Alteration of cholinesterase activity as possible mechanism of silver nanoparticle toxicity

Due to their broad-spectrum antimicrobial activity, silver nanoparticles (AgNPs) have been used in a large number of commercial and medical products. Such proliferated AgNP production poses toxicological and environmental issues which need to be addressed. The present study aimed to investigate the effects of AgNPs on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), important enzymes in areas of neurobiology, toxicology and pharmacology. Three different AgNPs, prepared by the chemical reduction using trisodium citrate, hydroxylamine hydrochloride (Cl-AgNPs), and borohydride following stabilization with poly(vinyl alcohol), were purified and characterised with respect to their sizes, shapes and optical properties. Their inhibition potential on AChE and BChE was evaluated in vitro using an enzyme assay with o-nitrophenyl acetate or o-nitrophenyl butyrate as substrates, respectively. All three studied AgNPs were reversible inhibitors of ChEs. Among tested nanoparticles, Cl-AgNP was found to be the most potent inhibitor of both AChE and BChE. Although the detailed mechanism by which the AgNPs inhibit esterase activities remains unknown, structural perturbation of the enzyme may be the common mode of ChE inhibition by AgNPs.     

The effect of bee pollen on secretion activity, markers of proliferation and apoptosis of porcine ovarian granulosa cells in vitro

The general objective of this in vitro study was to examine the effect of bee pollen on the release of insulin-like growth factor I (IGF-I) and steroid hormone progesterone, and expression of markers of proliferation (PCNA) and apoptosis (caspase-3) in porcine ovarian granulosa cells. Concentrations of IGF-I and progesterone were determined by RIA method and expression of PCNA and caspase-3 by immunocytochemistry. Bee pollen addition at the dose of 10 ng/mL significantly (P<0.05) inhibited IGF-I release by porcine ovarian granulosa cells. This growth factor was not influenced by 100 and 1000 ng/mL doses of bee pollen. Progesterone release by cells was not influenced by bee pollen addition at the doses of 10, 100 and 1000 ng/mL as used in our study. Similarly expression of PCNA and caspase-3 was not affected by bee pollen addition. The present study shows dose-dependent regulation of IGF-I by experimental bee pollen addition in vitro. Progesterone release, expression of PCNA and caspase-3 in porcine ovarian granulosa cells was not induced by pollen. Our results contribute to new insights regarding the possible effect of bee pollen on IGF-I release, which is important for regulation of porcine ovarian functions.     

Effects of azinphos-methyl exposure on enzymatic and non-enzymatic antioxidant defenses in Biomphalaria glabrata and Lumbriculus variegatus

Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The oligochaete Lumbriculus variegatus and pigmented and non-pigmented specimens of the gastropod Biomphalaria glabrata are freshwater invertebrates that have been recommended for contamination studies. Recently, it has been shown that L. variegatus worms exhibit a higher cholinesterase (ChE) activity and a greater sensitivity to in vivo ChE inhibition by azinphos-methyl than pigmented B. glabrata snails. The aims of the present study were (1) to investigate if, in addition to its anticholinesterase action, azinphos-methyl has also pro-oxidant activity in L. variegatus and B. glabrata, and (2) to examine if species that are highly susceptible to the neurotoxic effects of organophosphates also suffer a greater degree of oxidative stress. Therefore, total glutathione (t-GSH) levels and activities of cholinesterase (ChE), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glucose 6-phosphate dehydrogenase (G6PDH) were measured in the whole body soft tissue of organisms exposed for 48 and 96 h to a level of azinphos-methyl that produces 50% of inhibition on ChE. Results showed different patterns of antioxidant responses between the gastropods and the oligochaetes, and even between the two phenotypes of gastropods: (1) in exposed L. variegatus t-GSH levels increased and CAT and SOD activities decreased with respect to control organisms, (2) in pigmented gastropods, SOD decreased while CAT transiently diminished, and (3) in non-pigmented gastropods, SOD activity showed a biphasic response. GST and G6PDH were not altered by azinphos-methyl exposure. Of note, t-GSH levels were 4-fold times higher in L. variegatus than in both phenotypes of B. glabrata. This may suggest that GSH could play a more important role in antioxidant defense in L. variegatus than in B. glabrata.     

Virological Characterization of Roof-Harvested Rainwater of Densely Urbanized Low-Income Region

Food and Environmental Virology - Roof-harvested rainwater (RHRW) is considered relatively clean water, even though the possible presence of pathogens in the water may pose human health risks. In...     

Electrochemical detection and degradation of ibuprofen from water on multi-walled carbon nanotubes-epoxy composite electrode

This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes,i.e.,multi-walled carbon nanotubes-epoxy(MWCNT) and silver-modified zeolite-multi-walled carbon nanotubes-epoxy(AgZMWCNT) composites electrodes.The composite electrodes were obtained using two-roll mill procedure.SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix.AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area.The electrochemical determination of ibuprofen(IBP) was achieved using AgZMWCNT by cyclic voltammetry,differential-pulsed voltammetry,square-wave voltammetry and chronoamperometry.The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs.Ag/AgCl,and IBP concentration was determined comparatively by differential-pulsed voltammetry,under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode.AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.     

A study of osteological and molecular differences in populations of Aphanius fasciatus Nardo 1827, from the central Mediterranean (Teleostei, Cyprinodontidae)

Nine populations of Aphanius fasciatus Nardo, 1827 from the central Mediterranean were analysed by examining the mitochondrial control region and the morphology of the bony elements of the skull and vertebral column, to study the degree of intraspecific differentiation of A. fasciatus considering the level of isolation of the different populations and the palaeogeographic history of the central Mediterranean area. Both the molecular and morphological analyses differentiate between the populations, even if the topologies of the two trees are different. Molecular and osteological investigations have consistently demonstrated a well-supported differentiation of the south-eastern Sicilian populations both within the same group (Tigano et al. in Ital J Zool 71:1124–1133, 2004a; Tigano et al. in Abstract volume XI European Congress of Ichthyology, Tallin, Estonia, 2004b), and from the populations from western Sicily, Tunisia and the island of Malta. The molecular results show that the nine populations are characterised by haplotypes that are well defined in relation to a probably limited gene flow; while, as regards the morphological data the differentiation found could be explained in terms of the geographic isolation of the various populations, although the influence of environmental factors, which differ greatly between the various sites where the populations live, cannot be ruled out.     

Influence of atmospheric stability on the mass concentration and chemical composition of atmospheric particles: a case study in Rome, Italy

PM(10) concentration and chemical composition (ions and carbon compounds) at three sampling stations in Rome and in its surroundings was determined daily during a one-month field study, carried out during December 2003. PM concentration at the traffic station was considerably higher than at the urban background and semi-rural stations; elemental carbon was detected as one of the chemical components responsible for this increase. The difference in the concentration of sulphate and ammonium was negligible, as it was expected for secondary pollutants. A negative artefact in the determination of ammonium nitrate by means of heated automatic monitors was highlighted. The dilution properties of the lower atmosphere were traced by means of a natural radioactivity monitor. This parameter has been found to play an essential role in pollution buildup. A considerable increase in PM concentration was observed to coincide with periods of atmospheric stability. The main difference in PM composition between periods of high concentration and periods of "clean" air was found to be in the increase of ammonium nitrate concentration.     

Validation of Ucides cordatus as a bioindicator of oil contamination and bioavailability in mangroves by evaluating sediment and crab PAH records

This study is aimed at verifying the relevance of Ucides cordatus as a bioindicator of oil contamination and PAH bioavailability in mangrove sediments. For this, crabs and sediment cores were sampled from five mangroves, including an area suspected of contamination derived from an MF380 oil spillage, and analyzed for the 16 PAH in the USEPA priority list as well as for the five series of alkylated homologues. Concentrations in sediments varied from 35 microg kg-1 in the lower core layer of the control area to 33,000 microg kg-1 in the upper layer of the most contaminated area. Total PAH contents in crabs varied from 206 to 62,000 microg kg-1 and were closely correlated to that in sediments. In general, individual PAH profiles in both matrices were in good agreement. Phenanthrenes, however, were more predominant in crabs making up to 30-46% of the Total PAH. Accumulation factors found in the range of 0.7 to 35 were highly variable even after normalizing concentrations for organic carbon and lipid content. Survival in highly contaminated environment and reliable record of environmental contamination in the tissue provide evidence that U. cordatus is an excellent bioindicator for oil in mangroves.     

Contributions of green infrastructure to enhancing urban resilience

After briefly reviewing key resilience engineering perspectives and summarising some green infrastructure (GI) tools, we present the contributions that GI can make to enhancing urban resilience and maintaining critical system functionality across complex integrated social–ecological and technical systems. We then examine five key challenges for the effective implementation of GI that include (1) standards; (2) regulation; (3) socio-economic factors; (4) financeability; and (5) innovation. We highlight ways in which these challenges are being dealt with around the world, particularly through the use of approaches that are both context appropriate and socially inclusive. Although progress surmounting these challenges has been made, more needs to be done to ensure that GI approaches are inclusive and appropriate and feature equally alongside more traditional ‘grey’ infrastructure in the future of urban resilience planning. This research was undertaken for the Resilience Shift initiative to shift the approach to resilience in practice for critical infrastructure sectors. The programme aims to help practitioners involved in critical infrastructure to make decisions differently, contributing to a safer and better world.