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11.
Blaschuk OW 《Cell and tissue research》2012,348(2):309-313
This article describes over 20 years of research on antagonists of the cell adhesion molecule, N-cadherin. Four types of antagonists are discussed: synthetic linear peptides, synthetic cyclic peptides, non-peptidyl peptidomimetics of the disulfide linked cyclic peptide N-Ac-CHAVC-NH(2) and monoclonal antibodies directed against the N-cadherin ectodomain. The biological activities of these antagonists are also discussed. In particular, the ability of N-cadherin antagonists to act as anti-cancer drugs is considered. 相似文献
12.
The cell adhesion molecule, N-cadherin plays a pivotal role in many biological and disease processes. Drugs that modulate N-cadherin function should therefore be useful therapeutic agents. We have used phage display technology to identify amino acid sequences capable of binding to N-cadherin. All of these sequences harbor a Trp residue in the second position from the N-terminus. A synthetic linear peptide containing one of these sequences, H-SWTLYTPSGQSK-NH(2) was found to bind a chimeric protein composed of the N-cadherin ectodomain fused to the immunoglobulin G1 Fc fragment with an affinity (K(D)) of 10.7microM, as determined by surface plasmon resonance. It also blocked the aggregation of beads coated with this chimeric protein. Furthermore, this peptide disrupted adhesion and tube formation by N-cadherin-expressing human umbilical vein endothelial cells in vitro. These observations suggest that N-cadherin antagonists have the potential of serving as anti-angiogenic agents. The peptide, H-SWTLYTPSGQSK-NH(2) should prove useful for studies designed to evaluate N-cadherin function in various biological processes. 相似文献
13.
Activation of muscle satellite cells in single-fiber cultures. 总被引:2,自引:0,他引:2
Satellite stem cell activation is the process by which quiescent precursor cells resident on muscle fibers are recruited to cycle and move. Two processes are reported to affect satellite cell activation. In vivo, nitric oxide (NO) produced by NO synthase in fibers (NOS-Imu) promotes activation. In cell cultures, hepatocyte growth factor (HGF) is the major activating factor isolated from crushed muscle extract (CME). In this study we hypothesized that distinct and possibly related events were mediated by NO and HGF during activation. Intact fibers were cultured in the presence of bromodeoxyuridine (BrdU) to label DNA synthesis over 48 h. Experiments were designed to test the effects of CME, HGF, a NOS substrate L-arginine, and the NOS inhibitor L-NAME on activation, determined as the number of BrdU-positive satellite cells per fiber. Activation was increased significantly by CME, HGF, and L-arginine. L-Arginine increased activation in a dose-response manner. CME-induced activation was reduced significantly by NOS inhibition. Exposure to marcaine (10 min) caused reversible membrane damage without hypercontraction, as shown by characterizing the sarcolemmal integrity. The resulting decrease in satellite cell activation could be overcome by exogenous HGF. Results support the hypothesis that NO is involved in recruiting to cycle those satellite cells resident on fibers. Separate assessments of resident and free muscle cells showed that HGF and NO also participate in mobilizing satellite cells. Since HGF counteracted NOS inhibition and marcaine-induced membrane damage, data suggest that NO may mediate early steps in activation and precede HGF-mediated events. 相似文献
14.
C-Met expression and mechanical activation of satellite cells on cultured muscle fibers. 总被引:2,自引:0,他引:2
Ashley C Wozniak Orest Pilipowicz Zipora Yablonka-Reuveni Steven Greenway Shauna Craven Elliott Scott Judy E Anderson 《The journal of histochemistry and cytochemistry》2003,51(11):1437-1445
Single-fiber cultures can be used to model satellite cell activation in vivo. Although technical deficiencies previously prevented study of stretch-induced events, here we describe a method developed to study satellite cell gene expression by in situ hybridization (ISH) using protocol modifications for fiber adhesion and fixation. The hypothesis that mechanical stretching activates satellite cells was tested. Fiber cultures were established from normal flexor digitorum brevis muscles and plated on FlexCell dishes with a layer of Vitrogen. After 2 hr of stretch in the presence of BrdU, satellite cells on fibers attached to Vitrogen were activated above control levels. In the absence of activating treatments or mechanical stretch, ISH studies showed 0-6 c-Met+ satellite cells per fiber. Time course experiments demonstrated stable quiescence in the absence of stretch and significant peaks in activation after 30 min and 2 hr of stretch. Frequency distributions for unstretched fiber cultures showed a significantly greater number of quiescent c-Met+ satellite cells than were activated by stretching, suggesting that typical activation stimuli did not trigger cycling in the entire c-Met+ population of satellite cells. These methods have a strong potential to further dissect the nature of stretch-induced activation and gene expression among characterized populations of individual quiescent and activated satellite cells. 相似文献
15.
The hydrogen isotope (2H/1H) ratio of lipids from phytoplankton is a powerful new tool for reconstructing hydroclimate variations in the geologic past from marine and lacustrine sediments. Water 2H/1H changes are reflected in lipid 2H/1H changes with R2 > 0.99, and salinity variations have been shown to cause about a 1‰ change in lipid δ2H values per unit (ppt) change in salinity. Less understood are the effects of growth rate, nutrient limitation and light on 2H/1H fractionation in phytoplankton. Here we present the first published study of growth rate effects on 2H/1H fractionation in the lipids of coccolithophorids grown in continuous cultures. Emiliania huxleyi was cultivated in steady state at four growth rates and the δ2H value of individual alkenones (C37:2, C37:3, C38:2, C38:3), fatty acids (C14:0, C16:0, C18:0), and 24-methyl cholest-5,22-dien-3β-ol (brassicasterol) were measured. 2H/1H fractionation increased in all lipids as growth rate increased by 24‰ to 79‰ (div d-1)-1. We attribute this response to a proportional increase in the fraction of NADPH from Photosystem I (PS1) of photosynthesis relative to NADPH from the cytosolic oxidative pentose phosphate (OPP) pathway in the synthesis of lipids as growth rate increases. A 3-endmember model is presented in which lipid hydrogen comes from NADPH produced in PS1, NADPH produced by OPP, and intracellular water. With published values or best estimates of the fractionation factors for these sources (αPS1 = 0.4, αOPP = 0.75, and αH2O = 0) and half of the hydrogen in a lipid derived from water the model indicates αlipid = 0.79. This value is within the range measured for alkenones (αalkenone = 0.77 to 0.81) and fatty acids (αFA = 0.75 to 0.82) in the chemostat cultures, but is greater than the range for brassicasterol (αbrassicasterol = 0.68 to 0.72). The latter is attributed to a greater proportion of hydrogen from NADPH relative to water in isoprenoid lipids. The model successfully explains the increase in 2H/1H fractionation in the sterol 24-methyl-cholesta-5,24(28)-dien-3β-ol from marine centric diatom T. pseudonana chemostat cultures as growth rate increases. Insensitivity of αFA in those same cultures may be attributable to a larger fraction of hydrogen in fatty acids sourced from intracellular water at the expense of NADPH as growth rate increases. The high sensitivity of α to growth rate in E. huxleyi lipids and a T. pseudonana sterol implies that any change in growth rate larger than ~0.15 div d-1 can cause a change in δ2Hlipid that is larger than the analytical error of the measurement (~5‰), and needs to be considered when interpreting δ2Hlipid variations in sediments. 相似文献
16.
Photocleavable peptide-DNA conjugates: synthesis and applications to DNA analysis using MALDI-MS.
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J Olejnik H C Lüdemann E Krzymanska-Olejnik S Berkenkamp F Hillenkamp K J Rothschild 《Nucleic acids research》1999,27(23):4626-4631
The synthesis and characterization of photocleavable peptide-DNA conjugates is described along with their use as photocleavable mass marker (PCMM) hybridization probes for the detection of target DNA sequences by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Three photocleavable peptide-DNA conjugates were synthesized, purified, and characterized using HPLC and denaturing gel electrophoresis, as well as IR-MALDI and UV-MALDI. The hybridization properties of the conjugates were also studied by monitoring their thermal denaturation with absorption spectroscopy. No significant difference in the melting temperature ( T (m)) of the duplexes was observed between the unmodified duplex and the duplex in which one strand was modified with the photocleavable peptide moiety. These conjugates were evaluated as hybridization probes for the detection of immobilized synthetic target DNAs using MALDI-MS. In these experiments, the DNA portion of the conjugate acts as a hybridization probe, whereas the peptide is photoreleased during the ionization/desorption step of UV-MALDI and can serve as a marker (mass tag) to identify a unique target DNA sequence. The method should be applicable to a wide variety of assays requiring highly multiplexed DNA/RNA analysis, including gene expression monitoring, genetic profiling and the detection of pathogens. 相似文献
17.
Iveta Ondrejkovi?ová Jerzy Mroziński Julia K?ak Zofia Olejnik 《Inorganica chimica acta》2008,361(8):2483-2490
The iron(II) compound of formula [Fe(NCS)2(dena)2]n (dena = N,N′-diethylnicotinamide) has been prepared by the reaction between iron(III) thiocyanate and dena in ethanol solution. The complex was characterized by elemental analysis, spectral and magnetic measurements. Single-crystal X-ray diffraction methods show that the complex, crystallizing in the triclinic space group, undergoes a phase transition between 220 K and 230 K, connected with the doubling of cell volume. Crystal structures at 230 K (1a; HT phase) and 150 K (1b; LT phase) are described and a transition mechanism is discussed. In both phases the compound has an extended chain structure, in which the neutral molecule of N,N′-diethylnicotinamide acts as a bridging ligand binding through pyridine N atom to one centre and through amide O atom to the neighbouring Fe centre. The Fe2+ ion has a slightly distorted trans-octahedral environment with FeO2N4 chromophore, and all Fe-O and Fe-N bonds in the typical for high-spin iron(II) compounds range. Variable-temperature magnetic susceptibility data in the temperature range 1.8-300 K show that iron(II) is high-spin S = 2(5T2g) and as a result effects due to zero-field splitting are anticipated at low temperatures. The IR spectrum suggested the coordination of N,N′-diethylnicotinamide to the central atom of iron(II) as a bridging ligand and NCS group as a monodentate ligand. 相似文献
18.
Miroslav Balaz Marek Vician Zuzana Janakova Timea Kurdiova Martina Surova Richard Imrich Zuzana Majercikova Adela Penesova Miroslav Vlcek Alexander Kiss Vitazoslav Belan Iwar Klimes Juraj Olejnik Daniela Gasperikova Christian Wolfrum Barbara Ukropcova Jozef Ukropec 《Obesity (Silver Spring, Md.)》2014,22(8):1821-1829
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20.
Hutter D Kim MJ Karalkar N Leal NA Chen F Guggenheim E Visalakshi V Olejnik J Gordon S Benner SA 《Nucleosides, nucleotides & nucleic acids》2010,29(11):879-895
Nucleoside triphosphates having a 3'-ONH? blocking group have been prepared with and without fluorescent tags on their nucleobases. DNA polymerases were identified that accepted these, adding a single nucleotide to the 3'-end of a primer in a template-directed extension reaction that then stops. Nitrite chemistry was developed to cleave the 3'-ONH? group under mild conditions to allow continued primer extension. Extension-cleavage-extension cycles in solution were demonstrated with untagged nucleotides and mixtures of tagged and untagged nucleotides. Multiple extension-cleavage-extension cycles were demonstrated on an Intelligent Bio-Systems Sequencer, showing the potential of the 3'-ONH? blocking group in "next generation sequencing." 相似文献