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  • 1
    ISSN: 1432-1971
    Schlagwort(e): Normal neonates ; Right ventricular systolic time intervals ; Left ventricular systolic time intervals ; Heart rate ; Longitudinal study
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary To determine the influence of heart rate (HR) on systolic time intervals (STI) in neonates, serial measurements of right ventricular (RVSTI) and left ventricular systolic time intervals (LVSTI) were made on 30 healthy term newborn infants at age 4–8 h, 24–30 h, eight days, and four weeks. STI was related to HR and age. Age-related changes were similar to previously reported results. The preejection periods (RPEP and LPEP) significantly shortened with increasing age, whereas the right and left ventricular ejection times (RVET and LVET) were unrelated to age. RPEP was unrelated to HR, but tended to be prolonged in restless infants. With increasing HR, RVET decreased and RPEP/RVET increased in all age groups, but less at four weeks. A rise in HR of 50/min resulted in an increase of RPEP/RVET by 26% of the mean value at age 4–8 h and by 20% at four weeks. In 14 infants, RVSTI was recorded during a change in HR. In all these infants, RPEP and RPEP/RVET increased with increasing HR. We conclude that HR-related changes of RVSTI in neonates are different from those in older subjects. It should be considered that in neonates elevated values of RPEP/RVET, suggesting increased pulmonary vascular resistance, may be caused by high HR and unrest.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 474-478 
    ISSN: 1432-1912
    Schlagwort(e): (R)-Propranolol ; (S)-Propranolol ; Betaadrenoceptor antagonists ; Stereoselectivity ; Iodocyanopindolol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In a randomized, double-blind, placebo-controlled, cross-over study 24 healthy volunteers were examined before and 2 h after oral administration of 80 mg (R,S)-, 40 mg (R)- and 40 mg (S)-propranolol · HCI; 8 of them received placebo in an additional run. During exercise on a bicycle ergometer and a rest period the rate pressure product was decreased by 80 mg (R,S)-propranolol · HCl (−32.8%p 〈 0.0001) and 40 mg (S)-propranolol · HCl (−32.3%;p 〈 0.0001), whera 40 mg (R)-propranolol · HCl as well as placebo showed no effect. corresponding binding inhibition experiments using (−)-(125I)iodocyanopindolol in a sarcolemma-enriched cardiac membrane preparation yielded a eudismic ratio of 179 for (S)- over (R)-propranolol. 2 h after oral application, stereospecific HPLC analysis revealed different individual concentrations in plasma of (R)-(22.3 ± 21.7 ng/ml) and (S)-propranolol (30.4 ± 26.9 ng/ml) when 80 mg of (R,S)-propranolol · Hcl was administered. The plasma levels were similar when 40 mg of the pure enantiomer of (R)- (22.7 ± 20.3 ng/ml) or (S)-propranolol · HCl (28.7 ± 22.5 ng/ml) was applied. (R)- and (S)-propranolol are two substances with different pharmacodynamic and pharmacokinetic properties. As there are methods available to produce the optically pure enantiomers, they should be used rather than the racemic mixture.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 3 (1989), S. 153-156 
    ISSN: 0269-3879
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: An automated column-switching HPLC system is described for the simultaneous determination of midodrine, an alpha-adrenergic stimulating drug, and its active metabolite, ST-1059. Serum or plasma (850 μ L) is directly injected onto a RP 18 (30 μm particle size) pre-column (9 × 4 mm ID) which acts as an on-line liquid-solid extractor and analyte enrichment system. The injection is followed by washing steps. The fraction containing the analytes is transferred onto an analytical RP18 column via step gradient elution where the final analysis is performed. Fluorescence detection is used (λex 290 nm and λem 322 nm), and method detection limits of 0.8 ng/mL plasma were reached. These were sufficiently low to determine the plasma concentration-time profiles for both compounds following oral administration of 2.5 mg and 5 mg midodrine hydrochloride. The assay in serum or plasma was linear in the range of 1 to 15 ng analyte/mL, the recovery was 〉95%, and the reproducibility was sufficient. The assay was rugged and was maintained by routinely changing the home-made, dry packed pre-column every 20th serum injection.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Fresenius' Zeitschrift für analytische Chemie 333 (1989), S. 730-730 
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Microchimica acta 95 (1988), S. 123-126 
    ISSN: 1436-5073
    Schlagwort(e): diffuse reflectance ; infrared spectroscopy ; quantitative analysis ; HPLC phase characterization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Chemically modified silica gels are investigated with respect to identity, purity and degree of surface coverage using diffuse reflectance FTIR (DRIFT) Spectroscopy. We report the results for two bonded HPLC phases, pyrene butyric acid propylamido- and octadecyl-groups grafted on irregular porous silica gel. For quantitative determination calibration standards are prepared by adsorbing structurally similar ligand compounds onto the surface of the silica gel; these coated materials give linear calibration curves up to a concentration of 1 mmol/g modified silica gel.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 0935-6304
    Schlagwort(e): High-performance liquid chromatography ; β-methyl amino acids ; enantioseparation ; quinine-derived chiral stationary phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A quinine-derived chiral anion-exchange stationary phase was used for the direct high-performance liquid chromatographic separation of the enantiomers of the N-protected unusual β-substituted α-amino acids, β-methylphenylalanine, β-methyltyrosine, β-methyltryptophan, and β-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. The readily prepared 2,4-dinitrophenyl and tert-butyloxycarbonyl derivatives were well separated, and in most cases the separation of all four stereoisomers of these β-methyl-α-amino acids could be obtained in one chromatographic run. The elution sequences of the enantiomers of the different derivatives were determined and revealed a dependence on the type of the N-protecting group. In this context, the effects of different protecting groups (acetyl, tert-butyloxycarbonyl, benzoyl, 3,5-dinitrobenzoyl, benzyloxycarbonyl, 3,5-dinitrobenzyloxycarbonyl, 2,4-dinitrophenyl, and 9-fluorenylmethoxycarbonyl) on the chromatographic behavior were investigated.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1203-1205 
    ISSN: 0009-2940
    Schlagwort(e): AM1 calculations ; Chloralide ; Dioxolane ; Force-field calculations ; Tartaric acid ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Isolation of a third diastereoisomer (1c) of (R,R)-tartaric acid chloralide is described. A comparison of structural data derived by X-ray analysis with calculated parameters is given. Structures are generated by the ALCHEMY force-field program as well as by AM1 calculations.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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