[Effects of phosphorus fertilizer on the root system and its relationship with the aboveground part of flue-cured tobacco].

Using 'Yuyan 10' as the material, the effects of different phosphorus fertilizer application on root characteristics of tobacco, such as root dry mass and the difference of dry matter distribution and mineral nutrient accumulation between its above and underground parts were investigated. The results showed that the growth of flue-cured tobacco root system and the distribution of dry matter to the aboveground part were significantly promoted by phosphorus fertilizer application. The application of 30 kg P2O5 · hm(-2) led to the maximums of root dry mass, root volume, root activity and the minimum of root to shoot ratio. The maximum nutrient accumulation rates of root and leaf appeared 57-66 days after transplanting and 44-55 days after transplanting, respectively. Phosphorus could not only promote the mineral nutrition absorption of tobacco and the earlier appearance of maximum nutrient accumulation, but significantly promote the nutrient accumulation of the aboveground part. But, the positive effects described above would be weakened when the amount of phosphorus fertilizer was more than 30 kg P2O5 · hm(-2). Therefore, it's necessary to control the amount of phosphorus application to improve the quality of tobacco leaves.

Study of the in vitro-in vivo correlation of Danshensu and protocatechuic aldehyde in a two-step release system.

A two-step release system (TSRS) for the compound Danshen, which has drug-release behavior that is in accordance with the circadian rhythms of cardiovascular disease, was developed by combining an effervescent osmotic pump tablet and a pulsed-released tablet into one hard capsule by our lab. An in vivo study indicated that after oral administration of TSRS, two peaks of the plasma concentration of both Danshensu (DS) and protocatechuic aldehyde (PA) were observed, which suggested that the drug plasma concentration-time curve could meet the requirements for chronotherapy of cardiovascular disease after the bed-time administration of such a device. High performance liquid chromatography using an ultraviolet (UV) detector was used to simultaneously determine the concentrations of DS and PA in plasma. This method was simple, convenient, and appropriate for the quality control of DS and PA. A linear correlation model was established based on the percent absorbant data and percent in vitro dissolution data. Because the drugs were released from the device in an osmotic pressure-dependent manner and absorbed rapidly, a reasonable linear regression relationship was observed between the in vitro and in vivo performances. The current study highlights the potential use of such a device for chronopharmaceutical drug delivery.

[Comparison of kinetic behavior in both plasma and tissue after intravenous administration of alpha-asarone in lipid emulsion and aqueous solution in rats and mice].

OBJECTIVE: To compare the pharmacokinetics and tissue distribution of alpha-asarone in lipid emulsion and aqueous solution for injection and study the feasibility of lipid emulsion of alpha-asarone as the parenteral drug delivery system. METHOD: HPLC was used to determine the drug concentration in rat plasma and mice tissues after intravenous (i.v.) administration of lipid emulsion and aqueous solution of alpha-asarone at a single dose (40 mg x kg(-1)), respectively. RESULT: The plasma concentration-time profiles of lipid emulsion and aqueous solution of alpha-asarone after intravenous administration of them are similar and the drug concentration-time data were fitted to a two-compartment open model. The results of tissues distribution showed that distribution contents of alpha-asarone from lipid emulsion and aqueous solution in vivo are similar in lungs but lipid emulsion increased the uptake in livers and spleens, and decreased the uptake in hearts and kidneys for alpha-asarone. CONCLUSION: The plasma concentration-time profiles of alpha-asarone in lipid emulsion and aqueous solution are similar, but lipid emulsion significantly altered the tissue distribution of alpha-asarone, which may be beneficial to decrease its potential toxicity to heart and kidney.