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  • 1
    Digitale Medien
    Digitale Medien
    Sublethal Cytotoxic Effects of Mercuric Chloride on the Ciliate Tetrahymena pyriformis (1973)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 20 (1973), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SYNOPSIS. The behavior and ultrastructure of Tetrahymena pyriformis was assessed after exposure to dosages of 8 and 16% of the lethal concentration of HgCl2 (TLm 96 hr). The lower dosage caused no abnormal changes in cell motility, activity of the water explusion vesicles, or cell shape; the higher dosage caused deleterious changes in these parameters. The higher sublethal HgCl2 concentration (0.50 mg/liter) elicited damage of several cell structures. This damage persisted and accumulated with time up to 24 hr. At the lower HgCl2 dosage (0.25 mg liter) there were extensive changes after 1-hr exposure involving primarily mitochondria; however, all major changes were repaired after 24 hr of constant exposure to the HgCl2, indicating adaptation to the toxicant. Based solely on cytotoxic evidence an attempt is made to apply the findings defining what constitutes a “safe'’concentration of HgCl2 in the cell's environment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.1973.tb00882.x
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  • 2
    Digitale Medien
    Digitale Medien
    A Periodicity of Tritiated-thymidine Incorporation into Cytoplasmic Deoxyribonucleic Acid during the Cell Cycle of Tetrahymena pyriformis (1966)
    [s.l.] : Nature Publishing Group
    Nature 209 (1966), S. 630-631 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The purpose of this communication is to establish whether or not a relationship exists between cytoplasmic DNA replication and the DNA replication in the micro- or macro-nucleus of the cell. Tetrahymena pyriformis strain HSM is known to replicate its micronuclear DNA during a half-hour period at ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/209630b0
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  • 3
    Digitale Medien
    Digitale Medien
    Aspirin, but Not Sodium Salicylate, Indomethacin, or Nabumetone, Reversibly Suppresses 1,2-Dimethylhydrazine-Induced Colonic Aberrant Crypt Foci in Rats (1997)
    Springer
    Digestive diseases and sciences 42 (1997), S. 920-926 
    Details
    ISSN: 1573-2568
    Schlagwort(e): ASPIRIN ; SODIUM SALICYLATE ; INDOMETHACIN ; NABUMETONE ; PROSTAGLANDIN E2 ; ABERRANT CRYPT FOCI ; CARCINOGENESIS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The aim of this study was to determine ifselective inhibition of cyclooxygenase isozymes affectsthe initiation of carcinogen-induced colon cancer usingaberrant crypt foci (ACF) as a surrogate biomarker. Male Sprague-Dawley rats (18 per group) weregiven single subcutaneous injections of saline (4ml/kg), aspirin (50 mg/kg body wt) sodium salicylate (50mg/kg), indomethacin (4 mg/kg), nabumetone (100 mg/kg), or 16,16-dimethyl-prostaglandin E2(50 mg/kg) for three days. On day 4, 12 rats per groupwere given a subcutaneous injection 2 of1,2-dimethylhydrazine (12 mg base/kg body wt) and sixrats per group received vehicle alone (4 ml/kg) every week for eightweeks, after which drug treatment ceased. Control andsix carcinogen-treated rats per group were killed atthis time and the remaining six rats per group killed 22 weeks later. Colons were scored for ACFnumber and size. Only aspirin caused a significantreduction in total ACF and ACF formation at the earlytime point, but at the later time, there were nosignificant differences between groups. ACF from alltreatment groups increased in size at similar rates atboth time points. Thus, only aspirin demonstrated asignificant, although reversible, suppression ofcarcinogen-induced ACF. Possible mechanisms of action and theclinical implications of aspirin chemoprevention arediscussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018812430512
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  • 4
    Digitale Medien
    Digitale Medien
    The pineal gland of the gerbil, Meriones unguiculatus (1979)
    Springer
    Cell & tissue research 204 (1979), S. 95-109 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Gerbil ; Pinealocytes ; Morphometric analysis ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary By means of morphometric analytical procedures, a diurnal rhythm in the cellular volume of gerbil pinealocytes was determined. This rhythm has been attributed primarily to a change in the cytoplasmic volume of the pinealocytes which is low during the daylight hours and increases to reach a peak during the middle of the dark period. At the ultrastructural level, six cytoplasmic components of the pinealocytes were found to exhibit a rhythm: free cytoplasm, smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER) and ribosomes, secretory vesicles, microtubules, and mitochondria. The presumptive secretory vesicles and the microtubules reached a peak in volume one hour before lights-off. It is suggested that lights-on and lights-off both signal a decrease in size and/or number of the secretory vesicles. The SER and RER/ribosomes reached their peak volume one hour after lights-off which is interpreted as indicating a peak in indoleamine synthesis and protein synthesis, respectively. The volume of free cytoplasm exhibits two peaks; one occurs one hour before lights-off while the second peak occurs in the middle of the dark phase. It is suggested that, although part of the secretory product of the pinealocyte may be present in dense-cored vesicles, other locations could include the free cytoplasm and clear secretory vesicles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235167
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  • 5
    Digitale Medien
    Digitale Medien
    Age alters expression and inducibility of heme oxygenase isozymes in mice (1998)
    Springer
    Age 21 (1998), S. 123-128 
    Details
    ISSN: 1574-4647
    Schlagwort(e): Age ; fatty acids ; heme oxygenase ; mice ; oxidative stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Heme oxygenase (HO) performs the rate limiting step in heme degradation and is induced by cell injury or stress. We wished to determine if dietary fatty acid composition, increased age and/or an induced oxidative stress would alter the expression of HO-1 (constitutive and inducible isozyme) or of HO-2 (constitutive isozyme), in mouse liver, spleen and brain. Six-and 24-month-old male B6C3F1 mice were fed AIN-76A diets containing either 5% corn oil (CO, moderately unsaturated, n=5 per age group) or 19% menhaden fish oil plus 1% corn oil (FO, highly polyunsaturated, n=20 per age group). After 2 weeks, 5 CO and 5 FO fed mice in each age group were sacrificed. The remaining FO diet mice (n=15 per age group) were then challenged with a systemic oxidative stress by intraperitoneal injection of 125 mg iron/kg body weight as iron dextran. Five stressed mice from each age group were sacrificed 1, 5, and 24 hours post injection; liver, spleen and brain were removed. Part of each tissue was fixed in formalin, and microsomal protein isolated from the remaining tissue. HO-1 and HO-2 were detected by immunoblot of microsomal protein and by immunohistochemical staining of fixed tissue in the liver and spleen, but only HO-2 was detected in the brain. There was no significant difference in HO-1 or HO-2 expression due to diet. The liver of old unstressed mice had significantly more HO-1 than young mice. However, HO-1 was significantly induced in the livers of young mice, but not of old mice, following oxidative stress. Spleen HO-1 expression was not significantly altered by age or oxidative stress. HO-2 expression was not significantly altered by age or induced oxidative stress in any tissue examined. Age-related alterations in liver HO-1 isozyme expression and inducibility may contribute to increased susceptibility to exogenous stress and disease.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s11357-998-0019-3
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  • 6
    Digitale Medien
    Digitale Medien
    The type of chemical fixative affects the immunohistochemical localization of transforming growth factor alpha in rat colon crypts (1998)
    Springer
    Journal of molecular histology 30 (1998), S. 301-305 
    Details
    ISSN: 1573-6865
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The effects of the different fixation agents, Omnifix, 10% neutral-buffered formalin, 70% ethanol, acetone, 10% neutral-buffered formalin, for 2 h followed by 70% ethanol for 10 h or 40% paraformaldehyde on the immunohistochemical localization of transforming growth factor alpha in rat colon crypts were studied. Segments of rat descending colon were fixed and then processed for immunohistochemistry using a monoclonal antibody to the growth factor. The results showed that the pattern of transforming growth factor alpha staining in the colonic crypts differed and was distinct for each fixative. © 1998 Chapman & Hall
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003272109137
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  • 7
    Digitale Medien
    Digitale Medien
    Electron probe microanalysis of elemental composition of mouse cardiac myocytes during post-natal maturation (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 100 (1979), S. 305-310 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Elemental concentrations in the cytoplasm and nucleus of post-natal mouse myocytes were measured at 2, 4, 8, 16, 32 days and in adults using electron probe X-ray microanalysis. Using an analysis of variance test, significant age dependent changes were found in intracellular potassium, sulfur, phosphorus, and chlorine concentations (mg/kg dry weight), while sodium and magnesium concentrations did not show significant changes. The application of t tests following linear regression analyses (age versus concentration for each element) did, however, give a significant slope for cytoplasmic sodium, potassium, sulfur, and phosphorus values. The findings correspond closely with an emission spectroscopy-titrimetric study of whole heart ventricle of the same developmental period (Hazelwood and Nichols, '70).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041000211
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  • 8
    Digitale Medien
    Digitale Medien
    An X-ray microanalysis survey of the concentration of elements in the cytoplasm of different mammalian cell types (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 493-501 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Electron probe energy dispersive X-ray microanalysis was performed on freeze-dried tissue sections. The dry weight concentration of elements (mmole/kg dry weight) was measured in the cytoplasm of several cell types from adult mice and rats. This comparative investigation showed: (1) That the energy dispersive X-ray spectrum of element concentration from the cytoplasm of a specific cell type allows one to distinguish this specific cell type from other cell types with considerable accuracy. (2) That there is a relationship between the concentration of the various elements and the ultrastructural features of the cytoplasmic regions being analyzed. For example, areas rich in ribosomes are also rich in P, K and Mg. (3) These data support the idea that K is directly involved in the control of protein synthesis. The catalog of element concentrations in the cytoplasm of 13 cell types from both mice and rats should be of value to others who seek to answer various questions about these cell types.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041010315
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  • 9
    Digitale Medien
    Digitale Medien
    Intracellular concentration of potassium and other elements in vaginal epithelial cells stimulated by estradiol administration (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 104 (1980), S. 121-125 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Electron probe x-ray microanalysis was used to measure cytoplasmic elemental content (in mmoles/kg dry weight) of the basal layer of cells of the vaginal epithelium of ovariectomized rats. Measurements were made both before estradiol injection and at 2 hr, 17 hr, and 24 hr after estradiol administration. Mitotic figures first appeared in the basal cell layer at 24 hr. During the course of the study significant time-dependent differences were seen in the content of all elements measured. A pattern of change in cytoplasmic content was seen for Na, P, S, and Cl; all of which decrease significantly by 17 hr and then return to approximately the nonstimulated concentration by 24 hr. On the other hand K, and to a lesser extent Mg, show an early and continued increase in cytoplasmic content after estradiol injection. Thus, the marked increase in the intracytoplasmic content of K in the estradiol treated cells suggests that K, or the ratio of Na to K, may be directly or indirectly involved in growth stimulation.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041040115
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  • 10
    Digitale Medien
    Digitale Medien
    Characterization of water in unfertilized and fertilized sea urchin eggs (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 127 (1986), S. 439-447 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The water in unfertilized and fertilized sea urchin eggs was characterized with a proton nuclear magnetic resonance (NMR) titration method assuming fast proton diffusion (FPD) between water compartments. This method involves stepwise dehydration with sequential T1 relaxation time and water content determinations. The results analyzed by the FPD model give evidence of intracellular water compartments with three different correlation times: 6 × 10-12 sec (bulk water), 1 × 10-10 sec (structured water) and about 2 × 10-9 sec (bound water). Fertilization is accompanied by a substantial increase in bulk water (from 111 to 414 g H2O per 100 g dry mass) and by a decrease in the water of hydration (from 128 g to 56 g per 100 g dry mass). This study shows that 54% of the water in the unfertilized sea urchin egg has motional properties different from bulk water and that this percentage decreases dramatically shortly after fertilization. Most of the change in T1 relaxation rate observed at fertilization can be accounted for by uptake of bulk water associated with elevation of the fertilization membrane.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041270313
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