Geng-Qing Song

Spokane VA Medical Center, Spokane, Washington, United States

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Publications (28)245.59 Total impact

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    ABSTRACT: The aim of this study was to test the hypothesis that that a method of gastric electrical stimulation (GES) optimized to inhibit gastric motility was effective in reducing food intake in dogs. Female dogs with a gastric cannula and gastric serosal electrodes were studied in three experiments: (1) to determine the best parameters and locations of GES in inhibiting gastric tone, slow waves, and contractions in dogs;( 2) to investigate the reproducibility of the inhibitory effects of GES; and (3) to study the effect of the GES method on food intake in dogs. (1) For GES to exert significant effects on gastric motility, a pulse width of ≥2 ms was required, and with other appropriate inhibitory parameters, GES was able to increase gastric volume by 190.4 %, reduce antral contractions by 39.7 %, and decrease the percentage of normal slow waves by 47.6 %. In addition, the inhibitory effect of GES was more potent with the stimulation electrodes placed along the lesser or greater curvature than placed in the middle, and more potent with the electrodes placed in the distal stomach than in the proximal stomach; (2) the inhibitory effects of GES on gastric motility were reproducible; (3) the GES method optimized to inhibit gastric motility produced a 20 % reduction in food intakes in non-obese dogs. GES with appropriate parameters inhibits gastric motility, and the effects are reproducible. The GES method optimized to inhibit gastric motility reduces food intake in healthy dogs and may have a therapeutic potential for treating obesity.
    Obesity Surgery 11/2014; 25(6). DOI:10.1007/s11695-014-1491-8 · 3.74 Impact Factor
  • Gastroenterology 05/2014; 146(5):S-852. DOI:10.1016/S0016-5085(14)63096-1 · 13.93 Impact Factor
  • Gastroenterology 05/2014; 146(5):S-843. DOI:10.1016/S0016-5085(14)63067-5 · 13.93 Impact Factor
  • Geng-Qing Song, Jiande D Z Chen
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    ABSTRACT:   The aim of this study was to systematically evaluate and compare the effects of synchronized dual-pulse gastric electrical stimulation (SDPS) and conventional gastric electrical stimulation (CGES) on antral contractions, gastric tone, and autonomic functions.   Seven female hound dogs implanted with four pairs of electrodes on gastric serosa were studied in two separate experiments. The first experiment was designed to investigate the effects of SDPS/CGES on gastric tone and heart rate variations. The second experiment was performed to study the effects of SDPS/CGES on antral contractions.   1) SDPS induced gastric antral contractions in the fasting state, whereas CGES at the intrinsic or a tachygastrial frequency had no effects on fasting antral contractions. 2) SDPS enhanced postprandial antral contractions impaired by glucagon; however, CGES at a tachygastrial frequency inhibited postprandial antral contractions. In addition, CGES at the intrinsic frequency of the stomach had no effects on postprandial antral contractions. 3) SDPS or CGES at the intrinsic frequency of the stomach had no effects on gastric tone, but CGES at a tachygastrial frequency reduced gastric tone. 4) SDPS excited vagal activity, but CGES at a tachygastrial frequency inhibited vagal activity.   SDPS improves antral contractions but does not affect gastric tone and thus may have potential for treating gastric motility disorders. CGES at a tachygastrial frequency inhibits gastric tone and contractions and may be applicable for treating obesity. The excitatory or inhibitory effects of SDPS/CGES on gastric motility may be mediated via vagal pathway.
    Neuromodulation 05/2011; 14(3):271-7; discussion 277. DOI:10.1111/j.1525-1403.2011.00338.x · 1.79 Impact Factor
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    ABSTRACT: The aim of this study was to investigate the effects and mechanisms of gastric electrical stimulation (GES) on proximal stomach distention-induced visceral sensitivity. Isobaric gastric distention was performed using a barostat system in 8 normal and 6 vagotomized dogs and animal behaviors were noted and graded. The normal dogs were studied in 4 sessions: control (no GES), short pulse GES, long pulse GES, and dual-pulse GES, and the vagotomized dogs were studied in three sessions: control (no GES), long pulse GES and guanethidine. It was found that: 1) proximal stomach distention-induced behavioral changes were mediated by vagal and sympathetic pathways. The total behavior score (TBS) was 40.6 ± 7.4 in the controls, 15.3 ± 8.9 in vagotomized dogs (P=0.006 vs. control) and 8.8 ± 0.9 in the vagotomized dogs with guanethidine (P=0.04 vs. vagotomy). The behavioral changes were mediated via the vagal pathway at distention pressures below 20 mmHg, but mediated via both the vagal and sympathetic pathways at distention pressures equal to and above 20 mmHg. 2) GES with long pulses or dual pulses but not short pulses reduced the distention-induced behavioral score (P=0.003, P=0.006 and P=0.7, respectively) and the effects of GES of long pulses might be mediated via the vagal and sympathetic pathways. In conclusion, gastric distention-induced visceral sensitivity is mediated via the vagal pathway at low distention pressures but via both vagal and sympathetic pathways at high distention pressures. GES with long but not short pulses reduces distention-induced visceral sensitivity.
    Autonomic neuroscience: basic & clinical 02/2011; 160(1-2):16-20. DOI:10.1016/j.autneu.2010.10.009 · 1.37 Impact Factor
  • Geng-Qing Song, Jiande Chen
    Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)60132-7 · 13.93 Impact Factor
  • Geng-Qing Song, Jiande Chen
    Gastroenterology 05/2010; 138(5). DOI:10.1016/S0016-5085(10)61440-0 · 13.93 Impact Factor
  • Geng-Qing Song, Chao Qin, Yan Sun, Jiande Chen
    Gastroenterology 05/2010; 138(5). DOI:10.1016/S0016-5085(10)63280-5 · 13.93 Impact Factor
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    ABSTRACT: Aims:  The aim of this study was to investigate and compare effective parameters for gastric electrical stimulation (GES) to modulate gastric muscle functions in different species. Methods:  Four species: Pigs, dogs, rats, and mice implanted with two pairs of electrodes on the serosal surface of the stomach were studied, respectively. Experiment 1 was designed to entrain/pace gastric slow waves and included a series of 5-min periods with long-pulse GES of different pulse widths and frequencies. Experiment 2 was designed to induce gastric dysrhythmia with long-pulse GES of different frequencies. Gastric slow waves were recorded during the entire experiment. Results:  1) The minimum pulse width for GES to completely entrain the slow waves was similar (100-400 msec) in all four species. 2) With fixed amplitude (4 mA) and pulse width (400 msec), the highest frequency at which slow waves could be paced was similar (about 10-60% higher than the intrinsic slow wave frequency) in all species. 3) With fixed pulse width of 400 msec and amplitude of 6 mA, GES with nine to 18 cycles per min (cpm) was able to induce dysrhythmia in dogs. In addition, there was no significant difference among these frequencies of 9-18 cpm. 4) GES with 400 msec, 6 mA, and 9 cpm was able to induce dysrhythmia in all species. These effective GES parameters in results 1-4 were similar to those used in humans in the literature. Conclusions:  There is no significant difference in stimulation parameters when GES is applied to alter gastric slow waves in different animal models. Furthermore, the effective parameters for GES to alter slow waves are similar between the humans and various animal models. These findings suggest that stimulation parameters obtained from animal studies are applicable in humans.
    Neuromodulation 04/2010; 13(2):87-92. DOI:10.1111/j.1525-1403.2009.00241.x · 1.79 Impact Factor
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    ABSTRACT: The aims of this study were to determine optimal pacing parameters of electrical stimulation on different gut segments and to investigate effects and possible mechanisms of gastrointestinal electrical stimulation on gut slow waves. Twelve female hound-mix dogs were used in this study. A total of six pairs of electrodes were implanted on the stomach, duodenum, and ascending colon. Bilateral truncal vagotomy was performed in six of the dogs. One experiment was designed to study the effects of the pacing frequency on the entrainment of gut slow waves. Another experiment was designed to study the modulatory effects of the vagal and sympathetic pathways on gastrointestinal pacing. The frequency of slow waves was 4.88 +/- 0.23 cpm (range, 4-6 cpm) in the stomach and 19.68 +/- 0.31 cpm (range, 18-22 cpm) in the duodenum. There were no consistent or dominant frequencies of the slow waves in the colon. The optimal parameters to entrain slow waves were: frequency of 1.1 intrinsic frequency (IF; 10% higher than IF) and pulse width of 150-450 ms (mean, 320.0 +/- 85.4 ms) for the stomach, and 1.1 IF and 10-20 ms for the small intestine. Electrical stimulation was not able to alter colon slow waves. The maximum entrainable frequency was 1.27 IF in the stomach and 1.21 IF in the duodenum. Gastrointestinal pacing was not blocked by vagotomy nor the application of an alpha- or beta-adrenergic receptor antagonist; whereas the induction of gastric dysrhythmia with electrical stimulation was completely blocked by the application of the alpha- or beta-adrenergic receptor antagonist. Gastrointestinal pacing is achievable in the stomach and small intestine but not the colon, and the maximal entrainable frequency of the gastric and small intestinal slow waves is about 20% higher than the IF. The entrainment of slow waves with gastrointestinal pacing is not modulated by the vagal or sympathetic pathways, suggesting a purely peripheral or muscle effect.
    AJP Regulatory Integrative and Comparative Physiology 09/2009; 297(5):R1392-9. DOI:10.1152/ajpregu.00006.2009 · 3.53 Impact Factor
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    ABSTRACT: To investigate the effect of two-channel gastric electrical stimulation (GES) with trains of pulses on gastric emptying and slow waves. Seven dogs implanted with four pairs of electrodes and equipped with a duodenal cannula were involved in this study. Two experiments were performed. The first experiment included a series of sessions in the fasting state with trains of short or long pulses, each lasted 10 min. A 5-min recording without pacing was made between two sessions. The second experiment was performed in three sessions (control, single-channel GES, and two-channel GES). The stimulus was applied via the 1st pair of electrodes for single-channel GES (GES via one pair of electrodes located at 14 cm above the pylorus), and simultaneously via the 1st and 3rd channels for two-channel GES (GES via two pairs of electrodes located at 6 and 14 cm above the pylorus). Gastric liquid emptying was collected every 15 min via the cannula for 90 min. GES with trains of pulses at a pulse width of 4 ms or higher was able to entrain gastric slow waves. Two-channel GES was about 50% more efficient than single-channel GES in entraining gastric slow waves. Two-channel but not single-channel GES with trains of pulses was capable of accelerating gastric emptying in healthy dogs. Compared with the control session, two-channel GES significantly increased gastric emptying of liquids at 15 min (79.0% +/- 6.4% vs 61.3% +/- 6.1%, P < 0.01), 30 min (83.2% +/- 6.3 % vs 68.2% +/- 6.9%, P < 0.01), 60 min (86.9% +/- 5.5 % vs 74.1% +/- 5.9%, P < 0.01), and 90 min (91.0% +/- 3.4% vs 76.5% +/- 5.9%, P < 0.01). Two-channel GES with trains of pulses accelerates gastric emptying in healthy dogs and may have a therapeutic potential for the treatment of gastric motility disorders.
    World Journal of Gastroenterology 06/2009; 15(19):2406-11. · 2.43 Impact Factor
  • Yan Sun, Geng-Qing Song, Jieyun Yin, Jie Chen, Jiande Chen
    Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)63143-7 · 13.93 Impact Factor
  • Geng-Qing Song, Yong Lei, Robert A. Ross, Jiande Chen
    Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)63618-0 · 13.93 Impact Factor
  • Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)60600-4 · 13.93 Impact Factor
  • Yan Sun, Geng-Qing Song, Jiande Chen
    Gastroenterology 05/2009; 136(5). DOI:10.1016/S0016-5085(09)60209-2 · 13.93 Impact Factor
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    ABSTRACT: Rectal distension (RD) is known to induce upper gastrointestinal (GI) symptoms. The aim of this study was to investigate the effects and underlying mechanisms of RD on gastric slow waves (GSW) and motor activity and furthermore to investigate the effects and mechanisms of electroacupuncture (EA) on GSW and motor activity. Eight female hound dogs chronically implanted with gastric serosal electrodes and a gastric fistula were studied in six separate sessions. Antral motility, GSW, heart rate variability, and rectal pressure were evaluated for the above purposes. 1) RD at a volume of 120 ml suppressed antral motility significantly. Guanethidine blocked the inhibitory effect of RD. EA at ST36 was able to restore the suppressed antral contractions induced by RD (16.6+/-1.7 vs. 8.0+/-1.4, P<0.001). Naloxone partially blocked the effect of EA on antral contractions. 2) RD reduced the percentage of normal GSW from 98.8+/-0.8% at baseline to 76.1+/-8.6% (P<0.05) that was increased to 91.8+/-3.0% with EA. The effects of EA on the GSW were nullified by the presence of naloxone. 3) EA did not show any significant effect on rectal pressure, suggesting that the ameliorating effects of EA on RD-induced impaired gastric motility were not due to a decrease in rectal pressure. 4) EA increased the vagal activity suppressed by RD. In conclusion, RD inhibits postprandial gastric motility and impairs GSW in dogs, and the inhibitory effects are mediated via the adrenergic pathways. EA at ST36 is able to restore the RD-induced impaired GSW and motor activities, possibly by enhancing vagal activity, and is partially mediated via the opioid pathway. EA may have therapeutic potential for functional gastrointestinal disorders.
    AJP Gastrointestinal and Liver Physiology 09/2008; 295(3):G614-20. DOI:10.1152/ajpgi.90322.2008 · 3.74 Impact Factor
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    ABSTRACT: Although several pathophysiologic abnormalities have been noted in functional dyspepsia (FD), their pathogenesis is poorly understood. We hypothesized that chronic gastric hypersensitivity and gastric motor dysfunction seen in FD patients can be modeled in rats by transient gastric irritation during the neonatal period, a time of known neuronal vulnerability to long-term plasticity. Ten-day-old male rats received 0.2 mL 0.1% iodoacetamide (IA) in 2% sucrose daily by oral gavages for 6 days; controls received 2% sucrose. Rats in both groups were then followed to adulthood (8-10 weeks) at which point behavioral, visceromotor, and great splanchnic nerve responses to graded gastric balloon distention (GD; 20-80 mm Hg) and gastric motor function were tested. IA-treated rats exhibited hypersensitivity to GD in a dose-dependent manner, as compared with the control group. The threshold of afferent nerve activation was lower and nerve responses to GD were significantly increased in IA-treated rats. Although IA-treated rats ingested food at a lower rate, gastric emptying was not significantly different between IA and control groups. However, gastric accommodation was significantly reduced in the IA group. No significant gastric pathology was seen in hypersensitive adult rats compared with controls. These studies demonstrate that gastric irritation in the neonatal period can result in chronic gastric hypersensitivity and gastric motor dysfunction in adults even in the absence of significant detectable gastric pathology. Our results offer insight into the pathogenesis of chronic functional dyspepsia and provide a potential model for further study to this important clinical problem.
    Gastroenterology 07/2008; 134(7):2070-9. DOI:10.1053/j.gastro.2008.02.093 · 13.93 Impact Factor
  • Yan Sun, Geng-Qing Song, Jiande Chen
    Gastroenterology 04/2008; 134(4). DOI:10.1016/S0016-5085(08)60573-9 · 13.93 Impact Factor
  • Gastroenterology 04/2008; 134(4). DOI:10.1016/S0016-5085(08)62237-4 · 13.93 Impact Factor
  • Jie Chen, Geng-Qing Song, Jieyun Yin, Jiande Chen
    Gastroenterology 04/2008; 134(4). DOI:10.1016/S0016-5085(08)62504-4 · 13.93 Impact Factor

Publication Stats

104 Citations
245.59 Total Impact Points

Institutions

  • 2007–2014
    • Spokane VA Medical Center
      Spokane, Washington, United States
  • 2009
    • University of Texas Medical Branch at Galveston
      • Division of Gastroenterology and Hepatology
      Galveston, TX, United States
  • 2007–2008
    • Huazhong University of Science and Technology
      • Department of Gastroenterology
      Wu-han-shih, Hubei, China