Preparation and in vitro/in vivo characterization of enteric-coated nanoparticles loaded with the antihypertensive peptide VLPVPR.

Our previous study revealed that the peptide Val-Leu-Pro-Val-Pro-Arg (VLPVPR), which was prepared using deoxyribonucleic acid recombinant technology, effectively decreased the blood pressure of spontaneous hypertensive rats; however, the effect only lasts 6 hours, likely due to its low absorption in the gastrointestinal tract. To overcome this problem, the purpose of this study was to characterize (methoxy-polyethylene glycol)-b-poly(D,L-lactide-co-glycolide)-b-poly(L-lysine) nanoparticles as in vitro and in vivo carriers for the effective delivery of VLPVPR. In our study, the VLPVPR nanoparticles were prepared using a double emulsion method, coated with Eudragit S100, and freeze-dried to produce enteric-coated nanoparticles. The optimized parameters from the double emulsion method was obtained from orthogonal experiments, including drug loading (DL) and encapsulated ratio (ER) at 6.12% and 86.94%, respectively, and the average particle size was below 100 nm. The release experiment demonstrated that the nanoparticles were sensitive to pH: almost completely released at pH 7.4 after 8 hours, but demonstrated much less release at pH 4.5 or pH 1.0 in the same amount of time. Therefore, the nanoparticles are suitable for enteric release. In vivo compared with the untreated group, the medium and high doses of orally administered VLPVPR nanoparticles reduced blood pressure for more than 30 hours, demonstrating that these nanoparticles have long-lasting and significant antihypertensive effects in spontaneously hypertensive rats.

[Serotype distribution of non-polio enterovirus in patients with acute flaccid paralysis during 2011-2012 in Hebei Province, China].

This study aims to investigate the serotype distribution of non-polio enterovirus (NPEV) isolated from patients with acute flaccid paralysis (AFP) during 2011-2012 in Hebei Province, China and to analyze the relationship between these viruses and AFP. NPEV strains were isolated from the stool specimens from AFP cases in Hebei using human rhabdomyosarcoma cells (RD) and the mouse cell line expressing the gene for the human cellular receptor for poliovirus (L20B) according to the WHO requirements. The nucleotide sequence of VP1 region was determined, and the serotypes of NPEV were identified by molecular typing. The results showed that among the 82 strains of NPEV isolated from the AFP cases during 2011-2012, 42 isolates (55.3%) were identified as human enterovirus A (HEV-A), which were classified into 4 serotypes, 34 (44.7%) as human enterovirus B (HEV-B), which were classified into 13 serotypes, 2 as adenovirus, and 4 were untyped; human enteroviruses C and D were not found in these cases. Enterovirus A71 (EV-A71) was the main type of HEV-A, accounting for 85.7% of all HEV-A strains. HEV-A, especially EV-A71, was predominant among the NPEV strains isolated from AFP patients during 2011-2012 in Hebei Province.