Research Spotlight

Li, C., Liu, S., Mei, Y., Wang, Q., Lu, X., Li, H. and Tao, F. (2022). “Differential Effects of Sevoflurane Exposure on Long-Term Fear Memory in Neonatal and Adult Rats.” Mol Neurobiol.

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It remains unclear whether exposure to sevoflurane produces different effects on long-term cognitive function in developing and mature brains. In the present study, Sprague-Dawley neonatal rats at postnatal day (PND) 7 and adult rats (PND 56) were used in all experiments. We performed fear conditioning testing to examine long-term fear memory following 4-h sevoflurane exposure. We assessed hippocampal synapse ultrastructure with a transmission electron microscope. Moreover, we investigated the effect of sevoflurane exposure on the expression of postsynaptic protein 95 (PSD-95) and its binding protein kalirin-7 in the hippocampus. We observed that early exposure to sevoflurane in neonatal rats impairs hippocampus-dependent fear memory, reduces hippocampal synapse density, and dramatically decreases the expressions of PSD-95 and kalirin-7 in the hippocampus of the developing brain. However, sevoflurane exposure in adult rats has no effects on hippocampus-dependent fear memory and hippocampal synapse density, and the expressions of PSD-95 and kalirin-7 in the adult hippocampus are not significantly altered following sevoflurane treatment. Our results indicate that sevoflurane exposure produces differential effects on long-term fear memory in neonatal and adult rats and that PSD-95 signaling may be involved in the molecular mechanism for early sevoflurane exposure-caused long-term fear memory impairment.

Revilla-León, M., Gohil, A., Barmak, A. B., Gómez-Polo, M., Pérez-Barquero, J. A., Att, W. and Kois, J. C. (2022). “Influence of ambient temperature changes on intraoral scanning accuracy.” J Prosthet Dent.

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STATEMENT OF PROBLEM: Different variables that decrease the accuracy of intraoral scanners (IOSs) have been identified. Ambient temperature changes can occur in the dental environment, but the impact of ambient temperature changes on intraoral scanning accuracy is unknown. PURPOSE: The purpose of this in vitro study was to assess the impact of ambient temperature changes on the accuracy (trueness and precision) of an IOS. MATERIAL AND METHODS: A complete arch maxillary dentate Type IV stone cast was obtained. Four 6-mm-diameter gauge balls were added to the maxillary cast to aid future evaluation measurements. The maxillary cast was digitized by using an industrial scanner (GOM Atos Q 3D 12M). The manufacturer’s recommendations were followed in obtaining a reference scan. Then, the maxillary cast was digitized by using an IOS (TRIOS 4) according to the scanning protocol recommended by the manufacturer. Four groups were created depending on the ambient temperature change assessed: 24 °C or room temperature (24-D or control group), 19 °C or a 5-degree temperature drop (19-D group), 15 °C or a 9-degree temperature drop (15-D group), and 29 °C or a 5-degree temperature rise (29-D group). The Shapiro-Wilk and Kolmogorov-Smirnov tests revealed that the data were not normally distributed (P<.05). For trueness, the nonparametric Kruskal-Wallis followed by the Dwass-Steel-Critchlow-Fligner pairwise comparison tests were used. Precision analysis was obtained by using the Levene test based on the comparison of the standard deviations of the 4 groups with 95% Bonferroni confidence intervals for standard deviations (α=.05). RESULTS: The Kruskal-Wallis test revealed significant differences in the trueness values among all 4 groups (P<.001). Furthermore, significant differences between the linear discrepancy medians between the control and 19-D groups (P<.001), control and 15-D groups (P=.002), control and 29-D groups (P<.001), 19-D and 29-D groups (P=.003), and 15-D and 29-D groups (P<.001) were found. The Levene test for the comparison of the variances among the 4 groups did not detect a significant difference (P=1.000), indicating that precision wise the 4 groups were not significantly different from each other. CONCLUSIONS: Ambient temperature changes had a detrimental effect on the accuracy (trueness and precision) of the IOS tested. Ambient temperature changes significantly decreased the scanning accuracy of the IOS system tested. Increasing the ambient temperature has a greater influence on the intraoral scanning accuracy of the IOS selected when compared with decreasing the ambient temperature.

Quick, K. K., Horvath, Z., Danciu, T. E., Dehghan, M., Godley, L. W. and Kabani, F. A. (2022). “Scenario I: Opportunity lost.” J Dent Educ 86(3): 352-355.

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In this scenario, academic dentistry is blessed with a strengthened financial position over the next five years, but educational innovation loses momentum after the COVID-19 pandemic. Tradition wins over innovation and prevents the growth and sustainability of initiatives precipitated by the pandemic.

Kaplan, F. S., Groppe, J. C., Xu, M., Towler, O. W., Grunvald, E., Kalunian, K., Kallish, S., Al Mukaddam, M., Pignolo, R. J. and Shore, E. M. (2022). “An ACVR1(R375P) pathogenic variant in two families with mild fibrodysplasia ossificans progressiva.” Am J Med Genet A 188(3): 806-817.

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Genetic variants are vital in informing clinical phenotypes, aiding physical diagnosis, guiding genetic counseling, understanding the molecular basis of disease, and potentially stimulating drug development. Here we describe two families with an ultrarare ACVR1 gain-of-function pathogenic variant (codon 375, Arginine > Proline; ACVR1(R375P) ) responsible for a mild nonclassic fibrodysplasia ossificans progressiva (FOP) phenotype. Both families include people with the ultrarare ACVR1(R375P) variant who exhibit features of FOP while other individuals currently do not express any clinical signs of FOP. Thus, the mild ACVR1(R375P) variant greatly expands the scope and understanding of this rare disorder.

Wang, J., Jiang, Y., Xie, X., Zhang, S., Xu, C., Zhou, Y. and Feng, J. Q. (2022). “The identification of critical time windows of postnatal root elongation in response to Wnt/β-catenin signaling.” Oral Dis 28(2): 442-451.

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OBJECTIVES: In this study, we attempted to define the precise window of time for molar root elongation using a gain-of-function mutation of β-catenin model. MATERIALS AND METHODS: Both the control and constitutively activated β-catenin (CA-β-cat) mice received a one-time tamoxifen administration (for activation of β-catenin at newborn, postnatal day 3, or 5, or 7, or 9) and were harvested at the same stage of P21. Multiple approaches were used to define the window of time of postnatal tooth root formation. RESULTS: In the early activation groups (tamoxifen induction at newborn, or P3 or P5), there was a lack of molar root elongation in the CA-β-cat mice. When induced at P7, the root length was slightly reduced at P21. However, the root length was essentially the same as that in the control when β-cat activated at P9. This study indicates that root elongation occurs in a narrow time of window, which is highly sensitive to a change of β-catenin levels. Molecular studies showed a drastic decrease in the levels of nuclear factor I-C (NFIC) and osterix (OSX), plus sharp reductions of odontoblast differentiation markers, including Nestin, dentin sialoprotein (DSP), and dentin matrix protein 1 (DMP1) at both mRNA and protein levels. CONCLUSIONS: Murine molar root elongation is precisely regulated by the Wnt/β-catenin signaling within a narrow window of time (newborn to day 5).