Lectin histochemical characterisation of the porcine small intestine around weaning

The present study was undertaken to characterise the carbohydrate profile of the porcine small intestine using lectin histochemistry during the period from 3 days prior to weaning to 9 days post-weaning. A total of 56 piglets weaned at 4 weeks of age were included in the experiment. The most prominent changes in the glycosylation pattern were observed in the goblet cells. The highest lectin reactivity of the goblet cells in the crypts was observed 7 days post-weaning which suggests that the protective effect of the mucus layer against pathogenic bacteria is increasing during the postweaning period. The staining pattern of the apical membrane remained unchanged during the experimental period. This indicates that the glycosylation process in the goblet cells is rapidly inducible whereas changes in the glycosylation pattern of the apical membrane requires more time. The glycosylation pattern of both goblet cells and apical membrane differed between the positions of the small intestine. As glycoconjugates can act as attachment sites for microorganisms, these differences in the distribution of sugar residues may be one explanation for the site-specificity of certain pathogens.     

Granular mucosal lymphocytes in porcine small intestine

A subpopulation of purified, interepithelial lymphocytes from porcine small intestinal mucosa contained cytoplasmic granules. Toluidine blue staining revealed metachromatic granules in 13.64% (606/4,450) cells. The cells had scant organelles, a single large nucleus with obvious invagination of the nuclear membrane, and prominent chromatin. Each cell contained 1 to 10 cytoplasmic membrane-bound granules, 0.6 to 1.5 micron in diameter. These findings indicated that the granular mucosal lymphocytes are related morphologically to mucosal mast cells. The presence of serotonin in the granules, confirmed by the serotonin releasing test, provided functional evidence that granular mucosal lymphocytes are related to mucosal mast cells.     

Effect of heat-stable enterotoxin of Escherichia coli and theophylline on ion transport in porcine small intestine.

The effect of a heat-stable enterotoxin of Escherichia coli was compared with that of theophylline on ion transport in the pig jejunum, using both in vivo and in vitro techniques. The maximal electrical response to heat-stable enterotoxin was only one-half that of theophylline even though the magnitude of the net secretory response was similar. A net, active secretion of HCO3 was partially responsible for the secretory response induced by heat-stable enterotoxin, whereas theophylline induced an active secretion of chlorine which could account for the entire secretory response. Heat-stable enterotoxin elevated tissue cyclic guanosine monophosphate levels, whereas theophylline elevated both cyclic adenosine monophosphate and cyclic guanosine monophosphate. Cyclic guanosine monophosphate levels induced by heat-stable enterotoxin were markedly potentiated by theophylline. Results suggest that HCO3 secretion in the pig jejunum may be controlled by the cyclic guanosine monophosphate system and this system also activates a neutral secretory process which at high heat-stable enterotoxin doses accounts for the bulk of the net secretion observed. Conversely, the chlorine secretion elicited by theophylline is entirely electrogenic and is consistent with results obtained in other species.     

Surgical diseases of the small intestine.

Surgical disorders of the gastrointestinal tract of cattle occur occasionally, and veterinarians are challenged to determine an accurate diagnosis and treatment for these conditions. Although surgical diseases most commonly occur in the forestomachs (dislocated abomasum, reticuloperitonitis) and the colons (cecal dilatation), this article focuses on lesions in the small intestine (duodenum, jejunum, ileum).     

The early postnatal pattern of vesicle formation in different regions of the porcine small intestine

In the early postnatal period, the permeability of the piglet small intestine is high to compensate for the absence of trans-placental transfer of immunoglobulins during the fetal period. Vesicles, which mainly reflect the uptake of macromolecules and other colostral/milk components, were studied in three different regions of the small intestine – proximal, mid and distal – in a total of twelve piglets on day 0 (unsuckled and colostrums-fed), 2 and 6 (all suckled). Tissues were sampled and prepared for light microscopy (paraffin and cryo) and trans-electron microscopy. Different methods were applied to visualize cytoplasmatic subcellular components such as fat (Oil red O) and carbohydrates (PAS). Appearance and morphology of the epithelial vesicles were compared.

In the proximal region several small supranuclear and a single large subnuclear electron dense, eosinophilic and PAS+ vesicle were present. They disappeared after 2 days (gut closure) and on day 6 adult-looking epithelial cells were present. In the distal region of day 0 pigs digestion vesicles/flocculent vesicles were observed in the cytoplasma. The vesicles appeared empty but with eosinophilic, PAS+ and electron dense precipitations. The size and variation of these vesicles increased with age. Fat absorption increased markedly from day 2 to day 6.

The observations indicate that in general colostral absorption processes are initiated prenatally, persist after birth and in the distal region also after gut closure. Fat absorption increased after gut closure, and in the distal region the increase correlated with e.g. IgG absorption.     

Histopathological,histochemical and immunohistochemical findings of the small intestine in goats naturally infected by Trichostrongylus colubriformis

Gastrointestinal (GI) strongyle infection remains one of the main constraints to goat production worldwide. Samples of small intestine from 15 Syrian goats naturally infected with Trichostrongylus colubriformis were examined by routine histology, histochemistry and immunohistochemistry to describe the histological changes and the phenotypes of inflammatory cellular components of the mucosa. Results indicated that the immune response to infection by T. colubriformis was characterized by an increased rate of the severity of the histologic lesions, an increase rate of T cell lymphocytes recruitment to the intestinal mucosa and quantitative and qualitative changes in the histochemical composition of mucin in goblet cells.     

Electrophysiological characterization of electrolyte and nutrient transport across the small intestine in horses

The aim of this study was to characterize the transport mechanisms of electrolytes and nutrients across the jejunum of nine healthy horses electrophysiologically. The stripped mucosa was mounted in Ussing chambers and tissue conductances (G_t) and short circuit currents (I_sc) were continuously monitored. After blocking the sodium and potassium channels with amiloride, tetraethylammonium chloride (TEA) and barium, chloride secretion was stimulated by carbachol and forskolin. Subsequently, chloride channels were inhibited by 4,4′‐diisothiocyanato‐stilbene‐2,2′‐disulfonic acid, 5‐nitro‐2‐(3‐phenylpropylamino)benzoic acid, CFTR_inh‐172, N‐(2‐naphtalenyl)‐(3.5‐dibromo‐2.4‐dihydroxyphenyl)methylene glycine hydrazide (GlyH‐101) and glibenclamide and their dose–response effect was investigated. The response to glucose, l ‐alanine and glycyl‐l ‐glutamine was determined at two different mucosal pH values (pH 7.4 and 5.4 respectively). Mean basal I_sc was ?0.47 ± 0.31 μEq/cm²h and mean G_t was 22.17 ± 1.78 mS/cm². Amiloride and TEA did not alter the baseline I_sc. Barium, carbachol and forskolin significantly increased I_sc. Irrespective of the dose, none of the chloride inhibitors changed I_sc. All nutrients induced a significant increase in I_sc with the increase being significantly higher at pH 7.4 than at pH 5.4. In conclusion, there is evidence that chloride secretion in horses may be different from respective transport mechanisms in other species. The glucose absorption is suggestive of a sodium‐dependent glucose cotransporter 1. However, a decrease in luminal pH did not stimulate current response to peptides as shown for other mammals.     

Effects of indomethacin on Salmonella typhimurium- and cholera toxin-induced fluid accumulation in the porcine small intestine

The effect of the cyclooxygenase and prostaglandin E2 (PGE2) synthesis inhibitor, indomethacin, on the secretory responses induced by Salmonella serotype Typhimurium (ST) and cholera toxin (CT), in the porcine small intestine was investigated. ST (10(10) colony-forming units) and CT (56 micrograms) were instilled in tied-off intestinal loops in young anaesthetized pigs receiving intravenous indomethacin in a total dose of 7.5 mg/kg, or saline. The accumulated fluid in the loops and the luminal content of endogenous secretagogues PGE2 and 5-hydroxytryptamine (5-HT) were measured. ST induced fluid accumulation in the jejunum, whereas CT induced fluid accumulation in the jejunum and ileum. Indomethacin had no effect on the secretory responses. Indomethacin had a significant effect on the luminal content of PGE2 in jejunal ST and CT loops, whereas no effect of indomethacin was observed on the luminal content of 5-HT in ST and CT loops. In ST and CT loops, an increased content of PGE2 and 5-HT compared with test loops infused with Ringer's solution was observed. These results indicate that the porcine jejunal secretory response to ST and CT does not involve prostaglandins although indomethacin has an influence on the luminal release of PGE2 but not of 5-HT.     

Influence of weaning age on the villous height and disaccharidase activities in the porcine small intestine

Body weight gain after weaning is correlated with villous height and disaccharidase activity. This evidence suggests that the maintenance of the small intestinal structure and function after weaning is important for the growth of piglets. We demonstrated that the influence of weaning age was obtained by disaccharidase activities and villous height in eight sections of the porcine small intestine. Therefore, we designed three weaning ages (weaned at the ages of 14, 21 or 28 days) and the piglets were slaughtered after 7 or 14 days post‐weaning. The remaining suckling piglets were slaughtered at the age of 1, 7, 14, 21 and 28 days. Four piglets were slaughtered at each event; therefore, 44 piglets were used in this study. Villous height and disaccharidase activities were measured in each section of the small intestine. Early weaning such as that at 14 days had severe influence on villous and disaccharidase activities. In particular, weaning of 14‐day‐olds did not result in maltase activity at least 2 weeks post‐weaning. Accordingly, the weaning age of crossbred piglets is recommended to be at least 21 days or more on the basis of villous height and disaccharidase activity analyses.     

Microvascular circulation of the small intestine in horses.

The microvascular anatomic features of the small intestine was described by correlating results of microangiography, light microscopy, gross studies, and scanning electron microscopy of vascular replicas in 14 horses. After heparinization, the horses were euthanatized, a length of jejunum was transected, and blood was flushed free of the circulation, using isotonic NaCl solution. In six horses, the circulatory system was perfused with a modified radiopaque medium and evaluated radiographically. These sections were then evaluated by standard histologic methods. Sections from 8 horses were perfused with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. The marginal arterial arcade gives rise to vessels that enter the jejunum at the mesenteric angle. These vessels penetrated either directly, by branching and entering on both sides of the mesenteric angle, or supplying only 1 side of the mesenteric angle. All these vessels continued in the submucosa branching extensively, forming a submucosal plexus. This submucosal plexus supplied the tunica muscularis, tunica serosa, and the mucosa. Vessels within the 2 muscle layers ran parallel to the muscle fibers and, consequently, perpendicular to each other. The arterial supply to the mucosa penetrated the muscularis mucosae and branched to supply 2 mucosal capillary networks. An eccentrically placed arteriole penetrated the base of the villus and spiralled to the tip where it "fountained" into a mesh-like capillary network, which descended peripherally in the villus to drain via 1 to 3, but most commonly 2 venules. Venules from adjacent villi united and drained via the submucosal veins.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lesions in the small intestine of newborn pigs inoculated with porcine, feline, and canine coronaviruses

The infectivity and pathogenicity to newborn pigs of antigenically related coronaviruses from pigs (transmissible gastroenteritis virus; TGEV), cats (feline infectious peritonitis virus; FIPV), and dogs (canine gastroenteritis virus; CGEV) were studied by light, scanning electron, and immunofluorescence microscopy. Hysterectomy-derived, 12-hour-old pigs were orally given tissue culture or frozen preparations of 6 coronavirus strains (3 porcine, 2 feline, and 1 canine). The pigs were killed at regular intervals between 24 and 144 hours after exposure. Virulent TGEV and virulent FIPV produced necrosis of villous epithelium, resulting in villous atrophy in the jejunum and the ileum. Similar, but less extensive and severe lesions, were produced by the 4 other viruses. Coronaviral antigens were identified by immunofluorescence in villous epithelial cells of pigs that had been inoculated with virulent TGEV, attenuated TGEV, virulent FIPV, and tissue culture-adapted FIPV. In contrast, coronaviral antigens were not induced by the small plaque variant TGEV and virulent CGEV in the villous epithelium, but rather in cells of the lamina propria and crypt epithelium.     

A lectin histochemical study of the zygomatic salivary gland of adult dogs

Seven lectins (PNA, DBA, SBA, UEA I, LTA, WGA and ConA), conjugated with horseradish peroxidase, were used to characterize the glycosidic residues in the zygomatic gland of adult dogs. In some cases (PNA and DBA), lectin staining was preceded by neuraminidase digestion. The acinar and tubular cells produced glycoconjugates with different sugar residues, presenting binding sites for all of the lectins used. The apical surfaces of the cells lining the intra- and interlobular ducts were also stained by all the lectins. In contrast, the demilunar cells only reacted with the Neu-PNA sequence and Con A. Abbreviations: Neu, neuraminidase; see also Table I     

猪源肠道优良乳酸杆菌的筛选

1材料与方法 1．1试验材料 1．1．1乳酸杆菌 由实验室从猪肠道分离、鉴定和保存，共10株，分别编号为L01、L02……L10。     

Comparative lectin histochemical studies on taste buds in five orders of mammals

Although it has been reported that specific proteins are present to take charge in the gustation in the taste buds, there have been only a few reports on the distribution of glycoconjugates binding to glycoproteins on the cellular membranes of the taste cells. In the present study, therefore, binding patters of 24 biotinylated lectins were examined in the three types of lingual papillae in five species of mammals belonging to different orders: cow (artiodactyl), horse (perissodactyl), monkey (primate), dog (carnivore) and mouse (rodent). As the results, lectin binding patterns were different among circumvallate, foliate and fungiform papillae, among the cells of the taste buds, and among animal species. These findings suggest that the different binding patterns of the lectins in the taste papillae and taste bud cells may be involved in different sensitivities of taste among mammalian species.     

The distribution of immunoglobulin-containing cells in canine small intestine.

Peroxidase conjugated antisera to canine immunoglobulins G and A and to human immunoglobulin M, have been used to study the distribution of immunoglobulin-containing cells in the small intestine of the young and adult dog. At all levels of the small bowel of the adult dog, IgA:IgM:IgG cells have a 2:1:1 ratio while the greatest number of immunocytes is found in the duodenum and decreases towards the distal portion of the small intestine. The young puppy shows a predominance of IgM-containing cells in the small intestinal lamina propria during early life but the adult pattern of immunocyte distribution has been achieved by weaning.