Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MTHFR is a critical enzyme that regulates the metabolism of folate and methionine, both of which are important factors in DNA methylation and synthesis. Subjects with the 677C-->T variant have impaired remethylation of Hcy to methionine that could determine hyperhomocysteinemia. Remethylation of Hcy into methionine and DNA methylation are also affected by MTX treatment. Thus, a combined effect between MTX and reduced activity of the MTHFR 677C-->T polymorphism could occur, leading to toxicity. In a clinical trial, 43 ovarian cancer patients were treated with low doses of MTX. During MTX therapy, 12 patients (27.9%) developed G3/4 WHO toxicity. In these 12 patients, we observed 6 G3/4 thrombocytopenias, 1 G3 neutropenia, 1 G3 anemia, 9 G3 mucositis cases and 1 G4 mucositis case. A significant association was observed between toxicity and TT MTHFR 677 genotype (p < 0.0001). G3/4 toxicity occurred in 10 of 13 (77%), 1 of 17 (6%) and 1 of 13 (8%) patients with the TT, CT and CC MTHFR genotypes, respectively. According to the logistic regression model, patients with the TT genotype had a relative risk of 42.0 (95% CI 4.2-418.6) of developing G3/4 toxicity compared to patients with the CC and CT genotypes. Patients with the TT genotype had Hcy plasma levels after MTX therapy significantly (p = 0.0001) higher than basal levels (mean +/- SD = 16.71 +/- 4.72 vs. 12.48 +/- 3.57 micromol/l); moreover, they also had higher Hcy plasma levels after MTX than patients with other MTHFR 677 genotypes (CC mean +/- SD = 9.87 +/- 3.61 micromol/l and CT mean +/- SD = 11.48 +/- 3.13 micromol/l). Finally, significant associations were observed between G3/4 WHO toxicity and higher Hcy plasma levels after MTX treatment (p = 0.0004). In conclusion, our data suggest that the TT MTHFR 677 genotype is associated with marked MTX-induced hyperhomocysteinemia and could represent a pharmacogenetic marker for toxicity after chronic treatment with low doses of MTX.
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PMID:Effect of methylenetetrahydrofolate reductase 677C-->T polymorphism on toxicity and homocysteine plasma level after chronic methotrexate treatment of ovarian cancer patients. 1247 11

Atherosclerosis is a multifaceted process which may be initiated by various insults to vascular endothelium. Independently of the nature of the offending factor, the endothelial dysfunction that results from the initial insult is characterized by increased adhesiveness of the endothelium to leukocytes and platelets and by the synthesis of vasoactive molecules, cytokines and procoagulant factors. This defensive response is characterized by classical inflammatory changes and may lead to plaque formation, luminal obstruction and plaque rupture. Factors involved in arterial damage in end-stage renal disease (ESRD) span from classical risk factors to disease-peculiar factors (anemia, secondary hyperparathyroidism and exposure to bioincompatible dialysis membranes and/or contaminated dialysis fluid) and to emerging and novel risk factors such as hyperhomocysteinemia, infections and accumulation of the endogenous inhibitor of NO synthase, asymmetric dimethylarginine (ADMA). There is strong and consistent evidence that acute phase reactants like C-reactive protein and cytokines like IL-beta, TNF-alpha and IL-6 are independently associated with death and atherosclerosis in ESRD patients. The experimental and epidemiological data collected thus far coherently show that endothelial dysfunction resulting from inflammation may promote abnormal vascular behavior and thrombosis in ESRD. There are several possible therapeutic approaches for reducing the risk excess associated with inflammation in ESRD. These possibilities range from drugs interfering with the angiotensin system or with adrenergic activity to anti-inflammatory and antilipid agents to vitamins, antioxidants, to the amino acid precursor of nitric oxide, L-arginine, and perhaps to antibiotics. The intellectual framework is well delineated but very few controlled trials have been performed or are underway in patients with ESRD.
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PMID:Inflammation and atherosclerosis in end-stage renal disease. 1256 58

Cardiovascular (CV) disease in uremic patients is a major concern to the nephrologist because it represents the main cause of morbidity and mortality in chronic renal failure patients, both predialysis and while on dialysis therapy. CV mortality is 3 to 20 times higher in dialysis patients than in the general population at similar age. Of note, a high prevalence of CV comorbidity is already present at start of maintenance dialysis, and is predictive of subsequent mortality on dialysis. CV disease progresses over years prior to the onset of ESRD, because risk factors develop from the early stage of chronic renal insufficiency. However, CV disease may be prevented or attenuated in patients who benefit from early, regular care of CV risk factors. Mechanisms of uremic cardiopathy, the major cause of mortality in uremic patients, are multifactorial and their effects are cumulative. Risk factors for left ventricular hypertrophy are hypertension, anemia, fluid overload and arteriosclosis, all of which are amendable by therapy. Risk factors for accelerated atherosclerosis, responsible for ischemic cardiopathy and myocardial infarction, are both common factors (e.g., hypertension, tobacco smoking and diabetes) and factors more specific for the uremic state (e.g., dyslipidemia, hyperhomocysteinemia and oxidative stress), all of which also are amendable by proper therapy. As a result, mixed hypertensive and ischemic cardiomyopathy develops, ultimately leading to cardiac failure, together with accidents resulting from valvular and arterial calcifications (favored by calcium-phosphate disorders), and from occlusion of coronary, cerebral and peripheral arteries. Cardioprotective therapy thus has become a cornerstone in the management of chronic renal failure patients, in conjunction with renoprotective therapy. Cardioprotective strategy involves optimal treatment of hypertension, anemia, fluid overload, dyslipidemia, hyperhomocysteinemia and calcium-phosphate disorders, and smoking cessation. To achieve a maximal efficacy, such treatment has to be initiated as early as possible in the course of renal failure. Because of its complexity, the integrated combined nephrotective and cardioprotective therapy requires early and sustained guidance by a nephrologist throughout the whole predialysis period.
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PMID:[Cardioprotection: an essential component for predialysis chronic renal failure treatment]. 1272 13

Patients with end-stage renal disease face a particularly high risk of cardiovascular disease and total mortality. Part of their increased risk is due to a higher prevalence of established risk factors, such as arterial hypertension, diabetes, smoking, and anemia. Hypertension and diabetes have a very high prevalence in dialysis patients and play a major role in their high mortality and morbidity. Hyperparathyroidism, hyperhomocysteinemia and disordered lipid metabolism represent factors that are peculiarly altered by the uremic state. Inflammatory processes, high sympathetic activity, and the accumulation of an endogenous inhibitor of NO synthase (ADMA), have recently emerged as cardiovascular risk factors of paramount importance. Sleep apnea has been linked with nocturnal hypertension and could be implicated in the high prevalence of concentric hypertrophy of the left ventricle in these patients. Hypertension control, as well as appropriate treatment of anemia and cessation of smoking, constitutes a fundamental area of intervention in dialysis patients. It appears possible that, in the near future, control of chronic inflammatory processes of high sympathetic activity and endothelial dysfunction will further help to curb the exceedingly high cardiovascular mortality of patients on chronic dialysis treatment.
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PMID:Traditional and emerging cardiovascular risk factors in end-stage renal disease. 1275 78

Hyperhomocysteinemia is recognized as an independent risk factor for cardiovascular disease, especially atherosclerosis, in adult patients with chronic renal failure (CRF). However, there is little information about the relationship between plasma homocysteine levels and left ventricular hypertrophy. The aim of this study was to determine plasma homocysteine levels and risk factors for left ventricular hypertrophy and to investigate the relationship between plasma homocysteine concentration and left ventricular mass index (LVMI) in children with CRF. The homocysteine level was measured by high-performance liquid chromatography and LVMI was calculated using echocardiographic findings in 27 children with CRF and 16 healthy controls. The mean LVMI and mean plasma homocysteine concentration in the CRF group, especially in patients with end-stage renal disease, were statistically higher than the control group ( P<0.05). There was no correlation between LVMI and plasma homocysteine concentration. There was a positive correlation between plasma homocysteine concentration and serum creatinine level. There was a positive correlation of LVMI with creatinine and blood pressures (systolic, diastolic, and mean arterial pressure). There was a negative correlation of LVMI with hemoglobin level in multiple linear regression analysis. In our view homocysteine does not have a direct effect on left ventricular structure and left ventricular hypertrophy is the end organ damage associated with hypertension, anemia, and CRF. More prospective studies are needed to better clarify the inter-relationships of plasma homocysteine level and left ventricular structure in children with CRF.
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PMID:Homocysteine and left ventricular hypertrophy in children with chronic renal failure. 1465 62

Pernicious anemia is a common cause of megaloblastic anemia throughout the world and especially in persons of European or African descent. Dietary deficiency of vitamin B12 due to vegetarianism is increasing and causes hyperhomocysteinemia. The breast-fed infant of a vitamin B12-deficient mother is at risk for severe developmental abnormalities, growth failure, and anemia. Elevated methylmalonic acid and/or total homocysteine are sensitive indicators of vitamin B12-deficient diets and correlate with clinical abnormalities. Dietary vitamin B12 deficiency is a severe problem in the Indian subcontinent, Mexico, Central and South America, and selected areas in Africa. Dietary vitamin B12 deficiency is not prevalent in Asia, except in vegetarians. Areas for research include intermittent vitamin B12 supplement dosing and better measurements of the bioavailability of B12 in fermented vegetarian foods and algae.
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PMID:Vitamin B12 deficiency as a worldwide problem. 1518 23

About 1,000 children develop end-stage renal disease (ESRD) each year in the United States and about 5,000 children are currently receiving dialysis. Children who develop ESRD are eligible to receive renal replacement therapy, including renal transplantation. There are inherent risks associated with transplantation, including renal insufficiency, infections, post-transplant lymphoproliferative disorder, and cardiovascular disease (CVD). Potential risk factors for CVD in pediatric renal transplant recipients include renal insufficiency, hyperlipidemia, hyperhomocysteinemia, inflammation, malnutrition, anemia, and hyperglycemia/insulin resistance. Despite evidence that many children may possess various risk factors for CVD post-renal transplantation, there are very few studies that have attempted to assess the link between these risk factors and CVD in pediatric renal transplant recipients.
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PMID:Risk factors for cardiovascular disease in pediatric renal transplant recipients. 1526 67

The main problem nephrologists have to face today is the very high patient morbidity and mortality. A number of traditional and non-traditional risk factors have a role; among these anaemia, hypertension, dislipidemia, abnormalities in calcium-phosphate metabolism, hyperhomocysteinemia and endothelial dysfunction. An important innovation in the field of hemodialysis has been the availability of high-permeable and high-flux membranes, characterized by a high biocompatibility and ultrafiltration coefficient. The development of automatic systems to control ultrafiltration has enabled the utilisation of these membranes in the clinical setting (high-flux hemodialysis, hemofiltration, hemodiafiltration). It is common opinion that high-flux membranes can positively influence cardiovascular instability, but this has not been confirmed by clinical trials. Although preliminary data indicated a favorable effect on the correction of anemia in patients treated with high-permeable membranes, randomized trials have not shown a significant effect. Better control of anemia could be possible by means of on-line treatments, given their higher removal of medium- and large molecules and reduced microbiological and pyrogenic contamination of the dialysate. A number of analyses showed a lower incidence of bone cysts and/or carpal tunnel syndrome in patients treated with high-flux membranes compared to low-flux ones. High-flux treatments could reduce morbidity and mortality in hemodialysis patients. However, despite its large sample size, the HEMO Study has not been capable of showing a statistically significant effect of higher dialysis dose and high-flux membranes on survival and morbidity. The MPO study has been expressively designed to do a prospective evaluation of the long-term effect of membrane permeability on clinical outcomes. These results are greatly awaited.
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PMID:[Clinical dialysis: new problems and new prospects]. 1535 50

The cblE type of homocystinuria is a rare autosomal recessive disorder caused by impaired reductive activation of methionine synthase. Although earlier biochemical studies proposed that the methionine synthase enzyme might be activated by two different reducing systems, mutations were reported in only the methionine synthase reductase gene (MTRR) in cblE patients. The pathogenicity of MTRR mutations, however, has not yet been tested functionally. We report on nine patients of European origin affected by the cblE type of homocystinuria. They presented between 2 weeks and 3 years of age (median age 4 weeks) with anemia, which was macrocytic in only three patients, and with neurological involvement in all but two cases. Bone marrow examination performed in seven patients showed megaloblastic changes in all but one of them. All patients exhibited moderate to severe hyperhomocysteinemia (median plasma total homocysteine [Hcy] 92 mumol/L, range 44-169), while clearly reduced methionine was observed only in four cases. Pathogenic mutations were identified in both parental alleles of the MTRR gene in all patients. Five known (c.903+469T>C, c.1361C>T, c.1459G>A, c.1557-4_1557+3del7, and c.1622_1623dupTA) and three novel mutations (c.7A>T, c.1573C>T, and c.1953-6_1953-2del5) were detected. Importantly, transfection of fibroblasts of cblE patients with a wild-type MTRR minigene expression construct resulted in a significant approximately four-fold increase of methionine synthesis, indicating correction of the enzyme defect. Our study shows a link between a milder predominantly hematological presentation and homozygosity for the c.1361C>T mutation, but no other obvious genotype-phenotype correlation. The identification of mutations in the MTRR gene, together with restoration of methionine synthesis following MTRR minigene expression in cblE cells confirms that this disease is caused by defects in the MTRR gene.
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PMID:cblE type of homocystinuria due to methionine synthase reductase deficiency: functional correction by minigene expression. 1571 22

Cardiovascular disease is the leading cause of morbidity and mortality following renal transplantation. Because many renal transplant recipients die with functioning grafts, deaths resulting from cardiovascular disease have became an increasingly important cause of graft loss, particularly after the first post-transplantation year. Moreover, a contribution of some cardiovascular risk factors to renal allograft dysfunction has been demonstrated. A number of observational studies suggest that cardiovascular disease is more common in renal transplant patients than in the general population. The excessive risk for cardiovascular disease is related to a high prevalence and accumulation of atherogenic risk factors before and after transplantation. Hypertension, post-transplantation diabetes and hyperlipidemia are well-recognized risk factors for the development of cardiovascular events after renal transplantation and are strongly associated with immunosuppressive therapy. Progressive renal dysfunction may also influence the risk of cardiovascular complications after renal transplantation. The elevated risk may also be caused by non- traditional risk factors such as anaemia, adhesion molecules, hyperhomocysteinemia, microinflammatory state, abnormal coagulation and oxidative stress. To prevent post-transplantation cardiovascular disease it is crucial to define the etiological risk factors. Some risk factors can be modified, and for some of these, there is strong evidence from studies in the general population that intervention improves survival. Given the significant morbidity and mortality of cardiovascular disease in renal transplant recipients, aggressive treatment intervention for potentially modifiable factors are strongly advocated after transplantation. In addition to treatment intervention, risk management should also involve tailoring the immunosuppressive regimen to minimize both direct and indirect cardiovascular risks. In this article we attempted to review and quantify the post-transplant risk factors for cardiovascular disease as well as offer suggestions on optimizing the therapy or treatment strategies to minimize the risk of cardiovascular complications in renal transplant patients. Reduction of cardiovascular morbidity and mortality can improve not only the life expectancy and quality of life of the transplant recipients but also their graft function and survival.
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PMID:[Cardiovascular disease after renal transplantation]. 1573 47


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