n. doubling of the heart sounds, which may be heard in healthy individuals and shows variation with respiration due to the slightly asynchronous closure of the heart valves.
It has been known for many years that one VIRUS will interfere with the growth of another. In 1957, UK research workers isolated the factor that was responsible for the phenomenon, giving it the name of interferon. There are now known to be three human interferons. They are glycoproteins and are released from cells infected with virus or exposed to stimuli which mimic virus infection. They not only inhibit the growth of viruses; they also inhibit the growth and reduplication of cells, and this is the basis for their investigation as a means of treating cancer. Hitherto the major di?culty has been obtaining su?cient supplies of interferon, but methods have now been evolved which promise to provide adequate amounts of it. The most promising of these is by means of what is known as genetic engineering, or manipulation, whereby a portion of DNA from interferon is inserted into the micro-organism known as Escherichia coli (see ESCHERICHIA) which thus becomes a source of almost unlimited amounts of interferon as it can be grown so easily.
Interferon alfa – previously termed leucocyte interferon or lymphoblastoid interferon – has some antitumour e?ect in some solid tumours and lymphomas. It is also used to treat HEPATITIS B and C (chronic variety). Various side-effects include suppression of MYELOBLAST production. Interferon beta – previously termed ?broblast interferon – is used (under restricted conditions in the UK) to treat patients with relapsing, remitting MULTIPLE SCLEROSIS (MS), and interferon beta-16 is licensed for use in patients with the secondary progressive type of this disorder. The use of interferon, which has a range of side-effects, should be recommended by a neurologist.... interferon
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