Integrated Multiscale Modeling of the Nervous System: Predicting Changes in Hippocampal Network Activity by a Positive AMPA Receptor Modulator

One of the fundamental characteristics of the brain is its hierarchical organization. Scales in both space and time that must be considered when integrating across hierarchies of the nervous system are sufficiently great as to have impeded the development of routine multilevel modeling methodologies. Complex molecular interactions at the level of receptors and channels regulate activity at the level of neurons; interactions between multiple populations of neurons ultimately give rise to complex neural systems function and behavior. This spatial complexity takes place in the context of a composite temporal integration of multiple, different events unfolding at the millisecond, second, minute, hour, and longer time scales. In this study, we present a multiscale modeling methodology that integrates synaptic models into single neuron, and multineuron, network models. We have applied this approach to the specific problem of how changes at the level of kinetic parameters of a receptor-channel model are translated into changes in the temporal firing pattern of a single neuron, and ultimately, changes in the spatiotemporal activity of a network of neurons. These results demonstrate how this powerful methodology can be applied to understand the effects of a given local process within multiple hierarchical levels of the nervous system

Simulation of Postsynaptic Glutamate Receptors Reveals Critical Features of Glutamatergic Transmission

Activation of several subtypes of glutamate receptors contributes to changes in postsynaptic calcium concentration at hippocampal synapses, resulting in various types of changes in synaptic strength. Thus, while activation of NMDA receptors has been shown to be critical for long-term potentiation (LTP) and long term depression (LTD) of synaptic transmission, activation of metabotropic glutamate receptors (mGluRs) has been linked to either LTP or LTD. While it is generally admitted that dynamic changes in postsynaptic calcium concentration represent the critical elements to determine the direction and amplitude of the changes in synaptic strength, it has been difficult to quantitatively estimate the relative contribution of the different types of glutamate receptors to these changes under different experimental conditions. Here we present a detailed model of a postsynaptic glutamatergic synapse that incorporates ionotropic and mGluR type I receptors, and we use this model to determine the role of the different receptors to the dynamics of postsynaptic calcium with different patterns of presynaptic activation. Our modeling framework includes glutamate vesicular release and diffusion in the cleft and a glutamate transporter that modulates extracellular glutamate concentration. Our results indicate that the contribution of mGluRs to changes in postsynaptic calcium concentration is minimal under basal stimulation conditions and becomes apparent only at high frequency of stimulation. Furthermore, the location of mGluRs in the postsynaptic membrane is also a critical factor, as activation of distant receptors contributes significantly less to calcium dynamics than more centrally located ones. These results confirm the important role of glutamate transporters and of the localization of mGluRs in postsynaptic sites in their signaling properties, and further strengthen the notion that mGluR activation significantly contributes to postsynaptic calcium dynamics only following high-frequency stimulation. They also provide a new tool to analyze the interactions between metabotropic and ionotropic glutamate receptors

Combined pancreatic islets-lung transplantation in cystic fibrosis-related diabetes: case reports

We report two cases of percutaneous portal embolization of pancreatic islets performed after double lung transplantation in cystic fibrosis (CF) patients using the pancreas of the same donor. CASE 1: A 19-year-old man with CF had insulin-dependent diabetes, which was poorly controlled despite an external insulin pump (96 IU/d): HbA(1c) = 9.8% and 1 to 3 hypoglycemic events per day. On October 29, 2007, he received a double lung graft because of chronic respiratory failure. For days after lung transplantation, 149,000 cultured IEQ (Islet EQuivalent) were injected by percutaneous intraportal infusion under local anesthesia. Immunosuppression consisted of steroids, cyclosporine, and azathioprine. Two years later, the forced expiratory volume (FEV) was 83%; C peptide level reached 1.4 mug/L, and the diabetes was satisfactorily controlled with an HbA(1c) of 7.5% and a decrease in insulin requirements to 30 U/d in the absence of hypoglycemic events. CASE 2: On July 10, 2006, a 32-year-old man with CF-related diabetes received a double lung graft because of chronic respiratory failure. Under multiple insulin injections, the HbA(1c) was 9.6% with numerous hypoglycemic events. On March 11, 2008, he again received a double lung graft because of persistent humoral rejection. Despite severe bleeding during the postoperative course, 234,000 IEQ were injected via the portal vein one week after lung transplantation. Immunosuppression consisted of steroids, tacrolimus, and mycophenolate mofetil. Eighteen months after the combined graft, the FEV was 52%; the plasma C-peptide reached 0.79 mug/L, the HbA(1c), 6% and the insulin requirements decreased to 55 U/d in the absence of hypoglycemic events. CONCLUSION: Combined lung-islet transplantation for patients with CF-related diabetes improved pulmonary and metabolic function

Modeling and simulation of organophosphate-induced neurotoxicity: Prediction and validation by experimental studies

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Combined pancreatic islet-lung transplantation: a novel approach to the treatment of end-stage cystic fibrosis

Patients with end-stage cystic fibrosis (CF) and severe CF-related diabetes (CFRD) may benefit from combined lung-pancreatic islet transplantation. In the present study, we report the long-term follow-up of four end-stage CF patients treated with combined bilateral lung and pancreatic islet transplantation from the same donor. All patients were C-peptide negative (0.5 microg/L). At 6 months after transplantation, one patient showed multiple episodes of acute lung transplant rejection and a progressive decline in pancreatic islet cell function. Three out of four patients experienced an improved control of glucose levels with a HbA1c of 5.2%, 7% and 6% respectively at 1.5, 2 and 15 years follow-up. Compared with the pretransplant period, there was a 50% reduction in mean daily insulin needs. Pulmonary function remained satisfactory in all patients. In conclusion, our cases series shows that combined bilateral lung and pancreatic islet transplantation may be a viable therapeutic option for patients with end-stage CF and CFRD

Orienting the Demixion of a Diblock-copolymer Using 193 nm Interferometric Lithography for the Controlled Deposition of Nanoparticles

DUV interferometric lithography and diblock copolymer self-organization have successfully been combined to provide a simple and highly collective nanopatterning technique enabling the organization of nanoparticles over several orders of magnitude, from nanometre to millimetre. The nanostructural changes at the surface of the polymer film after thermal annealing have been monitored by AFM and the process parameters optimized for obtaining a long-range organization of the lamellar domains. In particular, the impact of the annealing conditions and geometric parameters of the substrate patterns have been investigated. The nanopatterns resulting from the lamellar demixion of (PS-b-MMA) were used for a controlled deposition of nanoparticles. The affinity of the hydrophobic particles for the PS block was demonstrated, opening new doors towards the preparation of high-density arrays of nanoparticles with potential applications in data storage

Magnetic Properties of Gold Nanoparticles: A Room-Temperature Quantum Effect:

Persistent currents: The magnetism of Au nanoparticles might result from persistent currents. Limited portions of a given sample may even support self‐sustained currents, thus exhibiting remnant magnetization and hysteresis. Observing such a quantum effect at room temperature with user‐friendly samples opens unforeseen possibilities

Efficacy and safety of selective internal radiotherapy with yttrium-90 resin microspheres compared with sorafenib in locally advanced and inoperable hepatocellular carcinoma (SARAH): an open-label randomised controlled phase 3 trial

International audienceBackgroundSorafenib is the recommended treatment for patients with advanced hepatocellular carcinoma. We aimed to compare the efficacy and safety of sorafenib to that of selective internal radiotherapy (SIRT) with yttrium-90 (90Y) resin microspheres in patients with hepatocellular carcinoma.MethodsSARAH was a multicentre, open-label, randomised, controlled, investigator-initiated, phase 3 trial done at 25 centres specialising in liver diseases in France. Patients were eligible if they were aged at least 18 years with a life expectancy greater than 3 months, had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, Child-Pugh liver function class A or B score of 7 or lower, and locally advanced hepatocellular carcinoma (Barcelona Clinic Liver Cancer [BCLC] stage C), or new hepatocellular carcinoma not eligible for surgical resection, liver transplantation, or thermal ablation after a previously cured hepatocellular carcinoma (cured by surgery or thermoablative therapy), or hepatocellular carcinoma with two unsuccessful rounds of transarterial chemoembolisation. Patients were randomly assigned (1:1) by a permutated block method with block sizes two and four to receive continuous oral sorafenib (400 mg twice daily) or SIRT with 90Y-loaded resin microspheres 2–5 weeks after randomisation. Patients were stratified according to randomising centre, ECOG performance status, previous transarterial chemoembolisation, and presence of macroscopic vascular invasion. The primary endpoint was overall survival. Analyses were done on the intention-to-treat population; safety was assessed in all patients who received at least one dose of sorafenib or underwent at least one of the SIRT work-up exams. This study has been completed and the final results are reported here. The trial is registered with ClinicalTrials.gov, number NCT01482442.FindingsBetween Dec 5, 2011, and March 12, 2015, 467 patients were randomly assigned; after eight patients withdrew consent, 237 were assigned to SIRT and 222 to sorafenib. In the SIRT group, 53 (22%) of 237 patients did not receive SIRT; 26 (49%) of these 53 patients were treated with sorafenib. Median follow-up was 27·9 months (IQR 21·9–33·6) in the SIRT group and 28·1 months (20·0–35·3) in the sorafenib group. Median overall survival was 8·0 months (95% CI 6·7–9·9) in the SIRT group versus 9·9 months (8·7–11·4) in the sorafenib group (hazard ratio 1·15 [95% CI 0·94–1·41] for SIRT vs sorafenib; p=0·18). In the safety population, at least one serious adverse event was reported in 174 (77%) of 226 patients in the SIRT group and in 176 (82%) of 216 in the sorafenib group. The most frequent grade 3 or worse treatment-related adverse events were fatigue (20 [9%] vs 41 [19%]), liver dysfunction (25 [11%] vs 27 [13%]), increased laboratory liver values (20 [9%] vs 16 [7%]), haematological abnormalities (23 [10%] vs 30 [14%]), diarrhoea (three [1%] vs 30 [14%]), abdominal pain (six [3%] vs 14 [6%]), increased creatinine (four [2%] vs 12 [6%]), and hand-foot skin reaction (one [<1%] vs 12 [6%]). 19 deaths in the SIRT group and 12 in the sorafenib group were deemed to be treatment related.InterpretationIn patients with locally advanced or intermediate-stage hepatocellular carcinoma after unsuccessful transarterial chemoembolisation, overall survival did not significantly differ between the two groups. Quality of life and tolerance might help when choosing between the two treatments.FundingSirtex Medical Inc