Antibodies to Intestinal Microvillous Membranes

Kopp, William L.; Trier, Jerry S.; Mackenzie, Iain; Donaldson, Robert M.

doi:10.1084/jem.128.2.357

Cited by 10 publications

(3 citation statements)

References 14 publications

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“…The present schema for vitamin B1n absorption envisages the ingestion of vitamin B12 (actually coenzyme B12 bound to protein [10][11][12][13]), release from its protein bond as a result of proteolytic digestion in an acid medium, binding to intrinsic factor in the stomach or upper portion of the small bowel (14)(15)(16), passage down the small bowel, attachment of the IF-B12 complex to a specific receptor located in the brush border of the ileal epithelial cell (17)(18)(19)(20)(21), and eventual release of the vitamin into the portal circulation unaccompanied by IF (22,23). In addition a factor elaborated by the pancreas may be an obligatory requirement for optimal vitamin Bi2 absorption.…”

Section: Discussionmentioning

confidence: 99%

The Role of the Pancreas in Vitamin B12 Absorption: Studies of Vitamin B12 Absorption in Partially Pancreatectomized Rats

Toskes¹,

Deren²

1972

J. Clin. Invest.

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A iB S T R A C T The effect of partial pancreatectomy(80-90%,) on vitamin Bn absorption was studied in the rat. The absorption of 5 ng of^'Co-labeled vitamin B1u was significantly reduced from 70 ±2.5% (mean +SE) in control and sham-operated rats to 32 ±2.6% in partially pancreatectomized rats. Hog pancreatic extract (0.17 g/kg) improved vitamin B12 absorption from 30.0 to 61.0% in partially pancreatectomized rats but did not alter vitamin B,2 absorption in control rats. Chloramphenicol did not enhance vitamin B12 absorption in partially pancreatectomized rats with pancreatic extractimproved vitamin B12 malabsorption. The partially pancreatectomized rats with pancreatic extract-improved vitamin B12 malabsorption were sacrificed and the stomach and small bowel studied in vitro to further define the pathogenesis of the vitamin B12 malabsorption. Rat gastric intrinsic factor stimulated vitamin B12 uptake by intestinal sacs prepared from partially pancreatectomized rats 3.1-fold. Gastric intrinsic factor prepared from partially pancreatectomized rats was as effective in promoting vitamin B12 uptake by rat intestinal sacs as intrinsic factor prepared from control rats. These data indicate that partially pancreatectomized rats develop an abnormality in the absorption of labeled vitamin B12 which can be corected by pancreatic extract. The vitamin B12 malabsorption is due to neither an alteration in gastric intrinsic factor activity nor an impairment of the intrinsic factor-vitamin B12 receptor in the intestine. It is suggested that in the partially pancreatectomized rats the intrinsic factor-vitamin B12 complex exists in a form which is not available for absorption. INTRODUCTIONAlthough several patients with pancreatic exocrine insufficiency have been noted to poorly absorb vitamin B,2 the importance of normal pancreatic function for optimal vitamin Bi absorption is generally not appreciated 1-5). Furthermore, the pathogenesis of the observed vitamin B12 absorptive defect has not been clarified.The relationship between the pancreas and the intestinal absorption of vitamin B12 was studied by measuring the absorption of this vitamin in rats subjected to partial pancreatectomy. The results demonstrate (a) that the partially pancreatectomized rat has a defect in vitamin B12 absorption, (b) that the administration of hog pancreatic extract restores vitamin B12 absorption to normal, (c) that intrinsic factor extracted from the gastric mucosa -of partially pancreatectomized rats stimulates vitamin Bn absorption in vitro, and (d) that gastric intrinsic factor stimulates vitamin B12 uptake in gut sacs prepared from partially pancreatectomized rats. These data indicate that partially pancreatectomized rats develop a defect in vitamin B12 absorption which is due to neither an alteration in gastric intrinsic factor activity nor to an impairment of the intrinsic factor-vitamin B12 receptor in the intestine.

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Section: Discussionmentioning

confidence: 99%

The Role of the Pancreas in Vitamin B12 Absorption: Studies of Vitamin B12 Absorption in Partially Pancreatectomized Rats

Toskes¹,

Deren²

1972

J. Clin. Invest.

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“…Intestinal tissue segments approx. 0.5 cm in length were fixed in 10% (v/v) neutral buffered formalin for 4 h at room temperature and left in 30% (w/v) sucrose in water overnight at 4°C (Kopp et al, 1968). The segments were embedded in O.C.T.…”

Section: Immunoffuorescent Localizationmentioning

confidence: 99%

Characterization and localization of the putative ‘link’ component in rat small-intestinal mucin

Fahim

Specian

Forstner

et al. 1987

Biochemical Journal

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Rat intestinal mucin is polymerized by a putative 'link' component of Mr 118,000 that can be released from the native mucin by thiol reduction [Fahim, Forstner & Forstner (1983) Biochem. J. 209, 117-124]. To confirm that this component is an integral part of the mucin and independent of the mucin purification technique, rat mucin was purified in the present study by three independent techniques. In all cases, the 118,000-Mr component was released after reduction. The 118 kDa band was electroeluted from SDS/polyacrylamide gels and its composition shown to resemble closely that of the link component of human intestinal mucin [Mantle, Forstner & Forstner (1984) Biochem. J. 224, 345-354]. Carbohydrates were present, including significant (10 mol/100 mol) amounts of mannose, suggesting the presence of N-linked oligosaccharides. Monospecific antibodies prepared against the rat 118,000-Mr component established its tissue localization in intestinal goblet cells. Mucins subjected to SDS/polyacrylamide-gel electrophoresis and Western blots using the same antibody, established that the link components of rat and human intestinal mucin are similar antigenically. Brief exposure (10 min) of native rat mucin to trypsin or Pronase (enzyme/mucin protein, 1:500, w/w) also released a 118,000-Mr component that reacted with the monospecific antibody. Thus the 118,000-Mr component is an integral part of the mucin and, although linked to large glycopeptides by disulphide bonds, this component also has proteinase-sensitive peptide bonds, presumably at terminal locations such that brief treatment with proteinases releases the molecule in a reasonably intact form. Under physiological conditions, therefore, one might expect that, after mucin is secreted into the intestinal lumen, luminal proteinases would rapidly remove the link component, thereby causing the mucin to depolymerize.

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“…Many short-term experiments (2 hr or less) have been satisfactorily conducted by maintaining open intestinal segments or everted rings and sacs of intestinal tissue in suitable oxygenated buffer solutions (1,2). Careful morphological studies have shown that epithelial cell integrity is maintained in these short-term experiments (3)(4)(5). However, marked epithelial cell necrosis and disintegration occurs if incubation of intestinal tissue is prolonged much beyond 2 or 3 hr.…”

Section: Introductionmentioning

confidence: 99%

Organ culture of mucosal biopsies of human small intestine

Browning¹,

Trier²

1969

J. Clin. Invest.

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344

134

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A B S T R A C T In vitro experiments of small intestinal mucosal function and metabolism utilizing excised tissue have been limited to a few hours by rapid epithelial cell necrosis which occurs with current incubation methods. We describe a method for culturing human mucosal biopsies for up to 24 hr employing organ culture methodology and demonstrate its potential application to studies of mucosal function. Peroral biopsies were placed in organ culture plates and maintained with modified Trowell's medium in 95% 0-5% C02 at 370C for 6-24 hr. To study cell proliferation, 2 uc of thymidine-'H was added per ml of medium. To

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Antibodies to Intestinal Microvillous Membranes

Cited by 10 publications

References 14 publications

The Role of the Pancreas in Vitamin B12 Absorption: Studies of Vitamin B12 Absorption in Partially Pancreatectomized Rats

The Role of the Pancreas in Vitamin B12 Absorption: Studies of Vitamin B12 Absorption in Partially Pancreatectomized Rats

Characterization and localization of the putative ‘link’ component in rat small-intestinal mucin

Organ culture of mucosal biopsies of human small intestine

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