bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of intersubunit cross‐linking on the conformational changes of creatine kinase during denaturation by guanidine hydrochloride
Authors: Zhu Li , Fan Ying‐xin , Zhou Jun‐mei 
Published: July 2007

AbstractIntersubunit cross‐linked creatine kinase (CK) has been prepared with the cross‐linking reagent dithiobis(succinimidyl propionate) (DTSP). Unfolding of cross‐linked CK during denaturation by guanidine hydrochloride (GuHC1), as monitored by intrinsic fluorescence, circular dichroism and fluorescence of the hydrophobic probe, 1‐aniline‐naphthalene‐8‐sulfonate (ANS), occurs in two stages with increasing GuHC1 concentration. The process is similar to that of the unmodified enzyme, but in the second stage, conformational changes of the cross‐linked enzyme need higher concentration of GuHC1, suggesting that there is a stable intermediate during its unfolding transition and the intermediate is stabilized by intersubunit cross‐linkage.
Cationic and secretory effects of 6‐O‐acetyl‐D‐glucose in rat pancreatic islets
Authors: Jijakli Hassan , Kirk Ole , Malaisse Willy J. 
Published: July 2007

AbstractSelected esters of D‐glucose were recently proposed as tools to supply the sugar to cells affected by a defect in the carrier‐mediated process of hexose transport across the plasma membrane. The present study extends this knowledge to 6‐O‐acetyl‐D‐glucose. At a 2.0 mM concentration, the ester was indeed found to stimulate insulin release from perifused rat pancreatic islets. This coincided with stimulation of calcium influx into the islet cells, as judged from comparison of the ester effects on 45Ca outflow from prelabelled islets perifused in either the absence or presence of extracellular Ca2+. The facilitated inflow of Ca2+ did not appear attributable to a decrease in K+ conductance, 6‐O‐acetyl‐D‐glucose augmenting 86Rb efflux from islets prelabelled with this radioactive cation. Both the latter phenomenon and the insulinotropic action of 6‐O‐acetyl‐D‐glucose failed to be antagonized by D‐marmoheptulose. These findings indicate that the cationic events coupling the recognition of D‐glucose to the stimulation of insulin release are not identical in islets exposed to the hexose or its ester.
Functional analysis of the evolutionary conserved arginine 182 residue in human glutathione S‐transferase P1‐1
Authors: Kong Kwang‐Hoon , Park Hee‐Joong , Takahashi Kenji , Inoue Hideshi 
Published: July 2007

AbstractThe mutational replacement of Arg182 with threonine markedly decreased the specific activities for GSH‐conjugation reaction. The kcat of R182T for GSH‐[1‐chloro‐2,4‐dinitrobenzene] conjugation reaction was about 100‐fold smaller than that of the wild type. On the other hand, the affinity for GSH of R182T was not significantly affected. The pKa of the thiol group of GSH bound in R182T was ∼0.9 pK units higher than those in the wild type, but the kcat/Km1‐chloro‐2,4‐dinitrobenzene values at high pH were not so much lower than those of the wild type. The thermostability of R182T was significantly lower than that of the wild type. Therefore, Arg182 seems to be important for the construction of the active enzyme structure.
Levels of interleukin‐6, CRP and α2 macroglobulin in cerebrospinal fluid (CSF) and serum as indicator of blood‐ CSF barrier damage
Authors: Kanoh Yuhsaku , Ohtani Hideki 
Published: July 2007

AbstractWe measured the levels of interleukin‐6 (IL‐6), albumin, C‐reactive protein (CRP) and α2 macroglobulin (α2M), all of which have different spectrums of molecular weight, in the cerebrospinal fluid (CSF) and serum in 121 patients to evaluate damage to the blood‐cerebrospinal fluid barrier (BCB) in meningitis. There was an extraordinary high level of IL‐6 in the CSF when patients had bacterial or viral meningitis, but the level returned to a normal range within a week in almost all of these cases. There were no significant differences in CSF albumin levels among the different disease groups. The CRP level in CSF is considered to correlate with the serum level, and CSF CRP was higher in bacterial meningitis than in viral meningitis, however, CRP in CSF was increased in some of the infectious diseases without meningitis. The α2M in CSF, which tends to be at extraordinarily high levels when there is damage to the BCB, correlated highly with CSF cell counts. CSF IL‐6 seemed to be a useful indicator to identify the acute active phase of meningitis. CRP and α2M in CSF are considered to be useful to differentiate bacterial meningitis, bacterial infection without meningitis and viral meningitis. Extraordinarily high levels of α2M, which has a high molecular weight, in CSF is indicative of BCB damage.
Integrin expression and collagenase activity of RSV‐transformed Syrian hamster fibroblasts, differing in spontaneous meatstasizing
Authors: Kozlova N. I. , Morozevich G. E. , Soloveyva N. I. , Vinokurova S. V. , Berman A. E. 
Published: July 2007

AbstractThe expression of extracellular matrix (ECM) specific receptors, integrins, and the activities of type IV collagenase and interstitial collagenase were investigated in two strains of oncogenically transformed fibroblasts, drastically differing in spontaneous metastasizing. Both strains were shown to express quite limited patterns of integrins. Of those, α5β1 integrin is greatly reduced on highly metastatic (HM) cells, while the expression of αvβ3 is strongly suppressed on lowly metastatic (LM) fibroblasts. No differences between the strains were found in either intracellular or secreted activities of type IV collagenase, while the activity of interstittial collagenase, secreted by HM cells, was twice as much as secreted by LM cells. The results imply the role of cooperated modifications of integrin‐directed cell‐ECM interaction and collagenase activity in establishing a metastatic phenotype.
Characterization of a beta‐lactamase from Mycobacterium smegmatis SN2
Authors: Basu Dhiman , Narayankumar D. V. , Van Beeumen Josef , Basu Joyoti 
Published: July 2007

AbstractBeta‐lactamases have been reported to be largely responsible for beta‐lactam resistance in Mycobacteria. We report the characterization of a cell‐associated beta‐lactamase from Mycobacterium smegmatis. The enzyme hydrolyzed the “beta‐lactamase‐stable” oximinocephalosporins. Nitrocefin was the best substrate. 6‐Beta‐iodopenicillanate, clavulanate and sulbactam were effective inhibitors, whereas the Ki value for aztreonam was high. From its substrate and inhibitor profile, the enzyme appeared to be a cephalosporinase of group 2e.
Regulation of CREB phosphorylation by cAMP and Ca2 in parotid acinar cells
Authors: Takuma Taishin , Tajima Yoshifumi , Ichida Tokuro 
Published: July 2007

AbstractSince various secretory stimuli regulate not only secretion but also protein, RNA, and DNA syntheses in salivary glands, we evaluated the effect of secretory stimuli on the phosphorylation state of CREB (cAMP response element‐binding protein). Isoproterenol, forskolin, and CPS‐cAMP markedly stimulated the phosphorylation of CREB in parotid acinar cells, and PKA inhibitors H‐8 and H‐89 dose‐dependently inhibited it. In contrast, carbachol (CCH) and A23187 decreased CREB phosphorylation, but CCH did not decrease it in the absence of extracellular Ca2+. Although protein phosphatase inhibitor calyculin A alone markedly increased the phosphorylation, it could not prevent CCH‐induced dephosphorylation of CREB. CaM kinase IV, a putative protein kinase for CREB in response to Ca2+ elevation, was undetectable in parotid acinar cells.
Differential inhibition of aflatoxin B1 oxidation by gestodene action on human liver microsomes
Authors: Kim Bok Ryang , Oh Hyun Sook , Kim Dong‐Hyun 
Published: July 2007

AbstractHuman cytochrome P450 (P450) 3A is known to be involved in the formation of both aflatoxin B1‐exo‐8,9‐epoxide (exo‐epoxidation) and aflatoxin Q1 (3α‐hydroxylation). Gestodene, a known inactivator of P450 3A4, inhibited the formation of AFB1 metabolites in a variety of ways depending on the incubation condition. Preincubation of gestodene with human liver microsomes prior to the addition of AFB1 inhibited both exo‐epoxidation and 3α‐hydroxylation whereas simultaneous incubation of gestodene with AFB1 only inhibited 3α‐hydroxylation. These results suggest that two independent substrate binding sites exist in P450 3A4, and AFB1 binds to both of the binding sites. Gestodene selectively binds to one of the binding sites leading to the formation of AFQ1, whereas it does not affect the formation of exo‐epoxide via the other binding site.
Effect of polyglutamate on the thermal stability of ferricytochrome c
Authors: Bágel'ová Jaroslava , Antalík Marián , Tomori Zoltán 
Published: July 2007

AbstractThe effect of saturated solutions of polyglutamate on the thermal stabilities of the Met‐80‐heme iron bond and of the ferricytochrome c as a whole were studied by absorption spectroscopy and differential scanning calorimetry at pH 7.0. According to spectral data the midtransition temperature of the cleavage of the sulfur‐iron bond was 57.4±0.5 °C and 66.8±0.5 °C for cytochrome c and cytochrome c‐polyglutamate complex, respectively. Addition of polyglutamate to cytochrome c at pH 7.0 alters the denaturation properties of the protein. As follows from DSC scans, the denaturation temperature for cytochrome c is decreased from 85.4±0.2 °C to 68.7±0.2 °C in the presence of the saturated amount of polyglutamate. The protein stability in terms of Gibbs energy change at protein unfolding amount to ΔG(25°C)=22.7±2.7 and 32.0±2.2 kJ/mol, for cytochrome c and cytochrome c‐polyglutamate complex, respectively, at pH 7.0. It is evident that polyglutamate increases the thermal stability of the sulfur‐iron bond and decreases the denaturation temperature of the cytochrome c molecule as a whole. The complex thermal stability in terms of Gibbs energy is not lower than that of cytochrome c in the range of physiological temperatures.
Inhibition of the proliferative effect of transforming growth factor‐α by c‐myc antisense DNA in human ovarian cancer cells
Authors: Park Hae‐Young 
Published: July 2007

AbstractIn search of critical genes associated with the mechanism of transforming growth factor‐α (TGFα) action in human ovarian cancer, it was found that TGFα stimulates c‐rnyc gene expression in human ovarian NIH:OVCAR‐3. The role of c‐myc in TGFα‐stimulated growth of NIH:OVCAR‐3 cells was examined by the use of the synthetic antisense‐myc phosphorothioate oligonucleotide (OPT). Prior exposure of NIH:OVCAR‐3 cells to an antisense‐myc OPT inhibited TGFα‐stimulated cell growth and DNA syntbesis in a dose‐dependent and sequence‐spocific manner over 4 days. c‐Myc protein expression was down‐regulated in the antisense‐myc treated cells. These results demonstrate both the specific and durable effects of the antisense‐myc OPT. Furthermore, the results suggest a role for c‐myc in TGFα‐stimulated cell proliferation.
Fatty acid composition of brown adipose tissue in dietary obese rats
Authors: Lladó Isabel , Pons Antoni , Palou Andreu 
Published: July 2007

AbstractThe effects of both dietary obesity and a food deprivation period of 24 hours on fatty acid composition of brown adipose tissue have been investigated. Long time exposure to a hypercaloric high‐fat diet such as the cafeteria diet induced an important tissue fatty acid accumulation, mainly for the major saturated and monounsaturated fatty acids. Notable metabolic differences have been observed in the behaviour of control and obese rats facing a food deprivation period: a preferential utilization of the most abundant saturated fatty acids in control rats and a minor response in obese rats, with a greater fat accumulation in the interscapular brown adipose tissue.
Evidence for the transfer in culture of [14C]‐labelled fatty acids from macrophages to lymphocytes
Authors: Peres C. M. , de Bittencourt P.I. Homem , Costa M. , Curi R. , Williams J. F. 
Published: July 2007

Abstract[14C]‐labelled palmitic acid (PA), oleic acid (OA), linoleic (LA) and arachidonic (AA) acids were transferred from macrophages (Mφ) to lymphocytes (LY) when equal numbers of the two cell types were co‐cultured. The relative degree and amounts of the fatty acids transferred from Mφ to LY are as follow: AA (368.57±21.62)=OA (274.52±15.41)>LA (42.11±8.31)=PA (36.53±2.45). The transfer units are nmol/1010 Mφ/1010 LY and the values are mean±SEM for 7 experiments. The [144C]‐radioactivity transferred was mainly directed to the phospholipid fraction of the lymphocytes (85% by PA, 86% by LA, 83% by OA and 79% by AA). In the same order as above, phosphatidylcholine was the phospholipid moiety most heavily labelled (82% by PA, 71% by LA, 66% by OA and 47% by AA). The amount of [14C]‐radioactivity transferred to stimulated lymphocytes of thioglycollate treated animals remained unchanged for LA, PA and AA but reduced for OA (71%). The significance of these observations for the immune functions of the cells and resolution of the question of whether some of the [14C]‐isotope transfer involves a component of exchange or is unequivocally net fatty acid mass transfer are still being investigated.
Quantification of prostaglandin D synthetase in cerebrospinal fluid: A potential marker for brain tumor
Authors: Saso Luciano , Leone Maria Grazia , Sorrentino Claudio , Giacomelli Sabrina , Silvestrini Bruno , Grima Josephine , Li Jonathan C. H. , Samy Eileen , Mruk Dolores , Cheng C. Yan 
Published: July 2007

AbstractProstaglandin D synthetase (PGD‐S; prostaglandin‐H2 D‐isomerase, EC 5,3,99,2), a 30 kDa glycoprotein also known as β‐trace protein that catalyzes the formation of prostaglandin D2 (PGD2) from PGH2, was purified to apparent homogeneity from human cerebrospinal fluid (CSF) using a two‐step procedure involving HPLC on a Vydac C8 reversed‐phase column and high performance electrophoresis chromatography (HPEC) using a 10% T SDS‐polyacrylamide gel. The purity of PGD‐S isolated from CSF was confirmed by silver stained SDS‐polyacrylamide gel and direct protein microsequencing (NH2‐APEAQVSVQPNFQ). A highly specific polyclonal antibody was prepared against this protein for immunoassay development. Using an ELISA, it was found that the concentration of PGD‐S in CSF did not alter significantly in different pathological conditions of the central nervous system (CNS). These include dementia (n=9), hydrocephalus (n=4), neuropathy (n=11), optic neuritis (n=4), multiple sclerosis (n=11), and demyelinating syndrome (n=11), when compared to normal individuals (n=12); however, the level of PGD‐S in the CSF obtained from patients with brain tumor (n=11), was reduced by as much as 2‐fold when compared to control samples (n=12) illustrating PGD‐S is a potentially useful marker for brain tumor.
Relationship between rate and extent of catechin absorption and plasma antioxidant status
Authors: Pietta Piergiorgio , Simonetti Paolo , Gardana Claudio , Brusamolino Antonella , Morazzoni Paolo , Bombardelli Ezio 
Published: July 2007

AbstractFlavonoids are described to exert a large array of biological activities, which are mostly ascribed to their radical‐scavenging, metal chelating and enzyme modulation ability. Most of these evidences have been obtained by in vitro studies on individual compounds and at doses largely exceeding those dietary. Little is known about a possible relationship between rate and extent of the absorption and modifications of plasma antioxidants. To elucidate this aspect, human volunteers were supplemented with single doses of green tea catechins in free (Greense‐lect™) or phosphotipid complex form (Greenselect™ Phytosomer®) equivalent to 400 mg epigallocatechingallate (EGCg). EGCg was chosen as biomarker for green tea catechin absorption, and its time course plasma concentration was correlated to the subsequent percent variations of plasma ascorbate, total glutathione, α‐tocopherol, β‐carotene and Total Radical Antioxidant Parameter (TRAP). Green tea catechins were absorbed more extensively when administered as phospholipid complex rather than as free catechins. Single dose intake of both forms of catechins produced a transient decrease (10‐20%) of plasma ascorbate and total glutathione and an increase of plasma TRAP (16‐19%). These variations were consistent with the plasmatic levels of EGCg, ascorbate and total glutathione.
The carboxyl‐terminal fragment of osteopontin suppresses arginine‐glycine‐asparatic acid‐dependent cell adhesion
Authors: Takahashi Kazuhisa , Takahashi Fumiyuki , Tanabe Kenneth K. , Takahashi Hideki , Fukuchi Yoshinosuke 
Published: July 2007

AbstractOsteopontin (OPN) is a secreted glycoprotein implicated in cell adhesion. It contains the arginine‐glycine‐asparatic acid (RGD) cell adhesive domain and the thrombin cleavage sequence. Although thrombin cleavage of OPN has been shown to be of physiological importance, the function of C‐terminal OPN fragment cleaved by thrombin remains unknown. To determine its role, we performed cell adhesion assays using glutathione S‐transferase‐OPN fusion protein fragments and full‐length OPN fusion protein. The N‐terminal fragment containing RGD motif promoted enhanced adhesion of mouse and human fibroblasts by 2.9 and 2.8 folds in comparison with full‐length OPN, respectively. The enhanced adhesion of both cells mediated by N‐terminal fragment was significantly suppressed by addition of C‐terminal fragment lacking RGD motif that has less cell adhesive property than full‐length OPN. These results suggest that the C‐terminal domain may play a pivotal role in regulating OPN functions by suppressing the RGD‐dependent cell adhesion.
Human milk lactoferrin binds ATP and dissociates into monomers
Authors: Semenov Dmitry V. , Kanyshkova Tatyana G. , Buneva Valentina N. , Nevinsky Georgy A. 
Published: July 2007

AbstractThe physiological role of lactoferrin (LF) is still unclear, but it has been suggested to be responsible for primary defence against microbial infections. Many different unique functions have been attributed to LF, including DNA and RNA binding, and transport into the nucleus, where LF binds to specific DNA sequences and activates transcription. Here we present evidence that in addition to the above (and below) mentioned functions LF binds ATP with a stoichiometry of 1 mole of nucleotide per mole of the protein and a Kd=0.3 mM. The ATP‐binding site is localized in the C‐terminal domain of LF, in contrast to the antibacterial and polyanion‐binding sites, which are located in the N‐terminal domain. Binding of ATP by LF leads to dissociation of its oligomeric forms and to a change of the protein's interaction with polysaccharides, DNA and proteins.
Transcriptional regulation of the CDK inhibitor p16INK4a gene by a novel pRb‐associated repressor, RBAR1
Authors: Kaneko Satoshi , Nishioka Junji , Tanaka Minoru , Nakashima Kunio , Nobori Tsutomu 
Published: July 2007

Abstractp16, also known as INK4a, CDKN2, or MTS1, plays an important role in the control of the cell cycle progression, and retinoblastoma protein (pRb) is suggested to be involved in the transcriptional regulation of p16. However, it is not fully understood how pRb regulates transcription of the p16 gene. Nuclear proteins prepared only from the pRb‐nonfunctional human tumor cells were found to bind to the 5′‐flanking sequence of the p16 gene in the presence of Zn2+ by electrophoretic mobility shift assay (EMSA). EMSA using mutagenized 5′‐flanking sequences as competitors suggested that the sequence at position ‐97 to ‐87 relative to first ATG of the p16 gene was critical for protein binding. Transient reporter assay indicated that the sequence identified by EMSA acted as a silencer element in the pRb‐nonfunctional tumor cells, showing the presence of a transcriptional repressor associated with functional pRb (RBAR1).
Effects of sulfhydryl compounds on the inhibition of erythrocyte membrane Na ‐K ATPase by ozone
Authors: Bilgin Ramazan , Gül Sermin , Tükel S. Seyhan 
Published: July 2007

AbstractExposure of human erythrocyte membranes to ozone (5 μmol/10 min) resulted in the inhibition of erythrocyte membrane Na+‐K+ ATPase (EC.3.6.1.39). It was determined that, the degree of enzyme inhibition in the directly ozone exposed membranes was greater than that of membranes obtained from ozone exposed intact erythrocytes. In the presence of varying concentrations (0‐1.0 mM) of dithiotrethiol or mercaptoethanol Na+‐K+ ATPase activities of both types of ozone exposed membranes were increased almost proportionally with the concentration of dithiotrethiol or mercaptoethanol however, the activities were still lower than the normal Na+‐K+ ATPase value.The results indicate that, dithiotrethiol or mercaptoethanol prevent the enzyme inhibition by ozone in vitro. This suggests that the membrane thiol groups are primary targets for ozone and thereby preventing the oxidation of essential functional groups of enzyme, protein.
Cloning and expression of bovine herpesvirus‐1 glycoprotein C
Authors: Gupta Praveen K. , Saini Mohini , Gupta L. K. , Bandyopadhyay S. K. , Garg S. K. 
Published: July 2007

AbstractGlycoprotein C (gC) of Bovine Herpesvirus‐1 (BHV‐1) is expressed at high levels on surface of infected cells and on virus envelope. It is relatively immunodominant in antibody response to BHV‐1 infection and protective in immunized bovines against BHV‐1 challenge. In an attempt to express gC in mammalian cells, the 2.4 kb BamHI‐EcoRI fragment, containing complete coding sequence of the gC gene was excised from a recombinant plasmid and cloned under the control of RSV‐LTR. The resultant plasmid pRSV‐gC was transfected into MDBK cells and expression of gC was detected by indirect immunofluorescence. The non‐permeabilized cells revealed surface expression of gC.
20S proteasome, hsp90, p97 fusion protein, PA28 activator copurifying oligomers and ATPase activities
Authors: Montel Valérie , Gardrat Florence , Azanza Jean‐Louis , Raymond Jacques 
Published: July 2007

AbstractWhether hsp90 acts in an ATP‐depeadent or independent way is of crucial importance for understanding the molecular mechanism of this chaperone and, to day, the involvement of ATP hydrolysis in hsp90 function is still a contreversial subject. ATPase activities may be detected in partially purified hsp90′s preparations from rabbit muscle. We demonstrate that the major contaminant associated with hsp90 is the p97 fusion protein and that these oligomeric structures are copurifying together with the 20S proteasome and its PA28 activator. Improving the purification procedure permits to separate hsp90 and p97 to homogeneity. Then, our attempts failed to detect any significant ATPase activity in the hsp90 fraction. Thus, p97 would be principally responsible for the ATPase activity detected in partially purified hsp90 preparations from rabbit muscle.