Biomedical subjects

H F Helander

Publications and source records attributed to H F Helander.

At least 91 records · Page 5Linked to original sources

PubMed1977

Secretory surface area and phosphatase activity of frog gastric mucosa.

Gastric mucosae were isolated from the European frog, R. temporaria, and after 5-7 h, stimulated with histamine (10(-4) M) and theophylline (5 mM). Acid secretion increased about fourfold, and this was accompanied by a threefold increase in secretory surface of the oxyntic cells, as determined in electron micrographs with conventional morphometric techniques. At the same time phosphatase activity of the secretory surface increased. Other experiments showed that the latter was due to an acid phosphatase, with pH optimum near 3. It appears that the increase in surface phosphatase with stimulation can be attributed to a diminished local pH and not to the increase in surface area demonstrated in this study.

Acid Phosphatase↗

PubMed1977

An attempt to correlate functional and morphological data for the gastric parietal cells.

In fed rats, acid production was estimated to be 7 X 10(8) molecules of HCl per cell per sec or 5 X 10(5) molecules per sec per mu2 of secretory surface. In stimulated frog mucosa the corresponding values were 3 X 10(8) molecules of HCl per cell per sec 2 X 10(5) molecules per sec per mu2 or secretory surface. The generous assumptions used in making these estimates could have led to large errors.

Animals↗

PubMed1977

Lipid islands in the gastric mucosa after resection for benign ulcer disease.

Lipid islands in the gastric mucosa are macroscopically well demarcated white or yellow-white patches, microscopically composed of accumulations of lipid-filled macrophages. The occurrence of lipid islands has not previously been linked to gastric surgery. This study presents the prevalence of lipid islands after Billroth I and Billroth II resection as well as in a nonoperated control group. Gastroscopy and multiple biopsies were performed at selected intervals after surgery. The occurrence of single or multiple lipid islands increased with the postoperative time, independent of the original ulcer disease or the type of operation performed. In nonoperated patients, lipid islands were found in 6.3%, and approximately the same prevalence was found 1 to 3 years after gastric surgery. A much higher prevalence was found 10 to 15 years postoperatively, and 23 years after Billroth II resection 60% of the patients demonstrated lipid islands. At repeated gastroscopic examinations over a period of 1 to 2 years, no certain changes in number, size, or distribution of the lipid islands were seen. The etiology of lipid islands is unknown, but intestinal-gastric reflux may be the most plausible etiological factor.

Adult↗

PubMed1976

Effects of secretagogues on oxygen consumption, aminopyrine accumulation and morphology in isolated gastric glands.

A recently developed method to isolate gastric glands from the rabbit gastric mucosa (Berglindh and Obrink 1976) was used to study the effects of some common gastric secretagogues. Three parameters were investigated: 1) Respiratory activity; 2) Intraglandular accumulation of the weak base aminopyrine; 3) Quantitative morphology of the parietal cells. The following substances were tested: Histamine, cAMP, db-cAMP, aminophylline, carbachol and pentagastrin. The strongest effect was obtained with db-cAMP which dose-dependently stimulated the respiration up to 200%, increased the aminopyrine accumulation 80% and altered the parietal cell morphology from a typically resting to a typically stimulated state. cAMP also stimulated the respiration but was about 10 times less effective on a molar basis than the dibutyryl form. Histamine, like db-cAMP, stimulated the respiration in a dose-dependent manner and strongly increased the aminopyrine accumulation. The morphological changes were, however, not of the same magnitude as after db-cAMP. Aminophylline, tested only for respiratory activity, stimulated the oxygen consumpation moderately. Carbachol induced a transient increase in both the oxygen consumption and in the aminopyrine accumulation with a peak value after approximately 15 minutes for both, but gave no significant morphological alterations. Pentagastrin, finally, was incapable of inducing changes in any of the three parameters. Aminopyrine was also found to accumulate approx. 50 times in unstimulated, morphologically resting glands. This seems to indicate that there might be acid sites already in resting glands.

Aminophylline↗

PubMed1976

Stereological changes in rat parietal cells after vagotomy and antrectomy.

Gastric parietal cells from 44 male adult Sprague-Dawley rats were studied in the electron microscope. The animals were divided into seven groups: normal fasted, normal nonfasted, 4 weeks after vagotomy, 10 weeks after vagotomy and pyloroplasty, 10 weeks after pyloroplasty, 4 weeks after antrectomy, and 10 weeks after antrectomy. Stereological data were obtained from 30 to 40 parietal cells in each animal. In the normal nonfasted rats the parietal cells high up in the glands had a larger secretory surface density than those at deeper levels of the mucosa. Neck parietal cells containing a few mucous granules constituted about 10% of the total number of parietal cells in the normal rats; they were most common in the midgland region. The average parietal cell volume in the normal fasted rats was calculated to be 1100 mu3; the cells were significantly smaller 10 weeks after vagotomy and pyloroplasty and still smaller 10 weeks after antrectomy. In this respect the results after vagotomy and pyloroplasty did not differ from those after pyloroplasty alone. The parietal cell density in the normal fasted rats averaged 144 X 10(3) cells per mm3; in the operated rats (except for the 4-week vagotomized rats) the cells became more numerous. The parietal cell volume density was about equal in all groups of animals, except for the 10-week antrectomized rats, where a significant reduction occurred.

Animals↗

PubMed1975

Reversibility of effects of very hypotonic fluids on in vitro frog gastric mucosa: a functional and morphological study.

Functional and morphological properties of the in vitro frog gastric mucosa were studied during and after exposure to very hypotonic (approximately 25 mOs M) solutions. Within 20 min the acid secretory rate decreased to zero, but it returned to normal levels after isotonic fluids had been restored. The potential difference (PD) dropped within the first minutes after the exposure to hypotonic solutions, and became inverted. Following the return of isotonic conditions the PD increased to levels higher than in the controls. The electrical resistance increased about 10-fold during the hypotonic period, but decreased to near normal values when isotonic conditions were restored. By light and electron microscopy the cells of the hypotonic mucosae appeared greatly swollen, and the alterations were assessed by morphometric methods. The gland lumina were almost obliterated, and the lamina propria was reduced to about 63% of its former volume. After the return to isotonic conditions normal morphology was restores. It is conceivable that the great increase in resistance duroing the hypotonic period was caused by the occlusion of the gland lumina. Quantitative analyses of the Na, K, and Cl tissue concentrations indicated a large loss of these ions during the hypotonic state. Presumably the epithelial cells in the hypotonic mucosae avoid bursting by rapidly letting large numbers of ions exit, which results in a celulular osmolarity close to that of the bathing fluids.

Animals↗

PubMed1975

Enzyme patterns and protein absorption in rat colon during development.

Four enzymes were studied in the rat colon during perinatal development, namely, carbonic anhydrase, beta-D-galactosidase, and alkaline and acid pphosphatase. Quantitative analyses of tissue extracts revealed a peak in carbonic anhydrase activity 10 days after birth and histochemically most of the enzyme was found at the surface of the colonic mucosa. A similar localization was found for beta-D-galactosidase, which displayed a peak of activity in the 1-day-old rats. Alkaline phosphatase activity reached its maximum 5 days after birth, and by electron-microscopical histochemistry this enzyme was traced to the microvillous border, supranuclear vesicles and tubules, meconium bodies and the lateral surfaces of the principal cells. Acid hosphatase activity was also found in the microvillous border, in the supranuclear vacuoles and meconium bodies and in the Golgi apparatus. In the infant rat colon all these enzymes had higher activities and sometimes a different localization than in the adult rat, which indicates functional differences between the young and the adult animals. An example is the absorption of proteins. Peroxidase and insulin, given as enemas, were absorbed in the infant rat colon, but this capacity was much reduced after weaning.

Acid Phosphatase↗

PubMed1975