Mitochondrial permeability transition following calcium overload. - Its role in neuronal cell death and potential as a pharmacological target.

There is currently no clinically available drug with neuroprotective properties to limit the evolving cell death following e.g. stroke or traumatic brain injury. The mitochondrial permeability transition (mPT) is a potential pathological mechanism causing cell death in the CNS. As the name implies, the mPT is defined by a sudden increase in permeability of the inner mitochondrial membrane, whose normal impermeable state is fundamental for the bioenergetic function of mitochondria. The objective of the present studies was to characterize the mPT phenomenon in isolated rodent brain mitochondria. Mitochondria serve an important role in cellular calcium homeostasis and buffer transient increases in calcium, but mitochondrial calcium overload is also the prime trigger for mPT. In the present studies, we found that brain mitochondria readily undergo changes attributable to mPT induction such as swelling, loss of membrane potential, uncoupling of oxidative phosphorylation and respiratory inhibition. The mitochondrial generation of reactive oxygen species (ROS) was also increased following mPT, and mitochondria became permeable to NAD(H). Cyclosporin A (CsA) binds to the mitochondrial protein cyclophilin D (CypD) and can thereby inhibit mPT, an effect that is unrelated to its immunosuppressive action, and mPT in brain mitochondria was found to be highly sensitive to CsA inhibition. CsA has demonstrated prominent neuroprotective properties in several different animal models of neurological disease, and recent experiments subjecting mice lacking CypD to ischemia support the conclusion that the effect of CsA at least in this model is mediated by mPT inhibition. A library of CsA analogs was evaluated for mPT-inhibiting and ROS-reducing properties, and two newly developed non-immunosuppressive CsA analogs were found to be potent inhibitors of mPT already at nanomolar concentrations. Mitochondria take up free calcium ions but retain them as inactive calcium phosphate complexes in order to prevent mPT. We find that increasing the conductance of potassium increases the pH of the matrix and this enhances the mitochondrial buffering of calcium, probably by increasing the complexation of calcium. Drugs that inhibit mPT or indirectly prevent mPT by enhancing the mitochondrial complexation of calcium and thereby their resistance to calcium overload may therefore prove to be successful strategies in limiting accidental cell death in the CNS

On stock return prediction with LSTM networks

Artificial neural networks are, again, on the rise. The decreasing costs of computing power and the availability of big data together with advancements of neural network theory have made this possible. In this thesis, LSTM (long short-term memory) recurrent neural networks are used in order to perform financial time series forecasting on return data of three stock indices. The indices are S&P 500 in the US, Bovespa 50 in Brazil and OMX 30 in Sweden. The results show that the outputs of the LSTM networks are very similar to those of a conventional time series model, namely an ARMA(1,1)-GJRGARCH(1,1), when a regression approach is taken. However, they outperform the time series model with regards to direction of change classification. The thesis shows significant results for direction of change classification for the small Swedish market, and insignificant results for the large US market and the emerging Brazilian market. When a trading strategy is implemented based on the direction of change, a deep LSTM network vastly outperforms the time series model

Feedforward neural networks with ReLU activation functions are linear splines

In this thesis the approximation properties of feedforward articial neural networks with one hidden layer and ReLU activation functions are examined. It is shown that functions of these kind are linear splines and the number of spline knots depend on the number of nodes in the network. In fact an upper bound can be derived for the number of knots. Furthermore, the positioning of the knots depend on the optimization of the adjustable parameters of the network. A numerical example is given where the network models are compared to linear interpolating splines with equidistant positioned knots

Respiratory uncoupling by increased H+ or K+ flux is beneficial for heart mitochondrial turnover of reactive oxygen species but not for permeability transition

Background: Ischemic preconditioning has been proposed to involve changes in mitochondrial H+ and K+ fluxes, in particular through activation of uncoupling proteins and ATP-sensitive K+ channels (MitoK(ATP)). The objectives of the present study were to explore how increased H+ and K+ fluxes influence heart mitochondrial physiology with regard to production and scavenging of reactive oxygen species (ROS), volume changes and resistance to calcium-induced mitochondrial permeability transition (mPT). Results: Isolated rat heart mitochondria were exposed to a wide concentration range of the protonophore CCCP or the potassium ionophore valinomycin to induce increased H+ and K+ conductance, respectively. Simultaneous monitoring of mitochondrial respiration and calcium retention capacity (CRC) demonstrated that the relative increase in respiration caused by valinomycin or CCCP correlated with a decrease in CRC, and that no level of respiratory uncoupling was associated with enhanced resistance to mPT. Mitochondria suspended in hyperosmolar buffer demonstrated a dose-dependent reduction in CRC with increasing osmolarity. However, mitochondria in hypoosmolar buffer to increase matrix volume did not display increased CRC. ROS generation was reduced by both K+- and H+-mediated respiratory uncoupling. The ability of heart mitochondria to detoxify H2O2 was substantially greater than the production rate. The H2O2 detoxification was dependent on respiratory substrates and was dramatically decreased following calcium-induced mPT, but was unaffected by uncoupling via increased K+ and H+ conductance. Conclusion: It is concluded that respiratory uncoupling is not directly beneficial to rat heart mitochondrial resistance to calcium overload irrespective of whether H+ or K+ conductance is increased. The negative effects of respiratory uncoupling thus probably outweigh the reduction in ROS generation and a potential positive effect by increased matrix volume, resulting in a net sensitization of heart mitochondria to mPT activation

Arbetsmaskiners bidrag till luftföroreningar i tätorter

The Swedish government has decided an action plan against particulate matter (PM10) within the county of Stockholm. Among other thing, the action plan stipulate that measures shall be taken in order to increase the knowledge about emissions of PM10 from non-road mobile machinery and their contribution to the air quality within densely populated areas. Non-road mobile machinery are characterised as mobile machinery not intended for the use of passenger- or goods-transport on the road, and equipped with an internal combustion engine as specified in directive 97/68/EC and directive 2000/25/EC, i.e. agricultural and forestry tractors and construction equipment such as wheel loaders, excavators, articulated haulers and mobile cranes. The purpose of this project, which was financed by the Swedish national road administration, was to update and summarise the current knowledge concerning fuel consumption and emissions from non-road mobile machinery and their contribution to the air quality in densely populated areas. A more specific aim of the project was to estimate the occurrence and age distribution and annual work hours of non-road mobile machinery within densely populated areas. Furthermore, annual fuel consumption and emissions amounts were also derived. Usually a single emission factor for each pollutant has been used when estimating emissions from the entire non-road mobile machinery sector, which has resulted in fairly uncertain results. Previous research has shown that it is not possible to develop one single set of emission factors that gives representative results for all types of non-road mobile machinery and operations (Hansson et al., 2001; Starr et al., 1999; Ullman et al., 1999). The latest research within the EMMA-projects in Sweden about the presence, use and emissions from non-road mobile machinery has resulted in better knowledge and data concerning emissions from non-road mobile machinery. Within the present project, emissions from non-road mobile machinery in two densely populated areas or population centres with different sizes have been studied. One large population centre represented by the city of Stockholm and one small represented by the town of Ljungby. The calculation of fuel consumption and emissions from non-road mobile machinery within the city of Stockholm has been conducted in accordance with the advanced approach presented by the emission inventory guidebook from the European Environement Agency (EEA, 2005). However, the methodology has been modified in order to thoroughly represent the actual assembly of non-road mobile machinery including the work performed by those machines annually. The same model that was used to derive fuel consumption has been employed for emissions as well. Compared with using average information, more reliable data were obtained through describing the number of machines, annual hour, engine power, load factor, specific fuel consumption and emissions amounts for each type of non-road mobile machinery and model year. All data were stored and used in different matrices, one for each variable. In total 31 different types of machines were defined for which data were collected for all model years from 1982 to 2006. Extensive inventories of non-road mobile machinery were carried out for both the city of Stockholm and Ljungby. For Stockholm the inventory contained both number of units and annual work hour as function of the age of the machinery. Reliable data could be obtained through the Swedish Machinery Testing Institute’s accredited inspection database in combination with statistics over both annual sale returns and registered machinery from the national vehicle database. The results from the inventory showed that about 2 800 non-road mobile machinery with both varying age and annual work hours operated within the city of Stockholm. In the city of Ljungby, less than 100 non-road mobile machinery were estimated to operate, thus called for an alternative method for the inventory. Based on data from local contractors that operated in the city of Ljungby, annual work hour for different types of non-road mobile machinery were collected. The result showed that about 48 000 hours of work with non-road mobile machinery were carried out within the city of Ljungby annually. Moreover, the majority of the work were performed with wheel loaders and different types of excavators. In table S1 annual emission- and fuel consumption amounts from the non-road mobile machinery sector in the cities of Stockholm and Ljungby year 2006 are shown

Intraluminal aortic manipulation by means of intra-aortic filter, cannulation, and external clamp maneuvers evaluated versus dislodged embolic material

ObjectivesAortic atherosclerosis is an important risk factor for cerebrovascular accidents in cardiac surgery. An intra-aortic filter might reduce this risk. We aimed to analyze the risks for emboli associated with intraluminal aortic manipulation and intra-aortic filter handling in relation to cannulation and external clamp maneuvers.MethodsA model was designed with a cadaver aorta and retrograde perfusion (n = 16). A crossclamp was positioned on the ascending aorta and repeatedly opened under pressure to collect aliquots with dislodged particles. Cannulation was performed after 10 clamp maneuvers, followed by positioning and removing the intra-aortic filter, with each step followed by a washout sequence to collect perfusate. The removed filter was also analyzed. Evaluation was by means of digital image analysis, with differentiation of particles into different spectra.ResultsIntra-aortic filter manipulation produced a significant washout of embolic particles; in particular, this was seen for the macroscopic cellular spectrum (P = .006 and P = .002 for filter insertion and removal, respectively). Particles were also found to be collected by the filter (P = .004). In addition, cannulation and aortic crossclamp manipulation generated a notable number of particles (P = .001 and P = .013, respectively).ConclusionsThe intra-aortic filter collects material during aortic manipulation. However, intraluminal aortic manipulation from filter handling can also dislodge particles, possibly related to shedding of intimal debris. This is in addition to substantial amounts of particles that are generated by aortic cannulation and aortic crossclamping

Differential Proteome Analysis of the Preeclamptic Placenta Using Optimized Protein Extraction

The human placenta is a difficult tissue to work with using proteomic technology since it contains large amounts of lipids and glycogen. Both lipids and glycogen are known to interfere with the first step in the two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), the isoelectric focusing. In order to gain the best possible protein separation on 2D-PAGE, an optimized sample preparation protocol for placental proteins was developed. Two different buffers, urea/CHAPS and Hepes, were used for solubilization in combination with six different precipitation methods. The removal of glycogen from the samples by centrifugation was crucial for the final proteome maps. Solubilization with urea/CHAPS in combination with dichloromethane/methanol or acidified acetone proved to be the best precipitation procedures. When applied to clinical placenta samples apolipoprotein A1 was found to be accumulated in the preeclamptic placenta, where it may either have a nutritional effect or act as a modifier of signal transduction

On a Constitutive Material Model to Capture Time Dependent Behaviour of Cortical Bone

It is commonly known that cortical bone exhibits viscoelastic-viscoplastic behavior which affects the biomechanical response when an implant is subjected to an external load. In addition, long term effects such as creep, relaxation and remodeling affect the success of the implant over time. Constitutive material models are commonly derived from data obtained in\ua0in vitro\ua0experiments. However during function, remodeling of bone greatly affects the bone material over time. Hence it is essential to include long term\ua0in vivo\ua0effects in a constitutive model of bone. This paper proposes a constitutive material model for cortical bone incorporating viscoelasticity, viscoplasticity, creep and remodeling to predict stress-strain at various strain rates as well as the behavior of bone over time\ua0in vivo. The rheological model and its parameters explain the behavior of bone subjected to longitudinal loading. By a proper set of model parameters, for a specific cortical bone, the present model can be used for prediction of the behavior of this bone under specific loading conditions. In addition simulation with the proposed model demonstrates excellent agreement to\ua0in vitro\ua0and\ua0in vivo\ua0experimental results in the literature

Hemoglobin induces inflammation after preterm intraventricular hemorrhage by methemoglobin formation.

Cerebral intraventricular hemorrhage (IVH) is a major cause of severe neurodevelopmental impairment in preterm infants. To date, no therapy is available that prevents infants from developing serious neurological disability following IVH. Thus, to develop treatment strategies for IVH, it is essential to characterize the initial sequence of molecular events that leads to brain damage. In this study, we investigated extracellular hemoglobin (Hb) as a causal initiator of inflammation in preterm IVH

Model optimization for autotuners in industrial control systems

Automatic tuning of PID controllers using relay feedback experiments has received attention on and off since it was first proposed and industrially implemented in a control system in the 1980s. While optimal experiment design and modern system identification easily outperform the original automatic tuner, they rely on computational resources that are not always available in industrial control systems. Here we present a combination of experiment and subsequent output-error identification of continuoustime first-order time-delayed (FOTD) system models, that requires very little in terms of computations and memory. The method has been extensively evaluated in simulation, and a prototype has been implemented for the ABB AC 800M controller family