Multi-compartment linear circulation mathematical model for targeted drug delivery systems was established on the bases of compartment theory and mass conservation theory. The function formulas of drug concentration-time in blood and target organ were established. According to this model, the drug concentration-time curve for the target organ can be plotted with reference to the data on blood. Based on the target organ drug concentration-time curve,the pharmacokinetics parameters of the target organ can also be calculated by the statistical moment. We further detected the practicability of the models by using the experimental data of drug concentration-time curve in blood and target organ of microspheres. The drug concentration-time curve in blood and in target organ predicted by mathematical model was agreed with that observed.
Albumins ; administration & dosage ; Drug Delivery Systems ; Humans ; Microspheres ; Models, Theoretical ; Pharmacokinetics

The mechanism of drug release from swellable polymer was studied. The model which can explain the drug release from glassy polymer was developed by coupling drug diffusion equation and solvent diffusion equation. The effect of viscoelastic stress of polymer was also considered. The Deborah number and swelling interface number were used to describe the mechanism of drug release, especially relax controlled mechanism.
Delayed-Action Preparations ; Diffusion ; Drug Delivery Systems ; Models, Chemical ; Polymers ; chemistry ; Tablets

Sugar-containing monomer vinylbenzylglycosylallyamide (VBG) was synthesized by vinylbenzyl amine and delta-gluconolactone in dimethylformamide(DMF) solution. The sugar-based hydrogel was prepared by free radical crosslinking copolymerization of VBG, itaconic acid (IA) and acrylamide (AM). The release properties of Aspirin from xerogels matrices and from hydrogel in different pH solutions and different concentration NaCl solutions were studied respectively. The release mechanism of Aspirin was further confirmed by evaluating the n value in Peppas equation. The results indicated that the drug release increased with the increase of pH values and with the decrease of NaCl concentration.
Acrylic Resins ; chemistry ; Anti-Inflammatory Agents, Non-Steroidal ; administration & dosage ; chemistry ; Aspirin ; administration & dosage ; chemistry ; Delayed-Action Preparations ; chemical synthesis ; chemistry ; Humans ; Hydrogel, Polyethylene Glycol Dimethacrylate ; chemical synthesis ; chemistry ; Hydrogen-Ion Concentration ; Succinates ; chemistry ; Vinyl Compounds ; chemistry

Sugar-containing monomer glycosylallylamide (AAG) was synthesized by allyl amine and delta-gluconolactone in dimethylformamide (DMF) solution. The sugar-based hydrogels were prepared by free radical crosslinking copolymerization of AAG and acrylamide (AM). The release properties of Aspirin from xerogels matrices were studied and the release mechanism of Aspirin was further identified by evaluating the n value in Peppas equation. The results indicate that the drug release decreases with the increase of the sugar content of hydrogel.
Acrylamide ; chemical synthesis ; chemistry ; Aspirin ; pharmacokinetics ; Delayed-Action Preparations ; Gluconates ; chemical synthesis ; chemistry ; Hydrogels ; chemical synthesis ; chemistry ; Lactones ; Polymers ; chemical synthesis ; chemistry

Germ cells make two major decisions when they move from an indeterminate state to their final stage of gamete production. One decision is sexual commitment for sperm or egg production, and the other is to maintain mitotic division or entry into meiosis. It is unclear whether the two decisions are made as a single event or separate events, because there has been no evidence for the presence of germ cell sex prior to meiosis. Here we report direct evidence in the fish rainbow trout that gonia have distinct sexuality. We show that dazl expression occurs in both male and female gonia but exhibits differential intracellular distribution. More strikingly, we show that boule is highly expressed in male gonia but absent in female gonia. Therefore, mitotic gonia possess sex, sperm/egg decision and mitosis/meiosis decision are two independent events, and sperm/egg decision precedes mitosis/meiosis decision in rainbow trout, making this organism a unique vertebrate model for mechanistic understanding of germ cell sex differentiation and relationship between the two decisions.
Animals ; Female ; Fish Proteins ; genetics ; Gene Expression Regulation ; Male ; Meiosis ; Oncorhynchus mykiss ; genetics ; physiology ; Ovary ; cytology ; metabolism ; Ovum ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; RNA-Binding Proteins ; genetics ; Sex Determination Processes ; Spermatozoa ; cytology ; metabolism ; Testis ; cytology ; metabolism