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Biomedical subjects

R C Gill

Publications and source records attributed to R C Gill.

17 recordsLinked to original sources
PubMed1990

Prolonged ambulant recordings of small bowel motility demonstrate abnormalities in the irritable bowel syndrome.

Continuous 72-h recordings of duodenojejunal contractile activity were obtained from 20 freely ambulant subjects; pressure was detected by two strain-gauge sensors incorporated in a transnasal catheter attached to an encoder and a miniature tape recorder. The subjects were 12 patients with irritable bowel syndrome, 6 of whom were constipation predominant and 6 of whom were diarrhea predominant, and 8 healthy controls. The procedure was well tolerated by all subjects and did not interfere with sleep or normal activity. In all subjects, the diurnal migrating motor complex cycle was characterized by a brief phase 1 and a prolonged phase 2; this was reversed during sleep when phase 2 was virtually absent. All subjects showed a circadian variation in migrating motor complex propagation velocity, and there was no difference in the patterns of motor activity during sleep between any of the groups. During the day, the duration of postprandial motor activity was shorter in irritable bowel syndrome patients than in controls, and diurnal migrating motor complex intervals were shorter in diarrhea-predominant than in constipation-predominant irritable bowel syndrome. In 11 of 12 inflammatory bowel syndrome patients, episodes of clustered contractions recurring at 0.9-min intervals were noted; these episodes had a mean duration of 46 min and were often associated with transient abdominal pain and discomfort. In both groups of irritable bowel syndrome patients, defecation was significantly (p less than 0.01) prolonged with a greater number of voluntary abdominal contractions (p less than 0.01) than in controls. Prolonged ambulant monitoring of proximal bowel motor activity in subjects who are free to move, eat, and sleep as they choose has, for the first time, clearly defined the striking difference in motility between the sleeping and waking state and shown that abnormalities associated with irritable bowel syndrome are confined to the latter.

Adult↗
PubMed1990

The use of intraluminal strain gauges for recording ambulant small bowel motility.

Perfused-tube manometry has hitherto been the standard technique for recording intraluminal intestinal pressure in humans, but it is unsuitable for ambulant use. The aim of our study was to evaluate the ability of resistive strain gauge transducers attached to a fine catheter to detect pressure change. Simultaneous strain gauge and perfused-tube manometry was performed on six fasting subjects; in four, strain gauge activation was continuous and in two, the transducers were activated in a pulsed mode with data encoded as a pulse train with an approximate frequency of 20 Hz. Eight thousand eight hundred eighty-eight pressure waves were recorded by strain gauge, of which 96% were detected by perfused-tube manometry. There was good agreement in both phases II and III of the migrating motor complex. The amplitude of pressure waves recorded by strain gauge was slightly but significantly greater. A proportion (14-17%) of pressure waves recorded by strain gauge were bifid; this was not seen with the perfused tube. These differences are best explained by the greater sensitivity and more rapid rise time of the strain gauges. There was no loss of fidelity in the pulse-interval recording mode. A seventh subject underwent a continuous 72-h recording with the strain gauge catheter attached to a battery-operated encoder and magnetic tape cassette recorder and was freely ambulant during this period. The procedure was well tolerated and motility patterns could be clearly identified. We conclude that intraluminal strain gauge catheters are suitable for prolonged use in ambulant subjects and produce data that are closely comparable to the data acquired from perfused-tube manometry under laboratory conditions.

Adult↗
PubMed1989

Pressure response of human colon to intraluminal distension.

Pressure response to intraluminal distension was recorded in the ascending and descending colon of six subjects awaiting closure of transverse colostomies to assess and compare compliance in different regions of the human colon. Resistance to distension was significantly greater in the descending colon at intraluminal volumes of 30 ml or greater (P less than 0.01). An equal number of postmortem studies, representing passive connective tissue resistance, demonstrated a similar but more pronounced difference (P less than 0.001), which was maintained after correction for initial intraluminal diameter differences (P less than 0.001). The differences between in vivo and postmortem results indicated an active muscular component in the response of the ascending colon to distension compared with a totally passive distal response. These results support the concept of a functional division in the human colon.

Colon↗
PubMed1989

Effect of feeding on motor activity of canine stomach.

The motor response of the canine stomach to test meals of varied nutrient content and physical state, administered either orally or intraduodenally, was studied. Oral feeding abolished regular contractions in the proximal stomach. There was a simultaneous fall in the proximal gastric baseline force, which slowly recovered to the preprandial level, at which time regular contractions returned. The magnitude and duration of these events varied with the type of meal, as did the distal gastric response, which was characterized by abolition of the fasting motor pattern and establishment of continuous low-amplitude contractions. Duodenal feeding of a nutrient, but not nonnutrient, meal abolished fasting motor activity in both proximal and distal stomach but did not induce either a fall in proximal gastric baseline force or distal gastric contractions. These results suggest that stimulation of duodenal as well as gastric receptors is required to elicit the normal prandial response of both proximal and distal stomach.

Animals↗
PubMed1989

A comparative study of pipothiazine palmitate and fluphenazine decanoate in the maintenance of remission of schizophrenia.

This paper reports a randomized, controlled, partially-blinded, flexible dose, parallel group, comparative study of the efficacy and tolerance of pipothiazine palmitate and fluphenazine decanoate in patients in remission from Schizophrenia over a 28 week period. The results show that pipothiazine palmitate is at least as efficacious and well-tolerated as fluphenazine decanoate in preventing relapses from maintained Schizophrenia.

Adolescent↗
PubMed1987

Development of a platinized platinum/iridium electrode for use in vitro.

Silver/silver chloride (Ag/AgCl) electrodes possess excellent electrical properties for measuring the electrical activity of gastrointestinal smooth muscle but exert toxic effects on this tissue in vitro. We thus developed a platinum electrode for use in vitro, the construction of these electrodes relying upon the formation of a glass-platinum/iridium seal. The platinum/iridium (Pt/Ir) electrodes were platinized using a current density of 0.45 mA mm-2. The electrode impedance at 0.01 Hz showed a minimum with platinization current-time products greater than 500 mA s mm-2. However, deposits in excess of 600 mA s mm-2 were readily removed by mechanical abrasion and proved unsatisfactory. Optimal platinization was obtained with a deposit of platinum-black corresponding to a current-time product of 550 mA s mm-2. Optimally-platinized electrodes (geometric surface area 0.11 mm2) had a stable and reproducible potential with a drift of less than 1 microV min-1 and a lower impedance than optimally chlorided silver electrodes (geometric surface area 0.46 mm2) at frequencies higher than 0.25 Hz. The platinized Pt/Ir electrodes were used to record the electrical activity of gastrointestinal smooth muscle in vitro.

Animals↗
PubMed1987

Modulation of human upper gastrointestinal motility by rectal distension.

The effects of rectal distension on upper gastrointestinal motility were investigated in six healthy subjects. On a control day, gastric and duodenal motor activity was recorded for nine hours of fasting and for four hours after a meal, duodeno-caecal transit being assessed in both interdigestive and digestive states. Motor activity and transit were also measured on a test day during which the rectum was distended for one hour during fasting and for one hour postprandially. Control and test days were randomised. During fasting, rectal distension increased the incidence of migrating motor complexes (0.8 +/- 0.3 v 0.5 +/- 0.2 h; p less than 0.01) and reduced the duodenal phase 2 motility index to 66 +/- 45% of that observed on the control day (p less than 0.01). Further, duodeno-caecal transit time was increased by rectal distension (99 +/- 30 v 71 +/- 35 min; p less than 0.05). Postprandially, the period of rectal distension was marked by a reduction in the duodenal motility index to 24 +/- 13% of that observed during the comparable period on the control day (p less than 0.001) and a concomitant increase in duodeno-caecal transit time (113 +/- 22 v 80 +/- 17 min; p less than 0.01). We conclude that upper gastrointestinal motor activity, the effector of luminal transit, may be profoundly influenced by stimulation of distal afferents.

Action Potentials↗
PubMed1987

Gastro-oesophageal reflux and the migrating motor complex.

Distal oesophageal pH and gastroduodenal motor activity were recorded simultaneously throughout nocturnal (23 30-08 30 h) and diurnal (08 30-17 30 h) periods of fasting in seven healthy subjects. At night, episodes of gastro-oesophageal reflux (GOR) accounted for 1.2 +/- 0.7% of recording time. Periods of gastric motor activity, representing the gastric component of the migrating motor complex (MMC), recurred every 78 +/- 31 min during the night and were interspersed with periods of gastric motor quiescence. Nocturnal episodes of GOR during periods of gastric motor activity were of longer duration (p less than 0.001) and more frequent (p less than 0.005) than during periods of gastric motor quiescence. At night, periodic gastric motor activity was thus correlated (p less than 0.001) with an increase in the duration and number of GOR episodes and associated with a 100-fold increase in oesophageal acid exposure. During the day, the gastric component of the MMC, recurring every 131 +/- 64 min, was correlated (p less than 0.02) with an increase in the duration and number of GOR episodes, and a three fold increase in oesophageal acid exposure. Further, 89% of nocturnal, and 83% of diurnal gastric MMCs were temporally associated with episodes of GOR. We conclude that fasting episodes of GOR occur coincidentally with the gastric component of the MMC.

Adult↗
PubMed1987

Effect of the menstrual cycle on gastric emptying.

Gastric emptying of both solid- and liquid-phase markers was assessed in 7 normally-menstruating women who had undergone bilateral Fallopian tube ligations. The women were studied once during the follicular phase of their menstrual cycle and again during the luteal phase. Emptying of the liquid-phase marker was not significantly different during the two phases of the menstrual cycle. However, emptying of the solid-phase marker was significantly slower during the luteal phase of the cycle as compared to the follicular phase. This impairment of gastric emptying of solid was correlated with elevated serum levels of progesterone. This study demonstrates that the rate of gastric emptying of solids may vary with the phases of the menstrual cycle.

Adult↗
PubMed1986

Esophageal motor abnormalities in gastroesophageal reflux and the effects of fundoplication.

Recordings of esophageal manometry obtained from 18 healthy control subjects and 32 patients with gastroesophageal reflux disease both before and after fundoplication were assessed. Preoperatively, the patients had a mean lower esophageal sphincter pressure at rest that was significantly lower (p less than 0.001) than that observed in the control group. The amplitude of peristaltic contractions, elicited by wet swallows, varied along the length of the esophagus. In patients with gastroesophageal reflux disease, the mean amplitudes recorded from the upper, middle, and lower esophagus were significantly lower (p less than 0.001) than those recorded from control subjects. No significant differences were observed between those patients with (53%) and without preoperative endoscopic evidence of esophagitis. After antireflux surgery (modified Nissen fundoplication), the mean amplitude of peristaltic contractions increased significantly (p less than 0.001) at all levels of the esophagus and were not significantly different from control values. This study describes motor abnormalities in the body of the esophagus associated with gastroesophageal reflux disease. These may arise secondary to gastroesophageal reflux inasmuch as they disappear after fundoplication.

Adolescent↗
PubMed1986

Human colonic smooth muscle: electrical and contractile activity in vitro.

Extracellular electrical and contractile activities were recorded in vitro from strips of human colonic smooth muscle obtained at the time of surgery. Serosal electrical activity of longitudinally oriented strips from the taenia and intertaenial region was characterised by continuous oscillation at a frequency of 28 +/- 1/min. Contractions were marked electrically by a series of oscillations upon which spikes were superimposed. The electrical activity recorded from the submucosal surface of circularly oriented strips exhibited oscillations at 24 +/- 4/min, a frequency significantly lower (p less than 0.001) than that recorded from the serosal surface of similar preparations. The contractile force and frequency was dependent upon the part of the colon from which the strip originated; the most powerful contractions were recorded from strips of sigmoid colon. The contractile frequency of circularly oriented strips from the right colon was 6.3 +/- 0.6/min, significantly higher (p less than 0.001) than that of strips from the left colon (3.4 +/- 0.3/min). Stretching these strips caused an increase in contractile frequency to that of the electrical oscillation.

Colon↗
PubMed1986

Human colonic smooth muscle: spontaneous contractile activity and response to stretch.

The length dependence of the spontaneous contractile activity of human colonic muscle was assessed in vitro. Muscle obtained from the right colon was more distensible than that of the left colon. This was true for all muscle layers. Maximum spontaneous active stress was exerted by both circular and longitudinal muscle layers of the right colon at greater degrees of stretch (p less than 0.001) than those of the left colon. The contractile frequency of longitudinally oriented strips increased with length. The contractile frequency of intertaenial longitudinally oriented strips from the right colon was lower (p less than 0.001) than that of strips from the left colon. The contractile frequency of circularly-oriented strips from the right colon (6.25 +/- 0.38 min) was higher (p less than 0.001) than that of strips from the left colon (3.35 +/- 0.35 min). The human colon appears to consist of two distinct areas based on the mechanical behaviour of the smooth muscle during spontaneous contraction.

Colonic Neoplasms↗
PubMed1985

Effect of progesterone on canine colonic smooth muscle.

This study was undertaken to ascertain the effect and mode of action of progesterone on canine colonic smooth muscle in vitro. Circularly orientated strips of smooth muscle exhibited low-amplitude contractions at the slow wave frequency. Longitudinally orientated strips exhibited larger-amplitude contractions that were associated, electrically, with a series of "spikes" superimposed on a high-frequency oscillation in membrane potential. Progesterone reduced the contractile force of both the circularly and longitudinally orientated strips and the contractile frequency of the longitudinally orientated strips in a dose-dependent manner; this inhibitory effect was observed in the presence of tetrodotoxin but not atropine. The stimulatory effects of a high-potassium superfusate were antagonized by progesterone and verapamil, the effect of progesterone being reversed by increasing the calcium concentration of the superfusate. We conclude that progesterone exerts an inhibitory effect on colonic smooth muscle and this may be mediated by changes in the cytoplasmic calcium concentration.

Animals↗
PubMed1985

Organization of fasting and postprandial myoelectric activity in stomach and duodenum of conscious dogs.

In conscious dogs, contractile and myoelectric activity was recorded from force transducers and monopolar electrodes chronically implanted in the serosal surface of the proximal and distal stomach. Periodic activity during fasting was characterized at each site. Proximally, activity fronts consisted of a series of regular large-amplitude contractions, without correlated myoelectric changes, occurring at 50-s intervals. The distal activity front comprised a series of bursts of two to three contractions 11 s apart, with each burst in phase with a proximal contraction. Only during the burst sequence was each electrical slow wave associated with a spike burst (1:1 phase locking). In contrast, 1:1 phase locking characterized the electrical correlates of the duodenal activity front. Oral feeding abolished periodic activity for at least 3 h. Postprandially, the proximal stomach remained electrically silent; in the duodenum spike bursts were intermittently associated with regular slow waves, but in the distal stomach regular low-amplitude contractions were characterized electrically by 1:1 phase-locked spike bursts and slow waves. These observations suggest that the proximal stomach regulates the canine fasting activity front and require modification of the concept that 1:1 phase locking is a necessary condition of the activity front.

Action Potentials↗