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Biomedical subjects

H Forssell

Publications and source records attributed to H Forssell.

At least 55 records · Page 3Linked to original sources
PubMed1988

Reflex sympathetic activation in humans is accompanied by inhibition of gastric HCO3- secretion.

The study was performed to determine whether the sympathetic nervous system contributes to the reflex control of gastric HCO3- secretion in humans. Gastric HCO3- secretion was registered by a computerized technique based on measurements of pH and PCO2 in gastric effluent. To minimize formation of CO2 in the stomach, subjects were pretreated with the H2-receptor blocker ranitidine. Compensations were made for HCO3- of nongastric origin. As indicators of cardiovascular sympathetic activity, we measured heart rate, forearm vascular resistance, and plasma catecholamine concentrations. In one series of experiments, peripheral sympathetic activity was enhanced by the application of a negative pressure around the lower part of the body (lower body negative pressure, LBNP), at a rate sufficient to induce a slight decrease in systemic arterial pressure. In another series of experiments, peripheral sympathetic activity was inhibited by elevation of the legs, a procedure that simulates volume loading by redistributing blood volume toward the central circulation. LBNP at -20 mmHg decreased systolic pressure and pulse pressure and significantly increased heart rate, forearm vascular resistance, and plasma catecholamine levels. All these effects were observed in the first 15-min period of LBNP and were well maintained throughout the 45-min observation period. LBNP also inhibited basal gastric HCO3- secretion rate in seven of eight individuals, but this response was slower in onset with a latency of at least 15 min. Elevation of the legs increased pulse pressure and decreased forearm vascular resistance. Catecholamines were not measured in these experiments. Gastric HCO3- secretion tended to increase, but the magnitude of the response was highly variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Relationship between reduction of gastric acid secretion and plasma gastrin concentration during omeprazole treatment.

We have studied the relationship between reduction of gastric acid secretion and fasting plasma gastrin concentrations during once daily omeprazole treatment. Healthy subjects were given omeprazole for 5 days in daily doses of 5, 10, 20, 40, or 80 mg. Acid secretion and fasting gastrin concentration were measured 6 h (maximal omeprazole effect) and 24 h (minimal omeprazole effect) after the fifth omeprazole dose. Omeprazole in doses lower than 20 mg daily did not suppress pentagastrin-stimulated acid secretion in all subjects 6 h after dosing on the 5th day. Doses of 20-80 mg omeprazole, however, significantly reduced acid secretion 24 h after the fifth dose, the range being 36-76%. A relationship between degree of acid inhibition and fasting gastrin concentration was observed. However, acid secretion needed to be reduced by more than 80% before gastrin levels were clearly affected. This degree of acid inhibition was only achieved 6 h after administration of omeprazole in doses of 20 mg and higher. The inhibitory effect of omeprazole on acid secretion decreased 24 h after dosing. Thus, fasting gastrin concentrations were moderately increased in the beginning and normalized at the end of each 24-h period during treatment with daily doses of 20-80 mg omeprazole.

Adult↗
PubMed1988

A criterion for completeness of vagotomy based on basal and vagally stimulated gastric acid secretion after esophagectomy or proximal gastric vagotomy.

The variation in basal acid secretion was determined in 10 patients after resection of the esophagus, an operation resulting in a total transection of all vagal nerves to the abdomen. After recording basal acid secretion over a 3-h period, a 15-min modified sham feeding procedure was performed, and the acid output was studied for an additional hour. The mean basal acid output +2 SD was 0.27 mmol/15 min. The difference between the highest and lowest recorded 15-min output--that is, the oscillation of basal acid output--was calculated for each patient. The mean oscillation of basal acid output +2 SD was 0.58 mmol/15 min. Vagal stimulation accomplished by sham feeding produced no significant increase in acid output above this level. The variation in basal acid secretion was also investigated in 20 duodenal ulcer patients after proximal gastric vagotomy. These patients were insulin-negative and remained asymptomatic during a 7- to 10-year follow-up study. Shortly after the vagotomy, measurement of basal acid secretion over 3 h showed a mean basal acid output +2 SD of 0.58 mmol/15 min. The mean oscillation of basal acid output +2 SD was 0.66 mmol/15 min. On the basis of the oscillation in basal acid secretion after complete vagotomy we propose a new criterion for completeness of vagotomy, namely a response to physiologic vagal stimulation which does not exceed the lowest basal level by more than 0.6 mmol/15 min.

Adult↗
PubMed1988

Gastric mucosal defence mechanisms: a brief review.

In the stomach several mucosal defence mechanisms protect the stomach against hydrochloric acid and noxious agents. The pre-epithelial protection is made up by the mucus-bicarbonate barrier. Mucus and bicarbonate, secreted by mucus cells, create a pH gradient maintaining the epithelial cell surface at near neutral pH. In humans, secretion of bicarbonate is an active process and is activated by vagal stimulation and fundic distension. Several mechanisms at the epithelial cell level contribute to an intact mucosal barrier. Surfactants in apical cell membranes prevent water-soluble agents in the gastric lumen from reaching and damaging the epithelium. Nonprotein sulphydryls in the epithelium are capable of binding reactive free radicals. Rapid cell turn-over and the process of restitution contribute to an intact epithelial lining. In subepithelial protection, mucosal blood flow is essential in supplying the epithelium with nutrients and oxygen and for disposal of hydrogen ions and noxious agents permeating the mucosa. Prostaglandins may maintain blood flow and prevent vascular endothelial injury caused by ethanol. Several agents have been established as protective for the gastric mucosa. Prostaglandins possess direct cytoprotective actions, whilst sucralfate, aluminium containing antacids, carbenoxolone and bismuth are mild irritants that induce liberation of endogenous prostaglandins of the mucosa.

Antacids↗
PubMed1987

Response to occlusal treatment in headache patients previously treated by mock occlusal adjustment.

Headache patients who had received mock occlusal adjustment and who, after the placebo treatment, were judged to have moderate to severe mandibular dysfunction were offered further treatment. The present study reports the results of occlusal treatment in 19 patients who were willing to undergo further treatment. Statistically significant reduction after occlusal treatment (occlusal adjustment, aided in some cases by temporary use of occlusal splints) was observed in clinical signs (P less than 0.05) and subjective symptoms (P less than 0.01) of mandibular dysfunction and in the frequency of headache (P less than 0.05). The results are complementary to our earlier clinical studies and corroborate the conclusion that improvements after occlusal treatment exceed those after placebo treatment.

Dental Occlusion, Balanced↗
PubMed1987

Effect of fundic distension on gastric bicarbonate secretion in man.

Human gastric mucosa secretes small amounts of bicarbonate into the mucus layer to maintain the pH at the cell surface as close to neutrality as possible. We have measured gastric bicarbonate secretion continuously with a computer-based system, using recordings of pH and PCO2. The formula of Henderson and Hasselbalch was used in the calculations. Graded fundic distension of the stomach with a balloon in six healthy subjects increased the gastric bicarbonate output by 46% (p less than 0.05), 28% (NS), and 84% (p less than 0.05) during 1 h of distension to 150 ml, 300 ml, and 600 ml, respectively. Continuous fundic distension during 2 1/2 h with a volume of 300 ml elicited a response that peaked after 45 min and vanished after 90 min. The rather short duration of gastric bicarbonate secretion response to fundic distension may be due to a fading caused by a volume adaptation or, alternatively, to an activation of inhibitory mechanisms. Seven duodenal ulcer patients who had undergone proximal gastric vagotomy showed virtually the same gastric bicarbonate secretion response to graded fundic distension. The anticholinergic drug benzilonium bromide totally inhibited the gastric bicarbonate response to 30 min of fundic distension to 150 ml, whereas indomethacin did not significantly affect the response to distension. These studies indicate that the gastric bicarbonate response to fundic distension is mainly mediated by short intramural neural cholinergic pathways and is independent of mucosal production of prostaglandins.

Adult↗
PubMed1987

Effect of proximal gastric vagotomy on basal and vagally stimulated gastric bicarbonate secretion in duodenal ulcer patients.

Basal gastric bicarbonate secretion and the response to vagal stimulation accomplished by sham feeding were investigated in duodenal ulcer patients before and after proximal gastric vagotomy. Gastric bicarbonate secretion was measured with a computer-based system, which continuously recorded the pH and PCO2 of the gastric perfusate. Preoperatively, basal bicarbonate secretion was 414 +/- 57 mumol/h (mean +/- SEM, n = 9), and the secretory response to vagal stimulation 691 +/- 83 mumol/h (p less than 0.01). About 2 months after proximal gastric vagotomy the basal gastric bicarbonate secretion was 539 +/- 74 mumol/h, and the response to vagal stimulation 693 +/- 72 mumol/h (p less than 0.01). The basal bicarbonate secretion thus increased by 30% after vagotomy (p less than 0.01) but about 1 year later was not significantly different from the basal preoperative value. In the early postoperative period anticholinergics significantly reduced the enhanced basal bicarbonate secretion to a preoperative level. When tested 1 year after the operation anticholinergics did not affect basal bicarbonate secretion but abolished the response to sham feeding. The findings of the study suggest the existence of cholinergic vagal nerve fibres stimulating human gastric bicarbonate secretion and indicate that inhibitory nerve fibres may modulate gastric bicarbonate secretion.

Adult↗
PubMed1987

Basal and stimulated human gastric bicarbonate secretion.

The mucus-bicarbonate barrier on the gastric mucosa is regarded as a first-line of defence against acid. Both mucus and bicarbonate originate from the mucus cells in the gastric mucosa. Bicarbonate is secreted actively by Cl-/HCO3- exchange at the luminal cell membrane. A computer based system with continuous measurement of pH and PCO2 in a gastric perfusion system was used to determine human gastric bicarbonate secretion. The rate of basal gastric bicarbonate secretion in 24 healthy subjects was 386 +/- 31 mumol/h (mean +/- SEM). The 95% confidence interval for basal bicarbonate output was 103-669 mumol/h. Vagal stimulation by sham feeding increased the bicarbonate output by 63% and instillation of 16,16 dimethyl prostaglandin E2 increased the bicarbonate output by 214%. The response to vagal stimulation was independent of intragastric pH. The sham feeding response was abolished by premedication with anticholinergics. Basal and vagally stimulated bicarbonate secretion was unaffected by prostaglandin biosynthesis blockade.

16,16-Dimethylprostaglandin E2↗
PubMed1987

Antibiotic prophylaxis in high-risk gastric surgery. A prospective, randomized clinical comparison of cefuroxime and doxycycline.

The efficacy of two antibiotics as prophylaxis in high-risk gastric surgery was evaluated in a prospective, randomized trial: 400 mg doxycycline in a single dose (98 patients) was compared with 1.5 g cefuroxime given twice with an 8-hour interval (101 patients). The two groups were comparable in regard to all relevant factors of importance for susceptibility to infection. The incidence of postoperative abdominal infection was 8.2% in the doxycycline group and 7.9% in the cefuroxime group. The most common extraabdominal infectious complications were in the lungs (20% of the patients in both groups). No subgroup of patients was identifiable in which one antibiotic was superior to the other. The efficacy of the two investigated prophylaxis regimens was apparently identical.

Cefuroxime↗
PubMed1987

Studies on gastric bicarbonate secretion in man.

A method for measurement of human basal and stimulated gastric bicarbonate secretion was developed in the present investigation. The mechanisms involved in the regulation of basal, vagus nerve stimulated as well as fundic distension induced bicarbonate secretion were studied. The investigations were performed in healthy subjects and duodenal ulcer patients, the latter group before and/or after a proximal gastric vagotomy operation. Healthy subjects as well as ulcer patients were premedicated with a histamine H2-receptor antagonist and gastric bicarbonate secretion was determined by use of a gastric perfusion system in combination with computerized continuous recordings of pH and PCO2. The contribution of alkaline saliva to the measured gastric bicarbonate secretion was minimized by continuous salivary suction and correction was made for swallowed saliva by measurement of amylase in the gastric aspirate. A high rate of gastric perfusion facilitated the identification of alkaline duodenogastric reflux and also eliminated its influence on the measurement of gastric bicarbonate secretion. Validation of the measuring system by instillation of small amounts of bicarbonate showed a satisfactory correlation between added and recovered bicarbonate in the range of bicarbonate determinations usually recorded. Decreasing intragastric pH to between 3 and 4 converted all secreted bicarbonate into CO2, but did not affect the measured value of bicarbonate secretion. Vagal stimulation accomplished by sham feeding increased gastric bicarbonate secretion in sixteen healthy subjects from 410 +/- 39 mumol/h to 692 +/- 67 mumol/h (mean +/- SEM, p less than 0.001). This response was independent of intragastric pH in the range of 2 to 7. The muscarinic receptor antagonist, benzilonium bromide, almost abolished the sham feeding response while indomethacin left it nearly unchanged. Nine duodenal ulcer patients had identical basal and vagally stimulated bicarbonate output as healthy subjects. Two months after proximal gastric vagotomy, the basal bicarbonate secretion was significantly increased, whereas the output in response to sham feeding was unaltered. In the early postoperative period, anticholinergics reduced the enhanced basal bicarbonate secretion to a preoperative level. In six healthy subjects, graded fundic distension with a balloon to volumes of 150 ml, 300 ml and 600 ml, each distension period lasting 60 minutes, increased the bicarbonate secretion by 46% (p less than 0.05), 28% (NS) and 84% (p less than 0.05), respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

16,16-Dimethylprostaglandin E2↗
PubMed1987

Measurement of pouch volume and stoma diameter after gastroplasty.

A balloon technique has been developed for measurement of the pouch volume and stoma diameter after gastroplasty. Twenty-seven patients prospectively included in a randomized study of two types of gastroplasty operation have been investigated 6 months postoperatively. During the operation the proximal pouch was calibrated to be about 40 ml and the stoma diameter to 11 min. Six months after the operation the patients had on average reduced weight by 29 kg. Using the balloon technique, the stoma diameter was 12 +/- 1.6 (s.e.m.) mm and the pouch volume 80 +/- 11.0 ml. There was a significant correlation between the stoma diameter and weight reduction during the first 6 months postoperatively (P less than 0.01). The relationship between the stoma diameter and weight reduction followed best an exponential equation. No correlation was found between the pouch volume and weight reduction. The presented technique for measurement of pouch volume and stoma diameter after gastroplasty may be an important tool to evaluate the influence of various factors on the long-term results of surgical treatment for morbid obesity.

Body Weight↗
PubMed1986

Effect of occlusal adjustment on mandibular dysfunction. A double-blind study.

A group of headache patients who also had many signs and symptoms of mandibular dysfunction were randomly assigned to treatment and placebo groups. All 48 patients in the treatment group received occlusal adjustment and 19 of them also splint therapy. In the placebo group all 43 patients received mock adjustment. The changes in symptoms and signs of mandibular dysfunction were evaluated after 8 months in the treatment group and after 4 months in the placebo group, in a double-blind design. Placebo treatment and real treatment were equally effective in relieving symptoms of mandibular dysfunction, but there was significantly more reduction in signs of dysfunction in the treatment group than in the placebo group. When tested statistically, this reduction appeared to be independent of the use of splints as an aid to treatment. It can be concluded that the elimination of occlusal disturbances was an effective treatment for mandibular dysfunction.

Adolescent↗
PubMed1985

Vagal stimulation of human gastric bicarbonate secretion.

Gastric bicarbonate secretion in humans was determined in vivo by using a gastric perfusion-aspiration system. A computer calculated the bicarbonate concentration every 30 s throughout the experiment from measurements of the pH and PCO2 in the aspirate. The total bicarbonate concentration was calculated according to the formula of Henderson and Hasselbalch as the sum of free bicarbonate plus the CO2 that was formed during reaction of bicarbonate with hydrogen ions. In 16 subjects basal gastric bicarbonate secretion was 410 +/- 39 mumol/h (mean +/- SEM). After sham feeding using the chew and spit technique to achieve physiologic vagal activation, the gastric bicarbonate secretion rate increased to 692 +/- 67 mumol/h (p less than 0.001). This response of bicarbonate secretion rate to vagal stimulation was independent of the intragastric pH (range 2-7). In 6 subjects the sham-feeding response was almost abolished (88% inhibition) by the anticholinergic drug benzilonium bromide, however, it was unaffected by premedication with indomethacin. The findings demonstrate that the increase in gastric bicarbonate secretion during the cephalic phase of gastric secretion occurs parallel to the increase in acid secretion. It may therefore be regarded as a physiologic response to reinforce the protective mucus-bicarbonate barrier. The response to vagal stimulation seems to be mediated by a muscarinic transmitter and to be independent of intragastric pH and endogenous prostaglandins.

Adult↗