With the technical assistance of Z. Blaxek, M. R6bl, and E. Sladkova and the statistical evaluation of Z. Roth

Abstract-The feasibilities of the Kelvin probe mode were shown to estimate a surface potential of lympho cytes from the patients with leukemia. Having compared the values of the surface potential obtained by the traditional method of microelectrophoresis and by the Kelvin probe mode, it was established that the use of the atomic force microscope made it possible to obtain data which were of specified diagnostic importance while studying lymphocyte functional status at different stages in leucopoiesis and indicated progression of the pathological process.

With the technical assistance of 1. Blaiek, M. Rabl and E. Sladkova and the statistical evaluation of Ing. 1. Roth MethodsThe present experiments were performed under pentobarbital anaesthesia (20 to 40 mgAg body \vt iv) on mongrel dogs, weighing from 20 to 25 kg. The electronic device for synchronizing the condenser discharge with selected phases of the electrocardiogram has been described previously. 1 The methods, in general, were also the same as before except that an inductive resistance (inductance 0.29 henry and resistance 27

Cardiac troponin T determination plays a dominant role in diagnosis of myocardial pathologies. Despite generally accepted use of high-sensitive cardiac troponin T assays (hscTnT) and clearly defined cut-off limit in adults, the uncertainty persists in infants. The aim of this study was to assess plasmatic concentrations of hscTnT and describe sequential age-related dynamic changes of hscTnT in healthy infants and toddlers. Seventy-eight children (52 males/26 females) from Czech Republic aged 44 to 872 days (median, interquartile range 271; 126 to 486 days) were consecutively enrolled in the single-center, prospective observational study. Plasma concentrations of hscTnT were analyzed by the electrochemiluminescent method, age-related reference intervals were calculated using the polynominal regression model. Amongst the study population (n=78), the upper limit of hscTnT concentration defined as the 99th percentile was calculated. The 99th percentile with 95 % confidence interval at the end of 2nd, 3rd, 4th, 5th, 6th and 7th month of postnatal life were: 81 (40.6 to 63.6), 61 (36.0 to 55.3), 47 (31.9 to 48.3), 37 (28.1 to 42.3), 30 (24.7 to 37.2) and 25 (21.5 to 32.7) ng/l, respectively. Concentration of adults 99th percentile (14 ng/l) was achieved approximately at 1 year of postnatal life. Statistically significant negative correlation of hscTnT concentration with age (r=-0.81, p<0.001) was found. Significant gender differences were not found (p>0.07). The study revealed substantially increased reference intervals of hscTnT levels in infants when compared with adult population. Based on our preliminary results, the age-related interpretation of hscTnT plasmatic concentration is recommended.

The influence of aqueous solution of pristine C60 fullerene (C60FAS) on functional activity of lymphocytes from a healthy person was studied for the first time. By means of atomic force microscopy, it was found that C60FAS in a concentration of 0.1 mg/ml increases the stiffness of the lymphocyte membrane by 41% (p < 0.05) and lowers the functional activity of the plasmalemma surface, thereby constraining the use of its membrane material in physiological reactions using a hypotonic model in vitro. However, a cell retains the ability to regulate its volume and demonstrates relative resistance to hypo-osmotic stress. The resistance of lymphocytes in hypo-osmotic medium is facilitated by activation of the nucleus by C60 fullerene particles, which regulates the implementation of two consistent phases of an increase and decrease of cell volume, thereby retaining cell viability. All these indicate the impact of C60 fullerene on the cellular nucleus.

Tapping mode-atomic force microscopy and force spectroscopy were used for studies of the topography of the cell surface and elastic properties of lymphocytes from healthy donors and patients with chronic lymphoblastic leukemia. It was demonstrated that the decrease in lymphocytes stiffness in patients with chronic lymphoblastic leukemia by 51.4% (p<0.05) was accompanied by spatial modification of the cell surface, in particular, increase in the number of globular protrusions and depressions by 247 and 122%, respectively (p<0.05), in comparison with normal lymphocytes.

We propose and tested a method for studies of native blood cells by atomic-force microscopy in a humid chamber preserving viability, size, and shape of biological objects. The method has some advantages over scanning in a liquid cell: it allows studying non-fixed blood samples in the form of suspension of live cells and excludes mechanical and chemical influences on the cells.

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