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1.
Radiat Prot Dosimetry ; 198(17): 1283-1291, 2022 Oct 01.
Article de Anglais | MEDLINE | ID: mdl-35876638

RÉSUMÉ

The crystal configuration dependence of thallium-doped caesium iodide (CsI(Tl)) scintillation detectors was analysed on an ambient dose equivalent (H*(10)). H*(10) were systematically calculated in various crystal conditions for aspect ratios and sizes in a virtual environment contaminated by radionuclides to investigate directional characteristics by comparing the H*(10)s with the typical irradiation geometries in anterior-posterior (AP), lateral (LAT), rotational (ROT) and isotropic (ISO). The simulation revealed that H*(10) obviously changes according to the crystal configuration and cuboidal CsI(Tl) scintillation detectors with specific aspect ratios could be applied to environmental dose rate measurement without further changes in the calibration procedure.


Sujet(s)
Radio-isotopes , Thallium , Calibrage , Simulation numérique , Comptage de scintillations
2.
Field Crops Res ; 281: 108503, 2022 May 15.
Article de Anglais | MEDLINE | ID: mdl-35582149

RÉSUMÉ

Increasing fertilizer access and use is an essential component for improving crop production and food security in sub-Saharan Africa (SSA). However, given the heterogeneous nature of smallholder farms, fertilizer application needs to be tailored to specific farming conditions to increase yield, profitability, and nutrient use efficiency. The site-specific nutrient management (SSNM) approach initially developed in the 1990 s for generating field-specific fertilizer recommendations for rice in Asia, has also been introduced to rice, maize and cassava cropping systems in SSA. The SSNM approach has been shown to increase yield, profitability, and nutrient use efficiency. Yield gains of rice and maize with SSNM in SSA were on average 24% and 69% when compared to the farmer practice, respectively, or 11% and 4% when compared to local blanket fertilizer recommendations. However, there is need for more extensive field evaluation to quantify the broader benefits of the SSNM approach in diverse farming systems and environments. Especially for rice, the SSNM approach should be expanded to rainfed systems, which are dominant in SSA and further developed to take into account soil texture and soil water availability. Digital decision support tools such as RiceAdvice and Nutrient Expert can enable wider dissemination of locally relevant SSNM recommendations to reach large numbers of farmers at scale. One of the major limitations of the currently available SSNM decision support tools is the requirement of acquiring a significant amount of farm-specific information needed to formulate SSNM recommendations. The scaling potential of SSNM will be greatly enhanced by integration with other agronomic advisory platforms and seamless integration of digital soil, climate and crop information to improve predictions of SSNM recommendations with reduced need for on-farm data collection. Uncertainty should also be included in future solutions, primarily to also better account for varying prices and economic outcomes.

3.
Rev Sci Instrum ; 93(4): 043506, 2022 Apr 01.
Article de Anglais | MEDLINE | ID: mdl-35489959

RÉSUMÉ

Ion cyclotron resonance heating (ICRH), one of the main auxiliary methods, for high-power and long-pulse plasma heating had been developed in Experimental Advanced Superconducting Tokamak (EAST). An impedance matching system, one important part of ICRH, had been developed for high-power injection and transmitter protection by reducing the reflected power from the antenna. The input impedance in the outlet of the stub tuner can be measured by voltage-current probes installed on the coaxial transmission line between the antenna and triple liquid stub tuners, and the optimum liquid levels in the stub tuners can be calculated based on the input impedance. The calculation and adjustment process of the optimum liquid levels are described comprehensively in this article. Finally, impedance matching had been achieved between two shots during EAST experiments. In the near future, a real-time impedance matching system will be developed to prevent large variations of the ICRH antenna impedance and achieve steady-state and long-pulse operation with the ICRH system.

4.
Anticancer Res ; 42(1): 173-183, 2022 Jan.
Article de Anglais | MEDLINE | ID: mdl-34969723

RÉSUMÉ

AIM: We evaluated real-world efficacy and toxicity of lenvatinib in 142 patients with advanced hepatocellular carcinoma (HCC) at six tertiary referral centres. PATIENTS AND METHODS: The patients with advanced HCC treated with lenvatinib were grouped into two categories based on REFLECT criteria for analysis of efficacy and safety. The primary endpoint was progression-free survival (PFS). RESULTS: The objective response rate (ORR) at week 12 of therapy was 41.5%, with a median PFS of 176 days. Child-Pugh score of 5 points, the presence of extrahepatic metastasis and adverse effects grade 2 or higher were considered independent factors associated with both better PFS and ORR. The ORR for patients who fulfilled the REFLECT inclusion criteria was significantly higher than that for those who did not. However, no significant differences in PFS were observed between the two groups. The incidence rate of adverse effects grade 3 or higher was 40.1%, which was similar for the two groups. CONCLUSION: Lenvatinib is safe and effective for patients, whether or not they satisfy REFLECT criteria. The result warrants replication in a larger study.


Sujet(s)
Carcinome hépatocellulaire/traitement médicamenteux , Tumeurs du foie/traitement médicamenteux , Phénylurées/administration et posologie , Inhibiteurs de protéines kinases/administration et posologie , Quinoléines/administration et posologie , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Antinéoplasiques/administration et posologie , Antinéoplasiques/analyse , Biomarqueurs pharmacologiques/métabolisme , Carcinome hépatocellulaire/épidémiologie , Carcinome hépatocellulaire/anatomopathologie , Femelle , Humains , Japon/épidémiologie , Tumeurs du foie/épidémiologie , Tumeurs du foie/anatomopathologie , Mâle , Adulte d'âge moyen , Phénylurées/effets indésirables , Survie sans progression , Inhibiteurs de protéines kinases/effets indésirables , Quinoléines/effets indésirables , Résultat thérapeutique
5.
J Eur Acad Dermatol Venereol ; 36(2): 295-304, 2022 Feb.
Article de Anglais | MEDLINE | ID: mdl-34699104

RÉSUMÉ

BACKGROUND: Loss-of-function homozygous or compound heterozygous mutations in IL36RN, which encodes interleukin-36 receptor antagonist (IL-36Ra), has been implicated in the pathogenesis of skin disorders. However, the pathogenic role of IL-36Ra in cutaneous ischemia-reperfusion (I/R) injury remains unclear. OBJECTIVES: We investigated the role of IL36Ra in cutaneous I/R injury. METHODS: We examined I/R injury in Il36rn-/- mice. The area of wounds, numbers of infiltrated cells, apoptotic cells and neutrophil extracellular trap (NET) formation were assessed. The expression levels of various genes were analysed using real-time RT-PCR. The expression of high mobility group box 1 (HMGB1), an endogenous toll-like receptor (TLR) 4 ligand, was confirmed using immunohistology, and serum HMGB1 levels were measured by ELISA. Cytokine production by stimulated cultured J774A.1 and HaCaT cells was examined. RESULTS: IL-36Ra deficiency resulted in significantly delayed wound healing and increased neutrophil and macrophage infiltration into the wound tissues. Il36rn-/- mice had increased mRNA expression levels of CXCL1, CXCL2, CCL4, TNF-α, TGF-ß, IL-1ß, IL-6 and IL-36γ relative to wild-type mice. Apoptosis was identified in keratinocytes by TUNEL assay. HMGB1 expression in the I/R site was decreased in both keratinocytes and adnexal cells, while serum HMGB1 levels were significantly elevated after reperfusion. The mRNA levels of various cytokines, including IL-1ß, were elevated in J774A.1 cells through TLR4 signalling by HMGB1 stimulation. In addition, HaCaT cells stimulated with IL-1ß showed significantly increased CXCL1, TNF-α, IL-6, IL-36ß and IL-36γ mRNA expression. Furthermore, NET formation was increased by IL-36Ra deficiency. Finally, either the blockade of TLR4 signalling by TAK-242 or inhibition of NET formation by Cl-amidine normalized exacerbated I/R injury in Il36rn-/- mice. CONCLUSIONS: This study indicated that IL-36Ra deficiency exacerbates cutaneous I/R injury due to excessive inflammatory cell recruitment, NET formation, and excessive cytokine and chemokine production via the TLR4 pathway by HMGB1 released from epidermal apoptotic cells.


Sujet(s)
Protéine HMGB1 , Lésion d'ischémie-reperfusion , Animaux , Cytokines , Protéine HMGB1/génétique , Protéine HMGB1/métabolisme , Macrophages/métabolisme , Souris , Lésion d'ischémie-reperfusion/génétique , Transduction du signal , Facteur de nécrose tumorale alpha
6.
J Dent Res ; : 220345211049785, 2021 Nov 20.
Article de Anglais | MEDLINE | ID: mdl-34806461

RÉSUMÉ

Organ development is dictated by the regulation of genes preferentially expressed in tissues or cell types. Gene expression profiling and identification of specific genes in organs can provide insights into organogenesis. Therefore, genome-wide analysis is a powerful tool for clarifying the mechanisms of development during organogenesis as well as tooth development. Single-cell RNA sequencing (scRNA-seq) is a suitable tool for unraveling the gene expression profile of dental cells. Using scRNA-seq, we can obtain a large pool of information on gene expression; however, identification of functional genes, which are key molecules for tooth development, via this approach remains challenging. In the present study, we performed cap analysis of gene expression sequence (CAGE-seq) using mouse tooth germ to identify the genes preferentially expressed in teeth. The CAGE-seq counts short reads at the 5'-end of transcripts; therefore, this method can quantify the amount of transcripts without bias related to the transcript length. We hypothesized that this CAGE data set would be of great help for further understanding a gene expression profile through scRNA-seq. We aimed to identify the important genes involved in tooth development via bioinformatics analyses, using a combination of scRNA-seq and CAGE-seq. We obtained the scRNA-seq data set of 12,212 cells from postnatal day 1 mouse molars and the CAGE-seq data set from postnatal day 1 molars. scRNA-seq analysis revealed the spatiotemporal expression of cell type-specific genes, and CAGE-seq helped determine whether these genes are preferentially expressed in tooth or ubiquitously. Furthermore, we identified candidate genes as novel tooth-enriched and dental cell type-specific markers. Our results show that the integration of scRNA-seq and CAGE-seq highlights the genes important for tooth development among numerous gene expression profiles. These findings should contribute to resolving the mechanism of tooth development and establishing the basis for tooth regeneration in the future.

7.
Radiat Prot Dosimetry ; 193(3-4): 228-236, 2021 May 17.
Article de Anglais | MEDLINE | ID: mdl-33893735

RÉSUMÉ

Ambient dose equivalent rates were measured in the environment of the Fukushima prefecture using NaI(Tl)/CsI(Tl) scintillation detectors and CdZnTe/Ge semiconductor detectors. The dose rates obtained at the same locations varied beyond uncertainty (1σ). By replacing the spectrum-dose conversion operators obtained from the anterior-posterior geometry with those from the rotational geometry, the dose rates agreed with each other within uncertainties, except for a CsI(Tl) scintillation detector with a considerably flat crystal configuration, due to its excessive directional dependence.


Sujet(s)
Polluants atmosphériques radioactifs , Contrôle des radiations , Radioactivité , Polluants atmosphériques radioactifs/analyse , Césium , Semiconducteurs
8.
Clin Radiol ; 76(2): 160.e15-160.e25, 2021 Feb.
Article de Anglais | MEDLINE | ID: mdl-33046228

RÉSUMÉ

AIM: To evaluate the clinicopathological and computed tomography (CT) and magnetic resonance imaging (MRI) findings of steatohepatitic hepatocellular carcinoma (SH-HCC). MATERIALS AND METHODS: Clinicopathological and radiological features were evaluated in 20 patients with SH-HCC. The diagnosis of SH-HCC was made histologically if the tumour had four of the following five characteristics: steatosis (>5% tumour cells), ballooning, Mallory-Denk bodies, interstitial fibrosis, and inflammation. All patients underwent dynamic CT and MRI. CT and MRI images were reviewed for morphological features including tumour size, presence, and distribution of fat, and patterns and degree of contrast enhancement. RESULTS: Obesity, hypertension, and history of heavy alcohol intake were common clinical findings observed in 10 (50%), 13 (65%), and 11 (55%) of the 20 patients, respectively. Steatosis and steatohepatitis were pronounced in the background liver in 12 (60%) and 10 (50%) patients, respectively. SH-HCC was moderately differentiated in 18 patients (90%) and well differentiated in two (10%). Pathologically, steatohepatitic features were diffuse in 12 (60%) of the 20 tumours and focal in eight (40%). Tumour size and the percentage of intratumoural steatosis were not correlated (r=0.17, p=0.47). On CT, 16 (80%) patients showed arterial phase enhancement and delayed washout. On MRI, 16 (80%) of 20 tumours showed prominent fatty deposition (10 diffusely, six focally) with arterial phase enhancement. CONCLUSIONS: SH-HCC is likely to show prominent fatty deposits with arterial phase enhancement on CT and MRI. A hypervascular lesion with prominent fatty change should raise the diagnostic suspicion of SH-HCC.


Sujet(s)
Carcinome hépatocellulaire/imagerie diagnostique , Stéatose hépatique/imagerie diagnostique , Tumeurs du foie/imagerie diagnostique , Imagerie par résonance magnétique/méthodes , Tomodensitométrie/méthodes , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Carcinome hépatocellulaire/complications , Carcinome hépatocellulaire/anatomopathologie , Stéatose hépatique/complications , Stéatose hépatique/anatomopathologie , Femelle , Humains , Foie/imagerie diagnostique , Foie/anatomopathologie , Tumeurs du foie/complications , Tumeurs du foie/anatomopathologie , Mâle , Adulte d'âge moyen
10.
Article de Anglais | MEDLINE | ID: mdl-32071052

RÉSUMÉ

This study was conducted in treatment-naive adults with drug-susceptible pulmonary tuberculosis in Port-au-Prince, Haiti, to assess the safety, bactericidal activity, and pharmacokinetics of nitazoxanide (NTZ). This was a prospective phase II clinical trial in 30 adults with pulmonary tuberculosis. Twenty participants received 1 g of NTZ orally twice daily for 14 days. A control group of 10 participants received standard therapy over 14 days. The primary outcome was the change in time to culture positivity (TTP) in an automated liquid culture system. The most common adverse events seen in the NTZ group were gastrointestinal complaints and headache. The mean change in TTP in sputum over 14 days in the NTZ group was 3.2 h ± 22.6 h and was not statistically significant (P = 0.56). The mean change in TTP in the standard therapy group was significantly increased, at 134 h ± 45.2 h (P < 0.0001). The mean NTZ MIC for Mycobacterium tuberculosis isolates was 12.3 µg/ml; the mean NTZ maximum concentration (Cmax) in plasma was 10.2 µg/ml. Negligible NTZ levels were measured in sputum. At the doses used, NTZ did not show bactericidal activity against M. tuberculosis Plasma concentrations of NTZ were below the MIC, and its negligible accumulation in pulmonary sites may explain the lack of bactericidal activity. (This study has been registered at ClinicalTrials.gov under identifier NCT02684240.).


Sujet(s)
Antituberculeux/pharmacocinétique , Antituberculeux/usage thérapeutique , Mycobacterium tuberculosis/effets des médicaments et des substances chimiques , Composés nitrés/pharmacocinétique , Composés nitrés/usage thérapeutique , Thiazoles/pharmacocinétique , Thiazoles/usage thérapeutique , Tuberculose pulmonaire/traitement médicamenteux , Adulte , Antituberculeux/effets indésirables , Femelle , Haïti , Humains , Mâle , Tests de sensibilité microbienne , Composés nitrés/effets indésirables , Expectoration/microbiologie , Thiazoles/effets indésirables , Jeune adulte
11.
Radiat Prot Dosimetry ; 184(3-4): 500-503, 2019 Oct 01.
Article de Anglais | MEDLINE | ID: mdl-31330022

RÉSUMÉ

Absorbed dose rates in air were measured for the whole area of the Kanto region in 2015, 2016 and 2017 (n = 31 147). The mean absorbed dose rates in air for each prefecture measured by car-borne surveys were from 44 to 67 nGy h-1 (13-289 nGy h-1). The absorbed dose rate in air from artificial radionuclides (134Cs + 137Cs) measured by fixed-point observation (n = 507) was from 1 to 14 nGy h-1 (0-105 nGy h-1), and meaning that the contribution ratios of 134Cs and 137Cs were 3-22%. The deposited location of artificial radionuclides was less than 1000 m from ground level and depended on the topography, wind direction and precipitation field.


Sujet(s)
Polluants atmosphériques radioactifs/analyse , Radio-isotopes du césium/analyse , Accident nucléaire de Fukushima , Centrales nucléaires , Contrôle des radiations/méthodes , Retombées radioactives/analyse , Humains , Japon , Dose de rayonnement
12.
Nat Commun ; 10(1): 2780, 2019 06 25.
Article de Anglais | MEDLINE | ID: mdl-31239441

RÉSUMÉ

In the developing central nervous system, cell departure from the apical surface is the initial and fundamental step to form the 3D, organized architecture. Both delamination of differentiating cells and repositioning of progenitors to generate outer radial glial cells (oRGs) contribute to mammalian neocortical expansion; however, a comprehensive understanding of their mechanisms is lacking. Here, we demonstrate that Lzts1, a molecule associated with microtubule components, promotes both cell departure events. In neuronally committed cells, Lzts1 functions in apical delamination by altering apical junctional organization. In apical RGs (aRGs), Lzts1 expression is variable, depending on Hes1 expression levels. According to its differential levels, Lzts1 induces diverse RG behaviors: planar division, oblique divisions of aRGs that generate oRGs, and their mitotic somal translocation. Loss-of-function of lzts1 impairs all these cell departure processes. Thus, Lzts1 functions as a master modulator of cellular dynamics, contributing to increasing complexity of the cerebral architecture during evolution.


Sujet(s)
Cerveau/croissance et développement , Cerveau/métabolisme , Cellules épendymogliales/métabolisme , Neurogenèse , Neurones/métabolisme , Protéines suppresseurs de tumeurs/métabolisme , Animaux , Mouvement cellulaire , Cerveau/cytologie , Cellules épendymogliales/cytologie , Souris , Souris transgéniques , Neurones/cytologie , Facteur de transcription HES-1/génétique , Facteur de transcription HES-1/métabolisme , Protéines suppresseurs de tumeurs/génétique
14.
Transplant Proc ; 51(3): 774-778, 2019 Apr.
Article de Anglais | MEDLINE | ID: mdl-30979463

RÉSUMÉ

BACKGROUND: Brachytherapy is one of the standard treatments for localized prostate cancer (CaP). However, the feasibility of brachytherapy for renal transplant recipients (RTRs) is still uncertain. MATERIALS AND METHODS: Between August 2007 and March 2018, all patients who had undergone low-dose-rate (LDR) brachytherapy or high-dose-rate (HDR) brachytherapy for clinically localized CaP at our institution were retrospectively identified (n = 394). Of these patients, 3 had a history of renal transplantation. We reviewed all available clinical data retrospectively. RESULTS: All of the RTRs received ABO-incompatible renal grafts from their spouses and had stable renal graft function before the diagnosis of CaP. The median age at diagnosis of CaP was 65 years (range, 60-67 years). The median time between transplantation and brachytherapy was 7 years (range, 4-10 years). In all of the patients, clinical stage was cT1cN0M0. Two patients received 125I LDR-brachytherapy (dose, 145 Gy) and 1 patient was treated by 192Ir HDR brachytherapy (dose, 19 Gy in 2 fractions) combined with external beam radiation therapy of 39 Gy in 13 fractions. The median follow-up period after brachytherapy was 44 months (range, 34-50 months). During the follow-up period, none of the patients developed disease progression including biochemical recurrence or clinically significant adverse events associated with radiation therapy. CONCLUSIONS: LDR brachytherapy and HDR brachytherapy are safe and technically feasible in RTRs with CaP, and oncological outcomes in RTRs do not appear to be inferior to those of patients who did not receive renal transplant.


Sujet(s)
Curiethérapie/méthodes , Transplantation rénale , Tumeurs de la prostate/radiothérapie , Système ABO de groupes sanguins , Sujet âgé , Histocompatibilité , Humains , Mâle , Adulte d'âge moyen , Tumeurs de la prostate/complications , Dosimétrie en radiothérapie , Études rétrospectives , Receveurs de transplantation , Résultat thérapeutique
16.
Pharmazie ; 74(12): 760-762, 2019 12 01.
Article de Anglais | MEDLINE | ID: mdl-31907119

RÉSUMÉ

Cardiovascular surgery is a highly invasive intervention that is often performed in elderly patients at risks of complications because of malnutrition and reduced immunity. This study investigated nutritional factors that affected length of hospital stay in patients undergoing cardiovascular surgery. Among 68 patients who underwent surgery at the Department of Cardiovascular Surgery of Gifu Municipal Hospital between April 2013 and March 2015, 55 with complete data were included in the analysis. Data on serum albumin (ALB), transferrin (Tf), pre-albumin (PA) and retinol binding protein (RBP) levels were collected. The median length of hospital stay was 29 days (stays of ≥30 days were considered long-term hospitalization). Multivariate analysis (multiple logistic regression) included age (≥ 65 years), sex (female), and ALB (≤ 3.0 g/dL), Tf (≤ 150.0 mg/dL), PA (≤ 10.0 mg/dL) and RBP (≤ 1.5 mg/dL) levels. ALB [odds ratio (OR) 10.37, 95% CI (confidence interval): 1.185-90.80, P = 0.035] and Tf [OR 4.743, 95% CI: 1.375-16.36, P = 0.014] were significantly associated with length of hospital stay. Nutritional management of patients and careful monitoring of ALB and Tf levels can shorten length of hospital stay in patients undergoing cardiovascular surgery.


Sujet(s)
Procédures de chirurgie cardiovasculaire , Hospitalisation , Durée du séjour , État nutritionnel , Sujet âgé , Sujet âgé de 80 ans ou plus , Femelle , Humains , Mâle , Adulte d'âge moyen , Évaluation de l'état nutritionnel , Sérumalbumine/analyse , Transferrine/analyse
17.
J Microsc ; 273(1): 46-52, 2019 Jan.
Article de Anglais | MEDLINE | ID: mdl-30252129

RÉSUMÉ

Organic materials, including carbon, exist inside the transmission electron microscope (TEM) chamber and are adsorbed onto samples under observation during TEM. When these adsorbed organic materials are irradiated by an electron beam, the adsorbed gas is decomposed. Carbon atoms remain on the sample and bond with each other forming a material with an amorphous structure. Due to the carbon deposition on the observation area of the sample, it is contaminated and the TEM image quality is decreased. Ar was introduced into environmental TEM (ETEM) to purge organic material from the sample chamber to reduce contamination growth. After Ar gas was introduced, the contamination was gradually removed. The contamination removal rate was dependent on the Ar pressure. Moreover, it was clear that Ar was ionised by electron beam irradiation and the Ar ions were produced in the ETEM during electron beam irradiation. It is proposed that the Ar ions removed the carbon contamination. LAY DESCRIPTION: Organic materials, including carbon, exist inside the transmission electron microscope (TEM) chamber and are adsorbed onto samples under observation during TEM. When these adsorbed organic materials are irradiated by an electron beam, the adsorbed gas is decomposed. Carbon atoms remain on the sample and bond with each other forming a material with an amorphous structure. Due to the carbon deposition on the observation area of the sample, it is contaminated and the TEM image quality is decreased. Ar was introduced into environmental TEM (ETEM) to purge organic material from the sample chamber to reduce contamination growth. After Ar gas was introduced, the contamination was gradually removed. The contamination removal rate was dependent on the Ar pressure. Moreover, it was clear that Ar was ionised by electron beam irradiation and the Ar ions were produced in the ETEM during electron beam irradiation. It is proposed that the Ar ions removed the carbon contamination.

18.
Annu Int Conf IEEE Eng Med Biol Soc ; 2018: 5741-5744, 2018 Jul.
Article de Anglais | MEDLINE | ID: mdl-30441640

RÉSUMÉ

Currently, microbes are utilized in many fields, such as medicine, food and environment etc. For more application of microbes, we need a new culture system, which can culture target microbes in large quantities at low cost. Thereupon, we propose a culture system using cellulose tubes. Target microbes are encapsulated inside the cellulose tubes, where they acquire nutrients and oxygen through nano pores of the tubes and are protected from competitive microbes even in open environment. To further increase the amount of oxygen and nutritions available for the target microbes, we propose photocatalyst-coated glass balls (PCGB) to sterilize competing microbes outside the tubes. We experimentally verified the effectiveness of the proposed culture system by culturing Coryne gultamicum as the target microbes.


Sujet(s)
Techniques bactériologiques/instrumentation , Cellulose , Verre , Corynebacterium/croissance et développement , Milieux de culture , Oxygène
20.
J Dent Res ; 97(12): 1355-1364, 2018 11.
Article de Anglais | MEDLINE | ID: mdl-29863959

RÉSUMÉ

Tooth enamel is manufactured by the inner enamel epithelium of the multilayered enamel organ. Msx2 loss-of-function mutation in a mouse model causes an abnormal accumulation of epithelial cells in the enamel organ, but the underlying mechanism by which Msx2 regulates amelogenesis is poorly understood. We therefore performed detailed histological and molecular analyses of Msx2 null mice. Msx2 null ameloblasts and stratum intermedium (SI) cells differentiated normally in the early stages of amelogenesis. However, during subsequent developmental stages, the outer enamel epithelium (OEE) became highly proliferative and transformed into a keratinized stratified squamous epithelium that ectopically expressed stratified squamous epithelium markers, including Heat shock protein 25, Loricrin, and Keratin 10. Moreover, expression of hair follicle-specific keratin genes such as Keratin 26 and Keratin 73 was upregulated in the enamel organ of Msx2 mutants. With the accumulation of keratin in the stellate reticulum (SR) region and subsequent odontogenic cyst formation, SI cells gradually lost the ability to differentiate, and the expression of Sox2 and Notch1 was downregulated, leading to ameloblast depolarization. As a consequence, the organization of the Msx2 mutant enamel organ became disturbed and enamel failed to form in the normal location. Instead, there was ectopic mineralization that likely occurred within the SR. In summary, we show that during amelogenesis, Msx2 executes a bipartite function, repressing the transformation of OEE into a keratinized stratified squamous epithelium while simultaneously promoting the development of a properly differentiated enamel organ competent for enamel formation.


Sujet(s)
Organe de l'émail/métabolisme , Épithélium/métabolisme , Protéines à homéodomaine/métabolisme , Améloblastes/métabolisme , Animaux , Différenciation cellulaire , Prolifération cellulaire , Kystes/embryologie , Kystes/métabolisme , Microanalyse par sonde électronique , Organe de l'émail/embryologie , Épithélium/embryologie , Génotype , Hybridation in situ , Méthode TUNEL , Souris , Souris knockout , Microscopie électronique à transmission , RT-PCR , Microtomographie aux rayons X
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