University of Vermont

DE Matthews home page  
 Our motto: We Do Stable Isotopes Better
  Shown in the background is beautiful Mt. Mansfield, behind the University in the foreground (lovingly known as UVM*). The water tower forms a landmark for directions to other buildings.  Dr. Matthews' primary appointment is in Medicine in the College of Medicine, and he has a secondary appointment in Chemistry in the College of Arts & Sciences.  Both campuses can be seen in the photo, and links are provided on the left to both departments as well as a link to a campus map of UVM and directions to get to us.
Due to construction at the UVM Medical College  campus and renovation of the Given building, our location has changed from the Given Building to the Cook Building.
Our mailing address is now:
University of Vermont, Chemistry Dept., Cook Bldg, Burlington, VT 05405
What do we do?
 
  • We use mass spectrometry to measure stable isotopically labeled compounds. With these compounds we study metabolism in humans.
  • Stable isotopes are not radioactive, and they occur naturally in nature. For example, 99% of all carbon in the world is carbon-12 (12C) and 1% is carbon-13 (13C). We purchase enriched stable isotopes that have been placed into compounds in abundances much greater than their natural abundance. We can obtain labeled compounds with now 90-99% 13C.
  • A mass spectrometer will distinguish isotopes because it measures the abundance of compounds and elements by mass. Because 13C is 1 Dalton (or atomic mass unit) heavier than 12C, a 13C-labelled compound can be distinguished by mass spectrometry from an unlabeled compound.
  • We also use the isotopes of hydrogen: protium (1H) and deuterium (2H), nitrogen (14N and 15N) and oxygen (16O, 17O, & 18O).
  • We have both IRMS and GCMS instruments. In addition we have a hybrid GC-C-IRMS instrument. All of these instruments are used specifically to measure stable isotopic enrichments. Dr. Matthews constructed and tested the first GC-C-IRMS instrument for measuring 13C & 15N in biological compounds.
  • We administer stable isotopically labeled compounds to humans as tracers to define the rates of production, disposal and conversion of metabolites in the body. Using these tracers we can determine, for example, how much glucose the liver is making at any point in time, how much protein is being broken down in the body and how much of each amino acid is being released from this breakdown. We can tell whether the amino acids released from protein breakdown are reused for synthesis into new protein or are oxidized to CO2 by measuring the 13CO2 enrichment in a person's breath after a 13C-labelled tracer amino acid has been infused.
Measuring stable isotopic enrichments in biological compounds is not simple:
 
  • Mass spectrometry, which is used to measure stable isotopes, comes in different forms--all expensive and complex instrumentation.
  • In most cases, biological samples require isolation and chemical derivatization steps before they are suitable for measurement by mass spectrometry.
  • Designing experiments and labeled compounds to measure a specific metabolic event in the body is not simple.

As analytical chemists,
 
  • We develop new techniques in mass spectrometry to measure stable isotopically labeled compounds in humans in new, more precise, and more sensitive ways.
  • We develop new methods of sample isolation and derivatization.
  • We develop kinetic models to understand tracer metabolism in the body.
As clinical scientists in medicine,
 
  • We study how amino acid, glucose, and fat metabolism are regulated in humans.
    • We study how hormones regulate metabolism.
    • We study how metabolism is altered in different metabolic diseases, such as obesity and diabetes.
  • We are interested in nutrition and how the gut and liver metabolize dietary amino acids.
    • What amino acids are important to be in clinical nutrition solutions for hospitalized patients and why?
  • We are interested in metabolic changes with aging and menopause
    • What causes loss of muscle protein and strength with increasing age or during and after menopause?
    • How can we retain muscle protein with increasing age or after menopause?
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The University of Vermont was founded in 1791. 
Its abbreviation, UVM, comes from Universitas Virdis Montis, Latin for "University of the Green Mountain."
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Last modified July 05 2001 07:57 PM

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