Hepatic Folate in Man

Abstract

Ionizing Radiation-Hems 2,249 persons were all exposed to 5 rads, and in practice their exposure was on average much lower, the exposed group would still be less than 20% of the minimum size (in man-years) to permit detection of radiation-induced leukaemia and an even smaller fraction of the size (in man-generations) required for detection of a mutation attributable to the increased radiation. Summary and ConclusionsIn order to detect radiation effects by a population study it is, of course, essential that the population be large enough for the radiation effects to be statistically significant. For exposure of man to low doses of radiation at low dose rates the minimum population size to permit detection of radiation-induced leukaemia is many tens of thousands of man-years; for detection of dominant mutations attributable to the increased radiation the necessary population (in man-generations), as estimated from mouse data, is even larger. Exposed populations which have been surveyed so far are smaller than the minimum theoretical size and would need to be studied for an impracticably long time before either a mutation attributable to the increased radiation at a single locus or radiation-induced leukaemia could be detected. Stevenson (1957), in his examination of this problem, also concluded that it appeared unlikely that populations could be found of sufficient size to permit detection of mutations induced by background radiation.In conclusion it should be emphasized that, in addition to the difficulty of fulfilling the requirement for a minimum population size, if a population study were undertaken to detect radiation effects additional practical problems are fikely to be encountered in setting up a satisfactory control population (Griinberg, 1964) Medicine (Herbert, 1964;Chanarin, 1964). Abnormal results with both these tests are frequent in hospital patients who are haematologically normal, and it is uncertain whether these abnormal values indicate subclinical folate deficiency or merely the unsatisfactory nature of the tests. The purpose of this study was to correlate the results of these tests of folic-acid function with direct assay of the amount of folic acid in the tissues. The liver is the most satisfactory tissue for this purpose, since it contains most of the folates in the body and is the site of the important synthetic reactions involving the folate coenzymes. Donaldson and Keresztesy (1959) have found that hepatic folate in the horse is 5-methyltetrahydropteroyl-monoglutamate. This paper also reports observations on the nature of the folate compounds in human liver. Materials and MethodsObservations were made on 26 patients admitted to the surgical wards with a variety of disorders (see Table), and who were all undergoing a laparotomy. The day before operation a blood sample was obtained for a full blood count, including enumeration of five-lobed neutrophils, and for the microbiological assay of the levels of serum folate and vitamin B12' Fifteen grammes of 1-histidine-mono-HCl was given orall...

Hepatic and serum folates in patients fasting and after oral folic acid

“…The range of liver folates in the patients investigated here is similar to that obtained by Chanarin et al (1966). Although there appears to be some relationship to the fasting serum folate in the majority of the patients, the finding of a high liver folate in the presence of a low serum folate in a few renders the results statistically not significant, a conclusion also applicable to the findings in the surgical patients of Chanarin et al (1966).…”

“…Although there appears to be some relationship to the fasting serum folate in the majority of the patients, the finding of a high liver folate in the presence of a low serum folate in a few renders the results statistically not significant, a conclusion also applicable to the findings in the surgical patients of Chanarin et al (1966). Analysis of their results yields an insignificant value for r of 0 04.…”

“…Waters (1963) recorded excellent correlation between the serum and liver folates in megaloblastic anaemias and in a few control patients. Chanarin, Hutchinson, McLean, and Moule (1966) apparently confirmed this relationship in a series of hospital patients, but their results are actually not significant. We have therefore compared the serum and hepatic folates in a similar group of patients.…”

Investigation of folic acid requirements in pregnancy.

“…Unfortunately the serum folate level is a less precise measurement of body stores than, for instance, the hepatic folate (Chanarin et al, 1966), though superior to the F.I.G.L.U. test in pregnancy (Chanarin et al, 1963;Chisholm and Sharp, 1964) and probably a more sensitive index than the presence of overt megaloblastic anaemia (Herbert, 1964).…”

Serum and Urinary Folate in Liver Disease

“…In the adult folate is mainly stored in the liver in quantities of about 5-20 mg. (Chanarin et al, 1966). Hepatic dysfunction affects vitamin storage (Baker et al, 1964), and vitamin B12, for instance, is liberated into the blood stream during liver disease (Stevenson and Beard, 1959).…”