泽陆蛙消化道组织学观察

采用解剖学和组织学的方法对泽陆蛙消化道各部分的形态和组织学结构进行了观察。泽陆蛙的消化道分为口腔、咽、食道、胃、十二指肠、回肠和大肠。各管壁都由黏膜层、黏膜下层、肌层和外膜组成。食道黏膜层有皱褶和纤毛,无杯状细胞;胃黏膜层有杯状细胞和胃腺,黏膜下层有血管分布;小肠具绒毛、杯状细胞和肠腺,大肠皱褶少,杯状细胞也少。     

An histological and immunocytochemical study of the neuroendocrine cells in the intestine of Podarcis hispanica Steindachner, 1870 (Lacertidae)

Summary Numerous endocrine cells can be observed in the gut of the lizard Podarcis hispanica after application of the Grimelius silver nitrate technique. The argyrophilic endocrine cells are usually tall and thin in the small intestine but short, basal, and round in the large intestine. Eleven types of immunoreactive endocrine cells have been identified by immunocytochemical methods. Numerous serotonin-, caerulein/gastrin/cholecystokinin octapeptide-and peptide tyrosine-tyrosine-immunoreactive cells; a moderate number of pancreatic polypeptide-, neurotensin-, somatostatin-, glucagon-like peptide-1-and glucagon-immunoreactive cells, and few cholecystokinin N-terminal-and bombesin-immunoreactive cells were found in the epithelium of the small intestine. Coexistence of glucagon with GLP-1 or PP/PYY has been observed in some cells. In the large intestine a small number of serotonin-, peptide tyrosine-tyrosine-, pancreatic polypeptide-, neurotensin-, somatostatin-and glucagon-like peptide-1-immunoreactive cells were detected. Vasoactive intestinal peptide immunoreactivity was found in nerve fibers of the muscular layer. Substance P-immunoreactive nerve fibers were detected in lamina propria, submucosa and muscular layer. Chromogranin A-immunoreactive cells were observed throughout the intestine, although in lower numbers than argyrophilic cells.     

Ultrastructure of the hindgut of Drosophila larvae, with special reference to the domains identified by specific gene expression patterns

The hindgut of Drosophila larvae consists of nine domains that have been distinguished by specific gene expression patterns. In the present study, we examined the ultrastructure of the hindgut of Drosophila larvae, with special reference to the domains, in order to determine whether or not the domains are morphologically distinct functional units. Each domain showed specific ultrastructural features that suggested specific corresponding functions. According to the morphological features, terms are proposed for each domain: the imaginal ring; the "pylorus," which has a thick cuticular layer and well-developed sphincter muscles; the "large intestine," which occupies a major middle portion of the hindgut and has a unique dorsal and ventral subdivision; "border cells," which delineate the anterior and posterior borders of the large intestine and the border between the dorsal and ventral domains of the large intestine; and the "rectum," which is situated at the posterior end of the hindgut and has a thick cuticular layer and sphincter muscles. The morphological features indicate that the large intestine has active absorptive activities. The domains, which have been distinguished by gene expressions, were demonstrated to be functional tissue units of the gut.     

Sphingosine 1-phosphate-mediated trafficking of pathogenic Th2 and mast cells for the control of food allergy

Sphingosine 1-phosphate (S1P) has been proposed as a regulator of lymphocyte trafficking, but its role in mucosa-associated diseases, such as in food allergies, remains to be elucidated. To examine the role of S1P in allergic diseases in the intestine, we used a Th2 cell-mediated Ag-specific allergic diarrhea model and demonstrated that type 1 S1P receptor (S1P(1)) expression was preferentially associated with pathogenic CD4(+) T cells for the development of allergic reactions. Consistent with this demonstration, treatment with FTY720, a modulator of the S1P(1), prevented allergic diarrhea by inhibiting the migration of systemically primed pathogenic CD4(+) T cells induced by oral challenge with allergen into the large intestine. In addition, FTY720 hampered mast cell infiltration into the large intestine, whereas eosinophil infiltration into the large intestine and total and allergen-specific serum IgE production were comparable between mock- and FTY720-treated groups. These results suggest that modulation of the S1P-mediated pathway to inhibit the migration of pathogenic CD4(+) T cells and mast cells into the large intestine could be a novel strategy for preventing allergic diarrhea.     

Comparative expression of hexose transporters (SGLT1, GLUT1, GLUT2 and GLUT5) throughout the mouse gastrointestinal tract

Hexose transporters play a pivotal role in the absorption of food-derived monosaccharides in the gastrointestinal tract. Although a basic knowledge of the hexose transporters has already been gained, their detailed distribution and comparative intensities of expression throughout the gastrointestinal tract have not been fully elucidated. In this study, we quantitatively evaluated the expression of SGLT1, GLUT1, GLUT2, and GLUT5 by in situ hybridization and real-time PCR techniques using a total of 28 segments from the gastrointestinal tract of 9-week-old mice. GLUT2 and GLUT5 mRNA expressions were detected predominantly from the proximal to middle parts of the small intestine, showing identical expression profiles, while SGLT1 mRNA was expressed not only in the small intestine but also in the large intestine. Notably, GLUT1 mRNA was expressed at a considerable level in both the stomach and large intestine but was negligible in the small intestine. Immunohistochemistry demonstrated the polarized localization of hexose transporters in the large intestine: SGLT1 on the luminal surface and GLUT1 on the basal side of epithelial cells. The present study provided more elaborate information concerning the localization of hexose transporters in the small intestine. Furthermore, this study revealed the significant expression of glucose transporters in the large intestine, suggesting the existence of the physiological uptake of glucose in that location in mice.     

Differential activities of peroxisomes along the mouse intestinal epithelium

The presence of peroxisomes in mammalian intestine has been revealed formerly by catalase staining combined with electron microscopy. Despite the central role of intestine in lipid uptake and the established importance of peroxisomes in different lipid‐related pathways, few data are available on the physiological role of peroxisomes in intestinal metabolism, more specifically, α‐, β‐oxidation, and etherlipid synthesis. Hence, the peroxisomal compartment was analyzed in more detail in mouse intestine. On the basis of immunohistochemistry, the organelles are mainly confined to the epithelial cells. The expression of the classical peroxisome marker catalase was highest in the proximal part of jejunum and decreased along the tract. PEX14 showed a similar profile, but was still substantial expressed in large intestinal epithelium. Immunoblotting of epithelial cells, isolated from the different segments, showed also such gradient for some enzymes, ie, catalase, ACOX1, and D‐specific multifunctional protein 2, and for the ABCD1 transporter, being high in small and low or absent in large intestine. Other peroxisomal enzymes (PHYH, HACL1, and ACAA1), the ABCD2 and ABCD3 transporters, and peroxins PEX13 and PEX14, however, did not follow this pattern, displaying rather constant signals throughout the intestinal epithelium. The small intestine displayed the highest peroxisomal β‐oxidation activity and is particularly active on dicarboxylic acids. Etherlipid synthesis was high in the large intestine, and colonic cells had the highest content of plasmalogens. Overall, these data suggest that peroxisomes exert different functions according to the intestinal segment.     

Effect of cholera toxin on the ultrastructure of a primary culture of human fetal intestinal epithelium

Ultrastructure of the primary culture of epitheliocytes in the small and large intestine of 20-22-week-old human fetuses has been investigated, normal and 1, 3, 6, 12 and 24 h after administration of cholera toxin (choleragen) into the cell culture. The culture studied is mainly presented by absorbtive epitheliocytes, goblet, endocrinic and Paneth's cells, that preserve to a certain degree their differented structure. The most pronounced ultrastructural changes of the intestinal epitheliocytes in the primary cell culture, resembling those, that are previously noted in the epitheliocytes of the small and large intestine under influence of cholera toxin in various experimental animals in vivo, are revealed 3-6 h after administration of cholera toxin into the primary culture of the small intestine epitheliocytes and 6-12 h--into the large intestine epitheliocytes. The intestinal epitheliocytes of the human fetuses in the cell culture are sensitive to the action of cholera toxin and present a suitable model for studying the action mechanism of the toxin on the intestinal epithelium.     

Some morphological and histochemical studies on the intestinal tract of the Brazilian sloth (Bradypus tridactylus)

The intestinal of the 3-toed sloth, Bradypus tridactylus, was studied macroscopically, with light microscope and with histochemical methods for mucosubstances. Macroscopically, the inner surface of the duodenum shows longitudinal and circular folds. There is no caecum, nor appendix. The large intestine consists of a short colon and a large rectal pouch, which has a thick wall. The mucosa of the small intestine has long leaf-shaped villi covered with columnar epithelium having a well developed striated border, and the goblet cells are scattered among the columnar cells. An association between neutral and acidic mucosubstances was detected in the goblet cells. The duodenal (Brunner's) glands are confined exclusively in the lamina propria of the duodenum. No Paneth cells were observed in the crypt lining. Argyrophil and argentaffin cells were found in the entire length of the intestine. The large intestine does not possess villi, but many goblet cells were observed in its mucosa.     

Mechanisms of the antitumor action of spirobromine in mice with leukemia P-388

The influence of new antitumor drug, spirobromine, a derivative of dispirotripiperazine, on DNA synthesis in tumor cells and organs at different times after its injection into mice with P388 leukemia has been studied. The duration of DNA synthesis inhibition in tumor cells was found to correlate with spirobromine antitumor activity. A certain selectivity of action of the studied compound on DNA synthesis in P 388 leukemia cells as compared to the action on DNA synthesis in bone marrow, small intestine, spleen and liver of tumor animals was observed.     

Strongyloides ratti infection in the large intestine of wild rats, Rattus norvegicus

The large intestine of a rat has been neglected almost completely as a site of Strongyloides sp. infection. We reported that adult Strongyloides ratti remained in the large intestine for more than 80 days, producing more number of infective larvae than small intestine adults, and therefore hypothesized that parasitism in this site could be a survival strategy. In wild rats, however, no study has focused on large intestine infections of Strongyloides. The present study revealed that 32.4% of 68 wild rats, Rattus norvegicus, had the infection of S. ratti in the large intestine, with an average of 4.7 worms. These worms harbored normal eggs in the uterus. In a laboratory experiment with S. ratti and Wister rats, daily output of infective larvae by 4.7 females in the large intestine was estimated to be 4,638.4, suggesting that a few parasites could play a role in the parasite transmission. Five species of nematode found in the wild rats showed seasonality in infection intensity, with highest intensities in March-May. The number of S. ratti in the large intestine was also highest in these months.     

Development of the submucous plexus in the large intestine of the mouse

In the small intestine of both embryonic birds and mammals, neuron precursors aggregrate first at the site of the myenteric plexus, and the submucous plexus develops later. However, in the large intestine of birds, the submucosal region is colonised by neural-crest-derived cells before the myenteric region (Burns and Le Douarin, Development 125:4335-4347, 1998). Using antisera that recognize undifferentiated neural-crest-derived cells (p75NTR) and differentiated neurons (PGP9.5), we examined the colonisation of the murine large intestine by neural-crest-derived cells and the development of the myenteric and submucosal plexuses. At E12.5, when the neural crest cells were migrating through and colonising the hindgut, the hindgut mesenchyme was largely undifferentiated, and a circular muscle layer could not be discerned. Neural-crest-derived cells migrated through, and settled in, the outer half of the mesenchyme. By E14.5, neural-crest-derived cells had colonised the entire hindgut; at this stage the circular muscle layer had started to differentiate. From E14.5 to E16.5, p75NTR- and PGP9.5-positive cells were observed on the serosal side of the circular muscle, in the myenteric region, but not in the submucosal region. Scattered, single neurons were first observed in the submucosal region around E18.5, and groups of neurons forming ganglia were not observed until after birth. The development of the enteric plexuses in the murine large intestine therefore differs from that in the avian large intestine.     

The effect of extragastric vagotomy on gastric emptying and motility of the small intestine

Selective parasympathetic denervation of small and some large intestine has been performed in dogs. Chronic experiment on these dogs has revealed that this operation: has no effect on frequency and amplitude of intestine contractions during the first phase of the digestive process but it is accompanied by significant relaxation of the motor intestine activity in the second phase, causes a retardation of the rate of evacuation from stomach by 56.0% in dogs subjected to extragastric vagotomy as well as pH of chyme in the duodenum by 1-1.5 units above the norm.     

ANGPTL4 is produced by entero-endocrine cells in the human intestinal tract

Gut hormones produced by entero-endocrine cells (EEC) located throughout the gastrointestinal tract play a major role in the regulation of glucose and energy homeostasis. Angiopoietin-like 4 (ANGPTL4, also referred to as fasting induced adipose factor) is a secreted factor involved in regulation of lipid homeostasis and has been proposed as circulating mediator between the gut microbiota and fat storage in adipose tissue, although discordant data exist. Currently, little is known about the site and regulation of ANGPTL4 production in the intestine. Here, we show using immunohistochemistry and immunofluorescence that cells positive for ANGPTL4 are scattered along the epithelial layer in the human small and large intestine. ANGPTL4-positive cells exhibit typical features of EEC characterized by large ANGPTL4-positive secretory granules directed towards the basolateral side. In support, extensive overlap was observed between ANGPTL4-positive cells and cells positive for the entero-endocrine marker chromogranin A. Higher resolution images revealed that ANGPTL4 and chromogranin A are partially present in distinct intracellular vesicles. Using entero-endocrine HuTu-80 cells, ANGPTL4 secretion was shown to be induced by short chain fatty acids and reduced by bile acids. Finally, levels of ANGPTL4 in human plasma were significantly decreased following meal consumption. In conclusion, ANGPTL4 is produced by EEC in human intestine and expression may be regulated by short chain fatty acids and bile acids.     

Effects of NT on gastrointestinal motility and secretion, and role in intestinal inflammation

It is well established that interactions of neuropeptides with several cell types at various parts of the intestine are critically involved in intestinal pathophysiology. Among them, neurotensin has been identified as an important mediator in the development and progress of several gastrointestinal functions and disease conditions, exerting its effects by interacting with specific receptors that exert direct and indirect effects on nerves, epithelial cells, and cells of the immune and inflammatory systems. This review summarizes our recent understanding on the participation of neurotensin in the physiology and pathophysiology of the small and large intestine, and discusses various mechanisms that could be involved in these actions.     

A method for assessing the microflora status of the large intestine using a computer

The qualitative and quantitative composition of the microflora of the large intestine has been studied in 31 healthy adults and in 137 patients with acute viral hepatitides A and B. A set of quantitative tests ensuring the complete characterization of the microbiocenosis under study has been proposed. The results obtained in this investigation have been processed by means of a computer with the use of the principles of numeric taxonomy, thus making it possible to obtain the objective criterion of the state of the microflora of the large intestine, expressed by the similarity index.     

Peroxidase activity in the epithelium of the digestive tract of the bullfrog, Rana catesbeiana

Peroxidase activity was examined cytochemically in the mucosal epithelium along the length of the digestive tract from the esophagus through the large intestine during the development of the bullfrog, Rana catesbeiana. In the tadpole of this species, cells with peroxidase activity were found abundantly in the esophagus, stomach, and large intestine; and the types of such cells differed according to the region: ciliated cells and mucous cells in the esophagus; ciliated cells in the stomach; and brush cells, absorptive cells, and goblet cells in the large intestine, respectively. After metamorphosis, however, peroxidase activity was observed exclusively in absorptive cells and goblet cells in the large intestine. Peroxidase activity was commonly demonstrated in apical vesicles or granules, to some degree in rough endoplasmic reticulum, and in some elements of the Golgi apparatus. Furthermore, reaction product was also found in mucus covering the luminal surface of such epithelial cells. These findings indicate that peroxidase-positive cells, which may have the ability to synthesize peroxidase as a secretory product, were distributed mainly in three regions of the digestive tract in tadpoles (esophagus, stomach, and large intestine), but were centered in one specific region, the large intestine, after metamorphosis. Concomitantly, the variety of types of peroxidase-positive cells decreased during metamorphosis. Our results indicate that some of the peroxidase in the digestive tract may have a secretory origin and may play a role in the defense against microorganisms.     

Endocrine cells in the large intestine epithelium in various vertebrate species

Amount of argyrophile and argentoffin endocrine cells per 1 mm2 of the large intestine mucous membrane has been counted in the turtle, pigeon, white rat and frog at various periods of their life (winter hibernation, awakening, active life). As the animal's organization becomes more complicated, the amount of the endocrine cells in the epithelium increases both in the initial and in the terminal parts of the large intestine, their amount in the terminal (rectum) part being less than in the initial one. The greatest amount of the endocrine cells is found in simmer frogs at the expense of increasing content of the elements that do not belong to the argentaffin group. The latter do not significantly change during various seasons.     

Expression of the monocarboxylate transporter 1 (MCT1) in cells of the porcine intestine

Uptake of energy into cells and its allocation to individual cellular compartments by transporters are essential for tissue homeostasis. The present study gives an analysis of MCT1 expression and its cellular occurrence in the porcine intestine. Tissue portions from duodenum, jejunum, ileum, colon ascendens, colon transversum and colon descendens were collected and prepared for immunohistochemistry, Western blot and real time RT-PCR. A 169bp porcine MCT1 cDNA fragment was amplified and published. MCT1 mRNA expression in the large intestine was 20 fold higher compared to the small intestine. Western blot detected a single protein band of 41kDa at a much higher amount of MCT1 protein in the large intestine vs. the small intestine. MCT1 protein was detected in mitochondrial fractions of the large but not the small intestine. Immunohistochemistry in the small intestine showed that immune cells in the lamina propria and in the lymphoid follicles primarily expressed MCT1 while in the colon epithelial cells were the main source of MCT1. In summary, cellular expression of MCT1 differs between epithelial cells in the colon and small intestine. A possible role of MCT1 for uptake of butyrate into immune cells and the overall role of MCT1 for intestinal immune cell function remains elusive.