RESUMEN
OBJECTIVE: To study the preparation of carboxylated multi-walled carbon nanotubes loaded with podophyllotoxin (PPT-CNTs-COOH) as well as the characteristics of the in vitro transdermal penetration. METHODS: PPT-CNTs-COOH was prepared by freezing milling method; IR, UV, XRD, and TGA were used to characterize the PPT-CNTs-COOH; HPLC method was used for determination of the content of podophyllotoxin loaded in the carboxylated multi-walled carbon nanotubes; franze diffusion cells method was used to determine the drug transdermal penetration rate. RESULTS: The IR spectrum of PPT-CNTs-COOH showed the main absorption peaks of PPT and CNTs-COOH and the peaks changed obviously. Compared with free PPT, the UV absorption peaks of PPT-CNTs-COOH changed obviously. The PPT content in the CNTs-COOH gel was 58.0 μg·mg-1; the transdermal penetration rate of PPT gel was 7.08 μg·cm-2·h-1 and that of the PPT-CNTs-COOH gel was 3.03 μg·cm-2·h-1; the skin retention of PPT-CNTs-COOH gel was 3.04 μg·cm-2, far less than the 1.52 μg·cm-2 of PPT gel. Mild irritation developed within 24 h following removal of the PPT-CNTs-COOH gel, and disappears after 72 h. CONCLUSION: Podophyllotoxin can successfully be loaded into the carboxylated multi-wall carbon nanotubes by using the frozen ball milling method. The product has remarkable sustained release effect in vitro and high retention in skin, which is beneficial to transdermal delivery.
RESUMEN
<p><b>OBJECTIVE</b>The aim of the study was to evaluate the anti-HBs persistence and the long term preventive efficacy after vaccination 23 years with plasma-derived hepatitis B vaccine.</p><p><b>METHODS</b>The study consisted of 261 children who were 5 - 9 years aged, from two primary schools in two townships of Xi'an. 126 children were randomly selected as vaccine group, and 135 children in control group. These children were followed up again in 2009. Excluding self-inoculation, the vaccine and control groups were 81 and 75, who was used to ask to recall details of their experience for vaccination and liver-related illnesses during past twelve years. Individuals who had anti-HBs titers less 10 mIU/ml, HBsAg, anti-HBc and HBV-DNA all were negative, were given a booster dose vaccine and retest for anti-HBs titer after one month.</p><p><b>RESULTS</b>After eliminated the interference of an early booster dose and vaccination outside the study, the positive rate of anti-HBs was 48.1% (39/81) in the vaccine group at year 23, higher than 34.7% (26/75) in control group. At year 23 after primary vaccination, 84.0% (21/25) individuals in the vaccine group whose anti-HBs and anti-HBc both are negative showed a stronger anamnestic response after received a booster dose, while 7.5% (3/40) in the control group. At year 23 after primary vaccination, none clinical case of hepatitis B was found among 194 individuals. However, anti-HBc positive rate in the vaccine group was 16.0% (13/81), while the rate in the control group was 30.7% (23/75) (χ(2) = 4.687, P < 0.05).</p><p><b>CONCLUSION</b>At 23 years after implemented a full course of plasma-derived hepatitis B vaccine, the recipients of vaccine were maintained anti-HBs at a high level or strong immunological memory.</p>