Medicine??
Thursday, February 11th, 2010 at
2:31 pm
1-How did Alexander Fleming discover penicillin?
2-Why was it so difficult to make a medicine out of penicillin?
3-Who developed the industrial process which made it possible to mass-produce penicillin.
4-Why has it been so difficult to develop medicines against viruses than it has against bacteria?
Filed under: Alternative Medicine
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I’ll just add that viruses tend to co-opt the host cell’s enzymes, whereas bacteria tend to use their own. Therefore, since bacteria use different enzymes than our own cells, we can attack them without attacking our own cells. Not so with viruses. Many of the anti-viral medications we have also inhibit our own cells, because you are really just inhibiting our own enzymes. It’s similar to the problem of treating cancer–how to target the bad cells without getting the good ones. This is problematic because for the most part, they share all the same proteins that might be good targets.
Originally noticed by a French medical student, Ernest Duchesne, in 1896. Penicillin was re-discovered by bacteriologist Alexander Fleming working at St. Mary’s Hospital in London in 1928. He observed that a plate culture of Staphylococcus had been contaminated by a blue-green mold and that colonies of bacteria adjacent to the mold were being dissolved. Curious, Alexander Fleming grew the mold in a pure culture and found that it produced a substance that killed a number of disease-causing bacteria. Naming the substance penicillin, Dr. Fleming in 1929 published the results of his investigations, noting that his discovery might have therapeutic value if it could be produced in quantity.
By November 26, 1941, Andrew J. Moyer, the lab’s expert on the nutrition of molds, had succeeded, with the assistance of Dr. Heatley, in increasing the yields of penicillin 10 times.
Pumping air into deep vats containing corn steep liquor (a non-alcoholic by-product of the wet milling process) and the addition of other key ingredients was shown to produce faster growth and larger amounts of penicillin than the previous surface-growth method. Ironically, after a worldwide search, it was a strain of penicillin from a moldy cantaloupe in a Peoria market that was found and improved to produce the largest amount of penicillin when grown in the deep vat, submerged conditions.
As production was increased, the price dropped from nearly priceless in 1940, to $20 per dose in July 1943, to $0.55 per dose by 1946.
There are many reasons why it is difficult to manufacture an effective anti-viral vaccine, including:
* Repeated alteration of viral antigens so that they are not recognized by the immune system.
* Masking of viral antigens with normal host proteins.
* Viral proteins mimicking normal host proteins.
* Viral proteins blocking parts of the immune system, such as antigen presentation.
* Viral latency where there are only a small numbers of viruses present that do not damage the host cell.