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  • Hemofiltration  (2)
  • Lymphozytentransformation  (2)
  • 15N-tracer techniques  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 58 (1980), S. 1233-1241 
    ISSN: 1432-1440
    Keywords: Lymphocyte transformation ; Methylguanidine ; Phenol ; Urine metabolites ; Lymphozytentransformation ; Methylguanidin ; Phenol ; Urinmetabolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zur Differenzierung des bekannten hemmenden Effektes der potentiellen niedermolekularen „Urämietoxine“ Methylguanidin und Phenol auf die Lymphozytentransformation wurden beide Substanzen in steigender Konzentration Lymphozytenkulturen zugesetzt und3H-Thymidineinbau sowie LDH-Aktivität im Kulturmedium als Parameter des laufenden Lymphozytenuntergangs nach fünftägiger Inkubation gemessen. Für beide Substanzen findet sich sowohl in spontan transformierenden Kulturen als auch nach PHA-Stimulation eine dosisabhängige Transformationshemmung und ein ebenfalls dosisabhängiger Anstieg der LDH-Aktivität mit nahezu spiegelbildlichem Kurvenverlauf, so daß der Effekt beider Toxine offensichtlich in überwiegend cytotoxischer Herabsetzung der lymphozytären Überlebensdauer bestehen dürfte. In analoger Versuchsanordnung wurden weiterhin höhermolekulare Metabolite aus dem Urin von Gesunden und Patienten mit chronischer Niereninsuffizienz (kompensierte Retention) in steigender Konzentration Lymphozytenkulturen zugesetzt. Der auch hier zu registrierende dosisabhängige Abfall der spontanen und PHA-stimulierten Transformation sowie der spiegelbildliche LDH-Anstieg ist beim niereninsuffizienten Kollektiv in gleicher Konzentration gegenüber Gesunden leicht verringert, so daß eine Verschiebung zugunsten nichttoxischer Komponenten anzunehmen ist. Die um das 20–30fach höhere Exkretion dieser Metabolite bei diesen Patienten schließt aber eine Zuordnung zu den „Urämietoxinen“ im Sinne einer Retention im Serum aus.
    Notes: Summary In order to investigate the depressive effect of the hypothetical low molecular weight “uremic toxins” methylguanidine and phenol on lymphocyte transformation these substances were added to lymphocyte cultures with increasing concentrations.3H-thymidine uptake and LDH-activity in the supernatant culture medium as a parameter of continuous cell destruction were analyzed after incubation for 5 days. Both substances induced in spontaneous as well as in PHA-stimulated cultures dose-dependent depression of3H-thymidine uptake and a simultaneous increase in LDH-activity. Thus the effect of both toxins may be cytotoxic depression of lymphocyte viability. Furthermore in the same arrangement-way higher molecular weight metabolites from urine of healthy and chronic uremic persons were added in increasing concentrations to lymphocyte cultures. The same result: dose-dependent depression of transformation and increase of LDH-activity was slightly diminished by urine metabolites from uremic patients as compared to healthy persons. This may be due to a shift towards non-toxic compounds. But as these metabolites are excreted in 20–30 fold larger quantities in chronic renal insufficiency, an accumulation in the serum and classification as “uremic toxins” can be excluded.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Keywords: Uremia toxins ; lymphocyte transformation ; autohemolysis ; Urämietoxine ; Lymphozytentransformation ; Autohämolyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zur Frage einer toxischen Wirkung höhermolekularer Urinmetabolite durch Retention bei Urämie wurde der Effekt auf Lymphozytentransformation und Autohämolyse inkubierter Erythrozyten untersucht. Nach viertägiger Dialyse gegen Wasser wurde das lyophilisierte, nicht dialysable Retentat aus dem 24 Std Urin gesunder Personen mit einer Konzentration von 2,22 mg/ml in Medium TC 199 bzw. physiologischer Kochsalzlösung gelöst und davon steigende Mengen (0,1 bis 1,0 ml) Lymphozytenkulturen (3 × 106 Zellen in 4 ml Medium) und Erythrozyten (3 ml Vollblut nach Separation der Granulozyten) von 6 gesunden Blutspendern zugesetzt. Die durch Messung des3H-Thymidineinbaus nach fünftägiger Inkubation ermittelte spontane Lymphozytentransformation zeigte eine deutliche, dosisabhängige Hemmung bis auf 30,4% des Ausgangswertes, während der Abfall nach Stimulation mit 400 µg PHA nur bis 65,2% nachweisbar war. Die als Parameter des Zelluntergangs im Kulturmedium gemessene LDH-Aktivität wies in beiden Fällen einen dosisabhängigen Anstieg auf. Die negative Korrelation zu den3H-Thymidinwerten läßt als Hauptursache der verminderten Transformation einen vermehrten Zelluntergang annehmen. Die Autohämolyse der Erythrozyten zeigte einen dosisabhängigen Abfall bis auf 59,3% des Ausgangswertes. Höhermolekulare Urinmetabolite kommen demnach als Retentionsprodukte lediglich für die zytotoxische Teilwirkung urämischen Serums auf kultivierte Lymphozyten in Frage, während die gesteigerte Autohämolyse durch Toxine geringerer Molekülgröße ausgelöst wird.
    Notes: Summary Possible toxic effects of lyophilised not dialysable residue from urine of healthy persons obtained by 4 days dialysing against water were investigated. Therefore, the substance dissolved at a concentration of 2.22 mg/ml in Medium TC 199 respectively in physiological saline solution was added with increasing quantities (0.1 to 1.0 ml) to lymphocyte cultures (3 × 106 cells in 4 ml medium) and to erythrocytes (3 ml of blood after separation of granulocytes) from healthy persons. Spontaneous3H-thymidine uptake of the lymphocytes ascertained 5 days after beginning of incubation was markedly depressed with dependence upon the doses up to 30.4% of the control value, whereas only 65,2% was reached after stimulation with 400 µg PHA. In both cases LDH activity in the supernatant culture medium measured as a parameter of cell destruction showed a dose-dependent increase with inverse trend as compared to3H-thymidine uptake levels. This negative correlation may be due to impaired cell viability as the main cause for depressed lymphocyte transformation. The autohemolysis of the erythrocytes was diminished with dependence upon the doses until to 59.3% of the control value. Therefore, only cytotoxic effects of uremic serum on the lymphocytes may be due to higher molecular urine metabolites retained in uremia whereas increased autohemolysis will be induced by toxins of lower molecular weight.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 82 (1984), S. 407-413 
    ISSN: 1573-5036
    Keywords: Carbon partitioning ; Field bean ; Mutant lines ; Nitrogen partitioning ; 15N-tracer techniques ; Symbiotic nitrogen fixation ; Vicia faba minor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Homozygous mutant lines of field bean selected for (a) improved yielding potential and (b) altered plant architecture and/or physiological response were tested for symbiotic nitrogen fixing ability under field conditions in comparison with their parent cultivar.15N-tracer techniques were applied to determine %N derived from atmosphere. Data were collected on assimilate and nitrogen accumulation and distribution among various plant parts during two stages of reproductive growth. Symbiotic nitrogen fixation was closely correlated with total plant top biomass and nitrogen yield. A similar close association was found between crop yield and nitrogen harvest index. Both harvest indices tended to be negatively correlated with stage of maturity and with the amount of N derived from air per unit of area. The generally high %N derived from symbiotic N2 fixation and its comparatively small variability implies that this parameter may be difficult to improve inVicia faba under field conditions. It is concluded, that the main genetic potential for improving the amount of biological nitrogen fixation in this crop depends upon factors that promote high photosynthetic productivity and efficient N-use under appropriate agronomic conditions and with effective rhizobial associations. The establishment of rational ideotypes with a possitive impact on yield appears to be of practical significance for increasing the amount of symbiotically fixed nitrogen.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1612-1112
    Keywords: Sialyl compounds ; Uremic toxins ; Hemofiltration ; Renal failure ; NMR-spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hemofiltrate of patients with end stage renal disease is a source of sialyl compounds of unusual composition which accumulate in uremia. The large volumes involved (20–30l), are concentrated and desalted by modified reverse osmosis using membranes with a nominal cut-off of 500 D. The transport of the individual solutes during this process is monitored by reversed-phase HPLC of the permeates and retentates, respectively. By a combination of size-exclusion and ion-exchange chromatography 11 sialyl compounds are isolated preparatively. All structures have been determined using one and two dimensional NMR spectroscopy, enzymatic degradation and FAB mass spectrometry.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: High-performance liquid chromatography ; Size exclusion chromatography ; Membrane permeability ; Hemofiltration ; Renal failure ; Uremic toxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The present study shows that liquid chromatography, especially as high performance size exclusion chromatography, is a useful tool to characterize newly developed highly permeable membranes, which are used for continuous arteriovenous hemofiltration (CAVH) of patients with renal failure. The molecular weight distribution in the ultrafiltrates of three hemofilters are compared using three different chromatographic systems. Especially in the region of the so-called “higher” molecular weight uremic toxins (MW above 2000 Dalton), the elution patterns of the filtrates show typical membrane-dependent differences. As we have shown earlier, the elimination of these higher molecular weight fractions might be of clinical relevance, as they contain inhibitors of DNA-synthesis in vitro.
    Type of Medium: Electronic Resource
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