Structural optimization of degradable polymer vascular stents based on surrogate models.

The clinical performance of biodegradable polymer stents implanted in blood vessels is affected by uneven degradation. Stress distribution plays an important role in polymer degradation, and local stress concentration leads to the premature fracture of stents. Numerical simulations combined with experimental validation can accurately describe the degradation process and perform structural optimization.

Symmetrical structure design of PLGA Biodegradable sinus stents and structure optimization based on surrogate models.

This study aims to enhance the degradation uniformity of PLGA sinus stents to minimize fracture risk caused by stress corrosion. Symmetric stent structures were introduced and compared to sinusoidal structure in terms of stress and degradation uniformity during implantation and degradation processes. Three surrogate models were employed to optimize the honeycomb-like structure.

Effect of ureteral stent length and implantation position on migration after implantation.

Background: Ureteral obstruction is a urinary system disease that causes urinary retention, renal injury, renal colic, and infection. Ureteral stents are often used for conservative treatment in clinics, and their migration usually results in ureteral stent failure. The migrations include proximal migration to the kidney side and distal migration to the bladder side, but the biomechanism of stent migration is still unknown.

The differences between surface degradation and bulk degradation of FEM on the prediction of the degradation time for poly (lactic-co-glycolic acid) stent.

The degradation time is a crucial factor in evaluating the performance of poly (lactic-co-glycolic acid) (PLGA) stents. Bulk degradation mode was commonly used to analyze the stent degradation behavior by finite element approach. However, the PLGA stents may present surface degradation more than bulk degradation under certain conditions, which will greatly affect the degradation time after implantation.

Effect of strain on degradation behaviors of WE43, Fe and Zn wires.

The biodegradable metallic devices undergo stress/strain-induced corrosion when they are used for load-bearing applications. The stress/strain induced-corrosion behavior causes differences in corrosion rate, corrosion morphology, strain distribution and mechanical performance of the devices. One representative example is the biodegradable stent.

Effect of stress on corrosion of high-purity magnesium in vitro and in vivo.

Magnesium-based implants are subjected to complicated stresses during implantation in the human body. The stress effects on corrosion of magnesium (Mg) in vitro were investigated in previous studies, whereas in this study, the corrosion behaviors of high-purity (HP) Mg under stress were comparatively studied in vitro in Hank's solution and in vivo in the subcutaneous environment of rats. Loading devices were designed to apply compressive stress (15.

A quantitative study on magnesium alloy stent biodegradation.

Insufficient scaffolding time in the process of rapid corrosion is the main problem of magnesium alloy stent (MAS). Finite element method had been used to investigate corrosion of MAS. However, related researches mostly described all elements suffered corrosion in view of one-dimensional corrosion.

Effects of different fluid shear stress patterns on the in vitro degradation of poly(lactide-co-glycolide) acid membranes.

The applications of poly (lactide-co-glycolide) acid (PLGA) for coating or fabricating polymeric biodegradable stents (BDSs) have drawn more attention. The fluid shear stress has been proved to affect the in vitro degradation process of PLGA membranes. During the maintenance, BDSs could be suffered different patterns of fluid shear stress, but the effect of these different patterns on the whole degradation process is unclear.

The complex fluctuations of probabilistic Boolean networks.

Probabilistic Boolean networks (PBNs) are extensions of Boolean networks (BNs), and both have been widely used to model biological systems. In this paper, we study the long-range correlations of PBNs based on their corresponding Markov chains. PBN states are quantified by the deviation of their steady-state distributions.

Pulmonary oligemia maneuver can alleviate pulmonary artery injury during pulmonary thromboendarterectomy procedure.

Background: Pulmonary thromboendarterectomy (PTE) has evolved as a treatment of choice for chronic thromboembolic pulmonary hypertension (CTEPH). This study aimed to characterize if pulmonary oligemia maneuver (POM) can alleviate pulmonary artery injury during PTE procedure.

Methods: A total of 112 cases of CTEPH admitted to Beijing Anzhen Hospital from March 2002 to August 2011 received PTE procedure.

[Obstructive sleep apnea-hypopnea syndrome in patients with pulmonary thromboembolism: clinical features and management].

Objective: To describe the clinical features of obstructive sleep apnea-hypopnea syndrome (OSAHS) in hospitalized pulmonary thromboembolism (PTE) patients, and to explore its impact on the severity of disease and management among patients with PTE.

Methods: Demographic and clinical characteristics of 28 PTE patients complicated with OSAHS admitted to this hospital from January 2002 to December 2010 were analyzed. A total of 30 PTE patients without OSAHS served as a control group.

Surgical treatment of pulmonary artery sarcoma.

Objective: The study objectives were to characterize the prognostic perspectives of pulmonary artery sarcoma and to investigate the effect of distal embolectomy on the prognosis of surgical treatment of pulmonary artery sarcoma.

Methods: Nine patients with pulmonary artery sarcoma were surgically treated at Anzhen Hospital, and the data were retrospectively reviewed. Five patients underwent only pulmonary artery sarcoma resection, and 4 patients underwent both pulmonary artery sarcoma resection and distal embolectomy.

[Clinical analysis of 62 cases of chronic thromboembolic pulmonary hypertension treated with pulmonary thromboendarterectomy without early and late deaths].

Objective: To retrospectively evaluate the effects of pulmonary thromboendarterectomy (PTE) on chronic thromboembolic pulmonary hypertension (CTEPH).

Methods: Sixty-two cases of CTEPH operated with PTE from October 2002 to September 2008 at Anzhen Hospital were retrospectively reviewed and were assigned into either proximal CTEPH group (n = 46) or distal CTEPH group (n = 16).

Result: No early death was reported.

[Expression of various matrix metalloproteinases in mice with hyperoxia-induced acute lung injury].

Objective: To investigate the role of matrix metalloproteinases (MMPs) and extracellular matrix metalloproteinase inducer (EMMPRIN) in the pathogenesis of acute lung injury induced by hyperoxia.

Methods: Fifty four mice were exposed in sealed cages to >98% oxygen (for 24-72 hours), and another 18 mice to room air. The severity of lung injury was assessed, and the expression of mRNA and protein of MMP-2, MMP-9 and EMMPRIN in lung tissue, after exposure for 24, 48 and 72 hours of hyperoxia were studied by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry.