In vivo dynamic imaging of intestinal motions using diet-related autofluorescence

Background Tissue background autofluorescence induced by standard murine diets containing chlorophyll is a significant problem for fluorescence whole‐body imaging. However, as red chlorophyll autofluorescence delineates the gastrointestinal (GI) tract in the abdomen of the mouse, it should be possible to dynamically and non‐invasively image intestinal motions. Herein, we non‐invasively imaged for the first time intestinal motions, such as peristaltic and segmental motions, without an exogenous imaging agent, using red chlorophyll fluorescence. Methods Mice were illuminated with 660‐nm light from a laser diode and autofluorescence at 710 nm was acquired dynamically for 5 min with 200‐ms exposure time. Fluorescent imaging data were analyzed to generate a three‐dimensional spatiotemporal map to quantitate intestinal motions. Key Results Peristaltic and segmental motions were observed in vivo in mice. Our quantification showed that the frequency and propagation velocity of peristaltic contractile waves in the small intestine were measured to be 28.6 cycles per min and 1.82 ± 0.56 cm s^?1, respectively. Conclusions & Inferences This simple, but unexplored imaging technique can provide a means to monitor intestinal motility disorders and response to therapeutic agents.     

Inhibitory effects of bromelain,a cysteine protease derived from pineapple stem (Ananas comosus), on intestinal motility in mice

Background Bromelain (BR) is a cysteine protease with inhibitory effects on intestinal secretion and inflammation. However, its effects on intestinal motility are largely unexplored. Thus, we investigated the effect of this plant‐derived compound on intestinal contractility and transit in mice. Methods Contractility in vitro was evaluated by stimulating the mouse isolated ileum, in an organ bath, with acetylcholine, barium chloride, or electrical field stimulation. Motility in vivo was measured by evaluating the distribution of an orally administered fluorescent marker along the small intestine. Transit was also evaluated in pathophysiologic states induced by the pro‐inflammatory compound croton oil or by the diabetogenic agent streptozotocin. Key Results Bromelain inhibited the contractions induced by different spasmogenic compounds in the mouse ileum with similar potency. The antispasmodic effect was reduced or counteracted by the proteolytic enzyme inhibitor, gabexate (15 × 10^?6 mol L^?1), protease‐activated receptor‐2 (PAR‐2) antagonist, N¹‐3‐methylbutyryl‐N⁴‐6‐aminohexanoyl‐piperazine (10^?4mol L^?1), phospholipase C (PLC) inhibitor, neomycin (3 × 10^?3 mol L^?1), and phosphodiesterase 4 (PDE4) inhibitor, rolipram (10^?6 mol L^?1). In vivo, BR preferentially inhibited motility in pathophysiologic states in a PAR‐2‐antagonist‐sensitive manner. Conclusions & Inferences Our data suggest that BR inhibits intestinal motility – preferentially in pathophysiologic conditions – with a mechanism possibly involving membrane PAR‐2 and PLC and PDE4 as intracellular signals. Bromelain could be a lead compound for the development of new drugs, able to normalize the intestinal motility in inflammation and diabetes.     

Intracerebral,but not intravenous,transplantation of bone marrow stromal cells enhances functional recovery in rat cerebral infarct: An optical imaging study

Recent studies have indicated that bone marrow stromal cells (BMSC) may improve neurological function when transplanted into an animal model of CNS disorders, including cerebral infarct. However, there are few studies that evaluate the therapeutic benefits of intracerebral and intravenous BMSC transplantation for cerebral infarct. This study was aimed to clarify the favorable route of cell delivery for cerebral infarct in rats. The rats were subjected to permanent middle cerebral artery occlusion. The BMSC were labeled with near infrared (NIR)‐emitting quantum dots and were transplanted stereotactically (1 × 10⁶ cells) or intravenously (3 × 10⁶ cells) at 7 days after the insult. Using in vivo NIR fluorescence imaging technique, the behaviors of BMSC were serially visualized during 4 weeks after transplantation. Motor function was also assessed. Immunohistochemistry was performed to evaluate the fate of the engrafted BMSC. Intracerebral, but not intravenous, transplantation of BMSC significantly enhanced functional recovery. In vivo NIR fluorescence imaging could clearly visualize their migration toward the cerebral infarct during 4 weeks after transplantation in the intracerebral group, but not in the intravenous, group. The BMSC were widely distributed in the ischemic brain and some of them expressed neural cell markers in the intracerebral group, but not in the intravenous group. These findings strongly suggest that intravenous administration of BMSC has limited effectiveness at clinically relevant timing and intracerebral administration should be chosen for patients with ischemic stroke, although further studies would be warranted to establish the treatment protocol.     

Endoscopic Fluorescence Angiography with Indocyanine Green : A Preclinical Study in the Swine

ObjectiveMicroscopic indocyanine green (ICG) angiography is useful for identifying the completeness of aneurysm clipping and the preservation of parent arteries and small perforators. Neuroendoscopy is helpful for visualizing structures beyond the straight line of the microscopic view. We evaluated our prototype of endoscopic ICG fluorescence angiography in swine, which we developed in order to combine the merits of microscopic ICG angiography and endoscopy.MethodsOur endoscopic ICG system consists of a camera, a light source, a display and software. This system can simultaneously display real-time visible and near infrared fluorescence imaging on the same monitor. A commercially available endoscope was used, which was 4 mm in diameter and had an angle of 30°. A male crossbred swine was used.ResultsUnder general anesthesia, a small craniotomy was performed and the brain surface of the swine was exposed. ICG was injected via the ear vein with a bolus dose of 0.3 mg/kg. Visible and ICG fluorescence images of cortical vessels were simultaneously observed on the display monitor at high resolution. The real-time merging of the visible and fluorescent images corresponded well.ConclusionSimultaneous visible color and ICG fluorescent imaging of the cortical vessels in the swine brain was satisfactory. Technical improvement and clinical implication are expected.     

Cannabinoid 1 receptors modulate intestinal sensory and motor function in rat

Background Cannabinoid receptors are involved in visceral pain perception and control of intestinal motility in vivo. The underlying mechanisms are not well characterized. We aimed to determine whether the cannabinoid‐1 (CB₁) receptor modulates intestinal afferent nerve discharge and the peristaltic reflex. Methods Rats were anesthetized and intestinal segments were removed. Afferent nerve discharge from a mesenteric nerve was investigated in vitro in the presence of the CB₁ antagonist SR 141716A or the CB₁ agonist WIN 55212‐2. The myenteric peristaltic reflex was induced by electrical field stimulation and influence of SR 141716A or WIN 55212‐2 was recorded. Key Results Afferent nerve discharge to the algesic mediator bradykinin was reduced to 11 ± 5.1 imp s^?1 following pretreatment with SR 141716A and unchanged after WIN 55212‐2 compared to 63 ± 15.4 imp s^?1 in controls. At maximum distension pressure (80 cmH₂O) during ramp distension, 92 ± 12.4 imp s^?1 were reached following SR 141716A compared to 260 ± 13.2 in vehicle controls and 227 ± 15.4 in WIN 55212‐2 pretreated animals. In contrast, afferent discharge to 5‐HT (500 μmol L^?1) was increased to 75 ± 24.6 imp s^?1 following WIN 55212‐2 compared to 18 ± 5.9 imp s^?1 in controls, whereas SR 141716A had no effect. Ascending neuronal contractions were dose‐dependently attenuated in the presence of SR 141716A and latency of these contractions was reduced. WIN 55212‐2 had opposite effects that were abolished by SR 141716A. Conclusions & Inferences Activation of the CB₁ receptor differentially alters afferent intestinal nerve sensitivity to bradykinin, 5‐HT, and noxious mechanical distension, while it strengthens ascending neuronal contractions. Further studies are needed to determine the physiological relevance of these observations.     

Timing and cell dose determine therapeutic effects of bone marrow stromal cell transplantation in rat model of cerebral infarct

Stereotactic transplantation of bone marrow stromal cells (BMSCs) enables efficient delivery to the infarct brain. This study was aimed to assess its optimal timing and cell dose for ischemic stroke. The BMSCs were harvested from the green fluorescent protein‐transgenic rats and were labeled with quantum dots. The BMSCs (1 × 10⁵ or 1 × 10⁶) were stereotactically transplanted into the ipsilateral striatum of the rats subjected to permanent middle cerebral artery occlusion at 1 or 4 weeks post‐ischemia. Motor function was serially assessed. Using in vivo near infrared (NIR) fluorescence imaging, the engrafted BMSCs were visualized at 3 weeks post‐transplantation. Immunohistochemistry was performed to evaluate their fate. Functional recovery was significantly enhanced when both low and high doses of BMSCs were transplanted at 1 week post‐ischemia, but such therapeutic effects were observed only when the high‐dose BMSCs were transplanted at 4 weeks post‐ischemia. Both optical imaging and immunohistochemistry revealed their better engraftment in the peri‐infarct area when the high‐dose BMSCs were transplanted at 1 or 4 weeks post‐ischemia. These findings strongly suggest the importance of timing and cell dose to yield therapeutic effects of BMSC transplantation for ischemic stroke. Earlier transplantation requires a smaller number of donor cells for beneficial effects.     

Imaging of cerebrospinal fluid space and movement of hydrocephalus mice using near infrared fluorescence

Abstract We have studied optical imaging of mice cerebrospinal fluid (CSF) space and flow using near infrared (NIR) fluorescence. We applied our method to image CSF space and flow in a mice hydrocephalus model. Hydrocephalus was induced in mice with intracranial injections of transforming growth factor. Hydrocephalic and control mice were imaged using our NIR fluorescence imaging system. Hydrocephalic mice showed diminished intracranial CSF flow. Our system is sufficient to show altered CSF flow in a mouse hydrocephalus model. Optical imaging using near infrared is an effective modality to image CSF space and movement.     

The effects of methane and hydrogen gases produced by enteric bacteria on ileal motility and colonic transit time

Background Gases produced by intestinal flora may modulate intestinal motor function in healthy individuals as well as those with functional bowel disease. Methane, produced by enteric bacteria in the human gut, is associated with slowed intestinal transit and constipation. The effects of hydrogen, another main gas produced by bacterial fermentation in the gut, on small bowel and colonic motor function remains unrecognized. Therefore, we set out to investigate whether intestinal gases including methane and hydrogen could influence the small bowel motility and colonic transit. Methods Guinea pig ileum was placed in the peristaltic bath with tension transducers attached to measure velocity and amplitude of peristaltic contraction before and after the infusion of control, hydrogen, and methane gases. Also, changes in the intraluminal pressures were monitored before and after the gas infusions. Key Results Methane decreased peristaltic velocity and increased contraction amplitude significantly of guinea pig ileum (P < 0.05). The AUC of intraluminal pressure was significantly increased with methane in guinea pig ileum (P < 0.05). In a second experiment, guinea pig colon was placed in the peristaltic bath to measure transit time before and after control, hydrogen, methane, and methane‐hydrogen mixture gas infusions. Hydrogen shortened colonic transit time by 47% in the proximal colon, and by 10% in the distal colon, when compared with baselines (P < 0.05). Conclusions & Inferences Methane delayed ileal peristaltic conduction velocity by augmenting contractility. Hydrogen shortened colonic transit, and that effect was more prominent in the proximal colon than distal colon.     

MR Imaging of Slow Axonal Transport in Vivo

Three magnetopharmaceuticals based on a monocrystalline iron oxide nanocompound (MION) are evaluated as potential contrast agents for demonstrating axonal transport in vivo by magnetic resonance (MR) imaging. One agent has a strong positive charge, one has a strong negative charge, and the third is covalently linked to wheat germ agglutinin, a plant lectin with a high affinity for axon terminals. All three agents were tagged with rhodamine, and fluorescence microscopy was used to determine their fate after administration and to validate the imaging results. Following injection into or near various neural structures in the motor and visual systems of rats, MR images were obtained at multiple times up to 11 days later, and the imaged tissues were processed for subsequent histological examination. Similar results were obtained with all three agents. Axonal transport was not seen by MR imaging or fluorescence microscopy when the agents were injected into the calf muscles, the vitreous of the eye, or the superior colliculus. However, bidirectional axonal transport was shown unequivocally by both methods after injection directly into the site of a focal crush injury to the sciatic nerve. The nerve, which otherwise is isointense with surrounding tissues on MR images, appeared as a uniformly hypointense structure having a length approximately in proportion to the time from injection to imaging. By 11 days, the course of the nerve was traceable from its component roots in the cauda equina to its bifurcation into the tibial and common peroneal nerves in the leg. A transport rate of about 5 mm/day was calculated, which is consistent with the mechanism of slow transport. MION-based magnetopharmaceuticals thus can be used to demonstrate slow axonal transport, and thereby visualize peripheral nerves, in vivo by MR imaging.     

In vivo optical imaging correlates with improvement of cerebral ischemia treated by intravenous bone marrow stromal cells (BMSCs) and edaravone

Abstract

Objective:

Recent studies show that modern in vivo optical imaging can detect matrix metallopeptidase (MMP) activation in the ischemic brain. In this study, we analyze the protective effects of bone marrow stromal cells (BMSCs) and edaravone (EDA) against tissue plasminogen activator (tPA) risk in the ischemic brain with in vivo optical fluorescence MMP imaging.

Methods:

At 48 hours after 60 minutes of transient middle cerebral artery occlusion (tMCAO) with tPA, C57BL/6J mice were subjected to motor function analysis, in vivo and ex vivo optical imaging for MMP activation, gelatin zymography, and double immunofluorescent analyses with or without intravenous BMSC transplantation and the intravenous free radical scavenger EDA.

Results:

In vivo fluorescent signals for MMP were detected over the heads of living mice 48 hours after tMCAO; the strongest were in the tPA group, which were reduced by BMSC or EDA treatment. These in vivo data were confirmed by ex vivo fluorescence imaging. While massive intracerebral hemorrhages were observed in the ischemic hemispheres of the tPA group, only slight hemorrhages were found in the tPA/BMSC, tPA/EDA, and EDA groups. Gelatin zymography showed the strongest MMP-9 activation in the tPA group after tMCAO, which was reduced by BMSC or EDA treatment.

Conclusion:

The present study provides a correlation between in vivo optical imaging of MMP activation and the improvement of ischemic brain damage caused by tPA after tMCAO and treated by BMSC and EDA.     

Time lapse in vivo microscopy reveals distinct dynamics of microglia‐tumor environment interactions—a new role for the tumor perivascular space as highway for trafficking microglia

Microglial cells are critical for glioma growth and progression. However, only little is known about intratumoral microglial behavior and the dynamic interaction with the tumor. Currently the scarce understanding of microglial appearance in malignant gliomas merely originates from histological studies and in vitro investigations. In order to understand the pattern of microglia activity, motility and migration we designed an intravital study in an orthotopic murine glioma model using CX3CR1‐eGFP^GFP/wt mice. We analysed the dynamics of intratumoral microglia accumulation and activity, as well as microglia/tumor blood vessel interaction by epi‐illumination and 2‐photon laser scanning microscopy. We further investigated cellular and tissue function, including the enzyme activity of intratumoral and microglial NADPH oxidase measured by in vivo fluorescence lifetime imaging. We identified three morphological phenotypes of tumor‐associated microglia cells with entirely different motility patterns. We found that NADPH oxidase activation is highly divergent in these microglia subtypes leading to different production levels of reactive oxygen species (ROS). We observed that microglia motility is highest within the perivascular niche, suggesting relevance of microglia/tumor blood vessel interactions. In line, reduction of tumor blood vessels by antivascular therapy confirmed the relevance of the tumor vessel compartment on microglia biology in brain tumors. In summary, we provide new insights into in vivo microglial behavior, regarding both morphology and function, in malignant gliomas. GLIA 2016;64:1210–1226     

Impaired propulsive motility in the distal but not proximal colon of BK channel β1‐subunit knockout mice

Background Large‐conductance Ca²⁺‐activated K⁺ (BK) channels regulate smooth muscle tone. The BK channel β1‐subunit increases Ca²⁺ sensitivity of the α‐subunit in smooth muscle. We studied β1‐subunit knockout (KO) mice to determine if gastrointestinal (GI) motility was altered. Methods Colonic and intestinal longitudinal muscle reactivity to bethanechol and colonic migrating motor complexes (CMMCs) were measured in vitro. Gastric emptying and small intestinal transit were measured in vivo. Colonic motility was assessed in vivo by measuring fecal output and glass bead expulsion time. Myoelectric activity of distal colon smooth muscle was measured in vitro using intracellular microelectrodes. Key Results Bethanechol‐induced contractions were larger in the distal colon of β1‐subunit KO compared to wild type (WT) mice; there were no differences in bethanechol reactivity in the duodenum, ileum, or proximal colon of WT vsβ1‐subunit KO mice. There were more retrogradely propagated CMMCs in the distal colon of β1‐subunit KO compared to WT mice. Gastrointestinal transit was unaffected by β1‐subunit KO. Fecal output was decreased and glass bead expulsion times were increased in β1‐subunit KO mice. Membrane potential of distal colon smooth muscle cells from β1‐subunit KO mice was depolarized with higher action potential frequency compared to WT mice. Paxilline (BK channel blocker) depolarized smooth muscle cells and increased action potential frequency in WT distal colon. Conclusions & Inferences BK channels play a prominent role in smooth muscle function only in the distal colon of mice. Defects in smooth muscle BK channel function disrupt colonic motility causing constipation.     

Real‐time visualization of altered gastric motility by magnetic resonance imaging in patients with Parkinson's disease

Gastrointestinal motility is frequently affected in Parkinson's disease (PD) and has even been reported in early stages of PD. We hypothesized that gastric motility can be assessed in vivo by real‐time magnetic resonance imaging (MRI), an established, noninvasive method. After an overnight fast and a standardized test meal, 10 patients with PD (six drug naïve, four treated) and 10 healthy volunteers underwent real‐time MRI scanning of the stomach. Gastric motility was quantified by calculating the gastric motility indices (GMI) from transversal oblique und sagittal oblique MRI scans. There was a trend toward a decreased gastric motility in patients with PD compared with healthy controls (Mann‐Whitney test, P 0.059). This difference in peristalsis was due to a significant reduction in the amplitude of peristaltic contractions (P 0.029) and not to a decelerated velocity of the peristaltic waves (P 0.97). Real‐time MRI allows direct visualization of gastric motility in PD. In this pilot study, a relatively high interindividual variability impaired accurate separation of our PD sample from healthy controls. The trend toward decreased gastric motility is in accordance with previous studies that investigated gastric motility in patients with PD using other methods. Our study provides first demonstration of a possible underlying mechanism for disturbed gastric motility in PD (reduced amplitude of contractions versus altered velocity of peristaltic waves). Further studies in drug‐naïve PD patients are required to determine the discriminatory power and validity of this technique in PD. © 2010 Movement Disorder Society     

Identification of a Novel Indoline Derivative for in Vivo Fluorescent Imaging of Blood-Brain Barrier Disruption in Animal Models

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A novel method for the evaluation of intestinal transit and contractility in mice using fluorescence imaging and spatiotemporal motility mapping

Abstract  This study introduces a novel, simplified method for the evaluation of murine intestinal transit and contractility using fluorescence and video imaging. Intestinal transit was measured by evaluating the intestinal distribution of non-absorbable fluorescein-labelled dextran (70 kDa, FD70) along the gastrointestinal (GI) tract. After excision of the GI tract, two full-field images – one in normal illumination mode and another in fluorescent mode – were taken with a charge coupled device (CCD) camera and subsequently matched for calculation of fluorescence distribution along the GI tract. Immediately after, intestinal contractility was evaluated in different regions of the intact intestine by spatiotemporal motility mapping (i.e. video imaging). In control mice, the small intestine showed vigorous oscillatory contractions and FD70 was primarily distributed within the terminal ileum/caecum at 90 min postgavage. As validation step, the effect of intestinal manipulation (IM, surgical procedure) and two pharmacological agents – known to alter GI motility – was tested. At 24 h postoperatively, spontaneous contractile activity of the small intestine was nearly abolished in IM mice, leaving the small intestine distended and resulting in a significantly delayed intestinal transit. In accordance, spontaneous mechanical activity of circular muscle strips in standard organ baths was significantly reduced in IM mice compared to control mice. Administration of atropine (1–3 mg kg⁻¹, i.p.) suppressed spontaneous contractile activity along the entire intestinal tract and induced a dose-related delay in intestinal transit. In contrast, metoclopramide (3–10 mg kg⁻¹, i.p.) markedly increased contractile activity – however only in the upper GI tract – and accelerated intestinal transit in a dose-dependent manner.     

Differential effects of CB1 neutral antagonists and inverse agonists on gastrointestinal motility in mice

Background Cannabinoid type 1 (CB₁) receptors are involved in the regulation of gastrointestinal (GI) motility and secretion. Our aim was to characterize the roles of the CB₁ receptor on GI motility and secretion in vitro and in vivo by using different classes of CB₁ receptor antagonists. Methods Immunohistochemistry was used to examine the localization of CB₁ receptor in the mouse ileum and colon. Organ bath experiments on mouse ileum and in vivo motility testing comprising upper GI transit, colonic expulsion, and whole gut transit were performed to characterize the effects of the inverse agonist/antagonist AM251 and the neutral antagonist AM4113. As a marker of secretory function we measured short circuit current in vitro using Ussing chambers and stool fluid content in vivo in mouse colon. We also assessed colonic epithelial permeability in vitro using FITC‐labeled inulin. Key Results In vivo, the inverse agonist AM251 increased upper GI transit and whole gut transit, but it had no effect on colonic expulsion. By contrast, the neutral antagonist AM4113 increased upper GI transit, but unexpectedly reduced both colonic expulsion and whole gut transit at high, but not lower doses. Conclusions & Inferences Cannabinoid type 1 receptors regulate small intestinal and colonic motility, but not GI secretion under physiological conditions. Cannabinoid type 1 inverse agonists and CB₁ neutral antagonists have different effects on intestinal motility. The ability of the neutral antagonist not to affect whole gut transit may be important for the future development of CB₁ receptor antagonists as therapeutic agents.     

Full‐field optical coherence microscopy is a novel technique for imaging enteric ganglia in the gastrointestinal tract

Background Noninvasive methods are needed to improve the diagnosis of enteric neuropathies. Full‐field optical coherence microscopy (FFOCM) is a novel optical microscopy modality that can acquire 1 μm resolution images of tissue. The objective of this research was to demonstrate FFOCM imaging for the characterization of the enteric nervous system (ENS). Methods Normal mice and EdnrB^‐/‐ mice, a model of Hirschsprung’s disease (HD), were imaged in three‐dimensions ex vivo using FFOCM through the entire thickness and length of the gut. Quantitative analysis of myenteric ganglia was performed on FFOCM images obtained from whole‐mount tissues and compared with immunohistochemistry imaged by confocal microscopy. Key Results Full‐field optical coherence microscopy enabled visualization of the full thickness gut wall from serosa to mucosa. Images of the myenteric plexus were successfully acquired from the stomach, duodenum, colon, and rectum. Quantification of ganglionic neuronal counts on FFOCM images revealed strong interobserver agreement and identical values to those obtained by immunofluorescence microscopy. In EdnrB^‐/‐ mice, FFOCM analysis revealed a significant decrease in ganglia density along the colorectum and a significantly lower density of ganglia in all colorectal segments compared with normal mice. Conclusions & Inferences Full‐field optical coherence microscopy enables optical microscopic imaging of the ENS within the bowel wall along the entire intestine. FFOCM is able to differentiate ganglionic from aganglionic colon in a mouse model of HD, and can provide quantitative assessment of ganglionic density. With further refinements that enable bowel wall imaging in vivo, this technology has the potential to revolutionize the characterization of the ENS and the diagnosis of enteric neuropathies.     

12Effects of synchronized intestinal electrical stimulation on small intestinal motility in dogs

Our previous studies showed that synchronized gastric electrical stimulation enhanced antral contractions, accelerated gastric emptying in dogs. It has never been reported whether synchronized electrical stimulation could improve small intestinal motility. The aim of this study was to investigate the effects of synchronized intestinal electrical stimulation (SIES) on small bowel motility in both fasting and fed states in dogs. Methods: Five healthy female dogs (18–24 kg) were equipped with a duodenal cannula for the measurement of small bowel motility using manometry. Two pairs of bipolar electrodes were implanted on the small intestinal serosa with an interval of 25 cm; the first one was 10 cm beyond the pylorus and used for stimulation. The experiment was consisted of four sessions in each dog with a randomized order. In the fasting state, 20 min after occurrence of phase III, SIES was initiated and maintained for 45 min, small bowel motility was recorded during the entire experiment, and no stimulation was performed in the control session. In other two sessions, dogs were fed with solid meal at the beginning of the experiment; glucagon (0.1 mg kg^­1) was injected 20 min after feeding, SIES was initiated at the same time for 20 min followed by 20 min recovery period. The stimulus was composed of train of pulses with on‐time of 0.5 s, frequency of 20 Hz, pulse width of 2 ms and amplitude of 4 mA. Results: 1). In the fasting state, SIES induced small intestinal contractions during phase I. The motility index was 5.2 ± 0.6 in the control session and significantly increased to 10.3 ± 0.7 with SIES (P = 0.003). 2). In the fed state, glucagon substantially and significantly inhibited small intestinal motility. The motility index was 11.3 ± 0.7 after feeding and reduced to 3.4 ± 0.5 with glucagon injection (P < 0.001). SIES significantly enhanced glucagon‐induced small intestinal postprandial hypomotility. The motility index was 3.4 ± 0.5 in the control session and increased to 6.0 ± 0.3 with the presence of SIES (P = 0.03). Conclusions: Intestinal electrical stimulation synchronized with intestinal slow waves induces intestinal contractions during phase I and enhanced small intestinal postprandial hypomotility induced by glucagon. SIES may have the therapeutic potential for treating small intestinal motility disorders. (Supported by a grant from American Diabetes Association).     

Modulation of heme oxygenase/carbon monoxide system affects the inhibitory neurotransmission involved in gastrointestinal motility of streptozotocin‐treated diabetic rats

Abstract Alterations in gastrointestinal motility of diabetic patients have been linked to degenerative changes induced by glucose abnormalities in the peripheral nervous system. The heme oxygenase/carbon monoxide (HO/CO) signalling represents one of the non‐adrenergic/non‐cholinergic (NANC) neurotransmission pathways involved in regulation of physiological peristalsis. To investigate the role of HO/CO system in intestinal motility under diabetic conditions, the response to electrical field stimulation (EFS) and western blot analysis of HO/CO pathway components were studied on duodenum longitudinal smooth muscle strips isolated from streptozotocin (STZ)‐treated diabetic rats (65 mg kg^?1, i.p.) and respective controls (CTRL), 6 weeks after the onset of diabetes. When compared to CTRL, the ability of CO releasing molecule (CORM‐3) (100–400 μmol L^?1) to enhance NANC relaxation was significantly impaired in STZ‐treated rats (P < 0.05). Conversely, in vitro incubation with the HO inhibitor ZnPPIX (10 μmol L^?1, 60 min) significantly reduced EFS‐induced relaxation in CTRL (P < 0.05), but not in STZ‐treated rats. Interestingly, the ability of ZnPPIX to inhibit EFS‐induced relaxation was partially restored in STZ‐treated rats co‐administered in vivo with the HO‐1 inducer cobalt protoporphyrin IX (CoPPIX) (0.5 mg per 100 g body weight weekly). Expression of inducible HO‐1 protein was increased in homogenates from STZ‐treated rats (vs CTRL, P < 0.01), and further increased in STZ‐treated rats receiving CoPPIX (P < 0.05). Taken together, our data underline the essential role of HO/CO system in regulation of inhibitory NANC neurotransmission in the duodenum and suggest that dysregulation of HO/CO activity may represent one mechanism by which gastrointestinal motility is altered in diabetes.     

Development of surgical confocal scanning microscope for intra-operative imaging of brain tumors using near infrared fluorescence: Technicalnote

Abstract

We developed a confocal laser scanning microscope for intra-operative imaging of brain tumors using near infrared fluorescence. The quality of near infrared images of Indocyanine Green (ICG) was compared with the surgical confocal scanning (SCS) microscope and a conventional charge-coupled device (CCD) camera; we compared images of a tube filled with ICG, which was located in the mouse brain. Compared to the CCD camera, the SCS microscope could obtain a more precise image of ICG fluorescence through the brain tissue. In addition, the SCS microscope could image ICG fluorescence clearly in a relatively light room because of elimination of stray light, while the CCD camera required high darkness to obtain ICC images. The present SCS microscope can give useful intra-operative imaging of brain tumors, particularly detection of residual tumor tissues that extend into normal brain tissues. [Neurol Res 2000; 22: 533-536]