High Phe Levels Research Articles

The association of aromatic amino acids with coronary artery disease and major adverse cardiovascular events in a Chinese population

This study aimed to evaluate the relationship between aromatic amino acids (AAAs), – phenylalanine (Phe), tyrosine (Tyr) and tryptophan (Trp) – and coronary artery disease (CAD) in a prospective study involving 2970 participants undergoing coronary angiography at Beijing Hospital. Serum levels of Phe, Tyr and Trp were analysed. The cross-sectional data revealed that serum Tyr and Trp levels were significantly and inversely associated with CAD. During a median follow-up period of 44 months, 343 major adverse cardiovascular events (MACEs) and 138 all-cause deaths were recorded. MACE included myocardial infarction, stroke, revascularisation and all-cause mortality. Low serum Trp levels predicted an increased risk of MACE and death. High serum Phe levels were linked to an increased risk of MACE, while low Tyr levels were associated with a higher risk of death. Collectively, our findings underscore a close correlation between AAAs and CAD, as well as their potential predictive value for adverse cardiovascular outcomes.

Do early‐treated adults with phenylketonuria sense high phenylalanine levels?

AbstractThis study aimed to analyze whether early‐treated adults with phenylketonuria (PKU) can subjectively sense high phenylalanine (Phe) concentrations and whether a possible impact of Phe on objective measures of cognitive performance and mood reflects patients' self‐perception. Data from the PICO study, a randomized, placebo‐controlled, double‐blind, crossover trial, were analyzed. Twenty‐eight adults with PKU received either Phe capsules or placebo in two 4‐week intervention periods in a randomized order, with a 4‐week washout in between. The median Phe level increased from 852 μmol/L (interquartile range: 345) to 1455 μmol/L (interquartile range: 369). Neuropsychological assessments were performed at four study visits. At the end of the last study visit, patients were asked whether they could discern the Phe intervention period. Seven of 28 (25%) patients stated that they could not discern between the Phe and the placebo period. Twenty‐one of 28 (75%) patients subjectively thought to sense high Phe levels. Of the 21 patients, 12 (57%) correctly identified the Phe period, whereas 9 (43%) received placebo at the time when they thought they would receive the high Phe load. Binomial tests showed that the probability of 12 out of 21 is p = 0.140, and 12 out of 28 is p = 0.113. The “Right‐Guess” group showed significantly higher Phe changes than the “Wrong‐Guess” group. Cognitive performance and standardized mood assessment did not significantly differ, and both groups reported similar subjective negative impact on cognition and mood. In conclusion, adults with early‐treated PKU cannot effectively identify high Phe levels, although some individuals may be able to perceive more pronounced increases in Phe levels.

The relationship between working memory and anxiety in individuals with early treated phenylketonuria (PKU).

Although early diagnosis and treatment prevent the severe impairments associated with untreated phenylketonuria (PKU), individuals with early treated PKU (ETPKU) nonetheless experience significant neurocognitive and psychological sequelae, including difficulties in working memory (WM) and increased risk of anxiety. The primary objective of the present study was to examine the extent to which anxiety may moderate the relationship between ETPKU and WM performance. A sample of 40 adults with ETPKU and a demographically comparable sample of 40 healthy adults without PKU completed a comprehensive assessment of WM performance and anxiety symptomatology. Data were collected using a variety of remote assessment methods (e.g., web-based neurocognitive tests, semistructured interview, report-based measures). The ETPKU group demonstrated significantly poorer WM performance as compared to the non-PKU group. The groups did not differ significantly in anxiety; however, high anxiety was more common in the ETPKU group (53% of sample) than the non-PKU group (33%). A significant interaction between anxiety, metabolic control (as reflected by Phe levels), and WM performance was observed for the ETPKU group. Individuals with high anxiety and/or high Phe levels (> 360 μmol/L) performed poorer than the non-PKU group. Individuals with low anxiety and relatively low Phe levels (< 360 μmol/L) performed comparably to the non-PKU group. Anxiety was found to moderate the relationship between Phe levels and WM performance in individuals with ETPKU. This finding underscores the importance of accounting for anxiety when evaluating neurocognitive performance in individuals with ETPKU whether for research or clinical purposes. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Efficacy and safety of sapropterin before and during pregnancy: Final analysis of the Kuvan® Adult Maternal Paediatric European Registry (KAMPER) maternal and Phenylketonuria Developmental Outcomes and Safety (PKUDOS) PKU-MOMs sub-registries.

Infants born to mothers with phenylketonuria (PKU) may develop congenital abnormalities because of elevated phenylalanine (Phe) levels in the mother during pregnancy. Maintenance of blood Phe levels between 120 and 360 μmol/L reduces risks of birth defects. Sapropterin dihydrochloride helps maintain blood Phe control, but there is limited evidence on its risk-benefit ratio when used during pregnancy. Data from the maternal sub-registries-KAMPER (NCT01016392) and PKUDOS (NCT00778206; PKU-MOMs sub-registry)-were collected to assess the long-term safety and efficacy of sapropterin in pregnant women in a real-life setting. Pregnancy and infant outcomes, and the safety of sapropterin were assessed. Final data from 79 pregnancies in 57 women with PKU are reported. Sapropterin dose was fairly constant before and during pregnancy, with blood Phe levels maintained in the recommended target range during the majority (82%) of pregnancies. Most pregnancies were carried to term, and the majority of liveborn infants were reported as 'normal' at birth. Few adverse and serious adverse events were considered related to sapropterin, with these occurring in participants with high blood Phe levels. This report represents the largest population of pregnant women with PKU exposed to sapropterin. Results demonstrate that exposure to sapropterin during pregnancy was well-tolerated and facilitated maintenance of blood Phe levels within the target range, resulting in normal delivery. This critical real-world data may facilitate physicians and patients to make informed treatment decisions about using sapropterin in pregnant women with PKU and in women of childbearing age with PKU who are responsive to sapropterin.

Effect of a four-week oral Phe administration on neural activation and cerebral blood flow in adults with early-treated phenylketonuria

BackgroundPhenylketonuria (PKU) is a rare inborn error of metabolism characterized by impaired catabolism of the amino acid phenylalanine (Phe) into tyrosine. Cross-sectional studies suggest slight alterations in cognitive performance and neural activation in adults with early-treated PKU. The influence of high Phe levels on brain function in adulthood, however, remains insufficiently studied. Therefore, we aimed to explore the effect of a four-week period of oral Phe administration − simulating a controlled discontinuation of Phe restriction and raising Phe to an off-diet scenario − on working memory-related neural activation and cerebral blood flow (CBF). MethodsWe conducted a randomized, placebo-controlled, double-blind, crossover, non-inferiority trial to assess the effect of a high Phe load on working memory-related neural activation and CBF in early-treated adults with classical PKU. Twenty-seven patients with early-treated classical PKU were included and underwent functional magnetic resonance imaging (fMRI) of the working memory network and arterial spin labeling (ASL) MRI to assess CBF before and after a four-week intervention with Phe and placebo. At each of the four study visits, fMRI working memory task performance (reaction time and accuracy) and plasma Phe, tyrosine, and tryptophan levels were obtained. Additionally, cerebral Phe was determined by 1H-MR spectroscopy. ResultsPlasma Phe and cerebral Phe were significantly increased after the Phe intervention. However, no significant effect of Phe compared to placebo was found on neural activation and CBF. Regarding fMRI task performance, a significant impact of the Phe intervention on 1-back reaction time was observed with slower reaction times following the Phe intervention, whereas 3-back reaction time and accuracy did not differ following the Phe intervention compared to the placebo intervention. ConclusionResults from this present trial simulating a four-week discontinuation of the Phe-restricted diet showed that a high Phe load did not uniformly affect neural markers and cognition in a statistically significant manner. These results further contribute to the discussion on safe Phe levels during adulthood and suggest that a four-week discontinuation of Phe-restricted diet does not demonstrate significant changes in brain function.

Adult PKU Clinics in the UK-Users' Experiences and Perspectives.

Adults with PKU require life-long management, and ideally, their care should be in a specialised adult metabolic clinic. Their outcomes and co-morbidities have received much attention, but data are lacking on their experience, satisfaction and expectations about the care they receive. This survey reports the experiences and care adults with PKU receive from specialist metabolic clinics in the UK. The online survey developed by the UK NSPKU (National Society for Phenylketonuria), was placed on the NSPKU website from February 2021 to December 2022, and was completed by adults with PKU (≥18 years) or their carers/family members. Sixty-five adult PKU patients and 9 caregivers of adult patients completed the questionnaire (63% female in total). Only 32% of respondents were following a Phe-restricted diet with protein substitute intake as prescribed; the rest were partially adherent or not on dietary restrictions. Nineteen per cent (n = 14/74) had not been reviewed in clinic for two years. Half of the respondents (50%) described their experience in adult clinics as "good". Half of the patients were unable to contact their dietitians with questions or concerns, and only 24% considered that they received adequate support. Clinic reviews usually included anthropometric (82%) and dietary assessments (64%), discussion on management of PKU in daily life (78%) and a blood test (71%). Eighty-eight per cent reported they had at least one neurocognitive, mental health or behavioural co-morbidity but less than half of the patients reported an assessment on their neurocognitive functioning or mental health issues. Adult male patients appeared to have less detailed clinic review than females. Less than half (44%) of the respondents reported that they performed a blood spot for blood Phe at least monthly, but only 32% considered they had been informed about the risk of high Phe levels in adulthood. Although time, cost and stress related to travelling were barriers to a face-to-face review, more than 40% of patients had concerns about remote appointments. The frequency and extent of monitoring of adults with PKU, attending specialist adult services, were less than those specified by the PKU European guidelines. The care of women of reproductive age is prioritised over men. Adult metabolic health services require further attention, development and resources to provide a high standard and equitable service to patients with PKU.

Long-Term Renal Function in Adult Patients with Phenylketonuria

Introduction: In phenylketonuria (PKU), toxic phenylalanine (Phe) can harm other organs beyond the brain. Furthermore, the lifelong therapy of PKU consists of consumption of increased amounts of amino-acid mixture that provoke hyperfiltration in the glomeruli. Therefore, the adherence to therapy in PKU might influence the long-term kidney function in PKU patients. Methods: Data from 41 adult, early treated PKU patients were analyzed in this 10-year, retrospective, monocentric study. Two subgroups were created according to their therapy adherence: one with long-term blood Phe levels in the therapeutic range (<600 µmol/L), and one with suboptimal blood Phe levels. Renal function and metabolic parameters were collected over 10 years. Kidney function parameters were compared between the two groups and associations between blood Phe levels and kidney function were tested. Results: After 10 years, serum creatinine levels (p = 0.369) and estimated glomerular filtration rate (eGFR) (p = 0.723) did not change significantly from baseline in the good therapeutic group. The suboptimal therapeutic group’s eGFR decreased in the same period (from 110.4 ± 14 mL/min/1.73 m² to 94.2 ± 16 mL/min/1.73 m², p = 0.017). At 10 years, the suboptimal therapeutic group had an increased serum creatinine level (81 ± 14.4 μmol/L vs. 71.5 ± 13 μmol/L, p = 0.038), and a decreased eGFR (94.2 ± 16 mL/min/1.73 m² vs. 103.3 ± 13 mL/min/1.73 m²p = 0.031) compared to the good adhering group. Significant negative correlation between Phe levels and eGFR (r = −0.41, p = 0.008) was observed. Conclusion: Long-term suboptimal therapy adherence in PKU patients with high blood Phe levels may lead to deterioration in kidney function.

Health-related quality of life in a european sample of adults with early-treated classical PKU

BackgroundPhenylketonuria (PKU) is a rare inborn error of metabolism affecting the catabolism of phenylalanine (Phe). To date, findings regarding health-related quality of life (HRQoL) in adults with early-treated classical PKU are discrepant. Moreover, little is known about metabolic, demographic, and cognitive factors associated with HRQoL. Hence, we aimed to investigate HRQoL and its association with demographic, metabolic, and cognitive characteristics in a large European sample of adults with early-treated classical PKU.ResultsThis cross-sectional study included 124 adults with early-treated classical PKU from Hungary, Italy, Spain, Switzerland, and Turkey. All participants prospectively completed the PKU quality of life questionnaire (PKU-QoL), a questionnaire specifically designed to evaluate the impact of PKU and its treatment on HRQoL in individuals with PKU. In addition, information about Phe levels (concurrent and past year), demographic (age and sex), and cognitive variables (intelligence quotient, IQ) were collected. Most domains revealed little or no impact of PKU on HRQoL and more than three-quarters of the patients rated their health status as good, very good, or excellent. Nevertheless, some areas of concern for patients were identified. Patients were worried about the guilt that they experience if they do not adhere to the dietary protein restriction and they were most concerned about high Phe levels during pregnancy. Further, tiredness was the most affected symptom, and the supplements’ taste was considered a main issue for individuals with PKU. The overall impact of PKU on HRQoL was higher in women (U = 1315.5, p = .012) and in adults with a lower IQ (rs = − 0.448, p = .005). The overall impact of dietary protein restriction was higher in adults with higher concurrent Phe levels (rs = 0.272, p = .007) and higher Phe levels during the past year (rs = 0.280, p = .009).ConclusionThe impact of PKU on most domains assessed in the PKU-QoL was considered to be low. These results likely reflect the successful implementation of the newborn screening resulting in the prevention of severe adverse long-term outcomes. However, a particular clinical focus should be given to patients with lower IQ, higher Phe levels, and women, as these variables were associated with a lower HRQoL.

Increased cytokine levels induced by high phenylalanine concentrations in late diagnosis PKU patients compared to early diagnosis: Anti-inflammatory effect of L-carnitine.

Phenylketonuria (PKU) was the first genetic disease to have an effective therapy, which consists of phenylalanine intake restriction. However, there are patients who do not adhere to treatment and/or are not submitted to neonatal screening. PKU patients present L-carnitine (L-car) deficiency, compound that has demonstrated an antioxidant and anti-inflammatory role in metabolic diseases. This study evaluated the effect caused by exposure time to high Phe levels in PKU patients at early and late diagnosis, through pro- and anti-inflammatory cytokines, as well as the L-car effect in patients under treatment. It was observed that there was a decrease in phenylalanine levels in treated patients compared to patients at diagnosis, and an increase in L-car levels in the patients under treatment. Inverse correlation between Phe versus L-car and nitrate plus nitrite versus L-car in PKU patients was also showed. We found increased proinflammatory cytokines levels: interleukin (IL)-1β, interferons (IFN)-gamma, IL-2, tumor necrosis factor (TNF)-alpha, IL-8 and IL-6 in the patients at late diagnosis compared to controls, and IL-8 in the patients at early diagnosis and treatment compared to controls. Increased IL-2, TNF-alpha, IL-6 levels in the patients at late diagnosis compared to early diagnosis were shown, and reduced IL-6 levels in the treated patients compared to patients at late diagnosis. Moreover, it verified a negative correlation between IFN-gamma and L-car in treated patients. Otherwise, it was observed that there were increased IL-4 levels in the patients at late diagnosis compared to early diagnosis, and reduction in treated patients compared to late diagnosed patients. In urine, there was an increase in 8-isoprostane levels in the patients at diagnosis compared to controls and a decrease in oxidized guanine species in the treated patients compared to the diagnosed patients. Our results demonstrate for the first time in literature that time exposure to high Phe concentrations generates a proinflammatory status, especially in PKU patients with late diagnosis. A pro-oxidant status was verified in not treated PKU patients. Our results demonstrate the importance of early diagnosis and prompt start of treatment, in addition to the importance of L-car supplementation, which can improve cellular defense against inflammation and oxidative damage in PKU patients.

Abstract 2865: IL4I1, IDO1 and other amino acid-metabolizing enzymes in high-grade serous ovarian cancer

Abstract Ovarian cancer is among the most lethal malignancies in women, and breakthrough immunotherapies including anti-PD-1/PD-L1 and anti-CTLA4 have thus far not been able to significantly ameliorate patient outcomes. In various tumor types, amino acid-metabolizing enzymes such as indoleamine 2,3-dioxygenase 1 (IDO1) and arginase 1 (ARG1) have been found to be among the culprits responsible for generation of an immunosuppressive tumor microenvironment. More recently, interleukin 4 induced 1 (IL4I1) was put forward as a promising anticancer drug target, whereas its expression may also contribute to resistance against IDO1 inhibition. Similar to IDO1, IL4I1 can metabolize tryptophan (Trp) resulting in the formation of AhR agonists, although phenylalanine (Phe) and tyrosine (Tyr) are also major substrates of IL4I1. Plasma and ascites (i.e., peritoneal fluid buildup) were collected from advanced-stage high-grade serous ovarian cancer (HGSOC) patients to determine whether aberrant metabolism by amino acid-metabolizing enzymes occurs in these patients and to evaluate ascites as a potential source of biomarkers related to these enzymes. Activity of the enzymes was indirectly determined through measurement of relevant amino acids and metabolites by targeted metabolomics using LC-MS/MS, while levels of secreted IL4I1 were determined by ELISA. Amino acid, metabolite and enzyme concentrations were compared to healthy control subjects and were examined for correlations with clinicopathological characteristics and clinical outcomes. Pleural effusions from non-small cell lung cancer patients were included to evaluate whether the results could be extended towards another type of cancer-related fluid buildup. Metabolism of Trp was significantly elevated in HGSOC patients compared to control subjects, likely attributable to increased IDO1 expression. Kynurenine (Kyn) levels and Kyn/Trp ratios were higher in ascites compared to plasma samples, demonstrating the value of utilizing this fluid for biomarker detection. Whereas elevated metabolism of Trp by IL4I1 could not be detected in the patients, high levels of Phe- and Tyr-derived metabolites associated with IL4I1 activity were found in their ascites. Levels of these metabolites significantly correlated with the concentration of IL4I1. Moreover, enhanced metabolism of Phe and Tyr correlated with disease stage, suggesting a role for IL4I1 in HGSOC progression. Elevated levels of IL4I1-associated metabolites were also found in the pleural effusions of a subset of non-small cell lung cancer patients, demonstrating that enhanced IL4I1 activity is not limited to ovarian cancer ascites. In conclusion, our results suggest that IL4I1 may be involved in HGSOC progression, indicating this enzyme as a potential therapeutic target. The levels of IL4I1- and IDO1-generated metabolites in ascites may additionally serve as valuable diagnostic or predictive biomarkers. Citation Format: Yvonne Grobben, Judith E. den Ouden, Cristina Aguado, Anne M. van Altena, Aletta D. Kraneveld, Guido J. Zaman. IL4I1, IDO1 and other amino acid-metabolizing enzymes in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2865.

Evaluation of the Consumption of Fruits and Vegetables by Phenylketonurics in the Metabolic Control of Phenylalanine: An Integrative Review.

Phenylketonuria (PKU) is an autosomal recessive disease caused by variants in the gene that encodes phenylalanine hydroxylase (PAH), limiting the metabolism of phenylalanine (Phe). When PAH activity is absent or hindered, Phe is not converted to tyrosine, leading to an accumulation of Phe in the blood, which can cause serious neurological complications. Once PKU is diagnosed, treatment should be started immediately, and the basis for this is dietary restriction of foods with high levels of Phe, associated with the use of protein substitutes and intake of foods with low protein content. This restriction accompanies patients throughout their lives, making their diets unpalatable and monotonous, which represents a major challenge for health professionals and patients, considering that these factors favor food transgression. In this context, the objective of this work was to carry out an integrative review based on evidence regarding the intake of fruits and vegetables, by phenylketonurics, taking into account the greater or lesser tolerance to Phe. Since, some researchers have dedicated themselves to evaluating the biochemical effect of unrestricted consumption of fruits and vegetables at PKU, unifying the information in this regard. It was observed that the intake of vegetable protein by patients with PKU has shown to be promising since the studies indicate that the intake of these proteins does not present adverse effects to the metabolic control of the Phe.

A culture model for the assessment of phenylalanine neurotoxicity in phenylketonuria

ObjectivePhenylketonuria (PKU) is caused by a specific mutation of the phenylalanine hydroxylase (PAH) gene. The deficiency of PAH results in high phenylalanine levels (Phe), low tyrosine levels (Tyr), and reduced catecholamine neurotransmitters. The majority of PKU patients, if untreated, develop severe mental retardation. The specific contribution of high Phe and low Tyr levels in mental retardation is largely unknown. In this study, we used organic hippocampal slice cultures in an optimized medium as an adequate culture model to decipher the precise role of high Phe and low Tyr levels on synaptic and glial integrity in PKU. The hippocampus is closely related to learning and memory and reduced catecholamine neurotransmitter levels can be neglected since these neurotransmitters do not derive from the hippocampus. Cultures exposed to physiological concentrations of Phe were compared with cultures exposed to doses of Phe/Tyr, as in the cerebral fluid of PKU patients.MethodsUsing capillary western blot analysis and immunohistochemistry, followed by quantitative image analysis, we tested the expression of various pre- and postsynaptic proteins (PSD95, synaptopodin, SNAP25, synaptophysin), glial cell markers (GFAP, Iba1, P2Y12, CD68, C3b), and the morphology of glial cells.ResultsWe found a downregulation of the postsynaptic protein PSD95 and the presynaptic protein SNAP25 in the presence of high/low Phe/Tyr levels after 3 weeks, which, then however, recovered after 6 weeks in culture. Furthermore, no change in the expression pattern of glial proteins was observed.ConclusionOur results show that high Phe levels/low Tyr levels alone are unlikely to substantially contribute to mental retardation in PKU. The direct neurotoxic potency of high Phe/low Tyr concentrations is almost negligible since the effects are transient. The transient character in the presence of unchanged levels of high Phe/low Tyr points to a role of reduced catecholamine derivate neurotransmitters, rather than of high Phe/low Tyr levels in PKU.

Endoplasmic reticulum stress in leukocytes from phenylketonuric patients

Abstract Objectives Phenylketonuria (PKU) is a proteinopathy due to the deficiency of phenylalanine hydroxylase (PAH) enzyme. The pathological elevation of phenylalanine (Phe) and its metabolites in PKU is linked to neurological hallmarks and mental disabilities. The aim of this study was to examine the hypothesis that high levels of Phe caused endoplasmic reticulum (ER) stress in PKU patients. Methods We primarily evaluated ER stress markers glucose-regulated protein78 (GRP78) and C/-EBP homologous protein (CHOP), and thiobarbituric acid-reactive substances (TBARS) as a biomarker of oxidative stress in leukocytes and correlated it with blood Phe values from patients with PKU. Patients in this study were selected from individuals who were diagnosed with PKU as a result of the national neonatal screening program and undergone treatment at our university hospital. The subjects were divided into four groups: healthy controls, patients with hyperphenylalaninemia (HPA), BH4-responsive patients with PKU and patients with classic PKU. GRP78, CHOP and TBARS levels were estimated in leukocytes isolated from whole blood of subjects, Phe and tyrosine levels were determined in plasma. Results The levels of Phe in BH4-responsive PKU and classic PKU groups were statistically higher as compared to healthy controls, and Phe levels were higher in classic PKU compared to HPA group. CHOP levels were elevated by 35.3% in BH4-responsive group compared to control. GRP78, CHOP and TBARS showed no statistical differences between control and patient groups. GRP78 was also negatively correlated with Phe levels. Conclusions These results suggested that blood Phe concentrations might not be associated to ER stress in white blood cells obtained from the PKU patient groups under treatment.

Deregulation of phenylalanine biosynthesis evolved with the emergence of vascular plants.

Phenylalanine (Phe) is the precursor of essential secondary products in plants. Here we show that a key, rate-limiting step in Phe biosynthesis, which is catalyzed by arogenate dehydratase, experienced feedback de-regulation during evolution. Enzymes from microorganisms and type-I ADTs from plants are strongly feedback-inhibited by Phe, while type-II isoforms remain active at high levels of Phe. We have found that type-II ADTs are widespread across seed plants and their overproduction resulted in a dramatic accumulation of Phe in planta, reaching levels up to 40 times higher than those observed following the expression of type-I enzymes. Punctual changes in the allosteric binding site of Phe and adjacent region are responsible for the observed relaxed regulation. The phylogeny of plant ADTs evidences that the emergence of type-II isoforms with relaxed regulation occurred at some point in the transition between nonvascular plants and tracheophytes, enabling the massive production of Phe-derived compounds, primarily lignin, a hallmark of vascular plants.

Incorporation of TePhe into Expressed Proteins is Minimally Perturbing.

Tellurium is a versatile heavy chalcogen with numerous applications in chemical biology, providing valuable probes in mass cytometry, fluorescence imaging and structural biology. L-Tellurienylalanine (TePhe) is an analogue of the proteinogenic amino acid L-phenylalanine (Phe) in which the phenyl side chain has been replaced by a 5-membered tellurophene moiety. High incorporation level of TePhe in expressed proteins at defined sites is expected to facilitate studies in proteomics, protein NMR spectroscopy, and structure elucidation. As a model we chose immunoglobulin-binding Protein G, B1 domain (GB1) to validate TePhe as a suitable structural analogue for Phe. We demonstrate that approximately 1 in 2 of all Phe sites within GB1 can be substituted with TePhe through expression in standard non-Phe-auxotrophic E. coli in Phe-deficient media containing glyphosate, an inhibitor of aromatic amino acid biosynthesis. The TePhe content of the GB1 sample can be further increased to 85 % through HPLC. Using NMR and CD spectroscopy, we confirm that the Phe-to-TePhe substitution has negligible impact on the global structure and stability of GB1.

Dynamic variations in serum amino acid and the related gene expression in liver, ovary, and oviduct of pigeon during one egg-laying cycle

The present study was carried to investigate dynamic variations in serum amino acid (AA) contents and the relative mRNA abundance of the AA transporters and AA synthesis-related enzymes in liver, ovary and oviduct of pigeons during one egg-laying cycle (ELC). In experiment 1, seventy laying pigeons (American Silver King) were randomly divided into 14 groups by different days of one ELC (DELC) and arranged as a 2 × 7 factorial design, which included 2 ages (6-mo-old or 12-mo-old) and 7 DELCs. For experiment 2, 35 six-mo-old laying pigeons (American Silver King) were randomly divided into 7 groups by different DELCs and immediately treated with a 12-h fasting. Dynamic variations in serum AAs were detected during one ELC, characterized by high levels of Lys, Met, Leu, Phe, Tyr, Asp, Ser, Glu, Ala, and TAA on day 1 (D1) of one ELC (P < 0.05). Fasting caused obvious decreases in serum levels of Leu, Ile, Val, Phe, Tyr, and TAA from day 2 (D2) to day 7 (D7) (P < 0.05). Relative organ weights of ovary and oviduct increased to the peak values on day 13 (D13) (P < 0.05). Serum calcium decreased to the lowest level on day 4 (D4) (P < 0.05) and serum total triglyceride was kept in a high level on D1, D7, day 10 (D10), and D13 (P < 0.05). Relative mRNA expression of the AA synthesis genes and the AA transport genes exhibited different variation patterns in liver, ovary and oviduct, but Pearson correlation test showed the percentage of positive r values with significant differences were much higher in oviduct than those in liver or ovary. In conclusion, dynamic variations of serum AAs during one ELC were positively related with the expression of the AA transport genes and AA synthesis genes in oviduct, suggesting the upregulated serum AAs might be necessary to meet the AAs requirement for egg white formation in pigeon.

Phenylketonuric patients represent their disease.

Background Phenylketonuria (PKU) is a metabolic disorder resulting in high phenylalanine (Phe) blood concentrations due to the deficiency of the hepatic enzyme Phe hydroxylase. High Phe levels are currently treated with diet, thus avoiding mental retardation, psychomotor delay, etc. The aim of this study was to find out the self-presentation of the disease by the patients. Methods A total number of 110 patients self-represented their disease: food allergy (Phe allergy) n = 34/110 (30.9%), health problems n = 31/110 (28.2%), severe health problems n = 26/110 (23.6%), very severe health problems n = 19/110 (17.3%). The Wechsler Intelligence Scale for Children (WISC III) psychometric test was utilized for the evaluation of IQ scores of each participant. A special questionnaire was used focusing on quality of life (QL), social discrimination (SD) and anxiety or depression (AD). Results IQ scores were found to be higher in food allergy self-represented patients than those of the other tested groups. The lowest IQ scores were observed in those who represented very severe disease. QL, SD and AD were not observed in the food allergy groups. On the contrary, those who self-presented as very severe diseased patients felt high a disturbance of QL, SD and AD. Conclusions The food allergy group seemed to be a very clever excuse for adhering to PKU treatment resulting in high IQ scores and absence of the mentioned upsets. In contrast, in the other groups of patients' IQ scores were found to be lower than that of food allergy group. Damage of QL, SD, AD were also apparent.

The significant role of educational status in PKU patients: the beneficial effect of psychological support in depression.

Classical Phenylketonuria (PKU) is a metabolic disease characterized by high phenylalanine (phe) levels in blood and brain. PKU patients are commonly treated with low phe diet supplemented with amino acid free formula. High Phe levels minimize brain tryptophan concentration, the pressure of serotonin, which is responsible for the appearance of depression symptoms. Both amino acids share the same pathway for entering CNS via BBB. Aimed to determine the effect of psychological support on different education status depressed PKU patients via adherence to their diet. PKU patients (n = 110) were divided into groups according to their education status: Primary school, High school, University degree. All patients were tasted with a Patient Health Questionnaire (PHQ-9) standardized for Greek population. Psychological support was performed in every depressed patient ones per two weeks for three successive months under the same conditions. Phe blood levels were measured before psychological support and every 15-20 days till the end of the study. Only 2/110 (1.8%) participance had finished Primary school and were healthy. 72/110 (65.5%) High School, out of them 29 were depressed and 36/110 (32.7%) achieved a University degree, only 6 suffered from depression. High phe blood levels were measured in the depressed patients, which dropped near to normal after the end of their psychological support. Referring to depression symptoms, all participance except one presented amelioration of their mood. Psychological support is beneficial on depressed PKU patients graduated with High School or University degree via adherence to their special diet.

Arterial stiffness assessment in patients with phenylketonuria.

In patients with phenylketonuria (PKU) compliant to diet greater tendency to overweight and higher inflammatory biomarkers levels than controls were reported. Although this could lead to atherogenesis, the elastic properties of large arteries in PKU patients have never been assessed. The aim of this study was to assess arterial stiffness measured by applanation tonometry in PKU patients compared to healthy controls.We carried out a cross-sectional study in 41 PKU patients (range age: 6-50 years old) and 41 age- and gender-matched healthy controls. Evaluated data included pharmacological treatment with sapropterin, clinical, and biochemical parameters. Aortic stiffness was assessed noninvasively by applanation tonometry measuring central blood pressure, aortic augmentation index (Aix@HR75), augmentation pressure (AP), and pulse wave velocity (PWV).We found higher PWV in classic PKU patients (6.60 m/second vs 5.26 m/second; P: .044). Percentage of PKU patients with PWV above 90 percentile was higher than controls (14.63% vs 2.32%; P: .048). A positive relationship was observed between the annual Phe median and PWV (r: 0.496; P: .012). PKU subjects with lower Phe tolerance showed more body weight (67.6 kg vs 56.8 kg; P: .012) and more PWV than those with higher Phe tolerance (6.55 m/second vs 5.42 m/second; P: .044).Our data show increased aortic stiffness in PKU patients, measured by applanation tonometry, when compared to healthy controls. Higher Phe levels are associated with a bigger PWV increase, which is not present in those subjects compliant to diet or under sapropterin treatment. These results could have marked effects in both research and clinical daily practice for a proper evaluation of cardiovascular risk in PKU subjects.

Subtle visuomotor deficits and reduced benefit from practice in early treated phenylketonuria

ABSTRACTIntroduction: Phenylketonuria (PKU) is a rare metabolic disease that causes slight-to-severe neurological symptoms. Slow performance has been observed in PKU but the influence of high-order (i.e., not purely motor) deficits and of temporary variations of the phenylalanine (Phe) level on this slowness has not been fully corroborated as yet. Response speed and the effect of motor practice during the performance of a visuomotor coordination task were measured, in a group of patients with early-treated phenylketonuria (ET PKU). Method: We compared the performance of a group of early-treated PKU patients with ages ranging from 11 to 25 years and a control group of healthy volunteers on a computerized visuomotor task. Participants performed rapid movements towards one of five response buttons, as indicated by a visual stimulus that could appear in five different positions on a computer screen. The results of our visuomotor task were correlated with neurobiological data (Phe levels) and with neuropsychological measures of motor (finger tapping) and executive functions (Stroop task). Results: The ET PKU group showed slower responses than the control group. Furthermore, an absence of a practice effect (i.e., faster response times at the end of the study) was found in the PKU group but not in the control group. Our results also revealed that this absence of practice effect correlated with higher Phe levels on the testing day with respect to the average Phe level of the previous 12 months and, although weakly, with performance on the Stroop task. Conclusions: This pattern of results indicates slower visuomotor performance and a less beneficial effect of practice in ET PKU. The correlations found among our visuomotor measures, the same-day Phe level, and the Stroop test may reflect the negative effects of dopamine reduction in brain areas involved in motor control, selective attention, and learning.