Extracellular DNA facilitates the formation of functional amyloids in Staphylococcus aureus biofilms.

Persistent staphylococcal infections often involve surface-associated communities called biofilms. Staphylococcus aureus biofilm development is mediated by the co-ordinated production of the biofilm matrix, which can be composed of polysaccharides, extracellular DNA (eDNA) and proteins including amyloid fibers. The nature of the interactions between matrix components, and how these interactions contribute to the formation of matrix, remain unclear. Here we show that the presence of eDNA in S. aureus biofilms promotes the formation of amyloid fibers. Conditions or mutants that do not generate eDNA result in lack of amyloids during biofilm growth despite the amyloidogeneic subunits, phenol soluble modulin peptides, being produced. In vitro studies revealed that the presence of DNA promotes amyloid formation by PSM peptides. Thus, this work exposes a previously unacknowledged interaction between biofilm matrix components that furthers our understanding of functional amyloid formation and S. aureus biofilm biology.

Seeking and Finding Positive Youth Development Among Zulu Youth in South African Townships.

A cross-sectional study explored the presence and power of developmental assets in a sample of youth from rural South African townships. Learners (female = 58%; Mage  = 17.1; N = 505) attending three township high schools completed self-report measures of developmental assets and thriving outcomes. Participants reported contextual assets (e.g., family, school, community) in the vulnerable ranges, with gender, family structure, and school type accounting for some differences. Correlation and regression analyses revealed that five asset contexts (family, school, community, personal, social) were uniquely predictive of thriving outcomes. Discussion focuses on contextual expressions of positive youth development among Zulu township youth in challenging environments.

The AgrD N-terminal leader peptide of Staphylococcus aureus has cytolytic and amyloidogenic properties.

Staphylococcus aureus virulence is coordinated through the Agr quorum-sensing system to produce an array of secreted molecules. One important class of secreted virulence factors is the phenol-soluble modulins (PSMs). PSMs are small-peptide toxins that have recently been characterized for their roles in infection, biofilm development, and subversion of the host immune system. In this work, we demonstrate that the signal peptide of the S. aureus quorum-sensing signal, AgrD, shares structural and functional similarities with the PSM family of toxins. The efficacy of this peptide (termed N-AgrD) beyond AgrD propeptide trafficking has never been described before. We observe that N-AgrD, like the PSMs, is found in the amyloid fibrils of S. aureus biofilms and is capable of forming and seeding amyloid fibrils in vitro. N-AgrD displays cytolytic and proinflammatory properties that are abrogated after fibril formation. These data suggest that the N-AgrD leader peptide affects S. aureus biology in a manner similar to that described previously for the PSM peptide toxins. Taken together, our findings suggest that peptide cleavage products can affect cellular function beyond their canonical roles and may represent a class of virulence factors warranting further exploration.

Functional amyloids composed of phenol soluble modulins stabilize Staphylococcus aureus biofilms.

Staphylococcus aureus is an opportunistic pathogen that colonizes the skin and mucosal surfaces of mammals. Persistent staphylococcal infections often involve surface-associated communities called biofilms. Here we report the discovery of a novel extracellular fibril structure that promotes S. aureus biofilm integrity. Biochemical and genetic analysis has revealed that these fibers have amyloid-like properties and consist of small peptides called phenol soluble modulins (PSMs). Mutants unable to produce PSMs were susceptible to biofilm disassembly by matrix degrading enzymes and mechanical stress. Previous work has associated PSMs with biofilm disassembly, and we present data showing that soluble PSM peptides disperse biofilms while polymerized peptides do not. This work suggests the PSMs' aggregation into amyloid fibers modulates their biological activity and role in biofilms.

Hemoglobin promotes Staphylococcus aureus nasal colonization.

Staphylococcus aureus nasal colonization is an important risk factor for community and nosocomial infection. Despite the importance of S. aureus to human health, molecular mechanisms and host factors influencing nasal colonization are not well understood. To identify host factors contributing to nasal colonization, we collected human nasal secretions and analyzed their ability to promote S. aureus surface colonization. Some individuals produced secretions possessing the ability to significantly promote S. aureus surface colonization. Nasal secretions pretreated with protease no longer promoted S. aureus surface colonization, suggesting the involvement of protein factors. The major protein components of secretions were identified and subsequent analysis revealed that hemoglobin possessed the ability to promote S. aureus surface colonization. Immunoprecipitation of hemoglobin from nasal secretions resulted in reduced S. aureus surface colonization. Furthermore, exogenously added hemoglobin significantly decreased the inoculum necessary for nasal colonization in a rodent model. Finally, we found that hemoglobin prevented expression of the agr quorum sensing system and that aberrant constitutive expression of the agr effector molecule, RNAIII, resulted in reduced nasal colonization of S. aureus. Collectively our results suggest that the presence of hemoglobin in nasal secretions contributes to S. aureus nasal colonization.

Stress Among Asian Youth During COVID-19: Moderation by Educational, Spiritual, and Cultural Sources of Belonging.

PURPOSE: The aim of this study is to examine levels of COVID-19 stress among Asian youth-compared to white youth-in a Canadian sample, and whether this stress is moderated by a sense of belonging derived from access to contextual (spiritual, cultural, educational) resources. METHODS: Data are from a longitudinal study of youth in Alberta, Canada. Participants were those who identified as Asian/Southeast Asian (n = 202) or White (n = 772). Data were collected at three waves. Measures included COVID-19 stress, the Child and Youth Resilience Measure-28 Contextual subscale, and demographics. Data were analyzed using multivariate regression. RESULTS: Overall at Wave 3, Asian youth reported significantly higher COVID-19 stress than white youth. In moderation analyses, Asian youth who reported higher Wave 1 Child and Youth Resilience Measure-28 Contextual scores also reported higher Wave 3 COVID-19 stress. CONCLUSIONS: We found that experience of a typically protective factor was altered during COVID-19 for Asian youth in this sample. This finding may be related to societal-level discrimination and inequitable treatment experienced by many Asian communities during the pandemic, but future research is needed to test this mechanism.

COVID-19 and Student Well-Being: Stress and Mental Health during Return-to-School.

Students have been multiply impacted by the COVID-19 pandemic: threats to their own and their family's health, the closure of schools, and pivoting to online learning in March 2020, a long summer of physical distancing, and then the challenge of returning to school in fall 2020. As damaging as the physical health effects of a global pandemic are, much has been speculated about the "second wave" of mental health crises, particularly for school-aged children and adolescents. Yet, few studies have asked students about their experiences during the pandemic. The present study engaged with over two thousand (N = 2,310; 1,288 female; M age = 14.5) 12- to 18-year-old Alberta students during their first few weeks of return-to-school in fall 2020. Students completed an online survey that asked about their perceptions of COVID-19, their fall return-to-school experiences (84.9% returned in-person), their self-reported pandemic-related stress, and their behavior, affect, and cognitive functioning in the first few weeks of September. The majority of students (84.9%) returned to school in person. Students reported moderate and equal concern for their health, family confinement, and maintaining social contact. Student stress levels were also above critical thresholds for 25% of the sample, and females and older adolescents (age 15-18 years) generally reported higher stress indicators as compared to males and younger (age 12-14 years) adolescents. Multivariate analysis showed that stress indicators were positively and significantly correlated with self-reported behavioral concerns (i.e., conduct problems, negative affect, and cognitive/inattention), and that stress arousal (e.g., sleep problems, hypervigilance) accounted for significant variance in behavioral concerns. Results are discussed in the context of how schools can provide both universal responses to students during COVID-19 knowing that most students are coping well, while some may require more targeted strategies to address stress arousal and heightened negative affect.

School-Based Suicide Risk Assessment Using eHealth for Youth: Systematic Scoping Review.

BACKGROUND: Suicide is a leading cause of death among youth and a prominent concern for school mental health providers. Indeed, schools play a key role in suicide prevention, including participating in risk assessments with students expressing suicidal ideation. In the context of the COVID-19 pandemic, many schools now need to offer mental health services, including suicide risk assessment, via eHealth platforms. Post pandemic, the use of eHealth risk assessments will support more accessible services for youth living in rural and remote areas. However, as the remote environment is a new context for many schools, guidance is needed on best practices for eHealth suicide risk assessment among youth. OBJECTIVE: This study aims to conduct a rapid, systematic scoping review to explore promising practices for conducting school-based suicide risk assessment among youth via eHealth (ie, information technologies that allow for remote communication). METHODS: This review included peer-reviewed articles and gray literature published in English between 2000 and 2020. Although we did not find studies that specifically explored promising practices for school-based suicide risk assessment among youth via eHealth platforms, we found 12 peer-reviewed articles and 23 gray literature documents that contained relevant information addressing our broader study purpose; thus, these 35 sources were included in this review. RESULTS: We identified five key recommendation themes for school-based suicide risk assessment among youth via eHealth platforms in the 12 peer-reviewed studies. These included accessibility, consent procedures, session logistics, safety planning, and internet privacy. Specific recommendation themes from the 23 gray literature documents substantially overlapped with and enhanced three of the themes identified in the peer-reviewed literature-consent procedures, session logistics, and safety planning. In addition, based on findings from the gray literature, we expanded the accessibility theme to a broader theme termed youth engagement, which included information on accessibility and building rapport, establishing a therapeutic space, and helping youth prepare for remote sessions. Finally, a new theme was identified in the gray literature findings, specifically concerning school mental health professional boundaries. A second key difference between the gray and peer-reviewed literature was the former's focus on issues of equity and access and how technology can reinforce existing inequalities. CONCLUSIONS: For school mental health providers in need of guidance, we believe that these six recommendation themes (ie, youth engagement, school mental health professional boundaries, consent procedures, session logistics, safety planning, and internet privacy) represent the most promising directions for school-based suicide risk assessment among youth using eHealth tools. However, suicide risk assessment among youth via eHealth platforms in school settings represents a critical research gap. On the basis of the findings of this review, we provide specific recommendations for future research, including the need to focus on the needs of diverse youth.

Relationship between depression severity entry criteria and antidepressant clinical trial outcomes.

BACKGROUND: We assessed whether increasing the minimum prerandomization Hamilton Depression Rating Scale (HAM-D) score to enrich the severity of the depressed sample affects antidepressant trial outcome. METHODS: Using the Food and Drug Administration Summary Basis of Approval reports, we examined outcome data from 51 clinical trials (11,270 depressed patients) evaluating 10 investigational antidepressants. RESULTS: Using four categories of trials with increasing minimum HAM-D entry trial criteria, we found no statistically significant relationship between prerandomization categories and trial outcome overall. Although there were minor differences in trial outcome among the three categories with the lowest entry criteria (mean 49%, range, 44.4%-50.0%), the antidepressant trials requiring the highest prerandomization HAM-D score (> or = 20 HAM-D 17) had the lowest frequency of positive outcomes (20%), chi(2) = 4.04, df =1, p = .04. Paradoxically, high entry criteria requirements failed to increase reliably actual mean total prerandomization HAM-D scores, although mean total prerandomization HAM-D scores and use of flexible dosing were associated with higher rates of positive outcome. A greater placebo response was seen in trials requiring higher prerandomization depressive symptoms. CONCLUSIONS: In summary, requiring higher prerandomization depressive symptoms was not associated with an increased rate of favorable outcomes among these 51 antidepressant trials.

Seizure incidence in psychopharmacological clinical trials: an analysis of Food and Drug Administration (FDA) summary basis of approval reports.

BACKGROUND: Clinical trial data provide an approach to the investigation of the effects of psychopharmacological agents, and psychiatric disorders themselves, on seizure threshold. METHODS: We accessed public domain data from Food and Drug Administration (FDA) Phase II and III clinical trials as Summary Basis of Approval (SBA) reports that noted seizure incidence in trials of psychotropic drugs approved in the United States between 1985 and 2004, involving a total of 75,873 patients. We compared seizure incidence among active drug and placebo groups in psychopharmacological clinical trials and the published rates of unprovoked seizures in the general population. RESULTS: Increased seizure incidence was observed with antipsychotics that was accounted for by clozapine and olanzapine, and with drugs indicated for the treatment of OCD that was accounted for by clomipramine. Alprazolam, bupropion immediate release (IR) form, and quetiapine were also associated with higher seizure incidence. The incidence of seizures was significantly lower among patients assigned to antidepressants compared to placebo (standardized incidence ratio = .48; 95% CI, .36- .61). In patients assigned to placebo, seizure incidence was greater than the published incidence of unprovoked seizures in community nonpatient samples. CONCLUSIONS: Proconvulsant effects are associated with a subgroup of psychotropic drugs. Second-generation antidepressants other than bupropion have an apparent anticonvulsant effect. Depression, psychotic disorders, and OCD are associated with reduced seizure threshold.

Psychiatric diagnosis and clinical trial completion rates: analysis of the FDA SBA reports.

Completion rates may affect the safety and efficacy evaluations of psychotropics. We assessed completion rates in clinical trials evaluating psychotropics for five psychiatric disorders. We also examined differences in completion rates between psychotropics and placebo in each diagnostic category. We reviewed clinical data in the Food and Drug Administration summary basis of approval reports for 20 psychotropics evaluated for the treatment of depression, schizophrenia, obsessive compulsive disorder (OCD), generalized anxiety disorder (GAD), or panic disorder, consisting of 19 710 patients. Patients with OCD had the highest completion rates (78.0%), followed by patients with panic disorder (74.4%), GAD (69.2%), depression (64.7%) and schizophrenia (49.0%). Patients assigned to placebo had significantly lower completion rates in antipsychotic clinical trials. Patients assigned to psychotropics in OCD trials had significantly lower completion rates compared to the placebo group. A greater number of early terminations relating to a lack of efficacy was seen among patients assigned to placebo (17.4%) compared with patients assigned to psychotropics (12.2%). A greater number of early terminations relating to adverse events was seen among patients assigned to psychotropics (10.4%) compared with patients assigned to placebo (4.8%). Our findings suggest that psychiatric diagnosis and treatment assignment (placebo vs psychotropic) were associated with completion rates in clinical trials. These findings may help in the design of future psychopharmacology clinical trials.

BMI, sex, and antidepressant response.

BACKGROUND: Investigators have examined potential mechanisms for the observed differences between men and women in antidepressant response. However, to date no studies have measured the impact of body mass index (BMI) on men's and women's response to selective serotonin re-uptake inhibitors or placebo. METHODS: We evaluated the response to antidepressants and placebo of 274 non-obese (BMI<30) and obese (BMI>30) depressed outpatients participating in Phase II-IV clinical trials. After categorizing men and women into their respective BMI groups, we measured the amount of change each group experienced from baseline to the final visit using the HAM-D-17 and MADRS ratings scales. RESULTS: Compared to women, men assigned to an antidepressant had a significantly lower mean total change on both the HAM-D-17 [non-obese, F(1,88)=5.292, p=0.024; obese, F(1,39)=7.040; p=0.012] and the MADRS [non-obese, F(1,66)=4.049, p=0.048; obese, F(1,27)=8.631, p=0.007]. In fact, obese men showed the smallest difference in antidepressant-placebo response. The results of the ANCOVAs indicated significant main effects of treatment (placebo vs. antidepressant), sex of the patient, and BMI category as well as a significant interaction between all three variables. LIMITATIONS: Patients participating in clinical trials are not necessarily representative of the entire depressed population. In addition, our results include only SSRIs, not other antidepressants. CONCLUSION: Compared to the rest of the depressed sample the subgroup of depressed obese men (n=40) showed little or no therapeutic benefit with SSRI antidepressants. Although our findings may have important clinical implications, replication and further research is warranted in order to understand their underlying mechanisms and their pertinence to dosing strategies.

Study designs and outcomes in antidepressant clinical trials.

Clinical trials of antidepressants are difficult to design and conduct. In fact, more than half of all recent clinical trials of commonly used antidepressants failed to show statistical superiority for the drug over placebo. This is not necessarily because of the ineffectiveness of the antidepressant, but rather because of an increased response to placebo. Factors that may contribute to these findings remain elusive. Using data from U.S. Food and Drug Administration (FDA) Summary Basis of Approval (SBA) reports and from studies conducted by our group, we reviewed methodological factors used in clinical trials of antidepressants. The 2 most notable factors affecting positive trials are (1) the inclusion of patients with more severe depression, and (2) the use of a flexible-dose design; these may yield results identifying true antidepressant-placebo differences. Severely ill patients with depression respond well to antidepressants but poorly to placebo. Flexible dosing paradoxically reduces the response to placebo without augmenting the response to the antidepressant. All of these findings suggest that the use of placebo is mandatory when assessing new antidepressants.

Microbial amyloids--functions and interactions within the host.

The aggregation of proteins into amyloid fibers is a common characteristic of many neurodegenerative disorders including Alzheimer's, Parkinson's, and prion diseases. Amyloid formation was originally characterized in these systems and is traditionally viewed as a consequence of protein misfolding and aggregation. An emerging field of study brings functional amyloids, like those produced by bacteria, into the scientific mainstream, and demonstrates a ubiquitous role for amyloids in living systems. This review aims to summarize what is known about the bacterial amyloids and their interactions within various host environments.

The use of drip flow and rotating disk reactors for Staphylococcus aureus biofilm analysis.

Most microbes in nature are thought to exist as surface-associated communities in biofilms.(1) Bacterial biofilms are encased within a matrix and attached to a surface.(2) Biofilm formation and development are commonly studied in the laboratory using batch systems such as microtiter plates or flow systems, such as flow-cells. These methodologies are useful for screening mutant and chemical libraries (microtiter plates)(3) or growing biofilms for visualization (flow cells)(4). Here we present detailed protocols for growing Staphylococcus aureus in two additional types of flow system biofilms: the drip flow biofilm reactor and the rotating disk biofilm reactor. Drip flow biofilm reactors are designed for the study of biofilms grown under low shear conditions.(5) The drip flow reactor consists of four parallel test channels, each capable of holding one standard glass microscope slide sized coupon, or a length of catheter or stint. The drip flow reactor is ideal for microsensor monitoring, general biofilm studies, biofilm cryosectioning samples, high biomass production, medical material evaluations, and indwelling medical device testing.(6,7,8,9) The rotating disk reactor consists of a teflon disk containing recesses for removable coupons.(10) The removable coupons can by made from any machinable material. The bottom of the rotating disk contains a bar magnet to allow disk rotation to create liquid surface shear across surface-flush coupons. The entire disk containing 18 coupons is placed in a 1000 mL glass side-arm reactor vessel. A liquid growth media is circulated through the vessel while the disk is rotated by a magnetic stirrer. The coupons are removed from the reactor vessel and then scraped to collect the biofilm sample for further study or microscopy imaging. Rotating disc reactors are designed for laboratory evaluations of biocide efficacy, biofilm removal, and performance of anti-fouling materials.(9,11,12,13).

Suicide risk and symptom reduction in patients assigned to placebo in duloxetine and escitalopram clinical trials: analysis of the FDA summary basis of approval reports.

BACKGROUND: We assessed suicide and suicide attempt risk as well as symptom reduction among 3,282 depressed patients participating in duloxetine and escitalopram clinical trials assigned to either an antidepressant or placebo. METHODS: We reviewed the FDA Summary Basis of Approval reports for data regarding safety and efficacy for duloxetine and escitalopram. Furthermore, we compared suicide risk among antidepressant clinical trials in this study with our two previous analyses on seven antidepressant clinical trials. RESULTS: Suicide and suicide attempt risk varied considerably among the three analyses, showing up to ten fold differences. Interestingly, the variability exists across the three reports, rather than between treatments (antidepressants versus placebo). CONCLUSIONS: These findings suggest caution in generalizing suicide risk even from a relatively large number of participants and thus, firm conclusions can only be drawn if the number of participants is overwhelmingly large (approximately two million patients). We also noted similar magnitude of response to placebo and antidepressants among the three studies.

Mortality risk in patients with schizophrenia participating in premarketing atypical antipsychotic clinical trials.

OBJECTIVE: Given the concern that mortality rates may be increased in geriatric patients exposed to atypical antipsychotic agents, we assessed mortality rates for adult patients with schizophrenia assigned to an investigational antipsychotic (olanzapine, quetiapine, risperidone, or ziprasidone), a control antipsychotic (haloperidol or chlorpromazine), or placebo in preapproval clinical development programs to assess relative risk with atypical antipsychotics as compared to typical antipsychotics or placebo. METHOD: We reviewed safety data (from clinical trials conducted from approximately 1982 to 2002) for 16,791 adult patients with schizophrenia (DSM-III or DSM-IV criteria) in U.S. Food and Drug Administration (FDA) Summary Basis of Approval (SBA) reports for 6 antipsychotic drugs. Mortality rates were calculated for each treatment group (investigational agent, active control, or placebo) on the basis of patient exposure years (PEY) and gross mortality. We compared the differences in mortality rates between placebo and investigational agents, active controls, and all antipsychotic drugs combined using odds ratios. RESULTS: By PEY analysis, the mortality rate for patients assigned to placebo treatment was significantly higher (p < .05) than for either the investigational antipsychotic (OR = 0.23, 95% CI = 0.13 to 0.45) or the active control group (OR = 0.19, 95% CI = 0.08 to 0.45). Although rates based on gross mortality were also higher with placebo treatment, statistical significance was only seen when comparing patients assigned to placebo with those assigned to the active control antipsychotic group (OR = 0.35, 95% CI = 0.15 to 0.82). CONCLUSIONS: Despite reported excess mortality with antipsychotic use in elderly patients with dementia, SBA data did not reveal a similar increased risk of antipsychotics in adult patients with schizophrenia. However, methodological limitations of the FDA SBA reports may affect the generalizability of these findings.

Sex differences in antidepressant response in recent antidepressant clinical trials.

Some previous reports suggest that women respond differently than men to antidepressant treatment. Much of this literature compares men and women's response to tricyclics to that of newer antidepressants (SSRIs, SNRI), or only examines one particular antidepressant. This study compares men and women's responses to 6 newer antidepressants. A total of 15 randomized, placebo-controlled trials that included 323 depressed patients were examined for sex differences in antidepressant treatment response. Women had a significantly greater response than men to SSRI antidepressants. A similar trend was seen for those assigned to an SNRI antidepressant, although not to the same extent as with SSRI antidepressants. Although these gender differences in treatment response are not large enough to suggest that gender should guide the clinical use of SSRI and SNRI antidepressants, the results do have implications for the design and interpretation of antidepressant clinical trials. These findings also raise the possibility that antidepressants may work somewhat differently in men and women.