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  • Humans  (13)
  • Avionics and Aircraft Instrumentation  (10)
  • Life and Medical Sciences
  • 2005-2009  (15)
  • 2000-2004  (4)
  • 1995-1999  (4)
  • 1990-1994  (7)
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  • 1
    ISSN: 1040-452X
    Schlagwort(e): Sperm signal transduction ; Br-A23187 ; Acrosomal exocytosis ; Sperm G1 protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: The fluorescent calcium indicator, fluo-3, was loaded as the membrane permeant tetraacetoxymethyl (AM) ester into cauda epididymal mouse sperm at 25°C for 20 min in the absence of bovine serum albumin (BSA) and presence of the dispersant, Pluronic F-127. Excess indicator was removed by two centrifugation washes at 100g for 10 min, a procedure that did not impair sperm motility. Upon resuspension in medium containing 20 mg/ml BSA to promote capacitation, the sperm cells exhibited readily detectable fluorescence uniformly distributed in the cytoplasm. Cell fluorescence was stable over the time of the experiments and was responsive to changes in intracellular calcium concentration, [Ca2+]j. Initial [Ca2+]j was 231 ± 58 nM (±SE, n = 43). Addition of heat-solubilized mouse zonae pellucidae to capacitated sperm increased [Ca2+]j by 106 ± 19 nM (±SE, n = 18), the higher steady-state concentration being reached after 30 min. Subsequent addition of the non-fluorescent calcium ionophore Br-A23187 resulted in a further increase of 114 ± 18 nM (± SE, n = 18), the higher steady-state concentration being reached after 6 min. The increase in [Ca2+]j induced by solubilized zonae pellucidae was largely blocked by 3-quinuclidinyl benzilate (QNB) an antagonist of muscarinic receptors that was earlier shown to block the zona pellucida induced acrosome reaction in mouse sperm (Florman and Storey, 1982: Dev Biol 91:121-130). This [Ca2+]j increase was completely blocked by the tyrosine kinase inhibitor, tyrphostin A48, and by the inactivator of G1 proteins, pertussis toxin. At the concentrations at which they blocked the zona pellucida-induced increase in [Ca2+]j all three inhibitors also blocked the zona pellucidainduced acrosome reaction. These results indicate that [Ca2+]j increase in is an early, if not the initial, reaction in the sequence leading to zona pellucida induced acrosomal exocytosis in mouse sperm. The observation that the three inhibitors, each having a different mode of action, all block the zona pellucida induced [Ca2+]j suggests that the sperm plasma membrane receptors mediating the zona pellucida induced acrosome reaction may function as a complex, whose formation is activated by zona pellucida ligand binding. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 143-149 
    ISSN: 1040-452X
    Schlagwort(e): Fertility ; Ca2+ uptake ; Head plasma membrane ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Head plasma membranes (HPM) isolated from cryopreserved boar spermatozoa show an excessive fluidization (Buhr et al., Gamete Res 23:441-449, 1989), which might be involved in the loss of fertility. The current study assessed the ability of cold shock (5°C) and phospholipase A2 (PA2) to duplicate these effects on membrane structure and to affect 45Ca2+ uptake and gross morphological characteristics of whole, fresh boar sperm. The HPM from cold-shocked sperm showed a significantly greater rate of fluidization over time than did HPM from control sperm. Addition of PA2 (bee or snake venom, 0.1 or 10.0 ng/ml) to HPM from control sperm caused fluidization similar to cold shocking, but to a lesser degree (P 〈 0.05). Cold-shocked intact sperm exhibited severe acrosomal disruption, loss of motility, and increased 45Ca2+ uptake relative to control sperm. Addition of PA2 (bee or snake venom, 0.1, 1.0., 10.0, and 1,000 ng/ml) to control sperm had not effect on gross morphology or motility while maintaining or increasing sperm extrusion of 45Ca2+. Therefore, although PA2 can, to some extent, duplicate the effects of cold shock on HPM molecular organization, its lipid hydrolytic action is insufficient to cause all the gross disruptions of severe thermal shock. Both PA2 and cold shock disrupted HPM structure, but only cold shock increased 45Ca2+ uptake, suggesting that cold shock may be increasing 45Ca2+ uptake in areas other than the head. Cold shock disrupts sperm on three levels; membrane molecular organization, intracellular Ca2+ regulation, and gross morphology/motility.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1059-910X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 71 (1968), S. 23-32 
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Variants resistant to 2-deoxy-D-glucose have been isolated from a clonal line of pig kidney cells by serial cultivation in the presence of inhibitor. Hexokinase activity may be affected directly in this system, since the oxidation of glucose to 6-phosphogluconate by extracts from sensitive and resistant cells is blocked by the addition of 2-deoxy-glucose to the reaction mixture. This blockage was removed by the addition of glucose-6-phosphate to the system, but not by ATP. Resistant cells were found to accumulate significantly less 2-deoxyglucose-6-phosphate than sensitive cells. The rate of phosphorylation of 2-deoxyglucose, however, was higher in extracts from the resistant line. Alkaline phosphatase does not account for the reduced level of 2-deoxyglucose-6-phosphate since this enzyme is not detectable in sensitive or resistant pig kidney cells. Increased acid phosphatase activity was observed in resistant cells, but extracts with high acid phosphatase activity proved incapable of hydrolyzing either 2-deoxyglucose-6-phosphate or glucose-6-phosphate. In comparative growth studies, cells resistant to 2-deoxyglucose proliferated more extensively than sensitive cells in a low glucose nutrient. They removed glucose more effectively from this medium, and were less stimulated by the addition of intermediates from the tricarboxylic acid cycle. The evidence suggests that resistance to 2-deoxyglucose in the cells under study may be based on the ability of the resistant cells to proliferate at concentrations of glucose too low to support the growth of sensitive cells.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 155 (1993), S. 171-178 
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Previously we showed that CHO cell growth is arrested in the G1 or G0 phase within 24 h after the biosynthesis of mevalonic acid is blocked. The growth-limiting factor under these conditions appeared to be dolichyl phosphate or one of its glycosylated derivatives with consequent decrease in the synthesis of N-linked glycoproteins (Doyle, J.W., and A.A. Kandutsch, 1988, J. Cell Physiol. 137:133-140; Kabakoff, B., J.W. Doyle, and A.A. Kandutsch, 1990, Arch. Biochem. Biophys. 276:382-389). We show herein that cell surface glycoproteins are depleted in the inhibited cultures and that growth arrest is delayed when supraphysiological concentrations of insulin, insulin-like growth factor-1 (IGF-1) and bFGF are added to the culture medium. Apparently an elevated level of a growth factor increases the length of time during which a threshold level of occupied receptor is maintained as the number of glycosylated receptor molecules declines. The results support the idea that cellular levels of dolichyl phosphate and its derivatives may limit cell division by controlling the numbers of functional receptors for growth factors and of other glycoproteins on the cell surface. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0197-8462
    Schlagwort(e): exposure chamber ; psychophysics ; detection ; environmental guidelines ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: The objective of this study was to assess the ability of humans to detect the presence of DC electric fields and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods: one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    BioEssays 19 (1997), S. 985-992 
    ISSN: 0265-9247
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The two vegetative cell types of the acellular slime mould Physarum polycephalum - amoebae and plasmodia - differ greatly in cellular organisation and behaviour as a result of differences in gene expression. The development of uninucleate amoebae into multinucleate, syncytial plasmodia is under the control of the mating-type locus matA, which is a complex, multi-functional locus. A key period during plasmodium development is the extended cell cycle, which occurs in the developing uninucleate cell. During this long cell cycle, many of the changes in cellular organisation that accompany development into the multinucleate stage are initiated including, for example, alterations in microtubule organisation. Genes have been identified that show cell-type specific expression in either amoebae or plasmodia and many of these genes alter their pattern of expression during the extended cell cycle. With the introduction of a DNA transformation system for P. polycephalum, it is now possible to investigate the functions of genes in the vegetative cell types and their roles in the cellular reorganisations accompanying development.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 118-126 
    ISSN: 0741-0581
    Schlagwort(e): Freeze-fracture ; Cryotechniques ; Humidity ; Temperature control ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Rapid freezing is the most important step in sample preparation for freeze-fracture and other cryotechniques for electron microscopy. We present the design and operation of a simple environmental chamber coupled to a plunger-driven freezing device that has provided simple and reliable freezing from temperatures and humidities other than ambient. The chamber can be constructed and operated with equipment and techniques common to most electron microscopy labs. Temperature control of ±0.1°C and relative humidities of 〉90% were provided over the range -5-60°C. Typical electron micrographs showing well preserved structures comparable to jet-freezing are presented.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2002-08-10
    Beschreibung: Primate-specific segmental duplications are considered important in human disease and evolution. The inability to distinguish between allelic and duplication sequence overlap has hampered their characterization as well as assembly and annotation of our genome. We developed a method whereby each public sequence is analyzed at the clone level for overrepresentation within a whole-genome shotgun sequence. This test has the ability to detect duplications larger than 15 kilobases irrespective of copy number, location, or high sequence similarity. We mapped 169 large regions flanked by highly similar duplications. Twenty-four of these hot spots of genomic instability have been associated with genetic disease. Our analysis indicates a highly nonrandom chromosomal and genic distribution of recent segmental duplications, with a likely role in expanding protein diversity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bailey, Jeffrey A -- Gu, Zhiping -- Clark, Royden A -- Reinert, Knut -- Samonte, Rhea V -- Schwartz, Stuart -- Adams, Mark D -- Myers, Eugene W -- Li, Peter W -- Eichler, Evan E -- CA094816/CA/NCI NIH HHS/ -- GM58815/GM/NIGMS NIH HHS/ -- HG002318/HG/NHGRI NIH HHS/ -- New York, N.Y. -- Science. 2002 Aug 9;297(5583):1003-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics, Center for Computational Genomics, and Center for Human Genetics, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, Cleveland, OH 44106, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12169732" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Alleles ; Base Sequence ; Biological Evolution ; Chromosomes, Human/genetics ; Computational Biology ; Databases, Nucleic Acid ; Exons ; Expressed Sequence Tags ; *Gene Duplication ; Gene Rearrangement ; *Genes, Duplicate ; Genetic Diseases, Inborn/genetics ; *Genome, Human ; Humans ; Models, Genetic ; Polymorphism, Single Nucleotide ; Proteome ; Recombination, Genetic ; Sequence Alignment
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 1999-11-30
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉O'Brien, S J -- Eisenberg, J F -- Miyamoto, M -- Hedges, S B -- Kumar, S -- Wilson, D E -- Menotti-Raymond, M -- Murphy, W J -- Nash, W G -- Lyons, L A -- Menninger, J C -- Stanyon, R -- Wienberg, J -- Copeland, N G -- Jenkins, N A -- Gellin, J -- Yerle, M -- Andersson, L -- Womack, J -- Broad, T -- Postlethwait, J -- Serov, O -- Bailey, E -- James, M R -- Marshall Graves, J A -- New York, N.Y. -- Science. 1999 Oct 15;286(5439):463-78.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Cancer Institute, Frederick, MD, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10577209" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Base Sequence ; *Chromosome Mapping ; Chromosome Painting ; *Genome ; *Genome, Human ; Humans ; Mammals/*genetics ; Nucleic Acid Hybridization ; Phylogeny
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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