bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification of α‐mannosidase activity from Indian lablab beans
Authors: Tulasi Rajasekhar Baru , Nadimpalli Siva Kumar 
Published: July 2007

AbstractSeeds of Dolichos lablab var. typicus (Indian lablab beans contain a glucose/mannose specific lectin that was affinity purified on Sepharose mannose columns in our laboratory. The unbound fraction from this matrix showed α‐mannosidase activity. In the present study this has been purified to homogeneity by a combination of ion‐exchange, hydrophobic chromatography and gel filtration. Purified α‐mannosidase had an apparent molecular weightof 195,000±5,000 with 4.5% carbohydrate. On SDS‐PAGE under reducing conditions, the enzyme dissociated into two major bands corresponding to Mr 66,000 and Mr 44,000. An antibody to the well studied jack bean α‐mannosidase cross‐reacts with the enzyme from the lablab beans suggesting antigenic similarity between these two legume mannosidases.
Dicarbanonaborates in yeast respiration and membrane transport
Authors: Kotyk Arnošt , Lapathitis Georgios 
Published: July 2007

AbstractTwo derivatives of carborates, sodium 5,6‐dichloro‐7,8‐dicarbanonaborate (CB‐Cl) and sodium 5‐mercapto‐7,8‐dicarbanonaborate (CB‐SH) were found to inhibit endogenous as well as glucose‐induced respiration of the yeast Saccharomyces cerevisiae. Both substances slightly increased endogenous acid production, were neutral toward H+‐ATPase‐associated acidification but pronouncedly inhibited the K+‐stimulated acidification. The same effects were observed also with an ATPase‐deficient mutant of the yeast. The ATP‐hydrotyzing activity of yeast plasma membranes in vitro was severely reduced. The membrane potential was substantially increased toward more negative values. The H+‐symporting uptake of glutamic acid was considerably decreased, that of adenine was diminished much less. The effects of the dicarbanonaborates are obviously pleiotropic but their inhibition of ATP hydrolysis and of uptake of H+‐symported substances, on the one hand, and absolute lack of effect on ATPase‐catalyzed acidification, on the other, pose an unresolved problem.
Toxicity of daunorubicin and naphthoquinones to HL‐60 cells: an involvement of oxidative stress
Authors: Dičkancaité Eglé , Čénas Narimantas , Kalvelyté Audroné , Serapiniené Nijolé 
Published: July 2007

AbstractIncubation of HL‐60 cells with anthracycline daunorubicin caused an appearance of viable apoptotic, nonviable apoptotic, necrotic (nonviable nonapoptotic) and chromatin‐free (late apoptotic) cells. Both necrotic and apoptotic cell responses were partly prevented by antioxidant N,N′‐diphenyl‐p‐phenylene diamine (DPPD) and iron‐chelating agent, desferrioxamine, suggesting an involvement of activated oxygen species. The comparison of cytotoxicity of daunorubicin and of 5‐hydroxy‐ and 5,8‐dihydroxy‐1,4‐naphthoquinones revealed that at equitoxic concentrations, hydroxynaphthoquinones induced a larger number of necrotic cells in comparison to daunorubicin, a process being partly prevented by DPPD and desferrioxamine. However, we have found that cytotoxicity of daunorubicin was markedly higher in comparison with a series of naphtho‐ and benzoquinones, where an increase of cytotoxicity upon increase in single‐electron reduction potential of quinones (E17) was observed, pointing out to redox cycling as to the main factor of cytotoxicity. This discrepancy could be explained by additional factor(s) of daunorubicin cytotoxicity, e.g. DNA‐intercalation, or selective accumulation of daunorubicin in cell nucleus.
Isolation of a gene encoding nodulin‐like intrinsic protein of Escherichia coli
Authors: Fushimi Kiyohide , Bai Liqun , Marumo Fumiaki , Sasaki Sei 
Published: July 2007

AbstractMembers of the membrane intrinsic protein (MIP) family are expressed in various organisms including plants, insects, and vertebrates. E. coli is known to have a MIP member gene, glycerol facilitator (GlpF). Here we report the isolation of E. coli gene encoding BniP, bacterial nodulin‐like intrinsic protein. BniP encodes a 231 amino acid, 24 kDa protein with 42 % amino acid identity to Nod26, 38 % amino acid identity to AQP1, and 29 % amino acid identity to GlpF. Analysis of deduced amino acid sequence predicted a hydrophobic protein with six membrane‐spanning domains. Expression of BniP in Xenopus oocytes induced slight increase in osmotic water permeability, but not glycerol or ion permeability. Our results showed that BniP is a new member of the MIP channel‐forming proteins of E. coli.
Mutagenic and genotoxic activities of four pesticides: Captan, foltaf, phosphamidon and furadan
Authors: Saxena Sangeeta , Ashok B. T. , Musarrat Javed 
Published: July 2007

AbstractThe mutagenic and genotoxic potential of four pesticides viz. captan, foltaf, phosphamidon and furadan was evaluated by the Ames mutagenicity assay and their DNA damaging ability on radiation repair defective E. coli K‐12 strains respectively. The mutagenic spectrum revealed captan to be most mutagenic in the absence of metabolic activation, while the presence of S9 mix led to an attenuated mutagenic response. Foltaf, phosphamidon and furadan were detected as relatively weaker mutagens. A significant decrease in the survival of SOS defective mutants, recA, lexA and pol‐ of E. coli was observed as compared to their wild‐type counterparts in the presence of the pesticides. The role of SOS repair genes gains further support from the Salmonella strains triggering the error‐prone SOS response.
Mouse deoxyribonuclease I (DNase I): Biochemical and immunological characterization, cDNA structure and tissue distribution
Authors: Takeshita Haruo , Yasuda Toshihiro , Nakajima Tamiko , Hosomi Osamu , Nakashima Yoshimitsu , Kishi Koichiro 
Published: July 2007

AbstractMouse urinary deoxyribonuclease I (DNase I) resembles rat and human DNase Is in terms of its proteochemical and enzymological properties. Furthermore, mouse DNase I was demonstrated to be immunologically closer to the rat than to the human enzyme. A 1176 bp full length cDNA encoding mouse DNase I was constructed from RNA obtained from the kidney and parotid glands. The amino acid sequence up to the 45th residue from the N‐terminal of the mature enzyme was identical to that deduced from the cDNA sequence. This DNase I was distributed most densely in the parotid glands from the standpoint of both enzyme activity and gene transcript levels.
Effect of free fatty acids on erythrocyte morphology and membrane fluidity
Authors: Zavodnik Ilya B. , Zaborowski Andrzej , Niekurzak Andrzej , Bryszewska Maria 
Published: July 2007

AbstractChanges in red blood cell shape and membrane properties in response to the interaction with free fatty acids and their derivatives were studied by light scattering at small and large angles, light microscopy and fluorescence anisotropy. The influence of these agents depended on the end groups and increased with increasing chain length. The fatty acids exerted a biphasic effect on the cell size, shape and surface properties, and induced erythrocyte aggregation. After transient size alteration with a reduction in diameter, caused by low free fatty acid concentrations (up to 5‐10 μM in the case of palmitic acid), fatty acids increased the erythrocyte diameter at higher concentrations (20‐60 μM in the case of palmitic acid). The aliphatic aldehydes and methyl esters of fatty acids significantly decreased the cell diameter at the concentrations used. Changes in erythrocyte shape and size were accompanied by changes in membrane microviscosity. Palmitic acid decreased the rotational diffusion of the fluorescence probe incorporated into the membrane whereas methyl ester of palmitic acid and laurie aldehyde increased probe mobility. Also the erythrocyte modification by malondialdehyde influenced cell morphology and highly decreased membrane fluidity.
Relation of biological activity of mutant forms of recombinant human tumor necrosis factor alpha and accumulation of sphingosine in murine liver
Authors: Alessenko A. V. , Korobko V. G. , Khrenov A. V. , Rozhnova U. A. , Soloviev A. S. , Shingarova L. N. 
Published: July 2007

AbstractTNF‐α induced sphingomyelin hydrolysis by sphingomyelinase and both sphingosine and ceramidc generation have been reported to be implicated in a number of TNF‐α responses, including cytotoxicity and apoptosis. We found that sphingosine, a highly cytotoxic product of enzymatic degradation of sphingomyelin, is accumulated in liver of mice treated with TNF‐α. To determine the role of sphingosine in TNF‐α toxicity, TNF‐α mutants differing in their cytotoxicity to L929 cells as well as haemorrhagic tumor necrosis, tumor regression and lethal toxicity in mice were used in our experiments. The mutants with highest toxicity and tumor‐necrotizing activity caused accumulation of sphingosine exceeded its control level 5,5 times in murine liver cells. TNF‐α variants which caused moderate increase in sphingosine content were significantly less toxic. The observed relationship between toxicity of TNF‐α mutants, the toxicity of sphingosine, and the extent of its accumulation in murine liver provides evidence to suggest that this sphingomyelin metabolite may be mediator of TNF‐α ‐ induced cell damage and death.
Half‐life of Escherichia coli polyadenylated lipoprotein mRNA
Authors: Taljanidisz Janos , Shen Ping , Sarkar Nilima 
Published: July 2007

AbstractIn the light of recent evidence that the half‐life of bacterial mRNA may be modulated by polyadenylation at the 3′ end, we determined the half‐life of polyadenylated lpp mRNA, which is an abundant and comparatively stable message encoding a major lipoprotein of the outer membrane. Messenger RNAs were pulse‐labeled with [3H] adenosine and poly(A) RNA was isolated at various times after pulse‐labeling by affinity chromatography on oligo(dT) cellulose. The amount of lpp mRNA remaining was quantitated by hybridization with the antisense strand of the lpp gene cloned in M 13mp18. The observed half‐life for polyadenylated lpp mRNA was 12 min. This represents the first half‐life measurement for a specific polyadenylated mRNA in E. coli, and is slightly longer than the half‐life of total lpp RNA reported earlier. It coincides with the functional half‐life for lpp mRNA determined by Inouye and coworkers by measuring the rate of lipoprotein synthesis at various times after rifampicin addition. This suggests that polyadenylated lpp RNA is the predominant and translationally active form of lpp mRNA within the cell.
Use of an automated sequencer to determine the sequence specificity of DNA damage
Authors: Hardman Leigh C. , Murray Vincent 
Published: July 2007

AbstractAn automated sequencer was used to determine the sequence specificity of DNA damage caused by hedamycin in the plasmid pUC19 using a linear amplification/Taq DNA polymerase method. Previously, manual DNA sequencers have been in widespread use to investigate the sequence specificity of a DNA damaging agent. Manual DNA sequencers are restricted in the length of DNA sequence that can be read at base pair resolution for densitometry. An automated sequencer can greatly expand on the length of analysable DNA sequence. An additional important capability of the automated sequencer, is the ability to quantitate the intensity of damage at each base pair site. Thus we have used the automated sequencer to elucidate the sequence specificity of DNA damage for 300 bp. We have carried out an extended analysis of the sequence specificity of hedamycin DNA damage and found that the sequences 5′‐cGt‐3′, tGt and cGg are preferentially damaged. The sequence specificity of cisplatin was also investigated.
Nitroaromatic betulin derivatives as redox cycling agents
Authors: Miškiniene Vanda , Dičkancaite Egle , Nemeikaite Aušra , Čenas Narimantas 
Published: July 2007

AbstractWe have synthesized nitroaromatic derivatives of triterpenoid betulin (lup‐20(29)‐ene‐3β,28‐diol), betulin‐(28)‐5′‐(aziridin‐l‐yl)‐2′,4′‐dinitrobenzoate and betulin‐(28)‐5′‐nitro‐2′‐furoate. These compounds were reduced in single‐electron way by ferredoxin: NADP+ reductase and flavocytochrome b2 at rates comparable with their simple structure analogs. Besides, these compounds were substrates for DT‐diaphorase. Their toxicity to bovine leukemia virus‐transformed lamb fibroblast culture was partly prevented by antioxidant N,N′‐diphenyl‐p‐phenylene diamine and desferrioxamine, indicating an involvement of oxidative stress in their cytotoxicity.
Human placenta cytidine deaminase: a zinc metalloprotein
Authors: Vincenzetti Silvia , Cambi Alessandra , Balducci Enrico , Natalini Paolo , Volpini Rosaria , Vita Alberto 
Published: July 2007

AbstractCytidine deaminase, a tetrameric enzyme purified from human placenta, was shown to contain a single atom of tightly bound zinc per subunit by Inductively Coupled Plasma Optical Emission Spectrometry analysis. The metal appears to be involved in catalysis, as suggested by the inhibition exerted by 1,10‐phenanthroline and dipicolinic acid. This hypothesis is further supported by the finding that the presence of substrate protects the enzymatic activity from dipicolinic acid inhibition. Furthermore the total cysteine residues per subunit were investigated by sulphydryl groups titrating agents.
Interactions of aldolase and glyceraldehyde‐3‐phosphate dehydrogenase: molecular mass studies
Authors: Lal Ashish K. , Kayastha Arvind M. , Maihotra O. P. 
Published: July 2007

AbstractA gel penetration technique, that measures the dilution undergone by protein equilibration on a short tightly packed gel column, has been employed to determine the molecular masses of aldolase (160 kDa), glyceraldehyde‐3‐phosphate dehydrogenase (GPDH; 145 kDa) in the absence and presence of each other and of other proteins. The dilution factor (concentration of protein applied/concentration of protein after equilibration) was found to be inversely related to the molecular mass of the protein. In equimolar mixtures of aldolase and GPDH, 0.5‐2.5 μM each, the two enzymes exhibited a common molecular mass value of 309‐316 kDa. These enzymes did not undergo any self association or dissociation in this concentration range. Moreover, their molecular masses were unaffected by the presence of other proteins tested. When the concentration of one of these enzymes (aldolase or GPDH) was held constant and that of the other varied, the dilution factor of the former was decreased as the concentration of the latter was increased until it corresponded to a molecular mass of ca. 310 kDa at equimolar concentrations of the two enzymes. Further increase in the concentration of the variable enzyme had no effect. It has been suggested that aldolase and GPDH form a 1:1 complex of dissociation constant equal to or less than 5×10‐8 M. The complex was found to dissociate in the presence of KCl, (NH4)2SO4, ATP and NADH whereas its formation was favoured by fructose‐1,6‐bisphosphate, glyceraldehyde‐3‐phosphate, NAD+, ADP, AMP and phosphate ions.
Helicobacter pylori lipopolysaccharide inhibition of gastric somatostatin receptor: effect of sucralfate
Authors: Piotrowski J. , Slomiany A. , Slomiany B. L. 
Published: July 2007

AbstractIn this study, we investigated the inhibitory effect of Helicobacter pylori lipopolysaccharide on the binding of somatostatin to gastric epithelial cell membrane receptor, and assessed the effect of antiulcer agent, sucralfate, on this process. The assays conducted with the somatostatin receptor, purified from the solubilized epithelial cell membranes by affinity chromatography on Affi‐Gel‐ [D‐ Tryp8]SRIF‐14, revealed a dose‐dependent inhibition in receptor‐somatostatin binding by the lipopolysaccharide which reached a maximum of 94.1%. This effect of H. pylori lipopolysaccharide was countered by sucralfate that produced a 92.5% restoration in receptor‐somatostatin binding at 70 μg/ml of the drug. The findings demonstrate that sucralfate is capable of reversing the interference by H. pylori lipopolysaccharide with somatostatin‐receptor binding on gastric mucosal G‐cells.
The α2ß1 integrin binds to the CB4 peptide of the α2(I) collagen chain
Authors: Staatz William D. , Walsh John J. , Santoro Samuel A. 
Published: July 2007

AbstractThe adhesion of platelets and other cells to type I collagen is mediated by the α2ß1integrin. A binding site for the α2ß1 integrin within the α1(I) collagen chain has previously been localized to the cyanogen bromide fragment α(I)‐CB3. We noe show by use of inhibitory monoclonal antibodies against the α2ß1 integrin, that platelets also adhere to purified α2(I) collagen chains by a mechanism mediated by the α2ß1 integrin. Moreover, following isolation of cyanogen bromide fragments of the α2(I) collagen chain by HPLC, we demonstrate that α2ß1 integrin‐mediated adhesion is restricted to the CB4 fragment of the α2(1) collagen polypeptide. These findings indicate the presence of at least two spatially distinct binding sites for the α2ß1 integrin on the native type I collagen triple helix.
Staurosporine‐induced apoptosis of immortalized mouse proximal tubule cells is modulated by bcl‐2 expression level
Authors: Takeda Michio , Kobayashi Mami , Osaki Takako , Shirato Isao , Endou Hitoshi 
Published: July 2007

AbstractMouse terminal proximal tubule (S3)cells treated with staurosporine (STS) underwent morphological and biochemical changes characteristic of apoptosis. Treatment of S3 cells with STS, H‐7, PMA, herbimycin A or genistein caused DNA fragmentation. STS inhibited the activity of protein kinase C but not of cdc‐2 kinase in S3 cells. No change in cell cycle distribution was observed in S3 cells treated with STS. However, treatment of S3 cells with STS resulted in a decrease in the level of bcl‐2 mRNA expression in the cells. Overexpression of bcl‐2 inhibited the degree of STS‐induced apoptosis of S3 cells. In conclusion, STS induces apoptosis of mouse S3 cells via inhibition of various protein kinases including protein kinase C, and the apoptosis is modulated by the bcl‐2 expression level.
Cytotoxic activity of acetylcholine receptor ligands
Authors: Blishchenko E.Yu. , Mirkina I. I. , Mernenko O. A. , Yatskin O. N. , Satpaev D. K. , Strizhkov B. N. , Karelin A. A. 
Published: July 2007

AbstractAcetylcholine receptor ligands were studied for cytotoxicity in K562 human erythroid leukemia tumor cells. Cytotoxicity of carbachol, an agonist of acetylcholine receptors, atropine, an antagonist of muscarinic acetylcholine receptor, neurotoxin 11 (NT II) from Naja naja oxiana cobra venom and tubocurarine, antagonists of acetylcholine receptor of nicotinic type was exhibited in the 10‐7‐10‐5 M concentration range. Several cytolytic processes, two for carbachol and three for other ligands, corresponding to different concentrations of each ligand were detected. All acetylcholine receptor ligands induced internucleosomal DNA fragmentation.
Effect of selenium on human phospholipid hydroperoxide glutathione peroxidase expression and host cell susceptibility to lipid hydroperoxide‐mediated injury
Authors: Sun Qian , Kojima Hisanori , Komura Sadaaki , Ohishi Nobuko , Yagi Kunio 
Published: July 2007

AbstractWe recently isolated stable transfectants expressing human phospholipid hydroperoxide glutathione peroxidase (PHGPx) from the cells of guinea pig cell line 104C1 (Biochem. Biophys. Res. Commun. 219, 486‐491, 1996). Among them, one transfectant, designated 104C1/O4C, expressed high glutathione peroxidase activity toward dilinoleoyl phosphatidylcholine hydroperoxide (PCOOH); and another one, 104C1/O2D, moderate activity. In the present study, we investigated the effect of selenium on the PHGPx activity and on the lipid hydroperoxide‐mediated cell injury in the transfectants to clarify further the action of PHGPx in preventing oxidative injury of the cells. When transfectant 104C1/O2D cells were cultured in the medium added with 250 nM selenium, glutathione peroxidase activity toward PCOOH increased 8‐fold. Western blot analysis also revealed an increase in the amount of protein immunoreactive against anti‐rat PHGPx antibody in this transfectant. Lipid hydroperoxide‐mediated cell injury to the transfectant 104C1/O2D was significantly suppressed in accordance with the increase in the enzyme activity when the cells were cultured in the medium added with selenium. On the contrary, neither glutathione peroxidase activity toward PCOOH nor susceptibility to the injury was affected by selenium addition to the medium of the parental 104C1 cells, which have no selenium‐dependent glutathione peroxidase. These results clearly support our previous conclusion that expression of PHGPx is responsible for the protection of host cells from lipid hydroperoxide‐mediated injury.
Activity profile of placental superoxide‐superoxide dismutase system in pregnant mice and its possible relation with placental steroidogenesis
Authors: Laloraya Malini , Thomas Monzy , Jain Sudhir , Jafri Farzana , Pradeep Kumar G. 
Published: July 2007

AbstractPlacenta in mouse generate increasing quantities of superoxide dismutase from day 13 of pregnancy until parturition. This is associated with a concomitant reduction in the activity of superoxide radical. This findings points to the steroidogenic control of the later half of pregnancy by the placental axis. Parturition is associated with an abrupt spurt in superoxide radical. This is a novel finding and could be a consequence of the estrogen surge at labour. It is suggested that this abrupt increase in superoxide radical level at parturition may remould the placental membrane fluid at the point of its attachment with uterine membranes so as to facilitate the separation of placenta from uterus.
Endoproteases other than furin have a role in hepatic proprotein processing
Authors: Ledgerwood Elizabeth C. , Brennan Stephen O. , George Peter M. 
Published: July 2007

AbstractThe enzyme or enzymes responsible for dibasic‐directed proprotein processing in the liver have not yet been unequivocally identified, although there are a number of potential candidates. We have compared a Kex2‐like proalbumin convertase activity present in rat liver ER/Golgi membranes with recombinant furin, a candidate hepatic convertase. Using a series of mutant recombinant proalbumins as substrates the biochemically identified convertase and furin had very similar specificities with both preferring a substrate with an ArgXaaArgArg processing motif. Kinetic studies with normal and ‐4R proalbumin suggested however that the proalbumin convertase was not identical to furin. This was confirmed in immunoabsorption studies which demonstrated that furin only accounts for approximately half of the convertase activity. Therefore at least two proprotein convertases with overlapping specificities are involved in hepatic proprotein processing.
Effects of methylmalonate and propionate on [3H]glutamate binding, adenylate cyclase activity and lipid synthesis in rat cerebral cortex
Authors: de Mello C. F. , Rubin M. A. , Coelho J. , Wajner M. , Souza D. O. G. 
Published: July 2007

AbstractThe effects of methylmalonic (MMA) and propionic acid (PPA), metabolites that accumulate in methylmalonic and propionic acidemia respectively, on [3H]glutamate binding, adenylate cyclase activity and [U‐14C]acetate incorporation into lipids were investigated in rat cerebral cortex. Neither acid effected [3H]glutamate binding, regardless of the presence of sodium in the incubation medium. Also, the acids had no effect on basal or GMP‐PNP‐stimulated adenylate cyclase activity. These results suggest that MMA and PPA do not interact with glutamate binding sites and have no effect on basal or guanine nucleotide‐stimulated adenylate cyclase acitivity. In contrast, [U‐14C]acetate incorporation into brain lipids was significantly blocked by both acids, the effects being more pronounced with PPA, indicating an inhibition of brain lipid biosynthesis caused by MMA and PPA. These results may explain at least in part the hypomyelinization and/or demyelinization characteristic of patients affected by methylmalonic acidemia and propionic acidemia.