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PubMed1992

In vitro and in situ absorption of etamsylate. Part 2: In vitro and in situ properties.

The oil to water partition behaviour, the diffusion across artificial lipid barriers and the in situ gastro-intestinal absorption of the haemostatic etamsylate were studied. Very small partition coefficients were obtained (0.015-0.13) which are independent on the pH (range 1 to 6) and the nature of the organic phase (n-hexane, n-octanol, ethylacetate). Using the Sartorius membrane stimulator small diffusion constants were calculated both at phase I pH 6.0 (kd = 7.82.10(-3)cm.min-1) and especially at phase I pH 1.2 (kd = 4.7.10(-6) cm x min-1). The in situ absorption experiments on male Wistar rats showed very poor gastric absorption, but considerable intestinal absorption rate (absorption rate constant ka = 0.39 +/- 0.19 h-1, absorption half life t1/2(ka) = 1.94 +/- 0.60 h). The ion-pair diffusion across the intestinal wall seems to be the main reason responsible for the fast intestinal absorption. The obtained results are consistent to the literature data concerning etamsylate pharmacokinetics in vivo.

Animals↗
PubMed1990

[In vitro and in vivo effect of thyroid hormones on the growth of neuroblastoma cells. I. The effect of triiodothyronine in vitro].

The effect of triiodothyronine (T3) on the differentiation of cultured neuroblastoma (NB) cells was studied after 9 days of treatment with a dose of 10(-4) M/10(6) cells per day. Using phase contrast microscopy, 30-50% of NB cells showed formation of neurites as a morphological sign of cellular differentiation. The initial rise of the mitosis rate was followed by a plateau. Changes in cyclic nucleotide content, in the triphosphates and in the activity of the enzyme ornithine decarboxylase (ODC) were assessed in 2 human and 2 murine cell lines to serve as biochemical parameters of the cell differentiation induced by T3. Whereas the cAMP level increased significantly (3 to 7 fold compared with its initial value), the cGMP value dropped to 30 to 50% of that of the control group. ATP and GTP increased about 200%, the ODC showed a decrease of about 50%. The present studies show a biphasic effect of T3 on neuroblastoma cells: the initial rise of mitotic activity is followed by increased cell differentiation starting from day 4 of the treatment.

Adenosine Triphosphate↗