Granulocyte Stimulating Factor Attenuates Hypoxic-ischemic Brain Injury by Inhibiting Apoptosis in Neonatal Rats

PURPOSE: This study was undertaken to determine the neuroprotective effect of granulocyte stimulating factor (G-CSF) on neonatal hypoxic-ischemic brain injury. MATERIALS AND METHODS: Seven-day-old male newborn rat pups were subjected to 110 minutes of 8% oxygen following a unilateral carotid artery ligation. Apoptosis was identified by performing terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining and flow cytometry with a combination of fluorescinated annexin V and propidium iodide (PI) and JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide). The extent of cerebral infarction was evaluated at 2 weeks after recovery. RESULTS: With a single dose (50microgram/kg) of G-CSF treatment immediately after hypoxic-ischemic insult, hypoxia-ischemia induced increase in TUNEL-positive cells, annexinV+/PI- and JC-1 positive apoptotic cells in the ipsilateral cerebral cortex was significantly reduced at 24 hours, measured by flow cytometry, and the extent of cerebral infarction at 2 weeks after recovery was also significantly attenuated compared to the hypoxia-ischemia control group. CONCLUSION: Our data suggest that G-CSF is neuroprotective by inhibiting apoptosis, thereby reducing the ensuing cerebral infarction in a newborn rat pup model of cerebral hypoxia-ischemia (HI).

The Optimal Time of First Ophthalmic Examination for Retinopathy of Prematurity Screening in Extremely Low Birth Weight Infants

PURPOSE: To determine the optimal time of first ophthalmic examination for early detection and proper treatment of retinopathy of prematurity (ROP) based on the chronological age or the postconceptional age. METHODS: Medical records of all extremely low birth weight infants(or=27 weeks). And we evaluated the time of first examination, the time of onset ROP, the time of peak stage and the time of threshold disease requiring cryotherapy or laser therapy. RESULTS: Among all 80 infant patients, 72 (90%) were found to have ROP. And 23 (29%) were treated for threshold disease with cryotherapy or laser therpy. There was no significant difference in incidence of ROP between two groups, and also no serious case of ROP was found. At time of first ophthalmic examination, onset ROP and threshold disease there was no difference of chronological age between two groups, but postconceptional age of Group II was considerably higher than Group I (P<0.05). CONCLUSION: ELBW infants less than 1,000 g should receive initial ROP screening using the chronological age guideline of 4 to 6 weeks rather than 31- to 33- week postconceptional age guideline.