Post Longford gas plant disaster: a study of competence as a major element of safety case analysis in the petrochemical industry

Master of EducationOn the 25th September 1998 two plant operators were killed and a further eight operators were seriously injured when the Longford Gas Plant exploded and caught on fire. The Royal Commission that followed this disaster identified inadequate operator training and operator incompetence as a significant causal factor that contributed to this disaster. This study investigates the nature of process plant operator competence in the petrochemical industry in the `post Longford' environment. This study used qualitative research methods to study operator competence, specifically document analysis and in-depth interviews with plant operators and training managers. Data from the document analysis and interview transcripts were collected and analysed with a view to improving understanding of the factors that contribute to operator competence. The findings of this study indicated that operator competence involves formal learning and also informal and tacit knowledge that is learnt in `communities of practice' where experienced operators mentor and guide less experienced members of the shift team. This study suggests that genuine operator competence involves more than just an ability to manage routine duties but also involves an ability to respond effectively during non-routine situations and plant emergencies - these crises have the potential for catastrophic consequences if poorly managed. This study found that there are significant opportunities to improve the training strategies and the organisational support structures to enhance operator competence. This study has made a number of recommendations to improve the competence of petrochemical plant operators. A theoretical model has also been developed to enhance plant operator competence in the petrochemical industry. Suggestions for future research into the area of plant operator competence have been suggested

Detecting molecular interactions in live-cell single-molecule imaging with proximity-assisted photoactivation (PAPA).

Single-molecule imaging provides a powerful way to study biochemical processes in live cells, yet it remains challenging to track single molecules while simultaneously detecting their interactions. Here, we describe a novel property of rhodamine dyes, proximity-assisted photoactivation (PAPA), in which one fluorophore (the 'sender') can reactivate a second fluorophore (the 'receiver') from a dark state. PAPA requires proximity between the two fluorophores, yet it operates at a longer average intermolecular distance than Förster resonance energy transfer (FRET). We show that PAPA can be used in live cells both to detect protein-protein interactions and to highlight a subpopulation of labeled protein complexes in which two different labels are in proximity. In proof-of-concept experiments, PAPA detected the expected correlation between androgen receptor self-association and chromatin binding at the single-cell level. These results establish a new way in which a photophysical property of fluorophores can be harnessed to study molecular interactions in single-molecule imaging of live cells

Synthesis and characterization of high affinity fluorogenic α-synuclein probes

Fluorescent small molecules are powerful tools for imaging α-synuclein pathology in vitro and in vivo. In this work, we explore benzofuranone as a potential scaffold for the design of fluorescent α-synuclein probes. These compounds have high affinity for α-synuclein, show fluorescent turn-on upon binding to fibrils, and display different binding to Lewy bodies, Lewy neurites and glial cytoplasmic inclusion pathologies in post-mortem brain tissue. These studies not only reveal the potential of benzofuranone compounds as α-synuclein specific fluorescent probes, but also have implications for the ways in which α-synucleinopathies are conformationally different and display distinct small molecule binding sites

Linkage analysis between childhood absence epilepsy and genes encoding GABAA and GABAB receptors, voltage-dependent calcium channels, and the ECA1 region on chromosone 8q

Childhood absence epilepsy (CAE) is an idiopathic generalised epilepsy (IGE) characterised by onset of typical absence seizures in otherwise normal children of school age. A genetic component to aetiology is well established but the mechanism of inheritance and the genes involved are unknown. Available evidence suggests that mutations in genes encoding GABA receptors or brain expressed voltage-dependent calcium channels (VDCCs) may underlie CAE. The aim of this work was to test this hypothesis by linkage analysis using microsatellite loci spanning theses genes in 33 nuclear families each with two or more individuals with CAE. Seventeen VDCC subunit genes, ten GABA(A)R subunit genes, two GABA(B) receptor genes and the ECA1 locus on 8q24 were investigated using 35 microsatellite loci. Assuming locus homogeneity, all loci gave statistically significant negative LOD scores, excluding these genes as major loci in the majority of these families. Positive HLOD scores assuming locus heterogeneity were observed for CACNG3 on chromosome 16p12-p13.1 and the GABRA5, GABRB3, GABRG3 cluster on chromosome 15q11-q13. Association studies are required to determine whether these loci are the site of susceptibility alleles in a subset of patients with CAE

Identification of a nanomolar affinity a-synuclein fibril imaging probe by ultra-high throughput: In silico screening

Small molecules that bind with high affinity and specificity to fibrils of the a-synuclein (aS) protein have the potential to serve as positron emission tomography (PET) imaging probes to aid in the diagnosis of Parkinson's disease and related synucleinopathies. To identify such molecules, we employed an ultra-high throughput in silico screening strategy using idealized pseudo-ligands termed exemplars to identify compounds for experimental binding studies. For the top hit from this screen, we used photo-crosslinking to confirm its binding site and studied the structure-activity relationship of its analogs to develop multiple molecules with nanomolar affinity for aS fibrils and moderate specificity for aS over Aß fibrils. Lastly, we demonstrated the potential of the lead analog as an imaging probe by measuring binding to aS-enriched homogenates from mouse brain tissue using a radiolabeled analog of the identified molecule. This study demonstrates the validity of our powerful new approach to the discovery of PET probes for challenging molecular targets

Alpha Synuclein Fibrils Contain Multiple Binding Sites for Small Molecules

The fibrillary aggregation of the protein alpha synuclein (Asyn) is a hallmark of Parkinson’s disease, and the identification of small molecule binding sites on fibrils is essential to the development of diagnostic imaging probes. A series of molecular modeling, photoaffinity labeling, mass spectrometry, and radioligand binding studies were conducted on Asyn fibrils. The results of these studies revealed the presence of three different binding sites within fibrillar Asyn capable of binding small molecules with moderate to high affinity. A knowledge of the amino acid residues in these binding sites will be important in the design of high affinity probes capable of imaging fibrillary species of Asyn

Design, synthesis, and characterization of I-BET567, a pan-bromodomain and extra terminal (BET) bromodomain oral candidate

Through regulation of the epigenome, the bromodomain and extra terminal (BET) family of proteins represent important therapeutic targets for the treatment of human disease. Through mimicking the endogenous N-acetyl-lysine group and disrupting the protein–protein interaction between histone tails and the bromodomain, several small molecule pan-BET inhibitors have progressed to oncology clinical trials. This work describes the medicinal chemistry strategy and execution to deliver an orally bioavailable tetrahydroquinoline (THQ) pan-BET candidate. Critical to the success of this endeavor was a potency agnostic analysis of a data set of 1999 THQ BET inhibitors within the GSK collection which enabled identification of appropriate lipophilicity space to deliver compounds with a higher probability of desired oral candidate quality properties. SAR knowledge was leveraged via Free–Wilson analysis within this design space to identify a small group of targets which ultimately delivered I-BET567 (27), a pan-BET candidate inhibitor that demonstrated efficacy in mouse models of oncology and inflammation