[Characteristics of DNA adsorption and desorption in variable and constant charge soil colloids].

The characteristics of adsorption and desorption of DNA by Red soil colloid, Latosol colloid, Chao colloid and Cinnamon colloid at different pH values were studied using a batch method. It showed that there was an increase of solution pH after adsorption of DNA by the four soil colloids in both NaCl and KCl electrolyte systems. The increasing ranges of pH values were in order of Red soil colloid > Latosol colloid > Chao colloid > Cinnamon colloid, and NaCl electrolyte system > KCl electrolyte system. The amounts of DNA adsorption on soil colloids decreased with the increase of pH value. The maximum amounts of DNA adsorption in different colloids were about 13.1-14.8 microg x mg(-1) when pH values were 2-4. The decreasing ranges of the amounts of DNA adsorption were about 5.5 microg x mg(-1) in NaCl electrolyte system and 2.1 Mg x mg(-1) in KCl electrolyte system in Red soil colloid and Latosol colloid after the rising of equilibrium solution pH from 4.2 to 8.6, whereas the remarked decreasing ranges of the adsorption amounts of DNA were about 8.3-12.2 microg x mg(-1) on Chao colloid and Cinnamon colloid in two electrolyte systems. The decreasing ranges of DNA adsorption were in order of the constant charge (Chao soil and Cinnamon) colloids > the variable charge (Red soil and Latosol) colloids. The differences of desorption on the variable and the constant charge colloids are very significant while the DNA adsorbed was desorbed with NaOAc solution and NaH2 PO4 solution. The desorption percent desorption of DNA as NaH2PO4 desorbent was 23.5%-40.2% larger on the variable charge colloids than 8.8%-21.6% on the constant charge of colloids at the three different solution pH values of 3, 5 and 7, while that as NaOAc desorbent was 72.3%-85.9% larger on the constant charge colloids than 10%-24.5% on the variable charge colloids. These results implied that the ligand exchange played a more important role in DNA adsorption on the variable charge colloids, and electrostatic interactions did on the constant charge colloids. This is the differences of DNA adsorption and desorption on different charge colloid surfaces.

[Study on rapid generation of dendritic cells from K562 cell line induced by A23187 alone].

OBJECTIVE: To explore a simple, rapid and efficient way to generate dendritic cells from leukemic cells. METHODS: K562 cells were cultured with calcium ionosphere A23187 alone, A23187 plus GM-CSF, or a DC differentiation cocktail consisting of GM-CSF, IL-4 and TNF-alpha, respectively. The expression of surface markers of induced DCs was analyzed by flow cytometry. The K562-DCs stimulating the proliferation of allo-genetic naive T cells and inducing cytotoxicity of T cells were determined by MTT assay. RESULTS: Microscopic examination revealed that under all the three culture conditions, K562 cells became displaying DC morphology. At 72 hours in the two culture systems containing A23187, there were higher proportions of cells with dendritic morphology [(69.5 +/- 17.2)% and (73.1 +/- 13.9)%, respectively] than that in the cocktail system [(28.5 +/- 12.3)%] (P < 0.05). And the same did when cultured for 7 days [(69.5 +/- 17.2)%, (73.1 +/- 13.9)% respectively vs (51.2 +/- 10.7)%, P < 0.05]. In the 7-day cultures, the percentage of CD1a expressing cells was lower [(8.2 +/- 2.3)% and (10.3 +/- 5.1)% vs (17.2 +/- 1.6)%, respectively] while the CD83 expressing cells was higher [(85.6 +/- 8.8)% and (82.4 +/- 9.1)% vs (77.4 +/- 12.9)%, respectively] compared with that in the cocktail system (P < 0.05). No significant difference was found in the allogeneic T cell proliferation response and induced T cell cytotoxicity between A23187 containing and cocktail groups (P > 0.05). CONCLUSIONS: A23187 treatment is a simple, rapid and efficient in vitro strategy for inducing dendritic cell from leukemic cells.

[Effects of lactation, lactation-cessation and lactation-cessation-lactation paradigms on hypothalamic orexin-A immunoreactive neurons in rats].

Orexin-A is a novel neuropeptide produced by neurons mainly located in lateral hypothalamic area that potently facilitates appetite and food intake. The purpose of this study was to investigate the possible change in orexin-A immunoreactivity in suckling-induced hyperphagia. By using immunohistochemistry and image analysis techniques we examined orexin-A-like immunoreactivity in a series of rat brain sections corresponding to the hypothalamus in groups of non-lactating, lactating, lactating with overnight cessation of suckling, lactating and cessation followed by resumed short-term sucklings. Long-term lactation significantly increased daily food intake on day 3 (81%) and day 11 (180%) postpartum compared to that in non-lactating postpartum rats, whereas daily food intake was significantly decreased by overnight cessation of suckling on day 11 postpartum in long-term lactating rats (45%). Moreover, long-term lactating rats on day 12 postpartum exhibited significantly greater number and higher mean staining intensity of orexin-A immunoreactive neurons than those of non-suckling postpartum rats (P<0.001 and P<0.05, respectively). Overnight cessation of lactation in rats on day 12 postpartum significantly decreased both the number and mean staining intensity of orexin-A immunoreactive neurons compared to those in long-term lactating group of rats (P<0.001 and P<0.05, respectively), similar to the levels in the non-lactating postpartum rats. Resumed lactation for 2 and 5 h after overnight cessation of lactation significantly increased the number (P<0.001 and P<0.05, respectively) and mean staining intensity (P<0.05) of orexin-A immunoreactive neurons compared to those in the rats without resumed lactation. Both long-term lactation and short-term resumed suckling enhanced orexin-A immunoreactivity in the hypothalamus in rats, and overnight cessation of lactation down-regulated the increased orexin-A immunoreactivity induced by long-term lactation. Suckling may regulate orexin-A expression in the hypothalamus and the increased orexin-A may be involved in hyperphagia in lactating rats, suggesting the possibility of the existence of some neural-humoral links between suckling and hypothalamic orexin-A-immunoreactive neurons.