Molecular pathogenesis of human parechovirus 1 infection

The Parechoviruses (HPEV) belong to the family Picornaviridae of positive-stranded RNA viruses. Although the parechovirus genome shares the general properties of other picornaviruses, the genus has several unique features when compared to other family members. We found that HPEV1 attaches to αv integrins on the cell surface and is internalized through the clathrin-mediated endocytic pathway. During he course of the infection, the Golgi was found to disintegrate and the ER membranes to swell and loose their ribosomes. The replication of HPEV1 was found to take place on small clusters of vesicles which contained the trans-Golgi marker GalT as well as the viral non-structural 2C protein. 2C was additionally found on stretches of modified ER-membranes, seemingly not involved in RNA replication. The viral non-structural 2A and 2C proteins were studied in further detail and were found to display several interesting features. The 2A protein was found to be a RNA-binding protein that preferably binds to positive sense 3 UTR RNA. It was found to bind also duplex RNA containing 3 UTR(+)-3 UTR(-), but not other dsRNA molecules studied. Mutagenesis revealed that the N-terminal basic-rich region as well as the C-terminus, are important for RNA-binding. The 2C protein on the other hand, was found to have both ATP-diphosphohydrolase and AMP kinase activities. Neither dATP nor other NTP:s were suitable substrates. Furthermore, we found that as a result of theses activities the protein is autophosphorylated. The intracellular changes brought about by the individual HPEV1 non-structural proteins were studied through the expression of fusion proteins. None of the proteins expressed were able to induce membrane changes similar to those seen during HPEV1 infection. However, the 2C protein, which could be found on the surface of lipid droplets but also on diverse intracellular membranes, was partly relocated to viral replication complexes in transfected, superinfected cells. Although Golgi to ER traffic was arrested in HPEV1-infected cells, none of the individually expressed non-structural proteins had any visible effect on the anterograde membrane traffic. Our results suggest that the HPEV1 replication strategy is different from that of many other picornaviruses. Furthermore, this study shows how relatively small differences in genome sequence result in very different intracellular pathology.

Elimination of axial venous reflux

Chronic venous disease (CVD), including uncomplicated varicose veins and chronic venous insufficiency, is one of the most common medical conditions in the Western world. The central feature of CVD is venous reflux, which may be primary, congenital, or result from an antecedent event, usually an acute deep venous thrombosis (DVT). When the history of DVT is clear, the clinical manifestations of secondary CVD are commonly referred to as the post-thrombotic syndrome. Regardless of the underlying etiology, the final pathway leading to symptoms is ambulatory venous hypertension. The spectrum of symptoms and signs of CVD ranges from minor cosmetic problems to venous ulceration, which results in considerable morbidity and increased medical costs. Aims of this study were to evaluate the outcome of superficial venous surgery performed with or without preoperative duplex evaluation and venous marking with hand-held doppler, to assess short-term outcome of ultrasound-guided foam sclerotherapy in patients with axial superficial venous incompetence, as well as to compare reflux patterns after catheter-directed and systemic thrombolysis of deep ileofemoral venous thrombosis, and to evaluate the long-term outcome of deep venous reconstructions for severe chronic venous insufficiency. The study consists of five separate retrospective projects and includes 315 patients. Of this, 133 patients had undergone superficial venous surgery 2 to 5 years earlier according to preoperative duplex examination and venous marking, or according to clinical evaluation alone, or to a written plan without venous marking. A total of 112 patients had undergone ultrasound-guided foam sclerotherapy 5.5 to 16.5 months before. In addition, 32 patients had received either catheter-directed or systemic thrombolysis for DVT 2 to 3 years earlier, and 38 patients had undergone deep venous reconstructions 2 to 7 years earlier. In the present studies, some venous reflux was present postoperatively irrespective of the method of evaluation or ablation of the reflux. It seemed, however, that preoperative examination with duplex ultrasound and marking of reflux sites before the operation by the operating surgeon improves the outcome of superficial venous surgery. Ultrasound-guided foam sclerotherapy is effective in elimination of venous reflux in selected cases in short-term follow-up. Catheter-directed thrombolysis for deep iliofemoral venous thrombosis reduces later reflux and most probably the development of post-thrombotic syndrome as well. The outcome of deep venous reconstructions, especially for post-thrombotic deep venous incompetence, is poor. Thus, prevention of valvular damage by active treatment of deep venous thrombosis is important.