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  • 1980-1984  (5)
  • 1930-1934
  • Life and Medical Sciences  (5)
  • 1
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The applicability of the four-parameter model for physiological responses to the prediction of food intake and corresponding weight gain and individual organ weight gain was studied further in 40-day postpartum male rats. Seven groups of animals were maintained on diets in which protein content ranged from 0 to 23.54% casein. Food intake and weight gain were recorded every other day for each animal for 21 days. At the termination of the experiment the following organs were removed and weighed: liver, heart, lungs, spleen, kidneys, adrenals, and testes. When these weight values are fitted by use of the four-parameter model, food intake and total animal and organ weight gains can be predicted in relation to the amount of protein in the diet. It was found that liver, heart, lungs, spleen, and whole animal had similar K(0.5) values. However, it was also shown that there is variation in response of organs when relating organ weight as a percentage of body weight. For example, heart, lungs, and testes show an increased ratio on low protein diet while liver, kidneys, and adrenals maintain a fairly constant ratio and the spleen shows a decreased ratio. Additionally, it was noted that the animals on low protein diet consumed more food per gram body weight but did so at a slower rate. Possible future applications of the four-parameter model for physiological reponses are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 162 (1981), S. 369-382 
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Previous studies on ultrastructural changes that occur in cultured human fibroblasts during their in vitro life-span indicate that “senescent” cells characteristically possess structurally altered mitochondia, highly lobed nuclei, and an abundance of secondary lysosomes when compared to early passage cells. In the present study, we demonstrate that improper preparative methods can induce altered mitochondrial morphology in preparations of both IMR-90 and HF730A fibroblasts, regardless of passage level. We also show that nuclei of both living and fixed IMR-90 fibroblasts are ovoid in shape, not lobulate, in well-spread cells, regardless of either the passage level or the proliferative capacity of the cell. Fibroblasts contain lobulated nuclei only when they have not spread completely on the culture substrate. Lobulations can be induced at any passage level by collagenase/trypsin or trypsin/EDTA treatment prior to fixation, but not by cytochalasin B treatment or by cold temperatures. We conclude that any treatment that affects cytoskeleton-membrane-culture substrate interactions will induce this aberrant nuclear morphology, but that this is not indicative of “senescence” and does not relate to proliferative decline.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 164 (1982), S. 255-263 
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Early-, mid- and late-passage cultures (population doubling levels 12, 35, and 51, respectively) of IMR-90 fibroblasts were exposed to 3H-thy-midine for 48 h prior to fixation in situ for morphometric analysis in order to determine quantitatively what ultrastructural changes accompany the loss of proliferative capacity during aging in vitro. Analysis of autoradiographs, both at the light and electron microscopic levels, with an image analyzer followed by ANOVA statistical scrutiny demonstrated that a significant increase in relative cell area, an indicator of cell size, was characteristic of cells unable to incorporate 3H-TdR at both mid- and late-passage, but not at early-passage levels. Nuclear size also increased significantly with progressive passage level but was not related to proliferative capacity. No significant difference in the area fraction of nucleoli per unit area of nucleus or of mitochondria, Golgi, or lysosomes was seen in either subpopulation at any passage level. Dilated cisternae of rough endoplasmic reticulum in early-passage cells were seen if cells were harvested with trypsin and fixed either before or after centrifugation, but were not seen in labeled or unlabeled cells from any passage level when cultures were fixed in situ. We conclude that a significant increase in cell size is the only significant morphological change associated with the loss of proliferative capacity of IMR-90 fibroblasts. Furthermore, our data indicate that there is no accumulation of secondary lysosomes in human diploid fibroblasts during aging in vitro; we therefore cannot support any hypothesis of aging or proliferative decline that is based mechanistically upon this phenomenon.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 104 (1980), S. 121-125 
    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
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 0192-253X
    Schlagwort(e): urate oxidase ; 20-hydroxyecdysone ; Drosophila melanogaster ; Malpighian tubules ; Life and Medical Sciences ; Genetics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: The tissue-specific enzyme urate oxidase is confined exclusively to the Malpighian tubules of Drosophila melanogaster and expressed only in the third-instar larva and the adult. Shortly before pupariation urate oxidase activity declines precipitously and is not detectable 24 hours later. That 20-hydroxyecdysone is the factor that triggers the disappearance of urate oxidase activity in late third-instar larvae is demonstrated using the temperature sensitive mutant ecd1 which at the nonpermissive temperature of 29°C fails to accumulate a sufficient concentration of 20-hydroxyecdysone necessary for puparium formation and thus remains a third-instar larva for 1 to 2 weeks before death. Both the life cycle and the temporal profile of urate oxidase activity in ecd1 larvae at 19°C is identical to that of the wild type. However, at 29°C ecd1 third-instar larvae retain high urate oxidase activity. A precipitous decline in urate oxidase activity is observed when ecd1 larvae at 29°C are fed 20-hydroxyecdysone. These data implicate 20-hydroxyecdysone in the process that controls the rapid decline of urate oxidase activity at the time of puparium formation. In whole homogenates of Malpighian tubules, the urate oxidase polypeptide was identified in SDS-polyacrylamide gels by its Rf with respect to homogeneously pure Drosophila urate oxidase and also by immunoprecipitation with rabbit anti-Drosophila urate oxidase IgG. Throughout development the amount of the urate oxidase polypeptide is correlated with the magnitude of urate oxidase activity.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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