Embodied cognition is a theoretical framework which posits that cognitive function is intimately intertwined with the body and physical actions. Although the field of psychology is increasingly accepting embodied cognition as a viable theory, it has rarely been employed in the gerontological literature. However, embodied cognition would appear to have explanatory power for aging research given that older adults typically manifest concurrent physical and mental changes, and that research has indicated a correlative relationship between such changes. The current paper reviews age-related changes in sensory processing, mental representation, and the action-perception relationship, exploring how each can be understood through the lens of embodied cognition. Compared to younger adults, older adults exhibit across all three domains an increased tendency to favor visual processing over bodily factors, leading to the conclusion that older adults are less embodied than young adults. We explore the significance of this finding in light of existing theoretical models of aging and argue that embodied cognition can benefit gerontological research by identifying further factors that can explain the cause of age-related declines. Embodied cognition theory argues that cognitive and perceptual processes are grounded in the organism’s sensorimotor capacities. It rests upon a rejection of the classic cognitivist division between mind and body, and holds that the two are intertwined in often unexpected ways . Traditi1. However, insofar as it rejects some of the central tenets of classical cognitivist theory, embodied cognition retains something of an outsider status in cognitive science. Indeed, for some the ambiguous nature of embodied cognition makes it too difficult to effectively employ  an increased reliance on visual processing , and (2) a decreased reliance on bodily  factors. At the end of this review, we will discuss the significance of this finding and how it may affect existing models of sensorimotor processing in older adults.Embodied cognition theorists have argued that sensorimotor factors serve as the groundwork for cognition. For instance, concepts have been characterized as grounded in situated, bodily action and are instantiated by neural reactivations of sensorimotor cortices used in active sensorimotor function . This emWhile the sensory system is subject to age effects across all five senses , our focAlthough age-related unimodal sensory declines are of obvious importance, our perception of the world typically involves more than one sensory modality. Multisensory integration (MSI) is the combination of two or more sensory modalities into a unified percept, a process driven by a neuronal system designed to process multiple sensory inputs simultaneously . MSI is Research indicates that younger and older adults both benefit from multisensory inputs (compared to unisensory inputs) when those inputs provide redundant information, yet this benefit is even greater in the older adults cf., . For insThus, while older adults can gain from MSI-based facilitation effects, they also exhibit stronger debilitation under MSI-based distraction conditions. What explains these divergent effects? There are likely several contributing factors. First, with deficits in unimodal perception, older adults are likely compensating by relying on the additional information provided by MSI. Consider Second, when vision is one of the modalities being integrated, older adults often appear to prioritize it over audition and touch. Throughout this paper, we will be using the phrase visual dominance to describe this over-reliance on visual processing over other sensory modalities. It is important to point out that visual processing factors dominate over the other sensory modalities for all normally sighted humans, not just older adults . The finPrioritizing visual over somatosensory information may help explain why older adults exhibit balance control issues and increased falls . StandinYet this visual dominance affecting older adults is neither inevitable nor fixed. Recent research has shown that MSI in older adults is highly plastic, and MSI-based training can result in improved walking and balance performance . For insThe body schema and peripersonal space are concepts used to explain how humans understand the physical body and the external space immediately surrounding it. While these terms are treated as functionally distinct, they share many similarities and in fact are often used somewhat interchangeably. The body schema is the internalized ‘map’ of spatial relations for one’s own body based on kinesthetic, proprioceptive, and tactile information, which is ultimately used to facilitate successful action; peripersonal space, on the other hand, is the space immediately surrounding the body through which we interact with the surrounding environment. Ambiguity in the exact boundaries of these constructs is understandable: when examining the understanding of physical actions (a body schema question), that movement necessarily takes place in peripersonal space, and the influence of that space is difficult to disentangle from the body schema itself  space. One common difference is that in peripersonal space, young adults deploy attention asymmetrically, over-emphasizing the left visual field over the right. This is thought to occur because spatial attention in peripersonal  space is primarily controlled by the right-hemisphere . On taskAlthough these behavioral tests are in line with peripersonal representations changing with age, not all studies find age differences. Older adults have been found to exhibit leftward biases when drawing or arranging items in peripersonal space, similar to young adults . While tWith regard to the body schema proper, little research has directly explored how it may be affected by aging. Having detailed the age-related changes to sensory-level processing, we turn now to how aging alters mental representations based on that sensory processing. The embodied cognition framework regards mental concepts as either heavily interactive with sensorimotor systems or as directly related to sensorimotor function , wherebyMental imagery is the creation, maintenance, and activation of an internal representation. Although seemingly simple in definition, mental imagery depends upon multiple cognitive subcomponents including sensory processing , cognitive processing , and working memory , a 2D image of a single hand, and 3D whole-body image. Although age effects were evident across all three image types, older adults were significantly worse performing the whole-body rotations, with increasing reaction times and errors when rotating at larger angles. In this case, the whole-body stimuli represented not only a more complex stimuli set, but one intimately linked with the body schema.The mental rotation of the body is of particular importance to embodied cognition theory given that it represents the mental manipulation of the internalized body schema . ResearcWhile it may not always be clear whether older adult difficulties in whole-body mental rotation are due to task complexity or poor body representations, there is evidence that egocentric perspectives are specifically problematic. First, when the mental rotation requires an egocentric perspective (such as rotating a body image by means of one’s own body), older adults show deficits compared to young adults . Second,A subtype of mental imagery is motor imagery, the mental simulation of an action when there are no overt physical actions being made. Motor imagery is arguably a more complex variant of mental imagery for it includes an implicit action plan . Motor iOur understanding of motor imagery has been greatly influenced by Jeannerod, who theorized that covert  actions are neurologically similar to overt motor actions, such that both elicit comparable cortical activation patterns , 2001. IResearch indicates that motor imagery declines are evident in healthy aging . For insPerhaps not surprisingly, there are many similarities between the age-related declines in both mental imagery and motor imagery. Like mental imagery, the aging effect on motor imagery is also affected by both the complexity and perspective of the imagery. Under simple motor imagery conditions, older adults perform equivalent to young adults cf., . HoweverOne specific form of additional complexity for older adults are first-person motor imagery visualizations. Visual dominance of motor imagery in older adults has also been identified in neuroimaging studies. When using motor imagery, both young and older adults engage a network of neural pathways that include visual imagery and motor pathways as well as frontoparietal, subcortical, and cerebellar areas. However, activation intensity and specificity does differ by age group, suggesting that age effects in motor imagery reflect the changes to these brain networks . During Given the age-related decline in mental and motor imagery, it is not surprising that older adults do not benefit from action observation to the same extent as young adults. Aging decreases the efficiency in learning and then executing novel motor sequences  with speOlder adults may rely on visual processing components because their internal action models are degraded . DierschOur review thus far has focused largely on the bottom-up factors  and the mental representations that underlie embodied cognition. We have found that aging affects these systems profoundly, with a common finding of visual prioritization over somatosensory processing in older adults. In cases of multisensory perception, older adult deficits in unisensory processing typically result in gains in multisensory inputs, although visual processing is dominant. A similar tendency toward visual dominance occurs in mental imagery , for visual processing factors dominate the motoric representations in older adults. Thus, basic sensorimotor deficits in older adults result in increased reliance on visual processing over other sensory modalities, and this visual dominance alters the nature of action-based mental representations. We now turn to how bodily action alters perceptual experience, a topic that is central to the embodied cognition framework .A central tenet of embodied cognition is that the mind and the body have reciprocal influence: not only can the mind control and direct the body as traditionally thought, but the body can also direct and influence the mind through its movement, posture, and sensory input. Embodied cognition theorists have long argued that action alters perceptual judgment, and research has confirmed that perceptual judgments of object size and distance correlate with our capacity to act upon the object . This cl2 on the relationship between aging and perceptual capacity, younger and older participants provided slope estimates while looking up from the bottom of variously angled hills. Young adult slope estimates were steeper when placed in physically demanding conditions, a result consistent with the action-specific perception hypothesis. However, older adults provided steeper hill slope estimates than young adults even under typical physical conditions, suggesting that their reduced physiological potential led to perceptual bias. Perceptual scaling tasks have also found that older adults are sensitive to environmental impediments that would complicate walking  walking , essenti walking  and shou walking .What explains this increasing cautiousness in the action-specific perception responses of older adults? While the answer is not yet clear, the action-specific account of visual perception would point to the physical limitations of older adults as determinative to perceptual scaling. If true, the number of potential physiological factors affecting the older adult perception-action relationship may be surprisingly broad. Action-specific perception research has generated a dizzying array of physical factors vulnerable to aging that can influence task performance, including strength , pain leEmbodied cognition argues not merely that the body and bodily action is formative toward cognition and perception, but that the mind itself is unconstrained by the physical boundary of the brain and is extended out into the body in action . AccordiThe study of how tool use is represented in the brain began largely with primate research using single-cell recordings of neuronal sensitivity. Such work has found that when monkeys use tools, the receptive fields of neurons normally coding the spatial extent of the hand became extended into the more distant space of the tool’s reach cf., . An earlStudies with human participants using tools have found similar results of body schema adaption under both behavioral  and neurHow might aging affect the ability to incorporate a tool into the body schema? One source of evidence comes from pantomime studies, in which participants are asked to identify or act out a physical action . In a manner consistent with our earlier review of action observation research, pantomiming research has found that older adults exhibit general declines in pantomiming human actions , especiaWhat might explain older adults’ inability to incorporate tools into the body schema? If we assume that tool use is a complex function with multiple cognitive, sensory, and motor components, age effects at lower sensorimotor levels may disrupt the overt performance of using a tool. After all, tool use requires the smooth integration of visual and tactile inputs, and as already discussed, older adults struggle in MSI-based tasks. There is evidence to this effect. Heuer and colleagues have investigated age-related differences in multisensory processing during tool use with a visuo-motor rotation paradigm. In such tasks, participants look at a display screen while moving a mouse cursor to a target, but vision of the hand movements themselves are hidden under an occluder. On some trials, the cursor pathway is diverted from the actual pathway of the hand movement. After the participants complete their reach and return to the home position, the pathway directions of either the cursor or the hand are displayed. Participants are then asked to modify the displayed pathways to the correct location for the remembered target location. Perhaps not surprisingly, under such conditions older adults commit greater errors than young adults . But morSecondly, tool use is typically performed with the hand, and there is evidence that the cognitive system of older adults is desensitized to their hands. Young adults appear to automatically orient attention toward their hands both immediately prior to and during a reach . Older aOne final factor that may also contribute to older adults’ ability to understand and use tools is the type of knowledge necessary for this complicated task. Effective tool use relies on both semantic knowledge, information connecting the purpose of a tool to a to-be-acted-upon object, and mechanical knowledge, information about the functional allowances of a tool-based on the properties of both the tool itself and the to-be-acted-upon object . AdditioThis review has explored how the framework of embodied cognition can be applied to the study of aging by detailing research falling under three subdomains pertinent to embodied cognition: sensory perception (with a focus on MSI), mental representation (with a focus on motor imagery), and the effect of action on perceptual judgments. Embodied cognition theory predicts that as the body and sensory systems decline, there will be corollary changes in perception and cognition. Older adulthood is a critical period of physical decline, and therefore embodied cognition is a valuable theoretical prism by which to view aging . As we’vWhile aging is associated with a host of physical changes that produce a variety of effects on embodiment, a consistent finding in the literature is that older adults are influenced largely by visual processing over tactile and kinesthetic processing. This visual dominance effect was evident across all three subdomains we covered. Older adults are more heavily influenced by visual processing components during MSI tasks , which mSimilar instances of visual dominance in older adults have been found when performing tasks involving action observation , again aAn important corollary phenomenon is the age-related change in perspective-taking: older adults struggle when visualizing from their own first-person compared to a third-person perspective, displaying an insensitivity for egocentric awareness. This was primarily evident in motor imagery studies which have found decreases in multiple areas: in first as opposed to third person perspectives , in wholIn short, the body’s influence on cognition alters in older adults based on their reliance on visual signals over bodily control. Embodied representations rely on externally originating visual and tactile sensory signals as well as internally originating proprioceptive and vestibular sensory signals. These signals will be weighted differently depending on the task and the quality of the signal. For older adults the internal signals are often degraded – proprioception declines with advanced age , as doesThis scenario would predict that older adults would be most likely to prioritize visual information because it is the most readily available and often the most spatially and temporally precise. However, in cases where vision is not the most reliable modality, vision should follow perception, not lead it. While that is quite difficult to accomplish in healthy older adults, it is found in some clinical populations. For example, bilateral parietal lobe damage  can impair the ability to visually localize and attend to stimuli while leaving these abilities relatively intact in the auditory modality. Note that a similar reliance on visual processing components over somatosensory processing has been identified in older adults suffering from Parkinson’s disease (PD) in order to compensate for their physical declines. Imaging studies have found that older adults with PD not only perform worse on motor imagery tasks, but also show increased brain activity in extrastriate visual areas . The phyM age = 37 years) perform a jigsaw puzzle while working a hand crank. In some trials, the crank rotation matched the expected rotation of the puzzle piece, whereas in other trials the crank rotation was in the opposite direction of the puzzle rotation. When the crank and puzzle rotations matched, performance was improved in the 5- and 8-year-old children, but not the older children or young adults, indicating that motor factors were weighted more heavily early in development. This is consistent with other studies showing that the mental imagery of young children is more heavily influenced by motor processes over visual components  factors. Although it is beyond the purview of this review article, a logical continuation would be to formally develop  an explicit model of how aging alters the manifold factors operative in sensorimotor-cognitive processing. Developing such a model will be a difficult task given the range of potential age-related causal factors. First, there are a host of ‘non-embodied’  cognitive and brain factors that must play a role in how embodiment is altered in aging. As briefly stated in the beginning of this review, older adults exhibit a range of cognitive and brain-based changes. This review has focused almost exclusively on three subdomains pertinent to embodied cognition, but these subdomains are not independent of such factors. Second, social factors are likely operative in the mind-body relationship in aging, although almost no research has been conducted to determine this possibility. This is particularly important considering how negative societal views on aging  might alter performance of the older adults. If an older adult believes that he or she is out of shape or cognitively slow, we can expect that participant performance recorded through most behavioral measures will be affected e.g., . Third, all tasks older adults will favor visual processing. Compensation can take multiple forms depending on the context, and in cases in which the visual inputs are minimized, we would expect that older adults will take advantage of motor factors. Consider We need to be cautious, then, with the concept of an age-related visual dominance. We do not want to say that in We can best understand this age-related change in sensorimotor control as a change to the internal model of older adults. The internal model is the mental calibration of many inputs, resulting in a controlled and purposeful response . BecauseAs we have highlighted throughout the review, virtually every area of aging would benefit from further research using an embodied cognition perspective. Given that, here we will highlight just a few areas of practical importance. One question that has not yet been explored is the age at which changes in embodiment begin to take place. If age-related changes are based on neural dedifferentiation or compensation, then it would be expected that the changes are gradual and positively correlated with age. Relatedly, given that there are individual differences in the onset and rate of neural change with age, there should be corollary individual differences on tasks that tap into embodied effects. Indeed, there is preliminary support for this, with older adults exhibiting wide variability in the relative impact of the body during visuo-motor performance . Not surIt is clear that older adults have altered MSI, and that this impacts not just sensory processing but also higher-level cognition and physical ability. For example, there is a link between MSI and balance, with training on one factor improving performance on the other . Given tEmbodied cognition claims that there is a causal link between physical ability and cognition, so it should not be surprising that studies have found correlations between older adults’ physical capacities and their perceptions e.g., . HoweverThere are many avenues still available for exploration in applying the embodied cognition theoretical framework to understand aging. Indeed, it would appear that we are just scratching the surface of applications to aging, and already we are gaining a richer understanding of age-related declines and the causes of them. The history of gerontological research has focused on isolating and then assessing sensory, cognitive, and physical abilities; it is now more clearly understood that these three systems interact, and that assessing changes means assessing those interactions as well.MC compiled original literature review and wrote primary manuscript. EB contributed to both literature review and manuscript preparation.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Much of human decision making occurs in dynamic situations where decision makers have to control a number of interrelated elements (dynamic systems control). Although in recent years progress has been made toward assessing individual differences in control performance, the cognitive processes underlying exploration and control of dynamic systems are not yet well understood. In this perspectives article we examine the contribution of different approaches to modeling cognition in dynamic systems control, including instance-based learning, heuristic models, complex knowledge-based models and models of causal learning. We conclude that each approach has particular strengths in modeling certain aspects of cognition in dynamic systems control. In particular, Bayesian models of causal learning and hybrid models combining heuristic strategies with reinforcement learning appear to be promising avenues for further work in this field. Handling dynamic systems is a common requirement in everyday life, ranging from operating a novel technical device, to managing a company or understanding the dynamics of social relationships. Considerable progress has been made toward assessing dynamic systems control (DSC) as a cognitive skill, particularly in educational contexts . Howevermicroworlds, which are the focus of the present paper (but see Dynamic systems control can be defined as a form of dynamic decision making that requires (1) a series of interrelated decisions (2) in interaction with a dynamic system inducing states of subjective uncertainty (3) with the aim of attaining (and maintaining) a goal state and/or to explore the system and possible courses of action also see . Subject but see .cognitive model or computational model (of cognition) refer to any mechanistic account of cognitive processes that is sufficiently specified to allow a computer-based implementation yielding quantitative predictions of behavior, cognitive processing steps, or neural activity .We will now consider the contribution of different approaches to modeling cognition in DSC with selected examples. Our brief review begins with comparatively simple and knowledge-lean modeling paradigms, moving toward approaches involving more complex strategies and knowledge structures (see Instance-based learning (IBL) models have arguably been among the most successful approaches to cognitive modeling in DSC. They are based on a simple principle analogous to reinforcement learning: control actions that lead to a successful outcome become reinforced in memory and will therefore more likely be remembered and enacted when a similar situation is encountered in the future . The appA computational IBL model of the sugar factory task has been implemented by An approach similar to IBL was used by Table 1). Furthermore, IBL models cannot easily explain how people acquire explicit knowledge of the causal structure of a system, which is a central element of some DSC tasks . Although incorporating more task-specific knowledge than pure learning models, models of this type typically still have a relatively simple basic structure. When heuristic models are extended with more complex strategies and abstract knowledge structures they gradually transform into complex knowledge-based models, which we will consider next.Complex knowledge-based models involve the creation and transformation of abstract knowledge structures combined with complex cognitive strategies. This corresponds to the notion of mental models guiding reasoning and actions in DSC e.g., . Models A different class of DSC task that requires scientific reasoning to explore the causal structure of unknown systems has been particularly relevant in the recent educationally oriented wave of DSC research . SchoppeAn apparent advantage of complex knowledge-based models is their ability to explain how causal system knowledge combined with reasoning strategies informs the actions that people take. It seems difficult to imagine how some forms of DSC could be explained without recourse to reasoning and abstract knowledge representation, for example, extrapolating system behavior in new situations or hypothesis testing and rule-deduction in discovery learning. However, models of this type are often neither simple nor elegant and require the inclusion of considerable task-specific knowledge .Another modeling approach with a focus on structural knowledge is the use of Bayesian networks to model causal learning . BayesiaFrom a DSC perspective, the strength of Bayesian models of causal learning lies in the nuanced representation of causal structures and probabilistic dependencies combined with a mechanism for updating this knowledge from experience. This makes them a strong contender for explaining structural knowledge acquisition in DSC tasks with an exploration focus e.g., . A BayesTable 1). In terms of knowledge-lean modeling approaches, IBL strikes a good balance between simplicity, cognitive plausibility and explanatory power for a range of DSC tasks. On the downside, IBL has strict task requirements  and cannot easily explain the acquisition of causal knowledge or extrapolation to unfamiliar conditions. Heuristic models have no universal task requirements and can be combined with learning mechanisms to achieve a similar adaptivity as IBL models. However, since effective heuristics rely on exploiting the structure of the environment, finding suitable candidate heuristics for a given task can be a considerable challenge and any specific heuristics-based model is only applicable to a particular niche  could be used as a yardstick for evaluating human performance in DSC see . This stcapacity .In conclusion, computational models of cognition appear to offer a promising path for advancing research and theory development in DSC. Computational approaches have successfully been used to model a range of cognitive phenomena in different domains of DSC. Promising starting points for further developments include, for example, recent advances in causal learning and hybrid models which combine simple heuristics with reinforcement learning mechanisms. Computational modeling of cognitive processes in DSC remains a constructive challenge that probes – and ideally enhances – our understanding of human behavior in complex dynamic environments.Both authors contributed to writing the manuscript and approved it for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Frailty is an aggregate expression of susceptibility to poor outcomes, owing to age-, and disease-related deficits that accumulate within multiple domains. Older patients who are frail before surgery are at an increased risk of morbidity and mortality, and use a disproportionately high amount of healthcare resources. While frailty is now a well-established risk factor for adverse postoperative outcomes, the perioperative literature lacks studies that: 1) compare the predictive accuracy of different frailty instruments; 2) consider the impact of frailty on patient-reported outcome measures; and 3) consider the acceptability and feasibility of using frailty instruments in clinical practice.We will conduct a multicenter prospective cohort study comparing the predictive accuracy of the modified Fried Index (mFI) with the Clinical Frailty Scale (CFS) among consenting patients aged 65 years and older having elective major non-cardiac surgery. The primary outcome will be disability free survival at 90 days after surgery, a patient-reported outcome measure. Secondary outcomes will include complications, length of stay, discharge disposition, readmission and total health system costs. We will compare the accuracy of frailty instruments using the relative true positive rate and relative false positive rate. These measures can be interpreted as the relative difference in the probability of one instrument identifying a true case of death or new disability compared to another instrument, or the relative difference in the probability of one instrument identifying a false case of death or new disability, respectively. We will also assess the acceptability and feasibility of each instrument.Frailty is an important prognostic factor in the growing population of older patients having surgery. This study will provide novel findings regarding the choice of an accurate, clinically useable frailty instrument in predicting patient reported outcomes, as well as morbidity, mortality and resource use. These findings will inform current practice and future research. Frailty is an aggregate expression of susceptibility to poor outcomes, that is due to age-related and disease-related deficits  which acPatients 65 years of age and older comprise an ever-increasing proportion of the surgical population . On its Identifying frail patients prior to surgery could improve the care and outcomes of older patients through a variety of mechanisms: identification of high risk patients can lead to improved decision making and informed procedural consent , while tNumerous frailty instruments exist to identify or diagnose individuals as frail . AlthougFinally, despite recent recommendations from a variety of national speciality societies that frailty be a routine part of preoperative assessment in older patients , 24, theBased on the knowledge gaps described above, the objectives of this prospective cohort study are to 1) compare the accuracy of the modified Fried Index  (CFS) inWe will conduct a prospective, multi-center cohort study at a multi-site academic health sciences center ), and a community-practice focussed single site hospital . TOH is a 900-bed tertiary care center that is the regional referral center for trauma, vascular, neuro, thoracic and complex oncology surgery, and serves a catchment population of 1.2 million people. Hôpital Montfort is a 300-bed hospital with a community-focussed practice and serves a predominantly French-speaking population. Both hospitals are located in Ottawa, Canada. All patients will be recruited in the preoperative assessment unit of each hospital, where patients are seen by a registered nurse or physician anesthesiologist for medical assessment prior to surgery. Research ethics board (REB) approval has been granted by each study center.Individuals aged 65 years or older on the day of their elective, major non-cardiac surgery will be eligible to participate. Major non-cardiac surgery will be defined as surgery not involving the heart, pericardium, or cardiopulmonary bypass with an expected length of stay of at least 2 days, and will be limited to primary procedures .included. Because some frail patients may be cognitively impaired, REB approval includes the ability for informed study consent from a patient’s health decision maker. However, patients unable to answer outcome scales will be excluded. No other specific exclusion criteria will be applied.All consenting patients having an eligible procedure who are able to communicate in English or French, and who are able to be contacted by telephone for follow up will be Our primary exposure of interest is the presence and severity of frailty as measured by two existing frailty instruments with evidence of predictive utility and feasibility in the acute care setting. The mFI  is a 5-pAnalysis section).Frailty will be defined by typically used cut-offs for the mFI (≥3) and CFS (≥4), however, various alternative forms that account for the degree of frailty will also be tested  at 90 days after surgery, measured as a binary indicator of being alive with a disability score of 25% or less, based on the 12-item World Health Organization Disability Assessment Schedule 2.0 (WHODAS) . For peoInternational Classification of Diseases Tenth Edition codes grouped by patient safety indicator clusters using Type 2 diagnoses [Secondary outcomes will include complications (defined by Post-Operative Morbidity Survey  criteriaiagnoses ), hospitiagnoses ), dischaBaseline clinical and demographic characteristics collected will include data reported by patients or personal support members/caregivers: age, gender, cognitive status (using the AD8 questionnaire ), depresThe acceptability of each frailty instrument to clinicians and patients will be assessed using Likert scale scored questions based on relevant queries from previously validated acceptability scales . We willPatient and clinical characteristics will be compared across frail and non-frail strata using descriptive statistics.Our primary analysis will calculate the predictive accuracy of each of the CFS and the mFI in identifying patients who develop a new disability or die in the 90 days after surgery using concepts from diagnostic accuracy testing. Specifically, we will compare the true positive rate , as well as the false positive rate  between instruments. The true positive rate reflects the benefit of screening for adverse outcome risk using a particular instrument by quantifying the proportion of people who will actually experience the adverse outcome and who are identified by the instrument. Alternatively, the false positive rate reflects the disadvantage of using the instrument by quantifying the proportion of people who are erroneously identified as likely to experience an adverse outcome . We willTo compare the accuracy of the two frailty instruments head to head we will use the relative true positive rate (rTPR), and relative false positive rate (rFPR) with 95% confidence intervals . The rTPWe will also perform subgroup analyses in pertinent procedural cohorts, including total joint arthroplasty, intra-abdominal surgery, oncology, and vascular surgery. In each subgroup, a separate rTPR, rFPR and associated 95% CIs will be calculated.In addition to the dichotomized definition of frailty used in our primary analysis, both the mFI and CFS provide an ordinal frailty scale. Therefore, to assess the discriminatory performance of each frailty scale expressed on an ordinal basis, we will perform a receiver operator characteristic (ROC) curve analysis to identify whether a different optimal cut-point may exist for each frailty instrument in the perioperative setting . If a cuWe will also measure the strength of association between frailty and primary and secondary study outcomes using regression coefficients and 95% confidence intervals from an appropriate model: for dichotomous outcomes we will calculate the odds ratio using logistic regression, for length of stay (time to discharge) we will calculate the hazard ratio using Cox proportional hazards regression, for hospital and health system costs we will use relative difference from generalized linear regression.In addition to frailty, the ACS/AGS Optimal Preoperative Assessment of the Geriatric Surgical Patient recommends assessment of a variety of patient conditions and characteristics . TherefoWe will measure the acceptability of each instrument for clinicians by reporting the mean and standard deviation of each acceptability question for each tool, as well as an aggregate mean and standard deviation across questions. For patients, we will calculate the mean and standard deviation for each instrument in relation to the perceived of ease of use, and whether the patient would be willing to complete the instrument again in the future.We will measure the feasibility of each instrument by expressing the mean number of missing items from each frailty instrument. We will also calculate the mean time in seconds that were required to complete each instrument.The sample size calculation is based on the primary objective of comparing the mFI (≥3) and CFS (≥4) with respect to their accuracy in identifying patients with events at 90 days after surgery. We used the sample size calculation approach described by Alonzo et al. for paired comparisons of diagnostic test accuracy . The appThis multicenter prospective cohort study will address multiple knowledge gaps in the perioperative frailty evidence base. We will describe the comparative performance of two leading frailty instruments in predicting a patient reported outcome measure (DFS), as well as commonly reported postoperative outcomes. Furthermore, we will assess the predictive value of two frailty instruments in addition to known preoperative risk factors. Finally, we will provide new information regarding the acceptability and feasibility of the mFI and CFS, which in addition to their predictive accuracy, should guide clinicians in choosing an appropriate instrument with which to perform preoperative frailty assessments.Given the rapid aging of Western populations , 51, andFeasibility and acceptability are known external barriers to practice change . Althoug


Among the questions discussed were: how well do models represent the different stages of human disease; how can we model the involvement of the human immune system and microenvironment in breast cancer; what are the appropriate models of metastatic disease; can we use models to carry out preclinical drug trials and identify pathways responsible for drug resistance; and what are the limitations of patient-derived xenograft models? We briefly outline the areas where the existing breast cancer models require improvement in light of the increased understanding of the disease process, reflecting the drive towards more personalised therapies and identification of mechanisms of drug resistance.Research using animal model systems has been instrumental in delivering improved therapies for breast cancer, as well as in generating new insights into the mechanisms that underpin development of the disease. A large number of different models are now available, reflecting different types and stages of the disease; choosing which one to use depends on the specific research question(s) to be investigated. Based on presentations and discussions from leading experts who attended a recent workshop focused on  Summary: This Review provides a summary of the many varied uses of mouse models in breast cancer research focusing on their strengths, challenges and future directions. Nonetheless, breast cancer remains the leading cause of cancer-related female death worldwide with more than half a million women succumbing to the disease annually . One of the reasons for this is that breast cancer is not a single disease entity ], there is no cure currently available for metastatic breast cancer, which affects an estimated 40% of UK patients (breastcancernow.org) and likely accounts for the decline in survival rate to 65% at 20 years post-diagnosis. Genetic sequencing endeavours have identified many of the mutations implicated in breast cancer ; a novel resource funded by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) to create a secure, searchable database of archived material derived from in vivo breast cancer models, which is available to share between researchers , established from partners in 10 different European countries covering 16 academic institutions, is a network of cancer scientists and clinicians who have pioneered the standardisation of PDX models as clinically relevant models of human cancer. EurOPDX has created an extensive virtual collection of PDX models (>1500) encompassing many cancer types that have been genomically and histologically characterised in well-established laboratories. The aim of the consortia is to unify and harmonise the use of PDX models, which could lead to better resources for investigating predictive biomarkers and testing novel therapeutic approaches, and ultimately, personalised cancer treatment.in vivo models has been the increasing understanding of the many different subtypes of breast cancer  and triple negative  – have been extensively studied, not all can be established in vivo  do metastasize in syngeneic models (involving transplant of mouse-derived cells to an independent strain-matched mouse), although these are currently a limited resource . OtherwiPatient-derived xenografts (PDXs) – involving the transplantation of primary human cancer cells or tumour pieces into host mice – were developed to address the shortcomings of CDX, heralding hope for models with improved clinical relevance. Although transplantation of human tumour fragments into immunocompromised mice has a long history  directly into the mouse ductal epithelium rather than the fat pad  pathway activation and outgrowth of stem cell populations, have been found during acquired resistance to anti-oestrogen therapies  considering that less-aggressive cancers may not respond in the same way to therapy as those which are more proliferative and/or have different molecular alterations. Finally, the study of the tumour microenvironment is compromised both by intrinsic species differences (e.g. mouse fat pad) and the lack of immune cells in tolerant hosts. This latter point is notable considering the impact of immune-based therapies in the clinic , compared with the time taken to establish a PDX and using it to test the response to different therapeutic regimens (months to years), so currently the potential of these models is limited to cohort-based preclinical studies. Regardless of these limitations, the wide acceptance of PDX models in the pharmaceutical industry is worthy of mention. There has been an explosion in the commercial sector in the use and availability of PDXs as the model of choice for translational research. Companies such as Champions Oncology and Crown Biosciences offer partnerships to run preclinical drug trials, while certain suppliers such as Horizon Discovery and The Jackson Laboratories make these models available to academic institutions. This is a fast-moving field and efforts are now being honed into producing humanised systems (see below).For addressing early events in the tumour process, genetically engineered mouse models (GEMMs) come into their own. In these models, spontaneous tumour initiation occurs within the correct microenvironment from an otherwise normal mammary cell. These may be simple oncogenic-driven transgenic mice, referred to here as conventional GEMM (e.g. MMTV-PyMT). One limitation to the conventional GEMM models is that not only are the regulatory sequences used to drive transgene expression not well-defined in terms of specific lineage/expression domains, but also, the specific oncogenes may not necessarily reflect those observed in human tumours. Nonetheless, these models continue to serve a purpose in breast cancer research .Blg-Cre;fl/fl;p53fl/flBrca1). These conditional GEMMs use the Cre/loxP system in which a tissue-specific promoter drives expression of the bacterial enzyme Cre recombinase (e.g. Blg-Cre) within the mammary gland to elicit recombination of DNA between loxP sites (e.g. introduced into the coding region of tumour suppressors such as p53 and Brca1). Lists of the many different breast cancer GEMMs  can be found in other recent reviews  can demonstrate phenotypic similarities as well as disparities -Cre or keratin 5 promoter (Krt5)-Cre have been used to direct oncogenic events to the basal lineage; whey acidic protein promoter (Wap)-Cre and keratin 8 (Krt8)-Cre to target luminal cells, and β-lactoglobulin (Blg)-Cre and Cited1-Cre to specifically target ER− and ER+ luminal cells, respectively. However, despite the use of lineage-specific promoters, a complete characterisation in the expression pattern of these Cre recombinases has not been done, and so ‘off-target’ and/or unexpected expression can confound studies. For example, Krt14-Cre can be active in the luminal as well as basal lineages -deficient breast cancers originated from luminal progenitors, contrary to the expectation that these were of basal stem cell origin , a common genetic driver of breast cancer, invokes mixed-lineage tumours even when expressed in unipotent progenitor cells, demonstrating plasticity .The use of lineage-restricted GEMMs has been instrumental in studies to identify the cell of tumour origin . A primel origin . Howevern models . Studyinasticity  as well in vivo and have the advantage that pathway inactivation can be achieved either genetically and/or pharmacologically. For example, deregulation of cell cycle control  and its downstream effector MAD2L2 , led to rescue of homologous recombination in BRCA1-deficient cells through reinstatement of double-strand-break signalling  show manifestation of spontaneously arising metastatic disease in lymph nodes and lungs. These models have been, and continue to be, used to study metastatic disease (Tgfb1) and β1-integrin (Itgb1) are important in metastasis  and the realisation that cells could be genetically engineered to express this without detrimental effects , enablinpulation .in vivo imaging following injection of the substrate luciferin in animals bearing tumour cells genetically engineered to express firefly luciferase   . Initiale animal . For exae animal  and stroe animal  have beeeal time .Although not widely available, a range of quantitative functional imaging capabilities, e.g. PET (positron emission tomography)/CT, SPECT (single photon emission computed tomography)/CT and PET/MRI (magnetic resonance imaging) are being adapted for preclinical research, leading to increased understanding of tumour development and effects of therapy . FurtherloxP system, described above) circumventing lethal and off-target effects elicited by germline deletion of fundamental genes -based knockdown as a means to investigate loss of specific tumour suppressor genes without the need for protracted breeding programmes . Some groups have expedited this process by targeting new alleles in embryonic stem cells derived from pre-existing GEMMs (GEMM-ESCs), an approach that shows excellent potential for streamlined and high-throughput studies . Others ogrammes .in vivo tumourigenesis models. High-throughput approaches – such as those using GEMM-ESCs and shRNA – will be necessary if biological verifications of new genes are to match the speed of these discoveries. A recent report, describing how the CRISPR/Cas9 gene-editing system could be combined with GEMM to provide in vivo validation of a candidate tumour suppressor in invasive lobular breast cancer demonstrates a powerful new system for the elucidation of functional relevance in the context of mammary carcinomas , which prohibits application in Cre/loxP-driven tumour models. Therefore, syngeneic tumour implants or conventional transgenic tumour models  are used rather than more physiologically relevant GEMMs. As stromal influences are likely to impact differently on subtypes of breast cancer (Frt), which would permit investigation with the many available Cre/loxP GEMMs.The importance of the microenvironment in tumour evolution is undisputed . For exaroblasts  or E2f3 rophages  modifiest cancer , it is it cancer  to direcin vivo models more clinically relevant, researchers have incorporated cells and tissues to increase the human component of the tumour microenvironment i.e. to humanise models. Examples are the implantation of human bone pieces . Indeed, humanised mice in which triple-negative breast cancer PDX responds to immunotherapy are now commercially available. The high cost of these animals is likely to present a barrier to their general uptake, but they represent an important step forward in terms of our ability to investigate the potential utility of immunotherapies in breast cancer.Recently, the Jackson Laboratories described humanised PDX models as the next ‘big thing’ in cancer modelling (in vivo is most often quite rapid (progressing within weeks), in contrast to the longer latency of human disease (involving years and even decades). In this respect, model systems do not represent the clinical reality; however, it is notoriously difficult to work with slow-growing models because results need to be delivered within the normal funding cycle or within the duration of a standard PhD project (3-5 years). As discussed in the workshop, the realisation that ‘slow is better’ is often balanced against the need to know whether a specific genetic or therapeutic manipulation works in a model whilst sufficient time is still left on a particular grant. It was agreed that science funding bodies generally support the use of short-term (and therefore less representative) models, rather than accepting a more limited  output from models where it may take 1-2 years before tumours develop. Many of the workshop participants are members of scientific committees that make decisions on which projects to fund, so there are opportunities to influence thinking in this area with the aim of providing the longer-term funding required to implement the use of more clinically relevant model systems.A particular challenge for researchers is that breast tumour growth in vivo model systems is expensive, requires expert staff and facilities, and can be time-consuming, presenting a barrier for many researchers. In addition, translation of basic findings into patient benefit requires evidence to be obtained from several model systems. Paradoxically, those who routinely use in vivo models are almost always generating more material than they need for the purpose of testing the original hypothesis. The SEARCHBreast initiative  . Model sBRCA1 disease has been achieved predominantly through allelic deletions, but these are not truly representative of the patient-derived pathogenic mutant alleles. The importance of this was recently demonstrated: different Brca1 mutations elicited similar disease patterns but showed differences in therapeutic response and resistance mechanisms (As for other models, it was interesting to see one described recently for inflammatory breast cancer, a rare but very aggressive type of breast cancer , but thechanisms , 2016. MIn vivo models of breast cancer have proven their usefulness in many different contexts and will continue to contribute to our understanding of disease progression, therapeutic response and resistance mechanisms. The field has progressed incredibly in the last 20-30 years and is likely to evolve further with technological advances that enhance the growing arsenal with which researchers can probe unanswered questions. Nonetheless, scientists need to consider the limitations of each model and choose the one that best represents the process they aim to model and addresses their specific research question. New models being developed using patient-derived tumour material have shown promise, but sharing of these resources is very important to allow comparison between studies and make them widely available to the research community. Meanwhile, new and improved models for metastasis and study of the microenvironment are urgently required. In sum, although no perfect in vivo model of human breast cancer will ever exist, such models remain valuable research tools complemented by clinical material, ex vivo and in vitro systems, and we are equipped with the knowledge and technologies to continue improving them.


Huntington's disease (HD) is a neurodegenerative disease that offers an excellent paradigm for cell replacement therapy because of the associated relatively focal cell loss in the striatum. The predominant cells lost in this condition are striatal medium spiny neurons (MSNs). Transplantation of developing MSNs taken from the fetal brain has provided proof of concept that donor MSNs can survive, integrate and bring about a degree of functional recovery in both pre-clinical studies and in a limited number of clinical trials. The scarcity of human fetal tissue, and the logistics of coordinating collection and dissection of tissue with neurosurgical procedures makes the use of fetal tissue for this purpose both complex and limiting. Alternative donor cell sources which are expandable in culture prior to transplantation are currently being sought. Two potential donor cell sources which have received most attention recently are embryonic stem (ES) cells and adult induced pluripotent stem (iPS) cells, both of which can be directed to MSN-like fates, although achieving a genuine MSN fate has proven to be difficult. All potential donor sources have challenges in terms of their clinical application for regenerative medicine, and thus it is important to continue exploring a wide variety of expandable cells. In this review we discuss two less well-reported potential donor cell sources; embryonic germ (EG) cells and fetal neural precursors (FNPs), both are which are fetal-derived and have some properties that could make them useful for regenerative medicine applications. •Cell replacement therapy for neurodegenerative disease.•The shortage of primary human fetal tissue that necessitates the search for alternatives.•Potential of fetal derived neural precursor cells.•What about embryonic germ cells? This mawhole ganglionic eminence (WGE) in the fetal brain  . Transplin vitro and stored to facilitate GMP (Good Manufacturing Practice) production, whilst maintaining the capability to generate striatal MSNs.For the longer term, however, it will be necessary to identify expandable sources of donor cells for clinical application, as primary fetal cells present several challenges: they are scarce ; they cannot be stored long-term ; and they are difficult to standardise. Thus, in addition to continuing primary fetal transplants for the reasons outlined above, it is also important to identify cells that can be expanded in number Expandable sources of cells, including human embryonic stem (ES) and human adult-derived induced pluripotent stem (iPS) cells, which can be directed down neural lineages and specified to the required cell type are reviewed extensively elsewhere . Here we2In vivo, PGCs are unipotent and destined to give rise exclusively to gametes, however, in vitro exposure of mouse PGCs to exogenous fibroblast growth factor (FGF) 2, leukaemia inhibitory factor (LIF) and stem cell factor (SCF) can cause conversion to EG cells, which proliferate rapidly and form colonies similar to those observed when culturing ES cells  that reside in the gonadal ridge of first trimester embryos. PGCs are induced from pluripotent epiblast cells very early in embryonic development , and conES cells . EG cellES cells . So far,ES cells . HoweverES cells . AlthougES cells .South Wales Initiative for Transplantation (SWIFT) program in accordance with the Polkinghorne and Department of Health guidelines, with full ethical committee approval, and under the Cardiff University Human Tissue Act 2004 research licence  and eitnd human . We alsond human ; GDNF, fnd human ; EGF, whnd human ; and thend human . None of•High dose (100 ng/ml) SCF supplementation, added to either StemPro 34 medium or standard medium containing 15% fetal calf serum (FCS), as this has been reported to promote colony formation of germ cells in mixed fetal gonadal cultures grown without feeder cells (er cells . We obseer cells F. With c•Various feeder layers. The STO mouse embryonic fibroblasts cell line (ATCC CRL-1503) has been reported as the most successful cell line for this purpose  using the pluripotency marker CD133, which is expressed in the germline  culture of PGCs, we were unable to generate any hEG cell lines. We did, however, observe an effect of high SCF concentrations on human PGC adhesion and migration, which could lead to future tools for isolating this highly vulnerable cell type. It seems likely that the factors which can induce de-differentiation of mouse PGCs to a pluripotent state are not sufficient for the human equivalent. This is congruent with the fact that no long-term expandable hEG cell lines have become available to researchers, despite their generation first being reported in 1998 . Fundame3It has long been known that proliferative cells with the capacity to differentiate into cells of a neural lineage (FNPs) can be isolated from the developing fetal WGE, and other brain regions. This was initially shown in rodents  and sincin vitro produce fewer MSN-like neurons and survive poorly following transplantation into rodent HD models  expanded WGE-derived hFNPs retain the ability to survive and integrate into the host brain . This stE grafts . This daE grafts , but to E grafts  and may In a comparison of hFNP and hWGE grafts 20 weeks post-transplantation, graft-derived DARPP32 positive cells (a classic marker of MSNs) were seen both in primary WGE and expanded WGE grafts , and steTo date, there is very limited literature reporting on functional assessments of hFNP grafts in HD models. McBride et al in 2004 reported improved functional effect on the cylinder task following transplantation of human cortical derived FNPs in the quinolinic acid lesion model of HD . Howeverin vitro, and also that they are capable of projecting to target specific brain regions. It is important to acknowledge that most studies to date, including the ones presented here, have relied on default neuronal differentiation of the transplanted FNPs post-transplantation. That is, FNPs are precursor cells, and in these experiments they have not undergone directed differentiation towards specific neuronal phenotypes. An important next step will be to subject FNPs to molecules known to be important for MSN differentiation.In summary, there is some evidence that hFNPs retain the ability to default to an MSN-like phenotype following modest expansion 4In conclusion, we review the potential of two major sources of fetal-derived stem cells as donor cells for regenerative medicine in HD. At this stage in the development of CNS regenerative medicine it is important to properly consider all possible donor cell sources, as there are factors associated with each that make them more or less suitable for individual conditions. For example, another strategy is the use of fetal-derived iPSCs, on the basis that they may possess a different range of properties to adult-derived iPSCs, but there is currently very little literature in this area. Here we discuss our extensive attempts to produce hEG cells, which we were unable to convincingly generate and maintain, and this is consistent with the small numbers of reports of successful conversion in the literature. Further exploration of this cell type will need to await a better understanding of the biology of hPGCs. In contrast, we suggest that FNPs hold more promise. Although they cannot as yet be regarded as potential donor cells for neural transplantation, we suggest that there is sufficient positive data to support further exploration of their potential.


In an effort to develop more effective therapy for tuberculosis (TB), research efforts are looking toward host-directed therapy, reprograming the body’s natural defenses to better control the infection. While significant progress is being made, the efforts are limited by lack of understanding of the pathology and pathogenesis of adult type TB disease. We have recently published evidence that the developing lesions in human lungs are focal endogenous lipid pneumonia that constitutes a region of local susceptibility in a person with strong systemic immunity. Since most such lesions regress spontaneously, the ability to study them directly with immunohistochemistry provides means to investigate why some progress to clinical disease while others asymptomatically regress. Furthermore, this should enable us to develop more effective host-directed therapies. Morphoproteomics has proven to be an effective means of characterizing protein expression that can be used to identify metabolic pathways, which can lead to more effective therapies. The purpose of this perspective will argue that using morphoproteomics on human TB lung tissue is a particularly promising method to direct selection of host-directed therapeutics. Mycobacterium tuberculosis (MTB) on the host but also various immune mechanisms in response to bacterial antigens. TB disease is a chronic infection in immune competent hosts, displaying different pathologies, often simultaneously, in microenvironments in the same infected tissue, mostly in the lung (Progression of pulmonary tuberculosis (TB) in adults is a rare phenomenon in that at least 90% of cases regress spontaneously without producing clinical disease. Very little is known of why and how infection progresses to clinical disease in some people despite spontaneously regression in most. What is known is that TB disease is multifaceted, involving not just the actions of the pathogen the lung –3. Protethe lung –6, and oThere is no question that host immune responses play crucial roles in disease progression and transmission, but currently no therapeutic has been developed to suppress the immune induced pathology. Such host-directed therapy is routinely used and invested heavily in research in cancer –12, autoin vitro and in vivo models to tease apart mechanistic parameters of diseases may be useful but may not adequately represent the human disease. Thus, targets identified through TB models may not be effective in the human patient. The best method to select effective targets for host-directed therapy for TB disease is by studying the human patient.Host-directed therapy targets pathological mechanisms, either by shutting down pathways or manipulating immune responses to improve protection against the MTB pathogen. Proper identification of these pathological targets is crucial for the effectiveness of any host-directed therapy. Many pathological mechanisms of TB overlap with other immune-based diseases, providing TB researchers with a vast foundation of commercially available drugs  that havMycobacterium tuberculosis is an obligate human pathogen since only humans develop cavities able to expel large numbers of organisms into the environment to infect new hosts  and correlative expressions” . The metin vitro and/or animal models do occur in the human disease but also to demonstrate that the selected target(s) will affect critical pathology. From our extensive studies of human TB pathology, we hypothesize that foamy alveolar macrophages (obstructive lipid pneumonia) are the critical pathology directly responsible for the development of cavities , the putative downstream effector of mTORC2 , leading to necrosis of the MTB-infected cell and MTB escape and spread of infection , 60. How T cells . Upregul T cells , leading T cells , suggests Figure .In cancer studies, expression of COX-2 is associated with increase in T regulatory cells . T regulAdditional lung samples are currently undergoing the same morphoproteomic analysis. At the time of this manuscript preparation, four additional human TB lung samples have demonstrated the same pattern of mTOR and COX-2 staining in the alveolar macrophage pathological microenvironments (Hwang observations). With both mTOR and COX-2 mechanisms are potentially highly active in TB lungs, it seems logical to argue that designing host-directed therapy that would target both pathological pathways should offer the most success. There are several FDA-approved drugs that target mTOR and COX-2. Using commercially available products will enable clinical testing of the proposed therapy once proof-of-concept is established in appropriate animal models. We have identified two inhibitors that may offer the most effective outcome in reversing MTB-induced host pathological responses.In vitro analysis showed that Metformin directly reduced phosphorylation of mTOR and p70S6k, increasing apoptosis  and/or host immune cell surface/secreted proteins , 74–77. in vitro and/or animal models. Our approach is unique in that morphoproteomics directly analyzes pathological mechanisms in human tissue, allowing selection of targets for therapy that have been proven to be correlated with human disease. Additionally, morphoproteomics can also be used to tailor host-directed therapy to the individual patient, as it has been applied in cancer patients (We offer the promise of an alternative strategy to developing new treatments for TB beyond just searching for effective antibiotics or choosing host-directed therapeutic targets from patients , 34, 45,S-AH prepared the manuscript and did the final data analysis. RB performed the morphoproteomic analysis and help edit the manuscript. RH provided the pathology analysis and edit the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer IO and handling Editor declared their shared affiliation, and the handling Editor states that the process nevertheless met the standards of a fair and objective review.


Plants have evolved a variety of defense mechanisms to tackle virus attack. Endogenous plant proteins can function as virus suppressors. Different types of proteins mediate defense responses against plant viruses. Pathogenesis-related (PR) proteins are activated upon pathogen infections or in different stress situations and their production is one of many components in plant defense. Ribosome-inactivating proteins (RIPs) suppress translation by enzymatically damaging ribosomes and they have been found to have antiviral activity. RNA-binding proteins (RBPs) bind to target RNAs via specialized RNA-binding domain and can directly or indirectly function in plant defense system against RNA viruses. Proteins involved in silencing machinery, namely Dicer-like (DCL) proteins, Argonaute (AGO) proteins, and RNA-dependent RNA polymerases (RDRs) confer innate antiviral defense in plants as they are able to degrade foreign RNA of viral origin. This review aims to provide a comprehensive and up-to-date picture of plant proteins participating in antiviral defense. As a result we discuss proteins conferring plant antiviral resistance and their potential future applications in different fields of life including agriculture and medicine. Plants possess a wide spectrum of defenses to deal with virus infections. They have inducible defense systems which are activated upon virus attack. The reaction to virus infection, among other elements, usually involves the production of different plant proteins which prevent further spreading of the virus. Pathogenesis-related (PR) proteins are activated in plants under pathological or similar circumstances, such as pathogen attack, wounding or exposure to particular plant hormones, salinity, cold, drought, etc. The production of PR proteins in the uninfected parts of affected plants can cease further virus infection. Antimicrobial peptides (AMPs) were found to have antiviral activities in vitro and they are considered as potential antiviral agents with possible biotechnological applications. Other plant proteins were also found to have antiviral properties in vitro. Such activity is characteristic for ribosome-inactivating proteins (RIPs), RNA-binding proteins (RBPs), and some defense-related proteins. Another way to tackle virus attack is RNA silencing which functions as a basic antiviral immune system in plants. Proteins playing a central role in the antiviral RNA silencing pathway include Argonautes (AGOs), RNA-dependent RNA polymerases (RDRs), and members of the plant Dicer-like (DCL) protein family. All these proteins are either presumed to be involved in defense responses of plants against viral infections or have been shown to possess antiviral activity in vitro which could be potentially utilized in agroeconomics. Nevertheless, mechanism of antiviral activity of plant proteins is still not fully understood. It is known that they can interact with viruses directly, occupy the virus infection site, inhibit the synthesis of virus protein and genome, or indirectly activate plant defense systems, thus enhancing resistance to viruses. In this review we have focused primarily on PR proteins, RIPs, RBPs, and proteins participating in RNA silencing as they are the main components of plant defense against viruses. The main premise behind writing this review was not only to summarize current knowledge regarding plant antiviral proteins but also to distinguish and discuss three classes of antiviral proteins—those which are a part of innate or induced defense response of plants to protect them against viral infection and those which are produced or cloned in other plants and exert antiviral effects against a wide range of plant and also animal viruses . We distR-gene products have leucine-rich repeat (LRR) domains coupled to a putative nucleotide binding site (NBS) domain. Recognition between corresponding plant R protein and pathogen Avr proteins induces effector-triggered immunity (ETI) (previously named gene-for-gene resistance) . Furthermore, the development of trichosanthin-based immunotoxins, such as the one by Wang and colleagues [It is important to realize that antiviral activity of plant proteins observed with the use of different strategies is not always comparable, because each of these strategies answers different questions. As a good example serve proteins which were purified and then examined in different antiviral assays. It is confirmed that such proteins are antiviral in vitro but whether or not they act in a similar way and have similar properties in their natural state in plants remains unknown. However, in vitro experiments provide some additional insights into the potential application of plant antiviral proteins. On the other hand in vivo methods such as “gene knockout technology” give us clearer views on what the antiviral function of proteins in plants is and help to identify proteins contributing to plant innate or induced antiviral defense. Nonetheless, all types of experiments need to be performed to obtain a better picture of protein function and its possible applications. For example, from practical point of view RIPs can be used to enhance plant defense against viruses and potentially other parasites. In consequence, the use of properly mutated less toxic type 1 RIPs may be less severe to transformed plants, causing less damage. Transgenic plants expressing RIPs have been exploited in agriculture to boost immunity and protect crops from viruses while minimizing the application of potentially dangerous plant protection products ,146. Whelleagues , may resRNA silencing-mediated approach to fight virus infections has become a powerful tool in resistant crop production. Transgenization with long hairpin RNA (hpRNA) and with artificial miRNA have been reported to provide resistance against plant RNA viruses ,153,154.Continued research on plant antiviral proteins will undoubtedly provide novel insights into their mechanisms of action and can potentially facilitate the development of new biotechnological tools to improve general crop yield and quality in agriculture. It is essential to better understand the mechanism of action of antiviral proteins to take advantage of their properties in different areas of life. These proteins may be used to develop transgenic plants that could express antiviral proteins at high levels in the presence of the pathogen, what could possibly enhance plant resistance to virus infections, reducing the loss in crops, and also decreasing the need for pesticide application.


Wound healing is a primary survival mechanism that is largely taken for granted. The literature includes relatively little information about disturbed wound healing, and there is no acceptable classification describing wound healing process in the oral region. Wound healing comprises a sequence of complex biological processes. All tissues follow an essentially identical pattern to complete the healing process with minimal scar formation. The oral cavity is a remarkable environment in which wound healing occurs in warm oral fluid containing millions of microorganisms. The present review provides a basic overview of the wound healing process and with a discussion of the local and general factors that play roles in achieving efficient would healing. Results of oral cavity wound healing can vary from a clinically healed wound without scar formation and with histologically normal connective tissue under epithelial cells to extreme forms of trismus caused by fibrosis. Many local and general factors affect oral wound healing, and an improved understanding of these factors will help to address issues that lead to poor oral wound healing. In Greek mythology, the Rod of Asclepius is a serpent-entwined rod wielded by the Greek god Asclepius. Wounded patients could be healed if they were brought to the temple and the serpent licked their wounds during the night Gardner, . The RodWound healing entails a sequence of complex biological processes  occurs without callus formation, given the presence of a good blood supply and an existing stable fixation without mobility of the bone fragments—which must be in direct contact with each other with a fracture gap of up to 1 mm  is characterized by callus formation, and is by far the most important form of bone healing in maxillo-facial surgery  or tooth transplantation, a special form of local ischemia can arise in which neovascularization occurs through an open apex, and is followed by osteodentin deposition with a small central pulpal channel that contains a blood supply—termed root canal obliteration. This predominantly occurs in teeth with an open apex, within the first year after trauma. The role of odontoblasts in this process remains unclear  and polyglyconate (Maxon) being the least reactive, to polyglycolic acid (PGA) and polyglactin acid (Vicryl) showing mid-level reactivity, to chromic catgut as the most reactive with tissues (Hollander and Singer, In cell cultures and laboratory animals, local anesthetics exhibit an inhibitory effect on wound healing, which is mainly reflected in the inflammatory and proliferation phase of wound healing (Brower and Johnson, Although, age has been proposed to be a cause of bad wound healing, this is not supported by evidence (Karamanos et al., Obesity is considered to be a general factor contributing to disturbed wound healing (Guo and Dipietro, In the literature, Ehlers-Danlos syndrome and Marfan syndrome are stated to be associated with bad wound healing (Cohen et al., Macrophage numbers increase with vitamin A intake. A lack of macrophages leads to reduced collagen synthesis and inhibits wound healing.Corticosteroids have an inhibitory effect on macrophages, leading to a decline in collagen synthesis. Acute administration of high doses of corticosteroids should not impair wound healing, as opposed to chronic corticosteroid administration (Wang et al., Several epidemiological studies report that conditions related to chronic inflammation can be improved by a diet rich in bioactive fat mediators—as present in fish oil, e.g., poly unsaturated fatty acids, eicosapentaenoic acid and docosahexaenoic acid—together with low-dose aspirin (McDaniel et al., Undernutrition is a problem in wound healing, as is established in daily practice among some patients with mouth cancer combined with ethanol abuse Figure , and in Diabetes mellitus can severely disturb wound healing, likely due to toxic sorbitol accumulation in tissues, pericapillary albumin deposition that hampers nutrient and oxygen diffusion, and disturbed collagen synthesis and collagen maturation (Broughton et al., Alcohol metabolism leads to formation of acetaldehyde, reactive oxygen radicals, and other molecules that damage healthy tissue. Almost all phases of wound healing are adversely affected by ethanol consumption (Jung et al., Smoking has severe negative effects on all phases of wound healing (Sorensen, Bisphosphates, denosumab, and biologicals can cause severe wound healing problems, with clinical manifestations including ulcers, wound dehiscence, bone necrosis, fistulas, and antrum perforations Figures .Hyperbaric oxygen therapy is not used for normal wound healing, but is indicated in complex compromised acute injuries with tissue crushing, as well as in necrotic infections, osteomyelitis, chronic ulcers, and late complications of radiotherapy (Dauwe et al., HIV-positive patients do not seem to have more complications following tooth extraction Dodson, , but do in vitro studies indicate disturbed wound healing during chemotherapy. However, disturbed wound healing is not a clinically significant finding after extractions in patients with a history of chemotherapy (Dietrich and Antoniades, Chemotherapy for mouth cancer can result in oral mucositis during the active treatment phase, and Patients who undergo radiation therapy due to cancer of the mouth of more than 50 Gy have much greater risk of problems with wound healing after tooth extraction, particularly in the molar region of the mandible (Sulaiman et al., Preoperative radiotherapy due to oral cancer is associated with higher complication than postoperative radiotherapy (Momeni et al., Fibrosis, atrophy, contraction of oral mucosa, fistula formation, wound dehiscence, skin flap reconstructive failure, non-healing wound and skin necrosis are documented side effects of radiation therapy (Dormand et al., In maxillo-facial reconstructions using free flaps, low hemoglobin levels should be avoided, especially when the flap exhibits characteristics of ischemia (Xie et al., Wound healing in the mouth occurs in the presence of many challenges, including a high bacterial and viral load, and usually proceeds undisturbed and with preserved oral function. When a facial or intra-oral wound presents a disturbed healing process, it is recommended to conduct a thorough and judicious examination to eliminate or correct underlying local or general factors.CP, Initiated the review and assist in writing and review. JA, Write the review. RJ and JS, Reviewed the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The results of the RV144 HIV vaccine, in combination with several recent non-human primate vaccine studies continue to highlight the potentially protective role of non-neutralizing Fc functional antibodies in HIV vaccine design. For many currently licensed vaccines, assays that detect antigen-specific antibody titers or neutralization levels have been used as a correlate of protection. However, antibodies can confer protection through multiple other mechanisms beyond neutralization, or mechanisms which are not dependent on total antibody titers. Alternative strategies that allow us to further understand the precise mechanisms by which antibodies confer protection against HIV and other infectious pathogens is vitally important for the development of future vaccines. Systems serology aims to comprehensively survey a diverse array of antibody features and functions, in order to simultaneously examine the mechanisms behind and distinguish the most important antibody features required for protection, thus identifying key targets for future experimental vaccine testing. This review will focus on the technical aspects required for the application of Systems serology and summarizes the recent advances provided by application of this systemic analytical approach. Vaccines are one of the world’s most powerful public health interventions. Many of the currently licensed human vaccines are believed to confer protection through the induction of antigen-specific antibodies . These iThe standard method of assessing vaccine-induced protective humoral immunity is through assays that detect either the level of antigen-specific antibody titres post vaccination, ), the quantity of ‘functional’ antibody responses through inhibition of the pathogen or toxin  for influenza) or opsonophagocytic activity  , 9. ThesThree decades after the discovery of HIV, the journey towards the development of a protective HIV vaccine is still ongoing. While the overarching goal of an HIV antibody-based vaccine is to induce broadly neutralizing antibodies, this historically has not proven to be an easy feat . To dateBased on these discoveries, a major focus of the HIV antibody vaccine field has been dedicated to understanding the functional role of these HIV-binding non-neutralizing antibodies . This haUpon vaccination, humoral diversification forms the foundation of the humoral immune response, that aims to target foreign antigen as broadly and effectively as possible . This reSystems tools have revolutionized our understanding of basic immune processes including immune responses to vaccination, disease and immune development. Key to this developing area of research, is the comprehensive and unbiased collection of data to capture as much information as possible to inform and identify previously unappreciated processes in biology. This field has lead to the development of many OMIC tools including genomics (the whole molecular code) , 35, tra)Biophysical assays , or constant region can also be highly modulated . These cPrior to the results of the RV144 trial, the majority of functional Fc-mediated antibody research focused upon ADCC responses through assays that detected the lysis of target cells or inhibition of viral replication , 60. ManFc-functional immune responses are often dictated by the innate immune effector cell that is being activated and its respective FcγR repertoire. It is for that reason that earlier ADCC studies commonly examined NK cell-specific antibody function, due to the fact that NK cells primarily express a single activating FcγRIIIa (CD16a) allowing for easier interpretation of results . HoweverAs with all experimental assays, standardization and optimization is critical to enable accurate cross-study comparisons. Control samples are essential for validation and quality control. Furthermore, sample and control replicates should be completed for all assays to confirm assay reliability, and data accuracy. Data analysis techniques can be utilized to confirm assay and data quality, these include determining signal to noise ratios or calculating the Z score .It is important to note that a more robust, optimized assay does not necessarily reflect biological relevance. For example many of the most reproducible functional antibody assays utilize cell lines that are representative of functional immune responses , 76. TheThe full spectrum of biophysical and functional assays should ideally be collected from all samples, thus allowing for a sweeping assessment and the application of computational approaches to the entire cohort. While admittedly it is not always feasible or practical to collect entire data sets from large cohorts, estimating smaller sample sizes for reliable analysis should be carefully considered prior to experimental data collection, as this can be influenced by multiple factors, including the computational methods applied and dimensionality of the data (e.g. number antibody features and functions) .machine learning” or data-driven computational approaches have been previously applied to Systems biology and Systems vaccinology  and correlation networks [When all measurements are compiled, systems-level computational analysis can then be applied to probe for mechanistic insights or antibody biomarkers of protection. A variety of different “reviewed , 80) andreviewed . These anetworks –84.supervised’ approaches include the addition of predefined groups or classifications, from which the analysis is based, with the goal of identifying key parameters associated with the predefined groups or “classes”. In the context of Systems serology, these groups may be related to a specific advantageous Fc effector function (e.g. ADCC or ADCP etc.) or clinical outcome (e.g. protective versus non-protective vaccine), with the aim to identify novel correlates of protection or key antibody features associated with Fc effector functions. Supervised analytical techniques that have previously been applied to Systems serology include partial least squares discriminant analysis (PLSDA) and decision tree analyses [In contrast, ‘analyses , 84–86.In addition, current high throughput assays used to measure antibody structure and function can generate tens and more often hundreds of data points per sample  . The strOverall, application of these machine learning computational techniques in Systems serology research, has the ability to highlight the most critical associations between antibody features and functions with protection from HIV infection, thus becoming a highly targeted and comprehensive hypothesis driving tool that can accelerate our understanding of the humoral immune system, and help to identify key areas of interest for further experimentation, vaccine testing or exploration by additional quantitative models.Previous application of Systems biology and vaccinology approaches has resulted in the identification of genetic or immune signatures that correlate with vaccine efficacy for yellow fever , influenIn our application of Systems serology to different human HIV vaccines , we utilA similar supervised LASSO and PLSDA approach was applied to RV144 recipients separated into those with high or low V1V2 responses, as a representation of low versus high risk of infection, based on the original immune correlate analysis . High IgFunctional humoral immune responses are induced through the engagement of immune complexes that consist of varying antibody composition, antigen specificity and FcγR engagement. Thus the interactions required for Fc functions are an ideal model for the application of network and pathway analyses that are commonly applied in bioinformatics analyses . ThSimilar Systems serology approaches have also been applied to several SIV and SHIV vaccine trials , 99, 100In the future, additional Systems serology analysis of vaccine trials in NHP, with known efficacy will provide us additional opportunities to identify correlates of protection. Importantly, NHP vaccine trials provide us with the unique opportunity to dissect responses to a deeper degree, often not possible in human vaccination, both by way of sample collection and information about the challenge virus . While tIt is important to note that the technologies available to measure biophysical antibody features and functions are constantly evolving to allow for the assessment of more diverse cell types, cellular environments, receptors and antigen specificities. No doubt, in the future, many other high throughput assays will be developed to allow for advanced measurements of antibody features. Next-generation sequencing and bioinformatics have already enabled probing of the antibody repertoire and greater understanding of the evolution of broadly neutralizing antibodies, and these techniques could be modified and applied to explore the evolution of polyfunctional non-neutralizing or V1V2 antibodies . Similar