Comparative Evaluation of Antimicrobial Efficacy of Diode Laser (Continuous Mode), Diode Laser (Pulse Mode), and 5.25% of Sodium Hypochlorite in Disinfection of Root Canal: A Short Study.

Introduction: The success of endodontic treatment is achieved by the complete elimination of pulpal infection and protection from future invasion of microorganisms. Due to the complex structure of the root canal, complete eradication of microorganisms is not possible and is a major challenge for successful endodontic treatment. Therefore, microbiological studies are needed to explore the effect of various disinfection methods. Aim and objective: The aim of this study is to compare the effectiveness of root canal disinfection by using a diode laser (in pulse and continuous modes) and sodium hypochlorite by microbiological assessment. Materials and methods: Forty-five patients were selected and randomly divided into three groups. After gaining patency to the root canal the first sample from the root canal was taken using a sterile absorbent paper point and transferred to a sterile tube containing a normal saline medium. Biomechanical preparation was performed with Dentsply Protaper hand files of each corresponding group and was disinfected with group I (diode light amplification by stimulated emission of radiation (LASER) 980 nm with 3 W in continuous mode for 20 seconds), group II (diode LASER 980 nm with 3 W in pulse mode for 20 seconds), group III (irrigated with 5.25% of sodium hypochlorite for 5 minutes). Pre- and post-samples of each group were inoculated on sheep blood agar and examined for any bacterial growth. After the microbial evaluation of the total microbial count of pre- and post-samples, the data obtained were tabulated and statistically analyzed. Results: The data were evaluated and analyzed using analysis of variance (ANOVA) on Statistical Package for the Social Sciences (SPSS) software. Groups I, II, and III all three groups showed significant differences (p < 0.01) and an overall reduction in the microbial count at postbiomechanical preparation (BMP) as compared to pre-BMP with the highest being in laser in continuous mode (group I) (91.9%), followed by 5.25% sodium hypochlorite (group III) (86.5%) and LASER in pulse mode (group II) (72.0%) the least. Conclusion: The study concluded that the diode laser in continuous mode is more efficacious than the diode laser in pulse mode and 5.2% sodium hypochlorite, respectively. How to cite this article: Mishra A, Koul M, Abdullah A, et al. Comparative Evaluation of Antimicrobial Efficacy of Diode Laser (Continuous Mode), Diode Laser (Pulse Mode), and 5.25% of Sodium Hypochlorite in Disinfection of Root Canal: A Short Study. Int J Clin Pediatr Dent 2022;15(5):579-583.

A Comparative Evaluation of Shear Bond Strength of Seventh- and Eighth-Generation Self-etch Dentin Bonding Agents in Primary Teeth: An In Vitro Study.

AIM: To compare the shear bond strength of seventh- and eight-generation self-etch dentin bonding agents in primary teeth using universal testing machine. MATERIALS AND METHODS: Forty extracted sound human primary molars were collected and randomly divided into two groups of 20 sample each. Shear bond strength of seventh-generation bonding agent [ADPER Single Bond Universal, (group II)] and eighth-generation bonding agent [Futurabond DC, VOCO Germany, (group I)] were calculated by using Universal Testing Machine (PTC/O83/ME, INSTRON, USA) and expressed in megapascals (MPa). Recorded data were compiled and subjected to statistical analysis using Student's t test. RESULTS: The mean shear bond strength of group I (eighth-generation dentin bonding agent) and group II (seventh-generation dentin bonding agent) ranged from 22.10 to 37.10 MPa and 19.80 to 30.30 MPa, respectively Student's t test showed significantly different and higher (8.7%) shear bond strength in group I when compared to group II (p value = 0.017). CONCLUSION: Shear bond strength of eighth-generation dentin bonding agent (Futurabond DC) was better than seventh-generation dentin bonding agent (Adper Single Bond Universal). CLINICAL SIGNIFICANCE: An effective bond to tooth would reduce marginal microleakage, bacterial penetration, postoperative sensitivity, possibility of pulpal inflammation, and preserve tooth structure by allowing minimal cavity preparation. HOW TO CITE THIS ARTICLE: Mishra A, Koul M, Upadhyay VK, et al. A Comparative Evaluation of Shear Bond Strength of Seventh- and Eighth-generation Self-etch Dentin Bonding Agents in Primary Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(3):225-229.

Flexible and Extended Linker Domains Support Efficient Targeting of Heh2 to the Inner Nuclear Membrane.

The nuclear pore complex (NPC) is embedded in the nuclear envelope and forms the main gateway to the nuclear interior including the inner nuclear membrane (INM). Two INM proteins in yeast are selectively imported. Their sorting signals consist of a nuclear localization signal, separated from the transmembrane domain by a long intrinsically disordered (ID) linker. We used computational models to predict the dynamic conformations of ID linkers and analyzed the INM targeting efficiency of proteins with linker regions with altered Stokes radii and decreased flexibilities. We find that flexibility, Stokes radius, and the frequency at which the linkers are at an extended end-to-end distance larger than 25 nm are good predictors for the targeting of the proteins. The data are consistent with a transport mechanism in which INM targeting of Heh2 is dependent on an ID linker that facilitates the crossing of the approximately 25-nm thick NPC scaffold.

Age-dependent deterioration of nuclear pore assembly in mitotic cells decreases transport dynamics.

Nuclear transport is facilitated by the Nuclear Pore Complex (NPC) and is essential for life in eukaryotes. The NPC is a long-lived and exceptionally large structure. We asked whether NPC quality control is compromised in aging mitotic cells. Our images of single yeast cells during aging, show that the abundance of several NPC components and NPC assembly factors decreases. Additionally, the single-cell life histories reveal that cells that better maintain those components are longer lived. The presence of herniations at the nuclear envelope of aged cells suggests that misassembled NPCs are accumulated in aged cells. Aged cells show decreased dynamics of transcription factor shuttling and increased nuclear compartmentalization. These functional changes are likely caused by the presence of misassembled NPCs, as we find that two NPC assembly mutants show similar transport phenotypes as aged cells. We conclude that NPC interphase assembly is a major challenge for aging mitotic cells.

The Effect of FG-Nup Phosphorylation on NPC Selectivity: A One-Bead-Per-Amino-Acid Molecular Dynamics Study.

Nuclear pore complexes (NPCs) are large protein complexes embedded in the nuclear envelope separating the cytoplasm from the nucleoplasm in eukaryotic cells. They function as selective gates for the transport of molecules in and out of the nucleus. The inner wall of the NPC is coated with intrinsically disordered proteins rich in phenylalanine-glycine repeats (FG-repeats), which are responsible for the intriguing selectivity of NPCs. The phosphorylation state of the FG-Nups is controlled by kinases and phosphatases. In the current study, we extended our one-bead-per-amino-acid (1BPA) model for intrinsically disordered proteins to account for phosphorylation. With this, we performed molecular dynamics simulations to probe the effect of phosphorylation on the Stokes radius of isolated FG-Nups, and on the structure and transport properties of the NPC. Our results indicate that phosphorylation causes a reduced attraction between the residues, leading to an extension of the FG-Nups and the formation of a significantly less dense FG-network inside the NPC. Furthermore, our simulations show that upon phosphorylation, the transport rate of inert molecules increases, while that of nuclear transport receptors decreases, which can be rationalized in terms of modified hydrophobic, electrostatic, and steric interactions. Altogether, our models provide a molecular framework to explain how extensive phosphorylation of FG-Nups decreases the selectivity of the NPC.

DNA origami scaffold for studying intrinsically disordered proteins of the nuclear pore complex.

The nuclear pore complex (NPC) is the gatekeeper for nuclear transport in eukaryotic cells. A key component of the NPC is the central shaft lined with intrinsically disordered proteins (IDPs) known as FG-Nups, which control the selective molecular traffic. Here, we present an approach to realize artificial NPC mimics that allows controlling the type and copy number of FG-Nups. We constructed 34 nm-wide 3D DNA origami rings and attached different numbers of NSP1, a model yeast FG-Nup, or NSP1-S, a hydrophilic mutant. Using (cryo) electron microscopy, we find that NSP1 forms denser cohesive networks inside the ring compared to NSP1-S. Consistent with this, the measured ionic conductance is lower for NSP1 than for NSP1-S. Molecular dynamics simulations reveal spatially varying protein densities and conductances in good agreement with the experiments. Our technique provides an experimental platform for deciphering the collective behavior of IDPs with full control of their type and position.

Spatial structure of disordered proteins dictates conductance and selectivity in nuclear pore complex mimics.

Nuclear pore complexes (NPCs) lined with intrinsically disordered FG-domains act as selective gatekeepers for molecular transport between the nucleus and the cytoplasm in eukaryotic cells. The underlying physical mechanism of the intriguing selectivity is still under debate. Here, we probe the transport of ions and transport receptors through biomimetic NPCs consisting of Nsp1 domains attached to the inner surface of solid-state nanopores. We examine both wildtype FG-domains and hydrophilic SG-mutants. FG-nanopores showed a clear selectivity as transport receptors can translocate across the pore whereas other proteins cannot. SG mutant pores lack such selectivity. To unravel this striking difference, we present coarse-grained molecular dynamics simulations that reveal that FG-pores exhibit a high-density, nonuniform protein distribution, in contrast to a uniform and significantly less-dense protein distribution in the SG-mutant. We conclude that the sequence-dependent density distribution of disordered proteins inside the NPC plays a key role for its conductivity and selective permeability.

Decoupling of size and shape fluctuations in heteropolymeric sequences reconciles discrepancies in SAXS vs. FRET measurements.

Unfolded states of proteins and native states of intrinsically disordered proteins (IDPs) populate heterogeneous conformational ensembles in solution. The average sizes of these heterogeneous systems, quantified by the radius of gyration (RG ), can be measured by small-angle X-ray scattering (SAXS). Another parameter, the mean dye-to-dye distance (RE ) for proteins with fluorescently labeled termini, can be estimated using single-molecule Förster resonance energy transfer (smFRET). A number of studies have reported inconsistencies in inferences drawn from the two sets of measurements for the dimensions of unfolded proteins and IDPs in the absence of chemical denaturants. These differences are typically attributed to the influence of fluorescent labels used in smFRET and to the impact of high concentrations and averaging features of SAXS. By measuring the dimensions of a collection of labeled and unlabeled polypeptides using smFRET and SAXS, we directly assessed the contributions of dyes to the experimental values RG and RE For chemically denatured proteins we obtain mutual consistency in our inferences based on RG and RE , whereas for IDPs under native conditions, we find substantial deviations. Using computations, we show that discrepant inferences are neither due to methodological shortcomings of specific measurements nor due to artifacts of dyes. Instead, our analysis suggests that chemical heterogeneity in heteropolymeric systems leads to a decoupling between RE and RG that is amplified in the absence of denaturants. Therefore, joint assessments of RG and RE combined with measurements of polymer shapes should provide a consistent and complete picture of the underlying ensembles.

An Interesting Case of Life-Threatening Hypercalcemia Secondary to Atypical Parathyroid Adenoma versus Parathyroid Carcinoma.

Context. Severe hypercalcemia is a life-threatening condition. Atypical parathyroid adenoma and parathyroid carcinomas are uncommon causes which can be difficult to differentiate. Objective. We report a case of a 36-year-old male with very high serum calcium due to a possible atypical parathyroid adenoma versus parathyroid carcinoma. Case Illustration. A serum calcium level of 23.2 mg/dl was noted on admission. He was initially treated with IV hydration, pamidronate, and salmon calcitonin to lower his calcium levels. He also underwent a surgical en bloc resection of parathyroid mass. Pathology showed a mixed picture consistent with possible atypical adenoma versus parathyroid carcinoma. However, due to the possible involvement of the recurrent laryngeal nerve, parathyroid carcinoma was more likely. Also after operation the patient developed hungry bones syndrome and his calcium was replaced vigorously. He continues to be on calcium, vitamin D, and calcitriol supplementation. Results. A review of the literature was conducted to identify previous studies pertaining to parathyroid adenomas and parathyroid cancer. Conclusion. We thereby conclude that hypercalcemia requires very careful monitoring especially after operation. Also it can be very difficult to distinguish between atypical parathyroid adenomas and parathyroid carcinomas as in our case and no clear cut guidelines yet exist to differentiate the two based on histology.

Influence of surface polarity on water dynamics at the water/rutile TiO2(110) interface.

We report molecular dynamics (MD) simulations of the water/clean rutile TiO2 (110) interface using polarizable and non-surface polarity force field models. The effect of surface polarity on the water dynamics near the TiO2(110) surface is addressed, specifically by calculating the water hydrogen bond and reorientational dynamics. The hydrogen bond lifetime of interfacial water molecules is several times longer than that of bulk water due to the strong water-TiO2 interactions. A comparison of the dynamics simulated with the polarizable and non-surface polarity models shows that, while the hydrogen bond lifetime between the interfacial water and TiO2 surface is insensitive to the surface polarity, the reorientational dynamics around this hydrogen bond axis is significantly influenced by the surface polarity; the surface polarity of the TiO2 increases the water-TiO2 interactions, stabilizing the local structure of the interfacial water molecules and restricting their rotational motion. This reorientation occurs predominantly by rotation around the O-H group hydrogen bonded to the TiO2 surface. Furthermore, we correlate the dynamics of the induced charge on the TiO2 surface with the interfacial water dynamics. Our results show that the timescale of correlations of the atom charges induced by the local electric field in bulk water is influenced by the rotational motion, hydrogen bond rearrangement and translational motion, while the induced charge dynamics of the TiO2 surface is governed primarily by the rotational dynamics of the interfacial water molecules. This study demonstrates that the solid surface polarity has a significant impact on the dynamics of water molecules near TiO2 surfaces.