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Variations in expression and activity of a beta-galactoside-specific lectin were quantified during postnatal maturation of the rat brain. Lectin expression, estimated from enzymatic immunoassay data, and lectin activity, evaluated by rabbit erythrocyte agglutination, are higher in the brains of young animals (5 days after birth) than in older ones (2 months of postnatal life). Concurrently, modifications in glycosylation during cellular differentiation were detected by affinoblotting using a biotinylated derivative of a beta-galactoside-specific brain lectin. This study shows that membrane and cytosolic glycoconjugates of the rat brain bear appropriate beta-galactoside moieties which may be recognized by an endogenous lectin expressed in the tissue itself in relation to brain maturation. The observed variations in the expression of lectin and complementary glycoconjugates can be correlated with significant events of rat brain development.

Niemann-Pick type C disease diagnosed in adult neurology departments may be infantile or juvenile forms with prolonged life span or forms starting at adolescence or adulthood. The evolution is generally slower compared to the infantile cases. Psychomotor retardation is practically constant. Cerebellar ataxia and extrapyramidal manifestations are often found in opposition to pyramidal symptoms. Supranuclear ophthalmoplegia with a down-gaze failure is nearly constant. Cataplexy and other types of seizures may be found during the evolution of the disease. In some cases a psychosis may be the only manifestation for several years; the treatment by psychotropic drugs raises the question of a superimposition of a drug-induced lipidosis. Hepatosplenomegaly is often discrete, contrary to infantile cases. Foam cells or sea-blue histiocytes are a general feature of the disease. Although the primary defect is unknown, diagnosis must be confirmed by the defect in cholesterol esterification from exogenous cholesterol.

Cognitive evaluation of 6 cases of adult adrenoleukodystrophy (ALD) included in a brain magnetic resonance (MR) study are reported: 2 males with adrenomyeloneuropathy and 4 women heterozygous for ALD. Cognition was normal in 4 and MR scan in 2 of them. In the 2 others, there were mild modifications of the white matter. One patient suffered of visual retention disturbances with abnormalities of the white matter in MR scan. In the last, cognitive decline was observed; MR scan showed atrophy of cortex and corpus callosum and periventricular high signal areas. Comparison with leukoaraiosis in healthy adults and with multiple sclerosis suggests that there is probably a relationship between cognition and extension of brain MR abnormalities. Time of appearance and frequency of cognitive dysfunction might be explained by the natural history of each of these diseases.

The clinical and biochemical characteristics of metachromatic leukodystrophy (MLD), true adult forms and late juvenile forms which are still living at adulthood, are reviewed as they both are observed in adult Neurology and Psychiatry departments. Mental deterioration is often the first symptom, evolving progressively; and dementia finally occurs. The latency before the appearance of neurological objective symptoms may be long and extend for several years. In many cases, the behavioral abnormalities are the first symptoms. Some of these forms have been diagnosed as schizophrenia. Very seldom, neurological symptoms, especially ataxia, occur without cognitive or psychiatric disturbances. Most of these cases have pyramidal and cerebellar symptoms, at diverse degrees. Seizures can also occur which is some cases can be early symptoms associated to mental deterioration. The association of central and peripheral neurological symptoms is very characteristic of MLD. The peripheral neuropathy is not generally clinically evidenced, but is rarely missing electrophysiologically. Arylsulfatase A determination should be performed for diagnosis as a first step, and confirmed by the accumulation of sulfatide, either by quantitative determinations in urine or by the sulfatide loading test. It is as yet not clear why certain forms have a rather rapid evolution in 5 years, and others have a very protracted course during decades.

The presence of an endogenous 'cerebellar soluble lectin' (CSL) involved in myelin compaction and myelination was analyzed in the dysmyelinating mutant mice quaking and jimpy. The primary defect in these mutations with severe hypomyelination is still unknown in the quaking mutant but results from a single mutation in the proteolipid protein gene in the jimpy mutant. Both immunocytochemical and immunoblotting techniques showed that CSL was not considerably reduced in its expression in the myelin fraction purified from adult quaking mutants. Furthermore, the myelin-associated glycoprotein and an axonal glycoprotein with a relative molecular weight (Mr) of 31 kilodaltons (kDa) were not decreased in quaking mice. This contrasted with several glycoproteins of Mr 23, 18, 16 and 12 kDa which were absent from the purified quaking myelin. In myelin preparations obtained from the jimpy mutant the CSL level was considerably reduced. This defect did not result from a deficient synthesis of CSL. However, as in the quaking mutation low-Mr glycoproteins were lacking. The nature of the low-Mr glycoproteins absent in quaking and jimpy mice is discussed in relation to previous reports on myelin glycoproteins. In the various mutants, due to different primary mutations, a similar absence of myelin compaction was observed, which could be associated with a deficient level of low-Mr glycoproteins. It is thus postulated that these molecules are essential for ensuring myelin compaction as ligands for the endogenous CSL.

Transport of subcutaneously injected [1-14C]-stearic acid through the blood-brain barrier is compared with endogenous biosynthesis (within the brain) during postnatal brain development in mice. The uptake is very important during glial cell multiplication and myelination; endogenous microsomal synthesis is most active during myelination, soluble de novo mechanism is prominent during cell multiplication (mitochondrial systems are not directly related to these events). A parallel is drawn between myelin fatty acids, microsomal synthesis and uptake from the blood.

Neonatal rat Schwann cells isolated in culture proliferate slowly and do not form a basement membrane although they express laminin continuously. We demonstrate here that isolated Schwann cells express other basement membrane components, including entactin and heparan sulfate proteoglycan. Treatment with ascorbate, and to a lesser extent with cyclic adenosine 3',5'-monophosphate, modulates the synthesis of extracellular matrix components by cultured Schwann cells. After this treatment, fibronectin and collagen type IV are detected on the Schwann cell surface, which form, with the other components, a membrane-bound extracellular matrix. Electron microscopy shows that these elements are organized in a filamentous matrix which resembles a basement membrane and may be a precursor form of a basement membrane. We also show the effect of complete basement membrane matrices on Schwann cell behavior in culture. These matrices support Schwann cell proliferation in both serum-containing and serum-free media. The extracellular matrix from endothelial cells mimics fibronectin and induces a flat phenotype whereas the reconstituted basement membrane gel from the EHS tumor mimics laminin and allows an elongated phenotype. Thus, the basement membrane matrices interact with Schwann cells in vitro and may play an important role in Schwann cell proliferation in vivo.

The biochemical analysis of a case of infantile neuronal ceroid lipofuscinosis, as determined by clinical and neuropathological findings, is presented. A diminished amount of solids is found, the amount of lipids is 30% of the normal as expressed in lyophilized tissue. The yield of myelin isolated by the density gradient is 1.8% of the normal. Phospholipid patterns show a reduction in ethanolamine phosphoglyceride, N-acetylneuraminic acid is extremely low and sphingolipids are largely reduced, cerebrosides being most affected (2.5% of the normal). In cerebrosides and sulfatides the decrease in very long chain fatty acids is important, but the deficiency in any type (including hydroxy compounds) is not too dramatic. According to the aspect under electron microscopy, the density profile, and the biochemical composition of the subfractions, isolated myelin is close to normal. The loss of the myelin sheath appears to reflect a Wallerian degeneration in the CNS: myelin loss is a secondary effect. This disease, from a biochemical point of view, seems to be the ideal control for leukodystrophies.

Analysis of myelin from a leukodystrophic brain was performed (Pelizaeus-Merzbacher disease, classical type). Myelin recovery was 7% of normal, when isolated by ultracentrifugation. Electron microscopy showed a great amount of loose lamellae, with less thick sheaths and periodicity close to normal. This myelin contains fewer lipids than normal, sphingolipids and plasmalogens being reduced. FAtty acids from phospholipids are essentially normal, however enols from plasmalogens are largely reduced. Purified sphingolipids (cerebrosides, sulfatides and sphingomyelin) present a considerable diminution in very long chain fatty acids; the ratio of very long chain fatty acids (over C18) on shorter chains is 1% of the normal value for saturated fatty acids and 2% for the monounsaturated homologues. Protein analysis showed that basic protein and proteolipids were reduced, Wolfgram proteins being relatively increased.

In the early sixties, remyelination was first observed in animal models of demyelination and described a few years later in multiple sclerosis. The spontaneous remyelination process is now well documented. Remyelination by transplantation of myelin-forming cells has been attempted. Transplanted Schwann cells can myelinate a central nervous system lesion but the remyelination is limited to the area of implantation. Oligodendrocytes or precursor cells are much more invasive and have been shown to migrate from the implantation site to the lesion at a distance of several millimeters. Thus, remyelination by transplantation of myelin-forming cells is possible at least in animal models, the oligodendrocytes being more efficient.

Solid fragments of olfactory bulb from new-born normal (B6CBA and C57BL6) mice were implanted into new-born shiverer (shi/shi) brains. The shiverer mouse being characterized by the absence of myelin basic protein (MBP), myelination due to implanted oligodendrocytes can be detected in the shiverer brain using an antiserum anti-MBP. Observation of sagittal sections of the host brains revealed very extensive areas of normal myelination from the level of the graft (rostral thalamus) up to the caudal brain (diencephalon, cerebellum, pons). Thus, oligodendrocytes contained in the implant migrate out of the graft over long distances in the host brain, before they differentiate and synthesize myelin. These results raise the question of the behaviour of oligodendrocytes in normal development.

The blood-brain relationship for stearic acid varies during development. Subcutaneously injected [1-14C]-stearic acid is taken up by brain. Age-related changes in the metabolism of stearic acid have been determined in mouse brain from birth to maturity. Total lipid radioactivity reaches a maximum at 18 days of age and decreases afterwards until adulthood. However, specific radioactivity presents the highest value at 1 day of age and declines from then on. At any age, the injected acid is taken up and partly metabolized in the brain, either by elongation or by degradation in situ and resynthesis of new fatty acids; it is also desaturated, and the oleic acid thus formed is eventually elongated. The labeled stearic acid is incorporated into brain lipids with a different pattern according to the age of the injected animal.

As already demonstrated by immunohistochemistry, oligodendrocytes from newborn normal mice are able to survive, migrate and myelinate when transplanted into the newborn shiverer (shi/shi) mouse brain. The survival of the grafted cells and their interaction with the host brain were studied at different times after transplantation. Normal myelin was found in the host parenchyma basing our observation on the morphological difference between normal and shiverer myelin: the shiverer myelin deprived of major dense line appears uncompacted as compared to normal myelin. Myelin formed by transplanted oligodendrocytes was detected around the graft and, after immunohistochemical prelocalization, at considerable distance from the site of implantation. Normal and shiverer myelin were detected around axons adjacent to each other or around the same axon. These results confirm and extend at the ultrastructural level our previous data obtained by immunohistochemistry.

Intrauterine growth retardation (IUGR) was obtained by ligation of one uterine artery on day 17 of pregnancy. Neurons isolated from IUGR rats presented a decrease of monounsaturated fatty acids and an increase of omega-3 serie fatty acids, concomitant to a decrease of omega-6 serie fatty acids. Oligodendrocyte content in monounsaturated fatty acids was also reduced; important modifications occurred in their polyunsaturated fatty acid distribution. Myelin was close to normal in adults, slightly altered in young. Synaptosomes presented slight disturbances in polyunsaturated fatty acid distribution. Thus, the fatty acid composition was an index of maturation stage and nutritional status of developing brain membranes.