The clinical and virological aspects of human influenza virus A (H5N1) infection in South Vietnam 2004-2005

Since the re-emergence of avian influenza A H5N1 virus in 2003 among poultry, the virus has reached endemic levels in Vietnam and continues to cause human infections. At present (9 February 2011), 119 infections have been reported, 59 of which were fatal. The cases in 2004 and 2005 accounted for 76% (90/119) of the total number of reported cases from Vietnam. This thesis retrospectively studied the clinical course of 16 cases (14%). The clinical features in most cases were typical for the human disease caused by the H5N1 virus. The prominent clinical signs and symptoms were those of a severe influenza syndrome with fever, cough, and shortness of breath. However, this thesis also shows that human H5N1 influenza may be associated with extrapulmonary disease, including gastrointestinal and eNS symptoms and multi-organ failure. The abnormalities on chest radiographs included extensive bilateral infiltration, lobar collapse, focal consolidation, and air bronchograms. The prominent laboratory factors were thrombocytopenia, neutropenia, lymphopenia, and increased levels of serum transaminases. Most patients (15/16) were treated with standard doses of the neuraminidase inhibitor oseltamivir. This drug has antiviral efficacy against H5N1 viruses and observational studies suggest that treatment with oseltamivir reduces mortality. Drug resistance may emerge during treatment and seems associated with antiviral and clinical failure. When testing for genotypic and phenotypic resistance, we detected 2 oseltamivir resistant H5N1 variants in two patients who failed to clear the virus and died from the infection. In contrast, four other patients who showed effective suppression of viral replication during treatment all survived. Molecular analysis of 13 H5N1 virus strains isolated from 13/16 patients showed that all viruses belonged to clade 1, genotype Z H5N1 viruses. The viruses retained the molecular characteristics of avian viruses. Some virus strains had mutations in the HA 1 gene that potentially affect receptor specificity, i.e. reduce recognition of 'avian-type' receptors, increase recognition of 'human-type' receptors, or both. A Glu-627-Lys substitution in the viral polymerase PB2, associated with adaptation and virulence of H5N 1 viruses in mammals, was observed in 5 of 8 isolates from fatal cases and in 3 of 4 isolates from patients who survived. However, no association between the presence of Lys-627 and clinical outcome was observed. However, in all except one of the isolates without the Glu-627-Lys substitution, an alternative change at position 701 (Asp to Asn) was observed which has also been associated with adaptation of avian viruses to replication in mammals. Data from this study also provided evidence for the selection of mutations in HA gene during infection, supporting the notion that continuing transmission of H5N1 virus from poultry to humans may provide a greater opportunity for the virus to adapt to humans. In addition, to support the diagnostic programme, I developed a molecular diagnostic assay that can detect both clade 1 (South-Vietnam, Cambodia, Thailand) and clade 2 (North Vietnam, Indonesia, Egypt) H5N1 virus variants. This molecular assay may be useful for diagnosis of H5 virus infections in regions where different genetic clades co-circulate

Multi-source in DF cooperative networks with the PSR protocol based full-duplex energy harvesting over a Rayleigh fading channel: performance analysis

Due to the tremendous energy consumption growth with ever-increasing connected devices, alternative wireless information and power transfer techniques are important not only for theoretical research but also for saving operational costs and for a sustainable growth of wireless communications. In this paper, we investigate the multi-source in decode-and-forward cooperative networks with the power splitting protocol based full-duplex energy harvesting relaying network over a Rayleigh fading channel. In this system model, the multi-source and the destination communicate with each other by both the direct link and an intermediate helping relay. First, we investigate source selection for the best system performance. Then, the closed-form expression of the outage probability and the symbol error ratio are derived. Finally, the Monte Carlo simulation is used for validating the analytical expressions in connection with all main possible system parameters. The research results show that the analytical and simulation results matched well with each other.Web of Science68327526

Power beacon-assisted energy harvesting in a half-duplex communication network under co-channel interference over a Rayleigh fading environment: Energy efficiency and outage probability analysis

In this time, energy efficiency (EE), measured in bits per Watt, has been considered as an important emerging metric in energy-constrained wireless communication networks because of their energy shortage. In this paper, we investigate power beacon assisted (PB) energy harvesting (EH) in half-duplex (HD) communication network under co-channel Interferer over Rayleigh fading environment. In this work, we investigate the model system with the time switching (TS) protocol. Firstly, the exact and asymptotic form expressions of the outage probability (OP) are analyzed and derived. Then the system EE is investigated and the influence of the primary system parameters on the system performance. Finally, we verify the correctness of the analytical expressions using Monte Carlo simulation. Finally, we can state that the simulation and analytical results are the same.Web of Science1213art. no. 257

Hybrid protocol for wireless EH network over weibull fading channel: performance analysis

In this paper, the hybrid TSR-PSR protocol for wireless energy harvesting (EH) relaying network over the Weibull fading channel is investigated. The system network is working in half-duplex (HD) mode. For evaluating the system performance, the closed-form and integral-form expressions of the outage probability (OP) are investigated and derived. After that, numerical results convinced that our derived analytical results are the same with the simulation results by using Monte Carlo simulation. This paper provides a novel recommendation for the wireless EH relaying network

Retinal degeneration in and in vivo electroretinography measurements of Smoky Joe Chickens

Inherited retinal degenerative diseases can affect various components of the retina leading to blindness. Five different mutant strains of chicken have been studied extensively as potential models for inherited retinal degeneration. The Smoky Joe (SJ) chicken is a sixth genetically blind strain of White Leghorns that shows various degrees of blindness at hatch and by 8 weeks post-hatch, have complete blindness for those that are homozygous. The objective of this study was to characterize the retinal degeneration in these birds by histology, both during embryonic and post-hatch development, and to the retinal function using electroretinograms (ERG). For both embryonic and post-hatch development, a significantly lower number of cells were found in the retina of blind birds compared to sighted (both p<0.0001). The significant contributor to cell number decrease was the loss of amacrine cells located in the inner nuclear layer. Photoreceptors were also found to potentially decrease in number, but at a later stage. ERG recordings revealed decreases in amplitudes of b-waves and oscillatory potentials in blind birds, but not in sighted. Both histology and ERG findings support the idea that the inner retinal cells are affected. The results indicate that degeneration in the Smoky Joe retina occurs mostly within the inner nuclear layer affecting amacrine cells. This hampers the functional capacity of the retina, causing blindness

Energy harvesting half-duplex AF power splitting protocol relay network over rician channel in case of maximizing capacity

In this letter, we propose a novel power splitting protocol for energy harvesting half-duplex AF relaying communication systems. In our proposed system, the relay harvests energy from the source transmissions, by employing adaptive PS protocol, for powering the retransmissions to the destination. The proposed model system is investigated in cases maximize and non-maximize ergodic capacity. Firstly, we perform the analytical mathematical analysis for deriving the integral closed-form expression of the outage probability and the ergodic capacity. Then, the analytical analysis of the system performance can be convinced by Monte-Carlo simulation with helping Mat Lab software. Finally, the numerical analysis provides practical insights into the effect of various system parameters on the system performance of the proposed system. This paper can be considered as a recommendation for the energy harvesting communication network