Non-invasive Characterization of Glycosuria and Identification of Biomarkers in Diabetic Urine Using Fluorescence Spectroscopy and Machine Learning Algorithm

The current study presents a steadfast, simple, and efficient approach for the non-invasive determination of glycosuria of diabetes mellitus using fluorescence spectroscopy. A Xenon arc lamp emitting light in the range of 200-950 nm was used as an excitation source for recording the fluorescent spectra from the urine samples. A consistent fluorescence emission peak of glucose at 450 nm was found in all samples for an excitation wavelength of 370 nm. For confirmation and comparison, the fluorescence spectra of non-diabetic (healthy controls) were also acquired in the same spectral range. It was found that fluorescence emission intensity at 450 nm increases with increasing glucose concentration in urine. In addition, optimized synchronous fluorescence emission at 357 nm was used for simultaneously determining a potential diabetes biomarker, Tryptophan (Trp) in urine. It was also found that the level of tryptophan decreases with the increase in urinary glucose concentration. The quantitative estimation of urinary glucose can be demonstrated based on the intensity of emission light carried by fluorescence light. Moreover, the dissimilarities were further emphasized using the hierarchical cluster analysis (HCA) algorithm. HCA gives an obvious separation in terms of dendrogram between the two data sets based on characteristic peaks acquired from their fluorescence emission signatures. These results recommend that urinary glucose and tryptophan fluorescence emission can be used as potential biomarkers for the non-invasive analysis of diabetes.

Metabolomic Profiling of Human Urine Samples Using LC-TIMS-QTOF Mass Spectrometry

The identification of metabolites in biological samples is challenging due to their chemical and structural diversity. Ion mobility spectrometry (IMS) separates ionized molecules based on their mobility in a carrier buffer gas giving information about the ionic shape by measuring the rotationally averaged collision cross-section (CCS) value. This orthogonal descriptor, in combination with the m/z, isotopic pattern distribution, and MS/MS spectrum, has the potential to improve the identification of molecular molecules in complex mixtures. Urine metabolomics can reveal metabolic differences, which arise as a result of a specific disease or in response to therapeutic intervention. It is, however, complicated by the presence of metabolic breakdown products derived from a wide range of lifestyle and diet-related byproducts, many of which are poorly characterized. In this study, we explore the use of trapped ion mobility spectrometry (TIMS) via LC parallel accumulation with serial fragmentation (PASEF) for urine metabolomics. A total of 362 urine metabolites were characterized from 80 urine samples collected from healthy volunteers using untargeted metabolomics employing HILIC and RP chromatography. Additionally, three analytes (Trp, Phe, and Tyr) were selected for targeted quantification. Both the untargeted and targeted data was highly reproducible and reported CCS measurements for identified metabolites were robust in the presence of the urine matrix. A comparison of CCS values among different laboratories was also conducted, showing less than 1.3% ΔCCS values across different platforms. This is the first report of a human urine metabolite database compiled with CCS values experimentally acquired using an LC-PASEF TIMS-qTOF platform.

Strong Dependence between Tryptophan-Related Fluorescence of Urine and Malignant Melanoma

Urine autofluorescence at 295 nm is significantly higher in patients with malignant melanoma at each clinical stage compared to the healthy group. The largest difference is in the early-stages and without metastases. With increasing stage, the autofluorescence at 295 nm decreases. There is also a significant negative correlation between autofluorescence and Clark classification. Based on our results, it is assumed that the way malignant melanoma grows also affects urinary autofluorescence.

Liquid chromatography-mass spectrometry untargeted metabolomics reveals increased levels of tryptophan indole metabolites in urine of metabolic syndrome patients

Metabolic syndrome (MetS) is a multifactor condition predisposing for diabetes, cardiovascular diseases and other degenerative disorders. Although several diagnostic criteria have been established, none of them is specific and there is a call for better pathophysiological explanation of MetS and for the discovery of molecular biomarkers. Phenotype characterization at metabolome level might be useful for both purposes. To this end, our aim was to perform comparative untargeted metabolomics of urines from MetS patients and from the control group. The study participants included 52 diagnosticated and 50 healthy individuals from Leon city in central Mexico; 23 anthropometric and clinical parameters were measured and submitted to Principal Component Analysis (PCA). The obtained PCA model allowed us for selection of 11 MetS patients and 13 control subjects, correspondingly representative for each of the two groups (clearly separated in PCA). The first morning urines from these subjects were ambulatory collected and, after methanol extraction and acidification, were submitted to capillary liquid chromatography-high resolution mass spectrometry (LC-HRMS). The obtained data were analyzed on MetaboScape® platform (Bruker Daltonics). Specifically, t-test applied to LC-HRMS data revealed several ions presenting at least 3-fold higher intensities in MetS with respect to the control samples (p < 0.05). Data analysis and complementary experiments yielded the identification of the following metabolites: indole-3-acetic acid, indole-3-acetic acid-O-glucuronide, N-(indol-3-ylacetyl) glutamine, indole-3-carbaldehyde and hydroxyhexanoycarnitine. Additionally, indole-3-carboxylic acid was annotated with 2.13-fold higher abundance in MetS patients. To assess the contribution of individual metabolites in the difference between two groups of subjects, partial least square discriminant analysis was performed for LC-HRMS data and the obtained values of variable importance in projection (VIP), confirmed the association of six above mentioned compounds with MetS. Overall, this study provides direct evidence on the disturbed catabolism of tryptophan in metabolic syndrome.

Urine 6-Bromotryptophan: Associations with Genetic Variants and Incident End-Stage Kidney Disease

Higher serum 6-bromotryptophan has been associated with lower risk of chronic kidney disease (CKD) progression, implicating mechanisms beyond renal clearance. We studied genetic determinants of urine 6-bromotryptophan and its association with CKD risk factors and incident end-stage kidney disease (ESKD) in 4,843 participants of the German Chronic Kidney Disease (GCKD) study. 6-bromotryptophan was measured from urine samples using mass spectrometry. Patients with higher levels of urine 6-bromotryptophan had higher baseline estimated glomerular filtration rate (eGFR, p < 0.001). A genome-wide association study of urine 6-bromotryptophan identified two significant loci possibly related to its tubular reabsorption, SLC6A19, and its production, ERO1A, which was also associated with serum 6-bromotryptophan in an independent study. The association between urine 6-bromotryptophan and time to ESKD was assessed using Cox regression. There were 216 ESKD events after four years of follow-up. Compared with patients with undetectable levels, higher 6-bromotryptophan levels were associated with lower risk of ESKD in models unadjusted and adjusted for ESKD risk factors other than eGFR ( Collapse

Key Words

• prognostic markers
• kidney diseases
• biomarkers
• epidemiology
• genetics research
• outcomes research
• risk factors

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MESH Headings

• Amino Acid Transport Systems, Neutral/genetics
• Female
• Genetic Predisposition to Disease/genetics
• Genetic Variation/genetics
• Glomerular Filtration Rate/genetics
• Humans
• Kidney Failure, Chronic/epidemiology
• Kidney Failure, Chronic/genetics
• Kidney Failure, Chronic/urine
• Male
• Membrane Glycoproteins/genetics
• Middle Aged
• Oxidoreductases/genetics
• Proportional Hazards Models
• Risk Factors
• Tryptophan/analogs & derivatives
• Tryptophan/urine

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Grants

• R21 DK112087 NIDDK NIH HHS
• UL1 RR025005 NCRR NIH HHS
• R01 HL086694 NHLBI NIH HHS
• U01 HG004402 NHGRI NIH HHS
• HHSN268201700002C NHLBI NIH HHS
• HHSN268201700001I NHLBI NIH HHS
• HHSN268201700004I NHLBI NIH HHS
• HHSN268201700004C NHLBI NIH HHS
• R01 HL087641 NHLBI NIH HHS
• HHSN268201700003I NHLBI NIH HHS
• HHSN268201700005C NHLBI NIH HHS
• HHSN268201700001C NHLBI NIH HHS
• HHSN268201700003C NHLBI NIH HHS
• HHSN268201700002I NHLBI NIH HHS
• HHSN268201700005I NHLBI NIH HHS

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Affiliation(s)

Peggy Sekula Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
Adrienne Tin Division of Nephrology, Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA The Memory Impairment and Neurodegenerative Dementia Center, University of Mississippi Medical Center, Jackson, MS, USA
Ulla T Schultheiss Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany Division of Nephrology, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
Seema Baid-Agrawal Department of Nephrology and Transplant Center, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
Robert P Mohney Metabolon Inc., Durham, NC, USA
Inga Steinbrenner Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
Bing Yu School of Public Health, The University of Texas Health Science Center at Houston, Houston, USA
Shengyuan Luo Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, MD, USA
Eric Boerwinkle School of Public Health, The University of Texas Health Science Center at Houston, Houston, USA
Kai-Uwe Eckardt Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
Josef Coresh Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, MD, USA
Morgan E Grams Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, MD, USA Division of Nephrology, Johns Hopkins School of Medicine, Baltimore, MD, USA
Anna Kӧttgen Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.

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Urine metabolomic analysis for monitoring internal load in professional football players

INTRODUCTION

The design of training programs for football players is not straightforward due to intra- and inter-individual variability that leads to different physiological responses under similar training loads.

OBJECTIVE

To study the association between the external load, defined by variables obtained using electronic performance tracking systems (EPTS), and the urinary metabolome as a surrogate of the metabolic adaptation to training.

METHODS

Urine metabolic and EPTS data from 80 professional football players collected in an observational longitudinal study were analyzed by ultra-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry and assessed by partial least squares (PLS) regression.

RESULTS

PLS models identified steroid hormone metabolites, hypoxanthine metabolites, acetylated amino acids, intermediates in phenylalanine metabolism, tyrosine, tryptophan metabolites, and riboflavin among the most relevant variables associated with external load. Metabolic network analysis identified enriched pathways including steroid hormone biosynthesis and metabolism of tyrosine and tryptophan. The ratio of players showing a deviation from the PLS model of adaptation to exercise was higher among those who suffered a muscular lesion compared to those who did not.

CONCLUSIONS

There was a significant association between the external load and the urinary metabolic profile, with alteration of biochemical pathways associated with long-term adaptation to training. Future studies should focus on the validation of these findings and the development of metabolic models to identify professional football players at risk of developing muscular injuries.

Urinary metabolites and risk of coronary heart disease: A prospective investigation among urban Chinese adults

BACKGROUND AND AIMS

Studies have linked several metabolites to the risk of coronary heart disease (CHD) among Western populations, but prospective studies among Asian populations on the metabolite-CHD association remain limited.

METHODS AND RESULTS

We evaluated the association of urinary metabolites with CHD risk among Chinese adults in a nested case-control study of 275 incident cases and 275 matched controls (127 pairs of men and 148 pairs of women). Fifty metabolites were measured by a predefined metabolomics panel and adjusted using urinary creatinine. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). After adjusting for traditional CHD risk factors, urinary tryptophan showed a positive association with incident CHD: OR (95% CI) for the highest vs. lowest quartiles was 2.02 (1.15-3.56) among all study participants (p-trend = 0.02). The tryptophan-CHD association was more evident among individuals with dyslipidemia than among those without the condition (OR [95% CI] for the highest vs. lowest quartiles = 3.90 [1.86-8.19] and 0.74 [0.26-2.06], respectively; p-interaction<0.01). Other metabolites did not show significant associations with CHD risk among all study participants. However, a positive association of methionine with CHD risk was observed only among women (OR [95% CI] for the highest vs. lowest quartiles = 2.77 [1.17-6.58]; p-interaction = 0.03), and an inverse association of inosine with CHD risk was observed only among men (OR [95% CI] for the highest vs. lowest quartiles = 0.29 [0.11-0.81]; p-interaction = 0.04).

CONCLUSION

Elevated urinary tryptophan may be related to CHD risk among Chinese adults, especially for those with dyslipidemia.

The effects of a sleep/recovery supplement: 'Night Time Recharge' on sleep parameters in young adults

BACKGROUND

Concentrated cherry juice reportedly contains melatonin which, in turn, has been highlighted as an important regulator in initiating sleep.

AIM

The present investigation aims to clarify whether Night Time Recharge (NTR), a marketed sleep aid containing cherry extract, improves key sleep parameters in young, active adults with mildly poor sleep.

METHODS

A double-blind, randomized, placebo-controlled, cross-over study design was employed. Twenty participants (nine female) consumed either NTR or a placebo for seven days. Accelerometers were used to assess sleep quality and physical activity levels. Urinary levels of 6-sulphatoxymelatonin (6-SMT), a marker of melatonin synthesis, was assessed via enzyme-linked immunosorbent assay.

RESULTS

6-SMT levels increased following NTR treatment (28.95 ng/ml) compared with placebo (4.0 ng/ml) (p < 0.001). There was also a significant difference (p = 0.047) in dietary tryptophan consumption during the NTR treatment (1236 mg) versus placebo (1149 mg). No trace of melatonin was detected from our analysis of the supplement. NTR had no significant effect on any sleep parameters with the exception of sleep latency (p = 0.001).

CONCLUSIONS

As chemical analysis of NTR by liquid-chromatography mass-spectrometry identified no detectable melatonin, the tryptophan content of the supplement is a likely reason for improvement in sleep latency. These results are in contrast to previous studies which have found a positive effect on sleep following cherry supplementation. Future work should focus on sleep latency and investigating whether cherry juice is effective in participants with problems in initiating sleep.

Specific Urinary Metabolites in Malignant Melanoma

Background and objectives: Melanin, which has a confirmed role in melanoma cell behaviour, is formed in the process of melanogenesis and is synthesized from tryptophan, L-tyrosine and their metabolites. All these metabolites are easily detectable by chromatography in urine. Materials and Methods: Urine samples of 133 individuals (82 malignant melanoma patients and 51 healthy controls) were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC). The diagnosis of malignant melanoma was confirmed histologically. Results: Chromatograms of melanoma patients showed increased levels of 5,6-dihydroxyindole-2-carboxylic acid, vanilmandelic acid, homovanilic acid, tryptophan, 5-hydroxyindole-3-acetic acid, and indoxyl sulphate compared to healthy controls. Concentration of indoxyl sulphate, homovanilic acid and tryptophan were significantly increased even in the low clinical stage 0 of the disease (indoxyl sulphate, homovanilic acid and tryptophan in patients with clinical stage 0 vs. controls expressed as medium/ interquartile range in µmol/mmol creatinine: 28.37/15.30 vs. 5.00/6.91; 47.97/33.08 vs. 7.33/21.25; and 16.38/15.98 vs. 3.46/6.22, respectively). Conclusions: HPLC detection of metabolites of L-tyrosine and tryptophan in the urine of melanoma patients may play a significant role in diagnostics as well as a therapeutic strategy of melanoma cancer.

Urinary Metabolites Altered during the Third Trimester in Pregnancies Complicated by Gestational Diabetes Mellitus: Relationship with Potential Upcoming Metabolic Disorders

Gestational diabetes mellitus (GDM) is a disorder in pregnancy with highest impact in the future life of both mother and newborn. Increasing incidence, economic impact, and potential for severe GDM-related pregnancy complications are some factors that have motivated the deep study of physiopathology, risk factors for developing GDM, and potential biomarkers for its diagnosis. In the present pilot study, we analyzed the urinary metabolome profile of GDM patients in the 3rd trimester of pregnancy, when GDM is already established and the patients are under dietary and pharmacological control. An untargeted metabolomics method based on liquid chromatography–mass spectrometry analysis was developed to identify differentially expressed metabolites in the GDM group. We identified 14 metabolites that are significantly upregulated in the urine of GDM patients, and, more importantly, we identified those related with the steroid hormone biosynthesis and tryptophan (TRP) metabolism pathways, which are associated with GDM pathophysiology. Thus, these metabolites could be screened as potential prognostic biomarkers of type two diabetes mellitus, coronary artery disease and chronic renal failure in future follow-up studies with GDM patients.

Exploratory metabolomics of nascent metabolic syndrome

INTRODUCTION

Metabolic syndrome (MetS) is a disorder defined by having three of five features: increased waist circumference (WC), hypertriglyceridemia, decreased high-density lipoprotein-cholesterol, hypertension and an elevated blood glucose (BG). Metabolic Syndrome ( MetS) affects 35% of American adults and significantly increases risk for Atherosclerotic cardiovascular disease (ASCVD) and type-2 diabetes (T2DM). An understanding of the metabolome will help elucidate the pathogenesis of MetS and lead to better management. We hypothesize that the metabolites, gamma-aminobutyric acid (GABA), d-pyroglutamic acid (PGA) and N-acetyl-d-tryptophan (NAT) will be altered in nascent MetS patients without the confounding of ASCVD or T2DM. We also correlated these metabolites with biomarkers of inflammation.

PATIENTS AND METHODS

This was an exploratory study of 30 patients with nascent MetS and 20 matched controls undertaken in 2018. Metabolites were evaluated from patient's frozen early morning urine samples and were correlated with biomarkers of inflammation and adipokines. They were assayed by the NIH Western Metabolomics Center using liquid chromatography/mass spectrometry and standardized to urinary creatinine. All patients had normal hepatic and renal function.

RESULTS

GABA and PGA levels were significantly increased in MetS patients compared to controls: 2.8-fold and 2.9-fold median increases respectively with p < 0.0001 and p = 0.004, possibly deriving from glutamate. NAT was significantly decreased by 90% in MetS patients compared to controls, p < 0.001. GABA correlates significantly with cardio-metabolic (CM) features including WC, blood pressure systolic (BP-S) while NAT correlated inversely with WC, BP-S, blood glucose (BG) and triglycerides (TG). GABA correlated positively with chemerin, leptin, Fetuin A and endotoxin. NAT correlated inversely with WC, BP-S, BG, TG, high sensitivity C - reactive protein (hsCRP), toll-like receptor-4 (TLR-4), lipopolysaccharide binding protein (LBP), chemerin and retinol binding protein-4 (RBP-4).

CONCLUSIONS

We make the novel observation of increased GABA and PGA with decreased NAT in patients with MetS. While GABA and PGA correlates positively with CM features and biomediators of inflammation, the metabolite NAT correlated inversely. Thus, GABA and PGA could contribute to the pro-inflammatory state of MetS while NAT could mitigate this pro-inflammatory response.

Tryptophan status in autism spectrum disorder and the influence of supplementation on its level

Recent reports show that the worldwide incidence of autism spectrum disorder (ASD) is dramatically increasing, although ASD etiology and pathogenesis are still far to be fully elucidated. Some dietary-derived essential compounds, such as the amino acid tryptophan, appear to be impaired in patients with ASD. Tryptophan (Trp) plays a significant role in the human organism and serves as a precursor for a wide range of bioactive compounds, including major neurotransmitters. Research indicates that tryptophan might be deficient in subjects with ASD. Deficiency in the tryptophan level can be retrieved by investigating Trp levels or its major metabolite kynurenine in urines. The purpose of the present study is to quantify tryptophan content in urine samples (n = 236) of ASD patients, who underwent a supplemented dietary panel with B vitamins and magnesium, compared to controls (without this diet regimen). The samples were analyzed with gas chromatography-mass spectrometry. Additionally, the correlation between body mass index (BMI) and the level of this amino acid in urine was accomplished. Basic parameters of urine samples were also evaluated. Statistical evaluations in the concentration of tryptophan in ASD patients with different severity of symptoms were reported. A significant difference in tryptophan levels in all groups was observed. Supplementation with B vitamins and magnesium has an influence on the Trp concentration. Furthermore, no correlation between BMI and tryptophan levels was found. These results assess that the Trp level in ASD subjects is critical and that intake of B vitamins and magnesium with diet might influence its metabolic homeostasis.

The kynurenine:tryptophan ratio as a predictor of incident type 2 diabetes mellitus in individuals with coronary artery disease

AIMS/HYPOTHESIS

The tryptophan metabolite kynurenine has potent immune modulatory and vasoactive properties. Experimental data implicate kynurenine in obesity-related morbidities. Epidemiological studies are, however, sparse. We evaluated associations of the plasma and urine kynurenine:tryptophan ratio (KTR) to incident type 2 diabetes.

METHODS

We followed 2519 individuals with coronary artery disease (CAD; 73.1% men) without diabetes at baseline for a median of 7.6 years, during which 173 (6.9%) new incidences of type 2 diabetes were identified. Multivariate Cox regression analyses were applied to investigate the prospective relationships of plasma and urine KTR with new onset type 2 diabetes.

RESULTS

At inclusion, mean (SD) age was 61.3 (10.4) years, BMI was 25.9 (3.71) kg/m2 and median (interquartile range) HbA1c was 5.6% (5.0%-6.0%) (38 [31-42] mmol/mol). Plasma KTR was not significantly related to type 2 diabetes risk. By contrast, urine KTR showed a strong positive association. Comparing quartile 4 with quartile 1, the HRs (95% CIs) were 2.59 (1.56, 4.30) and 2.35 (1.39, 3.96) in the age- and sex-adjusted and multivariate models, respectively.

CONCLUSIONS/INTERPRETATION

Urine KTR is a strong predictor of incident type 2 diabetes in individuals with CAD. Potential clinical implications and possible pathogenic roles of renal kynurenine excretion in type 2 diabetes development should be further elucidated.

Nonylphenol Toxicity Evaluation and Discovery of Biomarkers in Rat Urine by a Metabolomics Strategy through HPLC-QTOF-MS

Nonylphenol (NP) was quantified using liquid chromatography tandem mass spectrometry (LC-MS/MS) in the urine and plasma of rats treated with 0, 50, and 250 mg/kg/day of NP for four consecutive days. A urinary metabolomic strategy was originally implemented by high performance liquid chromatography time of flight mass spectrometry (HPLC-QTOF-MS) to explore the toxicological effects of NP and determine the overall alterations in the metabolite profiles so as to find potential biomarkers. It is essential to point out that from the observation, the metabolic data were clearly clustered and separated for the three groups. To further identify differentiated metabolites, multivariate analysis, including principal component analysis (PCA), orthogonal partial least-squares discriminant analysis (OPLS-DA), high-resolution MS/MS analysis, as well as searches of Metlin and Massbank databases, were conducted on a series of metabolites between the control and dose groups. Finally, five metabolites, including glycine, glycerophosphocholine, 5-hydroxytryptamine, malonaldehyde (showing an upward trend), and tryptophan (showing a downward trend), were identified as the potential urinary biomarkers of NP-induced toxicity. In order to validate the reliability of these potential biomarkers, an independent validation was performed by using the multiple reaction monitoring (MRM)-based targeted approach. The oxidative stress reflected by urinary 8-oxo-deoxyguanosine (8-oxodG) levels was elevated in individuals highly exposed to NP, supporting the hypothesis that mitochondrial dysfunction was a result of xenoestrogen accumulation. This study reveals a promising approach to find biomarkers to assist researchers in monitoring NP.

No Tryptophan, Tyrosine and Phenylalanine Abnormalities in Children with Attention-Deficit/Hyperactivity Disorder

Background

The aim of the current study was to explore the role of aromatic amino acids (AAAs) in blood in relation to attention-deficit/hyperactivity disorder (ADHD). Given their impact on the synthesis of serotonin and dopamine, decreased concentrations of the AAAs tryptophan, tyrosine and phenylalanine in blood may contribute to the expression of ADHD symptoms. Decreased AAA blood concentrations, in turn, may be related to lowered dietary protein intake or to abnormal AAA catabolism, as evidenced by increased urinary AAA concentrations.

Methods

Eighty-three children with ADHD (75% males) and 72 typically developing (TD) children (51% males), aged 6 to 13 years, participated in the study. AAA concentrations were assessed in blood spots and an 18-hour urinary sample. A nutritional diary was filled out by parents to calculate dietary protein intake. Parent and teacher questionnaires assessed symptoms of ADHD, oppositional defiant disorder, conduct disorder, and autism spectrum disorder.

Results

Children with ADHD showed normal AAA concentrations in blood spots and urine, as well as normal protein intake compared to controls. No associations between AAA concentrations and symptoms of ADHD or comorbid psychiatric disorders were found.

Conclusions

This study is the first to explore AAA metabolism in children with ADHD using a well-defined and relatively large sample. We found that AAA deficiencies are not related to ADHD. The results do not support treatment with AAA supplements in children with ADHD. Future studies regarding the cause of serotonin and dopamine alterations in ADHD should focus on other explanations, such as effects of altered transport of AAAs.

The Influence of Dietary Protein Intake on Mammalian Tryptophan and Phenolic Metabolites

Although there has been increasing interest in the use of high protein diets, little is known about dietary protein related changes in the mammalian metabolome. We investigated the influence of protein intake on selected tryptophan and phenolic compounds, derived from both endogenous and colonic microbial metabolism. Furthermore, potential inter-species metabolic differences were studied. For this purpose, 29 healthy subjects were allocated to a high (n = 14) or low protein diet (n = 15) for 2 weeks. In addition, 20 wild-type FVB mice were randomized to a high protein or control diet for 21 days. Plasma and urine samples were analyzed with liquid chromatography–mass spectrometry for measurement of tryptophan and phenolic metabolites. In human subjects, we observed significant changes in plasma level and urinary excretion of indoxyl sulfate (P 0.004 and P 0.001), and in urinary excretion of indoxyl glucuronide (P 0.01), kynurenic acid (P 0.006) and quinolinic acid (P 0.02). In mice, significant differences were noted in plasma tryptophan (P 0.03), indole-3-acetic acid (P 0.02), p-cresyl glucuronide (P 0.03), phenyl sulfate (P 0.004) and phenylacetic acid (P 0.01). Thus, dietary protein intake affects plasma levels and generation of various mammalian metabolites, suggesting an influence on both endogenous and colonic microbial metabolism. Metabolite changes are dissimilar between human subjects and mice, pointing to inter-species metabolic differences with respect to protein intake.

Simultaneous determination of three potential cancer biomarkers in rat urine by synchronous fluorescence spectroscopy

A rapid, simple, sensitive and accurate method for the simultaneous determination of three potential cancer biomarkers [tryptophan (TRP), isoxanthopterin (ISO) and xanthopterin (XAN)] in rat urine with synchronous fluorescence spectroscopy has been developed. In order to eliminate the interference in urine samples, the synchronous fluorescence spectra were obtained with Δλ=70 nm in a KH2PO4-NaOH buffer solution (pH=8.0). The detected wavelengths of quantitative analysis were set at 275 nm for TRP, 325 nm for ISO and 400 nm for XAN, respectively. Under the optimized conditions, the limits of the detection of the three compounds were 2.73 ng/mL, 0.52 ng/mL and 0.94 ng/mL, respectively. The recoveries were in the range of 80.5-98.0%, with the coefficient of variation between 0.62% and 2.48%. The proposed method has been applied to the simultaneous determination of TRP, ISO and XAN in rat urines of bladder cancer group and control group. The determination results showed that the average level of TRP, ISO and XAN had different change trends with the growth of the tumor. The three analytes could be used as potential biomarkers for noninvasive diagnosis of different stage of bladder cancer. However, more data are needed to support this hypothesis.

[Screening of urinary biomarkers in patients with type 2 diabetes mellitus]

OBJECTIVE

To screen the biomarkers of the middle-aged type 2 diabetes (T2DM) in urine based on metabolomics.

METHODS

First, both the metabolite profiles of morning urine sample in T2DM and control group were obtained by liquid chromatography-mass spectrometry (LC-MS). Second, an automated compound (feature) extraction algorithm was employed for processing background subtracted single MS data. Then principal component analysis (PCA) and t-Test analysis was followed after preprocessing on the extractive data. Third, identifying the potential biomarkers that show significant difference between the two groups by searching the database online and comparing the results of MS/MS experiments to those available in literature and those standards.

RESULTS

Three endogenous metabolites, among which tryptophan, kynurenic acid, and shown down-regulation while kynurenine shown up-regulation in T2DM, significantly differentiate between T2DM and control group.

CONCLUSION

Tryptophan, kynurenic acid and kynurenine may be considered as the potentail biomarkers related to T2DM.

A mathematical model of tryptophan metabolism via the kynurenine pathway provides insights into the effects of vitamin B-6 deficiency, tryptophan loading, and induction of tryptophan 2,3-dioxygenase on tryptophan metabolites

Vitamin B-6 deficiency is associated with impaired tryptophan metabolism because of the coenzyme role of pyridoxal 5'-phosphate (PLP) for kynureninase and kynurenine aminotransferase. To investigate the underlying mechanism, we developed a mathematical model of tryptophan metabolism via the kynurenine pathway. The model includes mammalian data on enzyme kinetics and tryptophan transport from the intestinal lumen to liver, muscle, and brain. Regulatory mechanisms and inhibition of relevant enzymes were included. We simulated the effects of graded reduction in cellular PLP concentration, tryptophan loads and induction of tryptophan 2,3-dioxygenase (TDO) on metabolite profiles and urinary excretion. The model predictions matched experimental data and provided clarification of the response of metabolites in various extents of vitamin B-6 deficiency. We found that moderate deficiency yielded increased 3-hydroxykynurenine and a decrease in kynurenic acid and anthranilic acid. More severe deficiency also yielded an increase in kynurenine and xanthurenic acid and more pronounced effects on the other metabolites. Tryptophan load simulations with and without vitamin B-6 deficiency showed altered metabolite concentrations consistent with published data. Induction of TDO caused an increase in all metabolites, and TDO induction together with a simulated vitamin B-6 deficiency, as has been reported in oral contraceptive users, yielded increases in kynurenine, 3-hydroxykynurenine, and xanthurenic acid and decreases in kynurenic acid and anthranilic acid. These results show that the model successfully simulated tryptophan metabolism via the kynurenine pathway and can be used to complement experimental investigations.

A pilot study on neopterin levels and tryptophan degradation in zinc-exposed galvanization workers

Hot-dip galvanization is a zinc-coating process to protect the metal items from corrosion. Zinc oxide nanoaerosol fume rising from hot metal bath surface in nano dimensions contains the greatest risk for workers in galvanization process. In the present study, it was evaluated whether inhalation of zinc causes any alteration in cellular immunity and tryptophan degradation by measuring neopterin, tryptophan, kynurenine, and zinc levels in 63 male galvanization workers and 23 male office personnel as controls. Serum and urinary zinc levels were found as 102.43 ± 4.74 and 0.66 ± 0.05 μg/dL in workers while 75.45 ± 4.24 and 0.80 ± 0.08 μg/dL [corrected] in controls, respectively (both, p < 0.05). Similarly, the mean urinary neopterin levels and serum neopterin and kynurenine levels were found to be statistically higher in galvanization workers than the controls (all, p < 0.05). Significant correlations were found between urinary neopterin levels and kynurenine to tryptophan ratio or serum zinc levels. The results indicated cellular immune activation by occupational zinc exposure. It was estimated that neopterin, in parallel with kynurenine pathway, could reflect occupational exposure to zinc nanoaerosols and might be useful in early diagnosis of immune alterations due to nano-scale exposures.

A voltammetric sensor for the simultaneous determination of L-cysteine and tryptophan using a p-aminophenol-multiwall carbon nanotube paste electrode

Two amino acids, L-cysteine and tryptophan, could be simultaneously determined in an aqueous solution (pH 6.0) using a carbon nanotube paste electrode (CNPE) modified with p-aminophenol as a mediator. The results indicate that the electrode is efficient in terms of its electrocatalytic activity for the oxidation of L-cysteine, leading to an overpotential reduced by more than 550 mV. Using differential pulse voltammetry, we could measure L-cysteine and tryptophan in one mixture independently from each other by a potential difference of about 600 mV. Electrochemical techniques are used to determine the diffusion coefficients, kinetic parameters such as electron transfer coefficient, and the rates of electro-oxidation of L-cysteine at the surface of the p-aminophenol-modified CNPE. The peak current is found to depend linearly on L-cysteine and tryptophan concentrations within the ranges of 0.5 - 100 µmol L(-1) L-cysteine and 10.0 - 300 µmol L(-1) tryptophan. The detection limits for L-cysteine and tryptophan are found to be 0.3 and 5.7 µmol L(-1), respectively. The proposed method is also used for the determination of L-cysteine and tryptophan in urine, river water, blood plasma, and serum samples using standard addition methods.

Determination of tryptophan in urine of autistic and healthy children by gas chromatography/mass spectrometry

BACKGROUND

Tryptophan is an amino acid, which is responsible for the production of serotonin in the body. Lower levels of tryptophan may play a role in pediatric disorders. In this work the urinary level of tryptophan in autistic and healthy children was compared.

MATERIAL/METHODS

The samples of urine were taken from 33 autistic children (10 on a restricted diet of gluten and casein free and 23 no diet) and 21 healthy children. The level of tryptophan was determined by gas chromatography/mass spectrometry (GC/MS). In this method tryptophan was derivatized and extracted simultaneously. The method was validated.

RESULTS

Significantly lower relative urinary levels of tryptophan were obtained for both autistic children with a restricted diet 1.98±1.17 µg/mL (mean ±SD) and autistic children without a diet 7.44±1.33 µg/mL (mean ±SD) compared to healthy children 14.24±2.01 µg/mL (mean ±SD). The method has a limit of quantification (LOQ) of 0.15 µg/mL and a lower limit of detection (LOD) of 0.04 µg/mL for tryptophan in urine.

CONCLUSIONS

This method is precise and sensitive for the detection of low concentrations of tryptophan and can be applicable to monitoring its level in human urine. Children with autism have a higher deficiency of tryptophan than the control group of healthy children. Lower levels of tryptophan may lead to the worsening of autistic symptoms such as mild depression and increased irritability.

[Biochemical and bacteriological investigation of six cases of purple urine bag syndrome (PUBS) in a geriatric ward for dementia]

AIM

Purple urine bag syndrome is a condition in which the urinary catheter bag turns purple. A tryptophan-indigo hypothesis has been proposed as the mechanism of PUBS, in which bacterial decomposition of tryptophan in gut associated with chronic constipation, bacterial overgrowth in the urinary tract and alkaline urine causes production of indigo and discoloration. We considered that further investigation of cases was needed.

METHODS

We investigated 6 cases exhibiting PUBS (3 males and 3 females).

RESULTS

All cases had chronic constipation. Oral ingestion was impossible in one case. PUBS disappeared after antibiotic treatment (3 cases) or spontaneously (one case). Alkaline urine and indicanuria were not found in all cases that showed the disappearance of PUBS. In bacterial culture of urine during the exhibition of PUBS, Enterococcus faecalis was isolated together with Morganella morganii (3 cases) and Pseudomonas aeruginosa (one case). Single infections by Klebsiella pneumoniae or Citrobacter species were also found. After disappearance of PUBS, infected bacterial species changed but no cases showed sterile urine. Urine and blood alpha-amino-n-butyric acid levels reduced after the disappearance of PUBS whereas tryptophan levels did not show related changes. In one case, blood protein concentration increased after the spontaneous disappearance of PUBS. Indicanuria and alkalization of urine from urinary catheter bag were more intense than of fresh urine.

CONCLUSIONS

The present results generally support the 'Tryptophan-indigo hypothesis'. Furthermore, it was suggested that additional factors associated with the occurrence of PUBS are an environment that facilitates specific bacterial growth in a hospital as well as abnormal metabolism relating to alpha-amino-n-butyric acid and reduced protein synthesis in patients.

Liquid chromatography method for detecting native fluorescent bioamines in urine using post-column derivatization and intramolecular FRET detection

Liquid chromatography (LC) with fluorescence detection is described for simultaneous determination of native fluorescent bioamines (indoleamines and catecholamines). This is based on intramolecular fluorescence resonance energy transfer (FRET) in an LC system following post-column derivatization of native fluorescent bioamines' amino groups with o-phthalaldehyde (OPA). OPA fluorescence was achieved through an intramolecular FRET process when the molecules were excited at maximum excitation wavelength of the native fluorescent bioamines. Bioamines separated by reversed-phase LC on ODS column were derivatized with OPA and 2-mercaptoethanol. This method provides sufficient selectivity and sensitivity for the determination of normetanephrine, dopamine, tyrosine, 5-hydroxytryptamine, tryptamine, and tryptophan in healthy human urine without prior sample purification.

Rapid and sensitive determination of tryptophan, serotonin and psychoactive tryptamines by thin-layer chromatography/fluorescence detection

A rapid, sensitive and selective method for the determination of tryptophan (Trp), serotonin (5-HT) and psychoactive tryptamines (PATs) by thin-layer chromatography (TLC) with fluorescence detection is proposed. These compounds form fluorophores on the developing plate by heating after spraying with sodium hypochlorite, hydrogen peroxide or potassium hexacyanoferrate(III)-sodium hydroxide reagent. Fluorescent spots (vivid blue) were observed by irradiation with ultraviolet light (365 nm). The detection limits of Trp, 5-HT and PATs were in the range from 0.01 microg to 0.06 microg. This method was effectively applied to the detection of confiscated PAT powder and PAT in abusers' urine samples.

Conversion ratio of tryptophan to niacin in Japanese women fed a purified diet conforming to the Japanese Dietary Reference Intakes

In order to establish the human requirements of niacin, it is first important to know how much tryptophan is converted to niacin in the human body. In a general, 60 mg of tryptophan is equivalent to 1 mg of niacin, whereas the conversion ratio of tryptophan to niacin is yet to be confirmed. The aim of this study was to know the conversion ratio of tryptophan to niacin in Japanese females fed a purified diet, which followed the Japanese Dietary Reference Intakes. Ten young Japanese females were housed in the same facility and given the same daily living activity schedule for 7 d. The composition of their purified diet was conformed to the Dietary Reference Intakes in Japan. The diet was niacin free. In order to investigate the conversion ratio, daily urinary outputs were collected. Tryptophan-niacin metabolites in the urine were measured and the conversion ratio of tryptophan to niacin calculated. The conversion ratio was calculated by comparing the dietary intake of tryptophan and the sum of the niacin catabolites such as N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, which were derived only from the dietary intake of tryptophan. The ratio was calculated as 1.5 +/- 0.1 (mean +/-SE for 10 women; in molar basis) on the last day of the experiment. It was calculated that if the excretory percentage of niacin metabolites in the urine were 60%, of the tryptophan ingested, the conversion factor would be a value of 67, meaning that is 67 mg of tryptophan is equal to 1 mg of niacin.

Changes in the urinary excretion of the metabolites of the tryptophan-niacin pathway during pregnancy in Japanese women and rats

NAD is biosynthesized from tryptophan. Therefore, experimental studies including tryptophan metabolism studies could provide insight into niacin nutrition in pregnancy. Our aim was to determine the change in niacin metabolism during pregnancy by a systemic investigation of how pregnancy alters the tryptophan-niacin metabolism in Japanese women and rats. For the human study, spot urine samples were collected from a total of 434 pregnant Japanese women who were at 5-40 wk of gestation, 50 women at 4-6 wk postpartum, and 10 nonpregnant women as the controls. For the animal study, pregnant rats were fed with a niacin-free diet, and daily urine samples were collected from day 6 of gestation to day 6 postpartum. The intermediates and metabolites of the tryptophan-niacin pathway in the urine samples were measured. The urinary excretions of niacin metabolites in humans and rats increased from mid pregnancy in a time-dependent manner, reached a peak of 2-3-fold during late pregnancy, and declined to control levels after childbirth.

Separation and determination of L-tryptophan and its metabolites by capillary micellar electrokinetic chromatography with amperometric detection

A high-performance method of capillary micellar electrokinetic chromatography (CMEKC) with amperometric detection (AD), using a newly designed pre-aligned electrochemical cell, has been developed for the separation and determination of L-tryptophan (Trp) and its eight metabolites including 3-hydroxy-L-kynurenine (3-HK), 5-hydroxy-L-tryptophan (5-HTP), L-kynurenine (KN), 5-hydroxyindole-3-acetic acid (5-HIAA), xanthurenic acid (XA), indole-3-pyruvic acid (IPA), 5-hydroxytryptamine (5-HT), and tryptamine (Tryp). A carbon disk electrode was used as the working electrode and the optimal detection potential was 0.85 V (versus Ag/AgCl). At 24 kV of applied voltage, the nine compounds were completely separated, within 23 min, in a 10 mol/L Na(2)HPO(4)-NaOH buffer (pH 11.0) containing 40 mmol/L sodium dodecyl sulfate (SDS) and 3% methanol (v/v). A good linear relationship was obtained for all analytes in this paper and the detection limits of 3-HK, 5-HTP, KN, Trp, 5-HIAA, XA, IPA, 5-HT, and Tryp were 7.42, 5.18, 34.6, 3.99, 15.1, 12.7, 260, 6.72, and 8.01 nmol/L, respectively. This method has been applied to analyze the metabolism of Trp in rabbit urine.

A clinicobiochemical study of tryptophan and other plasma and urinary amino acids in the family with Hartnup disease

Two cases of Hartnup disease were diagnosed in a five member family. A changeable polymorph and severe clinical features of a 16 year old girl was described. Total plasma amino acids value was significantly decreased in the girl compared to the sum of plasma amino acids value in the brother, mother, father and to the summed maximal values of normal range. Intermediate aminoaciduria was also found with atypical amino acids pattern. Total plasma amino acids concentration was significantly reduced (27.20%) in the mother, while no significant decrease in the son (1.83%) and father (7.51%) were found compared to the summed maximal values of normal range. In the clinicaly healthy father, 38 years of age, a gross aminoaciduria with atypical pattern of amino acids was also found. Urinary amino acids concentration in the son and his mother were rather normal, although low concentration of eight amino acids was found in the mother's urine. Cerebrospinal fluid 5-hydroxyindoleacetic acid level was reduced in the girl.

Electrophoretic separation of tryptophan enantiomers in biological samples

A method for the determination of D- and L-tryptophan (Trp) in biological samples is described. The amino acid enantiomers were precolumn-derivatized with a fluorescence tagging reagent, naphthalene-2,3-dialdehyde (NDA). In the presence of hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD) as the chiral selector, NDA-tagged Trp enantiomers were well resolved by micellar electrokinetic chromatography (MEKC). Using laser induced fluorescence (LIF) detection, a detection limit of 3.3 x 10(-8) M Trp was obtained. The method was applied to the determination of Trp enantiomers in biological samples including human urine and cerebrospinal fluid (CSF), rat brain tissue, and Aplysia ganglia. No interference from other amino acids or the endogenous compounds in the sample matrices was observed. D-Trp was found at the sub-microM level in human urine samples collected from several healthy subjects. Further, the determination of DL-Trp residues in small quantities (10 microg) of peptides after acid hydrolysis is demonstrated.

Serum tryptophan to large neutral amino acid ratio and urinary tryptophan in three patients with phenylketonuria in a family. A clinical and biochemical study

In this work clinical and biochemical findings are presented in three untreated children with phenylketonuria in a family. Their clinical pictures were not typical for classical phenylketonuria. As a result, diagnosis was missed. It has been shown that patterns of large neutral amino acids in serum and urine were somewhat different. Significantly lower serum TRP/LNAA ratio was observed in all patients with phenylketonuria, compared to the control group. These findings suggest that there was subnormal tryptophan availability in the central nervous system leading to its decreased metabolism through the serotonin and kynurenine pathways. These results may explain decreased children's growth and their mental deficiency.

Capillary zone electrophoresis separations of enantiomers present in complex ionic matrices with on-line isotachophoretic sample pretreatment

Analytical capabilities of capillary zone electrophoresis (CZE) with on-line coupled capillary isotachophoresis (ITP) sample pretreatment in the column-coupling capillary electrophoresis equipment to separate and determine enantiomers present in multicomponent ionic matrices were studied. Tryptophan was used as a model analyte in the ITP-capillary zone electrophoresis experiments performed in this context while a 90-component model mixture of UV-light absorbing organic anions and urine served as multicomponent sample matrices. Various working modes in which the on-line coupled capillary isotachophoresis-capillary zone electrophoresis combination in the column-coupling separation system can operate were employed in the anionic regime of the separation with direct injections of the samples. Advantages and limitations of these working modes in the separations of enantiomers present in model and urine matrices were assessed. Experiments with model mixtures of tryptophan enantiomers revealed that the two were resolved in the capillary zone electrophoresis stage with the aid of alpha-cyclodextrin also when their concentration ratio in the sample was 1:200 while the concentration of L(-)-tryptophan was 25 nmol/l. The limits of detection for the enantiomers were at approximately 10 nmol/l (approximately 1.5 ng/ml) concentrations for a 220 nm detection wavelength of the UV detector employed in the capillary zone electrophoresis stage and for a 30 microliters sample load. A high sample load capacity of the on-line coupled capillary isotachophoresis stage was effective in separating the samples corresponding to 3-6 microliters volumes of undiluted urine. The results from the runs with urine samples showed that only the capillary isotachophoresis-capillary zone electrophoresis combination with a post-column on-line coupled capillary isotachophoresis sample clean-up (responsible for a removal of more than 99% of the sample anionic constituents migrating in the on-line coupled capillary isotachophoresis stack and detectable in the capillary zone electrophoresis stage) provided a universal alternative for the detection and quantitation of the model analyte (L(-)-tryptophan).

Increased conversion ratio of tryptophan to niacin by the administration of clofibrate, a hypolipidemic drug, to rats

The effect of clofibrate, a hypolipidemic drug and also known as a peroxisomal proliferator, on the conversion ratio of tryptophan to niacin was investigated by using rats. The rats were fed with a nicotinic acid-free, 20% casein diet (control group) or the same diet + 0.25% clofibrate group) for 19 days. The conversion ratio gradually increased with increasing number of days. Around day 8, the ratio was about 10-times higher in the clofibrate group than in the control group, and the value remained almost constant after that day. The content of liver total nicotinamide was higher in the clofibrate group than in the control group. Among the enzymes involved in the conversion of tryptophan to niacin, the aminocarboxymuconate-semialdehyde decarboxylase (ACMSDase) activity, which is critical in the conversion, was lower in the clofibrate group than in the control group. As the change in ACMSDase activity took several days, there is a possibility that clofibrate decreased the biosynthesis of ACMSDase protein and/or mRNA. To learn whether the increase in the conversion ratio by clofibrate would be nutritionally meaningful or not, the growth-promoting activity of clofibrate was determined by using weanling rats fed with a nicotinic acid-free, tryptophan-limiting diet (basal diet). As a result, the body weight gain was higher in the clofibrate group than in the basal group. This result shows that clofibrate enhanced the conversion ratio without any side-effects under the conditions used and supports again the claim that the activity of ACMSDase exerts a critical influence on the tryptophan-NAD conversion.

[A tryptophan metabolic disorder in patients with kidney tumors]

Tryptophan metabolism was investigated in 108 patients with renal tumors and 449 controls. Histologically verified (96.2%) hypernephroid cancer and papillary pelvic cancer were recorded in 84.3 and 15.4% of patients, respectively. Endogenic carcinogen 3-oxy-antronilic acid (3-OAA) was found in the urine of 17.6% of patients vs. 5.6% of controls. The difference was statistically significant. 3-oxykinurenin was detected in 6.5% of patients. The difference with controls was insignificant. Tryptophan metabolism was specified in respect to tumor histology and sex.

Effects of tryptophan load on amino acid metabolism in type 1 diabetic patients

Tolerance to an oral tryptophan load (50 mg/kg body weight) was evaluated in a group of 15 insulin-dependent diabetic patients of both sexes in poor metabolic control. Tryptophan was measured fluorometrically, and the plasma levels of the other physiological amino acids were determined by HPLC. The ratio of the plasma concentration of each large neutral amino acid (LNAA) to the sum of the others was calculated to serve as an index for the competitive transport of these amino acids into the brain. The results show that post-loading plasma tryptophan levels in diabetic patients increased less than in healthy controls, suggesting enhanced liver catabolism of this amino acid (as reported for diabetic animals). Small changes were observed in the post-loading plasma concentrations of other amino acids. Therefore, the increment in the tryptophan/LNAA ratio in controls (basal, 0.12 +/- 0.01; 120 min after the load, 0.89 +/- 0.04; 240 min, 0.51 +/- 0.03) was greatly attenuated in diabetic patients (basal, 0.11 +/- 0.01, NS; 120 min, 0.46 +/- 0.04, p < 0.01; 240 min, 0.31 +/- 0.04, p < 0.01). Post-loading excursions in some other ratios were slightly larger in control than diabetic subjects. These differences, which may occur to a lesser extent after a protein-rich meal, could modify the availability of precursor amino acids to the brain for synthesis of neurotransmitters. Thus, as happens in certain animal species, an impairment of the post-absorptive accumulation of tryptophan and serotonin in the brain may occur in diabetic patients as a result of altered metabolic disposal of tryptophan.

Congenital non-progressive encephalopathy and deafness with intermittent episodes of coma and hyperkynureninuria

Six of nine children born from first-cousin parents presented with the same clinical picture: non-progressive congenital encephalopathy with marked hypertonia resembling the stiff-baby syndrome, delayed milestones, mental deficiency and congenital deafness. Rare, usually reversible, episodes of sudden worsening of the neurological status, with progressive loss of consciousness and increase of hypertonia, occurred spontaneously or during febrile illnesses. During these periods, and sometimes on other occasions, transitory renal dysfunction was observed (nephrotic syndrome and/or tubular abnormalities). Death occurred before age 2 years in 4 patients; 2 are still alive (10 and 13 years old). Electrophysiological, biological and enzymatic investigations remained negative, particularly those concerning mitochondrial and peroxisomal metabolism. The only biochemical anomaly was a massive hyperkynureninuria, seen only during the periods of coma (up to 213 mumol/mmol creatinine; normal < 10) and after an intravenous protein loading test. This suggests an anomaly of tryptophan metabolism which has not been reported up to now.

Familial hypertryptophanemia in two siblings

Mild and moderate mental retardation with exaggerated affective responses, periodic mood swings, and apparent hypersexual behavior were present in two siblings with hypertryptophanemia and tryptophanuria. In addition, the male had severe myopia, a speech impediment, musculoskeletal abnormalities and perceptual hypersensitivity. His sister was deaf, which was ascribed to antenatal rubella. The occurrence in siblings and the presence of abnormal urinary tryptophan metabolite in the mother and a half-sibling suggest that the condition results from an autosomal recessive gene with minor expression in some heterozygotes.

Determination of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and tryptophan in plasma and urine by HPLC with fluorimetric detection

Using native fluorescence detection, 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and tryptophan were resolved from themselves and other naturally occurring compounds using reversed-phase HPLC within 5 min. Deproteinated platelet-poor plasma (PPP) and crude diluted urine were injected directly into the chromatograph. Careful selection of the HPLC column is important and various octadecyl silica (ODS) and base deactivated silic (BDS) columns were evaluated. Pre-treatment of an ODS column with tetrabutylammonium ions gave good selectivity. Between pH 5 and 6 the compounds were well resolved from each other. The limit of quantitative detection of 5-HT and 5-HIAA was 3.5 nmol/L. The overall chromatogram obtained using native fluorescence is cleaner than that obtained with the more commonly employed electrochemical (EC) systems although the chromatography is effectively the same. For analysis of 5-HT in plasma, collection in EDTA was more efficient than lithium heparin. Plasma 5-HT in healthy volunteers was mean 61 (SD = +/- 73) nmol/L, n = 20; urine 5-HIAA gave mean 28.95 (SD = +/- 0.98) mumol/L, (n = 12). Whole blood 5-HT analysis is unreliable in comparison with platelet-poor plasma.

High performance liquid chromatographic profiling of tryptophan and related indoles in body fluids and tissues of carcinoid patients

A high performance liquid chromatographic method with quaternary gradient elution and fluorometric detection was developed for profiling of tryptophan (TRP), 5-hydroxytryptophan, serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in urine, platelet-rich plasma and (tumour) tissue of patients with carcinoid tumours. Prior to injection, urine samples were diluted and filtered. Platelet-rich plasma and tissue homogenates were prepurified by C18 solid phase extraction. Detection limits were approx. 2 pmol. Results of urinary 5-HT and 5-HIAA compared favourably with those of single component analyses. No consistent diurnal variations were found for TRP, 5-HT and 5-HIAA in 12-h urine samples from 15 healthy adults. Abstinence of 5-HT-rich foods reduced urinary levels of 5-HT and 5-HIAA. C18 extraction of indoles from protein-containing matrices was studied in platelet-rich plasma. Although time-consuming and complicated for daily routine use, the present approach offers particular advantages over single component analyses in the study of TRP metabolism in patients with carcinoid tumours.

Simultaneous analyses of monoamines and their metabolites in urine specimens of patients with neuroblastoma

1. Tyrosine and tryptophan, as well as 26 metabolites of these amino acids, were analyzed simultaneously in urine specimens from patients with neuroblastoma and control infants by a three-dimensional HPLC system to develop an early diagnosis. 2. Levels of detected compounds in urine from patients with neuroblastoma were generally higher in the case of catecholamines and lower in the case of indolalkylamines than those in controls. 3. The pathways of Dopamine-3,4-Dihydroxyphenylacetic acid-Vanillylmandelic acid, Dopamine-3-Methoxy-4-hydroxyphenylethylene glycol-Vanillylmandelic acid and Tyrosine-4-Hydroxyphenylacetic acid-4 were, in particular, found to be active in patients with neuroblastoma.

Studies on serum beta-glucuronidase activity and urinary tryptophan metabolites in human fascioliasis

In the last few years, human fascioliasis has been reported more frequently from different parts of the world including Egypt. The present work aimed to study the ability of fascioliasis affected patients to metabolize tryptophan and to explore how this disease can affect the activity of the hydrolytic lysosomal enzyme beta-glucuronidase. Liver and kidney functions and complete blood pictures of the studied patients were considered. Eleven tryptophan metabolites together with 4-pyridoxic acid, the major metabolite of vitamin B6, were determined. Fascioliasis showed an abnormal pattern of tryptophan metabolism which resembled that described earlier by Kupke and Knapp and which indicated that those patients were suffering from vitamin B6 deficiency. This conclusion was proved by the decreased levels of 4-pyridoxic acid. Abnormally high levels of beta-glucuronidase were also encountered in the fascioliasis cases which points to the liver damage caused by the fluke.

The urinary excretion of tryptophan and tryptophan metabolites in the chronic ethanol-fed rat

An investigation was made into the hypothesis that chronic ethanol ingestion disturbs the metabolism of tryptophan which is reflected by alterations in the urinary excretion of the metabolites 5-hydroxyindoleacetic acid (5-HIAA), anthranilic acid (AA) and indoleacetic acid (IAA). In particular, we investigated whether experimental chronic alcoholism is associated with a decrease in the tryptophan metabolite ratios as suggested in the literature. Male Wistar rats were chronically fed a nutritionally-complete liquid diet in which ethanol comprised 35% of total calories: controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. At 6 weeks, 24 h urine samples were collected for the analysis of tryptophan, 5-HIAA, AA and IAA by HPLC. During ethanol-feeding there were reductions in the daily urinary excretion (i.e. mumol/24 h) of tryptophan (-57%, P = 0.026) and concomitant increases in 5-HIAA excretion (62%, P = 0.057). Expression of data in terms of lean tissue mass (i.e. urinary creatinine) revealed identical conclusions. An analysis was performed on the molar ratios of these urinary analytes. The tryptophan: total metabolite ratio was significantly decreased (by -53%), but the AA: total metabolite ratio was not significantly altered (P = 0.102). The ratios 5-HIAA/AA and 5-HIAA/IAA were slightly increased, but they did not attain statistical significance (P > 0.351). It was concluded that chronic ethanol feeding is associated with significant changes in the urinary excretion of tryptophan and its related metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

[The characteristics of the hormonal status in women with bladder neoplasms]

In a controlled trial a gynecological history has been studied for 154 females with bladder tumors against 213 matched women without the tumor. The risk to develop the tumor was found to rise with the history of a short reproductive period, abortions, primary infertility, cancer of the corpus uteri and of the breast, ovarian cysts. Tryptophan metabolism assessed in 242 and 541 women and men with bladder cancer and free of it, respectively, was indicative of more frequent urinary registration of carcinogenic tryptophan metabolite 3-oxyantranilic acid: for females 40.5 per 100 in case of cancer, 10 per 100 in healthy ones; for males with cancer 33.9, without cancer 7.4 per 100 examinees. Radioimmunoassays of hormone concentrations in the serum with correlation to tryptophan metabolism for 55 cancer and 49 healthy females showed lowered levels of progesterone, folitropin and lutropine to occur more often in cancer women with urinary 3-oxyantranilic acid. The above endogenic factors analyzed retrospectively suggest involvement of hormonal status alterations in bladder cancer onset.

Free amino acids during chronic cyclosporine A toxicity in intact and partially nephrectomized rats

The effects of 40 days of treatment with Cyclosporine A (CSA) on plasma and urine free amino acids were investigated in sham-operated (C) and partially nephrectomized (Pnx) female Fischer 344 rats. High Dose CSA (30 mg/kg/day ip) was associated with reduced weight gain, increased plasma urea nitrogen, and hypoproteinemia in C and Pnx animals. These animals also demonstrated increased plasma levels of alanine, markedly reduced levels of tryptophan, and an increase in urinary excretion of methylhistidines. C but not Pnx animals also showed a significant increase in plasma serine and a decrease in plasma taurine. CSA treatment of group C resulted in a progressive aminoaciduria involving substrates of the neutral and acidic renal amino acid transport systems; however, the renal excretion of taurine and beta-alanine by these animals was markedly reduced as compared to vehicle treated controls. High dose CSA exacerbated aminoaciduria in Pnx animals, but in this group, the excretion of beta amino acids was also increased. Our findings demonstrate that chronic CSA toxicity in rodents with normal renal function is characterized by increased muscle protein catabolism, significant reductions in plasma tryptophan, and an apparent decrease in whole body taurine pools. With the exception of the taurine abnormalities. CSA treatment had similar effects on Pnx animals; however, in this group, CSA-induced pathological changes were superimposed on the changes due to renal insufficiency per se. CSA toxicity as identified by the parameters investigated in this study was no more severe in Pnx animals with moderate chronic renal insufficiency than in controls with intact renal function.

High-performance liquid chromatographic measurement of tryptophan in blood, tissues, urine, and foodstuffs with electrochemical and fluorometric detections

A rapid and convenient measurement of tryptophan in whole blood, serum, liver, brain, urine, and alkaline hydrolysates of proteins and foodstuff was done by high-performance liquid chromatography. The sample preparation was simply homogenized or mixed in a 5% trichloroacetic acid solution and a sample of the supernatant was injected onto a column after filtration with a 0.45-micron filter. The method used a Chemcosorb 5-ODS-H column (particle size, 5 microns, 150 x 4.6 mm i.d.) eluted with 20 mM potassium dihydrogen phosphate (pH adjusted to 3.7 by the addition of phosphoric acid) containing 1 g/l of sodium heptane sulfonate and 3 mg/l EDTA.2Na-acetonitrile (93:7, v/v) at a flow rate of 1.5 ml/min. The tryptophan contents in whole blood, serum, liver, and brain were electrochemically estimated at +1000 mV vs. Ag/AgCl, the detection limit being 0.2 pmol (40.84 pg) at a signal-to-noise ratio of 5:1. The tryptophan contents in urine, proteins, and foodstuff were fluorometrically estimated with an excitation wavelength of 280 nm and with an emission wavelength of 340 nm, the detection limit being 20 pmol (4.08 ng) at a signal-to-noise ratio of 5:1. Tryptophan was eluted at about 10.5 min. The total analysis time was about 12 min.

Simultaneous determination of urinary creatinine and aromatic amino acids by cation-exchange chromatography with ultraviolet detection

A cation-exchange chromatographic procedure for the simultaneous determination of urinary creatinine and aromatic amino acids is described. Creatinine and amino acids were separated from organic acids and/or neutral species in urine by using a preparative cation-exchange resin column. A column packed with a cation-exchange resin of low capacity was used for the analytical separations. The elution of creatinine and aromatic amino acids was monitored at 210 nm by means of an ultraviolet detector. The relationships between concentration and peak heights were reproducible with a coefficient of variation of less than 2%, and were linear from 5 to 200 microM for each compound. Overall recoveries of the analytes were more than 95%. The method was applied to the analysis of urine of patients with disorders of amino acid metabolism, such as phenylketonuria. The concentration ratios of phenylalanine to creatinine in the patients' urine were accurately and easily determined, and were quite different from those in the urine of healthy newborns.