Histochemistry of mucosubstances in Brunner's-gland cells and duodenal goblet cells of two New World monkey species (Saimiri sciureus and Saguinus fuscicollis)

5HT expression in the stomach and duodenum of the Rhesus Monkey (Macaca mulatta)

This study aims to provide a histological description of different regions of the gastric and duodenal mucosa in Rhesus monkey, as well as to analyze the distribution and the relative frequency of 5-HT. The cardia region mucosa consists of simple columnar epithelium PAS + and AB + and the 5-HT cells were observed at the base of the gland (QA [5-HT cells]/mm²) = 8.72 ± 4.98). The body region, has a smaller number of glands. The 5-HT cells were found predominant in the base of the gastric glands. QA= 6.96 ± 3.81. When compared to body region, the stomach fundus has smaller gastric pits. The 5-HT cells are found at the base of the glands near the main cells. QA = 5.29 ± 2.09. The pylorus region was found to have deep pits and well-developed gastric glands. The 5-HT cells are scarce, at the base of the pyloric gland. QA = 1.18 ± 1.36. The duodenum presented goblet cells strong PAS + and AB +. 5-HT cells were found both in the lining epithelium and in the intestinal glands. QA = 8.16 ± 2.59.

Mechanisms of airway responses to esophageal acidification in cats

Acid in the esophagus causes airway constriction, tracheobronchial mucous secretion, and a decrease in tracheal mucociliary transport rate. This study was designed to investigate the neuropharmacological mechanisms controlling these responses. In chloralose-anesthetized cats (n = 72), we investigated the effects of vagotomy or atropine (100 μg·kg(-1)·30 min(-1) iv) on airway responses to esophageal infusion of 0.1 M PBS or 0.1 N HCl at 1 ml/min. We quantified 1) diameter of the bronchi, 2) tracheobronchial mucociliary transport rate, 3) tracheobronchial mucous secretion, and 4) mucous content of the tracheal epithelium and submucosa. We found that vagotomy or atropine blocked the airway constriction response but only atropine blocked the increase in mucous output and decrease in mucociliary transport rate caused by esophageal acidification. The mucous cells of the mucosa produced more Alcian blue- than periodic acid-Schiff (PAS)-stained mucosubstances, and the mucous cells of the submucosa produced more PAS- than Alcian blue-stained mucosubstances. Selective perfusion of the different segments of esophagus with HCl or PBS resulted in significantly greater production of PAS-stained mucus in the submucosa of the trachea adjacent to the HCl-perfused esophagus than in that adjacent to the PBS-perfused esophagus. In conclusion, airway constriction caused by esophageal acidification is mediated by a vagal cholinergic pathway, and the tracheobronchial transport response is mediated by cholinergic receptors. Acid perfusion of the esophagus selectively increases production of neutral mucosubstances of the apocrine glands by a local mechanism. We hypothesize that the airway responses to esophageal acid exposure are part of the innate, rather than acute emergency, airway defense system.

Excretion of starch and esterified short-chain fatty acids by ileostomy subjects after the ingestion of acylated starches

BACKGROUND

Short-chain fatty acids (SCFAs) have a role in maintaining bowel health and can assist in the prevention and treatment of colonic disease. The ability of acylated starches to deliver SCFAs to the large bowel has been shown in animal studies but has not been established in humans.

OBJECTIVE

The aim was to determine whether cooked, highly acylated starches were resistant to small intestinal digestion in ileostomy volunteers.

DESIGN

Volunteers consumed single doses of custards containing 20 g cooked acetylated, propionylated, or butyrylated high-amylose maize starches (HAMSA, HAMSP, and HAMSB, respectively) on each collection day. The amounts of starch and of esterified SCFAs ingested and subsequently excreted in the stoma effluent were measured. Custards containing unacylated high-amylose maize starch (Hylon VII, HAMS) and low-amylose maize starch (3401C, LAMS) were consumed as controls.

RESULTS

Between 73% and 76% of the esterified SCFAs survived small intestinal digestion, which showed the potential of acylated starches to deliver specific SCFAs to the large bowel. The resistance of starches to small intestinal digestion as measured by ileal excretion was significantly greater for HAMSA, HAMSP, HAMSB, and HAMS than for LAMS (P < 0.001). The concentration of acetate in stoma digesta was higher than expected in all groups; this additional acid may have been derived from endogenous sources.

CONCLUSIONS

Acylated starches are a potentially effective method of delivering significant quantities of specific SCFAs to the colon in humans. These products have potential application in the treatment and prevention of bowel disorders amenable to modulation by SCFAs.

Molecular anatomy of an endodermal gland: investigations on mucus glycoproteins and cell turnover in Brunner's glands of Didelphis virginiana using lectins and PCNA immunoreactivity

Brunner's glands are located in the submucosa of the proximal duodenum and are unique to mammalian species. The North American opossum (Didelphis virginiana) is generally regarded as a prototype marsupial that closely resembles fossil didelphids which can be placed at the beginning of mammalian evolution. The current investigation provided an opportunity for the analysis of secretory products from these glands in a species thought to be more closely related to earlier evolutionary forms. Extracts of Brunner's glands were subjected to SDS-PAGE and Western blotting. The results indicate the presence of two high molecular weight PAS-positive glycoprotein bands. In addition to these two PAS-positive bands, several other glycoprotein bands were detected in the high molecular weight range that bind several lectins which typically recognize O-linked carbohydrates indicative of mucus type glycoproteins. The same lectins bind to glandular structures in tissue sections. Comparison of lectin binding sites with the pyloric glands of the stomach and duodenal goblet cells indicates that Brunner's glands carbohydrate residues resemble those of the pyloric glands more closely than those of the duodenal goblet cells. The low cell turnover rate in Brunner's glands is in contrast to the rapid turnover rate of goblet cell precursors in the duodenal crypts. The mucus composition and the cell turnover rate correlate well with embryological data and suggest that Brunner's glands of Didelphis evolved from an epithelium more closely associated with the stomach than that of the duodenum as the topography of the gland would suggest.

Ultracytochemistry of glycoconjugates in pig duodenal gland

To elucidate the ultrastructure, glycoprotein profile and site of glycosylation of glandular cells in relation to the functional polarity of the organelles, swine duodenal tissue was embedded in glycol methacrylate and subsequently stained for periodic acid thiocarbohydrazide silver proteinate (PA-TCH-SP), high iron diamine (HID)-TCH-SP, low iron diamine (LID)-TCH-SP, ninhydrin T-TCH-SP and five peroxidase-labeled lectins. The secretory granules in the duodenal gland cells were electron lucent with a 200 nm to 500 nm electrondense core. Glycoconjugates were confined to the secretory granules and elements of the Golgi complex. Protein activity was located only in the electron dense core. Achivementestic staining pattern for Concanavalin A (Con A), peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I), wheat germ agglutinin (WGA) and soybean agglutinin (SBA) was observed in stained secretory granules and the Golgi apparatus. A few cis cisternae were stained with SBA and UEA-I. Trans cisternae were stained with WGA and PNA. Con A reacted with seromucous granules and rough endoplasmic reticulum. These observational findings suggest that these are seromucous cells. The Golgi apparatus is the site of glycosylation and can be divided into two distinct compartments.

Histochemical characterization of carbohydrate residues during the morphogenesis of gastrointestinal and respiratory systems of Caretta caretta

The distribution of carbohydrates in the gastrointestinal and respiratory tract of Caretta caretta during embryogenesis and postnatal development was investigated by histological and histochemical techniques and using fluorescein-labelled lectins. The results indicate that the compartmentalised expression of glycoconjugates found in the juvenile Caretta caretta is acquired during development. The occurrence of neutral carbohydrates in cells and extracellular matrix was dependent on the developmental stage of the animal. In general, periodic acid Schiff positive glycoconjugates of the respiratory tract occurred at an earlier stage of development than those from the gastrointestinal system. The lectin binding pattern of both organ systems revealed a more refined pattern of the types of carbohydrates present during development. Wheat germ agglutinin showed the broadest binding pattern, whereas Soy bean agglutinin and phythaemagglutinin were more limited in their binding to tissue structures. The terminal carbohydrates detected in the gastrointestinal and respiratory tract of Caretta caretta were similar to those observed in mammals; this finding emphasises the suitability of Caretta caretta as a model system for amniote development.

Phospholipid- and neutral lipid-containing organelles of rat gastroduodenal mucous cells. Possible origin of the hydrophobic mucosal lining

In this study, an attempt was made to localize the cell types and subcellular organelles that synthesize and secrete surface-active lipids from the rat gastroduodenal mucosa. Two fluorescent hydrophobic probes--Nile Red and 1-anilinonaphthalene-8-sulfonic acid--and a phospholipid-selective cytochemical stain--iodoplatinate--were used for fluorescence and electron microscopic studies, respectively. The results showed the presence of phospholipid and neutral lipid fluorescent hot spots in the mucous cells of both the gastric mucosa and the submucosal Brunner's glands of the duodenum. In contrast, other cell types of the stomach (parietal, chief, and endocrine cells) or the duodenum (goblet cells and villous and crypt enterocytes) were either unreactive or weakly stained with the dyes. Ultrastructurally, two classes of large infranuclear inclusion bodies were observed in these two types of mucous cells. The location and size of these inclusion bodies appeared to be in agreement with the position and size of the large hydrophobic fluorescent hot spots detected at the light microscopic level. The ultrastructural appearance, localization, and histochemical staining pattern of these lipid-containing organelles suggest that they are specific for these cell types and not a general feature of degenerative epithelium undergoing lysosome-induced autolysis. It was concluded that the mucous cells of both the stomach and the Brunner's glands contain a subcellular organelle that stores hydrophobic material constituting both neutral lipids and phospholipids. These lipidic substances may be secreted into the gastroduodenal mucous gel and provide its surface with a nonwettable lining to repel luminal acid.

Lectin histochemistry of mammalian Brunner's glands

Lectin histochemical study was performed on twenty-eight specimens of formalin-fixed paraffin embedded tissues of proximal duodenum from human, cat, dog and Rhesus (macaque) monkey to demonstrate the pattern of carbohydrate residues in submucosal glands of Brunner as compared to that of the duodenal absorptive and goblet cells. Ten different biotinylated lectins were used as probes, and avidin-biotin-peroxidase (ABC) or avidin-gold-silver (AGS) complexes were used as "visualants". Brunner's gland cells of the four species studied exhibited a similar lectin-binding pattern which differ from other duodenal cells. The epithelium of Brunner's gland stained intensely with Ricinus communis agglutinin-I (RCA-I), succinylated-WGA (S-WGA) and wheat-germ agglutinin (WGA), moderately with Bandeirea simplicifolia agglutinin-I (BS-I), Concanavalia ensiformis agglutinin (Con A) peanut agglutinin (PNA) and Ulex europaeus agglutinin-I (UEA-I) and occasionally with Dolichos biflorus agglutinin (DBA), Lens culinaris agglutinin (LCA) and soybean agglutinin (SBA). Desialylation with neuraminidase resulted in only a slight elevation in binding intensities of PNA, DBA and SBA, indicating that glycoconjugates of the Brunner's gland cells are rich in asialo-oligosaccharides, which differs from duodenal epithelial cells. In addition, these histochemical reagents were useful in localizing Brunner's gland elements in the duodenal mucosa.