A 4πγ integral counting system with a NaI(Tl) well-type detector and a digital interface to acquire measurement data was implemented at LMR-CNEA. The detection efficiency as a function of the energy ...was computed by Monte Carlo simulations and the total efficiencies for ampoules and point sources were calculated considering all the decay branches. A computer code was developed to analyse data. This program reads the files generated by the digitizer module, corrects for dead time and calculates source activities and their uncertainties. Ampoules with solutions of 113Sn, 192Ir and 131I were measured.
•Implementation of a new measurement system at LMR-CNEA (Argentina).•Based on a well-type NaI(Tl) detector.•Instruments, methods and uncertainty budget are detailed.
The nuclide
241Am decays by alpha emission to
237Np. Most of the decays (84.6%) populate the excited level of
237Np with energy of 59.54
keV. Digital coincidence counting was applied to standardize a ...solution of
241Am by alpha–gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.
A non-radionuclide-specific computer code to analyze data, calculate detection efficiency and activity in a TDCR system is presented. The program was developed prioritizing flexibility in measuring ...conditions, parameters and calculation models. It is also intended to be well structured in order to easily replace subroutines which could eventually be improved by the user. It is written in standard FORTRAN language but a graphical interface is also available. Several tests were performed to check the ability of the code to deal with different decay schemes such as H-3, C-14, Fe-55, Mn-54 and Co-60.
This work presents the experience developed by the Radioisotope Metrology Laboratory (LMR), of the Argentine National Atomic Energy Commission (CNEA), as result of the accreditation process of the ...Quality System by ISO 17025 Standard. Considering the LMR as a calibration laboratory, services of secondary activity determinations and calibration of activimeters used in Nuclear Medicine were accredited. A peer review of the
(
α
/
β
)
-
γ
coincidence system was also carried out. This work shows in detail the structure of the quality system, the results of the accrediting audit and gives the number of non-conformities detected and of observations made which have all been resolved.
The nuclide 18F disintegrates to 18O by beta+ emission (96.86%) and electron capture (3.14%) with a half-life of 1.8288 h. It is widely used in nuclear medicine for positron emission tomography ...(PET). Because of its short half-life this nuclide requires the development of fast measuring methods to be standardized. The combination of LSC methods with digital techniques proves to be a good alternative to get low uncertainties for this, and other, short lived nuclides. A radioactive solution of 18F has been standardized by coincidence counting with a LSC, using the logical sum of double coincidences in a TDCR array and a NaI scintillation detector. The results show good consistency with other techniques like 4Pi gamma and LSC.
The nuclide 241Am decays by alpha emission to 237Np. Most of the decays (84.6 %) populate the excited level of 237Np with energy of 59.54 keV. Digital Coincidence Counting was applied to standardize ...a solution of 241Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid Scintillation Counting using the logical sum of double coincidences in a TDCR array and Defined Solid Angle Counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.
Frente a una infección por Helicobacter pylori (H. pylori), el huésped desarrolla una respuesta inmune que es inefectiva en eliminar la bacteria. El sistema inmune innato, juega un rol central ...procesando y presentando antígenos de H. pylori. La presencia de citoquinas reguladoras (IL-10 o IL-12) podrían modular una respuesta linfocítica (Th) tipo 1 estableciendo una gastritis crónica, o una respuesta Th2 con producción de anticuerpos y la erradicación de la bacteria. IFN-gamma (respuesta Th1) podría mediar la inducción y la expresión de proteínas que pertenecen al complejo de histocompatibilidad tipo II (HLA-II) en células epiteliales, aumentando la adherencia de H. pylori al epitelio gástrico e induciendo apoptosis. IL-4 (respuesta Th2) podría aumentar la expresión del HLA-II, la producción de IgG e IgE, el crecimiento de células T. Finalmente estudios recientes se han focalizado en la inducción de apoptosis celular como un mecanismo de proliferación celular balanceada y como método de defensa del huésped frente a la infección por H. pylori
Highlights ► We assessed prevalence of intracranial atherosclerosis among stroke-free Caucasians. ► We found a prevalence of 8.6% in a population with moderate-high vascular risk. ► Diabetes and age ...were independently associated with this condition.
MYC alterations influence the survival of patients with diffuse large B-cell lymphoma. Most studies have focused on MYC translocations but there is little information regarding the impact of ...numerical alterations and protein expression. We analyzed the genetic alterations and protein expression of MYC, BCL2, BCL6, and MALT1 in 219 cases of diffuse large B-cell lymphoma. MYC rearrangement occurred as the sole abnormality (MYC single-hit) in 3% of cases, MYC and concurrent BCL2 and/or BCL6 rearrangements (MYC double/triple-hit) in 4%, MYC amplifications in 2% and MYC gains in 19%. MYC single-hit, MYC double/triple-hit and MYC amplifications, but not MYC gains or other gene rearrangements, were associated with unfavorable progression-free survival and overall survival. MYC protein expression, evaluated using computerized image analysis, captured the unfavorable prognosis of MYC translocations/amplifications and identified an additional subset of patients without gene alterations but with similar poor prognosis. Patients with tumors expressing both MYC/BCL2 had the worst prognosis, whereas those with double-negative tumors had the best outcome. High MYC expression was associated with shorter overall survival irrespectively of the International Prognostic Index and BCL2 expression. In conclusion, MYC protein expression identifies a subset of diffuse large B-cell lymphoma with very poor prognosis independently of gene alterations and other prognostic parameters.
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