Biomedical subjects

Tsun-Mei Lin

Publications and source records attributed to Tsun-Mei Lin.

7 recordsLinked to original sources

PubMed2003

Association of CD14 promoter gene polymorphism and Chlamydia pneumoniae infection.

Recent studies have suggested that Chlamydia pneumoniae infection is an important factor in the development of atherosclerosis. The C(-260)-->T polymorphism in the CD14 promoter gene has been reported to regulate the density of CD14 expression on monocytes for the activation of monocytes to secrete inflammatory cytokines by lipopolysaccharide. We investigated this genetic marker and its association with C. pneumoniae infection. Among 315 healthy subjects, the distribution of the C(-260)-->T polymorphism in the CD14 promoter gene was 14.9% for the CC genotype, 54.3% for the CT genotype, and 30.8% for the TT genotype. Among subjects with the 3 CD14 genotypes, 59.5%, 64.9%, and 78.3%, respectively, were seropositive for C. pneumoniae. With multiple logistic regression analysis, the odds ratio of C. pneumoniae infection was 2.08 for CD14 TT genotype (95% confidence interval, 1.18-3.69; P=.016). A significant association between the CD14 TT genotype and C. pneumoniae infection was found.

Adult↗

PubMed2003

Cell-to-cell contact of human monocytes with infected arterial smooth-muscle cells enhances growth of Chlamydia pneumoniae.

Chlamydia pneumoniae can infect arterial cells. It has been shown that coculture of human monocytes (U937) and endothelial cells promotes infection of C. pneumoniae in endothelial cells and that the enhancement was mediated by a soluble factor (insulin-like growth factor 2) secreted by monocytes. In this study, it is shown that coculture of monocytes with C. pneumoniae enhances infection of C. pneumoniae in arterial smooth-muscle cells 5.3-fold at a monocyte-to-smooth-muscle cell ratio of 5. However, unlike endothelial cells, no enhancement was observed if monocytes were placed in cell culture inserts or if conditioned medium from monocyte cultures was used, which suggests that cell-to-cell contact is critical. The addition of mannose 6-phosphate or octyl glucoside, a nonionic detergent containing a sugar group, to cocultures inhibited the enhancement. These findings suggest that the monocyte-smooth-muscle cell interaction may be mediated by mannose 6-phosphate receptors present on monocytes.

Arteries↗

PubMed2003

4G/5G promoter polymorphism of plasminogen activator inhibitor-1, lipid profiles, and ischemic stroke.

The 4G allele of common 4G/5G polymorphism in the promoter of the plasminogen activator inhibitor-1 (PAI-1) gene is associated with increased PAI-1 transcription and has been proposed as a candidate genetic risk factor for thrombotic diseases. We investigated the relationship between this polymorphism and lipid profiles and stroke risk. One hundred patients with ischemic stroke and 150 age- and sex-matched control subjects were enrolled. PAI-1 genotype was determined with the use of polymerase chain reaction and restriction-length analysis. Genotype distribution in the stroke group was 40% 4G/4G, 46% 4G/5G, and 14% 5G/5G; in the control group it was 38.7% 4G/4G, 45.3% 4G/5G, and 16% 5G/5G. The allele and genotype frequencies of 4G/5G polymorphism were not different between the stroke and control groups. Control subjects who were homozygous for the 4G allele had significantly lower high-density lipoprotein (HDL) cholesterol levels than did those carrying the 5G allele (51.2 +/- 11.8 vs 58.4 +/- 15.8 mg/dL; P =.002). In the control group, regression analysis revealed a significant contribution of 4G/4G genotype to increased triglyceride (P =.042) and to decreased HDL cholesterol (P <.001) levels. Our findings suggest that PAI-1 4G/5G promoter polymorphism alone is not associated with ischemic stroke. However, this polymorphism influences lipid levels, and the underlying mechanism must be determined.

Aged↗

PubMed2002

Foam cell formation inhibits growth of Chlamydia pneumoniae but does not attenuate Chlamydia pneumoniae-induced secretion of proinflammatory cytokines.

BACKGROUND: It has not yet been determined whether lipid-loaded macrophages (foam cells), a major cellular component of atherosclerotic lesions, have the capacity to support growth of Chlamydia pneumoniae and be activated to secrete proinflammatory cytokines in response to C pneumoniae infection. METHODS AND RESULTS: Lipid loading of RAW 264.7 cells and mouse peritoneal macrophages with either oxidized or acetylated LDL significantly inhibits the growth of C pneumoniae. Modified forms of LDL are not directly toxic to C pneumoniae and do not inhibit either the initial binding or internalization of C pneumoniae by macrophages. Lipid loading does not reduce infection of macrophages with Chlamydia trachomatis. Treatment of lipid-loaded macrophages with live, heat-killed, or UV-inactivated C pneumoniae stimulates secretion of cytokines. C pneumoniae also induces expression of the mRNA for tumor necrosis factor-alpha in foam cells despite inhibition of nuclear factor-kappaB binding to DNA by prior treatment with oxidized LDL. CONCLUSIONS: Foam cell formation is not conducive to growth of C pneumoniae but does not inhibit the C pneumoniae-induced secretion of proinflammatory cytokines.

Animals↗

PubMed2002

Decrease of fibrinolytic activity in human endothelial cells by arsenite.

Blackfoot disease (BFD) is an endemic peripheral vascular occlusive disease that occurred in the southwest coast of Taiwan. It is believed that arsenic in the drinking water from artesian wells plays an important role in the development of the disease. We have previously shown that BFD patients had significant lower tissue-type plasminogen activator (t-PA) antigen level and higher plasminogen activator inhibitor, Type 1 (PAI-1) antigen level than normal controls. The purpose of this study was to investigate the effects of arsenite on the fibrinolytic and anticoagulant activities of cultured macrovascular and microvascular endothelial cells. Incubation of human microvascular endothelial cells (HMEC-1), but not human umbilical vein endothelial cells (HUVECs), with arsenite caused a decrease of t-PA mRNA level, a rise of both PAI-1 mRNA level and PAI activity. Arsenite could also inhibit the thrombomodulin (TM) mRNA expression and reduce the TM antigen level in HMEC-1. In conclusion, arsenite had a greater effect on HMEC-1 as compared to HUVECs in lowering the fibrinolytic activity and may be responsible for the reduced capacity of fibrinolysis associated with BFD.

Arsenites↗

PubMed2002

Mannose-receptor positive and negative mouse macrophages differ in their susceptibility to infection by Chlamydia species.

It has been shown that N-linked high mannose type oligosaccharides competitively inhibits attachment to and infectivity of chlamydiae in HeLa cells. To further study whether mannose moieties are involved in the infectivity of chlamydiae, the susceptibility of mannose-receptor negative J774A and positive J774E mouse macrophages to Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae was evaluated. C. trachomatis infected mannose-receptor positive cells better than mannose-receptor negative cells. C. psittaci infected both mannose-receptor negative and positive cells equally well, while C. pneumoniae infected mannose-receptor negative cells better than mannose-receptor positive cells. Further studies using this system may provide insight into the role of mannose-receptor in attachment, entry and survival of chlamydiae in macrophages.

Animals↗

PubMed2002

Failure to detect human papillomavirus DNA in malignant epithelial neoplasms of conjunctiva by polymerase chain reaction.

To elucidate the putative role of human papillomavirus (HPV) infection in the etiology of conjunctival tumors, 44 formalin-fixed, paraffin-embedded specimens of conjunctival tumors (24 patients with papillomas and 20 patients with dysplastic and/or malignant tumors) were screened for HPV infection using 4 different polymerase chain reactions (PCRs). Of the 24 samples of papilloma, 14 (58%) displayed positive results by applying nested PCR using primer sets of HPV consensus L1 region. HPV type 6 or 11 was detected in 9 cases of papilloma by type-specific primer sets, but none of them were positive for HPV type 16 or 18. However, by using the highly sensitive PCR technique, we failed to demonstrate the HPV DNA of HPV types 6, 11, 16, and 18 in any of the 20 malignant epithelial tumors of conjunctiva. We conclude that HPV-6 or HPV-11 is present in a substantial percentage of conjunctival papillomas, which is in accordance with findings of previously reported studies. In contrast, malignant conjunctival carcinomas are not associated with HPV infection; other pathogenic mechanisms, such as UV light, probably are more important in the cause of these malignant lesions.

Carcinoma, Squamous Cell↗