Jožef Stefan Institute

About: Jožef Stefan Institute is a facility organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Liquid crystal & Dielectric. The organization has 3828 authors who have published 12614 publications receiving 291025 citations.

Nonspecific interactions in spontaneous assembly of empty versus functional single-stranded RNA viruses.

Abstract: We investigate the influence of salt concentration, charge on viral proteins and the length of single-stranded RNA (ssRNA) molecule on the spontaneous assembly of viruses. Only the nonspecific interactions are assumed to guide the assembly, i.e., we exclude any chemical specificity that may lock the viral proteins and ssRNA in preferred configurations. We demonstrate that the electrostatic interactions screened by the salt in the solution impose strong limits on viral composition that can be achieved by spontaneous assembly. In particular, we show that viruses whose ssRNA carries more than twice the amount of charge that is located on the viral proteins, cannot be assembled spontaneously. We find that the spatial distribution of protein charge is important for the energetics of the assembly. We also show that the pressures that act on the viruses as a result of attractive protein-ssRNA electrostatic interactions are at least an order of magnitude smaller than is the case with bacteriophage viruses that contain double-stranded DNA molecule.

Human cathepsin B is a metastable enzyme stabilized by specific ionic interactions associated with the active site.

Abstract: The effect of neutral or alkaline pH on cathepsin B activity and structure was investigated. An irreversible loss of activity, accompanied by large structural changes, was observed at pH > or = 7.0. The high activation energy of 183.5 kJ mol-1, calculated for the inactivation process, is in good agreement with structural changes observed by circular dichroism. Both the pH-induced inactivation and the pH-induced unfolding of cathepsin B were found to be first-order processes, exponentially increasing with increasing pH of the solution. The good agreement of the rate constants of inactivation and unfolding of the enzyme indicates an important structure-function relationship. Cathepsin B was also found to be destabilized both by increasing ionic strength and organic solvent content.

Restoration of Gait During Two to Three Weeks of Therapy with Multichannel Electrical Stimulation

Abstract: Multichannel electrical stimulation was applied in 20 patients with hemiplegia secondary to stroke or head injury using a six-channel microprocessor stimulator-stride analyzer to restore independent gait and to reestablish a normal gait pattern in a two- to three-week therapy period. The therapy was followed up at every session by a stride analyzer incorporated into the stimulator. At the beginning and at the end of the therapy period, each subject's gait was measured with a ground reaction measuring system. Statistical results and observations are presented for the group of 20 subjects, and a detailed description of the results is given for one subject who is representative of the whole group. According to the measured gait characteristics, gait improved significantly in all subjects during the therapy period, resulting in a partly or completely independent gait. The subjects' posture and endurance also improved, and they spontaneously learned how to use a crutch. The measurements and visual assessment of the subjects' progress indicate that the described treatment protocol offers good prospects for faster and more efficient gait rehabilitation in severely impaired patients. To determine the efficacy of gait therapy with multichannel electrical stimulation, a comparative study of conventional therapeutic methods and the method described in this article should be conducted.