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Biomedical subjects

X L Yan

Publications and source records attributed to X L Yan.

8 recordsLinked to original sources
PubMed2001

Chitosan-alginate films prepared with chitosans of different molecular weights.

Chitosan-alginate polyelectrolyte complex (CS-AL PEC) is water insoluble and more effective in limiting the release of encapsulated materials compared to chitosan or alginate. Coherent CS-AL PEC films have been prepared in our laboratory by casting and drying suspensions of chitosan-alginate coacervates. The objective of this study was to evaluate the properties of the CS-AL PEC films prepared with chitosans of different molecular weights. Films prepared with low-molecular-weight chitosan (Mv 1.30 x 10(5)) were twice as thin and transparent, as well as 55% less permeable to water vapor, compared to films prepared with high-molecular-weight chitosan (Mv 10.0 x 10(5)). It may be inferred that the low-molecular-weight chitosan reacted more completely with the sodium alginate (M(v) 1.04 x 10(5)) than chitosan of higher molecular weight. A threshold molecular weight may be required, because chitosans of Mv 10.0 x 10(5) and 5.33 x 10(5) yielded films with similar physical properties. The PEC films exhibited different surface properties from the parent films, and contained a higher degree of chain alignment with the possible formation of new crystal types. The PEC films exhibited good in vitro biocompatibility with mouse and human fibroblasts, suggesting that they can be further explored for biomedical applications.

Animals↗
PubMed1997

[Immune response of rubella vaccine in the populations with different age groups].

The natural immunity status in different age groups was investigated. The positive rate of HI antibody under the age of 4 was less than 25%. The natural immunity level increased gradually with age and the positive rate of the antibody reached 80% among the group aged 13-25. Rate of seroconversion was 100% in any age group one month after immunization, and GMT rose from 13.33 to 243.16. It was suggested that immunogenicity of domestic attenuated live rubella vaccine BRD II was satisfactory. For the population with positive-antibody before immunization, the total GMT rose from 189.59 to 259.00 after vaccination and the difference between immunization before and after was highly significant. According to the above result, we suggested that the vaccination strategy for rubella among young children and women of child-bearing age should be implemented.

Adolescent↗
PubMed1993

[Studies on the chemical constituents of Euonymus mupinensis].

Eight compounds have been isolated from Euonymus mupinensis. Their structures were identified by means of physico-chemical and spectral analysis. They are wilforlide A (I), wilforlide B (II), olean-12-en-3,29-diol (III), olean-3-oxo-29-ol (IV), stigmastan-3-one (V), stigmastan-3,6-dione (VI), beta-sistosterol (VII) and beta-sistosterol-3-O-beta-D-glucopyranoside (VIII). Compound IV is a new compound, named as mupinensisone. Compounds I-VIII were isolated for the first time from this plant. 13C-NMR chemical shifts of compounds V and VI were assigned for the first time.

Antineoplastic Agents, Phytogenic↗
PubMed1992

[Serological epidemiologic surveillance on filariasis by ELISA].

In 1984-1990 longitudinal or sectional serological surveillance on filariasis by ELISA with Brugia malayi adult antigen was carried out in 6 villages, Yuhang County, Zhejiang Province, where malayan filariasis had been under control. During that period the microfilaraemia rate of inhabitants had been declining continuously till nil, the positive rate and mean optical density (OD) value in ELISA for positive inhabitants concurrently declined year by year, especially for children under age of 10. By the 5th year after control both the positive rate and mean OD value were close to those of healthy persons living in nonendemic areas of filariasis, no positivity was found in children. In the meantime, ELISA was used to detect serum antibodies in members of a family who were infected with bancroftian filariasis and inhabitants living around them in 1990. Positive rate of ELISA was higher in these inhabitants (8.33%) than in healthy persons (2.53%), and positive ones were detected from children under age of 10. The results suggest that the detection of antifilarial antibody by using ELISA is an effective method for the surveillance of filariasis.

Adolescent↗