ZIB

1

Digitale Medien

Sustained ingestion of methadone and the sleep of monkeys (1978)

Snyder, E. W. ; Dustman, R. E. ; Beck, E. C.

Springer

Psychopharmacology 60 (1978), S. 29-34

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ISSN: 1432-2072

Schlagwort(e): Sleep ; Methadone ; Sustained ingestion ; Monkey

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Methadone HCl was administered daily to four stump-tailed macaques. The animals' sleep was periodically examined throughout a year of methadone maintenance and, in two animals, during eight months of withdrawal. REM sleep was substantially decreased by methadone treatment and gradually returned to predrug values over a 6-to 8-month period of maintenance. Measures of non-REM sleep and awakenings showed similar disruption with no return to predrug values. These changes were not correlated with alterations in plasma-methadone concentrations. REM sleep rebound occurred temporarily upon drug with-drawal in two animals, but no consistent sleep disruption was apparent during the subsequent eight months. Contrary to some suggestions, therefore, tolerance to the sleep-disruptive effects of the drug may be specific and incomplete, and extended REM rebound upon withdrawal is not a universal response.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00429175

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2

Digitale Medien

Effect of supercooling and freezing on photosynthesis in freezing tolerant leaves of Afroalpine ‘giant rosette’ plants (1987)

Bodner, M. ; Beck, E.

Springer

Oecologia 72 (1987), S. 366-371

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ISSN: 1432-1939

Schlagwort(e): Chlorophyll fluorescence ; Supercooling ; Frozen leaves ; Photosynthesis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The effect of supercooling and freezing on the photosynthetic capability of representatives of the permanent frost hardy giant rosette plants Dendrosenecio keniodendron, D. brassica and Lobelia telekii, of the tropical alpine regions was investigated with the non-invasive chlorophyll a fluorescence technique. While supercooling, normal chlorophyll a fluorescence kinetics exhibiting the sequence 0, I, (D), P, S, M, were recorded, however with some retardation of both, the fast and the slow characteristics as compared to those obtained at day-time temperature. As long as the leaves remained unfrozen, the rise of the variable fluorescence F ν from the level 0 to P was inversely related to a drop of the temperature from about 0°C to-8°C. The increase of F ν with lower temperature is understood to result from a decrease of the velocity of the quenching reactions while photoreduction of the primary electron acceptor appeared to be unimpeded. The second fluorescence maximum (M), usually interpreted to indicate the commencement of the biochemical reactions of photosynthesis was consistenly to be observed during supercooling. Fluoescence induction kinetics of frozen leaves showed only fast rise to presumably F max which was not followed by a significant decay for as long as 4 min. The lack of substantial quenching indicates that in the freeze-dehydrated state neither reoxidation of the primary acceptor nor energetization of the thylakoid membrane was accomplished. This effect however was immediately and fully reserved upon thawing of the leaves when the usual fluorescence induction kinetics as well as normal rates of CO2-uptake were observed. Thus the permanent frost-hardy afroalpine plants do not exhibit any even short-term memory effect of the nocturnal frost on such a delicate process as is photosynthesis.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00377565

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3

Digitale Medien

Methadone-induced changes in the visual evoked response recorded from multiple sites in the cat brain (1979)

Snyder, E. W. ; Shearer, D. E. ; Dustman, R. E. ; [weitere]

Springer

Psychopharmacology 63 (1979), S. 89-95

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ISSN: 1432-2072

Schlagwort(e): Methadone ; Visual evoked responses ; Cortical ; Subcortical ; Cats

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Visual evoked responses (VERs) and EEG were recorded following the i.p. administration of five doses of methadone (0.5–4 mg/kg) to 12 adult cats, which were implanted with cortical and subcortical electrodes. Additional cats, subjected to the same drug regimen, were used to evaluate plasma methadone concentrations. Doses of methadone that produced plasma concentrations between 80 and 190 ng/ml differentially affected VERs recorded from cortical and subcortical sites. Of the subcortical structures evaluated, the limbic system, specifically the hippocampus, was the most sensitive to the effects of the drug. These effects appeared to be primarily depressant. Responses recorded from the reticular formation and centromedian were affected only by the highest dose of methadone, while VERs recorded from cortical sites were reliably altered following the two highest doses and appeared to reflect both excitation and depression. Behavioral changes, however, were clearly evidenced in some cats at lower doses of methadone. Therefore, the data suggest (1) that those structures evaluated electrophysiologically did not reflect the full force of the drug's action as evidenced by its effect on behavior, (2) that cortical and subcortical recording sites have differential sensitivities, and (3) that one clearly defined, principal site of action of methadone is absent in the cat.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00426927

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4

Digitale Medien

Frost hardening and photosynthetic performance of Scots pine (Pinus sylvestris L.) needles. I. Seasonal changes in the photosynthetic apparatus and its function (1998)

Vogg, G. ; Heim, R. ; Hansen, J. ; [weitere]

Springer

Planta 204 (1998), S. 193-200

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ISSN: 1432-2048

Schlagwort(e): Key words: Chlorophyll ; Chlorophyll-binding protein ; Frost hardening ; Photosynthesis ; Pinus (frost hardening)

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract. Photosynthetic CO2 uptake, the photochemical efficiency of photosystem II, the contents of chlorophyll and chlorophyll-binding proteins, and the degree of frost hardiness were determined in three-year-old Scots pine (Pinus sylvestris L.) trees growing in the open air but under controlled daylength. The following conditions were compared: 9-h light period (short day), 16-h light period (long day), and natural daylength. Irrespective of induction by short-day photoperiods or by subfreezing temperatures, frost hardening of the trees was accompanied by a long-lasting pronounced decrease in the photosynthetic rates of one-year-old needles. Under moderate winter conditions, trees adapted to a long-day photoperiod, assimilated CO2 with higher rates than the short-day-treated trees. In the absence of strong frost, photochemical efficiency was lower under short-day conditions than under a long-day photoperiod. Under the impact of strong frost, photochemical efficiency was strongly inhibited in both sets of plants. The reduction in photosynthetic performance during winter was accompanied by a pronounced decrease in the content of chlorophyll and of several chlorophyll-binding proteins [light-harvesting complex (LHC)IIb, LHC Ib, and a chlorophyll-binding protein with MW 43 kDa (CP 43)]. This observed seasonal decrease in photosynthetic pigments and in pigment-binding proteins was irrespective of the degree of frost hardiness and was apparantly under the control of the length of the daily photoperiod. Under a constant 9-h daily photoperiod the chlorophyll content of the needles was considerably lower than under long-day conditions. Transfer of the trees from short-day to long-day conditions resulted in a significantly increased chlorophyll content, whereas the chlorophyll content decreased when trees were transferred from a long-day to a short-day photoperiod. The observed changes in photosynthetic pigments and pigment-binding proteins in Scots pine needles are interpreted as a reduction in the number of photosynthetic units induced by shortening of the daily light period during autumn. This results in a reduction in the absorbing capacity during the frost-hardened state.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004250050246

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5

Digitale Medien

Reassessment of root competition for P of field-grown maize in pure and mixed cropping (1988)

Fusseder, A. ; Kraus, M. ; Beck, E.

Springer

Plant and soil 106 (1988), S. 299-301

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ISSN: 1573-5036

Schlagwort(e): lupin ; maize ; phosphate ; root competition

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract Root competition for phosphate (P) in the field was calculated with maize i) as singly grown plants, ii) in pure cropping and iii) in mixed cropping with lupin. The experimentally determined parameters used for this purpose were thein situ root-distance pattern as registered by autoradiography and the P-depletion cylinder around a maize root as determined autoradiographically under radial diffusional flow. The results do not indicate any competition for P between roots of adjacently grown plants in either pure or mixed cropping. On the other hand, the P-depletion cylinders of approximately one third of the roots of an individual maize plant were found to overlap. However, when allowance was made for the concentration gradients within a depletion cylinder, the actual competition for phosphate was less than 1%.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02371230

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6

Digitale Medien

Development and replenishment of the P-depletion zone around the primary root of maize during the vegetation period (1987)

Kraus, M. ; Fusseder, A. ; Beck, E.

Springer

Plant and soil 101 (1987), S. 247-255

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ISSN: 1573-5036

Schlagwort(e): freeze-cutting ; dynamics ; depletion zone ; root longevity ; maize ; P-deficiency ; phosphate ; radioautography

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract The dynamics of the development and replenishment of P-depletion zones around the primary root of maize (Zea mays L. cv ‘Garbo’) was studied during a vegetation period (80 days) under greenhouse conditions in a loamy sand of low P-availability. A recently described freeze-cutting technique was used to determine radial diffusion of labelled phosphate to the primary root. The development of the depletion zone was biphasic. In the initial phase after two days of growth of the primary root in a soil layer labelled with33P a minimum of isotopically exchangeable P (EP) was observed which had decreased to about 30% of its original amount at the root surface. At that time the corresponding P-concentration in the soil solution was calculated to be as low as 5×10−7 M. The depletion zone had already spread 0.4 mm from the root surface. During the second phase, between the 10th and 20th day of plant growth the concentration of EP at the root surface increased slowly but did not change markedly. However, the depletion zone continued to spread and after the 20th day of growth reached its maximal diameter (1.07 mm from the root surface) but remained completely within the root hair cyclinder; the single root hairs never exceeded 1.14 mm in length. The biphasic growth of the depletion zone was probably caused by proton extrusion of the root tip. Acidification of the soil solution from pH 5.8 to about 3.9 results in an about 3-fold rise of the concentration of desorbed phosphate and might also have activated acidophilic P-translocators of the root during the initial phase. Anion over cation uptake normally prevailing during the later stage of root development might resulted in a rise of the soil pH within the root hair zone. Consequently P-availability, as well as P-uptake capacity declined, but P-uptake by the seminal root still continued until the 20th day. Subsequently, the P-concentration within the depletion zone increased again while simultaneously its extent was reduced until it was almost completely replenished after 60 days indicating a loss of P-uptake capacity of the primary root. Within the root tissue33P was accumulated to about twice the concentration of that in the undepleted soils. This accumulation corresponded to periods of high uptake due to the development of root laterals. In the root cortex a high P-content was observed during the first 30 days of growth. At the onset of the reproductive stage of the plant the P-content of the shoot and especially in the developing seeds rose considerably at the cost of phosphate stored in the root cortex. The accumulation of33P in the root tissue indicated that nutrient gain was mainly achieved during the early stages of plant development and that P was temporarily stored to some extent within the root system.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02370652

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7

Digitale Medien

Excited superdeformed band in146Gd (1991)

Rzaca-Urban, T. ; Strähle, K. ; Hebbinghaus, G. ; [weitere]

Springer

The European physical journal 339 (1991), S. 421-422

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ISSN: 1434-601X

Schlagwort(e): 21.10.−k ; 23.20.Lv ; 27.60.+j

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract A non-yrast superdeformed band has been found in146Gd using the110Pd(40Ar, 4n)146Gd reaction. The nuclear assignment was made from the analysis of an experiment using a backed target. This band and the previously identified yrast SD band are probably not signature partners.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01560647

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