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Research

MMRU-Body-Composition Request Procedures

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1. Sign up procedure for using the PIXImus.
The PIXImus is housed in the CNRF. When you wish to use it, please send an e-mail to Dr. Marta Fiorotto (martaf@bcm.edu) stating your approved animal protocol number, charge source, when you wish to use it, for how long, and if you have used the instrument before or need instruction. You will receive approval by e-mail. At the scheduled time, you will meet Dr. Fiorotto in the CNRF who will direct you to the instrument and assist with measurements. After you have finished using the instrument sign the log book entering all the requested information. Clean the PIXImus after you have completed your measurements and make sure you take your data with you. Your reservation will be logged onto the MMRU calendar.

2. Sign up procedure for using the QMR.
The QMR instrument is housed in the MMRU suite in the CNRF. When you wish to use it, send a request to Dr. Marta Fiorotto (martaf@bcm.edu) stating your approved animal protocol number, charge source, and if you have used the instrument before or need instruction. You will receive approval by e-mail. If you need instruction you will receive directions on how to set this up. Once you have received instructions and are cleared to operate the instrument by yourself, you will be given access to the booking calendar.

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Description of Body Composition Measurements:

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Dual X-ray Absorptiometry: Total body fat, lean, and bone mineral content will be measured by dual x-ray absorptiometry (DXA) using a PIXImus instrument (General Electric). The measurements are performed in a CNRF procedure room. Each mouse will be lightly anesthetized and placed on a disposable PIXImus measuring tray for proper alignment. The mouse will be inserted into the instrument for measurement (approx. 5 minutes) and then returned to its cage to recover. Anesthesia will be induced by placing the mouse in a chamber with isoflurane (5% and 95% oxygen). As soon as they are sedated they will be placed on the PIXImus instrument with a loosely-fitted nose cone containing isoflurane (2% isoflurane) until the measurement is complete. (or whatever your anesthesia of preference).

Quantiative Magnetic Resonance (QMR): A QMR analyzer (Echo Medical, Houston, Texas) will be used to determine the fat and lean content of the mice. The instrument determines the extent to which the protons present in lean and fat tissue perturb a magnetic field. This has been calibrated so that the output can be interpreted in terms of fat and lean masses. The instrument is located in the CNRF. The technique is noninvasive, nondestructive, does not require that the animal be sedated and causes no pain or stress. To perform these measurements the mouse is placed in a plexiglass tube (6 cm in diameter and restrained to a length of approximately 5 cm according to the size of the mouse), and is placed in the instrument's magnetic field. Readings are taken over a period of two to four minutes, after which the mouse is removed and returned to its cage.