bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen Transport and Exchange in the Microcirculation
Authors: PITTMAN ROLAND N. 
Published: July 2007

ABSTRACTThe cardiovascular system is responsible for maintaining an adequate convective delivery of oxygen to the smallest branches of the network of blood vessels—the microcirculation—from which oxygen passes to the parenchymal cells by passive diffusion. The aim of this brief review is to trace the development of the study of oxygen transport from the point of view of the microcirculation. August Krogh performed measurements that allowed him to use his keen insight to draw conclusions about oxygen transport that remained the foundations of this field for decades. After an extended period of neglect, Duling rekindled interest in the field of oxygen transport by discovering that substantial amounts of oxygen diffused from the arteriolar network. Subsequent investigations confirmed this finding in various vascular beds and extended these studies to capillaries and venules. The important contributions of computational modeling and new techniques in intravital microscopy continue to led to more advances in our understanding of the role of the microcirculation in the supply of oxygen to tissues. Current work is applying the concepts and principles learned in normal tissues to pathophysiological situations, as well as increasing our understanding of artificial oxygen carriers, oxygen sensing, and the connections between nitric oxide and oxygen transport.
Therapeutic Intervention in Inflammatory Diseases: A Time and Place for Anti‐Adhesion Therapy
Authors: NORMAN M. URSULA , KUBES PAUL 
Published: July 2007

ABSTRACTThe recruitment of leukocytes from the blood into tissue is central to the development and maintenance of the majority of inflammatory diseases. This multistep process requires a series of leukocyte–endothelial adhesive interactions, involving several families of adhesion molecules. Molecules that block these interactions have been targeted as potential therapeutic treatments for acute and chronic inflammatory diseases. However, many of the anti‐adhesion therapy clinical trials have yielded disappointing outcomes. This review discusses some of the animal models that raise questions about the suitability of anti‐adhesion therapy to treat certain inflammatory diseases. The authors suggest that it is crucial to understand the underlying mechanisms and timelines of leukocyte recruitment in each affected tissue and inflammatory disease to develop more effective anti‐adhesion therapy.
Irreversible inactivation of Caldariomyces fumago chloroperoxidase by hydrogen peroxide
Authors: Shevelkova Angelina N. , Ryabov Alexander D. 
Published: July 2007

AbstractThe rate constants for the H2O2‐induced irreversible inactivation (kinact) of chloroperoxidase from Caldariomyces fumago evaluated from the analysis of complete kinetic curves of chlorination or bromination of monochlorodimedon were found to follow the rate law kinact = k[H2O2]/(K + [H2O2]) with k = 0.009±0.002 and 0.0095±0.0010 s‐1 and K = (13±4)×10‐3 and (9±2)×10‐3 M in the presence of 0.01 M chloride and bromide, respectively, at pH 2.75 and 25 °C. The data show that chloroperoxidase investigated is more than by a factor of 10 less resistant toward hydrogen peroxide compared to horseradish peroxidase. The possible reason for it and the biotechological implications are briefly discussed.
Coordination of copperpolyamine complex with imidazoles potentiates its superoxide dismutase mimicking activity and abolishes its interaction with albumin
Authors: Athar Mohammad , Sharma Som D. , Iqbal Mohammad , Sultana Sarwat , Pandeya K. B. , Tripathi I. P. 
Published: July 2007

AbstractMixed ligand complexes of copper polyamine with biomolecules such as imidazole, substituted imidazoles or pyridine have been synthesized and characterized. These molecules were used because of their low toxicity and high activity. These complexes were found to possess a distorted octahedral microenvironment with a potential SOD mimicking activity. The IC50 values for these complexes were of the order of 2‐90 μM. Pyridine and imidazole complexes were most effective as they possess the lowest IC50 values of 2.1 and 6 μM respectively which are higher than the IC50 value of polyamine copper complex. Based on the uric acid estimations, it has also been ascertained that these complexes dismute O2.‐ without inhibiting xanthine oxidase activity. The presence of increasing concentrations of albumin had no effect on the SOD mimicking activity of mixed ligand complexes. Polyamine complex, however lost approximately 80% of SOD mimicking activity in the presence of albumin (1 mg). These results suggest that coordination of polyamine copper complex with imidazoles/pyridine may abolish their binding affinity for albumin while potentiating their SOD mimicking activity.
Use of transport mutants to examine the identity and expression of GLUT isoforms in rat cardiac myoblasts
Authors: Lu Zhan , Zaniewska Ewa , Lo Theodore C. Y. 
Published: July 2007

AbstractTwo different spontaneous glucose transport (GLUT) mutants were used to examine the identity and properties of proteins involved in rat cardiac myoblast glucose transport processes. The parental clone, H9C2, possessed a high (HAHT) and a low (LAHT) affinity hexose transport process, and the GLUT 1, 3 and 4 isoforms. Mutant RCM was devoid of HAHT, the GLUT 3 transcript, and a 41 kDa protein recognizable by an anti‐mouse GLUT 3 Ab. Mutant EZ‐4 was impaired in the GLUT 3 and 4 isoforms, and in HAHT and LAHT. These studies demonstrated a close association of the GLUT 3 and 4 isoforms with the HAHT and LAHT processes, respectively. Both GLUT 3 and 4 isoforms were regulated in opposite ways during myogenesis, and both GLUT 3‐ mutants were impaired in myogenesis. Despite its normal GLUT 1 transcript level, mutant EZ‐4 was devoid of an efficient carrier‐mediated glucose transport process, thus suggesting that the GLUT 1 transporter was inoperative in rat cardiac myoblasts. Unlike the rat skeletal L6 GLUT 1 isoform, expression of the rat cardiac GLUT 1 isoform was not affected by glucose starvation, and was not reduced in multinucleated myotubes. These studies demonstrated the usefulness of transport mutants in determining the identity, expression and property of GLUT isoforms and their association with specific transport processes.
Utilization of alcohols by plant and mammalian phospholipase D
Authors: Ella Krishna M. , Meier Kathryn E. , Kumar Anil , Zhang Yanzhi , Meier G. Patrick 
Published: July 2007

AbstractThe transphosphatidylation reaction is a unique property of phospholipase D (PLD). In this study, the abilities of plant and mammalian PLDs to utilize straight chain and branched alcohols for transphosphatidylation were analyzed and compared. PLD from peanut utilizes C1 to C8 primary alcohols and gives maximal reaction with butanol. In contrast, PLD from A7r5 vascular smooth muscle cells gives maximal reaction with pentanol and does not utilize octanol. Secondary and tertiary alcohols are not substrates for either enzyme. For branched alcohols, activity increases with distance from the alcohol to the branch point. Competition studies indicated that secondary alcohols cannot access the binding pocket. Thus, PLDs have a water/alcohol binding site with defined steric and hydrophobic parameters.
Involvement of a tyrosine residue in the ADP binding site of creatine kinase. A second‐derivative UV‐spectroscopy study
Authors: Leydier Chantal , Clottes Eric , Couthon Fabienne , Marcillat Olivier , Vial Christian 
Published: July 2007

AbstractSecond‐derivative spectroscopy was used to determine the percentage of tyrosine residues that are exposed to solvent in rabbit MM‐creatine kinase. Six residues, among the ten present per monomer, are solvent‐exposed. The presence of creatine in the incubation medium does not modify this value. However, this number is decreased by one when the enzyme is incubated with saturating concentrations of MgADP. A dissociation constant for MgADP can be estimated and the obtained value (0.085 mM) is comparable to the Km for this substrate. Thus, a tyrosine residue is located near the MgADP binding site or is masked during protein conformational change induced by adenyl nucleotide binding.
Glycolytic enzyme binding in Otala lactea hepatopancreas: Effect of taxol, colchicine and cytochalasin B and D on the in vivo enzyme distribution
Authors: Brooks S. P. J. , Storey K. B. 
Published: July 2007

AbstractThe effect of cytoskeleton modulators on glycolytic enzyme binding was examined in the hepatopancreas of Otala lactea in an attempt to identify potential cellular binding sites. Binding was followed by measuring phosphofructokinase (PFK), aldolase (ALD), glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) and pyruvate kinase (PK) distribution between low speed pellets (12,000xg), high speed pellets (100,000xg) and high speed supernatants. Taxol (which stabilizes microtubules), colchicine (which destabilizes microtubules) and cytochalasin B and D (which destabilize F‐actin filaments) were added to the homogenate prior to centrifugation. Addition of taxol increased the amount of PFK associated with the high speed pellet. Cytochalasin B and D reduced the binding of PFK and PK to the low speed pellet. ALD and GAPDH binding were unaffected by any treatment. Lowering the pH of the crude homogenate increased PFK binding to the low speed pellet by 33%. This effect could be reversed by addition of cytochalasin B and D suggesting that pH influences the PFK‐F‐actin interaction in vivo. The differential binding response of PFK, PK, ALD and GAPDH to added effectors suggests that, in the cell, PFK and PK are bound to different subcellular structural elements than are ALD and GAPDH.
Characterization of a 34 kDa immunoreactive peptide with the anti protein kinase C antibody which can recognize part of the C4 region
Authors: Ayaki Masako , Hashimoto Chieko , Inui Yukiharu 
Published: July 2007

AbstractAmong the immunoreactive peptides from hamster tissues with the antibody (Ab‐1) which can recognize part of the C4 conserved region of protein kinase C (PKC), a peptide with 34 kDa (34 kDa species) is constitutively detected in the soluble and the nuclear but not in the particulate fractions. The partially purified 34 kDa species demonstrates no phospholipid‐dependent or independent PKC activity and no phorbol 12,13 dibutyrate (PDBu) binding, and is not phosphorylated under the assay condition of PKC activity. The species inhibits the enzymic activity of the partially purified PKC from hamster brain in an uncompetitive manner with Ki of 200±23 nM.
Two pathways of the nitric oxide‐induced cytotoxycal action
Authors: Turpaev Kyril T. , Amchenkova Aleftina M. , Narovlyansky Alexander N. 
Published: July 2007

AbstractNitric oxide is a diffusible messenger with multiple biological functions. We show here that NO‐generating compound, S‐nitrosoglutathione (GSNO) induces apoptosis in human chondrocytes and causes necrosis‐like celt death in human epithelial CaOv cell line. Pretreatment of chondrocytes with low‐dose GSNO or with γ‐interferon enhances their tolerance to the second high‐concentration GSNO exposure. On the contrary, in CaOv cells low‐dose GSNO pretreatment diminishes the resistance and increases cytolysis at the second GSNO exposure. We conclude that human chondrocytes possess specific and inducible mechanism preventing celt killing by nitric oxide.
Characterization of a soluble IL‐6 receptor α mutant C277D/H280I expressed in E. coli
Authors: Duan Jubao , Wang Jiaxi , Cai Xin , Wang Lihong , Liu Haitian , Zou Minji 
Published: July 2007

AbstractThe pleiotropic cytokine interleukin‐6(IL‐6) triggers the formation of a high affinity receptor complex constituted by the ligand‐binding subunit IL‐6 receptor α(IL‐6Rα) and the signal transducer gpl30. To construct the antagonist of IL‐6, a DNA segment encoding the soluble human IL‐6Rα(shlL‐6Rα) mutant with two substitutions C277D/H280I was generated by overlap extension polymerase chain reaction. The DNA segment was then subcloned into vector pET‐3b and expressed in E.coli at a high level. The refolded and purified recombinant protein, which was designated as DM650, exhibited an increased IL‐6‐binding capability by 8‐fold. DM650 antagonized IL‐6 perfectly, resulting in the growth‐inhibition of human myeloma AF‐10 cells. DNA fragmentation assay proved that the growth of AF‐10 cells was inhibited through the induction of apoptosis suppressed by IL‐6.
The structural and functional essentiality of the N‐terminal α‐helix in the phospholipase A2 of the Taiwan banded krait
Authors: Chang Long‐Sen , Chang Chun‐Chang , Wu Pei‐Fung 
Published: July 2007

AbstractIn order to identify the structural and functional essentiality of the N‐terminal α‐helix of Bungarus multicinctus PLA2 for its enzymatic activity, comparative studies of the biochemical properties of native and recombinant PLA2 were made. It was found that the appearance of a Met residue preceding the N‐terminus Asn‐1 of the recombinant protein appreciably affected PLA2 activity and the hydrophobic character of the ANS‐binding site. Additionally, the charged state and the hydrophobicity of the molecular surface changed as well. However, removal of the N‐terminal Met‐1 from the recombinant PLA2 resulted in the production of a fully active PLA2, whose biochemical properties were indistinguishable from those of the native enzyme. These observations, together with the findings that the helical wheel plot of the N‐terminal α‐helix showed distinct hydrophobic and hydrophilic faces and that the ANS‐binding site was the active site of PLA2 enzymes, suggest that the hydrophobic face of the N‐terminal α‐helix in native PLA2 should be in the interior of the enzyme molecule for binding with ANS and the phospholipid/substrate.
DL‐propranolol negatively regulates the transcription of proliferating cell nuclear antigen (PCNA)‐gene and thereby suppresses DNA synthesis in regenerating rat liver
Authors: Hong Jeong‐Ho , Hwang Eun Sook , Lee Chang Ho , Lee Yong Hee , Lee Seung Ki 
Published: July 2007

AbstractPrevious reports have suggested that dl‐propranolol (PRL) suppresses DNA synthesis by blocking cAMP‐mediated signaling in rat liver after partial hepatectomy (PH). Here, we examined if PRL negatively regulates the expression of genes involved in cell cycle progression. Immunoblotting assays showed that the protein levels of cyclins A and E, Cdk2, p21WAF1, and p27KIP1 did not significantly change in liver tissues from either vehicle‐ or PRL‐injected rats after PH. However, the levels of PCNA and PCNA‐mRNA markedly decreased in the remnant liver in response to PRL‐injection. Similarly, PCNA‐CRE binding activity of nuclear 43kDa CREB was suppressed, although the protein levels were not altered. We suggest that PRL negatively regulates the PCNA‐gene transcription by interfering with the cAMP/PKA‐mediated induction of CREB binding to the CRE‐sequences and thereby suppresses DNA synthesis in regenerating rat liver.
Mutational analysis for the role of C‐terminal region of ecotin, a dimeric inhibitor of pancreatic serine proteases
Authors: Seong Ihn Sik , Lee Cheol Soon , Park Hye Kyung , Suh Se Won , Kang Man‐Sik , Chung Chin Ha 
Published: July 2007

AbstractEcotin is a dimeric molecule that is capable of inhibiting a variety of serine proteases. To clarify the role of the C‐terminal region, mutagenesis was performed to delete the C‐terminal residues from 130 to 142. The mutant inhibitor behaved as a monomer upon cross‐linking analysis followed by gel filtration. The mutation also resulted in a significant increase of the Ki of ecotin on trypsin, chymotrypsin, and elastase (i.e., by 1 to 2 order of magnitude). The mutant ecotin was slightly more sensitive to heating at 100°C than the wild‐type ecotin, but became much more sensitive to the heat treatment upon reduction of the intra‐chain disulfide bond in its subunits. In addition, treatment with 4 M urea resulted in complete loss of the activity of the mutant ecotin but not that of the wild‐type inhibitor. Thus, the C‐terminal region of ecotin seems to be required not only for dimerization of the subunits but also for optimal interaction with target proteases and for maintenance in its structural stability, particularly under reducing or denaturing conditions.
Linear gene fusions of antibody fragments with streptavidin can be linked to biotin labelled secondary molecules to form bispecific reagents
Authors: Pearce Lesley A. , Oddie Geoffrey W. , Coia Gregory , Kortt Alexander A. , Hudson Peter J. , Lilley Glenn G. 
Published: July 2007

AbstractMonomeric single chain antibody (scFv) fragments lack both the avidity of the bivalent IgG, or (Fab′)2 fragment, and the effector functions conferred by the Fc domain. For certain diagnostic or therapeutic applications it may be desirable to link these molecules to other proteins, antibodies, enzymes or peptide ligands, and chemical or recombinant methods have been developed to produce many of these crosslinked reagents. One approach has been to link an antibody fragment to streptavidin which can bind a second biotinylated molecule to create a higher affinity, bifunctional or bispecific molecule. To demonstrate the applicability of this technology, an anti‐neuraminidase NC10 scFv‐streptavidin fusion was expressed in E. coli and the product was refolded and purified to homogeneity from 6 M guanidine hydrochloride. Analysis in a BIAcoreTM biosensor showed that the NC10 scFv moiety reacted with immobilised neuraminidase and that the core streptavidin moiety was able to bind biotinylated anti‐ferritin Fab' to produce a new model bispecific reagent which bound ferritin. Conceptually, this design principle can be applied to the creation of useful diagnostic and possibly therapeutic molecules.
Involvement of caspases in apoptosis induced by ultraviolet B irradiation in A431 human epithelioid tumor cells
Authors: Iwasaki Kazumi , Izawa Masao , Mihara Motoyuki 
Published: July 2007

AbstractSix hours after ultraviolet B (UVB) irradiation (11.6 mJ/cm2), the viability of A431 cells decreased, and, at the same time, fragmentation of genomic DNA into nucleosomal units was observed. Z‐Asp‐CH2‐DCB (100 μM), an inhibitor of interleukin‐1 β‐converting enzyme (caspase‐1 ) and caspase‐1‐like proteases, markedly inhibited UVB‐induced cell death and DNA fragmentation. Both YVAD‐CMK, an inhibitor of caspase‐1, and DEVD‐CHO, an inhibitor of caspase‐3, moderately inhibited the UVB‐induced cell death. A combination of YVAD‐CMK and DEVD‐CHO acted additionally in inhibiting cell death. These observations suggest strongly the cooperative involvement of caspases in the apoptosis induced in A431 cells by UVB.
Isolation and characterization of 5′‐regulatory region of mouse activin ßa subunit gene
Authors: Yoshida Eisaku , Tanimoto Keiji , Murakami Kazuo , Fukamizu Akiyoshi 
Published: July 2007

AbstractWe isolated genomic clones that contain the 5′‐flanking region of the mouse activin ßa subunit gene. The nucleotide sequence determination of the 5′‐flanking region of the gene and the comparison of that with the reported mouse cDNA structure identified the putative 5′ regulatory region, a novel first exon and a part of the first intron of the gene within this region. The putative 5′ regulatory region of the mouse activin ßa subunit gene directed the expression of CAT gene in transfected HT1080 cells. Successive deletions of this region demonstrated a 400‐bp region that exerts a strong positive effect on promoter activity of the mouse activin ßa subunit gene.
Involvement of a third histidine in the ferrous active site of isopenicillin N synthase of Cephalosporium acremonium repudiated by recombinant double histidine mutants
Authors: Tan D. S. H. , Ang S. G. , Sim T. S. 
Published: July 2007

AbstractSite‐directed mutagenesis studies have shown that the isopenicillin N synthase of Cephalosporium acremonium (cIPNS) requires two essential histidine residues (H216, H272) for activity. The determination of iron bound to the wildtype cIPNS and its absence in the mutants lacking histidine at positions 216 and 272 clearly supports the essential role these two histidines play in iron binding. However, nuclear magnetic resonance (NMR) studies have indicated that there could be three histidine residues that possibly coordinate the essential iron at the active site. To search for a presumed third histidine ligand, mutant cIPNS genes containing mutations at two histidine codons were created by in vitro cloning of fragments from the expression vectors bearing the respective cIPNS genes each with a single histidine mutation at positions H49, H64, H116, H126 and H137. All ten possible double histidine mutant cIPNS constructs were subsequently expressed in Escherichia coli. If a third histidine had a participatory role in the iron active centre of cIPNS, then one of the constructed double histidine mutants would have lost its enzymatic activity. However, analysis of the cIPNS activities of these recombinant double histidine mutants indicated that none of them was totally inactivated. Thus, the involvement of a third histidine can be repudiated.
In vitro processing of cucumber chloroplast tRNALeu (CAA) precursor in a pea chloroplast soluble extract
Authors: Hande Shailaja , Jayabaskaran C. 
Published: July 2007

AbstractTo study the sequential steps in the processing pathway of the chloroplast monocistronic intronless tRNA precursors, we examined cucumber chloroplast tRNALLeu(CAA) processing in a cucumber or pea chloroplast soluble extract. The tRNALeu(CAA) precursor synthesized from SP6 RNA polymerase‐directed transcription system, was used as a substrate. Incubation of the tRNA precursor with the pea extract resulted in processing of tRNALeu(CAA) via 5′‐ and 3′‐endonucleolytic cleavages followed by final trimming of extra 3′nucleotides by 3′ exonuclease(s). No preferred order for endonucleolytic cleavages has been observed during the in vitro tRNALLeu processing and the simultaneous occurrence of the intermediates consisting of leader + tRNALeu and tRNALeu + trailer, indicate that either 5′‐ or 3′‐ endonucleolitic cleavage can occur as the first step in vitro.
Characterization of extracellular menadion‐catalyzed H2O2 production by NTH/3T3 cells
Authors: Yamashoji S. 
Published: July 2007

AbstractThe extracellular menadione‐catalyzed H202 production by NIH/3T3 cells was expected to depend on plasma membrane‐bound NAD(P)H:quinone oxidoreductase. This enzyme was estimated to be a flavoprotein with the molecular mass of 70 KDa. Km values of plasma membrane‐bound NAD(P)H:quinone oxidoreductase producing H20 2 were 60 μM for NADH and 150 μM for NADPH. Ca2+ ionophore A23187 controlled menadione‐catalyzed H2O2 production by the cells in time‐ and concentration‐dependent manner.