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  • tropical pond  (2)
  • Acartia clausi  (1)
  • Insulin resistance  (1)
  • *Tumor Suppressor Proteins
  • 74.50+r
  • 1995-1999
  • 1990-1994  (4)
  • 1955-1959
  • 1994  (4)
Sammlung
Verlag/Herausgeber
Erscheinungszeitraum
  • 1995-1999
  • 1990-1994  (4)
  • 1955-1959
Jahr
  • 1
    ISSN: 1432-1041
    Schlagwort(e): Hydrocortisone ; Methylprednisolone ; Insulin resistance ; glucose metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Glucocorticoid-induced glucose intolerance and insulin resistance are dependent on the type of steroid, its dose and route of administration. Although the intravenous (i.v.) route is used mainly, the effects of different steroids have so far been compared using the oral route. The present study was therefore planned to compare the effects on glucose metabolism of hydrocortisone (HC) and methylprednisolone (MP) administered i.v. at equivalent antiinflammatory doses in healthy subjects. Eighteen healthy volunteers with normal glucose tolerance, divided into three groups (A,B,C) matched for age, sex and body mass index were subjected to oral glucose tolerance tests (oGTT) 12 h after HC or MP i.v. injection. The two tests were performed at a 1-month interval and in random sequence. Group A received low doses (HC 100 mg, MP 20 mg), group B intermediate doses (HC 200 mg, MP 40 mg) and group C high doses (HC 400 mg, MP 80 mg). Serum glucose, insulin and C-peptide were measured during both fasting and oGTT. Serum glucose values were not significantly different after HC or MP, during both fasting and oGTT. However, there was a positive correlation between fasting serum glucose or the area under the glucose curve and the dose·kg−1 body weight of HC (r=0.748; r=0.462) and MP (r=0.708; r=0.736). Serum insulin values were significantly higher after MP than after HC when fasting (A: 115 vs 223; B: 95 vs 215, C: 158 vs 268 pmol·l−1) and as area under the oGTT curve (A: 57.8 vs 87; B: 48.5 vs 92.1; C: 57.8 vs 94.5 pmol·l−1·2 h). In contrast, serum C-peptide values were not significantly different after HC or MP, neither fasting nor as area under the insulin curve. Fasting C-peptide/insulin molar ratio was significantly lower after MP than HC at the three doses administered. In conclusion the dose-related decreases in glucose tolerance are more marked after a single i.v. injection of MP than HC at the same anti-inflammatory dose, MP 20 or 40 mg as well as HC 100 or 200 mg do not impair glucose tolerance, but the former is associated with higher serum insulin levels, suggesting insulin resistance. MP-induced hyperinsulinaemia seems to be mainly due to reduced hepatic insulin extraction.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1573-5125
    Schlagwort(e): bacteria ; zooplankton ; grazing ; tropical pond ; eutrophic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The aim of the study was to determine whether bacteria could be a substantial source of carbon for zooplankton and whether the grazing pressure of these metazoan filter-feeders could influence the fate of bacterial production. Eight grazing experiments using natural bacteria labelled with3H thymidine were conducted in a tropical pond (Ivory Coast) during various phases of biological colonization (rotifer-dominated and copepod-dominated phases of the colonization). Higher grazing and clearance rates were observed with rotifers (Brachionus plicatilis andHexarthra intermedia), while very low values were obtained when the cyclopoid copepodApocyclops panamensis was dominant. Less than 1% of the bacterial production was harvested when copepods were dominant, whileB. plicatilis consumed up to 36% of this production. However, this consumption of bacteria appeared to contribute only to an insignificant proportion of the daily carbon intake (e.g. 0.9 to 7.1% of body carbon for rotifers). The low contribution of bacteria in the nutrition of zooplankton is discussed in terms of their cell size and their relative abundance in the total amount of seston available.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1573-5117
    Schlagwort(e): Acartia clausi ; copepod ; tropical lagoon ; metabolic budgets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Simultaneous measurements of respiration, excretion and production rates were carried out several times over a year period at five representative stations of the Ebrié Lagoon. Assuming a constant assimilation efficiency rate of 69.4%, we derived metabolic budgets for carbon, nitrogen and phosphorus. Daily specific ingestion rates calculated were rather generally high, and ranged between 54 and 159% of body carbon, between 26 and 102% of body nitrogen and between 108 and 307% of body phosphorus. Regional and seasonal variations depended mainly upon variations in trophic conditions. Curvilinear relationships between ingestion production, or net production efficiency K2, and food concentration (as chlorophyll-a + phaeopigments) showed that food could have been a limiting factor. Furthermore, K2 were low when compared with data from the literature (mean of 21% in carbon, 39% in nitrogen and 11% in phosphorus). Complementary laboratory experiments carried out on adults fed with enriched natural particles or algal cultures (Tetraselmis sp. or Dunaliella sp.) showed similar production (egg-production) vs food concentration curvilinear relationships as in the field. However, considerably higher maximal ingestion and production rates were obtained for animals fed algal cultures suggesting that optima for food acquisition and transformation were not reached in field conditions. Consequently, A. clausi, which represents more than 50% of the zooplankton biomass, appears to be rather inefficient in transforming the abundant particulate organic matter produced in the lagoon. This results from its high level of metabolic expenditure through respiration or excretion (about 50% of ingestion in terms of carbon) and from the small size and poor trophic value of food particles (high percentage of detritus).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1573-5117
    Schlagwort(e): bacteria ; phytoplankton ; protozoa ; rotifera ; cyclopoids ; succession ; recolonization ; tropical pond
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The structure of a planktonic community was studied in April 1990 for 24 days (D1 to D24) during the natural recolonization of a tropical pond (Côte d'Ivoire) made azoic by emptying and liming (D0). Abundances of bacterioplankton, phytoplankton, protozoans and zooplankton were studied twice daily, whereas hydrological descriptors (temperature, conductivity, oxygen, pH, dissolved nutrients, sestonic weights) were recorded several times daily. After the pond treatment, the natural refilling from groundwater began immediately. The microheterotrophic (bacteria, flagellates, ciliates), phytoplanktonic (Coelastrum microsporum) and zooplanktonic (the rotifers Brachionus plicatilis and Hexarthra intermedia) communities were first based on opportunist species favored by the initially large nutritive availability. This close link with the trophic resources induced their rapid elimination, as soon as the food source was depleted by overconsumption. Due to liming effects, great amounts of degradable organic compounds allowed bacterial communities to develop before phytoplankton. This biological succession was first based on a catastrophic-type system, successively controlled by bottom-up factors (proliferation) and top-down factors (species collapse). Then, the colonization was completed with the development of secondary consumers (last stages of Apocyclops panamensis and chironomids). The progressive complexity of the system ensured the attenuation of the disturbing events. Finally, due to volume variations of the pond along the recolonization steps, the effects of the dilution process on bacteria and chlorophyll biomass were studied. In a context of non-limiting nutrient substrata, the microbial community was able to colonize the new volume within a few hours. Phytoplankton showed a more complex adaptation to the volume increase, with mixed effects of grazing, sedimentation and diurnal productions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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