Biomedical subjects

Y H Dong

Publications and source records attributed to Y H Dong.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Patency and tissue response related to two types of polytetrafluoroethylene-covered stents in the dog.

PURPOSE: A canine model was used to determine tissue response related to placement of two different designs of polytetrafluoroethylene (PTFE) covered stents in the peripheral vascular system. MATERIALS AND METHODS: Two types of PTFE covered stents were implanted in the iliac arteries of 15 mongrel dogs. The tissue response within and beneath these endoprostheses was studied and compared to that for control Palmaz stents with angiographic and histologic examination at 1, 3, and 6 months. RESULTS: The bare Palmaz stent endothelialized faster and with a thinner neointima than either covered stent design. Neointima formation proceeds from the ends toward the center of PTFE-covered stents regardless of design, with minimal transgraft tissue penetration. However, the pattern of neointimal response differed for the two designs and suggests that early thrombus formation at the stent-graft interface promotes neointimal development. CONCLUSION: The bare Palmaz stent showed the least amount of luminal encroachment at all time points compared with either covered stent. Regarding the covered stents, the different patterns of tissue response with the covered stents may provide insight into the design of stent-grafts for human use.

Animals↗

PubMedDate not supplied

Tissue response to covered Wallstents.

PURPOSE: To evaluate and compare the healing response related to two types of graft-covered Wallstents (WSs) and an uncovered WS in the canine iliac artery. MATERIALS AND METHODS: Eight bare mesh WSs, 10 polyethylene terephthalate interbraided WSs (PET-WSs), and six polytetrafluoroethylene covered WSs (ePTFE-WSs) were placed in the iliac arteries of 12 dogs. Arteriograms were obtained before and after implantation and at explantation. Devices were explanted at 1 month (n = 8), 3 months (n = 6), and 6 months (n = 10) and sent for histologic study. RESULTS: One ePTFE-covered stent-graft was found to be thrombosed at 3 months; the remaining 23 of 24 implants remained patent to the time of explantation. The WS and ePTFE-WS both generated a uniform myointimal cell response without inflammation. The PET-WS induced a fibrous luminal response with substantial foreign body-type inflammatory reaction around the PET fibers. Although neointima associated with the PET-WS appeared thicker than that associated with either the ePTFE-WS or the bare WS, none of the patent implants developed greater than 50% angiographic narrowing. CONCLUSION: The PET-WS induced chronic inflammation, a response not seen with either the WS or ePTFE-WS. This may explain the occurrence of pain and/or fever in human studies of arterial PET endoluminal stent-grafts. Patency for all three implants was excellent in this model.

Animals↗

PubMedDate not supplied

Residues of organochlorinated pesticides in eggs of water birds from Tai Lake in China.

The levels of organochlorine compounds in eggs of water birds from the colony on Tai Lake in China were studied. The eggs were collected in 2000 and belonged to the following species: 65 samples of black-crowned night heron (Nycticorax nycticorax), 36 samples of little egret (Egretta garzetta), 26 samples of cattle egret (Bubulcus ibis) from 13 clutches and 43 samples of Chinese pond heron (Ardeola bacchus) from 17 clutches. Dichlorodiphenyltrichloroethane (DDT) and its derivates (DDE and DDD), hexachlorocyclohexane (HCH) and its isomers (alpha-HCH, beta-HCH, gamma-HCH, delta-HCH), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, alpha-endosulfan, beta-endosulfan, and endosulfan sulfate were determined in the laboratory by gas chromatography. The data showed that DDE had the highest levels in all the samples, followed by beta-HCH. The mean levels of DDE among the water bird species were in the order as follows: black-crowned night heron (5464.26 ng/g, dry weight) > Chinese pond heron (2791.12 ng/g, dry weight) > little egret (1979.97 ng/g, dry weight) > cattle egret (660.11 ng/g, dry weight). DDT and its metabolites accounted for 90% of the total organochlorines, except that it was only 73% for cattle egret. The differences of the residue among the bird species were statistically significant and could be attributed to their variations in prey and habitat. Although the DDE burdens in Tai Lake were much lower than 8 microg/g (wet weight) which are thought to have significant adverse effects on black-crowned night herons, they would be expected to increase the risk of adverse effects on survival of chicks of herons and egrets, particularly black-crowned night heron, based on the critical value of 1 microg/g (wet weight) DDE. The burdens of HCHs in this study were higher and the cyclodienes were lower than those found elsewhere.

Animals↗