J Hellemans

The interdigestive motor complex of normal subjects and patients with bacterial overgrowth of the small intestine.

Intraluminal pressures were measured in the gastric antrum and at different levels of the upper small intestine in 18 normal subjects to investigate whether or not the interdigestive motor complex, identified in several animal species, occurs in man and, if so, to determine its characteristics. In all normal subjects, the activity front of the interdigestive motor complex was readily identified as an uninterrupted burst of rhythmic contraction waves that progressed down the intestine and that was followed by a period of quiescence. Quantitative analysis of various parameters of the complex and simultaneous radiological and manometrical observations revealed that it resembled closely the canine interdigestive motor complex. To test the hypothesis that disorders of this motor complex may lead to bacterial overgrowth in the small intestine, similar studies were performed in 18 patients with a positive (14)CO(2) bile acid breath test and in an additional control group of 9 patients with a normal (14)CO(2) breath test. All but five patients had normal interdigestive motor complexes. The five patients in whom the motor complex was absent or greatly disordered had bacterial overgrowth as evidenced by (14)CO(2) bile acid breath tests before and after antibiotics. These studies establish the presence and define the characteristics of the normal interdigestive motor complex in man. They also suggest that bacterial overgrowth may be due to a specific motility disorder i.e., complete or almost complete absence of the interdigestive motor complex.

Motilin and the interdigestive migrating motor complex in man.

In order to assess the possible role of the new candidate gut hormone, motilin, in cantrolling the interdigestive migrating motor complex (MMC) in man, 14 normal subjects were studied after an overnight fast by means of three pressure-recording catheters with orifices 25 cm apart in the upper small intestine. The typical aboral progressing bursts of pressure waves occurred at a mean interval of 137 minutes and were preceded by a peak motilin level 25 pmol/liter higher than the lowest level in the postactivity-front quiescent period. To study the effect of exogenous motilin, an infusion of pure porcine motilin at various dose levels was given to 16 normal volunteers shortly after the onset of the phase I quiescent period. Motilin infusion induced an activity front in 12 of the 16 subjects. The mean activity front interval was reduced to 46 min (P<0.001). This effect could be obtained tained even at the low dose level of 0.4 pmol/kg/min, which produced an increase in plasma motilin level of only 57 pmol/liter. These data suggest that a cyclic rise in plasma motilin levels is one of the factors involved in the production of the activity front of the migrating motor complex in man.

Pancreatic polypeptide is not involved in the regulation of the migrating motor complex in man

The role of pancreatic polypeptide (PP) and motilin in the regulation of the migrating motor complex (MMC) was studied in normal subjects. Both plasma motilin and PP levels changed cyclically in the fasted state and were highest in the late phase II period preceding the activity front in the duodenum. A continental breakfast invariably disrupted the MMC and induced a fed pattern of motility. After the meal plasma motilin levels decreased whereas PP levels rose significantly. Infusion of pure porcine motilin during the fasted state induced an activity front and a rise in plasma PP levels. Infusion of bovine PP in doses producing plasma PP levels above the postprandial values neither induced an activity front nor prevented its occurrence. During PP infusion, however, plasma motilin levels were low, although the activity front was not inhibited. PP seems to have no clear role in the regulation of the motor component of the MMC of man. The role of motilin in the production of the activity front of the MMC is discussed.

The impact of concept mapping and visualization on the learning of secondary school chemistry students

The aim of this study was to examine whether the construction of integrated knowledge structures by students can be stimulated by concept mapping and by better visualization of concepts and their interrelationships. The investigation was carried out in regular teaching settings: chemistry courses in secondary schools in Flanders, in the domain of electrochemistry. A significant positive effect of extra attention to visualization on the learning achievement of students was found. However, significant effects of concept mapping as an instruction method could not be detected under the given research conditions.

Peristalsis in smooth-muscle esophagus after transection and bolus deviation

The importance of the continuity of the muscle coat and of the presence of an intraluminal bolus for the peristaltic performance of the Rhesus monkey esophagus was studied. Transection and reanastomosis with muscle-to-muscle contact in the striated muscle part of the esophagus did not interfere with the progression of primary peristaltic contractions. However, when the transection with reanastomosis was performed in the smooth muscle part of the gullet the peristaltic progression of the deglutitive contraction waves in the segment below the transection was affected. After deviation of the swallowed bolus either in the cervical striated esophagus or in the smooth muscle part of the thoracic esophagus, primary peristaltic contractions were seen to progress over the entire length of the gullet; however, in the thoracic esophagus the presence of a bolus facilitated the peristaltic progression of primary waves. These studies also indicate that the extramural vagal innervation is involved in secondary peristaltic contractions of the smooth muscle esophagus.

Electromyographic studies on canine esophageal motility

T hE ELECTRICAL activity of the esophagus is an almost unexplored field of investigation. Mucosal surface electrodes have been used to record the electrical activity of deglutition. 1, 2 A slow wave has been described which develops almost simultaneously with the deglutitive pressure complex. The physiologic significance of this wave is uncertain. 3 In-vitro studies on strips of longitudinal muscle from the lower 2 cm. of the cat esophagus indicate that spike poten~tials accompany slow waves during contraction. 4 Inouye 5 studied the electrical activity of the dog esophagus under general anesthesia. The esophageal deglutitive activity could not be studied in these experimental conditions. After vagotomy, abnormal action potentials were observed, i.e., sharp positive waves and fibrillation potentials. Detailed reports of in-vivo studies using an adequate method of recording have not been published. The relationship of electrical activity, intraluminal pressure, and movements of material in the dog esophagus was studied in Codes laboratory. The preliminary report#, 7 indicate that a peristaltic contraction results in a fixed sequence of events: the first is movement of the barium into the study site and the second is a burst of fast electrical potentials, which is immediately followed by a sharp increase in intraluminal pressure. It seems reasonable to assume that the recording of the deglutitive electrical activity of the esophagus may give important information on both the normal and the disturbed esophageal motility. The purposes of this study were: (1) to analyze the electrical activity which accompanies the peristaltic contraction in the normal esophagus and (2) to investigate the mechanism underlying the high resting pressure in the gastroesophageal sphincter and to study the mechanism of its specific deglutitive response.

Antihypertensive therapy in patients above age 60 with systolic hypertension. A progress report of the European Working Party on High Blood Pressure in the Elderly (EWPHE)

1. Although systolic blood pressure elevation is responsible for increased incidence of cardiovascular accidents in old people, the preventive benefit of lowering systolic hypertension in elderly has not been confirmed. 2. A double blind study comparing the effects of a placebo and of an active regimen (hydrochlorothiazide-triamterene with or without methyldopa) in people over 60 years with isolated systolic hypertension has been undertaken by the European Working Party on High blood pressure in the Elderly (EWPHE). 3. The actively treated group shows a lowered sitting blood pressure (-15/6 mm Hg), a mild increase of serum creatine, serum uric acid and blood glucose and a mild decrease of serum potassium after two years of treatment when compared to the spontaneous changes observed in the placebo treated group. 4. The study is continuing to evaluate if the blood pressure reduction prevents or reduces the incidence of cardiovascular accidents, although some biochemical changes were provoked by the treatment.

Antihypertensive Therapy in Elderly Patients

A study protocol for a double-blind randomised control trial of hypotensive treatment in elderly hypertensive patients has been tested in a number of pilot centres throughout Europe. It was shown that this study is possible from the logistic point of view. In these elderly patients, hydrochlorothiazide + triamterene treatment with or without methyldopa, maintained a significant hypotensive effect in the absence of major electrolyte disturbances. The initiation of hypotensive therapy did not provoke an excess of cardiovascular complications. The influence of hypotensive therapy on the general well-being and on the morbidity and the mortality of elderly patients with high blood pressure, is thereby being assessed. The study will continue for 5 years and other centres are invited to join.

A method for the analysis of intestinal motility records

T h e quali tat ive analysis has been usually carried out by dividing the waves of intestinal contraction into T y p e I and Type I I I . 1, 2 Type I designates simple monophasic waves with an ampl i tude of 3-75 cm. of water, and a dura t ion of 2.5-7.5 sec. Type I I I waves are complex, consisting of an elevation of the base-line pressure, with or wi thout superimposed Type I waves. Th is method of analysis was introduced for moti l i ty records made by means of a balloon system. In t ra lumina l pressure measurements using open-tip catheters did not always permit such a distinction. 3 Tex te r and associates classify the intra luminal pressure waves as Types A (phasic) and B (tonic), T y p e A having a dura t ion of less than 30 sec., and T y p e B, more than 30 sec. Fink 4 confirms the existence of Types I and I I I waves. According to Besan~on, this distinction is not essential. 5 T h e problem may remain unsettled until more is known about the physiological significance and function of these intraluminal pressure changes. Electromyographic studies suggest there is but one basic type of intestinal contraction.~ T h e elevation of the base-line pressure of the T y p e I I I wave might be due to the fact that, at times, the annular contractions originate so close to one another that they are recorded by the same open-t ip catheter. I t is also possible that, dur ing a T y p e I I I wave, the contractions extend over a larger intestinal segment or have a longer durat ion. 6

Antihypertensive therapy in patients above age 60 years. Eighth Interim Report of the European Working Party on High Blood Pressure in the Elderly (EWPHE)

SummarySeven hundred and ninety-two hypertensive patients above the age of 60 years have entered the double-blind multicentre trial of the European Working Party on High Blood Pressure in the Elderly (EWPHE). Half were treated with I capsule daily containing 2.5 mg hydrochlorothiazide and 50 mg triamterene and half were given placebo. If blood pressure control was not adequate in those receiving active treatment, a second capsule was given and, if necessary, up to 2 g methyl-dopa/day. No significant differences between the groups were present prior to randomization. A significant blood pressure difference of 20/8 mmHg was obtained between the groups and maintained during 5 years of follow-up. No major disturbances in serum potassium or serum sodium were noted. On the other hand. during the initial phase an increase in serum creatinine and serum uric acid was noted in the actively-treated group which was maintained during the later years. This increase in serum creatinine was related to the decrease in sit...