Primary Spinal Cord Astrocytomas: Two-Center Clinical Experience of Low- and High-Grade Lesions.

OBJECTIVE: Primary spinal cord astrocytomas are rare, fatal, and poorly studied. METHODS: This study included a 2-center, retrospective analysis of primary spinal cord astrocytoma patients from 1997 to 2020. Patients with drop metastases or without at least one follow-up were excluded. RESULTS: Seven World Health Organization grade I, 6 grade II, 7 grade III, and 4 grade IV astrocytoma patients were included. Older patients had higher grades (median 20 years in grade I vs. 36.5 in grade IV). The median follow-up was 15 months. Thirteen patients were discharged to rehabilitation. Eight patients demonstrated radiographic progression. Adjuvant therapy was utilized more in higher grades (5 of 13 grades III vs. all 11 grades IIIIV). Six patients died (1 death in grades III vs. 5 in grades IIIIV). Ten patients had worsened symptoms at the last follow-up. The median progression-free survival in grade I, II, III, and IV tumors was 116, 36, 8, and 8.5 months, respectively. The median overall survival in grade I, II, III, and IV tumors was 142, 69, 19, and 12 months, respectively. Thrombotic complications occurred in 2 patients, one with isocitrate dehydrogenasewild type glioblastoma. CONCLUSIONS: Outcomes worsen with higher grades and lead to difficult postoperative periods. Clinicians should be vigilant for thromboembolic complications. Further research is needed to understand these rare tumors.

Optogenetic axon guidance in embryonic zebrafish.

Axons form the long-range connections of biological neuronal networks, which are built through the developmental process of axon guidance. Here, we describe a protocol to precisely and non-invasively control axonal growth trajectories in live zebrafish embryos using focal light activation of a photoactivatable Rac1. We outline techniques for photostimulation, time-lapse imaging, and immunohistochemistry. These approaches enable engineering of long-range axonal circuitry or repair of defective circuits in living zebrafish, despite a milieu of competing endogenous signals and repulsive barriers. For complete details on the use and execution of this protocol, please refer to Harris et al. (2020).