Do athletic ECG changes predict athletic performance in Gurkha recruits?

INTRODUCTION

ECG changes are associated with regular long-term intensive exercise due to electrical manifestations of increased vagal tone, increased ventricular wall thickness and enlarged chamber size. The aim of this study was to further understand the relationship of athletic ECG changes and athletic performance in an athletic population.

METHODS

A retrospective cohort study was performed in 195 Nepali civilian males undergoing selection to the Gurkhas. V̇O2max (maximal oxygen consumption) was estimated from a 1.5-mile run time using Cooper's formula and correlated with athletic ECG adaptations. Variables were explored with univariable and multivariable linear regression.

RESULTS

The median number of athletic changes on ECG was 2 (IQR 1-2). There was no significant correlation (p=0.46) between the number of ECG adaptations and the degree of cardiovascular fitness by estimated V̇O2max (estV̇O2max). We found a negligible but significant correlation between the presence of inferior T wave inversion (TWI) and estV̇O2max (R2=0.03, p=0.02). The multivariable-fitted regression model was: estV̇O2max~Intercept+presence of RVH (right ventricular hypertrophy) voltage criteria+absence of sinus arrhythmia+T wave axis+inferior TWI. The overall regression was statistically significant: R2=0.10, F(df=4, df=189)=[5.4], p=0.0004). All variables in the multivariable model significantly predicted estV̇O2max (p<0.04).

CONCLUSION

ECG changes of athleticism negligibly predict and differentiate athletic performance in our athletic population. The most predictive ECG markers being voltage criteria for left ventricular hypertrophy and RVH. Markers of increased vagal tone were not predictive. TWI, being a marker for disease, was also a marker for athletic performance in this cohort. The number of athletic ECG adaptations did not predict increased athletic performance.

Multiplatform analyses reveal distinct drivers of systemic pathogenesis in adult versus pediatric severe acute COVID-19

The pathogenesis of multi-organ dysfunction associated with severe acute SARS-CoV-2 infection remains poorly understood. Endothelial damage and microvascular thrombosis have been identified as drivers of COVID-19 severity, yet the mechanisms underlying these processes remain elusive. Here we show alterations in fluid shear stress-responsive pathways in critically ill COVID-19 adults as compared to non-COVID critically ill adults using a multiomics approach. Mechanistic in-vitro studies, using microvasculature-on-chip devices, reveal that plasma from critically ill COVID-19 adults induces fibrinogen-dependent red blood cell aggregation that mechanically damages the microvascular glycocalyx. This mechanism appears unique to COVID-19, as plasma from non-COVID sepsis patients demonstrates greater red blood cell membrane stiffness but induces less significant alterations in overall blood rheology. Multiomics analyses in pediatric patients with acute COVID-19 or the post-infectious multi-inflammatory syndrome in children (MIS-C) demonstrate little overlap in plasma cytokine and metabolite changes compared to adult COVID-19 patients. Instead, pediatric acute COVID-19 and MIS-C patients show alterations strongly associated with cytokine upregulation. These findings link high fibrinogen and red blood cell aggregation with endotheliopathy in adult COVID-19 patients and highlight differences in the key mediators of pathogenesis between adult and pediatric populations.

CD8+ lymphocytes do not impact SIV reservoir establishment under ART

Persistence of the human immunodeficiency virus type-1 (HIV-1) latent reservoir in infected individuals remains a problem despite fully suppressive antiretroviral therapy (ART). While reservoir formation begins during acute infection, the mechanisms responsible for its establishment remain unclear. CD8+ T cells are important during the initial control of viral replication. Here we examined the effect of CD8+ T cells on formation of the latent reservoir in simian immunodeficiency virus (SIV)-infected macaques by performing experimental CD8+ depletion either before infection or before early (that is, day 14 post-infection) ART initiation. We found that CD8+ depletion resulted in slower decline of viremia, indicating that CD8+ lymphocytes reduce the average lifespan of productively infected cells during acute infection and early ART, presumably through SIV-specific cytotoxic T lymphocyte (CTL) activity. However, CD8+ depletion did not change the frequency of infected CD4+ T cells in the blood or lymph node as measured by the total cell-associated viral DNA or intact provirus DNA assay. In addition, the size of the persistent reservoir remained the same when measuring the kinetics of virus rebound after ART interruption. These data indicate that during early SIV infection, the viral reservoir that persists under ART is established largely independent of CTL control.

A flow-cytometry-based protocol using diverse cell types for detecting autoantibodies from human plasma and serum samples

Here, we describe a protocol for cell-based detection of autoantibodies from human plasma and serum samples using a standard flow cytometer. The protocol allows detection of autoantibodies against a wide array of extracellular antigens. Antigen coverage is limited to the cell types tested, and researchers will need to further determine if autoantibody-positive samples correlate with cytotoxic or clinical outcomes. This protocol is less expensive and faster to perform when compared to protein microarrays and requires no prior knowledge of potential targets.

For complete details on the use and execution of this protocol, please refer to Wong et al. (2021).

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A flow-cytometry-based protocol to detect the presence of autoantibodies

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Uses input cells to screen plasma or serum samples and identify hits

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Hits are samples reactive with cellular surface antigens, and may be studied further

Broad auto-reactive IgM responses are common in critically ill patients, including those with COVID-19

The pathogenesis of severe coronavirus disease 2019 (COVID-19) remains poorly understood. While several studies suggest that immune dysregulation plays a central role, the key mediators of this process are yet to be defined. Here, we demonstrate that plasma from a high proportion (93%) of critically ill COVID-19 patients, but not healthy controls, contains broadly auto-reactive immunoglobulin M (IgM) and less frequently auto-reactive IgG or IgA. Importantly, these auto-IgMs preferentially recognize primary human lung cells in vitro, including pulmonary endothelial and epithelial cells. By using a combination of flow cytometry, analytical proteome microarray technology, and lactose dehydrogenase (LDH)-release cytotoxicity assays, we identify high-affinity, complement-fixing, auto-reactive IgM directed against 260 candidate autoantigens, including numerous molecules preferentially expressed on the cellular membranes of pulmonary, vascular, gastrointestinal, and renal tissues. These findings suggest that broad IgM-mediated autoimmune reactivity may be involved in the pathogenesis of severe COVID-19, thereby identifying a potential target for therapeutic interventions.