Randomized trial comparing endovenous laser ablation of the great saphenous vein with high ligation and stripping in patients with varicose veins: short-term results

BACKGROUND: Endovenous laser (EVL) ablation of the great saphenous vein (GSV) is thought to minimize postoperative morbidity and reduce work loss compared with high ligation and stripping (HL/S). However, the procedures have not previously been compared in a randomized trial with parallel groups where both treatments were performed in tumescent anesthesia on an out-patient basis. METHODS: Patients with varicose veins due to GSV insufficiency were randomized to either EVL (980 nm) or HL/S in tumescent anesthesia. Miniphlebectomies were also performed. Patients were examined preoperatively and at 12 days, and 1, 3, and 6 months postoperatively. Sick leave, time to normal physical activity, pain score, use of analgesics, Aberdeen score, Medical Outcomes Study Short Form-36 quality-of-life score, Venous Clinical Severity Score (VCSS), and complication rates were investigated. The total cost of the procedures, including lost wages and equipment, was calculated. Cost calculations were based on the standard fee for HL/S with the addition of laser equipment and the standard salary and productivity level in Denmark. RESULTS: A follow-up of 6 months was achieved in 121 patients (137 legs). The groups were well matched for patient and GSV characteristics. Two HL/S procedures failed, and three GSVs recanalized in the EVL group. The groups experienced similar improvement in quality-of-life scores and VCSS score at 3 months. Only one patient in the HL/S group had a major complication, a wound infection that was treated successfully with antibiotics. The HL/S and EVL groups did not differ in mean time to resume normal physical activity (7.7 vs 6.9 calendar days) and work (7.6 vs 7.0 calendar days). Postoperative pain and bruising was higher in the HL/S group, but no difference in the use of analgesics was recorded. The total cost of the procedures, including lost wages, was euro 3084 ($3948 US) in the HL/S and euro 3396 ($4347 US) in the EVL group. CONCLUSIONS: This study suggests that the short-term efficacy and safety of EVL and HL/S are similar. Except for slightly increased postoperative pain and bruising in the HL/S group, no differences were found between the two treatment modalities. The treatments were equally safe and efficient in eliminating GSV reflux, alleviating symptoms and signs of GSV varicosities, and improving quality of life. Long-term outcomes, particularly with respect to recurrence rates, shall be investigated in future studies, including the continuation of the present.     

Novel Aspects of 3D Echocardiography in Percutaneous Mitral Valve Interventions: Update 2013

The rapidly increasing importance of percutaneous treatment options for mitral valve diseases promotes the demand for reliable periprocedural guidance by transesophageal echocardiographic imaging. For several interventional mitral leaflet repair techniques real-time 3-dimensional transesophageal echocardiographic (RT3D TEE) guidance has been described to be indispensible. RT3DE TEE provides excellent insight into the mitral valve pathology, which improves procedure planning, safe guidance of device navigation and direct assessment of procedural success. For balloon mitral valvuloplasty 3D echocardiography has shown to effectively accelerate the procedure. The complexity of transcatheter mitral valve repair as well as transcatheter closure of paravalvular leakages of mitral valve prosthesis demands accurate evaluation of the target lesion and guidance of the navigation of the device catheter. All these features have recently found to be uniquely provided by three-dimensional echocardiography. The benefits of RT3D TEE led to its recommendation for percutaneous mitral valve repair procedures in current guidelines. This review of recent literature reports current applications and requirements for refinements in using 3D imaging modalities.     

PKC-theta knockout mice are protected from fat-induced insulin resistance

Insulin resistance plays a primary role in the development of type 2 diabetes and may be related to alterations in fat metabolism. Recent studies have suggested that local accumulation of fat metabolites inside skeletal muscle may activate a serine kinase cascade involving protein kinase C-theta (PKC-theta), leading to defects in insulin signaling and glucose transport in skeletal muscle. To test this hypothesis, we examined whether mice with inactivation of PKC-theta are protected from fat-induced insulin resistance in skeletal muscle. Skeletal muscle and hepatic insulin action as assessed during hyperinsulinemic-euglycemic clamps did not differ between WT and PKC-theta KO mice following saline infusion. A 5-hour lipid infusion decreased insulin-stimulated skeletal muscle glucose uptake in the WT mice that was associated with 40-50% decreases in insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and IRS-1-associated PI3K activity. In contrast, PKC-theta inactivation prevented fat-induced defects in insulin signaling and glucose transport in skeletal muscle. In conclusion, our findings demonstrate that PKC-theta is a crucial component mediating fat-induced insulin resistance in skeletal muscle and suggest that PKC-theta is a potential therapeutic target for the treatment of type 2 diabetes.     

High shear flow induces migration of adherent human platelets

Shear forces are generated in all parts of the vascular system and contribute directly and indirectly to vascular disease progression. Endothelial cells are able to adapt to flow conditions, and are known to polarize and migrate in response to shear forces. Platelets exposed to shear stress are activated and release bioactive molecules from their alpha granules. So far, platelets have been considered to be static cells that do not leave the site of tight adhesion. However, we have recently been able to demonstrate the capacity of platelets to migrate in response to stromal derived factor-1 (SDF-1). In this project, we have demonstrated that platelets accumulate in areas with a high concentration of SDF-1 under flow conditions and respond to high shear stress by cellular polarization, cytoskeletal reorganisation, and flow-directed migration. In this context, we have shown increased Wiskott-Aldrich Syndrome protein (WASP) phosphorylation and intracellular redistribution of focal adhesion kinase (FAK) under high-shear stress conditions. The effect of flow-induced platelet migration has not previously been recognized and offers a new role for platelets as mobile cells. Their migratory potential may enable platelets to cover intimal lesions and contribute to vascular repair.     

From the Cover: PNAS Plus: Comprehensive analysis of dengue virus-specific responses supports an HLA-linked protective role for CD8+ T cells

The role of CD8⁺ T cells in dengue virus infection and subsequent disease manifestations is not fully understood. According to the original antigenic sin theory, skewing of T-cell responses induced by primary infection with one serotype causes less effective response upon secondary infection with a different serotype, predisposing individuals to severe disease. A comprehensive analysis of CD8⁺ responses in the general population from the Sri Lankan hyperendemic area, involving the measurement of ex vivo IFNγ responses associated with more than 400 epitopes, challenges the original antigenic sin theory. Although skewing of responses toward primary infecting viruses was detected, this was not associated with impairment of responses either qualitatively or quantitatively. Furthermore, we demonstrate higher magnitude and more polyfunctional responses for HLA alleles associated with decreased susceptibility to severe disease, suggesting that a vigorous response by multifunctional CD8⁺ T cells is associated with protection from dengue virus disease.Dengue virus (DENV) is the etiologic agent of dengue fever (DF), the most significant mosquito-borne viral disease in humans. Disease can be caused by any of the four DENV serotypes (DENV1 to -4), which share 67–75% sequence homology with one another (1). DENV transmission occurs in more than 100 countries and is an increasing public health problem in tropical and subtropical regions (2). Demographic changes, urbanization, and international travel contribute to the expansion of geographical areas where transmission occurs, and all four DENV serotypes are now circulating in Asia, Africa, and the Americas (3, 4). Up to 100 million DENV infections occur every year (5), and severity can range from asymptomatic to an acute self-limiting febrile illness (DF). In a small proportion of patients, the disease can exacerbate and progress to dengue hemorrhagic fever (DHF) and/or dengue shock syndrome (DSS), characterized by severe vascular leakage, thrombocytopenia, and hemorrhagic manifestations (4).Although natural infection by any of the four DENV serotypes (primary infection) produces a lasting protective immunity against reinfection by the same serotype, it does not protect against infections with other serotypes (secondary infections) (6, 7). Epidemiologic studies have shown that the majority of individuals that develop DHF/DSS had been previously infected with a different serotype (8). Consequently, the development of DENV vaccines has been hampered by the potential risk of vaccine-related adverse events and the requirement to induce long-lasting protective immune responses against all four DENV serotypes simultaneously (9). The cause for the increased frequency of DHF following secondary infections has not been fully elucidated. One hypothesis is that serotype cross-reactive antibodies exacerbate disease by increasing infection of cells bearing Fcγ receptors, resulting in higher viral loads and more severe disease via this antibody-dependent enhancement (ADE) of infection (10, 11). Indeed, nonhuman primate and murine models have demonstrated that antibodies can lead to enhancement of DENV infection and disease in vivo (12–15).Another hypothesis postulates that T cells raised against the first infecting serotype dominate during a secondary heterologous infection in a phenomenon termed “original antigenic sin” (16, 17). This term was first applied to the humoral response to influenza epidemics (18) but has also been observed in CD8⁺ T-cell responses against lymphocytic choriomeningitis virus (19). This hypothesis postulates that, during secondary infection, expansion of preexisting lower avidity cross-reactive memory T cells dominate the responses over that of naïve T cells that are of higher avidity for the new DENV serotype. This expansion of low avidity T cells results in less efficient elimination of DENV-infected cells.A role for T cells in control of DENV infection is suggested by several studies that implicate HLA associations as a genetic component to variable susceptibility to DENV disease (20–26). However, it has not been addressed whether these associations might indicate a positive or detrimental role for T-cell responses. One major obstacle to the elucidation of the function of T cells is the lack of a comprehensive characterization of HLA-restricted DENV responses in the context of natural infection.Herein, we present a comprehensive analysis of functional T-cell memory against DENV and are able to correlate this with HLA alleles expressed in the very same donors. Collectively, the data suggest an HLA-linked protective role of CD8⁺ T-cell responses and do not support a causative role for CD8⁺ T cells in the induction of severe disease following secondary heterologous infection.     

Fas expression by tumor stroma is required for cancer eradication

The contribution of molecules such as perforin, IFN-γ (IFNγ), and particularly Fas ligand (FasL) by transferred CD8⁺ effector T (T_E) cells to rejection of large, established tumors is incompletely understood. Efficient attack against large tumors carrying a surrogate tumor antigen (mimicking a “passenger” mutation) by T_E cells requires action of IFNγ on tumor stroma cells to avoid selection of antigen-loss variants. Because “cancer-driving” antigens (CDAs) are rarely counterselected, IFNγ may be expected to be dispensable in elimination of cancers by targeting a CDA. Here, initial regression of large, established tumors required neither IFNγ, FasL, nor perforin by transferred CD8⁺ T_E cells targeting Simian Virus (SV) 40 large T as CDA. However, cytotoxic T_E cells lacking IFNγ or FasL could not prevent relapse despite retention of the rejection antigen by the cancer cells. Complete tumor rejection required IFNγ-regulated Fas by the tumor stroma. Therefore, T_E cells lacking IFNγ or FasL cannot prevent progression of antigenic cancer because the tumor stroma escapes destruction if its Fas expression is down-regulated.