Yip, W. S. Vincent
Taylor, David W.
Ribosomal RNA (rRNA) modifications are essential for ribosome function in all cellular organisms. Box C/D small (nucleolar) ribonucleoproteins [s(no)RNPs] catalyze 2'-O-methylation, one rRNA modification type in Eukarya and Archaea. Negatively stained electron microscopy (EM) models of archaeal box C/D sRNPs have demonstrated the dimeric sRNP (di-sRNP) architecture, which has been corroborated by nuclear magnetic resonance (NMR) studies. Due to limitations of the structural techniques, the orientation of the box C/D sRNAs has remained unclear. Here, we have used cryo-EM to elucidate the sRNA orientation in a M. jannaschii box C/D di-sRNP. The cryo-EM reconstruction suggests a parallel orientation of the two sRNAs. Biochemical and structural analyses of sRNPs assembled with mutant sRNAs indicate a potential interaction between the sRNA stem ends. Our results suggest that the parallel arrangement of the sRNAs juxtaposes their stem ends into close proximity to allow for a stabilizing interaction that helps maintain the di-sRNP architecture.
The first total syntheses of chaetoglines C-F via a bioinspired and divergent synthetic strategy are reported. Chaetolines C and D were obtained from the condensation of hemiacetal and tryptophan methyl ester building blocks followed by functional group transformations. The synthesis of chaetogline E employed the diastereoselective Pictet-Spengler reaction, and the tetrahydro-carboline skeleton was further utilized as a precursor for an oxidative aromatization reaction to introduce the beta-carboline moiety of chaetogline F.
Capuzzo Dolcetta, Italo; Leoni, Fabiana; Vitolo, Antonio
We consider fully nonlinear degenerate elliptic equations with zero and first order terms. We provide a priori upper bounds and characterize the existence of entire subsolutions under growth conditions on the lower order coefficients which extend the classical Keller-Osserman condition for semilinear equations.
Giuseppe Andrea Ferro
Abstract Nowadays an environmental problem that cannot be underestimated is the increasing amount of waste of different nature. Certainly, an environmental friendly solution is to use waste directly or indirectly in the production of concrete or mortar, which are the most used building materials in the world. In the production of coarse recycled aggregates (RA), the fine fraction, also called recycled sand (RS), is involuntarily produced and it represents a large amount of the weight of the crushed C&D waste. Generally, the problem of fine fraction has not been much analysed until now. For this reason, in this work, an innovative mortar mix design for using recycled sand from C&D has been analysed, by partial replacement of standardized sand (SS) with recycled sand (RS) or washed recycled sand (RSW) and by using a fixed w/c ratio equal to 0,5. The main aim of this research has been to investigate if washing and sieving of recycled aggregates can improve the quality of the recycled aggregate. Analyses allowed concluding that the quality of the recycled aggregate could be improved by washing and sieving of recycled aggregates and that in any case the bending strength and the fracture energy increase or decrease simultaneously.
Background/Aims. Tacrolimus is an immunosuppressive drug. Its CO concentration, commonly used for monitoring, does not always correspond to its pharmacologic effect. Tholking et al developed an indicator, the C/D ratio, that describes the drug's metabolism rate. Our purpose was to determine whether the points dividing the patients into fast, intermediate, and slow metabolizers that were assumed by those authors would be similar for long-term follow-up after renal transplantation (RTx).Methods. We examined the C/D ratio in 571 patients at their most recent appointments-1 year and more after renal transplantation. The mean time after RTx was 84 months. We studied kidney function both at the most recent appointment and early after RTx.Results. The median C/D ratio for our group was 1.68. Our observations revealed a negative correlation between the C/D ratio and creatinine concentration and a positive correlation between the C/D ratio and eGFR concentration long term after RTx. We formulated a C/D ratio cutoff point between an eGFR < and > 60 mL/min/1.73 m(2) and came up with the value of 1.53. It was found that between the < 1.53 and > 1.53 groups, there were significant differences in creatinine and eGFR concentrations at the most recent appointment, as well as differences in how creatinine and eGFR levels varied over time between RTx and the most recent observation.Conclusions. The C/D ratio is useful for assessing the effect of the tacrolimus metabolism rate on long-term renal function. We propose the C/D ratio value of 1.53 as the cutoff point below which the ratio provides a negative prognosis for long-term renal function.