Stabilization and mobility of the head and trunk in vervet monkeys (Cercopithecus aethiops) during treadmill walks and gallops.
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The brain requires internal or external reference frames to determine body orientation in space. These frames may change, however, to meet changing conditions. During quadrupedal overground locomotion by monkeys, the head rotates on a stabilized trunk during walking, but the trunk rotates on a stabilized head during galloping. Do the same movement patterns occur during in-place locomotion? Head and trunk pitch rotations were measured, and yaw and roll rotations estimated from cine films of three adult vervet monkeys (Cercopithecus aethiops L. 1758) walking and galloping quadrupedally on a treadmill. Head and trunk rotational patterns during treadmill walks were comparable to the patterns found during overground walks. The rotational velocities of these segments during both treadmill walks and gallops were also comparable to the velocities found during natural locomotion. By contrast, whereas head and trunk rotational patterns during treadmill gallops did occur that were comparable to the patterns practiced during overground gallops, a significantly different pattern involving large and simultaneous head and trunk rotations was more commonly observed. Simultaneous head and trunk rotations may be possible during treadmill gallops because the fixed visual surround is providing an adequate spatial reference frame. Alternatively, or in addition to this visual information, a re-weighting in other sensory modalities may be occurring. Specifically, the vestibular inputs used during overground locomotion to reference gravity or a gravity-derived vector may become less important than proprioceptive inputs that are using the treadmill belt surface as a reference. Regardless, the spatial reference frame being used, blinks that occur at specific times during the largest head yaw rotations may be necessary to avoid the initiation of unwanted and potentially destabilizing lateral sway brought on by sudden increases in optic flow velocity. (+info)
The Jak-STAT pathway stimulated by interferon alpha or interferon beta.
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Type I interferons, such as interferon alpha and interferon beta (IFN-alpha and beta), signal through a Janus kinase (Jak) to signal transduction and activator of transcription (STAT) pathway to stimulate gene expression. In response to ligand binding, the receptors dimerize, Jaks phosphorylate STAT1 and STAT2, which then dimerize and interact with a third transcriptional regulator IFN regulatory factor 9 (IRF9) to stimulate gene expression. IFN-alpha is the main innate antiviral cytokine and is essential for effective immune response to viral infection. The animation shows activation of STAT-responsive gene expression in response to type I IFNs. (+info)
The Jak-STAT pathway stimulated by interferon gamma.
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Different cytokines stimulate the Janus kinase (Jak) and signal transducer and activator of transcription (STAT) pathway. Interferon gamma (IFN-gamma) is a type II interferon that triggers antiviral and adaptive immune responses through a Jak-STAT signaling pathway. These pathways involve a similar paradigm whereby cytokine binding to the receptor activates the Jaks, which phosphorylate STATs leading to their dimerization, translocation to the nucleus, and activation of their transcription factor activity. The animation shows binding of IFN-gamma and dimerization of the receptors, activation of Jak1 and Jak2, and phosphorylation of STAT1 leading to dimerization, translocation to the nucleus, and stimulation of target gene transcription. (+info)
The Jak-STAT pathway stimulated by interleukin 6.
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Signal transducer and activator of transcription 3 (STAT3) is widely expressed and activated by a variety of growth-regulating signals as well as diverse cytokines that use gp130 signaling receptors. STAT3 is critical for embryonic development and stem cell biology, as well as inflammation, growth regulation, and multiple immune regulatory and homeostatic functions. The animation shows activation of STAT3 in response to interleukin 6 (IL6), a cytokine involved in triggering inflammation. (+info)
Encoding of natural scene movies by tonic and burst spikes in the lateral geniculate nucleus.
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The role of the lateral geniculate nucleus (LGN) of the thalamus in visual encoding remains an open question. Here, we characterize the function of tonic and burst spikes in cat LGN X-cells in signaling features of natural stimuli. A significant increase in bursting was observed during natural stimulation (relative to white noise stimulation) and was linked to the strong correlation structure of the natural scene movies. Burst responses were triggered by specific stimulus events consisting of a prolonged inhibitory stimulus, followed by an excitatory stimulus, such as the movement of an object into the receptive field. LGN responses to natural scene movies were predicted using an integrate-and-fire (IF) framework and compared with experimentally observed responses. The standard IF model successfully predicted LGN responses to natural scene movies during tonic firing, indicating a linear relationship between stimulus and response. However, the IF model typically underpredicted the LGN response during periods of bursting, indicating a nonlinear amplification of the stimulus in the actual response. The addition of a burst mechanism to the IF model was necessary to accurately predict the entire LGN response. These results suggest that LGN bursts are an important part of the neural code, providing a nonlinear amplification of stimulus features that are typical of the natural environment. (+info)
Tobacco use in popular movies during the past decade.
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OBJECTIVE: The top 50 commercially successful films released per year from 1991 to 2000 were content coded to assess trends in tobacco use over time and attributes of films predictive of higher smoking rates. DESIGN: This observational study used media content analysis methods to generate data about tobacco use depictions in films studied (n = 497). Films are the basic unit of analysis. Once films were coded and preliminary analysis completed, outcome data were transformed to approximate multivariate normality before being analysed with general linear models and longitudinal mixed method regression methods. MAIN OUTCOME MEASURES: Tobacco use per minute of film was the main outcome measure used. Predictor variables include attributes of films and actors. Tobacco use was defined as any cigarette, cigar, and chewing tobacco use as well as the display of smoke and cigarette paraphernalia such as ashtrays, brand names, or logos within frames of films reviewed. RESULTS: Smoking rates in the top films fluctuated yearly over the decade with an overall modest downward trend (p < 0.005), with the exception of R rated films where rates went up. CONCLUSIONS: The decrease in smoking rates found in films in the past decade is modest given extensive efforts to educate the entertainment industry on this issue over the past decade. Monitoring, education, advocacy, and policy change to bring tobacco depiction rates down further should continue. (+info)
Nuclear receptor and transcriptional complex cycles.
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Transcriptional regulation by ligand-activated nuclear receptors, also known as steroid receptors, is a highly dynamic process. Nuclear receptors are intracellular proteins that reside in either the cytoplasm or nucleus in the inactive state. The interaction of this family of receptors with the promoters of target genes and with various proteins involved in stimulating gene expression is governed by binding to lipid soluble ligands. The animation, based on experiments following the dynamic interactions of the glucocorticoid receptor or the estrogen receptor with DNA, shows nuclear estrogen receptor and its interaction with a short two-nucleosome fragment of chromatin in the absence and presence of estrogen. The events that occur on the DNA are represented by the ordered recruitment of protein components to a larger macromolecular complex. The associated table describes the proteins and multimolecular complexes that participate in the nuclear receptor-chromatin cycles. (+info)
Phosphorelay signaling in yeast in response to changes in osmolarity.
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In the yeast, Saccharomyces cerevesiae, phosphorelay signaling systems that involve a three-step His-Asp-His-Asp phosphotransfer are involved in transmitting signals in response to cellular stress. The animation shows one example of such a phosphorelay system involved in yeast responses to changes in osmolarity. Under conditions of low osmolarity, a histidine-aspartate phosphorelay pathway transmits information that deactivates one signaling pathway and activates gene expression through another pathway. In response to high osmolarity, the Sln1 kinase that initiates the phosphorelay is inhibited and the Hog1 mitogen-activated protein kinase cascade is active. (+info)