Nicholas E. Diamant's research while affiliated with Queen's University and other places

Publications (109)

Article
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Background and aims: Our aim is to review the literature and provide guidelines for the assessment of uninvestigated dysphagia. Methods: A systematic literature search identified studies on dysphagia. The quality of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development, and Evaluat...
Article
Objectives: Achalasia is a chronic, progressive, and incurable esophageal motility disease. There is clinical uncertainty about which treatment should be recommended as first-line therapy. Our objective was to evaluate the effectiveness of pneumatic dilation compared with laparoscopic Heller myotomy with partial fundoplication in improving achalas...
Article
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Abstract Dysphagia screening often includes administration of water. This study assessed the accuracy in identifying dysphagia with each additional teaspoon of water. The original research of the TOR-BSST(©) permitted this assessment. Trained nurses from acute and rehabilitation facilities prospectively administered the TOR-BSST(©) to 311 eligible...
Article
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Tests for dysphagia serve as either assessment or screening tools. To be clinically useful these tools must be reliable, validated with proper psychometric techniques, and feasible. In a previous systematic review, only two screening tools met these criteria from the studies in stroke patients. There are no such systematic reviews assessing the ava...
Chapter
The esophagus is a muscular tube that serves to propel the ingested food to the stomach by sequential, aborally progressive contraction of the esophageal circular muscle in concert with shortening of the esophagus effected by longitudinal muscle contraction. Whereas esophageal muscle contraction in the proximal striated muscle segment is activated...
Conference Paper
PURPOSE To compare pneumatic dilatation (PD) and laparoscopic Heller myotomy (HM) in treatment of achalasia using esophageal emptying as assessed by timed barium esophagram (TBE). METHOD AND MATERIALS 55 patients with achalasia confirmed with manometry, endoscopy, and imaging were prospectively randomized to undergo laparoscopic myotomy (n=29) or...
Article
Two case reports demonstrate the paradoxical occurrence of achalasia many years after the successful surgical treatment of gastroesophageal reflux disease (GERD). These patients had remedial surgery laparoscopically. The three types of achalasia syndromes that can follow antireflux surgery are discussed. In type 1, primary achalasia is misdiagnosed...
Article
Swallowing occurs about 600 times a day, and the esophagus is an essential passageway for the swallowed bolus to arrive in the stomach. Central control of the swallowing process is required for orderly contraction of muscles in the mouth, pharynx, upper esophageal sphincter, and upper esophagus. These regions are striated muscle and need guiding mo...
Article
Patients with irritable bowel syndrome (IBS) have abnormal cortical responses to rectal distension and grey matter thinning in brain areas associated with nociception. These abnormalities may be driven by white matter changes and individual factors. Therefore, we tested the hypothesis that WM subserving the pain system is compromised in IBS, and th...
Article
Ramon y Cajal discovered interstitial cells in the pancreas associated with intrinsic nerves. It was our aim to provide evidence for or against the hypothesis that the pancreatic duct harbors interstitial cells of Cajal (ICCs) that may function as pacemakers for duct motility. We used immunohistochemistry using c-Kit as the ICC marker and protein g...
Article
To assess the effect of nitric oxide (NO) on the large conductance potassium channel (BK(Ca)) in isolated circular (CM) and sling (SM) muscle cells and muscle strips from the cat lower esophageal sphincter (LES) to determine its regulation of resting tone and relaxation. Freshly enzymatically-digested and isolated circular smooth muscle cells were...
Conference Paper
PURPOSE To determine how changes in esophageal emptying on timed barium esophagram (TBE) after treatment of achalasia correlate with clinical measures of achalasia severity. METHOD AND MATERIALS 55 patients with achalasia confirmed by manometry, endoscopy and radiologic testing were enrolled in a clinical trial comparing pneumatic dilatation and s...
Article
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For clinical trials in functional bowel disorders (FBD), the definition of a responder, one who meets the predefined criteria for a clinical response, is needed. Factors that determine clinical response aside from treatment itself are unknown. The aim of this study was to determine what baseline and post-treatment factors affect treatment response....
Article
Brain imaging studies have identified abnormal rectal-evoked responses and cortical thinning in patients with irritable bowel syndrome (IBS). However, it is not known whether these abnormalities are pre-existing or develop as result of long-term IBS. Therefore, we tested whether abnormal structural gray matter integrity in IBS correlates with indiv...
Article
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Purpose: This study expands upon a mixed-methods pilot project that reported SLPs examples of natural state liquids when educating patients prescribed to thickened liquids. Sequentially, purposes were (1) do the viscosities of these reported natural state nectar, honey and pudding materials differ significantly from the viscosity of their VaribarÒ...
Article
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The objectives of this study were (1) to compare and contrast the psychological issues perceived by patients with oropharyngeal dysphagia and explore if the differences relate to recovery trajectory, and (2) to determine whether patients, caregivers, and clinicians had different perceptions of how psychological issues interacted with the lung and n...
Article
The implications of the Rome III recommendations to change the irritable bowel syndrome (IBS) subtype criteria for stool pattern are unknown. (1) Determine the level of agreement between Rome II and Rome III subtypes and (2) compare the behaviors of Rome II and Rome III subtypes over time. Female patients (n=148) with Rome II defined IBS were prosp...
Article
Dysphagia occurs in 55% of all acute stroke patients. Early identification of dysphagia from screening can lead to earlier treatments and thereby reduce complications. We designed and validated a new bedside dysphagia screening tool-the Toronto Bedside Swallowing Screening Test (TOR-BSST) for stroke survivors in acute and rehabilitative settings. T...
Article
Patients with functional gastrointestinal disorders treated with tricyclic antidepressants sometimes report nongastrointestinal symptoms; it is unclear whether these are drug side effects or reflect a behavioral tendency to report symptoms. We evaluated whether symptoms reported before treatment with a tricyclic antidepressant (desipramine) increas...
Article
To compare and contrast clinician, patient, and caregiver perspectives to generate all important and salient items for a new scale to measure medical consequences relevant to adult patients with dysphagia. Six focus groups (three with clinicians, two with patients, and one with caregivers) were conducted with a total of 33 participants. Through the...
Article
A composite synthesized relaxation oscillator (SRO), whose output exhibits two types of interrelated rhythmic activities, is proposed. A slow rhythmic activity is present at all times, and it controls the appearance of a faster bursting activity that is not always present. The second-order SRO dynamics for producing omnipresent and labile rhythmic...
Article
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Interstitial cells of Cajal (ICC) have been proposed as stretch receptors for vagal afferent nerves in the stomach based on immunohistochemical studies. The aim of the present study was to use electron microscopy and the anterograde degeneration technique to investigate ultrastructural features and survival dependency of ICC associated with vagal a...
Article
Various instruments may be used to measure health-related quality of life in patients with achalasia. We administered four patient-centered measures used for evaluation of achalasia severity [an achalasia severity questionnaire we developed previously, an achalasia symptom checklist, the Gastrointestinal Quality-of-Life Index (GIQLI), and the Medic...
Article
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The feline gastrointestinal (GI) tract is an important model for GI physiology but no immunohistochemical assessment of interstitial cells of Cajal (ICC) has been performed because of the lack of suitable antibodies. The aim of the present study was to investigate the various types of ICC and associated nerve structures in the pyloric sphincter reg...
Article
Assessing health related quality of life (HRQOL) is becoming more important in research and clinical care. However, little information is available on the performance of HRQOL questionnaires for the functional bowel disorders (FBD). The aims of this study were to (a) understand the performance of the Sickness Impact Profile (SIP) and IBS-QOL for th...
Article
The SNARE protein syntaxin 1A (Syn1A) is known to inhibit delayed rectifier K(+) channels of the K(v)1 and K(v)2 families with heterogeneous effects on their gating properties. In this study, we explored whether Syn1A could directly modulate K(v)4.3, a rapidly inactivating K(v) channel with important roles in neuroendocrine cells and cardiac myocyt...
Article
SNARE proteins, syntaxin-1A (Syn-1A) and SNAP-25, inhibit delayed rectifier K(+) channels, K(v)1.1 and K(v)2.1, in secretory cells. We showed previously that the mutant open conformation of Syn-1A (Syn-1A L165A/E166A) inhibits K(v)2.1 channels more optimally than wild-type Syn-1A. In this report we examined whether Syn-1A in its wild-type and open...
Article
In low or absence of glucose, alpha-cells generate rhythmic action potentials and secrete glucagon. alpha-Cell T-type Ca(2+) channels are believed to be pacemaker channels, which are expected to open near the resting membrane potential (around -60 mV) to initiate a small depolarization. A previous publication, however, showed that alpha-cell T-type...
Article
Glucose regulates pancreatic islet alpha-cell glucagon secretion directly by its metabolism to generate ATP in alpha-cells, and indirectly via stimulation of paracrine release of beta-cell secretory products, particularly insulin. How the cellular substrates of these pathways converge in the alpha-cell is not well known. We recently reported the us...
Article
To determine the incidence of dysphagia and associated pulmonary compromise in stroke patients through a systematic review of the published literature. Databases were searched (1966 through May 2005) using terms "cerebrovascular disorders," "deglutition disorders," and limited to "humans" for original articles addressing the frequency of dysphagia...
Article
The lower esophageal sphincter (LES) has a circular muscle component exhibiting spontaneous tone that is relaxed by nitric oxide (NO) and a low-tone sling muscle that contracts vigorously to cholinergic stimulation but with little or no evidence of NO responsiveness. This study dissected the responses of the sling muscle to nitrergic innervation in...
Article
We recently reported a transgenic [mouse insulin promoter (MIP)-green fluorescent protein (GFP)] mouse in which GFP expression is targeted to the pancreatic islet beta-cells to enable convenient identification of beta-cells as green cells. The GFP-expressing beta-cells of the MIP-GFP mouse were functionally indistinguishable from beta-cells of norm...
Article
To develop a measure of disease-specific health-related quality of life for achalasia for use as an outcome measure in clinical trials. We generated a list of potential items for a measure of disease-specific health-related quality of life for achalasia by semistructured interviews with seven persons with achalasia, and by expert opinion. We then u...
Article
Potassium channels are important contributors to membrane excitability in smooth muscles. There are regional differences in resting membrane potential and K(+)-channel density along the length of the feline circular smooth muscle esophagus. The aim of this study was to assess responses of K(+)-channel currents to cholinergic (ACh) stimulation along...
Article
As shown in the per protocol analysis of a recent randomized, controlled trial, when tolerated, Desipramine (DES) is effective over placebo (PLA) in treating moderate-to-severe functional bowel disorders (FBD). Clinical experience suggests that the benefit from tricyclic antidepressants (TCA) in FBD can be achieved at doses lower than those used to...
Article
Irritable bowel syndrome (IBS) is subtyped as IBS with diarrhea (IBS-D) or IBS with constipation (IBS-C) based on Rome II guidelines. The remaining group is considered as having mixed IBS (IBS-M). There is no standard definition of an alternator (IBS-A), in which bowel habit changes over time. Our aim was to use Rome II criteria to prospectively as...
Article
A hallmark symptom of irritable bowel syndrome (IBS) is a lower pain threshold during rectal distension, but the mechanism underlying this disorder remains unclear. Examining the relationship between physiological and perceptual responses to rectal distension can provide insight into the underlying peripheral or central dysfunction in IBS. Therefor...
Article
We hypothesized that regional differences in electrophysiological properties exist within the musculature of the feline lower esophageal sphincter (LES) and that they may potentially contribute to functional asymmetry within the LES. Freshly isolated esophageal smooth muscle cells (SMCs) from the circular muscle and sling regions within the LES wer...
Article
In humans and cats, muscle from the lower esophageal sphincter (LES) circular region exhibits greater spontaneous tone than LES sling muscle, whereas the sling muscle is much more responsive to cholinergic stimulation. Despite physiological and pharmacological evidence for the presence of L-type Ca2+ channel current (ICa,L) activity in LES circular...
Article
Within muscular equivalents of cat lower esophageal sphincter (LES), the circular muscle develops greater spontaneous tone, whereas the sling muscle is more responsive to cholinergic stimulation. Smooth muscle contraction involves a combination of calcium release from stores and of calcium entry via several pathways. We hypothesized that there are...
Article
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The present study was designed to obtain a comprehensive view of the dysphagia assessment practice patterns of speech-language pathologists and their opinion on the importance of these practices using survey methods and taking into consideration clinician, patient, and practice-setting variables. A self-administered mail questionnaire was developed...
Article
Studies of antidepressants and psychological treatments in functional bowel disorders (FBD) are methodologically limited. The aim of this study was to assess the clinical efficacy and safety of cognitive-behavioral therapy (CBT) against education (EDU) and desipramine (DES) against placebo (PLA) in female patients with moderate to severe FBD (irrit...
Article
We recently reported that non-secretory gastrointestinal smooth muscle cells also possessed SNARE proteins, of which SNAP-25 regulated Ca(2+)-activated (K(Ca)) and delayed rectifier K(+) channels (K(V)). Voltage-gated, long lasting (L-type) calcium channels (L(Ca)) play an important role in excitation-contraction coupling of smooth muscle. Here, we...
Article
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Delayed-rectifier K+ channels (KDR) are important regulators of membrane excitability in neurons and neuroendocrine cells. Opening of these voltage-dependent K+ channels results in membrane repolarization, leading to the closure of the Ca2+channels and cessation of insulin secretion in neuroendocrine islet β cells. Using patch clamp techniques, we...
Article
Rectal stimulation under normal or pathological conditions evokes numerous sensations. Previous studies have examined rectal stimulation-evoked pain and urge to defecate, but discrepancies in the findings remain because of the different methodologies used in each study and the reporting of sensations only at the end of or after the applied stimuli....
Article
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Cognate soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are now known to associate the secretory vesicle with both the target plasma membrane and Ca(2+) channels in order to mediate the sequence of events leading to exocytosis in neurons and neuroendocrine cells. Neuroendocrine cells, particularly insulin-secr...
Article
The plasma membrane-associated soluble N-ethylmaleimide-sensitive factors attachment protein receptors (SNAREs), synaptosome-associated protein of 25 kilodaltons (SNAP-25), and syntaxin 1A, have been found to physically interact with and functionally modify membrane-spanning ion channels. Studies were performed in cat esophageal body and lower esop...
Article
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We have characterized ion-channel identity and density differences along the feline smooth muscle esophagus using patch-clamp recording. Current clamp recording revealed that the resting membrane potential (RMP) of esophageal smooth muscle cells (SMC) from the circular layer at 4 cm above the lower esophageal sphincter (EBC4; LES) were more depolar...
Article
There are no objective differences in neural elements that explain regional differences in neural influences along the smooth muscle (SM) esophageal body (EB). Regional differences in muscle properties are present in the lower esophageal sphincter (LES). This study examines whether regional differences in SM properties exist along the EB and are re...
Article
Central control of swallowing is regulated by a central pattern generator (CPG) positioned dorsally in the solitary tract nucleus and neighboring medullary reticular formation. The CPG serially activates the cranial nerve motor neurons, including the nucleus ambiguus and vagal dorsal motor nucleus, which then innervate the muscles of deglutition. T...
Article
The whole cell patch-clamp technique was used to investigate whether there were inwardly rectifying K(+) (K(ir)) channels in the longitudinal muscle of cat esophagus. Inward currents were observable on membrane hyperpolarization negative to the K(+) equilibrium potential (E(k)) in freshly isolated esophageal longitudinal muscle cells. The current-v...
Article
The functional role of brainstem nitric oxide (NO) in swallowing and esophageal peristalsis remains unknown. We examined the effects of blockade of central nervous system (CNS) NO synthase (NOS) on swallowing and on primary and secondary peristalsis. (1) The effect of intravenous (IV) NOS inhibitor N(G)-nitro-L-arginine (L-NNA) on swallowing and sw...
Article
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For patients with painful functional bowel disorders (FBD), physicians frequently make diagnostic and treatment decisions based on the severity of the pain reported; patients with severe painful complaints may receive extensive diagnostic tests and treatments. Therefore, it would be important to determine what clinical factors contribute to the jud...
Article
Full-text available
There has been growing interest in the investigation of health-related quality of life (HRQOL) among patients with gastrointestinal (GI) disorders. We recently reported on the development and preliminary validation of the IBS-QOL, a specific quality-of-life measure for irritable bowel syndrome (IBS). The aim of this study was to determine the longi...
Article
Scintigraphy remains the gold standard to study gastric emptying. The technique is onerous and normal values vary between centers. Standardized protocols, although desirable, are not presently available. We validated a simplified scintigraphic protocol in a multicenter setting. In 69 healthy volunteers from seven Canadian institutions, gastric empt...