Stripping Down Science by Chris Smith, Dr Christorpher Smith Read Free Book Online Page A

accident to help a local dentist make the intellectual leap that was to catapult N 2 O into the domain of medicine. Horace Wells watched as one of the volunteers breathing the gas, a man named Samuel Cooley, staggered into some nearby benches and injured his leg. What intrigued Wells was that Cooley remained unaware of his injury until the effects of the gas wore off. Realising that N 2 O might possess painkilling qualities, Wells approached the demonstrator, a medical school dropout called Gardner Quincy Colton, and invited him to participate in an experiment the next day.
    Colton agreed and subsequently administered nitrous oxide to Dr Wells while another dentist extracted one of Wells’ teeth. Wells experienced no pain during the procedure, and the birthof N 2 O as a dental and medical painkiller had arrived. That’s the history of the gas. Since that time, it’s been embraced as a safe agent that can be used for pain relief (such as during childbirth and dental procedures) and in general anaesthesia. On its own, it’s not a sufficiently potent anaesthetic to induce (i.e. cause) anaesthesia, but once a patient is ‘under’, it’s a very good gaseous agent for anaesthetic ‘maintenance’.
    In this respect, N 2 O isn’t that unusual, since most volatile gases can behave as anaesthetics with intoxicating effects – they differ only in their potency (i.e. how much of them is needed to have an effect). Volatiles with this property include the butane you squirt into your cigarette lighter and even petrol vapours. In fact, this latter example has been a serious problem in parts of Australia, where members of some communities have been sniffing petrol. This has resulted in BP (British Petroleum) recently producing a blend of unleaded for the Australian market that is less suitable for sniffing.
    No one knows exactly how general anaesthetics work, but the fact that they are usually organic, lipid-loving chemicals suggests that they probably alter nerve cell function by dissolving in the oilymembrane that surrounds our cells and affecting the behaviour of membrane pores or channels which control the excitability of the cell. Alcohol probably works similarly and there is now evidence that it specifically renders cells more sensitive to one of the brain’s inhibitory nerve transmitters called GABA. This means that cells become less responsive in the presence of alcohol, which is why booze is a central nervous system depressant.
    As an aside, it’s not just animals that can benefit from the effects of N 2 O. Cars receive a boost in performance when a burst of ‘nitro’ is injected into the cylinder during combustion. The heat of the burning fuel causes the nitrous oxide to decompose to nitrogen and oxygen: 2N 2 O -> 2N 2 + O 2 . So two molecules of gas turn into three molecules of gas, which increases the volume of products inside the cylinder, boosting performance. A bit like Viagra really, although that relies initially on the effects of nitric oxide (NO), rather than nitrous!

When American surgeon and Nobel laureate Joseph Murray performed the world’s first kidney transplant in December 1954, he was successful largely because the recipients, Richard and Ronald Herrick, were identical twins. Because the brothers shared the same DNA code, their individual immune systems could not distinguish the organs of one man from the other and so there was no question of rejection.
    Unfortunately, the majority of the 6.8 billion people currently alive on earth aren’t lucky enough to have an identical twin from whom to beg or borrow an organ whenever they need one. Even if they did, it’s unlikely that organs like the heart, of which most normal people have just one, would be volunteered willingly. As a result, the majority of the transplants carried out today are ‘allografts’. That is, they involve organs taken from someone who is genetically different fromthe