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  • 1
    Electronic Resource
    Electronic Resource
    Polymerase chain reaction detects hepatitis B virus DNA in paraffin-embedded liver tissue from patients sero- and histo-negative for active hepatitis B (1992)
    Springer
    Virchows Archiv 420 (1992), S. 11-15 
    Details
    ISSN: 1432-2307
    Keywords: Hepatitis B ; Polymerase chain reaction ; Paraffin sections ; Liver biopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The polymerase chain reaction (PCR) was used to analyse tissues from paraffin blocks of liver needle biopsies retrospectively. Biopsies of 29 patients with proven HBsAg and HBcAg expression in liver tissue and of 8 healthy volunteers served as positive (group 1) and negative tissue controls (group 2), respectively. These were compared with 16 patients with proven HBsAg expression in liver but lack of HBcAg (group 3), with 23 patients with anti-HBc as the only hepatitis B virus (HBV)-related marker (group 4) and with 21 patients with liver disease and without HBV markers in tissue or serum (group 5). PCR detected HBV sequences in all cases of the positive control group and in 94% of group 3, in 65% of group 4, and in 71.4% of group 5, whereas all healthy volunteers were negative. Our data show that PCR is able to detect HBV-DNA sequences in virtually all patients with active viral antigen expression but also in a high proportion of hepatitic patients who are silent for active HB but may or may not show signs of a contact with the HBV. Thus, PCR for HBV-DNA in paraffin sections might become a useful tool for identifying patients carrying HBV-DNA but not expressing HBV antigens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605978
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  • 2
    Electronic Resource
    Electronic Resource
    Error rates in quadratic discrimination with constraints on the covariance matrices (1994)
    Springer
    Journal of classification 11 (1994), S. 101-120 
    Details
    ISSN: 1432-1343
    Keywords: Common principal components ; Linear Discriminant Function ; Monte Carlo Simulation ; Proportional Covariance Matrices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In multivariate discrimination of several normal populations, the optimal classification procedure is based on quadratic discriminant functions. We compare expected error rates of the quadratic classification procedure if the covariance matrices are estimated under the following four models: (i) arbitrary covariance matrices, (ii) common principal components, (iii) proportional covariance matrices, and (iv) identical covariance matrices. Using Monte Carlo simulation to estimate expected error rates, we study the performance of the four discrimination procedures for five different parameter setups corresponding to “standard” situations that have been used in the literature. The procedures are examined for sample sizes ranging from 10 to 60, and for two to four groups. Our results quantify the extent to which a parsimonious method reduces error rates, and demonstrate that choosing a simple method of discrimination is often beneficial even if the underlying model assumptions are wrong.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01201025
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  • 3
    Electronic Resource
    Electronic Resource
    Three Saponins, a Steroid, and a Flavanol Glycoside from Achyrantes aspera (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 195-204 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Saponins; NMR spectroscopy; Natural products; Structure elucidation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  Three bisdesmosidic saponins, 20-hydroxyecdysone, and quercetin-3-O-β-D-galactoside were isolated from the methanol extract of the aerial parts of Achyranthes aspera L. (Amaranthaceae). Their structures were established on the basis of NMR spectroscopic analysis; the complete 1H and 13C assignments of the compounds were achieved by means of 2D NMR studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010306
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  • 4
    Electronic Resource
    Electronic Resource
    A Diterpene, a Flavonol Glycoside, and a Phytosterol Glycoside from Securidaca longipedunculata and Entada abyssinica (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 401-408 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Securidaca longipedunculata; Entada abyssinica; Leguminosae; Polygalaceae; Diterpene; Flavonol glycoside.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The MeOH extract of the stem bark of Entada abyssinica and of the leaves and stem bark of Securidaca longipedunculata yielded a diterpene, a flavonol glycoside, and a phytosterol glycoside. Their structures were established on basis of NMR spectroscopic analysis; the complete 13C and 1H assignment of the compounds was achieved by means of 2D NMR studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007060050321
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  • 5
    Electronic Resource
    Electronic Resource
    Reproducibility of the data determined by scanning laser polarimetry (1996)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 234 (1996), S. 628-632 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract • Background: Scanning laser polarimetry is a tool for measuring the retinal nerve fiber layer: both its cross-sectional surface (polarimetric data analysis) and its thickness (mean sector values). • Methods: Two observers examined 56 normal volunteers twice by means of scanning laser polarimetry (Nerve Fiber Analyzer type 1, software version 1.6). Measurements of the retinal nerve fiber layer were carried out in four equal sectors of a circle around the optic nerve head. The measured values of the sectors and the calculated ratios among them were used for statistical analysis. Interobserver and intraobserver reproducibility were analyzed following a balanced random three-way cross classification with interactions. Interobserver reproducibility was defined as the part of variance not influenced by the observers. Intraobserver reproducibility was defined as the part of variance not influenced by the time. • Results: For repeated measurements of the retinal nerve fiber layer, better intraobserver than interobserver reproducibility was found (0.57–0.79 vs 0.11–0.44). The interobserver reproducibility was improved (0.24–0.65) in comparison to the intraobserver reproducibility (0.32–0.68) by calculating the ratios of the measured values. • Conclusion: The instrument is clinically useful only if used by the same observer. If measurements are performed by different observers the ratios of the measurements must be used. Further development in the apparatus is needed to improve interobserver reproducibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185296
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  • 6
    Electronic Resource
    Electronic Resource
    Simulationsuntersuchungen zur Evaluierung der Kapazität eines neuen Fertigungssystems (1992)
    Springer
    OR spectrum 14 (1992), S. 193-199 
    Details
    ISSN: 1436-6304
    Keywords: Simulation ; Kapazitätsplanung ; Reihen-folgeplanung ; Simulation ; capacity planning ; sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Summary This paper describes the use of discrete simulation to determine the capacities and production rates of a new two-stage production facility. Due to lack of experience, it is necessary to determine the capacity of each individual machine in the production process, as well as the capacity of each production stage. The production rate of the entire facility is established on the basis of individual capacities. The analysis of the production system shows that bottlenecks are highly dependent on the actual production mix. The production limitations of each stage are therefore seperately determined and they are further used as restrictions in the shoploading procedure. In addition, a heuristic solution procedure for establishing a production program by taking all simulated capacity restrictions into account is presented.
    Notes: Zusammenfassung In dieser Arbeit wird die Verwendung der diskreten Simulation zur Bestimmung von Kapazitäten und maximalen Produktionsmengen einer neu errichtenden Fertigungsanlage beschrieben. Aufgrund fehlender Erfahrungswerte ist es dabei notwendig, die Kapazität jeder einzelnen Maschine im Produktionsprozeß bzw. jeder Produktionsstufe zu bestimmen. Davon ausgehend wird die maximale Produktionsmenge der gesamten Fertigungsanlage ermittelt. Die Analyse des Fertigungssystems zeigt, daß die Lage der Engpässe sehr stark vom tatsächlichen Produktionsprogramm abhängig ist. Aus diesem Grund wird das maximale Kapazitätsangebot der einzelnen Produktionsstufen getrennt bestimmt und als Restriktionen bei der Einlastung der einzelnen Aufträge verwendet. Ein heuristisches Verfahren zum Festlegen des Produktionsprogramms unter Beachtung aller durch verschiedene Simulationsläufe ermittelten Restriktionen bildet den Abschluß der Arbeit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01733402
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  • 7
    Electronic Resource
    Electronic Resource
    Capillary electrophoretic chiral resolution of vicinal diols by complexation with borate and cyclodextrin: Comparative studies on different cyclodextrin derivatives (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 153-156 
    Details
    ISSN: 0899-0042
    Keywords: chiral separation ; β-cyclodextrin derivatives ; capillary electrophoresis ; vicinal diols ; borate complexation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary electrophoretic enantioseparation of compounds containing vicinal diol groups have been investigated using different β-cyclodextrin (CD) derivatives and borate as a background electrolyte. Both native β-CD and several β-CD derivatives are examined. Chiral recognition is attributed to both enantioselective inclusion of the analyte into the chiral cavity of the CD and complexation with borate. The influence of concentration of the chiral selector, pH, and organic modifiers on the resolution was studied. Four diols were baseline separated. Chirality 9:153-156, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    UV-spektroskopische Mehrkomponenten-Analyse: Anwendung auf Nucleinsäure-Bestandteile (1980)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 300 (1980), S. 381-386 
    Details
    ISSN: 1618-2650
    Keywords: Analyse von Nucleinsäuren ; Cytosin, Uracil, Cytidin. Uridin ; Spektralphotometrie, UV ; Mehrkomponentenanalyse, Desaminierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Möglichkeiten der Verwendung der UV-spektroskopischen Mehrkomponenten-Analyse zur Untersuchung von Cytosin/Uracil- und Cytidin/Uridin-Gemischen sowie zur Untersuchung der Desaminierung von Cytosin, Cytidin und Cytidin-5′-monophosphat mit NaNO2 in wäßriger Essigsäure wurde geprüft. Die Desaminierungen, die quantitativ zu Uracil, Uridin bzw. Uridin-5′-monophosphat führen sollten, zeigen unter den von uns verwandten Reaktionsbedingungen einen komplexeren Verlauf als erwartet. Nur bei der Desaminierung von Cytidin wurde quantitativ Uridin erhalten. Die Bestimmung der Reaktionsgeschwindigkeitskonstanten der Desaminierungen ergab, daß die Geschwindigkeit der Desaminierung durch den Substituenten am N-1-Atom beeinflußt wird.
    Notes: Summary Attempts were undertaken to determine cytosine/uracil and cytidine/uridine mixtures by UV spectroscopic multicomponent analysis and to investigate the deamination of cytosine, cytidine and cytidine-5′-monophosphate by NaNO2 in aqueous acetic acid. Under the conditions described the deaminations (which were expected to yield quantitatively uracil, uridine and uridine-5′-monophosphate, respectively), show a complex reaction. Only the deamination of cytidine yields uridine quantitatively. The determination of the rate constants of deaminations shows that the reaction is influenced by the substituents at the N-1-atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01154739
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  • 9
    Electronic Resource
    Electronic Resource
    Stereoselective interaction of drug enantiomers with human serum transferrin in capillary zone electrophoresis (II) (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 282-287 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Chiral separation ; Transferrin ; Drugs ; Surface binding site ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Further studies on chiral resolution of drugs with different chemical structures by capillary zone electrophoresis using iron-free human serum transferrin are described. The substances passed a highly concentrated pseudo-stationary protein zone applied in a coated capillary and the possible chiral separation of the optical isomers was followed. Eighteen drugs with different structures were screened, and the enantiomers of clofedanol, buphenine, acebutolol and chlorphenamine were resolved. Several, but not all drugs, showed longer migration times while passing the protein zone, indicating an interaction with transferrin, although chiral resolution was not observed in all cases. The observations provided further information about the properties of the surface interaction sites of transferrin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190223
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  • 10
    Electronic Resource
    Electronic Resource
    Chiral separation of α-amino acids by ligand-exchange capillary electrophoresis using N-(2-hydroxy-octyl)-L-4-hydroxyproline as a selector (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2109-2112 
    Details
    ISSN: 0173-0835
    Keywords: Chiral separation ; Amino acids ; Chiral selector ; Ligand-exchange capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The direct chiral resolution of underivatized α-amino acids by capillary zone electrophoresis (CZE) based on the principle of ligand exchange is described. An N-(2-hydroxyoctyl)-L-4-hydroxyproline/Cu(II) complex was used as a chiral selector. Besides amino acids containing aromatic residues, the basic amino acid histidine was resolved. Baseline separations were obtained for all amino acids investigated. The influence of selector concentration, electrolyte composition and pH on the resolution was investigated. It was found that there is a correlation between pI of the amino acids and the optimal pH.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191211
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