[Adrenal crisis]. / Nebennierenkrise.

Patients with chronic adrenal insufficiency suffer from reduced quality of life and increased mortality. An association between mortality and adrenal crisis is assumed. The frequency of adrenal crisis is about 8/100 patient years. The main causes are infectious disease. Pathophysiology is poorly understood to date. An association with an exaggerated inflammatory response due to a lack of glucocorticoid modulation as well as mineralocorticoid deficiency and diminished adrenomedullary function are discussed. The therapy of adrenal crisis includes prompt parenteral administration of hydrocortisone combined with isotonic saline. To prevent adrenal crisis, patients are equipped with an emergency card and set and educated in glucocorticoid dose adjustment.

[Addison's disease : Primary adrenal insufficiency]. / Morbus Addison : Primäre Nebenniereninsuffizienz.

Adrenal insufficiency, a rare disorder which is characterized by the inadequate production or absence of adrenal hormones, may be classified as primary adrenal insufficiency in case of direct affection of the adrenal glands or secondary adrenal insufficiency, which is mostly due to pituitary or hypothalamic disease. Primary adrenal insufficiency affects 11 of 100,000 individuals. Clinical symptoms are mainly nonspecific and include fatigue, weight loss, and hypotension. The diagnostic test of choice is dynamic testing with synthetic ACTH. Patients suffering from chronic adrenal insufficiency require lifelong hormone supplementation. Education in dose adaption during physical and mental stress or emergency situations is essential to prevent life-threatening adrenal crises. Patients with adrenal insufficiency should carry an emergency card and emergency kit with them.

Phospholipase D is a central regulator of collagen I-induced cytoskeletal rearrangement and podosome formation in megakaryocytes.

BACKGROUND: Blood platelets are small anucleated cell fragments generated from bone marrow megakaryocytes (MKs) by a cytoskeleton-driven process. Thereby, mature MKs form long cytoplasmic protrusions (pro-platelets), which extend into the sinusoids within the bone marrow and finally release platelets. Podosomes are F-actin rich matrix contacts that have been suggested to play an important role in cell migration, but also in pro-platelet formation by MKs. Phospholipase D (PLD) has been proposed to contribute to the regulation of actin dynamics through the local generation of phosphatidic acid but its role in platelet formation is unknown. OBJECTIVE: We sought to investigate the significance of PLD in MK podosome formation and thrombocytopoiesis. METHODS: Podosome formation, spreading and ultra-structure of PLD single- and double-deficient MKs were analyzed using confocal and transmission electron microscopy. RESULTS: Phospholipase D-deficient MKs displayed a highly altered ultra-structure in vivo and abnormal actin rearrangement, with almost abolished formation of podosomes upon spreading on collagen I in vitro. However, MK endomitosis and platelet production were not altered by PLD deficiency. CONCLUSION: Together, our findings point to a specific function of PLD in actin dynamics as well as podosome formation and size determination in MKs on a collagen I matrix. The normal platelet number in PLD-deficient mice, however, suggests the existence of compensatory mechanisms in vivo that overcome the defective podosome formation observed in vitro.