Fatty acid composition of myelin isolated from the brain of a patient with cellular deficiency of co-enzyme forms of vitamin B12

Nutritional peripheral neuropathies

Nutritional peripheral neuropathies are a global problem, heavily influenced by geopolitical, cultural and socioeconomic factors. Peripheral neuropathy occurs most frequently secondary to B-vitamin deficiencies, which is suspected to increase in years to come due to the popularity of vegan and vegetarian diets and increased use of bariatric surgery.This review will focus on the common B-vitamins for which a causal link to peripheral neuropathy is more established (vitamins B1, B2, B6, B9 and B12). We will review the historical human and animal data on which much of the clinical descriptions of vitamin deficiencies are based and summarise current available tools for accurately diagnosing a nutritional deficiency. We will also review recently described genetic diseases due to pathogenic variants in genes involved in B-vitamin metabolism that have helped to inform the phenotypes and potential causality of certain B-vitamins in peripheral neuropathy (B2 and B9).Endemic outbreaks of peripheral neuropathy over the last two centuries have been linked to food shortages and nutritional deficiency. These include outbreaks in Jamaican sugar plantation workers in the nineteenth century (Strachan's syndrome), World War two prisoners of war, Cuban endemic neuropathy and also Tanzanian endemic optic neuropathy, which remains a significant public health burden today. An improved understanding of lack of which vitamins cause peripheral neuropathy and how to identify specific deficiencies may lead to prevention of significant and irreversible disability in vulnerable populations.

Monomethyl branched-chain fatty acids-a pearl dropped in the ocean

As an emerging group of bioactive fatty acids, monomethyl branched-chain fatty acids (mmBCFAs) have sparked the interest of many researchers both domestically and internationally. In addition to documenting the importance of mmBCFAs for growth and development, there is increasing evidence that mmBCFAs are highly correlated with obesity and insulin resistance. According to previous pharmacological investigations, mmBCFAs also exhibit anti-inflammatory effects and anticancer properties. This review summarized the distribution of mmBCFAs, which are widely found in dairy products, ruminants, fish, and fermented foods. Besides, we discuss the biosynthesis pathway in different species and detection methods of mmBCFAs. With the hope to unveil their mechanisms of action, we recapitulated detailed the nutrition and health benefits of mmBCFAs. Furthermore, this study provides a thorough, critical overview of the current state of the art, upcoming difficulties, and trends in mmBCFAs.

Plasma Lipolysis and Changes in Plasma and Cerebrospinal Fluid Signaling Lipids Reveal Abnormal Lipid Metabolism in Chronic Migraine

Background

Lipids are a primary storage form of energy and the source of inflammatory and pain signaling molecules, yet knowledge of their importance in chronic migraine (CM) pathology is incomplete. We aim to determine if plasma and cerebrospinal fluid (CSF) lipid metabolism are associated with CM pathology.

Methods

We obtained plasma and CSF from healthy controls (CT, n = 10) or CM subjects (n = 15) diagnosed using the International Headache Society criteria. We measured unesterified fatty acid (UFA) and esterified fatty acids (EFAs) using gas chromatography-mass spectrometry. Glycerophospholipids (GP) and sphingolipid (SP) levels were determined using LC-MS/MS, and phospholipase A₂ (PLA₂) activity was determined using fluorescent substrates.

Results

Unesterified fatty acid levels were significantly higher in CM plasma but not in CSF. Unesterified levels of five saturated fatty acids (SAFAs), eight monounsaturated fatty acids (MUFAs), five ω-3 polyunsaturated fatty acids (PUFAs), and five ω-6 PUFAs are higher in CM plasma. Esterified levels of three SAFAs, eight MUFAs, five ω-3 PUFAs, and three ω-6 PUFAs, are higher in CM plasma. The ratios C20:4n-6/homo-γ-C20:3n-6 representative of delta-5-desaturases (D5D) and the elongase ratio are lower in esterified and unesterified CM plasma, respectively. In the CSF, the esterified D5D index is lower in CM. While PLA₂ activity was similar, the plasma UFA to EFA ratio is higher in CM. Of all plasma GP/SPs detected, only ceramide levels are lower (p = 0.0003) in CM (0.26 ± 0.07%) compared to CT (0.48 ± 0.06%). The GP/SP proportion of platelet-activating factor (PAF) is significantly lower in CM CSF.

Conclusions

Plasma and CSF lipid changes are consistent with abnormal lipid metabolism in CM. Since plasma UFAs correspond to diet or adipose tissue levels, higher plasma fatty acids and UFA/EFA ratios suggest enhanced adipose lipolysis in CM. Differences in plasma and CSF desaturases and elongases suggest altered lipid metabolism in CM. A lower plasma ceramide level suggests reduced de novo synthesis or reduced sphingomyelin hydrolysis. Changes in CSF PAF suggest differences in brain lipid signaling pathways in CM. Together, this pilot study shows lipid metabolic abnormality in CM corresponding to altered energy homeostasis. We propose that controlling plasma lipolysis, desaturases, elongases, and lipid signaling pathways may relieve CM symptoms.

The synthesis of branched-chain fatty acids is limited by enzymatic decarboxylation of ethyl- and methylmalonyl-CoA

Most fatty acids (FAs) are straight chains and are synthesized by fatty acid synthase (FASN) using acetyl-CoA and malonyl-CoA units. Yet, FASN is known to be promiscuous as it may use methylmalonyl-CoA instead of malonyl-CoA and thereby introduce methyl-branches. We have recently found that the cytosolic enzyme ECHDC1 degrades ethylmalonyl-CoA and methylmalonyl-CoA, which presumably result from promiscuous reactions catalyzed by acetyl-CoA carboxylase on butyryl- and propionyl-CoA. Here, we tested the hypothesis that ECHDC1 is a metabolite repair enzyme that serves to prevent the formation of methyl- or ethyl-branched FAs by FASN. Using the purified enzyme, we found that FASN can incorporate not only methylmalonyl-CoA but also ethylmalonyl-CoA, producing methyl- or ethyl-branched FAs. Using a combination of gas-chromatography and liquid chromatography coupled to mass spectrometry, we observed that inactivation of ECHDC1 in adipocytes led to an increase in several methyl-branched FAs (present in different lipid classes), while its overexpression reduced them below wild-type levels. In contrast, the formation of ethyl-branched FAs was observed almost exclusively in ECHDC1 knockout cells, indicating that ECHDC1 and the low activity of FASN toward ethylmalonyl-CoA efficiently prevent their formation. We conclude that ECHDC1 performs a typical metabolite repair function by destroying methyl- and ethylmalonyl-CoA. This reduces the formation of methyl-branched FAs and prevents the formation of ethyl-branched FAs by FASN. The identification of ECHDC1 as a key modulator of the abundance of methyl-branched FAs opens the way to investigate their function.

Impact of inhaled nitric oxide on the sulfatide profile of neonatal rat brain studied by TOF-SIMS imaging

Despite advances in neonatal intensive care leading to an increased survival rate in preterm infants, brain lesions and subsequent neurological handicaps following preterm birth remain a critical issue. To prevent brain injury and/or enhance repair, one of the most promising therapies investigated in preclinical models is inhaled nitric oxide (iNO). We have assessed the effect of this therapy on brain lipid content in air- and iNO-exposed rat pups by mass spectrometry imaging using a time-of-flight secondary ion mass spectrometry (TOF-SIMS) method. This technique was used to map the variations in lipid composition of the rat brain and, particularly, of the white matter. Triplicate analysis showed a significant increase of sulfatides (25%–50%) in the white matter on Day 10 of life in iNO-exposed animals from Day 0–7 of life. These robust, repeatable and semi-quantitative data demonstrate a potent effect of iNO at the molecular level.

A Novel Phosphatidylcholine Which Contains Pentadecanoic Acid at sn-1 and Docosahexaenoic Acid at sn-2 in Schizochytrium sp. F26-b

Docosahexaenoic acid (DHA, 22:6n-3)-containing phospholipids are a ubiquitous component of the central nervous system and retina, however their physiological and pharmacological functions have not been fully elucidated. Here, we report a novel DHA-containing phosphatidylcholine (PC) in a marine single cell eukaryote, Schizochytrium sp. F26-b. Interestingly, 31.8% of all the fatty acid in F26-b is DHA, which is incorporated into triacylglycerols and various phospholipids. In phospholipids, DHA was found to make up about 50% of total fatty acid. To identify phospholipid species containing DHA, the fraction of phospholipids from strain F26-b was subjected to normal phase high-performance liquid chromatography (HPLC). It was found that DHA was incorporated into PC, lyso-PC, phosphatidylethanolamine, and phosphatidylinositol. The major DHA-containing phospholipid was PC in which 32.5% of the fatty acid was DHA. The structure of PC was analyzed further by phospholipase A2 treatment, fast atom bombardment mass spectrometry, and 1H- and 13C-NMR after purification of the PC with reverse phase HPLC. Collectively, it was clarified that the major PC contains pentadecanoic acid (C15:0) at sn-1 and DHA at sn-2; the systematic name of this novel PC is therefore "1-pentadecanoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine."

Monomethyl branched-chain fatty acids play an essential role in Caenorhabditis elegans development

Monomethyl branched-chain fatty acids (mmBCFAs) are commonly found in many organisms from bacteria to mammals. In humans, they have been detected in skin, brain, blood, and cancer cells. Despite a broad distribution, mmBCFAs remain exotic in eukaryotes, where their origin and physiological roles are not understood. Here we report our study of the function and regulation of mmBCFAs in Caenorhabditis elegans, combining genetics, gas chromatography, and DNA microarray analysis. We show that C. elegans synthesizes mmBCFAs de novo and utilizes the long-chain fatty acid elongation enzymes ELO-5 and ELO-6 to produce two mmBCFAs, C15ISO and C17ISO. These mmBCFAs are essential for C. elegans growth and development, as suppression of their biosynthesis results in a growth arrest at the first larval stage. The arrest is reversible and can be overcome by feeding the arrested animals with mmBCFA supplements. We show not only that the levels of C15ISO and C17ISO affect the expression of several genes, but also that the activities of some of these genes affect biosynthesis of mmBCFAs, suggesting a potential feedback regulation. One of the genes, lpd-1, encodes a homolog of a mammalian sterol regulatory element-binding protein (SREBP 1c). We present results suggesting that elo-5 and elo-6 may be transcriptional targets of LPD-1. This study exposes unexpected and crucial physiological functions of C15ISO and C17ISO in C. elegans and suggests a potentially important role for mmBCFAs in other eukaryotes.

The cellular localization of malonyl-coenzyme A decarboxylase in rat brain

Malonyl-coenzyme A (CoA) decarboxylase (E.C.4.1.1.9) activity in brain is low but steadily increases after birth. The main physiological role of this mitochondrial enzyme is thought to be the stabilization of malonyl-CoA levels which change very little with brain growth. In an effort to visualize malonyl-CoA decarboxylase by immunocytochemistry, and to determine its developmental changes, the enzyme was purified by an efficient small-scale procedure involving isolation of mitochondria, extraction at high ionic strength, isoelectric focusing, column chromatography, and preparative polyacrylamide gel electrophoresis. The enzyme from brain showed the same apparent molecular weight (160 kDa) and was immunoreactive with antisera raised against malonyl-CoA decarboxylase from liver. Immunocytochemistry revealed early and extensive labeling of hepatocytes in rat liver but only delayed visualization in the brain. Most nerve cells of the cerebral cortex and many microglia were stained but the neurons of the cerebellar cortex did not become reactive. Golgi epithelial cells and their processes, the Bergmann glia, also showed reaction product.

Cobalt-vitamin B12 deficiency causes accumulation of odd-numbered, branched-chain fatty acids in the tissues of sheep

Nine 5-month-old lambs were randomly allocated to two groups and were fed on either a Co-deficient whole-barley diet (n5), or the same diet supplemented with Co (n4). The lambs were fed on their respective diets for 28 weeks. Plasma vitamin B12 concentrations fell below the lower limit of normality after 6 weeks, and plasma methylmalonic acid (MMA) concentrations rose above the upper limit of normality after 10 weeks. However, plasma MMA concentrations fell to near normal levels towards the end of the experiment suggesting that diagnosis of more severe Co deficiency based on determination of plasma MMA concentrations may be of limited value. Analysis of tissue samples collected at slaughter revealed a marked reduction in the vitamin B12 concentration and the activity of methylmalonyl-CoA mutase (EC5.4.99.2) in the tissues taken from the Co-deficient sheep, by comparison with the controls. Although tissue concentrations of MMA in the Co-deficient animals were not significantly different from those of the controls, we did detect increased concentrations of branched-chain fatty acids. This suggested that misincorporation of MMA, but not propionic acid, into fatty acids had occurred. The Co-deficient lambs did not develop any neurological signs, suggesting that accumulation of branched-chain fatty acids may not be involved in the development of neurological lesions.

Stabilization of egg phosphatidylcholine liposomes by the insertion of sulfatide

The characteristic effects of sulfatide and its derivatives on the stability of small unilamellar vesicles of egg phosphatidylcholine liposomes in phosphate-buffered saline were investigated by measuring the leakage of carboxyfluorescein that had been entrapped in these vesicles. We found that both the sulfate group and a long acyl chain, such as lignoceric acid, of the sulfatide are essential for the stabilization. The sulfatide derivatives that contain a somewhat shorter acyl chain such as stearic acid had no effect to suppress the leakage of carboxyfluorescein. The galactose residue of sulfatide is not essential to suppress the leakage. 1H-NMR study using a paramagnetic shift reagent demonstrated that the distribution of phosphatidylcholine in the vesicles containing sulfatide is homogeneous, which seems to contribute to the stability of the membrane.

Maternal vegan diet causing a serious infantile neurological disorder due to vitamin B12 deficiency

We present a 9-month-old exclusively breast-fed baby of a strict vegetarian mother who had excluded all animal proteins from her diet. The patient's symptoms included dystrophy, weakness, muscular atrophy, loss of tendon reflexes, psychomotor regression and haematological abnormalities. Biochemical investigations revealed severe methylmalonic aciduria and homocystinuria in the patient, slight methylmalonic aciduria in the mother and low concentrations of serum vitamin B12 in both patient and mother.

The fruit bat as an experimental model of the neuropathy of cobalamin deficiency

The fruit bat provides a unique small mammal model of the neurological changes associated with cobalamin deficiency. Work with this model has shown that methionine moderates the development of the neurological impairment. This action does not appear to be via the methyl donor S-adenosylmethionine, but its role in the provision of formate is not excluded. Furthermore, methylation reactions in the nervous system are not impaired in severe cobalamin deficiency, despite low levels of methionine synthetase activity. The accumulation of physiologically inactive analogues of cobalamin also do not appear to be aetiologically important in the neuropathy. Brain folates are minimally affected by severe cobalamin deficiency, although liver folates decrease significantly. Deranged GABA function in the brain may play a role in the symptomatology of cobalamin deficiency. There is some evidence for the hypothesis that deranged fatty acid metabolism in neural tissue contributes to altered membrane structure and hence function. Changes in the properties of membrane proteins may play a contributory role. The biochemical basis of the neuropathy has still to be fully elucidated.

Lipids of nervous tissue: composition and metabolism

As indicated in the Introduction, the many significant developments in the recent past in our knowledge of the lipids of the nervous system have been collated in this article. That there is a sustained interest in this field is evident from the rather long bibliography which is itself selective. Obviously, it is not possible to summarize a review in which the chemistry, distribution and metabolism of a great variety of lipids have been discussed. However, from the progress of research, some general conclusions may be drawn. The period of discovery of new lipids in the nervous system appears to be over. All the major lipid components have been discovered and a great deal is now known about their structure and metabolism. Analytical data on the lipid composition of the CNS are available for a number of species and such data on the major areas of the brain are also at hand but information on the various subregions is meagre. Such investigations may yet provide clues to the role of lipids in brain function. Compared to CNS, information on PNS is less adequate. Further research on PNS would be worthwhile as it is amenable for experimental manipulation and complex mechanisms such as myelination can be investigated in this tissue. There are reports correlating lipid constituents with the increased complexity in the organization of the nervous system during evolution. This line of investigation may prove useful. The basic aim of research on the lipids of the nervous tissue is to unravel their functional significance. Most of the hydrophobic moieties of the nervous tissue lipids are comprised of very long chain, highly unsaturated and in some cases hydroxylated residues, and recent studies have shown that each lipid class contains characteristic molecular species. Their contribution to the properties of neural membranes such as excitability remains to be elucidated. Similarly, a large proportion of the phospholipid molecules in the myelin membrane are ethanolamine plasmalogens and their importance in this membrane is not known. It is firmly established that phosphatidylinositol and possibly polyphosphoinositides are involved with events at the synapse during impulse propagation, but their precise role in molecular terms is not clear. Gangliosides, with their structural complexity and amphipathic nature, have been implicated in a number of biological events which include cellular recognition and acting as adjuncts at receptor sites. More recently, growth promoting and neuritogenic functions have been ascribed to gangliosides. These interesting properties of gangliosides wIll undoubtedly attract greater attention in the future.(ABSTRACT TRUNCATED AT 400 WORDS)

Fatty acid composition of synaptosomes from normal and cobalamin deficient bat brain

1. Synaptosomes were prepared from the brain of cobalamin deficient and cobalamin supplemented fruit bats (Rousettus aegyptiacus) by a floatation method on a discontinuous sucrose gradient. 2. There were no significant differences in fatty acid composition between the deficient and supplemented bats. 3. The odd chain fatty acid 15:0 amounted to 0.2% of the total fatty acids in both groups. 4. We conclude that the fatty acids of synaptosomal lipids are not a factor in the development of neural dysfunction in the cobalamin deficient fruit bat.