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A biplanar cephalometric stereoradiography (BCSR) technique was developed for accurate three-dimensional assessment of structures that can be identified by markers or anatomical landmarks that are visible on both lateral closed and posteroanterior cephalometric radiographs. The accuracy and precision of the technique were determined by means of a phantom and clinical radiographs. On the phantom, three-dimensional coordinates were determined by the BCSR technique and were measured directly with an electronic digital caliper. The accuracy of the BCSR technique was found to be within 0.5% of the measured distances. On clinical radiographs, the lengths of plates and screws, used as rigid fixation devices, were measured on two subsequent sets of biplanar radiographs and were found to be within the accuracy of our current digitizer (+/- 0.381 mm). The stability of interosseous wires was tested against implants and other interosseous wires on two subsequent sets of biplanar radiographs through a comparison of the distances between two devices. These comparisons confirmed the stability of interosseous wires. The BCSR technique proved to be an accurate method for measurements in three dimensions.

A model of topically induced ocular anaphylaxis was developed. Male Sprague-Dawley rats were immunized by intraperitoneal injections of egg albumin (EA) and alum and topically challenged with EA. Application of EA induced clinical (conjunctival edema) and histologic (mast cell degranulation) signs of anaphylaxis, when the antigen was preceded by topical application of dithiothreitol (DTT), a mucolytic agent. Rats challenged by four EA applications did not differ significantly in clinical edema or mast cell degranulation from those challenged by one EA application at the same (0.1 M DTT) pretreatment level, but there was significantly greater histologically assessed edema in the eyes challenged four times.

A hapten (DNP) model of topically induced ocular anaphylaxis has been developed. Rats immunized with DNP-Ascaris were skin-tested with DNP-bovine serum albumin (DNP-BSA) and Evans blue and challenged topically with varying amounts of di-DNP-lysine. The degree of clinical conjunctival edema was assessed, and eye tissues were evaluated histologically. Clinical conjunctival edema and histologic mast cell degranulation increased with higher concentration of di-DNP-lysine. In general, rats with positive skin tests showed more clinical conjunctival edema and more mast cell degranulation than those with negative skin tests. Three other groups of rats with positive skin tests to the DNP-BSA were injected intravenously with 125I-BSA and challenged topically with di-DNP-lysine. Retention of 125I-BSA in ocular adnexa and in globes was higher in di-DNP-lysine- than in PBS-challenged eyes. The hapten model simulates the ocular component of human hay fever in that ocular anaphylaxis is induced in immunized rats by topical challenge with antigen alone.