Solution-state structure of a fully alternately 2′-F/2′-OMe modified 42-nt dimeric siRNA construct

A high-resolution solution structure of a stable 42-nt RNA dimeric construct has been derived based on a high number of NMR observables including nuclear overhauser effects (NOEs), J-coupling constants and residual dipolar couplings (RDCs), which were all obtained with isotopically unlabeled molecules. Two 21-nt siRNA that efficiently hybridize consist of ribose units that were alternately substituted by 2′-fluoro or 2′-methoxy groups. Structure calculations utilized a set of H-F RDC values for all 21 2′-fluoro modified nucleotides under conditions of weak alignment achieved by Pf1 phages. A completely 2′-F/2′-OMe modified dimeric RNA construct adopts an antiparallel double-helical structure consisting of 19 Watson–Crick base pairs with additional 3′ UU overhangs and a 5′ phosphate group on the antisense strand. NMR data suggest that the stability of individual base pairs is not uniform throughout the construct. While most of the double helical segment exhibits well dispersed imino resonances, the last three base pairs either display uncharacteristic chemical shifts of imino protons or absence of imino resonances even at lower temperatures. Accessibility of imino protons to solvent exchange suggests a difference in stability of duplex ends, which might be of importance for incorporation of the guide siRNA strand into a RISC

Foreign objects in teeth: Retrieval and management

The discovery of foreign bodies in the teeth is a special situation, which is often diagnosed accidentally. Detailed case history, clinical and radiographic examinations are necessary to come to a conclusion about the nature, size, location of the foreign body and the difficulty involved in its retrieval. It is more common to find this situation in children as it is a well-known fact that children often tend to have the habit of placing foreign objects in the mouth. Sometimes the foreign objects get stuck in the root canals of the teeth, which the children do not reveal to their parents due to fear. These foreign objects may act as a potential source of infection and may later lead to a painful condition. This paper discusses the types of foreign objects found in and around the teeth and reports two cases along with their retrieval and associated management of the involved teeth

Studies to optimize the process of biofuel production from castor stalk

Lignocellulosic biomass is a rich source of cellulose and one of the most promising raw materials for the production of biofuels and other value added chemicals. However, its high lignin content and complex cellular structure represent a significant processing challenge. In this work, the effect of pretreatment using [EMIM][Ac] was studied at various process parameters in order to develop a cost-effective process. In order to minimize the loss of sugars in this process bulk of the solids, comprising both regenerated cellulose and undissolved particles were subjected to the enzymatic hydrolysis. Up to 96 % enzymatic digestibility was achieved, even with relatively coarse particle sizes (0.6-1.0 mm range), at 10 % biomass loading. The enhanced digestibility of CS is attributed to reduction in lignin content, crystallinity of the cellulose coupled with an increase in surface area