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Biomedical subjects

Q S Chen

Publications and source records attributed to Q S Chen.

24 records · Page 2Linked to original sources
PubMed1984

A simplified new method for the identification of arboviruses: virus detection using enzyme immunoassay on cultured cells.

A simple new method is reported for the identification of arbovirus isolates and the titration of arboviruses. Horseradish peroxidase conjugated Staphylococcus aureus protein A was used for the indirect staining of virus antigens grown in an Aedes albopictus cell line, C6/36 cells. Thirty-five isolates from Culex tritaeniorhynchus mosquitoes were examined by this method and 20 of these were identified as Japanese encephalitis virus (JEV). These results were confirmed by immunofluorescent assay and plaque neutralization test. Comparative titration of JEV, Murray Valley encephalitis (MVE) and Kunjin viruses showed that this method was as sensitive as the chick embryo plaque assay. Specific enzymatic reactions on these virus-infected cells began to appear before day 3 and reached the end-point on day 5 post-infection of C6/36 cells, whereas the cytopathic effect (CPE) appeared about 2 days later than the positive enzymatic reactions. Fixation with 10% formalin for 0.5-8 h did not damage the positive reaction in infected cells and did not increase the background colour of uninfected cells.

Animals↗
PubMedDate not supplied

Effects of serotonin-receptor blockade on angioplasty-induced vasospasm in an atherosclerotic rabbit model.

Vasospasm occurs both in patients and animal models after angioplasty and may be associated with early closure of the dilated vessel. To investigate the mechanism of angioplasty-induced vasospasm, the effect of serotonin-receptor blockade with two serotonin2 (S2) antagonists, LY53857 and sergolexole, was examined in rabbits with focal femoral artery atherosclerosis. In preliminary studies, local infusion of 1-100 micrograms serotonin caused significant femoral artery vasoconstriction (p less than 0.05) in both normal and atherosclerotic rabbits. There was no significant difference in the degree of vasoconstriction induced by equal doses of serotonin in normal and atherosclerotic animals. Infusion of 10 micrograms serotonin produced a 23 +/- 5% decrease in luminal diameter in atherosclerotic femoral arteries. This was blocked by pretreatment with both S2 inhibitors given separately in different animals before serotonin infusion (p less than 0.002). In contrast, LY53857 (sergolexole was not tested) had no significant effect on phenylephrine-induced vasoconstriction, confirming its specificity as an S2-receptor antagonist. Balloon angioplasty of atherosclerotic vessels caused a significant increase in vessel diameter at the angioplasty site (45% increase from baseline diameter, p less than 0.05). This was associated with significant luminal narrowing both proximal (21% reduction from baseline, p less than 0.05) and distal (17% reduction from baseline, p less than 0.03) to the angioplasty site. These proximal and distal changes are most likely due to vasospasm, as there was no histological evidence of thrombus or dissection at these sites to explain the luminal narrowing. Pretreatment of animals with 10 mg LY53857 or 20 mg sergolexole blocked the proximal vasospasm (2.6 +/- 0.4 before versus 2.2 +/- 0.1mm after angioplasty for LY53857, 2.1 +/- 0.4 before versus 2.1 +/- 0.4 mm after angioplasty for sergolexole; p = NS). Treatment with 20 mg LY53857 inhibited both proximal (2.3 +/- 0.1 before versus 2.2 +/- 0.2 mm after angioplasty, p = NS) and distal (1.7 +/- 0.1 before versus 1.6 +/- 0.2 mm after angioplasty, p = NS) vasospasm after angioplasty. Proximal (2.3 +/- 0.5 before versus 2.5 +/- 0.3 mm after) and distal (1.7 +/- 0.2 before versus 1.7 +/- 0.4 mm after) vasospasm was also prevented by pretreatment with 40 mg sergolexole.(ABSTRACT TRUNCATED AT 400 WORDS)

Angioplasty, Balloon↗
PubMedDate not supplied

Hepatitis B vaccination among Vietnamese-American children in a Boston community clinic.

PURPOSE: This manuscript describes one community health center s efforts to provide catch-up immunization for hepatitis B for Vietnamese Americans aged 7 to 17. METHODS: A chart review of 151 Vietnamese-American children seen at the health center was conducted in Spring, 2001. Letters were sent to notify parents of their children's immunization status. One month later, the investigators attempted to contact the parents by phone. The interviews were done to conduct a survey about hepatitis B virus (HBV), and to encourage parents whose children needed further follow-up to do so. PRINCIPAL FINDINGS: Chart review revealed that 2% (n=3) of the patients were chronically infected with HBV, and 28% (n=42) were known to be already immune due to prior exposure. Thirteen patients had either moved or were obtaining care elsewhere. Of those needing vaccination (n=93), 76 (82%) completed the series of three vaccines. Of the remaining 17 patients needing further follow-up, 9 were vaccinated in the community clinic, for a 91% vaccination rate (85 of 93). For this survey, a 63% survey response rate was achieved among the patients' parents (55 of 88 eligible households). Of parents reporting that their children had a hepatitis B vaccination (HepB), study investigators were unable to confirm 25% by chart review. Although letters were sent regarding their children's HBV status, only 71% reported having heard of HBV, and 60% reported having heard of HepB vaccine. The children's receipt the HepB vaccine was not significantly associated with the parents' having heard of HBV or HepB vaccination, the parents' length of time in the United States, their health insurance status, or their level of education. CONCLUSIONS: These findings suggest that parents need more education about HBV, and that the information they provide about their children's vaccination status may not be reliable.

Adolescent↗