Mild Hyperhomocyst(e)inemia

Background and Purpose —The pathogenesis of cervical artery dissection (CAD) remains unknown in most cases. Hyperhomocyst(e)inemia [hyperH(e)], an independent risk factor for cerebrovascular disease, induces damage in endothelial cells in animal cell culture. Consecutive patients with CAD and age-matched control subjects have been studied by serum levels of homocyst(e)ine and the genotype of 5,10-methylenetetrahydrofolate reductase ( MTHFR ). Methods —Twenty-six patients with CAD, admitted to our Stroke Unit (15 men and 11 women; 16 vertebral arteries, 10 internal carotid arteries), were compared with age-matched control subjects. All patients underwent duplex ultrasound, MR angiography, and/or conventional angiography. Results —Mean plasma homocyst(e)ine level was 17.88 μmol/L (range 5.95 to 40.0 μmol/L) for patients with CAD and 6.0±0.99 μmol/L for controls ( P <0.001). The genetic analysis for the thermolabile form of MTHFR in CAD patients showed heterozygosity in 54% and homozygosity in 27%; comparable figures for controls were 40% ( P =0.4) and 10% ( P =0.1), respectively. Conclusions —Mild hyperH(e) might represent a risk factor for cervical artery dissection. The MTHFR mutation is not significantly associated with CAD. An interaction between different genetic and environmental factors probably takes place in the cascade of pathogenetic events leading to arterial wall damage

One-carbon metabolism in children with marasmus and kwashiorkor

BACKGROUND: Kwashiorkor is a childhood syndrome of edematous malnutrition. Its precise nutritional precipitants remain uncertain despite nine decades of study. Remarkably, kwashiorkor\u27s disturbances resemble the effects of experimental diets that are deficient in one-carbon nutrients. This similarity suggests that kwashiorkor may represent a nutritionally mediated syndrome of acute one-carbon metabolism dysfunction. Here we report findings from a cross-sectional exploration of serum one-carbon metabolites in Malawian children. METHODS: Blood was collected from children aged 12-60 months before nutritional rehabilitation: kwashiorkor (N = 94), marasmic-kwashiorkor (N = 43) marasmus (N = 118), moderate acute malnutrition (N = 56) and controls (N = 46). Serum concentrations of 16 one-carbon metabolites were quantified using LC/MS techniques, and then compared across participant groups. FINDINGS: Twelve of 16 measured one-carbon metabolites differed significantly between participant groups. Measured outputs of one-carbon metabolism, asymmetric dimethylarginine (ADMA) and cysteine, were lower in marasmic-kwashiorkor (median µmol/L (± SD): 0·549 (± 0·217) P = 0·00045 & 90 (± 40) P \u3c 0·0001, respectively) and kwashiorkor (0·557 (± 0·195) P \u3c 0·0001 & 115 (± 50) P \u3c 0·0001), relative to marasmus (0·698 (± 0·212) & 153 (± 42)). ADMA and cysteine were well correlated with methionine in both kwashiorkor and marasmic-kwashiorkor. INTERPRETATION: Kwashiorkor and marasmic-kwashiorkor were distinguished by evidence of one-carbon metabolism dysfunction. Correlative observations suggest that methionine deficiency drives this dysfunction, which is implicated in the syndrome\u27s pathogenesis. The hypothesis that kwashiorkor can be prevented by fortifying low quality diets with methionine, along with nutrients that support efficient methionine use, such as choline, requires further investigation. FUNDING: The Hickey Family Foundation, the American College of Gastroenterology, the NICHD, and the USDA/ARS

Increasing breast milk betaine modulates Akkermansia abundance in mammalian neonates and improves long-term metabolic health

Accelerated postnatal growth is a potentially modifiable risk factor for future obesity. To study how specific breast milk components contribute to early growth and obesity risk, we quantified one-carbon metabolism-related metabolites in human breast milk and found an inverse association between milk betaine content and infant growth. This association was replicated in an independent and geographically distinct cohort. To determine the potential role of milk betaine in modulating offspring obesity risk, we performed maternal betaine supplementation experiments in mice. Higher betaine intake during lactation increased milk betaine content in dams and led to lower adiposity and improved glucose homeostasis throughout adulthood in mouse offspring. These effects were accompanied by a transient increase in Akkermansia spp. abundance in the gut during early life and a long-lasting increase in intestinal goblet cell number. The link between breast milk betaine and Akkermansia abundance in the gut was also observed in humans, as infants exposed to higher milk betaine content during breastfeeding showed higher fecal Akkermansia muciniphila abundance. Furthermore, administration of A. muciniphila to mouse pups during the lactation period partially replicated the effects of maternal breast milk betaine, including increased intestinal goblet cell number, lower adiposity, and improved glucose homeostasis during adulthood. These data demonstrate a link between breast milk betaine content and long-term metabolic health of offspring.info:eu-repo/semantics/acceptedVersio

Absorption and Tissue Distribution of Folate Forms in Rats: Indications for Specific Folate Form Supplementation during Pregnancy

Food fortification and folic acid supplementation during pregnancy have been implemented as strategies to prevent fetal malformations during pregnancy. However, with the emergence of conditions where folate metabolism and transport are disrupted, such as folate receptor alpha autoantibody (FR&alpha;Ab)-induced folate deficiency, it is critical to find a folate form that is effective and safe for pharmacologic dosing for prolonged periods. Therefore, in this study, we explored the absorption and tissue distribution of folic acid (PGA), 5-methyl-tetrahydrofolate (MTHF), l-folinic acid (levofolinate), and d,l-folinic acid (Leucovorin) in adult rats. During absorption, all forms are converted to MTHF while some unconverted folate form is transported into the blood, especially PGA. The study confirms the rapid distribution of absorbed folate to the placenta and fetus. FR&alpha;Ab administered, also accumulates rapidly in the placenta and blocks folate transport to the fetus and high folate concentrations are needed to circumvent or overcome the blocking of FR&alpha;. In the presence of FR&alpha;Ab, both Leucovorin and levofolinate are absorbed and distributed to tissues better than the other forms. However, only 50% of the leucovorin is metabolically active whereas levofolinate is fully active and generates higher tetrahydrofolate (THF). Because levofolinate can readily incorporate into the folate cycle without needing methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) in the first pass and is relatively stable, it should be the folate form of choice during pregnancy, other disorders where large daily doses of folate are needed, and food fortification

Characterization of 2-(methylamino)alkanoic acid capacity to restrict blood–brain phenylalanine transport in Pahenu2 mice: Preliminary findings

BACKGROUND: Our laboratory seeks a pharmacotherapeutic intervention for PKU that utilizes non-physiological amino acids (NPAAs) to block the accumulation of phenylalanine (Phe) in the brain. In previous studies (Vogel et al. 2013), methylation of the amino group of 2-aminoisobutyrate (AIB) provided an enhanced degree of selectivity for Phe restriction into the brain of Pah(enu2) mice in comparison to unmethylated AIB, leading to the hypothesis that 2-(methylamino)alkanoic acid analogs of AIB might represent targeted inhibitors of Phe accretion into the brain. METHODS: Pah(enu2) and control mice were intraperitoneally administered (500–750 mg/kg body weight, once daily; standard 19% protein diet) AIB, methyl AIB (MAIB), isovaline, and two MAIB analogs, 2-methyl-2-(methylamino)butanoic (MeVal) and 3-methyl-2-(methylamino)pentanoic (MePent) acids for one week, followed by brain and blood isolation for amino acid analyses using UPLC. RESULTS: In the brain, AIB significantly reduced Phe accretion in Pah(enu2) mice, while MeVal significantly improved glutamine and aspartic acids. Four of five test compounds improved brain threonine and arginine levels. AIB, MAIB and IsoVal significantly reduced blood Phe, with no effect of any drug intervention on other sera amino acids. CONCLUSIONS: Further evaluation of AIB and the 2-(methylamino)alkanoic acids as inhibitors of brain Phe accumulation in Pah(enu2) mice is warranted, with more detailed evaluations of route of administration, combinatorial intervention, and detailed toxicity studies

Tetrahydrobiopterin Concentrations in Normal and Coronary Artery Diseased Heart Tissue

Tetrahydrobiopterin (BH4) is an essential cofactor that controls the enzymatic activity of aromatic amino acid hydroxylases as well as all forms of nitric oxide synthase (NOS), which include endothelial (eNOS), neuronal (nNOS) and inducible (iNOS) isoforms [1]. In coronary arteries, reduced availability of BH4 in the endothelium causes decreased production of nitric oxide and an increase in eNOSderived production of reactive oxygen species including superoxide anion and hydrogen peroxide [2,3]. Studies have demonstrated that oxidative stress causes uncoupling of eNOS and endothelial dysfunction, which is associated with chemical inactivation of BH4 and its oxidation to dihydrobiopterin (BH2) [4]. There is mounting evidence that this mechanism plays a particularly important role in coronary artery disease (CAD). For instance, low BH4 and BH4/BH2 ratio have been found to be decreased in plasma of patients with CAD and in blood vessel wall [5]. BH4 levels are reported to be reduced in heart tissue from rodent models of cardiac ischemia that results in NOS decoupling [6-8].</p

Brain–blood amino acid correlates following protein restriction in murine maple syrup urine disease

BACKGROUND: Conventional therapy for patients with maple syrup urine disease (MSUD) entails restriction of protein intake to maintain acceptable levels of the branched chain amino acid, leucine (LEU), monitored in blood. However, no data exists on the correlation between brain and blood LEU with protein restriction, and whether correction in blood is reflected in brain. METHODS: To address this question, we fed intermediate MSUD mice diets of 19% (standard) and 6% protein, with collection of sera (SE), striata (STR), cerebellum (CE) and cortex (CTX) for quantitative amino acid analyses. RESULTS: LEU and valine (VAL) levels in all brain regions improved on average 28% when shifting from 19% to 6% protein, whereas the same improvements in SE were on average 60%. Isoleucine (ILE) in brain regions did not improve, while the SE level improved 24% with low-protein consumption. Blood-branched chain amino acids (LEU, ILE, and VAL in sera (SE)) were 362-434 μM, consistent with human values considered within control. Nonetheless, numerous amino acids in brain regions remained abnormal despite protein restriction, including glutamine (GLN), aspartate (ASP), glutamate (GLU), gamma-aminobutyric acid (GABA), asparagine (ASN), citrulline (CIT) and serine (SER). To assess the specificity of these anomalies, we piloted preliminary studies in hyperphenylalaninemic mice, modeling another large neutral aminoacidopathy. Employing an identical dietary regimen, we found remarkably consistent abnormalities in GLN, ASP, and GLU. CONCLUSIONS: Our results suggest that blood amino acid analysis may be a poor surrogate for assessing the outcomes of protein restriction in the large neutral amino acidopathies, and further indicate that chronic neurotransmitter disruptions (GLU, GABA, ASP) may contribute to long-term neurocognitive dysfunction in these disorders

Altered protein phosphatase 2A methylation and Tau phosphorylation in the young and aged brain of methylenetetrahydrofolate reductase (MTHFR) deficient mice

Common functional polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, a key enzyme in folate and homocysteine metabolism, influence risk for a variety of complex disorders, including developmental, vascular, and neurological diseases. MTHFR deficiency is associated with elevation of homocysteine levels and alterations in the methylation cycle. Here, using young and aged Mthfr knockout mouse models, we show that mild MTHFR deficiency can lead to brain-region specific impairment of the methylation of Ser/Thr protein phosphatase 2A (PP2A). Relative to wild-type controls, decreased expression levels of PP2A and leucine carboxyl methyltransferase (LCMT1) were primarily observed in the hippocampus and cerebellum, and to a lesser extent in the cortex of young null Mthfr-/-and aged heterozygous Mthfr+/- mice. A marked down regulation of LCMT1 correlated with the loss of PP2A/Ba holoenzymes. Dietary folate deficiency significantly decreased LCMT1, methylated PP2A and PP2A/Ba levels in all brain regions examined from aged Mthfr+/+ mice, and further exacerbated the regional effects of MTHFR deficiency in aged Mthfr+/-mice. In turn, the down regulation of PP2A/Ba was associated with enhanced phosphorylation of Tau, a neuropathological hallmark of Alzheimer's disease (AD). Our findings identify hypomethylation of PP2A enzymes, which are major CNS phosphatases, as a novel mechanism by which MTHFR deficiency and Mthfr gene-diet interactions could lead to disruption of neuronal homeostasis, and increase the risk for a variety of neuropsychiatric disorders, including age-related diseases like sporadic AD. © 2014 Sontag, Wasek, Taleski, Smith, Arning, Sontag and Bottiglieri

Enhanced susceptibility to arterial thrombosis in a murine model of hyperhomocysteinemia

Hyperhomocysteinemia is a risk factor for thrombosis, but the mechanisms are not well defined. We tested the hypothesis that hyperhomocysteinemia accelerates arterial thrombosis in mice. Mice heterozygous for a targeted disruption of the cystathionine β-synthase gene (Cbs+/–) and wild-type littermates (Cbs+/+) were fed either a control diet or a high methionine/low folate (HM/LF) diet for 6 to 8 months to produce graded hyperhomocysteinemia. The time to occlusion of the carotid artery after photochemical injury was shortened by more than 50% in Cbs+/+ or Cbs+/– mice fed the HM/LF diet (P < .001 versus control diet). Carotid artery thrombosis was not accelerated in mice deficient in endothelial nitric oxide synthase (Nos3), which suggests that decreased endothelium-derived nitric oxide is not a sufficient mechanism for enhancement of thrombosis. Cbs+/+ and Cbs+/– mice fed the HM/LF diet had elevated levels of reactive oxygen species in the carotid artery, increased aortic expression of the NADPH oxidase catalytic subunit, Nox4, and decreased activation of anticoagulant protein C in the aorta (P < .05 versus control diet). We conclude that hyperhomocysteinemia enhances susceptibility to arterial thrombosis through a mechanism that is not caused by loss of endothelium-derived nitric oxide but may involve oxidative stress and impairment of the protein C anticoagulant pathway