Posted by alexandra_k on August 10, 2013, at 20:39:51
In reply to Re: help, posted by Dr. Bob on August 10, 2013, at 0:50:15
> > Same niche... (Or perhaps not - perhaps they capture different markets, perhaps that is the solution).
> Overlapping niches? Like with antidepressants?
i never thought of antidepressants having overlapping niches...
> Consider the flourishing of the bacterium Staphylococcus aureus (MRSA) in the face of modern drug treatments:
> The story begins in 1943, when penicillin became the first widely used antibiotic. Since then, penicillin and other antibiotics have saved millions of lives. However, by 1945, more than 20% of the S. aureus strains seen in hospitals were already resistant to penicillin. These bacteria had an enzyme, penicillinase, that could destroy penicillin. Researchers responded by developing antibiotics that were not destroyed by penicillinase, but some S. aureus popultions developed resistance to each new drug within a few years.
>In 1959, doctors began using the powerful antibiotic methicillin, but within two years, methicillin-resistant strains of S. aureus appeared. How did these resistant strains emerge? Methicillin works by deactivating a protein that bacteria use to synthesize their cell walls. However, S. aureus populations exhibited variations in how strongly their members were affected by the drug. In particular, some individuals were able to synthesize their cell walls using a different protein that was not affected by methicillin. These individuals survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common, leading to the spread of MRSA.
>Initially, MRSA could be controlled by antibiotics that worked differently from methicillin. But this has become increasingly difficult because some MRSA strains are resistant to multiple antibiotics probably because bacteria can exchange genes with members of their own and other species (see Figure 27.13). Thus, the present-day multidrug-resistant strains may have emerged over time as MRSA strains that were resistant to different antibiotics exchanged genes (Reece et al., 2010, p. 462).
I suppose the different strains (with their different resistances) comprise different niches. And the different anti-biotics (with their different actions) comprise different niches, too).
I am becoming very attracted to the idea that: There isn't any such thing as species. There are just populations of individuals.
Why is the evolution of hysteria and the founder effect of a clinician setting up shop and finding his favorite dx all over the show thought to be somehow undermining of psychiatry's status as a field within medicine or a special application of biological science?
poster:alexandra_k
thread:1048661
URL: http://www.dr-bob.org/babble/social/20130612/msgs/1048766.html