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Calmodulin-dependent kinase II (CaMKII) has long been known to play an important role in learning and memory as well as long term potentiation (LTP). More recently it has been suggested that it might be involved in the time averaging of synaptic signals, which can then lead to the high precision of information stored at a single synapse. However, the role of the scaffolding molecule, neurogranin (Ng), in governing the dynamics of CaMKII is not yet fully understood. In this work, we adopt a rule-based modeling approach through the Monte Carlo method to study the effect of Ca2+ signals on the dynamics of CaMKII phosphorylation in the postsynaptic density (PSD). Calcium surges are observed in synaptic spines during an EPSP and back-propagating action potential due to the opening of NMDA receptors and voltage dependent calcium channels. Using agent-based models, we computationally investigate the dynamics of phosphorylation of CaMKII monomers and dodecameric holoenzymes. The scaffolding molecule, Ng, when present in significant concentration, limits the availability of free calmodulin (CaM), the protein which activates CaMKII in the presence of calcium. We show that Ng plays an important modulatory role in CaMKII phosphorylation following a surge of high calcium concentration. We find a non-intuitive dependence of this effect on CaM concentration that results from the different affinities of CaM for CaMKII depending on the number of calcium ions bound to the former. It has been shown previously that in the absence of phosphatase, CaMKII monomers integrate over Ca2+ signals of certain frequencies through autophosphorylation (Pepke et al, Plos Comp. Bio., 2010). We also study the effect of multiple calcium spikes on CaMKII holoenzyme autophosphorylation, and show that in the presence of phosphatase, CaMKII behaves as a leaky integrator of calcium signals, a result that has been recently observed in vivo. Our models predict that the parameters of this leaky integrator are

Calmodulin-dependent kinase II (CaMKII) has long been known to play an important role in learning and memory as well as long term potentiation (LTP). More recently it has been suggested that it might be involved in the time averaging of synaptic signals, which can then lead to the high precision of information stored at a single synapse. However, the role of the scaffolding molecule, neurogranin (Ng), in governing the dynamics of CaMKII is not yet fully understood. In this work, we adopt a rule-based modeling approach through the Monte Carlo method to study the effect of Ca2+ signals on the dynamics of CaMKII phosphorylation in the postsynaptic density (PSD). Calcium surges are observed in synaptic spines during an EPSP and back-propagating action potential due to the opening of NMDA receptors and voltage dependent calcium channels. Using agent-based models, we computationally investigate the dynamics of phosphorylation of CaMKII monomers and dodecameric holoenzymes. The scaffolding molecule, Ng, when present in significant concentration, limits the availability of free calmodulin (CaM), the protein which activates CaMKII in the presence of calcium. We show that Ng plays an important modulatory role in CaMKII phosphorylation following a surge of high calcium concentration. We find a non-intuitive dependence of this effect on CaM concentration that results from the different affinities of CaM for CaMKII depending on the number of calcium ions bound to the former. It has been shown previously that in the absence of phosphatase, CaMKII monomers integrate over Ca2+ signals of certain frequencies through autophosphorylation (Pepke et al, Plos Comp. Bio., 2010). We also study the effect of multiple calcium spikes on CaMKII holoenzyme autophosphorylation, and show that in the presence of phosphatase, CaMKII behaves as a leaky integrator of calcium signals, a result that has been recently observed in vivo. Our models predict that the parameters of this leaky integrator are

Background: Physicians' adherence to guideline-recommended therapy is associated with short-term clinical outcomes in heart failure (HF) with reduced ejection fraction (HFrEF). However, its impact on longer-term outcomes is poorly documented. Here, we present results from the 18-month follow-up of the QUALIFY registry. Methods and results: Data at 18 months were available for 6118 ambulatory HFrEF patients from this international prospective observational survey. Adherence was measured as a continuous variable, ranging from 0 to 1, and was assessed for five classes of recommended HF medications and dosages. Most deaths were cardiovascular (CV) (228/394) and HF-related (191/394) and the same was true for unplanned hospitalizations (1175 CV and 861 HF-related hospitalizations, out of a total of 1541). According to univariable analysis, CV and HF deaths were significantly associated with physician adherence to guidelines. In multivariable analysis, HF death was associated with adherence level [subdistribution hazard ratio (SHR) 0.93, 95% confidence interval (CI) 0.87–0.99 per 0.1 unit adherence level increase; P = 0.034] as was composite of HF hospitalization or CV death (SHR 0.97, 95% CI 0.94–0.99 per 0.1 unit adherence level increase; P = 0.043), whereas unplanned all-cause, CV or HF hospitalizations were not (all-cause: SHR 0.99, 95% CI 0.9–1.02; CV: SHR 0.98, 95% CI 0.96–1.01; and HF: SHR 0.99, 95% CI 0.96–1.02 per 0.1 unit change in adherence score; P = 0.52, P = 0.2, and P = 0.4, respectively). Conclusion: These results suggest that physicians' adherence to guideline-recommended HF therapies is associated with improved outcomes in HFrEF. Practical strategies should be established to improve physicians' adherence to guidelines. © 2019 The Authors. European Journal of Heart Failure © 2019 European Society of Cardiology

ATP-powered viral packaging motors are among the most powerful biomotors known. Motor subunits arranged in a ring repeatedly grip and translocate the DNA to package viral genomes into capsids. Here, we use single DNA manipulation and rapid solution exchange to quantify how nucleotide binding regulates interactions between the bacteriophage T4 motor and DNA substrate. With no nucleotides, there is virtually no gripping and rapid slipping occurs with only minimal friction resisting. In contrast, binding of an ATP analog engages nearly continuous gripping. Occasional slips occur due to dissociation of the analog from a gripping motor subunit, or force-induced rupture of grip, but multiple other analog-bound subunits exert high friction that limits slipping. ADP induces comparably infrequent gripping and variable friction. Independent of nucleotides, slipping arrests when the end of the DNA is about to exit the capsid. This end-clamp mechanism increases the efficiency of packaging by making it essentially irreversible.

ATP-powered viral packaging motors are among the most powerful biomotors known. Motor subunits arranged in a ring repeatedly grip and translocate the DNA to package viral genomes into capsids. Here, we use single DNA manipulation and rapid solution exchange to quantify how nucleotide binding regulates interactions between the bacteriophage T4 motor and DNA substrate. With no nucleotides, there is virtually no gripping and rapid slipping occurs with only minimal friction resisting. In contrast, binding of an ATP analog engages nearly continuous gripping. Occasional slips occur due to dissociation of the analog from a gripping motor subunit, or force-induced rupture of grip, but multiple other analog-bound subunits exert high friction that limits slipping. ADP induces comparably infrequent gripping and variable friction. Independent of nucleotides, slipping arrests when the end of the DNA is about to exit the capsid. This end-clamp mechanism increases the efficiency of packaging by making it essentially irreversible.

The viral DNA packaging motors are among the most powerful biological machines known, and their mechanisms have been of interest for decades. The work presented in this dissertation has been dedicated to studying these mechanisms on the example of the T4 and Lambda bacteriophages, which are well known model organisms.Custom-built optical tweezers were utilized for real time observations of single DNA molecule packaging. A force-feedback loop allowed us to study the DNA translocation fueled by ATP hydrolysis under different conditions.The regulation of the motors grip on the DNA by the nucleotide state was investigated through a novel technique, and the interaction of the motor subunits with the DNA was shown to depend on the state of the ATP-binding pockets. This finding brings us closer to understanding the level of coordination between the subunits during translocation. The fact that the motors grip on the DNA depends on the nucleotide state also allows to judge about the state of the ATP-binding pocket based on the packaging dynamics. A novel mechanism of the clamping of the DNA by the packaging complex to prevent dissociation was identified in the course of these experiments.The role of the putative conserved Walker A and Walker B ATP binding motifs were examined through mutagenesis studies. An extensive study of 23 different mutants in single-molecule experiments was conducted, and it was concluded that these regions are indeed involved in ATP-binding, but we also identified residues from this region that are important for ATP-alignment, catalysis of hydrolysis, and mechanochemical coupling. In addition measurements on the mutation of the glutamate residue E179 directly downstream of Walker B were performed, and it confirmed that this residue catalyzes the hydrolysis.A conserved Loop-Helix-Loop region previously studied in this lab, and proposed to play a regulatory role in translocation velocity was also studied. 8 different mutants were probed in the single-m

The viral DNA packaging motors are among the most powerful biological machines known, and their mechanisms have been of interest for decades. The work presented in this dissertation has been dedicated to studying these mechanisms on the example of the T4 and Lambda bacteriophages, which are well known model organisms.Custom-built optical tweezers were utilized for real time observations of single DNA molecule packaging. A force-feedback loop allowed us to study the DNA translocation fueled by ATP hydrolysis under different conditions.The regulation of the motors grip on the DNA by the nucleotide state was investigated through a novel technique, and the interaction of the motor subunits with the DNA was shown to depend on the state of the ATP-binding pockets. This finding brings us closer to understanding the level of coordination between the subunits during translocation. The fact that the motors grip on the DNA depends on the nucleotide state also allows to judge about the state of the ATP-binding pocket based on the packaging dynamics. A novel mechanism of the clamping of the DNA by the packaging complex to prevent dissociation was identified in the course of these experiments.The role of the putative conserved Walker A and Walker B ATP binding motifs were examined through mutagenesis studies. An extensive study of 23 different mutants in single-molecule experiments was conducted, and it was concluded that these regions are indeed involved in ATP-binding, but we also identified residues from this region that are important for ATP-alignment, catalysis of hydrolysis, and mechanochemical coupling. In addition measurements on the mutation of the glutamate residue E179 directly downstream of Walker B were performed, and it confirmed that this residue catalyzes the hydrolysis.A conserved Loop-Helix-Loop region previously studied in this lab, and proposed to play a regulatory role in translocation velocity was also studied. 8 different mutants were probed in the single-m

This research investigated how social status impacts economic behavior. First experiment inspired by Range-Frequency Theory tests whether the position between top and bottom members of a comparison group affects social risk-attitudes. The study found no such impact. Second experiment examined the role of internal status hierarchy within small groups during collective risky decisions. Hierarchy does not lead to faster collective decisions as we hypothesise. On the contrary, low-status males resist more during collective decisions. Third experiment investigated the impact of two-dimensional social status on ultimatum bargaining. The study found no evidence of conflict when subjects hold opposite set of statuses on two different hierarchies.

During the assembly of many viruses, a powerful ATP-driven motor translocates DNA into a preformed procapsid. A Walker-A "P-loop" motif is proposed to coordinate ATP binding and hydrolysis with DNA translocation. We use genetic, biochemical, and biophysical techniques to survey the roles of P-loop residues in bacteriophage lambda motor function. We identify 55 point mutations that reduce virus yield to below detectable levels in a highly sensitive genetic complementation assay and 33 that cause varying reductions in yield. Most changes in the predicted conserved residues K76, R79, G81, and S83 produce no detectable yield. Biochemical analyses show that R79A and S83A mutant proteins fold, assemble, and display genome maturation activity similar to wild-type (WT) but exhibit little ATPase or DNA packaging activity. Kinetic DNA cleavage and ATPase measurements implicate R79 in motor ring assembly on DNA, supporting recent structural models that locate the P-loop at the interface between motor subunits. Single-molecule measurements detect no translocation for K76A and K76R, while G81A and S83A exhibit strong impairments, consistent with their predicted roles in ATP binding. We identify eight residue changes spanning A78-K84 that yield impaired translocation phenotypes and show that Walker-A residues play important roles in determining motor velocity, pausing, and processivity. The efficiency of initiation of packaging correlates strongly with motor velocity. Frequent pausing and slipping caused by changes A78V and R79K suggest that these residues are important for ATP alignment and coupling of ATP binding to DNA gripping. Our findings support recent structural models implicating the P-loop arginine in ATP hydrolysis and mechanochemical coupling.