Intrinsic Factor In Gastric Juice Research Articles

Absence of luminal intrinsic factor after gastric bypass surgery for morbid obesity.

Abnormally low serum cobalamin levels (less than 180 pg/ml) have been observed in 154 of 429 patients (36%) at an average of 22 months (range 3-64 months) after gastric bypass surgery for morbid obesity. Twenty-four patients underwent a Schilling test and retrograde endoscopy of the bypassed gastric segment to determine the presence of intrinsic factor (IF) in gastric aspirates and in mucosal biopsies at 22 +/- 4 months after surgery. Five patients had a normal cobalamin level (405 +/- 44 pg/ml), and gastric juice intrinsic factor was present in three of them (11 +/- 7 ng/ml). Nineteen patients had a low cobalamin level (113 +/- 8 pg/ml), and gastric juice IF was found in only two subjects of this group (10 ng/ml each). Basal gastric juice IF concentration of healthy control subjects was 24 +/- 5 ng/ml. Schilling test results were normal in all five patients of the first group and in only nine patients of the group with cobalamin deficiency after surgery. To assess whether IF was present within the parietal cells of subjects with absent luminal IF, we studied gastric biopsy material of 14 patients using a well-characterized indirect immunoperoxidase method. IF was identified in fundic mucosal biopsy specimens of all 14 patients with absent gastric juice IF. We conclude that cobalamin deficiency occurs in a significant number of patients after gastric bypass and is associated with absence of gastric juice IF. We propose that this abnormality might be caused by inadequate secretion of IF from the bypassed stomach.

Biochemistry and clinical chemistry of vitamin B 12 transport and the related diseases

This review focusses on research performed by the author and coworkers. The absorption, turnover and excretion of cobalamin and the pathogenesis of cobalamin deficiency states are described and the laboratory tests used to diagnose these states are discussed. Topics dealt with in detail include: overall turnover, daily need, enterohepatic circulation and excretion of cobalamin and other corrins . The soluble proteins mediating cobalamin transport and their cellular receptors are described and their nomenclature, isolation, structure and mode of action, the role of calcium in the membrane transport, the evolution of these systems and the analogies with transport systems for other substrates are discussed together with deficiency states, especially fish tapeworm anemia and familial selective vitamin B12 malabsorption with proteinuria. Folate deficiency is a relatively rare cause of megaloblastic anemia in Scandinavia but common in North America and explanations for this difference are suggested. The methods of assaying cobalamin in serum and plasma and the performance of radiovitamin B12 absorption tests are critically evaluated. The measurement of intrinsic factor in gastric juice, serum, amniotic fluid and urine is described.

Functional activity of intrinsic factor measured by using solubilized receptor protein.

The traditional radioimmunoassay for gastric intrinsic factor, in which this protein is measured on the basis of immunoreactivity rather than function, is of no value for identifying intrinsic factor that binds cobalamin but does not bind to the ileal receptor site, or for detecting animal intrinsic factor, which does not cross react with human intrinsic factor. Accordingly, we have applied a radioassay for the intrinsic factor receptor protein to measure the functional activity of intrinsic factor in gastric juice. The receptor protein reagent was partly purified from guniea pig ilea and its interaction with intrinsic factor--CN[57Co]-cobalamin was determined by precipitation with sodium sulfate at a final concentration of 150 g/L. Results of this assay were comparable with results obtained for intrinsic factor by radioimmunoassay. The receptor protein did not bind immunoreactive intrinsic factor that was functionally abnormal. This functional radioassay for intrinsic factor is not species specific and will be of value when specific antiserum to intrinsic factor is not available and when cobalamin malabsorption is to be evaluated in patients who are secreting normal amounts of immunoreactive intrinsic factor.

An assay for intrinsic factor based on blocking of the R binder of gastric juice by cobinamide

An in vitro assay for measurement of gastric juice intrinsic factor (IF) was developed based on the ability of the cobinamide (Cbi) [(CN, OH) Cbi] to bind to the gastric juice R-type binders of cobalamin (Cbl) and not to the IF binder. Subsequently added radioactive Cbl, CN-[57Co] Cbl, binds only to the IF binders and allows for direct measurement of this Cbl binding protein. This Cbi blocking assay was found to function as well as the more conventional methods of IF measurement, G-100 column chromatography, and IF blocking antibody assay. The present assay has the advantage of eliminating the need for elaborate forms of protein separation and does not rely on a source of antibody.

An Assay for Intrinsic Factor Based on Blocking of the R Binder of Gastric Juice by Cobinamide

An in vitro assay for measurement of gastric juice intrinsic factor (IF) was developed based on the ability of the cobinamide (Cbi) [(CN, OH) Cbi] to bind to the gastric juice R-type binders of cobalamin (Cbi) and not to the IF binder. Subsequently added radioactive Cbi, CN-[57Co] Cbi, binds only to the IF binders and allows for direct measurement of this Cbi binding protein. This Cbi blocking assay was found to function as well as the more conventional methods of IF measurement, G-100 column chromatography, and IF blocking antibody assay. The present assay has the advantage of eliminating the need for elaborate forms of protein separation and does not rely on a source of antibody.

Diabetes mellitus as analogue of pernicious anemia: a speculation.

DIABETES MELLITUS AS ANALOGUE OF PERNICIOUS ANEMIA: A SPECULATION JEROME D. GORMAN, MD* Power of nutriment reaches to bone and to all the parts of bone, to sinew, to artery, to muscle, to membrane, to flesh, fat, blood, phlegm, marrow, brain, spinal marrow, the intestines and all their parts; it reaches also to heat, breath, and moisture. [Hippocrates] There are more than a hundred, indeed more than a thousand, kinds of stomach; consequently, if you gather a thousand persons, each of them will have a different kind of digestion, each unlike the others. [Paracelsus] A speculative induction and deduction is presented regarding food and gut factors in diabetes mellitus and pernicious anemia. No proof or new facts are offered in the hypothesis which concentrates on similarities of form rather than differences in function. Pernicious Anemia Pernicious anemia has juvenile and adult forms [1-3]. In 1926, Minot and Murphy [4] reported therapeutic success with beef liver in pernicious anemia. Castle and Townsend [5] discovered gastric juice intrinsic factor. In 1948, crystalline vitamin B12 was isolated and its structure was determined in 1955. Diabetes Mellitus Diabetes mellitus also has juvenile and adult forms. Episodic hypoglycemia may precede fixed diabetes. Eclampsia, hypertension, and retinopathy occur more often in diabetics. Gepts [6] thought an extrapancreatic factor altered islet cell population as well as the number and size of pancreatic islets. Besides islet hormones, gastrointestinal and other hormones have glucoregulatory roles. * Address: 5713 Penguin Drive South West, Roanoke, Virginia 24018. Perspectives in Biology and Medicine · Winter 1973 I 323 Intersection An association between pernicious anemia and diabetes mellitus has been repeatedly noted. Hepatic dysfunction, gallstones, neuropathies , and polyendocrine and gastric autoantibodies occur in both diseases [7-12]. Discordance may appear in identical twins [13, 14]. Liver Extract In isolating the liver extract effective in pernicious anemia, Cohn et al. [15] found another that lowered blood pressure and still another with hypoglycemic effect. Levin [16] reported useful results in human diabetics given injections of beef-liver extract. Blotner and Murphy Blotner and Murphy [17, 18] compared blood-sugar response in diabetics who ate test meals containing equal amounts of protein (red muscle meat or raw calf liver), carbohydrate, and fat. The meal containing liver (or extracts thereof) was more hypoglycemic than the meal containing muscle (see table 1 and Appendix). Duodenal Extract Moore, Edie and Abram [19] observed therapeutic benefit in decompensated juvenile diabetics treated with an orally administered extract of pork duodenal mucosa. Duncan et al. [20] reported similar results with an orally administered extract of beef duodenal mucosa. In both studies, therapeutic effect persisted beyond acute interaction that may have occurred between gut and islet hormones. Deficiency, Dysfunction, and Dysgenesis Episodic hypoglycemia may onset at various intervals following gastric resection. During pregnancy, a single nutritional store serves both mother and growing fetus. Subclinical hepatic dysfunction and nutritional deficiency are not rare during gestation. Accelerated retinopathy may occur in diabetes, eclampsia, and hyperemesis gravidarum . Stillbirth, neonatal hypoglycemia, respiratory distress, and congenital malformation are more frequent in offspring of diabetic mothers. Hypothesis Though pernicious anemia and diabetes mellitus are functionally dissimilar and have different incidences, they superficially correspond 324 I Jerome D. Gorman · Diabetes Mellitus TABLE 1 Arbitrary Areas under Comparable Blood Sugar Curves when Fasting Blood Sugar Is 100 Percent Muscle Ratio Liver 1929 Crossover 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Mean. 747 996 838 724 264 284 656 766 762 650 756 612 912 1140 1046 940 332 324 844 810 876 931 854 824 .819 .874 .801 .770 .796 .875 .777 .946 .870 .698 .885 .743 .821 1930 Crossover 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 668 466 751 772 646 596 620 620 628 612 620 682 670 643 663 792 702 702 735 757 825 865 1050 744 860 724 836 630 702 732 782 808 751 761 810 786 748 814 .882 .565 .868 .735 .868 .693 .856 .742 .997 .872 .847 .872 .829 .856 .871 .978 .893 .938 .903 Mean. .845 with regard to heredity, age of onset, and involvement of vital polypeptides . Using pernicious anemia as heuristic model, one...

Purification of human intrinsic factor by affinity chromatography

Hydroxocobalamin was insolubilized by covalent coupling to albumin which in turn was coupled to bromoacetyl-activated cellulose. This product allowed specific adsorption of cobalamin-binding proteins from human gastric juice. The cobalamin-binding proteins were eluted by increase of temperature and addition of cyanocobalamin. After further chromatographic purification the net result of pure intrinsic factor was about 5% or some 75 mg from about 500 1 of gastric juice. The biological activity was proven by the Schilling test. It was homogeneous by sodium dodecyl sulphate gel electrophoresis and immunoelectrophoresis. Stokes radius (3.3 nm) was the same as the one of native intrinsic factor in gastric juice. The partial specific volume determined by ultracentrifugation in water and in deuterated solvent was 0.743 cm 3/g. The amino acid content was similar to the one of hog intrinsic factor. Sedimentation equilibrium ultracentrifugation indicated the presence of one or two protomers with a mol.wt of 30 000, unable to bind cyanocobalamin, and a monomer of mol.wt 60 000 binding one molecule of vitamin B 12.

The molecular size of human intrinsic factor in gastric juice.

Stokes radius for human intrinsic factor in complex with 57Co-cyano-cobalamin has been determined by Sephadex G-200 gel filtration. The experimental conditions were planned so as to simulate those occurring in the stomach: gel filtration was performed at 37° C and the mobile phase was gastric juice, pH 1.7 or pH 7. When amounts of intrinsic factor-bound vitamin B12 similar to the mean concentrations occurring in vivo are studied, the Stokes radius is 3.3 nm. From this value and data from the literature a molecular mass of 57,000 daltons can be calculated. It is concluded that human intrinsic factor occurs in the monomer form in gastric juice.

Observations on the effects of glucocorticoid administration in pernicious anemia.

The present study was an attempt to document further the changes that occur in patients with pernicious anemia during and after prednisolone. Therefore, 11 such patients were studied before, during 9–14 weeks of prednisolone administration, and up to 12 months afterwards. Schilling urinary excretion tests (UET) became normal in 5 patients, and 3 others had suboptimal improvement. Gastric juice intrinsic factor (IF) was demonstrated in 3 patients before prednisolone administration and 8 had increased amounts during therapy. Four patients had serum IF antibodies, and all titers declined. Parietal cells were present in gastric mucosal specimens from 9 of 11 individuals before, and from 7 of 9 individuals at the end of prednisolone administration. No clear relationship between an improvement of UET was demonstrable with the following: dosage or duration of prednisolone administration, degree of hypercorticism induced, presence of IF antibodies, or changes in gastric mucosa. The initial UET and/or gastric juice IF assay appeared higher in those who responded by improving their UET to normal, compared to those who had suboptimal or no UET improvement.

Inhibition of Free Intrinsic Factor Activity by Duodenal Juice

Evidence is presented which indicates that duodenal juice contains a component of high molecular weight which renders intrinsic factor incapable of binding vitamin B12. The extraordinary heat stability of this component suggests that it is not an enzyme. The degree of inhibition varies with different duodenal juices and is dependent upon the concentration of duodenal juice, the temperature, and the length of incubation. Total inhibition of posthistamine gastric juice intrinsic factor can be generally achieved by incubation with an equal volume of undiluted duodenal juice for 2 hr at body temperature. The inhibitory component acts on intrinsic factor rather than by competition with intrinsic factor for available vitamin B12.

Estimation of intrinsic factor and detection of intrinsic factor antibodies using non-radioactive cyanocobalamin and microbiological assay.

A method employing non-radioactive vitamin B(12) and microbiological assay is described for estimating intrinsic factor in gastric juice and for detecting antibody to intrinsic factor in serum. Satisfactory agreement was obtained between the results by this method and by a modification of the method of Ardeman and Chanarin (1963). During the first hour after gastric stimulation 11 patients with pernicious anaemia secreted between 0 and 240 units of intrinsic factor compared with between 1,600 and 39,000 units in 21 patients with other conditions. The results in three out of four patients with gastric atrophy were higher than those in pernicious anaemia but lower than in other conditions.

Blockade of vitamin B 12-binding sites in gastric juice serum and saliva by analogues and derivatives of vitamin B 12 and by antibody to intrinsic factor

A variety of vitamin B 12 analogues and derivatives (pseudo-vitamin B 12, anilide-B 12, aquoanilide-B 12, cobinamide, cobrynamide, 5,6-dimethylbenzimidazole and five different cobaloxime compounds) were tested for their ability to reduce the unsaturated vitamin B 12-binding capacity of (1) gastric juice, (2) serum and (3) saliva. The effect of these substances on specific binders in body fluids tested, was determined by rapid DEAE-cellulose chromatography. 1. 1. Gastric juice: All vitamin B 12-like substances, except 5,6-dimethylbenzimidazole and cobaloximes, bound well to non-intrinsic factor vitamin B 12 binders in normal gastric juice. Conversely, only intrinsic factor antibody and CN-B 12 blocked radioactive vitamin B 12 binding to intrinsic factor. The B 12 binders in pernicious anemia gastric juice were not effectively blocked by either intrinsic factor antibody or analogues. This precludes the use of analogues instead of intrinsic factor antibody for assay in vitro of intrinsic factor in gastric juice, in the system described. 2. 2. Serum: Unsaturated vitamin B 12-binding capacity of normal, chronic myelogenous leukemia and pernicious anemia serum was affected very similarly, and in a pattern resembling that of the non-intrinsic factor binder of normal gastric juice, except that cobaloxime C3, was effective in reducing the serum binding of vitamin B 12. Chromatography showed equal reduction of both α-globulin and β-globulin binders. 3. 3. Analogue interference with vitamin B 12 binders in saliva was essentially similar to, but more pronounced than, the results with serum and non-intrinsic factor binder in gastric juice.

Juvenile Pernicious Anemia

Histories have been presented of two pairs of sibling children with recurrent macrocytic anemia with megaloblastic bone marrow responding specifically to liver extract and vitamin B12. The clinical features and laboratory findings were similar to those of adult pernicious anemia in every respect except for the inconstant presence of histamine refractory achlorhydria. All the patients responded to vitamin B12 given parenterally, but in three to whom it was given by mouth no response was obtained. Two of these subsequently responded to oral B12 when it was accompanied by normal gastric juice. The other two developed histamine refractory achlorhydria while in hematologic remission. This is interpreted as proof that the anemia was due to deficient intrinsic factor in the gastric juice. Three patients showed evidence of disease of the spinal cord, in two of whom the symptoms were severe. These symptoms were compatible with a diagnosis of dorsolateral sclerosis, and improved with antipernicious anemia therapy. In one of these patients, treated with folic acid, the neurologic lesions were aggravated severely. Pernicious anemia due to the absence of gastric juice intrinsic factor occurs in children. The presence of free hydrochloric acid in the gastric contents does not preclude the possibility of the disease.

JUVENILE PERNICIOUS ANEMIA

Histories have been presented of two pairs of sibling children with recurrent macrocytic anemia with megaloblastic bone marrow responding specifically to liver extract and vitamin B12. The clinical features and laboratory findings were similar to those of adult pernicious anemia in every respect except for the inconstant presence of histamine refractory achlorhydria. All the patients responded to vitamin B12 given parenterally, but in three to whom it was given by mouth no response was obtained. Two of these subsequently responded to oral B12 when it was accompanied by normal gastric juice. The other two developed histamine refractory achlorhydria while in hematologic remission. This is interpreted as proof that the anemia was due to deficient intrinsic factor in the gastric juice. Three patients showed evidence of disease of the spinal cord, in two of whom the symptoms were severe. These symptoms were compatible with a diagnosis of dorsolateral sclerosis, and improved with antipernicious anemia therapy. In one of these patients, treated with folic acid, the neurologic lesions were aggravated severely. Pernicious anemia due to the absence of gastric juice intrinsic factor occurs in children. The presence of free hydrochloric acid in the gastric contents does not preclude the possibility of the disease.

Correlation of in vitro Activity of Normal Human Gastric Juice on Casein at pH 7.4 with Gastric Intrinsic Factor

The administration of mixtures of normal human gastric juice (intrinsic factor) and beef muscle (extrinsic factor) at pH 5 or 7 to patients with pernicious anemia results in increased blood production and clinical improvement,1,2In 1930, in association with Dr. C. W. Heath, unsuccessful attempts were made to show that gastric juice at pH 7.4 caused the production of amino acid from beef muscle. Griffiths3 showed that gastric juice incubated with beef muscle globulin at pH 6 produced certain chemical changes. Emerson and Helmer4 could not confirm his results. However, the present observations show that when casein was substituted for beef muscle, gastric juice at pH 7.4 did produce progressive changes in the casein.Normal human gastric juice was obtained free from bile after injection of histamine, filtered through gauze and placed in the ice box. A one percent solution of A. H. Thomas & Company washed casein was prepared at pH 7.4, avoiding excess of acid or alkali. To 50 ml. of this solution were added 5...