Pathogen disgust is associated with interpersonal bias among healthcare professionals.

Background and objectives: Pathogen avoidance is a fundamental motive that shapes many aspects of human behavior including bias against groups stereotypically linked to disease (e.g. immigrants, outgroup members). This link has only been examined in convenience samples and it is unknown how pathogen avoidance processes operate in populations experiencing prolonged and heightened pathogen threat such as healthcare professionals. We examined whether healthcare professionals demonstrate the same link between pathogen disgust and intergroup bias as has been documented among the general population. Methodology: Participants (N = 317; 210 healthcare professionals) were recruited using snowball sampling to take an online survey. Participants completed the Three Domain Disgust Scale to assess pathogen, sexual and moral disgust. Participants then rated their perceptions of a fictitious immigrant group ('Krasneeans') and the degree to which they endorsed group-binding moral values. Results: Compared to control participants, healthcare professionals reported lower levels of pathogen disgust, but not sexual or moral disgust. However, regardless of profession, higher pathogen disgust was associated with viewing Krasneeans as less likeable and more unclean. Additionally, regardless of profession, higher pathogen disgust was associated with greater endorsement of group-binding moral values, although healthcare professionals reported greater overall endorsement of group-binding moral values than did control participants. Conclusions and implications: Although healthcare professionals demonstrated lower levels of pathogen disgust, they nevertheless exhibited largely the same relationship between pathogen disgust and interpersonal biases as did control participants. One practical implication of this association is that pathogen avoidance motives may contribute to inequitable patient treatment in healthcare settings.

Mucin and Agitation Shape Predation of Escherichia coli by Lytic Coliphage.

The ability of bacteriophage (phage), abundant within the gastrointestinal microbiome, to regulate bacterial populations within the same micro-environment offers prophylactic and therapeutic opportunities. Bacteria and phage have both been shown to interact intimately with mucin, and these interactions invariably effect the outcomes of phage predation within the intestine. To better understand the influence of the gastrointestinal micro-environment on phage predation, we employed enclosed, in vitro systems to investigate the roles of mucin concentration and agitation as a function of phage type and number on bacterial killing. Using two lytic coliphage, T4 and PhiX174, bacterial viability was quantified following exposure to phages at different multiplicities of infection (MOI) within increasing, physiological levels of mucin (0-4%) with and without agitation. Comparison of bacterial viability outcomes demonstrated that at low MOI, agitation in combination with higher mucin concentration (>2%) inhibited phage predation by both phages. However, when MOI was increased, PhiX predation was recovered regardless of mucin concentration or agitation. In contrast, only constant agitation of samples containing a high MOI of T4 demonstrated phage predation; briefly agitated samples remained hindered. Our results demonstrate that each phage-bacteria pairing is uniquely influenced by environmental factors, and these should be considered when determining the potential efficacy of phage predation under homeostatic or therapeutic circumstances.

Time Domains of Hypoxia Responses and -Omics Insights.

The ability to respond rapidly to changes in oxygen tension is critical for many forms of life. Challenges to oxygen homeostasis, specifically in the contexts of evolutionary biology and biomedicine, provide important insights into mechanisms of hypoxia adaptation and tolerance. Here we synthesize findings across varying time domains of hypoxia in terms of oxygen delivery, ranging from early animal to modern human evolution and examine the potential impacts of environmental and clinical challenges through emerging multi-omics approaches. We discuss how diverse animal species have adapted to hypoxic environments, how humans vary in their responses to hypoxia (i.e., in the context of high-altitude exposure, cardiopulmonary disease, and sleep apnea), and how findings from each of these fields inform the other and lead to promising new directions in basic and clinical hypoxia research.

Norepinephrine induces growth of Desulfovibrio vulgaris in an iron dependent manner.

Desulfovibrio spp. is a commensal sulfate reducing bacterium that is present in small numbers in the gastrointestinal tract. Increased concentrations of Desulfovibrio spp. (blooms) have been reported in patients with inflammatory bowel disease and irritable bowel syndrome. Since stress has been reported to exacerbate symptoms of these chronic diseases, this study examined whether the stress catecholamine norepinephrine (NE) promotes Desulfovibrio growth. Norepinephrine-stimulated growth has been reported in other bacterial taxa, and this effect may depend on the availability of the micronutrient iron. OBJECTIVES: This study tested whether norepinephrine exposure affects the in vitro growth of Desulfovibrio vulgaris in an iron dependent manner. METHODS: DSV was incubated in a growth medium with and without 1 µm of norepinephrine. An additional growth assay added the iron chelator deferoxamine in NE exposed DSV. Iron regulatory genes were assessed with and without the treatment of NE and Deferoxamine. RESULTS: We found that norepinephrine significantly increased growth of D. vulgaris. Norepinephrine also increased bacterial production of hydrogen sulfide. Additionally, norepinephrine significantly increased bacterial expression in three of the four tested iron regulatory genes. The iron chelator deferoxamine inhibited growth of D. vulgaris in a dose-dependent manner and reversed the effect of norepinephrine on proliferation of D. vulgaris and on bacterial expression of iron regulatory genes. CONCLUSION: The data presented in this work suggests that promotion of D. vulgaris growth by norepinephrine is iron dependent.

Associations Between Change Over Time in Pandemic-Related Stress and Change in Physical Activity.

BACKGROUND: Physical activity (PA) mitigated psychological distress during the initial weeks of the COVID-19 pandemic, yet not much is known about whether PA had effects on stress in subsequent months. We examined the relationship between change over time in COVID-related stress and self-reported change in PA between March and July 2020. METHODS: Latent growth modeling was used to examine trajectories of change in pandemic-related stress and test their association with self-reported changes in PA in an international sample (n = 679). RESULTS: The participants reported a reduction in pandemic-related stress between April and July of 2020. Significant linear (factor mean = -0.22) and quadratic (factor mean = 0.02) changes (Ps < .001) were observed, indicating a deceleration in stress reduction over time. Linear change was related to change in PA such that individuals who became less active during the pandemic reported less stress reduction over time compared with those who maintained or increased their PA during the pandemic. CONCLUSIONS: Individuals who experienced the greatest reduction in stress over time during the pandemic were those who maintained their activity levels or became more active. Our study cannot establish a causal relationship between these variables, but the findings are consistent with other work showing that PA reduces stress.

Cytokine storms, evolution and COVID-19.

Since the identification of severe illness caused by the novel coronavirus SARS-CoV-2, the role of the host immune system in causing disease has attracted widespread attention, along with intense interest in medical interventions that target the host immune response. A wide variety of agents have been proposed to treat a cytokine storm in coronavirus disease 2019 (COVID-19), but so far, only one class of medications, corticosteroids, has proved useful. In recent decades, experimental therapies for cytokine storms have been tried and mostly failed to help patients with severe sepsis and other infections. We summarize this history in order to frame expectations for novel interventions in COVID-19 and to bring an evolutionary medicine perspective to the concept of cytokine storms and their treatment.

Standard Bacteriophage Purification Procedures Cause Loss in Numbers and Activity.

For decades, bacteriophage purification has followed structured protocols focused on generating high concentrations of phage in manageable volumes. As research moves toward understanding complex phage populations, purification needs have shifted to maximize the amount of phage while maintaining diversity and activity. The effects of standard phage purification procedures such as polyethylene glycol (PEG) precipitation and cesium chloride (CsCl) density gradients on both diversity and activity of a phage population are not known. We have examined the effects of PEG precipitation and CsCl density gradients on a number of known phage (M13, T4, and ΦX 174) of varying structure and size, individually and as mixed sample. Measurement of phage numbers and activity throughout the purification process was performed. We demonstrate that these methods, used routinely to generate "pure" phage samples, are in fact detrimental to retention of phage number and activity; even more so in mixed phage samples. As such, minimal amounts of processing are recommended to introduce less bias and maintain more of a phage population.

High-altitude pulmonary edema.

Lay summary: High Altitude Pulmonary Edema (HAPE) is a potentially fatal disease of altitude, in which the lungs can become filled with fluid. In this article we explore the mechanisms causing this condition and how it can be viewed as a condition of a mismatch between current environment and evolutionary experience.

Conflicts over calcium and the treatment of COVID-19.

Several recent studies have provided evidence that use of calcium channel blockers (CCBs), especially amlodipine and nifedipine, can reduce mortality from coronavirus disease 2019 (COVID-19). Moreover, hypocalcemia (a reduced level of serum ionized calcium) has been shown to be strongly positively associated with COVID-19 severity. Both effectiveness of CCBs as antiviral therapy, and positive associations of hypocalcemia with mortality, have been demonstrated for many other viruses as well. We evaluate these findings in the contexts of virus-host evolutionary conflicts over calcium metabolism, and hypocalcemia as either pathology, viral manipulation or host defence against pathogens. Considerable evidence supports the hypothesis that hypocalcemia represents a host defence. Indeed, hypocalcemia may exert antiviral effects in a similar manner as do CCBs, through interference with calcium metabolism in virus-infected cells. Prospective clinical studies that address the efficacy of CCBs and hypocalcemia should provide novel insights into the pathogenicity and treatment of COVID-19 and other viruses.

Let fever do its job: The meaning of fever in the pandemic era.

Although fever is one of the main presenting symptoms of COVID-19 infection, little public attention has been given to fever as an evolved defense. Fever, the regulated increase in the body temperature, is part of the evolved systemic reaction to infection known as the acute phase response. The heat of fever augments the performance of immune cells, induces stress on pathogens and infected cells directly, and combines with other stressors to provide a nonspecific immune defense. Observational trials in humans suggest a survival benefit from fever, and randomized trials published before COVID-19 do not support fever reduction in patients with infection. Like public health measures that seem burdensome and excessive, fevers involve costly trade-offs but they can prevent infection from getting out of control. For infections with novel SARS-CoV-2, the precautionary principle applies: unless evidence suggests otherwise, we advise that fever should be allowed to run its course. Lay summary: For COVID-19, many public health organizations have advised treating fever with medicines such as acetaminophen or ibuprofen. Even though this is a common practice, lowering body temperature has not improved survival in laboratory animals or in patients with infections. Blocking fever can be harmful because fever, along with other sickness symptoms, evolved as a defense against infection. Fever works by causing more damage to pathogens and infected cells than it does to healthy cells in the body. During pandemic COVID-19, the benefits of allowing fever to occur probably outweigh its harms, for individuals and for the public at large.

The pandemic exposes human nature: 10 evolutionary insights.

Humans and viruses have been coevolving for millennia. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, the virus that causes COVID-19) has been particularly successful in evading our evolved defenses. The outcome has been tragic-across the globe, millions have been sickened and hundreds of thousands have died. Moreover, the quarantine has radically changed the structure of our lives, with devastating social and economic consequences that are likely to unfold for years. An evolutionary perspective can help us understand the progression and consequences of the pandemic. Here, a diverse group of scientists, with expertise from evolutionary medicine to cultural evolution, provide insights about the pandemic and its aftermath. At the most granular level, we consider how viruses might affect social behavior, and how quarantine, ironically, could make us susceptible to other maladies, due to a lack of microbial exposure. At the psychological level, we describe the ways in which the pandemic can affect mating behavior, cooperation (or the lack thereof), and gender norms, and how we can use disgust to better activate native "behavioral immunity" to combat disease spread. At the cultural level, we describe shifting cultural norms and how we might harness them to better combat disease and the negative social consequences of the pandemic. These insights can be used to craft solutions to problems produced by the pandemic and to lay the groundwork for a scientific agenda to capture and understand what has become, in effect, a worldwide social experiment.

Kombucha: a novel model system for cooperation and conflict in a complex multi-species microbial ecosystem.

Kombucha, a fermented tea beverage with an acidic and effervescent taste, is composed of a multispecies microbial ecosystem with complex interactions that are characterized by both cooperation and conflict. In kombucha, a complex community of bacteria and yeast initiates the fermentation of a starter tea (usually black or green tea with sugar), producing a biofilm that covers the liquid over several weeks. This happens through several fermentative phases that are characterized by cooperation and competition among the microbes within the kombucha solution. Yeast produce invertase as a public good that enables both yeast and bacteria to metabolize sugars. Bacteria produce a surface biofilm which may act as a public good providing protection from invaders, storage for resources, and greater access to oxygen for microbes embedded within it. The ethanol and acid produced during the fermentative process (by yeast and bacteria, respectively) may also help to protect the system from invasion by microbial competitors from the environment. Thus, kombucha can serve as a model system for addressing important questions about the evolution of cooperation and conflict in diverse multispecies systems. Further, it has the potential to be artificially selected to specialize it for particular human uses, including the development of antimicrobial ecosystems and novel materials. Finally, kombucha is easily-propagated, non-toxic, and inexpensive, making it an excellent system for scientific inquiry and citizen science.

The Emperor Has No Clothes? Searching for Dysregulation in Sepsis.

The core conception of sepsis-that it is a dysregulated state-is a powerful and durable idea that has inspired decades of research. But is it true that the body's response to sepsis is dysregulated? To answer that question, this review surveyed the history of trials of experimental sepsis treatments targeting the host response. Sepsis survival is not improved by blocking one or many immune pathways. Similarly, sepsis is resistant to treatment by normalizing one or many physiologic parameters simultaneously. The vast majority of interventions are either ineffective or harmful. With this track record of failure, it is time to consider the alternative hypothesis-regulation instead of dysregulation-and the possibility that sepsis traits are often functional, and that some physiologic alterations in sepsis do more good than harm, while others are neutral. This review discusses the implications of this perspective for the future of sepsis research.

How nurse gender influences patient priority assignments in US emergency departments.

The goals of this study were to compare whether emergency department (ED) patients' pain intensity (PI) is measured differently by male and female nurses and to determine whether PI, heart rate (HR), and respiratory rate (RR) were used to prioritize patient urgency differently by male and female nurses. The associations between patients' PI|HR|RR and the Emergency Severity Index (ESI) scores they were assigned by attending nurses were analyzed using a national database of electronic medical records of US Veterans Affairs ED patients from 2008 to 2012. A total of 129,991 patients presenting for emergency care (Mage = 59.5, 92% males) and their triage nurses (n = 774, Mage = 47.5, 18% males) were analyzed, resulting in a total of 359,642 patient-provider interactions. Patients' PI did not differ by the nurse's gender; however a cross-classified mixed-effects model showed that nurse gender influenced how PI and RR measurements informed the ESI levels that male patients received. Higher PI levels were associated with more urgent (higher priority) ESI levels by female nurses, yet less urgent ESI levels by male nurses. In contrast, male patients with high RR received more urgent ESI levels by male nurses, whereas the nurse gender did not influence ESI assignments for female patients. These findings show that ED patients receive disparate treatment based on inherent characteristics of their triage nurses, and more standardized (eg, automated) protocols that can account for implicit social factors on health care practice for reliably assessing and prioritizing ED patients may be currently warranted.

Salivary microbiomes of indigenous Tsimane mothers and infants are distinct despite frequent premastication.

BACKGROUND: Premastication, the transfer of pre-chewed food, is a common infant and young child feeding practice among the Tsimane, forager-horticulturalists living in the Bolivian Amazon. Research conducted primarily with Western populations has shown that infants harbor distinct oral microbiota from their mothers. Premastication, which is less common in these populations, may influence the colonization and maturation of infant oral microbiota, including via transmission of oral pathogens. We collected premasticated food and saliva samples from Tsimane mothers and infants (9-24 months of age) to test for evidence of bacterial transmission in premasticated foods and overlap in maternal and infant salivary microbiota. We extracted bacterial DNA from two premasticated food samples and 12 matched salivary samples from maternal-infant pairs. DNA sequencing was performed with MiSeq (Illumina). We evaluated maternal and infant microbial composition in terms of relative abundance of specific taxa, alpha and beta diversity, and dissimilarity distances. RESULTS: The bacteria in saliva and premasticated food were mapped to 19 phyla and 400 genera and were dominated by Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. The oral microbial communities of Tsimane mothers and infants who frequently share premasticated food were well-separated in a non-metric multi-dimensional scaling ordination (NMDS) plot. Infant microbiotas clustered together, with weighted Unifrac distances significantly differing between mothers and infants. Infant saliva contained more Firmicutes (p < 0.01) and fewer Proteobacteria (p < 0.05) than did maternal saliva. Many genera previously associated with dental and periodontal infections, e.g. Neisseria, Gemella, Rothia, Actinomyces, Fusobacterium, and Leptotrichia, were more abundant in mothers than in infants. CONCLUSIONS: Salivary microbiota of Tsimane infants and young children up to two years of age do not appear closely related to those of their mothers, despite frequent premastication and preliminary evidence that maternal bacteria is transmitted to premasticated foods. Infant physiology and diet may constrain colonization by maternal bacteria, including several oral pathogens.

Resource conflict and cooperation between human host and gut microbiota: implications for nutrition and health.

Diet has been known to play an important role in human health since at least the time period of the ancient Greek physician Hippocrates. In the last decade, research has revealed that microorganisms inhabiting the digestive tract, known as the gut microbiota, are critical factors in human health. This paper draws on concepts of cooperation and conflict from ecology and evolutionary biology to make predictions about host-microbiota interactions involving nutrients. To optimally extract energy from some resources (e.g., fiber), hosts require cooperation from microbes. Other nutrients can be utilized by both hosts and microbes (e.g., simple sugars, iron) in their ingested form, which may lead to greater conflict over these resources. This framework predicts that some negative health effects of foods are driven by the direct effects of these foods on human physiology and by indirect effects resulting from microbiome-host competition and conflict (e.g., increased invasiveness and inflammation). Similarly, beneficial effects of some foods on host health may be enhanced by resource sharing and other cooperative behaviors between host and microbes that may downregulate inflammation and virulence. Given that some foods cultivate cooperation between hosts and microbes while others agitate conflict, host-microbe interactions may be novel targets for interventions aimed at improving nutrition and human health.

Patient Ethnicity Affects Triage Assessments and Patient Prioritization in U.S. Department of Veterans Affairs Emergency Departments.

Ethnic minority patients receive lower priority triage assignments in Veteran's Affairs (VA) emergency departments (EDs) compared to White patients, but it is currently unknown whether this disparity arises from generalized biases across the triage assessment process or from differences in how objective and/or subjective institution-level or person-level information is incorporated into the triage assessment process, thus contributing to disparate treatment.The VA database of electronic medical records of patients who presented to the VA ED from 2008 to 2012 was used to measure patient ethnicity, self-reported pain intensity (PI) levels, heart rate (HR), respiratory rate (RR), and nurse-provided triage assignment, the Emergency Severity Index (ESI) score. Multilevel, random effects linear modeling was used to control for demographic and clinical characteristics of patients as well as age, gender, and experience of triage nurses.A total of 359,642 patient/provider encounters between 129,991 VA patients and 774 nurses were included in the study. Patients were 61% non-Hispanic White [NHW], 28% African-American, 7% Hispanic, 2% Asian-American, <1% American Indian/Alaska Native, and 1% mixed ethnicity. After controlling for demographic characteristics of nurses and patients, African-American, Hispanic, and mixed-ethnicity patients reported higher average PI scores but lower HRs and RRs than NHW patients. NHW patients received higher priority ESI ratings with lower PI when compared against African-American patients. NHW patients with low to moderate HRs also received higher priority ESI scoring than African-American, Hispanic, Asian-American, and Mixed-ethnicity patients; however, when HR was high NHWs received lower priority ESI ratings than each of the minority groups (except for African-Americans).This study provides evidence for systemic differences in how patients' vital signs are applied for determining ESI scores for different ethnic groups. Additional prospective research will be needed to determine how this specific person-level mechanism affects healthcare quality and outcomes.

Sulfate-reducing bacteria impairs working memory in mice.

The ability of gut microbes to bi-directionally communicate with the brain and vice versa form the basis of the gut microbiome-central nervous system axis. It has been shown that inoculation with pathogenic gut bacteria alters the behavior of mice; however, it is not known whether or not non-pathogenic resident microbes have similar effects. In this study, we tested the hypothesis that the administration of sulfate-reducing bacteria (SRB), a specific group of resident gut bacteria that generate hydrogen sulfide (H2S), impair learning and memory performance in mice tested in an 8-arm radial maze and Morris water maze. We found that mice spent more time in the center of the maze when they were gavaged with live SRB as compared to mice given saline (control), lactulose+mannitol (L/M), or killed SRB. SRB-gavaged mice were also tested using the Morris water maze and were found to take longer to complete the test, spend more time further from the platform, and have a longer path length to reach the platform. This effect of SRB on maze performance was associated with a higher concentration of H2S in the small intestine and cecum. We conclude that SRB, a specific resident gut bacterial species, could impair cognitive function in mice.

Birth weight predicted baseline muscular efficiency, but not response of energy expenditure to calorie restriction: An empirical test of the predictive adaptive response hypothesis.

OBJECTIVES: Aiming to test the evolutionary significance of relationships linking prenatal growth conditions to adult phenotypes, this study examined whether birth size predicts energetic savings during fasting. We specifically tested a Predictive Adaptive Response (PAR) model that predicts greater energetic saving among adults who were born small. METHODS: Data were collected from a convenience sample of young adults living in Albuquerque, NM (n = 34). Indirect calorimetry quantified changes in resting energy expenditure (REE) and active muscular efficiency that occurred in response to a 29-h fast. Multiple regression analyses linked birth weight to baseline and postfast metabolic values while controlling for appropriate confounders (e.g., sex, body mass). RESULTS: Birth weight did not moderate the relationship between body size and energy expenditure, nor did it predict the magnitude change in REE or muscular efficiency observed from baseline to after fasting. Alternative indicators of birth size were also examined (e.g., low v. normal birth weight, comparison of tertiles), with no effects found. However, baseline muscular efficiency improved by 1.1% per 725 g (S.D.) increase in birth weight (P = 0.037). CONCLUSIONS: Birth size did not influence the sensitivity of metabolic demands to fasting-neither at rest nor during activity. Moreover, small birth size predicted a reduction in the efficiency with which muscles convert energy expended into work accomplished. These results do not support the ascription of adaptive function to phenotypes associated with small birth size. © 2015 Wiley Periodicals, Inc. Am. J. Hum. Biol. 28:484-492, 2016. © 2015 Wiley Periodicals, Inc.