Radiotherapy for thyroid orbitopathy. Effects on extraocular muscle balance.

OBJECTIVE: To investigate the effects of radiotherapy on the restrictive ophthalmopathy and strabismus that occur with Graves' orbitopathy. DESIGN: A prospective study of patients with motility disturbances due to thyroid orbitopathy, followed by serial quantitative measurements of ocular restrictions and deviations, both before and at 1 and 6 months after treatment with high-energy radiotherapy. SETTING: Urban subspecialty private practice. PATIENTS: Thirty-three consecutive patients with restricted extraocular movements and diplopia secondary to thyroid orbitopathy who were treated with radiotherapy were seen during an 8-year period. MEASURES: Maximal horizontal and vertical ductions, plus ocular deviations in primary and reading positions of gaze, were quantitatively evaluated by one clinical investigator to ensure consistency. RESULTS: Statistically significant improvement in gaze restriction on supraduction and improvement of vertical and horizontal strabismus were demonstrated at follow-up visits after treatment. CONCLUSIONS: Although statistically significant improvement of motility disturbances were demonstrated after radiotherapy, there was less than desirable functional improvement of restrictive ophthalmopathy and strabismus; thus the usefulness of radiotherapy was limited when it was used alone to treat diplopia.

Release of cell-free ice nuclei by Erwinia herbicola.

Several ice-nucleating bacterial strains, including Erwinia herbicola, Pseudomonas fluorescens, and Pseudomonas syringae isolates, were examined for their ability to shed ice nuclei into the growth medium. Only E. herbicola isolates shed cell-free ice nuclei active at -2 to -10 degrees C. These cell-free nuclei exhibited a freezing spectrum similar to that of ice nuclei found on whole cells, both above and below -5 degrees C. Partially purified cell-free nuclei were examined by density gradient centrifugation, chemical and enzymatic probes, and electron microscopy. Ice-nucleating activity in these cell-free preparations was associated with outer membrane vesicles shed by cells and was sensitive to protein-modifying reagents.