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Biomedical subjects

Alex Chen

Publications and source records attributed to Alex Chen.

6 recordsLinked to original sources
PubMed2006

Comparison of secondary prevention care after myocardial infarction and stroke.

BACKGROUND: Whether secondary prevention of atherosclerosis is performed as frequently after cerebrovascular events (stroke or transient ischemic attack) as after cardiac events (myocardial infarction or angina) is unknown. METHODS: We compared the receipt of six secondary preventive care processes among 943 persons with a prior cardiac event to that among 523 persons with a prior cerebrovascular event using a representative sample of the US population. RESULTS: The cardiac event group had higher rates for three care processes: antithrombotic medication use in the past year (83-77%, p = 0.01), ever advised to exercise more (66-52%, p < 0.001), and ever advised to eat fewer high-fat or high-cholesterol foods (70-54%, p < 0.001). CONCLUSIONS: Compared to the cardiac event group, the quality of care of the cerebrovascular event group is lower and should be improved.

Aged↗
PubMed2005

Adenovirus-mediated small-interference RNA for in vivo silencing of angiotensin AT1a receptors in mouse brain.

Because of the lack of pharmacological approaches, molecular genetic methods have been required to differentiate between angiotensin type 1(AT1) receptor subtypes AT1a and AT1b. RNA interference is a new tool for the study of gene function, producing specific downregulation of protein expression. In this study, we used the small hairpin RNA (shRNA) cassette method to screen target sites for selectively silencing AT1a or AT1b receptor subtypes in cultured Neuro-2a cells using real-time RT-PCR. For in vivo functional studies, we used C57BL mice with arterial telemetric probes and computerized licking monitors to test the effect of adenovirus carrying the DNA sequence coding AT1a shRNA (Ad-AT1a-shRNA). Ad-AT1a-shRNA was injected into the lateral ventricle (intracerebroventricular) or the brain stem nucleus tractus solitaries/dorsal vagal nucleus (NTS/DVN) with measurement of water intake, blood pressure (BP), and heart rate (HR) for up to 20 days after injection. Tissue culture studies verified the specificity and the efficiency of the constructs. In animal studies, beta-galactosidase staining and Ang receptor binding assays showed expression of shRNA and downregulation of Ang AT1 receptors in the subfornical organ and NTS/DVN by >70%. Intracerebroventricular injection of Ad-AT1a-shRNA increased water intake with no effect on BP or HR. In contrast, microinjection of Ad-AT1a-shRNA into NTS/DVN caused a decrease in BP with no effect on HR or water intake. Results demonstrate the use of the RNA interference method in site-directed silencing of gene expression and provide a method for the in vivo study of Ang AT1 receptor function.

Adenoviridae↗
PubMed2005

Intraoperative (125)I Vicryl mesh brachytherapy after sublobar resection for high-risk stage I non-small cell lung cancer.

PURPOSE: To assess the feasibility and outcomes of (125)I Vicryl mesh brachytherapy after sublobar resection in stage I non small cell lung cancer (NSCLC) patients with poor pulmonary function. METHODS AND MATERIALS: Between January 1997 and July 2004, patients with poor cardiopulmonary reserve who had stage IA and IB (T1-2 N0 M0) NSCLC and a forced expiratory volume in 1s (FEV(1)) of > micro=0.6L were considered for limited surgical resection either by an open or video-assisted thoracoscopic procedure and for a subsequent (125)I Vicryl mesh brachytherapy implant. Mediastinal and hilar lymph node staging was performed routinely in all patients. After clear margins were obtained grossly and on frozen section, a single-plane (125)I implant was designed to encompass a plane consisting of the staple line and a 2-cm margin of surrounding visceral pleura. The implant was introduced through the surgical incision and sutured to the visceral pleura. A prescribed dose of 100-120 y was delivered to a volume within 0.5 cm rom the plane of the implant. Follow-up orthogonal films or CTs were obtained for dosimetric analysis. Kaplan-Meier analyses were used to estimate the local control, locoregional control, and overall survival rates. RESULTS: Of the 110 patients, 65 had stage IA and 45 had stage IB NSCLC. The mean preoperative FEV(1) was 47% of the predicted volume. With a median follow-up of 11 months (range 1-68 months), there were four recurrences within the radiation volume. The estimated 5-year local (in-field) control, locoregional control, and overall survival rates were 90%, 61%, and 18%, respectively. CONCLUSION: Vicryl mesh brachytherapy after sublobar resection for high-risk stage I NSCLC patients is a feasible procedure, which results in an excellent local (in-field) control rate.

Aged↗
PubMed2004

Gene expression of early hypertrophic scar tissue screened by means of cDNA microarrays.

BACKGROUND: Hypertrophic scar is an excessive healing response that often follows thermal injury. The most outstanding morphologic change is the overdeposition of collagen, which is caused by imbalance between synthesis and metabolism of collagen. Previous studies also found that transforming growth factor-beta was the key factor controlling scar formation. However, neither anti-transforming growth factor-beta nor other methods could completely control scar formation and contraction. This fact suggests a multifactorial cause. Fortunately, cDNA microarray throws light on the general alteration at the gene level, and thus could allow us to find some new clues for understanding scar formation and contraction. METHODS: In this article, we report the results obtained from the scanning of gene expression of hypertrophic scar by means of cDNA microarray. Five cases of early human postburn hypertrophic scars were selected. Total tissue RNA was extracted from each hypertrophic scar sample and the corresponding uninjured region skin tissue; mRNA was further purified by Oligotex and then was reversely transcribed to cDNAs with the incorporation of fluorescent dUTP to prepare the hybridization probes. The mixed probes were hybridized to the cDNA microarray containing 4,096 genes on a type of chemical material-coated glass slide. After high-stringent washing, the hybridized slides were scanned for fluorescent signal detection. Then, the expression and distribution of cytoskeletal genes such as alpha-smooth muscle actin (alpha-SMA) gene; fibroblast tropomyosin TM30(pl) gene; vimentin gene; profilin gene; and BM40 gene of hypertrophic scar at 3, 6, 9, and 12 months age were further quantitatively studied by in situ hybridization or immunohistochemistry. RESULTS: Our data indicated that there were 94 genes overexpressed and 3 genes down-regulated in early postburn hypertrophic scar. These altered genes were related to proto-oncogenes, apoptosis, immune regulatory genes, cytoskeletal elements, metabolism, and so forth. We also found that the detected cytoskeletal gene expression was much more intense at all time points than the control group. Consistent with clinical observation, cytoskeletal genes reached a peak at an early stage and gradually decreased. CONCLUSION: Our study implied that multiple genes are involved in scar formation and contraction. Interferon is an autosecreted cytokine that might be responsible for self-control of overgrowth of cells in wounds. The early period of hypertrophic scar formation might be a good time for preventing overgrowth and contraction of hypertrophic scar by gene therapy.

Actins↗