Maurice D. Laryea

Homocysteine-betaine interactions in a murine model of 5,10-methylenetetrahydrofolate reductase deficiency

Hyperhomocysteinemia, a proposed risk factor for cardiovascular disease, is also observed in other common disorders. The most frequent genetic cause of hyperhomocysteinemia is a mutated methylenetetrahydrofolate reductase (MTHFR), predominantly when folate status is impaired. MTHFR synthesizes a major methyl donor for homocysteine remethylation to methionine. We administered the alternate choline‐derived methyl donor, betaine, to wild‐type mice and to littermates with mild or severe hyperhomocysteinemia due to hetero‐ or homozygosity for a disruption of the Mthfr gene. On control diets, plasma homocysteine and liver choline metabolite levels were strongly dependent on the Mthfr genotype. Betaine supplementation decreased homocysteine in all three genotypes, restored liver betaine and phosphocholine pools, and prevented severe steatosis in Mthfr‐deficient mice. Increasing betaine intake did not further decrease homocysteine. In humans with cardiovascular disease, we found a significant negative correlation between plasma betaine and homocysteine concentrations. Our results emphasize the strong interrelationship between homocysteine, folate, and choline metabolism. Hyperhomocysteinemic Mthfr‐compromised mice appear to be much more sensitive to changes of choline/betaine intake than do wild‐type animals. Hyperhomocysteinemia, in the range of that associated with folate deficiency or with homozygosity for the 677T MTHFR variant, may be associated with disturbed choline metabolism.

Betaine rescue of an animal model with methylenetetrahydrofolate reductase deficiency

MTHFR (methylenetetrahydrofolate reductase) catalyses the synthesis of 5-methyltetrahydrofolate, the folate derivative utilized in homocysteine remethylation to methionine. A severe deficiency of MTHFR results in hyperhomocysteinaemia and homocystinuria. Betaine supplementation has proven effective in ameliorating the biochemical abnormalities and the clinical course in patients with this deficiency. Mice with a complete knockout of MTHFR serve as a good animal model for homocystinuria; early postnatal death of these mice is common, as with some neonates with low residual MTHFR activity. We attempted to rescue Mthfr-/- mice from postnatal death by betaine supplementation to their mothers throughout pregnancy and lactation. Betaine decreased the mortality of Mthfr-/- mice from 83% to 26% and significantly improved somatic development from postnatal day 1, compared with Mthfr-/- mice from unsupplemented dams. Biochemical evaluations demonstrated higher availability of betaine in suckling pups, decreased accumulation of homocysteine, and decreased flux through the trans-sulphuration pathway in liver and brain of Mthfr-/- pups from betaine-supplemented dams. We observed disturbances in proliferation and differentiation in the cerebellum and hippocampus in the knockout mice; these changes were ameliorated by betaine supplementation. The dramatic effects of betaine on survival and growth, and the partial reversibility of the biochemical and developmental anomalies in the brains of MTHFR-deficient mice, emphasize an important role for choline and betaine depletion in the pathogenesis of homocystinuria due to MTHFR deficiency.

Analysis of the fatty acid composition of erythrocyte phospholipids by a base catalysed transesterification method — prevention of formation of dimethylacetals

A sensitive method for the analysis of the fatty acid composition of erythrocyte phospholipids with capillary column GLC is described. Under the assay conditions (base catalysed transesterification with sodium methoxide), only the fatty acids of the phospholipids are converted to their methylesters. The alkenyl ether chains of the plasmalogens are not transmethylated. This eliminates the need for thin layer chromatography for the separation of dimethylacetals and esterified fatty acids. The method is suitable for the measurement of the fatty acid patterns of erythrocyte phospholipids in small blood samples.

Porcine choroid plexus epithelial cells induce Streptococcus suis bacteriostasis in vitro.

ABSTRACT The involvement of the choroid plexus in host defense during bacterial meningitis is unclear. Aiming to elucidate possible antibacterial mechanisms, we stimulated primary porcine choroid plexus epithelial cells (pCPEC) with proinflammatory cytokines and challenged them with various Streptococcus suis strains. In the supernatant of gamma interferon (IFN-γ)-stimulated pCPEC, streptococcal growth was markedly suppressed. Costimulation with tumor necrosis factor alpha enhanced this bacteriostatic effect, while supplementation of l-tryptophan completely eliminated it. We also demonstrate that an activation of indoleamine 2,3-dioxygenase in the pCPEC seems to be responsible for the IFN-γ-induced bacteriostasis. This supports the hypothesis of an active role of the choroid plexus in host defense against bacterial meningitis.

Age-dependent fatty acid composition of erythrocyte membrane phospholipids in healthy children

SummaryThe fatty-acid composition of red-cell-membrane phospholipids (total phospholipids, phosphatidylcholine, and phosphatidylethanolamine fractions) was determined in 88 apparently healthy children aged 1 to 15 years, 10 cord blood samples, and 6 infants below 1 year of age.The major aim of the study was to determine the normal ranges of fatty-acid proportions, including trans- and odd-numbered fatty acids, for further studies of nutritional and metabolic disorders.The concentrations of most fatty acids of the phospholipids analyzed increased or decreased after birth and assumed adult levels before the second year of life. α-linolenic acid (C18∶3n-3) and trans fatty acids, however, continued to increase with age until late childhood.ZusammenfassungBei insgesamt 88 gesunden Kindern im Alter zwischen 1 und 15 Jahren, 6 Kindern unter einem Jahr und in 10 Nabelschnurblutproben wurde die Fettsäurenzusammensetzung der Phospholipide (Gesamt-Phospholipide, Phosphatidylethanolamin, Phosphatidylcholin) untersucht. Ziel der Arbeit war es, altersabhängige Normbereiche für die prozentuale Fettsäurenverteilung einschlie\lich der Trans-Fettsäuren und der ungeradzahligen Fettsäuren zu erstellen, als Grundlage für weitere Untersuchungen bei Ernährungsstörungen und Stoffwechselkrankheiten. Die untersuchten Phospholipide wiesen besonders im 1. Lebensjahr deutliche Veränderungen in der Fettsäurenverteilung auf. Bis zu Beginn des 2. Lebensjahres bildete sich ein „adultes“ Muster heraus. Lediglich die prozentualen Anteile der α-Linolensäure (18∶3n-3) und die der Trans-Fettsäuren stiegen weiter bis zur zweiten Lebensdekade an.

Composition of foods and dishes commonly consumed in villages of the Gezira area of Sudan.

The water, protein, fat, glucose, fructose, sucrose, lactose, starch and energy contents of the important grains, seeds, legumes, fruits, vegetables and dishes are given. These values may be used for nutritional surveys and for nutritional recommendations in future. The composition of foodstuffs and ready‐to‐eat‐meals of the Gezira area of the Sudan is insufficiently known. Therefore, the main foodstuffs and ready‐to‐eat‐meals have been collected, their recipes described and their composition chemically estimated.

Simultaneous determination of betaine and N,N-dimethylglycine in urine

A method is described for the determination of betaine and its metabolite N,N-dimethylglycine in human urine. The method involves a deamination step and a solid-phase extraction to isolate both substances from urine followed by high performance liquid chromatography (HPLC) separation on a 5-microns SCX column with UV absorbance detection. Limit of detection is about 0.9 micrograms for both substances. Recoveries were > 85%. The method appears to be suitable for monitoring betaine and its metabolite in urine of patients undergoing therapy with betaine.

The fatty acid composition of subcutaneous fat in German adults

SummaryThe fatty acid (FA) composition of subcutaneous fat (SCF) was analyzed in 47 German adults. No influences of sex or age on the FA status of the probands could be detected. SCF consisted mainly of monoenoic fatty acids. Linoleic acid was the major polyunsaturated fatty acid. Linoleic acid metabolites were found in small quantities only. In comparison to the results of studies in the USA and the Netherlands the FA composition of SCF in German probands was characterized by lower levels of linoleic acid and higher contents of palmitic acid. The trans-FA content was similar to that in Dutch women, but lower than in American male probands. However, in evaluating the differences in the FA composition of SCF in different countries, it has to be noted that there are wide ranges in the proportions of the major FA in all populations studied.ZusammenfassungIn der vorliegenden Studie wurde die Fettsäurenkomposition des subkutanen Fettgewebes (SCF) von 47 deutschen Erwachsenen analysiert. Es zeigte sich kein Zusammenhang zwischen dem Alter bzw. Geschlecht der Probanden und dem Fettsäurenstatus. Monoene bildeten den Hauptanteil der Fettsäuren (FA) im SCF. Linolsäure war die wichtigste mehrfach ungesättigte Fettsäure. Linolsäuremetaboliten wurden nur in geringen Mengen gefunden. Im Vergleich zu den Ergebnissen von Studien in den USA und den Niederlanden ist die FA-Zusammensetzung des SCF bei deutschen Probanden durch geringere Anteile von Linolsäure und höhere Anteile von Palmitinsäure gekennzeichnet. Der Gehalt an trans-FA entspricht dem, der bei Frauen in den Niederlanden gefunden wurde, er ist jedoch deutlich niedriger als bei amerikanischen Männern. In der Beurteilung der Unterschiede in der Fettsäurenkomposition des SCF in verschiedenen Ländern sollte jedoch berücksichtigt werden, daß die Anteile der wichtigsten FA in allen untersuchten Populationen eine große interindividuelle Schwankungsbreite zeigten.

Vitamin E status in Sudanese children with protein-energy malnutrition.

SummaryTotal tocopherols and alpha-tocopherols were estimated in the plasma of children with severe malnutrition (14 marasmus; 11 marasmic kwashiorkor; five kwashiorkor) and related to the total plasma lipids and different plasma lipid classes. If the mere plasma concentrations were taken as an index of the vitamin E status, five children with marasmus, five children with marasmic kwashiorkor, and two children with kwashiorkor would have been regarded as deficient (<500 μg/dl). However, if total tocopherols and alpha-tocopherols were related to the total plasma lipids, all malnourished children — except one — showed values within the limits found in healthy American children. The study shows that low tocopherol/lipid ratios are not a constant feature in severely malnourished children.ZusammenfassungDas Gesamttocopherol und alpha-Tocopherol wurden im Plasma von Kindern mit schwerer Mangelernährung (14 Maramus; 11 marantischer kwashiorkor; 5 kwashiorkor) bestimmt und auf die Gesamtlipide des Plasmas und auf die verschiedenen Plasmalipidklassen bezogen. Wenn die reinen Plasmakonzentrationen als ein Index des Vitamin-E-Status genommen würden, so wären 5 Kinder mit Marasmus, 5 Kinder mit marantischem kwashiorkor und 2 Kinder mit kwashiorkor als defizitär (<500 μg/dl) anzusehen. Werden jedoch Gesamttocopherol und alpha-Tocopherol auf die Gesamtlipide bezogen, so zeigten alle mangelernährten Kinder — bis auf eines — Werte, die innerhalb der Grenzen lagen, die für gesunde amerikanische Kinder gefunden wurden. Die Studie zeigt, daß niedrige Tocopherol-Lipid-Verhältnisse kein konstantes Merkmal bei schwer mangelernährten Kindern sind.

Composition of foods and dishes commonly consumed in villages of the Gezira area of Sudan. III. Fatty Acids, Retinol, α‐, β‐ Carotene and Tocopherols

It is known that the fat content of ready‐to‐eat dishes of the people in the Gezira area of Sudan is low. In order to judge the adequacy intake of the essential fatty acids (FA), the FA composition of foods and dishes commonly consumed was analysed. Percentages of fatty acids are given for several types of sorghum, millet, sesame, fenugreek, different sorts of peas, as well as for processed foods like gruels, sauces, local thin‐leaf bread and vegetables. Because there is also a lack of information on the vitamin A and E contents of these food items and ready‐to‐eat meals in this area, retinol, a‐, s‐carotene and tocopherols were chemically estimated and their contents are given for most of the important foodstuffs.