Studies on the G cells of the pyloric mucosa, the probable site of gastrin secretion

Proton Pump Inhibitors and Fracture Risk: A Review of Current Evidence and Mechanisms Involved

The number of patients with gastroesophageal problems taking proton pump inhibitors (PPIs) is increasing. Several studies suggested a possible association between PPIs and fracture risk, especially hip fractures, but the relationship remains contentious. This review aimed to investigate the longitudinal studies published in the last five years on the relationship between PPIs and fracture risk. The mechanism underlying this relationship was also explored. Overall, PPIs were positively associated with elevated fracture risk in multiple studies (n = 14), although some studies reported no significant relationship (n = 4). Increased gastrin production and hypochlorhydria are the two main mechanisms that affect bone remodeling, mineral absorption, and muscle strength, contributing to increased fracture risk among PPI users. As a conclusion, there is a potential relationship between PPIs and fracture risks. Therefore, patients on long-term PPI treatment should pay attention to bone health status and consider prophylaxis to decrease fracture risk.

Cell proliferation in pathogenesis of esophagogastric lesions in pigs

Esophagogastric ulcer is an independent disease in swine that is characterized by ulcerous autodigestion of the cutaneous mucosa, which does not exhibit a tendency to recover, but, on the contrary, a tendency toward severe hemorrhaging, with a predominantly lethal outcome. Since it develops in the part of the stomach that is morphologically and functionally different from other glandular mucosa, it was questioned earlier whether it could be a peptic ulcer based on its nature. Spontaneous ulcers, usually of the stomach, commonly occur in many domestic animals. Some of these lesions are chronic and they may occur in either the glandular or squamous-lined regions of the stomach. As with the human disease, the pathogenesis in domestic animals is multifactorial, poorly understood, and variable between and within species. Environmental stress and dietary factors are very important in the ulcer disease in swine. It has been shown that the Helicobacter spp. is strongly associated with naturally occurring ulcer and preulcer lesions of the pars esophagea in swine, which raises the possibility that Helicobacter spp. is an important factor in the pathogenesis of these lesions. The dynamics of the development of esophagogastric ulcers imply hyperplastic lesions (parakeratosis and hyperkeratosis), keratolysis, erosions, peptic necrosis, and the development of ulcers with all the characteristics of peptic ulcerations in other localities. In addition, K6 is expressed in association with the mucosal changes. The pattern of the intermediate filaments of keratin suggests that epithelial proliferation, which leads to visible hyperkeratosis, constitutes the essence of gastric ulcers in swine.

The relationship between gastrin cells and bombesin-like immunoreactive nerve fibres in the gastric antral mucosa of guinea-pig, rat, dog and man

The relationship between bombesin-like immunoreactive (bombesin-LI) nerve fibres and gastrin-LI G-cells was examined in gastric antral mucosa from guinea-pig, rat, dog and man using a double-labelling fluorescence immunohistochemical technique. The greatest density of bombesin-LI nerve fibres was found within the basal mucosa in all species and the density of innervation decreased towards the luminal surface. Most G-cells were in a band occupying approximately the middle third of the mucosa. The proportion of G-cells found within a distance of 2 microns from bombesin-LI nerve fibres was low in all species (6% in the guinea-pig, 22% in the rat, 14% in the dog, and 9% in the human). It is proposed that the neuropeptide released from bombesin-LI antral mucosal nerve fibres traverses distances of greater than several microns to reach the target G-cells. This may be achieved by passage through the mucosal microcirculation.

Ultrastructural studies of endocrine cell populations showing an argentaffin reaction and/or serotonin immunoreactivity in the rat antral mucosa

On the basis of staining results in closely related semi-thin sections from rat antral mucosa immunostained with polyclonal serotonin antibodies and silver-stained for the argentaffin reaction, respectively, three different cell populations could be distinguished. One of these cell populations showed both serotonin immunoreactivity and an argentaffin reaction, a second one serotonin immunoreactivity alone, and a third one only an argentaffin reaction. These cell populations were studied electron microscopically in ultra-thin sections located between the stained semi-thin sections. The cell population displaying an agentaffin reaction and serotonin immunoreactivity showed secretory granules of the enterochromaffin cell type. A similar granular appearance was observed in cells which only exhibited an argentaffin reaction. Serotonin immunoreactivity in the absence of an argentaffin reaction was evident in some G (gastrin) cells, and in some D1 and possibly also some D (somatostatin) cells; but not all the endocrine cells of the non-enterochromaffin type displayed serotonin immunoreactivity. The significance of the different reactions in the three cell populations is discussed.

Morphological variation of immunoreactive cells positive to cholecystokinin 33 (10-20) and gastrin 34 (1-15) in human duodenum

Human duodenal endocrine cells reactive with antibodies to cholecystokinin (CCK) 33 (10-20) and/or gastrin 34 (1-15) were studied by a combination of immunohistochemical and electron-microscopic methods. By immunohistochemistry, three types of endocrine cells were distinguished in human duodenal mucosa, i.e., those only positive for only CCK, those positive for both CCK and gastrin and those only positive for only gastrin. Ultrastructurally, the first cell type is characterized by many secretory granules with an eccentric dense core (mean diameter; 271 +/- 74 nm). The second cell type, which was less frequent than the other two, has ultrastructural features that resemble type-I cells. The last cell type was composed of two types of cells containing small secretory granules identical to those of IG cells (mean diameter; 171 +/- 31 nm) or large secretory granules indistinguishable from those of I cells (mean diameter; 286 +/- 50 nm).

A study on the distribution of G-cells in human gastric mucosa

The distribution of G-cells in the gastric glands was studied quantitatively using the indirect immunoperoxidase method in 37 resected stomachs: 11 for esophageal cancer, 14 for gastric cancer, 4 for gastric ulcer, 7 for duodenal ulcer, and 1 for atypical epithelium. G-cells were seen in the pyloric glands and in the pseudopyloric glands in the atrophic fundic gland area. No G-cells were found in the fundic glands or in the cardiac glands. There was a significant correlation between the number of G-cells and the pyloric and/or pseudopyloric glandular tubes (p less than 0.01). The number of G-cells per glandular tube was 1.9 +/- 0.5 in the pyloric glands and 1.2 +/- 0.4 in the pseudopyloric glands on the pyloric part of the atrophic fundic gland area. G-cells were rarely seen in the pseudopyloric glands on the cardiac part of the atrophic fundic gland area. It is suggested that the pseudopyloric glands without G-cells in the cardiac region are akin to cardiac glands.

Pancreatic polypeptide (PP) cells in the PP-rich lobe of the human pancreas are identified ultrastructurally and immunocytochemically as F cells

The ultrastructure of immunohistochemically identified PP cells has been investigated by applying the serial semithin/thin section technique to the human pancreas, with special reference to the posterior part of the head, reputed to originate from the ventral primordium. PP cells of this area differ from those already identified in the rest of the pancreas and correspond to a cell, not yet described in the human pancreas, characterized by larger granules of very variable shape and structure. Such granules resemble those of so-called "F cells", i.e. the PP cells of dog uncinate process and cat duodenal lobe, also coming from the ventral primordium. Thus, human "ventral lobe" PP cells have peculiar potentialities which are expressed in distinctive structural patterns of presently unknown functional meaning.

Antropyloric G-cell hyperplasia in hypercalcemic rabbits bearing the VX2 carcinoma

The number of distribution and the numbers of G cells in the antropyloric region of the rabbit stomach were mapped employing immunoperoxidase localization and morphometric quantitation and compared to similar analyses in hypercalcemic rabbits bearing the VX2 carcinoma. In normal animals, G cells were confined to the lower third of the antropyloric mucosa, where they were randomyly distributed within the mucosal glands. In contrast, tumor-bearing animals showed an extension of these cells into the middle third of the antropyloric mucosa. The absolute counts of G cells in control rabbits were 5.3 +/- 0.78 (mean +/- SE) per unit area, while those in hypercalcemic tumor-bearing rabbits were 11.9 +/- 0.46, a statistically significant increase. It is concluded that rabbits bearing VX2 carcinoma have G-cell hyperplasia.

[Development and function of endocrine cells in the proventriculus of the chicken (author's transl)]

An argyrophil endocrine cell type with typical intraepithelial development is seen initially on the 8th day of incubation in the epithelium of the main lumen of the chicken-proventriculus. During the embryonic period, rapid development of these cells can be observed with a quantitative maximum on the 13th day of incubation. At this time increased digestive efficiency is necessary for the chicken embryo with the start of gastric secretion combined with the first swallowing of albumen. There is a subsequent decrease in the number of endocrine cells in the main lumen epithelium, their function in hatched or adult specimens is largely taken over by cells which appear in the epithelium of the glands of the proventriculus on the 16th and later days of incubation. On the 2nd day after hatching the adult distribution pattern of endocrine cells in the proventriculus is attained.

Ultrastructure of endocrine cells in metaplastic epithelium of human gall bladder

Two endocrine cell types were found in the metaplastic epithelium of gall bladders removed for gall stones. The endocrine cell type I resembled the EC (enterochromaffin) cell of the normal stomach mucosa. The homogeneous and electron-dense secretory granules were variable in size and shape and mainly located in the sub-nuclear cytoplasm. The endocrine cell type II was similar to the ECL (enterochromaffin-like) cell of the human stomach. The secretory granules were almost exclusively present in a subnuclear location, and were round and homogeneous in size. The secretory material was slightly granular and often there was a clear zone (halo) between the granule core and the limiting membrane. A rich network of microfilaments in the cytoplasm, especially around the nucleus, was typical of the type II endocrine cell. Both cell types were closely related to the basement membrane and the capillaries underneath.

Formaldehyde-ozone-induced fluorescence in isolated gastrin granules

In several mammals the antral gastrin cells display characteristic formaldehyde-ozone-induced fluorescence (375/500-520 nm). Such fluorescence is also given by gastrinoma cells. Gastrin granules, isolated from gastrinomas and identified by immunofluorescence and electron microscopy, were found to show intense formaldehyde-ozone-induced fluorescence.

A fine structural characterization of the proliferated endocrine cells in atrophic gastric mucosa

This study shows that most of the proliferated endocrine cells in nonintestinalized epithelium in the body of stomachs in patients with pernicious anemia have the fine structure of ECL (enterochromaffin-like) cells, the principal endocrine cell in the body of normal stomachs, and notes an absence of G (gastrin) cells, the principal endocrine cell in the normal pylorus. Since gastrin has been identified in many of these proliferated cells by immunofluorescence, these findings question the position that gastrin synthesis in the stomach is only associated with G cells.

Electron microscope radioautographic identification of serotonin-synthesizing cells in the mouse gastric mucosa

This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP). Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-(3)H or 5-HT-(3)H. Their stomachs were processed for light- and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances. Stomachs from additional mice were incubated in vitro with 5-HT-(3)H and processed similarly. All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly. Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT. The newly synthesized 5-HT was associated with the intracellular granules. The gastric endocrine cells were not labeled by exogenous 5-HT-(3)H, whereas mast cells were labeled by either 5-HT-(3)H or 5-HTP-(3)H administration. The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism-that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time.

Immunofluorescent localization of secretin in the canine duodenum

The endocrine polypeptide (APUD) cells responsible for the production and storage of secretin have been demonstrated, in canine duodenum, by the application of an indirect immunofluorescence technique, using anti-pure porcine secretin, to carbodiimide-fixed cryostat sections. The cells are identified, by the use of parallel cytochemical and ultrastructural preparations, as the small granular S cells. These are essentially restricted to the transitional zone of the duodenal mucosa, with whose lumen their apical projections probably always make contact. There is no need to alter the title of the cells since S can now stand for secretin instead of for small.

The endocrine polypeptide cells of the human stomach, duodenum, and jejunum

Thirty specimens of stomach, duodenum, and jejunum, removed at operation, were examined by optical microscopical, cytochemical, and electron microscopical techniques. The overall distribution of four types of endocrine polypeptide cell in the stomach, and three in the intestine, was determined. The seven cell types are described by names and letters belonging to a scheme for nomenclature agreed upon at the 1969 Wiesbaden conference on gastrointestinal hormones. The gastrin-secreting G cell was the only cell for which firm identification with a known hormone was possible. Although there was wide variation in the distribution of the various cells, from one case to another, striking differences were nevertheless observable, with respect to the G cell, between antra from carcinoma and from ulcer cases.

Immunofluorescence studies on the distribution of gastrin cells in different clinical states

Examination of human gastric biopsies by an indirect immunofluorescence technique using antihuman gastrin confirms the variability in distribution and number of gastrin-secreting (G) cells (Solcia, Vassallo, and Capella, 1969) observed by morphological, cytochemical, and electron microscopical studies. In cases with presumed secondary hypersecretion a profound degree of G-cell hyperplasia is observed. Immunofluorescence with. antigastrin can provide valuable information on the state of the G cells in different physiological states, particularly if used in conjunction with other cytochemical techniques.