Chemoselective Polymerization Control: From Mixed-Monomer Feedstock to Copolymers

A novel chemoselective polymerization control yields predictable (co)polymer compositions from a mixture of monomers. Using a dizinc catalyst and a mixture of caprolactone, cyclohexene oxide, and carbon dioxide enables the selective preparation of either polyesters or polycarbonates or copoly(ester-carbonates). The selectivity depends on the nature of the zinc–oxygen functionality at the growing polymer chain end, and can be controlled by the addition of exogeneous switch reagents

Macular thickness changes in a patient with Leber's hereditary optic neuropathy

Background: Leber's hereditary optic neuropathy (LHON) refers to an optic nerve dysfunction due to mutations in the mitochondrial DNA, resulting in visual loss by apoptosis of retinal ganglion cells (RGC). In 20% of LHON cases, their fundus examination looks entirely normal at early stage. There are some reports regarding the circumpapillary retinal nerve fiber layer (cpRNFL) and the ganglion cell analysis around the macula in LHON patients and carriers by using optical coherence tomography. Case presentation: A 40-year-old female complained of acute visual loss in both eyes. Her best-corrected visual acuity was 0.3 in the right eye and 0.2 in the left eye at the initial visit. Goldmann perimetry revealed bilateral central scotomas. Fundus examination and fluorescein angiography findings were normal, but decreased retinal inner layer thickness was detected around the macular area on spectral domain optical coherence tomography (SD-OCT). One month later, her visual acuity deteriorated to counting fingers in both eyes, and the thinning area of retinal inner layer spread rapidly. Suspected progressive RGC loss led us to check the possibility of LHON, with which the patient was diagnosed due to a positive result for the mitochondrial DNA (mtDNA) 11778 mutation. The ganglion cell complex (GCC) and cpRNFL thicknesses were observed for 24 months by using SD-OCT. The GCC thickness plunged sharply within 3 months followed by gradual decline until 6 months, thereafter showing a plateau up to 24 months. On the cpRNFL map, the temporal quadrant also showed the earliest thinning as seen in the macular area of the GCC map. The thicknesses of the superior, nasal, and inferior quadrants decreased gradually, keeping their normal ranges up to 6 months. Conclusions: SD-OCT was a useful tool in the diagnosis and follow-up of LHON. The macular GCC thickness map may detect the earliest morphological changes in LHON, as well as the temporal area of cpRNFL, before funduscopic examination reveals optic nerve atrophy

Sudden bilateral vision loss due to third ventricular cavernous angioma with intratumoral hemorrhage - case report

Background: We report a rare case of sudden bilateral vision loss due to third ventricular cavernous angioma with intratumoral hemorrhage. Case presentation: A 45-year-old woman presented decreased visual acuity in both eyes. Her best corrected visual acuity was 0.1 in the right eye and 0.15 in the left eye. Goldmann perimetry showed bilateral central scotomas and bitemporal visual field defects. MRI demonstrated a lesion with mixed hypo- and hyperintensity at the optic chiasm, which was thought to be an intratumoral hemorrhage. The patient underwent bifrontal craniotomy. The tumor was exposed via an anterior interhemispheric approach, and histological evaluation of the mass led to a diagnosis of cavernous angioma. Six months after the surgery, her best corrected visual acuity was 0.9 in the right eye and 0.9 in the left, with slight bitemporal visual field defects. Conclusion: Third ventricular cavernous angioma is considered in the differential diagnosis of chiasmal syndrome. Contrast-enhanced MRI and FDG-PET might be useful for differential diagnosis of cavernous angioma from other chiasmal tumors including glioblastoma