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PubMed2001

Alginate formation in Azotobacter vinelandii UWD during stationary phase and the turnover of poly-beta-hydroxybutyrate.

Azotobacter vinelandii UWD is a mutant of strain UW that is defective in the respiratory oxidation of NADH. This mutation causes an overproduction of polyhydroxyalkanoates (PHAs), as polyester synthesis is used as an alternative electron sink. Since PHAs have potential for use as natural, biodegradable plastics, studies of physiology related to their production are of interest. Alginate production by this strain is limited to < 11 microg (mg cell protein)(-1), which permits high efficiency conversion of carbon source into PHA. However, < or = 400 microg (mg cell protein)(-1) was formed when UWD cells were oxygen-limited and in the stationary phase of growth. Alginate formation was fuelled by PHA turnover, which was coincident with the synthesis of alkyl resorcinols, under conditions of exogenous glucose limitation. However, alginate production was a phenotypic and reversible change. Alginate production was stopped by interruption of algD with Tn5lacZ. LacZ activity in UWD was shown to increase in stationary phase, while LacZ activity in a similarly constructed mutant of strain UW did not. Transcription of algD in strain UWD started from a previously identified RpoD promoter and not from the AlgU (RpoE) promoter. This is because strain UWD has a natural insertion element in algU. Differences between strain UW and UWD may reside in the defective respiratory oxidation of NADH, where the NADH surplus in strain UWD may act as a signal of stationary phase. Indeed, a backcross of UW DNA into UWD generated NADH-oxidase-proficient cells that failed to form alginate in stationary phase. Evidence is also presented to show that the RpoD promoter may be recognized by the stationary phase sigma factor (RpoS), which may mediate alginate production in strain UWD.

Alginates↗
PubMed1972

Photoconversion of riboflavin to lumichrome in plant tissues.

Free flavins have been extracted from shoots of etiolated corn (Zea mays L., var. Burpee Snowcross) and from yeast cells and separated from other substances by absorption on resorcinol-formaldehyde resin and talc columns and by thin layer chromatography. Riboflavin was the only free flavin present. Extracts of etiolated shoots of oats (Avena sativa L., var. Multiline E-69 and Clinford) yielded riboflavin plus a second free flavin previously demonstrated in oats. The areas of the chromatograms expected to contain lumichrome were completely clear. After illumination of any of the three organisms with artificial light (1100 ft-c) or sunlight for 6 hours, lumichrome (7,8-dimethylalloxazine) was found. In corn shoots after irradiation by sunlight, the amount of lumichrome present was equivalent to 2.5% of the total free flavin. Lumichrome was identified by thin layer chromatography in six solvent systems (including two two-dimensional systems), by its characteristic fluorescence in acetic acid, by its absorption spectrum, and by formation of a characteristic hydrate in ammonia-containing solutions. A comparison was made with in vitro photolysis of riboflavin and the possible role of photolysis of riboflavin (either free or bound) and of lumichrome formation in photo-responses of plants is discussed. Placing the shoots in the dark for 4 hours after irradiation in sunlight for 6 hours led to no detectable loss of the lumichrome which had been formed.

Journal Article↗
PubMed1982

Oxidation of reduced pyridine nucleotide by a system using ascorbate and hydrogen peroxide from plants and algae.

A NAD(P)H oxidizing system (NAAP) was detected and partially purified from leaves of spinach and Sedum praealtum, seeds and leaves of pea and cells of green and red algae which oxidized NAD(P)H in the presence of ascorbate and H(2)O(2).The partially-purified spinach system had substrate K(m) values of 5 micromolar for NADH, 50 micromolar for H(2)O(2), and 300 micromolar for l-ascorbic acid at the pH optimum of 6.8. NADH was a better electron donor than NADPH. Among other electron donors, isoascorbic acid had considerable activity but hydroquinone and resorcinol had only weak activities. The enzyme was inhibited by cyanide, alpha,alpha'-dipyridyl, and mono-and di-thiol reagents. Inhibition by thiol-reagents was partially restored by Fe(2+) as was enzymic activity lost following dialysis against buffer.Subcellular localization studies with spinach and S. praealtum leaves indicated that a portion of the cell's NAAP was in the chloroplast fraction. Photosynthetic conditions resulted in a decrease in this activity solubilized from spinach and S. praealtum chloroplasts. The presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea or Fe(2+) in the incubation medium eliminated the light-mediated inhibition of NAAP.NAAP may function in the recycling of NAD(P)H generated in the dark within the chloroplast. Inasmuch as all preparations of NAAP contained ascorbate peroxidase activity, the data do not rule out the possibility that NAAP is the same protein as ascorbate peroxidase or, alternatively, a combination of ascorbate peroxidase and some other enzyme.

Journal Article↗
PubMed1996

Human melanoma cell lines deficient in GD3 ganglioside expression exhibit altered growth and tumorigenic characteristics.

We have selected GD3-deficient human melanoma cell lines, in order to investigate the function of GD3 ganglioside. This was done by treating SK-MEL-28 cells with anti-GD3 antibody (R24) and rabbit complement and subsequent subcloning of the surviving cells, resulting in the derivation of two cell lines deficient in the cell surface expression of GD3. Neither cell line (designated SK-MEL-28-N1 and SK-MEL-28-N2) had detectable cell surface expression of GD3 as analyzed with monoclonal antibody R24, and no GD3 was detectable in either cell line by glycolipid isolation, thin-layer chromatography, or resorcinol-HC1 spray, but thin-layer chromatography immunostaining with monoclonal antibody R24 showed the presence of low amounts of GD3 in both N1 and N2 (1/40 of the amount in the parent cell line in N1 and 1/500 in N2). In SK-MEL-28-N1, the residual GD3 was shown by immunofluorescence assays on permeabilized cells to be present in discrete intracellular organelles, suggesting that these cells have a defect in the transport of GD3 as well as in its synthesis. Both SK-MEL-28-N1 and -N2 had an increase in detectable GM3 expression. The mutant cell lines had altered cell morphology in comparison to the parent cell line and both had slower growth rates in vitro and lower tumorgenicity in nu/nu mice. These results indicate that GD3 ganglioside plays an important role in proliferation and growth of melanoma cells.

Animals↗
PubMed1997

Effect of tea polyphenols on histamine release from rat basophilic leukemia (RBL-2H3) cells: the structure-inhibitory activity relationship.

We studied the effect of tea polyphenols on histamine release from rat basophilic leukemia (RBL-2H3) cells. Among tea polyphenols, (-)- epigallocatechin gallate (EGCG) most strongly and dose-dependently inhibited histamine release from cells stimulated with a calcium ionophore, A23187. (-)-Epigallocatechin (EGC) and (-)-epicatechin gallate (ECG) with a triphenol residue moderately inhibited histamine release, whereas diphenolic (+)-catechin (C) and (-)-epicatechin (EC) did not. The magnitude of the inhibitory effect was in the order EGCG > ECG > EGC. Among simple polyphenols, the triphenol compounds, pyrogallol (PG) and gallic acid (GA) exerted inhibitory activity, but the diphenols, pyrocatechol, hydroquinone, and resorcinol did not. In addition, the mixture of PG and GA inhibited histamine release as strongly as EGCG with two triphenol residues. Similarly, they inhibited histamine release induced by IgE-antigen complex stimulation more efficiently than that induced by A23187 stimulation. EGCG did not inhibit the increase of intracellular Ca2+ in RBL-2H3 cells stimulated with A23187 or IgE antigen. These results indicate that the triphenol structure plays an important role in the inhibitory activity of tea polyphenols. Their activity seemed to be exerted through the metabolic events occurring after the elevation of intracellular Ca2+ concentration.

Animals↗
PubMed1986

Infantile type of sialic acid storage disease with sialuria.

We describe a male infant of Austrian ancestry, the main clinical features including attacks of dyspnea due to laryngomalacia, severe mental and motor retardation, pronounced splenohepatomegaly and vacuolisation of peripheral lymphocytes. The clinical condition deteriorated progressively and the child died at the age of 21 months. Phase and electron microscopy of cultured skin fibroblasts showed multiple vacuoles and inclusions suggestive of a lysosomal storage disorder. Increased excretion of free sialic acid was demonstrated by resorcinol staining after routine thin-layer screening for urinary oligosaccharides. Quantitative analyses of urine, leucocytes and cultured fibroblasts revealed 10 to 30-fold increased concentration of free sialic acid. In addition, 3-fold elevated amounts of sialyloligosaccharides were found in the urine. The activities of a variety of lysosomal enzymes, including sialidase, were normal. Our case is compared with infantile sialic acid storage disease recently observed by other authors. The close convergence of clinical, morphological and biochemical signs support the concept of a distinct lysosomal disease entity. The basic defect is so far unknown.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1988

Practical preparation and deblocking conditions for N-alpha-(2-(p-biphenylyl)-2-propyloxycarbonyl)-amino acid (N-a-Bpoc-Xxx-OH) derivatives.

Reproducible preparations are given for salts of the following L-amino acid derivatives: Bpoc-Ala-OH, Bpoc-Arg(Mtr)-OH, Bpoc-Asn-OH, Bpoc-Asp(OtBu)-OH, Bpoc-Cys(Acm)-OH, Bpoc-Cys(S-tBu)-OH, Bpoc-Gln-OH, Bpoc-Glu(OtBu)-OH, Bpoc-Gly-OH, Bpoc-Ile-OH, Bpoc-Leu-OH, N-alpha-Bpoc-Lys(epsilon-Boc)-OH, Bpoc-Met-OH, Bpoc-Phe-OH, Bpoc-Pro-OH, Bpoc-Ser(OtBu)-OH, Bpoc-Thr(OtBu)-OH, Bpoc-Tyr-OH, Bpoc-Val-OH. A study of the deblocking of N-alpha-Bpoc peptides in dichloromethane containing 0.5% trifluoroacetic acid revealed that a rapid equilbrium is established between the first-formed monomeric alkene 2-p-biphenylylpropene and the hindered dimer 2,4-bis(p-biphenylyl)-4-methyl-1-pentene. Thioethers were found to be inefficient carbocation scavengers for the deblocking reaction. The most efficient scavengers were found to be thiophenol and benzyl mercaptan, and the following approximate reactivity order was established: benzyl mercaptan approximately thiophenol greater than indole much greater than 1,3-dimethoxybenzene approximately resorcinol greater than 1,3,5-trimethoxybenzene approximately dimethyl sulfide approximately thioanisole.

Amino Acids↗
PubMed1990

Problems associated with use of the benzyloxymethyl protecting group for histidines. Formaldehyde adducts formed during cleavage by hydrogen fluoride.

The use of N alpha-tert.-butyloxycarbonyl-N pi-benzyloxymethylhistidine in peptide synthesis resulted in significant levels of several different side products attributable to the generation of formaldehyde during the hydrogen fluoride cleavage reaction. Methylated impurities in a decapeptide were isolated and identified. These methylated impurities were attributed to the use of the benzyloxymethyl protecting group for the histidines, since the impurities did not form when the dinitrophenyl protecting group was used. Also, peptides containing benzyloxymethyl-protected histidines in addition to N-terminal cysteines quantitatively yielded their respective N-terminal thiazolidine derivatives upon isolation from standard hydrogen fluoride cleavage mixtures. Thiazolidine ring formation was circumvented by including in the cleavage reaction a formaldehyde scavenger such as cysteine hydrochloride or resorcinol.

Amino Acid Sequence↗
PubMed1993

Effect of proglycosyn and other phenolic compounds on glycogen metabolism in isolated hepatocytes. Potential role of glucuronidated metabolites.

The mechanism by which proglycosyn (LY 177,507) stimulates glycogen synthesis in isolated hepatocytes [Harris, R. A., Yamanouchi, K., Roach, P. J., Yen, T. T., Dominiani, S. J. & Stephens, T. W. (1989) J. Biol. Chem. 264, 13674-13680] has been investigated. When incubated in the presence of hepatocytes, proglycosyn was metabolized to an O-demethylated glucuronidated derivative, as determined by fast-atom-bombardment mass spectrometry and enzymic analysis. This metabolite accumulated almost linearly inside the cells to reach a concentration of approximately 3 mumol/g protein after 50 min, without apparent release into the medium. In confirmation of previous work, proglycosyn decreased the level of phosphorylase a and increased that of synthase a in hepatocytes. Washing of cells incubated with proglycosyn for 30 min considerably decreased the concentration of the drug without significantly modifying the intracellular concentration of the metabolite and the activation state of glycogen synthase. Several compounds bearing structural analogy with proglycosyn were also tested for their effect on glycogen metabolism. At millimolar or submillimolar concentrations, resorcinol, m-anisidine, phenol, 3-hydroxyacetophenone, and 3-acetamidophenol, although not 4-acetamidophenol, stimulated the incorporation of [14C]glucose into glycogen, decreased the level of phosphorylase a and increased the level of synthase a. In the case of phenol, the effect on the glycogen enzymes paralleled the intracellular accumulation of phenylglucuronide. Furthermore, ethanol and D-galactosamine, which decreased the conversion of phenol to phenylglucuronide and the intracellular concentration of phenylglucuronide, counteracted the effect of phenol on the synthase and on the phosphorylase. From these results, it is suggested that the effect of proglycosyn and of simpler phenol derivatives is mediated by glucuronidated metabolites, which act on an intracellular target.

Animals↗
PubMed1997

Anaerobic metabolism of aromatic compounds.

Aromatic compounds comprise a wide variety of low-molecular-mass natural compounds (amino acids, quinones, flavonoids, etc.) and biopolymers (lignin, melanin). They are almost exclusively degraded by microorganisms. Aerobic aromatic metabolism is characterised by the extensive use of molecular oxygen. Monoxygenases and dioxygenases are essential for the hydroxylation and cleavage of aromatic ring structures. Accordingly, the characteristic central intermediates of the aerobic pathways (e.g. catechol) are readily attacked oxidatively. Anaerobic aromatic catabolism requires, of necessity, a quite different strategy. The basic features of this metabolism have emerged from studies on bacteria that degrade soluble aromatic substrates to CO2 in the complete absence of molecular oxygen. Essential to anaerobic aromatic metabolism is the replacement of all the oxygen-dependent steps by an alternative set of novel reactions and the formation of different central intermediates (e.g. benzoyl-CoA) for breaking the aromaticity and cleaving the ring; notably, in anaerobic pathways, the aromatic ring is reduced rather than oxidised. The two-electron reduction of benzoyl-CoA to a cyclic diene requires the cleavage of two molecules of ATP to ADP and P1 and is catalysed by benzoyl-CoA reductase. After nitrogenase, this is the second enzyme known which overcomes the high activation energy required for reduction of a chemically stable bond by coupling electron transfer to the hydrolysis of ATP. The alicyclic product cyclohex-1,5-diene-1-carboxyl-CoA is oxidised to acetyl-CoA via a modified beta-oxidation pathway; the ring structure is opened hydrolytically. Some phenolic compounds are anaerobically transformed to resorcinol (1,3-dihydroxybenzene) or phloroglucinol (1,3,5-trihydroxybenzene). These intermediates are also first reduced and then as alicyclic products oxidised to acetyl-CoA. This review gives an outline of the anaerobic pathways which allow bacteria to utilize aromatics even in the absence of oxygen. We focus on previously unknown reactions and on the enzymes characteristic for such novel metabolism.

Acyl Coenzyme A↗
PubMed1981

Interspecies comparison of brain ganglioside patterns studied by two-dimensional thin-layer chromatography.

Brain gangliosides from four vertebrate classes (fish, amphibia, aves, and mammalia) were studied by patterns generated with the use of two-dimensional thin-layer chromatography. In an effort to retain possible alkalilabile gangliosides, samples were not base-hydrolyzed. Resultant chromatograms revealed complex patterns of the major known gangliosides and a number of minor and trace molecular species previously unresolved. More than 30 resorcinol-positive components were detected in mammalian neural samples. Our data indicate both qualitative and quantitative differences in the chromatogram patterns between the vertebrate classes, but potentially greater qualitative similarity exists between the lower and higher classes than has previously been noted.

Animals↗
PubMed1984

Binding of tetanus toxin to somatic neural hybrid cells with varying ganglioside composition.

125I-labelled tetanus toxin interaction with several somatic hybrid cell lines was investigated. Binding of toxin is most effective in NCB-20, followed by NBr-10A, NG108-C15, and SB21-B1 cells. Specific binding of toxin to NCB-20 and SB21-B1 cells is 7- and 60-fold lower, respectively, in comparison to enriched rat cerebral neuron cultures. The NCB-20, NBr-10A, and NG108-C15 clones display a complex ganglioside pattern, including the presence of [N-acetyl-neuraminyl]-galactosyl-N-acetylgalactosaminyl[ N-acetylneuraminyl]-galactosylglucosyl-ceramide (GD1a) and two unidentified [14C]galactose-labelled lipid-soluble compounds, while the SB21-B1 is most abundant in [N-acetyl-neuraminyl]-galactosylglucosyl-ceramide (GM3) and N-acetyl-galactosaminyl-[N-acetyl-neuraminyl]-galactosylglucosyl-c eramide (GM2) gangliosides. None of the cells tested contain measurable levels of [14C]galactose-labelled or resorcinol-positive bands of galactosyl-N-acetyl-galactosaminyl-[ N-acetylneuraminyl-N-acetylneuraminyl]-galactosylglucosyl-ceramide (GD1b) and [N-acetylneuraminyl]-galactosyl-N-acetylgalactosaminyl-[ N-acetylneuraminyl-N-acetylneuraminyl]-galactosylglucosyl-ceramide (GT1b) gangliosides. After 2 h at 37 degrees C a near plateau of toxin association with NCB-20 cells is seen. Binding in low-ionic-strength medium is 1.35-fold higher at 37 degrees C than at 4 degrees C, but is reduced by 21 and 51% at 4 degrees C and 37 degrees C, respectively, in physiologic medium. Treatment of NCB-20 cells with neuraminidase causes a partial loss (29%) of toxin-binding sites. Binding to the hybrid cells is significantly different from that of cerebral cultures with respect to temperature, salt effect, and sensitivity to neuraminidase, suggesting perhaps a different class of receptors for the toxin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Nerve growth factor enhances the expression of the cholinergic-specific ganglioside Chol-1 in cocultures of rat septum and hippocampus.

Cocultures of septal and hippocampal tissues taken from 6- to 7-day-old rats were maintained in culture for up to 30 days in the presence and absence of nerve growth factor (NGF), and their Chol-1 contents determined at varying time intervals by a modified enzyme-linked immunosorption assay (ELISA). The major brain gangliosides were determined densitometrically after spraying chromatograms with resorcinol reagent. There was little change in the contribution of the major gangliosides to the total ganglioside content of the explants either with time or the presence or absence of NGF, the only exception being an NGF-insensitive fall in the contribution of GM1 to about 60% of its initial value at 20 and 30 days. By contrast, the concentration of Chol-1 expressed either per unit weight of ganglioside sialic acid or protein increased considerably in culture and this increase was enhanced by NGF. The effect of NGF resembles that on other cholinergic markers, choline acetyltransferase and acetylcholinesterase, and may be attributed to an NGF-stimulated hippocampal ingrowth of cholinergic fibres and enhanced survival of cholinergic septal neurons. The Chol-1 concentration finally attained in the presence of NGF and the time course of its increase parallel those previously found in vivo and indicate the potential usefulness of septal-hippocampal cocultures for investigating the function of Chol-1.

Animals↗
PubMed2006

Superficial chemical peels.

Superficial chemical peeling (SCP) involves the application of a peeling agent to the skin, resulting in destruction of part or all of the epidermis. SCP is mainly recommended for facial rejuvenation, photoaging and superficial rhytides, pigmentary dyschromias and acne. It can be used on all Fitzpatrick skin types, no sedation is needed, and the desquamation is usually well accepted. Overpeel and complications are very rare. The most commonly used SCP agents are glycolic acid 20-70%, trichloroacetic acid 10-35%, Jessner's solution, salicylic acid, pyruvic acid, resorcinol 30-50% preparations, and solid carbon dioxide. The careful selection of patients is critical for the outcome of a SCP and contraindications must be seriously considered. The peel procedure is generally common for all SCP agents but a good knowledge of the specific characters of each agent is of great importance in order to decide which to use for each individual patient.

Chemexfoliation↗
PubMed1998

Salicylic acid peels for the treatment of photoaging.

Several chemical agents are currently used to perform superficial chemical peels of the face. These include trichloracetic acid (15-30%), alpha-hydroxy acids (e.g., glycolic acid, 40-70%), and Jessner's solution (14% lactic acid, 14% resorcinol, and 14% salicylic acid). We have developed salicylic acid, a beta-hydroxy acid, at a higher strength (30% in a hydro-ethanolic vehicle) as an alternative peel. This peel has distinct advantages for resurfacing moderately photodamaged facial skin. We have peeled patients singly and multiply at 4-week intervals. The benefits are fading of pigment spots, decreased surface roughness, and reduction of fine lines.

Adult↗
PubMed1985

Antibody to glycolipid in a patient with IgM paraproteinemia and polyradiculoneuropathy.

Serum from a patient with IgM paraproteinemia and polyradiculoneuropathy, diagnosed as malignant lymphoma reacted specifically with a lipid component in a crude ganglioside fraction isolated from human peripheral nerve, but did not react with myelin proteins including myelin-associated glycoprotein (MAG). The reactive glycolipid migrated between GM1 and GD1a gangliosides on TLC, and there was no distinct band corresponding to this glycolipid on examination with resorcinol reagent. Antibody to glycolipid in this case may play a role in the pathogenesis of neuropathy.

Aged↗
PubMed1986

Contact dermatitis from Grevillea 'Robyn Gordon'.

Grevillea 'Robyn Gordon' is an Australian hybrid plant which may cause allergic contact dermatitis. Over the past 8 years, it has been planted extensively in Australia and is now being exported to the United States and other Western countries. Recently, an explosion in incidence of contact dermatitis due to this plant has been seen. 24 patients who were suspected of being sensitive to it were patch tested to fresh plant and extracts with confirmation of sensitivity. A cross sensitivity to Toxicodendron was demonstrated clinically and on patch testing. The allergen in Toxicodendron, 3 pentadecylcatechol, is closely linked in chemical structure to 5-pentadecylresorcinol, present in Grevillea banksii and tridecylresorcinol in Grevillea robusta. Patch testing in patients sensitive to Grevillea 'Robyn Gordon' with tridecylresorcinol produced positive reactions, thus implicating the sensitizing rôle of long chain alkyl resorcinols in Grevillea 'Robyn Gordon' allergy. There is a likelihood that this sensitizing potential extends to other plants of the Grevillea genus, e.g., Grevillea robusta. With the spread of Grevillea 'Robyn Gordon' to other markets, this problem will become increasingly common.

Adult↗
PubMed1986

Dermatitis from phenyl salicylate in safety spectacle frames.

We report 3 cases of allergic contact dermatitis behind the ears from wearing the same brand of industrial safety spectacles. In each case, a positive patch test was obtained with scrapings of the plastic frame. In 2 cases further patch tests with constituents of the plastic were carried out; positive patch tests were obtained with phenyl salicylate. Phenyl salicylate is used as an ultraviolet inhibitor in some cellulose acetate butyrate and cellulose acetate propionate formulae. It has previously been reported as a contact sensitizer from its use as a sun screen in a lip salve. Positive patch test reactions were also obtained variously in these patients with balsam of Peru, resorcinol monobenzoate, and epoxy resin.

Adult↗