Assessment of clinical validity of KPG index for 3D classification of impacted maxillary canines by cone beam computed tomography in patients

OBJECTIVES

The primary objective of this study was to assess the validity of the KPG index in predicting the difficulty of treatment involving impacted maxillary canines. The secondary objective was to assess the reliability and reproducibility of the index.

MATERIALS AND METHODS

A retrospective study was conducted on 96 maxillary impacted canines (MIC) in 60 patients aged 13-35 years. Cone-beam computed tomography (CBCT) scans were used to predict the treatment difficulty of MIC using the KPG index. Patient case files were assessed for the actual difficulty encountered in treating MIC. Cohen's kappa correlation coefficient was used for intra-observer reliability and Kendell's W test was used for inter-observer reliability. Spearman's correlation coefficient test was used to assess the correlation between predicted and actual treatment.

RESULTS

Easy and moderately difficult cases exhibited a moderate correlation between actual and predicted treatment outcomes, whereas difficult cases displayed a weak correlation. The perfect correlation was observed exclusively in extremely difficult cases. The intra-observer reliability for assessing CBCT scans using the KPG guide was found to be 0.88, and the inter-rater reliability was 0.94.

CONCLUSION

The KPG index displayed 87%, 71%, 50% and 100% validity in easy, moderately difficult, difficult, and extremely difficult cases, respectively. This index showed good reliability and reproducibility. However, it is imperative to consider a multitude of other factors, including the patient's age, presence of associated root resorption in adjacent teeth, and duration of treatment, to make an informed decision between surgical exposure and extraction.

Quantifying plasmonic characteristics of pure and alkali doped aluminium clusters

Study of plasmonic response of molecules and metal nanoclusters have drawn a considerable attention during recent times due to their various practical applications. In this study, the optical properties and the plasmonic response of our recently reported Al13+ cluster [Guin et al. Journal of Molecular Graphics and Modelling, 2020, 97, 107544] and its alkali doped counterparts [Guin et al. Journal of Molecular Modeling, 2021, 27, 235] have been investigated based on Transition dipole moment (TDM), Natural Transition Orbital (NTO) and transition inverse participation ratio (TIPR) indices. Recently these indices have been utilized by various scientists to characterize plasmonic transitions of molecular systems and metal nanoclusters. In TDM analysis, the magnitude of all the contributing TDMs associated with the molecular orbital transitions have been estimated along with the angles the individual dipoles make with the resultant dipole moment vector. A transition having at least two dominating TDM contributions along with phase matching indicate a collective or plasmonic transition. The collectiveness of orbital transitions is also corroborated through NTO and TIPR analysis. The effect of solvent medium on the optical properties and plasmonic transitions have also been studied using time dependent density functional theory in the conductor like polarizable continuum model (TDDFT-CPCM). The solvent has a strong impact on the optical properties as well as the plasmonic response of the clusters. The dielectric environment of the solvent red shifts and broadens the spectra with respect to that in the gas phase. Plasmon like excitations have been found for Li doped Al13+ cluster without solvent and Na doped Al13+ cluster in ethanol and THF.

Electric field-driven up-and-down motion of the flexible tail of Al13+ cluster system-a nano-scale flipper

CONTEXT

Dynamic metal nanoclusters have become a hot area of research in the field of nanoscience and nanotechnology due to their potential applications in micro devices. One such dynamic cluster is a quasi-planar ground state (GS) Al13+ cluster which exhibits an electric field driven up and down flipping motion of the flexible tail which oscillates with respect to the mean plane. A Car-Parrinello molecular dynamics (CPMD) simulation has been carried out to understand the nature of dynamics of the cluster. CPMD simulation study reveals that the flexible tail region of the Al13+ isomeric system (two ground states M1, M2 and a transition state TS connecting them) can be engaged in a systematic up down flipping motion by the application of a transverse electric field. A saw tooth electric field of amplitude 5.19 V/nm is sufficient to induce the up-and-down flipping oscillation of the cluster, which has an average oscillation frequency of around 20 THz. AIM, NICS and AdNDP analyses also have been carried out to understand the fluxional nature of the cluster from the electronic structural perspective. Electronic structural analysis of selected optimized intermediate states in the presence of transverse electric field has also been analyzed to correlate the electronic structure with the dynamic nature of the cluster.

METHODS

Single-point energies of all intermediate states between two minima of Al13+ clusters connected through a transition state cluster. Optimized geometries of Al13+ clusters in the presence of electric field of different strengths have been carried out by using the Gaussian 03 package. 6-311 + G(d) basis set and B3LYP hybrid density functional have been utilized for these studies. To establish the flipping motion, Car-Parrinello molecular dynamics (CPMD) has been performed using the cp.x module of the Quantum ESPRESSO 6.3.0 program package using the Perdew-Burke-Ernzerhof (PBE) functional, plane-wave basis set and ultrasoft pseudopotentials. ORTEP-3 and POV ray-3.7 software packages have been used for visualization and graphics generation. Atoms in molecule (AIM), Adaptive Natural Density Partitioning (AdNDP) analysis have been carried out using Multiwfn 3.7 program package.

Effect of alkali atom doping on the electronic structure and aromatic character of planar and quasi-planar Al13+ clusters

A set of three Al₁₃⁺ clusters, one perfectly planar, and two quasi-planar structures, have been recently reported by our group (Guin et al. Journal of Molecular Graphics and Modeling, 2020, 97, 107544). All three clusters possess bilateral symmetry with identical structural features-a set of ten aluminum atoms encircle a triangular core. The symmetry axis passes through one of the Al atoms of the central triangular core and two Al atoms located on the periphery at two opposite ends of the cluster. This set of three aluminum clusters is an example of a rare metallo-aromatic system where highly anti-aromatic islands are embedded within an aromatic sea. In the present study, we have explored the effect of doping alkali atoms (Li, Na, and K) at the positions of the Al atoms that lie on the symmetry axis of the cluster intending to understand the structural stability and the effect on the aromatic character as compared to the undoped parent clusters. Besides the electronic structural analysis, NICS and ELF studies have also been carried out to characterize the aromatic nature of the doped clusters. Interestingly, it has been found that even with the incorporation of the alkali atoms, the bilateral symmetry of the clusters remains intact, but the alkali atoms are pushed out of the original location toward the edge of the cluster, whereas the aluminum atoms remain grouped. The dipole moment of the clusters systematically increases, and the overall aromaticity of the cluster systematically decreases with the increase in the atomic number of the doped alkali atoms. Effect of alkali atom doping to Al₁₃⁺ cluster.

Metal–ligand ring aromaticity in a 2D coordination polymer used as a photosensitive electronic device

14-Membered metal–ligand ring present in a photosensitive 2D coordination polymer, [Zn₂(fum)₂(4-phpy)₄(H₂O)₂] (H₂fum = fumaric acid and 4-phpy = 4-phenyl pyridine) shows aromatic character as evident by the nucleus-independent chemical shifts (NICS) calculation.

Culture-independent real-time PCR reveals extensive polymicrobial infections in hospitalized diarrhoea cases in Kolkata, India

Culture-independent identification of diarrhoeal aetiological agents was performed using DNA harvested from diarrhoeal stool specimens with SYBR-Green-based real-time PCR targeting Vibrio cholerae, Vibrio parahaemolyticus, Campylobacter spp., Shigella spp. and three different pathotypes of diarrhoeagenic Escherichia coli. Conventional culture-dependent methods detected bacterial enteropathogens in 68 of 122 diarrhoeal stool specimens. Of 68 specimens, 59 (86.8%) had a single pathogen and the remaining nine (13.2%) had polymicrobial infections with multiple pathogens. Re-analysis of the 68 specimens by culture-independent real-time PCR methods showed that 25 (36.8%) specimens contained single pathogen and 43 (63.2%) specimens contained mixed infections with multiple pathogens. The prevalence of such high levels of polymicrobial infections would not have been detected without using real-time PCR. Culture-dependent analysis assigned 54 of the 122 selected archived specimens as 'no known aetiology'. However, re-analysis of these samples by real-time PCR showed the presence of single or multiple pathogens among 34 (63%) of these specimens. Estimation of relative pathogen load by real-time PCR in the stool specimens indicated that the inability of conventional culture-dependent methods to detect the pathogens was related to lower colony-forming units of the pathogen, as reflected by lower C(t) values. Detection of high levels of polymicrobial infection by real-time PCR indicates that in the settings like Kolkata and its surroundings, where cholera and other enteric diseases are endemic, the concept of one pathogen one disease might need to be re-evaluated.

Thyroid hormone induces the generation of a novel putative protein in piscine ovarian follicle that stimulates the conversion of pregnenolone to progesterone

Ovarian follicles were collected from the perch belonging to the vitellogenic stage and incubated in vitro for 4 h in the absence (control) or presence of triiodothyronine (T3). Addition of T3 (40 ng/ml) to the follicle incubation caused a two-fold increase of [3H] pregnenolone conversion to radiolabelled progesterone (P4) as compared to the control. The increase in P4 formation in the ovarian follicle could be blocked completely by the inhibitors of protein synthesis, actinomycin D and cycloheximide (50 micrograms/ml), suggesting a protein or peptide mediator of the T3 stimulatory effect. To search for this mediator, ovarian follicles from the control or T3 incubate were homogenized and ultracentrifuged and different fractions were added separately to fresh follicle incubations. Only the 100,000 g supernatant from T3 incubate showed a significant (p < 0.01) increase in P4 formation, while the corresponding supernatant from control follicle incubations had no such stimulatory effect. Trypsin or heat destroyed this augmentory effect. Based on its ability to stimulate the conversion of radiolabelled pregnenolone to P4 in the ovarian follicle, the T3-induced protein (TIP) was purified to homogeneity by employing Sephadex G-75 gel filtration, FPLC Mono-Q and FPLC Superose-6 chromatography. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of purified TIP showed it to be a 52 K monomer protein. Addition of TIP in increasing concentrations to follicle incubations caused a linear increase in P4 formation. Experiments with radiolabelled TIP ([125I] TIP) indicate its entry through the follicular cell membrane within the limited period of incubation. Results suggest that TIP activates ovarian 3 beta-hydroxysteroid dehydrogenase enzyme, thus effecting a greater conversion of pregnenolone to P4.