Is Biomedical Research The Same Thing As Animal Modeling

Apply of brute models in biomedical enquiry

People ofttimes ask how the use of animals in experiments can be justified when animals are clearly so dissimilar from humans. The answer is that animals are used in specific areas of research where they practise not differ from humans for the characteritics being studied, and where the differences are of no significance to the project. Animals are therefore used as highly specific 'models' of humans.

Models should resemble the thing being modelled, but must exist different in other ways

The similarities and differences between models must be considered in every project. The important features of a model tin can exist seen using an analogy: a doll is a model of a human being used to entertain a child. To be a useful model for this purpose it needs to be similar a human in some respects, such every bit having characteristics that a child recognises as a head, a trunk, eyes, olfactory organ, limbs etc. Still, it is different from a human in many other respects. If information technology were to be more human, and have a nervous arrangement so that it feels pain, and blood so that information technology bleeds when damaged then it would be a worse model for its detail purpose. Nosotros would not want blood on the carpet or the upstanding dilema of causing pain.

A model must therefore be similar the thing being modelled in some respects, and different it in some other respects, with some characteristics existence neutral. Models are besides specific for a particular purpose. We cannot do medical reserch using dolls, and similarly a rat may exist suitable for some research projects and non for others.

Models can be "improve" than the affair being modelled

Humans have certain cognative abilities such as addition, subtraction, multiplication and division which can be modelled using an electronic reckoner. This sort of model can exist called a "super model" considering it performs a specific task better than the affair being modelled. Given the choice betwixt using our encephalon to multiply a two three digit numbers or the reckoner, about of us will cull the latter. The calculator is a highly abstract model of a very specific man function, and is only of value for one specific purpose.

In some cases animal models and in-vitro models are super-models of humans, because if humans were available for the experiment we would cull not to utilize them. For instance, if we desire to report some aspects of genetics we may choose a computer model, a fruit fly or a mouse. We know plenty almost genetics to be reasonably certain that the results tin be applied to humans, but our models are able to give results quickly and cheaply.

The similarities and differences between animals and humans are taken into business relationship when choosing a model

In trying to appraise the validity of animate being experiments it does not make sense to compile lists of differences between animals and humans, considering nosotros want them to be dissimilar in many ways. When studing obesity a mouse strain might be a good model of humans because it becomes obese, gets diabetes and dies young. The same strain may be useless in a long-term toxicity written report for exactly the same reasons. Each research project must give conscientious consideration to the choice of the specific model.

An instance: a model for the treatment of colon cancer

Colon cancer tin commonly be treated effectively unless information technology has already spread to the liver. By the time it is diagnosed this may have already happened, and by this stage it could exist inoperable. In this example, however, a new microwave probe, nigh the size of a pencil, has been developed. This could be inserted into tumours, assuasive a dose of microwaves to be applied, cooking the neoplasm and killing it.

The trouble was to determine the dose (volts) and fourth dimension required to cook a liver tumor of a given size with this probe. The experiments also needed to determine whether several tumours could exist treated in 1 patient, and what happened to an individual with some liver / tumor tissue killed in this way. Would it kill the patient? Clearly it would be both unethical and impractical to employ a human for these studies, even when terminally ill patients are available, and so an animal model was needed.

As the probe could not be scaled down, the creature model needed to take a liver of about the same size as a human. Rats were clearly unsuitable, but pigs were a more than appropriate selection. The pigs were anaesthetised, and ane or two areas of the liver treated with various doses of microwaves. Afterwards existence immune to recover the pigs were then killed at different time-points.

This research showed the dose of microwaves which is predicited to kill sus scrofa liver tissue of various diameters. The pigs were found to tolerate several lesions, and after two months the lesions had shrunk, although the animals were not kept long enough to discover whether they disappeared.

Clinical trials ensure that the model has worked successfully

There is no absolute assurance that the creature tests accurately predict human responses. Equally this was pig, not homo, liver and it was normal tissue, not a neoplasm, it is nevertheless necessary to do a minor clinical trial earlier widespread employ. If the prediction had been inaccurate, and then the start human patients would endure. Fortunately, the pig data was highly predictive of the homo results, and several terminally ill patients have now exist successfully treated and have left hospital apparently fully recovered.

With the development of new drugs the clinical trial is fourth dimension-consuming and expensive. With this simple surgical model there were some final cancer patients who it was estimated only had a few weeks to live, just were able and willing to requite informed consent. In this example it did non matter that the grunter differs from humans in many ways so long as the liver was about the aforementioned size as the human liver, and it responds in a like way to microwaves.

Alternatives that replace the use of animals are besides used as models

Most of the replacement alternatives to the use of animals are models of the same sort. They resemble some very specific homo features, but differ in many other ways. As an example, in early human pregnancy at that place is a surge of hormones affecting the uterus. Many years ago pregnancy was diagnosed using an animal model. A sample of urine was injected into some mice and the increase in uterus weight measured, or into frogs which and so ovulated if the woman was pregnant. Now this can be modelled in a home pregnancy testing kit.