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Biomedical subjects

X M Yang

Publications and source records attributed to X M Yang.

103 records · Page 6Linked to original sources

Percutaneous endovascular stenting: development, investigation and application.

Percutaneous endovascular stenting (PES), a new and alternative approach of interventional radiologic techniques, has encouraging potentials for management of vascular obstructive diseases. The most important role of PES is to prevent the risk of abrupt closure and to reduce the rate of early and late post-angioplasty restenosis (PARS) of PTA. Because of different working mechanisms, various stents show different advantages and disadvantages. Specific indications of PES are: (1) further compensation for failed PTA, (2) management of complications due to PTA and (3) primary treatment of vascular obstructive diseases. Based on a preliminary comparison with atherectomy, laser angioplasty and PTA, PES seems to provide an advantage for long-term patency of large caliber vessels such as iliac arteries, while more significant problems still exist in PES with small caliber vessels such as femoral-popliteal and coronary arteries. Further comparative clinical research is required to establish the utility of PES among other intraluminal techniques of vascular interventions.

Animals↗

Differential gene expression between visceral and subcutaneous fat depots.

Abdominal obesity has been linked to the development of insulin resistance and Type 2 diabetes mellitus (DM2). By surgical removal of visceral fat (VF) in a variety of rodent models, we prevented insulin resistance and glucose intolerance, establishing a cause-effect relationship between VF and the metabolic syndrome. To characterize the biological differences between visceral and peripheral fat depots, we obtained perirenal visceral (VF) and subcutaneous (SC) fat from 5 young rats. We extracted mRNA from the fat tissue and performed gene array hybridization using Affymetrix technology with a platform containing 9 000 genes. Out of the 1 660 genes that were expressed in fat tissue, 297 (17.9 %) genes show a two-fold or higher difference in their expression between the two tissues. We present the 20 genes whose expression is higher in VF fat (by 3 - 7 fold) and the 20 genes whose expression is higher in SC fat (by 3 - 150 fold), many of which are predominantly involved in glucose homeostasis, insulin action, and lipid metabolism. We confirmed the findings of gene array expression and quantified the changes in expression in VF of genes involved in insulin resistance (PPARgamma leptin) and its syndrome (angiotensinogen and plasminogen activating inhibitor-1, PAI-1) by real-time PCR (qRT-PCR) technology. Finally, we demonstrated increased expression of resistin in VF by around 12-fold and adiponectin by around 4-fold, peptides that were not part of the gene expression platform. These results indicate that visceral fat and subcutaneous fat are biologically distinct.

Adipocytes↗

Retroperfusion and balloon support to improve coronary revascularization.

Coronary venous retroperfusion and Intra-Aortic Balloon Pump (IABP) support are methods currently utilized to reduce ischemic damage prior to revascularization of acutely ischemic myocardium. This study was undertaken to determine whether combining coronary venous retroperfusion using Pressure Controlled Intermittent Coronary Sinus Occlusion (PICSO) with the IABP would result in improved salvage of ischemic myocardium. In 40 adult pigs, the second and third diagonal vessels were occluded with snares for 1 1/2 hours followed by 1/2 hours of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary occlusion prior to arrest, 10 pigs received the IABP, 10 had PICSO, 10 had PICSO+IABP, while 10 had no intervention (Unmodified). Ischemic damage was assessed by echocardiographic wall motion scores, myocardial pH, and the area of necrosis/area of risk using histochemical staining. Both PICSO and the IABP alone significantly reduced ischemic damage. However, the best wall motion scores, highest pH, and least necrosis was seen in the IABP+PICSO group. We conclude that the combination of coronary venous retroperfusion using PICSO and the IABP results in the most optimal recovery of acutely ischemic myocardium during emergent surgical revascularization.

Animals↗