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Biomedical subjects

J M Bourre

Publications and source records attributed to J M Bourre.

At least 19 recordsLinked to original sources
PubMed1979

A spin-label study of sciatic nerves from quaking, jimpy and trembler mice.

The spin labels, 5-nitroxide stearic acid and 16-nitroxide stearic acid were incorporated into whole sciatic nerves dissected from normal, quaking, jimpy and trembler mice. With 5-nitroxide stearic acid, we have studied the thermal variation of the maximal apparent coupling constant (T) between 0 degrees C and 50 degrees C. Within this range of temperatures, we obtained identical values of 2 T for nerves from normal and jimpy mice, whereas 2 T was smaller for nerves from quaking and trembler mice. With 16-nitroxide stearic acid, composite spectra were recorded, particularly in the high-field range. A line characteristic of myelin was clearly observed in the spectra of nerves from normal and jimpy mice; its intensity was somewhat less in nerves from quaking mice and much less in spectra from trembler mice. A shoulder in the principal highfield line of the spectrum is modified only with nerves from jimpy mice. The results agree well with those obtained by electron microscopy, which reveal normal myelination in nerves from jimpy mice, a slight modification of the myelin from those of quaking mice and a practically complete demyelination in peripheral nerves from trembler mice. However, the structure of the nerves of jimpy mice also seems to be modified at an, as yet, undetermined level.

Animals↗
PubMed1979

The lipid composition of rat brain aggregating cell cultures during development.

The lipid and fatty acid composition of rat brain was studied during its development both in vivo and in an aggregating cell culture system. Although the amount of lipid present in the cultures was very low, the increase in glycolipid content corresponded closely to the period of intense myelin formation. Very long chain fatty acids (hydroxylated and unsubstituted) were present in 41-day cultures. In comparison to the in vivo situation, myelination was delayed in vitro and, after 40 days in culture, cholesterol esters were 5-fold higher than in vivo, indicating that demyelination was occurring.

Animals↗
PubMed1979

In vivo incorporation of exogenous [1-14C]stearic acid into neurons and astrocytes.

Exogenous stearic acid is needed to synthesize the membranes of neurons and astrocytes. Subcutaneously injected [1-14C]acid is taken up through the 'blood brain barrier' and incorporated into lipids of both cell types, the specific radioactivity being higher in astrocytes as compared to neurons (2200 and 800 cpm/mg proteins, respectively), 20 h after injection. Phospholipids contain high amount of radioactivity (80% in astrocytes, 65% in neurons); glycosphingolipids contain low quantities of label in the two cell types. The injected acid is partly metabolized in the brain by elongation and desaturation (thus providing very long chains, saturated mono-unsaturated and poly-unsaturated); it is also partly degraded into acetate units (utilized for synthesis of palmitic acid).

Animals↗
PubMed1979

Absence of the major dense line in myelin of the mutant mouse "shiverer".

The myelin of the central nervous system (CNS) of the mutant mouse Shiverer is characterized by the absence of the major dense line (MDL). The intraperiod line, as seen in conventional electron micrographs and in freeze-fractured replicas, appears normal. Peripheral myelin, as seen in ventral and dorsal roots of spinal cord, is unaffected by the mutation. During the period of active myelination, the cytoplasm of most oligodendrocytes (ODs) is packed with electron-lucent vacuoles in continuity with the Golgi apparatus and with bundles of microtubules. It is concluded that a metabolic pathway possibly involving the Golgi apparatus, and contributing to the formation of the MDL is selectively affected in this mutant.

Animals↗
PubMed1979

Immunochemical studies of myelin basic protein in shiverer mouse devoid of major dense line of myelin.

The myelin-deficient mutant Shiverer (Shi/Shi) lacks basic protein (MBP) in the myelin of its central nervous system (CNS). Less than 3% of the normal content in MBP is present in a brain extract of Shi/Shi as determined by radioimmunoassay. Indirect immunofluorescence is negative when using specific anti-MBP serum. The importance of Shi/Shi (as compared to other hypomelinating mutants) stems from the specificity of this genetic lesion, i.e. the lack of basic protein.

Animals↗
PubMed1979

Lipid composition of sciatic nerve from dysmyelinating trembler mouse.

The amounts and the distribution of the various lipids were studied in the sciatic nerves from normal and trembler mice. When compared to the normal, the total lipidic amount was reduced by 66% in the trembler mouse, and each class of lipid was decreased nearly the same way, except for the cholesterol esters the value of which increased five times. The level of each individual phospholipid was decreased, phosphatidylcholine being the least affected and phosphatidylserine the most altered.

Animals↗
PubMed1979

Infantile form of so-called neuronal ceroid lipofuscinosis: lipid biochemical studies, fatty acid analysis of cerebroside sulfatides and sphingomyelin, myelin density profile and lipid composition.

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.

Atrophy↗
PubMed1978

Distribution of radioactivity in myelin lipids following subcutaneous injection of [14C]stearate.

Blood fatty acids are an important parameter for the synthesis of brain myelin as exogenous stearic acid is needed: after subcutaneous injection to 18-day-old mice this labelled stearic acid is transported into brain myelin and incorporated into its lipids. However the acid is partly metabolized in the brain by elongation (thus providing very long chain fatty acids, mainly lignoceric acid) or by degradation to acetate units (utilized for synthesis of medium chain fatty acids as palmitic acid, and cholesterol). These metabolites are further incorporated into myelin lipids. The myelin lipid radioactivity increases up to 3 days; most of the activity is found in phospholipids; their fatty acids are labelled in saturated as well as in polyunsaturated homologues but sphingolipids, especially cerebrosides, contain also large amounts of radioactivity (which is mainly found in very long chain fatty acids, almost all in lignoceric acid). The occurrence of unesterified fatty acids must be pointed out, these molecules unlike other lipids, are found in constant amount (expressed in radioactivity per mg myelin lipid).

Animals↗
PubMed1978

[Use of a zonal rotor for demonstrating that human myelin is formed by a continuum of particles of different densities].

Human myelin isolated from frozen brain consists of a continuum of particles as shown by sucrose continuous gradient (between 0,4 and 0,85 M) on zonal rotor. This was determined by measuring the O. D. at 260 and 280 millimicron, the protein concentration by Lowry method and sucrose concentration by polarimetry in 60 fractions. Most of the material is concentrated between 20-23% sucrose, the maximum being found at 21.5% (0.63 M). The fractions are dialyzed for 62 hrs. to remove the sucrose and the pellet obtained after centrifugation shows that the protein concentration increases from the ligher fraction to the heavier.

Brain Chemistry↗
PubMed1978

Incorporation of stearic acid into brain lipids in the developing brain: blood-brain relationships during 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.

Age Factors↗
PubMed1978

Pelizaeus-Merzbacher disease: biochemical analysis of isolated myelin (electron-microscopy; protein, lipid and unsubstituted fatty acids analysis).

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.

Brain Chemistry↗
PubMed1978

Is there a blood-brain relationship for saturated fatty acids during development?

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.

Animals↗