Relationship between homocysteine and thrombotic disease

Review of the Protective Mechanism of Curcumin on Cardiovascular Disease

Cardiovascular diseases (CVDs) are the most common cause of death worldwide and has been the focus of research in the medical community. Curcumin is a polyphenolic compound extracted from the root of turmeric. Curcumin has been shown to have a variety of pharmacological properties over the past decades. Curcumin can significantly protect cardiomyocyte injury after ischemia and hypoxia, inhibit myocardial hypertrophy and fibrosis, improve ventricular remodeling, reduce drug-induced myocardial injury, improve diabetic cardiomyopathy(DCM), alleviate vascular endothelial dysfunction, inhibit foam cell formation, and reduce vascular smooth muscle cells(VSMCs) proliferation. Clinical studies have shown that curcumin has a protective effect on blood vessels. Toxicological studies have shown that curcumin is safe. But high doses of curcumin also have some side effects, such as liver damage and defects in embryonic heart development. This article reviews the mechanism of curcumin intervention on CVDs in recent years, in order to provide reference for the development of new drugs in the future.

The Controversial Role of Homocysteine in Neurology: From Labs to Clinical Practice

Homocysteine (Hcy) is a sulfur-containing amino acid that is generated during methionine metabolism. Physiologic Hcy levels are determined primarily by dietary intake and vitamin status. Elevated plasma levels of Hcy can be caused by deficiency of either vitamin B12 or folate. Hyperhomocysteinemia (HHcy) can be responsible of different systemic and neurological disease. Actually, HHcy has been considered as a risk factor for systemic atherosclerosis and cardiovascular disease (CVD) and HHcy has been reported in many neurologic disorders including cognitive impairment and stroke, independent of long-recognized factors such as hyperlipidemia, hypertension, diabetes mellitus, and smoking. HHcy is typically defined as levels >15 micromol/L. Treatment of hyperhomocysteinemia with folic acid and B vitamins seems to be effective in the prevention of the development of atherosclerosis, CVD, and strokes. However, data from literature show controversial results regarding the significance of homocysteine as a risk factor for CVD and stroke and whether patients should be routinely screened for homocysteine. HHcy-induced oxidative stress, endothelial dysfunction, inflammation, smooth muscle cell proliferation, and endoplasmic reticulum (ER) stress have been considered to play an important role in the pathogenesis of several diseases including atherosclerosis and stroke. The aim of our research is to review the possible role of HHcy in neurodegenerative disease and stroke and to understand its pathogenesis.

Hyperhomocysteinemia and neurologic disorders: a review

Homocysteine (Hcy) is a sulfur-containing amino acid that is generated during methionine metabolism. It has a physiologic role in DNA metabolism via methylation, a process governed by the presentation of folate, and vitamins B6 and B12. Physiologic Hcy levels are determined primarily by dietary intake and vitamin status. Elevated plasma levels of Hcy (eHcy) can be caused by deficiency of either vitamin B12 or folate, or a combination thereof. Certain genetic factors also cause eHcy, such as C667T substitution of the gene encoding methylenetetrahydrofolate reductase. eHcy has been observed in several medical conditions, such as cardiovascular disorders, atherosclerosis, myocardial infarction, stroke, minimal cognitive impairment, dementia, Parkinson's disease, multiple sclerosis, epilepsy, and eclampsia. There is evidence from laboratory and clinical studies that Hcy, and especially eHcy, exerts direct toxic effects on both the vascular and nervous systems. This article provides a review of the current literature on the possible roles of eHcy relevant to various neurologic disorders.

Axillary artery thrombosis in a neonate in utero: a case report

We describe a neonate of 38-week and 6-day gestation born by lower uterine cesarean section for breech presentation, where it was evident on delivery that there was significant edema of the right arm from the deltoid to the distal tips of the fingers. Doppler flow ultrasound revealed extensive arterial thromboembolus. Intravenous heparin was prescribed for three days at a dose of 27.5 U/kg/h, targeting an activated partial thromboplastin time (APTT) of 60–75 seconds, followed by a course of subcutaneous enoxaparin at a dose of 1.8 mg/kg and then 2 mg/kg twice daily, titrated to a factor Xa level of 0.5–1.0 U/mL for another three days. Significant clinical improvement occurred and the child was eventually, discharged on subcutaneous enoxaparin. Magnetic resonance imaging showed multiple intracranial abnormalities. At five months increased upper limb tone, brisk reflexes, and small head circumference were noted. At one year, increased tone and increased paucity of movement on the right side persisted, and some speech delay and visual inattention were noted. Recent follow-up at 16.5 months of age demonstrated a right sided hemiplegia with increased tone and brisk reflexes. We describe the case in detail and review current knowledge regarding the management of arterial thrombosis in the neonate.

Temporomandibular joint ankylosis: is hypercoagulable state of blood a predisposing factor?

Temporomandibular joint (TMJ) ankylosis is a significant problem in Asian countries and the most common etiology is trauma to the mandibular condyle. Other less common etiologies are infection, forceps delivery trauma and rheumatoid arthritis. Many hypotheses are given to explain the pathogenesis. All the proposed hypotheses revolve around trauma to the joint and subsequent healing causing ankylosis. This is however true for only few patients, most of the others do not progress to ankylosis after trauma to TMJ irrespective of seeking treatment or not. In this paper, we try to answer the question that why only a minor subset of condylar injuries progress to ankylosis and why others do not? The hypothesis follows a report of 4 cases that had bilateral TMJ ankylosis with extrahepatic portal venous obstruction (EHPVO) secondary to protein C deficiency. It is postulated that hypercoagulability/reduced fibrinolytic activity in these as well as non-EHPVO patients with TMJ ankylosis cases may have predisposed them to the development of joint ankylosis. The possible mechanism is explained and correlated with other causes of TMJ ankylosis and known facts of protein C deficiency/activated protein C resistance.

Serum homocysteine and folate concentrations among a US cohort of adolescents before and after folic acid fortification

OBJECTIVE

We assessed serum homocysteine (tHcy) and folate concentrations among US adolescents before and after fortification of cereal-grain products with folic acid, and associations with demographic, behavioural and physiological factors.

DESIGN

Observational study conducted among participants of a randomized trial.

SETTING

The Child and Adolescent Trial for Cardiovascular Health (CATCH) study.

SUBJECTS

Adolescents (n 2445) in grades 8 (pre-fortification, mean age 14 years) and 12 (post-fortification, mean age 18 years).

RESULTS

Average serum concentrations of tHcy, folate and vitamin B6 increased by 17 %, 16 % and 14 %, respectively, while serum concentrations of vitamin B12 decreased by 11 % post-fortification. Folic acid fortification provided, on average, an additional intake of 118 μg folate/d. Male sex (P < 0.0001) and white race (P = 0.0008) were associated with significantly greater increases in tHcy concentration, while increases in BMI (P = 0.006) and serum folate concentration (P < 0.0001) were associated with significant decreases in tHcy concentration. Female sex (P < 0.0001), non-smoking (P < 0.0001), use of multivitamins (P < 0.0001) and higher dietary intake of folate (P = 0.001) were associated with significantly greater increases in serum folate concentrations. From grade 8 to grade 12, the upward age trend in serum tHcy concentration was uninterrupted in its course (P > 0.50); whereas serum folic acid concentration showed a downward trend that incurred a discrete jump upward (17 % higher; P < 0.0001) with fortification. These trends differed significantly for males v. females (P < 0.001 for interaction).

CONCLUSIONS

Fortification had a significant impact on improving folate status but not serum tHcy concentrations among US adolescents.

Hyperhomocysteinemia and cardiovascular disease: The nutritional perspectives

Several members of the vitamin B-complex family are known to participate in the normal metabolism of homocysteine (Hcy). Leaving aside the genetic determinants of hyperhomocysteinemia (HHC), the deficiencies of these vitamins can also result in HHC. The situation of sustained and long standing HHC is likely to be prevalent in population groups with low/average socio-economic status, geriatric population and alcohol abusers. If not corrected by supplementation, these population groups certainly are more vulnerable to develop atherosclerosis (AS) and subsequently, cardiovascular disease (CVD). Hyperhomocysteinemia per se and/or HHC-induced oxidative stress result(s) in chronic chemical endothelial injury/dysfunction, smooth muscle proliferation, prothrombotic state and oxidation of low density lipoproteins (LDL) leading to diverse cardiovascular complications. In the first decade of the new millennium, major research efforts would be directed towards understanding the basic mechanism of HHC-induced oxidative stress and the pathophysiology of HHC-induced CVD, culminating in the evolution of hitherto unknown therapeutic strategies such as nutriceuticals and oxidant-antidotes.

Pheochromocytoma presenting with arterial and intracardiac thrombus in a 47-year-old woman: a case report

Introduction

Pheochromocytoma is a rare cause of hypertension but it could have severe consequences if not recognized and treated appropriately. The association of pheochromocytoma and thrombosis is even rarer but significantly increases management complexity, morbidity and mortality. To the best of our knowledge, this is the first report of a patient with pheochromocytoma presenting with left axillary arterial and intracardiac thrombus.

Case presentation

A 47-year-old Caucasian woman with a past medical history of hypertension presented for medical attention with left arm numbness. Doppler ultrasound showed an obstructing thrombus in her left axillary artery. She had symptom resolution after stent placement in her left axillary artery. A subsequent echocardiogram demonstrated a large intracardiac mass and abdominal computed tomography revealed a 7 cm mass between her spleen and left kidney. Labile blood pressure was noted during admission and she had very high levels of plasma and 24-hour urine catecholamines and metanephrines tests. A (123)I- metaiodobenzylguanidine scan showed intense uptake in the left abdominal mass. After adequate alpha blockage with phenoxybenzamine, laparoscopic tumor resection was performed without complications. She had normal metanephrines and complete symptom resolution afterwards. The intracardiac mass also disappeared with anticoagulation. All other endocrine laboratory abnormalities returned to normal after surgery.

Conclusion

Arterial and ventricular thrombosis occurring in patients with pheochromocytoma is rare. A multi-disciplinary approach is necessary in caring for this type of patient. Catecholamines likely contributed to the development of thrombosis in our patient. Early recognition of pheochromocytoma is the key to improving outcome.

Myocardial infarction and venous thrombosis in a 42-year old woman with heterozygous methylenetetrahydrofolate reductase (MTHRF) gene mutation, hyperhomocysteinemia, and protein C deficiency

OBJECTIVE

Hyperhomocysteinemia and protein C deficiency have synergistic effect on the onset of thrombotic disease.

METHODS

We report a 42-year old woman with myocardial infarction and venous thrombosis in whom recognition of heterozygous MTHRF gene mutation, hyperhomocysteinemia, and protein C deficiency.

RESULTS

The patient was treated successfully with coronary artery bypass graft surgery and systemic anticoagulation.

CONCLUSIONS

Our report emphasize that a combined hyperhomocysteinemia, and protein C deficiency may be a high risk factor for arterial and venous thromboembolic events in young adults. These patients might be candidates for indefinite anticoagulation.

[Association of tow thrombotic risk factors: factor V Leiden and hyperhomocysteinemia. A case report]

The identification of constitutional and/or acquired risk factor is of major importance in the treatment of thromboembolic disease in young people; it contributes to evaluate the risk of recurrence and to define the period of oral prophylactic anticoagulant treatment. Several congenital or acquired abnormalities of haemostasis are actually defined. In this paper, we report the case of a 34-year-old man who developed a deep venous thrombosis, five months before the diagnosis of megaloblastic anemia, probably due to pernicious anemia. The thrombosis was partially explained by the acquired hyperhomocysteinemia induced by vitamin B12 deficiency. Moreover, activated protein C resistance due to factor V Leiden, was revealed in our patient. This latter improved under anticoagulant treatment combined with vitamin B12. Combination in one individual, of different risk factors predisposing to inherited and/or acquired thrombophilia, results in increased risk for thrombo-embolic disease, suggesting synergic interaction between these factors.

Cancer: a single disease with a multitude of manifestions?

The relationships of critical nutrients such as plant phenolics, vitamins, minerals and lipids are considered with respect to the incidence of a variety of cancers, and analyzed in terms of how these nutrient deficiencies alter immune function, DNA integrity and cell proliferation. With a significant correlation found between cancer and these nutrient deficiencies, the hypothesis is presented here that nutrition could provide a unifying perception of cancer and recast it as a single disease. This further suggests that a coordinated administration of specific, critical nutrients to cancer patients could lead to the reversal of the disease. It is also proposed that the concurrent presence of a variety of nutritional deficiencies in cancer patients requires a multilevel, systemic approach to this disease as opposed to the single active therapeutic agent approach that is the cornerstone of contemporary research and pharmacology.

Methylenetetrahydrofolate reductase and angiotensin converting enzyme gene polymorphisms in two genetically and diagnostically distinct cohort of Alzheimer patients

The role of methylenetetrahydrofolate reductase (MTHFR) and angiotensin converting enzyme (ACE) gene polymorphisms as risk factors for the occurrence of Alzheimer's disease (AD) is still controversial. In this study, we investigated the common MTHFR C677-->T and ACE insertion/deletion (I/D) gene polymorphisms as risk factors for AD in two genetically and diagnostically distinct cohort of Alzheimer's patients. We analyzed a neuropathologically confirmed American cohort of 124 AD patients and 97 elderly controls, and a clinically diagnosed Italian cohort of 126 probable AD cases, 106 elderly controls, and a community-based sample of 1232 subjects aged under 65 years. No difference was found in polymorphism distribution between cases and controls in both study cohorts. We also tested a possible association between the polymorphisms investigated. No interaction was found between the MTHFR and ACE alleles. Moreover, no association was found for the ACE and MTHFR polymorphisms with age at onset, disease duration and MMSE score at observation. Thus, in our study, MTHFR C677-->T and ACE I/D polymorphisms do not appear to confer an added risk for AD.

Primary prevention: phytoprevention and chemoprevention of colorectal cancer

Considering the various stages of carcinogenesis and the numerous tumor types and available chemoprevention agents, knowledge of the etiology and the type of cancer to be treated, or possibly prevented, and understanding of the mechanisms by which agents exert their chemoprevention benefits may provide for improved strategy in designing therapeutic regimens. Because cancer usually develops over a 10- to 20-year period, it may be necessary for some agents to be provided before or early in the initiation steps of carcinogenesis to have beneficial effects. On the other hand, some agents may be more suitable for CRC prevention if provided at a later stage of carcinogenesis. Gene array, genomics, and proteomics are useful tools in advancing our understanding of the molecular events involved in carcinogenesis and in identifying markers of risk and surrogate end-points for colorectal cancer progression. These techniques may also serve for screening, identifying, and providing treatment targets for high-risk patients populations. Treatment could be developed depending on a patient's individual needs and genomic tumor profile. Clinical markers and surrogate end-points should be considered, together with molecular measurements, to more accurately assess risk. NSAIDs and COXIBs are clinically recognized as chemoprevention agents, and clinical trials evaluating their efficacy are ongoing. Treatment protocols, including dose and timing, remain to be determined, however. DFMO may best be used in combination with other chemoprevention agents. Dietary fiber and calcium supplements, as part of an overall low-fat diet, may decrease CRC risk. Long-term compliance with this regimen may be necessary to effect a beneficial outcome. Folate holds promise but needs further investigation, especially because its beneficial effects may depend on cancer type. Phytochemicals have been identified as strong candidates for use as agents to prevent colorectal cancer in cell culture and in rodent models of carcinogenesis. Their potential as chemoprevention agents must be demonstrated in clinical trials. In vitro and animal studies indicated that combination therapy may be a promising strategy over the monotherapy approach; clinical trials addressing the safety and efficacy of some combinations (DFMO/sulindac, fiber/calcium) are underway. The gastrointestinal tract and other organs are constantly exposed to a mixture of potentially toxic compounds and molecules considered favorable to health. Homeostasis between stress-mediated by toxic compounds and defensive mechanisms, is key for the maintenance of health and the prevention of disease. Whereas aggressive pharmacologic treatment may be necessary for patients at high risk for cancer, dietary supplements may be useful for populations at normal risk. The message for cancer prevention in the general population may well remain: keep a balanced healthy diet, eating a variety from all food groups, as part of a healthy lifestyle that includes moderate exercise.

The 677C --> T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in epileptic patients affected by systemic lupus erythematosus

Neuropsychiatric involvement in systemic lupus erythematosus (NPSLE) is considered as one of the major manifestations of the disease. Epilepsy has been documented in about 10% of patients with systemic lupus erythematosus (SLE). It is well known that vascular damage in SLE occurs because of multiple mechanisms including hypercoagulation. It has been recently reported that in SLE patients raised levels of homocysteine are associated with arterial thrombosis. Hyperhomocysteinaemia is a condition due to both genetic and non-genetic factors. The most common genetic defect in homocysteine metabolism is a decreased activity of a common 5,10-methylenetetrahydrofolate reductase (MTHFR) variant (677C -->T, a thermolabile form). In this paper we describe the epileptic manifestations in six out of 55 SLE patients. Seizures were the SLE onset symptom for three patients, appeared during the active disease in two cases, and occurred during a period of clinical remission in one patient. In all cases we documented the association of epilepsy with the MTHFR mutation: the homozygosity form was present in one case (16.7%), and heterozygosity in five cases (83.3%). Nevertheless, levels of homocysteine in plasma were in the normal range. Moreover, we found a decrease in the level of S protein values in one case, a high titre positivity of anticardiolipin antibodies (aCL) (IgG and IgM) in three patients and low titre positivity (IgG) in one patient, and lupus anticoagulant (LAC) positivity in four cases. In conclusion, we believe that the abnormalities of coagulation present in our patients could be related to epileptogenesis or to an alteration of the seizure threshold.

Hyperhomocysteinemia and venous thromboembolism: a risk factor more prevalent in the elderly and in idiopathic cases

Fasting plasma homocysteine level and the related clinical findings were analysed in 240 consecutive patients with venous thromboembolism. Hyperhomocysteinemia, defined as a plasma level above 20 micromol/l (corresponding to the percentile 95th in the controls), was present in 11.2% of the patients. Plasma homocysteine level was similar in patients presenting with either deep venous thrombosis, pulmonary embolism or both conditions. It was significantly higher in patients with primary (unprovoked) VTE than in patients with secondary disease (associated with at least one risk factor): 12.3 vs. 9.55 micromol/l (p < 0.005). Mean homocysteine was higher in male than in female patients (14.51 vs. 12.9 micromol/l, p < 0.05) and increased significantly with age. Hyperhomocysteinemia was more frequent in patients with relapsing disease (14 of 76, 18.4%) than in those presenting with a single episode (13 of 164, 7.9%) (p = 0.034). Furthermore, hyperhomocysteinemia was correlated with reduced protein C level (p = 0.013). In a multivariate analysis, two factors were significantly associated with hyperhomocysteinemia: older age (p < 0.0001) and idiopathic occurrence (p < 0.02). Since the frequency of homozygous MTHFR thermolabile variant was rather similar in patients and controls, testing for C677T mutation was not helpful in screening VTE patients. However, the homozygous mutation was significantly more prevalent among hyperhomocysteinemia patients, confirming its role in the genesis of hyperhomocysteinemia. According to its prevalence, to the putative role in venous and arterial disease and the availability of an effective and low-cost corrective therapy, hyperhomocysteinemia deserves interest, especially in the elderly and in the patients with idiopathic VTE disease.

[Evolution of homocysteine during ovarian stimulation for IVF or ICSI]

OBJECTIVE

To determine the homocysteine evolution during ovarian stimulation in IVF or ICSI protocols and in, a second time, to evaluate the role of hyperhomocysteine as thrombotic risk factor for the treated patients.

MATERIAL AND METHODS

Plasma homocysteine was determined three times for each of 31 women included in an IVF/ICSI program. Dosages were realised before stimulation, after gonadotrophin-releasing hormone agonist treatment (GnRH) and on the day of hCG injection. Vitamin B12 and folates were determined before stimulation. In case of hyperhomocysteinemia, a research of APCR (Activated Protein C Resistance) was realised.

RESULTS

Five hyperhomocysteinemia cases were discovered (16.12% of studied population). APCR was found in a patient with hyperhomocysteinemia (14 mumol/L, before stimulation). Molecular biology has confirmed an heterozygous mutation of factor V Leiden. During the ovarian stimulation the evolution of homocysteine was independent of the 17 beta oestradiol evolution.

CONCLUSION

The prevalence of hyperhomocysteinemia was not significative according to the limited size of the studied population. The increase of oestradiol during induction protocols is unrelated to the homocysteine level. This work must be continued with largest population to have better knowledge of the prevalence of hyperhomocysteinemia among women included in ovarian stimulation protocols.

Gene polymorphisms of homocysteine metabolism-related enzymes in Chinese patients with occlusive coronary artery or cerebral vascular diseases

The mutations in homocysteine (Hcy) metabolism-related enzyme genes including methylenetetrahydrofolate reductase (MTHFR) C677T, cystathionine beta-synthase (CBS) 844ins68, and methionine synthase (MS) A2756G have been identified as genetic risk factors for thromboembolic events. It has been noticed that these gene mutations have heterogeneous distributions among different ethnic groups or geographic areas. The data on the prevalence of the gene mutations in Chinese population is not yet available. In the present study, we have investigated the frequency of the MTHFR C677T, CBS 844ins68, and MS A2756G mutations in 102 patients with ischemic stroke (IS), 73 patients with myocardial infarction (MI) and 100 healthy controls. The distributive frequencies of the gene variations are as follows: In the IS, MI and control groups, the mutant homozygote for MTHFR C677T is 15 (14.7%), 8 (11.7%) and 16 (16.0%), respectively, and the T allele frequency is 37.7%, 33.6% and 39.5%, respectively; the heterozygote for CBS 844ins68 is 1 (1.0%), 1 (1.4%) and 5 (5.0%), respectively; the heterozygote for MS A2756G is 18 (17.6%), 14 (19.2%) and 17 (17.0%), and the G allele frequency is 8.8%, 11.0% and 9.5%, respectively. The carrier of both MS A2756G and MTHFR C677T (combined mutations) is 14 (12.7%), 8(11.0%) and 12(12.0%), respectively. There is no statistically significant difference between the patient groups and the control group in the frequencies of these single mutation or combined mutations. The heterozygosity of CBS 844ins68 yields an odds ratio (OR) of 0.19 (95% confidence interval (CI) 0.02-1.43) for IS and 0.26 (95% CI 0.03-2.31) for MI. The T allele of MTHFR C677T yields an OR of 0.93 for IS (95% CI 0.62-1.39) and 0.77 for MI (95% CI 0.50-1.21). The G allele of MS A2756G yields an OR of 0.92(95% CI 0.47-1.81) for IS and 1.17 (95% CI 0.58-2.37) for MI. Our results suggest that neither single mutation nor combined mutations in MTHFR C677T, CBS 844ins68 and MS A2756G represent an independent risk factor for increasing IS and coronary artery disease risks in Chinese population. However, CBS 844ins68 may be a protective factor against vascular thromboembolic disease. The prevalence of CBS 844ins68 and MS A2756G in Chinese population is obviously lower than in Western Caucasian population.

Antiepileptic drugs as independent predictors of plasma total homocysteine levels

Low folate levels have consistently been reported in patients with epilepsy on phenytoin (PHT), phenobarbital (PB) and primidone (PRD), while data on valproate (VPA) are conflicting. Furthermore, antiepileptic drugs (AEDs) may be associated with high levels of plasma total homocysteine (p-tHcy). Therefore, we have investigated the levels of p-tHcy, serum folate (S-FA) and erythrocyte folate (E-FA) in patients on PHT, PB and PRD (Group 1, n=21) and VPA (Group 2, n=24). Both groups had their own matched controls. Blood samples were drawn fasting and 6 h post methionine loading (6 h-PML). The Group 1 patients had fasting and 6 h-PML p-tHcy levels significantly higher than their controls (P=0.05 and <0.0001, respectively), and patients without dietary multivitamin supplementation (n=14), had lower fasting S-FA and E-FA levels than their controls (P=0.02 and 0.0003, respectively). The Group 2 patients had fasting and 6 h-PML levels of p-tHcy, S-FA and E-FA not different from their controls. In a multiple stepwise regression model comprising all subjects (n=90), the AEDs of Group 1 and the S-FA levels were independent predictors of p-tHcy levels. Thus, PHT, PB and PRD are associated with high p-tHcy and low folate levels, whereas VPA does not influence S-FA, E-FA and p-tHcy levels in adult patients.

Relevance of folate metabolism in the pathogenesis of colorectal cancer

The purpose of this review is to outline the principal mechanisms involved in folate metabolism and how they may relate to the pathogenesis of colorectal cancer (CRC). In recent years, mild folate depletion (low normal level) has been associated with an increased risk of developing certain cancers, in particular colorectal neoplasia. The epidemiologic and mechanistic evidence linking folate deficiency with carcinogenesis is reviewed, with a particular emphasis on colorectal neoplasia. Methylenetetrahydrofolate reductase (MTHFR) is a critical folate metabolizing enzyme, and a functional polymorphic variant of this enzyme, the so-called thermolabile variant, caused by a C677T transition in the MTHFR gene, is common in the general population. This review critically examines the evidence that suggests that carriers of this C677T variant may be at increased risk of developing colorectal neoplasia. Although folate depletion may predispose to the initiation of the neoplastic process, folate supplementation, on the other hand, might potentiate the progression of an already established early neoplastic clone (eg, a colorectal adenoma). This could have potential public health implications, given an increasingly widespread policy of folate supplementation of food staples.

Differences between cysteine and homocysteine in the induction of deoxyribose degradation and DNA damage

The effect of two naturally occurring thiols, such as cysteine and homocysteine, has been examined for their ability to induce deoxyribose degradation and DNA damage. Copper(II) ions have been added to incubation mixtures and oxygen consumption measurements have been performed in order to correlate the observed damaging effects with the rate of metal catalyzed thiol oxidation. Ascorbic acid plus copper has been used as a positive control of deoxyribose and DNA oxidation due to reactive oxygen species. Cysteine or homocysteine in the presence of copper ions induce the degradation of deoxyribose and the yield of 8-hydroxy-2'-deoxyguanosine (8-OHdG), although important differences are observed between the two thiols tested, homocysteine being less reactive than cysteine. DNA cleavage is induced by cysteine in the presence of copper(II) ions but not by homocysteine. Catalase and thiourea, but not superoxide dismutase (SOD), were shown to inhibit the damaging effects of cysteine on deoxyribose or DNA suggesting that H(2)O(2) and *OH radicals are responsible for the observed induced damage. The results indicate that there are differences between the damaging effects of the two thiols tested towards deoxyribose and DNA damage. The pathophysiological importance will be discussed.

Increased levels of homocysteine in patients with Crohn's disease are related to folate levels

OBJECTIVES

The risk for thrombotic events is increased in inflammatory bowel disease. The factors responsible for such a risk are poorly defined. Recently, an elevated homocysteine level is emerging as a risk factor for thrombosis. The aim of this study was to determine the levels of homocysteine in a well-characterized population of patients with Crohn's disease and to compare it to controls.

METHODS

The levels of homocysteine were determined in 105 well-characterized patients with Crohn's disease and 106 controls. The levels of folate and B12, which are involved in the metabolism of homocysteine were determined as well. Patients were treated with steroid preparations only.

RESULTS

Homocysteine levels were significantly elevated in the patient population. Elevated levels were correlated with both low B12 and folate levels, but folate deficiency turned out to be a more important factor. Low B12 levels were in correlation with the involvement of the terminal ileum. No correlation was found between homocysteine levels and either disease activity or involvement of the terminal ileum.

CONCLUSIONS

Homocysteine levels are increased in patients with Crohn's disease and this finding is inversely correlated with folate levels. Supplementation of folate to patients with Crohn's disease may be warranted.

The effect of different treatment regimens in reducing fasting and postmethionine-load homocysteine concentrations

OBJECTIVES

To determine the homocysteine-lowering effect of different treatment regimens on both fasting and postmethionine-load plasma total homocysteine (tHcy) concentrations.

DESIGN

Descriptive study of consecutive hyperhomocysteinaemic subjects per treatment regimen. Homocysteine was measured in the fasting state and 6 h after methionine loading, both before and after 8 weeks of vitamin therapy. Hyperhomocysteinaemia was defined as a fasting tHcy and/or increase in tHcy (postmethionine-load minus fasting tHcy concentration) exceeding the 95th percentile of local controls.

SETTING

Outpatient clinic of internal medicine of a large non-academic teaching hospital.

SUBJECTS

One hundred and seventeen hyperhomocysteinaemic subjects (vascular patients and first-degree relatives).

INTERVENTIONS

There were four regimens: pyridoxine, 200 mg; folic acid, 5 mg; combination of folic acid 0.5 mg and pyridoxine 100 mg; and folic acid, 0.5 mg daily.

RESULTS

All regimens, except pyridoxine 200 mg, significantly reduced fasting tHcy without differences in the percentage reduction (32-38%). All regimens produced a significant reduction in the increase in tHcy and postmethionine-load tHcy. The reduction in postmethionine-load tHcy was smaller for pyridoxine 200 mg than for combination therapy. No differences were found in the percentage reduction (for both increase in tHcy and postmethionine-load tHcy) between folic acid 5 mg and folic acid 0.5 mg.

CONCLUSIONS

Monotherapy folic acid (0.5 mg daily) is the lowest effective therapy for reducing both fasting and postmethionine-load tHcy concentrations, with the same results as high-dose folic acid (5 mg daily). Pyridoxine has no additional value.

Transsulfuration in Saccharomyces cerevisiae is not dependent on heme: purification and characterization of recombinant yeast cystathionine beta-synthase

Cystathionine beta-synthase [CBS; L-serine hydro-lyase (adding homocysteine), EC 4.2.1.22] catalyzes the first committed step of transsulfuration in both yeast and humans. It has been established previously that human CBS is a hemeprotein but although the heme group appears to be essential for CBS activity, the exact function of the heme group is unknown. CBS activity is absent in heme deficient strains of Saccharomyces cerevisiae grown without heme supplementation. CBS activity can be restored by supplementing these strains with heme, implying that there is a heme requirement for yeast CBS. We subcloned, overexpressed and purified yeast CBS. The yeast enzyme shows absolute pyridoxal 5'-phosphate (PLP) dependence for activity but we could find no evidence for the presence of a heme group. Given the degree of sequence and mechanistic similarity between yeast and human CBS, this result indicates that heme is unlikely to play a direct catalytic role in the human CBS reaction mechanism. Further characterization revealed that, in contrast to human CBS, S-adenosylmethionine (AdoMet) does not activate yeast CBS. Yeast CBS was found to be coordinately regulated with proliferation in S. cerevisiae. This finding is the most likely explanation of the observed apparent heme dependence of transsulfuration in vivo.

The relation of plasma total homocysteine levels to prevalent cardiovascular disease in older patients with ischemic stroke

The objectives of this study were to describe the distribution of serum levels of total homocysteine (HCys) in a sample of older patients consecutively admitted following acute ischemic cerebral stroke, as compared with healthy controls, and to test for possible relationships of HCys levels to some of the prevalent cardiovascular diseases in these stroke patients. One hundred and thirty-seven stroke patients and 132 healthy controls (age > or =60) participated in this study. HCys levels were determined by HPLC method with fluorescence detection. Correlates of HCys levels and clinical data were examined. The results showed that stroke patients (mean age 74.6+/-9.2) had higher HCys levels as compared with controls (13.8 and 9.8 respectively, p<0.001). Advanced age, male gender, absence of diabetes and a positive history of previous myocardial infarction were the factors associated with HCys levels higher than 10 mmol/L (Odds ratio 2.72, 2.54, 3.12, 3.55, respectively). We conclude that hyperhomocysteinemia is prevalent in older patients with acute ischemic stroke. Few factors associated with increased risk for hyperhomocysteinemia in these stroke patients were identified. The study supports earlier observations regarding elevated HCys levels in stroke patients and increased prevalence of associated cardiovascular disease.

A common mutation in the methylenetetrahydrofolate reductase gene is a determinant of hyperhomocysteinemia in epileptic patients receiving anticonvulsants

Hyperhomocysteinemia is a condition caused by both genetic and nongenetic factors. To determine whether a common methylenetetrahydrofolate reductase (MTHFR) variant is related to elevated homocysteine concentrations in epileptic patients receiving anticonvulsants, we investigated the plasma total homocysteine (tHcy) level, folate level, and MTHFR 677 C --> T mutation using a polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis with HinfI digestion in 103 patients with epilepsy and 103 normal controls. The prevalence of hyperhomocysteinemia (> or = 11.4 micromol/L, 90th percentile of control group) was higher in patients than in controls (25% v 10.0%, P = .007). The homozygosity for the 677 C --> T mutation of MTHFR was associated with elevated tHcy and low folate levels. The magnitude of hyperhomocysteinemia in MTHFR TT homozygotes was more pronounced in epileptic patients than in controls (18.2 +/- 1.6 v 9.1 +/- 1.2 micromol/L, P = .04). In epileptic patients, hyperhomocysteinemia was more frequent in MTHFR TT genotypes versus CT or CC genotypes (58% v 17% and 16%, P < .001). Multiple logistic regression analysis showed that MTHFR TT genotype was an independent predictor of hyperhomocysteinemia in epileptic patients receiving anticonvulsants (phenytoin and carbamazepine but not valproic acid), suggesting that gene-drug interactions induce hyperhomocysteinemia. These findings indicate that epileptic patients receiving anticonvulsants may have a higher folate requirement to maintain a normal tHcy level, especially homozygotes for MTHFR 677 C --> T mutation.

Evaluation of hyperhomocysteinaemia in children with stroke

Hyperhomocysteinaemia is associated with an increased risk of arterial vascular disease and thrombosis in adults. Our aim was to study the association of hyperhomocysteinaemia and stroke in children. Since some patients who had suffered a stroke developed seizures and received treatment with anti-epileptic (antifolate) drugs, we also examined the possible interaction between anti-epileptic drugs and hyperhomocysteinaemia. Plasma total homocysteine was measured in 68 children with stroke (23 of the 68 were taking anti-epileptic drugs) and 100 children undergoing anti-epileptic treatment but without history of stroke, and we compared the values with our reference values for similar ages (n = 195). Total homocysteine was determined by high profile liquid chromatography with fluorescence detection. Hyperhomocysteinaemia was defined as a homocysteine concentration above the 95th percentile for the reference values. Significant differences were found in total homocysteine values of children with stroke and those taking anti-epileptic drugs compared with our reference values for similar ages, except for the adolescent group. Total homocysteine values above the 95th percentile for the reference values were found in 36% of patients with stroke and 28% of children on anti-epileptic treatment. Total homocysteine concentrations in the 23 patients with both stroke and anti-epileptic drug treatment were similar to those of untreated patients with stroke in all age groups. In summary, systematic screening for hyperhomocysteinaemia should be included in the protocol to investigate the aetiology of stroke, even in paediatrics. Anti-epileptic treatment in children with stroke may be responsible for the mild hyperhomocysteinaemia observed in some of them. A dietary supplement of folate may be of benefit in children with stroke and in patients taking anti-epileptic drugs.