Distribution of sphingosine 1-phosphate, a bioactive sphingolipid, in rat tissues.

Although a growing number of reports on the bioactivities of sphingosine 1-phosphate (Sph-1-P) in various systems have been appearing recently, current evidence for the involvement of Sph-1-P in signal transduction or cellular function(s) consists largely of data on cellular and biochemical effects of exogenous Sph-1-P. In this study, we measured Sph-1-P contents in various rat tissues. When the amount of this sphingoid base was measured by its N-acetylation into [3H]C2-ceramide 1-phosphate with [3H]acetic anhydride, we could detect Sph-1-P in all rat tissues examined. We also got unexpected findings that Sph-1-P exists most abundantly in testis = intestine > spleen (in the order of Sph-1-P abundance when its amounts were adjusted to the phospholipid levels). Our new data on Sph-1-P distribution in rat tissues may imply novel bioactivities for Sph-1-P.

Quantitative measurement of sphingosine 1-phosphate in biological samples by acylation with radioactive acetic anhydride.

We describe here in detail the development of a method to quantitatively measure sphingosine 1-phosphate (Sph-1-P), a bioactive sphingolipid. Sph-1-P was first extracted from cells into the upper aqueous phase under alkaline conditions by Folch's phase separation and then reextracted into the lower chloroform phase under acidic conditions. This phosphorylated sphingoid base extracted was quantitatively converted to N-[3H]-acetylated Sph-1-P, that is [3H]C2-ceramide 1-phosphate (C2-Cer-1-P), by N-acylation with [3H]acetic anhydride. The [3H]C2-Cer-1-P formed with the acylation was resolved by thin-layer chromatography, detected with autoradiography, and quantitated by scraping the corresponding band and counting its radioactivity with a scintillation counter. This assay allows quantification of Sph-1-P over a range from at least 100 pmol (often 30 pmol) to 10 nmol (the highest level tested). The utility and validity of our assay were demonstrated using human platelets. The amount of Sph-1-P in platelet extracts was proportional to the cell number and calculated as 141 +/- 4 pmol/10(8) cells (mean +/- SD, n = 3), which was about four times higher than that of sphingosine. The potent agonist thrombin did not affect the total Sph-1-P amounts in platelet suspensions but induced the release of Sph-1-P stored in the cells into the medium.

Neonatal Fanconi syndrome due to deficiency of complex III of the respiratory chain.

Fanconi syndrome is an important presentation of respiratory chain disease. We report three patients who presented in the neonatal period with Fanconi syndrome, lactic acidosis and intrauterine growth retardation. In all three patients the major biochemical defect was in complex III of the mitochondrial respiratory chain, a relatively uncommon defect. The diagnosis could only be made by muscle biopsy as the defect was not expressed in cultured skin fibroblasts. Treatment with vitamins C and K3 and ubiquinone did not alter the course of the disease and all patients died before the age of 4 months.

The radiological features of hemimegalencephaly including three cases associated with proteus syndrome.

We report the radiological appearances of 5 children with hemimegalencephaly. There are few reports of this rare condition in the radiological literature. Two of the children have hemimegalencephaly as an isolated finding while the other three have Proteus syndrome. Four children have seizures which commenced within the first 6 months of life and two of these subsequently required hemispherectomy. In addition to the typical radiological features of hemimegalencephaly there was a high incidence of other brain anomalies. These include hypoplasia of the corpus callosum and crus cerebri, grey and white matter calcification and cortical migration/organisational disorders.

Sonographic and pathological features of callosal hypoplasia in non-ketotic hyperglycinaemia.

A boy was born at 36 weeks' gestation weighing 2450 g. Though his Apgar score was 9 at birth, by the age of 48 hours he required artificial ventilation. He was deeply unconscious with complete lack of muscle tone, and non-ketotic hyperglycinaemia associated with secondary hypoplasia of the corpus callosum was confirmed by biochemical tests. The cranial ultrasound scan features correlated well with the neuropathological findings and may be helpful in the early detection of this incurable condition.

Fatal lactic acidosis in infancy with a defect of complex III of the respiratory chain.

We report our studies on the metabolic defects which caused a newborn infant to present with a severe lactic acidemia (25 mM) and to die on the 3rd d after birth despite intensive supportive measures. The mitochondrial fractions prepared from skeletal muscle and liver oxidised NAD+-linked substrates and succinate slowly. Spectrophotometric assays for complexes I, II, and III of the respiratory chain demonstrate a specific defect of complex III in the skeletal muscle and liver mitochondrial fractions. The concentrations of cytochrome b were 75% lower in the skeletal muscle and heart mitochondria than in control preparations. The amount of non-heme iron sulphur protein of complex III was low in skeletal muscle, liver, and heart. This case differs from previous reports of complex III deficiency in three respects: the patient presented in the neonatal period, the defect was expressed in several tissues, and it was fatal.