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991.
Michal Hofer Milan Pospíšil Zuzana Hoferová Denisa Komůrková Petr Páral Filipp Savvulidi Luděk Šefc 《Purinergic signalling》2013,9(2):207-214
This study continues our earlier findings on the hematopoiesis-modulating effects of adenosine A1 and A3 receptor agonists that were performed on committed hematopoietic progenitor and precursor cell populations. In the earlier experiments, N 6-cyclopentyladenosine (CPA), an adenosine A1 receptor agonist, was found to inhibit proliferation in the above-mentioned hematopoietic cell systems, whereas N 6-(3-iodobenzyl)adenosine-5′-N-methyluronamide (IB-MECA), an adenosine A3 receptor agonist, was found to stimulate it. The topic of this study was to evaluate the possibility that the above-mentioned adenosine receptor agonists modulate the behavior of early hematopoietic progenitor cells and hematopoietic stem cells. Flow cytometric analysis of hematopoietic stem cells in mice was employed, as well as a functional test of hematopoietic stem and progenitor cells (HSPCs). These techniques enabled us to study the effect of the agonists on both short-term repopulating ability and long-term repopulating ability, representing multipotent progenitors and hematopoietic stem cells, respectively. In a series of studies, we did not find any significant effect of adenosine agonists on HSPCs in terms of their numbers, proliferation, or functional activity. Thus, it can be concluded that CPA and IB-MECA do not significantly influence the primitive hematopoietic stem and progenitor cell pool and that the hematopoiesis-modulating action of these adenosine receptor agonists is restricted to more mature compartments of hematopoietic progenitor and precursor cells. 相似文献
992.
Michal Sobkowski Adam Kraszewski Jacek Stawiński 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):253-267
Abstract Three methods for the functionalization of oligonucleotides with aminoalkyl moieties have been developed and their efficiencies were evaluated in the preparation of non-radioactive hybridization probes. 相似文献
993.
Michal Sobkowski Jacek Stawinski Adam Kraszewski 《Nucleosides, nucleotides & nucleic acids》2013,32(8):628-645
Efficiency and stereoselectivity of condensations of ribonucleoside 3′-H-phosphonates with ethanol promoted by pivaloyl chloride were investigated as a function of tertiary amines used. Side reactions leading to an increased demand for the condensing agent were identified as derived from an attack of the pivalate anion at carbonyl centers of reactive pivaloyl derivatives. The conditions that secured quantitative yields of H-phosphonate diester condensations were assessed. Several tertiary amines promoted condensations with stereoselectivity higher than that observed for pyridine derivatives. A correlation between diastereoselectivity of the product formation and Brønsted and H-bonding basicities of the amine used was found. 相似文献
994.
995.
996.
Syam Prakash Somasekharan Michal Koc Alexandre Morizot Olivier Micheau Poul H. B. Sorensen Olivier Gaide Ladislav Andera Jean-Claude Martinou 《Apoptosis : an international journal on programmed cell death》2013,18(3):324-336
Recently, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/Apo2L) has been shown to be a potential candidate for cancer therapy. TRAIL induces apoptosis in various cancer cells but not in normal tissues. Here we show that HCT116 and SW480 cells with a deficient mitochondrial apoptotic pathway were resistant to TRAIL-induced apoptosis, whereas HCT116 and SW480 cells with a functional mitochondrial apoptotic pathway underwent apoptosis upon exposure to TRAIL. Surprisingly, TRAIL induced phenotypic changes in cells with a dysfunctional mitochondrial apoptotic pathway, including membrane blebbing and a transient loss of adhesion properties to the substratum. Accordingly, TRAIL stimulated the ability of these cells to migrate. This behavior was the consequence of a transient TRAIL-induced ROCK1 cleavage. In addition, we report that Bax-deficient HCT116 cells exposed to TRAIL for a prolonged period lost their sensitivity to TRAIL as a result of downregulation of TRAIL receptor expression, and became resistant to combination of TRAIL and other drugs such as MG-132 and bortezomib. These findings may have important consequences for TRAIL anti-cancer therapy. 相似文献
997.
Lenka Beranova Antonio R. Pombinho Jarmila Spegarova Michal Koc Magdalena Klanova Jan Molinsky Pavel Klener Petr Bartunek Ladislav Andera 《Apoptosis : an international journal on programmed cell death》2013,18(6):739-750
TNF-related apoptosis-inducing ligand (TRAIL) is a pro-apoptotic ligand from the TNF-alpha family that is under consideration, along with agonistic anti-TRAIL receptor antibodies, as a potential anti-tumor agent. However, most primary human tumors are resistant to monotherapy with TRAIL apoptogens, and thus the potential applicability of TRAIL in anti-tumor therapy ultimately depends on its rational combination with drugs targeting these resistances. In our high-throughput screening for novel agents/drugs that could sensitize TRAIL-resistant colorectal cancer cells to TRAIL-induced apoptosis, we found homoharringtonine (HHT), a cephalotaxus alkaloid and tested anti-leukemia drug, to be a very effective, low nanomolar enhancer of TRAIL-mediated apoptosis/growth suppression of these resistant cells. Co-treatment of TRAIL-resistant RKO or HT-29 cells with HHT and TRAIL led to the effective induction of apoptosis and the complete elimination of the treated cells. HHT suppressed the expression of the anti-apoptotic proteins Mcl-1 and cFLIP and enhanced the TRAIL-triggered activation of JNK and p38 kinases. The shRNA-mediated down-regulation of cFLIP or Mcl-1 in HT-29 or RKO cells variably enhanced their TRAIL-induced apoptosis but it did not markedly sensitize them to TRAIL-mediated growth suppression. However, with the notable exception of RKO/sh cFLIP cells, the downregulation of cFLIP or Mcl-1 significantly lowered the effective concentration of HHT in HHT + TRAIL co-treatment. Combined HHT + TRAIL therapy also led to the strong suppression of HT-29 tumors implanted into immunodeficient mice. Thus, HHT represents a very efficient enhancer of TRAIL-induced apoptosis with potential application in TRAIL-based, anti-cancer combination therapy. 相似文献
998.
Jolanta Dorszewska Michal Prendecki Anna Oczkowska Agata Rozycka Margarita Lianeri Wojciech Kozubski 《Current Genomics》2013,14(8):518-533
Epinephrine (E) and sympathetic nerve stimulation were described
by Thomas Renton Elliott in 1905 for the
first time. Dopamine (DA), norepinephrine (NE), E, and serotonin
(5-HT) belong to the classic biogenic amines (or monoamines).
Parkinson’s disease (PD) is among the diseases in which it has
been established that catecholamines may account
for the neurodegeneration of central and peripheral
catecholamine neural systems. PD is a chronic and progressive
neurological disorder characterized by resting tremor, rigidity,
and bradykinesia, affecting 2% of individuals above the
age of 65 years. This disorder is a result of degeneration of
DA-producing neurons of the substantia nigra and a significant
loss of noradrenergic neurons in the locus coeruleus. In
PD and other related neurodegerative diseases, catecholamines
play the role of endogenous neurotoxins.
Catechol-O-methyltransferase (COMT) and/or monoamine oxidase
(MAO) catalyze the metabolism of monoamines. However, the
monoamine transporters for DA, NE, and 5-HT namely
DAT, NET, and SERT, respectively regulate the monoamine
concentration. The metabolism of catecholamines and 5-HT
involves common factors. Monoamine transporters represent
targets for many pharmacological agents that affect brain
function, including psychostimulators and antidepressants. In
PD, polymorphisms of the COMT, MAO, DAT, NET, and 5-
HTT genes may change the levels of biogenic amines and their
metabolic products. The currently available therapies for
PD improve the symptoms but do not halt the progression of the
disease. The most effective treatment for PD patients is
therapy with L-dopa. Combined therapy for PD involves a DA
agonist and decarboxylase, MAOs and COMT inhibitors,
and is the current optimal form of PD treatment maintaining monoamine
balance. 相似文献
999.
Michal Bohdanowicz Daniel Schlam Martin Hermansson David Rizzuti Gregory D. Fairn Takehiko Ueyama Pentti Somerharju Guangwei Du Sergio Grinstein 《Molecular biology of the cell》2013,24(11):1700-1712
Macrophages and dendritic cells continuously survey their environment in search of foreign particles and soluble antigens. Such surveillance involves the ongoing extension of actin-rich protrusions and the consequent formation of phagosomes and macropinosomes. The signals inducing this constitutive cytoskeletal remodeling have not been defined. We report that, unlike nonphagocytic cells, macrophages and immature dendritic cells have elevated levels of phosphatidic acid (PA) in their plasma membrane. The plasmalemmal PA is synthesized by phosphorylation of diacylglycerol, which is in turn generated by a G protein–stimulated phospholipase C. Inhibition of diacylglycerol kinase activity results in the detachment of T-cell lymphoma invasion and metastasis–inducing protein 1 (TIAM1)—a Rac guanine exchange factor—from the plasma membrane, thereby depressing Rac activity and abolishing the constitutive ruffling and macropinocytosis that characterize macrophages and immature dendritic cells. Accumulation of PA and binding of TIAM1 to the membrane require the activity of phosphatidylinositol-4,5-bisphosphate 3-kinase. Thus a distinctive, constitutive pathway of PA biosynthesis promotes the actin remodeling required for immune surveillance. 相似文献
1000.
Michal Be'ery-Lipperman 《Computer methods in biomechanics and biomedical engineering》2013,16(1):35-44
Stress shielding is a biomechanical phenomenon causing adaptive changes in bone strength and stiffness around metallic implants, which potentially lead to implant loosening. Accordingly, there is a need for standard, objective engineering measures of the “stress shielding” performances of an implant that can be employed in the process of computer-aided implant design. To provide and test such measures, we developed hierarchical computational models of adaptation of the trabecular microarchitecture at different sites in the proximal femur, in response to insertion of orthopaedic screws and in response to hypothetical reductions in hip joint and gluteal muscle forces. By identifying similar bone adaptation outcomes from the two scenarios, we were able to quantify the stress shielding caused by screws in terms of analogous hypothetical reductions in hip joint and gluteal muscle forces. Specifically, we developed planar lattice models of trabecular microstructures at five regions of interest (ROI) in the proximal femur. The homeostatic and abnormal loading conditions for the lattices were determined from a finite element model of the femur at the continuum scale and fed to an iterative algorithm simulating the adaptation of each lattice to these loads. When screws were inserted to the femur model, maximal simulated bone loss (17% decrease in apparent density, 10% decrease in thickness of trabeculae) was at the greater trochanter and this effect was equivalent to the effect of 50% reduction in gluteal force and normal hip joint force. We conclude that stress shielding performances can be quantified for different screw designs using model-predicted hypothetical musculoskeletal load fractions that would cause a similar pattern and extent of bone loss to that caused by the implants. 相似文献