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1.

001-es BibID:	BIBFORM006041
Első szerző:	Liegler, T.
Cím:	Proximity measurements between H-2 antigens and the insulin receptor by fluorescence energy transfer : evidence that a close association does not influence insulin binding / T. Liegler, J. Szöllösi, W. Hyun, R. S. Goodenow
Dátum:	1991
Megjegyzések:	Reports based on coprecipitation experiments have suggested that major histocompatibility complex class I products are complexed with the insulin receptor on the cell surface. Using an independent method that avoids the creation of immunoprecipitation artifacts during membrane solubilization, we have studied insulin receptor-class I product associations by determining the proximity between these class I products and the insulin receptor on intact cells with the use of fluorescence energy transfer. Significant energy transfer was seen between the insulin receptor and both murine H-2K- as well as H-2D-end products, indicating close proximity (e.g., within 10 nm). This cell-surface association is not from the relatively high class I density in that no significant energy transfer was measured between H-2K- vs. H-2D-end proteins. To extend these observations, we also tested whether class I products influence insulin-receptor binding and postbinding events as a result of their physical association. Using related cell lines positive and negative for class I expression, we found no correlation between insulin-receptor density or binding affinity with H-2 product expression. The class I-null variant, however, demonstrated an increase in insulin-mediated insulin-receptor internalization to suggest that if major histocompatibility complex class I products directly affect insulin-receptor function through specific cell-surface interactions, they may do so after ligand binding.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban analysis Animal Artifacts Cell Line Cell Membrane Energy Transfer Fluorescence H-2 Antigens Haplotypes Human Insulin Kinetics Major Histocompatibility Complex metabolism methods Mice physiology Proteins Radioimmunoassay Radioligand Assay Receptor,Insulin Recombinant Proteins Spectrometry,Fluorescence Support,Non-U.S.Gov't Support,U.S.Gov't,P.H.S. Transfection
Megjelenés:	Proceedings of the National Academy of Sciences of the United States of America. - 88 : 15 (1991), p. 6755-6759. -
További szerzők:	Szöllősi János (1953-) (biofizikus) Hyun, William C. Goodenow, R. S.
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2.

001-es BibID:	BIBFORM004878
035-os BibID:	(scopus)26444586247 (wos)000232299300007
Első szerző:	Nagy Péter (biofizikus)
Cím:	Novel calibration method for flow cytometric fluorescence resonance energy transfer measurements between visible fluorescent proteins / Nagy, P., Bene, L., Hyun, W. C., Vereb, G., Braun, M., Antz, C., Paysan, J., Damjanovich, S., Park, J. W., Szollosi, J.
Dátum:	2005
ISSN:	1552-4922
Megjegyzések:	The combination of fluorescence resonance energy transfer (FRET) and flow cytometry offers a statistically firm approach to study protein associations. Fusing green fluorescent protein (GFP) to a studied protein usually does not disturb the normal function of a protein, but quantitation of FRET efficiency calculated between GFP derivatives poses a problem in flow cytometry. METHODS: We generated chimeras in which cyan fluorescent protein (CFP) was separated by amino acid linkers of different sizes from yellow fluorescent protein (YFP) and used them to calibrate the cell-by-cell flow cytometric FRET measurements carried out on two different dual-laser flow cytometers. Then, CFP-Kip1 was coexpressed in yeast cells with YFP and cyclin-dependent kinase-2 (Cdk2) and served as a positive control for FRET measurements, and CFP-Kip1 coexpressed with a random peptide fused to YFP was the negative control. RESULTS: We measured donor, direct, and sensitized acceptor fluorescence intensities and developed a novel way to calculate a factor (alpha) that characterized the fluorescence intensity of acceptor molecules relative to the same number of excited donor molecules, which is essential for quantifying FRET efficiency. This was achieved by calculating FRET efficiency in two different ways and minimizing the squared difference between the two results by changing alpha. Our method reliably detected the association of Cdk2 with its inhibitor, Kip1, whereas the nonspecific FRET efficiency between Cdk2 and a random peptide was negligible. We identified and sorted subpopulations of yeast cells showing interaction between the studied proteins. CONCLUSIONS: We have described a straightforward novel calibration method to accurately quantitate FRET efficiency between GFP derivatives in flow cytometry
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk analysis Biophysics Calibration Cells chemistry Cyclin-Dependent Kinase 2 Cyclin-Dependent Kinase Inhibitor p27 Energy Transfer Flow Cytometry Fluorescence Fluorescence Resonance Energy Transfer Hungary metabolism methods Protein Binding Proteins Research Saccharomyces cerevisiae Saccharomyces cerevisiae Proteins Support
Megjelenés:	Cytometry. Part A. - 67 : 2 (2005), p. 86-96. -
További szerzők:	Bene László (1963-) (biofizikus) Hyun, William C. Vereb György (1965-) (biofizikus, orvos) Braun, Manuel Antz, Christof Paysan, Jacques Damjanovich Sándor (1936-2017) (biofizikus) Park, John W. Szöllősi János (1953-) (biofizikus)
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3.

001-es BibID:	BIBFORM004634
035-os BibID:	(scopus)0032101894 (wos)000073937700007
Első szerző:	Nagy Péter (biofizikus)
Cím:	EGF-induced redistribution of erbB2 on breast tumor cells : flow and image cytometric energy transfer measurements / Nagy, P., Bene, L., Balazs, M., Hyun, W. C., Lockett, S. J., Chiang, N. Y., Waldman, F., Feuerstein, B. G., Damjanovich, S., Szollosi, J.
Dátum:	1998
Megjegyzések:	erbB2, a member of the epidermal growth factor (EGF) receptor-type tyrosine kinase receptor family, is overexpressed in breast carcinomas with poor prognosis. We examined the cell surface association of this receptor with itself and with other cell surface proteins by the Forster-type fluorescence resonance energy transfer using whole antibodies and Fab fragments. We found that erbB2 molecules homoassociate in unstimulated SK-BR-3, BT474 and BT474-M (a metastatic version of the parent BT474 line) breast tumor cells, and that the interaction was enhanced by EGF treatment in suspensions of SK-BR-3 and BT474-M cells. BT474 cells (with low EGF receptor expression) and attached SK-BR-3 cells do not respond to EGF. Image microscopic energy transfer measurements found considerable pixel-by-pixel heterogeneity in the homoassociation state of erbB2. In accordance with the EGF-induced redistribution of erbB2, EGF receptor was found to be in close proximity to erbB2 in FRET measurements. By labeling different epitopes on erbB2 and the lipid bilayer, we were able to prepare an epitope map of erbB2 molecule. Our data suggest the existence of dynamic cell surface patterns of erbB2 and point to functions fulfilled by these molecular complexes.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk analysis biosynthesis Breast Neoplasms Carcinoma Cell Membrane chemistry drug effects Energy Transfer Epidermal Growth Factor Female Flow Cytometry Fluorescence Human Hungary metabolism methods Models Molecular pharmacology Receptor erbB-2 Receptors Transferrin Support Non-U.S.Gov't Tumor Cells,Cultured Squamous Cell ultrastructure
Megjelenés:	Cytometry. - 32 : 2 (1998), p. 120-131. -
További szerzők:	Bene László (1963-) (biofizikus) Balázs Margit (1952-) (sejtbiológus, molekuláris genetikus) Hyun, William C. Lockett, Steven J. Chiang, Nancy Y. Waldman, Frederick Feuerstein, Burt G. Damjanovich Sándor (1936-2017) (biofizikus) Szöllősi János (1953-) (biofizikus)
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4.

001-es BibID:	BIBFORM006049
Első szerző:	Pershadsingh, Harrihar A.
Cím:	Effects of ciglitazone on blood pressure and intracellular calcium metabolism / Pershadsingh, H. A., Szollosi, J., Benson, S., Hyun, W. C., Feuerstein, B. G., Kurtz, T. W.
Dátum:	1993
Megjegyzések:	Ciglitazone is the prototype of the thiazolidinedione class of compounds currently being developed for the treatment of insulin resistance and non-insulin-dependent diabetes. The effects of thiazolidinediones on blood pressure and cell calcium metabolism are not well defined. In the obese Zucker rat, a widely studied model of insulin resistance associated with mild hypertension, we investigated the effects of ciglitazone on plasma insulin levels and mean arterial pressure. We also evaluated the effects of ciglitazone on the changes in cytosolic calcium induced by platelet-derived growth factor in A172 human glioblastoma cells and rat A10 vascular smooth muscle cells. Oral administration of ciglitazone, approximately 45 mg/kg per day for 4 weeks, induced significant reductions in plasma insulin levels (p < 0.001) and blood pressure (p < 0.05). Ciglitazone was also found to significantly attenuate the capacity of platelet-derived growth factor BB homodimer to induce sustained increases in intracellular free calcium. These findings suggest that thiazolidinediones may offer a novel pharmacological approach to the treatment of hypertension, and raise the possibility that these compounds may affect blood pressure not only by affecting insulin metabolism but also by modifying the cell calcium response to pressor agents, growth factors, or both.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Animal blood Blood Pressure Calcium drug effects Female Glioblastoma Human Insulin Intracellular Membranes metabolism Obesity pharmacology Platelet-Derived Growth Factor Rats Rats,Zucker Signal Transduction Thiazoles Tumor Cells,Cultured
Megjelenés:	Hypertension. - 21 : 6 Pt 2 (1993), p. 1020-1023. -
További szerzők:	Szöllősi János (1953-) (biofizikus) Benson, Steve Hyun, William C. Feuerstein, Burt G. Kurtz, Theodore W.
Internet cím:	elektronikus változat
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5.

001-es BibID:	BIBFORM004638
Első szerző:	Sullam, Paul M.
Cím:	Physical proximity and functional interplay of the glycoprotein Ib-IX-V complex and the Fc receptor FcgammaRIIA on the platelet plasma membrane / Sullam, P. M., Hyun, W. C., Szollosi, J., Dong, J., Foss, W. M., Lopez, J. A.
Dátum:	1998
ISSN:	021-9258
Megjegyzések:	Although the glycoprotein (GP) Ib-IX-V complex and FcgammaRIIA are distinct platelet membrane receptors, previous studies have suggested that these structures may be co-localized. To determine more directly the proximity of GP Ib-IX-V and FcgammaRIIA, we assessed the effects of anti-GP Ibalpha monoclonal antibodies on FcgammaRIIA-mediated platelet aggregation and on the direct binding of polymeric IgG to human platelets. In addition, we directly examined the proximity of FcgammaRII and GP Ib-IX-V using flow cytometric fluorescence energy transfer and immunoprecipitation studies. Preincubation of platelets with either of two monoclonal antibodies (AN51 or SZ2) directed against GP Ibalpha completely blocked platelet aggregation by polymeric IgG. Similarly, these antibodies totally inhibited platelet aggregation by two strains of viridans group streptococci known to induce aggregation via FcgammaRIIA. In addition, AN51 and SZ2 significantly reduced the binding of polymeric IgG to washed fixed platelets. When assessed by flow cytometry, significant levels of bidirectional energy transfer were detected between FcgammaRIIA and GP Ibalpha, indicating a physical proximity of less than 10 nm between these receptors. This energy transfer was not due to high receptor density, because no homoassociative energy transfer was seen. Moreover, immunoprecipitation of FcgammaRIIA from platelet lysates also co-precipitated GP Ibalpha. These results indicate that GP Ibalpha and FcgammaRIIA are co-localized on the platelet membrane and that this association is not random
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Antibodies Antibodies, Monoclonal Antigens, CD blood Blood Coagulation Factors Blood Platelets Cell Membrane drug effects Dyes Energy Transfer Flow Cytometry Fluorescence Fluorescent Dyes Human Immunoglobulin G immunology isolation and purification metabolism pharmacology Platelet Aggregation Platelet Glycoprotein GPIb-IX Complex Precipitin Tests Protein Binding Receptors, IgG Support, Non-U.S.Gov't Support, U.S.Gov't, P.H.S. ultrastructure
Megjelenés:	The Journal of Biological Chemistry. - 273 : 9 (1998), p. 5331-5336. -
További szerzők:	Hyun, William C. Szöllősi János (1953-) (biofizikus) Dong, Jing-fei Foss, Wendy M. Lopez, José A.
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6.

001-es BibID:	BIBFORM006053
Első szerző:	Szöllősi János (biofizikus)
Cím:	Attachment of A172 human glioblastoma cells affects calcium signalling : a comparison of image cytometry, flow cytometry, and spectrofluorometry / Szollosi, J., Feuerstein, B. G., Hyun, W. C., Das, M. K., Marton, L. J.
Dátum:	1991
Megjegyzések:	The intracellular free calcium concentration ([Ca2+]i) of indo-1 loaded A172 human glioblastoma cells stimulated by platelet-derived growth factor (PDGF) was studied in cell suspensions by flow cytometry and spectrofluorometry and in confluent monolayers by laser image cytometry and spectrofluorometry. With all three techniques, the percentage of responsive cells, peak [Ca2+]i, and the duration of response were directly related, and the delay time was inversely related to PDGF dose. The maximum response occurred at a PDGF concentration of about 20 ng/ml. Basal and peak [Ca2+]i did not differ significantly from method to method even though different calibration procedures were used. Cells in suspension monitored by both spectrofluorometry and flow cytometry displayed significantly shorter calcium responses than attached cells. This did not appear to be a direct effect of trypsinization. Spectral analysis of indo-1 in cytoplasm, 40% glycerol, and aqueous solutions showed significant differences in the isosbestic point and quantum efficiency. Calibration of [Ca2+]i with spectrofluorometry is more accurate using the ratio of fluorescence intensities than the fluorescence intensities measured at either 405 or 485 nm.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk analysis Calcium Cell Separation Chelating Agents Comparative Study Cytoplasm drug therapy Dyes Flow Cytometry Fluorescence Fluorescent Dyes Glioblastoma Glioma Glycerol Human Image Cytometry Indoles metabolism pharmacology Platelet-Derived Growth Factor Spectrometry,Fluorescence Support,Non-U.S.Gov't Support,U.S.Gov't,P.H.S. Tumor Cells,Cultured
Megjelenés:	Cytometry. - 12 : 8 (1991), p. 707-716. -
További szerzők:	Feuerstein, Burt G. Hyun, William C. Das, M. K. Marton, Laurence J.
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7.

001-es BibID:	BIBFORM006077
Első szerző:	Vereb György (biofizikus, orvos)
Cím:	Depletion of intracellular calcium stores facilitates the influx of extracellular calcium in platelet derived growth factor stimulated A172 glioblastoma cells / Vereb, G., Jr., Szollosi, J., Matyus, L., Balazs, M., Hyun, W. C., Feuerstein, B. G.
Dátum:	1996
Megjegyzések:	Calcium signaling in non-excitable cells is the consequence of calcium release from intracellular stores, at times followed by entry of extracellular calcium through the plasma membrane. To study whether entry of calcium depends upon the level of saturation of intracellular stores, we measured calcium channel opening in the plasma membrane of single confluent A172 glioblastoma cells stimulated with platelet derived growth factor (PDGF) and/or bradykinin (BK). We monitored the entry of extracellular calcium by measuring manganese quenching of Indo-1 fluorescence. PDGF raised intracellular calcium concentration ([Ca2+]i) after a dose-dependent delay (tdel) and then opened calcium channels after a dose-independent delay (tch). At higher doses (> 3 nM), BK increased [Ca2+]i after a tdel approximately 0 s, and tch decreased inversely with both dose and peak [Ca2+]i. Experiments with thapsigargin (TG), BK, and PDGF indicated that BK and PDGF share intracellular Ca2+ pools that are sensitive to TG. When these stores were depleted by treatment with BK and intracellular BAPTA, tdel did not change, but tch fell to almost 0 s in PDGF stimulated cells, indicating that depletion of calcium stores affects calcium channel opening in the plasma membrane. Our data support the capacitative model for calcium channel opening and the steady-state model describing quantal Ca2+ release from intracellular stores.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk antagonists and inhibitors Biophysics Bradykinin Ca(2+)-Transporting ATPase Calcium Calcium Channel Blockers Calcium Channels Calcium Signaling Dose-Response Relationship,Drug drug effects Fluorescence Glioblastoma Human Hungary Lanthanum Manganese metabolism Neuroglia pharmacology Platelet-Derived Growth Factor Signal Transduction Support, Non-U.S. Gov't Support, U.S.Gov't, Non-P.H.S. Support, U.S.Gov't, P.H.S. Terpenes Thapsigargin Tumor Cells,Cultured
Megjelenés:	Cytometry. - 24 : 1 (1996), p. 64-73. -
További szerzők:	Szöllősi János (1953-) (biofizikus) Mátyus László (1956-) (biofizikus) Balázs Margit (1952-) (sejtbiológus, molekuláris genetikus) Hyun, William C. Feuerstein, Burt G.
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változa
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8.

001-es BibID:	BIBFORM004890
035-os BibID:	(scopus)26444597596 (wos)000232299300017
Első szerző:	Vereb György (biofizikus, orvos)
Cím:	Biphasic calcium response of platelet-derived growth factor stimulated glioblastoma cells is a function of cell confluence / Vereb, G., Feuerstein, B. G., Hyun, W. C., Fulwyler, M. J., Balazs, M., Szollosi, J.
Dátum:	2005
ISSN:	1552-4922
Megjegyzések:	Previous reports have linked the spiking or two-phased character of calcium transients evoked by platelet-derived growth factor (PDGF) to the position of cells in the cell cycle without regard to cell-cell contact and communication. Because cell confluence can regulate growth factor receptor expression and dephosphorylation, we investigated the effect of cell culture confluence and cell cycle on calcium responses of PDGF-BB-stimulated A172 glioblastoma cells. METHODS: Digital imaging cytometry was used to correlate the peak and duration of calcium response with bromodeoxyuridine positivity and DNA content and with culture confluence on a cell-by-cell basis. RESULTS: In serum-starved cultures, complete two-phase calcium signals and shorter, lower spikes occurred independent of cell cycle phase. However, the confluence of cell culture seemed essential for inducing a complete response because cells in sparse cultures exhibited mostly short spikes with lower peaks or no transients at all. CONCLUSION: Because cell confluence, by virtue of cell-cell contacts, is assumed to be an important regulator of proliferation, one is tempted to speculate that in transformed cells the ability to produce stronger growth signals upon reaching confluence and facing contact inhibition could provide a proliferative advantage.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk analysis Biophysics Bromodeoxyuridine Calcium Calcium Signaling Cell Adhesion Cell Culture Cell Cycle Cells Cells,Cultured Dna drug effects genetics Glioblastoma Hungary metabolism methods pathology pharmacology Platelet-Derived Growth Factor Research Spectrometry,Fluorescence Support
Megjelenés:	Cytometry. Part A. - 67 : 2 (2005), p. 172-179. -
További szerzők:	Feuerstein, Burt G. Hyun, William C. Fulwyler, Mack J. Balázs Margit (1952-) (sejtbiológus, molekuláris genetikus) Szöllősi János (1953-) (biofizikus)
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