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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 93 (1986), S. 75-83 
    ISSN: 1432-1424
    Keywords: single channel ; chloride ; selectivity ; conductance state ; Aplysia neurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Single-channel recordings from outside-out patches ofAplysia neurones in K-free solutions revealed the presence in most membrane patches of ionic channels showing surprising selectivity properties, as deduced from reversal potential measurements. After complete substitution of external NaCl by mannitol (in the presence of internal CsCl), these channels are more permeable to Cl than to Cs, but are also slightly permeable to Cs:P Cl/P Cs=4. Furthermore, in the presence of external NaCl, their ability to discriminate cations from anions seems lower than in external mannitol. Substitutions of external Cl by various anions showed that the channels are more permeable to NO3 than to Cl, and that they are appreciably permeable to isethionate, SO4 and methanesulfonate. Their elementary conductance is about 100 pS in 600mm symmetrical Cl. However, different conductance states (usually 2 or 3) can often be detected in the same membrane patch. By using voltage ramps, we established theI–V curves corresponding to each of these states and found small but significant differences between the reversal potentials of each state.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 227 (1989), S. 114-117 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Systemically administered fluorescein (F) is rapidly transformed to the fluorescent metabolite fluorescein glucuronide (FG). Little is known about how diseases can influence the synthesis or disposition of FG. We studied F and FG in the plasma ultrafiltrate of 75 people who were normal or had diabetes, retinitis pigmentosa, or idiopathic rhegmatogenous retinal detachment. F and FG were determined by high-performance liquid chromatography. The concentration of FG was comparable to F 1 h after an intravenous injection of F, both in normal subjects and in patients with retinitis pigmentosa, which suggests that FG may not be an important contributor to the vitreous fluorescence at that time. At later times FG substantially exceeded F. The concentration of FG was significantly higher in diabetics than in the other groups 14 h after an oral dose of F. Accordingly, the possible effect of disease on plasma dye concentrations should be considered in studies measuring F by fluorescence hours after systemic F administration, since this could influence the intraocular fluorescence irrespective of any alteration in ocular function.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of plant growth regulation 5 (1986), S. 73-83 
    ISSN: 1435-8107
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A computer-based video digitizer system is described which allows automated tracking of markers placed on a plant surface. The system uses customized software to calculate relative growth rates at selected positions along the plant surface and to determine rates of gravitropic curvature based on the changing pattern of distribution of the surface markers. The system was used to study the time course of gravitropic curvature and changes in relative growth rate along the upper and lower surface of horizontally-oriented roots of maize (Zea mays L.). The growing region of the root was found to extend from about 1 mm behind the tip to approximately 6 mm behind the tip. In vertically-oriented roots the relative growth rate was maximal at about 2.5 mm behind the tip and declined smoothly on either side of the maximum. Curvature was initiated approximately 30 min after horizontal orientation with maximal (50°) curvature being attained in 3 h. Analysis of surface extension patterns during the response indicated that curvature results from a reduction in growth rate along both the upper and lower surfaces with stronger reduction along the lower surface.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 4 (1980), S. 263-266 
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have confirmed that doxorubicin induces irreversible changes in the nucleolar ultrastructure of myocardial cells of rats. Similar changes were not caused by an equal dose of the synthetic analogue, 5-iminodaunomycin. These results combined with previous and current comparative tests with this analogue, doxorubicin, and daunomycin suggest that 5-iminodaunomycin may serve as a less cardiotoxic anthracycline derivative.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1750
    Keywords: Epidermal growth factor ; Platelet derived growth factor ; Inhalation injury ; Tracheal repair process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Toxic gases and fumes have been shown to be injurious to the upper airways. Repair of this injury involves proliferation and migration of surviving nonciliated cells, followed by differentiation to a normal phenotype. Because recent results suggested that growth factors could improve the outcome of an airway injury, we undertook this study to determine the efficacy of these materials as an initial treatment to accelerate the healing process. In 24 anesthetized sheep, a portion of the trachea was exposed to smoke from smouldering cotton cooled to 37°C. Twelve received aerosolized epidermal growth factor plus platelet derived growth factor, while twelve received placebo. At 10 days after injury, nonciliated and ciliated cells were totally absent in the injured trachea receiving the placebo. In animals receiving growth factors, nonciliated and ciliated cells, however, were present (56% and 31% of uninjured trachea, respectively). At 13 days after injury, nonciliated and ciliated cell counts in those receiving placebo were 67% and 33% of uninjured, respectively. In sheep receiving growth factors, tracheal nonciliated and ciliated cell counts had increased to 105% and 64% of uninjured trachea, respectively. We conclude that growth factors therapy after airway injury stimulates cell proliferation and differentiation, and this therapeutic intervention to accelerate the repair process in acute airway injury is an approach applicable to humans.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1750
    Keywords: Tracheal epithelium ; Cell regeneration ; Basal cells ; Ciliated cells ; Toxic smoke injury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cellular repair process of injured tracheal epithelium is described for sheep after exposure to toxic smoke containing high concentrations of acrolein. Fourteen fasted 3–4-year-old ewes had a portion of their cervical trachea exposed to cotton smoke for 20 min and then were sacrificed at various time intervals ranging from 1 to 22 days after exposure. Within 1 day of injury, columnar epithelium sloughed intact from the trachea with a concomitant reduction of nearly 35% in the basal cell population. At 2 days of recovery, the cellularity of the epithelium had increased and mitotic figures were observed in some tracheal epithelial and gland cells. By 8 days, undifferentiated hyperplastic cells increased to 30/100 µm, differentiated nonciliated columnar cells first appeared, and the basal cell population returned to a normal count of 13 cells/100µm. Thirteen days after exposure, the undifferentiated hyperplastic cell population had declined to 7 cells/100/ µm, nonciliated columnar cells were at control values, and some ciliated cells were identified. At 18 and 22 days, epithelium was normal in appearance and the count was 13 cells/100µm. Data suggest that because the columnar epithelium sloughs intact with the cilia remaining active, toxic smoke may affect their attachment to the basal lamina. Furthermore, the regeneration process involves differentiation of hyperplastic cells in which they elongate down to the basal lamina, thus re-establishing the integrity of tall, epithelium in the sheep trachea.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 83 (1996), S. 97-102 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 83 (1996), S. 97-102 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Notes: 10 Be concentration. This pedogenic component closely parallels paleorainfall, so that regional precipitation history during the Quaternary can be derived.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 315 (1980), S. 63-67 
    ISSN: 1432-1912
    Keywords: Phenytoin ; Methotrexate ; Anticonvulsants ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Administration of phenytoin for 5 days significantly reduces oral absorption and bone uptake of radiolabelled calcium in mice. Acute treatment with phenytoin had no effect on calcium disposition. Pretreatment (1–5 days) with phenobarbital also had no effect of calcium disposition. Methotrexate pretreatment for 5 days increased the bone uptake of radiolabelled calcium presumably by decreasing calcium renal clearance. It is concluded that phenytoin induced reduction in calcium metabolism is unrelated to a state of functional folate deficiency.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Planta 183 (1991), S. 381-390 
    ISSN: 1432-2048
    Keywords: Digitizer ; Gravitropism (root, digitizer analysis) ; Growth (root) ; Root (gravitropism, growth) ; Zea (root gravitropism)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used a video digitizer system to measure surface extension and curvature in gravistimulated primary roots of maize (Zea mays L.). Downward curvature began about 25 ± 7 min after gravistimulation and resulted from a combination of enhanced growth along the upper surface and reduced growth along the lower surface relative to growth in vertically oriented controls. The roots curved at a rate of 1.4 ± 0.5° · min−1 but the pattern of curvature varied somewhat. In about 35% of the samples the roots curved steadily downward and the rate of curvature slowed as the root neared 90°. A final angle of about 90° was reached 110 ±35 min after the start of gravistimulation. In about 65% of the samples there was a period of backward curvature (partial reversal of curvature) during the response. In some cases (about 15% of those showing a period of reverse bending) this period of backward curvature occurred before the root reached 90°. Following transient backward curvature, downward curvature resumed and the root approached a final angle of about 90°. In about 65% of the roots showing a period of reverse curvature, the roots curved steadily past the vertical, reaching maximum curvature about 205 ± 65 min after gravistimulation. The direction of curvature then reversed back toward the vertical. After one or two oscillations about the vertical the roots obtained a vertical orientation and the distribution of growth within the root tip became the same as that prior to gravistimulation. The period of transient backward curvature coincided with and was evidently caused by enhancement of growth along the concave and inhibition of growth along the convex side of the curve, a pattern opposite to that prevailing in the earlier stages of downward curvature. There were periods during the gravitropic response when the normally unimodal growth-rate distribution within the elongation zone became bimodal with two peaks of rapid elongation separated by a region of reduced elongation rate. This occurred at different times on the convex and concave sides of the graviresponding root. During the period of steady downward curvature the elongation zone along the convex side extended farther toward the tip than in the vertical control. During the period of reduced rate of curvature, the zone of elongation extended farther toward the tip along the concave side of the root. The data show that the gravitropic response pattern varies with time and involves changes in localized elongation rates as well as changes in the length and position of the elongation zone. Models of root gravitropic curvature based on simple unimodal inhibition of growth along the lower side cannot account for these complex growth patterns.
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