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  • 1
    Electronic Resource
    Electronic Resource
    Effects of taxol and taxol/hyperthermia treatments on the functional polarization of cytotoxic T lymphocytes (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 24 (1993), S. 129-138 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; MTOC ; centrosome ; pericentriolar material ; cytolytic activity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Immunofluorescence staining, electron microscopy, and (51Cr) cytolytic release assays are used to investigate the effects of taxol and taxol/hyperthermia treatments on the microtubule organization and cytolytic activity of cytotoxic T lymphocytes (CTLs). A 4 h treatment of CTLs with 1 μM taxol results in an extensive reorganization of the microtubule system to form one to a few large microtubule bundles that extend from the centrosome. The Golgi apparatus is not disrupted by this treatment and remains associated with the microtubule organizing centre (MTOC). This microtubule reorganization has no effect on the ability of CTLs to orient their MTOC towards a bound target cell, nor on their cytolytic activity. In control CTLs, not treated with taxol, a mild hyperthermia treatment (42°C, 30 min) results in an aggregation of the pericentriolar material, a loss of MTOC orientation, an inhibition of cytolytic activity, and a disorganization of the microtubule system [Knox et al.: Exp. Cell Res. 194:275-283, 1991]. In contrast, in taxol-treated CTLs the stabilized microtubule bundles are unaffected by such hyperthermia treatment; however, the other effects of hyperthermia appear identical in control and taxol-treated CTLs. These results indicate that a dynamic, radially arranged microtubule array is not required for the functional polarization of CTLs and suggest that a component of the pericentriolar material may play a key role in effecting MTOC orientation. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970240206
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  • 2
    Electronic Resource
    Electronic Resource
    Light microscopic observations on the release of vesicles by isolated chromaffin cells (1984)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 297-303 
    Details
    ISSN: 0886-1544
    Keywords: exocytosis ; chromaffin cells ; vesicle release ; light microscope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured bovine adrenal medullary chromaffin cells were stimulated with the secretogogues Ba2+ or carbamyl choline plus Ca2+. With video-enhanced contrast, differential interference contrast microscopy, small vesicles were found to appear on the cell surface during stimulation. The structures were of lower refractive index than the cytoplasm, and their appearance required several tenths of a second. The vesicles are thought to correspond to omega figures seen with electron microscopy due to exocytosis. Many of the structures disappeared within a few seconds, but some appeared to coalesce into larger structures. The large structures may lead to the vacuoles that have been demonstrated to be present following stimulation. The nature of the cellular elements responsible for the vesicle which appeared on the surface was not found with either differential interference or interference reflection microscopy. The simplest explanation is that the refractive index of the elements is similar to that of the cell, and therefore the elements cannot be seen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970040407
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  • 3
    Electronic Resource
    Electronic Resource
    Slow pulsatile movements of Schwann cells in vitro: A time-lapse cinemicrographic study (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 595-603 
    Details
    ISSN: 0886-1544
    Keywords: tissue culture ; Swann cell ; pulsatile movement ; time-lapse cinemicrography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Slow pulsatile movements of Schwann cells in vitro were studied quantitatively by using time-lapse cinemicrography. Schwann cells from peripheral nerves of 3-day-old rats were cultured in serum-free medium. Most Schwann cells showed intermittent episodes of pulsatile movement; each episode consisted of one or several contractile pulses. About half of the episodes consisted of a single pulse, and episodes with more than four pulses were rare. The average episode of activity lasted 2.6 min, while the average duration of a single pulse was 1.5 min. The mean quiescent interval between episodes of activity was 3.7 min. Some cells showed no pulsatile activity. Active cells averaged 6.6 episodes/h. The fraction of time which a Schwann cell spent in pulsatile activity varied widely, with an average of 28%. Behavior of Schwann cells in HEPES-buffered Hanks saline was generally similar to that in the complete medium. Raising K+ to 40 mM or Ca++ to 10 mM did not markedly affect the time course of the pulsatile motility, although the contractions were more vigorous in the high Ca++. Pulsatile movement was reversibly inhibited by cytochalasin B and appeared to be potentiated by drugs that disrupt microtubules.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060608
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  • 4
    Electronic Resource
    Electronic Resource
    Expression and mutation of Ca2+ ATPases of the sarcoplasmic reticulum (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 26-34 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140107
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of alpha-actinin from Acanthamoeba (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 649-661 
    Details
    ISSN: 0886-1544
    Keywords: actin ; gelation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Characterization of a protein from Acanthamoeba that was originally called gelation protein [T.D. Pollard, J. Biol. Chem. 256:7666-7670, 1981] has shown that it resembles the actin filament cross-linking protein, alpha-actinin, found in other cells. It comprises about 1.5% of the total amoeba protein and can be purified by chromatography with a yield of 13%. The native protein has a molecular weight of 180,000 and consists of two polypeptides of 90,000 Da. The Stokes' radius is 8.5 nm, the intrinsic viscosity is 0.35 dl/dm, and the extinction coefficient at 280 nm is 1.8 × 105M-1·cm-1. Electron micrographs of shadowed specimens show that the molecule is a rod 48 nm long and 7 nm wide with globular domains at both ends and in the middle of the shaft. On gel electrophoresis in sodium dodecylsulfate the pure protein can run as bands with apparent molecular weights of 60,000, 90,000, 95,000, or 134,000 depending on the method of sample preparation. Rabbit antibodies to electrophoretically purified Acanthamoeba alpha-actinin polypeptides react with all of these electrophoretic variants in samples of purified protein and cell extracts. By indirect fluorescent antibody staining of fixed amoebas, alpha-actinin is distributed throughout the cytoplasmic matrix and concentrated in the hyaline cytoplasm of the cortex. The protein cross-links actin filaments in the presence and absence of Ca++. It inhibits slightly the time course of the spontaneous polymerization of actin monomers but has no effect on the critical concentration for actin polymerization even though it increases the apparent rate of elongation to a small extent. Like some other cross-linking proteins, amoeba alpha-actinin inhibits the actin-activated ATPase of muscle myosin subfragment-1. Although Acanthamoeba alpha-actinin resembles the alpha-actinin from other cells in shape and ability to cross-link actin filaments, antibodies to amoeba and smooth muscle alpha-actinins do not cross react and there are substantial differences in the amino acid compositions and molecular dimensions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060613
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  • 6
    Electronic Resource
    Electronic Resource
    Actin cytoskeleton of fibroblasts organizes surface proteoglycans that bind basic fibroblast growth factor and lipoprotein lipase (1995)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 30 (1995), S. 89-107 
    Details
    ISSN: 0886-1544
    Keywords: actin ; microfilaments ; heparan sulfate proteoglycans ; heparin-binding proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell surface proteoglycans participate in molecular events that regulate cell adhesion, migration, and proliferation. To investigate the organization of these molecules at the cell surface, the distribution of two well-known proteoglycan ligands has been studied. These ligands, lipoprotein lipase and basic fibroblast growth factor, showed a characteristic binding pattern consisting of highly organized parallel arrays that crossed the upper surface of human skin fibroblasts. The proteoglycan nature of the binding sites was evident from their susceptibility to heparinases, and from ligand displacement by heparin. Parallel localization of the ligands and actin, and treatment of the cells with cytochalasin, showed that the binding proteoglycans are organized by the actin cytoskeleton. The ligands induced a different behaviour of the binding sites on incubation of the cells at 37°C. Lipoprotein lipase produced a movement of the binding proteoglycans along the actin filaments towards the cell center. In contrast, after binding of basic fibroblast growth factor the binding proteoglycans remained spread over the cell surface and actin depolymerization was induced. Since an increasing number of ligands appear to depend on proteoglycans for their interactions with their high affinity receptors, distribution and movement of proteoglycans at the cell surface that is organized by the actin cytoskeleton could direct and enhance the encounters between the ligands and their specific receptors. © 1995 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970300202
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation of a monoclonal antibody to a melanoma growth-stimulatory activity released into serum-free culture medium by Hs0294 malignant melanoma cells (1987)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 34 (1987), S. 169-185 
    Details
    ISSN: 0730-2312
    Keywords: monoclonal antibody ; melanoma growth stimulatory activity ; serum free culture medium ; Hs0294 malignant melanoma cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Autostimulatory growth factors may contribute to the ability of malignant cells to escape normal growth controls. We have previously shown that Hs0294 human malignant melanoma cells release into culture medium an acid-soluble, heat-stable, trypsin-sensitive, autostimulatory monolayer mitogen which can be purified from acetic acid extracts of conditioned medium by gel filtration, reverse-phase high-performance liquid chromatography, and preparative electrophoresis. The majority of this melanoma growth-stimulatory activity (MGSA) resides in a 16-Kd moiety though bioactivity is also associated with 24-26 and 〈 14-Kd forms of MGSA (Richmond and Thomas: J Cell Physiol 129:375, 1986). In order to further characterize this growth factor, monoclonal antibodies were prepared against a partially purified preparation of the autostimulatory melanoma mitogen. Monoclonal antibody clones were selected based on supernate inhibition of 3H-thymidine incorporation in serum-free Hs0294 melanoma cultures. One of these, termed FB2AH7, slows, but does not completely block, the growth of Hs0294 cells in scrum-free medium in a dose-dependent manner. This antibody does not slow the growth of normal rat kidney fibroblasts, which neither produce nor require this mitogen, in either serum-free medium or medium containing 0.8% calf scrum. This monoclonal antibody also blocks the mitogenic effects of partially purified preparations of this melanoma growth stimulatory activity (MGSA) on both Hs0294 cells and normal rat kidney fibroblasts. The FB2AH7 antibody has been demonstrated to bind MGSA by Western blot and by immunoprecipitation procedures. Western blot analysis of reverse-phase high-performance liquid chromatography purified growth factor demonstrated that FB2AH7 antibody binds to the 16-Kd and ∼ 13-14-Kd forms of MGSA. FB2AH7 antibody can be used in immunoprecipitation experiments to bind the ∼ 13-16-Kd forms of MGSA. The specificity of the binding of FB2AH7 antibody for MGSA but not other growth factors has been demonstrated in a modified dot blot assay. These data thus support the hypothesis that MGSA is an autostimulatory melanoma mitogen distinct from other growth factors.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240340304
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  • 8
    Electronic Resource
    Electronic Resource
    Hormone-dependent processing of the avian progesterone receptor (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 103-119 
    Details
    ISSN: 0730-2312
    Keywords: progesterone receptor ; avian ; processing ; phosphorylation ; degradation ; antibody probes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Avian progesterone receptor exists as two forms, A and B, with molecular weights of 79,000 and 110,000 daltons, respectively. The origin and significance of these two forms is an area of active investigation and debate. Monoclonal antibodies produced against these two forms were used to examine receptor stability in cytosol and changes in the receptor forms induced by hormone binding.The lability of hormone binding at elevated temperatures is well documented. Analysis by Western blotting showed the receptor was stable in freshly prepared oviduct cytosol for 2 hr at 37°C, while hormone binding was lost within 30 min. However, loss of receptor through degradation was seen when cytosol was prepared from frozen tissue or when homogenization was excessive.Progesterone was injected into diethylstilbestrol-stimulated chicks to examine, in vivo, effects of hormone treatment on receptor forms in the cytosol and nuclear fractions. Progesterone treatment caused a time- and dose-dependent conversion of the A receptor to a form (A′) with a slower electrophoretic mobility. The cytosolic progesterone receptor was divided equally between the B and A forms, while the nuclear receptor was predominantly A′. The amount of nuclear receptor was consistently less than cytosolic receptor. Receptor phosphorylation was analyzed by incubating tissue minces with [32P]orthophosphate with or without progesterone followed by immune isolation of receptor forms. Progesterone treatment caused a time-dependent increase in cytosol receptor phosphorylation which was evident after 5 min of treatment. This phosphorylation was observed with both the A and B receptor forms. The results indicate that receptor phosphorylation is a very early event during progesterone action.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360202
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  • 9
    Electronic Resource
    Electronic Resource
    Estrogen pretreatment increases arachidonic acid release by bradykinin stimulated normal human osteoblast-like cells (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 60 (1996), S. 260-270 
    Details
    ISSN: 0730-2312
    Keywords: osteoporosis ; dexamethasone ; glucocorticoids ; prostaglandins ; phospholipase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Eicosanoids are multifunctional autocrine/paracrine regulators of bone that are enzymatically derived from arachidonic acid (AA). The rate-limiting step in the eicosanoid biosynthetic pathways may be the release of AA from membrane glycerophospholipids by activated phospholipases. Free AA can serve as the substrate for cyclooxygenase(s) or lipoxygenases that catalyze the commitive steps in eicosanoid synthesis; alternatively, free AA may be used in reacylation processes, resulting in its reincorporation into cellular lipids. The hormones 17β-estradiol (17β-E2), dexamethasone (a synthetic glucocorticoid), and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) have been identified as regulators of AA metabolism, at various levels, in several tissues including bone. The possibility that these osteotropic steroids modulate the availability of free AA in bone cells was studied in the human osteoblast-like (hOB) cell model system. Following a 48-h steroid pretreatment, bradykinin or the calcium ionophore A23187 were used as agonists to stimulate hOB cell release of AA. The principal findings from these investigations were that (1) 17β-E2 pretreatment potentiated the appearance of free AA following bradykinin stimulation of the cells but, did not alter their response to A23187 stimulation; (2) dexamethasone pretreatment limited bradykinin-induced increases in free AA levels but did not alter cell response to A23187 stimulation; (3) hOB cells derived from different trabecular bone compartments (manubrium of the sternum, femoral head) differed quantitatively in their responses to bradykinin stimulation of AA release; and (4) 1,25(OH)2D3 did not effect AA release stimulated by either agonist. The ability of the steroids to modulate AA release by hOB cells suggests that these hormones may indirectly mediate bone cell responses to other osteotropic hormones that act through eicosanoid-dependent processes. © 1996 Wiley-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    Cytokine regulation of adult human osteoblast-like cell prostaglandin biosynthesis (1997)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 64 (1997), S. 618-631 
    Details
    ISSN: 0730-2312
    Keywords: cyclooxygenase ; transforming growth factor-β1 ; tumor necrosis factor-α ; interleukin-1β ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Prostaglandin (PG) biosynthesis by cytokine stimulated normal adult human osteoblast-like (hOB) cells was evaluated by thin layer chromatography, high performance liquid chromatography, and specific immunoassays. PGE2 was the predominant PG formed under all incubation conditions tested. Control samples produced measurable amounts of PGE2, and the measured level of this metabolite increased by 22-fold (from 7 to 152 ng/ml) following a 20 h treatment with the combination of TGFβ and tumor necrosis factor-α(TNF). The production of 6-keto-PGF1α (the stable metabolite of prostacyclin) and of PGF2α were each increased by about five-fold (from about 0.5 to 2.5 ng/ml) in samples treated with the cytokines. Thus, TGFβ and TNF exerted a regulation of hOB cell PG biosynthesis that was principally directed towards an increased PGE2 biosynthesis, with lesser effects on the production of other PG metabolites. COX-2 mRNA levels were increased within 2 h of cytokine stimulation, reached a maximum at 6-12 h, and levels had appreciably diminished by 24 h after treatment. Both TGFβ and TNF could independently increase COX-2 mRNA levels and PG biosynthesis. However, the increased production of PGE2 resulting from TNF stimulation was blocked by the addition of an interleukin-1β (IL-1β) neutralizing antibody, suggesting that TNF regulation of hOB cell PG synthesis was secondary to its capacity to increase hOB cell IL-1β production. TGFβ regulation of PG production was not affected by the addition of the neutralizing antibody. These studies support the proposition that PGs can be important autocrine/paracrine mediators of bone biology, whose production by hOB cells is responsively regulated by osteotropic cytokines. J. Cell. Biochem. 64:618-631. © 1997 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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