Nanotossicologia dei quantum dot di CdS in linee cellulari umane

Le nanotecnologie sono un settore emergente in rapida crescita, come dimostra l'esplosione del mercato dei prodotti ad esso collegati. I quantum dot di cadmio solfuro (CdS QD) sono ampiamente utilizzati per la produzione di materiali semiconduttori e dispositivi optoelettronici; tuttavia, non sono ancora completamente chiari gli effetti di questi nanomateriali sulla salute umana. Questo lavoro di dottorato si pone l'obbiettivo di definire il potenziale citotossico e genotossico dei CdS QD in linee cellulari umane e definirne il meccanismo implicato. A questo scopo, essendo il fegato uno dei principali organi di accumulo del cadmio e dei nanomateriali a base di cadmio, è stata utilizzata la linea cellulare HepG2 derivante da un epatocarcinoma umano. È stato evidenziato, in seguito all'assorbimento, da parte delle cellule, dei CdS QD, un effetto citotossico, con conseguente modulazione dell'espressione genica di una serie di geni coinvolti sia nei processi di rescue (autofagia, risposta allo stress) sia in quelli di morte cellulare programmata. È stato, inoltre, dimostrata l'assenza di un rilevante effetto genotossico dipendente da questi nanomateriali. Infine, è stato osservato che cellule esposte ai CdS QD presentano mitocondri con un potenziale di membrana alterato, con conseguente alterazione della funzionalità di tale organello, pur conservando l'integrità del DNA mitocondriale.

Valutazione del rischio ecologico e sviluppo di strategie innovative per il monitoraggio della qualita’ dei corpi idrici: applicazione di un nuovo approccio integrato in un bacino pilota.

Freshwater is extremely precious; but even more precious than freshwater is clean freshwater. From the time that 2/3 of our planet is covered in water, we have contaminated our globe with chemicals that have been used by industrial activities over the last century in a unprecedented way causing harm to humans and wildlife. We have to adopt a new scientific mindset in order to face this problem so to protect this important resource. The Water Framework Directive (European Parliament and the Council, 2000) is a milestone legislative document that transformed the way that water quality monitoring is undertaken across all Member States by introducing the Ecological and Chemical Status. A “good or higher” Ecological Status is expected to be achieved for all waterbodies in Europe by 2015. Yet, most of the European waterbodies, which are determined to be at risk, or of moderate to bad quality, further information will be required so that adequate remediation strategies can be implemented. To date, water quality evaluation is based on five biological components (phytoplankton, macrophytes and benthic algae, macroinvertebrates and fishes) and various hydromorphological and physicochemical elements. The evaluation of the chemical status is principally based on 33 priority substances and on 12 xenobiotics, considered as dangerous for the environment. This approach takes into account only a part of the numerous xenobiotics that can be present in surface waters and could not evidence all the possible causes of ecotoxicological stress that can act in a water section. The mixtures of toxic chemicals may constitute an ecological risk not predictable on the basis of the single component concentration. To improve water quality, sources of contamination and causes of ecological alterations need to be identified. On the other hand, the analysis of the community structure, which is the result of multiple processes, including hydrological constrains and physico-chemical stress, give back only a “photograph” of the actual status of a site without revealing causes and sources of the perturbation. A multidisciplinary approach, able to integrate the information obtained by different methods, such as community structure analysis and eco-genotoxicological studies, could help overcome some of the difficulties in properly identifying the different causes of stress in risk assessment. In synthesis, the river ecological status is the result of a combination of multiple pressures that, for management purposes and quality improvement, have to be disentangled from each other. To reduce actual uncertainty in risk assessment, methods that establish quantitative links between levels of contamination and community alterations are needed. The analysis of macrobenthic invertebrate community structure has been widely used to identify sites subjected to perturbation. Trait-based descriptors of community structure constitute a useful method in ecological risk assessment. The diagnostic capacity of freshwater biomonitoring could be improved by chronic sublethal toxicity testing of water and sediment samples. Requiring an exposure time that covers most of the species’ life cycle, chronic toxicity tests are able to reveal negative effects on life-history traits at contaminant concentrations well below the acute toxicity level. Furthermore, the responses of high-level endpoints (growth, fecundity, mortality) can be integrated in order to evaluate the impact on population’s dynamics, a highly relevant endpoint from the ecological point of view. To gain more accurate information about potential causes and consequences of environmental contamination, the evaluation of adverse effects at physiological, biochemical and genetic level is also needed. The use of different biomarkers and toxicity tests can give information about the sub-lethal and toxic load of environmental compartments. Biomarkers give essential information about the exposure to toxicants, such as endocrine disruptor compounds and genotoxic substances whose negative effects cannot be evidenced by using only high-level toxicological endpoints. The increasing presence of genotoxic pollutants in the environment has caused concern regarding the potential harmful effects of xenobiotics on human health, and interest on the development of new and more sensitive methods for the assessment of mutagenic and cancerogenic risk. Within the WFD, biomarkers and bioassays are regarded as important tools to gain lines of evidence for cause-effect relationship in ecological quality assessment. Despite the scientific community clearly addresses the advantages and necessity of an ecotoxicological approach within the ecological quality assessment, a recent review reports that, more than one decade after the publication of the WFD, only few studies have attempted to integrate ecological water status assessment and biological methods (namely biomarkers or bioassays). None of the fifteen reviewed studies included both biomarkers and bioassays. The integrated approach developed in this PhD Thesis comprises a set of laboratory bioassays (Daphnia magna acute and chronic toxicity tests, Comet Assay and FPG-Comet) newly-developed, modified tacking a cue from standardized existing protocols or applied for freshwater quality testing (ecotoxicological, genotoxicological and toxicogenomic assays), coupled with field investigations on macrobenthic community structures (SPEAR and EBI indexes). Together with the development of new bioassays with Daphnia magna, the feasibility of eco-genotoxicological testing of freshwater and sediment quality with Heterocypris incongruens was evaluated (Comet Assay and a protocol for chronic toxicity). However, the Comet Assay, although standardized, was not applied to freshwater samples due to the lack of sensitivity of this species observed after 24h of exposure to relatively high (and not environmentally relevant) concentrations of reference genotoxicants. Furthermore, this species demonstrated to be unsuitable also for chronic toxicity testing due to the difficult evaluation of fecundity as sub-lethal endpoint of exposure and complications due to its biology and behaviour. The study was applied to a pilot hydrographic sub-Basin, by selecting section subjected to different levels of anthropogenic pressure: this allowed us to establish the reference conditions, to select the most significant endpoints and to evaluate the coherence of the responses of the different lines of evidence (alteration of community structure, eco-genotoxicological responses, alteration of gene expression profiles) and, finally, the diagnostic capacity of the monitoring strategy. Significant correlations were found between the genotoxicological parameter Tail Intensity % (TI%) and macrobenthic community descriptors SPEAR (p<0.001) and EBI (p<0.05), between the genotoxicological parameter describing DNA oxidative stress (ΔTI%) and mean levels of nitrates (p<0.01) and between reproductive impairment (Failed Development % from D. magna chronic bioassays) and TI% (p<0.001) as well as EBI (p<0.001). While correlation among parameters demonstrates a general coherence in the response to increasing impacts, the concomitant ability of each single endpoint to be responsive to specific sources of stress is at the basis of the diagnostic capacity of the integrated approach as demonstrated by stations presenting a mismatch among the different lines of evidence. The chosen set of bioassays, as well as the selected endpoints, are not providing redundant indications on the water quality status but, on the contrary, are contributing with complementary pieces of information about the several stressors that insist simultaneously on a waterbody section providing this monitoring strategy with a solid diagnostic capacity. Our approach should provide opportunities for the integration of biological effects into monitoring programmes for surface water, especially in investigative monitoring. Moreover, it should provide a more realistic assessment of impact and exposure of aquatic organisms to contaminants. Finally this approach should provide an evaluation of drivers of change in biodiversity and its causalities on ecosystem function/services provision, that is the direct and indirect contributions to human well-being.

Pathological changes in the primary visual cortex (Area V1) in Creutzfeldt-Jakob syndrome

About 10% of patients with Creutzfeldt-Jakob syndrome (disease) (CJD) exhibit visual symptoms at presentation and approximately 50% during the course of the disease. The objectives of the present study were to determine, in two subtypes of CJD, viz., sporadic CJD (sCJD) and variant CJD (vCJD), the degree of pathological change in the primary visual cortex (area V1) and the extent to which pathology in V1 may influence visual function. The vacuolation (‘spongiform change’), surviving neurons, glial cell nuclei, and deposits of prion protein (PrP) were quantified in V1 obtained post-mortem in nine cases of sCJD and eleven cases of vCJD. In sCJD, the vacuoles and PrP deposits were regularly distributed along the cortex parallel to the pia mater in clusters with a mean dimension from 450 to 1000 µm. Across the cortex, the vacuolation was most severe in laminae II/III and the glial cell reaction in laminae V/VI. Surviving neurons were most abundant in laminae II/III while PrP deposition either affected all laminae equally or was maximal in lamina II/III. In vCJD, the vacuoles and diffuse PrP deposits were distributed relatively uniformly parallel to the pia mater while the florid deposits were consistently distributed in regular clusters. Across V1, the vacuoles either exhibited a bimodal distribution or were uniformly distributed. The diffuse PrP deposits occurred most frequently in laminae II/III while the florid deposits were more generally distributed. The data suggest that in both sCJD and vCJD, pathological changes in area V1 may affect the processing of visual information in laminae II/III and its transmission from V1 to V2 and to subcortical visual areas. In addition, the data suggest an association in sCJD between the developing pathology and the functional domains of V1 while in vCJD the pathology is more uniformly distributed. These changes could be a factor in the development of poor visual acuity, visual field defects, cortical blindness, diplopia, and vertical gaze palsy that have been observed in Creutzfeldt-Jakob syndrome.

Modelling the growth of prion protein aggregates in the brain in variant Creutzfeldt-Jakob disease

Deposition of insoluble prion protein (PrP) in the brain in the form of protein aggregates or deposits is characteristic of the ‘transmissible spongiform encephalopathies’ (TSEs). Understanding the growth and development of these PrP aggregates is important both in attempting to the elucidate of the pathogenesis of prion disease and in the development of treatments designed to prevent or inhibit the spread of prion pathology within the brain. Aggregation and disaggregation of proteins and the diffusion of substances into the developing aggregates (surface diffusion) are important factors in the development of protein aggregates. Mathematical models suggest that if aggregation/disaggregation or surface diffusion is the predominant factor, the size frequency distribution of the resulting protein aggregates in the brain should be described by either a power-law or a log-normal model respectively. This study tested this hypothesis for two different types of PrP deposit, viz., the diffuse and florid-type PrP deposits in patients with variant Creutzfeldt-Jakob disease (vCJD). The size distributions of the florid and diffuse plaques were fitted by a power-law function in 100% and 42% of brain areas studied respectively. By contrast, the size distributions of both types of plaque deviated significantly from a log-normal model in all brain areas. Hence, protein aggregation and disaggregation may be the predominant factor in the development of the florid plaques. A more complex combination of factors appears to be involved in the pathogenesis of the diffuse plaques. These results may be useful in the design of treatments to inhibit the development of protein aggregates in vCJD.

Reforming the social housing waiting game

The UK’s social housing stock is a precious resource that needs to be allocated as fairly and transparently as possible, says Ed Turner, who highlights inadequacies in the current approach and argues for two major changes to the way social housing is allocated and the support councils give those in housing needed.

The influence of bird droppings and uric acid on the radial growth of five species of saxicolous lichens

Bird droppings were applied over 1 year as a thick paste and as a suspension in deionized water to five species of lichens with different distributions on and off bird perching stones. The paste and suspension increased the radial growth of Parmelia conspersa while the paste increased the growth of Xanthoria parietina and reduced the growth and caused loss of colour in Parmelia glabratula ssp. fuliginosa. There were no statistically significant effects of paste or suspension on the growth of Physcia grisea or Parmelia saxatilis. In P. conspersa and X. parietina the growth responses were similar through the year but in P. glabratula the inhibitory effect of the paste was significant after 8 months growth. Application of a suspension of uric acid over 1 year had no statistically significant effects on the growth of P. conspersa, P. glabratula or X. parietina and was unlikely to be responsible for the effects of bird droppings on growth. The growth responses of the five species agreed well with their distributions in the field.

The evaluation and development of the lead authority partnership scheme as a central intervention strategy for health and safety enforcement by local authorities

The research comprises a suite of studies that examines and develops the Lead Authority Partnership Scheme (LAPS) as a central intervention strategy for health and safety by local authority (LA) enforcers. Partnership working is a regulatory concept that in recent years has become more popular but there has been little research conducted to investigate, explore and evaluate its practical application. The study reviewed two contrasting approaches to partnership working between LAs and businesses, both of which were intended to secure improvements in the consistency of enforcement by the regulators and in the health and safety management systems of the participating businesses. The first was a well-established and highly prescriptive approach that required a substantial resource commitment on the part of the LA responsible for conducting a safety management review (SMR) of the business. As a result of his evaluation of the existing ‘full SMR’ scheme, the author developed a second, more flexible approach to partnership working. The research framework was based upon a primarily qualitative methodology intended to investigate and explore the impact of the new flexible arrangements for partnership working. The findings from this study of the flexible development of the scheme were compared and contrasted with those from studies of the established ‘full SMR’ scheme. A substantial degree of triangulation was applied in an attempt to strengthen validity and broaden applicability of the research findings. Key informant interviews, participant observation, document/archive reviews, questionnaires and surveys all their particular part to play in the overall study. The findings from this research revealed that LAPS failed to deliver consistency of LA enforcement across multiple-outlet businesses and the LA enforced business sectors. Improvement was however apparent in the safety management systems of the businesses participating in LAPS. Trust between LA inspector and safety professional was key to the success of the partnerships as was the commitment of these key individuals. Competition for precious LA resources, the priority afforded to food safety over health and safety, the perceived high resource demands of LAPS, and the structure and culture of LAs were identified as significant barriers to LA participation. Flexible approaches, whilst addressing the resource issues, introduced some fresh concerns relating to credibility and delivery. Over and above the stated aims of the scheme, LAs and businesses had their own reasons for participation, notably the personal development of individuals and kudos for the organisation. The research has explored the wider implications for partnership working with the overall conclusion it is most appropriately seen as a strategic level element within a broader structured intervention strategy.

A study in the reduction of efficiency of nitrogen oxide removal catalysts for automobiles

Automotive catalysts are the most effective short-term answer to air pollution from automobiles. Since strict control of exhaust emissions is, or will be,covered by legislation in most developed countries in the world, catalytic devices will be increasingly fitted to cars. There is consequently an urgent need for the development of catalysts that will not compete for scarce precious metal resources. A number of problems have already been identified in connection with base metal catalysts but quantitative investigations are lacking. The base metal reduction catalysts developed by Imperial Chemical Industries Limited, catalysts and Chemical Group, in collaboration with the Air Pollution Control Laboratory, B L Cars Limited for automotive emission control, are susceptible to de-activation by three major mechanisms. These are: physical loss of the wash-coat (a high surface area coating which supports the active species), aggregation of the active species and poisoning by fuel and engine oil additives. This thesis is especially concerned with the first two of these and attempts to indicate the relative magnitude .of their effect on the activity of. the catalysts. Aggregation of the active species or sintering, as it is loosely called, was studied by using impregnated granules to overcome effects due to the loss of the wash-coat. Samples were aged in a synthetic exhaust gas, free from poisons, and metal crystallite sizes were measured by scanning-electron microscopy. The increase in particle size was correlated with the loss in catalytic activity. In order to maintain a link with the real conditions of service a number of monolithic catalysts were tested in an engine-dynamometer and several previously tested endurance catalysts were examined. A mechanism is proposed for the break-up and subsequent 10s.5 of the wash-coat and suggestions for improved resistance to loss of the' coating and active species are proposed.

Sensing and control of adipocyte function

Obesity has become a global epidemic. Approximately 15% of the world population is either overweight or obese. This figure rises to 75% in many westernised countries including the United Kingdom. Health costs in the UK to treat obesity and associated disease are conservatively estimated at 6% of the National Health Service (NHS) budget equating to 3.33 billion Euros. Excess adiposity, especially in visceral depots, increases the risk of type 2 diabetes, cardiovascular disease, gall stones, hypertension and cancer. Type 2 diabetes mellitus accounts for >90% of all cases of diabetes of which the majority can be attributed to increased adiposity, and approximately 70% of cardiovascular disease has been attributed to obesity in the US. Weight loss reduces risk of these complications and in some cases can eliminate the condition. However, weight loss by conventional non-medicated methods is often unsuccessful or promptly followed by weight regain. This thesis has investigated adipocytes development and adipokine signalling with a view to enhance the understanding of tissue functionality and to identify possible targets or pathways for therapeutic intervention. Adipocyte isolation from human tissue samples was undertaken for these investigative studies, and the methodology was optimised. The resulting isolates of pre-adipocytes and mature adipocytes were characterised and evaluated. Major findings from these studies indicate that mature adipocytes undergo cell division post terminal differentiation. Gene studies indicated that subcutaneous adipose tissue exuded greater concentrations and fluctuations of adipokine levels than visceral adipose tissue, indicating an important adiposensing role of subcutaneous adipose tissue. It was subsequently postulated that the subcutaneous depot may provide the major focus for control of overall energy balance and by extension weight control. One potential therapeutic target, 11ß-hydrosteroid dehydrogenase (11ß-HSD1) was investigated, and prospective inhibitors of its action were considered (BVT1, BVT2 and AZ121). Selective reduction of adiposity of the visceral depot was desired due to its correlation with the detrimental effects of obesity. However, studies indicated that although the visceral depot tissue was not unaffected, the subcutaneous depot was more susceptible to therapeutic inhibition by these compounds. This was determined to be a potentially valuable therapeutic intervention in light of previous postulations regarding long-term energy control via the subcutaneous tissue depot.

An extensive laboratory investigation of the use of bio-oil modified bitumen in road construction

Several roads in Iceland with bio-oil modified surface dressings exhibited severe distresses such as bleeding, binder drain down, and eventually as surface dressing sticking to tires. Samples from six road sections were evaluated in the laboratory to determine the causes of the failure. Binders with and without bio-oil, rapeseed oil and fish oil, were evaluated through a comprehensive rheological and chemical characterization. Both oils, exhibited solubility issues with the bitumen; consequently, the oils covered the aggregates, preventing bonding between binder and stones. It appears that fish oil worked a little better than rapeseed oil for binder modification.

Waste 4:electronic-scrap recycling

The Haloclean process, a rotary kiln process for pyrolysis, developed by researchers at the Forschungszentrum Karlsruhe, Germany makes it possible to recover copper and precious metals from the scrap, ready for recycling. Pyrolysis neatly turns brominated electronic scrap plastics into recyclable copper and methanol feedstock while removing the halogens. The process has demonstrated its ability to recycle brominated electronic scrap in extensive parametric studies. A method suitable for the selective production of HBr in the presence of chlorine is the treatment of the pyrolysis oils with molten polypropylene. This treatment is offers the possibility to use the gas and liquid fraction from pyrolysis of electronic scrap as fossil fuel substitute in copper smelter processes or as feedstock for methanol production via gasification.