Characterising the matrix of primitive meteorites using electron backscatter diffraction

Imperial Users onl

Investigation of the effects of injury upon intracellular signalling pathways and expression of inflammatory response genes in articular cartilage

Damage to joints predisposes to osteoarthritis. The mechanism by which injury to cartilage might lead to net matrix loss and cartilage degeneration remains unknown. Following experimental sharp injury to porcine articular cartilage (dissection from, or scoring of the articular surface), our group has previously shown rapid activation of the 3 mitogen activated protein kinase (MAPK) pathways in cartilage. Activation of ERK, and probably also p38 MAPK, is due to release of fibroblast growth factor (FGF) from the matrix after injury. However, despite a long search, the cause of JNK activation following sharp injury remains unknown. I investigated the extent and regulation of inflammatory signalling after cartilage injury and whether it was sufficient to cause expression of inflammatory response genes. In this work, I show that a number of intracellular signalling pathways including PI3 kinase and IκB kinase (IKK) (which leads to activation of NFκB) are activated by sharp injury to cartilage. The signalling following injury was sufficient to induce a wide range of inflammatory response mRNAs, including pro-inflammatory cytokines such as IL-6, COX-2 and proteinases such as MMP-1 and ADAMTS-4 in a pattern which was not entirely IL-1-like. Pharmacological inhibition experiments suggested that the production by injured cartilage of an inflammatory response gene which could be assayed at the protein level, activin A, was regulated by FGF-mediated pathways (ERK) as well as by NFκB and tyrosine kinases (src family kinases). Given these findings, the role of tyrosine kinases in the early response of cartilage to injury was explored. By phosphotyrosine immunoprecipitation and purification from injured cartilage lysates, FAK and its substrate paxillin were identified from silverstained gels by mass spectrometry. The phosphorylation of these src substrates accounted for rapidly inducible bands seen on phosphotyrosine western blotting of injured cartilage lysates. However, no evidence of a role for src kinases in the regulation of MAPK/IKK signalling upon injury was found. In contrast, blockade of another tyrosine kinase, the FGF receptor, led to partial inhibition not only of the ERK pathway following sharp injury, but also the other MAPKs and IKK. Whilst activation of the same pathways was also seen following injury to synovium, FGF receptor inhibition had no effect on this signalling. This suggested that FGF may have a pro-inflammatory action following injury in vivo which is a particular feature of cartilage

Effects of copper, zinc and cadmium on the pigments and photosynthesis of black spruce (Picea mariana (Mill.) B.S.P) seedlings

The purpose of this study was to quantify the effects of heavy metals on pigments and photosynthesis in four and a half month old black spruce (Picea mariana (Mill.) B.S.P.) seedlings. Photosynthetic pigment analysis by HPLC and reflectance red edge methods were compared to chi a fluorescence and net oxygen evolution measurements to assess their effectiveness in diagnosing plant stress. Copper, zinc and cadmium were applied as 0, 10 and 20 mM Cu(N03)2, Zn (N03)2 and Cd(N03)2, for 214 weeks. Response to the treatments was examined by measuring pigment content, reflectance red edge, (see document) net oxygen evolution, net water content and needle element content. No treatment differences were found for pigment content or red edge. In contrast, (see document) of seedlings treated with 20 mM Cd was significantly lower than all other treatments and net oxygen evolution decreased m metal-treated seedlings compared to untreated control seedlings. Net water content did not differ between treatments. Needle element content did not change, except for increases m Cu, Zn and Cd in the seedlings treated with these elements. It was concluded that pigment content was unaffected by the treatments but that photosynthetic efficiency (i.e. oxygen evolved) decreased. Possible explanations include inhibition of enzyme activity by Cu2+, Zn2+ and Cd2+, or overloading of defense mechanisms, such as phytochelatins. The use of HPLC analysis of pigments and remote spectroradiometry may prove useful in assessing seedling quality

Using and Understanding Power in Psychological Research: A Survey Study

Statistical power is key to planning studies if understood and used correctly. Power is the probability of obtaining a statistically significant p-value, given a set alpha, sample size, and population effect size. The literature suggests that psychology studies are underpowered due to small sample sizes, and that researchers do not hold accurate intuitions about sensible sample sizes and associated levels of power. In this study, we surveyed 214 psychological researchers, and asked them about their experiences of using a priori power analysis, effect size estimation methods, post hoc power, and their understanding of what the term “power” actually means. Power analysis use was high, although participants reported difficulties with complex research designs, and effect size estimation. Participants also typically could not accurately define power. If psychological researchers are expected to compute a priori power analyses to plan their research, clearer educational material and guidelines should be made available

A New Approach to the Synthesis of Conjugated Polymer: Nanocrystal Composites for Heterojunction Optoelectronics

We report a simple one pot process for the preparation of lead sulphide (PbS) nanocrystals in the conjugated polymer MEH-PPV, and we demonstrate electronic coupling between the two components.Comment: 3 pages, 2 figures, accepted Chem. Comm

Parental Perceptions of Independence and Efficacy of their Children with Visual Impairments

Raising any child to become successful and self-sufficient presents challenges to all parents; however, the complexity of the decision-making in parenting may become more intricate for parents of children with visual impairments. It can be a challenge determining the balance between intense overprotection for reasons of safety versus the encouragement and attention to the participation in unique or challenging learning experiences. Parents of children with visual impairments may also struggle to find the fine line between viewing the child through he lens of the impairment (as other or less than) versus treating the child in the same manner other children are treated in relation to expectations and independence. The need to protect or limit the child with a visual impairment may be present in spite of awareness of the strong connection between experiences in physical and social activities as a means to develop self-determination, and independence. As for all children, for children with visual impairments, parental overprotection and the limiting of experiential activities can have negative implications on the degree of their children’s psychological-emotional and physical well-being sufficient to the development of optimal levels of independence and self-sufficiency. The purpose of this study was to examine the perceptions of parents and primary care-providers of this special population regarding their child’s ability to engage the environment independently (independence) and the degree to which the parents feel required to intervene in the oversight of their child’s activities various experiences (perceived efficacy). Survey results indicated that parents of children with visual impairments are not a monolithic group in terms of their perceptions of their children’s independence or in their perceptions of their child’s efficacy. Recommendations for future research address the need to consider implications for parenting, parent education, and the role of teachers of children with visual impairments, and orientation and mobility specialist