Doppler ultrasonography and computed tomography angiography demonstrate positional occlusion of vertebral artery associated with one-sided destruction of the atlantoaxial lateral mass caused by rheumatoid arthritis: a case report.

STUDY DESIGN: Case report of a patient with rheumatoid arthritis (RA) and a positional occlusion of the left vertebral artery (VA). OBJECTIVE: To describe the utility of Doppler ultrasonography and computed tomography (CT) angiography for the diagnosis of positional VA occlusion. SUMMARY OF BACKGROUND DATA: In previous reports of positional VA occlusion in RA, angiography has been used for the diagnosis. However, it is difficult to demonstrate the three-dimensional relationship between the arteries and the bone structure with angiography. METHODS: An 83-year-old man with a 20-year history of RA complained of severe vertigo when he leaned his head in the left-anterior direction. CT angiography in the neutral position revealed that the left VA was pinched between the posterior rim of the transverse foramen of C1 and the transverse process of C2. Doppler ultrasonography demonstrated positional VA occlusion and a severe reduction in blood flow at the position that most readily induces vertigo. Because the space between the transverse foramens of left C1 and C2 was reduced with the destruction of the left C1/C2 lateral masses, slight rotation, and anterior shift of C1 led to the occlusion of the VA. RESULTS: After posterior O-C2 fusion at the reduced position, the VA occlusion and vertigo disappeared. CONCLUSION: Doppler ultrasonography and CT angiography allow valuable measurements in the diagnosis of positional VA occlusion. The one-sided destruction of the C1/C2 lateral masses might be a causal factor for VA occlusion in RA. This is the first report of a new pathomechanism underlying positional VA occlusion demonstrated with three-dimensional CT angiography.

The telomere-specific non-LTR retrotransposons SART1 and TRAS1 are suppressed by Piwi subfamily proteins in the silkworm, Bombyx mori.

The telomere structures in Bombyx mori are thought to be maintained mainly by the transposition of the specialized telomeric retroelements SART and TRAS. The silkworm genome has telomeric TTAGG repeats and telomerase, but this telomerase displays little or no activity. Here, we report that the transcription of the telomeric retroelements SART1 and TRAS1 is suppressed by the silkworm Piwi subfamily proteins BmAgo3 and Siwi. The silkworm Piwi subfamily was found to be expressed predominantly in the gonads and early embryo, as in other model organisms, but in BmN4 cultured cells, these proteins formed granules that were separate from the nuage, which is a different behaviour pattern. The expression of TRAS1 was increased in BmN4 cells when BmAgo3 or Siwi were silenced by RNAi. Our results suggest that B. mori Piwi proteins are involved in regulating the transposition of telomeric retroelements, and that the functional piRNA pathway is conserved in BmN4 cultured cells.