11β-hydroxysteroid dehydrogenase type 1 has no effect on survival during experimental malaria but affects parasitemia in a parasite strain-specific manner

status: publishe

NMR Studies on Structure and Dynamics of the Monomeric Derivative of BS-RNase: New Insights for 3D Domain Swapping

Three-dimensional domain swapping is a common phenomenon in pancreatic-like ribonucleases. In the aggregated state, these proteins acquire new biological functions, including selective cytotoxicity against tumour cells. RNase A is able to dislocate both N- and C-termini, but usually this process requires denaturing conditions. In contrast, bovine seminal ribonuclease (BS-RNase), which is a homo-dimeric protein sharing 80% of sequence identity with RNase A, occurs natively as a mixture of swapped and unswapped isoforms. The presence of two disulfides bridging the subunits, indeed, ensures a dimeric structure also to the unswapped molecule. In vitro, the two BS-RNase isoforms interconvert under physiological conditions. Since the tendency to swap is often related to the instability of the monomeric proteins, in these paper we have analysed in detail the stability in solution of the monomeric derivative of BS-RNase (mBS) by a combination of NMR studies and Molecular Dynamics Simulations. The refinement of NMR structure and relaxation data indicate a close similarity with RNase A, without any evidence of aggregation or partial opening. The high compactness of mBS structure is confirmed also by H/D exchange, urea denaturation, and TEMPOL mapping of the protein surface. The present extensive structural and dynamic investigation of (monomeric) mBS did not show any experimental evidence that could explain the known differences in swapping between BS-RNase and RNase A. Hence, we conclude that the swapping in BS-RNase must be influenced by the distinct features of the dimers, suggesting a prominent role for the interchain disulfide bridges

Comparison of coronal leakage of different root canal filling techniques: an ex vivo study

The aim of this study was to compare the quality of the coronal seal, using an in vitro bacterial invasion test, of three different root canal filling systems. Twenty-seven freshly extracted mandibular premolars were selected and divided into three experimental groups (G1, G2 and G3 n=7) and two control groups (Ct+ and Ct- n=3). All teeth in the experimental groups were prepared using NiTi Mtwo rotating instruments and then the endodontic treatments were completed using the three-tested warm guttapercha root filling techniques: Microseal (G1), Thermafil (G2) and System B (G3). All root filling techniques were performed using the same endodontic sealer (Pulp Canal Sealer). Three teeth were instrumented and not filled, serving as positive controls (Ct+) and the last three teeth, with intact crowns and no endodontic treatment, served as negative controls (Ct-). All samples were mounted in a two-chamber apparatus and exposed to Enterococcus faecalis performing a bacterial infiltration test. All samples were observed for a maximum period of 60 days checking for turbidity of the BHI broth on a daily basis recording when contamination occurred. A quantitative evaluation of the bacterial CFU/ml was performed using the URO-QUICK\u99 system. On day 32 an overall value was recorded of contamination of 42.85% for group G1, 71.42% for G2 and 42.85% for G3; after 60 days, the final contamination result was 85.71% for group G1, and 100% for both G2 and G3 groups. Considering the number of contaminated samples at the end of the observation period, the three techniques showed no statistically significant differences. The study highlighted the bacterial permeability of gutta-percha/seal barrier, underlining the importance of an effective coronal restoration to ensure a durable seal after root canal treatment

Comparison of coronal leakage of different root canal filling techniques: an ex vivo study

The aim of this study was to compare the quality of the coronal seal, using an in vitro bacterial invasion test, of three different root canal filling systems. Twenty-seven freshly extracted mandibular premolars were selected and divided into three experimental groups (G1, G2 and G3 n=7) and two control groups (Ct+ and Ct- n=3). All teeth in the experimental groups were prepared using NiTi Mtwo rotating instruments and then the endodontic treatments were completed using the three-tested warm guttapercha root filling techniques: Microseal (G1), Thermafil (G2) and System B (G3). All root filling techniques were performed using the same endodontic sealer (Pulp Canal Sealer). Three teeth were instrumented and not filled, serving as positive controls (Ct+) and the last three teeth, with intact crowns and no endodontic treatment, served as negative controls (Ct-). All samples were mounted in a two-chamber apparatus and exposed to Enterococcus faecalis performing a bacterial infiltration test. All samples were observed for a maximum period of 60 days checking for turbidity of the BHI broth on a daily basis recording when contamination occurred. A quantitative evaluation of the bacterial CFU/ml was performed using the URO-QUICK\u99 system. On day 32 an overall value was recorded of contamination of 42.85% for group G1, 71.42% for G2 and 42.85% for G3; after 60 days, the final contamination result was 85.71% for group G1, and 100% for both G2 and G3 groups. Considering the number of contaminated samples at the end of the observation period, the three techniques showed no statistically significant differences. The study highlighted the bacterial permeability of gutta-percha/seal barrier, underlining the importance of an effective coronal restoration to ensure a durable seal after root canal treatment