In vivo assay of folate receptors in nonfunctional pituitary adenomas with 99mTc-folate SPECT/CT.

UNLABELLED: The objective of this study was to evaluate the in vivo assay of folate receptors in nonfunctional pituitary adenomas using preoperative (99m)Tc-folate SPECT/CT and Western blot analysis (WBA) of surgical specimens as the standard. METHODS: Fifty-six patients (29 men, 27 women; age range, 29-82 y) with clinically nonfunctional pituitary adenomas on MRI underwent preoperative imaging using 666 MBq (18 mCi) of (99m)Tc-folate. SPECT/CT images and whole-body and lateral head planar images were acquired approximately 2 h after injection. Surgical resection took place within a week. WBA on a portion of the excised specimens assessed folate receptor expression in 49 patients. Attenuation-corrected (99m)Tc-folate SPECT/CT images were assessed qualitatively and quantitatively (maximal adenoma counts to background), with WBA as a standard. RESULTS: Integrated CT was useful for uptake localization and assisted region-of-interest placement. Qualitative interpretation of planar imaging yielded a sensitivity of 81% and specificity of 72%. Qualitative SPECT/CT yielded a sensitivity of 94% and specificity of 61%. Receiver-operating-characteristic curve analysis of quantitative uptake yielded a tumor-to-background cutoff ratio of 3.5, with a sensitivity of 81% and specificity of 83%. Scalp uptake yielded consistent results (over the brain, neck, and choroid plexus) for background when SPECT/CT misalignment artifacts were avoided. Detection of pituitary uptake on anterior-posterior and lateral images was hampered by facial uptake, which varied between patients. CONCLUSION: SPECT/CT of (99m)Tc-folate is an accurate method of assaying folate receptors in vivo and may provide a quantitative marker for identifying folate receptor-positive tumors. This method may also prove beneficial in selecting patients for folate-targeted therapy of clinically nonfunctional pituitary adenomas, for which there is currently no medical therapy.

Atherosclerotic risk among children taking antiepileptic drugs.

Epilepsy is a common chronic neurological disorder that requires long-term or sometimes lifetime therapy. Recent evidence indicates that prolonged use of antiepileptic drugs (AEDs) might modify some vascular risk factors; however, the influence of AED therapy on the development of atherosclerosis has been the subject of controversy. Some epidemiological studies have reported a higher prevalence of ischemic vascular disease among epileptic patients on AEDs, while in other studies the mortality due to atherosclerosis-related cardiovascular disease in treated epileptics has been observed to be lower than in the general population. The etiology of atherosclerosis-related vascular diseases in epileptic patients has not been fully clarified. Since atherosclerotic vascular alterations may start early in life, this review focuses on major atherogenic risk factors among epileptic children, including altered metabolism of homocysteine, disordered lipid profiles, and increased lipoprotein (a) serum levels, as well as thyroid hormone deficiency with special concern for clinical implications.

Synthesis and biological activity of a 3,4,5-trimethoxybenzoyl ester analogue of epicatechin-3-gallate.

Despite presenting bioavailability problems, tea catechins have emerged as promising chemopreventive agents because of their observed efficacy in various animal models. To improve the stability and cellular absorption of tea polyphenols, we developed a new catechin-derived compound, 3- O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin (TMECG), which has shown significant antiproliferative activity against several cancer cell lines, especially melanoma. The presence of methoxy groups in its ester-bound gallyl moiety drastically decreased its antioxidant and prooxidant properties without affecting its cell-antiproliferative effects, and the data indicated that the 3-gallyl moiety was essential for its biological activity. As regards its action mechanism, we demonstrated that TMECG binds efficiently to human dihydrofolate reductase and down-regulates folate cycle gene expression in melanoma cells. Disruption of the folate cycle by TMECG is a plausible explanation for its observed biological effects and suggests that, like other antifolate compounds, TMECG could be of clinical value in cancer therapy.

Effect of folic acid on methotrexate induction of sulfotransferases in rats.

Our earlier investigation showed that MTX is an inducer of rat and human sulfotransferases. Here we report that folic acid treatment inhibited MTX induction of aryl sulfotransferase (AST-IV) in female rat liver and hydroxysteroid sulfotransferase (STa) in male rat liver. This is important for understanding the clinical mechanisms of MTX.

Homocysteine levels are unaffected by metformin treatment in both nonpregnant and pregnant women with polycystic ovary syndrome.

BACKGROUND: Women with polycystic ovary syndrome have elevated homocysteine levels. Elevated homocysteine levels associate with pregnancy complications. Women with polycystic ovary syndrome are often treated with metformin, a drug that may increase homocysteine levels. Hence, we investigated the effect of metformin treatment on homocysteine levels in nonpregnant and pregnant women with polycystic ovary syndrome. METHODS: Two prospective randomized placebo-controlled studies included women with polycystic ovary syndrome in a university hospital setting. Sixty-three infertile women were treated with metformin 1,000 mg bid or placebo for 16 weeks and 38 pregnant women with metformin 850 mg bid or placebo from the first trimester and throughout pregnancy. All the women had polycystic ovary syndrome and all participants received diet and lifestyle advice, and oral folate and vitamin B12 substitution, and a daily oral multivitamin tablet. The main outcome measures were serum levels of homocysteine, folate, and vitamin B12. RESULTS: Serum homocysteine levels were unaffected by metformin treatment both in nonpregnant and pregnant women with polycystic ovary syndrome. However, in nonpregnant women both serum folate and vitamin B12 levels decreased with treatment. At inclusion in nonpregnant women, serum homocysteine levels associated negatively with serum levels of folate and methyl malonic acid and positively with free testosterone index. No such associations were seen in pregnant women. CONCLUSIONS: Metformin treatment in women with polycystic ovary does not increase serum homocysteine levels in the nonpregnant or the pregnant state.

Perinatal choline influences brain structure and function.

Choline is derived not only from the diet, but also from de novo synthesis. It is important for methyl-group metabolism, the formation of membranes, kidney function, and neurotransmission. When deprived of dietary choline, most adult men and postmenopausal women develop signs of organ dysfunction (fatty liver or muscle damage) and have a decreased capacity to convert homocysteine to methionine. Choline is critical during fetal development, when it influences stem cell proliferation and apoptosis, thereby altering brain structure and function (memory is permanently enhanced in rodents exposed to choline during the latter part of gestation).

Influence of different dietary levels of zinc on performance, vitamin B12, and blood parameters in lambs.

This experiment was conducted to investigate the influence of different dietary levels of zinc (Zn) on performance, vitamin B12, and blood parameters in lambs. Thirty six cannulated Poll Dorset x Small-tailed Han wether lambs were assigned randomly to four treatment groups: The control group, which was supplemented with 0.30 mg Co/kg dry matter (DM) to the basal diet; and the low-, medium- and high-Zn supplemented groups, supplementation of 50, 100, and 150 mg Zn/kg DM to the control diet, respectively. Lambs were housed in individual pens and the experiment lasted for 70 days. There was no significant difference in body weight gain and feed/gain between different treatment groups. The high-Zn supplemented lambs showed lower vitamin B12 concentrations in both ruminal fluid and plasma, and higher methylmalonic acid and homocysteine concentrations in plasma compared with the control and low-Zn supplemented groups (p < 0.05). No significant difference was observed in these biochemical values between the control, the low-, and the medium-Zn supplemented groups (p > 0.05). Plasma folate concentration, glucose, and heme-dependent blood parameters were not influenced by dietary zinc level. It was concluded that the higher level of zinc supplementation had a negative effect on vitamin B12 in lambs. Higher inclusion level of dietary zinc could inhibit vitamin B12 synthesis in the rumen of lambs.

Disruption of methyl group metabolism by ethanol.

Recent studies have focused on establishing a link between the pathogenesis of ethanol and the disruption of metabolic pathways in the liver. Ethanol alters hepatic methionine metabolism, leading to perturbation of S-adenosylmethionine-dependent transmethylation. Therefore, the supply of metabolically related nutrients such as folate may play a role in the hepatotoxic effects of ethanol.

Severe encephalopathy induced by the first but not the second course of high-dose methotrexate mirrored by plasma homocysteine elevations and preceded by extreme differences in pretreatment plasma folate.

Plasma homocysteine has recently been associated with the occurrence of methotrexate-related neurotoxicity. We observed extreme elevations of homocysteine in a 9-year-old boy presenting with leukemia treated with the ALL-BFM 95 protocol. Coma occurred at about the 71st hour from the first methotrexate administration, and lasted for 30 h but MRI and CT studies showed no intracranial pathology. The second course of high-dose methotrexate was administered with no complications. Homocysteine areas under the curve (AUC) were calculated as the sum of areas of rectangles during the 6-hour intervals from T(0) to T(72) hours (AUC(0--72)) and methotrexate AUCs were evaluated using MW/PHARM 3.3 software. The AUC of homocysteine during the first, toxic course was 5.2 times higher than AUC during the second administration, whereas AUC of methotrexate also differed by a factor of 5. Plasma concentrations of folate prior to the first and the second courses, respectively, were 4.4 versus 45 micromol/l making this difference the most striking discriminator between the two courses. Mutation analysis showed that the patient was heterozygous for the C 677 T mutation in the MTHFR gene. We suggest that plasma homocysteine, pretreatment plasma folate and possibly the presence of MTHFR mutations may be biomarkers of methotrexate toxicity and possibly its antifolate effect targeted towards the tumor as well.

Fighting infection: an ongoing challenge, part 1.

Since the beginning of time, infections have been a major cause of disability and death of humans in every part of the world. For centuries, little was known about what caused infection, how to prevent infection, or how to cure infection. With the discovery of sulfa and penicillin in the 1930s, the ability to fight infection became reality. During the next six decades, antimicrobials were developed to fight bacterial, fungal, and viral infections. It truly seemed as if the battle against infection was won, until the rapid and global spread of drug resistance began to threaten the effectiveness of all currently available antimicrobials. A new phase of the war against infection began, and the search for methods of reducing the spread of drug resistance began. Today, it is apparent that identifying the agents of infection, understanding how antimicrobials are targeted against specific infectious organisms, and practicing the judicious application of antimicrobials will help reduce the threat of continued escalation of antimicrobial resistance. Part 1 of this three-part series will provide an overview of how antimicrobials are designed to target specific agents of infection and how drug resistance develops. Parts 2 and 3 will examine individual antibacterial, antifungal, and antiviral agents and the recommendations for their appropriate use.

Supplementation with mixed fruit and vegetable juice concentrates increased serum antioxidants and folate in healthy adults.

OBJECTIVE: Epidemiological studies have shown that low plasma levels of antioxidant micronutrients, which are commonly found in fruit and vegetables, are associated with increased risk for diseases such as heart disease, cancer, metabolic disorders and the like. The aim of this study was to monitor the dietary habits of a group of healthy, middle-aged, men and women and to assess the effect of supplementation with a natural phytonutrient preparation from fruits and vegetables, on plasma levels of various antioxidant micronutrients and oxidative stress assessed by measuring 8-oxodGuo (8-oxo-7,8-dihydro-2'-deoxyguanosine) in urine. METHODS: The study followed a double-blind randomized cross-over design involving 59 healthy men and women (40-60 years of age). The supplement or a placebo was given to two groups for a total period of 14 weeks (crossover week 7). Blood levels of beta-carotene, vitamin C, vitamin E, selenium and folate were measured at 0, 7 and 14 weeks. Fruit and vegetable consumption was monitored by means of a retrospective food frequency questionnaire at week 0, 7 and 14. Urinary 8-oxodGuo was also determined at these time points. RESULTS: Significant increases in blood nutrient levels after active supplementation were observed for beta-carotene, vitamin C, vitamin E, selenium and folate. Ranges measured, after supplementation, often fell into those associated with a reduced risk for disease. Our data suggests that, although generally health conscious, participants still fell short of the recommended five portions of fruit and vegetables per day. No significant group changes were noted for 8-oxodGuo concentration in urine. CONCLUSION: Supplementation with mixed fruit and vegetable juice concentrates effectively increased plasma levels of important antioxidant nutrients and folate.

Laxative treatment elevates plasma homocysteine: a study on a population-based Swedish sample of old people.

OBJECTIVES: Elevated plasma homocysteine might indicate an increased risk of cancer, and cardiovascular and neurological diseases. The homocysteine level depends on the supply of folate and cobalamine, and constipation and/or laxative treatment might compromise this supply. The present study examined the impact of constipation and laxative treatment on the blood levels of homocysteine, folate and cobalamine in a population-based sample of aged people, including consideration of frailty and impaired renal function, both of which may also influence the homocysteine level. METHODS: The study was based on biochemical tests in 341 females and 183 males aged 82 years or older. The concentrations of homocysteine (plasma), folate, cobalamine and urea (serum) were measured in subjects with and without ongoing treatment with laxative drugs. Values were adjusted for age, gender and frailty, as well as for clinical diagnoses and drug therapies known to affect homocysteine levels. RESULTS: Homocysteine levels were increased and those of folate reduced in aged subjects on laxatives. Homocysteine remained elevated after adjusting for frailty and various neurological disorders. There was no significant effect on homocysteine and folate in constipated subjects without laxatives.

Therapeutic potential of folate uptake inhibition in Plasmodium falciparum.

Plasmodium falciparum parasites resistant to the combination sulfadoxine-pyrimethamine are spreading in Africa, particularly in East Africa. This is a matter of concern because there are no other affordable drugs available. This article provides the evidence indicating that sulfadoxine-pyrimethamine resistance can be reversed in vitro and discusses how this information might be exploited to extend the therapeutic lifetime of sulfadoxine-pyrimethamine in vivo.

Effects of short-term treatment with metformin on serum concentrations of homocysteine, folate and vitamin B12 in type 2 diabetes mellitus: a randomized, placebo-controlled trial.

OBJECTIVE: Metformin is a key treatment option in type 2 diabetes. However, metformin may decrease vitamin B12 levels and increase levels of homocysteine, a cardiovascular risk factor. We investigated whether 16 weeks of treatment with metformin affects serum concentrations of homocysteine, folate and vitamin B12 in subjects with type 2 diabetes treated with insulin. DESIGN: Placebo-controlled, randomized trial. MEASUREMENTS: at baseline and 16 weeks later. SETTING: This trial was conducted in the outpatient clinics of three general hospitals in The Netherlands. SUBJECTS: A total of 745 patients with type 2 diabetes, treated with insulin and not known with a contraindication for the use of metformin, were approached; 390 gave informed consent and entered the study. Thirty-seven subjects dropped out (12 placebo and 25 metformin users). INTERVENTION: Addition of metformin or placebo to insulin therapy. PRIMARY OUTCOME PARAMETERS: Serum homocysteine, folate, vitamin B12, indices of glycaemic control and body weight. RESULTS: Amongst those who completed 16 weeks of treatment, metformin use, as compared with placebo, was associated with an increase in homocysteine of 4% (0.2 to 8; P=0.039) and with decreases in folate [-7% (-1.4 to -13); P=0.024] and vitamin B12 [-14% (-4.2 to -24); P<0.0001]. In addition, the increase in homocysteine could be explained by the decreases in folate and vitamin B12. CONCLUSION: In patients with type 2 diabetes, 16 weeks of treatment with metformin reduces levels of folate and vitamin B12, which results in a modest increase in homocysteine. The clinical significance of these findings remains to be investigated.

Chemiluminescence inhibition assay for folic acid using flow injection analysis.

A new flow injection method for the determination of folic acid is described. A fast oxidation reaction occurred when folic acid was mixed with potassium ferricyanide generating ferrocyanide which then inhibited the chemiluminescent reaction of ferricyanide and luminol in alkaline medium. The decrease of chemiluminescence intensity was correlated with the folic acid concentration in the range 0.1-21 microg/mL; the detection limit for the assay was 0.03 microg/mL (3sigma). A complete analysis of folic acid, including sampling and washing, could be performed within 2 min with a relative standard deviation of less than 4.0%. The proposed method has been applied successfully to the determination of folic acid in pharmaceutical preparations.

Oral and transdermal estrogens both lower plasma total homocysteine in male-to-female transsexuals.

Plasma total homocysteine (tHcy) levels are on average lower in women versus men, indicating an estrogenic effect. Oral estrogens (absorbed via the liver) may be hypothesized to have stronger effects on hepatic homocysteine metabolism than transdermal estrogens. We randomly assigned 30 male-to-female transsexuals (20-44 years old) to 4 months' administration of oral ethinyl estradiol (n=15) or transdermal 17beta-estradiol (n=15), both with the antiandrogen cyproterone acetate (CA). Ten other male controls were treated with CA only. At baseline and after 2 and 4 months, plasma tHcy was analyzed in conjunction with plasma folate. Oral ethinyl estradiol and transdermal 17beta-estradiol similarly reduced plasma tHcy (geometric mean 10.6 micromol/l [95% CI 8.2-13.9] to 7.5 [6.5; 8.8], and 11.3 [8.1; 16.4] to 8.4 [6.5; 11.1]; P<0.001 for both), whereas CA had no effects. No effects were found on folate levels. Thus, oral and transdermal estrogens decrease plasma tHcy to a similar degree (by geometric mean -26%), which suggests that a hepatic mechanism is unlikely to play an important role in the decline of tHcy levels.

Alcohol, folate, methionine, and risk of incident breast cancer in the American Cancer Society Cancer Prevention Study II Nutrition Cohort.

Recent studies suggest that the increased risk of breast cancer associated with alcohol consumption may be reduced by adequate folate intake. We examined this question among 66,561 postmenopausal women in the American Cancer Society Cancer Prevention Study II Nutrition Cohort. A total of 1,303 incident cases had accrued during the first 5 years of follow-up. Cox proportional hazards models and stratified analysis were used to examine the relationship between alcohol, dietary and total folate intake, multivitamin use, dietary methionine, and breast cancer. We observed an increasing risk of breast cancer with increasing alcohol consumption (P for trend = 0.01). In the highest category of consumption (15 or more grams of ethanol/day), the risk of breast cancer was 1.26 (95% confidence interval, 1.04-1.53) compared with nonusers. We observed this association with higher alcohol consumption for in situ, localized, and regional disease. We found no association between risk of breast cancer and dietary folate, total folate, multivitamin use, or methionine intake. Furthermore, we found no evidence of an interaction between levels of dietary folate (P for interaction = 0.10) or total folate (P for interaction = 0.61) and alcohol. Nor did we find evidence of an interaction between alcohol consumption and recent or long-term multivitamin use (P for interaction = 0.27). Our results are consistent with a positive association with alcohol but do not support an association with folate or methionine intake or an interaction between folate and alcohol intake on risk of breast cancer.

Nutritional advice to increase soluble fibre intake does not change plasma folate or homocysteine in men with angina: a randomised controlled trial.

OBJECTIVE: To study the effect of advice to increase dietary soluble fibre, including fruit and vegetables, on plasma folate and homocysteine in men with angina. DESIGN: Data were collected on a subset of subjects from the Diet and Angina Randomised Trial (DART II). In a randomised (2 x 2) factorial design, subjects received advice on either, neither or both interventions to: (1) increase soluble fibre intake to 8.0 g day(-1) (fruit, vegetables and oats); (2) increase oily fish intake to 2 portions week(-1). Those who received soluble fibre advice were compared with those who did not. Subjects were genotyped for C677T variant 5,10-methylenetetrahydrofolate reductase (MTHFR). SETTING/SUBJECTS: Seven hundred and fifty-three male angina patients were recruited from general practice. RESULTS: Plasma homocysteine concentrations were at the upper end of the normal range (median 11.5, 25% 9.4, 75% 14.0 micromol l(-1)). Baseline intake of fruit and vegetables was positively correlated with plasma folate (r(s) = 0.29, P < 0.01). Smokers had lower intakes of fruit and vegetables, lower plasma folate and higher homocysteine (all P < 0.01). Homozygotes for variant MTHFR had higher homocysteine concentrations at low plasma folate (P < 0.01). Reported intakes of fruit and vegetables and estimated dietary folate increased in the intervention group (ca. +75 g day(-1), P < 0.01 and ca. +20 g day(-1), P < 0.05, respectively). However, neither plasma folate (baseline/follow-up 4.5 vs. 4.4 microg l(-1), P = 0.40) nor homocysteine (baseline/follow-up 11.7 vs. 11.7 micromol l(-1), P = 0.31) changed. CONCLUSIONS: Plasma homocysteine, a cardiovascular risk factor, is influenced by MTHFR genotype, plasma folate and smoking status. Dietary advice successfully led to changes in fruit and vegetable intake, but not to changes in plasma folate or homocysteine, possibly because the fruits and vegetables that were chosen were not those richest in folate.