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589 results on '"Waldum, Helge L."'

3. Hermod Petersen

Author

Dybdahl, Jan H., primary, Kleveland, Per Martin, primary, Waldum, Helge L., primary, Brenna, Eiliv, primary, and Sandvik, Arne K., primary

Published
2023
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18. Ciprofibrate stimulates the gastrin-producing cell by acting luminally on antral PPAR-[alpha]

Author

Martinsen, Tom C., Bakke, Ingunn, Chen, Duan, Sandvik, Arne K., Zahlsen, Kolbjorn, Aamo, Trond, and Waldum, Helge L.

Subjects
Fibric acids -- Usage, Gastric bypass -- Research, Gastrin -- Research, Biological sciences
Abstract

The lipid-lowering drug ciprofibrate stimulates gastrin-producing cells in the rat stomach without lowering gastric acidity. Although suggested to be a luminal action on antral peroxisome proliferator-activated receptor-[alpha] (PPAR-[alpha]), the mechanism is still not fully elucidated. Gastric bypass was surgically prepared in male Sprague-Dawley rats. Gastric-bypassed and shamoperated rats were either given ciprofibrate (50 mg * [kg.sup.-1] * [day.sup.-1] in methocel) or vehicle alone for 7 wk. PPAR-[alpha] knockout (KO) and wild-type (WT) mice were either given ciprofibrate (500 mg * [kg.sup.-1] * [day.sup.-1] in methocel) or vehicle alone for 2 wk. The concentration of gastrin in blood was analyzed. Antral G cell density and gastrin mRNA abundance were determined by using immunostaining and Northern blot analysis. Ciprofibrate did not raise plasma gastrin or G cell density in gastric-bypassed rats, although the gastrin mRNA level was slightly increased. In contrast, ciprofibrate induced hypergastrinemia, a 50% increase in G cell density, and a threefold increase in gastrin mRNA in sham-operated rats. In PPAR-[alpha] KO mice, ciprofibrate did not raise G cell density or the gastrin mRNA level. The serum gastrin level was reduced by ciprofibrate. In WT mice, ciprofibrate induced hypergastrinemia, a doubling of G cell density, and a threefold increase in gastrin mRNA. Comparing animals dosed with vehicle only, PPAR-[alpha] KO mice had higher serum gastrin concentration than WT mice. We conclude that the main effects of ciprofibrate on G cells are mediated from the antrum lumen, and the mechanism is dependent on PPAR-[alpha]. The results indicate that PPAR-[alpha] may have a role in the physiological regulation of gastrin release. peroxisome proliferator-activated receptor-[alpha]; hypergastrinemia; gastric bypass; peroxisome proliferator-activated receptor-[alpha] knockout mice

Published
2005

27. Trichobezoars in praomys (mastomys) natalensis

Author

Hanssen, Ingolf and Waldum, Helge L

Subjects
digestive, oral, and skin physiology
Abstract

We have in a rat model studied the role of gastric neuroendocrine cells in the regulation of gastric function and growth and given indication for an important role of these cells in physiology and human carcinogenesis. Because of the high incidence of spontaneous tumors in the glandular stomach of mastomys (Praomys (mastomys) natalensis), we wanted to investigate if mastomys might be an useful model for our further studies. Tumors. were recognized in several organs of our mastomys, but not in the stomach. However, a high incidence oftrichobezoars was observed in the stomach and intestine, and obstruction from these was the cause of illness and death for many of them. Multiple factors are involved in the formation of bezoars. and these are discussed in relation to the occurrence in our mastomys colony., Scandinavian Journal of Laboratory Animal Sciences, Vol. 20 No. 4 (1993)

Published
2019
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35. Gastric cancer and gastrin:on the interaction of Helicobacter pylori gastritis and acid inhibitory induced hypergastrinemia

Author

Waldum, Helge L, Rehfeld, Jens F., Waldum, Helge L, and Rehfeld, Jens F.

Abstract

Gastric cancer, a disease with a reduced frequency for decades, now appears to be on the rise again in young Americans. The epidemiology of gastric cancer differs between tumors in the cardia and those of the more distal parts of the stomach. The tumors are divided into the intestinal type showing glandular growth pattern and the diffuse type with a different pattern. The latter often expresses neuroendocrine and more specifically ECL-cell markers suggesting that they originate from the ECL cell, the target cell for the antral hormone, gastrin. Helicobacter pylori gastritis is accepted as the major cause of gastric cancer, but only after having induced oxyntic atrophy which reduces gastric acid secretion and thus induces hypoacidity leading to hypergastrinemia. Long-term hypergastrinemia is known to induce malignant neoplasia in the stomach of animals as well as man. Recently treatment with proton pump inhibitor after Helicobacter pylori eradication in patients with gastroesophageal reflux disease, has been reported to predispose to gastric cancer. Since profound acid inhibition is a well-known cause of gastric neoplasia, it is to be expected that Helicobacter pylori infection and profound acid inhibition has an additive or possibly potentiating effect on the development of gastric cancer.

Published
2019

36. Differential expression and regulation of SSTR2 messenger RNA in rat gastric antrum and corpus

Author

Sandvik, Arne K., Dimaline, Rod, Brenna, Eiliv, and Waldum, Helge L.

Subjects
Somatostatin -- Observations, Proteins -- Receptors, Messenger RNA -- Observations, Stomach -- Observations, Biological sciences
Abstract

Starvation and acid inhibition by omeprazole increase the concentration of mRNAs encoding somatostatin receptor2 (SSTR2) in the antrum of the stomach. Starvation increases the level of mRNAs encoding somatostatin in the antrum but acid inhibition decreases somatostatin mRNAs in both antrum and corpus. The antrum contains many subtypes of SSTR which are probably formed by splicing SSTR. SSTR2 is present mainly in the G cells and enterochromaffin-like cells of the antrum.

Published
1995

38. Gastrin regulates histidine decarboxylase activity and mRNA abundance in rat oxyntic mucosa

Author

Sandvik, Arne K., Dimaline, Rod, Marvik, Ronald, Brenna, Eiliv, and Waldum, Helge L.

Subjects
Gastrin -- Physiological aspects, Gastric mucosa -- Observations, Decarboxylases -- Research, Biological sciences
Abstract

A study of the influence of exogenous gastrin on histidine decarboxylase (HDC) activity and mRNA in rat oxyntic mucosa reveals that gastrin increases HDC activity and HDC mRNA abundance. The HDC enzyme function and mRNA regulate the meal-to-meal modulation of gastrin release and undergo simultaneous changes, indicating the influence of high levels of HDC mRNA in overall gastric mucosal HDC activity modulation.

Published
1994

41. Calcium mediates gastrin-induced gastric histamine release in the rat

Author

Sandvik, Arne K., Brenna, Eiliv, and Waldum, Helge L.

Subjects
Calcium ions -- Physiological aspects, Gastrin -- Physiological aspects, Histamine -- Physiological aspects, Stomach -- Secretions, Biological sciences
Abstract

The role of Ca2+ in gastrin-induced gastric histamine release from isolated, vascularly perfused rat stomach was investigated. The effects of different levels of Ca2+, the Ca2+ channel blockers verapamil and nicardipine, the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N'-tetraacetic acid/acetoxymethyl ester, caffeine, forskolin and 3-isobutyl-1-methylxanthine on gastrin-induced histamine release were determined. The results proved that Ca2+ mediates gastrin-induced histamine release from the rat stomach.

Published
1993

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