Anti-tumor activity evaluation of novel chrysin-organotin compound in MCF-7 cells.

Chrysin (5,7-dihydroxylflavone, Chry) is a natural flavonoid extracted from plants and propolis. In this work, a novel chrysin-organotin (Chry-Sn) compound with enhanced anticancer activities was synthesized by the reaction of chrysin and triphenyltin chloride, and its potential anticancer effects against cancer cells were measured using various methods. Sulforhodamine B (SRB) results showed that chrysin and Chry-Sn had significant inhibition effects on the proliferation of MCF-7, A549 and HeLa human cancer cell lines in a dose- and time- dependent manner. These results suggested that Chry-Sn possessed enhanced anticancer effects. Hoechst 33258 staining and acridine orange staining results showed apoptosis and nuclei fragments significantly increased after being treated with chrysin and Chry-Sn respectively. Moreover, chrysin and Chry-Sn significantly increased ROS levels in MCF-7 cells. Western blot results showed that chrysin and Chry-Sn activated caspase 3 and induced autophagy by increasing LC3-II level. All results showed collectively that Chry-Sn could be a more promising drug than chrysin in anticancer treatment.

[Study on application of amphotericin B in the perforated whole-cell patch clamp technique].

OBJECTIVE: Established with amphotericin B perforated patch-clamp technique, to study the electrophysiological properties of calyx synapses. METHODS: In the present experiments, we studied the application of perforated patch clamp technique on the calyx synapses of mice with Amphotericin B. RESULTS: The use of Amphotericin B significantly slowed down the decay of channel currents and the optimum concentration was 400 microg/ml. CONCLUSION: The syudy developed a stable of perforated patch clamp whole cell recording technique, could be more effecitve, more real reaction neurons electrophysiological characteristics of the channel current. Our work might provide the basic information to future users studying the signal transmission and regulation of auditory system of rodents.

Nicotine dynamically modulates dopamine clearance in rat striatum in vivo.

Nicotine binds to nicotinic acetylcholine receptors on dopaminergic terminals to evoke dopamine (DA) release. The clearance of released DA occurs rapidly through reuptake into nerve terminals through the DA transporter (DAT). However, whether nicotine modulates DAT function in vivo is still not well understood. In the present study, we determined the effect of nicotine on DA clearance using in vivo amperometric recording in the striatum of urethane-anesthetized rats. Stable DA release was evoked by electrical stimulation of the medial forebrain bundle (MFB). Subsequently, nicotine or saline was administered with MFB stimulation at 10-min intervals for 60 min. Kinetic analysis revealed that nicotine decreased the amplitude of DA overflow and the maximal DA clearance rate (V(max)) in response to stimulation of 96 pulses at 80 Hz. Surprisingly, nicotine enhanced the maximal DA clearance rate (V(max)) by stimulation of 768 pulses at 80 Hz. Furthermore, we found that this paradoxical effect of nicotine on V(max) depended on the stimulation pattern. These results suggest that nicotine may exert its addictive role by dynamically modulating DAT function in vivo.

[Monoclonal antibodies prepared and used for detection of acute virus necrobiotic disease virus in scallop Chlamys farreri by indirect ELISA].

For developing monoclonal antibodies against acute virus necrobiotic disease (AVND) virus, mice of Balb/c strain were immunized with AVND virions which were isolated from the infected scallop Chlamys farreri. The spleen cells from immunized mice were then fused with NS-1 myeloma cells and the hybridomas were screened by means of enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assay (IFA). Finally, 4 stable MAbs of IgG isotype were obtained. Moreover, the combined position of these 4 MAbs to this virus was examined by immunogold electron microscopy (IEM). The results demonstrate that all 4 MAbs recognized epitopes on the envelope of the virions. Subsequently, a MAb-based ELISA was developed and used for detection of the infection rate and densities of the scallops which were sampled during different seasons from mid-April to mid-October, 2003. The result exhibited that both of the infection rate and infection densities sharply rose in mid-July and reached to the spikes, which right corresponds with their mortality during this period.

Optimization of a multi-channel puffer system for rapid delivery of solutions during patch-clamp experiments.

In biological experiments, especially in neuroscience research, it is important to manipulate the extracellular environment efficiently. We have developed a micro-puffing system for local drug delivery to single cells in electrophysiological experiments, and validated the kinetic properties of this instrument. Based on our results, the kinetics of the delivery of solutions and the territory controlled by this system are influenced by several factors: (1) inner diameter (I.D.) of the guide tubing; (2) I.D. of the puffing tip; (3) angle of the puffing tip; and (4) gravity or external pressure applied to the solution. The system can fully control a territory of 200 x 600 micrometer2. The minimum delay in response to drug delivery is 10-20 ms. Switching between different solutions takes less than 100 ms. The minimum volume of solution required by the system is 0.2 ml. Taken together, our results provide useful data for designing and using an efficient drug/solution delivery system in electrophysiological experiments.

[Histopathological research and immunofluorescence of AVND virus infection in cultured scallop Chlamys farreri].

The naturally infected scallops Chlamys farreri sampled during mass mortality in summer of 2003 was detected by means of histopathological and MAb-based immunofluorescence assay (IFA). The results of histological examination demonstrated that a series of histopathological changes including cell swelling, basophilic increase, disorder, partial sloughing and excessive sloughing were always observed in epithelia of many different organs, e.g. mantle, gills, stomach, intestine and kidney. Additionally, the infected tissues were applied for in situ detection of the "acute virus necrobiotic disease" (AVND) virus by means of specific MAb-based IFA, and the result demonstrated that this pathological changes or lesions were perfectly coincident with the positive cells (fluorescencing cells) . The positive cells were denser in some local area of epithelia, and exhibited serious pathological lesions, which would reveal the roles of this virus in pathogenesis and further confirm that the AVND virus is the main causative agent of mass mortalities among cultured scallop Chlamys farreri farmed in northern coast of China.