julilili42/papers huggingface dataset:
MDR1 gene polymorphisms and disposition of the P‐glycoprotein substrate fexofenadine
2002-05-01

Aims The C3435T polymorphism in the human MDR1 gene is associated with lower intestinal P‐glycoprotein expression, reduced protein function in peripheral blood cells and higher plasma concentrations of the P‐glycoprotein substrate digoxin. Using fexofenadine, a known P‐glycoprotein substrate, the hypothesis was tested whether this polymorphism also affects the disposition of other drugs in humans. Methods Ten Caucasian subjects homozygous for the wild‐type allele at position 3435 (CC) and 10 individuals homozygous for T at position 3435 participated in this study. A single oral dose of 180 mg fexofenadine HCl was administered. Plasma and urine concentrations of fexofenadine were measured up to 72 h using a sensitive LC/MS method. In addition, P‐glycoprotein function was assessed using efflux of the P‐glycoprotein substrate rhodamine 123 from CD56 + cells. Results Fexofenadine plasma concentrations varied considerably among the study population. However, fexofenadine disposition was not significantly different between the CC and TT groups (e.g. AUC(0,∞) CC vs TT: 3567.1±1535.5 vs 3910.1±1894.8 ng ml −1 h, NS; 95% CI on the difference −1364.9, 2050.9). In contrast, P‐glycoprotein function was significantly decreased in CD56 + cells of the TT compared with the CC group (rhodamine fluorescence CC vs TT: 45.6±7.2% vs 61.1±12.3%, P &lt;0.05; 95% CI on the difference 5.6, 25.5). Conclusions In spite of MDR1 genotype‐dependent differences in P‐glycoprotein function in peripheral blood cells, there was no association of the C3435T polymorphism with the disposition of the P‐glycoprotein substrate fexofenadine in this German Caucasian study population. These data indicate that other mechanisms including uptake transporter function are likely to play a role in fexofenadine disposition.
A Transmembrane Tight Junction Protein Selectively Expressed on Endothelial Cells and Platelets
2002-05-01

Searching for cell surface proteins expressed at interendothelial cell contacts, we have raised monoclonal antibodies against intact mouse endothelial cells. We obtained two monoclonal antibodies, 1G8 and 4C10, that stain endothelial cell contacts and recognize a protein of 55 kDa. Purification and identification by mass spectrometry of this protein revealed that it contains two extracellular Ig domains, reminiscent of the JAM family, but a much longer 120-amino acid cytoplasmic domain. The antigen is exclusively expressed on endothelial cells of various organs as was analyzed by immunohistochemistry. Immunogold labeling of ultrathin sections of brain as well as skeletal muscle revealed that the antigen strictly colocalizes in capillaries with the tight junction markers occludin, claudin-5, and ZO-1. Upon transfection into MDCK cells, the antigen was restricted to the most apical tip of the lateral cell surface, where it colocalized with ZO-1 but not with beta-catenin. In contrast to JAM-1, however, the 1G8 antigen does not associate with the PDZ domain proteins ZO-1, AF-6, or ASIP/PAR-3, despite the presence of a PDZ-binding motif. The 1G8 antigen was not detected on peripheral blood mouse leukocytes, whereas similar to JAM-1 it was strongly expressed on platelets and megakaryocytes. The 1G8 antigen supports homophilic interactions on transfected Chinese hamster ovary cells. Based on the similarity to the JAM molecules, it is plausible that the 1G8 antigen might be involved in interendothelial cell adhesion.
Identification of CD70-mediated apoptosis of immune effector cells as a novel immune escape pathway of human glioblastoma.
2002-05-01

Interactions of CD70, a tumor necrosis factor-related cell surface ligand and its receptor, CD27, are thought to play an important role for T-, B-, and natural killer-cell activation. However, ligation of CD27 can also induce apoptosis. Human glioblastoma is paradigmatic for cancer-associated immunosuppression. We identified CD70 as a radioinducible gene in U87 MG glioma cells. A screening of a panel of human glioma cell lines revealed that 11 of 12 cell lines expressed CD70 mRNA and protein. Two human neuroblastoma cell lines did not express CD70. CD70 mRNA expression was enhanced by irradiation in 8 of 12 glioma cell lines in a p53-independent manner. No alteration in CD70 expression was observed after glioma cell exposure to cytotoxic drugs such as lomustine. CD70 protein was also detected by immunocytochemistry in 5 of 12 glioblastomas and 3 of 4 anaplastic astrocytomas in vivo. CD27 expression was not detected in any glioma cell line, and there was no evidence for autocrine or backward signaling of the CD70 system in human glioma cells. Unexpectedly, CD70 expressed on glioma cells did not increase the immunogenicity of glioma cells in vitro. In contrast, CD70-positive glioma cells induced apoptosis in peripheral blood mononuclear cells (PBMCs) in a CD70-dependent manner. Neutralization of CD70 expressed on glioma cells prevented apoptosis and enhanced the release of tumor necrosis factor-alpha in cocultures of glioma cells and PBMCs. The effects of CD70-expressing glioma cells on PBMCs were mimicked by agonistic CD27 antibodies. Conversely, the shedding of CD27 by PBMCs was identified as a possible escape mechanism from glioma cell-induced CD70-dependent apoptosis. Thus, induction of B-cell and T-cell apoptosis via interactions of CD70 expressed on glioma cells and CD27 expressed on B and T cells may be a novel way for the immune escape of malignant gliomas.
Biosynthetic Gene Cluster of Simocyclinone, a Natural Multihybrid Antibiotic
2002-05-01

ABSTRACT The entire simocyclinone biosynthetic cluster ( sim gene cluster) from the producer Streptomyces antibioticus Tü6040 was identified on six overlapping cosmids (1N1, 5J10, 2L16, 2P6, 4G22, and 1K3). In total, 80.7 kb of DNA from these cosmids was sequenced, and the analysis revealed 49 complete open reading frames (ORFs). These ORFs include genes responsible for the formation and attachment of four different moieties originating from at least three different pools of primary metabolites. Also in the sim gene cluster, four ORFs were detected that resemble putative regulatory and export functions. Based on the putative function of the gene products, a model for simocyclinone D8 biosynthesis was proposed. Biosynthetic mutants were generated by insertional gene inactivation experiments, and culture extracts of these mutants were analyzed by high-performance liquid chromatography. Production of simocyclinone D8 was clearly detectable in the wild-type strain but was not detectable in the mutant strains. This indicated that indeed the sim gene cluster had been cloned.
Studies on the Anti-Inflammatory Activity of Phytopharmaceuticals Prepared from Arnica Flowers1
2002-05-01

Phytopharmaceuticals prepared from flowerheads of Arnica montana of Spanish origin and of the new type "Arbo", which can be easily and economically cultivated, were studied for their capability to impair activation of the transcription factors NF-kappa B and NF-AT. Both proteins are responsible for the transcription of genes encoding various inflammatory mediators. Additionally, their influence on the release of the cytokines IL-1 and TNF-alpha were examined. The inhibitory activities correlate with their quantitative and qualitative content of sesquiterpene lactones (Sls). Moreover, it was shown that the inhibitory potency of 11 alpha,13-dihydrohelenalin derivatives being the main Sls in the Spanish flowers depend on their esterfication. Compounds with unsaturated acyl moieties, such as methacrylate and tiglinate, exhibited a stronger activity in the NF-kappa B EMSA as well as in the croton oil ear test in mice than the acetate derivative.
LeCPK1, a Calcium-Dependent Protein Kinase from Tomato. Plasma Membrane Targeting and Biochemical Characterization
2002-05-01

Abstract The cDNA of LeCPK1, a calcium-dependent protein kinase, was cloned from tomato (Lycopersicon esculentum Mill.). LeCPK1 was expressed in Escherichia coli and purified from bacterial extracts. The recombinant protein was shown to be a functional protein kinase using a synthetic peptide as the substrate (syntide-2,K m = 85 μm). Autophosphorylation of LeCPK1 was observed on threonine and serine residues, one of which was identified as serine-439. Kinase activity was shown to be Ca2+ dependent and required the C-terminal, calmodulin-like domain of LeCPK1. Two classes of high- and low-affinity Ca2+-binding sites were observed, exhibiting dissociation constants of 0.6 and 55 μm, respectively. LeCPK1 was found to phosphorylate the regulatory C-terminal domain of the plasma membrane H+-ATPase in vitro. A potential role in the regulation of proton pump activity is corroborated by the apparent colocalization of the plasma membrane H+-ATPase and LeCPK1 in vivo. Upon transient expression in suspension-cultured cells, a C-terminal fusion of LeCPK1 with the green fluorescent protein was targeted to the plasma membrane. Myristoylation of theLeCPK1 N terminus was found to be required for plasma membrane targeting.
Conjugated Macrocycles as Active Materials in Nonlinear Optical Processes: Optical Limiting Effect with Phthalocyanines and Related Compounds
2002-05-01

Abstract An overview of the optical limiting (OL) processes in phthalocyanines and related compounds is presented, particularly a description of the synthesis and relevant optical properties of a series of axially substituted indium(III), titanium(IV), phthalo‐ and naphthalocyanines, and octaarylporphyrazines. Several techniques, such as transient absorption, Z‐scan, and degenerate four‐wave mixing, were used to assess the optical properties and OL performance of the investigated compounds. The versatility of the methods of organic synthesis leads to the achievement of effective systems in terms of OL performance through the appropriate combination and modulation of several structural components. The chemistry of the macrocycles here considered allows the variation of the different chemical features, such as the degree of electronic conjugation of the macrocycle and the nature of the ring substituents, the central atom, and the ligands attached to the central atom. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 129–148, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10024
Cellular electrophysiology of atrial fibrillation
2002-05-01

Time for primary review 23 days. Atrial fibrillation (AF) is presently the most common cardiac arrhythmia in clinical practice. Its treatment is inadequate. Maintenance of normal sinus rhythm (SR) is obviously the optimal approach, but is difficult to achieve without drugs that have the potential to cause ventricular proarrhythmia and increase mortality. Non-pharmacological therapy is attractive, but to date has not reached the same level of efficacy as in the treatment of arrhythmias other than AF. In order to improve therapeutic approaches, it is important to understand the detailed pathophysiology of the arrhythmia. A key component to the pathophysiology of any cardiac arrhythmia is the cellular milieu in which it occurs. Changes in ion transport processes, including pumps, channels and exchangers, are central to alterations in action potential properties that govern the occurrence of arrhythmias like AF. Action potential duration (APD) determines the refractory period and is therefore a key determinant of the likelihood of reentry. Maximum Na+-current ( I Na) governs phase 0 upstroke velocity, determining conduction velocity (CV) and contributing to the likelihood of reentry. Delayed and early afterdepolarizations produce abnormal activity that can in themselves produce tachyarrhythmias and can trigger reentrant arrhythmia. This paper reviews these aspects of the cellular electrophysiology of AF, attempting to summarize what is known, what remains to be explored and what this information can teach us about why AF occurs and how to treat it. The identification of the molecular structure of many ion channels involved in cardiac excitability and their functional correlation with native ionic currents have made it possible to study the effects of pathophysiological conditions, like AF, at different levels from genes to ionic currents. The different steps underlying the expression of an ion channel are depicted in Fig. 1 and have recently been reviewed by Roden and ... * Corresponding author. Tel.: +49-7071-298-3196; fax: +49-7071-294-121 ralph.bosch{at}uni-tuebingen.de
Cytotoxic Action of Acetyl-11-keto-β-Boswellic Acid (AKBA) on Meningioma Cells
2002-05-01

Acetyl-11-keto-beta-boswellic acid (AKBA) is a naturally occurring pentacyclic triterpene isolated from the gum resin exudate of the tree Boswellia serrata (frankincense). Because pentacyclic triterpenes have antiproliferative and cytotoxic effects against different tumor types, we investigated whether AKBA would act in a similar fashion on primary human meningioma cell cultures. Primary cell cultures were established from surgically removed meningioma specimens. The number of viable cells in the absence/presence of AKBA was determined by the non-radioactive cell proliferation assay. The activation status of the proliferative cell marker, extracellular signal-regulated kinase-1 and -2 (Erk-1 and Erk-2) was determined by immunoblotting with the antibody that recognizes the activated form of these proteins. Treatment of meningioma cells by AKBA revealed a potent cytotoxic activity with half-maximal inhibitory concentrations in the range of 2 - 8 microM. At low micromolar concentrations, AKBA rapidly and potently inhibited the phosphorylation of Erk-1/2 and impaired the motility of meningioma cells stimulated with platelet-derived growth factor BB. The cytotoxic action of AKBA on meningioma cells may be mediated, at least in part, by the inhibition of the Erk signal transduction pathway. Because of the central role the Erk pathway plays in signal transduction and tumorigenesis, further investigation into the potential clinical use for AKBA and related boswellic acids is warranted.
Storekeeper defines a new class of plant‐specific DNA‐binding proteins and is a putative regulator of patatin expression
2002-05-01

Summary The expression of class I patatin genes is restricted to potato tubers but can be induced in other tissues by exogenous sucrose. Here we show that tuber‐specific and sucrose‐inducible gene expression is reduced in transgenic potato plants by mutations in a conserved 10 base pair motif within the B‐box of the patatin promoter. In a southwestern screen, we have isolated a novel DNA‐binding protein designated Storekeeper (STK) that specifically recognises the B‐box motif in vitro . Gel shift experiments with an STK‐specific antibody suggest that STK is the B‐box binding protein found in tuber nuclei. We propose that STK, the defining member of a new class of DNA binding proteins, regulates patatin expression in potato tubers via the B‐box motif.
Adenylyl Cyclase Rv1264 from Mycobacterium tuberculosis Has an Autoinhibitory N-terminal Domain
2002-05-01

Mycobacterium tuberculosis contains 15 class III adenylyl cyclase genes. The gene Rv1264 is predicted to be composed of two distinct protein modules. The C terminus seems to code for a catalytic domain belonging to a subfamily of adenylyl cyclase isozymes mostly found in Gram-positive bacteria. The expressed protein was shown to function as a homodimeric adenylyl cyclase (1 micromol of cAMP x mg(-1) x min(-1)). In analogy to the structure of the mammalian adenylyl cyclase catalyst, six amino acids were targeted by point mutations and found to be essential for catalysis. The N-terminal region represents a novel protein domain, the occurrence of which is restricted to several adenylyl cyclases present in Gram-positive bacteria. The purified full-length enzyme was 300-fold less active than the catalytic domain alone. Thus, the N-terminal domain appeared to be autoinhibitory. The N-terminal domain contains three prominent polar amino acid residues (Asp(107), Arg(132), and Arg(191)) that are invariant in all seven sequences of this domain currently available. Mutation of Asp(107) to Ala relaxed the inhibition and resulted in a 6-fold increase in activity of the Rv1264 holoenzyme, thus supporting the role of this domain as a potential novel regulator of adenylyl cyclase activity.
Persistent accumulation of cyclooxygenase-1—expressing microglial cells and macrophages and transient upregulation by endothelium in human brain injury
2002-05-01

Object. Secondary damage after central nervous system (CNS) injury is driven in part by oxidative stress and CNS inflammation and is substantially mediated by cyclooxygenases (COXs). To date, the rapidly inducible COX-2 isoform has been primarily linked to inflammatory processes, whereas expression of COX-1 is confined to physiological functions. The authors report the differential localization of COX-1 in human traumatic brain injury (TBI). Methods. Differential cellular COX-1 protein expression profiles were analyzed following TBI in 31 patients and compared with neuropathologically unaltered control brains by using immunohistochemistry. In these patients with TBI, a significant increase of COX-1 protein expression by vessel endothelial and smooth-muscle cells and CD68 + microglia/macrophages was observed to be strictly confined to the lesion. Accumulation of COX-1 + microglia/macrophages in the lesion was already evident 6 hours postinjury, reaching maximal levels after several weeks and remaining elevated at submaximal levels for several months after injury. Furthermore, COX-1 + cell clusters were located in the Virchow—Robin space during the leukocyte infiltration period from Days 4 to 8 after TBI. Double-labeling experiments confirmed coexpression of COX-1 by CD68 + microglia/macrophages. The numbers of COX-1 + vessel endothelial and smooth-muscle cells increased from Day 1, remaining at submaximal levels for months after injury. Conclusions. The prolonged accumulation of COX-1 + microglia/macrophages that were restricted to perilesional areas affected by the acute inflammatory response points to a role of COX-1 in secondary injury. The authors have identified localized, accumulated COX-1 expression as a potential pharmacological target following TBI. Their results challenge the current paradigms of a selective COX-2 role in the postinjury inflammatory response.
Palaeostress analysis of Tertiary post-collisional structures in the Western Pontides, northern Turkey
2002-05-01

Fingerprints of the opening of the Western Black Sea Basin and collision of Pontides and Sakarya Continent along the Intra-Pontide suture can be traced in the area between Cide (Kastamonu) and Kurucaşile (Bartin) in northern Turkey, along the southern coast of the Black Sea. The Western Black Sea Basin is an oceanic basin opened as a back-arc basin of the northward-subducting Intra-Pontide Ocean. Basement units related to this opening are represented by Lower Cretaceous and older units. The first arc magmatism related to this subduction began during Turonian times. Coeval with this magmatism, back-arc extension affected the region and caused development of horst-graben topography. This extensional period resulted in the break-up of continental crust and the oceanic spreading in the Western Black Sea Basin during Late Santonian times. During the Late Campanian–Early Maastrichtian period, the Sakarya Continent and Pontides collided and arc magmatism on the Pontides ended. After this collision, the Western Pontides thickened, imbricated and developed a mainly N-vergent foreland fold and thrust belt character since Late Eocene–Oligocene times. The palaeostress directions calculated from thrust faults of this foreland fold and thrust belt are 4.6°/156.6° for σ1, 6.4°/66.1° for σ2, and 83.2°/261.9° for σ3. The nature of the imbrication indicates that it was a northward prograding foreland system connected to a floor thrust (detachment) fault at the bottom. Field observations on curved slickenfibres support the theory that the thrust faults of this imbricated structure have transformed to oblique thrusts and strike-slip faults over time.
Interaction of LEAFY, AGAMOUS and TERMINAL FLOWER1 in maintaining floral meristem identity in Arabidopsis.
2002-05-01

&lt;b&gt;The &lt;it&gt;Arabidopsis&lt;/it&gt; transcription factor LEAFY acts upstream of homeotic genes such as &lt;it&gt;AGAMOUS&lt;/it&gt; to confer floral identity on meristems that arise after the transition to reproductive development. Compared to the genetic circuitry regulating the establishment of floral meristem identity, little is known about its maintenance. Previous experiments with &lt;it&gt;leafy&lt;/it&gt; heterozygous plants and &lt;it&gt;agamous&lt;/it&gt; mutants grown in conditions that reduce the floral inductive stimulus have shown that both genes are required to prevent reversion of floral to inflorescence meristems. Here, we present evidence that &lt;it&gt;LEAFY&lt;/it&gt; maintains floral meristem identity independently of &lt;it&gt;AGAMOUS&lt;/it&gt;, and that the primary role of LEAFY is either direct repression of shoot identity genes or repression of an intermediate factor that activates shoot identity genes. The latter conclusions were deduced from the phenotypes conferred by a gain-of-function transgene, &lt;it&gt;LEAFY:VP16&lt;/it&gt;, that appears to act as a dominant negative, or antimorphic, allele during maintenance of floral meristem identity. These observations contrast with previous findings that LEAFY acts as a direct activator of floral homeotic genes, supporting the hypothesis that the transcriptional activity of LEAFY is dependent on specific co-regulators.&lt;/b&gt;
Metabotropic glutamate receptors are involved in amygdaloid plasticity
2002-05-01

Abstract The amygdala plays an important role in emotional learning. Synaptic plasticity underlying the acquisition of conditioned fear occurs in the lateral nucleus of the amygdala: long‐term potentiation (LTP) of synapses in the pathway of the conditioned stimulus (CS) has shown to be a neural correlate of this kind of emotional learning. The present study is based on previous results of our laboratory showing an important role of the metabotropic glutamate receptor subtype 5 (mGluR5) in fear conditioning. Here, we explored whether mGlu5 receptors within the lateral nucleus of the amygdala are involved in the plasticity underlying fear conditioning. We used an in vivo approach investigating the acquisition, consolidation and expression of conditioned fear by the fear‐potentiated startle paradigm and by the inhibition of motor activity during CS presentation. Additionally, we used an in vitro approach inducing LTP in the lateral amygdala by patch‐clamp recordings in rat brain slices. Acquisition of conditioned fear, but not consolidation and expression, was blocked by intra‐amygdaloid injections of the specific mGluR5 antagonist 2‐methyl‐6‐(phenylethynyl) pyridine hydrochloride (MPEP) in vivo . Furthermore, induction of amygdaloid LTP but not synaptic transmission was disrupted by MPEP application in vitro . These experiments show for the first time in vivo and in vitro that mGluR5 receptors are necessary for plasticity in the amygdala.
Members of the Fur protein family regulate iron and zinc transport in E. coli and characteristics of the Fur-regulated fhuF protein.
2002-05-01

The regulator Fur represses with Fe2+ as cofactor iron uptake genes. The fhuF gene reacts very sensitive to minor changes of Fe2+ and Fur. It is assumed that FhuF helps in the mobilisation of iron out of the hydroxamate siderophores transported into the cell. Analysis of the protein revealed an unusual [2Fe-2S] cluster bound to a Cys-Cys-X10-Cys-X2-Cys motif in FhuF. suf genes responsible for the synthesis of the iron sulfur center were identified. The Zur protein shows 27% identity to the Fur protein of E. coli. It regulates as a repressor the high affinity uptake system znuACB. Only two additional Zur binding sites in the promoter region of genes with unknown function were found. Properties of Zur and Fur proteins from different bacteria are compared.