Entry site neovascularization and vitreous cavity hemorrhage after diabetic vitrectomy. The predictive value of inner sclerostomy site ultrasonography.

OBJECTIVE: To assess the incidence of neovascularization of the inner sclerostomy wound and occurrence of postoperative vitreous cavity hemorrhage (POVCH) after vitrectomy for proliferative diabetic retinopathy (PDR). DESIGN: Consecutive prospective longitudinal clinical study. PARTICIPANTS: Seventy-three eyes (58 patients) undergoing primary vitrectomy for PDR. METHODS: Twenty-megahertz (MHz) high-resolution anterior segment ultrasonography was performed on all sclerostomy sites 2 months postoperatively and repeated at the time of any POVCH. The appearance of the inner sclerostomy wound was divided into 4 classes (normal, spheroidal, tent, and trapezoidal, representing entry site neovascularization). The occurrence, degree, and duration of POVCH and need for revision surgery with vitreous cavity washout (VCW) were recorded. Postoperative vitreous cavity hemorrhage was divided into 3 groups-namely, mild, moderate, and major. MAIN OUTCOME MEASURES: Inner sclerostomy wound appearance on ultrasonography, degree and timing of POVCH, and need for VCW. RESULTS: There were 15 eyes in total with POVCH (20%): one patient had a persistent POVCH that required VCW. Fourteen other eyes (19%) had recurrent POVCH. Four (28%) of these 14 eyes with recurrent POVCH were classified as mild and 3 (21%) moderate: all cleared spontaneously with no further intervention needed. None of these had a trapezoidal image. Seven of the 14 eyes with recurrent POVCH were classified as major. Five of these 7 eyes had a trapezoidal image at 2 months postoperatively, and 4 required VCW (5.5% of total no. of eyes in study). All patients with a trapezoidal image experienced some degree of recurrent vitreous cavity hemorrhage (P = 0.0000024). The odds ratio was approximately 330:1. There was a significant correlation between the severity of POVCH and entry site appearance on ultrasound. In the first year of follow-up, all patients requiring VCW after recurrent POVCH had a trapezoidal image present at 2 months postoperatively (P = 0.009). CONCLUSION: The appearance of a trapezoidal image on 20-MHz high-resolution anterior segment ultrasonography at a sclerostomy site after vitrectomy for PDR was highly correlated with the occurrence of nonclearing POVCH and need for VCW. Conversely, the absence of a trapezoidal image in patients with POVCH was associated with spontaneous hemorrhage clearance.

Recombinant adeno-associated virus vector-based gene transfer for defects in oxidative metabolism.

Defects in oxidative metabolism may be caused by mutations either in nuclear genes or in mitochondrial DNA (mtDNA). We tested the hypothesis that recombinant adeno-associated virus (rAAV) could be used to complement mtDNA mutations. AAV vector constructs were designed to express the reporter gene encoding green fluorescent protein (GFP), fused to a targeting presequence that directed GFP to be translocated into mitochondria. These vectors mediated expression of mitochondrial-localized GFP, as indicated by fluorescence microscopy and electron microscopy, in respiring human embryonic kidney 293 cells and nonrespiring mtDNA-deficient (rho 0) cells. However, when sequences encoding hydrophobic segments of proteins normally encoded by mtDNA were inserted between the presequence and GFP, mitochondrial import failed to occur. In similar experiments, a fusion was created between pyruvate dehydrogenase (PDH) E1 alpha subunit, a nuclear-encoded mitochondrial gene with its own targeting presequence, and GFP. With this construct, expression of GFP was observed in mitochondria in vitro and in vivo. We conclude that the hydrophobicity of mtDNA-encoded proteins limits their ability to be transported from the cytoplasm. However, rAAV-based gene therapy may hold promise for gene therapy of PDH deficiency, the most common biochemically proven cause of congenital lactic acidosis.