bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum Phase Coherence in Mesoscopic Transport Devices with Two-Particle Interaction
Authors: Wang Zhimei , Guo Xiaofang , Xue Haibin , Xue Naitao , Liang J.-Q. 
Published: August 2015

AbstractIn this paper we demonstrate a new type of quantum phase coherence (QPC), which is generated by the two-body interaction. This conclusion is based on quantum master equation analysis for the full counting statistics of electron transport through two parallel quantum-dots with antiparallel magnetic fluxes in order to eliminate the Aharonov-Bohm interference of either single-particle or non-interacting two-particle wave functions. The interacting two-particle QPC is realized by the flux-dependent oscillation of the zero-frequency cumulants including the shot noise and skewness with a characteristic period. The accurately quantized peaks of cumulant spectrum may have technical applications to probe the two-body Coulomb interaction.
A Validated Phenotyping Algorithm for Genetic Association Studies in Age-related Macular Degeneration
Authors: Simonett Joseph M. , Sohrab Mahsa A. , Pacheco Jennifer , Armstrong Loren L. , Rzhetskaya Margarita , Smith Maureen , Hayes M. Geoffrey , Fawzi Amani A. 
Published: August 2015

AbstractAge-related macular degeneration (AMD), a multifactorial, neurodegenerative disease, is a leading cause of vision loss. With the rapid advancement of DNA sequencing technologies, many AMD-associated genetic polymorphisms have been identified. Currently, the most time consuming steps of these studies are patient recruitment and phenotyping. In this study, we describe the development of an automated algorithm to identify neovascular (wet) AMD, non-neovascular (dry) AMD and control subjects using electronic medical record (EMR)-based criteria. Positive predictive value (91.7%) and negative predictive value (97.5%) were calculated using expert chart review as the gold standard to assess algorithm performance. We applied the algorithm to an EMR-linked DNA bio-repository to study previously identified AMD-associated single nucleotide polymorphisms (SNPs), using case/control status determined by the algorithm. Risk alleles of three SNPs, rs1061170 (CFH), rs1410996 (CFH) and rs10490924 (ARMS2) were found to be significantly associated with the AMD case/control status as defined by the algorithm. With the rapid growth of EMR-linked DNA biorepositories, patient selection algorithms can greatly increase the efficiency of genetic association study. We have found that stepwise validation of such an algorithm can result in reliable cohort selection and, when coupled within an EMR-linked DNA biorepository, replicates previously published AMD-associated SNPs.
Paclitaxel-induced lung injury and its amelioration by parecoxib sodium
Authors: Liu Wen-jie , Zhong Zhong-jian , Cao Long-hui , Li Hui-ting , Zhang Tian-hua , Lin Wen-qian 
Published: August 2015

AbstractTo investigate the mechanism of paclitaxel-induced lung injury and its amelioration by parecoxib sodium. In this study, rats were randomly divided into: the control group (Con); the paclitaxel chemotherapy group (Pac); the paclitaxel+ parecoxib sodium intervention group (Pac + Pare); and the parecoxib sodium group (Pare). We observed changes in alveolar ventilation function, alveolar-capillary membrane permeability, lung tissue pathology and measured the levels of inflammatory cytokines and cyclooxygenase-2 (Cox-2) in lung tissue, the expression of tight junction proteins (Zo-1 and Claudin-4). Compared with the Con group, the lung tissue of the Pac group showed significantly increased expression of Cox-2 protein (p < 0.01), significant lung tissue inflammatory changes, significantly increased expression of inflammatory cytokines, decreased expression of Zo-1 and Claudin-4 proteins (p < 0.01), increased alveolar-capillary membrane permeability (p < 0.01) and reduced ventilation function (p < 0.01). Notably, in Pac + Pare group, intraperitoneal injection of parecoxib sodium led to decreased Cox-2 and ICAM-1 levels and reduced inflammatory responses, the recovered expression of Zo-1 and Claudin-4, reduced level of indicators reflecting the high permeability state and close-to-normal levels of ventilation function. Intervention by the Cox-2-specific inhibitor parecoxib sodium can block this damage.
Human phosphodiesterase 4A: characterization of full-length and truncated enzymes expressed in COS cells
Authors: OWENS Raymond J. , CATTERALL Cath , BATTY Dawn , JAPPY John , RUSSELL Annette , SMITH Bryan , O'CONNELL Jimi , PERRY Martin J. 
Published: August 2015

The type 4 phosphodiesterase (PDE) family comprises four enzymes (4A, 4B, 4C and 4D) that are characterized by their specificity for cAMP and selective inhibition by the antidepressant drug rolipram {4-[3-(cyclopentoxyl)-4-methoxyphenyl]2-pyrrolidone}. In common with other PDEs, they consist of a central conserved domain associated with catalytic activity in addition to two N-terminal upstream conserved regions (UCR1 and UCR2) that are unique to the type 4 enzymes. We have isolated a 2 kb cDNA encoding a full-length type 4A PDE {HS PDE4A4B [Bolger, Michaeli, Martins, St.John, Steiner, Rodgers, Riggs, Wigler and Ferguson (1993) Mol. Cell Biol. 13, 6558–6571]} from a human frontal cortex cDNA library. Northern blot analysis showed that the major PDE4A mRNA of 4.5 kb was widely distributed in different human tissues. The recombinant PDE4A expressed in COS cells had a molecular mass of approx. 117 kDa as revealed by SDS/PAGE/Western blotting with a PDE4A-specific antibody and was specific for cAMP with a Km of 4.8 μM. The enzyme activity was potently inhibited by R-rolipram (IC50 204 nM) and showed a 2.7-fold stereoselectivity over the S enantiomer. Analysis of the kinetics of inhibition indicated that R-rolipram did not behave as a simple competitive inhibitor. Dixon replots suggested that there was more than one mode of interaction consistent with the detection in the enzyme of a high-affinity binding site for R-rolipram with a Kd of 2.3 nM. Truncation of the PDE4A enzyme by deletion mutagenesis showed that neither of the UCRs was required for catalytic activity and identified an approx. 71 kDa core enzyme with a Km for cAMP of 3.3 μM. In contrast with the full-length PDE4A, R-rolipram behaved as a simple competitive inhibitor of this form of the enzyme with decreased potency (IC50 1022 nM) and no stereoselectivity. In addition, no high-affinity rolipram-binding site was detected in the truncated enzyme, indicating that this interaction involves sequences upstream of the catalytic domain of the enzyme.
Incremental Ca2+ mobilization by inositol trisphosphate receptors is unlikely to be mediated by their desensitization or regulation by luminal or cytosolic Ca2+
Authors: BEECROFT Mike D. , TAYLOR Colin W. 
Published: August 2015

The kinetics of Ins(1,4,5)P3 (InsP3)-stimulated Ca2+ release from intracellular stores are unusual in that submaximal concentrations of InsP3 rapidly release only a fraction of the InsP3-sensitive Ca2+ stores. By measuring unidirectional 45Ca2+ efflux from permeabilized rat hepatocytes, we demonstrate that such quantal responses to InsP3 occur at all temperatures between 2 and 37 °C, but at much lower rates at the lower temperatures. Preincubation with submaximal concentrations of InsP3, which themselves evoked quantal Ca2+ release, had no effect on the sensitivity of the stores to further additions of InsP3. The final Ca2+ content of the stores was the same whether they were stimulated with two submaximal doses of InsP3 or a single addition of the sum of these doses. Such incremental responses and the persistence of quantal behaviour at 2 °C indicate that InsP3-evoked receptor inactivation is unlikely to be the cause of quantal Ca2+ mobilization. Reducing the Ca2+ content of the intracellular stores by up to 45% did not affect their sensitivity to InsP3, but substantially reduced the time taken for each submaximal InsP3 concentration to exert its full effect. These results suggest that neither luminal nor cytosolic Ca2+ regulation of InsP3 receptors are the determinants of quantal behaviour. Our results are not therefore consistent with incremental responses to InsP3 depending on mechanisms involving attenuation of InsP3 receptor function by cytosolic or luminal Ca2+ or by InsP3 binding itself. We conclude that incremental activation of Ca2+ release results from all-or-nothing emptying of stores with heterogeneous sensitivities to InsP3. These characteristics allow rapid graded recruitment of InsP3-sensitive Ca2+ stores as the cytosolic InsP3 concentration increases.
Phosphotyrosine phosphatase activity associated with c-Src in large multimeric complexes isolated from adrenal medullary chromaffin cells
Authors: VAN HOEK Monique L. , ALLEN Colleen S. , PARSONS Sarah J. 
Published: August 2015

Chromaffin cells, which secrete catecholamines in response to acetylcholine, express high levels of the Src-family tyrosine kinases. These kinases contain protein–protein interaction domains which bind signal transduction proteins that participate in a variety of cellular processes. To determine if signalling proteins bind c-Src in chromaffin cells, we examined c-Src immunocomplexes for co-precipitating proteins. We discovered a phosphotyrosine phosphatase (PTPase; EC 3.1.3.48) activity which associates with specific subcellular pools of c-Src in vivo and which preferentially binds the SH2 (Src homology 2) domain of c-Src in vitro. Known PTPases were not identified by blotting of c-Src immunocomplexes with a panel of anti-PTPase antibodies, suggesting that the PTPase may be a novel family member. The c-Src–PTPase complex is enriched in the plasma membrane fraction and exists in several large complexes, as revealed by gel-filtration analysis. This PTPase activity is altered rapidly following stimulation by secretagogues, decreasing within 30 s and returning to basal levels by 60 s of stimulation. Both the subcellular localization and rapid activity changes suggest that the c-Src-associated PTPase may function in early signalling events emanating from the nicotinic acetylcholine receptor. In support of this is the co-precipitation of a PTPase activity with the nicotinic acetylcholine receptor and co-chromatography of this receptor with one of the c-Src–PTPase complexes.
G-protein βγ subunits antagonize protein kinase C-dependent phosphorylation and inhibition of phospholipase C-β1
Authors: LITOSCH Irene 
Published: August 2015

Protein kinase C (PKC) isoforms phosphorylated phospholipase C-β1 (PLC-β1) in vitro as follows: PKCα ≫ PKCϵ; not PKCζ. PLC-β3 was not phosphorylated by PKCα. G-protein βγ subunits inhibited the PKCα phosphorylation of PLC-β1 in a concentration-dependent manner. Half-maximal inhibition occurred with 500 nM βγ. G-protein βγ subunits also antagonized the PKCα-mediated inhibition of PLC-β1 enzymic activity. PKCα, in turn, inhibited the stimulation of PLC-β1 activity by βγ. There was little effect of PKCα on the stimulation of PLC-β1 by αq/11–guanosine 5′[γ-thio]triphosphate (GTP[S]). These findings demonstrate that G protein βγ subunits antagonize PKCα regulation of PLC-β1. Thus βγ subunits might have a role in modulating the negative feedback regulation of this signalling system by PKC.
Novel bradykinin signalling events in PC-12 cells: stimulation of the cAMP pathway leads to cAMP-mediated translocation of protein kinase Cε
Authors: GRANESS Angela , ADOMEIT Antje , LUDWIG Beate , MÜLLER Wolf-Dieter , KAUFMANN Roland , LIEBMANN Claus 
Published: August 2015

In the rat pheochromocytoma cell line PC-12, bradykinin (BK) stimulated phosphatidylinositol hydrolysis by 4–5-fold and, additionally, intracellular cAMP accumulation by approx. 1.6-fold. EC50 values for BK were 3 nM and 2 nM respectively. The BK-induced increase in cAMP accumulation was paralleled by a 1.6-fold increase in protein kinase A (PKA) activity. The time course of BK-stimulated inositol phosphate formation was rapid (t1/2 &lt; 1 min), whereas the BK-induced cAMP accumulation was lagging (t1/2 approx. 6 min). The effect of BK on the cAMP pathway was independent of pertussis toxin, excluding an indirect stimulation of adenylate cyclase via βγ-complexes from Gi or Go proteins. Two different protein kinase C (PKC) inhibitors, bisindolylmaleimide and Ro 31-820, failed to prevent BK-induced cAMP accumulation, and exclude PKC as mediator of BK action on adenylate cyclase. In contrast, the stimulatory effect of BK on cAMP accumulation was completely abolished by two calmodulin antagonists, chlorpromazine and ophiobolin, suggesting an indirect, Ca2+/calmodulin-mediated effect of BK on the cAMP pathway. In addition, exposure of PC-12 cells to BK resulted in a translocation of the PKC isoforms α, δ, ϵ and ζ displaying different kinetics. The BK-induced translocations of the PKCs α and δ were rapid and biphasic, whereas the PKCs ϵ and ζ revealed a slower and slightly transient translocation in response to BK. The BK-elicited translocation of PKCϵ, but not that of the PKCs α, δ and ζ, was prevented by two different inhibitors of adenylate cyclase, 2′,5′-dideoxyadenosine and MDL-12,330A, as well as the PKA inhibitor adenosine 3′:5′-monophosphothioate. These findings suggest that the BK-induced translocation of novel (n)PKCϵ is mediated via the cAMP pathway. Since nPKCϵ appears to regulate neurite outgrowth in PC-12 cells [Hundke, McMahon, Dadgar and Messing (1995) J. Biol. Chem. 270, 30134–30140] our results provide evidence for a novel signalling mechanism that might be involved in BK-induced neuronal differentiation of PC-12 cells.
3,5,3′-Tri-iodo-l-thyronine acutely regulates a protein kinase C-sensitive, Ca2+-independent, branch of the hepatic α1-adrenoreceptor signalling pathway
Authors: DAZA Francisco J. , PARRILLA Roberto , MARTÍN-REQUERO Angeles 
Published: August 2015

This work aimed to investigate the acute effect of the thyroid hormone 3,5,3´-tri-iodo-l-thyronine (T3) in regulating the hepatic metabolism either directly or by controlling the responsiveness to Ca2+-mobilizing agonists. We did not detect any acute metabolic effect of T3 either in perfused liver or in isolated liver cells. However, T3 exerted a powerful inhibitory effect on the α1-adrenoreceptor-mediated responses. The promptness of this T3 effect rules out that it was the result of rate changes in gene(s) transcription. T3 inhibited the α1-adrenoreceptor-mediated sustained stimulation of respiration and release of Ca2+ and H+, but not the glycogenolytic or gluconeogenic responses, in perfused liver. In isolated liver cells, T3 enhanced the α1-agonist-induced increase in cytosolic free Ca2+ and impeded the intracellular alkalinization. Since T3 also prevented the α1-adrenoreceptor-mediated activation of protein kinase C, its effects on pH seem to be the result of a lack of activation of the Na+/H+ exchanger. The failure of T3 to prevent the α1-adrenergic stimulation of gluconeogenesis despite the inhibition of protein kinase C activation indicates that the elevation of cytosolic free Ca2+ is a sufficient signal to elicit that response. T3 also impaired some of the angiotensin-II-mediated responses, but did not alter the effects of PMA on hepatic metabolism, indicating, therefore, that some postreceptor event is the target for T3 actions. The differential effect of T3 in enhancing the α1-adrenoreceptor-mediated increase in cytosolic free Ca2+ and preventing the activation of protein kinase C, provides a unique tool for further investigating the role of each branch of the signalling pathway in controlling the hepatic functions. Moreover, the low effective concentrations of T3 (⩽ 10 nM) in perturbing the α1-adrenoreceptor-mediated response suggests its physiological significance.
A mitochondrial membrane protein is required for translocation of phosphatidylserine from mitochondria-associated membranes to mitochondria
Authors: SHIAO Young-Ji , BALCERZAK Bénédicte , VANCE Jean E. 
Published: August 2015

The mechanism of import of phosphatidylserine (PtdSer) into mitochondria was investigated using a reconstituted system of isolated organelles in vitroin which PtdSer was translocated from donor membranes to mitochondria and was decarboxylated therein. Neither phosphatidylcholine nor phosphatidylethanolamine (PtdEtn) was translocated under the same conditions. Transfer of PtdSer from its site of synthesis on the endoplasmic reticulum and mitochondria-associated membranes [J. E. Vance (1990) J. Biol. Chem. 265, 7248–7256] to its site of decarboxylation on mitochondrial inner membranes is predicted to be mediated by membrane contact. A mitochondrial membrane protein appears to be involved in the translocation event since proteolysis of proteins exposed on the mitochondrial surface potently inhibited PtdSer transfer, whereas proteolysis of surface proteins of mitochondria-associated membranes did not impair the transfer. The nature of the membranes that donate PtdSer to mitochondria in vitrois not crucial since PtdSer of mitochondria-associated membranes, endoplasmic reticulum and microsomes was decarboxylated to PtdEtn with approximately equal efficiency. The translocation of PtdSer to mitochondria was stimulated by magnesium and calcium ions and was inhibited by incubation of mitochondria with sulphydryl group-modifying reagents. Reconstitution of PtdSer translocation/decarboxylation using digitonin-solubilized mitochondria and PtdSer-donor membranes suggested that the putative PtdSer-translocation protein is primarily localized to contract sites between mitochondrial inner and outer membranes. These studies provide evidence for the involvement of a mitochondrial membrane protein in the import of newly-synthesized PtdSer into mitochondria.
Phospholipase C-δ1 and oxytocin receptor signalling: evidence of its role as an effector
Authors: PARK Eu-Suk , WON Jong Hyun , HAN Kee Jung , SUH Pann-Ghill , RYU Sung Ho , LEE Hee Sung , YUN Hye-Young , KWON Nyoun Soo , BAEK Kwang Jin 
Published: August 2015

Although the oxytocin receptor modulates intracellular Ca2+ ion levels in myometrium, the identities of signal molecules have not been clearly clarified. Our previous studies on oxytocin receptor signalling demonstrated that 80 kDa Ghα is a signal mediator [Baek, Kwon, Lee, Kim, Muralidhar and Im (1996) Biochem. J. 315, 739–744]. To elucidate the effector in the oxytocin receptor signalling pathway, we evaluated the oxytocin-mediated activation of phospholipase C (PLC) by using solubilized membranes from human myometrium and a three-component preparation containing the oxytocin receptor–Ghα–PLC-δ1 complex. PLC-δ1 activity in the three-component preparation, as well as PLC activity in solubilized membranes, was increased by oxytocin in the presence of Ca2+ and activated Ghα (GTP-bound Ghα). Furthermore the stimulated PLC-δ1 activity resulting from activation of Ghα via the oxytocin receptor was significantly attenuated by the selective oxytocin antagonist desGly-NH2d(CH2)5[Tyr(Me)2,Thr4]ornithine vasotocin or GDP. Consistent with these observations, co-immunoprecipitation and co-immunoadsorption of PLC-δ1 in the three-component preparation by anti-Gh7α antibody resulted in the PLC-δ1 being tightly coupled to activated Ghα on stimulation of the oxytocin receptor. These results indicate that PLC-δ1 is the effector for Ghα-mediated oxytocin receptor signalling.
The dhnA gene of Escherichia coli encodes a Class I fructose bisphosphate aldolase
Authors: THOMSON Graeme J. , HOWLETT Geoffrey J. , ASHCROFT Alison E. , BERRY Alan 
Published: August 2015

The gene encoding the Escherichia coli Class I fructose-1,6-bisphosphate aldolase (FBP aldolase) has been cloned and the protein overproduced in high amounts. This gene sequence has previously been identified as encoding an E. coli dehydrin in the GenBank™ database [gene dhnA; entry code U73760; Close and Choi (1996) Submission to GenBank™]. However, the purified protein overproduced from the dhnA gene shares all its properties with those known for the E. coli Class I FBP aldolase. The protein is an 8–10-mer with a native molecular mass of approx. 340 kDa, each subunit consisting of 349 amino acids. The Class I enzyme shows low sequence identity with other known FBP aldolases, both Class I and Class II (in the order of 20%), which may be reflected by some novel properties of this FBP aldolase. The active-site peptide has been isolated and the Schiff-base-forming lysine residue (Lys236) has been identified by a combination of site-directed mutagenesis, kinetics and electrospray-ionization MS. A second lysine residue (Lys238) has been implicated in substrate binding. The cloning of this gene and the high levels of overexpression obtained will facilitate future structure–function studies.
S-Nitrosoglutathione is a substrate for rat alcohol dehydrogenase class III isoenzyme
Authors: JENSEN David E. , BELKA George K. , BOIS Garrett C. Du 
Published: August 2015

An enzyme isolated from rat liver cytosol (native molecular mass 78.3 kDa; polypeptide molecular mass 42.5 kDa) is capable of catalysing the NADH/NADPH-dependent degradation of S-nitrosoglutathione (GSNO). The activity utilizes 1 mol of coenzyme per mol of GSNO processed. The isolated enzyme has, as well, several characteristics that are unique to alcohol dehydrogenase (ADH) class III isoenzyme: it is capable of catalysing the NAD+-dependent oxidations of octanol (insensitive to inhibition by 4-methylpyrazole), methylcrotyl alcohol (stimulated by added pentanoate) and 12-hydroxydodecanoic acid, and also the NADH/NADPH-dependent reduction of octanal. Methanol and ethanol oxidation activity is minimal. The enzyme has formaldehyde dehydrogenase activity in that it is capable of catalysing the NAD+/NADP+-dependent oxidation of S-hydroxymethylglutathione. Treatment with the arginine-specific reagent phenylglyoxal prevents the pentanoate stimulation of methylcrotyl alcohol oxidation and markedly diminishes the enzymic activity towards octanol, 12-hydroxydodecanoic acid and S-hydroxymethylglutathione; the capacity to catalyse GSNO degradation is also checked. Additionally, limited peptide sequencing indicates 100% correspondence with known ADH class III isoenzyme sequences. Kinetic studies demonstrate that GSNO is an exceptionally active substrate for this enzyme. S-Nitroso-N-acetylpenicillamine and S-nitrosated human serum albumin are not substrates; the activity towards S-nitrosated glutathione mono- and di-ethyl esters is minimal. Product analysis suggests that glutathione sulphinamide is the major stable product of enzymic GSNO processing, with minor yields of GSSG and NH3; GSH, hydroxylamine, nitrite, nitrate and nitric oxide accumulations are minimal. Inclusion of GSH in the reaction mix decreases the yield of the supposed glutathione sulphinamide in favor of GSSG and hydroxylamine.