Use of embryonic chick lens for screening potentially toxic chemicals

The Use of the Cultured Bovine Lens to Measure the In Vitro Ocular Irritancy of Ketones and Acetates

A novel in vitro alternative to in vivo eye toxicity testing measures the optical response (focal variability) of the cultured bovine lens (obtained from abattoirs) in response to exposure to potentially toxic chemicals. This approach involves measuring the optical quality of the lens by using a scanning laser system consisting of a low power scanning laser, a video camera and a video frame digitiser. This test was used to provide a rank order for the toxicity of four acetates (cellosolve acetate, ethyl acetate, methyl acetate and n-butyl acetate) and four ketones (methyl ethyl ketone, methyl isobutyl ketone, acetone and methyl amyl ketone) based on the time taken to produce a 100% increase in lens focal variability. The results indicate that the cultured lens is very sensitive to chemical damage. In particular, the test provides a much wider range of end values than does the in vivo test, especially at low concentrations.

The Charles F. Prentice award lecture 2009: Crystalline lens research and serendipity in science

Whether it is called serendipity or creativity, the process of scientific discovery is not one that lends itself to advance planning or programming, nor does it lend itself to an emphasis solely on applied research, research with industrial partners, or large teams of researchers because researchers must rely on intuition and the capacity to move quickly in new directions. Studies in my laboratory began with efforts to relate lens embryonic development to lens optical performance in a variety of vertebrate species. The initial direction concerned the optics of the fish eye, a system in which a spherical lens is essentially the only refractive component of the eye and one in which accommodation takes place by means of lens movement. This in turn led to an interest in how amphibious animals cope with the refractive transition that takes place when moving from air to water and vice versa. The development of a super accommodative ability in some diving birds is one adaptation that was explored. These curiosity-driven efforts led in turn to the development of a scanning laser system that provided a tool that can be used to evaluate the process of cataract development, either on the basis of in vivo exposure to chemicals or electromagnetic radiation and subsequent analysis of the excised lens or to the in vitro study of the lens in long-term whole lens culture experiments. The same approach has also been used as an in vitro ocular toxicology assay to develop sensitive in vitro methods to reduce regulatory dependence on the use of live animals. Finally, these applied directions in turn created new basic knowledge concerning the morphology and physiology of eye tissue organelles, particularly the morphology, distribution, and dynamic properties of the mitochondria found in the lens and in the retinal pigment epithelium.

Dose-response of the cultured bovine lens to butyl, methyl and propyl parabens

Pre-screening of cosmetic ingredients is vital for consumer safety. Previous in vivo techniques, such as the Draize test, have proved to be unreliable in predicting ocular irritancy and therefore there is a need for alternate testing methodologies. One such test is the scanning laser in vitro assay system which quantifies irritancy based on the focusing ability of the cultured bovine lens. In combination with confocal microscopy, a more thorough documentation of ocular irritancy can be achieved. This study investigates the response of cultured bovine lenses over time to butyl, methyl and propyl parabens, which are common antimicrobial agents found in cosmetic and ophthalmic products. The focusing ability of the lens was measured with an automated laser scanner over a period of 96 h. At 120 h post-treatment, the lenses were analysed by using a confocal laser scanning microscope to determine the characteristics of nuclei, and the morphology and distribution of mitochondria within the lenses. Irritancy to the three parabens was investigated at both an optical and cellular level. Each of the parabens was tested at 0.002% and 0.2%, where the 0.2% butyl paraben was found to be the most irritating.

The effects of toxicological agents on the optics and mitochondria of the lens and the mitochondria of the corneal epithelium

This review describes how the morphology and distribution of the mitochondria of the epithelium and the superficial fibre layers of the lens were studied using confocal scanning laser microscopy. This research was correlated with an effort to use the optical properties of the intact lens in culture as a proxy for the cornea in measuring ocular toxicity. In turn, this work led to the confocal study of the in vitro and then the in vivo cornea and their possible use in using confocal microscopy to evaluate the effect of various treatments on the integrity of the surface of the eye. Finally, confocal examination of the mitochondria of the lens has provided an avenue to the study of mitochondrial dynamics.

Optical response of the cultured bovine lens; testing opaque or partially transparent semi-solid/solid common consumer hygiene products

This study determines the relative ocular lens irritancy of 16 common partially transparent or non-transparent consumer hygiene products. The irritancy was found by measuring the changes in the sharpness of focus [referred to as the back vertex distance (BVD) variability] of the cultured bovine lens using a scanning laser In Vitro Assay System. This method consists of a laser beam that scans across the lens, and a computer, which then analyses the average focal length (mm), the BVD variability (mm), and the intensity of the beam transmitted. Lenses were exposed to the 16 hygiene products and the lens' focusing ability was monitored over 192 h. The products are semi-solids or solids (e.g. gels, lotions, shampoos). They are categorized into six groups: shampoos, body washes, lotions, toothpastes, deodorant, and anti-perspirant. Damage (measured by > 1 mm BVD variability) occurred slower for the shampoos, especially in the case of baby shampoo. The results indicate that shampoos exhibit the lowest level of ocular lens toxicity (irritability) while the deodorant is the most damaging.

Quantitative cell culture biocompatibility testing of medical devices and correlation to animal tests

The biocompatibility of a wide variety of biomaterials was quantitatively assessed, in a physiologically normal environment" as to cytotoxicity induced in WI-38 cells by cell culture medium extracts. Materials tested included PVC plastic, rubber, silicone rubber, polyethylene, polypropylene, acetal, polyurethane, Teflon, nylon, epoxy, and polystyrene. Cell culture test results were correlated to U.S.P. animal tests. Potential test artifacts, lead, barium, cadmium, and endotoxin were tested for cytotoxicity in WI-38 cells. Cell culture methods yielded more positive tests, particularly rubber, PVC plastic and silicone rubber compounds, than observed in U.S.P. animal tests. Positivity in animal tests did not correlate quantitatively to cytotoxic titers in cell culture. Discrepancies between cell cultures tests and animal tests, specifically rubber compounds, were attributable, in some instances, to differentials in elution efficiency between saline, cottonseed oil, and complete MEM cell culture medium. In other instances, particularly PVC plastics, differences between cell culture and animal test results were due to an inherent difference in the two indicator systems to respond to specific toxic moieties.