Generation of recombinant influenza A virus without M2 ion-channel protein by introduction of a point mutation at the 5′ end of the viral intron

The aim of this study was to inhibit influenza virus M2 protein expression by mutating the splicing signal of the M gene. Mutations were introduced into the GU dinucleotide sequence at the 5′-proximal splicing site of the M gene (corresponding to nt 52-53 of M cRNA). Transfected cells expressing mutated M viral ribonucleoproteins failed to generate M2 mRNA. Interestingly, recombinant viruses with mutations at the dinucleotide sequence were viable, albeit attenuated, in cell culture. These recombinants failed to express M2 mRNA and M2 protein. These observations demonstrated that the GU invariant dinucleotide sequence at the 5′-proximal splicing site of M gene is essential for M2 mRNA synthesis. These results also indicated that the M2 ion-channel protein is critical, but not essential, for virus replication in cell culture. This approach may provide a new way of producing attenuated influenza A virus. © 2005 SGM.postprin

Selective over-expression of endothelin-1 in endothelial cells exacerbates inner retinal edema and neuronal death in ischemic retina

The level of endothelin-1 (ET-1), a potent vasoconstrictor, was associated with retinopathy under ischemia. The effects of endothelial endothelin-1 (ET-1) over-expression in a transgenic mouse model using Tie-1 promoter (TET-1 mice) on pathophysiological changes of retinal ischemia were investigated by intraluminal insertion of a microfilament up to middle cerebral artery (MCA) to transiently block the ophthalmic artery. Two-hour occlusion and twenty-two-hour reperfusion were performed in homozygous (Hm) TET-1 mice and their non-transgenic (NTg) littermates. Presence of pyknotic nuclei in ganglion cell layer (GCL) was investigated in paraffin sections of ipsilateral (ischemic) and contralateral (non-ischemic) retinae, followed by measurement of the thickness of inner retinal layer. Moreover, immunocytochemistry of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS) and aquaporin-4 (AQP4) peptides on retinal sections were performed to study glial cell reactivity, glutamate metabolism and water accumulation, respectively after retinal ischemia. Similar morphology was observed in the contralateral retinae of NTg and Hm TET-1 mice, whereas ipsilateral retina of NTg mice showed slight structural and cellular changes compared with the corresponding contralateral retina. Ipsilateral retinae of Hm TET-1 mice showed more significant changes when compared with ipsilateral retina of NTg mice, including more prominent cell death in GCL characterized by the presence of pyknotic nuclei, elevated GS immunoreactivity in Müller cell bodies and processes, increased AQP-4 immunoreactivity in Müller cell processes, and increased inner retinal thickness. Thus, over-expression of endothelial ET-1 in TET-1 mice may contribute to increased glutamate-induced neurotoxicity on neuronal cells and water accumulation in inner retina leading to edema. © 2011 Cheung et al.published_or_final_versio

A novel peak-windowing technique for WCDMA systems

In Wideband Code Division Multiple Access (WCDMA), the high crest factor (CF) in the downlink signal has imposed a tight requirement on the linearity characteristic of the transmitter power amplifiers (PAs). This paper proposes a new peak-windowing technique to reduce the CF of a WCDMA signal. Computer-simulation tests have been carried out to study the effects of the proposed technique on the downlink signal of a WCDMA system. Results have shown that the performance of the technique, in terms of reduction in the CF, the error-vector-magnitude (EVM), the peak-code-domain error (PCDE), the adjacent-channel-leakage power ratio (ACLR) and the bit-error rate (BER) performance, are superior to other clipping and/or windowing techniques studied in this paper. © 2006 IEEE.link_to_subscribed_fulltex

Fuzzy logic adaptive handoff algorithm

In this paper, a handoff algorithm referred to as the Fuzzy Adaptive Averaging-interval and Hysteresis-threshold handoff (FAAH) is introduced. The design of the algorithm is intended to be used under lognormal fading environment. The algorithm consists of two fuzzy logic controllers. The first controller takes into the account for signal variation and to change the averaging interval (AVG) accordingly. The second controller dynamically adapts the hysteresis level (HYS) with signal differences between two stations. Conventional algorithms with fixed signal averaging interval and/or fixed hysteresis level are lack of flexibility under changing mobile environment. The FAAH is designed to strike a balance among handoff frequency, averaging delay, and the chance of lost call. Four experiments were performed: Constant AVG and HYS, Fuzzy controls on AVG and constant HYS, Fuzzy controls on HYS and constant AVG, and FAAH. The experimental results demonstrated that FAAH enhances the system handoff performance over conventional algorithms by about 50%

Plasma fibrinogen level: An independent risk factor for long-term survival in Chinese patients with peripheral artery disease?

Fibrinogen, an inflammatory marker as well as a fundamental part of the coagulation cascade, is suggested to play a significant role in the pathogenesis of atherosclerosis and complications of atherothrombotic diseases. The aim of this study was to determine if plasma fibrinogen is an independent risk factor for long-term survival in patients with peripheral artery disease (PAD). Altogether, 139 Chinese patients (88 men, 51 women) with PAD were consecutively recruited for the study. Atherothrombotic risk factors and fibrinogen levels were determined at presentation, and all patients were followed up for mortality prospectively. The mean follow-up was 6 years. All variables were first correlated with survival rates using Kaplan-Meier analysis and compared by means of the log-rank test. Significant risk factors were identified, and multivariate Cox regression analysis was used to evaluate the independent contribution of the fibrinogen level to the risk of mortality. During follow-up, 95 patients (68.3%) died. The overall survival rate was 77.7% at 3 years, 56.8% at 5 years, and 31.2% at 10 years (standard errors 0.05, 0.06, and 0.07, respectively). All-cause mortality rate increased with an elevated fibrinogen level. Eighty percent of patients with a fibrinogen level > 3.4 g/L had a survival time of less than 3 years (p = 0.002). This relation was also demonstrated within patients with critical ischemia. The plasma fibrinogen level was thus identified as an independent risk factor for mortality in PAD patients after adjusting for confounding factors. © 2005 by the Société Internationale de Chirurgie.link_to_subscribed_fulltex