Crystallization Kinetics of Perovskite Films by a Green Mixture Antisolvent for Efficient NiOx-Based Inverted Solar Cells.

Environment-friendly antisolvents are critical for obtaining highly efficient, reproducible, and sustainable perovskite solar cells (PSCs). Here, we introduced a green mixture antisolvent of ethyl acetate-isopropanol (EA/IPA) to finely regulate the crystal grain growth and related film properties, including the morphology, crystal structure, and chemical composition of the perovskite thin film. The IPA with suitable content in EA plays a key role in achieving a smooth and compact high-quality perovskite thin film, leading to the suppression of film defect-induced nonradiative recombination. As a result, the PSCs based on the EA/IPA (5:1) antisolvent showed a power conversion efficiency of 22.9% with an open-circuit voltage of 1.17 V.

Investigation of the driving voltage on the high performance flexible ATF-ECDs based on PET/ITO/NiOX/LiTaO3/WO3/ITO.

High performance flexible all-thin-film electrochromic devices (ATF-ECDs) have been fabricated and systematically investigated by operating with different driving voltages during the electrochromic processes. The device structure (cross-section) and material properties of some main functional layers were presented and analysed. The electrochromic properties including kinetic and spectral tests were systematically investigated through combining chronoamperometry, cyclic voltammetry measurements and optical measurements. In addition, the open circuit memory measurement was also carried out. A much higher driving voltage might lead to a current leakage inside the device during coloring process. A proper driving voltage is needed for achieving high device performances. More details were widely described and deeply discussed.

Intestinal Electrical Stimulation Synchronized With Intestinal Slow Wave Ameliorates Glucagon-Induced Hyperglycemia in Rats.

BACKGROUND: Synchronized intestinal electrical stimulation (SIES), in which intestinal electrical stimulation (IES) is delivered in synchronization with the intrinsic slow wave of small intestine, was previously reported to be more potent in accelerating small intestine transit than IES delivered at fixed frequency and phase. We hypothesized that SIES is more potent in suppressing postprandial blood glucose by enhancing the release of glucagon-like peptide-1 (GLP-1) and insulin. MATERIALS AND METHODS: Rats underwent long-term implant of two pairs of electrodes at the duodenum for IES and SIES, respectively. Acute hyperglycemia was induced with glucagon, and the oral glucose tolerance test was performed on separate days with IES, SIES, or sham (no stimulation). RESULTS: 1. Glucagon reduced the percentage of normal slow wave in sham (70.9% ± 4.1%) from (84.9% ± 2.6%, p = 0.006) of control, which was ameliorated by SIES (82.5% ± 3.3%, p = 0.031). 2. IES and SIES reduced glucagon-induced increase of blood glucose (192 mg/dl) at 30 minutes by 17% and 20%, respectively. SIES showed a further inhibitory effect at 60 minutes (147 vs 171 mg/dl, p = 0.003, vs sham). 3. Compared with sham (139 pg/ml), GLP-1 at 30 minutes was increased in both IES (158 pg/ml) and SIES (169 pg/ml). GLP-1 level was still high at 60 minutes in rats with SIES. 4. At 30 minutes, the plasma insulin level was increased by 18.8 µIU/ml with SIES, which was significantly higher than that with sham (7.1 µIU/ml, p < 0.001) and IES (13.2 µIU/ml, p = 0.041). CONCLUSION: SIES is more effective than IES in reducing glucagon-induced acute hyperglycemia by enhancing the release of GLP-1 and insulin.

Application of optimized LSTM in prediction of the cumulative confirmed cases of COVID-19.

This paper proposes an optimized Long Short-Term Memory (LSTM+) model for predicting cumulative confirmed cases of COVID-19 in Germany, the UK, Italy, and Japan. The LSTM+ model incorporates two key optimizations: (1) fine-adjustment of parameters and (2) a 're-prediction' process that utilizes the latest prediction results from the previous iteration. The performance of the LSTM+ model is evaluated and compared with that of Backpropagation (BP) and traditional LSTM models. The results demonstrate that the LSTM+ model significantly outperforms both BP and LSTM models, achieving a Mean Absolute Percentage Error (MAPE) of less than 0.6%. Additionally, two illustrative examples employing the LSTM+ model further validate its general applicability and practical performance for predicting cumulative confirmed COVID-19 cases.

Damage Evolution of Polypropylene-Basalt Hybrid Fiber Ceramsite Concrete under Chloride Erosion and Dry-Wet Cycle.

To investigate the influence of polypropylene-basalt hybrid fibers (PBHFCC) on the durability of ceramsite concrete, this study determined the appearance change, mass loss rate, relative dynamic elastic modulus, compressive strength and splitting tensile strength of ceramsite concrete with four kinds of hybrid fibers volume admixture under chloride erosion and dry-wet cycles. The results reveal that under this effect, the apparent damage of each group of specimens increased with the growth of the erosion time. The quality, compressive strength and splitting tensile strength of the specimens all increased gradually during the erosion age period of the first 72 d and gradually decreased after 72 d. The relative dynamic elastic modulus was similarly mutated in 48 d. When the hybrid fiber content of the specimens is 0.15 vol %, the enhancement effect of ceramsite concrete is better than that of the other three amounts. The relative dynamic elastic modulus value is used as a damage variable to establish the damage equation, and the damage evolution equation of PBHFCC considering the volume of hybrid fiber under chloride erosion and dry-wet cycle is derived. The conclusions can be used as a reference for the durability design and construction of PBHFCC.

An efficient online peak detection algorithm for synchronized intestinal electrical stimulation and its application for treating diabetes.

Obesity is one of leading risk factors for type 2 diabetes and other types of chronic diseases. Synchronized intestinal electrical stimulation (SIES) has been explored for treating obesity and diabetes. In SIES, electrical stimulation is delivered to the small intestine in synchronization with the intrinsic intestinal myoelectrical activity (its basic rhythm is called slow wave) and therefore, the accurate detection of intestinal slow waves is critically important for SIES. The aim of this study is to detect the peaks in intestinal slow waves in real-time based on the automatic multiscale peak detection (AMPD) method. In this paper, we introduce an efficient technique for real-time detection of peaks in intestinal slow waves. The presented method is based on peak estimation of a given quasi-periodic signal using the AMPD method. This method uses a multi-scale approach to identify the peaks of the intestinal slow waves with high detection accuracy and a minimal delay. Throughout the experiments, the multi-scale technique is used to estimate the quasi-periodic signals using different signal-to-noise ratio, λ (optimal scale), and the "lag" ß (number of datapoints for right hand estimation) as important performance factors. The performance of the presented method is also calculated and utilized in the comparison process for 10 datasets of the intestinal slow waves from rats at λ = 150 ms and two values of ß = 100 ms and 150 ms. The experimental results show that the presented method has good overall accuracy for online peak detection while maintaining low memory and computational complexity. Numerically, the overall accuracy is above 90%, and 98% for the rodent intestinal slow waves at a time-lag of 150 ms. The developed SIES system has been applied to successfully reduce postprandial blood glucose in a rodent model of hyperglycemia. In conclusion, the developed algorithm is adequate for on-line peak detection of the intestinal slow waves; the SIES method used the developed peak detection algorithm which is effective in reducing postprandial blood glucose in a rodent model of hyperglycemia.

Dynamics of the water environment in a water quantity-quality-soil model of China's Yellow River basin: imbalance and driving factors.

Dynamic assessment of the water environment reflects variations in water resources in a basin under the combined influence of nature and humans and is a prerequisite for rational water management. This study provides an integrated assessment of the water environment in a water quantity-quality-soil model. Using the long-term monthly data from hydrological monitoring stations, the water environment of the Yellow River basin is assessed from the year 2006 to 2019. The kernel density estimation and the Dagum Gini coefficient are used to analyze the spatial and temporal imbalances of the water environment. Geographic detectors are used to extract external driving factors of the unbalanced evolution. The study results reveal that (1) the water environment in the basin shows a fluctuating downward trend, which mainly depends on the organic pollution control indicators, with a contribution of 22.85%. Scores of the water environment in the midstream are lower than those in the upstream and downstream due to the heavy pollutant discharges. (2) The spatial imbalance shows a fluctuating downward trend. Inter-regional variation is the primary source of regional variation in the water environment, with an average contribution of 56.02%. (3) The temporal imbalance of the water environment is on the rise, with a degree of multipolarity. The significant left trailing feature of the kernel density curve suggests that there are areas within the basin where the water environment is extremely poor. (4) For the overall basin and upstream, economic development and technological innovation are the main external driving factors influencing the spatial and temporal imbalances of the water environment. For the midstream and downstream, population density and environmental regulations are the main drivers. The interaction of any two factors has a greater impact than the single one.

The upregulation of circFNDC3B aggravates the recurrence after endoscopic submucosal dissection (ESD) in early gastric cancer (EGC) patients.

It has been reported that the expression of CD44 variant 9 could be utilized as a predictive marker for the recurrence in early gastric cancer (EGC) after endoscopic submucosal dissection (ESD). And circFNDC3B was proved to increase the migration and invasion of gastric cancer (GC) cells. In this study, we recruited 96 EGC patients after ESD treatment and grouped them into High circFNDC3B expression group (High expression group) and Low circFNDC3B expression group (Low expression group). Accordingly, we found that the recurrence-free rate in the High expression group was lower than that in the Low expression group. In the High expression group, the relative expression of miR-942 and miR-510 was both suppressed while the relative expression of CDH1 mRNA and CD44 mRNA/protein was increased compared with those in the Low expression group. CircFNDC3B was found to target miR-942 and miR-510 and suppress their expressions respectively. Moreover, miR-942 was found to target CD44 mRNA while miR-510 was found to target CDH1 mRNA. The overexpression of circFNDC3B led to the down-regulation of miR-942 and miR-510, which accordingly resulted in the up-regulation of CD44 and CDH1 in MKN28 cells. Moreover, we found H. pylori infection could promote the expression of circFNDC3B, which also resulted in up-regulated CD44 and CDH1 mRNA level in rTip-α cultivated MKN28 cells. In summary, our study demonstrated that a higher level of circFNDC3B could lead to the increased expression of CD44 and CDH1 via modulating the signaling pathways of miR-942/CD44 and miR-510/CDH1 in EGC patients. And the up-regulation of CD44 and CDH1 would accordingly result in a higher recurrence rate of EGC patients treated by ESD.

Defect Control for 12.5% Efficiency Cu2 ZnSnSe4 Kesterite Thin-Film Solar Cells by Engineering of Local Chemical Environment.

Kesterite-based Cu2 ZnSn(S,Se)4 semiconductors are emerging as promising materials for low-cost, environment-benign, and high-efficiency thin-film photovoltaics. However, the current state-of-the-art Cu2 ZnSn(S,Se)4 devices suffer from cation-disordering defects and defect clusters, which generally result in severe potential fluctuation, low minority carrier lifetime, and ultimately unsatisfactory performance. Herein, critical growth conditions are reported for obtaining high-quality Cu2 ZnSnSe4 absorber layers with the formation of detrimental intrinsic defects largely suppressed. By controlling the oxidation states of cations and modifying the local chemical composition, the local chemical environment is essentially modified during the synthesis of kesterite phase, thereby effectively suppressing detrimental intrinsic defects and activating desirable shallow acceptor Cu vacancies. Consequently, a confirmed 12.5% efficiency is demonstrated with a high VOC of 491 mV, which is the new record efficiency of pure-selenide Cu2 ZnSnSe4 cells with lowest VOC deficit in the kesterite family by Eg /q-Voc. These encouraging results demonstrate an essential route to overcome the long-standing challenge of defect control in kesterite semiconductors, which may also be generally applicable to other multinary compound semiconductors.

Efficient and Stable Planar n-i-p Sb2Se3 Solar Cells Enabled by Oriented 1D Trigonal Selenium Structures.

Environmentally benign and potentially cost-effective Sb2Se3 solar cells have drawn much attention by continuously achieving new efficiency records. This article reports a compatible strategy to enhance the efficiency of planar n-i-p Sb2Se3 solar cells through Sb2Se3 surface modification and an architecture with oriented 1D van der Waals material, trigonal selenium (t-Se). A seed layer assisted successive close spaced sublimation (CSS) is developed to fabricate highly crystalline Sb2Se3 absorbers. It is found that the Sb2Se3 absorber exhibits a Se-deficient surface and negative surface band bending. Reactive Se is innovatively introduced to compensate the surface Se deficiency and form an (101) oriented 1D t-Se interlayer. The p-type t-Se layer promotes a favored band alignment and band bending at the Sb2Se3/t-Se interface, and functionally works as a surface passivation and hole transport material, which significantly suppresses interface recombination and enhances carrier extraction efficiency. An efficiency of 7.45% is obtained in a planar Sb2Se3 solar cell in superstrate n-i-p configuration, which is the highest efficiency for planar Sb2Se3 solar cells prepared by CSS. The all-inorganic Sb2Se3 solar cell with t-Se shows superb stability, retaining ≈98% of the initial efficiency after 40 days storage in open air without encapsulation.

Back Contact Interfacial Modification in Highly-Efficient All-Inorganic Planar n-i-p Sb2Se3 Solar Cells.

Sb2Se3 is an emerging and promising light-absorbing material with superior photovoltaic properties. However, the specific one-dimensional structure of Sb2Se3 limits the doping density, preventing a high built-in potential. Moreover, in the superstrate devices the back contact is often non-ohmic. In this work, we have successfully applied tungsten oxide (WO3-x) as a hole-transport layer in superstrate n-i-p Sb2Se3 solar cells. It is found that an interfacial dipole is formed at Sb2Se3/WO3-x interface via Sb-W bonds, which reduces the barrier for hole extraction. Meantime, gap states are present at a suitable energy level to serve as intermediate states for hole-transport from the Sb2Se3 absorber to the metal anode. In addition, the introduction of WO3-x can suppress carrier recombination at the back interface, enhance the built-in potential, and improve the spectral response in the long-wavelength region. Consequently, the superstrate devices with the incorporated WO3-x layer achieve a champion efficiency of 7.10% due to the enhancement of all device parameters. Furthermore, the all-inorganic devices with WO3-x hole-transport layer exhibit excellent air stability and thermal stability.

SCFAs induce autophagy in intestinal epithelial cells and relieve colitis by stabilizing HIF-1α.

Hypoxia-inducible factor-1α (HIF-1α) is a critical regulator of barrier integrity during colonic mucosal injury. Previous works have shown that the absence of autophagy is implicated in the development of inflammatory bowel disease (IBD). Additionally, changes in bacterial profiles in the gut are intimately associated with IBD. Although HIF-1α, autophagy, microbiota, and their metabolites are all involved in the pathogenesis of IBD, their roles are not known. In this study, we investigated the relationship between HIF-1α and autophagy in healthy and inflammatory states using transgenic mice, colitis models, and cell culture models. We confirmed that the absence of intestinal epithelial HIF-1α changed the composition of the intestinal microbes and increased the susceptibility of mice to dextran sodium sulfate (DSS)-induced colitis. In addition, autophagy levels in the intestinal epithelial cells (IECs) were significantly reduced in IEC-specific HIF-1α-deficient (HIF-1α∆IEC) mice. Moreover, in the cell culture models, butyrate treatment significantly increased autophagy in HT29 cells under normal conditions, whereas butyrate had little effect on autophagy after HIF-1α ablation. Furthermore, in the DSS-induced colitis model, butyrate administration relieved the colonic injury and suppressed inflammation in Cre-/HIF-1α- (HIF-1αloxP/loxP) mice. However, the butyrate-mediated protection against colonic injury was considerably diminished in the HIF-1α∆IEC mice. These results show that HIF-1α, autophagy, and intestinal microbes are essential for the maintenance of intestinal homeostasis. Butyrate can alleviate DSS-induced colitis by regulating autophagy via HIF-1α. These insights may have important implications for the development of therapeutic strategies for IBD. KEY MESSAGES: • The absence of intestinal epithelial HIF-1α leads to downregulation of autophagy in mice. • The absence of intestinal epithelial HIF-1α exacerbates DSS-induced colitis. • Short-chain fatty acids (SCFAs) can alleviate DSS-induced colitis by regulating autophagy via HIF-1α.

Plasmonic Effects of Metallic Nanoparticles on Enhancing Performance of Perovskite Solar Cells.

We report systematic design and formation of plasmonic perovskite solar cells (PSCs) by integrating Au@TiO2 core-shell nanoparticles (NPs) into porous TiO2 and/or perovskite semiconductor capping layers. The plasmonic effects in the formed PSCs are examined. The most efficient configuration is obtained by incorporating Au@TiO2 NPs into both the porous TiO2 and the perovskite capping layers, which increases the power conversion efficiency (PCE) from 12.59% to 18.24%, demonstrating over 44% enhancement, compared with the reference device without the metal NPs. The PCE enhancement is mainly attributed to short-circuit current improvement. The plasmonic enhancement effects of Au@TiO2 core-shell nanosphere photovoltaic composites are explored based on the combination of UV-vis absorption spectroscopy, external quantum efficiency (EQE), photocurrent properties, and photoluminescence (PL). The addition of Au@TiO2 nanospheres increased the rate of exciton generation and the probability of exciton dissociation, enhancing charge separation/transfer, reducing the recombination rate, and facilitating carrier transport in the device. This study contributes to understanding of plasmonic effects in perovskite solar cells and also provides a promising approach for simultaneous photon energy and electron management.

Controllable Synthesis and Properties of Sb2Se3 Nanorods Synthesized by Hot-Injection Method.

Antimony selenide (Sb2Se3) is an interesting p-type semiconductor with a proper bandgap for photovoltaic devices. In this work, Sb2Se3 nanorods with controllable length-width ratios were synthesized via hot-injection method, where selenium powder was used as selenium sources and oleylamine was selected as reducing agent and high-point solvent. X-ray diffraction (XRD) patterns and high resolution Transmission electron microscope (HRTEM) results demonstrate that nanorods are wellcrystallized single crystalline and grow along the [110] direction. The reaction temperatures were found to have a noticeable influence on the morphologies of Sb2Se3 nanorods. The growth mechanism of the nanorods was discussed based on scanning electron microscope (SEM) observations. Vis-NIR absorption spectra reveal that the bandgaps of nanorods were between 0.75 eV and 1.1 eV. Electrical conductivities in dark and light were also investigated.

Gastric electrical stimulation optimized to inhibit gastric motility reduces food intake in dogs.

AIMS: 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. METHODS: 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. RESULTS: (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. CONCLUSION: 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.

Blunted Peripheral and Central Responses to Gastric Mechanical and Electrical Stimulations in Diet-induced Obese Rats.

BACKGROUND/AIMS: The increase in the prevalence of obesity is attributed to increased food intake and decreased physical activity in addition to genetic factors. Altered gut functions have been reported in obese subjects, whereas, little is known on the possible alterations in brain-gut interactions in obesity. The aim of the study was to explore possible alterations in gastric myoelectrical activity, gastric emptying, autonomic functions and central neuronal responses to gastric stimulations in diet-induced obese rats. METHODS: Gastric myoelectrical activity, gastric emptying and heart rate variability were recorded in lean and obese rats; extracellular neuronal activity in the ventromedial hypothalamus and its responses to gastric stimulations were also assessed. RESULTS: (1) Gastric emptying was significantly accelerated but gastric myoelectrical activity was not altered in obese rats; (2) the normal autonomic responses to feeding were absent in obese rats, suggesting an impairment of postprandial modulation of autonomic functions; and (3) central neuronal responses to gastric stimulations (both balloon distention and electrical stimulation) were blunted in obese rats, suggesting impairment in the brain-gut interaction. CONCLUSIONS: In diet-induced obese rats, gastric emptying is accelerated, postprandial modulations of autonomic functions is altered and central neuronal responses to gastric stimulations are attenuated. These alterations in peripheral, autonomic and brain-gut interactions may help better understand pathogenesis of obesity and develop novel therapeutic approaches for obesity.

Gastric electrical stimulation parameter dependently alters ventral medial hypothalamic activity and feeding in obese rats.

Gastric electrical stimulation (GES) has been used to treat obesity with unclear mechanisms and limited parameter ranges. This study explores effects of GES parameters on ventral medial hypothalamic (VMH) activity, feeding, and body weight in diet-induced obese (DIO) rats. For experiment 1, discharge rates were recorded in 39 gastric distension-responsive (GD-R) neurons in 12 DIO rats. Basal rates were compared with rates under GES using varied pulse amplitudes, widths, frequencies, and train-on times. For experiment 2, a crossover experiment in 16 DIO rats measured food intake and weight effects of GES pulse width, the parameter with the steepest neuronal response gradient in experiment 1. Treatments were sham and 0.5-, 2.0-, and 5.0-ms pulse GES. In experiment 1, 11 of 13 GES parameter sets tested produced significantly (P < 0.05) altered discharge rates of GD-R neurons. Increases in pulse amplitude (P < 0.05) and width (P < 0.0001) produced significant upward linear trends in response over the range tested, with the trend being strongest for pulse width. In experiment 2, over 4 days of 0.5-, 2.0-, and 5.0-ms GES treatment, food intake was 9.6% (P < 0.05), 21.0% (P < 0.0001), and 47.3% (P < 0.0001) lower than under sham-GES, whereas body weight changes were 0.7 (P = 0.48), 2.2 (P < 0.05), and 3.5 (P < 0.002) percentage points lower, respectively. We concluded that GES pulse width increases had the largest effect on VMH neuronal activity, and these effects were paralleled by pulse width-dependent reductions in food intake and body weight. Lengthening pulse width beyond the range used in prior clinical studies may be critical to making GES a viable obesity treatment.

Central neuronal mechanisms of intestinal electrical stimulation: effects on duodenum distention-responsive (DD-R) neurons in the VMH of rats.

Intestinal electrical stimulation (IES) has been shown to produce inhibitory effects on gastric contractions, gastric emptying, food intake and body weight in rats and dogs, suggesting a therapeutic potential for obesity. The aims of this study were (1) to test the hypothesis that the neurons in the VMH are involved in the central mechanisms of IES treatment for obesity; (2) to compare the effects of IES at the duodenum and IES at the ileum on neuronal activities of the VMH; (3) to better understand if the neuronal activity modulated by IES was mediated via the vagal pathway. Extracellular potentials of neurons in the VMH were recorded in 18 anesthetized rats. IES at the duodenum or ileum was performed in duodenal-distention responsive (DD-R) neurons with 3 sets of parameters (IES-1 with trains of short-pulses: 4mA, 2s-on, 3s-off, 2ms, 20Hz; IES-2 with long-pulses: 6mA, 20cpm, 100ms; IES-3, same as IES-1 but 40Hz). IES-1 at the duodenum and the ileum activated 70.6% and 73.3% of the DD-R neurons, respectively. Similar percentages of the neurons were activated with IES-3 at the duodenum and the ileum (70.6% vs. 66.7%, P=0.91), respectively. IES-2 at these locations activated only 25% and 46.2% of the DD-R neurons, respectively (P>0.05). IES at the duodenum with parameter set, IES-1 or IES-3 was significantly more potent than the parameter set, IES-2 (neuronal activation: 70.6% vs. 25%, P<0.05). Bilateral vagotomy only partially blocked the effects of IES on the neuronal activity in the VMH, indicating that extra-vagal pathways can mediate these effects. IES with different parameters activates 25-70.6% of the VMH neurons responsive to DD, and IES with trains of short-pulses seems more effective than IES with long-pulses. The vagal pathway and extra-vagal pathways are involved in the modulatory effects of IES on the central neurons in the satiety center.

Inhibitory effects and mechanisms of intestinal electrical stimulation on gastric tone, antral contractions, pyloric tone, and gastric emptying in dogs.

The aim of this study was to investigate the effects and mechanisms of intestinal electrical stimulation (IES) on gastric tone, antral and pyloric contractions, and gastric emptying in dogs. Female hound dogs were equipped with a duodenal or gastric cannula, and one pair of serosal electrodes was implanted in the small intestine. The study consisted of five different experiments. Liquid gastric emptying was assessed by collection of chyme from the duodenal cannula in a number of sessions with and without IES and with and without N-nitro-l-arginine (l-NNA). Postprandial antral and pyloric contractions were measured with and without IES and in the absence and presence of l-NNA or phentolamine by placement of a manometric catheter into the antrum and pylorus via the duodenal cannula. Gastric tone was assessed by measurement of gastric volume at a constant pressure. Gastric emptying was substantially and significantly delayed by IES or l-NNA compared with the control session. IES-induced delay of gastric emptying became normal with addition of l-NNA. IES reduced gastric tone, which was blocked by l-NNA. IES also inhibited antral contractions (frequency and amplitude), and this inhibitory effect was not blocked by l-NNA but was blocked by phentolamine. IES alone did not affect pyloric tone or resistance, but IES + l-NNA decreased pyloric tone. In conclusion, IES reduces gastric tone via the nitrergic pathway, inhibits antral contractions via the adrenergic pathway, does not affect pyloric tone, and delays liquid gastric emptying. IES-induced delay of gastric emptying is attributed to its inhibitory effects on gastric motility.

Therapeutic potential of synchronized gastric electrical stimulation for gastroparesis: enhanced gastric motility in dogs.

The aim of this study was to determine the effects and mechanism of synchronized gastric electrical stimulation (SGES) on gastric contractions and gastric emptying. The first experiment was designed to study the effects of SGES on antral contractions in four randomized sessions. Sessions 1 (control) and 2 (atropine) were performed in the fasting state, composed of three 30-min periods (baseline, stimulation, and recovery). Sessions 3 (control) and 4 (SGES performed during 2nd 20-min period) were performed in the fed state, consisting of two 20-min periods; glucagon was injected after the first 20-min recording. The second experiment was designed to study the effect of SGES on gastric emptying and consisted of two sessions (control and SGES). SGES was delivered with train duration of 0.5-0.8s, pulse frequency of 40 Hz, width of 2 ms, and amplitude of 4 mA. We found that 1) SGES induced gastric antral contractions in the fasting state. The motility index was 1.3 +/- 0.5 at baseline and 6.1 +/- 0.7 (P = 0.001) during SGES. This excitatory effect was completely blocked by atropine. 2) SGES enhanced postprandial antral contractions impaired by glucagon. 3) SGES significantly accelerated glucagon-induced delayed gastric emptying. Gastric emptying was 25.5 +/- 11.3% without SGES and 38.3 +/- 10.7% with SGES (P = 0.006 vs. control). This novel method of SGES induces gastric antral contractions in the fasting state, enhances glucagon-induced antral hypomotility in the fed state, and accelerates glucagon-induced delayed gastric emptying. The effect of SGES on antral contractions is mediated via the cholinergic pathway.