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Objective: To analyse the pan-genome of three black-pigmented periodontal pathogens: Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens., Methods: Pan-genome analyses of 66, 33 and 5 publicly available whole-genome sequences of P. gingivalis, P. intermedia and P. nigrescens, respectively, were performed using Pan-genome Analysis Pipeline software (version 1.2.1; Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, PR China). Phylogenetic trees were constructed based on the entire pan-genome and single nucleotide polymorphisms within the core genome. The distribution and abundance of virulence genes in the core and dispensable genomes were also compared in the three species., Results: All three species possess an open pan-genome. The core genome of P. gingivalis, P. intermedia and P. nigrescens included 1001, 1514 and 1745 orthologous groups, respectively, which were mainly related to basic cellular functions such as metabolism. The dispensable genome of P. gingivalis, P. intermedia and P. nigrescens was composed of 2814, 2689 and 906 orthologous groups, respectively, and it was enriched in genes involved in pathogenicity or with unknown functions. Phylogenetic trees presented a clear separation of P. gingivalis, P. intermedia and P. nigrescens, verifying the reclassification of the black-pigmented species. Furthermore, the three species shared almost the same virulence factors involved in adhesion, proteolysis and evasion of host defences. Some of these virulence genes were conserved across species whereas others belonged to the dispensable genome, which might be acquired through horizontal gene transfer., Conclusion: This study highlighted the usefulness of pan-genome analysis to infer evolutionary cues for black-pigmented species, indicating their homology and phylogenomic diversity.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ), as one serious side-effect of bisphosphonate therapy, has been known for more than ten years since it was first reported in 2003. In the majority of the cases, BRONJ occurs more commonly in the mandible. Those involving the maxilla are relatively few. This paper reported a case that a patient with multiple myeloma developed bilateral maxillary BRONJ after tooth extraction. The patient had used bisphosphonates for more than three years, meanwhile with uncontrolled diabetes mellitus. The patient recovered completely after surgical treatment, in combination with diabetes disease control and antibiotics application. Two key factors to ensure the success of surgical treatment are as follows: sufficient removal of infected and necrotic tissue, and good blood-supply for the local flap to help completely close the wound. The literature was reviewed to analyze the reasons why bone necrosis related to bisphosphonates was most likely to occur in the jaw, especially in the mandible, according to the pathogenesis of this disease. Furthermore, the related risk factors of BRONJ presented in this case were discussed, such as tooth extraction, oral infection and diabetes mellitus, etc. We summarized adjuvant prophylaxes for prevention of BRONJ after tooth extraction, for example, drug holiday that could be used in the dental clinic. This case report reminds us that it's of great importance to establish the awareness that the osteonecrosis of the jaw may be related to the use of some bone-stabilizers. As for patients with a history of exposure to antiresorptive or antiangiogenic agents, dentists are supposed to be cautious. It's recommended to take appropriate measures in perioperative period of oral surgical treatment to prevent BRONJ.

The ZM-1 tissue microarrayer designed by our groups is manufactured in stainless steel and brass and contains many features that make TMA (tissue microarray) paraffin blocks construction faster and more convenient. By means of ZM-1 tissue microarrayer, biopsy needles are used to punch the donor tissue specimens respectively. All the needles with the punched specimen cylinders are arrayed into the array-board, with an array of small holes dug to fit the needles. All the specimen cylinders arraying and the TMA paraffin block shaping are finished in only one step so that the specimen cylinders and the paraffin of the TMA block can very easily be incorporated and the recipient paraffin blocks need not be made in advance, and the paraffin used is the same as that for conventional pathology purpose. ZM-1 tissue microarrayer is easy to be manufactured, does not need any precision location system, and so is much cheaper than the currently used instrument. Our method's relatively cheap and simple ZM-1 tissue microarrayer technique of constructing TMA paraffin block may facilitate popularization of the TMA technology.

ZM-1 tissue microarrayer designed by our group is manufactured in stainless steel and brass. It features an easier and faster preparation for tissue microarrays. By means of it, a group of biopsy needles are used to punch the donor tissue specimens respectively, and all the needles with the punched specimen cylinders are arranged into the array-board, where small holes have been digged to fit the needles. All the specimen cylinders arraying and the tissue microarray block's shaping are finished simultaneously. ZM-1 tissue microarrayer with a lower cost of manufacture, is capable of preparing the tissue microarrays conveniently, efficiently and quality-controllably.