43 research outputs found

    Modification of fluid lipid and mobile protein fractions of reticulocyte plasma membranes affects agonist-stimulated adenylate cyclase. Application of the percolation theory

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    AbstractThe technique of fluorescence recovery after photobleaching was used to measure the lateral mobility of membrane integral proteins in reticulocyte plasma membranes which were treated to modify the ‘fluid’ lipid or immobilized protein fractions, hence increasing the relative prevalence of obstacles to protein lateral motion. This was achieved by either: (1) treating the plasma membranes with phospholipase A2 followed by extraction of the hydrolysis products using fatty-acid-free bovine serum albumin, resulting in a decrease in the membrane ‘fluid’ lipid portion; or (2) preincubating the plasma membranes with polylysines, resulting in plasma membrane protein aggregation and immobilization. As the prevalence of obstacles to lateral motion increased in plasma membranes through the treatments described above, the mobility of the membrane integral proteins diminished. Experimental results for the dependence of protein mobility on the prevalence of obstacles to lateral motion were compared to theoretical data in order to verify the applicability of the percolation theory to reticulocyte plasma membranes. The influence of a decrease in the ‘fluid’ lipid and an increase in the immobilized membrane protein fractions upon the hormone-stimulated adenylate cyclase activity has been studied as well. As the ‘solid’ lipid and immobilized membrane protein fractions decreased, both the hormone-stimulated adenylate cyclase activity and the fraction of β-adrenergic receptors with high affinity to hormone diminished. It was shown that this correlation can be caused by a decrease in membrane fraction accessible to the movement of the interacting proteins of the adenylate cyclase complex. Hormonal stimulation of adenylate cyclase is discussed in terms of the percolation theory

    Modular nanotransporters: a multipurpose in vivo working platform for targeted drug delivery

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    Tatiana A Slastnikova1,2, Andrey A Rosenkranz1,2, Pavel V Gulak1, Raymond M Schiffelers3, Tatiana N Lupanova1,4, Yuri V Khramtsov1, Michael R Zalutsky5, Alexander S Sobolev1,21Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Moscow, Russia; 2Department of Biophysics, Biological Faculty, Moscow State University, Vorobyevy Gory, Moscow, Russia; 3Laboratory for Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, the Netherlands; 4Department of Bioengineering, Biological Faculty, Moscow State University, Vorobyevy Gory, Moscow, Russia; 5Department of Radiology, Duke University Medical Center, Durham, NC, USABackground: Modular nanotransporters (MNT) are recombinant multifunctional polypeptides created to exploit a cascade of cellular processes, initiated with membrane receptor recognition to deliver selective short-range and highly cytotoxic therapeutics to the cell nucleus. This research was designed for in vivo concept testing for this drug delivery platform using two modular nanotransporters, one targeted to the α-melanocyte-stimulating hormone (αMSH) receptor overexpressed on melanoma cells and the other to the epidermal growth factor (EGF) receptor overexpressed on several cancers, including glioblastoma, and head-and-neck and breast carcinoma cells.Methods: In vivo targeting of the modular nanotransporter was determined by immunofluorescence confocal laser scanning microscopy and by accumulation of 125I-labeled modular nanotransporters. The in vivo therapeutic effects of the modular nanotransporters were assessed by photodynamic therapy studies, given that the cytotoxicity of photosensitizers is critically dependent on their delivery to the cell nucleus.Results: Immunohistochemical analyses of tumor and neighboring normal tissues of mice injected with multifunctional nanotransporters demonstrated preferential uptake in tumor tissue, particularly in cell nuclei. With 125I-labeled MNT{αMSH}, optimal tumor:muscle and tumor:skin ratios of 8:1 and 9.8:1, respectively, were observed 3 hours after injection in B16-F1 melanoma-bearing mice. Treatment with bacteriochlorin p-MNT{αMSH} yielded 89%–98% tumor growth inhibition and a two-fold increase in survival for mice with B16-F1 and Cloudman S91 melanomas. Likewise, treatment of A431 human epidermoid carcinoma-bearing mice with chlorin e6- MNT{EGF} resulted in 94% tumor growth inhibition compared with free chlorin e6, with 75% of animals surviving at 3 months compared with 0% and 20% for untreated and free chlorin e6-treated groups, respectively.Conclusion: The multifunctional nanotransporter approach provides a new in vivo functional platform for drug development that could, in principle, be applicable to any combination of cell surface receptor and agent (photosensitizers, oligonucleotides, radionuclides) requiring nuclear delivery to achieve maximum effectiveness.Keywords: drug delivery, nanobiotechnology, nanomedicine, cancer therapy, photosensitizers, multifunctional nanotransporte

    The physical parameters of clumps associated with class I methanol masers

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    We present a study of the association between class I methanol masers and cold dust clumps from the ATLASGAL survey. It was found that almost 100% of class I methanol masers are associated with objects listed in the ATLASGAL compact source catalog. We find a statistically significant difference in the flux density, luminosity, number and column density and temperature distributions of ATLASGAL sources associated with 95/44 GHz methanol masers compared with those ATLASGAL sources devoid of 95 GHz methanol masers. The masers tend to arise in clumps with higher densities, luminosities and temperatures compared with both the full sample of ATLASGAL clumps, as well as the sample of ATLASGAL sources that were cross-matched with positions previously searched for methanol masers but with no detections. Comparison between the peak position of ATLASGAL clumps and the interferometric positions of the associated class I and II methanol masers reveals that class I masers are generally located at larger physical distances from the peak submillimetre emission than class II masers. We conclude that the tight association between ATLASGAL sources and class I methanol masers may be used as a link toward understanding the conditions of the pumping of these masers and evolutionary stages at which they appear

    Molecular beam epitaxy of metamorphic buffer for InGaAs/InP photodetectors with high photosensitivity in the range of 2.2–2.6 um

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    The present work is concerned with finding optimal technological conditions for the synthesis of heterostructures with a metamorphic buffer for InGaAs/InP photodetectors in the wavelength range of 2.2–2.6 um using molecular beam epitaxy. Three choices of buffer structure differing in design and growth parameters were proposed. The internal structure of the grown samples was investigated by X-ray diffraction and transmission electron microscopy. Experimental data analysis has shown that the greatest degree of elastic strain relaxation in the InGaAs active layer was achieved in the sample where the metamorphic buffer formation ended with a consecutive increase and decrease in temperature. The said buffer also had InAs/InAlAs superlattice inserts. The dislocation density in this sample turned out to be minimal out of three, which allowed us to conclude that the described heterostructure configuration appears to be the most appropriate for manufacturing of short wavelength infrared range pin-photodetectors with high photosensitivity

    Antitumor Activity of Auger Electron Emitter 111In Delivered by Modular Nanotransporter for Treatment of Bladder Cancer With EGFR Overexpression

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    Gamma-ray emitting 111In, which is extensively used for imaging, is also a source of short-range Auger electrons (AE). While exhibiting negligible effect outside cells, these AE become highly toxic near DNA within the cell nucleus. Therefore, these radionuclides can be used as a therapeutic anticancer agent if delivered precisely into the nuclei of tumor target cells. Modular nanotransporters (MNTs) designed to provide receptor-targeted delivery of short-range therapeutic cargoes into the nuclei of target cells are perspective candidates for specific intracellular delivery of AE emitters. The objective of this study was to evaluate the in vitro and in vivo efficacy of 111In attached MNTs to kill human bladder cancer cells overexpressing epidermal growth factor receptor (EGFR). The cytotoxicity of 111In delivered by the EGFR-targeted MNT (111In-MNT) was greatly enhanced on EJ-, HT-1376-, and 5637-expressing EGFR bladder cancer cell lines compared with 111In non-targeted control. In vivo microSPECT/CT imaging and antitumor efficacy studies revealed prolonged intratumoral retention of 111In-MNT with t½ = 4.1 ± 0.5 days as well as significant dose-dependent tumor growth delay (up to 90% growth inhibition) after local infusion of 111In-MNT in EJ xenograft-bearing mice

    Oxygen isotope heterogeneity of the mantle beneath the Canary Islands : insights from olivine phenocrysts

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    Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Contributions to Mineralogy and Petrology 162 (2011): 349-363, doi:10.1007/s00410-010-0600-5.A relatively narrow range of oxygen isotopic ratios (δ18O = 5.05.4‰) is preserved in olivine of mantle xenoliths, mid-ocean ridge (MORB) and most ocean island basalts (OIB). The values in excess of this range are generally attributed either to the presence of a recycled component in the Earth’s mantle or to shallow level contamination processes. A viable way forward to trace source heterogeneity is to find a link between chemical (elemental and isotopic) composition of the earlier crystallized mineral phases (olivine) and the composition of their parental magmas, then using them to reconstruct the composition of source region. The Canary hotspot is one of a few that contains ~1-2 Ga old recycled ocean crust that can be traced to the core-mantle boundary using seismic tomography and whose origin is attributed to the mixing of at least three main isotopically distinct mantle components i.e., HIMU, DMM and EM. This work reports ion microprobe and single crystal laser fluorination oxygen isotope data of 148 olivine grains also analyzed for major and minor elements in the same spot. The olivines are from 20 samples resembling the most primitive shield stage picrite through alkali basalt to basanite series erupted on Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro, Canary Islands, for which shallow level contamination processes were not recognized. A broad range of δ18Oolivine values from 4.6 to 6.1‰ was obtained and explained by stable, long-term oxygen isotope heterogeneity of crystal cumulates present under different volcanoes. These cumulates are thought to have crystallized from mantle derived magmas uncontaminated at crustal depth, representing oxygen isotope heterogeneity of source region. A relationship between Ni×FeO/MgO and δ18Oolivine values found in one basanitic lava erupted on El Hierro, the westernmost island of the Canary Archipelago, was used to estimate oxygen isotope compositions of partial melts presumably originated from peridotite (HIMU-type component inherited its radiogenic isotope composition from ancient, ~12 Ga, recycled ocean crust) and pyroxenite (young, <1 Ga, recycled oceanic crust preserved as eclogite with depleted MORB-type isotopic signature) components of the Canary plume. The model calculations yield 5.2 and 5.9±0.3‰ for peridotite and pyroxenite derived melts, respectively, which appeared to correspond closely to the worldwide HIMU-type OIB and upper limit N-MORB δ18O values. This difference together with the broad range of δ18O variations found in the Canarian olivines cannot be explained by thermodynamic effects of oxygen isotopic fractionation and are believed to represent true variations in the mantle, due to oceanic crust and continental lithosphere recycling.This work was supported by the CNRS “poste rouge” grant to AG, the NSF EAR-CAREER-0844772 grant to IB and the CRPG-CNRS and at its initial stage by the DFG (grant SCHM 250/64) and the Alexander von Humboldt Foundation (Wolfgang Paul Award to A.V. Sobolev who provided access to the electron microprobe at the Max Planck Institute, Mainz, Germany)

    Salivary gland immunohistochemistry vs substantia nigra sonography: comparative analysis of diagnostic significance

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    Introduction. Parkinson's disease (PD) urges for new instrumental methods of diagnosis. Transcranial sonography of the substantia nigra (SN TCS) is an established method for early PD diagnosis but its application is limited. Recently, biopsies (primarily that of salivary gland) and test for abnormal -synuclein are suggested to verify PD. Materials and methods. We assessed 12 individuals with PD, HoehnYahr 2.3 0.4. The assessments included: UPDRS, NMSQ, NMSS, RBDSQ, PDQ-8, MoCA, and HADS scoring; SN TCS; and sublingual gland immunohistochemistry for phosphorylated -synuclein (PS-129) with automated morphometric analysis. Results. Substantia nigra hyperechogenicity was shown in 75% of patients whereas biopsy revealed PS-129 in 100% of patients. Echogenic area of the substantia nigra was 0.24 [0.21; 0.3] cm2. PS-129 inclusion area varied from 28.47 [27.55; 96.26] to 238.77 [234.13; 272.49] m2, and PS-129 proportion varied from 13.4% to 93.4% of the nervous fiber area across the patients. We found relations between PS-129 and NMSQ (r = 0.8; p 0.001), NMSS (r = 0.9; p 0.001), PDQ-8 (r = 0.7; p = 0.003), UPDRS-I (r = 0.7; p = 0.009), UPDRS-II (r = 0.6; p = 0.03), and HADS (anxiety r = 0.8; p = 0.002; depression r = 0.6; p = 0.04) scores. Conclusion. The results demonstrate a higher biopsy sensitivity as compared to SN TCS. Automated morphometric analysis has been newly applied to assess PS-129 occurrence. Immunohistochemistry results are directly related to non-motor symptom severity, which may indicate high probability of PS-129 presence and diagnosis confirmation in early disease

    Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

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    We present measurements of exclusive ensuremathπ+,0 and η production in pp reactions at 1.25GeV and 2.2GeV beam kinetic energy in hadron and dielectron channels. In the case of π+ and π0 , high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance-corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of Δ (1232) and higher-lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross-sections are of special interest in the case of pp → pp η , since controversial data exist at 2.0GeV; we find \ensuremathσ=0.142±0.022 mb. Using the dielectron channels, the π0 and η Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance-corrected helicity angle distributions are found in good agreement with model predictions
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