INTESTINAL FUNCTION AFTER MASSIVE RESECTION OF THE SMALL INTESTINE IN A NEWBORN.
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Congenital Abnormalities↗
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Phenylalanine transport in rabbit small intestine.
1. The proposal that rabbit small intestine possesses a separate, sodium-dependent carrier of phenylalanine has been examined by measurements of the unidirectional influx of amino acids across the brush-border membrane of the intact epithelium of the rabbit small intestine. 2. We demonstrate that, like alanine, glycine and leucine, phenylalanine shares sodium-dependent as well as sodium-independent transport with lysine. 3. Using the distal ileum we applied the A (phenylalanine)-B (leucine)-C (alanine) test on the sodium-dependent, lysine-resistant transport of phenylalanine. For phenylalanine, K1/2 (concentration required for half-maximal transport) was 3.1 +/- 0.2 mM (n = 7) and Ki (inhibitor constant) against leucine transport was 3.1 +/- 0.2 mM (n = 4). For leucine, K1/2 was 1.1 +/- 0.1 mM (n = 4) and Ki against transport of phenylalanine was 1.1 +/- 0.1 mM (n = 4). For alanine, K1/2 was 12.6 +/- 1.1 mM (n = 3), Ki against phenylalanine was 13.1 +/- 1.8 mM (n = 4) and Ki against leucine was 11.0 +/- 0.4 mM (n = 4). 4. Using the jejunum we applied the A (phenylalanine)-B (alanine)-C (methionine) test on the lysine-resistant, sodium-dependent transport of phenylalanine. For phenylalanine, K1/2 was 4.7 +/- 0.2 mM (n = 7) and Ki against alanine was 4.8 +/- 0.2 mM (n = 4). For alanine, K1/2 was 15.6 +/- 0.8 mM (n = 7) and Ki against phenylalanine was 18.1 +/- 0.9 mM (n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)
Alanine↗
Measurement of electrical activity of the human small intestine using surface electrodes.
Electrical activity of the human small intestine is usually measured by implanted or intraluminal electrodes. The application of these invasive techniques is, however, very limited. In this paper, a noninvasive technique is introduced to measure electrical activity of the small intestine by placing electrodes on the abdominal skin over the small intestine. Surface recordings were obtained in ten healthy volunteers, three patients with total gastrectomy and five patients with gastroparesis (a slight degree of paralysis of the mucosal coat of the stomach) with implanted electrodes on the serosa of the duodenum. An omnipresent 9-12 cpm electrical activity was observed in all surface recordings. Our findings from the surface electrodes were consistent with those reported in the literature via implanted or intubated electrodes. It is concluded that the technique described in this paper provides a noninvasive way to measure electrical activity of the small intestine. It may have potential application in medical research and clinical diagnosis.
Adult↗
Small intestinal bacterial overgrowth and enhanced intestinal permeability in healthy beagles.
The small intestine of healthy adult Beagles was examined to determine whether subclinical abnormalities might exist that would be relevant to the use of Beagles in pharmacologic studies. Duodenal juice was obtained for qualitative and quantitative bacteriologic examinations; jejunal mucosa was taken for morphologic and biochemical investigation, and intestinal permeability was assessed by quantification of 24-hour urinary excretion of 51Cr-labeled EDTA after its oral administration. Comparisons were made with findings in healthy adult dogs of other breeds that served as controls. Small intestinal bacterial overgrowth was found in 14 of the 21 Beagles examined, and represented a mixed flora that included obligate anaerobic bacteria in 8 dogs and exclusively aerobic bacteria in 6 dogs. Intestinal permeability (percentage urinary recovery of 51Cr-labeled EDTA; mean +/- SEM) was considerably higher (P < 0.01) in Beagles with anaerobic overgrowth (37.6 +/- 3.2%) or aerobic overgrowth (30.5 +/- 4.8%), compared with Beagles with no overgrowth (17.3 +/- 1.6%) and with controls (11.1 +/- 1.0%). In Beagles, significant (r = 0.54, P = 0.03) correlation was observed between 24-hour urinary recovery of 51Cr-labeled EDTA and bacterial numbers in duodenal juice. Morphologic changes in jejunal mucosa were minimal, and specific activities of brush border enzymes were not significantly decreased, apart from aminopeptidase N, but activities of lysosomal and endoplasmic reticular marker enzymes were higher in the 3 groups of Beagles with anaerobic, aerobic, or no overgrowth, compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Expression of apolipoprotein B-100 in isolated human small intestine epithelium.
Apolipoprotein B-48 (apoB48) is synthesized in the small intestine and becomes a component of chylomicrons (CM). Apolipoprotein B-100 (apoB100) is synthesized in liver and becomes a component of both very low density lipoprotein (VLDL) and low density lipoprotein (LDL). To evaluate whether apoB100 is present in the human small intestine, we performed immunohistochemical staining using anti-apoB100 monoclonal antibody (mAb). Jejunal samples stained positive and the granular staining was noted in the supranuclear region of epithelial cells. We also identified apoB100 expression in the epithelial cells by immunoblotting and dot-blotting of PCR-amplified cDNA. In order to exclude submucosal stroma contaminated with blood, we used isolated epithelium from human small intestine obtained by a crypt isolation technique. The results indicate that not only apoB48, but also apoB100 are expressed in human small intestine epithelium. The expression of apoB100 suggests that the dietary VLDL may be synthesized in human small intestine epithelium and converted into LDL, which might play an important role in atherosclerosis.
Apolipoprotein B-100↗
Paneth cell alpha-defensins from rhesus macaque small intestine.
Antimicrobial peptides are secreted by small intestinal Paneth cells as components of innate immunity. To investigate the role of alpha-defensins in enteric host defenses in nonhuman primates, alpha-defensin cDNAs were isolated, alpha-defensin peptides were purified from rhesus macaque small bowel, and the bactericidal activities of the peptides were measured. Six rhesus enteric alpha-defensin (RED) cDNAs, RED-1 to RED-6, were identified in a jejunum cDNA library; the deduced RED peptides exhibited extensive diversity relative to the primary structures of rhesus myeloid alpha-defensins. RED-4 was purified from monkey jejunum, and N-terminal peptide sequencing of putative RED-4 peptides identified two N termini, RTCYCRTGR. and TCYCRTGRC.; these corresponded to alternative N termini for the RED-4 molecules, as deduced from their molecular masses and RED cDNAs. In situ hybridization experiments localized RED mRNAs exclusively to small intestinal Paneth cells. Recombinant RED-1 to RED-4 were purified to homogeneity and shown to be microbicidal in the low micromolar range (</=10 micro g/ml) against gram-positive and gram-negative bacteria, with individual peptides exhibiting variable target cell specificities. Thus, compared to myeloid alpha-defensins from rhesus macaques, enteric alpha-defensin peptides are highly variable in both primary structure and activity. These studies should facilitate further analyses of the role of alpha-defensins in primate enteric immunity.
Amino Acid Sequence↗
Injectable small intestinal submucosa: preliminary evaluation for use in endoscopic urological surgery.
PURPOSE: We evaluated the possible use of small intestinal submucosa in endoscopic urological surgery by assessing the smooth muscle regenerative capabilities and physical response of various forms of injectable small intestinal submucosa in the canine model. MATERIALS AND METHODS: In blinded fashion we injected small intestinal submucosa in 12 dogs submucosally under direct vision using a 20 gauge endoscopic needle. The 4 small intestinal submucosa formulations varied in harvesting method and sterilization technique. Animals were divided into groups of 3 and sacrificed 2 weeks, 6 weeks, 3 months and 6 months after surgery. Each injection site was analyzed grossly and histologically. Smooth muscle regeneration was identified by alpha-smooth muscle actin immunohistochemical staining. RESULTS: We identified 2 injectable small intestinal submucosa formulations that induced progressive smooth muscle regeneration at the site of submucosal injection compared with controls. De novo smooth muscle cells appeared in single cell aggregates as early as 6 weeks and in globular aggregates at 3 months. By 6 months early muscle bundle formation was noted. These 2 injectable small intestinal submucosa formulations also had the best submucosal volume preservation of about 25% of injected material during the study period. CONCLUSIONS: Injectable small intestinal submucosa promotes progressive submucosal smooth muscle regeneration in the canine bladder. The combined regenerative and bulking abilities of injectable small intestinal submucosa make this compound unique and novel. The clinical usefulness of injectable small intestinal submucosa for endoscopic correction of reflux and incontinence deserves further investigation.
Animals↗
[Morphofunctional changes in the small intestine in patients with chronic cardiac failure].
AIM: To study morphological alterations in small intestinal wall in patients with chronic cardiac failure (CCF) of various severity and their relations with functional condition of the small intestine. MATERIAL AND METHODS: 63 patients (mean age 58.7 years) entered an open cohort study. By CCF and body mass index (BMI) the patients were divided into 4 groups. Estimation of ejection fraction (EF), BMI and lean body mass (LBM) was made in all the patients as well as functional intestinal activity was assessed by fat excretion and fecal protein. Small intestinal biopsies were made endoscopically for collagen quantitation. RESULTS: A rise in collagen content in the small intestine correlated with severity of CCF. In patients free of CCF relative area of collagen averaged 12.8%, in CCF FC I-II--16.5%, in CCF FC III-IV with cachexia--32.4%. Greater fibrosis of the small intestine corresponded to greater malabsorption. A 3-fold increase in collagen area led to a 2-3-fold growth in protein and fat loss with feces. In CCF, LBM was subnormal while body mass reduction correlated with relative collagen area. CONCLUSION: Morphofunctional changes of the small intestine developing in parallel with CCF severity lead to a significant loss in basic nutrients, regression of LBM and development of protein-energy insufficiency in patients with CCF.
Cardiac Output, Low↗
Characterization of lipid exchange proteins isolated from small intestinal brush border membrane.
Subjecting rabbit small intestinal brush border membrane vesicles (BBMV) to freeze-thaw cycles releases water-soluble lipid exchange (transfer) proteins into the supernatant. They differ widely in apparent molecular weight and catalyze cholesterol, phosphatidylcholine, and phosphatidylinositol exchange between two populations of small unilamellar lipid vesicles. In order to determine their interrelations, the smallest water-soluble lipid exchange protein was purified to homogeneity by gel filtration on Sephadex G-75 and cation exchange chromatography on Mono S. It is a basic protein of apparent molecular mass of 13 +/- 0.5 kDa. The purified protein was used to raise polyclonal antibodies. Polyclonal antibodies were also produced against a lipid exchange protein of apparent molecular mass of 100-120 kDa. By comparing lipid exchange, lipid binding, and immunological properties of the water-soluble lipid exchange proteins it can be shown that the 13-kDa (peak 3) protein is related to the 100-120 kDa (peak 1) protein; the properties of these two proteins are different from those of the peak 2 lipid exchange protein of apparent molecular mass of 22 kDa. Based on the immunological cross-reactivity observed between the 13 and 100-120 kDa and the lipid binding properties of these two proteins, a working hypothesis is proposed: both proteins are probably part of an integral membrane protein of the brush border membrane that facilitates cholesterol and phosphatidylcholine absorption in this membrane. Evidence derived from immunogold labeling of BBMV supports the notion that this protein is located on the external (luminal) side of the brush border membrane. The analogous behavior of rabbit and human small intestinal brush border membrane in terms of lipid absorption and the release of water-soluble lipid exchange proteins is discussed.
Animals↗
Utility of lavage alkaline phosphatase in detection of isolated small intestinal injury.
The ability of lavage alkaline phosphatase (LAP) to detect small intestinal injury was studied in 81 patients who underwent diagnostic peritoneal lavage following blunt and penetrating abdominal trauma. Patients with a grossly positive lavage were excluded. The LAP of five patients with small intestinal injury (79.0 +/- 41.7 IU/L) was significantly greater than in 76 cases without (1.2 +/- 0.4 IU/L; P less than .05). LAP greater than or equal to 3 was seen in six patients. Four had isolated small intestinal pathology, and one had combined small and large bowel injury. In three of these five, other lavage values were normal. One possible false positive occurred. The sensitivity of LAP greater than or equal to 3 (100%) exceeded that of usual lavage parameters in the detection of small intestinal injury. LAP may be a sensitive marker for small intestinal pathology in the immediate postinjury period.
Adolescent↗
Comparison of the 1-gram (14)C-D-xylose breath test and the 50-gram hydrogen glucose breath test for diagnosis of small intestinal bacterial overgrowth.
BACKGROUND/AIMS: Culture of small bowel aspirate is the most direct method and the gold standard for diagnosing small intestinal bacterial overgrowth. However, cultures are cumbersome and fluoroscopy is required for obtaining aspirate. Therefore, different breath tests such as the xylose breath test and the hydrogen breath test have been developed. There is no general agreement as to which test is to be preferred. In the only previous direct comparison between these two tests an advantage for the 1-gram-(14)C-D-xylose breath test was found. The aim of the study was to compare the 50-gram glucose hydrogen breath test and the 1-gram (14)C-D-xylose breath test in relation to results of cultures of small bowel aspirate. METHODS: Forty-six consecutive patients, mean age 57 (range 27-87) years, 12 men and 34 women, were included because of suspicion of small intestinal bacterial overgrowth. After small bowel aspiration, all patients received a solution of 1 g xylose, labelled with 50 microg (14)C-D-xylose, and 50 g glucose dissolved in 250 ml water. The concentration of breath hydrogen was analyzed every 15 min for 2 h and (14)CO(2) was analyzed every 30 min for 4 h. A positive hydrogen breath test was defined as a rise in hydrogen concentration of 15 ppm. A positive xylose test was defined as an accumulated dose 4.5% after 4 h. Two definitions for a positive culture were used, either growth of 10(5 )colonic-type bacteria/ml or growth of 10(5) bacteria/ml of any type. RESULTS: Twenty-four patients had growth of 10(5) bacteria, of whom 10 had growth of 10(5) colonic-type bacteria in small bowel aspirate. Twenty-two patients had no significant growth. The hydrogen breath test and the xylose breath test had a sensitivity for growth of 10(5) bacteria of 58 and 42%, respectively. For growth of 10(5 )colonic-type bacteria the sensitivity was 90% for the hydrogen breath test and 70% for the xylose breath test. The specificity was similar for the two tests. CONCLUSION: Although no significant difference between the two tests was found, there was a tendency in favor of the 50-gram glucose hydrogen breath test. The simplicity in combination with high sensitivity makes the hydrogen breath test suitable as a screening method to select patients for further investigation.
Adult↗
Electroneutral sodium absorption and electrogenic anion secretion across murine small intestine are regulated in parallel.
Electrolyte transport processes of small intestinal epithelia maintain a balance between hydration of the luminal contents and systemic fluid homeostasis. Under basal conditions, electroneutral Na(+) absorption mediated by Na(+)/H(+) exchanger 3 (NHE3) predominates; under stimulated conditions, increased anion secretion mediated by CFTR occurs concurrently with inhibition of Na(+) absorption. Homeostatic adjustments to diseases that chronically affect the activity of one transporter (e.g., cystic fibrosis) may include adaptations in the opposing transport process to prevent enterosystemic fluid imbalance. To test this hypothesis, we measured electrogenic anion secretion (indexed by the short-circuit current) across NHE3-null [NHE3(-)] murine small intestine and electroneutral Na(+) absorption (by radioisotopic flux analysis) across small intestine of mice with gene-targeted disruptions of the anion secretory pathway, i.e., CFTR-null [CFTR(-)] or Na(+)-K(+)-2Cl(-) cotransporter-null [NKCC1(-)]. Protein expression of NHE3 and CFTR in the intestinal epithelia was measured by immunoblotting. In NHE3(-), compared with wild-type small intestine, maximal and bumetanide-sensitive anion secretion following cAMP stimulation was significantly reduced, and there was a corresponding decrease in CFTR protein expression. In CFTR(-) and NKCC1(-) intestine, Na(+) absorption was significantly reduced compared with wild-type. NHE3 protein expression was decreased in the CFTR(-) intestine but was unchanged in the NKCC1(-) intestine, indicating that factors independent of expression also downregulate NHE3 activity. Together, these data support the concept that absorptive and secretory processes determining NaCl and water movement across the intestinal epithelium are regulated in parallel to maintain balance between the systemic fluid volume and hydration of the luminal contents.
Animals↗
Absence of vacuolar H+-ATPases from rat small intestine brush-border membranes.
Rat small intestinal brush-border membrane (BBM) vesicles were solubilized to test for the presence of an intravesicular H+-ATPase. Several detergents that in rat renal BBM vesicles revealed a bafilomycin-sensitive H+-ATPase failed to expose a similar ATPase in small intestinal vesicles. Antibodies against the 31-kDa and 70-kDa H+-ATPase subunits labelled respective antigens in the BBM of renal proximal tubules, but not in the BBM of enterocytes. The results demonstrate that a bafilomycin-sensitive, vacuolar-type H+-ATPase is absent from the BBM of enterocytes and, hence, cannot contribute to H+ secretion.
Animals↗
Identification of extractable growth factors from small intestinal submucosa.
When implanted as a biomaterial for tissue replacement, selected submucosal layers of porcine small intestine induce site-specific tissue remodeling. Small intestinal submucosa (SIS), as isolated, is primarily an acellular extracellular matrix material. In an attempt to discover the components of small intestinal submucosa which are able to induce this tissue remodeling, the material was extracted and extracts were tested for the ability to stimulate Swiss 3T3 fibroblasts to synthesize DNA and proliferate. Each of the four different extracts of small intestinal submucosa had measurable cell-stimulating activity when analyzed in both a whole cell proliferation assay (alamarBlue dye reduction) and a DNA synthesis assay ([3H]-thymidine incorporation). Proteins extracted from SIS with 2 M urea induced activity profiles in the two assays which were very similar to the activity profiles of basic fibroblast growth factor (FGF-2) in the assays. As well, the changes in cell morphology in response to the extracted proteins mimicked the changes induced by FGF-2. Neutralization experiments with specific antibodies to this growth factor confirmed the presence of FGF-2 and indicated that it was responsible for 60% of the fibroblast-stimulating activity of the urea extract of small intestinal submucosa. Western blot analysis with a monoclonal antibody specific for FGF-2 detected a reactive doublet at approximately 19 kDa and further confirmed the presence of FGF-2. Cell stimulating activity of proteins extracted from SIS with 4 M guanidine was neutralized by an antibody specific for transforming growth factor beta (TGF beta). Changes in the morphology of the fibroblasts exposed to this extract were nearly identical to changes induced by TGF beta. Although no reactive protein band was detected at 25 kDa in nonreduced western blot analysis, several bands were reactive at higher molecular weight. The identity of this TGF beta-related component of small intestinal submucosa is unknown. Identification of FGF-2 and TGF beta-related activities in SIS, two growth factors known to significantly affect critical processes of tissue development and differentiation, provides the opportunity to further elucidate the mechanisms by which this extracellular matrix biomaterial modulates wound healing and tissue remodeling.
3T3 Cells↗
Regulation of active ion transport in the small intestine.
The epithelium of the small intestine can both actively absorb and actively secrete electrolytes and water. Secretion can be elicited in vitro by adding cyclic AMP or a stimulator of intestinal mucosal adenylate cyclase (cholera and Escherichia coli enterotoxins, prostaglandins, vasoactive intestinal peptide) or an inhibitor of cyclic AMP phosphodiesterase (theophylline). Cyclic AMP appears to alter intestinal ion transport at two different loci: it inhibits a coupled influx process for Na+ and Cl- at the luminal border, thereby reducing active absorption of NaCl, and it also stimulates the active secretion of anion (or Na+ and anion). A variety of evidence suggests that these two effects of cyclic AMP reside in different types of cells, the former in villus cells and the latter in crypt cells. The latter process is Na+-dependent and is inhibited by low concentrations of ouabain and ethacrynic acid. Active ion absorption in vitro can be enhanced by (1) stimulating Na+-coupled organic solute absorption with glucose, amino acids and possibly also oligo peptides; (2) reducing the HCO3- concentration and/or pH of the serosal bathing solution; and (3) introducing an alpha-adrenergic agonist. Cholera toxin-induced fluid production in vivo can be diminished by the first of these manoeuvres. The in vivo efficacies of the other two have not been evaluated.
Animals↗
Tyrosine sulfation, a post-translational modification of microvillar enzymes in the small intestinal enterocyte.
Protein sulfation in small intestinal epithelial cells was studied by labelling of organ cultured mucosal explants with [35S]-sulfate. Six bands in SDS-PAGE became selectively labelled; four, of 250, 200, 166 and 130 kd, were membrane-bound and two, of 75 and 60 kd, were soluble. The sulfated membrane-bound components were all enriched in the microvillar fraction but either absent or barely detectable in intracellular or basolateral membranes. Immunopurification of sucrase-isomaltase, maltase-glucoamylase, aminopeptidase N and aminopeptidase A showed that these microvillar enzymes become sulfated. Most if not all the sulfate was bound to tyrosine residues rather than to the carbohydrate of the microvillar enzymes, showing that this type of modification can occur on plasma membrane proteins as well as on secretory proteins.
Alkaloids↗
Characterization of the muscarine receptors involved in the modulation of serotonin release from the vascularly perfused small intestine of guinea pig.
Isolated small intestinal segments of the guinea pig were arterially perfused and the release of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) into the portal venous effluent measured by HPLC with electrochemical detection. Test substances were applied via the arterial perfusion medium. McN-A-343, pilocarpine and oxotremorine inhibited concentration-dependently the outflow of 5-HT and 5-HIAA. Pirenzepine (0.03-0.1 mumol/l) which can discriminate between M1 and M2-receptor subtypes antagonized completely this inhibitory effect. In the presence of 1 mumol/l tetrodotoxin (TTx), all three muscarine receptor agonists increased the outflow of 5-HT and 5-HIAA. Oxotremorine (1 mumol/l) was most effective and increased the outflow of 5-HT by 145%, that of 5-HIAA by 235%. McN-A-343 and pilocarpine, both at a concentration of 10 mumol/l, increased the outflow of 5-HT by about 40%, that of 5-HIAA by 50% and 71%, respectively. The stimulatory effect of oxotremorine was competitively antagonized by pirenzepine; a pA2 value of 7.70 was calculated. In conclusion, the cholinergic modulation of the release of 5-HT from the enterochromaffin cells consists of an indirect inhibitory (via the release of a neurotransmitter) and a direct stimulatory component. Muscarine receptors mediating the indirect effect may belong to the M1-subtype whereas the direct stimulatory effect may be mediated by a mixed population of M1 and M2 receptors or by a subtype of M1 receptors.
(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
Shapes and projections of tertiary plexus neurons of the guinea-pig small intestine.
The axons of neurons that innervate the longitudinal muscle of the small intestine in small mammals such as rabbit, rat, guinea pig and mouse form a network, the tertiary plexus, against the inner surface of the muscle. In general, because of their substantial overlap, it has not been possible to follow the ramifications of individual axons in the tertiary plexus. In the present work, the longitudinal muscle motor neurons were filled with marker dyes through an intracellular microelectrode, and their morphologies and projections were examined in whole-mount preparations of longitudinal muscle and myenteric plexus. Most neurons that were examined were in the small intestine (ileum and duodenum), but a few were examined in the distal colon. Neurons in all regions had similar morphologies and projections. The cell bodies were amongst the smallest in myenteric ganglia, with major and minor axes of 14 microns and 25 microns (mean, n = 40) in the plane of the myenteric plexus. Each neuron had a single axon that branched extensively in the tertiary plexus, most had multiple lamellar dendrites and a few had filamentous dendrites or a mixture of filamentous and lamellar dendrites. The mean area of muscle covered by an axon and its branches extended 1.6 mm orally to anally and 1.7 mm circumferentially. The area covered was 2.8 +/- 1.9 mm2 (mean +/- SD, n = 23). From the density of occurrence of cell bodies, it can be calculated that each point in the longitudinal muscle is innervated by the processes of about 100 motor neurons and is influenced by electrotonic conduction of signals through the muscle by about 300 motor neurons.
Animals↗