoid screw fixation in the treatment of unstable scaphoid waist fractures and nonunions.

LEVEL OF EVIDENCE

IV.

Imaging the square of the correlated two-electron wave function of a hydrogen molecule

The toolbox for imaging molecules is well-equipped today. Some techniques visualize the geometrical structure, others the electron density or electron orbitals. Molecules are many-body systems for which the correlation between the constituents is decisive and the spatial and the momentum distribution of one electron depends on those of the other electrons and the nuclei. Such correlations have escaped direct observation by imaging techniques so far. Here, we implement an imaging scheme which visualizes correlations between electrons by coincident detection of the reaction fragments after high energy photofragmentation. With this technique, we examine the H₂ two-electron wave function in which electron–electron correlation beyond the mean-field level is prominent. We visualize the dependence of the wave function on the internuclear distance. High energy photoelectrons are shown to be a powerful tool for molecular imaging. Our study paves the way for future time resolved correlation imaging at FELs and laser based X-ray sources.

Electron-electron correlation is a complex and interesting phenomenon that occurs in multi-electron systems. Here, the authors demonstrate the imaging of the correlated two-electron wave function in hydrogen molecule using the coincident detection of the electron and proton after the photoionization.

Pro-inflammatory activation of primary microglia and macrophages increases 18 kDa translocator protein expression in rodents but not humans

The 18kDa Translocator Protein (TSPO) is the most commonly used tissue-specific marker of inflammation in positron emission tomography (PET) studies. It is expressed in myeloid cells such as microglia and macrophages, and in rodent myeloid cells expression increases with cellular activation. We assessed the effect of myeloid cell activation on TSPO gene expression in both primary human and rodent microglia and macrophages in vitro, and also measured TSPO radioligand binding with ³H-PBR28 in primary human macrophages. As observed previously, we found that TSPO expression increases (∼9-fold) in rodent-derived macrophages and microglia upon pro-inflammatory stimulation. However, TSPO expression does not increase with classical pro-inflammatory activation in primary human microglia (fold change 0.85 [95% CI 0.58-1.12], p = 0.47). In contrast, pro-inflammatory activation of human monocyte-derived macrophages is associated with a reduction of both TSPO gene expression (fold change 0.60 [95% CI 0.45-0.74], p = 0.02) and TSPO binding site abundance (fold change 0.61 [95% CI 0.49-0.73], p < 0.0001). These findings have important implications for understanding the biology of TSPO in activated macrophages and microglia in humans. They are also clinically relevant for the interpretation of PET studies using TSPO targeting radioligands, as they suggest changes in TSPO expression may reflect microglial and macrophage density rather than activation phenotype.

Effects of fumarates on inflammatory human astrocyte responses and oligodendrocyte differentiation

Objective

Dimethyl fumarate (DMF) is a fumaric acid ester approved for the treatment of relapsing‐remitting multiple sclerosis (RRMS). In both the brain and periphery, DMF and its metabolite monomethyl fumarate (MMF) exert anti‐inflammatory and antioxidant effects. Our aim was to compare the effects of DMF and MMF on inflammatory and antioxidant pathways within astrocytes, a critical supporting glial cell in the central nervous system (CNS). Direct effects of fumarates on neural progenitor cell (NPC) differentiation toward the oligodendrocyte lineage were also assessed.

Methods

Primary astrocyte cultures were derived from both murine and human brains. Following pretreatment with MMF, DMF, or vehicle, astrocytes were stimulated with IL‐1β for 24 h; gene and microRNA expression were measured by qPCR. Cytokine production and reactive oxygen species (ROS) generation were also measured. NPCs were differentiated into the oligodendrocyte lineage in the presence of fumarates and immunostained using early oligodendrocyte markers.

Results

In both murine and human astrocytes, DMF, but not MMF, significantly reduced secretion of IL‐6, CXCL10, and CCL2; neither fumarate promoted a robust increase in antioxidant gene expression, although both MMF and DMF prevented intracellular ROS production. Pretreatment with fumarates reduced microRNAs ‐146a and ‐155 upon stimulation. In NPC cultures, DMF increased the number of O4⁺ and NG2⁺ cells.

Interpretation

These results suggest that DMF, and to a lesser extent MMF, mediates the anti‐inflammatory effects within astrocytes. This is supported by recent observations that in the inflamed CNS, DMF may be the active compound mediating the anti‐inflammatory effects independent from altered antioxidant gene expression.

Erratum: Electron Localization in Dissociating H_{2}^{+} by Retroaction of a Photoelectron onto Its Source [Phys. Rev. Lett. 116, 043001 (2016)]

This corrects the article DOI: 10.1103/PhysRevLett.116.043001.

Two-Particle Interference of Electron Pairs on a Molecular Level

We investigate the photodouble ionization of H_{2} molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasiparticle consisting of both electrons (i.e., the "dielectron") does. The work highlights the fact that nonlocal effects are embedded everywhere in nature where many-particle processes are involved.

Gender Differences in HIV-Related Neurological Progression in a Cohort of Injecting Drug Users Followed for 3.5 Years

We evaluated potential gender differences in the development of HIV related neurologic impairment, by matching 38 pairs of HIV positive male and female injecting drug users on their baseline age, education, disease stage and CD4 counts, and following them for 3.5 years. Adjusting for age, education, drug use, history of head injury and baseline CD4 count, more women had sensory abnormalities and symptoms than men at baseline, but the odds of having neurological impairment, particularly extrapyramidal signs and sensory abnormalities were increased over time in men but not in women. Men with ARC or AIDS had more neurological impairment than women in similar stages of illness. This study suggests further investigations of gender differences in HIV disease progression.

Agreement of Experiment and Theory on the Single Ionization of Helium by Fast Proton Impact

Even though the study of ion-atom collisions is a mature field of atomic physics, large discrepancies between experiment and theoretical calculations are still common. Here we present experimental results with high momentum resolution on the single ionization of helium induced by 1-MeV protons, and we compare these to theoretical calculations. The overall agreement is strikingly good, and even the first Born approximation yields good agreement between theory and experiment. This has been expected for several decades, but so far has not been accomplished. The influence of projectile coherence effects on the measured data is briefly discussed in terms of an ongoing dispute on the existence of nodal structures in the electron angular emission distributions.

Electron Localization in Dissociating H_{2}^{+} by Retroaction of a Photoelectron onto Its Source

We investigate the dissociation of H_{2}^{+} into a proton and a H^{0} after single ionization with photons of an energy close to the threshold. We find that the p^{+} and the H^{0} do not emerge symmetrically in the case of the H_{2}^{+} dissociating along the 1sσ_{g} ground state. Instead, a preference for the ejection of the p^{+} in the direction of the escaping photoelectron can be observed. This symmetry breaking is strongest for very small electron energies. Our experiment is consistent with a recent prediction by Serov and Kheifets [Phys. Rev. A 89, 031402 (2014)]. In their model, which treats the photoelectron classically, the symmetry breaking is induced by the retroaction of the long-range Coulomb potential onto the dissociating H_{2}^{+}.

Evaluation of a sequencing batch reactor sewage treatment rig for investigating the fate of radioactively labelled pharmaceuticals: Case study of propranolol

Pharmaceuticals are frequently detected in the aquatic environment, and have potentially damaging effects. Effluents from sewage treatment plants (STPs) are major sources of these substances. The use of sequencing batch reactor (SBR) STPs, involving cycling between aerobic and anoxic conditions to promote nitrification and denitrification, is increasing but these have yet to be understood in terms of removal of pharmaceutical residues. This study reports on the development of a laboratory rig to simulate a SBR. The rig was used to investigate the fate of radiolabelled propranolol. This is a commonly prescribed beta blocker, but with unresolved fate in STPs. The SBR rig (4.5 L) was operated on an 8 h batch cycle with settled sewage. Effective treatment was demonstrated, with clearly distinct treatment phases and evidence of nitrogen removal. Radiolabelled (14)C-propranolol was dosed into both single (closed) and continuous (flow-through) simulations over 13 SBR cycles. Radioactivity in CO2 off-gas, biomass and liquid was monitored, along with the characteristics of the sewage. This allowed apparent rate constants and coefficients for biodegradation and solid:water partitioning to be determined. Extrapolation from off-gas radioactivity measurements in the single dose 4-d study suggested that propranolol fell outside the definitions of being readily biodegradable (DegT50 = 9.1 d; 60% biodegradation at 12.0 d). During continuous dosing, 63-72% of propranolol was removed in the rig, but less than 4% of dose recovered as (14)CO2, suggesting that biodegradation was a minor process (Kbiol(M) L kg d(-1) = 22-49) and that adsorption onto solids dominated, giving rise to accumulations within biomass during the 17 d solid retention time in the SBR. Estimations of adsorption isotherm coefficients were different depending on which of three generally accepted denominators representing sorption sites was used (mixed liquor suspended solids, reactor COD or mass of waste activated sludge). With further development and evaluation, the rig developed for simulating SBR processes has potential to be used for informing better environmental risk assessments for those pharmaceuticals showing ambiguous results in field fate studies.

Developing food-grade coatings for dry-cured hams to protect against ham mite infestation

Dry-cured hams may become infested with ham mites, Tyrophagus putrescentiae, during the aging process. Methyl bromide is the only known available fumigant pesticide that is effective at controlling ham mite infestations in dry cured ham plants. However, methyl bromide will be phased out of all industries as early as 2015 due to its status as an ozone-depleting substance. Research was conducted to develop and evaluate the potential of using food-grade film coatings to control mite infestations, without affecting the aging process and sensory properties of the dry-cured hams. Cubes coated with xanthan gum+20% propylene glycol and carrageenan/propylene glycol alginate+10% propylene glycol were effective at controlling mite infestations under laboratory conditions. Water vapor permeability was measured to estimate the impact of coatings during the aging process. It was evident that carrageenan/propylene glycol alginate coatings were permeable to moisture, which potentially makes them usable during aging.

Sensory quality of broiler breast meat influenced by low atmospheric pressure stunning, deboning time and cooking methods

Stunning method (low atmospheric pressure stunning, LAPS and electrical stunning, ES), deboning time (0.75 h and 4 h), and cooking method (baking, frying, and sous vide) were evaluated for their impact on the descriptive sensory characteristics and consumer acceptability of breast meat (n=576, 144 birds per stunning × deboning time combination). Sensory evaluation was conducted by trained descriptive (n=8) and consumer (n=185) panels. On average, no differences (P>0.05) existed in the sensory acceptability of fried and sous vide cooked broiler breast treatment combinations. However, for oven-baking, the LAPS treatment that was deboned at 4 h was more acceptable (P<0.05) than other treatments and the ES and LAPS 4 h samples had greater (P<0.05) acceptability for texture than their ES and LAPS 0.75 h counterparts. Since consumers were highly variable in their liking of chicken breast treatments, consumers were grouped into clusters for each cooking method based on liking and preference. Cluster analysis data revealed that the largest groups of consumers liked (score≥6.0) all chicken breast treatments, but a larger proportion of consumers liked the 4 h LAPS and ES treatments when compared to the 0.75 h LAPS and ES treatments for all cooking methods. In addition, the consumers who indicated that baked chicken breast was highly acceptable preferred (P<0.05) 4 h LAPS over the 4 h ES samples. Based on sensory results, chicken breast meat from all stunning and deboning method combinations was highly acceptable to the majority of consumers, but the LAPS 4 h treatment had enhanced sensory characteristics when baked.

Fate of hydrocarbon pollutants in source and non-source control sustainable drainage systems

Sustainable drainage (SuDs) is an established method for managing runoff from developments, and source control is part of accepted design philosophy. However, there are limited studies into the contribution source control makes to pollutant removal, especially for roads. This study examines organic pollutants, total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs), in paired source and non-source control full-scale SuDs systems. Sites were selected to cover local roads, trunk roads and housing developments, with a range of SuDs, including porous asphalt, swales, detention basins and ponds. Soil and water samples were taken bi-monthly over 12 months to assess pollutant loads. Results show first flush patterns in storm events for solids, but not for TPH. The patterns of removal for specific PAHs were also different, reflecting varying physico-chemical properties. The potential of trunk roads for pollution was illustrated by peak runoff for TPH of > 17,000 μg/l. Overall there was no significant difference between pollutant loads from source and non-source control systems, but the dynamic nature of runoff means that longer-term data are required. The outcomes of this project will increase understanding of organic pollutants behaviour in SuDs. This will provide design guidance about the most appropriate systems for treating these pollutants.

Vibrationally resolved decay width of interatomic Coulombic decay in HeNe

We investigate the ionization of HeNe from below the He 1s3p excitation to the He ionization threshold. We observe HeNe+ ions with an enhancement by more than a factor of 60 when the He side couples resonantly to the radiation field. These ions are an experimental proof of a two-center resonant photoionization mechanism predicted by Najjari et al. [Phys. Rev. Lett. 105, 153002 (2010)]. Furthermore, our data provide electronic and vibrational state resolved decay widths of interatomic Coulombic decay in HeNe dimers. We find that the interatomic Coulombic decay lifetime strongly increases with increasing vibrational state.

Evolution of interatomic Coulombic decay in the time domain

During the past 15 years a novel decay mechanism of excited atoms has been discovered and investigated. This so-called interatomic Coulombic decay (ICD) involves the chemical environment of the electronically excited atom: the excitation energy is transferred (in many cases over long distances) to a neighbor of the initially excited particle usually ionizing that neighbor. It turned out that ICD is a very common decay route in nature as it occurs across van der Waals and hydrogen bonds. The time evolution of ICD is predicted to be highly complex, as its efficiency strongly depends on the distance of the atoms involved and this distance typically changes during the decay. Here we present the first direct measurement of the temporal evolution of ICD using a novel experimental approach.

Momentum-imaging apparatus for the study of dissociative electron attachment dynamics

An ion-momentum spectrometer is used to study the dissociative dynamics of electron attachment to molecules. A skimmed, supersonic gas jet is crossed with a pulsed beam of low-energy electrons, and the resulting negative ions are extracted toward a time- and position-sensitive detector. Calculations of the momentum in three dimensions may be used to determine the angular dependence of dissociative attachment as well as the energetics of the reaction.

Fat, oil and grease deposits in sewers: characterisation of deposits and formation mechanisms

Fat, oil and grease deposits (FOG) in sewers are a major problem and can cause sewer overflows, resulting in environmental damage and health risks. Often simplistically portrayed as cooling of fats, recent research has suggested that saponification may be involved in FOG formation. However there are still questions about the mechanisms effecting transformations in sewers and the role and source of metal cations involved in saponification. This study characterises FOG deposits from pumping stations, sewers and sewage works from different water hardness zones across the UK. The sites all had previous problems with FOG and most catchments contained catering and food preparation establishments. The FOG deposits were highly variable with moisture content ranging from 15 to 95% and oil content from 0 to 548 mg/g. Generally the pumping stations had lower moisture content and higher fat content, followed by the sewers then the sewage works. The water in contact with the FOG had high levels of oil (mean of about 800 mg/L) and this may indicate poor kitchen FOG management practices. FOG fatty acid profiles showed a transformation from unsaturated to saturated forms compared to typical cooking oils. This seems to relate to ageing in the sewer network or the mechanism of formation, as samples from pumping stations had higher proportions of C18:1 compared to C16. This may be due to microbial transformations by bacteria such as Clostridium sp. in a similar process to adipocere formation. There was an association between water hardness and increased Ca levels in FOG along with harder deposits and higher melting points. A link between FOG properties and water hardness has not been previously reported for field samples. This may also be due to microbial processes, such as biocalcification. By developing the understanding of these mechanisms it may be possible to more effectively control FOG deposits, especially when combined with promotion of behavioural change.

Imaging polyatomic molecules in three dimensions using molecular frame photoelectron angular distributions

We demonstrate a method for determining the full three-dimensional molecular-frame photoelectron angular distribution in polyatomic molecules using methane as a prototype. Simultaneous double Auger decay and subsequent dissociation allow measurement of the initial momentum vectors of the ionic fragments and the photoelectron in coincidence, allowing full orientation by observing a three-ion decay pathway, (H+, H+, CH2(+)). We find the striking result that at low photoelectron energies the molecule is effectively imaged by the focusing of photoelectrons along bond directions.

Impact of prior irregular infliximab dosing on performance of long-term infliximab maintenance therapy in Crohn's disease

BACKGROUND

Infliximab is efficacious in the management of moderate to severe Crohn's disease (CD). There are limited data regarding performance of infliximab in patients who require reinitiation of maintenance dosing following previous irregular exposure.

METHODS

This was a retrospective, observational study of CD patients treated with maintenance infliximab beyond 3 years. Maintenance infliximab infusion regimens were categorized as scheduled maintenance (SM) (maintenance infusions q < or =8 weeks after loading) or prior irregular (PI) (no loading, gap in therapy >8 weeks prior to or during maintenance therapy). We examined differences in need for medical and surgical hospitalizations as well as associated healthcare costs between the 2 groups.

RESULTS

In all, 104 CD patients met criteria for 3-year maintenance infliximab treatment (SM n = 64; PI n = 40). The rates of CD-related surgeries (60.9% and 55.0%, P = not significant [N.S.]) and medical hospitalizations (35.9% and 37.5%, P = N.S.) prior to infliximab initiation was similar between the 2 groups. However, the rate of medical (26.5% versus 47.5%, P = 0.035) and surgical hospitalizations (21.8% versus 48.7%, P = 0.009) were significantly lower in the SM compared to the PI group. During the third year of treatment the excess costs per patient for the PI group compared to the SM group amounted to $11,464 in spite of both cohorts being on SM therapy.

CONCLUSIONS

Patients who begin and continue an uninterrupted maintenance dosing regimen had a lower incidence of hospitalization and surgery than those who received an irregular or interrupted regimen prior to beginning an SM regimen.

Localization of electrogenic Na/bicarbonate cotransporter NBCe1 variants in rat brain

The activity of HCO(3)(-) transporters contributes to the acid-base environment of the nervous system. In the present study, we used in situ hybridization, immunoblotting, immunohistochemistry, and immunogold electron microscopy to localize electrogenic Na/bicarbonate cotransporter NBCe1 splice variants (-A, -B, and -C) in rat brain. The in situ hybridization data are consistent with NBCe1-B and -C, but not -A, being the predominant NBCe1 variants in brain, particularly in the cerebellum, hippocampus, piriform cortex, and olfactory bulb. An antisense probe to the B and C variants strongly labeled granule neurons in the dentate gyrus of the hippocampus, and cells in the granule layer and Purkinje layer (e.g. Bergmann glia) of the cerebellum. Weaker labeling was observed in the pyramidal layer of the hippocampus and in astrocytes throughout the brain. Similar, but weaker labeling was obtained with an antisense probe to the A and B variants. In immunoblot studies, antibodies to the A and B variants (alphaA/B) and C variant (alphaC) labeled approximately 130-kDa proteins in various brain regions. From immunohistochemistry data, both alphaA/B and alphaC exhibited diffuse labeling throughout brain, but alphaA/B labeling was more intracellular and punctate. Based on co-localization studies with antibodies to neuronal or astrocytic markers, alphaA/B labeled neurons in the pyramidal layer and dentate gyrus of the hippocampus, as well as cortex. alphaC labeled glia surrounding neurons (and possibly neurons) in the neuropil of the Purkinje cell layer of the cerebellum, the pyramidal cell layer and dentate gyrus of the hippocampus, and the cortex. According to electron microscopy data from the cerebellum, alphaA/B primarily labeled neurons intracellularly and alphaC labeled astrocytes at the plasma membrane. In summary, the B and C variants are the predominant NBCe1 variants in rat brain and exhibit different localization profiles.

Ultrafast probing of core hole localization in N2

Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question with an experiment that uses Auger electron angular emission patterns from molecular nitrogen after inner-shell ionization as an ultrafast probe of hole localization. The experiment, along with the accompanying theory, shows that observation of symmetry breaking (localization) or preservation (delocalization) depends on how the quantum entangled Bell state created by Auger decay is detected by the measurement.

MRI detection of macrophages labeled using micrometer-sized iron oxide particles

PURPOSE

To evaluate cellular labeling of immune cells using micron-sized iron oxide particles (MPIOs) and evaluate the MR relaxivity and MRI detection of the labeled cells.

MATERIALS AND METHODS

Immune cells isolated from mice and rats were labeled with three different sizes of MPIO particles (0.35, 0.90, or 1.63 microm). These labeled cells were characterized using transmission electron microscopy (TEM), fluorescence microscopy, flow cytometry, MR relaxometry, and MRI.

RESULTS

Macrophage uptake of MPIOs was found to be highest for the 1.63-microm size particles. MR relaxivity measurements indicated greater spin-spin relaxation for MPIO-labeled cells relative to cells labeled with nanometer-sized ultra-small superparamagnetic iron oxide (USPIO) particles with similar iron content. TEM and fluorescence microscopy indicated cellular uptake of multiple MPIO particles per cell. Macrophages labeled with 1.63-microm MPIOs had an average cellular iron uptake of 39.1 pg/cell, corresponding to approximately 35 particles per cell.

CONCLUSION

Cells labeled with one or more MPIO particles could be readily detected ex vivo at 11.7 Tesla and after infusion of the MPIO-labeled macrophages into the kidney of a rat, hypointense regions of the outer cortex are observed, in vivo, by MRI at 4.7 Tesla.

Effects of immunisation against leptin on feed intake, weight gain, fat deposition and laying performance in chickens

1. Three experiments were conducted to study the effects of leptin on weight gain and body composition in laying hens. 2. The effects of immunisation against chicken leptin on feed intake (FI), fat deposition and laying rate were observed in laying Guangdong yellow-feathered hens. Ten hens were inoculated with leptin immunogen on d 3, 31, 63 and 84, together with 10 control hens immunised with bovine serum albumin (BSA). In the 100-d experiment, immunisation against leptin increased blood anti-leptin antibody titres, slightly reduced plasma T3 concentrations, slightly decreased FI and increased live weight; however, laying rate was significantly depressed and abdominal fat mass was increased by the end of the 100-d experiment. 3. Passive immunisation of 50-d-old pullets with yolk extract containing anti-leptin antibody IgY significantly increased FI within 6 h of treatment compared with physiological saline treated controls. 4. In growing 70-d-old pullets, inoculation with 0.5 (group 1) or 1 (group 2) ml leptin immunogen on d 1 and 28 of the experiment slightly increased FI and significantly increased daily gain compared with BSA-immunised control pullets. Abdominal fat mass on d 49 increased from 48+/-4.5 g in controls to 66+/-3.5 and 80+/-3.1 g in groups 1 and 2, respectively. 5. It was suggested that immunisation against leptin mimicked loss of leptin bioactivity and might become a novel technique to stimulate fat growth in certain types of animal production.

Downhill treadmill running trains the rat spinotrapezius muscle

There are currently no models of exercise that recruit and train muscles, such as the rat spinotrapezius, that are suitable for transmission intravital microscopic investigation of the microcirculation. Recent experimental evidence supports the concept that running downhill on a motorized treadmill recruits the spinotrapezius muscle of the rat. Based on these results, we tested the hypothesis that 6 wk of downhill running (-14 degrees grade) for 1 h/day, 5 days/wk, at a speed of up to 35 m/min, would 1) increase whole body peak oxygen uptake (Vo(2 peak)), 2) increase spinotrapezius citrate synthase activity, and 3) reduce the fatigability of the spinotrapezius during electrically induced 1-Hz submaximal tetanic contractions. Trained rats (n = 6) elicited a 24% higher Vo(2 peak) (in ml.min(-1).kg(-1): sedentary 58.5 +/- 2.0, trained 72.7 +/- 2.0; P < 0.001) and a 41% greater spinotrapezius citrate synthase activity (in mumol.min(-1).g(-1): sedentary 14.1 +/- 0.7, trained 19.9 +/- 0.9; P < 0.001) compared with sedentary controls (n = 6). In addition, at the end of 15 min of electrical stimulation, trained rats sustained a greater percentage of the initial tension than their sedentary counterparts (control 34.3 +/- 3.1%, trained 59.0 +/- 7.2%; P < 0.05). These results demonstrate that downhill running is successful in promoting training adaptations in the spinotrapezius muscle, including increased oxidative capacity and resistance to fatigue. Since the spinotrapezius muscle is commonly used in studies using intravital microscopy to examine microcirculatory function at rest and during contractions, our results suggest that downhill running is an effective training paradigm that can be used to investigate the mechanisms for improved microcirculatory function following exercise training in health and disease.

Biodegradation of [(14)C] ring-labeled nonylphenol ethoxylate

Nonylphenol (NP) and the 9-mole ethoxylate of nonylphenol (NPE9) were synthesized with a uniform radioactive (14)C label in the aromatic ring. The [(14)C]NP isomer distribution and [(14)C]NPE9 oligomer distribution closely matched that of commercial NPE9. Biodegradation of [(14)C]NPE9 was examined under conditions simulating a river water environment, and changes in the oligomer distribution and mineralization to (14)CO(2) were monitored for 128 days. Over 40% of the [(14)C]NPE aromatic ring carbon was converted to (14)CO(2) and another 21% was incorporated into the biomass. Primary degradation of NPE (conversion to metabolites other than NP, NPE ethoxylates, and NPE carboxylates) was estimated to be 87-97%. NP was a minor metabolite, accounting for less than 0.4% of the initial NPE. These studies demonstrate that the phenolic ring of NPE is opened, metabolized, and mineralized in the aquatic environment.

In situ labeling of immune cells with iron oxide particles: an approach to detect organ rejection by cellular MRI

In vivo cell tracking by MRI can provide means to observe biological processes and monitor cell therapy directly. Immune cells, e.g., macrophages, play crucial roles in many pathophysiological processes, including organ rejection, inflammation, autoimmune diseases, cancer, atherosclerotic plaque formation, numerous neurological disorders, etc. The current gold standard for diagnosing and staging rejection after organ transplantation is biopsy, which is not only invasive, but also prone to sampling errors. Here, we report a noninvasive approach using MRI to detect graft rejection after solid organ transplantation. In addition, we present the feasibility of imaging individual macrophages in vivo by MRI in a rodent heterotopic working-heart transplantation model using a more sensitive contrast agent, the micrometer-sized paramagnetic iron oxide particle, as a methodology to detect acute cardiac rejection.

Progressive changes in water and sediment quality in a wetland system for control of highway runoff

Innovative wetland based systems were designed and installed on the Newbury Bypass, Berkshire, England to provide flow balancing and pollution control for road runoff. The systems were monitored over 18 months to evaluate performance, pollutant removal processes and offer improved design and operation codes for this new application of wetlands. Water quality, sediment accumulation rates, and metal concentrations in size-fractionated, settling solids and deposited sediments were determined in parts of the system to provide information on spatial and temporal variability. The results presented here show that over the long term, there were progressive changes in parts of the system for BOD and COD and for metal concentrations in the sediment fractions, which occurred with linear (or semi log-linear) rates, despite variability in flow rates, retention times and in pollutant loading to the system. Future work will continue monitoring to increase the data set, examine possible processes contributing to the regression constants, and test the potential use of the regressions in system modelling. Attempts at modelling road runoff treatment using wetlands must allow for progressions, since the systems can only be effective if they retain removed metals in the sediment sink.

A phylogenetic analysis of basal metabolism, total evaporative water loss, and life-history among foxes from desert and mesic regions

We measured basal metabolic rate (BMR) and total evaporative water loss (TEWL) of species of foxes that exist on the Arabian Peninsula, Blanford's fox (Vulpes cana) and two subspecies of Red fox (Vulpes vulpes). Combining these data with that on other canids from the literature, we searched for specialization of physiological traits among desert foxes using both conventional least squares regression and regressions based on phylogenetic independent contrasts. Further, we explored the consequences of reduced body size of foxes on life history parameters such as litter size and neonate mass. For Blanford's foxes, Red foxes from the central desert of Arabia, and Red foxes from the more mesic Asir mountains, body mass averaged 1,285 +/- 52 g, 1,967 +/- 289 g, and 3,060 +/- 482 g, respectively, whereas mean BMR, during summer, was 304.5 +/- 32.3 kJ/day, 418.0 +/- 32.4 kJ/day, and 724.1 +/- 120.2 kJ/day (+/- SD). An analysis of covariance with body mass as a covariate showed no statistical differences in BMR among foxes. Analysis of covariance indicated that Red fox from the Asir mountains had a higher TEWL than Red foxes from central Arabia or than Blanford's foxes also from the mountains. Comparisons of all species of desert and mesic foxes showed no significant differences in BMR, nor did desert foxes have a significantly lower BMR than other carnivores. TEWL of desert foxes was lower than other more mesic carnivores; deviations in TEWL ranged from -17.7% for the Fennec fox (Fennecus zerda) to -57.4% for the Kit fox (Vulpes velox). Although desert foxes have a BMR comparable to other more mesic species, it appears that desert foxes do have a smaller body mass, lowering overall energy requirements. We attribute this reduction in body size to the "resource limitation hypothesis" whereby natural selection favors smaller individuals in a resource-limited environment, especially during periods of severe food shortage. However, until common garden experiments are performed, developmental plasticity and acclimation cannot be ruled out as contributors to this pattern.

Matrix-assisted laser desorption/ionization mass spectrometry of discrete mass poly(butylene glutarate) oligomers

The mass dependency of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) response has been studied using equimolar mixtures of synthetic discrete mass poly(butylene glutarate) (PBG) oligomers of known structure having degrees of polymerization of 8, 16, 32, and 64. Mass discrimination observed was attributed to choice of matrix and detector saturation caused by higher laser intensity and inclusion of matrix ions in the MALDI spectra. Optimization of sample preparation and instrumental parameters provided uniform response over the mass ranged spanned by these four oligomers. The oligomer mixture was shown to serve as a model of more complex polymer distributions in the mass range 780-6000 Da, and application of the discrete mass oligomers as internal and calibration standards was demonstrated. Inclusion of PBG discrete mass oligomers as an internal standard in a quasi-equimolar mixture with polydispersed poly(butylene adipate) (PBA) indicated that some diminution of response occurred during the analysis of this mixture of materials. Reasons for differences in the corrected molecular weight averages of the polydispersed PBA obtained from measurements using MALDI and GPC were studied using individual discrete mass oligomers as calibration standards for GPC. The data indicated that differences in hydrodynamic volumes of PBG oligomers and PEG standards at similar masses resulted in an overestimation by GPC of the molecular weight averages of the PBA distribution.

Hemodynamic response profile predicts susceptibility to cocaine-induced toxicity

Cocaine evokes pressor responses due either to a large increase in systemic vascular resistance despite a decrease (>8%) in cardiac output (vascular responders) or to small increases in both cardiac output and vascular resistance (mixed responders) in conscious rats. These studies were designed to determine (1) if the hemodynamic response pattern to cocaine correlates with relative sensitivity to toxicity and (2) if altering the hemodynamic response pattern to cocaine using propranolol enhances toxicity. Rats were instrumented for determination of cardiac output and arterial pressure. After recovery, rats were classified as vascular or mixed responders to cocaine (5 mg/kg, i.v., four to six trials). Two weeks later, cocaine was infused (1.5 mg/kg/min) until death after pretreatment with saline or propranolol (1 mg/kg). Saline-pretreated mixed responders (n=6) had greater tolerance to cocaine toxicity compared to vascular responders (n=11). Furthermore, saline-pretreated vascular responders were less sensitive than propranolol-pretreated vascular responders (n=9) to cocaine toxicity. Therefore, we propose that the initial hemodynamic response pattern to cocaine predicts sensitivity to cocaine toxicity. In addition, propranolol, a drug that enhances the increase in vascular resistance to cocaine, also increases toxicity to cocaine in vascular responders.

Behaviour of metals associated with sediments in a wetland based system for road runoff control

Innovative road runoff control systems, which combined flow-balancing basins with constructed wetlands, on the recently constructed Newbury Bypass were monitored over 18 months. The results have shown that despite variability in the pollutant loadings, the system generally promoted removal and accumulation of sediments and associated metals. The correlation structure of the data set indicated possible removal processes, and enabled interpretation of the behaviour of these pollutants. Correlation of metal content in settling solids between successive upstream and downstream parts of the wetland gave indications of potential regression models for metal behaviour, despite variability in flows, pollutant loadings, and other conditions. Other findings suggested that the combined flow balancing and pollutant removal functions could be improved by avoiding transport of sediments, fluctuations in conditions and by the promotion of processes favouring metal retention by bed deposits.