A systematic review and meta-analysis of the IgA seroprevalence in COVID-19 patients: Is there a role for IgA in COVID-19 diagnosis or severity?

Nowadays, Coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the most important health problems. The dynamics and nature of humoral responses are relevant to determine the efficacy of both, diagnostic tests and developed vaccines. Since the role of IgA in the COVID-19 disease is not fully understood, we have systematically reviewed the scientific literature on antibody IgA immunity to SARS-CoV-2 to determine if IgA could be useful as a diagnostic tool or as a biomarker of severity.

Increased calcium leak associated with reduced calsequestrin expression in hyperthyroid cardiomyocytes.

Introduction: Calcium (Ca) leak during cardiac diastole is chiefly mediated by intracellular Ca channel/Ryanodine Receptors. Increased diastolic Ca leak has been proposed as the mechanism underlying the appearance of hereditary arrhythmias. However, little is known about alterations in diastolic Ca leak and the specific roles played by key intracellular Ca-handling proteins in hyperthyroidism, a known arrhythmogenic condition.

[Ryanodine receptor, calcium leak and arrhythmias].

The participation of the ionic Ca(2+) release channel/ryanodine receptor in cardiac excitation-contraction coupling is well known since the late '80s, when various seminal papers communicated its purification for the first time and its identity with the "foot" structures located at the terminal cisternae of the sarcoplasmic reticulum. In addition to its main role as the Ca(2+) channel responsible for the transient Ca(2+) increase that activates the contractile machinery of the cardiomyocytes, the ryanodine receptor releases Ca(2+) during the relaxation phase of the cardiac cycle, giving rise to a diastolic Ca(2+) leak. In normal physiological conditions, diastolic Ca(2+) leak regulates the proper level of luminal Ca(2+), but in pathological conditions it participates in the generation of both, acquired and hereditary arrhythmias.