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PubMed1978

Micelle and acid-soap formation of linoleic acid and 13-L-hydroperoxylinoleic acid being substrates of lipoxygenase-1.

Surface tension measurements of linoleic acid solutions in 0.1 M sodiumborate buffer pH 10 at 23 degrees C showed that at increasing the linoleic acid concentration a sharp transition from monomers to micelles occurs at 167 micrometer. At pH 9 and 8 formation of acid-soap dimers from monomers starts at 60 micrometer and 21 micrometer respectively. The concentration range at which only monomers exist is therefore markedly reduced. For 13-L-hydroperoxylinoleic acid at pH 10 acid-soap formation still takes place, starting at approx. 220 micrometer. The total lipid concentration at which acid-soap or micelle formation starts in mixtures of linoleic acid and 13-L-hydroperoxylinoleic acid has been determined in relation to the molar ratio of both acids.

Kinetics↗
PubMed1975

Accumulation of 3-hydroxyisobutyric acid, 2-methyl-3-hydroxybutyric acid and 3-hydroxyisovaleric acid in ketoacidosis.

1. Urine and serum samples from patients with ketoacidosis of varying degree and etiology have been examined by gas chromatography and mass spectrometry. 2. In addition to 3-hydroxyisovaleric acid, relatively high concentrations of two analogous hydroxy acids, 3-hydroxyisobutyric acid and 2-methyl-3-hydroxybutyric acid, were found in the urine. 3. There were highly significant positive correlations between the excreted amounts of the three acids. 4. Experiments on rats with isotope-labelled compounds revealed that the acids were formed by the degradation of leucine, isoleucine and valine. 5. The accumulation of the hydroxy acids during ketoacidosis is probably caused by a similar derangement of the metabolism of all three branched-chain amino acids.

Acetates↗
PubMed1978

Lipid compositional manipulation in Acholeplasma laidlawii B. Effect of exogenous fatty acids on fatty acid composition and cell growth when endogenous fatty acid production is inhibited.

A variety of potential inhibitors of de novo fatty acid biosynthesis have been tested for activity in Acholeplasma laidlawii B. Two compounds, avidin and N,N-dimethyl-4-oxo-2trans-dodecenamide (CM-55), an antimicrobial fatty amide, strongly inhibit de novo biosynthesis without nonspecific toxic effects at moderate dosages. Avidin is the more potent inhibitor, abolishing de novo fatty acid synthesis and greatly reducing the chain elongation of exogenous fatty acids at level of 25 U/l. CM-55 gives complete inhibition of de novo biosynthesis only at low temperatures and inhibits exogenous fatty acid elongation to a variable extent. However, CM-55 is still a more potent antilipogenic agent in this organism than is the fungal antibiotic cerulenin. Cells cultured with avidin grow only when one or more exogenous medium- or long-chain fatty acids are added to the growth medium. The extent of cell growth under these conditions depends primarily on the physical properties of the exogenous fatty acid(s). In general, fatty acids giving diacylglycerolipids of very high or very low fluidity are unsuitable growth substrates, while those whose diacylglycerol derivatives are of intermediate fluidity support fair to good cell growth.

Acholeplasma laidlawii↗
PubMed1979

Faecal bile acid loss and bile acid pool size during short-term treatment with ursodeoxycholic and chenodeoxycholic acid in patients with radiolucent gallstones.

Twelve non-obese patients with radiolucent gallstones were fed on a standard diet. After 10 days (period A), six patients received 15 mg/kg/day of ursodeoxycholic acid (UDCA) (group I) and the other six (group II) the same dose of chenodeoxycholic acid (CDCA) for 15 days (period B). An intravenous injection of 20 micro Ci of 14C-UDCA and of 14C-CDCA was given on the 11th day of period B to the patients of group I and II respectively. Stools were collected at the end of period A and B and one bile sample was collected on the 12th day of period B. The faecal bile acid loss was higher during chenotherapy (36.12 mumol/kg/day) than during ursotherapy (23.94 mumol/kg/day), as was the proportion of lithocholic acid (73% vs 43%) in the faeces. Decay constant rate of faecal radioactivity was 0.365 day-1 in group I and 0.642 in group II. The results indicate that faecal bile acid excretion and turnover rate are greater during CDCA than UDCA, while UDCA increases the bile acid pool size to an even greater extent than does CDCA (150.2 vs 94.9 mumol/kg). This is probably because the former is more slowly degraded to poorly reabsorbable compounds. In fact, the bile saturation index was 0.66 in group I and 1.05 in group II, even though biliary CDCA in the latter had risen to 69.6%.

Bile Acids and Salts↗
PubMed1978

Simultaneous determination by GC-MS-SIM of o-, m-, p-hydroxyphenylacetic acid, 3:4-dihydroxyphenylacetic acid and homovanillic acid in biological samples using a common selected ion.

A GC-MS-SIM method is described for the simultaneous determination of five acid metabolites, o-, m-, and p-hydroxyphenylacetic acid, 3:4-dihydroxyphenylacetic acid and homovanillic acid in biological samples using a common selected ion for all the acids. The TMS ethers of methyl or ethyl esters of these compounds have a common ion at m/e 179 which is used for their quantitation by selected ion monitoring. The molecular ion at m/e 238 of the three monohydroxy phenylacetic acids, which is also the M-30 ion for homovanillic acid, is also used for their quantitation. The GC conditions for their separation, the relative sensitivities and some advantages of TMS ethers over other derivatives are described. The application of this method to biological samples is illustrated by data on human urine and plasma.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1975

The estimation of 3,4-dihydroxyphenylacetic acid, homovanillic acid and homo-isovanillic acid in nervous tissue by gas-liquid chromatography and electron capture detection.

1 A gas chromatographic method using electron capture detection is described for the estimation of three acidic metabolites of dopamine, 4-hydroxy-3-methoxyphenylacetic acid (homovanillic acid, HVA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-hydroxy-4-methoxyphenylacetic acid (homo-isovanillic acid, iso-HVA). The method is based on the formation of the trifluoroacetyl-hexafluoroisopropyl derivatives of the three acids. 2 The method has been applied to the estimation of DOPAC, HVA and iso-HVA in tissues from the central and peripheral nervous systems.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1975

[A possible essential metabolite of linoleic acid: lipoic acid, the universal coenzyme of alpha-keto acid oxidation].

The metabolism of [14C-U] linoleci acid (LI) and [14C-U] oleic acid were compared by injecting these fatty acids into growing rats and then homogenizing livers into a three phase system (chloroform/methanol/water). The radioactivities of these phases were equilibrated by extracting them X times with the same solvents. The lipid lower phase was discarded and the analysis was carried out on the evaporated hydroalcoholic upper phase. The residue was extracted again with methanol and hydrolyzed (HCl 6N). The acidic solution was evaporated, treated with HCl/methanol, extracted with chloroform and analysed by thin layer chromatography. One of the most radioactive intermediates detected after injecting LI was purified again and identified as lipoic acid, on the basis of: a. retention time in gas-liquid chromatography; b. Rf in thin layer chromatography; c. molecular weight as determined by mass spectrometry. Thus, the most important fate of essential fatty acids (except for their part in the prostaglandin synthesis and membrane formation) seems to be that of a precursor for this covalently bound alpha keto-acid dehydrogenation coenzyme--the link between lipid and carbohydrate metabolisms.

Animals↗
PubMed1979

Regulation of the biosynthesis of aminoacyl-transfer ribonucleic acid synthetases and of transfer ribonucleic acid in Escherichia coli. VI. Mutants with increased levels of glutaminyl-transfer ribonucleic acid synthetase and of glutamine transfer ribonucleic acid.

Spontaneous revertants of a temperature-sensitive Escherichia coli strain bearing a thermolabile glutaminyl-transfer ribonucleic acid (tRNA) synthetase have been selected for growth at 45 degrees C. Among 10 revertants still containing the thermolabile enzyme, 2 interesting strains were found. One strain has a fivefold elevated level of the thermolabile glutaminyl-tRNA synthetase; the genetic locus, glnR, responsible for this effect maps at min 24, far from glnS, the structural gene of the enzyme. In the other strain the levels of tRNA Gln and several other tRNAs are twice as high as in the parental strain; the locus responsible, glnU, maps at min 59.5 on the E. coli map.

Amino Acyl-tRNA Synthetases↗
PubMed1979

Relationship between essential fatty acid requirements of aquatic animals and the capacity for bioconversion of linolenic acid to highly unsaturated fatty acids.

1. [1-14C]linolenic acid was injected into the rainbow trout, Salmo gairdnerii, ayu, Plecoglossus altivelis, eel, Anguilla japonica, red sea bream, Chrysophrys major, rockfish, Sebastiscus marmoratus, globefish, Fugu rubripes rubripes and prawn, Penaeus japonicus (molting stage D"1-D2), and the bioconversion of linolenic acid (18:3 omega 3) to highly unsaturated fatty acids such as eicosapentaenoic (20:5 omega 3) and docosahexaenoic (22:6 omega 3) acids was investigated. 2. Linolenic acid was converted to 20:5 omega 3 and 22:6 omega 3 intensively in the rainbow trout, moderately in the ayu, eel and prawn, but slightly in the red sea bream, rockfish and globefish. 3. These results were discussed in relation to the essential fatty acid requirements of the aquatic animals.

Animals↗
PubMed1976

Transformation of arachidonic acid and homo-gamma-linolenic acid by rabbit polymorphonuclear leukocytes. Monohydroxy acids from novel lipoxygenases.

Addition of arachidonic acid and homo-gamma-linolenic acid to a suspension of rabbit peritoneal neutrophils led to the synthesis of 5-L-hydroxy-6,8,11,14-eicosatetraenoic acid and 8-L-hydroxy-9,11,14-eicosatrienoic acid, respectively. Both hydroxy acids were found to be the main metabolites of their respective unsaturated C-20 fatty acid precursor, constituting more than 50% of the total substrate conversion. The formation of the two metabolites was not inhibted bb indomethacin, indicating that the enzymes involved were unrelated to the prostaglandin synthetase system. The presence in the two compounds of a hydroxyl group alpha to a pair of conjugated cis/trans double bonds suggested that they were formed by action of lipoxygenease(s).

8,11,14-Eicosatrienoic Acid↗
PubMed1977

Acidic dissociation constants of folic acid, dihydrofolic acid, and methotrexate.

The acidic dissociation constants in the range HO--1.5 to pH 7 of folic acid, dihydrofolic acid, methopterin (N(10)methylfolic acid), and methotrexate have been measured by potentiometric and spectrophotometric titrations. Assignment of these dissociations was made by comparison to model compounds, by proton magnetic resonance measurements, and by examination of associated ultraviolet absorbance changes. For folic acid, the dissociation constants are as follows: N(1), pK' 2.35; N(10), pK' 0.20; N(5), pK' greater than -1.5. For dihydrofolic acid: N(5), pK' 3.84; N(1), pK' 1.38; N(10), pK' 0.28. For methotrexate: N(1), pK' 5.71; gamma-carboxyl, pK' 4.70; alpha-carboxyl, pK' 3.36; N(10), pK' 0.50; N(5), boxyl, pK' 4.70; alpha-carboxyl, pK' 3.36; N(10), pK' 0.50; N(5) pK' greater than -1.5. For methopterin: acidic ionization of amide, pK' 7.68; gamma-carboxyl, pK' 4.62; N(1), pK' 2.40; N(10), pK; 0.36; N(5), pK' greater than -1.5. The pK' values were determined directly for the four compounds at 25 degrees near 0.1 ionic strength, or in 0.1 to 4 M HCl for pK ln 0.1 M NaCl.

Chemical Phenomena↗
PubMed1977

Depletion of docosahexaenoic acid in retinal lipids of rats fed a linolenic acid-deficient, linoleic acid-containing diet.

Rats were raised for 2 generations on a diet in which 1.25% methyl linoleate was the only source of fat. Control rats were given 1.0% methyl linoleate plus 0.25% methyl linolenate. Lipids were extracted from retinas and their fatty acids were analyzed by gas-liquid chromatography. Docosahexaenoic acid accounted for 33.8% of total fatty acids in control retinas, for 13% of fatty acids in first-generation deficient retinas, and for 2.7% of fatty acids in second-generation deficient retinas.

Animals↗
PubMed1976

[Investigations on the utilization of parenterally administered amino acids in premature and small-for-dates neonates. IV. Control of the amino acid blood level during infusion of a pharmacokinetically balanced amino acid solution (author's transl)].

An amino acid solution composed according to pharmacokinetic criteria was infused in 12 premature and 4 full-term infants. Imbalances of amino acids were not observed when the upper limit of the fasting level was accepted as a measure for balance or imbalance. The net transfer of total amino acids increased by about 40% over that in former experiments (second communication (4)). A decrease of cystine, a semiessential amino acid, could be avoided. The results were compared with the literature. During infusion, the urinary excretion of amino acids was not increased showing nearly complete utilization of the infused amin acids.

Amino Acids↗
PubMed1978

Reduction in medium chain acids and monoenoic acids in livers and plasma of rats fed eicosa-5,8,11, 14-tetraynoic acid.

Male Sprague-Dawley rats were fed for 8 weeks a corn oil (CO) diet or a hydrogenated coconut oil (HCNO) diet. These diets were fed in the absence or presence of eicosa-5,8,11,14-tetraynoic acid (TYA). The inclusion of TYA in the HCNO diet reduced the levels of 12:0 and 14:0 in the total fatty acids of livers and plasma. With either diet, the presence of TYA caused an alteration in the fatty acid composition of these tissues so as to reduce the values of the ratios: 16:1/16:0, 18:1/18:0. and 20:4/18:2. These results suggest that dietary TYA can influence the hepatic metabolism of medium chain fatty acids and that it may inhibit the desaturase enzyme involved in the synthesis of not only 20:4 but also of monoenoic fatty acids.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1978

The effect of dihomo-gamma-linolenic acid (20: 3,n-6) on the composition of phospholipid fatty acids in the liver of rats deficient in essential fatty acids.

1. Rats were fed on either a diet deficient in essential fatty acid (EFA) or one supplemented with dihomo-gamma-linolenic acid (20:3,n-6) at levels that represented 0.25, 0.5, 1.0 and 2.0% of the dietary energy. 2. Supplementation of the diet of EFA-deficient animals with 20:3,n-6 reversed most of the fatty acid changes induced in the liver phospholipid fraction. 3 The EFA potency of 20:3,n-6 was found to be similar to that of gamma-linolenic acid (18:3,n-6) which has been shown to be higher than that of linoleic acid (18:2,n-6).

8,11,14-Eicosatrienoic Acid↗
PubMed1978

Ranking of excitatory amino acids by the antagonists glutamic acid diethylester and D-alpha-aminoadipic acid.

A separation of the excitatory actions of the amino acids upon thalamic neurones of rats anaesthetized with urethane has been accomplished through the use of two antagonists. It has been possible to rank the excitatory compounds in their order of susceptibility to D-alpha-aminoadipic acid (DalphaAA) and L-glutamic acid diethylester (GDEE). The observation that the ranking orders of the excitants differ for these two antagonists permits an analysis of the types of receptors with which the amino acid excitants react. The results support the proposition that more than one neuronal receptor sensitive to the amino acids exists.

2-Aminoadipic Acid↗
PubMed1977

[Determination of the urinary metabolites hydroxyindole-acetic acid, vanillyl mandelic acid and homovanillic acid by means of lipophilic gel chromatography and gas chromatography (author's transl)].

A specific and practicable method is described for the quantitative determination of urinary phenol- and indole-carboxylic acids. High specificity is achieved by a preliminary separation of the free acids (extracted from the urine sample) with the aid of organophilic gel chromatography on Sephadex LH 20, followed by gas chromatographic analysis of the silyl derivatives of the acids. The organophilic gel chromatography of the free acids shows a high recovery rate in the micro- and submicrogram range. The difficulties encountered in other techniques in the derivatisation and gas chromatographic separation of the individual components are avoided by using the preliminary separation, and by using N-methyl-N-trimethylsilyl-trifluoroacetamide for the derivatisation. Use of this preparation technique with a direct read-out gas chromatograph with automatic sample introduction, gives high accuracy and precision, and a facility for the determination of a wide range of aromatic acids in urine.

Chromatography, Gas↗