Intravitreal l-Arginine injection reverses the retinal arteriolar vasoconstriction that occurs after experimental acute branch retinal vein occlusion.

To investigate the effect of l-Arginine on the retinal arteriolar diameter following acute branch retinal vein occlusion (BRVO) in minipigs. Under general anesthesia, 10 eyes of 10 minipigs were evaluated. Two hours after BRVO, an intravitreal juxta-arteriolar micro-injection of 30 microl l-Arginine 1 mM (pH = 7.4) was performed in 7 eyes. Three eyes received a micro-injection of 30 microl of the solvent (pH = 7.4) that was used to prepare the solution of l-Arginine and served as controls. Retinal arteriolar diameter changes were measured using a Retinal Vessel Analyzer. Overall (n = 10), 2 h after BRVO there was a 10.5 +/- 1.9% decrease in the retinal arteriolar diameter in the affected territories compared to baseline (p < 0.001). An increase of 16.0 +/- 3.0% (p = 0.001) and 21.0 +/- 7.0% (p = 0.013) of the arteriolar diameter was evidenced 10 and 15 min respectively after l-Arginine injection (n = 7) compared to the diameter prior to l-Arginine injection. Thereafter, the vasodilatory effect of l-Arginine started to decrease but persisted and remained significant at the end of the study period (5.0 +/- 1.5% at 30 min, p = 0.007). Micro-injection of the solvent alone (n = 3) did not produce any significant effect on the retinal arterioles, which remained constricted at all time-points (p > 0.1). These findings demonstrate a significant arteriolar vasodilation after intravitreal juxta-arteriolar l-Arginine micro-injection in eyes with experimental BRVO in the affected territories. l-Arginine micro-injection can reverse the arteriolar vasoconstriction that occurs in acute experimental BRVO by stimulating nitric oxide production.

Development and optimisation of a portable micro-XRF method for in situ multi-element analysis of ancient ceramics.

Non-destructive analysis of cultural objects by micro-XRF spectrometry is an advantageous multi-element technique that has rapidly developed during the past few years. Portable instruments contribute significantly to the in situ analysis of valuable cultural objects, which cannot be transported to the laboratory. Ancient ceramics are the most common archaeological findings and they carry a significant historical content. Their analysis often presents certain particularities due to surface irregularities and heterogeneity problems. In the present work, the analytical characteristics (beam spot size, geometry effect and detection limits) of a compact and portable micro-XRF instrument with a monocapillary lens are presented in details. The standard reference materials SARM 69, SRM 620, NCS DC 73332 and the reference materials AWI-1 and PRI-1 were analysed for the determination of the detection limits (DL's) and the evaluation of the accuracy of the micro-XRF. Emphasis is given on the critical parameters, which should be monitored during measurements and influence the final results in the analysis of ancient ceramics. A quantitative analysis of ancient ceramic samples from Abdera (North Greece) is also presented.