Stellar structure and compact objects before 1940: Towards relativistic astrophysics

Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal

PowerPoint Slides for: 2MD (DP001), a Single Agent in the Management of Hemodialysis Patients: A Randomized Trial

<i>Background:</i> Vitamin D analogs and calcimimetics are used to manage secondary hyperparathyroidism (SHPT) in dialysis patients. DP001 is an oral vitamin D analog that suppresses parathyroid hormone (PTH) in uremic rats, osteopenic women, and hemodialysis patients. The safety and effectiveness of DP001 suppressing PTH in dialysis patients previously managed with active vitamin D with or without a calcimimetic are presented. <i>Methods:</i> A multicenter, randomized, double-blind study compared DP001 to placebo in hemodialysis patients with serum-intact PTH (iPTH) ≥300 pg/ml. The primary efficacy endpoint was the proportion of patients achieving 2 consecutive ≥30% decreases in iPTH levels during the 12 weeks of treatment. Calcium, phosphorus, calcium × phosphorus product and safety were also evaluated. The responses to DP001 were compared in patients previously treated with both active vitamin D and a calcimimetic to those previously on active vitamin D alone. <i>Results:</i> Sixty-two patients were randomized (n = 34 DP001; n = 28 placebo). At week 12, 78% of all DP001-treated patients and 7% of all placebo-treated patients achieved the primary endpoint (p < 0.0001); iPTH fell 45% in the DP001 group and increased 37% in the placebo group. No patient exceeded the safety threshold of 2 consecutively corrected serum calcium levels ≥11.0 mg/dl. Patients previously on cinacalcet plus active vitamin D also responded to DP001 (n = 10) resulting in a 55% decrease in iPTH, while those on placebo (n = 9) increased by 70%. <i>Conclusion:</i> DP001 safely and effectively suppressed iPTH in hemodialysis patients with SHPT that were previously managed with active vitamin D alone or with a calcimimetic (www.clinicaltrials.gov, NCT01922843)