State of antioxidant system in urogenital trichomoniasis and membranotropic effect of metronidazole

The objective of this work was to study the activity of glutathione peroxidase, glutathione reductase and the level of sulfhydryl groups in erythrocytes of patients with urogenital trichomoniasis and the effect of metronidazole on the degree of osmotic and peroxide resistance of erythrocytes from healthy donors. We examined 15 patients with urogenital trichomoniasis and 20 healthy volunteers. We studied native preparations, and also carried out a culture method using the Johnson-Trussel nutrient medium (CPLM) to identify Trichomona vaginalis. The activity of glutathione reductase, glutathione peroxidase and the level of total sulfhydryl groups were determined in erythrocytes of peripheral blood. The membrane effect of metronidazole was evaluated in in vitro experiment by the degree of osmotic and peroxide resistance of erythrocytes from healthy people. It has been established that a significant decrease in glutathione reductase and glutathione peroxidase activities in erythrocytes is observed, which indicates a violation of the antioxidant system in this pathology. It was shown in vitro experiment, that metronidazole in low concentration (80 μmol /l) has the ability to inhibit erythrocyte hypotonic hemolysis, and high concentration (250 μmol/l) leads to a decrease in osmotic and peroxide resistance of erythrocytes. Thus, inhibition of the activity of the enzymatic link of the antioxidant defense is observed in urogenital trichomoniasis, which is one of the mechanisms for the development of pathology at the cellular level in this disease. It has been shown that the isolated membranotropic action of metronidazole depends on its concentration – the drug at low concentration is able to inhibit hypotonic hemolysis of erythrocytes, and high concentration makes them more sensitive to the osmotic and peroxide hemolysis. The obtained results should be taken into account in the development of complex methods of therapy for urogenital trichomoniasis.

Biconcave shape of human red-blood-cell ghosts relies on density differences between the rim and dimple of the ghost's plasma membrane

The shape of the human red blood cell is known to be a biconcave disk. It is evident from a variety of theoretical work that known physical properties of the membrane, such as its bending energy and elasticity, can explain the red-blood-cell biconcave shape as well as other shapes that red blood cells assume. But these analyses do not provide information on the underlying molecular causes. This paper describes experiments that attempt to identify some of the underlying determinates of cell shape. To this end, red-blood-cell ghosts were made by hypotonic hemolysis and then reconstituted such that they were smooth spheres in hypo-osmotic solutions and smooth biconcave discs in iso-osmotic solutions. The spherical ghosts were centrifuged onto a coated coverslip upon which they adhered. When the attached spheres were changed to biconcave discs by flushing with an iso-osmotic solution, the ghosts were observed to be mainly oriented in aflatalignment on the coverslip. This was interpreted to mean that, during centrifugation, the spherical ghosts were oriented by a dense band in its equatorial plane, parallel to the centrifugal field. This appears to be evidence that the difference in the densities between the rim and the dimple regions of red blood cells and their ghosts may be responsible for their biconcave shape.