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Biomedical subjects

L Lundell

Publications and source records attributed to L Lundell.

At least 109 records · Page 6Linked to original sources

Acid suppression in the long-term treatment of peptic stricture and Barrett's oesophagus.

Peptic stricture and Barrett's oesophagus are not only the major, but also the most common, complications of gastro-oesophageal reflux disease. The clinical problems that these manifestations present are highly significant, and in patients with peptic stricture the resultant dysphagia can be a major disability that causes nutritional problems. Dilation of a stricture exposes the patient to a small, but significant, risk of oesophageal perforation. Barrett's oesophagus per se rarely causes morbidity, but carries a significant risk of developing oesophageal carcinoma, with its attendant morbidity and mortality. Successful anti-reflux surgery for peptic stricture and Barrett's oesophagus effectively abolishes pathological oesophageal acid exposure and provides the best indicator of the potential benefits that may be obtained from treatment with acid-inhibitory drugs. The reported experience clearly indicates that successful anti-reflux surgery results in resolution of peptic stricture following initial dilation, concomitant with persistent control of oesophageal acid exposure. In patients with Barrett's oesophagus, healing of oesophagitis is well documented after successful surgery, but it is unclear whether the Barrett's epithelium progresses or regresses significantly in all but a minority of patients. It is now established that acid pump inhibition can reduce pathological oesophageal acid exposure as effectively as successful anti-reflux surgery. In a minority of patients, however, omeprazole, 40 or 60 mg daily, divided into two doses, is necessary to achieve this effect. This is particularly true for patients with the more severe forms of disease, in whom peptic stricture and Barrett's oesophagus are most prevalent. Results indicate that peptic stricture can resolve during effective gastric acid inhibition with omeprazole, and results from controlled trials on the management of these patients with omeprazole are awaited. Similarly, there are reports of regression of Barrett's oesophagus during omeprazole therapy, but the completeness and predictability of any such effect have not yet been adequately evaluated. There is sufficient experience from long-term omeprazole treatment of gastro-oesophageal reflux disease to indicate that maintenance of a satisfactory response of peptic stricture or Barrett's oesophagus depends upon continued effective gastric acid inhibition.

Barrett Esophagus↗

Partial gastric corpectomy results in hypergastrinemia and development of gastric enterochromaffinlike-cell carcinoids in the rat.

Studies in the rat have shown that partial gastric corpectomy, in which about 75% of the acid-producing oxyntic mucosa was removed, leads to markedly reduced acid secretion and a feedback increase in the plasma gastrin levels. Ten weeks after operation, the gastric enterochromaffin (ECL)-like cell density in the remaining part of the oxyntic mucosa had increased significantly. In the present study, the effects on the gastric ECL cells of lifelong persistent hypergastrinemia induced by partial (75%) corpectomy have been investigated. Seventy-five partially corpectomized rats and 40 control rats were investigated for plasma gastrin and oxyntic mucosal changes in a 124-week study. The partially corpectomized rats showed increased plasma gastrin levels after the operation; the mean increase compared with the controls was almost 10-fold during the entire study. The remaining oxyntic mucosa of the partially corpectomized rats differed from that of control rats in two respects, showing first general hypertrophy and second a marked hyperplasia of argyrophil ECL cells. The degree and incidence of these changes increased towards the end of the study, i.e., in the aging rats. An age-related increase in ECL-cell density occurred spontaneously also in the control rats but to a lesser extent than in the partially corpectomized group. ECL-cell carcinoids were found in the oxyntic mucosa of 26 of the 75 partially corpectomized rats. The first carcinoid was found 78 weeks after the beginning of the study. Six rats with carcinoids (23%) were found before week 104 (2 years) and the remainder, 20 (77%), were discovered later. No carcinoid tumor was found in the control rats. It is concluded that lifelong hypergastrinemia induced by partial corpectomy leads to the development of ECL-cell carcinoids in the oxyntic mucosa of some rats towards the end of their life span. This observation strongly supports the hypothesis that the gastric ECL-cell carcinoids found in rats treated with antisecretory drugs are caused by long-standing hypergastrinemia developing secondary to inhibition of gastric acid secretion.

Animals↗

Effects of some gastrointestinal peptides on isolated human and rabbit gastric glands.

The isolated gastric gland preparation, with aminopyrine accumulation as an index of the parietal cell response, has been used to study the effects of somatostatin (S-14), gastrin-releasing peptide (GRP), cholecystokinin (CCK-8), vasoactive intestinal peptide (VIP), and peptide YY (PYY) on the in vitro acid secretion in human and rabbit oxyntic mucosa. Somatostatin was able to inhibit the parietal cell response to histamine in both human and rabbit isolated gastric glands (maximal inhibition, 22% and 34%, respectively) but failed to inhibit the parietal cell response to db-cAMP. However, other peptides capable of inhibiting gastric acid secretion in vivo, such as CCK, VIP, and PYY, were unable to induce any inhibition of the parietal cell response to db-cAMP or histamine in the isolated gastric gland preparation irrespective of the species studied. GRP was not able to induce a parietal cell response, a finding that is in accord with the assumption that the stimulatory effect of GRP on gastric acid secretion in vivo is by releasing gastrin from antral G-cells.

Animals↗

Factors influencing the release of cholecystokinin induced by gastrin-releasing peptide in man.

We have studied the basal release of cholecystokinin (CCK) and the CCK response to gastrin-releasing peptide (GRP) in man. GRP infusion was followed by a substantial and immediate release of CCK. Pancreatico-duodenectomy or antrectomy with or without duodenal exclusion or antrectomy with truncal vagotomy did not significantly change the basal release of CCK or the GRP-induced CCK release. These results indicate that both basal and GRP-induced release of CCK predominantly originate from the small intestine below the duodenum and the upper part of the jejunum and is unchanged by duodenal exclusion and vagal denervation of the small intestine.

Cholecystokinin↗

Inhibition of gastrin release induced by fundic distension. Evidence of a defective inhibition in duodenal ulcer patients.

The serum gastrin response to an infusion of gastrin-releasing peptide (GRP), with or without simultaneous fundic distension, was studied in healthy volunteers and in patients with duodenal ulcer disease before and after a complete proximal gastric vagotomy (PGV). We also studied the effect of fundic distension alone on gastrin release and intraluminal gastric pressure in healthy volunteers and in patients after PGV. We observed an increased intraluminal pressure in patients after PGV compared with healthy subjects. During fundic distension with 600 ml of air no significant increase in gastrin values was observed in healthy subjects or in duodenal ulcer patients. In healthy subjects fundic distension significantly inhibited the gastrin response to the higher dose of GRP. This inhibitory effect exerted by fundic distension was counteracted by cholinergic blockade. In contrast, fundic distension did not alter the gastrin response to GRP in duodenal ulcer patients, suggesting a defective inhibitory mechanism in duodenal ulcer patients. After PGV, GRP infusion resulted in an enhanced gastrin response, and fundic distension seemed to facilitate the gastrin-stimulatory effect of GRP. This supports the concept of a vagally dependent inhibitory oxyntopyloric mechanism and that fundic distension can elicit both inhibitory and stimulatory secretory mechanisms.

Adult↗

Prevention of relapse of reflux esophagitis after endoscopic healing: the efficacy and safety of omeprazole compared with ranitidine.

Ninety-eight patients with erosive and/or ulcerative esophagitis unhealed after at least 3 months' treatment with standard doses of cimetidine (greater than or equal to 1200 mg daily) or ranitidine (greater than or equal to 300 mg daily) were primarily included in an acute healing phase study, and 51 were allocated to 40 mg omeprazole once daily and 47 to 300 mg ranitidine twice daily. After 12 weeks of treatment, 46 (90%) patients given omeprazole were healed, compared with 22 (47%) allocated to ranitidine. Healed patients were then given maintenance treatment with either 20 mg omeprazole once daily or 150 mg ranitidine twice daily for 12 months. Plasma gastrin was determined and gastric mucosal biopsy specimens were obtained during the entire study to assess the structure of the exocrine and endocrine cell populations of the oxyntic mucosa. Sixty-seven per cent of the total number of patients randomized to omeprazole were maintained in clinical and endoscopic remission throughout the 12-month study period as compared with only 10% among those given ranitidine (p less than 0.0001). After 4 weeks of omeprazole treatment basal gastrin levels were slightly increased, with a 95% confidence interval for the change of from 8.6 to 16.9 pmol/l. No further increase in basal gastrin levels was observed during the ensuing study months. No significant histopathologic lesion was found in the oxyntic gland mucosa. In conclusion, omeprazole was far superior to ranitidine in preventing recurrence, a goal achieved without adverse events and significant abnormalities in the oxyntic mucosal exocrine or endocrine cells but with a moderate increase in basal gastrin levels.

Adult↗

The role of the antrum and the vagus nerve in the metabolism of histamine in the human gastric mucosa.

The effects of antrectomy and proximal gastric vagotomy on the metabolism of histamine in the human gastric mucosa were studied in the basal state and during pentagastrin stimulation in patients with duodenal or gastric ulcer disease. Mucosal biopsy specimens were taken from the antral and oxyntic gland areas, whereafter histamine content, histidine decarboxylase activity, and histamine methyltransferase activity were simultaneously assayed. Vagotomy was followed by a decrease in the acid secretory capacity and an increase in basal serum gastrin levels. Histamine content of the oxyntic mucosa increased after vagotomy, but the ability of pentagastrin to form new amounts of the amine was impaired. Antrectomy caused a decrease in acid secretion and a fall in gastrin concentrations. Basal histamine content and rate of amine formation in the remaining oxyntic mucosa were unaffected by antrectomy. Antrectomy impaired the ability of pentagastrin to release histamine. Histamine methyltransferase was not affected by pentagastrin, vagotomy, or antrectomy. In conclusion, both antral gastrin and the vagus nerve seem to exert a regulatory influence on the metabolism of histamine in the human oxyntic mucosa. The withdrawal of these factors either causes impaired ability of pentagastrin to release histamine from its storage site or counteracts the ability of pentagastrin to accelerate histamine synthesis.

Analysis of Variance↗

24-hour intragastric acidity and plasma gastrin during long-term treatment with omeprazole or ranitidine in patients with reflux esophagitis.

The reduction in intragastric acidity and the subsequent increase in plasma gastrin were compared during long-term treatment with either omeprazole or ranitidine in 19 patients with erosive reflux esophagitis. The patients received 40 mg omeprazole in the morning or 300 mg ranitidine twice daily. After healing, half the dose was given as maintenance treatment for 1 year. Intragastric acidity and plasma gastrin were measured 24 h before entry and monthly with the high dose and after 1, 6, and 12 months with the low dose. Omeprazole reduced intragastric acidity more effectively than ranitidine (p less than 0.001). This difference in efficacy was more pronounced during the daytime. Plasma gastrin increased more after omeprazole than after ranitidine (p less than 0.01), and both drugs showed a normal postprandial response and approached fasting levels before the next dose. During long-term treatment with 20 mg omeprazole in the morning no progressive alterations were observed in 24-h intragastric acidity or plasma gastrin.

Adult↗

Colonic interposition for reconstruction after resection of cancer in the esophagus and gastroesophageal junction.

In 26 patients with carcinoma of the esophagus or gastroesophageal junction, intestinal interposition was performed in post-resection reconstruction, using left colon in 21 cases, right colon in one and a long jejunal segment in four cases. The tumor involved the gastric cardia in 16 patients with colonic interposition and five underwent palliative resection. Infectious pulmonary and abdominal complications were common. Three patients required reoperation, for empyema, ischemic colonic segment and subphrenic abscess, respectively. Ischemia of the interposed segment occurred in two patients, necessitating removal of the segment in one. There was no anastomotic dehiscence and no tumor in the margins of the resected tissue. The 30-day postoperative mortality was 1/22 and the mean postoperative hospital stay 24 days, with 11 patients discharged directly to their homes. The functional results 6 months postoperatively were favorable in most survivors, and only three complained of dysphagia.

Adenocarcinoma↗

Reservoir function after subtotal or total gastrectomy with or without gastric substitute.

Volume and pressure characteristics as a measure of reservoir function were studied in three patient groups greater than 1 year after gastrectomy for cancer, one group with straight Roux-en-Y esophagojejunostomy, one with an s-shaped gastric substitute after total gastrectomy, and the third group with subtotal gastrectomy. A large latex balloon was introduced into the proximal jejunum, gastric substitute or gastric remnant and then filled with water at a constant, slow rate. The maximal volume capacity was 400 ml at basal pressure 13.9 cmH2O in the remnant after subtotal gastrectomy and 475 ml at 10.4 cm in the gastric substitute, but only 180 ml at basal pressure 40.4 cmH2O in the proximal Roux limb of the straight esophagojejunostomy. Maximal basal pressure and maximal pressure amplitudes throughout the study period were significantly higher in the patients with straight Roux-en-Y esophagojejunostomy. The results suggest that a gastric substitute constructed as an s-shaped pouch is characterized by pressure and volume typical of a low-pressure reservoir, similar to that achieved by leaving the proximal part of the stomach intact.

Adult↗

Somatostatin release induced by gastrin-releasing peptide in man. Effect of proximal gastric vagotomy and cholinergic blockade.

The influence of intragastric pH on the basal release of somatostatin has been studied in healthy controls and in duodenal ulcer patients. In addition the somatostatin response to gastrin-releasing peptide infusion has been evaluated both regarding the effect of intragastric pH and the influence of vagal innervation and muscarinic blockade. No difference was found in basal blood levels, when changing the intraluminal pH, although a slightly higher basal somatostatin concentration was noticed in patients with duodenal ulcer disease. Neither proximal gastric vagotomy nor cholinergic blockade had any effect on basal somatostatin concentrations. GRP infused in stepwise increasing doses from 20 pmol/kg/h to 400 pmol/kg/h induced a small but significant response. This effect of GRP was most evident, when the stomach was perfused with 0.1 M HCl. The small, somatostatin response to GRP infusion was not influenced by vagal denervation of the parietal cell area, neither by cholinergic blockade. Despite the previously observed effects of vagotomy and cholinergic blockade on gastrin release induced by GRP, a corresponding inverse effect on somatostatin is not apparent.

Adult↗

Gastrin-releasing peptide: neuronal distribution and spatial relation to endocrine cells in the human upper gut.

By using immunocytochemical techniques, we have studied the distribution of gastrin releasing peptide (GRP)-containing neurons as well as the spatial relationship between these neurons and the endocrine cells in the human stomach and duodenum. Moderate numbers of immunoreactive fibers were distributed in the smooth muscle and submucosa of the stomach; they were more rare in the duodenal wall. Numerous GRP-containing nerve fibers were found in the oxyntic mucosa, the antral mucosa harboured only few GRP immunoreactive nerve fibers. The mucosa of the proximal duodenum was found to be virtually devoid of such fibers. Only occasionally did we observe signs of a direct contact between GRP-containing nerve fibers and gastrin and somatostatin cells in the antral mucosa. In the oxyntic mucosa GRP-containing nerve fibers sometimes seemed to contact endocrine cells, including somatostatin cells as well as individual parietal cells. In conclusion, although GRP-containing nerve fibers were quite numerous in the wall of the human upper gastro-intestinal (GI)-tract, we observed a lack of intimate spatial relationship between these fibers and endocrine cells in the antral mucosa, suggesting additive mechanisms to a direct innervation of gastrin cells and somatostatin cells by GRP nerve fibers explaining the physiological effects on hormonal release.

Adult↗

Histamine metabolism in human gastric mucosa. Effect of pentagastrin stimulation.

The metabolism of histamine in the human gastric mucosa was studied in the basal state and during pentagastrin stimulation. Studies were made in healthy volunteers and in patients with peptic ulcer disease. Mucosal biopsies were taken from antral and oxyntic gland areas whereupon histamine content, histidine decarboxylase activity, and histamine methyltransferase activity were simultaneously assayed. Histamine content of the oxyntic gland mucosa was decreased as a consequence of pentagastrin administration in all groups studied, and this decrease was numerically largest in patients with duodenal ulcer disease. Pentagastrin induced a significant increase in histidine decarboxylase activity of the oxyntic gland mucosa with the most profound increase seen in patients with duodenal ulcer. The highest rates of histamine formation were present in the oxyntic mucosa of patients with Zollinger-Ellison syndrome. The activity of histamine methyltransferase was the same in all groups studied and was not changed by pentagastrin. In conclusion, pentagastrin administration in humans is followed by a significant mobilization of histamine only from the oxyntic gland mucosa, an effect that is more pronounced in patients with duodenal ulcer disease.

Adult↗

Omeprazole or high-dose ranitidine in the treatment of patients with reflux oesophagitis not responding to 'standard doses' of H2-receptor antagonists.

Ninety-eight patients (26 females), who presented with erosive and/or ulcerative oesophagitis, despite at least a 3-month period of treatment with standard doses of cimetidine (greater than or equal to 1200 mg daily) or ranitidine (greater than or equal to 300 mg daily), were included in a double-blind, randomized trial to compare omeprazole (40 mg o.m.) with a high dose of ranitidine (300 mg b.d.). The treatment was given for 4-12 weeks; endoscopy assessment and laboratory screening were performed on entry to the trial and thereafter every fourth week. Endoscopic healing was defined as complete epithelialization of all macroscopic erosions or ulcers in the squamous epithelium. An 'intention-to-treat' analysis of the clinical data revealed omeprazole to be superior to ranitidine: 63% of those patients who were given omeprazole were healed endoscopically after a 4-week period of treatment, compared with only 17% of those given ranitidine. This difference in healing rate persisted during the 12-week study period (90% vs 47% after 12 weeks; P less than 0.0001). Reflux symptoms were more rapidly and completely relieved with omeprazole: heartburn resolved completely in 86% of patients treated with omeprazole for 4 weeks compared with 32% in the ranitidine group (P less than 0.0001). The mean basal gastrin concentrations increased only in those given omeprazole from 18.9 pmol/L at pre-entry to a mean value of 31.7 pmol/L on the last day of omeprazole administration. In ranitidine-treated patients no significant increase in basal gastrin concentration was observed. Both drugs were well tolerated with few adverse events, which were mainly mild and transient. These results demonstrate the superiority of omeprazole over a high dose of ranitidine in the treatment of resistant reflux oesophagitis.

Adult↗

Histamine containing endocrine cells in the human stomach.

Histamine and chromogranin A-immunoreactive cells were studied in the mucosa of the human stomach. Cells reacting to both histamine and chromogranin A-antibodies (histamine containing endocrine cells), were demonstrated by double immunostaining and found to be restricted to the oxyntic mucosa. Histamine containing cells that did not stain with chromogranin A-antibodies were numerous throughout the stomach. Of the histamine immunoreactive cells in the oxyntic gland area 22% reacted with antibodies against chromogranin A. Histamine containing endocrine cells constituted 44% of the total number of endocrine cells in the oxyntic mucosa. These findings suggest that the histamine containing endocrine cells in the human stomach are identical with the so called enterochromaffin like cells.

Adult↗