Riboswitches harness the structural and dynamic sophistication of RNA to coordinate specific ligand recognition with changes in gene expression. Design of molecules to manipulate riboswitch responses relies on our understanding of their RNA−ligand interactions. Here we demonstrate that for the adenine (A) riboswitch (ARNA) these interactions are highly dynamic. Given that 2-aminopurine (Ap) mimics A in its interactions with ARNA, we use the fluorescence lifetime of Ap to interrogate individual Ap-ARNA conformers (dynamic exchange times > ∼10 ns). Counter to predictions of two state and induced fit models, the ligand-bound A riboswitch is not a single, highly ordered structure:  We detect at least three distinct Ap-ARNA conformers in ensemble solution. Their distribution indicates that they are not high-energy RNA folding intermediates but are instead energetically similar (ΔG < 1 kcal mol-1) conformers whose thermal stability, ligand, and Mg2+ binding affinity differ substantially. Our experimental charac...

In our investigation,we used short-time model of myocardial infarction of rats induced by high dose of isoproterenol (ISP). We investigated cardiac troponin T blood level (cTnT) and histological characteristics of rat myocardium. ISP, single, intraperitoneal dose 250 mg/kg was given to male, adult, Wistar rats (n=12). Rats were distributed depending on their body weight in subgroups: ISP I (BW 260-280g) and ISP II (BW 250-400g).Control group (n=9) was treated with intraperitoneal dose of 0,95% NaCl. Cardiac TnT was measured by electrochemiluminiscence (ECLA) sandwich immunoassay in rat serum 4 hours after ISP application. Rats' hearts were dissected and examined by qualitative histological method (HE). Statistical significance was set at 0,05. There was significant difference in cTnT of ISP II (p=0,0001) vs. control and ISP I (p<0,05) vs. control. Significant difference was between ISP I and ISP II subgroups (p<0.001). The accent of histological changes of myocardium was on nuclei of cell. Cells showed acidophilic changes and nuclei disappearance as signs of coagulative necrosis development. Extensivity of histological changes were different between ISP I and ISP II subgroup. Used dose of ISP induced development of myocardial necrosis in rats. Subendocardial portion of myocardium was more vulnerability than subepicardial portion. Rats of ISP II had more extensive histological changes than these in ISP I. Administered doses of ISP enabled cTnT utilization as a marker of myocardial necrosis.

Hexagon TB is intended for the rapid diagnostics of tuberculosis. Tuberculosis is a contagious and epidemic disease. According to the data published by WHO, 3-4 millions of patients are diagnosed with this disease annually. In 2004, 107 new cases were discovered in the area of Tuzla Municipality. Annual incidence of this disease is 62,9 per 100 000 inhabitants in Bosnia and Herzegovina; 28,9 in Slovenia; 33,2 in FYRM; 48,5 in Croatia; 41,8 in Serbia and Montenegro. Western European countries have a rather low rate of the disease--5-10 cases per 100 000 inhabitants. Efficiency of Hexagon TB examination method was tested on 100 patients. The subjects were patients with clinical symptoms of active TBC infection, persons who were in contact with TBC patients and persons earlier cured of TBC. All the subjects were tested with Hexagon TB, and the results were compared against lungs X-rays and sputum test for BK and LOW. Hexagon TB is intended for rapid, qualitative detection of IgG, IgA, IgM antibodies against M. tuberculosis and mycobacterium in human serum, plasma or whole blood as an aid in the early diagnostics of tuberculosis infections for professional use. Hexagon TB was positive in 11 of the examined patients. 10 patients had changes suggesting TBC. 1 patient was directly positive for BK and 3 patients were positive for LOW. Of all the examined patients, 3 were positive for all tests positive. According to our results, Hexagon TB has significant importance in practice of rapid TBC diagnostics compared to lungs X-ray and examination of sputum for BK and LOW.