Epidemiology of healthcare-associated infections and outcomes among open and robotic pancreatoduodenectomy: A retrospective study from 2013 to 2022.

BACKGROUND AND AIM: Healthcare-associated infections (HAIs) after pancreaticoduodenectomy (PD) are one of the common postoperative complications. This study aims to investigate the epidemiology of postoperative HAIs in patients with open pancreaticoduodenectomy (OPD) and robotic pancreaticoduodenectomy (RPD). METHODS: This retrospective cohort study described the trend of HAIs in patients undergoing PD from January 2013 to December 2022 at a tertiary hospital. Patients were divided into OPD and RPD, and the HAIs and outcomes were compared. RESULTS: Among 2632 patients who underwent PD, 230 (8.7%, 95% confidence interval [CI] 7.7-9.9%) were diagnosed with HAIs, with a decreasing trend from 2013 to 2022 (P < 0.001 for trend). The incidence of postoperative HAIs was significantly higher in patients with OPD than RPD (9.6% vs 5.8%; P = 0.003). The incidence of HAIs for patients with OPD showed a decreasing trend (P = 0.001 for trend), and the trend for RPD was not significant (P = 0.554 for trend). Logistic regression showed that RPD was significantly associated with postoperative HAIs after adjusting for covariates (adjusted odds ratio = 0.654; 95% CI 0.443-0.965; P = 0.032), especially in the subgroup of patients without preoperative biliary drainage (adjusted odds ratio = 0.486; 95% CI 0.292-0.809; P = 0.006). Regarding clinical outcomes, RPD has a shorter length of stay and a more expensive charge than OPD (all P < 0.05). CONCLUSION: Postoperative HAIs in patients with PD showed a decreasing trend in recent years, especially in OPD. RPD was significantly associated with reduced postoperative HAIs and length of stay, although the charge is more expensive. Attention should be paid to postoperative HAIs in OPD, and it is imperative to continue reducing the costs of RPD.

Which Bone Marrow Sparing Strategy and Radiotherapy Technology Is Most Beneficial in Bone Marrow-Sparing Intensity Modulated Radiation Therapy for Patients With Cervical Cancer?

BACKGROUND: To evaluate the dosimetric parameters of different bone marrow sparing strategies and radiotherapy technologies and determine the optimal strategy to reduce hematologic toxicity associated with concurrent chemoradiation (cCRT) for cervical cancer. METHODS: A total of 15 patients with Federation International of Gynecology and Obsterics (FIGO) Stage IIB cervical cancer treated with cCRT were re-planned for bone marrow (BM)-sparing plans. First, we determined the optimal BM sparing strategy for intensity modulated radiotherapy (IMRT), including a BMS-IMRT plan that used total BM sparing (IMRT-BM) as the dose-volume constraint, and another plan used os coxae (OC) and lumbosacral spine (LS) sparing (IMRT-LS+OC) to compare the plan without BM-sparing (IMRT-N). Then, we determined the optimal technology for the BMS-IMRT, including fixed-field IMRT (FF-IMRT), volumetric-modulated arc therapy (VMAT), and helical tomotherapy (HT). The conformity and homogeneity of PTV, exposure volume of OARs, and efficiency of radiation delivery were analyzed. RESULTS: Compared with the IMRT-N group, the average volume of BM that received ≥10, ≥20, ≥30, and ≥40 Gy decreased significantly in both two BM-sparing groups, especially in the IMRT-LS+OC group, meanwhile, two BMS-IMRT plans exhibited the similar effect on PTV coverage and other organs at risk (OARs) sparing. Among three common IMRT techniques in clinic, HT was significantly less effective than VMAT and FF-IMRT in the aspect of BM-Sparing. Additionally, VMAT exhibited more efficient radiation delivery. CONCLUSION: We recommend the use of VMAT with OC and LS as separate dose-volume constraints in cervical cancer patients aiming at reducing hematologic toxicity associated with cCRT, especially in developing countries.

[Advances in the RNA-directed DNA methylation in plants].

The RNA-directed DNA Methylation (RdDM) is one type of epigenetic modification which was firstly discovered in plant. RdDM can directly cause DNA modifications of the genome through RNA-DNA interactions. In plant, both of RdDM and mRNA degradation induced by siRNA can silence sequence specific genes through RNA. They play very significant roles in chromosome rearrangement, defence of virus invasion, regulation of gene expression and many processes of plant development. However, the mechanisms of RdDM are still unclear. In this paper the basic characteristics of RdDM were briefly summarized and advances in studies on mechanisms of RdDM were reviewed. These include the kinds of DNA methyltransferases and their functional mechanisms in RdDM, the relationships between DNA methylation and chromatin modification, and important proteins involved in the RdDM process. In plants, RdDM may occur at both the transcriptional and post-transcriptionnal levels, both of which induce gene silencing. Methylation of the target gene promoter correlates with transcriptional gene silencing (TGS) whereas methylation of the coding sequence is associated with post-transcriptional gene silencing (PTGS). RdDM and RNAi all depend on the similar siRNA and enzymes, such as DCL3, RdR2, SDE4 and AGO4. There are at least three kinds of DNA methyltransferases, DRM1/2, MET1 and CMT3, in pants. They can interact with and modifies all cytidines within the DNA regions homologous to RNA sequence. Furthermore, methylation of lysine 9 in Histone H3 can affect the methylation of cytidines.

[The study of optimal conditions of electroporation in Pseudomonas aeruginosa].

A P. aeruginosa strain PA68 isolated from the sputum of a patient suffering from bronchiectasis was used as the recipient strain. Optimum conditions including growth stage of the strain, electroshock voltage, concentration and preservation of competent cell were defined for the electroporation of PA68 with plasmid pSMC28. It was showed that the highest transformation efficiency was up to 1.68 x 10(3) CFU/microgram DNA under the optimum conditions in which the competent cells were collected at logarithmic growth phase (OD(540) = 0.7-0.8) and concentrated to about 10(11) cells/ml, the mixture of the competent cells and plasmid pSMC28 was eletroporated at 2.6 kV. With this optimal condition, Mu transponson complexes have been successfully transformed into P. aeruginosa strain PA68 and the obtained efficiency was 2.47 x 10(4) CFU/microgram DNA. This is the first time to electroporate Mu transposon complexes into Pseudomonas spp. The artificial Mu transposons could integrate into bacterial genomes at a single site randomly. Then the phenotype change was the result of the gene inactivation caused by Mu transposon insertion. That will be very helpful for the study of genomic function of Pseudomonas spp.

[The action of S1 nuclease and a cloning strategy for microcircular DNAs].

S1 nuclease (from Aspergillus oryzae) is a specific enzyme to degrade single stranded DNA or RNA molecules. It has been reported to be able to convert superhelical circular DNA molecules into open circle or linear forms under certain conditions, but this function has not been well explored. In order to use the action of S1 nuclease to linearize circular DNA and develop a novel way of cloning microcircular DNAs, the pUC19 was used to investigate the relationship between the linearization efficiency of S1 nuclease and the amount of enzyme used. By this way the optimal conditions for linearization of circular DNAs by S1 nuclease would be determined. 0.3u to 17u S1 nuclease per 100ng pUC19 DNA was added into a 25 microL system, respectively, to perform the reaction. The effectiveness of enzyme digestion was realized by electrophoresis in a 1.2% agarose gel. The results showed that along with the increase in enzyme amount from 0.3u to 17u a gradual decrease in the superhelical form, a gradual increase in the linear form and then in the circular form was obvious. The conversion from superhelical form to linear and circular form was directly related to the enzyme amount used. A higher proportion of linear DNA molecules was achieved by using 5 to 17u S1 nuclease per 100ng DNA. Besides, electrophoretic mobility of the S1 nuclease-linearized pUC19 was the same as that of the linear form produced by restriction enzyme digestion. According to the result of phiX174 digested by S1 nuclease it has been proposed that the enzyme cleaves first randomly on one site of one strand, thus converting the superhelical molecules into open circle form, and then on the same site of the complementary strand to produce the linear form. Therefore, the S1 nuclease-linearized DNA molecules are intact in the sense of their length and can be used for cloning. The plasmid-like DNA pC3 from cucumber mitochondria is a double stranded circular DNA molecule with about 550bp and the smallest known plasmid-like DNA in eukaryotic mitochondria. Many attempts have been made to linearize the molecule by using restriction enzymes but failed. Therefore, S1 nuclease was used to linearize pC3 based on the results obtained with pUC19. The linearized pC3 DNA molecules formed a very sharp band in a 2.5% agarose gel after electrophoresis. They were then recovered from the gel, added an "A" tail and ligated with T-vector. After transformation into E. coli JM109 cells, the positive clones were, screened by the blue-white selection. The insert was then cut using restriction enzymes EcoRI and Pst I. The result of electrophoresis shows that the electrophoretic mobility of the insert is just the same as that predicted. A 32 P-labled probe was synthesized using pC3 as the template and Southern blot analysis was carried out. The result shows that the inserted DNA is hybridized to the probe, which indicates that the cloned DNA fragment is from pC3. The sequence information of the insert shows that the plasmid-like DNA pC3 was 537bp in length. The nucleotide sequence was deposited in the GenBank (the accession number is AF522195).