Metabolic Phenotyping

NExT offers an array of more general phenotyping tests to support research projects. These include: anthropometery and body composition analysis, resting metabolic rate, assessments of insulin sensitivity and glucose tolerance, systemic substrate kinetics, and tissue-specific analysis.

Anthropometry and Body Composition

Core staff members have completed extensive technical and clinical training and can conduct assessments in infants through the elderly as well as in a wide variety of special populations. We can conduct assessments for you, and/or can train your team to complete assessments per standard protocols. NExT intra- and inter-tester variability within repeatability trials are available upon request (we can also teach your study team how to do this within your group). NExT also offers skinfold, circumference and standard anthropometric assessments. The latter three assessments can easily be incorporated into many study protocols - including community-based research.

Dual-energy X-ray absorptiometry (DXA) utilizes a very low level of radiation (less than that to which you are exposed on a flight from east to west coast of the US) and requires that participants remain still on an open table for about twenty minutes. It provides a three-compartment model of body composition (fat mass, bone mass, lean mass) as well as regional composition (i.e. trunk, arms, legs, etc.).  We have successfully tested babies through elderly individuals. This technology is now considered by many to be a “gold standard” in body composition analysis and bone density measurement. The DEXA machine is a GE Lunar Prodigy ADVANCE Plus and is located at the CVC MCRU site.

If you would prefer a radiation-free option and/or one that does not require that participants remain still for quite as long, MNORC also measures body composition via air-displacement plethysmography.  In this two-compartment model of body composition (fat mass, fat-free mass), participants sit in an enclosed system with a large window for only a few minutes at a time.  We can assess newborns and infants (1kg – 8kg body weight) in our PEA POD, toddlers and young children in our BOD POD with the assistance of pediatric attachments (similar to a high-chair) and children through older adults in the standard BOD POD system. The BOD POD is located in Lobby M of Domino’s Farms, and the PEA POD is located near the NICU in Mott.

NExT staff includes a trained DEXA (dual energy x-ray absorptiometry) technician. This technology is now considered by many to be a “gold standard” in body composition analysis and bone density measurement. The DEXA machine is a GE Lunar Prodigy ADVANCE Plus and is located at the CVC MCRU site.

NExT staff are trained to conduct air-displacement plethysmography (Bod Pod) assessments for body composition. The Bod Pod is located at the Dominos Farms site.

Resting Metabolic Rate

The NExT staff can assess resting energy expenditure in adult and some pediatric populations using an Indirect Calorimetry System with both mouthpiece/nose clip and canopy attachments to facilitate measurement at either the CVC MCRU or the Dominos Farms site.

Assessments of Insulin Sensitivity and Glucose Tolerance

NExT staff are trained to perform an array of measurements to assess insulin sensitivity. These techniques include: hyperinsulinemic-euglycemic clamps, intravenous glucose tolerance tests (IVGTT), oral glucose tolerance tests (OGTT), and mixed meal Tolerance Tests (MMTT). These procedures can be performed in the CVC MCRU site.  Importantly, while the NExT staff can conduct these testing procedures, the study teams will need to provide an MD, RN, or NP on-site to be present during the administration of insulin, and they will need to outsource the measurements of plasma glucose and insulin concentrations. (These assays can be performed through the Michigan Diabetes Research Center’s “Clinical Core”). NExT can use these measures of plasma glucose and insulin concentration to provide summarized calculations of insulin sensitivity, glucose tolerance, and/or meal tolerance for each of your participants.

Systemic Substrate Kinetics

We can quantify the following physiologic measures in your participants using stable isotope tracer infusion methodology and gas chromatograph mass spectrometry analysis.

  • Hepatic glucose production (Glucose Ra)
  • Systemic glucose uptake (Glucose Rd)
  • Whole-body lipolytic rate (Glycerol Ra)

Tissue-Specific Analysis

We can assist your project by performing subcutaneous adipose tissue and/or skeletal muscle tissue (vastus lateralis) biopsies. After collecting the tissue samples, they will be frozen and stored at -80°C – ready for pick-up by your study team. NExT staff can also perform microdialysis procedures to quantify local metabolism within skeletal muscle and adipose tissue in vivo. All of these procedures must be performed in the CVC MCRU site.

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