ABSTRACT
Four-dimensional computed tomography (4D-CT) requires breathing information from the patient, and for this, several systems are available. Testing of these systems, under realistic conditions, requires a phantom with a moving target and an expandable outer contour. An anthropomorphic phantom was developed to simulate patient breathing as well as lung tumor motion. Using the phantom, an optical camera system (GateCT) and a pressure sensor (AZ-733V) were simultaneously operated, and 4D-CTs were reconstructed with a Siemens CT using the provided local-amplitude-based sorting algorithm. The comparison of the tumor trajectories of both systems revealed discrepancies up to 9.7 mm. Breathing signal differences, such as baseline drift, temporal resolution and noise level were shown not to be the reason for this. Instead, the variability of the sampling interval and the accuracy of the sampling rate value written on the header of the GateCT-signal file were identified as the cause. Interpolation to regular sampling intervals and correction of the sampling rate to the actual value removed the observed discrepancies. Consistently, the introduction of sampling interval variability and inaccurate sampling rate values into the header of the AZ-733V file distorted the tumor trajectory for this system. These results underline the importance of testing new equipment thoroughly, especially if components of different manufacturers are combined.
Subject(s)
Four-Dimensional Computed Tomography/instrumentation , Phantoms, Imaging , Respiration , HumansABSTRACT
The phenotype and function of splenic DC populations from diabetes-prone NOD mice were characterized and compared to DC from diabetes-resistant strains in the presence or absence of Flt3 ligand (FL) treatment. NOD mice were found to have significantly fewer CD8alpha+ DC than both B10.BR and C57BL/6 mice, and this defect was reversed by FL treatment. Freshly isolated CD8alpha+ and CD8alpha- DC from all three strains were found to express similar levels of costimulatory molecules and this was similar in both FL-treated and untreated animals. IL-12 p40 production was significantly lower in purified CD11c+ DC from NOD mice compared to DC from C57BL/6 or B10.BR mice. CD8alpha+ DC isolated from NOD mice produced lower levels of IL-12p40 than CD8alpha+ DC from C57CBL/6 and this was dependent on the nature of the stimulus given. In contrast both CD8alpha+ and CD8alpha- DC from FL-treated mice produced high levels of IL-12p40 following activation, but only the CD8alpha- DC produced IL-12p70. Functionally, freshly isolated CD8alpha- DC were more stimulatory than CD8alpha+ DC in a primary allogeneic mixed lymphocyte reaction. However, DC maturation resulted in increased T cell stimulatory capacity for both DC subsets, and this pattern was seen in all strains. These results demonstrate significant differences in phenotype and function of splenic NOD CD8alpha+ DC, and further suggest that FL treatment may reverse some of these abnormalities.
Subject(s)
CD8 Antigens/immunology , Dendritic Cells/immunology , Spleen/immunology , Adjuvants, Immunologic , Animals , CD11c Antigen/immunology , CD4-Positive T-Lymphocytes/immunology , Cells, Cultured , Diabetes Mellitus, Type 1/immunology , Immunophenotyping/methods , Interferon-gamma/biosynthesis , Interleukin-12/biosynthesis , Interleukin-12 Subunit p40 , Lymphocyte Culture Test, Mixed/methods , Membrane Proteins/immunology , Mice , Mice, Inbred C57BL , Mice, Inbred NOD , Mice, Inbred Strains , Protein Subunits/biosynthesis , T-Lymphocytes/immunology , Tumor Necrosis Factor-alpha/immunologyABSTRACT
NOD mice spontaneously develop diabetes between 15 and 20 weeks of age, which is preceded by insulitis characterized by the infiltration of lymphocytes. Dendritic cells (DC) are among the first cells to infiltrate the islet and they have been implicated in the pathogenesis of the disease. Our work has been concerned with the detailed characterization of four distinct DC populations in NOD mice: two derived from bone marrow (BM) cells cultured in either granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4) or GM-CSF alone and two from the spleen of Flt3 ligand (Flt3L) -treated mice, isolated on the basis of CD8alpha expression. Phenotypic and functional differences between these DC subsets in NOD mice have been identified. In addition, we obtained a lower yield of NOD BM-derived DC and they expressed higher levels of cell-surface CD40 and IL-12 p40 mRNA than BM-derived DC from the diabetes-resistant strain, B10.BR. We have also investigated the ability of these DC populations to modulate the development and progression of diabetes in NOD mice.
