The crystal structure of zebrafish IL-22 reveals an evolutionary, conserved structure highly similar to that of human IL-22.

The class II cytokine family consists of small α-helical signaling proteins including the interleukin-10 (IL-10)/IL-22 family, as well as interferons (IFNs). They regulate the innate immune response and in addition have an important role in protecting epithelial tissues. Teleost fish possess a class II cytokine system surprisingly similar to that of humans, and thus zebrafish offers an attractive model organism for investigating the role of class II cytokines in inflammation. However, the evolution of class II cytokines is critical to understand if we are to take full advantage of zebrafish as a model system. The small size and fast evolution of these cytokines obscure phylogenetic analyses based purely on sequences, but one can overcome this obstacle by using information contained within the structure of those molecules. Here we present the crystal structure of IL-22 from zebrafish (zIL-22) solved at 2.1 Å, which displays a typical class II cytokine architecture. We generated a structure-guided alignment of vertebrate class II cytokines and used it for phylogenetic analysis. Our analysis suggests that IL-22 and IL-26 arose early during the evolution of the IL-10-like cytokines. Thus, we propose an evolutionary scenario of class II cytokines in vertebrates, based on genomic and structural data.

[Results of a hemodynamic study of valve diseases surgically treated with prosthesis]. / Résultats de l'étude hémodynamique des valvulopathies opérées par prothèse

The haemodynamic status after valve replacement surgery and the preoperative haemodynamic parameters have been studied for their predictive value in a series of 217 patients who have had aortic, mitral or mitro-aortic valve replacements; all cases had a preoperative catheterisation, and 132 had a postoperative catheterisation at an average of 15 months postoperative. The following conclusions have been drawn from the study: 1. The operation (which consisted of replacement with a Starr valve with Silastein ball-valve in 8 cases out of 10) resulted in a substantial, and statistically significant, improvement in the minor circulation pressures and in the cardiac index. The ejection fraction also increases in most cases. 2. The increase in the cardiac index is significantly greater in aortic stenosis than in aortic incompetence, and in the aortic group than in the mitral group. 3. Improvement is early, and occurs within the first few weeks, in the aortic group; it occurs more gradually in the mitral group, in whom serial catheterisations show a gradual decrease in the pulmonary arterial and capillary pressure and an increase in the cardiac index which may be progressive until the second postoperative year. 4. Analysis of the mean values of the various parameters as a function of the clinical findings, and of the incidence of failures and early or late deaths from haemodynamic changes, has failed to show that the preoperative haemodynamic picture has a statistically significant predictive value.