Urinary Excretion Of Formiminoglutamic Acid Research Articles

Homocysteine and Folate in Pregnancy

The importance of folate during pregnancy was addressed 40 years ago by Bryan Hibbard (1) in his study of folate status in 1484 low-income obstetric patients from Liverpool. He assessed folate status as urinary excretion of formiminoglutamic acid. Abnormal formiminoglutamic acid excretion was related not only to placental abruption and spontaneous abortion but also to adverse outcomes in previous pregnancies, including prematurity, congenital defects, and perinatal mortality. Shortly thereafter, Hibbard and Smithells (2) suggested that folate deficiency in pregnancy may be related to central nervous system malformations, and Smithells started a series of observational and intervention studies demonstrating that adequate folate status reduced the risk of neural tube defects (NTDs), observations that eventually in the early 1990s were confirmed in large, randomized intervention trials (3)(4). It is now established that periconceptional folate supplementation reduces the occurrence and recurrence of NTDs (3)(4). The results obtained in many observational studies suggest that low folate intake or low circulating folate increases the risk of preterm delivery and low birth weight (5). However, a recent Dutch study on several B vitamins measured before and during pregnancy in healthy, well-nourished women demonstrated no association between the vitamin concentrations and birth weight or risk of early pregnancy loss (6). The results from randomized intervention trials with folic acid have been equivocal (5). Thus, the link between maternal folate status and birth weight is uncertain. The conclusions of the observational studies on vitamins and adverse pregnancy outcomes have been questioned because of methodologic weaknesses. These include inaccurate assessment of vitamin intake, measurement errors attributable to variable plasma-volume expansion during pregnancy, and confounders such as drug use and stress, intake of other micronutrients, …

Dietary nickel and folic acid interact to affect folate and methionine metabolism in the rat.

A previous experiment using rats indicated that dietary nickel (Ni), folic acid, and their interaction affected variables associated with one-carbon metabolism. That study used diets that produced only mild folate deficiency. Thus, an experiment was performed to determine the effect of a severe folate deficiency on nickel deprivation in rats. A 2 x 2 factorially arranged experiment used groups of six weanling Sprague-Dawley rats. Dietary variables were nickel, as NiCl2-6H2O, 0 or 1 microgram/g and folic acid, 0 or 4 mg/kg. All diets contained 10 g succinylsulfathiazole/kg to suppress microbial folate synthesis. The basal diet contained < 20 ng Ni/g. After 58 d, an interaction between nickel and folate affected the urinary excretion of formiminoglutamic acid (FIGLU) and the liver concentration of S-adenosylmethionine (SAM). Because of this, it is proposed that the physiological function of nickel is related to the common metabolism shared by SAM and FIGLU. Possibly the physiological function of nickel could be related to the tissue concentration of 5-methyltetrahydrofolate (MTHF) or tetrahydrofolate (THF).

Experimental maternal and neonatal folate status relationships in nonhuman primates

The influence of maternal dietary folic acid intake on folate status was studied in Cebus albifrons monkeys by feeding 10 or 250 micrograms/100 kcal dietary folic acid during pregnancy and 4 wk postpartum. Maternal, infant, and nonpregnant hematologic indices; blood and liver folate concentrations; and urinary formiminoglutamic acid excretion all varied with dietary folate intake and pregnancy status as did milk folate concentration in lactating dams. Maternal folate status, determined by plasma, red blood cell, and milk folate concentrations, as well as urinary formiminoglutamic acid excretion, all were correlated significantly with liver folate concentrations in neonates (r = 0.740, r = 0.919, r = 0.936, and r = -0.851, respectively). Results in these primates showed that neonatal folate status was related significantly to the dietary folate intake and folate status of the mother during pregnancy and lactation.

A Comparison of the Response of Woodchucks and Rats to Variations in Dietary Lipotrope and Protein Content

Juvenile woodchucks and weanling Fisher F344 rats were fed purified diets with or without supplemental lipotropic factors (choline, methionine, folic acid and vitamin B-12). The diets contained 10 or 20% protein. Lower weight gain due to low protein was observed in both species, while lipotrope depletion resulted in lower gain in male rats only. Urinary excretion of formimino-glutamic acid was higher due to low lipotrope in both species, as was relative liver weight. In rats, lipotrope depletion resulted in hepatic fatty metamorphosis at both levels of dietary protein with the low protein diet resulting in more severe lesions. No liver lesions were observed in woodchucks fed low lipotropes at the higher level of dietary protein, but fatty metamorphosis was observed in those fed the lower protein diets. The lesion was more severe in the low lipotrope group. The woodchuck appears to be less sensitive than the rat to induction of fatty liver by lipotrope deficiency, although the lesion was induced by lowering dietary protein.

Effect of Methionine on In Vivo Histidine Metabolism in Rats

Experiments were conducted to examine the effects of methionine supplementation on histidine metabolism in rats. All animals were fed 10% casein diets with a methionine content of either 0.6 or 1.1%. Experiments in which the animals were fed their diets containing an additional 1% histidine ad libitum for at least 10 days revealed that methionine-supplemented animals had a 49% reduction of plasma histidine and an 80% reduction in urinary excretion of formiminoglutamic acid (FIGLU) on day 10. This effect was not observed on day 5. In subsequent experiments rats were fed the control or test diet ad libitum prior to receiving their diets, containing a histidine load, by force-feeding. When a 100-mg histidine load was given on day 5, 24-hour urinary FIGLU excretion was 83% lower in methionine-supplemented animals. When rats were force-fed a 75-mg [ring-2-14C]histidine load on day 10, those receiving supplemental methionine oxidized 21% more of the histidine label to 14CO2 and excreted 61% less of the dose as urinary FIGLU in 24 hours. The activities of histidase and urocanase were unaffected by the methionine supplement. The results suggest that dietary methionine supplementation enhances the in vivo catabolism of histidine by stimulating one-carbon metabolism. Delivery of the methionine supplement by ad libitum feeding requires at least 5 days for this effect to be achieved.

Folate Deficiency in Rats Fed Amino Acid Diets

Growth rate, hematological changes, serum, erythrocyte and liver folate levels, and urinary excretion of formiminoglutamic acid (FIGLU) were measured in rats fed p-aminobenzoic acid (PABA)-free, sulfonamide-supplemented purified amino acid diets with and without folic acid and fiber, individually and in combination. Fiber had no effect on growth but was necessary to prevent mortality in the absence of folic acid. Folic acid did not affect growth during the first 40 days, but after this period rats failed to gain weight in the absence of folic acid. Although blood hematocrit was lower when the diet was devoid of fiber and folic acid and leucocyte counts were lower when the diets were devoid of folic acid, the hematological values remained within normal physiological limits for healthy rats of comparable age. FIGLU excretion was increased and serum, erythrocyte and liver folate levels were depressed when rats were fed folic acid-free diets for 28 days. Neutrophil hypersegmentation was clearly evident after 28 days of feeding the folic acid-free diets. The use of an amino acid diet without PABA but containing 5% fiber and 1% succinylsulfathiazole is a useful system to study chronic folic acid deficiency in the rat.

Increased urinary excretion of formiminoglutamic acid in nitrous-oxide-treated rats and its reduction by methionine.

Inhalation of nitrous oxide oxidises cob(I)alamin and inactivates methionine synthetase of which cobalamin is a co-enzyme. The biochemical changes in the rat following exposure to nitrous oxide resemble in some detail the changes present in patients with untreated pernicious anemia due to deficiency of cobalamin. There is a marked increase in the excretion of formiminoglutamic acid in the urine following exposure to nitrous oxide. A significant decrease is produced, while on N2O, by giving methionine. The explanation for these findings is discussed in the light of recent data on the effects of cobalamin inactivation.

Megaloblastic anemia and the requirement for folic acid in the cebus monkey (Cebus albifrons).

To study the development of folic acid deficiency, nine 3-year-old cebus monkeys (Cebus albifrons) were fed purified diets containing varying amounts of added folic acid. Monkeys fed the diet without added vitamin stopped growing and then lost weight. Macrocytic anemia and leukopenia developed, and megaloblastic changes were observed in precursors of both erythrocytes and leukocytes in the bone marrow. Urinary excretion of formiminoglutamic acid was increased significantly in these animals compared with controls. Repletion of deficient animals with injections of folic acid caused a rapid weight increase and reversed the hematological and biochemical abnormalities. It was estimated that the minimal folic acid requirement for adequate growth and normal hematological parameters was between 45 and 75 μg/kg body weight/day. To allow for needs above the minimal requirement, purified diets for cebus monkeys should be formulated to provide at least 150 μg of folic acid/kg body weight/day.

Blood and Liver Folacin Activity, Formiminoglutamic Acid Excretion, Growth and Hematology in Guinea Pigs Fed a Folacin Deficient Diet with and without Sulfonamides

Dietary folacin deficiency in the presence and absence of dietary sulfonamides was studied in the guinea pig for the purpose of relating the growth and hematologic effects of folacin deficiency to tissue and biochemical changes. Six-week old female guinea pigs fed control and folacin deficient diets with and without 0.1% sulfonamides for 6 to 7 weeks. Growth was significantly reduced in both groups fed the folacin deficient diets, and 25% of all deficient animals died. Macrocytic anemia was not present, but reduced leukocyte numbers were observed in folacin deficiency. Plasma and red blood cell folacin activities were reduced by about 50% in deficient guinea pigs in the presence and absence of dietary sulfonamides. Both liver total folacin activity and urinary formiminoglutamic acid excretion were not significantly altered by the degree of folacin deficiency obtained in this study.

A methionine-reversible folate deficiency in rats following the acute administration of diethylnitrosamine and α-napthylisothiocyanate

Acute doses of the hepatotoxic agents diethylnitrosamine (DEN) and α-naphthylisothiocyanate (ANIT) to young adult male rats led to the production of a folate deficiency as determined by an elevated urinary excretion of formiminoglutamic acid (FIGLU) 2 to 4 days following administration of the compounds. High dietary levels of methionine significantly reduced the elevated levels of FIGLU produced by the 2 chemicals. Dietary folate had no significant effect on the excretion of urinary FIGLU. Although the hepatic levels of S-adenosylmethionine (SAM) were significantly increased in rats fed the high dietary levels of methionine, an acute dose of DEN did not depress the hepatic levels of SAM. The results indicate that the methyl-reversible folate deficiency caused by hepatotoxic agents is not the direct consequence of altered hepatic levels of SAM.

Hypersegmentation in Iron Deficiency Anemia

<h3>To the Editor.—</h3> Hypersegmented neutrophils, a hallmark of vitamin B¹²and folic acid deficiency, have also been found, for unknown reasons, in chronic renal disease and as a hereditary disorder. The neutrophil hypersegmentation observed in iron deficiency,¹usually ascribed to an associated vitamin B₁₂or folate deficiency, may also occur without laboratory evidence of deficiency of these vitamins. The reason for this morphologic change in iron deficiency is not known, but abnormalities in folate metabolism have been suggested. Thus, the urinary excretion of formiminoglutamic acid (FIGLU) is often increased in iron deficiency, and experimentally induced iron deficiency may lead to a secondary folate deficiency.^2,3 In patients with normal serum folate levels, it is possible that a subclinical folate deficiency exists, since iron therapy may induce a fall in serum folate concentrations. It has also been suggested that the enzymeFIGLU transferase is iron-dependent and, therefore, not functioning

The effect of oral contraceptives on folate metabolism

We have studied the effect of oral contraceptives on folate metabolism, in order to test the hypothesis that folate deficiency of pregnant women may be partly due to impairment of folate metabolism. Serum folate, red cell folate, and urinary excretion of formiminoglutamic acid (FIGLU) were determined in 176 women receiving combination-type oral contraceptives (the Pill) and 140 normal control subjects. The group taking the Pill had significantly lower serum and red cell folate and higher urinary FIGLU excretion. There was a rise in serum and red cell folate and a fall of urinary FIGLU excretion within 3 months after stopping the Pill. The data demonstrate that women taking the Pill may have impaired folate metabolism and suggest that sex hormones may play a role in the development of folate deficiency in pregnancy.

Urinary formimino-glutamic acid excretion in nutritional anaemias of early childhood.

Urinary formimino-glutamic acid (FiGlu) excretion after histidine load was estimated by paper electrophoresis in 21 children with nutritional anaemia in the age group 6–36 months and compared with 10 normal subjects. The routine haematological investigations, serum iron and unsaturated iron binding capacity, and serum vitamin B12 were done and the response to therapy with the deficient haematinic was assessed. Urinary FiGlu excretion was raised in 4 children with megalopoiesis. The remaining 17 children had a normal or low FiGlu excretion.

Effects of sulfur-amino acids and choline on vitamin B 12 -deficient rats.

Rats were fed a diet based on unheated soybean flour without vitamin B&lt;sub&gt;12&lt;/sub&gt; added. This diet leads to a depletion of vitamin B&lt;sub&gt;12&lt;/sub&gt; as evinced from a decrease in liver concentration of the vitamin and an increased urinary excretion of methylmalonic acid following a load of propionate. Urinary excretion of formiminoglutamic acid after a histidine load was likewise increased. Supplementation of this diet with either methionine or cysteine improved weight gain, increased liver level of vitamin B&lt;sub&gt;12&lt;/sub&gt; and decreased excretion of methylmalonic and formiminoglutamic acids. Choline raised liver vitamin B&lt;sub&gt;12&lt;/sub&gt; and decreased excretion of methylmalonic acid. Addition of both choline and methionine to the diet increased liver vitamin B&lt;sub&gt;12&lt;/sub&gt; more than choline or methionine alone and decreased excretion of formiminoglutamic acid more than choline alone.

Factors affecting formiminoglutamic acid excretion in vitamin B 12 deficiency.

1. Formiminoglutamic acid, a product of the catabolism of histidine, is excreted in abnormally large amounts in the urines of vitamin B(12)-deficient rats and of vitamin B(12)-deficient sheep; the excretion is reduced to negligible amounts after administration of vitamin B(12). 2. After administration of certain methyl donors to vitamin B(12)-deficient rats or sheep urinary excretion of formiminoglutamic acid is temporarily decreased. 3. Irrespective of the pteroylglutamic acid status of the animals neither vitamin B(12)-deficient rats nor vitamin B(12)-deficient sheep have the ability to deal efficiently with histidine. 4. In sheep, urinary excretion of formiminoglutamic acid is increased after administration of aminopterin; treatment with pteroylglutamic acid restores the ability of the animal to deal with the catabolic products of histidine. 5. The possible functions of vitamin B(12) and methionine in relieving a virtual deficiency of pteroylglutamic acid are discussed.

Urinary excretion of formiminoglutamic acid in children with riboflavin deficiency.

Urinary excretion of formiminoglutamic acid following an oral dose of histidine was decreased in children with riboflavin deficiency than in those without it.

Tetrahydrofolate-dependent enzyme activities of the rat liver in riboflavin deficiency.

Urinary excretion of formiminoglutamic acid (FIGLU) following an oral, intraperitoneal, intramuscular, or intravenous load with L-histidine-monohydro-chloride was markedly reduced in rats when fed on a riboflavin deficient diet for 11-30 days. The assay of tetrahydrofolate-dependent enzyme activity of the liver revealed that there were a marked deeraase in the activity of N5, 10 methylenetetrahydro-folate ieductase and a considerable decrease in that of N5 methyltetrahydro-folate transferase of the liver from the riboflavin deficient rats. Results of bioassay using L. casei, St. faecalis and Pediococcus cerevisiae of folate compounds of the liver revealed a tendency toward relative increase in folato deriva-tives other than N5 methyltetrahydrofolate in the liver of riboflavin deficient rats. From these results it was assumed that a decreased activity in both the N5, 10 methylenetetrahydrofolate reductase and N5 methyltetrahydrofclate trans-ferase was induced by riboflavin deficiency, and then that the decrease in the activity of the both enzymes caused an accumulation of tetrahydrofolate com-pounds other than N5 methyltetrahydrofolate, thus affording a relatively large amount of free tetrahydrofolate available for the formiminotransferase reaction, with a consequence of rapid conversion of FIGLU into glutamic acid. Free methionine levels of the liver was not found to be increased but slightly decreased in riboflavin deficient rats as compared with those of control rats.

Secondary Folate Deficiency Induced in the Rat by Dietary Iron Deficiency

The effects of iron deficiency on folate metabolism in rats were studied. Dietary iron deficiency was induced in 18-day-old male rats, following which the animals developed the expected hypochromic, microcytic anemia. In addition, notwithstanding that the diet contained adequate folate, iron deficiency resulted in biochemical and morphological changes of folate deficiency such as increased urinary excretion of formiminoglutamic acid, decreased serum folate and megaloblastoid dysplasia of the bone marrow elements. In a second experiment, iron deficiency was shown to result in a decreased activity of the enzyme glutamate formimino-transferase isolated from livers. It was concluded that a secondary folate deficiency can be induced by a dietary deficiency of iron and that this defect in folate metabolism is related to the decreased activity of the enzyme formimino-transferase whose optimal activity is dependent on iron.

Megaloblastic and transitional megaloblastic anemia associated with chronic liver disease: A study of nine cases

P ATIENTS with liver disease are often anemic [7-51. In some, particularly after acute blood loss, the anemia is normochromic and normocytic in type [6] ; in others, complicated by iron deficiency, hypochromic microcytic anemia may develop [7]. In most cases, however, the anemia is macrocytic [2,8-701. Early workers considered that this macrocytosis was identical with Addisonian pernicious anemia [ 7 7,721 and the result of failure of storage or activation of “hemopoietic principle” in the damaged liver [ 73,741. Subsequently, differences between the macrocytic anemia usually seen in liver disease and pernicious anemia were demonstrated: the bone marrow is generally normoblastic or macronormoblastic in liver disease and invariably megaloblastic in untreated pernicious anemia ; free gastric hydrochloric acid can usually be demonstrated in cirrhosis [Z], whereas achlorhydria is the rule in pernicious anemia [ 741; in cirrhosis the serum level of vitamin Brz is normal or high and the absorption of radioactive vitamin Brz is normal [78], whereas in pernicious anemia the serum level of vitamin Bi2 is reduced and the absorption of labeled vitamin Biz is impaired ; and finally, there is usually little or no hemopoietic response to the administration of vitamin Brz in patients with cirrhosis, in contrast to its efficacy in pernicious anemia [ 74. Megaloblastic hemopoiesis has not been reported often in patients with chronic liver disease. This association is recorded in only thirtysix instances in the literature [72,79-261. Some of these cases undoubtedly represented the coincidental association of classic Addisonian pernicious anemia in patients with chronic liver disease; others, the development of a nutritio.nal deficiency of folic acid or vitamin Brz. However in many instances the pathogenesis of the anemia was obscure and a variety of metabolic faults due to the liver disease were postulated. Gastric acidity and vitamin Brz absorption were tested in some [23] and the serum level of vitamin Brg was estimated in others [24]. The folic acid status in some cases has been assessed by estimations of the urinary levels of “folic acid” [22] ; by the urinary excretion of formiminoglutamic acid (FIGLU) following histidine challenge [25,26], or by the microbiological assay of serum folic acid activity [24]. But as yet, no extensive analysis has been reported of the various factors contributing to megaloblastic hemopoiesis in patients with chronic liver disease. It is the purpose of this paper to record the results of folic acid and vitamin Biz studies in nine patients with chronic liver disease and megaloblastic or transitional megaloblastic hemopoiesis, and to discuss the pathogenesis of the anemia.

The effect of large intravenous dosesof methotrexate on urinary formiminoglutamic acid excretion

A comparison was made of the effect of small, daily oral doses and large, intermittent intravenous doses of methotrexate (amethopterin) on folic acid metabolism in patients with acute leukemia. The urinary excretion of formiminoglutamic acid was used as a measure of effectiveness in the two treatment regimens. Administration of methotrexate intravenously in a dose of 3 mg. per kilogram body weight was found to produce a brief but profound inhibition of folic acid metabolism as measured by the excretion of formiminoglutamic acid in the urine of patients with acute leukemia.