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Diagnosis of intestinal transplant rejection depends on clinical assessment, endoscopy and most importantly, histology of intestinal biopsies. Plasma citrulline levels (P-Cit) reflect functional enterocyte mass in nontransplant patients and have been evaluated in two small series after transplant. This study was designed to determine the sensitivity and specificity of P-Cit as diagnostic tool for allograft injury, especially to distinguish between viral enteritis and rejection. We prospectively collected 403 P-Cit samples within 24 h of intestinal biopsy in 49 patients. P-Cit levels were correlated with the mucosal damage and histopathological diagnoses. P-Cit levels in bowels with significant mucosal damage (i.e. moderate or severe rejection, viral enteritis, PTLD, ischemia reperfusion injury, allergic enteritis) were significantly lower than in intestines with no or mild injury (i.e. indeterminate or mild rejection, nonspecific enteritis): 22.9 +/- 15.4 versus 38 +/- 23.2 nmol/mL (p < 0.0001). Sensitivity and specificity of the test were 80% and 58.1% for rejection, and 56.5% and 66% for viral enteritis, thereby unable to distinguish between both entities. In conclusion, P-Cit reflects the extent of mucosal injury regardless of the etiology, but does not seem to be a predictive marker for rejection or viral enteritis, as its values may decline only when diffuse mucosal damage has occurred.

Classic phenylketonuria (PKU) is characterized by severe mental retardation in untreated individuals and mild neurocognitive abnormalities in some early treated adults. The exact biochemical mechanisms underlying this neurotoxicity remain undetermined. Several theories implicate abnormal cerebral energy utilization and alterations in biochemical pathways that involve glucose metabolism. This pilot study was undertaken to investigate whether 18F-deoxyglucose positron emission tomography (PET) is an effective tool to study cerebral glucose metabolism in early treated PKU. After PET coregistration with SPGR MRI, relative glucose metabolic rates (rGMR) at the center of standard atlas positions was determined. Repeated measures MANOVA was used to assess regional metabolic differences, which were then correlated with age-specific and day-of-scan plasma phenylalanine and age. Patients with PKU in comparison to controls had decreased rGMR in cortical regions including the prefrontal, somatosensory, and visual cortices, and increased activity in subcortical regions including the striatum and limbic system. Day-of-scan phenylalanine correlated with abnormal activity in subcortical structures, and older age was associated with decreased activity in the prefrontal and visual cortices. The clinical significance of these abnormalities of glucose metabolism in specific areas of the brain remains unknown.

MR imaging features of mitochondrial encephalomyopathies, lactic acidosis, and stroke-like episodes, Kearns-Sayre/Pearson syndrome have been described in the literature. We describe extensive white matter changes with abnormal signal intensity lesions involving the deep gray nuclei and myelinated white matter tracts in an 18-year-old female with a large-scale 7.4 kb mitochondrial DNA deletion and a atypical presentation of Kearns-Sayre syndrome. Restricted diffusion due to status spongiosus at the involved sites is also discussed.

Maple syrup urine disease (MSUD) is a rare, autosomal recessive disorder of branched-chain amino acid metabolism. We noted that a large proportion (10 of 34) of families with MSUD that were followed in our clinic were of Ashkenazi Jewish (AJ) descent, leading us to search for a common mutation within this group. On the basis of genotyping data suggestive of a conserved haplotype at tightly linked markers on chromosome 6q14, the BCKDHB gene encoding the E1beta subunit was sequenced. Three novel mutations were identified in seven unrelated AJ patients with MSUD. The locations of the affected residues in the crystal structure of the E1beta subunit suggested possible mechanisms for the deleterious effects of these mutations. Large-scale population screening of AJ individuals for R183P, the mutation present in six of seven patients, revealed that the carrier frequency of the mutant allele was approximately 1/113; the patient not carrying R183P had a previously described homozygous mutation in the gene encoding the E2 subunit. These findings suggested that a limited number of mutations might underlie MSUD in the AJ population, potentially facilitating prenatal diagnosis and carrier detection of MSUD in this group.

Maple syrup urine disease (MSUD) is a metabolic disorder associated with often-fatal ketoacidosis, neurological derangement, and mental retardation. In this study, we identify and characterize two novel type IB MSUD mutations in Israeli patients, which affect the E1beta subunit in the decarboxylase (E1) component of the branched-chain alpha-ketoacid dehydrogenase complex. The recombinant mutant E1 carrying the prevalent S289L-beta (TCG --> TTG) mutation in the Druze kindred exists as a stable inactive alphabeta heterodimer. Based on the human E1 structure, the S289L-beta mutation disrupts the interactions between Ser-289-beta and Glu-290-beta', and between Arg-309-beta and Glu-290-beta', which are essential for native alpha(2)beta(2) heterotetrameric assembly. The R133P-beta (CGG --> CCG) mutation, on the other hand, is inefficiently expressed in Escherichia coli as heterotetramers in a temperature-dependent manner. The R133P-beta mutant E1 exhibits significant residual activity but is markedly less stable than the wild-type, as measured by thermal inactivation and free energy change of denaturation. The R133P-beta substitution abrogates the coordination of Arg-133-beta to Ala-95-beta, Glu-96-beta, and Ile-97-beta, which is important for strand-strand interactions and K(+) ion binding in the beta subunit. These findings provide new insights into folding and assembly of human E1 and will facilitate DNA-based diagnosis for MSUD in the Israeli population.

Two children, one with phenylketonuria (PKU) and the other nonphenylketonuric, from untreated pregnancies in a mother with PKU provided the opportunity to compare the degree of damage from maternal PKU between these genotypically different fetuses. Both the phenylketonuric offspring and her nonphenylketonuric sib were microcephalic at birth and had congenital anomalies, esophageal atresia in the former and congenital dislocation of the hip in the latter. However, the phenylketonuric child also had intrauterine growth retardation while the nonphenylketonuric sib had normal weight and length at birth. Both children are mentally retarded with an IQ below 50 in the phenylketonuric child despite early dietary treatment for PKU and an IQ of 54 in the nonphenylketonuric sib. Both children also have hypoplasia of the corpus callosum and enlarged cerebral ventricles. This experience and review of the literature indicates that the residual liver phenylalanine hydroxylase activity of a nonphenylketonuric fetus offers little or no protection from damage in untreated maternal PKU. Consequently, the outcome in maternal PKU is likely to depend on control of the maternal biochemical abnormalities in the mother regardless of whether the fetus has or does not have PKU.

We performed molecular, enzyme, and metabolic studies in 50 patients with D-2-hydroxyglutaric aciduria (D-2-HGA) who accumulated D-2-hydroxyglutarate (D-2-HG) in physiological fluids. Presumed pathogenic mutations were detected in 24 of 50 patients in the D-2-hydroxyglutarate dehydrogenase (D2HGDH) gene, which encodes D-2-hydroxyglutarate dehydrogenase (D-2-HGDH). Enzyme assay of D-2-HGDH confirmed that all patients with mutations had impaired enzyme activity, whereas patients with D-2-HGA whose enzyme activity was normal did not have mutations. Significantly lower D-2-HG concentrations in body fluids were observed in mutation-positive D-2-HGA patients than in mutation-negative patients. These results imply that multiple genetic loci may be associated with hyperexcretion of D-2-HG. Accordingly, we suggest a new classification: D-2-HGA Type I associates with D-2-HGDH deficiency, whereas idiopathic D-2-HGA manifests with normal D-2-HGDH activity and higher D-2-HG levels in body fluids compared with Type I patients. It remains possible that several classifications for idiopathic D-2-HGA patients with diverse genetic loci will be revealed in future studies.

Over 27 cases of liver transplant, kidney transplant and combined liver–kidney transplant have been reported for the treatment of methylmalonic aciduria. We describe a case of a 5-year-old boy who underwent combined liver–kidney transplant (CLKT) for phenotypic mut0 disease. His history was notable for more than 30 hospitalizations for severe acidosis, metabolic strokes, liver disease, pancreatic disease, chronic renal insufficiency with interstitial nephritis, and decreased quality of life. Post-CLKT, there was a marked reduction in serum (80%) and urine MMA levels (90%) as well as a cessation of metabolic decompensations. Neurologic deterioration continued post-CKLT manifested as a cerebellar stroke. The clinical details and therapeutic implications of solid organ transplant for methylmalonic aciduria are discussed.

* Abbreviation: SCOT = : succinyl-CoA:3-ketoacid CoA-transferase Succinyl-CoA:3-ketoacid CoA-transferase (SCOT) deficiency is, apparently, a rare disorder. Only nine patients have been reported since it was first described in 1972. The patients have various ethnic backgrounds: northern European,1-4African-American,5 Japanese,6 and African.7 This communication is to report a tenth patient from another far eastern country, Pakistan, and to suggest that this disease may not be very rare but rather is underdiagnosed. This infant's difficulties began in the newborn period. The pregnancy had been uneventful; the birth weight was 7 lb, 8 oz. He was readmitted to the hospital at 38 hours of age with a history of breathing difficulties since birth. He was lethargic and hypothermic; arterial blood gas determination revealed a pH of 7.16; the bicarbonate was 9.3, and there was a base deficit of −17.4. After correction of his acidosis he was started on a normal infant formula but became acidotic again. He was then given a low protein formula and did well for the next 9 months when he had an episode of acidosis precipitated by an upper respiratory tract infection. During the following 6 months he had a number of attacks of acidosis, each after an intercurrent infection. He was admitted to our Medical Center at 15 months of age. His weight was between the 10th and 25th percentiles, his length was on the 25th percentile and his head circumference was on the 10th percentile. His physical examination was unremarkable and a developmental assessment revealed normal development. His family history was significant in that his parents are first cousins and that there were other instances of family intermarriage. The exact nature was not known. Standard methods were used to determine plasma lactate, pyruvate, 3-OH …

Biopsy is the only means to identify intestinal graft rejection. Plasma citrulline (P-Cit) has been proposed as a marker for rejection after intestinal transplant (IT), but normative data is lacking. We analyzed P-Cit in IT recipients without rejection or other histological abnormalities. In 40 patients, P-Cit was measured with a Beckman amino acid analyzer within 24 h of protocol or clinically indicated endoscopic biopsy procured6 and360 days post-IT. Measurements included for analysis corresponded to normal (or minimally abnormal) biopsies that remained so for 7 days. These criteria were met by 145 samples from 10 adults and 14 children. Overall mean P-Cit (nmol/mL) was 34.0 +/- 19.9. Mean P-Cit was 22.2 +/- 13.2 between 6 and 30 days post-IT, 34.9 +/- 17.2 (p = 0.001) between 30 and 60 days, 43.6 +/- 15.8 between 60 and 90 days (p = 0.001), then stable until the end of the first year. Plasma citrulline was lower in 13 patients with body surface area (BSA)or = 1 m2 vs. 11 patients with BSAor = 1.1 m2 (p = 0.0001). Plasma citrulline increased linearly during the first 120 days in both BSA groups (r = 0.573 and r = 0.512; p = 0.0001). Within 3 months after IT, variations in P-Cit based on body size and postop interval should be considered when evaluating the need for histological confirmation of graft dysfunction.

The etiology of the tall stature almost invariably seen in homocystinuric patients is not known. The effect of metabolic control and the role of the GH-IGF system on growth were investigated in 10 patients with homocystinuria. There was a direct correlation between the plasma free homocyst(e)ine and growth velocity SD scores in 18 patient years (r, 0.46;p < 0.05). Plasma 2-y cumulative free homocyst(e)ine and height SD scores were directly correlated (r, 0.82;p < 0.01). Growth velocity SD scores were lower in patients with optimal metabolic control than in those with poorer control (−0.10 ± 0.65 versus 0.95 ± 0.68, p < 0.01). Height SD scores were also lower in the optimally controlled group (−0.01 ± 0.81 versus 1.73 ± 0.88, p < 0.05). GH and GH-related peptides did not deviate significantly from the reference ranges. These findings suggest that overgrowth is directly mediated by homocysteine, that the GH-IGF axis is not involved, and that it may be prevented by optimal metabolic control.

Publisher Summary This chapter identifies the major hereditary metabolic disease (HMD) categories in which seizures occur and classifies them according to the age at which clinical manifestations first are noted. Hereditary metabolic disorders (HMDs) represent only a small fraction of the epileptic syndromes of childhood. In a child with seizures, suspicion of an HMD is based on a detailed history of the disease including signs of developmental delay, progression, psychomotor regression, and, of major importance, the family history. Two early infantile disorders that constantly lead to intractable seizures are Alpers syndrome and glucose transporter protein deficiency. Glucose transporter protein deficiency starts in infancy with severe seizures, later followed by psychomotor retardation. Polymyoclonia represents a cardinal neurologic sign of several hereditary disorders, some of which are metabolic in origin. Lafora disease is a rapidly progressive autosomal recessive disease starting between 9 and 20 years with an average course of 4 years. It is found that In Unverricht–Lundborg disease, seizures may be relatively rare and intelligence little or unaffected, but polymyoclonus is gravely incapacitating.

9. Martin L, Ryckman F, Sheldon C. Experience with 95% pancreatectomy and splenic salvage for neonatal nesidioblastosis. Ann Surg 1984;200:355-62. 10. Wilson D, Carson D, Quinn R. Long-term use of somatostatin analogue SMS 201-995 in the treatment of hypoglycemia due to nesidioblastosis. Acta Paediatr Scand 1988;77:467-70. 11. Jackson JA, Hahn HB, Oltorf CE, O'Dorisio TM, Vinik AI. Long-term treatment of refractory neonatal hypoglycemia with long-acting somatostatin analog. J PEDIATR 1987;111: 548-51. 12. Jackson JA, Hahn HB, Oltorf CE. Long-acting somatostatin analog in refractory neonatal hypoglycemia: follow-up information [Letter]. J PEDIATR 1988;113:1118.

It is becoming increasingly apparent that pyridoxine responsive homocystinuria patients are being missed by newborn screening programs. The possibility that screening for homocystine, rather than the methionine, might be more effective was investigated by comparing homocystine and methionine levels of non-responsive patients at diagnosis. The plasma methionine levels of 11 infants were much more abnormal than the homocystine levels. Urine homocystine was low or not detectable and always less than methionine. Therefore, methionine determination is much more effective than homocystine determination for newborn screening for homocystinuria. It seems that a second blood specimen at a later age may be required to find the pyridoxine responsive infants.

Argininemia is an autosomal recessive disorder caused by a deficiency in the liver-type arginase enzyme. Clinical manifestations include progressive spastic diplegia and mental retardation. While the quality of life can severely deteriorate in most such patients, some do show remarkable improvement in neurological symptoms while on controlled diets. We examined the thesis that differences in clinical responses to dietary treatment are based on molecular heterogeneity in mutant arginase alleles. Genomic DNAs from 11 patients with argininemia were examined using the polymerase chain reaction, cloning, and sequencing. Nine mutations representing 21/22 mutant alleles were identified in 11 patients with argininemia, and four of these mutations were expressed in vitro to determine the severity of enzymatic defects. We found that these mutations accounted for 64% of the mutant alleles in our patients. Based on findings in vitro expression tests, the mutations can be considered either severe or moderate. Patients with at least one moderate mutant allele responded well to dietary treatment; concentrations of plasma arginine were controlled within 300 microM. In contrast, patients with two severely mutated alleles did not respond to dietary treatment and plasma arginine was over 400 microM. Argininemia is heterogeneous at the molecular level. The degree of clinical improvement during dietary treatment is reflected in the concentration of arginine in plasma, as a measure of metabolic control. Plasma arginine levels during treatment is reflected in the concentration of arginine in plasma, as a measure of metabolic control. Plasma arginine levels during treatment correlated with types of molecular defects in the arginase genes.

A patient with homocystinuria due to cystathionine β-synthase deficiency developed severe progressive polymyoclonus and ataxia. To our knowledge, this is the first time polymyoclonus and ataxia have been reported in association with homocystinuria. Although cerebrovascular thrombosis is usually thought to be responsible for neurologic dysfunction in homocystinuric patients, no infarctions were demonstrated on magnetic resonance imaging scans in our case. We have previously reported that baclofen dramatically improved the polymyoclonus and ataxia in a patient with Unverricht-Lundborg disease. Baclofen given to our patient reversed the polymyoclonus and the ataxia as well. This suggests that patients with polymyoclonus and ataxia, no matter what the etiology, may benefit from the use of baclofen. (J Child Neurol 1995; 10:294-296).

Classical Maple Syrup Urine Disease (MSUD) is a disease of infancy which is an inherited disorder of metabolism of branched-chain amino acids (BCAA). The BCAA are normally transaminated to branched-chain keto acids (BCKA). However, the enzyme required to metabolize the BCKA is deficient, resulting in elevation of both, the BCAA and the BCKA. One of the BCAA (isoleucine) produces a metabolite that causes the urine to smell like maple syrup. The elevations of the BCAA and BCKA are associated with an acute, critical neurotoxic condition often prior to the age of two weeks. The clinical state, the electroencephalogram-(EEG), and plasma BCAA levels were evaluated in 26 patients with classical and variant MSUD. Patients were seen from the time of diagnosis, often within a week after birth, and some were followed clinically for more than 20 years while on specific diet therapy. They were monitored by plasma BCAA (leucine, isoleucine and valine) levels and a total of 101 EEGs were performed during different phases of their illness. During periods of acute metabolic decompensation, there were marked clinical symptoms of neurotoxicity including opisthotonos, seizures, and coma with elevated BCAA plasma levels. The EEGs revealed spikes, polyspikes, spike-wave complexes, triphasic waves, severe slowing and bursts of periodic suppression. Occasionally paradoxical EEG arousal was noted while the patient was lethargic. During asymptomatic periods when the plasma BCAA were at low or normal levels, EEG abnormalities occurred in patients with and without residual neurological deficit. These observations included rolandic sharp waves (comb-like rhythm) which were observed in 7 of 15 patients less than two months of age. Additionally, paroxysmal spike and spike-wave response to photic stimuli were observed in 9 of 17 patients. Loading tests were performed on three patients. Clinical and EEG changes were most marked after leucine. Less dramatic EEG changes also occurred with the other two BCAA loads but without clinical manifestations. Elevation of the appropriate BCAA plasma level occurred after each load. These studies and a review of the literature suggest that one component of the pathophysiological mechanism for the acute neurotoxic effects in this disorder is related to a defect in glutamate, glutamine and gamma-aminobutyric acid (GABA) production. The BCAAs are transaminated to BCKAs. Further metabolism of the BCKAs are blocked because of enzyme deficiency required for decarboxylation.(ABSTRACT TRUNCATED AT 400 WORDS)

The determination of specific nutrients is important in the diagnosis of several inborn errors of metabolism. Phenylketonuria (PKU) is a well-known example. In this case, the nutrient, phenylalanine, is assayed to confirm a diagnosis and is routinely measured to monitor therapy, which consists of a diet low in this particular amino acid. Although many of the described inborn errors of metabolism are uncommon, or even rare, in occurrence, the laboratory plays an essential role in the diagnosis and management of these diseases.

A defect in intracellular uptake of carnitine has been identified in patients with severe carnitine deficiency. To define the clinical manifestations of this disorder, the presenting features of 15 affected infants and children were examined. Progressive cardiomyopathy, with or without chronic muscle weakness, was the most common presentation (median age of onset, 3 years). Other patients presented with episodes of fasting hypoglycemia during the first 2 years of life before cardiomyopathy had become apparent. A defect in carnitine uptake was demonstrable in fibroblasts and leukocytes from patients. The defect also appears to be expressed in muscle and kidney. Concentrations of plasma carnitine and rates of carnitine uptake in parents were intermediate between affected patients and normal control subjects, consistent with recessive inheritance. Early recognition and treatment with high doses of oral carnitine may be life-saving in this disorder of fatty acid oxidation.

Ornithine transcarbamylase deficiency in the male neonate has been considered to be invariably fatal because of the severity of the hyperammonemia. An extreme degree of hyperammonemia in a male neonate was brought under control by a series of exchange transfusions, prolonged peritoneal dialysis, adequate caloric intake, and a mixture of essential amino acids with an excess of aspartic acid and arginine. After the initial phase, it was possible to maintain the plasma ammonia level with dietary therapy alone, in spite of a number of complications that might be expected to cause tissue damage and increase the hyperammonemia.

Control of the plasma histidine level in histidinemia is possible with the use of an amino acid mixture free of histidine and a carefully monitored intake of histidine. This regimen is compatible with good physical growth and normal mental development. If further clinical experience demonstrates that widespread nutritional intervention in this disease is warranted, it should be possible to obtain good biochemical control.

Plasma and cerebrospinal fluid amino acid values were determined in 29 infants 9 to 30 days of age with a confirmed diagnosis of phenylketonuria. Phenylalanine concentrations in plasma and cerebrospinal fluid were markedly elevated; the degree of elevation in the cerebrospinal fluid had a significant relationship to that of the plasma. The only other significant deviations in the plasma were reductions in the threonine and tyrosine values. Cerebrospinal fluid threonine, alanine, and arginine concentrations were reduced, whereas those of serine, isoleucine, and histidine were elevated. This combined deficiency and excess of amino acids in the central nervous system may have a significant effect on protein synthesis at a time in life when this synthesis and turnover is most active.

Summary: Plasma branched chain amino acid levels and their respective ketoacid analogues were determined in seven maple syrup urine disease patients ranging in age from 12 h to 12 years. One hundred one pairs were analyzed. There was a high degree of correlation between the amino acid and its ketoacid analogue at every amino acid level. The coefficient of correlation (0.84) was highest for leucine-α-ketoisocaproic acid. The ratio of ketoacid analogue to amino acid, (0.87), was also the greatest for leucine. The close correlation implies that adequate monitoring for therapy can be accomplished by the use of the technically simpler and more rapid determination of the plasma branched chain amino acids.

In 1974, Royer et al. described a familial syndrome consisting of a short and sluggish small bowel, malrotation of the gut, and pyloric stenosis. These authors stressed the uniformly fatal outcome of their four cases, as well as other possibly unrecognized cases previously described in the literature. The present report deals with two more familial cases, of which one represents a long-term survivor of the syndrome. The intensive work of maintaining nutrition, controlling infection, and managing the complications of associated defects are described.

Two trials of oral neomycin therapy resulted in the reduction of the urinary excretion of methylmalonic acid and a fall in the plasma level of this metabolite in a child suffering from methylmalonic aciduria. It is quite probable that the antibiotic effect on the gastrointestinal bacteria resulted in decreased propionate production; propionate is the immediate precursor of methylmalonic acid. This therapy might be of special benefit during periods of acute acidosis in this disease.

The clinical features of argininemia in two cousins included hyperactivity, spasticity, ataxia, retardation, and repeated attacks of hyperammonemia. Study of a large kindred suggests that arginase-deficiency is transmitted as a Mendelian recessive. Treatment with an essential amino acid mixture with the total nitrogen intake limited to the requirement, controlled the hyperammonemia, reduced the plasma arginine level, and permitted a marked clinical improvement. There has been a significant increase in intelligence levels; the previously retarded children are now approaching the normal range of function.

Cystine deficiency was inadvertently produced in a boy receiving specific dietary therapy for homocystinuria. This was manifested as a loss in weight, the reappearance of significant amounts of homocystine in the plasma and urine, and the elevation of the plasma methionine level. In addition, there was a significant reduction in the level of cystine in the plasma. This reduction in plasma cystine level differentiates cystine deficiency from loss of biochemical control due to failure to keep the prescribed diet. The addition of cystine to the regime of this child, without any other dietary modification, resulted in a complete remission.

pregnancy and a normal spontaneous delivery. Apgar scores were 9 and 10 at 1 and 5 minutes. Birth weight was 3.8 kg and physical examination was completely normal. At three hours of age the plasm a arginine level was .4.0 mg/dl (normal average 1.3) and arginase activity was not detectable in the erythrocytes. Repeated /tssays of erythrocyte arginase activity all revealed less than 5% of normal activity. Red blood cell arginine level determined just before the initiation of therapy was 4.22 mg/dl (normal 0.4). The infant was given glucose water until the essential amino acid mixture was started at 18 hours of age; a milk formula was never offered. The mixture was fed in an amount to provid? the equivalent of 2 gm of protein per kg of body weight. It was supplemented with Mead Johnson product 80056* to furnish a total caloric intake of 125 calories/kg. This was the only feeding for the first four months of life. After this, fruits, low protein vegetables and rice cereal were introduced. The diet was later supplemented with various protein-free products such as special bread, cookies, pasta, etc. The natural protein intake has never exceeded 5 grams/day, which provides an estimated 250 to 300 rag/day of arginine.

We were gratified to see our experience with the effectiveness of oral neomycin therapy in reducing the levels of MMA in methylmalonic acidemia confirmed by Duran, Bakker, Wadman and van Sprang, and were, of course, distressed to learn of any possible untoward effect in their small patient. We should like to point out, however, that the acidosis of neomycin therapy reported by Asatoor is mild, and is a function of the loss of extra bicarbonate in a more voluminous stool.

A lack of correlation between clinical symptoms and the degree of enzyme activity in propionic acidemia has been reported; siblings of symptomatic patients have had greatly reduced propionyl CoA carboxylase activity without any clinical sequellae. The opposite situation occurred in two sisters who had typical severe symptoms and marked elevation of serum propionic acid levels but lymphocyte enzyme activity was 1/2 normal. Two male siblings had succumbed in infancy with symptoms suggestive of the same disorder. There was neither clinical response nor enzyme enhancement after biotin supplementation. Enzyme activity of the father was normal but that of the asymptomatic mother was in the same range as the two daughters'.This was of particular interest in that we have observed reduced activity of the father and normal activity of the mothers of other patients with propionic acidemia who had minimal enzyme activity. These findings suggest a variant of the disorder with an unusual pattern of inheritance.

To the Editor.— Although azaribine has been shown to be an effective drug in the treatment of psoriasis, the Food and Drug Administration has recently prohibited the use of this antimetabolite because of the possibility of an associated increased incidence of thromboembolism. We present a hypothesis and some preliminary supporting data that may explain this adverse effect. In 1969, high dosages of azaribine (400 mg/kg/day) were shown to result in the urinary excretion of various amino acids, including homocystine. 1, 2 Until recently, this appeared to be a mere biochemical curiosity. However, with the report of vascular complications in patients who were on a regimen of azaribine, similar to those complications found in patients with hereditary homocystinuria, we screened our patients who were receiving azaribine for the presence of homocystine in the blood and the urine. As homocystine is normally not present in either the blood or the urine, detectable

We are reporting the unusual case of a 36 yr. old man who at age 3½ yr. had an ileocecal intussusception which required massive resection of his small and part of his large bowel. At age 7 yr. he underwent a second resection of the gut, leaving only 30 cm. of proximal small intestine. Since then his growth remained extremely stunted. At age 18 yr. his height was 117 cm., and at 35 yr. it was 122 cm. (corresponding to a mean height of a 6 yr. old boy), while his bone age was 13 yr. (± 11 m.SD). A growth hormone deficiency was excluded. From age 10 yr. onward he developed tetany, secondary to hypocalcemia, hypomagnesemia, anemia due to intestinal blood loss, and vit. B12 deficiency. At age 35 yr. his serum Zn was low normal, but levels of Cu, Cr, Se and Mn were very low. After a period of rapid deterioration (weight loss, hypoproteinemia), the patient finally accepted home parenteral nutrition. This was continued for 15 months and resulted in a weight gain of 16 kg. and an increase in height of 8.5 cms. A small increment in serum somatonedin-C was observed (16 to 29 ng/ml). Concomitantly, he developed secondary sexual characteristics (Tanner III), with a surge in serum testosterone levels up to 926 ng/dl, from a low of 20 ng/dl (normal 300-900). Serum Ca and Mg levels were normal. We conclude that growth failure and delayed puberty, secondary to prolonged malnutrition, will respond to appropriate intravenous alimentation, even at an advanced age.

The enzyme phenylalanine hydroxylase is almost exclusively limited to the liver although some activity may be found in the kidney and the intestinal mucosa. Determination of this enzyme activity necesitates, therefore, the use of an invasive procedure (liver biopsy). Milstien and Kaufman have measured tritiated water produced from a pentadeuterated phenylalanine in rats and penta tritiated phenylalanine in a single patient to obtain in vivo activity of this enzyme. We have studied phenylalanine hydroxylase activity in rabbits using a carbon 4 tritium tagged phenylalanine which yields one mole each of tyrosine and tritiated water. A load of 150 mg/kg of phenylalanine and 10 mcc/kg of tritiated phenylalanine was given. The tritiated water formed was determined for 3 hours. The reaction is linear up to 4 hours, Y=885.2618X + 17463.15; r=0.980963 p .001. After informed consent frctn the involved parties, and approval by the institutional Research Review Committee were obtained, the test was carried out on one adult control, one obligate heterozygote mother and her adult PKU daughter. The production of tritiated water was .439 umole/ml of plasma/hour for the control, 0.125 for the obligate heterozygote and less than 1% of the control value for the affected patient. The radiation exposure is minimal and was calculated to be less than a chest X-Ray. We conclude that phenylalanine hydroxylase activity can be safely determined in vivo with a load of tagged ring 4 phenylalanine.

Although inadequate plasma volume expansion (PVE) and decreased fetal weight have been shown to occur following maternal malnutrition in rats, whether this association is one of cause and effect is unknown. By artificially expanding blood volume in malnourished animals on the 14th or 17th day of gestation with a single IV injection of whole rat blood we have been able to examine this relationship. Results demonstrate that when pregnant rats are restricted to a 5.5% protein diet throughout pregnancy but injected with 5 ml of virgin rat blood on day 14, plasma volume expands to levels seen in nonrestricted animals and the pups are of normal weight at term. By contrast if the PVE is performed at 17 days gestation growth failure will occur. Thus the growth failure attendant to maternal protein restriction can be prevented by artificially expanding blood volume early in pregnancy. These data suggest that a causal relationship exists between lack of maternal plasma volume expansion and fetal growth failure in dams subjected to protein malnutrition.

Propionyl CoA carboxylase activity was determined in patients and obligate heterozygotes for propionic acidemia and control subjects. The assay was performed on lymphocytes using 14C sodium bicarbonate. There were 5 males and 5 females in the heterozygotes group and 5 males and 4 females in the control group. The table lists the propionyl CoA activity in picomoles/minute/mg protein. Obligate male heterozygotes demonstrated activity one half of normal. However the activity of female heterozygotes was in the same range as that of controls. Although complementation studies could not be performed it is highly unlikely that any of these patients fell into the PccC group in which the heterozygotes do have normal activity since all the patients' fathers did demonstrate the reduced activity. This difference in activity between male and female heterozygotes has also been observed in MSUD. Although there is no explanations for the sex difference the finding is of interest in that it demonstrates that lymphocyte enzyme activity cannot always be relied on to determine the heterozygous state.