Application of Whole Mouse Embryo Culture System on Stem Cell Research

The normal development of mouse embryo in vivo could be maintained in vitro up to 72 h in the presence of rat serum which is continuously supplied with the appropriate concentration of O₂ and CO₂. There are several applications of the whole mouse embryo culture model for study of cellular dynamics in hematopoiesis and its interaction with vasculogenesis. In this protocol, we have described details of manipulation techniques in combination with the whole embryo culture and also some advance techniques applied to the mouse embryo such as intra-cardiac inoculation of acetylated low density lipoprotein for cell-specific labeling and engraftment of donor yolk-sac from different genotype/phenotype mouse embryo onto the yolk-sac of host mouse for study of the dynamic distribution of hematopoietic cell.

Randomizing visual feedback in manual aiming: reminiscence of the previous trial condition and prior knowledge of feedback availability

A trial-by-trial analysis was used to systematically examine the influence of switching visual conditions on visual feedback utilization for a manual aiming movement. In experiment one, vision was randomly manipulated from trial to trial with no more than four consecutive trials in the same visual condition. In experiment two, participants were provided with certainty of visual feedback availability prior to every trial. Results of both studies revealed that movement endpoint variability was most associated with visual feedback availability on the previous trial. Furthermore, correlation analyses comparing movement trajectory at 25, 50 and 75% with movement end (i.e. 100%) revealed that the efficiency of online corrections also depends on the availability of visual feedback on the previous trial. These results suggest that the accuracy of an aiming movement is highly dependent on processing of offline visual information from the preceding trial. This study was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) awarded to Luc Tremblay.

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Non-Newtonian Bile Flow in Elastic Cystic Duct: One- and Three-Dimensional Modeling

Bile flow is thought to play an essential role in the pathophysiological genesis of cholelithiasis (gallstone formation) and in gallbladder pain. In this paper, we extend our previous study of the human biliary system (Li et al., 2007, J. Biomech. Eng., 129:164–173) to include two important factors: the non-Newtonian properties of bile, and elastic deformation of the cystic duct. A one-dimensional (1D) model is analyzed and compared with three-dimensional (3D) fluid–structure interaction simulations. It is found that non-Newtonian bile raises resistance to the flow of bile, which can be augmented significantly by the elastic deformation (collapse) of the cystic duct. We also show that the 1D model predicts the pressure drop of the cystic duct flow well for all cases considered (Newtonian or non-Newtonian flow, rigid or elastic ducts), when compared with the full 3D simulations.

Spontaneous reactions to health risk feedback: a network perspective

Research on the reception of health risk feedback has focused on the analysis of single, researcher-selected cognitive reactions. The full range of spontaneous reactions and their patterns have received little attention. The present paper explores content, interrelations, and adaptivity of spontaneous reactions to health risk feedback from a network perspective. Participants (n = 423) received blood pressure and cholesterol feedback and listed their thoughts afterwards. A network of reactions to health risk feedback was constructed from the responses. Emotions, risk feedback valence, future lifestyle, and expectedness emerged as strong and largely well-connected network nodes, while previously well-researched reactions like feedback acceptance formed small, less connected nodes. The majority of reaction patterns identified through the network appeared adaptive, even after negative feedback. The network provides a potentially useful tool for research and practice, highlighting previously neglected relevant reactions, and providing a group-level background against which individual reactions can be evaluated.

Working memory capacity,intelligence, and the magnitude of the attentional blink revisited

The attentional blink (AB) is a well-established phenomenon in the study of attention. This deficit in reporting the second of two targets presented in rapid serial visual presentation when it occurs 200–500 ms after the first is considered to reflect a fundamental limitation in attentional processing. However, we recently reported that some individuals do not show an AB, and presented psychophysiological evidence that target processing differs between blinkers and non-blinkers. One possibility is that non-blinkers may have a larger WM capacity, allowing better attentional control. Here we explore the relation between the magnitude of the AB, general intelligence, and different measures of working memory (WM) and short-term memory (STM) capacity. Surprisingly, no correlation was found between memory capacity measures and AB magnitude, raising doubts about the generalizability of earlier findings of such a relationship.

Dopamine and inhibitory action control: evidence from spontaneous eye blink rates

The inhibitory control of actions has been claimed to rely on dopaminergic pathways. Given that this hypothesis is mainly based on patient and drug studies, some authors have questioned its validity and suggested that beneficial effects of dopaminergic stimulants on response inhibition may be limited to cases of suboptimal inhibitory functioning. We present evidence that, in carefully selected healthy adults, spontaneous eyeblink rate, a marker of central dopaminergic functioning, reliably predicts the efficiency in inhibiting unwanted action tendencies in a stop-signal task. These findings support the assumption of a modulatory role for dopamine in inhibitory action control.

Interaural self-motion linear velocity thresholds are shifted by roll vection

The otolith organs respond equivalently to changes in gravitational force due to head tilt and to changes in inertial force due to linear acceleration. It has been shown that the central nervous system (CNS) uses internal models of the laws of physics to distinguish tilt from translation. Models with these internal models predict that illusory tilt, if large enough, will be accompanied by an illusion of linear motion. To investigate this prediction, we measured interaural, self-motion, direction-detection thresholds in darkness and with roll optokinetic stimulation. Each lateral translation consisted of a single cycle of sinusoidal acceleration, after which subjects indicated whether they translated to the left or right. We found that the interaural direction-detection threshold measured during clockwise and counterclockwise optokinetic stimulation shifted in opposite directions relative to thresholds in darkness. Using a generalized linear model, we determined that this finding was statistically significant (P < 0.005) and is consistent with the prediction that illusory tilt should be accompanied by a non-zero neural estimate of linear velocity that, if large enough (supra-threshold), contributes to translation perception.

Estimation of Breathing Rate from Respiratory Sinus Arrhythmia: Comparison of Various Methods

Although respiratory sinus arrhythmia (RSA) is a well-known and often studied phenomenon, methods to estimate (average) respiratory rate from heart rate variability via RSA have been investigated and published only sparsely. We reinvestigate three published techniques and contrast them to our own approaches. All methods were also evaluated for respiration signals to yield approximations of the true breathing rate for comparison. Our analyses are based on physiological recordings available at PhysioNet, an online database. Results show that the RSA of young supine subjects yields good approximations of mean respiratory rate in the case of time series longer than 1 min, while the estimations become noticeably less accurate for elderly persons. Our own “advanced counting method” produced the best results, and in addition principally permits even the definition of instantaneous respiratory rates. Consequently, it is recommended for further investigations.

The modulation of intermanual interactions during the specification of the directions of bimanual movements

In two experiments bimanual movements with various combinations of target directions were studied by means of the timed-response procedure. The findings revealed an adaptive modulation of intermanual interactions during direction specifications depending on particular target directions. For symmetric movements intermanual correlations of movement directions are positive, indicating a symmetric coupling. For parallel movements the positive intermanual correlations, observed at short preparation intervals, turn into negative correlations as the time available for motor preparation increases. Biases of mean directions, that can be observed for movements to targets with different eccentricities, reflect one or the other kind of coupling, symmetrical for symmetric target directions and parallel for parallel target directions. These biases are static, that is, they are present at long preparation times, and they are phasically enhanced at shorter preparation intervals. The task-adaptive modulation of intermanual interactions is superposed on a basic symmetry bias.

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RNAi-dependent and -independent antiviral phenotypes of chromosomally integrated shRNA clones: Role of VASP in respiratory syncytial virus growth

Stable RNA interference (RNAi) is commonly achieved by recombinant expression of short hairpin RNA (shRNA). To generate virus-resistant cell lines, we cloned a shRNA cassette against the phosphoprotein gene of respiratory syncytial virus (RSV) into a polIII-driven plasmid vector. Analysis of individual stable transfectants showed a spectrum of RSV resistance correlating with the levels of shRNA expressed from different chromosomal locations. Interestingly, resistance in a minority of clones was due to mono-allelic disruption of the cellular gene for vasodilator-stimulated phosphoprotein (VASP). Thus, pure clones of chromosomally integrated DNA-directed RNAi can exhibit gene disruption phenotypes resembling but unrelated to RNAi.

Eye-movements intervening between two successive sounds disrupt comparisons of auditory location

Many studies have investigated how saccades may affect the internal representation of visual locations across eye-movements. Here, we studied, instead, whether eye-movements can affect auditory spatial cognition. In two experiments, participants judged the relative azimuth (same/different) of two successive sounds presented from a horizontal array of loudspeakers, separated by a 2.5-s delay. Eye-position was either held constant throughout the trial (being directed in a fixed manner to the far left or right of the loudspeaker array) or had to be shifted to the opposite side of the array during the retention delay between the two sounds, after the first sound but before the second. Loudspeakers were either visible (Experiment 1) or occluded from sight (Experiment 2). In both cases, shifting eye-position during the silent delay-period affected auditory performance in thn the successive auditory comparison task, even though the auditory inputs to be judged were equivalent. Sensitivity (d′) for the auditory discrimination was disrupted, specifically when the second sound shifted in the opposite direction to the intervening eye-movement with respect to the first sound. These results indicate that eye-movements affect internal representation of auditory location.

Optical modulation of locomotion and energy expenditure at preferred transition speed

The effect of optical flow on locomotion stability and efficiency was evaluated at preferred walk-run transition speed (PTS). Seven participants were instructed to locomote (walk or run) at PTS, while looking at the end of a three-dimensional virtual corridor projected on a large screen. Three experimental conditions of optical flow were tested: optical flow velocity consistent with locomotion speed (C), optical flow velocity twice faster (F) or slower (S) than locomotion speed. They were contrasted with a control static flow condition. Transitions between patterns were more frequent in (C) than in the other conditions, suggesting that optical flow influenced the stability of locomotion. Moreover, kinematic analyses revealed a stronger destabilization of gait in (F), accompanied by a decrease in energy expenditure in that condition. These results suggest that optical flow influenced both energetic and gait components at PTS, encouraging the exploration and stabilization of the most economic behavior. The mutual dependency of the visual system, the locomotor system and the cardio-respiratory system is emphasized.

Novel preparation techniques for controlling microbubble uniformity: a comparison

In recent years, there has been increasing interest in the use of coated microbubbles as vehicles for ultrasound mediated targeted drug delivery. This application requires a high degree of control over the size and uniformity of microbubbles, in order to ensure accurate dosing of a given drug and to maximise delivery efficiency. Similarly, as more advanced imaging techniques are developed which exploit the complex nonlinear features of the microbubble signal and/or enable quantification of tissue perfusion, the ability to predetermine the acoustic response of a microbubble suspension is becoming increasingly important. Consequently, a number of new preparation technologies have been developed to meet the demand for improved control over microbubble characteristics. The aim of the work described in this paper was to compare a conventional microbubble preparation technique, sonication, with two more recent methods: coaxial electrohydrodynamic atomisation and microfluidic (T-junction) processing, in terms of their ability to produce bubbles which are sufficiently small and stable for in vivo use, microbubble uniformity, relative production rates and other practical and economic considerations.

How voluntary actions modulate time perception

Distortions of time perception are generally explained either by variations in the rate of pacing signals of an “internal clock”, or by lag-adaptation mechanisms that recalibrate the perceived time of one event relative to another. This study compares these accounts directly for one temporal illusion: the subjective compression of the interval between voluntary actions and their effects, known as ‘intentional binding’. Participants discriminated whether two cutaneous stimuli presented after voluntary or passive movements were simultaneous or successive. In other trials, they judged the temporal interval between their movement and an ensuing tone. Temporal discrimination was impaired following voluntary movements compared to passive movements early in the action-tone interval. In a control experiment, active movements without subsequent tones produced no impairment in temporal discrimination. These results suggest that voluntary actions transiently slow down an internal clock during the action-effect interval. This in turn leads to intentional binding, and links the effects of voluntary actions to the self.

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Banks, Repositories and Registries of Stem Cell Lines in Europe: Regulatory and Ethical Aspects

To overview banks, repositories and registries of stem cell lines in Europe excluding bone marrow and cord blood banks; to concisely discuss the most important scientific, regulatory and ethical aspects of stem cell banking in a manner understandable to a layperson, but remain detailed enough not to compromise thoroughness of information. Review of scientific publications, laws and ethical guidelines in this field up through September 2008; hearing the opinions of key persons working in stem cell banking. The article discusses the procedure of stem cell banking and related safety issues and reviews the regulation of stem cell banking at the regional (European) and the national level. Stem cell banking can help meet scientific and certain ethical imperatives, but is complicated in the context of heterogeneous laws, guidelines, and ethical standards. In the pluralistic European society with cultural diversity leading to heterogeneous laws, harmonisation of international guidelines and national laws regulating stem cell banking is needed, as well as mapping of implementation at the national level.

Serial blood cultures from canine stored whole blood held at room temperature for 24 h

To determine if 30- to 35-day-old units of canine stored whole blood held at room temperature over 24 h will reveal bacterial contamination when exposed to repeated sampling. The design of the study is prospective, controlled. Ten units of stored whole blood from ten client owned volunteer blood donor dogs were used. A sterile blood bag spike was inserted aseptically as a port for repeated sampling for culture into ten separate units of 30- to 35-day-old canine stored whole blood held at room temperature for 24 h. Aerobic and anaerobic bacterial culture samples were collected every 4 h over 24 h. No bacterial growth was detected in any sample at any time point from the ten bags used. Canine stored whole blood, collected and stored for 30 to 35 days according to accepted transfusion guidelines, can be aseptically spiked and held at room temperature for 24 h without evidence of bacterial contamination or proliferation.

The relationship between poor sleep and inhibitory functions indicated by event-related potentials

The present study focused on the relationship between normal variations of sleep and inhibitory functions as reflected in event-related potentials. For this reason one night of 21 healthy participants was analysed. After waking up all participants completed a visual Go/Nogo task. On the basis of a sleep disturbance index (SDI) the participants were separated into 8 SDI-good and 13 SDI-poor sleepers using a cluster analysis. The results showed that Nogo-N2 amplitude was smaller and Nogo-P3 latency longer in SDI-poor sleepers. Moreover, Go-P3 amplitude was smaller in SDI-poor sleepers. Performance parameters were not influenced by poor sleep. We concluded that poor sleep specifically affects the intensity of pre-motor inhibitory processes (Nogo-N2 amplitude), the speed to inhibit a motor response (Nogo-P3 latency) and the intensity of task-relevant information processing (Go-P3 amplitude). In further studies, it should be explored under which conditions such subliminal deficits also become relevant for overt behaviour.

Modelling the human pharyngeal airway: validation of numerical simulations using in vitro experiments

In the presented study, a numerical model which predicts the flow-induced collapse within the pharyngeal airway is validated using in vitro measurements. Theoretical simplifications were considered to limit the computation time. Systematic comparisons between simulations and measurements were performed on an in vitro replica, which reflects asymmetries of the geometry and of the tissue properties at the base of the tongue and in pathological conditions (strong initial obstruction). First, partial obstruction is observed and predicted. Moreover, the prediction accuracy of the numerical model is of 4.2% concerning the deformation (mean quadratic error on the constriction area). It shows the ability of the assumptions and method to predict accurately and quickly a fluid–structure interaction.

N-terminal of <Emphasis Type="Italic">Papaya ringspot virus</Emphasis> type-W (PRSV-W) helper component proteinase (HC-Pro) is essential for PRSV systemic infection in zucchini

The Papaya ringspot virus (PRSV) is one of the limiting factors affecting papaya and cucurbits production worldwide. PRSV belongs to the potyvirus genus which consists of 30% of known plant viruses. Two serological closely related strains, namely type-P and -W, have been reported. PRSV type-P infects both papaya and cucurbits, while type-W infects only cucurbits. The genome of PRSV Thailand isolate consists of a (+) RNA molecule of 10323 nucleotides, which is first translated into a single polypeptide and further cleaved by three viral encoded proteases into ten gene products. Helper-component proteinase (HC-Pro), which is encoded by the 2nd cistron of the potyviral genome, has been implicated in aphid transmission, viral movement, viral replication and suppression of host viral defense system. Studies of the Tobacco etch virus (TEV), Lettuce mosaic virus (LMV), Onion yellow dwarf virus (OYDV) and Wheat streak mosaic virus (WSMV) indicate that the N-terminal of HC-Pro is dispensable for systemic infection in their respective hosts. However, deletion analysis of the Tobacco vein mottling virus (TVMV) indicates otherwise. In this study, we examined whether HC-Pro is essential for PRSV systemic infection in cucurbits and the role of its N-terminal in systemic infection. Our results indicated that HC-Pro is indispensable for PRSV infection in zucchini. Deletion analysis of PRSV HC-Pro showed that deletion of as few as 54 amino acids at the N-terminal of HC-Pro completely abolished the infectivity of the corresponding cDNA clone. Therefore, it is proposed that the N-terminal of HC-Pro is involved in systemic infection of PRSV, in addition to its conserved function in aphid transmission.

Attention modulates the specificity of automatic imitation to human actors

The perception of actions performed by others activates one’s own motor system. Recent studies disagree as to whether this effect is specific to actions performed by other humans, an issue complicated by differences in perceptual salience between human and non-human stimuli. We addressed this issue by examining the automatic imitation of actions stimulated by viewing a virtual, computer-generated, hand. This stimulus was held constant across conditions, but participants’ attention to the virtualness of the hand was manipulated by informing some participants during instructions that they would see a “computer-generated model of a hand,” while making no mention of this to others. In spite of this attentional manipulation, participants in both conditions were generally aware of the virtualness of the hand. Nevertheless, automatic imitation of the virtual hand was significantly reduced––but not eliminated––when participants were told they would see a virtual hand. These results demonstrate that attention modulates the “human bias” of automatic imitation to non-human actors.