Analysis of pathogenic bacteria of severe infection in cancer patients after chemoradiotherapy / 中国中西医结合急救杂志

Objective To investigate the characteristics of pathogenic bacteria in cancer patients with severe infection after radiotherapy and chemotherapy and the application value of metagenomic next-generation sequencing(NGS)in the detection of pathogenic bacteria.Methods A total of 112 patients with severe infection after malignant tumor radiation and chemotherapy admitted to Department of Critical Care Medicine of Wuwei Tumor Hospital from October 2019 to August 2023 were selected as the research objects.A total of 150 specimens from suspected infection sites were collected and tested by traditional etiology and NGS.The characteristics of pathogenic bacteria in severe infection of cancer patients after chemoradiotherapy and the application value of NGS in pathogen detection were analyzed.Results Among 150 samples of 112 patients with severe infection after radiotherapy and chemotherapy,the highest proportion of respiratory system infection was 51.79%(58 cases),followed by 25.89%(29 cases)of bloodstream infection,the lowest central nervous system infection rate was 1.79%(2 cases).Gram-negative bacteria were the most common pathogenic bacteria[NGS 35.33%(53 cases),traditional pathogen detection 23.33%(35 cases)],followed by Gram-positive bacteria[NGS 20.67%(31 cases),traditional pathogen detection 12.00%(18 cases)],and multi-drug resistant bacteria infection rate was more than 80.00%,multi-drug resistant fungal infection rate also reached 28.57%.In the patients with severe infection after radiotherapy and chemotherapy,the positive rate of pathogenic bacteria of NGS was significantly higher than that of traditional pathogen detection[87.33%(131/150)vs.42.67%(64/150),P＜0.01],and the positive detection rate of Gram-negative bacteria,Gram-positive bacteria,fungi and other pathogens was significantly higher than that of traditional pathogen detection[Gram-negative bacteria:35.33%(53/150)vs.23.33%(35/150),Gram-positive bacteria:20.67%(31/150)vs.12.00%(18/150),fungi:22.67%(34/150)vs.6.67%(10/150),others:8.67%(13/150)vs.0.67%(1/150),both P＜0.05].Conclusions The detection rate of pathogenic bacteria of NGS in patients with severe infection after radiotherapy and chemotherapy was significantly higher than that of traditional pathogen detection.The distribution and drug resistance of pathogenic bacteria in severe infection after radiotherapy and chemotherapy are unique,and strengthening the detection of pathogenic bacteria is helpful to improve the curative effect.

Comparison of the diagnostic performances between strain elastography and shear-wave elastography in differentiation of benign and malignant solid breast lesions / 中华医学超声杂志（电子版）

Objective To compare the diagnostic performances of strain elastography (SE) and shear-wave elastography (SWE) in differentiating benign and malignant solid breast lesions. Methods From January 2015 to December 2015, 150 patients with 155 lesions were examined with SE and SWE respectively in the First Affiliated Hospital with Nanjing Medical University. Elasticity scores on a improved 5-point scale,strain ratio (SR), maximum elasticity (Emax), mean elasticity (Emean), standard deviation of the elasticity (Esd) and the lesion-to-fat elasticity ratio (Eratio) were assessed. The receiver operating characteristic (ROC) curve of SE and SWE parameters were plotted to assess the value in distinguishing benign and malignant breast lesions. The results were compared using the area under the ROC curve (AUC). The accuracy of the parameters with the largest AUC were compared between SE and SWE by McNemar test in different breast imaging reporting and data system (BI-RADS) categories. Results The AUC of elasticity scores, SR, Emax,Emean, Esd and Eratio were 0.823, 0.810, 0.877, 0.835, 0.881 and 0.853, respectively. The SE and SWE parameter with the largest AUC were elasticity scores and Esd respectively. The accuracy of Esd was higher than that of elasticity scores(86.3% vs 64.7%)in 4A lesions (2=4.639, P < 0.05). There were no significant differences in accuracy in other BI-RADS categories. Conclusions Both SE and SWE were helpful for the differentiation of benign and malignant solid breast lesions, and the diagnostic performance of SE and SWE was similar. The optimization of elastography can be achieved by combination with BI-RADS.

Identification of key residues in the catalytic center JadH involved in binding substrates or catalysis of jadomycin biosynthesis / 生物工程学报

JadH is a bifunctional hydoxylase/dehydrase involved in jadomycin biosynthesis; it catalyzes a post-PKS modification reaction to convert 2,3-dehydro-UWM6 to dehydrorabelomycin. To identify the key residues involved in substrate-binding and catalysis, structural modeling and multiple sequence alignments of JadH homologs were performed to predict nine residues at the proximity of substrate. Site-directed mutagenesis of the corresponding residues and in vitro evaluation of the activities of the mutant enzymes, indicate these mutations severely reduced JadH activity. Our results indicate these residues are specifically involved in substrate-binding or catalysis in JadH.

Progress in the understanding of the function of atypical response regulators: a review / 生物工程学报

Two component system is a signal transduction system. It typically consists of a sensor histitine kinase and a cognate response regulator (RR) component. The activity of RR is regulated by a phosphorylation dependent mechanism. In recent years, the existence of atypical response regulators (ARRs), which rely on a phosphorylation independent mechanism to regulate their activity, have been recognized. ARRs are involved in the regulation of bacterial growth and development, antibiotic biosynthesis, iron transport, among others. Here we review the recent advances in the understanding of the structure and function of atypical response regulators, by using JadR1, a regulator in jadomycin biosynthesis in Streptomyces, as an example to elucidate the novel mechanism used by ARR to fine-tune its activity.

Structure and function of tonoplast Cation/H+ antiporters in plant: a review / 生物工程学报

Cation transporters play important roles in modulating the concentration of intracellular metal ions. The vacuole is an important storage organelle for many ions. Cation (Ca+)/H+ antiporters (CAXs) located at vacuolar membrane are mainly involved in the Ca2+ flux into the vacuole, and appear to be capable of transporting various divalent cations to some degree. Several CAX genes have been isolated and characterized from various plants in recent years. Four domains of plant CAXs have been identified: NRR regulates Ca2+ transport by a mechanism of N-terminal autoinhibition; Ca domain and C domain confer Ca2+ and Mn2+ specificity among CAX transporters, respectively; D domain plays a part in the regulation of cytosolic pH. AtCAXs identified in Arabidopsis thaliana are involved in the growth, development and stress adaption of plant. AtCAX3 is the mainly Ca2+/H+ transporter in response to salt stress; AtCAX2 and AtCAX4 participate in transportation and detoxicification of heavy metal ions (Cd2+, Zn2+, and Mn2+) in cells under heavy metal stress, and impact root/shoot Cd partitioning in plant. These suggest that CAX genes may be useful for nutritional enhancement of plants, and for increasing phytoremediation potential. Here, the classification, structure and function of CAXs in plants are reviewed.