High-Resolution Digital Integral Photography by use of a Scanning Microlens Array.

We suggest what we believe is a new three-dimensional (3-D) camera system for integral photography. Our method enables high-resolution 3-D imaging. In contrast to conventional integral photography, a moving microlens array (MLA) and a low-resolution camera are used. The intensity distribution in the MLA image plane is sampled sequentially by use of a pinhole array. The inversion problem from pseudoscopic to orthoscopic images is dealt with by electronic means. The new method is suitable for real-time 3-D imaging. We verified the new method experimentally. Integral photographs with a resolution of 3760 pixels x 2560 pixels (188 x 128 element images) are presented.

Degradable poly(anhydride ester) implants: effects of localized salicylic acid release on bone.

Degradable poly(anhydride ester) implants in which the polymer backbone breaks down into salicylic acid (SA) were investigated. In this preliminary work, local release of SA from the poly(anhydride esters), thus classified as 'active polymers', on healthy bone and tissue was evaluated in vivo using a mouse model. Degradable polyanhydrides that break down into inactive by-products were used as control membranes because of their chemical similarity to the active polymers. Small polymer squares were inserted over the exposed palatal bone adjacent to the maxillary first molars. Active polymer membranes were placed on one side of the mouth, control polymers placed on the contra lateral side. Intraoral clinical examination showed that active polymer sites were less swollen and inflamed than control polymer sites. Histopathological examination at day 1 showed essentially no difference between control and active polymers. After 4 days, active polymer sites showed epithelial proliferation to a greater extent than the polyanhydride controls. After 20 days, active polymer sites showed greater thickness of new palatal bone and no resorptive areas, while control polymer sites showed less bone thickness as well as resorption including lacunae involving cementum and dentine. From these preliminary studies, we conclude that active polymers, namely poly(anhydride esters), stimulated new bone formation.

Synthesis and degradation characteristics of salicylic acid-derived poly(anhydride-esters).

A biodegradable poly(anhydride-ester) was synthesized by melt condensation polymerization of the acetylated monomer to yield a novel polymeric prodrug. The polymer we have synthesized is composed of alkyl chains linked by ester bonds to aromatic moieties, specifically salicylic acid--the active component of aspirin. With the medicinal properties attributed to salicylic acid and the ease of metabolism, the incorporation of this compound into a polymer backbone yields a polymeric prodrug that may have potential in a variety of applications (i.e., inflammatory bowel disease). For these reasons, we have designed a synthetic scheme that yields the desired poly(anhydride-ester). The in vitro hydrolytic degradation of these polymers has been performed and results indicate that the polymer degradation rate is pH-dependent.

Testing of refractive silicon microlenses by use of a lateral shearing interferometer in transmission.

Wave aberrations of refractive photoresist microlenses and silicon microlenses were measured with a lateral shearing interferometer. Because of the silicon elements, a near-infrared working wavelength (lambda = 1.32 mum) was used. The wave front was evaluated by a phase step technique with four steps. Integration of the phase distributions was performed with a computationally efficient Fourier transformation algorithm. The influence of the detector vidicon nonlinearity on the measured wave front was calculated. The defocusing behavior of the interferometer was investigated by fitting the measured wave fronts with the help of Zernike circle polynomials. It is shown that the reproducibility can be kept below lambda/100 rms. Examples for the measured wave fronts of plano-convex silicon microlenses are discussed in detail.

Allithiamine ingestion does not enhance isokinetic parameters of muscle performance.

The purpose of this study was to investigate the effect of oral allithiamine administration on isokinetic parameters of muscle performance and lactate accumulation prior to, during and in recovery from isokinetic exercise. A double-blind, counterbalanced, crossover experimental design utilizing a Biodex System 2 Isokinetic Dynamometer was used to test 15 healthy college students. Subjects orally ingested either 1 g. day-1 of a thiamin derivative, allithiamine, or placebo for 5 days and then performed six exercise sets of knee extension and flexion. ANOVA revealed no significant differences between treatment conditions in peak torque, mean peak torque, average power, or total work performed (p > .05). Likewise, lactate accumulation was not significantly different between treatment conditions at any measurement point (p > .05). The absence of significant differences suggests that oral allithiamine administration does not enhance isokinetic parameters of muscle performance or lactate accumulation prior to, during, and following isokinetic exercise.

Topography of corneal grafts before and after penetrating keratoplasty.

PURPOSE: Refractive error after penetrating keratoplasty is a major clinical problem. The purpose of the present study was to investigate whether the topography of the donor cornea influence the topography of the graft after transplantation. METHODS: Twenty-five donor corneas were measured with a video-keratograph (TMS-1): in situ and before and after organ culture. Clinical video-keratographic images of the transplanted grafts were subsequently obtained one week, 1, 3, 6, 12, and 24 months after surgery. The central spherical equivalent power and corresponding regular and irregular astigmatic powers were computed. RESULTS: A statistically significant correlation between spherical equivalent central donor power and spherical equivalent central graft power after keratoplasty was found at all times up to two years after surgery. Only 13-50% of the variation in post-keratoplasty spherical graft power could, however, be explained by the donor graft power. Corresponding 95% confidence limits for prediction of post-keratoplasty power from donor graft power were approximately +/- 6.5 diopters. Post-keratoplasty regular or irregular corneal astigmatism did not correlate with astigmatism in the donor graft. CONCLUSION: Corneal donor graft spherical equivalent power does influence the spherical equivalent corneal power after keratoplasty, especially during the first months after surgery. The dependency is, however, not very strong and until other determinants of post-keratoplasty corneal shape are known and controllable, 'power-typing' of donor corneas appears to be of limited clinical use.

Residual urine in 75-year-old men and women. A normative population study.

The prevalence of residual urine in elderly people in the community is poorly documented. The aim of the present study was to assess the prevalence and range of residual urine in elderly people in the community. As part of a major epidemiologic study (The Glostrup Population Study), 140 75-year-old men and women were included in this study (92 men, 48 women). All were selected at random from the Central Person Register by age and residence. All had a single sonographic measurement of residual urine with a prevoid volume of 150 ml or more. More than 10 ml of residual urine was found in 91 of the 92 men (median 90 ml; range 10-1502 ml), and in 44 of the 48 women (median 45 ml; range 0-180 ml). Our figures correspond to those previously reported in selected patient populations. It must be emphasized, however, that our findings are merely descriptive, as the clinical significance of a single residual urine determination is questionable.

Fourier analysis of video-keratographic data. A tool for separation of spherical, regular astigmatic and irregular astigmatic corneal power components.

Topographic analysis of the cornea and computation of changes in corneal topography is difficult because of the lack of a standardized concept for analysing topographic information. We have used Fourier series harmonic analysis to decompose the often very complex information given in topographic images (TMS-1 video-keratograph). The polar data values arising from each mire were separated into spherical (average power), regular astigmatic (2' harmonic) and non-regular astigmatic components. The non-regular astigmatic components were further divided into a decentration component (1' harmonic) and a higher order irregular refractive component (root mean square (r.m.s.) of the residual between original data and the sum of spherical, 1' and 2' order components). Algorithms for utilizing the Fourier analysis technique on subjective refractive and on keratometric changes in regular astigmatism were also derived. Averages of the separate refractive components were calculated for groups of normal (right and left eye of 25 patients), keratoconic (13 eyes), and transplanted eyes (20 eyes), and average topographic maps were reconstructed and imaged. Changes in the separate topographic refractive components were compared with subjective refractive changes in eyes that had undergone combined myopic-astigmatic excimer laser ablation (8 eyes). Fourier series analysis was found superior to conventional keratometry in predicting spherical and regular astigmatic changes in subjective refraction. Fourier series analysis seems to be a powerful tool to decompose the information of complex topographic corneal images into rational optical components.

Long-term results with organ cultured, cryopreserved human corneal grafts. Re-examination of 17 patients.

Seventeen organ cultured cryopreserved corneas were grafted in 1978-79. When published in 1982, 12 of the grafts (71%) were clear with an average thickness of 0.51 mm and an endothelial density of 1028 cells/mm2. A re-examination of these patients after 13 years is presented. Seven grafts (58%) were clear. Average CCT was 0.51 mm and endothelial cell density was 988 cells/mm2. Visual acuity was 0.4 or better. The morphology resembled that seen after 1 year with large, multinucleated cells. It is concluded that cryopreserved grafts show a fair long-term survival. Cryopreservation may still present a possibility in the establishment of a corneal bank with the perspective of supplying histocompatible donor material.