排序方式: 共有168条查询结果,搜索用时 15 毫秒
21.
Coughlin MF Puig-de-Morales M Bursac P Mellema M Millet E Fredberg JJ 《Biophysical journal》2006,90(6):2199-2205
Here we report the rheological properties of cultured hsFLNa (filamin-A)-expressing (FIL+) and hsFLNa-deficient (FIL-) melanoma cells. Using magnetic twisting cytometry over a wide range of probing frequencies, and targeting either cortical or deeper cytoskeletal structures, we found that differences in stiffness of FIL+ versus FIL- cells were remarkably small. When probed through deep cytoskeletal structures, FIL+ cells were, at most, 30% stiffer than FIL- cells, whereas when probed through more peripheral cytoskeletal structures FIL- cells were not different except at very high frequencies. The loss tangent, expressed as an effective cytoskeletal temperature, was systematically greater in FIL- than FIL+ cells, but these differences were small and showed that the FIL+ cells were only slightly closer to a solidlike state. To quantify cytoskeletal remodeling, we measured spontaneous motions of beads bound to cortical cytoskeletal structures and found no difference in FIL+ versus FIL- cells. Although mechanical differences between FIL+ and FIL- cells were evident both in cortical and deeper structures, these differences were far smaller than expected based on measurements of the rheology of purified actin-filamin solutions. These findings do not rule out an important contribution of filamin to the mechanical properties of the cortical cytoskeleton, but suggest that effects of filamin in the cortex are not exerted on the length scale of the probe used here. These findings would appear to rule out any important contribution of filamin to the bulk mechanical properties of the cytoplasm, however. Although filamin is present in the cytoplasm, it may be inactive, its mechanical effects may be small compared with other crosslinkers, or mechanical properties of the matrix may be dominated by an overriding role of cytoskeletal prestress. 相似文献
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Dragomir Marisavljevi Peter Antunovi Predrag Milji Milena Panti 《Cancer immunology, immunotherapy : CII》1998,15(4):275-278
A 71-year-old male patient with atypical myelodysplastic syndrome showing monosomy 7 is described. He presented with severe
foot pains, trophic skin and nail changes, loss of distal pulses, all compatible with peripheral arterial occlusive disease.
He had completely normal blood counts and no bleeding tendency. Prolonged bleeding time was disclosed by chance, during routine
haemostatic studies. An acquired platelet dysfunction was considered, with prolonged bleeding time and large platelets that
failed to aggregate in response to arachidonic acid and that had impaired response to collagen and adrenaline. The bone marrow
was hypercellular, with numerous dysplastic megakaryocytes and two other slightly dysplastic myeloid lines. Cytogenetic analyses
of the bone marrow cells showed a mosaic karyotype: 46,XY/45,XY,-7. On angiography, bilateral thrombosis of the iliac, superficial
femoral and popliteal arteries was disclosed. The patient was prepared with platelet transfusions. Arterial thrombectomy and
amputation of the left calf were performed. Ten months later, his blood counts showed mild pancytopenia. He died at home.
The authors discuss some clinical and pathogenetical aspects of such presentations of myelodysplastic syndromes. 相似文献
26.
Momir M. Paunovic Dunja G. Jakovcev-Todorovic Vladica M. Simic Bojana D. Stojanovic Predrag D. Cakic 《Biologia》2007,62(2):214-221
Results of the investigation of the aquatic macroinvertebrate fauna along a 504 km stretch of the Danube River in Serbia are
presented. A total of 74 macroinvertebrate taxa were observed during a 2001 survey. Oligochaeta and Mollusca were the principal
components of the community with regard to species richness and abundance. Based on data on the qualitative composition of
the macroinvertebrate fauna, a correspondence analysis divided the investigated stretch in three sectors — upper (Pannonian),
Iron Gate sector and entrance sector to the Iron Gate stretch. The distribution patterns of certain species supported the
division of sectors defined by correspondence analysis. 相似文献
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Bursac P Fabry B Trepat X Lenormand G Butler JP Wang N Fredberg JJ An SS 《Biochemical and biophysical research communications》2007,355(2):324-330
Out-of-equilibrium systems, such as the dynamics of a living cytoskeleton (CSK), are inherently noisy with fluctuations arising from the stochastic nature of the underlying biochemical and molecular events. Recently, such fluctuations within the cell were characterized by observing spontaneous nano-scale motions of an RGD-coated microbead bound to the cell surface [Bursac et al., Nat. Mater. 4 (2005) 557-561]. While these reported anomalous bead motions represent a molecular level reorganization (remodeling) of microstructures in contact with the bead, a precise nature of these cytoskeletal constituents and forces that drive their remodeling dynamics are largely unclear. Here, we focused upon spontaneous motions of an RGD-coated bead and, in particular, assessed to what extent these motions are attributable to (i) bulk cell movement (cell crawling), (ii) dynamics of focal adhesions, (iii) dynamics of lipid membrane, and/or (iv) dynamics of the underlying actin CSK driven by myosin motors. 相似文献
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Lenormand G Chopin J Bursac P Fredberg JJ Butler JP 《Biochemical and biophysical research communications》2007,360(4):797-801
We report directional memory of spontaneous nanoscale displacements of an individual bead firmly anchored to the cytoskeleton of a living cell. A novel method of analysis shows that for shorter time intervals cytoskeletal displacements are antipersistent and thus provides direct evidence in a living cell of molecular trapping and caged dynamics. At longer time intervals displacements are persistent. The transition from antipersistence to persistence is indicative of a time-scale for cage rearrangements and is found to depend upon energy release due to ATP hydrolysis and proximity to a glass transition. Anomalous diffusion is known to imply memory, but we show here that memory is attributed to direction rather than step size. As such, these data are the first to provide a molecular-scale physical picture describing the cytoskeletal remodelling process and its rate of progression. 相似文献
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Length-dependent prediction of protein intrinsic disorder 总被引:2,自引:0,他引:2
Kang Peng Predrag Radivojac Slobodan Vucetic A Keith Dunker Zoran Obradovic 《BMC bioinformatics》2006,7(1):208-17
Background
Due to the functional importance of intrinsically disordered proteins or protein regions, prediction of intrinsic protein disorder from amino acid sequence has become an area of active research as witnessed in the 6th experiment on Critical Assessment of Techniques for Protein Structure Prediction (CASP6). Since the initial work by Romero et al. (Identifying disordered regions in proteins from amino acid sequences, IEEE Int. Conf. Neural Netw., 1997), our group has developed several predictors optimized for long disordered regions (>30 residues) with prediction accuracy exceeding 85%. However, these predictors are less successful on short disordered regions (≤30 residues). A probable cause is a length-dependent amino acid compositions and sequence properties of disordered regions. 相似文献30.