Spinal changes after craniospinal irradiation in pediatric patients
PEDIATRIC BLOOD & CANCER
Authors: Oshiro, Yoshiko; Mizumoto, Masashi; Pan, Haitao; Kaste, Sue C.; Gajjar, Amar; Merchant, Thomas E.
Background To evaluate long-term degenerative changes in bone and soft tissue after craniospinal irradiation (CSI). Procedure An analysis was performed for 892 vertebral bodies in 220 pediatric patients treated with CSI. To analyze vertebral growth, vertebral body height was calculated. Signal changes for vertebral bodies on MRI, scoliosis and kyphosis, degenerative changes of vertebral bones and discs, and wedging or vertebral height loss were analyzed on images, and factors that influenced these changes were investigated. Results Vertebral growth was significantly correlated with radiation dose and growth hormone (GH) deficiency. Growth rate was significantly worse at a dose >39 Gy. Fatty marrow change was found in 83% of patients, 31% had disc degenerative changes, 13% had degenerative changes of spinal bones, 17% had wedging or spinal height loss, and 27% had scoliosis. Conclusions Vertebral bone growth was significantly reduced when high doses were administered, and adequate GH replacement was important for bone growth. Even with symmetrical irradiation, the risk of scoliosis is high after CSI. There was also frequent progression of spinal demineralization and degenerative changes after CSI. Therefore, careful attention should be paid to spinal symptoms as pediatric patients grow into adulthood.
A 200 nanoseconds all-atom simulation of the pH-dependent EF loop transition in bovine beta-lactoglobulin. The role of the orientation of the E89 side chain
JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS
Authors: Fenner, Kiara; Redgate, Arthur; Brancaleon, Lorenzo
In silicomolecular dynamics (MD) using crystallographic and NMR data was used to simulate the effects of the protonation state of E89 on the pH-dependent conformational rearrangement of the EF loop, also known as the Tanford transition, in a series of apo-beta-lactoglobulin (BLG) structures. Compared to existing studies these simulations were carried out over a much longer time scale (200 ns where the stability of the transition can be evaluated) and used an explicit water model. We considered eight different entries from the Brookhaven Protein Data Bank (PDB) separated into two groups. We observed that fixing the protonation state of E89 prompts the transition of the EF loop only when its side chain is oriented under the loop and into the entrance of the interior cavity. The motion of the EF loop occurs mostly as a step-function and its timing varies greatly from similar to 20 ns to similar to 170 ns from the beginning of the simulation. Once the transition is completed, the protein appears to reach a stable conformation as in a true two-state transition. We also observed novel findings. When the transition occurs, the hydrogen bond between E89 and S116 is replaced with a salt bridge with Lys residues in the beta C-CD loop-beta D motif. This electrostatic interaction causes the distortion of this motif as well as the protrusion of the GH loop into the aperture of the cavity with the result of limiting the increase of its contour area despite the rotation of the EF loop. Communicated by Ramaswamy H. Sarma