Despite increasing evidence that supports the role of different post-translational modifications (PTMs) in modulating α-synuclein (α-syn) aggregation and toxicity, relatively little is known about the functional consequences of each modification and whether or not these modifications are regulated by each other. This lack of knowledge arises primarily from the current lack of tools and methodologies for the site-specific introduction of PTMs in α-syn. More specifically, the kinases that mediate selective and efficient phosphorylation of C-terminal tyrosine residues of α-syn remain to be identified. Unlike phospho-serine and phospho-threonine residues, which in some cases can be mimicked by serine/threonine → glutamate or aspartate substitutions, there are no natural amino acids that can mimic phospho-tyrosine. To address these challenges, we developed a general and efficient semisynthetic strategy that enables the site-specific introduction of single or multiple PTMs and the preparation of homogeneously C-terminal modified forms of α-syn in milligram quantities. These advances have allowed us to investigate, for the first time, the effects of selective phosphorylation at Y125 on the structure, aggregation, membrane binding, and subcellular localization of α-syn. The development of semisynthetic methods for the site-specific introduction of single or PTMs represents an important advance toward determining the roles of such modifications in α-syn structure, aggregation, and functions in heath and disease.

Clinical data suggest a role for VEGF in uveitic cystoid macular oedema (CME), even though the data on intravitreal VEGF levels in these eyes is still inconclusive. We determined intravitreal VEGF levels and treated uveitis patients with intravitreal bevacizumab.
Intravitreal VEGF levels were measured in eight uveitis patients and 10 controls using cytometric bead array technology. In 11 eyes of a second group of uveitis patients, CME was treated using 1.25 mg bevacizumab intravitreally. Re-injections of bevacizumab were given in patients showing a transient positive effect, defined as an increase of the best-corrected vision of at least two lines on a snellen chart. Alternatively, triamcinolone was given in patients, not responding to bevacizumab.
Mean intravitreal VEGF concentration was 82.75+/-171.71 pg/ml (+/-SD) (range, 0.0-502.1 pg/ml), and below the detection levels in controls. A significant reduction of retinal thickness was seen at weeks 2 (P=0.001) and 4 (P=0.007). A significant improvement in VA was seen at week 2 (P=0.02). Patients presenting with a CME in baseline fluorescein-angiogram responded well towards bevacizumab treatment, unless an extensive leakage from the choroid or a leakage of the optic disk was detectable. In these patients, only intravitreally administered triamcinolone led to a reduction of the CME.
Our data suggest that patients presenting with a diffuse leakage from the choroid in the fluorescein angiogram or an extensive leakage of the optic disk should be treated with intravitreal triamcinolone, whereas in patients presenting only a cystoid macular oedema bevacizumab treatment seems like a good choice.

To investigate the role of inflammatory and angiogenic factors in the pathogenesis of diabetic retinopathy, we determined, in diabetic patients and controls, vitreous and serum concentrations of interferon-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, regulated upon activation, normal T-expressed and secreted (RANTES), and vascular endothelial growth factor (VEGF).
We recruited 36 probands with type 2 diabetes mellitus (15 noninsulin-dependent and 21 insulin-dependent) and 69 normal controls. Using Cytometric Bead Array Technology, we measured vitreous and serum concentrations of IP-10, MCP-1, MIP-1alpha, MIP-1beta, RANTES, and VEGF.
In diabetic patients the mean vitreous levels of IP-10, MCP-1 and VEGF were significantly higher compared normal controls. [IP-10 (pg/mL) 254.84 +/-311.67 versus 78.90 +/- 67.94 (p<0.001); MCP-1 (pg/mL) 1127.14 +/- 738.91 versus 700.80 +/-419.21 (p=0.002); VEGF (pg/mL) 954.98 +/- 2315.09 versus 37.90 +/- 28.51(p<0.001)]. Vitreous levels of VEGF correlated with vitreous levels of both IP-10 and MCP-1 (p<0.05). MIP-1beta, RANTES, and VEGF mean serum levels were significantly raised in diabetic probands while IP-10, MCP-1, and MIP-1alpha serum levels showed no significant elevation compared to controls [IP-10 (pg/mL) 346.20 +/- 287.36 versus 328.74 +/-352.35 (p=0.88); MCP-1(pg/mL) 133.10 +/- 89.10 versus 141.47 +/- 222.15 (p=0.50); MIP-1beta (pg/mL) 184.40 +/- 100.20 versus 139.56 +/- 151.38 (p=0.003); RANTES (pg/mL) 51336.23 +/- 19940.31 versus 33629.2 +/- 33301.0 (p=0.002); VEGF (pg/mL) 304.88 +/- 257.52 versus 154.45 +/- 114.78 (p<0.001)].
Our results suggest that in diabetics, there is an upregulation of IP-10, MCP-1, and VEGF in the vitreous and an upregulation of MIP-1beta, RANTES, and VEGF in the serum. These findings support the concept of an angiogenic and inflammatory element in the development of diabetic retinopathy.