Partial or near-total pancreatectomy for persistent neonatal hyperinsulinaemic hypoglycaemia: the pathologist's role.

AIMS: To determine whether the presence of abnormal B-cell nuclei predicts the existence of a focal or of a diffuse form of persistent neonatal and infantile hyperinsulinaemic hypoglycaemia in a series of 20 infants. METHODS AND RESULTS: Intra-operative frozen sections were performed on small specimens from the pancreatic head, isthmus and tail. In 13 cases, abnormal B-cell nuclei were identified, but even a near-total pancreatectomy was insufficient to cure some of these patients, in whom no focal lesion was detected. On the other hand, abnormal insular B-cell nuclei were not found in seven cases; based on the results of selective venous catheterization, a limited resection was performed, sufficient to cure each patient, and a focal adenomatous hyperplasia was found in each resected specimen. CONCLUSIONS: Intra-operative examination of small pancreatic specimens taken from the different parts of the gland allows one to determine the type of lesion (focal or diffuse) in neonatal onset hyperinsulinaemic hypoglycaemia, and to decide on the most appropriate surgical treatment.

[Persistent hyperinsulinemic hypoglycemia in the newborn and infants]. / Hypoglycémie hyperinsulinémique persistante du nouveau-né et du nourrisson.

Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most frequent cause of hypoglycaemia in infancy. Clinical presentation is heterogeneous, with variable onset of hypoglycaemia and response to diazoxide, and presence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplasia of pancreatic islet-like cells, whereas diffuse lesions implicate the whole pancreas. The distinction between the two forms is important because surgical treatment and genetic counselling are radically different. Focal lesions correspond to somatic defects which are totally cured by limited pancreatic resection, whereas diffuse lesions require a subtotal pancreatectomy exposing to high risk of diabetes mellitus. Diffuse lesions are due to functional abnormalities involving several genes and different transmission forms. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying potassium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the glutamate dehydrogenase gene when hyperammonaemia is associated, or another locus.

Continuous venovenous haemodiafiltration in the acute phase of neonatal maple syrup urine disease.

Maple syrup urine disease results in accumulation of leucine and its metabolites, which may lead in the long term to neurological dysfunction. In acute neonatal crises, large amounts of leucine may be removed by continuous venovenous haemofiltration. This extracorporeal technique has its risks and hazards, which increase with duration of treatment. We report three neonates in life-threatening conditions due to maple syrup urine disease, treated for not more than 12 h with various continuous venovenous techniques: continuous haemofiltration, haemodiafiltration and haemodialysis. The efficiency of and tolerance to these techniques was evaluated. For all three patients, plasma leucine levels decreased dramatically from 2186, 3818 and 2536 mumol/L to 1131, 1275 and 488 mumol/L, respectively. Leucine clearance obtained was 4.28 ml/min in haemodiafiltration. Their patients' neurological status improved rapidly and they have a normal developmental quotient at 22 months, 13 months, and 11 months of age, respectively. Tolerance was good except for hypothermia and drop in haematocrit in all cases. Haemodiafiltration management was more cumbersome and time consuming because it required continual adjustment of the substitution fluid flow rate to precisely balance inflow and outflow rates. We recommend continuous venovenous haemodialysis as the therapy of choice. It might be anticipated that improvement of this technique, by increasing dialysate flow rate and blood flow rate, will allow leucine concentration to be decreased below 1000 mumol/L within 6-8 h, whatever the initial level.

Biochemical and genetic studies of four patients with pyruvate dehydrogenase E1 alpha deficiency.

We report studies of four patients with pyruvate dehydrogenase complex (PDH) deficiency caused by mutations in the E1 alpha subunit. Two unrelated male patients presented with Leigh syndrome and a R263G missense mutation in exon 8. This mutation has previously been described in males with the same phenotype. The two other patients had different novel mutations: (1) an 8-bp deletion at the C-terminus (exon 11) was found in one allele of a young girl suffering from microcephaly and (2) a C88S missense mutation (exon 3) in a boy who only presented with motor neuropathy. These mutations were not found in the mothers of any of the four cases. Immunoblot analysis revealed decreased immunoreactivity for the E1 alpha and E1 beta subunits in three out of the four patients. These findings confirm that: (1) PDH deficiencies are genetically heterogeneous, (2) the R263G mutation is more frequent in male cases than are other mutations and this amino acid is a hot spot for gene mutations, (3) the last eight amino acids may be important for the conformation of the tetrameric E1-PDH enzyme, and (4) the amino acids at positions 88, 263 and 382-387 are essential for the linking of the alpha subunit with the beta subunit and for the activity of the holoenzyme.

Clinical outcome and long-term management of 17 patients with propionic acidaemia.

UNLABELLED: A retrospective study was performed on the clinical outcome and long-term treatment of 17 patients with propionic acidaemia diagnosed during the last 20 years in our hospital. The study group consisted of 12 patients with early onset type of disease and 5 patients with late onset. Seven (41%) patients died, five with early onset and two with late onset. The deceased early onset patients had a median survival of 0.4 years while the deceased late onset patients died at the age of 2.8 and 4 years respectively. Median age of the living early onset patients was 5.2 (1-9.25) years, the late onset patients were 4, 7 and 23 years old. Patients were all treated with natural protein restriction and in most cases carnitine and metronidazole were added. The early onset patients were almost all treated with daily home tube feeding. The mean natural protein intake of early onset patients (6.3 +/- 1.5 g/day) was significantly lower than the natural protein intake of late onset patients (17.6 +/- 5.3 g/day). Supplemental protein intake was higher in early onset patients. The general neurological outcome of our study group was satisfactory with a better outcome for early onset patients. As to growth, many patients showed a failure to thrive, this was particularly for height. The strong protein restriction during the first years of life probably contributed to this. CONCLUSION: The prognosis for patients with propionic acidaemia appeared to be satisfactory in terms of survival and outcome characteristics such as neurological and mental development. Despite these results the authors feel that the prognosis and quality of life of these patients might be improved with liver transplantation or possibly somatic gene therapy in the future.

Nesidioblastosis and persistent neonatal hyperinsulinism.

Neonatal hyperinsulinism is characterized by severe hypoglycaemia which can cause serious neurologic effects. Pancreatic morphological abnormalities involve either focal or diffuse lesions. The former can be cured by resection, whereas the latter, of uncertain pathogenesis, often require subtotal pancreatectomy. We investigated various hypotheses in an effort to explain the origin of this latter form of hyperinsulinism. We determined that nesidioblastosis, long considered to be the basic structural lesion of the diffuse form of hyperinsulinism, is not specific and does not correspond to a continuous proliferation of endocrine cells. We found that an increase in beta-cell mass can be excluded since the volume density of beta cells is not systematically higher in hyperinsulinemic infants than in controls. The hypothesis of a decrease in D cells is attractive but should be considered with due caution since the decrease of the D-cell volume density observed in hypoglycaemic infants is inconstant. Finally, the notion of beta-cell functional abnormality seems the most likely explanation since a higher quantity of proinsulin was detected within the Golgi area by a specific antibody and abnormal nuclei with abundant cytoplasm were observed in some cells. These histological abnormalities can be observed during intraoperative morphological examination. Functional activity might also be evaluated by studying the messenger RNA of proinsulin.

Peroxisome mosaicism in the livers of peroxisomal deficiency patients.

Peroxisomal deficiency disorders, which are genetically transmitted, are assumed to be expressed in all cells, and the use of cultured skin fibroblasts for diagnosis and research is based on this assumption. We describe three patients with clinical, biochemical, and microscopic evidence of a peroxisomal disorder. However, their liver displays mosaicism, i.e., parenchymal cells with peroxisomes are adjacent to cells without peroxisomes. Ten percent (volume), 8%, and less than 1% of the parenchyma possessed peroxisomes that can be identified in immunocytochemical tests for six matrix and membrane proteins performed by light and electron microscopy. In the bulk of the parenchyma, catalase is localized in the cytoplasm, and in such cells no peroxisomes are evident by electron microscopy and immunolabeling for the 43-kd peroxisomal membrane protein (PMP) in two patients; in the third case, peroxisomal membrane ghosts are present. Immunoblots of peroxisomal beta-oxidation enzymes show a pattern similar to that from patients with a generalized peroxisomal deficiency. In contrast to the clinical and biochemical signs of peroxisomal dysfunction and hepatic histopathology, cultured fibroblasts from two patients demonstrate normal peroxisomal functions, including very-long-chain fatty acid oxidation and plasmalogen synthesis.

Immunolocalization of a 43 kDa peroxisomal membrane protein in the liver of patients with generalized peroxisomal disorders.

The presence of peroxisomal membrane ghosts was examined in liver biopsies from eleven patients presenting the clinical and biochemical picture of a generalized peroxisomal disorder (Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease and variants of these syndromes). A polyclonal antibody raised against the membrane of human liver peroxisomes and recognizing a 43 kDa peroxisomal membrane protein (PMP) was used. In human control liver the antibodies react in a distinct and specific way with the peroxisomal membrane. Two types of organelles with an immunoreactive membrane were identified in the liver parenchymal cells of the patients: organelles containing an electron-dense core and organelles with electron transparent contents. Both types may co-occur in the same patient; in two patients they were found in the same cell. The organelles are rare, and their number varies between patients. The first type possibly corresponds to the previous morphological description of aberrant peroxisomes in the liver of patients with Zellweger syndrome, neonatal adrenoleukodystrophy and infantile Refsum disease. The empty looking organelles have not been reported previously in the liver, some of the "empty" organelles seem to be enclosed by a double membrane. Morphometrical analysis in three patients indicated that both types of organelles (corrected mean d-circle 0.271-0.306 micron for the "empty" and the dense core organelles, respectively) are smaller than the peroxisomes in postnatal control liver and in fetal liver. In one patient (infantile Refsum disease) immunoreactive organelles were not detected. The organelles with the electron-dense core were not found in two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aberrant splicing of exon 6 in the pyruvate dehydrogenase-E1 alpha mRNA linked to a silent mutation in a large family with Leigh's encephalomyelopathy.

Pyruvate dehydrogenase (PDH)-E1 alpha deficiency has recently been studied at the molecular-genetic level. The gene is situated on the X chromosome. We report on an unusual mutation in a familial E1 alpha deficiency. In fibroblasts, PDH deficiency was diagnosed in a young infant presenting with Leigh's encephalomyelopathy and in a maternal nephew with episodes of "malaises." In the two affected children as well as their mothers we found a silent mutation in exon 6 of the PDH-E1 alpha and an aberrant splicing of exon 6 in some of the cDNA clones. This case emphasizes the need for both genomic and cDNA analysis in cases where a PDH-E1 alpha deficiency is strongly suspected.

Clinical outcome of long-term management of patients with vitamin B12-unresponsive methylmalonic acidemia.

We performed a retrospective study of all patients with methylmalonic acidemia diagnosed during the past 20 years. Only those patients who were nonresponsive to vitamin B12 in vivo and in vitro were included. The final study group consisted of 26 patients, of whom 16 had a neonatal (early) onset; in 10 patients the diagnosis was made after 2 months to 2.2 years (late onset). Of the early-onset patients, 14 (87%) died, with a mean survival time of 1.5 years (range, 10 days to 2.5 years), whereas four of the late-onset patients (40%) died (range, 1.2 to 15 years). At present, eight patients are alive; their mean age is 4.6 years (range, 1 to 10 years). In the early 1970s, treatment was based on the principles of treating patients with phenylketonuria: restricting natural protein intake and supplementing essential amino acids, vitamins, and trace elements. After about 1980, nasogastric tube feeding became a mainstay of the therapy, natural protein restriction became stricter, and the use of essential amino acid mixtures diminished. Carnitine was added to the therapy and, in later years, metronidazole. Since these changes were implemented, the number of episodes of metabolic decompensation and hospitalizations has decreased. Mean survival time of the patients, in particular those with early onset, has only slightly improved, partly because of psychosocial problems in many of these families. Almost all the patients, especially those with early onset, had some degree of neurologic impairment and mental retardation, and many patients were at less than 2 SD for weight or height or both. In contrast, the neurologic and mental status of the late-onset patients was frequently normal, and their weight and height were more often within normal limits. Our results show that the treatment of methylmalonic acidemia still poses considerable problems; despite intense medical efforts and familial stress, the prognosis for the early-onset patients is disappointing. The patients with late-onset disease, however, appear to have a fairly good prognosis with the present therapeutic approach. Liver transplantation or possibly genetic therapy might improve our results in the future.

[Protocol of metabolic investigations in hereditary metabolic diseases]. / Protocole d'investigations métaboliques dans les maladies héréditaires du métabolisme.

The authors describe a laboratory investigations protocol to be used by pediatricians facing conditions suggestive of inherited metabolic disorders. This protocol includes: 1) an emergency screening to be systematically performed during the acute clinical phase; 2) samplings to be kept frozen for possible secondary specific investigations according to the results of the emergency screening. In addition a perimortem protocol is also presented, to be applied in every lethal situations in which an inherited metabolic disorder is suspected. The equipment required in order for the clinician to properly perform the different investigations is also described.

Cutaneous manifestations of methylmalonic and propionic acidaemia: a description based on 38 cases.

Methylmalonic and propionic acidaemias are rare metabolic disorders with an autosomal recessive mode of inheritance. A number of aminoacidopathies may have cutaneous manifestations, but these are usually absent in methylmalonic and propionic acidaemia. We have studied 38 children with propionic and methylmalonic acidaemia in the last 10 years at the Hôpital Necker-Enfants Malades. Thirteen had cutaneous manifestations: acute superficial scalded skin and superficial desquamation, bilateral and periorificial dermatitis, psoriasiform eruptions, and alopecia. The relative uniformity of these manifestations (scalded skin and desquamation after metabolic decompensation, chronic bilateral and periorificial dermatitis) suggests that methylmalonic and propionic acidaemias should be included in the category of aminoacidopathies with cutaneous manifestations. All these patients were suffering from severe forms of these diseases, with no residual enzyme activity, and they were all subjected to a very severe natural protein-restricted diet. These cutaneous manifestations may therefore either be part of a complex multideficiency syndrome, or be due to the enzyme deficiency itself.

Contribution of odd-chain fatty acid oxidation to propionate production in disorders of propionate metabolism.

Whole-body propionate and protein kinetics and energy substrate metabolism were studied in five metronidazole-treated patients with propionic or methylmalonic acidemias by the use of a primed, 4-h constant infusion of [1-13C]propionate and L-[O-2H5]phenylalanine combined with indirect calorimetry. Measurements were performed during fasting and carbohydrate feeding, successively, to assess the contribution of odd-chain fatty acid oxidation to total propionate production. Fat oxidation decreased from 490 +/- 179 to 57 +/- 49 mumol.kg-1.h-1 (P < 0.05) as a result of feeding. Propionate appearance rate was 38.6 +/- 8 mumol.kg-1.h-1 during fasting and decreased to 22.6 +/- 5 mumol.kg-1.h-1 (P < 0.05) on the carbohydrate diet. Precursor amino acid catabolism did not change significantly (22 +/- 5 vs 21.2 +/- 5 mumol.kg-1.h-1), suggesting that the 41% reduction in propionate production observed in response to feeding was related to the suppression of fatty acid oxidation. Therefore, significant therapeutic gains may be expected from the use of diets aimed at reducing lipid oxidation.