Transcriptional Regulation of Jaw Osteoblasts: Development to Pathology.

Craniofacial and jaw bones have unique physiological specificities when compared to axial and appendicular bones. However, the molecular profile of the jaw osteoblast (OB) remains incomplete. The present study aimed to decipher the bone site-specific profiles of transcription factors (TFs) expressed in OBs in vivo. Using RNA sequencing analysis, we mapped the transcriptome of confirmed OBs from 2 different skeletal sites: mandible (Md) and tibia (Tb). The OB transcriptome contains 709 TF genes: 608 are similarly expressed in Md-OB and Tb-OB, referred to as "OB-core"; 54 TF genes are upregulated in Md-OB, referred to as "Md-set"; and 18 TF genes are upregulated in Tb-OB, referred to as "Tb-set." Notably, the expression of 29 additional TF genes depends on their RNA transcript variants. TF genes with no previously known role in OBs and bone were identified. Bioinformatics analysis combined with review of genetic disease databases and a comprehensive literature search showed a significant contribution of anatomical origin to the OB signatures. Md-set and Tb-set are enriched with site-specific TF genes associated with development and morphogenesis (neural crest vs. mesoderm), and this developmental imprint persists during growth and homeostasis. Jaw and tibia site-specific OB signatures are associated with craniofacial and appendicular skeletal disorders as well as neurocristopathies, dental disorders, and digit malformations. The present study demonstrates the feasibility of a new method to isolate pure OB populations and map their gene expression signature in the context of OB physiological environment, avoiding in vitro culture and its associated biases. Our results provide insights into the site-specific developmental pathways governing OBs and identify new major OB regulators of bone physiology. We also established the importance of the OB transcriptome as a prognostic tool for human rare bone diseases to explore the hidden pathophysiology of craniofacial malformations, among the most prevalent congenital defects in humans.

Oral Condition and Incident Coronary Heart Disease: A Clustering Analysis.

Poor oral health has been linked to coronary heart disease (CHD). Clustering clinical oral conditions routinely recorded in adults may identify their CHD risk profile. Participants from the Paris Prospective Study 3 received, between 2008 and 2012, a baseline routine full-mouth clinical examination and an extensive physical examination and were thereafter followed up every 2 y until September 2020. Three axes defined oral health conditions: 1) healthy, missing, filled, and decayed teeth; 2) masticatory capacity denoted by functional masticatory units; and 3) gingival inflammation and dental plaque. Hierarchical cluster analysis was performed with multivariate Cox proportional hazards regression models and adjusted for age, sex, smoking, body mass index, education, deprivation (EPICES score; Evaluation of Deprivation and Inequalities in Health Examination Centres), hypertension, type 2 diabetes, LDL and HDL serum cholesterol (low- and high-density lipoprotein), triglycerides, lipid-lowering medications, NT-proBNP and IL-6 serum level. A sample of 5,294 participants (age, 50 to 75 y; 37.10% women) were included in the study. Cluster analysis identified 3,688 (69.66%) participants with optimal oral health and preserved masticatory capacity (cluster 1), 1,356 (25.61%) with moderate oral health and moderately impaired masticatory capacity (cluster 2), and 250 (4.72%) with poor oral health and severely impaired masticatory capacity (cluster 3). After a median follow-up of 8.32 y (interquartile range, 8.00 to 10.05), 128 nonfatal incident CHD events occurred. As compared with cluster 1, the risk of CHD progressively increased from cluster 2 (hazard ratio, 1.45; 95% CI, 0.98 to 2.15) to cluster 3 (hazard ratio, 2.47; 95% CI, 1.34 to 4.57; P < 0.05 for trend). To conclude, middle-aged individuals with poor oral health and severely impaired masticatory capacity have more than twice the risk of incident CHD than those with optimal oral health and preserved masticatory capacity (ClinicalTrials.gov NCT00741728).

On the biocompatibility of a novel Ti-based amorphous composite: structural characterization and in-vitro osteoblasts response.

Titanium and its alloys are frequently used as dental and orthopaedic implants due to their high mechanical strength, low elastic modulus and biocompatibility. However, as these materials have a poor wear resistance, tribo-chemical reactions during use produce debris accumulation, resulting in adverse cellular responses. In that sense, amorphous based materials are potential candidates, considering their hardness and crack growth resistance. This paper reports on the structural characterization of the as-quenched Ti45Zr38Ni17 alloy. This system displays a duplex structure never mentioned before with a low dispersion of nanometric beta-phase particles in an amorphous matrix. Moreover, in order to explore the biocompatibility of such composite, primary osteoblasts cultures are used to analyse cell behaviour around and upon the metallic surface. Osteoblasts attach and proliferate on the material as demonstrated by scanning electron microscopy. Cell proliferation and bone nodule formation are also observed in cultures with Ti45Zr38Ni17 particles by phase contrast microscope. In addition, transmission electron microscopy reveals ultrastructural features very close to those observed in vivo during intramembranous ossification with active osteoblasts surrounded by an extracellular matrix and a mineralized one. In conclusion, these results demonstrate that osteoblasts, cultured in presence of Ti45Zr38Ni17 alloy, proliferate, differentiate and synthesize bone matrix.

Lysozyme activity in animal extracts after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

1. Lysozyme activity was detected after electrophoresis in sodium dodecyl sulfate-polyacrylamide gels containing 0.2% (W/V) autoclaved Micrococcus lysodeikticus cells as substrate. 2. Lysozyme activity appeared as clear lysis zones after incubation of opaque gels at 37 degrees C in buffered Triton X-100. 3. As low as 0.1 pg of purified hen egg white lysozyme could be detected after 16 hr incubation at pH 6.5. 4. Bands with lytic activity from kidney and pancreas acetone powders, bird's egg whites and vitelline membranes, animal sera and human saliva corresponded to c-type (Mr 14,500), g-type (Mr 20,500) or both lysozymes as far as molecular weight is concerned. 5. Some extracts, like porcine kidney, exhibited more than two bands. 6. Bands with lytic activity migrating at the level of g-type lysozymes were detected in some kidney and pancreas extracts.

Some thaumatin-like proteins hydrolyse polymeric beta-1,3-glucans.

Thaumatin and 12 purified thaumatin-like (TL) proteins were surveyed for their capacity to hydrolyse beta-1,3-glucans by using an in-gel glucanase assay. Six TL proteins identified by N-terminal amino acid microsequencing were found to be active on carboxymethyl(CM)-pachyman: a barley leaf stress-related permatin, two tomato fruit osmotins, a cherry fruit and two tobacco stigma proteins. TL enzymes ranged in specific activity from 0.07 to 89 nkat mg-1 with CM-pachyman as substrate. Hydrolytic activities were not restricted to TL proteins strongly binding to water-insoluble beta-1,3-glucans since the two osmotins were active without tight binding to pachyman. Some TL proteins hydrolysed crude fungal walls and one barley TL enzyme even lysed fungal spores. No activity was observed on laminarin in the in-gel hydrolase assay. Thin-layer chromatography revealed that the six enzymes acted as endo-beta-1, 3-glucanases leading to the formation of various oligoglucosides. Thus far, the TL enzymes (EC 3.2.1.x) appeared different from the well-known beta-1,3-glucanases (EC 3.2.1.39). No activity was found with thaumatin, zeamatin, tobacco leaf PR-R protein and four stress-related TL proteins from barley and pea. This is the first demonstration that diverse TL proteins are enzymatically active. The functions of some TL proteins must be reassessed because they display endo-beta-1,3-glucanase activity on polymeric beta-1, 3-glucans.