Pericardium of the frog, Rana esculenta, is morphologically designed as a lymphatic space

The Amphibian Heart

Currently, there are more than 8200 amphibian species described, including the orders Anura (frogs and toads), Caudata (salamanders and newts) and Gymnophiona (caecilians). Amphibians have 3 heart chambers: 2 atria and 1 ventricle. Their heart anatomy, histology, and physiology are reviewed. The basic morphology of the heart is similar in all amphibians with some differences due to their lifestyle. Blood flow, blood mixing, and blood oxygenation show variation due to interindividual and interspecific differences. Finally, different diagnostic methods to investigate the amphibian heart are described and reported amphibian heart diseases are summarized, including genetic, congenital, infectious, and neoplastic heart diseases.

Increased Level of Pericardial Insulin-Like Growth Factor-1 in Patients With Left Ventricular Dysfunction and Advanced Heart Failure

OBJECTIVES

To test the hypothesis that the cardiac insulin-like growth factor-1 (IGF-1) system is up-regulated in the failing heart, we measured the pericardial (cardiac) and plasma (circulating) IGF-1 levels in coronary artery disease patients.

BACKGROUND

Local IGF-1 systems are regulated differently from the systemic IGF-1 system. The cardiac IGF-1 system is up-regulated by the increased left ventricular (LV) wall stress. However, it remains unknown how this system is affected in LV dysfunction and heart failure.

METHODS

We measured the plasma and pericardial fluid levels of IGF-1 and brain natriuretic peptide (BNP) in 87 coronary artery disease patients undergoing cardiac surgery, and examined their relationships with LV function and heart failure severity. The expressions of IGF-1 and IGF-1 receptor proteins were examined in endomyocardial biopsies obtained from other patients with normal or impaired LV function.

RESULTS

The pericardial IGF-1 and BNP levels were positively correlated with the plasma BNP level (both p < 0.001). The pericardial IGF-1 level was increased in heart failure patients, whereas the plasma IGF-1 level was rather decreased. The pericardial IGF-1 level was inversely correlated with the LV ejection fraction (p < 0.001), whereas the plasma IGF-1 level was not. Positive immunostaining for IGF-1 and IGF-1 receptor proteins was enhanced in myocardial biopsies from failing hearts compared with those from nonfailing hearts.

CONCLUSIONS

The pericardial IGF-1 level was increased in patients with LV dysfunction and heart failure, whereas the plasma IGF-1 level was decreased. These results may indicate that up-regulation of the cardiac IGF-1 system serves as a compensatory mechanism for LV dysfunction.

Cardiac morpho-dynamics in Rana esculenta: Influence of sex and season

Morpho-dynamic aspects of the frog (Rana esculenta) heart were correlated to seasonal and sexual traits. The statistical analysis of the data (696 frog specimens: 448 males and 248 females), collected during 8 years of routine research on frog cardiac physiology, indicated that cardiac biology is characterised by sexual dimorphism. The relative cardiac weight of males was higher than that of females of similar size. With respect to the males of similar size, female frogs revealed an increased relative ventricular weight and ventricular contractile capacity. The morphometric analysis showed that the ventricular growth was achieved through significant myocardial enlargement accompanied by a reduction of the lacunary spaces. This is more pronounced in females during the breeding period. The correlation between sexual maturity and ventricular morpho-functional changes revealed that in male frogs sexual maturity correlates with a remarkable increment of the ventricular weight associated with higher values of pulse pressure. This data indicate that sex and season-related factors influence cardiac morpho-dynamics in R. esculenta.

Development of the lymphatic vascular system: a mystery unravels

The blood vascular and the lymphatic system play complementary roles in tissue perfusion and fluid reabsorption. Despite its critical role in mediating tissue fluid homeostasis, intestinal lipid absorption, and the immune response, the lymphatic system has not received as much attention as the blood vascular system, largely due to a lack of lymphatic-specific markers and to the dearth of knowledge about the molecular regulation of lymphatic development and function. A series of recent landmark studies now significantly has advanced our understanding of the lymphatic system. Based upon the discovery and characterization of lymphatic-specific growth factors, receptors, and transcriptional regulators, the mystery of lymphatic vascular system development begins to be unraveled. The successful isolation and cultivation of blood vascular and lymphatic endothelial cells has enabled comparative molecular and cellular analyses of these two genetically and developmentally closely related cell lineages. Moreover, studies of several genetic mouse models have set the framework for a new molecular model of embryonic lymphatic vascular development and have identified molecular pathways whose mutational inactivation leads to human diseases associated with lymphedema. Although these rapid advances already have led to development of the first lymphatic-targeted molecular therapies, there still remain many unanswered questions regarding almost every aspect of lymphatic vascular biology, making the lymphatic system a highly exciting and rewarding field of study.