Hello colleagues.
 
        Using the 543nm line of our Green HeNe laser, we have seen that our
colonic tissue has a suprisingly bright autofluorescence at about 600-620nm.
I am used to seeing autofluorescence in response to UV excitation (due
to NADH and FADH), but this is the first time I have picked up
autofluorescence at such red wavelengths. I have two items for discussion:
 
(1) The obvious question: what endogenous compounds are responsible for
the red fluorescence. Porphryins are the only compounds I know which
absorb at these wavelengths: do they fluoresce and if so at what
wavelengths? Any other candidate compounds to explain these observations?
 
(2) It would be helpful to have a listing/discussion of all the compounds
which contribute to autofluorescence at the wavelengths of excitation we
all use. Anyone care to mention the compounds they have worried
about most? It would be particularly helpful to know how to identify the
culprit in any given situation (eg. by adding metabolic inhibitors,
chelators, etc.).
 
Chip
 
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  Chip Montrose
   Johns Hopkins University     tel: 410-955-9681
    Ross 930                      FAX: (410) 955-9677
     720 Rutland Avenue            email: [log in to unmask]
      Baltimore, MD 21205
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