Impact of fertilization on ammonia volatilization and N2O emissions in an open vegetable field.

A field experiment with different nitrogen fertilization rates and mitigation measures was conducted in an open-ground vegetable field on the North China Plain to investigate the effects of nitrogen application level and management practices on ammonia volatilization and N2O emission. Reducing the nitrogen fertilization rate by 20% and by 50% decreased ammonia volatilization by 25.7% and 48.0%, respectively, during the spring-sowed cucumber growth period. Amendment with combined inhibitors and biochar decreased ammonia volatilization loss by 10.0% and 6.1%, respectively. Reducing nitrogen fertilization rate by 20% and 50% decreased N2O emission by 28.8% and 61.0% during the spring-sowed cucumber growth period. Addition of combined inhibitors decreased N2O emission by 58.9%, while it was increased by 14.1% with biochar addition. Under the same application method of banding application, replacing 30% nitrogen fertili-zer with organic manure did not show any significant mitigation for ammonia volatilization and N2O emission. For the intensively managed vegetable fields, reducing the nitrogen application rate appropriately was the most effective measure to reduce ammonia volatilization and N2O emission.

[Evaluation of antifungal chemotherapeutic effects on fungal keratitis by confocal microscopy].

OBJECTIVE: To evaluate the validity of confocal microscopy in estimating curative effect and in directing the treatment for fungal keratitis in the process of antifungal chemotherapy. METHODS: Fifty-eight patients, who were confirmed fungal infection by confocal microscopy, were selected from 328 patients with fungal keratitis. All patients received routine topical and/or oral antifungal medication, and were examined by confocal microscopy once a week and one week after discontinuation of the treatment. The density of hyphae in the corneal lesion, the configuration of inflammatory cells and keratocyte were recorded. Antifungal chemotherapy was adjusted according to examination results and medicines were changed accordingly. If no hyphae were detected by confocal microscopy, antifungal medication was maintained for one week and then discontinued. All patients were followed up for two months to ensure no relapse of fungal infection. RESULTS: Fifty three patients were cured. The area of corneal lesions began to reduce 7 days after the beginning of antifungal chemotherapy. Confocal microscopy examination revealed that the hypha positive sites and the density of hypha were reduced gradually; inflammatory cells also decreased, the configuration of corneal lesion was transformed from asymmetry to symmetry; and normal keratocytes could be detected gradually. After 14 days of treatment, ulcers healed up in 37 cases and no hyphae and inflammatory cells were found in 23 cases. After 28 days of treatment, all corneal ulcers healed up; hyphae and inflammatory cells were completely disappeared in 31 patients, but a few hyphae still could be found in 22 patients. Antifungal chemotherapy was tapered gradually if no hyphae and inflammatory cells were detected by confocal microscopy. There was no relapse of fungus infection during 2-month follow-up. Infection deteriorated in the other five patients within 7 days, which showed increased density of hypha and inflammatory cells under confocal microscopy examination. All of them were treated with a penetrating keratoplasty to save the eyeball. CONCLUSIONS: Confocal microscopy is an ideal method for the evaluation of curative effects of fungal keratitis in the process of antifungal chemotherapy. This is also a valuable objective tool in directing antifungal medication.

[Inhibition of corneal neovascularization by liposomes mediated plasmid encoding human endostatin].

OBJECTIVE: To evaluate the effect of liposomes mediated plasmid encoding endostatin (ES) for inhibiting experimental corneal neovascularization (CNV). METHODS: Thirty New Zealand albino rabbits were sutured on the superior cornea. Animals were randomly divided into 3 groups. Different reagents were injected at each group:liposomes and plasmid encoding human ES complex in the group 1, liposomes and carrier plasmid complex in the group 2 and saline in the group 3. The occurrence and development of CNV were observed by slit-lamp microscope 3, 7, 14, 21 and 28 days after suturing, the size of CNV area was measured and calculated. Immunohistochemistry was used to detect the ES protein expression in cornea and limbus at different time points. RESULTS: The appearance time of CNV was (6.85 +/- 0.69) d in group 1, (3.43 +/- 0.53) d in group 2 and (3.14 +/- 0.69) d in group 3. Significant difference in appearance time of CNV was found between the group 1 and the others (F = 100.24, P < 0.05). No significant difference was found between the group 2 and group 3. The size of CNV areas of group 1 were significantly smaller than that of the groups 2 and 3 at every time point (F = 72.662, 75.601, 27.729; P < 0.05). ES protein expression in group 1 was detected at superior limbus and the cornea, with the highest level of expression at 3 days, gradually decreased after 7 days and had a very small quantity of expression at 28 days. ES protein expression was not detected in the groups 2 and 3. CONCLUSION: Liposomes mediated plasmids encoding ES can be transferred to cornea and limbus tissues by subconjunctival injection, with the highest levels of expression at 3 days posttransfer and can suppress corneal neovascularization at certain degrees.

[Liposomes mediated plasmids encoding human endostatin inhibits endothelial cell proliferation].

OBJECTIVE: To evaluate the effect of liposomes mediated plasmids encoding endostatin on endothelium cell proliferation. METHODS: Cationic liposomes mediated endostatin (ES) expression of plasmid PCDNA(3)-ES was transferred to Cos-7 cells. ES protein expression was tested with immune dot blot. Human umbilical vein endothelial cells (ECV-304) was transfected by liposomes mediated PCDNA(3)-ES. The ES protein expression was tested with immunofluorescence staining. The effect of the transfection on cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) method. The effect of ES on cell cycle after ES transfection was examined by flow cytometric analysis. RESULT: ES protein expression was detected in ES transfected COS-7 cells and supernatants. The ES expression in ECV-304 cells was reached the highest level on the second day after transfection. The proliferation of ECV-304 was inhibited by ES transfection with an increase in the ratio of G(0)/G(1) phase and a decrease in the ratio of the S phase. CONCLUSION: Liposomes mediated plasmids encoding ES can be transferred to endothelial cells and showed to inhibit proliferation of the endothelium cells.