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Imaging, Three-Dimensional↗
Biomedical subjects
Herbert F Helander
Publications and source records attributed to Herbert F Helander.
Cell proliferation in the gastric epithelium of the ulcer rat.
OBJECTIVE: Cell division is brisk in the ulcer margin and many of the new cells will migrate over and cover the ulcer bed. The aim of this study was to determine how agents that promote or delay gastric ulcer healing influence cell proliferation in the gastric epithelium. MATERIAL AND METHODS: Acetic acid ulcers were produced in the rat gastric corpus; non-ulcer rats served as controls. All rats were given a continuous infusion of (3)H-thymidine. Some rats were also given gastrin or indomethacin, or infected with Helicobacter pylori. The rats were killed after 1, 2, 6 or 13 days, and the ulcer margin and undamaged corpus were excised for determination of labeling index (LI) by autoradiography. Antrum, duodenum and colon were also studied. Silver grain counting was carried out in some groups. RESULTS: LI in the ulcer margin grew exponentially, reaching 84% after 6 days; gastrin increased, and indomethacin decreased LI significantly. In 6-day ulcer rats that were given 3H-thymidine only during the first day LI was 5%, while in those given 3H-thymidine only during the last day LI was 27%. LI and silver grain counting results indicated that during the first 6 days of healing the epithelial cells in the ulcer margin divide twice. In the undamaged epithelium of the 1-day ulcer rats LI was <one-third, and in the antral epithelium one-half of that in the non-ulcer controls. CONCLUSIONS: During the first 6 days of healing, the LI of the non-parietal epithelial cells increases exponentially in the ulcer margin; this is enhanced by gastrin. The unexpected finding in the ulcer rats of decreased LI in undamaged oxyntic and antral epithelium may be caused by a block of the G1 restriction point in the cell cycle. The reason for this remains obscure.
Acetic Acid↗
The bradykinin BK2 receptor mediates angiotensin II receptor type 2 stimulated rat duodenal mucosal alkaline secretion.
BACKGROUND: This study investigates bradykinin and nitric oxide as potential mediators of AT2-receptor-stimulated duodenal mucosal alkaline secretion. Duodenal mucosal alkaline secretion was measured in methohexital- and alpha-chloralose-anaesthetised rats by means of in situ pH-stat titration. Immunohistochemistry and Western blot were used to identify the BK2 receptors. RESULTS: The AT2 receptor agonist CGP42112A (0.1 microg kg(-1) min(-1)) administered intravenously increased the duodenal mucosal alkaline secretion by approximately 50 %. This increase was sensitive to the selective BK2 receptor blocker HOE140 (100 ng/kg i.v.), but not to luminal administration of the NOS blocker L-NAME (0.3 mM). Mean arterial pressure did not differ between groups during the procedures. Immunohistochemistry showed a distinct staining of the crypt epithelium and a moderate staining of basal cytoplasm in villus enterocytes. CONCLUSION: The results suggest that the AT2-receptor-stimulated alkaline secretion is mediated via BK2 receptors located in the duodenal cryptal mucosal epithelium.
Animals↗
Secretion from submucosal salivary glands of the ferret in response to a cholinesterase inhibitor applied onto the oral mucosa.
Parasympathomimetics or cholinesterase inhibitors taken orally may relieve dry-mouth symptoms, but this route of administration is often associated with adverse systemic reactions. In the present study, an animal model was worked out aimed at stimulating the submucosal glands and avoiding systemic effects. In the anesthetized ferret, saliva from the parotid, sublingual and submandibular glands was prevented from reaching the mouth. Vehicle or physostigmine was applied topically for 10 min on the buccal and labial mucosa on one side, while the other side served as a control. Fluid from each side was collected every 5 min Mean basal secretion was 0.17 mg 5 min(-1). The response to physostigmine 0.1% did not exceed that of the vehicle. At higher concentrations the responses lasted 80-120 min. Peak secretion was nine (0.25% physostigmine), 13 (0.5% physostigmine) and 40 (1% physostigmine) times higher than baseline. At 1% physostigmine, the secretion from the control side was elevated, and a small flow from the duct-cannulated parotid gland occurred, indicating systemic effects. Arterial blood pressure was well maintained. Additional observations on the duct-cannulated zygomatic gland showed that secretion from this gland increased already within the 10-min period of application of physostigmine to the overlying mucosa. The distance between the mucosa and the zygomatic gland was only about 1 mm. Physostigmine-induced secretion was abolished by atropine. Local gland stimulation may be an attractive alternative for the treatment of dry mouth.
Administration, Buccal↗