Simulation study of accelerator based quasi-mono-energetic epithermal neutron beams for BNCT

Filtered neutron techniques were applied to produce quasi-mono-energetic neutron beams in the energy range of 1.5-7.5 keV at the accelerator port using the generated neutron spectrum from a Li (p, n) Be reaction. A simulation study was performed to characterize the filter components and transmitted beam lines. The feature of the filtered beams is detailed in terms of optimal thickness of the primary and additive components. A computer code named "QMNB-AS" was developed to carry out the required calculations. The filtered neutron beams had high purity and intensity with low contamination from the accompanying thermal, fast neutrons and γ-rays.

Immunoglobulin Class (IgG, IgM) Determination by Dithiothreitol in Sensitized Kidney Transplant Candidates

Immunoglobulin class plays an important role in the histocompatibility crossmatch test to predict hyperacute rejection in kidney transplantation. The existing data indicates that immunoglobulin (Ig) M antibodies, particularly when they are autoantibodies, are not deleterious to the renal allograft. We used the reducing agent dithiotreitol (DTT) to inactivate IgM but not IgG in the crossmatch assay to help sensitized patients have the chance for successful transplantation. In this descriptive study, 57 candidates for kidney transplantation with final positive crossmatches who had a history of panel-reactive antibody (PRA) greater than 30% were selected. Two of 57 patients had systemic lupus erythematous (SLE). The sera of patients were treated by DTT and then measured for cytotoxicity against donor lymphocytes and a panel of 12 cells using the complement-dependent cytotoxicity (CDC) method. Autocrossmatch was also performed to differentiate autoantibodies and alloantibodies by the CDC method. Of the 57 patients, six subjects (10.53%) had IgM and 51 patients (89.47%) IgG in their serum against donor lymphocytes. Also against panel cells, 39 of 57 patients (68.43%) had IgG, three patients (5.26%) had IgM, and 15 patients (26.31%) had both IgG and IgM antibodies. Autolymphocytotoxic antibodies were detected in 1.75% patients (1 of 57) who had SLE. According to our results, 5.26% of the patients who were IgM-positive and IgG-negative for both crossmatch and PRA assays may experience successful kidney transplantation.

Application of 8-amino-N-(2-hydroxybenzylidene)naphthyl amine as a neutral ionophore in the construction of a lanthanum ion-selective sensor

In this work, a novel La(III) membrane sensor based on 8-amino-N-(2-hydroxybenzylidene)naphthylamine (AIP) is presented. This electrode reveals good selectivity for La(3+) over a wide variety of lanthanides metal ions. Theoretical calculations and conductance study of AIP to lanthanum and some other metal ions were carried out and confirmed selectivity toward La(III) ions. The electrode comprises 7% AIP, 30% PVC, 61% NPOE and 2% KTpClPB. The sensor displays a linear dynamic range between 1.0 x 10(-7) and 1.0 x 10(-1) M, with a nice Nernstian slope of 20.3+/-0.3 mV per decade and a detection limit of 8.0 x 10(-8) M. The potentiometric response is independent of pH in the range of 4.0-9.0. The proposed sensor posses the advantage of short response time, and especially, very good selectivity towards a large number of cations, such as Sm(III), Ce(III, Pr(III), Yb(III) and Hg(II), low detection limit and wide linear dynamic range in comparison with former ones. The electrode can be used for at least seven weeks without any considerable divergence in the potentials. It was used as an indicator electrode in the potentiometric titration of La(III) ions with EDTA. The sensor was applied to the determination of La(III) ions concentration in binary mixtures. It was also applied for the determination of fluoride ions in mouth wash preparations.

Peripheral neuropathy in systemic lupus erythematosus in Southern Iran

The prevalence of clinically apparent peripheral neuropathy in systemic lupus erythematosus (SLE) is reported to be between 2-27%. The purpose of this descriptive cross sectional study was to determine the prevalence of peripheral neuropathy (PN) using electrodiangostic criteria in SLE in southern Iran. Subgroup analysis was performed to determine whether PN correlated with disease activity, serum immune markers and duration of disease and clinical findings. The right median, ulnar, peroneal, tibial and sural sensory and motor nerve conduction studies were conducted in 64 SLE cases. PN in our study was defined as any abnormal values in sensory action potential, motor action potential, or conduction velocity affecting 2 or more nerves. Of 64 patients studied, PN was present in 12 patients (18.7%), of which 4 (6.6%) were symptomatic. There was no significant correlation between PN and serum immune markers, and there was a trend showing decreased motor and sensory action potential amplitude in our SLE group compared to the controls. This observation was also seen in active disease group where compared to inactive disease. The amplitude of the action potential and then NCV were more often affected than distal latency, and sensory nerves were more susceptible than motor nerves and regarding the results electrodiognostic study is more sensitive than clinical evidence in detecting PN in SLE.

Monte Carlo simulation of x-ray spectra in diagnostic radiology and mammography using MCNP4C

The general purpose Monte Carlo N-particle radiation transport computer code (MCNP4C) was used for the simulation of x-ray spectra in diagnostic radiology and mammography. The electrons were transported until they slow down and stop in the target. Both bremsstrahlung and characteristic x-ray production were considered in this work. We focus on the simulation of various target/filter combinations to investigate the effect of tube voltage, target material and filter thickness on x-ray spectra in the diagnostic radiology and mammography energy ranges. The simulated x-ray spectra were compared with experimental measurements and spectra calculated by IPEM report number 78. In addition, the anode heel effect and off-axis x-ray spectra were assessed for different anode angles and target materials and the results were compared with EGS4-based Monte Carlo simulations and measured data. Quantitative evaluation of the differences between our Monte Carlo simulated and comparison spectra was performed using student's t-test statistical analysis. Generally, there is a good agreement between the simulated x-ray and comparison spectra, although there are systematic differences between the simulated and reference spectra especially in the K-characteristic x-rays intensity. Nevertheless, no statistically significant differences have been observed between IPEM spectra and the simulated spectra. It has been shown that the difference between MCNP simulated spectra and IPEM spectra in the low energy range is the result of the overestimation of characteristic photons following the normalization procedure. The transmission curves produced by MCNP4C have good agreement with the IPEM report especially for tube voltages of 50 kV and 80 kV. The systematic discrepancy for higher tube voltages is the result of systematic differences between the corresponding spectra.

IgG autoantibody activity in normal mouse serum is controlled by IgM

In the serum of normal BALB/c mice, IgG antibody reactivity to mouse actin and tubulin, DNA, and TNP groups was very low compared to that of the IgM. This activity was considerably increased when IgG was separated, by affinity chromatography on protein A-Sepharose, whereas no difference in the IgM activity was observed. Addition of IgM to IgG isolated from the same serum resulted in the inhibition of IgG binding to these Ag. Isolation of IgG antibodies on actin, TNP, and tubulin immunoadsorbents has indicated that at least part of the IgG antibodies is polyreactive. In order to understand this inhibition better, experiments with F(ab')2 fragments of IgG were performed. IgM inhibited the binding of F(ab')2 to the antigens in a dose-dependent manner and reacted with immobilized F(ab')2. IgM isolated on F(ab')2 immunoadsorbent, as compared to the initial IgM preparation, were less active toward the Ag but more inhibitory for IgG binding to the Ag. In some pathologic situations, IgM failed to inhibit some IgG antibody activities. The anti-DNA IgG activity from (NZB x NZW)F1 mice was not affected by autologous IgM. Similarly the anti-tubulin IgG from mice infected with Trypanosoma cruzi were less inhibited by IgM from autologous serum than antitubulin IgG from normal mice. These results are compatible with the existence in normal mice of an idiotypic-like network, regulating via an IgM population in the serum, the binding of IgG autoantibodies to self Ag. Modifications of this idiotype-anti-idiotype system might lead to the expression and/or expansion of autoreactive IgG-producing clones.

IgG autoantibody activity in normal mouse serum is controlled by IgM

In the serum of normal BALB/c mice, IgG antibody reactivity to mouse actin and tubulin, DNA, and TNP groups was very low compared to that of the IgM. This activity was considerably increased when IgG was separated, by affinity chromatography on protein A-Sepharose, whereas no difference in the IgM activity was observed. Addition of IgM to IgG isolated from the same serum resulted in the inhibition of IgG binding to these Ag. Isolation of IgG antibodies on actin, TNP, and tubulin immunoadsorbents has indicated that at least part of the IgG antibodies is polyreactive. In order to understand this inhibition better, experiments with F(ab')2 fragments of IgG were performed. IgM inhibited the binding of F(ab')2 to the antigens in a dose-dependent manner and reacted with immobilized F(ab')2. IgM isolated on F(ab')2 immunoadsorbent, as compared to the initial IgM preparation, were less active toward the Ag but more inhibitory for IgG binding to the Ag. In some pathologic situations, IgM failed to inhibit some IgG antibody activities. The anti-DNA IgG activity from (NZB x NZW)F1 mice was not affected by autologous IgM. Similarly the anti-tubulin IgG from mice infected with Trypanosoma cruzi were less inhibited by IgM from autologous serum than antitubulin IgG from normal mice. These results are compatible with the existence in normal mice of an idiotypic-like network, regulating via an IgM population in the serum, the binding of IgG autoantibodies to self Ag. Modifications of this idiotype-anti-idiotype system might lead to the expression and/or expansion of autoreactive IgG-producing clones.