IN-VITRO IMMUNOTOXICITY AND CYTOTOXICITY OF TRICHOSANTHIN AGAINST HUMAN NORMAL IMMUNOCYTES AND LEUKEMIA-LYMPHOMA CELLS

Trichosanthin (TCS) is a ribosome-inactivating protein from root tubers of Trichosanthes kirilowii Maxim. In this paper, the effects of TCS on the viability of human peripheral blood immunocytess, on the proliferation of lymphocytes, and its cytotoxicity to twelve cell lines of lymphoma or leukemia had been observed. TCS at high concentration (>12.5 mu g/ml) affected the viability of human B lymphocytes, but not that of human peripheral blood mononuclear cells (PBMCs), T lymphocytes and granulocytes. Human peripheral blood-derived monocytes/macrophages were highly sensitive to TCS (ID50 at 1.70 mu g/ml). TCS suppressed lymphocyte proliferation stimulated by Concanavalin A (Con A) or lipopolysaccharide (LPS). Human T cell lines and macrophage cell lines were more sensitive (ID50 < 0.9 mu g/ml) to TCS than B cell lines and myeloid lines. These results suggest that selective cytotoxicity of TCS to human macrophages/monocytes may be implicated in anti-HIV activity, and that selectively killing some leukemia-lymphoma cells by TCS merit further evaluation in treatment of some lymphoma and leukemia.

A STUDY ON THE EFFECT OF LESIONS OF AREA-7 OF THE PARIETAL CORTEX ON THE SHORT-TERM VISUAL SPATIAL MEMORY OF RHESUS-MONKEYS (MACACA-MULATTA)

This research is focused on the contribution of area 7 to the short-term visual spatial memory. Three rhesus monkeys (Macaca mulatta) were trained in the direct delayed response task in which 5 delay intervals were used in each session. When each monkey reached the criterion of 90% correct responses in 5 successive sessions, two monkeys underwent a surgery while the other one received a sham operation as a control. In the first stage of the surgery, bilateral areas 7a, 7b and 7ip of the parietal cortex of two monkeys were precisely lesioned. After 7 days of recuperation, the monkeys were required to do the same task. The average percentage of correct responses in the lesioned animals decreased from 94.7% to 89.3% and 93.3% to 82.0% respectively (no significance, P > 0.05, n = 2). In addition, the monkeys' complex movements were mildly impaired. The lesioned monkeys were found to have difficulty picking up food from the wells. In the second stage, bilateral area 7m was lesioned. In the 5 postoperative sessions, the average percentage of correct responses in one monkey, with a relatively precise 7m lesion, decreased from 94.7% to 92.2% (no significance, P > 0.05), while the other monkey, with widely spread necrosis of lateral parietal cortex, showed an. obvious decline in performance, but still over the chance level. After 240 trials this monkey reattained the normal criterion. The results of this research suggest that the lesions of area 7 of the parietal cortex did not significantly affect the short-term visual spatial memory, which has been shown to be sensitive to lesions of the prefrontal cortex; they also support the notion of dissociation of spatial functions in the prefrontal and parietal cortices.

Rain igestion in axial flow compressors at part speed

New experimental work is reported on the effects of water ingestion on the performance of an axial flow compressor. The background to the work is the effect that heavy rain has on an aeroengine compressor when operating in a "descent idle" mode, i.e., when the compressor is operating at part speed and when the aeromechanical effects of water ingestion are more important than the thermodynamic effects. Most of our existing knowledge in this field comes from whole engine tests. The current work provides the first known results from direct measurements on a stand-alone compressor. The influence of droplet size on path trajectory is considered both computationally and experimentally to show that most rain droplets will collide with the first row of rotor blades. The water on the blades is then centrifuged toward the casing where the normal airflow patterns in the vicinity of the rotor tips are disrupted. The result of this disruption is a reduction in compressor delivery pressure and an increase in the torque required to keep the compressor speed constant. Both effects reduce the efficiency of the machine. The behavior of the water in the blade rows is examined in detail, and simple models are proposed to explain the loss of pressure rise and the increase in torque. The measurements were obtained in a low speed compressor, making it possible to study the mechanical (increase in torque) and aerodynamic (reduction in pressure rise) effects of water ingestion without the added complication of thermodynamic effects. Copyright © 2008 by ASME.

FIRST PASSAGE APPROXIMATION FOR NORMAL STATIONARY RANDOM PROCESSES.

A new approximate solution for the first passage probability of a stationary Gaussian random process is presented which is based on the estimation of the mean clump size. A simple expression for the mean clump size is derived in terms of the cumulative normal distribution function, which avoids the lengthy numerical integrations which are required by similar existing techniques. The method is applied to a linear oscillator and an ideal bandpass process and good agreement with published results is obtained. By making a slight modification to an existing analysis it is shown that a widely used empirical result for the asymptotic form of the first passage probability can be deduced theoretically.

Effect of flow-geometry on turbulence-scalar interaction in premixed flames

Turbulent combustion of stoichiometric hydrogen-air mixture is simulated using direct numerical simulation methodology, employing complex chemical kinetics. Two flame configurations, freely propagating and V-flames stabilized behind a hot rod, are simulated. The results are analyzed to study the influence of flame configuration on the turbulence-scalar interaction, which is critical for the scalar gradient generation processes. The result suggests that this interaction process is not influenced by the flame configuration and the flame normal is found to align with the most extensive strain in the region of intense heat release. The combustion in the rod stabilized flame is found to be flamelet like in an average sense and the growth of flame-brush thickness with the downstream distance is represented well by Taylor theory of turbulent diffusion, when the flame-brushes are non-interacting. The thickness is observed to saturate when the flame-brushes interact, which is found to occur in the simulated rod stabilized flame with Taylor micro-scale Reynolds number of 97. © 2011 American Institute of Physics.