about electron microscopes. I was surprised to hear that the resolution
of these instruments could be as small as nanometer (1X10e-9 m).
After talking about the turkey tail mushroom, I wondered how a
different scale of photography on the subject I had just presented might
look. Below is an electronic picture ofthe spores of the Turkey Tail
(Trametes Versicolor).
The small dark bar on the lower right side is 1um (1X10e-6 m). This
is almost at the limit of visible light photography; the limit of their
resolution is 0.2 um. With visible light, the pictures above would look
grainy, and would certainly loose the definition possible with the electron
microscope. In my presentation, I also mentioned that the extract of the
Turkey Tail is going through medical trials for possible applications in
cancer treatment. I could not find the compound under study
(polysaccharide-K), but I was able to find an electron microscope
photograph of a crystal of a different polysaccharide:
Looking at pictures at the boundary of visible light did not feel
unusual. After all, I could imagine taking ever more potent lenses
to see smaller pictures. But then I also realized that as the pictures
got finer and finer, I was crossing a boundary. The electron
microscope offers a picture of something no combination of lenses
can offer to the human eye. In that aspect, the electron microscope
is akin to a new sense, and the pictures although they look real and
objective, are really one step removed from our idea of reality. In
other words, the instrument is helping me see a structure to which
hitherto I only had access to in an abstract way. After all, the
picture above is a group of the molecule below, which is really
just a symbol to describe a molecule, and with the electron microscope,
this symbol becomes almost visible.
Danny W Chang
https://www.researchgate.net/figure/261284779_fig3_Figure-3-Chemical-structures-of-ginsenoside-Rg3-i-Rh2-j-and-polysaccharide-k
http://www.ijpsonline.com/articles/immunostimulant-activity-of-a-novel-polysaccharide-isolated-from-lactarius-deliciosus-l-ex-fr-gray.html
https://etd.ohiolink.edu/!etd.send_file?accession=miami1250269099&disposition=inline
is almost at the limit of visible light photography; the limit of their
resolution is 0.2 um. With visible light, the pictures above would look
grainy, and would certainly loose the definition possible with the electron
microscope. In my presentation, I also mentioned that the extract of the
Turkey Tail is going through medical trials for possible applications in
cancer treatment. I could not find the compound under study
(polysaccharide-K), but I was able to find an electron microscope
photograph of a crystal of a different polysaccharide:
Looking at pictures at the boundary of visible light did not feel
unusual. After all, I could imagine taking ever more potent lenses
to see smaller pictures. But then I also realized that as the pictures
got finer and finer, I was crossing a boundary. The electron
microscope offers a picture of something no combination of lenses
can offer to the human eye. In that aspect, the electron microscope
is akin to a new sense, and the pictures although they look real and
objective, are really one step removed from our idea of reality. In
other words, the instrument is helping me see a structure to which
hitherto I only had access to in an abstract way. After all, the
picture above is a group of the molecule below, which is really
just a symbol to describe a molecule, and with the electron microscope,
this symbol becomes almost visible.
Danny W Chang
https://www.researchgate.net/figure/261284779_fig3_Figure-3-Chemical-structures-of-ginsenoside-Rg3-i-Rh2-j-and-polysaccharide-k
http://www.ijpsonline.com/articles/immunostimulant-activity-of-a-novel-polysaccharide-isolated-from-lactarius-deliciosus-l-ex-fr-gray.html
https://etd.ohiolink.edu/!etd.send_file?accession=miami1250269099&disposition=inline
Thanks Danny, that is fascinating. FYI, I did a quick search on PubMed for "polysaccharide-K" and got 127 hits / articles. The "Abstract" and "Areas Covered" from the following article looked particularly relevant to your inquiries:
ReplyDelete"Abstract
INTRODUCTION:
Natural products (NPs) are evolutionarily designed and contain more complex and challenging structures than synthetic compounds. Since the 1980s, the pharmaceutical industry has gradually shifted to a strategy of developing targeted agents by screening libraries of synthetic compounds. However, NPs have recently received renewed focus as a rich repository for drug discovery. Irinotecan was developed as a derivative of camptothecin and was applied in standard regimens for metastatic colorectal cancer (CRC) worldwide. Additionally, polysaccharide K is approved for CRC in Japan and Taiwan in combination with cytotoxic agents. However, after the approval of irinotecan in 1996, no anti-cancer agents derived from NPs have been approved for CRC.
AREAS COVERED:
This review discusses NPs that are currently under investigation for the treatment of CRC. In addition, other NPs derived as purified ingredients and crude extracts are listed and also discussed."
See:
Martha McDaniel
The PubMed link is under PMID 25724579.
ReplyDeleteMartha