Publications by authors named "Rongxin Shi"

A-234 (ethyl -[1-(diethylamino)ethylidene]phosphoramidofluoridate) is one of the highly toxic Novichok nerve agents, and its efficient degradation is of significant importance. The possible degradation mechanisms of A-234 by HO, HO, NH, and their combinations have been extensively investigated by using density functional theory (DFT) calculations. According to the initial intermolecular interaction and the proton transfer patterns between the detergent and the substrate A-234, the A-234 degradation reaction is classified into three categories, denoted as A, B, and C.

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Article Synopsis
  • Undifferentiated pleomorphic sarcoma (UPS) in the oral-maxillary area is uncommon but can progress rapidly to a dangerous stage due to complex anatomical structures.
  • The diagnosis relies on histology and immunohistochemistry after ruling out other conditions, and treatments typically follow protocols for oral squamous cell carcinoma.
  • The study found a median overall survival of 7.75 months, with some cases showing longer survival following neoadjuvant chemotherapy and identified GBP4 as a potential driver gene along with a mutation in PIK3CA, highlighting new therapeutic avenues.
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DNA glycosylases remove aberrant DNA nucleobases as the first enzymatic step of the base excision repair (BER) pathway. The alkyl-DNA glycosylases AlkC and AlkD adopt a unique structure based on α-helical HEAT repeats. Both enzymes identify and excise their substrates without a base-flipping mechanism used by other glycosylases and nucleic acid processing proteins to access nucleobases that are otherwise stacked inside the double-helix.

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DNA glycosylases preserve genome integrity and define the specificity of the base excision repair pathway for discreet, detrimental modifications, and thus, the mechanisms by which glycosylases locate DNA damage are of particular interest. Bacterial AlkC and AlkD are specific for cationic alkylated nucleobases and have a distinctive HEAT-like repeat (HLR) fold. AlkD uses a unique non-base-flipping mechanism that enables excision of bulky lesions more commonly associated with nucleotide excision repair.

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Yatakemycin (YTM) is an extraordinarily toxic DNA alkylating agent with potent antimicrobial and antitumor properties and is the most recent addition to the CC-1065 and duocarmycin family of natural products. Though bulky DNA lesions the size of those produced by YTM are normally removed from the genome by the nucleotide-excision repair (NER) pathway, YTM adducts are also a substrate for the bacterial DNA glycosylases AlkD and YtkR2, unexpectedly implicating base-excision repair (BER) in their elimination. The reason for the extreme toxicity of these lesions and the molecular basis for the way they are eliminated by BER have been unclear.

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Threats to genomic integrity arising from DNA damage are mitigated by DNA glycosylases, which initiate the base excision repair pathway by locating and excising aberrant nucleobases. How these enzymes find small modifications within the genome is a current area of intensive research. A hallmark of these and other DNA repair enzymes is their use of base flipping to sequester modified nucleotides from the DNA helix and into an active site pocket.

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DNA glycosylases are important repair enzymes that eliminate a diverse array of aberrant nucleobases from the genomes of all organisms. Individual bacterial species often contain multiple paralogs of a particular glycosylase, yet the molecular and functional distinctions between these paralogs are not well understood. The recently discovered HEAT-like repeat (HLR) DNA glycosylases are distributed across all domains of life and are distinct in their specificity for cationic alkylpurines and mechanism of damage recognition.

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Purpose: To evaluate the usefulness of rigid internal fixation in management of oral and maxillofacial comminuted fracture.

Methods: From July 2004 to June 2007, 79 patients with oral and maxillofacial comminuted fractures (including 45 males, 34 females, aged from 9 to 69 years, 11 mandibular fractures, 31 ZMC fractures, 37 maxillary fractures) were treated with open reduction and rigid internal fixation.

Results: Facial profile in 79 cases and cross-bite in 77 cases were corrected satisfactorily.

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