Rosalba Gornati

Enzyme replacement treatment in type 1 and type 3 Gaucher's disease

The development of intravenous enzyme-replacement treatment for Gauchers disease has changed life expectancy in cases without neurological involvement (type 1). The effects in patients with neurological involvement are unknown. We treated 12 Italian patients, types 1 (9) and 3 (3), with intravenous alglucerase: 70-120 IU/kg per month for type 3 and 30-60 IU/kg per month for type 1. Maintenance infusions were biweekly in patients without neurological symptoms, whereas in one symptomatic type 3 patient, infusion was weekly. All patients improved; a resumption of growth in children with growth retardation was observed and spleen and liver reduced in size. In one type 3 patient, a bone callus formed during treatment and enabled the patient to walk. Laboratory tests showed rapid increase of haemoglobin in anaemic patients, and a slower response in patients with thrombocytopaenia. In 4 patients there was temporary hypocalcaemia immediately after the beginning of treatment. Neurological symptoms were present in 1 of the type 3 patients, and electroencephalogram was abnormal in another. After 2 years of treatment, the patient with symptoms showed an improvement of psychomotor skills and of IQ from 50 to 60. Genotype analysis showed a high frequency of the 1448C mutation (54.5%). The 9 patients carrying this allele came from Italian regions which in the past had been invaded from north Europe and Scandinavia. Enzyme replacement in Gauchers type 1 can also be effective at low doses and even with a 2-week interval between infusions. This makes treatment cheaper, and reduces hospital stay for patients.

CHOLESTEROL, TRIACYLGLICEROLS AND PHOSPHOLIPIDS DURING XENOPUS EMBRYO DEVELOPMENT

Cholesterol, triacylglicerol and phospholipid content was analysed in Xenopus embryos during their early development (from day 1 to day 6). Triacylglicerols decrease significantly during the analysed stages and this can be explained by their use as energy substrate. Cholesterol and phospholipids, on the contrary, remain constant and are probably redistributed inside the embryo. The different phospholipid classes were separated by HPTLC. A constant decrease of PC and a marked increase of PS has been observed. The fatty acid composition of the single phospholipid classes has been analysed.

Total glycolipid and glucosylceramide content in serum and urine of patients with Gaucher's disease type 3 before and after enzyme replacement therapy.

The follow-up of Gauchers patients under enzyme replacement therapy is generally based both on the clinical aspects and the evaluation of haematological parameters: haemoglobin level, platelet count, acid and alkaline phosphatase activities. Spleen and liver volumes are also reliable criteria for evaluating the improvement of the patients. The determination of glycolipid excretion in the urine and/or the quantification of glycolipids in serum can also be a useful tool for the screening and the follow up of patients with lysosomal storage disease including Gauchers disease. In this paper we report the follow-up of three patients with Gaucher type 3; in order to test the efficacy of the enzyme replacement therapy with alglucerase in these patients, we evaluated the urine and plasma glucosylceramide content as a marker parallel to the clinical improvement and the decreased organomegaly.

Activities of glycolipid glycosyltransferases and sialidases during the early development of Xenopus laevis

The activities of glycosyltransferases and sialidases, together with the ganglioside content and distribution, have been extensively studied in mammals, while the informations on tissues of other animals, including amphibian, are scarce. In this paper we present data on the activities of SAT-1, SAT-2, SAT-4, SAT-5, GlcNAcT-1, GalNAcT-1, GalT-6, and sialidases studied in Xenopus laevis embryos at different stages of development. The highest activity was found at days 4 and 5 of embryogenesis for glycosyltransferases and sialidases respectively; a tentative correlation between the in vitro activity of these enzymes and the content of neutral and acidic glycolipids is discussed. (Mol Cell Biochem 166: 117-124, 1997)

Glycolipid patterns during xenopus embryo development

Glycolipid patterns have been studied during the first six days of Xenopus embryo development. Glycolipid contents showed a sharp increase more evident after the third day of development. Glucosylceramide and sulphatide are not only the most represented species, but also those which exhibit a statistically significant percentage change during early development. Among gangliosides, GD3 is the most represented specie. Two polysialylated gangliosides with not yet established structures are also present.

Effect of maternal diet on the distribution of phospholipids and their fatty acid composition in Xenopus laevis embryos

We determined the total phospholipid content, the percentage distribution of different phospholipid classes and their fatty acid composition in 6-day-old embryos obtained from Xenopus laevis females fed on two different diets. A first group of females was fed on beef liver, and a second one was nourished with commercial fish food very rich in omega-3 fatty acids. The embryos showed different patterns of phospholipids that had dissimilar fatty acid compositions. Phosphatidylinositol content was particularly affected. Due to the functional roles of this phospholipid as part of the transmembrane signaling machinery, it is possible to hypothesize that maternal diet might influence cell metabolism in amphibian embryos.

Lipids of Xenopus laevis Spermatozoa

Xenopus laevis sperm lipid composition has been studied. The cholesterol content of Xenopus spermatozoa is 194 μ/mg DNA. Their content of glycolipids and phospholipids (measured as inorganic phosphorus) is respectively 40 and 27 μ/mg DNA. The phospholipid pattern is quite homogeneous and all the principal molecular species are present. In all the examined samples, a glycolipid with low mobility, not yet structurally identified, is present. Finally, using as a probe filipin, we have observed cholesterol distribution on the Xenopus sperm plasma membrane by freeze‐fracture. In agreement with the chemical data here presented, Xenopus spermatozoa are heavily labelled by filipin. The filipin‐cholesterol complexes seem to be distributed on the entire sperm plasma membrane and appear as protuberances on the P face, suggesting that most of the cholesterol reside in the inner leaflet of the membrane.

Retinoic acid induces changes in Xenopus embryo glycolipid pattern.

Retinoic acid (RA), known for its important role in cellular differentiation, may cause a modification of glycolipid distribution characterized by a shift from globoserie towards latto‐ and ganglio‐series. In the present paper, we have investigated the modifications of the lipidic pattern after exogenous RA treatment of Xenopus embryos. We have noticed a decrease in neutral glycolipids with a parallel increase in gangliosides; the content of sulfatides does not seem to be modified. Beside the shift toward ganglio‐serie, we have also observed a redistribution inside this class of lipids. In particular, following RA treatment, the relative distribution of GD1b and GT1b increases while that of GM3 decreases.

Ganglioside long-chain base composition of rat brain subcellular fractions after chronic ethanol administration

Rats of two different ages (2 and 7 months) were treated with an ethanol-containing liquid diet for 24 days and change of the ceramide composition of gangliosides were studied in the brain synaptosomal, microsomal and myelin fractions. Greater differences were observed in the younger age, where ethanol treatment caused a significant increase of C20:1 LCB in GM1 ganglioside of synaptosomes and microsomes and in GD1a of myelin.

Glycolipid glycosyltransferase activities during early development of Xenopus: effect of retinoic acid.

Retinoic acid (RA) plays an important role in differentiation stage in which it also influences glycoconjugate metabolism. Previous work in our laboratory has shown that treatment with RA modifies glycolipid synthesis and distribution in total Xenopus embryos during development. In this study we have investigated the activity of the following anabolic enzymes involved in glycolipid biosynthesis: sialyltransferase‐1 (SAT‐1), GM3(β1,4)‐N‐acetylgalactosaminyltransferase (GalNAcT‐1) and LacCer(β1,3)N‐acetylglucosaminyltransferase (GlcNAcT‐1). These enzymes are located at the branching point of lactosylceramide (Lc2) metabolism. Enzyme activities were assayed after treatment with different doses of RA added exogenously to the medium during the first 7 days of Xenopus embryo development. Our results show that RA activates GlcNAcT‐1, the enzyme that drives Lc2to the glycolipids of the lacto‐series, and SAT‐1 that inserts Lc2in the ganglio‐series pathway. These data support our previous analysis of glycolipid pattern in Xenopus embryos after RA treatment (Rizzo et al., 1995;Cell Biol Int19: 895–901) indicating a possible correlation between the distribution of glycolipids and the enzymes involved in their metabolism.