Single pulse modeling and the bi-drifting subpulses of radio pulsar B1839-04

We study the bi-drifting pulsar B1839-04, where the observed subpulse drift direction in the two leading pulse components is opposite from that in the two trailing components. Such diametrically opposed apparent motions challenge our understanding of an underlying structure. We find that for the geometry spanned by the observer and the pulsar magnetic and rotation axes, the observed bi-drifting in B1839-04 can be reproduced assuming a non-dipolar configuration of the surface magnetic field. Acceptable solutions are found to either have relatively weak $(\sim 10^{12} \,{\rm G})$ or strong $(\sim 10^{14} \,{\rm G})$ surface magnetic fields. Our single pulse modeling shows that a global electric potential variation at the polar cap that leads to a solid-body-like rotation of spark forming regions is favorable in reproducing the observed drift characteristics. This variation of the potential additionally ensures that the variability is identical in all pulse components resulting in the observed phase locking of subpulses. Thorough and more general studies of pulsar geometry show that a low ratio of impact factor to opening angle $(\beta / \rho)$ increases the likelihood of bi-drifting to be observed. We thus conclude that bi-drifting is visible when our line of sight crosses close to the magnetic pole.Comment: 15 pages, 14 figures, accepted for publication in Ap

Recombinant angioarrestin secreted from mouse melanoma cells inhibits growth of primary tumours

Angioarrestin is a recently described anti-angiogenic protein whose expression is down-regulated in solid tumours of various origins. It has a sequence identical to angiopoietin related protein-1. In this study we investigated anti-tumour properties of angioarrestin in B16 (F10) melanoma tumour model. We constructed an expression vector encoding human angioarrestin under the control of EF-1α promoter. This vector was transferred to B16 (F10) cells and recombinant angioarrestin secreted from the transfected cells was tested for anti-angiogenic activity using endothelial cell proliferation assay. Finally, mice were injected subcutaneously with cells that had been transfected with either angioarrestin-encoding vector or empty vector and tumor growth was compared. The obtained recombinant angioarrestin inhibited proliferation of bovine aortic endothelial cells. Tumours derived from an angioarrestin-secreting B16 (F10) cell clone grew in vivo more slowly than tumours derived from a cell clone transfected with empty vector. These data show, to our knowledge for the first time, that angioarrestin can inhibit primary melanoma tumour growth

Innovative biodegradable dibutyrylchitin dressing for the treatment of ulcers occurring during chronic venous insufficiency in patients with type 2 diabetes

The aim of this study was to assess the course of the healing process following the use of dibutyrylchitin (DBC) dressing, a fully degradable material used in the treatment of ulcers which occur during chronic venous insufficiency common in patients suffering from type 2 diabetes. These diseases have a significant impact on the patients’ standard of living, including the potential employment, and on the declining attendance at the current workplace. The implementation of this innovative therapeutic solution may positively affect the above-mentioned difficulties. An analysis of the healing process, following the application of the DBC dressing, was performed. Once the dressing was positioned on the wound, the analysis indicated that it underwent a process of degradation facilitated by the enzymes occurring naturally in the wound. When fully degraded, a further layer was applied. This process was repeated until the wound was fully healed. The study group consisted of 4 patients previously diagnosed with type 2 diabetes. During the observation period, the ulcers in all 4 cases had healed. The examined wound dressings adhered well to the wound surface and degraded within it. No side effects or adverse effects of the applied innovative therapy were observed. An addition of the biodegradable DBC dressing to the standard therapy procedure of ulcers occurring during chronic venous insufficiency among patients with type 2 diabetes indicate safe and effective treatment, which may have a direct reflection in the patient’s professional capacity enhancement. It resulted in the complete healing of all ulcers in each of the observed cases