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Results for “LEVULINIC ACID”

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At least 217 records · Page 12Linked to original sources
PubMed1989

Induction of pulmonary and hepatic cytochrome P-450 species by coal fly ash inhalation in rats.

The effect of fly ash inhalation on xenobiotic metabolizing enzymes and heme metabolism in lung and liver has been studied in rats. Fly ash inhalation induced pulmonary and hepatic cytochrome P-450 content, aryl hydrocarbon hydroxylase and glutathione S-transferase activity. Induction of cytochrome P-450 was accompanied by induction of delta-amino levulinic acid synthetase in lung and inhibition of heme oxygenase in both lung and liver. Fly ash inhalation induced those species of cytochrome P-450 which closely resembled cytochrome P-448 in spectral properties and electrophoretic mobility.

5-Aminolevulinate Synthetase↗
PubMed1992

The effect of EDTA and serum on endogenous porphyrin accumulation and photodynamic sensitization of human K562 leukemic cells.

The interrelationship between the effect of serum on the induction of porphyrin synthesis, intracellular porphyrin accumulation and photodynamic sensitization of human K562 cells is described. Endogenous porphyrins, synthesized from supplemented 5-amino levulinic acid (5-ALA), were shown to accumulate in the cells, while an addition of serum triggered porphyrin translocation from the cell to the serum. In order to enhance porphyrin accumulation in the cells themselves, they were further stimulated by EDTA, which in combination with 5-ALA reduces Fe++ cellular content. The higher porphyrin cellular content under EDTA and 5-ALA induction was exploited to photoinactivate the human leukemic cells by more then 3 orders of magnitude.

Aminolevulinic Acid↗
PubMed1991

In vitro effect of cyanide, thiosulphate and S-adenosyl-L-methionine on the activity of rhodanese and other enzymes.

1. Some in vitro studies were performed to elucidate the action of S-adenosyl-L-methionine (SAM) and thiosulphate on liver rhodanese, delta-amino-levulinic acid dehydratase (Al A-D) and cytochrome oxidase affected by cyanide in the experimental conditions. 2. SAM was unable to interact with the sulfur substituted rhodanese complex suggesting that SAM would blockade the thiosulphate binding sites on rhodanese. 3. Cyanide and thiosulphate inhibited ALA-D activity when both compounds were present in the incubation or the preincubation mixture. Cyanide binding on the enzyme was irreversible. 4. Cyanide inhibited cytochrome oxidase activity and the reversible nature of the binding was demonstrated by gel filtration. 5. SAM had no effect on either ALA-D or cytochrome oxidase activities.

Animals↗
PubMed1981

Effect of lead and zinc administration on liver, kidney and brain levels of copper, lead, manganese and zinc and on erythrocyte ALA-D activity in rats.

Albino male rats were given lead (Pb) and zinc (Zn) orally, singly or in combination, for 14 consecutive days. Liver Pb was increased and liver manganese (Mn) was decreased in animals receiving Pb. The combination of Pb and Zn led to increased Pb and decreased copper (Cu) and Mn. Kidney Zn was increased in rats given Zn or the combination of Pb and Zn. There were no changes in kidney Cu or Mn in any group. Brain Pb levels were significantly increased in animals given Pb and Zn levels in those given Zn. Erythrocytic amino levulinic acid dehydratase (ALA-D) activity was significantly decreased by Pb but not by Pb + Zn.

Animals↗
PubMed2005

Establishment and characterization of a new erythroblastic leukemia cell line, EEB: phosphatidylglucoside-mediated erythroid differentiation and apoptosis.

A new erythroblastic leukemia cell line (EEB) was established from a patient with early erythroblastic leukemia. The cells had features of immature erythroblasts, including an agranular basophilic cytoplasm and CD36, CD71, CD175s (sialyl-Tn) and CD235a (glycophorin A) expression without CD41 expression, myeloperoxidase activity and platelet-peroxidase activity. The cells were confirmed to be of the erythroid lineage based on expression of the gamma-globin message. They were induced to differentiate into benzidine-positive cells by hemin and delta-amino levulinic acid (delta-ALA). An analysis of cell membrane lipids showed that EEB cells contain a type of glycerolipid, phosphatidylglucose (PhGlc), but not unbranched type 2 chains, i antigens. GL-7 which is a recombinant Fab fragment of GL-2 and binds to PhGlc, induced production of hemoglobin F (HbF) associated with accumulation of the gamma-globin (gamma-globin) message in EEB cells. The GL-7-mediated erythroid differentiation was associated with apoptosis. These results suggest that direct signaling to PhGlc mediates erythroid differentiation and apoptosis in EEB cells.

Apoptosis↗
PubMed1997

Two periods of sensitivity to mutagens in induced Mel cells with different outcomes.

Mouse erythroleukemia (Mel) cells are particularly sensitive to mutagenic agents between 18 and 24 h from the start of induction (Foresti, M.L. Gaudio, G. Geraci and P. Manduca (1986) Inhibition of dimethyl sulfoxide induced erythropoietic differentiation of murine erythroleukemia cells in culture. Cancer Res., 46, 6260-6263). We show here the occurrence of another period of sensitivity during the initial 5 h after the addition of the inducer dimethyl sulfoxide (DMSO) to the culture medium. The sensitivity to the mutagenic action of a sublethal 3-s pulse of UV light (13.5 J/m2) was monitored on the progeny of the irradiated cells at day 5 after the start of induction. The effects were analysed on functions strictly linked to the final expression of the differentiated phenotype: hemoglobin concentration, percent cells producing hemoglobin (%B+), activity of delta-amino levulinic acid dehydrase (ALA-DH) and presence of globins. Each function appeared differently and selectively affected in the progeny of the cells depending on the exact time of irradiation during the period of sensitivity Specifically, cells irradiated at hour 3 after induction show both hemoglobin concentration and ALA-DH activity values increased by a factor 3 over controls. Cells irradiated at hour 5 show an almost complete halt in cell induction and the other tested functions show minimal values. Cells are nearly insensitive to irradiation at later times, until hour 20, after which a second period of sensitivity with peak value at hour 22 occurs at which time hemoglobin concentration in the progeny of irradiated cells is increased by a factor 3 over controls, ALA-DH activity is increased by a factor 15 while percent B+ value is at its minimum. The differential effects of UV irradiation on Mel cell functions in the first and in the second period of sensitivity to mutagens confirm the hypothesis that the consequences of a mutational event are strictly dependent on the functional state of the cell. The 1-5 h period of sensitivity in which Mel cells fix the effects of the mutagen in their genome corresponds to increased thymidine incorporation not correlated with cell duplication.

Animals↗
PubMed1996

Different treatment modalities for the management of a patient with the nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma (BCC) syndrome is a genetically linked disorder characterized by multiple BCCs associated with various skeletal abnormalities and sometimes with mental retardation. Because of the large number of lesions, treatment of BCCs in these patients may be extremely difficult. The value of different therapeutic options was assessed in a patient with multiple, disfiguring nevoid BCC syndrome. Surgical excision and split-skin grafting was used to remove three larger tumors. Photodynamic therapy led to healing of flat lesions; small papules within the treated areas, however, did not respond to this type of management. Three nodular BCCs treated with intralesional application of interferon alfa-2b were markedly reduced in size. Still, complete healing could not be achieved. Nodular lesions vaporized with the CO2 laser disappeared and showed no recurrence after 2 years of follow up. Our experience indicates that CO2 laser vaporization of BCCs allows the treatment of a large number of lesions in a single session, and is indicated when surgical treatment is not feasible for all lesions. Photodynamic therapy with 5-amino-levulinic acid may be a valid therapeutic option for flat lesions only. Intralesional application of interferon alfa-2b removes papular lesions of small size.

Aged↗
PubMed2000

Kinetic study of the indomethacin synthesis and thermal decomposition reactions.

The kinetics of indomethacin synthesis (achieved through a new method) was studied at 80 degrees C. The reaction proceeds in four steps. In the first step, by the condensation of levulinic acid with p-chlorobenzoyl-p-methoxy-phenyl-hydrazine in homogeneous acidic catalysis an intermediate is formed. In the second step, by the isomerisation of this intermediate a hydrazo compound is formed. In the third step, the isomerisation is followed by the o-benzydinic transposition of the reaction product mentioned above. In the fourth step, indomethacin is formed through a cyclization reaction. The rate constant of the indomethacin synthesis reaction was determined assuming that the cyclization reaction constitutes the rate-determining step. Spectrophotometric methods were used both in order to investigate the kinetics of the synthesis reaction and to verify the proposed mechanism. Then, a thermogravimetric study was performed on the purpose of finding out the temperature range in which indomethacin is stable. From the thermogravimetric curve kinetic parameters have been derived, using different calculation techniques.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Lanthanum(III)-catalyzed degradation of cellulose at 250 degrees C.

Lanthanum(III) chloride was found to effectively catalyze the degradation of cellulose in water at 250 degrees C. The degradation conversion of cellulose in the presence of a catalytic amount of lanthanum chloride reached 80.3% after 180 s, which corresponded to the turnover number of 83, whereas the reaction did scarcely proceed in the absence of the catalyst. The degradation products were separately quantified as water-soluble (WS), methanol-soluble (MS), methanol-insoluble (MI), and gaseous (G) products. The HPLC and GC analyses revealed that the WS materials are mainly composed of 5-hydroxymethyl-2-furaldehyde (HMF), D-glucose, and levulinic acid. Cellobiose, the disaccharide component of cellulose, was scarcely detected during the reaction.

Catalysis↗
PubMed2002

Effect of helium/neon laser irradiation on nerve growth factor synthesis and secretion in skeletal muscle cultures.

Low energy laser irradiation therapy in medicine is widespread but the mechanisms are not fully understood. The aim of the present study was to elucidate the mechanism by which the light might induce therapeutic effects. Skeletal muscle cultures were chosen as a target for light irradiation and nerve growth factor (NGF) was the biochemical marker for analysis. It was found that there is a transient elevation of intracellular calcium in the myotubes immediately after irradiation (P<0.001). Preincubation of the myotubes with either the photosensitizers 5-amino-levulinic acid (5-ALA), or with hematoporphyrin (Hp) enhanced the elevation of cytosolic calcium (P<0.001) after helium/neon irradiation (633 nm) with an energy of 3 J/cm(2). In addition, helium/neon irradiation augmented the level of NGF mRNA fivefold and increased NGF release to the medium of the myotubes. Thus, it is speculated that transient changes in calcium caused by light can modulate NGF release from the myotubes and also affect the nerves innervating the muscle. The NGF is probably responsible for the beneficial effects of low-level light.

Animals↗
PubMed2004

Use of a Design of Experiments approach for the optimisation of a microwave assisted Ugi reaction.

The utility of a Design of Experiments (DoE) approach for the rapid and efficient optimisation of a microwave assisted Ugi 3cc reaction of levulinic acid is demonstrated. DoE methods have also been applied to the assessment of the reaction scope for a range of amine and isonitrile substrates. The optimal procedure developed using this approach has enabled the preparation of lactam derivatives in moderate to excellent yields (17-90%) in a reaction time of only 30 min compared to the conventional methodology which required up to 48 h.

Journal Article↗
PubMed2006

Incorporation of deuterium-labelled analogs of isopentenyl diphosphate for the elucidation of the stereochemistry of rubber biosynthesis.

A series of six deuterium-labelled analogs of isopententyl diphosphate (IPP) was prepared to investigate the detailed stereochemical course of addition of C5 units during rubber biosynthesis in Hevea brasiliensis and Parthenium argentatum. These analogs were incorporated into the cis-polyisoprene chain by rubber transferase in rubber particles, and the stereochemistry was determined by 2H-NMR analysis of the polymer or of levulinic acid derivatives obtained from its ozonolytic degradation. Results indicate that rubber chain elongation occurs with loss of the pro-S hydrogen of IPP, addition of the allylic diphosphate to the si face of IPP and inversion of stereochemistry at the carbon bearing the diphosphate.

Alkenes↗
PubMed1976

Identification of cysteine as the reactive group in pyruvate kinase alkylated by 5-chloro-4-oxopentanoic acid.

4-Hydroxypentanoic acid alanine thioether was synthesized and characterized by n.m.r. spectroscopy. This derivative corresponded to the modified amino acid obtained by allowing 5-chloro-4-oxo[3,5-3H]pentanoic acid to react with rabbit muscle pyruvate kinase. Performic acid oxidation of 4-oxo[3,5-3H]pentanoic acid alanine thioether in pyruvate kinase gave [3H]succinate (67%) and [3H]carboxymethylcysteine (33%) as expected. Evidence is presented to show that NaBH4 reduction followed by periodate oxidation and analysis of radioactive formaldehyde production may provide a convenient method for distinguishing between thiol and amino alkylation by halogenomethyl ketone compounds. Peptide 'mapping' confirms that the modification by 5-chloro-4-oxopentanoic acid occurs primarily at one region of pyruvate kinase.

Alkylation↗
PubMed1995

A cellular stress model for the sequestration of redox-active glial iron in the aging and degenerating nervous system.

The mechanisms responsible for the accumulation of redox-active brain iron in normal senescence and in Parkinson's disease remain poorly understood. The aminothiol compound cysteamine (CSH) induces the appearance of autofluorescent, iron-rich cytoplasmic granules in cultured astroglia that are identical to glial inclusions that progressively accumulate in the aging periventricular brain. Both in situ and in culture, these glial inclusions appear to arise in the context of a generalized cellular stress (heat shock) response. Several laboratories have previously concluded that porphyrins and heme ferrous iron are responsible, respectively, for redorange autofluorescence and nonenzymatic peroxidase activity in the glial inclusions. In the present study we found that, contrary to hypothesis, CSH suppresses the incorporation of the heme precursors delta-amino[14C]-levulinic acid and [14C]glycine into astroglial porphyrin and heme in primary culture. Similar results were obtained when the cells were preloaded with radiolabeled heme precursors for 24 h before CSH treatment, suggesting that the latter directly inhibits porphyrin-heme biosynthesis rather than limiting precursor uptake by these cells. We also demonstrated that CSH exposure results in the sequestration of iron-59 by astroglial mitochondria (granule precursors). The results of this study suggest that stress-related trapping of nonheme iron by astroglial mitochondria may be an important mechanism underlying the pathological accumulation of redox-active iron in the basal ganglia of subjects with Parkinson's disease. CSH-treated astrocytes provide a useful model to investigate the role of stress-related dysregulation of neuroglial iron metabolism in the aging and degenerating nervous system.

Aging↗