Kinetic analysis of a new human ornithine carbamoyltransferase variant.

A new human enzymatic variant was found in a patient with ornithine carbamoyltransferase (carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) deficiency. This mutant enzyme has decreased affinity, with an abnormal Km value for ornithine (3-5-times greater than control at all pH values). The maximal velocity (V) varied with pH as a normal enzyme but the sigmoid curve obtained (V vs. pH) is shifted towards alkaline pH values. The pK of the functional catalytic group is 8.3 instead of 6.65 of a control enzyme. At its optimum pH the V of the mutant enzyme is greater than the V of the normal enzyme. Other mutant enzyme proteins with abnormal affinity for ornithine have already been described. They all are different from the reported here.

2-Acetamidoglucal, a new metabolite isolated from the urine of a patient with sialuria.

A new metabolite, namely 2-acetamidoglucal, has been found in the urine of a patient with sialuria in addition to the metabolites N-acetylneuraminic acid, N-acetylmannosamine, N-acetylglucosamine and 2-deoxy-2,3-dehydro-N-acetylneuraminic acid reported earlier. the structure has been identified by mass spectrometry and 360 MHz proton nuclear magnetic resonance spectroscopy and verified by synthesis. All accumulated compounds fit into the metabolic pathway for the biosynthesis of CMP-N-acetylneuraminic acid. Sialuria is discussed in terms of a failure of regulation of UDP-N-acetylglucosamine 2-epimerase.

Structure of the three major sialyl-oligosaccharides excreted in the urine of five patients with three distinct inborn diseases: "I cell disease" and two new types of mucolipidosis.

The urine of five patients with three distinct diseases ("I Cell disease" and two new types of mucolipidosis) contains sialic acid-rich oligosaccharides in a high amount: 50- to 500-fold the normal. The structure of the major components are as follows: alphaAcNeu(2 leads to 6)betaGal(1 leads to 4)betaGlcNac(1 leads to 2)alphaMan(1 leads to 3)betaMan(1 leads to 4)GlcNac,[alphaAcNeu(2 leads to 6)]betaGal(1 leads to 4)betaGlcNAc(1 leads to 2)alphaMan(1 leads to 3)[betaGal(1 leads to 4)betaGlcNac(1 leads to 2)alphaMan(1 leads to 6)]betaMan(1 leads to 4)GlcNAc and alphaAcNeu(2 leads to 6)betaGal(1 leads to 4)betaGlcNAc(1 leads to 2)alphaMan(1 leads to 3)[alphaAcNeu(2 leads to 6)betaGal(1 leads to 4)betaGlcNAc(1 leads to 2)alphaMan(1 leads to 6)]betaMan(1 leads to 4)GlcNAc. These results suggest that a deficit in alpha-neuraminidase is associated to these three different disorders and that an endo-beta-D-N-acetylglucosaminidase is able to release sialyoligosaccharides by splitting the sialylglycans of glycoproteins.

Sex hormone-binding globulin in the diagnosis of peripheral tissue resistance to thyroid hormone: the value of changes after short term triiodothyronine administration.

Thyroid hormone is one of several factors that modulate the level of sex hormone-binding globulin (SHBG) in serum. SHBG levels are usually elevated in thyrotoxicosis and have been reported to be normal in a few patients with generalized resistance to thyroid hormone (GRTH). This study was designed to determine whether basal serum SHBG levels or the SHBG response to short term T3 administration could be used as an index of thyroid hormone action and thus serve as a test for the evaluation of patients suspected of having peripheral tissue resistance to thyroid hormone. Serum SHBG, total T4, free T4 index (FT4I), total T3, and TSH levels were measured in 21 normal subjects, 28 hypothyroid patients, 20 thyrotoxic patients, and 10 patients with GRTH. Excluding patients with GRTH, serum basal SHBG values were correlated with FT4I values (r = 0.66; P less than 0.0001). Mean SHBG levels in the patients with GRTH [37.6 +/- 16.2 (+/- SD) nmol/L] were not significantly different from those in the normal subjects (35.1 +/- 19.3 nmol/L) or hypothyroid patients (26.3 +/- 17.1 nmol/L), but were significantly lower than those in the thyrotoxic group (64.7 +/- 19.2 nmol/L; P less than 0.001). All 10 patients with GRTH had basal SHBG values in the normal range, but 7 of 20 (35%) thyrotoxic patients also had normal basal SHBG values. T3 was given orally for three sequential 3-day periods at doses of 50, 100, and 200 micrograms daily to 7 normal subjects, 11 hypothyroid and 3 thyrotoxic patients, and all 10 patients with GRTH. The serum SHBG concentration was measured on the last day at each dosage level. During T3 administration, SHBG levels increased in all individuals with normal tissue responsiveness. The increase above the basal value (delta SHBG) at each T3 dose was similar in normal, hypothyroid, and thyrotoxic individuals (non-resistant subjects). After administration of 50 micrograms T3 daily, the mean delta SHBG level was decreased [-2.9 +/- 5.3 (+/- SD) nmol/L] in the resistant patients and increased (4.0 +/- 4.9 nmol/L; P less than 0.005) in the nonresistant subjects. After administration of 100 micrograms T3 daily, the mean delta SHBG was -4.5 +/- 6.8 nmol/L in the resistant patients and 8.6 +/- 5.1 nmol/L (P less than 0.0001) in the nonresistant subjects. Serum SHBG decreased by more than 2 nmol/L in 6 of 10 (60%) resistant patients, but in no nonresistant subject.(ABSTRACT TRUNCATED AT 400 WORDS)

Nutritional status of children with acute lymphoblastic leukemia: a longitudinal study.

To evaluate the nutritional consequences of acute lymphoblastic leukemia and its treatment, 15 children with leukemia were studied. Anthropometric data, fat-free mass by impedance, energy intake, and resting energy expenditure (REE) were determined at diagnosis and on days 22, 36, and 71 of the treatment. Interleukin (IL)-1 beta, IL-6, interferon-gamma, and tumor necrosis factor were also measured. Fifteen healthy control subjects were matched for age and sex. Body weight and height and body composition were comparable at all times of the study, although three children were underweight at diagnosis (weight-for-height < 85% of French standards). Although two different methods were used for dietary recall in the two groups, energy intake expressed as a percentage of normal recommended values for age and sex was lower in patients than in control subjects (104 +/- 19%) on day 1 (47 +/- 32.1%) and day 22 (58 +/- 24%), but was comparable on day 36 (85 +/- 71%) and day 71 (85 +/- 48%). This low energy intake involved both carbohydrates and fats. Energy and carbohydrate intakes improved significantly during the study in patients. The nonprotein respiratory quotient (RQ) in patients was significantly lower than in control subjects (0.84 +/- 0.04) on day 1 (0.79 +/- 0.02) but was comparable on day 71. The REE of the patients on day 1 (5057.8 +/- 1588.4 kJ/24 h) and day 71 (4844.7 +/- 116.1 kJ/24 h) and of the control subjects (4313.8 +/- 823.5 kJ/24 h) was not significantly different. Cytokines remained undetectable on days 1, 36, and 71. The results showed that at the time of diagnosis and during this period of chemotherapy there was no evidence of raised REE. The poor intakes during the first month of chemotherapy were recent as shown by the parents' questionnaire responses and the absence of consequences in body composition. The transient decrease in RQ seemed to be an adaptative mechanism to the poor carbohydrate intake. No indication of undernutrition in the patients as a group was evident during the first 71 d of treatment although further long-term nutritional assessment is needed.

Developmental aspect of phenylalanine hydroxylase in the rat -- hormonal influences.

Interpretations of the development of phenylalanine hydroxylase (PAH) in rat liver have been controversial, and the mechanism of ontogenic changes have not yet been elucidated. Fetal PAH activity at a gestational age of 21 days appeared to reach 32% that of adult male level at birth. The in vivo effectiveness of fetal PAH activity was correlated with enhancement of blood tyrosine, while amino-transferase activity appeared only after birth. No sex difference was noted in weaning rats, whereas, in adult females, PAH activity was only 42% that of males. Investigating hormonal influences on liver PAH activity we noted no change of enzyme activity following hydrocortisone, ACTH and estradiol treatment. However, 4 days of testosterone treatment in weaning female rats increased PAH activity (X1.7). Therefore, testosterone could explain increased PAH activity in adult males.

Phenylalanine analogues as inhibitors of phenylalanine-hydroxylase from rat liver. New conclusions concerning kinetic behaviors of the enzyme.

The conversion of phenylalanine to tyrosine is catalysed by phenylalanine-hydroxylase. The substrate phenylalanine shows two effects: (1) allosteric transition at low phenylalanine concentrations, (2) excess substration inhibition. The molecular structure of phenylalanine-hydroxylase has not yet been elucidated. However, a tetrameric structure has been proposed. The Kinetic analysis with respect to substrate analogues suggest the existence of three types of sites on each protomer: (1) a catalytic site, (2) a non-competitive inhibitory site, (3) a positive cooperative site. Use of the enzyme's natural cofactor, tetrahydrobiopterin, has been emphasized to ensure good interpretation of the kinetic results of the phenylalanine-hydroxylase effectors.

A new experimental model of hyperphenylalaninemia in rat. Effect of p-chlorophenylalanine and cotrimoxazole.

A new experimental model of hyperphenylalaninemia was proposed. Combination of p.chlorophenylalanine, strongly inhibitor of phenylalanine hydroxylase, and cotrimoxazole, presumably inhibitor of dihydropteridine reductase, produced a good inhibition of phenylalanine hydroxylation in vivo. Thus phenylalaninemia reached values similar to those found in PKU patients, without administration of excess phenylalanine. Tyrosine concentrations remained near the control values and a phenylketonuria occurred.

[Chemistry of urinary mannosides excreted in mannosidosis]. / Etude chimique des 'mannosides urinaires excrétés au cours de la mannosidose

Mannose-rich oligosaccharides have been isolated from urines of 5 patients with mannosidosis. Their compositon and structure were determined. Three of them have been previously described by Norden et al: alpha p-Manp-(1 leads to 3) beta-d-Manp-(1 leads to 4) d-GlcNAcp; alpha-p-Manp-(1 leads to 2), alpha-d-Manp-(1 leads to 3) beta-d-Manp-(1 leads to 4) d-GlcNAc and alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 3) beta-d-Manp-(1 leads to 4) d-GlcNAcp, but the four others are new entities: alpha-d-Manp-(1 leads to 3) (alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 6) beta-d-Manp-(1 leads to 4) GlcNAcp; alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 3) (alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 6) beta-d-Manp-(1 leads to 4) GlcNAcp; alpha-d-Manp-(1 leads to 2), alpha-d-Man-(1 leads to 3) (alpha-d-Manp-(1 leads to 6) beta-d-Manp-(1 leads to 4) GlcNAp and alpha-d-Manp-(1 leads to 2) alpha-d-Manp-(1 leads to 3) (alpha-d-Manp-(1 leads to 6) beta-d-Manp-(1 leads to 4) GlcNAcp. These structures are related to the glycans of "oligomannosidic type" present in numerous glycoproteins. All possess a N-acetylglucosamine residue in terminal reducing position and reinforce the hypothesis of Kobata et al. and Montreuil et al. that catabolism of glycans N-glucosidically linked to the protein moiety begins by the aciton of a beta-endo-N-acetylglucosaminidase.

Lipoprotein pattern and plasma lecithin cholesterol acyl transferase activity in children with Alagille syndrome.

Alagille syndrome is frequently associated with hyperlipidemia and xanthoma. The aim of the study was to assess the lipid profile (plasma lipoproteins, apolipoproteins (apo)) and lecithin cholesterol acyl transferase (LCAT) activity, with and without treatment with cholestyramine in Alagille syndrome. Five children (mean age = 6 +/- 4 years) with Alagille syndrome were studied at two different times while receiving no treatment, and while receiving cholestyramine. They were compared with 12 normal controls, who were not different from patients for age and sex. In Alagille syndrome, total serum cholesterol, triglycerides and phospholipids were elevated compared with the controls (P < 0.008). VLDL-cholesterol, LDL-cholesterol, HDL-triglycerides, LDL-triglycerides and VLDL-phospholipids were higher, whereas HDL-cholesterol was lower than controls (P < 0.03). Apo B, CIII, E and lipoprotein particles Lp AI were higher (P < 0.001), whereas Lp AI:AII was lower than controls (P < 0.03). Lipoprotein-X was present in the 5 children with Alagille syndrome and explained in part the elevation of plasma cholesterol, phospholipids, and apo CIII. LCAT activity was decreased (P < 0.01) and might cause some abnormalities of HDL with lower cholesterol, higher triglycerides, apo E and apo CIII contents than controls, and abnormalities of VLDL and LDL with higher cholesterol, triglycerides, phospholipids and apo B contents than controls. Some of the risk factors of atherosclerosis were found in Alagille syndrome, namely high levels of plasma cholesterol, LDL cholesterol, apo B, apo B/apo AI. Treatment with cholestyramine resulted in a few modifications to the lipid profile, while lipoprotein-X and the decrease of LCAT activity persisted.

Lipoprotein Lp(a) in homozygous familial hypercholesterolemia: density profile, particle heterogeneity and apolipoprotein(a) phenotype.

Homozygous familial hypercholesterolemia (FH) is a genetic disorder featuring a functional defect in cellular LDL receptors, marked elevation in circulating LDL concentrations, and premature atherosclerosis. The potential atherogenic role of apo B-containing lipoproteins other than LDL in this disease is indeterminate. We describe the quantitative and qualitative characteristics of Lp(a) as a function of apo(a) phenotype in a group of eight, unrelated homozygous FH patients. Plasma Lp(a) levels were significantly elevated (2.5-fold; mean 50 +/- 32 mg/dl) as compared to those in healthy subjects. The S2 isoform of apo(a) occurred most frequently (6 of eight patients); the rare B isoform presented in three patients. Plasma Lp(a) levels in homozygous FH did not correspond to those predicted by apo(a) phenotype. Analyses of the density distribution of Lp(a) and of Lp(a) particle size and heterogeneity as a function of density did not reveal any anomalies characteristic of homozygous FH. However, comparison of the hydrated density of Lp(a) particles as a function of apo(a) isoform content revealed a clear influence of isoform on this parameter; thus, in a B/S2 heterozygous patient, the density distribution of Lp(a) fractions containing isoform B alone, B and S2, and S2 alone, demonstrated that the apparent molecular weight of apo(a) plays a determining role in controlling the hydrated density and size of the resulting Lp(a) particle. Indeed, patients expressing the high molecular weight, S2 isoform uniformly displayed a dense form of Lp(a) (hydrated density approximately 1.055 g/ml). In subjects presenting two apo(a) isoforms, each isoform resided on distinct lipoprotein particles; in such cases, the plasma levels of the denser isoform predominated, suggesting differences in rates of formation, or rates of tissular catabolism, or in the plasma stability of the particles, or a combination of these mechanisms. Considered together, our data may be interpreted to suggest that the elevated circulating levels of Lp(a) in homozygous FH patients may reflect either an increased biosynthesis, or diminished catabolism via the cellular LDL receptor pathway, or a combination of both.

Percutaneous endoscopic gastrostomy in children: influence on gastroesophageal reflux.

OBJECTIVE: Few data exist in the literature about the relationship between percutaneous endoscopic gastrostomy (PEG) and gastroesophageal reflux (GER) in children, and the data that do exist are contradictory. The aim of the present study was to evaluate the effect of PEG on GER. METHODS: Twenty children underwent PEG for enteral nutrition. They were 55 +/- 55 months old and weighed 13 +/- 10 kg. A pH study was performed before and after PEG without treatment when GER status was unknown (n = 10) or under treatment (n = 10) if previous GER was demonstrated. In these cases, the pH study was performed under the same treatment before and after PEG. RESULTS: Six pH studies had abnormal results before PEG. After PEG, the GER of these 6 children significantly improved after the treatment was intensified (n = 50 or spontaneously normalized (n = 1). Results of 13 pH studies that were previously normal remained normal. Only one child with a normal reflux index before PEG had GER after it. For the 20 children, the mean reflux index did not change significantly after PEG (5.5% vs 5.6%). CONCLUSION: Contrary to surgical gastrostomy, PEG does not worsen GER. Therefore, GER is not a contraindication to PEG.

Omodysplasia.

Three cases of a new congenital bone disorder associating facial anomalies (depressed nasal bridge, broad base of the nose, long philtrum) with short humeri. The complex skeletal abnormalities consist of a defect of growth of the distal end of the humerus, a hypoplastic everted condyle, an upper radioulnar diastasis, and a anterolateral dislocation of the head of the radius. The condition is dominantly inherited. Two other cases with the same facial anomalies and osteoarticular abnormalities of the upper limbs are described. These cases also showed a severe micromelic dwarfism due to shortness of the long bones, particularly the femora. The present authors consider that these represent variable expressivity of the same disorder and propose that this condition be called omodysplasia (from the Greek term for humerus).

The GAPO syndrome.

A new case of GAPO syndrome is described in a 4-year-old Algerian girl born of first-cousin parents. This patient also had a right pyelic kidney stone and cerebral venous circulation anomalies inducing scalp vein expansion.

Familial hyperinsulinism with nesidioblastosis of the pancreas: further evidence for autosomal recessive inheritance.

We report on a brother and sister with hyperinsulinism and nesidioblastosis of the pancreas. In addition, one brother and one sister who died in the neonatal period were probably affected. The parents of these children were healthy and consanguineous. We think that this is strongly suggestive of autosomal recessive inheritance. Seven other reports of presumed autosomal recessive hyperinsulinism are reviewed. To our knowledge, we report the first case in sibs whose parents were consanguineous. We think that early recognition of the condition is of obvious importance not only for therapy, but also for purposes of genetic counseling.

Brachmann-de Lange syndrome: pre- and postnatal findings.

Brachmann-de Lange syndrome (BDLS) is a well-delineated and relatively common syndrome. However, prenatal diagnosis has never been reported, even if in some cases ultrasonography demonstrated one or more manifestations of the syndrome. We report on 3 cases: in the first 2 cases, prenatal ultrasonography demonstrated some signs of the condition. The third represents, to our knowledge, the first prenatal diagnosis of BDLS. We also present a review of the literature concerning pre- and postnatal findings in this syndrome.

Blau syndrome of granulomatous arthritis, iritis, and skin rash: a new family and review of the literature.

Blau syndrome (MK186580) comprises granulomatous arthritis, iritis, and skin rash, and is an autosomal-dominant trait with variable expressivity. So far it was described in 5 families. We report on a sixth family with severe progression of eye involvement and discuss the nosology with similar diseases, such as early-infantile sarcoidosis.

Ocular findings in I-cell disease (mucolipidosis type II).

The ultrastructural study of the eyes in seven patients affected with I-cell disease (mucolipidosis type II) revealed important changes in the corneal, scleral, and uveal fibroblasts, while other cells were rarely involved. This explains the inconstant corneal clouding and the absence of ophthalmoscopic abnormalities clinically. At any moment of a patient's life, conjunctival biopsy specimens show characteristic alterations and allow the rapid and secure diagnosis of I-cell disease. This examination should be widely used in the screening of lysosomal diseases.

Unconjugated pteridines in human milk.

Defective de novo synthesis of tetrahydrobiopterin (BH4) has been reported as being responsible for neonatal hyperphenylalaninemia. The presence of BH4 and its derivatives in human milk is confirmed but the vitamin-like effectiveness of the BH4 supplied by human milk appeared doubtful.

Developmental aspects of pteridine metabolism and relationships with phenylalanine metabolism.

Large variations of pteridine elimination occur in childhood, due to the ontogenic development of the metabolism of tetrahydrobiopterin. The main feature is the slow maturation of biopterin synthesis whereas neopterin synthesis is high at birth; thus a high neopterin to biopterin ratio (4.4 +/- 2.1) occurs in the neonatal period, a ratio which then decreases to adult values (0.5 +/- 0.2). Comparing pteridine elimination of PKU patients with that of controls of the same age, a high excretion of biopterin and, to a lesser extent, of neopterin is found. In normal subjects, following an oral phenylalanine load, biopterin levels in urine and serum also increase, whereas variations of neopterin concentration are small. In rats, phenylalanine also leads to an increase of serum biopterin whereas liver biopterin decreases. This suggests that the main explanation for the biopterin increase in serum and in urine by phenylalanine is a release of the intracellular biopterin by the aminoacid.