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  • 1
    Electronic Resource
    Electronic Resource
    Inhibitory and Stimulatory Effects of Prostaglandins on Osteoclast Differentiation (1997)
    Springer
    Calcified tissue international 60 (1997), S. 63 -70 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Osteoclast — Differentiation — Bone resorption — Prostaglandins.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The effect of prostaglandins (PGs) on osteoclast differentiation, an important point of control for bone resorption, is poorly understood. After an initial differentiation phase that lasts at least 4 days, murine monocytes, cocultured with UMR106 osteoblastic cells (in the presence of 1,25-dihydroxyvitamin D3) give rise to tartrate-resistant acid phosphatase (TRAP) positive osteoclast-like cells that are capable of lacunar bone resorption. PGE2 strongly inhibits TRAP expression and bone resorption in these cocultures. To examine further the cellular mechanisms associated with this inhibitory effect, we added PGE2 to monocyte/UMR106 cocultures at specific times before, during, and after this initial 4-day differentiation period. To determine whether this PGE2 inhibition was dependent on the type of stromal cell supporting osteoclast differentiation, we also added PGE2 to cocultures of monocytes with ST2 preadipocytic cells. Inhibition of bone resorption was greatly reduced when the addition of PGE2 to monocyte/UMR106 cocultures was delayed until the fourth day of incubation; when delayed until the seventh day, inhibition did not occur. PGE2 inhibition of bone resorption was concentration-dependent and at 10−6 M was also mediated by PGE1 and PGF2α. In contrast to its effects on monocyte/UMR106 cocultures, PGE2 stimulated bone resorption in monocyte/ST2 cocultures. Both ST2 cells and UMR106 cells were shown to express functional receptors for PGE2. These results show that PGs strongly influence the differentiation of osteoclast precursors and that this effect is dependent not only on the type and dose of PG administered, but also on the nature of the bone-derived stromal cell supporting this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900187
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Some quantitative effects of indoleacetic acid on the wood production and tracheid dimensions of Picea (1977)
    Springer
    Planta 134 (1977), S. 223-228 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Cambium ; Gibberellin ; Picea ; Tracheids-wood production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diameter and wall thickness of tracheids produced after indoleacetic acid treatment were not significantly different from those of the intact controls, for the first few weeks after treatment of disbudded shoots of Picea abies Karst. and Picea sitchensis (Bong.) Carr. However, lateral application of indoleacetic acid (IAA) to intact shoots increased both tracheid diameter and wall thickness; it is suggested that IAA acted synergistically with another endogenous growth regulator, which was also removed by disbudding. Increase in wall thickness after exogenous IAA was associated with increase in duration of the wall thickening phase of tracheid differentiation; this is discussed in relation to the seasonal change from early to latewood. Cambial dormancy was induced by disbudding during active wood production. Since this occurred with or without the presence of current leaves, it is concluded that in Picea continued cambial activity depends upon supply of auxin from the buds, and cannot be supplied from expanded leaves or from the internode itself. Neither indoleacetic acid nor gibberellic acid stimulated renewed cambial activity when applied after the cessation of wood production. With both disbudded and intact shoots, the effectiveness of exogenous IAA declined with time, probably due to decreasing penetration through callus developing at the wounded surface. It is suggested that this apparent change in IAA effectiveness may explain some discrepancies between the results of previous observers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384186
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  • 3
    Electronic Resource
    Electronic Resource
    Tracheid length in relation to seedling height in conifers (1971)
    Springer
    Wood science and technology 5 (1971), S. 135-146 
    Details
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Changes in tracheid length during the development of primary and secondary xylem are analysed in relation to the division and elongation of cambial initials, in first year seedlings ofPinus sylvestris andPicea sitchensis. During primary and early secondary growth tracheid length varies with leaf internode length, but this relationship soon becomes obscured during later secondary growth. Correlations between seedling height and tracheid length thus depend on variation in tracheid length with radial xylem increment before and after terminal bud production. Since the relation between shoot and tracheid length is a complex one, the clonseness of the correlation varies with environmental treatment, but overall, a doubling of shoot length increased tracheid length by about 10%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01134224
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  • 4
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    Control of miniature proton exchange membrane fuel cells based on fuzzy logic (2004)
    Elsevier
    Details
    Publication Date: 2004-04-01
    Print ISSN: 0378-7753
    Electronic ISSN: 1873-2755
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Elsevier
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  • 5
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    Wood structure and production within the trunk and branches of Piceasitchensis in relation to canopy formation (1979)
    Canadian Science Publishing
    Details
    Publication Date: 1979-09-01
    Description: The seasonal progress of wood production and variation in tracheid dimensions were followed systematically along the trunk and main branches of Piceasitchensis trees and analysed in relation to the distribution of light intensity and leaf weight as the canopy develops. The aim was to provide data towards building models to predict effects of management on within-tree patterns of wood production and structure. Tracheid production began earliest at the tips of branches towards the base of the crown; the data show that tracheid production in the main stem began earliest several internodes below the leader, its onset progressing faster and having a shorter distance to travel down the upper branches. Tracheid production appeared to cease simultaneously throughout the trunk in codominant trees; it ceased earlier in severely suppressed trees, which consequently produced little or no latewood.In the main stem, maximum ring width occurred at least one internode above that carrying maximum total leaf dry weight. Maximum rate of tracheid production occurred one or two internodes above those having maximum current leaf dry weight, several internodes above the maximum total leaf weight. In branches, rate of wood production was closely correlated with light intensity.The seasonal increase in wall thickness from early- to latewood occurred more rapidly as you progress down the main stem to below the crown in 16-year-old trees; hence, Mork latewood began progressively earlier lower down the stem; this pattern was not developed in the trunk of younger trees. In all branches, latewood began earlier at the base than at the tip, owing to a more rapid seasonal increase in wall thickness towards the branch base. Tracheid diameter increased from the leader down to midcrown. In branches, partial correlations suggest that tracheid diameter varied with light intensity at the tip but inversely with whorl number at the branch base.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 6
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    Variation of fibre length within trees of Fraxinusexcelsior (1978)
    Canadian Science Publishing
    Details
    Publication Date: 1978-06-01
    Description: A systematic internodal analysis within three 22-year-old trees of European ash (Fraxinusexcelsior L.) showed that fibre length increased rapidly from the first ring from the pith outwards to about ring 7 (which coincided with maximum leaf weight within the crown), then increased more slowly to a maximum at about ring 14 (formed below the base of the crown). Since there was little variation in this pattern of increase in fibre length with height in the tree, an increment core taken at breast height should give an adequate indication of fibre length in the whole trunk in trees of this age. Fibre length varied significantly between seasons, independent of age or level in tree.Within growth rings, fibre length increased from earlywood to latewood, reaching a maximum before the end of the latewood. Fibre length was not correlated with ring width between rings (excluding the first five rings from the pith); this suggests that in Fraxinusexcelsior management treatments increasing wood production would not necessarily have an adverse effect on fibre length.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 7
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    Reactivation of vessel expansion in relation to budbreak in sycamore (Acerpseudoplatanus) trees (1987)
    Canadian Science Publishing
    Details
    Publication Date: 1987-10-01
    Description: The origin and progress of production of the first vessels of the new growth ring has been followed within trees of sycamore (Acerpseudoplatanus L.) and compared with stages of bud and shoot development within the crown and with variation in temperature at bud level. Reactivation of vessel expansion originated at the bud base when the bud had elongated 50% over dormant length; this stage of budbreak was delayed by 2 days for each metre up the crown. Vessel expansion did not appear to progress actively down branches until the leaf tips began to emerge. Changes in carbon partitioning may suggest that this lag period is associated with the importing phase of bud growth, progress beginning when the leaves become self-sufficient in assimilates. After the lag period, progress of vessel expansion down the branches was estimated to be about 3 cm day−1. Expanding vessels reached the trunk first in upper or middle crown, while the predetermined leaves of the lower and middle crown buds were expanding. Vessel expansion progressed more rapidly down the trunk than down branches; the predetermined leaves of the lower to middle crown had fully expanded by the time vessel expansion reached the base of the trunk.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 8
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    Some quantitative effects of indoleacetic acid on the wood production and tracheid dimensions of Picea (1977)
    Springer
    Details
    Publication Date: 1977-01-01
    Print ISSN: 0032-0935
    Electronic ISSN: 1432-2048
    Topics: Biology
    Published by Springer
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  • 9
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    Influence of Growth Rate and Cambial Age on Density of Rauli (Nothofagus nervosa) in Relation to Vessel Lumen Areas and Numbers (1999)
    De Gruyter
    Details
    Publication Date: 1999-03-01
    Description: Summary To assess the likely effects of silvicultural treatment on the wood quality of Nothofagus nervosa grown in the UK, and the possibilities of independent selection within seed origins for density and growth rate, ring width and wood density were analysed from pith to bark of 19 trees. Variations in vessel lumen size, vessel number mm−2, and total lumen area mm−2 were analysed in ten trees. Since density increased by only 0.005g cm−3 per mm increase in ring width, silvicultural practices such as initial spacing and thinning are not likely to have a substantial effect on the wood density of rauli. Similarly, variation in density with cambial age was significant but relatively minor in the 40- and 60-year old trees of the present sample, suggesting that the rotation length is unlikely to have any practical influence on the density of rauli. Considerable between-tree differences in density were found which did not correspond to differences in ring width, suggesting it should be feasible to select independently for density and growth rate. These differences in density were associated with differences in both vessel lumen size and vessel number mm−2
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
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  • 10
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    Tracheid Dimensions in Relation to Shoot Vigour in Picea (1973)
    Oxford University Press
    Details
    Publication Date: 1973-01-01
    Print ISSN: 0015-752X
    Electronic ISSN: 1464-3626
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Oxford University Press
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