Simultaneous determination of 6,7-dimethylesculetin and geniposide in rat plasma and its application to pharmacokinetic studies of Yin Chen Hao Tang preparation

A method for the rapid and simultaneous determination of 6,7-dimethylesculetin (CAS 120-08-1) and geniposide (CAS 24512-63-8) in rat plasma has been developed, using validated high performance liquid chromatography (HPLC) with solid phase extraction (SPE). The HPLC analysis was performed on a commercially available column (200 mm x 4.6 mm, 5 microm) with acetonitrile-methanol-0.1% aqueous formic acid as mobile phase and the UV detection at 343 nm and 238 nm for 6,7-dimethylesculetin and geniposide, respectively. The calibration curves for 6,7-dimethylesculetin and geniposide were linear over the range 0.4-25.6 microg/mL and 1.12-71.68 microg/mL, respectively. The lower limits of quantitation were 0.40 microg/ mL and 1.12 microg/mL, and the lower limits of detection were 0.06 microg/mL and 0.09 microg/ mL, respectively. The intra-day and inter-day precision for 6,7-dimethylesculetin and geniposide were < 5%, whereas the absolute recovery percentages were > 74%. A successful application of the developed HPLC analysis was demonstrated for the pharmacokinetic study of a Traditional Chinese Medicine formula of Yin Chen Hao Tang preparation.

Pharmacokinetics of cimifugin in rat plasma after oral administration of the extract of Saposhnikovia divaricatae root : Determination of cimifugin by high performance liquid chromatography coupled with solid phase extraction

High performance liquid chromatography (HPLC) coupled with the solid phase extraction method was developed for determining cimifugin (a coumarin derivative; one of Saposhnikovia divaricatae's constituents) in rat plasma after oral administration of Saposhnikovia divaricatae extract (SDE), and the pharmacokinetics of cimifugin either in SDE or as a single compound was investigated. The HPLC analysis was performed on a commercially available column (4.6 mm x 200 mm, 5 pm) with the isocratic elution of solvent A (Methanol) and solvent B (Water) (A:B=60:40) and the detection wavelength was set at 250 nm. The calibration curve was linear over the range of 0.100-10.040 microg/mL. The limit of detection was 30 ng/mL. At the rat plasma concentrations of 0.402, 4.016, 10.040 microg/mL, the intra-day precision was 6.21%, 3.98%, and 2.23%; the inter-day precision was 7.59%, 4.26%, and 2.09%, respectively. The absolute recovery was 76.58%, 76.61%, and 77.67%, respectively. When the dosage of SDE was equal to the pure compound calculated by the amount of cimifugin, it was found to have two maximum peaks while the pure compound only showed one peak in the plasma concentration-time curve. The pharmacokinetic characteristics of SDE showed the superiority of the extract and the properties of traditional Chinese medicine.

Twitter-archive und die Herausforderungen von "Big Social Data" für die Medien- und Kommunikationswissenschaft

Twitter ist eine besonders nützliche Quelle für Social-Media-Daten: mit dem Twitter-API (dem Application Programming Interface, das einen strukturierten Zugang zu Kommunikationsdaten in standardisierten Formaten bietet) ist es Forschern möglich, mit ein wenig Mühe und ausreichenden technische Ressourcen sehr große Archive öffentlich verbreiteter Tweets zu bestimmten Themen, Interessenbereichen, oder Veranstaltungen aufzubauen. Grundsätzlich liefert das API sehr langen Listen von Hunderten, Tausenden oder Millionen von Tweets und den Metadaten zu diesen Tweets; diese Daten können dann auf verschiedentlichste Weise extrahiert, kombiniert, und visualisiert werden, um die Dynamik der Social-Media-Kommunikation zu verstehen. Diese Forschung ist häufig um althergebrachte Fragestellungen herum aufgebaut, wird aber in der Regel in einem bislang unbekannt großen Maßstab durchgeführt. Die Projekte von Medien- und Kommunikationswissenschaftlern wie Papacharissi und de Fatima Oliveira (2012), Wood und Baughman (2012) oder Lotan et al. (2011) – um nur eine Handvoll der letzten Beispiele zu nennen – sind grundlegend auf Twitterdatensätze aufgebaut, die jetzt routinemäßig Millionen von Tweets und zugehörigen Metadaten umfassen, erfaßt nach einer Vielzahl von Kriterien. Was allen diesen Fällen gemein ist, ist jedoch die Notwendigkeit, neue methodische Wege in der Verarbeitung und Analyse derart großer Datensätze zur medienvermittelten sozialen Interaktion zu gehen.

Die Auswirkungen von Neid auf individuelle Leistungen: Ergebnisse einer Panelanalyse

Relative Einkommensunterschiede lösen innerhalb einer Referenzgruppe oftmals Neid aus und beeinflussen damit die individuelle Leistungsbereitschaft. In der ökonomischen Forschung ist bislang dieser Zusammenhang wenig untersucht worden. Unser Beitrag analysiert den Einfluss von relativen Einkommensunterschieden auf die Leistung von Fußballprofis der deutschen Bundesliga. Insgesamt werden 1040 Spieler über einen Zeitraum von 8 Spielzeiten zwischen 1995 und 2004 untersucht. Relative Einkommensunterschiede zwischen Mannschaftskollegen erweisen sich als entscheidender Einfluss auf die individuelle Leistung der Spieler. Eine Verschlechterung in der relativen Einkommensposition vermindert ceteris paribus die individuelle Leistungsbereitschaft. Eine höhere Einkommensungleichheit verstärkt solche positionsbedingten Externalitäten. Relative income differences are likely to lead to envy within a reference group. Envy in turn influences social behavior and individual performance. While positional concerns are apparent in daily life, empirical evidence is rare in the economic literature. This paper investigates the impact of the relative income position on individuals’ performance or productivity. As „performance“ is difficult to measure we turn to soccer players whose performance has been well documented. The broad sample covers eight seasons of the German premier soccer league (Bundesliga) between 1995 and 2004, and includes 1040 players, a salary proxy and several performance variables. The results show that player performance is strongly affected by relative income position. A disadvantage in the relative income position reduces productivity. The larger the income differences within a team, the stronger are the effects of positional concern. Team composition also significantly affects behaviour.

Study of the novel non-xanthine heterocyclic compound GU 285 as a potent non-selective adenosine receptor antagonist in the rat

The novel pyrazolo[3,4-d]pyrimidine compound GU285 (4-amino-6-alpha-carbamoylethylthio-1- phenylpyrazolo[3,4-d]pyrimidine, CAS 134896-40-5) was examined for its ability (1) to inhibit binding of adenosine (ADO) receptor ligands in rat brain membranes, (2) to antagonise functional responses to ADO agonists in rat right and left atria and coronary resistance vessels, and (3) to reduce the fall in heart rate and arterial blood pressure produced by the ADO A1 agonist N6-cyclopentyladenosine (CPA) in the intact, anaesthetized rat. GU285 competitively inhibited binding of the ADO A1 agonist [3H]-R-N6-phenylisopropyladenosine (R-PIA) yielding a Ki value of 11 (7-18) nmol.l-1 (geometric mean +/- 95% Cl). When assayed against the ADO A2A selective agonist [3H]-2-[p-(2-carboxyethyl)- phenethylamino]-5'-N-ethylcarboxamidoadenosine, (CGS21680), a Ki of 15 (10-24) nmol.l-1 was obtained. In spontaneously beating right atria, GU285 competitively antagonized negative chronotropic effects of R-PIA with a pA2 of 8.7 +/- 0.3 and in electrically paced left atria, GU285 competitively antagonized negative inotropic effects of R-PIA with a pA2 of 9.0 +/- 0.1. In the potassium-arrested, perfused rat heart GU285 (1 mumol.l-1) antagonized only the high sensitivity, ADO A2B mediated component of the biphasic relaxation of the coronary vasculature produced by NECA. The low sensitivity component was unchanged. GU285 (1 mumol.kg-1) antagonized the negative chronotropic and hypotensive effects of the adenosine A1 agonist CPA in anaesthetized rats, producing a 10-fold rightward shift in the dose-response relationship. These data demonstrate that in the rat, GU285 is a potent, non-selective adenosine receptor antagonist that maintains its activity in vivo.