Brain lipids of a case of juvenile Niemann-Pick disease

—Lipids of frontal lobe grey and white matter were examined in parallel from a normal and a diseased child (M. Niemann-Pick), both nine years of age. In the grey matter of the pathological case the following changes, although small, were found: a slight increase in all phospholipids and decreased values for nervonic acid in cerebrosides and for hydroxy fatty acids in sulphatides. White matter seemed much more affected by the disease: water content was about 6 per cent higher which corresponds to an approx. 20 per cent loss of dry substance compared with the normal brain. Further increases were observed in ‘ganglioside’ fraction and in all phosphatides. Cerebroside and sulphatide levels appeared decreased owing to destruction of myelin. In all of the glycerophosphatides oleic acid portions were lowered whereas in sphingolipids mainly nervonic acid values were reduced. Aldehyde content of both tissues seemed lowered in the disease, however, changes in composition were observed only in white matter, where the stearaldehyde portion of ethanolamine glycerophospholipid increased at the expense of palmitaldehyde and oleinaldehyde.     

Differential Grey Matter Changes in Sensorimotor Cortex Related to Exceptional Fine Motor Skills

Functional changes in sensorimotor representation occur in response to use and lesion throughout life. Emerging evidence suggests that functional changes are paralleled by respective macroscopic structural changes. In the present study we used voxel-based morphometry to investigate sensorimotor cortex in subjects with congenitally malformed upper extremities. We expected increased or decreased grey matter to parallel the enlarged or reduced functional representations we reported previously. More specifically, we expected decreased grey matter values in lateral sensorimotor cortex related to compromised hand function and increased grey matter values in medial sensorimotor cortex due to compensatory foot use. We found a medial cluster of grey matter increase in subjects with frequent, hand-like compensatory foot use. This increase was predominantly seen for lateral premotor, supplementary motor, and motor areas and only marginally involved somatosensory cortex. Contrary to our expectation, subjects with a reduced number of fingers, who had shown shrinkage of the functional hand representation previously, did not show decreased grey matter values within lateral sensorimotor cortex. Our data suggest that functional plastic changes in sensorimotor cortex can be associated with increases in grey matter but may also occur in otherwise macroscopically normal appearing grey matter volumes. Furthermore, macroscopic structural changes in motor and premotor areas may be observed without respective changes in somatosensory cortex.     

Concentration and fatty acid composition of cholesteryl esters of normal human brain

Abstract— —Cholesteryl esters were isolated from the cerebral cortex and white matter of human brains at different ages, and their concentration and composition determined. The esters were separated from other lipids by chromatography on silicic acid and finally purified by TLC. The fatty acids were converted to the methyl esters by alkaline trans-methylation and analysed by GLC. A TLC method was elaborated for quantitative determination of small amounts of cholesteryl esters in the presence of free cholesterol. The concentration of cholesteryl esters was only 0·1–0·2 per cent of the total cholesterol content of cerebral tissue in older children and adults. During early myelination the concentration was many times greater, especially in the white matter but it never exceeded 2 per cent of the total cholesterol in any subject. The major fatty acids of human brain cholesteryl esters were oleic, palmitic, palmitoleic and arachidonic acid. After completion of myelination, arachidonic acid constituted the major fatty acid. There were fairly small differences in the fatty acid pattern of the cholesteryl esters between grey and white matter, but the concentration of polyunsaturated fatty acids was larger in the grey matter. Cholesteryl esters appear to play an important role in the metabolism of the phosphoglyceride fatty acids in cerebral tissue.     

Positional Distribution of Acyl and Alk-1-enyl Groups in Grey and White Matter Ethanolamine and Choline Phosphoglycerides of a Marsupial, the Koala (Phascolarctos cinereus)

The major phosphoglycerides in grey and white matter from the brain of the koala have been separated and examined. The major polyunsaturated fatty acids present in both the diacyl- and alk-1-enyl acylglycerophosphorylethanolamines from grey matter were 22:6 omega 3, 20:4 omega 6, and 22:4 omega 6. In both grey and white matter, 22:6 omega 3 and 20:4 omega 6 were concentrated in the 2-position of diacylglycerophosphorylethanolamines and 22:4 omega 6 in the 2-position of alk-1-enylacylglycerophosphorylethanolamines; polyunsaturated fatty acid levels were higher in diacylglycerophosphorylethanolamines. Ethanolamine phosphoglyceride fractions from grey matter were enriched in polyunsaturated fatty acids compared with those from white matter. The acyl groups 18:0, 18:1, and 16:0 and their alk-1-enyl analogues were prominent in grey and white matter ethanolamine phosphoglycerides; 18:1 was dominant in white matter alk-1-enylacylglycerophosphorylethanolamines. The plasmalogen composition of ethanolamine phosphoglycerides was 55% in grey matter and 76% in white matter. Choline phosphoglycerides contained negligible plasmalogen and low polyunsaturated fatty acid levels. Diacylglycerophosphorylcholine was characterized by high levels of 16:0 and 18:1. Similar acyl group distributions were estimated in the 1-position in both grey and white matter, 16:0 being present at greater than 50%. The presence of the molecular species 18:0/22:6 omega 3 was indicated in grey matter diacylglycerophosphorylethanolamine, 18:1/18:1 in white matter alk-1-enylcylglycerophosphorylethanolamine, and 16:0/18:1 in white matter diacylglycerophosphorylcholine.     

COMPARISON OF THE FATTY ACIDS OF LIPIDS OF SUBCELLULAR BRAIN FRACTIONS

Abstract— Rat brain grey and white matter were fractionated to yield myelin, nerve terminal, synaptic vesicle, nerve terminal 'ghost', and microsomal fractions of white and grey matter. Ester-type glycolipids were found in all fractions except myelin, while cerebrosides occurred in significant concentrations only in myelin and white microsomes. Comparison of the fatty acid profile of the ethanolamine- and serine-containing phospholipids showed marked differences between myelin and the particles from grey matter, while the microsomes of white matter were of intermediate composition. Docosahexaenoic acid, a minor acid in myelin, was a major fatty acid in microsomes of grey and white matter. The fatty acid composition of sphingomyelin was distinctly different in the fractions derived from grey and white matter, clustering about stearate and nervonate in the latter, but only about stearate in the grey. Marked differences in the positional distribution of fatty acids were seen within phosphatidyl choline from myelin and nerve terminals. Ribonucleic acid was found in nerve terminal and synaptic vesicle fractions. The sphingosine found in the ganglioside from microsomes of both grey and white matter was similar with respect to distribution of the C₁₈ and C₂₀ homologues.
The possibility is discussed that microsomes furnish characteristic lipids for the synthesis or renewal of specific membranes, and that these lipids are accumulated somewhat before being released.     

Regulation of fatty acid synthesis and Δ9-desaturation in senescence of human fibroblasts

AimsNormal human cells in culture progressively lose their capacity for replication, ending in an irreversible arrested state known as replicative senescence. Senescence has been functionally associated to the process of organismal ageing and is also considered a major tumor-suppressing mechanism. Although a great deal of knowledge has uncovered many of the molecular aspects of senescence, little is known about the regulation of lipid synthesis, particularly the biosynthesis and Δ9-desaturation of fatty acids, during the senescence process.Main methodsBy using immunoblotting and metabolic radiolabeling, we determined the senescence-associated changes in major lipogenic pathways.Key findingsThe levels of fatty acid synthase and stearoyl-CoA desaturase-1 and, consequently, the formation of monounsaturated fatty acids, were notably decreased in senescent cells when compared to proliferating (young) fibroblasts. Moreover, we detected a reduction in the de novo synthesis of phospholipids with a concomitant increase in the formation of cholesterol in senescent cells compared to young fibroblasts. Finally, it was found that exogenous fatty acids were preferentially incorporated into the triacylglycerol pool of senescent cells.SignificanceThis set of observations is the first demonstration of a profound modification in lipid metabolism, particularly fatty acid biosynthesis and desaturation, caused by the senescence process and contributes to the increasing body of evidence linking de novo lipogenesis with cellular proliferation.     

The regulation of fatty acid metabolism and other lipid compounds in ruminant animals

The review deals with peculiarities of molecular mechanisms of metabolism regulation of fatty acids and other lipid components in preruminant and ruminant animals (i.e. before and after formation of the functioning of the mixed microbial population in the rumen). A characteristic of possible biosynthesis regulation processes, transformation, transport, utilization and catabolism of fatty acids with different molecular masses and peculiarities and of triacylglycerols and other lipid substances in the liver compartments, skeletal and heart muscle cells has been shown. Peculiarities of intracellular changes in metabolism of fatty acids and apolipoprotein B in the liver of neonatal calves under development of alimentary enteropathology have been considered. Main factors in the mechanism of regulation of intracellular metabolism of fatty acids and lipid substances have been defined.     

Phospholipids and fatty acids in human brain tumors.

Phospholipid and fatty acid composition of human brain tumors is presented. The white matter contains a greater amount of phosphatidylinositol and a very low level of lysophosphoglycerides, as compared to the grey matter. Glioma and meningioma tumors contain a greater amount of phosphatidylinositol, sphingomyelin, and lysophosphoglycerides, as compared to normal cortex tissue. A significant rise in oleic, linoleic and arachidonic acid content in tumor tissue was observed. It is suggested, that changes in lipid composition, may play a role in structural and functional membrane perturbations in neoplastic cells.     

The role of lipid components of microsomal membranes of hepatocytes of the central Asian turtle in the actualization of radiation injuries

Phase changes in the content of biomembrane lipids and in the rate of their peroxidation were observed in liver microsomes of Testudo horsfieldi irradiated with a dose of 129.10(-1) C/kg. It is suggested that the decrease in the formation of peroxidation products of a diene series at the initial stage of radiation sickness are conditioned by the decrease in the activity of the key enzyme systems which regulate biosynthesis of polyunsaturated fatty acids, while the increase in the sphingomyelin level activates the lipid-dependent enzymes which repair the injured membranes.     

Polyunsaturated fatty acid biosynthesis from [1-14C]20:3 n-6 acid in rat cultured Sertoli cells. Linoleic acid effect

Primary culture is a suitable system to study lipid metabolism and polyunsaturated fatty acid biosynthesis. Sertoli cell-enriched preparations were used to determine the fatty acid composition after 5 and 7 days in culture (serum free) as well as the uptake and metabolism of [1-14C]eicosa-8,11,14-trienoic acid. The addition of unlabeled linoleic acid (0.2 and 2.0 microg/ml) was also evaluated. Fatty acid methyl esters derived from cellular lipids were analyzed by gas liquid chromatography and radiochromatography. After 5 days in culture, cells had significantly less 18:2, 20:4, 22:5 and 24:5 and more 18:3, 20:3, 22:4 and 24:4 n-6 fatty acids than non-cultured cells. On day 7, an additional increment in 22:4 n-6 and a decrease in linoleic, gamma-linoleic and 24:4 n-6 fatty acids were observed. The presence of linoleic acid (low dose) produced a significant decrease in saturated and monounsaturated acids and an increase in 18:2, 20:4 and 22:5 n-6 fatty acids. At a high concentration almost all fatty acids belonging to 18:2 n-6 increased significantly. The drop in 20:4 n-6/20:3 n-6 ratio was considered as an indirect evidence of a Delta 5 desaturase activity depression. This assumption was corroborated by studying the transformation of [1-14C]eicosa-8,11,14-trienoic acid into 20:4, 22:4, 22:5, 24:4 and 24:5 n-6 fatty acids. We conclude that Sertoli cells after 7 days in culture evidenced changes in the fatty acid profile similar to those described under fat deprivation. The addition of linoleic acid reverted this pattern and indicated that the Delta 5 desaturase activity is a limiting step in the polyunsaturated fatty acid biosynthesis.     

Morphine-induced changes in prostaglandin precursor fatty acids in phospholipids of mouse liver and serum.

Changes in phosphoglyceride acyl groups known to be the precursor fatty acids of prostaglandis were observed in mouse liver and serum with respect to morphine administration. The changes correlated with a significant decrease in the proportion of dihomo-γ-linolenic acid, 20:3(n-6), and an increase in arachidonic acid, 20:4(n-6) in the phosphoglycerides of liver and serum. At 12–24 hrs after morphine pellet implantation, the diacyl-$\text{sn}$-glycero-3-phosphocholines in liver and serum showed a 50% decrease in 20:3(n-6)/20:4(n-6) ratio as compared to controls. During this period, the lysolecithin in serum showed an increase in the proportion of 16:0 and a decrease in the proportion of unsaturated acyl groups. Most changes returned gradually to control values by 9 days although new morphine pellets were implanted into the mice every third day. Since fatty acids are released from membrane phospholipids prior to prostaglandin biosynthesis, the morphine-induced changes in phosphoglyceride acyl groups is reflective of an altered prostaglandin metabolism in liver and serum.     

Lipid Investigation of Central and Peripheral Nervous System in Connatal Pelizaeus-Merzbacher's Disease

Abstract: Brain grey and white matter of a case of Pelizaeus-Merzbacher disease (connatal type Seitelberger) of a 19-month-old boy were analysed with respect to lipids. Cerebrosides and sulfatides were totally absent in the pathological brain. In comparison to control, differences in gangliosides could be detected in grey and white manner. C_18:1, fatty acids were markedly reduced in the main glycerophospholipids of white matter. In sphingomyelin of cortex and white matter 90% of fatty acids were C_18:0; longer chains were absent. In contrast: PNS (nervus fernoralis) lipids contained the main galactolipids. However, these a s well as all other lipid classes showed a 20% reduction compared with values obtained from nervus femoralis of an infant of the same age. The fatty acid patterns of all lipid classes were determined. The only marked deviations from normal were observed in the C₂₄-chains of cere-brosides and sulfatides. The formalin-fixed brain of an older brother (same disease) was analysed only with respect to glycolipids: neither cerebrosides nor sulfatides could be detected.     

Distribution of acid and alkaline deoxyribonucleases in white and grey matter regions of growing and aging chick brain

The activities of acid and alkaline deoxyribonucleases in the white and grey matter areas of growing and old chick cerebrum were measured. Two marker enzymes for glial cells, butyrylcholinesterase and carbonic anhydrase were also measured in these regions. Higher specific activities of both butyrylcholinesterase and carbonic anhydrase were found in the white matter region at all the stages studied. Acid and alkaline deoxyribonuclease activities were observed in both white and grey matter. The decrease in the specific activity of acid deoxyribonuclease with advancement of age was more pronounced as compared to the alkaline deoxyribonuclease Marked reduction in total acid deoxyribonuclease activity in white matter, beyond the age of 130 days, was observed. On the other hand, total alkaline deoxyribonuclease activity in both white and grey matter continued to increase with age Further, the activity per mg of DNA also increased in white matter of the old brain. These results indirectly suggest a continued role for alkaline deoxyribonuclease in glial cells formed at a later age.     

Utilization of multiple substrates by butyrate kinase from Listeria monocytogenes

Listeria monocytogenes, the causative agent of listeriosis, can build up to dangerous levels in refrigerated foods potentially leading to expensive product recalls. An important aspect of the bacterium's growth at low temperatures is its ability to increase the branched-chain fatty acid anteiso C15:0 content of its membrane at lower growth temperatures, which imparts greater membrane fluidity. Mutants in the branched-chain α-keto dehydrogenase (bkd) complex are deficient in branched-chain fatty acids (BCFAs,) but these can be restored by feeding C4 and C5 branched-chain carboxylic acids (BCCAs). This suggests the presence of an alternate pathway for production of acyl CoA precursors for fatty acid biosynthesis. We hypothesize that the alternate pathway is composed of butyrate kinase (buk) and phosphotransbutyrylase (ptb) encoded in the bkd complex which produce acyl CoA products by their sequential action through the metabolism of carboxylic acids. We determined the steady state kinetics of recombinant His-tagged Buk using 11 different straight-chain and BCCA substrates in the acyl phosphate forming direction. Buk demonstrated highest catalytic efficiency with pentanoate as the substrate. Low product formation observed with acetate (C2) and hexanoate (C6) as the substrates indicates that Buk is not involved in either acetate metabolism or long chain carboxylic acid activation. We were also able to show that Buk catalysis occurs through a ternary complex intermediate. Additionally, Buk demonstrates a strong preference for BCCAs at low temperatures. These results indicate that Buk may be involved in the activation and assimilation of exogenous carboxylic acids for membrane fatty acid biosynthesis.     

Regulation of enzyme turnover during tissue differention. Studies on the effects of hormones on the turnover of fatty acid synthetase in rabbit mammary gland in organ culture.

1. Explants of mammary gland from mid-pregnant rabbits were cultured with insulin, prolactin and cortisol. 2. Antibodies raised to fatty acid synthetase were used to measure the amount as well as the rate of synthesis and the rate of degradation of the enzyme in the explants over defined periods in organ culture. These measurements were also made after the hormones had been removed from the culture medium. The changes which occur in the activity of fatty acid synthetase are due to changes in the amount of the enzyme present. They are not due to activation or inactivation of the enzyme. 3. The rate of lipogenesis (measured from [1-14C]acetate) in the explants during culture varies independently of the amount of fatty acid synthetase both in the presence and after removal of the hormones. Hence the amount of fatty acid synthetase does not limit lipogenesis. The proportion of medium-chain fatty acids C8:0 and C10:0 (which are characteristic of rabbit milk) synthesized by the explants in the presence of hormones increases at about the same rate as the amount of fatty acid synthetase present. However, when hormones are removed from the medium the proportion of these acids synthesized declines as rapidly as the rate of lipogenesis and not as the amount of fatty acid synthetase presen. 4. The rates of synthesis of fatty acid synthetase and of the total particulate-free supernatant protein in the explants were compared by measuring the incorporation of L-[U-14C]leucine into the protein of the explants. These rates increase by 5-fold and 3.6-fold respectively when explants are cultured with hormones, and they then reach approximately constant rates. When the hormones are removed there is a rapid fall in the rate of synthesis of fatty acid synthetase and of the total particulate-free supernatant protein to values which are similar to those obtained with freshly prepared explanted tissue. 5. In unstimulated explants fatty acid synthetase appears to be degraded with a half-life of 15-21h. During the hormonally stimulated differentiation of the tissue the rate of degradation of the enzyme is considerably decreased or is switched off completely. After the amount of fatty acid synthetase has increased to a maximum the enzyme complex is again degraded with a half-life of 23-29h. The removal of hormones after the explants have been hormonally stimulated for different times results in an increase in the rate of degradation of fatty acid synthetase. However, this increase only occurs if degradation was previously proceeding at a considerably decreased rate. The degradation of the total particulate-free supernatant protein continues throughout the period of differentiation of the explant tissue in culture. It appears to be somewhat decreased during the period of rapid maturation of the tissue during culture.     

Incorporation of acetate-1-14C into lipids by the perfused liver of normal, X-irradiated, or partially hepatectomized rats

In order to study lipid metabolism in the liver without interference due to transport from and to the liver the isolated livers of normal, X-irradiated, and partially hepatectomized rats were perfused with acetate-1-(14)C and the distribution of radioactivity in total lipids, total fatty acids, individual lipids, and fatty acids of individual lipids was determined. In X-irradiated animals, an increased incorporation of acetate into many lipids, particularly into cholesterol, was observed. Lipids in the liver of the partially hepatectomized rats exhibited a marked increase in triglyceride content together with a decreased rate of incorporation into all but the phospholipid fractions. It is concluded that the increase usually observed in lipid pontent of the regenerating liver is due to the changes in transcort rather than to changes in synthesis. The changes observed in irradiated liver could be the result of alterations in the metabolism of precursors common to most lipids.     

Chemical compositions of brain and myelin in two patients with multiple sulphatase deficiency (a variant form of metachromatic leukodystrophy)

The lipid composition of the brain, including myelin, was studied in detail in two cases with a variant form of metachromatic leukodystrophy (multiple sulphatase deficiency type). In the white matter, the sulphatide concentration was 3-4 times higher than the normal level in both cases. There was a significant accumulation of cholesterol sulphate in the brain, liver and kidney of both cases. The ganglioside pattern in the grey and white matter was abnormal, with a higher proportion of GM3, GM2 and GD3-gangliosides. Non-lipid hexosamine contents were increased 1.5-2 times in brain, 8-10 times in liver and 2-3 times in kidney. Increased amounts of glucocerobroside, ceramide lactoside and ceramide trihexoside were present in grey and white matter of both cases. Recovery of purified myelin from two patients' brains was much less than from control (1-2% in case 1 and 20-30% in case 2). The lipid composition of myelin was almost normal except for a higher proportion of sulphatide, with a decreased amount of cerebroside. The fatty acid compositions of myelin sulphatide and sphingomyelin were almost normal, while non-hydroxy fatty acids of cerebroside contained less long-chain fatty acids, as characterized by a significant increase of C16:0 and C18:0 fatty acids. The myelin polypeptide pattern by SDS-disc gel electrophoresis showed a relative decrease of basic protein and of proteolipid protein. A possible mechanism of myelin loss in MSD is discussed.     

A comparison of the Baker acid Haematein staining of selected regions of rat hypothalamus with the fatty acid composition of their phosphatidyl choline content and their polar lipid fraction as determined by gas liquid chromatography

Synopsis Application of Baker's acid Haematein test for the histochemical detection of phospholipids to rat hypothalamus reveals striking colour differences between white and grey matter. It was found previously that these differences could not be attributed to corresponding differences in the acid Haematein-positive lipid content in various regions of the hypothalamus. As the staining reaction might depend on the degree of unsaturation of lipids, the fatty acid compositions of phosphatidyl choline and the polar lipid fraction from the optic chiasma and some regions of rat hypothalamus were investigated.The polar lipid fraction of the optic chiasma contained relatively more mono-unsaturated and less saturated fatty acids than the polar lipid fractions from the area anterior, and the suprnoptic and paraventricular nuclei of the hypothalamus. The same trend was observed for the fatty acid composition of phosphatidyl choline isolated from these regions. Both the polar lipid fraction and phosphatidyl choline showed a lower content of poly-unsaturated fatty acids in the optic chiasma than in the area anterior. It is argued that the colour differences between myclinated and unmyelinated regions of the hypothalamus demonstrable after application of Baker's acid Haematein test cannot be ascribed merely to corresponding differences in the amounts of unsaturated lipids in these regions. According to the author the particular structure of myelin might be held responsible for the stronger staining of white matter compared with grey matter.