Gasp reflex linked to cot death

· Inability to restart breath might put babies at risk · Mechanism controlled by separate part of brain

Hormone raises hope of victory in war on obesity

· Rats' intake of food cut by half in research tests · Questions still remain, warns specialist

Male circumcision reduces HIV risk by 60%, says study

· Researchers believe virus attaches to foreskin cells· Men urged to keep practising safe sex

Researchers inflict pain in hope of easing suffering

· Subjects volunteer for shock and heat ordeals · Study could help diabetes and shingles sufferers

Animal organ trials ‘within five years’

Clinical trials using animal organs to keep humans alive may be just five years away, an expert has said.

What have guinea pigs ever done for us?

Millions of lives have been saved by animal experiments, say scientists. Vivienne Parry examines the key research.