Effects of topical pre-treatment with dexamethasone on the immediate and late phases of topically induced ocular anaphylaxis in the rat

We tested the effects of pre-treatment with dexamethasone on topically induced ocular anaphylaxis in the rat. Rats were immunized with dinitrophenylated Ascaris suum extract and challenged with di-DNP-lysine. Dexamethasone was administered topically once (24, 6, or 1 h before challenge) or three times (6, 4, and 2 h before challenge). A single pre-treatment given at 24 or 6 h had no significant effect. A single pre-treatment 1 h before challenge reduced the extent of edema assessed histologically but not clinically, and had no significant effect on the eosinophil count in conjunctival tissue examined 6 h after challenge. Eyes pre-treated with dexamethasone 6, 4, and 2 h before challenge showed a significant reduction in conjunctival edema assessed histologically and clinically 1 h after challenge. In addition, 6 h after challenge the number of eosinophils was significantly reduced. We conclude that repeated pre-treatment with dexamethasone can suppress both the immediate phase and the cellular late phase of topically induced ocular anaphylaxis.     

Pigmented paravenous chorioretinal atrophy

Two patients with pigmented paravenous chorioretinal atrophy are presented. Both patients had chorioretinal atrophy with pigment clusters located in the paravenous areas, and one of the patients had macular affection. This patient had exotropia and juvenile cataract, the other patient had senile cataract. Electroretinography showed decreased, but not totally extinguished potentials. Automatic and manual perimetry revealed relative and absolute scotomas corresponding to the atrophic paravenous areas. To our knowledge this is only the sixth report of pigmented paravenous chorioretinal atrophy with macular affection.     

Antioxidant enzyme activities and total nitrite/nitrate levels in the collar model. Effect of nicardipine.

There is a large body of literature describing the causative role of oxidative stress mediated by increased levels of reactive oxygen species in the pathogenesis of cardiovascular disease such as atherosclerosis, hypertension, and restenosis after angioplasty. The positioning of a soft silicone collar around the rabbit carotid artery elicits intimal thickening. The findings from recent studies demonstrated that both intimal thickening and atherosclerosis lead to synthesis of inducible nitric oxide synthase, resulting in abundant amounts of nitric oxide. We investigated the effects of collaring and nicardipine treatment on the activities of antioxidant enzymes, superoxide dismutase and catalase, and total nitrite/nitrate levels, stable products of nitric oxide. Placing the collar increased the total nitrite/ nitrate levels and decreased superoxide dismutase activity in collared arteries. Treatment with nicardipine (20 mg/kg/day, s.c.) prevented enhanced nitric oxide degradation without affecting superoxide dismutase and catalase activities. Our results suggest that enhanced nitric oxide production and superoxide anion are generated in response to the collaring, resulting in oxidative stress within the segment in this model.     

Tensile strength of plate osteosynthesis. Comparative biomechanical study of the original autocompression plate and a functional modification using the ZESPOL principle

In order to overcome the problems of stress protection and pressure atrophy of bone, which are associated with the traditional plating technique, in Poland a modified type of plating, ZESPOL has been, developed. In this procedure, the plate is not screwed onto the surface of the bone, but is fixed above the bone by special platform screw bolts in a comblike construction. This paper describes an experimental biomechanical investigation, using cadaver tibia, which compares the stability of the ZESPOL principle with that of the traditionally applied autocompression plate (ACP). In order to make the system biomechanically comparable, instead of the original ZESPOL plates, which are different in dimension, an ACP was used that was specially adapted to fit the ZESPOL criteria. Compared to the ACP, the bending stability of the ZESPOL osteosynthesis was found to be significantly less. When the same stress was applied, the total bending capacity of the ZESPOL system was found to be between 9% and 1348% higher, depending on the position of the plate and the direction of the force applied. In addition, the gap of the osteotomy site was between 6% and 923% greater with the ZESPOL system. Deformation of the bone adjacent to the osteotomy site was more closely approximate to intact bone with ACP than with ZESPOL plate. Our evaluations show that the ZESPOL system has less bending stability than ACP, without having the advantage of a more physiological bone-bending curve. However, the stability of the new system can be regarded as being overall sufficient.