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  • bioavailability  (38)
  • Zea mays  (36)
  • Springer  (74)
  • International Union of Crystallography
  • 2005-2009
  • 1995-1999  (39)
  • 1980-1984  (35)
  • 1965-1969
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  • 1
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of zimelidine (1980)
    Springer
    European journal of clinical pharmacology 17 (1980), S. 111-116 
    Details
    ISSN: 1432-1041
    Keywords: zimelidine ; norzimelidine ; antidepressants ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The systemic availability of a new antidepressant, zimelidine, and of its pharmacologically active metabolite, norzimelidine, was studied in six healthy male volunteers. Three single doses of zimelidine (25 mg and 100 mg orally and 25 mg i.v.) and two single doses of norzimelidine (25 mg orally and i. v.) were given to each volunteer allowing at least seven days between administrations. Plasma concentrations of zimelidine and norzimelidine were determined in serial blood samples by HPLC. Following oral zimelidine peak plasma concentrations of the metabolite were attained about 3 h after dosing. Oral administration of norzimelidine itself resulted in a plasma concentration profile for this compound that was similar to that observed after oral zimelidine. Utilising the plasma concentration data following intravenous infusion of each compound, the elimination half-lives for zimelidine and norzimelidine were calculated to be 5.1 h (range 4.3–6.0) and 15.5 h (range 10.6–22.9) respectively. The total body clearances of the 2 compounds were similar at 0.52 l · min−1 (range 0.26–0.70) for zimelidine and 0.56 l · min−1 (range 0.28–0.83) for norzimelidine. The substantially longer elimination half-life of norzimelidine was apparently the result of a larger volume of distribution (9.4 l · kg−1; range 7.8–11.4) for this metabolite, as compared to zimelidine (3.21 · kg−1; range 1.6–4.9). The calculated bioavailability of zimelidine was 26% (range 9.1–39) after the 25 mg oral dose, and 29% (range 14–46) after the 100 mg dose. The bioavailability of norzimelidine was 66% (range 36–91). However, oral administration of zimelidine resulted in as much or more norzimelidine reaching the systemic circulation, as the oral administration of norzimelidine itself. This is important as a large part of the activity of the drug may be due to the metabolite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562618
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  • 2
    Electronic Resource
    Electronic Resource
    Crop yield and tree-leaf production in three planting patterns of temperate-zone alley cropping in Oregon, USA (1999)
    Springer
    Agroforestry systems 46 (1999), S. 273-288 
    Details
    ISSN: 1572-9680
    Keywords: A,nus rubra ; hedgerow intercropping ; Robina pseudoacacia ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to determine crop and tree productivity in several alley cropping planting patterns. The four- year study was conducted in western Oregon, United States and involved irrigated sweet corn (Zea mays) intercropped between hedgerows of red alder (Alnus rubra) and black locust (Robina pseudoacacia). Three alley cropping planting patterns with variable plant populations and tree-crop proximity were tested with each tree species in a randomized block design. Space available to trees and crops determined yield of both plant components. High crop yield coincided with low pruning yield, and vice versa. Compared to monocropping, yield reductions in traditional alley cropping planting patterns with widely spaced, double tree rows ranged from 5% to 15%. A. rubra and R. pseudoacacia coppiced readily and produced 0.9 to 4.7 tons of dry matter pruning biomass per growing season, depending on planting pattern and year. A. rubra yield continually increased during the trial, while the ability of R. pseudoacacia to produce green manure after frequent coppicing appeared to weaken. After four years, soil organic matter was 4 to 7% higher in the topsoil of an alley cropping system compared to a monocropping system. However, continuous growing of sweet corn resulted in decreased soil organic matter levels in both cropping systems compared to original levels. Crop yield reductions and the need for additional management inputs constrain the implementation of alley cropping in temperate climates. Only if benefits other than minor soil fertility improvements are realized is alley cropping a feasible alternative in temperate climate regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006204018212
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of calcium, magnesium, potassium and boron on sperm cells isolated from pollen of Zea mays L. (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 113-122 
    Details
    ISSN: 1432-2145
    Keywords: Zea mays ; Calcium ; Cell integrity ; Cell viability ; Sperm cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Our previous studies showed that Brewbaker and Kwack salts, which have been widely used in pollen germination and sperm isolation, are not appropriate for the maintenance of isolated maize (Zea mays L.) sperm cells. In the present study, we have characterized the effects of each BKS component salt on the integrity of isolated sperm cells using hemacytometry. At 0.01 and 0.1 mM, there were no differences in cell number between control and any salt-treated cells except a 22% decrease with 0.1 mM MgSO4 at 48 h. At the 1 mM level, cell number decreased with time in the presence of Ca(NO3)2 and MgSO4, with loss of integrity of most cells at 48 h, while KNO3 and H3BO3 had little or no effect. Further characterization of calcium-induced reduction in cell integrity using flow cytometry showed that depletion of possible residual free calcium by addition of EGTA to the suspension medium improved cell longevity and viability. Exposure of isolated sperm cells to 1 mM calcium had no effect on cell integrity and viability in 5 h; however, only 12% of cells remained intact at 24 h. The reduction in cell integrity was hastened when cells were pretreated with the calcium ionophore A23187 prior to exposure to 1 mM calcium, with a 54% reduction in cell number at 1 h and complete cell lysis at 24 h. However, depletion of cytosolic free calcium by pretreatment of cells with the calcium ionophore followed by resuspension in the presence of EGTA resulted in rapid reduction of cell integrity as well. These results collectively suggest that maize sperm cells are sensitive to exogenous free calcium; however, a certain level of cytosolic free calcium is necessary for maintenance of integrity. Mechanisms of calcium-induced reduction in cell integrity are discussed along with possible roles of the sensitivity of sperm cells to calcium in fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230898
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of medigoxin in outpatients (1981)
    Springer
    European journal of clinical pharmacology 19 (1981), S. 251-258 
    Details
    ISSN: 1432-1041
    Keywords: medigoxin ; digoxin ; dissolution rate ; proportionality ; bioavailability ; prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We compared our ability to predict the dose of medigoxin and of digoxin required to achieve a fixed serum concentration (the dose requirement) in 33 outpatients. Preliminary work supported the assumptions that the steady state glycoside concentration achieved was proportional to the daily dose given to an individual, and that the bioavailability of the different tablet presentations was similar for either glycoside. We were not able to predict the dose requirement from patient characteristics with any more certainty for medigoxin than for digoxin. Not only the between-patient variability in dose requirement, but also the within-patient variability, was similar for the two glycosides. However the digoxin used had a dissolution rate of over 90% in 1 h. When comparing medigoxin with digoxin of lower, or more variable dissolution rate, medigoxin may be preferable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562801
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  • 5
    Electronic Resource
    Electronic Resource
    Bioavailability and diurnal variation in absorption of sustained release theophylline in asthmatic children (1983)
    Springer
    European journal of clinical pharmacology 25 (1983), S. 667-672 
    Details
    ISSN: 1432-1041
    Keywords: theophylline ; asthma ; children ; sustained-release ; diurnal ; absorption ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absolute oral bioavailability of a sustained release theophylline tablet (Nuelin-SR250), given 12 hourly was determined in 14 asthmatic children aged 5 to 13 years. In 4 of the patients, mean bioavailability of the fourth dose was 38.9±8.4% and that of the sixth dose was 67.9±25.9% (p〈0.05) in the other ten patients. This suggests steady-state had not been achieved after four doses. In the initial study with 9 patients, a significant diurnal variation in predose plasma theophylline concentrations was observed, as the mean morning predose concentrations were 2.9 fold greater than the mean evening predose concentrations (p〈0.005). Dual peak plasma concentrations occurred in 5 out of the 9 patients. The mechanism of this diurnal variation was investigated in a further 5 asthmatic children (10.8 years ±1.6). Morning and night steady-state plasma theophylline concentrations during a continuous intravenous infusion of aminophylline were not different (14.9±5.3 mg/l vs. 15.6±5.9 mg/l), demonstrating that there was no diurnal variation in the plasma clearance of theophylline. The diurnal variation in predose concentrations with Neulin-SR250 was confirmed with the morning concentrations again being 2.6 fold greater than those in the evening. However, bioavailability was not significantly different for day (09.00–21.00) and night (21.00–09.00) dosing intervals after doses 6 and 7 respectively of Nuelin-SR250. The plasma concentration versus time profiles suggested that the diurnal variation in predose concentrations was due to slower absorption of the evening dose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542356
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  • 6
    Electronic Resource
    Electronic Resource
    Detection of the apomictic mode of reproduction in maize-Tripsacum hybrids using maize RFLP markers (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 1198-1203 
    Details
    ISSN: 1432-2242
    Keywords: Diplospory ; RFLP ; Bulk-segregant analysis ; Genome similarity ; Intergeneric hybrids ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polyploid plants in the genus Tripsacum, a wild relative of maize, reproduce through gametophytic apomixis of the diplosporous type, an asexual mode of reproduction through seed. Moving gene(s) responsible for the apomictic trait into crop plants would open new areas in plant breeding and agriculture. Efforts to transfer apomixis from Tripsacum into maize at CIMMYT resulted in numerou intergeneric F1 hybrids obtained from various Tripsacum species. A bulk-segregant analysis was carried out to identify molecular markers linked to diplospory in T. dactyloides. This was possible because of numerous genome similarities among related species in the Andropogoneae. On the basis of maize RFLP probes, three restriction fragments co-segregating with diplospory were identified in one maize-Tripsacum dactyloides F1 population that segregated 1∶1 for the mode of reproduction. The markers were also found to be linked in the maize RFLP map, on the distal end of the long arm of chromosome 6. These results support a simple inheritance of diplospory in Tripsacum. Manipulation of the mode of reproduction in maize-Tripsacum backcross generations, and implications for the transfer of apomixis into maize, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222943
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  • 7
    Electronic Resource
    Electronic Resource
    Chromosomal location of the catalase structural genes in Zea mays using B-A translocations (1980)
    Springer
    Theoretical and applied genetics 58 (1980), S. 211-218 
    Details
    ISSN: 1432-2242
    Keywords: B-A translocations ; Catalase Mapping ; Structural genes ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary B-A translocations have been used to map the catalase genes, Cat1, Cat2, and Cat3 of Zea mays. Cat1 was found to be on the short arm of chromosome 5, 9.1 map units from brittle endosperm (bt 1). Cat2 was located on chromosome 1S, while Cat3 was located on the distal half of chromosome 1L. There was no linkage between Cat2 and Cat3. The significance of mapping the catalase structural genes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288439
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  • 8
    Electronic Resource
    Electronic Resource
    Pharmacokinetics and bioavailability of intravenous, oral, and rectal nitrazepam in humans (1982)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 10 (1982), S. 231-245 
    Details
    ISSN: 1573-8744
    Keywords: nitrazepam ; i.v. ; oral ; rectal administration ; protein binding ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and bioavailability of nitrazepam following intravenous, oral (tablet), and rectal (solution) administration were studied in seven healthy, young male volunteers. Nitrazepam plasma concentrations were determined by electron-capture GLC; pharmacokinetic evaluations were made by compartmental analysis (NONLIN) and compared with the results obtained by a less stringent modelling of the data. The plasma concentration-time profile was similar for all three routes of administration. Mean kinetic parameters as obtained by compartmental analysis of i.v. nitrazepam were: distribution half-life 17 min; volume of distribution after equilibrium 2.14 liters/kg; total plasma clearance 61.6 ml/min; elimination half-life 29.0 h. The mean protein unbound fraction of nitrazepam in plasma was 12.3% and the clearance of the unbound fraction was 506 ml/min. Absorption of oral nitrazepam started after the elapse of a lag time (mean value 12 min) and occurred as an apparent first-order process in all but one subject, with a mean absorption half-life of 16 min. Distribution and elimination half-lives were comparable with those following i.v. administration. Following rectal administration of the nitrazepam solution, rapid first-order absorption occurred with a mean lag time of 4 min and a mean absorption half-life of 9 min. Peak times (median 18 min) were significantly shorter than following oral administration (median 38 min), but there was little difference in peak concentrations. The distribution half-life was similar to i.v. and oral administration, but the elimination half-lives were longer with a mean value of 33.1 h. Following i.v. administration a good agreement was found between the results obtained by compartmental analysis using NONLIN and those obtained by a less stringent modelling of the data. Following oral and rectal administration, a good agreement between the two procedures was found for the elimination half-life; estimation of bioavailability, however, was higher by compartmental analysis. The mean bioavailability data showed that absorption is complete when nitrazepam is given orally and almost 20% lower when it is given rectally, but considerable interindividual differences were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059259
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  • 9
    Electronic Resource
    Electronic Resource
    Aflatoxin contamination caused by natural fungal infection of preharvest corn (1980)
    Springer
    Plant and soil 54 (1980), S. 469-475 
    Details
    ISSN: 1573-5036
    Keywords: Aflatoxin ; Aspergillus flavus ; Corn ; Fungi Maize ; Mycotoxins ; Naturally-occurring toxins ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Aflatoxin contamination of developing corn (Zea mays L.) kernels caused by natural infection byAspergillus flavus Link ex Fries was studied in hybrids developed for the U.S. corn belt and for the southern U.S. and grown at diverse locations in 1977. Planting dates were staggered to examine the effect of crop maturity on infection by the toxin-producing fungus. A broad range of toxin values was observed at harvest; some levels exceeded the highest that had been previously recorded in corn. The highest concentration of aflatoxin B1 detected was 8030 ppb. Levels of toxin differed significantly among planting dates in Florida and Georgia; the second planting date at these locations contained the highest toxin levels. Elevated concentrations of toxin were characteristic of kernel samples from southern locations and southeast Missouri; at these locations samples from hybrids developed for the south had significantly lower levels of toxin than hybrids developed for the corn belt. Ears with heavy insect damage had higher toxin levels than ears with less evidence of insect attack.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181839
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  • 10
    Electronic Resource
    Electronic Resource
    Aflatoxin accumulation in preharvest maize kernels: Interaction of three fungal species, european corn borer and two hybrids (1982)
    Springer
    Plant and soil 65 (1982), S. 95-102 
    Details
    ISSN: 1573-5036
    Keywords: Aflatoxin ; Aspergillus flavus ; Zea mays ; Ostrinia nubilalis ; Mycotoxins ; Naturally-occurring toxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The interaction was studied among: 1) developing maize kernels (Zea mays L.); 2) European Corn Borer (ECB) (Ostrinia nubilalis Hubner); 3) and three fungal species,Aspergillus flavus Lk. ex Fr.,Penicillium oxalcium Currie and Thom, andFusarium moniliforme Sheld. Two hybrids with varying degrees of resistance to ECB stalk damage were grown in Iowa, Georgia, and Missouri in 1980. One-half of the plots were hand-infested with ECB egg masses. Fungal spores of individual isolates or combinations of the three species were introduced into the silk channels of developing ears in designated plots. ECB larvae were subsequently collected from developing ears. A higher incidence ofA. flavus group isolates was observed in ECB larvae collected from ears that had been inoculated withA. flavus than from insects collected from control ears. Although the resistant hybrid exhibited reduced ECB stalk damage compared with the susceptible variety, no consistent pattern of hybrid effect on the association betweenA. flavus and ECB was observed at all three locations. Differences in aflatoxin B1 levels in mature kernels from the three locations ranged from 8 ppb in Iowa samples to 419 ppb in Missouri kernels. Conditions during crop development at the Missouri location were particularly conducive to elevated presence ofA. flavus propagules in ECB larvae, increased ECB-mediated stalk damage, and greater toxin concentration in mature kernels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02376807
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