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Biomedical subjects

Y J Kingma

Publications and source records attributed to Y J Kingma.

At least 19 recordsLinked to original sources
PubMed1991

An active feedback system for isotonic studies of smooth muscle.

A feedback system used to perform isotonic studies of smooth muscle is presented. This system is capable of applying a constant force to muscle samples regardless of their contractile activities. The force applied to the tissue is controlled using a proportional integral control system that drives a linear motor. The device is integrated into a sucrose gap tissue bath apparatus where measurements of displacement and electrical activity are also possible. The frequency of canine colonic smooth-muscle electrical oscillations is positively related to applied force.

Animals↗
PubMed1991

Can transcutaneous recordings detect gastric electrical abnormalities?

The ability of transcutaneous recordings of gastric electrical activity to detect gastric electrical abnormalities was determined by simultaneous measurements of gastric electrical activity with surgically implanted serosal electrodes and cutaneous electrodes in six patients undergoing abdominal operations. Transient abnormalities in gastric electrical activity were seen in five of the six patients during the postoperative period. Recognition of normal gastric electrical activity by visual analysis was possible 67% of the time and with computer analysis 95% of the time. Ninety four per cent of abnormalities in frequency were detected by visual analysis and 93.7% by computer analysis. Abnormalities involving a loss of coupling, however, were not recognised by transcutaneous recordings. Transcutaneous recordings of gastric electrical activity assessed by computer analysis can usually recognise normal gastric electrical activity and tachygastria. Current techniques, however, are unable to detect abnormalities in electrical coupling.

Diagnosis, Computer-Assisted↗
PubMed1991

Electrical activity of canine gallbladder.

Our aims were to describe the myoelectrical activity in the single very thin layer of muscle of the canine gallbladder. The study was performed on 22 freshly removed canine gallbladders. Electrical activity was studied by the single sucrose-gap method and contractility of the tissue was measured simultaneously using a force transducer. The strips (15 x 1 mm) from different regions of gallbladder (fundus, corpus, neck) were cut in longitudinal, circular and oblique axes. The sucrose-gap apparatus together with connecting tubes, solutions and electrodes were kept at 37 degrees C and the initial tension applied to the tissue was set to 1 g. In 82.7% of recordings, spontaneous myoelectrical activity consisted of regular rhythmic changes in membrane potential similar to slow waves recorded in intestinal tissue. The overall mean frequency was 11.4 +/- 5.2 (mean +/- SD) cycles per min: 11.1 +/- 4.4 cycles per min in fundus, 11.9 +/- 6.2 cycles per min in corpus and 10.8 +/- 3.8 cycles per min in the neck of the gallbladder. In 84.2% of cases electrical activity correlated with mechanical activity and preceded it. No significant differences were seen between the electrical patterns in strips with different orientations or from the different regions of the gallbladder.

Animals↗
PubMed1990

Simultaneous measurement of electrical activity from two colonic smooth muscle layers using a dual sucrose gap apparatus.

An apparatus using the sucrose gap technique is presented. With this apparatus simultaneous measurements of contractile and intracellular electrical activity from the two smooth muscle layers of the colon are made. An "L-shaped" muscle preparation consisting of a leg from the circular muscle layer and a leg from the longitudinal muscle layer is used. A theoretical discussion of the device's operation is presented. Finally, experimental results that validate the theory are included.

Animals↗
PubMed1990

Electrical and mechanical interactions between the muscle layers of canine proximal colon.

Electrical and mechanical interactions between the two smooth muscle layers of canine colon have been studied using a dual sucrose gap apparatus. Muscle samples were dissected into an L-shape, with one leg cut in the circular direction and the other cut in the longitudinal direction. Longitudinal muscle was removed from the circular leg and circular muscle was removed from the longitudinal leg. The bend of the L contained both layers. The activity of the two layers was studied simultaneously under basal conditions, after stimulation by neostigmine and carbachol, and in the presence of tetrodotoxin. Interactions were more common after stimulation and were marked by modification of one layer's mechanical and electrical activity during increased activity in the other layer. Two patterns were commonly observed. First, during a burst of membrane potential oscillations and spike potentials in the longitudinal layer, slow waves in the circular layer developed spike potentials and some slow waves were also prolonged. Second, during a slow-wave cycle in the circular layer, the amplitude of membrane potential oscillations in the longitudinal layer was increased with an associated increase in the incidence of spike potentials. These interactions were associated with contractions of increased strength, which were similar in both layers. All interactions continued after nerve-conduction blockade by tetrodotoxin.

Animals↗
PubMed1989

The electrogastrogram and its analysis.

In recent years interest in the electrogastrogram, the EGG, has manifested itself in an increasing number of articles. In this review a brief exposition of the EGG phenomenon is made and the more prominent methods of signal analysis relevant to the EGG are presented and discussed.

Amplifiers, Electronic↗
PubMed1988

Colonic and anorectal motility in young women with severe idiopathic constipation.

Forty-four severely constipated women and 16 (8 female, 8 male) asymptomatic volunteers underwent assessment of colon function by (a) clinical examination, (b) rectosigmoid intraluminal pressure recording, (c) colonic transit utilizing radiopaque markers, (d) anorectal manometry, and (e) rectosigmoid electrical activity. Constipated patients were characterized by (a) a greater volume and pressure of rectal distention required for both sensation and sphincter relaxation, (b) diminished basal and postmorphine motility indices only in the distal rectum, (c) delayed transit, and (d) an empty rectum when severely constipated. A neural abnormality affecting afferent nerves may be present in the rectum of female patients with severe idiopathic constipation. Delivery of stool to the rectum is impaired in these patients.

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↗
PubMed1979

In vitro electrical activity in canine colon.

In vitro slow wave activity was studied in strips of right and left canine colon with silver/silver chloride electrodes. Using visual and computer analysis, slow wave frequency and coupling was assessed between different recording sites and the effect of a cholinergic agonist on coupling and frequency was determined. A regular slow wave was always found to be present. Frequency in the left colon was slightly higher than in the right with a slight decline noted with time. Spike activity was rarely seen in unstimulated specimens. Administration of a cholinergic agonist produced a decrease in frequency with no improvement in coupling. Coupling was usually better in a circular than in a longitudinal direction. It was concluded that if electrical activity is important in the control of colon contractions, it is more likely to be involved in the control of segmentation than in propagated contractions.

Action Potentials↗
PubMed1979

Electrical and mechanical activity in the ex vivo perfused total canine colon.

Electrical and mechanical activity were studied in the ex vivo total canine colon, supported in a perfusion chamber by a supporting dog. Regular electrical activity could be recognized visually in 50--70% of the records. The frequency of this activity was in the range of 7--10/min. Fourier analysis also revealed dominant frequencies in this range. Two types of mechanical activity were observed. The first consisted of small amplitude repetitive contractions, which appeared both during quiescent periods and during vigorous contractions. The frequency of this rippling, when periodic, usually approximated that of the electrical activity. The second type consisted of large amplitude prolonged (30--135 sec) contractions. Without stimulation, the large amplitude contractions were asynchronous and not propagated. Following neostigmine, however, the large amplitude contractions were always propagated aborally and were usually associated with evacuation of the colon. The rippling contractions had a frequency similar to the regular electrical activity and are probably under their control. The large amplitude, prolonged duration contractions are unlikely, however, to be solely under myogenic control.

Animals↗
PubMed1978

Provisional model for propagation of electrical activity in upper urinary tract.

A theory on the function of the renal pelvis as a pacemaker for ureteral peristalsis is given. The bioengineering "black box" approach is used to describe peristaltic behavior monitored at the ureter and thr renal pelvis, by both peristaltic pressure and electromyographic methods. The model provides a stimulus to further thought on the nature and significance of electrical activity in the upper urinary tract.

Electromyography↗