Field-driven tracer diffusion through curved bottlenecks: fine structure of first passage events.

Using scaling arguments and extensive numerical simulations, we study the dynamics of a tracer particle in a corrugated channel represented by a periodic sequence of broad chambers and narrow funnel-like bottlenecks enclosed by a hard-wall boundary. The tracer particle is affected by an external force pointing along the channel, and performs an unbiased diffusion in the perpendicular direction. We present a detailed analysis (a) of the distribution function of the height above the funnel's boundary at which the first crossing of a given bottleneck takes place, and (b) of the distribution function of the first passage time to such an event. Our analysis reveals several new features of the dynamical behaviour that are overlooked in the studies based on the Fick-Jacobs approach. In particular, trajectories passing through a funnel concentrate predominantly on its boundary, which makes first-crossing events very sensitive to the presence of binding sites and microscopic roughness.

[Haemodynamics during kidney transplantation and general anaesthesia in combination with epidural block and without it in pediatric patients].

RESEARCH OBJECTIVE: To compare haemodynamic effects of general anaesthesia in combination with epidural block and without it during kidney transplantation in Pediatric patients. METHODS: 61 Pediatric patients undergoing kidney transplantation were divided into two groups. General anaesthesia with sevoflurane, propofol, phentanilum and regional ropivacaine epidural block were used in the group 1. General anaesthesia was used only in the group 2. Haemodynamic parameters were assessed: Arterial blood pressure, stroke volume, central venous pressure and cardiac index. RESULTS: Both techniques of anaesthesia were adequate. CONCLUSION: regional ropivacaine epidural block and general anaesthesia combination provides more stable haemodynamic parameters than general anaesthesia single use.

[Computer morphometry of lymphocytes in the diagnosis of chronic transplant nephropathy].

AIM: to assess the role of immunological mechanisms in the development and progression of chronic transplant nephropathy (CTN) and the prognostic value of rapid computer morphometry of lymphocytes in predicting the risk of renal allograft rejection. SUBJECTS AND METHODS: Thirty-seven renal graft recipients (29 males and 8 females; mean age 35.9 +/- 2.2 years; mean time after renal allografting 19.9 +/- 2.7 months). Twenty-three patients had satisfactory renal graft function; 14 patients were diagnosed as having CTN. A control group included 30 apparently healthy individuals. Along with physical examination, vital computer phase morphometry (CPM) of peripheral blood immunocompetent cells was carried out in all the patients. RESULTS: Small and average cells were predominant in the T and B lymphocyte populations. In CTN, there were increases in diameter, perimeter, and area and decreases in the phase height and volume of B lymphocytes, which is indicative of their activation. There was a predominance of average B lymphocytes in CTN. CONCLUSION: Vital CPM of peripheral blood immunocompetent cells may be used for the early diagnosis and prediction of CTN development.