RESUMO
Konjac glucomannan (KGM) can be degraded by colon-specific enzymes in the colonic environment, making it one of the materials for treating colonic diseases, which has attracted more and more attention. However, during drug administration, especially in the gastric environment and due to its easy swelling, the structure of KGM is usually destroyed and the drug is released, thereby reducing the bioavailability of the drug. To solve this problem, the easy swelling and drug release properties of KGM hydrogels are avoided by creating interpenetrating polymer network hydrogels. In this study, N-isopropylacrylamide (NIPAM) is first formed into a hydrogel framework under the action of a cross-linking agent to stabilize the gel shape before the gel is heated under alkaline conditions to make KGM molecules wrap around the NIPAM framework. The structure of the IPN(KGM/NIPAM) gel was confirmed using Fourier transform infrared spectroscopy (FT-IR) and x-ray diffractometer (XRD). In the stomach and small intestine, it was found that the release rate and swelling rate of the gel were 30% and 100%, which were lower than 60% and 180% of KGM gel. The experimental results showed that this double network hydrogel has a good colon-directed release profile and fine drug carrier ability. This provides a new idea for the development of konjac glucomannan colon-targeting hydrogel.
RESUMO
The 37/67-kDa laminin receptor precursor (LRP)/laminin receptor (LR) is a cell surface receptor for cellular prion proteins and misfolded pathological prions. Previous research has shown that blocking or decreasing LRP/LP levels by anti-LRP/LR antibodies or small interfering RNAs (siRNAs) can prolong the incubation phase of experimental prion infection. This study aimed to investigate potential mechanisms contributing to prion resistance/susceptibility by using the rabbit, a species unsusceptible to prion infection, as a model. We investigated the expression level and distribution of LRP/LR in rabbit tissues by real-time polymerase chain reaction and by immunochemical analysis with a monoclonal anti-67 kDa LR antibody. Our results showed LRP/LR mRNA expression in all the tissues examined. Very low LRP/LR expression levels were observed in central nervous system (CNS) tissues, whereas high expression levels were observed in reproductive and digestive tissues, which differed from the expression patterns that have been reported for prion-susceptible animals. The immunochemical staining results were generally consistent with the mRNA findings, although no LR protein was detected in CNS tissues. Our findings provide a basis for further studies on prion resistance in rabbits and other animal species.