ABSTRACT
To study the rheological properties of sucrose acetate isobutyrate (SAIB) in situ gel and the influencing factors. Measurements of shear stress and viscosity were carried out at different shear rate. The rheological properties of SAIB solution were similar to those of Newtonian fluid. The factors such as the type of solvent, concentration, additive, drug and temperature had effect on the rheological properties. Ethanol was a suitable solvent compared with ethyl lactate and N-methylpyrrolidone (NMP). The solution viscosity of SAIB was reduced from 1.29 to 0.11 Pa x s with only increasing the content of ethanol from 10% to 20%. Polylactic acid (PLA) and risperidone could increase the intermolecular force and viscosity. However, adding 10% (w/w) PLA, the initial release of risperidone was reduced from 20.2% to 3.5%. The solution viscosity reduced significantly by stepping up the temperature. The results obtained support the using of SAIB is satisfactorily injectable in situ gel formulation.
Subject(s)
Antipsychotic Agents , Delayed-Action Preparations , Drug Carriers , Ethanol , Lactates , Lactic Acid , Polyesters , Polymers , Pyrrolidinones , Rheology , Risperidone , Solvents , Sucrose , Chemistry , Temperature , ViscosityABSTRACT
<p><b>OBJECTIVE</b>To construct a mouse that specifically expresses Cre recombinase in hepatocyte.</p><p><b>METHODS</b>A hepatocyte specific transgenic construct containing mouse albumin promoter, the Cre recombinase gene and the poly (A) of human growth factor gene was generated. The linearized constructs were introduced into the fertilized eggs by microinjection to obtain the transgenic mice. The transcriptional specificity of Cre recombinase was detected by reverse transcription polymerase chain reaction (RT-PCR). The expression and function of Cre recombinase were detected by PCR and Southern Blot after crossing the Alb-Cre transgenic mice with the Smad4 conditional knockout mice.</p><p><b>RESULTS</b>The linearized constructs were microinjected into 837 fertilized eggs, and then the 797 effective eggs of microinjected eggs were implanted into the oviducts of 27 pseudo pregnant mice. In the 53 offspring, there were 6 mice carrying the transgene identified by polymerase chain reaction (PCR) and Southern Blot. Cre recombinase transcripts were detected in the livers and testis of the Alb-Cre transgenic mice using RT-PCR. The Cre recombinase was expressed in the livers of the double heterozygous for Alb-Cre and Smad4 floxed allele, and the exon 8 floxed by loxP site was deleted.</p><p><b>CONCLUSION</b>A hepatocyte-specific Cre transgenic mouse was generated successfully. The Cre recombinase expressed specifically in liver and could mediate the recombination between loxP sites in vivo.</p>
Subject(s)
Animals , Female , Humans , Mice , Hepatocytes , Metabolism , Integrases , Genetics , Mice, Transgenic , Viral Proteins , GeneticsABSTRACT
The transgenic mice that express Cre recombinase in a tissue specific manner is a powerful tool in generating the conditional gene knockout mice. The rat insulin promoter was cloned target the expression of Cre in pancreatic tissue. The Cre gene was modified by adding the nuclear localization signal and the sequence for initiation by eukaryotic ribosomes at 5' terminal of the Cre gene. Cre gene was linked to the intron of human growth factor gene. This construct was introduced into the mouse eggs using microinjection. Seven mice were identified as founders carrying the Cre gene by PCR. The results of RT-PCR showed that the transgenic mouse from one founder could transcribe the foreign gene in pancreas. The Southern blot analysis indicated that the Cre recombinase expressed in pancreas of the transgenic mouse was functional.