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  • 11
    Digitale Medien
    Digitale Medien
    Prediction of the competitive effects of weeds on crop yields based on the relative leaf area of weeds (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 36 (1996), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: For implementation of simple yield loss models into threshold-based weed management systems, a thorough validation is needed over a great diversity of sites. Yield losses by competition wsth Sinapis alba L. (white mustard) as a model weed, were studied in 12 experiments in sugar beet (Beta vulgaris L.) and in 11 experiments in spring wheat (Triticum aestivum L.). Most data sets were heller described by a model based on the relative leaf area of the weed than by a hyperbolic model based on weed density. This leaf area model accounted for (part of) the effect of different emerging times of the S. alba whereas the density model did not. A parameter that allows the maximum yield loss to be smaller than 100% was mostly not needed to describe the effects of weed competition. The parameter that denotes the competitiveness of the weed species with respect to the crop decreased the later the relative leaf area of the mustard was determined. This decrease could be estimated from the differences in relative growth rate of the leaf area of crop and S. alba. However, the accuracy of this estimation was poor. The parameter value of the leaf area model varied considerably between sites and years. The results strongly suggest that the predictive ability of the leaf area model needs to be improved before it can be applied in weed management systems. Such improvement would require additional information about effects of abiotic factors on plant development and morphology and the definition of a time window for predictions with an acceptable level of error.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3180.1996.tb01805.x
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  • 12
    Digitale Medien
    Digitale Medien
    Changes in the abundance of weeds in spring cereal fields in Finland (2003)
    Oxford, UK : Blackwell Science Ltd
    Weed research 43 (2003), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The data of two weed surveys of spring cereals (conducted in 1982–84 and 1997–99) in Finland were applied to study changes in the total abundance (the number of individuals and dry weight) of the weed community as well as in the abundance and frequency of occurrence of single species. The estimated overall mean for the differences in total dry weight was 31.1 kg ha−1 and the differences in the total number of individuals was 46.6 individuals m−2 with higher numbers in the 1990s. Most of the overall variability in dry weight (63%) and in number of individuals (57%) was attributable to variability between fields within the same farm. None of the environmental variables could explain the variability in the difference in dry weight, or in the number of individuals between decades. Descriptive analysis of the single species data revealed a higher abundance and frequency of occurrence of most species in the 1990s than in the 1980s. No statistically significant differences were detected in the number of individuals of species tolerant of sulfonylureas (pooled data on Galium spurium and Viola arvensis) between decades. The results are discussed in relation to changes in the use of herbicides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3180.2003.00351.x
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  • 13
    Digitale Medien
    Digitale Medien
    Efficacy of chemical weed control in spring cereals in Finland (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 28 (1988), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: A national survey was conducted in Finland from 1982 to 1984 to determine the main weed species in spring cereals and the efficacy of herbicides on Finnish farms. The most common dicotyledonous weeds producing the highest biomass in spring cereals were Chenopodium album L., Galeopsis spp. L., Stellaria media (L.) Vill. and Lapsana communis L. The main grass weed was Elymus repens (L.) Gould. The average reduction of weed biomass by herbicide treatment was 75%. More reliable efficacy was obtained with herbicide mixtures than with MCPA alone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3180.1988.tb00800.x
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  • 14
    Digitale Medien
    Digitale Medien
    Immunohistochemical localization of epithelial cells expressing transferrin receptors in normal and diseased human dento-gingival junction (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 23 (1988), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The rate of cell proliferation, which is associated with the density of transferrin receptors on the cell surface, may have an effect on the homeostasis of epithelial cell populations in the dento-gingival junction. In addition to moderate labeling of basal cells, intensive labeling of transferrin receptors was found on suprabasal cells of sulcular epithelium towards the gingival margin of healthy tissues. In contrast, biopsies from diseased tissue exhibited increased labeling towards the base of the pocket. This distribution of labeling suggests that the distinct suprabasal population of cells expressing the transferrin receptors is associated with the process of pocket formation. The density of transferrin receptors decreased towards the lamina propria of gingiva and towards the apical termination of the junctional epithelium. In samples from periodontal pockets, the number of receptors was high eveo in the germinative cell layers. Labeled cells were also demonstrated in crevicular washings. The washing method together with the demonstration of transferrin receptors may provide a new approach for the study of epithelial cell homeostasis in the dento-gingival tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1988.tb01355.x
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  • 15
    Digitale Medien
    Digitale Medien
    Lactoferrin impedes epithelial cell adhesion in vitro (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 33 (1998), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: In the process of host defence against microbial challenge, neutrophils release granule contents with the potential side effect of damaging structural tissues. In the junctional epithelium such damage may contribute to the degeneration and renewal of the epithelial cells attached directly to the tooth (DAT cells), and subsequently to periodontal pocket formation. This study reports on lactoferrin, one of the substances released by neutrophils, and its effects on epithelial cell adhesion, growth, DNA synthesis and spreading of cell colonies at concentrations recorded in the crevicular fluid. We show that, in opposition to what has been reported on bacterial cells, lactoferrin has no effect on the DNA synthesis of attached epithelial cells in model systems attempting to simulate the DAT cells in vivo. However, both iron-saturated and unsaturated lactoferrin hampered cell adhesion, growth and spreading of cell colonies in a dose-dependent manner. These findings suggest that lactoferrin does not affect epithelial cell proliferation but it may have a role in delaying the repair of the DAT cell population during inflammation by interfering with cell adhesion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1998.tb02286.x
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  • 16
    Digitale Medien
    Digitale Medien
    Bacterial metabolites sodium butyrate and propionate inhibit epithelial cell growth in vitro (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 32 (1997), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The structural and functional barrier preventing the free advancement of microbial plaque subgingivally along the tooth surface is formed by the junctional epithelial (JE) cells directly attached to the tooth (DAT cells). The mechanism leading to degeneration of the DAT cells is not known. In the present study we examined the possible role of short chain fatty acids (SCFAs) on epithelial cells by making use of 2 epithelial cell cultures (HaCaT and ERM) and an explant culture model of human JE. The SCFAs butyrate and propionate were used in concentrations found in human plaque and gingival crevicular fluid (0.25–16.0 mM). The SCFAs had no effect on primary cell adhesion nor on the epithelial attachment apparatus (EAA). By contrast, even 0.25 mM of butyrate significantly retarded epithelial cell growth. Similar effects with propionate were first observed at concentrations higher than 1.0 mM. The retardation of epithelial cell growth was found to be due to inhibition of cell division. Furthermore, after butyrate treatment dense accumulations of intermediate filaments and cytoplasmic vacuolization were characteristically seen in cells adjacent to cells of normal appearance. This suggests that some cells of the growing epithelial cell population are more sensitive to the SCFAs than others, and agrees with previous reports on the DAT cells of periodontally-involved teeth in vivo. The results suggest that SCFAs are microbial factors that play a role in the initiation and progression of periodontal pocket formation by impairing epithelial cell function rather than having a direct effect on the EAA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1997.tb00541.x
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  • 17
    Digitale Medien
    Digitale Medien
    Proliferative potential of the attached cells of human junctional epithelium (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 29 (1994), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Samples of the attached cells of junctional epithelium (DAT cells) were obtained during extractions of eight erupted bicuspids from young healthy subjects. Each extracted tooth, with its layer of living DAT cells, was incubated for three hours in minimum essential medium (MEM) containing 5 μCi/ml of 3H-thymidine, and prepared for autoradiography. An average of 3 labeled cells per 1 mm of the epithelial attachment was found along the vertical dimension of the tooth. The attachment of an individual cell to the tooth surface was found to be a prerequisite for the cell's DNA synthesis suggesting that the tooth has a nonspecific epigenetic role in defining the functional phenotype of the DAT cells. Even the most coronal DAT cells located about 200 μm apical from the plaque border, were found to synthesize DNA. The finding suggests that mechanisms which regulate the multiplication of DAT cells are involved in the preservation of the integrity of the dentogingival junction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1994.tb01089.x
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  • 18
    Digitale Medien
    Digitale Medien
    An attempt to simulate junctional epithelium of human gingiva in vitro (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 18 (1983), S. 0 
    Details
    ISSN: 1600-0765
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Pieces of human masticator mucosa were maintained in a Trowell-type organ culture. The explants were placed on their side on either microporous filters or decalcified dentin matrix slices. The presence of serum in the culture medium enhanced epithelial outgrowth (epibolus) from the explants. The epibolus grew longer in contact with the substratum than along the free connective tissue surface of the explant.When grown on microporous filters, the flow of migrating cells was directed between the explant and substratum. As a sign of epithelial attachment to the filter, a structure morphologically similar to basal lamina and hemidesmosomes was seen. The decalcified dentin matrix, however, caused the epithelial cells to migrate outwards from the explant. The explants became loosely attached to the matrix. Although some electron-dense material was secreted into the contact area, a typical basal lamina was not seen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0765.1983.tb00365.x
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  • 19
    Digitale Medien
    Digitale Medien
    Comparison of different methods in microstructural characterization of porous silicon (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 504-506 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Results obtained using the Brunauer-Emmett-Teller method, small-angle x-ray scattering and wide angle x-ray diffraction in the study of porous silicon are compared. The BET method seems to fail when the porosity of samples is smaller than 50%, giving unrealistically large values for the specific surface area, but giving results similar to SAXS when the porosity is larger than 50%. In the comparison of the WAXD and SAXS data quite large differences between the average particle size and chord length were observed in low-porosity samples. The possible origin of the differences is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889899014466
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  • 20
    Digitale Medien
    Digitale Medien
    Comparison of two doses of betaxolol and placebo in hypertension: A randomized, double-blind cross-over trial (1982)
    Springer
    European journal of clinical pharmacology 23 (1982), S. 491-494 
    Details
    ISSN: 1432-1041
    Schlagwort(e): betaxolol ; hypertension ; double-blind trial ; cross-over trial
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Betaxolol is a cardioselective beta-blocker, which has a bioavailability of 90% and a T1/2 of 20 h. A four group, cross-over double-blind trial was conducted to select between betaxolol 20 mg and 40 mg for long term trials. 60 patients were allocated randomly to one of the sequences placebo-20 mg, 20 mg-placebo, placebo-40 mg and 40 mg-placebo, each treatment lasting for 2 weeks. Groups were homogenous for baseline diastolic blood pressure (DBP), age and male/female ratio, and were slightly unbalanced for weight. A two-way ANOVA (3 treatments, 2 sequences) showed no treatment-sequence interaction nor sequence effect. The mean reduction in DBP was 14.2±1.8 mm Hg following 20 mg and 18.0±1.8 following 40 mg betaxolol, and 4.0±1.2 mm Hg during placebo (p〈0.001). Age, weight, baseline DBP and duration of hypertension did not influence the treatment effect. The 95% confidence intervals of the reduction in DBP were 10.4–17.9 for 20 mg and 14.3–21.6 mm Hg for betaxolol 40 mg. Aiming at a mean reduction to 90 mm Hg, betaxolol 20 mg would appear to be adequate in similar patient populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00637494
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