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T h e e t h i c s o f r e s e a r c h i n v o l v i n g a n i m a l s neurological dysfunction, behavioural and gait abnormalities as well as weight loss. Researchers aimed to limit suffering by euthanising <strong>animals</strong> when they were unable to eat or drink without assistance or when they reached certain stages that were known to precede the experimentally induced terminal disease. 10.13 <strong>The</strong> scientific <strong>research</strong> that was carried out on BSE strongly influenced public health policy and led to the introduction <strong>of</strong> control methods in cattle and sheep. Animal tests showed that pigs and chickens were not susceptible to BSE when fed with infected tissue, which meant that the same control measures were not necessary for these species. Other <strong>research</strong> helped to identify further measures to protect humans from infective TSE agents. <strong>The</strong>se included the removal <strong>of</strong> brain and spinal cord material from meat destined for public consumption and the implementation <strong>of</strong> the Over Thirty Month Scheme (paragraph 6.22). BSE pathogenesis studies in sheep also showed that blood can be a source <strong>of</strong> infection. In response to the hypothesis that two people who died <strong>of</strong> vCJD had been infected by a blood transfusion, the Department <strong>of</strong> Health announced in 2004 that anyone who had received a blood transfusion in the UK since 1980 would no longer be able to donate blood (paragraph 6.24). 10.14 Animal disease models were also used for <strong>research</strong> on hepatitis C, and polio. <strong>The</strong> hepatitis C virus worldwide affects 170 million people, many <strong>of</strong> whom develop cirrhosis and liver cancer. Polio is estimated to be responsible for causing disability in more than half a million people around the world per year in the late 1950s and early 1960s. <strong>The</strong>re are hopes that the virus will soon be eliminated. <strong>The</strong> hepatitis C virus was found to infect only primates and early <strong>research</strong> involved chimpanzees and monkeys. With regard to welfare implications, if the <strong>animals</strong> develop hepatitis C, they are likely to experience similar physiological symptoms to humans. <strong>The</strong>se may range from malaise to paralysis. <strong>The</strong> symptoms associated with polio affect a whole range <strong>of</strong> behaviours including ambulation, climbing, social interactions, grooming and foraging. Affected <strong>animals</strong> are likely to be aware <strong>of</strong> their deficiencies and so may experience distress at not being able to carry out normal behaviours. In long-term <strong>research</strong> <strong>animals</strong> have to be isolated as they will be infectious to other <strong>animals</strong> and humans, and their welfare may be negatively affected. 10.15 We described two areas <strong>of</strong> <strong>research</strong> where progress continues to be difficult. Despite the use <strong>of</strong> animal <strong>research</strong> to improve understanding about the biological processes underlying diseases such as HIV/AIDS and various forms <strong>of</strong> cancers, fully effective cures or vaccines have not yet been developed. Due to the complex pathogenesis <strong>of</strong> these diseases which have many different sub-types in humans and <strong>animals</strong> there are inherent difficulties in studying them and developing successful animal models. However, effective treatment has been developed for some types <strong>of</strong> cancer, such as breast or prostate cancer. Scientists involved in this type <strong>of</strong> <strong>research</strong> believe that refined models (especially primate models) may accelerate scientific progress. Transgenic mice have also been developed which express human receptors on their cells and may be used as replacements for primates in certain experiments (paragraph 6.35). GM disease models (Chapter 7) 10.16 GM <strong>animals</strong> are increasingly being used in the study <strong>of</strong> human disease. Scientific advances allow the creation <strong>of</strong> animal models <strong>of</strong> diseases with a genetic component in a targeted way, reflecting the genetic patterns that underlie the human version <strong>of</strong> the disease. Examples include models for diabetes, deafness, psychiatric disorders, neurodegenerative disorders and cancers. 10.17 Some <strong>animals</strong> are used for the study <strong>of</strong> genetic diseases because <strong>of</strong> the strong genetic similarities between humans and many other species. For example, 99 percent <strong>of</strong> genes in 174
T h e e t h i c s o f r e s e a r c h i n v o l v i n g a n i m a l s mice have direct counterparts in humans (paragraph 7.2). Most biomedical scientists maintain that the similarities between mice and humans are sufficient to make informative comparisons. Furthermore, the differences may be as instructive as the similarities when investigating the mechanistic basis <strong>of</strong> disease (paragraph 7.10). Scientists using <strong>animals</strong> in this field therefore maintain that careful analysis <strong>of</strong> mouse models can provide significant information on the function <strong>of</strong> genes in mammalian disease processes (paragraph 7.10). Other species with suitable genomes for comparative studies such as the zebrafish and the rat are being increasingly used (paragraphs 7.11-7.13). 10.18 Information from mouse models has enabled scientists to investigate the relationship between mutations and the nature and severity <strong>of</strong> the disease they cause. <strong>The</strong> glucokinase gene in diabetes is one such example. <strong>The</strong> use <strong>of</strong> the mouse model shaker1 has also led to the discovery <strong>of</strong> a gene causing pr<strong>of</strong>ound hearing loss in both mice and humans (see paragraph 7.9). Mouse models are also important for investigating how one disease can produce varying symptoms in different individuals. Indirect changes, for example in levels <strong>of</strong> a protein or a hormone, may prove to be more suitable therapeutic targets than the genes themselves, as in the case <strong>of</strong> patients with neurodegenerative disorders (see paragraph 7.9). <strong>The</strong> use <strong>of</strong> GM <strong>animals</strong> can entail a wide range <strong>of</strong> welfare implications, as the <strong>animals</strong> involved usually suffer from the disease being studied for the duration <strong>of</strong> their lives (paragraph 4.57). <strong>The</strong>y are also likely to be the subject <strong>of</strong> procedures carried out to characterise the different stages <strong>of</strong> the disease, including blood, metabolic and behavioural tests. <strong>The</strong> very low success rates in producing a strain <strong>of</strong> animal that can serve as a disease model also require attention (see Box 5.6). CHAPTER 10 SUMMARY OF SECTION 2 Animal use by the pharmaceutical industry (Chapter 8) 10.19 Use <strong>of</strong> <strong>animals</strong> within the pharmaceutical industry is a crucial part <strong>of</strong> the <strong>research</strong> and development process for new medicines. <strong>The</strong> number <strong>of</strong> <strong>animals</strong> used by the pharmaceutical industry has fallen over the last two decades due to the application <strong>of</strong> new technologies, new materials and increased use <strong>of</strong> computational analysis (see paragraph 8.4). In the UK in 2003, 36 percent <strong>of</strong> the total number <strong>of</strong> procedures performed on <strong>animals</strong> were undertaken by the commercial sector. 10.20 Relatively small numbers <strong>of</strong> <strong>animals</strong> are used in the early stages <strong>of</strong> drug discovery, particularly in the identification <strong>of</strong> targets for possible medicines. Many <strong>of</strong> the <strong>animals</strong> used at this stage are GM mice. <strong>The</strong>y are used to ascertain whether, for example, specific receptors might respond to chemical compounds which can be developed into new medicines. Animal models that reproduce relevant aspects <strong>of</strong> human genetic conditions, such as sickle cell anaemia, can be used to test how people affected by the disorder may react to different chemical compounds (see paragraph 8.16). 10.21 Sixty to eighty percent <strong>of</strong> <strong>animals</strong> used by the pharmaceutical industry are involved in the process <strong>of</strong> characterising promising candidate medicines (Table 8.1). Rodents are most commonly used, but larger <strong>animals</strong>, including rabbits, dogs and primates, are also used (see paragraph 10.24). Before a potential medicine is tested in human trials, the regulatory authorities must ensure that it has an acceptable balance <strong>of</strong> safety and efficacy, usually requiring data obtained from animal tests. Twenty five percent <strong>of</strong> the total number <strong>of</strong> procedures using <strong>animals</strong> in 2002 in the UK were conducted for the purpose <strong>of</strong> ‘applied human medicine’. Once a medicine is in clinical trials, animal tests continue to be carried out (paragraphs 8.27 and 8.29). 10.22 For certain biological compounds such as vaccines, animal testing is required for each batch that is produced, to ensure potency and safety (see paragraphs 8.35-8.36). Depending on the type <strong>of</strong> test there can be serious welfare implications. For example, if death is the 175
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The ethics
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The ethics
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Foreword The issue
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Table of contents
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Stages 1-2: discovery and selection
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Conclusions and recommendations ...
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Terms of reference
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T h e e t h i c s o f r e s e a r c
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Chapter 1 Introduction
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Chapter 2 The cont
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Chapter 3 Ethical issues raised by
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Chapter 4 The capa
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Section 2 Use of <
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Chapter 5 The use
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Chapter 6 The use
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Chapter 14 Discussion of</s
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Appendices
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Genetic screening: ethical issues P
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