Nature of the Intrinsic Factor of Castle

Hall, Byron E.

doi:10.1136/bmj.2.4679.585

Cited by 47 publications

(3 citation statements)

References 6 publications

(6 reference statements)

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“…Whereas some may show an almost optimal response to daily doses of 15 micrograms (18) and some can be successfully treated with daily oral doses of 50 micrograms (19), failures have been reported with daily doses of as much as 250 micrograms (20)(21)(22). This variation is well illustrated in Figure 3 at the 50-microgram dose.…”

Section: Resultsmentioning

confidence: 99%

A Dual Mechanism of Vitamin B12 Plasma Absorption1

Doscherholmen¹,

Hagen²

1957

J. Clin. Invest.

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Recent reports have described two types of plasma absorption curves following the oral administration of vitamin B1.,. With microbiologic assay methods, after massive doses of vitamin. Bs, early significant plasma levels have been found indiscriminately in both pernicious anemia patients and control subjects (1, 2). On the other hand, two independent laboratories, using radio-labeled cyanocobalamin, have successfully determined plasma absorption curves after the oral administration of only 0.46 to 1.0 microgram doses (3, 4).With these small amounts of vitamin B12 a distinctly different type of absorption curve was found in normal subjects and in pernicious anemia patients when intrinsic factor was added. This curve was characterized by little or no plasma radioactivity during the first four hours of the test and a peak concentration in the 8-to 12-hour interval. Furthermore, there was clear differentiation between control subjects and patients with pernicious anemia, because at these dosage levels the latter without added intrinsic factor showed insignificant plasma radioactivity.In this investigation plasma absorption curves were obtained in pernicious anemia patients with and without intrinsic factor, as well as in control subjects after the oral administration of test doses of radio-labeled cyanocobalamin which ranged from 0.56 to 500 micrograms. This included a dosage range not previously examined. MATERIAL AND METHODSCobalt'-labeled vitamin B. 2 used in test doses had an initial specific activity of 1,137 microcuries per mg., while that of the Cotm-labeled vitamin Bn-2 used was 893 microcuries per mg. Crystalline non-radioactive vitamin B,2 was added as necessary to make up the desired test

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Section: Resultsmentioning

confidence: 99%

A Dual Mechanism of Vitamin B12 Plasma Absorption1

Doscherholmen¹,

Hagen²

1957

J. Clin. Invest.

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“…(2) Vitamin B12 may be destroyed by digestive secretions unless protected by intrinsic factor (Hall, 1950) and, if so, the small amount of secretions in the fasting state may not destroy all of the 50 pg. dose.…”

Section: Discussionmentioning

confidence: 99%

“…The majority of the reports have come from America, and include those by Berk et al (1948), Spies et al (1949), Hall (1950), Meyer et al (1950), Conley et al (1951Conley et al ( , 1952, Glass et al (1952Glass et al ( , 1953, and' Unglaub et al (1954). British publications are those of Ungley (1950Ungley ( , 1951, and Girdwood (1953).…”

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confidence: 99%