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At least 865 records · Page 48Linked to original sources
PubMed1972

Cellular fatty acid composition of selected Pseudomonas species.

The cellular fatty acid composition of 10 reference strains representing eight species of Pseudomonas was determined by gas-liquid chromatography. A variety of acids were detected in these organisms, including branched and straight-chained acids, cyclopropane, and hydroxy acids. Comparison of the presence and relative amounts of these acids among strains was useful for distinguishing various Pseudomonas species.

Chromatography, Gas↗
PubMed1979

Existence of carotenoids in Acholeplasma axanthum.

The neutral lipids of Acholeplasma axanthum contain carotenoid pigments, as evidenced by spectral characteristics, visual color, color reactions, and labeling with [2-14C-A1mevalonic acid. Approximately 80% of the label from [2-14C]mevalonic acid appeared in esterified fatty acids of the glycolipids and polar lipids. These carboxylic acids behaved as hydroxy acids of varying chain length.

Acholeplasma↗
PubMed1991

Structures of aureobasidins B to R.

Structures of 17 minor forms of aureobasidins (Abs), Abs B-R, were elucidated by mass fragmentation and amino acid analysis. The fragmentation patterns by FAB-MS spectroscopy of Abs A-E seemed to follow predictable rules, so we used the rules to elucidate the 13 other Abs. All Abs consisted of eight amino acids and one hydroxy acid.

Amino Acid Sequence↗
PubMed1998

The effect of glycolic acid on cultured human skin fibroblasts: cell proliferative effect and increased collagen synthesis.

Glycolic acid peeling is known to improve photoaging processes such as wrinkling and roughness, but this effect has not been clearly defined, even though functional activation of fibroblasts has been suggested. The study was aimed to determine the effects of glycolic acid and malic acid (AHA: alpha hydroxy acid) on cultured dermal fibroblasts. Whether it directly increases cell proliferation may be an important factor influencing the production of extracellular matrix such as type I collagen. Cultured human skin fibroblasts were treated for 24 hours with glycolic acid and malic acid at different concentrations (10(-4), 10(-5), 10(-6) M), and cell proliferation was measured by MTT assay. Then quantitative analysis of collagen synthesis was performed by PICP (Procollagen Type I C-peptide) enzyme immunoassay and radioisotope (3H-proline) labelled collagen assay. The results showed increased cell proliferation and collagen production in response to glycolic acid in a dose dependent manner. The range of cell proliferation and collagen production were significantly higher with glycolic acid treatment than with malic acid or control. It was suggested that the favorable effects of glycolic acid treatment on aging skin were mediated by increased cell proliferation in addition to functional activation of fibroblasts.

Cell Division↗
PubMed2006

Histopathological and ultrastructural effects of glycolic acid on rat skin.

Use of alpha hydroxy acids (AHA) to ameliorate specific dermatological problems with keratinization has become fairly widespread. The aim of this study was to evaluate the effects of the AHA derivative of glycolic acid, applied in different dosages, on rat skin using light and electron microscopy. Skin biopsies were taken from the dorsal side of rats (n=16) and at the end of each week after applying solutions containing AHA: week 1, 8% (n=5); week 2, 50% (n=5); week 3, 70% (n=6). The skin samples were fixed in 10% formalin for histology and 2.5% glutaraldehyde solution for electron microscopy and processed using routine protocols. Histological sections were stained with hematoxylin and eosin (H&E), Masson's trichrome and were also labelled for binding of a primary antibody against collagen I using the avidin-biotin-peroxidase method. The epidermal thicknesses were measured and the fibroblast count of the dermis was taken and the results compared using the statistical ANOVA test. Semi-thin sections were stained with toluidine blue-azure II solution and ultrathin sections were contrasted with uranyl acetate and lead citrate. Histochemical and immunohistochemical observations demonstrated that AHA treatment resulted in statistically significant increased thickness of the epidermis and an increase in numbers of active fibroblasts and in the amount of dense collagen, especially at higher dosages of AHA. Ultrastructural examination of rat skin from AHA-treated groups showed cytoplasmic vacuolization in epidermal keratinocytes, intercellular dysjunctions, and increased quantities of organized bundles of collagen fibers in the dermis. The use of AHA in appropriate dosages has been found to play an important role in the treatment of specific skin disorders, however, the harmful effects of use of AHAs at higher concentrations should not be ignored. We conclude that alpha hydroxyl acids have a wide spectrum of use in the field of dermatology but, due to side-effects, their use, dosage, and time frame should be restricted to the advice of dermatologists.

Animals↗
PubMedDate not supplied

NO synthase and guanylate cyclase inhibitors block modulation of the plasticity of common snail cholinoreceptors by 15-hydroxy-eicosatetraenoic acid.

The probable role of two second messengers, nitrogen oxide (NO) and cyclic guanosine monophosphate (cGMP) in the short- and long-latency effects of the acyclic eicosanoid 15(S)-hydroxy-5Z,8Z,11Z,13E-eicosatetraenoic acid (15-HETE) on the plasticity of somatic cholinoreceptors of identified RPa3 and LPa3 neurons of Helix lucorum, was investigated using the two-electrode voltage clamp technique on the membrane. It was demonstrated that N omega-methyl-L-arginine (an inhibitor of NO synthase), LY-83,583 [sic], and the dye methylene blue (inhibitors of soluble guanylate cyclase), when applied extracellularly, disrupt the short- and long-latency modulatory influences of 15-HETE on the depression of the inward current induced by acetylcholine during its rhythmic application to the soma. The participation of NO and cGMP in the modulatory effects of 15-HETE on the plasticity of cholinoreceptors is hypothesized.

Acetylcholine↗
PubMed1992

In vivo transformation of arachidonic acid into 12-hydroxy-5,8,10,14-eicosatetraenoic acid by human nasal mucosa.

A method for the determination of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) by gas chromatography-mass spectrometry (GC-MS) in samples obtained from healthy subjects by nasal lavage is presented. HETEs were extracted from samples obtained by nasal lavage using C18 solid-phase cartridges. The purification of 12-HETE and 5-HETE was carried out in two consecutive steps of purification by reversed-phase high-performance liquid chromatography. Methylated and trimethylsilylated fractions were separated by GC-MS with electron-impact ionization. The production of 12-HETE by human nasal mucosa was confirmed by GC-MS.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1988

Rat kidney L-2-hydroxyacid oxidase. Structural and mechanistic comparison with flavocytochrome b2 from baker's yeast.

Hydroxyacid oxidase from rat kidney is an FMN-dependent enzyme that catalyzes the oxidation of L-alpha-hydroxy acids as well as, more slowly, that of L-alpha-amino acids. We report here a modified purification method for the enzyme, which is found to possess one cofactor per subunit of Mr 39,000. Determination of its N-terminal sequence suggests the protein is homologous to spinach glycolate oxidase and baker's yeast lactate dehydrogenase. In the presence of a hydroxy acid and of bromopyruvate, under anaerobic conditions, the enzyme is found to catalyze both transhydrogenation and reductive bromide ion elimination. It had previously been observed that hydroxyacid oxidase could not catalyze chloride elimination from chlorolactate in the presence of oxygen [Cromartie, T.H., & Walsh, C.T. (1975) Biochemistry 14, 3482-3490]. The behavior of this enzyme toward halogeno substrates is therefore similar to that of baker's yeast L-lactate dehydrogenase and in part different from that of Mycobacterium smegmatis lactate oxidase and porcine kidney D-amino-acid oxidase. These findings can be rationalized on the basis of a common mechanism for all these enzymes, implying formation of a carbanion as a first step, with different rate-limiting steps in the overall reaction.

Alcohol Oxidoreductases↗
PubMed1988

Formation of three types of glucuronides of 6-hydroxy bile acids by rat liver microsomes.

The glucuronidation of 6-hydroxylated bile acids by rat liver microsomes was studied in vitro; for comparison, several major bile acids lacking a hydroxyl group in position 6 were also investigated. The highest reaction rates were found for lithocholic and deoxycholic acid (10.2 +/- 0.2 and 7.3 +/- 1.4 nmol/mg.min, respectively); our results for these substrates agree well with published values. Glucuronidation rates for the 6 beta-hydroxylated bile acids 3 alpha, 6 beta-dihydroxy-5 beta-cholanoate (murideoxycholate) and 3 alpha, 6 beta, 7 beta-trihydroxy-5 beta-cholanoate (beta-muricholate) were only slightly lower (3.7 +/- 0.3 and 3.6 +/- 0.3 nmol/mg.min). 6 alpha-Hydroxylated bile acids were glucuronidated at rates that were lower than those for their 6 beta-hydroxy counterparts. Rigorous product identification by high-field proton NMR of methyl/acetyl derivatives revealed that while bile acids lacking a 6-hydroxyl group gave rise exclusively to the typical 3-O-glucuronide, the presence of a hydroxyl group in position 6 led to the formation, in ratios depending on the substrate, of three types of conjugate: the 3-O-, the 6-O-, and the carboxyl-linked (acyl-) glucurnide. The latter is the first example of an acyl glucuronide of a bile acid of conventional (C24) size.

Animals↗
PubMed1994

Determination of microbial chemical markers by gas chromatography-mass spectrometry--potential for diagnosis and studies on metabolism in situ. Review article.

Different strategies for the application of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) in medical microbiology research are discussed. GC can be used to determine specific microbial monomeric constituents and metabolites, so-called chemical markers, in cultures of microorganisms; in particular, analysis of cellular fatty acids has proven useful for species characterization and identification. GC-MS can be applied to study chemical markers directly in complex environmental samples, as exemplified by the analysis of airborne organic material as regards muramic acid (marker of peptidoglycan), 3-hydroxy acids (endotoxins), and ergosterol (fungal biomass). This methodological approach represents an alternative to various biological assays for characterization of airborne microbial structures, and forms a firm basis for correlating inhalation of such structures and development of symptoms. Direct GC-MS analysis of clinical samples provides possibilities for diagnosis (here exemplified by chiral separation of urine D- and L-arabinitol in disseminated candidiasis) and insight into microbial metabolism in the infected host (exemplified by observed indications of mycobacterial build-up of mycolic acids in vivo), with implications for drug development. Continued developments in MS technology will allow rapid advances to be made in GC-MS research in microbiology.

Bacteria↗
PubMed1980

Cyclic GMP metabolism in psoriasis: activation of soluble epidermal guanylate cyclase by arachidonic acid and 12-hydroxy-5,8,10,14-eicosatetraenoic acid.

Soluble guanylate cyclase activity was measured in normal and psoriatic human epidermis. The specific activity of guanylate cyclase was determined to be increased 10-fold and 3-fold in involved and uninvolved epidermis of psoriatics, respectively, compared to normal epidermis. Arachidonic acid (5 to 100 micrometers) or 12-hydroxy-5,8,10,14-eicosatetraenoic acid (HETE) (5 to 50 micrometers) stimulated guanylate cyclase activity from involved epidermis 2- to 3-fold and from uninvolved epidermis up to 2-fold, but these fatty acids had no effect on the activity of this cyclase from normal epidermis. These results indicate that there is an increase in the cGMP biosynthetic capacity of involved epidermis from psoriatics that derives from a markedly increased specific activity of guanylate cyclase and an alteration in a property of this enzyme activity which renders it responsive to fatty acids reported to accumulate in this lesion. These observations are consistent with the report that an elevated steady-state level of cGMP is one of the consequences of the strikingly altered metabolism of cGMP in psoriatic epidermis.

Arachidonic Acids↗
PubMed1986

Gastrointestinal absorption of neptunium in primates: effect of ingested mass, diet, and fasting.

Absorption and retention of neptunium were determined in baboons after intragastric administration of neptunium nitrate solutions at pH 1. The effects of mass, diet, and fasting on absorption were studied. At higher mass levels (400-800 micrograms Np/kg), absorption was about 1%; at lower mass intakes (0.0009-0.005 micrograms Np/kg), absorption was reduced by 10- to 20-fold. The addition of an oxidizing agent (Fe3+) increased gastrointestinal absorption and supported the hypothesis of a reduction of Np (V) when loss masses were ingested. Diets depleted of or enriched with hydroxy acids did not modify retention of neptunium but increased urinary excretion with increasing hydroxy acid content. The diet enriched with milk components reduced absorption by a factor of 5. Potatoes increased absorption and retention by a factor 5, not necessarily due to the effect of phytate. Fasting for 12 or 24 h increased retention and absorption by factors of about 3 and 10, respectively. Data obtained in baboons when low masses of neptunium were administered suggest that the f1 factor used by ICRP should be decreased. However, fasting as encountered in certain nutritional habits is a factor to be taken into consideration.

Animals↗
PubMed1992

Aminopeptidase inhibitory properties and analgesic activity of (2S,3R)-3,7-diamino-2-hydroxy-heptanoic acid containing tripeptide analogues of the N-terminal tripeptide of probestin.

(2S,3R)-3,7-Diamino-2-hydroxy-heptanoyl-Leu-Pro-OH [(2S,3R)-DAHHA-Leu-Pro-OH, 4], analogue of the N-terminal tripeptide of probestin, has been synthesized, and tested as inhibitor of AP-B, Leu-AP, AP-M, and enkephalin-degrading APs, and as analgesic. In order to establish structure-activity relationships the dipeptide (2S,3R)-DAHHA-Pro-OH (5) and the tripeptide (2S,3R)-DAHHA-Ala-Pro-OH (6) were also prepared. Compounds 4 and 6 were potent and selective inhibitors of enkephalin-degrading APs and showed a prolonged antinociceptive effect.

Aminopeptidases↗
PubMed1993

Structural analysis of hydroxy fatty acids by thermospray liquid chromatography/tandem mass spectrometry.

Thermospray liquid chromatography/tandem mass spectrometry provides a sensitive and convenient technique for the structural analysis of oxygenated polyunsaturates. Analysis of pentafluorobenzyl derivatives in the negative ion mode under the filament- or discharge-on condition generated abundant [M - PFB]- ions. These ions were further fragmented by collision with argon and detected in the negative ion mode. The negative ion fragmentation pattern was examined for various oxygenated polyunsaturated fatty acid standards as well as their deuterated and/or hydrogenated forms. Characteristic fragmentation occurs at the oxygenated C-C bonds, allowing unambiguous determination of the sites of oxygenation. The sample amount required is typically in the low tens of nanogram range. Using this method the structures of epoxy, hydroxy derivatives of 4,7,10,13,16,19-docosahexaenoic acid (22:6w3) formed by soybean lipoxygenase were determined. They were 13-hydroxy-16,17-epoxy-22:5w3 and 15-hydroxy-16,17-epoxy-22:5w3.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1968

Fatty acid composition of brain glycolipids in Alzheimer's disease, senile dementia, and cerebrocortical atrophy.

Quantitative fatty acid compositions are reported for human cerebral gray matter glycolipids (gangliosides, cerebrosides, and cerebroside sulfates) in Alzheimer's disease (presenile dementia) and related disorders of the central nervous system. Although the fatty acid compositions were generally similar to those of the controls, some significant differences were noted in Alzheimer's disease which were not found in the single samples of senile dementia and of senile cerebrocortical atrophy. In the ganglioside fatty acids, the percentage of palmitic acid was higher in all three cases of Alzheimer's disease than in the controls. In cerebrosides, the proportion of 2-hydroxy to non-hydroxy acids was slightly lower in Alzheimer's disease than in controls and the relative proportions of 2-hydroxystearic acid and 2-hydroxytricosenoic acid were slightly higher. In cerebroside sulfates, monounsaturated 2-hydroxy acids were lower in two of the samples with Alzheimer's disease. The results indicate possible effects of the degenerative changes in this disease on glycolipid metabolism.

Aged↗
PubMed1973

Identification of the amide-linked fatty acids of Acholeplasma axanthum S743 as D(-)3-hydroxyhexadecanoate and its homologues.

The amide-linked fatty acids of the sphingolipids of Acholeplasma axanthum S743 are predominantly hydroxy acids. These acids were shown by gas-liquid chromatography, mass spectrometry, and polarimetry to be the d(-)3-hydroxy fatty acids. The predominant component of the mixture was 3-hydroxyhexadecanoate (beta-hydroxypalmitate, hydroxy [h] 16:0) followed by h 20Delta (Delta = unsaturated), h14:0, h12:0, and h18Delta in decreasing order of concentration. The fatty acid profile indicates that these beta-hydroxy acids possibly arise from elongation of the fatty acids supplied in the growth medium.

Bacteria↗