Efficient evaluation of a three-dimensional eye-box in a near-eye display using light-field acquisition of luminance distribution.

We propose, what we believe to be, a novel assessment methodology for evaluating three-dimensional (3D) characteristics of an eye-box volume in a near-eye display (NED) using a light-field (LF) data acquired at a single measuring distance. In contrast to conventional evaluation methods for the eye-box, where a light measuring device (LMD) changes its position in lateral and longitudinal directions, the proposed method requires an LF of the luminance distribution (LFLD) for the NEDs captured only at the single observation distance, and the 3D eye-box volume is evaluated via a simple post-analysis. We explore an LFLD-based representation for the efficient evaluation of the 3D eye-box, and the theoretical analysis is validated by simulation results using Zemax OpticStudio. As experimental verifications, we acquired an LFLD for an augmented reality NED at a single observation distance. The assessed LFLD constructed a 3D eye-box successfully over the distance range of 20 mm, which included assessment conditions where it was hard to measure the light rays' distributions directly in the conventional methodologies. The proposed method is further verified by comparing with actual observed images of the NED both inside and outside of the evaluated 3D eye-box.

Human insulin microcrystals with lactose carriers for pulmonary delivery.

Dry powder formulations for pulmonary delivery are attractive because many issues of solubility and stability can be minimized. Human insulin microcrystals with lactose carriers were produced for pulmonary delivery. The average particle diameter was 2.3 microm, with a narrow, monodispersed size distribution. The percentages of high molecular weight proteins (%HMWPs), other insulin-related compounds (%OIRCs), and A-21 desamido insulin (%D(es)) were very low throughout the microcrystal preparation process. Administration of the microcrystal powder by intratracheal insufflation significantly reduced the blood glucose levels of Sprague-Dawley rats. The percent minimum reductions of the blood glucose concentration (%MRBG) produced by the insulin microcrystal powder and by an insulin solution reached 40.4% and 33.4% of the initial glucose levels respectively, and their bioavailability relative to subcutaneous injection (F) was 15% and 10% respectively. These results confirm that the insulin microcrystal powder prepared is suitable for pulmonary delivery in an effective dosage form.

Characterization of human insulin microcrystals and their absorption enhancement by protease inhibitors in rat lungs.

Pulmonary route appears to be an attractive alternative as a non-invasive systemic delivery for peptide and protein drugs. An appropriate formulation, however, is important for increasing their bioavailability in lung. In this study, the human insulin microcrystals were produced. The particle size analysis and scanning electron microscopy (SEM) showed that the microcrystals were uniform and had a monodispersed size distribution (mean diameter = 0.95 microm) for pulmonary delivery. The physicochemical properties of the microcrystals developed were similar to those of the commercial crystalline powder in powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses. The percentage of high molecular weight proteins (%HMWP), the percentage of other insulin related compounds (%OIRC) and the percentage of A-21 desamido insulin (%D) of the microcrystals were very low. In addition, the cytotoxicity of microcrystals developed and protease inhibitors (aprotinin, bacitracin and soybean-trypsin inhibitor) was investigated, and the enhancement of insulin absorption in the presence of these protease inhibitors at various concentrations was studied. The cell viability of A549 was over 80% at various concentrations of aprotinin and soybean-trypsin inhibitor, except for bacitracin (below 60%). The percent of decrease in blood glucose (D%) was 42.68+/-1.62% after intratracheal instillation of insulin microcrystals (5 U/kg). An enhancement of hypoglycemic effect with protease inhibitors was also found. Soybean-trypsin inhibitor (48.86+/-3.24% at 10 mg/ml; 55.78+/-0.71% at 5 mg/ml; 51.49+/-5.27% at 1 mg/ml) and aprotinin (52.57+/-8.78% at 10 mg/ml; 51.97+/-1.98% at 5 mg/ml; 56.90+/-3.42% at 1 mg/ml) were effective for absorption enhancement. These findings suggest that the use of insulin microcrystals and protease inhibitors would be useful to improve the hypoglycemic effect in pulmonary route.