Fitting of magnetic susceptibility data as a function of temperature of various spin systems-a FORTRAN program

A FORTRAN program, SUSCEP.FOR, was developed for the fitting of the magnetic susceptibility curve measured as a function of temperature into a selected expression. It can be executed on an IBM PC compatible. The simplex method was used for least squares fit of a wide range of expressions for various spin systems. The calculated and observed susceptibility data are compared graphically for choosing initial values of unknown parameters and to examine the final fit. The input is given interactively through menus and the output is saved on disk file. Standard deviations of parameters are estimated. SUSCEP.FOR includes the following functions and the expressions resulted by linear combinations among them: (1) Curie law, (2) ions with zero-field splitting term (D) for 1≤ S ≤ 5/2, (3) Ising equation, (4) Bleaney-Bower equation, (5) magnetization equation for S = 1/2 dimer, (6) Bonner-Fisher equation, (7) modified Bonner-Fisher equation, (8) dimers with a variety of values for S1 and S2, (9) a few other selected functions from the literature, (10) a constant as a correction term. The program also considers molecular field correction for functions 2-9 and the Weiss constant for the Curie law. It provides a routine for user-specified function which can be modified to user requirements. Also there is provision to add more functions to enhance the capability. The program can handle up to 300 data points and 12 parameters. These limits can be increased if necessary by modifying the array dimensions

Hypoxia-induced post-translational changes in red blood cell protein map of newborns

Tyrosine (Tyr) phosphorylation is implicated in the modification of several erythrocyte functions, such as metabolic pathways and membrane transport, as well as in signal transduction systems. Here we describe the map of Tyr-phosphorylated soluble proteins of newborn red blood cells (RBC) using an in vitro model simulating RBC reoxygenation at birth after an intrauterine hypoxic event. We tested the hypothesis that a hypoxic environment and subsequent reoxygenation promote post-translational changes in the RBC protein map of newborns, in addition to desferrioxamine (DFO)-chelatable iron (DCI) release and methemoglobin (MetHb) formation. Umbilical cord blood RBC were incubated under hypoxic conditions for 16 h at 37 degrees C, and subsequently for 8 h under aerobic conditions. Control erythrocytes were incubated under aerobic conditions at 37 degrees C for the period of the experiment, i.e. for 24 h. Tyr-phosphorylation proteins were assessed using advanced high-resolution two-dimensional electrophoresis, 2-D immunoblot analysis with anti-phosphotyrosine (anti-pTyr) antibodies, and computer-aided electrophoretogram analysis. Higher DCI release and MetHb formation were observed in newborn RBC incubated under hypoxic conditions than in those incubated aerobically. Different immunoreactivity patterns with anti-pTyr antibodies were also observed between newborn RBC incubated under hypoxic conditions and controls. A hypoxic environment is a factor promoting DCI release, a well-known condition of oxidative stress. This is the first map of Tyr-phosphorylated soluble proteins of newborn RBC obtained using an in vitro model simulating RBC reoxygenation at birth after an intrauterine hypoxic event. Our results suggest that hypoxia increases Tyr-phosphorylation of antioxidant proteins, protecting RBC against oxidative stres