bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of interleukin‐6‐induced human immunodeficiency virus type 1 expression by anti‐GP130 monoclonal antibody
Authors: Okamoto Mika , Yasukawa Kiyoshi , Katsuura Kimio , Baba Masanori
Published: July 2007

Interleukin 6 (IL‐6) has been reported to upregulate the expression of human immuno‐deficiency virus type 1 (HIV‐1) in infected monocyte/macrophages. Since IL‐6 signal is transduced through the membrane glycoprotein gp130, we investigated the inhibitory effect of anti‐gp130 monoclonal antibody (mAb) on IL‐6‐induced viral expression in monocytic cell lines latently infected with HIV‐I. IL‐6 significantly induced the expression of HIV‐1 in U1 cells, whereas it had no effect in OM‐10.1 cells. Flow cytometric analysis revealed that U1 but not OM‐10.1 cells expressed gp130 on their surface. The anti‐gp130 mAb could inhibit IL‐6‐induced HIV‐1 expression in U1 cells in a dose dependent fashion. These results suggest that blocking the gp130 signal transduction may have therapeutic potential for the treatment of HIV‐1 infection.
Insulin rapidly stimulates ERK2 in the membrane of osteoblast‐like UMR‐106 cell
Authors: Kim Sung‐Jin , Kim Kyung‐Ha
Published: July 2007

We investigated subcellular distribution of ERK2 in osteoblast‐like UMR‐106 cell and explored to determine if its activities are regulated by insulin. 23%, 34% and 43% of total ERK2 were distributed in membrane, cytosol and nucleus, respectively. Insulin caused 40% increase of ERK2 content in membrane in 10 min whereas it induced approximately 50% decrease of ERK2 in cytosol in 10 min. In terms ofkinase activity, insulin stimulated phosphorylation of the membrane‐associated ERK2 by 2‐fold and 1.8‐fold in 1 min and 10 min and cytosolic ERK2 by 2.7‐fold and 2.3‐fold in 1 min and 10 min, respectively. In contrast, the phosphorylation of nuclear ERK2 was stimulated by insulin in time‐dependent manner with maximal (3‐fold) activity observed at 30 min. Insulin also increased the content of MEK2 in membrane by 2.2‐ to 2.6‐fold in 10 min. MEK2 translocated into mambrane in response to insulin may play a role in the activation of the membrane‐associated ERK2 via phosphorylation.
Protein degradation in red cells exposed to 2,2′‐azo‐bis(2‐amidinopropane) derived radicals
Authors: Celedón G. , Lips V. , Alvarado C. , Cortés M. , Lissi E. A. , González G.
Published: July 2007

Extensive proteolysis is observed when red blood cells are exposed to free radicals produced in the thermolysis of 2,2′‐azo‐bis(2‐amidinopropane). It is evaluated that nearly one amino terminal group is produced by each free radical introduced into the system. These groups are considered to arise mainly from band 3 fragmentation due to the action of red cell proteinases. Protein fragmentation takes place prior to significant hemolysis or lipid peroxidation, as evaluated by thiobarbituric acid‐reactive substances measurements.
Prolactin‐induced expression of TATA‐less cyclin D3 gene is mediated by Sp1 and AP2
Authors: Yang Miao , Nomura Hideki , Hu Ying , Kaneko Satoshi , Kaneko Hiroshi , Tanaka Minoru , Nakashima Kunio
Published: July 2007

The TATA‐less cyclin D3 gene is stimulated by prolactin (PRL) in rat Nb2 T‐lymphocytes. DNA mobility shift assay and luciferase transfection analysis revealed that the gene has a potential promoter region, two enhancer domanins and a silencer region. The promoter region possessed three Sp1 sites and two AP2 sites, and both enhancer regions bad one AP2 binding site each. Analysis using oligonucleotide probes and purified AP2 protein has suggested that the expression of rat cyclin D3 gene is promoted by Sp1 and AP2 factors.
Comparison of bilirubin binding and other molecular properties of tile serum albumin of several mammalian species
Authors: Rashid Huma , Muzammil Salman , Tayyab Saad
Published: July 2007

In order to develop an animal model for in vivo testing of the displacing action of various drugs and for study of the bilirubin deposition in the brain, some molecular properties of the serum albumin from different species i.e. pig, cat, human, dog, sheep, guinea pig and rat were investigated. These albumins were found to have differences in molecular weight, Stokes radius and electrophoretic mobility. They also showed different bilirubin binding characteristics when studied by spectroscopy and fluorescence quenching. It is therefore, necessary to consider the species differences when results of animal experimentation are used as a basis for the investigation of human kernicterus.
Group specific antibodies against the putative AMP‐binding domain signature SGTTGXPKG in peptide synthetases and related enzymes
Authors: Etchegaray Augusto , Dieckmann Ralf , Engel Paul C. , Turner Geoffrey , Döhren Hans
Published: July 2007

The superfamily of adenylate forming enzymes including peptide synthetases, acyl‐CoA synthetases and insect luciferases is readily identified by the signature sequence SGTTGXPKG. This sequence including an invariant lysyl residue is located in a disordered loop region and was predicted to be of significant antigenicity. Antibodies were generated employing YTSGTTGRPKGC attached to bovine serum albumin and have been successfully used to identify respective enzymes and adenylate forming domains in multienzyme systems. These include the δ‐(L‐α‐aminoadipyl)‐L‐cysteinyl‐D‐valine synthetases of Aspergillus nidulans and Acremonium chrysogenum, gramicidin S synthetase 1 and tyrocidine synthetase 1 from Bacillus brevis, acetyl‐CoA synthetase from Alcaligenes eutrophus and a putative peptide synthetase from Metarhizium anisopliae. Weaker or no reactions are observed when the amino acid in position X in the protein is non‐basic or hydrophobic, which is respectively the case for gramicidin S synthetase 1 and luciferase.
An archaeal DNA binding protein from thermophilic Sulfolobus acidocaldarius forms different types of complexes with DNA
Authors: Sreenivas Kanugula , Jaya K. S. , Suryanarayana Tangirala
Published: July 2007

We have characterized a DNA binding protein (DBNP‐B) from the thermoacidophilic archaeon Sulfolobus acidocaldarius with respect to its interaction with single and double stranded DNA. The protein in solution exists predominantly as dimer as indicated by cross linking studies. Binding of DBNP‐B to etheno DNA and poly (dA) resulted in fluorescence enhancement and hyperchromicity respectively. Ethidium bromide intercalated into DNA was completely displaced by DBNP‐B. DNase I digestion of dsDNA was increased at subsaturating concentration of the protein and was inhibited at higher concentrations. These results and electron microscopy indicate that the protein forms different types of novel complexes with DNA at different protein to DNA ratios.
Induction of buccal mucosal apoptosis with chronic alcohol ingestion
Authors: Slomiany B. L. , Piotrowski J. , Piotrowski E. , Slomiany A.
Published: July 2007

In this study we investigated buccal mucosal cells' apoptosis and the expression of regulatory cytokines, tumor necrosis factor‐α (TNF‐α) and inetrleukin‐4(IL‐4) with chronic ethanol ingestion. The buccal mucosa of rats maintained for 23 days on alcohol‐containing and control liquid diet was assessed for IL‐4 and TNF‐α content, and the extent of epithelial cells apoptosis. While the expression of TNF‐α in alcohol diet group showed a significant increase (1.9‐fold) over that of the controls, less apparent differences between the two groups were observed in the content of IL‐4 (141.8±28.2 vs. 119.8±7.3 pg/mg protein). The DNA fragmentation assays revealed that alcohol diet group also exhibited a 3.5‐fold enhancement in buccal mucosal cells apoptosis. Moreover, the apoptotic index showed positive correlation (r=0.53) with the extent of induced changes in TNF‐α. These results demonstrate that ethanol‐induced buccal mucosal cells apoptosis is triggered by the enhancement in TNF‐α expression.
Midkine induces histamine release from mast cells and the immediate cutaneous response
Authors: Hiramatsu Kenju , Yoshida Hiroshi , Kimura Tomoki , Takagi Kenzo
Published: July 2007

Midkine is a product of a retinoic acid‐responsive gene and exerts a variety of biological activities. The aim of our investigation is to determine whether human midkine have histamine‐releasing effects on mast cells, and to show the evidence of the inflammation induced by midkine. Midkine induced histamine release from rat peritoneal mast cells with a rapid response in a dose‐dependent manner. Extracellular calcium inhibited the histamine release induced by midkine in a dose‐dependent manner. Pertussis toxin and benzalkonium chloride inhibited the histamine release induced by midkine. Gi‐proteins exert an effect on the histamine release of midkine. The immediate cutaneous response induced by midkine was positive. These results suggest that midkine may take part in some inflammation via histamine release from mast cells.
Responses of intestinal and renal alpha‐glycosidases to alloxan and streptozotocin‐induced diabetes: A comparative study
Authors: Sharma Suresh D. , Sivakami S.
Published: July 2007

Experimentally induced diabetes in the rat resulted in an increased level of alpha‐glycosidases in the intestine but a depression in their levels in the kidney. Rat intestine exhibited a differential stimulation of maltase, sucrase and trehalase activities. The variations depended on the duration of diabetes and the β‐cytotoxic compounds used i.e. alloxan and streptozotocin. The maximum elevation in terms of total units and specific activity was observed on the 30th day in the following order: maltase>sucrase>trehalase. A significant observation emerging from this study is that the level of intestinal enzymes increases while that of the kidney enzymes declined during the period. Although intestinal and renal alpha‐glycosidases are known to be structurally and biochemically similar, their opposing responses to diabetes indicates that they are under different regulatory mechanisms in these tissues.
Partial characterization of the lipopolysaccharides of peanut specific Bradyrhizobium strains
Authors: Jayaraman Vani , Das Hasi R.
Published: July 2007

Hexoses, heptose, hexuronic acids, 2‐keto‐3‐deoxyoctonic acid (Kdo) contents of the lipopolysaccharides (LPS) isolated from peanut (A. hypogaea) specific Bradyrhizobium strains NC 92, IGR 92, IGR 40 and IGR 6 were found to vary considerably. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed a heterogenous LPS population and distinct heterogenity was observed in NC and IGR strains. Sepharose gel filtration chromatography removed the hexose contaminants from NC 92 LPS. Polysaccharides obtained by mild acid hydrolysis of Sepharose purified NC 92 LPS were further purified on Sephadex G‐50 gel filtration. Immunoblot analysis indicated cross reactivity amongst the peanut specific Bradyrhizobium strains but not with B. japonicum(SB 16). Antibodies raised against native NC 92 LPS showed higher binding towards the Sephadex purified polysaccharides suggesting the antigenic property of polysaccharide moiety in LPS molecule.
A proposed position of a disulfide bridge in the molecules of cinnamomin and porrectin ‐ two new type II ribosome‐inactivating proteins isolated from the seeds of camphor trees
Authors: Liu Wang‐Yi , Chen Huai‐Yang , Chen Wen‐Feng , Li Xiang‐Dong , Ulbrich Norbert , Schröder Werner
Published: July 2007

The N‐terminal amino acid sequences of A‐ and B‐chains of three isoforms of cinnamomin and porrectin ‐ two new type II ribosome‐inactivating proteins purified from the seeds of camphor trees have been compared with themselves and with that of ricin and abrin. It has completely homologous sequence of A‐chain of six isoforms, and the same of six B‐chain sequences. However, among 10 amino acids of the N‐terminal sequence of the A‐chain there is only 20% homology between cinnamomin/porrectin and abrin, no homology between cinnamomin/porrectin and ricin. In their B‐chain, there are 60% homology between cinnamomin/porrectin and ricin, the fourth position is always occupied by cysteine. Compared with that of ricin/abrin, we proposed that the position of a disulfide bridge is at fourth cysteine in the B‐chain of cinnamomin/porrectin and a cysteine nearby the C‐terminus of A‐chain of cinnamomin/porrectin.
An extremely high conservation of RNA‐protein S7 interactions during prokaryotic ribosomal biogenesis
Authors: Spiridonova Vera A. , Golovin Andrey V. , Drygin Denis Yu. , Kopylov Alexei M.
Published: July 2007

Direct determination of RNA‐protein complex structures is often facilitated by the use of thermophilic proteins; however E.coli is the most investigated system so far. A hybrid approach is to form heterologous complexes of E.coli RNA with thermophitic proteins. The rationale for this approach to RNA‐protein interactions in ribosomes is based on the ability of the thermophilic protein S7 to replace a homologous counterpart in vivo. In vitro, the protein S7 of Thermus thermophilus is able to form complexes with both the minimal 16S rRNA fragment and the intercistronic region of the str operon mRNA from E.coli (Kd=1.4×10‐7 M and 1.1×l0‐7 M respectively). The interaction of Thermus S7 with the E. coli intercistronic mRNA is surprising, because this region does not exist in the thermophilic str operon. It suggests a high degree of conservation of an RNA‐binding site on S7.
HPLC and light scattering detection allow the determination of phospholipids in biological samples and the assay of phospholipase A2
Authors: Landi Laura , Galli Maria Cristina , Cabrini Luciana , Hakim Gabriele , Carru Ciriaco , Fiorentini Diana
Published: July 2007

Some applications to biological samples of a method for the separation and the quantitative analysis of phospholipids by high performance liquid chromatography (HPLC) and light scattering mass detection are described. Results obtained in the determination of phospholipid classes from rat tissues such as liver, heart and kidney have been compared with data from the literature. The method has been applied to the evaluation of phospholipids in human low‐density lipoproteins (LDL), about which little is known. The procedure is also suitable for a rapid and reliable assay of the water‐soluble phospholipase A2 activity; the relationship between the aggregation state of substrate phospholipids (mixed micelles, multilamellar and unilamellar vesicles) and the enzyme activity has been studied.
Starvation induced hypothyroidism involves perturbations in thyroid superoxide‐sod system in pigeons
Authors: Prakash Prem , Laloraya Malini , Kumar G Pradeep
Published: July 2007

This study investigated the influence of starvation over seven days on avian thyroidal superoxide radical levels and superoxide dismutase activity profiles in the Indian rock pigeon Columba fivia intermeida, in relation with iodine metabolism. The serum thyroid hormone profile was assayed to correlate the thyroidal redox status with the circulating thyroid hormone levels. The spin‐trapping results suggest a role for thyroidal superoxide anion (O2‐) in causing a hypothyroid state in pigeons during long term energy withdrawal. Pigeons starved for 1 day generated superoxide and iodide free radicals in their thyroids, with a significant decrease in SOD activity. Regain of SOD activity in 2nd‐ and 3rd‐day starved birds is marked by complete scavenging of radicals in the thyroid, suggesting the significance of SOD in thyroid glands as a potential antioxidant sink against reactive oxygen species, O2‐. Resurgence of 02‐ radicals with a parallel decrease in SOD activity in the thyroid gland on 5th‐ and 7th‐day of starvation provides evidence of disruption of homeostasis between pro‐oxidant and antioxidant states, leading to oxidative stress in avian thyroid during long‐term calorie crisis. Following starvation both thyroid hormones thyroxine (T4) and triiodothyronine (T3) decreased, putting pigeons in a hypothyroidstate. We argue that oxidative inactivation of thyroid peroxidase and other thyroid proteins by radical attack during starvation invoked oxidative stress, which could be one of the factors responsible for the hypothyroid state in pigeons.
A novel method for selection of chymotrypsin inhibitors from a phage peptide library
Authors: Liu Ying , Li Bin , Zhang Shu , Li Tianyu , Zhou Hui , Li Wei , Smith Ross , de Jersey John
Published: July 2007

A novel screening strategy has been developed for the identification of α‐chymotrypsin inhibitors from a phage peptide library. In this strategy, the standard affinity selection protocol was modified by adding a proteolytic cleavage period to avoid recovery of α‐chymotrypsin substrates. After four cycles of selection and further activity assay, a group of related peptides were identified by DNA sequencing. These peptides share a consensus sequence motif as (S/T)RVPR(R/H). Then, a corresponding short peptide (Ac‐ASRVPRRG‐NH2) was synthesized chemically and proved to be an inhibitor of α‐chymotrypsin. The present work provides a useful way for searching proteinase inhibitors without detailed knowledge of the molecular structure.
Acrosome reaction inducers impose alterations in repulsive strain and hydration barrier in human sperm membranes
Authors: Purohit Sharad B. , Laloraya Malini , Kumar Pradeep G.
Published: July 2007

Spin labeling studies of the lipophilic domains of human spermatozoa during capacitation and during acrosome reaction (AR) under the influence of selected AR‐inducers were performed. Significantly enhanced rotational function of molecules was obvious during capacitation, with no significant changes in membrane packaging or the lateral diffusion of molecules. The AR inducers appeared to restrict the rotational freedom of molecules, dramatically enhancing the lateral diffusion and ordering coefficients. A significant decrease in superoxide anion generation was observed in the acrosome reacted groups when compared to the non‐acrosome reacted groups. A high level of superoxide anion radical (O2‐) level maintained in capacitated spermatozoa would add to the Van der Waal's repulsive forces at the polar head of phospholipids, holding the membrane in strain where the molecular enjoy little freedom for lateral motion. A sudden drop in the levels of O2‐ in spermatozoa upon addition of AR inducers could abruptly release the local hydrophobic repulsive strain within the membrane. This loss of hydration barrier explains the observed enhancement in lateral diffusion profiles of lipids and the packaging of molecules. It is reasonable to assume that these phenomena could be amplified further by interplay of Ca2+ by modifying the local charge aggregation. Thus, we would conclude that AR inducers release the oxyradical load in capacitated spermatozoa, which would modify the repulsive strain and hydration barrier forces in the lipophilic domains permitting vesiculation of the membranes. It appears that various acrosome reaction inducers act as effectors of grossly similar physical alterations in sperm membranes and that the resulting signal cascades proceed through intercalating biochemical sequences.
60K gelatinase in involuting rat mammary gland is produced as a 90K proenzyme
Authors: Ambili M. , Sudhakaran P. R.
Published: July 2007

The matrix metalloproteinases appear to play a key role in mammary tissue remodeling during involution. By immunoprecipitation and immunoblot using antibodies against 60K gelatinase which appears during involution, a 90K polypeptide has been identified as its inactive proenzyme in the early involuting rat mammary gland. 90K polypeptide was isolated from the second day involuting rat mammary gland by immunoaffinity chromatography. On proteolytic digestion, the inactive 90K polypeptide was converted to active gelatinase. Primary cultures of mammary epithelial cells secreted the 90K polypeptide. These results indicated that the 60K inducible MMP involved in mammary gland involution and remodeling is produced as a 90K proenzyme which is activated by proteolysis in the extracellular sites.
Cloning and characterization of the upstream region of Clostridium botulinum type B neurotoxin gene
Authors: Yang Gi‐Hyeok , Rhee Sang Dal , Jung Hyun Ho , Jhee Ok Hwa , Yang Kyu‐Hwan
Published: July 2007

The upstream region of the gene coding for Clostridium botulinum type B (BoNT/B) neurotoxin was cloned and sequenced. There were two open reading frames, which were identified as a nontoxic‐nonhemagglutinin component (ntnh/B) and a 22 kDa adjacent open reading frame (orf22/B). Deduced primary structure of ntnh/B showed that it was composed of 1,197 amino acid residues. Pairwise comparisons of the ntnh/B component with other botulinum toxin types showed high degree of homology to ntnh/A (82% identity). Northern blot analysis revealed that toxin gene could be transcribed alone or co‐transcribed with the ntnh gene. The orf22/B gene encoding for 178 amino acids (M.W. 21.6 kDa) was located between the 33 kDa hemagglutinin gene and the ntnh gene. Orf22/B also showed high degree of homology to orf22/A (98.9% identity). These results suggested that the upstream region of the BoNT/B gene (containing the ntnh/B and orf22/B genes) might be evolutionarily closely related to the counterparts of the BoNT/A.
Isolation of two chymotrypsins from grass carp
Authors: Fong Wing‐Ping , Chan Elaine Yee‐Man , Lau King‐Kwan
Published: July 2007

Two chymotrypsins were purified from the hepatopancreas of grass carp (Ctenopharyngodon idellus) by chromatographies on phenyl‐Sepharose and Q‐Sepharose. The molecular weights of chymotrypsins I and II were 28 and 27 kDa, respectively. The two chymotrypsins showed similar susceptibility to inhibitions by phenylmethylsulfonyl fluoride and soybean trypsin inhibitor, but differed in their response to tosyl‐L‐phenylalanine chloromethyl ketone and aprotinin in which chymotrypsin I was more resistant. Chymotrypsin I was a less typical chymotrypsin and exhibited lower catalytic efficiency with the chymotrypsin‐specific ester and amide substrates, when compared with chymotrypsin II. For both chymotrypsins, optimal activity was detected in the pH range 7.0‐8.5.
Dual effect of 2‐deoxy‐D‐glucose tetraacetate upon glucose‐induced insulin release
Authors: Malaisse Willy J. , Flores Luis E. , Kadiata Marcel M.
Published: July 2007

The effect of 2‐deoxy‐D‐glucose tetraacetate upon glucose‐stimulated insulin release was explored in pancreatic islets from either normal or hereditary diabetic rats. At a high concentration (10 mM), it decreased the secretory response to D‐glucose, such an inhibitory effect being more marked in the case of the α‐ than β‐anomer of the ester. At lower concentrations (0.19 to 1.7 mM), however, 2‐deoxy‐D‐glucose tetraacetate augmented insulin secretion evoked by 8.3 mM D‐glucose, with again a preference for the α‐anomer of the ester. In relative terms, such an enhancing action was more marked in Goto‐Kakizaki than normal rats. Hence, it is proposed that selected esters of non‐nutrient carbohydrates could be used as insulinotropic tools in the treatment of non‐insulin‐dependent diabetes mellitus.
Involvement of ras and map kinase (ERK‐1) in cisplatin‐induced activation of murine bone marrow‐derived macrophages
Authors: Shishodia Shishir , Sodhi Ajit , Shrivastava Anju
Published: July 2007

Cisplatin (cis‐diamminedichloroplatinum II), a potent antitumor compound, stimulates immune responses by activating monocytes/macrophages and other cells of the immune system. However, the mechanism by which cisplatin activates these cells is poorly characterised. Our earlier findings indicate that cisplatin treatment stimulates rapid tyrosine phosphorylation in a number of cellular proteins in murine macrophages. This initial tyrosine phosphorylation is an important regulatory mechanism and is followed by activation of several other proteins. In the present study, we report the involvement of other key molecules and the role of tyrosine phosphorylation in their activation in the signaling cascade of cisplatin. We observed the involvement of Ras (a low molecular weight GTP‐binding protein) and ERK‐1 (a MAP kinase) in this signaling cascade. Cisplatin treatment results in an increase in the expression of both Ras and ERK‐1 in a dose‐dependent manner, which was dependent upon tyrosine phosphorylation. Genistein a PTK inhibitor inhibited the cisplatin induced expression of Ras and ERK‐1. These findings indicate that Ras and ERK‐1 are important signaling molecules involved in the tumoricidal activation of macrophages with cisplatin and is dependent on initial tyrosine phosphorylation.
Inhibition of proton transport through spinach thylakoid membranes by 5,5′‐dithiobis(2‐nitrobenzoate)
Authors: Ho John W. , Ho Alex W.
Published: July 2007

In both oxidative phosphorylation and photo‐phosphorylation, electron flow through a carrier is linked to the generation of ATP. The energy released by electron transport is converted to potential energy forming a proton gradient across the membranes in chloroplasts. The proton gradient can be measured by a pH microelectrode. In this report, pH changes produced by photo‐induced proton transport through spinach chloroplast membranes were measured by a glass microelectrode. The effect of 5,5′‐dithiobis(2‐nitrobenzoate) (DTNB) on the kinetics of proton movement across the thylakoid membranes was studied. The results showed that the rate of proton uptake was reduced with increasing DTNB concentration. The rate of leakage of accumulated protons through thylakoid membranes also decreased. The results support the notion that cysteinyl residue is involved in proton translocation. The inhibition of proton transport would subsequently affect the chemical reactions of the Calvin Cycle that takes place in the stroma which is the soluble compartment surrounding the thylakoid membranes.
The absence of strand‐specific repair for the DNA polymerase pol gene in Deinococcus radiodurans
Authors: Lin Chan‐Shing , Wang Hsiu‐Chin , Wong Tit.Yee. , Liu Jong‐Kang
Published: July 2007

Deinococcus radiodurans is characterized by its extreme resistance to ionizing radiation. Although Mn+2 was taken up by the cells at a high speed, the absorption of Mn+2 by the cells did not affect their survival rate when irradiated by UV light. However, the Mn‐induced‐cell‐division (Mn‐CD) cells do lose their resistance to UV radiation. This can be explained by the fact that the Mn‐CD cells were less efficient to remove pyrimidine dimers on damaged DNA. We also found that there is no strand‐specific repair of the pol gene in this organism.
Effects of estradiol and progesterone on cytochrome P4501A1 expression in Hepa 1c1c7 cells
Authors: Lee Sang Seop , Jeong Hye Gwang , Yang Kyu‐Hwan
Published: July 2007

The effects of estradiol and progesterone on the expression of cytochrome P4501A1 were investigated in Hepa lclc7 cells. Both steroids, at 10 μM concentration, increased P4501Al‐mediated 7‐ethoxyresorufin O‐deethyalase activity and amounts of its immunoreactive protein and CYP1AI mRNA Gel shift assay revealed that the steroids could induce both AhR transformation and binding of the ligand‐AhR complex to its specific DNA recognition site. Transient transfection demonstrated that 5′flanking region of CYP1A1 could respond to the steroid action. The competitive binding assay showed that the steroids bound to AhR with moderate affinity. These results suggested that steroidal structure can be AhR ligands and induce CYP IAI expression in AhR‐dependent manner.
Inhibition of lung surfactant secretion by KN‐62, a specific inhibitor of the calcium‐ and calmodulin‐dependent protein kinase II
Authors: Liu Lin
Published: July 2007

A role of Ca2+‐ and calmodulin‐dependent protein kinase II (CaMK II) in lung surfactant secretion was evaluated using KN‐62, a specific inhibitor of CaMK II. KN‐62 caused a dose‐dependent inhibition of Ca2+ iononphore A23187‐stimulated phosphatidylcholine (PC) secretion from cultured alveolar type II cells. Concentration effecting 50% inhibition was ∼4 μM. However, KN‐62 only slightly influenced PC secretion from type II cells stimulated by phorbol 12‐myristate 13‐acetate, terbutaline and ATP that are known to increase surfactant secretion via the protein kinase C and protein kinase A pathways. KN‐62 also inhibited the activity of CaMK II in type II cells. A 55 kDa protein was detected in type II cells by Western blot analysis using an antibody against the β‐subunit of CaMK II. The results suggest that CaMK II participates in A23187‐stimulated lung surfactant secretion.
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

Homeostatic 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

Properties 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

The 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

Thiol 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

Recombinant 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

The 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

A 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

Different 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

A 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

In 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

Endothelins; (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

Advancing 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

In 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

The 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

Investigations 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

Cu,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

The 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.