Ornithine Levels Research Articles

Changes in the Plasma Amino Acid Profile in Anorexia Nervosa

We evaluated and measured by high performance liquid chromatography the plasma amino acid levels in 11 female patients with anorexia nervosa during a period of significant loss of body weight, compared with 11 healthy age-matched controls. Total amino acid and total branched-chain amino acid levels were similar in both groups, however significantly higher levels of glycine and ornithine were found in anorexia nervosa patients, as well as significantly lower levels of leucine, tyrosine and lysine compared with controls. The glycine/valine and phenylalanine/tyrosine ratios were significantly higher in anorexia nervosa patients than in control subjects. The levels and ratios of other amino acids were within the normal range, with no significant differences between the two groups. Changes in the plasma amino acid profile in anorexia nervosa patients can be explained by chronic severe malnutrition and prolonged stress.

Quantitative trait transcripts for nicotine resistance in Drosophila melanogaster

Although most genetic association studies are performed with the intention of detecting nucleotide polymorphisms that are correlated with a complex trait, transcript abundance should also be expected to associate with diseases or phenotypes. We performed a scan for such quantitative trait transcripts in adult female heads of the fruit fly (Drosophila melanogaster) that might explain variation for nicotine resistance. The strongest association was seen for abundance of ornithine aminotransferase transcripts, implicating detoxification and neurotransmitter biosynthesis as mediators of the quantitative response to the drug. Subsequently, genetic analysis and metabolite profiling confirmed a complex role for ornithine and GABA levels in modification of survival time upon chronic nicotine exposure. Differences between populations from North Carolina and California suggest that the resistance mechanism may be an evolved response to environmental exposure.

Intermediate metabolism in association with the amino acid profile during the third trimester of normal pregnancy and diet-controlled gestational diabetes

The aim of this study was to investigate the levels of fasting maternal plasma amino acids in normal pregnant women and compare them with those in gestational diabetes controlled by diet only. We also wished to delineate the alterations occurring in intermediate metabolic pathways in gestational diabetes. Forty-six (64.7%) pregnant women with uncomplicated pregnancy (NP group) and 25 (35.2%) women with gestational diabetes mellitus (GDM group) at 30-33 weeks of gestation participated in the study. Fasting maternal plasma carnitine (total, free, and acyl-carnitine), beta-hydroxybutyrate, free fatty acids, glycosylated hemoglobin, and 21 amino acids were assayed. Fasting carnitine esters exhibited lower levels in the GDM group (P = .03). Higher levels of fasting beta-hydroxybutyrate and free fatty acids (P < .001 and .02, respectively) were observed in the GDM group. Of the 21 amino acids, only methionine, glycine, alanine, citrulline, and ornithine levels were found at significantly higher levels in the NP group (P = .03, P < .001, P = .01, P < .001, and P < .001, respectively). In gestational diabetes, ketogenic amino acids and the branched-chain amino acid isoleucine are released at low rates from skeletal muscle and are mostly catabolized in the liver rather than in peripheral tissues. In contrast, in normal pregnancy proteinolysis is enhanced, and the ketogenic amino acids along with branched-chain amino acids are catabolized in both the liver and peripheral tissues. As a result, ketogenic amino acids are fully oxidized and gluconeogenesis becomes more efficient, whereas urea cycle operates at a higher rate.

Pulmonary Hypertension in Thalassemia: Association with Hemolysis, Arginine Metabolism Dysregulation, and a Hypercoagulable State

Pulmonary Hypertension in Thalassemia: Association with Hemolysis, Arginine Metabolism Dysregulation, and a Hypercoagulable State

Diabetes‐induced reduction in renal medullary nitric oxide (NO) and oxygen tension (pO 2 ) due to increased hepatic arginine metabolism and oxidative stress

Arginine availability as regulator of NO bioavailability has gained growing interest. We hypothesized that diabetes would induce NO deficiency in the renal medulla, with subsequent reduction in pO2, due to arginine limitation for NO production. Medullary NO, pO2 and blood flow were measured in control and streptozotocin-induced diabetic rats, with or without α-tocopherol treatment, during acute iv infusion of L-arginine followed by L-NAME. Components of the arginine metabolism were also investigated. Both untreated and tocopherol-treated diabetic rats had reduced NO compared to controls (59±4, n=10 and 67±7, n=7 vs. 122±7 nmol/l, n=8, respectively). Arginine increased NO in diabetic rats and not in controls, and totally restored NO in tocopherol-treated animals. Although blood flow increased equally in all groups, arginine selectively increased pO2 in diabetic rats. Diabetes decreased plasma arginine and ADMA concentrations, but increased hepatic CAT-2A and ornithine levels independent of tocopherol treatment. In conclusion, diabetic rats had reduced renomedullary NO and pO2, which was independent of hemodynamic changes but related to decreased plasma arginine due to increased hepatic arginine metabolism. Reduced oxidative stress augmented the NO response, but did not fully restore NO levels. These changes may be important factors for the development of diabetes-induced renal dysfunction.

Liver I/R injury is improved by the arginase inhibitor, Nω-hydroxy-nor-l-arginine (nor-NOHA)

Liver ischemia-reperfusion (I/R) injury is associated with profound arginine depletion due to arginase release from injured hepatocytes. The purpose of this study was to determine whether arginase inhibition with N(omega)-hydroxy-nor-l-arginine (nor-NOHA) would increase circulating arginine levels and decrease hepatic damage during liver I/R injury. The effects of nor-NOHA were initially tested in normal animals to determine in vivo toxicity. In the second series of experiments, orthotopic syngeneic liver transplantation (OLT) was performed after 18 h of cold ischemia time in Lewis rats. Animals were given nor-NOHA (100 mg/kg) or saline before and after graft reperfusion. In normal animals treated with nor-NOHA, there were no histopathological changes to organs, liver enzymes, serum creatinine, or body weight. In the OLT model, animals treated with saline exhibited markedly elevated serum transaminases and circulating arginase protein levels. Nor-NOHA administration blunted the increase in serum arginase activity by 80% and preserved serum arginine levels at 3 h after OLT. Nor-NOHA treatment reduced post-OLT serum liver enzyme release by 50%. Liver histology (degree of necrosis) in nor-NOHA-treated animals was markedly improved compared with the saline-treated group. Furthermore, use of the arginase inhibitor nor-NOHA did not influence polyamine synthesis owing to the decrease in ornithine levels. Arginase blockade represents a potentially novel strategy to combat hepatic I/R injury associated with liver transplantation.

Controlled study of enteral arginine supplementation in burned children: impact on immunologic and metabolic status

Objective We compared the effects of an arginine-supplemented diet with those of an isocaloric isonitrogenous diet on immune and metabolic response of children with burns. Methods This was a double-blind, randomized, placebo-controlled trial in a burn treatment center of a pediatric hospital in Santiago, Chile. All children (1–5 y of age) admitted within 48 h of a moderate to deep burn injury covering 10% to 40% of total body surface area were evaluated. Twenty-eight children met the criteria and were randomly assigned to receive an arginine-supplemented diet (AG; n = 14) or an isocaloric isonitrogenous diet (CG; control, n = 14) for 14 d. Samples were collected at admission (baseline) and on days 7 and 14 for lymphoproliferative response to mitogens, plasma interleukins (interleukin-1, interleukin-6, tumor necrosis factor-α), plasma arginine and ornithine levels, serum C-reactive protein, prealbumin, albumin, glucose, and total urinary nitrogen. Results The AG enhanced lymphoproliferative responses (analysis of variance, P < 0.05), which were 72% of normal at baseline in both groups; by day 7 responses increased to 144% in the AG group and decreased to 56% in the CG group; both groups returned to normal by day 14. Baseline interleukin-6 was significantly increased in all children. There were no differences in plasma concentrations of interleukin-1, interleukin-6, tumor necrosis factor-α, C-reactive protein, prealbumin, albumin, or glucose between the AG and CG groups. On day 7 plasma ornithine levels increased significantly in the AG versus CG group ( P < 0.05); arginine levels showed no change. Conclusions An exclusively AG improves mitogen-stimulated lymphocyte proliferation in burned children. The benefits of arginine for the immune system do not appear to be related to a metabolic response. The biological significance of this finding remains to be determined.

Osteoporosis Associated with Gyrate Atrophy: a Case Report

Gyrate atrophy (GA) is a rare degenerative, hereditary disease characterized by markedly high serum ornithine levels resulting from the deficiency of ornithine-delta-amino transferase (OAT), a mitochondrial matrix enzyme. Hyperornithinaemia is accompanied by lysinuria and reduced lysine plasma levels in GA. Type I collagen is known to play a role in osteoporosis pathogenesis. Lysine has a role in cross ligament formation of type I collagen, a bone matrix element, and thus, in bone strength. Although the most common complaint in GA is visual problems, the disease may include muscle involvement, as well. Reduced physical activity resulting from muscle involvement and hypolysinemia in GA may lead to osteoporosis. However, there is no data in the literature concerning the relation between GA and osteoporosis. In this report a GA case with early osteoporosis, besides visual deterioration and muscular signs, is reported, and the relation between GA and osteoporosis is emphasized for the first time.

Ornithine deficiency in the arginase double knockout mouse

Knockout mouse models have been created to study the consequences of deficiencies in arginase AI and AII, both individually and combined. The AI knockout animals die by 14 days of age from hyperammonemia, while the AII knockout has no obvious phenotype. The double knockout (AI −/−/AII −/−) exhibits the phenotype of the AI-deficient mice, with the additional absence of AII not exacerbating the observed phenotype of the AI knockout animals. Plasma amino acid measurements in the double knockout have shown arginine levels increased roughly 100-fold and ornithine decreased roughly 10-fold as compared to wildtype. Liver ornithine levels were reduced to 2% of normal in the double knockout with arginine very highly elevated. Arginine and ornithine were also altered in other tissues in the double knockout mice, such as kidney, brain, and small intestine. This is the first demonstration that the fatal hyperammonemia in the AI knockout mouse is almost certainly due to ornithine deficiency, the amino acid needed to drive the urea cycle. Others have shown that the expression of ornithine aminotransferase (OAT) rapidly decreases in the intestine at the same age when the AI-deficient animals die, indicating that this enzyme is critical to the maintenance of ornithine homeostasis, at least at this early stage of mouse development. Although most human AI-deficient patients have no symptomatic hyperammonemia at birth, it is possible that clinically significant ornithine deficiency is already present.

Infected Chronic Wounds Show Different Local and Systemic Arginine Conversion Compared With Acute Wounds

Several experimental studies have shown the importance of arginine in wound healing. However, little is known about its role in human wound healing. In this study, we investigated arginine metabolism in impaired wound healing. Twenty patients with chronic wounds and 10 patients with acute wounds were included in a prospective study. Amino acids, nitrate/nitrite, and arginase concentrations were determined in plasma and wound fluid using high-performance liquid chromatography and enzyme-linked immunosorbent assay. Chronic wounds were divided into two groups: noninfected chronic wounds (n = 11) and infected chronic wounds (n = 9), based on quantitative bacterial analysis of wound fluid samples. Plasma arginine levels, next to total plasma amino acid levels, were significantly decreased in patients with infected chronic wounds compared with patients having acute or noninfected wounds. Citrulline and ornithine levels were significantly increased in infected chronic wounds and related to decreased nitrate/nitrite levels, whereas wound fluid arginine levels were similar in all groups. In addition, wound fluid arginase levels of infected chronic wounds were significantly enhanced. This study demonstrates that patients with infected chronic wounds have decreased plasma arginine levels and suggests enhanced arginine conversion in the wound. In contrast to noninfected chronic wounds, arginine seems to be mainly metabolized by arginase in infected chronic wounds. In conclusion, our hypothesis is that impaired wound healing is related to an altered arginine usage.

Ornithine alpha-ketoglutarate increases mineralization and mechanical properties of tibia in turkeys

Skeletal disorders in rapidly growing poultry are commonplace. This study was performed to investigate the effect of ornithine alpha-ketoglutarate (OKG) administration during the last 7 weeks of life on structural properties, mineralization, and mechanical endurance of skeleton in turkeys at slaughter. Healthy HB Medium Bronze female turkeys were randomly assigned to two weight-matched groups at the age of 12 weeks. OKG was administered orally to the experimental group ( N = 17) at the dose of 0.4 g/kg body weight per day, while the control group ( N = 16) received an equal dose of the vehicle. The turkeys were slaughtered at the age of 19 weeks and the tibiae were isolated for analysis. The effect of OKG on skeletal system development in turkeys was evaluated in relation to both geometrical and mechanical properties as well as quantitative computed tomography (QCT). Free amino acids concentrations were assessed with the use of ion-exchange chromatography. Significantly increased bone mineral density of the trabecular and the cortical bone of tibia in the turkeys given OKG for the last 7 weeks of production cycle were observed ( P < 0.05). OKG administration improved mechanical endurance of the tibia estimated by the three-point bending test ( P < 0.01). Plasma amino acid analyses showed increased level of aspartate, proline, alanine, valine, isoleucine, leucine, and ornithine (all P < 0.05) after OKG treatment, whereas cystathionine concentration was decreased ( P = 0.03). Obtained results indicate that oral OKG administration has beneficial effects on skeletal development in fast growing turkeys and this effect is connected with increased amino acid synthesis. These observations may serve to improve skeletal properties in birds, especially when considering that skeletal disorders often affect the tibia and the proper function of the skeletal system plays an essential role in animal welfare and poultry production.

Dietary compliance in ornithine aminotransferase deficiency

Ornithine delta-aminotransferase (OAT) deficiency (McKusick 258870) is associated with hyperornithinaemia, thought to be the cause of the progressive retinal degeneration that occurs in this disorder. For the large majority of cases unresponsive to the co-factor pyridoxine, treatment is based on reducing ornithine plasma levels below 400 micromol/L with an arginine-restricted diet. This has been shown to slow the progression of retinal disease. (Santinelli et al 2004). In Table 1 we present our experience in the dietary management of 12 patients (7 female) from 8 families. Compliance was defined as good, intermediate or poor according to plasma ornithine levels. Only one patient could be categorized as a good complier, 5 were intermediate, and 6 were poor. The age at start of treatment was the most important factor as regards ability to comply with diet. Our study emphasizes the difficulty with dietary treatment and need for early diagnosis. For the older patients, alternative treatments such as the use of oral lysine to increase renal losses of ornithine need to be investigated further (Peltola et al 2000).

Melatonin Reduces Nitric Oxide via Increasing Arginase in Rhabdomyolysis-Induced Acute Renal Failure in Rats

Melatonin, the chief secretory product of the pineal gland, is a direct free radical scavenger. In addition to a direct scavenging effect on nitric oxide (NO), its inhibitory effect on nitric oxide synthase (NOS) activity has been also reported. L-arginine is the substrate for both NOS and arginase. It has been suggested that there is a competition between arginase and NOS and that they control each other's level. NO plays a crucial role in the pathogenesis of myoglobinuric acute renal failure (ARF). In this study, the authors aimed to investigate the effect of melatonin on arginase activity, ornithine, and NO levels on the myoglobinuric ARF formed by intramuscular (im) injection of hypertonic glycerol. Forty rats were randomly divided into four groups. Rats in SHAM were given saline, and those in groups ARF, ARF-M5, and ARF-M10 were injected with glycerol (10 mL/kg) im. Concomitant and 24 hours after glycerol injection for the ARF-M5 and ARF-M10 groups, melatonin—5 mg/kg and 10 mg/kg, respectively—was administrated intraperitoneally. Forty-eight hours after the glycerol injection, kidneys of the rats were taken under anesthesia. Arginase activity, ornithine, and NO levels in the kidney tissue were determined. Melatonin had an increasing effect on kidney tissue arginase activities and ornithine levels while decreasing NO concentration. It is possible that besides the direct scavenging effect, the stimulatory effect of melatonin on arginase activity may result in an inhibition of NOS activity and, finally, a decrease in the kidney NO level.

Inhibition of Inducible Nitric Oxide Synthase Alters Thy-1 Glomeruonephritis in Rats

Background/Aims: Inducible nitric oxide (NO) synthase (iNOS) generated NO increases in the early phase of Thy-1 glomerulonephritis concurrently with mesangiolysis and reduction in glomerular filtration rate (GFR). Activation of ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, is upregulated to allow mesangial cell proliferation which constitutes the repair phase in this model. Antiproliferative high-output NO generation inhibits proproliferative ODC activity, thereby temporally separating the early ‘bactericidal’ phase from the later ‘growth’ repair phase. Methods: Renal function, ODC protein expression, arginine, ornithine, and polyamines by high-performance liquid chromatography, and histological changes were assessed in rats after induction of Thy-1 nephritis with and without NOS inhibition. Results: Thy-1 significantly reduced the GFR relative to untreated controls. Treatment with a nonspecific NOS inhibitor, but not a selective iNOS inhibitor, further decreased the GFR at day 1. This implys a protective role for constitutive NOS in the early phase of this inflammatory model. Selective iNOS inhibition abrogated increased plasma NO₂/NO₃ levels in Thy-1 glomerulonephritis, but did not significantly reduce mesangiolysis. However, inhibition of iNOS did result in significantly more nuclei/glomerulus during the proliferative phase, increasing the hypercellularity component of this disease model. This correlates with increased levels of polyamines, ornithine, and arginine beyond those observed with Thy-1 administration alone. Conclusions: These studies provide evidence that NO generation from different NOS isoforms can be protective in the temporal course of Thy-1 glomerulonephritis. The finding that iNOS attenuates hypercellularity in the repair phase of this inflammatory model adds cautionary insight in the therapeutic use of selective iNOS inhibition in vivo.

Dysregulated Arginine Metabolism and Elevated Arginase Activity in Thalassemia.

Pulmonary hypertension (PHT) is associated with high mortality rate and is a leading factor in heart failure and death in thalassemia (Thal) intermedia. However, data on PHT and Thal major is limited. While there are several risk factors for PHT in Thal major, ongoing chronic hemolysis, despite transfusion, supports the development of hemolysis-associated PHT. Recently, we reported in sickle cell disease a novel paradigm whereby hemolysis liberates vasoactive hemoglobin and erythrocyte arginase, resulting in impaired NO bioavailability, endothelial dysfunction, PHT and death. Since arginase activity is also elevated in Thal red cells, we hypothesize that elevated arginase contributes to dysregulated arginine (Arg) metabolism in Thal. Pilot data was analyzed from transfused Thal patients (8 Thal-major, 4 E-beta Thal, 2 Hb H alpha Thal). Echocardiogram were performed in steady state in 10 of the patients; 70% (7/10) demonstrated PHT (tricuspid regurgitant jet velocity ≥ 2.5 m/s). Plasma Arg trended lower in patients with Thal (19.5 to 122mM, median 50 mM) compared to controls. Ornithine (Orn) levels were higher, and Arg/Orn ratio was lower in Thal vs. contrls. Plasma arginase activity was significantly elevated (median 0.83 mmol/cc/hr, range 0.06 – 1.17). Proline, a downstream metabolite of arginase causing pulmonary vascular remodeling was also elevated. Exhaled nitric oxide (NO) levels are significantly elevated in Thal vs. controls (49±41 parts per billion vs.18±8 ppb, p=0.02), suggesting upregulation of NO synthase in the lungs in addition to higher plasma arginase activity. Recent findings indicate diverse origins of PHT share similar pathophysiologic abnormalities, particularly decreased Arg bioavailability and a shift of metabolism towards ornithine-dependent pathways. Hemolysis is most likely a trigger for these pathologic pathyways in hemoglobinopathies. Therapies that maximize Arg and NO bioavailability may benefit patients with thalassemia.VariableNL Control (n=36)Thalassemia (n=14)p*Arginine (μM)67±1857±26 (50)0.15Ornithine (μM)62±2285±680.05Arg/Orn ratio1.2±0.50.79±0.4<0.01Proline (μM)161±48258±116<0.001Citrulline (μM)25±1142±17<0.001Arginase (μmol/cc/hr)0.33±0.2 (n=45)0.71±0.3<0.001

Cystoid Macular Edema in Gyrate Atrophy of the Choroid and Retina: A Fluorescein Angiography and Optical Coherence Tomography Evaluation

To analyze the importance f optical coherence tomography (OCT) to diagnose the cystoid macular edema in a case of gyrate atrophy. Observational case report. A 12-year-old boy presenting with gyrate atrophy of the choroid and retina underwent ophthalmologic, clinical, and laboratory tests. Plasma ornithine level was 735 mumol/l. Fluorescein angiography showed bilateral hyperfluorescence involving the central region of the macula. Optical coherence tomography (OCT) disclosed bilateral intraretinal cysts areas of low reflectivity with occasional high-signal elements bridging the retinal layers and intraretinal thickening. Both fluorescein angiography and OCT were helpful to confirm the diagnosis of macular involvement as a complication of gyrate atrophy of the choroid and retina in a patient who presented without any clinical evidence of cystoid macular edema, except a decrease in visual acuity.

Arginase-Producing Myeloid Suppressor Cells in Renal Cell Carcinoma Patients: A Mechanism of Tumor Evasion

Myeloid suppressor cells with high arginase activity are found in tumors and spleen of mice with colon and lung cancer. These cells, described as macrophages or immature dendritic cells, deplete arginine and impair T cell proliferation and cytokine production. Although arginase activity has been described in cancer patients, it is thought to originate from tumor cells metabolizing arginine to ornithine needed to sustain rapid cell proliferation. The goal of this study was to determine whether myeloid suppressor cells producing high arginase existed in renal cell carcinoma patients. Peripheral blood mononuclear cells from 123 patients with metastatic renal cell carcinoma, prior to treatment, were found to have a significantly increased arginase activity. These patients had a markedly decreased cytokine production and expressed low levels of T cell receptor CD3zeta chain. Cell separation studies showed that the increased arginase activity was limited to a specific subset of CD11b+, CD14-, CD15+ cells with a polymorphonuclear granulocyte morphology and markers, instead of macrophages or dendritic cells described in mouse models. Furthermore, these patients had low levels of arginine and high levels of ornithine in plasma. Depletion of the CD11b+, CD14- myeloid suppressor cells reestablished T cell proliferation and CD3zeta chain expression. These results showed, for the first time, the existence of suppressor myeloid cells producing arginase in human cancer patients. In addition, it supports the concept that blocking arginase may be an important step in the success of immunotherapy.

Effects of glyphosate, chlorsulfuron, and methyl jasmonate on growth and alkaloid biosynthesis of jimsonweed ( Datura stramonium L.)

The troublesome agronomic weed, jimsonweed ( Datura stramonium L.), is also a major poisonous plant. The toxicity of jimsonweed is due to tropane alkaloids, which contain a methylated nitrogen atom ( N-CH 3) and include the anticholinergic drugs atropine, hyoscyamine, and scopolamine, as well as the narcotic cocaine. The enzyme and gene regulatory system of tropane alkaloid in plants is not clearly understood. The effects of the herbicides chlorsulfuron and glyphosate, and the growth regulator methyl jasmonate on the growth and alkaloid biosynthesis of jimsonweed were investigated. The growth responses of jimsonweed were characterized by determining the molar concentration of the herbicides required to inhibit plant root fresh weight by 50% ( I 50). Chlorsulfuron and glyphosate inhibited root growth of jimsonweed seedlings; the I 50 was 8 × 10 −9 and 10 −7 M, respectively. Methyl jasmonate increased root growth of jimsonweed seedlings at 10 −6 and 10 −7 M, but was inhibitory at 10 −5 M. Tropane alkaloids are produced by the condensation of tropine and tropic acid, a phenylalanine-derived intermediate. Phenylalanine levels in jimsonweed seedlings were reduced by glyphosate and chlorsulfuron. Methyl jasmonate at 10 −8 M or greater concentrations induced phenylalanine levels in jimsonweed seedlings. Arginine and ornithine levels in jimsonweed seedlings were increased two to three times by chlorsulfuron and glyphosate, but reduced by methyl jasmonate. Contents of tropinone, ϕ-tropine, and tropine in jimsonweed seedlings were reduced by chlorsulfuron and glyphosate, but increased by methyl jasmonate at 10 −7 and 10 −6 M. Putrescine N-methyltransferase (PMT) is the first committed enzyme, which drives the flow of nitrogen away from polyamine biosynthesis to tropane alkaloid biosynthesis. The expression of PMT mRNA transcripts was reduced in jimsonweed roots treated with 10 −6 M chlorsulfuron and glyphosate. PMT mRNA transcripts of jimsonweed roots were greatly induced following treatment with 10 −7 M methyl jasmonate. These results indicate that methyl jasmonate enhanced PMT activity due to an increase of PMT mRNA. The effects of glyphosate and chlorsulfuron on PMT mRNA’s transcriptional control and the accumulation of amino acid arginine/ornithine contents, coupled with their inhibitory effect on phenylalanine, tropinone, ϕ-tropine, and tropine levels, suggest that these herbicides might cause a decrease in overall tropane alkaloid biosynthesis in jimsonweed. However, the relationship between plant growth and metabolism affected by these compounds is not clear.

Δ1-pyrroline-5-carboxylate synthase deficiency: neurodegeneration, cataracts and connective tissue manifestations combined with hyperammonaemia and reduced ornithine, citrulline, arginine and proline

Delta1-pyrroline-5-carboxylate synthase (P5CS) catalyses the reduction of glutamate to Delta1-pyrroline-5-carboxylate, a critical step in the biosynthesis of proline, ornithine and arginine. Recently, we reported a newly recognised inborn error due to deficiency of P5CS in two sibs, one presenting at birth with hypotonia, dysmorphic signs, pes planus and clonic seizures. Both developed progressive neurodegeneration and peripheral neuropathy, joint laxity, skin hyperelasticity and bilateral subcapsular cataracts. Their metabolic phenotype includes mild hyperammonaemia, hypo-ornithinaemia, hypocitrullinaemia, hypo-argininaemia and hypoprolinaemia. Incorporation of 3H-proline into protein was deficient in fibroblasts incubated with 3H-glutamate. Both patients are homozygous for the missense mutation R84Q in P5CS. Here, we describe the clinical phenotype of the sibs in detail and show that a relative deficiency of urea cycle intermediates (ornithine, citrulline and arginine) during fasting periods results in a paradoxical hyperammonaemia. Furthermore, we show the results of ornithine loading tests and indirect enzyme studies corroborating the biological significance of the defect in P5CS in vivo. The metabolic phenotype of Delta1-pyrroline-5-carboxylate synthase deficiency is easily missed. The combination of low levels of ornithine, citrulline, arginine and proline plus a tendency to hyperammonaemia or one of the above together with a clinical phenotype of neurodegeneration with peripheral neuropathy and/or cataracts and connective tissue manifestations should suggest this disorder. Early recognition would allow a therapeutic trial with citrulline and proline.

Vitamin B6-Responsive Ornithine Aminotransferase Deficiency with a Novel Mutation G237D

Ornithine aminotransferase (OAT) deficiency (MIM: 258870) is a rare congenital metabolic disorder characterized by gyrate atrophy of the choroid and retina. Here, we report a 37-year-old male with gyrate atrophy of the choroid and retina who has been treated for 18 years. At the age of 7 years, the patient consulted an ophthalmologist due to progressive loss of vision. A large atrophied area was observed in his retina, and OAT deficiency was suspected. At the age of 19 years, amino acid analysis revealed high serum ornithine levels (1,140 nmol/ml), with the normal range being 40-100 nmol/ml. He was treated with vitamin B(6) 300 mg/day for 6 months, which successfully reduced his serum ornithine levels by 20-30%. For 18 years since, his serum ornithine levels have been maintained with vitamin B(6) medication. There was no further impairment of vision or increase in the atrophied area, as judged by ophthalmoscopic examination. OAT activity was undetected in white blood cells of the patient and was 105% and 45% of normal values in his wife and son, respectively. OAT gene analysis revealed a novel mutation of Gly237Asp in exon 7 (710G > A) in both alleles of the patient, while his son was a heterozygote for the mutation. Notably, this novel mutation is associated with a vitamin B6-responsive phenotype. Therefore, early diagnosis and treatment with vitamin B(6) may prevent loss of vision in some patients with OAT deficiency.