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Biomedical subjects

G Sabetta

Publications and source records attributed to G Sabetta.

At least 37 records · Page 2Linked to original sources

Agenesis of the corpus callosum, combined immunodeficiency, bilateral cataract, and hypopigmentation in two brothers.

We describe 2 brothers with a malformation syndrome consisting of agenesis of the corpus callosum, cutaneous hypopigmentation, bilateral cataract, cleft lip and palate, and combined immunodeficiency. The clinical history of both patients was characterized by severe psychomotor retardation, seizures, recurrent severe respiratory infections, and chronic mucocutaneous candidiasis. The children died of bronchopneumonia at age 2 and 3 years, respectively. Immunological investigations showed, in one sib studied, skin anergy to recall antigens, profound depletion of T4+ lymphocytes, and serum IgG2 deficiency. Necropsy showed agenesis of the corpus callosum, hypoplasia of the cerebellar vermis, and profound hypoplasia of the thymus and of the peripheral lymphoid tissue. The distinctive features of these sibs appear to define a previously undescribed hereditary MCA/MR syndrome. The clinical and pathological findings seem to indicate, as a pathogenetic mechanism, a defect involving the embryonic organization of the central nervous system and of the immune system.

Abnormalities, Multiple↗

Ring 20 chromosome phenotype.

A baby with a 46,XY,r(20) karyotype is described. The distinguishing features of this rare chromosome anomaly are analysed in the light of the suggested r(20) syndrome.

Abnormalities, Multiple↗

Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome: low creatine excretion and effect of citrulline, arginine, or ornithine supplement.

Two patients with neonatal onset of hyperornithinemia-hyperammonemia-homocitrullinuria syndrome were studied at 4 and 2 1/2 yr of age, respectively. The aim of the investigation was to assess the effect of supplementing citrulline, arginine, or ornithine (2 mmol/kg per day) while on a protein-restricted diet. The peroral supplementation was carried out during 2 wk for each amino acid. While ammonia in plasma was not increased the supply of citrulline or arginine led to a reduction of plasma glutamine compared to ornithine supplement or to no supplement (control period). Plasmatic ornithine was raised in all instances. Homocitrulline excretion was lower with all additions compared to the control period. Adding citrulline to the diet (in contrast to supplementing arginine) did not lower tubular lysine reabsorption. A lowered creatine excretion was found which could be normalized by arginine or citrulline. The data are compatible with a product inhibition of arginino-glycine transamidinase suggesting that the enzyme is not located in the mitochondrial matrix in man. Citrulline supplement combined with a protein-restricted diet appears to allow a normal development. The additional finding of a factor VII and X deficiency in one of the patient and reports in the literature of this association in two other patients with hyperornithinemia-hyperammonemia-homocitrullinuria syndrome suggest that the genetic defect leading to the syndrome might be located on chromosome 13.

Amino Acid Metabolism, Inborn Errors↗

The spectrum of the so-called rigid spine syndrome: nosological considerations and report of three female cases.

Three female cases of the "rigid spine" syndrome are reported and associated with different nosological entities. One patient was affected by congenital muscular dystrophy and one by a morphological pattern of fibre type disproportion with type I atrophy. The third patient showed very peculiar morphological changes on a muscle biopsy specimen resembling a vacuolar myopathy, which is rarely described in association with the rigid spine syndrome. The importance of an adequate investigation of the rigid spine syndrome and the recognition of the presence or absence of cardiomyopathy, if there is to be correct genetic counselling, is discussed.

Adolescent↗

Methylmalonic acidaemia due to mutase apoenzyme defect: responsive to vitamin B12 in intact fibroblasts but not in vivo.

Congenital methylmalonic acidaemia (MMA-aemia) was diagnosed in an 8-month-old girl who presented with severe metabolic acidosis, hypoglycaemia and hyperglycinaemia. Vomiting, failure to thrive and apathy first appeared when breast feeding was replaced by a cows' milk formula at the age of 3 months. The patient, unresponsive to OH-Cbl therapy, was successfully treated with dietary protein restriction and with Shohl's solution. Aged 4 years 9 months, she is in good health. Studies in cultured fibroblasts revealed a defect of the MMA-CoA mutase apoenzyme. Mutase activity in cell extracts was barely detectable both with and without added coenzyme (Ado-Cbl). Addition of OH-Cbl to the culture medium improved overall propionate metabolism in intact fibroblasts but had no effect on mutase activity in cell extracts. These observations point to the presence of a very labile mutant enzyme, suggesting that the patient reported here may be suffering from yet another variant of MMA-aemia.

Amino Acid Metabolism, Inborn Errors↗

Cyanide insensitive oxidase in platelets of newborn infant.

The authors studied the behaviour of neonate platelet O2 consumption after the addition of pyridine nucleotide compared to adult controls. O2 consumption of neonate platelets after NADH addition was 103,2 millimicronmol O2/10(9)/hr (SE = 24,74) and in adult controls 188,8 millimicronmol O2/10(9)/hr (SE = 36,46). After the addition of NADPH O2 consumption was, respectively, 233,5 millimicronmol (SE = 46,29) and 218,3 millimicronmol (SE = 30,01).

Blood Platelets↗

Oxygen consumption in platelets of newborn infants before and after stimulation by thrombin.

The authors compared the oxygen consumption in platelets from the umbilical cord blood of 36 healthy newborn infants with that of 27 adult subjects, before and after thrombin addition (1.67 U/ml). Oxygen consumption at rest was 6 mumol/10(9)/min in adult control platelets and 5.26 in newborn infants. The burst in oxygen consumption after thrombin addition was 26.30 mumol/10(9)/min in adults and 24.90 in infants. Dinitrophenol did not inhibit the burst of O2 consumption in platelets in 8 out of 10 newborn infants, while the same concentration caused a decrease in 9 out of 10 adult subjects. Deoxyglucose inhibited the burst in O2 consumption in newborn infant and adult platelets by about 50%. KCN at the concentration of 10(-4) M completely inhibited basal oxygen consumption but did not completely inhibit the burst after thrombin. At the concentration of 10(-3) M, it inhibited both basal O2 consumption and the burst in infants and adult subjects.

Blood Platelets↗