OBJECTIVETo screen out differentially expressed microRNAs (miRNAs) in the plasma of children with methylmalonic acidemia (MMA), to determine the expression of miR-9-1 in plasma and to preliminarily evaluate the significance of miR-9-1 as a biomarker in MMA.

METHODSPlasma was obtained from 17 MMA children, 10 hyperhomocysteinemia (HHcy) children without MMA (HHcy group), and 10 normal controls. Of 17 MMA children, 12 had HHcy (MMA+HHcy group), and 5 had no HHcy (MMA group). The differentially expressed miRNAs were screened out by miRNA microarray. Differentially expressed miR-9-1 was selected, and plasma miR-9-1 levels were determined by RT-PCR. Urine was collected from MMA patients who received vitamin B12 treatment, and plasma miR-9-1 levels were determined by RT-PCR after treatment.

RESULTSThe miRNA microarray analysis showed that 26 miRNAs were differentially expressed, among which 16 miRNAs (including miR-9-1) were down-regulated over 2 times, while 10 miRNAs were up-regulated over 2 times. The MMA+HHcy , MMA and HHcy groups had significantly down-regulated miR-9-1 compared with the normal control group (P<0.01). The patients who showed a good response to vitamin B12 treatment had significantly increased plasma miR-9-1 levels, without significant difference compared with the normal control group.

CONCLUSIONSPlasma miR-9-1 is significantly down-regulated in MMA patients, but it is significantly up-regulated after vitamin B12 treatment, suggesting that miR-9-1 may act as a biomarker in monitoring the progression of MMA.

Adolescent ; Amino Acid Metabolism, Inborn Errors ; genetics ; Child ; Female ; Humans ; Hyperhomocysteinemia ; genetics ; Male ; MicroRNAs ; blood

A case of combined methylmalonic aciduria and homocysteinemia presenting with hydrocephalus as an early manifestation was reported for its rarity to see and to discuss the relationship between metabolic diseases and hydrocephalus by literature review. The case was an infant with seizures and hydrocephalus as an early manifestation of the disease, combined with macrocyticanemia, development retardation and visual hearing function lesions. The EEG showed hypsarrhythmia and the MRI showed hydrocephalus. Plasma homocysteinemia level increased (143.06 umol/L) and urine methylmalonic aciduria was 1483 times beyond normal. Based on gene analysis results and increased methylmalonic aciduria and homocysteinemia levels, combined methylmalonic aciduria and homocysteinemia was confirmed, presenting CblC defect (gene mutations homozygous for c.609G>A). After treatment by venous injection of vitamin B12, oral folic acid and betaine, seizures were controlled and development was progressive with ventricle retraction. It was concluded that hydrocephalus can be the early presentation in children with combined methylmalonic aciduria and homocysteinemia. Doctors should carry out metabolic disease screening for patients with hydrocephalus, especially when the cause of hydrocephalus is uncertain.
Amino Acid Metabolism, Inborn Errors ; complications ; Humans ; Hydrocephalus ; etiology ; Hyperhomocysteinemia ; complications ; Infant ; Male

Hyperhomocysteinemia (HHcy) is considered to be an independent risk factor for cardiovascular diseases, but the molecular mechanisms underlying its pathogenesis are not fully understood. Endothelial dysfunction is a key initiating factor in the pathogenesis of atherosclerosis, which is commonly observed in almost all HHcy-induced vascular diseases. HHcy promotes oxidative stress, inhibits nitric oxide production, suppresses hydrogen sulfide signaling pathway, promotes endothelial mesenchymal transition, activates coagulation pathways, and promotes protein N-homocysteination and cellular hypomethylation, all of which can cause endothelial dysfunction. This article reviews the specific links between HHcy and endothelial dysfunction, and highlights recent evidence that endothelial mesenchymal transition contributes to HHcy-induced vascular damage, with a hope to provide new ideas for the clinical treatment of HHcy-related vascular diseases.
Humans ; Atherosclerosis ; Cardiovascular Diseases ; Endothelium, Vascular ; Homocysteine/metabolism* ; Hyperhomocysteinemia/complications* ; Oxidative Stress ; Risk Factors

Chronic stress is generally accepted as the main risk factor in the development of cognitive decline; however, the underlying mechanisms remain unclear. Previous data have demonstrated that the levels of homocysteine (Hcy) are significantly elevated in the plasma of stressed animals, which suggests that Hcy is associated with stress and cognitive decline. To test this hypothesis, we analyzed the cognitive function, plasma concentrations of Hcy, and brain-derived neurotropic factor (BDNF) levels in rats undergoing chronic unpredicted mild stress (CUMS). The results showed that decreased cognitive behavioral performance and decreased BDNF transcription and protein expression were correlated with hyperhomocysteinemia (HHcy) levels in stressed rats. Diet-induced HHcy mimicked the cognitive decline and BDNF downregulation in the same manner as CUMS, while Hcy reduction (by means of vitamin B complex supplements) alleviated the cognitive deficits and BDNF reduction in CUMS rats. Furthermore, we also found that both stress and HHcy disturbed the DNA methylation process in the brain and induced DNA hypermethylation in the BDNF promoter. In contrast, control of Hcy blocked BDNF promoter methylation and upregulated BDNF levels in the brain. These results imply the possibility of a causal role of Hcy in stress-induced cognitive decline. We also used ten-eleven translocation (TET1), an enzyme that induces DNA demethylation, to verify the involvement of Hcy and DNA methylation in the regulation of BDNF expression and the development of stress-related cognitive decline. The data showed that TET1-expressing viral injection into the hippocampus inhibited BDNF promoter methylation and significantly mitigated the cognitive decline in HHcy rats. Taken together, novel evidence from the present study suggests that Hcy is likely involved in chronic stress-induced BDNF reduction and related cognitive deficits. In addition, the negative side-effects of HHcy may be associated with Hcy-induced DNA hypermethylation in the BDNF promoter. The results also suggest the possibility of Hcy as a target for therapy and the potential value of vitamin B intake in preventing stress-induced cognitive decline.
Animals ; Brain-Derived Neurotrophic Factor/metabolism* ; Cognitive Dysfunction/complications* ; DNA Methylation ; Homocysteine/metabolism* ; Hyperhomocysteinemia/metabolism* ; Rats ; Stress, Psychological/physiopathology*

To investigate the effect of stress on homocysteine metabolism in the rat and explore the mechanism as well as the key regulatory link of stress-induced hyperhomocysteinemia, male Wistar rats were treated with restraint stress while control rats received routine treatment. By HPLC-fluorometry, the homocysteine level in rat plasma was determined. Cystathionine beta-synthase (CBS) activity in blood, heart, liver and kidney was measured by radioisotope assay using [(14)C]-serine as the labeled substrate. Total RNA was isolated from rat liver after restraint stress. RT-PCR and Northern blot were used to estimate the level of CBS mRNA. The results showed that hyperhomocysteinemia was induced by restraint stress. The highest CBS enzyme activity was seen in rat livers. A decrease in hepatic activities of CBS was found in restraint stress rats. The 29.4% +/-2.5% reduction in the activity of CBS was accompanied by a 44.1% +/-3.4% decrease in its mRNA level. CBS enzyme activity was slightly elevated in the kidney of stressed rats while it was almost undeterminable in the cardiovascular system. The study suggests that stress leads to an inhibition of the transsulfuration pathway in homocysteine metabolism. The hepatic CBS influenced by stress at the level of transcription exerts a profound effect on the circulating levels of homocysteine. The liver is the key organ where stress affects homocysteine metabolism.
Animals ; Down-Regulation ; Homocysteine ; metabolism ; Hyperhomocysteinemia ; blood ; etiology ; Male ; Rats ; Rats, Wistar ; Restraint, Physical ; Stress, Physiological ; complications ; metabolism

Arteriosclerosis and its complications, such as heart attack and stroke, are the major causes of death in developed countries. It was believed that age, hyperlipidemia, hypertension, diabetes and smoking are common risk factors for cardiovascular disease. In addition, overwhelming clinical and epidemiological studies have identified homocysteine (Hcy) as a significant and independent risk factor for cardiovascular disease. In healthy individuals, plasma Hcy is between 5 and 10 micromol/L. One cause of severe hypehomocys- teinemia (HHcy) is the deficiency of cystathionine beta-synthase (CBS), which converts Hcy to cystathionine. CBS homozygous deficiency results in severe HHcy with Hcy levels up to 100 to 500 micromol/L. Patients with severe HHcy usually present with neurological abnormalities, premature arteriosclerosis. It has been reported that lowering plasma Hcy improved endothelial dysfunction and reduced incidence of major adverse events after percutaneous coronary intervention. The mechanisms by which Hcy induces atherosclerosis are largely unknown. Several biological mechanisms have been proposed to explain cardiovascular pathological changes associated with HHcy. These include: (1) endothelial cell damage and impaired endothelial function; (2) dysregulation of cholesterol and triglyceride biosynthesis; (3) stimulation of vascular smooth muscle cell proliferation; (4) thrombosis activation and (5) activation of monocytes. Four major biochemical mechanisms have been proposed to explain the vascular pathology of Hcy. These include: (1) autooxidation through the production of reactive oxygen species; (2) hypomethylation by forming SAH, a potent inhibitor of biological transmethylations; (3) nitrosylation by binding to nitric oxide or (4) protein homocysteinylation by incorporating into protein. In summary, our studies, as well as data from other laboratories support the concept that Hcy is causally linked to atherosclerosis, and is not merely associated with the disease. Although folic acid, vitamin B12 and B6 can lower plasma Hcy levels, the long-term effects on cardiovascular disease risk are still unknown and judgments about therapeutic benefits await the findings of ongoing clinical trials.
Animals ; Atherosclerosis ; etiology ; physiopathology ; Cystathionine beta-Synthase ; deficiency ; genetics ; Homocysteine ; metabolism ; Humans ; Hyperhomocysteinemia ; complications ; physiopathology ; Reactive Oxygen Species ; metabolism

C677T mutation in the gene encoding 5,10-methylenetetrahydrofolate reductase (MTHFR) predisposes to hyperhomocysteinemia in vivo and is known to be one of the causes of perinatal ischemic stroke. As MTHFR plays a role in the metabolism of homocysteine, C677T mutation may account for reduced enzymatic activity resulting in hyperhomocysteinemia. This may be prevented by introducing activity-enhancing coenzymes such as folic acid, vitamin B6, and B12. Though C677T mutation is known as a significant risk factor for cerebral infarction, reported cases of cerebral infarction among affected neonates are scarce. This report describes a case of a neonate homozygous for C677T mutation who had a perinatal ischemic stroke, born in a mother whose folic acid and nutritional consumption had been reduced during pregnancy.
Cerebral Infarction* ; Coenzymes ; Folic Acid ; Homocysteine ; Humans ; Hyperhomocysteinemia ; Infant, Newborn ; Metabolism ; Mothers ; Oxidoreductases ; Pregnancy ; Risk Factors ; Stroke ; Vitamin B 6

We investigated the effects of dietary folate supplementation on plasma homocysteine, vitamin B12 and hepatic levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in diet-induced hyperhomocysteinemic rats. All animals were fed 0.3% homocysteine diet for 2 weeks, then they were placed either on a 0.3% homocystine or no homocystine with or without 8 mg/kg folate diet for 8 weeks. Homocystine diet induced hyperhomocysteinemia up to 3.5-fold at 10 weeks (28.0+/-4.8 micromol/l vs. 7.9+/-0.3 micromol/l). Dietary folate supplementation caused a significant decrease in plasma homocysteine levels which had been increased by a homocystine-diet. Also, dietary folate supplementation made them return to control levels at 4 wk when the diet was free of homocystine. Plasma folate levels were markedly decreased with homocystine diet with no folate supplementation. Plasma vitamin B12 did not differ between groups. Dietary homocystine increased hepatic levels of SAM in folate supplementation group at 10 weeks (p<0.05). Dietary folate supplementation increased hepatic levels of SAM/SAH ratios in homocystine group (p<0.05). In conclusion, dietary folate supplementation can effectively ameliorate the detrimental effects of hyperhomocysteinemia.mia.
Animals ; Diet ; Folic Acid* ; Homocysteine ; Homocystine* ; Hyperhomocysteinemia* ; Metabolism* ; Plasma ; Rats* ; S-Adenosylhomocysteine ; S-Adenosylmethionine* ; Vitamin B 12

AIMTo explore the effect of hyperhomocysteinemia on vascular calcification and the underlying mechanism of it.

METHODSArterial calcification of Sprague-Dawley rats was induced by vitamin D3 plus nicotine. Hyperhomocysteinemia was established by feeding high methionine diet for six weeks and was assessed b y plasma total homocysteine (tHcy) level detected by HPLC method. Calcification was confirmed by von Kossa staining, measurement of calcium content, alkaline phosphatases (ALP) activity and osteocalcin (OC) concentration of vascular tissue. Lipid conjugated dienes formation were determined to reflecting the production of lipid peroxide.

RESULTSThe results showed that there were mass black granules deposited in aortic wall of the calcified rats by von Kossa staining. Calcium content, ALP activity, OC concentration in calcified rats increased by 8.09-fold, 45.57% and 2.81-fold compared with those of the control group (P < 0.01). Calcium content in calcified rats with high methionine diet increased by 34.29% compared with that of the calcified rats, while ALP activity and OC content decreased by 29.13% and 74.69% compared with that of the calcified rats. Lipid conjugated dienes formation in plasma of the rat with high methionine diet and of calcified rats with high methionine diet increased by 1.93 and 2.89-fold compared with those of the control group, respectively (P < 0.01), and in calcified rats with high methionine diet group was increased by 32.90% compared with that of high methionine diet group (P < 0.01).

CONCLUSIONHyperhomocysteinemia could promote vascular calcification, which might be mediated through the production of lipid peroxide.

Alkaline Phosphatase ; metabolism ; Animals ; Calcium ; metabolism ; Endothelium, Vascular ; Hyperhomocysteinemia ; metabolism ; pathology ; Lipid Peroxidation ; Male ; Methionine ; administration & dosage ; Osteocalcin ; analysis ; Rats ; Rats, Sprague-Dawley ; Vascular Calcification ; metabolism ; pathology

OBJECTIVETo investigate the expressions of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) in the liver of mice with hyperhomocysteinemia (HHcy) and explore the mechanism of gluconeogenesis induced by homocysteine.

METHODSFifty mice were randomly divided into normal control group (n=25) and HHcy group (n=25) and fed with normal food and food supplemented with 1.5% methionine, respectively. After 3 months of feeding, the fasting blood glucose and insulin levels were determined, and HOMA insulin resistance index (HOMA-IR) was calculated. The expressions of G6Pase and PEPCK in the liver of mice were detected using RT-PCR and Western blotting.

RESULTSThe fasting blood glucose and insulin levels and HOMA-IR were significantly higher in HHcy group than in the control group (P<0.05). RT-PCR and Western blotting showed that the hepatic expressions of G6Pase and PEPCK mRNA and proteins increased significantly in HHcy group compared with those in the control group (P<0.05).

CONCLUSIONHomocysteine promotes gluconeogenesis to enhance glucose output and contribute to the occurrence of insulin resistance.

Animals ; Gluconeogenesis ; Glucose-6-Phosphatase ; metabolism ; Homocysteine ; blood ; Hyperhomocysteinemia ; metabolism ; Insulin Resistance ; Liver ; metabolism ; Male ; Mice ; Mice, Inbred Strains ; Phosphoenolpyruvate Carboxykinase (ATP) ; metabolism