Practical and conceptual issues in the use of agent-based modelling for disaster management

Application of agent-based modelling technology (ABM) to disaster management has to date been limited in nature. Existing research has concentrated on extending the model structures and agent architectures of complex algorithms to test robustness and extensibility of this simulation approach. Less attention has been brought to bear on testing the current state-of-the-art in ABM for modelling real-life systems. This thesis aims to take first steps in remedying this gap. It focuses on identifying the practical and conceptual issues which preclude wider utilisation of ABM in disaster management. It identifies that insufficient attention is put on incorporating real-life information and domain knowledge into model definitions. This research first proposes a methodology by which some of these issues may be overcome, and consequently tests and evaluates it through implementation of InSiM (Incident Simulation Model), which depicts reaction of pedestrians to a CBRN (chemical, biological, radiological or nuclear) explosion in a city centre. A number of steps are conducted to obtain real-life information related to human response to CBRN incidents. This information is then used for design and parameterisation of InSiM which is implemented in three configurations. In order to identify the effects use of real-life data have on the simulation results each configuration incorporates the information at different level of complexity. The effects are assessed by comparison of the generated dispersion patterns of agents along the city centre. However, use of conventional statistical goodness-of-fit tests for assessing the degree of the difference was challenged by inhomogeneous nature of the data. Hence, alternative approaches are also adopted so that results can be qualitatively assessed. Nevertheless, the evaluation reveals significant differences at global and local level. This research highlights that incorporation of real-life information and domain knowledge into ABM is not without problems. Each time a problem was addressed, additional issues began to emerge. Most of these challenges were related to generalisation of the complex real-life systems that the model represents. Therefore, further investigations are needed at every methodological step before ABM can fully realise its potential to support disaster management

Resveratrol as Add-on Therapy in Subjects With Well-Controlled Type 2 Diabetes: A Randomized Controlled Trial

Item does not contain fulltextOBJECTIVE: To determine whether resveratrol supplementation can improve insulin sensitivity and promote overall metabolic health on top of standard diabetes care. RESEARCH DESIGN AND METHODS: Seventeen subjects with well-controlled type 2 diabetes (T2D) were treated with placebo and 150 mg/day resveratrol (resVida) in a randomized double-blind crossover study for 30 days. The main outcome measure was insulin sensitivity by the hyperinsulinemic-euglycemic clamp technique. RESULTS: Hepatic and peripheral insulin sensitivity were not affected by resveratrol treatment. Intrahepatic lipid content also remained unaffected by resveratrol; however, the change in intrahepatic lipid content correlated negatively with plasma resveratrol levels (R = -0.68, P = 0.03). Intramyocellular lipid content increased in type 2 muscle fibers (P = 0.03), and systolic blood pressure tended to decrease (P = 0.09) upon resveratrol treatment. In addition, resveratrol significantly improved ex vivo mitochondrial function (state 3 and state U respiration upon malate with octanoyl-carnitine, P < 0.005). Intriguingly, a correlation was found between plasma levels of a metabolite of resveratrol (dihydroresveratrol) and the metformin dose used by the patients (R = 0.66, P = 0.005), suggesting an interaction between metformin and resveratrol. It could be speculated that the lack of a resveratrol-induced insulin-sensitizing effect is caused by this interaction. CONCLUSIONS: Resveratrol supplementation does not improve hepatic or peripheral insulin sensitivity. Our results question the generalized value of resveratrol as an add-on therapy in the treatment of T2D and emphasize the need to perform studies in drug-naive patients with T2D or subjects with prediabetes.1 december 201

Novel Missense Mutation A789V in IQSEC2 underlies X-Linked intellectual disability in the MRX78 family

Disease gene discovery in neurodevelopmental disorders, including X-linked intellectual disability (XLID) has recently been accelerated by next-generation DNA sequencing approaches. To date, more than 100 human X chromosome genes involved in neuronal signaling pathways and networks implicated in cognitive function have been identified. Despite these advances, the mutations underlying disease in a large number of XLID families remained unresolved. We report the resolution of MRX78, a large family with six affected males and seven affected females, showing X-linked inheritance. Although a previous linkage study had mapped the locus to the short arm of chromosome X (Xp11.4-p11.23), this region contained too many candidate genes to be analyzed using conventional approaches. However, our X-chromosome exome resequencing, bioinformatics analysis and inheritance testing revealed a missense mutation (c.C2366T, p.A789V) in IQSEC2, encoding a neuronal GDP-GTP exchange factor for Arf family GTPases (ArfGEF) previously implicated in XLID. Molecular modeling of IQSEC2 revealed that the A789V substitution results in the insertion of a larger side-chain into a hydrophobic pocket in the catalytic Sec7 domain of IQSEC2. The A789V change is predicted to result in numerous clashes with adjacent amino acids and disruption of local folding of the Sec7 domain. Consistent with this finding, functional assays revealed that recombinant IQSEC2A789V was not able to catalyze GDP-GTP exchange on Arf6 as efficiently as wild-type IQSEC2. Taken together, these results strongly suggest that the A789V mutation in IQSEC2 is the underlying cause of XLID in the MRX78 family

Mutation p.R356Q in the Collybistin Phosphoinositide Binding Site Is Associated With Mild Intellectual Disability

The recruitment of inhibitory GABAA receptors to neuronal synapses requires a complex interplay between receptors, neuroligins, the scaffolding protein gephyrin and the GDP-GTP exchange factor collybistin (CB). Collybistin is regulated by protein-protein interactions at the N-terminal SH3 domain, which can bind neuroligins 2/4 and the GABAAR a2 subunit. Collybistin also harbors a RhoGEF domain which mediates interactions with gephyrin and catalyzes GDP-GTP exchange on Cdc42. Lastly, collybistin has a pleckstrin homology (PH) domain, which binds phosphoinositides, such as phosphatidylinositol 3-phosphate (PI3P/PtdIns3P) and phosphatidylinositol 4-monophosphate (PI4P/PtdIns4P). PI3P located in early/sorting endosomes has recently been shown to regulate the postsynaptic clustering of gephyrin and GABAA receptors and consequently the strength of inhibitory synapses in cultured hippocampal neurons. This process is disrupted by mutations in the collybistin gene (ARHGEF9), which cause X-linked intellectual disability (XLID) by a variety of mechanisms converging on disrupted gephyrin and GABAA receptor clustering at central synapses. Here we report a novel missense mutation (chrX:62875607C>T, p.R356Q) in ARHGEF9 that affects one of the two paired arginine residues in the PH domain that were predicted to be vital for binding phosphoinositides. Functional assays revealed that recombinant collybistin CB3SH3-R356Q was deficient in PI3P binding and was not able to translocate EGFP-gephyrin to submembrane microaggregates in an in vitro clustering assay. Expression of the PI3P-binding mutants CB3SH3-R356Q and CB3SH3-R356N/R357N in cultured hippocampal neurones revealed that the mutant proteins did not accumulate at inhibitory synapses, but instead resulted in a clear decrease in the overall number of synaptic gephyrin clusters compared to controls. Molecular dynamics simulations suggest that the p.R356Q substitution influences PI3P binding by altering the range of structural conformations adopted by collybistin. Taken together, these results suggest that the p.R356Q mutation in ARHGEF9 is the underlying cause of XLID in the probands, disrupting gephyrin clustering at inhibitory GABAergic synapses via loss of collybistin PH domain phosphoinositide binding

Practical and conceptual issues in the use of agent-based modelling for disaster management

Application of agent-based modelling technology (ABM) to disaster management has to date been limited in nature. Existing research has concentrated on extending the model structures and agent architectures of complex algorithms to test robustness and extensibility of this simulation approach. Less attention has been brought to bear on testing the current state-of-the-art in ABM for modelling real-life systems. This thesis aims to take first steps in remedying this gap. It focuses on identifying the practical and conceptual issues which preclude wider utilisation of ABM in disaster management. It identifies that insufficient attention is put on incorporating real-life information and domain knowledge into model definitions. This research first proposes a methodology by which some of these issues may be overcome, and consequently tests and evaluates it through implementation of InSiM (Incident Simulation Model), which depicts reaction of pedestrians to a CBRN (chemical, biological, radiological or nuclear) explosion in a city centre. A number of steps are conducted to obtain real-life information related to human response to CBRN incidents. This information is then used for design and parameterisation of InSiM which is implemented in three configurations. In order to identify the effects use of real-life data have on the simulation results each configuration incorporates the information at different level of complexity. The effects are assessed by comparison of the generated dispersion patterns of agents along the city centre. However, use of conventional statistical goodness-of-fit tests for assessing the degree of the difference was challenged by inhomogeneous nature of the data. Hence, alternative approaches are also adopted so that results can be qualitatively assessed. Nevertheless, the evaluation reveals significant differences at global and local level. This research highlights that incorporation of real-life information and domain knowledge into ABM is not without problems. Each time a problem was addressed, additional issues began to emerge. Most of these challenges were related to generalisation of the complex real-life systems that the model represents. Therefore, further investigations are needed at every methodological step before ABM can fully realise its potential to support disaster management.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Resveratrol improves ex vivo mitochondrial function but does not affect insulin sensitivity or brown adipose tissue in first degree relatives of patients with type 2 diabetes

Objective: Resveratrol supplementation improves metabolic health in healthy obese men, but not in patients with type 2 diabetes (T2D) when given as add-on therapy. Therefore, we examined whether resveratrol can enhance metabolic health in men at risk of developing T2D. Additionally, we examined if resveratrol can stimulate brown adipose tissue (BAT). Methods: Thirteen male first degree relatives (FDR) of patients with T2D received resveratrol (150 mg/day) and placebo for 30 days in a randomized, placebo controlled, cross-over trial. Results: Resveratrol significantly improved ex vivo muscle mitochondrial function on a fatty acid-derived substrate. However, resveratrol did not improve insulin sensitivity, expressed as the rate of glucose disposal during a two-step hyperinsulinemic-euglycemic clamp. Also, intrahepatic and intramyocellular lipid content, substrate utilization, energy metabolism, and cold-stimulated 18F-FDG glucose uptake in BAT (n = 8) remained unaffected by resveratrol. In vitro experiments in adipocytes derived from human BAT confirmed the lack of effect on BAT. Conclusions: Resveratrol stimulates muscle mitochondrial function in FDR males, which is in concordance with previous results. However, no other metabolic benefits of resveratrol were found in this group. This could be attributed to subject characteristics causing alterations in metabolism of resveratrol and thereby affecting resveratrol's effectiveness. ClinicalTrials.gov ID: NCT02129595. Keywords: Resveratrol, Type 2 diabetes, Pre-diabetes, Insulin sensitivity, Mitochondrial function, Brown adipose tissu

Effects of SGLT2 inhibitor dapagliflozin in patients with type 2 diabetes on skeletal muscle cellular metabolism

OBJECTIVE: SGLT2 inhibitors increase urinary glucose excretion and have beneficial effects on cardiovascular and renal outcomes; the underlying mechanism may be metabolic adaptations due to urinary glucose loss. Here, we investigated the cellular and molecular effects of 5 weeks of dapagliflozin treatment on skeletal muscle metabolism in type 2 diabetes patients. METHODS: Twenty-six type 2 diabetes mellitus patients were randomized to a 5-week double-blind, cross-over study with 6-8-week wash-out. Skeletal muscle acetylcarnitine levels, intramyocellular lipid (IMCL) content and phosphocreatine (PCr) recovery rate were measured by magnetic resonance spectroscopy (MRS). Ex vivo mitochondrial respiration was measured in skeletal muscle fibers using high resolution respirometry. Intramyocellular lipid droplet and mitochondrial network dynamics were investigated using confocal microscopy. Skeletal muscle levels of acylcarnitines, amino acids and TCA cycle intermediates were measured. Expression of genes involved in fatty acid metabolism were investigated. RESULTS: Mitochondrial function, mitochondrial network integrity and citrate synthase and carnitine acetyltransferase activities in skeletal muscle were unaltered after dapagliflozin treatment. Dapagliflozin treatment increased intramyocellular lipid content (0.060 (0.011, 0.110) %, p = 0.019). Myocellular lipid droplets increased in size (0.03 μm2 (0.01-0.06), p < 0.05) and number (0.003 μm-2 (-0.001-0.007), p = 0.09) upon dapagliflozin treatment. CPT1A, CPT1B and malonyl CoA-decarboxylase mRNA expression was increased by dapagliflozin. Fasting acylcarnitine species and C4-OH carnitine levels (0.4704 (0.1246, 0.8162) pmoles∗mg tissue-1, p < 0.001) in skeletal muscle were higher after dapagliflozin treatment, while acetylcarnitine levels were lower (-40.0774 (-64.4766, -15.6782) pmoles∗mg tissue-1, p < 0.001). Fasting levels of several amino acids, succinate, alpha-ketoglutarate and lactate in skeletal muscle were significantly lower after dapagliflozin treatment. CONCLUSION: Dapagliflozin treatment for 5 weeks leads to adaptive changes in skeletal muscle substrate metabolism favoring metabolism of fatty acid and ketone bodies and reduced glycolytic flux. The trial is registered with ClinicalTrials.gov, number NCT03338855