ABSTRACT
JNCL is a neurodegenerative disease of childhood caused by mutations in the CLN3 gene. A mouse model for JNCL was created by disrupting exons 1-6 of Cln3, resulting in a null allele. Cln3 null mice appear clinically normal at 5 months of age; however, like JNCL patients, they exhibit intracellular accumulation of autofluorescent material. A second approach will generate mice in which exons 7 and 8 of Cln3 are deleted, mimicking the common mutation in JNCL patients.
Subject(s)
Cyclins , Disease Models, Animal , Neuronal Ceroid-Lipofuscinoses/genetics , Saccharomyces cerevisiae Proteins , Animals , Brain/anatomy & histology , Exons , Fluorescence , Fungal Proteins/metabolism , Gene Library , Gene Targeting , Humans , Membrane Glycoproteins/metabolism , Mice , Models, Genetic , Molecular Chaperones/metabolismABSTRACT
Moderately strong transverse-magnetic fields were used to modify conventional electron-dose distribution in tissue- and lung-equivalent phantoms. Magnetically modified symmetrical-isodose contours and central-axis depth-dose curves were measured for central fields in the range of 9--18 kG, field gradients of approximately 5 kG/cm, and accelerator energies of 10--45 MeV. To the extent that our experimental field strengths and gradients can be reproduced clinically, the measurements showed that magnetic distributions can be generated (in tissue) which are superior to conventional distributions for the treatment of tumors lying at depths less than approximately 7 cm provided that the tumor cross-section dimensions are equal to or greater than tumor depth. The surface dose in tissue is typically reduced by approximately 40% compared to the conventional surface dose for treating the same tumor volume. For the lung phantom data, a significant reduction (less than approximately 50%) in the integrated central-axis dose to healthy tissue was achieved for tumor depths of 10--14 cm. The possibility of reproducing our experimental magnetic fields and gradients inside a patient under realistic clinical conditions is discussed.
Subject(s)
Lung Neoplasms/radiotherapy , Magnetics , Models, Structural , Radiotherapy Dosage , Radiotherapy, High-Energy/methods , Humans , Lung/anatomy & histologyABSTRACT
We have measured the effect of a 10-kG magnetic field on the dose distribution of electrons in a polystyrene phantom. Isodensity plots and depth-dose curves are presented for 22- and 28-MeV electron beams with and without the magnetic field applied. The measurements show that magnetic fields as low as 10 kG can produce a substantial modification of the absorbed dose distribution. When compared with the zero-magnetic-field distribution of the same energy, the magnetic field significantly improves the Dmax- surface dose ratio and increases the fall off in dose past the Dmax region.