Weak Intra-Ring Allosteric Communications of the Archaeal Chaperonin Thermosome Revealed by Normal Mode Analysis

AbstractChaperonins are molecular machines that use ATP-driven cycles to assist misfolded substrate proteins to reach the native state. During the functional cycle, these machines adopt distinct nucleotide-dependent conformational states, which reflect large-scale allosteric changes in individual subunits. Distinct allosteric kinetics has been described for the two chaperonin classes. Bacterial (group I) chaperonins, such as GroEL, undergo concerted subunit motions within each ring, whereas archaeal and eukaryotic chaperonins (group II) undergo sequential subunit motions. We study these distinct mechanisms through a comparative normal mode analysis of monomer and double-ring structures of the archaeal chaperonin thermosome and GroEL. We find that thermosome monomers of each type exhibit common low-frequency behavior of normal modes. The observed distinct higher-frequency modes are attributed to functional specialization of these subunit types. The thermosome double-ring structure has larger contribution from higher-frequency modes, as it is found in the GroEL case. We find that long-range intersubunit correlation of amino-acid pairs is weaker in the thermosome ring than in GroEL. Overall, our results indicate that distinct allosteric behavior of the two chaperonin classes originates from different wiring of individual subunits as well as of the intersubunit communications

Effect of addition of titanium dioxide nanoparticles on the antimicrobial properties, surface roughness and surface hardness of polymethyl methacrylate: A Systematic Review

Supplementary Material for the systematic review on effect of addition of TiO2NP in PMMA denture base resi

Awareness, attitudes, need and demand on replacement of missing teeth among a group of partially dentate patients attending a University Dental Hospital

Abstract Objective Our objective was to assess awareness, attitudes, need and demand on replacement of missing teeth according to edentulous space, age, gender, ethnicity, educational level and socio-economical status of the patient. Results 76.2% of the study group was opined that the missing teeth should be replaced by prosthetic means. Majority were keen in getting them replaced mainly for the comfort in mastication. Although 77.9 and 32.9% were aware of the removable prostheses and implants respectively, only 25.2% knew about tooth supported bridges as an option of replacement of missing teeth. Participants’ awareness on tooth and implant supported prostheses is at a higher level. Participants’ opinion on need of regular dental visit was statistically significant when gender, ethnicity and education level were considered. The highest demand for replacement of missing teeth was observed in Kennedy class I and II situations in both upper and lower arches. Demand for fixed prostheses was significantly highest in Kennedy class II in upper and lower arches. In conclusion, although removable prosthodontic options are known to most of the patients, their awareness on tooth and implant supported prostheses is also at a higher level. The highest demand for replacement of missing teeth is by patients with Kennedy class I and II situations whereas Kennedy class II being the category with highest demand for fixed prostheses. We recommend that the location of missing teeth to be considered as a priority when educating patients on the most appropriate prosthetic treatment options. Dentists’ involvement in educating patients on prosthetic options needs to be improved

Linear and Volumetric Analysis of Maxillary Sinus Pneumatization in a Sri Lankan Population Using Cone Beam Computer Tomography

Objective. The objectives of this study were to evaluate the linear and volumetric measurements of the maxillary sinus in relation to sex and side on cone beam computer tomographic (CBCT) images in a Sri Lankan population. Methods. A total of 20 sets of CBCT images selected from the database at the Division of Oral Medicine and Radiology, Faculty of Dental Sciences, University of Peradeniya, Sri Lanka, were evaluated. Linear measurements were obtained in a craniocaudal (height), anteroposterior (length), and mediolateral (width) dimensions. Volume was computed by using the same data using a computerized 3D modeling software developed for 3D measurements and calculations. Results. The maximum mean craniocaudal dimension was at the level of the 1st and the 2nd molar tooth bilaterally. The largest average craniocaudal, mediolateral, and anteroposterior extensions of the maxillary sinus using CBCT were 31.71±5.44 mm, 21.28±5.09 mm, and 32.92±4.31 mm, respectively. The differences between the sides and sex showed no statistical significance (P>0.05), except for the maximum average value in craniocaudal dimension which showed a statistically significant difference in relation to gender (P=0.02). Conclusion. There is no significant difference in the largest average craniocaudal, mediolateral, and anteroposterior extensions of the maxillary sinus when gender and side were compared. However, the maximum average value in craniocaudal dimension had a statistically significant difference in relation to gender. This study provides valuable knowledge of the anatomical dimensions of the maxillary sinus which may help clinicians in treatment planning

Perceptions of Dental Undergraduates Towards Online Education During COVID-19: Assessment From India, Nepal and Sri Lanka

Purpose: The social distancing mandates instituted during COVID-19 pandemic mark the sudden transition in the mode of dental education’s delivery to the virtual instruction. It is vital to assess students’ perceptions towards virtual learning environments, particularly among those gaining education in resource-strained countries. This cross-sectional study aims to assess the perceptions of dental undergraduates towards online education, environment and transferable skills and patient care during COVID-19 in India, Nepal, and Sri Lanka. Materials and Methods: Dental preclinical and clinical undergraduate students from India, Nepal and Sri Lanka were recruited from November 2020 to March 2021 through a 47-item web-based survey consisting of psychometrically valid subscales of Dundee Ready Educational Environment Measure (DREEM) and Transferable Skills Questionnaire. The mean scores of students’ perceptions of learning, environment, and patient care skills were compared among preclinical and clinical students of the participating countries. Results: Of total 930 participants, 44.4% were from India, 26.1% from Sri Lanka and 29.5% responses from Nepal. Sri Lanka reported the highest mean scores across all domains of perception indicative of positive attitude. Clinical students from all participating countries had statistically significantly higher positive perception of transferable skills in patient care as opposed to their preclinical counterparts. On the contrary, perception towards learning was higher among preclinical students as opposed to clinical students. These differences were statistically significant for Nepal and Sri Lanka. Conclusion: The findings of this study underscore the need to develop and implement effective online dental educational interventions to foster academic growth and essential practical skills without compromising academic rigor and continuity in the dental education curriculum