Relevant bibliographies by topics / Phenylalanine Phenylketonuria

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Academic literature on the topic 'Phenylalanine Phenylketonuria'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Phenylalanine Phenylketonuria"

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Halil, Kazanasmaz, and Karaca Meryem. "Plasma amino acid levels in a cohort of patients in Turkey with classical phenylketonuria." Asian Biomedicine 14, no. 2 (August 4, 2020): 59–65. http://dx.doi.org/10.1515/abm-2020-0009.

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AbstractBackgroundIn patients with phenylketonuria, the central nervous system is adversely affected by noncompliance with diet. The levels of phenylalanine and many different amino acids (AAs) in the plasma of patients with phenylketonuria can be measured simultaneously.ObjectivesTo measure the blood plasma levels of neurotransmitter AAs in a cohort of patients in Sanliurfa province, Turkey, with phenylketonuria for use as a support parameter for the follow-up of patients.MethodsThe phenylketonurics that we followed (n = 100) were divided into 2 groups according to their compliance with their dietary treatment. Plasma AA analysis results of phenylketonurics were compared with those of healthy children in a control group (n = 50).ResultsIn the diet incompliant group (n = 56), the mean levels of γ-aminobutyric acid (GABA; 0.96 ± 1.07 μmol/L) and glycine (305.1 ± 105.19 μmol/L) were significantly higher than those in the diet compliant group (n = 44; GABA P = 0.005, glycine P < 0.001) and in the control group (GABA and glycine P < 0.001), whereas the mean levels of glutamic acid (39.01 ± 22.94 μmol/L) and asparagine (39.3 ± 16.89 μmol/L) were lower (P < 0.001) in the diet incompliant group. A positive correlation was observed between the levels of phenylalanine and GABA and glycine. A negative relationship was found between the levels of phenylalanine and glutamic acid and asparagine.ConclusionsA relationship exists between the levels of plasma phenylalanine in a cohort of phenylketonurics in Sanliurfa province, Turkey, and the levels of some excitatory and inhibitory AAs. Excitatory and inhibitory AA levels in plasma may be used as support parameters in the follow-up of patients with phenylketonuria.
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Barclay, A., and O. Walton. "Phenylketonuria: Implications of Initial Serum Phenylalanine Levels on Cognitive Development." Psychological Reports 63, no. 1 (August 1988): 135–42. http://dx.doi.org/10.2466/pr0.1988.63.1.135.

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This study investigated influences of diagnostic phenylalanines, age at initiation of diet, and dietary control, separately and in combination, on cognitive development for 29 phenylketonuric children (17 boys and 12 girls) who ranged in age from 1 to 1,184 days. Initial serum phenylalanine concentrations and age at initiation of therapy were significantly related to cognitive development, whereas neither dietary and biochemical control relative to blood levels of phenylalanine or for these variables in combination exerted a statistically significant effect on measures of functioning. The interaction between initial serum phenylalanine level and age at onset of diet did reach nearly significant proportions, suggesting that the relation between diagnostic phenylalanines and subsequent cognitive development in the phenylketonuric population warrants further study. Despite an approximately 13-point decrease in IQs between initial (1 yr.) and most recent measurements (3 yr.), all 29 children were functioning in the normal or near-normal intellectual range at the most recent testing.
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Clemens, Peter C., Martin H. Schünemann, Alfred Kohlschütter, and Georg F. Hoffman. "Phenylalanine metabolites in phenylketonuria." Journal of Pediatrics 116, no. 4 (April 1990): 665. http://dx.doi.org/10.1016/s0022-3476(05)81624-5.

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Murphy, Glynis H., Sally M. Johnson, Allayne Amos, Eleanor Weetch, Rosemary Hoskin, Brian Fitzgerald, Maggie Lilburn, Lesley Robertson, and Philip Lee. "Adults with untreated phenylketonuria: out of sight, out of mind." British Journal of Psychiatry 193, no. 6 (December 2008): 501–2. http://dx.doi.org/10.1192/bjp.bp.107.045021.

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SummarySome people with phenylketonuria who were born before screening began were never treated and are still alive. Here we report that far fewer people with untreated phenylketonuria were detected than are thought to exist (about 2000). The majority of those traced had high support needs, challenging behaviour and other symptoms of phenylketonuria. No significant differences were found between those who had or had not tried the phenylalanine-restricted diet. A randomised controlled trial is required to examine the effect of trying the low-phenylalanine diet for people with untreated phenylketonuria.
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Konstantinidis, Georgios, Dobrila Radovanov, and Nada Konstantinidis. "Financial justification of investments into special diet for patients with phenylketonuria." Medical review 63, no. 11-12 (2010): 771–74. http://dx.doi.org/10.2298/mpns1012771k.

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Introduction. Phenylketonuria is a genetic disorder of metabolism of amino acid phenylalanine, which results in the absence of phenylalanine hydroxylase, an enzyme that catalyzes the conversion of phenylalanine into tyrosine. It is an autosomal recessive disorder. Screening for phenylketonuria in Voivodina started in 2003. Screening data are shown in this paper. Treatment of phenylketonuria is based on a strict, life long, low protein diet with the controlled phenylalanine intake. Diet must start early, in the first weeks of life. The aim of the diet is to reduce natural protein intake and to cover protein needs by special phenylalanine free protein products. There is a big variety of formulas found available on the market for treatment of phenylketonuria. All of them are free of phenylalanine and very expensive. Discussion. Till May 2005 there was no refunding for these products in our country. According to the decision made by the Provincial Secretariat for Health, providing all children with protein supplement in their first year of life started at the Institute for Child and Youth Healthcare. In September 2007 the Republic Fund for Health Insurance started to refund protein supplement and low protein products for all children up to the age of 18 years. Conclusion. Besides all technical and organizational difficulties associated with this work, this paper also shows how, by good prevention of phenylketonuria complications, much more money can be saved than it has been invested, even in countries with low amounts of money allocated for this purpose (in absolute figures).
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Ben Abdelaziz, Rim, Nizar Tangour, Amel Ben Chehida, Sameh Haj Taieb, Moncef Feki, Hatem Azzouz, and Neji Tebib. "Morning specimen is not representative of metabolic control in Tunisian children with phenylketonuria: a repeated cross-sectional study." Journal of Pediatric Endocrinology and Metabolism 33, no. 8 (August 27, 2020): 1057–64. http://dx.doi.org/10.1515/jpem-2020-0025.

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AbstractObjective and methodsTo 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.ResultsThere 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 24 h 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 8–20 h. Percentages of high phenylalanine concentrations over the last semester were higher in patients with poor metabolic control over the 24 h (21% ± 43 vs. 0% ± 9%); p=0.043.ConclusionA 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.
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VILLEGAS CAMPOS, ELEN, Geanlucas Mendes Monteiro, Elenir Rose Jardim Cury Pontes, and Liane de Rosso Giuliani. "CHARACTERIZATION OF PATIENTS DIAGNOSED WITH PHENYLKETONURIA IN THE NEONATAL TREATMENT REFERENCE SERVICE." International Journal for Innovation Education and Research 7, no. 12 (December 31, 2019): 81–89. http://dx.doi.org/10.31686/ijier.vol7.iss12.2013.

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Phenylketonuria is an inborn error of autosomal recessive genetic metabolism, with partial or total deficiency of the hepatic enzyme phenylalanine hydroxylase, which converts L-phenylalanine into tyrosine, causing accumulation of phenylalanine at brain and serum levels, interfering with brain protein synthesis causing several damages. This study aimed to characterize patients diagnosed with phenylketonuria at the Neonatal Screening Reference Service from 2008 to 2017. Cross-sectional analytical study with a quantitative approach with retrospective data collection from medical records and databases. Data were grouped as baby gender, date of birth, time of birth and neonatal screening examination collection, type of delivery, gestational age and prenatal status, place of origin, phenylketonuria classification and coverage rate of neonatal screening. The sample consisted of 14 patients, where 64% were male, all mothers had prenatal care and the percentage of cesarean delivery prevailed with 57.2%. Of these 85.7% reside in other states of the country and on the classification of the type of phenylketonuria 64.3% have mild phenylketonuria, as for the coverage rate there was a drop in the number of collections in the reference service. This research contributed to characterize the patient diagnosed with phenylketonuria, which allows greater knowledge about the disease carriers, as well as favoring the reduction of irreversible sequels, expenses and morbidity.
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Beckhauser, Mayara Thays, Mirella Maccarini Peruchi, Gisele Rozone De Luca, Katia Lin, Sofia Esteves, Laura Vilarinho, and Jaime Lin. "Neuroradiological findings of an adolescent with early treated phenylketonuria: is phenylalanine restriction enough?" Clinics and Practice 1, no. 2 (May 3, 2011): 25. http://dx.doi.org/10.4081/cp.2011.e25.

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Phenylketonuria is caused by mutations in the enzyme phenylalanine hydroxylase gene, that can result in abnormal concentrations of phenylalanine on blood, resulting in metabolites that can cause brain damage. The treatment is based on dietary restriction of phenylalanine, and noncompliance with treatment may result in damage of the brain function. Brain abnormalities can be seen on magnetic resonance imaging of these individuals. Studies indicate that the appearance of abnormalities in white matter reflects high levels of phenylalanine on the blood. This case will show the clinical and neuroradiological aspects of a teenager with constant control of phenylalanine levels. Despite the continuous monitoring and early treatment, the magnetic resonance imaging identified impressive abnormalities in the white matter. This leads us to one question: is the restriction of phenylalanine sufficient to prevent changes in the white matter in patients with phenylketonuria?
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Ruiz-Vázquez, P., Y. Bel, A. M. Garcia, M. L. Cabello, J. Dalmau, T. Alós, J. L. Catalá, and J. Ferré. "Measurement of Neopterin and Biopterin in Urine from Phenylketonuria Heterozygotes and Normal Controls." Pteridines 3, no. 3 (September 1991): 177–80. http://dx.doi.org/10.1515/pteridines.1991.3.3.177.

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The effect of an oral load of phenylalanine (100 mg/kg body weight) on the levels of neopterin and biopterin in urine has been determined in 8 heterozygotes for classical phenylketonuria and 25 supposed normal controls. In basal conditions, neopterin and biopterin levels were significantly different between males and females. A significant increase in urinary biopterin was found two hours after the phenylalanine load, both in heterozygotes and in normal homozygotes. This increase was maintained at least until the fourth hour. Neopterin levels did not suffer any change during that period. Comparison of urinary pteridines from normal controls and phenylketonuria carriers showed that there were no significant differences between both groups neither before nor after the phenylalanine load. From these data we concluded that measurement of biopterin and neopterin in urine cannot help in the identification of heterozygotes for phenylketonuria.
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Shahid, Samran. "Phylogenetic Analysis of Phenylalanine Hydroxylase Enzyme and Its Future Aspect in Treatment of Phenylalanine Hydroxylase Enzyme Deficiency (Phenylketonuria)." International Journal of Innovative Science and Research Technology 5, no. 7 (July 29, 2020): 569–72. http://dx.doi.org/10.38124/ijisrt20jul519.

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PAH enzyme is one of the most vital enzymes in protein metabolism of the body. The enzyme has been found in various organisms and thus proves it has evolved along with speciation.PAH catalyses hydroxylation of the aromatic side of the phenylalanine to generate Tyrosine (4-hydroxyphenylalanine), one of the 20 standard amino acids that exist. The buildup of excess phenylalanine in the body due to deficiency of PAH causes a condition called Phenylketonuria which causes significant nerve damage. The condition Phenylketonuria is caused due to genetic mutation in PAH gene (Cr.12 )in an individual which can cause PAH enzyme deficiency. The purpose of this analysis was to use the existing Bioinformatics databases to draw relevant similarities of PAH of Homo sapiens and other organism using BLAST , MSA(Multiple Sequence Alignment) and phylogenetic relation while proposing the use of gene therapy using the data derived to cure Phenylketonuria
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Dissertations / Theses on the topic "Phenylalanine Phenylketonuria"

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Safos, Sarah K. "Phenylketonuria : enzyme replacement therapy using microencapsulated phenylalanine ammonia-lyase." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23754.

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The presence of an extensive enterorecirculation of amino acids between the intestine and the body, allows for the removal of elevated systemic phenylalanine present in the phenylketonuric condition, by oral administration of microencapsulated phenylalanine ammonia-lyase(28). The work presented in this thesis, had the main goal of assessing the feasibility of phenylalanine ammonia-lyase (PAL) loaded collodion microcapsules, in reducing elevated plasma phenylalanine concentrations to standard levels in genetically mutated, ENU2 PKU mice, within a 30 day time frame. The distinguishing aspect from similar previous studies, originated with the available animal model. Rather than artificial induction of elevated phenylalanine plasma levels, the mice representing the human phenylketonuric condition, were mutated strains, deficient in the enzyme phenylalanine hydroxylase.
The first in vivo study established a method for orally feeding microcapsules, over 30 consecutive days, by mixing with soft, unripened cheese. The second animal study confirmed the finding in the first study that there is no significant decrease in the plasma phenylalanine levels within the first seven days of treatment. (Abstract shortened by UMI.)
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Griffiths, Peter V. "Treatment factors and neuropsychological outcome in phenylketonuria." Thesis, University of Stirling, 1997. http://hdl.handle.net/1893/22863.

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Phenylketonuria (PKU) is an inherited metabolic disease that affects about one in 10,000 of the population worldwide. In the classical form of the condition, the hepatic enzyme phenylalanine hydroxlase is absent or much reduced. If untreated, severe or profound mental handicap customarily results due to the accumulation of dietary phenylalanine (phe) which is neurotoxic. The mechanism by which phe impairs growth in the immature nervous system is little understood, but myelin metabolism appears to be disturbed. Treatment is by reduction of phe in daily food intake. Treatment should ideally begin in the neonatal period if intellectual loss is to be avoided. However, the safe range of phe concentrations during treatment and the age at which treatment can be discontinued without further damage being inflicted are uncertain. The studies reported in this volume investigated neuropsychological outcomes of treatment control and cessation factors. In addition, the question of whether executive functions are especially vulnerable to elevated phe concentrations during treatment was addressed. Patient samples conformed to the practice adopted in the West of Scotland regional centre for the management of PKU of maintaining dietary treatment until age 10 or beyond. Almost exclusively, negative findings emerged. These suggested that, if control of phe intake conforms to current UK recommendations for the preschool and primary years, neither global nor specific intellectual deficit result. Furthermore, the data supported the view that cessation of treatment at 10 years of age does not have harmful consequences. These findings have direct implications for the formulation of clinical policy on the treatment of PKU, but it must be recognized that the history of the successful treatment of PKU and mass screening for the disease spans a mere three decades. Thus, treatment outcome research to date is based only on children and young adults. In future investigations, a life-span approach will be required before the issues raised in this thesis can be finally settled.
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Rees, D. "Characterisation of the rat phenylalanine hydroxylase gene promotor." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343614.

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Chung, Sangbun. "The effect of maternal blood phenylalanine level on mouse maternal phenylketonuria offspring." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/289025.

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Maternal phenylketonuria is a disease process caused by the adverse effects of high maternal blood phenylalanine (PHE) on the fetus. Unless treated, maternal PKU results in teratogenic effects on the fetus that can lead to mental retardation, microcephaly, intrauterine growth retardation, congenital cardiovascular defects, low birth weight, spontaneous abortion and fetal death. Although PKU has been recognized as a major challenge for many years, surprisingly little is known about the pathophysiologic mechanism(s) of PHE toward the fetus. To more thoroughly investigate the pathogenesis of this heritable disease and to explore potential therapeutic actions, the genetic mouse model Pahenu2 was used. The overall goals of this project were to use the Pah enu2 mouse to examine the effect of maternal blood PHE level on: (1) The pregnancy outcome of maternal PKU offspring as measured by the incidence of spontaneous abortion and certain key measures of development at birth (i.e., head circumference, weight, and crown-rump length of offspring); and (2) The fetal nutritional status of maternal PKU offspring as assessed by the levels of PHE, tyrosine (TYR), and other essential amino acids (EAA) at birth. In this study, we clearly observed that elevated maternal blood PHE levels, whether they were caused by the maternal diet or maternal genotype, were responsible for the fetal abnormalities in maternal PKU. With regard to fetal developmental outcomes, significant reductions in birth weight, crown-rump length, and head circumference were seen in offspring gestated under high maternal blood PHE conditions. The incidence of fetal loss was significantly different between treatment and control groups. Reductions in the levels of alanine, glutamine, and glutamic acid were observed in fetal blood among offspring born to mutant mothers with high blood PHE levels. None of the branched chain amino acids were reduced in maternal PKU offspring. These findings strongly suggest that there are important maternal genotype and dietary components but no fetal genotype component to this maternal PKU model. Given that these maternal factors also appear to be the most important components of human maternal PKU, this model seems certain to provide a valid animal model to overcome the difficulties of human studies.
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Sarkissian, Christineh N. "Enzyme substitution therapy for hyperphenylalaninemia with phenylalanine ammonia lyase : an alternative to low phenylalanine dietaty treatment : effective in mouse models." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37832.

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Phenylketonuria (PKU) and related forms of non-PKU hyperphenylalaninemias (HPA) result from deficiencies in phenylalanine hydroxylase (PAH), the hepatic enzyme that catalyses the conversion of phenylalanine (phe) to tyrosine (tyr). Patients are characterised by a metabolic phenotype comprising elevated levels of phe and some of its metabolites, notably phenyllactate (PLA), phenylacetate (PAA) and phenylpyruvate (PPA), in both tissue and body fluids. Treatment from birth with low-phe diet largely prevents the severe mental retardation that is its major consequence.
Mechanisms underlying the pathophysiology of PKU are still not fully understood; to this end, the availability of an orthologous animal model is relevant. A number of N-ethyl-N-nitrosourea (ENU) mutagenized mouse strains have become available. I report a new heteorallelic strain, developed by crossing female ENU1 (with mild non-PKU HPA) with a male ENU2/+ carrier of a 'severe' PKU-causing allele. I describe the new hybrid ENU1/2 strain and compare it with control (BTBR/Pas), ENU1, ENU2 and the heterozygous counterparts. The ENU1, ENU1/2 and ENU2 strains display mild, moderate and severe phenotypes, respectively, relative to the control and heterozygous counterparts.
I describe a novel method using negative ion chemical ionization gas chromatography/mass spectrometry (NICI-GC/MS) to measure the concentration of PLA, PAA and PPA in the brain of normal and mutant mice. Although elevated moderately in HPA and more so in PKU mice, concentrations of these metabolites are not sufficient to explain impaired brain function; however phe is present in brain at levels associated with harm.
Finally, I describe a new modality for treatment of HPA, compatible with better human compliance: it involves enzyme substitution with non-absorbable and protected phenylalanine ammonia lyase (PAL) in the intestinal lumen, to convert L-phenylalanine to the harmless metabolites (trans-cinnamic acid and trace ammonia). PAL, taken orally, substitutes for the deficient PAH enzyme and depletes body pools of excess phe. I describe an efficient recombinant approach to produce PAL enzyme. I also provide proofs of both pharmacologic and physiologic principles by testing PAL in the orthologous mutant mouse strains with HPA. The findings encourage further development of PAL for oral use as an ancillary treatment of human PKU.
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Viau, Krista S. "Correlation of Age-Specific Phenylalanine Levels on Intellectual Outcome in Patients with Phenylketonuria." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/739.

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It is widely appreciated by the medical community that subtle deficits in intellect, academic skills and executive functioning exist in early treated phenylketonuria (PKU). In this study, we described the relationship between intellectual outcome and concentration/variation in blood phenylalanine (Phe) during specific developmental periods (0-5 years, 6-10 years, >10 years). We also examined the association between mean number of blood Phe samples and maintenance of Phe within treatment range (120-360 ìmol/L) and within one standard deviation (SD) of index of dietary control, defined as the mean of 12-month median Phe. Retrospective data was collected from 55 patients receiving treatment at the University of Utah Metabolic Clinic. Index of dietary control (IDC) and SD blood Phe steadily increased and mean number of samples decreased during each developmental period. The correlation between IDC during 6-10 years of life and perceptual reasoning was -.370 (p = 0.006). Using multivariate linear regression, IDC during 0-5 years and 6-10 years were associated with a 0.5-point decrease and 0.3-point decrease in perceptual reasoning scores for every 100 ìmol/L increase in blood Phe, though associations were nonsignificant (p = 0.067; 0.082). SD of Phe was not associated with any measure of intelligence. The likelihood of IDC >360 ìmol/L in those 6-10 years was 32.3% lower for each additional blood Phe sample per year (p = 0.001). The present study suggests frequent blood Phe monitoring during ages 6-10 years may reduce blood Phe and prevent deficits in perceptual reasoning later in life.
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Carter, Kevin C. (Kevin Craig). "Population genetic variation at the human phenylalanine hydroxylase locus." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23991.

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Denaturing gradient gel electrophoresis (DGGE) and sequencing of the PAH locus has found 38 different mutations on 141 chromosomes in the PKU patients resident in Quebec; mutation analysis is now 92.5% complete. Two novel disease producing alleles (K421, R157N) and one silent allele (IVS6 nt-55) were discovered in this project; these mutations remain unique to the Quebec population. Three novel mutation-(haplotype) combinations were also found (S67P (H1), G218V (H2), V245A (H7)); they are not at hypermutable sites and are therefore compatible with a single homologous recombination event between two different haplotypes. Whereas mutation types (missense 64%, nonsense 6%, splice 9%, frameshifts 6%, silent 15%), resemble those in world populations, the Quebec allele profile differs from that of any European population, reflecting range expansion, founder effects, genetic drift and assimilation. Furthermore, when analyzed by geographic region a stratification of PAH alleles is apparent, reflecting the different demographic histories of Western and Eastern Quebec and Montreal.
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Lam, Melanie. "Drying of red spring wheat seedlings (Triticum aestivum L.) by various methods and investigation of its phenylalanine ammonialyase stability in an in vitro protein digestion." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/1625.

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Phenylketonuria and hyperphenylalanemia are autosomal recessive inborn errors of phenylalanine metabolism that are caused by mutations in the phenylalanine hydroxylase gene. Due to the stringency of the present dietary therapy, alternative treatments are being studied. Phenylalanine ammonia-lyase (PAL) is one of the potential dietary supplements for these patients. PAL is a well-studied plant enzyme which breaks down phenylalanine into trans-cinnamic acid and ammonia (Camm and Towers, 1973). It is found in the cytoplasm of the plant cells and is naturally encapsulated by plant cell walls which may protect it against the acidic pH environment in the gastrointestinal tract. It presumably degrades ingested Phe that circulates in the intestinal lumen. In this study, red spring wheat seedlings (Triticum aestivum L.) found to contain high PAL activity naturally were investigated as a potential alternative oral therapy. Specifically, the objectives were (1) to evaluate different drying methods on generating concentrated and dried preparation of wheat seedlings containing high levels of PAL activity; (2) to examine the retention of PAL activity over three months of storage under various storage conditions; (3) to determine the stability of PAL activity in simulated human digestion condition to establish if further study of using plant source enzyme in vivo is warranted. Freeze-drying (FD) was found to have retained the most activity (>90 % recovery dry wt basis) compared to air-drying (AD) and vacuum-microwave drying (VMD) for both leaf and residual seed/root samples. Pre-freezing of leaf tissues at -18 °C before FD significantly retained the highest PAL activity compared to pre-freezing at -25 °C, -35 °C, and -80 °C (P<0.05). Over three months of storage, 60-80 % of PAL activity was recovered in leaf and —100 % was recovered in residual seed/root tissues after storage at -20 °C. After in vitro protein digestion, 36% and 42 % of PAL activity was recovered in fresh leaf and root tissues respectively; however, FD tissues were found to be susceptible to proteases and acidic environment and no activity was recovered after three hours of in vitro protein digestion. High performance liquid chromatography (HPLC) analysis of the residual Phe after in vitro protein digestion confirmed that fresh tissues had significantly higher conversion of Phe than that of FD tissues. Together, these results suggest that red spring wheat seedlings may have potential as a dietary supplement for phenylketonuric patients while further study to enhance PAL activity in plant preparations is required.
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Turki, Abrar Mohammed. "Application of stable isotope tracers to examine phenylalanine metabolism and protein requirements in children with phenylketonuria (pku)." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53095.

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Phenylketonuria (PKU) is an inherited inborn error of phenylalanine (PHE) metabolism caused by deficiency of hepatic enzyme phenylalanine hydroxylase (PAH). Therefore, PHE accumulates in plasma leading to mental retardation and developmental delay. Kuvan® (Sapropterin dihydrochloride), a synthetic form of tetrahydrobiopterin (BH₄), has been shown to reduce plasma PHE levels in PKU, but not all patients respond to sapropterin treatment. The major mode of treatment remains nutritional management with dietary restriction of PHE and provision of sufficient protein. The dietary protein requirement in children with PKU remains unknown. Therefore the objectives of the current thesis were: 1) to identify sapropterin responsiveness in PKU children using a minimally invasive L-[1-¹³C] phenylalanine breath test (¹³C-PBT), and 2) to determine protein requirements in PKU children using the indicator amino acid oxidation (IAAO) technique. Experiment 1- Nine children with PKU (5-18y) underwent ¹³C-PBT tracer protocols twice, once before and once after 1-2 weeks of sapropterin therapy. ¹³CO₂ was measured using isotope ratio mass spectrometer (IRMS). The study protocol was tested in healthy children (n= 6) as proof of principle. Experiment 2- Four PKU children (5-18y) were recruited to participate in test protein intakes (ranging from deficiency to excess 0.2 – 3.2 g/kg/d) with the IAAO protocol using L-[1-¹³C] leucine, followed by collection of breath and urine samples over 8 hours. Results 1- ¹³CO₂ productions in all children with PKU pre-sapropterin treatment were low, except in one child (PKU04). Five children with PKU showed a significantly higher peak enrichment after sapropterin treatment at 20min. Three PKU children had no change in ¹³CO₂ production post sapropterin therapy. Results 2- The mean protein requirement, identified using 2-phase linear regression analysis was determined to be 1.85 g/kg/d. This result is significantly higher than the most recent PKU recommendations (2014) (1.14 – 1.33g/kg/d, based on 120-140% above current recommended dietary allowance RDA). These findings show that the ¹³C-PBT can be a minimally invasive method to examine in vivo PHE metabolism in PKU children responsive to sapropterin therapy. Also, current recommendations for optimal protein intake may be underestimated.
Land and Food Systems, Faculty of
Graduate
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Nalin, Tatiéle. "Hiperfenilalaninemia por deficiência de fenilalanina hidroxilase : avaliação da responsividade ao BH4 em pacientes acompanhados no Serviço de Genética Médica do HCPA e que apresentam controle metabólico adequado." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/31887.

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Introdução: Estudos recentes, utilizando vários protocolos, têm demonstrado que pacientes com Hiperfenilalaninemia por deficiência de fenilalanina hidroxilase (HPA-PAH) podem apresentar redução das concentrações plasmáticas de fenilalanina (Phe) mediante a administração de tetrahidrobiopterina (BH4). Objetivo: Determinar, em uma amostra de pacientes brasileiros com HPA-PAH, a responsividade à administração de dose única de BH4 por meio de um protocolo incluindo o teste de sobrecarga simples de Phe e o teste combinado de sobrecarga de Phe+BH4. Métodos: Foram incluídos no estudo pacientes com idade ≥ 4 anos, em tratamento dietético e que possuíam mediana de Phe plasmática inferior a 10mg/dL no ano anterior à inclusão. Foram realizados teste de sobrecarga simples de Phe, utilizando 100mg/kg de L-Phe (Teste 1) e teste combinado de Phe+BH4, utilizando 100mg/kg de L-Phe e 20mg/kg de BH4 (Teste 2), com intervalo de uma semana entre ambos. A ingestão do BH4 ocorreu após três horas da ingestão da Phe. Foram realizadas coletas de sangue no ponto basal e após três, 11 e 27h da ingestão de Phe (T0, T1, T2 e T3 dos testes 1 e 2, respectivamente). Para ser considerado responsivo, o paciente deveria apresentar evidência de redução dos níveis de Phe associada à administração do BH4 de acordo com pelo menos um dos seguintes critérios: critério A – análise das diferenças, em percentual, dos valores de Phe nos pontos T1 e T2 dos Testes 1 e 2; critério B – análise das diferenças, em percentual, dos valores de Phe nos pontos T1 e T3 dos Testes 1 e 2 e critério C – análise da diferença, em percentual, das áreas abaixo da curva de Phe entre os Testes 1 e 2. A classificação de responsividade foi também comparada com quatro critérios adicionais: critério D – análise da diferença, em percentual, dos valores de Phe nos pontos T1 e T2 do Teste 2; critério E – análise da diferença, em percentual, dos valores de Phe nos pontos T1 e T3 do Teste 2; cinco pacientes participaram de estudo anterior do grupo e foram também classificados através do critério F – análise da diferença, em percentual, dos valores de Phe após 8h da sobrecarga simples com BH4 e do critério G – análise da diferença, em percentual, dos valores de Phe após 24h da sobrecarga simples com BH4. Para todos os critérios foi utilizado como ponte de corte redução ≥ 30%. Resultados: Dezoito pacientes, com mediana de idade de 12 anos, participaram do estudo. Dez pacientes apresentavam a forma Leve de HPA-PAH e oito a forma Clássica. Seis pacientes foram considerados responsivos de acordo com os critérios adotados (Clássica: 2; Leve: 4). Houve concordância de responsividade entre os critérios A e B em relação ao C (Índice Kappa=0,557; p=0,017). Dos pacientes com genótipo disponível (n=16), seis possuíam dados de responsividade ao BH4 descritos na literatura, que foram concordantes com os encontrados no presente estudo. Conclusão: Dados relativos à responsividade, tipo de HPA-PAH e genotipagem estão de acordo com descrito na literatura. Haja vista a diferença de responsividade dos pacientes ao BH4 conforme o critério de classificação utilizado, salienta-se a importância de uma definição cautelosa de responsividade e que não seja baseada em um único critério. A comparação entre a sobrecarga simples de Phe e combinada de Phe+BH4 parece ser um critério adequado para avaliar responsividade ao BH4 em pacientes com HPA-PAH que apresentam bom controle metabólico quando em tratamento dietético.
Introduction: Recent studies using different protocols showed that patients with hyperphenylalaninemia due to phenylalanine hydroxylase deficiency (HPA-PAH) may have a reduction in phenilalanine (Phe) plasma concentrations after tetrahydrobiopterin (BH4) administration. Objective: To determine responsiveness to the administration of a single dose of BH4, in a sample of Brazilian patients with HPA-PAH using a protocol that includes the simple Phe loading test and the combined Phe+BH4 loading test. Methods: Patients included in the study were ≥ 4 years of age; their median Phe plasma concentration was ≤ 10mg/dL, and all underwent dietary treatment in the 12 months before inclusion in the study. Participants received a simple Phe loading test using 100mg/kg L-Phe (Test 1) and a combined Phe+BH4 loading test using 100mg/kg L-Phe and 20mg/kg /BH4 (Test 2) at a one-week interval. BH4 was ingested three hours after Phe ingestion. Blood samples were collected at baseline and three, 11 and 27h after Phe ingestion (time points T0, T1, T2 and T3 in Tests 1 and 2). To be classified as responsive, there should be evidence that the patient had a reduction in Phe levels associated with BH4 administration according to at least one of the criteria used: criterion A – analysis of percentage differences of the Phe values at time points T1 and T2 for Tests 1 and 2; criterion B – analysis of percentage differences of Phe values at time points T1 and T3 for Tests 1 and 2; and criterion C – analysis of percentage differences of the areas under the Phe curve for Tests 1 and 2. Responsiveness classifications were also compared according to four additional criteria: criterion D – analysis of percentage differences of the Phe values at time points T1 and T2 for Test 2; criterion E – analysis of percentage differences of Phe values at time points T1 and T3 for Test 2; criterion F – analysis of percentage difference of Phe values 8h after simple BH4 loading used for five patients that participated in a previous study conducted by the same authors; and criterion G – analysis of percentage difference of Phe values 24 h after simple BH4 loading, also used for the patients in the same previous study. The cut-off point for all criteria was a reduction of ≥ 30%. Results: Eighteen patients (median age = 12 years) were included in the study. Ten patients had mild HPA-PAH and eight, classical HPA-PAH. Six patients were responsive according to the criteria used (Classical: 2; Mild: 4). Responsiveness was concordant for criteria A and B when compared with criterion C (kappa=0.557; p=0.017). Of the patients whose genotype was available (n=16), six had data about BH4 responsiveness described in the literature, and these data were in agreement with our findings. Conclusion: Data about responsiveness, HPA-PAH type and genotype were in agreement with those described in the literature. The difference in BH4 responsiveness of patients according to classification criterion emphasizes the importance of a careful definition of responsiveness not based on a single criterion. The comparison of simple Phe loading and combined Phe+BH4 loading seems to be an adequate criterion to evaluate responsiveness to BH4 in patients with HPA-PAH and good metabolic control when following a dietary treatment.
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Books on the topic "Phenylalanine Phenylketonuria"

1

Low protein cookery for phenylketonuria. 2nd ed. Madison, Wis: University of Wisconsin Press, 1988.

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Schuett, Virginia E. Low protein cookery for phenylketonuria. 3rd ed. Madison: University of Wisconsin Press, 1997.

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Lorimer, Cathy. Low-protein cuisine. Glendale Heights, IL (128 E. Drummond Ave., Glendale Heights 60139): C.L. Lorimer, 1990.

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Schuett, Virginia E. Apples to zucchini: A collection of favorite low protein recipes. Seattle, WA: National PKU News, 2005.

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Depenveĭller, Marii︠a︡. Bezbelkovai︠a︡ kulinarii︠a︡ dli︠a︡ fenilketonurii. Toronto: AA Biosciences Inc., 2012.

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Schuett, Virginia E. Low protein food list for PKU. Seattle, WA: National PKU News, 1995.

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Evans, Janette M. Fenilalanina (PHE) para tres: Un sistema de control para los equivalentes 1, 2, y 3. Portland, Or: La Divisio n de Nutricio n/Cli nica Metabo lica, Child Development and Rehabilitation Center, Oregon Health Sciences University, 1998.

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Evans, Janette M. PHE for three: A tracking system for 1, 2, and 3 equivalents. 3rd ed. Portland, Or: Nutrition Division/Metabolic Clinic, Child Development and Rehabilitation Center, Oregon Health Sciences University, 1998.

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Vernon, Hilary. Phenylketonuria. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0064.

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Phenylketonuria is an autosomal recessive biochemical disorder most often resulting from a deficiency of phenylalanine hydroxylase, the enzyme which catalyzes the conversion of phenylalanine to tyrosine. The remainder of the cases are caused by abnormalities in the phenylalanine hydroxylase cofactor, tetrahydrobiopterin. Phenylketonuria can be divided into three subgroups based on the elevation of plasma phenylalanine in the untreated state: “classical,” “variant,” and “benign.” Untreated individuals with classical phenylketonuria develop neurocognitive abnormalities including seizures, microcephaly, and severe intellectual disability. Other clinical effects include a musty body odor, eczema, and reduced skin pigmentation. Treatment, which includes dietary restriction of phenylalanine, supplementation with synthetic protein, and, in some cases, administration of a synthetic form of tetrahydrobiopterin, is successful in preventing the long-term consequences of phenylketonuria.
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van Spronsen, Francjan J., and Robin H. Lachmann. Phenylketonuria and Hyperphenylalaninemia. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199972135.003.0012.

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Phenylketonuria (PKU) is the prototype treatable genetic disorder and most advanced countries have been performing newborn screening for more than 40 years. Institution of a low-protein diet early in life can reduce the concentration of phenylalanine in the blood and the brain, and prevent the severe learning and behavioral difficulties that were historically associated with PKU. Interestingly, as the brain matures it becomes resistant to the toxic effects of phenylalanine. The effects of high phenylalanine levels on the adult brain are a subject of active research, but, unlike the effects on IQ seen in the first decade of life, they appear to be reversible. The most important effect of high phenylalanine levels in adults is teratogenicity, and in many ways the maternal PKU syndrome is a more devastating disease than PKU itself. Fortunately, maternal PKU syndrome is preventable if women with PKU maintain strict control of phenylalanine levels throughout pregnancy.
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Book chapters on the topic "Phenylalanine Phenylketonuria"

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Giżewska, Maria. "Phenylketonuria: Phenylalanine Neurotoxicity." In Nutrition Management of Inherited Metabolic Diseases, 89–99. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14621-8_9.

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Loo, Y. H., K. E. Wisniewski, K. R. Hyde, T. R. Fulton, Y. Y. Lin, and H. M. Wisniewski. "The Neurotoxic Metabolite of Phenylalanine in Phenylketonuria." In Dietary Phenylalanine and Brain Function, 249–53. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_30.

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Koch, R., E. G. Friedman, C. Azen, F. dela Cruz, H. Levy, R. Matalon, B. Rouse, and W. B. Hanley. "Maternal Phenylketonuria Collaborative Study (MPKUCS): USA and Canada." In Dietary Phenylalanine and Brain Function, 269–71. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_34.

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Güttler, Flemming. "Epidemiology and Natural History of Phenylketonuria and Other Hyperphenylalaninemias." In Dietary Phenylalanine and Brain Function, 213–27. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_26.

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Ledley, Fred D., and Savio L. C. Woo. "Reconsidering the Genetics of Phenylketonuria: Evidence from Molecular Genetics." In Dietary Phenylalanine and Brain Function, 228–37. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_27.

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Matalon, Reuben, Kimberlee Michals, Debra Sullivan, Louise Wideroff, and Paul Levy. "Aspartame Consumption in Normal Individuals and Carriers for Phenylketonuria." In Dietary Phenylalanine and Brain Function, 41–52. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_4.

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Nielsen, Jytte Bieber. "Effect of Dietary Tryptophan Supplement on Neurotransmitter Metabolism in Phenylketonuria." In Dietary Phenylalanine and Brain Function, 261–64. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_32.

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Lou, Hans C. "Increased Vigilance and Dopamine Synthesis Effected by Large Doses of Tyrosine in Phenylketonuria." In Dietary Phenylalanine and Brain Function, 254–60. Boston, MA: Birkhäuser Boston, 1988. http://dx.doi.org/10.1007/978-1-4615-9821-3_31.

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Kirby, M. L., and S. T. Miyagawa. "The Effects of High Phenylalanine Concentration on Chick Embryonic Development." In Carbohydrate and Glycoprotein Metabolism; Maternal Phenylketonuria, 634–40. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2175-7_22.

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Michals, K., M. Lopus, P. Gashkoff, and R. Matalon. "Phenylalanine Metabolites in Treated Phenylketonuric Children." In Practical Developments in Inherited Metabolic Disease: DNA Analysis, Phenylketonuria and Screening for Congenital Adrenal Hyperplasia, 212–14. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4131-1_27.

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Conference papers on the topic "Phenylalanine Phenylketonuria"

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Zhuo Wang, Ya-zhu Chen, Su Zhang, and Zhen Zhou. "Investigation of a Phenylalanine-Biosensor System for Phenylketonuria Detection." In 2005 IEEE Engineering in Medicine and Biology 27th Annual Conference. IEEE, 2005. http://dx.doi.org/10.1109/iembs.2005.1616825.

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