We retrospectively reviewed clinical and biochemical data of four patients diagnosed with tyrosinaemia type II. Diagnosis was established by high plasma tyrosine and normal plasma phenylalanine levels using plasma high-pressure liquid chromatography and tandem mass spectrometry. All patients were mildly mentally retarded and had painful non-pruritic and hyperkeratotic plaques on the soles and palms. There were no ophthalmic symptoms. The patients dramatically responded clinically and biochemically to a diet restricted in tyrosine and phenylalanine
1. Somatostatin (SRIF, somatotropin release inhibiting factor), at a concentration of 2 x 10(-8) M (32 ng/ml) decreased the rat of alanine release (approximately 45%) and increased glutamine release (approximately 30%) in in vitro preprations of m. extensor digitorum longus (EDL) muscle from 35--40 day old Wistar rats. These effects of SRIF were observed under both aerobic and anaerobic conditions. 2. SRIF increased the formation of 14CO2 from alanine but not from glutamine, glutamate, leucine, isoleucine or valine. 3. The incorporation of alanine, glutamine, glutamate, leucine, isoleucine and valine into muscle protein was unaffected by the presence of SRIF.
Biotinidase deficiency is an autosomal recessive genetic disorder which is not uncommon in the Saudi population. Biotinidase is responsible for biotin recycling and biotin is an essential cofactor for activation of the carboxylase enzymes. Absence of biotinidase leads to infantile or early childhood encephalopathy, seizure disorder, dermatitis, alopecia, neural deafness and optic atrophy. The disease can be diagnosed by simple fluorometric enzyme assay. Treatment with biotin is both cheap and simple, resulting in rewarding clinical recovery and normalization of the biochemical, neuroradiological and neurophysiological parameters. If neglected, however, a patient may die of acute metabolic acidosis or may suffer from permanent neural deafness and optic atrophy, with mental and motor handicap. We describe the detection and treatment of 20 cases of biotinidase deficiency in our hospital and recommend the introduction of a neonatal screening programme for this disorder
Murine trisomy 16 (Ts16) has been proposed as a model to study Down’s syndrome (DS), because mouse chromosome 16 carries several genes homologous to loci on the human chromosome 21. A characteristic of DS is an increased sensitivity to adrenergic ligands. We have tested the sensitivity of murine Ts16 fibroblasts and embryonic cells to epinephrine and isoproterenol. A 2-4-fold reduction in the accumulated cyclic AMP (cAMP) was observed in response to these ß(1)-adrenergic ligands. Since these cells also accumulated a 2-4-fold reduced amount ofcAMP in response to prostaglandin E(1), the data suggest that a change in the adenylcyclase of these cells exists which is not seen in cells derived from DS individuals. Therefore, murine Ts16 cells do not appear to constitute an appropriate model to study the altered adrenergic function of DS.
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