Control dynamics of severe acute respiratory syndrome transmission

Severe acute respiratory syndrome (SARS) is a serious disease with many puzzling features. We present a simple, dynamic model to assess the epidemic potential of SARS and the effectiveness of control measures. With this model, we analysed the SARS epidemic data in Beijing. The data fitting gives the basic case reproduction number of 2.16 leading to the outbreak, and the variation of the effective reproduction number reflecting the control effect. Noticeably, our study shows that the response time and the strength of control measures have significant effects on the scale of the outbreak and the lasting time of the epidemic.

Polymorphisms in the C-type lectin genes cluster in chromosome 19 and predisposition to severe acute respiratory syndrome coronavirus (SARS-CoV) infection

Background: Polymorphisms of CLEC4M have been associated with predisposition for infection by the severe acute respiratory syndrome coronavirus (SARS-CoV). DC-SIGNR, a C-type lectin encoded by CLEC4M, is a receptor for the virus. A variable number tandem

Effect of paradoxical sleep deprivation and stress on passive avoidance behavior

Previous studies have shown that several types of stress can induce memory impairment. However, the memory effects of paradoxical sleep deprivation (PSD), a stressor in itself, are unclear. We therefore compared passive avoidance behavior of rats undergoing PSD and PSD stress yoked-control (PSC) using the "reversed flowerpot method." When rats were kept isolated on a PSC platform for 24 It immediately after criterion training, retention trials showed impaired aversive memory storage. When delayed for 24 h after criterion training, PSC stress did not disrupt retention performance. In rats subjected to PSD, either immediately or 24 It after criterion training, there was no disruption of aversive memory consolidation. These results suggest that, during stress, paradoxical sleep plays a role in erasing aversive memory traces, in line with the theory that we "dream in order to forget." (C) 2003 Elsevier Inc. All rights reserved.

Age-related effects of bilateral frontal eye fields lesions on rapid eye movements during REM sleep in rhesus monkeys

Rapid eye movement (REM) is one of the most characteristic features of REM sleep, but the mechanisms underlying its regulation remain unclear. The present study aims to investigate whether the frontal eye field (FEF) is involved in the regulation of the r

Assessing functioning of the prefrontal cortical subregions with auditory evoked potentials in sleep-wake cycle

Our previously observations showed that the amplitude of cortical evoked potentials to irrelevant auditory stimulus (probe) recorded from several different cerebral areas was differentially modulated by brain states. At present study, we simultaneously re

Characterization of the sleep architecture in two species of fruit bat

Bats (Chiroptera) are the second-most abundant mammalian order in the world, occupying a diverse range of habitats and exhibiting many different life history traits. In order to contribute to this highly underrepresented group we describe the sleep architecture of two species of frugivorous bat, the greater short-nosed fruit bat (Cynopterus sphinx) and the lesser dawn fruit bat (Eonycteris spelaea). Electroencephalogram (EEG) and electromyogram (EMG) data were recorded from multiple individuals (>= 5) by telemetry over a 72-h period in a laboratory setting with light/dark cycles equivalent to those found in the wild. Our results show that over a 24-h period both species spent more time asleep than awake (mean 15 h), less than previous reported for Chiroptera (20 h). C sphinx spent significantly more of its non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM) quotas during the light phase, while E. spelaea divided its sleep-wake architecture equally between both light and dark phases. Comparing the sleep patterns of the two species found that C. sphinx had significantly fewer NREM and REM episodes than E. spelaea but each episode lasted for a significantly longer period of time. Potential hypotheses to explain the differences in the sleep architecture of C. sphinx with E. spelaea, including risk of predation and social interaction are discussed. (C) 2010 Published by Elsevier B.V.

Sleeping sites, sleeping trees, and sleep-related behaviors of black crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang, central Yunnan, China

Data on sleep-related behaviors were collected for a group of central Yunnan black crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang, Yunnan, China from March 2005 to April 2006. Members of the group usually formed four sleeping units (adult male and juvenile, adult female with one semi-dependent black infant, adult female with one dependent yellow infant, and subadult male) spread over different sleeping trees. Individuals or units preferred specific areas to sleep; all sleeping sites were situated in primary forest, mostly (77%) between 2,200 and 2,400 m in elevation. They tended to sleep in the tallest and thickest trees with large crowns on steep slopes and near important food patches. Factors influencing sleeping site selection were (1) tree characteristics, (2) accessibility, and (3) easy escape. Few sleeping trees were used repeatedly by the same or other members of the group. The gibbons entered the sleeping trees on average 128 min before sunset and left the sleeping trees on average 33 min after sunrise. The lag between the first and last individual entering the trees was on average 17.8 min. We suggest that sleep-related behaviors are primarily adaptations to minimize the risk of being detected by predators. Sleeping trees may be chosen to make approach and attack difficult for the predator, and to provide an easy escape route in the dark. In response to cold temperatures in a higher habitat, gibbons usually sit and huddle together during the night, and in the cold season they tend to sleep on ferns and/or orchids.

Generation of recombinant monoclonal antibodies to study structure-function of envelope protein VP28 of white spot syndrome virus from shrimp

White spot syndrome virus (WSSV) is a major pathogen in shrimp aquaculture. VP28 is one of the most important envelope proteins of WSSV. In this study, a recombinant antibody library, as single-chain fragment variable (scFv) format, displayed on phage was constructed using mRNA from spleen cells of mice immunized with-full-length VP28 expressed in Escherichia coli. After several rounds of panning, six scFv antibodies specifically binding to the epitopes in the N-terminal, middle, and C-terminal regions of VP28, respectively, were isolated from the library. Using these scFv antibodies as tools, the epitopes in VP28 were located on the envelope of the virion by immuno-electron Microscopy, Neutralization assay with these antibodies in vitro suggested that these epitopes may not be the attachment site of WSSV to host cell receptor. This study provides a new way to investigate the structure and function of the envelope proteins of WSSV. (c) 2008 Published by Elsevier Inc.

Electroless-plated gold films for sensitive surface plasmon resonance detection of white spot syndrome virus

The paper describes the rapid and label-free detection of the white spot syndrome virus (WSSV) using a surface plasmon resonance (SPR) device based on gold films prepared by electroless plating. The plating condition for obtaining films suitable for SPR measurements was optimized. Gold nanoparticles adsorbed on glass slides were characterized by transmission electron microscopy (TEM). Detection of the WSSV was performed through the binding between WSSV in solution and the anti-WSSV single chain variable fragment (scFv antibody) preimmobilized onto the sensor surface. Morphologies of the as-prepared gold films, gold films modified with self-assembled alkanethiol monolayers, and films covered with antibody were examined using an atomic force microscope (AFM). To demonstrate the viability of the method for real sample analysis, WSSV of different concentrations present in a shrimp hemolymph matrix was determined upon optimizing the surface density of the antibody molecules. The SPR device based on the electroless-plated gold films is capable of detecting concentration of WSSV as low as 2.5 ng/mL in 2% shrimp hemolymph, which is one to two orders of magnitude lower than the level measurable by enzyme-linked immunosorbant assays. (c) 2007 Elsevier B.V. All rights reserved.

A new fluorescent quantitative PCR-based in vitro neutralization assay for white spot syndrome virus

A fluorescent quantitative PCR (FQ-PCR) assay utilizing SYBR green I dye is described for quantitation of white spot syndrome virus (WSSV) particles isolated from infected crayfish, Cambarus clarkii. For this assay, a primer set was designed which amplifies, with high efficiency and specificity, a 129 bp target sequence within ORF167 of the WSSV genome. Conveniently, WSSV particles can be added into the FQ-PCR assay with a simple and convenient method to release its DNA. To establish the basis for an in vitro neutralization test, primary cultures of shrimp cells were challenged with WSSV that had been incubated with a polyclonal anti-WSSV serum or with control proteins. The number of WSSV particles released from the cells after these treatments were assayed by FQ-PCR. This test may serve as a method to screen monoclonal antibody pools or recombinant antibody pools for neutralizing activity prior to in vivo animal experiments. (c) 2007 Elsevier B.V. All rights reserved.

Influence of selected Indian immunostimulant herbs against white spot syndrome virus (WSSV) infection in black tiger shrimp, Penaeus monodon with reference to haematological, biochemical and immunological changes

Immunostimulants are the substances, which enhance the non-specific defence mechanism and provide resistance against the invading pathogenic micro-organism. In order to increase the immunity of shrimps against the WSSV, the methanolic extracts of five different herbal medicinal plants like Cyanodon dactylon, Aegle marmelos, Tinospora cordifolia, Picrorhiza kurooa and Eclipta alba were selected and mixed thoroughly in equal proportion. The mixed extract was supplemented with various concentrations viz. 100 (A), 200 (B), 400 (C), and 800 (D) mg kg(-1) through artificial diets individually. The prepared diets (A-D) were fed individually to WSSV free healthy shrimp Penaeus monodon with an average weight of 8.0 +/- 0.5 g for 25 days. Control diet (E), devoid of herbal extract was also fed to shrimps simultaneously. After 25 days of feeding experiment, the shrimps were challenged with WSSV, which were isolated and propagated from the infected crustaceans. The shrimps succumbed to death within 7 days when fed on no herbal immunostimulant diet (E). Among the different concentrations of herbal immunostimulant supplemented diets, the shrimps fed on diet D (800 mg kg(-1)) significantly (P < 0.0001) had more survival (74%) and reduction in the viral load. Also the better performance of haematological, biochemical and immunological parameters was found in the immunostimulant incorporated diets fed shrimps. The present work revealed that the application of herbal immunostimulants will be effective against shrimp viral pathogenesis and they can be recommended for shrimp culture. (c) 2006 Published by Elsevier Ltd.