Magdalena Wawrzyńska

In situ photoexcitation of silver-doped titania nanopowders for activity against bacteria and yeasts

Photocatalytic and in situ microbial activity of the amorphous and annealed states of Ag-doped and un-doped titania were examined. Studies on their structure, morphology, composition, and the photo-absorption characteristics of these materials were performed. These results were correlated with the photocatalytic and microbial activity against methicillin resistant Staphylococcus aureus K324 (MRSA), methicillin susceptible S. aureus ATCC 25923 (MSSA), Escherichia coli PA 170, and yeasts Candida albicans ATCC 90028. The annealed powders containing anatase form of titania exhibited relatively higher photocatalytic activity,corresponding to activity against MRSA,when exposed to UV-A radiation. In comparison, amorphous powders exhibited low photoactivity and showed poor antibacterial performance against MRSA under UV-A exposure. Doping of amorphous titania with Ag resulted in an anti-MRSA effect without exposure to UV radiation. In the Ag-doped crystalline anatase samples, the size of Ag primary nanocrystallites increased, which led to the decrease in the surface concentration of Ag and detriment anti-MRSA activity.

Biocidal effect and durability of nano-TiO2 coated textiles to combat hospital acquired infections

While antimicrobial textiles have received considerable interest and attention from both the scientific community and general consumers, there have been very few studies investigating the durability of such antimicrobial activities. In this study, we describe the modification of the surface of textiles that were modified with commercially available titanium dioxide (TiO2) powder (P25 Aeroxide®, Degussa™) using a sonochemical technique. The antibacterial activity of TiO2 can improve textile quality and effectively reduce the rate of infections acquired in hospitals. Medical garments produced from such fabrics may improve the patients recovery and revolutionize the textile market. This modification imparts biocidal properties to these textiles, which were then optimized to acquire properties of the textile. Samples were washed for 30 cycles at three different temperatures (40 °C, 60 °C and 90 °C) to test the durability of the bonding of the nanoparticles to textiles and the effectiveness was examined with respect to their antimicrobial activity against hospital pathogens: Escherichia coli, MRSA and Candida albicans. Samples surfaces were examined by a Scanning Electron Microscope equipped with Energy Dispersive X-ray Spectroscopy (SEM/EDS) for surface imaging. Atomic Absorption Spectrometry (AAS) was used as a technique to quantify the Ti present on the fabric. The best durability of TiO2 on textiles was best retained after washing at 40 °C. From an environmental point of view, the release of nanomaterial from textiles was acceptable against currently available benchmarks. We have investigated the adhesion of nanoparticles (NPs) to the textile surface. Medical garments, bed linens and upholstery produced from such fabrics may improve hospital hygiene against antibiotic resistant superbugs and help reduce hospital acquired infections.

Low Frequency Electromagnetic Field Conditioning Protects against I/R Injury and Contractile Dysfunction in the Isolated Rat Heart.

Low frequency electromagnetic field (LF-EMF) decreases the formation of reactive oxygen species, which are key mediators of ischemia/reperfusion (I/R) injury. Therefore, we hypothesized that the LF-EMF protects contractility of hearts subjected to I/R injury. Isolated rat hearts were subjected to 20 min of global no-flow ischemia, followed by 30 min reperfusion, in the presence or absence of LF-EMF. Coronary flow, heart rate, left ventricular developed pressure (LVDP), and rate pressure product (RPP) were determined for evaluation of heart mechanical function. The activity of cardiac matrix metalloproteinase-2 (MMP-2) and the contents of coronary effluent troponin I (TnI) and interleukin-6 (IL-6) were measured as markers of heart injury. LF-EMF prevented decreased RPP in I/R hearts, while having no effect on coronary flow. In addition, hearts subjected to I/R exhibited significantly increased LVDP when subjected to LF-EMF. Although TnI and IL-6 levels were increased in I/R hearts, their levels returned to baseline aerobic levels in I/R hearts subjected to LF-EMF. The reduced activity of MMP-2 in I/R hearts was reversed in hearts subjected to LF-EMF. The data presented here indicate that acute exposure to LF-EMF protects mechanical function of I/R hearts and reduces I/R injury.

Inhibition of MMP-2 expression affects metabolic enzyme expression levels: Proteomic analysis of rat cardiomyocytes

UNLABELLED In this study we examined the effect of inhibition of MMP-2 expression, using siRNA, on the cardiomyocyte proteome. Isolated cardiomyocytes were transfected with MMP-2 siRNA and incubated for 24h. Control cardiomyocytes from the same heart were transfected with scrambled siRNA following the same protocol. Comparison of control cardiomyocyte proteomes with proteomes from MMP-2 suppressed cardiomyocytes revealed 13 protein spots of interest (9 protein spots increased; 4 decreased). Seven protein spots were identified as mitochondrial enzymes involved in energy production and represent: ATP synthase beta subunit, dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex, cytochrome c oxidase subunit 5A, electron transfer flavoprotein subunit beta, NADH dehydrogenase (ubiquinone) 1 alpha subcomplex subunit 5 and a fragment of mitochondrial precursor of long-chain specific acyl-CoA dehydrogenase. Furthermore, precursor of heat shock protein 60 and Cu-Zn superoxide dismutase were identified. Two protein spots corresponding to MLC1 were also detected. In addition, ATP synthase activity was measured and was increased by approximately 30%. Together, these results indicate that MMP-2 inhibition represents a novel cardioprotective therapy by promoting alterations in the levels of mitochondrial enzymes for improved energy metabolism and by preventing degradation of contractile proteins needed for normal excitation-contraction coupling. BIOLOGICAL SIGNIFICANCE During ischemia and reperfusion of cardiomyocytes, abnormality in excitation-contraction coupling and decreased energy metabolism often lead to myocardial infarction, but the cellular mechanisms are not fully elucidated. We show for the first time that intracellular inhibition of MMP-2 in cardiomyocytes increases contractility of aerobically perfused myocytes, which was accompanied by increased expression of contractile proteins (e.g., MLC-1). We also showed that MMP-2 inhibition produced a cardiomyocyte proteome that is consistent with improved mitochondrial energy metabolism (e.g., increased expression and activity of mitochondrial beta ATP synthase). Thus, MMP-2 appears to be involved in homeostatic regulation of protein turnover. Our results are significant since they point to targeting MMP-2 activity as a novel therapeutic option to limit myocardial damage by decreasing proteolytic degradation of mitochondrial metabolic enzymes and myocardial contractile proteins during ischemia. In addition, the development of novel pharmacological agents that selectively targets cardiac MMP-2 represents a novel approach to treat and prevent other heart diseases.

In vitro human atherosclerotic plaque recognition by photosensitizer mono-L-aspartyl chlorin e6 assisted light induced fluorescence (PALIF)

The main aim of the presented experiments was to assess in vitro capabilities of Photosensitizer Assisted Light Induced Fluorescence (PALIF) to recognise different stages of atherosclerosis. Mono-L-asparyl-chlorin e-6 was used as a photosensitising agent and ultraviolet light (440 nm) as an excitation source to obtain spectra map of artery wall. The luminescence spectra were collected and analised. The specimans were histologically examined and classified into three groups: normal artery wall, atherosclerotic noncalcified plaque and calcified plaque. The ratio of green fluorescence (coming from collagen) to red fluorescence (coming from chlorin e6 bonded with lipid reach, noncalcified tissue) gies a chance to distinguish between normal artery or calcified plaque and noncalcified, lipid reach plaque. Further trials must be performed to evaluate in vitro athermoa detection algorithm as a feedback system for photoangioplasty.

In vitro experimental photodynamic diagnosis of artery atherosclerosis

Background: Although there are several methods for atherosclerosis detection available, none of them seems to be accurate enough to identify the vulnerable atheroscleroitc plaque. Photodynamic diagnosis (PDD) and therapy (PDT) -- a new method evaluated for neoplasms treatment is a modern approach to detecting and treating atherosclerosis. Aim: The purpose of this study was to assess in vitro the capability of PDD with use of chlorin e6 to recognize atherosclerotic plaque and its usefulness as a feedback system for photoangioplasty treatment. Methods: 30 specimens of human aorta. The samples were soaked with chlorin e6 and then washed out. The luminescence spectra were then collected. All samples were examined with light microscopy. Results: Tissue fluorescence is seen as green light. We noted a very strong red fluorescence of chlorin e6 originating from lipid reach plaque. We established a quantitative factor which would be the ratio R of chlorin e6 red intensity in its 660 nm maximum compared to the area of green luminescence centered at 515 nm. The highest value of the ratio was reached at atheromatous samples, then calcified and normal ones R2 = 3.51 ± 0.62, R3 = 1.63 ± 0.31, R1 = 1.51 ± 0.15 respectively. Statistically significant difference was noted between group two and one and between group two and three R2 = 3.51 ± 0.62 vs R3 = 1.63 ± 0.31 (p < 0,05); R2 = 3.51 ± 0.62 vs. R1 = 1.51 ± 0.15 (p<0.05) respectively. Conclusions: the following in vitro study confirms that photosensitizer chlorin e6 accumulates within atheromatous plaque. It may be a specific tool for atheromatous and normal or calcified segments discrimination. The advantage of the above method is a possibility of a real time imaging followed by targeted therapy of various forms and stages of atherosclerosis.