In Silico Analysis and Experimental Evaluation of Ester Prodrugs of Ketoprofen for Oral Delivery: With a View to Reduce Toxicity

The present research aimed to synthesize ketoprofen prodrugs and to demonstrate their potentiality for oral treatment to treat chronic inflammation by reducing its hepatotoxicity and gastrointestinal irritation. Methyl 2-(3-benzoyl phenyl) propanoate, ethyl 2-(3-benzoyl phenyl) propanoate and propyl 2-(3-benzoyl phenyl) propanoate was synthesized by esterification and identified by nuclear magnetic resonance (1HNMR) and infrared (IR) spectrometric analysis. In silico SwissADME and ProTox-II analysis stated methyl derivative as ideal candidate for oral absorption, having a >30-fold LD50 value compared to ketoprofen with no hepatotoxicity. Moreover, in vivo hepatotoxicity study demonstrates that these ester prodrugs have significantly lower effects on liver toxicity compared to pure ketoprofen. Furthermore, ex vivo intestinal permeation enhancement ratio was statistically significant (* p < 0.05) compared to ketoprofen. Likewise, the prodrugs were found to exhibit not only remarkable in vitro anti-proteolytic and lysosomal membrane stabilization potentials, but also significant efficiency to alleviate pain induced by inflammation, as well as central and peripheral stimulus in mice model in vivo. These outcomes recommend that ketoprofen ester prodrugs, especially methyl derivative, can be a cost-effective candidate for prolonged treatment of chronic inflammatory diseases.

Circulating HMGB1 is elevated in veterans with Gulf War Illness and triggers the persistent pro-inflammatory microglia phenotype in male C57Bl/6J mice

Gulf War Illness (GWI) is a chronic, multi-symptom peripheral and CNS condition with persistent microglial dysregulation, but the mechanisms driving the continuous neuroimmune pathology are poorly understood. The alarmin HMGB1 is an autocrine and paracrine pro-inflammatory signal, but the role of circulating HMGB1 in persistent neuroinflammation and GWI remains largely unknown. Using the LPS model of the persistent microglial pro-inflammatory response, male C57Bl/6J mice injected with LPS (5 mg/kg IP) exhibited persistent changes in microglia morphology and elevated pro-inflammatory markers in the hippocampus, cortex, and midbrain 7 days after LPS injection, while the peripheral immune response had resolved. Ex vivo serum analysis revealed an augmented pro-inflammatory response to LPS when microglia cells were cultured with the 7-day LPS serum, indicating the presence of bioactive circulating factors that prime the microglial pro-inflammatory response. Elevated circulating HMGB1 levels were identified in the mouse serum 7 days after LPS administration and in the serum of veterans with GWI. Tail vein injection of rHMGB1 in male C57Bl/6 J mice elevated TNFα mRNA levels in the liver, hippocampus, and cortex, demonstrating HMGB1-induced peripheral and CNS effects. Microglia isolated at 7 days after LPS injection revealed a unique transcriptional profile of 17 genes when compared to the acute 3 H LPS response, 6 of which were also upregulated in the midbrain by rHMGB1, highlighting a distinct signature of the persistent pro-inflammatory microglia phenotype. These findings indicate that circulating HMGB1 is elevated in GWI, regulates the microglial neuroimmune response, and drives chronic neuroinflammation that persists long after the initial instigating peripheral stimulus.

Investigating Arousal, Saccade Preparation, and Global Luminance Effects on Microsaccade Behavior

Microsaccades, small saccadic eye movements occurring during fixation, have been suggested to be modulated by various sensory, cognitive, and affective processes relating to arousal. Although the modulation of fatigue-related arousal on microsaccade behavior has previously been characterized, the influence of other aspects of arousal, such as emotional arousal, is less understood. Moreover, microsaccades are modulated by cognitive processes (e.g., voluntary saccade preparation) that could also be linked to arousal. To investigate the influence of emotional arousal, saccade preparation, and global luminance levels on microsaccade behavior, emotional auditory stimuli were presented prior to the onset of a fixation cue whose color indicated to look either at the peripheral stimulus (pro-saccade) or in the opposite direction of the stimulus (anti-saccade). Microsaccade behavior was found to be significantly modulated by saccade preparation and global luminance level, but not emotional arousal. In the pro- and anti-saccade task, microsaccade rate was lower during anti-saccade preparation as compared to pro-saccade preparation, though microsaccade dynamics were comparable during both trial types. Our results reveal a differential role of arousal linked to emotion, fatigue, saccade preparation, and global luminance level on microsaccade behavior.

Sustained spatial attention accounts for the direction bias of human microsaccades

Small ballistic eye movements, so called microsaccades, occur even while foveating an object. Previous studies using covert attention tasks have shown that shortly after a symbolic spatial cue, specifying a behaviorally relevant location, microsaccades tend to be directed toward the cued location. This suggests that microsaccades can serve as an index for the covert orientation of spatial attention. However, this hypothesis faces two major challenges: First, effects associated with visual spatial attention are hard to distinguish from those that associated with the contemplation of foveating a peripheral stimulus. Second, it is less clear whether endogenously sustained attention alone can bias microsaccade directions without a spatial cue on each trial. To address the first issue, we investigated the direction of microsaccades in human subjects while they attended to a behaviorally relevant location and prepared a response eye movement either toward or away from this location. We find that directions of microsaccades are biased toward the attended location rather than towards the saccade target. To tackle the second issue, we verbally indicated the location to attend before the start of each block of trials, to exclude potential visual cue-specific effects on microsaccades. Our results indicate that sustained spatial attention alone reliably produces the microsaccade direction effect. Overall, our findings demonstrate that sustained spatial attention alone, even in the absence of saccade planning or a spatial cue, is sufficient to explain the direction bias observed in microsaccades.

Eccentricity Effect of Deformation Detection for Radial Frequency Patterns With Their Centers at Fixation Point

We measured the eccentricity effect of deformation thresholds of circular contours for two types of the radial frequency (RF) patterns with their centers at the fixation point: constant circular contour frequency (CCF) RF patterns and constant RF magnified (retino-cortical scaling) RF patterns. We varied the eccentricity by changing the mean radius of the RF patterns while keeping the centers of the RF patterns at the fixation point. Our peripheral stimulus presentation was distinguished from previous studies which have simply translated RF patterns at different locations in the visual field. Sensitivity for such shape discrimination fell off as the moderate and high CCF patterns were presented on more eccentric sites but did not as the low CCF patterns. However, sensitivity held constant as the magnified RF patterns were presented on more eccentric sites, indicating that the eccentricity effects observed for the high and moderate CCF patterns were neutralized by retinocortical mapping. Notably, sensitivity for the magnified RF patterns with large radii (4°–16°) presented in the peripheral field revealed a similar RF dependence observed for RF patterns with small radii (0.25°–1.0°) presented at the fovea in previous studies.

Two “Inhibitions of Return” Bias Orienting Differently

Inhibition of return (IOR) is usually viewed as an inhibitory aftermath of visual orienting typically seen in the form of slower responses to targets presented in a previously attended location or object (Posner &amp; Cohen, 1984; Posner et al., 1985). Using the diagnostic patterns obtained when peripheral onset or central arrow targets are used, we have seen that there are two forms of inhibitory aftereffect: one caused by a peripheral stimulus whereby the effect is to decrease the efficiency of subsequent visual processing in the proximity of this stimulus (input effect); the second caused by oculomotor activation whereby the effect is a motor bias (output effect). These are distinguished clearly by whether the effect can only be measured by peripheral targets (input form when the reflexive oculomotor system is suppressed) or by whether there are roughly equivalent delays in response whether the targets are central or peripheral (output form when the reflexive oculomotor system is not suppressed). When performance is represented in speed-accuracy space the input form is manifest as a shift from one speed-accuracy tradeoff function to a less efficient one representing degraded or delayed processing of cued targets while the output form entails no shift in the function, but instead a movement along it (a response bias). Both forms bias orienting and hence can perform the novelty seeking function attributed to the inhibitions in the seminal papers: the input form does so by biasing perception, whereas the output form does so by biasing action.

Associations between neonatal cry acoustics and visual attention during the first year

It has been suggested that early cry parameters are connected to later cognitive abilities. The present study is the first to investigate whether the acoustic features of infant cry are associated with cognitive development already during the first year, as measured by oculomotor orienting and attention disengagement. Cry sounds for acoustic analyses (fundamental frequency; F0) were recorded in two neonatal cohorts at the age of 0-5 days (Tampere, Finland) or at 6 weeks (Cape Town, South Africa). Eye tracking was used to measure oculomotor orienting to peripheral visual stimuli and attention disengagement from central stimuli at 8 months (Tampere) or at 6 months (Cape Town) of age. In the Tampere cohort, a marginal positive correlation between fundamental frequency of cry (F0) and visual attention disengagement was observed; infants with a higher neonatal F0 were slower to shift gaze away from the central stimulus to the peripheral stimulus. However, a similar correlation was not observed in the Cape Town cohort. No associations between F0 and oculomotor orienting were observed in either cohort. We discuss possible factors influencing the discrepancy in results between the cohorts and suggest directions for future research investigating the potential of early cry analysis in predicting later cognitive development.

Effect of visual attention and horizontal vergence in three-dimensional space on occurrence of optokinetic nystagmus

OKN corresponding to the motion of the fixating area occurs when a stimulus has two areas separated in depth containing motion in different directions. However, when attention and vergence are separately directed to areas with different motions and depths, it remains unclear which property of attention and vergence is prioritized to initiate OKN. In this study, we investigated whether OKN corresponding to motion in the attending or fixating area occurred when two motions with different directions were presented in the central and peripheral visual fields separated in depth. Results show that OKN corresponding to attended motion occurred when observers maintained vergence on the peripheral stimulus and attended to the central stimulus. However, OKN corresponding to each motion in the attending area and in the fixating area occurred when observers maintained vergence on the central stimulus and attended to the peripheral stimulus. The accuracy rate of the attentional task was the lowest in this condition. These results support the idea that motion in the attended area is essential for occurrence of OKN, and vergence and retinal position affect the strength of attention.

To look or not to look? Reward, selection history, and oculomotor guidance

The current eye-tracking study examined the influence of reward on oculomotor performance, and the extent to which learned stimulus-reward associations interacted with voluntary oculomotor control with a modified paradigm based on the classical antisaccade task. Participants were shown two equally salient stimuli simultaneously: a gray and a colored circle, and they were instructed to make a fast saccade to one of them. During the first phase of the experiment, participants made a fast saccade toward the colored stimulus, and their performance determined a (cash) bonus. During the second, participants made a saccade toward the gray stimulus, with no rewards available. On each trial, one of three colors was presented, each associated with high, low or no reward during the first phase. Results from the first phase showed improved accuracy and shorter saccade latencies on high-reward trials, while those from the second replicated well-known effects typical of the antisaccade task, namely, decreased accuracy and increased latency during phase II, even despite the absence of abrupt asymmetric onsets. Crucially, performance differences between phases revealed longer latencies and less accurate saccades during the second phase for high-reward trials, compared with the low- and no-reward trials. Further analyses indicated that oculomotor capture by reward signals is mainly found for saccades with short latencies, while this automatic capture can be overridden through voluntary control with longer ones. These results highlight the natural flexibility and adaptability of the attentional system, and the role of reward in modulating this plasticity. NEW & NOTEWORTHY Typically, in the antisaccade task, participants need to suppress an automatic orienting reflex toward a suddenly appearing peripheral stimulus. Here, we introduce an alternative antisaccade task without such abrupt onsets. We replicate well-known antisaccade effects (more errors and longer latencies), demonstrating the role of reward in developing selective oculomotor biases. Results highlight how reward and selection history facilitate developing automatic biases from goal-driven behavior, and they suggest that this process responds to individual differences in impulsivity.

Switch costs in inhibitory control and voluntary behavior: A computational study of the antisaccade task

An integral aspect of human cognition is the ability to inhibit habitual responses in order to initiate complex, rule-guided actions. Moreover, humans have also the ability to alternate between different sets of rules or tasks, at the cost of degraded performance when compared to repeating the same task, a phenomenon called the ‘task switch cost’. While it is recognized that switching between tasks requires often to inhibit habitual responses, the interaction between these two forms of cognitive control has been much less studied than each of them separately. Here, we use a computational model to draw a bridge between inhibitory control and voluntary action generation and thereby provide a novel account of seemingly paradoxical findings in the task switch literature. We investigated task switching in the mixed antisaccade task, in which participants are cued to saccade either in the same or in the opposite direction to a peripheral stimulus. Our model demonstrates that stopping a habitual action leads to increased inhibitory control that persists on the next trial. However, enhanced inhibition affects only the probability of generating habitual responses, and, contrary to previous accounts, cannot be characterized as proactive task interference. In addition, our model demonstrates that voluntary actions (but not habitual responses) are slower and more prompt to errors on switch trials compared to repeat trials. We conclude that precisely the interaction between these two effects explains a variety of contradictory findings reported in the literature.