The role of the adenosine triphosphate-sensitive potassium channels in pinacidil-induced vasodilatation of the human saphenous vein in patients with and without type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) increases cardiovascular complications. Diabetic vascular dysfunction is associated with the reduced activity of the different smooth muscle potassium (K+) channels. Thus, the objective of our study was to investigate the role of the adenosine triphosphate (ATP)-sensitive K+ (KATP) channels in the relaxant effect of potassium channel opener, pinacidil on the human saphenous vein (HSV) obtained from the patients with and without T2DM. The rings of HSV without the endothelium, obtained from the patients who had undergone coronary bypass surgery, were mounted in an organ bath system and isometric tension was recorded. The relaxation of HSV, precontracted with phenylephrine, was produced by pinacidil. The expression of KATP subunits (Kir6.1, Kir6.2 and SUR2B) was detected by immunohistochemistry and Western blot. Pinacidil produces comparable effects on HSV in patients with and without T2DM. The suppression of pinacidil effect and its maximal relaxation by glibenclamide, selective blocker of KATP channels, was more pronounced on HSV in patients without T2DM. All three types of KATP subunits are expressed on the smooth muscle cells of HSV. While there are no differences in the expression of Kir6.1 and Kir6.2, the expression of SUR2B is lower in HSV in patients with T2DM. Pinacidil produced comparable KATP-dependent and -independent relaxation of the HSV in patients with/without T2DM. According to the effect of glibenclamide and the applied molecular analysis, presented findings demonstrated that diabetes mellitus was associated with the reduced expression of SUR2B subunit in the vascular smooth muscle of HSV.

Stefin B deficiency reduces tumor growth via sensitization of tumor cells to oxidative stress in a breast cancer model.

Lysosomal cysteine cathepsins contribute to proteolytic events promoting tumor growth and metastasis. Their enzymatic activity, however, is tightly regulated by endogenous inhibitors. To investigate the role of cathepsin inhibitor stefin B (Stfb) in mammary cancer, Stfb null mice were crossed with transgenic polyoma virus middle T oncogene (PyMT) breast cancer mice. We show that ablation of Stfb resulted in reduced size of mammary tumors but did not affect their rate of metastasis. Importantly, decrease in tumor growth was correlated with an increased incidence of dead cell islands detected in tumors of Stfb-deficient mice. Ex vivo analysis of primary PyMT tumor cells revealed no significant effects of ablation of Stfb expression on proliferation, angiogenesis, migration and spontaneous cell death as compared with control cells. However, upon treatment with the lysosomotropic agent Leu-Leu-OMe, cancer cells lacking Stfb exhibited a significantly higher sensitivity to apoptosis. Moreover, Stfb-ablated tumor cells were significantly more prone to cell death under increased oxidative stress. These results indicate an in vivo role for Stfb in protecting cancer cells by promoting their resistance to oxidative stress and to apoptosis induced through the lysosomal pathway.

Antistaphylococcal activity of Inula helenium L. root essential oil: eudesmane sesquiterpene lactones induce cell membrane damage.

The purpose of this study was to investigate the inhibitory/bactericidal activity and cell membrane effects of the hydrodistilled essential oil of Inula helenium L. roots against Staphylococcus aureus. Additionally, detailed chemical investigation was done in order to pinpoint the most active oil constituents and also the parts of these molecules responsible for their antimicrobial effect. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the broth microdilution method. The membrane-active nature of this oil was investigated by measuring the culture turbidity, leakage of phosphates, and 260-nm-absorbing material, together with lysis of the exposed cells. Finally, the effect of the oil on the cells was visualized using scanning electron microscopy (SEM). The chemical composition of the essential oil was analyzed using gas chromatography-mass spectrometry (GC-MS) and preparative medium-pressure liquid chromatography (MPLC). Chemical modification of the oil was performed using catalytic hydrogenation (H(2), Pd/C) and reduction with NaBH(4). The MIC and MBC values were 0.01 µl mL(-1) and 0.02 µl mL(-1), respectively. Membrane damage was demonstrated through increased permeability (phosphates and nucleic acid leakage), followed by lysis of the exposed cells, captured on SEM images. The most active constituents were alantolactone, isoalantolactone, and diplophyllin. The essential oil showed very potent antistaphylococcal activity, with obvious membrane-damaging effects. Sesquiterpene lactones were found to be the most active principles of the oil, whose eudesmane core olefinic bonds, along with the α,ß-methylene-lactone ring, are essential structural parts responsible for the exhibited antimicrobial activity.