Integration of stool microbiota, proteome and amino acid profiles to discriminate patients with adenomas and colorectal cancer.

Background: Screening for colorectal cancer (CRC) reduces its mortality but has limited sensitivity and specificity. Aims We aimed to explore potential biomarker panels for CRC and adenoma detection and to gain insight into the interaction between gut microbiota and human metabolism in the presence of these lesions.

Methods: This multicenter case-control cohort was performed between February 2016 and November 2019.

The potential of fecal microbiota and amino acids to detect and monitor patients with adenoma.

The risk of recurrent dysplastic colonic lesions is increased following polypectomy. Yield of endoscopic surveillance after adenoma removal is low, while interval colorectal cancers occur. To longitudinally assess the dynamics of fecal microbiota and amino acids in the presence of adenomatous lesions and after their endoscopic removal.

In vitro modeling of experimental succinic semialdehyde dehydrogenase deficiency (SSADHD) using brain-derived neural stem cells.

We explored the utility of neural stem cells (NSCs) as an in vitro model for evaluating preclinical therapeutics in succinic semialdehyde dehydrogenase-deficient (SSADHD) mice. NSCs were obtained from aldh5a1+/+ and aldh5a1-/- mice (aldh5a1 = aldehyde dehydrogenase 5a1 = SSADH). Multiple parameters were evaluated including: (1) production of GHB (γ-hydroxybutyrate), the biochemical hallmark of SSADHD; (2) rescue from cell death with the dual mTOR (mechanistic target of rapamycin) inhibitor, XL-765, an agent previously shown to rescue aldh5a1-/- mice from premature lethality; (3) mitochondrial number, total reactive oxygen species, and mitochondrial superoxide production, all previously documented as abnormal in aldh5a1-/- mice; (4) total ATP levels and ATP consumption; and (5) selected gene expression profiles associated with epilepsy, a prominent feature in both experimental and human SSADHD.

Cyst Fluid From Cystic, Malignant Brain Tumors: A Reservoir of Nutrients, Including Growth Factor-Like Nutrients, for Tumor Cells.

Background: Brain tumors may have cysts, whose content of nutrients could influence tumor cell microenvironment and growth.

Objective: To measure nutrients in cyst fluid from glioblastoma multiforme (GBM) and metastatic brain tumors.

Methods: Quantification of nutrients in cyst fluid from 12 to 18 GBMs and 4 to 10 metastatic brain tumors.

A small molecule inhibitor of mutant IDH2 rescues cardiomyopathy in a D-2-hydroxyglutaric aciduria type II mouse model.

D-2-hydroxyglutaric aciduria (D2HGA) type II is a rare neurometabolic disorder caused by germline gain-of-function mutations in isocitrate dehydrogenase 2 (IDH2), resulting in accumulation of D-2-hydroxyglutarate (D2HG). Patients exhibit a wide spectrum of symptoms including cardiomyopathy, epilepsy, developmental delay and limited life span. Currently, there are no effective therapeutic interventions.

Plants Possess a Cyclic Mitochondrial Metabolic Pathway similar to the Mammalian Metabolic Repair Mechanism Involving Malate Dehydrogenase and l-2-Hydroxyglutarate Dehydrogenase.

Enzymatic side reactions can give rise to the formation of wasteful and toxic products that are removed by metabolite repair pathways. In this work, we identify and characterize a mitochondrial metabolic repair mechanism in Arabidopsis thaliana involving malate dehydrogenase (mMDH) and l-2-hydroxyglutarate dehydrogenase (l-2HGDH). We analyze the kinetic properties of both A.

Torin 1 partially corrects vigabatrin-induced mitochondrial increase in mouse.

Recent findings in mice with targeted deletion of the GABA-metabolic enzyme succinic semialdehyde dehydrogenase revealed a new role for supraphysiological GABA (4-aminobutyric acid) in the activation of the mechanistic target of rapamycin (mTOR) that results in disruption of endogenous mitophagy. Employing biochemical and electron microscopic methodology, we examined the hypothesis that similar outcomes would be observed during intervention with vigabatrin, whose antiepileptic capacity hinges on central nervous system GABA elevation. Vigabatrin intervention was associated with significantly enhanced mitochondrial numbers and areas in normal mice that could be selectively normalized with the rapalog and mechanistic target of rapamycin inhibitor, Torin 1.

Human pyrroline-5-carboxylate reductase (PYCR1) acts on Δ(1)-piperideine-6-carboxylate generating L-pipecolic acid.

We have conducted biochemical studies with commercial available pyrroline-5-carboxylate (P5C) reductase (PYCR1) to investigate whether this enzyme plays a role in L-lysine degradation. Our recent studies with antiquitin/ALDH7A1 deficient fibroblasts revealed an alternative genesis of L-pipecolic acid, and we then hypothesized that PYCR1 was responsible for the conversion of Δ(1)-piperideine-6-carboxylate (P6C) into pipecolic acid. We here present evidence that PYCR1 is indeed able to produce L-pipecolic acid from P6C preparations, and the observed K m for this conversion is of the same magnitude as the K m described for the conversion of P5C to L-proline by PYCR1.

Mutant IDH1 promotes leukemogenesis in vivo and can be specifically targeted in human AML.

Mutations in the metabolic enzymes isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) are frequently found in glioma, acute myeloid leukemia (AML), melanoma, thyroid cancer, and chondrosarcoma patients. Mutant IDH produces 2-hydroxyglutarate (2HG), which induces histone- and DNA-hypermethylation through inhibition of epigenetic regulators. We investigated the role of mutant IDH1 using the mouse transplantation assay.

Deficiency in SLC25A1, encoding the mitochondrial citrate carrier, causes combined D-2- and L-2-hydroxyglutaric aciduria.

The Krebs cycle is of fundamental importance for the generation of the energetic and molecular needs of both prokaryotic and eukaryotic cells. Both enantiomers of metabolite 2-hydroxyglutarate are directly linked to this pivotal biochemical pathway and are found elevated not only in several cancers, but also in different variants of the neurometabolic disease 2-hydroxyglutaric aciduria. Recently we showed that cancer-associated IDH2 germline mutations cause one variant of 2-hydroxyglutaric aciduria.

IDH1 R132H decreases proliferation of glioma cell lines in vitro and in vivo.

Objective: A high percentage of grade II and III gliomas have mutations in the gene encoding isocitrate dehydrogenase (IDH1). This mutation is always a heterozygous point mutation that affects the amino acid arginine at position 132 and results in loss of its native enzymatic activity and gain of alternative enzymatic activity (producing D-2-hydroxyglutarate). The objective of this study was to investigate the cellular effects of R132H mutations in IDH1.

Plant D-2-hydroxyglutarate dehydrogenase participates in the catabolism of lysine especially during senescence.

D-2-Hydroxyglutarate dehydrogenase (D-2HGDH) catalyzes the specific and efficient oxidation of D-2-hydroxyglutarate (D-2HG) to 2-oxoglutarate using FAD as a cofactor. In this work, we demonstrate that D-2HGDH localizes to plant mitochondria and that its expression increases gradually during developmental and dark-induced senescence in Arabidopsis thaliana, indicating an enhanced demand of respiration of alternative substrates through this enzymatic system under these conditions. Using loss-of-function mutants in D-2HGDH (d2hgdh1) and stable isotope dilution LC-MS/MS, we found that the D-isomer of 2HG accumulated in leaves of d2hgdh1 during both forms of carbon starvation.

Anserine inhibits carnosine degradation but in human serum carnosinase (CN1) is not correlated with histidine dipeptide concentration.

Background: We reported an association of a particular allele of the carnosinase (CNDP1 Mannheim) gene with reduced serum carnosinase (CN1) activity and absence of nephropathy in diabetic patients. Carnosine protects against the adverse effects of high glucose levels but serum carnosine concentration was generally low.

Methods: We measured the concentration of two further histidine dipeptides, anserine and homocarnosine, via HPLC.

The difference between rare and exceptionally rare: molecular characterization of ribose 5-phosphate isomerase deficiency.

Ribose 5-phosphate isomerase (RPI) deficiency is an enzymopathy of the pentose phosphate pathway. It manifests with progressive leukoencephalopathy and peripheral neuropathy and belongs, with one sole diagnosed case, to the rarest human disorders. The single patient was found compound heterozygous for a RPI frameshift and a missense (RPI(Ala61Val)) allele.

Hepatocyte transplantation (HTx) corrects selected neurometabolic abnormalities in murine intermediate maple syrup urine disease (iMSUD).

Skvorak et al. [1] demonstrated the therapeutic efficacy of HTx in a murine model of iMSUD, confirming significant metabolic improvement and survival. To determine the effect of HTx on extrahepatic organs, we examined the metabolic effects of HTx in brain from iMSUD animals.

Neurotransmitter alterations in embryonic succinate semialdehyde dehydrogenase (SSADH) deficiency suggest a heightened excitatory state during development.

Background: SSADH (aldehyde dehydrogenase 5a1 (Aldh5a1); gamma-hydroxybutyric (GHB) aciduria) deficiency is a defect of GABA degradation in which the neuromodulators GABA and GHB accumulate. The human phenotype is that of nonprogressive encephalopathy with prominent bilateral discoloration of the globi pallidi and variable seizures, the latter displayed prominently in Aldh5a1-/- mice with lethal convulsions. Metabolic studies in murine neural tissue have revealed elevated GABA [and its derivatives succinate semialdehyde (SSA), homocarnosine (HC), 4,5-dihydroxyhexanoic acid (DHHA) and guanidinobutyrate (GB)] and GHB [and its analogue D-2-hydroxyglutarate (D-2-HG)] at birth.

Sedoheptulokinase deficiency due to a 57-kb deletion in cystinosis patients causes urinary accumulation of sedoheptulose: elucidation of the CARKL gene.

The most common mutation in the nephropathic cystinosis (CTNS) gene is a homozygous 57-kb deletion that also includes an adjacent gene carbohydrate kinase-like (CARKL). The latter gene encodes a protein that is predicted to function as a carbohydrate kinase. Cystinosis patients with the common 57-kb deletion had strongly elevated urinary concentrations of sedoheptulose (28-451 mmol/mol creatinine; controls and other cystinosis patients <9) and erythritol (234-1110 mmol/mol creatinine; controls and other cystinosis patients <148).

Increased guanidino species in murine and human succinate semialdehyde dehydrogenase (SSADH) deficiency.

Mice with targeted deletion of the GABA-degradative enzyme succinate semialdehyde dehydrogenase (SSADH; Aldh5a1; OMIM 271,980) manifest globally elevated GABA and regionally decreased arginine in brain extracts. We examined the hypothesis that arginine-glycine amidinotransferase catalyzed the formation of guanidinobutyrate (GB) from increased GABA by quantifying guanidinoacetate (GA), guanidinopropionate (GP) and GB in brain extracts employing stable isotope dilution gas chromatographic-mass spectrometry. GA and GB were up to 4- and 22-fold elevated, respectively, in total and regional (cerebellum, hippocampus, cortex) brain extracts derived from SSADH(-/-) mice.

Metabolism of gamma-hydroxybutyrate to d-2-hydroxyglutarate in mammals: further evidence for d-2-hydroxyglutarate transhydrogenase.

gamma-Hydroxybutyratic acid (GHB), and its prodrugs 4-butyrolactone and 1,4-butanediol, represent expanding drugs of abuse, although GHB is also used therapeutically to treat narcolepsy and alcoholism. Thus, the pathway by which GHB is metabolized is of importance. The goal of the current study was to examine GHB metabolism in mice with targeted ablation of the GABA degradative enzyme succinic semialdehyde dehydrogenase (SSADH(-/-) mice), in whom GHB persistently accumulates, and in baboons intragastrically administered with GHB immediately and persistently.

A novel, quantitative assay for homocarnosine in cerebrospinal fluid using stable-isotope dilution liquid chromatography-tandem mass spectrometry.

We describe a rapid and sensitive method for the quantification of homocarnosine in physiological fluids, with particular emphasis on cerebrospinal fluid (CSF). Homocarnosine was quantified as the butyl derivative, with (2)H(2)-l-homocarnosine as internal standard. Following deproteinization of CSF samples, supernatants were evaporated to dryness and derivatized with 10% 6M HCl in butanol.

The transmethylation cycle in the brain of Alzheimer patients.

Homocysteine accumulation, frequently observed in plasma of AD patients, may be a sign of a reduced activity of the brain methionine-homocysteine transmethylation cycle. S-Adenosylmethionine (SAM) is the main methyl donor in several transmethylation reactions. The demethylated product of SAM, S-adenosylhomocysteine (SAH), is hydrolyzed to yield homocysteine, which can be remethylated to methionine by transfer of a methyl group of 5-methyltetrahydrofolate (5-MTHF).

Intracellular S-adenosylhomocysteine increased levels are associated with DNA hypomethylation in HUVEC.

Hyperhomocysteinemia is a risk factor for atherosclerosis and vascular disease; however, the mechanism underlying this association remains poorly understood. Increased levels of intracellular S-adenosylhomocysteine (AdoHcy), secondary to homocysteine-mediated reversal of the AdoHcy hydrolase reaction, have been associated with reduced DNA methylation patterns and pointed as responsible for the hyperhomocysteinemia-related endothelial dysfunction. Methylation is an epigenetic feature of genomic DNA, which leads to alterations in gene expression.

Measurement of urinary D- and L-2-hydroxyglutarate enantiomers by stable-isotope-dilution liquid chromatography-tandem mass spectrometry after derivatization with diacetyl-L-tartaric anhydride.

Background: The differential diagnosis of D-2-hydroxyglutaric aciduria (D-2-HGA), L-2-hydroxyglutaric aciduria (L-2-HGA), and the combined D/L-2-hydroxyglutaric aciduria (D/L-2-HGA) can be accomplished only by the measurement of the corresponding 2-hydroxyglutarate (2-HG). Available methods for the determination of D- and L-2-HG in urine are either time-consuming and expensive or have not been extensively validated. We aimed to develop a method for their rapid and sensitive measurement.

Liver-directed adenoviral gene transfer in murine succinate semialdehyde dehydrogenase deficiency.

Murine succinate semialdehyde dehydrogenase (SSADH) deficiency (OMIM 271980; EC 1.2.1.