Detection and fate of engineered nanoparticles in aquatic systems.

The proliferation of nanotechnology has prompted discussions over the safety of these materials to human health and the environment as their environmental fate and impact is widely unknown. This is partly due to the lack of suitable analytical techniques to detect and characterise engineered nanoparticles in the environment. This thesis aims to provide a better understanding of the environmental fate of engineered nanoparticles by developing analytical methods suitable for nanoparticle analysis in aquatic systems and employing these to laboratory-based environmental fate studies

Kardiale Expression der Proteoglykane Biglykan und Decorin: Untersuchungen an kultivierten Fibroblasten neonataler Ratten und an infarzierten Herzen adulter Ratten

Nach Myokardinfarkt (MI) beginnen umfangreiche Umbauprozesse. Neu gebildetes fibrotisches Gewebe sowohl im infarzierten, als auch in den nicht-infarzierten Gebieten beeinträchtigt die Funktion des Muskels. Die myokardiale Fibrosierung wird maßgeblich von Fibroblasten verursacht und ist gekennzeichnet durch eine Vermehrung der EZM, die von Fibroblasten sezerniert wird, akkumuliert und ein dreidimensionales Netzwerk bildet, das zu der Funktionsbeeinträchtigung des Muskels führt. Medizinisch wären Ansätze von Bedeutung, die diese funktionsbeeinträchtigenden Fibrosierungsreaktionen hemmen, setzen aber Kenntnisse der Prozesse und Faktoren voraus, die diese pathologischen Vorgänge hemmen. Anliegen der vorliegenden Arbeit war die Untersuchung verschiedener Reize für Wachstum und Proliferation auf die Synthese von EZM-Bausteinen von kardialen Fibroblasten und inwieweit sich Parallelen zur Situation im Herzen von Ratten nach Infarkt ergeben. Kardiale Fibroblasten wurden aus den Herzen neonataler Ratten gewonnen und immunhistochemisch charakterisiert (Immunfluoreszenz-Mikroskopie). Die PG-Synthese wurde mit Hilfe des Einbaus radioaktiven Sulfats gemessen. Mit dem Verfahren des Northern-Blot wurden Veränderungen auf mRNA-Ebene, mit dem Verfahren der Gel-Filtrations-Chromatographie die Kettenlänge der den PG-angehefteten GAG ermittelt. An den Herzen adulter Ratten nach Infarkt wurde im Infarktbereich selbst, im nicht-infarzierten Septum und rechten Ventrikel die Expression der mRNA für Biglykan (BG) und Decorin (Dec) mit Hilfe der RT-PCR gemessen. Kardiale Fibroblasten synthetisieren hauptsächlich das kleine, leucin-reiche PG BG. PDGF BB, TGF-ß1 sowie Thrombin erhöhten die PG-Sekretion deutlich. Ang II stimulierte, vermittelt durch den Ang II-Rezeptorsubtyp 1 (AT1-Rezeptor), sowohl die Sekretion von PG in das Zellkulturmedium als auch die Expression der BG-mRNA. Weiterhin stimulierte Ang II die TGF-ß1-Freisetzung aus den Fibroblasten. Als Mechanismus für die AT-1-vermittelte BG-Induktion konnte die autokrine Freisetzung von TGF-ß1 wahrscheinlich gemacht werden, da die Stimu-lation der BG-Expression durch Ang II in Gegenwart neutralisierender Anti-TGF-ß-Antikörpern ausblieb. NO unterdrückte in den kardialen Fibroblasten sowohl die PDGF BB-stimulierte Sekretion der PG als auch spezifisch die mRNA-Expression von BG. Zudem erhöhte NO das Molekulargewicht der GAG-Ketten von BG in Kombination mit PDGF BB. Die Untersuchungen zur PG-Synthese fördernden Wirkung des Ang II und ihrer Hemmbarkeit durch Inhibitoren des RAS an kardialen Fibroblasten wurden ergänzt durch Untersuchungen zur Expression der PG Dec und BG im Herz-muskelgewebe adulter Ratten nach Infarkt. Unter dieser Bedingung war die Expression der PG BG und Dec gesteigert, das Maximum der Expression wurde am 5.-7., bzw. 3.-5. Tag nach MI erreicht. Obgleich Ang II nachweisbar die BG-Synthese erhöhte, erwies sich die Behandlung der Tiere mit Hemmstoffen des RAS als wirkungslos. Die Wirkungslosigkeit von Hemmstoffen des RAS stellt nicht unbedingt eine Widerspruch zu den in vitro Befunden dar, mag sich vielmehr aus der Anwesenheit anderer die PG-Synthese maßgeblich beeinflussender Faktoren unter den in vivo Bedingungen erklären

Physiological normoxia and absence of EGF is required for the long-term propagation of anterior neural precursors from human pluripotent cells

Widespread use of human pluripotent stem cells (hPSCs) to study neuronal physiology and function is hindered by the ongoing need for specialist expertise in converting hPSCs to neural precursor cells (NPCs). Here, we describe a new methodology to generate cryo-preservable hPSC-derived NPCs that retain an anterior identity and are propagatable long-term prior to terminal differentiation, thus abrogating regular de novo neuralization. Key to achieving passagable NPCs without loss of identity is the combination of both absence of EGF and propagation in physiological levels (3%) of O2. NPCs generated in this way display a stable long-term anterior forebrain identity and importantly retain developmental competence to patterning signals. Moreover, compared to NPCs maintained at ambient O2 (21%), they exhibit enhanced uniformity and speed of functional maturation, yielding both deep and upper layer cortical excitatory neurons. These neurons display multiple attributes including the capability to form functional synapses and undergo activity-dependent gene regulation. The platform described achieves long-term maintenance of anterior neural precursors that can give rise to forebrain neurones in abundance, enabling standardised functional studies of neural stem cell maintenance, lineage choice and neuronal functional maturation for neurodevelopmental research and disease-modelling

Detection and fate of engineered nanoparticles in aquatic systems

The proliferation of nanotechnology has prompted discussions over the safety of these materials to human health and the environment as their environmental fate and impact is widely unknown. This is partly due to the lack of suitable analytical techniques to detect and characterise engineered nanoparticles in the environment. This thesis aims to provide a better understanding of the environmental fate of engineered nanoparticles by developing analytical methods suitable for nanoparticle analysis in aquatic systems and employing these to laboratory-based environmental fate studies.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A uniform measurement expression for cross method comparison of nanoparticle aggregate size distributions

The European Commission’s recent recommendation for a definition nanomaterials (2011/696/EU) will require characterisation of materials used in regulated consumer products in terms of number based particle concentration and size distribution. When adopted under food regulations, the definition will be applicable to those food additives that contain a fraction of the particles that are smaller than 100 nm at or above the threshold of 50% in terms of particle number based size distribution. In the view of this we have performed a comparative evaluation of the different analytical methods for the measurement of number based particle size distributions. This study has used synthetic amorphous silica as a an example nano-structured material already widely applied in food processing, and provides a comparison of the six methods deemed suitable for the purpose: scanning electron microscopy in both high vacuum and liquid cell setup; gas-phase electrophoretic mobility molecular analyser; centrifugal liquid sedimentation; nanoparticle tracking analysis; and asymmetric flow field flow fractionation on-line combined with plasma mass spectrometry. The results have highlighted an important question in relation to the effects that the particle shape, chemical composition and agglomeration/aggregation state may have on the size measurement accuracy of the different methods. We propose mass equivalent diameter (MED) as a uniform expression of particle size distribution measurements for aggregated particulate materials allowing comparison of the measurements from different analytical methods. We have detailed how the MED for aggregated materials, such as synthetic amorphous silica, can be derived from measurements by the six methods. This approach enables unambiguous interpretation and comparison of the results between different research studies on nanoparticles and reference materials, and is our best suggestion for a common measure of particle size distributions.JRC.D.2-Standards for Innovation and sustainable Developmen

A uniform measurement expression for cross method comparison of nanoparticle aggregate size distributions

Measurement methods produce incomparable results when applied to aggregated nanoparticles.</p

Analysing the fate of nanopesticides in soil and the applicability of regulatory protocols using a polymer-based nanoformulation of atrazine

For the first time, regulatory protocols defined in the OECD guidelines were applied to determine the fate properties of a nanopesticide in two agricultural soils with contrasting characteristics. The nanoformulation studied had no effect on the degradation kinetics of atrazine indicating that (1) the release of atrazine from the polymer nanocarriers occurred rapidly relative to the degradation kinetics (half-lives 36-53 days) and/or that (2) atrazine associated with the nanocarriers was subject to biotic or abiotic degradation. Sorption coefficients, derived from a batch and a centrifugation technique at a realistic soil-to-solution ratio, were higher for the nanoformulated atrazine than for the pure active ingredient. Results indicate that the nanoformulation had an effect on the fate of atrazine. However, since the protocols applied were designed to assess solutes, conclusions about the transport of atrazine loaded onto the nanocarriers should be made extremely cautiously. The centrifugation method applied over time (here over 7 days) appears to be a useful tool to indirectly assess the durability of nanopesticides under realistic soil-to-solution ratios and estimate the period of time during which an influence on the fate of the active ingredient may be expected. More detailed investigations into the bioavailability and durability of nanopesticides are necessary and will require the development of novel methods suitable to address both the "nano" and "organic" characteristics of polymer-based nanopesticides

Acrocomia spp.: neglected crop, ballyhooed multipurpose palm or fit for the bioeconomy? A review

International audienceAcrocomia spp., a genus of wild-growing palms in the neotropics, is rapidly gaining interest as a promising multipurpose crop. Diverse products can be derived from various components of the palm, the oils being of highest interest. Acrocomia shows similar oil yield and fatty acid composition to the African oil palm (Elaeis guineensis). It is, however, able to cope with a wider range of environmental conditions, including temporary water scarcity and lower temperatures, thus potentially a more sustainable alternative to its tropical counterpart. Acrocomia’s research history is recent compared to other traditional crops and thus knowledge gaps, uncertainty, and challenges need to be addressed. This review attempts to assess the acrocomia’s preparedness for cultivation by highlighting the state-of-the-art in research and identifying research gaps. Based on a systematic literature search following a value web approach, it (a) provides a comprehensive overview of research topics, (b) shows the development of publication activities over time and the drivers of this development, and (c) compiles main findings to assess the acrocomia’s preparedness for commercial cultivation. Our results confirm its multipurpose characteristic as a potential feedstock for manifold sectors. Research has continued to increase over the last decade, especially on A. aculeata and is driven by the interest in bioenergy. Increasing knowledge on botany has contributed to understanding the genetic diversity and genus-specific biology. This has enabled applied research on seed germination and propagation toward domestication and initial plantation activities, mostly in Brazil. Main research gaps are associated with genotype–environment interaction, planting material, crop management, and sustainable cropping systems. Overall, we conclude that acrocomia is at an early phase of development as an alternative and multipurpose crop and its up-scaling requires the integration of sustainability strategies tailored to location-based social-ecological conditions