[Determination of sodium salt of benzoic acid, of paraaminobenzoic acid, of salicylic acid and of paraaminosalicylic acid].
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4-Aminobenzoic Acid↗
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Experimental and theoretical studies of the kinetics of the reactions of OH radicals with acetic acid, acetic acid-d3 and acetic acid-d4 at low pressure.
The kinetics of the reactions of OH with acetic acid, acetic acid-d3 and acetic acid-d4 were studied from 2 to 5 Torr and 263-373 K using a discharge flow system with resonance fluorescence detection of the OH radical. The measured rate constants at 300 K for the reaction of OH with acetic acid and acetic acid-d4 (CD3C(O)OD) were (7.42+/-0.12)x10(-13) and (1.09+/-0.18)x10(-13) cm3 molecule-1 s-1 respectively, and the rate constant for the reaction of OH with acetic acid-d3 (CD3C(O)OH) was (7.79+/-0.16)x10(-13) cm3 molecule-1 s-1. These results suggest that the primary mechanism for this reaction involves abstraction of the acidic hydrogen. Theoretical calculations of the kinetic isotope effect as a function of temperature are in good agreement with the experimental measurements using a mechanism involving the abstraction of the acidic hydrogen through a hydrogen-bonded complex. The rate constants for the OH+acetic acid and OH+acetic acid-d4 reactions display a negative temperature dependence described by the Arrhenius equations kH(T)=(2.52+/-1.22)x10(-14) exp((1010+/-150)/T) and kD(T)=(4.62+/-1.33)x10(-16) exp((1640+/-160)/T) cm3 molecule-1 s-1 for acetic acid and acetic acid-d4, respectively, consistent with recent measurements that suggest that the lifetime of acetic acid at the low temperatures of the upper troposphere is shorter than previously believed.
Journal Article↗
Stereospecific formation of (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-en-26-oic acid and (24R,25S)-3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid from either (25R)- or (25S)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid by rat liver homogenate.
Studies of the stereochemistry of the intermediates, 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-en-26-oic acid and 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid, in the biosynthetic sequence between 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid and cholic acid have been undertaken. (25R)- or (25S)-3 alpha,7 alpha, 12 alpha-Trihydroxy-5 beta-cholestan-26-oic acid was incubated with rat liver homogenates. The reaction products were converted to p-bromophenacyl ester derivatives and the esters were analyzed by high-performance liquid chromatography. By comparison with authentic samples of two (24E)- and (24Z)-isomers of the alpha, beta-unsaturated acid and of four isomers at C-24 and C-25 of the beta-hydroxy acid, (24E)-3 alpha,7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid and (24R,25S)-3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid were found to be formed from either (25R)- or (25S)-3 alpha,7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid. No formation of the (24Z)-isomer of the trihydroxycholestenoic acid or the other three isomers of the tetrahydroxycholestanoic acid was detected. The findings are discussed in relation to the assumed pathway for side chain cleavage in cholic acid biosynthesis.
Animals↗
Metabolism of sulfur-containing amino acids in the dermatophyte Microsporum gypseum. II. Acidic amino acid derivatives.
The dermatophyte Microsporum gypseum was cultivated on a glucose-arginine medium supplemented with five strongly acidic derivatives of cysteine (L-cysteine sulfinic acid, L-cysteic acid, L-serine-O-sulfate and taurine at a concentration of 5 mmol/l, and L-S-sulfocysteine at a concentration of 2.5 mmol/l). The addition of these substances did not stimulate the growth as compared with the control containing 0.5 mmol/l cystine. Cysteine sulfinic acid and cysteic acid showed rather inhibitory effects. A strong inhibition of the growth was caused by the presence of serine sulfate. During the growth, all substances investigated were gradually consumed and utilized not only as a source of sulfur but of nitrogen and carbon as well. Cysteine sulfinic acid and S-sulfocysteine were utilized most rapidly. Cysteic acid was also rapidly utilized but after a certain adaptation. Taurine was utilized slowly and serine sulfate very slowly. Excess sulfur contained in the substances used was excreted into the medium in the form of sulfate. Sulfate excretion was most rapid with cysteine sulfinic acid and slowest with taurine. With cysteine sulfinic acid, S-sulfocysteine and cysteic acid, small amounts of sulfite were found in the medium. The results obtained are in accordance with the presumption that cysteine sulfinic acid (but not cysteic acid and taurine) is an intermediate of cysteine catabolism in dermatophytes.
Amino Acids, Sulfur↗
Analysis of the toxic effects of linoleic acid, 12,13-cis-epoxyoctadecenoic acid, and 12,13-dihydroxyoctadecenoic acid in rabbit renal cortical mitochondria.
P450 epoxidation of linoleic acid has been associated with many pathological conditions that often lead to acute renal failure. However, there is only suggestive evidence that linoleic acid monoepoxides and/or linoleic diols directly induce mitochondrial dysfunction. Using isolated rabbit renal cortical mitochondria (RCM), we found that linoleic acid (50 microM) and the linoleic acid monoepoxide, cis-12,13-epoxy-9-octadecenoic acid (12,13-EOA, 50 microM) increased state 4 and oligomycin-insensitive respiration and reduced state 3 and oligomycin-sensitive respiration. Concomitant with these effects, linoleic acid and 12,13-EOA decreased mitochondrial membrane potential (DeltaPsi). In contrast, the hydrolyzed product of 12,13-EOA, 12,13-dihydroxyoctadecenoic acid (12,13-DHOA, 50 microM), had no effect on state 3, state 4, oligomycin-sensitive, and oligomycin-insensitive respiration, and DeltaPsi. Neither linoleic acid or its metabolites altered uncoupled respiration, which suggests that these compounds have no affect on electron transport chain in RCM. Nucleotides such as ATP (0.5 mM) and GDP (0.5 mM) partially prevented the decrease in DeltaPsi but did not attenuate the increase in oligomycin-insensitive respiration after exposure to linoleic acid (50 microM) and 12,13-EOA (50 microM). These results demonstrate that linoleic acid metabolism to the 12,13-DHOA is a detoxification pathway that prevents mitochondrial dysfunction in RCM. The increase in state 4 respiration concomitant with decreases in state 3 respiration and DeltaPsi suggest that, in addition to uncoupling effects, linoleic acid and 12,13-EOA may have other effects, such as alterations of mitochondrial membranes. The inability of ATP and GDP to fully attenuate the uncoupling effects of linoleic acid and 12,13-EOA suggests that these effects are mediated through a nucleotide-independent mechanism.
Adenosine Triphosphate↗
Effects of acromelic acid A on the binding of [3H]glutamic acid and [3H]kainic acid to synaptic membranes and on the depolarization at the frog spinal cord.
Triton treatment of synaptic membranes from the frog spinal cord enhanced the specific binding of [3H]glutamic acid compared with non-treated fresh and frozen ones, but not that of [3H]kainic acid. Acromelic acid A specifically inhibited the binding of [3H]kainic acid, and was approximately 100 times more potent than kainic acid. Acromelic acid A and excitatory amino acids caused a depolarization in the ventral root of the frog spinal cord in a dose-dependent manner, and the effect of acromelic acid A was much superior to that of kainic acid or domoic acid. Acromelic acid A is one of the most potent kainic acid agonist at the frog spinal cord.
Animals↗
Inhibition of high affinity L-glutamic acid uptake into rat cortical synaptosomes by the conformationally restricted analogue of glutamic acid, cis-1-aminocyclobutane-1,3-dicarboxylic acid.
The action of two cyclobutane derivatives of L-glutamic acid on the high affinity uptake of L-glutamic acid was investigated using a preparation of synaptosomes from rat cerebral cortex. cis-1-Aminocyclobutane-1,3-dicarboxylic acid (also known as trans-2,4-methanoglutamic acid) potently inhibited L-glutamic acid uptake (IC50 30 microM), whereas trans-1-aminocyclobutane-1,3-dicarboxylic acid (also known as cis-2,4-methanoglutamic acid), a potent N-methyl-D-aspartate (NMDA) agonist, was inactive. Analysis of the kinetics of L-glutamic acid uptake in the presence and absence of cis-1-aminocyclobutane-1,3-dicarboxylic acid (CACB) suggests that it may act as a competitive inhibitor (Ki 8 microM). CACB may be substrate for the L-glutamic acid high-affinity uptake carrier since preincubation of CACB with the synaptosomal preparation increased its potency in inhibiting L-glutamic acid uptake. The conformationally restricted structure of CACB may be indicative of the conformations of L-glutamic acid that interact with the high affinity uptake carrier.
Amino Acids, Dicarboxylic↗
The effect of feeding with a tryptophan-free amino acid mixture on rat liver magnesium ion-activated deoxyribonucleic acid-dependent ribonucleic acid polymerase.
1. The Widnell & Tata (1966) assay method for Mg(2+)-activated DNA-dependent RNA polymerase was used for initial-velocity determinations of rat liver nuclear RNA polymerase. One unit (U) of RNA polymerase was defined as that amount of enzyme required for 1 mmol of [(3)H]GMP incorporation/min at 37 degrees C. 2. Colony fed rats were found to have a mean RNA polymerase activity of 65.9muU/mg of DNA and 18h-starved rats had a mean activity of 53.2muU/mg of DNA. Longer periods of starvation did not significantly decrease RNA polymerase activity further. 3. Rats that had been starved for 18h were used for all feeding experiments. Complete and tryptophan-deficient amino acid mixtures were given by stomach tube and the animals were killed 15-120min later. The response of RNA polymerase to the feeding with the complete amino acid mixture was rapid and almost linear over the first hour of feeding, resulting in a doubling of activity. The activity was still elevated above the starvation value at 120min after feeding. The tryptophan-deficient amino acid mixture produced a much less vigorous response about 45min after the feeding, and the activity had returned to the starvation value by 120min after the feeding. 4. The response of RNA polymerase to the feeding with the complete amino acid mixture was shown to occur within a period of less than 5min to about 10min after the feeding. 5. Pretreatment of the animals with puromycin or cycloheximide was found to abolish the 15min RNA polymerase response to the feeding with the complete amino acid mixture, but the activity of the controls was unaffected. 6. The characteristics of the RNA polymerase from 18h-starved animals and animals fed with the complete or incomplete amino acid mixtures for 1h were examined. The effects of Mg(2+) ions, pH, actinomycin D and nucleoside triphosphate omissions were determined. The [Mg(2+)]- and pH-activity profiles of the RNA polymerase from the animal fed with the complete mixture appeared to differ from those of the enzyme from the other groups, but this difference is probably not significant. 7. [5-(3)H]Orotic acid incorporation by rat liver nuclei in vivo was shown to be affected by the amino acid mixtures in a similar manner to the RNA polymerase. 8. The tryptophan concentrations of plasma and liver were determined up to 120 min after feeding with the amino acid mixtures. Feeding with the complete mixture produced a rapid increase in free tryptophan concentrations in both plasma and liver, but feeding with the incomplete mixture did not alter the plasma concentration. The liver tryptophan concentration increased at about 45min after feeding with the tryptophan-deficient diet. 9. There was a good correlation between the liver tryptophan concentration and RNA polymerase activity in all groups of animals. 10. It was concluded that the rat liver nucleus responded to an increase in amino acid supply by increased synthesis of RNA as a result of synthesis of RNA polymerase de novo. The correlation of tryptophan concentration and RNA polymerase activity appears to reflect the general amino acid concentration required to support hepatic protein synthesis and to produce new RNA polymerase. This new polymerase appears to differ from the basal RNA polymerase by its rapid synthesis and destruction, which may be a means of regulating RNA synthesis by the amino acid concentration in the liver.
Amino Acids↗
Maleic acid and succinic acid in fermented alcoholic beverages are the stimulants of gastric acid secretion.
Alcoholic beverages produced by fermentation (e.g., beer and wine) are powerful stimulants of gastric acid output and gastrin release in humans. The aim of this study was to separate and specify the gastric acid stimulatory ingredients in alcoholic beverages produced by fermentation. Yeast-fermented glucose was used as a simple model of fermented alcoholic beverages; it was stepwise separated by different methods of liquid chromatography, and each separated solution was tested in human volunteers for its stimulatory action on gastric acid output and gastrin release. Five substances were detected by high-performance liquid chromatography and were analyzed by mass spectrometry and 1H-13C nuclear magnetic resonance spectroscopy. At the end of the separation process of the five identified substances, only the two dicarboxylic acids, maleic acid and succinic acid, had a significant (P < 0.05) stimulatory action on gastric acid output (76% and 70% of fermented glucose, respectively), but not on gastrin release. When given together, they increased gastric acid output by 100% of fermented glucose and by 95% of maximal acid output. We therefore conclude that maleic acid and succinic acid are the powerful stimulants of gastric acid output in fermented glucose and alcoholic beverages produced by fermentation, and that gastrin is not their mediator of action.
Adult↗
Bile acid sulfotransferase I from rat liver sulfates bile acids and 3-hydroxy steroids: purification, N-terminal amino acid sequence, and kinetic properties.
A bile acid:3'phosphoadenosine-5'phosphosulfate:sulfotransferase (BAST I) from adult female rat liver cytosol has been purified 157-fold by a two-step isolation procedure. The N-terminal amino acid sequence of the 30,000 subunit has been determined for the first 35 residues. The Vmax of purified BAST I is 18.7 nmol/min per mg protein with N-(3-hydroxy-5 beta-cholanoyl)glycine (glycolithocholic acid) as substrate, comparable to that of the corresponding purified human BAST (Chen, L-J., and I. H. Segel, 1985. Arch. Biochem. Biophys. 241: 371-379). BAST I activity has a broad pH optimum from 5.5-7.5. Although maximum activity occurs with 5 mM MgCl2, Mg2+ is not essential for BAST I activity. The greatest sulfotransferase activity and the highest substrate affinity is observed with bile acids or steroids that have a steroid nucleus containing a 3 beta-hydroxy group and a 5-6 double bond or a trans A-B ring junction. These substrates have normal hyperbolic initial velocity curves with substrate inhibition occurring above 5 microM. Of the saturated 5 beta-bile acids, those with a single 3-hydroxy group are the most active. The addition of a second hydroxy group at the 6- or 7-position eliminates more than 99% of the activity. In contrast, 3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oic acid (deoxycholic acid) is an excellent substrate. The initial velocity curves for glycolithocholic and deoxycholic acid conjugates are sigmoidal rather than hyperbolic, suggestive of an allosteric effect. Maximum activity is observed at 80 microM for glycolithocholic acid. All substrates, bile acids and steroids, are inhibited by the 5 beta-bile acid, 3-keto-5 beta-cholanoic acid. The data suggest that BAST I is the same protein as hydrosteroid sulfotransferase 2 (Marcus, C. J., et al. 1980. Anal. Biochem. 107: 296-304).
Amino Acid Sequence↗
Fish oil reduces cholesterol and arachidonic acid content more efficiently in rats fed diets containing low linoleic acid to saturated fatty acid ratios.
Rats were fed diets containing a high level of saturated fatty acids (hydrogenated beef tallow) versus a high level of linoleic acid (safflower oil) at both low and high levels of fish oil containing 7.5% (w/w) eicosapentaenoic and 2.5% (w/w) docosahexaenoic acids for a period of 28 days. The effect of feeding these diets on the cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding diets high in fish oil with safflower oil decreased the cholesterol content of rat serum, whereas feeding fish oil had no significant effect on the cholesterol content of serum when fed in combination with saturated fatty acids. The serum cholesterol level was higher in animals fed safflower oil compared to animals fed saturated fat without fish oil. Consumption of fish oil lowered the cholesterol content of liver tissue regardless of the dietary fat fed. Feeding diets containing fish oil reduced the arachidonic acid content of rat serum and liver lipid fractions, the decrease being more pronounced when fish oil was fed in combination with hydrogenated beef tallow than with safflower oil. These results suggest that dietary n-3 fatty acids of fish oil interact with dietary linoleic acid and saturated fatty acids differently to modulate enzymes of cholesterol and fatty acid metabolism.
Animals↗
Isolation and identification of alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone radical adducts formed by the decomposition of the hydroperoxides of linoleic acid, linolenic acid, and arachidonic acid by soybean lipoxygenase.
alpha-(4-Pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) radical adducts, which are formed in the reactions of soybean lipoxygenase with linoleic acid, arachidonic acid, and linolenic acid, were isolated using HPLC-ESR spectroscopy. Both linoleic acid and arachidonic acid gave one radical adduct, whereas in the case of linolenic acid, two radical adducts were isolated. These radical adducts all showed virtually identical uv spectra with lambda max at 292 and 220 nm in hexane. The absence of absorbance with lambda max at 234 nm indicates that a conjugated diene structure is not contained in these radical adducts. The mass spectra of the radical adducts formed from linoleic and arachidonic acids were identical and contained a molecular ion of m/z 264, consistent with the trapping of the pentyl radical by 4-POBN. Indeed, authentic 4-POBN pentyl radical adduct obtained from the reaction between pentylhydrazine and 4-POBN gave the same mass spectrum as the product obtained from the reaction of linoleic acid and arachidonic acid with 4-POBN. The two 4-POBN radical adducts formed in the linolenic acid reaction were shown by mass spectrometry to be isomers of pentenyl radicals. The 4-POBN-pentyl radical adduct was also detected in the reaction mixture of 13-hydroperoxy-linoleic acid, soybean lipoxygenase, and 4-POBN, indicating that the pentyl radical and pentenyl radical are formed by the decomposition of the hydroperoxides.
Arachidonic Acids↗
Pb(II)-binding capability of aminohydroxamic acids: primary hydroxamic acid derivatives of alpha-amino acids as possible sequestering agents for Pb(II).
Complexes of aminohydroxamic acids, D,L-alpha-alaninehydroxamic acid (alpha-Alaha), sarcosinehydroxamic acid (Sarha), D,L-N-methyl-alpha-alaninehydroxamic acid (N-Me-alpha-Alaha), beta-alaninehydroxamic (beta-Alaha), L-aspartic acid-beta-hydroxamic acid (Asp-beta-ha), L-glutamic acid-gamma-hydroxamic acid (Glu-gamma-ha) and L-histidinehydroxamic acid (Hisha) with lead(II) in aqueous solution were studied by pH-potentiometric, 1H NMR and electrospray ionization mass spectrometric (ESI MS) methods. The results were compared to those of a simple monohydroxamic acid, acetohydroxamic acid and the effects of the amino group, hydroxamate-N, as well as, additional side chain donors on the co-ordination mode and on the stability of the complexes formed were evaluated. It was found that the amino nitrogen atom situating in beta- or in gamma-position (beta-Alaha, Asp-beta-ha, Glu-gamma-ha) does not co-ordinate to Pb(II), only hydroxamate type chelates are formed before the hydrolytic processes. However, the amino-N in alpha-position (alpha-Alaha, Sarha, Hisha) seems to form a stable 5-membered (N,N)-type chelate together with the deprotonated hydroxamate-N above pH 6. On the other hand, the hydroxamate (O,O)-type chelate also exists. Since steric reasons do not allow the coordination of these two chelates of a molecule to the same Pb(II) ion, polynuclear complexes with mixed co-ordination modes are formed with the alpha-derivatives above pH 6. Simple hydroxamate type complexes are formed with N-Me-alpha-Alaha, where the hydroxamate-N is not able to co-ordinate. The co-ordination of the side chain imidazole of Hisha is not measurable, while a weak interaction of the side chain carboxylates of Asp-beta-ha and especially of Glu-gamma-ha can be suggested.
Amino Acids↗
Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.
The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.
Benzene Derivatives↗
Effects of dihydroxy bile acids and hydroxy fatty acids on the absorption of oleic acid in the human jejunum.
Perfusion studies of the normal human jejunum were performed to test whether dihydroxy bile acids and hydroxy fatty acids inhibit the absorption of oleic acid, since previous reports documented their inhibitory effects on the absorption of several other organic solutes. 3 mM deoxycholate and 7 mM glycodeoxycholate inhibited the absorption of 3 mM oleic acid in isotonic micellar solutions while inducing net fluid secretion. Similarly, fractional absorption of oleic acid decreased in the presence of hydroxy fatty acids. However, only the changes induced by 2 mM ricinoleic acid could be distinguished from changes induced by an increase in total fatty acid concentration. Under all experimental conditions, close linear relationships existed between net water movement and fractional absorption of glucose, xylose, and fatty acids, as well as between the absorption rates of these solutes. In contrast, net fluid secretion induced by hypertonic D-mannitol (450 mosmol/liter) had no effect on solute absorption. Our data and observations in the literature do not allow formulation of a hypothesis which would adequately define all effects of dihydroxy bile acids and fatty acids on intestinal transport processes. The observations help explain the malabsorption of fat and other nutrients in patients with the blind loop syndrome.
Adult↗
Effect of diets rich in oleic acid, stearic acid and linoleic acid on postprandial haemostatic factors in young healthy men.
The aim of the present study was to investigate the effects of stearic acid-, oleic acid- and linoleic acid-rich meals on postprandial haemostasis in young healthy volunteers whose background diets had been controlled for 14 d in a residential study. Six healthy male volunteers were assigned randomly to consume diets rich in stearic acid, oleic acid or linoleic acid for 14 d. On day 15, plasma lipids and haematological variables were measured in the fasted state, and 3 and 7 h (factor VII and prothrombin activation peptide fragments, 1 and 2 only) after consumption of a test meal. Test meals provided 40 % of the subjects' daily energy requirement, with 41 % of the energy provided as fat, 17 % energy as protein and 42 % energy as carbohydrate. The mean fat content of the meal was 45 (sd 5) g. Significant alterations from fasted values were observed for activated factor VII after 7 h), factor VII antigen after 7 h), prothrombin activation peptide fragments 1 and 2 after 7 h) and plasminogen activator inhibitor type 1 activity after 3 h) after consumption of each of the three meals. No significant differences were observed in haemostatic values (factor VII coagulant activity, factor VII antigen, tissue plasminogen activator activity prothrombin activation peptide fragment and plasminogen activator inhibitor type-1) with regard to diet except for activated factor VII at 3 h; values were higher after the oleic acid- and linoleic acid-rich meals than after the stearic acid-rich meal After consumption of each of the three meals, chylomicrons contained proportionately more palmitic acid than the lipids ingested. The present study shows that there are demonstrable changes in postprandial haemostasis when young healthy volunteers with controlled dietary backgrounds are challenged with a physiological fat load. These changes are independent of the fatty acid composition of the test meals.
Adult↗
The endogenous cofactors, thioctic acid and dihydrolipoic acid, are neuroprotective against NMDA and malonic acid lesions of striatum.
Thioctic acid (alpha-lipoic acid) and dihydrolipoic acid are endogenous, interconvertible cofactors of the mitochondrial pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes. These compounds help to maintain glutathione and alpha-tocopherol in their reduced states, and they possess intrinsic free radical scavenging properties. We examined whether systemic treatment with thioctic acid or dihydrolipoic acid is protective against direct- and indirect-acting excitotoxins. Adult rats were treated for 10 days with intraperitoneal injections of vehicle, thioctic acid or dihydrolipoic acid, and on day 7 of treatment animals received unilateral stereotaxic injections of NMDA or malonic acid into the striatum. Histological assessment 3 days after the stereotaxic injections revealed a marked reduction in lesion volume in animals treated with thioctic acid or dihydrolipoic acid. We conclude that thioctic acid and dihydrolipoic acid are neuroprotective against direct and indirect excitotoxic insults.
Animals↗
Control of fatty acid composition in phospholipids of Escherichia coli: response to fatty acid supplements in a fatty acid auxotroph.
The effect of exogenous unsaturated fatty acids on the fatty acid composition of phospholipids of a mutant of E. coli has been examined. These exogenous acids serve as growth factors for an auxotroph requiring unsaturated fatty acids. When each member of a structurally homologous series of cis-unsaturated fatty acids serves as a growth factor, the percentage of unsaturated fatty acid present in phospholipids increases with increasing chain length or decreasing number of double bonds in the apolar chain of the supplement. At 37 degrees , trans-octadecenoic acids support growth and are incorporated into phospholipids at levels higher than the corresponding cis-acids. However, a temperature shift to 27 degrees with trans-acids results in loss of viability and lysis. Utilization of cis-acids as supplements at decreasing temperatures between 42 degrees and 27 degrees results in increasing amounts of unsaturated fatty acids in phospholipids with decreasing temperature. These observations suggest the operation of a regulatory mechanism which controls the composition of saturated versus unsaturated acids in order to maintain the physical properties of phospholipids within narrow limits.
Alkenes↗