DACH-LIGA homocystein (german, austrian and swiss homocysteine society): consensus paper on the rational clinical use of homocysteine, folic acid and B-vitamins in cardiovascular and thrombotic diseases: guidelines and recommendations

The association between dietary intake of folate and physical activity with psychological dimensions of depressive symptoms among students from Iran

Depression in students is a major public health problem. Although several risk factors associated with depression have been identified, the cause of depression is still not clear. Several studies have demonstrated that physical activity and nutrient intake, such as increased levels of B vitamins in serum, decrease symptoms of depression. The aim of this study was to investigate the association between physical activity and dietary intake of vitamins B₆, B₉, and B₁₂ and symptoms of depression among postgraduate students. The results of this study suggest that intake of vitamin B9 may modulate the total score of Center for Epidemiological Studies Depression Scale (CES-D) and two subscales of the CES-D including depressive affect and interpersonal difficulties. This study also showed that moderate/high levels of physical activity were inversely and significantly associated with symptoms of depression (total scores) and three subscales of the CES-D including depressive affect, positive affect, and somatic complaints.

Homocysteine in dogs with systemic inflammatory response syndrome

OBJECTIVES

To compare serum concentrations of homocysteine in healthy dogs and those fitting the criteria for systemic inflammatory response syndrome and to compare these values to commonly measured B-vitamins.

METHODS

Study dogs were classified into non-infectious systemic inflammatory response syndrome or sepsis groups and blood was drawn on Day 1 of the patient's hospitalisation for measurement of serum homocysteine, folate and cobalamin concentrations. Homocysteine concentration was measured in 51 clinically healthy dogs to serve as the control group.

RESULTS

A statistically significant difference was found between the homocysteine concentrations of the healthy group when compared to non-infectious systemic inflammatory response syndrome and sepsis groups. Homocysteine values were not correlated with folate, cobalamin or APPLEfast severity scores. Homocysteine concentrations were significantly lower in sick dogs when compared to the control group, which is dissimilar to the human population.

CLINICAL SIGNIFICANCE

The clinical significance of homocysteine changes in critically ill dogs is currently unknown.

The effect of homocysteine-lowering with B-vitamins on osteoporotic fractures in patients with cerebrovascular disease: substudy of VITATOPS, a randomised placebo-controlled trial

BACKGROUND

Homocysteine has been postulated as a novel, potentially reversible risk factor for osteoporosis and related fractures. We evaluated whether homocysteine-lowering therapy with B-vitamins in patients with symptomatic cerebrovascular disease reduced the incidence of osteoporotic fractures.

METHODS

VITAmins To Prevent Stroke (VITATOPS) was a prospective randomised double-blind placebo-controlled trial in which 8,164 patients with recent (within 7 months) stroke or transient ischemic attack were randomly allocated to double-blind treatment with one tablet daily of either placebo (n = 4,075) or B-vitamins (folic acid 2 mg, vitamin B6 25 mg, vitamin B12 500 μg; n = 4,089). Patients were reviewed every six months. Any osteoporotic fracture and osteoporotic hip fractures were secondary outcome events, and were reviewed by a masked adjudication committee. Analysis was by intention to treat. Logistic regression was used to identify independent predictors of fracture.

RESULTS

Participants had a mean age of 62.6 years (SD 12.5 years) and 64% were male, 42% of Western European descent and 75% were functionally independent (Oxford Handicap Scale of two or less). After a median duration of 2.8 years therapy and 3.4 years follow-up, there was no significant difference in the incidence of any osteoporotic fracture between participants assigned B-vitamins (67 [1.64%]) and placebo (78 [1.91%]; risk ratio [RR] 0.86, 95% confidence interval [CI] 0.62-1.18) or the incidence of hip fractures (34 [0.83%] B-vitamins vs. 36 [0.88%] placebo; RR 0.94, 95% CI 0.59-1.5). There was no significant impact of B-vitamin therapy on time to first fracture. Baseline homocysteine levels did not predict any osteoporotic fracture (p =0.43). Independent predictors of any osteoporotic fracture were female sex, age > 64 years, Western European ethnicity and use of anti-osteoporosis medication at randomization (all p < 0.01).

CONCLUSIONS

Once daily treatment with B-vitamins had no effect on incidence of osteoporotic fractures during a median of 3.4 years follow-up in patients with cerebrovascular disease. A modest effect of B-vitamin therapy is not excluded due to the low numbers of fracture outcome events.

Big-endothelin 1 (big ET-1) and homocysteine in the serum of dogs with chronic kidney disease

This study was aimed at determining the serum concentration of homocysteine (Hcy) and big endothelin-1 (big ET-1, the precursor of endothelin) in dogs with chronic kidney disease (CKD) with and without hypertension, proteinuria and inflammation, in order to explore their role as biomarkers of hypertension associated with CKD. Hcy and big ET-1 were measured using an enzyme-linked immunosorbent assay and an enzymatic cyclic reaction, respectively, in dogs with CKD staged, as proposed by the International Renal Interest Society (IRIS), using serum creatinine, urinary protein to creatinine (UPC) ratio and systolic blood pressure, and classified as affected or not by inflammation based on the serum concentration of C-reactive protein (CRP). Serum Hcy was significantly higher in dogs of IRIS stages II, III and IV compared with controls and in proteinuric compared with non-proteinuric dogs. No differences relating to the degree of hypertension or to the CRP concentration were found. Serum big ET-1 significantly increased in dogs of IRIS stage IV compared with controls, in proteinuric compared with non-proteinuric dogs, in dogs with severe hypertension compared with those without hypertension, and in dogs with increased CRP compared to those with normal CRP concentrations. Hcy only correlated with serum creatinine but big ET-1 significantly correlated with serum creatinine, UPC ratio, systolic blood pressure, and increased CRP. In conclusion, both Hcy and big ET-1 increase in dogs with CKD. Although further research is needed, big ET-1, but not Hcy, may also be considered as a biomarker of hypertension.

Intervention with vitamins in patients with nonproliferative diabetic retinopathy: a pilot study

Background

The purpose of this study was to determine whether a combination of vitamins B6, B9, and B12 is an effective intervention for reducing the signs and symptoms of nonproliferative diabetic retinopathy.

Methods

Ten subjects with type 2 diabetes mellitus (n = 20 eyes) with clinically diagnosed mild to moderate nonproliferative diabetic retinopathy were recruited from a private practice ophthalmology clinic for this open-label, uncontrolled, prospective six-month study. Metanx® vitamin tablets (containing 3 mg L-methylfolate calcium, 35 mg pyridoxal-5′-phosphate, and 2 mg methylcobalamin) were administered at a dosage of two tablets daily. Primary outcome indicators were the percent change in mean retinal sensitivity threshold measured by macular microperimetry and the percent change in mean central retinal thickness measured by spectral-domain optical coherence tomography.

Results

Three subjects were lost to follow-up. In the remaining seven subjects, two of 14 eyes had foveal edema that prevented microperimetry measurements due to poor fixation. The remaining 12 eyes showed a nonlinear improvement in mean threshold retinal sensitivity (P < 0.001). Overall change in mean central retinal thickness in 14 eyes was linear (R² = 0.625; P = 0.034), with a significant reduction between one and six months (P = 0.012).

Conclusion

In this pilot study, the Metanx intervention appeared to have some beneficial effects with respect to reducing retinal edema and increasing light sensitivity in subjects with nonproliferative diabetic retinopathy.

Excess dietary methionine does not affect fracture healing in mice

Background

An elevated serum concentration of homocysteine (hyperhomocysteinemia) has been shown to disturb fracture healing. As the essential amino acid, methionine, is a precursor of homocysteine, we aimed to investigate whether excess methionine intake affects bone repair.

Material/Methods

We analyzed bone repair in 2 groups of mice. One group was fed a methionine-rich diet (n=13), and the second group received an equicaloric control diet without methionine supplementation (n=12). Using a closed femoral fracture model, bone repair was analyzed by histomorphometry and biomechanical testing at 4 weeks after fracture. Blood was sampled to measure serum concentrations of homocysteine, the bone formation marker osteocalcin, and the bone resorption marker collagen I C-terminal crosslaps

Results

Serum concentrations of homocysteine were significantly higher in the methionine group than in the control group, while serum markers of bone turnover did not differ significantly between the 2 groups. Histomorphometry revealed no significant differences in size and tissue composition of the callus between animals fed the methionine-enriched diet and those receiving the control diet. Accordingly, animals of the 2 groups showed a comparable bending stiffness of the healing bones.

Conclusions

We conclude that excess methionine intake causes hyperhomocysteinemia, but does not affect fracture healing in mice.

The impact of genetic and environmental factors on homocysteine levels in preterm neonates

BACKGROUND

Hyperhomocysteinemia may be associated with vascular complications in adults. Whereas pediatric thrombosis risk peaks in neonates, data on homocysteine (Hcy) levels assessed in term and preterm infants during the perinatal period are scarce. In the present study, we aimed to establish Hcy reference values for preterm infants and study their potential associations with the early post-natal health status. Plasma Hcy and hematocrit levels and MTHFR polymorphisms (C677T and A1298C substitution) were studied in a large cohort of preterm infants in a tertiary referral medical center during an 18-month period. Data were collected on maternal history and delivery as well as on post-natal complications.

RESULTS

The study cohort included 167 infants whose mean gestational age was 30.98 ± 2.34 weeks (range: 26-36 weeks), mean birth weight 1327.6 ± 327 g, and mean Hcy level 7.99 ± 3.27 (range: 2.2-21.2) µmol/L. Maternal intake of folic acid was inversely associated with the babies' Hcy levels (P = 0.0001). Increased Hcy levels positively correlated with birth weight, gestational age (P < 0.005), total number of pregnancies (P = 0.012), and presence of MTHFR polymorphism. Higher Hcy levels were associated with feeding (P = 0.008), especially total parenteral nutrition (P = 0.0001). There was no correlation between Hcy levels and any vascular post-natal complications.

CONCLUSIONS

During their post-natal hospitalization, preterm infants may have relatively high, that is, within the adult normal range, Hcy levels which are influenced by genetic and environmental factors. Despite the fact that no correlation was found between Hcy levels and post-natal complications, these associations should be further studied.

Serum homocysteine and methylmalonic acid concentrations in Chinese Shar-Pei dogs with cobalamin deficiency

Cobalamin deficiency is suspected to be hereditary in Chinese Shar-Pei dogs (Shar-Peis), and inherited causes of cobalamin deficiency may affect the cellular processing of cobalamin. In humans, a defect of the two main cobalamin-dependent intracellular enzymes (i.e., methionine synthase and methylmalonyl-CoA mutase) may lead to hyperhomocysteinemia and hypermethylmalonic acidemia. The aim of this retrospective study was to evaluate serum homocysteine (HCY) and methylmalonic acid (MMA) concentrations in cobalamin-deficient Shar-Peis and dogs of six other breeds. Serum samples (n=297) from cobalamin-deficient dogs (Shar-Peis, German Shepherd dogs, Labrador Retrievers, Yorkshire Terriers, Boxers, Cocker Spaniels, and Beagles) were analyzed for serum HCY and MMA concentrations. A Fisher's exact test was used to evaluate if cobalamin deficiency in Shar-Peis is associated with hyperhomocysteinemia. Serum HCY and MMA concentrations were higher in cobalamin-deficient Shar-Peis compared to cobalamin-deficient dogs of the six other breeds (P<0.0001). Hyperhomocysteinemia was associated with cobalamin deficiency in Shar-Peis (P=0.009). In addition, serum HCY and MMA concentrations did not differ between cobalamin-deficient German Shepherd dogs with and without exocrine pancreatic insufficiency (EPI), a potential cause of secondary cobalamin deficiency. These findings suggest that the function of the two intracellular cobalamin-dependent enzymes is impaired in Shar-Peis with cobalamin deficiency.

Prevalence of hyperhomocysteinaemia and its major determinants in rural Chinese hypertensive patients aged 45–75 years

We aimed to investigate the prevalence of hyperhomocysteinaemia (total plasma homocysteine (tHcy) ≥ 10 μmol/l) and its major determinants in rural Chinese hypertensive patients. A cross-sectional investigation was carried out in Lianyungang of Jiangsu province, China. This analysis included 13 946 hypertensive adults. The prevalence of hyperhomocysteinaemia was 51·6 % (42·7 % in women and 65·6 % in men). The OR of hyperhomocysteinaemia were 1·52 (95 % CI 1·39, 1·67) and 2·32 (95 % CI 2·07, 2·61) for participants aged 55–65 and 65–75 v. 45–55 years; 1·27 (95 % CI 1·18, 1·37) for participants with a BMI ≥ 25 v. < 25 kg/m2; 1·14 (95 % CI 1·06, 1·23) for participants with v. without antihypertensive treatment; 1·09 (95 % CI 1·00, 1·18) for residents inland v. coastal; 0·89 (95 % CI 0·82, 0·97) and 0·83 (95 % CI 0·74, 0·92) for participants with moderate and high v. low physical activity levels; 1·54 (95 % CI 1·41, 1·68) and 2·47 (95 % CI 2·17, 2·81) for participants with a glomerular filtration rate 60–90 and < 60 v. ≥ 90 ml/min per 1·73 m2; and 1·20 (95 % CI 1·07, 1·35) and 3·81 (95 % CI 3·33, 4·36) for participants with CT and TT v. CC genotype at methylenetetrahydrofolate reductase 677C>T polymorphism, respectively. Furthermore, higher tHcy concentrations were observed in smokers of both sexes (men: geometric mean 12·1 (interquartile range (IQR) 9·2–14·5) v. 11·9 (IQR 9·3–14·0) μmol/l, P= 0·005; women: geometric mean 10·3 (IQR 8·3–13·0) v. 9·6 (IQR 7·8–11·6) μmol/l, P= 0·010), and only in males with hypertension grade 3 (v. grade 1 or controlled blood pressure) (geometric mean 12·1 (IQR 9·2–14·4) v. 11·7 (IQR 9·2–14·0), P= 0·016) and in male non-drinkers (yes v. no) (geometric mean 12·3 (IQR 9·4–14·8) v. 11·7 (IQR 9·1–13·9), P= 0·014). In conclusion, there was a high prevalence of hyperhomocysteinaemia in Chinese hypertensive adults, particularly in the inlanders, who may benefit greatly from tHcy-lowering strategies, such as folic acid supplementation and lifestyle change.

Elevated plasma homocysteine levels in patients with multiple sclerosis are associated with male gender

Elevated homocysteine (Hcy) levels exert several neurotoxic actions and vascular dysfunctions that may be involved in pathogenesis and progression of multiple sclerosis (MS). The effective role of Hcy in MS however remains to be determined. The aim of this work was to compare plasma Hcy levels in MS patients and neurological disease controls (NDC) and to evaluate their relationships with clinical and demographic variables. In this cross-sectional study, we examined plasma Hcy levels in 217 patients with MS [53 clinically isolated syndromes (CIS) suggestive of MS, 134 relapsing remitting (RR), 23 secondary progressive (SP) and seven primary progressive (PP) MS], recruited among patients attending a tertiary clinical center in southern Italy and in 219 age/sex-matched controls. Median Hcy levels were slightly higher in MS patients compared to NDC (9.1 μmol/l; range, 3.4-35.9 vs. 8.6, range 3.5-27.4; p = 0.02). Median Hcy concentrations were increased in males more than in females in the MS population (10.4 vs. 8.4; p < 0.0001), whereas no differences across genders were found in NDC (9.1 vs. 8.5). Hcy levels were higher in male MS patients compared to the male NDC patients (p = 0.001). Patients with CIS had lower Hcy (7.5 μmol/l; p = 0.004) compared to patients with RR (9.5 μmol/l), SP (10.1 μmol/l) and PP (9.9 μmol/l). Median Hcy concentration was higher in patients with disease duration longer than 22 months (9.7 vs. 8.6 μmol/l; p = 0.02). Plasma Hcy levels are increased in patients with definite MS. Higher Hcy levels are associated with male sex, suggesting a role of Hcy in neurodegenerative processes of MS, which are prominent in male patients.

Plasma Homocysteine is Not Related to the Severity of Microangiopathy in Secondary Raynaud Phenomenon

Introduction:

The role of elevated homocysteine in primary and secondary Raynaud phenomenon (RP) and in patients with atherosclerosis has been reported controversially. In secondary RP due to connective tissue disease specific alterations of nailfold capillaries might be present. An association between these microvascular changes and homocysteine has been suggested.

Aim:

The aim of this study was to determine whether homocysteine level differs between patients with primary and secondary RP and to test the hypothesis that homocysteine or other cardiovascular risk factors are associated with specific features of microangiopathy in secondary RP.

Patients and Methods

Eighty-one consecutive patients with RP referred for vascular assessment were studied by nailfold capillaroscopy. Homocysteine, C-reactive protein and cholesterol were measured and other cardiovascular risk factors and comorbidities assessed.

Results:

Homocysteine, C-reactive-protein and cholesterol levels did not differ between patients with primary (n=60) and secondary RP (n=21). Likewise, no differences in the prevalence of cardiovascular risk factors and comorbidities were found. In secondary RP no correlation was found between microvascular involvement and homocysteine or C-reactive protein.

Conclusion:

Plasma homocysteine is not different in patients with either primary or secondary RP and is therefore not a marker for the distinction of these diseases. The extent of microvascular involvement in secondary RP does not correlate with plasma homocysteine.

Vitamin B6 and cardiovascular disease

While overt vitamin B6 deficiency is not a frequent finding nowadays in medical practice, evidence suggests that insufficiency of this vitamin is rather widespread in a quite large portion of the population such as the elderly or in not unusual conditions such as that of alcohol addiction. Moreover, a mild deficiency in B6 vitamin is a state that may be associated with an increased risk of cardiovascular disease. Epidemiologic evidence from case control and prospective studies have suggested that low dietary intake or reduced blood concentrations of vitamin B6 is associated with an increased risk of cardiovascular disease, although most recent trials demonstrated the ineffectiveness of vitamin B6 supplementation on the prevention of cardiovascular events recurrence. Due to limited and somewhat inconsistent data together with the ample variety of critical functions in which vitamin B6 is involved in the human body, it is very challenging to attempt at establishing a cause and effect relationship between vitamin B6 and risk of cardiovascular disease as it is to delineate the exact mechanism(s) by which vitamin B6 may modulate such risk. In the present chapter we review the currently available knowledge deriving from both epidemiological and mechanistic studies designed to define potential candidate mechanisms for the association of vitamin B6 impairment and risk of cardiovascular disease development.

Enzymatic and non-enzymatic antioxidative effects of folic acid and its reduced derivates

A great part of the population appears to have insufficient folate intake, especially subgroups with higher demand, as determined through more sensitive methods and parameters currently in use. As the role of folate deficiency in congenital defects, e.g. in cardiovascular and neurodegenerative diseases, and in carcinogenesis has become better understood, folate has been recognized as having great potential to prevent these many disorders through folate supplementation or fortification for the general population. Folates are essential cofactors in the transfer and utilization of one-carbon groups in the process of DNA-biosynthesis with implications for genomic repair and stability. Folate acts indirectly to lower homocysteine levels and insures optimal functioning of the methylation cycle. Homocysteine was shown to be an independent risk factor for neurodegenerative and cardiovascular disease, which includes peripheral vascular disease, coronary artery disease, cerebrovascular disease and venous thrombosis. In fact, it was long believed that the beneficial effects of folate on vascular function and disease are related directly to the mechanism of homocysteine-diminution. Recent investigations have, however, demonstrated beneficial effects of folates unrelated to homocysteine-diminution, suggesting independent properties. One such mechanism could be free radical scavenging and antioxidant activity, as it is now recognized that free radicals play an important role in the oxidative stress leading to many diseases. It was found that folic acid and, in particular, its reduced derivates act both directly and indirectly to produce antioxidant effects. Folates interact with the endothelial enzyme NO synthase (eNOS) and, exert effects on the cofactor bioavailability of NO and thus, on peroxynitrite formation. Folate metabolism provides an interesting example of gene-environmental interaction.

Association of plasma homocysteine with self-reported sleep apnea is confounded by age: results from the national health and nutrition examination survey 2005-2006

High levels of plasma homocysteine are implicated in the pathogenesis of cardiovascular diseases especially if accompanied by sleep apnea, but a direct pathogenetic link between plasma homocysteine levels and obstructive sleep apnea is debatable. This association can have far-reaching public health implications considering the inverse association between folate and plasma homocysteine. We used data from the 2005-2006 cycle of the National Health and Nutrition Examination Survey (NHANES) to test the hypothesized associations. Of the 4490 subjects included in analysis, 177 reported sleep apnea. Age-standardized and design-effect-corrected prevalence rates were differential across gender, plasma homocysteine, and red cell folate status. Plasma homocysteine was positively correlated with age (r = 0.38, P < 0.0001). Multivariate analyses using sociodemographic and clinical covariates demonstrated that plasma homocysteine levels retained their respective associations with self-reported sleep apnea in all models except when age was included as a covariate. Our results demonstrate that the claimed association of plasma homocysteine with sleep apnea may be confounded by age.

Status of B-vitamins and homocysteine in diabetic retinopathy: association with vitamin-B12 deficiency and hyperhomocysteinemia

Diabetic retinopathy (DR) is a common cause of blindness. Although many studies have indicated an association between homocysteine and DR, the results so far have been equivocal. Amongst the many determinants of homocysteine, B-vitamin status was shown to be a major confounding factor, yet very little is known about its relationship to DR. In the present study, we, therefore, investigated the status of B-vitamins and homocysteine in DR. A cross-sectional case–control study was conducted with 100 normal control (CN) subjects and 300 subjects with type-2 diabetes (T2D). Of the 300 subjects with T2D, 200 had retinopathy (DR) and 100 did not (DNR). After a complete ophthalmic examination including fundus fluorescein angiography, the clinical profile and the blood levels of all B-vitamins and homocysteine were analyzed. While mean plasma homocysteine levels were found to be higher in T2D patients compared with CN subjects, homocysteine levels were particularly high in the DR group. There were no group differences in the blood levels of vitamins B1 and B2. Although the plasma vitamin-B6 and folic acid levels were significantly lower in the DNR and DR groups compared with the CN group, there were no significant differences between the diabetes groups. Interestingly, plasma vitamin-B12 levels were found to be significantly lower in the diabetes groups compared with the CN group; further, the levels were significantly lower in the DR group compared with the DNR group. Higher homocysteine levels were significantly associated with lower vitamin-B12 and folic acid but not with other B-vitamins. Additionally, hyperhomocysteinemia and vitamin-B12 deficiency did not seem to be related to subjects' age, body mass index, or duration of diabetes. These results thus suggest a possible association between vitamin-B12 deficiency and hyperhomocysteinemia in DR. Further, the data indicate that vitamin-B12 deficiency could be an independent risk factor for DR.

Homocysteine and asymmetric dimethylarginine in relation to B vitamins in elderly people

OBJECTIVE

Homocysteine is a cardiovascular risk factor, its metabolism is influenced by certain B vitamins and it is associated with endothelial dysfunction probably due to impaired bioavailability of NO caused by homocysteine-induced accumulation of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase. On this basis, we investigated the cardiovascular risk factors homocysteine and ADMA in relation to vitamins B(6), B(12) and folate in elderly people.

METHODS

A total of 102 subjects were recruited and divided into three groups according to age: A (70-74y, n = 48), B (75-79y, n = 35) and C (≥80y, n = 19). Plasma levels of vitamin B(6) were determined with HPLC, vitamin B(12) and folate by RIA. Plasma concentrations of homocysteine were analyzed with HPLC and levels of ADMA were measured by ELISA.

RESULTS

Plasma levels of vitamins B(6), B(12) and folate were found to be adequate in 93, 67 and 55% of participants, respectively. This study showed a significant age-associated decrease in vitamins B(6) (A > B, A > C: p < 0.05), B(12) and folate (A > C: p < 0.05) in parallel to a significant age-related increase in the cardiovascular risk factors homocysteine (A < C, B < C: p < 0.05) and ADMA (A < B: p < 0.05; A < C: p < 0.001). Moreover, homocysteine was significantly negatively (p < 0.01) related to vitamins B(6), B(12) and folate, and significantly positively (p < 0.01) correlated to ADMA.

CONCLUSIONS

The significant correlation between homocysteine and ADMA observed in this study may be an important mechanism decreasing NO bioavailability and so causing endothelial dysfunction. Due to the significant relation of vitamins B(6), B(12) and folate to plasma homocysteine, these vitamins may thus indirectly influence endothelial function and cardiovascular risk in elderly people.

Antioxidant intake from diet and supplements and elevated serum C-reactive protein and plasma homocysteine concentrations in US adults: a cross-sectional study

Objective

To investigate the association of antioxidant intakes from diet and supplements with elevated blood C-reactive protein (CRP) and homocysteine (Hcy) concentrations.

Design

A cross-sectional study. The main exposures were vitamins C and E, carotene, flavonoid and Se intakes from diet and supplements. Elevated blood CRP and Hcy concentrations were the outcome measures.

Setting

The US population and its subgroups.

Subjects

We included 8335 US adults aged ≥19 years from the National Health and Nutrition Examination Survey 1999–2002.

Results

In this US population, the mean serum CRP concentration was 4·14 (95 % CI 3·91, 4·37) mg/l. Intakes of vitamins C and E and carotene were inversely associated with the probability of having serum CRP concentrations >3 mg/l in multivariate logistic regression models. Flavonoid and Se intakes were not associated with the odds of elevated serum CRP concentrations. The mean plasma Hcy concentration was 8·61 (95 % CI 8·48, 8·74) μmol/l. Intakes of vitamins C, E, carotenes and Se were inversely associated with the odds of plasma Hcy concentrations >13 μmol/l after adjusting for covariates. Flavonoid intake was not associated with the chance of elevated plasma Hcy concentrations.

Conclusions

These results suggest that high antioxidant intake is associated with lower blood concentrations of CRP and Hcy. These inverse associations may be among the potential mechanisms for the beneficial effect of antioxidant intake on CVD risk mediators in observational studies.

[Association of hyperhomocysteinemia with liver steatosis in patients with chronic hepatitis C]

BACKGROUND AND OBJECTIVES

Liver steatosis in chronic hepatitis C (CHC) is related to viral and metabolic factors and likely to genetic factors. The aim of this study was to know if hyperhomocysteinemia and methylenetetrahydrofolate reductase (MTHFR)-C677T polymorphisms are associated with liver steatosis in nonalcoholic patients with CHC.

PATIENTS AND METHOD

In 54 consecutive patients with CHC, alcohol consumption less than 40g/week, and no other causes of liver disease, a liver biopsy was performed. All variables were obtained at the time of biopsy. MTHFR-C677T was also performed in 128 healthy subjects, with age and gender similar to the patients.

RESULTS

Liver steatosis was found in 33 patients (61%), 30 of them having a mild degree. Hyperhomocysteinemia was more prevalent in patients with steatosis (61% vs 24%; p=0.008) and overweight tended to be more prevalent in the same patients (61% vs 33%; p=0.05). All patients with virus C genotype 3 had steatosis. Viral load, liver inflammatory and fibrosis score were not different in patients with and without steatosis. MTHFR-C677T polymorphism was similar in controls and cases and in cases with and without steatosis. A multiple logistic regression showed that hyperhomocysteinemia was associated with liver steatosis after adjustment for age and sex (OR: 3.94; 95% CI: 1.09-14.29), and adjustment for overweight (OR: 4.43; 95% CI: 1.27-15.51).

CONCLUSIONS

In nonalcoholic patients with CHC mild liver steatosis is frequent, and is associated with hyperhomocysteinemia. An association between steatosis and MTHFR-C677T polymorphism was not found.

Hyperhomocysteinemia is not associated with reduced bone quality in humans with hip osteoarthritis

BACKGROUND

Recent clinical and animal studies suggest that increased serum homocysteine (HCY) concentrations may be a risk factor for osteoporosis. In vitro studies showed that increasing HCY concentrations stimulate the activity of human osteoclasts. However, there is no data demonstrating that circulating HCY is related to structural and biomechanical properties of human bones. This study investigated the relationship between morphological as well as biomechanical bone properties and HCY serum concentrations in humans suffering from hip osteoarthritis (OA).

METHODS

Fasting blood samples and femoral heads were obtained from 94 males and females who underwent hip arthroplasty due to OA. Bones were assessed by dual energy X-ray absorptiometry (DXA), biomechanical testing (indentation method), and histomorphometry. Blood was collected for measurement of HCY, folate, vitamin B6, and vitamin B12. Subjects were classified as hyperhomocysteinemic (>12 micromol/L, n=47) and normohomocysteinemic (<12 micromol/L, n=47) according to their serum HCY concentrations.

RESULTS

Folate and vitamin B6, but not vitamin B12, were significantly lower in hyperhomocysteinemic subjects compared with controls. However, DXA, biomechanical testing, and histomorphometry did not reveal significant differences in bone quality between hyperhomocysteinemic subjects and controls.

CONCLUSIONS

The results of the present study do not indicate a significant relationship between circulating HCY concentrations and morphological or biomechanical bone properties in humans with OA of the hip.

Deficiencies of folate and vitamin B12 do not affect fracture healing in mice

PURPOSE

Recently, hyperhomocysteinemia has been shown to be associated with impaired fracture healing in mice. The main causes for hyperhomocysteinemia are deficiencies of folate and vitamin B12. However, there is no information on whether deficiencies of these B vitamins are affecting bone repair, too.

METHODS

We used two groups of mice to investigate the impact of folate and vitamin B12 deficiency on fracture healing: mice of the first group were fed a folate- and vitamin B12-deficient diet (n=14), while mice of the second group received an equicaloric control diet (n=13). Four weeks after stabilizing a closed femur fracture, bone repair was analyzed by histomorphometry and biomechanical testing. In addition, serum concentrations of homocysteine, folate, vitamin B12, the bone formation marker osteocalcin (OC), and the bone resorption marker collagen I C-terminal crosslaps (CTX) were measured.

RESULTS

Serum analyses revealed significantly decreased concentrations of folate and vitamin B12 in animals fed the folate- and vitamin B12-deficient diet when compared to controls. This was associated with a moderate hyperhomocysteinemia in folate- and vitamin B12-deficient mice, while no hyperhomocysteinemia was found in controls. Three-point bending tests showed no significant differences in callus stiffness between bones of folate- and vitamin B12-deficient animals and those of control animals. In accordance, the histomorphometric analysis demonstrated a comparable size and tissue composition of the callus, and also serum markers of bone turnover did not differ significantly between the two groups.

CONCLUSIONS

We conclude that folate and vitamin B12 deficiency does not affect bone repair in mice.

Association of hyperhomocysteinemia with left ventricular dilatation and mass in human heart

BACKGROUND

Hyperhomocysteinemia is a risk factor for ischemic heart disease. Several other mechanisms apply also to dilative types of heart failure of various, non-ischemic etiologies. We hypothesized that hyperhomocysteinemia is associated with left ventricular (LV) dilatation and hypertrophy in dilative cardiomyopathy.

METHODS

Homocysteine was measured in 66 individuals with suspected cardiomyopathy. Cardiac magnetic resonance imaging was used to assess LV volume, mass, and wall stress.

RESULTS

Hyperhomocysteinemia (> 12 micromol/L) was found in 45 patients (68%). LV mass was greater in these patients compared with individuals with normal homocysteine (83+/-27 vs. 67+/-19 g/m(2); p<0.02). Homocysteine was increased in patients with increased brain natriuretic peptide > or = 100 pg/mL (18.3+/-5.9 vs. 14.9+/-5.1 micromol/L; p=0.018). LV mass, LV end-diastolic and end-systolic volume (LVEDV, LVESV) were significantly increased in individuals in the upper quartile compared with the lower quartile (90+/-25 vs. 65+/-18 g/m(2), p=0.021; 114+/-50 vs. 71+/-23 mL/m(2), p=0.042; 76+/-51 vs. 36+/-22 mL/m(2), p=0.045). LV dilatation (LVEDV > or = 90 mL/m(2)) was more common in hyperhomocysteinemia (> 12 micromol/L, p=0.0166). Normalized LV mass was correlated with homocysteine (r=0.346, p=0.065). Homocysteine was not significantly correlated with LVEDV (r=0.229, p=0.065), LV end-diastolic wall stress (r=0.226, p=0.069) and LV ejection fraction.

CONCLUSIONS

Hyperhomocysteinemia appears to be, at least in part, involved in a disproportional LV dilatation, where the ensuing hypertrophy is not sufficient to compensate for the increased wall stress. A potential mechanism is the hyperhomocysteinemia associated increase in oxidative stress that favors muscle fiber slippage.

Hyperhomocysteinemia and the role of B vitamins in cancer

BACKGROUND

Patients suffering from malignancies have increased complications due to corresponding cardiovascular diseases and risk factor for the development of venous thromboembolism. Epidemiological studies have shown that increased homocysteine plasma concentration (hyperhomocysteinemia) is related to a higher risk of coronary heart disease, stroke, peripheral vascular disease and malignancies. Homocysteine (tHcy) is an intermediate sulfur-containing amino acid produced from methionine during processing of dietary proteins. The plasma homocysteine levels are strongly influenced by diet, as well as by genetic factors. Folic acid, vitamins B6 and B12 are dietary components which influence the plasma homocysteine levels the most. Several studies have found that high blood levels of B vitamins are related to the integrity and function of DNA, and, are at least related to lower concentration of homocysteine. Folate depletion has been found to change DNA methylation and DNA synthesis in both animal and human studies. Because of this critical role of folate, most studies including homocysteine have focused on these two actions.

CONCLUSIONS

Hyperhomocysteinemia proves to be the most common condition highly associated with both venous and arterial thrombosis in many cancer patients, while the associated pathophysiology has not been precisely established yet. Therefore, of current interest is the possible role of folate metabolism developing into a cancer initiating hyperhomocysteinemia. This review will discuss this possibility.

Study of molecular targets influencing homocysteine and cholesterol metabolism in growing rats by manipulation of dietary selenium and methionine concentrations

Inconsistent results exist from human and animal studies for Se and methionine (Met) regarding their influence on homocysteine (HCys) and cholesterol (Chol) metabolism. To elucidate these contradictions, sixty-four weanling albino rats were divided into eight groups of 8, and were fed diets containing four different Se levels (15, 50, 150 and 450 microg/kg) either in combination with the recommended Met level of 3 g/kg (C15, C50, C150 and C450) or with an increased Met concentration of 15 g/kg (M15, M50, M150 and M450) for 8 weeks. Plasma HCys was twofold higher in the Se-supplemented C groups than in group C15. Met addition also doubled plasma HCys compared with the respective C groups. In contrast, the expression of the key enzymes of glutathione biosynthesis in the liver was significantly lowered by Se and in particular by Met. Liver Chol concentration was significantly higher in all the Se-supplemented C and M groups than in groups C15 and M15. Plasma Chol was, however, lowered. The uninfluenced expression of sterol-regulatory element-binding protein 2 and of hydroxymethyl-glutaryl-CoA reductase, the increased LDL receptor expression and the reduced expression of the hepatobiliary Chol exporter ATP-binding-cassette-transporter 8 (ABCG8) by Se and/or Met explain these findings. We conclude that the elevation of plasma HCys in rats by Se and Met results from a higher export into plasma. The fact that Se in particular combined with Met increases liver Chol but reduces plasma Chol should be addressed in future investigations focussing on the regulation of ABCG8, which is also selectively involved in the reverse transport of phytosterols in the small intestine.

Rate of T alleles and TT genotype at MTHFR 677C->T locus or C alleles and CC genotype at MTHFR 1298A->C locus among healthy subjects in Turkey: impact on homocysteine and folic acid status and reference intervals

Methylenetetrahydrofolate reductase (MTHFR) is important for folate and homocysteine (Hcy) metabolism. MTHFR 677C->T and 1298A->C MTHFR are two most common mutations which can affect folate and total homocysteine (tHcy) status. This study was designed to determine the rate of MTHFR 677C->T and 1298A->C mutations, and their influence on serum folate, Hcy and vitamin B12 status and the reference intervals in 402 healthy Turkish adults. The rate of MTHFR 677C->T or 1298A->C mutations was 50.7% or 54.7%, respectively. The MTHFR 677C->T mutation-specific reference intervals for serum folate and tHcy were characterized by marked shifts in their upper limits. In homozygote subjects for MTHFR 677C->T serum folate concentration was lower and serum tHcy concentration was higher than those in the wild genotype; all subjects had lower serum folate and 54% of the subjects had higher tHcy concentrations than the cutoff values of <or=10 nmol/L and >or=12 micromol/L, respectively. Serum vitamin B12 status was similar in all genotypes. Serum tHcy concentrations were inversely correlated with serum folate and vitamin B12 concentrations in all genotypes. These data show that the rate of MTHFR 677C->T and 1298A->C mutations is very high in Turks and serum folate and tHcy status are impaired by these mutations.

The association between high plasma homocysteine levels and lower bone mineral density in Slovak women: the impact of vegetarian diet

BACKGROUND

A long-term vegetarian diet is generally poor in vitamin B group. The lack of vitamin B(12) together with vitamin B(6) and folate deficiency is closely related to homocysteine metabolism. Hyperhomocysteinemia was found to be associated with increased bone turnover markers and increased fracture risk. Thus, hyperhomocysteinemia, vitamin B(12) and folate deficiency may be regarded as novel risk factors for micronutrient deficiency-related osteoporosis.

AIM OF THE STUDY

To assess the possible impact of a vegetarian diet on bone mineral density in cohort of Slovak vegetarian women.

METHODS

Fasting serum glucose, albumin, calcium, phosphorous and creatinine as well as bone markers, serum vitamin B(12), folate and plasma levels of total homocysteine were assessed in two nutritional groups (vegetarians vs. nonvegetarians) of apparently healthy women (age range 20-70 years). Bone mineral density of the femoral neck, trochanter, total femur and lumbar spine was measured in all subjects.

RESULTS

Vegetarians had a significantly lower weight (p < 0.05), higher PTH (p < 0.01) and homocysteine (p < 0.001). Vitamin B(12) was significantly higher in nonvegetarians (p < 0.001). No differences were observed in folate levels. Univariate analysis showed significant association between homocysteine and B(12) (p < 0.01), folate (p < 0.001), creatinine (p < 0.001), total proteins (p < 0.049), age (p < 0.001) and vegetarian food intake (p < 0.001). Vegetarians had a significantly lower TrFBMD (p < 0.05) and ToFBMD (p < 0.05). Age and CTx were significant predictors in all sites of measured BMD and PTH. A strong correlation between homocysteine and FNBMD (r = -0.2009, p < 0.002), TrFBMD (r = -0.1810, p < 0.004) and ToFBMD (r = -0.2225, p < 0.001) was found in all subjects.

CONCLUSION

Homocysteine is one of the predictors of bone mineral density, and hyperhomocysteinemia is associated with lower bone mineral density. In healthy adults, homocysteine levels are dependent on age as well as on nutritional habits. Thus, elderly women on a vegetarian diet seem to be at higher risk of osteoporosis development than nonvegetarian women.

Hyperhomocysteinemia in levodopa-treated patients with Parkinson's disease dementia

Dementia is a frequent non-motor feature of Parkinson's disease (PD). Elevated plasma homocysteine (Hcy) levels have been associated with both cognitive impairment and dementia. Increased Hcy levels have been observed in levodopa-treated patients with PD. The objective of our study was to evaluate the association between plasma Hcy levels and dementia in PD. We performed a multicenter cross-sectional study on patients with PD with (PDD) and without (PDnD) dementia and age- and sex-matched healthy controls. We compared Hcy levels in patients with PDD and PDnD and healthy controls, and we performed logistic regression analysis to search for an association between the presence of dementia and increased Hcy levels in PD. Patients with PD (121), PDD (42), and PDnD (79), and age- and sex-matched controls (154) were enrolled. Hcy levels were higher in patients with PD compared to controls (17.5 micromol/L +/- 10.2 vs. 11 +/- 4.1; P < 0.00001). Among patients with PD, Hcy levels were higher in the PDD group compared to the PDnD group (20.7 micromol/L +/- 12.1 vs. 15.8 +/- 8.5; P = 0.002). In a multivariate logistic regression model, higher Hcy levels [Odds ratios comparing the top (>18.9 micromol/L) with the bottom tertile (<12.4 micromol/L): 3.68; 95% CI: 1.14-11.83] were significantly associated with dementia. These data support the association between elevated Hcy levels and the presence of dementia in PD.

Elevated cerebrospinal fluid and plasma homocysteine levels in ALS

BACKGROUND

High cerebrospinal fluid (CSF) and plasma levels of homocysteine (HC) have been reported in certain neurodegenerative disorders, such as Alzheimer's, Parkinson's diseases and, recently, amyotrophic lateral sclerosis (ALS).

OBJECTIVES

To assay the CSF and plasma levels of HC in ALS patients and controls, and to evaluate the relationship between HC levels and clinical variables of the disease.

METHODS

Cerebrospinal fluid from sixty-nine (M/F 1.87) and plasma from sixty-five ALS patients (M/F 1.83) were taken and stored at -80 degrees C until use. Controls (CSF = 55; plasma = 67) were patients admitted to our hospital for neurological disorders with no known relationship to HC changes. CSF and plasma from ALS patients and controls were obtained as a necessary step of the diagnostic workup. HC levels in CSF and plasma were assayed using a high performance liquid chromatograph (HPLC) and a fluorimeter detector.

RESULTS

The median level of total HC in the CSF of ALS patients was 0.46( )microM, significantly higher than that of the controls (0.24 microM, +91.6%, P < 0.001). A similar trend was observed when HC was assayed in plasma (ALS, 12.4 microM vs. controls, 7.26 microM, +70.8%, P < 0.001). The CSF and plasma HC levels showed no relationship with the disease progression, age at onset, and the site of onset.

CONCLUSIONS

Homocysteine is a biochemical marker in ALS, and it might be related to the pathophysiology of the disease.

Influência da adiposidade sobre o risco inflamatório em pacientes com glicemia de jejum alterada

OBJETIVO: Investigar as alterações dos marcadores inflamatórios em obesos com glicemia de jejum alterada. MÉTODOS: Foram avaliados 125 indivíduos adultos tendo sido pesquisados: Índice de Massa Corporal, circunferência da cintura, glicemia de jejum, proteína C reativa ultra-sensível, ácido úrico e homocisteína. Os grupos apresentando glicemia de jejum normal (grupo 1) e glicemia de jejum alterada (grupo 2) foram comparados entre si e em associação aos subgrupos de obesos, sobrepesos e eutróficos. RESULTADOS: O grupo 2 apresentou maiores valores de circunferência da cintura (p<0,05), principalmente quando associados ao excesso de peso. Adicionalmente, o grupo 2 mostrou valores de proteína C reativa e ácido úrico superiores, sendo os dos obesos maiores que os com sobrepeso e os eutróficos, enquanto a homocisteína foi semelhante entre obesos, com sobrepeso e eutróficos. O Índice de Massa Corporal correlacionou-se positivamente com ambos ácido úrico (r=0,39, p<0,01) e proteína C reativa (r=0,37; p<0,01). A circunferência da cintura apresentou correlação apenas com o ácido úrico (r=0,53, p<0,01). Porém, a correlação entre Índice de Massa Corporal e proteína C reativa foi significante no grupo 2 (r=0,66, p<0,01), mas não no grupo 1 (r=0,25, p>0,05). O mesmo resultado foi encontrado em relação à circunferência da cintura e à proteína C reativa, que se correlacionaram significantemente somente na presença de glicemia de jejum alterada (r=0,40, p<0,05). Na regressão logística, a circunferência da cintura foi a variável explicativa (11%, p<0,01) da alteração da glicemia de jejum. CONCLUSÃO: Os estados pró-oxidativo e pró-inflamatório estiveram significantemente associados à glicemia de jejum alterada na presença de adiposidade corporal.

The TT genotype of the C677T polymorphism in the methylentetrahydrofolate reductase as a risk factor in thrombotic microangiopathies: results from a pilot study

In this study, we assessed the potential role of the TT genotype of the gene of the methylenetetrahydrofolate reductase for the manifestation of thrombotic microangiopathies, enrolling 40 affected patients (mean age [+/- standard deviation] 35 +/- 11 years). As a result, the methylenetetrahydrofolate reductase 677TT genotype was more prevalent in patients with thrombotic microangiopathies compared with controls (adjusted odds ratio = 2.58, 95% confidence interval = 1.2-5.7, P = .018), particularly in those suffering from the hemolytic uremic syndrome. A hemolytic more severe clinical course of thrombotic microangiopathies in carriers of the methylenetetrahydrofolate reductase 677TT genotype was not observed. In summary, our findings suggest a significant influence of the methylenetetrahydrofolate reductase genotype on the manifestation of thrombotic microangiopathies. The 677 TT genotype of this polymorphism appears to be a risk factor for manifestation of these rare thrombotic disorders, possibly explained by endothelial activation and increased oxidative stress.

Homocysteine Measurement by an Enzymatic Method and Potential Role of Homocysteine as a Biomarker in Dogs

In humans, homocysteine (Hcy) is employed to monitor renal, cardiovascular, and other diseases and their complications. The aim of the current study was to define the analytical performances of an enzymatic method not yet validated in dogs for measuring homocysteine, and to assess the possible clinical usefulness of Hcy measurement. Using conventional approaches, the analytical performances were investigated by assessing, imprecision, inaccuracy, and interference of hemoglobin, triglycerides, and bilirubin. The possible clinical usefulness of Hcy determination was assessed by comparing the results of healthy dogs ( n = 8) with those of dogs with heart disease ( n = 10), inflammation ( n = 6), gastrointestinal disorders ( n = 7), neoplasia ( n = 8), renal failure ( n = 4), trauma ( n = 7), and other miscellaneous diseases ( n = 6). Preliminary evaluation of this enzymatic method showed it to be precise at Hcy levels close to or higher than the values in dogs with renal or cardiac disorders that had the highest Hcy levels. By contrast, at low Hcy levels, which were recorded basically in control dogs, the method suffers from high imprecision. The sample of choice is serum. The use of icteric samples should be avoided, while hemoglobin and lipids have only a minor effect on Hcy measurement. In conclusion, the enzymatic method employed in the current study provides useful information in dogs and could be used to monitor cardiac and renal disorders, in which Hcy concentrations are elevated.

Folic acid deficiency increases delayed neuronal death, DNA damage, platelet endothelial cell adhesion molecule-1 immunoreactivity, and gliosis in the hippocampus after transient cerebral ischemia

Folic acid deficiency increases stroke risk. In the present study, we examined whether folic acid deficiency enhances neuronal damage and gliosis via oxidative stress in the gerbil hippocampus after transient forebrain ischemia. Animals were exposed to a folic acid-deficient diet (FAD) for 3 months and then subjected to occlusion of both common carotid arteries for 5 min. Exposure to an FAD increased plasma homocysteine levels by five- to eightfold compared with those of animals fed with a control diet (CD). In CD-treated animals, most neurons were dead in the hippocampal CA1 region 4 days after ischemia/reperfusion, whereas, in FAD-treated animals, this occurred 3 days after ischemia/reperfusion. Immunostaining for 8-hydroxy-2'-deoxyguanosine (8-OHdG) was performed to examine DNA damage in CA1 neurons in both groups after ischemia, and it was found that 8-OHdG immunoreactivity in both FAD and CD groups peaked at 12 hr after reperfusion, although the immunoreactivity in the FAD group was much greater than that in the CD group. Platelet endothelial cell adhesion molecule-1 (PECAM-1; a final mediator of neutrophil transendothelial migration) immunoreactivity in both groups increased with time after ischemia/reperfusion: Its immunoreactivity in the FAD group was much higher than that in the CD group 3 days after ischemia/reperfusion. In addition, reactive gliosis in the ischemic CA1 region increased with time after ischemia in both groups, but astrocytosis and microgliosis in the FAD group were more severe than in the CD group at all times after ischemia. Our results suggest that folic acid deficiency enhances neuronal damage induced by ischemia.

Total homocysteine, B-vitamins and genetic polymorphisms in patients with classical phenylketonuria

Hyperhomocysteinemia has occasionally been reported in patients with phenylketonuria (PKU) and B-vitamin deficiency. In our study total homocysteine (tHcy) and B-vitamins were measured in treated PKU patients and healthy controls. In the patients, dietary parameters and genetic polymorphisms affecting the Hcy pathway were investigated to identify parameters modulating tHcy. A case control study including 37 PKU patients and 63 healthy controls was conducted. t-Tests for independent samples were used to test between groups. Multiple regressions with tHcy as dependent variable were calculated. Hardy-Weinberg expectations were tested against the observed distribution of genotypes applying the Chi-square goodness-of-fit method. THcy concentrations were not significantly different (p=0.059) while folate and cobalamin (Cbl) concentrations were significantly higher in PKU patients compared to controls. However, 29.7% of patients had tHcy concentrations >97th centile. THcy did not vary with age nor correlate with folate and Cbl concentrations probably due to high saturatory levels. The presence of genetic polymorphisms had no impact on tHcy. In conclusion, in PKU patients treated with amino acid mixtures enriched with B-vitamins, tHcy is not significantly higher than in healthy controls, but tHcy concentrations exceed the 97th centile in about one third of patients. Even higher B-vitamin saturation may be required to further decrease tHcy concentrations and factors generally influencing tHcy such as betaine are to be investigated in PKU patients in the future.

The effect of B-vitamins on biochemical bone turnover markers and bone mineral density in osteoporotic patients: a 1-year double blind placebo controlled trial

BACKGROUND

Hyperhomocysteinemia is a new risk factor for osteoporosis. This study analyzed the effect of a homocysteine (HCY)-lowering treatment in osteoporotic individuals.

METHODS

Osteoporotic subjects (n=47, 55-82 years) were treated with either a combination of 2.5 mg folate, 0.5 mg vitamin B(12) and 25 mg vitamin B(6) or placebo. Bone mineral density (BMD) at lumbar spine and hip was measured at baseline and after 1 year. Urinary desoxypyridinoline cross-links (DPD) and plasma levels of tartrate resistant acid phosphatase (TRAP), C-terminal cross-links of collagen I (CTx), pro-collagen type I N-terminal peptide (PINP) and osteocalcin (OC) were measured after 0, 4, 8 and 12 months.

RESULTS

B-vitamin supplementation significantly reduced HCY (0 vs. 12 months: 13.6+/-4.8 vs. 8.9+/-2.4 micromol/L). Placebo treatment had no effect on HCY (0 vs. 12 months: 12.0+/-3.4 vs. 12.7+/-3.9 micromol/L). BMD, TRAP, CTx, OC and PINP did not change throughout the study in both groups. Vitamin treatment decreased urinary DPD by -13% (p<0.01) after 8 and 12 months. In a sub-group analysis of hyperhomocysteinemic subjects (HCY>15 mumol/L, n=8), B-vitamin treatment tended to increase BMD at the lumbar spine, with a t-score from -2.7 to -1.7, and to decrease OC and PINP by approximately 50%.

CONCLUSIONS

B-vitamin supplementation had no consistent effects on bone turnover or BMD. However, the situation may be different in patients with hyperhomocysteinemia.

The role of hyperhomocysteinemia as well as folate, vitamin B(6) and B(12) deficiencies in osteoporosis: a systematic review

Hyperhomocysteinemia (HHCY) has been suggested as a new risk factor for osteoporosis. Recent epidemiological, clinical and experimental studies provide a growing body of data, which is reviewed in this article. Epidemiological and (randomized) clinical trials suggest that HHCY increases fracture risk, but has minor effects on bone mineral density. Measurement of biochemical bone turnover markers indicates a shift of bone metabolism towards bone resorption. Animal studies confirm these observations showing a reduced bone quality and stimulation of bone resorption in hyperhomocysteinemic animals. Homocysteine (HCY) has been found to accumulate in bone by collagen binding. Cell culture studies demonstrate that high HCY levels stimulate osteoclasts but not osteoblasts, indicating again a shift of bone metabolism towards bone resorption. Regarding B-vitamins, only a few in vivo studies with equivocal results have been published. However, two large cell culture studies confirm the results obtained with exogenous HCY administration. In addition, HHCY seems to have adverse affects on extracellular bone matrix by disturbing collagen crosslinking. In conclusion, existing data suggest that HHCY (and possibly B-vitamin deficiencies) adversely affects bone quality by a stimulation of bone resorption and disturbance of collagen crosslinking.

Factors associated with serum total homocysteine level in type 2 diabetes

OBJECTIVES

The aim of this study was to investigate the determinants of serum total homocysteine level (tHcy) in patients with type 2 diabetes mellitus (DM) according to sex.

METHODS

A total of 1,276 Japanese, diabetics (n = 280) with a control group of non-diabetics (n = 996), were enrolled into the study from 2003 to 2005. This cross-sectional study was conducted for all the subjects, using personal data regarding clinical characteristics and lifestyle. Multiple regression analysis was performed to analyze the association of tHcy with selected factors.

RESULTS

In diabetic subjects, estimated glomerular filtration rate (eGFR) and serum creatinine levels (Cre), even those within the normal range, were strongly associated with tHcy after adjustment in both sexes; the standardized partial regression coefficient of eGFR for tHcy was -0.251, (p = 0.001) in diabetic men and -0.523, (p < 0.001) in diabetic women. Furthermore, the eGFR of the diabetics, except patients with nephropathy, also had significant association with tHcy in both sexes. Fasting plasma glucose levels and serum triglyceride levels were strongly associated with tHcy in diabetic men only. HbA1c was also associated with tHcy in diabetic men only, though not as significantly. Age and presence of hypertension were significantly associated with tHcy in women.

CONCLUSIONS

This study suggests that there are some differences in the factors associated with tHcy between diabetics and non-diabetics, and between the sexes. There is, therefore, circumstantial evidence that elevated tHcy should be evaluated clinically. Because tHcy was strongly associated with eGFR and Cre, even within the normal ranges, tHcy may have important implications regarding the microangiopathy of the kidney and atherosclerosis.

Plasma homocysteine concentrations and serum lipid profile as atherosclerotic risk factors in subclinical hypothyroidism

BACKGROUND AND OBJECTIVES

Because subclinical thyroid dysfunction may be a risk factor for cardiovascular disease, we evaluated the atherosclerosis tendency in subclinical hypothyroid (SCH) patients.

PATIENTS AND METHODS

Fifty-three subclinical hypothyroid patients (serum thyrotropin [TSH] concentrations >4.12 mU/L) were compared with a control group of 50 euthyroid subjects whose age, sex and body mass indices were similar to the patient group. We tested whether serum TSH concentrations were correlated with plasma total homocysteine concentration (tHcy), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC) and triglycerides (TG).

RESULTS

There was a significant statistical difference between the patient and control groups for normal free T4 (1.02+/-0.17 vs. 0.86+/-0.13, P<.001), TSH (1.64+/-1.02 vs. 6.62+/-2.61, P<.001), TC (185+/-39 vs. 206 +/- 42, P=.01), TG (103+/-54 vs. 132+/-85, P=.04), LDL-C (114+/-33 vs. 127+/-36, P=.04), and TC/HDL-C (3.81+/-106 vs. 4.19+/-1.02, P=.04), respectively. No statistically significant difference was found between the two groups for HDL-C, VLDLC, LDL-C/HDL-C, and tHcy. Serum TSH was significantly correlated with plasma tHcy (r=0.55; P=.001), TC (r=0.52; P=.001), LDL-C (r=0.49; P=.001), TC/HDL-C (r=0.38; P=.002) and LDL-C/HDL-C (r=0.36; P=.004) across all participants.

CONCLUSION

Our study suggests that the atherogenicity of SCH is not mediated by hyperhomocysteinemia. Associated hyperlipidemia may explain the observed increased risk of coronary artery disease in patients with SCH.

Modern society and prospects of low vitamin B12 intake

BACKGROUND

Vitamin B(12) deficiency can occur in individuals with dietary patterns that exclude animal foods and patients who are unable to absorb vitamin B(12 )in food.

MATERIAL AND METHOD

Our clinic serves a high-income population living in Southern Israel. We hypothesize that a tendency to decrease of level of vitamin B(12) in our population is caused by a premeditated decrease in consumption of animal products. We analyzed 512 medical histories of patients undergoing blood tests for vitamin B(12) level for various reasons.

RESULT

The level of vitamin B(12) in 192 patients (37.5%) was less than 250 pg/ml.

CONCLUSION

As a result of media information disseminating the relationship between meat, cholesterol and cardiovascular diseases, consumption of meat, particularly beef, has decreased. Changes in life style among segments of the population with high socioeconomic level, on one hand, and the existence of poverty, on the other, are two main factors in the decreasing consumption of animal products. This causes a decrease in the level of vitamin B(12) in the general population, and as a consequence, this will increase pathology due to vitamin B(12) deficiency. In lieu of these possible developments and in order to prevent serious health problems, vitamin B(12) fortification should be seriously considered and discussed.

Prophylaxe der Präeklampsie

The pathophysiology of preeclampsia is still unknown. Low-dose aspirin showed a reduction of the preeclampsia rate in a high-risk situation.There is a lack of prospective randomized studies to prove the benefit of heparin treatment in patients with hereditary thrombophilia. Different prophylactic therapies did not show any benefit in the prevention of preeclampsia in clinical studies.

Stimulation of osteoclast activity by low B-vitamin concentrations

BACKGROUND

Homocysteine (HCY) has recently been linked to fragility fractures. Moreover, HCY activates osteoclasts (OC). Elevated HCY concentrations are mainly caused by folate, vitamin B12 (B12) and B6 (B6) deficiencies. We hypothesized that folate, B12 and B6 deficiencies stimulate OC activity.

MATERIALS AND METHODS

OC were cultured from peripheral blood mononuclear cells (10 healthy male donors, 34+/-5 years) for 20 days. Culture medium was conditioned with decreasing concentrations of folate, B12 and B6 (in combination or variation of only one vitamin) starting at physiologic concentrations. Moreover, we tested increasing concentrations of HCY. OC activity was measured by dentine resorption activity (DRA), tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CK) activity.

RESULTS

The combined reduction of folate, B12 and B6 stimulated DRA up to 211% (p<0.001). This observation was confirmed by TRAP (maximum increase 24%, p<0.001) and CK (maximum increase 24%, p<0.001). Reduction of only one vitamin stimulated DRA up to 250% (folate: maximum increase 248%, p<0.018; B12: maximum increase 252%, p<0.001, B6: maximum increase 247%, p<0.001). However, only for folate this effect could be confirmed by TRAP (maximum increase 33%, p<0.001). HCY stimulated DRA up to 395% (p<0.001). TRAP (maximum increase 49%, p<0.001) and CK analyses confirmed this observation (maximum increase 50%, p<0.001).

CONCLUSION

Our results demonstrate a strong stimulatory effect of low concentrations of folate, B12 and B6 on OC activity, suggesting a mechanistic role of low B-vitamin concentrations for bone degradation. Consequently, OC stimulation by low folate, B12 and B6 concentrations could be an important adverse factor for bone health.

Concentraciones elevadas de homocisteína en el síndrome de ovario poliquístico

BACKGROUND AND OBJECTIVE

Women with polycystic ovary syndrome (PCOS) exhibit frequently risk factors that predispose to cardiovascular disease. Hyperhomocysteinemia is an independent risk factor for this disease. The aim of this study was to know whether young women with PCOS have increased homocysteine levels. We also analyzed their possible relation with folate and vitamin B12 levels.

PATIENTS AND METHOD

Thirty nine patients with PCOS were studied; (age: mean [standard deviation] 28.9 [5.8] years), and 39 healthy women similar in age. We evaluated in all of them: smoking, menstrual cycles, hirsutism, body mass index, metabolic syndrome and levels of homocysteine, lipids, glucose, creatinine, folate, vitamin B12, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and androstendione.

RESULTS

Menstrual cycles, hirsutism, androstendione, LH levels and LH/FSH were higher, as we expected, in patients with PCOS. Moreover, patients had increased homocysteine (9.1 [2.1] vs 6.4 [1.8] micromol/L; p < 0.001) and glucose levels (99 [13] vs 88 [10] mg/dl; p < 0.001), a higher frequency of abnormal fasting glycemia (> 110 mg/dl) (23% vs 2.5%; p =.01) and lower folate levels (7.6 [3.7] vs 10.2 [3.6] ng/ml; p = 0.02). A multiple linear regression showed a negative association between homocysteine and folate levels (r2 = 0.05; p =.02).

CONCLUSIONS

Homocysteinemia is increased in women with PCOS, and it is negatively associated with folate levels.

Accumulation of homocysteine by decreasing concentrations of folate, vitamin B12 and B6 does not influence the activity of human osteoblasts in vitro

BACKGROUND

Homocysteine (HCY) has recently been linked to fragility fractures. Elevated circulating HCY is mainly caused by folate, vitamin B12 and B6 deficiencies. However, little is known about the effect of these vitamins on the activity of osteoblasts. We hypothesized that decreasing concentrations of folate, vitamin B12 and B6 decrease osteoblasts activity by accumulation of HCY.

METHODS

Osteoblasts obtained from trabecular human bone specimens of 8 donors were cultured with decreasing concentrations of folate, vitamin B12 and B6. Vitamin concentrations were modified in combination or one vitamin only (8 repetitions x 8 donors, n=64). After 14 days alkaline phosphatase (AP) activity, pro-collagen type I N-terminal peptide (PINP) and osteocalcin secretion in the supernatant was measured. After 20 days, the formation of mineralized matrix was analyzed.

RESULTS

Decreasing B-vitamin concentrations induced a significant accumulation of HCY in the supernatant reaching up to 160%. The increase in HCY was not accompanied by changes of AP, osteocalcin and PINP. Moreover, mineralized matrix formation was not affected.

CONCLUSION

Accumulation of HCY by decreasing concentrations of folate, vitamin B12 and B6 does not affect the activity of human osteoblasts. Consequently, other mechanisms have to be responsible for the reduced bone quality in hyperhomocysteinemic subjects.

Specific reactions of S-nitrosothiols with cysteine hydrolases: A comparative study between dimethylargininase-1 and CTP synthetase

S-Transnitrosation is an important bioregulatory process whereby NO(+) equivalents are transferred between S-nitrosothiols and Cys of target proteins. This reaction proceeds through a common intermediate R-S-N(O(-))-S-R' and it has been proposed that products different from S-nitrosothiols may be formed in protein cavities. Recently, we have reported on the formation of such a product, an N-thiosulfoximide, at the active site of the Cys hydrolase dimethylargininase-1 (DDAH-1) upon reaction with S-nitroso-l-homocysteine (HcyNO). Here we have addressed the question of whether this novel product can also be formed with the endogenously occurring S-nitrosothiols S-nitroso-l-cysteine (CysNO) and S-nitrosoglutathione (GSNO). Further, to explore the reason responsible for the unique formation of an N-thiosulfoximide in DDAH-1 we have expanded these studies to cytidine triphosphate synthetase (CTPS), which shows a similar active site architecture. ESI-MS and activity measurements showed that the bulky GSNO does not react with both enzymes. In contrast, S-nitrosylation of the active site Cys occurred in DDAH-1 with CysNO and in CTPS with CysNO and HcyNO. Although kinetic analysis indicated that these compounds act as specific irreversible inhibitors, no N-thiosulfoximide was formed. The reasons likely responsible for the absence of the N-thiosulfoximide formation are discussed using molecular models of DDAH-1 and CTPS. In tissue extracts DDAH was inhibited only by HcyNO, with an IC(50) value similar to that of the isolated protein. Biological implications of these studies for the function of both enzymes are discussed.

Experimental hyperhomocysteinemia reduces bone quality in rats

BACKGROUND

Recently, hyperhomocysteinemia (HHCY) has been suggested as a new risk factor for osteoporosis. This study investigated if HHCY is a causal osteoporotic factor in vivo.

METHODS

We used 3 groups of rats: a control group (n = 20), a moderate HHCY group (induced by a 2.4% methionine-enriched diet, n = 10), and an intermediate HHCY group (induced by a 2% homocystine-enriched diet, n = 10). We measured bone fragility [maximum force of an axial compression test (F(max))], bone area as percentage of total area (BAr/TAr, histomorphometry), and biochemical bone turnover markers [osteocalcin (OC) and collagen I C-terminal crosslaps (CTx)].

RESULTS

Compared with controls, 3 months of moderate or intermediate HHCY increased mean (SD) bone fragility at the femoral neck by 18% (6%) in methionine-fed (P = 0.001) and 36% (13%) in homocystine-fed rats (P <0.001). Mean (SD) BAr/TAr at the distal femur in methionine and homocystine groups was decreased by 45% (21%; P = 0.001) and 93% (9%; P = 0.001), respectively. At the femoral neck, BAr/TAr was decreased by 19% (11%; P <0.001) and 55% (19%; P <0.001). At the lumbar spine, the reduction of BAr/TAr was 17% (23%; P = 0.099) and 44% (19%; P <0.001). Plasma OC (bone formation marker) was decreased by 23% (20%; P = 0.006) and 34% (21%; P <0.001). Plasma CTx (bone resorption marker) did not differ between groups.

CONCLUSION

Bone quality is consistently decreased in the presence of increased circulating homocysteine. The results provide evidence that HHCY is a causal osteoporotic factor.