排序方式: 共有177条查询结果,搜索用时 15 毫秒
61.
A dermal niche for multipotent adult skin-derived precursor cells 总被引:17,自引:0,他引:17
Fernandes KJ McKenzie IA Mill P Smith KM Akhavan M Barnabé-Heider F Biernaskie J Junek A Kobayashi NR Toma JG Kaplan DR Labosky PA Rafuse V Hui CC Miller FD 《Nature cell biology》2004,6(11):1082-1093
A fundamental question in stem cell research is whether cultured multipotent adult stem cells represent endogenous multipotent precursor cells. Here we address this question, focusing on SKPs, a cultured adult stem cell from the dermis that generates both neural and mesodermal progeny. We show that SKPs derive from endogenous adult dermal precursors that exhibit properties similar to embryonic neural-crest stem cells. We demonstrate that these endogenous SKPs can first be isolated from skin during embryogenesis and that they persist into adulthood, with a niche in the papillae of hair and whisker follicles. Furthermore, lineage analysis indicates that both hair and whisker follicle dermal papillae contain neural-crest-derived cells, and that SKPs from the whisker pad are of neural-crest origin. We propose that SKPs represent an endogenous embryonic precursor cell that arises in peripheral tissues such as skin during development and maintains multipotency into adulthood. 相似文献
62.
Valipour Mahnaz Johnson Chris E. Battles John J. Campbell John L. Fahey Timothy J. Fakhraei Habibollah Driscoll Charles T. 《Biogeochemistry》2022,157(2):131-148
Biogeochemistry - The biogeochemical model, PnET-BGC, was modified and parameterized using field data from an experimental whole-tree harvest of watershed (W5) in 1983–1984 at the Hubbard... 相似文献
63.
Asho Ali Zahra Hasan Mahnaz Tanveer Amna R Siddiqui Solomon Ghebremichael Gunilla Kallenius Rumina Hasan 《BMC microbiology》2007,7(1):76
Background
The Central Asian Strain1 (CAS1) genogroup of Mycobacterium tuberculosis (MTB) is the most prevalent in Pakistan, India and Bangladesh. Mycobacterial interspersed repetitive units variable number tandem repeat (MIRU-VNTR) typing is a reliable and reproducible method for differentiation of MTB isolates. However, information of its utility in determining the diversity of CAS1 strain is limited. We performed standard 12 loci based MIRU-VNTR typing on previously spoligotyped CAS1 strains and 'unique' strains in order to evaluate its discriminatory power for these isolates. 相似文献64.
Shirazy NH Ranjbar B Hosseinkhani S Khalifeh K Madvar AR Naderi-Manesh H 《Journal of biochemistry and molecular biology》2007,40(4):453-458
Bacterial luciferase is a heterodimeric enzyme, which catalyzes the light emission reaction, utilizing reduced FMN (FMNH2), a long chain aliphatic aldehyde and O(2), to produce green-blue light. This enzyme can be readily classed as slow or fast decay based on their rate of luminescence decay in a single turnover. Mutation of Glu175 in alpha subunit to Gly converted slow decay Xenorhabdus Luminescence luciferase to fast decay one. The following studies revealed that changing the luciferase flexibility and lake of Glu-flavin interactions are responsible for the unusual kinetic properties of mutant enzyme. Optical and thermodynamics studies have caused a decrease in free energy and anisotropy of mutant enzyme. Moreover, the role of Glu175 in transition state of folding pathway by use of stopped-flow fluorescence technique has been studied which suggesting that Glu175 is not involved in transition state of folding and appears as surface residue of the nucleus or as a member of one of a few alternative folding nuclei. These results suggest that mutation of Glu175 to Gly extended the structure of Xenorhabdus Luminescence luciferase, locally. 相似文献
65.
Hanieh Kamyab Shohreh Hejrati Mahnaz Khanavi Farshad Malihi Azadeh Mohammadirad Maryam Baeeri Hadi Esmaily Mohammad Abdollahi 《Central European Journal of Biology》2010,5(3):304-309
The present study was designed to explore the mechanism of action of walnut (the seed of Juglans regia) leaf and ridge on hepatic glucose metabolism in diabetic mice. Experimental diabetes was induced by intravenous administration of streptozotocin (60 mg/kg)and confirmed with an increase of blood glucose, 90–100% of the control, 72 hours later. Isolated extracts from walnut leaf and ridges were administered in a single effective dose of 400 mg/kg orally. Firstly, blood glucose was determined every 1 hour until 5 hours post administration of extracts. In the second experiment, the liver was surgically removed, 2 hours post treatment of diabetic animals with extracts, homogenized and used for measurement of key enzymes of glycogenolysis (glycogen phosphorylase, GP) and gluconeogenesis (phosphoenolpyruvate carboxykinase, PEPCK). Treatment by both leaf and ridge extracts decreased blood glucose and liver PEPCK activity and increased blood insulin and liver GP activity. It is concluded that walnut is able to lower blood glucose through inhibition of hepatic gluconeogenesis and secretion of pancreatic insulin. 相似文献
66.
Steroid hormones have been reported to indirectly impact mitochondrial functions, attributed to nuclear receptor-induced production of proteins that localize in this cytoplasmic organelle. Here we show high-affinity estrogen receptors in the mitochondria of MCF-7 breast cancer cells and endothelial cells, compatible with classical estrogen receptors ERalpha and ERbeta. We report that in MCF-7, estrogen inhibits UV radiation-induced cytochrome C release, the decrease of the mitochondrial membrane potential, and apoptotic cell death. UV stimulated the formation of mitochondrial reactive oxygen species (mROS), and mROS were essential to inducing mitochondrial events of cell death. mROS mediated the UV activation of c-jun N-terminal kinase (JNK), and protein kinase C (PKC) delta, underlying the subsequent translocation of Bax to the mitochondria where oligomerization was promoted. E2 (estradiol) inhibited all these events, directly acting in mitochondria to inhibit mROS by rapidly up-regulating manganese superoxide dismutase activity. We implicate novel functions of ER in the mitochondria of breast cancer that lead to the survival of the tumor cells. 相似文献
67.
Michel Varrin-Doyer Peggy Vincent Sylvie Cavagna Nathalie Auvergnon Nelly Noraz Véronique Rogemond Jér?me Honnorat Mahnaz Moradi-Améli Pascale Giraudon 《The Journal of biological chemistry》2009,284(19):13265-13276
In the central nervous system, collapsin response mediator protein 2
(CRMP2) is a transducer protein that supports the semaphorin-induced guidance
of axons toward their cognate target. However, we previously showed that CRMP2
is also expressed in immune cells and plays a crucial role in T lymphocyte
migration. Here we further investigated the molecular mechanisms underlying
CRMP2 function in chemokine-directed T-cell motility. Examining Jurkat T-cells
treated with the chemokine CXCL12, we found that 1) CXCL12 induces a dynamic
re-localization of CRMP2 to uropod, the flexible structure of migrating
lymphocyte, and increases its binding to the cytoskeletal protein vimentin; 2)
CXCL12 decreases phosphorylation of the glycogen synthase
kinase-3β-targeted residues CRMP2-Thr-509/514; and 3) tyrosine Tyr-479 is
a new phosphorylation CRMP2 residue and a target for the Src-family kinase
Yes. Moreover, phospho-Tyr-479 increased under CXCL12 signaling while
phospho-Thr-509/514 decreased. The functional importance of this tyrosine
phosphorylation was demonstrated by Y479F mutation that strongly reduced
CXCL12-mediated T-cell polarization and motility as tested in a transmigration
model and on neural tissue. We propose that differential phosphorylation by
glycogen synthase kinase-3β and Yes modulates the contribution of CRMP2
to cytoskeletal reorganization during chemokine-directed T-cell migration. In
addition to providing a novel mechanism for T lymphocyte motility, our
findings reveal CRMP2 as a transducer of chemokine signaling.T lymphocyte migration is the basis of major immune functions such as
responses to infection and inflammation, as well as normal recirculation
through the lymphoid organs. Indeed, the role of T-cells depends strongly on
their ability to travel between organs via the blood and lymph and to move
rapidly within these tissues, by extravasation
(1). This latter function is
dependent on extracellular signals, among which chemokines play a major
role.Chemokines form a superfamily of small proteins that orchestrate lymphocyte
polarization and migration (2).
These proteins exert their functions by binding specific
seven-transmembrane-domain G-protein-coupled receptors on the T-cell surface
(3). T-lymphocytes exposed to
chemokines, in a soluble or surface-bound gradient, develop a polarized shape,
extending at the front, an F-actin-rich lamellipodium, which constitutes the
leading edge, and a trailing edge or uropod in which both the microtubule and
vimentin networks are retracted during migration. Although F-actin has the
well known function of producing the mechanical forces required to generate
movement (4), the role of
microtubules and vimentin in T-cell migration requires further
investigation.Cytoskeletal remodeling is of key importance in migrating cells
(5) and is one of the functions
carried out by the chemokine stromal cell-derived factor-1α, also named
CXCL12. In association with its cognate receptor CXCR4, CXCL12 is a potent
chemoattractant for mature T-cells and monocytes
(6). Following ligand
recognition and binding, CXCR4 signaling starts with the activation of G
proteins, followed by various signaling cascade effectors, including
MAP2 kinases,
phosphoinositide 3-kinase, and phospholipase Cγ
(7). Although this
intracellular signaling cascade has not been completely elucidated, the Src
family non-receptor tyrosine kinase Lck and the Syk kinase ZAP-70 have emerged
as the main candidates for delivering the input signal following CXCR4
activation (8). Thus, tyrosine
kinase activity appears as a central step in CXCR4-dependent chemotaxis.While searching for molecules involved in T-cell motility, we recently
identified collapsin response mediator protein 2 (CRMP2)
(9), a protein first described
in the context of neuronal growth cone advance
(10,
11). We demonstrated that
CRMP2 regulated both T-cell polarization and spontaneous/chemokine-induced
migration of T-lymphocytes. Moreover, CRMP2 was found at the uropod of motile
T-cells and has the ability to bind cytoskeletal elements, including vimentin.
A correlation between CRMP2 expression levels and cell migratory rates toward
a chemokine gradient, including CXCL12, was demonstrated by overexpression and
knockdown experiments in T-cells
(9). In addition, we recently
reported that, in mouse model of neuroinflammation, elevated CRMP2 expression
in T lymphocytes correlated with their elevated migratory rates and their
ability to target the central nervous system
(12). The importance of CXCL12
in the central nervous system and its implication in the pathogenesis of
central nervous system disorders, including neuroinflammatory diseases, are
well documented (review in Ref.
13). Thus, the aim of the
present study was to determine whether and how CRMP2 participates in the
transduction pathway induced by CXCL12 on T lymphocytes. 相似文献
68.
The Lower Jurassic genus Eodasycladus is discussed according to the characters of type species and compared with the other species known in the literature. The architecture of two species attributed to the genus Palaeodasycladus, P. alanensis Soka?, and P. benceki Soka?, is examined and an alternative organization of the thallus is prospected. P. alanensis is considered a valid species, but its characters require to transfer the taxon to the genus Eodasycladus. P. benceki is considered synonymous with P. alanensis. 相似文献
69.
70.
Reza Hadjiaghaie Vafaie Mahnaz Mehdipoor Adel Pourmand Elnaz Poorreza Habib Badri Ghavifekr 《Biotechnology and Bioprocess Engineering》2013,18(3):594-605
In order to offer the ability of smaller volumes and high throughput in Lab-On-a-Chip and micro Total Analysis Systems devices, more miniaturized components are needed. Due to a low Reynolds number on the microscale, the mixing process can be particularly troublesome. This problem is compounded by the fact that more miniaturization can be challenging in a microfluidic system. In such a case, electroosmotic (EO) force is an efficient force to perturb low Reynolds number fluid. In this paper, a novel Micro-Electro-Mechanical-Systems (MEMS) based fabrication for microfluidic devices, and a more miniaturized micromixer are presented. The proposed technology process requires the covering of excited electrode patterns by a thin Silicon-Nitride (Si3N4) insulator layer. Fabrication parameters such as Low Pressure Chemical Vapor Deposition (LPCVD) Si3N4 deposition effect, and height of the Phosphor Silicate Glass (PSG) sacrificial layer were investigated for the electroosmotically-driven mixer. Particle tracing for fluid flow was illustrated, the particles were stretched and folded for a long time, which was a proof of chaotic regime. Finite Element Analysis (FEA) revealed that the mixer with covered electrodes provides the high mixing efficiency of above 90% for a 96 μm long microchannel. Using a silicon nitride insulator layer reduces high electric field gradient at sharp corners and edges of the electrodes, leading to the elimination of unwanted electrolyte effects. Thus, the excitation and geometrical parameters were optimized for the micromixer. 相似文献