ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Receptor specific for certain nucleotides stimulates inositol phosphate metabolism and Ca2+ fluxes in A431 cells (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 606-617 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have recently reported that extracellular ATP induces a transient rise in cytosolic free Ca2+([Ca2+]i) in individual human epidermoid carcinoma A431 cells (Gonzalez et al: Journal of Cellular Physiology 135:269-276, 1988). We have now studied nucleotide specificity and desensitization for several early responses. Extracellular ATP (5-100 μM) caused the rapid formation of inositol trisphosphate and later its metabolites, inositol bisphosphate and inositol monophosphate. ATP also induced the efflux of 45Ca2+ from pre-loaded cells. In addition, an increase in the rate of influx of 45Ca2+ stimulated by extracellular ATP was detected. Based on measurements of 45Ca2+ efflux and influx, desensitization studies, and chlortetracycline fluorimetry, we conclude that ATP mobilizes Ca2+ from internal stores and also stimulates entry across the plasma membrane. These effects were also displayed by UTP and to a lesser extent by ITP, while other nucleoside triphosphates as well as ADP, AMP, and adenosine, were inactive. Furthermore, desensitization of the response to ATP and UTP was seen after prolonged exposure to either nucleotide. This was specific for the nucleotide receptor since a response to bradykinin was not affected by the ATP pretreatment, although pretreatment with phorbol ester inhibited responses to both the nucleotides and bradykinin. Quantitative data on rate of recovery from the desensitized state and the response of desensitized cells to greatly elevated levels of ATP are presented. Extracellular ATP stimulated another early change previously reported for epidermal growth factor, namely, the phosphorylation of an 81-kDa cytoskeletal protein. The stimulation of these events involves an ATP receptor whose properties differ from other ATP receptors that have been described.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041410320
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Secretory character of a group of isoproterenol-induced polypeptides in mouse parotid glands (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 660-666 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secretory nature of the isoproterenol-induced mouse parotid polypeptides C, D, E, F, and G (molecular weights 64,000, 61,000, 51,500, 38,000, and 37,000, respectively) is documented. Polypeptides C, D, E, F, and G, accumulated in response to successive daily stimulations with isoproterenol, were detected in a fraction enriched in hypertrophic parotid acinar cells. These cells, characterized by an increased content of cytoplasmic granules, maintain a secretory responsiveness to isoproterenol, which has been evidenced by light microscopy, enzymatic analysis, and unidimensional SDS-polyacrylamide gel electrophoresis. Thus, a parallelism in the loss and recovery of both secretory granules, α-amylase and polypeptides C, D, E, F, and G, was observed. Moreover, after secretion stimulation, polypeptides C, D, E, F, and G were detected in the fluid collected directly from parotid gland cannulation. Given the secretory character of polypeptides C, D, E, F, and G, mechanisms explaining both their progressive accumulation along the chronic administration of isoproterenol, as well as their progressive disappearance observed after suspending that treatment, are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041410326
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Studies on the increase in cytosolic free calcium induced by epidermal growth factor, serum, and nucleotides in individual A431 cells (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 269-276 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The response of cytosolic calcium [Ca2+]i to epidermal growth factor (EGF), fetal calf serum, and nucleotides was determined in individual A431 cells, using the fluorescent probe fura-2 and quantitative digital video fluorescence microscopy. In the presence of 1 mM external Ca2+, EGF caused a rapid rise in [Ca2+]i, followed by a slower and variable decrease. The cells responded after a lag that varied from 10 to 30 seconds, and there was considerable cell-to-cell variation in extent of the rise in [Ca2+]i. A second challenge with EGF gave negative results. No response was obtained in nominally Ca2+-free medium supplemented with 100 μM EGTA. Somewhat similar results were obtained with fetal calf serum except that a rise in [Ca2+]i was observed both in the presence and absence of external Ca2+. The A431 cells responded to external ATP with a rise in [Ca2+]i in less than 10 seconds, both in Ca2+-containing and Ca2+-free media. A coverslip with attached cells was mounted on a small chamber, allowing complete change of medium in 2 seconds. A nearly full response was obtained with only 10 seconds of contact of cells with ATP-containing medium. After washing out ATP, there was little or no response to a second addition given 100 seconds after the first. However, a second response was obtained when the concentration of agonist was increased 10-20-fold. These data favor the idea of receptor desensitization. Both homologous and heterologous receptor desensitization was observed. A transient rise in [Ca2+]i was also noted with UTP, while ITP and CTP were inactive.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041350214
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Immunochemical localization of epididymal protein DE on rat spermatozoa: Its fate after induced acrosome reaction (1986)
    New York, NY : Wiley-Blackwell
    Gamete Research 15 (1986), S. 247-257 
    Details
    ISSN: 0148-7280
    Keywords: epididymal proteins ; capacitation ; gamete interaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The localization of rat epididymal protein DE on cauda epididymis spermatozoa was studied with a specific antibody and the peroxidase antiperoxidase (PAP) immunocyto-chemical reaction. At the light microscopic level, all spermatozoa appeared to be labeled over the dorsal portion of the head, whereas tails were negative. This observation was confirmed using scanning electron microscopy. A large number of particles were seen on the external surface of the plasma membrane covering the acrosomal region and a smaller number on the postacrosomal portion. Flagella appeared free of particles. Sperm suspensions were incubated in conditions that induce capacitation and the acrosome reaction, and, in this instance, the permanence of protein DE on the vesicles and the postacrosomal region of the membrane were observed. The localization of this epididymal protein on the sperm surface is compatible with a role in the gamete interaction process.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120150306
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Towards the genetic dissection of mitosis in Drosophila (1987)
    New York, NY : Wiley-Blackwell
    BioEssays 7 (1987), S. 204-210 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell division is an universal process the aim of which is the equitable distribution of subcellular organelles from single cells to their daughters. The extraordinary accuracy with which the genetic material is partitioned requires a complex machinery involving many gene products. Genetic approaches can be used to identify the relevant components and processes, and mutational analysis of loci essential for cell division has been carried out in several eukaryotes, in particular fungi and mammalian cells in culture. Recently, this type of analysis has been extended to Drosophila, an ideal eukaryote for genetic studies. We will review here the genetic dissection of mitosis in Drosophila melanogaster, discussing recent findings of interest and the methodological problems that have been encountered.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950070504
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Permeabilization of transformed mouse fibroblasts by 3′-O-(4-benzoyl)benzoyl adenosine 5′-triphosphate and the desensitization of the process (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 139 (1989), S. 109-115 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A photoreactive analogue of ATP, 3′-O-(4-benzoyl)benzoyl adenosine 5′-triphosphate (BzATP) altered the plasma membrane permeability of transformed 3T6 mouse fibroblasts to normally impermeant molecules as previously reported for ATP, but at lower concentrations. BzATP-induced permeabilization was modulated by pH, temperature, and the ionic composition of the medium similar to the permeabilizing effects of ATP. Conditions known to enhance ATP-induced permeabilization, such as treatment with the mitochondrial uncoupler carbonyl cyanide-m-chlorophenylhydrazone (CCCP) or the Ca2+-calmodulin antagonist trifluoperazine also enhanced BzATP-induced permeabilization. Conditions inhibitory to ATP-induced permeabilization, including chloride replacement or treatment with furosemide or dithiothreitol (DTT), inhibited permeabilization induced by BzATP. The ionic strength of the medium modulated the responsiveness of the cells to ATP and BzATP; a decrease in the ionic strength below isotonicity increased the sensitivity of the cells to the nucleotides, whereas an increase in ionic strength above isotonicity inhibited permeabilization. Prolonged exposure to ATP under non-permeabilizing conditions caused the cells to become insensitive to ATP and BzATP. The densensitization phenomenon provides support for the theory that the permeabilization process is mediated by a receptor for ATP.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041390116
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Off-center spherical model for dosimetry calculations in chick brain tissue (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 7 (1986), S. 209-221 
    Details
    ISSN: 0197-8462
    Keywords: brain tissue ; radiofrequency ; radiation ; dosimetry ; calcium ions ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: This paper presents calculations for the electric field and absorbed power density distribution in chick brain tissue inside a test tube, using an off-center spherical model. It is shown that the off-center spherical model overcomes many of the limitations of the concentric spherical model, and permits a more realistic modeling of the brain tissue as it sits in the bottom of the test tube surrounded by buffer solution. The effect of the unequal amount of buffer solution above the upper and below the lower surfaces of the brain is analyzed. The field distribution is obtained in terms of a rapidly converging series of zonal harmonics. A method that permits the expansion of spherical harmonics about an off-center origin in terms of spherical harmonics at the origin is developed to calculate in closed form the electric field distribution. Numerical results are presented for the absorbed power density distribution at a carrier frequency of 147 MHz. It is shown that the absorbed power density increases toward the bottom of the brain surface. Scaling relations are developed by keeping the electric field intensity in the brain tissue the same at two different frequencies. Scaling relations inside, as well as outside, the brain surface are given. The scaling relation distribution is calculated as a function of position, and compared to the scaling relations obtained in the concentric spherical model. It is shown that the off-center spherical model yields scaling ratios in the brain tissue that lie between the extreme values predicted by the concentric and isolated spherical models.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250070210
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Differential morphometric values induced in Golgi apparatus of higher plant cells by aldehyde and permanganate fixation (1989)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 11 (1989), S. 1-8 
    Details
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Fixation methods ; Golgi apparatus morphometry ; Onion roots ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In order to determine the best conditions to carry out quantitative ultrastructural studies in plant specimens, five different fixation techniques, including some of the most reported electron microscopy fixatives (glutaraldehyde-paraformaldehyde, osmium tetroxide, potassium permanganate), were assayed in onion root meristems to check their ability to induce morphometric changes in Golgi apparatus ultrastructure. Although the parameters evaluated showed in all cases the same tendency, values obtained after permanganate fixation were always higher than those found after aldehyde techniques (especially aldehyde-osmium). Aldehyde followed by osmium fixation appears as the most indicated fixation method when accurate quantitative ultrastructural studies are to be developed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060110102
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...