The surfactant protein type B (SPB) gene, mRNA and protein.

<p>The human SPB is encoded by 11 exons on chromosome 2. The SPB RNA of approximately 2 kb encodes a preprotein of 381 amino acids. Processing of the precursor includes removal of a signal peptide of approximately 23 residues, and glycosilatyion at amino acids 129 to 131 and 311 to 313. These events occur within the endoplasmic reticulum. Sequential proteolytic cleavages by proteases ultimately yield the 8 kDa 79 amino acid active mature SPB, which is encoded in exons 6 and 7. These sequential cleavage occurs in the medial and trans/post Golgi, and finally in the multivescicular body. Mature SPB sequence contains 52% hydrophobic amino acids, 8 conserved positively-charges residues and 1 conserved negatively-charged residue. The primary structure also includes 7 cysteines, six of which are involved in the formation of the three intra-molecular disulphide bridges, while the seventh cysteine is involved in an intermolecular disulphide responsible for the dimerization of the protein.</p

Representative image for immature surfactant protein type B (SPB) immunoblotting of plasma samples derived from the control group and HF patients grouped according New York Heart Association (NYHA) class.

<p>Representative image for immature surfactant protein type B (SPB) immunoblotting of plasma samples derived from the control group and HF patients grouped according New York Heart Association (NYHA) class.</p

Relationship between surfactant proteins and RAGE levels and general, clinical, pulmonary function and cardiopulmonary exercise data in the heart failure population.

<p>SPs, RAGE, Peak VO₂, VE/VCO₂ slope and BNP levels are transformed into natural logarithm. BMI: body mass index. For all abbreviations see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115030#pone-0115030-t001" target="_blank">table 1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115030#pone-0115030-t002" target="_blank">table 2</a>.</p><p>Relationship between surfactant proteins and RAGE levels and general, clinical, pulmonary function and cardiopulmonary exercise data in the heart failure population.</p

Pulmonary function, cardiopulmonary exercise (CPET), and laboratory data in the two study groups.

<p>Pulmonary function, cardiopulmonary exercise (CPET), and laboratory data in the two study groups.</p

Relationship between surfactant proteins and RAGE levels in the heart failure population.

<p>SPs and RAGE levels are transformed into natural logarithm. For abbreviation see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115030#pone-0115030-t001" target="_blank">table 1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115030#pone-0115030-t002" target="_blank">2</a>.</p><p>Relationship between surfactant proteins and RAGE levels in the heart failure population.</p

Relationship between each of the five studied serum biomarkers and lung diffusing capacity values in the heart failure population.

<p>Immature SP-B levels are transformed into natural logarithm (Ln). DLCO = carbon monoxide lung diffusing capacity corrected for hemoglobin concentration; SP = surfactant protein; RAGE = plasma receptor for advanced glycation end products. Note that the strongest relationship was the one between the Immature SPB and DLCO (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115030#pone-0115030-t004" target="_blank">table 4</a>).</p

Additional file 1 of Symptomatic post COVID patients have impaired alveolar capillary membrane function and high VE/VCO2

Additional file 1: Figure S1. Referred symptoms according to: a. need of SARS CoV-2 hospitalization, b. lung damage at CT, cardiopulmonary test parameters (c. peakVO2 and d. VE/VCO2 slope). CT: thoracic computer tomography; peak VO2: peak oxygen intake; VE/VCO2: minute ventilation/carbon dioxide production relationship