Fish odor syndrome: a case report of trimethylaminuria

Trimethylaminuria is a rare, autosomal recessive, metabolic disorder that results in accumulation of trimethylamine (TMA), which smells like rotten fish. The chemical is excreted in sweat and urine owing to a deficiency in the enzyme flavin monooxygenase 3 (FMO3). We report a case of trimethylaminuria in a 12-year-old girl. The patient failed treatment with diet and hygiene modification, but achieved symptomatic improvement after a four-month course of metronidazole.

CMO1 deficiency abolishes vitamin A production from beta-carotene and alters lipid metabolism in mice

Carotenoids are currently investigated regarding their potential to lower the risk of chronic disease and to combat vitamin A deficiency in humans. These plant-derived compounds must be cleaved and metabolically converted by intrinsic carotenoid oxygenases to support the panoply of vitamin A-dependent physiological processes. Two different carotenoid-cleaving enzymes were identified in mammals, the classical carotenoid-15,15'-oxygenase (CMO1) and a putative carotenoid-9',10'-oxygenase (CMO2). To analyze the role of CMO1 in mammalian physiology, here we disrupted the corresponding gene by targeted homologous recombination in mice. On a diet providing beta-carotene as major vitamin A precursor, vitamin A levels fell dramatically in several tissues examined. Instead, this mouse mutant accumulated the provitamin in large quantities (e.g. as seen by an orange coloring of adipose tissues). Besides impairments in beta-carotene metabolism, CMO1 deficiency more generally interfered with lipid homeostasis. Even on a vitamin A-sufficient chow, CMO1(-/-) mice developed a fatty liver and displayed altered serum lipid levels with elevated serum unesterified fatty acids. Additionally, this mouse mutant was more susceptible to high fat diet-induced impairments in fatty acid metabolism. Quantitative reverse transcription-PCR analysis revealed that the expression of peroxisome proliferator-activated receptor gamma-regulated marker genes related to adipogenesis was elevated in visceral adipose tissues. Thus, our study identifies CMO1 as the key enzyme for vitamin A production and provides evidence for a role of carotenoids as more general regulators of lipid metabolism.

Accumulation of glycinebetaine in rice plants that overexpress choline monooxygenase from spinach and evaluation of their tolerance to abiotic stress

BACKGROUND AND AIMS

Glycinebetaine (GB), a quaternary ammonium compound, is a very effective compatible solute. In higher plants, GB is synthesized from choline (Cho) via betaine aldehyde (BA). The first and second steps in the biosynthesis of GB are catalysed by choline monooxygenase (CMO) and by betaine aldehyde dehydrogenase (BADH), respectively. Rice (Oryza sativa), which has two genes for BADH, does not accumulate GB because it lacks a functional gene for CMO. Rice plants accumulate GB in the presence of exogenously applied BA, which leads to the development of a significant tolerance to salt, cold and heat stress. The goal in this study was to evaluate and to discuss the effects of endogenously accumulated GB in rice.

METHODS

Transgenic rice plants that overexpressed a gene for CMO from spinach (Spinacia oleracea) were produced by Agrobacterium-mediated transformation. After Southern and western blotting analysis, GB in rice leaves was quantified by (1)H-NMR spectroscopy and the tolerance of GB-accumulating plants to abiotic stress was investigated.

KEY RESULTS

Transgenic plants that had a single copy of the transgene and expressed spinach CMO accumulated GB at the level of 0.29-0.43 micromol g(-1) d. wt and had enhanced tolerance to salt stress and temperature stress in the seedling stage.

CONCLUSIONS

In the CMO-expressing rice plants, the localization of spinach CMO and of endogenous BADHs might be different and/or the catalytic activity of spinach CMO in rice plants might be lower than it is in spinach. These possibilities might explain the low levels of GB in the transgenic rice plants. It was concluded that CMO-expressing rice plants were not effective for accumulation of GB and improvement of productivity.

Diagnosis and management of trimethylaminuria (FMO3 deficiency) in children

Persistent trimethylaminuria in children is caused by autosomal recessively inherited impairment of hepatic trimethylamine (TMA) oxidation due to deficiency of flavin monooxygenase 3 (FMO3) secondary to mutations in the FMO3 gene. Trimethylaminuria or 'fish odour syndrome' is due to excessive excretion into body fluids and breath of TMA derived from the enterobacterial metabolism of dietary precursors. The disorder is present from birth but becomes apparent as foods containing high amounts of choline or of trimethylamine N-oxide (TMAO) from marine (sea or saltwater) fish are introduced into the diet. In our experience, trimethylaminuria (FMO3 deficiency) in children is rare. We have compared the dynamics and diagnostic efficacy of choline loading with marine fish meals in six children with trimethylaminuria. Loading with a marine fish meal provides a simple and acceptable method for confirmation of diagnosis of suspected trimethylaminuria in children, with the effects being cleared more quickly than with a choline load test. However, oral loading with choline bitartrate allows estimation of residual oxidative capacity in vivo and is a useful adjunct to molecular studies. Patients homozygous for the 'common' P153L mutation in the FMO3 gene showed virtual complete lack of residual TMA N-oxidative capacity, consistent with a nonfunctional or absent FMO3 enzyme, whereas a patient with the M82T mutation showed some residual oxidative capacity. A patient compound heterozygous for two novel mutations, G193E and R483T, showed considerable residual N-oxidative capacity. A further patient, heterozygous for two novel sequence variations in the FMO3 gene, consistently showed malodour and elevated urinary TMA/TMAO ratios under basal conditions but a negative response to both choline and marine fish meal loading. Comparison of the effects of administration of antibiotics (metronidazole, amoxicillin, neomycin) on gut bacterial production of trimethylamine from choline showed they all reduced TMA production to a limited extent, with neomycin being most effective. 'Best-practice' diagnostic and treatment guidelines are summarized.

[Alkaptonuria: a rare metabolic disorder. A report of two cases in siblings]

Alkaptonuria is a rare metabolic condition caused by congenital homogentisate oxidase deficiency of recessive inheritance. Homogentisate polymers are accumulated and cause urine darkening, brown pigmentation of connective tissue, articular cartilage pathology. The authors present clinical picture, pathogenesis, diagnostic and therapeutic possibilities in patients with alkaptonuria. Two siblings with alkaptonuria are described.

Trimethylamine and odorous sweat

Analysis of sweat collected from patients experiencing ichthyohidriosis, and from volunteers in whom this odour phenomenon had been artificially induced, showed that trimethylamine was the major causative factor.

[Ochronosis: a case report with multisystemic affectation, including pericardium]

Alkaptonuric ochronosis is rare disorder of tyrosin catabolism with an autosomal recessive trait. Alkaptonuric patients are deficient for homogentisate 1,2-dioxygenase. This enzymatic deficiency leads to the elimination of large amounts of homogentistic acid in the urine (Alkaptonuria) with accumulation of homogentistic acid oxidized pigment in the connective tissue (Ochronosis). The most common clinical features are dark brown discoloration of urine on exposure to air; ocular and cutaneous pigmentation; calcification of the intervertebral disc and cardiovascular ochronosis, especially calcification and stenosis of the aortic valve. The diagnosis is confirmed by detection of homogentistic acid in urine. We report a case of a 87 year old female which has all these clinical features mentioned above and pericardiac calcification, which had not been previously reported, to our knowledge.

Exacerbation of the ochronosis of alkaptonuria due to renal insufficiency and improvement after renal transplantation

In alkaptonuria, homogentisate 1,2-dioxygenase deficiency causes tissue accumulation of homogentisic acid (HGA), followed by signs and symptoms of ochronosis. These include massive urinary excretion of HGA, arthritis and joint destruction, pigmentation of cartilage and connective tissue, and cardiac valve deterioration. We describe a 46-year-old man with alkaptonuria and diabetic renal failure whose plasma HGA concentration was twice that of any other alkaptonuria patient, and whose ochronosis progressed much more rapidly than that of his two alkaptonuric siblings. After renal transplantation, the plasma HGA normalized, and the daily urinary excretion of HGA decreased by 2-3g. This case illustrates the critical role of renal tubular secretion in eliminating HGA from the body, and suggests that renal transplantation in a uremic patient not only restores HGA excretion, but may also provide homogentisate 1,2-dioxygenase activity for the metabolism of HGA.

[Diagnostic image (45). Ochronosis]

In a 70-year-old woman, in whom ochronosis (alkaptonuria) was diagnosed at the age of 54, bluish discolouration of the cartilage of the ears was observed.

Abnormalities of flavin monooxygenase as an etiology for sideroblastic anemia

We postulated that a deficiency of flavin monooxygenase (FMO)-a ferrireductase component of cells-could produce sideroblastic anemia. FMO is an intracellular ferrireductase which may be responsible for the obligatory reduction of ferric to ferrous iron so that reduced iron can be incorporated into heme by ferrochelatase. Abnormalities of this mechanism could result in accumulation of excess ferric iron in mitochondria of erythroid cells to produce ringed sideroblasts and impair hemoglobin synthesis. To investigate this hypothesis we obtained blood from patients with sideroblastic anemia and normal subjects. Extracts of peripheral blood lymphocytes were used to measure ferrireduction by utilization of NADPH. Lymphoid precursors are reported to accumulate iron in mitochondria similarly to erythroid precursors. Utilization of lymphoid precursors avoided the need for bone marrow aspirations. We studied three patients with sideroblastic anemia. One patient and his asymptomatic daughter had a significant decrease in ferrireductase activity. They also had markedly diminished concentrations of FMO in lymphocyte protein extracts on Western blots. This was accompanied by increased concentration of mobilferrin in the extracts. These results suggest that abnormalities of FMO and mobilferrin may cause sideroblastic anemia and erythropoietic hemochromatosis in some patients.

Crystal structure of human homogentisate dioxygenase

Homogentisate dioxygenase (HGO) cleaves the aromatic ring during the metabolic degradation of Phe and Tyr. HGO deficiency causes alkaptonuria (AKU), the first human disease shown to be inherited as a recessive Mendelian trait. Crystal structures of apo-HGO and HGO containing an iron ion have been determined at 1.9 and 2.3 A resolution, respectively. The HGO protomer, which contains a 280-residue N-terminal domain and a 140-residue C-terminal domain, associates as a hexamer arranged as a dimer of trimers. The active site iron ion is coordinated near the interface between subunits in the HGO trimer by a Glu and two His side chains. HGO represents a new structural class of dioxygenases. The largest group of AKU associated missense mutations affect residues located in regions of contact between subunits.

Identification of the mutation in the alkaptonuria mouse model. Mutations in brief no. 216. Online

Alkaptonuria (aku), an inborn error of metabolism caused by the loss of homogentisate 1,2-dioxygenase (HGD), has been described in a mouse model created by ethylnitrosourea mutagenesis but the mutation in these mice has not previously been identified. We used RT-PCR to amplify the Hgd cDNA from Hgd(aku)/Hgd(aku) mice. Two products shorter than the wild-type product were amplified. Restriction mapping and DNA sequencing were then used to identify the Hgd(aku) mouse mutation, found to be a single base change in a splice donor consensus sequence, causing exon skipping and frame-shifted products. This base change allowed us to create a non-radioactive genotyping assay for this allele.

Mild trimethylaminuria caused by common variants in FMO3 gene

Mild to transient trimethylaminuria is caused by common variants in the FMO3 gene leading to greatly reduced enzyme activity in vivo. FMO3 deficiency may have clinical relevance well beyond unpleasant body odour.

Molecular defects in alkaptonuria

At the dawn of human genetics Sir Archibald Garrod used alkaptonuria as a paradigm to demonstrate the applicability of the Mendelian laws to men and to develop the concept of inborn errors of metabolism. The human cDNA for homogentisate 1,2 dioxygenase was identified due to its homology to the corresponding mouse enzyme and was screened for mutations in alkaptonuric patients from Slovakia. Homozygous mutations were found in four unrelated families and their segregation with the disease was demonstrated. One of the mutations, observed in two families, leads to a frame-shift and thus is unlikely to produce functional protein. The data formally establish the homogentisate 1,2 dioxygenase gene (HGD) as the molecular cause of alkaptonuria and allow for the development of molecular carrier tests in populations at risk.

Accumulation of the angucycline antibiotic rabelomycin after disruption of an oxygenase gene in the jadomycin B biosynthetic gene cluster of Streptomyces venezuelae

DNA from a region downstream of and overlapping the polyketide synthase (PKS) gene cluster for jadomycin B biosynthesis in Streptomyces venezuelae was cloned and sequenced. Analysis of the nucleotide sequence located one complete ORF (ORF6), an incomplete one representing the 3' region of ORF4 in the PKS cluster, and a second incomplete one (ORF7). The deduced amino acid sequences for ORFs 6 and 7 resemble those of oxygenases. Since a plausible biosynthetic pathway for jadomycin B includes an angular polyketide intermediate that undergoes oxidative ring fission before condensation with an amino acid, we subcloned one of the presumptive oxygenase genes (ORF6) in a segregationally unstable shuttle vector (pHJL400) and disrupted it by inserting the gene for apramycin resistance. Transformation of S. venezuelae with the disruption vector and selection for apramycin resistance gave mutants blocked in jadomycin biosynthesis. Southern hybridization confirmed that gene replacement had occurred. Cultures of the mutants accumulated a metabolite identified by comparison with an authentic sample as rabelomycin, a non-nitrogenous polyketide-derived antibiotic originally isolated from Streptomyces olivaceus.

Male pseudohermaphroditism resulting from 17 alpha-monooxygenase (P-450C17) deficiency in two unrelated Guamanians

OBJECTIVE

To report the cases of and to describe two unrelated Guamanian patients with an unusual form of congenital adrenal hyperplasia resulting from 17 alpha-monooxygenase deficiency (P-450C17).

DESIGN

Patient series.

SETTING

Referral center.

PATIENTS

Two phenotypic females of Guamanian descent, unrelated, and referred for evaluation of hypertension and delayed sexual development.

INTERVENTIONS

Diagnosis by measurement of specific adrenocortical precursors and initiation of therapy with dexamethasone. Documentation of response by decrease in circulating concentrations of metabolites and decrease in blood pressure.

CONCLUSIONS

The finding of a rare autosomal recessive disorder in two unrelated persons from a small genetic pool in Guam suggests that this may result from the same molecular defect and may be present in this population at an unexpectedly high incidence. Lack of suspicion frequently leads to unnecessary delay in diagnosis of this condition.

Ochronosis: a report of a case and a review of literature

A patient with alkaptonuria and ochronotic pigment deposited in articular cartilage and sclerae clinically manifested a serious osteoarthritis of the peripheral and axial joints and synchondrosis, typically involved in long lasting cases of this hereditary defect of homogentisic acid oxidase. This is the first patient with this disorder reported, where a non-cemented total knee prosthesis (PCAR) was applied on both knees. This was possible due to the good quality of the bone stock, which did not seem to be impaired by ochronosis. Our patient had no cardiac symptoms or murmurs, but had a slight calcification in the annulus of aorta observed with echocardiography, a useful new method for screening this disease manifestation. A third new aspect reported is the immunopathology of the synovial tissue. Small pieces of torn-off cartilage were seen embedded in the synovial stroma. This was associated with a slight hyperplasia of the C3bi-receptor positive and proline hydroxylase positive type A and B synovial lining cells. Perivenular infiltrates contained CD2 positive T lymphocytes, mostly belonging to the CD4 subset, and some C3bi-receptor positive monocytes. Activated CD25 positive and immunoglobulin light chain positive T and B lymphocytes were absent or few. Because modern medicine has much to offer to those suffering from this ancient inborn error of metabolism in the form of new specific diagnostic methods and new surgical modes of treatment, such as endoprosthesis surgery and cardiac valve replacement, we also present a literature overview of this interesting condition.

Hallervorden-Spatz disease: cysteine accumulation and cysteine dioxygenase deficiency in the globus pallidus

We describe neurochemical abnormalities found in the brains of 2 patients with autopsy-confirmed Hallervorden-Spatz (HS) disease. In 1 patient, contents of cystine and of glutathione-cysteine mixed disulfide in the globus pallidus were markedly elevated above values for appropriate control subjects. Activity of cysteine dioxygenase, which converts cysteine to cysteine sulfinic acid, was reduced in the globus pallidus, but normal in the frontal cortex and putamen of both patients. gamma-Aminobutyric acid content was markedly decreased in the globus pallidus and substantia nigra of both patients. These results suggest that cysteine accumulates locally in the globus pallidus in Hallervorden-Spatz disease as a result of an enzymatic block in the metabolic pathway from cysteine to taurine. Accumulated cysteine may chelate iron, accounting for the local increase in iron content in Hallervorden-Spatz disease. The combined excess of cysteine and ferrous iron may generate free radicals that damage neuronal membranes to cause the typical morphological changes observed in this disorder.

Enzyme defect in a case of tyrosinemia type I, acute form

We determined the activities of tyrosine aminotransferase (TAT, EC 2.6.1.5), p-hydroxyphenylpyruvate oxidase (p- HPPA oxidase, EC 1.14.2.2) and fumarylacetoacetate fumarylhydrolase ( FAH , EC 3.7.12) in cytosol of the liver and kidney tissues obtained at autopsy from a case of hereditary tyrosinemia type I. Values were compared with those from a control group of autopsied tissues from three adults and six children, who had died of other causes. In tyrosinemia, these three hepatic enzyme activities were all decreased: TAT showed approximately 35%, p- HPPA oxidase 11%, and FAH 60% of the corresponding control values. On the other hand, kidney enzymes in tyrosinemia revealed that FAH was most significantly decreased to approximately 14% of the control activity. Km values for substrate--determined for p- HPPA oxidase and FAH --were not different between the patient and controls, suggesting no altered properties of these enzymes. We conclude that in the present case of hereditary tyrosinemia type I, the activities of p- HPPA oxidase in liver and FAH in kidney were most strikingly affected. This fact may in part explain the deteriorated metabolism of tyrosine observed in this patient.

Hepatic monooxygenase activities in subjects with a genetic defect in drug oxidation

Microsomes were prepared from surgical wedge biopsy specimens of the livers of 49 patients and from intact liver lobes of 9 kidney transplant donors with the objective of defining interindividual differences in the content and activities of six monooxygenase activities and their relationship to a common genetic defect in drug metabolism known as "debrisoquine polymorphism." Sixty-one patients were phenotyped in vivo with respect to their urinary metabolic ratio of debrisoquine to 4-hydroxydebrisoquine. Forty-seven patients were found to be extensive metabolizers, 12 patients were arbitrarily classified as "intermediate" metabolizers, and only 2 patients were poor metabolizers. The formation of the 4-hydroxy metabolite from debrisoquine in hepatic microsomes from extensive metabolizers was 1.33 +/- 0.437 nmol . mg protein-1 . 15 min-1 (mean +/- SD, n = 9). Microsomes of the 2 poor metabolizers formed 0.13 and 0.18 nmol 4-hydroxydebrisoquine . mg-1 . 15 min-1. Microsomes of intermediate metabolizers produced 0.464 +/- 0.115 (n = 5) of 4-hydroxydebrisoquine and were distinguished from extensive and poor metabolizers. There was no correlation between the capacity for debrisoquine hydroxylation and the total concentration of microsomal cytochrome P450, cytochrome b5, or the activities of nicotinamide adenine dinucleotide phosphate-cytochrome c reductase, aminopyrine-N-demethylase, aryl hydrocarbon hydroxylase, ethoxycoumarin-O-deethylase, aldrin epoxidase, and 2-biphenylhydroxylase. These studies indicate that genetically defective in vivo metabolism of debrisoquine is caused by a deficiency of a monooxygenase reaction in liver microsomes. Moreover, the findings suggest that direct measurement of the debrisoquine oxidation deficiency may allow the identification of heterozygous carriers of the defect. This conclusion remains to be verified by pedigree analysis.

Four-hydroxyphenylpyruvic acid oxidase deficiency with normal fumarylacetoacetase: a new variant form of hereditary hypertyrosinemia

Enzymatic studies on the liver of an infant are described-a case of hypertyrosinemia without hepatic dysfunction. His parents were siblings and the mother had hypertyrosinemia. Excessive amounts of 4-hydroxyphenylpyruvic acid (pHPP), 4-hydroxyphenylacetic acid (pHPL), and 4-hydroxyphenylacetic acid (pHPA) were found to be excreted in the patient's urine as well as in the urine of the mother and the inhibitor of porphobilinogen synthetase was not found. Soluble tyrosine aminotransferase (s-TAT), separated from that of the mitochondrial form (m-TAT) by DE 52 column chromatography, was normal in the patient's liver, both quantitatively and qualitatively. The activities of fumarylacetoacetase in the patient's liver and in the peripheral leucocytes from the parents were normal. The activity of pHPP oxidase in the patient's liver was approximately 5% of the control and the enzyme had a high Km value for pHPP (controls: 0.06 +/- 0.01 mM, patient: 0.23 +/- 0.03 mM). From these results, the patient was thought to be different from previously described types of tyrosinemia and perhaps representative of a new variant form. This is the first report concerning 4-hydroxyphenylpyruvic acid oxidase deficiency alone. Mild metal retardation and mild hypertyrosinemia may be offered as typical clinical features of the disease.

Epinephrine potentiation of arachidonate-induced aggregation of cyclooxygenase-deficient platelets

Evaluation of platelet physiology, biochemistry, ultrastructure, and function in a young woman without history of hemorrhagic problems revealed that her platelets were deficient in cyclooxygenase activity. Her citrate platelet-rich plasma (C-PRP) responded monophasically when stirred with aggregating agents in the same manner as aspirin-treated normal C-PRP, but could be irreversible aggregated by high concentrations of thrombin, collagen, and ADP. Her platelets did not aggregate when stirred with AA at concentrations as high as 2 mM. Ultrastructure and levels of serotonin and adenine nucleotides wer normal. Amounts of 14C-AA released after stirring with thrombin were similar to normal cells. However, evaluation of prostaglandin synthesis after stirring with 14C-AA revealed no evidence of endoperoxide or thromboxane production, although products of the lipoxygenase pathway were produced in normal amounts. Aggregation in response to AA was completely corrected after mixing with 10% normal C-PRP. However, equal volumes of her C-PRP and normal aspirin-treated C-PRP did not respond to AA, whereas 10% normal platelets combined with aspirin-treated cells corrected aggregation to AA. Since epinephrine pretreatment corrects the response of dog platelets that are not aggregated by AA, we evaluated the influence of epinephrine on her platelets. Preexposure to 5 micro M epinephrine, a concentration that gave only primary waves of aggregation, resulted in normalization of her response to AA, even though correction was not associated with the generation of endoperoxides or thromboxanes. The results may explain why patients with platelet cyclooxygenase deficiency have mild or absent bleeding symptoms.

[Association, in the same subject, of deletion of the short arm of chromosome 4 (4p-) and of complete deficiency of parahydroxyphenyl-pyruvate oxidase activity in the liver (tyrosinosis)]

The authors report the association in a child of monosomy 4p- and tyrosinosis. They discuss the localization of the para-hydroxyphenylpyruvate oxidase locus on the short arm of chromosome 4. They suggest the study of para-hydroxyphenylpyruvate oxidase activity in each child with monosomy 4p-.

Congenital deficiency of cyclo-oxygenase in a woman with generalized atherosclerosis

The case of a 52-year-old woman with congenital cyclo-oxygenase deficiency, signs of generalized atherosclerosis and a moderate bleeding tendency is reported. Secondary platelet aggregation was absent. Platelet aggregation induced by arachidonic acid failed totally while that induced by calcium ionophore was normal. No malondialdehyde formation could be detected in her platelet-rich-plasma. The life-long deficiency of cyclo-oxygenase had not protected her from progressive vascular disease. This case suggests that the chronic intake of large doses of aspirin cannot prevent arterial disorders.

Congenital deficiency of thromboxane and prostacyclin

Animal work suggests that with certain doses of aspirin the antithrombotic effect exerted via the inhibition of the proaggregatory platelet thromboxane A2 (TXA2) may be neutralised by the concomitant vascular reduction of the antiaggregatory prostacyclin (PGI2). Such a situation might result not only in therapeutic ineffectiveness but also in a thrombotic tendency. A patient with a bleeding disorder characterised by a mildly prolonged bleeding time and defective platelet-release reaction due to a congenital deficiency of cyclo-oxygenase provided an opportunity for studying this problem. Her platelets did not aggregate with arachidonic acid, but they did so with a synthetic endoperoxide analogue. Thrombin added to her platelet-rich plasma and whole blood did not generate thromboxane B2 (TXB2). Washed platelets, when incubated with 14C-arachidonic acid, did not produce the cyclo-oxygenase metabolites. A biopsy specimen of her vein did not generate PGI2, as measured both by platelet-aggregation inhibition and radioimmunoassay of 6-keto-PGF1 alpha. Clinically, the patient had a mild bleeding tendency but no thrombotic problems. The findings suggest that in man aspirin therapy, even at doses which inhibit PGI2 formation, would only impair haemostasis mildly without producing a thrombotic tendency.

Dietary treatment of tyrosinemia type I: importance of methionine restriction

A patient with tyrosinemia type I was treated with formula 3200 AB. This dietary approach lowered the elevated plasma phenylalanine and tyrosine levels but failed to eliminate the hypermethioninemia and the concomitant clinical abnormalities of ascites and other abnormal liver functions. Strict control of dietary intake of methionine, as well as phenylalanine and tyrosine, by a synthetic amino acid mixture or by a combination with formula 3200 AB maintained all plasma amino acids within the normal limits, permitted normal physical growth, and eliminated all hepatic and renal abnormalities. We suggest that restriction of only phenylalanine and tyrosine is inadequate in treating tyrosinemia type I during the acute phase. In such cases, the dietitian should use 3200 AB formula with caution until the acute phase of the disease subsides and plasma methionine levels return to normal.

A new sulfur amino acid, named hawkinsin, identified in a baby with transient tyrosinemia and her mother

An unknown compound present in the urine of a girl with prolonged transient tyrosinemia and her mother was isolated and identified as (2-L-cystein-S-yl-1,4-dihydroxycyclohex-5-en-1-yl)-acetic acid (IVa). The new amino acid was named hawkinsin (Haw) and characterized by gas chromatography-mass spectrometry (GC-MS) of its penta-trimethylsilyl (TMS) derivative and of its desulfuration components. Haw was compared with the synthetic reference compound using GC-MS, IR, TLC, PC, ion-exchange chromatogrpahy and high-voltage electrophoresis. IVa and (2,6-bis-L-cystein-S-yl-1,4-dihydroxycyclohexyl-1)-acetic acid were synthesized from 4-quinolacetic acid, the latter was prepared in two different ways. It is postulated that Haw originates from an intermediate in the 4-hydroxy-phenylpuruvate hydroxylase reaction (EC 1.14.2.2), and that mother and child are heterozygous for an inborn error of metabolism characterized by a defect in this hydroxylase system, which is unable to rearrange the intermediate to homogentisic acid.

Urinary p-tyramine in hereditary tyrosinemia: II. Origin of urinary p-tyramine

1. A patient with hereditary tyrosinemia (tyrosinosis) was given oral loads of p-tyramine and tyrosine with and without medication (neomycin) to investigate the respective roles of intestinal bacteria and tissues in accounting for the origin of urinary p-tyramine. 2. The excretion of a high circulating level of p-tyramine following an oral load of p-tyramine in a patient with hereditary tyrosinemia (tyrosinosis) was as conjugated p-hydroxyphenylacetic acid (p-HPAA) and conjugated p-tyramine. 3. Both intestinal bacterial activity and tissue decarboxylation appeared to account for urinary p-tyramine in this patient following an oral load of tyrosine. 4. Sterilization of the gut by oral neomycin and a second load of oral tyrosine further supported a predominate role for tissue decarboxylation in the origin of urinary p-tyramine. 5. The data suggested that a major route of tyrosine metabolism in man may be via tissue decarboxylation of tyrosine.

Urinary p-tyramine in hereditary tyrosinemia: I. Levels as compared to normal individuals, effect of diet, and relationship to urinary tyrosine

1. A 40-fold increase in urinary p-tyramine was observed in a patient with hereditary tyrosinemia as compared to a control population. 2. The excretion of urinary-free p-tyramine was decreased with the restriction of oral phenylalanine and tyrosine in this patient. The pattern of urinary tyrosine and urinary-free p-tyramine was similar during the period of normal protein diet and restricted diet of phenylalanin and tyrosine. 3. The pattern of urinary-free p-tyramine and tyrosine following oral loads of tyrosine and phenylalanine was similar except for a lag period before a tyramine response was observed. 4. The possibility of the patient with hereditary tyrosinemia providing a model to study the origin of urinary p-tyramine is discussed.

Mitochondrial proline dehydrogenase deficiency in hyperprolinemic PRO/Re mice: genetic and enzymatic analyses

Genetic analyses, involving backcross and F2 matings, demonstrate that the type I hyperprolinemia of PRO/Re mice is caused by an abnormal allelet at a single locus designated pro-1. Mice homozygous for this allele (pro-1b/pro-1b) posses a deficiency in the activity of component 1 of mitochondrial proline dehydrogenase. In liver mitochondria of normal C57BL/6J mice, two proline dehydrogenase activity components are demonstrable by electrophoretic resolution of Triton X-100 solubilized extracts. In mitochondria of PRO/Re mice, the activity of component 1 is not readily detectable. Residual proline dehydrogenase activity in PRO/Re mitochondria appears, therefore, to be due in large measure to activity component 2 which is more stable to incubation at 40 C, exhibits slower electrophoretic mobility, and is less reactive to menadione. Kinetic analyses demonstrate a Km (proline) for the Triton X-100 solubilized enzyme activities of PRO/Re and C57BL/6J liver mitochondria of 0.4 M and 2.9 X 10(-3) M, respectively. C57BL/6J enzyme activity is inhibited by high substrate concentration. The actins of PRO/Re liver obtained by differential centrifugation. Abnormal control of respiratory chain function in PRO/Re mitochondria appears to involve primarily proline oxidation, as indicated by the level of activity of several inner membrane enzymes.