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At least 433 records · Page 24Linked to original sources
PubMed1995

Heparin inhibits the accumulation of re-esterified cholesterol in macrophages loaded with acetylated low-density lipoprotein.

Heparin enhances the endocytosis of low density lipoprotein (LDL) in macrophages via a formation of complex with LDL. The direct effect of heparin on the metabolism of cholesterol in macrophages has not been elucidated. We therefore evaluated the effects of heparin on the accumulation and reesterification of cholesterol in cultured macrophages. We used acetylated LDL (acetyl-LDL), which lacks an affinity for heparin. Rat peritoneal macrophages induced with thioglycollate were incubated with 100 micrograms of acetyl-LDL for 14 h. Heparin significantly inhibited the accumulation of total and esterified cholesterol but did not affect the binding of 125I-labeled acetyl-LDL to macrophages or its cellular degradation. Heparin at concentration above 5 micrograms/ml inhibited the incorporation of [3H]oleate into cholesteryl oleate in macrophages. Heparin significantly inhibited the acyl CoA:cholesterol acyl transferase (ACAT) activity of macrophages by 68%. Data suggest that heparin inhibits the accumulation and reesterification of cholesterol in macrophages loaded with acetyl-LDL. Heparin-like proteoglycans may thus protect the macrophages against the excessive accumulation of esterified cholesterol.

Animals↗
PubMed1972

Metabolism of myricetin and related compounds in the rat. Metabolite formation in vivo and by the intestinal microflora in vitro.

1. The metabolism of a group of polyphenols related in structure to myricetin (3,5,7,3',4',5'-hexahydroxyflavone), including myricetin, myricitrin, 3,4,5-trihydroxyphenylacetic acid, delphinidin, robinetin, tricetin, tricin, malvin and 5,7-dihydroxy-3',4',5'-trimethoxyflavone, has been studied both in vivo after oral administration to the rat and in vitro in cultures of micro-organisms derived from the intestine of the rat. 2. It was shown that the rat intestinal microflora are able to degrade compounds of this group to the ring-fission products observed in urine after oral administration of the specific flavonoid. 3. All flavones and flavonols possessing free 5- and 7-hydroxyl groups in the A ring and a free 4'-hydroxyl group in the B ring gave rise to ring-fission products that included 3',5'-dihydroxyphenylacyl derivatives. 4. The metabolites 3,5-dihydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 3,5-dihydroxyphenylpropionic acid and 3-hydroxyphenylpropionic acid were isolated and identified by chromatographic and spectral methods. 5. On anaerobic incubation in a thioglycollate medium it was shown that intestinal micro-organisms can effect cleavage of glycosidic bonds, ring fission of certain flavonoid molecules showing 3',4',5'-trihydroxyphenyl substitution and dehydroxylation of certain flavonoid metabolites. 6. The urinary excretion of the metabolites 3,5-dihydroxyphenylacetic acid and 3-hydroxyphenylacetic acid was completely abolished when neomycin-treated rats were used.

Animals↗
PubMed1992

Lipopolysaccharide impairs macrophage cytoplasmic pH regulation under conditions simulating the inflammatory microenvironment.

Within the acidic inflammatory milieu, macrophages (m phi s) must maintain their cytoplasmic pH (pHi) within a range conducive to optimal function. It was previously shown that metabolism of L-arginine at concentrations present in vitro in RPMI medium (1.14 mM) impairs the ability of m phi s to regulate pHi. However, concentrations of L-arginine in vivo reportedly range from approximately 100 microM in serum to less than or equal to 50 microM in wounds. To investigate the potential in vivo relevance of this inhibition, m phi pHi regulation was examined following incubation with low concentrations of L-arginine that mimic the inflammatory microenvironment, in the presence or absence of lipopolysaccharide (LPS). pHi regulation was evaluated as the ability of thioglycolate-elicited murine peritoneal m phi s to recover from an imposed cytoplasmic acid load. The m phi pHi was measured using a pH-sensitive fluorescent probe. Following incubation for 2 h in the absence of LPS, the pHi recovery rate was equivalent in cells incubated with and without L-arginine. Coincubation with LPS, however, resulted in marked inhibition of pHi recovery at L-arginine concentrations as low as 12.5 microM. The inhibition was not due to LPS alone, since LPS without L-arginine was not inhibitory. Inhibition of pHi recovery was observed at LPS concentrations ranging from 10 ng/ml to 10 micrograms/ml. The L-arginine-dependent inhibition was apparent within 60 min of exposure to LPS, in both freshly harvested cells and cells preincubated for 2 h in the absence of L-arginine and then exposed to both L-arginine and LPS. Under conditions mimicking the in vivo setting, LPS-stimulated L-arginine metabolism impairs m phi pHi regulation. Modulation of pHi by this mechanism may compromise m phi function within the acidic microenvironment of inflammation.

Animals↗
PubMed1975

Improved growth media for Vibrio succinogenes.

Five new culture media for Vibrio succinogenes are described. Of these, a medium composed of 0.4% yeast extract, 100 mM ammonium formate, 120 mM sodium fumarate, and 0.05% sodium thioglycolate, pH 7.3, supports the best growth.

Asparagine↗
PubMed1966

The extraction and assay of aminoacyl-transfer-ribonucleic acid synthetases of tobacco leaf.

1. Aminoacyl-transfer-RNA synthetase activity in extracts prepared from tobacco leaf was increased 3-5-fold when sodium thioglycollate (30mm) and magnesium chloride (16mm) were included in the extraction medium. Omitting sucrose (0.45m) from the extraction medium did not alter the activity. 2. Activity was a linear function of enzyme concentration up to 1 disk (30mg. fresh wt.)/ml. and was not affected by dialysis at any concentration. 3. Activity increased about 13-fold above control values when a mixture of 21 amino acids and amides (1mm) was added to the reaction mixture. 4. Under the conditions used in the standard assay for aminoacyl-transfer-RNA synthetase activity K(m) (ATP) was 0.65mm and K(m) (l-amino acids) was 70mum. 5. Activity above the control value was found with all amino acids and amides tested except alanine, arginine, glutamic acid, glutamine and hydroxyproline. Activity was highest with leucine, isoleucine, valine, cysteine and histidine. Total activity with a mixture of 21 amino acids and amides was 20% lower than the total activity of the enzymes assayed separately.

Adenosine Triphosphatases↗
PubMed1983

The use of bis(mercaptoacetato-S,O)hydroxoiron(III) complex for the determination of hydroxamates.

A rapid, indirect, spectrophotometric procedure for the determination of hydroxamates, based on the competition for ferric ions of the bis(mercaptoacetato-S,O)hydroxoiron(III) complex, has been developed. The assay is remarkably free of interferences by common ions, thus rendering it useful in the quantitative determination of hydroxamates in culture fluids and crude preparations.

Enterobacter↗
PubMed2000

Capillary electrophoresis analysis of gentamicin sulphate with UV detection after pre-capillary derivatization with 1,2-phthalic dicarboxaldehyde and mercaptoacetic acid.

A selective, sensitive, and rapid pre-capillary derivatization method for determination of the multicomponent aminoglycoside antibiotic gentamicin is described. The derivatization reagents 1,2-phthalic dicarboxaldehyde and mercaptoacetic acid were used and the thioisoindole derivative was UV detected at 330 nm. A central composite experimental design was performed to optimize selectivity and derivatization conditions. Baseline separation of gentamicin C1, C1a, C2, C2a, C2b, sisomicin and several minor components was achieved with a background electrolyte containing 30 mM sodium tetraborate, 7.5 mM beta-cyclodextrin and 12.5% (v/v) methanol at pH 10. Quantitative analysis was performed and illustrated the potential use of capillary electrophoresis for the identification and quantitation of gentamicin as an alternative to methods prescribed in the United States Pharmacopeia and European Pharmacopoeia.

Electrophoresis, Capillary↗
PubMed2002

Effects on the reactive oxygen species of erdosteine and its metabolite in vitro.

Erdosteine (CAS 84611-23-4) and its active metabolite (M1) decrease the luminol-dependent chemiluminescence (LDCL). In this study, the scavenging effects of erdosteine and M1 on each reactive oxygen species, hypochlorous acid (HOCl), hydrogen peroxide (H2O2) and superoxide anion (O2-), were investigated. M1 interacted with HOCl at high activity, whereas erdosteine exhibited low activity. Although erdosteine interacted with H2O2 only at 1 mmol/l, M1 could significantly decrease H2O2 (> 0.1 mmol/l). Erdosteine and M1 did not interact with O2-. These results suggest that M1 possesses scavenging activities against H2O2 and HOCl in vitro.

Acetylcysteine↗
PubMed2001

Mutations that reduce sinapoylmalate accumulation in Arabidopsis thaliana define loci with diverse roles in phenylpropanoid metabolism.

The products of phenylpropanoid metabolism in Arabidopsis include the three fluorescent sinapate esters sinapoylglucose, sinapoylmalate, and sinapoylcholine. The sinapoylmalate that accumulates in cotyledons and leaves causes these organs to appear blue-green under ultraviolet (UV) illumination. To find novel genes acting in phenylpropanoid metabolism, Arabidopsis seedlings were screened under UV for altered fluorescence phenotypes caused by changes in sinapoylmalate content. This screen identified recessive mutations at four Reduced Epidermal Fluorescence (REF) loci that reduced leaf sinapoylmalate content. Further analyses showed that the ref mutations affected other aspects of phenylpropanoid metabolism and some led to perturbations in normal plant development. A second class of mutations at the Bright Trichomes 1 (BRT1) locus leads to modest reductions in sinapate ester content; however, the most notable phenotype of brt1 mutants is the development of hyperfluorescent trichomes that appear to contain elevated levels of sinapate esters when compared to the wild type. These results indicate that at least five new loci affecting the developmentally regulated accumulation of phenylpropanoid secondary metabolites in Arabidopsis, and the cell specificity of their distribution, have been identified by screening for altered UV fluorescence phenotypes.

Alleles↗
PubMed1998

Effect of acidic fibroblast growth factor (aFGF) on phagocytosis in mouse peritoneal macrophages.

The effects of acidic fibroblast growth factor (aFGF) on phagocytosis in peritoneal macrophages from thioglycollate-elicited mice were examined using flow cytometry. aFGF enhanced phagocytosis of fluorescein isothiocyanate-labeled latex particles in a dose-dependent manner. Basic fibroblast growth factor (bFGF) also enhanced phagocytosis. This study suggests that aFGF can modulate an important activity of macrophages.

Animals↗
PubMedDate not supplied

[Acute intoxication by cosmetics].

Intoxications due to cosmetics are of various types, but certain substances may be particularly harmful, especially when the constituants include acetone, boric acid and borates, ethyl alcohol, bromates, formol, methyl alcohol, propylene glycol, thallium, thioglycolate.. Every cosmetic substance may induce accidental intoxications. Most often, fluid cosmetics are absorbed either by children or by feeble-minded subjects. In all intoxication, one must take account of the age and weight of the patient, of the quantity absorbed, of the toxicity and of the constituants of the substance.

Adolescent↗
PubMed1993

The glycosaminoglycans in cultures of stimulated rat peritoneal macrophages. 2. Gel chromatographic studies and the behaviour of heparan sulfate.

The molecular weight distribution of pMP-derived glycosaminoglycans (GAG), i.e. non-sulfated GAG, chondroitin sulfate (CS), and heparin sulfate (HS)-like material was determined. The peritoneal macrophages (pMP) were harvested from rats normal or stimulated by i.p. injection of thioglycolate, carrageenan or BCG, and maintained in culture. The GAG of cell layer and medium were isolated separately after labeling with 35S-sulfate and 3H-acetate. Treatment with nitrous acid served to remove HS-like material. Labeling with 3H-acetate served to detect synthesis of the high m. w. hyaluronic acid (HA). Gel chromatic separation was done using Sephadex G-200 columns. The maximal size of 35S-labeled GAG, especially HS (36 kDa), was reduced in cultural medium and cell layer after stimulation in vivo. Reduction was most pronounced after application of carrageenan followed by thioglycolate and BCG/LPS stimulation. The extracellular GAG of BCG-stimulated pMP were smallest, probably due to degradation. Heparan sulfate-like material made up a larger proportion in monolayer and medium, comprising the total m.w. range up to 36 kDa. The GAG sensitive to nitrous acid were maximal in cultures of carrageenan-stimulated pMP and minimal in those of thioglycolate-stimulated pMP. This type of HS was sensitive to hyaluronidase, too. Any synthesis of high molecular hyaluronic acid was not found in normal or stimulated rat pMP. Therefore MP-associated HA must be adsorbed from other sources or synthesized by early forms of macrophages.

Animals↗
PubMed1991

Nitric oxide derived from L-arginine impairs cytoplasmic pH regulation by vacuolar-type H+ ATPases in peritoneal macrophages.

The ability of macrophages (Møs) to function within an acidic environment has been shown to depend on cytoplasmic pH (pHi) regulation by vacuolar-type H+ ATPases. Møs metabolize L-arginine via an oxidative pathway that generates nitric oxide, nitrate, and nitrite. Since each of these products could potentially inhibit vacuolar-type H+ ATPases, we investigated the effect of L-arginine metabolism on Mø pHi regulation in thioglycolate-elicited murine peritoneal Møs. H+ ATPase-mediated pHi recovery from an imposed cytoplasmic acid load was measured fluorometrically. When Møs were incubated with L-arginine (0.25-2.0 mM), their rate of pHi recovery declined progressively from 2 to 6 h of incubation. By contrast, the recovery rate of cells incubated in arginine-free medium remained stable over the same period. The impairment of pHi recovery was specific for L-arginine, and was blocked competitively by NG-monomethyl-L-arginine, demonstrating its dependence on L-arginine metabolism. In addition, the inhibition of pHi recovery was enhanced by lipopolysaccharide, an agent known to stimulate L-arginine metabolism by Møs. Scavenging the L-arginine metabolite nitric oxide with either ferrous sulphate or ferrous myoglobin prevented the inhibition of pHi recovery, implying that L-arginine-derived nitric oxide was the species responsible for the inhibition. This concept was supported by the finding of elevated nitrite levels in the supernatant of cells incubated in L-arginine. Furthermore, incubation of Møs with sodium nitroprusside mimicked the L-arginine-dependent inhibition of H+ ATPase activity. Treatment with the cyclic GMP analogue, 8-bromoguanosine 3':5'-cyclic monophosphate, similarly impaired Mø pHi recovery, suggesting that a nitric oxide-stimulated elevation of cyclic GMP may contribute to the L-arginine-dependent inhibition of pHi regulation.

Acid-Base Equilibrium↗
PubMed1994

Water soluble complexes of C14 and C16 fatty acids and alcohols in media for cultivation of leprosy-derived psychrophilic mycobacteria.

Host-grown Mycobacterium leprae cell suspensions oxidized water-soluble complexes of palmitic acid, myristic acid, cetyl alcohol, and myristyl alcohol prepared with randomly methylated-beta-cyclodextrin as host molecules. Gas chromatography analysis showed that the water-soluble complexes retained their chemical structure following sterilization in the autoclave. Bioavailability of the two long-chain fatty acids and the corresponding long-chain alcohols was confirmed by Warburg manometric techniques with host-grown M. leprae cell suspensions. Inoculated with host-grown M. leprae cells in chemically well-defined, simple liquid and agar media, acid-fast bacilli were cultivable in primary cultures and subcultures at 10 degrees C with (NH4)2SO4 as the N source and water-soluble palmitic acid, myristic acid, cetyl alcohol or myristyl alcohol as the C and potent energy sources. M. phlei oxidized the complexed palmitic acid and myristic acid but not cetyl alcohol or myristyl alcohol. On agar media with any of these four carbon sources and (NH4)2SO4 but not ammonium thioglycolate as the N source, M. phlei grew abundantly at 36 degrees C. In liquid media only myristyl alcohol supported growth of M. phlei without any growth with palmitic acid, cetyl alcohol or myristic acid. The leprosy-derived, cold-loving cultures ("M. psychrophilum") were not fully tested for classification and identification. The cells are strongly acid-fast facultative psychrophiles, adapted in subcultures to mesophilic growth. They grow in chemically well-defined media with 14 and 16 C long-chain fatty acids or alcohols as the C and energy sources. None of the cultures grow on Low-enstein or 7H9 media. Heat-killed suspensions of the 4th and 6th subcultures provoke Mitsuda-type late skin reactions in tuberculoid, borderline and borderline-tuberculoid but not in lepromatous leprosy volunteers. When grown with (NH4)2SO4 as the N source (but not with the reducing agent ammonium thioglycolate) the subcultures multiplied abundantly in the foot pads of mice. It became evident that leprosy-derived, facultative psychrophilic mycobacteria really exist. Mycobacteria of this cluster do not distinguish between 14 or 16 C long chains with COOH or CH2OH as terminal bindings. Cells are quite aerophilic and grow preferentially on agar slant surfaces.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗