An anaerobic, motile, gram-negative, rod-shaped, syntrophic, benzoate-degrading bacterium, strain SB, was isolated in pure culture with crotonate as the energy source. Benzoate was degraded only in association with an H2-using bacterium. The kinetics of benzoate degradation by cell suspensions of strain SB in coculture with Desulfovibrio strain G-11 was studied by using progress curve analysis....

A mathematical model of infiltrative tumour growth is investigated taking into account transitions between two possible states of malignant cells: proliferation and migration. These transitions are considered to depend on oxygen level in a threshold manner where high oxygen concentration allows cell proliferation, while concentration below a certain critical value induces cell migration. The in...

There is strong evidence demonstrating that nifedipine dissolved in ethanol selectively inhibits only L-type Ca2+ current. In addition, acute ethanol exposure reduces voltage-dependent calcium currents. In the present study, we investigated the antagonistic effect of fixed concentration of nifedipine dissolved in different concentration of ethanol on L-type Ca2+ current. In a Na+-K+ free soluti...

Regulation of siderophore production in response to iron concentration in the medium was examined. Threshold concentration was recorded for twenty fungi and three rhizobacterial pseudomonads. Organisms showed difference in threshold values at which they stopped siderophore elaboration. In nine fungi (3 aspergilli, 1 penicillium, N. crassa, F. dimerum and 3 mucors) siderophore production was rep...

The requirements on sunscreens have essentially changed, since some years ago it was demonstrated that approximately 50% of free radicals, that are formed in the skin by solar radiation, originate from the visible and infrared regions of the solar spectrum. In addition, a critical radical concentration threshold could be found. If this concentration, the free radical threshold value (FRTV), is ...

The nitrogen concentration of ultrathin gate oxides (sub-1.3 nm) was varied in a wide range (from 13 % to 23 %). The threshold voltage and the channel carrier mobility of advanced 65 nm technology CMOSFET transistors fabricated with these oxides were analyzed. It was observed that increasing the nitrogen concentration in the gate oxide results in a negative shift of the threshold voltage for bo...

The release of free cytosolic calcium is a secondary messenger for many cell functions. Here we study the coupling between the release of intracellular calcium and motility responses of the human neutrophil. Two groups of motility responses are studied: motility responses in the presence of adhesion, such as cell crawling and phagocytosis, and motility responses 'in suspension', such as pseudop...

The plasmodium of Physarum polycephalum reacts to various kinds of chemicals substances and moves towards or away from them. Threshold concentration of recognition of chemicals was examined in terms of membrane potential and of the averaged motive force of tactic movement by using a double-chamber method, i.e., a single plasmodium was placed between two compartments through a narrow ditch, and ...