bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the antiproliferative cyclopentenone prostaglandin A1 on glutathione metabolism in human cancer cells in culture
Authors: de Bittencourt Paulo Homem , Miyasaka Célio K. , Curi Rui , Williams John F. 
Published: July 2007

AbstractHomeostatic mechanisms for the maintenance of glutathione (GSH) are fundamental in the provision of a cellular defense against electrophilic/oxidant challenges. Cyclopentenone prostaglandins (CP‐PGs) are powerful antiproliferative endogenous substances that may act as electrophilic regulating compounds, by virtue of the presence of an α,β‐unsaturated carbonyl group in the cyclopentane ring. Nevertheless, differential resistance to CP‐PG cytotoxic/cytostatic effect has been reported in different cell types. It is reported that the activity/expression of γ‐glutamylcysteine synthetase (γ‐GCS, the rate‐limiting enzyme in GSH biosynthesis) can be inducibly activated by electrophiles, including CP‐PGs. The response of the human cancer strains HEp‐2 (larynx carcinoma) and HL‐60 (promyelocytic leukemia) cells to treatment with the CP‐PG PGA1 in culture was investigated by evaluating the time‐course of GSH synthesis and activity of enzymes of GSH metabolism, other than γ‐GCS, after PGA1 addition. HEp‐2 cells, being more resistant to PGA1 cytotoxic and cytostatic effects, have basal GSH levels that were 2.4‐fold higher than that of HL‐60 cells. The activities of GSH S‐transferase (GST), glutathione reductase (GSRd) and glutathione peroxidase (GSPx) are constitutively higher in HL‐60 cells than in HEp‐2 cells (respectively, 17.0‐, 28.5‐ and 12.3‐fold). When challenged with PGA1, both cell types exhibited a dose‐dependent rise in GSH content that was maximal 18 h after PGA1 addition and was preceded by a rise in GST and GSRd activities in both cell types (at 12 h). GSPx activity increased only in HEp‐2 (PGA1 evoked a 93.4%‐inhibition in HL‐60 cells). Moreover only HEp‐2 cells exhibited early capacity to enhance GSH content (1‐2 h just after PGA1 addition). These results and earlier data showing that leukemia cells are sensitive to CP‐PG treatment suggest that deficiencies in GSH metabolism may be strategic in therapeutic approaches to the treatment of human leukemias.
Thiamine triphosphatase activity in bovine kidney
Authors: Makarchikov Alexander F. , Chernikevich Ivan P. 
Published: July 2007

AbstractProperties of soluble thiamine triphosphatase (ThTPase), adenosine triphosphatase, nucleoside triphosphatase and alkaline phosphatase activities in bovine kidney were compared. ThTPase and the other phosphatases differed clearly in their pH‐dependences, Km and molecular masses. Apparent Km and pH optimum for ThTPase were determined to be 45.5 μM and 8.9, respectively. Molecular mass of the enzyme was 29.1 kDa as estimated by Sephadex G‐100 gel filtration. The results obtained show bovine kidney to contain a specific soluble ThTPase, this enzyme being the only one hydrolyzing low concentrations of ThTP.
Enhancement of hydroxyl radical generation in the fenton reaction by alpha‐hydroxy acid
Authors: Ali M. Aktar , Konishi Tetsuya 
Published: July 2007

AbstractThe effect of various organic acids on hydroxyl radical (· OH) generation in the Fenton reaction were examined by the ESR spin trapping technique, where 5,5‐dimethyl‐1‐pyroline‐N‐nitroxide (DMPO) and α‐phenyl‐tert‐ butyl nitrone (PBN) were used as the spin trapping reagents. α‐Hydroxy acids such as lactic acid, glycolic acid and 2‐hydroxy isobutyric acid were found to markedly enhance · OH generation in the reaction. In contrast, β‐hydroxy acid, α‐keto acid, esters of α‐hydroxy acids, aldehydes and other straight chain organic acids had no such enhancing activity, α‐Amino acids had also no enhancing effect. The results suggest that the α‐hydroxy acid moiety is prerequisite for the enhancement of · OH generation in the Fenton reaction. Superoxide dismutase did not inhibit the enhancing effect of α‐hydroxy acids whereas catalase completely inhibited the · OH generation. Thus, α‐hydroxy acids directly enhanced the · OH generation via the Fenton reaction but not the Haber‐Weiss reaction. Possible role of lactic acid manipulating · OH generation is discussed in relation to the ischemia‐reperfusion cell damage.
Sulphydryl groups and their relation to the antioxidant enzymes of chelonian red blood cells
Authors: Torsoni M. A. , Viana R. I. , Ogo S. H. 
Published: July 2007

AbstractThiol groups of hemoglobin and blood glutathione are higher in Geochelone carbonaria than in Geochelone denticulata. Exposure of stripped hemolysate of both tortoises to terc‐butyl hydroperoxide, resulted in a higher ferroheme oxidation of G. denticulata hemoglobin. In this example glutathione reductase and glutathione peroxidase, were not active due to the absence of GSH and NADPH, suggesting that the thiol groups of G. carbonaria hemoglobin act as antioxidant, similar to GSH. In the total hemolysate, however, where the antioxidant enzymes are active, both species showed similar levels of hemoglobin oxidation, suggesting that the protective effect of thiol groups of hemoglobin are less effective for heme protection. The activity of glutathione reductase and glutathione peroxidase was higher in erythrocytes of G. denticulata and the activity of catalase and superoxide dismutase was higher in erythrocytes of G. carbonaria.
Seroconversion of type B to O erythrocytes using recombinant Glycine max α‐D‐galactosidase
Authors: Vosnidou Nancy C. , Johnson Scott A. , Mitra Moon Moon , Wells Donald C. , Li Chun Qin , Evans Maria L. , Harmata Michael A. , Walker John C. , Smith Daniel S. 
Published: July 2007

AbstractRecombinant α‐D‐galactosidase (rGal) from soybean (Glycine max) hydrolyzed the immunodominant α‐D‐galactose residue from the B epitope of red blood cells. This converted type B erythrocytes to type O which are “universally” transfusable. Type B red blood cells were obtained from four different donors and enzymatically converted. Cell function parameters, including red cell indices, pH, methemoglobin, carboxyhemoglobin, osmotic fragility, hemolysis, 2,3‐diphosphoglycerate, cholinesterase, ATP, and antigen typing of treated ceils were compared to controls. These pilot studies indicate that rGal could have potential biotechnical application in the production of universally transfusable red blood cells.
Kinetics of inhibition of penaeus penicillatus acid phosphatase by bromoacetic acid
Authors: Chen Qing‐Xi , Chen Su‐Li , Zhou Hai‐Meng 
Published: July 2007

AbstractThe kinetics of inhibition of penaeus penicillatus acid phosphatase by bromoacetic acid has been studied. The results show that inhibition of the enzyme by bromoacetic acid is a slow, reversible reaction. The microscopic rate constants for the reaction of inhibitor with the enzyme were determined. The presence of the substrate offers marked protection of this enzyme against inhibition by bromoacetic acid. The above results suggest that the histidine residue is essential for activity and are situated at the active site of the enzyme.
The role of counterions in the protective action of some antioxidants in the process of red cell oxidation
Authors: Kleszczynska Halina , Sarapuk Janusz 
Published: July 2007

AbstractA number of new surfactants with an incorporated antioxidant functional group were synthesized in order to be used as agents protecting biological and/or model membranes against lipid peroxidation. Hydrophobic parts of these amphiphilic antioxidants ensured their incorporation into the membranes studied, viz. pig erythrocytes. Proper concentrations of the antioxidants were used to avoid erythrocyte membrane destruction during the experiments. The work contains the results of studies on the protective effect of two groups of antioxidants. They differed in the chain length incorporated into the membrane hydrophobic part and in the kind of counterion (chloride and bromide). The role of these factors in the protective action of the compounds studied is discussed as well as their practical application.
Purification, separation and characterization of phosphoglucomutase and phosphomannomutase from maize leaves
Authors: Popova T. N. , Matasova L. V. , Lapotko A. A. 
Published: July 2007

AbstractDifferent phosphomutases‐phosphogluconmtase (EC 2.7.5.1; PGM) and phosphomannomutase (EC 2.7.5.7; PMM) from maize (Zea mays L.) leaves have been purified. PGM and PMM were completely separated from each other. The purified PGM was shown to be electrophoretically homogeneous. The PGM fiom maize leaves was found to be a homodimer with an apparent molecular mass of 132 kDa, the size of the subunits was 66 kDa. The PGM is a bifunctional enzyme, which can use both glucose‐1‐ phosphate and mannose‐1‐phosphate as substrates. In contrast, the PMM appears to be monospecific for mannose‐1‐phosphate. Evidence is presented that PMM differs from PGM. Some properties of the maize leaves PGM and PMM differ in many respects (Km for substrates, pH optimum). However, some properties of PGM and PMM were similar (influence of Mg2+ and Mn2+ ions).
Simple determination of peroxyl radical‐trapping capacity
Authors: Bartosz Grzegorz , Janaszewska Anna , Ertel Danuta , Bartosz Maŀgorzata 
Published: July 2007

AbstractA simple spectrophotometric method of determination of peroxyl radical‐trapping capacity (PRTC) of body fluids and food products is proposed. In this method, decomposition of 2,2′‐azobis(2‐amidopropane) hydrochloride (ABAP) is the source of peroxyl and alkoxyl radicals which oxidize 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) to a green cation radical. Antioxidant present in a sample inhibit the reaction; the induction time of the reaction is proposed as a parameter enabling determination of antioxidant content. Standard assay conditions are: 20 mM ABAP and 150 μM ABTS in 0.1 M phosphate buffer, pH 7.0, at 37°C; absorbance is monitored at 414 nm. A 10‐min assay allows for determination of the induction time of appropriately diluted sample. As examples of application of this method, PRTC values of several types of beverages are reported.
Modelling cortical cataractogenesis XX. In vitro effect of α‐lipoic acid on glutathione concentrations in lens in model diabetic cataractogenesis
Authors: Kilic Fusun , Handelman Garry J. , Traber Katrina , Tsang Kenny , Packer Lester , Trevithick John R. 
Published: July 2007

AbstractIn previous studies stereospecific protection against lens opacity was consistent with specific reduction of R‐α‐lipoic acid(R‐α‐LA) in mitochondria of the vulnerable cells at the lens equator where the first globular degeneration is seen in glucose cataract. In this study two further possible explanations of this effect were investigated: (1) increased glucose uptake by the lens, leading to increased glycolysis and release of lactate into the incubation medium and/or (2) maintenance of glutathione levels by the R‐α‐LA. The data did not support 1, but was consistent with 2, after 24 hr incubation. The concentrations of glutathione in normal lenses or lenses incubated with R‐ or racemic α‐LA were not significantly different, but the concentration of glutathione in lenses incubated with S‐α‐LA was significantly lower than the R‐α‐LA‐incubated lenses.
Endothelin 1 action on isolated rat stomach and the role of calcium ions in ET 1 induced depolarization of smooth muscle cells BC3H1
Authors: Hukovic N. , Hadziselimovic R. 
Published: July 2007

AbstractEndothelins; (ET1, ET2 and ET3) are a family of peptides which acts on different smooth muscle preparations inducing a slow long lasting contraction. We investigated the effects of ET 1 modulatory action on adrenergic, cholinergic and serotoninergic transmission on an isolated mouse's stomach with gastric nerves. The endothetin 1 stimulation of the mouse stomach tone was abolished by the specific serotonin antagonist methizergid. This study suggests that endothelin 1 plays a role in the regulation of nonvascular smooth muscle tone. The endothelin effect was dependent on free intracellular Ca++ which can be recruited from an extracellular solution as well as from intracellular stores. Complete reduction of Ca++ from the extracellular solution with a simultaneous depletion of calcium stores abolished endothelin 1 depolarization of BC3H1 cells.
Age‐related changes in plasma and tissue fatty acid composition in Fischer 344 rats
Authors: Engler Marguerite M. , Engler Mary B. , Nguyen Huong 
Published: July 2007

AbstractAdvancing age is associated with increased risk of coronary artery disease. Changes in fatty acid metabolism affect important cellular membrane properties and functions which may contribute to the vascular pathophysiology of aging. This study was designed to investigate the effects of aging on the fatty acid composition of the plasma, liver, aorta, and renal artery in 4‐, 15‐, and 24‐month old Fischer 344 rats, an animal model for aging. With aging, the levels of total polyunsaturated fatty acids (PUFA) increased in the plasma, aorta, and renal artery. The major changes in the liver fatty acid profile were increases in the levels of 18:2n6 and 18:3n3 and a decrease in the levels of 20:3n6 and 20:5n3. The results indicate that significant shifts occur in the levels of n6 and n3 PUFA in the plasma, liver, and vasculature with aging. The alterations in the fatty acid composition may be a pathogenetic mechanism of the vascular changes associated with aging.
Preferential accumulation of muscle type acylphosphatase in the nucleus during differentiation
Authors: Raugei G. , Degl'Innocenti D. , Chiarugi P. , Solito E. , Modesti A. , Ramponi G. 
Published: July 2007

AbstractIn a previous paper we observed a direct involvement of acylphosphatase in differentiation, associated with enhanced levels of the enzyme in the cell. We have here investigated the subcellular localization of the two known acylphosphatase isoforms during this proces. We show that in C2C12 myoblast cells, muscle type acylphosphatase accumulates in the nucleus during differentiation. The same pattern of accumulation is observed also in K562 erythroleukemia cells, although at a lower extent: this fact indicates that this phenomenon is not restricted to muscular cells but rather it could be of general importance in the differentiative process. The common type acylphosphatase, showing an 8‐fold increase in the cytoplasm during differentiation, does not accumulate in the nucleus, suggesting distinct roles of the two isoenzymes in this process.
Different effects of the constituents of EGb761 on apoptosis in rat cerebellar granule cells induced by hydroxyl radicals
Authors: Chen Chang , Wei Taotao , Gao Zhonghong , Zhao Baolu , Hou Jingwu , Xu Huibi , Xin Wenjuan , Packer Lester 
Published: July 2007

AbstractThe present study was conducted to evaluate the different effects of the constituents of EGb761(Ginkgo biloba Extract) on apoptosis in cerebellar granule cells induced by hydroxyl radicals. The total flavonoid component of EGb761, two pure EGb761 components (rutin and quercetin), and a mixture of flavonoids and terpenes protected cerebellar granule cells from oxidative damage and apoptosis induced by hydroxyl radicals. ESR(electron spin resonance) results showed that the IC50 of the flavonoids for scavenging hydroxyl radicals was almost the same as that of EGb761, even though flavonoids make up only 24% of EGb761, implying that other constituents of EGb761 besides flavonoids can scavenge hydroxyl radicals. Total terpenes of EGb761 did not protect against apoptosis. Flavonoids and terpenes did not show a synergistic effect in this regard. Terpenes did not scavenge hydroxyl radicals directly, which might be related to their “cage‐like” structures.
Arachidonoyl‐CoA: Lysophosphatidylcholine acyltransferase activity in ras‐transformed NIH 3T3 fibroblasts depends on the membrane composition
Authors: Momchilova Albena , Markovska Tania , Pankov Roumen 
Published: July 2007

AbstractInvestigations were performed on the influence of membrane lipids on arachidonoyl‐CoA: lysophosphatidylcholine acyltransferase in microsomal membranes from control and ras‐transformed NIH 3T3 fibroblasts. Of all the tested phospholipids only sphingomyelin induced activation of acyltransferase in membranes from ras‐transformed cells. No specific phospholipid effect on the acyltransferase was observed in microsomal membranes from control fibroblasts. Diacylglycerol was found to inhibit acyltransferase in both cell lines, whereas ceramide accumulation induced inhibition only in membranes from the transformed cells. The effects of diacylglycerol, ceramide, sphingomyelin and sphingomyelinase are discussed with respect to their putative roles in the signal transduction pathways in oncogene‐expressing cells.
Lipid peroxidation induced by the Cu,Zn‐superoxide dismutase and hydrogen peroxide system
Authors: Kwon Oh Bin , Kang Jung Hoon 
Published: July 2007

AbstractCu,Zn‐superoxide dismutase (SOD) can catalyze hydroxyl radical generation using H2O2 as a substrate. Lipid peroxidation induced by the Cu,Zn‐SOD and H2O2 system was investigated. When linoleic acids micelles or phosphatidylcholine liposomes were incubated with Cu,Zn‐SOD and H2O2, lipid peroxidation was gradually increased in a time‐dependent manner. The extent of lipid peroxidation was proportional to Cu,Zn‐SOD and H2O2 concentrations. Hydroxyl radical scavengers and copper chelator inhibited lipid peroxidation induced by the Cu,Zn‐SOD and H2O2 system. These results suggest that lipid peroxidation is mediated by the Cu,Zn‐SOD and H2O2 system via the generation of hydroxyl radicals by a combination of the peroxidative reaction of Cu,Zn‐SOD and the Fenton‐like reaction of free copper released from oxidatively damaged SOD.
Cloning, sequencing, expression and characterization of the manganese superoxide dismutase gene from Vibrio alginolyticus
Authors: Shyu Yu‐Chiau , Chiu Chi‐Chien , Lin Fu‐Pang 
Published: July 2007

AbstractThe sodA gene coding for manganese superoxide dismutase from the marine microorganism Vibrio alginolyticus was cloned, sequenced and over‐expressed in Escherichia coli using the pET20b (+) expression vector. The full‐length gene was consisted of 603bp open reading frame, which encoded a polypeptide of 201 amino acid residues, with a calculated molecular weight of 22672Da. The deduced amino acid sequence of the sodA showed considerable homology to other Mn‐SODs. The recombinant enzyme was efficiently purified from crude E. coli cell lysate by the metal ion affinity chromatography. The recombinant VAMn‐SOD resisted thermo‐denaturation up to 60°C and was insensitive to inhibitors such as H2O2, NaN3 and diethyldithiocarbamic acid.
Can serum amyloid a or macrophage colony stimulating factor serve as marker of amyloid formation process?
Authors: Rysavá R. , Merta M. , Tesar V. , Jirsa M. , Zima T. 
Published: July 2007

AbstractAmyloid formation depends on amyloid precursor production and is influenced by the activity of the underlying disorder and mediated by some proinflammatory cytokines. In this pilot study we tried to find some specific markers that could establish the activity of the disease. We investigated 45 samples of sera and 38 samples of urine from patients (pts) with secondary amyloidosis (AA), primary amyloidosis (AL), systemic autoimmune diseases with renal impairment (Vase) and healthy controls (Co). Pts with AA had increased plasma levels of TNFα (9.97±4.22 vs. 2.63±1.34 pg/mL, p<0.001) and SAA (43.14±16.0 vs. 3.42±0.7 ng/mL, p<0.05) in comparison with Co. Plasma levels of M‐CSF in the AA group were significantly increased in comparison with Co (1077.34±238.6 vs. 137.71±19.6, pg/mL, p<0.001) and also in comparison with Vase (482.24±86.7 pg/mL, p<0.05). Urinary excretions of TNFα (8.92±8.1 vs. 0.17±0.11 μg/mol creatinine, p<0.01), slL‐6R (1.39±1.14 vs. 0.07±0.05 g/mol creatinine, p<0.01) and M‐CSF (650.2±153.7 vs. 33.3±8.6 t.tg/mol creatinine, p<0.01) in AA were significantly increased in comparison with Co. Pts with AL had increased plasma levels of M‐CSF (819.83±264.2 vs. 137.71±19.6 pg/mL, p<0.05) and urinary excretion of M‐CSF (865.0±188.4 vs. 33.3±8.6μtg/mol creatinine, p<0.01) in comparison with Co. SAA has a low specificity for amyloidosis but is a sensitive acute phase reactant. TNFα, a proinflammatory cytokine, may reflect the activity of the underlying diseases in secondary amyloidosis. M‐CSF was increased both in plasma and urine in amyloidosis groups and seems to be the most promising (possibly specific) marker of amyloidosis.
Speaking Out of Turn: A Role for Silent Synapses in Pain
Authors: Kerchner Geoffrey A. , Li Ping , Zhuo Min 
Published: July 2007

AbstractSevere tissue or nerve injury can result in a chronic and inappropriate sensation of pain, mediated in part by the sensitization of spinal dorsal horn neurons to input from primary afferent fibers. Synaptic transmission at primary afferent synapses is mainly glutamatergic. Although a functioning excitatory synapse contains both alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazoleproprionic acid (AMPA) and N‐methyl‐D‐aspartate (NMDA) receptors in the postsynaptic membrane, recent evidence suggests that dorsal horn neurons contain some “silent” synapses, which exhibit purely NMDA receptor‐mediated evoked postsynaptic currents and do not conduct signals at resting membrane potential. Serotonin, which is released onto dorsal horn neurons by descending fibers from the rostroventral medulla, potentiates sensory transmission by activating silent synapses on those neurons, i.e., by recruiting functional AMPA receptors to the postsynaptic membrane. This phenomenon may contribute to the hyperexcitability of dorsal horn neurons seen in chronic pain conditions.
Accelerated random search method for dynamic FE model updating
Authors: Touat N. , Pyrz M. , Rechak S. 
Published: July 2007

PurposeThis paper seeks to present a new solution algorithm for updating of finite element models in structural dynamics. A random search method is applied to improving the correlation between the numerical simulation and the measured experimental data.Design/methodology/approachDynamic finite element model updating may be considered as an optimization process. It is solved using modified accelerated random search (MARS) algorithm. The effectiveness of the approach is first tested on benchmark problems. Next, several objective function formulations for dynamic model updating in modal and frequency domains are investigated for numerically simulated vibrating beam. Finally, the algorithm is applied to a real beam‐like structure using measured modal data.FindingsThe MARS algorithm is able to provide very good results in a reduced time even for hard optimization problems. It behaves very well also for the FE dynamic model updating, highly coupled problems. The efficient updating criterion has been proposed and the approach has been validated experimentally.Research limitations/implicationsThe method is supposed to be time consuming for large size or complicated objective function problems but the choice of optimization parameters can accelerate the convergence.Practical implicationsThe MARS algorithm can be applied to model updating in civil and mechanical engineering.Originality/valueThis paper is the first to apply the MARS algorithm to the problem of FE model updating in dynamics and enables one to obtain very good results. Efficient criteria for model updating have been proposed.