Blood Amino Acid Analysis Research Articles

Analysis of MTHFR gene variants in fifteen children with hyperhomocysteinemia

The clinical manifestations, biochemical and metabolic data, genetic variations and treatment data of children with MTHFR gene variant induced hyperhomocysteinemia admitted to Hangzhou Children's Hospital and Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from November 2015 to September 2021 were analysed retrospectively. A total of 15 pediatric patients were included, including 10 males and 5 females, with onset ages ranging from 6 days to 18 years old and confirmed ages ranging from 40 days to 18 years old. One confirmed case was detected through neonatal screening, and the remaining 14 cases were all diagnosed through genetic diagnosis after onset. The main clinical manifestations were feeding difficulties, hypotonia, epilepsy, developmental delay. All patients had elevated levels of blood homocysteine, with blood homocysteine levels before and after treatment being (151.46±57.44) μmol/L and (69.96±32.88) μmol/L, significantly decreased after treatment compared with before treatment, with a statistically significant difference (P<0.001). The blood methionine level before the treatment was 9.40 (6.20, 11.96) μmol/L, normal or slightly decreased compared to the reference range. The methionine level returned to normal after treatment. A total of 19 MTHFR gene variants were detected, with 6 being unreported variants and 13 being known variants. c.1316C>T (p.L439P) was the most common variant(16.6%,5/30). All the patients had varied neurological damages, with 7 patients improved after metabolic therapy by carnitine and folinic acid, 8 patients experiencing developmental delay, and 1 patient experiencing frequent epilepsy. The clinical manifestations of MTHFR gene variation-related hyperhomocysteinemia are complex and variable. Early-onset and homozygous variants often have a poor prognosis. Blood homocysteine, blood amino acid analysis, serum total homocysteine assay and gene testing are helpful for early diagnosis.

Clinical characteristics and CBS gene analysis of 13 cases with classic homocystinuria

Objective: To analyze the clinical features and CBS gene variants of 13 patients with classic homocystinuria, and the strategies of individual treatment and prevention were explored. Methods: The general information, clinical manifestations, laboratory tests, cranial images, CBS gene variants, diagnosis and therapeutic strategies of 13 patients with classic homocystinuria admitted to the Department of Pediatrics of Children's Hospital Affiliated to Zhengzhou University and Peking University First Hospital from November 2013 to June 2021 were analyzed retrospectively. Results: There were 13 patients diagnosed at the age of 10 days to 14 years, 6 were male and 7 were female. There were 3 patients detected by newborn screening and received treatment at the asymptomatic stage. There were 10 patients clinically diagnosed at the age of 5 to 14 years. Their symptoms appeared at age of 1 to 6 years. The major clinical manifestations were marfanoid features, lens dislocation and (or) myopia, developmental delay, osteoporosis, and cardiovascular diseases. Brain magnetic resonance imaging showed asymmetric infarcts in 4 patients and hypomyelination in 1 case. Increased blood methionine, plasma total homocysteine and urinary total homocysteine with normal urinary methylmalonic acid were found in 13 patients. The biochemical features were consistent with classic homocystinuria. Totally 18 variants were identified in CBS gene of 13 patients, 10 variants were novel and 8 were reported. only 1 patient was partially responsive to vitamin B6 treatment, while 12 cases were non-responsive. They were mainly treated with low methionine diet and betaine supplement. Three vitamin B6 non-responsive cases received liver transplantation at age of 3, 8 and 8 years, respectively. Their blood methionine and total homocysteine returned to normal within a week after liver transplantation. One patient died. Prenatal diagnosis was performed for a fetus when the mother was pregnant again. Two pathogenic CBS gene variants were identified from the amniocytes as same as the proband. Conclusions: The clinical manifestations of classic homocystinuria are complex and variable. Blood amino acid analysis, serum or urine total homocysteine assay and gene analysis are critical for its diagnosis. There were 10 novel CBS gene varients were identified expanding the CBS gene varient spectrum. Liver transplantation is an effective treatment. Prenatal diagnosis is important to prevent classic homocysteinuria.

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

BackgroundConventional 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.MethodsTo 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.ResultsLEU 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.ConclusionsOur 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.

Ornithine ingestion improved sleep disturbances but was not associated with correction of blood tryptophan ratio in Japanese Antarctica expedition members during summer

Members of expeditions to Antarctica may show changes in biological and physiological parameters involved in lipid, glucose, and thyroid hormone metabolism as they adapt to the environment; however, alterations in amino acid (AA) levels and sleep among expedition members in Antarctica have yet to be fully elucidated. We hypothesized that there would be alterations of blood AA levels, and ornithine (Orn) ingestion would affect biological parameters and sleep in Japanese expedition members during the summer in Antarctica. Japanese Antarctica Research Expedition members (22 people) who stayed in Antarctica for 3 months from December 2010 were examined, and a randomized double-blind study of Orn ingestion (400 mg/d) for 4 weeks was performed. Sleep conditions were evaluated subjectively by the Oguri-Shirakawa-Azumi (brief version) questionnaire. The blood of Japanese Antarctica Research Expedition members in Antarctica showed higher creatine kinase, lactate dehydrogenase, and ammonia levels than that in Japan. On blood AA analysis, aspartate, Orn, and serine were significantly higher, and alanine and tryptophan (Trp) were significantly lower in Antarctica than in Japan. The Trp ratio, the value of Trp divided by the sum of phenylalanine, tyrosine, and branched-chain AAs, was significantly lower in Antarctica than in Japan. Although sleep deteriorated during the stay in Antarctica, Orn ingestion, to some extent, improved sleep compared with the placebo group in Antarctica, suggesting that Orn is effective for people with heavy physical workloads in places such as Antarctica.

Rapid and quantitative blood amino acid analysis by chemical ionization mass spectrometry.

A quantitative analysis of amino acids in microsamples of dried blood spots by chemical ionization mass spectrometry has been developed. Isotope ratio determination was used as the quantitating technique via multiple labelled internal standards. This procedure yields excellent precision and accuracy as demonstrated by the analysis of known amino acid mixtures and of phenylalanine in the blood from newborns.

Removal of glutathione interference in blood amino acid analysis

Whole blood amino acid analysis, which is necessary to determine the net transfer of free amino acids to an organ, is hampered by the presence of high concentrations of glutathione in the erythrocyte. Reduced and oxidized glutathione interfere with the accurate measurement of alanine, glycine, and aspartate during ion exchange chromatography. Oxidation with performic acid provides a simple and expedient method of removing interfering glutathione peaks from the blood sample during analysis. This technique permits the precise quantitation of the majority of amino acids (including alanine and glycine) commonly measured in blood samples.

Neurosecretion in Rhodnius prolixus1 and the Problem of Endocrine Control of Reproduction

In the neurosecretory system of Rhodnius prolixus Stal, two groups of neurosccretory cells are seen in the Pars medialis, each of 12 A-cells (A1 and A2) and 4–5 B-cells. The neurosecretion (NSC) is channeled down to the corpora cardiaca. There are two modes of release of NSC: part of the material is released into the general blood circulation from these glands, and part of it is directly supplied to the target tissues via the nerve arising from the posterior end of the cardiaca and running along the ventral surface of the aorta. Ablation, autoradiography, and histochemical examination of the neurosecretory cells revealed that A-cells produce little material and have a negligible role during re-production. Of the two substypes, A2-cells produce more hormones. Autoradiography and histochemical examination of AF- and PAVB-positive haemocytes indicated that their stainable material is not a synthesized product nor is it metachromasia. Blood amino-acid analysis shows that cystine is present only in traces. It is suggested that the neurosecretory system of Rhodnius has only a subsidiary function during reproduction and that the insect is mostly dependent for its hormonal requirement on its host (rabbit). This material is supplied during the blood meal and is then stored in those haemocytes which are positive to aldehyde fuchsin (AF) and performance acid victoria blue (PAVB).

Results of a screening method for free amino acids: I. Whole blood

o1. The results of large population screening for inborn errors of amino acid metabolism using a simple paper chromatographic technique for whole blood amino acid analysis are given.2. This method for whole blood amino acid analysis has proven to be rapid, economical, and accurate.3. This method can be used for periodic evaluation of patients on dietotherapy as well as for the detection of amino acid disorders.4. Disorders originally detected by this method include homocystinuria,ornithinemia, maple syrup urine disease, transient methionine elevation, hyperaminoacidemia and tyrosinemia