Acute Folate Deficiency Research Articles

Reticulocyte Folate Concentration: A Tool To Monitor Immediate Folate Availability

The utilization of folic acid during erythropoiesis is widely known and accepted in medical literature and deficiency is known to cause a characteristic megaloblastic anemia resulting from the inhibition or ineffective synthesis of DNA. Although the resultant megaloblastic anemia may take considerable time before evidence or symptoms present, there are more acute changes visualized on peripheral smear that are representative of a functional folate deficiency. In addition to erythrocyte macrocytosis, hypersegmentation of neutrophils can also be seen. Often times, despite these visualized changes measurement of serum folate and/or total red cell folate yields a result within the accepted “normal” range of the assay. It has been demonstrated that these visualized characteristics represent a functional folate deficiency and can be overcome with folic acid supplementation regardless of the measured folic acid levels indicating a yet to be understood mechanism of folate utilization. Here, we sought to measure the folic acid levels in the earliest erythrocyte progenitors in peripheral circulation, the reticulocytes. Methods Reticulocytes were isolated using anti-CD71 (the transferrin receptor) coated magnetic beads. After separation, a sample slide was made utilizing methylene blue for visual confirmation of reticulocyte isolation. The reticulocytes were then lysed with citric acid and a Nanodrop-1000 spectrophotometer was used to determine absorbance at 413 nanometers. This absorbance was used to determine the sample hemoglobin concentration from a simple calibration curve. The sample folic acid level was then determined using the lysing method utilizing mouse monoclonal anti-folate binding protein, paramagnetic particles coated in anti-mouse IgG, human serum albumin and milk folate binding protein. Results were calculated as nanogram of folate per gram of hemoglobin. Results Twenty-five samples from normal individuals, not taking folate supplements, were analyzed. The range of results was 2.51 to 17.38 with a mean level of 9.61. Conclusion This protocol effectively and efficiently allows for isolation of reticulocytes in numbers high enough for measurement of folate in nanogram per gram of hemoglobin. By this method we show the normal reticulocyte folate level to be approximately 3-15 ng/g of Hgb. This figure is consistent with the normal red cell folate concentration. Further analysis is planned for comparing these results in patients with a suspected functional folate deficiency but “normal” red cell folate levels. Efficient isolation of reticulocytes and measurement of folate levels will allow us to probe the underlying cause of acute folate deficiency seen in very sick patients. Disclosures: No relevant conflicts of interest to declare.

Further studies of acute folate deficiency developing during total parenteral nutrition.

Journal Article Further Studies of Acute Folate Deficiency Developing during Total Parenteral Nutrition Get access Nutrition Reviews, Volume 41, Issue 2, February 1983, Pages 51–53, https://doi.org/10.1111/j.1753-4887.1983.tb07457.x Published: 01 February 1983

5-Amino-4-Imidazolecarboxamide Riboside Potentiates Both Transport of Reduced Folates and Antifolates by the Human Reduced Folate Carrier and Their Subsequent Metabolism

Transport is required before reduced folates and anticancer antifolates [e.g., methotrexate (MTX)] exert their physiologic functions or cytotoxic effects. The folate/antifolate transporter with the widest tissue distribution and greatest activity is the reduced folate carrier (RFC). There is little evidence that RFC-mediated influx is posttranscriptionally regulated. We show that [(3)H]MTX influx in CCRF-CEM human childhood T-leukemia cells is potentiated up to 6-fold by exogenous 5-amino-4-imidazolecarboxamide riboside (AICAr) in a AICAr and MTX concentration-dependent manner. Metabolism to more biologically active polyglutamate forms is also potentiated for MTX and other antifolates. That potentiation of influx by AICAr is mediated by effects on the RFC is supported by analyses +/-AICAr showing (a) similarity and magnitude of kinetic constants for [(3)H]MTX influx; (b) similarity of inhibitory potency of known RFC substrates; (c) lack of potentiation in a CCRF-CEM subline that does not express the RFC; and (d) similarity of time and temperature dependence. Potentiation occurs rapidly and does not require new protein synthesis. Effects of specific inhibitors of folate metabolism and the time and sequence of AICAr incubation with cells suggest that both dihydrofolate reductase inhibition and metabolism of AICAr are essential for potentiation. Acute folate deficiency or incubation of CCRF-CEM with AICAr-related metabolites (e.g., adenosine) does not initiate potentiation. AICAr increases growth inhibitory potency of MTX and aminopterin against CCRF-CEM cells when both AICAr and antifolate are present for the first 24 hours of a 120-hour growth period. AICAr is the first small molecule that regulates RFC activity.

113. Acute folate deficiency following high volume continuous venovenous hemofiltration

113. Acute folate deficiency following high volume continuous venovenous hemofiltration

Maternal-fetal folate transfer: effect of ethanol and dietary folate deficiency

The effects of acute ethanol treatment and dietary folate deficiency on maternal-fetal folate transfer were studied to asses the hypothesis that the potentiation of ethanol's toxic effect on the fetus during ongoing folate deficiency was due to the impairment of folate transfer. Sprague-Dawley rats were fed either a folate-deficient diet (0.2 mg/kg) or a folate-sufficient diet (2 mg/kg) for an average of 11 weeks before pregnancy and continued until gestation day 11 when they were sacrificed. On gestation day 11, pregnant rats were treated with either ethanol (2.5 g/kg body weight) or isocaloric sucrose (control) followed by an intravenous administration of 3H-folate (2 muCi/100 g body weight) at 120 minutes. At 210 minutes, maternal blood and feto-placental tissues were removed for radioactivity measurement. Folate status and ethanol treatment had no effect on the distribution of 3H-folate in maternal circulation. However, contrary to the hypothesis, the uptake of 3H-folate by feto-placental tissues was increased in folate deficiency and by ethanol treatment, indicating that folate transfer was not impaired by the ethanol treatment. Other possibilities are discussed.

Folate deficiency in acutely ill patients

Ten cases of rapid onset pancytopenia due to acute folate deficiency, which occurred over a 2 year period are described. All patients were acutely ill and suffered serious haemorrhagic complications as a result of the thrombocytopenia. Where available, serum folate levels were depressed, whereas red cell folate and vitamin B12 levels were normal. Bone marrow aspirate was examined in 8 patients and all showed megaloblastosis.

Severe thrombocytopenia secondary to acute folate deficiency

A case of rapid onset pancytopenia, apparently due to acute folate deficiency, occuring in a severely ill post-operative patient is described, and the possible aetiological factors discussed.

Acute Folate Deficiency Associated with Intravenous Nutrition with Aminoacid‐Sorbitol‐Ethanol: Prophylaxis with Intravenous Folic Acid

Preoperative folate levels were initially normal in 30 patients with gastrointestinal tract disease but fell within 48 h by 60-95% in 20 patients who received intravenous nutrition for 6-12 d with aminoacid-sorbitol-ethanol (ASE). This depression persisted in patients not given folate supplements. Folate levels in 10 control patients not given ASE showed only minimal decline. Haematological changes were reduced to a minimum in 10 patients given 0.5 mg i.v. folic acid daily whilst eight unsupplemented patients showed evidence of megaloblastic haemopoiesis. Three of these eight patients developed thrombocytopenia and/or leukopenia which was fatal in one patient.

ACUTE FOLATE DEFICIENCY IN SURGICAL PATIENTS ON AMINOACID/ETHANOL INTRAVENOUS NUTRITION

Acute folate deficiency with pancytopenia and megaloblastic hæmopoiesis developed in four patients after abdominal operations; all four responded to folic acid over 3-9 days. Three of them had been given intravenous nutrition with aminoacid/ethanol before the blood changes developed. A prospective study of twenty-five surgical patients with gastrointestinal diseases revealed a high frequency of acutely developing negative folate balance. Megaloblastic hæmopoiesis and consequent blood changes were found in five patients. Treatment with intravenous nutrition correlated strongly with a fall in serum-folate and megaloblastic hæmopoiesis. Some surgical patients develop acute folate deficiency which may proceed to megaloblastic arrest of hæmopoiesis. Patients receiving intravenous nutrition containing ethanol are especially prone to this complication, which may be life-threatening if untreated. It is not yet known whether other forms of intravenous nutrition carry a similar risk.

Thymidylate concentration in megaloblastic anaemia.

MEGALOBLASTIC anaemia is thought to be caused by a disturbance of DNA synthesis in the bone marrow. The most common causes are deficiencies of folate or vitamin B12 which are thought to interfere directly or indirectly with supply of thymidine triphosphate (dTTP, thymidylate) one of the four immediate precursors of DNA1,2 (Fig. 1). We have previously shown that acute folate deficiency caused by the antifolate drug, methotrexate, does indeed cause a fall in the intracellular concentration of dTTP3. The present paper reports studies of the cellular concentration of dTTP and of the other three deoxyribonucleotide precursors of DNA, deoxyadenosine triphosphate (dATP), deoxyguanosine triphosphate (dGTP) and deoxycytidine triphosphate (dCTP) in the bone marrow cells and phytohaemagglutinin (PHA)-stimulated lymphocytes from patients with untreated megaloblastic anaemia due to vitamin B12 or folate deficiency. Surprisingly, no reduction in dTTP concentration was found in either cell.