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Spatial Localization (spatial + localization)
Selected AbstractsDirect Evidence of High Spatial Localization of Hot Spots in Surface-Enhanced Raman Scattering,ANGEWANDTE CHEMIE, Issue 52 2009Chang Chen Heiß oder kalt: Die hohe Lokalisierung in SERS-Hotspots lässt sich direkt anhand der selektiven Ablagerung von Raman-Analyten innerhalb und außerhalb von Regionen mit verstärktem Feld in einem Spalt zeigen (siehe Bild). Dies bestätigen Messungen der absoluten SERS-Intensitäten ebenso wie kinetische Studien zum lichtinduzierten Abbau an unterschiedlichen Stellen. [source] Fast proton spectroscopic imaging using steady-state free precession methodsMAGNETIC RESONANCE IN MEDICINE, Issue 3 2003Wolfgang Dreher Abstract Various pulse sequences for fast proton spectroscopic imaging (SI) using the steady-state free precession (SSFP) condition are proposed. The sequences use either only the FID-like signal S1, only the echo-like signal S2, or both signals in separate but adjacent acquisition windows. As in SSFP imaging, S1 and S2 are separated by spoiler gradients. RF excitation is performed by slice-selective or chemical shift-selective pulses. The signals are detected in absence of a B0 gradient. Spatial localization is achieved by phase-encoding gradients which are applied prior to and rewound after each signal acquisition. Measurements with 2D or 3D spatial resolution were performed at 4.7 T on phantoms and healthy rat brain in vivo allowing the detection of uncoupled and J-coupled spins. The main advantages of SSFP based SI are the short minimum total measurement time (Tmin) and the high signal-to-noise ratio per unit measurement time (SNRt). The methods are of particular interest at higher magnetic field strength B0, as TR can be reduced with increasing B0 leading to a reduced Tmin and an increased SNRt. Drawbacks consist of the limited spectral resolution, particularly at lower B0, and the dependence of the signal intensities on T1 and T2. Further improvements are discussed including optimized data processing and signal detection under oscillating B0 gradients leading to a further reduction in Tmin. Magn Reson Med 50:453,460, 2003. © 2003 Wiley-Liss, Inc. [source] Expression patterns of hormones, signaling molecules, and transcription factors during adenohypophysis development in the chick embryoDEVELOPMENTAL DYNAMICS, Issue 4 2010Nicole Parkinson Abstract The chick embryo is an ideal model to study pituitary cell-type differentiation. Previous studies describing the temporal appearance of differentiated pituitary cell types in the chick embryo are contradictory. To resolve these controversies, we used RT-PCR to define the temporal onset and in situ hybridization and immunohistochemistry to define the spatial localization of hormone expression within the pituitary. RT-PCR detected low levels of Fsh, (gonadotropes) and Pomc (corticotropes, melanotropes) mRNA at E4 and Gh (somatotropes), Prl (lactotropes), and Tsh, (thyrotropes) mRNA at E8. For all hormones, sufficient accumulation of mRNA and/or protein to permit detection by in situ hybridization or immunohistochemistry was observed ,3 days later and in all cases corresponded to a notable increase in RT-PCR product. We also describe the expression patterns of signaling (Bmp2, Bmp4, Fgf8, Fgf10, Shh) and transcription factors (Pitx1, Pitx2, cLim3) known to be important for pituitary organogenesis in other model organisms. Developmental Dynamics 239:1197,1210, 2010. © 2010 Wiley-Liss, Inc. [source] SCALES: a large-scale assessment model of soil erosion hazard in Basse-Normandie (northern-western France)EARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2010P. Le Gouée Abstract The cartography of erosion risk is mainly based on the development of models, which evaluate in a qualitative and quantitative manner the physical reproduction of the erosion processes (CORINE, EHU, INRA). These models are mainly semi-quantitative but can be physically based and spatially distributed (the Pan-European Soil Erosion Risk Assessment, PESERA). They are characterized by their simplicity and their applicability potential at large temporal and spatial scales. In developing our model SCALES (Spatialisation d'éChelle fine de l'ALéa Erosion des Sols/large-scale assessment and mapping model of soil erosion hazard), we had in mind several objectives: (1) to map soil erosion at a regional scale with the guarantee of a large accuracy on the local level, (2) to envisage an applicability of the model in European oceanic areas, (3) to focus the erosion hazard estimation on the level of source areas (on-site erosion), which are the agricultural parcels, (4) to take into account the weight of the temporality of agricultural practices (land-use concept). Because of these objectives, the nature of variables, which characterize the erosion factors and because of its structure, SCALES differs from other models. Tested in Basse-Normandie (Calvados 5500,km2) SCALES reveals a strong predisposition of the study area to the soil erosion which should require to be expressed in a wet year. Apart from an internal validation, we tried an intermediate one by comparing our results with those from INRA and PESERA. It appeared that these models under estimate medium erosion levels and differ in the spatial localization of areas with the highest erosion risks. SCALES underlines here the limitations in the use of pedo-transfer functions and the interpolation of input data with a low resolution. One must not forget however that these models are mainly focused on an interregional comparative approach. Therefore the comparison of SCALES data with those of the INRA and PESERA models cannot result on a convincing validation of our model. For the moment the validation is based on the opinion of local experts, who agree with the qualitative indications delivered by our cartography. An external validation of SCALES is foreseen, which will be based on a thorough inventory of erosion signals in areas with different hazard levels. Copyright © 2010 John Wiley & Sons, Ltd. [source] Visualization of Helicobacter Species Within the Murine Cecal Mucosa Using Specific Fluorescence In Situ HybridizationHELICOBACTER, Issue 2 2005Vivian Chan ABSTRACT Background., Members of the genus Helicobacter have been associated with colitis development in a number of immunodeficient animal models. While it is known that these organisms can initiate colitis development, the location and spatial distribution of these bacteria within the intestinal tract is currently unknown. In this study, we developed and optimized fluorescence in situ hybridization (FISH) probes specifically for Helicobacter species. Materials and Methods., Based on 16S-RNA gene alignments, two probes specific for the entire family Helicobacteraceae and two probes specific for Helicobacter ganmani and Helicobacter hepaticus were designed. Evaluation of these probes was determined using ATCC reference strains and cecum samples from ten IL-10 knockout mice. The presence of Helicobacter species was determined using FISH and verified using PCR-DGGE and microscopic examination of silver stained sections. Results., Analysis of the ATCC reference strains revealed that the probes HEL274/HEL717 were specific for the family Helicobacteraceae, while HEP642 was specific for H. hepaticus and GAN1237 for H. ganmani. Using these probes, a pattern of spatial localization of the two different Helicobacter species was observed in the cecum tissues of IL-10 knockout mice. This consistently showed that H. ganmani was localized to the lower regions and H. hepaticus to the mid-upper regions of the crypts. Conclusion., We have developed FISH probes specific for the family Helicobacteraceae as well as two individual Helicobacter species. This study will allow the future use of the FISH to better understand host-pathogen interactions in vitro. [source] Temporal dynamics of ipsilateral and contralateral motor activity during voluntary finger movementHUMAN BRAIN MAPPING, Issue 1 2004Ming-Xiong Huang Abstract The role of motor activity ipsilateral to movement remains a matter of debate, due in part to discrepancies among studies in the localization of this activity, when observed, and uncertainty about its time course. The present study used magnetoencephalography (MEG) to investigate the spatial localization and temporal dynamics of contralateral and ipsilateral motor activity during the preparation of unilateral finger movements. Eight right-handed normal subjects carried out self-paced finger-lifting movements with either their dominant or nondominant hand during MEG recordings. The Multi-Start Spatial Temporal multi-dipole method was used to analyze MEG responses recorded during the movement preparation and early execution stage (,800 msec to +30 msec) of movement. Three sources were localized consistently, including a source in the contralateral primary motor area (M1) and in the supplementary motor area (SMA). A third source ipsilateral to movement was located significantly anterior, inferior, and lateral to M1, in the premotor area (PMA) (Brodmann area [BA] 6). Peak latency of the SMA and the ipsilateral PMA sources significantly preceded the peak latency of the contralateral M1 source by 60 msec and 52 msec, respectively. Peak dipole strengths of both the SMA and ipsilateral PMA sources were significantly weaker than was the contralateral M1 source, but did not differ from each other. Altogether, the results indicated that the ipsilateral motor activity was associated with premotor function, rather than activity in M1. The time courses of activation in SMA and ipsilateral PMA were consistent with their purported roles in planning movements. Hum. Brain Mapp. 23:26,39, 2004. © 2004 Wiley-Liss, Inc. [source] Spatial separation of endothelial small- and intermediate-conductance calcium-activated potassium channels (KCa) and connexins: possible relationship to vasodilator function?JOURNAL OF ANATOMY, Issue 5 2006Shaun L. Sandow Abstract Activation of endothelial cell small- (S) and intermediate- (I) conductance calcium-activated potassium channels (KCa) and current or molecular transfer via myoendothelial gap junctions underlies endothelium-derived hyperpolarization leading to vasodilation. The mechanism underlying the KCa component of vasodilator activity and the characteristics of gap junctions are targets for the selective control of vascular function. In the rat mesenteric artery, where myoendothelial gap junctions and connexin (Cx) 40 are critical for the transmission of the endothelial cell hyperpolarization to the smooth muscle, SKCa and IKCa provide different facets of the endothelium-derived hyperpolarization response, being critical for the hyperpolarization and repolarization phases, respectively. The present study addressed the question of whether this functional separation of responses may be related to the spatial localization of the associated channels? The distribution of endothelial SKCa and IKCa and Cx subtype(s) were examined in the rat mesenteric artery using conventional confocal and high-resolution ultrastructural immunohistochemistry. At the internal elastic lamina,smooth muscle cell interface at internal elastic lamina holes (as potential myoendothelial gap junction sites), strong punctate IKCa, Cx37 and Cx40 expression was present. SKCa, Cx37, Cx40 and Cx43 were localized to adjacent endothelial cell gap junctions. High-resolution immunohistochemistry demonstrated IKCa and Cx37-conjugated gold to myoendothelial gap junction-associated endothelial cell projections. Clear co-localization of KCa and Cxs suggests a causal relationship between their activity and the previously described differential functional activation of SKCa and IKCa. Such precise localizations may represent a selective target for control of vasodilator function and vascular tone. [source] Alterations in intranuclear localization of Runx2 affect biological activity,,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2006Sayyed K. Zaidi The transcription factor Runx2 controls osteoblast proliferation and differentiation. Runx2 organizes and assembles gene-regulatory complexes in nuclear microenvironments where target genes are activated or suppressed in a context-dependent manner. Intranuclear localization of Runx2 is mediated by the nuclear matrix-targeting signal (NMTS), an autonomous motif with a loop (L1)-turn-loop (L2) structure that forms predicted protein,protein interaction surfaces. Here we examined the functional consequences of introducing mutations in the L1 and L2 loops of the NMTS. These mutant proteins enter the nucleus, interact with the hetero-dimeric partner Cbf,, and bind to DNA in vitro and in vivo. In addition, these mutants retain interaction with the carboxy-terminus interacting co-regulatory proteins that include TLE, YAP, and Smads. However, two critical mutations in the L2 domain of the NMTS decrease association of Runx2 with the nuclear matrix. These subnuclear targeting defective (STD) mutants of Runx2 compromise target gene activation or repression. The biological significance of these findings is reflected by decreased osteogenic differentiation of mesenchymal progenitors, concomitant with major changes in gene expression profiles, upon expression of the STD Runx2 mutant. Our results demonstrate that fidelity of temporal and spatial localization of Runx2 within the nucleus is functionally linked with biological activity. J. Cell. Physiol. 209: 935,942, 2006. © 2006 Wiley-Liss, Inc. [source] Altered distribution of mitochondria impairs calcium homeostasis in rat hippocampal neurons in cultureJOURNAL OF NEUROCHEMISTRY, Issue 1 2003Guang Jian Wang Abstract The specificity of Ca2+ signals is conferred in part by limiting changes in cytosolic Ca2+ to subcellular domains. Mitochondria play a major role in regulating Ca2+ in neurons and may participate in its spatial localization. We examined the effects of changes in the distribution of mitochondria on NMDA-induced Ca2+ increases. Hippocampal cultures were treated with the microtubule-destabilizing agent vinblastine, which caused the mitochondria to aggregate and migrate towards one side of the neuron. This treatment did not appear to decrease the energy status of mitochondria, as indicated by a normal membrane potential and pH gradient across the inner membrane. Moreover, electron microscopy showed that vinblastine treatment altered the distribution but not the ultrastructure of mitochondria. NMDA (200 µm, 1 min) evoked a greater increase in cytosolic Ca2+ in vinblastine-treated cells than in untreated cells. This increase did not result from impaired Ca2+ efflux, enhanced Ca2+ influx, opening of the mitochondrial permeability transition pore or altered function of endoplasmic reticulum Ca2+ stores. Ca2+ uptake into mitochondria was reduced by 53% in vinblastine-treated cells, as reported by mitochondrially targeted aequorin. Thus, the distribution of mitochondria maintained by microtubules is critical for buffering Ca2+ influx. A subset of mitochondria close to a Ca2+ source may preferentially regulate Ca2+ microdomains, set the threshold for Ca2+ -induced toxicity and participate in local ATP production. [source] Spatially-localized correlation of dGEMRIC-measured GAG distribution and mechanical stiffness in the human tibial plateauJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2005Joseph T. Samosky Abstract The concentration of glycosaminoglycan (GAG) in articular cartilage is known to be an important determinant of tissue mechanical properties based on numerous studies relating bulk GAG and mechanical properties. To date limited information exists regarding the relationship between GAG and mechanical properties on a spatially-localized basis in intact samples of native tissue. This relation can now be explored by using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC,a recently available non-destructive magnetic resonance imaging method for measuring glycosaminoglycan concentration) combined with non-destructive mechanical indentation testing. In this study, three tibial plateaus from patients undergoing total knee arthroplasty were imaged by dGEMRIC. At 33,44 test locations for each tibial plateau, the load response to focal indentation was measured as an index of cartilage stiffness. Overall, a high correlation was found between the dGEMRIC index (T) and local stiffness (Pearson correlation coefficients r = 0.90, 0.64, 0.81; p < 0.0001) when the GAG at each test location was averaged over a depth of tissue comparable to that affected by the indentation. When GAG was averaged over larger depths, the correlations were generally lower. In addition, the correlations improved when the central and peripheral (submeniscal) areas of the tibial plateau were analyzed separately, suggesting that a factor other than GAG concentration is also contributing to indentation stiffness. The results demonstrate the importance of MRI in yielding spatial localization of GAG concentration in the evaluation of cartilage mechanical properties when heterogeneous samples are involved and suggest the possibility that the evaluation of mechanical properties may be improved further by adding other MRI parameters sensitive to the collagen component of cartilage. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Age and gender dependence of human cardiac phosphorus metabolites determined by SLOOP 31P MR spectroscopyMAGNETIC RESONANCE IN MEDICINE, Issue 4 2006Herbert Köstler Abstract The aim of this study was to apply 31P magnetic resonance spectroscopy (MRS) using spatial localization with optimal point spread function (SLOOP) to investigate possible age and gender dependencies of the energy metabolite concentrations in the human heart. Thirty healthy volunteers (18 males and 12 females, 21,67 years old, mean = 40.7 years) were examined with the use of 31P-MRS on a 1.5 T scanner. Intra- and interobserver variability measures (determined in eight of the volunteers) were both 3.8% for phosphocreatine (PCr), and 4.7% and 8.3%, respectively, for adenosine triphosphate (ATP). High-energy phosphate (HEP) concentrations in mmol/kg wet weight were 9.7 ± 2.4 (age < 40 years, N = 16) and 7.7 ± 2.5 (age , 40 years, N = 14) for PCr, and 5.1 ± 1.0 (age < 40 years) and 4.1 ± 0.8 (age , 40 years) for ATP, respectively. Separated by gender, PCr concentrations of 9.2 ± 2.4 (men, N = 18) and 8.0 ± 2.8 (women, N = 12) and ATP concentrations of 4.9 ± 1.0 (men) and 4.2 ± 0.9 (women) were measured. A significant decrease of PCr and ATP was found for volunteers older than 40 years (P < 0.05), but the differences in metabolic concentrations between both sexes were not significant. In conclusion, age has a minor but still significant impact on cardiac energy metabolism, and no significant gender differences were detected. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Cardiac applications of EPR imagingNMR IN BIOMEDICINE, Issue 5 2004Periannan Kuppusamy Abstract This review summarizes the development and application of a variety of EPR imaging modalities including spatial, spectral,spatial (spectroscopic), gated-imaging and oxygen mapping to cardiovascular studies. It has been hypothesized that free radical metabolism, oxygenation and nitric oxide generation in biological organs such as the heart may vary over the spatially defined tissue structure. We have developed instrumentation optimized for 3D spatial and 3D or 4D spectral,spatial imaging of free radicals at 1.2 GHz. Using this instrumentation high quality 3D spectral,spatial imaging of nitroxyl (nitroxide) metabolism was performed, as well as spatially localized measurements of oxygen concentrations, based on the oxygen-dependent line-broadening of the EPR spectrum. Both exogenously infused probes and endogenous radicals were used to obtain the images. It is demonstrated that the EPR imaging is a powerful tool which can provide unique information regarding the spatial localization of free radicals, oxygen and nitric oxide in biological organs and tissues. Copyright © 2004 John Wiley & Sons, Ltd. [source] Brain GABA editing by localized in vivo1H magnetic resonance spectroscopyNMR IN BIOMEDICINE, Issue 2 2004G. Bielicki Abstract Editing of GABA by 1H MRS in a specific brain area is a unique tool for in vivo non-invasive investigation of neurotransmission disorders. Selective GABA detection is achieved using sequences based on double quantum coherence (DQC). Our pulse sequence makes accurate measurements without artefacts due to spatial localization. The sequence was tested on a phantom solution. The effect of vigabatrin, a specific inhibitor of GABA transaminase, was measured in rat brain and GABA detection was performed in vivo in monkey brain using this procedure. Rats were spilt into two groups. In the control group, the rats had access to water and, in the other group (vigabatrin, VGB, rats), animals were allowed free access to drinking water containing vigabatrin. After 3 weeks of treatment, rats were anesthetized for in vivo NMR spectroscopy investigation. At the end of the experiment, brains were quickly removed, freeze-clamped and extracted with 4% perchloric acid. One part of the acid extract was used for GABA concentrations assessment by ion exchange chromatography with ninhydrin detection. The second was used for high-resolution NMR analysis. By chromatography measurements, the GABA concentration was 1.23±0.06,,mol/g for controls, while for vigabatrin-treated rats the GABA concentration was 4.89±1.60,,mol/g. The NMR in vivo results were closely correlated with the NMR ex vivo (r=0.99, p<0.01) and chromatography results (r=0.98, p<0.01). The correlation between ex vivo results and chromatography results was also high (r=0.99, p<0.001). This pulse sequence performed GABA editing from a 376,,l voxel located on the right basal ganglia area in a non-human primate brain. This in vivo GABA editing scheme can thus be proposed for accurate measurement of brain GABA concentrations. Copyright © 2004 John Wiley & Sons, Ltd. [source] Improved spatial localization based on flow-moment-nulled and intra-voxel incoherent motion-weighted fMRINMR IN BIOMEDICINE, Issue 3 2003Allen W. Song Abstract Functional MRI signal based on the blood oxygenation level-dependent contrast can reveal brain vascular activities secondary to neuronal activation. It could, however, arise from vascular compartments of all sizes, and in particular, be largely influenced by contributions of large vein origins that are distant from the neuronal activities. Alternative contrasts can be generated based on the cerebral blood flow or volume changes that would provide complementary information to help achieve more accurate localization to the small vessel origins. Recent reports also indicated that apparent diffusion coefficient-based contrast using intravoxel incoherent motion (IVIM) weighting could be used to efficiently detect synchronized signal changes with the functional activities. It was found that this contrast has significant arterial contribution where flow changes are more dominant. In this study, a refined approach was proposed that incorporated the flow-moment-nulling (FMN) strategy to study signal changes from the brain activation. The results were then compared with those from conventional IVIM- and BOLD-weighted acquisitions. It was shown that the activated region using the new acquisition strategy had smaller spatial extent, which was contained within the activated areas from the other two methods. Based on the known characteristics of the conventional IVIM and BOLD contrasts, it was inferred that the FMN,IVIM acquisition had improved selective sensitivity towards smaller vessels where volume changes were prevalent. Therefore, such an acquisition method may provide more specific spatial localization closely coupled to the true neuronal activities. Copyright © 2003 John Wiley & Sons, Ltd. [source] CD 95 mediated apoptosis in embryogenesis: implication in tooth developmentORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 3 2006E Matalová Structured abstract Authors,,, Matalová E, ,etková J, Blackburn J, Mí,ek I, Sharpe PT Introduction,,, Understanding of apoptotic mechanisms involved in tissue shaping is of particular interest because of possible targeted modulation of the development of organ structures such as teeth. Research of CD 95 mediated apoptosis has been focused particularly on cell death in the immune system and related disorders. However, CD 95 mediated apoptosis is also involved in embryogenesis of many organs as the kidney, the lung, the intestine and tissue networks such as the nervous system. Design,,, Narrative review. Results,,, This review briefly summarizes the current knowledge of CD 95 mediated apoptosis in embryogenesis with possible implication in tooth development. CD 95 receptor and CD 95 ligand are found at early stages of tooth development. The data suggest some positive correlations with dental apoptosis distribution, particularly in the primary enamel knot where apoptosis occurs during elimination of this structure. CD 95 deficient (lpr) adult mouse tooth phenotype, however, did not show any alterations in final tooth pattern and morphology. Conclusion,,, To date studies of apoptotic machinery during tooth development show spatial localization of many of the components together with precise and localized timing of cell death. There is still much to be learned about the regulation and importance of apoptosis in tooth development. Nevertheless, the involvement of apoptotic regulatory mechanisms interplaying with other molecules participates to the cellular cross-talk in developing tissues, which opens possible targeted modulations as suggested, e.g. for future molecular dentistry. [source] Matrix-assisted laser desorption/ionization imaging mass spectrometry for direct measurement of clozapine in rat brain tissueRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2006Yunsheng Hsieh Matrix-assisted laser desorption/ionization hyphenated with quadrupole time-of-flight (QTOF) mass spectrometry (MS) has been used to directly determine the distribution of pharmaceuticals in rat brain tissue slices which might unravel their disposition for new drug development. Clozapine, an antipsychotic drug, and norclozapine were used as model compounds to investigate fundamental parameters such as matrix and solvent effects and irradiance dependence on MALDI intensity but also to address the issues with direct tissue imaging MS technique such as (1) uniform coating by the matrix, (2) linearity of MALDI signals, and (3) redistribution of surface analytes. The tissue sections were coated with various matrices on MALDI plates by airspray deposition prior to MS detection. MALDI signals of analytes were detected by monitoring the dissociation of the individual protonated molecules to their predominant MS/MS product ions. The matrices were chosen for tissue applications based on their ability to form a homogeneous coating of dense crystals and to yield greater sensitivity. Images revealing the spatial localization in tissue sections using MALDI-QTOF following a direct infusion of 3H-clozapine into rat brain were found to be in good correlation with those using a radioautographic approach. The density of clozapine and its major metabolites from whole brain homogenates was further confirmed using fast high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) procedures. Copyright © 2006 John Wiley & Sons, Ltd. [source] Wiskott,Aldrich syndrome protein and the cytoskeletal dynamics of dendritic cellsTHE JOURNAL OF PATHOLOGY, Issue 4 2004Yolanda Calle Abstract The regulated migration and spatial localization of dendritic cells in response to environmental signals are critical events during the initiation of physiological immune responses and maintenance of tolerance. Cells deficient in the Wiskott,Aldrich syndrome protein (WASP) have been used to demonstrate the importance of the dynamic remodelling of the actin-based cytoskeleton during the selective adhesion and migration of these cells. Unlike most cell types, macrophages, dendritic cells, and osteoclasts utilize a specialized adhesive array termed the podosome in order to migrate. Podosomes are composed of many of the same structural and regulatory proteins as seen in the more commonly found focal adhesion, but are unique in their requirement for WASP. Without WASP, podosomes cannot form and the affected cells are obliged to use focal adhesions for their migratory activities. Once activated by a series of upstream regulatory proteins, WASP acts as a scaffold for the binding of the potent actin nucleating protein complex known as Arp2/3. This article reviews the available evidence that suggests that failures in the regulation of the actin cytoskeleton may contribute significantly to the immunopathology of the Wiskott,Aldrich syndrome. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Magnetic force microscopy of iron oxide nanoparticles and their cellular uptakeBIOTECHNOLOGY PROGRESS, Issue 4 2009Yu Zhang Abstract Magnetic force microscopy has the capability to detect magnetic domains from a close distance, which can provide the magnetic force gradient image of the scanned samples and also simultaneously obtain atomic force microscope (AFM) topography image as well as AFM phase image. In this work, we demonstrate the use of magnetic force microscopy together with AFM topography and phase imaging for the characterization of magnetic iron oxide nanoparticles and their cellular uptake behavior with the MCF7 carcinoma breast epithelial cells. This method can provide useful information such as the magnetic responses of nanoparticles, nanoparticle spatial localization, cell morphology, and cell surface domains at the same time for better understanding magnetic nanoparticle-cell interaction. It would help to design magnetic-related new imaging, diagnostic and therapeutic methods. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||||||||