Building on existing tools to improve chronic disease prevention and screening in public health: a cluster randomized trial.

BACKGROUND: The BETTER (Building on Existing Tools to Improve Chronic Disease Prevention and Screening in Primary Care) intervention was designed to integrate the approach to chronic disease prevention and screening in primary care and demonstrated effective in a previous randomized trial. METHODS: We tested the effectiveness of the BETTER HEALTH intervention, a public health adaptation of BETTER, at improving participation in chronic disease prevention and screening actions for residents of low-income neighbourhoods in a cluster randomized trial, with ten low-income neighbourhoods in Durham Region Ontario randomized to immediate intervention vs. wait-list. The unit of analysis was the individual, and eligible participants were adults age 40-64 years residing in the neighbourhoods. Public health nurses trained as "prevention practitioners" held one prevention-focused visit with each participant. They provided participants with a tailored prevention prescription and supported them to set health-related goals. The primary outcome was a composite index: the number of evidence-based actions achieved at six months as a proportion of those for which participants were eligible at baseline. RESULTS: Of 126 participants (60 in immediate arm; 66 in wait-list arm), 125 were included in analyses (1 participant withdrew consent). In both arms, participants were eligible for a mean of 8.6 actions at baseline. At follow-up, participants in the immediate intervention arm met 64.5% of actions for which they were eligible versus 42.1% in the wait-list arm (rate ratio 1.53 [95% confidence interval 1.22-1.84]). CONCLUSION: Public health nurses using the BETTER HEALTH intervention led to a higher proportion of identified evidence-based prevention and screening actions achieved at six months for people living with socioeconomic disadvantage. TRIAL REGISTRATION: NCT03052959 , registered February 10, 2017.

Cost-effectiveness of duloxetine for knee OA subjects: the role of pain severity.

OBJECTIVE: Establish the impact of pain severity on the cost-effectiveness of generic duloxetine for knee osteoarthritis (OA) in the United States. DESIGN: We used a validated computer simulation of knee OA to compare usual care (UC) - intra-articular injections, opioids, and total knee replacement (TKR) - to UC preceded by duloxetine in those no longer achieving pain relief from non-steroidal anti-inflammatory drugs (NSAIDs). Outcomes included quality-adjusted life years (QALYs), lifetime medical costs, and incremental cost-effectiveness ratios (ICERs). We considered cohorts with mean ages 57-75 years and Western Ontario and McMaster Osteoarthritis Index (WOMAC) pain 25-55 (0-100, 100-worst). We derived inputs from published data. We discounted costs and benefits 3% annually. We conducted sensitivity analyses of duloxetine efficacy, duration of pain relief, toxicity, and costs. RESULTS: Among younger subjects with severe pain (WOMAC pain = 55), duloxetine led to an additional 9.6 QALYs per 1,000 subjects (ICER = $88,500/QALY). The likelihood of duloxetine being cost-effective at willingness-to-pay (WTP) thresholds of $50,000/QALY and $100,000/QALY was 40% and 54%. Offering duloxetine to older patients with severe pain led to ICERs >$150,000/QALY. Offering duloxetine to subjects with moderate pain (pain = 25) led to ICERs <$50,000/QALY, regardless of age. Among knee OA subjects with severe pain (pain = 55) who are unwilling or unable to undergo TKR, ICERs were <$50,600/QALY, regardless of age. CONCLUSIONS: Duloxetine is a cost-effective addition to knee OA UC for subjects with moderate pain or those with severe pain unable or unwilling to undergo TKR. Among younger subjects with severe pain, duloxetine is cost-effective at WTP thresholds >$88,500/QALY.

Surgical outcomes and the impact of major surgery on quality of life, activity impairment and sexual health in hidradenitis suppurativa patients: a prospective single centre study.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic debilitating skin disease, frequently located in the groin and anogenital area, leading to a substantial impact on quality of life and sexual health in patients with HS. Skin-tissue-sparing excision with electrosurgical peeling (STEEP) is a procedure with known low recurrence rates and high patient satisfaction in retrospective series. However, a prospective study to investigate the impact of any major surgery on specific aspects of the quality of life has not yet been performed. OBJECTIVE: To assess surgical outcomes and the effect of major surgery on the general quality of life, sexual health and activity impairment in patients with HS. MATERIALS AND METHODS: A single centre prospective survey study was conducted among 40 patients undergoing major surgery. Surveys were completed prior to the surgery and 2, 6, 12 and 26 weeks after surgery. Besides the objective parameters (time to wound closure and surface of the wound), patient-reported outcomes were reported. RESULTS: Thirty-nine patients with a total of 171 survey responses were included for analysis. Patients with Hurley stage I or II had a shorter time to wound closure (TTWC) compared to patients with Hurley stage III (P = 0.005). TTWC was significantly prolonged in patients treated with biologics (P < 0.001). Smoking did not significantly influence TTWC. For patient-reported outcomes, DLQI and ASEX scores did not significantly improve during the study period of 6 months. However, activity and overall work impairment showed considerable improvement after surgery. CONCLUSION: Time to wound closure is significantly prolonged by higher Hurley stage and treatment with biologics, contrastingly not by smoking. Major surgery improved the overall work and daily activity impairment.

Stimulus-induced pacemaker activity in interstitial cells of Cajal associated with the deep muscular plexus of the small intestine.

BACKGROUND: The ICC-DMP have been proposed to generate stimulus-dependent pacemaker activity, rhythmic transient depolarizations, that take part in orchestrating segmentation and clustered propulsive motor patterns in the small intestine. However, little is known about the fundamental properties of ICC-DMP. METHODS: This study was undertaken to increase our understanding of intrinsic properties of the ICC-DMP through calcium imaging and intracellular electrical recordings. KEY RESULTS: Without stimulation, most ICC-DMP were quiescent. In some preparations ICC-DMP generated rhythmic low-frequency calcium oscillations (<10 cpm) with or without high frequency activity superimposed (>35 cpm). Immunohistochemistry proved the existence of NK1R on the ICC-DMP and close contacts between ICC-DMP and substance P-positive nerves. Substance P (25 nM) induced low-frequency calcium oscillations that were synchronized across the ICC-DMP network. Substance P also induced low frequency rhythmic transient depolarizations (<10cpm) in circular muscle cells close to the ICC-DMP. An intracellular recording from a positively identified ICC-DMP showed rhythmic transient depolarizations with superimposed high frequency activity. To investigate if quiescent ICC-DMP were chronically inhibited by nitrergic activity, nNOS was inhibited, but without effect. CONCLUSIONS & INFERENCES: Substance P changes non-synchronized high frequency flickering or quiescence in ICC-DMP into strong rhythmic calcium transients that are synchronized within the network; they are associated with rhythmic transient depolarizations within the same frequency range. We hypothesize that Substance P, released from nerves, can evoke rhythmicity in ICC-DMP, thereby providing it with potential pacemaker activity.

Involvement of 5-HT3 and 5-HT4 receptors in colonic motor patterns in rats.

BACKGROUND: Colonic migrating motor complexes in the rat constitute two distinct propulsive motor patterns, pan-colonic rhythmic long distance contractions (LDCs), and rhythmic propulsive motor complexes (RPMCs) occurring primarily in the mid/distal colon. Interstitial cells of Cajal govern their rhythmicity, but their occurrence is dependent on neural programs. Our aim was to investigate the involvement of 5-HT3 and 5-HT4 receptors in the generation and pharmacological control of the motor patterns. METHODS: Effects of 5-HT-related drugs on colonic motor patterns were analyzed through spatio-temporal maps created from video recordings of whole organ motility. KEY RESULTS: 5-HT3 antagonists abolished RPMCs and LDCs. 5-HT4 agonists inhibited LDCs; they promoted RPMCs, which was blocked by the 5-HT4 antagonist GR 125487. 5-HT and the 5-HT3 agonist m-CPBG strongly inhibited LDCs and RPMCs. CONCLUSIONS & INFERENCES: The generation of LDCs involves ongoing 5-HT release acting on 5-HT3 and 5-HT4 receptors. The spontaneous generation of RPMCs involves ongoing 5-HT release acting on 5-HT3 but not 5-HT4 receptors. Prucalopride and mosapride promote RPMCs, an effect that is inhibited by the 5-HT4 receptor antagonist GR 125487. A 5-HT3 agonist does not promote RPMCs. Segmentation, including a pattern of sequential segmental activity not previously described, can occur without significant involvement of 5-HT3 and 5-HT4 receptors. 5-HT and a 5-HT3 agonist are strongly inhibitory indicating that 5-HT receptors are present in inhibitory pathways which are normally not involved in the generation of spontaneous or distention-induced motor patterns.

Surgery under general anaesthesia in severe hidradenitis suppurativa: a study of 363 primary operations in 113 patients.

BACKGROUND: Treatment of hidradenitis suppurativa (HS) is a difficult undertaking, especially as there is no consensus on what surgical technique is preferred. At our centre severe HS (Hurley II/III) is operated under general anaesthesia, mostly with the STEEP procedure. OBJECTIVES: To investigate characteristics, surgical outcomes and patient satisfaction of HS patients who underwent deroofing or STEEP under general anaesthesia. METHODS: A clinical records-based retrospective analysis was conducted of all patients who had surgery under general anaesthesia between 1999 and 2013. Patient satisfaction was retrospectively investigated with questionnaires. RESULTS: A total of 482 operations (363 primary operations and 119 re-operations) were performed during the study period. The proportion of women in the included population was 68%. The median diagnostic delay (patient's and doctor's delay) was 6.5 years. Relapses occurred after 29.2% of primary operations. Women had higher relapse rates than men [odds ratio 2.85 (1.07;7.61)]. Hypergranulation of the wound was the most common complication and occurred in 7% of all operations. The median score patients attributed to the medical effect of surgery was eight of 10 (zero corresponding to very dissatisfied and 10 to very satisfied). CONCLUSION: The diagnostic delay in HS is long due to a lack of knowledge in both patients and health care professionals, indicating that there is a need for education. Deroofing and the STEEP are effective surgical procedures in severe cases of HS and lead to a relatively high patient satisfaction. The postoperative relapse risk is higher in women. Prospective studies are required for the development of clear guidelines on the appropriate choice of surgery.

Intestinal microbiota influence the early postnatal development of the enteric nervous system.

BACKGROUND: Normal gastrointestinal function depends on an intact and coordinated enteric nervous system (ENS). While the ENS is formed during fetal life, plasticity persists in the postnatal period during which the gastrointestinal tract is colonized by bacteria. We tested the hypothesis that colonization of the bowel by intestinal microbiota influences the postnatal development of the ENS. METHODS: The development of the ENS was studied in whole mount preparations of duodenum, jejunum, and ileum of specific pathogen-free (SPF), germ-free (GF), and altered Schaedler flora (ASF) NIH Swiss mice at postnatal day 3 (P3). The frequency and amplitude of circular muscle contractions were measured in intestinal segments using spatiotemporal mapping of video recorded spontaneous contractile activity with and without exposure to lidocaine and N-nitro-L-arginine (NOLA). KEY RESULTS: Immunolabeling with antibodies to PGP9.5 revealed significant abnormalities in the myenteric plexi of GF jejunum and ileum, but not duodenum, characterized by a decrease in nerve density, a decrease in the number of neurons per ganglion, and an increase in the proportion of myenteric nitrergic neurons. Frequency of amplitude of muscle contractions were significantly decreased in the jejunum and ileum of GF mice and were unaffected by exposure to lidocaine, while NOLA enhanced contractile frequency in the GF jejunum and ileum. CONCLUSIONS & INFERENCES: These findings suggest that early exposure to intestinal bacteria is essential for the postnatal development of the ENS in the mid to distal small intestine. Future studies are needed to investigate the mechanisms by which enteric microbiota interact with the developing ENS.

Bifidobacterium longum NCC3001 inhibits AH neuron excitability.

BACKGROUND: Bifidobacterium longum (B. longum) NCC3001 can affect behavior and brain biochemistry, but identification of the cellular targets needs further investigation. Our hypothesis was that the communication with the brain might start with action on enteric sensory neurons. METHODS: Ileal segments from adult mice were used to create a longitudinal muscle-myenteric-plexus preparation to expose sensory after-hyperpolarizing (AH) neurons in the myenteric plexus to allow access with microelectrodes. The intrinsic excitability of AH neurons was tested in response to the perfusion of conditioned media (B. longum culture supernatant) or unconditioned media (growth medium, MRS). KEY RESULTS: B. longum conditioned medium significantly reduced the excitability of AH neurons compared to perfusion with the unconditioned medium. Specifically, a reduction was seen in the number of action potentials fired per depolarizing test pulse, the instantaneous and time-dependent input resistances and the magnitude of the hyperpolarization-activated cationic current (Ih ). CONCLUSIONS & INFERENCES: The probiotic B. longum reduces excitability of AH sensory neurons likely via opening of potassium channels and closing of hyperpolarization-activated cation channels.

Test of normality for integrated change point detection and mixture modeling.

Single-molecule data often show step-like changes in the quantity measured between constant levels. Analysis of this data consists of detecting the steps, i.e., change point detection (CPD), and determining the levels, i.e., clustering. We describe a novel algorithm which integrates these two analyses, based on a statistical test of a normal distribution. The test of normality (TON) algorithm integrates statistical CPD with gaussian mixture model clustering. We used TON with both simulated data and ion channel patch-clamp recordings. It performed well with simulated data except at a high signal-to-noise ratio and when the frequency of steps was high compared to the sampling frequency. TON has advantages over separate CPD and mixture modeling algorithms, especially for complex single-molecule data. This was illustrated by its application to the maxichannel, an ion channel with multiple subconductance states.

Ca2+ sensitivity of the maxi chloride channel in interstitial cells of Cajal.

BACKGROUND: Interstitial cells of Cajal (ICC) associated with the myenteric plexus of the small intestine express maxi chloride channels. Our aim was to investigate whether or not these channels would be activated by increases in intracellular Ca(2+) , as that would strengthen evidence for their potential role in ICC pacemaking. A further aim was to examine whether inwardly and outwardly rectifying maxi chloride currents signify different channels. METHODS: We used Fluo-4 AM Ca(2+) imaging and patch clamp electrophysiology (cell-attached and inside-out) on isolated ICC in short term culture. KEY RESULTS: Increasing intracellular Ca(2+) by three functionally distinct mechanisms (blocking sarcoplasmic reticulum Ca(2+) refilling, creating membrane Ca(2+) pores and a solution designed to block plasmalemmal Ca(2+) extrusion) was followed by inwardly rectifying maxi chloride channel activation assessed in the cell-attached configuration. Furthermore, in the inside-out configuration, increased outwardly rectifying maxi-chloride channel activity followed an increase in Ca(2+) to 2 mmol L(-1) at the cytoplasmic face of the channel. CONCLUSIONS & INFERENCES: Increase in intracellular Ca(2+) will activate the maxi chloride channels. Maxi chloride currents are inwardly rectifying in the cell-attached patch clamp configuration under physiological conditions and are outwardly rectifying in the inside-out configuration. The same channel is responsible for both currents. Ca(2+) does not appear to regulate the rectification.

Low-dose rituximab is effective in pemphigus.

BACKGROUND: Rituximab, an anti-CD20 antibody, was shown in open series studies to be effective in treating pemphigus at a dose of 4 × 375 mgm(-2) as approved for B-cell malignancies. OBJECTIVES: We investigated whether a lower dose of rituximab is also effective for pemphigus. METHODS: Patients with pemphigus were treated with a single course of two infusions of rituximab (500 mg each) at an interval of 2 weeks. Clinical consensus late end points, B-cell number, desmoglein 1 and desmoglein 3 indices were monitored. RESULTS: We enrolled 15 patients in the study: three with pemphigus foliaceus (PF) and 12 with pemphigus vulgaris (PV). The follow-up was 32-152 weeks (median 94). All 15 patients responded to therapy. Eight patients achieved complete remission in a median period of 5 weeks (four on minimal therapy, four off therapy). Seven patients achieved partial remission in a median period of 34·5 weeks (five on minimal therapy, two off therapy). Relapses (40%) were seen between 53 and 103 weeks (median 97) after start of therapy. B-cell numbers dropped to <1% after first infusion, and remained undetectable in patients with sustained remission. The antidesmoglein 1 index correlated well with the clinical severity in PF, but this was less obvious in PV. CONCLUSIONS: A low dose of rituximab is an effective and safe treatment for pemphigus. Relapses may occur, mostly at the end of the second year. Cost-effectiveness studies with a long follow-up are required to determine the proper dosage of this expensive drug in pemphigus.

The anxiolytic effect of Bifidobacterium longum NCC3001 involves vagal pathways for gut-brain communication.

BACKGROUND: The probiotic Bifidobacterium longum NCC3001 normalizes anxiety-like behavior and hippocampal brain derived neurotrophic factor (BDNF) in mice with infectious colitis. Using a model of chemical colitis we test whether the anxiolytic effect of B. longum involves vagal integrity, and changes in neural cell function. Methods Mice received dextran sodium sulfate (DSS, 3%) in drinking water during three 1-week cycles. Bifidobacterium longum or placebo were gavaged daily during the last cycle. Some mice underwent subdiaphragmatic vagotomy. Behavior was assessed by step-down test, inflammation by myeloperoxidase (MPO) activity and histology. BDNF mRNA was measured in neuroblastoma SH-SY5Y cells after incubation with sera from B. longum- or placebo-treated mice. The effect of B. longum on myenteric neuron excitability was measured using intracellular microelectrodes. KEY RESULTS: Chronic colitis was associated with anxiety-like behavior, which was absent in previously vagotomized mice. B. longum normalized behavior but had no effect on MPO activity or histological scores. Its anxiolytic effect was absent in mice with established anxiety that were vagotomized before the third DSS cycle. B. longum metabolites did not affect BDNF mRNA expression in SH-SY5Y cells but decreased excitability of enteric neurons. CONCLUSIONS & INFERENCES: In this colitis model, anxiety-like behavior is vagally mediated. The anxiolytic effect of B. longum requires vagal integrity but does not involve gut immuno-modulation or production of BDNF by neuronal cells. As B. longum decreases excitability of enteric neurons, it may signal to the central nervous system by activating vagal pathways at the level of the enteric nervous system.

Role of interstitial cells of Cajal in the generation and modulation of motor activity induced by cholinergic neurotransmission in the stomach.

BACKGROUND: Interstitial cells of Cajal (ICC) are intimately linked to the enteric nervous system and a better understanding of the interactions between the two systems is going to advance our understanding of gut motor control. The objective of the present study was to investigate the role of ICC in the generation of gastric motor activity induced by cholinergic neurotransmission. METHODS: Gastric motor activity was evoked through activation of intrinsic cholinergic neural activity, in in vitro muscle strips by electrical field stimulation, in the in vitro whole stomach by distension and in vivo by fluoroscopy after gavaging the stomach with barium sulfate. The cholinergic activity was assessed as that component of the effect of the stimulus that was sensitive to atropine. These experiments were carried out in wild-type and Ws/Ws rats that have few intramuscular ICC (ICC-IM) in the stomach. KEY RESULTS: Under all three experimental conditions, cholinergic activity was prominent in both wild-type and W mutant rats providing evidence against the hypothesis that cholinergic neurotransmission to smooth muscle is primarily mediated by ICC-IM. Strong cholinergic activity in Ws/Ws rats was not due to upregulation of muscarinic receptors in ICC but possibly in smooth muscle of the antrum. CONCLUSIONS & INFERENCES: Pacemaker ICC play a prominent role in the expression of motor activity induced by cholinergic activity and our data suggest that cholinergic neurotransmission to ICC affects the pacemaker frequency.

Measurement of intracellular chloride ion concentration in ICC in situ and in explant culture.

BACKGROUND: Chloride channels are proposed to play a central role in the electrical pacemaking mechanism of interstitial cells of Cajal (ICC). A key unknown factor in the consideration of this role is the chloride equilibrium potential (E(Cl)), as determined by the relative concentrations of intra- ([Cl(-)](i)) and extracellular ([Cl(-)](o)) chloride ions. METHODS: To calculate the E(Cl) of ICC, [Cl(-)](i) was measured with the fluorescent chloride indicator N-(6-methoxyquinolyl) acetoethyl ester (MQAE). Pacemaker ICC in explant cultures or in situ, i.e. ICC associated with the myenteric plexus of the small intestine, were loaded with MQAE and fluorescence was measured by laser scanning confocal microscopy. The dye fluorescence was then calibrated against known [Cl(-)](i) by treating the explants or in situ preparations with chloride ionophore and varying bath chloride concentrations. KEY RESULTS: In explants, ICC [Cl(-)](i) was measured as 13 mmol L(-1) with [Cl(-)](o) of 100 mmol L(-1), giving an E(Cl) of -52 mV [corrected]. With [Cl(-)](o) at 166 mmol L(-1), [Cl(-)](i) was 26 mmol L(-1), giving an E(Cl) of -47 mV[corrected]. In situ, ICC [Cl(-)](i) was measured as 26 mmol L(-1) with [Cl(-)](o) of 130 mmol L(-1), giving an E(Cl) of -41 mV [corrected]. Importantly ICC compensate for changes in extracellular chloride by changing [Cl(-)](i) and thus maintain E(Cl). In ICC explant clusters, [Cl(-)](i) was seen to fluctuate, possibly evoked by rhythmic changes in intracellular calcium. CONCLUSIONS & INFERENCES: The intracellular chloride concentration in ICC fluctuates to keep its equilibrium potential constant. The identification of E(Cl) as positive to the resting membrane potential of ICC indicates that opening of chloride channels will depolarize ICC.

Lactobacillus reuteri ingestion and IK(Ca) channel blockade have similar effects on rat colon motility and myenteric neurones.

BACKGROUND: We have previously shown that ingestion of Lactobacillus reuteri may modulate colonic enteric neuron activity but with unknown effects on colon motility. The aim of the present report was to elucidate the neuronal mechanisms of action of the probiotic by comparing the effects on motility of L. reuteri ingestion with blockade of a specific ionic current in enteric neurons. METHODS: We have used intraluminal pressure recordings from ex vivo rat colon segments and whole cell patch clamp recordings from neurons of rat longitudinal muscle myenteric plexus preparations to investigate the effects of L. reuteri and TRAM-34 on colon motility and neurophysiology. The effects of daily feeding of 10(9) L. reuteri bacteria or acute application of TRAM-34 on threshold fluid filling pressure or pulse pressure was measured. KEY RESULTS: Lactobacillus reuteri increased intraluminal fluid filling pressure thresholds for evoking pressure pulses by 51% from 0.47 +/- 0.17 hPa; the probiotic also decreased the pulse pressure amplitudes, but not frequency, by 18% from 3.91 +/- 0.52 hPa. The intermediate conductance calcium-dependent potassium (IK(Ca)) channel blocker TRAM-34 (3 micromol L(-1)) increased filling threshold pressure by 43% from 0.52 +/- 0.22 hPa and reduced pulse pressure amplitude by 40% from 2.63 +/- 1.11 hPa; contraction frequency was unaltered. TRAM-34 (3 micromol L(-1)) reduced membrane polarization, leak conductance and the slow afterhyperpolarization current in 16/16 myenteric rat colon AH cells but 19/19 S cells were unaffected. CONCLUSIONS & INFERENCES: The present results are consistent with L. reuteri enhancing tonic inhibition of colon contractile activity by acting via the IK(Ca) channel current in AH cells.

Neurotransmission in lower esophageal sphincter of W/Wv mutant mice.

To address the controversy surrounding the role of interstitial cells of Cajal (ICC) in nitrergic neurotransmission to gastrointestinal smooth muscle, circular smooth muscle from the lower esophageal sphincter (LES) of W/W(v) wild-type and mutant (ICC-deficient) mice were studied by using intracellular and tension recordings in vitro. Resting membrane potential was more negative, and the spontaneous unitary potentials diminished in mutant mice. In wild-type mice, nerve stimulation induced a biphasic inhibitory junction potential (IJP) consisting of a fast initial IJP followed by a long-lasting slow IJP (LSIJP). The IJP was markedly impaired in a significant proportion of mutant mice, whereas in others it was normal. Pharmacological studies in the mice with markedly impaired IJPs revealed that cholinergic and purinergic components of the nerve-mediated responses appeared intact. In wild-type mice, caffeine hyperpolarized smooth muscle cells, inhibited the initial fast IJP, and completely abolished the LSIJP. In mutant mice, caffeine depolarized smooth muscle cells and abolished the impaired LSIJP but did not affect the initial fast IJP. Immunohistochemical staining for c-Kit confirmed deficiency of ICC in mutant mice with a normal nitrergic IJP. Rings of LES circular smooth muscle from W/W(v) mutant mice generated significantly less spontaneous tone than controls. When tone was restored with carbachol, normal nitrergic LES relaxation was recorded. These data suggest that 1) there is significant variability in the generation of nitrergic neurotransmission in the LES of W/W(v) mutant mice, whereas purinergic and cholinergic neurotransmission are intact; 2) the altered nitrergic responses appear to be associated with abnormal Ca2+-dependent signaling initiated by spontaneous Ca2+ release from sarcoplasmic reticulum in smooth muscle cells; and 3) c-Kit-positive ICC are not essential for nitrergic neurotransmission in mouse LES smooth muscle.

Loss of intramuscular and submuscular interstitial cells of Cajal and associated enteric nerves is related to decreased gastric emptying in streptozotocin-induced diabetes.

Interstitial cells of Cajal (ICC) are associated with afferent innervation and peristalsis of the stomach suggestive of a key role in the pathophysiology of gastroparesis. We studied changes in the density and ultrastructure of ICC and enteric nerves in the streptozotocin-induced diabetes mellitus (STZ-DM) in Wistar rats using immunohistochemistry and electron microscopy. Gastric emptying was studied in vivo by single-photon emission computed tomography. In the STZ-DM antrum, a marked reduction was observed in the density of the intramuscular ICC (ICC-IM) and ICC located at the submucosal border of the circular muscle layer of the antrum (ICC-SM). The surviving ICC showed lamellar bodies and partial vacuolation of the cytoplasm content, loss of connections between ICC-IM and nerves; it appeared that injured ICC-IM developed into fibroblast-like ICC. ICC associated with Auerbach's plexus (ICC-AP) in the antrum and ICC in the fundus were not affected significantly except for a loss of connections with nerve structures. Marked reduction in nerve tissue (Protein Gene Product-9.5 positivity) was also restricted to the muscle layers including nitrergic nerves (neuronal nitric oxide synthase positivity). In vivo assessed gastric emptying was markedly reduced in STZ-DM rats. Our data demonstrate in the STZ-DM rat stomach a decreased density of ICC limited to the antrum and to ICC-IM and ICC-SM, and structural degeneration in ICC-IM and associated nerves with a special emphasis on loss of synaptic connections, accompanied by a decrease in gastric emptying. Hence, in this model of gastroparetic diabetes, regional injury to subsets of ICC and nerves are associated with gastric motor dysfunction.

Substance P activates a non-selective cation channel in murine pacemaker ICC.

Interstitial cells of Cajal (ICC) associated with Auerbach's plexus in the small intestine, provide pacemaker activity to orchestrate peristalsis and mixing. Despite the close apposition between ICC and enteric nerves, little is known about the neural regulation of pacemaker activity. The present study pursues the hypothesis that substance P can affect pacemaker activity through action on non-selective cation channels. Cell-attached and inside-out patch clamp studies were performed on isolated ICC in short-term cultures that provided evidence that substance P increases open probability or initiates activity in non-selective cation channels in ICC. The single-channel conductance is approximately 25 pS and in the on-cell configuration the activity can occur in a rhythmic fashion. Patches contained 1-10 channels and were most often accompanied by a approximately 12 pS chloride channel that was also activated by substance P. In a recently developed preparation that allows patch clamping in ICC in their natural environment within tissue, i.e. in situ, the presence of the channel and substance P activation was confirmed. The non-selective cation channel is one of the channels that initiate intestinal pacemaker activity and the present study provides further single-channel data on this critical channel. Because of the close proximity of enteric motor and sensory nerves to ICC, these data provide a potential mechanism underlying neural regulation of pacemaker activity. The data also indicate that neurokinergic pharmacology is a promising avenue for excitation of the intestinal pacemaker system.