Blood Tyrosine Research Articles

Tyrosinemia associated with perinatal infection with cytomegalovirus

A premature infant presented with elevated concentrations of tyrosine in blood and urine, evidence of hepatocellular damage, demineralization of the bones, and a renal Fanconi syndrome. This is the clinical picture found in hereditary tyrosinemia. The infant also had a perinatal infection with cytomegalovirus.

Effects of oral phenylalanine load on plasma glucagon, insulin, amino acid and glucose concentrations in man.

An oral phenylalanine load provokes a significant drop in serum tyrosine levels in children with phenylketonuria [8]. The aim of the present investigation was to examine the response of insulin and glucagon to oral phenylalanine loading as these hormones are known to have a hypoaminoacidaemic effect. Six adult normal weight and healthy men were loaded orally with 0.6 mmol L-phenylalanine per kg body weight after an overnight fast. Serum phenylalanine increased within 10 min after the load and reached a maximum concentration at 30 min. Serum tyrosine increased within 10 min after the load and reached a maximum concentration at 2 h. Plasma glucagon and insulin increased during the first 10 min after the load and reached a peak twice the fasting levels at 30 min after the load. The molar insulin/glucagon ratio remained unchanged during the first 20 min after the load but then declined by 50% at 2 h. Associated with this decline plasma amino acid concentration (except phenylalanine and tyrosine) declined by approximately 15%. The decline was most marked for isoleucine, leucine, methionine and valine. As the hypoaminoacidaemic effect of insulin and glucagon is known to be most marked for these four amino acids plus phenylalanine and tyrosine, the response of insulin and glucagon to a phenylalanine load may influence not only the fate of phenylalanine given but also the blood tyrosine level.

Effect of Dietary Threonine Supplementation on Tyrosine Toxicity in the Rat

The objective of this study was to determine the effect of threonine supplementation on tyrosine metabolism in rats fed a low protein diet with excess tyrosine. The growth retardation and the development of eye and paw lesions that occur in rats ingesting a basal plus 3% or 5% L-tyrosine diet could be alleviated partially by the addition of 0.5% or 1.0% L-threonine to the diet. An increased blood tyrosine level in rats fed excess tyrosine was also lowered by threonine supplementation. In tyrotoxic conditions, the activities of liver tyrosine transaminase (EC 2.6.1.5) and threonine dehydratase (EC 4.2.9.16) were elevated, but p-hydroxyphenyl pyruvic acid oxidase (EC 1.13.11.27) which is also intimately associated with tyrosine toxicity was found to be inactivated. Furthermore, biosynthesis of ascorbic acid in liver was significantly lowered in this condition. However, addition of L-threonine in the diet, not only could cure the signs developed due to excess tyrosine, but also could affect the levels of enzymes studied.

Tyrosine-Induced Eye and Skin Lesions

Tyrosine-induced eye and skin lesions in man are an autosomal, recessive, inherited syndrome associated with tyrosinemia, tyrosinuria, and increased urinary excretion of tyrosine metabolites. Patients have mild to severe keratitis and erosive and hyperkeratotic lesions on the palms and soles. The degree of involvement was variable in the small number of patients studied. Mental retardation is frequently a part of the syndrome. A low-tyrosine low-phenylalanine diet lowers blood tyrosine level and leads to healing of the skin and eye lesions. Early dietary treatment may prevent mental retardation.

Biochemical post-mortem findings in depressed patients

Biochemical human post-mortem studies on depressed patients indicate an unspecific deficiency of neurotransmitters in several brain areas. The loss of drive of these patients could be correlated with a decrease of striatal dopamine concentration. Noradrenaline was significantly diminished in red nucleus, a fact which points to the characteristic posture of depressed patients. Serotonin was diminished in all brain areas. During remission all values trended to be normal. There also exists a circadian disrhythm in depressed patients resulting in lowered VMA- and HVA-levels in urines during the morning and a remission to normal values in the evening. This agrees with the findings of lowered blood tyrosine levels in the morning. The ratio of blood tyrosine and tryptophan is disturbed during depression and recovers during remission. Central and peripheral biochemical mechanisms seems to be involved in depression syndrom.

Studies on the experimental phenylketonuria in rats.

Wister albino pregnant rats were fed on pellets containing 3.5% L-phenylalanine (Phe) from 10 days before the expected date of birth. The diet was then switched to 7% Phe pellets at the third week after birth. Baby rats were reared with breast milk, and weaned at the end of the 4th week after birth; thereafter, they were reared with a normal diet for one week at the 5th week, and then were given 7% Phe diet from the 6th week. These rats, which were reared with a diet of high Phe, showed a similar metabolic pattern to that of human phenylketonuria (PKU) in the following aspects: definite suppression of the liver Phe hydroxylase activity, excretion of a large amount of phenylpyruvic acid (PPA) and phenyllactic acid (PLA) into urine, and an elvated level of blood Phe content. But, they had an excessive amount of blood tyrosine (Tyr), and concurrently excreted massive homogentisic acid (HGA) in urine just as in human tyrosinemia alkaptonuria. The absence of urinary o-hydroxyphenylacetic acid (o-HPAA) was also a distinct difference from human PKU. In some rats, mild inhibition of the liver Phe hydroxylase activity was observed. In other rats, there was no excretion of PPA into urine as in human hyperphenylalaninemia. Further, the regulatory mechanism of Phe catabolism of experimental PKU was discussed by analysing the enzyme activity of the liver Phe hydroxylase, phenylalanine-pyruvate (Phe-Pyr) transaminase and tyrosine alpha-ketoglutarate (Tyr-alpha-Kg) transaminase at different developmental stages of the rats.

A modified automated fluorometric method for tyrosine determination in blood spotted on paper: A mass screening procedure for tyrosinemia

A modified version of the Hochella [2] automated fluorometric technique for tyrosine determination is presented as a mass screening procedure for tyrosinemia. With this technique, 85 000 tests a year can be done with one Auto-Analyzer. In the province of Quebec, 17 cases of hereditary tyrosinemia have been detected with this method over the past three years (208 000 tests). Although the number of false positives is high, blood tyrosine determination remains, to our knowledge, the only mass screening procedure available to detect hereditary tyrosinemia.

Hypertension, antihypertensive drugs and norepinephrine in blood vessels

Publisher Summary This chapter discusses the hypertension, antihypertensive drugs, and norepinephrine in blood vessels. The activity of tyrosine hydroxylase in the mesenteric artery was markedly reduced in the spontaneously hypertensive rat (SHR) compared to normotensive “Wistar” rats. A backcrossed SHR is utilized with an intermediate degree of hypertension which was obtained by mating the SHR with normotensive “Wistar” rats. These rats had an intermediate fall in tyrosine hydroxylase activity in the mesenteric artery. There thus appeared to be an inverse relationship between blood pressure and tyrosine hydroxylase activity. Aromatic l -amino acid decarbocylase activity may also be decreased in the vasculature of the SHR. The activity of synthetic catecholamine enzymes in the mesenteric artery tend to decrease, whereas the activity of the degradative enzymes appears to increase. Both the enzymes of synthesis and degradation may be altered simultaneously to regulate neurotransmitter activity. The enzymatic adaptations noted in the aorta, and mesenteric arteries of hypertensive rats need not necessarily mean that identical enzymatic alterations occur in veins, or in all arterial beds.

Hereditary tyrosinemia in the province of Quebec: prevalence at birth and geographic distribution.

Hereditary tyrosinemia is a severe metabolic disorder of the newborn for which a very low prevalence at birth has been reported throughout the world. During a 2‐year period, the Quebec Network of Genetic Medicine has tested blood tyrosine in 81.6 % of newborns. Twelve babies with hereditary tyrosinemia were detected by biochemical screening and two more cases were identified by pediatricians. Prevalence at birth way 0.8 case per 10,000 live births in the province of Quebec as a whole; the Chicoutimi‐Lac St. Jean region was found to have an exceptional concentration of 14.6 caqes per 10,000 live births and a frequency of carriers of 1 in 14 persons. such an experimental screening program helps define health problems in a population.

Hormonal influences on the concentration of tyrosine in blood

Serum tyrosine is not a good indicator of thyroid function. Levels are lower in men than in women and still lower in pregnancy. Administration of glucose lowers serum tyrosine both in the presence and absence of insulin. Insulin-induced hypoglycemia has the same effect. In active acromegaly serum tyrosine is normal. Mesterolone, Lyndiol 2.5®, glucagon and epinephrine lower serum tyrosine concentration.

Hyperaminoacidemia effects on intestinal transport of related amino acids.

ARTICLESHyperaminoacidemia effects on intestinal transport of related amino acidsRA Wapnir, RL Hawkins, and F LifshitzRA Wapnir, RL Hawkins, and F LifshitzPublished Online:01 Oct 1972https://doi.org/10.1152/ajplegacy.1972.223.4.788MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByProfiling of faecal water and urine metabolites among Papua New Guinea highlanders believed to be adapted to low protein intake31 July 2017 | Metabolomics, Vol. 13, No. 9Tyrosine supplementation in phenylketonuria: Diurnal blood tyrosine levels and presumptive brain influx of tyrosine and other large neutral amino acidsThe Journal of Pediatrics, Vol. 139, No. 3Response in hepatic removal of amino acids by the sheep to short-term infusions of varied amounts of an amino acid mixture into the mesenteric vein9 March 2007 | British Journal of Nutrition, Vol. 85, No. 6Regulation of l-methionine and l-lysine uptake in chicken jejunal brush-border membrane by dietary methionineJuan F. Soriano-García, Mònica Torras-Llort, Miquel Moretó, and Ruth Ferrer1 December 1999 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 277, No. 6Effects of Oral Administration of Artificial Cells Immobilized Phenylalanine Ammonia-Lyase on Intestinal Amino Acids of Phenylketonuric Rats11 July 2009 | Biomaterials, Artificial Cells and Artificial Organs, Vol. 17, No. 2Increased neurotransmitter biosynthesis in phenylketonuria induced by phenylalanine restriction or by supplementation of unrestricted diet with large amounts of tyrosineEuropean Journal of Pediatrics, Vol. 148, No. 3The Regulation of Amino Acid and Sugar Absorption by Diet27 April 2009 | Nutrition Reviews, Vol. 42, No. 7Effects of Dietary Protein Level and Ascorbic Acid Supplementation on the Contents of Tyrosine Metabolites in Droppings and Plasma of Chicks Fed a Diet Containing Excess TyrosinePoultry Science, Vol. 62, No. 12Tyrosine supplementation in chronic experimental uremiaBiochemical Medicine, Vol. 30, No. 1Disorders of Nitrogen AbsorptionClinics in Gastroenterology, Vol. 11, No. 1Intensified gradients for endogenous amino acid substrates for transport system L on injecting a specific competitor for that systemLife Sciences, Vol. 29, No. 7Digestion in the pig between 7 and 35 d of age9 March 2007 | British Journal of Nutrition, Vol. 45, No. 2The regulation of amino acid transport in animal cellsBiochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, Vol. 515, No. 4Kinetics of the absorption of amino acids by the rat intestine in vivoBiochimica et Biophysica Acta (BBA) - Biomembranes, Vol. 512, No. 1Amino acid uptake in chickens subjected to increasing levels of quantitative food restriction9 March 2007 | British Journal of Nutrition, Vol. 38, No. 3Developmental patterns of intestinal transport mechanisms in the chickComparative Biochemistry and Physiology Part A: Physiology, Vol. 54, No. 1l-phenylalanine interactions with structurally related substances at the intestinal mucosaBiochemical Medicine, Vol. 11, No. 4Intestinal transport of aromatic amino acids, glucose and electrolytes in a patient with phenylketonuriaClinica Chimica Acta, Vol. 54, No. 3 More from this issue > Volume 223Issue 4October 1972Pages 788-793 Copyright & PermissionsCopyright © 1972 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1972.223.4.788PubMed4263024History Published online 1 October 1972 Published in print 1 October 1972 Metrics

RELATIONSHIP OF ELEVATED BLOOD TYROSINE TO THE ULTIMATE INTELLECTUAL PERFORMANCE OF PREMATURE INFANTS

Blood tyrosine concentrations were followed from birth to nursery discharge in 71 premature infants fed a high protein formula supplemented by 60 mg/day of ascorbic acid. In 89% of infants blood tyrosine concentrations were abnormal, and in 38% of infants the maximum level observed was 15.0 mg/100 ml or higher. Maximum blood tyrosine levels correlated significantly with gestational age (p = < 0.05) but not with birth weight. In a follow-up study performed at 15 months of age, infants with high tyrosine levels had no increase in the incidence of neurological abnormalities. Between 7 and 8 years of age a second follow-up study was performed on 62 children. This included a WISC, a Wide-Range Achievement Test (WRAT), and tests for psychomotor and language maturity. Two children had died in the interval, and five of the 62 were retarded for full testing. The full scale WISC I.Q. of all children correlated with birth weight at the 10% confidence level (p = < 0.1). The mean WISC I.Q. of high and low tyrosine subjects was 82.9 and 81.6 respectively. When infants were grouped by birth weight, a significant difference was detected in subjects weighing 2,000 gm or more. High tyrosine infants had a significantly lower performance I.Q. than low tyrosine infants (82.4 and 97.8 respectively; p = < 0.02). Significant differences were recorded in the scores on Object Assembly, Picture Assembly, and Picture Completion of the WISC. Significant differences were also seen on the Spelling subtest of the WRAT (p = < 0.02). We observed no adverse effect of high tyrosine levels on the intellectual performance of smaller premature infants, who on the whole have a greater risk for other complications of prematurity.

Elevated blood tyrosine in newborn infants

Es wird uber die Ergebnisse der routinemasigen Untersuchungen von Serumtyrosinspiegeln an Neugeborenen in Osterreich berichtet. Unter 135439 in einem Zeitraum von 19 Monaten im Durchschnittsalter von 5,5 Tagen getesteten Neugeborenen fanden sich 1357 (=1%) mit erhohten Tyrosinspiegeln (≧4 mg%). Davon hatten 54% ein Geburtsgewicht von mehr als 2500 g. Von starken Erhohungen waren Neugeborene mit niedrigem Geburtsgewicht wesentlich haufiger betroffen als normalgewichtige Neugeborene. Bei 60% der Neugeborenen mit erhohtem Tyrosinspiegel und Geburtsgewicht unter 1500 g lagen die Initialwerte uber 10 mg%, aber nur bei 8% der normalgewichtigen Neugeborenen mit Hypertyrosinamie. Bei Kontrolluntersuchungen nach Gabe von Vitamin C sind die Blutspiegel niedriger und die Zahl der Kinder mit normalem Blutspiegel groser als bei Untersuchungen ohne Vitamin C-Gabe. Die Tendenz zur Normalisierung des Tyrosinspiegels unter Vitamin C nimmt mit fallendem Geburtsgewicht deutlich ab. Untersuchungsbedingungen und Ergebnisse anderer Autoren werden mitgeteilt. Da Hypertyrosinamie bei Fruhgeborenen entgegen den bisherigen Ansichten moglicherweise doch zu Schadigungen fuhren kann, wird von Eiweiszufuhr von mehr als 4 g/kg/Tag bei Fruhgeborenen abgeraten.

A modified automated fluorometric method for the determination of tyrosine in blood and tissues, and its specificity

A modified version of the automated fluorometric determination of tyrosine by the nitrosonaphthol reaction is described, which was developed for the analysis of tyrosine in blood and tissues, and is simpler, more rapid, and more sensitive than earlier methods. Of the 50 compounds tested with this method, most of which were phenolic in structure, only para-substituted phenols with no other substituents in the aromatic ring, and 5-hydroxy indoles, gave appreciable fluorescence.

Effect of elevated blood tyrosine on intellectual development of premature infants

Blood tyrosines were followed from birth to nursery discharge in 71 premature infants fed a high-protein formula supplemented by 60 mg/day of ascorbic acid. In 89% tyrosine concentrations were abnormal, and in 38% the maximum observed was 5.0 mg% or higher. Maximum blood tyrosine correlated with gestational age (p < 0.05) but not with birth weight.On a follow-up study performed at 15 months, infants with high tyrosine levels had no increase in neurological abnormalities. Between 7 and 8 years a second follow-up was done on 64 children. This included a WISC and tests for psychomotor function. Two children had died in the interval and six others were too retarded for full testing. The full scale IQ of all children correlated with birth weight (p < 0.01). The mean IQ of high and low tyrosine subjects was 85.9 and 86.2, respectively. When infants were grouped by birth weight a significant difference was detected in subjects weighing 2000+ gm.Significant differences were recorded in scores on object assembly (p < 0.05), picture assembly (p < 0.05), and picture completion (p < 0.10). We observed no effect of high tyrosine levels on intellectual performance of smaller infants, who, on the whole, are a greater risk for other complications of prematurity.

The effect of Δ 1,6 tetrahydrocannabinol on biogenic amines and their amino acid precursors in the rat brain

Δ1,6 T.H.C. caused excitement followed by pronounced behavioural depression and catalepsy in rats when given at a dose of 100 mg/kg i.p. (Lower doses were less effective in producing these responses). Some 4 hr after administration, the animals became aggressive when disturbed. Ten hr after injection catalepsy was absent, the animals were slightly hyperactive-but no longer aggressive. Despite the pronounced behavioural changes caused byΔ1,6 T.H.C., the concentration and turnover of brain biogenic amines remained unaffected. There was a slight decrease in brain and blood tyrosine and in brain γ-aminobutyric acid levels.

L-(U-14C) tyrosine metabolism of the perfused cat brain with high plasma phenylalanine or without plasma tyrosine.

Cat brain perfusion was carried out with standard artificial blood containing 2 mg/dl of L-tyrosine and also with standard blood not containing tyrosine, for 70 minutes in each group. In addition, another group was perfused with the tyrosine-containing artificial blood plus 50 mg/dl of L-phenylalanine. Each of these experiments was conducted to see how such blood would affect the tyrosine metabolism of the brain. The results are summarized briefly. 1 Tn the perfusion without addition of tyrosine, the tyrosine content of the brain decreased markedly. Furthcr, there was an outflow of the brain tyrosine into the venous blood. The free tyrosine of the brain is mainly supplied from the blood tyrosine. 2 In the high plasma phenylalanine perfusion, the transport of the blood tyrosine into the brain was inhibited competitively by the blood phenylalanine, but output of tyrosine from the brain to the blood was not disturbed. 3 Tn the high plasma phenylalanine perfusion, the incorporation of tyrosinc into the brain protein fraction from the brain acid soluble fraction was lower than that ofthe control group. 4 During the high plasma phenylalanine perfusion, there was observed a marked increase of phenylalanine, and a decrease of tyrosine, threonine, isoleucine and leucine in the brain.

Transient Tyrosinemia in Full-Term Infants

Transient tyrosinemia has been found in approximately 1.8% of all infants in Massachusetts tested within the first 6 weeks of life (2,085 infants out of a total screened population of 117,752). About 24% have been full-term by weight and gestational criteria. In general, infants with lower birth weights had more marked tyrosinemia. However, several babies with average or above average birth weights had blood tyrosine concentrations of 10 mg/100 ml to more than 20 mg/100 ml, and in a few of these latter infants the tyrosinemia lasted as long as 9 to 13 weeks after birth. The infants have been clinically well.

Phenylalanine Tolerance Tests

The WIDESPREAD use of mass screening for blood phenylalanine among newborns has led to the recognition that in addition to phenylketonuria (PKU), 1 there may exist several closely related clinical and biochemical abnormalities, which have been variously labeled hyperphenylalaninemia associated with phenylalanine transaminase deficiency, 2 hyperphenylalaninemia, 3-5 phenylalaninemia, 6 and transient hyperphenylalaninemia. 7,8 This report describes the results of phenylalanine to tolerance tests performed during a collaborative study on the causes for high phenylalanine levels, associated with normal serum tyrosine, in newborn infant screening programs. Materials and Methods Definition of Cases. —The present survey covers the family members of all infants with persistent blood phenylalanine levels of 6 mg/100 ml or higher and with blood tyrosine levels less than 5 mg/100 ml, seen during 1964 to 1966, and in a few instances, during the first quarter of 1967, from 11 centers located in seven states (California, Colorado, Illinois, New

Manual Fluorometric Paper Disc Method for Determining Tyrosine in Blood

Abstract A spectrophotofluorometric method is described for the determination of tyrosine in blood dried on filter paper discs. It has been found that by immersing the paper disc containing the dried blood in aqueous trichloracetic acid, the blood proteins remain bound to the paper and the amino acid is eluted into the aqueous phase. This method of assay is based on the principle that tyrosine reacts with α-nitroso-β-naphthol to form a highly fluorescent product.