SHEILA Brennan (LET, December 26) is very loud in attacking medical research, but is remarkably quiet when it boils down to telling us what we should use instead of animals to give hope to people with serious illnesses.

We'd be interested to hear how he plans to replicate a beating heart, blood system, breathing lungs, central nervous system and the way these function together.

These are some of the necessities required by medical researchers when studying medical conditions.

Some things cannot be done using non-animal methods such as measuring blood pressure.

I fail to see why medical researchers would use animals if it wasn't necessary and to correct your correspondent's theory it's actually cheaper not to use them, which is why most research doesn't use animals. They are only used where no alternative exists.

There is nothing moral about denying patients essential medical treatments that were developed through animal research.

It would be consistent with their beliefs if anti-vivisectionists denied themselves such treatments, but usually they do not.

Moreover in campaigning to abolish all animal research, they seek to deny all of us the benefits of future treatments that are being researched today using animals.

The fact is: no animal research means no new medicines, the choice is as simple as that.

I'd like to thank the medical research community for saving my mother's life. It's time we all stood up and showed our gratitude for the huge contribution modern medicine has given us.

Patients' rights should be put on the map and a balanced argument put forward for humane animal research because it's our lives at stake.

Medical progress is being hampered by vocal and sometimes violent protests against animal research and genetic technology.

If the development of new therapies is threatened then our future health is at risk.

The voice of patients is important for the future of medical research.

Seriously Ill for Medical Research (SIMR) is a patients' group which supports the humane use of animals and genetic technology where necessary in medical research.

THOMAS BROMLEY, SIMR Executive Secretary, PO Box 504, Dunstable, Bedfordshire.