Quantitative in vitro assessment of phototoxicity using a human skin model, Skin2

The ability to accurately predict the phototoxic potential of personal and skin care products remains a key element in assessing the safety of premarketed products. To find a reliable in vitro alternative test for photoirritancy, the European Commission and the European Cosmetic Association are conducting a 3-year, European validation study. Based on the results of this study, an in vitro photoirritancy method will be selected for incorporation into new international guidelines for photoirritancy testing. As a part of this study, Skin2, a cultured human skin system, was used to evaluate the phototoxic potential of chemicals with known photoirritative properties. The Skin2 ZK1351, a 3-dimensional co-culture system, consists of dermal fibroblasts and a multilayered epidermis comprising differentiated keratinocytes. This product line has previously been used to evaluate the irritative potential of topically applied ingredients and products. In this study, various concentrations of the test chemicals were applied to the epidermal side of the Skin2 tissue for contact times of 1 h or 24 h and then the tissue was exposed to 2.9 J/cm2 of ultraviolet A (UVA) radiation. Treated but nonirradiated tissues were also assayed to predict the cytotoxic potential of the test chemicals, which could mask the phototoxic reaction. After exposure, the tissue substrates were rinsed free of test chemicals and allowed to recover for 24 h. Following this incubation, the MTT reduction assay was used to assess cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

ZEBET's Data Bank and Information Service on Alternatives to the Use of Experimental Animals in Germany

There is limited availability of reliable and valid information on alternative methods to the use of experimental animals from open access data banks. In 1989, the Centre for Documentation and Evaluation of Alternative Methods to Animal Experiments (ZEBET) at the German Federal Health Office started a data bank to meet requirements of the German Animal Protection Act. In comparison with other data banks in this field, ZEBET's data bank comprises two types of evaluation: firstly, whether a specific method contributes to the Three Rs concept of Russell & Burch, i.e. replacement, reduction and refinement, and secondly, whether the method meets the criteria of validation as outlined in the report of the Amden workshop on validation of toxicity test procedures. This information is primarily available to the scientific and ethical commissions which have been introduced by the Animal Protection Act in order to reduce the numbers of animals used in experiments in Germany. However, other users of the ZEBET data bank are also welcome, e.g. local animal protection officers, interested scientists and the public. Although the language of ZEBET's data bank is German, the documentation also contains English summaries, key words, and updated lists of references. Here, the concept of ZEBET's data bank and its scientific background are described and compared with other alternatives data banks.

Comparative glucose tolerance studies in the freshwater snail Biomphalaria glabrata: influence of starvation and infection with the trematode Schistosoma mansoni

The dynamic reactions of B. glabrata on intravasal loads of 20-1000 micrograms glucose.g live fresh wt-1 were studied in standard fed snails (SFS). Starved snails (SS) and snails infected with S. mansoni (IS) were given 100-500 micrograms glucose.g fresh live wt-1. Mean hemolymph glucose level was 12.1 mg.100 ml-1 in SFS. It was not significantly lower in SS (10.7 mg.100 ml-1), but significantly reduced in IS (8.5 mg.100 ml-1). Since hemolymph volumes were significantly increased in SS, the amount of circulating glucose (pool) did not change (75 micrograms.g body weight-1) compared to SFS (62 micrograms.g-1). It was, however, reduced to 41 micrograms.g-1 in IS. In SFS the circulating glucose pool had to be doubled to induce significantly elimination of the injected glucose. Tripled pools were eliminated with half-times of 45 min, whereas lower and higher glucose loads were eliminated significantly slower (half-times: 80-105 min). Glucose tolerance of SS was reduced: half-times were doubled, and metabolization of injected glucose was reduced. Since tissue fresh weights were lowered by 40%, absolute incorporation of 14C from labeled glucose was lowered, but specific incorporation (per mg) was higher than in SFS and IS. Glucose tolerance of IS was increased: metabolic clearance rates rose by 70% and half-times were shortened by 30%, though absolute and specific rates of 14C incorporation were lowered. However, IS lost 25% of the label to the water, whereas SFS lost 12% and SS only lost 8%. Using the antimetabolite 2-deoxyglucose, 80% of the losses proved to be glucose in IS, and 50% in SFS. The present results suggest the existence of a glucostatic regulation in B. glabrata with lower sensitivity and capacity than in mammals. As to glucose tolerance, the often reported parallelism in metabolic shifts induced by starvation and parasitic infection was not confirmed.