Zebrafish embryos as an alternative to animal experiments--a commentary on the definition of the onset of protected life stages in animal welfare regulations.

Worldwide, the zebrafish has become a popular model for biomedical research and (eco)toxicology. Particularly the use of embryos is receiving increasing attention, since they are considered as replacement method for animal experiments. Zebrafish embryos allow the analysis of multiple endpoints ranging from acute and developmental toxicity determination to complex functional genetic and physiological analysis. Particularly the more complex endpoints require the use of post-hatched eleutheroembryo stages. According to the new EU Directive 2010/63/EU on the protection of animals used for scientific purposes, the earliest life-stages of animals are not defined as protected and, therefore, do not fall into the regulatory frameworks dealing with animal experimentation. Independent feeding is considered as the stage from which free-living larvae are subject to regulations for animal experimentation. However, despite this seemingly clear definition, large variations exist in the interpretation of this criterion by national and regional authorities. Since some assays require the use of post-hatched stages up to 120 h post fertilization, the literature and available data are reviewed in order to evaluate if this stage could still be considered as non-protected according to the regulatory criterion of independent feeding. Based on our analysis and by including criteria such as yolk consumption, feeding and swimming behavior, we conclude that zebrafish larvae can indeed be regarded as independently feeding from 120 h after fertilization. Experiments with zebrafish should thus be subject to regulations for animal experiments from 120 h after fertilization onwards.

Principles and perspectives.

BACKGROUND, AIM AND SCOPE: With respect to the enormous increase of chemical production in the last decades and the tens of thousands of individual chemicals on the market, the permanent improvement of chemical management is a permanent target to achieve the goals of sustainable consumption and production set by the WSSD in Johannesburg 2002. MAIN FEATURES: Several approaches exist to describe sustainability of chemistry. However, commonly agreed criteria are still missing. There is no doubt that products of modern chemistry help to achieve important goals of sustainability and that significant improvements have occurred regarding direct releases from production sites, but several facts demonstrate that chemistry is far from being sustainable. Still too many chemicals exhibit hazardous characteristics and pose a risk to health and environment. Too many resources are needed to produce chemicals and finished products. RESULTS AND CONCLUSION: Therefore, a strategy for sustainability of chemistry should be developed which comprises the following main elements: 1. Sustainable chemicals: sustainable chemical management includes a regulatory framework which makes no difference between new and existing chemicals, contains efficient information flow through the supply chain which allows users to handle chemicals safely and offers an authorisation procedure and/or an efficient restriction procedure for substances of high concern. This regulatory scheme should promote the development of inherently safe chemicals. 2. Sustainable chemical production: Sustainable chemical production needs the development and implementation of emerging alternative techniques like selective catalysis, biotechnology in order to release less CO2 and less toxic by-products, to save energy and to achieve higher yields. Information exchange on best available techniques (BAT) and best environmental practices (BEP) may help to promote changes towards more sustainability. 3. Sustainable products: An integrated product policy which provides a framework for sustainable products promotes the development of products with a long-term use phase, low resource demand in production and use, low emission of hazardous substances and properties suitable for reuse and recycling. This may be promoted by eco-labelling, chemical leasing concepts and extended information measures to enhance the demand of consumers and various actors in the supply chain for sustainable products. RECOMMENDATION AND PERSPECTIVE: Important tools for the promotion of sustainable chemistry are the abolition of barriers for innovation in legislation and within the chemical industry, more transparency for all users of chemical products, a new focus on sustainability in education and research, and a new way of thinking in terms of sustainability.

The angle between the Frankfort horizontal and the sella-nasion line. Changes in porion and orbitale position during growth.

AIM: The starting point of this study was the statement made in the literature that the angle between the two reference planes Frankfort horizontal (FH) and sella-nasion line (SN) changes relatively little during growth. The growth-induced relocation of the orbitale (Or; anterior reference point of the FH) in relation to SN is known from implant studies, whereas the relocation of the porion (Po; posterior reference point of the FH) has been the subject of only little research. The present study was aimed at analyzing the factors contributing to the almost constant angle between FH and SN. MATERIAL AND METHOD: The study material consisted of two groups of macerated skulls and the relevant lateral cephalograms. The first group comprised 32 skulls of individuals aged 2.5 to 5 years, and the second group ten skulls of individuals aged 18 to 20 years. A diagram showing the growth-dependent changes was prepared with reference to the mean values for the two groups. The cephalograms were superimposed on the anterior cranial base line at sella point (S). RESULTS: A 3.1 degrees increase in the angle between FH and SN during growth was recorded in our investigations. The distance between Or and SN increased by 3.9 mm while Po remained vertically almost constant with respect to SN. In sagittal direction the distance between Or and S also increased, while Po was displaced to almost the same extent in the opposite direction. The increasing vertical distance between the anterior and posterior reference points of FH and SN was largely compensated by the sagittal developments of the reference points Po and Or, so that the angle between these two planes changed very little. The relatively stable angle between FH and SN thus showed by no means a constant relationship of the four reference points to one another.