Improved tolerance of maize (Zea mays L.) to heavy metals by colonization of a dark septate endophyte (DSE) Exophiala pisciphila.

Dark septate endophytes (DSE) are ubiquitous and abundant in stressful environments including heavy metal (HM) stress. However, our knowledge about the roles of DSE in improving HM tolerance of their host plants is poor. In this study, maize (Zea mays L.) was inoculated with a HM tolerant DSE strain Exophiala pisciphila H93 in lead (Pb), zinc (Zn), and cadmium (Cd) contaminated soils. E. pisciphila H93 successfully colonized and formed typical DSE structures in the inoculated maize roots. Colonization of E. pisciphila H93 alleviated the deleterious effects of excessive HM supplements and promoted the growth of maize (roots and shoots) under HM stress conditions, though it significantly decreased the biomass of inoculated maize under no HM stress. Further analysis showed that the colonization of E. pisciphila H93 improved the tolerance of maize to HM by restricting the translocation of HM ions from roots to shoots. This study demonstrated that under higher HM stress, such a mutual symbiosis between E. pisciphila and its host (maize) may be an efficient strategy to survive in the stressful environments.

beta2-integrins mediate a novel form of chemoresistance in cycloheximide-induced U937 apoptosis.

In this study with cycloheximide (CHX, an inhibitor of protein synthesis) and the human leukaemic cell line U937, a novel form of chemoresistance, which we termed sudden drug resistance (SDR), was identified using Hoechst33258 staining, Western blot and DNA Ladder. CHXhigh (10-100 microg/ml)-induced apoptosis can spontaneously subside after 4-6 h or can be inhibited by short-term preincubation with CHXlow (2.5 microg/ml). Unlike typical multidrug resistance, SDR is not caused by reduced drug accumulation or altered protein expression, and may be associated with a non-P-glycoprotein mechanism. To uncover this underlying mechanism, we focused on U937 cell aggregation promoted by CHX, because cell adhesion has been suggested to influence cell survival and prevent apoptosis. EDTA, or anti-CD18 monoclonal antibody, but not EGTA, acetylsalicylic acid or RGDS tetrapeptide, abrogated this homotypic aggregation and greatly increased CHX-induced apoptosis in a time-dependent manner, while fibrinogen and soluble intercellular adhesion molecule-1 exerted opposite effects. These results establish that beta2-integrin engagement is a key mediator of SDR, although it may be non-exclusive. This finding supplements the classical basis of chemoresistance and may provide another opportunity for improved leukemia therapy.

Magnetic field tomography of cortical and deep processes: examples of "real-time mapping" of averaged and single trial MEG signals.

Magnetic field tomography (MFT) provides 3-dimensional estimates of brain activity, from non-contact, non-invasive measurements of the magnetic field generated by coherent electrical activity in the brain. MFT analysis of averaged auditory "odd-ball" data show cortical and deep activation, presumably from the amygdala and hippocampus. These results are compared with MFT estimates obtained from a patient who had undergone lobectomy which removed these structures. The variability from subject to subject is confounded by variability between trials for the same subject; the relationship between the averaged and single trials is probed by bi-hemispheric simultaneous measurements performed under the same odd-ball paradigm and by MFT analysis of auditory evoked data and interictal epileptic activity.

Activation sequence of discrete brain areas during cognitive processes: results from magnetic field tomography.

Magnetic field tomography is a technique for extracting 3-dimensional estimates of current density in the brain, from non-contact, non-invasive measurements of the magnetic field generated by the brain. It allows visualisation of both cortical and subcortical focal activation patterns at millisecond intervals, and the relative time difference between active cortical areas. We have used this technique to study the activation history of discrete brain regions associated with the preparation for, initiation and inhibition of movement, and movement itself in a CNV paradigm. The strongest focal activities are found within well defined cortical regions, namely the auditory (A1), sensorimotor (SM1), medial parietal area (MPA) and anterior supplementary motor area (SMA). For the movement condition, activation history differs for the warning stimulus and the stimulus initiating movement.

[Antithrombotic effect of Gynostemma pentaphyllum].

Human blood samples were investigated in vitro to observe the antithrombotic effect of water extract of Gynostemma pentaphyllum (GP). The results showed that GP could inhibit significantly the platelet aggregation induced by ADP and compound agonists (P < 0.05), accelerate obviously the disaggregation (P < 0.05) and inhibit effectively the experimental thrombosis (P < 0.05). The delayed effects of GP on KPTT, PT, TT, AT, RVV-RT, RVV-CT suggested that this drug could decrease the activity of multiple coagulation factors. And it showed that GP could accelerate the erythrocyte electrophoresis rate. This study revealed that GP is an antithrombotic agent affecting the links of thrombotic chain which is worthwhile to be studied further.