ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694966

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

During fifty years weaning age of piglets decreased from, in former days, ten to twelve weeks till, nowadays, three to five weeks. Early weaned piglets frequently have diarrhea. When piglets had diarrhea after weaning, enterotoxigenic E. coli (ETEC) or rotavirus were generally detected in the faeces; however, they were also detected in faeces of piglets without diarrhea. So, other causal factors must be involved in the occurrence of diarrhea after weaning. Mortality, due to diarrhea, was associated with severe villus shortening and crypt deepening. Furthermore, weaning piglets was also associated with villus shortening and crypt deepening and giving supplementary feed during the suckling period was effective in preventing villus shortening after weaning. Giving piglets sow's milk immediately after weaning is also effective in preventing villus atrophy. As shown with a small intestine segment perfusion test weaning was also associated with a loss of net absorption in both uninfected and ETEC‐infected small intestine. The loss of net absorption was less in piglets that were given supplementary feed during the suckling period. Net absorption in the small intestine increased significantly one day after a rotavirus infection and decreased significantly after subsequent infection with ETEC. Function of the large intestine also influences the severity of diarrhea in just weaned piglets. It may be concluded that weaning piglets at an age of three to five weeks changes the flora, the morphology, and the function of the intestine; these changes together result frequently in diarrhea.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694967

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This review discuss some recent findings in the study of the regulation of the permeability of the intestinal epithelial layer. Comparison of electrical phenomena and transport of macromolecules suggests that secretory activity and increased transepithelial transport of macromolecules are related when secretion is mediated by the Ca2+and PKC dependend pathways. The transport of the macromolecules is via the transcellular and via the paracellular route. The barrier function of the intestinal epithelium may be diminished during nervous (acetylcholine)‐ and immuno‐(histaminc) mediated secretion. It is hypothesised that some bacterial toxins may also induce Ca2+and PKC dependent secretion and thereby can reduce the epithelial barrier. The cAMP and cGMP mediated secretion, which can be recognised by their long‐lasting transepithelial potential changes, are not coupled to increased transepithelial transport of macromolecules. Some forms of secretory diarrhea may therefore be related to the development of food‐allergy or inflammation.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694968

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

It is often stated that the gastrointestinal tract has a limited number of responses to pathogens. Entirely different agents can produce a similar histopathological reaction. However, the expression of the disease in man is very heterogeneous, it varies with the age of the subject and is to a certain extent genetically determined. For example, food allergy is frequent in childhood and not common in adulthood. The intestinal mucosa in the child with cows milk allergy shows a ‘flat’ mucosa, which may be indistinguishable of that observed in gluten sensitive entero‐pathy or coeliac disease. Subjects with other forms of food allergy may have a morphologically normal small intestinal mucosa, occasionally with increased IgE plasma cells and often only characterised by an increased intestinal permeability. An abnormal intestinal permeability is one of the hallmarks of an inflamed gut, however, subjects with a latent form of coeliac disease have an abnormal permeability only without overt signs of inflammation.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694969

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Short‐chain fatty acids (SCFA) are produced by microbial fermentation in the hindgut in considerable amounts. Most of the anions in hindgut contents are SCFA, mainly acetate, propionate and butyrate. SCFA are rapidly absorbed. Mechanisms involved in the transepithelial transport are discussed.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694970

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In pigs and humans, the nutrients starch, protein, fat and some minerals need to be digested prior to the terminal ileum for optimal use of these nutrients. In contrast, the non‐starch polysaccharides (NSP) are mainly fermented by microbes in the hindgut. Results of experiments in pigs showed that NSP negatively affected apparent digestion of protein, fat and some minerals. In addition, large amounts of fermented NSP increased the empty weight of the hindgut. Because tissue of organs like the intestinal tract are metabolically very active, it may have required more energy for maintenance, hence leaving less energy for growth. Despite all the negative effects as mentioned above, including NSP‐rich ingredients in pig diets also has quite a lot of advantages. Their energy supply can cover the energy requirements for maintenance. In addition, positive effects on the well‐being and health of pigs, and on the excretion of ammonia are claimed. In conclusion, in future pig diet formulation not only the nutritional aspects of NSP‐rich ingredients should be taken into account, but also their non‐nutritional aspects. This might be realized by developing nutrient based feed evaluation systems, rather than the energy based systems which are presently used.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694971

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effect of weaning on the absorptive capacity of the large intestine (LI) of weaned and unweaned pigs for short chain fatty acids (SCFA), sodium, potassium, and water has been determined by perfusion studies. Ligated loops were formed at four sites in the LI. In both groups the rate of absorption of SCFA, sodium and potassium was increased from the proximal to the distal sites, but this increase was not followed by an increase in the absorption of water. It is concluded that unweaned and weaned pigs can absorb SCFA and electrolytes immediately after weaning, but that a period of adaptation is required for the optimal absorption of water. This lower capacity for the absorption of water in the first two weeks after weaning makes the recently weaned pig vulnerable to a loss of fluid from the intestines.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694972

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effects of three bacterial pathogens on the villus architecture of small intestines and the role that bacterial virulence factors play in pathogenesis are described. Bacterial pathogens cause a spectrum of effects ranging from severe tissue damage to a lack of perceptible damage. EnterotoxigenicEscherichia coli,which cause acute and severe diarrhea, does so by producing potent toxins, but these toxins act by altering the biological activity in epithelial cells. However, the cells are not damaged. EnteropathogenicE. coliandSalmonella,on the other hand cause various degrees of tissue damage. As part of their pathogenesis, they employ a type III protein secretion system to orchestrate internal changes in target cells. The expression of many virulence related genes is tightly regulated and appears to be turned on in response to cues found in the intestinal tract. The consequences of this level of regulation also is discussed.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694973

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The anti‐adhesive properties of 23 specific monoclonal antibodies (MAbs) against the F41 adhesive fimbrial antigen of enterotoxigenicEscherichia coli(ETEC) were studied in brush border adhesion inhibition tests and haemag‐glutination inhibition tests with four F41‐positiveE. colistrains and purified F41 antigen. These MAbs recognize five epitope clusters, F41–1 to F41–5. It was proven that these epitope clusters were located on the 29 kDa F41 major fimbrial subunits.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694974

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

After oral administration of live oral vaccines COLIN‐FANT and MUTAFLOR prepared from non‐entero‐pathogenicE.colistrains, both strains colonized effectively the intestine in full‐term and preterm infants and remained for many weeks showing, that they were capable to establish themself as a resident strain in the infant's gut. The presence ofE.colistimulated significantly antibody production in gut, saliva and serum of colonized infants. An early induction of secretory IgA production is important particularly in formula‐fed infants, where it partly replaces the lacking immunoglobulin supplied with mother milk.

ISSN:0165-2176    

DOI:10.1080/01652176.1998.9694975

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor