Activated platelets are key components in many arterial disorders. P-selectin is an activation-dependent platelet receptor, which is also identified in endothelial cells. Together with E- and L-selectin it constitutes the selectin family. These transmembrane proteins have continued to attract great interest as they support rapid and reversible cell adhesion in flow systems and thus play an essential role in multicellular interactions during thrombosis and inflammation. Similarly to other lectins, selectins bind to different glycoconjugates with varying affinities. Protein ligands, equipped with the appropriate carbohydrate and sulfate moieties for P-selectin binding, have been identified in normal peripheral blood leukocytes and several non-hematopoietic organs, as well as on cancer cells. For diagnostic purposes, P-selectin can readily be detected on the platelet surface by flow cytometry and by ELISA as a soluble ligand in the plasma. Along with other markers, these data can be used in the assessment of platelet activation status. Such results bear clinical significance since P-selectin has been implicated in the pathogenesis of wide-spread disorders including coronary artery disease, stroke, diabetes and malignancy.

Osmotic gradient ektacytometry (measuring elongation index in the function of osmolality at a constant shear stress) is a sensitive method to analyze red blood cell (RBC) deformability and investigating the optimal osmolality range for the cells in normal or pathophysiological cellular and micro-environmental conditions. However, the methodological conditions are different, since the results are infl uenced by the applied shear stress (SS). In this study we investigated rat, dog, pig and human blood samples at SS of 1, 2, 3, 5, 10, 20 and 30 Pa. To describe the range being related to the cell deformability, we introduced new calculated parameters obtained from the raw data of the elongation index (EI)-osmolality (O) curves. Our results showed that: (1) Osmoscan data tested at 20 or 30 Pa do not differ signifi cantly from each other; (2) Under SS of 20 Pa the EImax, the O (EImax), the EI min and the area under curve nearly linearly decrease in the function of SS with different slope in rat, dog, pig and human blood; (3) Measurements under 3 Pa SS become unstable; (4) The differences between minimal and maximal EI and the belonging osmolality values, and their ratios, as new calculated parameters ( Δ EI, Δ O, Δ EI/ Δ O, EImax/EImin and O (EImax)/Omin) can be suitable for further analysis of the osmoscan curves together with other hemorheological parameters describing RBC deformability; and (5) Decreased erythrocyte deformability (by rigidifying with glutaraldehyde) can be refl ected well with the following, calculated osmoscan parameters: Δ O, rO, rEI/rO and Δ EI/ Δ O.

The small antifungal protein secreted by Penicillium chrysogenum (PAF) inhibits the growth of important zoo pathogenic filamentous fungi, including members of the Aspergillus family.It was shown previously that PAF has no toxic effects on mammalian cells in vitro. We carried out safety experiments by investigating the in vivo effects of PAF by inoculating adult C57/B16 mice with PAF intranasally. Animals were randomly divided into six groups and subjected to different PAF concentrations, up to 54 µg, either once a week for up to 8 weeks or once every day for two weeks. Animals neither died due to the treatment nor were any side effects observed. Histological examinations did not find any pathological reaction in the liver, in the mucous membrane of the nose, and in the lungs, even in the highest concentration used.Mass spectrometry revealed that ZZZ. The effect of the drug on the skin was examined in an irritative dermatitis model by measuring the thickness of the ears. This proved to be the same following PAF application as in control (23.8±9.2 vs. 22.5±5.0 µm, respectively) and significantly less than when treated with phorbol-12-myristate-13-acetate (PMA; 57.5±29.2 µm) used as positive control. Histological changes relative to control were present only in the case of PMA. Positron emission tomography was used to follow potential inflammation of the lungs. Neither the application of control saline nor that of PAF induced any inflammation while the positive control lipopolysaccharide did. Since no toxic effects of PAF were found either in intranasal application or in local external treatment, our result is the first step for introducing PAF as potential antifungal drug in human therapy.

PAF, a small antifungal protein from Penicillium chrysogenum, inhibits the growth of several pathogenic filamentous fungi, including members of the Aspergillus genus. PAF has been proven to have no toxic effects in vivo in mice by intranasal application. To test its efficacy against invasive pulmonary aspergillosis (IPA), experiments were carried out in mice suffering from IPA. Adult mice were immunosuppressed and then infected with Aspergillus fumigatus. After stable infection, the animals were inoculated with PAF intranasally at a concentration of 2.7 mg/kg twice per day. At this concentration—which is highly toxic in vitro to A. fumigatus—the mortality of the animals was slightly delayed but finally all animals died. Histological examinations revealed massive fungal infections in the lungs of both PAF-treated and untreated animal groups. Because intranasally administered PAF was unable to overcome IPA, modified and combined therapies were introduced. The intraperitoneal application of PAF in animals with IPA prolonged the survival of the animals only 1 day. Similar results were obtained with amphotericin B (AMB), with PAF and AMB being equally effective. Combined therapy with AMB and PAF—which are synergistic in vitro—was found to be more effective than either AMB or PAF treatment alone. As no toxic effects of PAF in mammals have been described thus far, and, moreover, there are so far no A. fumigatus strains with reported inherent or acquired PAF resistance, it is worth carrying out further studies to introduce PAF as a potential antifungal drug in human therapy.

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Cellular interactions among platelets, leukocytes and endothelial cells are considered as a major cause of inflammation and atherosclerosis in many diseases. Via exposed surface receptors and released soluble substances, activated platelets play a crucial role in the initiation of inflammatory processes, resulting in endothelial injury and leading to formation of atherosclerotic plaque with possible thrombotic complications. Classic anti-platelet treatments (e.g. cyclooxygenase inhibitor or ADP-receptor antagonist) have favorable effects in patients with vascular diseases, but they also have several limitations such as increased bleeding risk or non-responsiveness. Thus, the need and opportunities for developing novel therapeutic inhibitors for platelet-mediated events are obvious. Animal and (pre)clinical human studies have suggested that some recently produced specific antagonists of P-selectin from α-granules, as well as its main ligand/receptor P-selectin Glycoprotein Ligand-1, the two major platelet chemokines CXCL4 and CCL5, as well as CD40L, may be considered potential new candidates in the treatment of atherogenesis and inflammation. In this review, we summarize the pathophysiological roles of these effectors in platelet activation and acute or chronic inflammation, and discuss the latest findings on promising antagonistic agents in basic and clinical studies in the prevention of platelet-mediated cellular interactions.

Abstract. Laboratory investigations often require centrifugation of blood samples for various erythrocyte tests. Although there 8 is a lack of data about the effect of centrifugation at various g force levels on erythrocyte rheological properties. We aimed 9 to investigate the effect of a 10-minute centrifugation at 500, 1000 or 1500 g at 15• C of rat, dog, pig and human venous 10 (K3-EDTA, 1.5 mg/ml) blood samples. Hematological parameters, erythrocyte deformability, cell membrane stability, osmotic 11 gradient ektacytometry (osmoscan) and erythrocyte aggregation were determined. Hematological and erythrocyte deformability 12 parameters showed interspecies differences, centrifugation caused no significant alterations. Cell membrane stability for human other hand, erythrocyte deformability parameters were stable, cell membrane stability and osmoscan data show minor shifts.

Growing number of clinical and experimental data reflect to the gender differences of hemorheological parameters. However, little is known about the potential hemorheological effect of gonadectomy and consequent changes in sex hormone concentration. Adult, sameaged male and female rats were involved in the study. In control male and female group no surgical intervention was performed. In gonadectomized (GoE) male and female groups bilateral orchidectomy or ovariectomy were completed. Body weight measurement and blood sampling were carried out in the 1 st , 2 nd and 3 rd postoperative months. The GoE females had significant bodyweight augmentation and their plasma estrogen concentration decreased by 40-45% by the 1 st postoperative month, while in males the testosterone level was not detectable after gonadectomy. Leukocyte and platelet counts moderately increased in GoE males. Elongation index values of erythrocytes slightly decreased in both genders after gonadectomy, showing converging values. Erythrocyte aggregation index values of GoE females significantly raised by the 2 nd month. It can be concluded that gonadectomy in rats resulted in alteration (dominantly impairment) of blood micro-rheological parameters, by different manner in males and females. Supposedly decrease in estrogen can cause more expressed hemorheological changes than the cessation of testosterone.