Development of mechanisms for intestinal absorption of vitamin B12 in growing rats

1963 ◽  
Vol 204 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Agna Boass ◽  
T. Hastings Wilson
Keyword(s):  
Intrinsic Factor ◽  
Vitamin B ◽  
Newborn Rats ◽  
Drastic Reduction ◽  
Intestinal Uptake ◽  
Growing Rats ◽  
Stages Of Growth ◽  
Vitamin Uptake ◽  
Newborn Animals ◽  
Stimulation Of

Intestinal uptake of vitamin B12, with and without gastric intrinsic factor (IF), was studied with isolated tissue from rats at various stages of growth. The intestine from fetal and newborn animals showed extremely high uptake of the vitamin in the absence of IF. This IF-independent B12 uptake fell rapidly with time, approaching adult levels at about 14 days. Stimulation of B12 uptake by IF was detectable in the intestine of newborn rats in spite of the high vitamin uptake in its absence. The per cent stimulation due to added IF increased during the 1st 2 weeks because of drastic reduction of the IF-independent B12 uptake. The development of IF and pepsinogen in the stomach of growing rats was also investigated. The stomach wall of fetal and newborn rats contained less than 1% of the IF found in the adult. After the 1st week the amount increased rapidly, reaching adult levels at weaning. A rapid increase in pepsinogen content did not occur until the 3rd week. As the IF-independent transport system decreased in activity, intrinsic factor appeared in the stomach and the adult mechanism became the predominant system for B12 absorption.

Some species differences in the intrinsic factor stimulation of B12 uptake by small intestine in vitro

1959 ◽  
Vol 197 (4) ◽  
pp. 926-928 ◽  
Author(s):  
T. Hastings Wilson ◽  
Elliott W. Strauss
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Species Differences ◽  
Intrinsic Factor ◽  
Vitamin B ◽  
Guinea Pig Ileum ◽  
Rat Intestine ◽  
Intrinsic Factors ◽  
Stimulation Of

Sacs of everted small intestine from a variety of animals were incubated in bicarbonate-saline containing vitamin B12 with and without intrinsic factor (IF). B12 uptake by rat intestine was stimulated only by its own intrinsic factor. Guinea pig ileum responded to all intrinsic factors tested (guinea pig, rat, hog, hamster, human being and rabbit). The intestines of hamster and rabbit were intermediate in specificity, responding to some, but not all, of the IF preparations. Species differences occur in both the intestine and intrinsic factor preparations. The guinea pig ileum was suggested as a possible assay for both hog and human IF.

Factors controlling B12 uptake by intestinal sacs in vitro

1960 ◽  
Vol 198 (1) ◽  
pp. 103-107 ◽  
Author(s):  
Elliott W. Strauss ◽  
T. Hastings Wilson
Keyword(s):  
Small Intestine ◽  
Low Temperature ◽  
Guinea Pig ◽  
Calcium Ion ◽  
Intrinsic Factor ◽  
Intestinal Wall ◽  
Vitamin B ◽  
Anaerobic Conditions ◽  
Intestinal Uptake

Sacs of everted small intestine were incubated in bicarbonate-saline containing radioactive vitamin B12 with or without a source of gastric intrinsic factor (IF). In both the hamster and guinea pig the lowest ileum was most active in B12 uptake in the presence of intrinsic factor, the upper jejunum showing little or no uptake. Low temperature and anaerobic conditions completely abolished the stimulatory effect of IF on B12 uptake. Intrinsic factor did not bind to the intestinal wall in the absence of B12 (even in the presence of calcium ion) as the IF activity could be completely removed by gentle washing of the tissue. The vitamin and intrinsic factor must be present together to cause intestinal uptake of B12.

An assay for gastric intrinsic factor

1963 ◽  
Vol 204 (1) ◽  
pp. 97-100 ◽  
Author(s):  
Agna Boass ◽  
T. Hastings Wilson
Keyword(s):  
Gastric Mucosa ◽  
Positive Reaction ◽  
Intrinsic Factor ◽  
Quantitative Assay ◽  
Vitamin B ◽  
Stimulation Of

The stimulation of vitamin B12 uptake by small segments of hamster ileum in the presence of gastric intrinsic factor (IF) has been utilized as a quantitative assay for rat and hamster IF. About 100–150 small segments of everted ileum of the hamster were mixed in a beaker and aliquots of approximately 10 were incubated in flasks containing radioactive B12 with or without IF. Within a certain range of IF concentrations, B12 uptake into the tissue was proportional to the IF added. Of all the tissues studied only gastric mucosa showed IF activity under these conditions. This assay was not only specific for gastric IF, but was also extremely sensitive, giving a positive reaction with a concentration of 0.1 mg gastric mucosa per milliliter of incubating solution.

scholarly journals Glucose stimulation of insulin secretion from the isolated pancreas of foetal and newborn rats

Diabetologia ◽  
1969 ◽  
Vol 5 (4) ◽  
pp. 260-262 ◽  
Author(s):  
K. Asplound ◽  
S. Westman ◽  
C. Hellerste�m
Keyword(s):  
Insulin Secretion ◽  
Newborn Rats ◽  
Glucose Stimulation ◽  
Isolated Pancreas ◽  
Stimulation Of

Progressive Imbalance and Visual Impairment in a Patient With Diabetes

2021 ◽  
pp. 248-250
Author(s):  
Neeraj Kumar
Keyword(s):  
Lower Limb ◽  
Peripheral Blood ◽  
Blood Smear ◽  
Serum Gastrin ◽  
Methylmalonic Acid ◽  
Intrinsic Factor ◽  
Peripheral Blood Smear ◽  
Vitamin B ◽  
Neurologic Manifestations ◽  
History Of

A 72-year-old man with hypothyroidism and type 2 diabetes sought care for a 3-year history of slowly progressive, ascending lower limb paresthesias and imbalance. Three months earlier, he noted subacute onset of finger numbness and substantial worsening of imbalance with infrequent falls. He also had a 1-year history of progressive visual decline that persisted despite cataract surgery. Additional symptoms included intermittent light-headedness and confusion. Laboratory evaluations showed a decreased hemoglobin value and an increased mean corpuscular volume. Macrocytic red blood cells were noted on a peripheral blood smear. Serum vitamin B12 level was less than 70 ng/L. Levels of plasma homocysteine and serum methylmalonic acid were markedly increased to 375 µmol/L and 143 nmol/L, respectively. Serum copper level was normal. Serum parietal cell antibodies were increased to 46 U, and intrinsic factor antibodies were absent. Serum gastrin was markedly increased. The clinical presentation in this patient suggested a myeloneuropathy. His vitamin B12 level was undetectable and accompanied by a macrocytic anemia and increased methylmalonic acid and homocysteine levels. Even though intrinsic factor antibodies were negative, the clinical picture was supportive of subacute combined degeneration in the setting of pernicious anemia. The patient was started on vitamin B12 replacement. At 6-month follow-up he had striking improvement in gait and vision. The light-headedness and confusion were no longer present. His examination was remarkable only for mild impairment, with tandem gait and a slightly positive Romberg sign. The lower limb reflexes were reduced. Impaired position perception at the toes persisted, but vibration perception in the lower limbs improved. Laboratory investigations showed normalization of the hemoglobin, vitamin B12, methylmalonic acid, and homocysteine levels. The serum gastrin level had improved but was still increased at 742 pg/mL. The best-characterized neurologic manifestations of vitamin B12 deficiency include myelopathy and myeloneuropathy. Autonomic neuropathy, optic neuropathy, and neuropsychiatric manifestations have also been reported. Neurologic manifestations may occur without evidence of the characteristic hematologic derangement, megaloblastic anemia. Macrocytosis or hypersegmented neutrophils on peripheral blood smear may be clues.

Cobalamin transport proteins and their cell-surface receptors

2003 ◽  
Vol 5 (18) ◽  
pp. 1-18 ◽  
Author(s):  
Bellur Seetharam ◽  
Raghunatha R. Yammani
Keyword(s):  
Cell Surface ◽  
Blood Cells ◽  
Plasma Membranes ◽  
Intrinsic Factor ◽  
Transport Proteins ◽  
Cell Surface Receptors ◽  
Vitamin B ◽  
Cellular Transport ◽  
Surface Receptors ◽  
Molecular Aspects

The primary function of cobalamin (Cbl; vitamin B12) is the formation of red blood cells and the maintenance of a healthy nervous system. Before cells can utilise dietary Cbl, the vitamin must undergo cellular transport using two distinct receptor-mediated events. First, dietary Cbl bound to gastric intrinsic factor (IF) is taken up from the apical pole of ileal epithelial cells via a 460 kDa receptor, cubilin, and is transported across the cell bound to another Cbl-binding protein, transcobalamin II (TC II). Second, plasma TC II–Cbl is taken up by cells that need Cbl via the TC II receptor (TC II-R), a 62 kDa protein that is expressed as a functional dimer in cellular plasma membranes. Human Cbl deficiency can develop as a result of acquired or inherited dysfunction in either of these two transmembrane transport events. This review focuses on the biochemical, cellular and molecular aspects of IF and TC II and their cell-surface receptors.

scholarly journals GAMMA GLOBULIN PRODUCTION IN GERMFREE RATS AFTER BACTERIAL CONTAMINATION

1959 ◽  
Vol 110 (5) ◽  
pp. 675-684 ◽  
Author(s):  
Bengt E. Gustafsson ◽  
Carl-Bertil Laurell
Keyword(s):  
Bacterial Contamination ◽  
Gamma Globulin ◽  
Microbial Flora ◽  
Lag Phase ◽  
Bacterial Cells ◽  
Newborn Rats ◽  
Growing Rats ◽  
Different Types ◽  
Germfree Rats ◽  
Normal Microbial Flora

The earlier observed pronounced hypogammaglobulinemia in germfree rats of different ages has been confirmed. Using an immunologic technique the concentration of immunologic gamma globulins were found to vary between 10 and 15 per cent of the values observed in ordinary rats. Upon contamination of germfree rats with the normal microbial flora a pronounced lag phase was noted before the gamma globulin level became normal. This lag phase was most pronounced in growing rats. Newborn rats seem to start gamma globulin production more rapidly than older germfree rats. The response with regard to gamma globulin production on contamination of germfree rats with different types of bacterial cells through the natural routes is not identical.

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