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谷氨酰胺及其前体对免疫系统的影响 总被引：1，自引：0，他引：1
谷氨酰胺是机体细胞外液中主要的自由氨基酸源,其主要作用是为肠上皮细胞和免疫细胞供能和补充氮源.针对谷氨酰胺在实际应用中的缺点,研究者将目光放在了谷氨酰胺替代物即其前体物的研究上,发现其前体物在使用上较之更为稳定有效. 相似文献
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谷氨酰股及其前体对免疫系统的影响 总被引：1，自引：0，他引：1
谷氨酰胺是机体细胞外液中主要的自由氨基酸源，其主要作用是为肠上皮细胞和免疫细胞供能和补充氮源。针对谷氨酰胺在实际应用中的缺点，研究者将目光放在了谷氨酰胺替代物即其前体物的研究上．发现其前体物在使用上较之更为稳定有效。 相似文献
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谷氨酰胺及其二肽与动物肠道营养免疫 总被引：1，自引：0，他引：1
谷氨酰胺(Glutamine，Gln)是哺乳动物体内含量最丰富的游离氨基酸。Gln不仅是快速分裂增殖细胞如肠上皮细胞和淋巴细胞的主要能量来源，而且可促进淋巴细胞增殖，在促进受损肠道的修复以及维持正常的局部免疫功能中发挥重要的作用。 相似文献
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动植物蛋白中谷氨酰胺和亮氨酸含量丰富且较稳定,而食物和动物体液中精氨酸含量差异较大。除在蛋白质合成中起作用外,这三种氨基酸可独自激活信号传导通路以促进蛋白质的合成,并可能抑制肠上皮细胞自噬介导的蛋白质降解。此外,谷氨酰胺和精氨酸可分别激活有丝分裂原活化蛋白激酶通路和哺乳动物雷帕霉素靶蛋白(mTOR)/p70(s6)激酶通路,从而加强粘膜细胞的迁移和修复。利用一氧化氮依赖型cGMP的信号级联,精氨酸可调节肠道多种生理活动,这有利于细胞的生存和维持动态平衡。动物体内外试验显示,谷氨酰胺和精氨酸可促进细胞增殖,并可针对养分损失、氧化损伤、应激和免疫应激来发挥不同的细胞保护作用。此外,一氧化氮存在时亮氨酸可加强肠道细胞的迁移。因此,通过细胞信号传导机制,精氨酸、谷氨酰胺和亮氨酸在肠道的生长发育和功能完善过程中发挥了关键作用。 相似文献
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谷氨酰胺二肽调节断奶仔猪生长性能的研究进展 总被引：1，自引：0，他引：1
谷氨酰胺是一种条件性必需氨基酸,谷氨酰胺二肽是谷氨酰胺和其他氨基酸形成的二肽。因其不仅能发挥与谷氨酰胺类似的生物学功能,而且还克服了谷氨酰胺的缺点,近年来受到了动物营养学家的广泛关注,国内外许多研究者也开展了谷氨酰胺及其二肽在动物上的研究工作。主要就谷氨酰胺二肽的生物学功能及对断奶仔猪生长性能的影响进行了综述。 相似文献
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小肠上皮细胞的体外培养对于研究肠上皮干细胞的增殖分化机理、肠上皮细胞间信号传导、营养物质的吸收利用及转化、肠道免疫等方面具有重要意义,但肠上皮细胞的分离培养难度较大,能成功建立单克隆肠上皮细胞系的报道较少。结合肠上皮干细胞的增殖分化规律,选择肠上皮细胞分离培养的最佳时期和分离方法,建立稳定传代的小肠上皮细胞系,对于各相关领域的研究均起到了重要作用。 相似文献
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Bacteria were detected in the enterocytes of the distal jejunum in weaned pigs on Days 7 and 9 post-infection (DPI) with Eimeria scabra in addition to the developmental stages of the coccidia. Short rod-shaped bacteria were identified in approximately 60% of the enterocytes that contained developmental stages of E. scabra. No such bacteria were observed in cells where coccidia were absent. Gamonts of cryptosporidia were also observed within the microvillous zone of the enterocytes in the distal jejunum of weaned pigs on DPI 9 with E. scabra. Cryptosporidia were present only in enterocytes harbouring stages of E. scabra. Chlamydial particles were also found in the cytoplasm of enterocytes 7 DPI with E. scabra. The presence of other enteropathogens exclusively in the enterocytes containing developmental stages of coccidia suggests that the coccidium E. scabra facilitates the invasion and development of bacteria, cryptosporidia and chlamydia in the enterocytes. 相似文献
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肠道葡萄糖转运载体研究进展 总被引：2，自引：0，他引：2
D-葡萄糖是机体的主要能源物质,对机体代谢与内环境稳态有非常重要的作用。葡萄糖的吸收主要通过位于肠黏膜上皮细胞的两类葡萄糖转运载体家族来完成。Na+与SGLTs的结合促使载体与葡萄糖的结合,葡萄糖顺着Na+的浓度梯度进入细胞;当细胞内葡萄糖浓度升高后,葡萄糖顺着浓度差通过肠黏膜上皮细胞基底膜GLUT2经易化扩散转运进入血液。本文综述了肠道不同葡萄糖转运载体家族的成员和分类,介绍了其结构特征、功能特性及其组织分布;并详细阐述了肠道葡萄糖转运载体基因表达的影响因素。 相似文献
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Okamoto M Furuoka H Horiuchi M Noguchi T Hagiwara K Muramatsu Y Tomonaga K Tsuji M Ishihara C Ikuta K Taniyama H 《Veterinary pathology》2003,40(6):723-727
Using an immunohistochemical method, we attempted to detect the transmission of abnormal prion protein (PrPsc) to the enterocytes of the small intestine of neonatal mice by oral exposure with sheep brain affected by scrapie. Five 1-day-old neonatal mice were exposed by oral inoculation to the homogenized brain of a scrapie-affected sheep. In the small intestine of all mice 1 hour after inoculation, immunoreactivity with antinormal prion protein (PrPc) antibody was seen in the cytoplasm of villus enterocytes. This finding suggests transmission of abnormal PrPsc into the cytoplasm of enterocytes. In control mice treated with normal sheep brain, no PrPc signal was seen in enterocytes of the small intestine. Immunopositivity for neurofilament protein and glial fibrillary acidic protein was seen in the cytoplasm of enterocytes of mice inoculated with scrapie and normal sheep brain. This suggests that the enterocytes of neonatal mice can absorb PrPsc and other macromolecular proteins of the sheep brain affected by scrapie and may be more important than previously thought as a pathway for PrPsc transmission in neonatal animals. 相似文献
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Dae Young Kim Mark A Mitchell Rudy W Bauer Rob Poston Doo-Youn Cho 《Journal of veterinary diagnostic investigation》2002,14(4):332-334
Thirty of 200 (15%) hatchling inland bearded dragons were found dead after a short period (48 hours) of weakness and lethargy. The most common clinical signs were head tilt and circling. Six bearded dragons with neurological signs were euthanized, and postmortem examination revealed no gross abnormalities. Microscopically, severe, randomly distributed hepatocellular necrosis with large basophilic intranuclear inclusion bodies in numerous hepatocytes was noted. Small-intestinal enterocytes contained intracytoplasmic coccidial protozoa (Isospora sp.) and occasional enterocytes had basophilic intranuclear inclusion bodies. Transmission electron microscopy revealed both 80- and 20-nm-diameter viral particles, which were consistent with adenoviruses and dependoviruses, respectively. Adenoviral outbreaks in groups of animals are uncommon. An adverse synergistic effect of the coccidiosis with the adenoviral infection may have played a critical role in the high morbidity and mortality in this case. 相似文献
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Early lesions of proliferative enteritis in pigs and hamsters 总被引：4，自引：0，他引：4
Gnotobiotic pigs and conventional hamsters were given suspensions of intestinal mucosa from a pig with proliferative hemorrhagic enteropathy and killed 10 or 21 days later. Affected animals had evidence of marked proliferation of immature enterocytes in the intestinal crypts. Numerous Campylobacter-like organisms were in the cytoplasm of enterocytes, and in some instances, bacteria were closely associated with enterocytes. Some intracellular bacteria lying below the microvillous border were within membrane-bound structures. Immunofluorescence and electron immunogold staining with specific antibodies indicated that these organisms were antigenically different from curved bacteria in the crypt lumen of early lesions. This study indicates that the life cycle of the intracellular organisms may involve entry into crypt enterocytes from the intestinal lumen with subsequent intracellular multiplication. 相似文献
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J C Nietfeld D E Tyler L R Harrison J R Cole K S Latimer W A Crowell 《American journal of veterinary research》1992,53(9):1493-1499
Porcine small intestinal explants maintained in vitro were inoculated with Salmonella choleraesuis to study the characteristics of its invasion of enterocytes. The explants were fixed at selected intervals for up to 12 hours after inoculation and examined by conventional light microscopy, immunoperoxidase staining, and transmission electron microscopy. Although there was diffuse loss of villous enterocytes during the first hour of incubation, the villi were reepithelialized by the end of 2 hours of culture, and the mucosal epithelium remained intact and appeared to be viable through 12 hours of culture. Intraepithelial S choleraesuis were not detected before 6 hours after inoculation, but after 12 hours of incubation, bacteria were numerous within enterocytes. Ultrastructurally, penetration of the brush border by S choleraesuis resulted in focal loss of microvilli. Bacteria were endocytosed into membrane-bound vacuoles where most remained, but a few were free within the cytoplasm of enterocytes. Invasion of the explants closely resembled that described for live animal and cell culture models of Salmonella spp invasion. 相似文献
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Studies on the Mechanism of Diarrhoea Induced by Escherichia coli Heat-Stable Enterotoxin (STa) in Newborn Calves 总被引：2，自引：0，他引：2
Al-Majali AM Asem EK Lamar CH Robinson JP Freeman MJ Saeed AM 《Veterinary research communications》2000,24(5):327-338
Enterotoxigenic Escherichia coli (ETEC) produces a heat-stable enterotoxin (STa) that binds to and activates a putative intestinal receptor, guanylate cyclase, causing an increase in the intracellular levels of cyclic guanosine monophosphate (cGMP). Using flow cytometry and 125I-STa binding assays, we studied the distribution of STa-receptors on enterocytes isolated from different segments of the newborn calf's intestinal tract. We also investigated the effect of STa on the intracellular levels of cGMP and ion transport to the intestinal lumen. More STa-receptors were found on enterocytes prepared from the ileum than on enterocytes obtained from the other segments of the intestinal tract. Guanylate cyclase activity was higher in the ileum of STa-challenged calves than in the ileum of control calves. No changes were observed in the guanylate cyclase activity of the other intestinal segments of the STa-challenged and control calves. Na+ levels, as measured by atomic absorption spectroscopy, were significantly increased in the luminal contents of the ileum of STa-challenged calves, whereas serum Cl– levels were significantly lower in the STa-challenged calves than in control calves. This study supports previous observations on the role of guanylate cyclase in the initiation of STa-induced secretory diarrhoea and suggests that Na+/Cl– coupling may be the major mechanism for the loss of ions in the diarrhoeal response that is mostly induced in the ileum of newborn calves. 相似文献
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B. P. Willing A. G. Van Kessel 《Journal of animal physiology and animal nutrition》2009,93(5):586-595
To study microbial influence on intestinal development pertaining to nutrient digestion, two separate gnotobiotic experiments were performed, each with 16 piglets allocated to four treatment groups: germfree (GF), monoassociation with Escherichia coli, monoassociation with Lactobacillus fermentum or conventionalization with faecal bacteria (CV). Enzyme activity and gene expression of lactase phlorizin hydrolase (LPH) and aminopeptidase N (APN) were measured in isolated enterocytes, harvested on day 14, using specific substrates and quantitative PCR respectively. Enterocytes of CV pigs had reduced APN activity, but had increased gene expression relative to GF, making the specific activity:mRNA (A:G) ratio dramatically lower (p < 0.05). Similarly, LPH A:G ratio was significantly reduced (p < 0.05) in enterocytes of CV pigs as compared with GF. The results of co‐incubation of L. fermentum, E. coli and faecal bacteria with APN indicate a direct relationship between enzyme inactivation and specific A:G ratio in enterocytes. We conclude that enterocyte up‐regulation of APN expression occurs as either a direct response to microbial colonization or as a feedback mechanism in response to reduced enzyme activity through microbial degradation. This mechanism may play a role in ensuring effective competition of the host with the intestinal microbiota for available nutrients. 相似文献
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Heat-stable enterotoxin (STa) secretion from Enterotoxigenic Escherichia coli (ETEC) is crucial for the pathogenesis of diarrhea in both animal and human. The goal of this study was to investigate the
distribution of the STa-specific receptors in the newborn camel’s enterocytes and brush border membrane vesicles (BBMVs).
Flow cytometric analysis was used to investigate the density of STa-receptors on enterocytes and BBMVs prepared from anterior
jejunum, posterior jejunum, ileum, and colon. Strong density and affinity of STa-receptors was present on enterocytes and
BBMVs of the ileum compared to that in the other intestinal segments. It was concluded that the ileum is the major target
for STa action in newborn camels. 相似文献