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  • Rat  (115)
  • Phytochrome  (56)
  • Springer  (171)
  • American Meteorological Society
  • Blackwell Publishing Ltd
  • International Union of Crystallography
  • Springer Nature
  • 2020-2022
  • 1975-1979  (171)
Collection
Publisher
  • Springer  (171)
  • American Meteorological Society
  • Blackwell Publishing Ltd
  • International Union of Crystallography
  • Springer Nature
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 23 (1977), S. 161-170 
    ISSN: 1432-0827
    Keywords: Bone ; Growth ; Rat ; Remodeling ; Tetracyclines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Cortical bone remodeling along the femur diaphysis was determined in normal female rats (Sprague-Dawley) with the tetracycline technique. Three segments on the cortical bone circumference (the anterolateral, the medial, and the posterior) were found to be most suitable for the study of the remodeling process. Oxytetracycline was administered at age 60 and 75 days, and groups of animals were killed at age 75, 85, 95, and 105 days. The accumulated endosteal growth during age 60 to 75 days in the anterolateral segment was found to increase uniformly in the distal direction along the femur diaphysis. A method is described where this accumulated endosteal growth is used. This method eliminates the use of calipers to determine the section level and makes it possible to study comparable sections even after varying periods of time. The proximal part of the diaphysis showed periosteal apposition in all three segments. The periosteal apposition turned into resorption in the distal part of the diaphysis in the anterolateral and medial segments, whereas the periosteal appsition increased in the posterior segment. The endosteal growth increased in the distal direction in the anterolateral and medial segments. Irregular OTC bands made measurements of endosteal remodeling in the posterior segment impossible. The cortical width decreased in the distal direction along the femoral shaft. Comparison between the different age groups is described and also the relation between the accumulated endosteal growth and the diameter of the medullary cavity.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 27 (1979), S. 161-164 
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Ovary ; Rat ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Fifty adult female rats were used to study the effect of 1-alpha-hydroxyvitamin D3 (1α-OH-D3)on bone after oophorectomy. The experimental period was 6 months. At the end of the experiment the femurs and the tibias were investigated for bone mass and composition. Significant signs of osteopenia occurred as a result of oophorectomy. The treatment with 1α-OH-D3 induced only minor changes in blood chemistry but increased bone mass significantly. The findings support the view that 1α-OH-D3 may be a valuable tool in the treatment of osteoporosis resulting from ovarian insufficiency.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 55 (1975), S. 53-55 
    ISSN: 1573-0832
    Keywords: Rubratoxine B ; Mitochondria ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The in vitro effect of rubratoxin B on the electron transport system of rat liver mitochondria was investigated. This mycotoxin depressed oxygen consumption in ADP-lacking mitochondria and in ADP-coupled mitochondria, using succinate or β-hydroxybutyrate as substrats. Rubratoxin B is neither an oxidative-phosphorylation inhibitor nor uncoupling agent. Its effect is compared with aflatoxin B1.
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  • 4
    Electronic Resource
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    Springer
    Calcified tissue international 25 (1978), S. 75-83 
    ISSN: 1432-0827
    Keywords: Rat ; Fluorosis ; Enamel ; Scanning electron microscopy ; Low temperature incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Sixteen 58-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. These changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.
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  • 5
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    Calcified tissue international 22 (1977), S. 77-84 
    ISSN: 1432-0827
    Keywords: Fluoride ; Blood plasma ; Enamel mineralization ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract It is postulated that tissue fluid F concentrations are the primary determinants of fluoride effects on bones and developing teeth and that these concentrations are dependent on, or mirrored by, blood plasma F. It has earlier been shown that the plasma F levels are dependent on the dietary F supply as well as on skeletal F concentration. Fasting and post-ingestion or postinjection plasma F levels have been determined in rats on F doses that cause different degrees of enamel fluorosis. The results indicate that temporary peak values rather than elevated fasting values are responsible for the occurrence of enamel fluorosis and that the peak values must approach about 10 μM in order to block enamel formation by the ameloblasts. The diagnostic and prognostic importance of plasma F determinations is discussed.
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  • 6
    ISSN: 1432-2048
    Keywords: Bryophyllum ; Circadian rhythm ; CO2 output ; Phytochrome ; Red light ; Rhythm (circadian)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rhythm of carbon dioxide output in Bryophyllum leaves was entrained on exposure to 0.25 h of white light every 24 h. Entrainment also occurred on similar exposure to monochromatic radiation in spectral bands centred at 660 nm and, to a lesser extent, at 730 nm, but a band centred at 450 nm was without effect. A “skeleton” irradiation programme comprising two 0.25-h exposures to white light per 24 h also entrained the rhythm when the intervening dark periods were either 7.5 h and 16 h, or 10.5 h and 13 h. The rhythm disappeared when the two exposures were separated by 11.5-h and 12-h dark periods. Regular 0.25-h exposures to red light separated by 11.75-h periods of darkness also resulted in loss of the rhythm. Red/far-red reversibility was observed in irradiation schedules having either one or two exposures to red light daily. In the latter case, far-red reversal of the effects of one of the exposures to red light resulted in entrainment of the rhythm by the other, instead of abolition of the rhythm. The occurrence of distinct red/far-red reversibility suggests strongly that phytochrome is the pigment involved in entrainment of this rhythm by cycles of light and darkness.
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  • 7
    Electronic Resource
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    Springer
    Planta 133 (1977), S. 169-177 
    ISSN: 1432-2048
    Keywords: Cell fractionation ; Cucurbita ; Histochemical staining ; Phosphotungstate-chromate staining ; Phytochrome ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphotungstic acid-chromic acid (PTA-CrO3) stain, putatively specific for the plasma membrane of plants, has been used in an attempt to monitor the distribution of this membrane in a 20,000 x g particulate fraction from Cucurbita hypocotyl hooks. On discontinuous sucrose gradients, the relative distributions of the phytochrome and PTA-CrO3-positive vesicles present in this fraction appear to be correlated. When intact tissue is stained, however, other components, in addition to the plasma membrane, react positively to the stain. These components include prolamellar-body membranes, lipid droplets, and ribosomes. This lack of specificity calls into question the reliability of the technique for the unequivocal identification and accurate quantitation of plasma-membrane fragments in isolated particulate fractions. The present data do not, therefore, provide unambiguous evidence that phytochrome is associated with plasma membrane in tissue homogenates from Cucurbita.
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  • 8
    Electronic Resource
    Electronic Resource
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    Planta 134 (1977), S. 11-16 
    ISSN: 1432-2048
    Keywords: Brassica ; Chlorophyll ; Cotyledons ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytochrome determinations at 730/800 nm were performed on de-etiolated turnip (Brassica rapa L.) cotyledons in which chlorophyll (Chl) content had been reduced experimentally to varying degrees by pre-treatment with high temperature (HT), or transfer to 3% ethanol. The magnitude of detectable phytochrome depended on Chl content, showing a linear relationshop in vivo. The results were confirmed by an in vitro experiment where, however, the correlation was exponential. An attempt is made to illustrate phytochrome decay in continuous blue or red light after corretion for Chl interference. To overcome the possible objection that the higher Δ(ΔA) measured in continuous light after HT pre-treatment could be caused by a reduced rate of destruction, apparent re-synthesis following red light was measured after several hours of darkness during which time the HT effect was lost. Under these conditions HT pre-treated samples display a more realistic magnitude of apparent new synthesis and make correlation with a physiological response possible.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Planta 134 (1977), S. 57-59 
    ISSN: 1432-2048
    Keywords: Cell culture ; Clycine ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract No phytochrome can be detected spectrophotometrically in soybean (Glycine max (L.) Merr. cv. Mandarin) cell suspensions grown in darkness. White light from a tungsten filament lamp and a band of far-red light have been found to induce the appearance of phytochrome in them. Red light failed to bring about phytochrome increase and destroyed the phytochrome induced by far-red light.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Planta 135 (1977), S. 119-123 
    ISSN: 1432-2048
    Keywords: Chlorophyll ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurements of phytochrome by Δ (ΔA725–815 nm) were completely suppressed at chlorophyll concentrations of the order of 20–40 μg g-1 f.wt. in vivo and 37 μg cm-3 in vitro, and the readings were reduced by 50% at only 12 μg cm-3 in vitro. At these concentrations of chlorophyll in aqueous methanol, the loss of phytochrome signal in vitro appeared to be due to failure of phytochrome photoconversion rather than to interference with ΔA measuremebt by chlorophyll fluorescence in the 125/815 nm measuring beam.
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