An Epidemiological Study of Drug Resistance and Resistance Genes in Bovine Escherichia coli Isolates in Heilongjiang Province of China

Background: To explore the epidemiology of bovine multidrug-resistant Escherichia coli isolates and resistance genes in Heilongjiang province of China. This study examined the prevalence of genes in bovine E. coli isolates, which confer resistance to antibiotics that are commonly used in the clinic, in regions of Baiquan, Shangzhi, and Songbei of Harbin. The purpose of the study was to investigate the epidemiology of the main resistance genes of bovine E. coli isolates in clinical veterinary medicine, and to provide a theoretical basis for preventing the spread of drug-resistant bacteria, as well as for rational drug use.Materials, Methods & Results: The sensitivity of 105 isolates to 22 antibiotics was determined using the KirbyBauer disk diffusion method, and the distribution of 19 kinds of common drug resistance genes was investigated using Polymerase Chain Reaction. The results showed that the resistance rate to nine antibiotics was over 50%, including rifampin (84.76%), ampicillin (73.58%), tetracycline (69.52%), and sulfisoxazole (59.05%). In total, 105 strains of bovine E. coli presented 21 spectra of drug resistance, including eight strains (7.62%, 8/105) that were resistant to one antibiotic and four strains (3.81%, 4/105) that were resistant to 21 antibiotics. The resistance gene detection results showed that the streptomycin-resistance gene strA was found in 73 isolates, accounting for 69.52% of the isolates, followed by the sulfanilamide-resistance genes sul3/sul2 and the aminoglycoside-resistance gene aphA, which accounted for 57.14%, 51.43%, and 50.48%, respectively, of the isolates.Discussion: This study revealed serious drug resistance of bovine E. coli isolates in some areas of Heilongjiang province. Of 105 E. coli isolates, more than 50% were resistant to the following antibacterial drugs: rifampicin, ampicillin, tetracycline, sulfisoxazole, and cephalothin. The isolates were the most sensitive to amikacin, with a sensitivity of 84.76%, followed by sensitivity to ofloxacin, ciprofloxacin, norfloxacin, cefoxitin, and tobramycin. Drug sensitivity tests showed that the drug resistance spectra of the bovine E. coli isolates was different in different regions, indicating that there were multidrug-resistant bovine E. coli isolates in different regions of Heilongjiang province, and that drug resistance differed among different regions. This may be due to prolonged use or overuse of antibiotics in a particular locality. Additionally, because of different management modes of livestock farms, the application of antimicrobial drugs in some farms may have imposed selective pressure on the intestinal flora including E. coli, resulting in the horizontal transmission of drug resistance among the bacteria. The study found that some strains had a resistance phenotype, but no resistance gene, while some had a resistance gene without expressing a resistance phenotype, which is consistent with relevant reports in the literature. This may be related to the same genotype corresponding to different resistance phenotypes, or different levels of gene expression, or different drug metabolic rates. In our study, some strains with certain drug resistance genes were sensitive to the corresponding drug, which may be due to mutations of drug-resistance genes, the loss of a strains resistance phenotype, or the loss of gene function. These issues require further study. This study revealed serious drug resistance of bovine E. coli isolates in some areas of Heilongjiang province. Of 105 E. coli isolates, more than 50% were resistant to the following antibacterial drugs: rifampicin, ampicillin, tetracycline, sulfisoxazole, and cephalothin. The isolates were the most sensitive to amikacin, with a sensitivity of 84.76%, followed by sensitivity to ofloxacin, ciprofloxacin, norfloxacin, cefoxitin, and tobramycin

In-Vitro Study on the Antibacterial and Antioxidant Activity of Four Commercial Essential Oils and In-Situ Evaluation of Their Effect on Quality Deterioration of Pacific White Shrimp (Litopenaeus vannamei) during Cold Storage

The antioxidant and antibacterial properties of four essential oils (oregano essential oil (OEO), tea tree essential oil (TTEO), wild orange essential oil (WOEO), and clove leaf essential oil (CLEO)) were determined. The in-vitro experiment indicated that CLEO had the highest total phenolic content and DPPH scavenging activity, and OEO displayed the highest antibacterial effect, so they were applied to maintain the quality of shrimp for further study. In-situ study, the total viable counts of shrimp were inhibited from 9.05 log CFU/g to 8.18 and 8.34 log CFU/g by 2% of OEO and CLEO treated alone on 10 d. The melanosis ratio was also retarded from 38.16% to 28.98% and 26.35% by the two essential oils. The inhibitory effects of OEO and CLEO on the increase of PPO activity, weight loss, and TCA-soluble peptides, and the decreasing tendency of whiteness, the contents of myofibrillar and sarcoplasmic proteins were also founded. The samples treated with 1% OEO + 1% CLEO had better quality than those treated alone. Therefore, the combination of OEO and CLEO had a synergistic effect, which displayed the highest efficiency to prevent the melanosis, bacterial growth, and protein hydrolysis of shrimp.Peer reviewe

Oxidative stress in a rat model of cotton smoke inhalation-induced pulmonary injury

Background: Smoke inhalation injury refers to airway and lung parenchyma injury and general chemical damage caused by inhaling toxic gases and substances. The aim of this study was to explore the oxidative stress mechanism of cotton smoke inhalation-induced pulmonary injury in a rat model.Materials and Methods: Eighteen male Sprague-Dawley rats were randomly divided into control group, 6 h group, and 24 h group (six rats in each group), which duplicated previous rat cotton smoke-inhalation injury models. Rats in 6 h and 24 h groups were euthanised at 6 h and 24 h after smoke inhalation, respectively. ELISA method was used to detect indicators in the rats’ lung tissue. Quantitative iNOS mRNA and γ-GCS mRNA measurements were performed using a fluorescence PCR method.Results: The concentrations of MDA, NO, iNOS, γ-GCS, iNOS mRNA, and the relative expression of γ-GCS mRNA in the rats’ lung tissues in 6 h and 24 h groups were higher than control group (P < 0.05), and the concentration of NO and relative expressions of iNOS mRNA and γ-GCS mRNA in 24 h group were significantly higher than 6 h group (P < 0.05). The concentrations of GSH in 24 h and 6 h groups were significantly lower than control group (P < 0.05), and that in 24 h group was even significantly lower than 6 h group (P < 0.05).Conclusion: In rats with cotton smoke inhalation-induced pulmonary injury, the increased iNOS mRNA transcription can cause increase of iNOS synthesis and promotion of NO synthesis. The increased γ-GCS mRNA transcription can cause increase of γ-GCS synthesis and but decrease of GSH concentration. The activation of the antioxidant system is insufficient to combat oxidative stress damage. So the oxidant/antioxidant system is imbalanced, leading to gradual aggravation of lung injury.Keywords: Acute lung injury, Smoke inhalation injury, Oxidative stres

QED and relativistic nuclear recoil corrections to the 413 nm tune-out wavelength for the 2\,^3S_1 state of helium

Comparison of high accuracy calculations with precision measurement of the 413 nm tune-out wavelength of the He(2\,^3S_1) state provides a unique test of quantum electro-dynamic (QED). We perform large-scale relativistic-configuration-interaction (RCI) calculations of the tune-out wavelength, that include the mass-shift operator, and fully account for leading relativistic nuclear recoil terms in the Dirac-Coulomb-Breit (DCB) Hamiltonian. We obtain the QED correction to the tune-out wavelength using perturbation theory, and the effect of finite nuclear size is also evaluated. The resulting tune-out wavelengths for the 2\,^3S_1(M_J=0) and 2\,^3S_1(M_J=\pm 1) states are 413.084 26(4) nm and 413.090 15(4) nm, respectively. Compared with the only current experimental value of 413.0938(9stat)(20syst) nm for the 2\,^3S_1(M_J=\pm 1) state, there is 1.8$\sigma$ discrepancy between present theoretical work and experiment, which stimulates further theoretical and higher-precision experimental investigations on the 413 nm tune-out wavelength. In addition, we also determine the QED correction for the static dipole polarizability of the He(2\,^3S_1) state to be 22.5 ppm, which may enable a new test of QED in the future.Comment: 6 pages; 2 figure

Tensed Ontology Based on Simple Partial Logic

Simple partial logic (=SPL) is, broadly speaking, an extensional logic which allows for the truth-value gap. First I give a system of propositional SPL by partializing classical logic, as well as extending it with several non-classical truth-functional operators. Second I show a way based on SPL to construct a system of tensed ontology, by representing tensed statements as two kinds of necessary statements in a linear model that consists of the present and future worlds. Finally I compare that way with other two ways based on Łukasiewicz’s three-valued logic and branching temporal logic