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  • 1
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three experiments were performed to evaluate the potential for parthenogenetic activation of bovine oocytes in in vitro fertilization systems and to determine the chromosome complement of the resulting parthenogenotes. In the first experiment, immature oocytes from slaughtered cattles were matured in vitro in Defined Medium (DM) for 24 h to simulate in vitro fertilization conditions. Subsequently, a portion was fixed, and the remainder were transferred to rabbit oviducts. Oocytes were then cultured for 6-8 h or for 24 h with Colcemid present during the last 6 to 8 h and fixed on slides and examined. In the second experiment, mature oocytes were collected from the preovulatory follicles, and the oocytes were subjected to the same culture as in experiment I. In the third experiment, oocytes were treated as in experiment II, except that instead of transfer to rabbit oviducts, they were cultured an additional 48 h in vitro. In experiment I, 131 oocytes were fixed after culture in DM. Of the 79 oocytes analyzed in the pre-rabbit group, 71 (90%) were at the second meiotic metaphase (MII), and 8 (10%) were at pre-MII stage; none were activated. After transfer to rabbits, 291 were fixed. Of these, 80 were analyzed; 37 (46.3%) were MII, 7 (8.6%) were pre-MII, and 36 (45%) were activated. Of the 36 activated oocytes, 26 (72.2%) were haploid, 4 (11.1%) were diploid, 1 (12.8%) was tetraploid, and 5 (13.8%) were in the process of endoreduplication. In experiment II, 51 oocytes were fixed after culture in DM of which 36 (70.6%) could be analyzed; 30 (83.3%) were MII, and 6 (16.7%) were pre-MII. After culture in the rabbit, 68 were fixed of which 27 (39.7%) could be analyzed. Of these 27, 20 (74.1%) were MII, and 7 (25.9%) were activated; 6 were haploid, and 1 was endoreduplicating. In experiment III, 30 oocytes were fixed at the end of the culture period; only 10 could be analyzed of which 8 (80%) were MII and 2 (20%) were pre-MII. In all, 46% of in vitro and 26% of in vivo matured oocytes were activated, based on chromosomal analysis. Of those activated, the majority (74.4%) were haploid, suggesting that activation occurs at or after completion of MII. Endoreduplication appears to be one of the mechanisms leading to the formation of diploid and polyploid parthenogenotes.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 19 (1988), S. 305-314 
    ISSN: 0148-7280
    Keywords: radiation inactivation ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The molecular weight of the active unit of phospholipase A2 (PA2) in human seminal plasma and spermatozoa was determined using the radiation inactivation technique. Fresh spermatozoa possess more than one form of PA2 activity as judged by the biphasic nature of the curve obtained during enzyme inactivation. However, when stored frozen for several months followed by a period of heating for 60 min at 60 °C prior to irradiation, the sperm exhibited PA2 activity, which corresponded to a single low molecular mass form of 12,000 d when radioactive phosphatidylcholine (PC) was used as substrate and 8,000 d when radioactive phosphatidylethanolamine (PE) was used as substrate. In fresh seminal fluid, only one active form of PA2 was detected as judged by the linear nature of the curve obtained during enzyme inactivation by irradiation. Using PC as substrate, the active unit was again estimated to be 12,000 d, whereas it corresponded to 18,000 d when PE was used. The PA2 activity associated with normal spermatozoa exhibited a 60% decrease in activity after storage at -20 °C for 48 hr followed by a heating period of 10 min at 60 °C. Long-term storage of spermatozoa at -20 °C also resulted in a similar decrease in the deacylation of PC. No further loss of activity was observed during subsequent heat treatment at 60 °C. Seminal plasma, however, showed no loss of activity following short (48 hr at 4 °C or -20 °C) or long-term storage and subsequent heat treatment. Thus, the behavior of PA2 when the effect of temperature was studied and in radiation inactivation experiments indicates that the low molecular weight component in the seminal plasma as well as in spermatozoa is temperature resistant. However, in fresh spermatozoa, a second form of PA2 was found and was sensitive to changes in temperature.
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  • 3
    ISSN: 0730-2312
    Keywords: elastase inhibitors ; β-lactams ; lung damage ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human polymorphonuclear leukocyte elastase (PMN elastase) is inhibited by L-659, 286 (7α-methoxy-8-oxo-3-[[(1,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triaz-in-3-yl)thio]methyl]-5-thia-1-aza-6R-bicyclo [4.2.O]oct-2-ene-2-pyrrolidine carboxamide-5,-dioxide) with a Ki of 0.4 μM. This inhibition is time-dependent, rapid, and only slowly reversible, with a t1/2 of 〉 3 days at 25°C. L-659, 286 is also highly selective for PMN elastase, as it does not inhibit thrombin, trypsin, papain, plasmin, chymotrypsin, or cathepsin G. L-659, 286 administered intratracheally inhibits lung damage caused by administration via the same route of human PMN elastase into hamsters. In marmosets, L-659, 286 is cleared from blood very rapidly after an intravenous injection but is recovered in bronchoalveolar lavage fluid for several hours after intratracheal administration.
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The addition of low concentrations (〈10-7 M) of the calcium ionophore A23187 to rabbit neutrophils re'eases the intracellular pool of calcium previously shown in radioactive steady-state and chlortetracycline fluorescence studies to be mobilized by chemotactic factors. A23187 at these concentrations elicits no functional responses from these cells. However, A23187, added before chemotactic factors such as fMet-Leu-Phe and leukotriene B4, inhibits the ability of the latter stimuli to induce, in the presence of cytochalasin B, an exocytotic release of the neutrophil's cytoplasmic granules. These results imply that the chemotactic-factor-induced release of intracellular calcium is a necessary event for the optimal activation of the neutrophils. Phorbol esterinduced neutrophil degranulation on the other hand is unaffected by exposure to A23187, thereby completely dissociating its mechanism of action from rises in cytoplasmic free calcium.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 138 (1989), S. 548-554 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of activation of protein kinase C on stimulation of ornithine decar-boxylase (ODC) activity and cAMP production was studied in fetal rat osteoblasts. Both phorbol 12-myristate, 13-acetate (PMA), an activator of protein kinase C, and 4α-phorbol, ineffective in activating protein kinase C, failed to stimulate ODC activity and cAMP production. We tested the effect of protein kinase C on stimulation of ODC activity by parathyroid hormone (PTH) and forskolin. In contrast to PTH-stimulated ODC activity, which was not affected by PMA, forskolin-stimulated (1 and 10 μM) ODC activity was dose dependently reduced. PMA (400 nM) reduced both 1 and 10 μM forskolin-stimulated ODC activity to the same level, ∼ 3 nmol CO2/mg protein, which suggests a controlling role of protein kinase C in forskolin-stimulated ODC activity. The study of the effect of protein kinase C on PTH- and forskolin-stimulated cAMP production also revealed differences between PTH and forskolin. When PMA was added simultaneously with PTH (4 and 20 nM) or forskolin (1 and 10 μM) the PTH-stimulated cAMP production was dose-dependently potentiated by PMA, whereas forskolin-stimulated cAMP production was not affected. However, both PTH- and forskolin-stimulated cAMP production was dose-dependently augmented when PMA was added 3 min prior to PTH or forskolin. With increasing preincubation periods (up to 24 h) with PMA instead of a potentiation an inhibition was observed. This inhibition is not due to PTH receptor desensitization, although, on basis of the present results desensitization can not completely be excluded. In all cases 4α-phorbol was without effect. The present results show that protein kinase C modulates stimulation of ODC activity and cAMP production in fetal rat osteoblasts. The modulation of both ODC activity and cAMP production appears to be dependent on the nature of the stimulator. The present data suggest a role for protein kinase C in limiting the cAMP-mediated stimulation of ODC activity in these cells. Furthermore, it is suggested that protein kinase C can interfere at more than one site in the cAMP-generating system.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 488-494 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of cAMP and calcium in the induction of ornithine decarboxylase (ODC, E.C.4.1.1.17) activity in the osteogenic sarcoma cell line, UMR 106-01, was studied, with particular interest for parathyroid hormone (PTH). PTH and forskolin dose-dependently induced the ODC activity and the cAMP production. Protein synthesis is involved in the effect of PTH and forskolin on ODC activity but not on cAMP production. Using quin2 we showed that 20 nM PTH and 10 μM forskolin increased the intracellular ionized calcium concentration ([Ca2+]i), thereby offering the possibility for calcium to play a role as cellular mediator in the action of PTH and forskolin in bone. Data obtained with A23187 showed that solely an increase of the [Ca2+]i is not sufficient to stimulate basal or potentiate PTH- and forskolin-induced ODC activity. However, the effects of calcium channel blockers and EGTA on basal and PTH- and forskolin-induced ODC activity point to a specific role for calcium. Moreover, the effects of calcium channel blockers and EGTA on basal and PTH- and forskolin-induced cAMP production indicate that the involvement of calcium in the induction of ODC activity is primarily located at another site than the adenylate cyclase. These data indicate that calcium is involved in the control of basal ODC activity. Furthermore, these data suggest that both cAMP and calcium are involved in the induction of ODC activity by PTH and forskolin. More precisely, ODC activity in UMR 106-01 cells can be induced by PTH and forskolin via a calcium-dependent cAMP messenger system.
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  • 7
    ISSN: 0886-1544
    Keywords: video microscopy ; axonal transport ; computer motion analysis ; giant axon ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Moving intra-axonal organelles demonstrate frequent variations in speed when viewed over several seconds. To evaluate these and other motion variations, a long-term analysis of organelle motion in isolated axoplasm of Myxicola infundibulum was carried out using differential interference contrast optics and analog and digital image enhancement techniques. Motion characteristics of individual organelles were analyzed for periods of up to 58 minutes. Three principle observations on organelle motion were made: (1) Classes of organelles of the same size demonstrated a 5- to 25-fold variation of speed, with the slowest speeds occurring most frequently; (2) organelle speeds over individual translocations (motion without stopping) are inversely proportional to their size, but the speeds calculated for the long-term analysis of organelle motion (total distance travelled/total observation time, including pauses) did not reflect this observation; and (3) organelles displayed variable trip lengths, durations, mean speeds, and pause durations, and the relationships between these variations showed no repetitive patterns. In contrast to reported observations of uniform velocities of organelles moving on isolated microtubule preparations, these observations suggest that a variety of factors must play a role in organelle translocation in Myxicola axoplasm.
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  • 8
    ISSN: 0148-7280
    Keywords: follicular fluid ; alpha1-antitrypsin ; follicular volume ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The aim of this study has been the development of a noninvasive method of predicting the pregnancy potential of human oocytes and embryos intended for in vitro fertilization and embryo replacement. A multifactorial system which distinguishes, with a high degree of accuracy, between normal pregnancy, abnormal pregnancy, and non-pregnancy-producing embryos is reported. The variables included are (1) follicular fluid proteins alpha1-antitrypsin, complement C3, immunoglobulin IgG2, and total protein, and total proteoglycan level separated by isoelectric focusing; (2) follicular volume; and (3) an embryo appearance rating. The study group consisted of (1) follicles which produced embryos of known performance after transfer (a) when the number of embryos transferred = the number of implantations and, (b) where one embryo transferred = no pregnancy; (2) follicles which produced oocytes which did not cleave after insemination; and (3) follicles from which no oocyte was aspirated. Canonical discriminant analysis of follicular fluid variables and follicular volume has been used to characterize the oocyte performance groups. Correct classification was achieved in 69% of normal pregnancy, 70% of abnormal pregnancy, 33% of no pregnancy, and 47% of no cleavage oocytes. An embryo appearance rating was included with the above variables for a separate discriminant analysis of only those oocytes which had formed embryos after insemination. Correct classification was achieved in 81% of normal-pregnancy, 70% of abnormal-pregnancy, and 70% of nopregnancy embryos.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 59-74 
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; cell cohesion ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three stage-specific cohesive systems operate in D. discoideum: VEG, elaborated by vegetative cells: AR, by aggregation competent cells; and PAR, by post aggregation stage cells. Previous study of a mutant strain JC-5 had shown the stability of its PAR system (but not the AR) to be temperature sensitive. However, the phenotypic expression of this mutation termed Coh A is complicated by the presence in that strain of a preexisting mutant gene Rde A, which accelerates developmental events generally and alters the pattern of morphogenesis. Genetic evidence presented here indicates that the two mutations have been separated by parasexual recombination yielding a Coh A, Rde A+ segregant class of which strain JC-36 is a prototype.At the permissive temperature, JC-36 follows a morphogenetic sequence like that of the wild type in respect to timing, morphogenetic pattern, and spore appearance. At the restrictive temperature, it forms normal aggregates at the usual time but exhibits two morphogenetic aberrancies during post aggregative development. First, fruit construction is arrested at a stage approximating the 16 hr “Bottle” stage of the wild type, though more squat and blunt tipped, and then the aggregate regresses. Cytodifferentiation into spores and stalk cells is also blocked. Second, a shift of slugs migrating normally at the permissive temperature to the restrictive causes the latter to disintegrate progressively as they leave clumps of cells behind them within the flattened sheath.JC-36 cells developing at the restrictive temperature also exhibited a decrease in EDTA resistant cohesivity attributable on two grounds to the sensitivity of the PAR system. In addition, the disappearance of the AR system completed in the wild type by the Mexicanhat (18-19 hr) stage is indefinitely arrested at an intermediate level in JC-36.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 8 (1987), S. 9-21 
    ISSN: 0197-8462
    Keywords: avain embryogeny ; quail eggs ; radiation ; progeny reproductive performance ; birds ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Japanese quail (Coturnix coturnix japonica) embryos were irradiated continuously in ovo with 2.45-GHz continuous wave radiation during the first 12 days of embryogenesis at an incident power of 5 mW/cm2 and a specific absorption rate of 4.03 mW/g. The internal temperature of irradiated and nonirradiated (sham) eggs was 37.5 ± 0.3 °C, which is the optimum temperature for incubating quail eggs. At 35 days after hatching irradiated and sham-irradiated males were paired with irradiated or sham-irradiated females and daily records of reproductive performance were collected through 224 days of age. Progeny were hatched from each of the male-female pairs, and progeny reproductive performance was measured from 35 through 168 days of age. Hatchability was not affected by irradiation during embryogeny. Mortality after hatching, egg production, egg weight, fertility, hatchability of eggs produced, and reproductive performance of the progeny were not affected by irradiation during embryogeny. These observations indicate that irradiation of quail embryos with low-level microwave radiation does not affect the reproductive capacity of the hatchlings or of progeny produced from quail irradiated during incubation.
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