Pathogen and Particle Associations in Wastewater: Significance and Implications for Treatment and Disinfection Processes.

Disinfection guidelines exist for pathogen inactivation in potable water and recycled water, but wastewater with high numbers of particles can be more difficult to disinfect, making compliance with the guidelines problematic. Disinfection guidelines specify that drinking water with turbidity ≥1 Nephelometric Turbidity Units (NTU) is not suitable for disinfection and therefore not fit for purpose. Treated wastewater typically has higher concentrations of particles (1-10NTU for secondary treated effluent). Two processes widely used for disinfecting wastewater are chlorination and ultraviolet radiation. In both cases, particles in wastewater can interfere with disinfection and can significantly increase treatment costs by increasing operational expenditure (chemical demand, power consumption) or infrastructure costs by requiring additional treatment processes to achieve the required levels of pathogen inactivation. Many microorganisms (viruses, bacteria, protozoans) associate with particles, which can allow them to survive disinfection processes and cause a health hazard. Improved understanding of this association will enable development of cost-effective treatment, which will become increasingly important as indirect and direct potable reuse of wastewater becomes more widespread in both developed and developing countries. This review provides an overview of wastewater and associated treatment processes, the pathogens in wastewater, the nature of particles in wastewater and how they interact with pathogens, and how particles can impact disinfection processes.

Further characterization of a rat model of varicella zoster virus-associated pain: Relationship between mechanical hypersensitivity and anxiety-related behavior, and the influence of analgesic drugs.

Persistent herpes zoster-associated pain is a significant clinical problem and an area of largely unmet therapeutic need. Progress in elucidating the underlying pathophysiology of zoster-associated pain and related co-morbidity behavior, in addition to appropriately targeted drug development has been hindered by the lack of an appropriate animal model. This study further characterizes a recently developed rat model of zoster-associated hypersensitivity and investigates (a) response to different viral strains; (b) relationship between viral inoculum concentration ('dose') and mechanical hypersensitivity ('response'); (c) attenuation of virus-associated mechanical hypersensitivity by clinically useful analgesic drugs; and (d) measurement of pain co-morbidity (anxiety-like behavior) and pharmacological intervention in the open field paradigm (in parallel with models of traumatic peripheral nerve injury). Varicella zoster virus was propagated on fibroblast cells before s.c. injection into the glabrous footpad of the left hind limb of adult male Wistar rats. Control animals received injection of uninfected fibroblast cells. Hind-limb reflex withdrawal thresholds to mechanical, noxious thermal and cooling stimuli were recorded at specified intervals post-infection. Infection with all viral strains was associated with a dose-dependent mechanical hypersensitivity but not a thermal or cool hypersensitivity. Systemic treatment with i.p. morphine (2.5 mg/kg), amitriptyline (10 mg/kg), gabapentin (30 mg/kg), (S)-(+)-ibuprofen (20 mg/kg) and the cannabinoid WIN55,212-2 (2 mg/kg) but not the antiviral, acyclovir (50 mg/kg), was associated with a reversal of mechanical paw withdrawal thresholds. In the open field paradigm, virus-infected and nerve-injured animals demonstrated an anxiety-like pattern of ambulation (reduced entry into the central area of the open arena) which was positively correlated with mechanical hypersensitivity. This may reflect pain-related co-morbidity. Further, anxiety-like behavior was attenuated by acute i.p. administration of gabapentin (30 mg/kg) in nerve-injured, but not virus-infected animals. This model will prove useful in elucidating the pathophysiology of zoster-associated pain and provide a tool for pre-clinical screening of analgesic drugs.

The effect of the palmitoylethanolamide analogue, palmitoylallylamide (L-29) on pain behaviour in rodent models of neuropathy.

BACKGROUND AND PURPOSE: Cannabinoids are associated with analgesia in acute and chronic pain states. A spectrum of central cannabinoid (CB(1)) receptor-mediated motor and psychotropic side effects limit their therapeutic potential. Here, we investigate the analgesic effect of the palmitoylethanolamide (PEA) analogue, palmitoylallylamide (L-29), which via inhibition of fatty acid amide hydrolase (FAAH) may potentiate endocannabinoids thereby avoiding psychotropic side effects. EXPERIMENTAL APPROACH: The in vivo analysis of the effect of L-29 on measures of pain behaviour in three rat models of neuropathic pain. KEY RESULTS: Systemically administered L-29 (10 mg kg(-1)) reduced hypersensitivity to mechanical and thermal stimuli in the partial sciatic nerve injury (PSNI) model of neuropathic pain; and mechanical hypersensitivity in a model of antiretroviral (ddC)-associated hypersensitivity and a model of varicella zoster virus (VZV)-associated hypersensitivity. The effects of L-29 were comparable to those of gabapentin (50 mg kg(-1)). The CB(1) receptor antagonist SR141716a (1 mg kg(-1)) and the CB(2) receptor antagonist SR144528 (1 mg kg(-1)) reduced the effect of L-29 on hypersensitivity in the PSNI and ddC models, but not in the VZV model. The peroxisome proliferator-activated receptor-alpha antagonist, MK-886 (1 mg kg(-1)), partially attenuated the effect of L-29 on hypersensitivity in the PSNI model. L-29 (10 mg kg(-1)) significantly attenuated thigmotactic behaviour in the open field arena without effect on locomotor activity. CONCLUSIONS AND IMPLICATIONS: L-29 produces analgesia in a range of neuropathic pain models. This presents L-29 as a novel analgesic compound that may target the endogenous cannabinoid system while avoiding undesirable side effects associated with direct cannabinoid receptor activation.

Quantification of the rat spinal microglial response to peripheral nerve injury as revealed by immunohistochemical image analysis and flow cytometry.

Microgliosis is implicated in the pathophysiology of several neurological disorders, including neuropathic pain. Consequently, perturbation of microgliosis is a mechanistic and drug development target in neuropathic pain, which highlights the requirement for specific, sensitive and reproducible methods of microgliosis measurement. In this study, we used the spinal microgliosis associated with L5 spinal nerve transection and minocycline-induced attenuation thereof to: (1) evaluate novel software based semi-quantitative image analysis paradigms for the assessment of immunohistochemical images. Microgliosis was revealed by immunoreactivity to OX42. Several image analysis paradigms were assessed and compared to a previously validated subjective categorical rating scale. This comparison revealed that grey scale measurement of the proportion of a defined area of spinal cord occupied by OX42 immunoreactive cells is a robust image analysis paradigm. (2) Develop and validate a flow cytometric approach for quantification of spinal microgliosis. The flow cytometric technique reliably quantified microgliosis in spinal cord cell suspensions, using OX42 and ED9 immunoreactivity to identify microglia. The results suggest that image analysis of immunohistochemical revelation of microgliosis reliably detects the spinal microgliosis in response to peripheral nerve injury and pharmacological attenuation thereof. In addition, flow cytometry provides an alternative approach for quantitative analysis of spinal microgliosis elicited by nerve injury.

Evaluation of the Abraxis Strip Test for Microcystins™ for use with wastewater effluent and reservoir water.

Rapid tests for the microcystin-type cyanobacterial toxins that are designed to be able to be used in the field have recently become available. The tests provide a semi-quantitative result over a relatively narrow concentration range (10-fold) and are available with detection limits relevant for drinking water and recreational water compliance testing (1 µg/L and 10 µg/L, respectively). The aim of this research was to assess the applicability of these tests for the determination of microcystin-related toxicity in treated effluent from the Western Treatment Plant and potable source water from Tarago Reservoir, both near Melbourne, Australia. Accuracy, precision, cross-reactivity, matrix effects and inter-operator variability were assessed. The claimed mLR concentration response range of the tests was confirmed within reasonable limits, although the false negative and false positive rates were significant for spike concentrations below 2.5 µg/L (Recreational Strip Test). Inter-operator variability was reasonably high (CV=23%) and this was exacerbated by the use of untrained scorers. Contributing to this was significant inter-assay variability in test band intensity (CV=28%). The strip tests responded to all 8 microcystin analogues tested and also to a mixture of another 7 analogues contained in a Certified Bloom Material. Cross-reactivity was always greater than 50%. Matrix effects due to the test waters or to cyanobacterial cell material were also relatively minor, being of the order of 2-fold at the maximum. Overall, these Strip Tests were found to be reliable for relatively rapid detection of microcystins around the upper limits of their response ranges, as recommended by the manufacturer. While the Recreational Water Strip test was less reliable in the lower ranges, it can be used in conjunction with the Drinking Water Strip test to reduce uncertainty around the 1 µg/L concentration. Despite limitations, both strip tests provide near real-time information which can assist with day to day operational decisions. When results indicate microcystin concentrations near compliance limits it is recommended that use of the test kits should be supported by accurate quantitative toxin testing together with traditional algal cell counts, and possibly emerging qPCR methods for species and toxin gene detection.

The correlation between pain-related behaviour and spinal microgliosis in four distinct models of peripheral neuropathy.

BACKGROUND: Peripheral nerve injury is associated with a spinal microglial response that has been correlated with the development of behaviours reflective of neuropathic pain. METHODS: To examine whether this phenomenon is generalizable to neuropathic pain of non-traumatic aetiology, this study investigated the association between spinal microgliosis and behavioural measures of neuropathic hypersensitivity and pain-related anxiety behaviour in four distinct rat models of peripheral neuropathic pain. These were traumatic neuropathy [L5 spinal nerve transection (SNT)], HIV-related neuropathies (either treatment with the antiretroviral drug Zalcitabine (ddC) or combination of perineural exposure to the HIV-gp120 protein and ddC treatment) and varicella zoster virus (VZV) infection. RESULTS AND CONCLUSION: Persistent mechanical hypersensitivity developed in all 'neuropathic' rats. However, spinal microgliosis, as measured by increased CD11b/c immunohistochemical staining and increased numbers of cells expressing CD11b measured by flow cytometry, was evident in the SNT and to a lesser extent in the HIV neuropathy models but not the VZV model. These results suggest that behavioural hypersensitivity and thigmotaxis can only be linked to a microglial response in certain models of neuropathy.