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  • Pediatric intensive care  (2)
  • Ventriculography  (2)
  • oral administration  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Biological effects of encapsulated insulin on transfected Chinese hamster ovary cells (1995)
    Springer
    Diabetologia 38 (1995), S. 180-186 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Key words Insulin pharmacology ; insulin metabolism ; oral administration ; dose-response relationship ; cultured cells.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Oral administration of insulin incorporated into the wall of isobutylcyanoacrylate nanocapsule to diabetic rats induces a long-lasting normalization of their fasting glycaemia. In this study, we examined the biological action of encapsulated insulin on DNA and glycogen syntheses in Chinese hamster ovary cells transfected with the human insulin receptor gene. In the 10–11 mol/l – 10–9 mol/l concentration range, encapsulated insulin elicited responses comparable to those induced by native insulin: at 10–9 mol/l, the rates of glycogen and DNA synthesis were enhanced by factors 3 and 2.5, respectively. Encapsulated insulin at 10–7 mol/l evoked receptor desensitization although it did not induce receptor down-regulation and did not alter receptor recycling for up to 6 h. Chloroquine decreased the action of native insulin on glycogen synthesis, but did not affect the dose-response characteristics of encapsulated insulin. Acid-washing of the cells after 1 h of stimulation decreased maximal insulin responsiveness and provoked a dose response curve for encapsulated insulin similar to that of the native hormone. Direct measurement of effective insulin binding activity showed that encapsulated insulin (at 10–8 and 10–7 mol/l) was withdrawn from the incubation medium 5–8 times less efficiently than native insulin. These data are in agreement with previous results showing that the polymeric wall protects encapsulated insulin from degradation. Persistence of intact encapsulated insulin inside and outside the cell may result in modifying signalling events and thus be responsible for the observed cellular desensitization.[Diabetologia (1995) 38: 180–186]
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00400092
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  • 2
    Digitale Medien
    Digitale Medien
    Biological effects of encapsulated insulin on transfected Chinese hamster ovary cells (1995)
    Springer
    Diabetologia 38 (1995), S. 180-186 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Insulin pharmacology ; insulin metabolism ; oral administration ; dose-response relationship ; cultured cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Oral administration of insulin incorporated into the wall of isobutylcyanoacrylate nanocapsule to diabetic rats induces a long-lasting normalization of their fasting glycaemia. In this study, we examined the biological action of encapsulated insulin on DNA and glycogen syntheses in Chinese hamster ovary cells transfected with the human insulin receptor gene. In the 10−11 mol/l–10−9 mol/l concentration range, encapsulated insulin elicited responses comparable to those induced by native insulin: at 10−9 mol/l, the rates of glycogen and DNA synthesis were enhanced by factors 3 and 2.5, respectively. Encapsulated insulin at 10−7 mol/l evoked receptor desensitization although it did not induce receptor down-regulation and did not alter receptor recycling for up to 6 h. Chloroquine decreased the action of native insulin on glycogen synthesis, but did not affect the dose-response characteristics of encapsulated insulin. Acid-washing of the cells after 1 h of stimulation decreased maximal insulin responsiveness and provoked a dose response curve for encapsulated insulin similar to that of the native hormone. Direct measurement of effective insulin binding activity showed that encapsulated insulin (at 10−8 and 10−7 mol/l) was withdrawn from the incubation medium 5–8 times less efficiently than native insulin. These data are in agreement with previous results showing that the polymeric wall protects encapsulated insulin from degradation. Persistence of intact encapsulated insulin inside and outside the cell may result in modifying signalling events and thus be responsible for the observed cellular desensitization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00400092
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  • 3
    Digitale Medien
    Digitale Medien
    Assessment of neonatal ventilator performances (1995)
    Springer
    Intensive care medicine 21 (1995), S. 753-758 
    Details
    ISSN: 1432-1238
    Schlagwort(e): Artificial ventilation ; Pediatric intensive care ; Positive end-expiratory pressure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objective To analyze efficiency and reliability of 4 modern neonatal ventilators under difficult test conditions. The ventilators tested were: Babylog 8000 (Dräger Medical), BP 2001 (Bear Medical Systems), Sechrist IV 100 B (Sechrist Industries), Infant Star (Infrasonics INC). Measurements and results Gas flow generation was tested by comparison of preset flow values with no resistance in the circuit to flow values obtained during interposition of a resistance in the inspiratory circuit. A decrease in gas flow was observed when interposition of a resistance in the inspiratory circuit increased peak inspiratory pressure to 60 cmH2O (gas flow decreased by 8% to 24% depending on the ventilator tested). The pressure limiting valve and the positive end-expiratory pressure valve were also evaluated in order to test their behaviour under different flow conditions. Flow-dependence of the pressure was noted for all ventilators except Babylog 8000. Assessment of the reliability of pressure monitoring revealed either ‘under’ or ‘over’ estimation of peak inspiratory pressure and positive end-expiratory pressure depending on the ventilator tested. Conclusion For the best clinical use of mechanical ventilators, neonatologists should be aware of these limitations. Therefore a regular assessment of ventilator performance and monitoring reliability is recommended.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01704743
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  • 4
    Digitale Medien
    Digitale Medien
    Assessment of high-frequency neonatal ventilator performances (1997)
    Springer
    Intensive care medicine 23 (1997), S. 208-213 
    Details
    ISSN: 1432-1238
    Schlagwort(e): Key words High-frequency ventilation ; Pediatric intensive care
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objective: To assess the efficacy and reliability of neonatal high-frequency ventilators. Design: Bench evaluation of neonatal high-frequency ventilators. Setting: Physiology department and university hospital neonatal intensive care unit. Interventions: HFV-Babylog 8000 (Dräger Medical), OHF 1 (Dufour), and SensorMedics 3100A (SensorMedics) ventilators were connected to a neonatal test-lung. Tidal volume, peak-to-peak pressure amplitude, and mean airway pressure were measured for several ventilator settings, endotracheal tube sizes, and lung compliances. Measurements and results: Increasing peak-to-peak pressure resulted in a linear increase in tidal volume delivery in the 0–30% range of maximum amplitude. No significant increase in tidal volume was observed with the HFV-Babylog8000 when pressure amplitude was above 50%. The maximum tidal volume delivered was substantially smaller with the HFV-Babylog8000 than with the OHF1 or SensorMedics3100A. Tidal volume increased with endotracheal tube size with all three ventilators. Increasing test-lung compliance resulted in lower tidal volumes only with OHF1. Decreasing mean airway pressure was responsible for a decrease in tidal volume delivery with HFV-Babylog8000. Conclusion: We found that under our test conditions two of the three ventilators delivered adequate tidal volumes at the usual frequency of 15Hz, regardless of the size of the endotracheal tube and of the mechanical properties of the respiratory system. When lung compliance increased or mean airway pressure decreased, both of which are common events during the recovery phase of hyaline membrane disease, we found that the intrinsic properties of two of the ventilators tested were responsible for a decrease in tidal volume. This decrease may account for some cases of heretofore unexplained hypercapnia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001340050318
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  • 5
    Digitale Medien
    Digitale Medien
    Technetium-99m labelled human serum albumin for ventriculography: a comparative evaluation of six labelling kits (1993)
    Springer
    European journal of nuclear medicine 20 (1993), S. 465-472 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Technetium-99m labelled human serum albumin ; Labelling kit ; Ventriculography ; Blood pool agent
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In this study we have compared the characteristics of six labelling kits for the preparation of technetium-99m labelled human serum albumin (99mTc-HSA) and evaluated the usefulness of the various 99mTc-HSA preparations as blood pool tracer agents. The amount of the principal ingredients, i.e. HSA and stannous ions, varies largely between the studied kits and this is probably a reason for the observed differences in the labelling rate. Analysis of the reaction mixtures after labelling of the respective kits with 99mTc showed in each preparation the presence of four to five radioactive components in variable relative amounts. The retention time of the main component on size-exclusion high-performance liquid chromatography (SEC-HPLC) was identical for all preparations. Biodistribution of the HPLC-isolated fractions was studied in mice. The components with the shortest and longest retention times on HPLC show poor retention in the plasma. The three intermediate fractions, including the principal peak, are initially retained relatively well in the blood (60%–70% of the injected dose after 10 min), but clearly to a lower degree than iodine-125 labelled HSA. Moreover, they diffuse out of the vascular compartment at a much higher rate than 125I-HSA. The biological behaviour of the main component of the various preparations was clearly different, despite the identical retention time on SEC-HPLC. Study of the total preparations in mice and a rabbit showed that two of them are cleared rapidly from the blood and cannot be considered valuable blood pool tracers. Diffusion of the other preparations out of the blood is slower but also considerable and compromises their use for ventriculography.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175158
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  • 6
    Digitale Medien
    Digitale Medien
    Technetium-99m mercaptoalbumin as a potential substitute for technetium-99m labelled red blood cells (1993)
    Springer
    European journal of nuclear medicine 20 (1993), S. 473-482 
    Details
    ISSN: 1619-7089
    Schlagwort(e): 99mTc-labelled human serum albumin ; 99mTc-mercaptoalbumin ; Ventriculography ; 99mTc-labelled erythrocytes ; 99mTc-DMP-HSA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Technetium-99m labelled red blood cells (99mTc-RBCs) are far superior to 99mTc-labelled human serum albumin (99mTc-HSA) for radionuclide ventriculography, but their labelling is more complex, time consuming and risk bearing (in vitro labelling) or suffers from interference by some medications (in vivo labelling). We have now modified HSA by the introduction of mercapto groups with the purpose of preparing stable and practical 99mTc-mercaptoalbumin with long retention in the vascular system, that could replace 99mTc-RBCs. HSA was incubated with N-succinimidyl S-acetylthioacetate (SATA) or N-succinimidyl 2,3-di(S-acetylthio) propionate (SATP) to introduce a chain containing one or two protected sulfhydryl groups on some of the lysine amino groups. After purification by size-exclusion chromatography (SEC), the mercapto groups were deprotected by incubation at alkaline pH or by treatment with hydroxylamine. The reaction products were used with or without SEC purification for direct or exchange labelling experiments with 99mTc at neutral pH. SEC-HPLC was used to determine labelling yields and to isolate pure 99mTc-mercaptoalbumin. Stable 99mTc-mercaptoalbumin complexes could be formed in 90%–95% yield after coupling albumin with SATA or SATP in all molar ratios used followed by deacetylation in one of the mentioned conditions. The most favourable results were obtained after reaction of SATA or SATP with HSA in a 25: 1 ratio and deprotection with NH2OH. The stability of the resulting 99mTc-mercaptoacetyl-albumin (99mTc-MAHSA) and 99mTc-dimercaptopropionyl-albumin (99mTcDMP-HSA) and their retention in vivo in plasma of mice and rabbits are clearly higher than that of conventional 99mTc-HSA preparations. 99mTc-DMP-HSA approaches the behaviour of 125I-HSA quite well in both animal species. A preliminary study with 99mTc-DMP-HSA in a volunteer showed a retention in the vascular compartment almost identical to that of 99mTc-RBCs and clearly higher than that of a common 99mTc-HSA preparation. The results indicate that these 99mTc-mercaptoalbumins and especially 99mTc-DMP-HSA are very promising as a practical alternative to 99mTc-RBCs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175159
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