Differential regulatory effect of progesterone on the proliferation and apoptosis of uterine leiomyoma tissue explants and primary leiomyoma cell cultures.

OBJECTIVE: The growth of uterine leiomyomas is regulated by progesterone, although the underlying molecular mechanisms are not fully understood. METHODS: Primary leiomyoma cells were isolated by standard method from 16 samples of uterine leiomyoma tissue. Uterine leiomyoma explants and primary leiomyoma cell cultures were exposed to progesterone in concentrations of 0.01 µg/ml, 0.1 µg/ml and 1 µg/ml for 24 h. Cell apoptosis was assessed with Annexin V assays performed in cell cultures by flow cytometry. The expression of PR-A, PR-B, Ki67, Akt, ERK, PTEN and PPARγ mRNAs was estimated in cultured leiomyoma cells and tissue explants by real time RT-PCR. RESULTS: Treatment with progesterone promoted viability and proliferation of cultured leiomyoma cells in a dose-dependent manner. Low and high doses of progesterone decreased early apoptosis of leiomyoma cells. High concentrations of progesterone increased the number of living cells in Annexin V assays. High doses of progesterone increased the expression of Ki67 mRNA, while low doses increased the expression of PR-A mRNA in cultured leiomyoma cells and tissue explants. In cell cultures, low doses of progesterone increased the expression of PR-B mRNA and the expression of PTEN and PPARγ mRNAs in a dose-dependent manner. Exposure of leiomyoma tissue explants to progesterone led to increased expression of PR-B and ERK mRNAs in a dose-dependent manner. CONCLUSIONS: The effects of progesterone on the apoptosis and proliferation of leiomyoma cells was dose-dependent and different in cell cultures and leiomyoma explants, possibly as a result of impacts derived from the tumor microenvironment.

Evidence of entropically driven C60 fullerene aggregation in aqueous solution.

In the present work, we report the first experimental evidence of entropically driven C60 fullerene aggregation in aqueous solution, occurring with nearly zero enthalpy change.

Spectroscopic study of proflavine adsorption on the carbon nanotube surface.

Despite the fact that non-covalent interactions between various aromatic compounds and carbon nanotubes are being extensively investigated now, there is still a lack of understanding about the nature of such interactions. The present paper sheds light on one of the possible mechanisms of interaction between the typical aromatic dye proflavine and the carbon nanotube surface, namely, π-stacking between aromatic rings of these compounds. To investigate such a complexation, a qualitative analysis was performed by means of ultraviolet visible, infrared, and nuclear magnetic resonance spectroscopy. The data obtained suggest that π-stacking brings the major contribution to the stabilization of the complex between proflavine and the carbon nanotube.

C60 fullerene aggregation in aqueous solution.

In the present work we develop a novel approach for quantification of the energetics of C60 fullerene aggregation in aqueous media in terms of equilibrium aggregation constant KF. In particular, it is shown that the experimental determination of the magnitude of KF is possible only within the framework of the 'up-scaled aggregation model', considering the C60 fullerene water solution as a solution of fullerene clusters. Using dynamic light scattering (DLS) data we report the value, K(F) = 56,000 M(-1), which is in good agreement with existing theoretical estimates and the results of energetic analyses. It is suggested that the proposed 'up-scaled model' may be used in any instances of non-specific aggregation resulting in formation of large spherical particles. The measurement of the translational diffusion coefficient and the dimensions of the light scattering particles using a DLS approach with respect to C60 fullerene aggregates is found to contain significant systematic errors originating from the interaction effect that is well-known for micellar solutions. As a result, corrections to the equations associated with DLS data are proposed.

Complexation of C60 fullerene with aromatic drugs.

The contributions of various physical factors to the energetics of complexation of aromatic drug molecules with C(60) fullerene are investigated in terms of the calculated magnitudes of equilibrium complexation constants and the components of the net Gibbs free energy. Models of complexation are developed taking into account the polydisperse nature of fullerene solutions in terms of the continuous or discrete (fractal) aggregation of C(60) molecules. Analysis of the energetics has shown that stabilization of the ligand-fullerene complexes in aqueous solution is mainly determined by intermolecular van der Waals interactions and, to lesser extent, by hydrophobic interactions. The results provide a physicochemical basis for a potentially new biotechnological application of fullerenes as modulators of biological activity of aromatic drugs.