Urinary Excretion Of Amino Acids Research Articles

SLC6A19 inhibition facilitates urinary neutral amino acid excretion and lowers plasma phenylalanine.

BACKGROUNDThe toxic accumulation of phenylalanine (Phe) in the brain underlies the neurological presentation of phenylketonuria (PKU). Solute carrier family 6 member 19 (SLC6A19) is the major transporter responsible for the (re)absorption of Phe in the kidney and intestine. Here, we describe the characterization of the first small molecule SLC6A19 inhibitor to enter clinical development for the treatment of PKU.METHODSC57Bl/6J WT and Pahenu2 mice were dosed with an inhibitor of SLC6A19 to investigate the effects on urinary amino acids and plasma Phe. In a phase 1 study, healthy human volunteers were dosed with JNT-517, an investigational oral inhibitor of SLC6A19. The primary objective of the study was safety. Secondary objectives included pharmacokinetic and pharmacodynamic studies.RESULTSInhibition of SLC6A19 increased the urinary excretion of Phe in a mouse model of PKU, thereby reducing plasma Phe levels. JNT-517, an investigational oral SLC6A19 inhibitor, was found to be safe and well tolerated and increased the urinary excretion of Phe in a phase 1 healthy volunteer study.CONCLUSIONSThese data indicate that pharmacological inhibition of SLC6A19 presents a promising approach to lower toxic elevated levels of amino acids found in PKU and related amino acid metabolism disorders by facilitating their renal elimination.TRIAL REGISTRATIONAustralian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12622001222730.FUNDINGThe studies in this paper were funded by Jnana Therapeutics.

A-317 Development of a patient-focused volumetric absorptive microsampling strategy to assess urinary amino acid excretion

Abstract Background Biochemical determinations of urinary amino acid excretion patterns can diagnose specific inborn errors of metabolism (IEM). Clinical management of these genetic metabolic patients may require frequent urine amino acid tests. A simplified process for transporting home collected urine specimens would benefit the IEM community. Volumetric absorptive microsampling (VAMS) is an emergent alternative sampling technique for the collection of dried biological specimens. We describe the development and preliminary validation results of a VAMS strategy for the analysis of creatinine and amino acids (N=22) from microsampled dried urine. Methods Urine creatinine and amino acids were respectively measured in a clinical laboratory setting using established assays on a CobasPro (Roche) and a MassTrak ultra-performance liquid chromatography (UPLC) amino acid analysis (AAA) solution (Waters). Two 30 µL VAMS tips from a Mitra device (Neoteryx) were used to sample each random urine specimen. An ultrasonication-based solvent extraction procedure was optimized to extract the amino acids and creatinine from the VAMS tips. Solvent extracts were subsequently dried by centrifugal evaporation. Extract from one tip was re-dissolved in water and tested for creatinine using an enzymatic method. The other extract was re-dissolved in 0.02 N sodium hydroxide and tested according to the MassTrak AAA procedure, which deploys pre-column AccQTag derivatization with reversed-phase UPLC on a C18 column (2.1 × 150 mm; 1.7 µm) and UV detection at 260 nm. Accuracy, within-batch precision and short-term stability of the optimized VAMS protocol were determined. Results Extraction solvent with a 60:40 (v/v) water:methanol mixture provided the highest average amino acid recovery. This extraction solvent produced higher average amino acid recoveries at pH 11 (89±13%), than pH 3 (82±10%) or pH 7 (72±11%). Creatinine measured from the VAMS tips (N=44) had a consistent negative bias of 20% relative to neat urine (R=0.9905, slope=0.802, intercept=0.02). The creatinine corrected urine amino acid results from the Mitra device were corrected for this observed concentration bias. The accuracy of the amino acid results derived from the VAMS tip vs neat urine was 104 ± 14%. The average within-batch precision (CV%) of the amino acids was 9.8% (range=6.7% (cystine) to 17.6% (arginine)) and 6.2% for creatinine. The average 1 week storage stability at ambient temperature was 91% (range=73% (ornithine) to 107% (glycine)) for the amino acids and 107% for creatinine. The devised VAMS strategy was applied to the analysis of microsampled dried urine from a patient with cystinuria (OMIM no. 220100). Marked elevations in arginine, cystine, lysine and ornithine were respectively observed and are consistent with the biochemical diagnosis of the patient. Conclusions Creatinine corrected amino acid results from the devised VAMS strategy exhibit good precision and accuracy when compared to tradition analyses of neat urine. The potential use of microsampled dried urine for the diagnosis and monitoring of selected IEM has been demonstrated. The analytical and clinical performance of this VAMS protocol must be further validated, including the use of microsampled dried urine from home specimen collections.

Interactive Effects of Empagliflozin and Hyperglycemia on Urinary Amino Acids in Individuals With Type 1 Diabetes.

Optimizing energy utilization in the kidney is critical for normal kidney function. Here, we investigate the effect of hyperglycemia and sodium-glucose cotransporter-2 (SGLT2) inhibition on urinary amino acid excretion in individuals with type 1 diabetes (T1D). The open-label ATIRMA trial assessed the impact of 8 weeks of oral empagliflozin 25 mg/day in 40 normotensive, normoalbuminuric young adults with T1D. A consecutive two-day assessment of clamped euglycemia and hyperglycemia was evaluated at baseline and post-treatment visit. Principal component analysis was performed on urinary amino acids grouped into representative metabolic pathways using MetaboAnalyst. At baseline, acute hyperglycemia was associated with changes in 25 of the 33 urinary amino acids or their metabolites. The most significant amino acid metabolites affected by acute hyperglycemia were 3-hydroxykynurenine, serotonin, glycyl-histidine, and nicotinic acid. The changes in amino acid metabolites were reflected by the induction of four biosynthetic pathways - aminoacyl-tRNA, valine, leucine and isoleucine, arginine, as well as phenylalanine, tyrosine, and tryptophan. Under acute hyperglycemia, empagliflozin significantly attenuated the increases to aminoacyl-tRNA biosynthesis and valine, leucine and isoleucine biosynthesis. Our findings using amino acid metabolomics indicate that hyperglycemia stimulates biosynthetic pathways in T1D. SGLT2 inhibition may attenuate the increase in biosynthetic pathways to optimize kidney energy metabolism.

Lysinuric protein intolerance presenting as pancytopenia and splenomegaly mimicking acute leukaemia: a case report

BackgroundLysinuric protein intolerance is a rare inherited metabolic disease due to autosomal recessive mutations of the SLC7A7 gene. The affected patients commonly present with protein-rich food intolerance, failure to thrive, hepatosplenomegaly, muscle hypotonia and lung involvement due to impaired intestinal absorption and excessive urinary excretion of dibasic amino acids. Presentation with splenomegaly and cytopenia without other features has not been reported. Here we report a Sri Lankan girl with lysinuric protein intolerance presenting with pancytopenia and splenomegaly mimicking acute leukaemia.Case presentationTwo years and six months old Sri Lankan girl presented with persistent pancytopenia following a viral illness. She was asymptomatic without vomiting, diarrhoea, abdominal pain or irritability. Physical examination revealed pallor and isolated firm splenomegaly of 2 cm. Growth parameters and other system examinations were normal. Full blood count revealed anaemia, leukopenia and thrombocytopenia. The blood picture showed a mixture of hypochromic microcytic and normochromic normocytic red cells with occasional pencil cells and macrocytes. Bone marrow examination was normal except for occasional megaloblasts; however, serum vitamin B12 and red blood cell folate were normal. The metabolic screen showed a high anion gap compensated metabolic acidosis, high lactate and ketosis. Genetic mutation analysis using whole exome sequencing revealed compound heterozygous variants of the SLC7A7 gene, confirming the diagnosis of lysinuric protein intolerance.ConclusionWe report a child with lysinuric protein intolerance presenting with pancytopenia and splenomegaly without other disease features. This case report adds to the heterogenic presentations of lysinuric protein intolerance, which is considered a multifaceted disease.

Long-term home parenteral nutrition and profile of amino acids in serum and their loss in urine.

Amino acids are an essential part of parenteral nutrition. This study aimed to determine the serum profile of amino acids and their loss in urine in patients with long-term home parenteral nutrition (HPN) during 12 h of infusion in comparison with similar parameters in the remaining 12 h as well as in healthy participants. We enrolled forty-five patients with long-term HPN for 6-75 (median, 33) months. The indication for HPN was short bowel syndrome secondary to radical resection of the small intestine following complications of Crohn's disease. HPN was administered via two-chamber all-in-one bags prepared in a hospital pharmacy overnight for 12 h each day. The average dose of amino acids, carbohydrates and fats administered was 1·5, 3·4 and 0·68 g/kg per d, respectively, at an infusion rate of 0·11, 0·28 and 0·06 g/kg per h, respectively. The levels of essential amino acids in the serum of the patients were not significantly different from those in healthy individuals; however, of the non-essential amino acids, cystine and glutamine levels were lower and glycine and ornithine levels were higher in the patients (P < 0·05). Excretion of amino acids in the urine during 12 h of infusion at an infusion rate of 0·11 g/kg per h was 301 mg, while it was 104 mg during the remaining 12 h (P < 0·0001). Our patients on long-term HPN had a normal serum profile of essential amino acids. The total urinary excretion of amino acids during 12 h of infusion accounted for only 0·34 % (0·23-0·46) of the administered dose.

Clinical features of pediatric renal glucosuria cases due to SLC5A2 gene variants

AbstractBackgroundFamilial renal glycosuria (FRG) is a rare renal tubular disorder characterized by a variable loss of glucose in the urine despite normal blood glucose levels, which is seen in a condition in which other tubular functions are preserved. In this study, the molecular and clinical characteristics of pediatric FRG cases due to SLC5A2 gene variants were defined.MethodsDemographic features, diagnostic tests, and molecular analyses of patients with a diagnosis of FRG cases due to SLC5A2 gene variants were retrospectively analyzed between 2016 and 2019.ResultsThe data of 16 patients who were clinically and genetically diagnosed with FRG in a 4‐year period were analyzed. Seven (44%) of the cases were female and 9 (56%) were male. The median age at diagnosis was 6 years old (2 months old to 17 years old). Neuromotor development was found to be appropriate for the age in each case. Systemic blood pressure was evaluated as normal. A homozygous pathogenic variant in the SLC5A2 gene was detected in 14 patients in the genetic examination. A heterozygous variant was detected in one patient. In the other patient, two different heterozygous pathological variants were found in the SLC5A2 gene.ConclusionsIt was revealed that growth and development were normal in children with glucosuria due to variations in the SCL5A2 gene. Renal function tests and urinary amino acid excretion were also within normal values. In our case series, the most common genetic variation in the SCL5A2 gene was the A219T (c.655G&gt;A) variant.

Urinary excretion of amino acids and their advanced glycation end-products (AGEs) in adult kidney transplant recipients with emphasis on lysine: furosine excretion is associated with cardiovascular and all-cause mortality

Arginine (Arg) and lysine (Lys) moieties of proteins undergo various post-translational modifications (PTM) including enzymatic NG- and Nε-methylation and non-enzymatic NG- and Nε-glycation. In a large cohort of stable kidney transplant recipients (KTR, n = 686), high plasma and low urinary concentrations of asymmetric dimethylarginine (ADMA), an abundant PTM metabolite of Arg, were associated with cardiovascular and all-cause mortality. Thus, the prediction of the same biomarker regarding mortality may depend on the biological sample. In another large cohort of stable KTR (n = 555), higher plasma concentrations of Nε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL), two advanced glycation end-products (AGEs) of Lys, were associated with higher cardiovascular mortality. Yet, the associations of urinary AGEs with mortality are unknown. In the present study, we measured 24 h urinary excretion of Lys, CML, and furosine in 630 KTR and 41 healthy kidney donors before and after donation. Our result indicate that lower urinary CML and lower furosine excretion rates are associated with higher mortality in KTR, thus resembling the associations of ADMA. Lower furosine excretion rates were also associated with higher cardiovascular mortality. The 24 h urinary excretion rate of amino acids and their metabolites decreased post-donation (varying as little as − 24% for CEL, and as much as − 62% for ADMA). For most amino acids, the excretion rate was lower in KTR than in donors pre-donation [except for S-(1-carboxyethyl)-l-cysteine (CEC) and NG-carboxyethylarginine (CEA)]. Simultaneous GC–MS measurement of free amino acids, their PTM metabolites and AGEs in urine is a non-invasive approach in kidney transplantation.

Profile of urinary amino acids and their post-translational modifications (PTM) including advanced glycation end-products (AGEs) of lysine, arginine and cysteine in lean and obese ZSF1 rats

Heart failure with preserved ejection fraction (HFpEF) is associated with high mortality and has an increasing prevalence associated with the demographic change and limited therapeutic options. Underlying mechanisms are largely elusive and need to be explored to identify specific biomarkers and new targets, which mirror disease progression and intervention success. Obese ZSF1 (O-ZSF1) rats are a useful animal model, as they spontaneously develop hypertension, hyperlipidemia and glucose intolerance and finally HFpEF. The urinary profile of amino acids and their metabolites of post-translational modifications (PTM), including the advanced glycation end-products (AGEs) of lysine, arginine and cysteine, are poorly investigated in HFpEF and ZSF1 rats. The aim of the present study was to characterize the status of free amino acids and their metabolites of PTM and glycation in lean ZSF1 (L-ZSF1) and O-ZSF1 rats in urine aiming to find possible effects of glucose on the excretion of native and modified amino acids. In the urine of twelve L-ZSF1 and twelve O-ZFS1 rats collected at the age of 20 weeks, we measured the concentration of native and modified amino acids by reliable previously validated stable-isotope dilution gas chromatography-mass spectrometry (GC–MS) approaches. Serum glucose was 1.39-fold higher in the O-ZSF1 rats, while urinary creatinine concentration was 2.5-fold lower in the O-ZSF1 rats. We observed many differences in urinary amino acids excretion between L-ZSF1 and O-ZSF1 rats. The creatinine-corrected homoarginine excretion was twofold lower in the O-ZSF1 rats. We also observed distinct associations between the concentrations of serum glucose and urinary amino acids including their PTM and AGE metabolites in the L-ZSF1 and O-ZSF1 rats. Our study shows that PTM metabolites and AGEs are consistently lower in the L-ZSF1 than in the O-ZSF1 rats. Serum malondialdehyde (MDA) concentration was higher in the O-ZSF1 rats. These results suggest that hyperglycemia, hyperlipidemia and elevated oxidative stress in the O-ZSF1 rats favor PTM methylation of arginine and lysine and the glycation of lysine and cysteine. The area under the receiver operation characteristic (ROC) curve values were 0.996 for serum glucose, 0.951 for urinary creatinine, 0.939 for serum MDA, 0.885 for Nε-carboxyethyl-lysine, 0.830 for carboxyethyl-cysteine, and 0.792 for monomethyl-lysine. Non-invasive measurement of methylation and glycation products of arginine, lysine and cysteine residues in proteins in urine of L-ZSF1 and O-ZSF1 rats may be useful in studying pathophysiology and pharmacology of HFpEF.

Kidney and vascular function in adult patients with hereditary fructose intolerance

Objective: Previous studies have shown that patients with hereditary fructose intolerance (HFI) are characterized by a greater intrahepatic triglyceride content, despite a fructose-restricted diet. The present study aimed to examine the long-term consequences of HFI on other aldolase-B-expressing organs, i.e. the kidney and vascular endothelium.Methods: Fifteen adult HFI patients were compared to healthy control individuals matched for age, sex and body mass index. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (cf-PWV) and endothelial function by peripheral arterial tonometry, skin laser doppler flowmetry and the endothelial function biomarkers soluble E-selectin [sE-selectin] and von Willebrand factor. Serum creatinine and cystatin C were measured to estimate the glomerular filtration rate (eGFR). Urinary glucose and amino acid excretion and the ratio of tubular maximum reabsorption of phosphate to GFR (TmP/GFR) were determined as measures of proximal tubular function. Results: Median systolic blood pressure was significantly higher in HFI patients (127 versus 122 mmHg, p = .045). Pulse pressure and cf-PWV did not differ between the groups (p = .37 and p = .49, respectively). Of all endothelial function markers, only sE-selectin was significantly higher in HFI patients (p = .004). eGFR was significantly higher in HFI patients than healthy controls (119 versus 104 ml/min/1.73m2, p = .001, respectively). All measurements of proximal tubular function did not differ significantly between the groups.Conclusions: Adult HFI patients treated with a fructose-restricted diet are characterized by a higher sE-selectin level and slightly higher systolic blood pressure, which in time could contribute to a greater cardiovascular risk. The exact cause and, hence, clinical consequences of the higher eGFR in HFI patients, deserves further study.

The Role of Protein and Free Amino Acids on Intake, Metabolism, and Gut Microbiome: A Comparison Between Breast-Fed and Formula-Fed Rhesus Monkey Infants.

Background: Compared to breast-fed (BF), formula-fed (FF) infants exhibit more rapid weight gain, a different fecal microbial profile, as well as elevated serum insulin, insulin growth factor 1 (IGF-1), and branched chain amino acids (BCAAs). Since infant formula contains more protein and lower free amino acids than breast milk, it is thought that protein and/or free amino acids may be key factors that explain phenotypic differences between BF and FF infants.Methods: Newborn rhesus monkeys (Macaca mulatta) were either exclusively BF or fed regular formula or reduced protein formula either supplemented or not with a mixture of amino acids. Longitudinal sampling and clinical evaluation were performed from birth to 16 weeks including anthropometric measurements, intake records, collection of blood for hematology, serum biochemistry, hormones, and metabolic profiling, collection of urine for metabolic profiling, and collection of feces for 16s rRNA fecal microbial community profiling.Results: Reducing protein in infant formula profoundly suppressed intake, lowered weight gain and improved the FF-specific metabolic phenotype in the first month of age. This time-dependent change paralleled an improvement in serum insulin. All lower protein FF groups showed reduced protein catabolism with lower levels of blood urea nitrogen (BUN), urea, ammonia, albumin, creatinine, as well as lower excretion of creatinine in urine compared to infants fed regular formula. Levels of fecal microbes (Bifidobacterium and Ruminococcus from the Ruminococcaceae family), that are known to have varying ability to utilize complex carbohydrates, also increased with protein reduction. Adding free amino acids to infant formula did not alter milk intake or fecal microbial composition, but did significantly increase urinary excretion of amino acids and nitrogen-containing metabolites. However, despite the lower protein intake, these infants still exhibited a distinct FF-specific metabolic phenotype characterized by accelerated weight gain, higher levels of insulin and C-peptide as well as elevated amino acids including BCAA, lysine, methionine, threonine and asparagine.Conclusions: Reducing protein and adding free amino acids to infant formula resulted in growth and metabolic performance of infants that were more similar to BF infants, but was insufficient to reverse the FF-specific accelerated growth and insulin-inducing high BCAA phenotype.

Urinary Excretion of Amino Acids in Children with Type 1 Diabetes

Urinary Excretion of Amino Acids in Children with Type 1 Diabetes

Plasma profile and urine excretion of amino acids in children with celiac disease on gluten-free diet after oligofructose-enriched inulin intervention: results of a randomised placebo-controlled pilot study

The circulating amino acid (AAs) concentrations are indicators of dietary protein intake and metabolic status. In celiac disease (CD), the AA imbalance is frequently observed. Prebiotics are found to alleviate nutrient deficiencies. Therefore, the aim of this study was to analyse the impact of oligrofructose-enriched inulin (Synergy 1), administered for 3 months as a gluten-free diet (GFD) supplement to children with CD, on the plasma and urine concentrations of AAs. CD children (N = 34) were randomised into two groups, receiving Synergy 1 (10 g/day) or placebo (maltodextrin) for 3 months. The AA profile and concentration was determined in plasma and urine before and after the dietary intervention by gas chromatography. 22 and 28 AAs were determined in plasma and urine samples, respectively. After the intervention, the plasma concentrations of several AAs (Ala, Pro, Asn, Glu, Tyr, Lys, His, Orn) increased significantly in both experimental groups, while Gln increased only in the Synergy 1 group. The urinary excretion of Asn, Lys and Aaa increased significantly in the Synergy 1 group, and the excretion of Asp and Met decreased (p < 0.05) in the placebo group. The Gln:Glu ratio in urine increased in both groups after the intervention. An increased urinary excretion of AAs observed in Synergy 1 group with a simultaneous increase in the content of circulating AAs could be attributed to higher absorption or intensified metabolism of AAs, and on the other hand further healing of the intestinal mucosa being the result of continuous treatment with GFD. Moreover, the observed changes in Glu concentration suggest that oligofructose-enriched inulin could improve the intestinal condition and permeability. To conclude, a prebiotic-supplemented GFD influences beneficially the overall AAs metabolism in CD children; however, further prospective cohort studies are needed to confirm the results obtained.

Differences in Urinary Amino Acid Patterns in Individuals with Different Types of Urological Tumor Urinary Amino Acid Patterns as Markers of Urological Tumors

Insufficient specificity and invasiveness of currently used diagnostic methods raises the need for new markers of urological tumors. The aim of this study was to find a link between the urinary excretion of amino acids and the presence of urological tumors. Using ion-exchange chromatography, we tested urine samples of patients with prostate cancer (n=30), urinary bladder cancer (n=28), renal cell carcinoma (n=16) and healthy volunteers (control group; n=21). In each category, we found a group of amino acids which differed in concentration compared to the control group. These differences were most significant in sarcosine in patients with prostate cancer; leucine, phenylalanine and arginine in those with bladder cancer; and sarcosine, glutamic acid, glycine, tyrosine and arginine in the those with renal cell carcinoma. Results of our research imply a possible connection between the occurrence of specific types of amino acids in the urine and the presence of urological tumors.

Decreased Glycaemia with Renal Failure in Diabetes Betides in Relation to the Change in Renal Glutamate Metabolism

A reduction in renal gluconeogenesis appears to be one cause for the drop in blood glucose concentration (BGC) accompanying decreased renal function in diabetes. However, it remains unclear as to how this drop in BGC is related to the changes in reabsorption of amino acids (AAs) that accompany decreased renal function. We therefore investigated the relationship between the drop in BGC accompanying decreased renal function in diabetes patients and changes in the reabsorption rates of AAs. Subjects and methods: Using 100 diabetes patients and 100 non-diabetics as subjects, we measured their blood AAs concentration and urinary AAs excretion, and calculated the AAs’ reabsorption rate. We then examined the relationship between the latter and the estimated glomerular filtration rate (eGFR) and HbA1c. Results: In diabetics, blood glutamate concentration and reabsorption rate of glutamate were reduced. The blood glutamine concentration was increased; however, the reabsorption of glutamine was unchanged. The reabsorption rates of some AAs, including glutamate, showed a positive correlation with eGFR. However, a reduced reabsorption rate of glutamate was the only independent risk factor for reduced eGFR. Moreover, only the reabsorption rate of glutamate correlated positively with HbA1c. Conclusions: In diabetes, glutamate reabsorption shows a decline that parallels decreased renal function: this reduction is related to a drop in BGC. The reduction in the reabsorption of glutamate appears to influence renal gluconeogenesis by reducing the gluconeogenesis-adjusting factor (malate-aspartate shuttle), not by reducing gluconeogenic substrates. Further studies are therefore needed to examine the role glutamate plays in renal gluconeogenesis.

Diverse characteristics of the urinary excretion of amino acids in humans and the use of amino acid supplementation to reduce fatigue and sub-health in adults

BackgroundThe excretion of amino acids in urine represents an important avenue for the loss of key nutrients. Some amino acids such as glycine and histidine are lost in higher abundance than others. These two amino acids perform important physiological functions and are required for the synthesis of key proteins such as haemoglobin and collagen.MethodsStage 1 of this study involved healthy subjects (n = 151) who provided first of the morning urine samples and completed symptom questionnaires. Urine was analysed for amino acid composition by gas chromatography. Stage 2 involved a subset of the initial cohort (n = 37) who completed a 30 day trial of an amino acid supplement and subsequent symptom profile evaluation.ResultsAnalyses of urinary amino acid profiles revealed that three groups could be objectively defined from the 151 participants using k-means clustering. The amino acid profiles were significantly different between each of the clusters (Wilks’ Lambda = 0.13, p < 0.0001). Cluster 1 had the highest loss of amino acids with histidine being the most abundant component. Cluster 2 had glycine present as the most abundant urinary amino acid and cluster 3 had equivalent abundances of glycine and histidine. Strong associations were observed between urinary proline concentrations and fatigue/pain scores (r = .56 to .83) for females in cluster 1, with several other differential sets of associations observed for the other clusters.ConclusionsDifferent phenotypic subsets exist in the population based on amino acid excretion characteristics found in urine. Provision of the supplement resulted in significant improvements in reported fatigue and sleep for 81% of the trial cohort with all females reporting improvements in fatigue.Trial registrationThe study was registered on the 18th April 2011 with the Australian New Zealand Clinical Trials Registry (ACTRN12611000403932).

The relationship between the renal reabsorption of cysteine and the lowered urinary pH in diabetics.

In diabetic patients, reduced urinary pH (UpH) is a predictive factor for cardiorenal-vascular disorders. Synthesis of glutathione, an anti-oxidative stress substance, is induced to counteract renal oxidative stress. UpH declines as glutamate is consumed, as does the synthesis of ammonia from glutamate. Glutathione is synthesized from glutamate and cysteine; however, in diabetes, the relationship between lowered UpH and the roles of renal amino acids is unknown. We, therefore, examined the relationship between amino-acid kinetics, UpH, and renal function. This cross-sectional study targeted 100 non-diabetic obese individuals (OG: obese group) and 100 diabetics (DG: diabetic group). We investigated their blood amino acids, urinary amino-acid excretion, the reabsorption rates of various amino acids, and their relationship with the UpH and estimated glomerular filtration rate (eGFR). The DG subjects showed higher blood cysteine concentration, urinary glutamate, and cysteine excretions than the OG subjects. Although the glutamate reabsorption rate declined in the DG subjects, that of cysteine increased due to the lowered eGFR. The DG subjects' urinary cysteine excretion correlated positively with UpH, making this urinary cysteine excretion the sole independent risk factor for lower UpH. In patients with diabetes, the reabsorbed amount of cysteine, not glutamate, regulates the amount of glutathione synthesis in the kidneys. The more an amount of cysteine reabsorption increases concurrently with a decline in eGFR, the more its urinary excretion decreases. Under these conditions, concurrently, the glutamate consumption then increases, resulting in decreased ammonia synthesis and UpH.

The Reduction in Urinary Glutamate Excretion Is Responsible for Lowering Urinary pH in Pink Urine Syndrome

We frequently encounter brownish-red, cloudy urine in some obese subjects, which occurs due to pink urine syndrome (PUS). PUS is a phenomenon in which uric acid precipitates into the urine due to reduced urinary pH (UpH). The mechanism underlying urinary acidification has not been elucidated so far. UpH level is adjusted by urinary excretion of ammonia synthesized from glutamate or glutamine, suggesting that renal synthesis of ammonia from glutamate or glutamine is decreased in PUS. However, this hypothesis has not been examined yet. We therefore examined the changes in the urinary excretion of these amino acids in PUS. One-hundred-fifty male students who had undergone a physical examination were enrolled. To determine the presence [PUS (+), n = 72] or absence [PUS (-), n = 78] of PUS, urinary amino acid excretion and UpH were evaluated. Independent risk factors of lower UpH were determined using multiple regression analyses. The PUS (+) subjects, who had lower UpH values than PUS (-) subjects, showed lower urinary excretion of glutamate and some other glucogenic amino acids. Thus, UpH correlated positively with the urinary excretion of glutamate in the PUS (+) subjects. A reduction in urinary glutamate but not in glutamine excretion proved to be an independent risk factor for reduced UpH. In conclusion, PUS appears to occur when a reduction in the synthesis of ammonia from glutamate causes a decrease in UpH. Our results showed that urinary glutamate excretion was reduced in PUS because renal glutamate was consumed by a reaction different from ammonia production.

Changes in urinary amino acids excretion in relationship with muscle activity markers over a professional cycling stage race: in search of fatigue markers

The aim of this study was to identify the relationship between metabolic effort, muscular damage/activity indices, and urinary amino acids profile over the course of a strenuous prolonged endurance activity, as a cycling stage race is, in order to identify possible fatigue markers. Nine professional cyclists belonging to a single team, competing in the Giro d'Italia cycling stage race, were anthropometrically characterized and sampled for blood and urine the day before the race started, and on days 12 and 23 of the race. Diet was kept the same over the race, and power output and energy expenditure were recorded. Sera were assayed for muscle markers (lactate dehydrogenase, aspartate aminotransferase, and creatine kinase activities, and blood urea nitrogen), and creatinine, all corrected for plasma volume changes. Urines were profiled for amino acid concentrations, normalized on creatinine excretion. Renal function, in terms of glomerular filtration rate, was monitored by MDRD equation corrected on body surface area. Creatine kinase activity and blood urea were increased during the race as did serum creatinine while kidney function remained stable. Among the amino acids, taurine, glycine, cysteine, leucine, carnosine, 1-methyl histidine, and 3-methyl histidine showed a net decreased, while homocysteine was increased. Taurine and the dipeptide carnosine (β-alanyl-L-histidine) were significantly correlated with the muscle activity markers and the indices of effort. In conclusion, the metabolic profile is modified strikingly due to the effort. Urinary taurine and carnosine seem useful tools to evaluate the muscle damage and possibly the fatigue status on a long-term basis.

Urinary Amino Acid Alterations in 3-Year-Old Children with Neurodevelopmental Effects due to Perinatal Dioxin Exposure in Vietnam: A Nested Case-Control Study for Neurobiomarker Discovery

In our previous study of 3-year-old children in a dioxin contamination hot spot in Vietnam, the high total dioxin toxic equivalent (TEQ-PCDDs/Fs)-exposed group during the perinatal period displayed lower Bayley III neurodevelopmental scores, whereas the high 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-exposed group displayed increased autistic traits. In autistic children, urinary amino acid profiles have revealed metabolic alterations in the amino acids that serve as neurotransmitters in the developing brain. Therefore, our present study aimed to investigate the use of alterations in urinary amino acid excretion as biomarkers of dioxin exposure-induced neurodevelopmental deficits in highly exposed 3-year-old children in Vietnam. A nested case-control study of urinary analyses was performed for 26 children who were selected from 111 3-year-old children whose perinatal dioxin exposure levels and neurodevelopmental status were examined in follow-up surveys conducted in a dioxin contaminated hot spot. We compared urinary amino acid levels between the following 4 groups: (1) a high TEQ-PCDDs/Fs and high TCDD-exposed group; (2) a high TEQ-PCDDs/Fs but low TCDD-exposed group; (3) a low TEQ-PCDDs/Fs exposed and poorly developed group; and (4) a low TEQ-PCDDs/Fs exposed and well-developed group. Urinary levels of histidine and tryptophan were significantly decreased in the high TEQ-PCDDs/Fs and high TCDD group, as well as in the high TEQ-PCDDs/Fs but low TCDD group, compared with the low TEQ-PCDDs/Fs and well-developed group. However, the ratio of histidine to glycine was significantly lower only in the high TEQ-PCDDs/Fs and high TCDD group. Furthermore, urinary histidine levels and the ratio of histidine to glycine were significantly correlated with neurodevelopmental scores, particularly for language and fine motor skills. These results indicate that urinary histidine is specifically associated with dioxin exposure-induced neurodevelopmental deficits, suggesting that urinary histidine may be a useful marker of dioxin-induced neurodevelopmental deficits and that histaminergic neurotransmission may be an important pathological contributor to dioxin-mediated neurotoxicity.

Chronic Hepatitis B with Fanconi’s Syndrome Triggered by Short-term Administration of Adefovir Dipivoxil

The patient was a 45-year-old man who had Down syndrome and hepatitis B virus (HBV) with a high virus load and the presence of hepatitis B e antigen. He had received lamivudine (100mg/day: per os) as nucleoside/ nucleotide analogues (NAs) from April 2005 to December 2012. Although the initial response of HBV DNA was favorable, a high level of viral breakthrough without hepatitis reactivation occurred after 16 -months of lamivudine administration. In December 2012, the therapy with lamivudine was substituted with adefovir dipi‐ voxil (ADV) and entecavir hydrate (ETV) after informed consent was obtained. Serum HBV DNA gradually decreased over 7 -months of this drug substitution; however, there was a gradual increase in the serum alkali‐ phosfatase (ALP) level without increase in the other hepatobiliary enzymes and nephrotoxicity. Since he was suspected as having drug-induced liver damage and nephropathy caused by NAs, ADV and ETV were adminis‐ tered every other day for 3 months, resulting in no improvement. The laboratory data was obtained in December 2013 as follows; peak 3 dominant in the ALP isoenzyme analysis, low levels of serum carcium, phosphorus and urinary acid, excessive urinary excretion of amino acid and increased level of serum creatinine. Thus, we sug‐ gested that he suffered from acquired Fanconi’s syndrome induced by ADV. Administration of ADV was then discontinued after 12 months of drug substitution and only ETV was prescribed. Six months after ADV discon‐ tinuation, some of the indicative markers of renal dysfunction, including Fanconi’s syndrome, were normalized and recovered to the same levels before the combined use of ADV and ETV. The patient had been treated with sodium valproate and carbamazepine for the unstable mental state and epilepsy before the lamivudine adminis‐ tration; however, the negative synergic action among these drugs and NAs was not evaluated sufficiently. Here, we report the earlier onset of Fanconi’s syndrome triggered by ADV, which is usually diagnosed after long-term ADV administration. We suggest that the adequate evaluation of renal function, including proximal tubular damage before administration of ADV and close observation from the early period during treatment with ADV, is required.