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  • Springer  (38)
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  • Articles  (38)
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  • 1
    ISSN: 1572-879X
    Keywords: aluminum oxide ; hydroxyl groups ; rhodium ; growth ; scanning tunneling microscopy ; infrared spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In order to investigate how the presence of surface hydroxyl groups on oxide surfaces affects the interaction with the supported metal, we have modified a well-ordered alumina film on NiAl(110) by Al deposition and subsequent exposure to water. This procedure yields a hydroxylated alumina surface as revealed by infrared and high-resolution electron energy loss spectroscopy. By means of scanning tunneling microscopy, we have studied the growth of rhodium on the modified film at 300 K. Clear differences in the particle distribution and density are observed in comparison to the clean substrate. While, in the latter case, decoration of domain boundaries as typical defects of the oxide film governs the growth mode, a more isotropic island distribution and a drastically increased particle density is found on the hydroxylated surface. From infrared data, it can be deduced that the growth is connected with the consumption of the hydroxyl groups due to the interaction between the metal deposit and the hydroxylated areas. This finding is in line with photoemission results published earlier.
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  • 2
    Electronic Resource
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    Journal of chemical ecology 26 (2000), S. 2015-2023 
    ISSN: 1573-1561
    Keywords: Allelopathy ; growth ; phenolics ; Hebeloma ; Hymenoscyphus ; Picea abies ; Vaccinium myrtillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Allelopathy due to humus phenolics is a cause of natural regeneration deficiency in subalpine Norway spruce (Picea abies) forests. If inhibition of spruce germination and seedling growth due to allelochemicals is generally accepted, in contrast there is a lack of knowledge about phenolic effects on mycorrhizal fungi. Thus, this work tested effects of a humic solution and its naturally occurring phenolics on the growth and respiration of two mycorrhizal fungi: Hymenoscyphus ericae (symbiont of Vaccinium myrtillus, the main allelochemical-producing plant) and Hebeloma crustuliniforme (symbiont of P. abies, the target plant). Growth and respiration of H. crustuliniforme were inhibited by growth medium with the original humic solution (−6% and −30%), respectively, whereas the same humic solution did not affect growth but decreased respiration of H. ericae (−55%). When naturally occurring phenolics (same chemicals and concentrations in the original humic solution) were added to the growth medium, growth of H. crustuliniforme was not affected, whereas that of H. ericae significantly increased (+10%). We conclude that H. ericae is better adapted to the allelopathic constraints of this forest soil than H. crustuliniforme and that the dominance of V. myrtillus among understory species could be explained in this way.
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  • 3
    ISSN: 1573-1561
    Keywords: Nicotiana sylvestris ; nitrogen ; nicotine ; allocation ; growth ; reproduction ; induced defenses ; costs of defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We present the first evidence for a fitness cost of an inducible response that is detectable in a nitrogen (N) currency. Nicotine is an induced defense in Nicotiana sylvestris that can utilize 5–8% of the plant's total N, an investment that apparently cannot be recouped by metabolism. Induced nicotine production is endogenously regulated by jasmonic acid (JA), and we treated leaves with the methyl ester of this wound hormone (MeJA) in quantities (0, 25, 250 μg) known to elicit changes in endogenous JA and subsequent nicotine responses comparable to those elicited by mechanical wounding and herbivory in this species. We grew plants in competition chambers (CCs) in which three same-sized plants could compete for a communal but fixed pool of 15NO3 to quantify the outcome of competition for this fitness-limiting resource that is used both in defense and seed production. Competition profoundly increased all measures of growth and reproductive performance measured per milligram of N acquired. While plants acquired all the N supplied to them in the hydroponic solution, plants grown in CCs (as compared those grown in individual chambers—ICs) retained more of this N and produced more biomass, had larger nicotine contents, allocated less of their N to nicotine, produced larger floral stalks with more flowers, aborted fewer flowers, matured more capsules, and produced a greater mass of seed. Plants grown in ICs produced heavier seed, but this difference did not translate into a difference in seed viability. MeJA treatment increased nicotine concentrations in proportion to the amount applied and significantly reduced growth (13–23%) and reproductive (31–44%) performance for plants grown with uninduced competitors, reflecting a large opportunity cost of induction. The effects of MeJA treatment on growth and reproduction were significantly less pronounced for plants grown in ICs. MeJA treatment significantly reduced the ability of plants to compete for [15N]KNO3 (reducing uptake by 9.5% and 23.7% for 25- and 250-μg MeJA-treated plants, respectively); no reductions in N acquisition were found in IC grown plants treated with MeJA. This impairment of competitive ability could account for 41–47% of the jasmonate-induced reductions in biomass by the day 15 harvest and 12–20% of the reductions in seed set and, in addition, created by "opportunity benefit" for neighboring uninduced plants, which grew larger, aborted fewer flowers, and matured more seed (a 28% increase) than did uninduced plants competing with similarly uninduced plants. Competition dramatically increased plant growth and reproductive performance, and MeJA treatment of these high-performing plants significantly reduced their competitive ability, which translated into opportunity costs for induced plants and opportunity benefits for neighboring uninduced plants. Induced plants minimized these fitness costs by reducing their use of recently acquired N for nicotine biosynthesis when growing with competitors. MeJA treatments also altered stalk length, flower production, flower abortion, and allocation to seed mass. In spite of all this plasticity, induced responses incur large fitness costs, costs that could be in part attributed to reductions in competitive ability for N. We conclude that inducibility functions to minimize these costs.
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  • 4
    ISSN: 1573-4919
    Keywords: NADH oxidase ; protein disulfide-thiol interchange ; dipyridyl-dithio substrates ; plasma membrane ; auxin ; 2,4-dichlorophenoxyacetic acid ; growth ; plant (Glycine max)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Dipyridyl-dithio substrates were cleaved by isolated vesicles of plasma membranes prepared from etiolated hypocotyls of soybean. The cleavage was stimulated by auxins at physiological concentrations. The substrates utilized were principally 2,2′-dithiodippyrine (DTP) and 6,6′-dithiodinicotinic acid (DTNA). The DTP generated 2 moles of 2-pyridinethione whereas the 6,6′-dithiodinicotinic acid generated 2 moles of 6-nicotinylthionine. Both products absorbed at 340 nm. The auxin herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D) stimulated the activity approximately 2-fold to a maximum at about 10 μM. Concentrations of 2,4-D greater than 100 μM inhibited the activity. Indole-3-acetic acid stimulated the activity as well. The growth-inactive auxin, 2,3-dichlorophenoxyacetic acid (2,3-D), was without effect. DTNA cleavage correlated with oxidation of NADH and reduction of protein disulfide bonds reported earlier in terms of location at the external plasma membrane surface, absolute specific activity, pH dependence and auxin specificity. The dipyridyl-dithio substrates provide, for the first time, a direct measure of the disulfide-thiol interchange activity of the protein previously measured only indirectly as an auxin-dependent ability of isolated plasma membrane vesicles to restore activity to scrambled and inactive RNase.
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  • 5
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    Journal of chemical ecology 25 (1999), S. 1455-1479 
    ISSN: 1573-1561
    Keywords: Turnera ulmifolia ; Euptoieta hegesia ; cyanogenesis ; Anolis sagrei ; tritrophic interactions ; host range ; sequestration ; growth ; development ; oviposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We examine the effects of the cyanogenesis polymorphism in Turnera ulmifolia on larvae, pupae, and adults of Euptoieta hegesia, the most damaging herbivore of T. ulmifolia in terms of tissue loss per unit time. We provide evidence that female E. hegesia do not show preference for host plants on the basis of their cyanogenesis level but do prefer T. ulmifolia over equally cyanogenic, closely related secondary host-plant species (Passiflora sp.). Similarly, cyanogenesis in T. ulmifolia has little effect on the food preference, growth, or development of the larvae. The potential host range of E. hegesia is limited, even within the genus Turnera, but this does not appear to be due to host-plant cyanogenesis. Pupae suffer very high mortality levels in the wild that are not associated with host-plant cyanogenesis, although our studies indicate that larvae are capable of sequestering cyanogenic glycosides from their host plants and possibly of synthesizing these or similar compounds. We provide evidence that the presence of sequestered cyanogenic compounds in the larvae protects them from terrestrial-based predators such as Anolis lizards
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  • 6
    ISSN: 1573-1561
    Keywords: European corn borer ; Ostrinia nubilalis (Hübner) ; growth ; development ; fecundity ; oviposition ; behavior ; eggs ; DIMBOA ; water extract ; plant extract ; maize ; Peruvian maize ; maize accessions ; host plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Twelve Peruvian maize, Zea mays, accessions were selected because of their relatively high level of field resistance to first-generation European corn borer (ECB), Ostrinia nubilalis, larval leaf-feeding. Water extracts of freeze-dried, powdered, leaf tissue were incorporated into a standard ECB diet, fed to larvae, and the effects on larval growth, development, and fecundity were measured. Larval and pupal weights were monitored as were the time elapsed in the larval, pupal, and adult stages. Adult fecundity and egg fertility were recorded. The experiment was a randomized block design (larvae and pupae) or a completely randomized design (adults) and analyzed with ANOVA (α = 0.05). Pairwise comparisons were made between groups of insects grown on diets containing extracts from the Peruvian lines, a standard diet, or diets containing extracts of a known susceptible inbred, and a known resistant inbred line. Survival was analyzed with a chi-squared test (α = 0.05). Two Peruvian accessions significantly reduced female larval and pupal weights, extended pupal and adult development time, and decreased survival of pupae and adults. Water extracts also had a pronounced impact on males; two accessions significantly reduced pupal weight and extended the time required to pupate, and one reduced male survival to adults. The results indicate that water-soluble factors from resistant Peruvian accessions inhibit the growth, developmental time, and survival of ECB. These resistance factors could be useful in the development of maize germplasm with insect-resistant traits.
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  • 7
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    Interface science 7 (1999), S. 285-295 
    ISSN: 1573-2746
    Keywords: computer simulation ; growth ; energy dissipation ; grain boundaries ; triple nodes (Interfaces) ; triple line (Interfaces)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Vertex dynamics models in two and three dimensions are applied to study grain growth including a limited mobility of triple points (two dimensions) and triple lines (three dimensions). A recent experiment on a triple node is used to validate the proposed model. The reduced triple node/line mobility in the case of a polycrystalline sample is shown to influence both, the grain growth kinetics and the grain size distribution function.
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  • 8
    ISSN: 1573-2746
    Keywords: polycrystal ; ionic ; oxide ; molecular-dynamics ; simulation ; growth ; thin film ; structure ; characterization ; grain boundary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A simulation methodology for the synthesis of polycrystalline, ionic thin films is developed. The method involves the preparation of a polycrystalline substrate onto which a thin film is subsequently grown by crystallization from the melt. A detailed structural analysis of a textured sixteen-grain FeO film, with a grain size of approximately 4.7 nm, shows that the interiors of the grains are almost perfect single crystals with only a very few vacancies and no interstitials. The grains are delineated by 〈001〉 tilt grain boundaries; as expected, the low-angle grain boundaries in the film consist of arrays of dislocations, while the high-angle grain boundaries are relatively narrow and well ordered.
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  • 9
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    Journal of thermal analysis and calorimetry 52 (1998), S. 537-542 
    ISSN: 1572-8943
    Keywords: fractals ; growth ; nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The author presents a model based on multi-step nucleation for the heterogeneous decompositions described by nucleation and growth phenomena, taking into account the fractal nature of the nuclei.
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  • 10
    ISSN: 1573-4919
    Keywords: annexin V ; cardiac myocyte ; growth ; hypertrophy ; heart
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Recently it was shown that annexin V is the most prominent member of the annexin family in the adult heart [1]. Amongst others, annexin V has been suggested to play a role in developmental processes. The aim of the present study was to explore whether in the heart annexin V content and localization change during maturational and hypertrophic growth, in order to obtain indications that annexin V is involved in cardiac growth processes. First, in the intact rat heart annexin V content and localization were studied during perinatal development. It was clearly demonstrated that annexin V content in total heart transiently increased in the first week after birth, from 0.79 ± 0.06 µg/mg protein at l day before birth to a peak value of 1.24 ± 0.08 µg/mg protein 6 days after birth, whereafter annexin V protein levels declined to a value of 0.70 ± 0.06 µg/mg protein at 84 days after birth (p 〈 0.05). Differences in annexin V content were also observed between myocytes isolated from neonatal and adult hearts [0.81 ± 0.09 and 0.17 ± 0.08 µg/mg protein, respectively (p 〈 0.05)]. Moreover, during cardiac maturational growth the subcellular localization of annexin V might change from a cytoplasmic to a more prominent sarcolemmal localization. Second, in vivo hypertrophy induced by aortic coarctation resulted in a marked degree of hypertrophy (22% increase in ventricular weight), but was not associated with a change in annexin V localization or content. The quantitative results obtained with intact hypertrophic rat hearts are supported by findings in neonatal ventricular myocytes, in which hypertrophy was induced by phenylephrine (10-5 M). In the latter model no changes in annexin V content could be observed either. In conclusion, the marked alterations in annexin V content during the maturational growth in the heart suggest a possible involvement of this protein in this process. In contrast, the absence of changes in annexin V content and localization in hypertrophied hearts compared to age matched control hearts suggests that annexin V does not play a crucial role in the maintenance of the hypertrophic phenotype of the cardiac muscle cell. This notion is supported by observations in phenylephrine-induced hypertrophied neonatal cardiomyocytes.
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  • 11
    ISSN: 1573-4919
    Keywords: NADH oxidase ; plasma membranes ; growth ; retinol ; retinoids ; HeLa cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Several retinoids, both natural and synthetic, were evaluated for their ability to modulate NADH oxidase activity of plasma membranes of cultured HeLa cells and the growth of HeLa cells in culture. Both NADH oxidase activity and the growth of cells were inhibited by the naturally-occurring retinoids all trans-retinoic acid (tretinoin) and retinol as well as by the synthetic retinoids, trans-acitretin, 13-cis-acitretin, etretinate and arotonoid ethylester (Ro 13-6298). For all retinoids tested, inhibition of NADH oxidase activity and inhibition of growth were correlated closely. With tretinoin, etretinate and arotonoid ethylester, NADH oxidase activity and cell growth were inhibited in parallel in proportion to the logarithm of retinoid concentration over the range of concentrations 10-8 to 10-5 M. Approximately 70% inhibition of both NADH oxidase activity and growth was reached at 10 µM. With retinol, trans-acitretin and 13-cis-acitretin, inhibition of NADH oxidase activity and growth also were correlated but maximum inhibition of both was about 40% at 10 µM. The possibility is suggested that inhibition of the plasma membrane NADH oxidase activity by retinoids may be related to their mechanism of inhibition of growth of HeLa cells in culture. (Mol Cell Biochem 166: 101-109, 1997)
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  • 12
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    Pharmaceutical research 14 (1997), S. 1122-1126 
    ISSN: 1573-904X
    Keywords: dissolution ; model ; growth ; fraction absorbed ; in vitro-in vivocorrelations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop a new approach for describing drug dissolution which does not require the presuppositions of time continuity and Fick's law of diffusion and which can be applied to both homogeneous and heterogeneous media. Methods. The mass dissolved is considered to be a function of a discrete time index specifying successive 'generations' (n). The recurrence equation: Φ n+1 = Φ n + r(l − Φn)(1 − Φn X 0/θ) was derived for the fractions of dose dissolved Φ n and Φn +1, between generations n and n + 1, where r is a dimensionless proportionality constant, X 0 is the dose and θ is the amount of drug corresponding to the drug's solubility in the dissolution medium. Results. The equation has two steady state solutions, Φ ss = 1 when (X 0/θ) ≤ 1 and Φ ss = θ/X 0 when (X 0/θ) 〉 1 and the usual behavior encountered in dissolution studies, i.e, a monotonic exponential increase of Φ n reaching asymptotically the steady state when either r 〈 θ/X 0 〈 1 or r 〈 1 〈 θ/X 0. Good fits were obtained when the model equation was applied to danazol data after appropriate transformation of the time scale to 'generations'. The dissolution process is controlled by the two dimensionless parameters θ/X 0 and r, which were found to be analogous to the fundamental parameters dose anddissolution number, respectively. The model was also used for the prediction of fraction of dose absorbed for highly permeable drugs. Conclusions. The model does not rely on diffusion principles and therefore it can be applied under both homogeneous and non-homogeneous conditions. This feature will facilitate the correlation of in vitro dissolution data obtained under homogeneous conditions and in vivo observations adhering to the heterogeneous milieu of the GI tract.
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  • 13
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    Journal of chemical ecology 23 (1997), S. 543-551 
    ISSN: 1573-1561
    Keywords: Temperature ; photoperiod ; hydroxamic acids ; growth ; defense ; secondary metabolites ; wheat ; Gramineae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of temperature and photoperiod on accumulation of hydroxamic acids (Hx) in wheat (Triticum aestivum L.) seedlings were evaluated under laboratory conditions. Hx concentrations were significantly higher at higher temperatures. No such clear trend was found for the photoperiod effect. The significant effect of temperature and photoperiod on growth rate of seedlings and the significant positive correlation between growth rate prior to analysis and levels of Hx, suggested that environmental effects on Hx accumulation were at least partially mediated through their effect on plant growth rate. After uncoupling the effect of environmental conditions from the effect of plant growth rate by statistical means the effect of temperature on Hx was no longer significant. Therefore, temperature effect was fully mediated by plant growth rate. Implications of the patterns found are discussed in issues of plant-defense general theories.
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  • 14
    ISSN: 1573-4919
    Keywords: heart ; postnatal development ; sarcoplasmic reticulum ; phospholamban ; calcium transport ; spontaneously hypertensive rats ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This comparative study investigates the relationship between sarcoplasmic reticulum (SR) calcium(Ca2+)-ATPase transport activity and phospholamban (PLB) phosphorylation in whole cardiac homogenates of spo`ntaneously hypertensive rats (SHR) and their parent, normotensive Wistar Kyoto (WKY) strain during early postnatal development at days 1, 3, 6, 12 and at day 40 to ascertain any difference in SR Ca2+ handling before the onset of hypertension. At day 1, the rate of homogenate oxalate-supported Ca2+ uptake was significantly higher in SHR than in WKY (0.25 ± 0.02 vs 0.12 ± 0.01 nmoles Ca2+/mg wet ventricular weight/min, respectively; p 〈 0.001). This interstrain difference disappeared with further developmental increase in SR Ca2+ transport. Western Blot analysis and a semiquantitative ELISA did not reveal any difference in the amount of immunoreactive PLB (per mg of total tissue protein) between strains at any of the ages studied. In addition, levels of phosphorylated PLB formed in vitro in the presence of radiolabelled ATP and catalytic (C) subunit of protein kinase A did not differ between SHR and WKY at days 1, 3, 6 and 12. At day 40, C subunit-catalyzed formation of 32P-PLB was reduced by 66% (p 〈 0.001) in SHR when compared to age-matched WKY In the early postnatal period between day 1 and 12 SR Ca2+-transport values were linearly related to the respective 32P-PLB levels of both SHR and WKY rats. The results indicate that cardiac SR of SHR can sequester Ca2+ at a much higher rate immediately after birth compared to WKY rats. The disappearance of this interstrain difference with further development suggests that some endogenous neuroendocrine or nutritional factor(s) from the hypertensive mother may exert an influence upon the developing heart in utero resulting in a transiently advanced maturation of the SR Ca2+ transport function in SHR pups at the time of birth.
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  • 15
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    Colloid & polymer science 274 (1996), S. 209-217 
    ISSN: 1435-1536
    Keywords: Crystallization ; nucleation ; growth ; non-isothermal crystallization ; thermal nucleation ; athermal nucleation ; transient effects ; relaxation times
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new model of crystallization kinetics in variable external conditions has been developed. The model concerns situations when temperature, pressure, stress, change in time. Compared to earlier models, the present treatment includes transient and athermal effects, proportional to the rate of change of the external conditions. The model can be used for simulation of crystallization in industrial processes (injection molding, fiber spinning, film blowing). The present paper offers general theoretical fundamentals of the model. Applications concerning more specific cases will be published separately.
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  • 16
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    Journal of chemical ecology 22 (1996), S. 709-717 
    ISSN: 1573-1561
    Keywords: Vole ; Microtus oeconomus ; birch ; Betula pendula ; dietary protein ; food consumption ; growth ; mortality ; liver glycogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of protein and birch bark powder (BBP) content of forage on food consumption and growth of root voles (Microtus oeconomus) was studied by feeding young voles with eight different diets for two weeks. Voles ate more when the protein content of forage was moderate (6%) or low (3%), and when BBP was added to the diets, as compared to a high (12%) protein diet without BBP addition. On high and moderate protein diets voles gained weight, whereas on low protein diets they lost weight. Addition of BBP caused reduced growth or weight loss. Consuming a diet with moderate (6%) protein and high BBP (20%) resulted in high mortality (9 of 10 died). These results show that root voles need at least 6% protein for growth and that the effect of birch bark depends on the protein content of the forage.
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  • 17
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    Colloid & polymer science 274 (1996), S. 197-208 
    ISSN: 1435-1536
    Keywords: Shear-induced crystallization ; nucleation ; growth ; overall kinetics ; polymer ; polypropylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The crystallization kinetics of polypropylene was observed during shear and after shear experiments under isothermal condition. The crystallizations were performed in a plate-plate and a fiber pull-out device. The nucleation density, the crystalline growth and the overall kinetics were measured and compared with data obtained in a similar way but during static experiments. The morphologies are spherulitic and formed from nuclei which seem to be randomly distributed. α-phase spherulites are always observed but with a nucleation density and a growth rate which depend on shearrate. The nucleation density is strongly enhanced by shear and acts as the main factor on the overall kinetics. The overall kinetics can be analyzed with a two-step Avrami model, where an Avrami exponentn 1 with a very high value is always observed first after shear and a more usual parametern 2 for the subsequent crystallization period. This high value ofn 1 seems to be related to the strong enhancement of nucleation density. The growth rate increases with the shear-rate, but the basic growth mechanisms do not seem to be modified. For crystallizations after shear the growth rate decreases with a long-time delay after shear but not down to the static value. The effect is characteristic of a partial relaxation of chain orientation after shear but with a very unusual time constant.
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  • 18
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    Molecular and cellular biochemistry 146 (1995), S. 63-69 
    ISSN: 1573-4919
    Keywords: rice bran oil ; growth ; plasma lipids ; fatty acids ; lipoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effects of feeding two levels of rice bran oil (RBO) on the growth, lipid parameters, and fatty acid composition of the plasma and liver of rats (Wistar strain) were compared with those produced on animals which had been fed the same levels of peanut oil (PNO). The control animals were fed synthetic diets containing 5 and 20% peanut oil (PNO) and the experimental groups were fed similar diets, containing the same level of rice bran oil (RBO). There was no significant difference with respect to the organ weights between the control and the experimental groups. In general, groups fed 20% oil gained more weight than groups fed 5% oil. The animals which received rice bran oil in their diet had, in general, comparatively lower levels of cholesterol, triglycerides and phospholipids. On the other hand, animals receiving 20% rice bran oil in their diet, showed an increase of 20% in high density lipoproteins (HDL-C), within 18 weeks (p〈0.05), when compared to the animals fed with peanut oil. Similarly, low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein cholesterol (VLDL-C) were lower in RBO-fed groups, than in the PNO-fed groups. There was, however, no significant differences in the cholesterol/phospholipid (C/P) ratio of the two groups. Analysis of plasma and of liver fatty acids indicated, in a general way, the type of fat consumed. There were no significant difference in the P/S ratio, nor any in the oleic/linoleic, oleic/stearic, palmitoleic/palmitic, oleic/palmitic, and oleic/palmitoleic ratios. Furthermore, levels of saturated (SAFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identical in both the groups. Thus, our results suggest that feeding a high level of rice bran oil (RBO) has no deleterious effect on the growth and blood lipid profile of rats.
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  • 19
    ISSN: 1432-1424
    Keywords: Water channels ; Vasopressin ; Rat kidney ; Immunocytochemistry ; Microtubules ; Cell polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Aquaporin 2 is a collecting duct water channel that is located in apical vesicles and in the apical plasma membrane of collecting duct principal cells. It shares 42% identity with the proximal tubule/thin descending limb water channel, CHIP28. The present study was aimed at addressing three questions concerning the location and behavior of the AQP2 protein under different conditions. First, does the AQP2 channel relocate to the apical membrane after vasopressin treatment? Our results show that AQP2 is diffusely distributed in cytoplasmic vesicles in collecting duct principal cells of homozygous Brattleboro rats that lack vasopressin. In rats injected with exogenous vasopressin, however, AQP2 became concentrated in the apical plasma membrane of principal cells, as determined by immunofluorescence and immunogold electron microscopy. This behavior is consistent with the idea that AQP2 is the vasopressin-sensitive water channel. Second, is the cellular location of AQP2 modified by microtubule disruption? In normal rats, AQP2 has a mainly apical and subapical location in principal cells, but in colchicine-treated rats, it is distributed on vesicles that are scattered throughout the entire cytoplasm. This is consistent with the dependence on microtubules of apical protein targeting in many cell types, and explains the inhibitory effect of microtubule disruption on the hydroosmotic response to vasopressin in sensitive epithelia, including the collecting duct. Third, is AQP2 present in neonatal rat kidneys? We show that AQP2 is abundant in principal cells from neonatal rats at all days after birth. The detection of AQP2 in early neonatal kidneys indicates that a lack of this protein is not responsible for the relatively weak urinary concentrating response to vasopressin seen in neonatal rats.
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  • 20
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    Journal of sol gel science and technology 2 (1994), S. 97-101 
    ISSN: 1573-4846
    Keywords: hybrid materials ; monodispersed particles ; growth ; seeds ; LCD spacer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper describes the attempt to prepare a new group of monodispersed silica-polymer hybrid particles, which consists of silica and amide polymer: poly(vinylpyrrolidone) (PVP) and poly(2-ethyloxazoline) (POXZ). Preparation method is based on the growth of hybrid seeds by the addition of TEOS-polymer solution. Monodispersed PVP-silica hybrid particles of 1.24 µm in diameter were prepared by growing the hybrid seeds of 0.54 µm by the addition of TEOS-PVP solution with ammonia catalyst. In the case of POXZ-silica particles, addition of TEOS-POXZ solution to the solution containing 0.54 µm seeds resulted in monodispersed POXZ-silica hybrid particles and four times repetition of the addition for particle growth gave the hybrid particles of the diameter of 1.6 µm. Improvement of mechanical properties of hybrid particles was observed when the particles were heated at 100 ∼ 200°C.
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    Journal of sol gel science and technology 2 (1994), S. 273-276 
    ISSN: 1573-4846
    Keywords: aging in silica gels ; growth ; aggregation ; X-ray scattering
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Growth and aging of silica aggregates are influenced both by temperature and by catalyzing fluorine ions as shown by SAXS and BET. It was found that both fluorine and increased temperature slightly increased the fractal dimension Df during aging, but the fluorine catalyzed system showed a lower BET surface area. To understand the effect of fluorine and increased temperature on the aggregates, 2D aggregations and SAXS simulations were carried out using two new programs GRASP and DALAI. In agreement with experiments it was found that binary RLCCA aggregates have a slightly higher Df value compared to DLCCA aggregates and that branch-flexibility during aging increases Df even further.
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  • 22
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    Journal of bioenergetics and biomembranes 26 (1994), S. 137-142 
    ISSN: 1573-6881
    Keywords: Adriamycin ; ascorbate ; electron transport ; growth ; plasma membrane (HL-60 cells)
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    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Adriamycin, 10−8–10−5 M, inhibited transplasma membrane electron transport of uninduced HL-60 cells susceptible to adriamycin and not in uninduced HL-60 cells resistant to adriamycin as measured by reduction of external ascorbate free radical. Electron flow across the plasma membrane was measured with the intact living cells by means of a simple assay procedure whereby the transported electrons were captured by ascorbate free radical to slow the rate of chemical oxidation of ascorbate. The response to adriamycin was rapid with maximum inhibition in less than 1 min. Preincubation was not required and the inhibition presumably was not mediated through effects on DNA replication or transcription. Except at the highest concentration tested of 10 µM, both transplasma membrane electron transport and growth were unaffected by adriamycin with a line of HeLa cells resistant to the drug. The findings provide evidence, using a physiological acceptor, ascorbate free radical, for a direct inhibition of transmembrane electron transport of HL-60 cells by adriamycin that correlates closely with adriamycin inhibition of cell growth. The lack of response with resistant cells suggests an alternative mechanism for adriamycin resistance not necessarily based on transport control.
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    Journal of bioenergetics and biomembranes 26 (1994), S. 421-433 
    ISSN: 1573-6881
    Keywords: NADH oxidase ; plasma membrane ; growth factors ; growth ; thiol/disulfide interchange ; membranes ; brefeldin A ; Golgi apparatus
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    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract An NADH oxidase activity of animal and plant plasma membrane is described that is stimulated by hormones and growth factors. In plasma membranes of cancer cells and tissues, the activity appears to be constitutively activated and no longer hormone responsive. With drugs that inhibit the activity, cells are unable to grow although growth inhibition may be more related to a failure of the cells to enlarge than to a direct inhibition of mitosis. The hormone-stimulated activity in plasma membranes of plants and the constitutively activated NADH oxidase in tumor cell plasma membranes is inhibited by thiol reagents whereas the basal activity is not. These findings point to a thiol involvement in the action of the activated form of the oxidase. NADH oxidase oxidation by Golgi apparatus of rat liver is inhibited by brefeldin A plus GDP. Brefeldin A is a macrolide antibiotic inhibitor of membrane trafficking. A model is presented where the NADH oxidase functions as a thiol-disulfide oxidoreductase activity involved in the formation and breakage of disulfide bonds. The thiol-disulfide interchange is postulated as being associated with physical membrane displacement as encountered in cell enlargement or in vesicle budding. The model, although speculative, does provide a basis for further experimentation to probe a potential function for this enzyme system which, under certain conditions, exhibits a hormone- and growth factor-stimulated oxidation of NADH.
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  • 24
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    Journal of chemical ecology 19 (1993), S. 893-906 
    ISSN: 1573-1561
    Keywords: Acacia cyclops ; allelopathy ; competition ; inhibition ; growth ; leachate ; nutrients ; phytotoxicity ; stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Aqueous leachates derived from canopy phyllodes of invasiveAcacia cyclops affected growth of a range of shrub species independently of nutrient input effects. All plants showed a sublethal phytotoxic response. Root mass was generally less adversely affected than shoot mass and, while decreasing significantly in response to the 10% concentration, showed no such response to the 1% solution. Root-shoot biomass ratios increased, except inEuphorbia burmannii, which may recognize intrinsic root architecture limitations on extensive exploitation of toxin-free soil. Application of surface plant litter from underA. cyclops canopies stimulated the production of basal stems inProtasparagus capensis andEriocephalus racemosus but was insufficient to significantly reduce root-shoot ratios. Plant growth inhibition was maximized by canopy leachate compounded by surface litter effects inAnthospermum spathulatum. The net effect of leachate at high concentration on biomass allocation in certain shrub species may help explain their patterns of association and disassociation withA. cyclops.
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    BioMetals 5 (1992), S. 149-156 
    ISSN: 1572-8773
    Keywords: Hg2+ toxicity ; cyanobacterium ; Nostoc calcicola ; growth ; photopigments ; nucleic acids ; photosynthesis ; membrane integrity ; nutrient uptake ; enzymes
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Toxicological responses of the filamentous N2-fixing cyanobacteriumNostoc calcicola Bréb. towards Hg2+ were studied to enumerate the decisive lethal events. In low-dose, long-term experiments (0.05–0.25 μm Hg2+, 10 days), photoautotrophic growth was severely inhibited with concurrent loss of photosynthetic pigments (phycocyanin〉chlorophyll α〉carotenoids) and nucleic acids. The termination of growth after a day 4 exposure to 0.25 μm Hg2+ has been attributed to the complete inhibition ofin vivo photosynthetic activity in the cyanobacterium (O2 evolution〉14CO2 incorporation). The elevated Hg2+ concentrations irreversibly damaged the cell membrance as observed under light microscopy, and as indicated by the leakage of intracellular electrolytes and phycocyanin. In high-dose, short-term experiments (0.5–20.0 μm Hg2+, up to 6 h), thein vivo activities of selected enzymes (glutamine synthetase 〉 nitrate reductase 〉 nitrogenase) were less inhibited by Hg2+ than the uptake of nutrient ions (NH 4 + 〉NO 3 − 〉PO 4 3− ).
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  • 26
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    Journal of chemical ecology 18 (1992), S. 39-51 
    ISSN: 1573-1561
    Keywords: Artemisia princeps var.orientalis ; allelopathy ; water extract ; concentration ; germination ; growth ; juvenile leaf extract
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The allelopathic effects of wormwood plants (Artemisia princeps var.orientalis) and their possible phytotoxicity on receptor species were investigated. The aqueous extracts of mature leaf, stem, and root of wormwood plants caused significant inhibition in germination and decreased seedling elongation of receptor plants, whereas germination of some species was not inhibited by extracts of stems and roots. Dry weight growth was slightly increased at lower concentrations of the extract, whereas it was proportionally inhibited at higher concentrations. The calorie value of the organic matter in receptor plants measured by bomb calorimeter was reduced proportionally to the extract concentration. However, results with extracts of juvenile leaf did not correlate with inhibition or promotion of elongation and dry weight.
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  • 27
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    Journal of chemical ecology 18 (1992), S. 1981-1990 
    ISSN: 1573-1561
    Keywords: Allelopathy ; ferulic acid ; amylase ; maltase ; invertase ; acid protease ; acid phosphatase ; Zea mays ; growth ; root ; shoot
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Ferulic acid was tested for its effect on the growth of root and shoot, fresh and dry weights, and hydrolytic enzyme activities of germinating maize seeds. The results showed that root growth was inhibited more than shoot growth. A significant reduction in the activities of hydrolytic enzymes was also observed, which reflects a mechanism of action for the natural growth inhibitors, which may include other phenolic compounds.
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    Plasma chemistry and plasma processing 11 (1991), S. 371-386 
    ISSN: 1572-8986
    Keywords: Plasmas ; aerosol ; modelling ; growth ; reactor
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model is proposed for the analysis of the production of ultrafine particles in thermal plasma reactors. The model initially solves the fluid flow, temperature, and concentration fields using a classical control volume approach. The nucleation and growth of ultra fine particles are then solved along each streamline. The evolution of the particle distribution is described by a statistical approach, using the first moments of the distribution as the dependent variables. Brownian coalescence is considered in the free molecular regime. In the discussion, the model is used to demonstrate the effects of some important parameters, such as the initial concentration of metal vapor, its radial distribution, and the radial injection of a cooling gas, on the particle size distribution.
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    Colloid & polymer science 269 (1991), S. 695-703 
    ISSN: 1435-1536
    Keywords: 2D spherulire ; growth ; linear temperature field ; calculus of variations ; theory and experiments
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A 2D spherulite grows in a linear-temperature field from a nucleus of polypropylene at (0,0). The growth lines and the growth fronts are computed by the calculus of variations. The agreement between theory and experiment is satisfactory
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    Colloid & polymer science 269 (1991), S. 689-694 
    ISSN: 1435-1536
    Keywords: 2D spherulite ; growth ; field of growth rate ; calculus of variations ; linear growth rate
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We propose to take the calculus of variations in order to compute the shape of a growing 2D spherulite in an uniaxial field of growth rate. We are concerned with the growth line (a path that is traveled in the shortest possible time from nucleus to a point (x1, y1), where a molecule just crystallizes) and the growth front (the times between spherulite and supercooled material). The Euler differential equation—a result of the calculus of variations—is derived for all uniaxial growth ratesv (x). Here we especially investigatev(x)=px+q.
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  • 31
    ISSN: 1573-1561
    Keywords: European corn borer ; Ostrinia nubilalis ; Lepidoptera ; Pyralidae ; corn ; DIMBOA ; 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one ; tritiated DIMBOA ; toxicokinetics ; topical application ; body burden ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), the major hydroxamic acid present in corn, and its tritiated derivative, were prepared synthetically for use in the determination of the toxicokinetics of this insect deterrent in the European corn borer (ECB),Ostrinia nubilalis. In growth studies with DIMBOA (0, 0.05, 0.2, and 0.5 mg/g diet), the mean time to pupation and adult emergence were significantly lengthened by an increase in concentration. Pupal and adult weights, for both female and male, decreased with an increase in concentration. Increased larval and pupal mortality occurred at the highest concentration of DIMBOA. DIMBOA, at concentrations of 0.2 and 0.5 mg/g diet, resulted in a decrease in the number of egg masses produced per female, and at 0.5 mg/g diet, in a decrease in the number of eggs per egg mass. Larvae fed from the neonate stage on a diet containing 0.2 mg [3H]- + [1H]DIMBOA/g diet showed an increase in the content of label from fourth to fifth instar, but levels declined at pupation and emergence. A large amount of the labeled compounds was excreted by the insect in the pupal case. In dose-related studies, both uptake and excretion increased with an increase in concentration of DIMBOA (0.05, 0.2, 0.4 mg/g diet), while a body burden (concentration in the tissues/concentration in the frass) of approximately 0.25 was maintained for all concentrations. At the highest dose of DIMBOA (0.4 mg/g), the ECB increased consumption, possibly to compensate for the toxic effects of the compound. In topical application studies, elimination of the labeled compound in the frass was rapid, reaching 65% by 4 hr and 88% by 48 hr. Accumulation of label in tissues other than hemolymph was low. The results show that the ECB does possess adaptive mechanisms to deal with the effects of this host-derived compound.
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    Journal of chemical ecology 13 (1987), S. 39-46 
    ISSN: 1573-1561
    Keywords: Solanum ; glycoalkaloid ; Leptinotarsa decemlineata ; protein ; growth ; Coleoptera ; Chrysomelidae ; α-tomatine ; α-solamarine ; β-solamarine ; α-solamine ; α-chacomine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Growth of larvae of the Colorado potato beetle,Leptinotarsa decemlineata (Say), as measured by weight gain, was determined when larvae were reared on synthetic diets containing measured quantities of protein and one of fiveSolanum glycoalkaloids. Data were analyzed to determine if growth was affected by these two aspects of phytochemical variation independently, or if there was a significant interaction component in larval weight gain to simultaneous variation in protein and glycoalkaloid concentration. For four of the five glycoalkaloids examined, a bivariate regression model without interaction accurately accounted for growth ofL. decemlineata larvae. For alpha-tomatine, however, a regression model with the addition of a (protein × glycoalkaloid) interaction term more accurately accounted for larval growth. The influence of this interaction was less than either protein or glycoalkaloid concentration alone. The variation in protein concentration accounted for most of the variation in larval growth, and high protein concentrations could more than offset the effect of high concentration of any of the five glycoalkaloids.
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  • 33
    ISSN: 1573-4935
    Keywords: muscle ; growth ; adrenergic agents ; clenbuterol ; propranolol
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of propranolol on clenbuterol-induced changes in muscle fibre size and protein content were studied. Propranolol did not inhibit the ability of clenbuterol to stimulate protein accretion but reduced the increase in muscle fibre size. The compositional and physical characteristics of clenbuterol-induced muscle growth thus appeared to be separated by propranolol.
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    Journal of chemical ecology 12 (1986), S. 713-728 
    ISSN: 1573-1561
    Keywords: Alkaloids ; phenolics ; feeding trials ; digestibility ; growth ; Lespedeza cuneata ; Penstemon digitalis ; Microtus pennsylvanicus ; Microtus ochrogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Lespedeza cuneata contains high levels of phenolics and is a common food plant of the meadow vole (Microtus pennsylvanicus);Penstemon digitalis contains substantial quantities of alkaloids and is a common food plant of meadow voles and prairie voles (M. ochrogaster). We investigated the palatability of these plants and the effects of their secondary compounds on the digestion efficiencies and growth of both species of voles. Voles ate very little of either plant when alternative food was present. Phenolics and alkaloids were extracted from the plants, incorporated into separate artificial diets, and fed to weanling voles for three weeks.Lespedeza phenolics reduced the growth of meadow voles but not prairie voles throughout the feeding trial. These compounds disrupted digestion, reducing protein digestibility by more than half.Penstemon alkaloids lowered only the initial growth rates of prairie voles and had no significant effect on meadow voles. Prairie voles tended to increase food consumption rates on bothLespedeza andPenstemon diets. This response offset some of the decrease in digested protein intake in the first case, and offset the increased metabolic cost of processing the diet in the latter case. Our results indicate that althoughLespedeza phenolics andPenstemon alkaloids do influence consumption and digestibility of artificial diets, they do not greatly reduce the performance (i.e., growth or survival) of voles when consumed at levels generally observed for wild voles. However, these compounds probably do place an upper limit on the amount of freshLespedeza andPenstemon that can be consumed and contribute to the generalist feeding strategy of voles.
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    Journal of chemical ecology 11 (1985), S. 1427-1438 
    ISSN: 1573-1561
    Keywords: Salmon ; Salmo salar ; olfaction ; anosmia ; pheromones ; smolt transformation ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of olfactory deprivation on the process of smolt transformation in Atlantic salmon (Salmo salar L.) was investigated. Salmon parr were rendered anosmic by heat-cauterizing in November, and, together with controls, size, purine deposition (silvering), and mortality were monitored throughout spring in individuals within sibling groups. In May the fish were exposed to seawater (3.2% salinity) to determine levels of smoking in anosmic fish compared with control fish. Olfactory deprivation was found to induce a negative effect on survival in both anosmic fish as well as controls when reared within the same rearing tank. A 54% survival was metered in anosmic fish as opposed to only 26% survival in control fish during the experimental period. The low survival rates observed are suggested to result from abnormal behavior in anosmic fish due to lack of proper olfactory stimuli. Within each strain, the anosmic fish were found shorter and displayed less-silvering than their control fish at the end of the experimental period. Further, since control fish could withstand salinity exposure longer than anosmic fish, smolting is suggested to have been retarded among the anosmic fish. Olfactory influence on smolt transformation may be caused by conspecific pheromones secreted for the purpose of mediating effects of life-history patterns in salmonid fishes.
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    Journal of pharmacokinetics and pharmacodynamics 10 (1982), S. 335-348 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; bioavailability ; growth ; literature growth ; logistic function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The literature growth in pharmacokinetics and bioavailability between the years 1964 and 1980 is analyzed. During much of this period, the literature doubled approximately every 1.6 years. However, during the period 1978–1980, little or no growth was observed. During the period 1950–1967, the total chemical literature increased exponentially with a half-life of 8.28 years; between 1968 and 1980, the half-life was 12.4 years. Thus, the pharmacokinetic literature increased at a much more rapid pace than did the total chemical literature in general. The subject of growth is considered in a general context, particularly as influenced by psychological, sociological, political, and economic factors. It is concluded that while mathematical functions may adequately describe past literature trends, they have little if any utility in predicting future trends in specific research areas such as pharmacokinetics.
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  • 37
    ISSN: 1573-4927
    Keywords: rat liver ; chromatin ; proteins ; growth ; heterosis
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Electrophoretic comparisons of histones and other acid-extractable chromatin proteins isolated from the livers of growing F344 inbred rats and a heterotic paternal hybrid derived by crossing F344 males with Holtzman females reveal significant heterogeneity among a class of nonhistone components soluble in acid. These variations appear to be age and line specific and show more variation in the inbred than the hybrid. Comparisons of the acid-insoluble nonhistone proteins by sodium dodecylsulfate gel electrophoresis reveal significant quantitative changes in a 28,600 dalton polypeptide present in large quantities at 30, 35, and 50 days of age in the hybrid and at 40 and 45 days only in the inbred. Other minor variations were noted in a class of proteins of 40,000–45,000 molecular weight and in those of very high molecular weight (100,000–200,000). Such variations could be a reflection of or prelude to changes in genetic activity and could ultimately be important in the control of growth patterns of developing heterotic animals.
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    Biochemical genetics 14 (1976), S. 281-292 
    ISSN: 1573-4927
    Keywords: rat liver ; chromatin ; growth ; heterosis ; RNA ; DNA ; protein
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The manifestation of hybrid vigor with regard to the inheritance of body weight was established as a postweaning phenomenon in rats. Liver weight gain generally corresponded to body weight gain and also reflected hybrid vigor. The protein/DNA ratios of the chromatin from livers of inbred and heterotic hybrid male rats were found to increase with increasing age in growing rats. Hybrid chromatin had higher protein/DNA ratios throughout the age range studies. The difference between hybrids and inbreds were greatest in the early postweaning stages of growth and maturation. The RNA/DNA ratios of chromatin from livers of inbred and hybrid male rats were also found to exhibit trends within certain developmental periods.
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