Various media and Ca2+ concentrations are employed to culture neural progenitor cells (NPCs). We have therefore explored the effects of extracellular calcium concentrations on the survival, proliferation, spontaneous apoptosis and self-renewal capacity of mesencephalic NPCs grown adherently and as free-floating neurospheres. We employed EMEM supplemented with various concentrations of extracellular CaCl2 (0.1-1 mM). Raising the calcium concentration from 0.1 mM to 0.6 mM resulted in an increased number of NPCs growing as a monolayer and increased the protein yield of cells growing in neurospheres (24+/-3 microg total proteins in 0.1 mM Ca2+ medium vs. 316+/-34 microg proteins in 1 mM Ca2+ medium). Concentrations more than 0.6 mM did not result in a further improvement of proliferation or survival. Elimination of calcium from our control medium by 1 mM EGTA resulted in a decrease in cell number from 82+/-2 x 10(4) NPCs/ml observed in control medium to 62+/-2 x 10(4) NPCs/ml observed in calcium-free media. Protein yield dropped significantly in calcium-free media, accompanied by the decreased expression of the proliferation marker PCNA and the pro-survival marker Bcl-2. Two weeks of expansion as neurospheres caused spontaneous cell death in more than 90% of NPCs grown in 0.1 mM CaCl2 EMEM compared with 42% in 1 mM CaCl2 EMEM. Although the action of Ca2+ on NPCs appears to be complex, the presented data strongly suggest that extracellular calcium plays a crucial role in the maintenance of NPCs in a healthy and proliferating state; physiological concentrations (>1.0 mM) are not required, a concentration of 0.5 mM being adequate for cell maintenance.

Snapping scapula syndrome represents a rare entity in shoulder surgery. Clinically, it presents as shoulder pain and loud crepitus during shoulder movement. Moreover, glenohumeral bursitis can cause additional pain. Snapping scapula syndrome is caused by an increased angulation of the superomedial part of the scapula combined with bursitis. Other common causes such as subscapular osteochondroma or rib fracture non-unions were excluded. We report a 24-year-old female patient with persisting shoulder pain and disturbing crepitus during movement of the left shoulder. Radiographic examination revealed increased angulation of the superomedial scapula on both sides and MRI, bursitis of the left shoulder. The patient was successfully treated with minimally invasive arthroscopic trimming of the prominent osseous formation at the left scapula combined with bursectomy. Additionally, specific pain-adapted physiotherapeutic exercises of both shoulders were performed. The patient had a pain-free shoulder movement without crepitus on both sides at the 6th month follow-up.

Ochronosis (arthropathia ochronotica) is a rare entity which can be identified by a visual diagnosis. Early diagnosis can provide crucial information for the prognosis. Additionally, an interdisciplinary treatment concept should be established because of the early onset of degenerative changes at the skeletal system and pathological changes at internal organs. With suspicion on an ochronosis extended internal examinations are recommended in order to avoid complications.

With respect to this case the high complication-rates in obese patients should be taken into account: Total knee replacement can even lead to loss of the limb in the worst case. In addition to extended preoperative examination this indication should be critically scrutinized.