General Relativistic versus Newtonian: a universality in radiation hydrodynamics

We compare Newtonian and general relativistic descriptions of the stationary accretion of self-gravitating fluids onto compact bodies. Spherical symmetry and thin gas approximation are assumed. Luminosity depends, amongst other factors, on the temperature and the contribution of gas to the total mass, in both -- general relativistic ($L_{GR}$) and Newtonian ($L_N$) -- models. We discover a remarkable universal behaviour for transonic flows: the ratio of respective luminosities $L_{GR}/L_N$ is independent of the fractional mass of the gas and depends on asymptotic temperature. It is close to 1 in the regime of low asymptotic temperatures and can grow by one order of magnitude for high temperatures. These conclusions are valid for a wide range of polytropic equations of state.Comment: 8 pages, 4 figure

The influence of porcine pancreas digestion parameters and islet histomorphology on islet isolation outcome

Transplantation of the pig islets of Langerhans is considered as the future treatment for patients suffering from type I diabetes mellitus. Despite the adaptation of modified Ricordi method and highly purified collagenase, the results of pancreas digestions are precarious. Selection of proper donor and optimal digestion procedure are fundamental. The aim of this study was to assess the impact of pancreas procuring parameters on pig islets yield. The pancreata were harvested from 69 market sows weighting over 150 kg. After intraductal injection of cold collagenase solution pancreata were transported in UW solution or under conditions of two layer method (TLM). In laboratory pancreata were digested at 37℃ according to Ricordi isolation method or stationary in the bottle. The particular parameters of isolation procedure were considered as substantial. Pig weight, volume of infused collagenase solution, TLM application and pancreas dividing before digestion positively affected islet yield. Additionally, the influence of pancreatic islet tissue histomorphology on isolation outcome was studied. Proper donor selection as well as adequate digestion parameters could improve pig islet recovery during islet isolation

A Multicenter Study: North American Islet Donor Score in Donor Pancreas Selection for Human Islet Isolation for Transplantation

Selection of an optimal donor pancreas is the first key task for successful islet isolation. We conducted a retrospective multicenter study in 11 centers in North America to develop an islet donor scoring system using donor variables. The data set consisting of 1,056 deceased donors was used for development of scoring system to predict islet isolation success (defined as post-purification islet yield >400,000 islet equivalents). With an aid of univariate logistic regression analyses, we developed North American Islet Donor Score (NAIDS) ranging 0 through 100 points. The c-index in the development cohort was 0.73 [95% confidence interval 0.70 - 0.76]. The success rate increased proportionally as NAIDS increased, from 6.8% success in NAIDS < 50 points to 53.7% success in NAIDS ≥ 80 points. We further validated NAIDS using a separate set of data consisting of 179 islet isolations. Comparable outcome of NAIDS was observed in the validation cohort. The NAIDS may be a useful tool for donor pancreas selection in the clinical practice. Apart from its utility in clinical decision-making, the NAIDS may also be used in research setting as a standardized measurement of pancreas quality