From Bite to Byte: Dental Structures Resolved at a Single-Cell Resolution.

The systematic classification of the cells that compose a tissue or an organ is key to understanding how these cells cooperate and interact as a functional unit. Our capacity to detect features that define cell identity has evolved from morphological and chemical analyses, through the use of predefined genetic markers, to unbiased transcriptomic and epigenetic profiling. The innovative technology of single-cell RNA sequencing (scRNA-seq) enables transcriptional profiling of thousands of individual cells. Since its development, scRNA-seq has been extensively applied to numerous organs and tissues in a wide range of animal models and human samples, thereby providing a plethora of fundamental biological insights into their development, homeostasis, and pathology. In this review, we present the findings of 3 recent studies that employed scRNA-seq to unravel the complexity of cellular composition in mammalian teeth. These findings offer an unprecedented catalogue of cell types in the mouse incisor, which is a convenient model system for studying continuous tooth growth. These studies identified novel cell types in the tooth epithelium and mesenchyme, as well as new markers for known cell types. Computational analyses of the data also uncovered the lineage and dynamics of cell states during ameloblast and odontoblast differentiation during both normal homeostasis and injury repair. The transcriptional differences between the mouse incisor and mouse and human molars uncover species-specific as well as shared features in tooth cell composition. Here, we highlight these findings and discuss important similarities and differences between these studies. We also discuss potential future applications of scRNA-seq in dental research and dentistry. Together, these studies demonstrate how the rapidly evolving technology of scRNA-seq can advance the study of tooth development and function and provide putative targets for regenerative approaches.

IRF6 and SPRY4 Signaling Interact in Periderm Development.

Rare mutations in IRF6 and GRHL3 cause Van der Woude syndrome, an autosomal dominant orofacial clefting disorder. Common variants in IRF6 and GRHL3 also contribute risk for isolated orofacial clefting. Similarly, variants within genes that encode receptor tyrosine kinase (RTK) signaling components, including members of the FGF pathway, EPHA3 and SPRY2, also contribute risk for isolated orofacial clefting. In the mouse, loss of Irf6 or perturbation of Fgf signaling leads to abnormal oral epithelial adhesions and cleft palate. Oral adhesions can result from a disruption of periderm formation. Here, we find that IRF6 and SPRY4 signaling interact in periderm function. We crossed Irf6 heterozygous ( Irf6+/-) mice with transgenic mice that express Spry4 in the basal epithelial layer ( TgKRT14::Spry4). While embryos with either of these mutations can have abnormal oral adhesions, using a new quantitative assay, we observed a nonadditive effect of abnormal oral epithelial adhesions in the most severely affected double mutant embryos ( Irf6+/-;TgKRT14::Spry4). At the molecular level, the sites of abnormal oral adhesions maintained periderm-like cells that express keratin 6, but we observed abnormal expression of GRHL3. Together, these data suggest that Irf6 and RTK signaling interact in regulating periderm differentiation and function, as well as provide a rationale to screen for epistatic interactions between variants in IRF6 and RTK signaling pathway genes in human orofacial clefting populations.

Color Doppler imaging study in patients with primary open-angle glaucoma treated with timolol 0.5% and carteolol 2%.

PURPOSE: To evaluate with color Doppler imaging (CDI), in patients with primary open-angle glaucoma (PDAG), the possible influence on ocular hemodynamics of a beta-blocking agent with intrinsic sympathomimetic acitivity (carteolol 2%) compared to a beta-blocker agent without this activity. METHODS: A study was carried out on 20 patients, with bilateral POaG, intraocular pressure (IOP) < or = 20 mmHg, all treated twice a day with timolol maleate 0.5% ophthalmic solution. The visual field was evaluated (Octopus 2000 perimeter, G1 program) examining the mean sensitivity (MS) and the mean defect (MD). CDI was carried out to evaluate the resistance index of the internal carotid artery (ICA), the ophthalmic artery (OA), the central retinal artery (CRA), and the short posterior ciliary arteries (SPCA). After these examinations, the therapy was changed to carteolol 2% twice a day. After six months of treatment the examinations were repeated. The data were analysed statistically using Student's t test. RESULTS: The mean intraocular pressure during treatment with timolol 0.5% was 16.7 +/- 1.67 mmHg and 16.33 +/- 1.72 mmHg after treatment with carteolol 2%, the difference not being significant (p=0.494). After six months of treatment with carteolol 2% the MS increased significantly from 22.4 +/- 2.5 dB to 24.1 +/- 1.8 dB (p=0.018), and the mean defect (MD) fell from 5.3 +/- 0.8 dB to 4.7 +/- 0.6 dB (p=0.011). There was no significant difference in the resistance index of the CA, the OA and the CRA with the two treatments, whereas the resistance index of the SPCA dropped significantly, from 0.80 +/- 0.05 to 0.77 +/- 0.02 (p = 0.017). CONCLUSIONS: CDI did not show significant differences in the resistance indexes of the internal CA, the OA, and the CRA after treatment with carteolol 2% but the resistance index of the SPCA was significantly reduced. Carteolol 2% induced significant changes in the perimetric indexes examined, with an increase in MS and a decrease in MD. These findings suggest that the intrinsic sympathomimetic activity of carteolol may reduce peripheral vascular resistance of the SCA, thus improving perfusion of the optic nerve head, with a protective effect on visual function.

Brain auditory activation measured by near-infrared spectroscopy (NIRS) in neonates.

This study presents a new measure of the hemodynamic changes to an auditory stimulus in newborns. Nineteen newborns born at 28-41 wk and aged 1 to 49 d were studied in waking and/or sleeping state, for a median time of 4 min 40 s before, 2 min 40 s during, and 3 min 5 s after an acustic stimulus (tonal sweep of frequency increasing from 2 to 4 kHz, intensity 90 dB SPL) originating 5 cm from the external auditory meatus. The emitter and detector optodes were placed over the left or right temporal region, corresponding to T3 or T4 EEG electrodes. The concentration changes in cerebral chromophores Delta[HbO2], Delta[Hb] and Deltaoxidized-reduced cytochrome aa(3) were recorded every 5 s. Changes in cerebral blood volume were calculated from the changes in total Hb x 0.89/large vessel Hb concentration. Increased oxyhemoglobin, Delta[HbO2], total Hb, Delta[Hb (sum)], and cerebral blood volume, DeltaCBV, were found in 13/19 neonates, with the exception of a neonate who only had increased in Delta[Hb], Delta[Hb (sum)] and DeltaCBV. During the stimulation phase there was a significant increase in DeltaCBV (t test, p = 0.00006) in the responsive newborns from a mean value of 0.006 (+/-0.02) mL/100 g in the pretest phase to 0.09 (+/-0.06) mL/100 g during the auditory stimulus. After the test DeltaCBV decreased to 0.04 (+/-0.07) mL/100 g (t test, p = 0.01), so did Delta[Hb (sum)] (p = 0.02). Hemodynamic responses of the subjects who showed increases in Delta[Hb (sum)] and Delta[HbO(2)] were analyzed to study the Delta[Hb]. The responder subjects could be classified into two groups according to Delta[Hb] changes: 8/13 (61.5%) showed an increase of Delta[Hb] (pattern A), while 5/13 (38.4%) showed a decrease (pattern B) (t test, p = 0.03). These two patterns did not show differences related to Delta[HbO(2)] and Delta[Hb (sum)]. The DeltaCBV changes in nonresponders presented a decrease during the test phase (t test, p = 0.04). CBV did not return to pretest values, suggesting a fronto-temporal brain pathway for storing unusual sounds. The increase in CBV followed the local increase in oxyhemoglobin and total Hb concentrations due to a greater use of oxygen in the homolateral temporal cortex of the newborns.

Langerhans' cell histiocytosis: report of a case with temporal localization.

The authors report a case of Langerhans' cell histiocytosis (LCH) with temporal localization and rapidly evolving initial clinical presentation in a 12-year-old boy. This disease of currently unknown etiology is actually considered a proliferative entity of cells with phenotypic characteristics of normal Langerhans' cells. An immunoregulation defect leading to abnormal maturation and migration of Langerhans' cells might be the basis for LCH. According to the Hystiocyte Society diagnostic criteria, ATPase, S 100 and D-mannoxidase positivity in addition to typical hystopathologic findings are sufficient for diagnosis of LCH. Head and neck localization of LCH occurs in about 70% of cases; males are more frequently affected than females, age at presentation varies from a few months to 15 years. Presenting features, initial diagnostic evaluation, differential diagnosis and treatment protocol of a unifocal monosystemic temporal bone localization of LCH are presented.

Glaucoma after vitreo-retinal surgery with silicone oil injection: epidemiologic aspects.

PURPOSE: To evaluate the prevalence of glaucoma after pars plana vitrectomy with silicone oil injection and to determine the different clinical forms. METHODS: Authors have carried out a retrospective longitudinal study on patients who underwent pars plana vitrectomy with silicone oil injection from 1981 to 1995. The examined population consists of 301 patients (301 eyes), with an age ranging from 8 to 85 years, affected by retinal detachment and proliferative vitreoretinopathy. RESULTS: The prevalence of the secondary glaucoma has been 18.5%. In all cases glaucoma was caused by trabecular meshwork obstruction due to silicone oil emulsification. The glaucoma has been more frequent after surgery for recurrent rhegmatogenous retinal detachment with fibrous PVR (52.86%) and for particular forms of rhegmatogenous retinal detachment (giant tears, multiple breaks, pseudophakia) with incipient PVR (30%). CONCLUSION: Glaucoma after intravitreal silicone oil injection for complicated retinal detachments is a relatively frequent complication mostly when surgery needs endophotocoagulation, endodiatermy and lensectomy.

Terminal deletion of the short arm of chromosome 5.

Three cases of deletion of the short arm of chromosome 5 are described: one family cluster, in which the mother and three sons are affected, and two sporadics without the typical "cri du chat" phenotype (the family and Case 2 were previously reported in 1982). Mental retardation varied between affected members of the same family. Band p15.2 appears critical for the development of the complete phenotype. A peculiar deafness observed in the familial and one of the sporadic cases suggests a cochlear malformation.

[A comparative study of T Cu-200 insertions by medical doctors and midwives]. / Estudio comparativo de inserciones de la TCu-200 hechas por medicos y obstetrices.

PIP: The Asociacion Pro Bienestar de la Familia Ecuadoriana has employed since 1965 midwives to perform clinical services. This comparative study investigates 310 insertions of T Cu-200 done by physicians, and 297 insertions of the same IUD type done by midwives. Age and parity of acceptors were comparable in both groups. Insertions were executed by midwives with as much skill and knowledge as the doctors, and termination rates for medical reasons were almost similar in both groups. Several authors have confirmed the fact that experienced midwives can be successfully trained in performing IUD insertions.^ieng