Neuroprotective effects of transcription factor Brn3b in an ocular hypertension rat model of glaucoma.

PURPOSE: Glaucoma is an optic neuropathy commonly associated with elevated intraocular pressure (IOP), leading to optic nerve head (ONH) cupping, axon loss, and apoptosis of retinal ganglion cells (RGCs), which could ultimately result in blindness. Brn3b is a class-4 POU domain transcription factor that plays a key role in RGC development, axon outgrowth, and pathfinding. Previous studies suggest that a decrease in Brn3b levels occurs in animal models of glaucoma. The goal of this study was to determine if adeno-associated virus (AAV)-directed overexpression of the Brn3b protein could have neuroprotective effects following elevated IOP-mediated neurodegeneration. METHODS: Intraocular pressure was elevated in one eye of Brown Norway rats (Rattus norvegicus), following which the IOP-elevated eyes were intravitreally injected with AAV constructs encoding either the GFP (rAAV-CMV-GFP and rAAV-hsyn-GFP) or Brn3b (rAAV-CMV-Brn3b and rAAV-hsyn-Brn3b). Retina sections through the ONH were stained for synaptic plasticity markers and neuroprotection was assessed by RGC counts and visual acuity tests. RESULTS: Adeno-associated virus-mediated expression of the Brn3b protein in IOP-elevated rat eyes promoted an upregulation of growth associated protein-43 (GAP-43), actin binding LIM protein (abLIM) and acetylated α-tubulin (ac-Tuba) both posterior to the ONH and in RGCs. The RGC survival as well as axon integrity score were significantly improved in IOP-elevated rAAV-hsyn-Brn3b-injected rats compared with those of the IOP-elevated rAAV-hsyn-GFP- injected rats. Additionally, intravitreal rAAV-hsyn-Brn3b administration significantly restored the visual optomotor response in IOP-elevated rat eyes. CONCLUSIONS: Adeno-associated virus-mediated Brn3b protein expression may be a suitable approach for promoting neuroprotection in animal models of glaucoma.

The post-baccalaureate premedical certification program at the University of North Texas Health Science Center strengthens admission qualifications for entrance into medical school.

The Post-Baccalaureate (postbac) Premedical Certification Program at the University of North Texas Health Science Center provides an opportunity for individuals to enhance their credentials for entry into medical school by offering a challenging biomedical science core curriculum in graduate biochemistry, cell biology, physiology, and pharmacology. In addition, students (called postbacs) receive instruction in human gross anatomy, histology, and embryology with first-year medical students. More than 90% of the students accepted into the postbac program have applied to medical school previously but have been rejected by admission committees at least once, primarily because of low cognitive scores. In spring 2001, seven postbacs completed the program, of which only one was admitted into the Texas College of Osteopathic Medicine (TCOM), the medical school affiliated with the University of North Texas Health Science Center. Three postbacs went to other medical schools. Thirty-one completed the program by spring 2006, of whom 13 were admitted to TCOM, and eight to other medical schools. After six years, 101 postbacs have completed the program, and 70 have been accepted into medical schools. Postbacs admitted into TCOM have performed well compared with their medical school classmates. Overall, average scores for postbacs are above those of their medical school classmates. In addition, postbacs have taken class leadership positions, served as tutors and mentors, and have served as school ambassadors for new applicants. The postbac premedical program has proven to be very successful in preparing students for the rigors of a medical school curriculum by allowing these students to develop the skills and confidence necessary to compete.