EFFECT OF SOLID DISPERSIONS ON THE SOLUBILITY OF METRONIDAZOLE

The aim of the work is to study the effect of solid dispersions using polyethylene glycols of various molecular weights on the solubility of metronidazole in water. Metronidazole is an antimicrobial and antiprotozoal drug. Its low solubility in water limits the use of metronidazole, causing technological difficulties and reducing its bioavailability. The solubility and release of the active substance from dosage forms can be increased using the solid dispersion methods. Solid dispersions are bi- or multicomponent systems consisting of an active substance and a carrier (a highly dispersed solid phase of the active substance or molecular-dispersed solid solutions) with a partial formation of complexes of variable compositions with the carrier material.

Materials and methods. The substance of metronidazole used in the experiment, was manufactured by Hubei Hongyuan Pharmaceutical Technology Co., Ltd. (China). To obtain solid dispersions, polyethylene glycols of various molar masses – 1500, 2000 and 3000 g/mol – were used. The solid dispersions were prepared by “the solvent removal method”: metronidazole and the polymer were dissolved in a minimum volume of 96% ethyl alcohol (puriss. p.a./analytical grade) at 65±2°C, and then the solvent was evaporated under vacuum to the constant weight. A vacuum pump and a water bath were used at the temperature of 40±2°C. The dissolution of the samples was studied using a magnetic stirrer with heating, and a thermostatting device. The concentration of metronidazole was determined on a spectrophotometer using quartz cuvettes at the wavelength of 318±2 nm. To filter the solutions, syringe nozzles were used, the pores were 0.45 μm, the filter was nylon. Microcrystalloscopy was performed using a microscope with a digital camera. The optical properties of the solutions were investigated using a quartz cuvette and a mirror camera (the image exposure – 20 sec).

Results. Obtaining solid dispersions increases the completeness and rate of the metronidazole dissolution. The solubility of metronidazole from solid dispersions increases by 14–17% in comparison with the original substance. The complex of physical-chemical methods of the analysis, including UV spectrophotometry, microcrystalloscopy and the study of the optical properties of the obtained solutions, makes it possible to suggest the following. The increase in the solubility of metronidazole from solid dispersions is explained by the loss of crystallinity and the formation of a solid solution of the active substance and the solubilizing effect of the polymer with the formation of colloidal solutions of metronidazole at subsequent dissolution of the solid dispersion in water.

Conclusion. The preparation of solid dispersions with polyethylene glycols improves the dissolution of metronidazole in water. The results obtained are planned to be used in the development of rapidly dissolving solid dosage forms of metronidazole with an accelerated release and an increased bioavailability.

Interaction of NK Cells, Trophoblast, and Endothelial Cells during Angiogenesis

We studied changes in angiogenesis during contact interaction of natural killer cells and endothelial cells in the presence of secretory products of trophoblast cells activated by various cytokines. Activated trophoblast regulates angiogenesis by producing soluble factors that affect endothelial cells either directly or indirectly through activation of proangiogenic activity of natural killer cells. A stimulating effect of the trophoblast supernatants activated by IL-1β and an inhibitory effect of trophoblast supernatants activated by IL-6 and TGFβ for the formation of tube-like structures by endothelial cells were revealed. During contact culturing, natural killer cells increased the length of tube-like structures formed by endothelial cells. The trophoblast activated by IL-1β affects angiogenesis both directly through the production of proangiogenic factors and indirectly through activation of the proangiogenic potential of natural killer cells. Trophoblast activated by IFNγ affects angiogenesis only by stimulating the proangiogenic potential of natural killer cells. Under conditions of contact interaction of natural killer cells and endothelial cells, soluble factors of trophoblast activated by IL-6 or TGFβ attenuated the angiogenesis-stimulating effect of natural killer cells.

Effect of Factors Secreted by the Placenta on Phenotype of THP-1 Cells Cultured on a 3D Scaffold

We studied the effects of secretory products of the placenta obtained from women with normal pregnancy and preeclampsia on the expression of surface markers by THP-1 cells cultured on a 3D Matrigel scaffold. Secretory products of third trimester placentas obtained from women with normal pregnancy reduced the relative number of THP-1 cells expressing CD54 and CD14 molecules and expression of CD14 and CD95 molecules by THP-1 cells in comparison with the effect of secretory products first trimester placentas. In parallel, the intensity of CD49d expression by THP-1 cells increased in the presence of secretory products of third trimester placentas in comparison with the first trimester. No differences in the expression of the studied molecules by THP-1 cells under the effect of placentas from women with physiological pregnancy and patients with preeclampsia were found.

Effect of placenta secretory products on migration activity of endothelial EA.Hy926 cells

We studied the influence of factors secreted by the placenta in physiological and preeclampsia-complicated pregnancy on migration activity of endothelial EA.Hy926 cells. It was found that migration of endothelial cells was more intensive in the presence of secretory factors from trimester I placentas in comparison with trimester III placentas and was lower in the presence of placental factors in preeclampsia in comparison with physiological pregnancy.

CELLS OF IMMUNE SYSTEM OF MOTHER АND TROPHOBLAST CELLS: CONSTRUCTIVE COOPERATION FOR THE SAKE OF ACHIEVEMENT OF THE JOINT PURPOSE

In the present review modern data about change of morfo-functional properties of a trophoblast during pregnancy, and also about influence of the cytokines produced by cells of a microenvironment, including leucocytes of mother, on a functional state of trophoblast is cited. Features of interaction between trophoblast and immune cells of mother are described within physiological pregnancy and within pregnancy complicated by preeclampsia. 

[Cells of immune system of mother and trophoblast cells: constructive cooperation for the sake of achievement of the joint purpose]

In the present review modern data about change of morfo-functional properties of a trophoblast during pregnancy, and also about influence of the cytokines produced by cells of a microenvironment, including leucocytes of mother, on a functional state of trophoblast is cited. Features of interaction between trophoblast and immune cells of mother are described within physiological pregnancy and within pregnancy complicated by preeclampsia.

Gene expression for VEGF-A, VEGF-C, and their receptors in murine lymphocytes and macrophages

Vascular endothelial growth factors VEGF-A and VEGF-C are the main angiogenic factors that control growth of new blood and lymphatic vessels in the organism, and they also possess several immunoregulatory activities. Expression of VEGF-A and VEGF-C mRNA as well as mRNA for VEGF receptors in lymphocytes and macrophages of naive mice was investigated. Using reverse transcription and subsequent polymerase chain reaction, we found that peritoneal macrophages, thymocytes, and lymph node cells constitutively expressed VEGF-A and VEGF-C mRNA. In addition, macrophages were positive for VEGFR-1, VEGFR-2, VEGFR-3, NRP-1, and NRP-2 mRNA, whereas thymocytes and lymph node cells expressed mRNA of the same receptors except VEGFR-1. These data expand our knowledge concerning gene distribution of VEGF receptors in the organism, in particular, among the cells of the immune system. This suggests that, along with their major angiogenic properties, VEGF family members additionally might also perform important mediatory functions within the immune system.