The bystander effect contributes to the accumulation of senescent cells in vivo

Senescent cells accumulate with age in multiple tissues and may cause age-associated disease and functional decline. In vitro, senescent cells induce senescence in bystander cells. To see how important this bystander effect may be for accumulation of senescent cells in vivo, we xenotransplanted senescent cells into skeletal muscle and skin of immunocompromised NSG mice. 3 weeks after the last transplantation, mouse dermal fibroblasts and myofibres displayed multiple senescence markers in the vicinity of transplanted senescent cells, but not where non-senescent or no cells were injected. Adjacent to injected senescent cells, the magnitude of the bystander effect was similar to the increase in senescence markers in myofibres between 8 and 32 months of age. The age-associated increase of senescence markers in muscle correlated with fibre thinning, a widely used marker of muscle aging and sarcopenia. Senescent cell transplantation resulted in borderline induction of centrally nucleated fibres and no significant thinning, suggesting that myofibre aging might be a delayed consequence of senescence-like signalling. To assess the relative importance of the bystander effect versus cell-autonomous senescence, we compared senescent hepatocyte frequencies in livers of wild-type and NSG mice under ad libitum and dietary restricted feeding. This enabled us to approximate cell-autonomous and bystander-driven senescent cell accumulation as well as the impact of immunosurveillance separately. The results suggest a significant impact of the bystander effect for accumulation of senescent hepatocytes in liver and indicate that senostatic interventions like dietary restriction may act as senolytics in immunocompetent animals.

Bystander T Cells: A Balancing Act of Friends and Foes

T cell responses are essential for appropriate protection against pathogens. T cell immunity is achieved through the ability to discriminate between foreign and self-molecules, and this relies heavily on stringent T cell receptor (TCR) specificity. Recently, bystander activated T lymphocytes, that are specific for unrelated epitopes during an antigen-specific response, have been implicated in diverse diseases. Numerous infection models have challenged the classic dogma of T cell activation as being solely dependent on TCR and major histocompatibility complex (MHC) interactions, indicating an unappreciated role for pathogen-associated receptors on T cells. We discuss here the specific roles of bystander activated T cells in pathogenesis, shedding light on the ability of these cells to modulate disease severity independently from TCR recognition.

Circulating human antibody-secreting cells during vaccinations and respiratory viral infections are characterized by high specificity and lack of bystander effect

Surges of serum Abs after immunization and infection are highly specific for the offending Ag, and recent studies demonstrate that vaccines induce transient increases in circulating Ab-secreting cells (ASCs). These ASCs are highly enriched but not universally specific for the immunizing Ag, suggesting that a fraction of these ASCs could arise from polyclonal bystander stimulation of preexisting memory cells to unrelated Ags. This model is proposed to explain maintenance of long-lived serological memory in the absence of Ag exposure. To test this model, we measure the ability of respiratory syncytial virus and influenza virus infection or immunizations to influenza virus, tetanus toxoid, hepatitis B Ag, and human papillomavirus to stimulate bystander memory cells specific for other major environmental Ags that represent a large fraction of the preexisting memory B compartment. Bystander or nonspecific ASC responses to respiratory syncytial virus and tetanus could not be detected above the background levels in healthy adults, despite the presence of circulating memory B cells specific for the corresponding Ags. Nonspecific ASC responses in the healthy subjects and cord blood samples were similar. In contrast, both vaccination and infection induce massive expansion of circulating Ag-specific ASCs without significant increases in the frequencies of ASCs against unrelated Ags. Hence, nonspecific stimulation of memory B cells is unlikely to contribute to the mechanisms of long-term serological memory against major human pathogens. Additionally, high specificity of circulating ASCs after antigenic challenge highlights the diagnostic value of interrogating ASCs as an ideal single-time-point diagnostic immune surrogate for serology during acute infection.

Increased survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac arrest

BACKGROUND

Out of hospital cardiac arrest (OHCA) is common and lethal. It has been suggested that OHCA witnessed by EMS providers is a predictor of survival because advanced help is immediately available. We examined EMS witnessed OHCA from the Resuscitation Outcomes Consortium (ROC) to determine the effect of EMS witnessed vs. bystander witnessed and unwitnessed OHCA.

METHODS

Data were analyzed from a prospective, population-based cohort study in 10 U.S. and Canadian ROC sites. Individuals with non-traumatic OHCA treated 04/01/06-03/31/07 by EMS providers with defibrillation or chest compressions were included. Cases were grouped into EMS-witnessed, bystander witnessed, and unwitnessed and further stratified for bystander CPR. Multiple logistic regressions evaluated the odds ratio (OR) for survival to discharge relative to the EMS-witnessed group after adjusting for age, sex, public/private location of collapse, ROC site, and initial ECG rhythm. Of 9991 OHCA, 1022 (10.2%) of EMS-witnessed, 3369 (33.7%) bystander witnessed, and 5600 (56.1%) unwitnessed.

RESULTS

The most common initial rhythm in the EMS-witnessed group was PEA which was higher than in the bystander- and unwitnessed groups (p<0.001). The adjusted OR (95% CI) of survival compared to the EMS-witnessed group was 0.41, (0.36, 0.46) in bystander witnessed with bystander CPR, 0.37 (0.33, 0.43) in bystander witnessed without bystander CPR, 0.17 (0.14, 0.20) in unwitnessed with bystander CPR and 0.21 (0.18, 0.24) in unwitnessed cases without bystander CPR.

CONCLUSIONS

Immediate application of prehospital care for OHCA may improve survival. Efforts should be made to educate patients to access 9-1-1 for prodromal symptoms.

Exosomes in Cancer Radioresistance

Radiation is a mainstay of cancer therapy. Radioresistance is a significant challenge in the treatment of locally advanced, recurrent and metastatic cancers. The mechanisms of radioresistance are complicated and still not completely understood. Exosomes are 40–150 nm vesicles released by cancer cells that contain pathogenic components, such as proteins, mRNAs, DNA fragments, non-coding RNAs, and lipids. Exosomes play a critical role in cancer progression, including cell-cell communication, tumor-stromal interactions, activation of signaling pathways, and immunomodulation. Emerging data indicate that radiation-derived exosomes increase tumor burden, decrease survival, cause radiation-induced bystander effects and promote radioresistance. In addition, radiation can change the contents of exosomes, which allows exosomes to be used as a prognostic and predictive biomarker to monitor radiation response. Therefore, understanding the roles and mechanisms of exosomes in radiation response may shed light on how exosomes play a role in radioresistance and open a new way in radiotherapy and translational medicine. In this review, we discuss recent advances in radiation-induced exosome changes in components, focus on the roles of exosome in radiation-induced bystander effect in cancer and emphasize the importance of exosomes in cancer progression and radioresistance for developing novel therapy.

Out-of-field cell survival following exposure to intensity-modulated radiation fields

PURPOSE

To determine the in-field and out-of-field cell survival of cells irradiated with either primary field or scattered radiation in the presence and absence of intercellular communication.

METHODS AND MATERIALS

Cell survival was determined by clonogenic assay in human prostate cancer (DU145) and primary fibroblast (AGO1552) cells following exposure to different field configurations delivered using a 6-MV photon beam produced with a Varian linear accelerator.

RESULTS

Nonuniform dose distributions were delivered using a multileaf collimator (MLC) in which half of the cell population was shielded. Clonogenic survival in the shielded region was significantly lower than that predicted from the linear quadratic model. In both cell lines, the out-of-field responses appeared to saturate at 40%-50% survival at a scattered dose of 0.70 Gy in DU-145 cells and 0.24 Gy in AGO1522 cells. There was an approximately eightfold difference in the initial slopes of the out-of-field response compared with the α-component of the uniform field response. In contrast, cells in the exposed part of the field showed increased survival. These observations were abrogated by direct physical inhibition of cellular communication and by the addition of the inducible nitric oxide synthase inhibitor aminoguanidine known to inhibit intercellular bystander effects. Additional studies showed the proportion of cells irradiated and dose delivered to the shielded and exposed regions of the field to impact on response.

CONCLUSIONS

These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields with cellular communication between differentially irradiated cell populations playing an important role. Validation of these observations in additional cell models may facilitate the refinement of existing radiobiological models and the observations considered important determinants of cell survival.

Reactions and coping strategies in lay rescuers who have provided CPR to out-of-hospital cardiac arrest victims: a qualitative study

OBJECTIVE

Cardiopulmonary resuscitation (CPR) provided by community citizens is of paramount importance for out-of-hospital cardiac arrest (OHCA) victims' survival. Fortunately, CPR rates by community citizens seem to be rising. However, the experience of providing CPR is rarely investigated. The aim of this study was to explore reactions and coping strategies in lay rescuers who have provided CPR to OHCA victims.

METHODS, PARTICIPANTS

This is a qualitative study of 20 lay rescuers who have provided CPR to 18 OHCA victims. We used a semistructured interview guide focusing on their experiences after providing CPR.

SETTING

The study was conducted in the Stavanger region of Norway, an area with very high bystander CPR rates.

RESULTS

Three themes emerged from the interview analysis: concern, uncertainty and coping strategies. Providing CPR had been emotionally challenging for all lay rescuers and, for some, had consequences in terms of family and work life. Several lay rescuers experienced persistent mental recurrences of the OHCA incident and had concerns about the outcome for the cardiac arrest victim. Unknown or fatal outcomes often caused feelings of guilt and were particularly difficult to handle. Several reported the need to be acknowledged for their CPR attempts. Health-educated lay rescuers seemed to be less affected than others. A common coping strategy was confiding in close relations, preferably the health educated. However, some required professional help to cope with the OHCA incident.

CONCLUSIONS

Lay rescuers experience emotional and social challenges, and some struggle to cope in life after providing CPR in OHCA incidents. Experiencing a positive patient outcome and being a health-educated lay rescuer seem to mitigate concerns. Common coping strategies are attempts to reduce uncertainty towards patient outcome and own CPR quality. Further studies are needed to determine whether an organised professional follow-up can mitigate the concerns and uncertainty of lay rescuers.

The Use of Virtual Reality in the Study of People's Responses to Violent Incidents

This paper reviews experimental methods for the study of the responses of people to violence in digital media, and in particular considers the issues of internal validity and ecological validity or generalisability of results to events in the real world. Experimental methods typically involve a significant level of abstraction from reality, with participants required to carry out tasks that are far removed from violence in real life, and hence their ecological validity is questionable. On the other hand studies based on field data, while having ecological validity, cannot control multiple confounding variables that may have an impact on observed results, so that their internal validity is questionable. It is argued that immersive virtual reality may provide a unification of these two approaches. Since people tend to respond realistically to situations and events that occur in virtual reality, and since virtual reality simulations can be completely controlled for experimental purposes, studies of responses to violence within virtual reality are likely to have both ecological and internal validity. This depends on a property that we call 'plausibility' - including the fidelity of the depicted situation with prior knowledge and expectations. We illustrate this with data from a previously published experiment, a virtual reprise of Stanley Milgram's 1960s obedience experiment, and also with pilot data from a new study being developed that looks at bystander responses to violent incidents.

Revisiting the Radiobiology of Targeted Alpha Therapy

Targeted alpha therapy (TAT) using alpha particle-emitting radionuclides is in the spotlight after the approval of ²²³RaCl₂ for patients with metastatic castration-resistant prostate cancer and the development of several alpha emitter-based radiopharmaceuticals. It is acknowledged that alpha particles are highly cytotoxic because they produce complex DNA lesions. Hence, the nucleus is considered their critical target, and many studies did not report any effect in other subcellular compartments. Moreover, their physical features, including their range in tissues (<100 μm) and their linear energy transfer (50–230 keV/μm), are well-characterized. Theoretically, TAT is indicated for very small-volume, disseminated tumors (e.g., micrometastases, circulating tumor cells). Moreover, due to their high cytotoxicity, alpha particles should be preferred to beta particles and X-rays to overcome radiation resistance. However, clinical studies showed that TAT might be efficient also in quite large tumors, and biological effects have been observed also away from irradiated cells. These distant effects are called bystander effects when occurring at short distance (<1 mm), and systemic effects when occurring at much longer distance. Systemic effects implicate the immune system. These findings showed that cells can die without receiving any radiation dose, and that a more complex and integrated view of radiobiology is required. This includes the notion that the direct, bystander and systemic responses cannot be dissociated because DNA damage is intimately linked to bystander effects and immune response. Here, we provide a brief overview of the paradigms that need to be revisited.

Lay Bystanders' Perspectives on What Facilitates Cardiopulmonary Resuscitation and Use of Automated External Defibrillators in Real Cardiac Arrests

Background

Many patients who suffer an out‐of‐hospital cardiac arrest will fail to receive bystander intervention (cardiopulmonary resuscitation [CPR] or defibrillation) despite widespread CPR training and the dissemination of automated external defibrillators (AEDs). We sought to investigate what factors encourage lay bystanders to initiate CPR and AED use in a cohort of bystanders previously trained in CPR techniques who were present at an out‐of‐hospital cardiac arrest.

Methods and Results

One‐hundred and twenty‐eight semistructured qualitative interviews with CPR‐trained lay bystanders to consecutive out‐of‐hospital cardiac arrest, where an AED was present were conducted (from January 2012 to April 2015, in Denmark). Purposive maximum variation sampling was used to establish the breadth of the bystander perspective. Twenty‐six of the 128 interviews were chosen for further in‐depth analyses, until data saturation. We used cross‐sectional indexing (using software), and inductive in‐depth thematic analyses, to identify those factors that facilitated CPR and AED use. In addition to prior hands‐on CPR training, the following were described as facilitators: prior knowledge that intervention is crucial in improving survival, cannot cause substantial harm, and that the AED will provide guidance through CPR; prior hands‐on training in AED use; during CPR performance, teamwork (ie, support), using the AED voice prompt and a ventilation mask, as well as demonstrating leadership and feeling a moral obligation to act.

Conclusions

Several factors other than previous hands‐on CPR training facilitate lay bystander instigation of CPR and AED use. The recognition and modification of these factors may increase lay bystander CPR rates and patient survival following an out‐of‐hospital cardiac arrest.

Being a positive bystander: male antiviolence allies' experiences of "stepping up"

As bystander approaches become increasingly prevalent elements of sexual and domestic violence prevention efforts, it is necessary to better understand the factors that support or impede individuals in taking positive action in the face of aggressive or disrespectful behavior from others. This study presents descriptive findings about the bystander experiences of 27 men who recently became involved in antiviolence against women work. More specifically, we describe the consistency with which respondents actively intervene in the speech or behavior of others, the strategies they use, and the factors they weigh as they deliberate taking action. Respondents report a complex and interrelated set of individual and contextual influences on their choices within bystander opportunities, which hold implications for both violence-specific models of bystander behavior and for prevention intervention development.

Distinct phenotypic states and spatial distribution of CD8+ T cell clonotypes in human brain metastases

Metastatic disease in the brain is difficult to control and predicts poor prognosis. Here, we analyze human brain metastases and demonstrate their robust infiltration by CD8+ T cell subsets with distinct antigen specificities, phenotypic states, and spatial localization within the tumor microenvironment. Brain metastases are densely infiltrated by T cells; the majority of infiltrating CD8+ T cells express PD-1. Single-cell RNA sequencing shows significant clonal overlap between proliferating and exhausted CD8+ T cells, but these subsets have minimal clonal overlap with circulating and other tumor-infiltrating CD8+ T cells, including bystander CD8+ T cells specific for microbial antigens. Using spatial transcriptomics and spatial T cell receptor (TCR) sequencing, we show these clonally unrelated, phenotypically distinct CD8+ T cell populations occupy discrete niches within the brain metastasis tumor microenvironment. Together, our work identifies signaling pathways within CD8+ T cells and in their surrounding environment that may be targeted for immunotherapy of brain metastases.

Understanding the Importance of the Lay Responder Experience in Out-of-Hospital Cardiac Arrest: A Scientific Statement From the American Heart Association

Bystander cardiopulmonary resuscitation (CPR) is critical to increasing survival from out-of-hospital cardiac arrest. However, the percentage of cases in which an individual receives bystander CPR is actually low, at only 35% to 40% globally. Preparing lay responders to recognize the signs of sudden cardiac arrest, call 9-1-1, and perform CPR in public and private locations is crucial to increasing survival from this public health problem. The objective of this scientific statement is to summarize the most recent published evidence about the lay responder experience of training, responding, and dealing with the residual impact of witnessing an out-of-hospital cardiac arrest. The scientific statement focuses on the experience-based literature of actual responders, which includes barriers to responding, experiences of doing CPR, use of an automated external defibrillator, the impact of dispatcher-assisted CPR, and the potential for postevent psychological sequelae. The large body of qualitative and observational studies identifies several gaps in crucial knowledge that, if targeted, could increase the likelihood that those who are trained in CPR will act. We suggest using the experience of actual responders to inform more contextualized training, including the implications of performing CPR on a family member, dispelling myths about harm, training and litigation, and recognition of the potential for psychologic sequelae after the event.

Bystanders intervene to impede grooming in Western chimpanzees and sooty mangabeys

Grooming interactions benefit groomers, but may have negative consequences for bystanders. Grooming limits bystanders' grooming access and ensuing alliances could threaten the bystander's hierarchy rank or their previous investment in the groomers. To gain a competitive advantage, bystanders could intervene into a grooming bout to increase their own grooming access or to prevent the negative impact of others' grooming. We tested the impact of dominance rank and social relationships on grooming intervention likelihood and outcome in two sympatric primate species, Western chimpanzees (Pan troglodytes verus) and sooty mangabeys (Cercocebus atys atys). In both species, rather than increasing their own access to preferred partners, bystanders intervened mainly when an alliance between groomers could have a negative impact on them: when the lower-ranking groomer was close to the bystander in rank, when either groomer was an affiliation partner whose services they could lose, or the groomers were not yet strongly affiliated with each other. Thus, bystanders in both species appear to monitor grooming interactions and intervene based on their own dominance rank and social relationships, as well as triadic awareness of the relationship between groomers. While the motivation to intervene did not differ between species, mangabeys appeared to be more constrained by dominance rank than chimpanzees.

Not All Behind Closed Doors: Examining Bystander Involvement in Intimate Partner Violence

It is often said that intimate partner violence (IPV) happens "behind closed doors"; however, research on IPV and other crimes suggests that witnesses are sometimes present. This suggests that bystanders may be in a position to help victims or potential victims of violence. Bystander behavior has been studied primarily in school settings, and consequently, little is known about how often it occurs or what its effects may be in the broader community. This study examined IPV incidents in a rural sample to assess the presence and potential impact of bystanders on victim-reported outcomes. One thousand nine hundred seventy-seven adult participants completed a questionnaire that asked about five violent behaviors (my partner threatened to hurt me; pushed, grabbed, or shook me; hit me; beat me up; sexually assaulted me), bystander characteristics, and victim outcomes (fear; injury; disruption of daily routines; mental health). Adult or teen bystanders were present for each IPV approximately one third of the time, except in the case of sexual assault (14.3%). When a bystander was present, victims reported higher rates of injury, greater disruption in their routines, and poorer mental health. When a bystander's safety was threatened, victims reported more physical injury and more routine disruption. A considerable number of IPV incidents do not happen behind closed doors, and the presence of a bystander was associated with worse outcomes for victims. Prevention efforts for adult IPV may need to take a more cautious or nuanced approach to encouraging bystander action, especially when confronted with more severe incidents. Bystander safety should be a priority for violence prevention.

Bystander Assistance for Trauma Victims in Low- and Middle-Income Countries: A Systematic Review of Prevalence and Training Interventions

OBJECTIVE

Lack of organized prehospital care may contribute to the disproportionate burden of trauma-related deaths in low- and middle-income countries (LMICs). The World Health Organization (WHO) recommends bystander training in basic principles of first aid and victim transport; however, prevalence of bystander or layperson assistance to trauma victims in LMICs has not been well-described, and organized reviews of existing evidence for bystander training are lacking. This systematic review aims to 1) describe the prevalence of bystander or layperson aid or transport for trauma victims in the prehospital setting in LMICs and 2) ascertain impacts of bystander training interventions in these settings.

METHODS

A systematic search of OVID Medline, Cochrane Library, and relevant gray literature was conducted. We included 1) all studies detailing prevalence of bystander-administered aid or transport for trauma victims in LMICs and 2) all randomized controlled trials and observational studies evaluating bystander training interventions. We extracted study characteristics, interventions, and outcomes data. Study quality was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.

RESULTS

Sixty-two studies detailed prevalence of bystander transport and aid. Family members, police, and bus or taxi drivers commonly transported patients; a majority of patients, up to >94%, received aid from bystanders. Twenty-four studies examined impacts of training interventions. Only one study looked at transport interventions; the remainder addressed first aid training. Interventions varied in content, duration, and target learners. Evidence was generally of low quality, but all studies demonstrated improvements in layperson knowledge and skills. Five studies reported a mortality reduction.

CONCLUSIONS

Heterogeneity in data reporting and outcomes limited formal meta-analysis. However, this review shows high rates of bystander involvement in prehospital trauma care and transport in LMICs and highlights the need for bystander training. Bystander training in these settings is feasible and may have an important impact on meaningful outcomes such as mortality. Categories of involved bystanders varied by region and training interventions should be targeted at relevant groups. "Train the trainer" models appear promising in securing community engagement and maximizing participation. Further research is needed to examine the value of bystander transport networks in trauma.

European Food Safety Authority (EFSA), Charistou A, Coja T, Craig P, Hamey P, Martin S, Sanvido O, Chiusolo A, Colas M, Istace F. Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment of plant protection products

This guidance is designed to assist risk assessors and applicants when quantifying potential non-dietary, systemic exposures as part of regulatory risk assessment for plant protection products (PPPs). It is based on the Scientific Opinion on 'Preparation of a Guidance Document on Pesticide Exposure Assessment for Workers, Operators, Residents and Bystanders' developed by the EFSA Panel on Plant Protection Products and their Residue (PPR) in 2010. Highlighting some inconsistencies between the approaches adopted by regulatory authorities, the PPR Panel proposed a number of changes to the practices in use (i.e. use of deterministic methods for individual PPPs; need to perform an acute risk assessment for PPPs that are acutely toxic; use of appropriate percentile for acute or longer term risk assessments). In the first version of the guidance, issued in 2014, several scenarios for outdoor uses were included, with an annexed calculator, as well as recommendations for further research. The guidance has been updated in 2021 with the inclusion of additional scenarios and revision of default values, on the basis of the evaluation of additional evidence. To support users in performing the assessment of exposure and risk, an online calculator, reflecting the guidance content, has been further developed.

Witnessing Bullying at School: The Association between Being a Bystander and Anxiety and Depressive Symptoms

It is well documented that bullying victimization and perpetration are associated with mental health problems, including anxiety and depressive symptoms. Although the majority of students report witnessing bullying as bystanders, very few studies have investigated if negative consequences associated with bullying extend beyond targets and perpetrators to students who are bystanders. The present study examined the association between witnessing bullying and anxiety and depressive symptoms among middle school students. Middle school students (N = 130; grades 6th through 8th) completed questionnaires assessing experiences as a bystander, target, and perpetrator of bullying, as well as anxiety and depressive symptoms. Hierarchical regression analyses were conducted to determine if bystander status was associated with anxiety and depressive symptoms over and above the effects of victimization and perpetration and to examine bullying victimization and perpetration as moderators of these relationships. Analyses indicated being a bystander was associated with higher levels of anxiety (β = .40, p < .001) and depressive symptoms (β = .37, p < .001) even after controlling for frequency of being a target or perpetrator of bullying. Bystanders who were also targets of bullying reported the highest level of depressive symptoms; however, being a target of bullying did not moderate the relationship between being a bystander and anxiety. Furthermore, bullying perpetration did not moderate the relationship between being a bystander and anxiety or depressive symptoms. Findings indicate witnessing bullying uniquely contributes to anxiety and depressive symptoms for middle school students. For student bystanders who are also targets of bullying, depressive symptoms may be particularly high due to co-victimization or re-victimization experienced when witnessing bullying.

Associations between Bystanders and Perpetrators of Online Hate: The Moderating Role of Toxic Online Disinhibition

Hatred directed at members of groups due to their origin, race, gender, religion, or sexual orientation is not new, but it has taken on a new dimension in the online world. To date, very little is known about online hate among adolescents. It is also unknown how online disinhibition might influence the association between being bystanders and being perpetrators of online hate. Thus, the present study focused on examining the associations among being bystanders of online hate, being perpetrators of online hate, and the moderating role of toxic online disinhibition in the relationship between being bystanders and perpetrators of online hate. In total, 1480 students aged between 12 and 17 years old were included in this study. Results revealed positive associations between being online hate bystanders and perpetrators, regardless of whether adolescents had or had not been victims of online hate themselves. The results also showed an association between toxic online disinhibition and online hate perpetration. Further, toxic online disinhibition moderated the relationship between being bystanders of online hate and being perpetrators of online hate. Implications for prevention programs and future research are discussed.

Technology meets TILs: Deciphering T cell function in the -omics era

T cells are at the center of cancer immunology because of their ability to recognize mutations in tumor cells and directly mediate cancer cell killing. Immunotherapies to rejuvenate exhausted T cell responses have transformed the clinical management of several malignancies. In parallel, the development of novel multidimensional analysis platforms, such as single-cell RNA sequencing and high-dimensional flow cytometry, has yielded unprecedented insights into immune cell biology. This convergence has revealed substantial heterogeneity of tumor-infiltrating immune cells in single tumors, across tumor types, and among individuals with cancer. Here we discuss the opportunities and challenges of studying the complex tumor microenvironment with -omics technologies that generate vast amounts of data, highlighting the opportunities and limitations of these technologies with a particular focus on interpreting high-dimensional studies of CD8+ T cells in the tumor microenvironment.

Host and Viral Factors in HIV-Mediated Bystander Apoptosis

Human immunodeficiency virus (HIV) infections lead to a progressive loss of CD4 T cells primarily via the process of apoptosis. With a limited number of infected cells and vastly disproportionate apoptosis in HIV infected patients, it is believed that apoptosis of uninfected bystander cells plays a significant role in this process. Disease progression in HIV infected individuals is highly variable suggesting that both host and viral factors may influence HIV mediated apoptosis. Amongst the viral factors, the role of Envelope (Env) glycoprotein in bystander apoptosis is well documented. Recent evidence on the variability in apoptosis induction by primary patient derived Envs underscores the role of Env glycoprotein in HIV disease. Amongst the host factors, the role of C-C Chemokine Receptor type 5 (CCR5), a coreceptor for HIV Env, is also becoming increasingly evident. Polymorphisms in the CCR5 gene and promoter affect CCR5 cell surface expression and correlate with both apoptosis and CD4 loss. Finally, chronic immune activation in HIV infections induces multiple defects in the immune system and has recently been shown to accelerate HIV Env mediated CD4 apoptosis. Consequently, those factors that affect CCR5 expression and/or immune activation in turn indirectly regulate HIV mediated apoptosis making this phenomenon both complex and multifactorial. This review explores the complex role of various host and viral factors in determining HIV mediated bystander apoptosis.

Bystander's willingness to report theft, physical assault, and sexual assault: the impact of gender, anonymity, and relationship with the offender

This research examines bystander willingness to report three different crimes to the police or campus authorities among a college student sample (n = 295). Twelve original vignettes varied anonymity when reporting, bystander's relationship with the offender (friend or stranger), and crime type. A factorial analysis of variance showed that main effects were found for crime type, bystander's gender, and bystander's relationship with the offender; anonymity was not significant. The physical assault was the most likely to be reported (4.47), followed by theft (3.26), and sexual assault (2.36). Women were more likely than men to report each crime type, and bystanders who were good friends of the offender were less likely to report than strangers. No two- or three-way interactions were significant, but a significant four-way interaction indicated that anonymity, relationship with the offender, and bystander's gender predicted willingness to report for the sexual assault scenario.

Past Life and Future Effects-How Heterologous Infections Alter Immunity to Influenza Viruses

Influenza virus frequently mutates due to its error-prone polymerase. This feature contributes to influenza virus’s ability to evade pre-existing immunity, leading to annual epidemics and periodic pandemics. T cell memory plays a key protective role in the face of an antigenically distinct influenza virus strain because T cell targets are often derived from conserved internal proteins, whereas humoral immunity targets are often sites of increased mutation rates that are tolerated by the virus. Most studies of influenza T cell memory are conducted in naive, specific pathogen free mice and do not account for repetitive influenza infection throughout a lifetime, sequential acute heterologous infections between influenza infections, or heterologous chronic co-infections. By contrast to these mouse models, humans often experience numerous influenza infections, encounter heterologous acute infections between influenza infections, and are infected with at least one chronic virus. In this review, we discuss recent advances in understanding the effects of heterologous infections on the establishment and maintenance of CD8+ T cell immunological memory. Understanding the various factors that affect immune memory can provide insights into the development of more effective vaccines and increase reproducibility of translational studies between animal models and clinical results.

Beyond the Situational Model: Bystander Action Consequences to Intervening in Situations Involving Sexual Violence

Sexual violence is a widely reported problem in college communities. To date, research has largely focused on bystander intervention as one way to help prevent this problem. Although perceived consequences of bystander intervention, such as the weighting of costs and benefits, have been examined, little research has explored what happens after a bystander intervenes. The current study investigated what bystanders report as perceived outcomes and actual consequences of their bystander actions in response to risk for sexual assault. Of the 545 surveyed, 150 reported having taking bystander action in the past month and qualitatively described their bystander behavior and the responses of those parties involved. A range of behavioral responses and intervention methods were identified. The most frequent responses reported by participants were victims conveying positive and perpetrators conveying negative responses. Different types of helping were associated with bystanders reporting different types of responses to their actions. Future research should incorporate additional measures of consequences of bystander intervention. Implications for policy and bystander intervention programs are discussed, stressing the need for bystander intervention programs to address a range of bystander behaviors and explain the potential consequences and risks of intervening.

Effect of real-time visual feedback device 'Quality Cardiopulmonary Resuscitation (QCPR) Classroom' with a metronome sound on layperson CPR training in Japan: a cluster randomized control trial

OBJECTIVES

'Quality Cardiopulmonary Resuscitation (QCPR) Classroom' was recently introduced to provide higher-quality Cardiopulmonary Resuscitation (CPR) training. This study aimed to examine whether novel QCPR Classroom training can lead to higher chest-compression quality than standard CPR training.

DESIGN

A cluster randomised controlled trial was conducted to compare standard CPR training (control) and QCPR Classroom (intervention).

SETTING

Layperson CPR training in Japan.

PARTICIPANTS

Six hundred forty-two people aged over 15 years were recruited from among CPR trainees.

INTERVENTIONS

CPR performance data were registered without feedback on instrumented Little Anne prototypes for 1 min pretraining and post-training. A large classroom was used in which QCPR Classroom participants could see their CPR performance on a big screen at the front; the control group only received instructor's subjective feedback.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcomes were compression depth (mm), rate (compressions per minute (cpm)), percentage of adequate depth (%) and recoil (%). Survey scores were a secondary outcome. The survey included participants' confidence regarding CPR parameters and ease of understanding instructor feedback.

RESULTS

In total, 259 and 238 people in the control and QCPR Classroom groups, respectively, were eligible for analysis. After training, the mean compression depth and rate were 56.1±9.8 mm and 119.2±7.3 cpm in the control group and 59.5±7.9 mm and 116.8±5.5 cpm in the QCPR Classroom group. The QCPR Classroom group showed significantly more adequate depth than the control group (p=0.001). There were 39.0% (95% CI 33.8 to 44.2; p<0.0001) and 20.0% improvements (95% CI 15.4 to 24.7; P<0.0001) in the QCPR Classroom and control groups, respectively. The difference in adequate recoil between pretraining and post-training was 2.7% (95% CI -1.7 to 7.1; pre 64.2±36.5% vs post 66.9%±34.6%; p=0.23) and 22.6% in the control and QCPR Classroom groups (95% CI 17.8 to 27.3; pre 64.8±37.5% vs post 87.4%±22.9%; p<0.0001), respectively.

CONCLUSIONS

QCPR Classroom helped students achieve high-quality CPR training, especially for proper compression depth and full recoil. For good educational achievement, a novel QCPR Classroom with a metronome sound is recommended.