Intestinal ischemia whether resulting from emboli, thrombosis or strangulation obstruction continues to be a serious and potentially fatal condition. We have pioneered the use of Superconducting Quantum Interference Device (SQUID) magnetometers for biomagnetic recordings of gastrointestinal smooth muscle activity in vitro, and in both animal and human subjects. This non-invasive, non-contact measurement of biomagnetic currents in smooth muscle demonstrates the feasibility of using SQUIDs to investigate human intestinal smooth muscle physiology. SQUIDs have unique fundamental advantages over cutaneous electrode recordings of intestinal electrical activity because magnetic fields readily penetrate layers of fat while electrical fields do not and cutaneous electrode recordings of human small bowel can not be routinely obtained. SQUIDs represent a striking new diagnostic device that has no equivalent except for invasive surgery and placement of electrodes onto the bowel surface. Hypothesis 1: Mesenteric ischemia causes uncoupling and arrhythmias of intestinal smooth muscle detectable in externally recorded magnetic fields. We will develop models to explain the arrhythmias, uncoupling and the effects of intervening tissue on the externally recording magnetic fields. Advanced analysis techniques to discriminate ischemic bowel from normal signals will be developed base upon our knowledge of smooth muscle behavior during ischemia. We will characterize for the fist time the magnetic currents in recordings taken during and after surgical exploration. Hypothesis w: Mesenteric ischemia causes sustained polarization of affected smooth muscle cells resulting in injury currents detectable in the externally recorded magnetic fields. Injury currents have been previously demonstrated to occur and be detectable magnetically in cardiac animal and human studies to detect this phenomenon. The new multichanel SQUID specifically designed for study of human intestinal magnetic fields developed and built as part of a SBIR grant will be available for use and will give us an extraordinary opportunity for the first time to explore smooth muscle pathophysiology during intestinal ischemia-one of the most deadly diseases known to man.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK058197-01A1
Application #
6436637
Study Section
Special Emphasis Panel (ZRG1-SSS-X (11))
Program Officer
Hamilton, Frank A
Project Start
2002-02-15
Project End
2006-01-31
Budget Start
2002-02-15
Budget End
2003-01-31
Support Year
1
Fiscal Year
2002
Total Cost
$332,716
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Surgery
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Somarajan, S; Muszynski, N D; Cheng, L K et al. (2015) Noninvasive biomagnetic detection of intestinal slow wave dysrhythmias in chronic mesenteric ischemia. Am J Physiol Gastrointest Liver Physiol 309:G52-8
Somarajan, S; Cassilly, S; Obioha, C et al. (2014) Effects of body mass index on gastric slow wave: a magnetogastrographic study. Physiol Meas 35:205-15
Somarajan, Suseela; Cassilly, Summer; Obioha, Chibuike et al. (2013) Noninvasive biomagnetic detection of isolated ischemic bowel segments. IEEE Trans Biomed Eng 60:1677-84
Erickson, Jonathan C; Velasco-Castedo, Raisa; Obioha, Chibuike et al. (2013) Automated algorithm for GI spike burst detection and demonstration of efficacy in ischemic small intestine. Ann Biomed Eng 41:2215-28
Kim, J H K; Pullan, A J; Bradshaw, L A et al. (2012) Influence of body parameters on gastric bioelectric and biomagnetic fields in a realistic volume conductor. Physiol Meas 33:545-56
Somarajan, S; Muszynski, N D; Obioha, C et al. (2012) Biomagnetic and bioelectric detection of gastric slow wave activity in normal human subjects--a correlation study. Physiol Meas 33:1171-9
Kim, J H K; Bradshaw, L A; Pullan, A J et al. (2010) Characterization of gastric electrical activity using magnetic field measurements: a simulation study. Ann Biomed Eng 38:177-86
Erickson, Jonathan C; O'Grady, Gregory; Du, Peng et al. (2010) Falling-edge, variable threshold (FEVT) method for the automated detection of gastric slow wave events in high-resolution serosal electrode recordings. Ann Biomed Eng 38:1511-29
Irimia, Andrei; Swinney, Kenneth R; Wikswo, John P (2009) Partial independence of bioelectric and biomagnetic fields and its implications for encephalography and cardiography. Phys Rev E Stat Nonlin Soft Matter Phys 79:051908
Bradshaw, L A; Irimia, A; Sims, J A et al. (2009) Biomagnetic signatures of uncoupled gastric musculature. Neurogastroenterol Motil 21:778-e50

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