High Phenylalanine Concentrations Research Articles

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.

Two-year interim safety and efficacy of pegvaliase in Japanese adults with phenylketonuria

Phenylketonuria (PKU) is an inborn error of metabolism caused by deficiency of phenylalanine hydroxylase, resulting in high blood phenylalanine (Phe) concentrations with potential for impaired neurocognition. Pegvaliase, a pegylated recombinant phenylalanine ammonia lyase that metabolizes Phe, is approved for use in adults with PKU and high blood Phe despite prior management. In the Phase 3 PRISM studies conducted in the United States, pegvaliase induction/titration/maintenance dosing led to clinically meaningful and statistically significant blood Phe reductions versus placebo, with a manageable safety profile. Here we report the primary endpoint, change in blood Phe levels from baseline to Week 52, and 2-year interim efficacy and safety results (to Week 144; data cut-off March 31, 2022) of an ongoing, open-label study in a Japanese PKU population (JapicCTI-194,642). Participants were 12 adults with PKU from Japan aged 18–70 years with blood Phe levels >600 μmol/L. In Part 1, participants received subcutaneous 2.5 mg pegvaliase once weekly for 4 weeks (induction), followed by titration up to 20 mg/day, then dose adjustment to a maximum 40 mg/day to achieve blood Phe efficacy (≤360 μmol/L); this maintenance dose was continued to Week 52. In Part 2, participants continued pegvaliase with dose adjustments up to a maximum 60 mg/day for up to 168 weeks. Among 11 participants evaluable for efficacy, mean (standard deviation) blood Phe concentration decreased from 1025.9 (172.7) μmol/L at baseline to 448.3 (458.8) μmol/L at Week 52 (mean 57.5% decrease). Up to Week 104, all 11 (100%) efficacy-evaluable participants achieved blood Phe levels ≤600 μmol/L, 9 (81.8%) achieved ≤360 μmol/L, and 8 (72.7%) achieved ≤120 μmol/L. All 12 participants reported ≥1 adverse event (AE), most commonly injection site erythema and injection site swelling (n = 10, 83.3% each). The pegvaliase exposure-adjusted AE rate was 23.5 per person-years overall, 41.2 per person-years during induction/titration, and 13.5 per person-years during maintenance. All participants developed pegvaliase-induced antibody responses. There were no AEs leading to discontinuation, no deaths, and no anaphylaxis events. Although interim, these results support the use of pegvaliase in Japanese adults with PKU with elevated blood Phe levels and are consistent with results from the Phase 3 PRISM studies.

Identification of blood cell changes in pediatric oncological patients through Raman spectroscopy

AbstractThis study aimed to use the Raman spectroscopy technique to identify biochemical changes in blood cell samples of healthy, leukemic, and non‐leukemic subjects by principal component analysis (PCA) and to discriminate the groups by partial least squares discriminant analysis (PLS‐DA). For the study, 121 blood samples were collected from healthy children and adolescents among those with leukemia and other types of cancer (non‐leukemics). A volume of 80 μl of blood cells was placed in an aluminum sample holder and submitted to dispersive Raman spectroscopy (laser: 830 nm and 250 mW), with an exposure time of 30 s. A total of 308 Raman spectra were analyzed and indicated significant differences in the bands referred to nucleic acids (671 and 756 cm−1), amino acids (671, 1,215, and 1,544 cm−1), proteins (756, 1,215, 1,430, 1,531, and 1,548 cm−1), β‐carotene (1,531 cm−1), and cytochrome c (756 and 1,371 cm−1), showing higher intensity in normal samples. The analysis of the PCA variables (PCs) showed that there was a higher concentration of cytochrome c (633, 749, 855, 1,004, 1,127, 1,212, 1,370, 1,433, 1,531, and 1,614 cm−1), in the normal samples, and a higher concentration of phenylalanine (1,004 cm−1) was observed in the leukemic samples with statistically significant (ANOVA, p < 0.05). Discriminant analysis by PLS‐DA model classified the spectra into the groups normal (healthy), leukemic, and non‐leukemic with accuracy of 67.5%; when considering normal versus cancer, the accuracy increased to 98.3%, with sensitivity of 100% and specificity of 87.8%. Results demonstrated the applicability of Raman spectroscopy for analyzing biochemical compounds in blood cells, thus identifying the spectral differences between the groups normal, leukemic, and non‐leukemic (with other types of cancer). However, it presented a low accuracy due to classification errors when discriminating between the groups leukemic and non‐leukemic.

Aspartame and Phenylketonuria: an analysis of the daily phenylalanine intake of aspartame-containing drugs marketed in France

BackgroundPhenylketonuria (PKU) is a rare genetic metabolic disorder in which especially high phenylalanine (Phe) concentrations cause brain dysfunction. If untreated, this brain dysfunction results in severe microcephaly, intellectual disability, and behavioral problems. Dietary restriction of Phe is the mainstay of PKU treatment, with long-term successful outcomes. Aspartame, an artificial sweetener sometimes added into medications, is metabolized in the gut into Phe. Then, patients suffering from PKU on a Phe-restricted diet should avoid consumption of aspartame. The aim of our study was to evaluate the number of drugs containing aspartame and/or Phe as an excipient, and to quantify their corresponding Phe intake.MethodsThe list of drugs marketed in France containing aspartame and/or Phe was established using a national medication database called “Theriaque”. For each drug, the corresponding daily Phe intake was calculated according to age and weight and was distributed into 3 categories: high (> 40 mg/d), medium (10 to 40 mg/d) and low (< 10 mg/d) Phe intake.ResultsThe number of drugs containing Phe or its precursor aspartame remained very limited (n = 401). Among the aspartame containing drugs, Phe intakes were significant (medium or high) for only half of them whereas there were negligible for the others. Furthermore, these medications with a significant Phe intake were limited to few pharmaceutical classes (mainly antiinfectives agents, analgesics, and drugs for nervous system), and within these classes the drugs were limited to a small number of molecules, including principally amoxicillin, amoxicillin + clavulanic acid and paracetamol/ acetaminophen.DiscussionIn situations requiring the use of these molecules, we propose as an alternative, the use of an aspartame-free form of these molecules or a form with a low Phe intake. If it is not possible, we propose as second-line the use of another antibiotics or analgesics. Finally, we have to remember the benefits-risk balance to use medications containing significant Phe intake in PKU patients. Indeed, it may be better to use a Phe containing medication in the absence of an aspartame-free form of this drug rather than to leave a person with PKU without treatment.

Risk of Developing Insulin Resistance in Adult Subjects with Phenylketonuria: Machine Learning Model Reveals an Association with Phenylalanine Concentrations in Dried Blood Spots.

Phenylketonuria (PKU) is an autosomal recessive inborn error of metabolism where high phenylalanine (Phe) concentrations cause irreversible intellectual disability that can be prevented by newborn screening and early treatment. Evidence suggests that PKU subjects not adherent to treatment could be at risk of insulin resistance (IR). We studied how Phe concentrations (PheCs) relate to IR using machine learning (ML) and derived potential biomarkers. In our cross-sectional study, we analyzed subjects with neonatal diagnoses of PKU, grouped as follows: 10 subjects who adhered to treatment (G1); 14 subjects who suspended treatment (G2); and 24 control subjects (G3). We analyzed plasma biochemical variables, as well as profiles of amino acids and acylcarnitines in dried blood spots (DBSs). Higher PheCs and plasma insulin levels were observed in the G2 group compared to the other groups. Additionally, a positive correlation between the PheCs and homeostatic measurement assessments (HOMA-IRs) was found, as well as a negative correlation between the HOMA-Sensitivity (%) and quantitative insulin sensitivity check index (QUICKI) scores. An ML model was then trained to predict abnormal HOMA-IRs using the panel of metabolites measured from DBSs. Notably, ranking the features' importance placed PheCs as the second most important feature after BMI for predicting abnormal HOMA-IRs. Our results indicate that low adherence to PKU treatment could affect insulin signaling, decrease glucose utilization, and lead to IR.

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.

High phenylalanine concentrations induce demyelination and microglial activation in mouse cerebellar organotypic slices

Phenylketonuria (PKU) is an inborn error of metabolism. Mutations in the enzyme phenylalanine hydroxylase (PAH)-encoding gene lead to a decreased metabolism of the amino acid phenylalanine (Phe). The deficiency in PAH increases Phe levels in blood and brain. Accumulation of Phe can lead to delayed development, psychiatric problems and cognitive impairment. White matter (WM) damage is a neuropathological hallmark of PKU and can be seen even in early detected and treated PKU patients. The mechanisms linking high Phe concentrations to WM abnormalities remain unclear. We tested the effects of high Phe concentrations on myelin in three in vitro models of increasing complexity: two simple cell culture models and one model that preserves local brain tissue architecture, a cerebellar organotypic slice culture prepared from postnatal day (P) 8 CD-1 mice. Various Phe concentrations (0.1–10 mM) and durations of exposure were tested. We found no toxic effect of high Phe in the cell culture models. On the contrary, the treatment promoted the maturation of oligodendrocytes, particularly at the highest, non-physiological Phe concentrations. Exposure of cerebellar organotypic slices to 2.4 mM Phe for 21 days in vitro (DIV), but not 7 or 10 DIV, resulted in a significant decrease in myelin basic protein (MBP), calbindin-stained neurites, and neurites co-stained with MBP. Following exposure to a toxic concentration of Phe, a switch to the control medium for 7 days did not lead to remyelination, while very active remyelination was seen in slices following demyelination with lysolecithin. An enhanced number of microglia, displaying an activated type morphology, was seen after exposure of the slices to 2.4 mM Phe for 10 or 21 DIV. The results suggest that prolonged exposure to high Phe concentrations can induce microglial activation preceding significant disruption of myelin.

Epidemiology of Phenylketonuria Disease in Jordan: Medical and Nutritional Challenges.

Background: Phenylketonuria (PKU) is the most frequent inborn error in amino acid metabolism caused by a deficiency of the phenylalanine hydroxylase enzyme (PAH). If PKU is left untreated, high concentrations of phenylalanine (Phe) accumulate in the blood, leading to severe brain dysfunction, neurodevelopmental, behavioral and psychological problems. Data concerning the epidemiology of PKU in Jordan are limited. The main objectives of our study were to determine the prevalence of PKU in Jordan, analyze the PKU phenotypes, and identify major challenges in providing dietary management to PKU patients. Methods: Data were collected utilizing the medical records of PKU patients attending the PKU clinic at the Ministry of Health in Amman, Jordan, between 2008 and 2021. Results: The total number of patients diagnosed with PKU was 294. The prevalence of PKU was estimated to be 1/5263. Most patients were Jordanians (90.8%), and 9.2% were non-Jordanians. More than half of the patients (56%) were diagnosed through the national newborn screening (NBS) program. Regarding the phenotypes of PKU, 46.6% had moderate PKU, whereas 42.9% had the classic type of PKU and only 8 (2.7%) had cofactor Tetrahydrobiopterin (BH4) deficiency (atypical PKU). According to the age of diagnosis, 66% of patients were diagnosed more than 30 days post-birth. Consanguinity was found in 87.4% of patients, and the majority of patients, 218 (74.2%), had first-degree consanguinity. The most common complication was mental retardation (31%). Most patients were committed to dietary management (83%) and developed fewer complications. Conclusion: In our study, we demonstrated the importance of the NBS program in the early identification and diagnosis of new PKU cases which allows the initiation of treatment and dietary management to prevent severe complications of PKU in Jordan.

The Impact of the Quality of Nutrition and Lifestyle in the Reproductive Years of Women with PKU on the Long-Term Health of Their Children.

A woman’s nutritional status before and during pregnancy can affect the health of her progeny. Phenylketonuria (PKU), a rare disorder causing high blood and brain phenylalanine (Phe) concentrations, is associated with neurocognitive disability. Lifelong treatment is mainly dietetic with a Phe-restricted diet, supplemented with a low-Phe protein substitute. Treatment adherence commonly decreases in adolescence, with some adults ceasing dietary treatment. In maternal PKU, elevated blood Phe is harmful to the fetus so a strict Phe-restricted diet must be re-established preconception, and this is particularly difficult to achieve. A woman’s reproductive years introduces an opportunity to adopt healthier behaviours to prepare for successful pregnancies and positive health outcomes for both themselves and their children. Several factors can influence the health status of women with PKU. Political, socioeconomic, and individual food and lifestyle choices affect diet quality, metabolic control, and epigenetics, which then pre-condition the overall maternal health and long-term health of the child. Here, we reflect on a comprehensive approach to treatment and introduce practical recommendations to optimize the wellbeing of women with PKU and the resultant health of their children.

Untreated PKU patients without intellectual disability: SHANK gene family as a candidate modifier

Phenylketonuria (PKU) is an inborn error of metabolism caused by variants in the phenylalanine hydroxylase (PAH) gene and it is characterized by excessively high levels of phenylalanine in body fluids. PKU is a paradigm for a genetic disease that can be treated and majority of developed countries have a population-based newborn screening. Thus, the combination of early diagnosis and immediate initiation of treatment has resulted in normal intelligence for treated PKU patients. Although PKU is a monogenic disease, decades of research and clinical practice have shown that the correlation between the genotype and corresponding phenotype is not simple at all. Attempts have been made to discover modifier genes for PKU cognitive phenotype but without any success so far.We conducted whole genome sequencing of 4 subjects from unrelated non-consanguineous families who presented with pathogenic mutations in the PAH gene, high blood phenylalanine concentrations and near-normal cognitive development despite no treatment. We used cross sample analysis to select genes common for more than one patient. Thus, the SHANK gene family emerged as the only relevant gene family with variants detected in 3 of 4 analyzed patients. We detected two novel variants, p.Pro1591Ala in SHANK1 and p.Asp18Asn in SHANK2, as well as SHANK2:p.Gly46Ser, SHANK2:p.Pro1388_Phe1389insLeuPro and SHANK3:p.Pro1716Thr variants that were previously described. Computational analysis indicated that the identified variants do not abolish the function of SHANK proteins. However, changes in posttranslational modifications of SHANK proteins could influence functioning of the glutamatergic synapses, cytoskeleton regulation and contribute to maintaining optimal synaptic density and number of dendritic spines.Our findings are linking SHANK gene family and brain plasticity in PKU for the first time. We hypothesize that variant SHANK proteins maintain optimal synaptic density and number of dendritic spines under high concentrations of phenylalanine and could have protective modifying effect on cognitive development of PKU patients.

Phenylketonuria.

Phenylketonuria (PKU; also known as phenylalanine hydroxylase (PAH) deficiency) is an autosomal recessive disorder of phenylalanine metabolism, in which especially high phenylalanine concentrations cause brain dysfunction. If untreated, this brain dysfunction results in severe intellectual disability, epilepsy and behavioural problems. The prevalence varies worldwide, with an average of about 1:10,000 newborns. Early diagnosis is based on newborn screening, and if treatment is started early and continued, intelligence is within normal limits with, on average, some suboptimal neurocognitive function. Dietary restriction of phenylalanine has been the mainstay of treatment for over 60 years and has been highly successful, although outcomes are still suboptimal and patients can find the treatment difficult to adhere to. Pharmacological treatments are available, such as tetrahydrobiopterin, which is effective in only a minority of patients (usually those with milder PKU), and pegylated phenylalanine ammonia lyase, which requires daily subcutaneous injections and causes adverse immune responses. Given the drawbacks of these approaches, other treatments are in development, such as mRNA and gene therapy. Even though PAH deficiency is the most common defect of amino acid metabolism in humans, brain dysfunction in individuals with PKU is still not well understood and further research is needed to facilitate development of pathophysiology-driven treatments.

STIMULATION OF GROWTH AND OIL PRODUCTION IN CUMIN PLANT

A pot experiment was carried out during two successive seasons (2017/ 2018 and 2018/2019) at Medicinal and Aromatic Plants Research Department in Dokki. The aim of this work was to study the effect of foliar application of phenylalanine (Phe) and p -nitro phenylacetic acid (PNPAA) each of them alone at (0, 50,100 and 150 ppm) on cumin (Cuminum cyminum L.) plant growth, fruits yield, volatile oil production and its major chemical constituents. In general results indicated that, the foliar application of phenylalanine or p-nitrophenylacetic acid significantly increased vegetative growth expressed as (plant height, number of branches per plant) and produced higher fruits yield (g)/plant as well as volatile oil percentage and oil yield compared with control in the two seasons. Moreover, the highest values were obtained from phenylalanine or p-nitrophenylacetic acid at 150 ppm. Cumin plants showed more effective response to p-nitrophenylacetic acid (PNPAA) than phenylalanine (Phe). As for GLC analysis, the results showed that in general the highest percentage of p -menth-1-en7-ol and cumin aldehyde (p -isopropylbenzaldehyde) the main constituents in the volatile oil achieved with the treatment p-nitrophenylacetic acid at 150 ppm. The high concentration of phenylalanine and p-nitrophenylacetic acid (150 ppm) had significant increments in total phenols, total flavonoids and antioxidant activity compared with control. There was a significant increase in phenylalanine ammonia-lyase (PAL) activity compared to control. Also, there was an increment in IAA, GA3 and low level of ABA. It was observed that p -nitrophenylacetic acid (150 ppm) was superior to phenylalanine (150 ppm) in all afore mentioned characters

Immune Activation and Anemia Are Associated with Decreased Quality of Life in Patients with Solid Tumors.

Anemia often coincides with depression and impaired quality of life (QoL) in cancer patients. Sustained immune activation can lead to the development of anemia. Furthermore, it also may go along with changes in tryptophan and phenylalanine metabolism. The aim of our pilot study was to study the relationship between anemia, immune-mediated changes in amino acid metabolism, and the QoL and mood of cancer patients. Questionnaires to measure QoL and depression were completed by 152 patients with solid tumors. Hemoglobin, parameters of immune activation as well as tryptophan and phenylalanine metabolism were determined in the patients’ sera. Anemic patients (51.7%) presented with higher inflammatory markers, and a higher tryptophan breakdown with lower tryptophan concentrations. They reported an impaired QoL and had higher depression scores. Patients with an impaired QoL (65.8%) also suffered from more fatigue and impaired physical, emotional, and social functioning. They, furthermore, presented with higher concentrations of inflammatory markers (C-reactive protein (CRP) and neopterin) as well as higher tryptophan degradation (in men) and higher phenylalanine concentrations (in women). Sixty-one patients (40.1%) had (mostly mild) depression. In these patients, a higher degree of Th1 immune activation was found. The results of our study suggest that cancer-related anemia goes along with an impaired QoL, which is also associated with immune-mediated disturbances of tryptophan and phenylalanine metabolism.

Morning specimen is not representative of metabolic control in Tunisian children with phenylketonuria: a repeated cross-sectional study.

Objective and methods To evaluate variation of capillary phenylalanine concentrations over the day in patients treated for phenylketonuria and the reliability of the morning sample to assess metabolic control, we conducted a repeated cross-sectional study in 25 Tunisian patients on phenylalanine-low diet. For each patient, we collected nine capillary samples over the day. Phenylalanine was dosed by fluorimetry. Results There was a wide variability of phenylalanine concentrations over the day (p<0.001). Compared to morning sample, phenylalanine concentration was significantly lower before lunch (p=0.038), after lunch (p=0.025), before dinner (p<0.001), after dinner (p=0.035) and at 4:00 a.m. (p=0.011). Compared to the 24h sampling, the morning sample had a 68% to identify unbalanced patients. 60% of patients, had peak phenylalanine concentration after the morning. Half of the patients with normal morning phenylalanine concentration had low phenylalanine values over 8-20h. Percentages of high phenylalanine concentrations over the last semester were higher in patients with poor metabolic control over the 24h (21%±43 vs. 0%±9%); p=0.043. Conclusion A single morning sample gives an incomplete information on metabolic control in phenylketonuric patients. Using four pre-prandial samples on the day should be considered as alternative in patients with good metabolic control.

Dried blood spot versus venous blood sampling for phenylalanine and tyrosine

BackgroundThis study investigated the agreement between various dried blood spot (DBS) and venous blood sample measurements of phenylalanine and tyrosine concentrations in Phenylketonuria (PKU) and Tyrosinemia type 1 (TT1) patients.Study designPhenylalanine and tyrosine concentrations were studied in 45 PKU/TT1 patients in plasma from venous blood in lithium heparin (LH) and EDTA tubes; venous blood from LH and EDTA tubes on a DBS card; venous blood directly on a DBS card; and capillary blood on a DBS card. Plasma was analyzed with an amino acid analyzer and DBS were analyzed with liquid chromatography-mass spectrometry. Agreement between different methods was assessed using Passing and Bablok fit and Bland Altman analyses.ResultsIn general, phenylalanine concentrations in LH plasma were comparable to capillary DBS, whereas tyrosine concentrations were slightly higher in LH plasma (constant bias of 6.4 μmol/L). However, in the low phenylalanine range, most samples had higher phenylalanine concentrations in DBS compared to LH plasma. Remarkably, phenylalanine and tyrosine in EDTA plasma were higher compared to all other samples (slopes ranging from 7 to 12%). No differences were observed when comparing capillary DBS to other DBS.ConclusionsOverall agreement between plasma and DBS is good. However, bias is specimen- (LH vs EDTA), and possibly concentration- (low phenylalanine) dependent. Because of the overall good agreement, we recommend the use of a DBS-plasma correction factor for DBS measurement. Each laboratory should determine their own factor dependent on filter card type, extraction and calibration protocols taking the LH plasma values as gold standard.

Untreated PKU Patients without Intellectual Disability: What Do They Teach Us?

Phenylketonuria (PKU) management is aimed at preventing neurocognitive and psychosocial dysfunction by keeping plasma phenylalanine concentrations within the recommended target range. It can be questioned, however, whether universal plasma phenylalanine target levels would result in optimal neurocognitive outcomes for all patients, as similar plasma phenylalanine concentrations do not seem to have the same consequences to the brain for each PKU individual. To better understand the inter-individual differences in brain vulnerability to high plasma phenylalanine concentrations, we aimed to identify untreated and/or late-diagnosed PKU patients with near-normal outcome, despite high plasma phenylalanine concentrations, who are still alive. In total, we identified 16 such cases. While intellectual functioning in these patients was relatively unaffected, they often did present other neurological, psychological, and behavioral problems. Thereby, these “unusual” PKU patients show that the classical symptomatology of untreated or late-treated PKU may have to be rewritten. Moreover, these cases show that a lack of intellectual dysfunction despite high plasma phenylalanine concentrations does not necessarily imply that these high phenylalanine concentrations have not been toxic to the brain. Also, these cases may suggest that different mechanisms are involved in PKU pathophysiology, of which the relative importance seems to differ between patients and possibly also with increasing age. Further research should aim to better distinguish PKU patients with respect to their cerebral effects to high plasma phenylalanine concentrations.

Long-term comparative effectiveness of pegvaliase versus standard of care comparators in adults with phenylketonuria

Phenylketonuria (PKU) is caused by phenylalanine hydroxylase (PAH) deficiency, resulting in high blood and brain Phenylalanine (Phe) concentrations that can lead to impaired brain development and function. Standard treatment involves a Phe-restricted diet alone or in conjunction with sapropterin dihydrochloride in responsive patients. The Food and Drug Administration approved pegvaliase enzyme substitution therapy for adults with blood Phe >600 μmol/L in the US. Recently, the European Commission also approved pegvaliase for treatment of PKU patients aged 16 years or older with blood Phe >600 μmol/L. The analyses presented below were conducted to provide comparative evidence on long-term treatment effectiveness of pegvaliase versus standard of care in adults with PKU.Adult patients (≥18 years) with baseline blood Phe >600 μmol/L who had enrolled in the pegvaliase phase 2 and phase 3 clinical trials were propensity score-matched to historical cohorts of patients treated with “sapropterin + diet” or with “diet alone”. These cohorts were derived from the PKU Demographics, Outcome and Safety (PKUDOS) registry and compared for clinical outcomes including blood Phe concentration and natural intact protein intake after 1 and 2 years. Propensity scores were estimated using logistic regression with probability of treatment as outcome (i.e. pegvaliase, “sapropterin + diet”, or “diet alone”) and patient demographic and disease severity covariates as predictors. An additional analysis in adult PKU patients with baseline blood Phe ≤600 μmol/L comparing non-matched patient groups “sapropterin + diet” to “diet alone” using PKUDOS registry data only was also conducted.The analyses in patients with baseline blood Phe >600 μmol comparing pegvaliase with “sapropterin + diet” (N = 64 matched pairs) showed lower mean blood Phe concentrations after 1 and 2 years with pegvaliase (505 and 427 μmol/L) versus “sapropterin + diet” (807 and 891 μmol/L); mean natural intact protein intake after 1 and 2 years was 49 and 57 g/day respectively with pegvaliase versus 23 and 28 g/day with “sapropterin + diet”. The analysis comparing pegvaliase with “diet alone” (N = 120 matched pairs) showed lower mean blood Phe at 1 and 2 years with pegvaliase (473 and 302 μmol/L) versus “diet alone” (1022 and 965 μmol/L); mean natural intact protein intake after 1 and 2 years was 47 and 57 g/day with pegvaliase and 27 and 22 g/day with “diet alone”. Considerably more patients achieved blood Phe ≤600, ≤360, and ≤120 μmol/L and reductions from baseline of ≥20%, ≥30%, and ≥50% in blood Phe after 1 and 2 years of pegvaliase versus standard treatments. The analysis in patients with baseline blood Phe ≤600 μmol/L showed lower blood Phe after 1 and 2 years with “sapropterin + diet” (240 and 324 μmol/L) versus “diet alone” (580 and 549 μmol/L) and greater percentages of patients achieving blood Phe targets ≤600, ≤360, and ≤120 μmol/L and reductions from baseline of ≥20%, ≥30%, and ≥50% in blood Phe.These results support pegvaliase as the more effective treatment option to lower Phe levels in adults with PKU who have difficulty keeping blood Phe ≤600 μmol/L with “diet alone”. For patients with blood Phe ≤600 μmol/L, adding sapropterin to dietary management is an appropriate treatment option, for those responsive to the treatment.

1H-NMR Metabolomics Identifies Significant Changes in Metabolism over Time in a Porcine Model of Severe Burn and Smoke Inhalation.

Burn injury initiates a hypermetabolic response leading to muscle catabolism and organ dysfunction but has not been well-characterized by high-throughput metabolomics. We examined changes in metabolism over the first 72 h post-burn using proton nuclear magnetic resonance (1H-NMR) spectroscopy and serum from a porcine model of severe burn injury. We sought to quantify the changes in metabolism that occur over time in response to severe burn and smoke inhalation in this preliminary study. Fifteen pigs received 40% total body surface area (TBSA) burns with additional pine bark smoke inhalation. Arterial blood was drawn at baseline (pre-burn) and every 24 h until 72 h post-injury or death. The aqueous portion of each serum sample was analyzed using 1H-NMR spectroscopy and metabolite concentrations were used for principal component analysis (PCA). Thirty-eight metabolites were quantified in 39 samples. Of these, 31 showed significant concentration changes over time (p < 0.05). PCA revealed clustering of samples by time point on a 2D scores plot. The first 48 h post-burn were characterized by high concentrations of histamine, alanine, phenylalanine, and tyrosine. Later timepoints were characterized by rising concentrations of 2-hydroxybutyrate, 3-hydroxybutyrate, acetoacetate, and isovalerate. No significant differences in metabolism related to mortality were observed. Our work highlights the accumulation of organic acids resulting from fatty acid catabolism and oxidative stress. Further studies will be required to relate accumulation of the four organic carboxylates identified in this analysis to outcomes from burn injury.

Serum amino acid profiles and risk of type 2 diabetes among Japanese adults in the Hitachi Health Study

Amino acids have emerged as novel biomarkers for predicting type 2 diabetes (T2D), but the epidemiologic data linking circulating amino acid profiles with T2D are sparse in Asian populations. We conducted a nested case-control study within a cohort of 4,754 nondiabetic Japanese employees who attended a comprehensive health checkup in 2008–2009 and agreed to provide blood samples. During a 5-year follow-up, incident T2D cases were ascertained based on plasma glucose, glycated hemoglobin, and self-report. Two controls matched to each case on sex, age, and the date of serum sampling were randomly selected by using density sampling, resulting in 284 cases and 560 controls with amino acid measures. High concentrations of valine, leucine, isoleucine, phenylalanine, tyrosine, alanine, glutamate, ornithine, and lysine were associated with an increased risk of incident T2D, in a linear manner. High glutamine concentrations were associated with a decreased risk of incident T2D. Further adjustment for the homeostasis model assessment of insulin resistance attenuated these associations. Overall, these amino acids may be novel useful biomarkers in the identification of people at risk of T2D before overt symptoms. Insulin resistance may account for or mediate the relationship between these amino acids and risk of incident T2D.

Assessment of eleven South African peach cultivars for susceptibility to brown rot and blue mould

Species of Penicillium (blue mould) and Monilinia (brown rot) are major causes of postharvest loss of stone fruit. Breeding for resistance to these pathogens is a sustainable option that could reduce over reliance on postharvest chemical interventions to control the diseases. This study was aimed at selecting peach cultivars that are resistant to blue mould and brown rot pathogens through in vivo assays against the causative agents. Red and yellow skinned peach cultivars were artificially infected with Monilinia laxa and Penicillium expansum whilst the same cultivars were also assessed as naturally infected fruit. Fruit were stored at 0 °C for 14 and 21 days, and thereafter kept at 15 °C for 3 days to simulate market shelf condition. Physicochemical traits, such as fruit pH, antioxidant activity, total anthocyanins, and total phenols were measured at harvest, and after 14 days and 21 days of storage. The blue mould pathogen was more virulent than the brown rot pathogen in the fruit. The red cultivars showed less brown rot incidence (20%–35%) compared to the yellow cultivars (35%–65%). Artificial infections stimulated a higher biochemical activity in the fruit compared to natural infections. In general peach cultivars with high contents of antioxidant compounds had lower pathogen incidence. ‘Temptation’, (a red cultivar) showed highest resistance compared to the other peach cultivars used in this experiment and this was correlated to the high phenylalanine lyase activity, phenolic compounds, and concentrations of chlorogenic, caffeic acid and anthocyanin exhibited by the cultivar. Breeders can use these tests as indicative for blue and brown mould resistance.