Biomedical subjects

J D Z Chen

Publications and source records attributed to J D Z Chen.

At least 19 recordsLinked to original sources

PubMed2006

Electroacupuncture accelerates solid gastric emptying and improves dyspeptic symptoms in patients with functional dyspepsia.

The aims of this study were to investigate the effects of electroacupuncture (EA) at ST36 and PC6 points on solid gastric emptying and dyspeptic symptoms in patients with functional dyspepsia. Nineteen patients with functional dyspepsia (FD) were involved in the study, consisting of two parts: (1) acute effects of EA on solid gastric emptying in FD patients with delayed gastric emptying and (2) short-term (2-week) effects of EA on symptoms in FD patients with normal gastric emptying. Results were as follows. (1) Ten of the19 patients showed delayed gastric emptying of solids, and acute EA significantly improved delayed gastric emptying; the halftime for gastric emptying was reduced from 150.3+/-48.4 to 118.9+/-29.6 min (P=0.007). (2) In the nine patients with normal gastric emptying, 2-week EA significantly decreased the symptom score, from 8.2+/-3.3 at baseline to 1.6+/-1.1 (P < 0.001) at the end of treatment. We conclude that EA at the ST36 and PC6 points accelerates solid gastric emptying in FD patients with delayed gastric emptying and relieves dyspeptic symptoms in FD patients with normal gastric emptying.

Acupuncture Points↗

PubMed2006

Gastric electrical stimulation with parameters for gastroparesis enhances gastric accommodation and alleviates distention-induced symptoms in dogs.

Gastric electrical stimulation (GES) improves symptoms in patients with gastroparesis. We sought to determine if stimulation at fundus with parameters used for gastroparesis could affect gastric accommodation and distention-induced symptoms in dogs. Nine dogs were implanted with a gastric cannula at the anterior stomach and 1 pair of stimulation electrodes in the fundus. Assessment of gastric accommodation and a series of gastric distention were performed using a barostat. Stimulation parameters were of short pulse trains of 14 Hz, 5 mA, 0.3 ms, and 0.1 s on, 5 s off. GES at fundus significantly decreased fasting gastric tone. Fasting gastric volume was significantly increased from 56.3+/-10.4 mL at baseline to 102.4+/-23.1 mL with stimulation (P=.011). Postprandial gastric accommodation was significantly enhanced with stimulation. The extent of accommodation increased from 249.3+/-39.9 mL in the control session to 325.8+/-25.1 mL with stimulation (P=.011). Symptom scores induced by balloon distention of the stomach were significantly lower during stimulation in comparison with those of baseline (P=.016). In conclusion, GES with parameters for gastroparesis enhances postprandial gastric accommodation and reduces visceral perception in normal dogs. This effect, if seen also in humans, may explain in part the symptomatic improvement associated with GES therapy in patients with gastroparesis.

Animals↗

PubMed2006

Systematic review: applications and future of gastric electrical stimulation.

BACKGROUND: Over the past 20 years, gastric electrical stimulation has received increasing attention among researchers and clinicians. AIM: To give a systematic review on the effects, mechanisms and applications of gastric electrical stimulation. METHODS: Medline was used to identify the articles to be included in this review. Key words used for the search included gastric electrical stimulation, gastric pacing, electrical stimulation, stomach, gastrointestinal motility, central nervous system, gastroparesis, nausea and vomiting; obesity and weight loss. Combinational uses of these keywords were made to identify relevant articles. Most of the articles included in this review ranged from 1985 to 2006. RESULTS: Based on the general search, the review was structured as follows: (i) peripheral and central effects and mechanisms of gastric electrical stimulation; (ii) clinical applications of gastric electrical stimulation for gastroparesis and obesity and (iii) future development of gastric electrical stimulation. CONCLUSIONS: Great progress has been made during the past decades. Gastric electrical stimulation has been shown to be effective in normalizing gastric dysrhythmia, accelerating gastric emptying and improving nausea and vomiting. Implantable device has been made available for treating gastroparesis as well as obesity. However, development of a new device and controlled clinical studies are required to further prove clinical efficacy of gastric electrical stimulation.

Animals↗

PubMed2006

Ghrelin improves burn-induced delayed gastrointestinal transit in rats.

Delayed gastrointestinal transit is common in patients with severe burn. Ghrelin is a potent prokinetic peptide. We aimed at testing the effect of ghrelin on burn-induced delayed gastrointestinal transit in rats. Gastric emptying (GE), intestinal transit (IT), and colonic transit (CT) studies were performed in male Sprague-Dawley rats. Rats were randomized into two main groups as follows: sham injury and ghrelin-treated burn injury with doses of 0, 2, 5, and 10 nmol/rat ip 6 h after burn. Sham/burn injury was induced under anesthesia. Rats received a phenol red meal 20 min following ghrelin injection. Based on the most effective ghrelin dose, 1 mg/kg sc atropine was given 30 min before the ghrelin in one group of rats for each study. The rats in each group were killed 30-90 min later; their stomachs, intestines, and colons were harvested immediately, and the amount of phenol red recovered was measured. Percentage of gastric emptying (GE%) and geometric center for IT and CT were calculated. We found 1) severe cutaneous burn injury significantly delayed GE, IT, and CT compared with sham injury (P < 0.05); 2) ghrelin normalized both GE and IT, but not the CT; 3) the most effective dose of ghrelin was 2 nmol/rat; and 4) atropine blocked the prokinetic effects of ghrelin on GE% and IT. In conclusion, ghrelin normalizes burn-induced delayed GE and IT but has no effect on CT in rats. The prokinetic effects of ghrelin are exerted via the cholinergic pathway. Ghrelin may have a therapeutic potential for burn patients with delayed upper gastrointestinal transit.

Animals↗

PubMed2006

Systematic review: pathophysiology and management of gastrointestinal dysmotility in systemic sclerosis (scleroderma).

Gastrointestinal dysmotility in systemic sclerosis (scleroderma) is prevalent in 90% of patients, increasing morbidity and in some cases mortality. The resultant gastrointestinal complications are usually extensive, involving many regions of the gut from the oesophagus to the anus. Collagen replacement of vascular and enteric smooth muscle results in hypomotility, lumen dilatation, tensile rigidity and eventual loss of organ functions. The aim of this paper is to provide an overview of systemic sclerosis-related gastrointestinal dysmotility and available/potential therapeutic options. We evaluated published data on the pathophysiology and management of gastrointestinal dysmotility in systemic sclerosis patients using the MEDLINE database for English and non-English articles from 1966 to July 2005. Based on this systematic review, lifestyle and medical therapy approaches are preferred as they often improve and/or ameliorate symptoms. Surgery is only recommended with serious, rare complications such as bowel perforation or ischaemia. Alternative therapies such as acupuncture-based therapies are well tolerated, with clinical improvement and may be of potential therapeutic benefit for systemic sclerosis gastrointestinal dysmotility. Further elucidation of initiating and persistent mechanisms of systemic sclerosis-related gastrointestinal dysmotility will optimize the development of a multidisciplinary and more directed treatment regimen.

Colon↗

PubMed2006

Inhibitory effects and mechanisms of colonic electric stimulation on gastric and rectal tone in conscious dogs.

PURPOSE: Colonic electric stimulation has been shown to alter motor functions of the colon; however, its effects on other organs of the gut have been investigated rarely. METHODS: This study was performed in 12 dogs implanted with one pair of colonic serosal electrodes and a gastric cannula. Experiments were performed to study: 1) the effect of colonic electric stimulation on proximal gastric tone and compliance; 2) the effect of colonic electric stimulation on rectal tone and compliance; 3) the sympathetic mechanism involved in the effects of colonic electric stimulation on gastric/rectal tone. A computerized barostat was used to assess gastric/rectal tone and compliance. RESULTS: Colonic electric stimulation inhibited both gastric and rectal tone with a higher potency in gastric tone. Colonic electric stimulation reduced gastric but not rectal compliance. The inhibitory effect of colonic electric stimulation on gastric tone but not rectal tone was abolished by an adrenergic blockade, guanethidine. CONCLUSIONS: Colonic electric stimulation inhibits both gastric and rectal tone with a higher potency in inhibiting gastric tone. Colonic electric stimulation reduces gastric but not rectal compliance. The inhibitory effect of colonic electric stimulation on gastric tone seems to be mediated by the sympathetic pathway.

Adrenergic Agents↗

PubMed2006

Effects and mechanisms of anal electrical stimulation on anorectal compliance and tone in dogs.

PURPOSE: This study was designed to investigate the changes in rectal compliance and tone during anal electric stimulation and the involvement of the alpha-adrenergic pathway in conscious dogs. METHODS: Eight healthy dogs were studied in five randomized sessions. Anal sphincter pressure was quantified by using the area under the contractile curve. Rectal compliance and tone were measured in a pressure-controlled phasic and isobaric distention by using an electronic barostat. Anal electric stimulation was performed via a pair of ring electrodes attached to the catheter. RESULTS: The electric stimulation-induced increase in sphincter pressure was lowered by the presence of an alpha(1)-adrenergic receptor antagonist, prazosin (18.6 +/- 7.4 vs. 45.4 +/- 9.7, P < 0.05), or alpha(2)-adrenergic receptor antagonist, yohimbine (10.2 +/- 8.2 vs. 38.3 +/- 7.6, P < 0.05), compared with the control. The threshold volume in rectoanal inhibitory reflex during electric stimulation was significantly higher than during baseline (27.5 +/- 0.9 vs. 22.5 +/- 1.9 ml, P < 0.05). There were no significant differences between the percentage drops in sphincter pressure with and without stimulation at a rectal distention level of 45 ml of air. Anal electric stimulation significantly increased rectal compliance reflected as reduced P(1/2) (11.1 +/- 1.5 vs. 16.7 +/- 1.1, P = 0.027) and reduced kappa (11.6 +/- 2.5 vs. 20.5 +/- 2.6, P = 0.0095), compared with the control session, but did not significantly alter rectal tone. CONCLUSIONS: Anal electric stimulation increases anal sphincter pressure, mediated at least partially by the alpha-adrenergic pathway. It also increases rectal compliance but does not alter rectal anal inhibitory reflexes.

Adrenergic alpha-1 Receptor Antagonists↗

PubMed2006

Colonic electrical stimulation regulates colonic transit via the nitrergic pathway in rats.

Gastrointestinal electrical stimulation has been proposed for the treatment of gastrointestinal motor disorders. However, little is known about potential roles of colonic electrical stimulation (CES). The aim of this study was to evaluate the effect and mechanism of CES on colonic transit in conscious rats. Male rats (N = 14) were equipped with a pair of colonic serosal electrodes for stimulation and a catheter in the colon. Colonic transit was assessed in four randomized sessions with or without CES and with or without nitric oxide synthesis blocker, L-NNA, by calculating the output of phenol red from the anus every 10 min for 90 min. Results were as follows. (1) CES with trains of short pulses significantly enhanced colonic transit. Colonic emptying was 57.3 +/- 6.1% in the control session and 81.9 +/- 4.6% with CES at 90 min, reflecting a 43% increase. (2) L-NNA delayed colonic transit compared with saline and prevented the accelerative effect of CES on colonic transit. We conclude that CES has an excitatory effect on colonic transit and this excitatory effect may be mediated via the nitrergic pathway.

Analysis of Variance↗

PubMed2006

Inhibitory effects of sildenafil on small intestinal motility and myoelectrical activity in dogs.

Previous studies have shown that sildenafil inhibits the esophageal motility in both humans and animals. The aim of this study was to investigate the effects of sildenafil on intestinal myoelectrical activity and motility. The study was composed of 2 experiments and performed in 7 healthy female dogs with a duodenal cannula 20 cm beyond pylorus (19-26 kg). The first experiment was designed to study the effects of sildenafil on intestinal myoelectrical activity and it included 2 sessions each consisting of 30-minute baseline, 15-minute posttreatment (placebo or 100 mg sildenafil) and 90 minutes after a liquid meal. Intestinal myoelectrical activity was recorded during the entire experiment period. The second experiment was aimed to investigate the effect of sildenafil on intestinal motility and was performed immediately after a solid meal. Intestinal motility was measured by a manometric catheter inserted into the small intestine via the duodenum cannula for 30 minutes at baseline and 60 minutes after sildenafil. Sildenafil significantly reduced the amplitude but had no effect on the frequency and regularity of the intestinal myoelectrical activity. Sildenafil significantly inhibited postprandial intestinal contractions. Although the frequency of the contractions was not altered, the mean area under the curve was significantly reduced during the first 30 minutes (P < .03) and second 30 minutes after sildenafil (P < .03); the power of intestinal contractile activities was also significantly reduced during the first 30 minutes (P < .0004) and second 30 minutes after sildenafil (P < .0003) in comparison with baseline. In conclusion, sildenafil inhibits the amplitude of both intestinal contractile activity and intestinal slow waves.

Animals↗

PubMed2006

Roles of interstitial cells of Cajal in intestinal transit and exogenous electrical pacing.

The aims of this study were to investigate the role of interstitial cells of Cajal (ICCs) on small intestinal transit and its responses to exogenous pacing in W/W(v) mice. Eleven W/W(v) mice and their controls implanted with four pairs of gastrointestinal electrodes were used for testing the entrainment of slow waves. Another 20 W/W(v) mice and their controls equipped with a duodenal catheter and one pair of intestinal electrodes were used to test small intestinal transit represented by the geometric center (GC). Results were as follows. (1) The effect of pacing on slow wave frequency was sustained only in controls, and not in W/W(v) mice. (2) Both gastric and intestinal slow waves were completely entrained in controls and W/W(v) mice. Higher energy was required for pacing the stomach than the small intestine. (3) There was no significant difference in small intestinal transit between the controls and the W/W(v) mice (GC: 5.4 vs. 5.5). (4) Pacing showed no effects on small intestinal transit in either wild-type (GC: 5.4 vs. 5.6) or W/W(v) mice (GC: 5.5 vs. 5.7). We conclude that myenteric ICCs may not play an important role in the regulation of small intestinal transit in conscious mice. Gastric and intestinal pacing can be achieved without ICCs.

Animals↗

PubMed2006

Pacing the gut in motility disorders.

Similar to cardiac pacing, gastrointestinal (GI) pacing is an attractive idea and may become a promising therapy, as the GI organs, like the heart, have their own natural pacemakers. Over the past 10 years, electrical stimulation of the gut has received increasing attention among researchers and clinicians. Several clinical studies have shown that gastric electrical stimulation (GES) with short pulses is able to reduce nausea and vomiting in patients with gastroparesis and that GES with long pulses is able to pace the intrinsic gastric slow waves and thus normalize gastric dysrhythmia. However, possible placebo effects cannot be ruled out, although recent animal studies have revealed various peripheral and central mechanisms involved with GES. Electrical stimulation of the small intestine, colon, or anal sphincter also has been reported for the treatment of dumping syndrome, constipation, and fecal incontinency. Similarly, there is a lack of placebo-controlled studies. In our opinion, pacing of the gut has great potential for the treatment of various GI motor disorders. However, none of the commercially available devices is designed for pacing the gut. The lack of well-suited devices and the invasive nature of gut pacing slow down the progress and clinical applications of gut pacing.

Journal Article↗

PubMed2006

Neural mechanisms involved in the inhibition of intestinal motility induced by intestinal electrical stimulation in conscious dogs.

The effects and mechanisms of intestinal electrical stimulation (IES) with long pulses on intestinal motility were investigated in conscious dogs. Eighteen dogs were equipped with serosal electrodes and an intestinal cannula in the small bowel. The first experiment was designed to study the effect of one-channel IES on intestinal motility and the extent of this effect. The second experiment was conducted to study the effect of IES on intestinal motility and the involvement of neural pathway. The IES with long pulses significantly inhibited intestinal motility. Intestinal motility of the entire measured segment (40-220 cm distal to the stimulation electrodes) was inhibited by 60-74% with the single-channel IES with long pulses. Hexamethonium, guanethidine, phentolamine, propranolol partially, but not N(omega)-nitro-L-arginine (L-NNA), ondansetron and naloxone prevented the inhibitory effect of IES on intestinal motility. We conclude that single-channel IES inhibits intestinal motility within a distance of at least 2 m. This inhibitory effect induced by IES with long pulses is mediated via sympathetic but not nitrergic, serotoninergic 5-HT(3) and opiate pathway.

Animals↗

PubMed2006

Effects and mechanisms of long-pulse gastric electrical stimulation on canine gastric tone and accommodation.

Gastric electrical stimulation (GES) has been applied to treat gastroparesis and morbid obesity. The aims of this study were to evaluate the sites of stimulation and the mechanisms of GES on gastric tone and accommodation. Gastric tone and accommodation were evaluated with a barostat in surgically prepared dogs. GES was applied at seven different locations, and gastric tone was assessed at each site. The effect of truncal vagotomy on gastric tone and accommodation and the role of the nitrergic pathway were also evaluated. We have found: 1) GES induced varying degrees of gastric relaxation at all tested locations in normal dogs; 2) Gastric volume was also significantly increased with GES in vagotomized dogs and the change tended to be lower than that of normal animals; 3) Gastric accommodation was reduced during GES in both the normal and vagotomized dogs and the reduction tended to be more in the vagotomized animals; 4) The GES-induced increase in gastric volume was partially abolished by intravenous nitric oxide synthase inhibitor. GES at various sites of the stomach exerts inhibitory effect on gastric tone; the most effective sites are in the antrum along the lesser or greater curvature; the inhibitory effect of GES on gastric tone is partially mediated by the vagal and nitrergic pathway.

Animals↗

PubMed2006

Development of gastric slow waves and effects of feeding in pre-term and full-term infants.

The aims of this study were to investigate the difference in developmental process of gastric slow waves and the effects of feeding in pre-term and full-term infants. Twenty-six pre-term and 31 full-term infants were enrolled in the study. Gastric myoelectrical activity was recorded using electrogastrography (EGG) from birth to month 6. An increase in the % of 2-4 cpm slow waves was noted in both pre-term (P < 0.01) and full-term infants (P < 0.04) from birth to month 4. The pre-term infants showed a reduced dominant EGG power at certain points of the study. (3) Breast or formula feeding resulted in no difference in the EGG in the full-term infants and showed a difference in the postprandial dominant power of the EGG in the pre-term infants only at month 2 after birth (P < 0.05) but not at other times. The gastric slow wave in pre-term infants is of a significantly reduced amplitude but similar rhythmicity. The method of feeding has no effects on the EGG in full-term infants and minimal effects (may be of non-clinical significance) on the EGG in pre-term infants as the difference was noted only at one time point during the 6-month follow-up study.

Bottle Feeding↗

PubMed2006

Efficacy and efficiency of gastric electrical stimulation with short pulses in the treatment of vasopressin-induced emetic responses in dogs.

The aim of this study was to determine the most effective and efficient anti-emetic parameters of short-pulse gastric electrical stimulation (GES) in dogs. Seven female beagle dogs implanted with four pairs of gastric electrodes were studied in eight randomized sessions (saline, vasopressin, and six GES sessions with different parameters). Each session consisted of four 20-min recordings of gastric slow waves and symptoms. In sessions 1 and 2, saline and vasopressin, respectively, were infused during the second 20-min period. The protocol of the other six sessions was the same as session 2 except that GES was continuously applied. It was found that: (1) vasopressin induced gastric dysrhythmia and emetic response (P < 0.01, anova); (2) short-pulse GES with a frequency of 14 or 40 Hz and pulse width of 0.1 or 0.3 ms, but not 0.6 ms was able to reduce symptoms induced by vasopressin; (3) short-pulse GES with a pulse width of 0.3 ms was the most effective in preventing vasopressin-induced symptoms; (4) none of the tested GES methods improved vasopressin-induced gastric dysrhythmia. We conclude that vasopressin induces gastric dysrhythmia and symptoms. Short-pulse GES with a pulse width of 0.3 ms and frequency of 14 Hz is most effective and efficient in preventing vasopressin-induced emetic responses in dogs.

Animals↗

PubMed2006

Central mechanisms of gastric electrical stimulation involving neurons in the paraventricular nucleus of the hypothalamus in rats.

BACKGROUND: Gastric electrical stimulation (GES) has been shown to be effective in inducing satiety in patients with obesity, as well as in treating nausea and vomiting in patients with gastroparesis. It is conceivable that these effects are mediated via the central nervous system, although there is a lack of studies or evidences. The aims of this study were to investigate the effects of GES with different parameters on neurons in the paraventricular nucleus (PVN) of the hypothalamus and to study whether the neuronal response was related to stimulation parameters. METHODS: Extracellular potentials of single neurons in the PVN were recorded in anesthetized rats at baseline, during gastric distention (GD) and during GES with various sets of parameters. RESULTS: Of 115 PVN neurons tested by GD, 104 were GD-responsive neurons. Most of these GD-responsive neurons were responsive to GES of various parameters. 1) GES with parameters used in treating obesity, activated neurons both excited (GD-E) and inhibited (GD-I) by gastric distention; it excited 48.4% (16/33) of the GD-E neurons and 60.4% (29/48) of GD-I neurons. 2) GES with increased pulse width was of the highest efficacy in exciting the GD-responsive neurons, whereas a reduction in stimulation frequency resulted in a lower activation. 3) GES with parameters used in treating gastroparesis solicited neuronal responses opposite to those with parameters used for treating obesity. CONCLUSION: GES activates gastric-related neurons in the PVN, and the excitatory effect of GES seems related to stimulation strength. The GES used for treating gastroparesis and the GES used for treating obesity seem to solicit different neuronal responses in the PVN.

Animals↗

PubMed2006

Implantable gastric stimulation alters expression of oxytocin- and orexin-containing neurons in the hypothalamus of rats.

BACKGROUND: Implantable gastric stimulation (IGS) has been proposed as a therapeutic option for treating obese patients. We studied the underlying central mechanism behind the reduction of food intake and body weight by gastric electrical stimulation (GES), by studying the expression of anorexigenic and orexigenic-peptide containing neurons in the hypothalamus. METHODS: Oxytocin antiserum, orexin antiserum and c-Fos protein-antiserum were used for immunostaining technique. Brain sections were obtained from the control rats and those with 2 hours of GES with parameters typically used in the treatment of obesity in humans. RESULTS: A) 2-hr IGS increased the expression of oxytocin-immunoreactive (IR) neurons in the paraventricular nucleus (PVN, 23.7+/-1.8 vs 31.1+/-2.2, P<0.05) and the supraoptic nucleus (SON, 29.0+/-2.2 vs 39.7+/-2.5, P<0.01). However, the expression of orexinIR neurons in the lateral hypothalamic area (LHA) was decreased (27.8+/-2.6 vs 20.6+/-1.7, P<0.01). B) The expression of c-Fos positive neurons was increased in the PVN and SON with IGS. A coexistence of oxytocin-IR positive neurons and c-Fos-IR ones in the PVN and SON from the adjacent brain sections was observed, confirming the activation of OT-containing neurons in the PVN and SON following IGS. CONCLUSION: IGS increases the expression of hypothalamic neurons containing the anorexigenic neuropeptide, oxytocin, and decreases the expression of neurons containing the orexigenic neuropeptide, orexin. This central anorexigenic effect of GES may contribute to the reduced appetite and increased satiety in obese patients with IGS therapy.

Animals↗

PubMed2005

Gastric electrical stimulation inhibits postprandial antral tone partially via nitrergic pathway in conscious dogs.

Gastric electrical stimulation (GES) has recently been explored as a therapeutic option for gastrointestinal motility disorders or obesity. The mechanism behind it is not fully elucidated. The aims of this study were to assess the effects of GES with different parameters on antral tone and to explore the involvement of the nitrergic pathway. Eight dogs equipped with a gastric cannula and one pair of serosal electrodes in the greater curvature 4 cm above the pylorus were studied on separate days. The study was composed of seven randomized sessions in the fed state [control, GES with different parameters, and GES plus neuronal nitric oxide synthase (nNOS) inhibitor]. Each session included three consecutive 30-min periods (baseline, GES, and recovery). GES was performed with long pulses or pulse trains. The antral volume was measured using an intragastric balloon connected with a barostat device. Behaviors of the dogs during each stimulation period were also noted. We found that 1) postprandial antral tone was reduced with GES with all tested parameter settings, reflected as a significant and substantial increase in antral volume ranging from 179 to 309%; 2) the inhibitory effect of GES on antral tone was partially blocked (decreased by 39.5%) with an nNOS inhibitor; and 3) mild symptoms were induced with GES and found to be correlated with the GES-induced increase in antral volume. We conclude that retrograde GES with long pulses or pulse trains inhibits antral tone, and this inhibitory effect is partially mediated via the nitrergic pathway. These results suggest that retrograde GES may have a therapeutic potential for obesity.

Animals↗