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At least 649 records · Page 36Linked to original sources
PubMed1998

Intestinal absorption and enterohepatic circulation of folic acid: effect of ethanol.

This study sought to determine the intestinal in vivo absorption of folic acid by the whole intestine, and the appearance of this compound in bile in control and ethanol-fed rats. Intestinal folic acid absorption in rats with the bile duct cannulated decreased in ethanol-fed rats with respect to control rats. This difference was significant at 1 and 2.5 microM concentrations of folic acid. This result is in contrast with previous work in our laboratory on rats with intact bile ducts, where ethanol-fed rats had an increase in folic acid absorption. The results obtained in the present work suggest an impaired enterohepatic recycling of folic acid in ethanol-fed rats.

Animal Feed↗
PubMed1964

MICROBIOLOGICAL ASSAY OF FOLIC ACID ACTIVITY IN HUMAN SERUM.

A method is described for the microbiological assay of folic acid activity in serum with Lactobacillus casei as test organism and a modified medium in which the organism gives a greater growth response than in media previously detailed. The results of experiments carried out to validate the use of this medium are shown. In 94 control subjects levels of folic acid activity in the serum ranged from 2. to 28 mmug./ml. (mean 7.8). The values in nine out of 10 patients with megaloblastic anaemia due to deficiency of folic acid were 1.0 mmug./ml. or less and one result was 2.0 mmug./ml. In six patients with megaloblastic anaemia associated with pregnancy the results ranged from 0.7 to 4.0 mmug./ml., and in untreated pernicious anaemia 28 out of 31 results were within or above the control range and three values were just below the lower limit of normal.

Anemia↗
PubMed2004

Homocysteine and folic acid are inversely related in black women with preeclampsia.

Black women have an increased risk of preeclampsia compared with white women. Plasma homocysteine is increased in preeclampsia. Homocysteine concentrations are affected by nutritional deficiencies, particularly decreased folic acid and B12, leading to increased homocysteine. Previous studies have reported racial differences in nutritional intake including folic acid. Therefore, we investigated whether there were racial differences in plasma homocysteine, folic acid, and vitamin B12 among women with preeclampsia. We tested for an association between homocysteine and folic acid and B12, and we hypothesized an inverse relationship of homocysteine and folic acid in preeclampsia, more so in black women in whom preeclampsia developed. Black women with preeclampsia (n=26) had elevated homocysteine concentrations (8.7+/-1.4 micromol/L) compared with black women with normal pregnancy (n=52, 7.6+/-0.5 micromol/L), white women with preeclampsia (n=34, 7.5+/-0.6 micromol/L), and white women with normal pregnancy (n=48, 5.5+/-0.3 micromol/L). Folic acid concentrations were lower in black women (14.1+/-0.8 ng/mL) compared with white women (18.5+/-0.9 ng/mL, P<0.01). However, plasma homocysteine was inversely related to folic acid only among black women with preeclampsia (r=-0.23, P=0.01). These racial differences may have implications for the higher rates of preeclampsia in this group and may have long-term implications for future cardiovascular risk. Racial differences in diet, adherence to folic acid supplementation, or interactions of nutritional and maternal factors warrant further study by race and pregnancy status.

Adolescent↗
PubMed2003

Measurements of sub-nanomolar concentrations of unmetabolised folic acid in serum.

We describe a combined HPLC/microbiological assay procedure for the sub-nanomolar analysis of unmetabolised folic acid (pteroylglutamate) in human serum. This metabolically unaltered form of the vitamin arises following the consumption of folic acid either in supplemental form or in fortified foods. Following HPLC separation of folic acid from other folate derivatives the folic acid fraction was concentrated by C(18) Sep-Pak cartridges and assayed by Lactobacillus casei microbiological assay. The present assay allows the quantitation and kinetic analysis of the effects of consumption of folic acid.

Chromatography, High Pressure Liquid↗
PubMed1993

Folic acid and vitamin B12 status of vervet monkeys used for nutritional research.

Plasma and red blood cell (RBC) folic acid levels, as well as plasma vitamin B12 levels were determined in Vervet monkeys (Cercopithecus aethiops). All the vervets were apparently healthy and without symptoms or lesions typical of folic acid and/or vitamin B12 deficiencies. Competitive protein binding radioassays were used to determine folate and vitamin B12 values in animals fed 4 different diets. The B12 levels for all the groups ranged between 866 and 5867 pg/ml and showed an inverse relationship with the FA measurements. The lowest mean RBC folic acid content in a group fed an atherogenic diet for 3 years was 12.8 ng/ml. For the other 3 diets, mean RBC folic acid levels were 90.7, 132.3 and 152.8 ng/ml, respectively. A megadose of 25.6 mg of folic acid per day for 99 days was given to 3 adult males. No obvious toxic effects were observed in these animals although mean RBC folic acid levels increased to 1013 ng/ml.

Animal Nutritional Physiological Phenomena↗
PubMed1995

The folic acid requirements of starting broiler chicks fed diets based on practical ingredients. 1. Interrelationships with dietary choline.

Five experiments were conducted to evaluate the effect of dietary supplemental folic acid in starting broiler chick diets. In the first two experiments, basal diets based on corn and soybean meal contained 10 micrograms/kg vitamin B12 but no supplemental methionine or choline. Chicks showed curvilinear responses to folic acid supplementation with maximum growth and feed efficiencies from 1.45 mg/kg diet. The liver folic acid response was also curvilinear but reached a plateau at 1.70 mg folic acid/kg diet. The basal diet for three additional experiments contained soybean meal that had been washed with methanol to remove most of the choline. The basal diet contained only 750 mg/kg choline. Chicks exhibited a larger growth response to folic acid at low choline levels as evidenced by a significant folic acid by choline interaction. Choline and folic acid both increased tibia length and width. Folic acid supplementation increased but then decreased valgus deformity. Choline chloride supplementation also decreased the incidences of valgus and varus deformities and decreased bone ash, but increased the incidence of tibial dyschondroplasia. It is concluded that chicks fed practical ingredient-based diets require 1.3 mg folic acid/kg diet with low levels of choline, but only 1.2 mg folic acid/kg when choline is offered near the NRC recommended level of 1,300 mg/kg of choline.

Animals↗
PubMed1998

[Effects of iron supplement on metabolism of iron and folic acid in rat liver].

OBJECTIVE: To study the effects of iron supplement on metabolism of iron and folic acid. METHODS: Thirty-two weanling Sprague-Dawley rats were divided into two groups, iron-normal and iron-deficiency, feeding twice a day with synthetic fodder containing 800 micrograms and less than 20 micrograms iron per day, respectively. Half of the rats in each group were supplemented with 8,000 micrograms of iron daily, and the other half of the rats were fed unchanged. Finally, four groups of rats, i.e., iron-normal with iron supplement, iron-deficiency with iron supplement, iron-normal and iron-deficiency, were set up. The fodder for all the four groups contained less than 10 micrograms of folic acid per day. RESULTS: Iron deficiency affected the growth, body weight and hemoglobin level of the rats, and their liver weight and iron content in the liver were significantly lower than the normal level, and their folic acid level was significantly higher than that in iron-normal rats. The growth, weight and hemoglobin level improved significantly, and iron content in the liver increased rapidly and exceeded the normal level after supplement with iron, while folic acid level in the liver declined until that was significantly lower than the normal. CONCLUSION: Folic acid content in the rats with deficiency both in iron and folic acid declined further after iron supplement, and no significant change was found in iron-normal rats.

Animals↗
PubMed1993

[Folic Acid Reference Standard (Control 921) of National Institute of Health Sciences].

Folic acid was tested for the preparation of "Folic Acid Reference Standard (Control 921)". The quality of the raw material was examined and compared with the previous Folic Acid Reference Standard (Control 862). Analytical data obtained were as follows: water content, 7.52%; free amines, 0.1%; infrared spectrum, the same as that of the JP Reference Standard; thin-layer chromatography, three impurities were detected; high-performance liquid chromatography (HPLC), two impurities were detected; assay, 101.2% by spectrophotometry at 550 nm and 100.4% by HPLC. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 921).

Chromatography, High Pressure Liquid↗
PubMed2006

Folic acid and its metabolites modulate IGF-I receptor gene expression in colon cancer cells in a p53-dependent manner.

The insulin-like growth factor-I receptor (IGF-IR) has an important role in colorectal cancer development and progression. IGF-IR displays a potent anti-apoptotic activity and is overexpressed in primary tumors and colon cancer-derived cell lines. Folic acid, a member of the vitamin B family, is a chemopreventive agent whose deficiency has been linked to an enhanced colon cancer risk. The present study was aimed at testing the hypothesis that part of the modulatory effect of folic acid on malignant transformation may be attributed to its ability to regulate IGF-IR gene expression. Regulation of IGF-IR gene expression by folic acid was assessed using western blots, RT-PCR, transient transfections and chromatin immunoprecipitation assays. Activation of the IGF-IR signaling pathway was evaluated by measuring phosphorylation of ERK, and apoptosis was assayed using poly (ADP-ribose) polymerase cleavage and annexin V-FITC staining. Results obtained showed that folic acid induced a dose-dependent decrease in IGF-IR protein and mRNA levels in the HCT116 +/+ colon cancer cell line. This effect was associated with a significant reduction in IGF-IR promoter activity. Similar effects were elicited by the folic acid metabolites dihydrofolic acid and tetrahydrofolic acid. In addition, folic acid abrogated the IGF-I-stimulated phosphorylation of the downstream signaling molecule ERK1/2 and exhibited a pro-apoptotic activity. Moreover, folic acid induced a significant decrease in Sp1 binding to the IGF-IR promoter region. Finally, folic acid had no effect in wild-type p53-depleted HCT116 -/- and Caco-2 cells. In conclusion, the mechanism of action of folic acid involves regulation of IGF-IR gene expression. The ability of folic acid to downregulate the IGF-I signal transduction pathway may allow the micronutrient to function as a chemopreventive agent. Folic acid deficiency, on the other hand, may lead to increased IGF-IR gene expression, with ensuing pathological activation by endocrine and/or autocrine/paracrine IGF-I.

Apoptosis↗
PubMed1978

Effect of an implanted Walker tumour on metabolism of folic acid in the rat.

The metabolism of 2-[14C] folic acid has been studied in rats with an implanted Walker 256 tumour and in a closely matched group of controls. In animals with tumours, more of the labelled folic acid is converted to 10-formyltetrahydrofolate and 10-formylfolate than in normal animals. No 5-methyltetrahydrofolate could be detected in tumour tissue, or in the livers of tumour-bearing animals. When a mixture of 2-[14C]- and 3',5',9-[3H]-folic acid is given to tumour-bearing rats a similar pattern of metabolites is found. There is apparenly less scission of the folate molecule in tumour-bearing rats than in normal rats.

Administration, Oral↗
PubMed2001

Folic acid supplements during pregnancy and risk of miscarriage.

BACKGROUND: Although taking supplements that contain 400 microg of folic acid before and during early pregnancy reduces a woman's risk for having a baby with a neural-tube defect (NTD), the effects of such supplements on other pregnancy outcomes remain unclear. We examined whether the use of such supplements affects the occurrence of miscarriage. METHODS: Participants were women in China who had taken part in a recent folic acid campaign to prevent NTDs and who had registered in this campaign before they became pregnant for the first time. We examined the risk for miscarriage among women who had confirmed pregnancies and who had or had not taken pills containing only 400 microg of folic acid before and during early pregnancy. RESULTS: The overall rate of miscarriage was 9.1% (2155/23806). The rates of miscarriage among women who had and had not taken folic acid pills before and during the first trimester were 9.0% and 9.3%, respectively (risk ratio 0.97 [95% CI 0.84-1.12]). The distributions of gestational age at pregnancy diagnosis and at miscarriage were similar for both groups of women. INTERPRETATION: In this population-based study of a cohort of women whose use of folic acid supplements while pregnant had been previously documented and who had been pregnant for the first time, we found no evidence that daily consumption of 400 microg of folic acid before and during early pregnancy influenced their risk for miscarriage.

Abortion, Spontaneous↗
PubMed2000

Increased plasma homocyst(e)ine after withdrawal of ready-to-eat breakfast cereal from the diet: prevention by breakfast cereal providing 200 microg folic acid.

OBJECTIVE: We tested the hypothesis that cessation of habitual ingestion of breakfast cereals would be associated with elevated plasma homocyst(e)ine concentrations. We anticipated that those subjects who reported consuming breakfast cereals containing 100 to 400 ,microg of folic acid per serving before entering the study would achieve higher plasma homocyst(e)ine concentrations if, in addition to their regular diet, they began ingesting a daily serving of breakfast cereal that contained less than 10 microg of folic acid per serving. DESIGN: Seventy-nine subjects consumed a daily serving of breakfast cereal containing either < 10 microg or folic acid per serving (placebo) or breakfast cereal containing 200 microg of folic acid per serving (folic acid fortified). RESULTS: Cessation of intake of commercially available breakfast cereal was associated with homocyst(e)ine elevation. Breakfast cereal containing 200 microg folic acid per day was sufficient to maintain the homocyst(e)ine lowering effects of commercial cereals. CONCLUSIONS: Habitual consumption of commercially available fortified breakfast cereals, usually containing 100 to 400 microg folic acid per serving, had significant homocyst(e)ine lowering effects as shown by the homocyst(e)ine increase after cessation of habitual intake of commercial breakfast cereal. Substitution of breakfast cereal containing only 200 microg folic acid per day was sufficient to maintain the homocyst(e)inelowering effects of commercial cereals.

Aged↗
PubMed2003

Sequence-specific DNA damage induced by ultraviolet A-irradiated folic acid via its photolysis product.

DNA damage mediated by photosensitizers participates in solar carcinogenesis. Fluorescence measurement and high-performance liquid chromatography analysis demonstrated that photoirradiated folic acid, one of the photosensitizers in cells, generates pterine-6-carboxylic acid (PCA). Experiments using 32P-labeled DNA fragments obtained from a human gene showed that ultraviolet A-irradiated folic acid or PCA caused DNA cleavage specifically at consecutive G residues in double-stranded DNA after Escherichia coli formamidopyrimidine-DNA glycosylase or piperidine treatment. The amount of 8-oxo-7,8-dihydro-2(')-deoxyguanosine formed through this DNA photoreaction in double-stranded DNA exceeded that in single-stranded DNA. Kinetic studies suggested that DNA damage is caused mainly by photoexcited PCA generated from folic acid rather than by folic acid itself. In conclusion, photoirradiated folic acid generates PCA, which induces DNA photooxidation specifically at consecutive G residues through electron transfer. Excess intake of folic acid supplements may increase a risk of skin cancer by solar ultraviolet light.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Reduction of homocysteine levels in coronary artery disease by low-dose folic acid combined with vitamins B6 and B12.

An increased plasma homocysteine concentration is a risk factor for atherosclerosis. Folic acid lowers homocysteine but the optimal dose in patients with coronary artery disease (CAD) is unclear. This placebo-controlled, single-blind, dose-ranging study evaluates the effect of low-dose folic acid on homocysteine levels in 95 patients aged 61 +/- 11 years (mean +/- SD) with documented CAD. Patients in each group were given either placebo or 1 of 3 daily supplements of folic acid (400 microg, 1 mg, or 5 mg) for 3 months. Each active treatment arm also received 500 microg vitamin B12 and 12.5 mg vitamin B6. Total plasma homocysteine levels were measured after 30 and 90 days. Folic acid 400 microg reduced homocysteine levels from 13.8 +/- 8.8 to 9.6 +/- 2.0 micromol/L at 90 days (p = 0.001). On 1- and 5-mg folic acid, levels decreased from 13.0 +/- 6.4 to 9.8 +/- 4.0 micromol/L (p = 0.001) and from 14.8 +/- 6.9 to 9.7 +/- 3.3 micromol/L (p < 0.001), respectively. The decrease was similar in all treatment groups. There was no significant change with placebo. Although the sample size is small, these findings suggest that daily administration of 400 microg/day folic acid combined with vitamin B12 and vitamin B6 may be equivalent to higher doses in reducing homocysteine levels in patients with CAD.

Coronary Disease↗
PubMed1998

Effect of folic acid on thymidylate synthase and thymidine kinase in regenerating rat liver after partial hepatectomy.

The effects of folic acid on liver regeneration after partial hepatectomy were investigated. The injection of folic acid inhibited the increases in the activities of thymidylate synthase and thymidine kinase in regenerating rat liver at 24 h after partial hepatectomy, with a concomitant reduction in DNA content. Northern blot analysis showed that this inhibition was due to the delay of the elevation of the mRNA levels of thymidylate synthase and thymidine kinase after partial hepatectomy. At 48 and 72 h, after partial hepatectomy, the thymidylate synthase activities in the folic acid injected rats increased to about 1.9- and 1.7-fold the corresponding control level, respectively, while thymidine kinase activities were similar to the control. Immunoblotting assay indicated that the increases in the thymidylate synthase activity at 48 and 72 h after partial hepatectomy were caused by a three fold increase in its protein level. Folic acid suppressed chymotryptic hydrolysis of thymidylate synthase. These suggest that folic acid increases the protein level of thymidylate synthase, at least in part, through protection against proteolysis.

Animals↗
PubMed1983

Phenytoin and folic acid: individualized drug-drug interaction.

The effect of folic acid supplementation on the disposition of phenytoin and the resultant loss of seizure control in a male folate-deficient epileptic is reported. Due to the increase in tonic-clonic seizures after the initiation of folic acid (1 mg, orally) the sodium phenytoin dosage was increased by 130 mg until control was achieved. Because of these dosage changes, the Vmax and Km were calculated before and after initiation of the folic acid. The Vmax remained relatively the same, but the Km decreased after folate supplementation.

Drug Interactions↗