Clinical trial: B vitamins improve health in patients with coeliac disease living on a gluten-free diet.

BACKGROUND: Patients with coeliac disease living on a gluten-free diet show vitamin deficiency and reduced subjective health status. AIM: To study the biochemical and clinical effects of B vitamin supplementation in adults with longstanding coeliac disease. METHODS: In a double blind placebo controlled multicentre trial, 65 coeliac patients (61% women) aged 45-64 years on a strict gluten-free diet for several years were randomized to a daily dose of 0.8 mg folic acid,0.5 mg cyanocobalamin and 3 mg pyridoxine or placebo for 6 months. The outcome measures were psychological general well-being (PGWB) and the plasma total homocysteine (tHcy) level, marker of B vitamin status. RESULTS: Fifty-seven patients (88%) completed the trial. The tHcy level was baseline median 11.7 micromol/L (7.4-23.0), significantly higher than in matched population controls [10.2 micromol/L (6.7-22.6) (P < 0.01)]. Following vitamin supplementation, tHcy dropped a median of 34% (P < 0.001), accompanied by significant improvement in well-being (P < 0.01), notably Anxiety (P < 0.05) and Depressed Mood (P < 0.05) for patients with poor well-being. CONCLUSIONS: Adults with longstanding coeliac disease taking extra B vitamins for 6 months showed normalized tHcy and significant improvement in general well-being, suggesting that B vitamins should be considered in people advised to follow a gluten-free diet.

Plasma homocysteine and markers of bone metabolism in psychogeriatric patients.

OBJECTIVE: In recent studies high plasma total homocysteine (tHcy) levels were reported to be associated with increased risk of osteoporotic fractures. In elderly psychogeriatric patients there is a high frequency of elevated plasma tHcy concentration. The present study therefore investigates the association between plasma tHcy concentration and markers of bone metabolism in psychogeriatric patients. MATERIAL AND METHODS: A total of 152 psychogeriatric patients were investigated and plasma tHcy and its major determinants (serum folate, serum cobalamin and renal function) were measured. Osteocalcin and crosslaps were chosen as markers of bone metabolism. RESULTS: Bone markers (crosslaps and osteocalcin) were increased in elderly patients with dementia compared to patients without dementia. Stepwise multiple regression analysis showed that plasma tHcy concentration made only a small contribution to the prediction of crosslaps in serum, whereas plasma tHcy concentration was not an independent predictor of serum osteocalcin. CONCLUSIONS: The present study does not provide support for the hypothesis that a moderately increased plasma tHcy concentration is a risk factor for impaired bone metabolism.

Asymmetric dimethylarginine and total homocysteine in plasma after oral methionine loading.

BACKGROUND: Elevation of homocysteine (Hcy) and asymmetric dimethylarginine (ADMA) in plasma are believed to be involved in the pathogenesis of cardiovascular disease (CVD). In humans, oral methionine loading results in acute elevation of plasma Hcy. This is associated with impaired NO-dependent vasodilatation, a mechanism that may explain the relationship between elevated Hcy and risk of CVD. ADMA, an endogenous competitive inhibitor of NO-synthase, may be elevated in plasma of patients with CVD. It was proposed that ADMA is synthesized in a methionine-dependent reaction which also forms Hcy. In this study plasma total homocysteine (tHcy) and ADMA concentrations were measured before and after oral methionine loading of human subjects. METHODS: Plasma tHcy and ADMA levels were measured in 12 healthy males (age 32-58 years) before and after oral loading with L-methionine (100 mg/kg body weight in orange juice). RESULTS: At noon, 4 h after methionine loading, tHcy and ADMA levels (35.4 +/- 10.9 and 0.80 +/- 0.13 micromol/L, mean +/- SD) were significantly higher than the corresponding values obtained at noon the day before (15.6 +/- 7.4 and 0.63 +/- 0.10 micromol/L, both p<0.001). Noon values 4 h after methionine loading were also significantly higher than values obtained immediately before the methionine load (13.7 +/- 5.9 and 0.66 +/- 0.10 micromol/L, both p<0.001). Reinvestigation of 8 of 12 subjects showed that at 4 and 8 h after compared with levels immediately before methionine loading there was a significant increase in tHcy (28.4 +/- 10.2 and 33.45 +/- 11.1 vs. 10.8 +/- 3.3 micromol/L, both p<0.001). However, the corresponding ADMA levels did not increase (0.73 +/- 0.17 and 0.76 +/- 0.22 vs. 0.70 +/- 0.10 micromol/L, both not significant). CONCLUSIONS: No clear evidence was found to support the supposition that methionine-induced hyperhomocysteinaemia may be accompanied by elevated levels of ADMA, an endogenous competitive NO-synthase inhibitor that may represent an alternative pathogenic mechanism for homocysteine-associated impairment of endothelial NO-dependent functions.

Hyperhomocysteinaemia is not associated with increased levels of asymmetric dimethylarginine in patients with ischaemic heart disease.

BACKGROUND: Elevated plasma total homocysteine appears to be related to endothelial dysfunction and impaired nitric oxide production. We aimed to investigate [1] whether elevated levels of plasma total homocysteine are associated with high plasma levels of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, and [2] whether reduction of plasma total homocysteine levels by folate and vitamin B supplementation lowers plasma concentration of asymmetric dimethylarginine. MATERIALS AND METHODS: Sixty patients with ischaemic heart disease and with plasma total homocysteine levels of 15.0 micromol L-1 were randomized to open therapy with folic acid, pyridoxine and cyancobalamin for 3 months (n = 30) or to no treatment (n = 30). Samples were also obtained from 34 patients with plasma total homocysteine levels of 8.0 micromol L-1 on admission. RESULTS: Plasma asymmetric dimethylarginine concentrations in patients with elevated total homocysteine levels were not significantly higher (0.68 +/- 0.19 micromol L-1) than in patients with low total homocysteine levels (0.61 +/- 0.10 micromol L-1; P = 0.08). Plasma asymmetric dimethylarginine level in the vitamin supplemented group was 0.65 +/- 0.12 micromol L-1 before, and 0.64 +/- 0.12 micromol L-1 after 3 months of vitamin supplementation (NS). Plasma asymmetric dimethylarginine levels were correlated with serum cystatin C levels (P < 0.001). CONCLUSION: A nonsignificant trend to increased plasma levels of asymmetric dimethylarginine in patients with high plasma total homocysteine levels may be explained by concomitant subtle renal dysfunction. Substantial reduction of plasma total homocysteine did not affect the level of plasma asymmetric dimethylarginine.

The effect of vitamin B12 on total plasma homocysteine concentration in folate-replete hemodialysis patients.

AIM: Results from several studies indicate that the total homocysteine (tHcy) concentration in plasma is an independent risk factor for cardiovascular disease in hemodialysis patients. Folic acid is the established mainstay of homocysteine-lowering treatment, but since such treatment does not normalize plasma tHcy concentration in hemodialysis patients, it is of importance to search for additional therapy. METHODS: Twenty-eight folate-replete hemodialysis patients were randomized to 2 equally sized groups, a treatment group and a control group. The treatment group received vitamin B12 tablets at a dose of 2 mg 3 times a week for 6 weeks (after each dialysis session) while the control group received no such treatment. Blood samples were collected before and at the end of the treatment period for analysis of tHcy in plasma and vitamin B12, methylmalonic acid as well as folate in serum. RESULTS: At the end of the study period, serum vitamin B12 concentrations were significantly higher in the treatment group than in the control group. Plasma tHcy concentrations decreased significantly in both groups during the study period. However, there was no difference between the responses of the 2 groups. CONCLUSION: The results of this open, randomized controlled study did not support the hypothesis that treatment with oral vitamin B12 has considerable homocysteine-lowering effect in folate-replete hemodialysis patients.

Role of impaired renal function as a cause of elevated plasma homocysteine concentration in psychogeriatric patients.

In previous studies a high frequency of elevated plasma tHcy concentrations has been observed in psychogeriatric patients (40-50%), but the main cause of these increased concentrations could not be established with certainty. Impaired renal function could partly contribute to elevated plasma tHcy concentrations in psychogeriatric patients. Therefore, in the present study, cystatin C was used as a sensitive marker for glomerular filtration. A linear regression analysis including age, blood folate, serum cobalamin, serum cystatin C and serum creatinine showed that only serum creatinine (p<0.001) and blood folate (p<0.001) independently predicted plasma tHcy concentration. However, about 44% of the patients with elevated plasma tHcy concentrations had signs of reduced glomerular filtration rate, as judged by increased serum cystatin C, whereas only about 13% of the patients with normal concentrations of plasma tHcy had signs of reduced glomerular filtration rate. This finding indicates that renal impairment may to some extent contribute to the elevated plasma tHcy concentration, even though serum cystatin C did not independently predict plasma tHcy concentration.

Markers for the functional availability of cobalamin/folate and their association with neuropsychiatric symptoms in the elderly.

Cobalamin/folate deficiency is common in elderly subjects and may lead to psychiatric symptoms, but even more often it increases the severity of other organic and non-organic mental diseases. This paper reviews the literature relevant for markers of cobalamin/folate status and their relation to neuropsychiatric symptoms in the elderly. Plasma homocysteine, a marker of cobalamin/folate status, is frequently increased in psychogeriatric patients. Among markers of cobalamin/folate status, plasma homocysteine shows the best association with neuropsychiatric dysfunction.

Improvement of cognitive functions after cobalamin/folate supplementation in elderly patients with dementia and elevated plasma homocysteine.

OBJECTIVES: To investigate the effect of cobalamin/folate supplementation on cognitive function in elderly patients with dementia. METHOD: The cobalamin/folate status of the patients was evaluated by measuring plasma homocysteine, serum methylmalonic acid, serum cobalamin and blood folate. Thirty-three patients were studied and repeatedly assessed with the Mini-Mental State Examination (MMSE) and 'A short cognitive performance test for assessing memory and attention' (SKT) during vitamin substitution. RESULTS: Patients with mild-moderate dementia and elevated plasma homocysteine levels improved clinically with increased test scores after vitamin substitution, while severely demented patients and patients with normal plasma homocysteine levels did not improve clinically. CONCLUSIONS: Plasma homocysteine may be the best marker for detecting treatable cobalamin/folate deficiency in patients with dementia.

Hyperhomocysteinemia and changed plasma thiol redox status in chronic obstructive pulmonary disease.

Reduced and total homocysteine, cysteine, glutathione and cysteinylglycine in plasma were investigated in 19 patients with chronic obstructive pulmonary disease and in 29 healthy subjects. The purpose was to examine the influence of pro-oxidant activity caused by the lung disease on the metabolism of homocysteine and other plasma thiols. We observed a decreased concentration of reduced glutathione and a decreased ratio of reduced/total glutathione in the patients compared to the healthy individuals, which supports the hypothesis of an association between free radicals and pathogenesis in some lung diseases. We also observed an increased total plasma homocysteine. The influence of a possible extracellular pro-oxidant activity on the concentration of total plasma homocysteine is discussed.

Interaction of metals and thiols in cell damage and glutathione distribution: potentiation of mercury toxicity by dithiothreitol.

In the present study, we have investigated the effects of extracellular redox status and metal/thiol interactions on glutathione distribution in HeLa cell cultures. No effects were seen on glutathione distribution after the addition of different thiols, whereas the pro-oxidant copper ions affected glutathione distribution in several ways. The addition of dithiothreitol (DTT) but not the other thiols potentiated the effects of mercury ions on glutathione distribution and cell toxicity. In the presence of DTT, increased intra- and extracellular glutathione concentrations were noted already at 0.05 micromol/l, which was below the previously reported toxicity threshold for mercury ions in blood. Likewise DTT potentiated the effects of copper ions on glutathione distribution and cell toxicity, whereas the addition of DTT to cell cultures with a non-metal thiol reactive agent (hydroquinone) or an oxidative agent (hydrogen peroxide) did not affect glutathione distribution or cell toxicity. Thus, it seems as the synergistic effects between DTT and thiol reactive agents only apply to metal ions.

Plasma total homocysteine concentration in nephrotic patients with idiopathic membranous nephropathy.

BACKGROUND: The atherothrombotic risk pattern of the nephrotic syndrome resembles that of hyperhomocysteinemia. However, the effect of nephrotic range proteinuria on homocysteine metabolism has never been studied. METHODS: The study included 11 male nephrotic patients with idiopathic membranous nephropathy who underwent a treatment trial with adrenocorticotrophic hormone and 11 male non-nephrotic, renal function-matched control subjects. The nephrotic patients were studied before and after the treatment, which induced a marked reduction in urinary protein excretion and a moderate improvement in renal function in all cases. RESULTS: Plasma total homocysteine (tHcy) concentration did not change significantly during treatment, whereas the nephrotic patients had significantly lower tHcy than the non-nephrotic patients (14.2 +/- 3.4 micromol/l vs 19.0 +/- 5.4 micromol/l). tHcy correlated significantly with serum concentrations of creatinine (r = 0.53, P < 0.05) and albumin (r = 0.43, P < 0.05), glomerular filtration rates (GFRs) (iohexol clearances) (r = -0.42, P < 0.05) and urinary albumin excretion (r = -0.47, P < 0.05). CONCLUSION: The expected tHcy-lowering effect of improved renal function may have masked a tHcy-elevating effect due to reduced proteinuria leading to no net change in tHcy during treatment. The notion of an increase in tHcy associated with remission of the nephrotic syndrome is in accordance with the significantly lower tHcy in the nephrotic renal patients compared with the non-nephrotic renal function-matched patients, and the relationships between tHcy and serum albumin concentrations as well as urinary albumin excretion. Thus, the results of this small study suggest that nephrotic range proteinuria directs homocysteine metabolism towards a decrease in tHcy. However, the findings need to be confirmed in larger patient populations and in different varieties of the nephrotic syndrome.

Isolated liver perfusion permits administration of high doses of chemotherapeutic agents. Comparison with hepatic artery infusion.

Tumor cells are dependent on glutamine metabolism and acivicin, which is a selective glutamine antagonist, has been shown to effectively retard tumor growth in several malignancies. However, systemic treatment with acivicin is associated with significant side effects. The purpose of the present study was to examine whether use of an in vivo isolated liver perfusion model may allow administration of lethal doses of acivicin and compare it to regional infusion of acivicin in the hepatic artery. Five days after tumor inoculation, acivicin was administered by an isolated liver perfusion model or by regional infusion via the hepatic artery. It was found that regional infusion of acivicin (5 and 10 mg/kg) via the hepatic artery caused systemic illness and diarrhea, and all animals in this group died within 3 days. In contrast, we observed no signs of systemic illness, diarrhea or hepatocellular injury in rats receiving isolated liver perfusion with or without acivicin (10 mg/kg) administration. Noteworthy, we found that isolated perfusion with acivicin reduced the glutamine content in liver tumors by 39% compared to perfusion with control medium. In line with this, it was found that isolated perfusion with acivicin (10 mg/kg) inhibited tumor growth in the liver. Taken together, this study suggests that application of the isolated liver perfusion model avoids the toxic and lethal effects of high doses of chemotherapy, herein acivicin, and may provide a useful approach to treat liver tumors in vivo.

[Homocysteine and methylmalonic acid as markers of cobalamin/folate status. The association to neuropsychiatric symptoms in the elderly is explored]. / Homocystein och metylmalonsyra markörer för kobalamin-/folatstatus. Relationen till neuropsykiatriska symtom hos äldre belyses.

Cobalamin/folate deficiency in elderly subjects may lead to psychiatric symptoms. Most studies concerning the relation between mental disorders in the elderly and deficiencies of cobalamin and folate have used methods that determine the blood concentrations of these vitamins, which might not reflect vitamin status in the tissues. Two new markers, plasma homocysteine and serum methylmalonic acid, have attracted growing interest since they are considered to reflect the functional status of cobalamins and folates in the tissues. This review summarizes present findings concerning the different markers for cobalamin/folate deficiency as well as their association with functional parameters of the central nervous system such as cognitive and behavioral performance. Plasma homocysteine seems to be much more closely associated with neuropsychiatric dysfunction than is plasma methylmalonic acid.

Effects of inhibition of glycation and oxidative stress on the development of cataract and retinal vessel abnormalities in diabetic rats.

PURPOSE: To study effects of inhibition of glycation, and oxidative stress on the development of cataract and retinal vessel abnormalities in diabetic rats. METHODS: Diabetes was induced in male Wistar rats with streptozocin (STZ; 60 mg/kg BW, i.p.). Diabetic as well as strain matched control rats were fed 1) a normal diet, 2) addition of aminoguanidine in the drinking water (0.5 g/l for diabetic rats and 1.0 g/l for control rats) or 3) probucol in the pellets (1% w/w). After 6 months, the number of acellular vessels, endothelial cells and pericytes were counted in trypsin digested retinal vessel preparations, and the total retinal tissue amount of glutathione (GSH) and cysteine was measured with HPLC. RESULTS: Cataract formation occurred after 13 weeks in diabetic animals compared with 17 weeks for those treated with aminoguanidine, and 16 weeks for those treated with probucol (p < 0.001 in both cases). Aminoguanidine inhibited the formation of acellular collapsed capillary strands, 9 (3-14) vs. 18 (12-262) (median, range) per quadrant in untreated diabetic rats (p = 0.004), while probucol did not have any effect. Neither aminoguanidine, nor probucol influenced the endothelial/pericyte ratio. Diabetes caused a reduction in the GSH/cysteine ratio (10.7 +/- 0.6 vs. 15.3 +/- 1. 5) (mean +/- SD; p < 0.001). Probucol partly restored this imbalance (p < 0.05) whereas aminoguanidine did not. CONCLUSIONS: The results indicate that cataract formation in diabetes involves both glycation and oxidative stress processes. The reduced formation of acellular collapsed capillary strands by aminoguanidine suggests a potential role for glycation in vascular damage. The positive effect of probucol on cysteine/GSH metabolism imbalance indicates that derangements of one of the retinal defense systems against oxidative stress can be normalized by antioxidants.

Long-standing hyperglycemia in C57BL/6J mice does not affect retinal glutathione levels or endothelial/pericyte ratio in retinal capillaries.

Free radicals have been suggested to play a role in the development of diabetic retinopathy. The aim of the present study was to examine whether the metabolic perturbations caused by high-fat feeding of two strains of mice, the C57BL6/J mice and the NMRI mice, interfere with one of the free radical enzyme defense systems in the retina, i. e., glutathione (GSH), and whether morphological changes occur in the retinal vessels. C57BL/6J mice and NMRI mice were fed a high-fat diet (55%) for 18 months. High-fat fed mice of both strains developed overweight, hyperinsulinemia, and hyperlipidemia. In addition, the high-fat fed C57BL/6J mice also developed sustained hyperglycemia for at least 15 months. The C57BL/6J mice had lower retinal GSH levels than the NMRI mice, both when given a normal diet (29.6+/-1.2 vs. 37.1+/-1.4 nmol/mg protein; p<0.01) and when given a high-fat diet (27.0+/-1.6 vs. 34.7+/-2.6 nmol/mg protein; p<0.05). Despite the long-standing hyperglycemia, hyperinsulinemia and hyperlipidemia in the C57BL/6J mice, high-fat feeding did not cause any changes in the retinal tissue levels of GSH (27.0+/-1.6 vs. 29. 6+/-1.2 nmol/mg protein) or cysteine (7.61+/-0.63 vs. 6.80+/-0.59 nmol/mg protein). Similarly, high-fat feeding did not affect retinal GSH or cysteine levels in NMRI mice. No light microscopical retinal vessel changes were seen, either in C57BL/6J or in NMRI mice. The study therefore shows that long-standing metabolic perturbations induced by dietary obesity do not induce signs of retinopathy in two different strains of mice. Further studies are needed to explore whether this is explained by increased expression of protecting systems making these strains of mice resistant to effects of oxidative stress.

Plasma total homocysteine levels in postmenopausal women with unstable coronary artery disease.

An elevated plasma total homocysteine (tHcy) level is considered a risk factor for coronary artery disease (CAD), but the relationship between plasma tHcy and well-defined CAD in women is still unclear. Plasma tHcy concentrations and the covariates serum folate, vitamin B12, and creatinine were analysed in 157 angiographically examined postmenopausal women with unstable CAD and in 101 healthy controls. At coronary angiography, 16% had normal vessels and 84% had coronary atherosclerosis. Mean plasma tHcy concentration (micromol/l, 95% confidence interval) did not differ in patients compared to controls (13.1 (12.3-13.8) vs. 12.5 (11.6-13.5)) or in patients with or without coronary atherosclerosis (13.3 (12.4-14.1) vs. 12.0 (10.8-13.2)). A trend to an increasing plasma tHcy with increasing degree of coronary atherosclerosis was attenuated after adjustment for age and the previous mentioned covariates. Odds ratio for the risk of coronary artery disease and coronary atherosclerosis in hyperhomocysteinemic patients (> or =90th percentile in controls) was approximately 3. However, the confidence interval included unity in half of the groups and the significance was therefore difficult to judge. Receiver operating characteristics showed age to be the only variable with a significant discriminatory ability regarding the presence of coronary atherosclerosis (area 0.77). Mild hyperhomocysteinemia seems not to be related to the risk of unstable CAD in postmenopausal women. The trend towards higher plasma tHcy with increasing degree of coronary atherosclerosis may be a marker of the disease. In future studies adjustment for age and the other three covariates should be considered.

Treatment of cobalamin deficiency in dementia, evaluated clinically and with cerebral blood flow measurements.

We investigated the relation between cobalamin deficiency, clinical changes and brain function in dementia patients. On admittance to the clinic, 24 patients had cobalamin deficiency, and dementia with additional symptoms of delirium. During cobalamin supplementation, the patients underwent repeated regional cerebral blood flow (rCBF) studies, psychiatric evaluations, and in some cases assessment with MMSE and the Organic Brain Syndrome scale. Fifteen patients who showed mild to moderate dementia improved clinically, and also showed a concomitant increase in their general CBF after treatment. In contrast, 9 patients who were severely demented showed no obvious clinical improvement, and no general blood flow change, although some regional flow increases were seen in sensory motor areas. We conclude that symptoms which probably indicated superimposed delirium such as clouding of consciousness, disorientation and clinical fluctuation, responded to the vitamin B12 supplementation, while the underlying dementia condition remained basically unchanged. The clinical improvement was also mirrored in general and focal rCBF changes.

Severe retinopathy in type 1 diabetic patients is not related to the level of plasma homocysteine.

The vascular-injuring amino acid homocysteine was previously shown to be increased in plasma in type 1 diabetic patients with clinical signs of nephropathy. Previous studies have also shown an inconsistent relationship between the development of diabetic nephropathy and retinopathy, indicating different pathogenetic mechanisms. In this study, plasma homocysteine was measured in 25 type 1 diabetic patients with a well-characterized form of severe retinopathy. Furthermore, a group of 24 type 1 diabetic patients with similar age at onset of diabetes and diabetes duration with no or minimal background retinopathy were investigated, in order to determine whether plasma homocysteine levels are different from those in patients with severe retinopathy. Patients with severe retinopathy did not have higher plasma levels of homocysteine (13.9 micromol/L; 5.9-30.7, median and range) than those without retinopathy (10.4 micromol/L; 5.7-18.9). Within the group of patients with severe retinopathy, increased homocysteine levels were confined to the patients (19.9 micromol/L; 10.0-30.7, n=9) with serum creatinine levels > 100 micromol/L, compared to those patients (9.6; 5.9-14.3 micromol/L, n=15) with a serum creatinine below 100 micromol/L. None of the patients without or with minimal background retinopathy had serum creatinine levels > 100 micromol/L. We conclude that diabetic retinopathy is not associated with increased plasma homocysteine levels, but plasma homocysteine accumulates, probably owing to reduced glomerular filtration, in diabetic patients with signs of nephropathy. In these patients, the promoting effect of nephropathy on the development of retinopathy does not seem to be mediated through homocysteine.