Phosphoproteomics-Based Modeling Defines the Regulatory Mechanism Underlying Aberrant EGFR Signaling

BACKGROUND: Mutation of the epidermal growth factor receptor (EGFR) results in a discordant cell signaling, leading to the development of various diseases. However, the mechanism underlying the alteration of downstream signaling due to such mutation has not yet been completely understood at the system level. Here, we report a phosphoproteomics-based methodology for characterizing the regulatory mechanism underlying aberrant EGFR signaling using computational network modeling. METHODOLOGY/PRINCIPAL FINDINGS: Our phosphoproteomic analysis of the mutation at tyrosine 992 (Y992), one of the multifunctional docking sites of EGFR, revealed network-wide effects of the mutation on EGF signaling in a time-resolved manner. Computational modeling based on the temporal activation profiles enabled us to not only rediscover already-known protein interactions with Y992 and internalization property of mutated EGFR but also further gain model-driven insights into the effect of cellular content and the regulation of EGFR degradation. Our kinetic model also suggested critical reactions facilitating the reconstruction of the diverse effects of the mutation on phosphoproteome dynamics. CONCLUSIONS/SIGNIFICANCE: Our integrative approach provided a mechanistic description of the disorders of mutated EGFR signaling networks, which could facilitate the development of a systematic strategy toward controlling disease-related cell signaling

A Neutrophil Phenotype Model for Extracorporeal Treatment of Sepsis

Neutrophils play a central role in eliminating bacterial pathogens, but may also contribute to end-organ damage in sepsis. Interleukin-8 (IL-8), a key modulator of neutrophil function, signals through neutrophil specific surface receptors CXCR-1 and CXCR-2. In this study a mechanistic computational model was used to evaluate and deploy an extracorporeal sepsis treatment which modulates CXCR-1/2 levels. First, a simplified mechanistic computational model of IL-8 mediated activation of CXCR-1/2 receptors was developed, containing 16 ODEs and 43 parameters. Receptor level dynamics and systemic parameters were coupled with multiple neutrophil phenotypes to generate dynamic populations of activated neutrophils which reduce pathogen load, and/or primed neutrophils which cause adverse tissue damage when misdirected. The mathematical model was calibrated using experimental data from baboons administered a two-hour infusion of E coli and followed for a maximum of 28 days. Ensembles of parameters were generated using a Bayesian parallel tempering approach to produce model fits that could recreate experimental outcomes. Stepwise logistic regression identified seven model parameters as key determinants of mortality. Sensitivity analysis showed that parameters controlling the level of killer cell neutrophils affected the overall systemic damage of individuals. To evaluate rescue strategies and provide probabilistic predictions of their impact on mortality, time of onset, duration, and capture efficacy of an extracorporeal device that modulated neutrophil phenotype were explored. Our findings suggest that interventions aiming to modulate phenotypic composition are time sensitive. When introduced between 3–6 hours of infection for a 72 hour duration, the survivor population increased from 31% to 40–80%. Treatment efficacy quickly diminishes if not introduced within 15 hours of infection. Significant harm is possible with treatment durations ranging from 5–24 hours, which may reduce survival to 13%. In severe sepsis, an extracorporeal treatment which modulates CXCR-1/2 levels has therapeutic potential, but also potential for harm. Further development of the computational model will help guide optimal device development and determine which patient populations should be targeted by treatment

Cell-signalling dynamics in time and space

The specificity of cellular responses to receptor stimulation is encoded by the spatial and temporal dynamics of downstream signalling networks. Computational models provide insights into the intricate relationships between stimuli and responses and reveal mechanisms that enable networks to amplify signals, reduce noise and generate discontinuous bistable dynamics or oscillations. These temporal dynamics are coupled to precipitous spatial gradients of signalling activities, which guide pivotal intracellular processes, but also necessitate mechanisms to facilitate signal propagation across a cell

Performance investigations of frequency agile enabled TelosB testbed in Home area network

Home area network (HAN) consists of several wireless technologies and appliances that normally operate in the ISM 2.4-GHz band. This spectrum sharing environment can introduce interference problems and prevent peaceful coexistence especially for low power radio devices. Therefore, it is significant that these radio devices are spectrum agile as to avoid harmful interference and utilize the spectrum reliably. In this paper, the performance of a ZigBee Frequency Agile (FA) technique implemented on TelosB testbed is studied experimentally. The measurement results show that this technique can effectively overcome the interference caused by the Wi-Fi-based devices by changing the operating frequency of the ZigBee's FA-enabled testbed to the channel with the least interference level. In addition, the testbed with FA achieves throughput improvement by about 86%, reduces delay by 73% and enhances transmission energy efficiency by 64% as compared to the testbed without FA. Consequently, this proves that the FA mechanism can guarantee a seamless communication as well as incurring low transmission cost

Infection control bundles in intensive care: an international cross-sectional survey in low- and middle-income countries

Background: In low- and middle-income countries (LMICs), the burden of healthcare-associated infections (HCAIs) is not known due to a lack of national surveillance systems, standardized infection definitions, and paucity of infection prevention and control (IPC) organizations and legal infrastructure

Acute hepatitis B despite a previous high titer of anti-HBs

Loss of HBsAg and development of surface and core antibodies represent clinical cure. However, recent evidence suggests that hepatitis B virus (HBV) persists in a latent state even in those with mounted protective antibodies. After significant immunosuppression, anti-HBs may decrease and HBsAg may reappear (reverse seroconversion). Reverse seroconversion of HBV has been observed in association with hematopoietic stem cell transplantation, renal transplantation, intensive chemotherapy, human immunodeficiency infection, or rituximab usage