The role of vitamin D receptor in predentin mineralization and dental repair after injury.

Dentin is a permeable and complex tubular composite formed by the mineralization of predentin that mineralization and repair are of considerable clinical interest during dentin homeostasis. The role of Vdr, a receptor of vitamin D, in dentin homeostasis remains unexplored. The aim of the present study was to assess the impact of Vdr on predentin mineralization and dental repair. Vdr-knockout (Vdr-/-) mice models were constructed; histology and immunohistochemistry analyses were conducted for both WT and Vdr-/- mice. The finding revealed a thicker predentin in Vdr-/- mice, characterized by higher expression of biglycan and decorin. A dental injury model was employed to observe tertiary dentin formation in Vdr-/- mice with dental injuries. Results showed that tertiary dentin was harder to form in Vdr-/- mice with dental injury. Over time, heightened pulp invasion was observed at the injury site in Vdr-/- mice. Expression of biglycan and decorin was reduced in the predentin at the injury site in the Vdr-/- mice by immunohistochemistry. Taken together, our results imply that Vdr plays a regulatory role in predentin mineralization and tertiary dentin formation during dentin homeostasis.

Molecular characteristic analysis for the VP1 region of coxsackievirus A6 strains isolated in Jiujiang area, China, from 2012 to 2013.

BACKGROUND: Enterovirus 71 (EV-A71) and Coxsackievirus A16 (CV-A16) are the most common causative agents causing hand, foot, and mouth disease (HFMD). However, coxsackievirus A6 (CV-A6), previously largely ignored, became the predominant pathogen in China in 2012. The objective of this study is to investigate the genetic characteristics and molecular epidemiology of HFMD caused by CV-A6 to guide the diagnosis and treatment of the disease, as well as disease prevention. MATERIAL AND METHODS: A total of 138 suspected HFMD cases were enrolled in this study and analyses based on complete VP1 nucleotide sequences were performed to determine the evolutionary trajectory of emerging CV-A6. RESULTS: Among 138 samples in Jiujiang, 125 (90.58%) were positive for enterovirus, the most frequently presented serotypes were CV-A6 (77, 61.60%), CV-A16 (28, 22.40%), EV-A71 (6, 4.80%) and untyped enteroviruses (14, 11.20%). Seventy-seven CV-A6 positive specimens were analyzed for the complete VP1 sequences by sequencing and 36 representative isolates were selected to perform nucleotide sequence similarity analysis. The results showed that 36 strains isolated from HFMD patients were clustered closely to the mainland China and were far from prototype strain CV-A6/Gdula (AY421764) and other international subtypes. Moreover, phylogenetic analysis of the VP1 gene revealed that 36 circulating strains were not significantly concentrated in one branch, but were widely distributed in each branch. CONCLUSIONS: Continuous surveillance of HFMD etiological agents other than EV-A71 and CV-A16 is necessary. CV-A6 is emerging as the most common pathogen causing HFMD. Closely monitoring the magnitude and trend of CV-A6 epidemic and the trend of pathogenic spectrum changes can provide scientific basis for this disease prevention and control to the department of disease control.