Stents: Biomechanics,Biomaterials, and Insights from Computational Modeling

Coronary stents have revolutionized the treatment of coronary artery disease. Improvement in clinical outcomes requires detailed evaluation of the performance of stent biomechanics and the effectiveness as well as safety of biomaterials aiming at optimization of endovascular devices. Stents need to harmonize the hemodynamic environment and promote beneficial vessel healing processes with decreased thrombogenicity. Stent design variables and expansion properties are critical for vessel scaffolding. Drug-elution from stents, can help inhibit in-stent restenosis, but adds further complexity as drug release kinetics and coating formulations can dominate tissue responses. Biodegradable and bioabsorbable stents go one step further providing complete absorption over time governed by corrosion and erosion mechanisms. The advances in computing power and computational methods have enabled the application of numerical simulations and the in silico evaluation of the performance of stent devices made up of complex alloys and bioerodible materials in a range of dimensions and designs and with the capacity to retain and elute bioactive agents. This review presents the current knowledge on stent biomechanics, stent fatigue as well as drug release and mechanisms governing biodegradability focusing on the insights from computational modeling approaches.     

Predictors of endothelial dysfunction in young women with polycystic ovary syndrome

CONTEXT: Women with polycystic ovary syndrome (PCOS) may be at increased risk for cardiovascular disease. Endothelial dysfunction is an early marker of atherosclerosis. OBJECTIVES: The objectives of this study were to 1) compare endothelial function in young women with PCOS and regularly menstruating control women, and 2) to identify the determinants of endothelial function and investigate its relationship with body mass index in women with PCOS. DESIGN: This was a cross-sectional study. SETTING: This study was conducted at a tertiary cardiovascular research center. PATIENTS: Sixty-two young women with PCOS (mean age, 22.7 yr) and 17 control women, matched as a group for age and body mass index, were studied. Twenty-three women with PCOS were lean, 21 were overweight, and 18 were obese. MAIN OUTCOME MEASURES: Endothelium-dependent and -independent vascular function was assessed by measuring flow-mediated dilation (FMD) and nitrate-mediated dilation in the brachial artery (diameter change during hand hyperemia and after sublingual glyceryl trinitrate administration, respectively). RESULTS: FMD and nitrate-mediated dilation were significantly lower in PCOS than in control women (reduced by approximately 50 and 25%, respectively; both P < 0.0005). Insulin resistance, total testosterone, and total cholesterol were independent predictors of FMD, accounting for 21, 10, and 9% of the variance, respectively (P < 0.005 for all). A trend of deterioration in FMD from lean to overweight and obese PCOS women was observed, but differences among groups were not statistically significant. CONCLUSIONS: Women with PCOS have significant endothelial dysfunction at an early age (i.e. early 20s), and largely independent of obesity. This suggests that women with PCOS are at increased risk for early onset cardiovascular disease and may gain particular benefit from measures to improve endothelial function.     

Return to Play Considerations After Patellar Instability

Purpose of ReviewTo discuss the treatment options and rehabilitation protocols after non-operative and operative treatment of patellar instability, and to discuss expected return to play outcomes and functional performance with non-operative and operative treatment of patellar instability.Recent FindingsA criterion-based program assessing range of motion, joint effusion, strength, neuromuscular control, proprioception, agility, and power are critical measures to assess when rehabilitating this population. A series of functional tests including quadriceps strength testing, single-limb hop testing, lateral step-down test, the side hop test, the lateral leap and catch test, the Y-balance test, and the depth jump should be considered when determining an athlete’s return to sport clearance. These objective measures combined with psychological readiness and a comprehensive understanding of the sports-specific tasks required for participation should be considered when evaluating an athlete’s ability to safely and successfully return to sport.SummaryWe discuss rehabilitation management when working with non-operative and operative management of patellar instability and provide considerations for clinicians working with these athletes to facilitate safe return to sport.     

Influenza Virus Infection during Pregnancy as a Trigger of Acute and Chronic Complications

Influenza A virus (IAV) infection during pregnancy disrupts maternal and fetal health through biological mechanisms, which are to date poorly characterised. During pregnancy, the viral clearance mechanisms from the lung are sub-optimal and involve hyperactive innate and adaptive immune responses that generate wide-spread inflammation. Pregnancy-related adaptations of the immune and the cardiovascular systems appear to result in delayed recovery post-viral infection, which in turn promotes a prolonged inflammatory phenotype, increasing disease severity, and causing maternal and fetal health problems. This has immediate and long-term consequences for the mother and fetus, with complications including acute cardiopulmonary distress syndrome in the mother that lead to perinatal complications such as intrauterine growth restriction (IUGR), and birth defects; cleft lip, cleft palate, neural tube defects and congenital heart defects. In addition, an increased risk of long-term neurological disorders including schizophrenia in the offspring is reported. In this review we discuss the pathophysiology of IAV infection during pregnancy and its striking similarity to other well-established complications of pregnancy such as preeclampsia. We discuss general features of vascular disease with a focus on vascular inflammation and define the “Vascular Storm” that is triggered by influenza infection during pregnancy, as a pivotal disease mechanism for short and long term cardiovascular complications.     

Prognostic factors for survival in invasive squamous cell vulvar carcinoma: a univariate analysis.

The charts of 50 women with invasive squamous cell vulvar carcinoma were reviewed retrospectively, and pathologic, medical and life style factors were analyzed for their possible influence on survival using the Cox regression univariate model. The median age of the cohort was 73.5 years. The patient distribution according to stage was as follows: stage I: 17; stage II: 16; stage III: 12, and stage IVa: 5 patients. The median follow-up was 61 months. The univariate analysis revealed that the overall survival was decreased by age > or = 73.5 years (p = 0.0185), advanced stage (p = 0.0026), grade III differentiation (p < 0.0001), ulcerative type of the tumor (p = 0.0055), tumor diameter >40 mm (p = 0.0053), obesity (p = 0.011), smoking (p = 0.0177), diabetes (p = 0.0122) and hypertension (p = 0.044), but not with clitoral involvement.     

Akt in the pathogenesis of COPD

In this review we consider the therapeutic potential of targeting Akt for the treatment of COPD. Akt is a serine/threonine protein kinase that functions as a signaling intermediate linked to multiple signaling programs involved in survival, inflammation, and growth. Akt is closely associated with key membrane-bound receptors and represents a convergent integration point for multiple stimuli implicated in COPD pathogenesis. Persistent activation of Akt secondary to somatic mutations in regulatory oncogenes, such as PTEN, may explain why inflammation in COPD does not resolve when smoking is ceased. Akt is also implicated in the systemic manifestations of COPD such as skeletal muscle wasting and metabolic disturbances. Furthermore, targeting Akt may provide a useful means of limiting the severity and duration of disease exacerbations in COPD. As such, Akt represents a particularly attractive therapeutic target for the treatment of COPD. Interestingly, current knowledge suggests that both inhibitors and activators of Akt may be useful for treating different clinical subpopulations of COPD patients.     

Unilateral emphysematous pyelonephritis.

A case of unilateral emphysematous pyelonephritis is presented in a patient with uncontrolled diabetes mellitus. The diagnosis was established from the presence of gas in the renal parenchyma, the pelvicalyceal system and the ureter. The patient was treated with a prolonged course of antibiotics and the function of the left kidney returned to normal.     

Abdominal Takayasu's arteritis: imaging with color duplex sonography

Takayasu's arteritis is a inflammatory process of unknown etiology affecting mainly the thoracic and abdominal aorta and producing steno-occlusive findings of various degrees in different sites. We present a case of Takayasu's disease in a young woman, studied by color duplex sonography and verified by angiography. Received 22 April 1996; Revision received 4 September 1996; Accepted 15 July 1997