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Biomedical subjects

R K Mittal

Publications and source records attributed to R K Mittal.

At least 19 recordsLinked to original sources
PubMed2006

Oesophago-gastric junction opening function: assessment using ultrasound imaging and the effects of atropine.

Relaxation and opening of the oesophago-gastric junction (OGJ) is crucial for oesophageal transport. A novel ultrasound technique was used to determine OGJ opening, before and after atropine, in 12 normals. An ultrasound probe, a solid-state pressure transducer and an infusion tube were placed inside a 20-mm diameter bag, which was placed across the OGJ. At various bag pressures ultrasound transducer was pulled across the bag. Acquired B-mode ultrasound images were converted into M-mode image to display the oesophagus, OGJ and stomach. At low bag-pressure (< 20 mmHg), the OGJ but not oesophagus and stomach, is collapsed around the bag. Increasing bag pressure results in gradual opening of the OGJ from distal end. M-mode image identified the narrowest region of OGJ and corresponding cross-sectional area (CSA) was measured. Mean bag pressure to initial OGJ opening was 18 mmHg. Linear relationship between bag-pressure and OGJ-CSA was observed. Atropine reduced opening bag pressure and shifted the OGJ pressure-CSA curve upward without altering slope, i.e. compliance. Our novel ultrasound technique to study the OGJ opening function shows two distinct components; firstly, related to the tonic OGJ contraction and secondly, to passive or viscoelastic properties of the OGJ.

Adult↗
PubMed2005

Flow across the gastro-esophageal junction: lessons from the sleeve sensor on the nature of anti-reflux barrier.

The principles of fluid flow are critical to the understanding of flow across the gastro-esophageal (GE) junction or gastro-esophageal reflux. The mechanism by which sleeve sensor measures lower esophageal sphincter (LES) pressure is also based on the principle of fluid flow across the GE junction and can provide important insights into the nature of anti-reflux barrier. We present arguments regarding the role of the length of LES, intra-abdominal length of the LES, flap valve at the GE junction and the angle of His on the strength of anti-reflux barrier. Our conclusion is that in the presence of normal anatomy of the GE junction (absence of hiatus hernia) the pressure at the GE junction is the most important determinant of the strength of anti-reflux barrier.

Animals↗
PubMed2005

Oesophageal wall stress and muscle hypertrophy in high amplitude oesophageal contractions.

Excessive wall stress is a known stimulus for muscle growth. We recently reported a thickened muscularis propria in patients with high amplitude oesophageal contractions (HAEC). The goal of this study was to determine oesophageal wall stress in normal subjects and patients with HAEC. A manometry catheter equipped with a high frequency ultrasound (US) transducer was used to record pressure and US images simultaneously in 10 healthy subjects and 11 patients with HAEC. Recordings were obtained at 2 and 10 cm above the lower oesophageal sphincter during water swallows. The changes in circumferential wall stress during oesophageal contraction in both groups are relatively small because of an increase in the wall thickness-to-radius ratio during contraction. Patients show a greater muscle thickness than normal subjects at rest and at the peak of contraction. The wall stress in patients is elevated at the 2 cm but not at the 10-cm level as compared to normal subjects. Wall strain is not different between the two groups. Increase in wall thickness during oesophageal contraction maintains low wall stress. A greater wall stress in patients with HAEC may be a stimulus for the increased wall thickness.

Adult↗
PubMed2005

Genetic variability in triticale x bread wheat derivatives under normal and phosphorus stress regimes.

Twenty six hexaploid triticale (X Triticosecale Wittmack) X bread wheat (Triticum aestivum L. em Thell) derivatives, along with 2 bread wheat and 2 triticale checks, were grown in normal and P-stress environments. Spikes/plant and grain yield/plant, followed by peduncle length, Were the most sensitive to phosphorus deficiency, which also caused a delay in heading and maturity. The heritability and genetic advance for grain yield/plant were high in the stress environment, reflecting the effectiveness of direct selection. The 1000-grain weight, grains/spike and plant height were the important traits for phenotypic selections in both the environments.

Bread↗
PubMed2004

Review article: supra-oesophageal manifestations of gastro-oesophageal reflux disease and the role of night-time gastro-oesophageal reflux.

Gastro-oesophageal reflux disease (GERD) has been associated with a variety of supra-oesophageal symptoms, including asthma, laryngitis, hoarseness, chronic cough, frequent throat clearing and globus pharyngeus. GERD may be overlooked as the underlying mechanism for these symptoms because typical GERD symptoms may be absent, despite abnormal oesophageal acid exposure. Two basic mechanisms linking GERD with laryngeal symptoms have been proposed: direct contact of gastric acid with the upper airway, in some cases due to micro-aspiration, and a vagovagal reflex triggered by acidification of the distal portion of the oesophagus. Gastro-oesophageal reflux (GER) during sleep is believed to be an important mechanism for the development of supra-oesophageal complications of GERD, such as asthma and idiopathic pulmonary fibrosis (IPF). Several physiological changes during sleep, including prolonged oesophageal acid contact time, decreased upper oesophageal sphincter pressure, increased gastric acid secretion, decreased salivation, decreased swallowing and a decrease in conscious perception of acid, render an individual more susceptible to reflux-induced injury. Supra-oesophageal symptoms often improve in response to aggressive acid-suppressive therapy. However, many unanswered questions remain regarding the appropriate approach to diagnosis and treatment of patients with GERD-related supra-oesophageal symptoms. In this article we review the relationship between supra-oesophageal symptoms and GERD and, where possible, highlight the evidence supporting the role of night-time reflux as a contributing factor to these symptoms.

Asthma↗
PubMed2004

Oesophageal wall stretch: the stimulus for distension induced oesophageal sensation.

Recently, we reported a novel ultrasound technique to assess the biomechanical properties of the oesophagus in humans. To investigate whether the oesophageal sensation induced by oesophageal distension correlates with wall tension, wall stress or wall strain, we studied 20 healthy subjects using a manometry catheter equipped with a high-compliance bag and a high-frequency intraluminal ultrasound probe. Oesophageal distensions were performed by injecting 1-20 mL water into the bag for 20-30 s. Subjects scored the nature (heartburn or chest pain) and severity of sensation in response to distension, before and after atropine (15 microg kg(-1), i.v.). Ultrasound images of oesophagus were digitized and measurements were made to calculate oesophageal wall tension, stress and strain during distensions. Subjects experienced mostly heartburn, not chest pain, in response to oesophageal distension. Oesophageal wall strain and bag pressures correlated best with the oesophageal sensation. Atropine reduced bag pressure but did not affect the distension induced heartburn and chest pain. We conclude that heartburn is a common sensation in response to oesophageal distension in normal subjects. A strong correlation between wall strain and oesophageal sensation suggests that the wall stretch is the stimulus for nociceptive mechanoreceptors of the oesophagus.

Adult↗
PubMed2001

Evaluation of omeprazole in the treatment of reflux laryngitis: a prospective, placebo-controlled, randomized, double-blind study.

OBJECTIVES: Proton-pump inhibitors are often recommended in the treatment of laryngitis secondary to gastric reflux. Despite prospective treatment studies reporting high efficacy, only one previous report has been placebo-controlled and blinded. The objective of this study was to determine the efficacy of omeprazole in treating proven reflux laryngitis. STUDY DESIGN: Prospective, placebo-controlled, randomized, double-blind clinical trial. METHODS: Fifty-three patients with one or more reflux laryngitis symptoms were recruited to undergo 24-hour dual-channel pH probe testing. Thirty patients with more than four episodes of laryngopharyngeal reflux were enrolled. By random assignment, 15 patients received 40 mg omeprazole twice a day and the other 15 received placebo for a period of 2 months. Symptoms (hoarseness, throat pain, lump in throat sensation, throat clearing, cough, excessive phlegm, dysphagia, odynophagia, and heartburn) and endoscopic laryngeal signs (erythema, edema, and mucus accumulation) were recorded initially, at 1 month, and 2 months. RESULTS: In general, most symptom scores improved over time for both the omeprazole and placebo groups. Hoarseness, when patients begin with low hoarseness symptom scores, and throat clearing improved significantly more in patients on omeprazole than in those on placebo during the 2-month study. Throat pain, lump in throat sensation, excessive phlegm, difficulty swallowing, pain with swallowing, and heartburn showed improvement in both treatment arms, signifying the possibility of a placebo effect. Endoscopic laryngeal signs did not change significantly over the course of the study for either treatment group. CONCLUSIONS: A placebo effect appears to exist in the treatment of reflux laryngitis. However, hoarseness, when initially scored low, and throat clearing resulting from reflux laryngitis are effectively treated by omeprazole.

Adult↗
PubMed2001

Relationship between esophageal muscle thickness and intraluminal pressure: an ultrasonographic study.

A number of studies show a close temporal relationship between the rate of change in muscle thickness as detected by high-frequency intraluminal ultrasonography (HFIUS) and intraluminal pressure measured by manometry. There is a marked variability in esophageal contraction amplitude from one swallow to another at a given level in the esophagus and along the length of the esophagus. Furthermore, peristaltic pressures are higher in the distal compared with the proximal esophagus. The goal of this study was to evaluate the relationship between the baseline and peak muscle thickness and the contraction amplitude during swallow-induced contractions along the length of the esophagus. Fifteen normal subjects were studied using simultaneous esophageal pressures and HFIUS or HFIUS alone. Recordings were made during baseline and standardized swallows in the lower esophageal sphincter (LES) and at 2, 4, 6, 8, and 10 cm above the LES. HFIUS images were digitized, and esophageal muscle thickness and peak contraction amplitudes were measured. In the resting state, muscle thickness is higher in the LES compared with the rest of the esophagus. Baseline muscle thickness is also significantly higher at 2 cm vs. 10 cm above the LES. In a given subject and among different subjects, there is a good relationship between peak muscle thickness and peak peristaltic pressures (r = 0.55) at all sites along the length of the esophagus. The positive correlation between pressure and muscle thickness implies that the mean circumferential wall stress is fairly uniform from one swallow to another, irrespective of the contraction amplitude.

Adult↗
PubMed2001

Sustained esophageal contraction: a motor correlate of heartburn symptom.

Heartburn occurs in the presence as well as the absence of acid reflux. We searched for a motor correlate of heartburn. Twelve subjects with heartburn were studied with 24-h synchronized pressure, pH, and high-frequency intraluminal ultrasound (HFIUS) imaging of the esophagus. The HFIUS images were analyzed every 2 s for a period of 2 min before and 30 s after the onset of heartburn during 20 acid reflux-positive and 20 acid reflux-negative heartburn episodes. The esophageal muscle thickness was measured as a marker of contraction. Esophageal pressure and HFIUS images were recorded during the Bernstein test in 15 subjects. Sustained esophageal contractions (SECs) were identified during 13 of 20 heartburn episodes associated with acid reflux and 15 of 20 heartburn episodes without acid reflux. SECs were detected during 2 of 40 matched control periods only (P < 0.05). The duration of SECs was 44.9 +/- 26.9 s. The Bernstein test reproduced heartburn symptoms in 8 of 15 subjects. SECs were identified during 6 of 8 (75%) Bernstein-positive and in 1 of 7 (14.3%) Bernstein-negative tests (P = 0.04). We conclude that a SEC precedes both spontaneous and induced heartburn symptoms and may be the cause of heartburn sensation.

Adult↗
PubMed2000

The effect of mechanoreceptor stimulation of the laryngopharynx on the oesophago-gastric junction.

Stimulation of the pharynx by injection of minute amounts of water induces prolonged period of lower oesophageal sphincter (LOS) relaxation and augmentation of the crural diaphragm (CD) contraction. The purpose of this study was to determine the effects of stimulating mechano-receptors at the laryngopharynx on the LOS and CD by using an air pulse stimulation device. Air pulses were delivered via the internal channel of a flexible endoscope. Oesophageal, LOS, and CD pressures; CD electromyogram; and oesophageal pH 5 cm above the LOS were recorded in nine healthy subjects. Stimulation of the laryngopharynx induced LOS relaxation in the absence of swallow and oesophageal peristalsis. The stimulation of epiglottis and arytenoid produced higher incidence of LOS relaxation compared to the base of tongue. The magnitude of LOS relaxation differed significantly between the three anatomical sites, with greater relaxation occurring at the epiglottis and arytenoid compared with the base of the tongue. None of the LOS relaxations induced by laryngeal stimulation resulted in inhibition of the CD or gastroesophageal reflux. We conclude that stimulation of the laryngopharyngeal mechanoreceptors induces LOS but not CD relaxation. The LOS relaxation induced by laryngopharyngeal stimulation is not accompanied by acid reflux in fasting state.

Adult↗
PubMed2000

Evidence for a peripheral mechanism of esophagocrural diaphragm inhibitory reflex in cats.

The esophagogastric junction (EGJ) is guarded by two sphincters, a smooth muscle lower esophageal sphincter (LES) and a skeletal muscle crural diaphragm. These two sphincters relax simultaneously under certain physiological conditions, i.e., swallowing, belching, vomiting, transient LES relaxation, and esophageal distension. Esophageal distension-induced crural diaphragm relaxation is mediated through vagal afferents that are thought to exert inhibitory influence on the central mechanism (brain stem) of crural diaphragm contraction. We conducted studies in 10 cats to determine whether a mechanism of crural diaphragm relaxation was located at the level of the neuromuscular junction and/or muscle. Stimulation of the crural diaphragm neuromuscular junction through 1) the electrodes implanted in the muscle and 2) the bilateral phrenic nerve resulted in an increase in EGJ pressure. Nicotinic receptor blockade (pancuronium, 0.2 mg/kg) abolished the EGJ pressure increase caused by electrical stimulation of the neuromuscular junction. Esophageal distension and bolus-induced secondary esophageal peristalsis caused relaxation of the EGJ during the stimulation of the neuromuscular junction. Bilateral phrenicotomy and vagotomy had no influence on this relaxation. These data suggest the existence of a peripheral mechanism of crural diaphragm inhibition. This peripheral inhibitory mechanism may reside at the level of either the neuromuscular junction or the skeletal muscle.

Animals↗
PubMed1999

Sustained esophageal contraction: a marker of esophageal chest pain identified by intraluminal ultrasonography.

BACKGROUND & AIMS: Intraluminal pressure recording systems have not demonstrated predictable esophageal motor correlates of unexplained chest pain. This study used continuous high-frequency intraluminal ultrasonography to characterize esophageal contraction at the time of spontaneous and provoked chest pain. METHODS: Intraluminal pressure, pH, and ultrasound images of the esophagus were recorded for a maximum of 24 hours in 10 subjects with unexplained chest pain. Changes in esophageal muscle thickness were measured as a marker of muscle contraction. Ten additional subjects with suspected esophageal chest pain were studied after edrophonium chloride injection to provoke symptoms. Ten healthy subjects were studied as controls. RESULTS: Eighteen of 24 spontaneous chest pain episodes were preceded by a sustained esophageal contraction (SEC) detected on ultrasonography (mean duration, 68.0 seconds). This motor pattern was not accompanied by changes in intraluminal pressure. Four of 24 asymptomatic control periods were accompanied by SEC, although these contractions were of shorter mean duration (29.0 seconds; P < 0.001). SEC was observed in 5 subjects with a positive chest pain response to edrophonium and in none of the 5 subjects with a negative response. SEC was not detected in normal subjects. CONCLUSIONS: There is a strong temporal correlation between a previously unrecognized esophageal motor event, SEC, and both spontaneous and provoked esophageal chest pain.

Adolescent↗
PubMed1999

Cholinergic blockade inhibits gastro-oesophageal reflux and transient lower oesophageal sphincter relaxation through a central mechanism.

BACKGROUND: Atropine, an anticholinergic agent with central and peripheral actions, reduces gastro-oesophageal reflux (GOR) in normal subjects and patients with gastro-oesophageal reflux disease (GORD) by inhibiting the frequency of transient lower oesophageal sphincter relaxation (TLOSR). AIMS: To compare the effect of methscopolamine bromide (MSB), a peripherally acting anticholinergic agent, with atropine on the rate and mechanism of GOR in patients with GORD. METHODS: Oesophageal motility and pH were recorded for 120 minutes in 10 patients with GORD who were studied on three separate occasions. For the first two recording periods, either atropine (15 microg/kg bolus, 4 microg/kg/h infusion) or saline were infused intravenously. MSB (5 mg orally, four times daily) was given for three days prior to the third recording period. RESULTS: Atropine significantly reduced basal LOS pressure (12.6 (0.17) mm Hg to 7.9 (0.17) mm Hg), and the number of TLOSR (8.1 (0.56) to 2.8 (0. 55)) and reflux episodes (7.0 (0.63) to 2.0 (0.43)) (p<0.005 for all comparisons). MSB reduced basal LOS pressure (12.6 (0.17) to 8.7 (0. 15) mm Hg, p<0.005), but had no effect on the frequency of TLOSR (8. 1 (0.56) to 7.5 (0.59)) and reflux episodes (7.0 (0.63) to 4.9 (0. 60)) (p>0.05). CONCLUSION: In contrast to atropine, MSB has no effect on the rate of TLOSR or GOR in patients with GORD. Atropine induced inhibition of TLOSR and GOR is most likely mediated through a central cholinergic blockade.

Adult↗
PubMed1999

Lower esophageal sphincter monitoring with sphinctometer: in vitro and in vivo studies.

The sphinctometer is a solid-state device system for prolonged ambulatory recordings of the lower esophageal sphincter (LES) pressure. The aims of this study were to determine 1) the pressure sensitivity and the latency of sphinctometer responses in vitro, 2) if the sphinctometer can record transient LES relaxations (TLESR) in vivo, and 3) if the currently accepted criteria for TLESR are applicable to sphinctometer recordings. Different segments of the sphinctometer were positioned in a chamber at known pressures to assess the sphinctometer readings as well as the latency of the response. Ten healthy subjects were investigated with the use of a solid-state transducer sphinctometer assembly and a pH probe for 4 h. The LES pressure was analyzed during baseline periods, swallow-induced LES relaxations (SILESR), and LES relaxations associated with acid reflux episodes (pH <4) (presumed TLESRs). Our results showed that sphinctometer readings were linearly related to the chamber pressure and the length of the segment exposed to the pressure; however, the latter was considerably underestimated. We also found that sphinctometer segments of equal length but at different levels showed different pressure readings, the mean response time of sphinctometer was 0.25 s, and sphinctometer output was susceptible to temperature changes of the environment. In humans, only 25 of 45 episodes (64%) and 17 of 22 episodes (77%) were detected by the sphinctometer as being SILESRs and TLESRs, respectively. The pattern of the LES pressure during acid reflux events resembled classical TLESR. We concluded that the sphinctometer is a useful device for determining qualitative changes in LES pressure. However, its major limitations are pressure underestimation, different sensitivity of various segments, pressure drifts, and underscoring of LES relaxations.

Adolescent↗
PubMed1998

The spectrum of diaphragmatic hernia.

Diaphragmatic hernias are among the most common abnormalities of the gastrointestinal tract. Those with significant paraesophageal features may require surgical intervention to prevent potentially lethal complications. By contrast, 90% of patients with sliding hiatal hernias respond favorably to behavior modification and antisecretory drug therapy.

Aged↗
PubMed1998

Effect of atropine on gastro-oesophageal reflux and transient lower oesophageal sphincter relaxations in patients with gastro-oesophageal reflux disease.

BACKGROUND: Atropine reduces the rate of reflux episodes in normal subjects by inhibition of transient lower oesophageal sphincter (LOS) relaxations. The aim of this study was to investigate the effect of atropine on the rate and mechanisms of reflux in patients with reflux disease. METHODS: Oesophageal motility and pH were recorded for one hour after a meal in 15 patients with reflux disease. On separate days, atropine (15 micrograms/kg bolus intravenously, 4 micrograms/kg/h infusion) or saline were given and maintained for the recording period. RESULTS: Atropine significantly reduced basal LOS pressure from 7.1 (2.2) to 2.9 (1.3) mm Hg (mean (SEM)). Atropine also reduced the rate of reflux episodes from 5.0 (2.0-8.75) to 1.0 (0-6.25) per hour (median (interquartile range)) largely because of a decrease in the rate of transient LOS relaxations from 2.0 (0-4.75) to 0 (0-0) per hour and abolition of reflux during swallow induced LOS relaxation. There was no change in the rate of reflux episodes because of absent basal LOS pressure. CONCLUSIONS: Atropine inhibits reflux in patients with reflux disease largely by inhibition of transient LOS relaxations and swallow induced LOS relaxation. These findings suggest that pharmacological control of reflux through control of transient LOS relaxations is possible in patients with reflux disease.

Adult↗