Investigating the etiology of non-carious cervical lesions: Novel µCT analysis

OBJECTIVES

The etiology of non-carious cervical lesions (NCCLs) is not fully understood, limiting treatment and prevention. Our aim was to evaluate the effect of mechanical loading and acid exposure on the cervical tooth region using a random spectrum loading model that simulates the nature of oral mastication.

METHODS

Thirty extracted human premolars were divided into three experimental groups: 1) unloaded teeth immersed in acid (erosion group: Er), 2) loaded teeth immersed in acid (erosion with spectrum loading group: Er-SL), and 3) loaded teeth immersed in distilled water (spectrum loading group: SL). Random spectrum loading with loads ranging from 100 to 500 N was performed. All teeth were scanned using micro-CT. A novel 3D analysis was developed to evaluate the circumferential cervical tissue loss and regions under tension and compression. For parametric and non-parametric comparisons, one-way ANOVA with Tukey post-hoc tests and Kruskal-Wallis with Bonferroni post-hoc tests were used.

RESULTS

A significant difference was observed in the circumferential volumetric loss, with the Er-SL exhibiting the greatest volume loss (p < 0.001). Moreover, in the loaded groups (Er-SL and SL), regions subjected to tension showed significantly greater loss (p < 0.001, p = 0.007) compared with regions subjected to compression.

CONCLUSIONS

The novel high-resolution micro-CT analysis provided new insights into the etiology of NCCLs. The results suggested that the cumulative effect of mechanical loading and acid exposure may play a major role in NCCL formation.

CLINICAL SIGNIFICANCE

This study investigates the etiology of NCCLs by examining the combined effects of occlusal loads and acid exposure on cervical tissue loss. Understanding the pathogenesis of NCCLs paves the way for the development of improved preventative measures and treatment strategies to prevent tooth structure degradation.

Cis-regulatory architecture and functions of a gene desert controlling pleiotropic expression and cardiac pacemaker development

 

Gene deserts are extensive genomic regions spanning more than 500 kilobases and enriched near developmental genes. Despite their proposed critical roles in development, the enhancer architecture, and biological functions of most gene deserts in mammalian genomes remain unknown. The Shox2 transcription factor is a key regulator of cardiac pacemaker differentiation and at the genomic level is flanked by a centromeric gene desert harboring a multitude of predicted cis-regulatory modules (CRMs). Using CRISPR-Cas9 we demonstrate a requirement of this gene desert for pleiotropic expression and embryonic survival through full control of Shox2 in the sinoatrial node (SAN). To decode the underlying chromatin architecture and CRM logic, we performed region-specific chromatin conformation capture, epigenomic analysis and transgenic in vivo reporter assays. While the Shox2 regulatory landscape was found partitioned into largely tissue-invariant chromatin loops, we identified a surprising cardiac-specific contact domain within the gene desert. Subsequent transgenic analysis revealed clustering of non-cardiac enhancers with activities in limb, craniofacial or neuronal populations in this domain, pointing to a potential tissue-specific 3D-mechanism for enhancer attenuation. In addition, SAN-chromatin assessment and H3K27ac profiling from human fetal cardiac compartments enabled the identification of a unique cardiac enhancer located outside of the contact domain and essential for robust Shox2 levels during cardiac pacemaker development. In summary, our results serve as a blueprint to investigate gene desert function in context to cardiac defects and identify the Shox2 gene desert as a robust cis-regulatory hub indispensable for pleiotropic patterning, cardiac pacemaker differentiation and embryonic survival.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation (SNSF),National Institutes of Health (NIH)

An SSP-PCR method for the rapid detection of disease-associated alleles HLA-A*29 and HLA-B*51

HLA-A*29 and HLA-B*51 are associated with birdshot uveitis and Behçet's disease, respectively, and are used as a diagnostic criterion in patients with suspected disease, requiring their detection in diagnostic laboratories. While commercial tests for individual HLA alleles are available for other disease-associated HLA variants, no similar allele-specific assays are available for HLA-A*29 and HLA-B*51. Here, we report sequence-specific priming-polymerase chain reaction (SSP-PCR) methods for the detection of HLA-A*29 and HLA-B*51 using a single PCR reaction per allele. The assays were tested in 30 and 32 previously HLA-typed samples, respectively, representing >97% of HLA-A alleles and >93% of HLA-B alleles in a European population. A concordance of 100% was observed with previous typing results, validating these methods for use in a diagnostic or research context.